4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/debugfs.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/binfmts.h>
75 #include <linux/context_tracking.h>
76 #include <linux/compiler.h>
78 #include <asm/switch_to.h>
80 #include <asm/irq_regs.h>
81 #include <asm/mutex.h>
82 #ifdef CONFIG_PARAVIRT
83 #include <asm/paravirt.h>
87 #include "../workqueue_internal.h"
88 #include "../smpboot.h"
90 #define CREATE_TRACE_POINTS
91 #include <trace/events/sched.h>
93 #ifdef smp_mb__before_atomic
94 void __smp_mb__before_atomic(void)
96 smp_mb__before_atomic();
98 EXPORT_SYMBOL(__smp_mb__before_atomic);
101 #ifdef smp_mb__after_atomic
102 void __smp_mb__after_atomic(void)
104 smp_mb__after_atomic();
106 EXPORT_SYMBOL(__smp_mb__after_atomic);
109 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
112 ktime_t soft, hard, now;
115 if (hrtimer_active(period_timer))
118 now = hrtimer_cb_get_time(period_timer);
119 hrtimer_forward(period_timer, now, period);
121 soft = hrtimer_get_softexpires(period_timer);
122 hard = hrtimer_get_expires(period_timer);
123 delta = ktime_to_ns(ktime_sub(hard, soft));
124 __hrtimer_start_range_ns(period_timer, soft, delta,
125 HRTIMER_MODE_ABS_PINNED, 0);
129 DEFINE_MUTEX(sched_domains_mutex);
130 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
132 static void update_rq_clock_task(struct rq *rq, s64 delta);
134 void update_rq_clock(struct rq *rq)
138 if (rq->skip_clock_update > 0)
141 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
145 update_rq_clock_task(rq, delta);
149 * Debugging: various feature bits
152 #define SCHED_FEAT(name, enabled) \
153 (1UL << __SCHED_FEAT_##name) * enabled |
155 const_debug unsigned int sysctl_sched_features =
156 #include "features.h"
161 #ifdef CONFIG_SCHED_DEBUG
162 #define SCHED_FEAT(name, enabled) \
165 static const char * const sched_feat_names[] = {
166 #include "features.h"
171 static int sched_feat_show(struct seq_file *m, void *v)
175 for (i = 0; i < __SCHED_FEAT_NR; i++) {
176 if (!(sysctl_sched_features & (1UL << i)))
178 seq_printf(m, "%s ", sched_feat_names[i]);
185 #ifdef HAVE_JUMP_LABEL
187 #define jump_label_key__true STATIC_KEY_INIT_TRUE
188 #define jump_label_key__false STATIC_KEY_INIT_FALSE
190 #define SCHED_FEAT(name, enabled) \
191 jump_label_key__##enabled ,
193 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
194 #include "features.h"
199 static void sched_feat_disable(int i)
201 if (static_key_enabled(&sched_feat_keys[i]))
202 static_key_slow_dec(&sched_feat_keys[i]);
205 static void sched_feat_enable(int i)
207 if (!static_key_enabled(&sched_feat_keys[i]))
208 static_key_slow_inc(&sched_feat_keys[i]);
211 static void sched_feat_disable(int i) { };
212 static void sched_feat_enable(int i) { };
213 #endif /* HAVE_JUMP_LABEL */
215 static int sched_feat_set(char *cmp)
220 if (strncmp(cmp, "NO_", 3) == 0) {
225 for (i = 0; i < __SCHED_FEAT_NR; i++) {
226 if (strcmp(cmp, sched_feat_names[i]) == 0) {
228 sysctl_sched_features &= ~(1UL << i);
229 sched_feat_disable(i);
231 sysctl_sched_features |= (1UL << i);
232 sched_feat_enable(i);
242 sched_feat_write(struct file *filp, const char __user *ubuf,
243 size_t cnt, loff_t *ppos)
253 if (copy_from_user(&buf, ubuf, cnt))
259 /* Ensure the static_key remains in a consistent state */
260 inode = file_inode(filp);
261 mutex_lock(&inode->i_mutex);
262 i = sched_feat_set(cmp);
263 mutex_unlock(&inode->i_mutex);
264 if (i == __SCHED_FEAT_NR)
272 static int sched_feat_open(struct inode *inode, struct file *filp)
274 return single_open(filp, sched_feat_show, NULL);
277 static const struct file_operations sched_feat_fops = {
278 .open = sched_feat_open,
279 .write = sched_feat_write,
282 .release = single_release,
285 static __init int sched_init_debug(void)
287 debugfs_create_file("sched_features", 0644, NULL, NULL,
292 late_initcall(sched_init_debug);
293 #endif /* CONFIG_SCHED_DEBUG */
296 * Number of tasks to iterate in a single balance run.
297 * Limited because this is done with IRQs disabled.
299 const_debug unsigned int sysctl_sched_nr_migrate = 32;
302 * period over which we average the RT time consumption, measured
307 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
310 * period over which we measure -rt task cpu usage in us.
313 unsigned int sysctl_sched_rt_period = 1000000;
315 __read_mostly int scheduler_running;
318 * part of the period that we allow rt tasks to run in us.
321 int sysctl_sched_rt_runtime = 950000;
324 * __task_rq_lock - lock the rq @p resides on.
326 static inline struct rq *__task_rq_lock(struct task_struct *p)
331 lockdep_assert_held(&p->pi_lock);
335 raw_spin_lock(&rq->lock);
336 if (likely(rq == task_rq(p)))
338 raw_spin_unlock(&rq->lock);
343 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
345 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
346 __acquires(p->pi_lock)
352 raw_spin_lock_irqsave(&p->pi_lock, *flags);
354 raw_spin_lock(&rq->lock);
355 if (likely(rq == task_rq(p)))
357 raw_spin_unlock(&rq->lock);
358 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
362 static void __task_rq_unlock(struct rq *rq)
365 raw_spin_unlock(&rq->lock);
369 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
371 __releases(p->pi_lock)
373 raw_spin_unlock(&rq->lock);
374 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
378 * this_rq_lock - lock this runqueue and disable interrupts.
380 static struct rq *this_rq_lock(void)
387 raw_spin_lock(&rq->lock);
392 #ifdef CONFIG_SCHED_HRTICK
394 * Use HR-timers to deliver accurate preemption points.
397 static void hrtick_clear(struct rq *rq)
399 if (hrtimer_active(&rq->hrtick_timer))
400 hrtimer_cancel(&rq->hrtick_timer);
404 * High-resolution timer tick.
405 * Runs from hardirq context with interrupts disabled.
407 static enum hrtimer_restart hrtick(struct hrtimer *timer)
409 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
411 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
413 raw_spin_lock(&rq->lock);
415 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
416 raw_spin_unlock(&rq->lock);
418 return HRTIMER_NORESTART;
423 static int __hrtick_restart(struct rq *rq)
425 struct hrtimer *timer = &rq->hrtick_timer;
426 ktime_t time = hrtimer_get_softexpires(timer);
428 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
432 * called from hardirq (IPI) context
434 static void __hrtick_start(void *arg)
438 raw_spin_lock(&rq->lock);
439 __hrtick_restart(rq);
440 rq->hrtick_csd_pending = 0;
441 raw_spin_unlock(&rq->lock);
445 * Called to set the hrtick timer state.
447 * called with rq->lock held and irqs disabled
449 void hrtick_start(struct rq *rq, u64 delay)
451 struct hrtimer *timer = &rq->hrtick_timer;
452 ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
454 hrtimer_set_expires(timer, time);
456 if (rq == this_rq()) {
457 __hrtick_restart(rq);
458 } else if (!rq->hrtick_csd_pending) {
459 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
460 rq->hrtick_csd_pending = 1;
465 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
467 int cpu = (int)(long)hcpu;
470 case CPU_UP_CANCELED:
471 case CPU_UP_CANCELED_FROZEN:
472 case CPU_DOWN_PREPARE:
473 case CPU_DOWN_PREPARE_FROZEN:
475 case CPU_DEAD_FROZEN:
476 hrtick_clear(cpu_rq(cpu));
483 static __init void init_hrtick(void)
485 hotcpu_notifier(hotplug_hrtick, 0);
489 * Called to set the hrtick timer state.
491 * called with rq->lock held and irqs disabled
493 void hrtick_start(struct rq *rq, u64 delay)
495 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
496 HRTIMER_MODE_REL_PINNED, 0);
499 static inline void init_hrtick(void)
502 #endif /* CONFIG_SMP */
504 static void init_rq_hrtick(struct rq *rq)
507 rq->hrtick_csd_pending = 0;
509 rq->hrtick_csd.flags = 0;
510 rq->hrtick_csd.func = __hrtick_start;
511 rq->hrtick_csd.info = rq;
514 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
515 rq->hrtick_timer.function = hrtick;
517 #else /* CONFIG_SCHED_HRTICK */
518 static inline void hrtick_clear(struct rq *rq)
522 static inline void init_rq_hrtick(struct rq *rq)
526 static inline void init_hrtick(void)
529 #endif /* CONFIG_SCHED_HRTICK */
532 * cmpxchg based fetch_or, macro so it works for different integer types
534 #define fetch_or(ptr, val) \
535 ({ typeof(*(ptr)) __old, __val = *(ptr); \
537 __old = cmpxchg((ptr), __val, __val | (val)); \
538 if (__old == __val) \
545 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
547 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
548 * this avoids any races wrt polling state changes and thereby avoids
551 static bool set_nr_and_not_polling(struct task_struct *p)
553 struct thread_info *ti = task_thread_info(p);
554 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
558 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
560 * If this returns true, then the idle task promises to call
561 * sched_ttwu_pending() and reschedule soon.
563 static bool set_nr_if_polling(struct task_struct *p)
565 struct thread_info *ti = task_thread_info(p);
566 typeof(ti->flags) old, val = ACCESS_ONCE(ti->flags);
569 if (!(val & _TIF_POLLING_NRFLAG))
571 if (val & _TIF_NEED_RESCHED)
573 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
582 static bool set_nr_and_not_polling(struct task_struct *p)
584 set_tsk_need_resched(p);
589 static bool set_nr_if_polling(struct task_struct *p)
597 * resched_curr - mark rq's current task 'to be rescheduled now'.
599 * On UP this means the setting of the need_resched flag, on SMP it
600 * might also involve a cross-CPU call to trigger the scheduler on
603 void resched_curr(struct rq *rq)
605 struct task_struct *curr = rq->curr;
608 lockdep_assert_held(&rq->lock);
610 if (test_tsk_need_resched(curr))
615 if (cpu == smp_processor_id()) {
616 set_tsk_need_resched(curr);
617 set_preempt_need_resched();
621 if (set_nr_and_not_polling(curr))
622 smp_send_reschedule(cpu);
624 trace_sched_wake_idle_without_ipi(cpu);
627 void resched_cpu(int cpu)
629 struct rq *rq = cpu_rq(cpu);
632 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
635 raw_spin_unlock_irqrestore(&rq->lock, flags);
639 #ifdef CONFIG_NO_HZ_COMMON
641 * In the semi idle case, use the nearest busy cpu for migrating timers
642 * from an idle cpu. This is good for power-savings.
644 * We don't do similar optimization for completely idle system, as
645 * selecting an idle cpu will add more delays to the timers than intended
646 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
648 int get_nohz_timer_target(int pinned)
650 int cpu = smp_processor_id();
652 struct sched_domain *sd;
654 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
658 for_each_domain(cpu, sd) {
659 for_each_cpu(i, sched_domain_span(sd)) {
671 * When add_timer_on() enqueues a timer into the timer wheel of an
672 * idle CPU then this timer might expire before the next timer event
673 * which is scheduled to wake up that CPU. In case of a completely
674 * idle system the next event might even be infinite time into the
675 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
676 * leaves the inner idle loop so the newly added timer is taken into
677 * account when the CPU goes back to idle and evaluates the timer
678 * wheel for the next timer event.
680 static void wake_up_idle_cpu(int cpu)
682 struct rq *rq = cpu_rq(cpu);
684 if (cpu == smp_processor_id())
687 if (set_nr_and_not_polling(rq->idle))
688 smp_send_reschedule(cpu);
690 trace_sched_wake_idle_without_ipi(cpu);
693 static bool wake_up_full_nohz_cpu(int cpu)
696 * We just need the target to call irq_exit() and re-evaluate
697 * the next tick. The nohz full kick at least implies that.
698 * If needed we can still optimize that later with an
701 if (tick_nohz_full_cpu(cpu)) {
702 if (cpu != smp_processor_id() ||
703 tick_nohz_tick_stopped())
704 tick_nohz_full_kick_cpu(cpu);
711 void wake_up_nohz_cpu(int cpu)
713 if (!wake_up_full_nohz_cpu(cpu))
714 wake_up_idle_cpu(cpu);
717 static inline bool got_nohz_idle_kick(void)
719 int cpu = smp_processor_id();
721 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
724 if (idle_cpu(cpu) && !need_resched())
728 * We can't run Idle Load Balance on this CPU for this time so we
729 * cancel it and clear NOHZ_BALANCE_KICK
731 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
735 #else /* CONFIG_NO_HZ_COMMON */
737 static inline bool got_nohz_idle_kick(void)
742 #endif /* CONFIG_NO_HZ_COMMON */
744 #ifdef CONFIG_NO_HZ_FULL
745 bool sched_can_stop_tick(void)
748 * More than one running task need preemption.
749 * nr_running update is assumed to be visible
750 * after IPI is sent from wakers.
752 if (this_rq()->nr_running > 1)
757 #endif /* CONFIG_NO_HZ_FULL */
759 void sched_avg_update(struct rq *rq)
761 s64 period = sched_avg_period();
763 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
765 * Inline assembly required to prevent the compiler
766 * optimising this loop into a divmod call.
767 * See __iter_div_u64_rem() for another example of this.
769 asm("" : "+rm" (rq->age_stamp));
770 rq->age_stamp += period;
775 #endif /* CONFIG_SMP */
777 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
778 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
780 * Iterate task_group tree rooted at *from, calling @down when first entering a
781 * node and @up when leaving it for the final time.
783 * Caller must hold rcu_lock or sufficient equivalent.
785 int walk_tg_tree_from(struct task_group *from,
786 tg_visitor down, tg_visitor up, void *data)
788 struct task_group *parent, *child;
794 ret = (*down)(parent, data);
797 list_for_each_entry_rcu(child, &parent->children, siblings) {
804 ret = (*up)(parent, data);
805 if (ret || parent == from)
809 parent = parent->parent;
816 int tg_nop(struct task_group *tg, void *data)
822 static void set_load_weight(struct task_struct *p)
824 int prio = p->static_prio - MAX_RT_PRIO;
825 struct load_weight *load = &p->se.load;
828 * SCHED_IDLE tasks get minimal weight:
830 if (p->policy == SCHED_IDLE) {
831 load->weight = scale_load(WEIGHT_IDLEPRIO);
832 load->inv_weight = WMULT_IDLEPRIO;
836 load->weight = scale_load(prio_to_weight[prio]);
837 load->inv_weight = prio_to_wmult[prio];
840 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
843 sched_info_queued(rq, p);
844 p->sched_class->enqueue_task(rq, p, flags);
847 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
850 sched_info_dequeued(rq, p);
851 p->sched_class->dequeue_task(rq, p, flags);
854 void activate_task(struct rq *rq, struct task_struct *p, int flags)
856 if (task_contributes_to_load(p))
857 rq->nr_uninterruptible--;
859 enqueue_task(rq, p, flags);
862 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
864 if (task_contributes_to_load(p))
865 rq->nr_uninterruptible++;
867 dequeue_task(rq, p, flags);
870 static void update_rq_clock_task(struct rq *rq, s64 delta)
873 * In theory, the compile should just see 0 here, and optimize out the call
874 * to sched_rt_avg_update. But I don't trust it...
876 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
877 s64 steal = 0, irq_delta = 0;
879 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
880 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
883 * Since irq_time is only updated on {soft,}irq_exit, we might run into
884 * this case when a previous update_rq_clock() happened inside a
887 * When this happens, we stop ->clock_task and only update the
888 * prev_irq_time stamp to account for the part that fit, so that a next
889 * update will consume the rest. This ensures ->clock_task is
892 * It does however cause some slight miss-attribution of {soft,}irq
893 * time, a more accurate solution would be to update the irq_time using
894 * the current rq->clock timestamp, except that would require using
897 if (irq_delta > delta)
900 rq->prev_irq_time += irq_delta;
903 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
904 if (static_key_false((¶virt_steal_rq_enabled))) {
905 steal = paravirt_steal_clock(cpu_of(rq));
906 steal -= rq->prev_steal_time_rq;
908 if (unlikely(steal > delta))
911 rq->prev_steal_time_rq += steal;
916 rq->clock_task += delta;
918 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
919 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
920 sched_rt_avg_update(rq, irq_delta + steal);
924 void sched_set_stop_task(int cpu, struct task_struct *stop)
926 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
927 struct task_struct *old_stop = cpu_rq(cpu)->stop;
931 * Make it appear like a SCHED_FIFO task, its something
932 * userspace knows about and won't get confused about.
934 * Also, it will make PI more or less work without too
935 * much confusion -- but then, stop work should not
936 * rely on PI working anyway.
938 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
940 stop->sched_class = &stop_sched_class;
943 cpu_rq(cpu)->stop = stop;
947 * Reset it back to a normal scheduling class so that
948 * it can die in pieces.
950 old_stop->sched_class = &rt_sched_class;
955 * __normal_prio - return the priority that is based on the static prio
957 static inline int __normal_prio(struct task_struct *p)
959 return p->static_prio;
963 * Calculate the expected normal priority: i.e. priority
964 * without taking RT-inheritance into account. Might be
965 * boosted by interactivity modifiers. Changes upon fork,
966 * setprio syscalls, and whenever the interactivity
967 * estimator recalculates.
969 static inline int normal_prio(struct task_struct *p)
973 if (task_has_dl_policy(p))
974 prio = MAX_DL_PRIO-1;
975 else if (task_has_rt_policy(p))
976 prio = MAX_RT_PRIO-1 - p->rt_priority;
978 prio = __normal_prio(p);
983 * Calculate the current priority, i.e. the priority
984 * taken into account by the scheduler. This value might
985 * be boosted by RT tasks, or might be boosted by
986 * interactivity modifiers. Will be RT if the task got
987 * RT-boosted. If not then it returns p->normal_prio.
989 static int effective_prio(struct task_struct *p)
991 p->normal_prio = normal_prio(p);
993 * If we are RT tasks or we were boosted to RT priority,
994 * keep the priority unchanged. Otherwise, update priority
995 * to the normal priority:
997 if (!rt_prio(p->prio))
998 return p->normal_prio;
1003 * task_curr - is this task currently executing on a CPU?
1004 * @p: the task in question.
1006 * Return: 1 if the task is currently executing. 0 otherwise.
1008 inline int task_curr(const struct task_struct *p)
1010 return cpu_curr(task_cpu(p)) == p;
1013 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1014 const struct sched_class *prev_class,
1017 if (prev_class != p->sched_class) {
1018 if (prev_class->switched_from)
1019 prev_class->switched_from(rq, p);
1020 p->sched_class->switched_to(rq, p);
1021 } else if (oldprio != p->prio || dl_task(p))
1022 p->sched_class->prio_changed(rq, p, oldprio);
1025 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
1027 const struct sched_class *class;
1029 if (p->sched_class == rq->curr->sched_class) {
1030 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
1032 for_each_class(class) {
1033 if (class == rq->curr->sched_class)
1035 if (class == p->sched_class) {
1043 * A queue event has occurred, and we're going to schedule. In
1044 * this case, we can save a useless back to back clock update.
1046 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
1047 rq->skip_clock_update = 1;
1051 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1053 #ifdef CONFIG_SCHED_DEBUG
1055 * We should never call set_task_cpu() on a blocked task,
1056 * ttwu() will sort out the placement.
1058 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1059 !(task_preempt_count(p) & PREEMPT_ACTIVE));
1061 #ifdef CONFIG_LOCKDEP
1063 * The caller should hold either p->pi_lock or rq->lock, when changing
1064 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1066 * sched_move_task() holds both and thus holding either pins the cgroup,
1069 * Furthermore, all task_rq users should acquire both locks, see
1072 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1073 lockdep_is_held(&task_rq(p)->lock)));
1077 trace_sched_migrate_task(p, new_cpu);
1079 if (task_cpu(p) != new_cpu) {
1080 if (p->sched_class->migrate_task_rq)
1081 p->sched_class->migrate_task_rq(p, new_cpu);
1082 p->se.nr_migrations++;
1083 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1086 __set_task_cpu(p, new_cpu);
1089 static void __migrate_swap_task(struct task_struct *p, int cpu)
1092 struct rq *src_rq, *dst_rq;
1094 src_rq = task_rq(p);
1095 dst_rq = cpu_rq(cpu);
1097 deactivate_task(src_rq, p, 0);
1098 set_task_cpu(p, cpu);
1099 activate_task(dst_rq, p, 0);
1100 check_preempt_curr(dst_rq, p, 0);
1103 * Task isn't running anymore; make it appear like we migrated
1104 * it before it went to sleep. This means on wakeup we make the
1105 * previous cpu our targer instead of where it really is.
1111 struct migration_swap_arg {
1112 struct task_struct *src_task, *dst_task;
1113 int src_cpu, dst_cpu;
1116 static int migrate_swap_stop(void *data)
1118 struct migration_swap_arg *arg = data;
1119 struct rq *src_rq, *dst_rq;
1122 src_rq = cpu_rq(arg->src_cpu);
1123 dst_rq = cpu_rq(arg->dst_cpu);
1125 double_raw_lock(&arg->src_task->pi_lock,
1126 &arg->dst_task->pi_lock);
1127 double_rq_lock(src_rq, dst_rq);
1128 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1131 if (task_cpu(arg->src_task) != arg->src_cpu)
1134 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1137 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1140 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1141 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1146 double_rq_unlock(src_rq, dst_rq);
1147 raw_spin_unlock(&arg->dst_task->pi_lock);
1148 raw_spin_unlock(&arg->src_task->pi_lock);
1154 * Cross migrate two tasks
1156 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1158 struct migration_swap_arg arg;
1161 arg = (struct migration_swap_arg){
1163 .src_cpu = task_cpu(cur),
1165 .dst_cpu = task_cpu(p),
1168 if (arg.src_cpu == arg.dst_cpu)
1172 * These three tests are all lockless; this is OK since all of them
1173 * will be re-checked with proper locks held further down the line.
1175 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1178 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1181 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1184 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1185 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1191 struct migration_arg {
1192 struct task_struct *task;
1196 static int migration_cpu_stop(void *data);
1199 * wait_task_inactive - wait for a thread to unschedule.
1201 * If @match_state is nonzero, it's the @p->state value just checked and
1202 * not expected to change. If it changes, i.e. @p might have woken up,
1203 * then return zero. When we succeed in waiting for @p to be off its CPU,
1204 * we return a positive number (its total switch count). If a second call
1205 * a short while later returns the same number, the caller can be sure that
1206 * @p has remained unscheduled the whole time.
1208 * The caller must ensure that the task *will* unschedule sometime soon,
1209 * else this function might spin for a *long* time. This function can't
1210 * be called with interrupts off, or it may introduce deadlock with
1211 * smp_call_function() if an IPI is sent by the same process we are
1212 * waiting to become inactive.
1214 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1216 unsigned long flags;
1223 * We do the initial early heuristics without holding
1224 * any task-queue locks at all. We'll only try to get
1225 * the runqueue lock when things look like they will
1231 * If the task is actively running on another CPU
1232 * still, just relax and busy-wait without holding
1235 * NOTE! Since we don't hold any locks, it's not
1236 * even sure that "rq" stays as the right runqueue!
1237 * But we don't care, since "task_running()" will
1238 * return false if the runqueue has changed and p
1239 * is actually now running somewhere else!
1241 while (task_running(rq, p)) {
1242 if (match_state && unlikely(p->state != match_state))
1248 * Ok, time to look more closely! We need the rq
1249 * lock now, to be *sure*. If we're wrong, we'll
1250 * just go back and repeat.
1252 rq = task_rq_lock(p, &flags);
1253 trace_sched_wait_task(p);
1254 running = task_running(rq, p);
1257 if (!match_state || p->state == match_state)
1258 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1259 task_rq_unlock(rq, p, &flags);
1262 * If it changed from the expected state, bail out now.
1264 if (unlikely(!ncsw))
1268 * Was it really running after all now that we
1269 * checked with the proper locks actually held?
1271 * Oops. Go back and try again..
1273 if (unlikely(running)) {
1279 * It's not enough that it's not actively running,
1280 * it must be off the runqueue _entirely_, and not
1283 * So if it was still runnable (but just not actively
1284 * running right now), it's preempted, and we should
1285 * yield - it could be a while.
1287 if (unlikely(on_rq)) {
1288 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1290 set_current_state(TASK_UNINTERRUPTIBLE);
1291 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1296 * Ahh, all good. It wasn't running, and it wasn't
1297 * runnable, which means that it will never become
1298 * running in the future either. We're all done!
1307 * kick_process - kick a running thread to enter/exit the kernel
1308 * @p: the to-be-kicked thread
1310 * Cause a process which is running on another CPU to enter
1311 * kernel-mode, without any delay. (to get signals handled.)
1313 * NOTE: this function doesn't have to take the runqueue lock,
1314 * because all it wants to ensure is that the remote task enters
1315 * the kernel. If the IPI races and the task has been migrated
1316 * to another CPU then no harm is done and the purpose has been
1319 void kick_process(struct task_struct *p)
1325 if ((cpu != smp_processor_id()) && task_curr(p))
1326 smp_send_reschedule(cpu);
1329 EXPORT_SYMBOL_GPL(kick_process);
1330 #endif /* CONFIG_SMP */
1334 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1336 static int select_fallback_rq(int cpu, struct task_struct *p)
1338 int nid = cpu_to_node(cpu);
1339 const struct cpumask *nodemask = NULL;
1340 enum { cpuset, possible, fail } state = cpuset;
1344 * If the node that the cpu is on has been offlined, cpu_to_node()
1345 * will return -1. There is no cpu on the node, and we should
1346 * select the cpu on the other node.
1349 nodemask = cpumask_of_node(nid);
1351 /* Look for allowed, online CPU in same node. */
1352 for_each_cpu(dest_cpu, nodemask) {
1353 if (!cpu_online(dest_cpu))
1355 if (!cpu_active(dest_cpu))
1357 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1363 /* Any allowed, online CPU? */
1364 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1365 if (!cpu_online(dest_cpu))
1367 if (!cpu_active(dest_cpu))
1374 /* No more Mr. Nice Guy. */
1375 cpuset_cpus_allowed_fallback(p);
1380 do_set_cpus_allowed(p, cpu_possible_mask);
1391 if (state != cpuset) {
1393 * Don't tell them about moving exiting tasks or
1394 * kernel threads (both mm NULL), since they never
1397 if (p->mm && printk_ratelimit()) {
1398 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1399 task_pid_nr(p), p->comm, cpu);
1407 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1410 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1412 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1415 * In order not to call set_task_cpu() on a blocking task we need
1416 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1419 * Since this is common to all placement strategies, this lives here.
1421 * [ this allows ->select_task() to simply return task_cpu(p) and
1422 * not worry about this generic constraint ]
1424 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1426 cpu = select_fallback_rq(task_cpu(p), p);
1431 static void update_avg(u64 *avg, u64 sample)
1433 s64 diff = sample - *avg;
1439 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1441 #ifdef CONFIG_SCHEDSTATS
1442 struct rq *rq = this_rq();
1445 int this_cpu = smp_processor_id();
1447 if (cpu == this_cpu) {
1448 schedstat_inc(rq, ttwu_local);
1449 schedstat_inc(p, se.statistics.nr_wakeups_local);
1451 struct sched_domain *sd;
1453 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1455 for_each_domain(this_cpu, sd) {
1456 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1457 schedstat_inc(sd, ttwu_wake_remote);
1464 if (wake_flags & WF_MIGRATED)
1465 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1467 #endif /* CONFIG_SMP */
1469 schedstat_inc(rq, ttwu_count);
1470 schedstat_inc(p, se.statistics.nr_wakeups);
1472 if (wake_flags & WF_SYNC)
1473 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1475 #endif /* CONFIG_SCHEDSTATS */
1478 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1480 activate_task(rq, p, en_flags);
1483 /* if a worker is waking up, notify workqueue */
1484 if (p->flags & PF_WQ_WORKER)
1485 wq_worker_waking_up(p, cpu_of(rq));
1489 * Mark the task runnable and perform wakeup-preemption.
1492 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1494 check_preempt_curr(rq, p, wake_flags);
1495 trace_sched_wakeup(p, true);
1497 p->state = TASK_RUNNING;
1499 if (p->sched_class->task_woken)
1500 p->sched_class->task_woken(rq, p);
1502 if (rq->idle_stamp) {
1503 u64 delta = rq_clock(rq) - rq->idle_stamp;
1504 u64 max = 2*rq->max_idle_balance_cost;
1506 update_avg(&rq->avg_idle, delta);
1508 if (rq->avg_idle > max)
1517 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1520 if (p->sched_contributes_to_load)
1521 rq->nr_uninterruptible--;
1524 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1525 ttwu_do_wakeup(rq, p, wake_flags);
1529 * Called in case the task @p isn't fully descheduled from its runqueue,
1530 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1531 * since all we need to do is flip p->state to TASK_RUNNING, since
1532 * the task is still ->on_rq.
1534 static int ttwu_remote(struct task_struct *p, int wake_flags)
1539 rq = __task_rq_lock(p);
1541 /* check_preempt_curr() may use rq clock */
1542 update_rq_clock(rq);
1543 ttwu_do_wakeup(rq, p, wake_flags);
1546 __task_rq_unlock(rq);
1552 void sched_ttwu_pending(void)
1554 struct rq *rq = this_rq();
1555 struct llist_node *llist = llist_del_all(&rq->wake_list);
1556 struct task_struct *p;
1557 unsigned long flags;
1562 raw_spin_lock_irqsave(&rq->lock, flags);
1565 p = llist_entry(llist, struct task_struct, wake_entry);
1566 llist = llist_next(llist);
1567 ttwu_do_activate(rq, p, 0);
1570 raw_spin_unlock_irqrestore(&rq->lock, flags);
1573 void scheduler_ipi(void)
1576 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1577 * TIF_NEED_RESCHED remotely (for the first time) will also send
1580 preempt_fold_need_resched();
1582 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1586 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1587 * traditionally all their work was done from the interrupt return
1588 * path. Now that we actually do some work, we need to make sure
1591 * Some archs already do call them, luckily irq_enter/exit nest
1594 * Arguably we should visit all archs and update all handlers,
1595 * however a fair share of IPIs are still resched only so this would
1596 * somewhat pessimize the simple resched case.
1599 sched_ttwu_pending();
1602 * Check if someone kicked us for doing the nohz idle load balance.
1604 if (unlikely(got_nohz_idle_kick())) {
1605 this_rq()->idle_balance = 1;
1606 raise_softirq_irqoff(SCHED_SOFTIRQ);
1611 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1613 struct rq *rq = cpu_rq(cpu);
1615 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1616 if (!set_nr_if_polling(rq->idle))
1617 smp_send_reschedule(cpu);
1619 trace_sched_wake_idle_without_ipi(cpu);
1623 bool cpus_share_cache(int this_cpu, int that_cpu)
1625 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1627 #endif /* CONFIG_SMP */
1629 static void ttwu_queue(struct task_struct *p, int cpu)
1631 struct rq *rq = cpu_rq(cpu);
1633 #if defined(CONFIG_SMP)
1634 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1635 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1636 ttwu_queue_remote(p, cpu);
1641 raw_spin_lock(&rq->lock);
1642 ttwu_do_activate(rq, p, 0);
1643 raw_spin_unlock(&rq->lock);
1647 * try_to_wake_up - wake up a thread
1648 * @p: the thread to be awakened
1649 * @state: the mask of task states that can be woken
1650 * @wake_flags: wake modifier flags (WF_*)
1652 * Put it on the run-queue if it's not already there. The "current"
1653 * thread is always on the run-queue (except when the actual
1654 * re-schedule is in progress), and as such you're allowed to do
1655 * the simpler "current->state = TASK_RUNNING" to mark yourself
1656 * runnable without the overhead of this.
1658 * Return: %true if @p was woken up, %false if it was already running.
1659 * or @state didn't match @p's state.
1662 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1664 unsigned long flags;
1665 int cpu, success = 0;
1668 * If we are going to wake up a thread waiting for CONDITION we
1669 * need to ensure that CONDITION=1 done by the caller can not be
1670 * reordered with p->state check below. This pairs with mb() in
1671 * set_current_state() the waiting thread does.
1673 smp_mb__before_spinlock();
1674 raw_spin_lock_irqsave(&p->pi_lock, flags);
1675 if (!(p->state & state))
1678 success = 1; /* we're going to change ->state */
1681 if (p->on_rq && ttwu_remote(p, wake_flags))
1686 * If the owning (remote) cpu is still in the middle of schedule() with
1687 * this task as prev, wait until its done referencing the task.
1692 * Pairs with the smp_wmb() in finish_lock_switch().
1696 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1697 p->state = TASK_WAKING;
1699 if (p->sched_class->task_waking)
1700 p->sched_class->task_waking(p);
1702 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1703 if (task_cpu(p) != cpu) {
1704 wake_flags |= WF_MIGRATED;
1705 set_task_cpu(p, cpu);
1707 #endif /* CONFIG_SMP */
1711 ttwu_stat(p, cpu, wake_flags);
1713 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1719 * try_to_wake_up_local - try to wake up a local task with rq lock held
1720 * @p: the thread to be awakened
1722 * Put @p on the run-queue if it's not already there. The caller must
1723 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1726 static void try_to_wake_up_local(struct task_struct *p)
1728 struct rq *rq = task_rq(p);
1730 if (WARN_ON_ONCE(rq != this_rq()) ||
1731 WARN_ON_ONCE(p == current))
1734 lockdep_assert_held(&rq->lock);
1736 if (!raw_spin_trylock(&p->pi_lock)) {
1737 raw_spin_unlock(&rq->lock);
1738 raw_spin_lock(&p->pi_lock);
1739 raw_spin_lock(&rq->lock);
1742 if (!(p->state & TASK_NORMAL))
1746 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1748 ttwu_do_wakeup(rq, p, 0);
1749 ttwu_stat(p, smp_processor_id(), 0);
1751 raw_spin_unlock(&p->pi_lock);
1755 * wake_up_process - Wake up a specific process
1756 * @p: The process to be woken up.
1758 * Attempt to wake up the nominated process and move it to the set of runnable
1761 * Return: 1 if the process was woken up, 0 if it was already running.
1763 * It may be assumed that this function implies a write memory barrier before
1764 * changing the task state if and only if any tasks are woken up.
1766 int wake_up_process(struct task_struct *p)
1768 WARN_ON(task_is_stopped_or_traced(p));
1769 return try_to_wake_up(p, TASK_NORMAL, 0);
1771 EXPORT_SYMBOL(wake_up_process);
1773 int wake_up_state(struct task_struct *p, unsigned int state)
1775 return try_to_wake_up(p, state, 0);
1779 * Perform scheduler related setup for a newly forked process p.
1780 * p is forked by current.
1782 * __sched_fork() is basic setup used by init_idle() too:
1784 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1789 p->se.exec_start = 0;
1790 p->se.sum_exec_runtime = 0;
1791 p->se.prev_sum_exec_runtime = 0;
1792 p->se.nr_migrations = 0;
1794 INIT_LIST_HEAD(&p->se.group_node);
1796 #ifdef CONFIG_SCHEDSTATS
1797 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1800 RB_CLEAR_NODE(&p->dl.rb_node);
1801 hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1802 p->dl.dl_runtime = p->dl.runtime = 0;
1803 p->dl.dl_deadline = p->dl.deadline = 0;
1804 p->dl.dl_period = 0;
1807 INIT_LIST_HEAD(&p->rt.run_list);
1809 #ifdef CONFIG_PREEMPT_NOTIFIERS
1810 INIT_HLIST_HEAD(&p->preempt_notifiers);
1813 #ifdef CONFIG_NUMA_BALANCING
1814 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1815 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1816 p->mm->numa_scan_seq = 0;
1819 if (clone_flags & CLONE_VM)
1820 p->numa_preferred_nid = current->numa_preferred_nid;
1822 p->numa_preferred_nid = -1;
1824 p->node_stamp = 0ULL;
1825 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1826 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1827 p->numa_work.next = &p->numa_work;
1828 p->numa_faults_memory = NULL;
1829 p->numa_faults_buffer_memory = NULL;
1830 p->last_task_numa_placement = 0;
1831 p->last_sum_exec_runtime = 0;
1833 INIT_LIST_HEAD(&p->numa_entry);
1834 p->numa_group = NULL;
1835 #endif /* CONFIG_NUMA_BALANCING */
1838 #ifdef CONFIG_NUMA_BALANCING
1839 #ifdef CONFIG_SCHED_DEBUG
1840 void set_numabalancing_state(bool enabled)
1843 sched_feat_set("NUMA");
1845 sched_feat_set("NO_NUMA");
1848 __read_mostly bool numabalancing_enabled;
1850 void set_numabalancing_state(bool enabled)
1852 numabalancing_enabled = enabled;
1854 #endif /* CONFIG_SCHED_DEBUG */
1856 #ifdef CONFIG_PROC_SYSCTL
1857 int sysctl_numa_balancing(struct ctl_table *table, int write,
1858 void __user *buffer, size_t *lenp, loff_t *ppos)
1862 int state = numabalancing_enabled;
1864 if (write && !capable(CAP_SYS_ADMIN))
1869 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
1873 set_numabalancing_state(state);
1880 * fork()/clone()-time setup:
1882 int sched_fork(unsigned long clone_flags, struct task_struct *p)
1884 unsigned long flags;
1885 int cpu = get_cpu();
1887 __sched_fork(clone_flags, p);
1889 * We mark the process as running here. This guarantees that
1890 * nobody will actually run it, and a signal or other external
1891 * event cannot wake it up and insert it on the runqueue either.
1893 p->state = TASK_RUNNING;
1896 * Make sure we do not leak PI boosting priority to the child.
1898 p->prio = current->normal_prio;
1901 * Revert to default priority/policy on fork if requested.
1903 if (unlikely(p->sched_reset_on_fork)) {
1904 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
1905 p->policy = SCHED_NORMAL;
1906 p->static_prio = NICE_TO_PRIO(0);
1908 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1909 p->static_prio = NICE_TO_PRIO(0);
1911 p->prio = p->normal_prio = __normal_prio(p);
1915 * We don't need the reset flag anymore after the fork. It has
1916 * fulfilled its duty:
1918 p->sched_reset_on_fork = 0;
1921 if (dl_prio(p->prio)) {
1924 } else if (rt_prio(p->prio)) {
1925 p->sched_class = &rt_sched_class;
1927 p->sched_class = &fair_sched_class;
1930 if (p->sched_class->task_fork)
1931 p->sched_class->task_fork(p);
1934 * The child is not yet in the pid-hash so no cgroup attach races,
1935 * and the cgroup is pinned to this child due to cgroup_fork()
1936 * is ran before sched_fork().
1938 * Silence PROVE_RCU.
1940 raw_spin_lock_irqsave(&p->pi_lock, flags);
1941 set_task_cpu(p, cpu);
1942 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1944 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1945 if (likely(sched_info_on()))
1946 memset(&p->sched_info, 0, sizeof(p->sched_info));
1948 #if defined(CONFIG_SMP)
1951 init_task_preempt_count(p);
1953 plist_node_init(&p->pushable_tasks, MAX_PRIO);
1954 RB_CLEAR_NODE(&p->pushable_dl_tasks);
1961 unsigned long to_ratio(u64 period, u64 runtime)
1963 if (runtime == RUNTIME_INF)
1967 * Doing this here saves a lot of checks in all
1968 * the calling paths, and returning zero seems
1969 * safe for them anyway.
1974 return div64_u64(runtime << 20, period);
1978 inline struct dl_bw *dl_bw_of(int i)
1980 return &cpu_rq(i)->rd->dl_bw;
1983 static inline int dl_bw_cpus(int i)
1985 struct root_domain *rd = cpu_rq(i)->rd;
1988 for_each_cpu_and(i, rd->span, cpu_active_mask)
1994 inline struct dl_bw *dl_bw_of(int i)
1996 return &cpu_rq(i)->dl.dl_bw;
1999 static inline int dl_bw_cpus(int i)
2006 void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw)
2008 dl_b->total_bw -= tsk_bw;
2012 void __dl_add(struct dl_bw *dl_b, u64 tsk_bw)
2014 dl_b->total_bw += tsk_bw;
2018 bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
2020 return dl_b->bw != -1 &&
2021 dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
2025 * We must be sure that accepting a new task (or allowing changing the
2026 * parameters of an existing one) is consistent with the bandwidth
2027 * constraints. If yes, this function also accordingly updates the currently
2028 * allocated bandwidth to reflect the new situation.
2030 * This function is called while holding p's rq->lock.
2032 static int dl_overflow(struct task_struct *p, int policy,
2033 const struct sched_attr *attr)
2036 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2037 u64 period = attr->sched_period ?: attr->sched_deadline;
2038 u64 runtime = attr->sched_runtime;
2039 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2042 if (new_bw == p->dl.dl_bw)
2046 * Either if a task, enters, leave, or stays -deadline but changes
2047 * its parameters, we may need to update accordingly the total
2048 * allocated bandwidth of the container.
2050 raw_spin_lock(&dl_b->lock);
2051 cpus = dl_bw_cpus(task_cpu(p));
2052 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2053 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2054 __dl_add(dl_b, new_bw);
2056 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2057 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2058 __dl_clear(dl_b, p->dl.dl_bw);
2059 __dl_add(dl_b, new_bw);
2061 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2062 __dl_clear(dl_b, p->dl.dl_bw);
2065 raw_spin_unlock(&dl_b->lock);
2070 extern void init_dl_bw(struct dl_bw *dl_b);
2073 * wake_up_new_task - wake up a newly created task for the first time.
2075 * This function will do some initial scheduler statistics housekeeping
2076 * that must be done for every newly created context, then puts the task
2077 * on the runqueue and wakes it.
2079 void wake_up_new_task(struct task_struct *p)
2081 unsigned long flags;
2084 raw_spin_lock_irqsave(&p->pi_lock, flags);
2087 * Fork balancing, do it here and not earlier because:
2088 * - cpus_allowed can change in the fork path
2089 * - any previously selected cpu might disappear through hotplug
2091 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2094 /* Initialize new task's runnable average */
2095 init_task_runnable_average(p);
2096 rq = __task_rq_lock(p);
2097 activate_task(rq, p, 0);
2099 trace_sched_wakeup_new(p, true);
2100 check_preempt_curr(rq, p, WF_FORK);
2102 if (p->sched_class->task_woken)
2103 p->sched_class->task_woken(rq, p);
2105 task_rq_unlock(rq, p, &flags);
2108 #ifdef CONFIG_PREEMPT_NOTIFIERS
2111 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2112 * @notifier: notifier struct to register
2114 void preempt_notifier_register(struct preempt_notifier *notifier)
2116 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2118 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2121 * preempt_notifier_unregister - no longer interested in preemption notifications
2122 * @notifier: notifier struct to unregister
2124 * This is safe to call from within a preemption notifier.
2126 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2128 hlist_del(¬ifier->link);
2130 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2132 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2134 struct preempt_notifier *notifier;
2136 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2137 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2141 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2142 struct task_struct *next)
2144 struct preempt_notifier *notifier;
2146 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2147 notifier->ops->sched_out(notifier, next);
2150 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2152 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2157 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2158 struct task_struct *next)
2162 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2165 * prepare_task_switch - prepare to switch tasks
2166 * @rq: the runqueue preparing to switch
2167 * @prev: the current task that is being switched out
2168 * @next: the task we are going to switch to.
2170 * This is called with the rq lock held and interrupts off. It must
2171 * be paired with a subsequent finish_task_switch after the context
2174 * prepare_task_switch sets up locking and calls architecture specific
2178 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2179 struct task_struct *next)
2181 trace_sched_switch(prev, next);
2182 sched_info_switch(rq, prev, next);
2183 perf_event_task_sched_out(prev, next);
2184 fire_sched_out_preempt_notifiers(prev, next);
2185 prepare_lock_switch(rq, next);
2186 prepare_arch_switch(next);
2190 * finish_task_switch - clean up after a task-switch
2191 * @rq: runqueue associated with task-switch
2192 * @prev: the thread we just switched away from.
2194 * finish_task_switch must be called after the context switch, paired
2195 * with a prepare_task_switch call before the context switch.
2196 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2197 * and do any other architecture-specific cleanup actions.
2199 * Note that we may have delayed dropping an mm in context_switch(). If
2200 * so, we finish that here outside of the runqueue lock. (Doing it
2201 * with the lock held can cause deadlocks; see schedule() for
2204 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2205 __releases(rq->lock)
2207 struct mm_struct *mm = rq->prev_mm;
2213 * A task struct has one reference for the use as "current".
2214 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2215 * schedule one last time. The schedule call will never return, and
2216 * the scheduled task must drop that reference.
2217 * The test for TASK_DEAD must occur while the runqueue locks are
2218 * still held, otherwise prev could be scheduled on another cpu, die
2219 * there before we look at prev->state, and then the reference would
2221 * Manfred Spraul <manfred@colorfullife.com>
2223 prev_state = prev->state;
2224 vtime_task_switch(prev);
2225 finish_arch_switch(prev);
2226 perf_event_task_sched_in(prev, current);
2227 finish_lock_switch(rq, prev);
2228 finish_arch_post_lock_switch();
2230 fire_sched_in_preempt_notifiers(current);
2233 if (unlikely(prev_state == TASK_DEAD)) {
2234 if (prev->sched_class->task_dead)
2235 prev->sched_class->task_dead(prev);
2238 * Remove function-return probe instances associated with this
2239 * task and put them back on the free list.
2241 kprobe_flush_task(prev);
2242 put_task_struct(prev);
2245 tick_nohz_task_switch(current);
2250 /* rq->lock is NOT held, but preemption is disabled */
2251 static inline void post_schedule(struct rq *rq)
2253 if (rq->post_schedule) {
2254 unsigned long flags;
2256 raw_spin_lock_irqsave(&rq->lock, flags);
2257 if (rq->curr->sched_class->post_schedule)
2258 rq->curr->sched_class->post_schedule(rq);
2259 raw_spin_unlock_irqrestore(&rq->lock, flags);
2261 rq->post_schedule = 0;
2267 static inline void post_schedule(struct rq *rq)
2274 * schedule_tail - first thing a freshly forked thread must call.
2275 * @prev: the thread we just switched away from.
2277 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2278 __releases(rq->lock)
2280 struct rq *rq = this_rq();
2282 finish_task_switch(rq, prev);
2285 * FIXME: do we need to worry about rq being invalidated by the
2290 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2291 /* In this case, finish_task_switch does not reenable preemption */
2294 if (current->set_child_tid)
2295 put_user(task_pid_vnr(current), current->set_child_tid);
2299 * context_switch - switch to the new MM and the new
2300 * thread's register state.
2303 context_switch(struct rq *rq, struct task_struct *prev,
2304 struct task_struct *next)
2306 struct mm_struct *mm, *oldmm;
2308 prepare_task_switch(rq, prev, next);
2311 oldmm = prev->active_mm;
2313 * For paravirt, this is coupled with an exit in switch_to to
2314 * combine the page table reload and the switch backend into
2317 arch_start_context_switch(prev);
2320 next->active_mm = oldmm;
2321 atomic_inc(&oldmm->mm_count);
2322 enter_lazy_tlb(oldmm, next);
2324 switch_mm(oldmm, mm, next);
2327 prev->active_mm = NULL;
2328 rq->prev_mm = oldmm;
2331 * Since the runqueue lock will be released by the next
2332 * task (which is an invalid locking op but in the case
2333 * of the scheduler it's an obvious special-case), so we
2334 * do an early lockdep release here:
2336 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2337 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2340 context_tracking_task_switch(prev, next);
2341 /* Here we just switch the register state and the stack. */
2342 switch_to(prev, next, prev);
2346 * this_rq must be evaluated again because prev may have moved
2347 * CPUs since it called schedule(), thus the 'rq' on its stack
2348 * frame will be invalid.
2350 finish_task_switch(this_rq(), prev);
2354 * nr_running and nr_context_switches:
2356 * externally visible scheduler statistics: current number of runnable
2357 * threads, total number of context switches performed since bootup.
2359 unsigned long nr_running(void)
2361 unsigned long i, sum = 0;
2363 for_each_online_cpu(i)
2364 sum += cpu_rq(i)->nr_running;
2370 * Check if only the current task is running on the cpu.
2372 bool single_task_running(void)
2374 if (cpu_rq(smp_processor_id())->nr_running == 1)
2379 EXPORT_SYMBOL(single_task_running);
2381 unsigned long long nr_context_switches(void)
2384 unsigned long long sum = 0;
2386 for_each_possible_cpu(i)
2387 sum += cpu_rq(i)->nr_switches;
2392 unsigned long nr_iowait(void)
2394 unsigned long i, sum = 0;
2396 for_each_possible_cpu(i)
2397 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2402 unsigned long nr_iowait_cpu(int cpu)
2404 struct rq *this = cpu_rq(cpu);
2405 return atomic_read(&this->nr_iowait);
2408 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2410 struct rq *this = this_rq();
2411 *nr_waiters = atomic_read(&this->nr_iowait);
2412 *load = this->cpu_load[0];
2418 * sched_exec - execve() is a valuable balancing opportunity, because at
2419 * this point the task has the smallest effective memory and cache footprint.
2421 void sched_exec(void)
2423 struct task_struct *p = current;
2424 unsigned long flags;
2427 raw_spin_lock_irqsave(&p->pi_lock, flags);
2428 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2429 if (dest_cpu == smp_processor_id())
2432 if (likely(cpu_active(dest_cpu))) {
2433 struct migration_arg arg = { p, dest_cpu };
2435 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2436 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2440 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2445 DEFINE_PER_CPU(struct kernel_stat, kstat);
2446 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2448 EXPORT_PER_CPU_SYMBOL(kstat);
2449 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2452 * Return any ns on the sched_clock that have not yet been accounted in
2453 * @p in case that task is currently running.
2455 * Called with task_rq_lock() held on @rq.
2457 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2462 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2463 * project cycles that may never be accounted to this
2464 * thread, breaking clock_gettime().
2466 if (task_current(rq, p) && p->on_rq) {
2467 update_rq_clock(rq);
2468 ns = rq_clock_task(rq) - p->se.exec_start;
2476 unsigned long long task_delta_exec(struct task_struct *p)
2478 unsigned long flags;
2482 rq = task_rq_lock(p, &flags);
2483 ns = do_task_delta_exec(p, rq);
2484 task_rq_unlock(rq, p, &flags);
2490 * Return accounted runtime for the task.
2491 * In case the task is currently running, return the runtime plus current's
2492 * pending runtime that have not been accounted yet.
2494 unsigned long long task_sched_runtime(struct task_struct *p)
2496 unsigned long flags;
2500 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2502 * 64-bit doesn't need locks to atomically read a 64bit value.
2503 * So we have a optimization chance when the task's delta_exec is 0.
2504 * Reading ->on_cpu is racy, but this is ok.
2506 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2507 * If we race with it entering cpu, unaccounted time is 0. This is
2508 * indistinguishable from the read occurring a few cycles earlier.
2509 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2510 * been accounted, so we're correct here as well.
2512 if (!p->on_cpu || !p->on_rq)
2513 return p->se.sum_exec_runtime;
2516 rq = task_rq_lock(p, &flags);
2517 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2518 task_rq_unlock(rq, p, &flags);
2524 * This function gets called by the timer code, with HZ frequency.
2525 * We call it with interrupts disabled.
2527 void scheduler_tick(void)
2529 int cpu = smp_processor_id();
2530 struct rq *rq = cpu_rq(cpu);
2531 struct task_struct *curr = rq->curr;
2535 raw_spin_lock(&rq->lock);
2536 update_rq_clock(rq);
2537 curr->sched_class->task_tick(rq, curr, 0);
2538 update_cpu_load_active(rq);
2539 raw_spin_unlock(&rq->lock);
2541 perf_event_task_tick();
2544 rq->idle_balance = idle_cpu(cpu);
2545 trigger_load_balance(rq);
2547 rq_last_tick_reset(rq);
2550 #ifdef CONFIG_NO_HZ_FULL
2552 * scheduler_tick_max_deferment
2554 * Keep at least one tick per second when a single
2555 * active task is running because the scheduler doesn't
2556 * yet completely support full dynticks environment.
2558 * This makes sure that uptime, CFS vruntime, load
2559 * balancing, etc... continue to move forward, even
2560 * with a very low granularity.
2562 * Return: Maximum deferment in nanoseconds.
2564 u64 scheduler_tick_max_deferment(void)
2566 struct rq *rq = this_rq();
2567 unsigned long next, now = ACCESS_ONCE(jiffies);
2569 next = rq->last_sched_tick + HZ;
2571 if (time_before_eq(next, now))
2574 return jiffies_to_nsecs(next - now);
2578 notrace unsigned long get_parent_ip(unsigned long addr)
2580 if (in_lock_functions(addr)) {
2581 addr = CALLER_ADDR2;
2582 if (in_lock_functions(addr))
2583 addr = CALLER_ADDR3;
2588 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2589 defined(CONFIG_PREEMPT_TRACER))
2591 void preempt_count_add(int val)
2593 #ifdef CONFIG_DEBUG_PREEMPT
2597 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2600 __preempt_count_add(val);
2601 #ifdef CONFIG_DEBUG_PREEMPT
2603 * Spinlock count overflowing soon?
2605 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2608 if (preempt_count() == val) {
2609 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2610 #ifdef CONFIG_DEBUG_PREEMPT
2611 current->preempt_disable_ip = ip;
2613 trace_preempt_off(CALLER_ADDR0, ip);
2616 EXPORT_SYMBOL(preempt_count_add);
2617 NOKPROBE_SYMBOL(preempt_count_add);
2619 void preempt_count_sub(int val)
2621 #ifdef CONFIG_DEBUG_PREEMPT
2625 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2628 * Is the spinlock portion underflowing?
2630 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2631 !(preempt_count() & PREEMPT_MASK)))
2635 if (preempt_count() == val)
2636 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2637 __preempt_count_sub(val);
2639 EXPORT_SYMBOL(preempt_count_sub);
2640 NOKPROBE_SYMBOL(preempt_count_sub);
2645 * Print scheduling while atomic bug:
2647 static noinline void __schedule_bug(struct task_struct *prev)
2649 if (oops_in_progress)
2652 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2653 prev->comm, prev->pid, preempt_count());
2655 debug_show_held_locks(prev);
2657 if (irqs_disabled())
2658 print_irqtrace_events(prev);
2659 #ifdef CONFIG_DEBUG_PREEMPT
2660 if (in_atomic_preempt_off()) {
2661 pr_err("Preemption disabled at:");
2662 print_ip_sym(current->preempt_disable_ip);
2667 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2671 * Various schedule()-time debugging checks and statistics:
2673 static inline void schedule_debug(struct task_struct *prev)
2676 * Test if we are atomic. Since do_exit() needs to call into
2677 * schedule() atomically, we ignore that path. Otherwise whine
2678 * if we are scheduling when we should not.
2680 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
2681 __schedule_bug(prev);
2684 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2686 schedstat_inc(this_rq(), sched_count);
2690 * Pick up the highest-prio task:
2692 static inline struct task_struct *
2693 pick_next_task(struct rq *rq, struct task_struct *prev)
2695 const struct sched_class *class = &fair_sched_class;
2696 struct task_struct *p;
2699 * Optimization: we know that if all tasks are in
2700 * the fair class we can call that function directly:
2702 if (likely(prev->sched_class == class &&
2703 rq->nr_running == rq->cfs.h_nr_running)) {
2704 p = fair_sched_class.pick_next_task(rq, prev);
2705 if (unlikely(p == RETRY_TASK))
2708 /* assumes fair_sched_class->next == idle_sched_class */
2710 p = idle_sched_class.pick_next_task(rq, prev);
2716 for_each_class(class) {
2717 p = class->pick_next_task(rq, prev);
2719 if (unlikely(p == RETRY_TASK))
2725 BUG(); /* the idle class will always have a runnable task */
2729 * __schedule() is the main scheduler function.
2731 * The main means of driving the scheduler and thus entering this function are:
2733 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2735 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2736 * paths. For example, see arch/x86/entry_64.S.
2738 * To drive preemption between tasks, the scheduler sets the flag in timer
2739 * interrupt handler scheduler_tick().
2741 * 3. Wakeups don't really cause entry into schedule(). They add a
2742 * task to the run-queue and that's it.
2744 * Now, if the new task added to the run-queue preempts the current
2745 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2746 * called on the nearest possible occasion:
2748 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2750 * - in syscall or exception context, at the next outmost
2751 * preempt_enable(). (this might be as soon as the wake_up()'s
2754 * - in IRQ context, return from interrupt-handler to
2755 * preemptible context
2757 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2760 * - cond_resched() call
2761 * - explicit schedule() call
2762 * - return from syscall or exception to user-space
2763 * - return from interrupt-handler to user-space
2765 static void __sched __schedule(void)
2767 struct task_struct *prev, *next;
2768 unsigned long *switch_count;
2774 cpu = smp_processor_id();
2776 rcu_note_context_switch(cpu);
2779 schedule_debug(prev);
2781 if (sched_feat(HRTICK))
2785 * Make sure that signal_pending_state()->signal_pending() below
2786 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2787 * done by the caller to avoid the race with signal_wake_up().
2789 smp_mb__before_spinlock();
2790 raw_spin_lock_irq(&rq->lock);
2792 switch_count = &prev->nivcsw;
2793 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2794 if (unlikely(signal_pending_state(prev->state, prev))) {
2795 prev->state = TASK_RUNNING;
2797 deactivate_task(rq, prev, DEQUEUE_SLEEP);
2801 * If a worker went to sleep, notify and ask workqueue
2802 * whether it wants to wake up a task to maintain
2805 if (prev->flags & PF_WQ_WORKER) {
2806 struct task_struct *to_wakeup;
2808 to_wakeup = wq_worker_sleeping(prev, cpu);
2810 try_to_wake_up_local(to_wakeup);
2813 switch_count = &prev->nvcsw;
2816 if (prev->on_rq || rq->skip_clock_update < 0)
2817 update_rq_clock(rq);
2819 next = pick_next_task(rq, prev);
2820 clear_tsk_need_resched(prev);
2821 clear_preempt_need_resched();
2822 rq->skip_clock_update = 0;
2824 if (likely(prev != next)) {
2829 context_switch(rq, prev, next); /* unlocks the rq */
2831 * The context switch have flipped the stack from under us
2832 * and restored the local variables which were saved when
2833 * this task called schedule() in the past. prev == current
2834 * is still correct, but it can be moved to another cpu/rq.
2836 cpu = smp_processor_id();
2839 raw_spin_unlock_irq(&rq->lock);
2843 sched_preempt_enable_no_resched();
2848 static inline void sched_submit_work(struct task_struct *tsk)
2850 if (!tsk->state || tsk_is_pi_blocked(tsk))
2853 * If we are going to sleep and we have plugged IO queued,
2854 * make sure to submit it to avoid deadlocks.
2856 if (blk_needs_flush_plug(tsk))
2857 blk_schedule_flush_plug(tsk);
2860 asmlinkage __visible void __sched schedule(void)
2862 struct task_struct *tsk = current;
2864 sched_submit_work(tsk);
2867 EXPORT_SYMBOL(schedule);
2869 #ifdef CONFIG_CONTEXT_TRACKING
2870 asmlinkage __visible void __sched schedule_user(void)
2873 * If we come here after a random call to set_need_resched(),
2874 * or we have been woken up remotely but the IPI has not yet arrived,
2875 * we haven't yet exited the RCU idle mode. Do it here manually until
2876 * we find a better solution.
2885 * schedule_preempt_disabled - called with preemption disabled
2887 * Returns with preemption disabled. Note: preempt_count must be 1
2889 void __sched schedule_preempt_disabled(void)
2891 sched_preempt_enable_no_resched();
2896 #ifdef CONFIG_PREEMPT
2898 * this is the entry point to schedule() from in-kernel preemption
2899 * off of preempt_enable. Kernel preemptions off return from interrupt
2900 * occur there and call schedule directly.
2902 asmlinkage __visible void __sched notrace preempt_schedule(void)
2905 * If there is a non-zero preempt_count or interrupts are disabled,
2906 * we do not want to preempt the current task. Just return..
2908 if (likely(!preemptible()))
2912 __preempt_count_add(PREEMPT_ACTIVE);
2914 __preempt_count_sub(PREEMPT_ACTIVE);
2917 * Check again in case we missed a preemption opportunity
2918 * between schedule and now.
2921 } while (need_resched());
2923 NOKPROBE_SYMBOL(preempt_schedule);
2924 EXPORT_SYMBOL(preempt_schedule);
2925 #endif /* CONFIG_PREEMPT */
2928 * this is the entry point to schedule() from kernel preemption
2929 * off of irq context.
2930 * Note, that this is called and return with irqs disabled. This will
2931 * protect us against recursive calling from irq.
2933 asmlinkage __visible void __sched preempt_schedule_irq(void)
2935 enum ctx_state prev_state;
2937 /* Catch callers which need to be fixed */
2938 BUG_ON(preempt_count() || !irqs_disabled());
2940 prev_state = exception_enter();
2943 __preempt_count_add(PREEMPT_ACTIVE);
2946 local_irq_disable();
2947 __preempt_count_sub(PREEMPT_ACTIVE);
2950 * Check again in case we missed a preemption opportunity
2951 * between schedule and now.
2954 } while (need_resched());
2956 exception_exit(prev_state);
2959 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2962 return try_to_wake_up(curr->private, mode, wake_flags);
2964 EXPORT_SYMBOL(default_wake_function);
2966 #ifdef CONFIG_RT_MUTEXES
2969 * rt_mutex_setprio - set the current priority of a task
2971 * @prio: prio value (kernel-internal form)
2973 * This function changes the 'effective' priority of a task. It does
2974 * not touch ->normal_prio like __setscheduler().
2976 * Used by the rt_mutex code to implement priority inheritance
2977 * logic. Call site only calls if the priority of the task changed.
2979 void rt_mutex_setprio(struct task_struct *p, int prio)
2981 int oldprio, on_rq, running, enqueue_flag = 0;
2983 const struct sched_class *prev_class;
2985 BUG_ON(prio > MAX_PRIO);
2987 rq = __task_rq_lock(p);
2990 * Idle task boosting is a nono in general. There is one
2991 * exception, when PREEMPT_RT and NOHZ is active:
2993 * The idle task calls get_next_timer_interrupt() and holds
2994 * the timer wheel base->lock on the CPU and another CPU wants
2995 * to access the timer (probably to cancel it). We can safely
2996 * ignore the boosting request, as the idle CPU runs this code
2997 * with interrupts disabled and will complete the lock
2998 * protected section without being interrupted. So there is no
2999 * real need to boost.
3001 if (unlikely(p == rq->idle)) {
3002 WARN_ON(p != rq->curr);
3003 WARN_ON(p->pi_blocked_on);
3007 trace_sched_pi_setprio(p, prio);
3009 prev_class = p->sched_class;
3011 running = task_current(rq, p);
3013 dequeue_task(rq, p, 0);
3015 p->sched_class->put_prev_task(rq, p);
3018 * Boosting condition are:
3019 * 1. -rt task is running and holds mutex A
3020 * --> -dl task blocks on mutex A
3022 * 2. -dl task is running and holds mutex A
3023 * --> -dl task blocks on mutex A and could preempt the
3026 if (dl_prio(prio)) {
3027 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3028 if (!dl_prio(p->normal_prio) ||
3029 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3030 p->dl.dl_boosted = 1;
3031 p->dl.dl_throttled = 0;
3032 enqueue_flag = ENQUEUE_REPLENISH;
3034 p->dl.dl_boosted = 0;
3035 p->sched_class = &dl_sched_class;
3036 } else if (rt_prio(prio)) {
3037 if (dl_prio(oldprio))
3038 p->dl.dl_boosted = 0;
3040 enqueue_flag = ENQUEUE_HEAD;
3041 p->sched_class = &rt_sched_class;
3043 if (dl_prio(oldprio))
3044 p->dl.dl_boosted = 0;
3045 p->sched_class = &fair_sched_class;
3051 p->sched_class->set_curr_task(rq);
3053 enqueue_task(rq, p, enqueue_flag);
3055 check_class_changed(rq, p, prev_class, oldprio);
3057 __task_rq_unlock(rq);
3061 void set_user_nice(struct task_struct *p, long nice)
3063 int old_prio, delta, on_rq;
3064 unsigned long flags;
3067 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3070 * We have to be careful, if called from sys_setpriority(),
3071 * the task might be in the middle of scheduling on another CPU.
3073 rq = task_rq_lock(p, &flags);
3075 * The RT priorities are set via sched_setscheduler(), but we still
3076 * allow the 'normal' nice value to be set - but as expected
3077 * it wont have any effect on scheduling until the task is
3078 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3080 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3081 p->static_prio = NICE_TO_PRIO(nice);
3086 dequeue_task(rq, p, 0);
3088 p->static_prio = NICE_TO_PRIO(nice);
3091 p->prio = effective_prio(p);
3092 delta = p->prio - old_prio;
3095 enqueue_task(rq, p, 0);
3097 * If the task increased its priority or is running and
3098 * lowered its priority, then reschedule its CPU:
3100 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3104 task_rq_unlock(rq, p, &flags);
3106 EXPORT_SYMBOL(set_user_nice);
3109 * can_nice - check if a task can reduce its nice value
3113 int can_nice(const struct task_struct *p, const int nice)
3115 /* convert nice value [19,-20] to rlimit style value [1,40] */
3116 int nice_rlim = nice_to_rlimit(nice);
3118 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3119 capable(CAP_SYS_NICE));
3122 #ifdef __ARCH_WANT_SYS_NICE
3125 * sys_nice - change the priority of the current process.
3126 * @increment: priority increment
3128 * sys_setpriority is a more generic, but much slower function that
3129 * does similar things.
3131 SYSCALL_DEFINE1(nice, int, increment)
3136 * Setpriority might change our priority at the same moment.
3137 * We don't have to worry. Conceptually one call occurs first
3138 * and we have a single winner.
3140 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3141 nice = task_nice(current) + increment;
3143 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3144 if (increment < 0 && !can_nice(current, nice))
3147 retval = security_task_setnice(current, nice);
3151 set_user_nice(current, nice);
3158 * task_prio - return the priority value of a given task.
3159 * @p: the task in question.
3161 * Return: The priority value as seen by users in /proc.
3162 * RT tasks are offset by -200. Normal tasks are centered
3163 * around 0, value goes from -16 to +15.
3165 int task_prio(const struct task_struct *p)
3167 return p->prio - MAX_RT_PRIO;
3171 * idle_cpu - is a given cpu idle currently?
3172 * @cpu: the processor in question.
3174 * Return: 1 if the CPU is currently idle. 0 otherwise.
3176 int idle_cpu(int cpu)
3178 struct rq *rq = cpu_rq(cpu);
3180 if (rq->curr != rq->idle)
3187 if (!llist_empty(&rq->wake_list))
3195 * idle_task - return the idle task for a given cpu.
3196 * @cpu: the processor in question.
3198 * Return: The idle task for the cpu @cpu.
3200 struct task_struct *idle_task(int cpu)
3202 return cpu_rq(cpu)->idle;
3206 * find_process_by_pid - find a process with a matching PID value.
3207 * @pid: the pid in question.
3209 * The task of @pid, if found. %NULL otherwise.
3211 static struct task_struct *find_process_by_pid(pid_t pid)
3213 return pid ? find_task_by_vpid(pid) : current;
3217 * This function initializes the sched_dl_entity of a newly becoming
3218 * SCHED_DEADLINE task.
3220 * Only the static values are considered here, the actual runtime and the
3221 * absolute deadline will be properly calculated when the task is enqueued
3222 * for the first time with its new policy.
3225 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3227 struct sched_dl_entity *dl_se = &p->dl;
3229 init_dl_task_timer(dl_se);
3230 dl_se->dl_runtime = attr->sched_runtime;
3231 dl_se->dl_deadline = attr->sched_deadline;
3232 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3233 dl_se->flags = attr->sched_flags;
3234 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3235 dl_se->dl_throttled = 0;
3237 dl_se->dl_yielded = 0;
3241 * sched_setparam() passes in -1 for its policy, to let the functions
3242 * it calls know not to change it.
3244 #define SETPARAM_POLICY -1
3246 static void __setscheduler_params(struct task_struct *p,
3247 const struct sched_attr *attr)
3249 int policy = attr->sched_policy;
3251 if (policy == SETPARAM_POLICY)
3256 if (dl_policy(policy))
3257 __setparam_dl(p, attr);
3258 else if (fair_policy(policy))
3259 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3262 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3263 * !rt_policy. Always setting this ensures that things like
3264 * getparam()/getattr() don't report silly values for !rt tasks.
3266 p->rt_priority = attr->sched_priority;
3267 p->normal_prio = normal_prio(p);
3271 /* Actually do priority change: must hold pi & rq lock. */
3272 static void __setscheduler(struct rq *rq, struct task_struct *p,
3273 const struct sched_attr *attr)
3275 __setscheduler_params(p, attr);
3278 * If we get here, there was no pi waiters boosting the
3279 * task. It is safe to use the normal prio.
3281 p->prio = normal_prio(p);
3283 if (dl_prio(p->prio))
3284 p->sched_class = &dl_sched_class;
3285 else if (rt_prio(p->prio))
3286 p->sched_class = &rt_sched_class;
3288 p->sched_class = &fair_sched_class;
3292 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3294 struct sched_dl_entity *dl_se = &p->dl;
3296 attr->sched_priority = p->rt_priority;
3297 attr->sched_runtime = dl_se->dl_runtime;
3298 attr->sched_deadline = dl_se->dl_deadline;
3299 attr->sched_period = dl_se->dl_period;
3300 attr->sched_flags = dl_se->flags;
3304 * This function validates the new parameters of a -deadline task.
3305 * We ask for the deadline not being zero, and greater or equal
3306 * than the runtime, as well as the period of being zero or
3307 * greater than deadline. Furthermore, we have to be sure that
3308 * user parameters are above the internal resolution of 1us (we
3309 * check sched_runtime only since it is always the smaller one) and
3310 * below 2^63 ns (we have to check both sched_deadline and
3311 * sched_period, as the latter can be zero).
3314 __checkparam_dl(const struct sched_attr *attr)
3317 if (attr->sched_deadline == 0)
3321 * Since we truncate DL_SCALE bits, make sure we're at least
3324 if (attr->sched_runtime < (1ULL << DL_SCALE))
3328 * Since we use the MSB for wrap-around and sign issues, make
3329 * sure it's not set (mind that period can be equal to zero).
3331 if (attr->sched_deadline & (1ULL << 63) ||
3332 attr->sched_period & (1ULL << 63))
3335 /* runtime <= deadline <= period (if period != 0) */
3336 if ((attr->sched_period != 0 &&
3337 attr->sched_period < attr->sched_deadline) ||
3338 attr->sched_deadline < attr->sched_runtime)
3345 * check the target process has a UID that matches the current process's
3347 static bool check_same_owner(struct task_struct *p)
3349 const struct cred *cred = current_cred(), *pcred;
3353 pcred = __task_cred(p);
3354 match = (uid_eq(cred->euid, pcred->euid) ||
3355 uid_eq(cred->euid, pcred->uid));
3360 static int __sched_setscheduler(struct task_struct *p,
3361 const struct sched_attr *attr,
3364 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3365 MAX_RT_PRIO - 1 - attr->sched_priority;
3366 int retval, oldprio, oldpolicy = -1, on_rq, running;
3367 int policy = attr->sched_policy;
3368 unsigned long flags;
3369 const struct sched_class *prev_class;
3373 /* may grab non-irq protected spin_locks */
3374 BUG_ON(in_interrupt());
3376 /* double check policy once rq lock held */
3378 reset_on_fork = p->sched_reset_on_fork;
3379 policy = oldpolicy = p->policy;
3381 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3383 if (policy != SCHED_DEADLINE &&
3384 policy != SCHED_FIFO && policy != SCHED_RR &&
3385 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3386 policy != SCHED_IDLE)
3390 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3394 * Valid priorities for SCHED_FIFO and SCHED_RR are
3395 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3396 * SCHED_BATCH and SCHED_IDLE is 0.
3398 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3399 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3401 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3402 (rt_policy(policy) != (attr->sched_priority != 0)))
3406 * Allow unprivileged RT tasks to decrease priority:
3408 if (user && !capable(CAP_SYS_NICE)) {
3409 if (fair_policy(policy)) {
3410 if (attr->sched_nice < task_nice(p) &&
3411 !can_nice(p, attr->sched_nice))
3415 if (rt_policy(policy)) {
3416 unsigned long rlim_rtprio =
3417 task_rlimit(p, RLIMIT_RTPRIO);
3419 /* can't set/change the rt policy */
3420 if (policy != p->policy && !rlim_rtprio)
3423 /* can't increase priority */
3424 if (attr->sched_priority > p->rt_priority &&
3425 attr->sched_priority > rlim_rtprio)
3430 * Can't set/change SCHED_DEADLINE policy at all for now
3431 * (safest behavior); in the future we would like to allow
3432 * unprivileged DL tasks to increase their relative deadline
3433 * or reduce their runtime (both ways reducing utilization)
3435 if (dl_policy(policy))
3439 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3440 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3442 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3443 if (!can_nice(p, task_nice(p)))
3447 /* can't change other user's priorities */
3448 if (!check_same_owner(p))
3451 /* Normal users shall not reset the sched_reset_on_fork flag */
3452 if (p->sched_reset_on_fork && !reset_on_fork)
3457 retval = security_task_setscheduler(p);
3463 * make sure no PI-waiters arrive (or leave) while we are
3464 * changing the priority of the task:
3466 * To be able to change p->policy safely, the appropriate
3467 * runqueue lock must be held.
3469 rq = task_rq_lock(p, &flags);
3472 * Changing the policy of the stop threads its a very bad idea
3474 if (p == rq->stop) {
3475 task_rq_unlock(rq, p, &flags);
3480 * If not changing anything there's no need to proceed further,
3481 * but store a possible modification of reset_on_fork.
3483 if (unlikely(policy == p->policy)) {
3484 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3486 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3488 if (dl_policy(policy))
3491 p->sched_reset_on_fork = reset_on_fork;
3492 task_rq_unlock(rq, p, &flags);
3498 #ifdef CONFIG_RT_GROUP_SCHED
3500 * Do not allow realtime tasks into groups that have no runtime
3503 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3504 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3505 !task_group_is_autogroup(task_group(p))) {
3506 task_rq_unlock(rq, p, &flags);
3511 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3512 cpumask_t *span = rq->rd->span;
3515 * Don't allow tasks with an affinity mask smaller than
3516 * the entire root_domain to become SCHED_DEADLINE. We
3517 * will also fail if there's no bandwidth available.
3519 if (!cpumask_subset(span, &p->cpus_allowed) ||
3520 rq->rd->dl_bw.bw == 0) {
3521 task_rq_unlock(rq, p, &flags);
3528 /* recheck policy now with rq lock held */
3529 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3530 policy = oldpolicy = -1;
3531 task_rq_unlock(rq, p, &flags);
3536 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3537 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3540 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3541 task_rq_unlock(rq, p, &flags);
3545 p->sched_reset_on_fork = reset_on_fork;
3549 * Special case for priority boosted tasks.
3551 * If the new priority is lower or equal (user space view)
3552 * than the current (boosted) priority, we just store the new
3553 * normal parameters and do not touch the scheduler class and
3554 * the runqueue. This will be done when the task deboost
3557 if (rt_mutex_check_prio(p, newprio)) {
3558 __setscheduler_params(p, attr);
3559 task_rq_unlock(rq, p, &flags);
3564 running = task_current(rq, p);
3566 dequeue_task(rq, p, 0);
3568 p->sched_class->put_prev_task(rq, p);
3570 prev_class = p->sched_class;
3571 __setscheduler(rq, p, attr);
3574 p->sched_class->set_curr_task(rq);
3577 * We enqueue to tail when the priority of a task is
3578 * increased (user space view).
3580 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
3583 check_class_changed(rq, p, prev_class, oldprio);
3584 task_rq_unlock(rq, p, &flags);
3586 rt_mutex_adjust_pi(p);
3591 static int _sched_setscheduler(struct task_struct *p, int policy,
3592 const struct sched_param *param, bool check)
3594 struct sched_attr attr = {
3595 .sched_policy = policy,
3596 .sched_priority = param->sched_priority,
3597 .sched_nice = PRIO_TO_NICE(p->static_prio),
3600 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
3601 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
3602 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3603 policy &= ~SCHED_RESET_ON_FORK;
3604 attr.sched_policy = policy;
3607 return __sched_setscheduler(p, &attr, check);
3610 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3611 * @p: the task in question.
3612 * @policy: new policy.
3613 * @param: structure containing the new RT priority.
3615 * Return: 0 on success. An error code otherwise.
3617 * NOTE that the task may be already dead.
3619 int sched_setscheduler(struct task_struct *p, int policy,
3620 const struct sched_param *param)
3622 return _sched_setscheduler(p, policy, param, true);
3624 EXPORT_SYMBOL_GPL(sched_setscheduler);
3626 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
3628 return __sched_setscheduler(p, attr, true);
3630 EXPORT_SYMBOL_GPL(sched_setattr);
3633 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3634 * @p: the task in question.
3635 * @policy: new policy.
3636 * @param: structure containing the new RT priority.
3638 * Just like sched_setscheduler, only don't bother checking if the
3639 * current context has permission. For example, this is needed in
3640 * stop_machine(): we create temporary high priority worker threads,
3641 * but our caller might not have that capability.
3643 * Return: 0 on success. An error code otherwise.
3645 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3646 const struct sched_param *param)
3648 return _sched_setscheduler(p, policy, param, false);
3652 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3654 struct sched_param lparam;
3655 struct task_struct *p;
3658 if (!param || pid < 0)
3660 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3665 p = find_process_by_pid(pid);
3667 retval = sched_setscheduler(p, policy, &lparam);
3674 * Mimics kernel/events/core.c perf_copy_attr().
3676 static int sched_copy_attr(struct sched_attr __user *uattr,
3677 struct sched_attr *attr)
3682 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
3686 * zero the full structure, so that a short copy will be nice.
3688 memset(attr, 0, sizeof(*attr));
3690 ret = get_user(size, &uattr->size);
3694 if (size > PAGE_SIZE) /* silly large */
3697 if (!size) /* abi compat */
3698 size = SCHED_ATTR_SIZE_VER0;
3700 if (size < SCHED_ATTR_SIZE_VER0)
3704 * If we're handed a bigger struct than we know of,
3705 * ensure all the unknown bits are 0 - i.e. new
3706 * user-space does not rely on any kernel feature
3707 * extensions we dont know about yet.
3709 if (size > sizeof(*attr)) {
3710 unsigned char __user *addr;
3711 unsigned char __user *end;
3714 addr = (void __user *)uattr + sizeof(*attr);
3715 end = (void __user *)uattr + size;
3717 for (; addr < end; addr++) {
3718 ret = get_user(val, addr);
3724 size = sizeof(*attr);
3727 ret = copy_from_user(attr, uattr, size);
3732 * XXX: do we want to be lenient like existing syscalls; or do we want
3733 * to be strict and return an error on out-of-bounds values?
3735 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
3740 put_user(sizeof(*attr), &uattr->size);
3745 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3746 * @pid: the pid in question.
3747 * @policy: new policy.
3748 * @param: structure containing the new RT priority.
3750 * Return: 0 on success. An error code otherwise.
3752 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3753 struct sched_param __user *, param)
3755 /* negative values for policy are not valid */
3759 return do_sched_setscheduler(pid, policy, param);
3763 * sys_sched_setparam - set/change the RT priority of a thread
3764 * @pid: the pid in question.
3765 * @param: structure containing the new RT priority.
3767 * Return: 0 on success. An error code otherwise.
3769 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3771 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
3775 * sys_sched_setattr - same as above, but with extended sched_attr
3776 * @pid: the pid in question.
3777 * @uattr: structure containing the extended parameters.
3778 * @flags: for future extension.
3780 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
3781 unsigned int, flags)
3783 struct sched_attr attr;
3784 struct task_struct *p;
3787 if (!uattr || pid < 0 || flags)
3790 retval = sched_copy_attr(uattr, &attr);
3794 if ((int)attr.sched_policy < 0)
3799 p = find_process_by_pid(pid);
3801 retval = sched_setattr(p, &attr);
3808 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3809 * @pid: the pid in question.
3811 * Return: On success, the policy of the thread. Otherwise, a negative error
3814 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3816 struct task_struct *p;
3824 p = find_process_by_pid(pid);
3826 retval = security_task_getscheduler(p);
3829 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3836 * sys_sched_getparam - get the RT priority of a thread
3837 * @pid: the pid in question.
3838 * @param: structure containing the RT priority.
3840 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3843 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3845 struct sched_param lp = { .sched_priority = 0 };
3846 struct task_struct *p;
3849 if (!param || pid < 0)
3853 p = find_process_by_pid(pid);
3858 retval = security_task_getscheduler(p);
3862 if (task_has_rt_policy(p))
3863 lp.sched_priority = p->rt_priority;
3867 * This one might sleep, we cannot do it with a spinlock held ...
3869 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3878 static int sched_read_attr(struct sched_attr __user *uattr,
3879 struct sched_attr *attr,
3884 if (!access_ok(VERIFY_WRITE, uattr, usize))
3888 * If we're handed a smaller struct than we know of,
3889 * ensure all the unknown bits are 0 - i.e. old
3890 * user-space does not get uncomplete information.
3892 if (usize < sizeof(*attr)) {
3893 unsigned char *addr;
3896 addr = (void *)attr + usize;
3897 end = (void *)attr + sizeof(*attr);
3899 for (; addr < end; addr++) {
3907 ret = copy_to_user(uattr, attr, attr->size);
3915 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3916 * @pid: the pid in question.
3917 * @uattr: structure containing the extended parameters.
3918 * @size: sizeof(attr) for fwd/bwd comp.
3919 * @flags: for future extension.
3921 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
3922 unsigned int, size, unsigned int, flags)
3924 struct sched_attr attr = {
3925 .size = sizeof(struct sched_attr),
3927 struct task_struct *p;
3930 if (!uattr || pid < 0 || size > PAGE_SIZE ||
3931 size < SCHED_ATTR_SIZE_VER0 || flags)
3935 p = find_process_by_pid(pid);
3940 retval = security_task_getscheduler(p);
3944 attr.sched_policy = p->policy;
3945 if (p->sched_reset_on_fork)
3946 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3947 if (task_has_dl_policy(p))
3948 __getparam_dl(p, &attr);
3949 else if (task_has_rt_policy(p))
3950 attr.sched_priority = p->rt_priority;
3952 attr.sched_nice = task_nice(p);
3956 retval = sched_read_attr(uattr, &attr, size);
3964 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3966 cpumask_var_t cpus_allowed, new_mask;
3967 struct task_struct *p;
3972 p = find_process_by_pid(pid);
3978 /* Prevent p going away */
3982 if (p->flags & PF_NO_SETAFFINITY) {
3986 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
3990 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
3992 goto out_free_cpus_allowed;
3995 if (!check_same_owner(p)) {
3997 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4004 retval = security_task_setscheduler(p);
4009 cpuset_cpus_allowed(p, cpus_allowed);
4010 cpumask_and(new_mask, in_mask, cpus_allowed);
4013 * Since bandwidth control happens on root_domain basis,
4014 * if admission test is enabled, we only admit -deadline
4015 * tasks allowed to run on all the CPUs in the task's
4019 if (task_has_dl_policy(p)) {
4020 const struct cpumask *span = task_rq(p)->rd->span;
4022 if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {
4029 retval = set_cpus_allowed_ptr(p, new_mask);
4032 cpuset_cpus_allowed(p, cpus_allowed);
4033 if (!cpumask_subset(new_mask, cpus_allowed)) {
4035 * We must have raced with a concurrent cpuset
4036 * update. Just reset the cpus_allowed to the
4037 * cpuset's cpus_allowed
4039 cpumask_copy(new_mask, cpus_allowed);
4044 free_cpumask_var(new_mask);
4045 out_free_cpus_allowed:
4046 free_cpumask_var(cpus_allowed);
4052 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4053 struct cpumask *new_mask)
4055 if (len < cpumask_size())
4056 cpumask_clear(new_mask);
4057 else if (len > cpumask_size())
4058 len = cpumask_size();
4060 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4064 * sys_sched_setaffinity - set the cpu affinity of a process
4065 * @pid: pid of the process
4066 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4067 * @user_mask_ptr: user-space pointer to the new cpu mask
4069 * Return: 0 on success. An error code otherwise.
4071 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4072 unsigned long __user *, user_mask_ptr)
4074 cpumask_var_t new_mask;
4077 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4080 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4082 retval = sched_setaffinity(pid, new_mask);
4083 free_cpumask_var(new_mask);
4087 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4089 struct task_struct *p;
4090 unsigned long flags;
4096 p = find_process_by_pid(pid);
4100 retval = security_task_getscheduler(p);
4104 raw_spin_lock_irqsave(&p->pi_lock, flags);
4105 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4106 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4115 * sys_sched_getaffinity - get the cpu affinity of a process
4116 * @pid: pid of the process
4117 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4118 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4120 * Return: 0 on success. An error code otherwise.
4122 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4123 unsigned long __user *, user_mask_ptr)
4128 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4130 if (len & (sizeof(unsigned long)-1))
4133 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4136 ret = sched_getaffinity(pid, mask);
4138 size_t retlen = min_t(size_t, len, cpumask_size());
4140 if (copy_to_user(user_mask_ptr, mask, retlen))
4145 free_cpumask_var(mask);
4151 * sys_sched_yield - yield the current processor to other threads.
4153 * This function yields the current CPU to other tasks. If there are no
4154 * other threads running on this CPU then this function will return.
4158 SYSCALL_DEFINE0(sched_yield)
4160 struct rq *rq = this_rq_lock();
4162 schedstat_inc(rq, yld_count);
4163 current->sched_class->yield_task(rq);
4166 * Since we are going to call schedule() anyway, there's
4167 * no need to preempt or enable interrupts:
4169 __release(rq->lock);
4170 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4171 do_raw_spin_unlock(&rq->lock);
4172 sched_preempt_enable_no_resched();
4179 static void __cond_resched(void)
4181 __preempt_count_add(PREEMPT_ACTIVE);
4183 __preempt_count_sub(PREEMPT_ACTIVE);
4186 int __sched _cond_resched(void)
4188 if (should_resched()) {
4194 EXPORT_SYMBOL(_cond_resched);
4197 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4198 * call schedule, and on return reacquire the lock.
4200 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4201 * operations here to prevent schedule() from being called twice (once via
4202 * spin_unlock(), once by hand).
4204 int __cond_resched_lock(spinlock_t *lock)
4206 int resched = should_resched();
4209 lockdep_assert_held(lock);
4211 if (spin_needbreak(lock) || resched) {
4222 EXPORT_SYMBOL(__cond_resched_lock);
4224 int __sched __cond_resched_softirq(void)
4226 BUG_ON(!in_softirq());
4228 if (should_resched()) {
4236 EXPORT_SYMBOL(__cond_resched_softirq);
4239 * yield - yield the current processor to other threads.
4241 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4243 * The scheduler is at all times free to pick the calling task as the most
4244 * eligible task to run, if removing the yield() call from your code breaks
4245 * it, its already broken.
4247 * Typical broken usage is:
4252 * where one assumes that yield() will let 'the other' process run that will
4253 * make event true. If the current task is a SCHED_FIFO task that will never
4254 * happen. Never use yield() as a progress guarantee!!
4256 * If you want to use yield() to wait for something, use wait_event().
4257 * If you want to use yield() to be 'nice' for others, use cond_resched().
4258 * If you still want to use yield(), do not!
4260 void __sched yield(void)
4262 set_current_state(TASK_RUNNING);
4265 EXPORT_SYMBOL(yield);
4268 * yield_to - yield the current processor to another thread in
4269 * your thread group, or accelerate that thread toward the
4270 * processor it's on.
4272 * @preempt: whether task preemption is allowed or not
4274 * It's the caller's job to ensure that the target task struct
4275 * can't go away on us before we can do any checks.
4278 * true (>0) if we indeed boosted the target task.
4279 * false (0) if we failed to boost the target.
4280 * -ESRCH if there's no task to yield to.
4282 int __sched yield_to(struct task_struct *p, bool preempt)
4284 struct task_struct *curr = current;
4285 struct rq *rq, *p_rq;
4286 unsigned long flags;
4289 local_irq_save(flags);
4295 * If we're the only runnable task on the rq and target rq also
4296 * has only one task, there's absolutely no point in yielding.
4298 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4303 double_rq_lock(rq, p_rq);
4304 if (task_rq(p) != p_rq) {
4305 double_rq_unlock(rq, p_rq);
4309 if (!curr->sched_class->yield_to_task)
4312 if (curr->sched_class != p->sched_class)
4315 if (task_running(p_rq, p) || p->state)
4318 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4320 schedstat_inc(rq, yld_count);
4322 * Make p's CPU reschedule; pick_next_entity takes care of
4325 if (preempt && rq != p_rq)
4330 double_rq_unlock(rq, p_rq);
4332 local_irq_restore(flags);
4339 EXPORT_SYMBOL_GPL(yield_to);
4342 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4343 * that process accounting knows that this is a task in IO wait state.
4345 void __sched io_schedule(void)
4347 struct rq *rq = raw_rq();
4349 delayacct_blkio_start();
4350 atomic_inc(&rq->nr_iowait);
4351 blk_flush_plug(current);
4352 current->in_iowait = 1;
4354 current->in_iowait = 0;
4355 atomic_dec(&rq->nr_iowait);
4356 delayacct_blkio_end();
4358 EXPORT_SYMBOL(io_schedule);
4360 long __sched io_schedule_timeout(long timeout)
4362 struct rq *rq = raw_rq();
4365 delayacct_blkio_start();
4366 atomic_inc(&rq->nr_iowait);
4367 blk_flush_plug(current);
4368 current->in_iowait = 1;
4369 ret = schedule_timeout(timeout);
4370 current->in_iowait = 0;
4371 atomic_dec(&rq->nr_iowait);
4372 delayacct_blkio_end();
4377 * sys_sched_get_priority_max - return maximum RT priority.
4378 * @policy: scheduling class.
4380 * Return: On success, this syscall returns the maximum
4381 * rt_priority that can be used by a given scheduling class.
4382 * On failure, a negative error code is returned.
4384 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4391 ret = MAX_USER_RT_PRIO-1;
4393 case SCHED_DEADLINE:
4404 * sys_sched_get_priority_min - return minimum RT priority.
4405 * @policy: scheduling class.
4407 * Return: On success, this syscall returns the minimum
4408 * rt_priority that can be used by a given scheduling class.
4409 * On failure, a negative error code is returned.
4411 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4420 case SCHED_DEADLINE:
4430 * sys_sched_rr_get_interval - return the default timeslice of a process.
4431 * @pid: pid of the process.
4432 * @interval: userspace pointer to the timeslice value.
4434 * this syscall writes the default timeslice value of a given process
4435 * into the user-space timespec buffer. A value of '0' means infinity.
4437 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4440 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4441 struct timespec __user *, interval)
4443 struct task_struct *p;
4444 unsigned int time_slice;
4445 unsigned long flags;
4455 p = find_process_by_pid(pid);
4459 retval = security_task_getscheduler(p);
4463 rq = task_rq_lock(p, &flags);
4465 if (p->sched_class->get_rr_interval)
4466 time_slice = p->sched_class->get_rr_interval(rq, p);
4467 task_rq_unlock(rq, p, &flags);
4470 jiffies_to_timespec(time_slice, &t);
4471 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4479 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4481 void sched_show_task(struct task_struct *p)
4483 unsigned long free = 0;
4487 state = p->state ? __ffs(p->state) + 1 : 0;
4488 printk(KERN_INFO "%-15.15s %c", p->comm,
4489 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4490 #if BITS_PER_LONG == 32
4491 if (state == TASK_RUNNING)
4492 printk(KERN_CONT " running ");
4494 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4496 if (state == TASK_RUNNING)
4497 printk(KERN_CONT " running task ");
4499 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4501 #ifdef CONFIG_DEBUG_STACK_USAGE
4502 free = stack_not_used(p);
4505 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4507 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4508 task_pid_nr(p), ppid,
4509 (unsigned long)task_thread_info(p)->flags);
4511 print_worker_info(KERN_INFO, p);
4512 show_stack(p, NULL);
4515 void show_state_filter(unsigned long state_filter)
4517 struct task_struct *g, *p;
4519 #if BITS_PER_LONG == 32
4521 " task PC stack pid father\n");
4524 " task PC stack pid father\n");
4527 do_each_thread(g, p) {
4529 * reset the NMI-timeout, listing all files on a slow
4530 * console might take a lot of time:
4532 touch_nmi_watchdog();
4533 if (!state_filter || (p->state & state_filter))
4535 } while_each_thread(g, p);
4537 touch_all_softlockup_watchdogs();
4539 #ifdef CONFIG_SCHED_DEBUG
4540 sysrq_sched_debug_show();
4544 * Only show locks if all tasks are dumped:
4547 debug_show_all_locks();
4550 void init_idle_bootup_task(struct task_struct *idle)
4552 idle->sched_class = &idle_sched_class;
4556 * init_idle - set up an idle thread for a given CPU
4557 * @idle: task in question
4558 * @cpu: cpu the idle task belongs to
4560 * NOTE: this function does not set the idle thread's NEED_RESCHED
4561 * flag, to make booting more robust.
4563 void init_idle(struct task_struct *idle, int cpu)
4565 struct rq *rq = cpu_rq(cpu);
4566 unsigned long flags;
4568 raw_spin_lock_irqsave(&rq->lock, flags);
4570 __sched_fork(0, idle);
4571 idle->state = TASK_RUNNING;
4572 idle->se.exec_start = sched_clock();
4574 do_set_cpus_allowed(idle, cpumask_of(cpu));
4576 * We're having a chicken and egg problem, even though we are
4577 * holding rq->lock, the cpu isn't yet set to this cpu so the
4578 * lockdep check in task_group() will fail.
4580 * Similar case to sched_fork(). / Alternatively we could
4581 * use task_rq_lock() here and obtain the other rq->lock.
4586 __set_task_cpu(idle, cpu);
4589 rq->curr = rq->idle = idle;
4591 #if defined(CONFIG_SMP)
4594 raw_spin_unlock_irqrestore(&rq->lock, flags);
4596 /* Set the preempt count _outside_ the spinlocks! */
4597 init_idle_preempt_count(idle, cpu);
4600 * The idle tasks have their own, simple scheduling class:
4602 idle->sched_class = &idle_sched_class;
4603 ftrace_graph_init_idle_task(idle, cpu);
4604 vtime_init_idle(idle, cpu);
4605 #if defined(CONFIG_SMP)
4606 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4611 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4613 if (p->sched_class && p->sched_class->set_cpus_allowed)
4614 p->sched_class->set_cpus_allowed(p, new_mask);
4616 cpumask_copy(&p->cpus_allowed, new_mask);
4617 p->nr_cpus_allowed = cpumask_weight(new_mask);
4621 * This is how migration works:
4623 * 1) we invoke migration_cpu_stop() on the target CPU using
4625 * 2) stopper starts to run (implicitly forcing the migrated thread
4627 * 3) it checks whether the migrated task is still in the wrong runqueue.
4628 * 4) if it's in the wrong runqueue then the migration thread removes
4629 * it and puts it into the right queue.
4630 * 5) stopper completes and stop_one_cpu() returns and the migration
4635 * Change a given task's CPU affinity. Migrate the thread to a
4636 * proper CPU and schedule it away if the CPU it's executing on
4637 * is removed from the allowed bitmask.
4639 * NOTE: the caller must have a valid reference to the task, the
4640 * task must not exit() & deallocate itself prematurely. The
4641 * call is not atomic; no spinlocks may be held.
4643 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4645 unsigned long flags;
4647 unsigned int dest_cpu;
4650 rq = task_rq_lock(p, &flags);
4652 if (cpumask_equal(&p->cpus_allowed, new_mask))
4655 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4660 do_set_cpus_allowed(p, new_mask);
4662 /* Can the task run on the task's current CPU? If so, we're done */
4663 if (cpumask_test_cpu(task_cpu(p), new_mask))
4666 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4668 struct migration_arg arg = { p, dest_cpu };
4669 /* Need help from migration thread: drop lock and wait. */
4670 task_rq_unlock(rq, p, &flags);
4671 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4672 tlb_migrate_finish(p->mm);
4676 task_rq_unlock(rq, p, &flags);
4680 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4683 * Move (not current) task off this cpu, onto dest cpu. We're doing
4684 * this because either it can't run here any more (set_cpus_allowed()
4685 * away from this CPU, or CPU going down), or because we're
4686 * attempting to rebalance this task on exec (sched_exec).
4688 * So we race with normal scheduler movements, but that's OK, as long
4689 * as the task is no longer on this CPU.
4691 * Returns non-zero if task was successfully migrated.
4693 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4695 struct rq *rq_dest, *rq_src;
4698 if (unlikely(!cpu_active(dest_cpu)))
4701 rq_src = cpu_rq(src_cpu);
4702 rq_dest = cpu_rq(dest_cpu);
4704 raw_spin_lock(&p->pi_lock);
4705 double_rq_lock(rq_src, rq_dest);
4706 /* Already moved. */
4707 if (task_cpu(p) != src_cpu)
4709 /* Affinity changed (again). */
4710 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4714 * If we're not on a rq, the next wake-up will ensure we're
4718 dequeue_task(rq_src, p, 0);
4719 set_task_cpu(p, dest_cpu);
4720 enqueue_task(rq_dest, p, 0);
4721 check_preempt_curr(rq_dest, p, 0);
4726 double_rq_unlock(rq_src, rq_dest);
4727 raw_spin_unlock(&p->pi_lock);
4731 #ifdef CONFIG_NUMA_BALANCING
4732 /* Migrate current task p to target_cpu */
4733 int migrate_task_to(struct task_struct *p, int target_cpu)
4735 struct migration_arg arg = { p, target_cpu };
4736 int curr_cpu = task_cpu(p);
4738 if (curr_cpu == target_cpu)
4741 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4744 /* TODO: This is not properly updating schedstats */
4746 trace_sched_move_numa(p, curr_cpu, target_cpu);
4747 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4751 * Requeue a task on a given node and accurately track the number of NUMA
4752 * tasks on the runqueues
4754 void sched_setnuma(struct task_struct *p, int nid)
4757 unsigned long flags;
4758 bool on_rq, running;
4760 rq = task_rq_lock(p, &flags);
4762 running = task_current(rq, p);
4765 dequeue_task(rq, p, 0);
4767 p->sched_class->put_prev_task(rq, p);
4769 p->numa_preferred_nid = nid;
4772 p->sched_class->set_curr_task(rq);
4774 enqueue_task(rq, p, 0);
4775 task_rq_unlock(rq, p, &flags);
4780 * migration_cpu_stop - this will be executed by a highprio stopper thread
4781 * and performs thread migration by bumping thread off CPU then
4782 * 'pushing' onto another runqueue.
4784 static int migration_cpu_stop(void *data)
4786 struct migration_arg *arg = data;
4789 * The original target cpu might have gone down and we might
4790 * be on another cpu but it doesn't matter.
4792 local_irq_disable();
4793 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4798 #ifdef CONFIG_HOTPLUG_CPU
4801 * Ensures that the idle task is using init_mm right before its cpu goes
4804 void idle_task_exit(void)
4806 struct mm_struct *mm = current->active_mm;
4808 BUG_ON(cpu_online(smp_processor_id()));
4810 if (mm != &init_mm) {
4811 switch_mm(mm, &init_mm, current);
4812 finish_arch_post_lock_switch();
4818 * Since this CPU is going 'away' for a while, fold any nr_active delta
4819 * we might have. Assumes we're called after migrate_tasks() so that the
4820 * nr_active count is stable.
4822 * Also see the comment "Global load-average calculations".
4824 static void calc_load_migrate(struct rq *rq)
4826 long delta = calc_load_fold_active(rq);
4828 atomic_long_add(delta, &calc_load_tasks);
4831 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
4835 static const struct sched_class fake_sched_class = {
4836 .put_prev_task = put_prev_task_fake,
4839 static struct task_struct fake_task = {
4841 * Avoid pull_{rt,dl}_task()
4843 .prio = MAX_PRIO + 1,
4844 .sched_class = &fake_sched_class,
4848 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4849 * try_to_wake_up()->select_task_rq().
4851 * Called with rq->lock held even though we'er in stop_machine() and
4852 * there's no concurrency possible, we hold the required locks anyway
4853 * because of lock validation efforts.
4855 static void migrate_tasks(unsigned int dead_cpu)
4857 struct rq *rq = cpu_rq(dead_cpu);
4858 struct task_struct *next, *stop = rq->stop;
4862 * Fudge the rq selection such that the below task selection loop
4863 * doesn't get stuck on the currently eligible stop task.
4865 * We're currently inside stop_machine() and the rq is either stuck
4866 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4867 * either way we should never end up calling schedule() until we're
4873 * put_prev_task() and pick_next_task() sched
4874 * class method both need to have an up-to-date
4875 * value of rq->clock[_task]
4877 update_rq_clock(rq);
4881 * There's this thread running, bail when that's the only
4884 if (rq->nr_running == 1)
4887 next = pick_next_task(rq, &fake_task);
4889 next->sched_class->put_prev_task(rq, next);
4891 /* Find suitable destination for @next, with force if needed. */
4892 dest_cpu = select_fallback_rq(dead_cpu, next);
4893 raw_spin_unlock(&rq->lock);
4895 __migrate_task(next, dead_cpu, dest_cpu);
4897 raw_spin_lock(&rq->lock);
4903 #endif /* CONFIG_HOTPLUG_CPU */
4905 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4907 static struct ctl_table sd_ctl_dir[] = {
4909 .procname = "sched_domain",
4915 static struct ctl_table sd_ctl_root[] = {
4917 .procname = "kernel",
4919 .child = sd_ctl_dir,
4924 static struct ctl_table *sd_alloc_ctl_entry(int n)
4926 struct ctl_table *entry =
4927 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4932 static void sd_free_ctl_entry(struct ctl_table **tablep)
4934 struct ctl_table *entry;
4937 * In the intermediate directories, both the child directory and
4938 * procname are dynamically allocated and could fail but the mode
4939 * will always be set. In the lowest directory the names are
4940 * static strings and all have proc handlers.
4942 for (entry = *tablep; entry->mode; entry++) {
4944 sd_free_ctl_entry(&entry->child);
4945 if (entry->proc_handler == NULL)
4946 kfree(entry->procname);
4953 static int min_load_idx = 0;
4954 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
4957 set_table_entry(struct ctl_table *entry,
4958 const char *procname, void *data, int maxlen,
4959 umode_t mode, proc_handler *proc_handler,
4962 entry->procname = procname;
4964 entry->maxlen = maxlen;
4966 entry->proc_handler = proc_handler;
4969 entry->extra1 = &min_load_idx;
4970 entry->extra2 = &max_load_idx;
4974 static struct ctl_table *
4975 sd_alloc_ctl_domain_table(struct sched_domain *sd)
4977 struct ctl_table *table = sd_alloc_ctl_entry(14);
4982 set_table_entry(&table[0], "min_interval", &sd->min_interval,
4983 sizeof(long), 0644, proc_doulongvec_minmax, false);
4984 set_table_entry(&table[1], "max_interval", &sd->max_interval,
4985 sizeof(long), 0644, proc_doulongvec_minmax, false);
4986 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4987 sizeof(int), 0644, proc_dointvec_minmax, true);
4988 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4989 sizeof(int), 0644, proc_dointvec_minmax, true);
4990 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4991 sizeof(int), 0644, proc_dointvec_minmax, true);
4992 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4993 sizeof(int), 0644, proc_dointvec_minmax, true);
4994 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4995 sizeof(int), 0644, proc_dointvec_minmax, true);
4996 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4997 sizeof(int), 0644, proc_dointvec_minmax, false);
4998 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4999 sizeof(int), 0644, proc_dointvec_minmax, false);
5000 set_table_entry(&table[9], "cache_nice_tries",
5001 &sd->cache_nice_tries,
5002 sizeof(int), 0644, proc_dointvec_minmax, false);
5003 set_table_entry(&table[10], "flags", &sd->flags,
5004 sizeof(int), 0644, proc_dointvec_minmax, false);
5005 set_table_entry(&table[11], "max_newidle_lb_cost",
5006 &sd->max_newidle_lb_cost,
5007 sizeof(long), 0644, proc_doulongvec_minmax, false);
5008 set_table_entry(&table[12], "name", sd->name,
5009 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
5010 /* &table[13] is terminator */
5015 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5017 struct ctl_table *entry, *table;
5018 struct sched_domain *sd;
5019 int domain_num = 0, i;
5022 for_each_domain(cpu, sd)
5024 entry = table = sd_alloc_ctl_entry(domain_num + 1);
5029 for_each_domain(cpu, sd) {
5030 snprintf(buf, 32, "domain%d", i);
5031 entry->procname = kstrdup(buf, GFP_KERNEL);
5033 entry->child = sd_alloc_ctl_domain_table(sd);
5040 static struct ctl_table_header *sd_sysctl_header;
5041 static void register_sched_domain_sysctl(void)
5043 int i, cpu_num = num_possible_cpus();
5044 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5047 WARN_ON(sd_ctl_dir[0].child);
5048 sd_ctl_dir[0].child = entry;
5053 for_each_possible_cpu(i) {
5054 snprintf(buf, 32, "cpu%d", i);
5055 entry->procname = kstrdup(buf, GFP_KERNEL);
5057 entry->child = sd_alloc_ctl_cpu_table(i);
5061 WARN_ON(sd_sysctl_header);
5062 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5065 /* may be called multiple times per register */
5066 static void unregister_sched_domain_sysctl(void)
5068 if (sd_sysctl_header)
5069 unregister_sysctl_table(sd_sysctl_header);
5070 sd_sysctl_header = NULL;
5071 if (sd_ctl_dir[0].child)
5072 sd_free_ctl_entry(&sd_ctl_dir[0].child);
5075 static void register_sched_domain_sysctl(void)
5078 static void unregister_sched_domain_sysctl(void)
5083 static void set_rq_online(struct rq *rq)
5086 const struct sched_class *class;
5088 cpumask_set_cpu(rq->cpu, rq->rd->online);
5091 for_each_class(class) {
5092 if (class->rq_online)
5093 class->rq_online(rq);
5098 static void set_rq_offline(struct rq *rq)
5101 const struct sched_class *class;
5103 for_each_class(class) {
5104 if (class->rq_offline)
5105 class->rq_offline(rq);
5108 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5114 * migration_call - callback that gets triggered when a CPU is added.
5115 * Here we can start up the necessary migration thread for the new CPU.
5118 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5120 int cpu = (long)hcpu;
5121 unsigned long flags;
5122 struct rq *rq = cpu_rq(cpu);
5124 switch (action & ~CPU_TASKS_FROZEN) {
5126 case CPU_UP_PREPARE:
5127 rq->calc_load_update = calc_load_update;
5131 /* Update our root-domain */
5132 raw_spin_lock_irqsave(&rq->lock, flags);
5134 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5138 raw_spin_unlock_irqrestore(&rq->lock, flags);
5141 #ifdef CONFIG_HOTPLUG_CPU
5143 sched_ttwu_pending();
5144 /* Update our root-domain */
5145 raw_spin_lock_irqsave(&rq->lock, flags);
5147 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5151 BUG_ON(rq->nr_running != 1); /* the migration thread */
5152 raw_spin_unlock_irqrestore(&rq->lock, flags);
5156 calc_load_migrate(rq);
5161 update_max_interval();
5167 * Register at high priority so that task migration (migrate_all_tasks)
5168 * happens before everything else. This has to be lower priority than
5169 * the notifier in the perf_event subsystem, though.
5171 static struct notifier_block migration_notifier = {
5172 .notifier_call = migration_call,
5173 .priority = CPU_PRI_MIGRATION,
5176 static void __cpuinit set_cpu_rq_start_time(void)
5178 int cpu = smp_processor_id();
5179 struct rq *rq = cpu_rq(cpu);
5180 rq->age_stamp = sched_clock_cpu(cpu);
5183 static int sched_cpu_active(struct notifier_block *nfb,
5184 unsigned long action, void *hcpu)
5186 switch (action & ~CPU_TASKS_FROZEN) {
5188 set_cpu_rq_start_time();
5190 case CPU_DOWN_FAILED:
5191 set_cpu_active((long)hcpu, true);
5198 static int sched_cpu_inactive(struct notifier_block *nfb,
5199 unsigned long action, void *hcpu)
5201 unsigned long flags;
5202 long cpu = (long)hcpu;
5204 switch (action & ~CPU_TASKS_FROZEN) {
5205 case CPU_DOWN_PREPARE:
5206 set_cpu_active(cpu, false);
5208 /* explicitly allow suspend */
5209 if (!(action & CPU_TASKS_FROZEN)) {
5210 struct dl_bw *dl_b = dl_bw_of(cpu);
5214 raw_spin_lock_irqsave(&dl_b->lock, flags);
5215 cpus = dl_bw_cpus(cpu);
5216 overflow = __dl_overflow(dl_b, cpus, 0, 0);
5217 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5220 return notifier_from_errno(-EBUSY);
5228 static int __init migration_init(void)
5230 void *cpu = (void *)(long)smp_processor_id();
5233 /* Initialize migration for the boot CPU */
5234 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5235 BUG_ON(err == NOTIFY_BAD);
5236 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5237 register_cpu_notifier(&migration_notifier);
5239 /* Register cpu active notifiers */
5240 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5241 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5245 early_initcall(migration_init);
5250 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5252 #ifdef CONFIG_SCHED_DEBUG
5254 static __read_mostly int sched_debug_enabled;
5256 static int __init sched_debug_setup(char *str)
5258 sched_debug_enabled = 1;
5262 early_param("sched_debug", sched_debug_setup);
5264 static inline bool sched_debug(void)
5266 return sched_debug_enabled;
5269 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5270 struct cpumask *groupmask)
5272 struct sched_group *group = sd->groups;
5275 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5276 cpumask_clear(groupmask);
5278 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5280 if (!(sd->flags & SD_LOAD_BALANCE)) {
5281 printk("does not load-balance\n");
5283 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5288 printk(KERN_CONT "span %s level %s\n", str, sd->name);
5290 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5291 printk(KERN_ERR "ERROR: domain->span does not contain "
5294 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5295 printk(KERN_ERR "ERROR: domain->groups does not contain"
5299 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5303 printk(KERN_ERR "ERROR: group is NULL\n");
5308 * Even though we initialize ->capacity to something semi-sane,
5309 * we leave capacity_orig unset. This allows us to detect if
5310 * domain iteration is still funny without causing /0 traps.
5312 if (!group->sgc->capacity_orig) {
5313 printk(KERN_CONT "\n");
5314 printk(KERN_ERR "ERROR: domain->cpu_capacity not set\n");
5318 if (!cpumask_weight(sched_group_cpus(group))) {
5319 printk(KERN_CONT "\n");
5320 printk(KERN_ERR "ERROR: empty group\n");
5324 if (!(sd->flags & SD_OVERLAP) &&
5325 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5326 printk(KERN_CONT "\n");
5327 printk(KERN_ERR "ERROR: repeated CPUs\n");
5331 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5333 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5335 printk(KERN_CONT " %s", str);
5336 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5337 printk(KERN_CONT " (cpu_capacity = %d)",
5338 group->sgc->capacity);
5341 group = group->next;
5342 } while (group != sd->groups);
5343 printk(KERN_CONT "\n");
5345 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5346 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5349 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5350 printk(KERN_ERR "ERROR: parent span is not a superset "
5351 "of domain->span\n");
5355 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5359 if (!sched_debug_enabled)
5363 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5367 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5370 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5378 #else /* !CONFIG_SCHED_DEBUG */
5379 # define sched_domain_debug(sd, cpu) do { } while (0)
5380 static inline bool sched_debug(void)
5384 #endif /* CONFIG_SCHED_DEBUG */
5386 static int sd_degenerate(struct sched_domain *sd)
5388 if (cpumask_weight(sched_domain_span(sd)) == 1)
5391 /* Following flags need at least 2 groups */
5392 if (sd->flags & (SD_LOAD_BALANCE |
5393 SD_BALANCE_NEWIDLE |
5396 SD_SHARE_CPUCAPACITY |
5397 SD_SHARE_PKG_RESOURCES |
5398 SD_SHARE_POWERDOMAIN)) {
5399 if (sd->groups != sd->groups->next)
5403 /* Following flags don't use groups */
5404 if (sd->flags & (SD_WAKE_AFFINE))
5411 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5413 unsigned long cflags = sd->flags, pflags = parent->flags;
5415 if (sd_degenerate(parent))
5418 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5421 /* Flags needing groups don't count if only 1 group in parent */
5422 if (parent->groups == parent->groups->next) {
5423 pflags &= ~(SD_LOAD_BALANCE |
5424 SD_BALANCE_NEWIDLE |
5427 SD_SHARE_CPUCAPACITY |
5428 SD_SHARE_PKG_RESOURCES |
5430 SD_SHARE_POWERDOMAIN);
5431 if (nr_node_ids == 1)
5432 pflags &= ~SD_SERIALIZE;
5434 if (~cflags & pflags)
5440 static void free_rootdomain(struct rcu_head *rcu)
5442 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5444 cpupri_cleanup(&rd->cpupri);
5445 cpudl_cleanup(&rd->cpudl);
5446 free_cpumask_var(rd->dlo_mask);
5447 free_cpumask_var(rd->rto_mask);
5448 free_cpumask_var(rd->online);
5449 free_cpumask_var(rd->span);
5453 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5455 struct root_domain *old_rd = NULL;
5456 unsigned long flags;
5458 raw_spin_lock_irqsave(&rq->lock, flags);
5463 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5466 cpumask_clear_cpu(rq->cpu, old_rd->span);
5469 * If we dont want to free the old_rd yet then
5470 * set old_rd to NULL to skip the freeing later
5473 if (!atomic_dec_and_test(&old_rd->refcount))
5477 atomic_inc(&rd->refcount);
5480 cpumask_set_cpu(rq->cpu, rd->span);
5481 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5484 raw_spin_unlock_irqrestore(&rq->lock, flags);
5487 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5490 static int init_rootdomain(struct root_domain *rd)
5492 memset(rd, 0, sizeof(*rd));
5494 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5496 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5498 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5500 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5503 init_dl_bw(&rd->dl_bw);
5504 if (cpudl_init(&rd->cpudl) != 0)
5507 if (cpupri_init(&rd->cpupri) != 0)
5512 free_cpumask_var(rd->rto_mask);
5514 free_cpumask_var(rd->dlo_mask);
5516 free_cpumask_var(rd->online);
5518 free_cpumask_var(rd->span);
5524 * By default the system creates a single root-domain with all cpus as
5525 * members (mimicking the global state we have today).
5527 struct root_domain def_root_domain;
5529 static void init_defrootdomain(void)
5531 init_rootdomain(&def_root_domain);
5533 atomic_set(&def_root_domain.refcount, 1);
5536 static struct root_domain *alloc_rootdomain(void)
5538 struct root_domain *rd;
5540 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5544 if (init_rootdomain(rd) != 0) {
5552 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5554 struct sched_group *tmp, *first;
5563 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5568 } while (sg != first);
5571 static void free_sched_domain(struct rcu_head *rcu)
5573 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5576 * If its an overlapping domain it has private groups, iterate and
5579 if (sd->flags & SD_OVERLAP) {
5580 free_sched_groups(sd->groups, 1);
5581 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5582 kfree(sd->groups->sgc);
5588 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5590 call_rcu(&sd->rcu, free_sched_domain);
5593 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5595 for (; sd; sd = sd->parent)
5596 destroy_sched_domain(sd, cpu);
5600 * Keep a special pointer to the highest sched_domain that has
5601 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5602 * allows us to avoid some pointer chasing select_idle_sibling().
5604 * Also keep a unique ID per domain (we use the first cpu number in
5605 * the cpumask of the domain), this allows us to quickly tell if
5606 * two cpus are in the same cache domain, see cpus_share_cache().
5608 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5609 DEFINE_PER_CPU(int, sd_llc_size);
5610 DEFINE_PER_CPU(int, sd_llc_id);
5611 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5612 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5613 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5615 static void update_top_cache_domain(int cpu)
5617 struct sched_domain *sd;
5618 struct sched_domain *busy_sd = NULL;
5622 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5624 id = cpumask_first(sched_domain_span(sd));
5625 size = cpumask_weight(sched_domain_span(sd));
5626 busy_sd = sd->parent; /* sd_busy */
5628 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5630 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5631 per_cpu(sd_llc_size, cpu) = size;
5632 per_cpu(sd_llc_id, cpu) = id;
5634 sd = lowest_flag_domain(cpu, SD_NUMA);
5635 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5637 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5638 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5642 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5643 * hold the hotplug lock.
5646 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5648 struct rq *rq = cpu_rq(cpu);
5649 struct sched_domain *tmp;
5651 /* Remove the sched domains which do not contribute to scheduling. */
5652 for (tmp = sd; tmp; ) {
5653 struct sched_domain *parent = tmp->parent;
5657 if (sd_parent_degenerate(tmp, parent)) {
5658 tmp->parent = parent->parent;
5660 parent->parent->child = tmp;
5662 * Transfer SD_PREFER_SIBLING down in case of a
5663 * degenerate parent; the spans match for this
5664 * so the property transfers.
5666 if (parent->flags & SD_PREFER_SIBLING)
5667 tmp->flags |= SD_PREFER_SIBLING;
5668 destroy_sched_domain(parent, cpu);
5673 if (sd && sd_degenerate(sd)) {
5676 destroy_sched_domain(tmp, cpu);
5681 sched_domain_debug(sd, cpu);
5683 rq_attach_root(rq, rd);
5685 rcu_assign_pointer(rq->sd, sd);
5686 destroy_sched_domains(tmp, cpu);
5688 update_top_cache_domain(cpu);
5691 /* cpus with isolated domains */
5692 static cpumask_var_t cpu_isolated_map;
5694 /* Setup the mask of cpus configured for isolated domains */
5695 static int __init isolated_cpu_setup(char *str)
5697 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5698 cpulist_parse(str, cpu_isolated_map);
5702 __setup("isolcpus=", isolated_cpu_setup);
5705 struct sched_domain ** __percpu sd;
5706 struct root_domain *rd;
5717 * Build an iteration mask that can exclude certain CPUs from the upwards
5720 * Asymmetric node setups can result in situations where the domain tree is of
5721 * unequal depth, make sure to skip domains that already cover the entire
5724 * In that case build_sched_domains() will have terminated the iteration early
5725 * and our sibling sd spans will be empty. Domains should always include the
5726 * cpu they're built on, so check that.
5729 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5731 const struct cpumask *span = sched_domain_span(sd);
5732 struct sd_data *sdd = sd->private;
5733 struct sched_domain *sibling;
5736 for_each_cpu(i, span) {
5737 sibling = *per_cpu_ptr(sdd->sd, i);
5738 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5741 cpumask_set_cpu(i, sched_group_mask(sg));
5746 * Return the canonical balance cpu for this group, this is the first cpu
5747 * of this group that's also in the iteration mask.
5749 int group_balance_cpu(struct sched_group *sg)
5751 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5755 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5757 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5758 const struct cpumask *span = sched_domain_span(sd);
5759 struct cpumask *covered = sched_domains_tmpmask;
5760 struct sd_data *sdd = sd->private;
5761 struct sched_domain *child;
5764 cpumask_clear(covered);
5766 for_each_cpu(i, span) {
5767 struct cpumask *sg_span;
5769 if (cpumask_test_cpu(i, covered))
5772 child = *per_cpu_ptr(sdd->sd, i);
5774 /* See the comment near build_group_mask(). */
5775 if (!cpumask_test_cpu(i, sched_domain_span(child)))
5778 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5779 GFP_KERNEL, cpu_to_node(cpu));
5784 sg_span = sched_group_cpus(sg);
5786 child = child->child;
5787 cpumask_copy(sg_span, sched_domain_span(child));
5789 cpumask_set_cpu(i, sg_span);
5791 cpumask_or(covered, covered, sg_span);
5793 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
5794 if (atomic_inc_return(&sg->sgc->ref) == 1)
5795 build_group_mask(sd, sg);
5798 * Initialize sgc->capacity such that even if we mess up the
5799 * domains and no possible iteration will get us here, we won't
5802 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
5803 sg->sgc->capacity_orig = sg->sgc->capacity;
5806 * Make sure the first group of this domain contains the
5807 * canonical balance cpu. Otherwise the sched_domain iteration
5808 * breaks. See update_sg_lb_stats().
5810 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5811 group_balance_cpu(sg) == cpu)
5821 sd->groups = groups;
5826 free_sched_groups(first, 0);
5831 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5833 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5834 struct sched_domain *child = sd->child;
5837 cpu = cpumask_first(sched_domain_span(child));
5840 *sg = *per_cpu_ptr(sdd->sg, cpu);
5841 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
5842 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
5849 * build_sched_groups will build a circular linked list of the groups
5850 * covered by the given span, and will set each group's ->cpumask correctly,
5851 * and ->cpu_capacity to 0.
5853 * Assumes the sched_domain tree is fully constructed
5856 build_sched_groups(struct sched_domain *sd, int cpu)
5858 struct sched_group *first = NULL, *last = NULL;
5859 struct sd_data *sdd = sd->private;
5860 const struct cpumask *span = sched_domain_span(sd);
5861 struct cpumask *covered;
5864 get_group(cpu, sdd, &sd->groups);
5865 atomic_inc(&sd->groups->ref);
5867 if (cpu != cpumask_first(span))
5870 lockdep_assert_held(&sched_domains_mutex);
5871 covered = sched_domains_tmpmask;
5873 cpumask_clear(covered);
5875 for_each_cpu(i, span) {
5876 struct sched_group *sg;
5879 if (cpumask_test_cpu(i, covered))
5882 group = get_group(i, sdd, &sg);
5883 cpumask_setall(sched_group_mask(sg));
5885 for_each_cpu(j, span) {
5886 if (get_group(j, sdd, NULL) != group)
5889 cpumask_set_cpu(j, covered);
5890 cpumask_set_cpu(j, sched_group_cpus(sg));
5905 * Initialize sched groups cpu_capacity.
5907 * cpu_capacity indicates the capacity of sched group, which is used while
5908 * distributing the load between different sched groups in a sched domain.
5909 * Typically cpu_capacity for all the groups in a sched domain will be same
5910 * unless there are asymmetries in the topology. If there are asymmetries,
5911 * group having more cpu_capacity will pickup more load compared to the
5912 * group having less cpu_capacity.
5914 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
5916 struct sched_group *sg = sd->groups;
5921 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5923 } while (sg != sd->groups);
5925 if (cpu != group_balance_cpu(sg))
5928 update_group_capacity(sd, cpu);
5929 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
5933 * Initializers for schedule domains
5934 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5937 static int default_relax_domain_level = -1;
5938 int sched_domain_level_max;
5940 static int __init setup_relax_domain_level(char *str)
5942 if (kstrtoint(str, 0, &default_relax_domain_level))
5943 pr_warn("Unable to set relax_domain_level\n");
5947 __setup("relax_domain_level=", setup_relax_domain_level);
5949 static void set_domain_attribute(struct sched_domain *sd,
5950 struct sched_domain_attr *attr)
5954 if (!attr || attr->relax_domain_level < 0) {
5955 if (default_relax_domain_level < 0)
5958 request = default_relax_domain_level;
5960 request = attr->relax_domain_level;
5961 if (request < sd->level) {
5962 /* turn off idle balance on this domain */
5963 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5965 /* turn on idle balance on this domain */
5966 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5970 static void __sdt_free(const struct cpumask *cpu_map);
5971 static int __sdt_alloc(const struct cpumask *cpu_map);
5973 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5974 const struct cpumask *cpu_map)
5978 if (!atomic_read(&d->rd->refcount))
5979 free_rootdomain(&d->rd->rcu); /* fall through */
5981 free_percpu(d->sd); /* fall through */
5983 __sdt_free(cpu_map); /* fall through */
5989 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5990 const struct cpumask *cpu_map)
5992 memset(d, 0, sizeof(*d));
5994 if (__sdt_alloc(cpu_map))
5995 return sa_sd_storage;
5996 d->sd = alloc_percpu(struct sched_domain *);
5998 return sa_sd_storage;
5999 d->rd = alloc_rootdomain();
6002 return sa_rootdomain;
6006 * NULL the sd_data elements we've used to build the sched_domain and
6007 * sched_group structure so that the subsequent __free_domain_allocs()
6008 * will not free the data we're using.
6010 static void claim_allocations(int cpu, struct sched_domain *sd)
6012 struct sd_data *sdd = sd->private;
6014 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6015 *per_cpu_ptr(sdd->sd, cpu) = NULL;
6017 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6018 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6020 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6021 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6025 static int sched_domains_numa_levels;
6026 static int *sched_domains_numa_distance;
6027 static struct cpumask ***sched_domains_numa_masks;
6028 static int sched_domains_curr_level;
6032 * SD_flags allowed in topology descriptions.
6034 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6035 * SD_SHARE_PKG_RESOURCES - describes shared caches
6036 * SD_NUMA - describes NUMA topologies
6037 * SD_SHARE_POWERDOMAIN - describes shared power domain
6040 * SD_ASYM_PACKING - describes SMT quirks
6042 #define TOPOLOGY_SD_FLAGS \
6043 (SD_SHARE_CPUCAPACITY | \
6044 SD_SHARE_PKG_RESOURCES | \
6047 SD_SHARE_POWERDOMAIN)
6049 static struct sched_domain *
6050 sd_init(struct sched_domain_topology_level *tl, int cpu)
6052 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6053 int sd_weight, sd_flags = 0;
6057 * Ugly hack to pass state to sd_numa_mask()...
6059 sched_domains_curr_level = tl->numa_level;
6062 sd_weight = cpumask_weight(tl->mask(cpu));
6065 sd_flags = (*tl->sd_flags)();
6066 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6067 "wrong sd_flags in topology description\n"))
6068 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6070 *sd = (struct sched_domain){
6071 .min_interval = sd_weight,
6072 .max_interval = 2*sd_weight,
6074 .imbalance_pct = 125,
6076 .cache_nice_tries = 0,
6083 .flags = 1*SD_LOAD_BALANCE
6084 | 1*SD_BALANCE_NEWIDLE
6089 | 0*SD_SHARE_CPUCAPACITY
6090 | 0*SD_SHARE_PKG_RESOURCES
6092 | 0*SD_PREFER_SIBLING
6097 .last_balance = jiffies,
6098 .balance_interval = sd_weight,
6100 .max_newidle_lb_cost = 0,
6101 .next_decay_max_lb_cost = jiffies,
6102 #ifdef CONFIG_SCHED_DEBUG
6108 * Convert topological properties into behaviour.
6111 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6112 sd->imbalance_pct = 110;
6113 sd->smt_gain = 1178; /* ~15% */
6115 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6116 sd->imbalance_pct = 117;
6117 sd->cache_nice_tries = 1;
6121 } else if (sd->flags & SD_NUMA) {
6122 sd->cache_nice_tries = 2;
6126 sd->flags |= SD_SERIALIZE;
6127 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6128 sd->flags &= ~(SD_BALANCE_EXEC |
6135 sd->flags |= SD_PREFER_SIBLING;
6136 sd->cache_nice_tries = 1;
6141 sd->private = &tl->data;
6147 * Topology list, bottom-up.
6149 static struct sched_domain_topology_level default_topology[] = {
6150 #ifdef CONFIG_SCHED_SMT
6151 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6153 #ifdef CONFIG_SCHED_MC
6154 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6156 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6160 struct sched_domain_topology_level *sched_domain_topology = default_topology;
6162 #define for_each_sd_topology(tl) \
6163 for (tl = sched_domain_topology; tl->mask; tl++)
6165 void set_sched_topology(struct sched_domain_topology_level *tl)
6167 sched_domain_topology = tl;
6172 static const struct cpumask *sd_numa_mask(int cpu)
6174 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6177 static void sched_numa_warn(const char *str)
6179 static int done = false;
6187 printk(KERN_WARNING "ERROR: %s\n\n", str);
6189 for (i = 0; i < nr_node_ids; i++) {
6190 printk(KERN_WARNING " ");
6191 for (j = 0; j < nr_node_ids; j++)
6192 printk(KERN_CONT "%02d ", node_distance(i,j));
6193 printk(KERN_CONT "\n");
6195 printk(KERN_WARNING "\n");
6198 static bool find_numa_distance(int distance)
6202 if (distance == node_distance(0, 0))
6205 for (i = 0; i < sched_domains_numa_levels; i++) {
6206 if (sched_domains_numa_distance[i] == distance)
6213 static void sched_init_numa(void)
6215 int next_distance, curr_distance = node_distance(0, 0);
6216 struct sched_domain_topology_level *tl;
6220 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6221 if (!sched_domains_numa_distance)
6225 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6226 * unique distances in the node_distance() table.
6228 * Assumes node_distance(0,j) includes all distances in
6229 * node_distance(i,j) in order to avoid cubic time.
6231 next_distance = curr_distance;
6232 for (i = 0; i < nr_node_ids; i++) {
6233 for (j = 0; j < nr_node_ids; j++) {
6234 for (k = 0; k < nr_node_ids; k++) {
6235 int distance = node_distance(i, k);
6237 if (distance > curr_distance &&
6238 (distance < next_distance ||
6239 next_distance == curr_distance))
6240 next_distance = distance;
6243 * While not a strong assumption it would be nice to know
6244 * about cases where if node A is connected to B, B is not
6245 * equally connected to A.
6247 if (sched_debug() && node_distance(k, i) != distance)
6248 sched_numa_warn("Node-distance not symmetric");
6250 if (sched_debug() && i && !find_numa_distance(distance))
6251 sched_numa_warn("Node-0 not representative");
6253 if (next_distance != curr_distance) {
6254 sched_domains_numa_distance[level++] = next_distance;
6255 sched_domains_numa_levels = level;
6256 curr_distance = next_distance;
6261 * In case of sched_debug() we verify the above assumption.
6267 * 'level' contains the number of unique distances, excluding the
6268 * identity distance node_distance(i,i).
6270 * The sched_domains_numa_distance[] array includes the actual distance
6275 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6276 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6277 * the array will contain less then 'level' members. This could be
6278 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6279 * in other functions.
6281 * We reset it to 'level' at the end of this function.
6283 sched_domains_numa_levels = 0;
6285 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6286 if (!sched_domains_numa_masks)
6290 * Now for each level, construct a mask per node which contains all
6291 * cpus of nodes that are that many hops away from us.
6293 for (i = 0; i < level; i++) {
6294 sched_domains_numa_masks[i] =
6295 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6296 if (!sched_domains_numa_masks[i])
6299 for (j = 0; j < nr_node_ids; j++) {
6300 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6304 sched_domains_numa_masks[i][j] = mask;
6306 for (k = 0; k < nr_node_ids; k++) {
6307 if (node_distance(j, k) > sched_domains_numa_distance[i])
6310 cpumask_or(mask, mask, cpumask_of_node(k));
6315 /* Compute default topology size */
6316 for (i = 0; sched_domain_topology[i].mask; i++);
6318 tl = kzalloc((i + level + 1) *
6319 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6324 * Copy the default topology bits..
6326 for (i = 0; sched_domain_topology[i].mask; i++)
6327 tl[i] = sched_domain_topology[i];
6330 * .. and append 'j' levels of NUMA goodness.
6332 for (j = 0; j < level; i++, j++) {
6333 tl[i] = (struct sched_domain_topology_level){
6334 .mask = sd_numa_mask,
6335 .sd_flags = cpu_numa_flags,
6336 .flags = SDTL_OVERLAP,
6342 sched_domain_topology = tl;
6344 sched_domains_numa_levels = level;
6347 static void sched_domains_numa_masks_set(int cpu)
6350 int node = cpu_to_node(cpu);
6352 for (i = 0; i < sched_domains_numa_levels; i++) {
6353 for (j = 0; j < nr_node_ids; j++) {
6354 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6355 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6360 static void sched_domains_numa_masks_clear(int cpu)
6363 for (i = 0; i < sched_domains_numa_levels; i++) {
6364 for (j = 0; j < nr_node_ids; j++)
6365 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6370 * Update sched_domains_numa_masks[level][node] array when new cpus
6373 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6374 unsigned long action,
6377 int cpu = (long)hcpu;
6379 switch (action & ~CPU_TASKS_FROZEN) {
6381 sched_domains_numa_masks_set(cpu);
6385 sched_domains_numa_masks_clear(cpu);
6395 static inline void sched_init_numa(void)
6399 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6400 unsigned long action,
6405 #endif /* CONFIG_NUMA */
6407 static int __sdt_alloc(const struct cpumask *cpu_map)
6409 struct sched_domain_topology_level *tl;
6412 for_each_sd_topology(tl) {
6413 struct sd_data *sdd = &tl->data;
6415 sdd->sd = alloc_percpu(struct sched_domain *);
6419 sdd->sg = alloc_percpu(struct sched_group *);
6423 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6427 for_each_cpu(j, cpu_map) {
6428 struct sched_domain *sd;
6429 struct sched_group *sg;
6430 struct sched_group_capacity *sgc;
6432 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6433 GFP_KERNEL, cpu_to_node(j));
6437 *per_cpu_ptr(sdd->sd, j) = sd;
6439 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6440 GFP_KERNEL, cpu_to_node(j));
6446 *per_cpu_ptr(sdd->sg, j) = sg;
6448 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6449 GFP_KERNEL, cpu_to_node(j));
6453 *per_cpu_ptr(sdd->sgc, j) = sgc;
6460 static void __sdt_free(const struct cpumask *cpu_map)
6462 struct sched_domain_topology_level *tl;
6465 for_each_sd_topology(tl) {
6466 struct sd_data *sdd = &tl->data;
6468 for_each_cpu(j, cpu_map) {
6469 struct sched_domain *sd;
6472 sd = *per_cpu_ptr(sdd->sd, j);
6473 if (sd && (sd->flags & SD_OVERLAP))
6474 free_sched_groups(sd->groups, 0);
6475 kfree(*per_cpu_ptr(sdd->sd, j));
6479 kfree(*per_cpu_ptr(sdd->sg, j));
6481 kfree(*per_cpu_ptr(sdd->sgc, j));
6483 free_percpu(sdd->sd);
6485 free_percpu(sdd->sg);
6487 free_percpu(sdd->sgc);
6492 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6493 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6494 struct sched_domain *child, int cpu)
6496 struct sched_domain *sd = sd_init(tl, cpu);
6500 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6502 sd->level = child->level + 1;
6503 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6507 if (!cpumask_subset(sched_domain_span(child),
6508 sched_domain_span(sd))) {
6509 pr_err("BUG: arch topology borken\n");
6510 #ifdef CONFIG_SCHED_DEBUG
6511 pr_err(" the %s domain not a subset of the %s domain\n",
6512 child->name, sd->name);
6514 /* Fixup, ensure @sd has at least @child cpus. */
6515 cpumask_or(sched_domain_span(sd),
6516 sched_domain_span(sd),
6517 sched_domain_span(child));
6521 set_domain_attribute(sd, attr);
6527 * Build sched domains for a given set of cpus and attach the sched domains
6528 * to the individual cpus
6530 static int build_sched_domains(const struct cpumask *cpu_map,
6531 struct sched_domain_attr *attr)
6533 enum s_alloc alloc_state;
6534 struct sched_domain *sd;
6536 int i, ret = -ENOMEM;
6538 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6539 if (alloc_state != sa_rootdomain)
6542 /* Set up domains for cpus specified by the cpu_map. */
6543 for_each_cpu(i, cpu_map) {
6544 struct sched_domain_topology_level *tl;
6547 for_each_sd_topology(tl) {
6548 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6549 if (tl == sched_domain_topology)
6550 *per_cpu_ptr(d.sd, i) = sd;
6551 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6552 sd->flags |= SD_OVERLAP;
6553 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6558 /* Build the groups for the domains */
6559 for_each_cpu(i, cpu_map) {
6560 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6561 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6562 if (sd->flags & SD_OVERLAP) {
6563 if (build_overlap_sched_groups(sd, i))
6566 if (build_sched_groups(sd, i))
6572 /* Calculate CPU capacity for physical packages and nodes */
6573 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6574 if (!cpumask_test_cpu(i, cpu_map))
6577 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6578 claim_allocations(i, sd);
6579 init_sched_groups_capacity(i, sd);
6583 /* Attach the domains */
6585 for_each_cpu(i, cpu_map) {
6586 sd = *per_cpu_ptr(d.sd, i);
6587 cpu_attach_domain(sd, d.rd, i);
6593 __free_domain_allocs(&d, alloc_state, cpu_map);
6597 static cpumask_var_t *doms_cur; /* current sched domains */
6598 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6599 static struct sched_domain_attr *dattr_cur;
6600 /* attribues of custom domains in 'doms_cur' */
6603 * Special case: If a kmalloc of a doms_cur partition (array of
6604 * cpumask) fails, then fallback to a single sched domain,
6605 * as determined by the single cpumask fallback_doms.
6607 static cpumask_var_t fallback_doms;
6610 * arch_update_cpu_topology lets virtualized architectures update the
6611 * cpu core maps. It is supposed to return 1 if the topology changed
6612 * or 0 if it stayed the same.
6614 int __weak arch_update_cpu_topology(void)
6619 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6622 cpumask_var_t *doms;
6624 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6627 for (i = 0; i < ndoms; i++) {
6628 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6629 free_sched_domains(doms, i);
6636 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6639 for (i = 0; i < ndoms; i++)
6640 free_cpumask_var(doms[i]);
6645 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6646 * For now this just excludes isolated cpus, but could be used to
6647 * exclude other special cases in the future.
6649 static int init_sched_domains(const struct cpumask *cpu_map)
6653 arch_update_cpu_topology();
6655 doms_cur = alloc_sched_domains(ndoms_cur);
6657 doms_cur = &fallback_doms;
6658 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6659 err = build_sched_domains(doms_cur[0], NULL);
6660 register_sched_domain_sysctl();
6666 * Detach sched domains from a group of cpus specified in cpu_map
6667 * These cpus will now be attached to the NULL domain
6669 static void detach_destroy_domains(const struct cpumask *cpu_map)
6674 for_each_cpu(i, cpu_map)
6675 cpu_attach_domain(NULL, &def_root_domain, i);
6679 /* handle null as "default" */
6680 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6681 struct sched_domain_attr *new, int idx_new)
6683 struct sched_domain_attr tmp;
6690 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6691 new ? (new + idx_new) : &tmp,
6692 sizeof(struct sched_domain_attr));
6696 * Partition sched domains as specified by the 'ndoms_new'
6697 * cpumasks in the array doms_new[] of cpumasks. This compares
6698 * doms_new[] to the current sched domain partitioning, doms_cur[].
6699 * It destroys each deleted domain and builds each new domain.
6701 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6702 * The masks don't intersect (don't overlap.) We should setup one
6703 * sched domain for each mask. CPUs not in any of the cpumasks will
6704 * not be load balanced. If the same cpumask appears both in the
6705 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6708 * The passed in 'doms_new' should be allocated using
6709 * alloc_sched_domains. This routine takes ownership of it and will
6710 * free_sched_domains it when done with it. If the caller failed the
6711 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6712 * and partition_sched_domains() will fallback to the single partition
6713 * 'fallback_doms', it also forces the domains to be rebuilt.
6715 * If doms_new == NULL it will be replaced with cpu_online_mask.
6716 * ndoms_new == 0 is a special case for destroying existing domains,
6717 * and it will not create the default domain.
6719 * Call with hotplug lock held
6721 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
6722 struct sched_domain_attr *dattr_new)
6727 mutex_lock(&sched_domains_mutex);
6729 /* always unregister in case we don't destroy any domains */
6730 unregister_sched_domain_sysctl();
6732 /* Let architecture update cpu core mappings. */
6733 new_topology = arch_update_cpu_topology();
6735 n = doms_new ? ndoms_new : 0;
6737 /* Destroy deleted domains */
6738 for (i = 0; i < ndoms_cur; i++) {
6739 for (j = 0; j < n && !new_topology; j++) {
6740 if (cpumask_equal(doms_cur[i], doms_new[j])
6741 && dattrs_equal(dattr_cur, i, dattr_new, j))
6744 /* no match - a current sched domain not in new doms_new[] */
6745 detach_destroy_domains(doms_cur[i]);
6751 if (doms_new == NULL) {
6753 doms_new = &fallback_doms;
6754 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6755 WARN_ON_ONCE(dattr_new);
6758 /* Build new domains */
6759 for (i = 0; i < ndoms_new; i++) {
6760 for (j = 0; j < n && !new_topology; j++) {
6761 if (cpumask_equal(doms_new[i], doms_cur[j])
6762 && dattrs_equal(dattr_new, i, dattr_cur, j))
6765 /* no match - add a new doms_new */
6766 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6771 /* Remember the new sched domains */
6772 if (doms_cur != &fallback_doms)
6773 free_sched_domains(doms_cur, ndoms_cur);
6774 kfree(dattr_cur); /* kfree(NULL) is safe */
6775 doms_cur = doms_new;
6776 dattr_cur = dattr_new;
6777 ndoms_cur = ndoms_new;
6779 register_sched_domain_sysctl();
6781 mutex_unlock(&sched_domains_mutex);
6784 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
6787 * Update cpusets according to cpu_active mask. If cpusets are
6788 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6789 * around partition_sched_domains().
6791 * If we come here as part of a suspend/resume, don't touch cpusets because we
6792 * want to restore it back to its original state upon resume anyway.
6794 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6798 case CPU_ONLINE_FROZEN:
6799 case CPU_DOWN_FAILED_FROZEN:
6802 * num_cpus_frozen tracks how many CPUs are involved in suspend
6803 * resume sequence. As long as this is not the last online
6804 * operation in the resume sequence, just build a single sched
6805 * domain, ignoring cpusets.
6808 if (likely(num_cpus_frozen)) {
6809 partition_sched_domains(1, NULL, NULL);
6814 * This is the last CPU online operation. So fall through and
6815 * restore the original sched domains by considering the
6816 * cpuset configurations.
6820 case CPU_DOWN_FAILED:
6821 cpuset_update_active_cpus(true);
6829 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6833 case CPU_DOWN_PREPARE:
6834 cpuset_update_active_cpus(false);
6836 case CPU_DOWN_PREPARE_FROZEN:
6838 partition_sched_domains(1, NULL, NULL);
6846 void __init sched_init_smp(void)
6848 cpumask_var_t non_isolated_cpus;
6850 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6851 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6856 * There's no userspace yet to cause hotplug operations; hence all the
6857 * cpu masks are stable and all blatant races in the below code cannot
6860 mutex_lock(&sched_domains_mutex);
6861 init_sched_domains(cpu_active_mask);
6862 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6863 if (cpumask_empty(non_isolated_cpus))
6864 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6865 mutex_unlock(&sched_domains_mutex);
6867 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6868 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6869 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6873 /* Move init over to a non-isolated CPU */
6874 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6876 sched_init_granularity();
6877 free_cpumask_var(non_isolated_cpus);
6879 init_sched_rt_class();
6880 init_sched_dl_class();
6883 void __init sched_init_smp(void)
6885 sched_init_granularity();
6887 #endif /* CONFIG_SMP */
6889 const_debug unsigned int sysctl_timer_migration = 1;
6891 int in_sched_functions(unsigned long addr)
6893 return in_lock_functions(addr) ||
6894 (addr >= (unsigned long)__sched_text_start
6895 && addr < (unsigned long)__sched_text_end);
6898 #ifdef CONFIG_CGROUP_SCHED
6900 * Default task group.
6901 * Every task in system belongs to this group at bootup.
6903 struct task_group root_task_group;
6904 LIST_HEAD(task_groups);
6907 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6909 void __init sched_init(void)
6912 unsigned long alloc_size = 0, ptr;
6914 #ifdef CONFIG_FAIR_GROUP_SCHED
6915 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6917 #ifdef CONFIG_RT_GROUP_SCHED
6918 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6920 #ifdef CONFIG_CPUMASK_OFFSTACK
6921 alloc_size += num_possible_cpus() * cpumask_size();
6924 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6926 #ifdef CONFIG_FAIR_GROUP_SCHED
6927 root_task_group.se = (struct sched_entity **)ptr;
6928 ptr += nr_cpu_ids * sizeof(void **);
6930 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6931 ptr += nr_cpu_ids * sizeof(void **);
6933 #endif /* CONFIG_FAIR_GROUP_SCHED */
6934 #ifdef CONFIG_RT_GROUP_SCHED
6935 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
6936 ptr += nr_cpu_ids * sizeof(void **);
6938 root_task_group.rt_rq = (struct rt_rq **)ptr;
6939 ptr += nr_cpu_ids * sizeof(void **);
6941 #endif /* CONFIG_RT_GROUP_SCHED */
6942 #ifdef CONFIG_CPUMASK_OFFSTACK
6943 for_each_possible_cpu(i) {
6944 per_cpu(load_balance_mask, i) = (void *)ptr;
6945 ptr += cpumask_size();
6947 #endif /* CONFIG_CPUMASK_OFFSTACK */
6950 init_rt_bandwidth(&def_rt_bandwidth,
6951 global_rt_period(), global_rt_runtime());
6952 init_dl_bandwidth(&def_dl_bandwidth,
6953 global_rt_period(), global_rt_runtime());
6956 init_defrootdomain();
6959 #ifdef CONFIG_RT_GROUP_SCHED
6960 init_rt_bandwidth(&root_task_group.rt_bandwidth,
6961 global_rt_period(), global_rt_runtime());
6962 #endif /* CONFIG_RT_GROUP_SCHED */
6964 #ifdef CONFIG_CGROUP_SCHED
6965 list_add(&root_task_group.list, &task_groups);
6966 INIT_LIST_HEAD(&root_task_group.children);
6967 INIT_LIST_HEAD(&root_task_group.siblings);
6968 autogroup_init(&init_task);
6970 #endif /* CONFIG_CGROUP_SCHED */
6972 for_each_possible_cpu(i) {
6976 raw_spin_lock_init(&rq->lock);
6978 rq->calc_load_active = 0;
6979 rq->calc_load_update = jiffies + LOAD_FREQ;
6980 init_cfs_rq(&rq->cfs);
6981 init_rt_rq(&rq->rt, rq);
6982 init_dl_rq(&rq->dl, rq);
6983 #ifdef CONFIG_FAIR_GROUP_SCHED
6984 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6985 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6987 * How much cpu bandwidth does root_task_group get?
6989 * In case of task-groups formed thr' the cgroup filesystem, it
6990 * gets 100% of the cpu resources in the system. This overall
6991 * system cpu resource is divided among the tasks of
6992 * root_task_group and its child task-groups in a fair manner,
6993 * based on each entity's (task or task-group's) weight
6994 * (se->load.weight).
6996 * In other words, if root_task_group has 10 tasks of weight
6997 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6998 * then A0's share of the cpu resource is:
7000 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7002 * We achieve this by letting root_task_group's tasks sit
7003 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7005 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7006 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7007 #endif /* CONFIG_FAIR_GROUP_SCHED */
7009 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7010 #ifdef CONFIG_RT_GROUP_SCHED
7011 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7014 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7015 rq->cpu_load[j] = 0;
7017 rq->last_load_update_tick = jiffies;
7022 rq->cpu_capacity = SCHED_CAPACITY_SCALE;
7023 rq->post_schedule = 0;
7024 rq->active_balance = 0;
7025 rq->next_balance = jiffies;
7030 rq->avg_idle = 2*sysctl_sched_migration_cost;
7031 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7033 INIT_LIST_HEAD(&rq->cfs_tasks);
7035 rq_attach_root(rq, &def_root_domain);
7036 #ifdef CONFIG_NO_HZ_COMMON
7039 #ifdef CONFIG_NO_HZ_FULL
7040 rq->last_sched_tick = 0;
7044 atomic_set(&rq->nr_iowait, 0);
7047 set_load_weight(&init_task);
7049 #ifdef CONFIG_PREEMPT_NOTIFIERS
7050 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7054 * The boot idle thread does lazy MMU switching as well:
7056 atomic_inc(&init_mm.mm_count);
7057 enter_lazy_tlb(&init_mm, current);
7060 * Make us the idle thread. Technically, schedule() should not be
7061 * called from this thread, however somewhere below it might be,
7062 * but because we are the idle thread, we just pick up running again
7063 * when this runqueue becomes "idle".
7065 init_idle(current, smp_processor_id());
7067 calc_load_update = jiffies + LOAD_FREQ;
7070 * During early bootup we pretend to be a normal task:
7072 current->sched_class = &fair_sched_class;
7075 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7076 /* May be allocated at isolcpus cmdline parse time */
7077 if (cpu_isolated_map == NULL)
7078 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7079 idle_thread_set_boot_cpu();
7080 set_cpu_rq_start_time();
7082 init_sched_fair_class();
7084 scheduler_running = 1;
7087 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7088 static inline int preempt_count_equals(int preempt_offset)
7090 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
7092 return (nested == preempt_offset);
7095 void __might_sleep(const char *file, int line, int preempt_offset)
7097 static unsigned long prev_jiffy; /* ratelimiting */
7099 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7100 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7101 !is_idle_task(current)) ||
7102 system_state != SYSTEM_RUNNING || oops_in_progress)
7104 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7106 prev_jiffy = jiffies;
7109 "BUG: sleeping function called from invalid context at %s:%d\n",
7112 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7113 in_atomic(), irqs_disabled(),
7114 current->pid, current->comm);
7116 debug_show_held_locks(current);
7117 if (irqs_disabled())
7118 print_irqtrace_events(current);
7119 #ifdef CONFIG_DEBUG_PREEMPT
7120 if (!preempt_count_equals(preempt_offset)) {
7121 pr_err("Preemption disabled at:");
7122 print_ip_sym(current->preempt_disable_ip);
7128 EXPORT_SYMBOL(__might_sleep);
7131 #ifdef CONFIG_MAGIC_SYSRQ
7132 static void normalize_task(struct rq *rq, struct task_struct *p)
7134 const struct sched_class *prev_class = p->sched_class;
7135 struct sched_attr attr = {
7136 .sched_policy = SCHED_NORMAL,
7138 int old_prio = p->prio;
7143 dequeue_task(rq, p, 0);
7144 __setscheduler(rq, p, &attr);
7146 enqueue_task(rq, p, 0);
7150 check_class_changed(rq, p, prev_class, old_prio);
7153 void normalize_rt_tasks(void)
7155 struct task_struct *g, *p;
7156 unsigned long flags;
7159 read_lock_irqsave(&tasklist_lock, flags);
7160 do_each_thread(g, p) {
7162 * Only normalize user tasks:
7167 p->se.exec_start = 0;
7168 #ifdef CONFIG_SCHEDSTATS
7169 p->se.statistics.wait_start = 0;
7170 p->se.statistics.sleep_start = 0;
7171 p->se.statistics.block_start = 0;
7174 if (!dl_task(p) && !rt_task(p)) {
7176 * Renice negative nice level userspace
7179 if (task_nice(p) < 0 && p->mm)
7180 set_user_nice(p, 0);
7184 raw_spin_lock(&p->pi_lock);
7185 rq = __task_rq_lock(p);
7187 normalize_task(rq, p);
7189 __task_rq_unlock(rq);
7190 raw_spin_unlock(&p->pi_lock);
7191 } while_each_thread(g, p);
7193 read_unlock_irqrestore(&tasklist_lock, flags);
7196 #endif /* CONFIG_MAGIC_SYSRQ */
7198 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7200 * These functions are only useful for the IA64 MCA handling, or kdb.
7202 * They can only be called when the whole system has been
7203 * stopped - every CPU needs to be quiescent, and no scheduling
7204 * activity can take place. Using them for anything else would
7205 * be a serious bug, and as a result, they aren't even visible
7206 * under any other configuration.
7210 * curr_task - return the current task for a given cpu.
7211 * @cpu: the processor in question.
7213 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7215 * Return: The current task for @cpu.
7217 struct task_struct *curr_task(int cpu)
7219 return cpu_curr(cpu);
7222 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7226 * set_curr_task - set the current task for a given cpu.
7227 * @cpu: the processor in question.
7228 * @p: the task pointer to set.
7230 * Description: This function must only be used when non-maskable interrupts
7231 * are serviced on a separate stack. It allows the architecture to switch the
7232 * notion of the current task on a cpu in a non-blocking manner. This function
7233 * must be called with all CPU's synchronized, and interrupts disabled, the
7234 * and caller must save the original value of the current task (see
7235 * curr_task() above) and restore that value before reenabling interrupts and
7236 * re-starting the system.
7238 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7240 void set_curr_task(int cpu, struct task_struct *p)
7247 #ifdef CONFIG_CGROUP_SCHED
7248 /* task_group_lock serializes the addition/removal of task groups */
7249 static DEFINE_SPINLOCK(task_group_lock);
7251 static void free_sched_group(struct task_group *tg)
7253 free_fair_sched_group(tg);
7254 free_rt_sched_group(tg);
7259 /* allocate runqueue etc for a new task group */
7260 struct task_group *sched_create_group(struct task_group *parent)
7262 struct task_group *tg;
7264 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7266 return ERR_PTR(-ENOMEM);
7268 if (!alloc_fair_sched_group(tg, parent))
7271 if (!alloc_rt_sched_group(tg, parent))
7277 free_sched_group(tg);
7278 return ERR_PTR(-ENOMEM);
7281 void sched_online_group(struct task_group *tg, struct task_group *parent)
7283 unsigned long flags;
7285 spin_lock_irqsave(&task_group_lock, flags);
7286 list_add_rcu(&tg->list, &task_groups);
7288 WARN_ON(!parent); /* root should already exist */
7290 tg->parent = parent;
7291 INIT_LIST_HEAD(&tg->children);
7292 list_add_rcu(&tg->siblings, &parent->children);
7293 spin_unlock_irqrestore(&task_group_lock, flags);
7296 /* rcu callback to free various structures associated with a task group */
7297 static void free_sched_group_rcu(struct rcu_head *rhp)
7299 /* now it should be safe to free those cfs_rqs */
7300 free_sched_group(container_of(rhp, struct task_group, rcu));
7303 /* Destroy runqueue etc associated with a task group */
7304 void sched_destroy_group(struct task_group *tg)
7306 /* wait for possible concurrent references to cfs_rqs complete */
7307 call_rcu(&tg->rcu, free_sched_group_rcu);
7310 void sched_offline_group(struct task_group *tg)
7312 unsigned long flags;
7315 /* end participation in shares distribution */
7316 for_each_possible_cpu(i)
7317 unregister_fair_sched_group(tg, i);
7319 spin_lock_irqsave(&task_group_lock, flags);
7320 list_del_rcu(&tg->list);
7321 list_del_rcu(&tg->siblings);
7322 spin_unlock_irqrestore(&task_group_lock, flags);
7325 /* change task's runqueue when it moves between groups.
7326 * The caller of this function should have put the task in its new group
7327 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7328 * reflect its new group.
7330 void sched_move_task(struct task_struct *tsk)
7332 struct task_group *tg;
7334 unsigned long flags;
7337 rq = task_rq_lock(tsk, &flags);
7339 running = task_current(rq, tsk);
7343 dequeue_task(rq, tsk, 0);
7344 if (unlikely(running))
7345 tsk->sched_class->put_prev_task(rq, tsk);
7347 tg = container_of(task_css_check(tsk, cpu_cgrp_id,
7348 lockdep_is_held(&tsk->sighand->siglock)),
7349 struct task_group, css);
7350 tg = autogroup_task_group(tsk, tg);
7351 tsk->sched_task_group = tg;
7353 #ifdef CONFIG_FAIR_GROUP_SCHED
7354 if (tsk->sched_class->task_move_group)
7355 tsk->sched_class->task_move_group(tsk, on_rq);
7358 set_task_rq(tsk, task_cpu(tsk));
7360 if (unlikely(running))
7361 tsk->sched_class->set_curr_task(rq);
7363 enqueue_task(rq, tsk, 0);
7365 task_rq_unlock(rq, tsk, &flags);
7367 #endif /* CONFIG_CGROUP_SCHED */
7369 #ifdef CONFIG_RT_GROUP_SCHED
7371 * Ensure that the real time constraints are schedulable.
7373 static DEFINE_MUTEX(rt_constraints_mutex);
7375 /* Must be called with tasklist_lock held */
7376 static inline int tg_has_rt_tasks(struct task_group *tg)
7378 struct task_struct *g, *p;
7380 do_each_thread(g, p) {
7381 if (rt_task(p) && task_rq(p)->rt.tg == tg)
7383 } while_each_thread(g, p);
7388 struct rt_schedulable_data {
7389 struct task_group *tg;
7394 static int tg_rt_schedulable(struct task_group *tg, void *data)
7396 struct rt_schedulable_data *d = data;
7397 struct task_group *child;
7398 unsigned long total, sum = 0;
7399 u64 period, runtime;
7401 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7402 runtime = tg->rt_bandwidth.rt_runtime;
7405 period = d->rt_period;
7406 runtime = d->rt_runtime;
7410 * Cannot have more runtime than the period.
7412 if (runtime > period && runtime != RUNTIME_INF)
7416 * Ensure we don't starve existing RT tasks.
7418 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7421 total = to_ratio(period, runtime);
7424 * Nobody can have more than the global setting allows.
7426 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7430 * The sum of our children's runtime should not exceed our own.
7432 list_for_each_entry_rcu(child, &tg->children, siblings) {
7433 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7434 runtime = child->rt_bandwidth.rt_runtime;
7436 if (child == d->tg) {
7437 period = d->rt_period;
7438 runtime = d->rt_runtime;
7441 sum += to_ratio(period, runtime);
7450 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7454 struct rt_schedulable_data data = {
7456 .rt_period = period,
7457 .rt_runtime = runtime,
7461 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7467 static int tg_set_rt_bandwidth(struct task_group *tg,
7468 u64 rt_period, u64 rt_runtime)
7472 mutex_lock(&rt_constraints_mutex);
7473 read_lock(&tasklist_lock);
7474 err = __rt_schedulable(tg, rt_period, rt_runtime);
7478 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7479 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7480 tg->rt_bandwidth.rt_runtime = rt_runtime;
7482 for_each_possible_cpu(i) {
7483 struct rt_rq *rt_rq = tg->rt_rq[i];
7485 raw_spin_lock(&rt_rq->rt_runtime_lock);
7486 rt_rq->rt_runtime = rt_runtime;
7487 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7489 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7491 read_unlock(&tasklist_lock);
7492 mutex_unlock(&rt_constraints_mutex);
7497 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7499 u64 rt_runtime, rt_period;
7501 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7502 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7503 if (rt_runtime_us < 0)
7504 rt_runtime = RUNTIME_INF;
7506 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7509 static long sched_group_rt_runtime(struct task_group *tg)
7513 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7516 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7517 do_div(rt_runtime_us, NSEC_PER_USEC);
7518 return rt_runtime_us;
7521 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
7523 u64 rt_runtime, rt_period;
7525 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
7526 rt_runtime = tg->rt_bandwidth.rt_runtime;
7531 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7534 static long sched_group_rt_period(struct task_group *tg)
7538 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7539 do_div(rt_period_us, NSEC_PER_USEC);
7540 return rt_period_us;
7542 #endif /* CONFIG_RT_GROUP_SCHED */
7544 #ifdef CONFIG_RT_GROUP_SCHED
7545 static int sched_rt_global_constraints(void)
7549 mutex_lock(&rt_constraints_mutex);
7550 read_lock(&tasklist_lock);
7551 ret = __rt_schedulable(NULL, 0, 0);
7552 read_unlock(&tasklist_lock);
7553 mutex_unlock(&rt_constraints_mutex);
7558 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7560 /* Don't accept realtime tasks when there is no way for them to run */
7561 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7567 #else /* !CONFIG_RT_GROUP_SCHED */
7568 static int sched_rt_global_constraints(void)
7570 unsigned long flags;
7573 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7574 for_each_possible_cpu(i) {
7575 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7577 raw_spin_lock(&rt_rq->rt_runtime_lock);
7578 rt_rq->rt_runtime = global_rt_runtime();
7579 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7581 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7585 #endif /* CONFIG_RT_GROUP_SCHED */
7587 static int sched_dl_global_constraints(void)
7589 u64 runtime = global_rt_runtime();
7590 u64 period = global_rt_period();
7591 u64 new_bw = to_ratio(period, runtime);
7593 unsigned long flags;
7596 * Here we want to check the bandwidth not being set to some
7597 * value smaller than the currently allocated bandwidth in
7598 * any of the root_domains.
7600 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7601 * cycling on root_domains... Discussion on different/better
7602 * solutions is welcome!
7604 for_each_possible_cpu(cpu) {
7605 struct dl_bw *dl_b = dl_bw_of(cpu);
7607 raw_spin_lock_irqsave(&dl_b->lock, flags);
7608 if (new_bw < dl_b->total_bw)
7610 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7619 static void sched_dl_do_global(void)
7623 unsigned long flags;
7625 def_dl_bandwidth.dl_period = global_rt_period();
7626 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7628 if (global_rt_runtime() != RUNTIME_INF)
7629 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7632 * FIXME: As above...
7634 for_each_possible_cpu(cpu) {
7635 struct dl_bw *dl_b = dl_bw_of(cpu);
7637 raw_spin_lock_irqsave(&dl_b->lock, flags);
7639 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7643 static int sched_rt_global_validate(void)
7645 if (sysctl_sched_rt_period <= 0)
7648 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7649 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7655 static void sched_rt_do_global(void)
7657 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7658 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7661 int sched_rt_handler(struct ctl_table *table, int write,
7662 void __user *buffer, size_t *lenp,
7665 int old_period, old_runtime;
7666 static DEFINE_MUTEX(mutex);
7670 old_period = sysctl_sched_rt_period;
7671 old_runtime = sysctl_sched_rt_runtime;
7673 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7675 if (!ret && write) {
7676 ret = sched_rt_global_validate();
7680 ret = sched_rt_global_constraints();
7684 ret = sched_dl_global_constraints();
7688 sched_rt_do_global();
7689 sched_dl_do_global();
7693 sysctl_sched_rt_period = old_period;
7694 sysctl_sched_rt_runtime = old_runtime;
7696 mutex_unlock(&mutex);
7701 int sched_rr_handler(struct ctl_table *table, int write,
7702 void __user *buffer, size_t *lenp,
7706 static DEFINE_MUTEX(mutex);
7709 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7710 /* make sure that internally we keep jiffies */
7711 /* also, writing zero resets timeslice to default */
7712 if (!ret && write) {
7713 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
7714 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
7716 mutex_unlock(&mutex);
7720 #ifdef CONFIG_CGROUP_SCHED
7722 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
7724 return css ? container_of(css, struct task_group, css) : NULL;
7727 static struct cgroup_subsys_state *
7728 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
7730 struct task_group *parent = css_tg(parent_css);
7731 struct task_group *tg;
7734 /* This is early initialization for the top cgroup */
7735 return &root_task_group.css;
7738 tg = sched_create_group(parent);
7740 return ERR_PTR(-ENOMEM);
7745 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
7747 struct task_group *tg = css_tg(css);
7748 struct task_group *parent = css_tg(css->parent);
7751 sched_online_group(tg, parent);
7755 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
7757 struct task_group *tg = css_tg(css);
7759 sched_destroy_group(tg);
7762 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
7764 struct task_group *tg = css_tg(css);
7766 sched_offline_group(tg);
7769 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
7770 struct cgroup_taskset *tset)
7772 struct task_struct *task;
7774 cgroup_taskset_for_each(task, tset) {
7775 #ifdef CONFIG_RT_GROUP_SCHED
7776 if (!sched_rt_can_attach(css_tg(css), task))
7779 /* We don't support RT-tasks being in separate groups */
7780 if (task->sched_class != &fair_sched_class)
7787 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
7788 struct cgroup_taskset *tset)
7790 struct task_struct *task;
7792 cgroup_taskset_for_each(task, tset)
7793 sched_move_task(task);
7796 static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7797 struct cgroup_subsys_state *old_css,
7798 struct task_struct *task)
7801 * cgroup_exit() is called in the copy_process() failure path.
7802 * Ignore this case since the task hasn't ran yet, this avoids
7803 * trying to poke a half freed task state from generic code.
7805 if (!(task->flags & PF_EXITING))
7808 sched_move_task(task);
7811 #ifdef CONFIG_FAIR_GROUP_SCHED
7812 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7813 struct cftype *cftype, u64 shareval)
7815 return sched_group_set_shares(css_tg(css), scale_load(shareval));
7818 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7821 struct task_group *tg = css_tg(css);
7823 return (u64) scale_load_down(tg->shares);
7826 #ifdef CONFIG_CFS_BANDWIDTH
7827 static DEFINE_MUTEX(cfs_constraints_mutex);
7829 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7830 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7832 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7834 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7836 int i, ret = 0, runtime_enabled, runtime_was_enabled;
7837 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7839 if (tg == &root_task_group)
7843 * Ensure we have at some amount of bandwidth every period. This is
7844 * to prevent reaching a state of large arrears when throttled via
7845 * entity_tick() resulting in prolonged exit starvation.
7847 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7851 * Likewise, bound things on the otherside by preventing insane quota
7852 * periods. This also allows us to normalize in computing quota
7855 if (period > max_cfs_quota_period)
7859 * Prevent race between setting of cfs_rq->runtime_enabled and
7860 * unthrottle_offline_cfs_rqs().
7863 mutex_lock(&cfs_constraints_mutex);
7864 ret = __cfs_schedulable(tg, period, quota);
7868 runtime_enabled = quota != RUNTIME_INF;
7869 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7871 * If we need to toggle cfs_bandwidth_used, off->on must occur
7872 * before making related changes, and on->off must occur afterwards
7874 if (runtime_enabled && !runtime_was_enabled)
7875 cfs_bandwidth_usage_inc();
7876 raw_spin_lock_irq(&cfs_b->lock);
7877 cfs_b->period = ns_to_ktime(period);
7878 cfs_b->quota = quota;
7880 __refill_cfs_bandwidth_runtime(cfs_b);
7881 /* restart the period timer (if active) to handle new period expiry */
7882 if (runtime_enabled && cfs_b->timer_active) {
7883 /* force a reprogram */
7884 __start_cfs_bandwidth(cfs_b, true);
7886 raw_spin_unlock_irq(&cfs_b->lock);
7888 for_each_online_cpu(i) {
7889 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7890 struct rq *rq = cfs_rq->rq;
7892 raw_spin_lock_irq(&rq->lock);
7893 cfs_rq->runtime_enabled = runtime_enabled;
7894 cfs_rq->runtime_remaining = 0;
7896 if (cfs_rq->throttled)
7897 unthrottle_cfs_rq(cfs_rq);
7898 raw_spin_unlock_irq(&rq->lock);
7900 if (runtime_was_enabled && !runtime_enabled)
7901 cfs_bandwidth_usage_dec();
7903 mutex_unlock(&cfs_constraints_mutex);
7909 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7913 period = ktime_to_ns(tg->cfs_bandwidth.period);
7914 if (cfs_quota_us < 0)
7915 quota = RUNTIME_INF;
7917 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7919 return tg_set_cfs_bandwidth(tg, period, quota);
7922 long tg_get_cfs_quota(struct task_group *tg)
7926 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7929 quota_us = tg->cfs_bandwidth.quota;
7930 do_div(quota_us, NSEC_PER_USEC);
7935 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
7939 period = (u64)cfs_period_us * NSEC_PER_USEC;
7940 quota = tg->cfs_bandwidth.quota;
7942 return tg_set_cfs_bandwidth(tg, period, quota);
7945 long tg_get_cfs_period(struct task_group *tg)
7949 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
7950 do_div(cfs_period_us, NSEC_PER_USEC);
7952 return cfs_period_us;
7955 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
7958 return tg_get_cfs_quota(css_tg(css));
7961 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
7962 struct cftype *cftype, s64 cfs_quota_us)
7964 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
7967 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
7970 return tg_get_cfs_period(css_tg(css));
7973 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
7974 struct cftype *cftype, u64 cfs_period_us)
7976 return tg_set_cfs_period(css_tg(css), cfs_period_us);
7979 struct cfs_schedulable_data {
7980 struct task_group *tg;
7985 * normalize group quota/period to be quota/max_period
7986 * note: units are usecs
7988 static u64 normalize_cfs_quota(struct task_group *tg,
7989 struct cfs_schedulable_data *d)
7997 period = tg_get_cfs_period(tg);
7998 quota = tg_get_cfs_quota(tg);
8001 /* note: these should typically be equivalent */
8002 if (quota == RUNTIME_INF || quota == -1)
8005 return to_ratio(period, quota);
8008 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8010 struct cfs_schedulable_data *d = data;
8011 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8012 s64 quota = 0, parent_quota = -1;
8015 quota = RUNTIME_INF;
8017 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8019 quota = normalize_cfs_quota(tg, d);
8020 parent_quota = parent_b->hierarchal_quota;
8023 * ensure max(child_quota) <= parent_quota, inherit when no
8026 if (quota == RUNTIME_INF)
8027 quota = parent_quota;
8028 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8031 cfs_b->hierarchal_quota = quota;
8036 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8039 struct cfs_schedulable_data data = {
8045 if (quota != RUNTIME_INF) {
8046 do_div(data.period, NSEC_PER_USEC);
8047 do_div(data.quota, NSEC_PER_USEC);
8051 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8057 static int cpu_stats_show(struct seq_file *sf, void *v)
8059 struct task_group *tg = css_tg(seq_css(sf));
8060 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8062 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8063 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8064 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8068 #endif /* CONFIG_CFS_BANDWIDTH */
8069 #endif /* CONFIG_FAIR_GROUP_SCHED */
8071 #ifdef CONFIG_RT_GROUP_SCHED
8072 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8073 struct cftype *cft, s64 val)
8075 return sched_group_set_rt_runtime(css_tg(css), val);
8078 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8081 return sched_group_rt_runtime(css_tg(css));
8084 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8085 struct cftype *cftype, u64 rt_period_us)
8087 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8090 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8093 return sched_group_rt_period(css_tg(css));
8095 #endif /* CONFIG_RT_GROUP_SCHED */
8097 static struct cftype cpu_files[] = {
8098 #ifdef CONFIG_FAIR_GROUP_SCHED
8101 .read_u64 = cpu_shares_read_u64,
8102 .write_u64 = cpu_shares_write_u64,
8105 #ifdef CONFIG_CFS_BANDWIDTH
8107 .name = "cfs_quota_us",
8108 .read_s64 = cpu_cfs_quota_read_s64,
8109 .write_s64 = cpu_cfs_quota_write_s64,
8112 .name = "cfs_period_us",
8113 .read_u64 = cpu_cfs_period_read_u64,
8114 .write_u64 = cpu_cfs_period_write_u64,
8118 .seq_show = cpu_stats_show,
8121 #ifdef CONFIG_RT_GROUP_SCHED
8123 .name = "rt_runtime_us",
8124 .read_s64 = cpu_rt_runtime_read,
8125 .write_s64 = cpu_rt_runtime_write,
8128 .name = "rt_period_us",
8129 .read_u64 = cpu_rt_period_read_uint,
8130 .write_u64 = cpu_rt_period_write_uint,
8136 struct cgroup_subsys cpu_cgrp_subsys = {
8137 .css_alloc = cpu_cgroup_css_alloc,
8138 .css_free = cpu_cgroup_css_free,
8139 .css_online = cpu_cgroup_css_online,
8140 .css_offline = cpu_cgroup_css_offline,
8141 .can_attach = cpu_cgroup_can_attach,
8142 .attach = cpu_cgroup_attach,
8143 .exit = cpu_cgroup_exit,
8144 .legacy_cftypes = cpu_files,
8148 #endif /* CONFIG_CGROUP_SCHED */
8150 void dump_cpu_task(int cpu)
8152 pr_info("Task dump for CPU %d:\n", cpu);
8153 sched_show_task(cpu_curr(cpu));