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
29 #include <linux/kasan.h>
31 #include <linux/module.h>
32 #include <linux/nmi.h>
33 #include <linux/init.h>
34 #include <linux/uaccess.h>
35 #include <linux/highmem.h>
36 #include <asm/mmu_context.h>
37 #include <linux/interrupt.h>
38 #include <linux/capability.h>
39 #include <linux/completion.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/debug_locks.h>
42 #include <linux/perf_event.h>
43 #include <linux/security.h>
44 #include <linux/notifier.h>
45 #include <linux/profile.h>
46 #include <linux/freezer.h>
47 #include <linux/vmalloc.h>
48 #include <linux/blkdev.h>
49 #include <linux/delay.h>
50 #include <linux/pid_namespace.h>
51 #include <linux/smp.h>
52 #include <linux/threads.h>
53 #include <linux/timer.h>
54 #include <linux/rcupdate.h>
55 #include <linux/cpu.h>
56 #include <linux/cpuset.h>
57 #include <linux/percpu.h>
58 #include <linux/proc_fs.h>
59 #include <linux/seq_file.h>
60 #include <linux/sysctl.h>
61 #include <linux/syscalls.h>
62 #include <linux/times.h>
63 #include <linux/tsacct_kern.h>
64 #include <linux/kprobes.h>
65 #include <linux/delayacct.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.h>
70 #include <linux/ctype.h>
71 #include <linux/ftrace.h>
72 #include <linux/slab.h>
73 #include <linux/init_task.h>
74 #include <linux/context_tracking.h>
75 #include <linux/compiler.h>
77 #include <asm/switch_to.h>
79 #include <asm/irq_regs.h>
80 #include <asm/mutex.h>
81 #ifdef CONFIG_PARAVIRT
82 #include <asm/paravirt.h>
86 #include "../workqueue_internal.h"
87 #include "../smpboot.h"
89 #define CREATE_TRACE_POINTS
90 #include <trace/events/sched.h>
92 DEFINE_MUTEX(sched_domains_mutex);
93 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
95 static void update_rq_clock_task(struct rq *rq, s64 delta);
97 void update_rq_clock(struct rq *rq)
101 lockdep_assert_held(&rq->lock);
103 if (rq->clock_skip_update & RQCF_ACT_SKIP)
106 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
110 update_rq_clock_task(rq, delta);
114 * Debugging: various feature bits
117 #define SCHED_FEAT(name, enabled) \
118 (1UL << __SCHED_FEAT_##name) * enabled |
120 const_debug unsigned int sysctl_sched_features =
121 #include "features.h"
127 * Number of tasks to iterate in a single balance run.
128 * Limited because this is done with IRQs disabled.
130 const_debug unsigned int sysctl_sched_nr_migrate = 32;
133 * period over which we average the RT time consumption, measured
138 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
141 * period over which we measure -rt task cpu usage in us.
144 unsigned int sysctl_sched_rt_period = 1000000;
146 __read_mostly int scheduler_running;
149 * part of the period that we allow rt tasks to run in us.
152 int sysctl_sched_rt_runtime = 950000;
154 /* cpus with isolated domains */
155 cpumask_var_t cpu_isolated_map;
158 * this_rq_lock - lock this runqueue and disable interrupts.
160 static struct rq *this_rq_lock(void)
167 raw_spin_lock(&rq->lock);
172 #ifdef CONFIG_SCHED_HRTICK
174 * Use HR-timers to deliver accurate preemption points.
177 static void hrtick_clear(struct rq *rq)
179 if (hrtimer_active(&rq->hrtick_timer))
180 hrtimer_cancel(&rq->hrtick_timer);
184 * High-resolution timer tick.
185 * Runs from hardirq context with interrupts disabled.
187 static enum hrtimer_restart hrtick(struct hrtimer *timer)
189 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
191 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
193 raw_spin_lock(&rq->lock);
195 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
196 raw_spin_unlock(&rq->lock);
198 return HRTIMER_NORESTART;
203 static void __hrtick_restart(struct rq *rq)
205 struct hrtimer *timer = &rq->hrtick_timer;
207 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
211 * called from hardirq (IPI) context
213 static void __hrtick_start(void *arg)
217 raw_spin_lock(&rq->lock);
218 __hrtick_restart(rq);
219 rq->hrtick_csd_pending = 0;
220 raw_spin_unlock(&rq->lock);
224 * Called to set the hrtick timer state.
226 * called with rq->lock held and irqs disabled
228 void hrtick_start(struct rq *rq, u64 delay)
230 struct hrtimer *timer = &rq->hrtick_timer;
235 * Don't schedule slices shorter than 10000ns, that just
236 * doesn't make sense and can cause timer DoS.
238 delta = max_t(s64, delay, 10000LL);
239 time = ktime_add_ns(timer->base->get_time(), delta);
241 hrtimer_set_expires(timer, time);
243 if (rq == this_rq()) {
244 __hrtick_restart(rq);
245 } else if (!rq->hrtick_csd_pending) {
246 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
247 rq->hrtick_csd_pending = 1;
252 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
254 int cpu = (int)(long)hcpu;
257 case CPU_UP_CANCELED:
258 case CPU_UP_CANCELED_FROZEN:
259 case CPU_DOWN_PREPARE:
260 case CPU_DOWN_PREPARE_FROZEN:
262 case CPU_DEAD_FROZEN:
263 hrtick_clear(cpu_rq(cpu));
270 static __init void init_hrtick(void)
272 hotcpu_notifier(hotplug_hrtick, 0);
276 * Called to set the hrtick timer state.
278 * called with rq->lock held and irqs disabled
280 void hrtick_start(struct rq *rq, u64 delay)
283 * Don't schedule slices shorter than 10000ns, that just
284 * doesn't make sense. Rely on vruntime for fairness.
286 delay = max_t(u64, delay, 10000LL);
287 hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
288 HRTIMER_MODE_REL_PINNED);
291 static inline void init_hrtick(void)
294 #endif /* CONFIG_SMP */
296 static void init_rq_hrtick(struct rq *rq)
299 rq->hrtick_csd_pending = 0;
301 rq->hrtick_csd.flags = 0;
302 rq->hrtick_csd.func = __hrtick_start;
303 rq->hrtick_csd.info = rq;
306 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
307 rq->hrtick_timer.function = hrtick;
309 #else /* CONFIG_SCHED_HRTICK */
310 static inline void hrtick_clear(struct rq *rq)
314 static inline void init_rq_hrtick(struct rq *rq)
318 static inline void init_hrtick(void)
321 #endif /* CONFIG_SCHED_HRTICK */
324 * cmpxchg based fetch_or, macro so it works for different integer types
326 #define fetch_or(ptr, val) \
327 ({ typeof(*(ptr)) __old, __val = *(ptr); \
329 __old = cmpxchg((ptr), __val, __val | (val)); \
330 if (__old == __val) \
337 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
339 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
340 * this avoids any races wrt polling state changes and thereby avoids
343 static bool set_nr_and_not_polling(struct task_struct *p)
345 struct thread_info *ti = task_thread_info(p);
346 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
350 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
352 * If this returns true, then the idle task promises to call
353 * sched_ttwu_pending() and reschedule soon.
355 static bool set_nr_if_polling(struct task_struct *p)
357 struct thread_info *ti = task_thread_info(p);
358 typeof(ti->flags) old, val = READ_ONCE(ti->flags);
361 if (!(val & _TIF_POLLING_NRFLAG))
363 if (val & _TIF_NEED_RESCHED)
365 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
374 static bool set_nr_and_not_polling(struct task_struct *p)
376 set_tsk_need_resched(p);
381 static bool set_nr_if_polling(struct task_struct *p)
388 void wake_q_add(struct wake_q_head *head, struct task_struct *task)
390 struct wake_q_node *node = &task->wake_q;
393 * Atomically grab the task, if ->wake_q is !nil already it means
394 * its already queued (either by us or someone else) and will get the
395 * wakeup due to that.
397 * This cmpxchg() implies a full barrier, which pairs with the write
398 * barrier implied by the wakeup in wake_up_list().
400 if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
403 get_task_struct(task);
406 * The head is context local, there can be no concurrency.
409 head->lastp = &node->next;
412 void wake_up_q(struct wake_q_head *head)
414 struct wake_q_node *node = head->first;
416 while (node != WAKE_Q_TAIL) {
417 struct task_struct *task;
419 task = container_of(node, struct task_struct, wake_q);
421 /* task can safely be re-inserted now */
423 task->wake_q.next = NULL;
426 * wake_up_process() implies a wmb() to pair with the queueing
427 * in wake_q_add() so as not to miss wakeups.
429 wake_up_process(task);
430 put_task_struct(task);
435 * resched_curr - mark rq's current task 'to be rescheduled now'.
437 * On UP this means the setting of the need_resched flag, on SMP it
438 * might also involve a cross-CPU call to trigger the scheduler on
441 void resched_curr(struct rq *rq)
443 struct task_struct *curr = rq->curr;
446 lockdep_assert_held(&rq->lock);
448 if (test_tsk_need_resched(curr))
453 if (cpu == smp_processor_id()) {
454 set_tsk_need_resched(curr);
455 set_preempt_need_resched();
459 if (set_nr_and_not_polling(curr))
460 smp_send_reschedule(cpu);
462 trace_sched_wake_idle_without_ipi(cpu);
465 void resched_cpu(int cpu)
467 struct rq *rq = cpu_rq(cpu);
470 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
473 raw_spin_unlock_irqrestore(&rq->lock, flags);
477 #ifdef CONFIG_NO_HZ_COMMON
479 * In the semi idle case, use the nearest busy cpu for migrating timers
480 * from an idle cpu. This is good for power-savings.
482 * We don't do similar optimization for completely idle system, as
483 * selecting an idle cpu will add more delays to the timers than intended
484 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
486 int get_nohz_timer_target(void)
488 int i, cpu = smp_processor_id();
489 struct sched_domain *sd;
491 if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
495 for_each_domain(cpu, sd) {
496 for_each_cpu(i, sched_domain_span(sd)) {
497 if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
504 if (!is_housekeeping_cpu(cpu))
505 cpu = housekeeping_any_cpu();
511 * When add_timer_on() enqueues a timer into the timer wheel of an
512 * idle CPU then this timer might expire before the next timer event
513 * which is scheduled to wake up that CPU. In case of a completely
514 * idle system the next event might even be infinite time into the
515 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
516 * leaves the inner idle loop so the newly added timer is taken into
517 * account when the CPU goes back to idle and evaluates the timer
518 * wheel for the next timer event.
520 static void wake_up_idle_cpu(int cpu)
522 struct rq *rq = cpu_rq(cpu);
524 if (cpu == smp_processor_id())
527 if (set_nr_and_not_polling(rq->idle))
528 smp_send_reschedule(cpu);
530 trace_sched_wake_idle_without_ipi(cpu);
533 static bool wake_up_full_nohz_cpu(int cpu)
536 * We just need the target to call irq_exit() and re-evaluate
537 * the next tick. The nohz full kick at least implies that.
538 * If needed we can still optimize that later with an
541 if (tick_nohz_full_cpu(cpu)) {
542 if (cpu != smp_processor_id() ||
543 tick_nohz_tick_stopped())
544 tick_nohz_full_kick_cpu(cpu);
551 void wake_up_nohz_cpu(int cpu)
553 if (!wake_up_full_nohz_cpu(cpu))
554 wake_up_idle_cpu(cpu);
557 static inline bool got_nohz_idle_kick(void)
559 int cpu = smp_processor_id();
561 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
564 if (idle_cpu(cpu) && !need_resched())
568 * We can't run Idle Load Balance on this CPU for this time so we
569 * cancel it and clear NOHZ_BALANCE_KICK
571 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
575 #else /* CONFIG_NO_HZ_COMMON */
577 static inline bool got_nohz_idle_kick(void)
582 #endif /* CONFIG_NO_HZ_COMMON */
584 #ifdef CONFIG_NO_HZ_FULL
585 bool sched_can_stop_tick(void)
588 * FIFO realtime policy runs the highest priority task. Other runnable
589 * tasks are of a lower priority. The scheduler tick does nothing.
591 if (current->policy == SCHED_FIFO)
595 * Round-robin realtime tasks time slice with other tasks at the same
596 * realtime priority. Is this task the only one at this priority?
598 if (current->policy == SCHED_RR) {
599 struct sched_rt_entity *rt_se = ¤t->rt;
601 return list_is_singular(&rt_se->run_list);
605 * More than one running task need preemption.
606 * nr_running update is assumed to be visible
607 * after IPI is sent from wakers.
609 if (this_rq()->nr_running > 1)
614 #endif /* CONFIG_NO_HZ_FULL */
616 void sched_avg_update(struct rq *rq)
618 s64 period = sched_avg_period();
620 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
622 * Inline assembly required to prevent the compiler
623 * optimising this loop into a divmod call.
624 * See __iter_div_u64_rem() for another example of this.
626 asm("" : "+rm" (rq->age_stamp));
627 rq->age_stamp += period;
632 #endif /* CONFIG_SMP */
634 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
635 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
637 * Iterate task_group tree rooted at *from, calling @down when first entering a
638 * node and @up when leaving it for the final time.
640 * Caller must hold rcu_lock or sufficient equivalent.
642 int walk_tg_tree_from(struct task_group *from,
643 tg_visitor down, tg_visitor up, void *data)
645 struct task_group *parent, *child;
651 ret = (*down)(parent, data);
654 list_for_each_entry_rcu(child, &parent->children, siblings) {
661 ret = (*up)(parent, data);
662 if (ret || parent == from)
666 parent = parent->parent;
673 int tg_nop(struct task_group *tg, void *data)
679 static void set_load_weight(struct task_struct *p)
681 int prio = p->static_prio - MAX_RT_PRIO;
682 struct load_weight *load = &p->se.load;
685 * SCHED_IDLE tasks get minimal weight:
687 if (idle_policy(p->policy)) {
688 load->weight = scale_load(WEIGHT_IDLEPRIO);
689 load->inv_weight = WMULT_IDLEPRIO;
693 load->weight = scale_load(sched_prio_to_weight[prio]);
694 load->inv_weight = sched_prio_to_wmult[prio];
697 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
700 if (!(flags & ENQUEUE_RESTORE))
701 sched_info_queued(rq, p);
702 p->sched_class->enqueue_task(rq, p, flags);
705 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
708 if (!(flags & DEQUEUE_SAVE))
709 sched_info_dequeued(rq, p);
710 p->sched_class->dequeue_task(rq, p, flags);
713 void activate_task(struct rq *rq, struct task_struct *p, int flags)
715 if (task_contributes_to_load(p))
716 rq->nr_uninterruptible--;
718 enqueue_task(rq, p, flags);
721 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
723 if (task_contributes_to_load(p))
724 rq->nr_uninterruptible++;
726 dequeue_task(rq, p, flags);
729 static void update_rq_clock_task(struct rq *rq, s64 delta)
732 * In theory, the compile should just see 0 here, and optimize out the call
733 * to sched_rt_avg_update. But I don't trust it...
735 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
736 s64 steal = 0, irq_delta = 0;
738 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
739 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
742 * Since irq_time is only updated on {soft,}irq_exit, we might run into
743 * this case when a previous update_rq_clock() happened inside a
746 * When this happens, we stop ->clock_task and only update the
747 * prev_irq_time stamp to account for the part that fit, so that a next
748 * update will consume the rest. This ensures ->clock_task is
751 * It does however cause some slight miss-attribution of {soft,}irq
752 * time, a more accurate solution would be to update the irq_time using
753 * the current rq->clock timestamp, except that would require using
756 if (irq_delta > delta)
759 rq->prev_irq_time += irq_delta;
762 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
763 if (static_key_false((¶virt_steal_rq_enabled))) {
764 steal = paravirt_steal_clock(cpu_of(rq));
765 steal -= rq->prev_steal_time_rq;
767 if (unlikely(steal > delta))
770 rq->prev_steal_time_rq += steal;
775 rq->clock_task += delta;
777 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
778 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
779 sched_rt_avg_update(rq, irq_delta + steal);
783 void sched_set_stop_task(int cpu, struct task_struct *stop)
785 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
786 struct task_struct *old_stop = cpu_rq(cpu)->stop;
790 * Make it appear like a SCHED_FIFO task, its something
791 * userspace knows about and won't get confused about.
793 * Also, it will make PI more or less work without too
794 * much confusion -- but then, stop work should not
795 * rely on PI working anyway.
797 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
799 stop->sched_class = &stop_sched_class;
802 cpu_rq(cpu)->stop = stop;
806 * Reset it back to a normal scheduling class so that
807 * it can die in pieces.
809 old_stop->sched_class = &rt_sched_class;
814 * __normal_prio - return the priority that is based on the static prio
816 static inline int __normal_prio(struct task_struct *p)
818 return p->static_prio;
822 * Calculate the expected normal priority: i.e. priority
823 * without taking RT-inheritance into account. Might be
824 * boosted by interactivity modifiers. Changes upon fork,
825 * setprio syscalls, and whenever the interactivity
826 * estimator recalculates.
828 static inline int normal_prio(struct task_struct *p)
832 if (task_has_dl_policy(p))
833 prio = MAX_DL_PRIO-1;
834 else if (task_has_rt_policy(p))
835 prio = MAX_RT_PRIO-1 - p->rt_priority;
837 prio = __normal_prio(p);
842 * Calculate the current priority, i.e. the priority
843 * taken into account by the scheduler. This value might
844 * be boosted by RT tasks, or might be boosted by
845 * interactivity modifiers. Will be RT if the task got
846 * RT-boosted. If not then it returns p->normal_prio.
848 static int effective_prio(struct task_struct *p)
850 p->normal_prio = normal_prio(p);
852 * If we are RT tasks or we were boosted to RT priority,
853 * keep the priority unchanged. Otherwise, update priority
854 * to the normal priority:
856 if (!rt_prio(p->prio))
857 return p->normal_prio;
862 * task_curr - is this task currently executing on a CPU?
863 * @p: the task in question.
865 * Return: 1 if the task is currently executing. 0 otherwise.
867 inline int task_curr(const struct task_struct *p)
869 return cpu_curr(task_cpu(p)) == p;
873 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
874 * use the balance_callback list if you want balancing.
876 * this means any call to check_class_changed() must be followed by a call to
877 * balance_callback().
879 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
880 const struct sched_class *prev_class,
883 if (prev_class != p->sched_class) {
884 if (prev_class->switched_from)
885 prev_class->switched_from(rq, p);
887 p->sched_class->switched_to(rq, p);
888 } else if (oldprio != p->prio || dl_task(p))
889 p->sched_class->prio_changed(rq, p, oldprio);
892 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
894 const struct sched_class *class;
896 if (p->sched_class == rq->curr->sched_class) {
897 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
899 for_each_class(class) {
900 if (class == rq->curr->sched_class)
902 if (class == p->sched_class) {
910 * A queue event has occurred, and we're going to schedule. In
911 * this case, we can save a useless back to back clock update.
913 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
914 rq_clock_skip_update(rq, true);
919 * This is how migration works:
921 * 1) we invoke migration_cpu_stop() on the target CPU using
923 * 2) stopper starts to run (implicitly forcing the migrated thread
925 * 3) it checks whether the migrated task is still in the wrong runqueue.
926 * 4) if it's in the wrong runqueue then the migration thread removes
927 * it and puts it into the right queue.
928 * 5) stopper completes and stop_one_cpu() returns and the migration
933 * move_queued_task - move a queued task to new rq.
935 * Returns (locked) new rq. Old rq's lock is released.
937 static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
939 lockdep_assert_held(&rq->lock);
941 p->on_rq = TASK_ON_RQ_MIGRATING;
942 dequeue_task(rq, p, 0);
943 set_task_cpu(p, new_cpu);
944 raw_spin_unlock(&rq->lock);
946 rq = cpu_rq(new_cpu);
948 raw_spin_lock(&rq->lock);
949 BUG_ON(task_cpu(p) != new_cpu);
950 enqueue_task(rq, p, 0);
951 p->on_rq = TASK_ON_RQ_QUEUED;
952 check_preempt_curr(rq, p, 0);
957 struct migration_arg {
958 struct task_struct *task;
963 * Move (not current) task off this cpu, onto dest cpu. We're doing
964 * this because either it can't run here any more (set_cpus_allowed()
965 * away from this CPU, or CPU going down), or because we're
966 * attempting to rebalance this task on exec (sched_exec).
968 * So we race with normal scheduler movements, but that's OK, as long
969 * as the task is no longer on this CPU.
971 static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
973 if (unlikely(!cpu_active(dest_cpu)))
976 /* Affinity changed (again). */
977 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
980 rq = move_queued_task(rq, p, dest_cpu);
986 * migration_cpu_stop - this will be executed by a highprio stopper thread
987 * and performs thread migration by bumping thread off CPU then
988 * 'pushing' onto another runqueue.
990 static int migration_cpu_stop(void *data)
992 struct migration_arg *arg = data;
993 struct task_struct *p = arg->task;
994 struct rq *rq = this_rq();
997 * The original target cpu might have gone down and we might
998 * be on another cpu but it doesn't matter.
1000 local_irq_disable();
1002 * We need to explicitly wake pending tasks before running
1003 * __migrate_task() such that we will not miss enforcing cpus_allowed
1004 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1006 sched_ttwu_pending();
1008 raw_spin_lock(&p->pi_lock);
1009 raw_spin_lock(&rq->lock);
1011 * If task_rq(p) != rq, it cannot be migrated here, because we're
1012 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1013 * we're holding p->pi_lock.
1015 if (task_rq(p) == rq && task_on_rq_queued(p))
1016 rq = __migrate_task(rq, p, arg->dest_cpu);
1017 raw_spin_unlock(&rq->lock);
1018 raw_spin_unlock(&p->pi_lock);
1025 * sched_class::set_cpus_allowed must do the below, but is not required to
1026 * actually call this function.
1028 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1030 cpumask_copy(&p->cpus_allowed, new_mask);
1031 p->nr_cpus_allowed = cpumask_weight(new_mask);
1034 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1036 struct rq *rq = task_rq(p);
1037 bool queued, running;
1039 lockdep_assert_held(&p->pi_lock);
1041 queued = task_on_rq_queued(p);
1042 running = task_current(rq, p);
1046 * Because __kthread_bind() calls this on blocked tasks without
1049 lockdep_assert_held(&rq->lock);
1050 dequeue_task(rq, p, DEQUEUE_SAVE);
1053 put_prev_task(rq, p);
1055 p->sched_class->set_cpus_allowed(p, new_mask);
1058 p->sched_class->set_curr_task(rq);
1060 enqueue_task(rq, p, ENQUEUE_RESTORE);
1064 * Change a given task's CPU affinity. Migrate the thread to a
1065 * proper CPU and schedule it away if the CPU it's executing on
1066 * is removed from the allowed bitmask.
1068 * NOTE: the caller must have a valid reference to the task, the
1069 * task must not exit() & deallocate itself prematurely. The
1070 * call is not atomic; no spinlocks may be held.
1072 static int __set_cpus_allowed_ptr(struct task_struct *p,
1073 const struct cpumask *new_mask, bool check)
1075 unsigned long flags;
1077 unsigned int dest_cpu;
1080 rq = task_rq_lock(p, &flags);
1083 * Must re-check here, to close a race against __kthread_bind(),
1084 * sched_setaffinity() is not guaranteed to observe the flag.
1086 if (check && (p->flags & PF_NO_SETAFFINITY)) {
1091 if (cpumask_equal(&p->cpus_allowed, new_mask))
1094 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
1099 do_set_cpus_allowed(p, new_mask);
1101 /* Can the task run on the task's current CPU? If so, we're done */
1102 if (cpumask_test_cpu(task_cpu(p), new_mask))
1105 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
1106 if (task_running(rq, p) || p->state == TASK_WAKING) {
1107 struct migration_arg arg = { p, dest_cpu };
1108 /* Need help from migration thread: drop lock and wait. */
1109 task_rq_unlock(rq, p, &flags);
1110 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1111 tlb_migrate_finish(p->mm);
1113 } else if (task_on_rq_queued(p)) {
1115 * OK, since we're going to drop the lock immediately
1116 * afterwards anyway.
1118 lockdep_unpin_lock(&rq->lock);
1119 rq = move_queued_task(rq, p, dest_cpu);
1120 lockdep_pin_lock(&rq->lock);
1123 task_rq_unlock(rq, p, &flags);
1128 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1130 return __set_cpus_allowed_ptr(p, new_mask, false);
1132 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1134 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1136 #ifdef CONFIG_SCHED_DEBUG
1138 * We should never call set_task_cpu() on a blocked task,
1139 * ttwu() will sort out the placement.
1141 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1145 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1146 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1147 * time relying on p->on_rq.
1149 WARN_ON_ONCE(p->state == TASK_RUNNING &&
1150 p->sched_class == &fair_sched_class &&
1151 (p->on_rq && !task_on_rq_migrating(p)));
1153 #ifdef CONFIG_LOCKDEP
1155 * The caller should hold either p->pi_lock or rq->lock, when changing
1156 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1158 * sched_move_task() holds both and thus holding either pins the cgroup,
1161 * Furthermore, all task_rq users should acquire both locks, see
1164 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1165 lockdep_is_held(&task_rq(p)->lock)));
1169 trace_sched_migrate_task(p, new_cpu);
1171 if (task_cpu(p) != new_cpu) {
1172 if (p->sched_class->migrate_task_rq)
1173 p->sched_class->migrate_task_rq(p);
1174 p->se.nr_migrations++;
1175 perf_event_task_migrate(p);
1178 __set_task_cpu(p, new_cpu);
1181 static void __migrate_swap_task(struct task_struct *p, int cpu)
1183 if (task_on_rq_queued(p)) {
1184 struct rq *src_rq, *dst_rq;
1186 src_rq = task_rq(p);
1187 dst_rq = cpu_rq(cpu);
1189 p->on_rq = TASK_ON_RQ_MIGRATING;
1190 deactivate_task(src_rq, p, 0);
1191 set_task_cpu(p, cpu);
1192 activate_task(dst_rq, p, 0);
1193 p->on_rq = TASK_ON_RQ_QUEUED;
1194 check_preempt_curr(dst_rq, p, 0);
1197 * Task isn't running anymore; make it appear like we migrated
1198 * it before it went to sleep. This means on wakeup we make the
1199 * previous cpu our targer instead of where it really is.
1205 struct migration_swap_arg {
1206 struct task_struct *src_task, *dst_task;
1207 int src_cpu, dst_cpu;
1210 static int migrate_swap_stop(void *data)
1212 struct migration_swap_arg *arg = data;
1213 struct rq *src_rq, *dst_rq;
1216 if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1219 src_rq = cpu_rq(arg->src_cpu);
1220 dst_rq = cpu_rq(arg->dst_cpu);
1222 double_raw_lock(&arg->src_task->pi_lock,
1223 &arg->dst_task->pi_lock);
1224 double_rq_lock(src_rq, dst_rq);
1226 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1229 if (task_cpu(arg->src_task) != arg->src_cpu)
1232 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1235 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1238 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1239 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1244 double_rq_unlock(src_rq, dst_rq);
1245 raw_spin_unlock(&arg->dst_task->pi_lock);
1246 raw_spin_unlock(&arg->src_task->pi_lock);
1252 * Cross migrate two tasks
1254 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1256 struct migration_swap_arg arg;
1259 arg = (struct migration_swap_arg){
1261 .src_cpu = task_cpu(cur),
1263 .dst_cpu = task_cpu(p),
1266 if (arg.src_cpu == arg.dst_cpu)
1270 * These three tests are all lockless; this is OK since all of them
1271 * will be re-checked with proper locks held further down the line.
1273 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1276 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1279 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1282 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1283 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1290 * wait_task_inactive - wait for a thread to unschedule.
1292 * If @match_state is nonzero, it's the @p->state value just checked and
1293 * not expected to change. If it changes, i.e. @p might have woken up,
1294 * then return zero. When we succeed in waiting for @p to be off its CPU,
1295 * we return a positive number (its total switch count). If a second call
1296 * a short while later returns the same number, the caller can be sure that
1297 * @p has remained unscheduled the whole time.
1299 * The caller must ensure that the task *will* unschedule sometime soon,
1300 * else this function might spin for a *long* time. This function can't
1301 * be called with interrupts off, or it may introduce deadlock with
1302 * smp_call_function() if an IPI is sent by the same process we are
1303 * waiting to become inactive.
1305 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1307 unsigned long flags;
1308 int running, queued;
1314 * We do the initial early heuristics without holding
1315 * any task-queue locks at all. We'll only try to get
1316 * the runqueue lock when things look like they will
1322 * If the task is actively running on another CPU
1323 * still, just relax and busy-wait without holding
1326 * NOTE! Since we don't hold any locks, it's not
1327 * even sure that "rq" stays as the right runqueue!
1328 * But we don't care, since "task_running()" will
1329 * return false if the runqueue has changed and p
1330 * is actually now running somewhere else!
1332 while (task_running(rq, p)) {
1333 if (match_state && unlikely(p->state != match_state))
1339 * Ok, time to look more closely! We need the rq
1340 * lock now, to be *sure*. If we're wrong, we'll
1341 * just go back and repeat.
1343 rq = task_rq_lock(p, &flags);
1344 trace_sched_wait_task(p);
1345 running = task_running(rq, p);
1346 queued = task_on_rq_queued(p);
1348 if (!match_state || p->state == match_state)
1349 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1350 task_rq_unlock(rq, p, &flags);
1353 * If it changed from the expected state, bail out now.
1355 if (unlikely(!ncsw))
1359 * Was it really running after all now that we
1360 * checked with the proper locks actually held?
1362 * Oops. Go back and try again..
1364 if (unlikely(running)) {
1370 * It's not enough that it's not actively running,
1371 * it must be off the runqueue _entirely_, and not
1374 * So if it was still runnable (but just not actively
1375 * running right now), it's preempted, and we should
1376 * yield - it could be a while.
1378 if (unlikely(queued)) {
1379 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1381 set_current_state(TASK_UNINTERRUPTIBLE);
1382 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1387 * Ahh, all good. It wasn't running, and it wasn't
1388 * runnable, which means that it will never become
1389 * running in the future either. We're all done!
1398 * kick_process - kick a running thread to enter/exit the kernel
1399 * @p: the to-be-kicked thread
1401 * Cause a process which is running on another CPU to enter
1402 * kernel-mode, without any delay. (to get signals handled.)
1404 * NOTE: this function doesn't have to take the runqueue lock,
1405 * because all it wants to ensure is that the remote task enters
1406 * the kernel. If the IPI races and the task has been migrated
1407 * to another CPU then no harm is done and the purpose has been
1410 void kick_process(struct task_struct *p)
1416 if ((cpu != smp_processor_id()) && task_curr(p))
1417 smp_send_reschedule(cpu);
1420 EXPORT_SYMBOL_GPL(kick_process);
1423 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1425 static int select_fallback_rq(int cpu, struct task_struct *p)
1427 int nid = cpu_to_node(cpu);
1428 const struct cpumask *nodemask = NULL;
1429 enum { cpuset, possible, fail } state = cpuset;
1433 * If the node that the cpu is on has been offlined, cpu_to_node()
1434 * will return -1. There is no cpu on the node, and we should
1435 * select the cpu on the other node.
1438 nodemask = cpumask_of_node(nid);
1440 /* Look for allowed, online CPU in same node. */
1441 for_each_cpu(dest_cpu, nodemask) {
1442 if (!cpu_online(dest_cpu))
1444 if (!cpu_active(dest_cpu))
1446 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1452 /* Any allowed, online CPU? */
1453 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1454 if (!cpu_online(dest_cpu))
1456 if (!cpu_active(dest_cpu))
1461 /* No more Mr. Nice Guy. */
1464 if (IS_ENABLED(CONFIG_CPUSETS)) {
1465 cpuset_cpus_allowed_fallback(p);
1471 do_set_cpus_allowed(p, cpu_possible_mask);
1482 if (state != cpuset) {
1484 * Don't tell them about moving exiting tasks or
1485 * kernel threads (both mm NULL), since they never
1488 if (p->mm && printk_ratelimit()) {
1489 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1490 task_pid_nr(p), p->comm, cpu);
1498 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1501 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1503 lockdep_assert_held(&p->pi_lock);
1505 if (p->nr_cpus_allowed > 1)
1506 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1509 * In order not to call set_task_cpu() on a blocking task we need
1510 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1513 * Since this is common to all placement strategies, this lives here.
1515 * [ this allows ->select_task() to simply return task_cpu(p) and
1516 * not worry about this generic constraint ]
1518 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1520 cpu = select_fallback_rq(task_cpu(p), p);
1525 static void update_avg(u64 *avg, u64 sample)
1527 s64 diff = sample - *avg;
1533 static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1534 const struct cpumask *new_mask, bool check)
1536 return set_cpus_allowed_ptr(p, new_mask);
1539 #endif /* CONFIG_SMP */
1542 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1544 #ifdef CONFIG_SCHEDSTATS
1545 struct rq *rq = this_rq();
1548 int this_cpu = smp_processor_id();
1550 if (cpu == this_cpu) {
1551 schedstat_inc(rq, ttwu_local);
1552 schedstat_inc(p, se.statistics.nr_wakeups_local);
1554 struct sched_domain *sd;
1556 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1558 for_each_domain(this_cpu, sd) {
1559 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1560 schedstat_inc(sd, ttwu_wake_remote);
1567 if (wake_flags & WF_MIGRATED)
1568 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1570 #endif /* CONFIG_SMP */
1572 schedstat_inc(rq, ttwu_count);
1573 schedstat_inc(p, se.statistics.nr_wakeups);
1575 if (wake_flags & WF_SYNC)
1576 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1578 #endif /* CONFIG_SCHEDSTATS */
1581 static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1583 activate_task(rq, p, en_flags);
1584 p->on_rq = TASK_ON_RQ_QUEUED;
1586 /* if a worker is waking up, notify workqueue */
1587 if (p->flags & PF_WQ_WORKER)
1588 wq_worker_waking_up(p, cpu_of(rq));
1592 * Mark the task runnable and perform wakeup-preemption.
1595 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1597 check_preempt_curr(rq, p, wake_flags);
1598 p->state = TASK_RUNNING;
1599 trace_sched_wakeup(p);
1602 if (p->sched_class->task_woken) {
1604 * Our task @p is fully woken up and running; so its safe to
1605 * drop the rq->lock, hereafter rq is only used for statistics.
1607 lockdep_unpin_lock(&rq->lock);
1608 p->sched_class->task_woken(rq, p);
1609 lockdep_pin_lock(&rq->lock);
1612 if (rq->idle_stamp) {
1613 u64 delta = rq_clock(rq) - rq->idle_stamp;
1614 u64 max = 2*rq->max_idle_balance_cost;
1616 update_avg(&rq->avg_idle, delta);
1618 if (rq->avg_idle > max)
1627 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1629 lockdep_assert_held(&rq->lock);
1632 if (p->sched_contributes_to_load)
1633 rq->nr_uninterruptible--;
1636 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1637 ttwu_do_wakeup(rq, p, wake_flags);
1641 * Called in case the task @p isn't fully descheduled from its runqueue,
1642 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1643 * since all we need to do is flip p->state to TASK_RUNNING, since
1644 * the task is still ->on_rq.
1646 static int ttwu_remote(struct task_struct *p, int wake_flags)
1651 rq = __task_rq_lock(p);
1652 if (task_on_rq_queued(p)) {
1653 /* check_preempt_curr() may use rq clock */
1654 update_rq_clock(rq);
1655 ttwu_do_wakeup(rq, p, wake_flags);
1658 __task_rq_unlock(rq);
1664 void sched_ttwu_pending(void)
1666 struct rq *rq = this_rq();
1667 struct llist_node *llist = llist_del_all(&rq->wake_list);
1668 struct task_struct *p;
1669 unsigned long flags;
1674 raw_spin_lock_irqsave(&rq->lock, flags);
1675 lockdep_pin_lock(&rq->lock);
1678 p = llist_entry(llist, struct task_struct, wake_entry);
1679 llist = llist_next(llist);
1680 ttwu_do_activate(rq, p, 0);
1683 lockdep_unpin_lock(&rq->lock);
1684 raw_spin_unlock_irqrestore(&rq->lock, flags);
1687 void scheduler_ipi(void)
1690 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1691 * TIF_NEED_RESCHED remotely (for the first time) will also send
1694 preempt_fold_need_resched();
1696 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1700 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1701 * traditionally all their work was done from the interrupt return
1702 * path. Now that we actually do some work, we need to make sure
1705 * Some archs already do call them, luckily irq_enter/exit nest
1708 * Arguably we should visit all archs and update all handlers,
1709 * however a fair share of IPIs are still resched only so this would
1710 * somewhat pessimize the simple resched case.
1713 sched_ttwu_pending();
1716 * Check if someone kicked us for doing the nohz idle load balance.
1718 if (unlikely(got_nohz_idle_kick())) {
1719 this_rq()->idle_balance = 1;
1720 raise_softirq_irqoff(SCHED_SOFTIRQ);
1725 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1727 struct rq *rq = cpu_rq(cpu);
1729 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1730 if (!set_nr_if_polling(rq->idle))
1731 smp_send_reschedule(cpu);
1733 trace_sched_wake_idle_without_ipi(cpu);
1737 void wake_up_if_idle(int cpu)
1739 struct rq *rq = cpu_rq(cpu);
1740 unsigned long flags;
1744 if (!is_idle_task(rcu_dereference(rq->curr)))
1747 if (set_nr_if_polling(rq->idle)) {
1748 trace_sched_wake_idle_without_ipi(cpu);
1750 raw_spin_lock_irqsave(&rq->lock, flags);
1751 if (is_idle_task(rq->curr))
1752 smp_send_reschedule(cpu);
1753 /* Else cpu is not in idle, do nothing here */
1754 raw_spin_unlock_irqrestore(&rq->lock, flags);
1761 bool cpus_share_cache(int this_cpu, int that_cpu)
1763 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1765 #endif /* CONFIG_SMP */
1767 static void ttwu_queue(struct task_struct *p, int cpu)
1769 struct rq *rq = cpu_rq(cpu);
1771 #if defined(CONFIG_SMP)
1772 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1773 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1774 ttwu_queue_remote(p, cpu);
1779 raw_spin_lock(&rq->lock);
1780 lockdep_pin_lock(&rq->lock);
1781 ttwu_do_activate(rq, p, 0);
1782 lockdep_unpin_lock(&rq->lock);
1783 raw_spin_unlock(&rq->lock);
1787 * Notes on Program-Order guarantees on SMP systems.
1791 * The basic program-order guarantee on SMP systems is that when a task [t]
1792 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1793 * execution on its new cpu [c1].
1795 * For migration (of runnable tasks) this is provided by the following means:
1797 * A) UNLOCK of the rq(c0)->lock scheduling out task t
1798 * B) migration for t is required to synchronize *both* rq(c0)->lock and
1799 * rq(c1)->lock (if not at the same time, then in that order).
1800 * C) LOCK of the rq(c1)->lock scheduling in task
1802 * Transitivity guarantees that B happens after A and C after B.
1803 * Note: we only require RCpc transitivity.
1804 * Note: the cpu doing B need not be c0 or c1
1813 * UNLOCK rq(0)->lock
1815 * LOCK rq(0)->lock // orders against CPU0
1817 * UNLOCK rq(0)->lock
1821 * UNLOCK rq(1)->lock
1823 * LOCK rq(1)->lock // orders against CPU2
1826 * UNLOCK rq(1)->lock
1829 * BLOCKING -- aka. SLEEP + WAKEUP
1831 * For blocking we (obviously) need to provide the same guarantee as for
1832 * migration. However the means are completely different as there is no lock
1833 * chain to provide order. Instead we do:
1835 * 1) smp_store_release(X->on_cpu, 0)
1836 * 2) smp_cond_acquire(!X->on_cpu)
1840 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
1842 * LOCK rq(0)->lock LOCK X->pi_lock
1845 * smp_store_release(X->on_cpu, 0);
1847 * smp_cond_acquire(!X->on_cpu);
1853 * X->state = RUNNING
1854 * UNLOCK rq(2)->lock
1856 * LOCK rq(2)->lock // orders against CPU1
1859 * UNLOCK rq(2)->lock
1862 * UNLOCK rq(0)->lock
1865 * However; for wakeups there is a second guarantee we must provide, namely we
1866 * must observe the state that lead to our wakeup. That is, not only must our
1867 * task observe its own prior state, it must also observe the stores prior to
1870 * This means that any means of doing remote wakeups must order the CPU doing
1871 * the wakeup against the CPU the task is going to end up running on. This,
1872 * however, is already required for the regular Program-Order guarantee above,
1873 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire).
1878 * try_to_wake_up - wake up a thread
1879 * @p: the thread to be awakened
1880 * @state: the mask of task states that can be woken
1881 * @wake_flags: wake modifier flags (WF_*)
1883 * Put it on the run-queue if it's not already there. The "current"
1884 * thread is always on the run-queue (except when the actual
1885 * re-schedule is in progress), and as such you're allowed to do
1886 * the simpler "current->state = TASK_RUNNING" to mark yourself
1887 * runnable without the overhead of this.
1889 * Return: %true if @p was woken up, %false if it was already running.
1890 * or @state didn't match @p's state.
1893 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1895 unsigned long flags;
1896 int cpu, success = 0;
1899 * If we are going to wake up a thread waiting for CONDITION we
1900 * need to ensure that CONDITION=1 done by the caller can not be
1901 * reordered with p->state check below. This pairs with mb() in
1902 * set_current_state() the waiting thread does.
1904 smp_mb__before_spinlock();
1905 raw_spin_lock_irqsave(&p->pi_lock, flags);
1906 if (!(p->state & state))
1909 trace_sched_waking(p);
1911 success = 1; /* we're going to change ->state */
1914 if (p->on_rq && ttwu_remote(p, wake_flags))
1919 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
1920 * possible to, falsely, observe p->on_cpu == 0.
1922 * One must be running (->on_cpu == 1) in order to remove oneself
1923 * from the runqueue.
1925 * [S] ->on_cpu = 1; [L] ->on_rq
1929 * [S] ->on_rq = 0; [L] ->on_cpu
1931 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
1932 * from the consecutive calls to schedule(); the first switching to our
1933 * task, the second putting it to sleep.
1938 * If the owning (remote) cpu is still in the middle of schedule() with
1939 * this task as prev, wait until its done referencing the task.
1941 * Pairs with the smp_store_release() in finish_lock_switch().
1943 * This ensures that tasks getting woken will be fully ordered against
1944 * their previous state and preserve Program Order.
1946 smp_cond_acquire(!p->on_cpu);
1948 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1949 p->state = TASK_WAKING;
1951 if (p->sched_class->task_waking)
1952 p->sched_class->task_waking(p);
1954 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1955 if (task_cpu(p) != cpu) {
1956 wake_flags |= WF_MIGRATED;
1957 set_task_cpu(p, cpu);
1959 #endif /* CONFIG_SMP */
1963 if (schedstat_enabled())
1964 ttwu_stat(p, cpu, wake_flags);
1966 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1972 * try_to_wake_up_local - try to wake up a local task with rq lock held
1973 * @p: the thread to be awakened
1975 * Put @p on the run-queue if it's not already there. The caller must
1976 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1979 static void try_to_wake_up_local(struct task_struct *p)
1981 struct rq *rq = task_rq(p);
1983 if (WARN_ON_ONCE(rq != this_rq()) ||
1984 WARN_ON_ONCE(p == current))
1987 lockdep_assert_held(&rq->lock);
1989 if (!raw_spin_trylock(&p->pi_lock)) {
1991 * This is OK, because current is on_cpu, which avoids it being
1992 * picked for load-balance and preemption/IRQs are still
1993 * disabled avoiding further scheduler activity on it and we've
1994 * not yet picked a replacement task.
1996 lockdep_unpin_lock(&rq->lock);
1997 raw_spin_unlock(&rq->lock);
1998 raw_spin_lock(&p->pi_lock);
1999 raw_spin_lock(&rq->lock);
2000 lockdep_pin_lock(&rq->lock);
2003 if (!(p->state & TASK_NORMAL))
2006 trace_sched_waking(p);
2008 if (!task_on_rq_queued(p))
2009 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2011 ttwu_do_wakeup(rq, p, 0);
2012 if (schedstat_enabled())
2013 ttwu_stat(p, smp_processor_id(), 0);
2015 raw_spin_unlock(&p->pi_lock);
2019 * wake_up_process - Wake up a specific process
2020 * @p: The process to be woken up.
2022 * Attempt to wake up the nominated process and move it to the set of runnable
2025 * Return: 1 if the process was woken up, 0 if it was already running.
2027 * It may be assumed that this function implies a write memory barrier before
2028 * changing the task state if and only if any tasks are woken up.
2030 int wake_up_process(struct task_struct *p)
2032 return try_to_wake_up(p, TASK_NORMAL, 0);
2034 EXPORT_SYMBOL(wake_up_process);
2036 int wake_up_state(struct task_struct *p, unsigned int state)
2038 return try_to_wake_up(p, state, 0);
2042 * This function clears the sched_dl_entity static params.
2044 void __dl_clear_params(struct task_struct *p)
2046 struct sched_dl_entity *dl_se = &p->dl;
2048 dl_se->dl_runtime = 0;
2049 dl_se->dl_deadline = 0;
2050 dl_se->dl_period = 0;
2054 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 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2950 defined(CONFIG_PREEMPT_TRACER))
2952 void preempt_count_add(int val)
2954 #ifdef CONFIG_DEBUG_PREEMPT
2958 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2961 __preempt_count_add(val);
2962 #ifdef CONFIG_DEBUG_PREEMPT
2964 * Spinlock count overflowing soon?
2966 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2969 if (preempt_count() == val) {
2970 unsigned long ip = get_lock_parent_ip();
2971 #ifdef CONFIG_DEBUG_PREEMPT
2972 current->preempt_disable_ip = ip;
2974 trace_preempt_off(CALLER_ADDR0, ip);
2977 EXPORT_SYMBOL(preempt_count_add);
2978 NOKPROBE_SYMBOL(preempt_count_add);
2980 void preempt_count_sub(int val)
2982 #ifdef CONFIG_DEBUG_PREEMPT
2986 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2989 * Is the spinlock portion underflowing?
2991 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2992 !(preempt_count() & PREEMPT_MASK)))
2996 if (preempt_count() == val)
2997 trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
2998 __preempt_count_sub(val);
3000 EXPORT_SYMBOL(preempt_count_sub);
3001 NOKPROBE_SYMBOL(preempt_count_sub);
3006 * Print scheduling while atomic bug:
3008 static noinline void __schedule_bug(struct task_struct *prev)
3010 if (oops_in_progress)
3013 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3014 prev->comm, prev->pid, preempt_count());
3016 debug_show_held_locks(prev);
3018 if (irqs_disabled())
3019 print_irqtrace_events(prev);
3020 #ifdef CONFIG_DEBUG_PREEMPT
3021 if (in_atomic_preempt_off()) {
3022 pr_err("Preemption disabled at:");
3023 print_ip_sym(current->preempt_disable_ip);
3028 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
3032 * Various schedule()-time debugging checks and statistics:
3034 static inline void schedule_debug(struct task_struct *prev)
3036 #ifdef CONFIG_SCHED_STACK_END_CHECK
3037 BUG_ON(task_stack_end_corrupted(prev));
3040 if (unlikely(in_atomic_preempt_off())) {
3041 __schedule_bug(prev);
3042 preempt_count_set(PREEMPT_DISABLED);
3046 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3048 schedstat_inc(this_rq(), sched_count);
3052 * Pick up the highest-prio task:
3054 static inline struct task_struct *
3055 pick_next_task(struct rq *rq, struct task_struct *prev)
3057 const struct sched_class *class = &fair_sched_class;
3058 struct task_struct *p;
3061 * Optimization: we know that if all tasks are in
3062 * the fair class we can call that function directly:
3064 if (likely(prev->sched_class == class &&
3065 rq->nr_running == rq->cfs.h_nr_running)) {
3066 p = fair_sched_class.pick_next_task(rq, prev);
3067 if (unlikely(p == RETRY_TASK))
3070 /* assumes fair_sched_class->next == idle_sched_class */
3072 p = idle_sched_class.pick_next_task(rq, prev);
3078 for_each_class(class) {
3079 p = class->pick_next_task(rq, prev);
3081 if (unlikely(p == RETRY_TASK))
3087 BUG(); /* the idle class will always have a runnable task */
3091 * __schedule() is the main scheduler function.
3093 * The main means of driving the scheduler and thus entering this function are:
3095 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3097 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3098 * paths. For example, see arch/x86/entry_64.S.
3100 * To drive preemption between tasks, the scheduler sets the flag in timer
3101 * interrupt handler scheduler_tick().
3103 * 3. Wakeups don't really cause entry into schedule(). They add a
3104 * task to the run-queue and that's it.
3106 * Now, if the new task added to the run-queue preempts the current
3107 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3108 * called on the nearest possible occasion:
3110 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3112 * - in syscall or exception context, at the next outmost
3113 * preempt_enable(). (this might be as soon as the wake_up()'s
3116 * - in IRQ context, return from interrupt-handler to
3117 * preemptible context
3119 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3122 * - cond_resched() call
3123 * - explicit schedule() call
3124 * - return from syscall or exception to user-space
3125 * - return from interrupt-handler to user-space
3127 * WARNING: must be called with preemption disabled!
3129 static void __sched notrace __schedule(bool preempt)
3131 struct task_struct *prev, *next;
3132 unsigned long *switch_count;
3136 cpu = smp_processor_id();
3141 * do_exit() calls schedule() with preemption disabled as an exception;
3142 * however we must fix that up, otherwise the next task will see an
3143 * inconsistent (higher) preempt count.
3145 * It also avoids the below schedule_debug() test from complaining
3148 if (unlikely(prev->state == TASK_DEAD))
3149 preempt_enable_no_resched_notrace();
3151 schedule_debug(prev);
3153 if (sched_feat(HRTICK))
3156 local_irq_disable();
3157 rcu_note_context_switch();
3160 * Make sure that signal_pending_state()->signal_pending() below
3161 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3162 * done by the caller to avoid the race with signal_wake_up().
3164 smp_mb__before_spinlock();
3165 raw_spin_lock(&rq->lock);
3166 lockdep_pin_lock(&rq->lock);
3168 rq->clock_skip_update <<= 1; /* promote REQ to ACT */
3170 switch_count = &prev->nivcsw;
3171 if (!preempt && prev->state) {
3172 if (unlikely(signal_pending_state(prev->state, prev))) {
3173 prev->state = TASK_RUNNING;
3175 deactivate_task(rq, prev, DEQUEUE_SLEEP);
3179 * If a worker went to sleep, notify and ask workqueue
3180 * whether it wants to wake up a task to maintain
3183 if (prev->flags & PF_WQ_WORKER) {
3184 struct task_struct *to_wakeup;
3186 to_wakeup = wq_worker_sleeping(prev, cpu);
3188 try_to_wake_up_local(to_wakeup);
3191 switch_count = &prev->nvcsw;
3194 if (task_on_rq_queued(prev))
3195 update_rq_clock(rq);
3197 next = pick_next_task(rq, prev);
3198 clear_tsk_need_resched(prev);
3199 clear_preempt_need_resched();
3200 rq->clock_skip_update = 0;
3202 if (likely(prev != next)) {
3207 trace_sched_switch(preempt, prev, next);
3208 rq = context_switch(rq, prev, next); /* unlocks the rq */
3210 lockdep_unpin_lock(&rq->lock);
3211 raw_spin_unlock_irq(&rq->lock);
3214 balance_callback(rq);
3217 static inline void sched_submit_work(struct task_struct *tsk)
3219 if (!tsk->state || tsk_is_pi_blocked(tsk))
3222 * If we are going to sleep and we have plugged IO queued,
3223 * make sure to submit it to avoid deadlocks.
3225 if (blk_needs_flush_plug(tsk))
3226 blk_schedule_flush_plug(tsk);
3229 asmlinkage __visible void __sched schedule(void)
3231 struct task_struct *tsk = current;
3233 sched_submit_work(tsk);
3237 sched_preempt_enable_no_resched();
3238 } while (need_resched());
3240 EXPORT_SYMBOL(schedule);
3242 #ifdef CONFIG_CONTEXT_TRACKING
3243 asmlinkage __visible void __sched schedule_user(void)
3246 * If we come here after a random call to set_need_resched(),
3247 * or we have been woken up remotely but the IPI has not yet arrived,
3248 * we haven't yet exited the RCU idle mode. Do it here manually until
3249 * we find a better solution.
3251 * NB: There are buggy callers of this function. Ideally we
3252 * should warn if prev_state != CONTEXT_USER, but that will trigger
3253 * too frequently to make sense yet.
3255 enum ctx_state prev_state = exception_enter();
3257 exception_exit(prev_state);
3262 * schedule_preempt_disabled - called with preemption disabled
3264 * Returns with preemption disabled. Note: preempt_count must be 1
3266 void __sched schedule_preempt_disabled(void)
3268 sched_preempt_enable_no_resched();
3273 static void __sched notrace preempt_schedule_common(void)
3276 preempt_disable_notrace();
3278 preempt_enable_no_resched_notrace();
3281 * Check again in case we missed a preemption opportunity
3282 * between schedule and now.
3284 } while (need_resched());
3287 #ifdef CONFIG_PREEMPT
3289 * this is the entry point to schedule() from in-kernel preemption
3290 * off of preempt_enable. Kernel preemptions off return from interrupt
3291 * occur there and call schedule directly.
3293 asmlinkage __visible void __sched notrace preempt_schedule(void)
3296 * If there is a non-zero preempt_count or interrupts are disabled,
3297 * we do not want to preempt the current task. Just return..
3299 if (likely(!preemptible()))
3302 preempt_schedule_common();
3304 NOKPROBE_SYMBOL(preempt_schedule);
3305 EXPORT_SYMBOL(preempt_schedule);
3308 * preempt_schedule_notrace - preempt_schedule called by tracing
3310 * The tracing infrastructure uses preempt_enable_notrace to prevent
3311 * recursion and tracing preempt enabling caused by the tracing
3312 * infrastructure itself. But as tracing can happen in areas coming
3313 * from userspace or just about to enter userspace, a preempt enable
3314 * can occur before user_exit() is called. This will cause the scheduler
3315 * to be called when the system is still in usermode.
3317 * To prevent this, the preempt_enable_notrace will use this function
3318 * instead of preempt_schedule() to exit user context if needed before
3319 * calling the scheduler.
3321 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3323 enum ctx_state prev_ctx;
3325 if (likely(!preemptible()))
3329 preempt_disable_notrace();
3331 * Needs preempt disabled in case user_exit() is traced
3332 * and the tracer calls preempt_enable_notrace() causing
3333 * an infinite recursion.
3335 prev_ctx = exception_enter();
3337 exception_exit(prev_ctx);
3339 preempt_enable_no_resched_notrace();
3340 } while (need_resched());
3342 EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3344 #endif /* CONFIG_PREEMPT */
3347 * this is the entry point to schedule() from kernel preemption
3348 * off of irq context.
3349 * Note, that this is called and return with irqs disabled. This will
3350 * protect us against recursive calling from irq.
3352 asmlinkage __visible void __sched preempt_schedule_irq(void)
3354 enum ctx_state prev_state;
3356 /* Catch callers which need to be fixed */
3357 BUG_ON(preempt_count() || !irqs_disabled());
3359 prev_state = exception_enter();
3365 local_irq_disable();
3366 sched_preempt_enable_no_resched();
3367 } while (need_resched());
3369 exception_exit(prev_state);
3372 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3375 return try_to_wake_up(curr->private, mode, wake_flags);
3377 EXPORT_SYMBOL(default_wake_function);
3379 #ifdef CONFIG_RT_MUTEXES
3382 * rt_mutex_setprio - set the current priority of a task
3384 * @prio: prio value (kernel-internal form)
3386 * This function changes the 'effective' priority of a task. It does
3387 * not touch ->normal_prio like __setscheduler().
3389 * Used by the rt_mutex code to implement priority inheritance
3390 * logic. Call site only calls if the priority of the task changed.
3392 void rt_mutex_setprio(struct task_struct *p, int prio)
3394 int oldprio, queued, running, queue_flag = DEQUEUE_SAVE | DEQUEUE_MOVE;
3396 const struct sched_class *prev_class;
3398 BUG_ON(prio > MAX_PRIO);
3400 rq = __task_rq_lock(p);
3403 * Idle task boosting is a nono in general. There is one
3404 * exception, when PREEMPT_RT and NOHZ is active:
3406 * The idle task calls get_next_timer_interrupt() and holds
3407 * the timer wheel base->lock on the CPU and another CPU wants
3408 * to access the timer (probably to cancel it). We can safely
3409 * ignore the boosting request, as the idle CPU runs this code
3410 * with interrupts disabled and will complete the lock
3411 * protected section without being interrupted. So there is no
3412 * real need to boost.
3414 if (unlikely(p == rq->idle)) {
3415 WARN_ON(p != rq->curr);
3416 WARN_ON(p->pi_blocked_on);
3420 trace_sched_pi_setprio(p, prio);
3423 if (oldprio == prio)
3424 queue_flag &= ~DEQUEUE_MOVE;
3426 prev_class = p->sched_class;
3427 queued = task_on_rq_queued(p);
3428 running = task_current(rq, p);
3430 dequeue_task(rq, p, queue_flag);
3432 put_prev_task(rq, p);
3435 * Boosting condition are:
3436 * 1. -rt task is running and holds mutex A
3437 * --> -dl task blocks on mutex A
3439 * 2. -dl task is running and holds mutex A
3440 * --> -dl task blocks on mutex A and could preempt the
3443 if (dl_prio(prio)) {
3444 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3445 if (!dl_prio(p->normal_prio) ||
3446 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3447 p->dl.dl_boosted = 1;
3448 queue_flag |= ENQUEUE_REPLENISH;
3450 p->dl.dl_boosted = 0;
3451 p->sched_class = &dl_sched_class;
3452 } else if (rt_prio(prio)) {
3453 if (dl_prio(oldprio))
3454 p->dl.dl_boosted = 0;
3456 queue_flag |= ENQUEUE_HEAD;
3457 p->sched_class = &rt_sched_class;
3459 if (dl_prio(oldprio))
3460 p->dl.dl_boosted = 0;
3461 if (rt_prio(oldprio))
3463 p->sched_class = &fair_sched_class;
3469 p->sched_class->set_curr_task(rq);
3471 enqueue_task(rq, p, queue_flag);
3473 check_class_changed(rq, p, prev_class, oldprio);
3475 preempt_disable(); /* avoid rq from going away on us */
3476 __task_rq_unlock(rq);
3478 balance_callback(rq);
3483 void set_user_nice(struct task_struct *p, long nice)
3485 int old_prio, delta, queued;
3486 unsigned long flags;
3489 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3492 * We have to be careful, if called from sys_setpriority(),
3493 * the task might be in the middle of scheduling on another CPU.
3495 rq = task_rq_lock(p, &flags);
3497 * The RT priorities are set via sched_setscheduler(), but we still
3498 * allow the 'normal' nice value to be set - but as expected
3499 * it wont have any effect on scheduling until the task is
3500 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3502 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3503 p->static_prio = NICE_TO_PRIO(nice);
3506 queued = task_on_rq_queued(p);
3508 dequeue_task(rq, p, DEQUEUE_SAVE);
3510 p->static_prio = NICE_TO_PRIO(nice);
3513 p->prio = effective_prio(p);
3514 delta = p->prio - old_prio;
3517 enqueue_task(rq, p, ENQUEUE_RESTORE);
3519 * If the task increased its priority or is running and
3520 * lowered its priority, then reschedule its CPU:
3522 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3526 task_rq_unlock(rq, p, &flags);
3528 EXPORT_SYMBOL(set_user_nice);
3531 * can_nice - check if a task can reduce its nice value
3535 int can_nice(const struct task_struct *p, const int nice)
3537 /* convert nice value [19,-20] to rlimit style value [1,40] */
3538 int nice_rlim = nice_to_rlimit(nice);
3540 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3541 capable(CAP_SYS_NICE));
3544 #ifdef __ARCH_WANT_SYS_NICE
3547 * sys_nice - change the priority of the current process.
3548 * @increment: priority increment
3550 * sys_setpriority is a more generic, but much slower function that
3551 * does similar things.
3553 SYSCALL_DEFINE1(nice, int, increment)
3558 * Setpriority might change our priority at the same moment.
3559 * We don't have to worry. Conceptually one call occurs first
3560 * and we have a single winner.
3562 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3563 nice = task_nice(current) + increment;
3565 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3566 if (increment < 0 && !can_nice(current, nice))
3569 retval = security_task_setnice(current, nice);
3573 set_user_nice(current, nice);
3580 * task_prio - return the priority value of a given task.
3581 * @p: the task in question.
3583 * Return: The priority value as seen by users in /proc.
3584 * RT tasks are offset by -200. Normal tasks are centered
3585 * around 0, value goes from -16 to +15.
3587 int task_prio(const struct task_struct *p)
3589 return p->prio - MAX_RT_PRIO;
3593 * idle_cpu - is a given cpu idle currently?
3594 * @cpu: the processor in question.
3596 * Return: 1 if the CPU is currently idle. 0 otherwise.
3598 int idle_cpu(int cpu)
3600 struct rq *rq = cpu_rq(cpu);
3602 if (rq->curr != rq->idle)
3609 if (!llist_empty(&rq->wake_list))
3617 * idle_task - return the idle task for a given cpu.
3618 * @cpu: the processor in question.
3620 * Return: The idle task for the cpu @cpu.
3622 struct task_struct *idle_task(int cpu)
3624 return cpu_rq(cpu)->idle;
3628 * find_process_by_pid - find a process with a matching PID value.
3629 * @pid: the pid in question.
3631 * The task of @pid, if found. %NULL otherwise.
3633 static struct task_struct *find_process_by_pid(pid_t pid)
3635 return pid ? find_task_by_vpid(pid) : current;
3639 * This function initializes the sched_dl_entity of a newly becoming
3640 * SCHED_DEADLINE task.
3642 * Only the static values are considered here, the actual runtime and the
3643 * absolute deadline will be properly calculated when the task is enqueued
3644 * for the first time with its new policy.
3647 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3649 struct sched_dl_entity *dl_se = &p->dl;
3651 dl_se->dl_runtime = attr->sched_runtime;
3652 dl_se->dl_deadline = attr->sched_deadline;
3653 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3654 dl_se->flags = attr->sched_flags;
3655 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3658 * Changing the parameters of a task is 'tricky' and we're not doing
3659 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3661 * What we SHOULD do is delay the bandwidth release until the 0-lag
3662 * point. This would include retaining the task_struct until that time
3663 * and change dl_overflow() to not immediately decrement the current
3666 * Instead we retain the current runtime/deadline and let the new
3667 * parameters take effect after the current reservation period lapses.
3668 * This is safe (albeit pessimistic) because the 0-lag point is always
3669 * before the current scheduling deadline.
3671 * We can still have temporary overloads because we do not delay the
3672 * change in bandwidth until that time; so admission control is
3673 * not on the safe side. It does however guarantee tasks will never
3674 * consume more than promised.
3679 * sched_setparam() passes in -1 for its policy, to let the functions
3680 * it calls know not to change it.
3682 #define SETPARAM_POLICY -1
3684 static void __setscheduler_params(struct task_struct *p,
3685 const struct sched_attr *attr)
3687 int policy = attr->sched_policy;
3689 if (policy == SETPARAM_POLICY)
3694 if (dl_policy(policy))
3695 __setparam_dl(p, attr);
3696 else if (fair_policy(policy))
3697 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3700 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3701 * !rt_policy. Always setting this ensures that things like
3702 * getparam()/getattr() don't report silly values for !rt tasks.
3704 p->rt_priority = attr->sched_priority;
3705 p->normal_prio = normal_prio(p);
3709 /* Actually do priority change: must hold pi & rq lock. */
3710 static void __setscheduler(struct rq *rq, struct task_struct *p,
3711 const struct sched_attr *attr, bool keep_boost)
3713 __setscheduler_params(p, attr);
3716 * Keep a potential priority boosting if called from
3717 * sched_setscheduler().
3720 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
3722 p->prio = normal_prio(p);
3724 if (dl_prio(p->prio))
3725 p->sched_class = &dl_sched_class;
3726 else if (rt_prio(p->prio))
3727 p->sched_class = &rt_sched_class;
3729 p->sched_class = &fair_sched_class;
3733 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3735 struct sched_dl_entity *dl_se = &p->dl;
3737 attr->sched_priority = p->rt_priority;
3738 attr->sched_runtime = dl_se->dl_runtime;
3739 attr->sched_deadline = dl_se->dl_deadline;
3740 attr->sched_period = dl_se->dl_period;
3741 attr->sched_flags = dl_se->flags;
3745 * This function validates the new parameters of a -deadline task.
3746 * We ask for the deadline not being zero, and greater or equal
3747 * than the runtime, as well as the period of being zero or
3748 * greater than deadline. Furthermore, we have to be sure that
3749 * user parameters are above the internal resolution of 1us (we
3750 * check sched_runtime only since it is always the smaller one) and
3751 * below 2^63 ns (we have to check both sched_deadline and
3752 * sched_period, as the latter can be zero).
3755 __checkparam_dl(const struct sched_attr *attr)
3758 if (attr->sched_deadline == 0)
3762 * Since we truncate DL_SCALE bits, make sure we're at least
3765 if (attr->sched_runtime < (1ULL << DL_SCALE))
3769 * Since we use the MSB for wrap-around and sign issues, make
3770 * sure it's not set (mind that period can be equal to zero).
3772 if (attr->sched_deadline & (1ULL << 63) ||
3773 attr->sched_period & (1ULL << 63))
3776 /* runtime <= deadline <= period (if period != 0) */
3777 if ((attr->sched_period != 0 &&
3778 attr->sched_period < attr->sched_deadline) ||
3779 attr->sched_deadline < attr->sched_runtime)
3786 * check the target process has a UID that matches the current process's
3788 static bool check_same_owner(struct task_struct *p)
3790 const struct cred *cred = current_cred(), *pcred;
3794 pcred = __task_cred(p);
3795 match = (uid_eq(cred->euid, pcred->euid) ||
3796 uid_eq(cred->euid, pcred->uid));
3801 static bool dl_param_changed(struct task_struct *p,
3802 const struct sched_attr *attr)
3804 struct sched_dl_entity *dl_se = &p->dl;
3806 if (dl_se->dl_runtime != attr->sched_runtime ||
3807 dl_se->dl_deadline != attr->sched_deadline ||
3808 dl_se->dl_period != attr->sched_period ||
3809 dl_se->flags != attr->sched_flags)
3815 static int __sched_setscheduler(struct task_struct *p,
3816 const struct sched_attr *attr,
3819 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3820 MAX_RT_PRIO - 1 - attr->sched_priority;
3821 int retval, oldprio, oldpolicy = -1, queued, running;
3822 int new_effective_prio, policy = attr->sched_policy;
3823 unsigned long flags;
3824 const struct sched_class *prev_class;
3827 int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
3829 /* may grab non-irq protected spin_locks */
3830 BUG_ON(in_interrupt());
3832 /* double check policy once rq lock held */
3834 reset_on_fork = p->sched_reset_on_fork;
3835 policy = oldpolicy = p->policy;
3837 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3839 if (!valid_policy(policy))
3843 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3847 * Valid priorities for SCHED_FIFO and SCHED_RR are
3848 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3849 * SCHED_BATCH and SCHED_IDLE is 0.
3851 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3852 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3854 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3855 (rt_policy(policy) != (attr->sched_priority != 0)))
3859 * Allow unprivileged RT tasks to decrease priority:
3861 if (user && !capable(CAP_SYS_NICE)) {
3862 if (fair_policy(policy)) {
3863 if (attr->sched_nice < task_nice(p) &&
3864 !can_nice(p, attr->sched_nice))
3868 if (rt_policy(policy)) {
3869 unsigned long rlim_rtprio =
3870 task_rlimit(p, RLIMIT_RTPRIO);
3872 /* can't set/change the rt policy */
3873 if (policy != p->policy && !rlim_rtprio)
3876 /* can't increase priority */
3877 if (attr->sched_priority > p->rt_priority &&
3878 attr->sched_priority > rlim_rtprio)
3883 * Can't set/change SCHED_DEADLINE policy at all for now
3884 * (safest behavior); in the future we would like to allow
3885 * unprivileged DL tasks to increase their relative deadline
3886 * or reduce their runtime (both ways reducing utilization)
3888 if (dl_policy(policy))
3892 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3893 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3895 if (idle_policy(p->policy) && !idle_policy(policy)) {
3896 if (!can_nice(p, task_nice(p)))
3900 /* can't change other user's priorities */
3901 if (!check_same_owner(p))
3904 /* Normal users shall not reset the sched_reset_on_fork flag */
3905 if (p->sched_reset_on_fork && !reset_on_fork)
3910 retval = security_task_setscheduler(p);
3916 * make sure no PI-waiters arrive (or leave) while we are
3917 * changing the priority of the task:
3919 * To be able to change p->policy safely, the appropriate
3920 * runqueue lock must be held.
3922 rq = task_rq_lock(p, &flags);
3925 * Changing the policy of the stop threads its a very bad idea
3927 if (p == rq->stop) {
3928 task_rq_unlock(rq, p, &flags);
3933 * If not changing anything there's no need to proceed further,
3934 * but store a possible modification of reset_on_fork.
3936 if (unlikely(policy == p->policy)) {
3937 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3939 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3941 if (dl_policy(policy) && dl_param_changed(p, attr))
3944 p->sched_reset_on_fork = reset_on_fork;
3945 task_rq_unlock(rq, p, &flags);
3951 #ifdef CONFIG_RT_GROUP_SCHED
3953 * Do not allow realtime tasks into groups that have no runtime
3956 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3957 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3958 !task_group_is_autogroup(task_group(p))) {
3959 task_rq_unlock(rq, p, &flags);
3964 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3965 cpumask_t *span = rq->rd->span;
3968 * Don't allow tasks with an affinity mask smaller than
3969 * the entire root_domain to become SCHED_DEADLINE. We
3970 * will also fail if there's no bandwidth available.
3972 if (!cpumask_subset(span, &p->cpus_allowed) ||
3973 rq->rd->dl_bw.bw == 0) {
3974 task_rq_unlock(rq, p, &flags);
3981 /* recheck policy now with rq lock held */
3982 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3983 policy = oldpolicy = -1;
3984 task_rq_unlock(rq, p, &flags);
3989 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3990 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3993 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3994 task_rq_unlock(rq, p, &flags);
3998 p->sched_reset_on_fork = reset_on_fork;
4003 * Take priority boosted tasks into account. If the new
4004 * effective priority is unchanged, we just store the new
4005 * normal parameters and do not touch the scheduler class and
4006 * the runqueue. This will be done when the task deboost
4009 new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
4010 if (new_effective_prio == oldprio)
4011 queue_flags &= ~DEQUEUE_MOVE;
4014 queued = task_on_rq_queued(p);
4015 running = task_current(rq, p);
4017 dequeue_task(rq, p, queue_flags);
4019 put_prev_task(rq, p);
4021 prev_class = p->sched_class;
4022 __setscheduler(rq, p, attr, pi);
4025 p->sched_class->set_curr_task(rq);
4028 * We enqueue to tail when the priority of a task is
4029 * increased (user space view).
4031 if (oldprio < p->prio)
4032 queue_flags |= ENQUEUE_HEAD;
4034 enqueue_task(rq, p, queue_flags);
4037 check_class_changed(rq, p, prev_class, oldprio);
4038 preempt_disable(); /* avoid rq from going away on us */
4039 task_rq_unlock(rq, p, &flags);
4042 rt_mutex_adjust_pi(p);
4045 * Run balance callbacks after we've adjusted the PI chain.
4047 balance_callback(rq);
4053 static int _sched_setscheduler(struct task_struct *p, int policy,
4054 const struct sched_param *param, bool check)
4056 struct sched_attr attr = {
4057 .sched_policy = policy,
4058 .sched_priority = param->sched_priority,
4059 .sched_nice = PRIO_TO_NICE(p->static_prio),
4062 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4063 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4064 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4065 policy &= ~SCHED_RESET_ON_FORK;
4066 attr.sched_policy = policy;
4069 return __sched_setscheduler(p, &attr, check, true);
4072 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4073 * @p: the task in question.
4074 * @policy: new policy.
4075 * @param: structure containing the new RT priority.
4077 * Return: 0 on success. An error code otherwise.
4079 * NOTE that the task may be already dead.
4081 int sched_setscheduler(struct task_struct *p, int policy,
4082 const struct sched_param *param)
4084 return _sched_setscheduler(p, policy, param, true);
4086 EXPORT_SYMBOL_GPL(sched_setscheduler);
4088 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4090 return __sched_setscheduler(p, attr, true, true);
4092 EXPORT_SYMBOL_GPL(sched_setattr);
4095 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4096 * @p: the task in question.
4097 * @policy: new policy.
4098 * @param: structure containing the new RT priority.
4100 * Just like sched_setscheduler, only don't bother checking if the
4101 * current context has permission. For example, this is needed in
4102 * stop_machine(): we create temporary high priority worker threads,
4103 * but our caller might not have that capability.
4105 * Return: 0 on success. An error code otherwise.
4107 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4108 const struct sched_param *param)
4110 return _sched_setscheduler(p, policy, param, false);
4112 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4115 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4117 struct sched_param lparam;
4118 struct task_struct *p;
4121 if (!param || pid < 0)
4123 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4128 p = find_process_by_pid(pid);
4130 retval = sched_setscheduler(p, policy, &lparam);
4137 * Mimics kernel/events/core.c perf_copy_attr().
4139 static int sched_copy_attr(struct sched_attr __user *uattr,
4140 struct sched_attr *attr)
4145 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4149 * zero the full structure, so that a short copy will be nice.
4151 memset(attr, 0, sizeof(*attr));
4153 ret = get_user(size, &uattr->size);
4157 if (size > PAGE_SIZE) /* silly large */
4160 if (!size) /* abi compat */
4161 size = SCHED_ATTR_SIZE_VER0;
4163 if (size < SCHED_ATTR_SIZE_VER0)
4167 * If we're handed a bigger struct than we know of,
4168 * ensure all the unknown bits are 0 - i.e. new
4169 * user-space does not rely on any kernel feature
4170 * extensions we dont know about yet.
4172 if (size > sizeof(*attr)) {
4173 unsigned char __user *addr;
4174 unsigned char __user *end;
4177 addr = (void __user *)uattr + sizeof(*attr);
4178 end = (void __user *)uattr + size;
4180 for (; addr < end; addr++) {
4181 ret = get_user(val, addr);
4187 size = sizeof(*attr);
4190 ret = copy_from_user(attr, uattr, size);
4195 * XXX: do we want to be lenient like existing syscalls; or do we want
4196 * to be strict and return an error on out-of-bounds values?
4198 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4203 put_user(sizeof(*attr), &uattr->size);
4208 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4209 * @pid: the pid in question.
4210 * @policy: new policy.
4211 * @param: structure containing the new RT priority.
4213 * Return: 0 on success. An error code otherwise.
4215 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4216 struct sched_param __user *, param)
4218 /* negative values for policy are not valid */
4222 return do_sched_setscheduler(pid, policy, param);
4226 * sys_sched_setparam - set/change the RT priority of a thread
4227 * @pid: the pid in question.
4228 * @param: structure containing the new RT priority.
4230 * Return: 0 on success. An error code otherwise.
4232 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4234 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4238 * sys_sched_setattr - same as above, but with extended sched_attr
4239 * @pid: the pid in question.
4240 * @uattr: structure containing the extended parameters.
4241 * @flags: for future extension.
4243 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4244 unsigned int, flags)
4246 struct sched_attr attr;
4247 struct task_struct *p;
4250 if (!uattr || pid < 0 || flags)
4253 retval = sched_copy_attr(uattr, &attr);
4257 if ((int)attr.sched_policy < 0)
4262 p = find_process_by_pid(pid);
4264 retval = sched_setattr(p, &attr);
4271 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4272 * @pid: the pid in question.
4274 * Return: On success, the policy of the thread. Otherwise, a negative error
4277 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4279 struct task_struct *p;
4287 p = find_process_by_pid(pid);
4289 retval = security_task_getscheduler(p);
4292 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4299 * sys_sched_getparam - get the RT priority of a thread
4300 * @pid: the pid in question.
4301 * @param: structure containing the RT priority.
4303 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4306 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4308 struct sched_param lp = { .sched_priority = 0 };
4309 struct task_struct *p;
4312 if (!param || pid < 0)
4316 p = find_process_by_pid(pid);
4321 retval = security_task_getscheduler(p);
4325 if (task_has_rt_policy(p))
4326 lp.sched_priority = p->rt_priority;
4330 * This one might sleep, we cannot do it with a spinlock held ...
4332 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4341 static int sched_read_attr(struct sched_attr __user *uattr,
4342 struct sched_attr *attr,
4347 if (!access_ok(VERIFY_WRITE, uattr, usize))
4351 * If we're handed a smaller struct than we know of,
4352 * ensure all the unknown bits are 0 - i.e. old
4353 * user-space does not get uncomplete information.
4355 if (usize < sizeof(*attr)) {
4356 unsigned char *addr;
4359 addr = (void *)attr + usize;
4360 end = (void *)attr + sizeof(*attr);
4362 for (; addr < end; addr++) {
4370 ret = copy_to_user(uattr, attr, attr->size);
4378 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4379 * @pid: the pid in question.
4380 * @uattr: structure containing the extended parameters.
4381 * @size: sizeof(attr) for fwd/bwd comp.
4382 * @flags: for future extension.
4384 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4385 unsigned int, size, unsigned int, flags)
4387 struct sched_attr attr = {
4388 .size = sizeof(struct sched_attr),
4390 struct task_struct *p;
4393 if (!uattr || pid < 0 || size > PAGE_SIZE ||
4394 size < SCHED_ATTR_SIZE_VER0 || flags)
4398 p = find_process_by_pid(pid);
4403 retval = security_task_getscheduler(p);
4407 attr.sched_policy = p->policy;
4408 if (p->sched_reset_on_fork)
4409 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4410 if (task_has_dl_policy(p))
4411 __getparam_dl(p, &attr);
4412 else if (task_has_rt_policy(p))
4413 attr.sched_priority = p->rt_priority;
4415 attr.sched_nice = task_nice(p);
4419 retval = sched_read_attr(uattr, &attr, size);
4427 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4429 cpumask_var_t cpus_allowed, new_mask;
4430 struct task_struct *p;
4435 p = find_process_by_pid(pid);
4441 /* Prevent p going away */
4445 if (p->flags & PF_NO_SETAFFINITY) {
4449 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4453 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4455 goto out_free_cpus_allowed;
4458 if (!check_same_owner(p)) {
4460 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4462 goto out_free_new_mask;
4467 retval = security_task_setscheduler(p);
4469 goto out_free_new_mask;
4472 cpuset_cpus_allowed(p, cpus_allowed);
4473 cpumask_and(new_mask, in_mask, cpus_allowed);
4476 * Since bandwidth control happens on root_domain basis,
4477 * if admission test is enabled, we only admit -deadline
4478 * tasks allowed to run on all the CPUs in the task's
4482 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4484 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4487 goto out_free_new_mask;
4493 retval = __set_cpus_allowed_ptr(p, new_mask, true);
4496 cpuset_cpus_allowed(p, cpus_allowed);
4497 if (!cpumask_subset(new_mask, cpus_allowed)) {
4499 * We must have raced with a concurrent cpuset
4500 * update. Just reset the cpus_allowed to the
4501 * cpuset's cpus_allowed
4503 cpumask_copy(new_mask, cpus_allowed);
4508 free_cpumask_var(new_mask);
4509 out_free_cpus_allowed:
4510 free_cpumask_var(cpus_allowed);
4516 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4517 struct cpumask *new_mask)
4519 if (len < cpumask_size())
4520 cpumask_clear(new_mask);
4521 else if (len > cpumask_size())
4522 len = cpumask_size();
4524 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4528 * sys_sched_setaffinity - set the cpu affinity of a process
4529 * @pid: pid of the process
4530 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4531 * @user_mask_ptr: user-space pointer to the new cpu mask
4533 * Return: 0 on success. An error code otherwise.
4535 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4536 unsigned long __user *, user_mask_ptr)
4538 cpumask_var_t new_mask;
4541 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4544 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4546 retval = sched_setaffinity(pid, new_mask);
4547 free_cpumask_var(new_mask);
4551 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4553 struct task_struct *p;
4554 unsigned long flags;
4560 p = find_process_by_pid(pid);
4564 retval = security_task_getscheduler(p);
4568 raw_spin_lock_irqsave(&p->pi_lock, flags);
4569 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4570 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4579 * sys_sched_getaffinity - get the cpu affinity of a process
4580 * @pid: pid of the process
4581 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4582 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4584 * Return: 0 on success. An error code otherwise.
4586 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4587 unsigned long __user *, user_mask_ptr)
4592 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4594 if (len & (sizeof(unsigned long)-1))
4597 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4600 ret = sched_getaffinity(pid, mask);
4602 size_t retlen = min_t(size_t, len, cpumask_size());
4604 if (copy_to_user(user_mask_ptr, mask, retlen))
4609 free_cpumask_var(mask);
4615 * sys_sched_yield - yield the current processor to other threads.
4617 * This function yields the current CPU to other tasks. If there are no
4618 * other threads running on this CPU then this function will return.
4622 SYSCALL_DEFINE0(sched_yield)
4624 struct rq *rq = this_rq_lock();
4626 schedstat_inc(rq, yld_count);
4627 current->sched_class->yield_task(rq);
4630 * Since we are going to call schedule() anyway, there's
4631 * no need to preempt or enable interrupts:
4633 __release(rq->lock);
4634 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4635 do_raw_spin_unlock(&rq->lock);
4636 sched_preempt_enable_no_resched();
4643 int __sched _cond_resched(void)
4645 if (should_resched(0)) {
4646 preempt_schedule_common();
4651 EXPORT_SYMBOL(_cond_resched);
4654 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4655 * call schedule, and on return reacquire the lock.
4657 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4658 * operations here to prevent schedule() from being called twice (once via
4659 * spin_unlock(), once by hand).
4661 int __cond_resched_lock(spinlock_t *lock)
4663 int resched = should_resched(PREEMPT_LOCK_OFFSET);
4666 lockdep_assert_held(lock);
4668 if (spin_needbreak(lock) || resched) {
4671 preempt_schedule_common();
4679 EXPORT_SYMBOL(__cond_resched_lock);
4681 int __sched __cond_resched_softirq(void)
4683 BUG_ON(!in_softirq());
4685 if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4687 preempt_schedule_common();
4693 EXPORT_SYMBOL(__cond_resched_softirq);
4696 * yield - yield the current processor to other threads.
4698 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4700 * The scheduler is at all times free to pick the calling task as the most
4701 * eligible task to run, if removing the yield() call from your code breaks
4702 * it, its already broken.
4704 * Typical broken usage is:
4709 * where one assumes that yield() will let 'the other' process run that will
4710 * make event true. If the current task is a SCHED_FIFO task that will never
4711 * happen. Never use yield() as a progress guarantee!!
4713 * If you want to use yield() to wait for something, use wait_event().
4714 * If you want to use yield() to be 'nice' for others, use cond_resched().
4715 * If you still want to use yield(), do not!
4717 void __sched yield(void)
4719 set_current_state(TASK_RUNNING);
4722 EXPORT_SYMBOL(yield);
4725 * yield_to - yield the current processor to another thread in
4726 * your thread group, or accelerate that thread toward the
4727 * processor it's on.
4729 * @preempt: whether task preemption is allowed or not
4731 * It's the caller's job to ensure that the target task struct
4732 * can't go away on us before we can do any checks.
4735 * true (>0) if we indeed boosted the target task.
4736 * false (0) if we failed to boost the target.
4737 * -ESRCH if there's no task to yield to.
4739 int __sched yield_to(struct task_struct *p, bool preempt)
4741 struct task_struct *curr = current;
4742 struct rq *rq, *p_rq;
4743 unsigned long flags;
4746 local_irq_save(flags);
4752 * If we're the only runnable task on the rq and target rq also
4753 * has only one task, there's absolutely no point in yielding.
4755 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4760 double_rq_lock(rq, p_rq);
4761 if (task_rq(p) != p_rq) {
4762 double_rq_unlock(rq, p_rq);
4766 if (!curr->sched_class->yield_to_task)
4769 if (curr->sched_class != p->sched_class)
4772 if (task_running(p_rq, p) || p->state)
4775 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4777 schedstat_inc(rq, yld_count);
4779 * Make p's CPU reschedule; pick_next_entity takes care of
4782 if (preempt && rq != p_rq)
4787 double_rq_unlock(rq, p_rq);
4789 local_irq_restore(flags);
4796 EXPORT_SYMBOL_GPL(yield_to);
4799 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4800 * that process accounting knows that this is a task in IO wait state.
4802 long __sched io_schedule_timeout(long timeout)
4804 int old_iowait = current->in_iowait;
4808 current->in_iowait = 1;
4809 blk_schedule_flush_plug(current);
4811 delayacct_blkio_start();
4813 atomic_inc(&rq->nr_iowait);
4814 ret = schedule_timeout(timeout);
4815 current->in_iowait = old_iowait;
4816 atomic_dec(&rq->nr_iowait);
4817 delayacct_blkio_end();
4821 EXPORT_SYMBOL(io_schedule_timeout);
4824 * sys_sched_get_priority_max - return maximum RT priority.
4825 * @policy: scheduling class.
4827 * Return: On success, this syscall returns the maximum
4828 * rt_priority that can be used by a given scheduling class.
4829 * On failure, a negative error code is returned.
4831 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4838 ret = MAX_USER_RT_PRIO-1;
4840 case SCHED_DEADLINE:
4851 * sys_sched_get_priority_min - return minimum RT priority.
4852 * @policy: scheduling class.
4854 * Return: On success, this syscall returns the minimum
4855 * rt_priority that can be used by a given scheduling class.
4856 * On failure, a negative error code is returned.
4858 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4867 case SCHED_DEADLINE:
4877 * sys_sched_rr_get_interval - return the default timeslice of a process.
4878 * @pid: pid of the process.
4879 * @interval: userspace pointer to the timeslice value.
4881 * this syscall writes the default timeslice value of a given process
4882 * into the user-space timespec buffer. A value of '0' means infinity.
4884 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4887 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4888 struct timespec __user *, interval)
4890 struct task_struct *p;
4891 unsigned int time_slice;
4892 unsigned long flags;
4902 p = find_process_by_pid(pid);
4906 retval = security_task_getscheduler(p);
4910 rq = task_rq_lock(p, &flags);
4912 if (p->sched_class->get_rr_interval)
4913 time_slice = p->sched_class->get_rr_interval(rq, p);
4914 task_rq_unlock(rq, p, &flags);
4917 jiffies_to_timespec(time_slice, &t);
4918 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4926 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4928 void sched_show_task(struct task_struct *p)
4930 unsigned long free = 0;
4932 unsigned long state = p->state;
4935 state = __ffs(state) + 1;
4936 printk(KERN_INFO "%-15.15s %c", p->comm,
4937 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4938 #if BITS_PER_LONG == 32
4939 if (state == TASK_RUNNING)
4940 printk(KERN_CONT " running ");
4942 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4944 if (state == TASK_RUNNING)
4945 printk(KERN_CONT " running task ");
4947 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4949 #ifdef CONFIG_DEBUG_STACK_USAGE
4950 free = stack_not_used(p);
4955 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4957 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4958 task_pid_nr(p), ppid,
4959 (unsigned long)task_thread_info(p)->flags);
4961 print_worker_info(KERN_INFO, p);
4962 show_stack(p, NULL);
4965 void show_state_filter(unsigned long state_filter)
4967 struct task_struct *g, *p;
4969 #if BITS_PER_LONG == 32
4971 " task PC stack pid father\n");
4974 " task PC stack pid father\n");
4977 for_each_process_thread(g, p) {
4979 * reset the NMI-timeout, listing all files on a slow
4980 * console might take a lot of time:
4982 touch_nmi_watchdog();
4983 if (!state_filter || (p->state & state_filter))
4987 touch_all_softlockup_watchdogs();
4989 #ifdef CONFIG_SCHED_DEBUG
4990 sysrq_sched_debug_show();
4994 * Only show locks if all tasks are dumped:
4997 debug_show_all_locks();
5000 void init_idle_bootup_task(struct task_struct *idle)
5002 idle->sched_class = &idle_sched_class;
5006 * init_idle - set up an idle thread for a given CPU
5007 * @idle: task in question
5008 * @cpu: cpu the idle task belongs to
5010 * NOTE: this function does not set the idle thread's NEED_RESCHED
5011 * flag, to make booting more robust.
5013 void init_idle(struct task_struct *idle, int cpu)
5015 struct rq *rq = cpu_rq(cpu);
5016 unsigned long flags;
5018 raw_spin_lock_irqsave(&idle->pi_lock, flags);
5019 raw_spin_lock(&rq->lock);
5021 __sched_fork(0, idle);
5022 idle->state = TASK_RUNNING;
5023 idle->se.exec_start = sched_clock();
5025 kasan_unpoison_task_stack(idle);
5029 * Its possible that init_idle() gets called multiple times on a task,
5030 * in that case do_set_cpus_allowed() will not do the right thing.
5032 * And since this is boot we can forgo the serialization.
5034 set_cpus_allowed_common(idle, cpumask_of(cpu));
5037 * We're having a chicken and egg problem, even though we are
5038 * holding rq->lock, the cpu isn't yet set to this cpu so the
5039 * lockdep check in task_group() will fail.
5041 * Similar case to sched_fork(). / Alternatively we could
5042 * use task_rq_lock() here and obtain the other rq->lock.
5047 __set_task_cpu(idle, cpu);
5050 rq->curr = rq->idle = idle;
5051 idle->on_rq = TASK_ON_RQ_QUEUED;
5055 raw_spin_unlock(&rq->lock);
5056 raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5058 /* Set the preempt count _outside_ the spinlocks! */
5059 init_idle_preempt_count(idle, cpu);
5062 * The idle tasks have their own, simple scheduling class:
5064 idle->sched_class = &idle_sched_class;
5065 ftrace_graph_init_idle_task(idle, cpu);
5066 vtime_init_idle(idle, cpu);
5068 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5072 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5073 const struct cpumask *trial)
5075 int ret = 1, trial_cpus;
5076 struct dl_bw *cur_dl_b;
5077 unsigned long flags;
5079 if (!cpumask_weight(cur))
5082 rcu_read_lock_sched();
5083 cur_dl_b = dl_bw_of(cpumask_any(cur));
5084 trial_cpus = cpumask_weight(trial);
5086 raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
5087 if (cur_dl_b->bw != -1 &&
5088 cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
5090 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5091 rcu_read_unlock_sched();
5096 int task_can_attach(struct task_struct *p,
5097 const struct cpumask *cs_cpus_allowed)
5102 * Kthreads which disallow setaffinity shouldn't be moved
5103 * to a new cpuset; we don't want to change their cpu
5104 * affinity and isolating such threads by their set of
5105 * allowed nodes is unnecessary. Thus, cpusets are not
5106 * applicable for such threads. This prevents checking for
5107 * success of set_cpus_allowed_ptr() on all attached tasks
5108 * before cpus_allowed may be changed.
5110 if (p->flags & PF_NO_SETAFFINITY) {
5116 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5118 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
5123 unsigned long flags;
5125 rcu_read_lock_sched();
5126 dl_b = dl_bw_of(dest_cpu);
5127 raw_spin_lock_irqsave(&dl_b->lock, flags);
5128 cpus = dl_bw_cpus(dest_cpu);
5129 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
5134 * We reserve space for this task in the destination
5135 * root_domain, as we can't fail after this point.
5136 * We will free resources in the source root_domain
5137 * later on (see set_cpus_allowed_dl()).
5139 __dl_add(dl_b, p->dl.dl_bw);
5141 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5142 rcu_read_unlock_sched();
5152 #ifdef CONFIG_NUMA_BALANCING
5153 /* Migrate current task p to target_cpu */
5154 int migrate_task_to(struct task_struct *p, int target_cpu)
5156 struct migration_arg arg = { p, target_cpu };
5157 int curr_cpu = task_cpu(p);
5159 if (curr_cpu == target_cpu)
5162 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
5165 /* TODO: This is not properly updating schedstats */
5167 trace_sched_move_numa(p, curr_cpu, target_cpu);
5168 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5172 * Requeue a task on a given node and accurately track the number of NUMA
5173 * tasks on the runqueues
5175 void sched_setnuma(struct task_struct *p, int nid)
5178 unsigned long flags;
5179 bool queued, running;
5181 rq = task_rq_lock(p, &flags);
5182 queued = task_on_rq_queued(p);
5183 running = task_current(rq, p);
5186 dequeue_task(rq, p, DEQUEUE_SAVE);
5188 put_prev_task(rq, p);
5190 p->numa_preferred_nid = nid;
5193 p->sched_class->set_curr_task(rq);
5195 enqueue_task(rq, p, ENQUEUE_RESTORE);
5196 task_rq_unlock(rq, p, &flags);
5198 #endif /* CONFIG_NUMA_BALANCING */
5200 #ifdef CONFIG_HOTPLUG_CPU
5202 * Ensures that the idle task is using init_mm right before its cpu goes
5205 void idle_task_exit(void)
5207 struct mm_struct *mm = current->active_mm;
5209 BUG_ON(cpu_online(smp_processor_id()));
5211 if (mm != &init_mm) {
5212 switch_mm(mm, &init_mm, current);
5213 finish_arch_post_lock_switch();
5219 * Since this CPU is going 'away' for a while, fold any nr_active delta
5220 * we might have. Assumes we're called after migrate_tasks() so that the
5221 * nr_active count is stable.
5223 * Also see the comment "Global load-average calculations".
5225 static void calc_load_migrate(struct rq *rq)
5227 long delta = calc_load_fold_active(rq);
5229 atomic_long_add(delta, &calc_load_tasks);
5232 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5236 static const struct sched_class fake_sched_class = {
5237 .put_prev_task = put_prev_task_fake,
5240 static struct task_struct fake_task = {
5242 * Avoid pull_{rt,dl}_task()
5244 .prio = MAX_PRIO + 1,
5245 .sched_class = &fake_sched_class,
5249 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5250 * try_to_wake_up()->select_task_rq().
5252 * Called with rq->lock held even though we'er in stop_machine() and
5253 * there's no concurrency possible, we hold the required locks anyway
5254 * because of lock validation efforts.
5256 static void migrate_tasks(struct rq *dead_rq)
5258 struct rq *rq = dead_rq;
5259 struct task_struct *next, *stop = rq->stop;
5263 * Fudge the rq selection such that the below task selection loop
5264 * doesn't get stuck on the currently eligible stop task.
5266 * We're currently inside stop_machine() and the rq is either stuck
5267 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5268 * either way we should never end up calling schedule() until we're
5274 * put_prev_task() and pick_next_task() sched
5275 * class method both need to have an up-to-date
5276 * value of rq->clock[_task]
5278 update_rq_clock(rq);
5282 * There's this thread running, bail when that's the only
5285 if (rq->nr_running == 1)
5289 * pick_next_task assumes pinned rq->lock.
5291 lockdep_pin_lock(&rq->lock);
5292 next = pick_next_task(rq, &fake_task);
5294 next->sched_class->put_prev_task(rq, next);
5297 * Rules for changing task_struct::cpus_allowed are holding
5298 * both pi_lock and rq->lock, such that holding either
5299 * stabilizes the mask.
5301 * Drop rq->lock is not quite as disastrous as it usually is
5302 * because !cpu_active at this point, which means load-balance
5303 * will not interfere. Also, stop-machine.
5305 lockdep_unpin_lock(&rq->lock);
5306 raw_spin_unlock(&rq->lock);
5307 raw_spin_lock(&next->pi_lock);
5308 raw_spin_lock(&rq->lock);
5311 * Since we're inside stop-machine, _nothing_ should have
5312 * changed the task, WARN if weird stuff happened, because in
5313 * that case the above rq->lock drop is a fail too.
5315 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5316 raw_spin_unlock(&next->pi_lock);
5320 /* Find suitable destination for @next, with force if needed. */
5321 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5323 rq = __migrate_task(rq, next, dest_cpu);
5324 if (rq != dead_rq) {
5325 raw_spin_unlock(&rq->lock);
5327 raw_spin_lock(&rq->lock);
5329 raw_spin_unlock(&next->pi_lock);
5334 #endif /* CONFIG_HOTPLUG_CPU */
5336 static void set_rq_online(struct rq *rq)
5339 const struct sched_class *class;
5341 cpumask_set_cpu(rq->cpu, rq->rd->online);
5344 for_each_class(class) {
5345 if (class->rq_online)
5346 class->rq_online(rq);
5351 static void set_rq_offline(struct rq *rq)
5354 const struct sched_class *class;
5356 for_each_class(class) {
5357 if (class->rq_offline)
5358 class->rq_offline(rq);
5361 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5367 * migration_call - callback that gets triggered when a CPU is added.
5368 * Here we can start up the necessary migration thread for the new CPU.
5371 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5373 int cpu = (long)hcpu;
5374 unsigned long flags;
5375 struct rq *rq = cpu_rq(cpu);
5377 switch (action & ~CPU_TASKS_FROZEN) {
5379 case CPU_UP_PREPARE:
5380 rq->calc_load_update = calc_load_update;
5384 /* Update our root-domain */
5385 raw_spin_lock_irqsave(&rq->lock, flags);
5387 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5391 raw_spin_unlock_irqrestore(&rq->lock, flags);
5394 #ifdef CONFIG_HOTPLUG_CPU
5396 sched_ttwu_pending();
5397 /* Update our root-domain */
5398 raw_spin_lock_irqsave(&rq->lock, flags);
5400 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5404 BUG_ON(rq->nr_running != 1); /* the migration thread */
5405 raw_spin_unlock_irqrestore(&rq->lock, flags);
5409 calc_load_migrate(rq);
5414 update_max_interval();
5420 * Register at high priority so that task migration (migrate_all_tasks)
5421 * happens before everything else. This has to be lower priority than
5422 * the notifier in the perf_event subsystem, though.
5424 static struct notifier_block migration_notifier = {
5425 .notifier_call = migration_call,
5426 .priority = CPU_PRI_MIGRATION,
5429 static void set_cpu_rq_start_time(void)
5431 int cpu = smp_processor_id();
5432 struct rq *rq = cpu_rq(cpu);
5433 rq->age_stamp = sched_clock_cpu(cpu);
5436 static int sched_cpu_active(struct notifier_block *nfb,
5437 unsigned long action, void *hcpu)
5439 int cpu = (long)hcpu;
5441 switch (action & ~CPU_TASKS_FROZEN) {
5443 set_cpu_rq_start_time();
5448 * At this point a starting CPU has marked itself as online via
5449 * set_cpu_online(). But it might not yet have marked itself
5450 * as active, which is essential from here on.
5452 set_cpu_active(cpu, true);
5453 stop_machine_unpark(cpu);
5456 case CPU_DOWN_FAILED:
5457 set_cpu_active(cpu, true);
5465 static int sched_cpu_inactive(struct notifier_block *nfb,
5466 unsigned long action, void *hcpu)
5468 switch (action & ~CPU_TASKS_FROZEN) {
5469 case CPU_DOWN_PREPARE:
5470 set_cpu_active((long)hcpu, false);
5477 static int __init migration_init(void)
5479 void *cpu = (void *)(long)smp_processor_id();
5482 /* Initialize migration for the boot CPU */
5483 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5484 BUG_ON(err == NOTIFY_BAD);
5485 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5486 register_cpu_notifier(&migration_notifier);
5488 /* Register cpu active notifiers */
5489 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5490 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5494 early_initcall(migration_init);
5496 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5498 #ifdef CONFIG_SCHED_DEBUG
5500 static __read_mostly int sched_debug_enabled;
5502 static int __init sched_debug_setup(char *str)
5504 sched_debug_enabled = 1;
5508 early_param("sched_debug", sched_debug_setup);
5510 static inline bool sched_debug(void)
5512 return sched_debug_enabled;
5515 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5516 struct cpumask *groupmask)
5518 struct sched_group *group = sd->groups;
5520 cpumask_clear(groupmask);
5522 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5524 if (!(sd->flags & SD_LOAD_BALANCE)) {
5525 printk("does not load-balance\n");
5527 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5532 printk(KERN_CONT "span %*pbl level %s\n",
5533 cpumask_pr_args(sched_domain_span(sd)), sd->name);
5535 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5536 printk(KERN_ERR "ERROR: domain->span does not contain "
5539 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5540 printk(KERN_ERR "ERROR: domain->groups does not contain"
5544 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5548 printk(KERN_ERR "ERROR: group is NULL\n");
5552 if (!cpumask_weight(sched_group_cpus(group))) {
5553 printk(KERN_CONT "\n");
5554 printk(KERN_ERR "ERROR: empty group\n");
5558 if (!(sd->flags & SD_OVERLAP) &&
5559 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5560 printk(KERN_CONT "\n");
5561 printk(KERN_ERR "ERROR: repeated CPUs\n");
5565 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5567 printk(KERN_CONT " %*pbl",
5568 cpumask_pr_args(sched_group_cpus(group)));
5569 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5570 printk(KERN_CONT " (cpu_capacity = %d)",
5571 group->sgc->capacity);
5574 group = group->next;
5575 } while (group != sd->groups);
5576 printk(KERN_CONT "\n");
5578 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5579 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5582 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5583 printk(KERN_ERR "ERROR: parent span is not a superset "
5584 "of domain->span\n");
5588 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5592 if (!sched_debug_enabled)
5596 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5600 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5603 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5611 #else /* !CONFIG_SCHED_DEBUG */
5612 # define sched_domain_debug(sd, cpu) do { } while (0)
5613 static inline bool sched_debug(void)
5617 #endif /* CONFIG_SCHED_DEBUG */
5619 static int sd_degenerate(struct sched_domain *sd)
5621 if (cpumask_weight(sched_domain_span(sd)) == 1)
5624 /* Following flags need at least 2 groups */
5625 if (sd->flags & (SD_LOAD_BALANCE |
5626 SD_BALANCE_NEWIDLE |
5629 SD_SHARE_CPUCAPACITY |
5630 SD_SHARE_PKG_RESOURCES |
5631 SD_SHARE_POWERDOMAIN)) {
5632 if (sd->groups != sd->groups->next)
5636 /* Following flags don't use groups */
5637 if (sd->flags & (SD_WAKE_AFFINE))
5644 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5646 unsigned long cflags = sd->flags, pflags = parent->flags;
5648 if (sd_degenerate(parent))
5651 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5654 /* Flags needing groups don't count if only 1 group in parent */
5655 if (parent->groups == parent->groups->next) {
5656 pflags &= ~(SD_LOAD_BALANCE |
5657 SD_BALANCE_NEWIDLE |
5660 SD_SHARE_CPUCAPACITY |
5661 SD_SHARE_PKG_RESOURCES |
5663 SD_SHARE_POWERDOMAIN);
5664 if (nr_node_ids == 1)
5665 pflags &= ~SD_SERIALIZE;
5667 if (~cflags & pflags)
5673 static void free_rootdomain(struct rcu_head *rcu)
5675 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5677 cpupri_cleanup(&rd->cpupri);
5678 cpudl_cleanup(&rd->cpudl);
5679 free_cpumask_var(rd->dlo_mask);
5680 free_cpumask_var(rd->rto_mask);
5681 free_cpumask_var(rd->online);
5682 free_cpumask_var(rd->span);
5686 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5688 struct root_domain *old_rd = NULL;
5689 unsigned long flags;
5691 raw_spin_lock_irqsave(&rq->lock, flags);
5696 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5699 cpumask_clear_cpu(rq->cpu, old_rd->span);
5702 * If we dont want to free the old_rd yet then
5703 * set old_rd to NULL to skip the freeing later
5706 if (!atomic_dec_and_test(&old_rd->refcount))
5710 atomic_inc(&rd->refcount);
5713 cpumask_set_cpu(rq->cpu, rd->span);
5714 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5717 raw_spin_unlock_irqrestore(&rq->lock, flags);
5720 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5723 static int init_rootdomain(struct root_domain *rd)
5725 memset(rd, 0, sizeof(*rd));
5727 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5729 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5731 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5733 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5736 init_dl_bw(&rd->dl_bw);
5737 if (cpudl_init(&rd->cpudl) != 0)
5740 if (cpupri_init(&rd->cpupri) != 0)
5745 free_cpumask_var(rd->rto_mask);
5747 free_cpumask_var(rd->dlo_mask);
5749 free_cpumask_var(rd->online);
5751 free_cpumask_var(rd->span);
5757 * By default the system creates a single root-domain with all cpus as
5758 * members (mimicking the global state we have today).
5760 struct root_domain def_root_domain;
5762 static void init_defrootdomain(void)
5764 init_rootdomain(&def_root_domain);
5766 atomic_set(&def_root_domain.refcount, 1);
5769 static struct root_domain *alloc_rootdomain(void)
5771 struct root_domain *rd;
5773 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5777 if (init_rootdomain(rd) != 0) {
5785 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5787 struct sched_group *tmp, *first;
5796 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5801 } while (sg != first);
5804 static void free_sched_domain(struct rcu_head *rcu)
5806 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5809 * If its an overlapping domain it has private groups, iterate and
5812 if (sd->flags & SD_OVERLAP) {
5813 free_sched_groups(sd->groups, 1);
5814 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5815 kfree(sd->groups->sgc);
5821 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5823 call_rcu(&sd->rcu, free_sched_domain);
5826 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5828 for (; sd; sd = sd->parent)
5829 destroy_sched_domain(sd, cpu);
5833 * Keep a special pointer to the highest sched_domain that has
5834 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5835 * allows us to avoid some pointer chasing select_idle_sibling().
5837 * Also keep a unique ID per domain (we use the first cpu number in
5838 * the cpumask of the domain), this allows us to quickly tell if
5839 * two cpus are in the same cache domain, see cpus_share_cache().
5841 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5842 DEFINE_PER_CPU(int, sd_llc_size);
5843 DEFINE_PER_CPU(int, sd_llc_id);
5844 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5845 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5846 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5848 static void update_top_cache_domain(int cpu)
5850 struct sched_domain *sd;
5851 struct sched_domain *busy_sd = NULL;
5855 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5857 id = cpumask_first(sched_domain_span(sd));
5858 size = cpumask_weight(sched_domain_span(sd));
5859 busy_sd = sd->parent; /* sd_busy */
5861 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5863 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5864 per_cpu(sd_llc_size, cpu) = size;
5865 per_cpu(sd_llc_id, cpu) = id;
5867 sd = lowest_flag_domain(cpu, SD_NUMA);
5868 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5870 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5871 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5875 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5876 * hold the hotplug lock.
5879 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5881 struct rq *rq = cpu_rq(cpu);
5882 struct sched_domain *tmp;
5884 /* Remove the sched domains which do not contribute to scheduling. */
5885 for (tmp = sd; tmp; ) {
5886 struct sched_domain *parent = tmp->parent;
5890 if (sd_parent_degenerate(tmp, parent)) {
5891 tmp->parent = parent->parent;
5893 parent->parent->child = tmp;
5895 * Transfer SD_PREFER_SIBLING down in case of a
5896 * degenerate parent; the spans match for this
5897 * so the property transfers.
5899 if (parent->flags & SD_PREFER_SIBLING)
5900 tmp->flags |= SD_PREFER_SIBLING;
5901 destroy_sched_domain(parent, cpu);
5906 if (sd && sd_degenerate(sd)) {
5909 destroy_sched_domain(tmp, cpu);
5914 sched_domain_debug(sd, cpu);
5916 rq_attach_root(rq, rd);
5918 rcu_assign_pointer(rq->sd, sd);
5919 destroy_sched_domains(tmp, cpu);
5921 update_top_cache_domain(cpu);
5924 /* Setup the mask of cpus configured for isolated domains */
5925 static int __init isolated_cpu_setup(char *str)
5929 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5930 ret = cpulist_parse(str, cpu_isolated_map);
5932 pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids);
5937 __setup("isolcpus=", isolated_cpu_setup);
5940 struct sched_domain ** __percpu sd;
5941 struct root_domain *rd;
5952 * Build an iteration mask that can exclude certain CPUs from the upwards
5955 * Asymmetric node setups can result in situations where the domain tree is of
5956 * unequal depth, make sure to skip domains that already cover the entire
5959 * In that case build_sched_domains() will have terminated the iteration early
5960 * and our sibling sd spans will be empty. Domains should always include the
5961 * cpu they're built on, so check that.
5964 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5966 const struct cpumask *span = sched_domain_span(sd);
5967 struct sd_data *sdd = sd->private;
5968 struct sched_domain *sibling;
5971 for_each_cpu(i, span) {
5972 sibling = *per_cpu_ptr(sdd->sd, i);
5973 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5976 cpumask_set_cpu(i, sched_group_mask(sg));
5981 * Return the canonical balance cpu for this group, this is the first cpu
5982 * of this group that's also in the iteration mask.
5984 int group_balance_cpu(struct sched_group *sg)
5986 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5990 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5992 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5993 const struct cpumask *span = sched_domain_span(sd);
5994 struct cpumask *covered = sched_domains_tmpmask;
5995 struct sd_data *sdd = sd->private;
5996 struct sched_domain *sibling;
5999 cpumask_clear(covered);
6001 for_each_cpu(i, span) {
6002 struct cpumask *sg_span;
6004 if (cpumask_test_cpu(i, covered))
6007 sibling = *per_cpu_ptr(sdd->sd, i);
6009 /* See the comment near build_group_mask(). */
6010 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6013 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6014 GFP_KERNEL, cpu_to_node(cpu));
6019 sg_span = sched_group_cpus(sg);
6021 cpumask_copy(sg_span, sched_domain_span(sibling->child));
6023 cpumask_set_cpu(i, sg_span);
6025 cpumask_or(covered, covered, sg_span);
6027 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
6028 if (atomic_inc_return(&sg->sgc->ref) == 1)
6029 build_group_mask(sd, sg);
6032 * Initialize sgc->capacity such that even if we mess up the
6033 * domains and no possible iteration will get us here, we won't
6036 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6039 * Make sure the first group of this domain contains the
6040 * canonical balance cpu. Otherwise the sched_domain iteration
6041 * breaks. See update_sg_lb_stats().
6043 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
6044 group_balance_cpu(sg) == cpu)
6054 sd->groups = groups;
6059 free_sched_groups(first, 0);
6064 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
6066 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6067 struct sched_domain *child = sd->child;
6070 cpu = cpumask_first(sched_domain_span(child));
6073 *sg = *per_cpu_ptr(sdd->sg, cpu);
6074 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
6075 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6082 * build_sched_groups will build a circular linked list of the groups
6083 * covered by the given span, and will set each group's ->cpumask correctly,
6084 * and ->cpu_capacity to 0.
6086 * Assumes the sched_domain tree is fully constructed
6089 build_sched_groups(struct sched_domain *sd, int cpu)
6091 struct sched_group *first = NULL, *last = NULL;
6092 struct sd_data *sdd = sd->private;
6093 const struct cpumask *span = sched_domain_span(sd);
6094 struct cpumask *covered;
6097 get_group(cpu, sdd, &sd->groups);
6098 atomic_inc(&sd->groups->ref);
6100 if (cpu != cpumask_first(span))
6103 lockdep_assert_held(&sched_domains_mutex);
6104 covered = sched_domains_tmpmask;
6106 cpumask_clear(covered);
6108 for_each_cpu(i, span) {
6109 struct sched_group *sg;
6112 if (cpumask_test_cpu(i, covered))
6115 group = get_group(i, sdd, &sg);
6116 cpumask_setall(sched_group_mask(sg));
6118 for_each_cpu(j, span) {
6119 if (get_group(j, sdd, NULL) != group)
6122 cpumask_set_cpu(j, covered);
6123 cpumask_set_cpu(j, sched_group_cpus(sg));
6138 * Initialize sched groups cpu_capacity.
6140 * cpu_capacity indicates the capacity of sched group, which is used while
6141 * distributing the load between different sched groups in a sched domain.
6142 * Typically cpu_capacity for all the groups in a sched domain will be same
6143 * unless there are asymmetries in the topology. If there are asymmetries,
6144 * group having more cpu_capacity will pickup more load compared to the
6145 * group having less cpu_capacity.
6147 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6149 struct sched_group *sg = sd->groups;
6154 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
6156 } while (sg != sd->groups);
6158 if (cpu != group_balance_cpu(sg))
6161 update_group_capacity(sd, cpu);
6162 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6166 * Initializers for schedule domains
6167 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6170 static int default_relax_domain_level = -1;
6171 int sched_domain_level_max;
6173 static int __init setup_relax_domain_level(char *str)
6175 if (kstrtoint(str, 0, &default_relax_domain_level))
6176 pr_warn("Unable to set relax_domain_level\n");
6180 __setup("relax_domain_level=", setup_relax_domain_level);
6182 static void set_domain_attribute(struct sched_domain *sd,
6183 struct sched_domain_attr *attr)
6187 if (!attr || attr->relax_domain_level < 0) {
6188 if (default_relax_domain_level < 0)
6191 request = default_relax_domain_level;
6193 request = attr->relax_domain_level;
6194 if (request < sd->level) {
6195 /* turn off idle balance on this domain */
6196 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6198 /* turn on idle balance on this domain */
6199 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6203 static void __sdt_free(const struct cpumask *cpu_map);
6204 static int __sdt_alloc(const struct cpumask *cpu_map);
6206 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6207 const struct cpumask *cpu_map)
6211 if (!atomic_read(&d->rd->refcount))
6212 free_rootdomain(&d->rd->rcu); /* fall through */
6214 free_percpu(d->sd); /* fall through */
6216 __sdt_free(cpu_map); /* fall through */
6222 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6223 const struct cpumask *cpu_map)
6225 memset(d, 0, sizeof(*d));
6227 if (__sdt_alloc(cpu_map))
6228 return sa_sd_storage;
6229 d->sd = alloc_percpu(struct sched_domain *);
6231 return sa_sd_storage;
6232 d->rd = alloc_rootdomain();
6235 return sa_rootdomain;
6239 * NULL the sd_data elements we've used to build the sched_domain and
6240 * sched_group structure so that the subsequent __free_domain_allocs()
6241 * will not free the data we're using.
6243 static void claim_allocations(int cpu, struct sched_domain *sd)
6245 struct sd_data *sdd = sd->private;
6247 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6248 *per_cpu_ptr(sdd->sd, cpu) = NULL;
6250 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6251 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6253 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6254 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6258 static int sched_domains_numa_levels;
6259 enum numa_topology_type sched_numa_topology_type;
6260 static int *sched_domains_numa_distance;
6261 int sched_max_numa_distance;
6262 static struct cpumask ***sched_domains_numa_masks;
6263 static int sched_domains_curr_level;
6267 * SD_flags allowed in topology descriptions.
6269 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6270 * SD_SHARE_PKG_RESOURCES - describes shared caches
6271 * SD_NUMA - describes NUMA topologies
6272 * SD_SHARE_POWERDOMAIN - describes shared power domain
6275 * SD_ASYM_PACKING - describes SMT quirks
6277 #define TOPOLOGY_SD_FLAGS \
6278 (SD_SHARE_CPUCAPACITY | \
6279 SD_SHARE_PKG_RESOURCES | \
6282 SD_SHARE_POWERDOMAIN)
6284 static struct sched_domain *
6285 sd_init(struct sched_domain_topology_level *tl, int cpu)
6287 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6288 int sd_weight, sd_flags = 0;
6292 * Ugly hack to pass state to sd_numa_mask()...
6294 sched_domains_curr_level = tl->numa_level;
6297 sd_weight = cpumask_weight(tl->mask(cpu));
6300 sd_flags = (*tl->sd_flags)();
6301 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6302 "wrong sd_flags in topology description\n"))
6303 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6305 *sd = (struct sched_domain){
6306 .min_interval = sd_weight,
6307 .max_interval = 2*sd_weight,
6309 .imbalance_pct = 125,
6311 .cache_nice_tries = 0,
6318 .flags = 1*SD_LOAD_BALANCE
6319 | 1*SD_BALANCE_NEWIDLE
6324 | 0*SD_SHARE_CPUCAPACITY
6325 | 0*SD_SHARE_PKG_RESOURCES
6327 | 0*SD_PREFER_SIBLING
6332 .last_balance = jiffies,
6333 .balance_interval = sd_weight,
6335 .max_newidle_lb_cost = 0,
6336 .next_decay_max_lb_cost = jiffies,
6337 #ifdef CONFIG_SCHED_DEBUG
6343 * Convert topological properties into behaviour.
6346 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6347 sd->flags |= SD_PREFER_SIBLING;
6348 sd->imbalance_pct = 110;
6349 sd->smt_gain = 1178; /* ~15% */
6351 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6352 sd->imbalance_pct = 117;
6353 sd->cache_nice_tries = 1;
6357 } else if (sd->flags & SD_NUMA) {
6358 sd->cache_nice_tries = 2;
6362 sd->flags |= SD_SERIALIZE;
6363 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6364 sd->flags &= ~(SD_BALANCE_EXEC |
6371 sd->flags |= SD_PREFER_SIBLING;
6372 sd->cache_nice_tries = 1;
6377 sd->private = &tl->data;
6383 * Topology list, bottom-up.
6385 static struct sched_domain_topology_level default_topology[] = {
6386 #ifdef CONFIG_SCHED_SMT
6387 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6389 #ifdef CONFIG_SCHED_MC
6390 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6392 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6396 static struct sched_domain_topology_level *sched_domain_topology =
6399 #define for_each_sd_topology(tl) \
6400 for (tl = sched_domain_topology; tl->mask; tl++)
6402 void set_sched_topology(struct sched_domain_topology_level *tl)
6404 sched_domain_topology = tl;
6409 static const struct cpumask *sd_numa_mask(int cpu)
6411 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6414 static void sched_numa_warn(const char *str)
6416 static int done = false;
6424 printk(KERN_WARNING "ERROR: %s\n\n", str);
6426 for (i = 0; i < nr_node_ids; i++) {
6427 printk(KERN_WARNING " ");
6428 for (j = 0; j < nr_node_ids; j++)
6429 printk(KERN_CONT "%02d ", node_distance(i,j));
6430 printk(KERN_CONT "\n");
6432 printk(KERN_WARNING "\n");
6435 bool find_numa_distance(int distance)
6439 if (distance == node_distance(0, 0))
6442 for (i = 0; i < sched_domains_numa_levels; i++) {
6443 if (sched_domains_numa_distance[i] == distance)
6451 * A system can have three types of NUMA topology:
6452 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6453 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6454 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6456 * The difference between a glueless mesh topology and a backplane
6457 * topology lies in whether communication between not directly
6458 * connected nodes goes through intermediary nodes (where programs
6459 * could run), or through backplane controllers. This affects
6460 * placement of programs.
6462 * The type of topology can be discerned with the following tests:
6463 * - If the maximum distance between any nodes is 1 hop, the system
6464 * is directly connected.
6465 * - If for two nodes A and B, located N > 1 hops away from each other,
6466 * there is an intermediary node C, which is < N hops away from both
6467 * nodes A and B, the system is a glueless mesh.
6469 static void init_numa_topology_type(void)
6473 n = sched_max_numa_distance;
6475 if (sched_domains_numa_levels <= 1) {
6476 sched_numa_topology_type = NUMA_DIRECT;
6480 for_each_online_node(a) {
6481 for_each_online_node(b) {
6482 /* Find two nodes furthest removed from each other. */
6483 if (node_distance(a, b) < n)
6486 /* Is there an intermediary node between a and b? */
6487 for_each_online_node(c) {
6488 if (node_distance(a, c) < n &&
6489 node_distance(b, c) < n) {
6490 sched_numa_topology_type =
6496 sched_numa_topology_type = NUMA_BACKPLANE;
6502 static void sched_init_numa(void)
6504 int next_distance, curr_distance = node_distance(0, 0);
6505 struct sched_domain_topology_level *tl;
6509 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6510 if (!sched_domains_numa_distance)
6514 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6515 * unique distances in the node_distance() table.
6517 * Assumes node_distance(0,j) includes all distances in
6518 * node_distance(i,j) in order to avoid cubic time.
6520 next_distance = curr_distance;
6521 for (i = 0; i < nr_node_ids; i++) {
6522 for (j = 0; j < nr_node_ids; j++) {
6523 for (k = 0; k < nr_node_ids; k++) {
6524 int distance = node_distance(i, k);
6526 if (distance > curr_distance &&
6527 (distance < next_distance ||
6528 next_distance == curr_distance))
6529 next_distance = distance;
6532 * While not a strong assumption it would be nice to know
6533 * about cases where if node A is connected to B, B is not
6534 * equally connected to A.
6536 if (sched_debug() && node_distance(k, i) != distance)
6537 sched_numa_warn("Node-distance not symmetric");
6539 if (sched_debug() && i && !find_numa_distance(distance))
6540 sched_numa_warn("Node-0 not representative");
6542 if (next_distance != curr_distance) {
6543 sched_domains_numa_distance[level++] = next_distance;
6544 sched_domains_numa_levels = level;
6545 curr_distance = next_distance;
6550 * In case of sched_debug() we verify the above assumption.
6560 * 'level' contains the number of unique distances, excluding the
6561 * identity distance node_distance(i,i).
6563 * The sched_domains_numa_distance[] array includes the actual distance
6568 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6569 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6570 * the array will contain less then 'level' members. This could be
6571 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6572 * in other functions.
6574 * We reset it to 'level' at the end of this function.
6576 sched_domains_numa_levels = 0;
6578 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6579 if (!sched_domains_numa_masks)
6583 * Now for each level, construct a mask per node which contains all
6584 * cpus of nodes that are that many hops away from us.
6586 for (i = 0; i < level; i++) {
6587 sched_domains_numa_masks[i] =
6588 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6589 if (!sched_domains_numa_masks[i])
6592 for (j = 0; j < nr_node_ids; j++) {
6593 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6597 sched_domains_numa_masks[i][j] = mask;
6600 if (node_distance(j, k) > sched_domains_numa_distance[i])
6603 cpumask_or(mask, mask, cpumask_of_node(k));
6608 /* Compute default topology size */
6609 for (i = 0; sched_domain_topology[i].mask; i++);
6611 tl = kzalloc((i + level + 1) *
6612 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6617 * Copy the default topology bits..
6619 for (i = 0; sched_domain_topology[i].mask; i++)
6620 tl[i] = sched_domain_topology[i];
6623 * .. and append 'j' levels of NUMA goodness.
6625 for (j = 0; j < level; i++, j++) {
6626 tl[i] = (struct sched_domain_topology_level){
6627 .mask = sd_numa_mask,
6628 .sd_flags = cpu_numa_flags,
6629 .flags = SDTL_OVERLAP,
6635 sched_domain_topology = tl;
6637 sched_domains_numa_levels = level;
6638 sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6640 init_numa_topology_type();
6643 static void sched_domains_numa_masks_set(int cpu)
6646 int node = cpu_to_node(cpu);
6648 for (i = 0; i < sched_domains_numa_levels; i++) {
6649 for (j = 0; j < nr_node_ids; j++) {
6650 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6651 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6656 static void sched_domains_numa_masks_clear(int cpu)
6659 for (i = 0; i < sched_domains_numa_levels; i++) {
6660 for (j = 0; j < nr_node_ids; j++)
6661 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6666 * Update sched_domains_numa_masks[level][node] array when new cpus
6669 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6670 unsigned long action,
6673 int cpu = (long)hcpu;
6675 switch (action & ~CPU_TASKS_FROZEN) {
6677 sched_domains_numa_masks_set(cpu);
6681 sched_domains_numa_masks_clear(cpu);
6691 static inline void sched_init_numa(void)
6695 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6696 unsigned long action,
6701 #endif /* CONFIG_NUMA */
6703 static int __sdt_alloc(const struct cpumask *cpu_map)
6705 struct sched_domain_topology_level *tl;
6708 for_each_sd_topology(tl) {
6709 struct sd_data *sdd = &tl->data;
6711 sdd->sd = alloc_percpu(struct sched_domain *);
6715 sdd->sg = alloc_percpu(struct sched_group *);
6719 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6723 for_each_cpu(j, cpu_map) {
6724 struct sched_domain *sd;
6725 struct sched_group *sg;
6726 struct sched_group_capacity *sgc;
6728 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6729 GFP_KERNEL, cpu_to_node(j));
6733 *per_cpu_ptr(sdd->sd, j) = sd;
6735 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6736 GFP_KERNEL, cpu_to_node(j));
6742 *per_cpu_ptr(sdd->sg, j) = sg;
6744 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6745 GFP_KERNEL, cpu_to_node(j));
6749 *per_cpu_ptr(sdd->sgc, j) = sgc;
6756 static void __sdt_free(const struct cpumask *cpu_map)
6758 struct sched_domain_topology_level *tl;
6761 for_each_sd_topology(tl) {
6762 struct sd_data *sdd = &tl->data;
6764 for_each_cpu(j, cpu_map) {
6765 struct sched_domain *sd;
6768 sd = *per_cpu_ptr(sdd->sd, j);
6769 if (sd && (sd->flags & SD_OVERLAP))
6770 free_sched_groups(sd->groups, 0);
6771 kfree(*per_cpu_ptr(sdd->sd, j));
6775 kfree(*per_cpu_ptr(sdd->sg, j));
6777 kfree(*per_cpu_ptr(sdd->sgc, j));
6779 free_percpu(sdd->sd);
6781 free_percpu(sdd->sg);
6783 free_percpu(sdd->sgc);
6788 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6789 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6790 struct sched_domain *child, int cpu)
6792 struct sched_domain *sd = sd_init(tl, cpu);
6796 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6798 sd->level = child->level + 1;
6799 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6803 if (!cpumask_subset(sched_domain_span(child),
6804 sched_domain_span(sd))) {
6805 pr_err("BUG: arch topology borken\n");
6806 #ifdef CONFIG_SCHED_DEBUG
6807 pr_err(" the %s domain not a subset of the %s domain\n",
6808 child->name, sd->name);
6810 /* Fixup, ensure @sd has at least @child cpus. */
6811 cpumask_or(sched_domain_span(sd),
6812 sched_domain_span(sd),
6813 sched_domain_span(child));
6817 set_domain_attribute(sd, attr);
6823 * Build sched domains for a given set of cpus and attach the sched domains
6824 * to the individual cpus
6826 static int build_sched_domains(const struct cpumask *cpu_map,
6827 struct sched_domain_attr *attr)
6829 enum s_alloc alloc_state;
6830 struct sched_domain *sd;
6832 int i, ret = -ENOMEM;
6834 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6835 if (alloc_state != sa_rootdomain)
6838 /* Set up domains for cpus specified by the cpu_map. */
6839 for_each_cpu(i, cpu_map) {
6840 struct sched_domain_topology_level *tl;
6843 for_each_sd_topology(tl) {
6844 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6845 if (tl == sched_domain_topology)
6846 *per_cpu_ptr(d.sd, i) = sd;
6847 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6848 sd->flags |= SD_OVERLAP;
6849 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6854 /* Build the groups for the domains */
6855 for_each_cpu(i, cpu_map) {
6856 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6857 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6858 if (sd->flags & SD_OVERLAP) {
6859 if (build_overlap_sched_groups(sd, i))
6862 if (build_sched_groups(sd, i))
6868 /* Calculate CPU capacity for physical packages and nodes */
6869 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6870 if (!cpumask_test_cpu(i, cpu_map))
6873 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6874 claim_allocations(i, sd);
6875 init_sched_groups_capacity(i, sd);
6879 /* Attach the domains */
6881 for_each_cpu(i, cpu_map) {
6882 sd = *per_cpu_ptr(d.sd, i);
6883 cpu_attach_domain(sd, d.rd, i);
6889 __free_domain_allocs(&d, alloc_state, cpu_map);
6893 static cpumask_var_t *doms_cur; /* current sched domains */
6894 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6895 static struct sched_domain_attr *dattr_cur;
6896 /* attribues of custom domains in 'doms_cur' */
6899 * Special case: If a kmalloc of a doms_cur partition (array of
6900 * cpumask) fails, then fallback to a single sched domain,
6901 * as determined by the single cpumask fallback_doms.
6903 static cpumask_var_t fallback_doms;
6906 * arch_update_cpu_topology lets virtualized architectures update the
6907 * cpu core maps. It is supposed to return 1 if the topology changed
6908 * or 0 if it stayed the same.
6910 int __weak arch_update_cpu_topology(void)
6915 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6918 cpumask_var_t *doms;
6920 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6923 for (i = 0; i < ndoms; i++) {
6924 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6925 free_sched_domains(doms, i);
6932 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6935 for (i = 0; i < ndoms; i++)
6936 free_cpumask_var(doms[i]);
6941 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6942 * For now this just excludes isolated cpus, but could be used to
6943 * exclude other special cases in the future.
6945 static int init_sched_domains(const struct cpumask *cpu_map)
6949 arch_update_cpu_topology();
6951 doms_cur = alloc_sched_domains(ndoms_cur);
6953 doms_cur = &fallback_doms;
6954 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6955 err = build_sched_domains(doms_cur[0], NULL);
6956 register_sched_domain_sysctl();
6962 * Detach sched domains from a group of cpus specified in cpu_map
6963 * These cpus will now be attached to the NULL domain
6965 static void detach_destroy_domains(const struct cpumask *cpu_map)
6970 for_each_cpu(i, cpu_map)
6971 cpu_attach_domain(NULL, &def_root_domain, i);
6975 /* handle null as "default" */
6976 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6977 struct sched_domain_attr *new, int idx_new)
6979 struct sched_domain_attr tmp;
6986 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6987 new ? (new + idx_new) : &tmp,
6988 sizeof(struct sched_domain_attr));
6992 * Partition sched domains as specified by the 'ndoms_new'
6993 * cpumasks in the array doms_new[] of cpumasks. This compares
6994 * doms_new[] to the current sched domain partitioning, doms_cur[].
6995 * It destroys each deleted domain and builds each new domain.
6997 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6998 * The masks don't intersect (don't overlap.) We should setup one
6999 * sched domain for each mask. CPUs not in any of the cpumasks will
7000 * not be load balanced. If the same cpumask appears both in the
7001 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7004 * The passed in 'doms_new' should be allocated using
7005 * alloc_sched_domains. This routine takes ownership of it and will
7006 * free_sched_domains it when done with it. If the caller failed the
7007 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7008 * and partition_sched_domains() will fallback to the single partition
7009 * 'fallback_doms', it also forces the domains to be rebuilt.
7011 * If doms_new == NULL it will be replaced with cpu_online_mask.
7012 * ndoms_new == 0 is a special case for destroying existing domains,
7013 * and it will not create the default domain.
7015 * Call with hotplug lock held
7017 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7018 struct sched_domain_attr *dattr_new)
7023 mutex_lock(&sched_domains_mutex);
7025 /* always unregister in case we don't destroy any domains */
7026 unregister_sched_domain_sysctl();
7028 /* Let architecture update cpu core mappings. */
7029 new_topology = arch_update_cpu_topology();
7031 n = doms_new ? ndoms_new : 0;
7033 /* Destroy deleted domains */
7034 for (i = 0; i < ndoms_cur; i++) {
7035 for (j = 0; j < n && !new_topology; j++) {
7036 if (cpumask_equal(doms_cur[i], doms_new[j])
7037 && dattrs_equal(dattr_cur, i, dattr_new, j))
7040 /* no match - a current sched domain not in new doms_new[] */
7041 detach_destroy_domains(doms_cur[i]);
7047 if (doms_new == NULL) {
7049 doms_new = &fallback_doms;
7050 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7051 WARN_ON_ONCE(dattr_new);
7054 /* Build new domains */
7055 for (i = 0; i < ndoms_new; i++) {
7056 for (j = 0; j < n && !new_topology; j++) {
7057 if (cpumask_equal(doms_new[i], doms_cur[j])
7058 && dattrs_equal(dattr_new, i, dattr_cur, j))
7061 /* no match - add a new doms_new */
7062 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
7067 /* Remember the new sched domains */
7068 if (doms_cur != &fallback_doms)
7069 free_sched_domains(doms_cur, ndoms_cur);
7070 kfree(dattr_cur); /* kfree(NULL) is safe */
7071 doms_cur = doms_new;
7072 dattr_cur = dattr_new;
7073 ndoms_cur = ndoms_new;
7075 register_sched_domain_sysctl();
7077 mutex_unlock(&sched_domains_mutex);
7080 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
7083 * Update cpusets according to cpu_active mask. If cpusets are
7084 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7085 * around partition_sched_domains().
7087 * If we come here as part of a suspend/resume, don't touch cpusets because we
7088 * want to restore it back to its original state upon resume anyway.
7090 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
7094 case CPU_ONLINE_FROZEN:
7095 case CPU_DOWN_FAILED_FROZEN:
7098 * num_cpus_frozen tracks how many CPUs are involved in suspend
7099 * resume sequence. As long as this is not the last online
7100 * operation in the resume sequence, just build a single sched
7101 * domain, ignoring cpusets.
7104 if (likely(num_cpus_frozen)) {
7105 partition_sched_domains(1, NULL, NULL);
7110 * This is the last CPU online operation. So fall through and
7111 * restore the original sched domains by considering the
7112 * cpuset configurations.
7116 cpuset_update_active_cpus(true);
7124 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
7127 unsigned long flags;
7128 long cpu = (long)hcpu;
7134 case CPU_DOWN_PREPARE:
7135 rcu_read_lock_sched();
7136 dl_b = dl_bw_of(cpu);
7138 raw_spin_lock_irqsave(&dl_b->lock, flags);
7139 cpus = dl_bw_cpus(cpu);
7140 overflow = __dl_overflow(dl_b, cpus, 0, 0);
7141 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7143 rcu_read_unlock_sched();
7146 return notifier_from_errno(-EBUSY);
7147 cpuset_update_active_cpus(false);
7149 case CPU_DOWN_PREPARE_FROZEN:
7151 partition_sched_domains(1, NULL, NULL);
7159 void __init sched_init_smp(void)
7161 cpumask_var_t non_isolated_cpus;
7163 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7164 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7169 * There's no userspace yet to cause hotplug operations; hence all the
7170 * cpu masks are stable and all blatant races in the below code cannot
7173 mutex_lock(&sched_domains_mutex);
7174 init_sched_domains(cpu_active_mask);
7175 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
7176 if (cpumask_empty(non_isolated_cpus))
7177 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7178 mutex_unlock(&sched_domains_mutex);
7180 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
7181 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
7182 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
7186 /* Move init over to a non-isolated CPU */
7187 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7189 sched_init_granularity();
7190 free_cpumask_var(non_isolated_cpus);
7192 init_sched_rt_class();
7193 init_sched_dl_class();
7196 void __init sched_init_smp(void)
7198 sched_init_granularity();
7200 #endif /* CONFIG_SMP */
7202 int in_sched_functions(unsigned long addr)
7204 return in_lock_functions(addr) ||
7205 (addr >= (unsigned long)__sched_text_start
7206 && addr < (unsigned long)__sched_text_end);
7209 #ifdef CONFIG_CGROUP_SCHED
7211 * Default task group.
7212 * Every task in system belongs to this group at bootup.
7214 struct task_group root_task_group;
7215 LIST_HEAD(task_groups);
7217 /* Cacheline aligned slab cache for task_group */
7218 static struct kmem_cache *task_group_cache __read_mostly;
7221 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
7223 void __init sched_init(void)
7226 unsigned long alloc_size = 0, ptr;
7228 #ifdef CONFIG_FAIR_GROUP_SCHED
7229 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7231 #ifdef CONFIG_RT_GROUP_SCHED
7232 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7235 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7237 #ifdef CONFIG_FAIR_GROUP_SCHED
7238 root_task_group.se = (struct sched_entity **)ptr;
7239 ptr += nr_cpu_ids * sizeof(void **);
7241 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7242 ptr += nr_cpu_ids * sizeof(void **);
7244 #endif /* CONFIG_FAIR_GROUP_SCHED */
7245 #ifdef CONFIG_RT_GROUP_SCHED
7246 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7247 ptr += nr_cpu_ids * sizeof(void **);
7249 root_task_group.rt_rq = (struct rt_rq **)ptr;
7250 ptr += nr_cpu_ids * sizeof(void **);
7252 #endif /* CONFIG_RT_GROUP_SCHED */
7254 #ifdef CONFIG_CPUMASK_OFFSTACK
7255 for_each_possible_cpu(i) {
7256 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
7257 cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7259 #endif /* CONFIG_CPUMASK_OFFSTACK */
7261 init_rt_bandwidth(&def_rt_bandwidth,
7262 global_rt_period(), global_rt_runtime());
7263 init_dl_bandwidth(&def_dl_bandwidth,
7264 global_rt_period(), global_rt_runtime());
7267 init_defrootdomain();
7270 #ifdef CONFIG_RT_GROUP_SCHED
7271 init_rt_bandwidth(&root_task_group.rt_bandwidth,
7272 global_rt_period(), global_rt_runtime());
7273 #endif /* CONFIG_RT_GROUP_SCHED */
7275 #ifdef CONFIG_CGROUP_SCHED
7276 task_group_cache = KMEM_CACHE(task_group, 0);
7278 list_add(&root_task_group.list, &task_groups);
7279 INIT_LIST_HEAD(&root_task_group.children);
7280 INIT_LIST_HEAD(&root_task_group.siblings);
7281 autogroup_init(&init_task);
7282 #endif /* CONFIG_CGROUP_SCHED */
7284 for_each_possible_cpu(i) {
7288 raw_spin_lock_init(&rq->lock);
7290 rq->calc_load_active = 0;
7291 rq->calc_load_update = jiffies + LOAD_FREQ;
7292 init_cfs_rq(&rq->cfs);
7293 init_rt_rq(&rq->rt);
7294 init_dl_rq(&rq->dl);
7295 #ifdef CONFIG_FAIR_GROUP_SCHED
7296 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7297 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7299 * How much cpu bandwidth does root_task_group get?
7301 * In case of task-groups formed thr' the cgroup filesystem, it
7302 * gets 100% of the cpu resources in the system. This overall
7303 * system cpu resource is divided among the tasks of
7304 * root_task_group and its child task-groups in a fair manner,
7305 * based on each entity's (task or task-group's) weight
7306 * (se->load.weight).
7308 * In other words, if root_task_group has 10 tasks of weight
7309 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7310 * then A0's share of the cpu resource is:
7312 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7314 * We achieve this by letting root_task_group's tasks sit
7315 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7317 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7318 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7319 #endif /* CONFIG_FAIR_GROUP_SCHED */
7321 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7322 #ifdef CONFIG_RT_GROUP_SCHED
7323 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7326 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7327 rq->cpu_load[j] = 0;
7329 rq->last_load_update_tick = jiffies;
7334 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7335 rq->balance_callback = NULL;
7336 rq->active_balance = 0;
7337 rq->next_balance = jiffies;
7342 rq->avg_idle = 2*sysctl_sched_migration_cost;
7343 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7345 INIT_LIST_HEAD(&rq->cfs_tasks);
7347 rq_attach_root(rq, &def_root_domain);
7348 #ifdef CONFIG_NO_HZ_COMMON
7351 #ifdef CONFIG_NO_HZ_FULL
7352 rq->last_sched_tick = 0;
7356 atomic_set(&rq->nr_iowait, 0);
7359 set_load_weight(&init_task);
7361 #ifdef CONFIG_PREEMPT_NOTIFIERS
7362 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7366 * The boot idle thread does lazy MMU switching as well:
7368 atomic_inc(&init_mm.mm_count);
7369 enter_lazy_tlb(&init_mm, current);
7372 * During early bootup we pretend to be a normal task:
7374 current->sched_class = &fair_sched_class;
7377 * Make us the idle thread. Technically, schedule() should not be
7378 * called from this thread, however somewhere below it might be,
7379 * but because we are the idle thread, we just pick up running again
7380 * when this runqueue becomes "idle".
7382 init_idle(current, smp_processor_id());
7384 calc_load_update = jiffies + LOAD_FREQ;
7387 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7388 /* May be allocated at isolcpus cmdline parse time */
7389 if (cpu_isolated_map == NULL)
7390 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7391 idle_thread_set_boot_cpu();
7392 set_cpu_rq_start_time();
7394 init_sched_fair_class();
7396 scheduler_running = 1;
7399 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7400 static inline int preempt_count_equals(int preempt_offset)
7402 int nested = preempt_count() + rcu_preempt_depth();
7404 return (nested == preempt_offset);
7407 void __might_sleep(const char *file, int line, int preempt_offset)
7410 * Blocking primitives will set (and therefore destroy) current->state,
7411 * since we will exit with TASK_RUNNING make sure we enter with it,
7412 * otherwise we will destroy state.
7414 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
7415 "do not call blocking ops when !TASK_RUNNING; "
7416 "state=%lx set at [<%p>] %pS\n",
7418 (void *)current->task_state_change,
7419 (void *)current->task_state_change);
7421 ___might_sleep(file, line, preempt_offset);
7423 EXPORT_SYMBOL(__might_sleep);
7425 void ___might_sleep(const char *file, int line, int preempt_offset)
7427 static unsigned long prev_jiffy; /* ratelimiting */
7429 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7430 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7431 !is_idle_task(current)) ||
7432 system_state != SYSTEM_RUNNING || oops_in_progress)
7434 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7436 prev_jiffy = jiffies;
7439 "BUG: sleeping function called from invalid context at %s:%d\n",
7442 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7443 in_atomic(), irqs_disabled(),
7444 current->pid, current->comm);
7446 if (task_stack_end_corrupted(current))
7447 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
7449 debug_show_held_locks(current);
7450 if (irqs_disabled())
7451 print_irqtrace_events(current);
7452 #ifdef CONFIG_DEBUG_PREEMPT
7453 if (!preempt_count_equals(preempt_offset)) {
7454 pr_err("Preemption disabled at:");
7455 print_ip_sym(current->preempt_disable_ip);
7461 EXPORT_SYMBOL(___might_sleep);
7464 #ifdef CONFIG_MAGIC_SYSRQ
7465 void normalize_rt_tasks(void)
7467 struct task_struct *g, *p;
7468 struct sched_attr attr = {
7469 .sched_policy = SCHED_NORMAL,
7472 read_lock(&tasklist_lock);
7473 for_each_process_thread(g, p) {
7475 * Only normalize user tasks:
7477 if (p->flags & PF_KTHREAD)
7480 p->se.exec_start = 0;
7481 #ifdef CONFIG_SCHEDSTATS
7482 p->se.statistics.wait_start = 0;
7483 p->se.statistics.sleep_start = 0;
7484 p->se.statistics.block_start = 0;
7487 if (!dl_task(p) && !rt_task(p)) {
7489 * Renice negative nice level userspace
7492 if (task_nice(p) < 0)
7493 set_user_nice(p, 0);
7497 __sched_setscheduler(p, &attr, false, false);
7499 read_unlock(&tasklist_lock);
7502 #endif /* CONFIG_MAGIC_SYSRQ */
7504 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7506 * These functions are only useful for the IA64 MCA handling, or kdb.
7508 * They can only be called when the whole system has been
7509 * stopped - every CPU needs to be quiescent, and no scheduling
7510 * activity can take place. Using them for anything else would
7511 * be a serious bug, and as a result, they aren't even visible
7512 * under any other configuration.
7516 * curr_task - return the current task for a given cpu.
7517 * @cpu: the processor in question.
7519 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7521 * Return: The current task for @cpu.
7523 struct task_struct *curr_task(int cpu)
7525 return cpu_curr(cpu);
7528 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7532 * set_curr_task - set the current task for a given cpu.
7533 * @cpu: the processor in question.
7534 * @p: the task pointer to set.
7536 * Description: This function must only be used when non-maskable interrupts
7537 * are serviced on a separate stack. It allows the architecture to switch the
7538 * notion of the current task on a cpu in a non-blocking manner. This function
7539 * must be called with all CPU's synchronized, and interrupts disabled, the
7540 * and caller must save the original value of the current task (see
7541 * curr_task() above) and restore that value before reenabling interrupts and
7542 * re-starting the system.
7544 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7546 void set_curr_task(int cpu, struct task_struct *p)
7553 #ifdef CONFIG_CGROUP_SCHED
7554 /* task_group_lock serializes the addition/removal of task groups */
7555 static DEFINE_SPINLOCK(task_group_lock);
7557 static void free_sched_group(struct task_group *tg)
7559 free_fair_sched_group(tg);
7560 free_rt_sched_group(tg);
7562 kmem_cache_free(task_group_cache, tg);
7565 /* allocate runqueue etc for a new task group */
7566 struct task_group *sched_create_group(struct task_group *parent)
7568 struct task_group *tg;
7570 tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
7572 return ERR_PTR(-ENOMEM);
7574 if (!alloc_fair_sched_group(tg, parent))
7577 if (!alloc_rt_sched_group(tg, parent))
7583 free_sched_group(tg);
7584 return ERR_PTR(-ENOMEM);
7587 void sched_online_group(struct task_group *tg, struct task_group *parent)
7589 unsigned long flags;
7591 spin_lock_irqsave(&task_group_lock, flags);
7592 list_add_rcu(&tg->list, &task_groups);
7594 WARN_ON(!parent); /* root should already exist */
7596 tg->parent = parent;
7597 INIT_LIST_HEAD(&tg->children);
7598 list_add_rcu(&tg->siblings, &parent->children);
7599 spin_unlock_irqrestore(&task_group_lock, flags);
7602 /* rcu callback to free various structures associated with a task group */
7603 static void free_sched_group_rcu(struct rcu_head *rhp)
7605 /* now it should be safe to free those cfs_rqs */
7606 free_sched_group(container_of(rhp, struct task_group, rcu));
7609 /* Destroy runqueue etc associated with a task group */
7610 void sched_destroy_group(struct task_group *tg)
7612 /* wait for possible concurrent references to cfs_rqs complete */
7613 call_rcu(&tg->rcu, free_sched_group_rcu);
7616 void sched_offline_group(struct task_group *tg)
7618 unsigned long flags;
7620 /* end participation in shares distribution */
7621 unregister_fair_sched_group(tg);
7623 spin_lock_irqsave(&task_group_lock, flags);
7624 list_del_rcu(&tg->list);
7625 list_del_rcu(&tg->siblings);
7626 spin_unlock_irqrestore(&task_group_lock, flags);
7629 /* change task's runqueue when it moves between groups.
7630 * The caller of this function should have put the task in its new group
7631 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7632 * reflect its new group.
7634 void sched_move_task(struct task_struct *tsk)
7636 struct task_group *tg;
7637 int queued, running;
7638 unsigned long flags;
7641 rq = task_rq_lock(tsk, &flags);
7643 running = task_current(rq, tsk);
7644 queued = task_on_rq_queued(tsk);
7647 dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
7648 if (unlikely(running))
7649 put_prev_task(rq, tsk);
7652 * All callers are synchronized by task_rq_lock(); we do not use RCU
7653 * which is pointless here. Thus, we pass "true" to task_css_check()
7654 * to prevent lockdep warnings.
7656 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
7657 struct task_group, css);
7658 tg = autogroup_task_group(tsk, tg);
7659 tsk->sched_task_group = tg;
7661 #ifdef CONFIG_FAIR_GROUP_SCHED
7662 if (tsk->sched_class->task_move_group)
7663 tsk->sched_class->task_move_group(tsk);
7666 set_task_rq(tsk, task_cpu(tsk));
7668 if (unlikely(running))
7669 tsk->sched_class->set_curr_task(rq);
7671 enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
7673 task_rq_unlock(rq, tsk, &flags);
7675 #endif /* CONFIG_CGROUP_SCHED */
7677 #ifdef CONFIG_RT_GROUP_SCHED
7679 * Ensure that the real time constraints are schedulable.
7681 static DEFINE_MUTEX(rt_constraints_mutex);
7683 /* Must be called with tasklist_lock held */
7684 static inline int tg_has_rt_tasks(struct task_group *tg)
7686 struct task_struct *g, *p;
7689 * Autogroups do not have RT tasks; see autogroup_create().
7691 if (task_group_is_autogroup(tg))
7694 for_each_process_thread(g, p) {
7695 if (rt_task(p) && task_group(p) == tg)
7702 struct rt_schedulable_data {
7703 struct task_group *tg;
7708 static int tg_rt_schedulable(struct task_group *tg, void *data)
7710 struct rt_schedulable_data *d = data;
7711 struct task_group *child;
7712 unsigned long total, sum = 0;
7713 u64 period, runtime;
7715 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7716 runtime = tg->rt_bandwidth.rt_runtime;
7719 period = d->rt_period;
7720 runtime = d->rt_runtime;
7724 * Cannot have more runtime than the period.
7726 if (runtime > period && runtime != RUNTIME_INF)
7730 * Ensure we don't starve existing RT tasks.
7732 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7735 total = to_ratio(period, runtime);
7738 * Nobody can have more than the global setting allows.
7740 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7744 * The sum of our children's runtime should not exceed our own.
7746 list_for_each_entry_rcu(child, &tg->children, siblings) {
7747 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7748 runtime = child->rt_bandwidth.rt_runtime;
7750 if (child == d->tg) {
7751 period = d->rt_period;
7752 runtime = d->rt_runtime;
7755 sum += to_ratio(period, runtime);
7764 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7768 struct rt_schedulable_data data = {
7770 .rt_period = period,
7771 .rt_runtime = runtime,
7775 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7781 static int tg_set_rt_bandwidth(struct task_group *tg,
7782 u64 rt_period, u64 rt_runtime)
7787 * Disallowing the root group RT runtime is BAD, it would disallow the
7788 * kernel creating (and or operating) RT threads.
7790 if (tg == &root_task_group && rt_runtime == 0)
7793 /* No period doesn't make any sense. */
7797 mutex_lock(&rt_constraints_mutex);
7798 read_lock(&tasklist_lock);
7799 err = __rt_schedulable(tg, rt_period, rt_runtime);
7803 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7804 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7805 tg->rt_bandwidth.rt_runtime = rt_runtime;
7807 for_each_possible_cpu(i) {
7808 struct rt_rq *rt_rq = tg->rt_rq[i];
7810 raw_spin_lock(&rt_rq->rt_runtime_lock);
7811 rt_rq->rt_runtime = rt_runtime;
7812 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7814 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7816 read_unlock(&tasklist_lock);
7817 mutex_unlock(&rt_constraints_mutex);
7822 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7824 u64 rt_runtime, rt_period;
7826 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7827 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7828 if (rt_runtime_us < 0)
7829 rt_runtime = RUNTIME_INF;
7831 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7834 static long sched_group_rt_runtime(struct task_group *tg)
7838 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7841 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7842 do_div(rt_runtime_us, NSEC_PER_USEC);
7843 return rt_runtime_us;
7846 static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
7848 u64 rt_runtime, rt_period;
7850 rt_period = rt_period_us * NSEC_PER_USEC;
7851 rt_runtime = tg->rt_bandwidth.rt_runtime;
7853 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7856 static long sched_group_rt_period(struct task_group *tg)
7860 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7861 do_div(rt_period_us, NSEC_PER_USEC);
7862 return rt_period_us;
7864 #endif /* CONFIG_RT_GROUP_SCHED */
7866 #ifdef CONFIG_RT_GROUP_SCHED
7867 static int sched_rt_global_constraints(void)
7871 mutex_lock(&rt_constraints_mutex);
7872 read_lock(&tasklist_lock);
7873 ret = __rt_schedulable(NULL, 0, 0);
7874 read_unlock(&tasklist_lock);
7875 mutex_unlock(&rt_constraints_mutex);
7880 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7882 /* Don't accept realtime tasks when there is no way for them to run */
7883 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7889 #else /* !CONFIG_RT_GROUP_SCHED */
7890 static int sched_rt_global_constraints(void)
7892 unsigned long flags;
7895 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7896 for_each_possible_cpu(i) {
7897 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7899 raw_spin_lock(&rt_rq->rt_runtime_lock);
7900 rt_rq->rt_runtime = global_rt_runtime();
7901 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7903 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7907 #endif /* CONFIG_RT_GROUP_SCHED */
7909 static int sched_dl_global_validate(void)
7911 u64 runtime = global_rt_runtime();
7912 u64 period = global_rt_period();
7913 u64 new_bw = to_ratio(period, runtime);
7916 unsigned long flags;
7919 * Here we want to check the bandwidth not being set to some
7920 * value smaller than the currently allocated bandwidth in
7921 * any of the root_domains.
7923 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7924 * cycling on root_domains... Discussion on different/better
7925 * solutions is welcome!
7927 for_each_possible_cpu(cpu) {
7928 rcu_read_lock_sched();
7929 dl_b = dl_bw_of(cpu);
7931 raw_spin_lock_irqsave(&dl_b->lock, flags);
7932 if (new_bw < dl_b->total_bw)
7934 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7936 rcu_read_unlock_sched();
7945 static void sched_dl_do_global(void)
7950 unsigned long flags;
7952 def_dl_bandwidth.dl_period = global_rt_period();
7953 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7955 if (global_rt_runtime() != RUNTIME_INF)
7956 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7959 * FIXME: As above...
7961 for_each_possible_cpu(cpu) {
7962 rcu_read_lock_sched();
7963 dl_b = dl_bw_of(cpu);
7965 raw_spin_lock_irqsave(&dl_b->lock, flags);
7967 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7969 rcu_read_unlock_sched();
7973 static int sched_rt_global_validate(void)
7975 if (sysctl_sched_rt_period <= 0)
7978 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7979 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7985 static void sched_rt_do_global(void)
7987 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7988 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7991 int sched_rt_handler(struct ctl_table *table, int write,
7992 void __user *buffer, size_t *lenp,
7995 int old_period, old_runtime;
7996 static DEFINE_MUTEX(mutex);
8000 old_period = sysctl_sched_rt_period;
8001 old_runtime = sysctl_sched_rt_runtime;
8003 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8005 if (!ret && write) {
8006 ret = sched_rt_global_validate();
8010 ret = sched_dl_global_validate();
8014 ret = sched_rt_global_constraints();
8018 sched_rt_do_global();
8019 sched_dl_do_global();
8023 sysctl_sched_rt_period = old_period;
8024 sysctl_sched_rt_runtime = old_runtime;
8026 mutex_unlock(&mutex);
8031 int sched_rr_handler(struct ctl_table *table, int write,
8032 void __user *buffer, size_t *lenp,
8036 static DEFINE_MUTEX(mutex);
8039 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8040 /* make sure that internally we keep jiffies */
8041 /* also, writing zero resets timeslice to default */
8042 if (!ret && write) {
8043 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
8044 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8046 mutex_unlock(&mutex);
8050 #ifdef CONFIG_CGROUP_SCHED
8052 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8054 return css ? container_of(css, struct task_group, css) : NULL;
8057 static struct cgroup_subsys_state *
8058 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8060 struct task_group *parent = css_tg(parent_css);
8061 struct task_group *tg;
8064 /* This is early initialization for the top cgroup */
8065 return &root_task_group.css;
8068 tg = sched_create_group(parent);
8070 return ERR_PTR(-ENOMEM);
8075 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
8077 struct task_group *tg = css_tg(css);
8078 struct task_group *parent = css_tg(css->parent);
8081 sched_online_group(tg, parent);
8085 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8087 struct task_group *tg = css_tg(css);
8089 sched_destroy_group(tg);
8092 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
8094 struct task_group *tg = css_tg(css);
8096 sched_offline_group(tg);
8099 static void cpu_cgroup_fork(struct task_struct *task)
8101 sched_move_task(task);
8104 static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
8106 struct task_struct *task;
8107 struct cgroup_subsys_state *css;
8109 cgroup_taskset_for_each(task, css, tset) {
8110 #ifdef CONFIG_RT_GROUP_SCHED
8111 if (!sched_rt_can_attach(css_tg(css), task))
8114 /* We don't support RT-tasks being in separate groups */
8115 if (task->sched_class != &fair_sched_class)
8122 static void cpu_cgroup_attach(struct cgroup_taskset *tset)
8124 struct task_struct *task;
8125 struct cgroup_subsys_state *css;
8127 cgroup_taskset_for_each(task, css, tset)
8128 sched_move_task(task);
8131 #ifdef CONFIG_FAIR_GROUP_SCHED
8132 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
8133 struct cftype *cftype, u64 shareval)
8135 return sched_group_set_shares(css_tg(css), scale_load(shareval));
8138 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
8141 struct task_group *tg = css_tg(css);
8143 return (u64) scale_load_down(tg->shares);
8146 #ifdef CONFIG_CFS_BANDWIDTH
8147 static DEFINE_MUTEX(cfs_constraints_mutex);
8149 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
8150 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
8152 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
8154 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
8156 int i, ret = 0, runtime_enabled, runtime_was_enabled;
8157 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8159 if (tg == &root_task_group)
8163 * Ensure we have at some amount of bandwidth every period. This is
8164 * to prevent reaching a state of large arrears when throttled via
8165 * entity_tick() resulting in prolonged exit starvation.
8167 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
8171 * Likewise, bound things on the otherside by preventing insane quota
8172 * periods. This also allows us to normalize in computing quota
8175 if (period > max_cfs_quota_period)
8179 * Prevent race between setting of cfs_rq->runtime_enabled and
8180 * unthrottle_offline_cfs_rqs().
8183 mutex_lock(&cfs_constraints_mutex);
8184 ret = __cfs_schedulable(tg, period, quota);
8188 runtime_enabled = quota != RUNTIME_INF;
8189 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8191 * If we need to toggle cfs_bandwidth_used, off->on must occur
8192 * before making related changes, and on->off must occur afterwards
8194 if (runtime_enabled && !runtime_was_enabled)
8195 cfs_bandwidth_usage_inc();
8196 raw_spin_lock_irq(&cfs_b->lock);
8197 cfs_b->period = ns_to_ktime(period);
8198 cfs_b->quota = quota;
8200 __refill_cfs_bandwidth_runtime(cfs_b);
8201 /* restart the period timer (if active) to handle new period expiry */
8202 if (runtime_enabled)
8203 start_cfs_bandwidth(cfs_b);
8204 raw_spin_unlock_irq(&cfs_b->lock);
8206 for_each_online_cpu(i) {
8207 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8208 struct rq *rq = cfs_rq->rq;
8210 raw_spin_lock_irq(&rq->lock);
8211 cfs_rq->runtime_enabled = runtime_enabled;
8212 cfs_rq->runtime_remaining = 0;
8214 if (cfs_rq->throttled)
8215 unthrottle_cfs_rq(cfs_rq);
8216 raw_spin_unlock_irq(&rq->lock);
8218 if (runtime_was_enabled && !runtime_enabled)
8219 cfs_bandwidth_usage_dec();
8221 mutex_unlock(&cfs_constraints_mutex);
8227 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
8231 period = ktime_to_ns(tg->cfs_bandwidth.period);
8232 if (cfs_quota_us < 0)
8233 quota = RUNTIME_INF;
8235 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
8237 return tg_set_cfs_bandwidth(tg, period, quota);
8240 long tg_get_cfs_quota(struct task_group *tg)
8244 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8247 quota_us = tg->cfs_bandwidth.quota;
8248 do_div(quota_us, NSEC_PER_USEC);
8253 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
8257 period = (u64)cfs_period_us * NSEC_PER_USEC;
8258 quota = tg->cfs_bandwidth.quota;
8260 return tg_set_cfs_bandwidth(tg, period, quota);
8263 long tg_get_cfs_period(struct task_group *tg)
8267 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8268 do_div(cfs_period_us, NSEC_PER_USEC);
8270 return cfs_period_us;
8273 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
8276 return tg_get_cfs_quota(css_tg(css));
8279 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
8280 struct cftype *cftype, s64 cfs_quota_us)
8282 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8285 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
8288 return tg_get_cfs_period(css_tg(css));
8291 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
8292 struct cftype *cftype, u64 cfs_period_us)
8294 return tg_set_cfs_period(css_tg(css), cfs_period_us);
8297 struct cfs_schedulable_data {
8298 struct task_group *tg;
8303 * normalize group quota/period to be quota/max_period
8304 * note: units are usecs
8306 static u64 normalize_cfs_quota(struct task_group *tg,
8307 struct cfs_schedulable_data *d)
8315 period = tg_get_cfs_period(tg);
8316 quota = tg_get_cfs_quota(tg);
8319 /* note: these should typically be equivalent */
8320 if (quota == RUNTIME_INF || quota == -1)
8323 return to_ratio(period, quota);
8326 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8328 struct cfs_schedulable_data *d = data;
8329 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8330 s64 quota = 0, parent_quota = -1;
8333 quota = RUNTIME_INF;
8335 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8337 quota = normalize_cfs_quota(tg, d);
8338 parent_quota = parent_b->hierarchical_quota;
8341 * ensure max(child_quota) <= parent_quota, inherit when no
8344 if (quota == RUNTIME_INF)
8345 quota = parent_quota;
8346 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8349 cfs_b->hierarchical_quota = quota;
8354 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8357 struct cfs_schedulable_data data = {
8363 if (quota != RUNTIME_INF) {
8364 do_div(data.period, NSEC_PER_USEC);
8365 do_div(data.quota, NSEC_PER_USEC);
8369 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8375 static int cpu_stats_show(struct seq_file *sf, void *v)
8377 struct task_group *tg = css_tg(seq_css(sf));
8378 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8380 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8381 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8382 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8386 #endif /* CONFIG_CFS_BANDWIDTH */
8387 #endif /* CONFIG_FAIR_GROUP_SCHED */
8389 #ifdef CONFIG_RT_GROUP_SCHED
8390 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8391 struct cftype *cft, s64 val)
8393 return sched_group_set_rt_runtime(css_tg(css), val);
8396 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8399 return sched_group_rt_runtime(css_tg(css));
8402 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8403 struct cftype *cftype, u64 rt_period_us)
8405 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8408 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8411 return sched_group_rt_period(css_tg(css));
8413 #endif /* CONFIG_RT_GROUP_SCHED */
8415 static struct cftype cpu_files[] = {
8416 #ifdef CONFIG_FAIR_GROUP_SCHED
8419 .read_u64 = cpu_shares_read_u64,
8420 .write_u64 = cpu_shares_write_u64,
8423 #ifdef CONFIG_CFS_BANDWIDTH
8425 .name = "cfs_quota_us",
8426 .read_s64 = cpu_cfs_quota_read_s64,
8427 .write_s64 = cpu_cfs_quota_write_s64,
8430 .name = "cfs_period_us",
8431 .read_u64 = cpu_cfs_period_read_u64,
8432 .write_u64 = cpu_cfs_period_write_u64,
8436 .seq_show = cpu_stats_show,
8439 #ifdef CONFIG_RT_GROUP_SCHED
8441 .name = "rt_runtime_us",
8442 .read_s64 = cpu_rt_runtime_read,
8443 .write_s64 = cpu_rt_runtime_write,
8446 .name = "rt_period_us",
8447 .read_u64 = cpu_rt_period_read_uint,
8448 .write_u64 = cpu_rt_period_write_uint,
8454 struct cgroup_subsys cpu_cgrp_subsys = {
8455 .css_alloc = cpu_cgroup_css_alloc,
8456 .css_free = cpu_cgroup_css_free,
8457 .css_online = cpu_cgroup_css_online,
8458 .css_offline = cpu_cgroup_css_offline,
8459 .fork = cpu_cgroup_fork,
8460 .can_attach = cpu_cgroup_can_attach,
8461 .attach = cpu_cgroup_attach,
8462 .legacy_cftypes = cpu_files,
8466 #endif /* CONFIG_CGROUP_SCHED */
8468 void dump_cpu_task(int cpu)
8470 pr_info("Task dump for CPU %d:\n", cpu);
8471 sched_show_task(cpu_curr(cpu));
8475 * Nice levels are multiplicative, with a gentle 10% change for every
8476 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
8477 * nice 1, it will get ~10% less CPU time than another CPU-bound task
8478 * that remained on nice 0.
8480 * The "10% effect" is relative and cumulative: from _any_ nice level,
8481 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
8482 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
8483 * If a task goes up by ~10% and another task goes down by ~10% then
8484 * the relative distance between them is ~25%.)
8486 const int sched_prio_to_weight[40] = {
8487 /* -20 */ 88761, 71755, 56483, 46273, 36291,
8488 /* -15 */ 29154, 23254, 18705, 14949, 11916,
8489 /* -10 */ 9548, 7620, 6100, 4904, 3906,
8490 /* -5 */ 3121, 2501, 1991, 1586, 1277,
8491 /* 0 */ 1024, 820, 655, 526, 423,
8492 /* 5 */ 335, 272, 215, 172, 137,
8493 /* 10 */ 110, 87, 70, 56, 45,
8494 /* 15 */ 36, 29, 23, 18, 15,
8498 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
8500 * In cases where the weight does not change often, we can use the
8501 * precalculated inverse to speed up arithmetics by turning divisions
8502 * into multiplications:
8504 const u32 sched_prio_to_wmult[40] = {
8505 /* -20 */ 48388, 59856, 76040, 92818, 118348,
8506 /* -15 */ 147320, 184698, 229616, 287308, 360437,
8507 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
8508 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
8509 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
8510 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
8511 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
8512 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,