161 lines
3.5 KiB
C
161 lines
3.5 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2019 Intel Corporation
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*/
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include "i915_active.h"
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#include "gem/i915_gem_context.h"
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#include "gem/i915_gem_object.h"
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#include "i915_globals.h"
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#include "i915_request.h"
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#include "i915_scheduler.h"
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#include "i915_vma.h"
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static LIST_HEAD(globals);
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static atomic_t active;
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static atomic_t epoch;
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static struct park_work {
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struct delayed_work work;
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struct rcu_head rcu;
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unsigned long flags;
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#define PENDING 0
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int epoch;
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} park;
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static void i915_globals_shrink(void)
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{
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struct i915_global *global;
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/*
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* kmem_cache_shrink() discards empty slabs and reorders partially
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* filled slabs to prioritise allocating from the mostly full slabs,
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* with the aim of reducing fragmentation.
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*/
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list_for_each_entry(global, &globals, link)
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global->shrink();
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}
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static void __i915_globals_grace(struct rcu_head *rcu)
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{
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/* Ratelimit parking as shrinking is quite slow */
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schedule_delayed_work(&park.work, round_jiffies_up_relative(2 * HZ));
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}
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static void __i915_globals_queue_rcu(void)
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{
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park.epoch = atomic_inc_return(&epoch);
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if (!atomic_read(&active)) {
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init_rcu_head(&park.rcu);
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call_rcu(&park.rcu, __i915_globals_grace);
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}
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}
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static void __i915_globals_park(struct work_struct *work)
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{
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destroy_rcu_head(&park.rcu);
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/* Confirm nothing woke up in the last grace period */
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if (park.epoch != atomic_read(&epoch)) {
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__i915_globals_queue_rcu();
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return;
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}
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clear_bit(PENDING, &park.flags);
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i915_globals_shrink();
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}
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void __init i915_global_register(struct i915_global *global)
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{
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GEM_BUG_ON(!global->shrink);
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GEM_BUG_ON(!global->exit);
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list_add_tail(&global->link, &globals);
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}
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static void __i915_globals_cleanup(void)
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{
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struct i915_global *global, *next;
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list_for_each_entry_safe_reverse(global, next, &globals, link)
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global->exit();
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}
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static __initconst int (* const initfn[])(void) = {
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i915_global_active_init,
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i915_global_context_init,
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i915_global_gem_context_init,
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i915_global_objects_init,
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i915_global_request_init,
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i915_global_scheduler_init,
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i915_global_vma_init,
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};
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int __init i915_globals_init(void)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(initfn); i++) {
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int err;
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err = initfn[i]();
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if (err) {
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__i915_globals_cleanup();
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return err;
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}
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}
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INIT_DELAYED_WORK(&park.work, __i915_globals_park);
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return 0;
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}
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void i915_globals_park(void)
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{
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/*
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* Defer shrinking the global slab caches (and other work) until
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* after a RCU grace period has completed with no activity. This
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* is to try and reduce the latency impact on the consumers caused
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* by us shrinking the caches the same time as they are trying to
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* allocate, with the assumption being that if we idle long enough
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* for an RCU grace period to elapse since the last use, it is likely
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* to be longer until we need the caches again.
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*/
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if (!atomic_dec_and_test(&active))
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return;
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/* Queue cleanup after the next RCU grace period has freed slabs */
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if (!test_and_set_bit(PENDING, &park.flags))
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__i915_globals_queue_rcu();
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}
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void i915_globals_unpark(void)
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{
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atomic_inc(&epoch);
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atomic_inc(&active);
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}
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static void __exit __i915_globals_flush(void)
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{
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atomic_inc(&active); /* skip shrinking */
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rcu_barrier(); /* wait for the work to be queued */
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flush_delayed_work(&park.work);
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atomic_dec(&active);
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}
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void __exit i915_globals_exit(void)
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{
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GEM_BUG_ON(atomic_read(&active));
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__i915_globals_flush();
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__i915_globals_cleanup();
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/* And ensure that our DESTROY_BY_RCU slabs are truly destroyed */
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rcu_barrier();
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}
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