4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/ctype.h>
70 #include <linux/ftrace.h>
71 #include <linux/slab.h>
72 #include <linux/init_task.h>
73 #include <linux/context_tracking.h>
74 #include <linux/compiler.h>
76 #include <asm/switch_to.h>
78 #include <asm/irq_regs.h>
79 #include <asm/mutex.h>
80 #ifdef CONFIG_PARAVIRT
81 #include <asm/paravirt.h>
85 #include "../workqueue_internal.h"
86 #include "../smpboot.h"
88 #define CREATE_TRACE_POINTS
89 #include <trace/events/sched.h>
91 DEFINE_MUTEX(sched_domains_mutex);
92 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
94 static void update_rq_clock_task(struct rq *rq, s64 delta);
96 void update_rq_clock(struct rq *rq)
100 lockdep_assert_held(&rq->lock);
102 if (rq->clock_skip_update & RQCF_ACT_SKIP)
105 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
109 update_rq_clock_task(rq, delta);
113 * Debugging: various feature bits
116 #define SCHED_FEAT(name, enabled) \
117 (1UL << __SCHED_FEAT_##name) * enabled |
119 const_debug unsigned int sysctl_sched_features =
120 #include "features.h"
126 * Number of tasks to iterate in a single balance run.
127 * Limited because this is done with IRQs disabled.
129 const_debug unsigned int sysctl_sched_nr_migrate = 32;
132 * period over which we average the RT time consumption, measured
137 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
140 * period over which we measure -rt task cpu usage in us.
143 unsigned int sysctl_sched_rt_period = 1000000;
145 __read_mostly int scheduler_running;
148 * part of the period that we allow rt tasks to run in us.
151 int sysctl_sched_rt_runtime = 950000;
153 /* cpus with isolated domains */
154 cpumask_var_t cpu_isolated_map;
157 * this_rq_lock - lock this runqueue and disable interrupts.
159 static struct rq *this_rq_lock(void)
166 raw_spin_lock(&rq->lock);
171 #ifdef CONFIG_SCHED_HRTICK
173 * Use HR-timers to deliver accurate preemption points.
176 static void hrtick_clear(struct rq *rq)
178 if (hrtimer_active(&rq->hrtick_timer))
179 hrtimer_cancel(&rq->hrtick_timer);
183 * High-resolution timer tick.
184 * Runs from hardirq context with interrupts disabled.
186 static enum hrtimer_restart hrtick(struct hrtimer *timer)
188 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
190 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
192 raw_spin_lock(&rq->lock);
194 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
195 raw_spin_unlock(&rq->lock);
197 return HRTIMER_NORESTART;
202 static void __hrtick_restart(struct rq *rq)
204 struct hrtimer *timer = &rq->hrtick_timer;
206 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
210 * called from hardirq (IPI) context
212 static void __hrtick_start(void *arg)
216 raw_spin_lock(&rq->lock);
217 __hrtick_restart(rq);
218 rq->hrtick_csd_pending = 0;
219 raw_spin_unlock(&rq->lock);
223 * Called to set the hrtick timer state.
225 * called with rq->lock held and irqs disabled
227 void hrtick_start(struct rq *rq, u64 delay)
229 struct hrtimer *timer = &rq->hrtick_timer;
234 * Don't schedule slices shorter than 10000ns, that just
235 * doesn't make sense and can cause timer DoS.
237 delta = max_t(s64, delay, 10000LL);
238 time = ktime_add_ns(timer->base->get_time(), delta);
240 hrtimer_set_expires(timer, time);
242 if (rq == this_rq()) {
243 __hrtick_restart(rq);
244 } else if (!rq->hrtick_csd_pending) {
245 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
246 rq->hrtick_csd_pending = 1;
251 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
253 int cpu = (int)(long)hcpu;
256 case CPU_UP_CANCELED:
257 case CPU_UP_CANCELED_FROZEN:
258 case CPU_DOWN_PREPARE:
259 case CPU_DOWN_PREPARE_FROZEN:
261 case CPU_DEAD_FROZEN:
262 hrtick_clear(cpu_rq(cpu));
269 static __init void init_hrtick(void)
271 hotcpu_notifier(hotplug_hrtick, 0);
275 * Called to set the hrtick timer state.
277 * called with rq->lock held and irqs disabled
279 void hrtick_start(struct rq *rq, u64 delay)
282 * Don't schedule slices shorter than 10000ns, that just
283 * doesn't make sense. Rely on vruntime for fairness.
285 delay = max_t(u64, delay, 10000LL);
286 hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
287 HRTIMER_MODE_REL_PINNED);
290 static inline void init_hrtick(void)
293 #endif /* CONFIG_SMP */
295 static void init_rq_hrtick(struct rq *rq)
298 rq->hrtick_csd_pending = 0;
300 rq->hrtick_csd.flags = 0;
301 rq->hrtick_csd.func = __hrtick_start;
302 rq->hrtick_csd.info = rq;
305 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
306 rq->hrtick_timer.function = hrtick;
308 #else /* CONFIG_SCHED_HRTICK */
309 static inline void hrtick_clear(struct rq *rq)
313 static inline void init_rq_hrtick(struct rq *rq)
317 static inline void init_hrtick(void)
320 #endif /* CONFIG_SCHED_HRTICK */
323 * cmpxchg based fetch_or, macro so it works for different integer types
325 #define fetch_or(ptr, val) \
326 ({ typeof(*(ptr)) __old, __val = *(ptr); \
328 __old = cmpxchg((ptr), __val, __val | (val)); \
329 if (__old == __val) \
336 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
338 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
339 * this avoids any races wrt polling state changes and thereby avoids
342 static bool set_nr_and_not_polling(struct task_struct *p)
344 struct thread_info *ti = task_thread_info(p);
345 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
349 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
351 * If this returns true, then the idle task promises to call
352 * sched_ttwu_pending() and reschedule soon.
354 static bool set_nr_if_polling(struct task_struct *p)
356 struct thread_info *ti = task_thread_info(p);
357 typeof(ti->flags) old, val = READ_ONCE(ti->flags);
360 if (!(val & _TIF_POLLING_NRFLAG))
362 if (val & _TIF_NEED_RESCHED)
364 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
373 static bool set_nr_and_not_polling(struct task_struct *p)
375 set_tsk_need_resched(p);
380 static bool set_nr_if_polling(struct task_struct *p)
387 void wake_q_add(struct wake_q_head *head, struct task_struct *task)
389 struct wake_q_node *node = &task->wake_q;
392 * Atomically grab the task, if ->wake_q is !nil already it means
393 * its already queued (either by us or someone else) and will get the
394 * wakeup due to that.
396 * This cmpxchg() implies a full barrier, which pairs with the write
397 * barrier implied by the wakeup in wake_up_list().
399 if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
402 get_task_struct(task);
405 * The head is context local, there can be no concurrency.
408 head->lastp = &node->next;
411 void wake_up_q(struct wake_q_head *head)
413 struct wake_q_node *node = head->first;
415 while (node != WAKE_Q_TAIL) {
416 struct task_struct *task;
418 task = container_of(node, struct task_struct, wake_q);
420 /* task can safely be re-inserted now */
422 task->wake_q.next = NULL;
425 * wake_up_process() implies a wmb() to pair with the queueing
426 * in wake_q_add() so as not to miss wakeups.
428 wake_up_process(task);
429 put_task_struct(task);
434 * resched_curr - mark rq's current task 'to be rescheduled now'.
436 * On UP this means the setting of the need_resched flag, on SMP it
437 * might also involve a cross-CPU call to trigger the scheduler on
440 void resched_curr(struct rq *rq)
442 struct task_struct *curr = rq->curr;
445 lockdep_assert_held(&rq->lock);
447 if (test_tsk_need_resched(curr))
452 if (cpu == smp_processor_id()) {
453 set_tsk_need_resched(curr);
454 set_preempt_need_resched();
458 if (set_nr_and_not_polling(curr))
459 smp_send_reschedule(cpu);
461 trace_sched_wake_idle_without_ipi(cpu);
464 void resched_cpu(int cpu)
466 struct rq *rq = cpu_rq(cpu);
469 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
472 raw_spin_unlock_irqrestore(&rq->lock, flags);
476 #ifdef CONFIG_NO_HZ_COMMON
478 * In the semi idle case, use the nearest busy cpu for migrating timers
479 * from an idle cpu. This is good for power-savings.
481 * We don't do similar optimization for completely idle system, as
482 * selecting an idle cpu will add more delays to the timers than intended
483 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
485 int get_nohz_timer_target(void)
487 int i, cpu = smp_processor_id();
488 struct sched_domain *sd;
490 if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
494 for_each_domain(cpu, sd) {
495 for_each_cpu(i, sched_domain_span(sd)) {
496 if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
503 if (!is_housekeeping_cpu(cpu))
504 cpu = housekeeping_any_cpu();
510 * When add_timer_on() enqueues a timer into the timer wheel of an
511 * idle CPU then this timer might expire before the next timer event
512 * which is scheduled to wake up that CPU. In case of a completely
513 * idle system the next event might even be infinite time into the
514 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
515 * leaves the inner idle loop so the newly added timer is taken into
516 * account when the CPU goes back to idle and evaluates the timer
517 * wheel for the next timer event.
519 static void wake_up_idle_cpu(int cpu)
521 struct rq *rq = cpu_rq(cpu);
523 if (cpu == smp_processor_id())
526 if (set_nr_and_not_polling(rq->idle))
527 smp_send_reschedule(cpu);
529 trace_sched_wake_idle_without_ipi(cpu);
532 static bool wake_up_full_nohz_cpu(int cpu)
535 * We just need the target to call irq_exit() and re-evaluate
536 * the next tick. The nohz full kick at least implies that.
537 * If needed we can still optimize that later with an
540 if (tick_nohz_full_cpu(cpu)) {
541 if (cpu != smp_processor_id() ||
542 tick_nohz_tick_stopped())
543 tick_nohz_full_kick_cpu(cpu);
550 void wake_up_nohz_cpu(int cpu)
552 if (!wake_up_full_nohz_cpu(cpu))
553 wake_up_idle_cpu(cpu);
556 static inline bool got_nohz_idle_kick(void)
558 int cpu = smp_processor_id();
560 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
563 if (idle_cpu(cpu) && !need_resched())
567 * We can't run Idle Load Balance on this CPU for this time so we
568 * cancel it and clear NOHZ_BALANCE_KICK
570 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
574 #else /* CONFIG_NO_HZ_COMMON */
576 static inline bool got_nohz_idle_kick(void)
581 #endif /* CONFIG_NO_HZ_COMMON */
583 #ifdef CONFIG_NO_HZ_FULL
584 bool sched_can_stop_tick(void)
587 * FIFO realtime policy runs the highest priority task. Other runnable
588 * tasks are of a lower priority. The scheduler tick does nothing.
590 if (current->policy == SCHED_FIFO)
594 * Round-robin realtime tasks time slice with other tasks at the same
595 * realtime priority. Is this task the only one at this priority?
597 if (current->policy == SCHED_RR) {
598 struct sched_rt_entity *rt_se = ¤t->rt;
600 return list_is_singular(&rt_se->run_list);
604 * More than one running task need preemption.
605 * nr_running update is assumed to be visible
606 * after IPI is sent from wakers.
608 if (this_rq()->nr_running > 1)
613 #endif /* CONFIG_NO_HZ_FULL */
615 void sched_avg_update(struct rq *rq)
617 s64 period = sched_avg_period();
619 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
621 * Inline assembly required to prevent the compiler
622 * optimising this loop into a divmod call.
623 * See __iter_div_u64_rem() for another example of this.
625 asm("" : "+rm" (rq->age_stamp));
626 rq->age_stamp += period;
631 #endif /* CONFIG_SMP */
633 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
634 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
636 * Iterate task_group tree rooted at *from, calling @down when first entering a
637 * node and @up when leaving it for the final time.
639 * Caller must hold rcu_lock or sufficient equivalent.
641 int walk_tg_tree_from(struct task_group *from,
642 tg_visitor down, tg_visitor up, void *data)
644 struct task_group *parent, *child;
650 ret = (*down)(parent, data);
653 list_for_each_entry_rcu(child, &parent->children, siblings) {
660 ret = (*up)(parent, data);
661 if (ret || parent == from)
665 parent = parent->parent;
672 int tg_nop(struct task_group *tg, void *data)
678 static void set_load_weight(struct task_struct *p)
680 int prio = p->static_prio - MAX_RT_PRIO;
681 struct load_weight *load = &p->se.load;
684 * SCHED_IDLE tasks get minimal weight:
686 if (idle_policy(p->policy)) {
687 load->weight = scale_load(WEIGHT_IDLEPRIO);
688 load->inv_weight = WMULT_IDLEPRIO;
692 load->weight = scale_load(sched_prio_to_weight[prio]);
693 load->inv_weight = sched_prio_to_wmult[prio];
696 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
699 if (!(flags & ENQUEUE_RESTORE))
700 sched_info_queued(rq, p);
701 p->sched_class->enqueue_task(rq, p, flags);
704 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
707 if (!(flags & DEQUEUE_SAVE))
708 sched_info_dequeued(rq, p);
709 p->sched_class->dequeue_task(rq, p, flags);
712 void activate_task(struct rq *rq, struct task_struct *p, int flags)
714 if (task_contributes_to_load(p))
715 rq->nr_uninterruptible--;
717 enqueue_task(rq, p, flags);
720 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
722 if (task_contributes_to_load(p))
723 rq->nr_uninterruptible++;
725 dequeue_task(rq, p, flags);
728 static void update_rq_clock_task(struct rq *rq, s64 delta)
731 * In theory, the compile should just see 0 here, and optimize out the call
732 * to sched_rt_avg_update. But I don't trust it...
734 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
735 s64 steal = 0, irq_delta = 0;
737 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
738 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
741 * Since irq_time is only updated on {soft,}irq_exit, we might run into
742 * this case when a previous update_rq_clock() happened inside a
745 * When this happens, we stop ->clock_task and only update the
746 * prev_irq_time stamp to account for the part that fit, so that a next
747 * update will consume the rest. This ensures ->clock_task is
750 * It does however cause some slight miss-attribution of {soft,}irq
751 * time, a more accurate solution would be to update the irq_time using
752 * the current rq->clock timestamp, except that would require using
755 if (irq_delta > delta)
758 rq->prev_irq_time += irq_delta;
761 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
762 if (static_key_false((¶virt_steal_rq_enabled))) {
763 steal = paravirt_steal_clock(cpu_of(rq));
764 steal -= rq->prev_steal_time_rq;
766 if (unlikely(steal > delta))
769 rq->prev_steal_time_rq += steal;
774 rq->clock_task += delta;
776 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
777 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
778 sched_rt_avg_update(rq, irq_delta + steal);
782 void sched_set_stop_task(int cpu, struct task_struct *stop)
784 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
785 struct task_struct *old_stop = cpu_rq(cpu)->stop;
789 * Make it appear like a SCHED_FIFO task, its something
790 * userspace knows about and won't get confused about.
792 * Also, it will make PI more or less work without too
793 * much confusion -- but then, stop work should not
794 * rely on PI working anyway.
796 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
798 stop->sched_class = &stop_sched_class;
801 cpu_rq(cpu)->stop = stop;
805 * Reset it back to a normal scheduling class so that
806 * it can die in pieces.
808 old_stop->sched_class = &rt_sched_class;
813 * __normal_prio - return the priority that is based on the static prio
815 static inline int __normal_prio(struct task_struct *p)
817 return p->static_prio;
821 * Calculate the expected normal priority: i.e. priority
822 * without taking RT-inheritance into account. Might be
823 * boosted by interactivity modifiers. Changes upon fork,
824 * setprio syscalls, and whenever the interactivity
825 * estimator recalculates.
827 static inline int normal_prio(struct task_struct *p)
831 if (task_has_dl_policy(p))
832 prio = MAX_DL_PRIO-1;
833 else if (task_has_rt_policy(p))
834 prio = MAX_RT_PRIO-1 - p->rt_priority;
836 prio = __normal_prio(p);
841 * Calculate the current priority, i.e. the priority
842 * taken into account by the scheduler. This value might
843 * be boosted by RT tasks, or might be boosted by
844 * interactivity modifiers. Will be RT if the task got
845 * RT-boosted. If not then it returns p->normal_prio.
847 static int effective_prio(struct task_struct *p)
849 p->normal_prio = normal_prio(p);
851 * If we are RT tasks or we were boosted to RT priority,
852 * keep the priority unchanged. Otherwise, update priority
853 * to the normal priority:
855 if (!rt_prio(p->prio))
856 return p->normal_prio;
861 * task_curr - is this task currently executing on a CPU?
862 * @p: the task in question.
864 * Return: 1 if the task is currently executing. 0 otherwise.
866 inline int task_curr(const struct task_struct *p)
868 return cpu_curr(task_cpu(p)) == p;
872 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
873 * use the balance_callback list if you want balancing.
875 * this means any call to check_class_changed() must be followed by a call to
876 * balance_callback().
878 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
879 const struct sched_class *prev_class,
882 if (prev_class != p->sched_class) {
883 if (prev_class->switched_from)
884 prev_class->switched_from(rq, p);
886 p->sched_class->switched_to(rq, p);
887 } else if (oldprio != p->prio || dl_task(p))
888 p->sched_class->prio_changed(rq, p, oldprio);
891 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
893 const struct sched_class *class;
895 if (p->sched_class == rq->curr->sched_class) {
896 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
898 for_each_class(class) {
899 if (class == rq->curr->sched_class)
901 if (class == p->sched_class) {
909 * A queue event has occurred, and we're going to schedule. In
910 * this case, we can save a useless back to back clock update.
912 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
913 rq_clock_skip_update(rq, true);
918 * This is how migration works:
920 * 1) we invoke migration_cpu_stop() on the target CPU using
922 * 2) stopper starts to run (implicitly forcing the migrated thread
924 * 3) it checks whether the migrated task is still in the wrong runqueue.
925 * 4) if it's in the wrong runqueue then the migration thread removes
926 * it and puts it into the right queue.
927 * 5) stopper completes and stop_one_cpu() returns and the migration
932 * move_queued_task - move a queued task to new rq.
934 * Returns (locked) new rq. Old rq's lock is released.
936 static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
938 lockdep_assert_held(&rq->lock);
940 p->on_rq = TASK_ON_RQ_MIGRATING;
941 dequeue_task(rq, p, 0);
942 set_task_cpu(p, new_cpu);
943 raw_spin_unlock(&rq->lock);
945 rq = cpu_rq(new_cpu);
947 raw_spin_lock(&rq->lock);
948 BUG_ON(task_cpu(p) != new_cpu);
949 enqueue_task(rq, p, 0);
950 p->on_rq = TASK_ON_RQ_QUEUED;
951 check_preempt_curr(rq, p, 0);
956 struct migration_arg {
957 struct task_struct *task;
962 * Move (not current) task off this cpu, onto dest cpu. We're doing
963 * this because either it can't run here any more (set_cpus_allowed()
964 * away from this CPU, or CPU going down), or because we're
965 * attempting to rebalance this task on exec (sched_exec).
967 * So we race with normal scheduler movements, but that's OK, as long
968 * as the task is no longer on this CPU.
970 static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
972 if (unlikely(!cpu_active(dest_cpu)))
975 /* Affinity changed (again). */
976 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
979 rq = move_queued_task(rq, p, dest_cpu);
985 * migration_cpu_stop - this will be executed by a highprio stopper thread
986 * and performs thread migration by bumping thread off CPU then
987 * 'pushing' onto another runqueue.
989 static int migration_cpu_stop(void *data)
991 struct migration_arg *arg = data;
992 struct task_struct *p = arg->task;
993 struct rq *rq = this_rq();
996 * The original target cpu might have gone down and we might
997 * be on another cpu but it doesn't matter.
1001 * We need to explicitly wake pending tasks before running
1002 * __migrate_task() such that we will not miss enforcing cpus_allowed
1003 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1005 sched_ttwu_pending();
1007 raw_spin_lock(&p->pi_lock);
1008 raw_spin_lock(&rq->lock);
1010 * If task_rq(p) != rq, it cannot be migrated here, because we're
1011 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1012 * we're holding p->pi_lock.
1014 if (task_rq(p) == rq && task_on_rq_queued(p))
1015 rq = __migrate_task(rq, p, arg->dest_cpu);
1016 raw_spin_unlock(&rq->lock);
1017 raw_spin_unlock(&p->pi_lock);
1024 * sched_class::set_cpus_allowed must do the below, but is not required to
1025 * actually call this function.
1027 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1029 cpumask_copy(&p->cpus_allowed, new_mask);
1030 p->nr_cpus_allowed = cpumask_weight(new_mask);
1033 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1035 struct rq *rq = task_rq(p);
1036 bool queued, running;
1038 lockdep_assert_held(&p->pi_lock);
1040 queued = task_on_rq_queued(p);
1041 running = task_current(rq, p);
1045 * Because __kthread_bind() calls this on blocked tasks without
1048 lockdep_assert_held(&rq->lock);
1049 dequeue_task(rq, p, DEQUEUE_SAVE);
1052 put_prev_task(rq, p);
1054 p->sched_class->set_cpus_allowed(p, new_mask);
1057 p->sched_class->set_curr_task(rq);
1059 enqueue_task(rq, p, ENQUEUE_RESTORE);
1063 * Change a given task's CPU affinity. Migrate the thread to a
1064 * proper CPU and schedule it away if the CPU it's executing on
1065 * is removed from the allowed bitmask.
1067 * NOTE: the caller must have a valid reference to the task, the
1068 * task must not exit() & deallocate itself prematurely. The
1069 * call is not atomic; no spinlocks may be held.
1071 static int __set_cpus_allowed_ptr(struct task_struct *p,
1072 const struct cpumask *new_mask, bool check)
1074 unsigned long flags;
1076 unsigned int dest_cpu;
1079 rq = task_rq_lock(p, &flags);
1082 * Must re-check here, to close a race against __kthread_bind(),
1083 * sched_setaffinity() is not guaranteed to observe the flag.
1085 if (check && (p->flags & PF_NO_SETAFFINITY)) {
1090 if (cpumask_equal(&p->cpus_allowed, new_mask))
1093 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
1098 do_set_cpus_allowed(p, new_mask);
1100 /* Can the task run on the task's current CPU? If so, we're done */
1101 if (cpumask_test_cpu(task_cpu(p), new_mask))
1104 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
1105 if (task_running(rq, p) || p->state == TASK_WAKING) {
1106 struct migration_arg arg = { p, dest_cpu };
1107 /* Need help from migration thread: drop lock and wait. */
1108 task_rq_unlock(rq, p, &flags);
1109 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1110 tlb_migrate_finish(p->mm);
1112 } else if (task_on_rq_queued(p)) {
1114 * OK, since we're going to drop the lock immediately
1115 * afterwards anyway.
1117 lockdep_unpin_lock(&rq->lock);
1118 rq = move_queued_task(rq, p, dest_cpu);
1119 lockdep_pin_lock(&rq->lock);
1122 task_rq_unlock(rq, p, &flags);
1127 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1129 return __set_cpus_allowed_ptr(p, new_mask, false);
1131 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1133 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1135 #ifdef CONFIG_SCHED_DEBUG
1137 * We should never call set_task_cpu() on a blocked task,
1138 * ttwu() will sort out the placement.
1140 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1144 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1145 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1146 * time relying on p->on_rq.
1148 WARN_ON_ONCE(p->state == TASK_RUNNING &&
1149 p->sched_class == &fair_sched_class &&
1150 (p->on_rq && !task_on_rq_migrating(p)));
1152 #ifdef CONFIG_LOCKDEP
1154 * The caller should hold either p->pi_lock or rq->lock, when changing
1155 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1157 * sched_move_task() holds both and thus holding either pins the cgroup,
1160 * Furthermore, all task_rq users should acquire both locks, see
1163 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1164 lockdep_is_held(&task_rq(p)->lock)));
1168 trace_sched_migrate_task(p, new_cpu);
1170 if (task_cpu(p) != new_cpu) {
1171 if (p->sched_class->migrate_task_rq)
1172 p->sched_class->migrate_task_rq(p);
1173 p->se.nr_migrations++;
1174 perf_event_task_migrate(p);
1177 __set_task_cpu(p, new_cpu);
1180 static void __migrate_swap_task(struct task_struct *p, int cpu)
1182 if (task_on_rq_queued(p)) {
1183 struct rq *src_rq, *dst_rq;
1185 src_rq = task_rq(p);
1186 dst_rq = cpu_rq(cpu);
1188 p->on_rq = TASK_ON_RQ_MIGRATING;
1189 deactivate_task(src_rq, p, 0);
1190 set_task_cpu(p, cpu);
1191 activate_task(dst_rq, p, 0);
1192 p->on_rq = TASK_ON_RQ_QUEUED;
1193 check_preempt_curr(dst_rq, p, 0);
1196 * Task isn't running anymore; make it appear like we migrated
1197 * it before it went to sleep. This means on wakeup we make the
1198 * previous cpu our targer instead of where it really is.
1204 struct migration_swap_arg {
1205 struct task_struct *src_task, *dst_task;
1206 int src_cpu, dst_cpu;
1209 static int migrate_swap_stop(void *data)
1211 struct migration_swap_arg *arg = data;
1212 struct rq *src_rq, *dst_rq;
1215 if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1218 src_rq = cpu_rq(arg->src_cpu);
1219 dst_rq = cpu_rq(arg->dst_cpu);
1221 double_raw_lock(&arg->src_task->pi_lock,
1222 &arg->dst_task->pi_lock);
1223 double_rq_lock(src_rq, dst_rq);
1225 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1228 if (task_cpu(arg->src_task) != arg->src_cpu)
1231 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1234 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1237 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1238 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1243 double_rq_unlock(src_rq, dst_rq);
1244 raw_spin_unlock(&arg->dst_task->pi_lock);
1245 raw_spin_unlock(&arg->src_task->pi_lock);
1251 * Cross migrate two tasks
1253 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1255 struct migration_swap_arg arg;
1258 arg = (struct migration_swap_arg){
1260 .src_cpu = task_cpu(cur),
1262 .dst_cpu = task_cpu(p),
1265 if (arg.src_cpu == arg.dst_cpu)
1269 * These three tests are all lockless; this is OK since all of them
1270 * will be re-checked with proper locks held further down the line.
1272 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1275 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1278 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1281 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1282 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1289 * wait_task_inactive - wait for a thread to unschedule.
1291 * If @match_state is nonzero, it's the @p->state value just checked and
1292 * not expected to change. If it changes, i.e. @p might have woken up,
1293 * then return zero. When we succeed in waiting for @p to be off its CPU,
1294 * we return a positive number (its total switch count). If a second call
1295 * a short while later returns the same number, the caller can be sure that
1296 * @p has remained unscheduled the whole time.
1298 * The caller must ensure that the task *will* unschedule sometime soon,
1299 * else this function might spin for a *long* time. This function can't
1300 * be called with interrupts off, or it may introduce deadlock with
1301 * smp_call_function() if an IPI is sent by the same process we are
1302 * waiting to become inactive.
1304 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1306 unsigned long flags;
1307 int running, queued;
1313 * We do the initial early heuristics without holding
1314 * any task-queue locks at all. We'll only try to get
1315 * the runqueue lock when things look like they will
1321 * If the task is actively running on another CPU
1322 * still, just relax and busy-wait without holding
1325 * NOTE! Since we don't hold any locks, it's not
1326 * even sure that "rq" stays as the right runqueue!
1327 * But we don't care, since "task_running()" will
1328 * return false if the runqueue has changed and p
1329 * is actually now running somewhere else!
1331 while (task_running(rq, p)) {
1332 if (match_state && unlikely(p->state != match_state))
1338 * Ok, time to look more closely! We need the rq
1339 * lock now, to be *sure*. If we're wrong, we'll
1340 * just go back and repeat.
1342 rq = task_rq_lock(p, &flags);
1343 trace_sched_wait_task(p);
1344 running = task_running(rq, p);
1345 queued = task_on_rq_queued(p);
1347 if (!match_state || p->state == match_state)
1348 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1349 task_rq_unlock(rq, p, &flags);
1352 * If it changed from the expected state, bail out now.
1354 if (unlikely(!ncsw))
1358 * Was it really running after all now that we
1359 * checked with the proper locks actually held?
1361 * Oops. Go back and try again..
1363 if (unlikely(running)) {
1369 * It's not enough that it's not actively running,
1370 * it must be off the runqueue _entirely_, and not
1373 * So if it was still runnable (but just not actively
1374 * running right now), it's preempted, and we should
1375 * yield - it could be a while.
1377 if (unlikely(queued)) {
1378 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1380 set_current_state(TASK_UNINTERRUPTIBLE);
1381 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1386 * Ahh, all good. It wasn't running, and it wasn't
1387 * runnable, which means that it will never become
1388 * running in the future either. We're all done!
1397 * kick_process - kick a running thread to enter/exit the kernel
1398 * @p: the to-be-kicked thread
1400 * Cause a process which is running on another CPU to enter
1401 * kernel-mode, without any delay. (to get signals handled.)
1403 * NOTE: this function doesn't have to take the runqueue lock,
1404 * because all it wants to ensure is that the remote task enters
1405 * the kernel. If the IPI races and the task has been migrated
1406 * to another CPU then no harm is done and the purpose has been
1409 void kick_process(struct task_struct *p)
1415 if ((cpu != smp_processor_id()) && task_curr(p))
1416 smp_send_reschedule(cpu);
1419 EXPORT_SYMBOL_GPL(kick_process);
1422 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1424 static int select_fallback_rq(int cpu, struct task_struct *p)
1426 int nid = cpu_to_node(cpu);
1427 const struct cpumask *nodemask = NULL;
1428 enum { cpuset, possible, fail } state = cpuset;
1432 * If the node that the cpu is on has been offlined, cpu_to_node()
1433 * will return -1. There is no cpu on the node, and we should
1434 * select the cpu on the other node.
1437 nodemask = cpumask_of_node(nid);
1439 /* Look for allowed, online CPU in same node. */
1440 for_each_cpu(dest_cpu, nodemask) {
1441 if (!cpu_online(dest_cpu))
1443 if (!cpu_active(dest_cpu))
1445 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1451 /* Any allowed, online CPU? */
1452 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1453 if (!cpu_online(dest_cpu))
1455 if (!cpu_active(dest_cpu))
1460 /* No more Mr. Nice Guy. */
1463 if (IS_ENABLED(CONFIG_CPUSETS)) {
1464 cpuset_cpus_allowed_fallback(p);
1470 do_set_cpus_allowed(p, cpu_possible_mask);
1481 if (state != cpuset) {
1483 * Don't tell them about moving exiting tasks or
1484 * kernel threads (both mm NULL), since they never
1487 if (p->mm && printk_ratelimit()) {
1488 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1489 task_pid_nr(p), p->comm, cpu);
1497 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1500 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1502 lockdep_assert_held(&p->pi_lock);
1504 if (p->nr_cpus_allowed > 1)
1505 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1508 * In order not to call set_task_cpu() on a blocking task we need
1509 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1512 * Since this is common to all placement strategies, this lives here.
1514 * [ this allows ->select_task() to simply return task_cpu(p) and
1515 * not worry about this generic constraint ]
1517 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1519 cpu = select_fallback_rq(task_cpu(p), p);
1524 static void update_avg(u64 *avg, u64 sample)
1526 s64 diff = sample - *avg;
1532 static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1533 const struct cpumask *new_mask, bool check)
1535 return set_cpus_allowed_ptr(p, new_mask);
1538 #endif /* CONFIG_SMP */
1541 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1543 #ifdef CONFIG_SCHEDSTATS
1544 struct rq *rq = this_rq();
1547 int this_cpu = smp_processor_id();
1549 if (cpu == this_cpu) {
1550 schedstat_inc(rq, ttwu_local);
1551 schedstat_inc(p, se.statistics.nr_wakeups_local);
1553 struct sched_domain *sd;
1555 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1557 for_each_domain(this_cpu, sd) {
1558 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1559 schedstat_inc(sd, ttwu_wake_remote);
1566 if (wake_flags & WF_MIGRATED)
1567 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1569 #endif /* CONFIG_SMP */
1571 schedstat_inc(rq, ttwu_count);
1572 schedstat_inc(p, se.statistics.nr_wakeups);
1574 if (wake_flags & WF_SYNC)
1575 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1577 #endif /* CONFIG_SCHEDSTATS */
1580 static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1582 activate_task(rq, p, en_flags);
1583 p->on_rq = TASK_ON_RQ_QUEUED;
1585 /* if a worker is waking up, notify workqueue */
1586 if (p->flags & PF_WQ_WORKER)
1587 wq_worker_waking_up(p, cpu_of(rq));
1591 * Mark the task runnable and perform wakeup-preemption.
1594 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1596 check_preempt_curr(rq, p, wake_flags);
1597 p->state = TASK_RUNNING;
1598 trace_sched_wakeup(p);
1601 if (p->sched_class->task_woken) {
1603 * Our task @p is fully woken up and running; so its safe to
1604 * drop the rq->lock, hereafter rq is only used for statistics.
1606 lockdep_unpin_lock(&rq->lock);
1607 p->sched_class->task_woken(rq, p);
1608 lockdep_pin_lock(&rq->lock);
1611 if (rq->idle_stamp) {
1612 u64 delta = rq_clock(rq) - rq->idle_stamp;
1613 u64 max = 2*rq->max_idle_balance_cost;
1615 update_avg(&rq->avg_idle, delta);
1617 if (rq->avg_idle > max)
1626 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1628 lockdep_assert_held(&rq->lock);
1631 if (p->sched_contributes_to_load)
1632 rq->nr_uninterruptible--;
1635 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1636 ttwu_do_wakeup(rq, p, wake_flags);
1640 * Called in case the task @p isn't fully descheduled from its runqueue,
1641 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1642 * since all we need to do is flip p->state to TASK_RUNNING, since
1643 * the task is still ->on_rq.
1645 static int ttwu_remote(struct task_struct *p, int wake_flags)
1650 rq = __task_rq_lock(p);
1651 if (task_on_rq_queued(p)) {
1652 /* check_preempt_curr() may use rq clock */
1653 update_rq_clock(rq);
1654 ttwu_do_wakeup(rq, p, wake_flags);
1657 __task_rq_unlock(rq);
1663 void sched_ttwu_pending(void)
1665 struct rq *rq = this_rq();
1666 struct llist_node *llist = llist_del_all(&rq->wake_list);
1667 struct task_struct *p;
1668 unsigned long flags;
1673 raw_spin_lock_irqsave(&rq->lock, flags);
1674 lockdep_pin_lock(&rq->lock);
1677 p = llist_entry(llist, struct task_struct, wake_entry);
1678 llist = llist_next(llist);
1679 ttwu_do_activate(rq, p, 0);
1682 lockdep_unpin_lock(&rq->lock);
1683 raw_spin_unlock_irqrestore(&rq->lock, flags);
1686 void scheduler_ipi(void)
1689 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1690 * TIF_NEED_RESCHED remotely (for the first time) will also send
1693 preempt_fold_need_resched();
1695 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1699 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1700 * traditionally all their work was done from the interrupt return
1701 * path. Now that we actually do some work, we need to make sure
1704 * Some archs already do call them, luckily irq_enter/exit nest
1707 * Arguably we should visit all archs and update all handlers,
1708 * however a fair share of IPIs are still resched only so this would
1709 * somewhat pessimize the simple resched case.
1712 sched_ttwu_pending();
1715 * Check if someone kicked us for doing the nohz idle load balance.
1717 if (unlikely(got_nohz_idle_kick())) {
1718 this_rq()->idle_balance = 1;
1719 raise_softirq_irqoff(SCHED_SOFTIRQ);
1724 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1726 struct rq *rq = cpu_rq(cpu);
1728 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1729 if (!set_nr_if_polling(rq->idle))
1730 smp_send_reschedule(cpu);
1732 trace_sched_wake_idle_without_ipi(cpu);
1736 void wake_up_if_idle(int cpu)
1738 struct rq *rq = cpu_rq(cpu);
1739 unsigned long flags;
1743 if (!is_idle_task(rcu_dereference(rq->curr)))
1746 if (set_nr_if_polling(rq->idle)) {
1747 trace_sched_wake_idle_without_ipi(cpu);
1749 raw_spin_lock_irqsave(&rq->lock, flags);
1750 if (is_idle_task(rq->curr))
1751 smp_send_reschedule(cpu);
1752 /* Else cpu is not in idle, do nothing here */
1753 raw_spin_unlock_irqrestore(&rq->lock, flags);
1760 bool cpus_share_cache(int this_cpu, int that_cpu)
1762 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1764 #endif /* CONFIG_SMP */
1766 static void ttwu_queue(struct task_struct *p, int cpu)
1768 struct rq *rq = cpu_rq(cpu);
1770 #if defined(CONFIG_SMP)
1771 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1772 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1773 ttwu_queue_remote(p, cpu);
1778 raw_spin_lock(&rq->lock);
1779 lockdep_pin_lock(&rq->lock);
1780 ttwu_do_activate(rq, p, 0);
1781 lockdep_unpin_lock(&rq->lock);
1782 raw_spin_unlock(&rq->lock);
1786 * Notes on Program-Order guarantees on SMP systems.
1790 * The basic program-order guarantee on SMP systems is that when a task [t]
1791 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1792 * execution on its new cpu [c1].
1794 * For migration (of runnable tasks) this is provided by the following means:
1796 * A) UNLOCK of the rq(c0)->lock scheduling out task t
1797 * B) migration for t is required to synchronize *both* rq(c0)->lock and
1798 * rq(c1)->lock (if not at the same time, then in that order).
1799 * C) LOCK of the rq(c1)->lock scheduling in task
1801 * Transitivity guarantees that B happens after A and C after B.
1802 * Note: we only require RCpc transitivity.
1803 * Note: the cpu doing B need not be c0 or c1
1812 * UNLOCK rq(0)->lock
1814 * LOCK rq(0)->lock // orders against CPU0
1816 * UNLOCK rq(0)->lock
1820 * UNLOCK rq(1)->lock
1822 * LOCK rq(1)->lock // orders against CPU2
1825 * UNLOCK rq(1)->lock
1828 * BLOCKING -- aka. SLEEP + WAKEUP
1830 * For blocking we (obviously) need to provide the same guarantee as for
1831 * migration. However the means are completely different as there is no lock
1832 * chain to provide order. Instead we do:
1834 * 1) smp_store_release(X->on_cpu, 0)
1835 * 2) smp_cond_acquire(!X->on_cpu)
1839 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
1841 * LOCK rq(0)->lock LOCK X->pi_lock
1844 * smp_store_release(X->on_cpu, 0);
1846 * smp_cond_acquire(!X->on_cpu);
1852 * X->state = RUNNING
1853 * UNLOCK rq(2)->lock
1855 * LOCK rq(2)->lock // orders against CPU1
1858 * UNLOCK rq(2)->lock
1861 * UNLOCK rq(0)->lock
1864 * However; for wakeups there is a second guarantee we must provide, namely we
1865 * must observe the state that lead to our wakeup. That is, not only must our
1866 * task observe its own prior state, it must also observe the stores prior to
1869 * This means that any means of doing remote wakeups must order the CPU doing
1870 * the wakeup against the CPU the task is going to end up running on. This,
1871 * however, is already required for the regular Program-Order guarantee above,
1872 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire).
1877 * try_to_wake_up - wake up a thread
1878 * @p: the thread to be awakened
1879 * @state: the mask of task states that can be woken
1880 * @wake_flags: wake modifier flags (WF_*)
1882 * Put it on the run-queue if it's not already there. The "current"
1883 * thread is always on the run-queue (except when the actual
1884 * re-schedule is in progress), and as such you're allowed to do
1885 * the simpler "current->state = TASK_RUNNING" to mark yourself
1886 * runnable without the overhead of this.
1888 * Return: %true if @p was woken up, %false if it was already running.
1889 * or @state didn't match @p's state.
1892 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1894 unsigned long flags;
1895 int cpu, success = 0;
1898 * If we are going to wake up a thread waiting for CONDITION we
1899 * need to ensure that CONDITION=1 done by the caller can not be
1900 * reordered with p->state check below. This pairs with mb() in
1901 * set_current_state() the waiting thread does.
1903 smp_mb__before_spinlock();
1904 raw_spin_lock_irqsave(&p->pi_lock, flags);
1905 if (!(p->state & state))
1908 trace_sched_waking(p);
1910 success = 1; /* we're going to change ->state */
1913 if (p->on_rq && ttwu_remote(p, wake_flags))
1918 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
1919 * possible to, falsely, observe p->on_cpu == 0.
1921 * One must be running (->on_cpu == 1) in order to remove oneself
1922 * from the runqueue.
1924 * [S] ->on_cpu = 1; [L] ->on_rq
1928 * [S] ->on_rq = 0; [L] ->on_cpu
1930 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
1931 * from the consecutive calls to schedule(); the first switching to our
1932 * task, the second putting it to sleep.
1937 * If the owning (remote) cpu is still in the middle of schedule() with
1938 * this task as prev, wait until its done referencing the task.
1940 * Pairs with the smp_store_release() in finish_lock_switch().
1942 * This ensures that tasks getting woken will be fully ordered against
1943 * their previous state and preserve Program Order.
1945 smp_cond_acquire(!p->on_cpu);
1947 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1948 p->state = TASK_WAKING;
1950 if (p->sched_class->task_waking)
1951 p->sched_class->task_waking(p);
1953 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1954 if (task_cpu(p) != cpu) {
1955 wake_flags |= WF_MIGRATED;
1956 set_task_cpu(p, cpu);
1958 #endif /* CONFIG_SMP */
1962 if (schedstat_enabled())
1963 ttwu_stat(p, cpu, wake_flags);
1965 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1971 * try_to_wake_up_local - try to wake up a local task with rq lock held
1972 * @p: the thread to be awakened
1974 * Put @p on the run-queue if it's not already there. The caller must
1975 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1978 static void try_to_wake_up_local(struct task_struct *p)
1980 struct rq *rq = task_rq(p);
1982 if (WARN_ON_ONCE(rq != this_rq()) ||
1983 WARN_ON_ONCE(p == current))
1986 lockdep_assert_held(&rq->lock);
1988 if (!raw_spin_trylock(&p->pi_lock)) {
1990 * This is OK, because current is on_cpu, which avoids it being
1991 * picked for load-balance and preemption/IRQs are still
1992 * disabled avoiding further scheduler activity on it and we've
1993 * not yet picked a replacement task.
1995 lockdep_unpin_lock(&rq->lock);
1996 raw_spin_unlock(&rq->lock);
1997 raw_spin_lock(&p->pi_lock);
1998 raw_spin_lock(&rq->lock);
1999 lockdep_pin_lock(&rq->lock);
2002 if (!(p->state & TASK_NORMAL))
2005 trace_sched_waking(p);
2007 if (!task_on_rq_queued(p))
2008 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2010 ttwu_do_wakeup(rq, p, 0);
2011 if (schedstat_enabled())
2012 ttwu_stat(p, smp_processor_id(), 0);
2014 raw_spin_unlock(&p->pi_lock);
2018 * wake_up_process - Wake up a specific process
2019 * @p: The process to be woken up.
2021 * Attempt to wake up the nominated process and move it to the set of runnable
2024 * Return: 1 if the process was woken up, 0 if it was already running.
2026 * It may be assumed that this function implies a write memory barrier before
2027 * changing the task state if and only if any tasks are woken up.
2029 int wake_up_process(struct task_struct *p)
2031 return try_to_wake_up(p, TASK_NORMAL, 0);
2033 EXPORT_SYMBOL(wake_up_process);
2035 int wake_up_state(struct task_struct *p, unsigned int state)
2037 return try_to_wake_up(p, state, 0);
2041 * This function clears the sched_dl_entity static params.
2043 void __dl_clear_params(struct task_struct *p)
2045 struct sched_dl_entity *dl_se = &p->dl;
2047 dl_se->dl_runtime = 0;
2048 dl_se->dl_deadline = 0;
2049 dl_se->dl_period = 0;
2053 dl_se->dl_throttled = 0;
2055 dl_se->dl_yielded = 0;
2059 * Perform scheduler related setup for a newly forked process p.
2060 * p is forked by current.
2062 * __sched_fork() is basic setup used by init_idle() too:
2064 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
2069 p->se.exec_start = 0;
2070 p->se.sum_exec_runtime = 0;
2071 p->se.prev_sum_exec_runtime = 0;
2072 p->se.nr_migrations = 0;
2074 INIT_LIST_HEAD(&p->se.group_node);
2076 #ifdef CONFIG_FAIR_GROUP_SCHED
2077 p->se.cfs_rq = NULL;
2080 #ifdef CONFIG_SCHEDSTATS
2081 /* Even if schedstat is disabled, there should not be garbage */
2082 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2085 RB_CLEAR_NODE(&p->dl.rb_node);
2086 init_dl_task_timer(&p->dl);
2087 __dl_clear_params(p);
2089 INIT_LIST_HEAD(&p->rt.run_list);
2091 p->rt.time_slice = sched_rr_timeslice;
2095 #ifdef CONFIG_PREEMPT_NOTIFIERS
2096 INIT_HLIST_HEAD(&p->preempt_notifiers);
2099 #ifdef CONFIG_NUMA_BALANCING
2100 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2101 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2102 p->mm->numa_scan_seq = 0;
2105 if (clone_flags & CLONE_VM)
2106 p->numa_preferred_nid = current->numa_preferred_nid;
2108 p->numa_preferred_nid = -1;
2110 p->node_stamp = 0ULL;
2111 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2112 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2113 p->numa_work.next = &p->numa_work;
2114 p->numa_faults = NULL;
2115 p->last_task_numa_placement = 0;
2116 p->last_sum_exec_runtime = 0;
2118 p->numa_group = NULL;
2119 #endif /* CONFIG_NUMA_BALANCING */
2122 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
2124 #ifdef CONFIG_NUMA_BALANCING
2126 void set_numabalancing_state(bool enabled)
2129 static_branch_enable(&sched_numa_balancing);
2131 static_branch_disable(&sched_numa_balancing);
2134 #ifdef CONFIG_PROC_SYSCTL
2135 int sysctl_numa_balancing(struct ctl_table *table, int write,
2136 void __user *buffer, size_t *lenp, loff_t *ppos)
2140 int state = static_branch_likely(&sched_numa_balancing);
2142 if (write && !capable(CAP_SYS_ADMIN))
2147 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2151 set_numabalancing_state(state);
2157 DEFINE_STATIC_KEY_FALSE(sched_schedstats);
2159 #ifdef CONFIG_SCHEDSTATS
2160 static void set_schedstats(bool enabled)
2163 static_branch_enable(&sched_schedstats);
2165 static_branch_disable(&sched_schedstats);
2168 void force_schedstat_enabled(void)
2170 if (!schedstat_enabled()) {
2171 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
2172 static_branch_enable(&sched_schedstats);
2176 static int __init setup_schedstats(char *str)
2182 if (!strcmp(str, "enable")) {
2183 set_schedstats(true);
2185 } else if (!strcmp(str, "disable")) {
2186 set_schedstats(false);
2191 pr_warn("Unable to parse schedstats=\n");
2195 __setup("schedstats=", setup_schedstats);
2197 #ifdef CONFIG_PROC_SYSCTL
2198 int sysctl_schedstats(struct ctl_table *table, int write,
2199 void __user *buffer, size_t *lenp, loff_t *ppos)
2203 int state = static_branch_likely(&sched_schedstats);
2205 if (write && !capable(CAP_SYS_ADMIN))
2210 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2214 set_schedstats(state);
2221 * fork()/clone()-time setup:
2223 int sched_fork(unsigned long clone_flags, struct task_struct *p)
2225 unsigned long flags;
2226 int cpu = get_cpu();
2228 __sched_fork(clone_flags, p);
2230 * We mark the process as running here. This guarantees that
2231 * nobody will actually run it, and a signal or other external
2232 * event cannot wake it up and insert it on the runqueue either.
2234 p->state = TASK_RUNNING;
2237 * Make sure we do not leak PI boosting priority to the child.
2239 p->prio = current->normal_prio;
2242 * Revert to default priority/policy on fork if requested.
2244 if (unlikely(p->sched_reset_on_fork)) {
2245 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2246 p->policy = SCHED_NORMAL;
2247 p->static_prio = NICE_TO_PRIO(0);
2249 } else if (PRIO_TO_NICE(p->static_prio) < 0)
2250 p->static_prio = NICE_TO_PRIO(0);
2252 p->prio = p->normal_prio = __normal_prio(p);
2256 * We don't need the reset flag anymore after the fork. It has
2257 * fulfilled its duty:
2259 p->sched_reset_on_fork = 0;
2262 if (dl_prio(p->prio)) {
2265 } else if (rt_prio(p->prio)) {
2266 p->sched_class = &rt_sched_class;
2268 p->sched_class = &fair_sched_class;
2271 if (p->sched_class->task_fork)
2272 p->sched_class->task_fork(p);
2275 * The child is not yet in the pid-hash so no cgroup attach races,
2276 * and the cgroup is pinned to this child due to cgroup_fork()
2277 * is ran before sched_fork().
2279 * Silence PROVE_RCU.
2281 raw_spin_lock_irqsave(&p->pi_lock, flags);
2282 set_task_cpu(p, cpu);
2283 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2285 #ifdef CONFIG_SCHED_INFO
2286 if (likely(sched_info_on()))
2287 memset(&p->sched_info, 0, sizeof(p->sched_info));
2289 #if defined(CONFIG_SMP)
2292 init_task_preempt_count(p);
2294 plist_node_init(&p->pushable_tasks, MAX_PRIO);
2295 RB_CLEAR_NODE(&p->pushable_dl_tasks);
2302 unsigned long to_ratio(u64 period, u64 runtime)
2304 if (runtime == RUNTIME_INF)
2308 * Doing this here saves a lot of checks in all
2309 * the calling paths, and returning zero seems
2310 * safe for them anyway.
2315 return div64_u64(runtime << 20, period);
2319 inline struct dl_bw *dl_bw_of(int i)
2321 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2322 "sched RCU must be held");
2323 return &cpu_rq(i)->rd->dl_bw;
2326 static inline int dl_bw_cpus(int i)
2328 struct root_domain *rd = cpu_rq(i)->rd;
2331 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2332 "sched RCU must be held");
2333 for_each_cpu_and(i, rd->span, cpu_active_mask)
2339 inline struct dl_bw *dl_bw_of(int i)
2341 return &cpu_rq(i)->dl.dl_bw;
2344 static inline int dl_bw_cpus(int i)
2351 * We must be sure that accepting a new task (or allowing changing the
2352 * parameters of an existing one) is consistent with the bandwidth
2353 * constraints. If yes, this function also accordingly updates the currently
2354 * allocated bandwidth to reflect the new situation.
2356 * This function is called while holding p's rq->lock.
2358 * XXX we should delay bw change until the task's 0-lag point, see
2361 static int dl_overflow(struct task_struct *p, int policy,
2362 const struct sched_attr *attr)
2365 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2366 u64 period = attr->sched_period ?: attr->sched_deadline;
2367 u64 runtime = attr->sched_runtime;
2368 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2371 if (new_bw == p->dl.dl_bw)
2375 * Either if a task, enters, leave, or stays -deadline but changes
2376 * its parameters, we may need to update accordingly the total
2377 * allocated bandwidth of the container.
2379 raw_spin_lock(&dl_b->lock);
2380 cpus = dl_bw_cpus(task_cpu(p));
2381 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2382 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2383 __dl_add(dl_b, new_bw);
2385 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2386 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2387 __dl_clear(dl_b, p->dl.dl_bw);
2388 __dl_add(dl_b, new_bw);
2390 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2391 __dl_clear(dl_b, p->dl.dl_bw);
2394 raw_spin_unlock(&dl_b->lock);
2399 extern void init_dl_bw(struct dl_bw *dl_b);
2402 * wake_up_new_task - wake up a newly created task for the first time.
2404 * This function will do some initial scheduler statistics housekeeping
2405 * that must be done for every newly created context, then puts the task
2406 * on the runqueue and wakes it.
2408 void wake_up_new_task(struct task_struct *p)
2410 unsigned long flags;
2413 raw_spin_lock_irqsave(&p->pi_lock, flags);
2414 /* Initialize new task's runnable average */
2415 init_entity_runnable_average(&p->se);
2418 * Fork balancing, do it here and not earlier because:
2419 * - cpus_allowed can change in the fork path
2420 * - any previously selected cpu might disappear through hotplug
2422 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2425 rq = __task_rq_lock(p);
2426 activate_task(rq, p, 0);
2427 p->on_rq = TASK_ON_RQ_QUEUED;
2428 trace_sched_wakeup_new(p);
2429 check_preempt_curr(rq, p, WF_FORK);
2431 if (p->sched_class->task_woken) {
2433 * Nothing relies on rq->lock after this, so its fine to
2436 lockdep_unpin_lock(&rq->lock);
2437 p->sched_class->task_woken(rq, p);
2438 lockdep_pin_lock(&rq->lock);
2441 task_rq_unlock(rq, p, &flags);
2444 #ifdef CONFIG_PREEMPT_NOTIFIERS
2446 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
2448 void preempt_notifier_inc(void)
2450 static_key_slow_inc(&preempt_notifier_key);
2452 EXPORT_SYMBOL_GPL(preempt_notifier_inc);
2454 void preempt_notifier_dec(void)
2456 static_key_slow_dec(&preempt_notifier_key);
2458 EXPORT_SYMBOL_GPL(preempt_notifier_dec);
2461 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2462 * @notifier: notifier struct to register
2464 void preempt_notifier_register(struct preempt_notifier *notifier)
2466 if (!static_key_false(&preempt_notifier_key))
2467 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2469 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2471 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2474 * preempt_notifier_unregister - no longer interested in preemption notifications
2475 * @notifier: notifier struct to unregister
2477 * This is *not* safe to call from within a preemption notifier.
2479 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2481 hlist_del(¬ifier->link);
2483 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2485 static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2487 struct preempt_notifier *notifier;
2489 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2490 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2493 static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2495 if (static_key_false(&preempt_notifier_key))
2496 __fire_sched_in_preempt_notifiers(curr);
2500 __fire_sched_out_preempt_notifiers(struct task_struct *curr,
2501 struct task_struct *next)
2503 struct preempt_notifier *notifier;
2505 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2506 notifier->ops->sched_out(notifier, next);
2509 static __always_inline void
2510 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2511 struct task_struct *next)
2513 if (static_key_false(&preempt_notifier_key))
2514 __fire_sched_out_preempt_notifiers(curr, next);
2517 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2519 static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2524 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2525 struct task_struct *next)
2529 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2532 * prepare_task_switch - prepare to switch tasks
2533 * @rq: the runqueue preparing to switch
2534 * @prev: the current task that is being switched out
2535 * @next: the task we are going to switch to.
2537 * This is called with the rq lock held and interrupts off. It must
2538 * be paired with a subsequent finish_task_switch after the context
2541 * prepare_task_switch sets up locking and calls architecture specific
2545 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2546 struct task_struct *next)
2548 sched_info_switch(rq, prev, next);
2549 perf_event_task_sched_out(prev, next);
2550 fire_sched_out_preempt_notifiers(prev, next);
2551 prepare_lock_switch(rq, next);
2552 prepare_arch_switch(next);
2556 * finish_task_switch - clean up after a task-switch
2557 * @prev: the thread we just switched away from.
2559 * finish_task_switch must be called after the context switch, paired
2560 * with a prepare_task_switch call before the context switch.
2561 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2562 * and do any other architecture-specific cleanup actions.
2564 * Note that we may have delayed dropping an mm in context_switch(). If
2565 * so, we finish that here outside of the runqueue lock. (Doing it
2566 * with the lock held can cause deadlocks; see schedule() for
2569 * The context switch have flipped the stack from under us and restored the
2570 * local variables which were saved when this task called schedule() in the
2571 * past. prev == current is still correct but we need to recalculate this_rq
2572 * because prev may have moved to another CPU.
2574 static struct rq *finish_task_switch(struct task_struct *prev)
2575 __releases(rq->lock)
2577 struct rq *rq = this_rq();
2578 struct mm_struct *mm = rq->prev_mm;
2582 * The previous task will have left us with a preempt_count of 2
2583 * because it left us after:
2586 * preempt_disable(); // 1
2588 * raw_spin_lock_irq(&rq->lock) // 2
2590 * Also, see FORK_PREEMPT_COUNT.
2592 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
2593 "corrupted preempt_count: %s/%d/0x%x\n",
2594 current->comm, current->pid, preempt_count()))
2595 preempt_count_set(FORK_PREEMPT_COUNT);
2600 * A task struct has one reference for the use as "current".
2601 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2602 * schedule one last time. The schedule call will never return, and
2603 * the scheduled task must drop that reference.
2605 * We must observe prev->state before clearing prev->on_cpu (in
2606 * finish_lock_switch), otherwise a concurrent wakeup can get prev
2607 * running on another CPU and we could rave with its RUNNING -> DEAD
2608 * transition, resulting in a double drop.
2610 prev_state = prev->state;
2611 vtime_task_switch(prev);
2612 perf_event_task_sched_in(prev, current);
2613 finish_lock_switch(rq, prev);
2614 finish_arch_post_lock_switch();
2616 fire_sched_in_preempt_notifiers(current);
2619 if (unlikely(prev_state == TASK_DEAD)) {
2620 if (prev->sched_class->task_dead)
2621 prev->sched_class->task_dead(prev);
2624 * Remove function-return probe instances associated with this
2625 * task and put them back on the free list.
2627 kprobe_flush_task(prev);
2628 put_task_struct(prev);
2631 tick_nohz_task_switch();
2637 /* rq->lock is NOT held, but preemption is disabled */
2638 static void __balance_callback(struct rq *rq)
2640 struct callback_head *head, *next;
2641 void (*func)(struct rq *rq);
2642 unsigned long flags;
2644 raw_spin_lock_irqsave(&rq->lock, flags);
2645 head = rq->balance_callback;
2646 rq->balance_callback = NULL;
2648 func = (void (*)(struct rq *))head->func;
2655 raw_spin_unlock_irqrestore(&rq->lock, flags);
2658 static inline void balance_callback(struct rq *rq)
2660 if (unlikely(rq->balance_callback))
2661 __balance_callback(rq);
2666 static inline void balance_callback(struct rq *rq)
2673 * schedule_tail - first thing a freshly forked thread must call.
2674 * @prev: the thread we just switched away from.
2676 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2677 __releases(rq->lock)
2682 * New tasks start with FORK_PREEMPT_COUNT, see there and
2683 * finish_task_switch() for details.
2685 * finish_task_switch() will drop rq->lock() and lower preempt_count
2686 * and the preempt_enable() will end up enabling preemption (on
2687 * PREEMPT_COUNT kernels).
2690 rq = finish_task_switch(prev);
2691 balance_callback(rq);
2694 if (current->set_child_tid)
2695 put_user(task_pid_vnr(current), current->set_child_tid);
2699 * context_switch - switch to the new MM and the new thread's register state.
2701 static inline struct rq *
2702 context_switch(struct rq *rq, struct task_struct *prev,
2703 struct task_struct *next)
2705 struct mm_struct *mm, *oldmm;
2707 prepare_task_switch(rq, prev, next);
2710 oldmm = prev->active_mm;
2712 * For paravirt, this is coupled with an exit in switch_to to
2713 * combine the page table reload and the switch backend into
2716 arch_start_context_switch(prev);
2719 next->active_mm = oldmm;
2720 atomic_inc(&oldmm->mm_count);
2721 enter_lazy_tlb(oldmm, next);
2723 switch_mm(oldmm, mm, next);
2726 prev->active_mm = NULL;
2727 rq->prev_mm = oldmm;
2730 * Since the runqueue lock will be released by the next
2731 * task (which is an invalid locking op but in the case
2732 * of the scheduler it's an obvious special-case), so we
2733 * do an early lockdep release here:
2735 lockdep_unpin_lock(&rq->lock);
2736 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2738 /* Here we just switch the register state and the stack. */
2739 switch_to(prev, next, prev);
2742 return finish_task_switch(prev);
2746 * nr_running and nr_context_switches:
2748 * externally visible scheduler statistics: current number of runnable
2749 * threads, total number of context switches performed since bootup.
2751 unsigned long nr_running(void)
2753 unsigned long i, sum = 0;
2755 for_each_online_cpu(i)
2756 sum += cpu_rq(i)->nr_running;
2762 * Check if only the current task is running on the cpu.
2764 * Caution: this function does not check that the caller has disabled
2765 * preemption, thus the result might have a time-of-check-to-time-of-use
2766 * race. The caller is responsible to use it correctly, for example:
2768 * - from a non-preemptable section (of course)
2770 * - from a thread that is bound to a single CPU
2772 * - in a loop with very short iterations (e.g. a polling loop)
2774 bool single_task_running(void)
2776 return raw_rq()->nr_running == 1;
2778 EXPORT_SYMBOL(single_task_running);
2780 unsigned long long nr_context_switches(void)
2783 unsigned long long sum = 0;
2785 for_each_possible_cpu(i)
2786 sum += cpu_rq(i)->nr_switches;
2791 unsigned long nr_iowait(void)
2793 unsigned long i, sum = 0;
2795 for_each_possible_cpu(i)
2796 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2801 unsigned long nr_iowait_cpu(int cpu)
2803 struct rq *this = cpu_rq(cpu);
2804 return atomic_read(&this->nr_iowait);
2807 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2809 struct rq *rq = this_rq();
2810 *nr_waiters = atomic_read(&rq->nr_iowait);
2811 *load = rq->load.weight;
2817 * sched_exec - execve() is a valuable balancing opportunity, because at
2818 * this point the task has the smallest effective memory and cache footprint.
2820 void sched_exec(void)
2822 struct task_struct *p = current;
2823 unsigned long flags;
2826 raw_spin_lock_irqsave(&p->pi_lock, flags);
2827 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2828 if (dest_cpu == smp_processor_id())
2831 if (likely(cpu_active(dest_cpu))) {
2832 struct migration_arg arg = { p, dest_cpu };
2834 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2835 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2839 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2844 DEFINE_PER_CPU(struct kernel_stat, kstat);
2845 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2847 EXPORT_PER_CPU_SYMBOL(kstat);
2848 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2851 * Return accounted runtime for the task.
2852 * In case the task is currently running, return the runtime plus current's
2853 * pending runtime that have not been accounted yet.
2855 unsigned long long task_sched_runtime(struct task_struct *p)
2857 unsigned long flags;
2861 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2863 * 64-bit doesn't need locks to atomically read a 64bit value.
2864 * So we have a optimization chance when the task's delta_exec is 0.
2865 * Reading ->on_cpu is racy, but this is ok.
2867 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2868 * If we race with it entering cpu, unaccounted time is 0. This is
2869 * indistinguishable from the read occurring a few cycles earlier.
2870 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2871 * been accounted, so we're correct here as well.
2873 if (!p->on_cpu || !task_on_rq_queued(p))
2874 return p->se.sum_exec_runtime;
2877 rq = task_rq_lock(p, &flags);
2879 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2880 * project cycles that may never be accounted to this
2881 * thread, breaking clock_gettime().
2883 if (task_current(rq, p) && task_on_rq_queued(p)) {
2884 update_rq_clock(rq);
2885 p->sched_class->update_curr(rq);
2887 ns = p->se.sum_exec_runtime;
2888 task_rq_unlock(rq, p, &flags);
2894 * This function gets called by the timer code, with HZ frequency.
2895 * We call it with interrupts disabled.
2897 void scheduler_tick(void)
2899 int cpu = smp_processor_id();
2900 struct rq *rq = cpu_rq(cpu);
2901 struct task_struct *curr = rq->curr;
2905 raw_spin_lock(&rq->lock);
2906 update_rq_clock(rq);
2907 curr->sched_class->task_tick(rq, curr, 0);
2908 update_cpu_load_active(rq);
2909 calc_global_load_tick(rq);
2910 raw_spin_unlock(&rq->lock);
2912 perf_event_task_tick();
2915 rq->idle_balance = idle_cpu(cpu);
2916 trigger_load_balance(rq);
2918 rq_last_tick_reset(rq);
2921 #ifdef CONFIG_NO_HZ_FULL
2923 * scheduler_tick_max_deferment
2925 * Keep at least one tick per second when a single
2926 * active task is running because the scheduler doesn't
2927 * yet completely support full dynticks environment.
2929 * This makes sure that uptime, CFS vruntime, load
2930 * balancing, etc... continue to move forward, even
2931 * with a very low granularity.
2933 * Return: Maximum deferment in nanoseconds.
2935 u64 scheduler_tick_max_deferment(void)
2937 struct rq *rq = this_rq();
2938 unsigned long next, now = READ_ONCE(jiffies);
2940 next = rq->last_sched_tick + HZ;
2942 if (time_before_eq(next, now))
2945 return jiffies_to_nsecs(next - now);
2949 notrace unsigned long get_parent_ip(unsigned long addr)
2951 if (in_lock_functions(addr)) {
2952 addr = CALLER_ADDR2;
2953 if (in_lock_functions(addr))
2954 addr = CALLER_ADDR3;
2959 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2960 defined(CONFIG_PREEMPT_TRACER))
2962 void preempt_count_add(int val)
2964 #ifdef CONFIG_DEBUG_PREEMPT
2968 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2971 __preempt_count_add(val);
2972 #ifdef CONFIG_DEBUG_PREEMPT
2974 * Spinlock count overflowing soon?
2976 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2979 if (preempt_count() == val) {
2980 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2981 #ifdef CONFIG_DEBUG_PREEMPT
2982 current->preempt_disable_ip = ip;
2984 trace_preempt_off(CALLER_ADDR0, ip);
2987 EXPORT_SYMBOL(preempt_count_add);
2988 NOKPROBE_SYMBOL(preempt_count_add);
2990 void preempt_count_sub(int val)
2992 #ifdef CONFIG_DEBUG_PREEMPT
2996 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2999 * Is the spinlock portion underflowing?
3001 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3002 !(preempt_count() & PREEMPT_MASK)))
3006 if (preempt_count() == val)
3007 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
3008 __preempt_count_sub(val);
3010 EXPORT_SYMBOL(preempt_count_sub);
3011 NOKPROBE_SYMBOL(preempt_count_sub);
3016 * Print scheduling while atomic bug:
3018 static noinline void __schedule_bug(struct task_struct *prev)
3020 if (oops_in_progress)
3023 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3024 prev->comm, prev->pid, preempt_count());
3026 debug_show_held_locks(prev);
3028 if (irqs_disabled())
3029 print_irqtrace_events(prev);
3030 #ifdef CONFIG_DEBUG_PREEMPT
3031 if (in_atomic_preempt_off()) {
3032 pr_err("Preemption disabled at:");
3033 print_ip_sym(current->preempt_disable_ip);
3038 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
3042 * Various schedule()-time debugging checks and statistics:
3044 static inline void schedule_debug(struct task_struct *prev)
3046 #ifdef CONFIG_SCHED_STACK_END_CHECK
3047 BUG_ON(task_stack_end_corrupted(prev));
3050 if (unlikely(in_atomic_preempt_off())) {
3051 __schedule_bug(prev);
3052 preempt_count_set(PREEMPT_DISABLED);
3056 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3058 schedstat_inc(this_rq(), sched_count);
3062 * Pick up the highest-prio task:
3064 static inline struct task_struct *
3065 pick_next_task(struct rq *rq, struct task_struct *prev)
3067 const struct sched_class *class = &fair_sched_class;
3068 struct task_struct *p;
3071 * Optimization: we know that if all tasks are in
3072 * the fair class we can call that function directly:
3074 if (likely(prev->sched_class == class &&
3075 rq->nr_running == rq->cfs.h_nr_running)) {
3076 p = fair_sched_class.pick_next_task(rq, prev);
3077 if (unlikely(p == RETRY_TASK))
3080 /* assumes fair_sched_class->next == idle_sched_class */
3082 p = idle_sched_class.pick_next_task(rq, prev);
3088 for_each_class(class) {
3089 p = class->pick_next_task(rq, prev);
3091 if (unlikely(p == RETRY_TASK))
3097 BUG(); /* the idle class will always have a runnable task */
3101 * __schedule() is the main scheduler function.
3103 * The main means of driving the scheduler and thus entering this function are:
3105 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3107 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3108 * paths. For example, see arch/x86/entry_64.S.
3110 * To drive preemption between tasks, the scheduler sets the flag in timer
3111 * interrupt handler scheduler_tick().
3113 * 3. Wakeups don't really cause entry into schedule(). They add a
3114 * task to the run-queue and that's it.
3116 * Now, if the new task added to the run-queue preempts the current
3117 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3118 * called on the nearest possible occasion:
3120 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3122 * - in syscall or exception context, at the next outmost
3123 * preempt_enable(). (this might be as soon as the wake_up()'s
3126 * - in IRQ context, return from interrupt-handler to
3127 * preemptible context
3129 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3132 * - cond_resched() call
3133 * - explicit schedule() call
3134 * - return from syscall or exception to user-space
3135 * - return from interrupt-handler to user-space
3137 * WARNING: must be called with preemption disabled!
3139 static void __sched notrace __schedule(bool preempt)
3141 struct task_struct *prev, *next;
3142 unsigned long *switch_count;
3146 cpu = smp_processor_id();
3151 * do_exit() calls schedule() with preemption disabled as an exception;
3152 * however we must fix that up, otherwise the next task will see an
3153 * inconsistent (higher) preempt count.
3155 * It also avoids the below schedule_debug() test from complaining
3158 if (unlikely(prev->state == TASK_DEAD))
3159 preempt_enable_no_resched_notrace();
3161 schedule_debug(prev);
3163 if (sched_feat(HRTICK))
3166 local_irq_disable();
3167 rcu_note_context_switch();
3170 * Make sure that signal_pending_state()->signal_pending() below
3171 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3172 * done by the caller to avoid the race with signal_wake_up().
3174 smp_mb__before_spinlock();
3175 raw_spin_lock(&rq->lock);
3176 lockdep_pin_lock(&rq->lock);
3178 rq->clock_skip_update <<= 1; /* promote REQ to ACT */
3180 switch_count = &prev->nivcsw;
3181 if (!preempt && prev->state) {
3182 if (unlikely(signal_pending_state(prev->state, prev))) {
3183 prev->state = TASK_RUNNING;
3185 deactivate_task(rq, prev, DEQUEUE_SLEEP);
3189 * If a worker went to sleep, notify and ask workqueue
3190 * whether it wants to wake up a task to maintain
3193 if (prev->flags & PF_WQ_WORKER) {
3194 struct task_struct *to_wakeup;
3196 to_wakeup = wq_worker_sleeping(prev, cpu);
3198 try_to_wake_up_local(to_wakeup);
3201 switch_count = &prev->nvcsw;
3204 if (task_on_rq_queued(prev))
3205 update_rq_clock(rq);
3207 next = pick_next_task(rq, prev);
3208 clear_tsk_need_resched(prev);
3209 clear_preempt_need_resched();
3210 rq->clock_skip_update = 0;
3212 if (likely(prev != next)) {
3217 trace_sched_switch(preempt, prev, next);
3218 rq = context_switch(rq, prev, next); /* unlocks the rq */
3220 lockdep_unpin_lock(&rq->lock);
3221 raw_spin_unlock_irq(&rq->lock);
3224 balance_callback(rq);
3227 static inline void sched_submit_work(struct task_struct *tsk)
3229 if (!tsk->state || tsk_is_pi_blocked(tsk))
3232 * If we are going to sleep and we have plugged IO queued,
3233 * make sure to submit it to avoid deadlocks.
3235 if (blk_needs_flush_plug(tsk))
3236 blk_schedule_flush_plug(tsk);
3239 asmlinkage __visible void __sched schedule(void)
3241 struct task_struct *tsk = current;
3243 sched_submit_work(tsk);
3247 sched_preempt_enable_no_resched();
3248 } while (need_resched());
3250 EXPORT_SYMBOL(schedule);
3252 #ifdef CONFIG_CONTEXT_TRACKING
3253 asmlinkage __visible void __sched schedule_user(void)
3256 * If we come here after a random call to set_need_resched(),
3257 * or we have been woken up remotely but the IPI has not yet arrived,
3258 * we haven't yet exited the RCU idle mode. Do it here manually until
3259 * we find a better solution.
3261 * NB: There are buggy callers of this function. Ideally we
3262 * should warn if prev_state != CONTEXT_USER, but that will trigger
3263 * too frequently to make sense yet.
3265 enum ctx_state prev_state = exception_enter();
3267 exception_exit(prev_state);
3272 * schedule_preempt_disabled - called with preemption disabled
3274 * Returns with preemption disabled. Note: preempt_count must be 1
3276 void __sched schedule_preempt_disabled(void)
3278 sched_preempt_enable_no_resched();
3283 static void __sched notrace preempt_schedule_common(void)
3286 preempt_disable_notrace();
3288 preempt_enable_no_resched_notrace();
3291 * Check again in case we missed a preemption opportunity
3292 * between schedule and now.
3294 } while (need_resched());
3297 #ifdef CONFIG_PREEMPT
3299 * this is the entry point to schedule() from in-kernel preemption
3300 * off of preempt_enable. Kernel preemptions off return from interrupt
3301 * occur there and call schedule directly.
3303 asmlinkage __visible void __sched notrace preempt_schedule(void)
3306 * If there is a non-zero preempt_count or interrupts are disabled,
3307 * we do not want to preempt the current task. Just return..
3309 if (likely(!preemptible()))
3312 preempt_schedule_common();
3314 NOKPROBE_SYMBOL(preempt_schedule);
3315 EXPORT_SYMBOL(preempt_schedule);
3318 * preempt_schedule_notrace - preempt_schedule called by tracing
3320 * The tracing infrastructure uses preempt_enable_notrace to prevent
3321 * recursion and tracing preempt enabling caused by the tracing
3322 * infrastructure itself. But as tracing can happen in areas coming
3323 * from userspace or just about to enter userspace, a preempt enable
3324 * can occur before user_exit() is called. This will cause the scheduler
3325 * to be called when the system is still in usermode.
3327 * To prevent this, the preempt_enable_notrace will use this function
3328 * instead of preempt_schedule() to exit user context if needed before
3329 * calling the scheduler.
3331 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3333 enum ctx_state prev_ctx;
3335 if (likely(!preemptible()))
3339 preempt_disable_notrace();
3341 * Needs preempt disabled in case user_exit() is traced
3342 * and the tracer calls preempt_enable_notrace() causing
3343 * an infinite recursion.
3345 prev_ctx = exception_enter();
3347 exception_exit(prev_ctx);
3349 preempt_enable_no_resched_notrace();
3350 } while (need_resched());
3352 EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3354 #endif /* CONFIG_PREEMPT */
3357 * this is the entry point to schedule() from kernel preemption
3358 * off of irq context.
3359 * Note, that this is called and return with irqs disabled. This will
3360 * protect us against recursive calling from irq.
3362 asmlinkage __visible void __sched preempt_schedule_irq(void)
3364 enum ctx_state prev_state;
3366 /* Catch callers which need to be fixed */
3367 BUG_ON(preempt_count() || !irqs_disabled());
3369 prev_state = exception_enter();
3375 local_irq_disable();
3376 sched_preempt_enable_no_resched();
3377 } while (need_resched());
3379 exception_exit(prev_state);
3382 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3385 return try_to_wake_up(curr->private, mode, wake_flags);
3387 EXPORT_SYMBOL(default_wake_function);
3389 #ifdef CONFIG_RT_MUTEXES
3392 * rt_mutex_setprio - set the current priority of a task
3394 * @prio: prio value (kernel-internal form)
3396 * This function changes the 'effective' priority of a task. It does
3397 * not touch ->normal_prio like __setscheduler().
3399 * Used by the rt_mutex code to implement priority inheritance
3400 * logic. Call site only calls if the priority of the task changed.
3402 void rt_mutex_setprio(struct task_struct *p, int prio)
3404 int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
3406 const struct sched_class *prev_class;
3408 BUG_ON(prio > MAX_PRIO);
3410 rq = __task_rq_lock(p);
3413 * Idle task boosting is a nono in general. There is one
3414 * exception, when PREEMPT_RT and NOHZ is active:
3416 * The idle task calls get_next_timer_interrupt() and holds
3417 * the timer wheel base->lock on the CPU and another CPU wants
3418 * to access the timer (probably to cancel it). We can safely
3419 * ignore the boosting request, as the idle CPU runs this code
3420 * with interrupts disabled and will complete the lock
3421 * protected section without being interrupted. So there is no
3422 * real need to boost.
3424 if (unlikely(p == rq->idle)) {
3425 WARN_ON(p != rq->curr);
3426 WARN_ON(p->pi_blocked_on);
3430 trace_sched_pi_setprio(p, prio);
3433 if (oldprio == prio)
3434 queue_flag &= ~DEQUEUE_MOVE;
3436 prev_class = p->sched_class;
3437 queued = task_on_rq_queued(p);
3438 running = task_current(rq, p);
3440 dequeue_task(rq, p, queue_flag);
3442 put_prev_task(rq, p);
3445 * Boosting condition are:
3446 * 1. -rt task is running and holds mutex A
3447 * --> -dl task blocks on mutex A
3449 * 2. -dl task is running and holds mutex A
3450 * --> -dl task blocks on mutex A and could preempt the
3453 if (dl_prio(prio)) {
3454 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3455 if (!dl_prio(p->normal_prio) ||
3456 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3457 p->dl.dl_boosted = 1;
3458 queue_flag |= ENQUEUE_REPLENISH;
3460 p->dl.dl_boosted = 0;
3461 p->sched_class = &dl_sched_class;
3462 } else if (rt_prio(prio)) {
3463 if (dl_prio(oldprio))
3464 p->dl.dl_boosted = 0;
3466 queue_flag |= ENQUEUE_HEAD;
3467 p->sched_class = &rt_sched_class;
3469 if (dl_prio(oldprio))
3470 p->dl.dl_boosted = 0;
3471 if (rt_prio(oldprio))
3473 p->sched_class = &fair_sched_class;
3479 p->sched_class->set_curr_task(rq);
3481 enqueue_task(rq, p, queue_flag);
3483 check_class_changed(rq, p, prev_class, oldprio);
3485 preempt_disable(); /* avoid rq from going away on us */
3486 __task_rq_unlock(rq);
3488 balance_callback(rq);
3493 void set_user_nice(struct task_struct *p, long nice)
3495 int old_prio, delta, queued;
3496 unsigned long flags;
3499 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3502 * We have to be careful, if called from sys_setpriority(),
3503 * the task might be in the middle of scheduling on another CPU.
3505 rq = task_rq_lock(p, &flags);
3507 * The RT priorities are set via sched_setscheduler(), but we still
3508 * allow the 'normal' nice value to be set - but as expected
3509 * it wont have any effect on scheduling until the task is
3510 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3512 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3513 p->static_prio = NICE_TO_PRIO(nice);
3516 queued = task_on_rq_queued(p);
3518 dequeue_task(rq, p, DEQUEUE_SAVE);
3520 p->static_prio = NICE_TO_PRIO(nice);
3523 p->prio = effective_prio(p);
3524 delta = p->prio - old_prio;
3527 enqueue_task(rq, p, ENQUEUE_RESTORE);
3529 * If the task increased its priority or is running and
3530 * lowered its priority, then reschedule its CPU:
3532 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3536 task_rq_unlock(rq, p, &flags);
3538 EXPORT_SYMBOL(set_user_nice);
3541 * can_nice - check if a task can reduce its nice value
3545 int can_nice(const struct task_struct *p, const int nice)
3547 /* convert nice value [19,-20] to rlimit style value [1,40] */
3548 int nice_rlim = nice_to_rlimit(nice);
3550 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3551 capable(CAP_SYS_NICE));
3554 #ifdef __ARCH_WANT_SYS_NICE
3557 * sys_nice - change the priority of the current process.
3558 * @increment: priority increment
3560 * sys_setpriority is a more generic, but much slower function that
3561 * does similar things.
3563 SYSCALL_DEFINE1(nice, int, increment)
3568 * Setpriority might change our priority at the same moment.
3569 * We don't have to worry. Conceptually one call occurs first
3570 * and we have a single winner.
3572 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3573 nice = task_nice(current) + increment;
3575 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3576 if (increment < 0 && !can_nice(current, nice))
3579 retval = security_task_setnice(current, nice);
3583 set_user_nice(current, nice);
3590 * task_prio - return the priority value of a given task.
3591 * @p: the task in question.
3593 * Return: The priority value as seen by users in /proc.
3594 * RT tasks are offset by -200. Normal tasks are centered
3595 * around 0, value goes from -16 to +15.
3597 int task_prio(const struct task_struct *p)
3599 return p->prio - MAX_RT_PRIO;
3603 * idle_cpu - is a given cpu idle currently?
3604 * @cpu: the processor in question.
3606 * Return: 1 if the CPU is currently idle. 0 otherwise.
3608 int idle_cpu(int cpu)
3610 struct rq *rq = cpu_rq(cpu);
3612 if (rq->curr != rq->idle)
3619 if (!llist_empty(&rq->wake_list))
3627 * idle_task - return the idle task for a given cpu.
3628 * @cpu: the processor in question.
3630 * Return: The idle task for the cpu @cpu.
3632 struct task_struct *idle_task(int cpu)
3634 return cpu_rq(cpu)->idle;
3638 * find_process_by_pid - find a process with a matching PID value.
3639 * @pid: the pid in question.
3641 * The task of @pid, if found. %NULL otherwise.
3643 static struct task_struct *find_process_by_pid(pid_t pid)
3645 return pid ? find_task_by_vpid(pid) : current;
3649 * This function initializes the sched_dl_entity of a newly becoming
3650 * SCHED_DEADLINE task.
3652 * Only the static values are considered here, the actual runtime and the
3653 * absolute deadline will be properly calculated when the task is enqueued
3654 * for the first time with its new policy.
3657 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3659 struct sched_dl_entity *dl_se = &p->dl;
3661 dl_se->dl_runtime = attr->sched_runtime;
3662 dl_se->dl_deadline = attr->sched_deadline;
3663 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3664 dl_se->flags = attr->sched_flags;
3665 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3668 * Changing the parameters of a task is 'tricky' and we're not doing
3669 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3671 * What we SHOULD do is delay the bandwidth release until the 0-lag
3672 * point. This would include retaining the task_struct until that time
3673 * and change dl_overflow() to not immediately decrement the current
3676 * Instead we retain the current runtime/deadline and let the new
3677 * parameters take effect after the current reservation period lapses.
3678 * This is safe (albeit pessimistic) because the 0-lag point is always
3679 * before the current scheduling deadline.
3681 * We can still have temporary overloads because we do not delay the
3682 * change in bandwidth until that time; so admission control is
3683 * not on the safe side. It does however guarantee tasks will never
3684 * consume more than promised.
3689 * sched_setparam() passes in -1 for its policy, to let the functions
3690 * it calls know not to change it.
3692 #define SETPARAM_POLICY -1
3694 static void __setscheduler_params(struct task_struct *p,
3695 const struct sched_attr *attr)
3697 int policy = attr->sched_policy;
3699 if (policy == SETPARAM_POLICY)
3704 if (dl_policy(policy))
3705 __setparam_dl(p, attr);
3706 else if (fair_policy(policy))
3707 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3710 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3711 * !rt_policy. Always setting this ensures that things like
3712 * getparam()/getattr() don't report silly values for !rt tasks.
3714 p->rt_priority = attr->sched_priority;
3715 p->normal_prio = normal_prio(p);
3719 /* Actually do priority change: must hold pi & rq lock. */
3720 static void __setscheduler(struct rq *rq, struct task_struct *p,
3721 const struct sched_attr *attr, bool keep_boost)
3723 __setscheduler_params(p, attr);
3726 * Keep a potential priority boosting if called from
3727 * sched_setscheduler().
3730 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
3732 p->prio = normal_prio(p);
3734 if (dl_prio(p->prio))
3735 p->sched_class = &dl_sched_class;
3736 else if (rt_prio(p->prio))
3737 p->sched_class = &rt_sched_class;
3739 p->sched_class = &fair_sched_class;
3743 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3745 struct sched_dl_entity *dl_se = &p->dl;
3747 attr->sched_priority = p->rt_priority;
3748 attr->sched_runtime = dl_se->dl_runtime;
3749 attr->sched_deadline = dl_se->dl_deadline;
3750 attr->sched_period = dl_se->dl_period;
3751 attr->sched_flags = dl_se->flags;
3755 * This function validates the new parameters of a -deadline task.
3756 * We ask for the deadline not being zero, and greater or equal
3757 * than the runtime, as well as the period of being zero or
3758 * greater than deadline. Furthermore, we have to be sure that
3759 * user parameters are above the internal resolution of 1us (we
3760 * check sched_runtime only since it is always the smaller one) and
3761 * below 2^63 ns (we have to check both sched_deadline and
3762 * sched_period, as the latter can be zero).
3765 __checkparam_dl(const struct sched_attr *attr)
3768 if (attr->sched_deadline == 0)
3772 * Since we truncate DL_SCALE bits, make sure we're at least
3775 if (attr->sched_runtime < (1ULL << DL_SCALE))
3779 * Since we use the MSB for wrap-around and sign issues, make
3780 * sure it's not set (mind that period can be equal to zero).
3782 if (attr->sched_deadline & (1ULL << 63) ||
3783 attr->sched_period & (1ULL << 63))
3786 /* runtime <= deadline <= period (if period != 0) */
3787 if ((attr->sched_period != 0 &&
3788 attr->sched_period < attr->sched_deadline) ||
3789 attr->sched_deadline < attr->sched_runtime)
3796 * check the target process has a UID that matches the current process's
3798 static bool check_same_owner(struct task_struct *p)
3800 const struct cred *cred = current_cred(), *pcred;
3804 pcred = __task_cred(p);
3805 match = (uid_eq(cred->euid, pcred->euid) ||
3806 uid_eq(cred->euid, pcred->uid));
3811 static bool dl_param_changed(struct task_struct *p,
3812 const struct sched_attr *attr)
3814 struct sched_dl_entity *dl_se = &p->dl;
3816 if (dl_se->dl_runtime != attr->sched_runtime ||
3817 dl_se->dl_deadline != attr->sched_deadline ||
3818 dl_se->dl_period != attr->sched_period ||
3819 dl_se->flags != attr->sched_flags)
3825 static int __sched_setscheduler(struct task_struct *p,
3826 const struct sched_attr *attr,
3829 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3830 MAX_RT_PRIO - 1 - attr->sched_priority;
3831 int retval, oldprio, oldpolicy = -1, queued, running;
3832 int new_effective_prio, policy = attr->sched_policy;
3833 unsigned long flags;
3834 const struct sched_class *prev_class;
3837 int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
3839 /* may grab non-irq protected spin_locks */
3840 BUG_ON(in_interrupt());
3842 /* double check policy once rq lock held */
3844 reset_on_fork = p->sched_reset_on_fork;
3845 policy = oldpolicy = p->policy;
3847 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3849 if (!valid_policy(policy))
3853 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3857 * Valid priorities for SCHED_FIFO and SCHED_RR are
3858 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3859 * SCHED_BATCH and SCHED_IDLE is 0.
3861 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3862 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3864 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3865 (rt_policy(policy) != (attr->sched_priority != 0)))
3869 * Allow unprivileged RT tasks to decrease priority:
3871 if (user && !capable(CAP_SYS_NICE)) {
3872 if (fair_policy(policy)) {
3873 if (attr->sched_nice < task_nice(p) &&
3874 !can_nice(p, attr->sched_nice))
3878 if (rt_policy(policy)) {
3879 unsigned long rlim_rtprio =
3880 task_rlimit(p, RLIMIT_RTPRIO);
3882 /* can't set/change the rt policy */
3883 if (policy != p->policy && !rlim_rtprio)
3886 /* can't increase priority */
3887 if (attr->sched_priority > p->rt_priority &&
3888 attr->sched_priority > rlim_rtprio)
3893 * Can't set/change SCHED_DEADLINE policy at all for now
3894 * (safest behavior); in the future we would like to allow
3895 * unprivileged DL tasks to increase their relative deadline
3896 * or reduce their runtime (both ways reducing utilization)
3898 if (dl_policy(policy))
3902 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3903 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3905 if (idle_policy(p->policy) && !idle_policy(policy)) {
3906 if (!can_nice(p, task_nice(p)))
3910 /* can't change other user's priorities */
3911 if (!check_same_owner(p))
3914 /* Normal users shall not reset the sched_reset_on_fork flag */
3915 if (p->sched_reset_on_fork && !reset_on_fork)
3920 retval = security_task_setscheduler(p);
3926 * make sure no PI-waiters arrive (or leave) while we are
3927 * changing the priority of the task:
3929 * To be able to change p->policy safely, the appropriate
3930 * runqueue lock must be held.
3932 rq = task_rq_lock(p, &flags);
3935 * Changing the policy of the stop threads its a very bad idea
3937 if (p == rq->stop) {
3938 task_rq_unlock(rq, p, &flags);
3943 * If not changing anything there's no need to proceed further,
3944 * but store a possible modification of reset_on_fork.
3946 if (unlikely(policy == p->policy)) {
3947 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3949 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3951 if (dl_policy(policy) && dl_param_changed(p, attr))
3954 p->sched_reset_on_fork = reset_on_fork;
3955 task_rq_unlock(rq, p, &flags);
3961 #ifdef CONFIG_RT_GROUP_SCHED
3963 * Do not allow realtime tasks into groups that have no runtime
3966 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3967 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3968 !task_group_is_autogroup(task_group(p))) {
3969 task_rq_unlock(rq, p, &flags);
3974 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3975 cpumask_t *span = rq->rd->span;
3978 * Don't allow tasks with an affinity mask smaller than
3979 * the entire root_domain to become SCHED_DEADLINE. We
3980 * will also fail if there's no bandwidth available.
3982 if (!cpumask_subset(span, &p->cpus_allowed) ||
3983 rq->rd->dl_bw.bw == 0) {
3984 task_rq_unlock(rq, p, &flags);
3991 /* recheck policy now with rq lock held */
3992 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3993 policy = oldpolicy = -1;
3994 task_rq_unlock(rq, p, &flags);
3999 * If setscheduling to SCHED_DEADLINE (or changing the parameters
4000 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4003 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
4004 task_rq_unlock(rq, p, &flags);
4008 p->sched_reset_on_fork = reset_on_fork;
4013 * Take priority boosted tasks into account. If the new
4014 * effective priority is unchanged, we just store the new
4015 * normal parameters and do not touch the scheduler class and
4016 * the runqueue. This will be done when the task deboost
4019 new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
4020 if (new_effective_prio == oldprio)
4021 queue_flags &= ~DEQUEUE_MOVE;
4024 queued = task_on_rq_queued(p);
4025 running = task_current(rq, p);
4027 dequeue_task(rq, p, queue_flags);
4029 put_prev_task(rq, p);
4031 prev_class = p->sched_class;
4032 __setscheduler(rq, p, attr, pi);
4035 p->sched_class->set_curr_task(rq);
4038 * We enqueue to tail when the priority of a task is
4039 * increased (user space view).
4041 if (oldprio < p->prio)
4042 queue_flags |= ENQUEUE_HEAD;
4044 enqueue_task(rq, p, queue_flags);
4047 check_class_changed(rq, p, prev_class, oldprio);
4048 preempt_disable(); /* avoid rq from going away on us */
4049 task_rq_unlock(rq, p, &flags);
4052 rt_mutex_adjust_pi(p);
4055 * Run balance callbacks after we've adjusted the PI chain.
4057 balance_callback(rq);
4063 static int _sched_setscheduler(struct task_struct *p, int policy,
4064 const struct sched_param *param, bool check)
4066 struct sched_attr attr = {
4067 .sched_policy = policy,
4068 .sched_priority = param->sched_priority,
4069 .sched_nice = PRIO_TO_NICE(p->static_prio),
4072 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4073 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4074 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4075 policy &= ~SCHED_RESET_ON_FORK;
4076 attr.sched_policy = policy;
4079 return __sched_setscheduler(p, &attr, check, true);
4082 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4083 * @p: the task in question.
4084 * @policy: new policy.
4085 * @param: structure containing the new RT priority.
4087 * Return: 0 on success. An error code otherwise.
4089 * NOTE that the task may be already dead.
4091 int sched_setscheduler(struct task_struct *p, int policy,
4092 const struct sched_param *param)
4094 return _sched_setscheduler(p, policy, param, true);
4096 EXPORT_SYMBOL_GPL(sched_setscheduler);
4098 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4100 return __sched_setscheduler(p, attr, true, true);
4102 EXPORT_SYMBOL_GPL(sched_setattr);
4105 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4106 * @p: the task in question.
4107 * @policy: new policy.
4108 * @param: structure containing the new RT priority.
4110 * Just like sched_setscheduler, only don't bother checking if the
4111 * current context has permission. For example, this is needed in
4112 * stop_machine(): we create temporary high priority worker threads,
4113 * but our caller might not have that capability.
4115 * Return: 0 on success. An error code otherwise.
4117 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4118 const struct sched_param *param)
4120 return _sched_setscheduler(p, policy, param, false);
4122 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4125 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4127 struct sched_param lparam;
4128 struct task_struct *p;
4131 if (!param || pid < 0)
4133 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4138 p = find_process_by_pid(pid);
4140 retval = sched_setscheduler(p, policy, &lparam);
4147 * Mimics kernel/events/core.c perf_copy_attr().
4149 static int sched_copy_attr(struct sched_attr __user *uattr,
4150 struct sched_attr *attr)
4155 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4159 * zero the full structure, so that a short copy will be nice.
4161 memset(attr, 0, sizeof(*attr));
4163 ret = get_user(size, &uattr->size);
4167 if (size > PAGE_SIZE) /* silly large */
4170 if (!size) /* abi compat */
4171 size = SCHED_ATTR_SIZE_VER0;
4173 if (size < SCHED_ATTR_SIZE_VER0)
4177 * If we're handed a bigger struct than we know of,
4178 * ensure all the unknown bits are 0 - i.e. new
4179 * user-space does not rely on any kernel feature
4180 * extensions we dont know about yet.
4182 if (size > sizeof(*attr)) {
4183 unsigned char __user *addr;
4184 unsigned char __user *end;
4187 addr = (void __user *)uattr + sizeof(*attr);
4188 end = (void __user *)uattr + size;
4190 for (; addr < end; addr++) {
4191 ret = get_user(val, addr);
4197 size = sizeof(*attr);
4200 ret = copy_from_user(attr, uattr, size);
4205 * XXX: do we want to be lenient like existing syscalls; or do we want
4206 * to be strict and return an error on out-of-bounds values?
4208 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4213 put_user(sizeof(*attr), &uattr->size);
4218 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4219 * @pid: the pid in question.
4220 * @policy: new policy.
4221 * @param: structure containing the new RT priority.
4223 * Return: 0 on success. An error code otherwise.
4225 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4226 struct sched_param __user *, param)
4228 /* negative values for policy are not valid */
4232 return do_sched_setscheduler(pid, policy, param);
4236 * sys_sched_setparam - set/change the RT priority of a thread
4237 * @pid: the pid in question.
4238 * @param: structure containing the new RT priority.
4240 * Return: 0 on success. An error code otherwise.
4242 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4244 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4248 * sys_sched_setattr - same as above, but with extended sched_attr
4249 * @pid: the pid in question.
4250 * @uattr: structure containing the extended parameters.
4251 * @flags: for future extension.
4253 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4254 unsigned int, flags)
4256 struct sched_attr attr;
4257 struct task_struct *p;
4260 if (!uattr || pid < 0 || flags)
4263 retval = sched_copy_attr(uattr, &attr);
4267 if ((int)attr.sched_policy < 0)
4272 p = find_process_by_pid(pid);
4274 retval = sched_setattr(p, &attr);
4281 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4282 * @pid: the pid in question.
4284 * Return: On success, the policy of the thread. Otherwise, a negative error
4287 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4289 struct task_struct *p;
4297 p = find_process_by_pid(pid);
4299 retval = security_task_getscheduler(p);
4302 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4309 * sys_sched_getparam - get the RT priority of a thread
4310 * @pid: the pid in question.
4311 * @param: structure containing the RT priority.
4313 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4316 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4318 struct sched_param lp = { .sched_priority = 0 };
4319 struct task_struct *p;
4322 if (!param || pid < 0)
4326 p = find_process_by_pid(pid);
4331 retval = security_task_getscheduler(p);
4335 if (task_has_rt_policy(p))
4336 lp.sched_priority = p->rt_priority;
4340 * This one might sleep, we cannot do it with a spinlock held ...
4342 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4351 static int sched_read_attr(struct sched_attr __user *uattr,
4352 struct sched_attr *attr,
4357 if (!access_ok(VERIFY_WRITE, uattr, usize))
4361 * If we're handed a smaller struct than we know of,
4362 * ensure all the unknown bits are 0 - i.e. old
4363 * user-space does not get uncomplete information.
4365 if (usize < sizeof(*attr)) {
4366 unsigned char *addr;
4369 addr = (void *)attr + usize;
4370 end = (void *)attr + sizeof(*attr);
4372 for (; addr < end; addr++) {
4380 ret = copy_to_user(uattr, attr, attr->size);
4388 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4389 * @pid: the pid in question.
4390 * @uattr: structure containing the extended parameters.
4391 * @size: sizeof(attr) for fwd/bwd comp.
4392 * @flags: for future extension.
4394 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4395 unsigned int, size, unsigned int, flags)
4397 struct sched_attr attr = {
4398 .size = sizeof(struct sched_attr),
4400 struct task_struct *p;
4403 if (!uattr || pid < 0 || size > PAGE_SIZE ||
4404 size < SCHED_ATTR_SIZE_VER0 || flags)
4408 p = find_process_by_pid(pid);
4413 retval = security_task_getscheduler(p);
4417 attr.sched_policy = p->policy;
4418 if (p->sched_reset_on_fork)
4419 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4420 if (task_has_dl_policy(p))
4421 __getparam_dl(p, &attr);
4422 else if (task_has_rt_policy(p))
4423 attr.sched_priority = p->rt_priority;
4425 attr.sched_nice = task_nice(p);
4429 retval = sched_read_attr(uattr, &attr, size);
4437 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4439 cpumask_var_t cpus_allowed, new_mask;
4440 struct task_struct *p;
4445 p = find_process_by_pid(pid);
4451 /* Prevent p going away */
4455 if (p->flags & PF_NO_SETAFFINITY) {
4459 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4463 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4465 goto out_free_cpus_allowed;
4468 if (!check_same_owner(p)) {
4470 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4472 goto out_free_new_mask;
4477 retval = security_task_setscheduler(p);
4479 goto out_free_new_mask;
4482 cpuset_cpus_allowed(p, cpus_allowed);
4483 cpumask_and(new_mask, in_mask, cpus_allowed);
4486 * Since bandwidth control happens on root_domain basis,
4487 * if admission test is enabled, we only admit -deadline
4488 * tasks allowed to run on all the CPUs in the task's
4492 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4494 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4497 goto out_free_new_mask;
4503 retval = __set_cpus_allowed_ptr(p, new_mask, true);
4506 cpuset_cpus_allowed(p, cpus_allowed);
4507 if (!cpumask_subset(new_mask, cpus_allowed)) {
4509 * We must have raced with a concurrent cpuset
4510 * update. Just reset the cpus_allowed to the
4511 * cpuset's cpus_allowed
4513 cpumask_copy(new_mask, cpus_allowed);
4518 free_cpumask_var(new_mask);
4519 out_free_cpus_allowed:
4520 free_cpumask_var(cpus_allowed);
4526 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4527 struct cpumask *new_mask)
4529 if (len < cpumask_size())
4530 cpumask_clear(new_mask);
4531 else if (len > cpumask_size())
4532 len = cpumask_size();
4534 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4538 * sys_sched_setaffinity - set the cpu affinity of a process
4539 * @pid: pid of the process
4540 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4541 * @user_mask_ptr: user-space pointer to the new cpu mask
4543 * Return: 0 on success. An error code otherwise.
4545 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4546 unsigned long __user *, user_mask_ptr)
4548 cpumask_var_t new_mask;
4551 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4554 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4556 retval = sched_setaffinity(pid, new_mask);
4557 free_cpumask_var(new_mask);
4561 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4563 struct task_struct *p;
4564 unsigned long flags;
4570 p = find_process_by_pid(pid);
4574 retval = security_task_getscheduler(p);
4578 raw_spin_lock_irqsave(&p->pi_lock, flags);
4579 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4580 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4589 * sys_sched_getaffinity - get the cpu affinity of a process
4590 * @pid: pid of the process
4591 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4592 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4594 * Return: 0 on success. An error code otherwise.
4596 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4597 unsigned long __user *, user_mask_ptr)
4602 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4604 if (len & (sizeof(unsigned long)-1))
4607 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4610 ret = sched_getaffinity(pid, mask);
4612 size_t retlen = min_t(size_t, len, cpumask_size());
4614 if (copy_to_user(user_mask_ptr, mask, retlen))
4619 free_cpumask_var(mask);
4625 * sys_sched_yield - yield the current processor to other threads.
4627 * This function yields the current CPU to other tasks. If there are no
4628 * other threads running on this CPU then this function will return.
4632 SYSCALL_DEFINE0(sched_yield)
4634 struct rq *rq = this_rq_lock();
4636 schedstat_inc(rq, yld_count);
4637 current->sched_class->yield_task(rq);
4640 * Since we are going to call schedule() anyway, there's
4641 * no need to preempt or enable interrupts:
4643 __release(rq->lock);
4644 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4645 do_raw_spin_unlock(&rq->lock);
4646 sched_preempt_enable_no_resched();
4653 int __sched _cond_resched(void)
4655 if (should_resched(0)) {
4656 preempt_schedule_common();
4661 EXPORT_SYMBOL(_cond_resched);
4664 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4665 * call schedule, and on return reacquire the lock.
4667 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4668 * operations here to prevent schedule() from being called twice (once via
4669 * spin_unlock(), once by hand).
4671 int __cond_resched_lock(spinlock_t *lock)
4673 int resched = should_resched(PREEMPT_LOCK_OFFSET);
4676 lockdep_assert_held(lock);
4678 if (spin_needbreak(lock) || resched) {
4681 preempt_schedule_common();
4689 EXPORT_SYMBOL(__cond_resched_lock);
4691 int __sched __cond_resched_softirq(void)
4693 BUG_ON(!in_softirq());
4695 if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4697 preempt_schedule_common();
4703 EXPORT_SYMBOL(__cond_resched_softirq);
4706 * yield - yield the current processor to other threads.
4708 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4710 * The scheduler is at all times free to pick the calling task as the most
4711 * eligible task to run, if removing the yield() call from your code breaks
4712 * it, its already broken.
4714 * Typical broken usage is:
4719 * where one assumes that yield() will let 'the other' process run that will
4720 * make event true. If the current task is a SCHED_FIFO task that will never
4721 * happen. Never use yield() as a progress guarantee!!
4723 * If you want to use yield() to wait for something, use wait_event().
4724 * If you want to use yield() to be 'nice' for others, use cond_resched().
4725 * If you still want to use yield(), do not!
4727 void __sched yield(void)
4729 set_current_state(TASK_RUNNING);
4732 EXPORT_SYMBOL(yield);
4735 * yield_to - yield the current processor to another thread in
4736 * your thread group, or accelerate that thread toward the
4737 * processor it's on.
4739 * @preempt: whether task preemption is allowed or not
4741 * It's the caller's job to ensure that the target task struct
4742 * can't go away on us before we can do any checks.
4745 * true (>0) if we indeed boosted the target task.
4746 * false (0) if we failed to boost the target.
4747 * -ESRCH if there's no task to yield to.
4749 int __sched yield_to(struct task_struct *p, bool preempt)
4751 struct task_struct *curr = current;
4752 struct rq *rq, *p_rq;
4753 unsigned long flags;
4756 local_irq_save(flags);
4762 * If we're the only runnable task on the rq and target rq also
4763 * has only one task, there's absolutely no point in yielding.
4765 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4770 double_rq_lock(rq, p_rq);
4771 if (task_rq(p) != p_rq) {
4772 double_rq_unlock(rq, p_rq);
4776 if (!curr->sched_class->yield_to_task)
4779 if (curr->sched_class != p->sched_class)
4782 if (task_running(p_rq, p) || p->state)
4785 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4787 schedstat_inc(rq, yld_count);
4789 * Make p's CPU reschedule; pick_next_entity takes care of
4792 if (preempt && rq != p_rq)
4797 double_rq_unlock(rq, p_rq);
4799 local_irq_restore(flags);
4806 EXPORT_SYMBOL_GPL(yield_to);
4809 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4810 * that process accounting knows that this is a task in IO wait state.
4812 long __sched io_schedule_timeout(long timeout)
4814 int old_iowait = current->in_iowait;
4818 current->in_iowait = 1;
4819 blk_schedule_flush_plug(current);
4821 delayacct_blkio_start();
4823 atomic_inc(&rq->nr_iowait);
4824 ret = schedule_timeout(timeout);
4825 current->in_iowait = old_iowait;
4826 atomic_dec(&rq->nr_iowait);
4827 delayacct_blkio_end();
4831 EXPORT_SYMBOL(io_schedule_timeout);
4834 * sys_sched_get_priority_max - return maximum RT priority.
4835 * @policy: scheduling class.
4837 * Return: On success, this syscall returns the maximum
4838 * rt_priority that can be used by a given scheduling class.
4839 * On failure, a negative error code is returned.
4841 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4848 ret = MAX_USER_RT_PRIO-1;
4850 case SCHED_DEADLINE:
4861 * sys_sched_get_priority_min - return minimum RT priority.
4862 * @policy: scheduling class.
4864 * Return: On success, this syscall returns the minimum
4865 * rt_priority that can be used by a given scheduling class.
4866 * On failure, a negative error code is returned.
4868 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4877 case SCHED_DEADLINE:
4887 * sys_sched_rr_get_interval - return the default timeslice of a process.
4888 * @pid: pid of the process.
4889 * @interval: userspace pointer to the timeslice value.
4891 * this syscall writes the default timeslice value of a given process
4892 * into the user-space timespec buffer. A value of '0' means infinity.
4894 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4897 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4898 struct timespec __user *, interval)
4900 struct task_struct *p;
4901 unsigned int time_slice;
4902 unsigned long flags;
4912 p = find_process_by_pid(pid);
4916 retval = security_task_getscheduler(p);
4920 rq = task_rq_lock(p, &flags);
4922 if (p->sched_class->get_rr_interval)
4923 time_slice = p->sched_class->get_rr_interval(rq, p);
4924 task_rq_unlock(rq, p, &flags);
4927 jiffies_to_timespec(time_slice, &t);
4928 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4936 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4938 void sched_show_task(struct task_struct *p)
4940 unsigned long free = 0;
4942 unsigned long state = p->state;
4945 state = __ffs(state) + 1;
4946 printk(KERN_INFO "%-15.15s %c", p->comm,
4947 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4948 #if BITS_PER_LONG == 32
4949 if (state == TASK_RUNNING)
4950 printk(KERN_CONT " running ");
4952 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4954 if (state == TASK_RUNNING)
4955 printk(KERN_CONT " running task ");
4957 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4959 #ifdef CONFIG_DEBUG_STACK_USAGE
4960 free = stack_not_used(p);
4965 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4967 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4968 task_pid_nr(p), ppid,
4969 (unsigned long)task_thread_info(p)->flags);
4971 print_worker_info(KERN_INFO, p);
4972 show_stack(p, NULL);
4975 void show_state_filter(unsigned long state_filter)
4977 struct task_struct *g, *p;
4979 #if BITS_PER_LONG == 32
4981 " task PC stack pid father\n");
4984 " task PC stack pid father\n");
4987 for_each_process_thread(g, p) {
4989 * reset the NMI-timeout, listing all files on a slow
4990 * console might take a lot of time:
4992 touch_nmi_watchdog();
4993 if (!state_filter || (p->state & state_filter))
4997 touch_all_softlockup_watchdogs();
4999 #ifdef CONFIG_SCHED_DEBUG
5000 sysrq_sched_debug_show();
5004 * Only show locks if all tasks are dumped:
5007 debug_show_all_locks();
5010 void init_idle_bootup_task(struct task_struct *idle)
5012 idle->sched_class = &idle_sched_class;
5016 * init_idle - set up an idle thread for a given CPU
5017 * @idle: task in question
5018 * @cpu: cpu the idle task belongs to
5020 * NOTE: this function does not set the idle thread's NEED_RESCHED
5021 * flag, to make booting more robust.
5023 void init_idle(struct task_struct *idle, int cpu)
5025 struct rq *rq = cpu_rq(cpu);
5026 unsigned long flags;
5028 raw_spin_lock_irqsave(&idle->pi_lock, flags);
5029 raw_spin_lock(&rq->lock);
5031 __sched_fork(0, idle);
5032 idle->state = TASK_RUNNING;
5033 idle->se.exec_start = sched_clock();
5037 * Its possible that init_idle() gets called multiple times on a task,
5038 * in that case do_set_cpus_allowed() will not do the right thing.
5040 * And since this is boot we can forgo the serialization.
5042 set_cpus_allowed_common(idle, cpumask_of(cpu));
5045 * We're having a chicken and egg problem, even though we are
5046 * holding rq->lock, the cpu isn't yet set to this cpu so the
5047 * lockdep check in task_group() will fail.
5049 * Similar case to sched_fork(). / Alternatively we could
5050 * use task_rq_lock() here and obtain the other rq->lock.
5055 __set_task_cpu(idle, cpu);
5058 rq->curr = rq->idle = idle;
5059 idle->on_rq = TASK_ON_RQ_QUEUED;
5063 raw_spin_unlock(&rq->lock);
5064 raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5066 /* Set the preempt count _outside_ the spinlocks! */
5067 init_idle_preempt_count(idle, cpu);
5070 * The idle tasks have their own, simple scheduling class:
5072 idle->sched_class = &idle_sched_class;
5073 ftrace_graph_init_idle_task(idle, cpu);
5074 vtime_init_idle(idle, cpu);
5076 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5080 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5081 const struct cpumask *trial)
5083 int ret = 1, trial_cpus;
5084 struct dl_bw *cur_dl_b;
5085 unsigned long flags;
5087 if (!cpumask_weight(cur))
5090 rcu_read_lock_sched();
5091 cur_dl_b = dl_bw_of(cpumask_any(cur));
5092 trial_cpus = cpumask_weight(trial);
5094 raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
5095 if (cur_dl_b->bw != -1 &&
5096 cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
5098 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5099 rcu_read_unlock_sched();
5104 int task_can_attach(struct task_struct *p,
5105 const struct cpumask *cs_cpus_allowed)
5110 * Kthreads which disallow setaffinity shouldn't be moved
5111 * to a new cpuset; we don't want to change their cpu
5112 * affinity and isolating such threads by their set of
5113 * allowed nodes is unnecessary. Thus, cpusets are not
5114 * applicable for such threads. This prevents checking for
5115 * success of set_cpus_allowed_ptr() on all attached tasks
5116 * before cpus_allowed may be changed.
5118 if (p->flags & PF_NO_SETAFFINITY) {
5124 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5126 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
5131 unsigned long flags;
5133 rcu_read_lock_sched();
5134 dl_b = dl_bw_of(dest_cpu);
5135 raw_spin_lock_irqsave(&dl_b->lock, flags);
5136 cpus = dl_bw_cpus(dest_cpu);
5137 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
5142 * We reserve space for this task in the destination
5143 * root_domain, as we can't fail after this point.
5144 * We will free resources in the source root_domain
5145 * later on (see set_cpus_allowed_dl()).
5147 __dl_add(dl_b, p->dl.dl_bw);
5149 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5150 rcu_read_unlock_sched();
5160 #ifdef CONFIG_NUMA_BALANCING
5161 /* Migrate current task p to target_cpu */
5162 int migrate_task_to(struct task_struct *p, int target_cpu)
5164 struct migration_arg arg = { p, target_cpu };
5165 int curr_cpu = task_cpu(p);
5167 if (curr_cpu == target_cpu)
5170 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
5173 /* TODO: This is not properly updating schedstats */
5175 trace_sched_move_numa(p, curr_cpu, target_cpu);
5176 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5180 * Requeue a task on a given node and accurately track the number of NUMA
5181 * tasks on the runqueues
5183 void sched_setnuma(struct task_struct *p, int nid)
5186 unsigned long flags;
5187 bool queued, running;
5189 rq = task_rq_lock(p, &flags);
5190 queued = task_on_rq_queued(p);
5191 running = task_current(rq, p);
5194 dequeue_task(rq, p, DEQUEUE_SAVE);
5196 put_prev_task(rq, p);
5198 p->numa_preferred_nid = nid;
5201 p->sched_class->set_curr_task(rq);
5203 enqueue_task(rq, p, ENQUEUE_RESTORE);
5204 task_rq_unlock(rq, p, &flags);
5206 #endif /* CONFIG_NUMA_BALANCING */
5208 #ifdef CONFIG_HOTPLUG_CPU
5210 * Ensures that the idle task is using init_mm right before its cpu goes
5213 void idle_task_exit(void)
5215 struct mm_struct *mm = current->active_mm;
5217 BUG_ON(cpu_online(smp_processor_id()));
5219 if (mm != &init_mm) {
5220 switch_mm(mm, &init_mm, current);
5221 finish_arch_post_lock_switch();
5227 * Since this CPU is going 'away' for a while, fold any nr_active delta
5228 * we might have. Assumes we're called after migrate_tasks() so that the
5229 * nr_active count is stable.
5231 * Also see the comment "Global load-average calculations".
5233 static void calc_load_migrate(struct rq *rq)
5235 long delta = calc_load_fold_active(rq);
5237 atomic_long_add(delta, &calc_load_tasks);
5240 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5244 static const struct sched_class fake_sched_class = {
5245 .put_prev_task = put_prev_task_fake,
5248 static struct task_struct fake_task = {
5250 * Avoid pull_{rt,dl}_task()
5252 .prio = MAX_PRIO + 1,
5253 .sched_class = &fake_sched_class,
5257 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5258 * try_to_wake_up()->select_task_rq().
5260 * Called with rq->lock held even though we'er in stop_machine() and
5261 * there's no concurrency possible, we hold the required locks anyway
5262 * because of lock validation efforts.
5264 static void migrate_tasks(struct rq *dead_rq)
5266 struct rq *rq = dead_rq;
5267 struct task_struct *next, *stop = rq->stop;
5271 * Fudge the rq selection such that the below task selection loop
5272 * doesn't get stuck on the currently eligible stop task.
5274 * We're currently inside stop_machine() and the rq is either stuck
5275 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5276 * either way we should never end up calling schedule() until we're
5282 * put_prev_task() and pick_next_task() sched
5283 * class method both need to have an up-to-date
5284 * value of rq->clock[_task]
5286 update_rq_clock(rq);
5290 * There's this thread running, bail when that's the only
5293 if (rq->nr_running == 1)
5297 * pick_next_task assumes pinned rq->lock.
5299 lockdep_pin_lock(&rq->lock);
5300 next = pick_next_task(rq, &fake_task);
5302 next->sched_class->put_prev_task(rq, next);
5305 * Rules for changing task_struct::cpus_allowed are holding
5306 * both pi_lock and rq->lock, such that holding either
5307 * stabilizes the mask.
5309 * Drop rq->lock is not quite as disastrous as it usually is
5310 * because !cpu_active at this point, which means load-balance
5311 * will not interfere. Also, stop-machine.
5313 lockdep_unpin_lock(&rq->lock);
5314 raw_spin_unlock(&rq->lock);
5315 raw_spin_lock(&next->pi_lock);
5316 raw_spin_lock(&rq->lock);
5319 * Since we're inside stop-machine, _nothing_ should have
5320 * changed the task, WARN if weird stuff happened, because in
5321 * that case the above rq->lock drop is a fail too.
5323 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5324 raw_spin_unlock(&next->pi_lock);
5328 /* Find suitable destination for @next, with force if needed. */
5329 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5331 rq = __migrate_task(rq, next, dest_cpu);
5332 if (rq != dead_rq) {
5333 raw_spin_unlock(&rq->lock);
5335 raw_spin_lock(&rq->lock);
5337 raw_spin_unlock(&next->pi_lock);
5342 #endif /* CONFIG_HOTPLUG_CPU */
5344 static void set_rq_online(struct rq *rq)
5347 const struct sched_class *class;
5349 cpumask_set_cpu(rq->cpu, rq->rd->online);
5352 for_each_class(class) {
5353 if (class->rq_online)
5354 class->rq_online(rq);
5359 static void set_rq_offline(struct rq *rq)
5362 const struct sched_class *class;
5364 for_each_class(class) {
5365 if (class->rq_offline)
5366 class->rq_offline(rq);
5369 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5375 * migration_call - callback that gets triggered when a CPU is added.
5376 * Here we can start up the necessary migration thread for the new CPU.
5379 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5381 int cpu = (long)hcpu;
5382 unsigned long flags;
5383 struct rq *rq = cpu_rq(cpu);
5385 switch (action & ~CPU_TASKS_FROZEN) {
5387 case CPU_UP_PREPARE:
5388 rq->calc_load_update = calc_load_update;
5392 /* Update our root-domain */
5393 raw_spin_lock_irqsave(&rq->lock, flags);
5395 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5399 raw_spin_unlock_irqrestore(&rq->lock, flags);
5402 #ifdef CONFIG_HOTPLUG_CPU
5404 sched_ttwu_pending();
5405 /* Update our root-domain */
5406 raw_spin_lock_irqsave(&rq->lock, flags);
5408 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5412 BUG_ON(rq->nr_running != 1); /* the migration thread */
5413 raw_spin_unlock_irqrestore(&rq->lock, flags);
5417 calc_load_migrate(rq);
5422 update_max_interval();
5428 * Register at high priority so that task migration (migrate_all_tasks)
5429 * happens before everything else. This has to be lower priority than
5430 * the notifier in the perf_event subsystem, though.
5432 static struct notifier_block migration_notifier = {
5433 .notifier_call = migration_call,
5434 .priority = CPU_PRI_MIGRATION,
5437 static void set_cpu_rq_start_time(void)
5439 int cpu = smp_processor_id();
5440 struct rq *rq = cpu_rq(cpu);
5441 rq->age_stamp = sched_clock_cpu(cpu);
5444 static int sched_cpu_active(struct notifier_block *nfb,
5445 unsigned long action, void *hcpu)
5447 int cpu = (long)hcpu;
5449 switch (action & ~CPU_TASKS_FROZEN) {
5451 set_cpu_rq_start_time();
5456 * At this point a starting CPU has marked itself as online via
5457 * set_cpu_online(). But it might not yet have marked itself
5458 * as active, which is essential from here on.
5460 set_cpu_active(cpu, true);
5461 stop_machine_unpark(cpu);
5464 case CPU_DOWN_FAILED:
5465 set_cpu_active(cpu, true);
5473 static int sched_cpu_inactive(struct notifier_block *nfb,
5474 unsigned long action, void *hcpu)
5476 switch (action & ~CPU_TASKS_FROZEN) {
5477 case CPU_DOWN_PREPARE:
5478 set_cpu_active((long)hcpu, false);
5485 static int __init migration_init(void)
5487 void *cpu = (void *)(long)smp_processor_id();
5490 /* Initialize migration for the boot CPU */
5491 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5492 BUG_ON(err == NOTIFY_BAD);
5493 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5494 register_cpu_notifier(&migration_notifier);
5496 /* Register cpu active notifiers */
5497 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5498 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5502 early_initcall(migration_init);
5504 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5506 #ifdef CONFIG_SCHED_DEBUG
5508 static __read_mostly int sched_debug_enabled;
5510 static int __init sched_debug_setup(char *str)
5512 sched_debug_enabled = 1;
5516 early_param("sched_debug", sched_debug_setup);
5518 static inline bool sched_debug(void)
5520 return sched_debug_enabled;
5523 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5524 struct cpumask *groupmask)
5526 struct sched_group *group = sd->groups;
5528 cpumask_clear(groupmask);
5530 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5532 if (!(sd->flags & SD_LOAD_BALANCE)) {
5533 printk("does not load-balance\n");
5535 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5540 printk(KERN_CONT "span %*pbl level %s\n",
5541 cpumask_pr_args(sched_domain_span(sd)), sd->name);
5543 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5544 printk(KERN_ERR "ERROR: domain->span does not contain "
5547 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5548 printk(KERN_ERR "ERROR: domain->groups does not contain"
5552 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5556 printk(KERN_ERR "ERROR: group is NULL\n");
5560 if (!cpumask_weight(sched_group_cpus(group))) {
5561 printk(KERN_CONT "\n");
5562 printk(KERN_ERR "ERROR: empty group\n");
5566 if (!(sd->flags & SD_OVERLAP) &&
5567 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5568 printk(KERN_CONT "\n");
5569 printk(KERN_ERR "ERROR: repeated CPUs\n");
5573 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5575 printk(KERN_CONT " %*pbl",
5576 cpumask_pr_args(sched_group_cpus(group)));
5577 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5578 printk(KERN_CONT " (cpu_capacity = %d)",
5579 group->sgc->capacity);
5582 group = group->next;
5583 } while (group != sd->groups);
5584 printk(KERN_CONT "\n");
5586 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5587 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5590 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5591 printk(KERN_ERR "ERROR: parent span is not a superset "
5592 "of domain->span\n");
5596 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5600 if (!sched_debug_enabled)
5604 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5608 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5611 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5619 #else /* !CONFIG_SCHED_DEBUG */
5620 # define sched_domain_debug(sd, cpu) do { } while (0)
5621 static inline bool sched_debug(void)
5625 #endif /* CONFIG_SCHED_DEBUG */
5627 static int sd_degenerate(struct sched_domain *sd)
5629 if (cpumask_weight(sched_domain_span(sd)) == 1)
5632 /* Following flags need at least 2 groups */
5633 if (sd->flags & (SD_LOAD_BALANCE |
5634 SD_BALANCE_NEWIDLE |
5637 SD_SHARE_CPUCAPACITY |
5638 SD_SHARE_PKG_RESOURCES |
5639 SD_SHARE_POWERDOMAIN)) {
5640 if (sd->groups != sd->groups->next)
5644 /* Following flags don't use groups */
5645 if (sd->flags & (SD_WAKE_AFFINE))
5652 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5654 unsigned long cflags = sd->flags, pflags = parent->flags;
5656 if (sd_degenerate(parent))
5659 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5662 /* Flags needing groups don't count if only 1 group in parent */
5663 if (parent->groups == parent->groups->next) {
5664 pflags &= ~(SD_LOAD_BALANCE |
5665 SD_BALANCE_NEWIDLE |
5668 SD_SHARE_CPUCAPACITY |
5669 SD_SHARE_PKG_RESOURCES |
5671 SD_SHARE_POWERDOMAIN);
5672 if (nr_node_ids == 1)
5673 pflags &= ~SD_SERIALIZE;
5675 if (~cflags & pflags)
5681 static void free_rootdomain(struct rcu_head *rcu)
5683 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5685 cpupri_cleanup(&rd->cpupri);
5686 cpudl_cleanup(&rd->cpudl);
5687 free_cpumask_var(rd->dlo_mask);
5688 free_cpumask_var(rd->rto_mask);
5689 free_cpumask_var(rd->online);
5690 free_cpumask_var(rd->span);
5694 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5696 struct root_domain *old_rd = NULL;
5697 unsigned long flags;
5699 raw_spin_lock_irqsave(&rq->lock, flags);
5704 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5707 cpumask_clear_cpu(rq->cpu, old_rd->span);
5710 * If we dont want to free the old_rd yet then
5711 * set old_rd to NULL to skip the freeing later
5714 if (!atomic_dec_and_test(&old_rd->refcount))
5718 atomic_inc(&rd->refcount);
5721 cpumask_set_cpu(rq->cpu, rd->span);
5722 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5725 raw_spin_unlock_irqrestore(&rq->lock, flags);
5728 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5731 static int init_rootdomain(struct root_domain *rd)
5733 memset(rd, 0, sizeof(*rd));
5735 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5737 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5739 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5741 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5744 init_dl_bw(&rd->dl_bw);
5745 if (cpudl_init(&rd->cpudl) != 0)
5748 if (cpupri_init(&rd->cpupri) != 0)
5753 free_cpumask_var(rd->rto_mask);
5755 free_cpumask_var(rd->dlo_mask);
5757 free_cpumask_var(rd->online);
5759 free_cpumask_var(rd->span);
5765 * By default the system creates a single root-domain with all cpus as
5766 * members (mimicking the global state we have today).
5768 struct root_domain def_root_domain;
5770 static void init_defrootdomain(void)
5772 init_rootdomain(&def_root_domain);
5774 atomic_set(&def_root_domain.refcount, 1);
5777 static struct root_domain *alloc_rootdomain(void)
5779 struct root_domain *rd;
5781 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5785 if (init_rootdomain(rd) != 0) {
5793 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5795 struct sched_group *tmp, *first;
5804 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5809 } while (sg != first);
5812 static void free_sched_domain(struct rcu_head *rcu)
5814 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5817 * If its an overlapping domain it has private groups, iterate and
5820 if (sd->flags & SD_OVERLAP) {
5821 free_sched_groups(sd->groups, 1);
5822 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5823 kfree(sd->groups->sgc);
5829 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5831 call_rcu(&sd->rcu, free_sched_domain);
5834 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5836 for (; sd; sd = sd->parent)
5837 destroy_sched_domain(sd, cpu);
5841 * Keep a special pointer to the highest sched_domain that has
5842 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5843 * allows us to avoid some pointer chasing select_idle_sibling().
5845 * Also keep a unique ID per domain (we use the first cpu number in
5846 * the cpumask of the domain), this allows us to quickly tell if
5847 * two cpus are in the same cache domain, see cpus_share_cache().
5849 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5850 DEFINE_PER_CPU(int, sd_llc_size);
5851 DEFINE_PER_CPU(int, sd_llc_id);
5852 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5853 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5854 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5856 static void update_top_cache_domain(int cpu)
5858 struct sched_domain *sd;
5859 struct sched_domain *busy_sd = NULL;
5863 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5865 id = cpumask_first(sched_domain_span(sd));
5866 size = cpumask_weight(sched_domain_span(sd));
5867 busy_sd = sd->parent; /* sd_busy */
5869 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5871 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5872 per_cpu(sd_llc_size, cpu) = size;
5873 per_cpu(sd_llc_id, cpu) = id;
5875 sd = lowest_flag_domain(cpu, SD_NUMA);
5876 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5878 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5879 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5883 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5884 * hold the hotplug lock.
5887 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5889 struct rq *rq = cpu_rq(cpu);
5890 struct sched_domain *tmp;
5892 /* Remove the sched domains which do not contribute to scheduling. */
5893 for (tmp = sd; tmp; ) {
5894 struct sched_domain *parent = tmp->parent;
5898 if (sd_parent_degenerate(tmp, parent)) {
5899 tmp->parent = parent->parent;
5901 parent->parent->child = tmp;
5903 * Transfer SD_PREFER_SIBLING down in case of a
5904 * degenerate parent; the spans match for this
5905 * so the property transfers.
5907 if (parent->flags & SD_PREFER_SIBLING)
5908 tmp->flags |= SD_PREFER_SIBLING;
5909 destroy_sched_domain(parent, cpu);
5914 if (sd && sd_degenerate(sd)) {
5917 destroy_sched_domain(tmp, cpu);
5922 sched_domain_debug(sd, cpu);
5924 rq_attach_root(rq, rd);
5926 rcu_assign_pointer(rq->sd, sd);
5927 destroy_sched_domains(tmp, cpu);
5929 update_top_cache_domain(cpu);
5932 /* Setup the mask of cpus configured for isolated domains */
5933 static int __init isolated_cpu_setup(char *str)
5937 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5938 ret = cpulist_parse(str, cpu_isolated_map);
5940 pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
5945 __setup("isolcpus=", isolated_cpu_setup);
5948 struct sched_domain ** __percpu sd;
5949 struct root_domain *rd;
5960 * Build an iteration mask that can exclude certain CPUs from the upwards
5963 * Asymmetric node setups can result in situations where the domain tree is of
5964 * unequal depth, make sure to skip domains that already cover the entire
5967 * In that case build_sched_domains() will have terminated the iteration early
5968 * and our sibling sd spans will be empty. Domains should always include the
5969 * cpu they're built on, so check that.
5972 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5974 const struct cpumask *span = sched_domain_span(sd);
5975 struct sd_data *sdd = sd->private;
5976 struct sched_domain *sibling;
5979 for_each_cpu(i, span) {
5980 sibling = *per_cpu_ptr(sdd->sd, i);
5981 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5984 cpumask_set_cpu(i, sched_group_mask(sg));
5989 * Return the canonical balance cpu for this group, this is the first cpu
5990 * of this group that's also in the iteration mask.
5992 int group_balance_cpu(struct sched_group *sg)
5994 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5998 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
6000 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
6001 const struct cpumask *span = sched_domain_span(sd);
6002 struct cpumask *covered = sched_domains_tmpmask;
6003 struct sd_data *sdd = sd->private;
6004 struct sched_domain *sibling;
6007 cpumask_clear(covered);
6009 for_each_cpu(i, span) {
6010 struct cpumask *sg_span;
6012 if (cpumask_test_cpu(i, covered))
6015 sibling = *per_cpu_ptr(sdd->sd, i);
6017 /* See the comment near build_group_mask(). */
6018 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6021 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6022 GFP_KERNEL, cpu_to_node(cpu));
6027 sg_span = sched_group_cpus(sg);
6029 cpumask_copy(sg_span, sched_domain_span(sibling->child));
6031 cpumask_set_cpu(i, sg_span);
6033 cpumask_or(covered, covered, sg_span);
6035 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
6036 if (atomic_inc_return(&sg->sgc->ref) == 1)
6037 build_group_mask(sd, sg);
6040 * Initialize sgc->capacity such that even if we mess up the
6041 * domains and no possible iteration will get us here, we won't
6044 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6047 * Make sure the first group of this domain contains the
6048 * canonical balance cpu. Otherwise the sched_domain iteration
6049 * breaks. See update_sg_lb_stats().
6051 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
6052 group_balance_cpu(sg) == cpu)
6062 sd->groups = groups;
6067 free_sched_groups(first, 0);
6072 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
6074 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6075 struct sched_domain *child = sd->child;
6078 cpu = cpumask_first(sched_domain_span(child));
6081 *sg = *per_cpu_ptr(sdd->sg, cpu);
6082 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
6083 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6090 * build_sched_groups will build a circular linked list of the groups
6091 * covered by the given span, and will set each group's ->cpumask correctly,
6092 * and ->cpu_capacity to 0.
6094 * Assumes the sched_domain tree is fully constructed
6097 build_sched_groups(struct sched_domain *sd, int cpu)
6099 struct sched_group *first = NULL, *last = NULL;
6100 struct sd_data *sdd = sd->private;
6101 const struct cpumask *span = sched_domain_span(sd);
6102 struct cpumask *covered;
6105 get_group(cpu, sdd, &sd->groups);
6106 atomic_inc(&sd->groups->ref);
6108 if (cpu != cpumask_first(span))
6111 lockdep_assert_held(&sched_domains_mutex);
6112 covered = sched_domains_tmpmask;
6114 cpumask_clear(covered);
6116 for_each_cpu(i, span) {
6117 struct sched_group *sg;
6120 if (cpumask_test_cpu(i, covered))
6123 group = get_group(i, sdd, &sg);
6124 cpumask_setall(sched_group_mask(sg));
6126 for_each_cpu(j, span) {
6127 if (get_group(j, sdd, NULL) != group)
6130 cpumask_set_cpu(j, covered);
6131 cpumask_set_cpu(j, sched_group_cpus(sg));
6146 * Initialize sched groups cpu_capacity.
6148 * cpu_capacity indicates the capacity of sched group, which is used while
6149 * distributing the load between different sched groups in a sched domain.
6150 * Typically cpu_capacity for all the groups in a sched domain will be same
6151 * unless there are asymmetries in the topology. If there are asymmetries,
6152 * group having more cpu_capacity will pickup more load compared to the
6153 * group having less cpu_capacity.
6155 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6157 struct sched_group *sg = sd->groups;
6162 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
6164 } while (sg != sd->groups);
6166 if (cpu != group_balance_cpu(sg))
6169 update_group_capacity(sd, cpu);
6170 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6174 * Initializers for schedule domains
6175 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6178 static int default_relax_domain_level = -1;
6179 int sched_domain_level_max;
6181 static int __init setup_relax_domain_level(char *str)
6183 if (kstrtoint(str, 0, &default_relax_domain_level))
6184 pr_warn("Unable to set relax_domain_level\n");
6188 __setup("relax_domain_level=", setup_relax_domain_level);
6190 static void set_domain_attribute(struct sched_domain *sd,
6191 struct sched_domain_attr *attr)
6195 if (!attr || attr->relax_domain_level < 0) {
6196 if (default_relax_domain_level < 0)
6199 request = default_relax_domain_level;
6201 request = attr->relax_domain_level;
6202 if (request < sd->level) {
6203 /* turn off idle balance on this domain */
6204 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6206 /* turn on idle balance on this domain */
6207 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6211 static void __sdt_free(const struct cpumask *cpu_map);
6212 static int __sdt_alloc(const struct cpumask *cpu_map);
6214 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6215 const struct cpumask *cpu_map)
6219 if (!atomic_read(&d->rd->refcount))
6220 free_rootdomain(&d->rd->rcu); /* fall through */
6222 free_percpu(d->sd); /* fall through */
6224 __sdt_free(cpu_map); /* fall through */
6230 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6231 const struct cpumask *cpu_map)
6233 memset(d, 0, sizeof(*d));
6235 if (__sdt_alloc(cpu_map))
6236 return sa_sd_storage;
6237 d->sd = alloc_percpu(struct sched_domain *);
6239 return sa_sd_storage;
6240 d->rd = alloc_rootdomain();
6243 return sa_rootdomain;
6247 * NULL the sd_data elements we've used to build the sched_domain and
6248 * sched_group structure so that the subsequent __free_domain_allocs()
6249 * will not free the data we're using.
6251 static void claim_allocations(int cpu, struct sched_domain *sd)
6253 struct sd_data *sdd = sd->private;
6255 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6256 *per_cpu_ptr(sdd->sd, cpu) = NULL;
6258 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6259 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6261 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6262 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6266 static int sched_domains_numa_levels;
6267 enum numa_topology_type sched_numa_topology_type;
6268 static int *sched_domains_numa_distance;
6269 int sched_max_numa_distance;
6270 static struct cpumask ***sched_domains_numa_masks;
6271 static int sched_domains_curr_level;
6275 * SD_flags allowed in topology descriptions.
6277 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6278 * SD_SHARE_PKG_RESOURCES - describes shared caches
6279 * SD_NUMA - describes NUMA topologies
6280 * SD_SHARE_POWERDOMAIN - describes shared power domain
6283 * SD_ASYM_PACKING - describes SMT quirks
6285 #define TOPOLOGY_SD_FLAGS \
6286 (SD_SHARE_CPUCAPACITY | \
6287 SD_SHARE_PKG_RESOURCES | \
6290 SD_SHARE_POWERDOMAIN)
6292 static struct sched_domain *
6293 sd_init(struct sched_domain_topology_level *tl, int cpu)
6295 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6296 int sd_weight, sd_flags = 0;
6300 * Ugly hack to pass state to sd_numa_mask()...
6302 sched_domains_curr_level = tl->numa_level;
6305 sd_weight = cpumask_weight(tl->mask(cpu));
6308 sd_flags = (*tl->sd_flags)();
6309 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6310 "wrong sd_flags in topology description\n"))
6311 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6313 *sd = (struct sched_domain){
6314 .min_interval = sd_weight,
6315 .max_interval = 2*sd_weight,
6317 .imbalance_pct = 125,
6319 .cache_nice_tries = 0,
6326 .flags = 1*SD_LOAD_BALANCE
6327 | 1*SD_BALANCE_NEWIDLE
6332 | 0*SD_SHARE_CPUCAPACITY
6333 | 0*SD_SHARE_PKG_RESOURCES
6335 | 0*SD_PREFER_SIBLING
6340 .last_balance = jiffies,
6341 .balance_interval = sd_weight,
6343 .max_newidle_lb_cost = 0,
6344 .next_decay_max_lb_cost = jiffies,
6345 #ifdef CONFIG_SCHED_DEBUG
6351 * Convert topological properties into behaviour.
6354 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6355 sd->flags |= SD_PREFER_SIBLING;
6356 sd->imbalance_pct = 110;
6357 sd->smt_gain = 1178; /* ~15% */
6359 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6360 sd->imbalance_pct = 117;
6361 sd->cache_nice_tries = 1;
6365 } else if (sd->flags & SD_NUMA) {
6366 sd->cache_nice_tries = 2;
6370 sd->flags |= SD_SERIALIZE;
6371 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6372 sd->flags &= ~(SD_BALANCE_EXEC |
6379 sd->flags |= SD_PREFER_SIBLING;
6380 sd->cache_nice_tries = 1;
6385 sd->private = &tl->data;
6391 * Topology list, bottom-up.
6393 static struct sched_domain_topology_level default_topology[] = {
6394 #ifdef CONFIG_SCHED_SMT
6395 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6397 #ifdef CONFIG_SCHED_MC
6398 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6400 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6404 static struct sched_domain_topology_level *sched_domain_topology =
6407 #define for_each_sd_topology(tl) \
6408 for (tl = sched_domain_topology; tl->mask; tl++)
6410 void set_sched_topology(struct sched_domain_topology_level *tl)
6412 sched_domain_topology = tl;
6417 static const struct cpumask *sd_numa_mask(int cpu)
6419 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6422 static void sched_numa_warn(const char *str)
6424 static int done = false;
6432 printk(KERN_WARNING "ERROR: %s\n\n", str);
6434 for (i = 0; i < nr_node_ids; i++) {
6435 printk(KERN_WARNING " ");
6436 for (j = 0; j < nr_node_ids; j++)
6437 printk(KERN_CONT "%02d ", node_distance(i,j));
6438 printk(KERN_CONT "\n");
6440 printk(KERN_WARNING "\n");
6443 bool find_numa_distance(int distance)
6447 if (distance == node_distance(0, 0))
6450 for (i = 0; i < sched_domains_numa_levels; i++) {
6451 if (sched_domains_numa_distance[i] == distance)
6459 * A system can have three types of NUMA topology:
6460 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6461 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6462 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6464 * The difference between a glueless mesh topology and a backplane
6465 * topology lies in whether communication between not directly
6466 * connected nodes goes through intermediary nodes (where programs
6467 * could run), or through backplane controllers. This affects
6468 * placement of programs.
6470 * The type of topology can be discerned with the following tests:
6471 * - If the maximum distance between any nodes is 1 hop, the system
6472 * is directly connected.
6473 * - If for two nodes A and B, located N > 1 hops away from each other,
6474 * there is an intermediary node C, which is < N hops away from both
6475 * nodes A and B, the system is a glueless mesh.
6477 static void init_numa_topology_type(void)
6481 n = sched_max_numa_distance;
6483 if (sched_domains_numa_levels <= 1) {
6484 sched_numa_topology_type = NUMA_DIRECT;
6488 for_each_online_node(a) {
6489 for_each_online_node(b) {
6490 /* Find two nodes furthest removed from each other. */
6491 if (node_distance(a, b) < n)
6494 /* Is there an intermediary node between a and b? */
6495 for_each_online_node(c) {
6496 if (node_distance(a, c) < n &&
6497 node_distance(b, c) < n) {
6498 sched_numa_topology_type =
6504 sched_numa_topology_type = NUMA_BACKPLANE;
6510 static void sched_init_numa(void)
6512 int next_distance, curr_distance = node_distance(0, 0);
6513 struct sched_domain_topology_level *tl;
6517 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6518 if (!sched_domains_numa_distance)
6522 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6523 * unique distances in the node_distance() table.
6525 * Assumes node_distance(0,j) includes all distances in
6526 * node_distance(i,j) in order to avoid cubic time.
6528 next_distance = curr_distance;
6529 for (i = 0; i < nr_node_ids; i++) {
6530 for (j = 0; j < nr_node_ids; j++) {
6531 for (k = 0; k < nr_node_ids; k++) {
6532 int distance = node_distance(i, k);
6534 if (distance > curr_distance &&
6535 (distance < next_distance ||
6536 next_distance == curr_distance))
6537 next_distance = distance;
6540 * While not a strong assumption it would be nice to know
6541 * about cases where if node A is connected to B, B is not
6542 * equally connected to A.
6544 if (sched_debug() && node_distance(k, i) != distance)
6545 sched_numa_warn("Node-distance not symmetric");
6547 if (sched_debug() && i && !find_numa_distance(distance))
6548 sched_numa_warn("Node-0 not representative");
6550 if (next_distance != curr_distance) {
6551 sched_domains_numa_distance[level++] = next_distance;
6552 sched_domains_numa_levels = level;
6553 curr_distance = next_distance;
6558 * In case of sched_debug() we verify the above assumption.
6568 * 'level' contains the number of unique distances, excluding the
6569 * identity distance node_distance(i,i).
6571 * The sched_domains_numa_distance[] array includes the actual distance
6576 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6577 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6578 * the array will contain less then 'level' members. This could be
6579 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6580 * in other functions.
6582 * We reset it to 'level' at the end of this function.
6584 sched_domains_numa_levels = 0;
6586 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6587 if (!sched_domains_numa_masks)
6591 * Now for each level, construct a mask per node which contains all
6592 * cpus of nodes that are that many hops away from us.
6594 for (i = 0; i < level; i++) {
6595 sched_domains_numa_masks[i] =
6596 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6597 if (!sched_domains_numa_masks[i])
6600 for (j = 0; j < nr_node_ids; j++) {
6601 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6605 sched_domains_numa_masks[i][j] = mask;
6608 if (node_distance(j, k) > sched_domains_numa_distance[i])
6611 cpumask_or(mask, mask, cpumask_of_node(k));
6616 /* Compute default topology size */
6617 for (i = 0; sched_domain_topology[i].mask; i++);
6619 tl = kzalloc((i + level + 1) *
6620 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6625 * Copy the default topology bits..
6627 for (i = 0; sched_domain_topology[i].mask; i++)
6628 tl[i] = sched_domain_topology[i];
6631 * .. and append 'j' levels of NUMA goodness.
6633 for (j = 0; j < level; i++, j++) {
6634 tl[i] = (struct sched_domain_topology_level){
6635 .mask = sd_numa_mask,
6636 .sd_flags = cpu_numa_flags,
6637 .flags = SDTL_OVERLAP,
6643 sched_domain_topology = tl;
6645 sched_domains_numa_levels = level;
6646 sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6648 init_numa_topology_type();
6651 static void sched_domains_numa_masks_set(int cpu)
6654 int node = cpu_to_node(cpu);
6656 for (i = 0; i < sched_domains_numa_levels; i++) {
6657 for (j = 0; j < nr_node_ids; j++) {
6658 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6659 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6664 static void sched_domains_numa_masks_clear(int cpu)
6667 for (i = 0; i < sched_domains_numa_levels; i++) {
6668 for (j = 0; j < nr_node_ids; j++)
6669 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6674 * Update sched_domains_numa_masks[level][node] array when new cpus
6677 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6678 unsigned long action,
6681 int cpu = (long)hcpu;
6683 switch (action & ~CPU_TASKS_FROZEN) {
6685 sched_domains_numa_masks_set(cpu);
6689 sched_domains_numa_masks_clear(cpu);
6699 static inline void sched_init_numa(void)
6703 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6704 unsigned long action,
6709 #endif /* CONFIG_NUMA */
6711 static int __sdt_alloc(const struct cpumask *cpu_map)
6713 struct sched_domain_topology_level *tl;
6716 for_each_sd_topology(tl) {
6717 struct sd_data *sdd = &tl->data;
6719 sdd->sd = alloc_percpu(struct sched_domain *);
6723 sdd->sg = alloc_percpu(struct sched_group *);
6727 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6731 for_each_cpu(j, cpu_map) {
6732 struct sched_domain *sd;
6733 struct sched_group *sg;
6734 struct sched_group_capacity *sgc;
6736 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6737 GFP_KERNEL, cpu_to_node(j));
6741 *per_cpu_ptr(sdd->sd, j) = sd;
6743 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6744 GFP_KERNEL, cpu_to_node(j));
6750 *per_cpu_ptr(sdd->sg, j) = sg;
6752 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6753 GFP_KERNEL, cpu_to_node(j));
6757 *per_cpu_ptr(sdd->sgc, j) = sgc;
6764 static void __sdt_free(const struct cpumask *cpu_map)
6766 struct sched_domain_topology_level *tl;
6769 for_each_sd_topology(tl) {
6770 struct sd_data *sdd = &tl->data;
6772 for_each_cpu(j, cpu_map) {
6773 struct sched_domain *sd;
6776 sd = *per_cpu_ptr(sdd->sd, j);
6777 if (sd && (sd->flags & SD_OVERLAP))
6778 free_sched_groups(sd->groups, 0);
6779 kfree(*per_cpu_ptr(sdd->sd, j));
6783 kfree(*per_cpu_ptr(sdd->sg, j));
6785 kfree(*per_cpu_ptr(sdd->sgc, j));
6787 free_percpu(sdd->sd);
6789 free_percpu(sdd->sg);
6791 free_percpu(sdd->sgc);
6796 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6797 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6798 struct sched_domain *child, int cpu)
6800 struct sched_domain *sd = sd_init(tl, cpu);
6804 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6806 sd->level = child->level + 1;
6807 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6811 if (!cpumask_subset(sched_domain_span(child),
6812 sched_domain_span(sd))) {
6813 pr_err("BUG: arch topology borken\n");
6814 #ifdef CONFIG_SCHED_DEBUG
6815 pr_err(" the %s domain not a subset of the %s domain\n",
6816 child->name, sd->name);
6818 /* Fixup, ensure @sd has at least @child cpus. */
6819 cpumask_or(sched_domain_span(sd),
6820 sched_domain_span(sd),
6821 sched_domain_span(child));
6825 set_domain_attribute(sd, attr);
6831 * Build sched domains for a given set of cpus and attach the sched domains
6832 * to the individual cpus
6834 static int build_sched_domains(const struct cpumask *cpu_map,
6835 struct sched_domain_attr *attr)
6837 enum s_alloc alloc_state;
6838 struct sched_domain *sd;
6840 int i, ret = -ENOMEM;
6842 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6843 if (alloc_state != sa_rootdomain)
6846 /* Set up domains for cpus specified by the cpu_map. */
6847 for_each_cpu(i, cpu_map) {
6848 struct sched_domain_topology_level *tl;
6851 for_each_sd_topology(tl) {
6852 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6853 if (tl == sched_domain_topology)
6854 *per_cpu_ptr(d.sd, i) = sd;
6855 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6856 sd->flags |= SD_OVERLAP;
6857 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6862 /* Build the groups for the domains */
6863 for_each_cpu(i, cpu_map) {
6864 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6865 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6866 if (sd->flags & SD_OVERLAP) {
6867 if (build_overlap_sched_groups(sd, i))
6870 if (build_sched_groups(sd, i))
6876 /* Calculate CPU capacity for physical packages and nodes */
6877 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6878 if (!cpumask_test_cpu(i, cpu_map))
6881 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6882 claim_allocations(i, sd);
6883 init_sched_groups_capacity(i, sd);
6887 /* Attach the domains */
6889 for_each_cpu(i, cpu_map) {
6890 sd = *per_cpu_ptr(d.sd, i);
6891 cpu_attach_domain(sd, d.rd, i);
6897 __free_domain_allocs(&d, alloc_state, cpu_map);
6901 static cpumask_var_t *doms_cur; /* current sched domains */
6902 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6903 static struct sched_domain_attr *dattr_cur;
6904 /* attribues of custom domains in 'doms_cur' */
6907 * Special case: If a kmalloc of a doms_cur partition (array of
6908 * cpumask) fails, then fallback to a single sched domain,
6909 * as determined by the single cpumask fallback_doms.
6911 static cpumask_var_t fallback_doms;
6914 * arch_update_cpu_topology lets virtualized architectures update the
6915 * cpu core maps. It is supposed to return 1 if the topology changed
6916 * or 0 if it stayed the same.
6918 int __weak arch_update_cpu_topology(void)
6923 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6926 cpumask_var_t *doms;
6928 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6931 for (i = 0; i < ndoms; i++) {
6932 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6933 free_sched_domains(doms, i);
6940 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6943 for (i = 0; i < ndoms; i++)
6944 free_cpumask_var(doms[i]);
6949 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6950 * For now this just excludes isolated cpus, but could be used to
6951 * exclude other special cases in the future.
6953 static int init_sched_domains(const struct cpumask *cpu_map)
6957 arch_update_cpu_topology();
6959 doms_cur = alloc_sched_domains(ndoms_cur);
6961 doms_cur = &fallback_doms;
6962 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6963 err = build_sched_domains(doms_cur[0], NULL);
6964 register_sched_domain_sysctl();
6970 * Detach sched domains from a group of cpus specified in cpu_map
6971 * These cpus will now be attached to the NULL domain
6973 static void detach_destroy_domains(const struct cpumask *cpu_map)
6978 for_each_cpu(i, cpu_map)
6979 cpu_attach_domain(NULL, &def_root_domain, i);
6983 /* handle null as "default" */
6984 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6985 struct sched_domain_attr *new, int idx_new)
6987 struct sched_domain_attr tmp;
6994 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6995 new ? (new + idx_new) : &tmp,
6996 sizeof(struct sched_domain_attr));
7000 * Partition sched domains as specified by the 'ndoms_new'
7001 * cpumasks in the array doms_new[] of cpumasks. This compares
7002 * doms_new[] to the current sched domain partitioning, doms_cur[].
7003 * It destroys each deleted domain and builds each new domain.
7005 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7006 * The masks don't intersect (don't overlap.) We should setup one
7007 * sched domain for each mask. CPUs not in any of the cpumasks will
7008 * not be load balanced. If the same cpumask appears both in the
7009 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7012 * The passed in 'doms_new' should be allocated using
7013 * alloc_sched_domains. This routine takes ownership of it and will
7014 * free_sched_domains it when done with it. If the caller failed the
7015 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7016 * and partition_sched_domains() will fallback to the single partition
7017 * 'fallback_doms', it also forces the domains to be rebuilt.
7019 * If doms_new == NULL it will be replaced with cpu_online_mask.
7020 * ndoms_new == 0 is a special case for destroying existing domains,
7021 * and it will not create the default domain.
7023 * Call with hotplug lock held
7025 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7026 struct sched_domain_attr *dattr_new)
7031 mutex_lock(&sched_domains_mutex);
7033 /* always unregister in case we don't destroy any domains */
7034 unregister_sched_domain_sysctl();
7036 /* Let architecture update cpu core mappings. */
7037 new_topology = arch_update_cpu_topology();
7039 n = doms_new ? ndoms_new : 0;
7041 /* Destroy deleted domains */
7042 for (i = 0; i < ndoms_cur; i++) {
7043 for (j = 0; j < n && !new_topology; j++) {
7044 if (cpumask_equal(doms_cur[i], doms_new[j])
7045 && dattrs_equal(dattr_cur, i, dattr_new, j))
7048 /* no match - a current sched domain not in new doms_new[] */
7049 detach_destroy_domains(doms_cur[i]);
7055 if (doms_new == NULL) {
7057 doms_new = &fallback_doms;
7058 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7059 WARN_ON_ONCE(dattr_new);
7062 /* Build new domains */
7063 for (i = 0; i < ndoms_new; i++) {
7064 for (j = 0; j < n && !new_topology; j++) {
7065 if (cpumask_equal(doms_new[i], doms_cur[j])
7066 && dattrs_equal(dattr_new, i, dattr_cur, j))
7069 /* no match - add a new doms_new */
7070 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
7075 /* Remember the new sched domains */
7076 if (doms_cur != &fallback_doms)
7077 free_sched_domains(doms_cur, ndoms_cur);
7078 kfree(dattr_cur); /* kfree(NULL) is safe */
7079 doms_cur = doms_new;
7080 dattr_cur = dattr_new;
7081 ndoms_cur = ndoms_new;
7083 register_sched_domain_sysctl();
7085 mutex_unlock(&sched_domains_mutex);
7088 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
7091 * Update cpusets according to cpu_active mask. If cpusets are
7092 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7093 * around partition_sched_domains().
7095 * If we come here as part of a suspend/resume, don't touch cpusets because we
7096 * want to restore it back to its original state upon resume anyway.
7098 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
7102 case CPU_ONLINE_FROZEN:
7103 case CPU_DOWN_FAILED_FROZEN:
7106 * num_cpus_frozen tracks how many CPUs are involved in suspend
7107 * resume sequence. As long as this is not the last online
7108 * operation in the resume sequence, just build a single sched
7109 * domain, ignoring cpusets.
7112 if (likely(num_cpus_frozen)) {
7113 partition_sched_domains(1, NULL, NULL);
7118 * This is the last CPU online operation. So fall through and
7119 * restore the original sched domains by considering the
7120 * cpuset configurations.
7124 cpuset_update_active_cpus(true);
7132 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
7135 unsigned long flags;
7136 long cpu = (long)hcpu;
7142 case CPU_DOWN_PREPARE:
7143 rcu_read_lock_sched();
7144 dl_b = dl_bw_of(cpu);
7146 raw_spin_lock_irqsave(&dl_b->lock, flags);
7147 cpus = dl_bw_cpus(cpu);
7148 overflow = __dl_overflow(dl_b, cpus, 0, 0);
7149 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7151 rcu_read_unlock_sched();
7154 return notifier_from_errno(-EBUSY);
7155 cpuset_update_active_cpus(false);
7157 case CPU_DOWN_PREPARE_FROZEN:
7159 partition_sched_domains(1, NULL, NULL);
7167 void __init sched_init_smp(void)
7169 cpumask_var_t non_isolated_cpus;
7171 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7172 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7177 * There's no userspace yet to cause hotplug operations; hence all the
7178 * cpu masks are stable and all blatant races in the below code cannot
7181 mutex_lock(&sched_domains_mutex);
7182 init_sched_domains(cpu_active_mask);
7183 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
7184 if (cpumask_empty(non_isolated_cpus))
7185 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7186 mutex_unlock(&sched_domains_mutex);
7188 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
7189 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
7190 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
7194 /* Move init over to a non-isolated CPU */
7195 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7197 sched_init_granularity();
7198 free_cpumask_var(non_isolated_cpus);
7200 init_sched_rt_class();
7201 init_sched_dl_class();
7204 void __init sched_init_smp(void)
7206 sched_init_granularity();
7208 #endif /* CONFIG_SMP */
7210 int in_sched_functions(unsigned long addr)
7212 return in_lock_functions(addr) ||
7213 (addr >= (unsigned long)__sched_text_start
7214 && addr < (unsigned long)__sched_text_end);
7217 #ifdef CONFIG_CGROUP_SCHED
7219 * Default task group.
7220 * Every task in system belongs to this group at bootup.
7222 struct task_group root_task_group;
7223 LIST_HEAD(task_groups);
7225 /* Cacheline aligned slab cache for task_group */
7226 static struct kmem_cache *task_group_cache __read_mostly;
7229 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
7231 void __init sched_init(void)
7234 unsigned long alloc_size = 0, ptr;
7236 #ifdef CONFIG_FAIR_GROUP_SCHED
7237 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7239 #ifdef CONFIG_RT_GROUP_SCHED
7240 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7243 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7245 #ifdef CONFIG_FAIR_GROUP_SCHED
7246 root_task_group.se = (struct sched_entity **)ptr;
7247 ptr += nr_cpu_ids * sizeof(void **);
7249 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7250 ptr += nr_cpu_ids * sizeof(void **);
7252 #endif /* CONFIG_FAIR_GROUP_SCHED */
7253 #ifdef CONFIG_RT_GROUP_SCHED
7254 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7255 ptr += nr_cpu_ids * sizeof(void **);
7257 root_task_group.rt_rq = (struct rt_rq **)ptr;
7258 ptr += nr_cpu_ids * sizeof(void **);
7260 #endif /* CONFIG_RT_GROUP_SCHED */
7262 #ifdef CONFIG_CPUMASK_OFFSTACK
7263 for_each_possible_cpu(i) {
7264 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
7265 cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7267 #endif /* CONFIG_CPUMASK_OFFSTACK */
7269 init_rt_bandwidth(&def_rt_bandwidth,
7270 global_rt_period(), global_rt_runtime());
7271 init_dl_bandwidth(&def_dl_bandwidth,
7272 global_rt_period(), global_rt_runtime());
7275 init_defrootdomain();
7278 #ifdef CONFIG_RT_GROUP_SCHED
7279 init_rt_bandwidth(&root_task_group.rt_bandwidth,
7280 global_rt_period(), global_rt_runtime());
7281 #endif /* CONFIG_RT_GROUP_SCHED */
7283 #ifdef CONFIG_CGROUP_SCHED
7284 task_group_cache = KMEM_CACHE(task_group, 0);
7286 list_add(&root_task_group.list, &task_groups);
7287 INIT_LIST_HEAD(&root_task_group.children);
7288 INIT_LIST_HEAD(&root_task_group.siblings);
7289 autogroup_init(&init_task);
7290 #endif /* CONFIG_CGROUP_SCHED */
7292 for_each_possible_cpu(i) {
7296 raw_spin_lock_init(&rq->lock);
7298 rq->calc_load_active = 0;
7299 rq->calc_load_update = jiffies + LOAD_FREQ;
7300 init_cfs_rq(&rq->cfs);
7301 init_rt_rq(&rq->rt);
7302 init_dl_rq(&rq->dl);
7303 #ifdef CONFIG_FAIR_GROUP_SCHED
7304 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7305 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7307 * How much cpu bandwidth does root_task_group get?
7309 * In case of task-groups formed thr' the cgroup filesystem, it
7310 * gets 100% of the cpu resources in the system. This overall
7311 * system cpu resource is divided among the tasks of
7312 * root_task_group and its child task-groups in a fair manner,
7313 * based on each entity's (task or task-group's) weight
7314 * (se->load.weight).
7316 * In other words, if root_task_group has 10 tasks of weight
7317 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7318 * then A0's share of the cpu resource is:
7320 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7322 * We achieve this by letting root_task_group's tasks sit
7323 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7325 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7326 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7327 #endif /* CONFIG_FAIR_GROUP_SCHED */
7329 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7330 #ifdef CONFIG_RT_GROUP_SCHED
7331 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7334 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7335 rq->cpu_load[j] = 0;
7337 rq->last_load_update_tick = jiffies;
7342 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7343 rq->balance_callback = NULL;
7344 rq->active_balance = 0;
7345 rq->next_balance = jiffies;
7350 rq->avg_idle = 2*sysctl_sched_migration_cost;
7351 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7353 INIT_LIST_HEAD(&rq->cfs_tasks);
7355 rq_attach_root(rq, &def_root_domain);
7356 #ifdef CONFIG_NO_HZ_COMMON
7359 #ifdef CONFIG_NO_HZ_FULL
7360 rq->last_sched_tick = 0;
7364 atomic_set(&rq->nr_iowait, 0);
7367 set_load_weight(&init_task);
7369 #ifdef CONFIG_PREEMPT_NOTIFIERS
7370 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7374 * The boot idle thread does lazy MMU switching as well:
7376 atomic_inc(&init_mm.mm_count);
7377 enter_lazy_tlb(&init_mm, current);
7380 * During early bootup we pretend to be a normal task:
7382 current->sched_class = &fair_sched_class;
7385 * Make us the idle thread. Technically, schedule() should not be
7386 * called from this thread, however somewhere below it might be,
7387 * but because we are the idle thread, we just pick up running again
7388 * when this runqueue becomes "idle".
7390 init_idle(current, smp_processor_id());
7392 calc_load_update = jiffies + LOAD_FREQ;
7395 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7396 /* May be allocated at isolcpus cmdline parse time */
7397 if (cpu_isolated_map == NULL)
7398 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7399 idle_thread_set_boot_cpu();
7400 set_cpu_rq_start_time();
7402 init_sched_fair_class();
7404 scheduler_running = 1;
7407 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7408 static inline int preempt_count_equals(int preempt_offset)
7410 int nested = preempt_count() + rcu_preempt_depth();
7412 return (nested == preempt_offset);
7415 void __might_sleep(const char *file, int line, int preempt_offset)
7418 * Blocking primitives will set (and therefore destroy) current->state,
7419 * since we will exit with TASK_RUNNING make sure we enter with it,
7420 * otherwise we will destroy state.
7422 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
7423 "do not call blocking ops when !TASK_RUNNING; "
7424 "state=%lx set at [<%p>] %pS\n",
7426 (void *)current->task_state_change,
7427 (void *)current->task_state_change);
7429 ___might_sleep(file, line, preempt_offset);
7431 EXPORT_SYMBOL(__might_sleep);
7433 void ___might_sleep(const char *file, int line, int preempt_offset)
7435 static unsigned long prev_jiffy; /* ratelimiting */
7437 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7438 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7439 !is_idle_task(current)) ||
7440 system_state != SYSTEM_RUNNING || oops_in_progress)
7442 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7444 prev_jiffy = jiffies;
7447 "BUG: sleeping function called from invalid context at %s:%d\n",
7450 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7451 in_atomic(), irqs_disabled(),
7452 current->pid, current->comm);
7454 if (task_stack_end_corrupted(current))
7455 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
7457 debug_show_held_locks(current);
7458 if (irqs_disabled())
7459 print_irqtrace_events(current);
7460 #ifdef CONFIG_DEBUG_PREEMPT
7461 if (!preempt_count_equals(preempt_offset)) {
7462 pr_err("Preemption disabled at:");
7463 print_ip_sym(current->preempt_disable_ip);
7469 EXPORT_SYMBOL(___might_sleep);
7472 #ifdef CONFIG_MAGIC_SYSRQ
7473 void normalize_rt_tasks(void)
7475 struct task_struct *g, *p;
7476 struct sched_attr attr = {
7477 .sched_policy = SCHED_NORMAL,
7480 read_lock(&tasklist_lock);
7481 for_each_process_thread(g, p) {
7483 * Only normalize user tasks:
7485 if (p->flags & PF_KTHREAD)
7488 p->se.exec_start = 0;
7489 #ifdef CONFIG_SCHEDSTATS
7490 p->se.statistics.wait_start = 0;
7491 p->se.statistics.sleep_start = 0;
7492 p->se.statistics.block_start = 0;
7495 if (!dl_task(p) && !rt_task(p)) {
7497 * Renice negative nice level userspace
7500 if (task_nice(p) < 0)
7501 set_user_nice(p, 0);
7505 __sched_setscheduler(p, &attr, false, false);
7507 read_unlock(&tasklist_lock);
7510 #endif /* CONFIG_MAGIC_SYSRQ */
7512 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7514 * These functions are only useful for the IA64 MCA handling, or kdb.
7516 * They can only be called when the whole system has been
7517 * stopped - every CPU needs to be quiescent, and no scheduling
7518 * activity can take place. Using them for anything else would
7519 * be a serious bug, and as a result, they aren't even visible
7520 * under any other configuration.
7524 * curr_task - return the current task for a given cpu.
7525 * @cpu: the processor in question.
7527 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7529 * Return: The current task for @cpu.
7531 struct task_struct *curr_task(int cpu)
7533 return cpu_curr(cpu);
7536 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7540 * set_curr_task - set the current task for a given cpu.
7541 * @cpu: the processor in question.
7542 * @p: the task pointer to set.
7544 * Description: This function must only be used when non-maskable interrupts
7545 * are serviced on a separate stack. It allows the architecture to switch the
7546 * notion of the current task on a cpu in a non-blocking manner. This function
7547 * must be called with all CPU's synchronized, and interrupts disabled, the
7548 * and caller must save the original value of the current task (see
7549 * curr_task() above) and restore that value before reenabling interrupts and
7550 * re-starting the system.
7552 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7554 void set_curr_task(int cpu, struct task_struct *p)
7561 #ifdef CONFIG_CGROUP_SCHED
7562 /* task_group_lock serializes the addition/removal of task groups */
7563 static DEFINE_SPINLOCK(task_group_lock);
7565 static void free_sched_group(struct task_group *tg)
7567 free_fair_sched_group(tg);
7568 free_rt_sched_group(tg);
7570 kmem_cache_free(task_group_cache, tg);
7573 /* allocate runqueue etc for a new task group */
7574 struct task_group *sched_create_group(struct task_group *parent)
7576 struct task_group *tg;
7578 tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
7580 return ERR_PTR(-ENOMEM);
7582 if (!alloc_fair_sched_group(tg, parent))
7585 if (!alloc_rt_sched_group(tg, parent))
7591 free_sched_group(tg);
7592 return ERR_PTR(-ENOMEM);
7595 void sched_online_group(struct task_group *tg, struct task_group *parent)
7597 unsigned long flags;
7599 spin_lock_irqsave(&task_group_lock, flags);
7600 list_add_rcu(&tg->list, &task_groups);
7602 WARN_ON(!parent); /* root should already exist */
7604 tg->parent = parent;
7605 INIT_LIST_HEAD(&tg->children);
7606 list_add_rcu(&tg->siblings, &parent->children);
7607 spin_unlock_irqrestore(&task_group_lock, flags);
7610 /* rcu callback to free various structures associated with a task group */
7611 static void free_sched_group_rcu(struct rcu_head *rhp)
7613 /* now it should be safe to free those cfs_rqs */
7614 free_sched_group(container_of(rhp, struct task_group, rcu));
7617 /* Destroy runqueue etc associated with a task group */
7618 void sched_destroy_group(struct task_group *tg)
7620 /* wait for possible concurrent references to cfs_rqs complete */
7621 call_rcu(&tg->rcu, free_sched_group_rcu);
7624 void sched_offline_group(struct task_group *tg)
7626 unsigned long flags;
7628 /* end participation in shares distribution */
7629 unregister_fair_sched_group(tg);
7631 spin_lock_irqsave(&task_group_lock, flags);
7632 list_del_rcu(&tg->list);
7633 list_del_rcu(&tg->siblings);
7634 spin_unlock_irqrestore(&task_group_lock, flags);
7637 /* change task's runqueue when it moves between groups.
7638 * The caller of this function should have put the task in its new group
7639 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7640 * reflect its new group.
7642 void sched_move_task(struct task_struct *tsk)
7644 struct task_group *tg;
7645 int queued, running;
7646 unsigned long flags;
7649 rq = task_rq_lock(tsk, &flags);
7651 running = task_current(rq, tsk);
7652 queued = task_on_rq_queued(tsk);
7655 dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
7656 if (unlikely(running))
7657 put_prev_task(rq, tsk);
7660 * All callers are synchronized by task_rq_lock(); we do not use RCU
7661 * which is pointless here. Thus, we pass "true" to task_css_check()
7662 * to prevent lockdep warnings.
7664 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
7665 struct task_group, css);
7666 tg = autogroup_task_group(tsk, tg);
7667 tsk->sched_task_group = tg;
7669 #ifdef CONFIG_FAIR_GROUP_SCHED
7670 if (tsk->sched_class->task_move_group)
7671 tsk->sched_class->task_move_group(tsk);
7674 set_task_rq(tsk, task_cpu(tsk));
7676 if (unlikely(running))
7677 tsk->sched_class->set_curr_task(rq);
7679 enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
7681 task_rq_unlock(rq, tsk, &flags);
7683 #endif /* CONFIG_CGROUP_SCHED */
7685 #ifdef CONFIG_RT_GROUP_SCHED
7687 * Ensure that the real time constraints are schedulable.
7689 static DEFINE_MUTEX(rt_constraints_mutex);
7691 /* Must be called with tasklist_lock held */
7692 static inline int tg_has_rt_tasks(struct task_group *tg)
7694 struct task_struct *g, *p;
7697 * Autogroups do not have RT tasks; see autogroup_create().
7699 if (task_group_is_autogroup(tg))
7702 for_each_process_thread(g, p) {
7703 if (rt_task(p) && task_group(p) == tg)
7710 struct rt_schedulable_data {
7711 struct task_group *tg;
7716 static int tg_rt_schedulable(struct task_group *tg, void *data)
7718 struct rt_schedulable_data *d = data;
7719 struct task_group *child;
7720 unsigned long total, sum = 0;
7721 u64 period, runtime;
7723 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7724 runtime = tg->rt_bandwidth.rt_runtime;
7727 period = d->rt_period;
7728 runtime = d->rt_runtime;
7732 * Cannot have more runtime than the period.
7734 if (runtime > period && runtime != RUNTIME_INF)
7738 * Ensure we don't starve existing RT tasks.
7740 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7743 total = to_ratio(period, runtime);
7746 * Nobody can have more than the global setting allows.
7748 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7752 * The sum of our children's runtime should not exceed our own.
7754 list_for_each_entry_rcu(child, &tg->children, siblings) {
7755 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7756 runtime = child->rt_bandwidth.rt_runtime;
7758 if (child == d->tg) {
7759 period = d->rt_period;
7760 runtime = d->rt_runtime;
7763 sum += to_ratio(period, runtime);
7772 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7776 struct rt_schedulable_data data = {
7778 .rt_period = period,
7779 .rt_runtime = runtime,
7783 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7789 static int tg_set_rt_bandwidth(struct task_group *tg,
7790 u64 rt_period, u64 rt_runtime)
7795 * Disallowing the root group RT runtime is BAD, it would disallow the
7796 * kernel creating (and or operating) RT threads.
7798 if (tg == &root_task_group && rt_runtime == 0)
7801 /* No period doesn't make any sense. */
7805 mutex_lock(&rt_constraints_mutex);
7806 read_lock(&tasklist_lock);
7807 err = __rt_schedulable(tg, rt_period, rt_runtime);
7811 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7812 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7813 tg->rt_bandwidth.rt_runtime = rt_runtime;
7815 for_each_possible_cpu(i) {
7816 struct rt_rq *rt_rq = tg->rt_rq[i];
7818 raw_spin_lock(&rt_rq->rt_runtime_lock);
7819 rt_rq->rt_runtime = rt_runtime;
7820 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7822 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7824 read_unlock(&tasklist_lock);
7825 mutex_unlock(&rt_constraints_mutex);
7830 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7832 u64 rt_runtime, rt_period;
7834 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7835 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7836 if (rt_runtime_us < 0)
7837 rt_runtime = RUNTIME_INF;
7839 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7842 static long sched_group_rt_runtime(struct task_group *tg)
7846 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7849 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7850 do_div(rt_runtime_us, NSEC_PER_USEC);
7851 return rt_runtime_us;
7854 static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
7856 u64 rt_runtime, rt_period;
7858 rt_period = rt_period_us * NSEC_PER_USEC;
7859 rt_runtime = tg->rt_bandwidth.rt_runtime;
7861 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7864 static long sched_group_rt_period(struct task_group *tg)
7868 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7869 do_div(rt_period_us, NSEC_PER_USEC);
7870 return rt_period_us;
7872 #endif /* CONFIG_RT_GROUP_SCHED */
7874 #ifdef CONFIG_RT_GROUP_SCHED
7875 static int sched_rt_global_constraints(void)
7879 mutex_lock(&rt_constraints_mutex);
7880 read_lock(&tasklist_lock);
7881 ret = __rt_schedulable(NULL, 0, 0);
7882 read_unlock(&tasklist_lock);
7883 mutex_unlock(&rt_constraints_mutex);
7888 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7890 /* Don't accept realtime tasks when there is no way for them to run */
7891 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7897 #else /* !CONFIG_RT_GROUP_SCHED */
7898 static int sched_rt_global_constraints(void)
7900 unsigned long flags;
7903 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7904 for_each_possible_cpu(i) {
7905 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7907 raw_spin_lock(&rt_rq->rt_runtime_lock);
7908 rt_rq->rt_runtime = global_rt_runtime();
7909 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7911 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7915 #endif /* CONFIG_RT_GROUP_SCHED */
7917 static int sched_dl_global_validate(void)
7919 u64 runtime = global_rt_runtime();
7920 u64 period = global_rt_period();
7921 u64 new_bw = to_ratio(period, runtime);
7924 unsigned long flags;
7927 * Here we want to check the bandwidth not being set to some
7928 * value smaller than the currently allocated bandwidth in
7929 * any of the root_domains.
7931 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7932 * cycling on root_domains... Discussion on different/better
7933 * solutions is welcome!
7935 for_each_possible_cpu(cpu) {
7936 rcu_read_lock_sched();
7937 dl_b = dl_bw_of(cpu);
7939 raw_spin_lock_irqsave(&dl_b->lock, flags);
7940 if (new_bw < dl_b->total_bw)
7942 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7944 rcu_read_unlock_sched();
7953 static void sched_dl_do_global(void)
7958 unsigned long flags;
7960 def_dl_bandwidth.dl_period = global_rt_period();
7961 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7963 if (global_rt_runtime() != RUNTIME_INF)
7964 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7967 * FIXME: As above...
7969 for_each_possible_cpu(cpu) {
7970 rcu_read_lock_sched();
7971 dl_b = dl_bw_of(cpu);
7973 raw_spin_lock_irqsave(&dl_b->lock, flags);
7975 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7977 rcu_read_unlock_sched();
7981 static int sched_rt_global_validate(void)
7983 if (sysctl_sched_rt_period <= 0)
7986 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7987 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7993 static void sched_rt_do_global(void)
7995 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7996 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7999 int sched_rt_handler(struct ctl_table *table, int write,
8000 void __user *buffer, size_t *lenp,
8003 int old_period, old_runtime;
8004 static DEFINE_MUTEX(mutex);
8008 old_period = sysctl_sched_rt_period;
8009 old_runtime = sysctl_sched_rt_runtime;
8011 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8013 if (!ret && write) {
8014 ret = sched_rt_global_validate();
8018 ret = sched_dl_global_validate();
8022 ret = sched_rt_global_constraints();
8026 sched_rt_do_global();
8027 sched_dl_do_global();
8031 sysctl_sched_rt_period = old_period;
8032 sysctl_sched_rt_runtime = old_runtime;
8034 mutex_unlock(&mutex);
8039 int sched_rr_handler(struct ctl_table *table, int write,
8040 void __user *buffer, size_t *lenp,
8044 static DEFINE_MUTEX(mutex);
8047 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8048 /* make sure that internally we keep jiffies */
8049 /* also, writing zero resets timeslice to default */
8050 if (!ret && write) {
8051 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
8052 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8054 mutex_unlock(&mutex);
8058 #ifdef CONFIG_CGROUP_SCHED
8060 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8062 return css ? container_of(css, struct task_group, css) : NULL;
8065 static struct cgroup_subsys_state *
8066 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8068 struct task_group *parent = css_tg(parent_css);
8069 struct task_group *tg;
8072 /* This is early initialization for the top cgroup */
8073 return &root_task_group.css;
8076 tg = sched_create_group(parent);
8078 return ERR_PTR(-ENOMEM);
8083 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
8085 struct task_group *tg = css_tg(css);
8086 struct task_group *parent = css_tg(css->parent);
8089 sched_online_group(tg, parent);
8093 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8095 struct task_group *tg = css_tg(css);
8097 sched_destroy_group(tg);
8100 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
8102 struct task_group *tg = css_tg(css);
8104 sched_offline_group(tg);
8107 static void cpu_cgroup_fork(struct task_struct *task)
8109 sched_move_task(task);
8112 static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
8114 struct task_struct *task;
8115 struct cgroup_subsys_state *css;
8117 cgroup_taskset_for_each(task, css, tset) {
8118 #ifdef CONFIG_RT_GROUP_SCHED
8119 if (!sched_rt_can_attach(css_tg(css), task))
8122 /* We don't support RT-tasks being in separate groups */
8123 if (task->sched_class != &fair_sched_class)
8130 static void cpu_cgroup_attach(struct cgroup_taskset *tset)
8132 struct task_struct *task;
8133 struct cgroup_subsys_state *css;
8135 cgroup_taskset_for_each(task, css, tset)
8136 sched_move_task(task);
8139 #ifdef CONFIG_FAIR_GROUP_SCHED
8140 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
8141 struct cftype *cftype, u64 shareval)
8143 return sched_group_set_shares(css_tg(css), scale_load(shareval));
8146 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
8149 struct task_group *tg = css_tg(css);
8151 return (u64) scale_load_down(tg->shares);
8154 #ifdef CONFIG_CFS_BANDWIDTH
8155 static DEFINE_MUTEX(cfs_constraints_mutex);
8157 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
8158 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
8160 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
8162 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
8164 int i, ret = 0, runtime_enabled, runtime_was_enabled;
8165 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8167 if (tg == &root_task_group)
8171 * Ensure we have at some amount of bandwidth every period. This is
8172 * to prevent reaching a state of large arrears when throttled via
8173 * entity_tick() resulting in prolonged exit starvation.
8175 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
8179 * Likewise, bound things on the otherside by preventing insane quota
8180 * periods. This also allows us to normalize in computing quota
8183 if (period > max_cfs_quota_period)
8187 * Prevent race between setting of cfs_rq->runtime_enabled and
8188 * unthrottle_offline_cfs_rqs().
8191 mutex_lock(&cfs_constraints_mutex);
8192 ret = __cfs_schedulable(tg, period, quota);
8196 runtime_enabled = quota != RUNTIME_INF;
8197 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8199 * If we need to toggle cfs_bandwidth_used, off->on must occur
8200 * before making related changes, and on->off must occur afterwards
8202 if (runtime_enabled && !runtime_was_enabled)
8203 cfs_bandwidth_usage_inc();
8204 raw_spin_lock_irq(&cfs_b->lock);
8205 cfs_b->period = ns_to_ktime(period);
8206 cfs_b->quota = quota;
8208 __refill_cfs_bandwidth_runtime(cfs_b);
8209 /* restart the period timer (if active) to handle new period expiry */
8210 if (runtime_enabled)
8211 start_cfs_bandwidth(cfs_b);
8212 raw_spin_unlock_irq(&cfs_b->lock);
8214 for_each_online_cpu(i) {
8215 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8216 struct rq *rq = cfs_rq->rq;
8218 raw_spin_lock_irq(&rq->lock);
8219 cfs_rq->runtime_enabled = runtime_enabled;
8220 cfs_rq->runtime_remaining = 0;
8222 if (cfs_rq->throttled)
8223 unthrottle_cfs_rq(cfs_rq);
8224 raw_spin_unlock_irq(&rq->lock);
8226 if (runtime_was_enabled && !runtime_enabled)
8227 cfs_bandwidth_usage_dec();
8229 mutex_unlock(&cfs_constraints_mutex);
8235 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
8239 period = ktime_to_ns(tg->cfs_bandwidth.period);
8240 if (cfs_quota_us < 0)
8241 quota = RUNTIME_INF;
8243 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
8245 return tg_set_cfs_bandwidth(tg, period, quota);
8248 long tg_get_cfs_quota(struct task_group *tg)
8252 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8255 quota_us = tg->cfs_bandwidth.quota;
8256 do_div(quota_us, NSEC_PER_USEC);
8261 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
8265 period = (u64)cfs_period_us * NSEC_PER_USEC;
8266 quota = tg->cfs_bandwidth.quota;
8268 return tg_set_cfs_bandwidth(tg, period, quota);
8271 long tg_get_cfs_period(struct task_group *tg)
8275 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8276 do_div(cfs_period_us, NSEC_PER_USEC);
8278 return cfs_period_us;
8281 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
8284 return tg_get_cfs_quota(css_tg(css));
8287 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
8288 struct cftype *cftype, s64 cfs_quota_us)
8290 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8293 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
8296 return tg_get_cfs_period(css_tg(css));
8299 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
8300 struct cftype *cftype, u64 cfs_period_us)
8302 return tg_set_cfs_period(css_tg(css), cfs_period_us);
8305 struct cfs_schedulable_data {
8306 struct task_group *tg;
8311 * normalize group quota/period to be quota/max_period
8312 * note: units are usecs
8314 static u64 normalize_cfs_quota(struct task_group *tg,
8315 struct cfs_schedulable_data *d)
8323 period = tg_get_cfs_period(tg);
8324 quota = tg_get_cfs_quota(tg);
8327 /* note: these should typically be equivalent */
8328 if (quota == RUNTIME_INF || quota == -1)
8331 return to_ratio(period, quota);
8334 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8336 struct cfs_schedulable_data *d = data;
8337 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8338 s64 quota = 0, parent_quota = -1;
8341 quota = RUNTIME_INF;
8343 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8345 quota = normalize_cfs_quota(tg, d);
8346 parent_quota = parent_b->hierarchical_quota;
8349 * ensure max(child_quota) <= parent_quota, inherit when no
8352 if (quota == RUNTIME_INF)
8353 quota = parent_quota;
8354 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8357 cfs_b->hierarchical_quota = quota;
8362 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8365 struct cfs_schedulable_data data = {
8371 if (quota != RUNTIME_INF) {
8372 do_div(data.period, NSEC_PER_USEC);
8373 do_div(data.quota, NSEC_PER_USEC);
8377 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8383 static int cpu_stats_show(struct seq_file *sf, void *v)
8385 struct task_group *tg = css_tg(seq_css(sf));
8386 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8388 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8389 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8390 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8394 #endif /* CONFIG_CFS_BANDWIDTH */
8395 #endif /* CONFIG_FAIR_GROUP_SCHED */
8397 #ifdef CONFIG_RT_GROUP_SCHED
8398 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8399 struct cftype *cft, s64 val)
8401 return sched_group_set_rt_runtime(css_tg(css), val);
8404 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8407 return sched_group_rt_runtime(css_tg(css));
8410 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8411 struct cftype *cftype, u64 rt_period_us)
8413 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8416 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8419 return sched_group_rt_period(css_tg(css));
8421 #endif /* CONFIG_RT_GROUP_SCHED */
8423 static struct cftype cpu_files[] = {
8424 #ifdef CONFIG_FAIR_GROUP_SCHED
8427 .read_u64 = cpu_shares_read_u64,
8428 .write_u64 = cpu_shares_write_u64,
8431 #ifdef CONFIG_CFS_BANDWIDTH
8433 .name = "cfs_quota_us",
8434 .read_s64 = cpu_cfs_quota_read_s64,
8435 .write_s64 = cpu_cfs_quota_write_s64,
8438 .name = "cfs_period_us",
8439 .read_u64 = cpu_cfs_period_read_u64,
8440 .write_u64 = cpu_cfs_period_write_u64,
8444 .seq_show = cpu_stats_show,
8447 #ifdef CONFIG_RT_GROUP_SCHED
8449 .name = "rt_runtime_us",
8450 .read_s64 = cpu_rt_runtime_read,
8451 .write_s64 = cpu_rt_runtime_write,
8454 .name = "rt_period_us",
8455 .read_u64 = cpu_rt_period_read_uint,
8456 .write_u64 = cpu_rt_period_write_uint,
8462 struct cgroup_subsys cpu_cgrp_subsys = {
8463 .css_alloc = cpu_cgroup_css_alloc,
8464 .css_free = cpu_cgroup_css_free,
8465 .css_online = cpu_cgroup_css_online,
8466 .css_offline = cpu_cgroup_css_offline,
8467 .fork = cpu_cgroup_fork,
8468 .can_attach = cpu_cgroup_can_attach,
8469 .attach = cpu_cgroup_attach,
8470 .legacy_cftypes = cpu_files,
8474 #endif /* CONFIG_CGROUP_SCHED */
8476 void dump_cpu_task(int cpu)
8478 pr_info("Task dump for CPU %d:\n", cpu);
8479 sched_show_task(cpu_curr(cpu));
8483 * Nice levels are multiplicative, with a gentle 10% change for every
8484 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
8485 * nice 1, it will get ~10% less CPU time than another CPU-bound task
8486 * that remained on nice 0.
8488 * The "10% effect" is relative and cumulative: from _any_ nice level,
8489 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
8490 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
8491 * If a task goes up by ~10% and another task goes down by ~10% then
8492 * the relative distance between them is ~25%.)
8494 const int sched_prio_to_weight[40] = {
8495 /* -20 */ 88761, 71755, 56483, 46273, 36291,
8496 /* -15 */ 29154, 23254, 18705, 14949, 11916,
8497 /* -10 */ 9548, 7620, 6100, 4904, 3906,
8498 /* -5 */ 3121, 2501, 1991, 1586, 1277,
8499 /* 0 */ 1024, 820, 655, 526, 423,
8500 /* 5 */ 335, 272, 215, 172, 137,
8501 /* 10 */ 110, 87, 70, 56, 45,
8502 /* 15 */ 36, 29, 23, 18, 15,
8506 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
8508 * In cases where the weight does not change often, we can use the
8509 * precalculated inverse to speed up arithmetics by turning divisions
8510 * into multiplications:
8512 const u32 sched_prio_to_wmult[40] = {
8513 /* -20 */ 48388, 59856, 76040, 92818, 118348,
8514 /* -15 */ 147320, 184698, 229616, 287308, 360437,
8515 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
8516 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
8517 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
8518 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
8519 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
8520 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,