8490 lines
214 KiB
C
8490 lines
214 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* kernel/sched/core.c
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*
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* Core kernel scheduler code and related syscalls
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*
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* Copyright (C) 1991-2002 Linus Torvalds
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*/
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#define CREATE_TRACE_POINTS
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#include <trace/events/sched.h>
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#undef CREATE_TRACE_POINTS
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#include "sched.h"
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#include <linux/nospec.h>
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#include <linux/kcov.h>
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#include <linux/scs.h>
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#include <asm/switch_to.h>
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#include <asm/tlb.h>
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#include "../workqueue_internal.h"
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#include "../../fs/io-wq.h"
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#include "../smpboot.h"
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#include "pelt.h"
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#include "smp.h"
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/*
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* Export tracepoints that act as a bare tracehook (ie: have no trace event
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* associated with them) to allow external modules to probe them.
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*/
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EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_cfs_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_cpu_capacity_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
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DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
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#ifdef CONFIG_SCHED_DEBUG
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/*
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* Debugging: various feature bits
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*
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* If SCHED_DEBUG is disabled, each compilation unit has its own copy of
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* sysctl_sched_features, defined in sched.h, to allow constants propagation
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* at compile time and compiler optimization based on features default.
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*/
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#define SCHED_FEAT(name, enabled) \
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(1UL << __SCHED_FEAT_##name) * enabled |
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const_debug unsigned int sysctl_sched_features =
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#include "features.h"
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0;
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#undef SCHED_FEAT
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#endif
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/*
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* Number of tasks to iterate in a single balance run.
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* Limited because this is done with IRQs disabled.
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*/
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const_debug unsigned int sysctl_sched_nr_migrate = 32;
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/*
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* period over which we measure -rt task CPU usage in us.
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* default: 1s
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*/
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unsigned int sysctl_sched_rt_period = 1000000;
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__read_mostly int scheduler_running;
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/*
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* part of the period that we allow rt tasks to run in us.
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* default: 0.95s
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*/
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int sysctl_sched_rt_runtime = 950000;
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/*
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* Serialization rules:
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*
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* Lock order:
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*
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* p->pi_lock
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* rq->lock
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* hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls)
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*
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* rq1->lock
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* rq2->lock where: rq1 < rq2
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*
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* Regular state:
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*
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* Normal scheduling state is serialized by rq->lock. __schedule() takes the
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* local CPU's rq->lock, it optionally removes the task from the runqueue and
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* always looks at the local rq data structures to find the most elegible task
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* to run next.
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*
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* Task enqueue is also under rq->lock, possibly taken from another CPU.
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* Wakeups from another LLC domain might use an IPI to transfer the enqueue to
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* the local CPU to avoid bouncing the runqueue state around [ see
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* ttwu_queue_wakelist() ]
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*
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* Task wakeup, specifically wakeups that involve migration, are horribly
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* complicated to avoid having to take two rq->locks.
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*
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* Special state:
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*
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* System-calls and anything external will use task_rq_lock() which acquires
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* both p->pi_lock and rq->lock. As a consequence the state they change is
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* stable while holding either lock:
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*
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* - sched_setaffinity()/
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* set_cpus_allowed_ptr(): p->cpus_ptr, p->nr_cpus_allowed
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* - set_user_nice(): p->se.load, p->*prio
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* - __sched_setscheduler(): p->sched_class, p->policy, p->*prio,
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* p->se.load, p->rt_priority,
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* p->dl.dl_{runtime, deadline, period, flags, bw, density}
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* - sched_setnuma(): p->numa_preferred_nid
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* - sched_move_task()/
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* cpu_cgroup_fork(): p->sched_task_group
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* - uclamp_update_active() p->uclamp*
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*
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* p->state <- TASK_*:
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*
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* is changed locklessly using set_current_state(), __set_current_state() or
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* set_special_state(), see their respective comments, or by
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* try_to_wake_up(). This latter uses p->pi_lock to serialize against
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* concurrent self.
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*
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* p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }:
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*
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* is set by activate_task() and cleared by deactivate_task(), under
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* rq->lock. Non-zero indicates the task is runnable, the special
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* ON_RQ_MIGRATING state is used for migration without holding both
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* rq->locks. It indicates task_cpu() is not stable, see task_rq_lock().
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*
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* p->on_cpu <- { 0, 1 }:
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*
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* is set by prepare_task() and cleared by finish_task() such that it will be
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* set before p is scheduled-in and cleared after p is scheduled-out, both
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* under rq->lock. Non-zero indicates the task is running on its CPU.
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*
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* [ The astute reader will observe that it is possible for two tasks on one
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* CPU to have ->on_cpu = 1 at the same time. ]
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*
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* task_cpu(p): is changed by set_task_cpu(), the rules are:
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*
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* - Don't call set_task_cpu() on a blocked task:
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*
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* We don't care what CPU we're not running on, this simplifies hotplug,
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* the CPU assignment of blocked tasks isn't required to be valid.
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*
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* - for try_to_wake_up(), called under p->pi_lock:
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*
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* This allows try_to_wake_up() to only take one rq->lock, see its comment.
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*
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* - for migration called under rq->lock:
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* [ see task_on_rq_migrating() in task_rq_lock() ]
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*
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* o move_queued_task()
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* o detach_task()
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*
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* - for migration called under double_rq_lock():
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*
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* o __migrate_swap_task()
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* o push_rt_task() / pull_rt_task()
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* o push_dl_task() / pull_dl_task()
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* o dl_task_offline_migration()
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*
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*/
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/*
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* __task_rq_lock - lock the rq @p resides on.
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*/
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struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
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__acquires(rq->lock)
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{
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struct rq *rq;
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lockdep_assert_held(&p->pi_lock);
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for (;;) {
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rq = task_rq(p);
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raw_spin_lock(&rq->lock);
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if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
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rq_pin_lock(rq, rf);
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return rq;
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}
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raw_spin_unlock(&rq->lock);
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while (unlikely(task_on_rq_migrating(p)))
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cpu_relax();
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}
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}
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/*
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* task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
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*/
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struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
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__acquires(p->pi_lock)
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__acquires(rq->lock)
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{
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struct rq *rq;
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for (;;) {
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raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
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rq = task_rq(p);
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raw_spin_lock(&rq->lock);
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/*
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* move_queued_task() task_rq_lock()
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*
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* ACQUIRE (rq->lock)
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* [S] ->on_rq = MIGRATING [L] rq = task_rq()
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* WMB (__set_task_cpu()) ACQUIRE (rq->lock);
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* [S] ->cpu = new_cpu [L] task_rq()
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* [L] ->on_rq
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* RELEASE (rq->lock)
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*
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* If we observe the old CPU in task_rq_lock(), the acquire of
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* the old rq->lock will fully serialize against the stores.
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*
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* If we observe the new CPU in task_rq_lock(), the address
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* dependency headed by '[L] rq = task_rq()' and the acquire
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* will pair with the WMB to ensure we then also see migrating.
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*/
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if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
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rq_pin_lock(rq, rf);
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return rq;
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}
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raw_spin_unlock(&rq->lock);
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raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
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while (unlikely(task_on_rq_migrating(p)))
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cpu_relax();
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}
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}
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/*
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* RQ-clock updating methods:
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*/
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static void update_rq_clock_task(struct rq *rq, s64 delta)
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{
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/*
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* In theory, the compile should just see 0 here, and optimize out the call
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* to sched_rt_avg_update. But I don't trust it...
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*/
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s64 __maybe_unused steal = 0, irq_delta = 0;
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#ifdef CONFIG_IRQ_TIME_ACCOUNTING
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irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
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/*
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* Since irq_time is only updated on {soft,}irq_exit, we might run into
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* this case when a previous update_rq_clock() happened inside a
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* {soft,}irq region.
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*
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* When this happens, we stop ->clock_task and only update the
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* prev_irq_time stamp to account for the part that fit, so that a next
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* update will consume the rest. This ensures ->clock_task is
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* monotonic.
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*
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* It does however cause some slight miss-attribution of {soft,}irq
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* time, a more accurate solution would be to update the irq_time using
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* the current rq->clock timestamp, except that would require using
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* atomic ops.
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*/
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if (irq_delta > delta)
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irq_delta = delta;
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rq->prev_irq_time += irq_delta;
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delta -= irq_delta;
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#endif
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#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
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if (static_key_false((¶virt_steal_rq_enabled))) {
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steal = paravirt_steal_clock(cpu_of(rq));
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steal -= rq->prev_steal_time_rq;
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if (unlikely(steal > delta))
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steal = delta;
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rq->prev_steal_time_rq += steal;
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delta -= steal;
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}
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#endif
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rq->clock_task += delta;
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#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
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if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
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update_irq_load_avg(rq, irq_delta + steal);
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#endif
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update_rq_clock_pelt(rq, delta);
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}
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void update_rq_clock(struct rq *rq)
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{
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s64 delta;
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lockdep_assert_held(&rq->lock);
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if (rq->clock_update_flags & RQCF_ACT_SKIP)
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return;
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#ifdef CONFIG_SCHED_DEBUG
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if (sched_feat(WARN_DOUBLE_CLOCK))
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SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
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rq->clock_update_flags |= RQCF_UPDATED;
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#endif
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delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
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if (delta < 0)
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return;
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rq->clock += delta;
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update_rq_clock_task(rq, delta);
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}
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static inline void
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rq_csd_init(struct rq *rq, call_single_data_t *csd, smp_call_func_t func)
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{
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csd->flags = 0;
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csd->func = func;
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csd->info = rq;
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}
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#ifdef CONFIG_SCHED_HRTICK
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/*
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* Use HR-timers to deliver accurate preemption points.
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*/
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static void hrtick_clear(struct rq *rq)
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{
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if (hrtimer_active(&rq->hrtick_timer))
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hrtimer_cancel(&rq->hrtick_timer);
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}
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/*
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* High-resolution timer tick.
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* Runs from hardirq context with interrupts disabled.
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*/
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static enum hrtimer_restart hrtick(struct hrtimer *timer)
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{
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struct rq *rq = container_of(timer, struct rq, hrtick_timer);
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struct rq_flags rf;
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WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
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rq_lock(rq, &rf);
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update_rq_clock(rq);
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rq->curr->sched_class->task_tick(rq, rq->curr, 1);
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rq_unlock(rq, &rf);
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return HRTIMER_NORESTART;
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}
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#ifdef CONFIG_SMP
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static void __hrtick_restart(struct rq *rq)
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{
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struct hrtimer *timer = &rq->hrtick_timer;
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hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
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}
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/*
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* called from hardirq (IPI) context
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*/
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static void __hrtick_start(void *arg)
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{
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struct rq *rq = arg;
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struct rq_flags rf;
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rq_lock(rq, &rf);
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__hrtick_restart(rq);
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rq_unlock(rq, &rf);
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}
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/*
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* Called to set the hrtick timer state.
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*
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* called with rq->lock held and irqs disabled
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*/
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void hrtick_start(struct rq *rq, u64 delay)
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{
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struct hrtimer *timer = &rq->hrtick_timer;
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ktime_t time;
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s64 delta;
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/*
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* Don't schedule slices shorter than 10000ns, that just
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* doesn't make sense and can cause timer DoS.
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*/
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delta = max_t(s64, delay, 10000LL);
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time = ktime_add_ns(timer->base->get_time(), delta);
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hrtimer_set_expires(timer, time);
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if (rq == this_rq())
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__hrtick_restart(rq);
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else
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smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
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}
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#else
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/*
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* Called to set the hrtick timer state.
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*
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* called with rq->lock held and irqs disabled
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*/
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void hrtick_start(struct rq *rq, u64 delay)
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{
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/*
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* Don't schedule slices shorter than 10000ns, that just
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* doesn't make sense. Rely on vruntime for fairness.
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*/
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delay = max_t(u64, delay, 10000LL);
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hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
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HRTIMER_MODE_REL_PINNED_HARD);
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}
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#endif /* CONFIG_SMP */
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static void hrtick_rq_init(struct rq *rq)
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{
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#ifdef CONFIG_SMP
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rq_csd_init(rq, &rq->hrtick_csd, __hrtick_start);
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#endif
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hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
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rq->hrtick_timer.function = hrtick;
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}
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#else /* CONFIG_SCHED_HRTICK */
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static inline void hrtick_clear(struct rq *rq)
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{
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}
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static inline void hrtick_rq_init(struct rq *rq)
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{
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}
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#endif /* CONFIG_SCHED_HRTICK */
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/*
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* cmpxchg based fetch_or, macro so it works for different integer types
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*/
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#define fetch_or(ptr, mask) \
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({ \
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typeof(ptr) _ptr = (ptr); \
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typeof(mask) _mask = (mask); \
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typeof(*_ptr) _old, _val = *_ptr; \
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\
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for (;;) { \
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_old = cmpxchg(_ptr, _val, _val | _mask); \
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if (_old == _val) \
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break; \
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_val = _old; \
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} \
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_old; \
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})
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#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
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/*
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* Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
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* this avoids any races wrt polling state changes and thereby avoids
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* spurious IPIs.
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*/
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static bool set_nr_and_not_polling(struct task_struct *p)
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{
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struct thread_info *ti = task_thread_info(p);
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return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
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}
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/*
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* Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
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*
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* If this returns true, then the idle task promises to call
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* sched_ttwu_pending() and reschedule soon.
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*/
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static bool set_nr_if_polling(struct task_struct *p)
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{
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struct thread_info *ti = task_thread_info(p);
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typeof(ti->flags) old, val = READ_ONCE(ti->flags);
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for (;;) {
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if (!(val & _TIF_POLLING_NRFLAG))
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return false;
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if (val & _TIF_NEED_RESCHED)
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return true;
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old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
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if (old == val)
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break;
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val = old;
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}
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return true;
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}
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#else
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static bool set_nr_and_not_polling(struct task_struct *p)
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{
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set_tsk_need_resched(p);
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return true;
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}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static bool set_nr_if_polling(struct task_struct *p)
|
|
{
|
|
return false;
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task)
|
|
{
|
|
struct wake_q_node *node = &task->wake_q;
|
|
|
|
/*
|
|
* Atomically grab the task, if ->wake_q is !nil already it means
|
|
* its already queued (either by us or someone else) and will get the
|
|
* wakeup due to that.
|
|
*
|
|
* In order to ensure that a pending wakeup will observe our pending
|
|
* state, even in the failed case, an explicit smp_mb() must be used.
|
|
*/
|
|
smp_mb__before_atomic();
|
|
if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL)))
|
|
return false;
|
|
|
|
/*
|
|
* The head is context local, there can be no concurrency.
|
|
*/
|
|
*head->lastp = node;
|
|
head->lastp = &node->next;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* wake_q_add() - queue a wakeup for 'later' waking.
|
|
* @head: the wake_q_head to add @task to
|
|
* @task: the task to queue for 'later' wakeup
|
|
*
|
|
* Queue a task for later wakeup, most likely by the wake_up_q() call in the
|
|
* same context, _HOWEVER_ this is not guaranteed, the wakeup can come
|
|
* instantly.
|
|
*
|
|
* This function must be used as-if it were wake_up_process(); IOW the task
|
|
* must be ready to be woken at this location.
|
|
*/
|
|
void wake_q_add(struct wake_q_head *head, struct task_struct *task)
|
|
{
|
|
if (__wake_q_add(head, task))
|
|
get_task_struct(task);
|
|
}
|
|
|
|
/**
|
|
* wake_q_add_safe() - safely queue a wakeup for 'later' waking.
|
|
* @head: the wake_q_head to add @task to
|
|
* @task: the task to queue for 'later' wakeup
|
|
*
|
|
* Queue a task for later wakeup, most likely by the wake_up_q() call in the
|
|
* same context, _HOWEVER_ this is not guaranteed, the wakeup can come
|
|
* instantly.
|
|
*
|
|
* This function must be used as-if it were wake_up_process(); IOW the task
|
|
* must be ready to be woken at this location.
|
|
*
|
|
* This function is essentially a task-safe equivalent to wake_q_add(). Callers
|
|
* that already hold reference to @task can call the 'safe' version and trust
|
|
* wake_q to do the right thing depending whether or not the @task is already
|
|
* queued for wakeup.
|
|
*/
|
|
void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task)
|
|
{
|
|
if (!__wake_q_add(head, task))
|
|
put_task_struct(task);
|
|
}
|
|
|
|
void wake_up_q(struct wake_q_head *head)
|
|
{
|
|
struct wake_q_node *node = head->first;
|
|
|
|
while (node != WAKE_Q_TAIL) {
|
|
struct task_struct *task;
|
|
|
|
task = container_of(node, struct task_struct, wake_q);
|
|
BUG_ON(!task);
|
|
/* Task can safely be re-inserted now: */
|
|
node = node->next;
|
|
task->wake_q.next = NULL;
|
|
|
|
/*
|
|
* wake_up_process() executes a full barrier, which pairs with
|
|
* the queueing in wake_q_add() so as not to miss wakeups.
|
|
*/
|
|
wake_up_process(task);
|
|
put_task_struct(task);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* resched_curr - mark rq's current task 'to be rescheduled now'.
|
|
*
|
|
* On UP this means the setting of the need_resched flag, on SMP it
|
|
* might also involve a cross-CPU call to trigger the scheduler on
|
|
* the target CPU.
|
|
*/
|
|
void resched_curr(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
int cpu;
|
|
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
if (test_tsk_need_resched(curr))
|
|
return;
|
|
|
|
cpu = cpu_of(rq);
|
|
|
|
if (cpu == smp_processor_id()) {
|
|
set_tsk_need_resched(curr);
|
|
set_preempt_need_resched();
|
|
return;
|
|
}
|
|
|
|
if (set_nr_and_not_polling(curr))
|
|
smp_send_reschedule(cpu);
|
|
else
|
|
trace_sched_wake_idle_without_ipi(cpu);
|
|
}
|
|
|
|
void resched_cpu(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
if (cpu_online(cpu) || cpu == smp_processor_id())
|
|
resched_curr(rq);
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
/*
|
|
* In the semi idle case, use the nearest busy CPU for migrating timers
|
|
* from an idle CPU. This is good for power-savings.
|
|
*
|
|
* We don't do similar optimization for completely idle system, as
|
|
* selecting an idle CPU will add more delays to the timers than intended
|
|
* (as that CPU's timer base may not be uptodate wrt jiffies etc).
|
|
*/
|
|
int get_nohz_timer_target(void)
|
|
{
|
|
int i, cpu = smp_processor_id(), default_cpu = -1;
|
|
struct sched_domain *sd;
|
|
|
|
if (housekeeping_cpu(cpu, HK_FLAG_TIMER)) {
|
|
if (!idle_cpu(cpu))
|
|
return cpu;
|
|
default_cpu = cpu;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
for_each_cpu_and(i, sched_domain_span(sd),
|
|
housekeeping_cpumask(HK_FLAG_TIMER)) {
|
|
if (cpu == i)
|
|
continue;
|
|
|
|
if (!idle_cpu(i)) {
|
|
cpu = i;
|
|
goto unlock;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (default_cpu == -1)
|
|
default_cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
|
|
cpu = default_cpu;
|
|
unlock:
|
|
rcu_read_unlock();
|
|
return cpu;
|
|
}
|
|
|
|
/*
|
|
* When add_timer_on() enqueues a timer into the timer wheel of an
|
|
* idle CPU then this timer might expire before the next timer event
|
|
* which is scheduled to wake up that CPU. In case of a completely
|
|
* idle system the next event might even be infinite time into the
|
|
* future. wake_up_idle_cpu() ensures that the CPU is woken up and
|
|
* leaves the inner idle loop so the newly added timer is taken into
|
|
* account when the CPU goes back to idle and evaluates the timer
|
|
* wheel for the next timer event.
|
|
*/
|
|
static void wake_up_idle_cpu(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (cpu == smp_processor_id())
|
|
return;
|
|
|
|
if (set_nr_and_not_polling(rq->idle))
|
|
smp_send_reschedule(cpu);
|
|
else
|
|
trace_sched_wake_idle_without_ipi(cpu);
|
|
}
|
|
|
|
static bool wake_up_full_nohz_cpu(int cpu)
|
|
{
|
|
/*
|
|
* We just need the target to call irq_exit() and re-evaluate
|
|
* the next tick. The nohz full kick at least implies that.
|
|
* If needed we can still optimize that later with an
|
|
* empty IRQ.
|
|
*/
|
|
if (cpu_is_offline(cpu))
|
|
return true; /* Don't try to wake offline CPUs. */
|
|
if (tick_nohz_full_cpu(cpu)) {
|
|
if (cpu != smp_processor_id() ||
|
|
tick_nohz_tick_stopped())
|
|
tick_nohz_full_kick_cpu(cpu);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Wake up the specified CPU. If the CPU is going offline, it is the
|
|
* caller's responsibility to deal with the lost wakeup, for example,
|
|
* by hooking into the CPU_DEAD notifier like timers and hrtimers do.
|
|
*/
|
|
void wake_up_nohz_cpu(int cpu)
|
|
{
|
|
if (!wake_up_full_nohz_cpu(cpu))
|
|
wake_up_idle_cpu(cpu);
|
|
}
|
|
|
|
static void nohz_csd_func(void *info)
|
|
{
|
|
struct rq *rq = info;
|
|
int cpu = cpu_of(rq);
|
|
unsigned int flags;
|
|
|
|
/*
|
|
* Release the rq::nohz_csd.
|
|
*/
|
|
flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
|
|
WARN_ON(!(flags & NOHZ_KICK_MASK));
|
|
|
|
rq->idle_balance = idle_cpu(cpu);
|
|
if (rq->idle_balance && !need_resched()) {
|
|
rq->nohz_idle_balance = flags;
|
|
raise_softirq_irqoff(SCHED_SOFTIRQ);
|
|
}
|
|
}
|
|
|
|
#endif /* CONFIG_NO_HZ_COMMON */
|
|
|
|
#ifdef CONFIG_NO_HZ_FULL
|
|
bool sched_can_stop_tick(struct rq *rq)
|
|
{
|
|
int fifo_nr_running;
|
|
|
|
/* Deadline tasks, even if single, need the tick */
|
|
if (rq->dl.dl_nr_running)
|
|
return false;
|
|
|
|
/*
|
|
* If there are more than one RR tasks, we need the tick to effect the
|
|
* actual RR behaviour.
|
|
*/
|
|
if (rq->rt.rr_nr_running) {
|
|
if (rq->rt.rr_nr_running == 1)
|
|
return true;
|
|
else
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* If there's no RR tasks, but FIFO tasks, we can skip the tick, no
|
|
* forced preemption between FIFO tasks.
|
|
*/
|
|
fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
|
|
if (fifo_nr_running)
|
|
return true;
|
|
|
|
/*
|
|
* If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
|
|
* if there's more than one we need the tick for involuntary
|
|
* preemption.
|
|
*/
|
|
if (rq->nr_running > 1)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
#endif /* CONFIG_NO_HZ_FULL */
|
|
#endif /* CONFIG_SMP */
|
|
|
|
#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
|
|
(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
|
|
/*
|
|
* Iterate task_group tree rooted at *from, calling @down when first entering a
|
|
* node and @up when leaving it for the final time.
|
|
*
|
|
* Caller must hold rcu_lock or sufficient equivalent.
|
|
*/
|
|
int walk_tg_tree_from(struct task_group *from,
|
|
tg_visitor down, tg_visitor up, void *data)
|
|
{
|
|
struct task_group *parent, *child;
|
|
int ret;
|
|
|
|
parent = from;
|
|
|
|
down:
|
|
ret = (*down)(parent, data);
|
|
if (ret)
|
|
goto out;
|
|
list_for_each_entry_rcu(child, &parent->children, siblings) {
|
|
parent = child;
|
|
goto down;
|
|
|
|
up:
|
|
continue;
|
|
}
|
|
ret = (*up)(parent, data);
|
|
if (ret || parent == from)
|
|
goto out;
|
|
|
|
child = parent;
|
|
parent = parent->parent;
|
|
if (parent)
|
|
goto up;
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
int tg_nop(struct task_group *tg, void *data)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static void set_load_weight(struct task_struct *p, bool update_load)
|
|
{
|
|
int prio = p->static_prio - MAX_RT_PRIO;
|
|
struct load_weight *load = &p->se.load;
|
|
|
|
/*
|
|
* SCHED_IDLE tasks get minimal weight:
|
|
*/
|
|
if (task_has_idle_policy(p)) {
|
|
load->weight = scale_load(WEIGHT_IDLEPRIO);
|
|
load->inv_weight = WMULT_IDLEPRIO;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* SCHED_OTHER tasks have to update their load when changing their
|
|
* weight
|
|
*/
|
|
if (update_load && p->sched_class == &fair_sched_class) {
|
|
reweight_task(p, prio);
|
|
} else {
|
|
load->weight = scale_load(sched_prio_to_weight[prio]);
|
|
load->inv_weight = sched_prio_to_wmult[prio];
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK
|
|
/*
|
|
* Serializes updates of utilization clamp values
|
|
*
|
|
* The (slow-path) user-space triggers utilization clamp value updates which
|
|
* can require updates on (fast-path) scheduler's data structures used to
|
|
* support enqueue/dequeue operations.
|
|
* While the per-CPU rq lock protects fast-path update operations, user-space
|
|
* requests are serialized using a mutex to reduce the risk of conflicting
|
|
* updates or API abuses.
|
|
*/
|
|
static DEFINE_MUTEX(uclamp_mutex);
|
|
|
|
/* Max allowed minimum utilization */
|
|
unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
|
|
|
|
/* Max allowed maximum utilization */
|
|
unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
|
|
|
|
/*
|
|
* By default RT tasks run at the maximum performance point/capacity of the
|
|
* system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to
|
|
* SCHED_CAPACITY_SCALE.
|
|
*
|
|
* This knob allows admins to change the default behavior when uclamp is being
|
|
* used. In battery powered devices, particularly, running at the maximum
|
|
* capacity and frequency will increase energy consumption and shorten the
|
|
* battery life.
|
|
*
|
|
* This knob only affects RT tasks that their uclamp_se->user_defined == false.
|
|
*
|
|
* This knob will not override the system default sched_util_clamp_min defined
|
|
* above.
|
|
*/
|
|
unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
|
|
|
|
/* All clamps are required to be less or equal than these values */
|
|
static struct uclamp_se uclamp_default[UCLAMP_CNT];
|
|
|
|
/*
|
|
* This static key is used to reduce the uclamp overhead in the fast path. It
|
|
* primarily disables the call to uclamp_rq_{inc, dec}() in
|
|
* enqueue/dequeue_task().
|
|
*
|
|
* This allows users to continue to enable uclamp in their kernel config with
|
|
* minimum uclamp overhead in the fast path.
|
|
*
|
|
* As soon as userspace modifies any of the uclamp knobs, the static key is
|
|
* enabled, since we have an actual users that make use of uclamp
|
|
* functionality.
|
|
*
|
|
* The knobs that would enable this static key are:
|
|
*
|
|
* * A task modifying its uclamp value with sched_setattr().
|
|
* * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs.
|
|
* * An admin modifying the cgroup cpu.uclamp.{min, max}
|
|
*/
|
|
DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
|
|
|
|
/* Integer rounded range for each bucket */
|
|
#define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
|
|
|
|
#define for_each_clamp_id(clamp_id) \
|
|
for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
|
|
|
|
static inline unsigned int uclamp_bucket_id(unsigned int clamp_value)
|
|
{
|
|
return clamp_value / UCLAMP_BUCKET_DELTA;
|
|
}
|
|
|
|
static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
|
|
{
|
|
if (clamp_id == UCLAMP_MIN)
|
|
return 0;
|
|
return SCHED_CAPACITY_SCALE;
|
|
}
|
|
|
|
static inline void uclamp_se_set(struct uclamp_se *uc_se,
|
|
unsigned int value, bool user_defined)
|
|
{
|
|
uc_se->value = value;
|
|
uc_se->bucket_id = uclamp_bucket_id(value);
|
|
uc_se->user_defined = user_defined;
|
|
}
|
|
|
|
static inline unsigned int
|
|
uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id,
|
|
unsigned int clamp_value)
|
|
{
|
|
/*
|
|
* Avoid blocked utilization pushing up the frequency when we go
|
|
* idle (which drops the max-clamp) by retaining the last known
|
|
* max-clamp.
|
|
*/
|
|
if (clamp_id == UCLAMP_MAX) {
|
|
rq->uclamp_flags |= UCLAMP_FLAG_IDLE;
|
|
return clamp_value;
|
|
}
|
|
|
|
return uclamp_none(UCLAMP_MIN);
|
|
}
|
|
|
|
static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id,
|
|
unsigned int clamp_value)
|
|
{
|
|
/* Reset max-clamp retention only on idle exit */
|
|
if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE))
|
|
return;
|
|
|
|
WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value);
|
|
}
|
|
|
|
static inline
|
|
unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id,
|
|
unsigned int clamp_value)
|
|
{
|
|
struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket;
|
|
int bucket_id = UCLAMP_BUCKETS - 1;
|
|
|
|
/*
|
|
* Since both min and max clamps are max aggregated, find the
|
|
* top most bucket with tasks in.
|
|
*/
|
|
for ( ; bucket_id >= 0; bucket_id--) {
|
|
if (!bucket[bucket_id].tasks)
|
|
continue;
|
|
return bucket[bucket_id].value;
|
|
}
|
|
|
|
/* No tasks -- default clamp values */
|
|
return uclamp_idle_value(rq, clamp_id, clamp_value);
|
|
}
|
|
|
|
static void __uclamp_update_util_min_rt_default(struct task_struct *p)
|
|
{
|
|
unsigned int default_util_min;
|
|
struct uclamp_se *uc_se;
|
|
|
|
lockdep_assert_held(&p->pi_lock);
|
|
|
|
uc_se = &p->uclamp_req[UCLAMP_MIN];
|
|
|
|
/* Only sync if user didn't override the default */
|
|
if (uc_se->user_defined)
|
|
return;
|
|
|
|
default_util_min = sysctl_sched_uclamp_util_min_rt_default;
|
|
uclamp_se_set(uc_se, default_util_min, false);
|
|
}
|
|
|
|
static void uclamp_update_util_min_rt_default(struct task_struct *p)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
if (!rt_task(p))
|
|
return;
|
|
|
|
/* Protect updates to p->uclamp_* */
|
|
rq = task_rq_lock(p, &rf);
|
|
__uclamp_update_util_min_rt_default(p);
|
|
task_rq_unlock(rq, p, &rf);
|
|
}
|
|
|
|
static void uclamp_sync_util_min_rt_default(void)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
/*
|
|
* copy_process() sysctl_uclamp
|
|
* uclamp_min_rt = X;
|
|
* write_lock(&tasklist_lock) read_lock(&tasklist_lock)
|
|
* // link thread smp_mb__after_spinlock()
|
|
* write_unlock(&tasklist_lock) read_unlock(&tasklist_lock);
|
|
* sched_post_fork() for_each_process_thread()
|
|
* __uclamp_sync_rt() __uclamp_sync_rt()
|
|
*
|
|
* Ensures that either sched_post_fork() will observe the new
|
|
* uclamp_min_rt or for_each_process_thread() will observe the new
|
|
* task.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
smp_mb__after_spinlock();
|
|
read_unlock(&tasklist_lock);
|
|
|
|
rcu_read_lock();
|
|
for_each_process_thread(g, p)
|
|
uclamp_update_util_min_rt_default(p);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static inline struct uclamp_se
|
|
uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_se uc_req = p->uclamp_req[clamp_id];
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
struct uclamp_se uc_max;
|
|
|
|
/*
|
|
* Tasks in autogroups or root task group will be
|
|
* restricted by system defaults.
|
|
*/
|
|
if (task_group_is_autogroup(task_group(p)))
|
|
return uc_req;
|
|
if (task_group(p) == &root_task_group)
|
|
return uc_req;
|
|
|
|
uc_max = task_group(p)->uclamp[clamp_id];
|
|
if (uc_req.value > uc_max.value || !uc_req.user_defined)
|
|
return uc_max;
|
|
#endif
|
|
|
|
return uc_req;
|
|
}
|
|
|
|
/*
|
|
* The effective clamp bucket index of a task depends on, by increasing
|
|
* priority:
|
|
* - the task specific clamp value, when explicitly requested from userspace
|
|
* - the task group effective clamp value, for tasks not either in the root
|
|
* group or in an autogroup
|
|
* - the system default clamp value, defined by the sysadmin
|
|
*/
|
|
static inline struct uclamp_se
|
|
uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id);
|
|
struct uclamp_se uc_max = uclamp_default[clamp_id];
|
|
|
|
/* System default restrictions always apply */
|
|
if (unlikely(uc_req.value > uc_max.value))
|
|
return uc_max;
|
|
|
|
return uc_req;
|
|
}
|
|
|
|
unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_se uc_eff;
|
|
|
|
/* Task currently refcounted: use back-annotated (effective) value */
|
|
if (p->uclamp[clamp_id].active)
|
|
return (unsigned long)p->uclamp[clamp_id].value;
|
|
|
|
uc_eff = uclamp_eff_get(p, clamp_id);
|
|
|
|
return (unsigned long)uc_eff.value;
|
|
}
|
|
|
|
/*
|
|
* When a task is enqueued on a rq, the clamp bucket currently defined by the
|
|
* task's uclamp::bucket_id is refcounted on that rq. This also immediately
|
|
* updates the rq's clamp value if required.
|
|
*
|
|
* Tasks can have a task-specific value requested from user-space, track
|
|
* within each bucket the maximum value for tasks refcounted in it.
|
|
* This "local max aggregation" allows to track the exact "requested" value
|
|
* for each bucket when all its RUNNABLE tasks require the same clamp.
|
|
*/
|
|
static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
|
|
enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
|
|
struct uclamp_se *uc_se = &p->uclamp[clamp_id];
|
|
struct uclamp_bucket *bucket;
|
|
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
/* Update task effective clamp */
|
|
p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id);
|
|
|
|
bucket = &uc_rq->bucket[uc_se->bucket_id];
|
|
bucket->tasks++;
|
|
uc_se->active = true;
|
|
|
|
uclamp_idle_reset(rq, clamp_id, uc_se->value);
|
|
|
|
/*
|
|
* Local max aggregation: rq buckets always track the max
|
|
* "requested" clamp value of its RUNNABLE tasks.
|
|
*/
|
|
if (bucket->tasks == 1 || uc_se->value > bucket->value)
|
|
bucket->value = uc_se->value;
|
|
|
|
if (uc_se->value > READ_ONCE(uc_rq->value))
|
|
WRITE_ONCE(uc_rq->value, uc_se->value);
|
|
}
|
|
|
|
/*
|
|
* When a task is dequeued from a rq, the clamp bucket refcounted by the task
|
|
* is released. If this is the last task reference counting the rq's max
|
|
* active clamp value, then the rq's clamp value is updated.
|
|
*
|
|
* Both refcounted tasks and rq's cached clamp values are expected to be
|
|
* always valid. If it's detected they are not, as defensive programming,
|
|
* enforce the expected state and warn.
|
|
*/
|
|
static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p,
|
|
enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
|
|
struct uclamp_se *uc_se = &p->uclamp[clamp_id];
|
|
struct uclamp_bucket *bucket;
|
|
unsigned int bkt_clamp;
|
|
unsigned int rq_clamp;
|
|
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
/*
|
|
* If sched_uclamp_used was enabled after task @p was enqueued,
|
|
* we could end up with unbalanced call to uclamp_rq_dec_id().
|
|
*
|
|
* In this case the uc_se->active flag should be false since no uclamp
|
|
* accounting was performed at enqueue time and we can just return
|
|
* here.
|
|
*
|
|
* Need to be careful of the following enqeueue/dequeue ordering
|
|
* problem too
|
|
*
|
|
* enqueue(taskA)
|
|
* // sched_uclamp_used gets enabled
|
|
* enqueue(taskB)
|
|
* dequeue(taskA)
|
|
* // Must not decrement bukcet->tasks here
|
|
* dequeue(taskB)
|
|
*
|
|
* where we could end up with stale data in uc_se and
|
|
* bucket[uc_se->bucket_id].
|
|
*
|
|
* The following check here eliminates the possibility of such race.
|
|
*/
|
|
if (unlikely(!uc_se->active))
|
|
return;
|
|
|
|
bucket = &uc_rq->bucket[uc_se->bucket_id];
|
|
|
|
SCHED_WARN_ON(!bucket->tasks);
|
|
if (likely(bucket->tasks))
|
|
bucket->tasks--;
|
|
|
|
uc_se->active = false;
|
|
|
|
/*
|
|
* Keep "local max aggregation" simple and accept to (possibly)
|
|
* overboost some RUNNABLE tasks in the same bucket.
|
|
* The rq clamp bucket value is reset to its base value whenever
|
|
* there are no more RUNNABLE tasks refcounting it.
|
|
*/
|
|
if (likely(bucket->tasks))
|
|
return;
|
|
|
|
rq_clamp = READ_ONCE(uc_rq->value);
|
|
/*
|
|
* Defensive programming: this should never happen. If it happens,
|
|
* e.g. due to future modification, warn and fixup the expected value.
|
|
*/
|
|
SCHED_WARN_ON(bucket->value > rq_clamp);
|
|
if (bucket->value >= rq_clamp) {
|
|
bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value);
|
|
WRITE_ONCE(uc_rq->value, bkt_clamp);
|
|
}
|
|
}
|
|
|
|
static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
|
|
/*
|
|
* Avoid any overhead until uclamp is actually used by the userspace.
|
|
*
|
|
* The condition is constructed such that a NOP is generated when
|
|
* sched_uclamp_used is disabled.
|
|
*/
|
|
if (!static_branch_unlikely(&sched_uclamp_used))
|
|
return;
|
|
|
|
if (unlikely(!p->sched_class->uclamp_enabled))
|
|
return;
|
|
|
|
for_each_clamp_id(clamp_id)
|
|
uclamp_rq_inc_id(rq, p, clamp_id);
|
|
|
|
/* Reset clamp idle holding when there is one RUNNABLE task */
|
|
if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
|
|
rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
|
|
}
|
|
|
|
static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
|
|
/*
|
|
* Avoid any overhead until uclamp is actually used by the userspace.
|
|
*
|
|
* The condition is constructed such that a NOP is generated when
|
|
* sched_uclamp_used is disabled.
|
|
*/
|
|
if (!static_branch_unlikely(&sched_uclamp_used))
|
|
return;
|
|
|
|
if (unlikely(!p->sched_class->uclamp_enabled))
|
|
return;
|
|
|
|
for_each_clamp_id(clamp_id)
|
|
uclamp_rq_dec_id(rq, p, clamp_id);
|
|
}
|
|
|
|
static inline void
|
|
uclamp_update_active(struct task_struct *p, enum uclamp_id clamp_id)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
/*
|
|
* Lock the task and the rq where the task is (or was) queued.
|
|
*
|
|
* We might lock the (previous) rq of a !RUNNABLE task, but that's the
|
|
* price to pay to safely serialize util_{min,max} updates with
|
|
* enqueues, dequeues and migration operations.
|
|
* This is the same locking schema used by __set_cpus_allowed_ptr().
|
|
*/
|
|
rq = task_rq_lock(p, &rf);
|
|
|
|
/*
|
|
* Setting the clamp bucket is serialized by task_rq_lock().
|
|
* If the task is not yet RUNNABLE and its task_struct is not
|
|
* affecting a valid clamp bucket, the next time it's enqueued,
|
|
* it will already see the updated clamp bucket value.
|
|
*/
|
|
if (p->uclamp[clamp_id].active) {
|
|
uclamp_rq_dec_id(rq, p, clamp_id);
|
|
uclamp_rq_inc_id(rq, p, clamp_id);
|
|
}
|
|
|
|
task_rq_unlock(rq, p, &rf);
|
|
}
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
static inline void
|
|
uclamp_update_active_tasks(struct cgroup_subsys_state *css,
|
|
unsigned int clamps)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
struct css_task_iter it;
|
|
struct task_struct *p;
|
|
|
|
css_task_iter_start(css, 0, &it);
|
|
while ((p = css_task_iter_next(&it))) {
|
|
for_each_clamp_id(clamp_id) {
|
|
if ((0x1 << clamp_id) & clamps)
|
|
uclamp_update_active(p, clamp_id);
|
|
}
|
|
}
|
|
css_task_iter_end(&it);
|
|
}
|
|
|
|
static void cpu_util_update_eff(struct cgroup_subsys_state *css);
|
|
static void uclamp_update_root_tg(void)
|
|
{
|
|
struct task_group *tg = &root_task_group;
|
|
|
|
uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN],
|
|
sysctl_sched_uclamp_util_min, false);
|
|
uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX],
|
|
sysctl_sched_uclamp_util_max, false);
|
|
|
|
rcu_read_lock();
|
|
cpu_util_update_eff(&root_task_group.css);
|
|
rcu_read_unlock();
|
|
}
|
|
#else
|
|
static void uclamp_update_root_tg(void) { }
|
|
#endif
|
|
|
|
int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
bool update_root_tg = false;
|
|
int old_min, old_max, old_min_rt;
|
|
int result;
|
|
|
|
mutex_lock(&uclamp_mutex);
|
|
old_min = sysctl_sched_uclamp_util_min;
|
|
old_max = sysctl_sched_uclamp_util_max;
|
|
old_min_rt = sysctl_sched_uclamp_util_min_rt_default;
|
|
|
|
result = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
if (result)
|
|
goto undo;
|
|
if (!write)
|
|
goto done;
|
|
|
|
if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max ||
|
|
sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE ||
|
|
sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) {
|
|
|
|
result = -EINVAL;
|
|
goto undo;
|
|
}
|
|
|
|
if (old_min != sysctl_sched_uclamp_util_min) {
|
|
uclamp_se_set(&uclamp_default[UCLAMP_MIN],
|
|
sysctl_sched_uclamp_util_min, false);
|
|
update_root_tg = true;
|
|
}
|
|
if (old_max != sysctl_sched_uclamp_util_max) {
|
|
uclamp_se_set(&uclamp_default[UCLAMP_MAX],
|
|
sysctl_sched_uclamp_util_max, false);
|
|
update_root_tg = true;
|
|
}
|
|
|
|
if (update_root_tg) {
|
|
static_branch_enable(&sched_uclamp_used);
|
|
uclamp_update_root_tg();
|
|
}
|
|
|
|
if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) {
|
|
static_branch_enable(&sched_uclamp_used);
|
|
uclamp_sync_util_min_rt_default();
|
|
}
|
|
|
|
/*
|
|
* We update all RUNNABLE tasks only when task groups are in use.
|
|
* Otherwise, keep it simple and do just a lazy update at each next
|
|
* task enqueue time.
|
|
*/
|
|
|
|
goto done;
|
|
|
|
undo:
|
|
sysctl_sched_uclamp_util_min = old_min;
|
|
sysctl_sched_uclamp_util_max = old_max;
|
|
sysctl_sched_uclamp_util_min_rt_default = old_min_rt;
|
|
done:
|
|
mutex_unlock(&uclamp_mutex);
|
|
|
|
return result;
|
|
}
|
|
|
|
static int uclamp_validate(struct task_struct *p,
|
|
const struct sched_attr *attr)
|
|
{
|
|
unsigned int lower_bound = p->uclamp_req[UCLAMP_MIN].value;
|
|
unsigned int upper_bound = p->uclamp_req[UCLAMP_MAX].value;
|
|
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN)
|
|
lower_bound = attr->sched_util_min;
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX)
|
|
upper_bound = attr->sched_util_max;
|
|
|
|
if (lower_bound > upper_bound)
|
|
return -EINVAL;
|
|
if (upper_bound > SCHED_CAPACITY_SCALE)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* We have valid uclamp attributes; make sure uclamp is enabled.
|
|
*
|
|
* We need to do that here, because enabling static branches is a
|
|
* blocking operation which obviously cannot be done while holding
|
|
* scheduler locks.
|
|
*/
|
|
static_branch_enable(&sched_uclamp_used);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __setscheduler_uclamp(struct task_struct *p,
|
|
const struct sched_attr *attr)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
|
|
/*
|
|
* On scheduling class change, reset to default clamps for tasks
|
|
* without a task-specific value.
|
|
*/
|
|
for_each_clamp_id(clamp_id) {
|
|
struct uclamp_se *uc_se = &p->uclamp_req[clamp_id];
|
|
|
|
/* Keep using defined clamps across class changes */
|
|
if (uc_se->user_defined)
|
|
continue;
|
|
|
|
/*
|
|
* RT by default have a 100% boost value that could be modified
|
|
* at runtime.
|
|
*/
|
|
if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
|
|
__uclamp_update_util_min_rt_default(p);
|
|
else
|
|
uclamp_se_set(uc_se, uclamp_none(clamp_id), false);
|
|
|
|
}
|
|
|
|
if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
|
|
return;
|
|
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) {
|
|
uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
|
|
attr->sched_util_min, true);
|
|
}
|
|
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) {
|
|
uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
|
|
attr->sched_util_max, true);
|
|
}
|
|
}
|
|
|
|
static void uclamp_fork(struct task_struct *p)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
|
|
/*
|
|
* We don't need to hold task_rq_lock() when updating p->uclamp_* here
|
|
* as the task is still at its early fork stages.
|
|
*/
|
|
for_each_clamp_id(clamp_id)
|
|
p->uclamp[clamp_id].active = false;
|
|
|
|
if (likely(!p->sched_reset_on_fork))
|
|
return;
|
|
|
|
for_each_clamp_id(clamp_id) {
|
|
uclamp_se_set(&p->uclamp_req[clamp_id],
|
|
uclamp_none(clamp_id), false);
|
|
}
|
|
}
|
|
|
|
static void uclamp_post_fork(struct task_struct *p)
|
|
{
|
|
uclamp_update_util_min_rt_default(p);
|
|
}
|
|
|
|
static void __init init_uclamp_rq(struct rq *rq)
|
|
{
|
|
enum uclamp_id clamp_id;
|
|
struct uclamp_rq *uc_rq = rq->uclamp;
|
|
|
|
for_each_clamp_id(clamp_id) {
|
|
uc_rq[clamp_id] = (struct uclamp_rq) {
|
|
.value = uclamp_none(clamp_id)
|
|
};
|
|
}
|
|
|
|
rq->uclamp_flags = 0;
|
|
}
|
|
|
|
static void __init init_uclamp(void)
|
|
{
|
|
struct uclamp_se uc_max = {};
|
|
enum uclamp_id clamp_id;
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu)
|
|
init_uclamp_rq(cpu_rq(cpu));
|
|
|
|
for_each_clamp_id(clamp_id) {
|
|
uclamp_se_set(&init_task.uclamp_req[clamp_id],
|
|
uclamp_none(clamp_id), false);
|
|
}
|
|
|
|
/* System defaults allow max clamp values for both indexes */
|
|
uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false);
|
|
for_each_clamp_id(clamp_id) {
|
|
uclamp_default[clamp_id] = uc_max;
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
root_task_group.uclamp_req[clamp_id] = uc_max;
|
|
root_task_group.uclamp[clamp_id] = uc_max;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#else /* CONFIG_UCLAMP_TASK */
|
|
static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { }
|
|
static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { }
|
|
static inline int uclamp_validate(struct task_struct *p,
|
|
const struct sched_attr *attr)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
static void __setscheduler_uclamp(struct task_struct *p,
|
|
const struct sched_attr *attr) { }
|
|
static inline void uclamp_fork(struct task_struct *p) { }
|
|
static inline void uclamp_post_fork(struct task_struct *p) { }
|
|
static inline void init_uclamp(void) { }
|
|
#endif /* CONFIG_UCLAMP_TASK */
|
|
|
|
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
if (!(flags & ENQUEUE_NOCLOCK))
|
|
update_rq_clock(rq);
|
|
|
|
if (!(flags & ENQUEUE_RESTORE)) {
|
|
sched_info_queued(rq, p);
|
|
psi_enqueue(p, flags & ENQUEUE_WAKEUP);
|
|
}
|
|
|
|
uclamp_rq_inc(rq, p);
|
|
p->sched_class->enqueue_task(rq, p, flags);
|
|
}
|
|
|
|
static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
if (!(flags & DEQUEUE_NOCLOCK))
|
|
update_rq_clock(rq);
|
|
|
|
if (!(flags & DEQUEUE_SAVE)) {
|
|
sched_info_dequeued(rq, p);
|
|
psi_dequeue(p, flags & DEQUEUE_SLEEP);
|
|
}
|
|
|
|
uclamp_rq_dec(rq, p);
|
|
p->sched_class->dequeue_task(rq, p, flags);
|
|
}
|
|
|
|
void activate_task(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
enqueue_task(rq, p, flags);
|
|
|
|
p->on_rq = TASK_ON_RQ_QUEUED;
|
|
}
|
|
|
|
void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING;
|
|
|
|
dequeue_task(rq, p, flags);
|
|
}
|
|
|
|
/*
|
|
* __normal_prio - return the priority that is based on the static prio
|
|
*/
|
|
static inline int __normal_prio(struct task_struct *p)
|
|
{
|
|
return p->static_prio;
|
|
}
|
|
|
|
/*
|
|
* Calculate the expected normal priority: i.e. priority
|
|
* without taking RT-inheritance into account. Might be
|
|
* boosted by interactivity modifiers. Changes upon fork,
|
|
* setprio syscalls, and whenever the interactivity
|
|
* estimator recalculates.
|
|
*/
|
|
static inline int normal_prio(struct task_struct *p)
|
|
{
|
|
int prio;
|
|
|
|
if (task_has_dl_policy(p))
|
|
prio = MAX_DL_PRIO-1;
|
|
else if (task_has_rt_policy(p))
|
|
prio = MAX_RT_PRIO-1 - p->rt_priority;
|
|
else
|
|
prio = __normal_prio(p);
|
|
return prio;
|
|
}
|
|
|
|
/*
|
|
* Calculate the current priority, i.e. the priority
|
|
* taken into account by the scheduler. This value might
|
|
* be boosted by RT tasks, or might be boosted by
|
|
* interactivity modifiers. Will be RT if the task got
|
|
* RT-boosted. If not then it returns p->normal_prio.
|
|
*/
|
|
static int effective_prio(struct task_struct *p)
|
|
{
|
|
p->normal_prio = normal_prio(p);
|
|
/*
|
|
* If we are RT tasks or we were boosted to RT priority,
|
|
* keep the priority unchanged. Otherwise, update priority
|
|
* to the normal priority:
|
|
*/
|
|
if (!rt_prio(p->prio))
|
|
return p->normal_prio;
|
|
return p->prio;
|
|
}
|
|
|
|
/**
|
|
* task_curr - is this task currently executing on a CPU?
|
|
* @p: the task in question.
|
|
*
|
|
* Return: 1 if the task is currently executing. 0 otherwise.
|
|
*/
|
|
inline int task_curr(const struct task_struct *p)
|
|
{
|
|
return cpu_curr(task_cpu(p)) == p;
|
|
}
|
|
|
|
/*
|
|
* switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
|
|
* use the balance_callback list if you want balancing.
|
|
*
|
|
* this means any call to check_class_changed() must be followed by a call to
|
|
* balance_callback().
|
|
*/
|
|
static inline void check_class_changed(struct rq *rq, struct task_struct *p,
|
|
const struct sched_class *prev_class,
|
|
int oldprio)
|
|
{
|
|
if (prev_class != p->sched_class) {
|
|
if (prev_class->switched_from)
|
|
prev_class->switched_from(rq, p);
|
|
|
|
p->sched_class->switched_to(rq, p);
|
|
} else if (oldprio != p->prio || dl_task(p))
|
|
p->sched_class->prio_changed(rq, p, oldprio);
|
|
}
|
|
|
|
void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
if (p->sched_class == rq->curr->sched_class)
|
|
rq->curr->sched_class->check_preempt_curr(rq, p, flags);
|
|
else if (p->sched_class > rq->curr->sched_class)
|
|
resched_curr(rq);
|
|
|
|
/*
|
|
* A queue event has occurred, and we're going to schedule. In
|
|
* this case, we can save a useless back to back clock update.
|
|
*/
|
|
if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
|
|
rq_clock_skip_update(rq);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/*
|
|
* Per-CPU kthreads are allowed to run on !active && online CPUs, see
|
|
* __set_cpus_allowed_ptr() and select_fallback_rq().
|
|
*/
|
|
static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
|
|
{
|
|
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
|
|
return false;
|
|
|
|
if (is_per_cpu_kthread(p))
|
|
return cpu_online(cpu);
|
|
|
|
return cpu_active(cpu);
|
|
}
|
|
|
|
/*
|
|
* This is how migration works:
|
|
*
|
|
* 1) we invoke migration_cpu_stop() on the target CPU using
|
|
* stop_one_cpu().
|
|
* 2) stopper starts to run (implicitly forcing the migrated thread
|
|
* off the CPU)
|
|
* 3) it checks whether the migrated task is still in the wrong runqueue.
|
|
* 4) if it's in the wrong runqueue then the migration thread removes
|
|
* it and puts it into the right queue.
|
|
* 5) stopper completes and stop_one_cpu() returns and the migration
|
|
* is done.
|
|
*/
|
|
|
|
/*
|
|
* move_queued_task - move a queued task to new rq.
|
|
*
|
|
* Returns (locked) new rq. Old rq's lock is released.
|
|
*/
|
|
static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
|
|
struct task_struct *p, int new_cpu)
|
|
{
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
deactivate_task(rq, p, DEQUEUE_NOCLOCK);
|
|
set_task_cpu(p, new_cpu);
|
|
rq_unlock(rq, rf);
|
|
|
|
rq = cpu_rq(new_cpu);
|
|
|
|
rq_lock(rq, rf);
|
|
BUG_ON(task_cpu(p) != new_cpu);
|
|
activate_task(rq, p, 0);
|
|
check_preempt_curr(rq, p, 0);
|
|
|
|
return rq;
|
|
}
|
|
|
|
struct migration_arg {
|
|
struct task_struct *task;
|
|
int dest_cpu;
|
|
};
|
|
|
|
/*
|
|
* Move (not current) task off this CPU, onto the destination CPU. We're doing
|
|
* this because either it can't run here any more (set_cpus_allowed()
|
|
* away from this CPU, or CPU going down), or because we're
|
|
* attempting to rebalance this task on exec (sched_exec).
|
|
*
|
|
* So we race with normal scheduler movements, but that's OK, as long
|
|
* as the task is no longer on this CPU.
|
|
*/
|
|
static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
|
|
struct task_struct *p, int dest_cpu)
|
|
{
|
|
/* Affinity changed (again). */
|
|
if (!is_cpu_allowed(p, dest_cpu))
|
|
return rq;
|
|
|
|
update_rq_clock(rq);
|
|
rq = move_queued_task(rq, rf, p, dest_cpu);
|
|
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* migration_cpu_stop - this will be executed by a highprio stopper thread
|
|
* and performs thread migration by bumping thread off CPU then
|
|
* 'pushing' onto another runqueue.
|
|
*/
|
|
static int migration_cpu_stop(void *data)
|
|
{
|
|
struct migration_arg *arg = data;
|
|
struct task_struct *p = arg->task;
|
|
struct rq *rq = this_rq();
|
|
struct rq_flags rf;
|
|
|
|
/*
|
|
* The original target CPU might have gone down and we might
|
|
* be on another CPU but it doesn't matter.
|
|
*/
|
|
local_irq_disable();
|
|
/*
|
|
* We need to explicitly wake pending tasks before running
|
|
* __migrate_task() such that we will not miss enforcing cpus_ptr
|
|
* during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
|
|
*/
|
|
flush_smp_call_function_from_idle();
|
|
|
|
raw_spin_lock(&p->pi_lock);
|
|
rq_lock(rq, &rf);
|
|
/*
|
|
* If task_rq(p) != rq, it cannot be migrated here, because we're
|
|
* holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
|
|
* we're holding p->pi_lock.
|
|
*/
|
|
if (task_rq(p) == rq) {
|
|
if (task_on_rq_queued(p))
|
|
rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
|
|
else
|
|
p->wake_cpu = arg->dest_cpu;
|
|
}
|
|
rq_unlock(rq, &rf);
|
|
raw_spin_unlock(&p->pi_lock);
|
|
|
|
local_irq_enable();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* sched_class::set_cpus_allowed must do the below, but is not required to
|
|
* actually call this function.
|
|
*/
|
|
void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
|
|
{
|
|
cpumask_copy(&p->cpus_mask, new_mask);
|
|
p->nr_cpus_allowed = cpumask_weight(new_mask);
|
|
}
|
|
|
|
void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
|
|
{
|
|
struct rq *rq = task_rq(p);
|
|
bool queued, running;
|
|
|
|
lockdep_assert_held(&p->pi_lock);
|
|
|
|
queued = task_on_rq_queued(p);
|
|
running = task_current(rq, p);
|
|
|
|
if (queued) {
|
|
/*
|
|
* Because __kthread_bind() calls this on blocked tasks without
|
|
* holding rq->lock.
|
|
*/
|
|
lockdep_assert_held(&rq->lock);
|
|
dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
|
|
}
|
|
if (running)
|
|
put_prev_task(rq, p);
|
|
|
|
p->sched_class->set_cpus_allowed(p, new_mask);
|
|
|
|
if (queued)
|
|
enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
|
|
if (running)
|
|
set_next_task(rq, p);
|
|
}
|
|
|
|
/*
|
|
* Change a given task's CPU affinity. Migrate the thread to a
|
|
* proper CPU and schedule it away if the CPU it's executing on
|
|
* is removed from the allowed bitmask.
|
|
*
|
|
* NOTE: the caller must have a valid reference to the task, the
|
|
* task must not exit() & deallocate itself prematurely. The
|
|
* call is not atomic; no spinlocks may be held.
|
|
*/
|
|
static int __set_cpus_allowed_ptr(struct task_struct *p,
|
|
const struct cpumask *new_mask, bool check)
|
|
{
|
|
const struct cpumask *cpu_valid_mask = cpu_active_mask;
|
|
unsigned int dest_cpu;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
int ret = 0;
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
if (p->flags & PF_KTHREAD) {
|
|
/*
|
|
* Kernel threads are allowed on online && !active CPUs
|
|
*/
|
|
cpu_valid_mask = cpu_online_mask;
|
|
}
|
|
|
|
/*
|
|
* Must re-check here, to close a race against __kthread_bind(),
|
|
* sched_setaffinity() is not guaranteed to observe the flag.
|
|
*/
|
|
if (check && (p->flags & PF_NO_SETAFFINITY)) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
if (cpumask_equal(&p->cpus_mask, new_mask))
|
|
goto out;
|
|
|
|
/*
|
|
* Picking a ~random cpu helps in cases where we are changing affinity
|
|
* for groups of tasks (ie. cpuset), so that load balancing is not
|
|
* immediately required to distribute the tasks within their new mask.
|
|
*/
|
|
dest_cpu = cpumask_any_and_distribute(cpu_valid_mask, new_mask);
|
|
if (dest_cpu >= nr_cpu_ids) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
do_set_cpus_allowed(p, new_mask);
|
|
|
|
if (p->flags & PF_KTHREAD) {
|
|
/*
|
|
* For kernel threads that do indeed end up on online &&
|
|
* !active we want to ensure they are strict per-CPU threads.
|
|
*/
|
|
WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
|
|
!cpumask_intersects(new_mask, cpu_active_mask) &&
|
|
p->nr_cpus_allowed != 1);
|
|
}
|
|
|
|
/* Can the task run on the task's current CPU? If so, we're done */
|
|
if (cpumask_test_cpu(task_cpu(p), new_mask))
|
|
goto out;
|
|
|
|
if (task_running(rq, p) || p->state == TASK_WAKING) {
|
|
struct migration_arg arg = { p, dest_cpu };
|
|
/* Need help from migration thread: drop lock and wait. */
|
|
task_rq_unlock(rq, p, &rf);
|
|
stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
|
|
return 0;
|
|
} else if (task_on_rq_queued(p)) {
|
|
/*
|
|
* OK, since we're going to drop the lock immediately
|
|
* afterwards anyway.
|
|
*/
|
|
rq = move_queued_task(rq, &rf, p, dest_cpu);
|
|
}
|
|
out:
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
|
|
{
|
|
return __set_cpus_allowed_ptr(p, new_mask, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
|
|
|
|
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
|
|
{
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
/*
|
|
* We should never call set_task_cpu() on a blocked task,
|
|
* ttwu() will sort out the placement.
|
|
*/
|
|
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
|
|
!p->on_rq);
|
|
|
|
/*
|
|
* Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
|
|
* because schedstat_wait_{start,end} rebase migrating task's wait_start
|
|
* time relying on p->on_rq.
|
|
*/
|
|
WARN_ON_ONCE(p->state == TASK_RUNNING &&
|
|
p->sched_class == &fair_sched_class &&
|
|
(p->on_rq && !task_on_rq_migrating(p)));
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
/*
|
|
* The caller should hold either p->pi_lock or rq->lock, when changing
|
|
* a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
|
|
*
|
|
* sched_move_task() holds both and thus holding either pins the cgroup,
|
|
* see task_group().
|
|
*
|
|
* Furthermore, all task_rq users should acquire both locks, see
|
|
* task_rq_lock().
|
|
*/
|
|
WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
|
|
lockdep_is_held(&task_rq(p)->lock)));
|
|
#endif
|
|
/*
|
|
* Clearly, migrating tasks to offline CPUs is a fairly daft thing.
|
|
*/
|
|
WARN_ON_ONCE(!cpu_online(new_cpu));
|
|
#endif
|
|
|
|
trace_sched_migrate_task(p, new_cpu);
|
|
|
|
if (task_cpu(p) != new_cpu) {
|
|
if (p->sched_class->migrate_task_rq)
|
|
p->sched_class->migrate_task_rq(p, new_cpu);
|
|
p->se.nr_migrations++;
|
|
rseq_migrate(p);
|
|
perf_event_task_migrate(p);
|
|
}
|
|
|
|
__set_task_cpu(p, new_cpu);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
static void __migrate_swap_task(struct task_struct *p, int cpu)
|
|
{
|
|
if (task_on_rq_queued(p)) {
|
|
struct rq *src_rq, *dst_rq;
|
|
struct rq_flags srf, drf;
|
|
|
|
src_rq = task_rq(p);
|
|
dst_rq = cpu_rq(cpu);
|
|
|
|
rq_pin_lock(src_rq, &srf);
|
|
rq_pin_lock(dst_rq, &drf);
|
|
|
|
deactivate_task(src_rq, p, 0);
|
|
set_task_cpu(p, cpu);
|
|
activate_task(dst_rq, p, 0);
|
|
check_preempt_curr(dst_rq, p, 0);
|
|
|
|
rq_unpin_lock(dst_rq, &drf);
|
|
rq_unpin_lock(src_rq, &srf);
|
|
|
|
} else {
|
|
/*
|
|
* Task isn't running anymore; make it appear like we migrated
|
|
* it before it went to sleep. This means on wakeup we make the
|
|
* previous CPU our target instead of where it really is.
|
|
*/
|
|
p->wake_cpu = cpu;
|
|
}
|
|
}
|
|
|
|
struct migration_swap_arg {
|
|
struct task_struct *src_task, *dst_task;
|
|
int src_cpu, dst_cpu;
|
|
};
|
|
|
|
static int migrate_swap_stop(void *data)
|
|
{
|
|
struct migration_swap_arg *arg = data;
|
|
struct rq *src_rq, *dst_rq;
|
|
int ret = -EAGAIN;
|
|
|
|
if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
|
|
return -EAGAIN;
|
|
|
|
src_rq = cpu_rq(arg->src_cpu);
|
|
dst_rq = cpu_rq(arg->dst_cpu);
|
|
|
|
double_raw_lock(&arg->src_task->pi_lock,
|
|
&arg->dst_task->pi_lock);
|
|
double_rq_lock(src_rq, dst_rq);
|
|
|
|
if (task_cpu(arg->dst_task) != arg->dst_cpu)
|
|
goto unlock;
|
|
|
|
if (task_cpu(arg->src_task) != arg->src_cpu)
|
|
goto unlock;
|
|
|
|
if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr))
|
|
goto unlock;
|
|
|
|
if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr))
|
|
goto unlock;
|
|
|
|
__migrate_swap_task(arg->src_task, arg->dst_cpu);
|
|
__migrate_swap_task(arg->dst_task, arg->src_cpu);
|
|
|
|
ret = 0;
|
|
|
|
unlock:
|
|
double_rq_unlock(src_rq, dst_rq);
|
|
raw_spin_unlock(&arg->dst_task->pi_lock);
|
|
raw_spin_unlock(&arg->src_task->pi_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Cross migrate two tasks
|
|
*/
|
|
int migrate_swap(struct task_struct *cur, struct task_struct *p,
|
|
int target_cpu, int curr_cpu)
|
|
{
|
|
struct migration_swap_arg arg;
|
|
int ret = -EINVAL;
|
|
|
|
arg = (struct migration_swap_arg){
|
|
.src_task = cur,
|
|
.src_cpu = curr_cpu,
|
|
.dst_task = p,
|
|
.dst_cpu = target_cpu,
|
|
};
|
|
|
|
if (arg.src_cpu == arg.dst_cpu)
|
|
goto out;
|
|
|
|
/*
|
|
* These three tests are all lockless; this is OK since all of them
|
|
* will be re-checked with proper locks held further down the line.
|
|
*/
|
|
if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
|
|
goto out;
|
|
|
|
if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr))
|
|
goto out;
|
|
|
|
if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr))
|
|
goto out;
|
|
|
|
trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
|
|
ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
/*
|
|
* wait_task_inactive - wait for a thread to unschedule.
|
|
*
|
|
* If @match_state is nonzero, it's the @p->state value just checked and
|
|
* not expected to change. If it changes, i.e. @p might have woken up,
|
|
* then return zero. When we succeed in waiting for @p to be off its CPU,
|
|
* we return a positive number (its total switch count). If a second call
|
|
* a short while later returns the same number, the caller can be sure that
|
|
* @p has remained unscheduled the whole time.
|
|
*
|
|
* The caller must ensure that the task *will* unschedule sometime soon,
|
|
* else this function might spin for a *long* time. This function can't
|
|
* be called with interrupts off, or it may introduce deadlock with
|
|
* smp_call_function() if an IPI is sent by the same process we are
|
|
* waiting to become inactive.
|
|
*/
|
|
unsigned long wait_task_inactive(struct task_struct *p, long match_state)
|
|
{
|
|
int running, queued;
|
|
struct rq_flags rf;
|
|
unsigned long ncsw;
|
|
struct rq *rq;
|
|
|
|
for (;;) {
|
|
/*
|
|
* We do the initial early heuristics without holding
|
|
* any task-queue locks at all. We'll only try to get
|
|
* the runqueue lock when things look like they will
|
|
* work out!
|
|
*/
|
|
rq = task_rq(p);
|
|
|
|
/*
|
|
* If the task is actively running on another CPU
|
|
* still, just relax and busy-wait without holding
|
|
* any locks.
|
|
*
|
|
* NOTE! Since we don't hold any locks, it's not
|
|
* even sure that "rq" stays as the right runqueue!
|
|
* But we don't care, since "task_running()" will
|
|
* return false if the runqueue has changed and p
|
|
* is actually now running somewhere else!
|
|
*/
|
|
while (task_running(rq, p)) {
|
|
if (match_state && unlikely(p->state != match_state))
|
|
return 0;
|
|
cpu_relax();
|
|
}
|
|
|
|
/*
|
|
* Ok, time to look more closely! We need the rq
|
|
* lock now, to be *sure*. If we're wrong, we'll
|
|
* just go back and repeat.
|
|
*/
|
|
rq = task_rq_lock(p, &rf);
|
|
trace_sched_wait_task(p);
|
|
running = task_running(rq, p);
|
|
queued = task_on_rq_queued(p);
|
|
ncsw = 0;
|
|
if (!match_state || p->state == match_state)
|
|
ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
/*
|
|
* If it changed from the expected state, bail out now.
|
|
*/
|
|
if (unlikely(!ncsw))
|
|
break;
|
|
|
|
/*
|
|
* Was it really running after all now that we
|
|
* checked with the proper locks actually held?
|
|
*
|
|
* Oops. Go back and try again..
|
|
*/
|
|
if (unlikely(running)) {
|
|
cpu_relax();
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* It's not enough that it's not actively running,
|
|
* it must be off the runqueue _entirely_, and not
|
|
* preempted!
|
|
*
|
|
* So if it was still runnable (but just not actively
|
|
* running right now), it's preempted, and we should
|
|
* yield - it could be a while.
|
|
*/
|
|
if (unlikely(queued)) {
|
|
ktime_t to = NSEC_PER_SEC / HZ;
|
|
|
|
set_current_state(TASK_UNINTERRUPTIBLE);
|
|
schedule_hrtimeout(&to, HRTIMER_MODE_REL);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Ahh, all good. It wasn't running, and it wasn't
|
|
* runnable, which means that it will never become
|
|
* running in the future either. We're all done!
|
|
*/
|
|
break;
|
|
}
|
|
|
|
return ncsw;
|
|
}
|
|
|
|
/***
|
|
* kick_process - kick a running thread to enter/exit the kernel
|
|
* @p: the to-be-kicked thread
|
|
*
|
|
* Cause a process which is running on another CPU to enter
|
|
* kernel-mode, without any delay. (to get signals handled.)
|
|
*
|
|
* NOTE: this function doesn't have to take the runqueue lock,
|
|
* because all it wants to ensure is that the remote task enters
|
|
* the kernel. If the IPI races and the task has been migrated
|
|
* to another CPU then no harm is done and the purpose has been
|
|
* achieved as well.
|
|
*/
|
|
void kick_process(struct task_struct *p)
|
|
{
|
|
int cpu;
|
|
|
|
preempt_disable();
|
|
cpu = task_cpu(p);
|
|
if ((cpu != smp_processor_id()) && task_curr(p))
|
|
smp_send_reschedule(cpu);
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL_GPL(kick_process);
|
|
|
|
/*
|
|
* ->cpus_ptr is protected by both rq->lock and p->pi_lock
|
|
*
|
|
* A few notes on cpu_active vs cpu_online:
|
|
*
|
|
* - cpu_active must be a subset of cpu_online
|
|
*
|
|
* - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
|
|
* see __set_cpus_allowed_ptr(). At this point the newly online
|
|
* CPU isn't yet part of the sched domains, and balancing will not
|
|
* see it.
|
|
*
|
|
* - on CPU-down we clear cpu_active() to mask the sched domains and
|
|
* avoid the load balancer to place new tasks on the to be removed
|
|
* CPU. Existing tasks will remain running there and will be taken
|
|
* off.
|
|
*
|
|
* This means that fallback selection must not select !active CPUs.
|
|
* And can assume that any active CPU must be online. Conversely
|
|
* select_task_rq() below may allow selection of !active CPUs in order
|
|
* to satisfy the above rules.
|
|
*/
|
|
static int select_fallback_rq(int cpu, struct task_struct *p)
|
|
{
|
|
int nid = cpu_to_node(cpu);
|
|
const struct cpumask *nodemask = NULL;
|
|
enum { cpuset, possible, fail } state = cpuset;
|
|
int dest_cpu;
|
|
|
|
/*
|
|
* If the node that the CPU is on has been offlined, cpu_to_node()
|
|
* will return -1. There is no CPU on the node, and we should
|
|
* select the CPU on the other node.
|
|
*/
|
|
if (nid != -1) {
|
|
nodemask = cpumask_of_node(nid);
|
|
|
|
/* Look for allowed, online CPU in same node. */
|
|
for_each_cpu(dest_cpu, nodemask) {
|
|
if (!cpu_active(dest_cpu))
|
|
continue;
|
|
if (cpumask_test_cpu(dest_cpu, p->cpus_ptr))
|
|
return dest_cpu;
|
|
}
|
|
}
|
|
|
|
for (;;) {
|
|
/* Any allowed, online CPU? */
|
|
for_each_cpu(dest_cpu, p->cpus_ptr) {
|
|
if (!is_cpu_allowed(p, dest_cpu))
|
|
continue;
|
|
|
|
goto out;
|
|
}
|
|
|
|
/* No more Mr. Nice Guy. */
|
|
switch (state) {
|
|
case cpuset:
|
|
if (IS_ENABLED(CONFIG_CPUSETS)) {
|
|
cpuset_cpus_allowed_fallback(p);
|
|
state = possible;
|
|
break;
|
|
}
|
|
fallthrough;
|
|
case possible:
|
|
do_set_cpus_allowed(p, cpu_possible_mask);
|
|
state = fail;
|
|
break;
|
|
|
|
case fail:
|
|
BUG();
|
|
break;
|
|
}
|
|
}
|
|
|
|
out:
|
|
if (state != cpuset) {
|
|
/*
|
|
* Don't tell them about moving exiting tasks or
|
|
* kernel threads (both mm NULL), since they never
|
|
* leave kernel.
|
|
*/
|
|
if (p->mm && printk_ratelimit()) {
|
|
printk_deferred("process %d (%s) no longer affine to cpu%d\n",
|
|
task_pid_nr(p), p->comm, cpu);
|
|
}
|
|
}
|
|
|
|
return dest_cpu;
|
|
}
|
|
|
|
/*
|
|
* The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.
|
|
*/
|
|
static inline
|
|
int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
|
|
{
|
|
lockdep_assert_held(&p->pi_lock);
|
|
|
|
if (p->nr_cpus_allowed > 1)
|
|
cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
|
|
else
|
|
cpu = cpumask_any(p->cpus_ptr);
|
|
|
|
/*
|
|
* In order not to call set_task_cpu() on a blocking task we need
|
|
* to rely on ttwu() to place the task on a valid ->cpus_ptr
|
|
* CPU.
|
|
*
|
|
* Since this is common to all placement strategies, this lives here.
|
|
*
|
|
* [ this allows ->select_task() to simply return task_cpu(p) and
|
|
* not worry about this generic constraint ]
|
|
*/
|
|
if (unlikely(!is_cpu_allowed(p, cpu)))
|
|
cpu = select_fallback_rq(task_cpu(p), p);
|
|
|
|
return cpu;
|
|
}
|
|
|
|
void sched_set_stop_task(int cpu, struct task_struct *stop)
|
|
{
|
|
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
|
|
struct task_struct *old_stop = cpu_rq(cpu)->stop;
|
|
|
|
if (stop) {
|
|
/*
|
|
* Make it appear like a SCHED_FIFO task, its something
|
|
* userspace knows about and won't get confused about.
|
|
*
|
|
* Also, it will make PI more or less work without too
|
|
* much confusion -- but then, stop work should not
|
|
* rely on PI working anyway.
|
|
*/
|
|
sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
|
|
|
|
stop->sched_class = &stop_sched_class;
|
|
}
|
|
|
|
cpu_rq(cpu)->stop = stop;
|
|
|
|
if (old_stop) {
|
|
/*
|
|
* Reset it back to a normal scheduling class so that
|
|
* it can die in pieces.
|
|
*/
|
|
old_stop->sched_class = &rt_sched_class;
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline int __set_cpus_allowed_ptr(struct task_struct *p,
|
|
const struct cpumask *new_mask, bool check)
|
|
{
|
|
return set_cpus_allowed_ptr(p, new_mask);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void
|
|
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
|
|
{
|
|
struct rq *rq;
|
|
|
|
if (!schedstat_enabled())
|
|
return;
|
|
|
|
rq = this_rq();
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (cpu == rq->cpu) {
|
|
__schedstat_inc(rq->ttwu_local);
|
|
__schedstat_inc(p->se.statistics.nr_wakeups_local);
|
|
} else {
|
|
struct sched_domain *sd;
|
|
|
|
__schedstat_inc(p->se.statistics.nr_wakeups_remote);
|
|
rcu_read_lock();
|
|
for_each_domain(rq->cpu, sd) {
|
|
if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
|
|
__schedstat_inc(sd->ttwu_wake_remote);
|
|
break;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
if (wake_flags & WF_MIGRATED)
|
|
__schedstat_inc(p->se.statistics.nr_wakeups_migrate);
|
|
#endif /* CONFIG_SMP */
|
|
|
|
__schedstat_inc(rq->ttwu_count);
|
|
__schedstat_inc(p->se.statistics.nr_wakeups);
|
|
|
|
if (wake_flags & WF_SYNC)
|
|
__schedstat_inc(p->se.statistics.nr_wakeups_sync);
|
|
}
|
|
|
|
/*
|
|
* Mark the task runnable and perform wakeup-preemption.
|
|
*/
|
|
static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
|
|
struct rq_flags *rf)
|
|
{
|
|
check_preempt_curr(rq, p, wake_flags);
|
|
p->state = TASK_RUNNING;
|
|
trace_sched_wakeup(p);
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (p->sched_class->task_woken) {
|
|
/*
|
|
* Our task @p is fully woken up and running; so its safe to
|
|
* drop the rq->lock, hereafter rq is only used for statistics.
|
|
*/
|
|
rq_unpin_lock(rq, rf);
|
|
p->sched_class->task_woken(rq, p);
|
|
rq_repin_lock(rq, rf);
|
|
}
|
|
|
|
if (rq->idle_stamp) {
|
|
u64 delta = rq_clock(rq) - rq->idle_stamp;
|
|
u64 max = 2*rq->max_idle_balance_cost;
|
|
|
|
update_avg(&rq->avg_idle, delta);
|
|
|
|
if (rq->avg_idle > max)
|
|
rq->avg_idle = max;
|
|
|
|
rq->idle_stamp = 0;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
|
|
struct rq_flags *rf)
|
|
{
|
|
int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
|
|
|
|
lockdep_assert_held(&rq->lock);
|
|
|
|
if (p->sched_contributes_to_load)
|
|
rq->nr_uninterruptible--;
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (wake_flags & WF_MIGRATED)
|
|
en_flags |= ENQUEUE_MIGRATED;
|
|
else
|
|
#endif
|
|
if (p->in_iowait) {
|
|
delayacct_blkio_end(p);
|
|
atomic_dec(&task_rq(p)->nr_iowait);
|
|
}
|
|
|
|
activate_task(rq, p, en_flags);
|
|
ttwu_do_wakeup(rq, p, wake_flags, rf);
|
|
}
|
|
|
|
/*
|
|
* Consider @p being inside a wait loop:
|
|
*
|
|
* for (;;) {
|
|
* set_current_state(TASK_UNINTERRUPTIBLE);
|
|
*
|
|
* if (CONDITION)
|
|
* break;
|
|
*
|
|
* schedule();
|
|
* }
|
|
* __set_current_state(TASK_RUNNING);
|
|
*
|
|
* between set_current_state() and schedule(). In this case @p is still
|
|
* runnable, so all that needs doing is change p->state back to TASK_RUNNING in
|
|
* an atomic manner.
|
|
*
|
|
* By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq
|
|
* then schedule() must still happen and p->state can be changed to
|
|
* TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we
|
|
* need to do a full wakeup with enqueue.
|
|
*
|
|
* Returns: %true when the wakeup is done,
|
|
* %false otherwise.
|
|
*/
|
|
static int ttwu_runnable(struct task_struct *p, int wake_flags)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
int ret = 0;
|
|
|
|
rq = __task_rq_lock(p, &rf);
|
|
if (task_on_rq_queued(p)) {
|
|
/* check_preempt_curr() may use rq clock */
|
|
update_rq_clock(rq);
|
|
ttwu_do_wakeup(rq, p, wake_flags, &rf);
|
|
ret = 1;
|
|
}
|
|
__task_rq_unlock(rq, &rf);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
void sched_ttwu_pending(void *arg)
|
|
{
|
|
struct llist_node *llist = arg;
|
|
struct rq *rq = this_rq();
|
|
struct task_struct *p, *t;
|
|
struct rq_flags rf;
|
|
|
|
if (!llist)
|
|
return;
|
|
|
|
/*
|
|
* rq::ttwu_pending racy indication of out-standing wakeups.
|
|
* Races such that false-negatives are possible, since they
|
|
* are shorter lived that false-positives would be.
|
|
*/
|
|
WRITE_ONCE(rq->ttwu_pending, 0);
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
|
|
if (WARN_ON_ONCE(p->on_cpu))
|
|
smp_cond_load_acquire(&p->on_cpu, !VAL);
|
|
|
|
if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
|
|
set_task_cpu(p, cpu_of(rq));
|
|
|
|
ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
|
|
}
|
|
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
void send_call_function_single_ipi(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (!set_nr_if_polling(rq->idle))
|
|
arch_send_call_function_single_ipi(cpu);
|
|
else
|
|
trace_sched_wake_idle_without_ipi(cpu);
|
|
}
|
|
|
|
/*
|
|
* Queue a task on the target CPUs wake_list and wake the CPU via IPI if
|
|
* necessary. The wakee CPU on receipt of the IPI will queue the task
|
|
* via sched_ttwu_wakeup() for activation so the wakee incurs the cost
|
|
* of the wakeup instead of the waker.
|
|
*/
|
|
static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
|
|
|
|
WRITE_ONCE(rq->ttwu_pending, 1);
|
|
__smp_call_single_queue(cpu, &p->wake_entry.llist);
|
|
}
|
|
|
|
void wake_up_if_idle(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct rq_flags rf;
|
|
|
|
rcu_read_lock();
|
|
|
|
if (!is_idle_task(rcu_dereference(rq->curr)))
|
|
goto out;
|
|
|
|
if (set_nr_if_polling(rq->idle)) {
|
|
trace_sched_wake_idle_without_ipi(cpu);
|
|
} else {
|
|
rq_lock_irqsave(rq, &rf);
|
|
if (is_idle_task(rq->curr))
|
|
smp_send_reschedule(cpu);
|
|
/* Else CPU is not idle, do nothing here: */
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
}
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
bool cpus_share_cache(int this_cpu, int that_cpu)
|
|
{
|
|
return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
|
|
}
|
|
|
|
static inline bool ttwu_queue_cond(int cpu, int wake_flags)
|
|
{
|
|
/*
|
|
* If the CPU does not share cache, then queue the task on the
|
|
* remote rqs wakelist to avoid accessing remote data.
|
|
*/
|
|
if (!cpus_share_cache(smp_processor_id(), cpu))
|
|
return true;
|
|
|
|
/*
|
|
* If the task is descheduling and the only running task on the
|
|
* CPU then use the wakelist to offload the task activation to
|
|
* the soon-to-be-idle CPU as the current CPU is likely busy.
|
|
* nr_running is checked to avoid unnecessary task stacking.
|
|
*/
|
|
if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
|
|
{
|
|
if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
|
|
if (WARN_ON_ONCE(cpu == smp_processor_id()))
|
|
return false;
|
|
|
|
sched_clock_cpu(cpu); /* Sync clocks across CPUs */
|
|
__ttwu_queue_wakelist(p, cpu, wake_flags);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
#else /* !CONFIG_SMP */
|
|
|
|
static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct rq_flags rf;
|
|
|
|
if (ttwu_queue_wakelist(p, cpu, wake_flags))
|
|
return;
|
|
|
|
rq_lock(rq, &rf);
|
|
update_rq_clock(rq);
|
|
ttwu_do_activate(rq, p, wake_flags, &rf);
|
|
rq_unlock(rq, &rf);
|
|
}
|
|
|
|
/*
|
|
* Notes on Program-Order guarantees on SMP systems.
|
|
*
|
|
* MIGRATION
|
|
*
|
|
* The basic program-order guarantee on SMP systems is that when a task [t]
|
|
* migrates, all its activity on its old CPU [c0] happens-before any subsequent
|
|
* execution on its new CPU [c1].
|
|
*
|
|
* For migration (of runnable tasks) this is provided by the following means:
|
|
*
|
|
* A) UNLOCK of the rq(c0)->lock scheduling out task t
|
|
* B) migration for t is required to synchronize *both* rq(c0)->lock and
|
|
* rq(c1)->lock (if not at the same time, then in that order).
|
|
* C) LOCK of the rq(c1)->lock scheduling in task
|
|
*
|
|
* Release/acquire chaining guarantees that B happens after A and C after B.
|
|
* Note: the CPU doing B need not be c0 or c1
|
|
*
|
|
* Example:
|
|
*
|
|
* CPU0 CPU1 CPU2
|
|
*
|
|
* LOCK rq(0)->lock
|
|
* sched-out X
|
|
* sched-in Y
|
|
* UNLOCK rq(0)->lock
|
|
*
|
|
* LOCK rq(0)->lock // orders against CPU0
|
|
* dequeue X
|
|
* UNLOCK rq(0)->lock
|
|
*
|
|
* LOCK rq(1)->lock
|
|
* enqueue X
|
|
* UNLOCK rq(1)->lock
|
|
*
|
|
* LOCK rq(1)->lock // orders against CPU2
|
|
* sched-out Z
|
|
* sched-in X
|
|
* UNLOCK rq(1)->lock
|
|
*
|
|
*
|
|
* BLOCKING -- aka. SLEEP + WAKEUP
|
|
*
|
|
* For blocking we (obviously) need to provide the same guarantee as for
|
|
* migration. However the means are completely different as there is no lock
|
|
* chain to provide order. Instead we do:
|
|
*
|
|
* 1) smp_store_release(X->on_cpu, 0) -- finish_task()
|
|
* 2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up()
|
|
*
|
|
* Example:
|
|
*
|
|
* CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
|
|
*
|
|
* LOCK rq(0)->lock LOCK X->pi_lock
|
|
* dequeue X
|
|
* sched-out X
|
|
* smp_store_release(X->on_cpu, 0);
|
|
*
|
|
* smp_cond_load_acquire(&X->on_cpu, !VAL);
|
|
* X->state = WAKING
|
|
* set_task_cpu(X,2)
|
|
*
|
|
* LOCK rq(2)->lock
|
|
* enqueue X
|
|
* X->state = RUNNING
|
|
* UNLOCK rq(2)->lock
|
|
*
|
|
* LOCK rq(2)->lock // orders against CPU1
|
|
* sched-out Z
|
|
* sched-in X
|
|
* UNLOCK rq(2)->lock
|
|
*
|
|
* UNLOCK X->pi_lock
|
|
* UNLOCK rq(0)->lock
|
|
*
|
|
*
|
|
* However, for wakeups there is a second guarantee we must provide, namely we
|
|
* must ensure that CONDITION=1 done by the caller can not be reordered with
|
|
* accesses to the task state; see try_to_wake_up() and set_current_state().
|
|
*/
|
|
|
|
/**
|
|
* try_to_wake_up - wake up a thread
|
|
* @p: the thread to be awakened
|
|
* @state: the mask of task states that can be woken
|
|
* @wake_flags: wake modifier flags (WF_*)
|
|
*
|
|
* Conceptually does:
|
|
*
|
|
* If (@state & @p->state) @p->state = TASK_RUNNING.
|
|
*
|
|
* If the task was not queued/runnable, also place it back on a runqueue.
|
|
*
|
|
* This function is atomic against schedule() which would dequeue the task.
|
|
*
|
|
* It issues a full memory barrier before accessing @p->state, see the comment
|
|
* with set_current_state().
|
|
*
|
|
* Uses p->pi_lock to serialize against concurrent wake-ups.
|
|
*
|
|
* Relies on p->pi_lock stabilizing:
|
|
* - p->sched_class
|
|
* - p->cpus_ptr
|
|
* - p->sched_task_group
|
|
* in order to do migration, see its use of select_task_rq()/set_task_cpu().
|
|
*
|
|
* Tries really hard to only take one task_rq(p)->lock for performance.
|
|
* Takes rq->lock in:
|
|
* - ttwu_runnable() -- old rq, unavoidable, see comment there;
|
|
* - ttwu_queue() -- new rq, for enqueue of the task;
|
|
* - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us.
|
|
*
|
|
* As a consequence we race really badly with just about everything. See the
|
|
* many memory barriers and their comments for details.
|
|
*
|
|
* Return: %true if @p->state changes (an actual wakeup was done),
|
|
* %false otherwise.
|
|
*/
|
|
static int
|
|
try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
|
|
{
|
|
unsigned long flags;
|
|
int cpu, success = 0;
|
|
|
|
preempt_disable();
|
|
if (p == current) {
|
|
/*
|
|
* We're waking current, this means 'p->on_rq' and 'task_cpu(p)
|
|
* == smp_processor_id()'. Together this means we can special
|
|
* case the whole 'p->on_rq && ttwu_runnable()' case below
|
|
* without taking any locks.
|
|
*
|
|
* In particular:
|
|
* - we rely on Program-Order guarantees for all the ordering,
|
|
* - we're serialized against set_special_state() by virtue of
|
|
* it disabling IRQs (this allows not taking ->pi_lock).
|
|
*/
|
|
if (!(p->state & state))
|
|
goto out;
|
|
|
|
success = 1;
|
|
trace_sched_waking(p);
|
|
p->state = TASK_RUNNING;
|
|
trace_sched_wakeup(p);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* If we are going to wake up a thread waiting for CONDITION we
|
|
* need to ensure that CONDITION=1 done by the caller can not be
|
|
* reordered with p->state check below. This pairs with smp_store_mb()
|
|
* in set_current_state() that the waiting thread does.
|
|
*/
|
|
raw_spin_lock_irqsave(&p->pi_lock, flags);
|
|
smp_mb__after_spinlock();
|
|
if (!(p->state & state))
|
|
goto unlock;
|
|
|
|
trace_sched_waking(p);
|
|
|
|
/* We're going to change ->state: */
|
|
success = 1;
|
|
|
|
/*
|
|
* Ensure we load p->on_rq _after_ p->state, otherwise it would
|
|
* be possible to, falsely, observe p->on_rq == 0 and get stuck
|
|
* in smp_cond_load_acquire() below.
|
|
*
|
|
* sched_ttwu_pending() try_to_wake_up()
|
|
* STORE p->on_rq = 1 LOAD p->state
|
|
* UNLOCK rq->lock
|
|
*
|
|
* __schedule() (switch to task 'p')
|
|
* LOCK rq->lock smp_rmb();
|
|
* smp_mb__after_spinlock();
|
|
* UNLOCK rq->lock
|
|
*
|
|
* [task p]
|
|
* STORE p->state = UNINTERRUPTIBLE LOAD p->on_rq
|
|
*
|
|
* Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
|
|
* __schedule(). See the comment for smp_mb__after_spinlock().
|
|
*
|
|
* A similar smb_rmb() lives in try_invoke_on_locked_down_task().
|
|
*/
|
|
smp_rmb();
|
|
if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))
|
|
goto unlock;
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
|
|
* possible to, falsely, observe p->on_cpu == 0.
|
|
*
|
|
* One must be running (->on_cpu == 1) in order to remove oneself
|
|
* from the runqueue.
|
|
*
|
|
* __schedule() (switch to task 'p') try_to_wake_up()
|
|
* STORE p->on_cpu = 1 LOAD p->on_rq
|
|
* UNLOCK rq->lock
|
|
*
|
|
* __schedule() (put 'p' to sleep)
|
|
* LOCK rq->lock smp_rmb();
|
|
* smp_mb__after_spinlock();
|
|
* STORE p->on_rq = 0 LOAD p->on_cpu
|
|
*
|
|
* Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
|
|
* __schedule(). See the comment for smp_mb__after_spinlock().
|
|
*
|
|
* Form a control-dep-acquire with p->on_rq == 0 above, to ensure
|
|
* schedule()'s deactivate_task() has 'happened' and p will no longer
|
|
* care about it's own p->state. See the comment in __schedule().
|
|
*/
|
|
smp_acquire__after_ctrl_dep();
|
|
|
|
/*
|
|
* We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq
|
|
* == 0), which means we need to do an enqueue, change p->state to
|
|
* TASK_WAKING such that we can unlock p->pi_lock before doing the
|
|
* enqueue, such as ttwu_queue_wakelist().
|
|
*/
|
|
p->state = TASK_WAKING;
|
|
|
|
/*
|
|
* If the owning (remote) CPU is still in the middle of schedule() with
|
|
* this task as prev, considering queueing p on the remote CPUs wake_list
|
|
* which potentially sends an IPI instead of spinning on p->on_cpu to
|
|
* let the waker make forward progress. This is safe because IRQs are
|
|
* disabled and the IPI will deliver after on_cpu is cleared.
|
|
*
|
|
* Ensure we load task_cpu(p) after p->on_cpu:
|
|
*
|
|
* set_task_cpu(p, cpu);
|
|
* STORE p->cpu = @cpu
|
|
* __schedule() (switch to task 'p')
|
|
* LOCK rq->lock
|
|
* smp_mb__after_spin_lock() smp_cond_load_acquire(&p->on_cpu)
|
|
* STORE p->on_cpu = 1 LOAD p->cpu
|
|
*
|
|
* to ensure we observe the correct CPU on which the task is currently
|
|
* scheduling.
|
|
*/
|
|
if (smp_load_acquire(&p->on_cpu) &&
|
|
ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
|
|
goto unlock;
|
|
|
|
/*
|
|
* If the owning (remote) CPU is still in the middle of schedule() with
|
|
* this task as prev, wait until its done referencing the task.
|
|
*
|
|
* Pairs with the smp_store_release() in finish_task().
|
|
*
|
|
* This ensures that tasks getting woken will be fully ordered against
|
|
* their previous state and preserve Program Order.
|
|
*/
|
|
smp_cond_load_acquire(&p->on_cpu, !VAL);
|
|
|
|
cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
|
|
if (task_cpu(p) != cpu) {
|
|
if (p->in_iowait) {
|
|
delayacct_blkio_end(p);
|
|
atomic_dec(&task_rq(p)->nr_iowait);
|
|
}
|
|
|
|
wake_flags |= WF_MIGRATED;
|
|
psi_ttwu_dequeue(p);
|
|
set_task_cpu(p, cpu);
|
|
}
|
|
#else
|
|
cpu = task_cpu(p);
|
|
#endif /* CONFIG_SMP */
|
|
|
|
ttwu_queue(p, cpu, wake_flags);
|
|
unlock:
|
|
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
out:
|
|
if (success)
|
|
ttwu_stat(p, task_cpu(p), wake_flags);
|
|
preempt_enable();
|
|
|
|
return success;
|
|
}
|
|
|
|
/**
|
|
* try_invoke_on_locked_down_task - Invoke a function on task in fixed state
|
|
* @p: Process for which the function is to be invoked.
|
|
* @func: Function to invoke.
|
|
* @arg: Argument to function.
|
|
*
|
|
* If the specified task can be quickly locked into a definite state
|
|
* (either sleeping or on a given runqueue), arrange to keep it in that
|
|
* state while invoking @func(@arg). This function can use ->on_rq and
|
|
* task_curr() to work out what the state is, if required. Given that
|
|
* @func can be invoked with a runqueue lock held, it had better be quite
|
|
* lightweight.
|
|
*
|
|
* Returns:
|
|
* @false if the task slipped out from under the locks.
|
|
* @true if the task was locked onto a runqueue or is sleeping.
|
|
* However, @func can override this by returning @false.
|
|
*/
|
|
bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
|
|
{
|
|
bool ret = false;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
lockdep_assert_irqs_enabled();
|
|
raw_spin_lock_irq(&p->pi_lock);
|
|
if (p->on_rq) {
|
|
rq = __task_rq_lock(p, &rf);
|
|
if (task_rq(p) == rq)
|
|
ret = func(p, arg);
|
|
rq_unlock(rq, &rf);
|
|
} else {
|
|
switch (p->state) {
|
|
case TASK_RUNNING:
|
|
case TASK_WAKING:
|
|
break;
|
|
default:
|
|
smp_rmb(); // See smp_rmb() comment in try_to_wake_up().
|
|
if (!p->on_rq)
|
|
ret = func(p, arg);
|
|
}
|
|
}
|
|
raw_spin_unlock_irq(&p->pi_lock);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* wake_up_process - Wake up a specific process
|
|
* @p: The process to be woken up.
|
|
*
|
|
* Attempt to wake up the nominated process and move it to the set of runnable
|
|
* processes.
|
|
*
|
|
* Return: 1 if the process was woken up, 0 if it was already running.
|
|
*
|
|
* This function executes a full memory barrier before accessing the task state.
|
|
*/
|
|
int wake_up_process(struct task_struct *p)
|
|
{
|
|
return try_to_wake_up(p, TASK_NORMAL, 0);
|
|
}
|
|
EXPORT_SYMBOL(wake_up_process);
|
|
|
|
int wake_up_state(struct task_struct *p, unsigned int state)
|
|
{
|
|
return try_to_wake_up(p, state, 0);
|
|
}
|
|
|
|
/*
|
|
* Perform scheduler related setup for a newly forked process p.
|
|
* p is forked by current.
|
|
*
|
|
* __sched_fork() is basic setup used by init_idle() too:
|
|
*/
|
|
static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
p->on_rq = 0;
|
|
|
|
p->se.on_rq = 0;
|
|
p->se.exec_start = 0;
|
|
p->se.sum_exec_runtime = 0;
|
|
p->se.prev_sum_exec_runtime = 0;
|
|
p->se.nr_migrations = 0;
|
|
p->se.vruntime = 0;
|
|
INIT_LIST_HEAD(&p->se.group_node);
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
p->se.cfs_rq = NULL;
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
/* Even if schedstat is disabled, there should not be garbage */
|
|
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
|
|
#endif
|
|
|
|
RB_CLEAR_NODE(&p->dl.rb_node);
|
|
init_dl_task_timer(&p->dl);
|
|
init_dl_inactive_task_timer(&p->dl);
|
|
__dl_clear_params(p);
|
|
|
|
INIT_LIST_HEAD(&p->rt.run_list);
|
|
p->rt.timeout = 0;
|
|
p->rt.time_slice = sched_rr_timeslice;
|
|
p->rt.on_rq = 0;
|
|
p->rt.on_list = 0;
|
|
|
|
#ifdef CONFIG_PREEMPT_NOTIFIERS
|
|
INIT_HLIST_HEAD(&p->preempt_notifiers);
|
|
#endif
|
|
|
|
#ifdef CONFIG_COMPACTION
|
|
p->capture_control = NULL;
|
|
#endif
|
|
init_numa_balancing(clone_flags, p);
|
|
#ifdef CONFIG_SMP
|
|
p->wake_entry.u_flags = CSD_TYPE_TTWU;
|
|
#endif
|
|
}
|
|
|
|
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
|
|
void set_numabalancing_state(bool enabled)
|
|
{
|
|
if (enabled)
|
|
static_branch_enable(&sched_numa_balancing);
|
|
else
|
|
static_branch_disable(&sched_numa_balancing);
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_SYSCTL
|
|
int sysctl_numa_balancing(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table t;
|
|
int err;
|
|
int state = static_branch_likely(&sched_numa_balancing);
|
|
|
|
if (write && !capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
t = *table;
|
|
t.data = &state;
|
|
err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
|
if (err < 0)
|
|
return err;
|
|
if (write)
|
|
set_numabalancing_state(state);
|
|
return err;
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
|
|
DEFINE_STATIC_KEY_FALSE(sched_schedstats);
|
|
static bool __initdata __sched_schedstats = false;
|
|
|
|
static void set_schedstats(bool enabled)
|
|
{
|
|
if (enabled)
|
|
static_branch_enable(&sched_schedstats);
|
|
else
|
|
static_branch_disable(&sched_schedstats);
|
|
}
|
|
|
|
void force_schedstat_enabled(void)
|
|
{
|
|
if (!schedstat_enabled()) {
|
|
pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
|
|
static_branch_enable(&sched_schedstats);
|
|
}
|
|
}
|
|
|
|
static int __init setup_schedstats(char *str)
|
|
{
|
|
int ret = 0;
|
|
if (!str)
|
|
goto out;
|
|
|
|
/*
|
|
* This code is called before jump labels have been set up, so we can't
|
|
* change the static branch directly just yet. Instead set a temporary
|
|
* variable so init_schedstats() can do it later.
|
|
*/
|
|
if (!strcmp(str, "enable")) {
|
|
__sched_schedstats = true;
|
|
ret = 1;
|
|
} else if (!strcmp(str, "disable")) {
|
|
__sched_schedstats = false;
|
|
ret = 1;
|
|
}
|
|
out:
|
|
if (!ret)
|
|
pr_warn("Unable to parse schedstats=\n");
|
|
|
|
return ret;
|
|
}
|
|
__setup("schedstats=", setup_schedstats);
|
|
|
|
static void __init init_schedstats(void)
|
|
{
|
|
set_schedstats(__sched_schedstats);
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_SYSCTL
|
|
int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table t;
|
|
int err;
|
|
int state = static_branch_likely(&sched_schedstats);
|
|
|
|
if (write && !capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
t = *table;
|
|
t.data = &state;
|
|
err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
|
if (err < 0)
|
|
return err;
|
|
if (write)
|
|
set_schedstats(state);
|
|
return err;
|
|
}
|
|
#endif /* CONFIG_PROC_SYSCTL */
|
|
#else /* !CONFIG_SCHEDSTATS */
|
|
static inline void init_schedstats(void) {}
|
|
#endif /* CONFIG_SCHEDSTATS */
|
|
|
|
/*
|
|
* fork()/clone()-time setup:
|
|
*/
|
|
int sched_fork(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
unsigned long flags;
|
|
|
|
__sched_fork(clone_flags, p);
|
|
/*
|
|
* We mark the process as NEW here. This guarantees that
|
|
* nobody will actually run it, and a signal or other external
|
|
* event cannot wake it up and insert it on the runqueue either.
|
|
*/
|
|
p->state = TASK_NEW;
|
|
|
|
/*
|
|
* Make sure we do not leak PI boosting priority to the child.
|
|
*/
|
|
p->prio = current->normal_prio;
|
|
|
|
uclamp_fork(p);
|
|
|
|
/*
|
|
* Revert to default priority/policy on fork if requested.
|
|
*/
|
|
if (unlikely(p->sched_reset_on_fork)) {
|
|
if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
|
|
p->policy = SCHED_NORMAL;
|
|
p->static_prio = NICE_TO_PRIO(0);
|
|
p->rt_priority = 0;
|
|
} else if (PRIO_TO_NICE(p->static_prio) < 0)
|
|
p->static_prio = NICE_TO_PRIO(0);
|
|
|
|
p->prio = p->normal_prio = __normal_prio(p);
|
|
set_load_weight(p, false);
|
|
|
|
/*
|
|
* We don't need the reset flag anymore after the fork. It has
|
|
* fulfilled its duty:
|
|
*/
|
|
p->sched_reset_on_fork = 0;
|
|
}
|
|
|
|
if (dl_prio(p->prio))
|
|
return -EAGAIN;
|
|
else if (rt_prio(p->prio))
|
|
p->sched_class = &rt_sched_class;
|
|
else
|
|
p->sched_class = &fair_sched_class;
|
|
|
|
init_entity_runnable_average(&p->se);
|
|
|
|
/*
|
|
* The child is not yet in the pid-hash so no cgroup attach races,
|
|
* and the cgroup is pinned to this child due to cgroup_fork()
|
|
* is ran before sched_fork().
|
|
*
|
|
* Silence PROVE_RCU.
|
|
*/
|
|
raw_spin_lock_irqsave(&p->pi_lock, flags);
|
|
rseq_migrate(p);
|
|
/*
|
|
* We're setting the CPU for the first time, we don't migrate,
|
|
* so use __set_task_cpu().
|
|
*/
|
|
__set_task_cpu(p, smp_processor_id());
|
|
if (p->sched_class->task_fork)
|
|
p->sched_class->task_fork(p);
|
|
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
|
|
#ifdef CONFIG_SCHED_INFO
|
|
if (likely(sched_info_on()))
|
|
memset(&p->sched_info, 0, sizeof(p->sched_info));
|
|
#endif
|
|
#if defined(CONFIG_SMP)
|
|
p->on_cpu = 0;
|
|
#endif
|
|
init_task_preempt_count(p);
|
|
#ifdef CONFIG_SMP
|
|
plist_node_init(&p->pushable_tasks, MAX_PRIO);
|
|
RB_CLEAR_NODE(&p->pushable_dl_tasks);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
void sched_post_fork(struct task_struct *p)
|
|
{
|
|
uclamp_post_fork(p);
|
|
}
|
|
|
|
unsigned long to_ratio(u64 period, u64 runtime)
|
|
{
|
|
if (runtime == RUNTIME_INF)
|
|
return BW_UNIT;
|
|
|
|
/*
|
|
* Doing this here saves a lot of checks in all
|
|
* the calling paths, and returning zero seems
|
|
* safe for them anyway.
|
|
*/
|
|
if (period == 0)
|
|
return 0;
|
|
|
|
return div64_u64(runtime << BW_SHIFT, period);
|
|
}
|
|
|
|
/*
|
|
* wake_up_new_task - wake up a newly created task for the first time.
|
|
*
|
|
* This function will do some initial scheduler statistics housekeeping
|
|
* that must be done for every newly created context, then puts the task
|
|
* on the runqueue and wakes it.
|
|
*/
|
|
void wake_up_new_task(struct task_struct *p)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
|
|
p->state = TASK_RUNNING;
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Fork balancing, do it here and not earlier because:
|
|
* - cpus_ptr can change in the fork path
|
|
* - any previously selected CPU might disappear through hotplug
|
|
*
|
|
* Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
|
|
* as we're not fully set-up yet.
|
|
*/
|
|
p->recent_used_cpu = task_cpu(p);
|
|
rseq_migrate(p);
|
|
__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
|
|
#endif
|
|
rq = __task_rq_lock(p, &rf);
|
|
update_rq_clock(rq);
|
|
post_init_entity_util_avg(p);
|
|
|
|
activate_task(rq, p, ENQUEUE_NOCLOCK);
|
|
trace_sched_wakeup_new(p);
|
|
check_preempt_curr(rq, p, WF_FORK);
|
|
#ifdef CONFIG_SMP
|
|
if (p->sched_class->task_woken) {
|
|
/*
|
|
* Nothing relies on rq->lock after this, so its fine to
|
|
* drop it.
|
|
*/
|
|
rq_unpin_lock(rq, &rf);
|
|
p->sched_class->task_woken(rq, p);
|
|
rq_repin_lock(rq, &rf);
|
|
}
|
|
#endif
|
|
task_rq_unlock(rq, p, &rf);
|
|
}
|
|
|
|
#ifdef CONFIG_PREEMPT_NOTIFIERS
|
|
|
|
static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
|
|
|
|
void preempt_notifier_inc(void)
|
|
{
|
|
static_branch_inc(&preempt_notifier_key);
|
|
}
|
|
EXPORT_SYMBOL_GPL(preempt_notifier_inc);
|
|
|
|
void preempt_notifier_dec(void)
|
|
{
|
|
static_branch_dec(&preempt_notifier_key);
|
|
}
|
|
EXPORT_SYMBOL_GPL(preempt_notifier_dec);
|
|
|
|
/**
|
|
* preempt_notifier_register - tell me when current is being preempted & rescheduled
|
|
* @notifier: notifier struct to register
|
|
*/
|
|
void preempt_notifier_register(struct preempt_notifier *notifier)
|
|
{
|
|
if (!static_branch_unlikely(&preempt_notifier_key))
|
|
WARN(1, "registering preempt_notifier while notifiers disabled\n");
|
|
|
|
hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
|
|
}
|
|
EXPORT_SYMBOL_GPL(preempt_notifier_register);
|
|
|
|
/**
|
|
* preempt_notifier_unregister - no longer interested in preemption notifications
|
|
* @notifier: notifier struct to unregister
|
|
*
|
|
* This is *not* safe to call from within a preemption notifier.
|
|
*/
|
|
void preempt_notifier_unregister(struct preempt_notifier *notifier)
|
|
{
|
|
hlist_del(¬ifier->link);
|
|
}
|
|
EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
|
|
|
|
static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
|
|
{
|
|
struct preempt_notifier *notifier;
|
|
|
|
hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
|
|
notifier->ops->sched_in(notifier, raw_smp_processor_id());
|
|
}
|
|
|
|
static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
|
|
{
|
|
if (static_branch_unlikely(&preempt_notifier_key))
|
|
__fire_sched_in_preempt_notifiers(curr);
|
|
}
|
|
|
|
static void
|
|
__fire_sched_out_preempt_notifiers(struct task_struct *curr,
|
|
struct task_struct *next)
|
|
{
|
|
struct preempt_notifier *notifier;
|
|
|
|
hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
|
|
notifier->ops->sched_out(notifier, next);
|
|
}
|
|
|
|
static __always_inline void
|
|
fire_sched_out_preempt_notifiers(struct task_struct *curr,
|
|
struct task_struct *next)
|
|
{
|
|
if (static_branch_unlikely(&preempt_notifier_key))
|
|
__fire_sched_out_preempt_notifiers(curr, next);
|
|
}
|
|
|
|
#else /* !CONFIG_PREEMPT_NOTIFIERS */
|
|
|
|
static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
|
|
{
|
|
}
|
|
|
|
static inline void
|
|
fire_sched_out_preempt_notifiers(struct task_struct *curr,
|
|
struct task_struct *next)
|
|
{
|
|
}
|
|
|
|
#endif /* CONFIG_PREEMPT_NOTIFIERS */
|
|
|
|
static inline void prepare_task(struct task_struct *next)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Claim the task as running, we do this before switching to it
|
|
* such that any running task will have this set.
|
|
*
|
|
* See the ttwu() WF_ON_CPU case and its ordering comment.
|
|
*/
|
|
WRITE_ONCE(next->on_cpu, 1);
|
|
#endif
|
|
}
|
|
|
|
static inline void finish_task(struct task_struct *prev)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* This must be the very last reference to @prev from this CPU. After
|
|
* p->on_cpu is cleared, the task can be moved to a different CPU. We
|
|
* must ensure this doesn't happen until the switch is completely
|
|
* finished.
|
|
*
|
|
* In particular, the load of prev->state in finish_task_switch() must
|
|
* happen before this.
|
|
*
|
|
* Pairs with the smp_cond_load_acquire() in try_to_wake_up().
|
|
*/
|
|
smp_store_release(&prev->on_cpu, 0);
|
|
#endif
|
|
}
|
|
|
|
static inline void
|
|
prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
|
|
{
|
|
/*
|
|
* Since the runqueue lock will be released by the next
|
|
* task (which is an invalid locking op but in the case
|
|
* of the scheduler it's an obvious special-case), so we
|
|
* do an early lockdep release here:
|
|
*/
|
|
rq_unpin_lock(rq, rf);
|
|
spin_release(&rq->lock.dep_map, _THIS_IP_);
|
|
#ifdef CONFIG_DEBUG_SPINLOCK
|
|
/* this is a valid case when another task releases the spinlock */
|
|
rq->lock.owner = next;
|
|
#endif
|
|
}
|
|
|
|
static inline void finish_lock_switch(struct rq *rq)
|
|
{
|
|
/*
|
|
* If we are tracking spinlock dependencies then we have to
|
|
* fix up the runqueue lock - which gets 'carried over' from
|
|
* prev into current:
|
|
*/
|
|
spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
|
|
raw_spin_unlock_irq(&rq->lock);
|
|
}
|
|
|
|
/*
|
|
* NOP if the arch has not defined these:
|
|
*/
|
|
|
|
#ifndef prepare_arch_switch
|
|
# define prepare_arch_switch(next) do { } while (0)
|
|
#endif
|
|
|
|
#ifndef finish_arch_post_lock_switch
|
|
# define finish_arch_post_lock_switch() do { } while (0)
|
|
#endif
|
|
|
|
/**
|
|
* prepare_task_switch - prepare to switch tasks
|
|
* @rq: the runqueue preparing to switch
|
|
* @prev: the current task that is being switched out
|
|
* @next: the task we are going to switch to.
|
|
*
|
|
* This is called with the rq lock held and interrupts off. It must
|
|
* be paired with a subsequent finish_task_switch after the context
|
|
* switch.
|
|
*
|
|
* prepare_task_switch sets up locking and calls architecture specific
|
|
* hooks.
|
|
*/
|
|
static inline void
|
|
prepare_task_switch(struct rq *rq, struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
kcov_prepare_switch(prev);
|
|
sched_info_switch(rq, prev, next);
|
|
perf_event_task_sched_out(prev, next);
|
|
rseq_preempt(prev);
|
|
fire_sched_out_preempt_notifiers(prev, next);
|
|
prepare_task(next);
|
|
prepare_arch_switch(next);
|
|
}
|
|
|
|
/**
|
|
* finish_task_switch - clean up after a task-switch
|
|
* @prev: the thread we just switched away from.
|
|
*
|
|
* finish_task_switch must be called after the context switch, paired
|
|
* with a prepare_task_switch call before the context switch.
|
|
* finish_task_switch will reconcile locking set up by prepare_task_switch,
|
|
* and do any other architecture-specific cleanup actions.
|
|
*
|
|
* Note that we may have delayed dropping an mm in context_switch(). If
|
|
* so, we finish that here outside of the runqueue lock. (Doing it
|
|
* with the lock held can cause deadlocks; see schedule() for
|
|
* details.)
|
|
*
|
|
* The context switch have flipped the stack from under us and restored the
|
|
* local variables which were saved when this task called schedule() in the
|
|
* past. prev == current is still correct but we need to recalculate this_rq
|
|
* because prev may have moved to another CPU.
|
|
*/
|
|
static struct rq *finish_task_switch(struct task_struct *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
struct rq *rq = this_rq();
|
|
struct mm_struct *mm = rq->prev_mm;
|
|
long prev_state;
|
|
|
|
/*
|
|
* The previous task will have left us with a preempt_count of 2
|
|
* because it left us after:
|
|
*
|
|
* schedule()
|
|
* preempt_disable(); // 1
|
|
* __schedule()
|
|
* raw_spin_lock_irq(&rq->lock) // 2
|
|
*
|
|
* Also, see FORK_PREEMPT_COUNT.
|
|
*/
|
|
if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
|
|
"corrupted preempt_count: %s/%d/0x%x\n",
|
|
current->comm, current->pid, preempt_count()))
|
|
preempt_count_set(FORK_PREEMPT_COUNT);
|
|
|
|
rq->prev_mm = NULL;
|
|
|
|
/*
|
|
* A task struct has one reference for the use as "current".
|
|
* If a task dies, then it sets TASK_DEAD in tsk->state and calls
|
|
* schedule one last time. The schedule call will never return, and
|
|
* the scheduled task must drop that reference.
|
|
*
|
|
* We must observe prev->state before clearing prev->on_cpu (in
|
|
* finish_task), otherwise a concurrent wakeup can get prev
|
|
* running on another CPU and we could rave with its RUNNING -> DEAD
|
|
* transition, resulting in a double drop.
|
|
*/
|
|
prev_state = prev->state;
|
|
vtime_task_switch(prev);
|
|
perf_event_task_sched_in(prev, current);
|
|
finish_task(prev);
|
|
finish_lock_switch(rq);
|
|
finish_arch_post_lock_switch();
|
|
kcov_finish_switch(current);
|
|
|
|
fire_sched_in_preempt_notifiers(current);
|
|
/*
|
|
* When switching through a kernel thread, the loop in
|
|
* membarrier_{private,global}_expedited() may have observed that
|
|
* kernel thread and not issued an IPI. It is therefore possible to
|
|
* schedule between user->kernel->user threads without passing though
|
|
* switch_mm(). Membarrier requires a barrier after storing to
|
|
* rq->curr, before returning to userspace, so provide them here:
|
|
*
|
|
* - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
|
|
* provided by mmdrop(),
|
|
* - a sync_core for SYNC_CORE.
|
|
*/
|
|
if (mm) {
|
|
membarrier_mm_sync_core_before_usermode(mm);
|
|
mmdrop(mm);
|
|
}
|
|
if (unlikely(prev_state == TASK_DEAD)) {
|
|
if (prev->sched_class->task_dead)
|
|
prev->sched_class->task_dead(prev);
|
|
|
|
/*
|
|
* Remove function-return probe instances associated with this
|
|
* task and put them back on the free list.
|
|
*/
|
|
kprobe_flush_task(prev);
|
|
|
|
/* Task is done with its stack. */
|
|
put_task_stack(prev);
|
|
|
|
put_task_struct_rcu_user(prev);
|
|
}
|
|
|
|
tick_nohz_task_switch();
|
|
return rq;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/* rq->lock is NOT held, but preemption is disabled */
|
|
static void __balance_callback(struct rq *rq)
|
|
{
|
|
struct callback_head *head, *next;
|
|
void (*func)(struct rq *rq);
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
head = rq->balance_callback;
|
|
rq->balance_callback = NULL;
|
|
while (head) {
|
|
func = (void (*)(struct rq *))head->func;
|
|
next = head->next;
|
|
head->next = NULL;
|
|
head = next;
|
|
|
|
func(rq);
|
|
}
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
static inline void balance_callback(struct rq *rq)
|
|
{
|
|
if (unlikely(rq->balance_callback))
|
|
__balance_callback(rq);
|
|
}
|
|
|
|
#else
|
|
|
|
static inline void balance_callback(struct rq *rq)
|
|
{
|
|
}
|
|
|
|
#endif
|
|
|
|
/**
|
|
* schedule_tail - first thing a freshly forked thread must call.
|
|
* @prev: the thread we just switched away from.
|
|
*/
|
|
asmlinkage __visible void schedule_tail(struct task_struct *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
struct rq *rq;
|
|
|
|
/*
|
|
* New tasks start with FORK_PREEMPT_COUNT, see there and
|
|
* finish_task_switch() for details.
|
|
*
|
|
* finish_task_switch() will drop rq->lock() and lower preempt_count
|
|
* and the preempt_enable() will end up enabling preemption (on
|
|
* PREEMPT_COUNT kernels).
|
|
*/
|
|
|
|
rq = finish_task_switch(prev);
|
|
balance_callback(rq);
|
|
preempt_enable();
|
|
|
|
if (current->set_child_tid)
|
|
put_user(task_pid_vnr(current), current->set_child_tid);
|
|
|
|
calculate_sigpending();
|
|
}
|
|
|
|
/*
|
|
* context_switch - switch to the new MM and the new thread's register state.
|
|
*/
|
|
static __always_inline struct rq *
|
|
context_switch(struct rq *rq, struct task_struct *prev,
|
|
struct task_struct *next, struct rq_flags *rf)
|
|
{
|
|
prepare_task_switch(rq, prev, next);
|
|
|
|
/*
|
|
* For paravirt, this is coupled with an exit in switch_to to
|
|
* combine the page table reload and the switch backend into
|
|
* one hypercall.
|
|
*/
|
|
arch_start_context_switch(prev);
|
|
|
|
/*
|
|
* kernel -> kernel lazy + transfer active
|
|
* user -> kernel lazy + mmgrab() active
|
|
*
|
|
* kernel -> user switch + mmdrop() active
|
|
* user -> user switch
|
|
*/
|
|
if (!next->mm) { // to kernel
|
|
enter_lazy_tlb(prev->active_mm, next);
|
|
|
|
next->active_mm = prev->active_mm;
|
|
if (prev->mm) // from user
|
|
mmgrab(prev->active_mm);
|
|
else
|
|
prev->active_mm = NULL;
|
|
} else { // to user
|
|
membarrier_switch_mm(rq, prev->active_mm, next->mm);
|
|
/*
|
|
* sys_membarrier() requires an smp_mb() between setting
|
|
* rq->curr / membarrier_switch_mm() and returning to userspace.
|
|
*
|
|
* The below provides this either through switch_mm(), or in
|
|
* case 'prev->active_mm == next->mm' through
|
|
* finish_task_switch()'s mmdrop().
|
|
*/
|
|
switch_mm_irqs_off(prev->active_mm, next->mm, next);
|
|
|
|
if (!prev->mm) { // from kernel
|
|
/* will mmdrop() in finish_task_switch(). */
|
|
rq->prev_mm = prev->active_mm;
|
|
prev->active_mm = NULL;
|
|
}
|
|
}
|
|
|
|
rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
|
|
|
|
prepare_lock_switch(rq, next, rf);
|
|
|
|
/* Here we just switch the register state and the stack. */
|
|
switch_to(prev, next, prev);
|
|
barrier();
|
|
|
|
return finish_task_switch(prev);
|
|
}
|
|
|
|
/*
|
|
* nr_running and nr_context_switches:
|
|
*
|
|
* externally visible scheduler statistics: current number of runnable
|
|
* threads, total number of context switches performed since bootup.
|
|
*/
|
|
unsigned long nr_running(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_online_cpu(i)
|
|
sum += cpu_rq(i)->nr_running;
|
|
|
|
return sum;
|
|
}
|
|
|
|
/*
|
|
* Check if only the current task is running on the CPU.
|
|
*
|
|
* Caution: this function does not check that the caller has disabled
|
|
* preemption, thus the result might have a time-of-check-to-time-of-use
|
|
* race. The caller is responsible to use it correctly, for example:
|
|
*
|
|
* - from a non-preemptible section (of course)
|
|
*
|
|
* - from a thread that is bound to a single CPU
|
|
*
|
|
* - in a loop with very short iterations (e.g. a polling loop)
|
|
*/
|
|
bool single_task_running(void)
|
|
{
|
|
return raw_rq()->nr_running == 1;
|
|
}
|
|
EXPORT_SYMBOL(single_task_running);
|
|
|
|
unsigned long long nr_context_switches(void)
|
|
{
|
|
int i;
|
|
unsigned long long sum = 0;
|
|
|
|
for_each_possible_cpu(i)
|
|
sum += cpu_rq(i)->nr_switches;
|
|
|
|
return sum;
|
|
}
|
|
|
|
/*
|
|
* Consumers of these two interfaces, like for example the cpuidle menu
|
|
* governor, are using nonsensical data. Preferring shallow idle state selection
|
|
* for a CPU that has IO-wait which might not even end up running the task when
|
|
* it does become runnable.
|
|
*/
|
|
|
|
unsigned long nr_iowait_cpu(int cpu)
|
|
{
|
|
return atomic_read(&cpu_rq(cpu)->nr_iowait);
|
|
}
|
|
|
|
/*
|
|
* IO-wait accounting, and how its mostly bollocks (on SMP).
|
|
*
|
|
* The idea behind IO-wait account is to account the idle time that we could
|
|
* have spend running if it were not for IO. That is, if we were to improve the
|
|
* storage performance, we'd have a proportional reduction in IO-wait time.
|
|
*
|
|
* This all works nicely on UP, where, when a task blocks on IO, we account
|
|
* idle time as IO-wait, because if the storage were faster, it could've been
|
|
* running and we'd not be idle.
|
|
*
|
|
* This has been extended to SMP, by doing the same for each CPU. This however
|
|
* is broken.
|
|
*
|
|
* Imagine for instance the case where two tasks block on one CPU, only the one
|
|
* CPU will have IO-wait accounted, while the other has regular idle. Even
|
|
* though, if the storage were faster, both could've ran at the same time,
|
|
* utilising both CPUs.
|
|
*
|
|
* This means, that when looking globally, the current IO-wait accounting on
|
|
* SMP is a lower bound, by reason of under accounting.
|
|
*
|
|
* Worse, since the numbers are provided per CPU, they are sometimes
|
|
* interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
|
|
* associated with any one particular CPU, it can wake to another CPU than it
|
|
* blocked on. This means the per CPU IO-wait number is meaningless.
|
|
*
|
|
* Task CPU affinities can make all that even more 'interesting'.
|
|
*/
|
|
|
|
unsigned long nr_iowait(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_possible_cpu(i)
|
|
sum += nr_iowait_cpu(i);
|
|
|
|
return sum;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/*
|
|
* sched_exec - execve() is a valuable balancing opportunity, because at
|
|
* this point the task has the smallest effective memory and cache footprint.
|
|
*/
|
|
void sched_exec(void)
|
|
{
|
|
struct task_struct *p = current;
|
|
unsigned long flags;
|
|
int dest_cpu;
|
|
|
|
raw_spin_lock_irqsave(&p->pi_lock, flags);
|
|
dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
|
|
if (dest_cpu == smp_processor_id())
|
|
goto unlock;
|
|
|
|
if (likely(cpu_active(dest_cpu))) {
|
|
struct migration_arg arg = { p, dest_cpu };
|
|
|
|
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
|
|
return;
|
|
}
|
|
unlock:
|
|
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
}
|
|
|
|
#endif
|
|
|
|
DEFINE_PER_CPU(struct kernel_stat, kstat);
|
|
DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
|
|
|
|
EXPORT_PER_CPU_SYMBOL(kstat);
|
|
EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
|
|
|
|
/*
|
|
* The function fair_sched_class.update_curr accesses the struct curr
|
|
* and its field curr->exec_start; when called from task_sched_runtime(),
|
|
* we observe a high rate of cache misses in practice.
|
|
* Prefetching this data results in improved performance.
|
|
*/
|
|
static inline void prefetch_curr_exec_start(struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
struct sched_entity *curr = (&p->se)->cfs_rq->curr;
|
|
#else
|
|
struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
|
|
#endif
|
|
prefetch(curr);
|
|
prefetch(&curr->exec_start);
|
|
}
|
|
|
|
/*
|
|
* Return accounted runtime for the task.
|
|
* In case the task is currently running, return the runtime plus current's
|
|
* pending runtime that have not been accounted yet.
|
|
*/
|
|
unsigned long long task_sched_runtime(struct task_struct *p)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
u64 ns;
|
|
|
|
#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
|
|
/*
|
|
* 64-bit doesn't need locks to atomically read a 64-bit value.
|
|
* So we have a optimization chance when the task's delta_exec is 0.
|
|
* Reading ->on_cpu is racy, but this is ok.
|
|
*
|
|
* If we race with it leaving CPU, we'll take a lock. So we're correct.
|
|
* If we race with it entering CPU, unaccounted time is 0. This is
|
|
* indistinguishable from the read occurring a few cycles earlier.
|
|
* If we see ->on_cpu without ->on_rq, the task is leaving, and has
|
|
* been accounted, so we're correct here as well.
|
|
*/
|
|
if (!p->on_cpu || !task_on_rq_queued(p))
|
|
return p->se.sum_exec_runtime;
|
|
#endif
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
/*
|
|
* Must be ->curr _and_ ->on_rq. If dequeued, we would
|
|
* project cycles that may never be accounted to this
|
|
* thread, breaking clock_gettime().
|
|
*/
|
|
if (task_current(rq, p) && task_on_rq_queued(p)) {
|
|
prefetch_curr_exec_start(p);
|
|
update_rq_clock(rq);
|
|
p->sched_class->update_curr(rq);
|
|
}
|
|
ns = p->se.sum_exec_runtime;
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* This function gets called by the timer code, with HZ frequency.
|
|
* We call it with interrupts disabled.
|
|
*/
|
|
void scheduler_tick(void)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct task_struct *curr = rq->curr;
|
|
struct rq_flags rf;
|
|
unsigned long thermal_pressure;
|
|
|
|
arch_scale_freq_tick();
|
|
sched_clock_tick();
|
|
|
|
rq_lock(rq, &rf);
|
|
|
|
update_rq_clock(rq);
|
|
thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
|
|
update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure);
|
|
curr->sched_class->task_tick(rq, curr, 0);
|
|
calc_global_load_tick(rq);
|
|
psi_task_tick(rq);
|
|
|
|
rq_unlock(rq, &rf);
|
|
|
|
perf_event_task_tick();
|
|
|
|
#ifdef CONFIG_SMP
|
|
rq->idle_balance = idle_cpu(cpu);
|
|
trigger_load_balance(rq);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_FULL
|
|
|
|
struct tick_work {
|
|
int cpu;
|
|
atomic_t state;
|
|
struct delayed_work work;
|
|
};
|
|
/* Values for ->state, see diagram below. */
|
|
#define TICK_SCHED_REMOTE_OFFLINE 0
|
|
#define TICK_SCHED_REMOTE_OFFLINING 1
|
|
#define TICK_SCHED_REMOTE_RUNNING 2
|
|
|
|
/*
|
|
* State diagram for ->state:
|
|
*
|
|
*
|
|
* TICK_SCHED_REMOTE_OFFLINE
|
|
* | ^
|
|
* | |
|
|
* | | sched_tick_remote()
|
|
* | |
|
|
* | |
|
|
* +--TICK_SCHED_REMOTE_OFFLINING
|
|
* | ^
|
|
* | |
|
|
* sched_tick_start() | | sched_tick_stop()
|
|
* | |
|
|
* V |
|
|
* TICK_SCHED_REMOTE_RUNNING
|
|
*
|
|
*
|
|
* Other transitions get WARN_ON_ONCE(), except that sched_tick_remote()
|
|
* and sched_tick_start() are happy to leave the state in RUNNING.
|
|
*/
|
|
|
|
static struct tick_work __percpu *tick_work_cpu;
|
|
|
|
static void sched_tick_remote(struct work_struct *work)
|
|
{
|
|
struct delayed_work *dwork = to_delayed_work(work);
|
|
struct tick_work *twork = container_of(dwork, struct tick_work, work);
|
|
int cpu = twork->cpu;
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct task_struct *curr;
|
|
struct rq_flags rf;
|
|
u64 delta;
|
|
int os;
|
|
|
|
/*
|
|
* Handle the tick only if it appears the remote CPU is running in full
|
|
* dynticks mode. The check is racy by nature, but missing a tick or
|
|
* having one too much is no big deal because the scheduler tick updates
|
|
* statistics and checks timeslices in a time-independent way, regardless
|
|
* of when exactly it is running.
|
|
*/
|
|
if (!tick_nohz_tick_stopped_cpu(cpu))
|
|
goto out_requeue;
|
|
|
|
rq_lock_irq(rq, &rf);
|
|
curr = rq->curr;
|
|
if (cpu_is_offline(cpu))
|
|
goto out_unlock;
|
|
|
|
update_rq_clock(rq);
|
|
|
|
if (!is_idle_task(curr)) {
|
|
/*
|
|
* Make sure the next tick runs within a reasonable
|
|
* amount of time.
|
|
*/
|
|
delta = rq_clock_task(rq) - curr->se.exec_start;
|
|
WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
|
|
}
|
|
curr->sched_class->task_tick(rq, curr, 0);
|
|
|
|
calc_load_nohz_remote(rq);
|
|
out_unlock:
|
|
rq_unlock_irq(rq, &rf);
|
|
out_requeue:
|
|
|
|
/*
|
|
* Run the remote tick once per second (1Hz). This arbitrary
|
|
* frequency is large enough to avoid overload but short enough
|
|
* to keep scheduler internal stats reasonably up to date. But
|
|
* first update state to reflect hotplug activity if required.
|
|
*/
|
|
os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);
|
|
WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);
|
|
if (os == TICK_SCHED_REMOTE_RUNNING)
|
|
queue_delayed_work(system_unbound_wq, dwork, HZ);
|
|
}
|
|
|
|
static void sched_tick_start(int cpu)
|
|
{
|
|
int os;
|
|
struct tick_work *twork;
|
|
|
|
if (housekeeping_cpu(cpu, HK_FLAG_TICK))
|
|
return;
|
|
|
|
WARN_ON_ONCE(!tick_work_cpu);
|
|
|
|
twork = per_cpu_ptr(tick_work_cpu, cpu);
|
|
os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING);
|
|
WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING);
|
|
if (os == TICK_SCHED_REMOTE_OFFLINE) {
|
|
twork->cpu = cpu;
|
|
INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
|
|
queue_delayed_work(system_unbound_wq, &twork->work, HZ);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static void sched_tick_stop(int cpu)
|
|
{
|
|
struct tick_work *twork;
|
|
int os;
|
|
|
|
if (housekeeping_cpu(cpu, HK_FLAG_TICK))
|
|
return;
|
|
|
|
WARN_ON_ONCE(!tick_work_cpu);
|
|
|
|
twork = per_cpu_ptr(tick_work_cpu, cpu);
|
|
/* There cannot be competing actions, but don't rely on stop-machine. */
|
|
os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING);
|
|
WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING);
|
|
/* Don't cancel, as this would mess up the state machine. */
|
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
int __init sched_tick_offload_init(void)
|
|
{
|
|
tick_work_cpu = alloc_percpu(struct tick_work);
|
|
BUG_ON(!tick_work_cpu);
|
|
return 0;
|
|
}
|
|
|
|
#else /* !CONFIG_NO_HZ_FULL */
|
|
static inline void sched_tick_start(int cpu) { }
|
|
static inline void sched_tick_stop(int cpu) { }
|
|
#endif
|
|
|
|
#if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \
|
|
defined(CONFIG_TRACE_PREEMPT_TOGGLE))
|
|
/*
|
|
* If the value passed in is equal to the current preempt count
|
|
* then we just disabled preemption. Start timing the latency.
|
|
*/
|
|
static inline void preempt_latency_start(int val)
|
|
{
|
|
if (preempt_count() == val) {
|
|
unsigned long ip = get_lock_parent_ip();
|
|
#ifdef CONFIG_DEBUG_PREEMPT
|
|
current->preempt_disable_ip = ip;
|
|
#endif
|
|
trace_preempt_off(CALLER_ADDR0, ip);
|
|
}
|
|
}
|
|
|
|
void preempt_count_add(int val)
|
|
{
|
|
#ifdef CONFIG_DEBUG_PREEMPT
|
|
/*
|
|
* Underflow?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
|
|
return;
|
|
#endif
|
|
__preempt_count_add(val);
|
|
#ifdef CONFIG_DEBUG_PREEMPT
|
|
/*
|
|
* Spinlock count overflowing soon?
|
|
*/
|
|
DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
|
|
PREEMPT_MASK - 10);
|
|
#endif
|
|
preempt_latency_start(val);
|
|
}
|
|
EXPORT_SYMBOL(preempt_count_add);
|
|
NOKPROBE_SYMBOL(preempt_count_add);
|
|
|
|
/*
|
|
* If the value passed in equals to the current preempt count
|
|
* then we just enabled preemption. Stop timing the latency.
|
|
*/
|
|
static inline void preempt_latency_stop(int val)
|
|
{
|
|
if (preempt_count() == val)
|
|
trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
|
|
}
|
|
|
|
void preempt_count_sub(int val)
|
|
{
|
|
#ifdef CONFIG_DEBUG_PREEMPT
|
|
/*
|
|
* Underflow?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
|
|
return;
|
|
/*
|
|
* Is the spinlock portion underflowing?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
|
|
!(preempt_count() & PREEMPT_MASK)))
|
|
return;
|
|
#endif
|
|
|
|
preempt_latency_stop(val);
|
|
__preempt_count_sub(val);
|
|
}
|
|
EXPORT_SYMBOL(preempt_count_sub);
|
|
NOKPROBE_SYMBOL(preempt_count_sub);
|
|
|
|
#else
|
|
static inline void preempt_latency_start(int val) { }
|
|
static inline void preempt_latency_stop(int val) { }
|
|
#endif
|
|
|
|
static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_DEBUG_PREEMPT
|
|
return p->preempt_disable_ip;
|
|
#else
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Print scheduling while atomic bug:
|
|
*/
|
|
static noinline void __schedule_bug(struct task_struct *prev)
|
|
{
|
|
/* Save this before calling printk(), since that will clobber it */
|
|
unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
|
|
|
|
if (oops_in_progress)
|
|
return;
|
|
|
|
printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
|
|
prev->comm, prev->pid, preempt_count());
|
|
|
|
debug_show_held_locks(prev);
|
|
print_modules();
|
|
if (irqs_disabled())
|
|
print_irqtrace_events(prev);
|
|
if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
|
|
&& in_atomic_preempt_off()) {
|
|
pr_err("Preemption disabled at:");
|
|
print_ip_sym(KERN_ERR, preempt_disable_ip);
|
|
}
|
|
if (panic_on_warn)
|
|
panic("scheduling while atomic\n");
|
|
|
|
dump_stack();
|
|
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
|
|
}
|
|
|
|
/*
|
|
* Various schedule()-time debugging checks and statistics:
|
|
*/
|
|
static inline void schedule_debug(struct task_struct *prev, bool preempt)
|
|
{
|
|
#ifdef CONFIG_SCHED_STACK_END_CHECK
|
|
if (task_stack_end_corrupted(prev))
|
|
panic("corrupted stack end detected inside scheduler\n");
|
|
|
|
if (task_scs_end_corrupted(prev))
|
|
panic("corrupted shadow stack detected inside scheduler\n");
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
|
|
if (!preempt && prev->state && prev->non_block_count) {
|
|
printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n",
|
|
prev->comm, prev->pid, prev->non_block_count);
|
|
dump_stack();
|
|
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
|
|
}
|
|
#endif
|
|
|
|
if (unlikely(in_atomic_preempt_off())) {
|
|
__schedule_bug(prev);
|
|
preempt_count_set(PREEMPT_DISABLED);
|
|
}
|
|
rcu_sleep_check();
|
|
|
|
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
|
|
|
|
schedstat_inc(this_rq()->sched_count);
|
|
}
|
|
|
|
static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
|
|
struct rq_flags *rf)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
const struct sched_class *class;
|
|
/*
|
|
* We must do the balancing pass before put_prev_task(), such
|
|
* that when we release the rq->lock the task is in the same
|
|
* state as before we took rq->lock.
|
|
*
|
|
* We can terminate the balance pass as soon as we know there is
|
|
* a runnable task of @class priority or higher.
|
|
*/
|
|
for_class_range(class, prev->sched_class, &idle_sched_class) {
|
|
if (class->balance(rq, prev, rf))
|
|
break;
|
|
}
|
|
#endif
|
|
|
|
put_prev_task(rq, prev);
|
|
}
|
|
|
|
/*
|
|
* Pick up the highest-prio task:
|
|
*/
|
|
static inline struct task_struct *
|
|
pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
|
|
{
|
|
const struct sched_class *class;
|
|
struct task_struct *p;
|
|
|
|
/*
|
|
* Optimization: we know that if all tasks are in the fair class we can
|
|
* call that function directly, but only if the @prev task wasn't of a
|
|
* higher scheduling class, because otherwise those loose the
|
|
* opportunity to pull in more work from other CPUs.
|
|
*/
|
|
if (likely(prev->sched_class <= &fair_sched_class &&
|
|
rq->nr_running == rq->cfs.h_nr_running)) {
|
|
|
|
p = pick_next_task_fair(rq, prev, rf);
|
|
if (unlikely(p == RETRY_TASK))
|
|
goto restart;
|
|
|
|
/* Assumes fair_sched_class->next == idle_sched_class */
|
|
if (!p) {
|
|
put_prev_task(rq, prev);
|
|
p = pick_next_task_idle(rq);
|
|
}
|
|
|
|
return p;
|
|
}
|
|
|
|
restart:
|
|
put_prev_task_balance(rq, prev, rf);
|
|
|
|
for_each_class(class) {
|
|
p = class->pick_next_task(rq);
|
|
if (p)
|
|
return p;
|
|
}
|
|
|
|
/* The idle class should always have a runnable task: */
|
|
BUG();
|
|
}
|
|
|
|
/*
|
|
* __schedule() is the main scheduler function.
|
|
*
|
|
* The main means of driving the scheduler and thus entering this function are:
|
|
*
|
|
* 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
|
|
*
|
|
* 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
|
|
* paths. For example, see arch/x86/entry_64.S.
|
|
*
|
|
* To drive preemption between tasks, the scheduler sets the flag in timer
|
|
* interrupt handler scheduler_tick().
|
|
*
|
|
* 3. Wakeups don't really cause entry into schedule(). They add a
|
|
* task to the run-queue and that's it.
|
|
*
|
|
* Now, if the new task added to the run-queue preempts the current
|
|
* task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
|
|
* called on the nearest possible occasion:
|
|
*
|
|
* - If the kernel is preemptible (CONFIG_PREEMPTION=y):
|
|
*
|
|
* - in syscall or exception context, at the next outmost
|
|
* preempt_enable(). (this might be as soon as the wake_up()'s
|
|
* spin_unlock()!)
|
|
*
|
|
* - in IRQ context, return from interrupt-handler to
|
|
* preemptible context
|
|
*
|
|
* - If the kernel is not preemptible (CONFIG_PREEMPTION is not set)
|
|
* then at the next:
|
|
*
|
|
* - cond_resched() call
|
|
* - explicit schedule() call
|
|
* - return from syscall or exception to user-space
|
|
* - return from interrupt-handler to user-space
|
|
*
|
|
* WARNING: must be called with preemption disabled!
|
|
*/
|
|
static void __sched notrace __schedule(bool preempt)
|
|
{
|
|
struct task_struct *prev, *next;
|
|
unsigned long *switch_count;
|
|
unsigned long prev_state;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
int cpu;
|
|
|
|
cpu = smp_processor_id();
|
|
rq = cpu_rq(cpu);
|
|
prev = rq->curr;
|
|
|
|
schedule_debug(prev, preempt);
|
|
|
|
if (sched_feat(HRTICK))
|
|
hrtick_clear(rq);
|
|
|
|
local_irq_disable();
|
|
rcu_note_context_switch(preempt);
|
|
|
|
/*
|
|
* Make sure that signal_pending_state()->signal_pending() below
|
|
* can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
|
|
* done by the caller to avoid the race with signal_wake_up():
|
|
*
|
|
* __set_current_state(@state) signal_wake_up()
|
|
* schedule() set_tsk_thread_flag(p, TIF_SIGPENDING)
|
|
* wake_up_state(p, state)
|
|
* LOCK rq->lock LOCK p->pi_state
|
|
* smp_mb__after_spinlock() smp_mb__after_spinlock()
|
|
* if (signal_pending_state()) if (p->state & @state)
|
|
*
|
|
* Also, the membarrier system call requires a full memory barrier
|
|
* after coming from user-space, before storing to rq->curr.
|
|
*/
|
|
rq_lock(rq, &rf);
|
|
smp_mb__after_spinlock();
|
|
|
|
/* Promote REQ to ACT */
|
|
rq->clock_update_flags <<= 1;
|
|
update_rq_clock(rq);
|
|
|
|
switch_count = &prev->nivcsw;
|
|
|
|
/*
|
|
* We must load prev->state once (task_struct::state is volatile), such
|
|
* that:
|
|
*
|
|
* - we form a control dependency vs deactivate_task() below.
|
|
* - ptrace_{,un}freeze_traced() can change ->state underneath us.
|
|
*/
|
|
prev_state = prev->state;
|
|
if (!preempt && prev_state) {
|
|
if (signal_pending_state(prev_state, prev)) {
|
|
prev->state = TASK_RUNNING;
|
|
} else {
|
|
prev->sched_contributes_to_load =
|
|
(prev_state & TASK_UNINTERRUPTIBLE) &&
|
|
!(prev_state & TASK_NOLOAD) &&
|
|
!(prev->flags & PF_FROZEN);
|
|
|
|
if (prev->sched_contributes_to_load)
|
|
rq->nr_uninterruptible++;
|
|
|
|
/*
|
|
* __schedule() ttwu()
|
|
* prev_state = prev->state; if (p->on_rq && ...)
|
|
* if (prev_state) goto out;
|
|
* p->on_rq = 0; smp_acquire__after_ctrl_dep();
|
|
* p->state = TASK_WAKING
|
|
*
|
|
* Where __schedule() and ttwu() have matching control dependencies.
|
|
*
|
|
* After this, schedule() must not care about p->state any more.
|
|
*/
|
|
deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
|
|
|
|
if (prev->in_iowait) {
|
|
atomic_inc(&rq->nr_iowait);
|
|
delayacct_blkio_start();
|
|
}
|
|
}
|
|
switch_count = &prev->nvcsw;
|
|
}
|
|
|
|
next = pick_next_task(rq, prev, &rf);
|
|
clear_tsk_need_resched(prev);
|
|
clear_preempt_need_resched();
|
|
|
|
if (likely(prev != next)) {
|
|
rq->nr_switches++;
|
|
/*
|
|
* RCU users of rcu_dereference(rq->curr) may not see
|
|
* changes to task_struct made by pick_next_task().
|
|
*/
|
|
RCU_INIT_POINTER(rq->curr, next);
|
|
/*
|
|
* The membarrier system call requires each architecture
|
|
* to have a full memory barrier after updating
|
|
* rq->curr, before returning to user-space.
|
|
*
|
|
* Here are the schemes providing that barrier on the
|
|
* various architectures:
|
|
* - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
|
|
* switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
|
|
* - finish_lock_switch() for weakly-ordered
|
|
* architectures where spin_unlock is a full barrier,
|
|
* - switch_to() for arm64 (weakly-ordered, spin_unlock
|
|
* is a RELEASE barrier),
|
|
*/
|
|
++*switch_count;
|
|
|
|
psi_sched_switch(prev, next, !task_on_rq_queued(prev));
|
|
|
|
trace_sched_switch(preempt, prev, next);
|
|
|
|
/* Also unlocks the rq: */
|
|
rq = context_switch(rq, prev, next, &rf);
|
|
} else {
|
|
rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
|
|
rq_unlock_irq(rq, &rf);
|
|
}
|
|
|
|
balance_callback(rq);
|
|
}
|
|
|
|
void __noreturn do_task_dead(void)
|
|
{
|
|
/* Causes final put_task_struct in finish_task_switch(): */
|
|
set_special_state(TASK_DEAD);
|
|
|
|
/* Tell freezer to ignore us: */
|
|
current->flags |= PF_NOFREEZE;
|
|
|
|
__schedule(false);
|
|
BUG();
|
|
|
|
/* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
|
|
for (;;)
|
|
cpu_relax();
|
|
}
|
|
|
|
static inline void sched_submit_work(struct task_struct *tsk)
|
|
{
|
|
unsigned int task_flags;
|
|
|
|
if (!tsk->state)
|
|
return;
|
|
|
|
task_flags = tsk->flags;
|
|
/*
|
|
* If a worker went to sleep, notify and ask workqueue whether
|
|
* it wants to wake up a task to maintain concurrency.
|
|
* As this function is called inside the schedule() context,
|
|
* we disable preemption to avoid it calling schedule() again
|
|
* in the possible wakeup of a kworker and because wq_worker_sleeping()
|
|
* requires it.
|
|
*/
|
|
if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
|
|
preempt_disable();
|
|
if (task_flags & PF_WQ_WORKER)
|
|
wq_worker_sleeping(tsk);
|
|
else
|
|
io_wq_worker_sleeping(tsk);
|
|
preempt_enable_no_resched();
|
|
}
|
|
|
|
if (tsk_is_pi_blocked(tsk))
|
|
return;
|
|
|
|
/*
|
|
* If we are going to sleep and we have plugged IO queued,
|
|
* make sure to submit it to avoid deadlocks.
|
|
*/
|
|
if (blk_needs_flush_plug(tsk))
|
|
blk_schedule_flush_plug(tsk);
|
|
}
|
|
|
|
static void sched_update_worker(struct task_struct *tsk)
|
|
{
|
|
if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
|
|
if (tsk->flags & PF_WQ_WORKER)
|
|
wq_worker_running(tsk);
|
|
else
|
|
io_wq_worker_running(tsk);
|
|
}
|
|
}
|
|
|
|
asmlinkage __visible void __sched schedule(void)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
sched_submit_work(tsk);
|
|
do {
|
|
preempt_disable();
|
|
__schedule(false);
|
|
sched_preempt_enable_no_resched();
|
|
} while (need_resched());
|
|
sched_update_worker(tsk);
|
|
}
|
|
EXPORT_SYMBOL(schedule);
|
|
|
|
/*
|
|
* synchronize_rcu_tasks() makes sure that no task is stuck in preempted
|
|
* state (have scheduled out non-voluntarily) by making sure that all
|
|
* tasks have either left the run queue or have gone into user space.
|
|
* As idle tasks do not do either, they must not ever be preempted
|
|
* (schedule out non-voluntarily).
|
|
*
|
|
* schedule_idle() is similar to schedule_preempt_disable() except that it
|
|
* never enables preemption because it does not call sched_submit_work().
|
|
*/
|
|
void __sched schedule_idle(void)
|
|
{
|
|
/*
|
|
* As this skips calling sched_submit_work(), which the idle task does
|
|
* regardless because that function is a nop when the task is in a
|
|
* TASK_RUNNING state, make sure this isn't used someplace that the
|
|
* current task can be in any other state. Note, idle is always in the
|
|
* TASK_RUNNING state.
|
|
*/
|
|
WARN_ON_ONCE(current->state);
|
|
do {
|
|
__schedule(false);
|
|
} while (need_resched());
|
|
}
|
|
|
|
#ifdef CONFIG_CONTEXT_TRACKING
|
|
asmlinkage __visible void __sched schedule_user(void)
|
|
{
|
|
/*
|
|
* If we come here after a random call to set_need_resched(),
|
|
* or we have been woken up remotely but the IPI has not yet arrived,
|
|
* we haven't yet exited the RCU idle mode. Do it here manually until
|
|
* we find a better solution.
|
|
*
|
|
* NB: There are buggy callers of this function. Ideally we
|
|
* should warn if prev_state != CONTEXT_USER, but that will trigger
|
|
* too frequently to make sense yet.
|
|
*/
|
|
enum ctx_state prev_state = exception_enter();
|
|
schedule();
|
|
exception_exit(prev_state);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* schedule_preempt_disabled - called with preemption disabled
|
|
*
|
|
* Returns with preemption disabled. Note: preempt_count must be 1
|
|
*/
|
|
void __sched schedule_preempt_disabled(void)
|
|
{
|
|
sched_preempt_enable_no_resched();
|
|
schedule();
|
|
preempt_disable();
|
|
}
|
|
|
|
static void __sched notrace preempt_schedule_common(void)
|
|
{
|
|
do {
|
|
/*
|
|
* Because the function tracer can trace preempt_count_sub()
|
|
* and it also uses preempt_enable/disable_notrace(), if
|
|
* NEED_RESCHED is set, the preempt_enable_notrace() called
|
|
* by the function tracer will call this function again and
|
|
* cause infinite recursion.
|
|
*
|
|
* Preemption must be disabled here before the function
|
|
* tracer can trace. Break up preempt_disable() into two
|
|
* calls. One to disable preemption without fear of being
|
|
* traced. The other to still record the preemption latency,
|
|
* which can also be traced by the function tracer.
|
|
*/
|
|
preempt_disable_notrace();
|
|
preempt_latency_start(1);
|
|
__schedule(true);
|
|
preempt_latency_stop(1);
|
|
preempt_enable_no_resched_notrace();
|
|
|
|
/*
|
|
* Check again in case we missed a preemption opportunity
|
|
* between schedule and now.
|
|
*/
|
|
} while (need_resched());
|
|
}
|
|
|
|
#ifdef CONFIG_PREEMPTION
|
|
/*
|
|
* This is the entry point to schedule() from in-kernel preemption
|
|
* off of preempt_enable.
|
|
*/
|
|
asmlinkage __visible void __sched notrace preempt_schedule(void)
|
|
{
|
|
/*
|
|
* If there is a non-zero preempt_count or interrupts are disabled,
|
|
* we do not want to preempt the current task. Just return..
|
|
*/
|
|
if (likely(!preemptible()))
|
|
return;
|
|
|
|
preempt_schedule_common();
|
|
}
|
|
NOKPROBE_SYMBOL(preempt_schedule);
|
|
EXPORT_SYMBOL(preempt_schedule);
|
|
|
|
/**
|
|
* preempt_schedule_notrace - preempt_schedule called by tracing
|
|
*
|
|
* The tracing infrastructure uses preempt_enable_notrace to prevent
|
|
* recursion and tracing preempt enabling caused by the tracing
|
|
* infrastructure itself. But as tracing can happen in areas coming
|
|
* from userspace or just about to enter userspace, a preempt enable
|
|
* can occur before user_exit() is called. This will cause the scheduler
|
|
* to be called when the system is still in usermode.
|
|
*
|
|
* To prevent this, the preempt_enable_notrace will use this function
|
|
* instead of preempt_schedule() to exit user context if needed before
|
|
* calling the scheduler.
|
|
*/
|
|
asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
|
|
{
|
|
enum ctx_state prev_ctx;
|
|
|
|
if (likely(!preemptible()))
|
|
return;
|
|
|
|
do {
|
|
/*
|
|
* Because the function tracer can trace preempt_count_sub()
|
|
* and it also uses preempt_enable/disable_notrace(), if
|
|
* NEED_RESCHED is set, the preempt_enable_notrace() called
|
|
* by the function tracer will call this function again and
|
|
* cause infinite recursion.
|
|
*
|
|
* Preemption must be disabled here before the function
|
|
* tracer can trace. Break up preempt_disable() into two
|
|
* calls. One to disable preemption without fear of being
|
|
* traced. The other to still record the preemption latency,
|
|
* which can also be traced by the function tracer.
|
|
*/
|
|
preempt_disable_notrace();
|
|
preempt_latency_start(1);
|
|
/*
|
|
* Needs preempt disabled in case user_exit() is traced
|
|
* and the tracer calls preempt_enable_notrace() causing
|
|
* an infinite recursion.
|
|
*/
|
|
prev_ctx = exception_enter();
|
|
__schedule(true);
|
|
exception_exit(prev_ctx);
|
|
|
|
preempt_latency_stop(1);
|
|
preempt_enable_no_resched_notrace();
|
|
} while (need_resched());
|
|
}
|
|
EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
|
|
|
|
#endif /* CONFIG_PREEMPTION */
|
|
|
|
/*
|
|
* This is the entry point to schedule() from kernel preemption
|
|
* off of irq context.
|
|
* Note, that this is called and return with irqs disabled. This will
|
|
* protect us against recursive calling from irq.
|
|
*/
|
|
asmlinkage __visible void __sched preempt_schedule_irq(void)
|
|
{
|
|
enum ctx_state prev_state;
|
|
|
|
/* Catch callers which need to be fixed */
|
|
BUG_ON(preempt_count() || !irqs_disabled());
|
|
|
|
prev_state = exception_enter();
|
|
|
|
do {
|
|
preempt_disable();
|
|
local_irq_enable();
|
|
__schedule(true);
|
|
local_irq_disable();
|
|
sched_preempt_enable_no_resched();
|
|
} while (need_resched());
|
|
|
|
exception_exit(prev_state);
|
|
}
|
|
|
|
int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
|
|
void *key)
|
|
{
|
|
WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
|
|
return try_to_wake_up(curr->private, mode, wake_flags);
|
|
}
|
|
EXPORT_SYMBOL(default_wake_function);
|
|
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
|
|
static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
|
|
{
|
|
if (pi_task)
|
|
prio = min(prio, pi_task->prio);
|
|
|
|
return prio;
|
|
}
|
|
|
|
static inline int rt_effective_prio(struct task_struct *p, int prio)
|
|
{
|
|
struct task_struct *pi_task = rt_mutex_get_top_task(p);
|
|
|
|
return __rt_effective_prio(pi_task, prio);
|
|
}
|
|
|
|
/*
|
|
* rt_mutex_setprio - set the current priority of a task
|
|
* @p: task to boost
|
|
* @pi_task: donor task
|
|
*
|
|
* This function changes the 'effective' priority of a task. It does
|
|
* not touch ->normal_prio like __setscheduler().
|
|
*
|
|
* Used by the rt_mutex code to implement priority inheritance
|
|
* logic. Call site only calls if the priority of the task changed.
|
|
*/
|
|
void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
|
|
{
|
|
int prio, oldprio, queued, running, queue_flag =
|
|
DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
|
|
const struct sched_class *prev_class;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
/* XXX used to be waiter->prio, not waiter->task->prio */
|
|
prio = __rt_effective_prio(pi_task, p->normal_prio);
|
|
|
|
/*
|
|
* If nothing changed; bail early.
|
|
*/
|
|
if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
|
|
return;
|
|
|
|
rq = __task_rq_lock(p, &rf);
|
|
update_rq_clock(rq);
|
|
/*
|
|
* Set under pi_lock && rq->lock, such that the value can be used under
|
|
* either lock.
|
|
*
|
|
* Note that there is loads of tricky to make this pointer cache work
|
|
* right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
|
|
* ensure a task is de-boosted (pi_task is set to NULL) before the
|
|
* task is allowed to run again (and can exit). This ensures the pointer
|
|
* points to a blocked task -- which guaratees the task is present.
|
|
*/
|
|
p->pi_top_task = pi_task;
|
|
|
|
/*
|
|
* For FIFO/RR we only need to set prio, if that matches we're done.
|
|
*/
|
|
if (prio == p->prio && !dl_prio(prio))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* Idle task boosting is a nono in general. There is one
|
|
* exception, when PREEMPT_RT and NOHZ is active:
|
|
*
|
|
* The idle task calls get_next_timer_interrupt() and holds
|
|
* the timer wheel base->lock on the CPU and another CPU wants
|
|
* to access the timer (probably to cancel it). We can safely
|
|
* ignore the boosting request, as the idle CPU runs this code
|
|
* with interrupts disabled and will complete the lock
|
|
* protected section without being interrupted. So there is no
|
|
* real need to boost.
|
|
*/
|
|
if (unlikely(p == rq->idle)) {
|
|
WARN_ON(p != rq->curr);
|
|
WARN_ON(p->pi_blocked_on);
|
|
goto out_unlock;
|
|
}
|
|
|
|
trace_sched_pi_setprio(p, pi_task);
|
|
oldprio = p->prio;
|
|
|
|
if (oldprio == prio)
|
|
queue_flag &= ~DEQUEUE_MOVE;
|
|
|
|
prev_class = p->sched_class;
|
|
queued = task_on_rq_queued(p);
|
|
running = task_current(rq, p);
|
|
if (queued)
|
|
dequeue_task(rq, p, queue_flag);
|
|
if (running)
|
|
put_prev_task(rq, p);
|
|
|
|
/*
|
|
* Boosting condition are:
|
|
* 1. -rt task is running and holds mutex A
|
|
* --> -dl task blocks on mutex A
|
|
*
|
|
* 2. -dl task is running and holds mutex A
|
|
* --> -dl task blocks on mutex A and could preempt the
|
|
* running task
|
|
*/
|
|
if (dl_prio(prio)) {
|
|
if (!dl_prio(p->normal_prio) ||
|
|
(pi_task && dl_prio(pi_task->prio) &&
|
|
dl_entity_preempt(&pi_task->dl, &p->dl))) {
|
|
p->dl.pi_se = pi_task->dl.pi_se;
|
|
queue_flag |= ENQUEUE_REPLENISH;
|
|
} else {
|
|
p->dl.pi_se = &p->dl;
|
|
}
|
|
p->sched_class = &dl_sched_class;
|
|
} else if (rt_prio(prio)) {
|
|
if (dl_prio(oldprio))
|
|
p->dl.pi_se = &p->dl;
|
|
if (oldprio < prio)
|
|
queue_flag |= ENQUEUE_HEAD;
|
|
p->sched_class = &rt_sched_class;
|
|
} else {
|
|
if (dl_prio(oldprio))
|
|
p->dl.pi_se = &p->dl;
|
|
if (rt_prio(oldprio))
|
|
p->rt.timeout = 0;
|
|
p->sched_class = &fair_sched_class;
|
|
}
|
|
|
|
p->prio = prio;
|
|
|
|
if (queued)
|
|
enqueue_task(rq, p, queue_flag);
|
|
if (running)
|
|
set_next_task(rq, p);
|
|
|
|
check_class_changed(rq, p, prev_class, oldprio);
|
|
out_unlock:
|
|
/* Avoid rq from going away on us: */
|
|
preempt_disable();
|
|
__task_rq_unlock(rq, &rf);
|
|
|
|
balance_callback(rq);
|
|
preempt_enable();
|
|
}
|
|
#else
|
|
static inline int rt_effective_prio(struct task_struct *p, int prio)
|
|
{
|
|
return prio;
|
|
}
|
|
#endif
|
|
|
|
void set_user_nice(struct task_struct *p, long nice)
|
|
{
|
|
bool queued, running;
|
|
int old_prio;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
|
|
return;
|
|
/*
|
|
* We have to be careful, if called from sys_setpriority(),
|
|
* the task might be in the middle of scheduling on another CPU.
|
|
*/
|
|
rq = task_rq_lock(p, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
/*
|
|
* The RT priorities are set via sched_setscheduler(), but we still
|
|
* allow the 'normal' nice value to be set - but as expected
|
|
* it wont have any effect on scheduling until the task is
|
|
* SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
|
|
*/
|
|
if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
goto out_unlock;
|
|
}
|
|
queued = task_on_rq_queued(p);
|
|
running = task_current(rq, p);
|
|
if (queued)
|
|
dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
|
|
if (running)
|
|
put_prev_task(rq, p);
|
|
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
set_load_weight(p, true);
|
|
old_prio = p->prio;
|
|
p->prio = effective_prio(p);
|
|
|
|
if (queued)
|
|
enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
|
|
if (running)
|
|
set_next_task(rq, p);
|
|
|
|
/*
|
|
* If the task increased its priority or is running and
|
|
* lowered its priority, then reschedule its CPU:
|
|
*/
|
|
p->sched_class->prio_changed(rq, p, old_prio);
|
|
|
|
out_unlock:
|
|
task_rq_unlock(rq, p, &rf);
|
|
}
|
|
EXPORT_SYMBOL(set_user_nice);
|
|
|
|
/*
|
|
* can_nice - check if a task can reduce its nice value
|
|
* @p: task
|
|
* @nice: nice value
|
|
*/
|
|
int can_nice(const struct task_struct *p, const int nice)
|
|
{
|
|
/* Convert nice value [19,-20] to rlimit style value [1,40]: */
|
|
int nice_rlim = nice_to_rlimit(nice);
|
|
|
|
return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
|
|
capable(CAP_SYS_NICE));
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_NICE
|
|
|
|
/*
|
|
* sys_nice - change the priority of the current process.
|
|
* @increment: priority increment
|
|
*
|
|
* sys_setpriority is a more generic, but much slower function that
|
|
* does similar things.
|
|
*/
|
|
SYSCALL_DEFINE1(nice, int, increment)
|
|
{
|
|
long nice, retval;
|
|
|
|
/*
|
|
* Setpriority might change our priority at the same moment.
|
|
* We don't have to worry. Conceptually one call occurs first
|
|
* and we have a single winner.
|
|
*/
|
|
increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
|
|
nice = task_nice(current) + increment;
|
|
|
|
nice = clamp_val(nice, MIN_NICE, MAX_NICE);
|
|
if (increment < 0 && !can_nice(current, nice))
|
|
return -EPERM;
|
|
|
|
retval = security_task_setnice(current, nice);
|
|
if (retval)
|
|
return retval;
|
|
|
|
set_user_nice(current, nice);
|
|
return 0;
|
|
}
|
|
|
|
#endif
|
|
|
|
/**
|
|
* task_prio - return the priority value of a given task.
|
|
* @p: the task in question.
|
|
*
|
|
* Return: The priority value as seen by users in /proc.
|
|
* RT tasks are offset by -200. Normal tasks are centered
|
|
* around 0, value goes from -16 to +15.
|
|
*/
|
|
int task_prio(const struct task_struct *p)
|
|
{
|
|
return p->prio - MAX_RT_PRIO;
|
|
}
|
|
|
|
/**
|
|
* idle_cpu - is a given CPU idle currently?
|
|
* @cpu: the processor in question.
|
|
*
|
|
* Return: 1 if the CPU is currently idle. 0 otherwise.
|
|
*/
|
|
int idle_cpu(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (rq->curr != rq->idle)
|
|
return 0;
|
|
|
|
if (rq->nr_running)
|
|
return 0;
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (rq->ttwu_pending)
|
|
return 0;
|
|
#endif
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* available_idle_cpu - is a given CPU idle for enqueuing work.
|
|
* @cpu: the CPU in question.
|
|
*
|
|
* Return: 1 if the CPU is currently idle. 0 otherwise.
|
|
*/
|
|
int available_idle_cpu(int cpu)
|
|
{
|
|
if (!idle_cpu(cpu))
|
|
return 0;
|
|
|
|
if (vcpu_is_preempted(cpu))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* idle_task - return the idle task for a given CPU.
|
|
* @cpu: the processor in question.
|
|
*
|
|
* Return: The idle task for the CPU @cpu.
|
|
*/
|
|
struct task_struct *idle_task(int cpu)
|
|
{
|
|
return cpu_rq(cpu)->idle;
|
|
}
|
|
|
|
/**
|
|
* find_process_by_pid - find a process with a matching PID value.
|
|
* @pid: the pid in question.
|
|
*
|
|
* The task of @pid, if found. %NULL otherwise.
|
|
*/
|
|
static struct task_struct *find_process_by_pid(pid_t pid)
|
|
{
|
|
return pid ? find_task_by_vpid(pid) : current;
|
|
}
|
|
|
|
/*
|
|
* sched_setparam() passes in -1 for its policy, to let the functions
|
|
* it calls know not to change it.
|
|
*/
|
|
#define SETPARAM_POLICY -1
|
|
|
|
static void __setscheduler_params(struct task_struct *p,
|
|
const struct sched_attr *attr)
|
|
{
|
|
int policy = attr->sched_policy;
|
|
|
|
if (policy == SETPARAM_POLICY)
|
|
policy = p->policy;
|
|
|
|
p->policy = policy;
|
|
|
|
if (dl_policy(policy))
|
|
__setparam_dl(p, attr);
|
|
else if (fair_policy(policy))
|
|
p->static_prio = NICE_TO_PRIO(attr->sched_nice);
|
|
|
|
/*
|
|
* __sched_setscheduler() ensures attr->sched_priority == 0 when
|
|
* !rt_policy. Always setting this ensures that things like
|
|
* getparam()/getattr() don't report silly values for !rt tasks.
|
|
*/
|
|
p->rt_priority = attr->sched_priority;
|
|
p->normal_prio = normal_prio(p);
|
|
set_load_weight(p, true);
|
|
}
|
|
|
|
/* Actually do priority change: must hold pi & rq lock. */
|
|
static void __setscheduler(struct rq *rq, struct task_struct *p,
|
|
const struct sched_attr *attr, bool keep_boost)
|
|
{
|
|
/*
|
|
* If params can't change scheduling class changes aren't allowed
|
|
* either.
|
|
*/
|
|
if (attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)
|
|
return;
|
|
|
|
__setscheduler_params(p, attr);
|
|
|
|
/*
|
|
* Keep a potential priority boosting if called from
|
|
* sched_setscheduler().
|
|
*/
|
|
p->prio = normal_prio(p);
|
|
if (keep_boost)
|
|
p->prio = rt_effective_prio(p, p->prio);
|
|
|
|
if (dl_prio(p->prio))
|
|
p->sched_class = &dl_sched_class;
|
|
else if (rt_prio(p->prio))
|
|
p->sched_class = &rt_sched_class;
|
|
else
|
|
p->sched_class = &fair_sched_class;
|
|
}
|
|
|
|
/*
|
|
* Check the target process has a UID that matches the current process's:
|
|
*/
|
|
static bool check_same_owner(struct task_struct *p)
|
|
{
|
|
const struct cred *cred = current_cred(), *pcred;
|
|
bool match;
|
|
|
|
rcu_read_lock();
|
|
pcred = __task_cred(p);
|
|
match = (uid_eq(cred->euid, pcred->euid) ||
|
|
uid_eq(cred->euid, pcred->uid));
|
|
rcu_read_unlock();
|
|
return match;
|
|
}
|
|
|
|
static int __sched_setscheduler(struct task_struct *p,
|
|
const struct sched_attr *attr,
|
|
bool user, bool pi)
|
|
{
|
|
int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
|
|
MAX_RT_PRIO - 1 - attr->sched_priority;
|
|
int retval, oldprio, oldpolicy = -1, queued, running;
|
|
int new_effective_prio, policy = attr->sched_policy;
|
|
const struct sched_class *prev_class;
|
|
struct rq_flags rf;
|
|
int reset_on_fork;
|
|
int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
|
|
struct rq *rq;
|
|
|
|
/* The pi code expects interrupts enabled */
|
|
BUG_ON(pi && in_interrupt());
|
|
recheck:
|
|
/* Double check policy once rq lock held: */
|
|
if (policy < 0) {
|
|
reset_on_fork = p->sched_reset_on_fork;
|
|
policy = oldpolicy = p->policy;
|
|
} else {
|
|
reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
|
|
|
|
if (!valid_policy(policy))
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Valid priorities for SCHED_FIFO and SCHED_RR are
|
|
* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
|
|
* SCHED_BATCH and SCHED_IDLE is 0.
|
|
*/
|
|
if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
|
|
(!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
|
|
return -EINVAL;
|
|
if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
|
|
(rt_policy(policy) != (attr->sched_priority != 0)))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Allow unprivileged RT tasks to decrease priority:
|
|
*/
|
|
if (user && !capable(CAP_SYS_NICE)) {
|
|
if (fair_policy(policy)) {
|
|
if (attr->sched_nice < task_nice(p) &&
|
|
!can_nice(p, attr->sched_nice))
|
|
return -EPERM;
|
|
}
|
|
|
|
if (rt_policy(policy)) {
|
|
unsigned long rlim_rtprio =
|
|
task_rlimit(p, RLIMIT_RTPRIO);
|
|
|
|
/* Can't set/change the rt policy: */
|
|
if (policy != p->policy && !rlim_rtprio)
|
|
return -EPERM;
|
|
|
|
/* Can't increase priority: */
|
|
if (attr->sched_priority > p->rt_priority &&
|
|
attr->sched_priority > rlim_rtprio)
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* Can't set/change SCHED_DEADLINE policy at all for now
|
|
* (safest behavior); in the future we would like to allow
|
|
* unprivileged DL tasks to increase their relative deadline
|
|
* or reduce their runtime (both ways reducing utilization)
|
|
*/
|
|
if (dl_policy(policy))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* Treat SCHED_IDLE as nice 20. Only allow a switch to
|
|
* SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
|
|
*/
|
|
if (task_has_idle_policy(p) && !idle_policy(policy)) {
|
|
if (!can_nice(p, task_nice(p)))
|
|
return -EPERM;
|
|
}
|
|
|
|
/* Can't change other user's priorities: */
|
|
if (!check_same_owner(p))
|
|
return -EPERM;
|
|
|
|
/* Normal users shall not reset the sched_reset_on_fork flag: */
|
|
if (p->sched_reset_on_fork && !reset_on_fork)
|
|
return -EPERM;
|
|
}
|
|
|
|
if (user) {
|
|
if (attr->sched_flags & SCHED_FLAG_SUGOV)
|
|
return -EINVAL;
|
|
|
|
retval = security_task_setscheduler(p);
|
|
if (retval)
|
|
return retval;
|
|
}
|
|
|
|
/* Update task specific "requested" clamps */
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) {
|
|
retval = uclamp_validate(p, attr);
|
|
if (retval)
|
|
return retval;
|
|
}
|
|
|
|
if (pi)
|
|
cpuset_read_lock();
|
|
|
|
/*
|
|
* Make sure no PI-waiters arrive (or leave) while we are
|
|
* changing the priority of the task:
|
|
*
|
|
* To be able to change p->policy safely, the appropriate
|
|
* runqueue lock must be held.
|
|
*/
|
|
rq = task_rq_lock(p, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
/*
|
|
* Changing the policy of the stop threads its a very bad idea:
|
|
*/
|
|
if (p == rq->stop) {
|
|
retval = -EINVAL;
|
|
goto unlock;
|
|
}
|
|
|
|
/*
|
|
* If not changing anything there's no need to proceed further,
|
|
* but store a possible modification of reset_on_fork.
|
|
*/
|
|
if (unlikely(policy == p->policy)) {
|
|
if (fair_policy(policy) && attr->sched_nice != task_nice(p))
|
|
goto change;
|
|
if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
|
|
goto change;
|
|
if (dl_policy(policy) && dl_param_changed(p, attr))
|
|
goto change;
|
|
if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)
|
|
goto change;
|
|
|
|
p->sched_reset_on_fork = reset_on_fork;
|
|
retval = 0;
|
|
goto unlock;
|
|
}
|
|
change:
|
|
|
|
if (user) {
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Do not allow realtime tasks into groups that have no runtime
|
|
* assigned.
|
|
*/
|
|
if (rt_bandwidth_enabled() && rt_policy(policy) &&
|
|
task_group(p)->rt_bandwidth.rt_runtime == 0 &&
|
|
!task_group_is_autogroup(task_group(p))) {
|
|
retval = -EPERM;
|
|
goto unlock;
|
|
}
|
|
#endif
|
|
#ifdef CONFIG_SMP
|
|
if (dl_bandwidth_enabled() && dl_policy(policy) &&
|
|
!(attr->sched_flags & SCHED_FLAG_SUGOV)) {
|
|
cpumask_t *span = rq->rd->span;
|
|
|
|
/*
|
|
* Don't allow tasks with an affinity mask smaller than
|
|
* the entire root_domain to become SCHED_DEADLINE. We
|
|
* will also fail if there's no bandwidth available.
|
|
*/
|
|
if (!cpumask_subset(span, p->cpus_ptr) ||
|
|
rq->rd->dl_bw.bw == 0) {
|
|
retval = -EPERM;
|
|
goto unlock;
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/* Re-check policy now with rq lock held: */
|
|
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
|
|
policy = oldpolicy = -1;
|
|
task_rq_unlock(rq, p, &rf);
|
|
if (pi)
|
|
cpuset_read_unlock();
|
|
goto recheck;
|
|
}
|
|
|
|
/*
|
|
* If setscheduling to SCHED_DEADLINE (or changing the parameters
|
|
* of a SCHED_DEADLINE task) we need to check if enough bandwidth
|
|
* is available.
|
|
*/
|
|
if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
|
|
retval = -EBUSY;
|
|
goto unlock;
|
|
}
|
|
|
|
p->sched_reset_on_fork = reset_on_fork;
|
|
oldprio = p->prio;
|
|
|
|
if (pi) {
|
|
/*
|
|
* Take priority boosted tasks into account. If the new
|
|
* effective priority is unchanged, we just store the new
|
|
* normal parameters and do not touch the scheduler class and
|
|
* the runqueue. This will be done when the task deboost
|
|
* itself.
|
|
*/
|
|
new_effective_prio = rt_effective_prio(p, newprio);
|
|
if (new_effective_prio == oldprio)
|
|
queue_flags &= ~DEQUEUE_MOVE;
|
|
}
|
|
|
|
queued = task_on_rq_queued(p);
|
|
running = task_current(rq, p);
|
|
if (queued)
|
|
dequeue_task(rq, p, queue_flags);
|
|
if (running)
|
|
put_prev_task(rq, p);
|
|
|
|
prev_class = p->sched_class;
|
|
|
|
__setscheduler(rq, p, attr, pi);
|
|
__setscheduler_uclamp(p, attr);
|
|
|
|
if (queued) {
|
|
/*
|
|
* We enqueue to tail when the priority of a task is
|
|
* increased (user space view).
|
|
*/
|
|
if (oldprio < p->prio)
|
|
queue_flags |= ENQUEUE_HEAD;
|
|
|
|
enqueue_task(rq, p, queue_flags);
|
|
}
|
|
if (running)
|
|
set_next_task(rq, p);
|
|
|
|
check_class_changed(rq, p, prev_class, oldprio);
|
|
|
|
/* Avoid rq from going away on us: */
|
|
preempt_disable();
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
if (pi) {
|
|
cpuset_read_unlock();
|
|
rt_mutex_adjust_pi(p);
|
|
}
|
|
|
|
/* Run balance callbacks after we've adjusted the PI chain: */
|
|
balance_callback(rq);
|
|
preempt_enable();
|
|
|
|
return 0;
|
|
|
|
unlock:
|
|
task_rq_unlock(rq, p, &rf);
|
|
if (pi)
|
|
cpuset_read_unlock();
|
|
return retval;
|
|
}
|
|
|
|
static int _sched_setscheduler(struct task_struct *p, int policy,
|
|
const struct sched_param *param, bool check)
|
|
{
|
|
struct sched_attr attr = {
|
|
.sched_policy = policy,
|
|
.sched_priority = param->sched_priority,
|
|
.sched_nice = PRIO_TO_NICE(p->static_prio),
|
|
};
|
|
|
|
/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
|
|
if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
|
|
attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
|
|
policy &= ~SCHED_RESET_ON_FORK;
|
|
attr.sched_policy = policy;
|
|
}
|
|
|
|
return __sched_setscheduler(p, &attr, check, true);
|
|
}
|
|
/**
|
|
* sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
|
|
* @p: the task in question.
|
|
* @policy: new policy.
|
|
* @param: structure containing the new RT priority.
|
|
*
|
|
* Use sched_set_fifo(), read its comment.
|
|
*
|
|
* Return: 0 on success. An error code otherwise.
|
|
*
|
|
* NOTE that the task may be already dead.
|
|
*/
|
|
int sched_setscheduler(struct task_struct *p, int policy,
|
|
const struct sched_param *param)
|
|
{
|
|
return _sched_setscheduler(p, policy, param, true);
|
|
}
|
|
|
|
int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
|
|
{
|
|
return __sched_setscheduler(p, attr, true, true);
|
|
}
|
|
|
|
int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
|
|
{
|
|
return __sched_setscheduler(p, attr, false, true);
|
|
}
|
|
|
|
/**
|
|
* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
|
|
* @p: the task in question.
|
|
* @policy: new policy.
|
|
* @param: structure containing the new RT priority.
|
|
*
|
|
* Just like sched_setscheduler, only don't bother checking if the
|
|
* current context has permission. For example, this is needed in
|
|
* stop_machine(): we create temporary high priority worker threads,
|
|
* but our caller might not have that capability.
|
|
*
|
|
* Return: 0 on success. An error code otherwise.
|
|
*/
|
|
int sched_setscheduler_nocheck(struct task_struct *p, int policy,
|
|
const struct sched_param *param)
|
|
{
|
|
return _sched_setscheduler(p, policy, param, false);
|
|
}
|
|
|
|
/*
|
|
* SCHED_FIFO is a broken scheduler model; that is, it is fundamentally
|
|
* incapable of resource management, which is the one thing an OS really should
|
|
* be doing.
|
|
*
|
|
* This is of course the reason it is limited to privileged users only.
|
|
*
|
|
* Worse still; it is fundamentally impossible to compose static priority
|
|
* workloads. You cannot take two correctly working static prio workloads
|
|
* and smash them together and still expect them to work.
|
|
*
|
|
* For this reason 'all' FIFO tasks the kernel creates are basically at:
|
|
*
|
|
* MAX_RT_PRIO / 2
|
|
*
|
|
* The administrator _MUST_ configure the system, the kernel simply doesn't
|
|
* know enough information to make a sensible choice.
|
|
*/
|
|
void sched_set_fifo(struct task_struct *p)
|
|
{
|
|
struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 };
|
|
WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_set_fifo);
|
|
|
|
/*
|
|
* For when you don't much care about FIFO, but want to be above SCHED_NORMAL.
|
|
*/
|
|
void sched_set_fifo_low(struct task_struct *p)
|
|
{
|
|
struct sched_param sp = { .sched_priority = 1 };
|
|
WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_set_fifo_low);
|
|
|
|
void sched_set_normal(struct task_struct *p, int nice)
|
|
{
|
|
struct sched_attr attr = {
|
|
.sched_policy = SCHED_NORMAL,
|
|
.sched_nice = nice,
|
|
};
|
|
WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_set_normal);
|
|
|
|
static int
|
|
do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
|
|
{
|
|
struct sched_param lparam;
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
if (!param || pid < 0)
|
|
return -EINVAL;
|
|
if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
|
|
return -EFAULT;
|
|
|
|
rcu_read_lock();
|
|
retval = -ESRCH;
|
|
p = find_process_by_pid(pid);
|
|
if (likely(p))
|
|
get_task_struct(p);
|
|
rcu_read_unlock();
|
|
|
|
if (likely(p)) {
|
|
retval = sched_setscheduler(p, policy, &lparam);
|
|
put_task_struct(p);
|
|
}
|
|
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Mimics kernel/events/core.c perf_copy_attr().
|
|
*/
|
|
static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
|
|
{
|
|
u32 size;
|
|
int ret;
|
|
|
|
/* Zero the full structure, so that a short copy will be nice: */
|
|
memset(attr, 0, sizeof(*attr));
|
|
|
|
ret = get_user(size, &uattr->size);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/* ABI compatibility quirk: */
|
|
if (!size)
|
|
size = SCHED_ATTR_SIZE_VER0;
|
|
if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE)
|
|
goto err_size;
|
|
|
|
ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
|
|
if (ret) {
|
|
if (ret == -E2BIG)
|
|
goto err_size;
|
|
return ret;
|
|
}
|
|
|
|
if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) &&
|
|
size < SCHED_ATTR_SIZE_VER1)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* XXX: Do we want to be lenient like existing syscalls; or do we want
|
|
* to be strict and return an error on out-of-bounds values?
|
|
*/
|
|
attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
|
|
|
|
return 0;
|
|
|
|
err_size:
|
|
put_user(sizeof(*attr), &uattr->size);
|
|
return -E2BIG;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setscheduler - set/change the scheduler policy and RT priority
|
|
* @pid: the pid in question.
|
|
* @policy: new policy.
|
|
* @param: structure containing the new RT priority.
|
|
*
|
|
* Return: 0 on success. An error code otherwise.
|
|
*/
|
|
SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
|
|
{
|
|
if (policy < 0)
|
|
return -EINVAL;
|
|
|
|
return do_sched_setscheduler(pid, policy, param);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setparam - set/change the RT priority of a thread
|
|
* @pid: the pid in question.
|
|
* @param: structure containing the new RT priority.
|
|
*
|
|
* Return: 0 on success. An error code otherwise.
|
|
*/
|
|
SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
|
|
{
|
|
return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setattr - same as above, but with extended sched_attr
|
|
* @pid: the pid in question.
|
|
* @uattr: structure containing the extended parameters.
|
|
* @flags: for future extension.
|
|
*/
|
|
SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
|
|
unsigned int, flags)
|
|
{
|
|
struct sched_attr attr;
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
if (!uattr || pid < 0 || flags)
|
|
return -EINVAL;
|
|
|
|
retval = sched_copy_attr(uattr, &attr);
|
|
if (retval)
|
|
return retval;
|
|
|
|
if ((int)attr.sched_policy < 0)
|
|
return -EINVAL;
|
|
if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY)
|
|
attr.sched_policy = SETPARAM_POLICY;
|
|
|
|
rcu_read_lock();
|
|
retval = -ESRCH;
|
|
p = find_process_by_pid(pid);
|
|
if (likely(p))
|
|
get_task_struct(p);
|
|
rcu_read_unlock();
|
|
|
|
if (likely(p)) {
|
|
retval = sched_setattr(p, &attr);
|
|
put_task_struct(p);
|
|
}
|
|
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
|
|
* @pid: the pid in question.
|
|
*
|
|
* Return: On success, the policy of the thread. Otherwise, a negative error
|
|
* code.
|
|
*/
|
|
SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
|
|
{
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
if (pid < 0)
|
|
return -EINVAL;
|
|
|
|
retval = -ESRCH;
|
|
rcu_read_lock();
|
|
p = find_process_by_pid(pid);
|
|
if (p) {
|
|
retval = security_task_getscheduler(p);
|
|
if (!retval)
|
|
retval = p->policy
|
|
| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
|
|
}
|
|
rcu_read_unlock();
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getparam - get the RT priority of a thread
|
|
* @pid: the pid in question.
|
|
* @param: structure containing the RT priority.
|
|
*
|
|
* Return: On success, 0 and the RT priority is in @param. Otherwise, an error
|
|
* code.
|
|
*/
|
|
SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
|
|
{
|
|
struct sched_param lp = { .sched_priority = 0 };
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
if (!param || pid < 0)
|
|
return -EINVAL;
|
|
|
|
rcu_read_lock();
|
|
p = find_process_by_pid(pid);
|
|
retval = -ESRCH;
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
if (task_has_rt_policy(p))
|
|
lp.sched_priority = p->rt_priority;
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* This one might sleep, we cannot do it with a spinlock held ...
|
|
*/
|
|
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
|
|
|
|
return retval;
|
|
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* Copy the kernel size attribute structure (which might be larger
|
|
* than what user-space knows about) to user-space.
|
|
*
|
|
* Note that all cases are valid: user-space buffer can be larger or
|
|
* smaller than the kernel-space buffer. The usual case is that both
|
|
* have the same size.
|
|
*/
|
|
static int
|
|
sched_attr_copy_to_user(struct sched_attr __user *uattr,
|
|
struct sched_attr *kattr,
|
|
unsigned int usize)
|
|
{
|
|
unsigned int ksize = sizeof(*kattr);
|
|
|
|
if (!access_ok(uattr, usize))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* sched_getattr() ABI forwards and backwards compatibility:
|
|
*
|
|
* If usize == ksize then we just copy everything to user-space and all is good.
|
|
*
|
|
* If usize < ksize then we only copy as much as user-space has space for,
|
|
* this keeps ABI compatibility as well. We skip the rest.
|
|
*
|
|
* If usize > ksize then user-space is using a newer version of the ABI,
|
|
* which part the kernel doesn't know about. Just ignore it - tooling can
|
|
* detect the kernel's knowledge of attributes from the attr->size value
|
|
* which is set to ksize in this case.
|
|
*/
|
|
kattr->size = min(usize, ksize);
|
|
|
|
if (copy_to_user(uattr, kattr, kattr->size))
|
|
return -EFAULT;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getattr - similar to sched_getparam, but with sched_attr
|
|
* @pid: the pid in question.
|
|
* @uattr: structure containing the extended parameters.
|
|
* @usize: sizeof(attr) for fwd/bwd comp.
|
|
* @flags: for future extension.
|
|
*/
|
|
SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
|
|
unsigned int, usize, unsigned int, flags)
|
|
{
|
|
struct sched_attr kattr = { };
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
if (!uattr || pid < 0 || usize > PAGE_SIZE ||
|
|
usize < SCHED_ATTR_SIZE_VER0 || flags)
|
|
return -EINVAL;
|
|
|
|
rcu_read_lock();
|
|
p = find_process_by_pid(pid);
|
|
retval = -ESRCH;
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
kattr.sched_policy = p->policy;
|
|
if (p->sched_reset_on_fork)
|
|
kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
|
|
if (task_has_dl_policy(p))
|
|
__getparam_dl(p, &kattr);
|
|
else if (task_has_rt_policy(p))
|
|
kattr.sched_priority = p->rt_priority;
|
|
else
|
|
kattr.sched_nice = task_nice(p);
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK
|
|
/*
|
|
* This could race with another potential updater, but this is fine
|
|
* because it'll correctly read the old or the new value. We don't need
|
|
* to guarantee who wins the race as long as it doesn't return garbage.
|
|
*/
|
|
kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value;
|
|
kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value;
|
|
#endif
|
|
|
|
rcu_read_unlock();
|
|
|
|
return sched_attr_copy_to_user(uattr, &kattr, usize);
|
|
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
return retval;
|
|
}
|
|
|
|
long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
|
|
{
|
|
cpumask_var_t cpus_allowed, new_mask;
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
rcu_read_lock();
|
|
|
|
p = find_process_by_pid(pid);
|
|
if (!p) {
|
|
rcu_read_unlock();
|
|
return -ESRCH;
|
|
}
|
|
|
|
/* Prevent p going away */
|
|
get_task_struct(p);
|
|
rcu_read_unlock();
|
|
|
|
if (p->flags & PF_NO_SETAFFINITY) {
|
|
retval = -EINVAL;
|
|
goto out_put_task;
|
|
}
|
|
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
|
|
retval = -ENOMEM;
|
|
goto out_put_task;
|
|
}
|
|
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
|
|
retval = -ENOMEM;
|
|
goto out_free_cpus_allowed;
|
|
}
|
|
retval = -EPERM;
|
|
if (!check_same_owner(p)) {
|
|
rcu_read_lock();
|
|
if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
|
|
rcu_read_unlock();
|
|
goto out_free_new_mask;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
retval = security_task_setscheduler(p);
|
|
if (retval)
|
|
goto out_free_new_mask;
|
|
|
|
|
|
cpuset_cpus_allowed(p, cpus_allowed);
|
|
cpumask_and(new_mask, in_mask, cpus_allowed);
|
|
|
|
/*
|
|
* Since bandwidth control happens on root_domain basis,
|
|
* if admission test is enabled, we only admit -deadline
|
|
* tasks allowed to run on all the CPUs in the task's
|
|
* root_domain.
|
|
*/
|
|
#ifdef CONFIG_SMP
|
|
if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
|
|
rcu_read_lock();
|
|
if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
|
|
retval = -EBUSY;
|
|
rcu_read_unlock();
|
|
goto out_free_new_mask;
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
#endif
|
|
again:
|
|
retval = __set_cpus_allowed_ptr(p, new_mask, true);
|
|
|
|
if (!retval) {
|
|
cpuset_cpus_allowed(p, cpus_allowed);
|
|
if (!cpumask_subset(new_mask, cpus_allowed)) {
|
|
/*
|
|
* We must have raced with a concurrent cpuset
|
|
* update. Just reset the cpus_allowed to the
|
|
* cpuset's cpus_allowed
|
|
*/
|
|
cpumask_copy(new_mask, cpus_allowed);
|
|
goto again;
|
|
}
|
|
}
|
|
out_free_new_mask:
|
|
free_cpumask_var(new_mask);
|
|
out_free_cpus_allowed:
|
|
free_cpumask_var(cpus_allowed);
|
|
out_put_task:
|
|
put_task_struct(p);
|
|
return retval;
|
|
}
|
|
|
|
static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
|
|
struct cpumask *new_mask)
|
|
{
|
|
if (len < cpumask_size())
|
|
cpumask_clear(new_mask);
|
|
else if (len > cpumask_size())
|
|
len = cpumask_size();
|
|
|
|
return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_setaffinity - set the CPU affinity of a process
|
|
* @pid: pid of the process
|
|
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
|
|
* @user_mask_ptr: user-space pointer to the new CPU mask
|
|
*
|
|
* Return: 0 on success. An error code otherwise.
|
|
*/
|
|
SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
|
|
unsigned long __user *, user_mask_ptr)
|
|
{
|
|
cpumask_var_t new_mask;
|
|
int retval;
|
|
|
|
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
|
|
return -ENOMEM;
|
|
|
|
retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
|
|
if (retval == 0)
|
|
retval = sched_setaffinity(pid, new_mask);
|
|
free_cpumask_var(new_mask);
|
|
return retval;
|
|
}
|
|
|
|
long sched_getaffinity(pid_t pid, struct cpumask *mask)
|
|
{
|
|
struct task_struct *p;
|
|
unsigned long flags;
|
|
int retval;
|
|
|
|
rcu_read_lock();
|
|
|
|
retval = -ESRCH;
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
raw_spin_lock_irqsave(&p->pi_lock, flags);
|
|
cpumask_and(mask, &p->cpus_mask, cpu_active_mask);
|
|
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getaffinity - get the CPU affinity of a process
|
|
* @pid: pid of the process
|
|
* @len: length in bytes of the bitmask pointed to by user_mask_ptr
|
|
* @user_mask_ptr: user-space pointer to hold the current CPU mask
|
|
*
|
|
* Return: size of CPU mask copied to user_mask_ptr on success. An
|
|
* error code otherwise.
|
|
*/
|
|
SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
|
|
unsigned long __user *, user_mask_ptr)
|
|
{
|
|
int ret;
|
|
cpumask_var_t mask;
|
|
|
|
if ((len * BITS_PER_BYTE) < nr_cpu_ids)
|
|
return -EINVAL;
|
|
if (len & (sizeof(unsigned long)-1))
|
|
return -EINVAL;
|
|
|
|
if (!alloc_cpumask_var(&mask, GFP_KERNEL))
|
|
return -ENOMEM;
|
|
|
|
ret = sched_getaffinity(pid, mask);
|
|
if (ret == 0) {
|
|
unsigned int retlen = min(len, cpumask_size());
|
|
|
|
if (copy_to_user(user_mask_ptr, mask, retlen))
|
|
ret = -EFAULT;
|
|
else
|
|
ret = retlen;
|
|
}
|
|
free_cpumask_var(mask);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_yield - yield the current processor to other threads.
|
|
*
|
|
* This function yields the current CPU to other tasks. If there are no
|
|
* other threads running on this CPU then this function will return.
|
|
*
|
|
* Return: 0.
|
|
*/
|
|
static void do_sched_yield(void)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = this_rq_lock_irq(&rf);
|
|
|
|
schedstat_inc(rq->yld_count);
|
|
current->sched_class->yield_task(rq);
|
|
|
|
/*
|
|
* Since we are going to call schedule() anyway, there's
|
|
* no need to preempt or enable interrupts:
|
|
*/
|
|
preempt_disable();
|
|
rq_unlock(rq, &rf);
|
|
sched_preempt_enable_no_resched();
|
|
|
|
schedule();
|
|
}
|
|
|
|
SYSCALL_DEFINE0(sched_yield)
|
|
{
|
|
do_sched_yield();
|
|
return 0;
|
|
}
|
|
|
|
#ifndef CONFIG_PREEMPTION
|
|
int __sched _cond_resched(void)
|
|
{
|
|
if (should_resched(0)) {
|
|
preempt_schedule_common();
|
|
return 1;
|
|
}
|
|
rcu_all_qs();
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(_cond_resched);
|
|
#endif
|
|
|
|
/*
|
|
* __cond_resched_lock() - if a reschedule is pending, drop the given lock,
|
|
* call schedule, and on return reacquire the lock.
|
|
*
|
|
* This works OK both with and without CONFIG_PREEMPTION. We do strange low-level
|
|
* operations here to prevent schedule() from being called twice (once via
|
|
* spin_unlock(), once by hand).
|
|
*/
|
|
int __cond_resched_lock(spinlock_t *lock)
|
|
{
|
|
int resched = should_resched(PREEMPT_LOCK_OFFSET);
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(lock);
|
|
|
|
if (spin_needbreak(lock) || resched) {
|
|
spin_unlock(lock);
|
|
if (resched)
|
|
preempt_schedule_common();
|
|
else
|
|
cpu_relax();
|
|
ret = 1;
|
|
spin_lock(lock);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(__cond_resched_lock);
|
|
|
|
/**
|
|
* yield - yield the current processor to other threads.
|
|
*
|
|
* Do not ever use this function, there's a 99% chance you're doing it wrong.
|
|
*
|
|
* The scheduler is at all times free to pick the calling task as the most
|
|
* eligible task to run, if removing the yield() call from your code breaks
|
|
* it, its already broken.
|
|
*
|
|
* Typical broken usage is:
|
|
*
|
|
* while (!event)
|
|
* yield();
|
|
*
|
|
* where one assumes that yield() will let 'the other' process run that will
|
|
* make event true. If the current task is a SCHED_FIFO task that will never
|
|
* happen. Never use yield() as a progress guarantee!!
|
|
*
|
|
* If you want to use yield() to wait for something, use wait_event().
|
|
* If you want to use yield() to be 'nice' for others, use cond_resched().
|
|
* If you still want to use yield(), do not!
|
|
*/
|
|
void __sched yield(void)
|
|
{
|
|
set_current_state(TASK_RUNNING);
|
|
do_sched_yield();
|
|
}
|
|
EXPORT_SYMBOL(yield);
|
|
|
|
/**
|
|
* yield_to - yield the current processor to another thread in
|
|
* your thread group, or accelerate that thread toward the
|
|
* processor it's on.
|
|
* @p: target task
|
|
* @preempt: whether task preemption is allowed or not
|
|
*
|
|
* It's the caller's job to ensure that the target task struct
|
|
* can't go away on us before we can do any checks.
|
|
*
|
|
* Return:
|
|
* true (>0) if we indeed boosted the target task.
|
|
* false (0) if we failed to boost the target.
|
|
* -ESRCH if there's no task to yield to.
|
|
*/
|
|
int __sched yield_to(struct task_struct *p, bool preempt)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct rq *rq, *p_rq;
|
|
unsigned long flags;
|
|
int yielded = 0;
|
|
|
|
local_irq_save(flags);
|
|
rq = this_rq();
|
|
|
|
again:
|
|
p_rq = task_rq(p);
|
|
/*
|
|
* If we're the only runnable task on the rq and target rq also
|
|
* has only one task, there's absolutely no point in yielding.
|
|
*/
|
|
if (rq->nr_running == 1 && p_rq->nr_running == 1) {
|
|
yielded = -ESRCH;
|
|
goto out_irq;
|
|
}
|
|
|
|
double_rq_lock(rq, p_rq);
|
|
if (task_rq(p) != p_rq) {
|
|
double_rq_unlock(rq, p_rq);
|
|
goto again;
|
|
}
|
|
|
|
if (!curr->sched_class->yield_to_task)
|
|
goto out_unlock;
|
|
|
|
if (curr->sched_class != p->sched_class)
|
|
goto out_unlock;
|
|
|
|
if (task_running(p_rq, p) || p->state)
|
|
goto out_unlock;
|
|
|
|
yielded = curr->sched_class->yield_to_task(rq, p);
|
|
if (yielded) {
|
|
schedstat_inc(rq->yld_count);
|
|
/*
|
|
* Make p's CPU reschedule; pick_next_entity takes care of
|
|
* fairness.
|
|
*/
|
|
if (preempt && rq != p_rq)
|
|
resched_curr(p_rq);
|
|
}
|
|
|
|
out_unlock:
|
|
double_rq_unlock(rq, p_rq);
|
|
out_irq:
|
|
local_irq_restore(flags);
|
|
|
|
if (yielded > 0)
|
|
schedule();
|
|
|
|
return yielded;
|
|
}
|
|
EXPORT_SYMBOL_GPL(yield_to);
|
|
|
|
int io_schedule_prepare(void)
|
|
{
|
|
int old_iowait = current->in_iowait;
|
|
|
|
current->in_iowait = 1;
|
|
blk_schedule_flush_plug(current);
|
|
|
|
return old_iowait;
|
|
}
|
|
|
|
void io_schedule_finish(int token)
|
|
{
|
|
current->in_iowait = token;
|
|
}
|
|
|
|
/*
|
|
* This task is about to go to sleep on IO. Increment rq->nr_iowait so
|
|
* that process accounting knows that this is a task in IO wait state.
|
|
*/
|
|
long __sched io_schedule_timeout(long timeout)
|
|
{
|
|
int token;
|
|
long ret;
|
|
|
|
token = io_schedule_prepare();
|
|
ret = schedule_timeout(timeout);
|
|
io_schedule_finish(token);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(io_schedule_timeout);
|
|
|
|
void __sched io_schedule(void)
|
|
{
|
|
int token;
|
|
|
|
token = io_schedule_prepare();
|
|
schedule();
|
|
io_schedule_finish(token);
|
|
}
|
|
EXPORT_SYMBOL(io_schedule);
|
|
|
|
/**
|
|
* sys_sched_get_priority_max - return maximum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* Return: On success, this syscall returns the maximum
|
|
* rt_priority that can be used by a given scheduling class.
|
|
* On failure, a negative error code is returned.
|
|
*/
|
|
SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
switch (policy) {
|
|
case SCHED_FIFO:
|
|
case SCHED_RR:
|
|
ret = MAX_USER_RT_PRIO-1;
|
|
break;
|
|
case SCHED_DEADLINE:
|
|
case SCHED_NORMAL:
|
|
case SCHED_BATCH:
|
|
case SCHED_IDLE:
|
|
ret = 0;
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_get_priority_min - return minimum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* Return: On success, this syscall returns the minimum
|
|
* rt_priority that can be used by a given scheduling class.
|
|
* On failure, a negative error code is returned.
|
|
*/
|
|
SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
switch (policy) {
|
|
case SCHED_FIFO:
|
|
case SCHED_RR:
|
|
ret = 1;
|
|
break;
|
|
case SCHED_DEADLINE:
|
|
case SCHED_NORMAL:
|
|
case SCHED_BATCH:
|
|
case SCHED_IDLE:
|
|
ret = 0;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
|
|
{
|
|
struct task_struct *p;
|
|
unsigned int time_slice;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
int retval;
|
|
|
|
if (pid < 0)
|
|
return -EINVAL;
|
|
|
|
retval = -ESRCH;
|
|
rcu_read_lock();
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
time_slice = 0;
|
|
if (p->sched_class->get_rr_interval)
|
|
time_slice = p->sched_class->get_rr_interval(rq, p);
|
|
task_rq_unlock(rq, p, &rf);
|
|
|
|
rcu_read_unlock();
|
|
jiffies_to_timespec64(time_slice, t);
|
|
return 0;
|
|
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_rr_get_interval - return the default timeslice of a process.
|
|
* @pid: pid of the process.
|
|
* @interval: userspace pointer to the timeslice value.
|
|
*
|
|
* this syscall writes the default timeslice value of a given process
|
|
* into the user-space timespec buffer. A value of '0' means infinity.
|
|
*
|
|
* Return: On success, 0 and the timeslice is in @interval. Otherwise,
|
|
* an error code.
|
|
*/
|
|
SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
|
|
struct __kernel_timespec __user *, interval)
|
|
{
|
|
struct timespec64 t;
|
|
int retval = sched_rr_get_interval(pid, &t);
|
|
|
|
if (retval == 0)
|
|
retval = put_timespec64(&t, interval);
|
|
|
|
return retval;
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT_32BIT_TIME
|
|
SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid,
|
|
struct old_timespec32 __user *, interval)
|
|
{
|
|
struct timespec64 t;
|
|
int retval = sched_rr_get_interval(pid, &t);
|
|
|
|
if (retval == 0)
|
|
retval = put_old_timespec32(&t, interval);
|
|
return retval;
|
|
}
|
|
#endif
|
|
|
|
void sched_show_task(struct task_struct *p)
|
|
{
|
|
unsigned long free = 0;
|
|
int ppid;
|
|
|
|
if (!try_get_task_stack(p))
|
|
return;
|
|
|
|
pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p));
|
|
|
|
if (p->state == TASK_RUNNING)
|
|
pr_cont(" running task ");
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
free = stack_not_used(p);
|
|
#endif
|
|
ppid = 0;
|
|
rcu_read_lock();
|
|
if (pid_alive(p))
|
|
ppid = task_pid_nr(rcu_dereference(p->real_parent));
|
|
rcu_read_unlock();
|
|
pr_cont(" stack:%5lu pid:%5d ppid:%6d flags:0x%08lx\n",
|
|
free, task_pid_nr(p), ppid,
|
|
(unsigned long)task_thread_info(p)->flags);
|
|
|
|
print_worker_info(KERN_INFO, p);
|
|
show_stack(p, NULL, KERN_INFO);
|
|
put_task_stack(p);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_show_task);
|
|
|
|
static inline bool
|
|
state_filter_match(unsigned long state_filter, struct task_struct *p)
|
|
{
|
|
/* no filter, everything matches */
|
|
if (!state_filter)
|
|
return true;
|
|
|
|
/* filter, but doesn't match */
|
|
if (!(p->state & state_filter))
|
|
return false;
|
|
|
|
/*
|
|
* When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
|
|
* TASK_KILLABLE).
|
|
*/
|
|
if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
void show_state_filter(unsigned long state_filter)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
rcu_read_lock();
|
|
for_each_process_thread(g, p) {
|
|
/*
|
|
* reset the NMI-timeout, listing all files on a slow
|
|
* console might take a lot of time:
|
|
* Also, reset softlockup watchdogs on all CPUs, because
|
|
* another CPU might be blocked waiting for us to process
|
|
* an IPI.
|
|
*/
|
|
touch_nmi_watchdog();
|
|
touch_all_softlockup_watchdogs();
|
|
if (state_filter_match(state_filter, p))
|
|
sched_show_task(p);
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
if (!state_filter)
|
|
sysrq_sched_debug_show();
|
|
#endif
|
|
rcu_read_unlock();
|
|
/*
|
|
* Only show locks if all tasks are dumped:
|
|
*/
|
|
if (!state_filter)
|
|
debug_show_all_locks();
|
|
}
|
|
|
|
/**
|
|
* init_idle - set up an idle thread for a given CPU
|
|
* @idle: task in question
|
|
* @cpu: CPU the idle task belongs to
|
|
*
|
|
* NOTE: this function does not set the idle thread's NEED_RESCHED
|
|
* flag, to make booting more robust.
|
|
*/
|
|
void init_idle(struct task_struct *idle, int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long flags;
|
|
|
|
__sched_fork(0, idle);
|
|
|
|
raw_spin_lock_irqsave(&idle->pi_lock, flags);
|
|
raw_spin_lock(&rq->lock);
|
|
|
|
idle->state = TASK_RUNNING;
|
|
idle->se.exec_start = sched_clock();
|
|
idle->flags |= PF_IDLE;
|
|
|
|
scs_task_reset(idle);
|
|
kasan_unpoison_task_stack(idle);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* Its possible that init_idle() gets called multiple times on a task,
|
|
* in that case do_set_cpus_allowed() will not do the right thing.
|
|
*
|
|
* And since this is boot we can forgo the serialization.
|
|
*/
|
|
set_cpus_allowed_common(idle, cpumask_of(cpu));
|
|
#endif
|
|
/*
|
|
* We're having a chicken and egg problem, even though we are
|
|
* holding rq->lock, the CPU isn't yet set to this CPU so the
|
|
* lockdep check in task_group() will fail.
|
|
*
|
|
* Similar case to sched_fork(). / Alternatively we could
|
|
* use task_rq_lock() here and obtain the other rq->lock.
|
|
*
|
|
* Silence PROVE_RCU
|
|
*/
|
|
rcu_read_lock();
|
|
__set_task_cpu(idle, cpu);
|
|
rcu_read_unlock();
|
|
|
|
rq->idle = idle;
|
|
rcu_assign_pointer(rq->curr, idle);
|
|
idle->on_rq = TASK_ON_RQ_QUEUED;
|
|
#ifdef CONFIG_SMP
|
|
idle->on_cpu = 1;
|
|
#endif
|
|
raw_spin_unlock(&rq->lock);
|
|
raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
|
|
|
|
/* Set the preempt count _outside_ the spinlocks! */
|
|
init_idle_preempt_count(idle, cpu);
|
|
|
|
/*
|
|
* The idle tasks have their own, simple scheduling class:
|
|
*/
|
|
idle->sched_class = &idle_sched_class;
|
|
ftrace_graph_init_idle_task(idle, cpu);
|
|
vtime_init_idle(idle, cpu);
|
|
#ifdef CONFIG_SMP
|
|
sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
int cpuset_cpumask_can_shrink(const struct cpumask *cur,
|
|
const struct cpumask *trial)
|
|
{
|
|
int ret = 1;
|
|
|
|
if (!cpumask_weight(cur))
|
|
return ret;
|
|
|
|
ret = dl_cpuset_cpumask_can_shrink(cur, trial);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int task_can_attach(struct task_struct *p,
|
|
const struct cpumask *cs_cpus_allowed)
|
|
{
|
|
int ret = 0;
|
|
|
|
/*
|
|
* Kthreads which disallow setaffinity shouldn't be moved
|
|
* to a new cpuset; we don't want to change their CPU
|
|
* affinity and isolating such threads by their set of
|
|
* allowed nodes is unnecessary. Thus, cpusets are not
|
|
* applicable for such threads. This prevents checking for
|
|
* success of set_cpus_allowed_ptr() on all attached tasks
|
|
* before cpus_mask may be changed.
|
|
*/
|
|
if (p->flags & PF_NO_SETAFFINITY) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
|
|
cs_cpus_allowed))
|
|
ret = dl_task_can_attach(p, cs_cpus_allowed);
|
|
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
bool sched_smp_initialized __read_mostly;
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/* Migrate current task p to target_cpu */
|
|
int migrate_task_to(struct task_struct *p, int target_cpu)
|
|
{
|
|
struct migration_arg arg = { p, target_cpu };
|
|
int curr_cpu = task_cpu(p);
|
|
|
|
if (curr_cpu == target_cpu)
|
|
return 0;
|
|
|
|
if (!cpumask_test_cpu(target_cpu, p->cpus_ptr))
|
|
return -EINVAL;
|
|
|
|
/* TODO: This is not properly updating schedstats */
|
|
|
|
trace_sched_move_numa(p, curr_cpu, target_cpu);
|
|
return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
|
|
}
|
|
|
|
/*
|
|
* Requeue a task on a given node and accurately track the number of NUMA
|
|
* tasks on the runqueues
|
|
*/
|
|
void sched_setnuma(struct task_struct *p, int nid)
|
|
{
|
|
bool queued, running;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(p, &rf);
|
|
queued = task_on_rq_queued(p);
|
|
running = task_current(rq, p);
|
|
|
|
if (queued)
|
|
dequeue_task(rq, p, DEQUEUE_SAVE);
|
|
if (running)
|
|
put_prev_task(rq, p);
|
|
|
|
p->numa_preferred_nid = nid;
|
|
|
|
if (queued)
|
|
enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
|
|
if (running)
|
|
set_next_task(rq, p);
|
|
task_rq_unlock(rq, p, &rf);
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/*
|
|
* Ensure that the idle task is using init_mm right before its CPU goes
|
|
* offline.
|
|
*/
|
|
void idle_task_exit(void)
|
|
{
|
|
struct mm_struct *mm = current->active_mm;
|
|
|
|
BUG_ON(cpu_online(smp_processor_id()));
|
|
BUG_ON(current != this_rq()->idle);
|
|
|
|
if (mm != &init_mm) {
|
|
switch_mm(mm, &init_mm, current);
|
|
finish_arch_post_lock_switch();
|
|
}
|
|
|
|
/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
|
|
}
|
|
|
|
/*
|
|
* Since this CPU is going 'away' for a while, fold any nr_active delta
|
|
* we might have. Assumes we're called after migrate_tasks() so that the
|
|
* nr_active count is stable. We need to take the teardown thread which
|
|
* is calling this into account, so we hand in adjust = 1 to the load
|
|
* calculation.
|
|
*
|
|
* Also see the comment "Global load-average calculations".
|
|
*/
|
|
static void calc_load_migrate(struct rq *rq)
|
|
{
|
|
long delta = calc_load_fold_active(rq, 1);
|
|
if (delta)
|
|
atomic_long_add(delta, &calc_load_tasks);
|
|
}
|
|
|
|
static struct task_struct *__pick_migrate_task(struct rq *rq)
|
|
{
|
|
const struct sched_class *class;
|
|
struct task_struct *next;
|
|
|
|
for_each_class(class) {
|
|
next = class->pick_next_task(rq);
|
|
if (next) {
|
|
next->sched_class->put_prev_task(rq, next);
|
|
return next;
|
|
}
|
|
}
|
|
|
|
/* The idle class should always have a runnable task */
|
|
BUG();
|
|
}
|
|
|
|
/*
|
|
* Migrate all tasks from the rq, sleeping tasks will be migrated by
|
|
* try_to_wake_up()->select_task_rq().
|
|
*
|
|
* Called with rq->lock held even though we'er in stop_machine() and
|
|
* there's no concurrency possible, we hold the required locks anyway
|
|
* because of lock validation efforts.
|
|
*/
|
|
static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf)
|
|
{
|
|
struct rq *rq = dead_rq;
|
|
struct task_struct *next, *stop = rq->stop;
|
|
struct rq_flags orf = *rf;
|
|
int dest_cpu;
|
|
|
|
/*
|
|
* Fudge the rq selection such that the below task selection loop
|
|
* doesn't get stuck on the currently eligible stop task.
|
|
*
|
|
* We're currently inside stop_machine() and the rq is either stuck
|
|
* in the stop_machine_cpu_stop() loop, or we're executing this code,
|
|
* either way we should never end up calling schedule() until we're
|
|
* done here.
|
|
*/
|
|
rq->stop = NULL;
|
|
|
|
/*
|
|
* put_prev_task() and pick_next_task() sched
|
|
* class method both need to have an up-to-date
|
|
* value of rq->clock[_task]
|
|
*/
|
|
update_rq_clock(rq);
|
|
|
|
for (;;) {
|
|
/*
|
|
* There's this thread running, bail when that's the only
|
|
* remaining thread:
|
|
*/
|
|
if (rq->nr_running == 1)
|
|
break;
|
|
|
|
next = __pick_migrate_task(rq);
|
|
|
|
/*
|
|
* Rules for changing task_struct::cpus_mask are holding
|
|
* both pi_lock and rq->lock, such that holding either
|
|
* stabilizes the mask.
|
|
*
|
|
* Drop rq->lock is not quite as disastrous as it usually is
|
|
* because !cpu_active at this point, which means load-balance
|
|
* will not interfere. Also, stop-machine.
|
|
*/
|
|
rq_unlock(rq, rf);
|
|
raw_spin_lock(&next->pi_lock);
|
|
rq_relock(rq, rf);
|
|
|
|
/*
|
|
* Since we're inside stop-machine, _nothing_ should have
|
|
* changed the task, WARN if weird stuff happened, because in
|
|
* that case the above rq->lock drop is a fail too.
|
|
*/
|
|
if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
|
|
raw_spin_unlock(&next->pi_lock);
|
|
continue;
|
|
}
|
|
|
|
/* Find suitable destination for @next, with force if needed. */
|
|
dest_cpu = select_fallback_rq(dead_rq->cpu, next);
|
|
rq = __migrate_task(rq, rf, next, dest_cpu);
|
|
if (rq != dead_rq) {
|
|
rq_unlock(rq, rf);
|
|
rq = dead_rq;
|
|
*rf = orf;
|
|
rq_relock(rq, rf);
|
|
}
|
|
raw_spin_unlock(&next->pi_lock);
|
|
}
|
|
|
|
rq->stop = stop;
|
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
void set_rq_online(struct rq *rq)
|
|
{
|
|
if (!rq->online) {
|
|
const struct sched_class *class;
|
|
|
|
cpumask_set_cpu(rq->cpu, rq->rd->online);
|
|
rq->online = 1;
|
|
|
|
for_each_class(class) {
|
|
if (class->rq_online)
|
|
class->rq_online(rq);
|
|
}
|
|
}
|
|
}
|
|
|
|
void set_rq_offline(struct rq *rq)
|
|
{
|
|
if (rq->online) {
|
|
const struct sched_class *class;
|
|
|
|
for_each_class(class) {
|
|
if (class->rq_offline)
|
|
class->rq_offline(rq);
|
|
}
|
|
|
|
cpumask_clear_cpu(rq->cpu, rq->rd->online);
|
|
rq->online = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* used to mark begin/end of suspend/resume:
|
|
*/
|
|
static int num_cpus_frozen;
|
|
|
|
/*
|
|
* Update cpusets according to cpu_active mask. If cpusets are
|
|
* disabled, cpuset_update_active_cpus() becomes a simple wrapper
|
|
* around partition_sched_domains().
|
|
*
|
|
* If we come here as part of a suspend/resume, don't touch cpusets because we
|
|
* want to restore it back to its original state upon resume anyway.
|
|
*/
|
|
static void cpuset_cpu_active(void)
|
|
{
|
|
if (cpuhp_tasks_frozen) {
|
|
/*
|
|
* num_cpus_frozen tracks how many CPUs are involved in suspend
|
|
* resume sequence. As long as this is not the last online
|
|
* operation in the resume sequence, just build a single sched
|
|
* domain, ignoring cpusets.
|
|
*/
|
|
partition_sched_domains(1, NULL, NULL);
|
|
if (--num_cpus_frozen)
|
|
return;
|
|
/*
|
|
* This is the last CPU online operation. So fall through and
|
|
* restore the original sched domains by considering the
|
|
* cpuset configurations.
|
|
*/
|
|
cpuset_force_rebuild();
|
|
}
|
|
cpuset_update_active_cpus();
|
|
}
|
|
|
|
static int cpuset_cpu_inactive(unsigned int cpu)
|
|
{
|
|
if (!cpuhp_tasks_frozen) {
|
|
if (dl_cpu_busy(cpu))
|
|
return -EBUSY;
|
|
cpuset_update_active_cpus();
|
|
} else {
|
|
num_cpus_frozen++;
|
|
partition_sched_domains(1, NULL, NULL);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int sched_cpu_activate(unsigned int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct rq_flags rf;
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
/*
|
|
* When going up, increment the number of cores with SMT present.
|
|
*/
|
|
if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
|
|
static_branch_inc_cpuslocked(&sched_smt_present);
|
|
#endif
|
|
set_cpu_active(cpu, true);
|
|
|
|
if (sched_smp_initialized) {
|
|
sched_domains_numa_masks_set(cpu);
|
|
cpuset_cpu_active();
|
|
}
|
|
|
|
/*
|
|
* Put the rq online, if not already. This happens:
|
|
*
|
|
* 1) In the early boot process, because we build the real domains
|
|
* after all CPUs have been brought up.
|
|
*
|
|
* 2) At runtime, if cpuset_cpu_active() fails to rebuild the
|
|
* domains.
|
|
*/
|
|
rq_lock_irqsave(rq, &rf);
|
|
if (rq->rd) {
|
|
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
|
|
set_rq_online(rq);
|
|
}
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int sched_cpu_deactivate(unsigned int cpu)
|
|
{
|
|
int ret;
|
|
|
|
set_cpu_active(cpu, false);
|
|
/*
|
|
* We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
|
|
* users of this state to go away such that all new such users will
|
|
* observe it.
|
|
*
|
|
* Do sync before park smpboot threads to take care the rcu boost case.
|
|
*/
|
|
synchronize_rcu();
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
/*
|
|
* When going down, decrement the number of cores with SMT present.
|
|
*/
|
|
if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
|
|
static_branch_dec_cpuslocked(&sched_smt_present);
|
|
#endif
|
|
|
|
if (!sched_smp_initialized)
|
|
return 0;
|
|
|
|
ret = cpuset_cpu_inactive(cpu);
|
|
if (ret) {
|
|
set_cpu_active(cpu, true);
|
|
return ret;
|
|
}
|
|
sched_domains_numa_masks_clear(cpu);
|
|
return 0;
|
|
}
|
|
|
|
static void sched_rq_cpu_starting(unsigned int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
rq->calc_load_update = calc_load_update;
|
|
update_max_interval();
|
|
}
|
|
|
|
int sched_cpu_starting(unsigned int cpu)
|
|
{
|
|
sched_rq_cpu_starting(cpu);
|
|
sched_tick_start(cpu);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
int sched_cpu_dying(unsigned int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct rq_flags rf;
|
|
|
|
/* Handle pending wakeups and then migrate everything off */
|
|
sched_tick_stop(cpu);
|
|
|
|
rq_lock_irqsave(rq, &rf);
|
|
if (rq->rd) {
|
|
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
|
|
set_rq_offline(rq);
|
|
}
|
|
migrate_tasks(rq, &rf);
|
|
BUG_ON(rq->nr_running != 1);
|
|
rq_unlock_irqrestore(rq, &rf);
|
|
|
|
calc_load_migrate(rq);
|
|
update_max_interval();
|
|
nohz_balance_exit_idle(rq);
|
|
hrtick_clear(rq);
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
void __init sched_init_smp(void)
|
|
{
|
|
sched_init_numa();
|
|
|
|
/*
|
|
* There's no userspace yet to cause hotplug operations; hence all the
|
|
* CPU masks are stable and all blatant races in the below code cannot
|
|
* happen.
|
|
*/
|
|
mutex_lock(&sched_domains_mutex);
|
|
sched_init_domains(cpu_active_mask);
|
|
mutex_unlock(&sched_domains_mutex);
|
|
|
|
/* Move init over to a non-isolated CPU */
|
|
if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
|
|
BUG();
|
|
sched_init_granularity();
|
|
|
|
init_sched_rt_class();
|
|
init_sched_dl_class();
|
|
|
|
sched_smp_initialized = true;
|
|
}
|
|
|
|
static int __init migration_init(void)
|
|
{
|
|
sched_cpu_starting(smp_processor_id());
|
|
return 0;
|
|
}
|
|
early_initcall(migration_init);
|
|
|
|
#else
|
|
void __init sched_init_smp(void)
|
|
{
|
|
sched_init_granularity();
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
int in_sched_functions(unsigned long addr)
|
|
{
|
|
return in_lock_functions(addr) ||
|
|
(addr >= (unsigned long)__sched_text_start
|
|
&& addr < (unsigned long)__sched_text_end);
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_SCHED
|
|
/*
|
|
* Default task group.
|
|
* Every task in system belongs to this group at bootup.
|
|
*/
|
|
struct task_group root_task_group;
|
|
LIST_HEAD(task_groups);
|
|
|
|
/* Cacheline aligned slab cache for task_group */
|
|
static struct kmem_cache *task_group_cache __read_mostly;
|
|
#endif
|
|
|
|
DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
|
|
DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
|
|
|
|
void __init sched_init(void)
|
|
{
|
|
unsigned long ptr = 0;
|
|
int i;
|
|
|
|
/* Make sure the linker didn't screw up */
|
|
BUG_ON(&idle_sched_class + 1 != &fair_sched_class ||
|
|
&fair_sched_class + 1 != &rt_sched_class ||
|
|
&rt_sched_class + 1 != &dl_sched_class);
|
|
#ifdef CONFIG_SMP
|
|
BUG_ON(&dl_sched_class + 1 != &stop_sched_class);
|
|
#endif
|
|
|
|
wait_bit_init();
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
ptr += 2 * nr_cpu_ids * sizeof(void **);
|
|
#endif
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
ptr += 2 * nr_cpu_ids * sizeof(void **);
|
|
#endif
|
|
if (ptr) {
|
|
ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT);
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
root_task_group.se = (struct sched_entity **)ptr;
|
|
ptr += nr_cpu_ids * sizeof(void **);
|
|
|
|
root_task_group.cfs_rq = (struct cfs_rq **)ptr;
|
|
ptr += nr_cpu_ids * sizeof(void **);
|
|
|
|
root_task_group.shares = ROOT_TASK_GROUP_LOAD;
|
|
init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
root_task_group.rt_se = (struct sched_rt_entity **)ptr;
|
|
ptr += nr_cpu_ids * sizeof(void **);
|
|
|
|
root_task_group.rt_rq = (struct rt_rq **)ptr;
|
|
ptr += nr_cpu_ids * sizeof(void **);
|
|
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
}
|
|
#ifdef CONFIG_CPUMASK_OFFSTACK
|
|
for_each_possible_cpu(i) {
|
|
per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
|
|
cpumask_size(), GFP_KERNEL, cpu_to_node(i));
|
|
per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
|
|
cpumask_size(), GFP_KERNEL, cpu_to_node(i));
|
|
}
|
|
#endif /* CONFIG_CPUMASK_OFFSTACK */
|
|
|
|
init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
|
|
init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
|
|
|
|
#ifdef CONFIG_SMP
|
|
init_defrootdomain();
|
|
#endif
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
init_rt_bandwidth(&root_task_group.rt_bandwidth,
|
|
global_rt_period(), global_rt_runtime());
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
#ifdef CONFIG_CGROUP_SCHED
|
|
task_group_cache = KMEM_CACHE(task_group, 0);
|
|
|
|
list_add(&root_task_group.list, &task_groups);
|
|
INIT_LIST_HEAD(&root_task_group.children);
|
|
INIT_LIST_HEAD(&root_task_group.siblings);
|
|
autogroup_init(&init_task);
|
|
#endif /* CONFIG_CGROUP_SCHED */
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct rq *rq;
|
|
|
|
rq = cpu_rq(i);
|
|
raw_spin_lock_init(&rq->lock);
|
|
rq->nr_running = 0;
|
|
rq->calc_load_active = 0;
|
|
rq->calc_load_update = jiffies + LOAD_FREQ;
|
|
init_cfs_rq(&rq->cfs);
|
|
init_rt_rq(&rq->rt);
|
|
init_dl_rq(&rq->dl);
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
|
|
rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
|
|
/*
|
|
* How much CPU bandwidth does root_task_group get?
|
|
*
|
|
* In case of task-groups formed thr' the cgroup filesystem, it
|
|
* gets 100% of the CPU resources in the system. This overall
|
|
* system CPU resource is divided among the tasks of
|
|
* root_task_group and its child task-groups in a fair manner,
|
|
* based on each entity's (task or task-group's) weight
|
|
* (se->load.weight).
|
|
*
|
|
* In other words, if root_task_group has 10 tasks of weight
|
|
* 1024) and two child groups A0 and A1 (of weight 1024 each),
|
|
* then A0's share of the CPU resource is:
|
|
*
|
|
* A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
|
|
*
|
|
* We achieve this by letting root_task_group's tasks sit
|
|
* directly in rq->cfs (i.e root_task_group->se[] = NULL).
|
|
*/
|
|
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
|
|
#endif
|
|
#ifdef CONFIG_SMP
|
|
rq->sd = NULL;
|
|
rq->rd = NULL;
|
|
rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
|
|
rq->balance_callback = NULL;
|
|
rq->active_balance = 0;
|
|
rq->next_balance = jiffies;
|
|
rq->push_cpu = 0;
|
|
rq->cpu = i;
|
|
rq->online = 0;
|
|
rq->idle_stamp = 0;
|
|
rq->avg_idle = 2*sysctl_sched_migration_cost;
|
|
rq->max_idle_balance_cost = sysctl_sched_migration_cost;
|
|
|
|
INIT_LIST_HEAD(&rq->cfs_tasks);
|
|
|
|
rq_attach_root(rq, &def_root_domain);
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
rq->last_blocked_load_update_tick = jiffies;
|
|
atomic_set(&rq->nohz_flags, 0);
|
|
|
|
rq_csd_init(rq, &rq->nohz_csd, nohz_csd_func);
|
|
#endif
|
|
#endif /* CONFIG_SMP */
|
|
hrtick_rq_init(rq);
|
|
atomic_set(&rq->nr_iowait, 0);
|
|
}
|
|
|
|
set_load_weight(&init_task, false);
|
|
|
|
/*
|
|
* The boot idle thread does lazy MMU switching as well:
|
|
*/
|
|
mmgrab(&init_mm);
|
|
enter_lazy_tlb(&init_mm, current);
|
|
|
|
/*
|
|
* Make us the idle thread. Technically, schedule() should not be
|
|
* called from this thread, however somewhere below it might be,
|
|
* but because we are the idle thread, we just pick up running again
|
|
* when this runqueue becomes "idle".
|
|
*/
|
|
init_idle(current, smp_processor_id());
|
|
|
|
calc_load_update = jiffies + LOAD_FREQ;
|
|
|
|
#ifdef CONFIG_SMP
|
|
idle_thread_set_boot_cpu();
|
|
#endif
|
|
init_sched_fair_class();
|
|
|
|
init_schedstats();
|
|
|
|
psi_init();
|
|
|
|
init_uclamp();
|
|
|
|
scheduler_running = 1;
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
|
|
static inline int preempt_count_equals(int preempt_offset)
|
|
{
|
|
int nested = preempt_count() + rcu_preempt_depth();
|
|
|
|
return (nested == preempt_offset);
|
|
}
|
|
|
|
void __might_sleep(const char *file, int line, int preempt_offset)
|
|
{
|
|
/*
|
|
* Blocking primitives will set (and therefore destroy) current->state,
|
|
* since we will exit with TASK_RUNNING make sure we enter with it,
|
|
* otherwise we will destroy state.
|
|
*/
|
|
WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
|
|
"do not call blocking ops when !TASK_RUNNING; "
|
|
"state=%lx set at [<%p>] %pS\n",
|
|
current->state,
|
|
(void *)current->task_state_change,
|
|
(void *)current->task_state_change);
|
|
|
|
___might_sleep(file, line, preempt_offset);
|
|
}
|
|
EXPORT_SYMBOL(__might_sleep);
|
|
|
|
void ___might_sleep(const char *file, int line, int preempt_offset)
|
|
{
|
|
/* Ratelimiting timestamp: */
|
|
static unsigned long prev_jiffy;
|
|
|
|
unsigned long preempt_disable_ip;
|
|
|
|
/* WARN_ON_ONCE() by default, no rate limit required: */
|
|
rcu_sleep_check();
|
|
|
|
if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
|
|
!is_idle_task(current) && !current->non_block_count) ||
|
|
system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
|
|
oops_in_progress)
|
|
return;
|
|
|
|
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
|
|
return;
|
|
prev_jiffy = jiffies;
|
|
|
|
/* Save this before calling printk(), since that will clobber it: */
|
|
preempt_disable_ip = get_preempt_disable_ip(current);
|
|
|
|
printk(KERN_ERR
|
|
"BUG: sleeping function called from invalid context at %s:%d\n",
|
|
file, line);
|
|
printk(KERN_ERR
|
|
"in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n",
|
|
in_atomic(), irqs_disabled(), current->non_block_count,
|
|
current->pid, current->comm);
|
|
|
|
if (task_stack_end_corrupted(current))
|
|
printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
|
|
|
|
debug_show_held_locks(current);
|
|
if (irqs_disabled())
|
|
print_irqtrace_events(current);
|
|
if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
|
|
&& !preempt_count_equals(preempt_offset)) {
|
|
pr_err("Preemption disabled at:");
|
|
print_ip_sym(KERN_ERR, preempt_disable_ip);
|
|
}
|
|
dump_stack();
|
|
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
|
|
}
|
|
EXPORT_SYMBOL(___might_sleep);
|
|
|
|
void __cant_sleep(const char *file, int line, int preempt_offset)
|
|
{
|
|
static unsigned long prev_jiffy;
|
|
|
|
if (irqs_disabled())
|
|
return;
|
|
|
|
if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
|
|
return;
|
|
|
|
if (preempt_count() > preempt_offset)
|
|
return;
|
|
|
|
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
|
|
return;
|
|
prev_jiffy = jiffies;
|
|
|
|
printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
|
|
printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
|
|
in_atomic(), irqs_disabled(),
|
|
current->pid, current->comm);
|
|
|
|
debug_show_held_locks(current);
|
|
dump_stack();
|
|
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__cant_sleep);
|
|
#endif
|
|
|
|
#ifdef CONFIG_MAGIC_SYSRQ
|
|
void normalize_rt_tasks(void)
|
|
{
|
|
struct task_struct *g, *p;
|
|
struct sched_attr attr = {
|
|
.sched_policy = SCHED_NORMAL,
|
|
};
|
|
|
|
read_lock(&tasklist_lock);
|
|
for_each_process_thread(g, p) {
|
|
/*
|
|
* Only normalize user tasks:
|
|
*/
|
|
if (p->flags & PF_KTHREAD)
|
|
continue;
|
|
|
|
p->se.exec_start = 0;
|
|
schedstat_set(p->se.statistics.wait_start, 0);
|
|
schedstat_set(p->se.statistics.sleep_start, 0);
|
|
schedstat_set(p->se.statistics.block_start, 0);
|
|
|
|
if (!dl_task(p) && !rt_task(p)) {
|
|
/*
|
|
* Renice negative nice level userspace
|
|
* tasks back to 0:
|
|
*/
|
|
if (task_nice(p) < 0)
|
|
set_user_nice(p, 0);
|
|
continue;
|
|
}
|
|
|
|
__sched_setscheduler(p, &attr, false, false);
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
#endif /* CONFIG_MAGIC_SYSRQ */
|
|
|
|
#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
|
|
/*
|
|
* These functions are only useful for the IA64 MCA handling, or kdb.
|
|
*
|
|
* They can only be called when the whole system has been
|
|
* stopped - every CPU needs to be quiescent, and no scheduling
|
|
* activity can take place. Using them for anything else would
|
|
* be a serious bug, and as a result, they aren't even visible
|
|
* under any other configuration.
|
|
*/
|
|
|
|
/**
|
|
* curr_task - return the current task for a given CPU.
|
|
* @cpu: the processor in question.
|
|
*
|
|
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
|
|
*
|
|
* Return: The current task for @cpu.
|
|
*/
|
|
struct task_struct *curr_task(int cpu)
|
|
{
|
|
return cpu_curr(cpu);
|
|
}
|
|
|
|
#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
|
|
|
|
#ifdef CONFIG_IA64
|
|
/**
|
|
* ia64_set_curr_task - set the current task for a given CPU.
|
|
* @cpu: the processor in question.
|
|
* @p: the task pointer to set.
|
|
*
|
|
* Description: This function must only be used when non-maskable interrupts
|
|
* are serviced on a separate stack. It allows the architecture to switch the
|
|
* notion of the current task on a CPU in a non-blocking manner. This function
|
|
* must be called with all CPU's synchronized, and interrupts disabled, the
|
|
* and caller must save the original value of the current task (see
|
|
* curr_task() above) and restore that value before reenabling interrupts and
|
|
* re-starting the system.
|
|
*
|
|
* ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
|
|
*/
|
|
void ia64_set_curr_task(int cpu, struct task_struct *p)
|
|
{
|
|
cpu_curr(cpu) = p;
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef CONFIG_CGROUP_SCHED
|
|
/* task_group_lock serializes the addition/removal of task groups */
|
|
static DEFINE_SPINLOCK(task_group_lock);
|
|
|
|
static inline void alloc_uclamp_sched_group(struct task_group *tg,
|
|
struct task_group *parent)
|
|
{
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
enum uclamp_id clamp_id;
|
|
|
|
for_each_clamp_id(clamp_id) {
|
|
uclamp_se_set(&tg->uclamp_req[clamp_id],
|
|
uclamp_none(clamp_id), false);
|
|
tg->uclamp[clamp_id] = parent->uclamp[clamp_id];
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void sched_free_group(struct task_group *tg)
|
|
{
|
|
free_fair_sched_group(tg);
|
|
free_rt_sched_group(tg);
|
|
autogroup_free(tg);
|
|
kmem_cache_free(task_group_cache, tg);
|
|
}
|
|
|
|
/* allocate runqueue etc for a new task group */
|
|
struct task_group *sched_create_group(struct task_group *parent)
|
|
{
|
|
struct task_group *tg;
|
|
|
|
tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
|
|
if (!tg)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
if (!alloc_fair_sched_group(tg, parent))
|
|
goto err;
|
|
|
|
if (!alloc_rt_sched_group(tg, parent))
|
|
goto err;
|
|
|
|
alloc_uclamp_sched_group(tg, parent);
|
|
|
|
return tg;
|
|
|
|
err:
|
|
sched_free_group(tg);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
|
|
void sched_online_group(struct task_group *tg, struct task_group *parent)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&task_group_lock, flags);
|
|
list_add_rcu(&tg->list, &task_groups);
|
|
|
|
/* Root should already exist: */
|
|
WARN_ON(!parent);
|
|
|
|
tg->parent = parent;
|
|
INIT_LIST_HEAD(&tg->children);
|
|
list_add_rcu(&tg->siblings, &parent->children);
|
|
spin_unlock_irqrestore(&task_group_lock, flags);
|
|
|
|
online_fair_sched_group(tg);
|
|
}
|
|
|
|
/* rcu callback to free various structures associated with a task group */
|
|
static void sched_free_group_rcu(struct rcu_head *rhp)
|
|
{
|
|
/* Now it should be safe to free those cfs_rqs: */
|
|
sched_free_group(container_of(rhp, struct task_group, rcu));
|
|
}
|
|
|
|
void sched_destroy_group(struct task_group *tg)
|
|
{
|
|
/* Wait for possible concurrent references to cfs_rqs complete: */
|
|
call_rcu(&tg->rcu, sched_free_group_rcu);
|
|
}
|
|
|
|
void sched_offline_group(struct task_group *tg)
|
|
{
|
|
unsigned long flags;
|
|
|
|
/* End participation in shares distribution: */
|
|
unregister_fair_sched_group(tg);
|
|
|
|
spin_lock_irqsave(&task_group_lock, flags);
|
|
list_del_rcu(&tg->list);
|
|
list_del_rcu(&tg->siblings);
|
|
spin_unlock_irqrestore(&task_group_lock, flags);
|
|
}
|
|
|
|
static void sched_change_group(struct task_struct *tsk, int type)
|
|
{
|
|
struct task_group *tg;
|
|
|
|
/*
|
|
* All callers are synchronized by task_rq_lock(); we do not use RCU
|
|
* which is pointless here. Thus, we pass "true" to task_css_check()
|
|
* to prevent lockdep warnings.
|
|
*/
|
|
tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
|
|
struct task_group, css);
|
|
tg = autogroup_task_group(tsk, tg);
|
|
tsk->sched_task_group = tg;
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
if (tsk->sched_class->task_change_group)
|
|
tsk->sched_class->task_change_group(tsk, type);
|
|
else
|
|
#endif
|
|
set_task_rq(tsk, task_cpu(tsk));
|
|
}
|
|
|
|
/*
|
|
* Change task's runqueue when it moves between groups.
|
|
*
|
|
* The caller of this function should have put the task in its new group by
|
|
* now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
|
|
* its new group.
|
|
*/
|
|
void sched_move_task(struct task_struct *tsk)
|
|
{
|
|
int queued, running, queue_flags =
|
|
DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(tsk, &rf);
|
|
update_rq_clock(rq);
|
|
|
|
running = task_current(rq, tsk);
|
|
queued = task_on_rq_queued(tsk);
|
|
|
|
if (queued)
|
|
dequeue_task(rq, tsk, queue_flags);
|
|
if (running)
|
|
put_prev_task(rq, tsk);
|
|
|
|
sched_change_group(tsk, TASK_MOVE_GROUP);
|
|
|
|
if (queued)
|
|
enqueue_task(rq, tsk, queue_flags);
|
|
if (running) {
|
|
set_next_task(rq, tsk);
|
|
/*
|
|
* After changing group, the running task may have joined a
|
|
* throttled one but it's still the running task. Trigger a
|
|
* resched to make sure that task can still run.
|
|
*/
|
|
resched_curr(rq);
|
|
}
|
|
|
|
task_rq_unlock(rq, tsk, &rf);
|
|
}
|
|
|
|
static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
|
|
{
|
|
return css ? container_of(css, struct task_group, css) : NULL;
|
|
}
|
|
|
|
static struct cgroup_subsys_state *
|
|
cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
|
|
{
|
|
struct task_group *parent = css_tg(parent_css);
|
|
struct task_group *tg;
|
|
|
|
if (!parent) {
|
|
/* This is early initialization for the top cgroup */
|
|
return &root_task_group.css;
|
|
}
|
|
|
|
tg = sched_create_group(parent);
|
|
if (IS_ERR(tg))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
return &tg->css;
|
|
}
|
|
|
|
/* Expose task group only after completing cgroup initialization */
|
|
static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
struct task_group *parent = css_tg(css->parent);
|
|
|
|
if (parent)
|
|
sched_online_group(tg, parent);
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
/* Propagate the effective uclamp value for the new group */
|
|
cpu_util_update_eff(css);
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
|
|
sched_offline_group(tg);
|
|
}
|
|
|
|
static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
|
|
/*
|
|
* Relies on the RCU grace period between css_released() and this.
|
|
*/
|
|
sched_free_group(tg);
|
|
}
|
|
|
|
/*
|
|
* This is called before wake_up_new_task(), therefore we really only
|
|
* have to set its group bits, all the other stuff does not apply.
|
|
*/
|
|
static void cpu_cgroup_fork(struct task_struct *task)
|
|
{
|
|
struct rq_flags rf;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(task, &rf);
|
|
|
|
update_rq_clock(rq);
|
|
sched_change_group(task, TASK_SET_GROUP);
|
|
|
|
task_rq_unlock(rq, task, &rf);
|
|
}
|
|
|
|
static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct cgroup_subsys_state *css;
|
|
int ret = 0;
|
|
|
|
cgroup_taskset_for_each(task, css, tset) {
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
if (!sched_rt_can_attach(css_tg(css), task))
|
|
return -EINVAL;
|
|
#endif
|
|
/*
|
|
* Serialize against wake_up_new_task() such that if its
|
|
* running, we're sure to observe its full state.
|
|
*/
|
|
raw_spin_lock_irq(&task->pi_lock);
|
|
/*
|
|
* Avoid calling sched_move_task() before wake_up_new_task()
|
|
* has happened. This would lead to problems with PELT, due to
|
|
* move wanting to detach+attach while we're not attached yet.
|
|
*/
|
|
if (task->state == TASK_NEW)
|
|
ret = -EINVAL;
|
|
raw_spin_unlock_irq(&task->pi_lock);
|
|
|
|
if (ret)
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void cpu_cgroup_attach(struct cgroup_taskset *tset)
|
|
{
|
|
struct task_struct *task;
|
|
struct cgroup_subsys_state *css;
|
|
|
|
cgroup_taskset_for_each(task, css, tset)
|
|
sched_move_task(task);
|
|
}
|
|
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
static void cpu_util_update_eff(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys_state *top_css = css;
|
|
struct uclamp_se *uc_parent = NULL;
|
|
struct uclamp_se *uc_se = NULL;
|
|
unsigned int eff[UCLAMP_CNT];
|
|
enum uclamp_id clamp_id;
|
|
unsigned int clamps;
|
|
|
|
css_for_each_descendant_pre(css, top_css) {
|
|
uc_parent = css_tg(css)->parent
|
|
? css_tg(css)->parent->uclamp : NULL;
|
|
|
|
for_each_clamp_id(clamp_id) {
|
|
/* Assume effective clamps matches requested clamps */
|
|
eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value;
|
|
/* Cap effective clamps with parent's effective clamps */
|
|
if (uc_parent &&
|
|
eff[clamp_id] > uc_parent[clamp_id].value) {
|
|
eff[clamp_id] = uc_parent[clamp_id].value;
|
|
}
|
|
}
|
|
/* Ensure protection is always capped by limit */
|
|
eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]);
|
|
|
|
/* Propagate most restrictive effective clamps */
|
|
clamps = 0x0;
|
|
uc_se = css_tg(css)->uclamp;
|
|
for_each_clamp_id(clamp_id) {
|
|
if (eff[clamp_id] == uc_se[clamp_id].value)
|
|
continue;
|
|
uc_se[clamp_id].value = eff[clamp_id];
|
|
uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]);
|
|
clamps |= (0x1 << clamp_id);
|
|
}
|
|
if (!clamps) {
|
|
css = css_rightmost_descendant(css);
|
|
continue;
|
|
}
|
|
|
|
/* Immediately update descendants RUNNABLE tasks */
|
|
uclamp_update_active_tasks(css, clamps);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Integer 10^N with a given N exponent by casting to integer the literal "1eN"
|
|
* C expression. Since there is no way to convert a macro argument (N) into a
|
|
* character constant, use two levels of macros.
|
|
*/
|
|
#define _POW10(exp) ((unsigned int)1e##exp)
|
|
#define POW10(exp) _POW10(exp)
|
|
|
|
struct uclamp_request {
|
|
#define UCLAMP_PERCENT_SHIFT 2
|
|
#define UCLAMP_PERCENT_SCALE (100 * POW10(UCLAMP_PERCENT_SHIFT))
|
|
s64 percent;
|
|
u64 util;
|
|
int ret;
|
|
};
|
|
|
|
static inline struct uclamp_request
|
|
capacity_from_percent(char *buf)
|
|
{
|
|
struct uclamp_request req = {
|
|
.percent = UCLAMP_PERCENT_SCALE,
|
|
.util = SCHED_CAPACITY_SCALE,
|
|
.ret = 0,
|
|
};
|
|
|
|
buf = strim(buf);
|
|
if (strcmp(buf, "max")) {
|
|
req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
|
|
&req.percent);
|
|
if (req.ret)
|
|
return req;
|
|
if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
|
|
req.ret = -ERANGE;
|
|
return req;
|
|
}
|
|
|
|
req.util = req.percent << SCHED_CAPACITY_SHIFT;
|
|
req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
|
|
}
|
|
|
|
return req;
|
|
}
|
|
|
|
static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off,
|
|
enum uclamp_id clamp_id)
|
|
{
|
|
struct uclamp_request req;
|
|
struct task_group *tg;
|
|
|
|
req = capacity_from_percent(buf);
|
|
if (req.ret)
|
|
return req.ret;
|
|
|
|
static_branch_enable(&sched_uclamp_used);
|
|
|
|
mutex_lock(&uclamp_mutex);
|
|
rcu_read_lock();
|
|
|
|
tg = css_tg(of_css(of));
|
|
if (tg->uclamp_req[clamp_id].value != req.util)
|
|
uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false);
|
|
|
|
/*
|
|
* Because of not recoverable conversion rounding we keep track of the
|
|
* exact requested value
|
|
*/
|
|
tg->uclamp_pct[clamp_id] = req.percent;
|
|
|
|
/* Update effective clamps to track the most restrictive value */
|
|
cpu_util_update_eff(of_css(of));
|
|
|
|
rcu_read_unlock();
|
|
mutex_unlock(&uclamp_mutex);
|
|
|
|
return nbytes;
|
|
}
|
|
|
|
static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes,
|
|
loff_t off)
|
|
{
|
|
return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN);
|
|
}
|
|
|
|
static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes,
|
|
loff_t off)
|
|
{
|
|
return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX);
|
|
}
|
|
|
|
static inline void cpu_uclamp_print(struct seq_file *sf,
|
|
enum uclamp_id clamp_id)
|
|
{
|
|
struct task_group *tg;
|
|
u64 util_clamp;
|
|
u64 percent;
|
|
u32 rem;
|
|
|
|
rcu_read_lock();
|
|
tg = css_tg(seq_css(sf));
|
|
util_clamp = tg->uclamp_req[clamp_id].value;
|
|
rcu_read_unlock();
|
|
|
|
if (util_clamp == SCHED_CAPACITY_SCALE) {
|
|
seq_puts(sf, "max\n");
|
|
return;
|
|
}
|
|
|
|
percent = tg->uclamp_pct[clamp_id];
|
|
percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem);
|
|
seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem);
|
|
}
|
|
|
|
static int cpu_uclamp_min_show(struct seq_file *sf, void *v)
|
|
{
|
|
cpu_uclamp_print(sf, UCLAMP_MIN);
|
|
return 0;
|
|
}
|
|
|
|
static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
|
|
{
|
|
cpu_uclamp_print(sf, UCLAMP_MAX);
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_UCLAMP_TASK_GROUP */
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cftype, u64 shareval)
|
|
{
|
|
if (shareval > scale_load_down(ULONG_MAX))
|
|
shareval = MAX_SHARES;
|
|
return sched_group_set_shares(css_tg(css), scale_load(shareval));
|
|
}
|
|
|
|
static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
|
|
return (u64) scale_load_down(tg->shares);
|
|
}
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
static DEFINE_MUTEX(cfs_constraints_mutex);
|
|
|
|
const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
|
|
static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
|
|
/* More than 203 days if BW_SHIFT equals 20. */
|
|
static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC;
|
|
|
|
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
|
|
|
|
static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
|
|
{
|
|
int i, ret = 0, runtime_enabled, runtime_was_enabled;
|
|
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
|
|
|
|
if (tg == &root_task_group)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Ensure we have at some amount of bandwidth every period. This is
|
|
* to prevent reaching a state of large arrears when throttled via
|
|
* entity_tick() resulting in prolonged exit starvation.
|
|
*/
|
|
if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Likewise, bound things on the otherside by preventing insane quota
|
|
* periods. This also allows us to normalize in computing quota
|
|
* feasibility.
|
|
*/
|
|
if (period > max_cfs_quota_period)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Bound quota to defend quota against overflow during bandwidth shift.
|
|
*/
|
|
if (quota != RUNTIME_INF && quota > max_cfs_runtime)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Prevent race between setting of cfs_rq->runtime_enabled and
|
|
* unthrottle_offline_cfs_rqs().
|
|
*/
|
|
get_online_cpus();
|
|
mutex_lock(&cfs_constraints_mutex);
|
|
ret = __cfs_schedulable(tg, period, quota);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
runtime_enabled = quota != RUNTIME_INF;
|
|
runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
|
|
/*
|
|
* If we need to toggle cfs_bandwidth_used, off->on must occur
|
|
* before making related changes, and on->off must occur afterwards
|
|
*/
|
|
if (runtime_enabled && !runtime_was_enabled)
|
|
cfs_bandwidth_usage_inc();
|
|
raw_spin_lock_irq(&cfs_b->lock);
|
|
cfs_b->period = ns_to_ktime(period);
|
|
cfs_b->quota = quota;
|
|
|
|
__refill_cfs_bandwidth_runtime(cfs_b);
|
|
|
|
/* Restart the period timer (if active) to handle new period expiry: */
|
|
if (runtime_enabled)
|
|
start_cfs_bandwidth(cfs_b);
|
|
|
|
raw_spin_unlock_irq(&cfs_b->lock);
|
|
|
|
for_each_online_cpu(i) {
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[i];
|
|
struct rq *rq = cfs_rq->rq;
|
|
struct rq_flags rf;
|
|
|
|
rq_lock_irq(rq, &rf);
|
|
cfs_rq->runtime_enabled = runtime_enabled;
|
|
cfs_rq->runtime_remaining = 0;
|
|
|
|
if (cfs_rq->throttled)
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
rq_unlock_irq(rq, &rf);
|
|
}
|
|
if (runtime_was_enabled && !runtime_enabled)
|
|
cfs_bandwidth_usage_dec();
|
|
out_unlock:
|
|
mutex_unlock(&cfs_constraints_mutex);
|
|
put_online_cpus();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
|
|
{
|
|
u64 quota, period;
|
|
|
|
period = ktime_to_ns(tg->cfs_bandwidth.period);
|
|
if (cfs_quota_us < 0)
|
|
quota = RUNTIME_INF;
|
|
else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
|
|
quota = (u64)cfs_quota_us * NSEC_PER_USEC;
|
|
else
|
|
return -EINVAL;
|
|
|
|
return tg_set_cfs_bandwidth(tg, period, quota);
|
|
}
|
|
|
|
static long tg_get_cfs_quota(struct task_group *tg)
|
|
{
|
|
u64 quota_us;
|
|
|
|
if (tg->cfs_bandwidth.quota == RUNTIME_INF)
|
|
return -1;
|
|
|
|
quota_us = tg->cfs_bandwidth.quota;
|
|
do_div(quota_us, NSEC_PER_USEC);
|
|
|
|
return quota_us;
|
|
}
|
|
|
|
static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
|
|
{
|
|
u64 quota, period;
|
|
|
|
if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
|
|
return -EINVAL;
|
|
|
|
period = (u64)cfs_period_us * NSEC_PER_USEC;
|
|
quota = tg->cfs_bandwidth.quota;
|
|
|
|
return tg_set_cfs_bandwidth(tg, period, quota);
|
|
}
|
|
|
|
static long tg_get_cfs_period(struct task_group *tg)
|
|
{
|
|
u64 cfs_period_us;
|
|
|
|
cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
|
|
do_div(cfs_period_us, NSEC_PER_USEC);
|
|
|
|
return cfs_period_us;
|
|
}
|
|
|
|
static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return tg_get_cfs_quota(css_tg(css));
|
|
}
|
|
|
|
static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
|
|
struct cftype *cftype, s64 cfs_quota_us)
|
|
{
|
|
return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
|
|
}
|
|
|
|
static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return tg_get_cfs_period(css_tg(css));
|
|
}
|
|
|
|
static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cftype, u64 cfs_period_us)
|
|
{
|
|
return tg_set_cfs_period(css_tg(css), cfs_period_us);
|
|
}
|
|
|
|
struct cfs_schedulable_data {
|
|
struct task_group *tg;
|
|
u64 period, quota;
|
|
};
|
|
|
|
/*
|
|
* normalize group quota/period to be quota/max_period
|
|
* note: units are usecs
|
|
*/
|
|
static u64 normalize_cfs_quota(struct task_group *tg,
|
|
struct cfs_schedulable_data *d)
|
|
{
|
|
u64 quota, period;
|
|
|
|
if (tg == d->tg) {
|
|
period = d->period;
|
|
quota = d->quota;
|
|
} else {
|
|
period = tg_get_cfs_period(tg);
|
|
quota = tg_get_cfs_quota(tg);
|
|
}
|
|
|
|
/* note: these should typically be equivalent */
|
|
if (quota == RUNTIME_INF || quota == -1)
|
|
return RUNTIME_INF;
|
|
|
|
return to_ratio(period, quota);
|
|
}
|
|
|
|
static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
|
|
{
|
|
struct cfs_schedulable_data *d = data;
|
|
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
|
|
s64 quota = 0, parent_quota = -1;
|
|
|
|
if (!tg->parent) {
|
|
quota = RUNTIME_INF;
|
|
} else {
|
|
struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
|
|
|
|
quota = normalize_cfs_quota(tg, d);
|
|
parent_quota = parent_b->hierarchical_quota;
|
|
|
|
/*
|
|
* Ensure max(child_quota) <= parent_quota. On cgroup2,
|
|
* always take the min. On cgroup1, only inherit when no
|
|
* limit is set:
|
|
*/
|
|
if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
|
|
quota = min(quota, parent_quota);
|
|
} else {
|
|
if (quota == RUNTIME_INF)
|
|
quota = parent_quota;
|
|
else if (parent_quota != RUNTIME_INF && quota > parent_quota)
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
cfs_b->hierarchical_quota = quota;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
|
|
{
|
|
int ret;
|
|
struct cfs_schedulable_data data = {
|
|
.tg = tg,
|
|
.period = period,
|
|
.quota = quota,
|
|
};
|
|
|
|
if (quota != RUNTIME_INF) {
|
|
do_div(data.period, NSEC_PER_USEC);
|
|
do_div(data.quota, NSEC_PER_USEC);
|
|
}
|
|
|
|
rcu_read_lock();
|
|
ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
|
|
rcu_read_unlock();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
|
|
{
|
|
struct task_group *tg = css_tg(seq_css(sf));
|
|
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
|
|
|
|
seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
|
|
seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
|
|
seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
|
|
|
|
if (schedstat_enabled() && tg != &root_task_group) {
|
|
u64 ws = 0;
|
|
int i;
|
|
|
|
for_each_possible_cpu(i)
|
|
ws += schedstat_val(tg->se[i]->statistics.wait_sum);
|
|
|
|
seq_printf(sf, "wait_sum %llu\n", ws);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_CFS_BANDWIDTH */
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, s64 val)
|
|
{
|
|
return sched_group_set_rt_runtime(css_tg(css), val);
|
|
}
|
|
|
|
static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return sched_group_rt_runtime(css_tg(css));
|
|
}
|
|
|
|
static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
|
|
struct cftype *cftype, u64 rt_period_us)
|
|
{
|
|
return sched_group_set_rt_period(css_tg(css), rt_period_us);
|
|
}
|
|
|
|
static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return sched_group_rt_period(css_tg(css));
|
|
}
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
static struct cftype cpu_legacy_files[] = {
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
{
|
|
.name = "shares",
|
|
.read_u64 = cpu_shares_read_u64,
|
|
.write_u64 = cpu_shares_write_u64,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
{
|
|
.name = "cfs_quota_us",
|
|
.read_s64 = cpu_cfs_quota_read_s64,
|
|
.write_s64 = cpu_cfs_quota_write_s64,
|
|
},
|
|
{
|
|
.name = "cfs_period_us",
|
|
.read_u64 = cpu_cfs_period_read_u64,
|
|
.write_u64 = cpu_cfs_period_write_u64,
|
|
},
|
|
{
|
|
.name = "stat",
|
|
.seq_show = cpu_cfs_stat_show,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
{
|
|
.name = "rt_runtime_us",
|
|
.read_s64 = cpu_rt_runtime_read,
|
|
.write_s64 = cpu_rt_runtime_write,
|
|
},
|
|
{
|
|
.name = "rt_period_us",
|
|
.read_u64 = cpu_rt_period_read_uint,
|
|
.write_u64 = cpu_rt_period_write_uint,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
{
|
|
.name = "uclamp.min",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cpu_uclamp_min_show,
|
|
.write = cpu_uclamp_min_write,
|
|
},
|
|
{
|
|
.name = "uclamp.max",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cpu_uclamp_max_show,
|
|
.write = cpu_uclamp_max_write,
|
|
},
|
|
#endif
|
|
{ } /* Terminate */
|
|
};
|
|
|
|
static int cpu_extra_stat_show(struct seq_file *sf,
|
|
struct cgroup_subsys_state *css)
|
|
{
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
|
|
u64 throttled_usec;
|
|
|
|
throttled_usec = cfs_b->throttled_time;
|
|
do_div(throttled_usec, NSEC_PER_USEC);
|
|
|
|
seq_printf(sf, "nr_periods %d\n"
|
|
"nr_throttled %d\n"
|
|
"throttled_usec %llu\n",
|
|
cfs_b->nr_periods, cfs_b->nr_throttled,
|
|
throttled_usec);
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
struct task_group *tg = css_tg(css);
|
|
u64 weight = scale_load_down(tg->shares);
|
|
|
|
return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
|
|
}
|
|
|
|
static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 weight)
|
|
{
|
|
/*
|
|
* cgroup weight knobs should use the common MIN, DFL and MAX
|
|
* values which are 1, 100 and 10000 respectively. While it loses
|
|
* a bit of range on both ends, it maps pretty well onto the shares
|
|
* value used by scheduler and the round-trip conversions preserve
|
|
* the original value over the entire range.
|
|
*/
|
|
if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
|
|
return -ERANGE;
|
|
|
|
weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
|
|
|
|
return sched_group_set_shares(css_tg(css), scale_load(weight));
|
|
}
|
|
|
|
static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
unsigned long weight = scale_load_down(css_tg(css)->shares);
|
|
int last_delta = INT_MAX;
|
|
int prio, delta;
|
|
|
|
/* find the closest nice value to the current weight */
|
|
for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
|
|
delta = abs(sched_prio_to_weight[prio] - weight);
|
|
if (delta >= last_delta)
|
|
break;
|
|
last_delta = delta;
|
|
}
|
|
|
|
return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
|
|
}
|
|
|
|
static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, s64 nice)
|
|
{
|
|
unsigned long weight;
|
|
int idx;
|
|
|
|
if (nice < MIN_NICE || nice > MAX_NICE)
|
|
return -ERANGE;
|
|
|
|
idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
|
|
idx = array_index_nospec(idx, 40);
|
|
weight = sched_prio_to_weight[idx];
|
|
|
|
return sched_group_set_shares(css_tg(css), scale_load(weight));
|
|
}
|
|
#endif
|
|
|
|
static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
|
|
long period, long quota)
|
|
{
|
|
if (quota < 0)
|
|
seq_puts(sf, "max");
|
|
else
|
|
seq_printf(sf, "%ld", quota);
|
|
|
|
seq_printf(sf, " %ld\n", period);
|
|
}
|
|
|
|
/* caller should put the current value in *@periodp before calling */
|
|
static int __maybe_unused cpu_period_quota_parse(char *buf,
|
|
u64 *periodp, u64 *quotap)
|
|
{
|
|
char tok[21]; /* U64_MAX */
|
|
|
|
if (sscanf(buf, "%20s %llu", tok, periodp) < 1)
|
|
return -EINVAL;
|
|
|
|
*periodp *= NSEC_PER_USEC;
|
|
|
|
if (sscanf(tok, "%llu", quotap))
|
|
*quotap *= NSEC_PER_USEC;
|
|
else if (!strcmp(tok, "max"))
|
|
*quotap = RUNTIME_INF;
|
|
else
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
static int cpu_max_show(struct seq_file *sf, void *v)
|
|
{
|
|
struct task_group *tg = css_tg(seq_css(sf));
|
|
|
|
cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t cpu_max_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
struct task_group *tg = css_tg(of_css(of));
|
|
u64 period = tg_get_cfs_period(tg);
|
|
u64 quota;
|
|
int ret;
|
|
|
|
ret = cpu_period_quota_parse(buf, &period, "a);
|
|
if (!ret)
|
|
ret = tg_set_cfs_bandwidth(tg, period, quota);
|
|
return ret ?: nbytes;
|
|
}
|
|
#endif
|
|
|
|
static struct cftype cpu_files[] = {
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
{
|
|
.name = "weight",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.read_u64 = cpu_weight_read_u64,
|
|
.write_u64 = cpu_weight_write_u64,
|
|
},
|
|
{
|
|
.name = "weight.nice",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.read_s64 = cpu_weight_nice_read_s64,
|
|
.write_s64 = cpu_weight_nice_write_s64,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
{
|
|
.name = "max",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cpu_max_show,
|
|
.write = cpu_max_write,
|
|
},
|
|
#endif
|
|
#ifdef CONFIG_UCLAMP_TASK_GROUP
|
|
{
|
|
.name = "uclamp.min",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cpu_uclamp_min_show,
|
|
.write = cpu_uclamp_min_write,
|
|
},
|
|
{
|
|
.name = "uclamp.max",
|
|
.flags = CFTYPE_NOT_ON_ROOT,
|
|
.seq_show = cpu_uclamp_max_show,
|
|
.write = cpu_uclamp_max_write,
|
|
},
|
|
#endif
|
|
{ } /* terminate */
|
|
};
|
|
|
|
struct cgroup_subsys cpu_cgrp_subsys = {
|
|
.css_alloc = cpu_cgroup_css_alloc,
|
|
.css_online = cpu_cgroup_css_online,
|
|
.css_released = cpu_cgroup_css_released,
|
|
.css_free = cpu_cgroup_css_free,
|
|
.css_extra_stat_show = cpu_extra_stat_show,
|
|
.fork = cpu_cgroup_fork,
|
|
.can_attach = cpu_cgroup_can_attach,
|
|
.attach = cpu_cgroup_attach,
|
|
.legacy_cftypes = cpu_legacy_files,
|
|
.dfl_cftypes = cpu_files,
|
|
.early_init = true,
|
|
.threaded = true,
|
|
};
|
|
|
|
#endif /* CONFIG_CGROUP_SCHED */
|
|
|
|
void dump_cpu_task(int cpu)
|
|
{
|
|
pr_info("Task dump for CPU %d:\n", cpu);
|
|
sched_show_task(cpu_curr(cpu));
|
|
}
|
|
|
|
/*
|
|
* Nice levels are multiplicative, with a gentle 10% change for every
|
|
* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
|
|
* nice 1, it will get ~10% less CPU time than another CPU-bound task
|
|
* that remained on nice 0.
|
|
*
|
|
* The "10% effect" is relative and cumulative: from _any_ nice level,
|
|
* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
|
|
* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
|
|
* If a task goes up by ~10% and another task goes down by ~10% then
|
|
* the relative distance between them is ~25%.)
|
|
*/
|
|
const int sched_prio_to_weight[40] = {
|
|
/* -20 */ 88761, 71755, 56483, 46273, 36291,
|
|
/* -15 */ 29154, 23254, 18705, 14949, 11916,
|
|
/* -10 */ 9548, 7620, 6100, 4904, 3906,
|
|
/* -5 */ 3121, 2501, 1991, 1586, 1277,
|
|
/* 0 */ 1024, 820, 655, 526, 423,
|
|
/* 5 */ 335, 272, 215, 172, 137,
|
|
/* 10 */ 110, 87, 70, 56, 45,
|
|
/* 15 */ 36, 29, 23, 18, 15,
|
|
};
|
|
|
|
/*
|
|
* Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
|
|
*
|
|
* In cases where the weight does not change often, we can use the
|
|
* precalculated inverse to speed up arithmetics by turning divisions
|
|
* into multiplications:
|
|
*/
|
|
const u32 sched_prio_to_wmult[40] = {
|
|
/* -20 */ 48388, 59856, 76040, 92818, 118348,
|
|
/* -15 */ 147320, 184698, 229616, 287308, 360437,
|
|
/* -10 */ 449829, 563644, 704093, 875809, 1099582,
|
|
/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
|
|
/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
|
|
/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
|
|
/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
|
|
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
|
|
};
|
|
|
|
void call_trace_sched_update_nr_running(struct rq *rq, int count)
|
|
{
|
|
trace_sched_update_nr_running_tp(rq, count);
|
|
}
|