6925 lines
174 KiB
C
6925 lines
174 KiB
C
/*
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* kernel/sched.c
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*
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* Kernel scheduler 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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* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
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* make semaphores SMP safe
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* 1998-11-19 Implemented schedule_timeout() and related stuff
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* by Andrea Arcangeli
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* 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
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* hybrid priority-list and round-robin design with
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* an array-switch method of distributing timeslices
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* and per-CPU runqueues. Cleanups and useful suggestions
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* by Davide Libenzi, preemptible kernel bits by Robert Love.
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* 2003-09-03 Interactivity tuning by Con Kolivas.
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* 2004-04-02 Scheduler domains code by Nick Piggin
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*/
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/nmi.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include <linux/highmem.h>
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#include <linux/smp_lock.h>
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#include <asm/mmu_context.h>
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#include <linux/interrupt.h>
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#include <linux/capability.h>
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#include <linux/completion.h>
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#include <linux/kernel_stat.h>
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#include <linux/debug_locks.h>
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#include <linux/security.h>
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#include <linux/notifier.h>
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#include <linux/profile.h>
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#include <linux/freezer.h>
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#include <linux/vmalloc.h>
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#include <linux/blkdev.h>
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#include <linux/delay.h>
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#include <linux/smp.h>
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#include <linux/threads.h>
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#include <linux/timer.h>
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#include <linux/rcupdate.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/percpu.h>
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#include <linux/kthread.h>
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#include <linux/seq_file.h>
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#include <linux/syscalls.h>
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#include <linux/times.h>
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#include <linux/tsacct_kern.h>
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#include <linux/kprobes.h>
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#include <linux/delayacct.h>
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#include <asm/tlb.h>
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#include <asm/unistd.h>
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/*
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* Scheduler clock - returns current time in nanosec units.
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* This is default implementation.
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* Architectures and sub-architectures can override this.
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*/
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unsigned long long __attribute__((weak)) sched_clock(void)
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{
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return (unsigned long long)jiffies * (1000000000 / HZ);
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}
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/*
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* Convert user-nice values [ -20 ... 0 ... 19 ]
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* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
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* and back.
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*/
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#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
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#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
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#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
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/*
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* 'User priority' is the nice value converted to something we
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* can work with better when scaling various scheduler parameters,
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* it's a [ 0 ... 39 ] range.
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*/
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#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
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#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
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#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
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/*
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* Some helpers for converting nanosecond timing to jiffy resolution
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*/
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#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
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#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
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/*
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* These are the 'tuning knobs' of the scheduler:
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*
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* Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
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* default timeslice is 100 msecs, maximum timeslice is 800 msecs.
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* Timeslices get refilled after they expire.
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*/
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#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
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#define DEF_TIMESLICE (100 * HZ / 1000)
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#define ON_RUNQUEUE_WEIGHT 30
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#define CHILD_PENALTY 95
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#define PARENT_PENALTY 100
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#define EXIT_WEIGHT 3
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#define PRIO_BONUS_RATIO 25
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#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
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#define INTERACTIVE_DELTA 2
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#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
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#define STARVATION_LIMIT (MAX_SLEEP_AVG)
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#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
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/*
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* If a task is 'interactive' then we reinsert it in the active
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* array after it has expired its current timeslice. (it will not
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* continue to run immediately, it will still roundrobin with
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* other interactive tasks.)
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*
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* This part scales the interactivity limit depending on niceness.
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*
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* We scale it linearly, offset by the INTERACTIVE_DELTA delta.
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* Here are a few examples of different nice levels:
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*
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* TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
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* TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
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* TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
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* TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
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* TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
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*
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* (the X axis represents the possible -5 ... 0 ... +5 dynamic
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* priority range a task can explore, a value of '1' means the
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* task is rated interactive.)
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*
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* Ie. nice +19 tasks can never get 'interactive' enough to be
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* reinserted into the active array. And only heavily CPU-hog nice -20
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* tasks will be expired. Default nice 0 tasks are somewhere between,
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* it takes some effort for them to get interactive, but it's not
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* too hard.
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*/
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#define CURRENT_BONUS(p) \
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(NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
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MAX_SLEEP_AVG)
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#define GRANULARITY (10 * HZ / 1000 ? : 1)
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#ifdef CONFIG_SMP
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#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
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(1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
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num_online_cpus())
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#else
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#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
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(1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
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#endif
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#define SCALE(v1,v1_max,v2_max) \
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(v1) * (v2_max) / (v1_max)
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#define DELTA(p) \
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(SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
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INTERACTIVE_DELTA)
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#define TASK_INTERACTIVE(p) \
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((p)->prio <= (p)->static_prio - DELTA(p))
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#define INTERACTIVE_SLEEP(p) \
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(JIFFIES_TO_NS(MAX_SLEEP_AVG * \
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(MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
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#define TASK_PREEMPTS_CURR(p, rq) \
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((p)->prio < (rq)->curr->prio)
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#define SCALE_PRIO(x, prio) \
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max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
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static unsigned int static_prio_timeslice(int static_prio)
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{
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if (static_prio < NICE_TO_PRIO(0))
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return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
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else
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return SCALE_PRIO(DEF_TIMESLICE, static_prio);
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}
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/*
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* task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
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* to time slice values: [800ms ... 100ms ... 5ms]
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*
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* The higher a thread's priority, the bigger timeslices
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* it gets during one round of execution. But even the lowest
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* priority thread gets MIN_TIMESLICE worth of execution time.
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*/
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static inline unsigned int task_timeslice(struct task_struct *p)
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{
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return static_prio_timeslice(p->static_prio);
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}
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/*
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* These are the runqueue data structures:
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*/
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struct prio_array {
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unsigned int nr_active;
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DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */
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struct list_head queue[MAX_PRIO];
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};
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/*
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* This is the main, per-CPU runqueue data structure.
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*
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* Locking rule: those places that want to lock multiple runqueues
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* (such as the load balancing or the thread migration code), lock
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* acquire operations must be ordered by ascending &runqueue.
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*/
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struct rq {
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spinlock_t lock;
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/*
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* nr_running and cpu_load should be in the same cacheline because
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* remote CPUs use both these fields when doing load calculation.
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*/
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unsigned long nr_running;
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unsigned long raw_weighted_load;
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#ifdef CONFIG_SMP
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unsigned long cpu_load[3];
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#endif
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unsigned long long nr_switches;
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/*
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* This is part of a global counter where only the total sum
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* over all CPUs matters. A task can increase this counter on
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* one CPU and if it got migrated afterwards it may decrease
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* it on another CPU. Always updated under the runqueue lock:
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*/
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unsigned long nr_uninterruptible;
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unsigned long expired_timestamp;
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/* Cached timestamp set by update_cpu_clock() */
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unsigned long long most_recent_timestamp;
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struct task_struct *curr, *idle;
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unsigned long next_balance;
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struct mm_struct *prev_mm;
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struct prio_array *active, *expired, arrays[2];
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int best_expired_prio;
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atomic_t nr_iowait;
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#ifdef CONFIG_SMP
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struct sched_domain *sd;
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/* For active balancing */
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int active_balance;
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int push_cpu;
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int cpu; /* cpu of this runqueue */
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struct task_struct *migration_thread;
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struct list_head migration_queue;
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#endif
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#ifdef CONFIG_SCHEDSTATS
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/* latency stats */
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struct sched_info rq_sched_info;
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/* sys_sched_yield() stats */
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unsigned long yld_exp_empty;
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unsigned long yld_act_empty;
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unsigned long yld_both_empty;
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unsigned long yld_cnt;
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/* schedule() stats */
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unsigned long sched_switch;
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unsigned long sched_cnt;
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unsigned long sched_goidle;
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/* try_to_wake_up() stats */
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unsigned long ttwu_cnt;
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unsigned long ttwu_local;
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#endif
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struct lock_class_key rq_lock_key;
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};
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static DEFINE_PER_CPU(struct rq, runqueues);
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static inline int cpu_of(struct rq *rq)
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{
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#ifdef CONFIG_SMP
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return rq->cpu;
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#else
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return 0;
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#endif
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}
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/*
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* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
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* See detach_destroy_domains: synchronize_sched for details.
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*
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* The domain tree of any CPU may only be accessed from within
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* preempt-disabled sections.
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*/
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#define for_each_domain(cpu, __sd) \
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for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
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#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
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#define this_rq() (&__get_cpu_var(runqueues))
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#define task_rq(p) cpu_rq(task_cpu(p))
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#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
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#ifndef prepare_arch_switch
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# define prepare_arch_switch(next) do { } while (0)
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#endif
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#ifndef finish_arch_switch
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# define finish_arch_switch(prev) do { } while (0)
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#endif
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#ifndef __ARCH_WANT_UNLOCKED_CTXSW
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static inline int task_running(struct rq *rq, struct task_struct *p)
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{
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return rq->curr == p;
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}
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static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
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{
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}
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static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
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{
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#ifdef CONFIG_DEBUG_SPINLOCK
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/* this is a valid case when another task releases the spinlock */
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rq->lock.owner = current;
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#endif
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/*
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* If we are tracking spinlock dependencies then we have to
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* fix up the runqueue lock - which gets 'carried over' from
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* prev into current:
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*/
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spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
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spin_unlock_irq(&rq->lock);
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}
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#else /* __ARCH_WANT_UNLOCKED_CTXSW */
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static inline int task_running(struct rq *rq, struct task_struct *p)
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{
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#ifdef CONFIG_SMP
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return p->oncpu;
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#else
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return rq->curr == p;
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#endif
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}
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static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
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{
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#ifdef CONFIG_SMP
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/*
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* We can optimise this out completely for !SMP, because the
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* SMP rebalancing from interrupt is the only thing that cares
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* here.
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*/
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next->oncpu = 1;
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#endif
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#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
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spin_unlock_irq(&rq->lock);
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#else
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spin_unlock(&rq->lock);
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#endif
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}
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static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
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{
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#ifdef CONFIG_SMP
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/*
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* After ->oncpu is cleared, the task can be moved to a different CPU.
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* We must ensure this doesn't happen until the switch is completely
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* finished.
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*/
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smp_wmb();
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prev->oncpu = 0;
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#endif
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#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
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local_irq_enable();
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#endif
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}
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#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
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|
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/*
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* __task_rq_lock - lock the runqueue a given task resides on.
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* Must be called interrupts disabled.
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*/
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static inline struct rq *__task_rq_lock(struct task_struct *p)
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__acquires(rq->lock)
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{
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struct rq *rq;
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repeat_lock_task:
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rq = task_rq(p);
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spin_lock(&rq->lock);
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if (unlikely(rq != task_rq(p))) {
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spin_unlock(&rq->lock);
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goto repeat_lock_task;
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}
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return rq;
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}
|
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|
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/*
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* task_rq_lock - lock the runqueue a given task resides on and disable
|
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* interrupts. Note the ordering: we can safely lookup the task_rq without
|
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* explicitly disabling preemption.
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*/
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static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
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__acquires(rq->lock)
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{
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struct rq *rq;
|
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|
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repeat_lock_task:
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local_irq_save(*flags);
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rq = task_rq(p);
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spin_lock(&rq->lock);
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if (unlikely(rq != task_rq(p))) {
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spin_unlock_irqrestore(&rq->lock, *flags);
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goto repeat_lock_task;
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}
|
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return rq;
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}
|
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|
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static inline void __task_rq_unlock(struct rq *rq)
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__releases(rq->lock)
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{
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spin_unlock(&rq->lock);
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}
|
|
|
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static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
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__releases(rq->lock)
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{
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spin_unlock_irqrestore(&rq->lock, *flags);
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}
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
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/*
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* bump this up when changing the output format or the meaning of an existing
|
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* format, so that tools can adapt (or abort)
|
|
*/
|
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#define SCHEDSTAT_VERSION 14
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|
|
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static int show_schedstat(struct seq_file *seq, void *v)
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|
{
|
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int cpu;
|
|
|
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seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
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seq_printf(seq, "timestamp %lu\n", jiffies);
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for_each_online_cpu(cpu) {
|
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struct rq *rq = cpu_rq(cpu);
|
|
#ifdef CONFIG_SMP
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|
struct sched_domain *sd;
|
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int dcnt = 0;
|
|
#endif
|
|
|
|
/* runqueue-specific stats */
|
|
seq_printf(seq,
|
|
"cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
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cpu, rq->yld_both_empty,
|
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rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
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|
rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
|
|
rq->ttwu_cnt, rq->ttwu_local,
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rq->rq_sched_info.cpu_time,
|
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rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
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|
|
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seq_printf(seq, "\n");
|
|
|
|
#ifdef CONFIG_SMP
|
|
/* domain-specific stats */
|
|
preempt_disable();
|
|
for_each_domain(cpu, sd) {
|
|
enum idle_type itype;
|
|
char mask_str[NR_CPUS];
|
|
|
|
cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
|
|
seq_printf(seq, "domain%d %s", dcnt++, mask_str);
|
|
for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
|
|
itype++) {
|
|
seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu "
|
|
"%lu",
|
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sd->lb_cnt[itype],
|
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sd->lb_balanced[itype],
|
|
sd->lb_failed[itype],
|
|
sd->lb_imbalance[itype],
|
|
sd->lb_gained[itype],
|
|
sd->lb_hot_gained[itype],
|
|
sd->lb_nobusyq[itype],
|
|
sd->lb_nobusyg[itype]);
|
|
}
|
|
seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu"
|
|
" %lu %lu %lu\n",
|
|
sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
|
|
sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
|
|
sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
|
|
sd->ttwu_wake_remote, sd->ttwu_move_affine,
|
|
sd->ttwu_move_balance);
|
|
}
|
|
preempt_enable();
|
|
#endif
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int schedstat_open(struct inode *inode, struct file *file)
|
|
{
|
|
unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
|
|
char *buf = kmalloc(size, GFP_KERNEL);
|
|
struct seq_file *m;
|
|
int res;
|
|
|
|
if (!buf)
|
|
return -ENOMEM;
|
|
res = single_open(file, show_schedstat, NULL);
|
|
if (!res) {
|
|
m = file->private_data;
|
|
m->buf = buf;
|
|
m->size = size;
|
|
} else
|
|
kfree(buf);
|
|
return res;
|
|
}
|
|
|
|
const struct file_operations proc_schedstat_operations = {
|
|
.open = schedstat_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
/*
|
|
* Expects runqueue lock to be held for atomicity of update
|
|
*/
|
|
static inline void
|
|
rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
|
|
{
|
|
if (rq) {
|
|
rq->rq_sched_info.run_delay += delta_jiffies;
|
|
rq->rq_sched_info.pcnt++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Expects runqueue lock to be held for atomicity of update
|
|
*/
|
|
static inline void
|
|
rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
|
|
{
|
|
if (rq)
|
|
rq->rq_sched_info.cpu_time += delta_jiffies;
|
|
}
|
|
# define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
|
|
# define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
|
|
#else /* !CONFIG_SCHEDSTATS */
|
|
static inline void
|
|
rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
|
|
{}
|
|
static inline void
|
|
rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
|
|
{}
|
|
# define schedstat_inc(rq, field) do { } while (0)
|
|
# define schedstat_add(rq, field, amt) do { } while (0)
|
|
#endif
|
|
|
|
/*
|
|
* this_rq_lock - lock this runqueue and disable interrupts.
|
|
*/
|
|
static inline struct rq *this_rq_lock(void)
|
|
__acquires(rq->lock)
|
|
{
|
|
struct rq *rq;
|
|
|
|
local_irq_disable();
|
|
rq = this_rq();
|
|
spin_lock(&rq->lock);
|
|
|
|
return rq;
|
|
}
|
|
|
|
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
|
|
/*
|
|
* Called when a process is dequeued from the active array and given
|
|
* the cpu. We should note that with the exception of interactive
|
|
* tasks, the expired queue will become the active queue after the active
|
|
* queue is empty, without explicitly dequeuing and requeuing tasks in the
|
|
* expired queue. (Interactive tasks may be requeued directly to the
|
|
* active queue, thus delaying tasks in the expired queue from running;
|
|
* see scheduler_tick()).
|
|
*
|
|
* This function is only called from sched_info_arrive(), rather than
|
|
* dequeue_task(). Even though a task may be queued and dequeued multiple
|
|
* times as it is shuffled about, we're really interested in knowing how
|
|
* long it was from the *first* time it was queued to the time that it
|
|
* finally hit a cpu.
|
|
*/
|
|
static inline void sched_info_dequeued(struct task_struct *t)
|
|
{
|
|
t->sched_info.last_queued = 0;
|
|
}
|
|
|
|
/*
|
|
* Called when a task finally hits the cpu. We can now calculate how
|
|
* long it was waiting to run. We also note when it began so that we
|
|
* can keep stats on how long its timeslice is.
|
|
*/
|
|
static void sched_info_arrive(struct task_struct *t)
|
|
{
|
|
unsigned long now = jiffies, delta_jiffies = 0;
|
|
|
|
if (t->sched_info.last_queued)
|
|
delta_jiffies = now - t->sched_info.last_queued;
|
|
sched_info_dequeued(t);
|
|
t->sched_info.run_delay += delta_jiffies;
|
|
t->sched_info.last_arrival = now;
|
|
t->sched_info.pcnt++;
|
|
|
|
rq_sched_info_arrive(task_rq(t), delta_jiffies);
|
|
}
|
|
|
|
/*
|
|
* Called when a process is queued into either the active or expired
|
|
* array. The time is noted and later used to determine how long we
|
|
* had to wait for us to reach the cpu. Since the expired queue will
|
|
* become the active queue after active queue is empty, without dequeuing
|
|
* and requeuing any tasks, we are interested in queuing to either. It
|
|
* is unusual but not impossible for tasks to be dequeued and immediately
|
|
* requeued in the same or another array: this can happen in sched_yield(),
|
|
* set_user_nice(), and even load_balance() as it moves tasks from runqueue
|
|
* to runqueue.
|
|
*
|
|
* This function is only called from enqueue_task(), but also only updates
|
|
* the timestamp if it is already not set. It's assumed that
|
|
* sched_info_dequeued() will clear that stamp when appropriate.
|
|
*/
|
|
static inline void sched_info_queued(struct task_struct *t)
|
|
{
|
|
if (unlikely(sched_info_on()))
|
|
if (!t->sched_info.last_queued)
|
|
t->sched_info.last_queued = jiffies;
|
|
}
|
|
|
|
/*
|
|
* Called when a process ceases being the active-running process, either
|
|
* voluntarily or involuntarily. Now we can calculate how long we ran.
|
|
*/
|
|
static inline void sched_info_depart(struct task_struct *t)
|
|
{
|
|
unsigned long delta_jiffies = jiffies - t->sched_info.last_arrival;
|
|
|
|
t->sched_info.cpu_time += delta_jiffies;
|
|
rq_sched_info_depart(task_rq(t), delta_jiffies);
|
|
}
|
|
|
|
/*
|
|
* Called when tasks are switched involuntarily due, typically, to expiring
|
|
* their time slice. (This may also be called when switching to or from
|
|
* the idle task.) We are only called when prev != next.
|
|
*/
|
|
static inline void
|
|
__sched_info_switch(struct task_struct *prev, struct task_struct *next)
|
|
{
|
|
struct rq *rq = task_rq(prev);
|
|
|
|
/*
|
|
* prev now departs the cpu. It's not interesting to record
|
|
* stats about how efficient we were at scheduling the idle
|
|
* process, however.
|
|
*/
|
|
if (prev != rq->idle)
|
|
sched_info_depart(prev);
|
|
|
|
if (next != rq->idle)
|
|
sched_info_arrive(next);
|
|
}
|
|
static inline void
|
|
sched_info_switch(struct task_struct *prev, struct task_struct *next)
|
|
{
|
|
if (unlikely(sched_info_on()))
|
|
__sched_info_switch(prev, next);
|
|
}
|
|
#else
|
|
#define sched_info_queued(t) do { } while (0)
|
|
#define sched_info_switch(t, next) do { } while (0)
|
|
#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
|
|
|
|
/*
|
|
* Adding/removing a task to/from a priority array:
|
|
*/
|
|
static void dequeue_task(struct task_struct *p, struct prio_array *array)
|
|
{
|
|
array->nr_active--;
|
|
list_del(&p->run_list);
|
|
if (list_empty(array->queue + p->prio))
|
|
__clear_bit(p->prio, array->bitmap);
|
|
}
|
|
|
|
static void enqueue_task(struct task_struct *p, struct prio_array *array)
|
|
{
|
|
sched_info_queued(p);
|
|
list_add_tail(&p->run_list, array->queue + p->prio);
|
|
__set_bit(p->prio, array->bitmap);
|
|
array->nr_active++;
|
|
p->array = array;
|
|
}
|
|
|
|
/*
|
|
* Put task to the end of the run list without the overhead of dequeue
|
|
* followed by enqueue.
|
|
*/
|
|
static void requeue_task(struct task_struct *p, struct prio_array *array)
|
|
{
|
|
list_move_tail(&p->run_list, array->queue + p->prio);
|
|
}
|
|
|
|
static inline void
|
|
enqueue_task_head(struct task_struct *p, struct prio_array *array)
|
|
{
|
|
list_add(&p->run_list, array->queue + p->prio);
|
|
__set_bit(p->prio, array->bitmap);
|
|
array->nr_active++;
|
|
p->array = array;
|
|
}
|
|
|
|
/*
|
|
* __normal_prio - return the priority that is based on the static
|
|
* priority but is modified by bonuses/penalties.
|
|
*
|
|
* We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
|
|
* into the -5 ... 0 ... +5 bonus/penalty range.
|
|
*
|
|
* We use 25% of the full 0...39 priority range so that:
|
|
*
|
|
* 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
|
|
* 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
|
|
*
|
|
* Both properties are important to certain workloads.
|
|
*/
|
|
|
|
static inline int __normal_prio(struct task_struct *p)
|
|
{
|
|
int bonus, prio;
|
|
|
|
bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
|
|
|
|
prio = p->static_prio - bonus;
|
|
if (prio < MAX_RT_PRIO)
|
|
prio = MAX_RT_PRIO;
|
|
if (prio > MAX_PRIO-1)
|
|
prio = MAX_PRIO-1;
|
|
return prio;
|
|
}
|
|
|
|
/*
|
|
* To aid in avoiding the subversion of "niceness" due to uneven distribution
|
|
* of tasks with abnormal "nice" values across CPUs the contribution that
|
|
* each task makes to its run queue's load is weighted according to its
|
|
* scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
|
|
* scaled version of the new time slice allocation that they receive on time
|
|
* slice expiry etc.
|
|
*/
|
|
|
|
/*
|
|
* Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
|
|
* If static_prio_timeslice() is ever changed to break this assumption then
|
|
* this code will need modification
|
|
*/
|
|
#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
|
|
#define LOAD_WEIGHT(lp) \
|
|
(((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
|
|
#define PRIO_TO_LOAD_WEIGHT(prio) \
|
|
LOAD_WEIGHT(static_prio_timeslice(prio))
|
|
#define RTPRIO_TO_LOAD_WEIGHT(rp) \
|
|
(PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
|
|
|
|
static void set_load_weight(struct task_struct *p)
|
|
{
|
|
if (has_rt_policy(p)) {
|
|
#ifdef CONFIG_SMP
|
|
if (p == task_rq(p)->migration_thread)
|
|
/*
|
|
* The migration thread does the actual balancing.
|
|
* Giving its load any weight will skew balancing
|
|
* adversely.
|
|
*/
|
|
p->load_weight = 0;
|
|
else
|
|
#endif
|
|
p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
|
|
} else
|
|
p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
|
|
}
|
|
|
|
static inline void
|
|
inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
|
|
{
|
|
rq->raw_weighted_load += p->load_weight;
|
|
}
|
|
|
|
static inline void
|
|
dec_raw_weighted_load(struct rq *rq, const struct task_struct *p)
|
|
{
|
|
rq->raw_weighted_load -= p->load_weight;
|
|
}
|
|
|
|
static inline void inc_nr_running(struct task_struct *p, struct rq *rq)
|
|
{
|
|
rq->nr_running++;
|
|
inc_raw_weighted_load(rq, p);
|
|
}
|
|
|
|
static inline void dec_nr_running(struct task_struct *p, struct rq *rq)
|
|
{
|
|
rq->nr_running--;
|
|
dec_raw_weighted_load(rq, p);
|
|
}
|
|
|
|
/*
|
|
* 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 (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;
|
|
}
|
|
|
|
/*
|
|
* __activate_task - move a task to the runqueue.
|
|
*/
|
|
static void __activate_task(struct task_struct *p, struct rq *rq)
|
|
{
|
|
struct prio_array *target = rq->active;
|
|
|
|
if (batch_task(p))
|
|
target = rq->expired;
|
|
enqueue_task(p, target);
|
|
inc_nr_running(p, rq);
|
|
}
|
|
|
|
/*
|
|
* __activate_idle_task - move idle task to the _front_ of runqueue.
|
|
*/
|
|
static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
|
|
{
|
|
enqueue_task_head(p, rq->active);
|
|
inc_nr_running(p, rq);
|
|
}
|
|
|
|
/*
|
|
* Recalculate p->normal_prio and p->prio after having slept,
|
|
* updating the sleep-average too:
|
|
*/
|
|
static int recalc_task_prio(struct task_struct *p, unsigned long long now)
|
|
{
|
|
/* Caller must always ensure 'now >= p->timestamp' */
|
|
unsigned long sleep_time = now - p->timestamp;
|
|
|
|
if (batch_task(p))
|
|
sleep_time = 0;
|
|
|
|
if (likely(sleep_time > 0)) {
|
|
/*
|
|
* This ceiling is set to the lowest priority that would allow
|
|
* a task to be reinserted into the active array on timeslice
|
|
* completion.
|
|
*/
|
|
unsigned long ceiling = INTERACTIVE_SLEEP(p);
|
|
|
|
if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
|
|
/*
|
|
* Prevents user tasks from achieving best priority
|
|
* with one single large enough sleep.
|
|
*/
|
|
p->sleep_avg = ceiling;
|
|
/*
|
|
* Using INTERACTIVE_SLEEP() as a ceiling places a
|
|
* nice(0) task 1ms sleep away from promotion, and
|
|
* gives it 700ms to round-robin with no chance of
|
|
* being demoted. This is more than generous, so
|
|
* mark this sleep as non-interactive to prevent the
|
|
* on-runqueue bonus logic from intervening should
|
|
* this task not receive cpu immediately.
|
|
*/
|
|
p->sleep_type = SLEEP_NONINTERACTIVE;
|
|
} else {
|
|
/*
|
|
* Tasks waking from uninterruptible sleep are
|
|
* limited in their sleep_avg rise as they
|
|
* are likely to be waiting on I/O
|
|
*/
|
|
if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) {
|
|
if (p->sleep_avg >= ceiling)
|
|
sleep_time = 0;
|
|
else if (p->sleep_avg + sleep_time >=
|
|
ceiling) {
|
|
p->sleep_avg = ceiling;
|
|
sleep_time = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This code gives a bonus to interactive tasks.
|
|
*
|
|
* The boost works by updating the 'average sleep time'
|
|
* value here, based on ->timestamp. The more time a
|
|
* task spends sleeping, the higher the average gets -
|
|
* and the higher the priority boost gets as well.
|
|
*/
|
|
p->sleep_avg += sleep_time;
|
|
|
|
}
|
|
if (p->sleep_avg > NS_MAX_SLEEP_AVG)
|
|
p->sleep_avg = NS_MAX_SLEEP_AVG;
|
|
}
|
|
|
|
return effective_prio(p);
|
|
}
|
|
|
|
/*
|
|
* activate_task - move a task to the runqueue and do priority recalculation
|
|
*
|
|
* Update all the scheduling statistics stuff. (sleep average
|
|
* calculation, priority modifiers, etc.)
|
|
*/
|
|
static void activate_task(struct task_struct *p, struct rq *rq, int local)
|
|
{
|
|
unsigned long long now;
|
|
|
|
if (rt_task(p))
|
|
goto out;
|
|
|
|
now = sched_clock();
|
|
#ifdef CONFIG_SMP
|
|
if (!local) {
|
|
/* Compensate for drifting sched_clock */
|
|
struct rq *this_rq = this_rq();
|
|
now = (now - this_rq->most_recent_timestamp)
|
|
+ rq->most_recent_timestamp;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Sleep time is in units of nanosecs, so shift by 20 to get a
|
|
* milliseconds-range estimation of the amount of time that the task
|
|
* spent sleeping:
|
|
*/
|
|
if (unlikely(prof_on == SLEEP_PROFILING)) {
|
|
if (p->state == TASK_UNINTERRUPTIBLE)
|
|
profile_hits(SLEEP_PROFILING, (void *)get_wchan(p),
|
|
(now - p->timestamp) >> 20);
|
|
}
|
|
|
|
p->prio = recalc_task_prio(p, now);
|
|
|
|
/*
|
|
* This checks to make sure it's not an uninterruptible task
|
|
* that is now waking up.
|
|
*/
|
|
if (p->sleep_type == SLEEP_NORMAL) {
|
|
/*
|
|
* Tasks which were woken up by interrupts (ie. hw events)
|
|
* are most likely of interactive nature. So we give them
|
|
* the credit of extending their sleep time to the period
|
|
* of time they spend on the runqueue, waiting for execution
|
|
* on a CPU, first time around:
|
|
*/
|
|
if (in_interrupt())
|
|
p->sleep_type = SLEEP_INTERRUPTED;
|
|
else {
|
|
/*
|
|
* Normal first-time wakeups get a credit too for
|
|
* on-runqueue time, but it will be weighted down:
|
|
*/
|
|
p->sleep_type = SLEEP_INTERACTIVE;
|
|
}
|
|
}
|
|
p->timestamp = now;
|
|
out:
|
|
__activate_task(p, rq);
|
|
}
|
|
|
|
/*
|
|
* deactivate_task - remove a task from the runqueue.
|
|
*/
|
|
static void deactivate_task(struct task_struct *p, struct rq *rq)
|
|
{
|
|
dec_nr_running(p, rq);
|
|
dequeue_task(p, p->array);
|
|
p->array = NULL;
|
|
}
|
|
|
|
/*
|
|
* resched_task - mark a 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.
|
|
*/
|
|
#ifdef CONFIG_SMP
|
|
|
|
#ifndef tsk_is_polling
|
|
#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
|
|
#endif
|
|
|
|
static void resched_task(struct task_struct *p)
|
|
{
|
|
int cpu;
|
|
|
|
assert_spin_locked(&task_rq(p)->lock);
|
|
|
|
if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
|
|
return;
|
|
|
|
set_tsk_thread_flag(p, TIF_NEED_RESCHED);
|
|
|
|
cpu = task_cpu(p);
|
|
if (cpu == smp_processor_id())
|
|
return;
|
|
|
|
/* NEED_RESCHED must be visible before we test polling */
|
|
smp_mb();
|
|
if (!tsk_is_polling(p))
|
|
smp_send_reschedule(cpu);
|
|
}
|
|
#else
|
|
static inline void resched_task(struct task_struct *p)
|
|
{
|
|
assert_spin_locked(&task_rq(p)->lock);
|
|
set_tsk_need_resched(p);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* task_curr - is this task currently executing on a CPU?
|
|
* @p: the task in question.
|
|
*/
|
|
inline int task_curr(const struct task_struct *p)
|
|
{
|
|
return cpu_curr(task_cpu(p)) == p;
|
|
}
|
|
|
|
/* Used instead of source_load when we know the type == 0 */
|
|
unsigned long weighted_cpuload(const int cpu)
|
|
{
|
|
return cpu_rq(cpu)->raw_weighted_load;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
struct migration_req {
|
|
struct list_head list;
|
|
|
|
struct task_struct *task;
|
|
int dest_cpu;
|
|
|
|
struct completion done;
|
|
};
|
|
|
|
/*
|
|
* The task's runqueue lock must be held.
|
|
* Returns true if you have to wait for migration thread.
|
|
*/
|
|
static int
|
|
migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
|
|
{
|
|
struct rq *rq = task_rq(p);
|
|
|
|
/*
|
|
* If the task is not on a runqueue (and not running), then
|
|
* it is sufficient to simply update the task's cpu field.
|
|
*/
|
|
if (!p->array && !task_running(rq, p)) {
|
|
set_task_cpu(p, dest_cpu);
|
|
return 0;
|
|
}
|
|
|
|
init_completion(&req->done);
|
|
req->task = p;
|
|
req->dest_cpu = dest_cpu;
|
|
list_add(&req->list, &rq->migration_queue);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* wait_task_inactive - wait for a thread to unschedule.
|
|
*
|
|
* 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.
|
|
*/
|
|
void wait_task_inactive(struct task_struct *p)
|
|
{
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
int preempted;
|
|
|
|
repeat:
|
|
rq = task_rq_lock(p, &flags);
|
|
/* Must be off runqueue entirely, not preempted. */
|
|
if (unlikely(p->array || task_running(rq, p))) {
|
|
/* If it's preempted, we yield. It could be a while. */
|
|
preempted = !task_running(rq, p);
|
|
task_rq_unlock(rq, &flags);
|
|
cpu_relax();
|
|
if (preempted)
|
|
yield();
|
|
goto repeat;
|
|
}
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/***
|
|
* 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 doesnt 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();
|
|
}
|
|
|
|
/*
|
|
* Return a low guess at the load of a migration-source cpu weighted
|
|
* according to the scheduling class and "nice" value.
|
|
*
|
|
* We want to under-estimate the load of migration sources, to
|
|
* balance conservatively.
|
|
*/
|
|
static inline unsigned long source_load(int cpu, int type)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (type == 0)
|
|
return rq->raw_weighted_load;
|
|
|
|
return min(rq->cpu_load[type-1], rq->raw_weighted_load);
|
|
}
|
|
|
|
/*
|
|
* Return a high guess at the load of a migration-target cpu weighted
|
|
* according to the scheduling class and "nice" value.
|
|
*/
|
|
static inline unsigned long target_load(int cpu, int type)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
if (type == 0)
|
|
return rq->raw_weighted_load;
|
|
|
|
return max(rq->cpu_load[type-1], rq->raw_weighted_load);
|
|
}
|
|
|
|
/*
|
|
* Return the average load per task on the cpu's run queue
|
|
*/
|
|
static inline unsigned long cpu_avg_load_per_task(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long n = rq->nr_running;
|
|
|
|
return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE;
|
|
}
|
|
|
|
/*
|
|
* find_idlest_group finds and returns the least busy CPU group within the
|
|
* domain.
|
|
*/
|
|
static struct sched_group *
|
|
find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
|
|
{
|
|
struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
|
|
unsigned long min_load = ULONG_MAX, this_load = 0;
|
|
int load_idx = sd->forkexec_idx;
|
|
int imbalance = 100 + (sd->imbalance_pct-100)/2;
|
|
|
|
do {
|
|
unsigned long load, avg_load;
|
|
int local_group;
|
|
int i;
|
|
|
|
/* Skip over this group if it has no CPUs allowed */
|
|
if (!cpus_intersects(group->cpumask, p->cpus_allowed))
|
|
goto nextgroup;
|
|
|
|
local_group = cpu_isset(this_cpu, group->cpumask);
|
|
|
|
/* Tally up the load of all CPUs in the group */
|
|
avg_load = 0;
|
|
|
|
for_each_cpu_mask(i, group->cpumask) {
|
|
/* Bias balancing toward cpus of our domain */
|
|
if (local_group)
|
|
load = source_load(i, load_idx);
|
|
else
|
|
load = target_load(i, load_idx);
|
|
|
|
avg_load += load;
|
|
}
|
|
|
|
/* Adjust by relative CPU power of the group */
|
|
avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
|
|
|
|
if (local_group) {
|
|
this_load = avg_load;
|
|
this = group;
|
|
} else if (avg_load < min_load) {
|
|
min_load = avg_load;
|
|
idlest = group;
|
|
}
|
|
nextgroup:
|
|
group = group->next;
|
|
} while (group != sd->groups);
|
|
|
|
if (!idlest || 100*this_load < imbalance*min_load)
|
|
return NULL;
|
|
return idlest;
|
|
}
|
|
|
|
/*
|
|
* find_idlest_cpu - find the idlest cpu among the cpus in group.
|
|
*/
|
|
static int
|
|
find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
|
|
{
|
|
cpumask_t tmp;
|
|
unsigned long load, min_load = ULONG_MAX;
|
|
int idlest = -1;
|
|
int i;
|
|
|
|
/* Traverse only the allowed CPUs */
|
|
cpus_and(tmp, group->cpumask, p->cpus_allowed);
|
|
|
|
for_each_cpu_mask(i, tmp) {
|
|
load = weighted_cpuload(i);
|
|
|
|
if (load < min_load || (load == min_load && i == this_cpu)) {
|
|
min_load = load;
|
|
idlest = i;
|
|
}
|
|
}
|
|
|
|
return idlest;
|
|
}
|
|
|
|
/*
|
|
* sched_balance_self: balance the current task (running on cpu) in domains
|
|
* that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
|
|
* SD_BALANCE_EXEC.
|
|
*
|
|
* Balance, ie. select the least loaded group.
|
|
*
|
|
* Returns the target CPU number, or the same CPU if no balancing is needed.
|
|
*
|
|
* preempt must be disabled.
|
|
*/
|
|
static int sched_balance_self(int cpu, int flag)
|
|
{
|
|
struct task_struct *t = current;
|
|
struct sched_domain *tmp, *sd = NULL;
|
|
|
|
for_each_domain(cpu, tmp) {
|
|
/*
|
|
* If power savings logic is enabled for a domain, stop there.
|
|
*/
|
|
if (tmp->flags & SD_POWERSAVINGS_BALANCE)
|
|
break;
|
|
if (tmp->flags & flag)
|
|
sd = tmp;
|
|
}
|
|
|
|
while (sd) {
|
|
cpumask_t span;
|
|
struct sched_group *group;
|
|
int new_cpu, weight;
|
|
|
|
if (!(sd->flags & flag)) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
span = sd->span;
|
|
group = find_idlest_group(sd, t, cpu);
|
|
if (!group) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
new_cpu = find_idlest_cpu(group, t, cpu);
|
|
if (new_cpu == -1 || new_cpu == cpu) {
|
|
/* Now try balancing at a lower domain level of cpu */
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
/* Now try balancing at a lower domain level of new_cpu */
|
|
cpu = new_cpu;
|
|
sd = NULL;
|
|
weight = cpus_weight(span);
|
|
for_each_domain(cpu, tmp) {
|
|
if (weight <= cpus_weight(tmp->span))
|
|
break;
|
|
if (tmp->flags & flag)
|
|
sd = tmp;
|
|
}
|
|
/* while loop will break here if sd == NULL */
|
|
}
|
|
|
|
return cpu;
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* wake_idle() will wake a task on an idle cpu if task->cpu is
|
|
* not idle and an idle cpu is available. The span of cpus to
|
|
* search starts with cpus closest then further out as needed,
|
|
* so we always favor a closer, idle cpu.
|
|
*
|
|
* Returns the CPU we should wake onto.
|
|
*/
|
|
#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
|
|
static int wake_idle(int cpu, struct task_struct *p)
|
|
{
|
|
cpumask_t tmp;
|
|
struct sched_domain *sd;
|
|
int i;
|
|
|
|
if (idle_cpu(cpu))
|
|
return cpu;
|
|
|
|
for_each_domain(cpu, sd) {
|
|
if (sd->flags & SD_WAKE_IDLE) {
|
|
cpus_and(tmp, sd->span, p->cpus_allowed);
|
|
for_each_cpu_mask(i, tmp) {
|
|
if (idle_cpu(i))
|
|
return i;
|
|
}
|
|
}
|
|
else
|
|
break;
|
|
}
|
|
return cpu;
|
|
}
|
|
#else
|
|
static inline int wake_idle(int cpu, struct task_struct *p)
|
|
{
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
/***
|
|
* try_to_wake_up - wake up a thread
|
|
* @p: the to-be-woken-up thread
|
|
* @state: the mask of task states that can be woken
|
|
* @sync: do a synchronous wakeup?
|
|
*
|
|
* Put it on the run-queue if it's not already there. The "current"
|
|
* thread is always on the run-queue (except when the actual
|
|
* re-schedule is in progress), and as such you're allowed to do
|
|
* the simpler "current->state = TASK_RUNNING" to mark yourself
|
|
* runnable without the overhead of this.
|
|
*
|
|
* returns failure only if the task is already active.
|
|
*/
|
|
static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
|
|
{
|
|
int cpu, this_cpu, success = 0;
|
|
unsigned long flags;
|
|
long old_state;
|
|
struct rq *rq;
|
|
#ifdef CONFIG_SMP
|
|
struct sched_domain *sd, *this_sd = NULL;
|
|
unsigned long load, this_load;
|
|
int new_cpu;
|
|
#endif
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
old_state = p->state;
|
|
if (!(old_state & state))
|
|
goto out;
|
|
|
|
if (p->array)
|
|
goto out_running;
|
|
|
|
cpu = task_cpu(p);
|
|
this_cpu = smp_processor_id();
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (unlikely(task_running(rq, p)))
|
|
goto out_activate;
|
|
|
|
new_cpu = cpu;
|
|
|
|
schedstat_inc(rq, ttwu_cnt);
|
|
if (cpu == this_cpu) {
|
|
schedstat_inc(rq, ttwu_local);
|
|
goto out_set_cpu;
|
|
}
|
|
|
|
for_each_domain(this_cpu, sd) {
|
|
if (cpu_isset(cpu, sd->span)) {
|
|
schedstat_inc(sd, ttwu_wake_remote);
|
|
this_sd = sd;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
|
|
goto out_set_cpu;
|
|
|
|
/*
|
|
* Check for affine wakeup and passive balancing possibilities.
|
|
*/
|
|
if (this_sd) {
|
|
int idx = this_sd->wake_idx;
|
|
unsigned int imbalance;
|
|
|
|
imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
|
|
|
|
load = source_load(cpu, idx);
|
|
this_load = target_load(this_cpu, idx);
|
|
|
|
new_cpu = this_cpu; /* Wake to this CPU if we can */
|
|
|
|
if (this_sd->flags & SD_WAKE_AFFINE) {
|
|
unsigned long tl = this_load;
|
|
unsigned long tl_per_task;
|
|
|
|
tl_per_task = cpu_avg_load_per_task(this_cpu);
|
|
|
|
/*
|
|
* If sync wakeup then subtract the (maximum possible)
|
|
* effect of the currently running task from the load
|
|
* of the current CPU:
|
|
*/
|
|
if (sync)
|
|
tl -= current->load_weight;
|
|
|
|
if ((tl <= load &&
|
|
tl + target_load(cpu, idx) <= tl_per_task) ||
|
|
100*(tl + p->load_weight) <= imbalance*load) {
|
|
/*
|
|
* This domain has SD_WAKE_AFFINE and
|
|
* p is cache cold in this domain, and
|
|
* there is no bad imbalance.
|
|
*/
|
|
schedstat_inc(this_sd, ttwu_move_affine);
|
|
goto out_set_cpu;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Start passive balancing when half the imbalance_pct
|
|
* limit is reached.
|
|
*/
|
|
if (this_sd->flags & SD_WAKE_BALANCE) {
|
|
if (imbalance*this_load <= 100*load) {
|
|
schedstat_inc(this_sd, ttwu_move_balance);
|
|
goto out_set_cpu;
|
|
}
|
|
}
|
|
}
|
|
|
|
new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
|
|
out_set_cpu:
|
|
new_cpu = wake_idle(new_cpu, p);
|
|
if (new_cpu != cpu) {
|
|
set_task_cpu(p, new_cpu);
|
|
task_rq_unlock(rq, &flags);
|
|
/* might preempt at this point */
|
|
rq = task_rq_lock(p, &flags);
|
|
old_state = p->state;
|
|
if (!(old_state & state))
|
|
goto out;
|
|
if (p->array)
|
|
goto out_running;
|
|
|
|
this_cpu = smp_processor_id();
|
|
cpu = task_cpu(p);
|
|
}
|
|
|
|
out_activate:
|
|
#endif /* CONFIG_SMP */
|
|
if (old_state == TASK_UNINTERRUPTIBLE) {
|
|
rq->nr_uninterruptible--;
|
|
/*
|
|
* Tasks on involuntary sleep don't earn
|
|
* sleep_avg beyond just interactive state.
|
|
*/
|
|
p->sleep_type = SLEEP_NONINTERACTIVE;
|
|
} else
|
|
|
|
/*
|
|
* Tasks that have marked their sleep as noninteractive get
|
|
* woken up with their sleep average not weighted in an
|
|
* interactive way.
|
|
*/
|
|
if (old_state & TASK_NONINTERACTIVE)
|
|
p->sleep_type = SLEEP_NONINTERACTIVE;
|
|
|
|
|
|
activate_task(p, rq, cpu == this_cpu);
|
|
/*
|
|
* Sync wakeups (i.e. those types of wakeups where the waker
|
|
* has indicated that it will leave the CPU in short order)
|
|
* don't trigger a preemption, if the woken up task will run on
|
|
* this cpu. (in this case the 'I will reschedule' promise of
|
|
* the waker guarantees that the freshly woken up task is going
|
|
* to be considered on this CPU.)
|
|
*/
|
|
if (!sync || cpu != this_cpu) {
|
|
if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
}
|
|
success = 1;
|
|
|
|
out_running:
|
|
p->state = TASK_RUNNING;
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
|
|
return success;
|
|
}
|
|
|
|
int fastcall wake_up_process(struct task_struct *p)
|
|
{
|
|
return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
|
|
TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
|
|
}
|
|
EXPORT_SYMBOL(wake_up_process);
|
|
|
|
int fastcall wake_up_state(struct task_struct *p, unsigned int state)
|
|
{
|
|
return try_to_wake_up(p, state, 0);
|
|
}
|
|
|
|
static void task_running_tick(struct rq *rq, struct task_struct *p);
|
|
/*
|
|
* Perform scheduler related setup for a newly forked process p.
|
|
* p is forked by current.
|
|
*/
|
|
void fastcall sched_fork(struct task_struct *p, int clone_flags)
|
|
{
|
|
int cpu = get_cpu();
|
|
|
|
#ifdef CONFIG_SMP
|
|
cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
|
|
#endif
|
|
set_task_cpu(p, cpu);
|
|
|
|
/*
|
|
* We mark the process as running here, but have not actually
|
|
* inserted it onto the runqueue yet. 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_RUNNING;
|
|
|
|
/*
|
|
* Make sure we do not leak PI boosting priority to the child:
|
|
*/
|
|
p->prio = current->normal_prio;
|
|
|
|
INIT_LIST_HEAD(&p->run_list);
|
|
p->array = NULL;
|
|
#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
|
|
if (unlikely(sched_info_on()))
|
|
memset(&p->sched_info, 0, sizeof(p->sched_info));
|
|
#endif
|
|
#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
|
|
p->oncpu = 0;
|
|
#endif
|
|
#ifdef CONFIG_PREEMPT
|
|
/* Want to start with kernel preemption disabled. */
|
|
task_thread_info(p)->preempt_count = 1;
|
|
#endif
|
|
/*
|
|
* Share the timeslice between parent and child, thus the
|
|
* total amount of pending timeslices in the system doesn't change,
|
|
* resulting in more scheduling fairness.
|
|
*/
|
|
local_irq_disable();
|
|
p->time_slice = (current->time_slice + 1) >> 1;
|
|
/*
|
|
* The remainder of the first timeslice might be recovered by
|
|
* the parent if the child exits early enough.
|
|
*/
|
|
p->first_time_slice = 1;
|
|
current->time_slice >>= 1;
|
|
p->timestamp = sched_clock();
|
|
if (unlikely(!current->time_slice)) {
|
|
/*
|
|
* This case is rare, it happens when the parent has only
|
|
* a single jiffy left from its timeslice. Taking the
|
|
* runqueue lock is not a problem.
|
|
*/
|
|
current->time_slice = 1;
|
|
task_running_tick(cpu_rq(cpu), current);
|
|
}
|
|
local_irq_enable();
|
|
put_cpu();
|
|
}
|
|
|
|
/*
|
|
* 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 fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
|
|
{
|
|
struct rq *rq, *this_rq;
|
|
unsigned long flags;
|
|
int this_cpu, cpu;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
BUG_ON(p->state != TASK_RUNNING);
|
|
this_cpu = smp_processor_id();
|
|
cpu = task_cpu(p);
|
|
|
|
/*
|
|
* We decrease the sleep average of forking parents
|
|
* and children as well, to keep max-interactive tasks
|
|
* from forking tasks that are max-interactive. The parent
|
|
* (current) is done further down, under its lock.
|
|
*/
|
|
p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
|
|
CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
|
|
|
|
p->prio = effective_prio(p);
|
|
|
|
if (likely(cpu == this_cpu)) {
|
|
if (!(clone_flags & CLONE_VM)) {
|
|
/*
|
|
* The VM isn't cloned, so we're in a good position to
|
|
* do child-runs-first in anticipation of an exec. This
|
|
* usually avoids a lot of COW overhead.
|
|
*/
|
|
if (unlikely(!current->array))
|
|
__activate_task(p, rq);
|
|
else {
|
|
p->prio = current->prio;
|
|
p->normal_prio = current->normal_prio;
|
|
list_add_tail(&p->run_list, ¤t->run_list);
|
|
p->array = current->array;
|
|
p->array->nr_active++;
|
|
inc_nr_running(p, rq);
|
|
}
|
|
set_need_resched();
|
|
} else
|
|
/* Run child last */
|
|
__activate_task(p, rq);
|
|
/*
|
|
* We skip the following code due to cpu == this_cpu
|
|
*
|
|
* task_rq_unlock(rq, &flags);
|
|
* this_rq = task_rq_lock(current, &flags);
|
|
*/
|
|
this_rq = rq;
|
|
} else {
|
|
this_rq = cpu_rq(this_cpu);
|
|
|
|
/*
|
|
* Not the local CPU - must adjust timestamp. This should
|
|
* get optimised away in the !CONFIG_SMP case.
|
|
*/
|
|
p->timestamp = (p->timestamp - this_rq->most_recent_timestamp)
|
|
+ rq->most_recent_timestamp;
|
|
__activate_task(p, rq);
|
|
if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
|
|
/*
|
|
* Parent and child are on different CPUs, now get the
|
|
* parent runqueue to update the parent's ->sleep_avg:
|
|
*/
|
|
task_rq_unlock(rq, &flags);
|
|
this_rq = task_rq_lock(current, &flags);
|
|
}
|
|
current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
|
|
PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
|
|
task_rq_unlock(this_rq, &flags);
|
|
}
|
|
|
|
/*
|
|
* Potentially available exiting-child timeslices are
|
|
* retrieved here - this way the parent does not get
|
|
* penalized for creating too many threads.
|
|
*
|
|
* (this cannot be used to 'generate' timeslices
|
|
* artificially, because any timeslice recovered here
|
|
* was given away by the parent in the first place.)
|
|
*/
|
|
void fastcall sched_exit(struct task_struct *p)
|
|
{
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
/*
|
|
* If the child was a (relative-) CPU hog then decrease
|
|
* the sleep_avg of the parent as well.
|
|
*/
|
|
rq = task_rq_lock(p->parent, &flags);
|
|
if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) {
|
|
p->parent->time_slice += p->time_slice;
|
|
if (unlikely(p->parent->time_slice > task_timeslice(p)))
|
|
p->parent->time_slice = task_timeslice(p);
|
|
}
|
|
if (p->sleep_avg < p->parent->sleep_avg)
|
|
p->parent->sleep_avg = p->parent->sleep_avg /
|
|
(EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
|
|
(EXIT_WEIGHT + 1);
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/**
|
|
* prepare_task_switch - prepare to switch tasks
|
|
* @rq: the runqueue preparing to switch
|
|
* @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 *next)
|
|
{
|
|
prepare_lock_switch(rq, next);
|
|
prepare_arch_switch(next);
|
|
}
|
|
|
|
/**
|
|
* finish_task_switch - clean up after a task-switch
|
|
* @rq: runqueue associated with 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.)
|
|
*/
|
|
static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
struct mm_struct *mm = rq->prev_mm;
|
|
long prev_state;
|
|
|
|
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.
|
|
* The test for TASK_DEAD must occur while the runqueue locks are
|
|
* still held, otherwise prev could be scheduled on another cpu, die
|
|
* there before we look at prev->state, and then the reference would
|
|
* be dropped twice.
|
|
* Manfred Spraul <manfred@colorfullife.com>
|
|
*/
|
|
prev_state = prev->state;
|
|
finish_arch_switch(prev);
|
|
finish_lock_switch(rq, prev);
|
|
if (mm)
|
|
mmdrop(mm);
|
|
if (unlikely(prev_state == TASK_DEAD)) {
|
|
/*
|
|
* Remove function-return probe instances associated with this
|
|
* task and put them back on the free list.
|
|
*/
|
|
kprobe_flush_task(prev);
|
|
put_task_struct(prev);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* schedule_tail - first thing a freshly forked thread must call.
|
|
* @prev: the thread we just switched away from.
|
|
*/
|
|
asmlinkage void schedule_tail(struct task_struct *prev)
|
|
__releases(rq->lock)
|
|
{
|
|
struct rq *rq = this_rq();
|
|
|
|
finish_task_switch(rq, prev);
|
|
#ifdef __ARCH_WANT_UNLOCKED_CTXSW
|
|
/* In this case, finish_task_switch does not reenable preemption */
|
|
preempt_enable();
|
|
#endif
|
|
if (current->set_child_tid)
|
|
put_user(current->pid, current->set_child_tid);
|
|
}
|
|
|
|
/*
|
|
* context_switch - switch to the new MM and the new
|
|
* thread's register state.
|
|
*/
|
|
static inline struct task_struct *
|
|
context_switch(struct rq *rq, struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
struct mm_struct *mm = next->mm;
|
|
struct mm_struct *oldmm = prev->active_mm;
|
|
|
|
/*
|
|
* 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_enter_lazy_cpu_mode();
|
|
|
|
if (!mm) {
|
|
next->active_mm = oldmm;
|
|
atomic_inc(&oldmm->mm_count);
|
|
enter_lazy_tlb(oldmm, next);
|
|
} else
|
|
switch_mm(oldmm, mm, next);
|
|
|
|
if (!prev->mm) {
|
|
prev->active_mm = NULL;
|
|
WARN_ON(rq->prev_mm);
|
|
rq->prev_mm = oldmm;
|
|
}
|
|
/*
|
|
* 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:
|
|
*/
|
|
#ifndef __ARCH_WANT_UNLOCKED_CTXSW
|
|
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
|
|
#endif
|
|
|
|
/* Here we just switch the register state and the stack. */
|
|
switch_to(prev, next, prev);
|
|
|
|
return prev;
|
|
}
|
|
|
|
/*
|
|
* nr_running, nr_uninterruptible and nr_context_switches:
|
|
*
|
|
* externally visible scheduler statistics: current number of runnable
|
|
* threads, current number of uninterruptible-sleeping 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;
|
|
}
|
|
|
|
unsigned long nr_uninterruptible(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_possible_cpu(i)
|
|
sum += cpu_rq(i)->nr_uninterruptible;
|
|
|
|
/*
|
|
* Since we read the counters lockless, it might be slightly
|
|
* inaccurate. Do not allow it to go below zero though:
|
|
*/
|
|
if (unlikely((long)sum < 0))
|
|
sum = 0;
|
|
|
|
return sum;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
unsigned long nr_iowait(void)
|
|
{
|
|
unsigned long i, sum = 0;
|
|
|
|
for_each_possible_cpu(i)
|
|
sum += atomic_read(&cpu_rq(i)->nr_iowait);
|
|
|
|
return sum;
|
|
}
|
|
|
|
unsigned long nr_active(void)
|
|
{
|
|
unsigned long i, running = 0, uninterruptible = 0;
|
|
|
|
for_each_online_cpu(i) {
|
|
running += cpu_rq(i)->nr_running;
|
|
uninterruptible += cpu_rq(i)->nr_uninterruptible;
|
|
}
|
|
|
|
if (unlikely((long)uninterruptible < 0))
|
|
uninterruptible = 0;
|
|
|
|
return running + uninterruptible;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/*
|
|
* Is this task likely cache-hot:
|
|
*/
|
|
static inline int
|
|
task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
|
|
{
|
|
return (long long)(now - p->last_ran) < (long long)sd->cache_hot_time;
|
|
}
|
|
|
|
/*
|
|
* double_rq_lock - safely lock two runqueues
|
|
*
|
|
* Note this does not disable interrupts like task_rq_lock,
|
|
* you need to do so manually before calling.
|
|
*/
|
|
static void double_rq_lock(struct rq *rq1, struct rq *rq2)
|
|
__acquires(rq1->lock)
|
|
__acquires(rq2->lock)
|
|
{
|
|
BUG_ON(!irqs_disabled());
|
|
if (rq1 == rq2) {
|
|
spin_lock(&rq1->lock);
|
|
__acquire(rq2->lock); /* Fake it out ;) */
|
|
} else {
|
|
if (rq1 < rq2) {
|
|
spin_lock(&rq1->lock);
|
|
spin_lock(&rq2->lock);
|
|
} else {
|
|
spin_lock(&rq2->lock);
|
|
spin_lock(&rq1->lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* double_rq_unlock - safely unlock two runqueues
|
|
*
|
|
* Note this does not restore interrupts like task_rq_unlock,
|
|
* you need to do so manually after calling.
|
|
*/
|
|
static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
|
|
__releases(rq1->lock)
|
|
__releases(rq2->lock)
|
|
{
|
|
spin_unlock(&rq1->lock);
|
|
if (rq1 != rq2)
|
|
spin_unlock(&rq2->lock);
|
|
else
|
|
__release(rq2->lock);
|
|
}
|
|
|
|
/*
|
|
* double_lock_balance - lock the busiest runqueue, this_rq is locked already.
|
|
*/
|
|
static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
|
|
__releases(this_rq->lock)
|
|
__acquires(busiest->lock)
|
|
__acquires(this_rq->lock)
|
|
{
|
|
if (unlikely(!irqs_disabled())) {
|
|
/* printk() doesn't work good under rq->lock */
|
|
spin_unlock(&this_rq->lock);
|
|
BUG_ON(1);
|
|
}
|
|
if (unlikely(!spin_trylock(&busiest->lock))) {
|
|
if (busiest < this_rq) {
|
|
spin_unlock(&this_rq->lock);
|
|
spin_lock(&busiest->lock);
|
|
spin_lock(&this_rq->lock);
|
|
} else
|
|
spin_lock(&busiest->lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If dest_cpu is allowed for this process, migrate the task to it.
|
|
* This is accomplished by forcing the cpu_allowed mask to only
|
|
* allow dest_cpu, which will force the cpu onto dest_cpu. Then
|
|
* the cpu_allowed mask is restored.
|
|
*/
|
|
static void sched_migrate_task(struct task_struct *p, int dest_cpu)
|
|
{
|
|
struct migration_req req;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
if (!cpu_isset(dest_cpu, p->cpus_allowed)
|
|
|| unlikely(cpu_is_offline(dest_cpu)))
|
|
goto out;
|
|
|
|
/* force the process onto the specified CPU */
|
|
if (migrate_task(p, dest_cpu, &req)) {
|
|
/* Need to wait for migration thread (might exit: take ref). */
|
|
struct task_struct *mt = rq->migration_thread;
|
|
|
|
get_task_struct(mt);
|
|
task_rq_unlock(rq, &flags);
|
|
wake_up_process(mt);
|
|
put_task_struct(mt);
|
|
wait_for_completion(&req.done);
|
|
|
|
return;
|
|
}
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
int new_cpu, this_cpu = get_cpu();
|
|
new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
|
|
put_cpu();
|
|
if (new_cpu != this_cpu)
|
|
sched_migrate_task(current, new_cpu);
|
|
}
|
|
|
|
/*
|
|
* pull_task - move a task from a remote runqueue to the local runqueue.
|
|
* Both runqueues must be locked.
|
|
*/
|
|
static void pull_task(struct rq *src_rq, struct prio_array *src_array,
|
|
struct task_struct *p, struct rq *this_rq,
|
|
struct prio_array *this_array, int this_cpu)
|
|
{
|
|
dequeue_task(p, src_array);
|
|
dec_nr_running(p, src_rq);
|
|
set_task_cpu(p, this_cpu);
|
|
inc_nr_running(p, this_rq);
|
|
enqueue_task(p, this_array);
|
|
p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
|
|
+ this_rq->most_recent_timestamp;
|
|
/*
|
|
* Note that idle threads have a prio of MAX_PRIO, for this test
|
|
* to be always true for them.
|
|
*/
|
|
if (TASK_PREEMPTS_CURR(p, this_rq))
|
|
resched_task(this_rq->curr);
|
|
}
|
|
|
|
/*
|
|
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
|
|
*/
|
|
static
|
|
int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
|
|
struct sched_domain *sd, enum idle_type idle,
|
|
int *all_pinned)
|
|
{
|
|
/*
|
|
* We do not migrate tasks that are:
|
|
* 1) running (obviously), or
|
|
* 2) cannot be migrated to this CPU due to cpus_allowed, or
|
|
* 3) are cache-hot on their current CPU.
|
|
*/
|
|
if (!cpu_isset(this_cpu, p->cpus_allowed))
|
|
return 0;
|
|
*all_pinned = 0;
|
|
|
|
if (task_running(rq, p))
|
|
return 0;
|
|
|
|
/*
|
|
* Aggressive migration if:
|
|
* 1) task is cache cold, or
|
|
* 2) too many balance attempts have failed.
|
|
*/
|
|
|
|
if (sd->nr_balance_failed > sd->cache_nice_tries) {
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (task_hot(p, rq->most_recent_timestamp, sd))
|
|
schedstat_inc(sd, lb_hot_gained[idle]);
|
|
#endif
|
|
return 1;
|
|
}
|
|
|
|
if (task_hot(p, rq->most_recent_timestamp, sd))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
#define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
|
|
|
|
/*
|
|
* move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
|
|
* load from busiest to this_rq, as part of a balancing operation within
|
|
* "domain". Returns the number of tasks moved.
|
|
*
|
|
* Called with both runqueues locked.
|
|
*/
|
|
static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_nr_move, unsigned long max_load_move,
|
|
struct sched_domain *sd, enum idle_type idle,
|
|
int *all_pinned)
|
|
{
|
|
int idx, pulled = 0, pinned = 0, this_best_prio, best_prio,
|
|
best_prio_seen, skip_for_load;
|
|
struct prio_array *array, *dst_array;
|
|
struct list_head *head, *curr;
|
|
struct task_struct *tmp;
|
|
long rem_load_move;
|
|
|
|
if (max_nr_move == 0 || max_load_move == 0)
|
|
goto out;
|
|
|
|
rem_load_move = max_load_move;
|
|
pinned = 1;
|
|
this_best_prio = rq_best_prio(this_rq);
|
|
best_prio = rq_best_prio(busiest);
|
|
/*
|
|
* Enable handling of the case where there is more than one task
|
|
* with the best priority. If the current running task is one
|
|
* of those with prio==best_prio we know it won't be moved
|
|
* and therefore it's safe to override the skip (based on load) of
|
|
* any task we find with that prio.
|
|
*/
|
|
best_prio_seen = best_prio == busiest->curr->prio;
|
|
|
|
/*
|
|
* We first consider expired tasks. Those will likely not be
|
|
* executed in the near future, and they are most likely to
|
|
* be cache-cold, thus switching CPUs has the least effect
|
|
* on them.
|
|
*/
|
|
if (busiest->expired->nr_active) {
|
|
array = busiest->expired;
|
|
dst_array = this_rq->expired;
|
|
} else {
|
|
array = busiest->active;
|
|
dst_array = this_rq->active;
|
|
}
|
|
|
|
new_array:
|
|
/* Start searching at priority 0: */
|
|
idx = 0;
|
|
skip_bitmap:
|
|
if (!idx)
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
else
|
|
idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
|
|
if (idx >= MAX_PRIO) {
|
|
if (array == busiest->expired && busiest->active->nr_active) {
|
|
array = busiest->active;
|
|
dst_array = this_rq->active;
|
|
goto new_array;
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
head = array->queue + idx;
|
|
curr = head->prev;
|
|
skip_queue:
|
|
tmp = list_entry(curr, struct task_struct, run_list);
|
|
|
|
curr = curr->prev;
|
|
|
|
/*
|
|
* To help distribute high priority tasks accross CPUs we don't
|
|
* skip a task if it will be the highest priority task (i.e. smallest
|
|
* prio value) on its new queue regardless of its load weight
|
|
*/
|
|
skip_for_load = tmp->load_weight > rem_load_move;
|
|
if (skip_for_load && idx < this_best_prio)
|
|
skip_for_load = !best_prio_seen && idx == best_prio;
|
|
if (skip_for_load ||
|
|
!can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
|
|
|
|
best_prio_seen |= idx == best_prio;
|
|
if (curr != head)
|
|
goto skip_queue;
|
|
idx++;
|
|
goto skip_bitmap;
|
|
}
|
|
|
|
pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
|
|
pulled++;
|
|
rem_load_move -= tmp->load_weight;
|
|
|
|
/*
|
|
* We only want to steal up to the prescribed number of tasks
|
|
* and the prescribed amount of weighted load.
|
|
*/
|
|
if (pulled < max_nr_move && rem_load_move > 0) {
|
|
if (idx < this_best_prio)
|
|
this_best_prio = idx;
|
|
if (curr != head)
|
|
goto skip_queue;
|
|
idx++;
|
|
goto skip_bitmap;
|
|
}
|
|
out:
|
|
/*
|
|
* Right now, this is the only place pull_task() is called,
|
|
* so we can safely collect pull_task() stats here rather than
|
|
* inside pull_task().
|
|
*/
|
|
schedstat_add(sd, lb_gained[idle], pulled);
|
|
|
|
if (all_pinned)
|
|
*all_pinned = pinned;
|
|
return pulled;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_group finds and returns the busiest CPU group within the
|
|
* domain. It calculates and returns the amount of weighted load which
|
|
* should be moved to restore balance via the imbalance parameter.
|
|
*/
|
|
static struct sched_group *
|
|
find_busiest_group(struct sched_domain *sd, int this_cpu,
|
|
unsigned long *imbalance, enum idle_type idle, int *sd_idle,
|
|
cpumask_t *cpus, int *balance)
|
|
{
|
|
struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
|
|
unsigned long max_load, avg_load, total_load, this_load, total_pwr;
|
|
unsigned long max_pull;
|
|
unsigned long busiest_load_per_task, busiest_nr_running;
|
|
unsigned long this_load_per_task, this_nr_running;
|
|
int load_idx;
|
|
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
|
|
int power_savings_balance = 1;
|
|
unsigned long leader_nr_running = 0, min_load_per_task = 0;
|
|
unsigned long min_nr_running = ULONG_MAX;
|
|
struct sched_group *group_min = NULL, *group_leader = NULL;
|
|
#endif
|
|
|
|
max_load = this_load = total_load = total_pwr = 0;
|
|
busiest_load_per_task = busiest_nr_running = 0;
|
|
this_load_per_task = this_nr_running = 0;
|
|
if (idle == NOT_IDLE)
|
|
load_idx = sd->busy_idx;
|
|
else if (idle == NEWLY_IDLE)
|
|
load_idx = sd->newidle_idx;
|
|
else
|
|
load_idx = sd->idle_idx;
|
|
|
|
do {
|
|
unsigned long load, group_capacity;
|
|
int local_group;
|
|
int i;
|
|
unsigned int balance_cpu = -1, first_idle_cpu = 0;
|
|
unsigned long sum_nr_running, sum_weighted_load;
|
|
|
|
local_group = cpu_isset(this_cpu, group->cpumask);
|
|
|
|
if (local_group)
|
|
balance_cpu = first_cpu(group->cpumask);
|
|
|
|
/* Tally up the load of all CPUs in the group */
|
|
sum_weighted_load = sum_nr_running = avg_load = 0;
|
|
|
|
for_each_cpu_mask(i, group->cpumask) {
|
|
struct rq *rq;
|
|
|
|
if (!cpu_isset(i, *cpus))
|
|
continue;
|
|
|
|
rq = cpu_rq(i);
|
|
|
|
if (*sd_idle && !idle_cpu(i))
|
|
*sd_idle = 0;
|
|
|
|
/* Bias balancing toward cpus of our domain */
|
|
if (local_group) {
|
|
if (idle_cpu(i) && !first_idle_cpu) {
|
|
first_idle_cpu = 1;
|
|
balance_cpu = i;
|
|
}
|
|
|
|
load = target_load(i, load_idx);
|
|
} else
|
|
load = source_load(i, load_idx);
|
|
|
|
avg_load += load;
|
|
sum_nr_running += rq->nr_running;
|
|
sum_weighted_load += rq->raw_weighted_load;
|
|
}
|
|
|
|
/*
|
|
* First idle cpu or the first cpu(busiest) in this sched group
|
|
* is eligible for doing load balancing at this and above
|
|
* domains.
|
|
*/
|
|
if (local_group && balance_cpu != this_cpu && balance) {
|
|
*balance = 0;
|
|
goto ret;
|
|
}
|
|
|
|
total_load += avg_load;
|
|
total_pwr += group->cpu_power;
|
|
|
|
/* Adjust by relative CPU power of the group */
|
|
avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
|
|
|
|
group_capacity = group->cpu_power / SCHED_LOAD_SCALE;
|
|
|
|
if (local_group) {
|
|
this_load = avg_load;
|
|
this = group;
|
|
this_nr_running = sum_nr_running;
|
|
this_load_per_task = sum_weighted_load;
|
|
} else if (avg_load > max_load &&
|
|
sum_nr_running > group_capacity) {
|
|
max_load = avg_load;
|
|
busiest = group;
|
|
busiest_nr_running = sum_nr_running;
|
|
busiest_load_per_task = sum_weighted_load;
|
|
}
|
|
|
|
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
|
|
/*
|
|
* Busy processors will not participate in power savings
|
|
* balance.
|
|
*/
|
|
if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
|
|
goto group_next;
|
|
|
|
/*
|
|
* If the local group is idle or completely loaded
|
|
* no need to do power savings balance at this domain
|
|
*/
|
|
if (local_group && (this_nr_running >= group_capacity ||
|
|
!this_nr_running))
|
|
power_savings_balance = 0;
|
|
|
|
/*
|
|
* If a group is already running at full capacity or idle,
|
|
* don't include that group in power savings calculations
|
|
*/
|
|
if (!power_savings_balance || sum_nr_running >= group_capacity
|
|
|| !sum_nr_running)
|
|
goto group_next;
|
|
|
|
/*
|
|
* Calculate the group which has the least non-idle load.
|
|
* This is the group from where we need to pick up the load
|
|
* for saving power
|
|
*/
|
|
if ((sum_nr_running < min_nr_running) ||
|
|
(sum_nr_running == min_nr_running &&
|
|
first_cpu(group->cpumask) <
|
|
first_cpu(group_min->cpumask))) {
|
|
group_min = group;
|
|
min_nr_running = sum_nr_running;
|
|
min_load_per_task = sum_weighted_load /
|
|
sum_nr_running;
|
|
}
|
|
|
|
/*
|
|
* Calculate the group which is almost near its
|
|
* capacity but still has some space to pick up some load
|
|
* from other group and save more power
|
|
*/
|
|
if (sum_nr_running <= group_capacity - 1) {
|
|
if (sum_nr_running > leader_nr_running ||
|
|
(sum_nr_running == leader_nr_running &&
|
|
first_cpu(group->cpumask) >
|
|
first_cpu(group_leader->cpumask))) {
|
|
group_leader = group;
|
|
leader_nr_running = sum_nr_running;
|
|
}
|
|
}
|
|
group_next:
|
|
#endif
|
|
group = group->next;
|
|
} while (group != sd->groups);
|
|
|
|
if (!busiest || this_load >= max_load || busiest_nr_running == 0)
|
|
goto out_balanced;
|
|
|
|
avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
|
|
|
|
if (this_load >= avg_load ||
|
|
100*max_load <= sd->imbalance_pct*this_load)
|
|
goto out_balanced;
|
|
|
|
busiest_load_per_task /= busiest_nr_running;
|
|
/*
|
|
* We're trying to get all the cpus to the average_load, so we don't
|
|
* want to push ourselves above the average load, nor do we wish to
|
|
* reduce the max loaded cpu below the average load, as either of these
|
|
* actions would just result in more rebalancing later, and ping-pong
|
|
* tasks around. Thus we look for the minimum possible imbalance.
|
|
* Negative imbalances (*we* are more loaded than anyone else) will
|
|
* be counted as no imbalance for these purposes -- we can't fix that
|
|
* by pulling tasks to us. Be careful of negative numbers as they'll
|
|
* appear as very large values with unsigned longs.
|
|
*/
|
|
if (max_load <= busiest_load_per_task)
|
|
goto out_balanced;
|
|
|
|
/*
|
|
* In the presence of smp nice balancing, certain scenarios can have
|
|
* max load less than avg load(as we skip the groups at or below
|
|
* its cpu_power, while calculating max_load..)
|
|
*/
|
|
if (max_load < avg_load) {
|
|
*imbalance = 0;
|
|
goto small_imbalance;
|
|
}
|
|
|
|
/* Don't want to pull so many tasks that a group would go idle */
|
|
max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
|
|
|
|
/* How much load to actually move to equalise the imbalance */
|
|
*imbalance = min(max_pull * busiest->cpu_power,
|
|
(avg_load - this_load) * this->cpu_power)
|
|
/ SCHED_LOAD_SCALE;
|
|
|
|
/*
|
|
* if *imbalance is less than the average load per runnable task
|
|
* there is no gaurantee that any tasks will be moved so we'll have
|
|
* a think about bumping its value to force at least one task to be
|
|
* moved
|
|
*/
|
|
if (*imbalance < busiest_load_per_task) {
|
|
unsigned long tmp, pwr_now, pwr_move;
|
|
unsigned int imbn;
|
|
|
|
small_imbalance:
|
|
pwr_move = pwr_now = 0;
|
|
imbn = 2;
|
|
if (this_nr_running) {
|
|
this_load_per_task /= this_nr_running;
|
|
if (busiest_load_per_task > this_load_per_task)
|
|
imbn = 1;
|
|
} else
|
|
this_load_per_task = SCHED_LOAD_SCALE;
|
|
|
|
if (max_load - this_load >= busiest_load_per_task * imbn) {
|
|
*imbalance = busiest_load_per_task;
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* OK, we don't have enough imbalance to justify moving tasks,
|
|
* however we may be able to increase total CPU power used by
|
|
* moving them.
|
|
*/
|
|
|
|
pwr_now += busiest->cpu_power *
|
|
min(busiest_load_per_task, max_load);
|
|
pwr_now += this->cpu_power *
|
|
min(this_load_per_task, this_load);
|
|
pwr_now /= SCHED_LOAD_SCALE;
|
|
|
|
/* Amount of load we'd subtract */
|
|
tmp = busiest_load_per_task * SCHED_LOAD_SCALE /
|
|
busiest->cpu_power;
|
|
if (max_load > tmp)
|
|
pwr_move += busiest->cpu_power *
|
|
min(busiest_load_per_task, max_load - tmp);
|
|
|
|
/* Amount of load we'd add */
|
|
if (max_load * busiest->cpu_power <
|
|
busiest_load_per_task * SCHED_LOAD_SCALE)
|
|
tmp = max_load * busiest->cpu_power / this->cpu_power;
|
|
else
|
|
tmp = busiest_load_per_task * SCHED_LOAD_SCALE /
|
|
this->cpu_power;
|
|
pwr_move += this->cpu_power *
|
|
min(this_load_per_task, this_load + tmp);
|
|
pwr_move /= SCHED_LOAD_SCALE;
|
|
|
|
/* Move if we gain throughput */
|
|
if (pwr_move <= pwr_now)
|
|
goto out_balanced;
|
|
|
|
*imbalance = busiest_load_per_task;
|
|
}
|
|
|
|
return busiest;
|
|
|
|
out_balanced:
|
|
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
|
|
if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
|
|
goto ret;
|
|
|
|
if (this == group_leader && group_leader != group_min) {
|
|
*imbalance = min_load_per_task;
|
|
return group_min;
|
|
}
|
|
#endif
|
|
ret:
|
|
*imbalance = 0;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_queue - find the busiest runqueue among the cpus in group.
|
|
*/
|
|
static struct rq *
|
|
find_busiest_queue(struct sched_group *group, enum idle_type idle,
|
|
unsigned long imbalance, cpumask_t *cpus)
|
|
{
|
|
struct rq *busiest = NULL, *rq;
|
|
unsigned long max_load = 0;
|
|
int i;
|
|
|
|
for_each_cpu_mask(i, group->cpumask) {
|
|
|
|
if (!cpu_isset(i, *cpus))
|
|
continue;
|
|
|
|
rq = cpu_rq(i);
|
|
|
|
if (rq->nr_running == 1 && rq->raw_weighted_load > imbalance)
|
|
continue;
|
|
|
|
if (rq->raw_weighted_load > max_load) {
|
|
max_load = rq->raw_weighted_load;
|
|
busiest = rq;
|
|
}
|
|
}
|
|
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
|
|
* so long as it is large enough.
|
|
*/
|
|
#define MAX_PINNED_INTERVAL 512
|
|
|
|
static inline unsigned long minus_1_or_zero(unsigned long n)
|
|
{
|
|
return n > 0 ? n - 1 : 0;
|
|
}
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*/
|
|
static int load_balance(int this_cpu, struct rq *this_rq,
|
|
struct sched_domain *sd, enum idle_type idle,
|
|
int *balance)
|
|
{
|
|
int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
|
|
struct sched_group *group;
|
|
unsigned long imbalance;
|
|
struct rq *busiest;
|
|
cpumask_t cpus = CPU_MASK_ALL;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* When power savings policy is enabled for the parent domain, idle
|
|
* sibling can pick up load irrespective of busy siblings. In this case,
|
|
* let the state of idle sibling percolate up as IDLE, instead of
|
|
* portraying it as NOT_IDLE.
|
|
*/
|
|
if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
sd_idle = 1;
|
|
|
|
schedstat_inc(sd, lb_cnt[idle]);
|
|
|
|
redo:
|
|
group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
|
|
&cpus, balance);
|
|
|
|
if (*balance == 0)
|
|
goto out_balanced;
|
|
|
|
if (!group) {
|
|
schedstat_inc(sd, lb_nobusyg[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
busiest = find_busiest_queue(group, idle, imbalance, &cpus);
|
|
if (!busiest) {
|
|
schedstat_inc(sd, lb_nobusyq[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
BUG_ON(busiest == this_rq);
|
|
|
|
schedstat_add(sd, lb_imbalance[idle], imbalance);
|
|
|
|
nr_moved = 0;
|
|
if (busiest->nr_running > 1) {
|
|
/*
|
|
* Attempt to move tasks. If find_busiest_group has found
|
|
* an imbalance but busiest->nr_running <= 1, the group is
|
|
* still unbalanced. nr_moved simply stays zero, so it is
|
|
* correctly treated as an imbalance.
|
|
*/
|
|
local_irq_save(flags);
|
|
double_rq_lock(this_rq, busiest);
|
|
nr_moved = move_tasks(this_rq, this_cpu, busiest,
|
|
minus_1_or_zero(busiest->nr_running),
|
|
imbalance, sd, idle, &all_pinned);
|
|
double_rq_unlock(this_rq, busiest);
|
|
local_irq_restore(flags);
|
|
|
|
/* All tasks on this runqueue were pinned by CPU affinity */
|
|
if (unlikely(all_pinned)) {
|
|
cpu_clear(cpu_of(busiest), cpus);
|
|
if (!cpus_empty(cpus))
|
|
goto redo;
|
|
goto out_balanced;
|
|
}
|
|
}
|
|
|
|
if (!nr_moved) {
|
|
schedstat_inc(sd, lb_failed[idle]);
|
|
sd->nr_balance_failed++;
|
|
|
|
if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
|
|
|
|
spin_lock_irqsave(&busiest->lock, flags);
|
|
|
|
/* don't kick the migration_thread, if the curr
|
|
* task on busiest cpu can't be moved to this_cpu
|
|
*/
|
|
if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
|
|
spin_unlock_irqrestore(&busiest->lock, flags);
|
|
all_pinned = 1;
|
|
goto out_one_pinned;
|
|
}
|
|
|
|
if (!busiest->active_balance) {
|
|
busiest->active_balance = 1;
|
|
busiest->push_cpu = this_cpu;
|
|
active_balance = 1;
|
|
}
|
|
spin_unlock_irqrestore(&busiest->lock, flags);
|
|
if (active_balance)
|
|
wake_up_process(busiest->migration_thread);
|
|
|
|
/*
|
|
* We've kicked active balancing, reset the failure
|
|
* counter.
|
|
*/
|
|
sd->nr_balance_failed = sd->cache_nice_tries+1;
|
|
}
|
|
} else
|
|
sd->nr_balance_failed = 0;
|
|
|
|
if (likely(!active_balance)) {
|
|
/* We were unbalanced, so reset the balancing interval */
|
|
sd->balance_interval = sd->min_interval;
|
|
} else {
|
|
/*
|
|
* If we've begun active balancing, start to back off. This
|
|
* case may not be covered by the all_pinned logic if there
|
|
* is only 1 task on the busy runqueue (because we don't call
|
|
* move_tasks).
|
|
*/
|
|
if (sd->balance_interval < sd->max_interval)
|
|
sd->balance_interval *= 2;
|
|
}
|
|
|
|
if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
return -1;
|
|
return nr_moved;
|
|
|
|
out_balanced:
|
|
schedstat_inc(sd, lb_balanced[idle]);
|
|
|
|
sd->nr_balance_failed = 0;
|
|
|
|
out_one_pinned:
|
|
/* tune up the balancing interval */
|
|
if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
|
|
(sd->balance_interval < sd->max_interval))
|
|
sd->balance_interval *= 2;
|
|
|
|
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
return -1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*
|
|
* Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
|
|
* this_rq is locked.
|
|
*/
|
|
static int
|
|
load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
|
|
{
|
|
struct sched_group *group;
|
|
struct rq *busiest = NULL;
|
|
unsigned long imbalance;
|
|
int nr_moved = 0;
|
|
int sd_idle = 0;
|
|
cpumask_t cpus = CPU_MASK_ALL;
|
|
|
|
/*
|
|
* When power savings policy is enabled for the parent domain, idle
|
|
* sibling can pick up load irrespective of busy siblings. In this case,
|
|
* let the state of idle sibling percolate up as IDLE, instead of
|
|
* portraying it as NOT_IDLE.
|
|
*/
|
|
if (sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
sd_idle = 1;
|
|
|
|
schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
|
|
redo:
|
|
group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE,
|
|
&sd_idle, &cpus, NULL);
|
|
if (!group) {
|
|
schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
busiest = find_busiest_queue(group, NEWLY_IDLE, imbalance,
|
|
&cpus);
|
|
if (!busiest) {
|
|
schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
BUG_ON(busiest == this_rq);
|
|
|
|
schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
|
|
|
|
nr_moved = 0;
|
|
if (busiest->nr_running > 1) {
|
|
/* Attempt to move tasks */
|
|
double_lock_balance(this_rq, busiest);
|
|
nr_moved = move_tasks(this_rq, this_cpu, busiest,
|
|
minus_1_or_zero(busiest->nr_running),
|
|
imbalance, sd, NEWLY_IDLE, NULL);
|
|
spin_unlock(&busiest->lock);
|
|
|
|
if (!nr_moved) {
|
|
cpu_clear(cpu_of(busiest), cpus);
|
|
if (!cpus_empty(cpus))
|
|
goto redo;
|
|
}
|
|
}
|
|
|
|
if (!nr_moved) {
|
|
schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
|
|
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
return -1;
|
|
} else
|
|
sd->nr_balance_failed = 0;
|
|
|
|
return nr_moved;
|
|
|
|
out_balanced:
|
|
schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
|
|
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
|
|
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
|
|
return -1;
|
|
sd->nr_balance_failed = 0;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* idle_balance is called by schedule() if this_cpu is about to become
|
|
* idle. Attempts to pull tasks from other CPUs.
|
|
*/
|
|
static void idle_balance(int this_cpu, struct rq *this_rq)
|
|
{
|
|
struct sched_domain *sd;
|
|
int pulled_task = 0;
|
|
unsigned long next_balance = jiffies + 60 * HZ;
|
|
|
|
for_each_domain(this_cpu, sd) {
|
|
if (sd->flags & SD_BALANCE_NEWIDLE) {
|
|
/* If we've pulled tasks over stop searching: */
|
|
pulled_task = load_balance_newidle(this_cpu,
|
|
this_rq, sd);
|
|
if (time_after(next_balance,
|
|
sd->last_balance + sd->balance_interval))
|
|
next_balance = sd->last_balance
|
|
+ sd->balance_interval;
|
|
if (pulled_task)
|
|
break;
|
|
}
|
|
}
|
|
if (!pulled_task)
|
|
/*
|
|
* We are going idle. next_balance may be set based on
|
|
* a busy processor. So reset next_balance.
|
|
*/
|
|
this_rq->next_balance = next_balance;
|
|
}
|
|
|
|
/*
|
|
* active_load_balance is run by migration threads. It pushes running tasks
|
|
* off the busiest CPU onto idle CPUs. It requires at least 1 task to be
|
|
* running on each physical CPU where possible, and avoids physical /
|
|
* logical imbalances.
|
|
*
|
|
* Called with busiest_rq locked.
|
|
*/
|
|
static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
|
|
{
|
|
int target_cpu = busiest_rq->push_cpu;
|
|
struct sched_domain *sd;
|
|
struct rq *target_rq;
|
|
|
|
/* Is there any task to move? */
|
|
if (busiest_rq->nr_running <= 1)
|
|
return;
|
|
|
|
target_rq = cpu_rq(target_cpu);
|
|
|
|
/*
|
|
* This condition is "impossible", if it occurs
|
|
* we need to fix it. Originally reported by
|
|
* Bjorn Helgaas on a 128-cpu setup.
|
|
*/
|
|
BUG_ON(busiest_rq == target_rq);
|
|
|
|
/* move a task from busiest_rq to target_rq */
|
|
double_lock_balance(busiest_rq, target_rq);
|
|
|
|
/* Search for an sd spanning us and the target CPU. */
|
|
for_each_domain(target_cpu, sd) {
|
|
if ((sd->flags & SD_LOAD_BALANCE) &&
|
|
cpu_isset(busiest_cpu, sd->span))
|
|
break;
|
|
}
|
|
|
|
if (likely(sd)) {
|
|
schedstat_inc(sd, alb_cnt);
|
|
|
|
if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
|
|
RTPRIO_TO_LOAD_WEIGHT(100), sd, SCHED_IDLE,
|
|
NULL))
|
|
schedstat_inc(sd, alb_pushed);
|
|
else
|
|
schedstat_inc(sd, alb_failed);
|
|
}
|
|
spin_unlock(&target_rq->lock);
|
|
}
|
|
|
|
static void update_load(struct rq *this_rq)
|
|
{
|
|
unsigned long this_load;
|
|
unsigned int i, scale;
|
|
|
|
this_load = this_rq->raw_weighted_load;
|
|
|
|
/* Update our load: */
|
|
for (i = 0, scale = 1; i < 3; i++, scale += scale) {
|
|
unsigned long old_load, new_load;
|
|
|
|
/* scale is effectively 1 << i now, and >> i divides by scale */
|
|
|
|
old_load = this_rq->cpu_load[i];
|
|
new_load = this_load;
|
|
/*
|
|
* Round up the averaging division if load is increasing. This
|
|
* prevents us from getting stuck on 9 if the load is 10, for
|
|
* example.
|
|
*/
|
|
if (new_load > old_load)
|
|
new_load += scale-1;
|
|
this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* run_rebalance_domains is triggered when needed from the scheduler tick.
|
|
*
|
|
* It checks each scheduling domain to see if it is due to be balanced,
|
|
* and initiates a balancing operation if so.
|
|
*
|
|
* Balancing parameters are set up in arch_init_sched_domains.
|
|
*/
|
|
static DEFINE_SPINLOCK(balancing);
|
|
|
|
static void run_rebalance_domains(struct softirq_action *h)
|
|
{
|
|
int this_cpu = smp_processor_id(), balance = 1;
|
|
struct rq *this_rq = cpu_rq(this_cpu);
|
|
unsigned long interval;
|
|
struct sched_domain *sd;
|
|
/*
|
|
* We are idle if there are no processes running. This
|
|
* is valid even if we are the idle process (SMT).
|
|
*/
|
|
enum idle_type idle = !this_rq->nr_running ?
|
|
SCHED_IDLE : NOT_IDLE;
|
|
/* Earliest time when we have to call run_rebalance_domains again */
|
|
unsigned long next_balance = jiffies + 60*HZ;
|
|
|
|
for_each_domain(this_cpu, sd) {
|
|
if (!(sd->flags & SD_LOAD_BALANCE))
|
|
continue;
|
|
|
|
interval = sd->balance_interval;
|
|
if (idle != SCHED_IDLE)
|
|
interval *= sd->busy_factor;
|
|
|
|
/* scale ms to jiffies */
|
|
interval = msecs_to_jiffies(interval);
|
|
if (unlikely(!interval))
|
|
interval = 1;
|
|
|
|
if (sd->flags & SD_SERIALIZE) {
|
|
if (!spin_trylock(&balancing))
|
|
goto out;
|
|
}
|
|
|
|
if (time_after_eq(jiffies, sd->last_balance + interval)) {
|
|
if (load_balance(this_cpu, this_rq, sd, idle, &balance)) {
|
|
/*
|
|
* We've pulled tasks over so either we're no
|
|
* longer idle, or one of our SMT siblings is
|
|
* not idle.
|
|
*/
|
|
idle = NOT_IDLE;
|
|
}
|
|
sd->last_balance = jiffies;
|
|
}
|
|
if (sd->flags & SD_SERIALIZE)
|
|
spin_unlock(&balancing);
|
|
out:
|
|
if (time_after(next_balance, sd->last_balance + interval))
|
|
next_balance = sd->last_balance + interval;
|
|
|
|
/*
|
|
* Stop the load balance at this level. There is another
|
|
* CPU in our sched group which is doing load balancing more
|
|
* actively.
|
|
*/
|
|
if (!balance)
|
|
break;
|
|
}
|
|
this_rq->next_balance = next_balance;
|
|
}
|
|
#else
|
|
/*
|
|
* on UP we do not need to balance between CPUs:
|
|
*/
|
|
static inline void idle_balance(int cpu, struct rq *rq)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
DEFINE_PER_CPU(struct kernel_stat, kstat);
|
|
|
|
EXPORT_PER_CPU_SYMBOL(kstat);
|
|
|
|
/*
|
|
* This is called on clock ticks and on context switches.
|
|
* Bank in p->sched_time the ns elapsed since the last tick or switch.
|
|
*/
|
|
static inline void
|
|
update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now)
|
|
{
|
|
p->sched_time += now - p->last_ran;
|
|
p->last_ran = rq->most_recent_timestamp = now;
|
|
}
|
|
|
|
/*
|
|
* Return current->sched_time plus any more ns on the sched_clock
|
|
* that have not yet been banked.
|
|
*/
|
|
unsigned long long current_sched_time(const struct task_struct *p)
|
|
{
|
|
unsigned long long ns;
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
ns = p->sched_time + sched_clock() - p->last_ran;
|
|
local_irq_restore(flags);
|
|
|
|
return ns;
|
|
}
|
|
|
|
/*
|
|
* We place interactive tasks back into the active array, if possible.
|
|
*
|
|
* To guarantee that this does not starve expired tasks we ignore the
|
|
* interactivity of a task if the first expired task had to wait more
|
|
* than a 'reasonable' amount of time. This deadline timeout is
|
|
* load-dependent, as the frequency of array switched decreases with
|
|
* increasing number of running tasks. We also ignore the interactivity
|
|
* if a better static_prio task has expired:
|
|
*/
|
|
static inline int expired_starving(struct rq *rq)
|
|
{
|
|
if (rq->curr->static_prio > rq->best_expired_prio)
|
|
return 1;
|
|
if (!STARVATION_LIMIT || !rq->expired_timestamp)
|
|
return 0;
|
|
if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Account user cpu time to a process.
|
|
* @p: the process that the cpu time gets accounted to
|
|
* @hardirq_offset: the offset to subtract from hardirq_count()
|
|
* @cputime: the cpu time spent in user space since the last update
|
|
*/
|
|
void account_user_time(struct task_struct *p, cputime_t cputime)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
cputime64_t tmp;
|
|
|
|
p->utime = cputime_add(p->utime, cputime);
|
|
|
|
/* Add user time to cpustat. */
|
|
tmp = cputime_to_cputime64(cputime);
|
|
if (TASK_NICE(p) > 0)
|
|
cpustat->nice = cputime64_add(cpustat->nice, tmp);
|
|
else
|
|
cpustat->user = cputime64_add(cpustat->user, tmp);
|
|
}
|
|
|
|
/*
|
|
* Account system cpu time to a process.
|
|
* @p: the process that the cpu time gets accounted to
|
|
* @hardirq_offset: the offset to subtract from hardirq_count()
|
|
* @cputime: the cpu time spent in kernel space since the last update
|
|
*/
|
|
void account_system_time(struct task_struct *p, int hardirq_offset,
|
|
cputime_t cputime)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
struct rq *rq = this_rq();
|
|
cputime64_t tmp;
|
|
|
|
p->stime = cputime_add(p->stime, cputime);
|
|
|
|
/* Add system time to cpustat. */
|
|
tmp = cputime_to_cputime64(cputime);
|
|
if (hardirq_count() - hardirq_offset)
|
|
cpustat->irq = cputime64_add(cpustat->irq, tmp);
|
|
else if (softirq_count())
|
|
cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
|
|
else if (p != rq->idle)
|
|
cpustat->system = cputime64_add(cpustat->system, tmp);
|
|
else if (atomic_read(&rq->nr_iowait) > 0)
|
|
cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
|
|
else
|
|
cpustat->idle = cputime64_add(cpustat->idle, tmp);
|
|
/* Account for system time used */
|
|
acct_update_integrals(p);
|
|
}
|
|
|
|
/*
|
|
* Account for involuntary wait time.
|
|
* @p: the process from which the cpu time has been stolen
|
|
* @steal: the cpu time spent in involuntary wait
|
|
*/
|
|
void account_steal_time(struct task_struct *p, cputime_t steal)
|
|
{
|
|
struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
|
|
cputime64_t tmp = cputime_to_cputime64(steal);
|
|
struct rq *rq = this_rq();
|
|
|
|
if (p == rq->idle) {
|
|
p->stime = cputime_add(p->stime, steal);
|
|
if (atomic_read(&rq->nr_iowait) > 0)
|
|
cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
|
|
else
|
|
cpustat->idle = cputime64_add(cpustat->idle, tmp);
|
|
} else
|
|
cpustat->steal = cputime64_add(cpustat->steal, tmp);
|
|
}
|
|
|
|
static void task_running_tick(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (p->array != rq->active) {
|
|
/* Task has expired but was not scheduled yet */
|
|
set_tsk_need_resched(p);
|
|
return;
|
|
}
|
|
spin_lock(&rq->lock);
|
|
/*
|
|
* The task was running during this tick - update the
|
|
* time slice counter. Note: we do not update a thread's
|
|
* priority until it either goes to sleep or uses up its
|
|
* timeslice. This makes it possible for interactive tasks
|
|
* to use up their timeslices at their highest priority levels.
|
|
*/
|
|
if (rt_task(p)) {
|
|
/*
|
|
* RR tasks need a special form of timeslice management.
|
|
* FIFO tasks have no timeslices.
|
|
*/
|
|
if ((p->policy == SCHED_RR) && !--p->time_slice) {
|
|
p->time_slice = task_timeslice(p);
|
|
p->first_time_slice = 0;
|
|
set_tsk_need_resched(p);
|
|
|
|
/* put it at the end of the queue: */
|
|
requeue_task(p, rq->active);
|
|
}
|
|
goto out_unlock;
|
|
}
|
|
if (!--p->time_slice) {
|
|
dequeue_task(p, rq->active);
|
|
set_tsk_need_resched(p);
|
|
p->prio = effective_prio(p);
|
|
p->time_slice = task_timeslice(p);
|
|
p->first_time_slice = 0;
|
|
|
|
if (!rq->expired_timestamp)
|
|
rq->expired_timestamp = jiffies;
|
|
if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
|
|
enqueue_task(p, rq->expired);
|
|
if (p->static_prio < rq->best_expired_prio)
|
|
rq->best_expired_prio = p->static_prio;
|
|
} else
|
|
enqueue_task(p, rq->active);
|
|
} else {
|
|
/*
|
|
* Prevent a too long timeslice allowing a task to monopolize
|
|
* the CPU. We do this by splitting up the timeslice into
|
|
* smaller pieces.
|
|
*
|
|
* Note: this does not mean the task's timeslices expire or
|
|
* get lost in any way, they just might be preempted by
|
|
* another task of equal priority. (one with higher
|
|
* priority would have preempted this task already.) We
|
|
* requeue this task to the end of the list on this priority
|
|
* level, which is in essence a round-robin of tasks with
|
|
* equal priority.
|
|
*
|
|
* This only applies to tasks in the interactive
|
|
* delta range with at least TIMESLICE_GRANULARITY to requeue.
|
|
*/
|
|
if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
|
|
p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
|
|
(p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
|
|
(p->array == rq->active)) {
|
|
|
|
requeue_task(p, rq->active);
|
|
set_tsk_need_resched(p);
|
|
}
|
|
}
|
|
out_unlock:
|
|
spin_unlock(&rq->lock);
|
|
}
|
|
|
|
/*
|
|
* This function gets called by the timer code, with HZ frequency.
|
|
* We call it with interrupts disabled.
|
|
*
|
|
* It also gets called by the fork code, when changing the parent's
|
|
* timeslices.
|
|
*/
|
|
void scheduler_tick(void)
|
|
{
|
|
unsigned long long now = sched_clock();
|
|
struct task_struct *p = current;
|
|
int cpu = smp_processor_id();
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
update_cpu_clock(p, rq, now);
|
|
|
|
if (p != rq->idle)
|
|
task_running_tick(rq, p);
|
|
#ifdef CONFIG_SMP
|
|
update_load(rq);
|
|
if (time_after_eq(jiffies, rq->next_balance))
|
|
raise_softirq(SCHED_SOFTIRQ);
|
|
#endif
|
|
}
|
|
|
|
#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
|
|
|
|
void fastcall add_preempt_count(int val)
|
|
{
|
|
/*
|
|
* Underflow?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
|
|
return;
|
|
preempt_count() += val;
|
|
/*
|
|
* Spinlock count overflowing soon?
|
|
*/
|
|
DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
|
|
PREEMPT_MASK - 10);
|
|
}
|
|
EXPORT_SYMBOL(add_preempt_count);
|
|
|
|
void fastcall sub_preempt_count(int val)
|
|
{
|
|
/*
|
|
* 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;
|
|
|
|
preempt_count() -= val;
|
|
}
|
|
EXPORT_SYMBOL(sub_preempt_count);
|
|
|
|
#endif
|
|
|
|
static inline int interactive_sleep(enum sleep_type sleep_type)
|
|
{
|
|
return (sleep_type == SLEEP_INTERACTIVE ||
|
|
sleep_type == SLEEP_INTERRUPTED);
|
|
}
|
|
|
|
/*
|
|
* schedule() is the main scheduler function.
|
|
*/
|
|
asmlinkage void __sched schedule(void)
|
|
{
|
|
struct task_struct *prev, *next;
|
|
struct prio_array *array;
|
|
struct list_head *queue;
|
|
unsigned long long now;
|
|
unsigned long run_time;
|
|
int cpu, idx, new_prio;
|
|
long *switch_count;
|
|
struct rq *rq;
|
|
|
|
/*
|
|
* Test if we are atomic. Since do_exit() needs to call into
|
|
* schedule() atomically, we ignore that path for now.
|
|
* Otherwise, whine if we are scheduling when we should not be.
|
|
*/
|
|
if (unlikely(in_atomic() && !current->exit_state)) {
|
|
printk(KERN_ERR "BUG: scheduling while atomic: "
|
|
"%s/0x%08x/%d\n",
|
|
current->comm, preempt_count(), current->pid);
|
|
debug_show_held_locks(current);
|
|
if (irqs_disabled())
|
|
print_irqtrace_events(current);
|
|
dump_stack();
|
|
}
|
|
profile_hit(SCHED_PROFILING, __builtin_return_address(0));
|
|
|
|
need_resched:
|
|
preempt_disable();
|
|
prev = current;
|
|
release_kernel_lock(prev);
|
|
need_resched_nonpreemptible:
|
|
rq = this_rq();
|
|
|
|
/*
|
|
* The idle thread is not allowed to schedule!
|
|
* Remove this check after it has been exercised a bit.
|
|
*/
|
|
if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
|
|
printk(KERN_ERR "bad: scheduling from the idle thread!\n");
|
|
dump_stack();
|
|
}
|
|
|
|
schedstat_inc(rq, sched_cnt);
|
|
now = sched_clock();
|
|
if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
|
|
run_time = now - prev->timestamp;
|
|
if (unlikely((long long)(now - prev->timestamp) < 0))
|
|
run_time = 0;
|
|
} else
|
|
run_time = NS_MAX_SLEEP_AVG;
|
|
|
|
/*
|
|
* Tasks charged proportionately less run_time at high sleep_avg to
|
|
* delay them losing their interactive status
|
|
*/
|
|
run_time /= (CURRENT_BONUS(prev) ? : 1);
|
|
|
|
spin_lock_irq(&rq->lock);
|
|
|
|
switch_count = &prev->nivcsw;
|
|
if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
|
|
switch_count = &prev->nvcsw;
|
|
if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
|
|
unlikely(signal_pending(prev))))
|
|
prev->state = TASK_RUNNING;
|
|
else {
|
|
if (prev->state == TASK_UNINTERRUPTIBLE)
|
|
rq->nr_uninterruptible++;
|
|
deactivate_task(prev, rq);
|
|
}
|
|
}
|
|
|
|
cpu = smp_processor_id();
|
|
if (unlikely(!rq->nr_running)) {
|
|
idle_balance(cpu, rq);
|
|
if (!rq->nr_running) {
|
|
next = rq->idle;
|
|
rq->expired_timestamp = 0;
|
|
goto switch_tasks;
|
|
}
|
|
}
|
|
|
|
array = rq->active;
|
|
if (unlikely(!array->nr_active)) {
|
|
/*
|
|
* Switch the active and expired arrays.
|
|
*/
|
|
schedstat_inc(rq, sched_switch);
|
|
rq->active = rq->expired;
|
|
rq->expired = array;
|
|
array = rq->active;
|
|
rq->expired_timestamp = 0;
|
|
rq->best_expired_prio = MAX_PRIO;
|
|
}
|
|
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
queue = array->queue + idx;
|
|
next = list_entry(queue->next, struct task_struct, run_list);
|
|
|
|
if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
|
|
unsigned long long delta = now - next->timestamp;
|
|
if (unlikely((long long)(now - next->timestamp) < 0))
|
|
delta = 0;
|
|
|
|
if (next->sleep_type == SLEEP_INTERACTIVE)
|
|
delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
|
|
|
|
array = next->array;
|
|
new_prio = recalc_task_prio(next, next->timestamp + delta);
|
|
|
|
if (unlikely(next->prio != new_prio)) {
|
|
dequeue_task(next, array);
|
|
next->prio = new_prio;
|
|
enqueue_task(next, array);
|
|
}
|
|
}
|
|
next->sleep_type = SLEEP_NORMAL;
|
|
switch_tasks:
|
|
if (next == rq->idle)
|
|
schedstat_inc(rq, sched_goidle);
|
|
prefetch(next);
|
|
prefetch_stack(next);
|
|
clear_tsk_need_resched(prev);
|
|
rcu_qsctr_inc(task_cpu(prev));
|
|
|
|
update_cpu_clock(prev, rq, now);
|
|
|
|
prev->sleep_avg -= run_time;
|
|
if ((long)prev->sleep_avg <= 0)
|
|
prev->sleep_avg = 0;
|
|
prev->timestamp = prev->last_ran = now;
|
|
|
|
sched_info_switch(prev, next);
|
|
if (likely(prev != next)) {
|
|
next->timestamp = next->last_ran = now;
|
|
rq->nr_switches++;
|
|
rq->curr = next;
|
|
++*switch_count;
|
|
|
|
prepare_task_switch(rq, next);
|
|
prev = context_switch(rq, prev, next);
|
|
barrier();
|
|
/*
|
|
* this_rq must be evaluated again because prev may have moved
|
|
* CPUs since it called schedule(), thus the 'rq' on its stack
|
|
* frame will be invalid.
|
|
*/
|
|
finish_task_switch(this_rq(), prev);
|
|
} else
|
|
spin_unlock_irq(&rq->lock);
|
|
|
|
prev = current;
|
|
if (unlikely(reacquire_kernel_lock(prev) < 0))
|
|
goto need_resched_nonpreemptible;
|
|
preempt_enable_no_resched();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
EXPORT_SYMBOL(schedule);
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
/*
|
|
* this is the entry point to schedule() from in-kernel preemption
|
|
* off of preempt_enable. Kernel preemptions off return from interrupt
|
|
* occur there and call schedule directly.
|
|
*/
|
|
asmlinkage void __sched preempt_schedule(void)
|
|
{
|
|
struct thread_info *ti = current_thread_info();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
struct task_struct *task = current;
|
|
int saved_lock_depth;
|
|
#endif
|
|
/*
|
|
* 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(ti->preempt_count || irqs_disabled()))
|
|
return;
|
|
|
|
need_resched:
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
/*
|
|
* We keep the big kernel semaphore locked, but we
|
|
* clear ->lock_depth so that schedule() doesnt
|
|
* auto-release the semaphore:
|
|
*/
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
saved_lock_depth = task->lock_depth;
|
|
task->lock_depth = -1;
|
|
#endif
|
|
schedule();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
task->lock_depth = saved_lock_depth;
|
|
#endif
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
|
|
/* we could miss a preemption opportunity between schedule and now */
|
|
barrier();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
EXPORT_SYMBOL(preempt_schedule);
|
|
|
|
/*
|
|
* 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 void __sched preempt_schedule_irq(void)
|
|
{
|
|
struct thread_info *ti = current_thread_info();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
struct task_struct *task = current;
|
|
int saved_lock_depth;
|
|
#endif
|
|
/* Catch callers which need to be fixed */
|
|
BUG_ON(ti->preempt_count || !irqs_disabled());
|
|
|
|
need_resched:
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
/*
|
|
* We keep the big kernel semaphore locked, but we
|
|
* clear ->lock_depth so that schedule() doesnt
|
|
* auto-release the semaphore:
|
|
*/
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
saved_lock_depth = task->lock_depth;
|
|
task->lock_depth = -1;
|
|
#endif
|
|
local_irq_enable();
|
|
schedule();
|
|
local_irq_disable();
|
|
#ifdef CONFIG_PREEMPT_BKL
|
|
task->lock_depth = saved_lock_depth;
|
|
#endif
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
|
|
/* we could miss a preemption opportunity between schedule and now */
|
|
barrier();
|
|
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
|
|
goto need_resched;
|
|
}
|
|
|
|
#endif /* CONFIG_PREEMPT */
|
|
|
|
int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
|
|
void *key)
|
|
{
|
|
return try_to_wake_up(curr->private, mode, sync);
|
|
}
|
|
EXPORT_SYMBOL(default_wake_function);
|
|
|
|
/*
|
|
* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
|
|
* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
|
|
* number) then we wake all the non-exclusive tasks and one exclusive task.
|
|
*
|
|
* There are circumstances in which we can try to wake a task which has already
|
|
* started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
|
|
* zero in this (rare) case, and we handle it by continuing to scan the queue.
|
|
*/
|
|
static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
|
|
int nr_exclusive, int sync, void *key)
|
|
{
|
|
struct list_head *tmp, *next;
|
|
|
|
list_for_each_safe(tmp, next, &q->task_list) {
|
|
wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
|
|
unsigned flags = curr->flags;
|
|
|
|
if (curr->func(curr, mode, sync, key) &&
|
|
(flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* __wake_up - wake up threads blocked on a waitqueue.
|
|
* @q: the waitqueue
|
|
* @mode: which threads
|
|
* @nr_exclusive: how many wake-one or wake-many threads to wake up
|
|
* @key: is directly passed to the wakeup function
|
|
*/
|
|
void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
|
|
int nr_exclusive, void *key)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__wake_up_common(q, mode, nr_exclusive, 0, key);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(__wake_up);
|
|
|
|
/*
|
|
* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
|
|
*/
|
|
void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
|
|
{
|
|
__wake_up_common(q, mode, 1, 0, NULL);
|
|
}
|
|
|
|
/**
|
|
* __wake_up_sync - wake up threads blocked on a waitqueue.
|
|
* @q: the waitqueue
|
|
* @mode: which threads
|
|
* @nr_exclusive: how many wake-one or wake-many threads to wake up
|
|
*
|
|
* The sync wakeup differs that the waker knows that it will schedule
|
|
* away soon, so while the target thread will be woken up, it will not
|
|
* be migrated to another CPU - ie. the two threads are 'synchronized'
|
|
* with each other. This can prevent needless bouncing between CPUs.
|
|
*
|
|
* On UP it can prevent extra preemption.
|
|
*/
|
|
void fastcall
|
|
__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
|
|
{
|
|
unsigned long flags;
|
|
int sync = 1;
|
|
|
|
if (unlikely(!q))
|
|
return;
|
|
|
|
if (unlikely(!nr_exclusive))
|
|
sync = 0;
|
|
|
|
spin_lock_irqsave(&q->lock, flags);
|
|
__wake_up_common(q, mode, nr_exclusive, sync, NULL);
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
|
|
|
|
void fastcall complete(struct completion *x)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&x->wait.lock, flags);
|
|
x->done++;
|
|
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
|
|
1, 0, NULL);
|
|
spin_unlock_irqrestore(&x->wait.lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(complete);
|
|
|
|
void fastcall complete_all(struct completion *x)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&x->wait.lock, flags);
|
|
x->done += UINT_MAX/2;
|
|
__wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
|
|
0, 0, NULL);
|
|
spin_unlock_irqrestore(&x->wait.lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(complete_all);
|
|
|
|
void fastcall __sched wait_for_completion(struct completion *x)
|
|
{
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
schedule();
|
|
spin_lock_irq(&x->wait.lock);
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
spin_unlock_irq(&x->wait.lock);
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion);
|
|
|
|
unsigned long fastcall __sched
|
|
wait_for_completion_timeout(struct completion *x, unsigned long timeout)
|
|
{
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
timeout = schedule_timeout(timeout);
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!timeout) {
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
return timeout;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_timeout);
|
|
|
|
int fastcall __sched wait_for_completion_interruptible(struct completion *x)
|
|
{
|
|
int ret = 0;
|
|
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
schedule();
|
|
spin_lock_irq(&x->wait.lock);
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_interruptible);
|
|
|
|
unsigned long fastcall __sched
|
|
wait_for_completion_interruptible_timeout(struct completion *x,
|
|
unsigned long timeout)
|
|
{
|
|
might_sleep();
|
|
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!x->done) {
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue_tail(&x->wait, &wait);
|
|
do {
|
|
if (signal_pending(current)) {
|
|
timeout = -ERESTARTSYS;
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
spin_unlock_irq(&x->wait.lock);
|
|
timeout = schedule_timeout(timeout);
|
|
spin_lock_irq(&x->wait.lock);
|
|
if (!timeout) {
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
goto out;
|
|
}
|
|
} while (!x->done);
|
|
__remove_wait_queue(&x->wait, &wait);
|
|
}
|
|
x->done--;
|
|
out:
|
|
spin_unlock_irq(&x->wait.lock);
|
|
return timeout;
|
|
}
|
|
EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
|
|
|
|
|
|
#define SLEEP_ON_VAR \
|
|
unsigned long flags; \
|
|
wait_queue_t wait; \
|
|
init_waitqueue_entry(&wait, current);
|
|
|
|
#define SLEEP_ON_HEAD \
|
|
spin_lock_irqsave(&q->lock,flags); \
|
|
__add_wait_queue(q, &wait); \
|
|
spin_unlock(&q->lock);
|
|
|
|
#define SLEEP_ON_TAIL \
|
|
spin_lock_irq(&q->lock); \
|
|
__remove_wait_queue(q, &wait); \
|
|
spin_unlock_irqrestore(&q->lock, flags);
|
|
|
|
void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
schedule();
|
|
SLEEP_ON_TAIL
|
|
}
|
|
EXPORT_SYMBOL(interruptible_sleep_on);
|
|
|
|
long fastcall __sched
|
|
interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
timeout = schedule_timeout(timeout);
|
|
SLEEP_ON_TAIL
|
|
|
|
return timeout;
|
|
}
|
|
EXPORT_SYMBOL(interruptible_sleep_on_timeout);
|
|
|
|
void fastcall __sched sleep_on(wait_queue_head_t *q)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_UNINTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
schedule();
|
|
SLEEP_ON_TAIL
|
|
}
|
|
EXPORT_SYMBOL(sleep_on);
|
|
|
|
long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
|
|
{
|
|
SLEEP_ON_VAR
|
|
|
|
current->state = TASK_UNINTERRUPTIBLE;
|
|
|
|
SLEEP_ON_HEAD
|
|
timeout = schedule_timeout(timeout);
|
|
SLEEP_ON_TAIL
|
|
|
|
return timeout;
|
|
}
|
|
|
|
EXPORT_SYMBOL(sleep_on_timeout);
|
|
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
|
|
/*
|
|
* rt_mutex_setprio - set the current priority of a task
|
|
* @p: task
|
|
* @prio: prio value (kernel-internal form)
|
|
*
|
|
* 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.
|
|
*/
|
|
void rt_mutex_setprio(struct task_struct *p, int prio)
|
|
{
|
|
struct prio_array *array;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
int oldprio;
|
|
|
|
BUG_ON(prio < 0 || prio > MAX_PRIO);
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
|
|
oldprio = p->prio;
|
|
array = p->array;
|
|
if (array)
|
|
dequeue_task(p, array);
|
|
p->prio = prio;
|
|
|
|
if (array) {
|
|
/*
|
|
* If changing to an RT priority then queue it
|
|
* in the active array!
|
|
*/
|
|
if (rt_task(p))
|
|
array = rq->active;
|
|
enqueue_task(p, array);
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (task_running(rq, p)) {
|
|
if (p->prio > oldprio)
|
|
resched_task(rq->curr);
|
|
} else if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
}
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
|
|
#endif
|
|
|
|
void set_user_nice(struct task_struct *p, long nice)
|
|
{
|
|
struct prio_array *array;
|
|
int old_prio, delta;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
|
|
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, &flags);
|
|
/*
|
|
* 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
|
|
* not SCHED_NORMAL/SCHED_BATCH:
|
|
*/
|
|
if (has_rt_policy(p)) {
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
goto out_unlock;
|
|
}
|
|
array = p->array;
|
|
if (array) {
|
|
dequeue_task(p, array);
|
|
dec_raw_weighted_load(rq, p);
|
|
}
|
|
|
|
p->static_prio = NICE_TO_PRIO(nice);
|
|
set_load_weight(p);
|
|
old_prio = p->prio;
|
|
p->prio = effective_prio(p);
|
|
delta = p->prio - old_prio;
|
|
|
|
if (array) {
|
|
enqueue_task(p, array);
|
|
inc_raw_weighted_load(rq, p);
|
|
/*
|
|
* If the task increased its priority or is running and
|
|
* lowered its priority, then reschedule its CPU:
|
|
*/
|
|
if (delta < 0 || (delta > 0 && task_running(rq, p)))
|
|
resched_task(rq->curr);
|
|
}
|
|
out_unlock:
|
|
task_rq_unlock(rq, &flags);
|
|
}
|
|
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 = 20 - nice;
|
|
|
|
return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
|
|
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.
|
|
*/
|
|
asmlinkage long sys_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.
|
|
*/
|
|
if (increment < -40)
|
|
increment = -40;
|
|
if (increment > 40)
|
|
increment = 40;
|
|
|
|
nice = PRIO_TO_NICE(current->static_prio) + increment;
|
|
if (nice < -20)
|
|
nice = -20;
|
|
if (nice > 19)
|
|
nice = 19;
|
|
|
|
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.
|
|
*
|
|
* This is 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;
|
|
}
|
|
|
|
/**
|
|
* task_nice - return the nice value of a given task.
|
|
* @p: the task in question.
|
|
*/
|
|
int task_nice(const struct task_struct *p)
|
|
{
|
|
return TASK_NICE(p);
|
|
}
|
|
EXPORT_SYMBOL_GPL(task_nice);
|
|
|
|
/**
|
|
* idle_cpu - is a given cpu idle currently?
|
|
* @cpu: the processor in question.
|
|
*/
|
|
int idle_cpu(int cpu)
|
|
{
|
|
return cpu_curr(cpu) == cpu_rq(cpu)->idle;
|
|
}
|
|
|
|
/**
|
|
* idle_task - return the idle task for a given cpu.
|
|
* @cpu: the processor in question.
|
|
*/
|
|
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.
|
|
*/
|
|
static inline struct task_struct *find_process_by_pid(pid_t pid)
|
|
{
|
|
return pid ? find_task_by_pid(pid) : current;
|
|
}
|
|
|
|
/* Actually do priority change: must hold rq lock. */
|
|
static void __setscheduler(struct task_struct *p, int policy, int prio)
|
|
{
|
|
BUG_ON(p->array);
|
|
|
|
p->policy = policy;
|
|
p->rt_priority = prio;
|
|
p->normal_prio = normal_prio(p);
|
|
/* we are holding p->pi_lock already */
|
|
p->prio = rt_mutex_getprio(p);
|
|
/*
|
|
* SCHED_BATCH tasks are treated as perpetual CPU hogs:
|
|
*/
|
|
if (policy == SCHED_BATCH)
|
|
p->sleep_avg = 0;
|
|
set_load_weight(p);
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* NOTE that the task may be already dead.
|
|
*/
|
|
int sched_setscheduler(struct task_struct *p, int policy,
|
|
struct sched_param *param)
|
|
{
|
|
int retval, oldprio, oldpolicy = -1;
|
|
struct prio_array *array;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
/* may grab non-irq protected spin_locks */
|
|
BUG_ON(in_interrupt());
|
|
recheck:
|
|
/* double check policy once rq lock held */
|
|
if (policy < 0)
|
|
policy = oldpolicy = p->policy;
|
|
else if (policy != SCHED_FIFO && policy != SCHED_RR &&
|
|
policy != SCHED_NORMAL && policy != SCHED_BATCH)
|
|
return -EINVAL;
|
|
/*
|
|
* Valid priorities for SCHED_FIFO and SCHED_RR are
|
|
* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
|
|
* SCHED_BATCH is 0.
|
|
*/
|
|
if (param->sched_priority < 0 ||
|
|
(p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
|
|
(!p->mm && param->sched_priority > MAX_RT_PRIO-1))
|
|
return -EINVAL;
|
|
if (is_rt_policy(policy) != (param->sched_priority != 0))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Allow unprivileged RT tasks to decrease priority:
|
|
*/
|
|
if (!capable(CAP_SYS_NICE)) {
|
|
if (is_rt_policy(policy)) {
|
|
unsigned long rlim_rtprio;
|
|
unsigned long flags;
|
|
|
|
if (!lock_task_sighand(p, &flags))
|
|
return -ESRCH;
|
|
rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
|
|
unlock_task_sighand(p, &flags);
|
|
|
|
/* can't set/change the rt policy */
|
|
if (policy != p->policy && !rlim_rtprio)
|
|
return -EPERM;
|
|
|
|
/* can't increase priority */
|
|
if (param->sched_priority > p->rt_priority &&
|
|
param->sched_priority > rlim_rtprio)
|
|
return -EPERM;
|
|
}
|
|
|
|
/* can't change other user's priorities */
|
|
if ((current->euid != p->euid) &&
|
|
(current->euid != p->uid))
|
|
return -EPERM;
|
|
}
|
|
|
|
retval = security_task_setscheduler(p, policy, param);
|
|
if (retval)
|
|
return retval;
|
|
/*
|
|
* make sure no PI-waiters arrive (or leave) while we are
|
|
* changing the priority of the task:
|
|
*/
|
|
spin_lock_irqsave(&p->pi_lock, flags);
|
|
/*
|
|
* To be able to change p->policy safely, the apropriate
|
|
* runqueue lock must be held.
|
|
*/
|
|
rq = __task_rq_lock(p);
|
|
/* recheck policy now with rq lock held */
|
|
if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
|
|
policy = oldpolicy = -1;
|
|
__task_rq_unlock(rq);
|
|
spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
goto recheck;
|
|
}
|
|
array = p->array;
|
|
if (array)
|
|
deactivate_task(p, rq);
|
|
oldprio = p->prio;
|
|
__setscheduler(p, policy, param->sched_priority);
|
|
if (array) {
|
|
__activate_task(p, rq);
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (task_running(rq, p)) {
|
|
if (p->prio > oldprio)
|
|
resched_task(rq->curr);
|
|
} else if (TASK_PREEMPTS_CURR(p, rq))
|
|
resched_task(rq->curr);
|
|
}
|
|
__task_rq_unlock(rq);
|
|
spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
|
|
rt_mutex_adjust_pi(p);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sched_setscheduler);
|
|
|
|
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 (p != NULL)
|
|
retval = sched_setscheduler(p, policy, &lparam);
|
|
rcu_read_unlock();
|
|
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
|
|
struct sched_param __user *param)
|
|
{
|
|
/* negative values for policy are not valid */
|
|
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.
|
|
*/
|
|
asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
|
|
{
|
|
return do_sched_setscheduler(pid, -1, param);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getscheduler - get the policy (scheduling class) of a thread
|
|
* @pid: the pid in question.
|
|
*/
|
|
asmlinkage long sys_sched_getscheduler(pid_t pid)
|
|
{
|
|
struct task_struct *p;
|
|
int retval = -EINVAL;
|
|
|
|
if (pid < 0)
|
|
goto out_nounlock;
|
|
|
|
retval = -ESRCH;
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
if (p) {
|
|
retval = security_task_getscheduler(p);
|
|
if (!retval)
|
|
retval = p->policy;
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
out_nounlock:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_getscheduler - get the RT priority of a thread
|
|
* @pid: the pid in question.
|
|
* @param: structure containing the RT priority.
|
|
*/
|
|
asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
|
|
{
|
|
struct sched_param lp;
|
|
struct task_struct *p;
|
|
int retval = -EINVAL;
|
|
|
|
if (!param || pid < 0)
|
|
goto out_nounlock;
|
|
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
retval = -ESRCH;
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
lp.sched_priority = p->rt_priority;
|
|
read_unlock(&tasklist_lock);
|
|
|
|
/*
|
|
* This one might sleep, we cannot do it with a spinlock held ...
|
|
*/
|
|
retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
|
|
|
|
out_nounlock:
|
|
return retval;
|
|
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
return retval;
|
|
}
|
|
|
|
long sched_setaffinity(pid_t pid, cpumask_t new_mask)
|
|
{
|
|
cpumask_t cpus_allowed;
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
lock_cpu_hotplug();
|
|
read_lock(&tasklist_lock);
|
|
|
|
p = find_process_by_pid(pid);
|
|
if (!p) {
|
|
read_unlock(&tasklist_lock);
|
|
unlock_cpu_hotplug();
|
|
return -ESRCH;
|
|
}
|
|
|
|
/*
|
|
* It is not safe to call set_cpus_allowed with the
|
|
* tasklist_lock held. We will bump the task_struct's
|
|
* usage count and then drop tasklist_lock.
|
|
*/
|
|
get_task_struct(p);
|
|
read_unlock(&tasklist_lock);
|
|
|
|
retval = -EPERM;
|
|
if ((current->euid != p->euid) && (current->euid != p->uid) &&
|
|
!capable(CAP_SYS_NICE))
|
|
goto out_unlock;
|
|
|
|
retval = security_task_setscheduler(p, 0, NULL);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
cpus_allowed = cpuset_cpus_allowed(p);
|
|
cpus_and(new_mask, new_mask, cpus_allowed);
|
|
retval = set_cpus_allowed(p, new_mask);
|
|
|
|
out_unlock:
|
|
put_task_struct(p);
|
|
unlock_cpu_hotplug();
|
|
return retval;
|
|
}
|
|
|
|
static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
|
|
cpumask_t *new_mask)
|
|
{
|
|
if (len < sizeof(cpumask_t)) {
|
|
memset(new_mask, 0, sizeof(cpumask_t));
|
|
} else if (len > sizeof(cpumask_t)) {
|
|
len = sizeof(cpumask_t);
|
|
}
|
|
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
|
|
*/
|
|
asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
|
|
unsigned long __user *user_mask_ptr)
|
|
{
|
|
cpumask_t new_mask;
|
|
int retval;
|
|
|
|
retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
|
|
if (retval)
|
|
return retval;
|
|
|
|
return sched_setaffinity(pid, new_mask);
|
|
}
|
|
|
|
/*
|
|
* Represents all cpu's present in the system
|
|
* In systems capable of hotplug, this map could dynamically grow
|
|
* as new cpu's are detected in the system via any platform specific
|
|
* method, such as ACPI for e.g.
|
|
*/
|
|
|
|
cpumask_t cpu_present_map __read_mostly;
|
|
EXPORT_SYMBOL(cpu_present_map);
|
|
|
|
#ifndef CONFIG_SMP
|
|
cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
|
|
EXPORT_SYMBOL(cpu_online_map);
|
|
|
|
cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
|
|
EXPORT_SYMBOL(cpu_possible_map);
|
|
#endif
|
|
|
|
long sched_getaffinity(pid_t pid, cpumask_t *mask)
|
|
{
|
|
struct task_struct *p;
|
|
int retval;
|
|
|
|
lock_cpu_hotplug();
|
|
read_lock(&tasklist_lock);
|
|
|
|
retval = -ESRCH;
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
cpus_and(*mask, p->cpus_allowed, cpu_online_map);
|
|
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
unlock_cpu_hotplug();
|
|
if (retval)
|
|
return retval;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
*/
|
|
asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
|
|
unsigned long __user *user_mask_ptr)
|
|
{
|
|
int ret;
|
|
cpumask_t mask;
|
|
|
|
if (len < sizeof(cpumask_t))
|
|
return -EINVAL;
|
|
|
|
ret = sched_getaffinity(pid, &mask);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
|
|
return -EFAULT;
|
|
|
|
return sizeof(cpumask_t);
|
|
}
|
|
|
|
/**
|
|
* sys_sched_yield - yield the current processor to other threads.
|
|
*
|
|
* This function yields the current CPU by moving the calling thread
|
|
* to the expired array. If there are no other threads running on this
|
|
* CPU then this function will return.
|
|
*/
|
|
asmlinkage long sys_sched_yield(void)
|
|
{
|
|
struct rq *rq = this_rq_lock();
|
|
struct prio_array *array = current->array, *target = rq->expired;
|
|
|
|
schedstat_inc(rq, yld_cnt);
|
|
/*
|
|
* We implement yielding by moving the task into the expired
|
|
* queue.
|
|
*
|
|
* (special rule: RT tasks will just roundrobin in the active
|
|
* array.)
|
|
*/
|
|
if (rt_task(current))
|
|
target = rq->active;
|
|
|
|
if (array->nr_active == 1) {
|
|
schedstat_inc(rq, yld_act_empty);
|
|
if (!rq->expired->nr_active)
|
|
schedstat_inc(rq, yld_both_empty);
|
|
} else if (!rq->expired->nr_active)
|
|
schedstat_inc(rq, yld_exp_empty);
|
|
|
|
if (array != target) {
|
|
dequeue_task(current, array);
|
|
enqueue_task(current, target);
|
|
} else
|
|
/*
|
|
* requeue_task is cheaper so perform that if possible.
|
|
*/
|
|
requeue_task(current, array);
|
|
|
|
/*
|
|
* Since we are going to call schedule() anyway, there's
|
|
* no need to preempt or enable interrupts:
|
|
*/
|
|
__release(rq->lock);
|
|
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
|
|
_raw_spin_unlock(&rq->lock);
|
|
preempt_enable_no_resched();
|
|
|
|
schedule();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __cond_resched(void)
|
|
{
|
|
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
|
|
__might_sleep(__FILE__, __LINE__);
|
|
#endif
|
|
/*
|
|
* The BKS might be reacquired before we have dropped
|
|
* PREEMPT_ACTIVE, which could trigger a second
|
|
* cond_resched() call.
|
|
*/
|
|
do {
|
|
add_preempt_count(PREEMPT_ACTIVE);
|
|
schedule();
|
|
sub_preempt_count(PREEMPT_ACTIVE);
|
|
} while (need_resched());
|
|
}
|
|
|
|
int __sched cond_resched(void)
|
|
{
|
|
if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
|
|
system_state == SYSTEM_RUNNING) {
|
|
__cond_resched();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(cond_resched);
|
|
|
|
/*
|
|
* 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_PREEMPT. 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 ret = 0;
|
|
|
|
if (need_lockbreak(lock)) {
|
|
spin_unlock(lock);
|
|
cpu_relax();
|
|
ret = 1;
|
|
spin_lock(lock);
|
|
}
|
|
if (need_resched() && system_state == SYSTEM_RUNNING) {
|
|
spin_release(&lock->dep_map, 1, _THIS_IP_);
|
|
_raw_spin_unlock(lock);
|
|
preempt_enable_no_resched();
|
|
__cond_resched();
|
|
ret = 1;
|
|
spin_lock(lock);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(cond_resched_lock);
|
|
|
|
int __sched cond_resched_softirq(void)
|
|
{
|
|
BUG_ON(!in_softirq());
|
|
|
|
if (need_resched() && system_state == SYSTEM_RUNNING) {
|
|
raw_local_irq_disable();
|
|
_local_bh_enable();
|
|
raw_local_irq_enable();
|
|
__cond_resched();
|
|
local_bh_disable();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(cond_resched_softirq);
|
|
|
|
/**
|
|
* yield - yield the current processor to other threads.
|
|
*
|
|
* This is a shortcut for kernel-space yielding - it marks the
|
|
* thread runnable and calls sys_sched_yield().
|
|
*/
|
|
void __sched yield(void)
|
|
{
|
|
set_current_state(TASK_RUNNING);
|
|
sys_sched_yield();
|
|
}
|
|
EXPORT_SYMBOL(yield);
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* But don't do that if it is a deliberate, throttling IO wait (this task
|
|
* has set its backing_dev_info: the queue against which it should throttle)
|
|
*/
|
|
void __sched io_schedule(void)
|
|
{
|
|
struct rq *rq = &__raw_get_cpu_var(runqueues);
|
|
|
|
delayacct_blkio_start();
|
|
atomic_inc(&rq->nr_iowait);
|
|
schedule();
|
|
atomic_dec(&rq->nr_iowait);
|
|
delayacct_blkio_end();
|
|
}
|
|
EXPORT_SYMBOL(io_schedule);
|
|
|
|
long __sched io_schedule_timeout(long timeout)
|
|
{
|
|
struct rq *rq = &__raw_get_cpu_var(runqueues);
|
|
long ret;
|
|
|
|
delayacct_blkio_start();
|
|
atomic_inc(&rq->nr_iowait);
|
|
ret = schedule_timeout(timeout);
|
|
atomic_dec(&rq->nr_iowait);
|
|
delayacct_blkio_end();
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_get_priority_max - return maximum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* this syscall returns the maximum rt_priority that can be used
|
|
* by a given scheduling class.
|
|
*/
|
|
asmlinkage long sys_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_NORMAL:
|
|
case SCHED_BATCH:
|
|
ret = 0;
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* sys_sched_get_priority_min - return minimum RT priority.
|
|
* @policy: scheduling class.
|
|
*
|
|
* this syscall returns the minimum rt_priority that can be used
|
|
* by a given scheduling class.
|
|
*/
|
|
asmlinkage long sys_sched_get_priority_min(int policy)
|
|
{
|
|
int ret = -EINVAL;
|
|
|
|
switch (policy) {
|
|
case SCHED_FIFO:
|
|
case SCHED_RR:
|
|
ret = 1;
|
|
break;
|
|
case SCHED_NORMAL:
|
|
case SCHED_BATCH:
|
|
ret = 0;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
asmlinkage
|
|
long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
|
|
{
|
|
struct task_struct *p;
|
|
int retval = -EINVAL;
|
|
struct timespec t;
|
|
|
|
if (pid < 0)
|
|
goto out_nounlock;
|
|
|
|
retval = -ESRCH;
|
|
read_lock(&tasklist_lock);
|
|
p = find_process_by_pid(pid);
|
|
if (!p)
|
|
goto out_unlock;
|
|
|
|
retval = security_task_getscheduler(p);
|
|
if (retval)
|
|
goto out_unlock;
|
|
|
|
jiffies_to_timespec(p->policy == SCHED_FIFO ?
|
|
0 : task_timeslice(p), &t);
|
|
read_unlock(&tasklist_lock);
|
|
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
|
|
out_nounlock:
|
|
return retval;
|
|
out_unlock:
|
|
read_unlock(&tasklist_lock);
|
|
return retval;
|
|
}
|
|
|
|
static inline struct task_struct *eldest_child(struct task_struct *p)
|
|
{
|
|
if (list_empty(&p->children))
|
|
return NULL;
|
|
return list_entry(p->children.next,struct task_struct,sibling);
|
|
}
|
|
|
|
static inline struct task_struct *older_sibling(struct task_struct *p)
|
|
{
|
|
if (p->sibling.prev==&p->parent->children)
|
|
return NULL;
|
|
return list_entry(p->sibling.prev,struct task_struct,sibling);
|
|
}
|
|
|
|
static inline struct task_struct *younger_sibling(struct task_struct *p)
|
|
{
|
|
if (p->sibling.next==&p->parent->children)
|
|
return NULL;
|
|
return list_entry(p->sibling.next,struct task_struct,sibling);
|
|
}
|
|
|
|
static const char stat_nam[] = "RSDTtZX";
|
|
|
|
static void show_task(struct task_struct *p)
|
|
{
|
|
struct task_struct *relative;
|
|
unsigned long free = 0;
|
|
unsigned state;
|
|
|
|
state = p->state ? __ffs(p->state) + 1 : 0;
|
|
printk("%-13.13s %c", p->comm,
|
|
state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
|
|
#if (BITS_PER_LONG == 32)
|
|
if (state == TASK_RUNNING)
|
|
printk(" running ");
|
|
else
|
|
printk(" %08lX ", thread_saved_pc(p));
|
|
#else
|
|
if (state == TASK_RUNNING)
|
|
printk(" running task ");
|
|
else
|
|
printk(" %016lx ", thread_saved_pc(p));
|
|
#endif
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
{
|
|
unsigned long *n = end_of_stack(p);
|
|
while (!*n)
|
|
n++;
|
|
free = (unsigned long)n - (unsigned long)end_of_stack(p);
|
|
}
|
|
#endif
|
|
printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
|
|
if ((relative = eldest_child(p)))
|
|
printk("%5d ", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if ((relative = younger_sibling(p)))
|
|
printk("%7d", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if ((relative = older_sibling(p)))
|
|
printk(" %5d", relative->pid);
|
|
else
|
|
printk(" ");
|
|
if (!p->mm)
|
|
printk(" (L-TLB)\n");
|
|
else
|
|
printk(" (NOTLB)\n");
|
|
|
|
if (state != TASK_RUNNING)
|
|
show_stack(p, NULL);
|
|
}
|
|
|
|
void show_state_filter(unsigned long state_filter)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
#if (BITS_PER_LONG == 32)
|
|
printk("\n"
|
|
" free sibling\n");
|
|
printk(" task PC stack pid father child younger older\n");
|
|
#else
|
|
printk("\n"
|
|
" free sibling\n");
|
|
printk(" task PC stack pid father child younger older\n");
|
|
#endif
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
/*
|
|
* reset the NMI-timeout, listing all files on a slow
|
|
* console might take alot of time:
|
|
*/
|
|
touch_nmi_watchdog();
|
|
if (p->state & state_filter)
|
|
show_task(p);
|
|
} while_each_thread(g, p);
|
|
|
|
read_unlock(&tasklist_lock);
|
|
/*
|
|
* Only show locks if all tasks are dumped:
|
|
*/
|
|
if (state_filter == -1)
|
|
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 __cpuinit init_idle(struct task_struct *idle, int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long flags;
|
|
|
|
idle->timestamp = sched_clock();
|
|
idle->sleep_avg = 0;
|
|
idle->array = NULL;
|
|
idle->prio = idle->normal_prio = MAX_PRIO;
|
|
idle->state = TASK_RUNNING;
|
|
idle->cpus_allowed = cpumask_of_cpu(cpu);
|
|
set_task_cpu(idle, cpu);
|
|
|
|
spin_lock_irqsave(&rq->lock, flags);
|
|
rq->curr = rq->idle = idle;
|
|
#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
|
|
idle->oncpu = 1;
|
|
#endif
|
|
spin_unlock_irqrestore(&rq->lock, flags);
|
|
|
|
/* Set the preempt count _outside_ the spinlocks! */
|
|
#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
|
|
task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
|
|
#else
|
|
task_thread_info(idle)->preempt_count = 0;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* In a system that switches off the HZ timer nohz_cpu_mask
|
|
* indicates which cpus entered this state. This is used
|
|
* in the rcu update to wait only for active cpus. For system
|
|
* which do not switch off the HZ timer nohz_cpu_mask should
|
|
* always be CPU_MASK_NONE.
|
|
*/
|
|
cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* This is how migration works:
|
|
*
|
|
* 1) we queue a struct migration_req structure in the source CPU's
|
|
* runqueue and wake up that CPU's migration thread.
|
|
* 2) we down() the locked semaphore => thread blocks.
|
|
* 3) migration thread wakes up (implicitly it forces the migrated
|
|
* thread off the CPU)
|
|
* 4) it gets the migration request and checks whether the migrated
|
|
* task is still in the wrong runqueue.
|
|
* 5) if it's in the wrong runqueue then the migration thread removes
|
|
* it and puts it into the right queue.
|
|
* 6) migration thread up()s the semaphore.
|
|
* 7) we wake up and the migration is done.
|
|
*/
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
|
|
{
|
|
struct migration_req req;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
int ret = 0;
|
|
|
|
rq = task_rq_lock(p, &flags);
|
|
if (!cpus_intersects(new_mask, cpu_online_map)) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
p->cpus_allowed = new_mask;
|
|
/* Can the task run on the task's current CPU? If so, we're done */
|
|
if (cpu_isset(task_cpu(p), new_mask))
|
|
goto out;
|
|
|
|
if (migrate_task(p, any_online_cpu(new_mask), &req)) {
|
|
/* Need help from migration thread: drop lock and wait. */
|
|
task_rq_unlock(rq, &flags);
|
|
wake_up_process(rq->migration_thread);
|
|
wait_for_completion(&req.done);
|
|
tlb_migrate_finish(p->mm);
|
|
return 0;
|
|
}
|
|
out:
|
|
task_rq_unlock(rq, &flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(set_cpus_allowed);
|
|
|
|
/*
|
|
* Move (not current) task off this cpu, onto dest 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.
|
|
*
|
|
* Returns non-zero if task was successfully migrated.
|
|
*/
|
|
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
|
|
{
|
|
struct rq *rq_dest, *rq_src;
|
|
int ret = 0;
|
|
|
|
if (unlikely(cpu_is_offline(dest_cpu)))
|
|
return ret;
|
|
|
|
rq_src = cpu_rq(src_cpu);
|
|
rq_dest = cpu_rq(dest_cpu);
|
|
|
|
double_rq_lock(rq_src, rq_dest);
|
|
/* Already moved. */
|
|
if (task_cpu(p) != src_cpu)
|
|
goto out;
|
|
/* Affinity changed (again). */
|
|
if (!cpu_isset(dest_cpu, p->cpus_allowed))
|
|
goto out;
|
|
|
|
set_task_cpu(p, dest_cpu);
|
|
if (p->array) {
|
|
/*
|
|
* Sync timestamp with rq_dest's before activating.
|
|
* The same thing could be achieved by doing this step
|
|
* afterwards, and pretending it was a local activate.
|
|
* This way is cleaner and logically correct.
|
|
*/
|
|
p->timestamp = p->timestamp - rq_src->most_recent_timestamp
|
|
+ rq_dest->most_recent_timestamp;
|
|
deactivate_task(p, rq_src);
|
|
__activate_task(p, rq_dest);
|
|
if (TASK_PREEMPTS_CURR(p, rq_dest))
|
|
resched_task(rq_dest->curr);
|
|
}
|
|
ret = 1;
|
|
out:
|
|
double_rq_unlock(rq_src, rq_dest);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* migration_thread - this is a highprio system thread that performs
|
|
* thread migration by bumping thread off CPU then 'pushing' onto
|
|
* another runqueue.
|
|
*/
|
|
static int migration_thread(void *data)
|
|
{
|
|
int cpu = (long)data;
|
|
struct rq *rq;
|
|
|
|
rq = cpu_rq(cpu);
|
|
BUG_ON(rq->migration_thread != current);
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
while (!kthread_should_stop()) {
|
|
struct migration_req *req;
|
|
struct list_head *head;
|
|
|
|
try_to_freeze();
|
|
|
|
spin_lock_irq(&rq->lock);
|
|
|
|
if (cpu_is_offline(cpu)) {
|
|
spin_unlock_irq(&rq->lock);
|
|
goto wait_to_die;
|
|
}
|
|
|
|
if (rq->active_balance) {
|
|
active_load_balance(rq, cpu);
|
|
rq->active_balance = 0;
|
|
}
|
|
|
|
head = &rq->migration_queue;
|
|
|
|
if (list_empty(head)) {
|
|
spin_unlock_irq(&rq->lock);
|
|
schedule();
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
continue;
|
|
}
|
|
req = list_entry(head->next, struct migration_req, list);
|
|
list_del_init(head->next);
|
|
|
|
spin_unlock(&rq->lock);
|
|
__migrate_task(req->task, cpu, req->dest_cpu);
|
|
local_irq_enable();
|
|
|
|
complete(&req->done);
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
return 0;
|
|
|
|
wait_to_die:
|
|
/* Wait for kthread_stop */
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
while (!kthread_should_stop()) {
|
|
schedule();
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
}
|
|
__set_current_state(TASK_RUNNING);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/*
|
|
* Figure out where task on dead CPU should go, use force if neccessary.
|
|
* NOTE: interrupts should be disabled by the caller
|
|
*/
|
|
static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
|
|
{
|
|
unsigned long flags;
|
|
cpumask_t mask;
|
|
struct rq *rq;
|
|
int dest_cpu;
|
|
|
|
restart:
|
|
/* On same node? */
|
|
mask = node_to_cpumask(cpu_to_node(dead_cpu));
|
|
cpus_and(mask, mask, p->cpus_allowed);
|
|
dest_cpu = any_online_cpu(mask);
|
|
|
|
/* On any allowed CPU? */
|
|
if (dest_cpu == NR_CPUS)
|
|
dest_cpu = any_online_cpu(p->cpus_allowed);
|
|
|
|
/* No more Mr. Nice Guy. */
|
|
if (dest_cpu == NR_CPUS) {
|
|
rq = task_rq_lock(p, &flags);
|
|
cpus_setall(p->cpus_allowed);
|
|
dest_cpu = any_online_cpu(p->cpus_allowed);
|
|
task_rq_unlock(rq, &flags);
|
|
|
|
/*
|
|
* 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(KERN_INFO "process %d (%s) no "
|
|
"longer affine to cpu%d\n",
|
|
p->pid, p->comm, dead_cpu);
|
|
}
|
|
if (!__migrate_task(p, dead_cpu, dest_cpu))
|
|
goto restart;
|
|
}
|
|
|
|
/*
|
|
* While a dead CPU has no uninterruptible tasks queued at this point,
|
|
* it might still have a nonzero ->nr_uninterruptible counter, because
|
|
* for performance reasons the counter is not stricly tracking tasks to
|
|
* their home CPUs. So we just add the counter to another CPU's counter,
|
|
* to keep the global sum constant after CPU-down:
|
|
*/
|
|
static void migrate_nr_uninterruptible(struct rq *rq_src)
|
|
{
|
|
struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
double_rq_lock(rq_src, rq_dest);
|
|
rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
|
|
rq_src->nr_uninterruptible = 0;
|
|
double_rq_unlock(rq_src, rq_dest);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/* Run through task list and migrate tasks from the dead cpu. */
|
|
static void migrate_live_tasks(int src_cpu)
|
|
{
|
|
struct task_struct *p, *t;
|
|
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
do_each_thread(t, p) {
|
|
if (p == current)
|
|
continue;
|
|
|
|
if (task_cpu(p) == src_cpu)
|
|
move_task_off_dead_cpu(src_cpu, p);
|
|
} while_each_thread(t, p);
|
|
|
|
write_unlock_irq(&tasklist_lock);
|
|
}
|
|
|
|
/* Schedules idle task to be the next runnable task on current CPU.
|
|
* It does so by boosting its priority to highest possible and adding it to
|
|
* the _front_ of the runqueue. Used by CPU offline code.
|
|
*/
|
|
void sched_idle_next(void)
|
|
{
|
|
int this_cpu = smp_processor_id();
|
|
struct rq *rq = cpu_rq(this_cpu);
|
|
struct task_struct *p = rq->idle;
|
|
unsigned long flags;
|
|
|
|
/* cpu has to be offline */
|
|
BUG_ON(cpu_online(this_cpu));
|
|
|
|
/*
|
|
* Strictly not necessary since rest of the CPUs are stopped by now
|
|
* and interrupts disabled on the current cpu.
|
|
*/
|
|
spin_lock_irqsave(&rq->lock, flags);
|
|
|
|
__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
|
|
|
|
/* Add idle task to the _front_ of its priority queue: */
|
|
__activate_idle_task(p, rq);
|
|
|
|
spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Ensures 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()));
|
|
|
|
if (mm != &init_mm)
|
|
switch_mm(mm, &init_mm, current);
|
|
mmdrop(mm);
|
|
}
|
|
|
|
/* called under rq->lock with disabled interrupts */
|
|
static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
|
|
{
|
|
struct rq *rq = cpu_rq(dead_cpu);
|
|
|
|
/* Must be exiting, otherwise would be on tasklist. */
|
|
BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
|
|
|
|
/* Cannot have done final schedule yet: would have vanished. */
|
|
BUG_ON(p->state == TASK_DEAD);
|
|
|
|
get_task_struct(p);
|
|
|
|
/*
|
|
* Drop lock around migration; if someone else moves it,
|
|
* that's OK. No task can be added to this CPU, so iteration is
|
|
* fine.
|
|
* NOTE: interrupts should be left disabled --dev@
|
|
*/
|
|
spin_unlock(&rq->lock);
|
|
move_task_off_dead_cpu(dead_cpu, p);
|
|
spin_lock(&rq->lock);
|
|
|
|
put_task_struct(p);
|
|
}
|
|
|
|
/* release_task() removes task from tasklist, so we won't find dead tasks. */
|
|
static void migrate_dead_tasks(unsigned int dead_cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(dead_cpu);
|
|
unsigned int arr, i;
|
|
|
|
for (arr = 0; arr < 2; arr++) {
|
|
for (i = 0; i < MAX_PRIO; i++) {
|
|
struct list_head *list = &rq->arrays[arr].queue[i];
|
|
|
|
while (!list_empty(list))
|
|
migrate_dead(dead_cpu, list_entry(list->next,
|
|
struct task_struct, run_list));
|
|
}
|
|
}
|
|
}
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
/*
|
|
* migration_call - callback that gets triggered when a CPU is added.
|
|
* Here we can start up the necessary migration thread for the new CPU.
|
|
*/
|
|
static int __cpuinit
|
|
migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
|
{
|
|
struct task_struct *p;
|
|
int cpu = (long)hcpu;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
|
|
if (IS_ERR(p))
|
|
return NOTIFY_BAD;
|
|
p->flags |= PF_NOFREEZE;
|
|
kthread_bind(p, cpu);
|
|
/* Must be high prio: stop_machine expects to yield to it. */
|
|
rq = task_rq_lock(p, &flags);
|
|
__setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
|
|
task_rq_unlock(rq, &flags);
|
|
cpu_rq(cpu)->migration_thread = p;
|
|
break;
|
|
|
|
case CPU_ONLINE:
|
|
/* Strictly unneccessary, as first user will wake it. */
|
|
wake_up_process(cpu_rq(cpu)->migration_thread);
|
|
break;
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
case CPU_UP_CANCELED:
|
|
if (!cpu_rq(cpu)->migration_thread)
|
|
break;
|
|
/* Unbind it from offline cpu so it can run. Fall thru. */
|
|
kthread_bind(cpu_rq(cpu)->migration_thread,
|
|
any_online_cpu(cpu_online_map));
|
|
kthread_stop(cpu_rq(cpu)->migration_thread);
|
|
cpu_rq(cpu)->migration_thread = NULL;
|
|
break;
|
|
|
|
case CPU_DEAD:
|
|
migrate_live_tasks(cpu);
|
|
rq = cpu_rq(cpu);
|
|
kthread_stop(rq->migration_thread);
|
|
rq->migration_thread = NULL;
|
|
/* Idle task back to normal (off runqueue, low prio) */
|
|
rq = task_rq_lock(rq->idle, &flags);
|
|
deactivate_task(rq->idle, rq);
|
|
rq->idle->static_prio = MAX_PRIO;
|
|
__setscheduler(rq->idle, SCHED_NORMAL, 0);
|
|
migrate_dead_tasks(cpu);
|
|
task_rq_unlock(rq, &flags);
|
|
migrate_nr_uninterruptible(rq);
|
|
BUG_ON(rq->nr_running != 0);
|
|
|
|
/* No need to migrate the tasks: it was best-effort if
|
|
* they didn't do lock_cpu_hotplug(). Just wake up
|
|
* the requestors. */
|
|
spin_lock_irq(&rq->lock);
|
|
while (!list_empty(&rq->migration_queue)) {
|
|
struct migration_req *req;
|
|
|
|
req = list_entry(rq->migration_queue.next,
|
|
struct migration_req, list);
|
|
list_del_init(&req->list);
|
|
complete(&req->done);
|
|
}
|
|
spin_unlock_irq(&rq->lock);
|
|
break;
|
|
#endif
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
/* Register at highest priority so that task migration (migrate_all_tasks)
|
|
* happens before everything else.
|
|
*/
|
|
static struct notifier_block __cpuinitdata migration_notifier = {
|
|
.notifier_call = migration_call,
|
|
.priority = 10
|
|
};
|
|
|
|
int __init migration_init(void)
|
|
{
|
|
void *cpu = (void *)(long)smp_processor_id();
|
|
int err;
|
|
|
|
/* Start one for the boot CPU: */
|
|
err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
|
|
BUG_ON(err == NOTIFY_BAD);
|
|
migration_call(&migration_notifier, CPU_ONLINE, cpu);
|
|
register_cpu_notifier(&migration_notifier);
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
#undef SCHED_DOMAIN_DEBUG
|
|
#ifdef SCHED_DOMAIN_DEBUG
|
|
static void sched_domain_debug(struct sched_domain *sd, int cpu)
|
|
{
|
|
int level = 0;
|
|
|
|
if (!sd) {
|
|
printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
|
|
return;
|
|
}
|
|
|
|
printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
|
|
|
|
do {
|
|
int i;
|
|
char str[NR_CPUS];
|
|
struct sched_group *group = sd->groups;
|
|
cpumask_t groupmask;
|
|
|
|
cpumask_scnprintf(str, NR_CPUS, sd->span);
|
|
cpus_clear(groupmask);
|
|
|
|
printk(KERN_DEBUG);
|
|
for (i = 0; i < level + 1; i++)
|
|
printk(" ");
|
|
printk("domain %d: ", level);
|
|
|
|
if (!(sd->flags & SD_LOAD_BALANCE)) {
|
|
printk("does not load-balance\n");
|
|
if (sd->parent)
|
|
printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
|
|
" has parent");
|
|
break;
|
|
}
|
|
|
|
printk("span %s\n", str);
|
|
|
|
if (!cpu_isset(cpu, sd->span))
|
|
printk(KERN_ERR "ERROR: domain->span does not contain "
|
|
"CPU%d\n", cpu);
|
|
if (!cpu_isset(cpu, group->cpumask))
|
|
printk(KERN_ERR "ERROR: domain->groups does not contain"
|
|
" CPU%d\n", cpu);
|
|
|
|
printk(KERN_DEBUG);
|
|
for (i = 0; i < level + 2; i++)
|
|
printk(" ");
|
|
printk("groups:");
|
|
do {
|
|
if (!group) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: group is NULL\n");
|
|
break;
|
|
}
|
|
|
|
if (!group->cpu_power) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: domain->cpu_power not "
|
|
"set\n");
|
|
}
|
|
|
|
if (!cpus_weight(group->cpumask)) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: empty group\n");
|
|
}
|
|
|
|
if (cpus_intersects(groupmask, group->cpumask)) {
|
|
printk("\n");
|
|
printk(KERN_ERR "ERROR: repeated CPUs\n");
|
|
}
|
|
|
|
cpus_or(groupmask, groupmask, group->cpumask);
|
|
|
|
cpumask_scnprintf(str, NR_CPUS, group->cpumask);
|
|
printk(" %s", str);
|
|
|
|
group = group->next;
|
|
} while (group != sd->groups);
|
|
printk("\n");
|
|
|
|
if (!cpus_equal(sd->span, groupmask))
|
|
printk(KERN_ERR "ERROR: groups don't span "
|
|
"domain->span\n");
|
|
|
|
level++;
|
|
sd = sd->parent;
|
|
if (!sd)
|
|
continue;
|
|
|
|
if (!cpus_subset(groupmask, sd->span))
|
|
printk(KERN_ERR "ERROR: parent span is not a superset "
|
|
"of domain->span\n");
|
|
|
|
} while (sd);
|
|
}
|
|
#else
|
|
# define sched_domain_debug(sd, cpu) do { } while (0)
|
|
#endif
|
|
|
|
static int sd_degenerate(struct sched_domain *sd)
|
|
{
|
|
if (cpus_weight(sd->span) == 1)
|
|
return 1;
|
|
|
|
/* Following flags need at least 2 groups */
|
|
if (sd->flags & (SD_LOAD_BALANCE |
|
|
SD_BALANCE_NEWIDLE |
|
|
SD_BALANCE_FORK |
|
|
SD_BALANCE_EXEC |
|
|
SD_SHARE_CPUPOWER |
|
|
SD_SHARE_PKG_RESOURCES)) {
|
|
if (sd->groups != sd->groups->next)
|
|
return 0;
|
|
}
|
|
|
|
/* Following flags don't use groups */
|
|
if (sd->flags & (SD_WAKE_IDLE |
|
|
SD_WAKE_AFFINE |
|
|
SD_WAKE_BALANCE))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
|
|
{
|
|
unsigned long cflags = sd->flags, pflags = parent->flags;
|
|
|
|
if (sd_degenerate(parent))
|
|
return 1;
|
|
|
|
if (!cpus_equal(sd->span, parent->span))
|
|
return 0;
|
|
|
|
/* Does parent contain flags not in child? */
|
|
/* WAKE_BALANCE is a subset of WAKE_AFFINE */
|
|
if (cflags & SD_WAKE_AFFINE)
|
|
pflags &= ~SD_WAKE_BALANCE;
|
|
/* Flags needing groups don't count if only 1 group in parent */
|
|
if (parent->groups == parent->groups->next) {
|
|
pflags &= ~(SD_LOAD_BALANCE |
|
|
SD_BALANCE_NEWIDLE |
|
|
SD_BALANCE_FORK |
|
|
SD_BALANCE_EXEC |
|
|
SD_SHARE_CPUPOWER |
|
|
SD_SHARE_PKG_RESOURCES);
|
|
}
|
|
if (~cflags & pflags)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Attach the domain 'sd' to 'cpu' as its base domain. Callers must
|
|
* hold the hotplug lock.
|
|
*/
|
|
static void cpu_attach_domain(struct sched_domain *sd, int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct sched_domain *tmp;
|
|
|
|
/* Remove the sched domains which do not contribute to scheduling. */
|
|
for (tmp = sd; tmp; tmp = tmp->parent) {
|
|
struct sched_domain *parent = tmp->parent;
|
|
if (!parent)
|
|
break;
|
|
if (sd_parent_degenerate(tmp, parent)) {
|
|
tmp->parent = parent->parent;
|
|
if (parent->parent)
|
|
parent->parent->child = tmp;
|
|
}
|
|
}
|
|
|
|
if (sd && sd_degenerate(sd)) {
|
|
sd = sd->parent;
|
|
if (sd)
|
|
sd->child = NULL;
|
|
}
|
|
|
|
sched_domain_debug(sd, cpu);
|
|
|
|
rcu_assign_pointer(rq->sd, sd);
|
|
}
|
|
|
|
/* cpus with isolated domains */
|
|
static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
|
|
|
|
/* Setup the mask of cpus configured for isolated domains */
|
|
static int __init isolated_cpu_setup(char *str)
|
|
{
|
|
int ints[NR_CPUS], i;
|
|
|
|
str = get_options(str, ARRAY_SIZE(ints), ints);
|
|
cpus_clear(cpu_isolated_map);
|
|
for (i = 1; i <= ints[0]; i++)
|
|
if (ints[i] < NR_CPUS)
|
|
cpu_set(ints[i], cpu_isolated_map);
|
|
return 1;
|
|
}
|
|
|
|
__setup ("isolcpus=", isolated_cpu_setup);
|
|
|
|
/*
|
|
* init_sched_build_groups takes the cpumask we wish to span, and a pointer
|
|
* to a function which identifies what group(along with sched group) a CPU
|
|
* belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
|
|
* (due to the fact that we keep track of groups covered with a cpumask_t).
|
|
*
|
|
* init_sched_build_groups will build a circular linked list of the groups
|
|
* covered by the given span, and will set each group's ->cpumask correctly,
|
|
* and ->cpu_power to 0.
|
|
*/
|
|
static void
|
|
init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map,
|
|
int (*group_fn)(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg))
|
|
{
|
|
struct sched_group *first = NULL, *last = NULL;
|
|
cpumask_t covered = CPU_MASK_NONE;
|
|
int i;
|
|
|
|
for_each_cpu_mask(i, span) {
|
|
struct sched_group *sg;
|
|
int group = group_fn(i, cpu_map, &sg);
|
|
int j;
|
|
|
|
if (cpu_isset(i, covered))
|
|
continue;
|
|
|
|
sg->cpumask = CPU_MASK_NONE;
|
|
sg->cpu_power = 0;
|
|
|
|
for_each_cpu_mask(j, span) {
|
|
if (group_fn(j, cpu_map, NULL) != group)
|
|
continue;
|
|
|
|
cpu_set(j, covered);
|
|
cpu_set(j, sg->cpumask);
|
|
}
|
|
if (!first)
|
|
first = sg;
|
|
if (last)
|
|
last->next = sg;
|
|
last = sg;
|
|
}
|
|
last->next = first;
|
|
}
|
|
|
|
#define SD_NODES_PER_DOMAIN 16
|
|
|
|
/*
|
|
* Self-tuning task migration cost measurement between source and target CPUs.
|
|
*
|
|
* This is done by measuring the cost of manipulating buffers of varying
|
|
* sizes. For a given buffer-size here are the steps that are taken:
|
|
*
|
|
* 1) the source CPU reads+dirties a shared buffer
|
|
* 2) the target CPU reads+dirties the same shared buffer
|
|
*
|
|
* We measure how long they take, in the following 4 scenarios:
|
|
*
|
|
* - source: CPU1, target: CPU2 | cost1
|
|
* - source: CPU2, target: CPU1 | cost2
|
|
* - source: CPU1, target: CPU1 | cost3
|
|
* - source: CPU2, target: CPU2 | cost4
|
|
*
|
|
* We then calculate the cost3+cost4-cost1-cost2 difference - this is
|
|
* the cost of migration.
|
|
*
|
|
* We then start off from a small buffer-size and iterate up to larger
|
|
* buffer sizes, in 5% steps - measuring each buffer-size separately, and
|
|
* doing a maximum search for the cost. (The maximum cost for a migration
|
|
* normally occurs when the working set size is around the effective cache
|
|
* size.)
|
|
*/
|
|
#define SEARCH_SCOPE 2
|
|
#define MIN_CACHE_SIZE (64*1024U)
|
|
#define DEFAULT_CACHE_SIZE (5*1024*1024U)
|
|
#define ITERATIONS 1
|
|
#define SIZE_THRESH 130
|
|
#define COST_THRESH 130
|
|
|
|
/*
|
|
* The migration cost is a function of 'domain distance'. Domain
|
|
* distance is the number of steps a CPU has to iterate down its
|
|
* domain tree to share a domain with the other CPU. The farther
|
|
* two CPUs are from each other, the larger the distance gets.
|
|
*
|
|
* Note that we use the distance only to cache measurement results,
|
|
* the distance value is not used numerically otherwise. When two
|
|
* CPUs have the same distance it is assumed that the migration
|
|
* cost is the same. (this is a simplification but quite practical)
|
|
*/
|
|
#define MAX_DOMAIN_DISTANCE 32
|
|
|
|
static unsigned long long migration_cost[MAX_DOMAIN_DISTANCE] =
|
|
{ [ 0 ... MAX_DOMAIN_DISTANCE-1 ] =
|
|
/*
|
|
* Architectures may override the migration cost and thus avoid
|
|
* boot-time calibration. Unit is nanoseconds. Mostly useful for
|
|
* virtualized hardware:
|
|
*/
|
|
#ifdef CONFIG_DEFAULT_MIGRATION_COST
|
|
CONFIG_DEFAULT_MIGRATION_COST
|
|
#else
|
|
-1LL
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* Allow override of migration cost - in units of microseconds.
|
|
* E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
|
|
* of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
|
|
*/
|
|
static int __init migration_cost_setup(char *str)
|
|
{
|
|
int ints[MAX_DOMAIN_DISTANCE+1], i;
|
|
|
|
str = get_options(str, ARRAY_SIZE(ints), ints);
|
|
|
|
printk("#ints: %d\n", ints[0]);
|
|
for (i = 1; i <= ints[0]; i++) {
|
|
migration_cost[i-1] = (unsigned long long)ints[i]*1000;
|
|
printk("migration_cost[%d]: %Ld\n", i-1, migration_cost[i-1]);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
__setup ("migration_cost=", migration_cost_setup);
|
|
|
|
/*
|
|
* Global multiplier (divisor) for migration-cutoff values,
|
|
* in percentiles. E.g. use a value of 150 to get 1.5 times
|
|
* longer cache-hot cutoff times.
|
|
*
|
|
* (We scale it from 100 to 128 to long long handling easier.)
|
|
*/
|
|
|
|
#define MIGRATION_FACTOR_SCALE 128
|
|
|
|
static unsigned int migration_factor = MIGRATION_FACTOR_SCALE;
|
|
|
|
static int __init setup_migration_factor(char *str)
|
|
{
|
|
get_option(&str, &migration_factor);
|
|
migration_factor = migration_factor * MIGRATION_FACTOR_SCALE / 100;
|
|
return 1;
|
|
}
|
|
|
|
__setup("migration_factor=", setup_migration_factor);
|
|
|
|
/*
|
|
* Estimated distance of two CPUs, measured via the number of domains
|
|
* we have to pass for the two CPUs to be in the same span:
|
|
*/
|
|
static unsigned long domain_distance(int cpu1, int cpu2)
|
|
{
|
|
unsigned long distance = 0;
|
|
struct sched_domain *sd;
|
|
|
|
for_each_domain(cpu1, sd) {
|
|
WARN_ON(!cpu_isset(cpu1, sd->span));
|
|
if (cpu_isset(cpu2, sd->span))
|
|
return distance;
|
|
distance++;
|
|
}
|
|
if (distance >= MAX_DOMAIN_DISTANCE) {
|
|
WARN_ON(1);
|
|
distance = MAX_DOMAIN_DISTANCE-1;
|
|
}
|
|
|
|
return distance;
|
|
}
|
|
|
|
static unsigned int migration_debug;
|
|
|
|
static int __init setup_migration_debug(char *str)
|
|
{
|
|
get_option(&str, &migration_debug);
|
|
return 1;
|
|
}
|
|
|
|
__setup("migration_debug=", setup_migration_debug);
|
|
|
|
/*
|
|
* Maximum cache-size that the scheduler should try to measure.
|
|
* Architectures with larger caches should tune this up during
|
|
* bootup. Gets used in the domain-setup code (i.e. during SMP
|
|
* bootup).
|
|
*/
|
|
unsigned int max_cache_size;
|
|
|
|
static int __init setup_max_cache_size(char *str)
|
|
{
|
|
get_option(&str, &max_cache_size);
|
|
return 1;
|
|
}
|
|
|
|
__setup("max_cache_size=", setup_max_cache_size);
|
|
|
|
/*
|
|
* Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
|
|
* is the operation that is timed, so we try to generate unpredictable
|
|
* cachemisses that still end up filling the L2 cache:
|
|
*/
|
|
static void touch_cache(void *__cache, unsigned long __size)
|
|
{
|
|
unsigned long size = __size / sizeof(long);
|
|
unsigned long chunk1 = size / 3;
|
|
unsigned long chunk2 = 2 * size / 3;
|
|
unsigned long *cache = __cache;
|
|
int i;
|
|
|
|
for (i = 0; i < size/6; i += 8) {
|
|
switch (i % 6) {
|
|
case 0: cache[i]++;
|
|
case 1: cache[size-1-i]++;
|
|
case 2: cache[chunk1-i]++;
|
|
case 3: cache[chunk1+i]++;
|
|
case 4: cache[chunk2-i]++;
|
|
case 5: cache[chunk2+i]++;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Measure the cache-cost of one task migration. Returns in units of nsec.
|
|
*/
|
|
static unsigned long long
|
|
measure_one(void *cache, unsigned long size, int source, int target)
|
|
{
|
|
cpumask_t mask, saved_mask;
|
|
unsigned long long t0, t1, t2, t3, cost;
|
|
|
|
saved_mask = current->cpus_allowed;
|
|
|
|
/*
|
|
* Flush source caches to RAM and invalidate them:
|
|
*/
|
|
sched_cacheflush();
|
|
|
|
/*
|
|
* Migrate to the source CPU:
|
|
*/
|
|
mask = cpumask_of_cpu(source);
|
|
set_cpus_allowed(current, mask);
|
|
WARN_ON(smp_processor_id() != source);
|
|
|
|
/*
|
|
* Dirty the working set:
|
|
*/
|
|
t0 = sched_clock();
|
|
touch_cache(cache, size);
|
|
t1 = sched_clock();
|
|
|
|
/*
|
|
* Migrate to the target CPU, dirty the L2 cache and access
|
|
* the shared buffer. (which represents the working set
|
|
* of a migrated task.)
|
|
*/
|
|
mask = cpumask_of_cpu(target);
|
|
set_cpus_allowed(current, mask);
|
|
WARN_ON(smp_processor_id() != target);
|
|
|
|
t2 = sched_clock();
|
|
touch_cache(cache, size);
|
|
t3 = sched_clock();
|
|
|
|
cost = t1-t0 + t3-t2;
|
|
|
|
if (migration_debug >= 2)
|
|
printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
|
|
source, target, t1-t0, t1-t0, t3-t2, cost);
|
|
/*
|
|
* Flush target caches to RAM and invalidate them:
|
|
*/
|
|
sched_cacheflush();
|
|
|
|
set_cpus_allowed(current, saved_mask);
|
|
|
|
return cost;
|
|
}
|
|
|
|
/*
|
|
* Measure a series of task migrations and return the average
|
|
* result. Since this code runs early during bootup the system
|
|
* is 'undisturbed' and the average latency makes sense.
|
|
*
|
|
* The algorithm in essence auto-detects the relevant cache-size,
|
|
* so it will properly detect different cachesizes for different
|
|
* cache-hierarchies, depending on how the CPUs are connected.
|
|
*
|
|
* Architectures can prime the upper limit of the search range via
|
|
* max_cache_size, otherwise the search range defaults to 20MB...64K.
|
|
*/
|
|
static unsigned long long
|
|
measure_cost(int cpu1, int cpu2, void *cache, unsigned int size)
|
|
{
|
|
unsigned long long cost1, cost2;
|
|
int i;
|
|
|
|
/*
|
|
* Measure the migration cost of 'size' bytes, over an
|
|
* average of 10 runs:
|
|
*
|
|
* (We perturb the cache size by a small (0..4k)
|
|
* value to compensate size/alignment related artifacts.
|
|
* We also subtract the cost of the operation done on
|
|
* the same CPU.)
|
|
*/
|
|
cost1 = 0;
|
|
|
|
/*
|
|
* dry run, to make sure we start off cache-cold on cpu1,
|
|
* and to get any vmalloc pagefaults in advance:
|
|
*/
|
|
measure_one(cache, size, cpu1, cpu2);
|
|
for (i = 0; i < ITERATIONS; i++)
|
|
cost1 += measure_one(cache, size - i * 1024, cpu1, cpu2);
|
|
|
|
measure_one(cache, size, cpu2, cpu1);
|
|
for (i = 0; i < ITERATIONS; i++)
|
|
cost1 += measure_one(cache, size - i * 1024, cpu2, cpu1);
|
|
|
|
/*
|
|
* (We measure the non-migrating [cached] cost on both
|
|
* cpu1 and cpu2, to handle CPUs with different speeds)
|
|
*/
|
|
cost2 = 0;
|
|
|
|
measure_one(cache, size, cpu1, cpu1);
|
|
for (i = 0; i < ITERATIONS; i++)
|
|
cost2 += measure_one(cache, size - i * 1024, cpu1, cpu1);
|
|
|
|
measure_one(cache, size, cpu2, cpu2);
|
|
for (i = 0; i < ITERATIONS; i++)
|
|
cost2 += measure_one(cache, size - i * 1024, cpu2, cpu2);
|
|
|
|
/*
|
|
* Get the per-iteration migration cost:
|
|
*/
|
|
do_div(cost1, 2 * ITERATIONS);
|
|
do_div(cost2, 2 * ITERATIONS);
|
|
|
|
return cost1 - cost2;
|
|
}
|
|
|
|
static unsigned long long measure_migration_cost(int cpu1, int cpu2)
|
|
{
|
|
unsigned long long max_cost = 0, fluct = 0, avg_fluct = 0;
|
|
unsigned int max_size, size, size_found = 0;
|
|
long long cost = 0, prev_cost;
|
|
void *cache;
|
|
|
|
/*
|
|
* Search from max_cache_size*5 down to 64K - the real relevant
|
|
* cachesize has to lie somewhere inbetween.
|
|
*/
|
|
if (max_cache_size) {
|
|
max_size = max(max_cache_size * SEARCH_SCOPE, MIN_CACHE_SIZE);
|
|
size = max(max_cache_size / SEARCH_SCOPE, MIN_CACHE_SIZE);
|
|
} else {
|
|
/*
|
|
* Since we have no estimation about the relevant
|
|
* search range
|
|
*/
|
|
max_size = DEFAULT_CACHE_SIZE * SEARCH_SCOPE;
|
|
size = MIN_CACHE_SIZE;
|
|
}
|
|
|
|
if (!cpu_online(cpu1) || !cpu_online(cpu2)) {
|
|
printk("cpu %d and %d not both online!\n", cpu1, cpu2);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Allocate the working set:
|
|
*/
|
|
cache = vmalloc(max_size);
|
|
if (!cache) {
|
|
printk("could not vmalloc %d bytes for cache!\n", 2 * max_size);
|
|
return 1000000; /* return 1 msec on very small boxen */
|
|
}
|
|
|
|
while (size <= max_size) {
|
|
prev_cost = cost;
|
|
cost = measure_cost(cpu1, cpu2, cache, size);
|
|
|
|
/*
|
|
* Update the max:
|
|
*/
|
|
if (cost > 0) {
|
|
if (max_cost < cost) {
|
|
max_cost = cost;
|
|
size_found = size;
|
|
}
|
|
}
|
|
/*
|
|
* Calculate average fluctuation, we use this to prevent
|
|
* noise from triggering an early break out of the loop:
|
|
*/
|
|
fluct = abs(cost - prev_cost);
|
|
avg_fluct = (avg_fluct + fluct)/2;
|
|
|
|
if (migration_debug)
|
|
printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): "
|
|
"(%8Ld %8Ld)\n",
|
|
cpu1, cpu2, size,
|
|
(long)cost / 1000000,
|
|
((long)cost / 100000) % 10,
|
|
(long)max_cost / 1000000,
|
|
((long)max_cost / 100000) % 10,
|
|
domain_distance(cpu1, cpu2),
|
|
cost, avg_fluct);
|
|
|
|
/*
|
|
* If we iterated at least 20% past the previous maximum,
|
|
* and the cost has dropped by more than 20% already,
|
|
* (taking fluctuations into account) then we assume to
|
|
* have found the maximum and break out of the loop early:
|
|
*/
|
|
if (size_found && (size*100 > size_found*SIZE_THRESH))
|
|
if (cost+avg_fluct <= 0 ||
|
|
max_cost*100 > (cost+avg_fluct)*COST_THRESH) {
|
|
|
|
if (migration_debug)
|
|
printk("-> found max.\n");
|
|
break;
|
|
}
|
|
/*
|
|
* Increase the cachesize in 10% steps:
|
|
*/
|
|
size = size * 10 / 9;
|
|
}
|
|
|
|
if (migration_debug)
|
|
printk("[%d][%d] working set size found: %d, cost: %Ld\n",
|
|
cpu1, cpu2, size_found, max_cost);
|
|
|
|
vfree(cache);
|
|
|
|
/*
|
|
* A task is considered 'cache cold' if at least 2 times
|
|
* the worst-case cost of migration has passed.
|
|
*
|
|
* (this limit is only listened to if the load-balancing
|
|
* situation is 'nice' - if there is a large imbalance we
|
|
* ignore it for the sake of CPU utilization and
|
|
* processing fairness.)
|
|
*/
|
|
return 2 * max_cost * migration_factor / MIGRATION_FACTOR_SCALE;
|
|
}
|
|
|
|
static void calibrate_migration_costs(const cpumask_t *cpu_map)
|
|
{
|
|
int cpu1 = -1, cpu2 = -1, cpu, orig_cpu = raw_smp_processor_id();
|
|
unsigned long j0, j1, distance, max_distance = 0;
|
|
struct sched_domain *sd;
|
|
|
|
j0 = jiffies;
|
|
|
|
/*
|
|
* First pass - calculate the cacheflush times:
|
|
*/
|
|
for_each_cpu_mask(cpu1, *cpu_map) {
|
|
for_each_cpu_mask(cpu2, *cpu_map) {
|
|
if (cpu1 == cpu2)
|
|
continue;
|
|
distance = domain_distance(cpu1, cpu2);
|
|
max_distance = max(max_distance, distance);
|
|
/*
|
|
* No result cached yet?
|
|
*/
|
|
if (migration_cost[distance] == -1LL)
|
|
migration_cost[distance] =
|
|
measure_migration_cost(cpu1, cpu2);
|
|
}
|
|
}
|
|
/*
|
|
* Second pass - update the sched domain hierarchy with
|
|
* the new cache-hot-time estimations:
|
|
*/
|
|
for_each_cpu_mask(cpu, *cpu_map) {
|
|
distance = 0;
|
|
for_each_domain(cpu, sd) {
|
|
sd->cache_hot_time = migration_cost[distance];
|
|
distance++;
|
|
}
|
|
}
|
|
/*
|
|
* Print the matrix:
|
|
*/
|
|
if (migration_debug)
|
|
printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
|
|
max_cache_size,
|
|
#ifdef CONFIG_X86
|
|
cpu_khz/1000
|
|
#else
|
|
-1
|
|
#endif
|
|
);
|
|
if (system_state == SYSTEM_BOOTING && num_online_cpus() > 1) {
|
|
printk("migration_cost=");
|
|
for (distance = 0; distance <= max_distance; distance++) {
|
|
if (distance)
|
|
printk(",");
|
|
printk("%ld", (long)migration_cost[distance] / 1000);
|
|
}
|
|
printk("\n");
|
|
}
|
|
j1 = jiffies;
|
|
if (migration_debug)
|
|
printk("migration: %ld seconds\n", (j1-j0) / HZ);
|
|
|
|
/*
|
|
* Move back to the original CPU. NUMA-Q gets confused
|
|
* if we migrate to another quad during bootup.
|
|
*/
|
|
if (raw_smp_processor_id() != orig_cpu) {
|
|
cpumask_t mask = cpumask_of_cpu(orig_cpu),
|
|
saved_mask = current->cpus_allowed;
|
|
|
|
set_cpus_allowed(current, mask);
|
|
set_cpus_allowed(current, saved_mask);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
|
|
/**
|
|
* find_next_best_node - find the next node to include in a sched_domain
|
|
* @node: node whose sched_domain we're building
|
|
* @used_nodes: nodes already in the sched_domain
|
|
*
|
|
* Find the next node to include in a given scheduling domain. Simply
|
|
* finds the closest node not already in the @used_nodes map.
|
|
*
|
|
* Should use nodemask_t.
|
|
*/
|
|
static int find_next_best_node(int node, unsigned long *used_nodes)
|
|
{
|
|
int i, n, val, min_val, best_node = 0;
|
|
|
|
min_val = INT_MAX;
|
|
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
/* Start at @node */
|
|
n = (node + i) % MAX_NUMNODES;
|
|
|
|
if (!nr_cpus_node(n))
|
|
continue;
|
|
|
|
/* Skip already used nodes */
|
|
if (test_bit(n, used_nodes))
|
|
continue;
|
|
|
|
/* Simple min distance search */
|
|
val = node_distance(node, n);
|
|
|
|
if (val < min_val) {
|
|
min_val = val;
|
|
best_node = n;
|
|
}
|
|
}
|
|
|
|
set_bit(best_node, used_nodes);
|
|
return best_node;
|
|
}
|
|
|
|
/**
|
|
* sched_domain_node_span - get a cpumask for a node's sched_domain
|
|
* @node: node whose cpumask we're constructing
|
|
* @size: number of nodes to include in this span
|
|
*
|
|
* Given a node, construct a good cpumask for its sched_domain to span. It
|
|
* should be one that prevents unnecessary balancing, but also spreads tasks
|
|
* out optimally.
|
|
*/
|
|
static cpumask_t sched_domain_node_span(int node)
|
|
{
|
|
DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
|
|
cpumask_t span, nodemask;
|
|
int i;
|
|
|
|
cpus_clear(span);
|
|
bitmap_zero(used_nodes, MAX_NUMNODES);
|
|
|
|
nodemask = node_to_cpumask(node);
|
|
cpus_or(span, span, nodemask);
|
|
set_bit(node, used_nodes);
|
|
|
|
for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
|
|
int next_node = find_next_best_node(node, used_nodes);
|
|
|
|
nodemask = node_to_cpumask(next_node);
|
|
cpus_or(span, span, nodemask);
|
|
}
|
|
|
|
return span;
|
|
}
|
|
#endif
|
|
|
|
int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
|
|
|
|
/*
|
|
* SMT sched-domains:
|
|
*/
|
|
#ifdef CONFIG_SCHED_SMT
|
|
static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
|
|
static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
|
|
|
|
static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg)
|
|
{
|
|
if (sg)
|
|
*sg = &per_cpu(sched_group_cpus, cpu);
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* multi-core sched-domains:
|
|
*/
|
|
#ifdef CONFIG_SCHED_MC
|
|
static DEFINE_PER_CPU(struct sched_domain, core_domains);
|
|
static DEFINE_PER_CPU(struct sched_group, sched_group_core);
|
|
#endif
|
|
|
|
#if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
|
|
static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg)
|
|
{
|
|
int group;
|
|
cpumask_t mask = cpu_sibling_map[cpu];
|
|
cpus_and(mask, mask, *cpu_map);
|
|
group = first_cpu(mask);
|
|
if (sg)
|
|
*sg = &per_cpu(sched_group_core, group);
|
|
return group;
|
|
}
|
|
#elif defined(CONFIG_SCHED_MC)
|
|
static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg)
|
|
{
|
|
if (sg)
|
|
*sg = &per_cpu(sched_group_core, cpu);
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
static DEFINE_PER_CPU(struct sched_domain, phys_domains);
|
|
static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
|
|
|
|
static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg)
|
|
{
|
|
int group;
|
|
#ifdef CONFIG_SCHED_MC
|
|
cpumask_t mask = cpu_coregroup_map(cpu);
|
|
cpus_and(mask, mask, *cpu_map);
|
|
group = first_cpu(mask);
|
|
#elif defined(CONFIG_SCHED_SMT)
|
|
cpumask_t mask = cpu_sibling_map[cpu];
|
|
cpus_and(mask, mask, *cpu_map);
|
|
group = first_cpu(mask);
|
|
#else
|
|
group = cpu;
|
|
#endif
|
|
if (sg)
|
|
*sg = &per_cpu(sched_group_phys, group);
|
|
return group;
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/*
|
|
* The init_sched_build_groups can't handle what we want to do with node
|
|
* groups, so roll our own. Now each node has its own list of groups which
|
|
* gets dynamically allocated.
|
|
*/
|
|
static DEFINE_PER_CPU(struct sched_domain, node_domains);
|
|
static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
|
|
|
|
static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
|
|
static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
|
|
|
|
static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
|
|
struct sched_group **sg)
|
|
{
|
|
cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu));
|
|
int group;
|
|
|
|
cpus_and(nodemask, nodemask, *cpu_map);
|
|
group = first_cpu(nodemask);
|
|
|
|
if (sg)
|
|
*sg = &per_cpu(sched_group_allnodes, group);
|
|
return group;
|
|
}
|
|
|
|
static void init_numa_sched_groups_power(struct sched_group *group_head)
|
|
{
|
|
struct sched_group *sg = group_head;
|
|
int j;
|
|
|
|
if (!sg)
|
|
return;
|
|
next_sg:
|
|
for_each_cpu_mask(j, sg->cpumask) {
|
|
struct sched_domain *sd;
|
|
|
|
sd = &per_cpu(phys_domains, j);
|
|
if (j != first_cpu(sd->groups->cpumask)) {
|
|
/*
|
|
* Only add "power" once for each
|
|
* physical package.
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
sg->cpu_power += sd->groups->cpu_power;
|
|
}
|
|
sg = sg->next;
|
|
if (sg != group_head)
|
|
goto next_sg;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/* Free memory allocated for various sched_group structures */
|
|
static void free_sched_groups(const cpumask_t *cpu_map)
|
|
{
|
|
int cpu, i;
|
|
|
|
for_each_cpu_mask(cpu, *cpu_map) {
|
|
struct sched_group **sched_group_nodes
|
|
= sched_group_nodes_bycpu[cpu];
|
|
|
|
if (!sched_group_nodes)
|
|
continue;
|
|
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
cpumask_t nodemask = node_to_cpumask(i);
|
|
struct sched_group *oldsg, *sg = sched_group_nodes[i];
|
|
|
|
cpus_and(nodemask, nodemask, *cpu_map);
|
|
if (cpus_empty(nodemask))
|
|
continue;
|
|
|
|
if (sg == NULL)
|
|
continue;
|
|
sg = sg->next;
|
|
next_sg:
|
|
oldsg = sg;
|
|
sg = sg->next;
|
|
kfree(oldsg);
|
|
if (oldsg != sched_group_nodes[i])
|
|
goto next_sg;
|
|
}
|
|
kfree(sched_group_nodes);
|
|
sched_group_nodes_bycpu[cpu] = NULL;
|
|
}
|
|
}
|
|
#else
|
|
static void free_sched_groups(const cpumask_t *cpu_map)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Initialize sched groups cpu_power.
|
|
*
|
|
* cpu_power indicates the capacity of sched group, which is used while
|
|
* distributing the load between different sched groups in a sched domain.
|
|
* Typically cpu_power for all the groups in a sched domain will be same unless
|
|
* there are asymmetries in the topology. If there are asymmetries, group
|
|
* having more cpu_power will pickup more load compared to the group having
|
|
* less cpu_power.
|
|
*
|
|
* cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
|
|
* the maximum number of tasks a group can handle in the presence of other idle
|
|
* or lightly loaded groups in the same sched domain.
|
|
*/
|
|
static void init_sched_groups_power(int cpu, struct sched_domain *sd)
|
|
{
|
|
struct sched_domain *child;
|
|
struct sched_group *group;
|
|
|
|
WARN_ON(!sd || !sd->groups);
|
|
|
|
if (cpu != first_cpu(sd->groups->cpumask))
|
|
return;
|
|
|
|
child = sd->child;
|
|
|
|
/*
|
|
* For perf policy, if the groups in child domain share resources
|
|
* (for example cores sharing some portions of the cache hierarchy
|
|
* or SMT), then set this domain groups cpu_power such that each group
|
|
* can handle only one task, when there are other idle groups in the
|
|
* same sched domain.
|
|
*/
|
|
if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
|
|
(child->flags &
|
|
(SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
|
|
sd->groups->cpu_power = SCHED_LOAD_SCALE;
|
|
return;
|
|
}
|
|
|
|
sd->groups->cpu_power = 0;
|
|
|
|
/*
|
|
* add cpu_power of each child group to this groups cpu_power
|
|
*/
|
|
group = child->groups;
|
|
do {
|
|
sd->groups->cpu_power += group->cpu_power;
|
|
group = group->next;
|
|
} while (group != child->groups);
|
|
}
|
|
|
|
/*
|
|
* Build sched domains for a given set of cpus and attach the sched domains
|
|
* to the individual cpus
|
|
*/
|
|
static int build_sched_domains(const cpumask_t *cpu_map)
|
|
{
|
|
int i;
|
|
struct sched_domain *sd;
|
|
#ifdef CONFIG_NUMA
|
|
struct sched_group **sched_group_nodes = NULL;
|
|
int sd_allnodes = 0;
|
|
|
|
/*
|
|
* Allocate the per-node list of sched groups
|
|
*/
|
|
sched_group_nodes = kzalloc(sizeof(struct sched_group*)*MAX_NUMNODES,
|
|
GFP_KERNEL);
|
|
if (!sched_group_nodes) {
|
|
printk(KERN_WARNING "Can not alloc sched group node list\n");
|
|
return -ENOMEM;
|
|
}
|
|
sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
|
|
#endif
|
|
|
|
/*
|
|
* Set up domains for cpus specified by the cpu_map.
|
|
*/
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
struct sched_domain *sd = NULL, *p;
|
|
cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
|
|
|
|
cpus_and(nodemask, nodemask, *cpu_map);
|
|
|
|
#ifdef CONFIG_NUMA
|
|
if (cpus_weight(*cpu_map)
|
|
> SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
|
|
sd = &per_cpu(allnodes_domains, i);
|
|
*sd = SD_ALLNODES_INIT;
|
|
sd->span = *cpu_map;
|
|
cpu_to_allnodes_group(i, cpu_map, &sd->groups);
|
|
p = sd;
|
|
sd_allnodes = 1;
|
|
} else
|
|
p = NULL;
|
|
|
|
sd = &per_cpu(node_domains, i);
|
|
*sd = SD_NODE_INIT;
|
|
sd->span = sched_domain_node_span(cpu_to_node(i));
|
|
sd->parent = p;
|
|
if (p)
|
|
p->child = sd;
|
|
cpus_and(sd->span, sd->span, *cpu_map);
|
|
#endif
|
|
|
|
p = sd;
|
|
sd = &per_cpu(phys_domains, i);
|
|
*sd = SD_CPU_INIT;
|
|
sd->span = nodemask;
|
|
sd->parent = p;
|
|
if (p)
|
|
p->child = sd;
|
|
cpu_to_phys_group(i, cpu_map, &sd->groups);
|
|
|
|
#ifdef CONFIG_SCHED_MC
|
|
p = sd;
|
|
sd = &per_cpu(core_domains, i);
|
|
*sd = SD_MC_INIT;
|
|
sd->span = cpu_coregroup_map(i);
|
|
cpus_and(sd->span, sd->span, *cpu_map);
|
|
sd->parent = p;
|
|
p->child = sd;
|
|
cpu_to_core_group(i, cpu_map, &sd->groups);
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
p = sd;
|
|
sd = &per_cpu(cpu_domains, i);
|
|
*sd = SD_SIBLING_INIT;
|
|
sd->span = cpu_sibling_map[i];
|
|
cpus_and(sd->span, sd->span, *cpu_map);
|
|
sd->parent = p;
|
|
p->child = sd;
|
|
cpu_to_cpu_group(i, cpu_map, &sd->groups);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
/* Set up CPU (sibling) groups */
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
cpumask_t this_sibling_map = cpu_sibling_map[i];
|
|
cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
|
|
if (i != first_cpu(this_sibling_map))
|
|
continue;
|
|
|
|
init_sched_build_groups(this_sibling_map, cpu_map, &cpu_to_cpu_group);
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_MC
|
|
/* Set up multi-core groups */
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
cpumask_t this_core_map = cpu_coregroup_map(i);
|
|
cpus_and(this_core_map, this_core_map, *cpu_map);
|
|
if (i != first_cpu(this_core_map))
|
|
continue;
|
|
init_sched_build_groups(this_core_map, cpu_map, &cpu_to_core_group);
|
|
}
|
|
#endif
|
|
|
|
|
|
/* Set up physical groups */
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
cpumask_t nodemask = node_to_cpumask(i);
|
|
|
|
cpus_and(nodemask, nodemask, *cpu_map);
|
|
if (cpus_empty(nodemask))
|
|
continue;
|
|
|
|
init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
/* Set up node groups */
|
|
if (sd_allnodes)
|
|
init_sched_build_groups(*cpu_map, cpu_map, &cpu_to_allnodes_group);
|
|
|
|
for (i = 0; i < MAX_NUMNODES; i++) {
|
|
/* Set up node groups */
|
|
struct sched_group *sg, *prev;
|
|
cpumask_t nodemask = node_to_cpumask(i);
|
|
cpumask_t domainspan;
|
|
cpumask_t covered = CPU_MASK_NONE;
|
|
int j;
|
|
|
|
cpus_and(nodemask, nodemask, *cpu_map);
|
|
if (cpus_empty(nodemask)) {
|
|
sched_group_nodes[i] = NULL;
|
|
continue;
|
|
}
|
|
|
|
domainspan = sched_domain_node_span(i);
|
|
cpus_and(domainspan, domainspan, *cpu_map);
|
|
|
|
sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
|
|
if (!sg) {
|
|
printk(KERN_WARNING "Can not alloc domain group for "
|
|
"node %d\n", i);
|
|
goto error;
|
|
}
|
|
sched_group_nodes[i] = sg;
|
|
for_each_cpu_mask(j, nodemask) {
|
|
struct sched_domain *sd;
|
|
sd = &per_cpu(node_domains, j);
|
|
sd->groups = sg;
|
|
}
|
|
sg->cpu_power = 0;
|
|
sg->cpumask = nodemask;
|
|
sg->next = sg;
|
|
cpus_or(covered, covered, nodemask);
|
|
prev = sg;
|
|
|
|
for (j = 0; j < MAX_NUMNODES; j++) {
|
|
cpumask_t tmp, notcovered;
|
|
int n = (i + j) % MAX_NUMNODES;
|
|
|
|
cpus_complement(notcovered, covered);
|
|
cpus_and(tmp, notcovered, *cpu_map);
|
|
cpus_and(tmp, tmp, domainspan);
|
|
if (cpus_empty(tmp))
|
|
break;
|
|
|
|
nodemask = node_to_cpumask(n);
|
|
cpus_and(tmp, tmp, nodemask);
|
|
if (cpus_empty(tmp))
|
|
continue;
|
|
|
|
sg = kmalloc_node(sizeof(struct sched_group),
|
|
GFP_KERNEL, i);
|
|
if (!sg) {
|
|
printk(KERN_WARNING
|
|
"Can not alloc domain group for node %d\n", j);
|
|
goto error;
|
|
}
|
|
sg->cpu_power = 0;
|
|
sg->cpumask = tmp;
|
|
sg->next = prev->next;
|
|
cpus_or(covered, covered, tmp);
|
|
prev->next = sg;
|
|
prev = sg;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* Calculate CPU power for physical packages and nodes */
|
|
#ifdef CONFIG_SCHED_SMT
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
sd = &per_cpu(cpu_domains, i);
|
|
init_sched_groups_power(i, sd);
|
|
}
|
|
#endif
|
|
#ifdef CONFIG_SCHED_MC
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
sd = &per_cpu(core_domains, i);
|
|
init_sched_groups_power(i, sd);
|
|
}
|
|
#endif
|
|
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
sd = &per_cpu(phys_domains, i);
|
|
init_sched_groups_power(i, sd);
|
|
}
|
|
|
|
#ifdef CONFIG_NUMA
|
|
for (i = 0; i < MAX_NUMNODES; i++)
|
|
init_numa_sched_groups_power(sched_group_nodes[i]);
|
|
|
|
if (sd_allnodes) {
|
|
struct sched_group *sg;
|
|
|
|
cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg);
|
|
init_numa_sched_groups_power(sg);
|
|
}
|
|
#endif
|
|
|
|
/* Attach the domains */
|
|
for_each_cpu_mask(i, *cpu_map) {
|
|
struct sched_domain *sd;
|
|
#ifdef CONFIG_SCHED_SMT
|
|
sd = &per_cpu(cpu_domains, i);
|
|
#elif defined(CONFIG_SCHED_MC)
|
|
sd = &per_cpu(core_domains, i);
|
|
#else
|
|
sd = &per_cpu(phys_domains, i);
|
|
#endif
|
|
cpu_attach_domain(sd, i);
|
|
}
|
|
/*
|
|
* Tune cache-hot values:
|
|
*/
|
|
calibrate_migration_costs(cpu_map);
|
|
|
|
return 0;
|
|
|
|
#ifdef CONFIG_NUMA
|
|
error:
|
|
free_sched_groups(cpu_map);
|
|
return -ENOMEM;
|
|
#endif
|
|
}
|
|
/*
|
|
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
|
|
*/
|
|
static int arch_init_sched_domains(const cpumask_t *cpu_map)
|
|
{
|
|
cpumask_t cpu_default_map;
|
|
int err;
|
|
|
|
/*
|
|
* Setup mask for cpus without special case scheduling requirements.
|
|
* For now this just excludes isolated cpus, but could be used to
|
|
* exclude other special cases in the future.
|
|
*/
|
|
cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
|
|
|
|
err = build_sched_domains(&cpu_default_map);
|
|
|
|
return err;
|
|
}
|
|
|
|
static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
|
|
{
|
|
free_sched_groups(cpu_map);
|
|
}
|
|
|
|
/*
|
|
* Detach sched domains from a group of cpus specified in cpu_map
|
|
* These cpus will now be attached to the NULL domain
|
|
*/
|
|
static void detach_destroy_domains(const cpumask_t *cpu_map)
|
|
{
|
|
int i;
|
|
|
|
for_each_cpu_mask(i, *cpu_map)
|
|
cpu_attach_domain(NULL, i);
|
|
synchronize_sched();
|
|
arch_destroy_sched_domains(cpu_map);
|
|
}
|
|
|
|
/*
|
|
* Partition sched domains as specified by the cpumasks below.
|
|
* This attaches all cpus from the cpumasks to the NULL domain,
|
|
* waits for a RCU quiescent period, recalculates sched
|
|
* domain information and then attaches them back to the
|
|
* correct sched domains
|
|
* Call with hotplug lock held
|
|
*/
|
|
int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
|
|
{
|
|
cpumask_t change_map;
|
|
int err = 0;
|
|
|
|
cpus_and(*partition1, *partition1, cpu_online_map);
|
|
cpus_and(*partition2, *partition2, cpu_online_map);
|
|
cpus_or(change_map, *partition1, *partition2);
|
|
|
|
/* Detach sched domains from all of the affected cpus */
|
|
detach_destroy_domains(&change_map);
|
|
if (!cpus_empty(*partition1))
|
|
err = build_sched_domains(partition1);
|
|
if (!err && !cpus_empty(*partition2))
|
|
err = build_sched_domains(partition2);
|
|
|
|
return err;
|
|
}
|
|
|
|
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
|
|
int arch_reinit_sched_domains(void)
|
|
{
|
|
int err;
|
|
|
|
lock_cpu_hotplug();
|
|
detach_destroy_domains(&cpu_online_map);
|
|
err = arch_init_sched_domains(&cpu_online_map);
|
|
unlock_cpu_hotplug();
|
|
|
|
return err;
|
|
}
|
|
|
|
static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
|
|
{
|
|
int ret;
|
|
|
|
if (buf[0] != '0' && buf[0] != '1')
|
|
return -EINVAL;
|
|
|
|
if (smt)
|
|
sched_smt_power_savings = (buf[0] == '1');
|
|
else
|
|
sched_mc_power_savings = (buf[0] == '1');
|
|
|
|
ret = arch_reinit_sched_domains();
|
|
|
|
return ret ? ret : count;
|
|
}
|
|
|
|
int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
|
|
{
|
|
int err = 0;
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
if (smt_capable())
|
|
err = sysfs_create_file(&cls->kset.kobj,
|
|
&attr_sched_smt_power_savings.attr);
|
|
#endif
|
|
#ifdef CONFIG_SCHED_MC
|
|
if (!err && mc_capable())
|
|
err = sysfs_create_file(&cls->kset.kobj,
|
|
&attr_sched_mc_power_savings.attr);
|
|
#endif
|
|
return err;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_MC
|
|
static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
|
|
{
|
|
return sprintf(page, "%u\n", sched_mc_power_savings);
|
|
}
|
|
static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
|
|
const char *buf, size_t count)
|
|
{
|
|
return sched_power_savings_store(buf, count, 0);
|
|
}
|
|
SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
|
|
sched_mc_power_savings_store);
|
|
#endif
|
|
|
|
#ifdef CONFIG_SCHED_SMT
|
|
static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
|
|
{
|
|
return sprintf(page, "%u\n", sched_smt_power_savings);
|
|
}
|
|
static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
|
|
const char *buf, size_t count)
|
|
{
|
|
return sched_power_savings_store(buf, count, 1);
|
|
}
|
|
SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
|
|
sched_smt_power_savings_store);
|
|
#endif
|
|
|
|
/*
|
|
* Force a reinitialization of the sched domains hierarchy. The domains
|
|
* and groups cannot be updated in place without racing with the balancing
|
|
* code, so we temporarily attach all running cpus to the NULL domain
|
|
* which will prevent rebalancing while the sched domains are recalculated.
|
|
*/
|
|
static int update_sched_domains(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
case CPU_DOWN_PREPARE:
|
|
detach_destroy_domains(&cpu_online_map);
|
|
return NOTIFY_OK;
|
|
|
|
case CPU_UP_CANCELED:
|
|
case CPU_DOWN_FAILED:
|
|
case CPU_ONLINE:
|
|
case CPU_DEAD:
|
|
/*
|
|
* Fall through and re-initialise the domains.
|
|
*/
|
|
break;
|
|
default:
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
/* The hotplug lock is already held by cpu_up/cpu_down */
|
|
arch_init_sched_domains(&cpu_online_map);
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
void __init sched_init_smp(void)
|
|
{
|
|
cpumask_t non_isolated_cpus;
|
|
|
|
lock_cpu_hotplug();
|
|
arch_init_sched_domains(&cpu_online_map);
|
|
cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
|
|
if (cpus_empty(non_isolated_cpus))
|
|
cpu_set(smp_processor_id(), non_isolated_cpus);
|
|
unlock_cpu_hotplug();
|
|
/* XXX: Theoretical race here - CPU may be hotplugged now */
|
|
hotcpu_notifier(update_sched_domains, 0);
|
|
|
|
/* Move init over to a non-isolated CPU */
|
|
if (set_cpus_allowed(current, non_isolated_cpus) < 0)
|
|
BUG();
|
|
}
|
|
#else
|
|
void __init sched_init_smp(void)
|
|
{
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
int in_sched_functions(unsigned long addr)
|
|
{
|
|
/* Linker adds these: start and end of __sched functions */
|
|
extern char __sched_text_start[], __sched_text_end[];
|
|
|
|
return in_lock_functions(addr) ||
|
|
(addr >= (unsigned long)__sched_text_start
|
|
&& addr < (unsigned long)__sched_text_end);
|
|
}
|
|
|
|
void __init sched_init(void)
|
|
{
|
|
int i, j, k;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct prio_array *array;
|
|
struct rq *rq;
|
|
|
|
rq = cpu_rq(i);
|
|
spin_lock_init(&rq->lock);
|
|
lockdep_set_class(&rq->lock, &rq->rq_lock_key);
|
|
rq->nr_running = 0;
|
|
rq->active = rq->arrays;
|
|
rq->expired = rq->arrays + 1;
|
|
rq->best_expired_prio = MAX_PRIO;
|
|
|
|
#ifdef CONFIG_SMP
|
|
rq->sd = NULL;
|
|
for (j = 1; j < 3; j++)
|
|
rq->cpu_load[j] = 0;
|
|
rq->active_balance = 0;
|
|
rq->push_cpu = 0;
|
|
rq->cpu = i;
|
|
rq->migration_thread = NULL;
|
|
INIT_LIST_HEAD(&rq->migration_queue);
|
|
#endif
|
|
atomic_set(&rq->nr_iowait, 0);
|
|
|
|
for (j = 0; j < 2; j++) {
|
|
array = rq->arrays + j;
|
|
for (k = 0; k < MAX_PRIO; k++) {
|
|
INIT_LIST_HEAD(array->queue + k);
|
|
__clear_bit(k, array->bitmap);
|
|
}
|
|
// delimiter for bitsearch
|
|
__set_bit(MAX_PRIO, array->bitmap);
|
|
}
|
|
}
|
|
|
|
set_load_weight(&init_task);
|
|
|
|
#ifdef CONFIG_SMP
|
|
open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
|
|
#endif
|
|
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
|
|
#endif
|
|
|
|
/*
|
|
* The boot idle thread does lazy MMU switching as well:
|
|
*/
|
|
atomic_inc(&init_mm.mm_count);
|
|
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());
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
|
|
void __might_sleep(char *file, int line)
|
|
{
|
|
#ifdef in_atomic
|
|
static unsigned long prev_jiffy; /* ratelimiting */
|
|
|
|
if ((in_atomic() || irqs_disabled()) &&
|
|
system_state == SYSTEM_RUNNING && !oops_in_progress) {
|
|
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
|
|
return;
|
|
prev_jiffy = jiffies;
|
|
printk(KERN_ERR "BUG: sleeping function called from invalid"
|
|
" context at %s:%d\n", file, line);
|
|
printk("in_atomic():%d, irqs_disabled():%d\n",
|
|
in_atomic(), irqs_disabled());
|
|
debug_show_held_locks(current);
|
|
if (irqs_disabled())
|
|
print_irqtrace_events(current);
|
|
dump_stack();
|
|
}
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(__might_sleep);
|
|
#endif
|
|
|
|
#ifdef CONFIG_MAGIC_SYSRQ
|
|
void normalize_rt_tasks(void)
|
|
{
|
|
struct prio_array *array;
|
|
struct task_struct *p;
|
|
unsigned long flags;
|
|
struct rq *rq;
|
|
|
|
read_lock_irq(&tasklist_lock);
|
|
for_each_process(p) {
|
|
if (!rt_task(p))
|
|
continue;
|
|
|
|
spin_lock_irqsave(&p->pi_lock, flags);
|
|
rq = __task_rq_lock(p);
|
|
|
|
array = p->array;
|
|
if (array)
|
|
deactivate_task(p, task_rq(p));
|
|
__setscheduler(p, SCHED_NORMAL, 0);
|
|
if (array) {
|
|
__activate_task(p, task_rq(p));
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
__task_rq_unlock(rq);
|
|
spin_unlock_irqrestore(&p->pi_lock, flags);
|
|
}
|
|
read_unlock_irq(&tasklist_lock);
|
|
}
|
|
|
|
#endif /* CONFIG_MAGIC_SYSRQ */
|
|
|
|
#ifdef CONFIG_IA64
|
|
/*
|
|
* These functions are only useful for the IA64 MCA handling.
|
|
*
|
|
* 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!
|
|
*/
|
|
struct task_struct *curr_task(int cpu)
|
|
{
|
|
return cpu_curr(cpu);
|
|
}
|
|
|
|
/**
|
|
* 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 set_curr_task(int cpu, struct task_struct *p)
|
|
{
|
|
cpu_curr(cpu) = p;
|
|
}
|
|
|
|
#endif
|