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 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
96 ktime_t soft, hard, now;
99 if (hrtimer_active(period_timer))
102 now = hrtimer_cb_get_time(period_timer);
103 hrtimer_forward(period_timer, now, period);
105 soft = hrtimer_get_softexpires(period_timer);
106 hard = hrtimer_get_expires(period_timer);
107 delta = ktime_to_ns(ktime_sub(hard, soft));
108 __hrtimer_start_range_ns(period_timer, soft, delta,
109 HRTIMER_MODE_ABS_PINNED, 0);
113 DEFINE_MUTEX(sched_domains_mutex);
114 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
116 static void update_rq_clock_task(struct rq *rq, s64 delta);
118 void update_rq_clock(struct rq *rq)
122 if (rq->skip_clock_update > 0)
125 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
127 update_rq_clock_task(rq, delta);
131 * Debugging: various feature bits
134 #define SCHED_FEAT(name, enabled) \
135 (1UL << __SCHED_FEAT_##name) * enabled |
137 const_debug unsigned int sysctl_sched_features =
138 #include "features.h"
143 #ifdef CONFIG_SCHED_DEBUG
144 #define SCHED_FEAT(name, enabled) \
147 static const char * const sched_feat_names[] = {
148 #include "features.h"
153 static int sched_feat_show(struct seq_file *m, void *v)
157 for (i = 0; i < __SCHED_FEAT_NR; i++) {
158 if (!(sysctl_sched_features & (1UL << i)))
160 seq_printf(m, "%s ", sched_feat_names[i]);
167 #ifdef HAVE_JUMP_LABEL
169 #define jump_label_key__true STATIC_KEY_INIT_TRUE
170 #define jump_label_key__false STATIC_KEY_INIT_FALSE
172 #define SCHED_FEAT(name, enabled) \
173 jump_label_key__##enabled ,
175 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
176 #include "features.h"
181 static void sched_feat_disable(int i)
183 if (static_key_enabled(&sched_feat_keys[i]))
184 static_key_slow_dec(&sched_feat_keys[i]);
187 static void sched_feat_enable(int i)
189 if (!static_key_enabled(&sched_feat_keys[i]))
190 static_key_slow_inc(&sched_feat_keys[i]);
193 static void sched_feat_disable(int i) { };
194 static void sched_feat_enable(int i) { };
195 #endif /* HAVE_JUMP_LABEL */
197 static int sched_feat_set(char *cmp)
202 if (strncmp(cmp, "NO_", 3) == 0) {
207 for (i = 0; i < __SCHED_FEAT_NR; i++) {
208 if (strcmp(cmp, sched_feat_names[i]) == 0) {
210 sysctl_sched_features &= ~(1UL << i);
211 sched_feat_disable(i);
213 sysctl_sched_features |= (1UL << i);
214 sched_feat_enable(i);
224 sched_feat_write(struct file *filp, const char __user *ubuf,
225 size_t cnt, loff_t *ppos)
234 if (copy_from_user(&buf, ubuf, cnt))
240 i = sched_feat_set(cmp);
241 if (i == __SCHED_FEAT_NR)
249 static int sched_feat_open(struct inode *inode, struct file *filp)
251 return single_open(filp, sched_feat_show, NULL);
254 static const struct file_operations sched_feat_fops = {
255 .open = sched_feat_open,
256 .write = sched_feat_write,
259 .release = single_release,
262 static __init int sched_init_debug(void)
264 debugfs_create_file("sched_features", 0644, NULL, NULL,
269 late_initcall(sched_init_debug);
270 #endif /* CONFIG_SCHED_DEBUG */
273 * Number of tasks to iterate in a single balance run.
274 * Limited because this is done with IRQs disabled.
276 const_debug unsigned int sysctl_sched_nr_migrate = 32;
279 * period over which we average the RT time consumption, measured
284 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
287 * period over which we measure -rt task cpu usage in us.
290 unsigned int sysctl_sched_rt_period = 1000000;
292 __read_mostly int scheduler_running;
295 * part of the period that we allow rt tasks to run in us.
298 int sysctl_sched_rt_runtime = 950000;
301 * __task_rq_lock - lock the rq @p resides on.
303 static inline struct rq *__task_rq_lock(struct task_struct *p)
308 lockdep_assert_held(&p->pi_lock);
312 raw_spin_lock(&rq->lock);
313 if (likely(rq == task_rq(p)))
315 raw_spin_unlock(&rq->lock);
320 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
322 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
323 __acquires(p->pi_lock)
329 raw_spin_lock_irqsave(&p->pi_lock, *flags);
331 raw_spin_lock(&rq->lock);
332 if (likely(rq == task_rq(p)))
334 raw_spin_unlock(&rq->lock);
335 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
339 static void __task_rq_unlock(struct rq *rq)
342 raw_spin_unlock(&rq->lock);
346 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
348 __releases(p->pi_lock)
350 raw_spin_unlock(&rq->lock);
351 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
355 * this_rq_lock - lock this runqueue and disable interrupts.
357 static struct rq *this_rq_lock(void)
364 raw_spin_lock(&rq->lock);
369 #ifdef CONFIG_SCHED_HRTICK
371 * Use HR-timers to deliver accurate preemption points.
374 static void hrtick_clear(struct rq *rq)
376 if (hrtimer_active(&rq->hrtick_timer))
377 hrtimer_cancel(&rq->hrtick_timer);
381 * High-resolution timer tick.
382 * Runs from hardirq context with interrupts disabled.
384 static enum hrtimer_restart hrtick(struct hrtimer *timer)
386 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
388 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
390 raw_spin_lock(&rq->lock);
392 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
393 raw_spin_unlock(&rq->lock);
395 return HRTIMER_NORESTART;
400 static int __hrtick_restart(struct rq *rq)
402 struct hrtimer *timer = &rq->hrtick_timer;
403 ktime_t time = hrtimer_get_softexpires(timer);
405 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
409 * called from hardirq (IPI) context
411 static void __hrtick_start(void *arg)
415 raw_spin_lock(&rq->lock);
416 __hrtick_restart(rq);
417 rq->hrtick_csd_pending = 0;
418 raw_spin_unlock(&rq->lock);
422 * Called to set the hrtick timer state.
424 * called with rq->lock held and irqs disabled
426 void hrtick_start(struct rq *rq, u64 delay)
428 struct hrtimer *timer = &rq->hrtick_timer;
429 ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
431 hrtimer_set_expires(timer, time);
433 if (rq == this_rq()) {
434 __hrtick_restart(rq);
435 } else if (!rq->hrtick_csd_pending) {
436 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
437 rq->hrtick_csd_pending = 1;
442 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
444 int cpu = (int)(long)hcpu;
447 case CPU_UP_CANCELED:
448 case CPU_UP_CANCELED_FROZEN:
449 case CPU_DOWN_PREPARE:
450 case CPU_DOWN_PREPARE_FROZEN:
452 case CPU_DEAD_FROZEN:
453 hrtick_clear(cpu_rq(cpu));
460 static __init void init_hrtick(void)
462 hotcpu_notifier(hotplug_hrtick, 0);
466 * Called to set the hrtick timer state.
468 * called with rq->lock held and irqs disabled
470 void hrtick_start(struct rq *rq, u64 delay)
472 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
473 HRTIMER_MODE_REL_PINNED, 0);
476 static inline void init_hrtick(void)
479 #endif /* CONFIG_SMP */
481 static void init_rq_hrtick(struct rq *rq)
484 rq->hrtick_csd_pending = 0;
486 rq->hrtick_csd.flags = 0;
487 rq->hrtick_csd.func = __hrtick_start;
488 rq->hrtick_csd.info = rq;
491 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
492 rq->hrtick_timer.function = hrtick;
494 #else /* CONFIG_SCHED_HRTICK */
495 static inline void hrtick_clear(struct rq *rq)
499 static inline void init_rq_hrtick(struct rq *rq)
503 static inline void init_hrtick(void)
506 #endif /* CONFIG_SCHED_HRTICK */
509 * resched_task - mark a task 'to be rescheduled now'.
511 * On UP this means the setting of the need_resched flag, on SMP it
512 * might also involve a cross-CPU call to trigger the scheduler on
515 void resched_task(struct task_struct *p)
519 lockdep_assert_held(&task_rq(p)->lock);
521 if (test_tsk_need_resched(p))
524 set_tsk_need_resched(p);
527 if (cpu == smp_processor_id()) {
528 set_preempt_need_resched();
532 /* NEED_RESCHED must be visible before we test polling */
534 if (!tsk_is_polling(p))
535 smp_send_reschedule(cpu);
538 void resched_cpu(int cpu)
540 struct rq *rq = cpu_rq(cpu);
543 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
545 resched_task(cpu_curr(cpu));
546 raw_spin_unlock_irqrestore(&rq->lock, flags);
550 #ifdef CONFIG_NO_HZ_COMMON
552 * In the semi idle case, use the nearest busy cpu for migrating timers
553 * from an idle cpu. This is good for power-savings.
555 * We don't do similar optimization for completely idle system, as
556 * selecting an idle cpu will add more delays to the timers than intended
557 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
559 int get_nohz_timer_target(int pinned)
561 int cpu = smp_processor_id();
563 struct sched_domain *sd;
565 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
569 for_each_domain(cpu, sd) {
570 for_each_cpu(i, sched_domain_span(sd)) {
582 * When add_timer_on() enqueues a timer into the timer wheel of an
583 * idle CPU then this timer might expire before the next timer event
584 * which is scheduled to wake up that CPU. In case of a completely
585 * idle system the next event might even be infinite time into the
586 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
587 * leaves the inner idle loop so the newly added timer is taken into
588 * account when the CPU goes back to idle and evaluates the timer
589 * wheel for the next timer event.
591 static void wake_up_idle_cpu(int cpu)
593 struct rq *rq = cpu_rq(cpu);
595 if (cpu == smp_processor_id())
599 * This is safe, as this function is called with the timer
600 * wheel base lock of (cpu) held. When the CPU is on the way
601 * to idle and has not yet set rq->curr to idle then it will
602 * be serialized on the timer wheel base lock and take the new
603 * timer into account automatically.
605 if (rq->curr != rq->idle)
609 * We can set TIF_RESCHED on the idle task of the other CPU
610 * lockless. The worst case is that the other CPU runs the
611 * idle task through an additional NOOP schedule()
613 set_tsk_need_resched(rq->idle);
615 /* NEED_RESCHED must be visible before we test polling */
617 if (!tsk_is_polling(rq->idle))
618 smp_send_reschedule(cpu);
621 static bool wake_up_full_nohz_cpu(int cpu)
623 if (tick_nohz_full_cpu(cpu)) {
624 if (cpu != smp_processor_id() ||
625 tick_nohz_tick_stopped())
626 smp_send_reschedule(cpu);
633 void wake_up_nohz_cpu(int cpu)
635 if (!wake_up_full_nohz_cpu(cpu))
636 wake_up_idle_cpu(cpu);
639 static inline bool got_nohz_idle_kick(void)
641 int cpu = smp_processor_id();
643 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
646 if (idle_cpu(cpu) && !need_resched())
650 * We can't run Idle Load Balance on this CPU for this time so we
651 * cancel it and clear NOHZ_BALANCE_KICK
653 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
657 #else /* CONFIG_NO_HZ_COMMON */
659 static inline bool got_nohz_idle_kick(void)
664 #endif /* CONFIG_NO_HZ_COMMON */
666 #ifdef CONFIG_NO_HZ_FULL
667 bool sched_can_stop_tick(void)
673 /* Make sure rq->nr_running update is visible after the IPI */
676 /* More than one running task need preemption */
677 if (rq->nr_running > 1)
682 #endif /* CONFIG_NO_HZ_FULL */
684 void sched_avg_update(struct rq *rq)
686 s64 period = sched_avg_period();
688 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
690 * Inline assembly required to prevent the compiler
691 * optimising this loop into a divmod call.
692 * See __iter_div_u64_rem() for another example of this.
694 asm("" : "+rm" (rq->age_stamp));
695 rq->age_stamp += period;
700 #endif /* CONFIG_SMP */
702 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
703 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
705 * Iterate task_group tree rooted at *from, calling @down when first entering a
706 * node and @up when leaving it for the final time.
708 * Caller must hold rcu_lock or sufficient equivalent.
710 int walk_tg_tree_from(struct task_group *from,
711 tg_visitor down, tg_visitor up, void *data)
713 struct task_group *parent, *child;
719 ret = (*down)(parent, data);
722 list_for_each_entry_rcu(child, &parent->children, siblings) {
729 ret = (*up)(parent, data);
730 if (ret || parent == from)
734 parent = parent->parent;
741 int tg_nop(struct task_group *tg, void *data)
747 static void set_load_weight(struct task_struct *p)
749 int prio = p->static_prio - MAX_RT_PRIO;
750 struct load_weight *load = &p->se.load;
753 * SCHED_IDLE tasks get minimal weight:
755 if (p->policy == SCHED_IDLE) {
756 load->weight = scale_load(WEIGHT_IDLEPRIO);
757 load->inv_weight = WMULT_IDLEPRIO;
761 load->weight = scale_load(prio_to_weight[prio]);
762 load->inv_weight = prio_to_wmult[prio];
765 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
768 sched_info_queued(rq, p);
769 p->sched_class->enqueue_task(rq, p, flags);
772 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
775 sched_info_dequeued(rq, p);
776 p->sched_class->dequeue_task(rq, p, flags);
779 void activate_task(struct rq *rq, struct task_struct *p, int flags)
781 if (task_contributes_to_load(p))
782 rq->nr_uninterruptible--;
784 enqueue_task(rq, p, flags);
787 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
789 if (task_contributes_to_load(p))
790 rq->nr_uninterruptible++;
792 dequeue_task(rq, p, flags);
795 static void update_rq_clock_task(struct rq *rq, s64 delta)
798 * In theory, the compile should just see 0 here, and optimize out the call
799 * to sched_rt_avg_update. But I don't trust it...
801 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
802 s64 steal = 0, irq_delta = 0;
804 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
805 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
808 * Since irq_time is only updated on {soft,}irq_exit, we might run into
809 * this case when a previous update_rq_clock() happened inside a
812 * When this happens, we stop ->clock_task and only update the
813 * prev_irq_time stamp to account for the part that fit, so that a next
814 * update will consume the rest. This ensures ->clock_task is
817 * It does however cause some slight miss-attribution of {soft,}irq
818 * time, a more accurate solution would be to update the irq_time using
819 * the current rq->clock timestamp, except that would require using
822 if (irq_delta > delta)
825 rq->prev_irq_time += irq_delta;
828 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
829 if (static_key_false((¶virt_steal_rq_enabled))) {
830 steal = paravirt_steal_clock(cpu_of(rq));
831 steal -= rq->prev_steal_time_rq;
833 if (unlikely(steal > delta))
836 rq->prev_steal_time_rq += steal;
841 rq->clock_task += delta;
843 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
844 if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
845 sched_rt_avg_update(rq, irq_delta + steal);
849 void sched_set_stop_task(int cpu, struct task_struct *stop)
851 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
852 struct task_struct *old_stop = cpu_rq(cpu)->stop;
856 * Make it appear like a SCHED_FIFO task, its something
857 * userspace knows about and won't get confused about.
859 * Also, it will make PI more or less work without too
860 * much confusion -- but then, stop work should not
861 * rely on PI working anyway.
863 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
865 stop->sched_class = &stop_sched_class;
868 cpu_rq(cpu)->stop = stop;
872 * Reset it back to a normal scheduling class so that
873 * it can die in pieces.
875 old_stop->sched_class = &rt_sched_class;
880 * __normal_prio - return the priority that is based on the static prio
882 static inline int __normal_prio(struct task_struct *p)
884 return p->static_prio;
888 * Calculate the expected normal priority: i.e. priority
889 * without taking RT-inheritance into account. Might be
890 * boosted by interactivity modifiers. Changes upon fork,
891 * setprio syscalls, and whenever the interactivity
892 * estimator recalculates.
894 static inline int normal_prio(struct task_struct *p)
898 if (task_has_dl_policy(p))
899 prio = MAX_DL_PRIO-1;
900 else if (task_has_rt_policy(p))
901 prio = MAX_RT_PRIO-1 - p->rt_priority;
903 prio = __normal_prio(p);
908 * Calculate the current priority, i.e. the priority
909 * taken into account by the scheduler. This value might
910 * be boosted by RT tasks, or might be boosted by
911 * interactivity modifiers. Will be RT if the task got
912 * RT-boosted. If not then it returns p->normal_prio.
914 static int effective_prio(struct task_struct *p)
916 p->normal_prio = normal_prio(p);
918 * If we are RT tasks or we were boosted to RT priority,
919 * keep the priority unchanged. Otherwise, update priority
920 * to the normal priority:
922 if (!rt_prio(p->prio))
923 return p->normal_prio;
928 * task_curr - is this task currently executing on a CPU?
929 * @p: the task in question.
931 * Return: 1 if the task is currently executing. 0 otherwise.
933 inline int task_curr(const struct task_struct *p)
935 return cpu_curr(task_cpu(p)) == p;
938 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
939 const struct sched_class *prev_class,
942 if (prev_class != p->sched_class) {
943 if (prev_class->switched_from)
944 prev_class->switched_from(rq, p);
945 p->sched_class->switched_to(rq, p);
946 } else if (oldprio != p->prio || dl_task(p))
947 p->sched_class->prio_changed(rq, p, oldprio);
950 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
952 const struct sched_class *class;
954 if (p->sched_class == rq->curr->sched_class) {
955 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
957 for_each_class(class) {
958 if (class == rq->curr->sched_class)
960 if (class == p->sched_class) {
961 resched_task(rq->curr);
968 * A queue event has occurred, and we're going to schedule. In
969 * this case, we can save a useless back to back clock update.
971 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
972 rq->skip_clock_update = 1;
976 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
978 #ifdef CONFIG_SCHED_DEBUG
980 * We should never call set_task_cpu() on a blocked task,
981 * ttwu() will sort out the placement.
983 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
984 !(task_preempt_count(p) & PREEMPT_ACTIVE));
986 #ifdef CONFIG_LOCKDEP
988 * The caller should hold either p->pi_lock or rq->lock, when changing
989 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
991 * sched_move_task() holds both and thus holding either pins the cgroup,
994 * Furthermore, all task_rq users should acquire both locks, see
997 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
998 lockdep_is_held(&task_rq(p)->lock)));
1002 trace_sched_migrate_task(p, new_cpu);
1004 if (task_cpu(p) != new_cpu) {
1005 if (p->sched_class->migrate_task_rq)
1006 p->sched_class->migrate_task_rq(p, new_cpu);
1007 p->se.nr_migrations++;
1008 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1011 __set_task_cpu(p, new_cpu);
1014 static void __migrate_swap_task(struct task_struct *p, int cpu)
1017 struct rq *src_rq, *dst_rq;
1019 src_rq = task_rq(p);
1020 dst_rq = cpu_rq(cpu);
1022 deactivate_task(src_rq, p, 0);
1023 set_task_cpu(p, cpu);
1024 activate_task(dst_rq, p, 0);
1025 check_preempt_curr(dst_rq, p, 0);
1028 * Task isn't running anymore; make it appear like we migrated
1029 * it before it went to sleep. This means on wakeup we make the
1030 * previous cpu our targer instead of where it really is.
1036 struct migration_swap_arg {
1037 struct task_struct *src_task, *dst_task;
1038 int src_cpu, dst_cpu;
1041 static int migrate_swap_stop(void *data)
1043 struct migration_swap_arg *arg = data;
1044 struct rq *src_rq, *dst_rq;
1047 src_rq = cpu_rq(arg->src_cpu);
1048 dst_rq = cpu_rq(arg->dst_cpu);
1050 double_raw_lock(&arg->src_task->pi_lock,
1051 &arg->dst_task->pi_lock);
1052 double_rq_lock(src_rq, dst_rq);
1053 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1056 if (task_cpu(arg->src_task) != arg->src_cpu)
1059 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1062 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1065 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1066 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1071 double_rq_unlock(src_rq, dst_rq);
1072 raw_spin_unlock(&arg->dst_task->pi_lock);
1073 raw_spin_unlock(&arg->src_task->pi_lock);
1079 * Cross migrate two tasks
1081 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1083 struct migration_swap_arg arg;
1086 arg = (struct migration_swap_arg){
1088 .src_cpu = task_cpu(cur),
1090 .dst_cpu = task_cpu(p),
1093 if (arg.src_cpu == arg.dst_cpu)
1097 * These three tests are all lockless; this is OK since all of them
1098 * will be re-checked with proper locks held further down the line.
1100 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1103 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1106 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1109 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1110 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1116 struct migration_arg {
1117 struct task_struct *task;
1121 static int migration_cpu_stop(void *data);
1124 * wait_task_inactive - wait for a thread to unschedule.
1126 * If @match_state is nonzero, it's the @p->state value just checked and
1127 * not expected to change. If it changes, i.e. @p might have woken up,
1128 * then return zero. When we succeed in waiting for @p to be off its CPU,
1129 * we return a positive number (its total switch count). If a second call
1130 * a short while later returns the same number, the caller can be sure that
1131 * @p has remained unscheduled the whole time.
1133 * The caller must ensure that the task *will* unschedule sometime soon,
1134 * else this function might spin for a *long* time. This function can't
1135 * be called with interrupts off, or it may introduce deadlock with
1136 * smp_call_function() if an IPI is sent by the same process we are
1137 * waiting to become inactive.
1139 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1141 unsigned long flags;
1148 * We do the initial early heuristics without holding
1149 * any task-queue locks at all. We'll only try to get
1150 * the runqueue lock when things look like they will
1156 * If the task is actively running on another CPU
1157 * still, just relax and busy-wait without holding
1160 * NOTE! Since we don't hold any locks, it's not
1161 * even sure that "rq" stays as the right runqueue!
1162 * But we don't care, since "task_running()" will
1163 * return false if the runqueue has changed and p
1164 * is actually now running somewhere else!
1166 while (task_running(rq, p)) {
1167 if (match_state && unlikely(p->state != match_state))
1173 * Ok, time to look more closely! We need the rq
1174 * lock now, to be *sure*. If we're wrong, we'll
1175 * just go back and repeat.
1177 rq = task_rq_lock(p, &flags);
1178 trace_sched_wait_task(p);
1179 running = task_running(rq, p);
1182 if (!match_state || p->state == match_state)
1183 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1184 task_rq_unlock(rq, p, &flags);
1187 * If it changed from the expected state, bail out now.
1189 if (unlikely(!ncsw))
1193 * Was it really running after all now that we
1194 * checked with the proper locks actually held?
1196 * Oops. Go back and try again..
1198 if (unlikely(running)) {
1204 * It's not enough that it's not actively running,
1205 * it must be off the runqueue _entirely_, and not
1208 * So if it was still runnable (but just not actively
1209 * running right now), it's preempted, and we should
1210 * yield - it could be a while.
1212 if (unlikely(on_rq)) {
1213 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1215 set_current_state(TASK_UNINTERRUPTIBLE);
1216 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1221 * Ahh, all good. It wasn't running, and it wasn't
1222 * runnable, which means that it will never become
1223 * running in the future either. We're all done!
1232 * kick_process - kick a running thread to enter/exit the kernel
1233 * @p: the to-be-kicked thread
1235 * Cause a process which is running on another CPU to enter
1236 * kernel-mode, without any delay. (to get signals handled.)
1238 * NOTE: this function doesn't have to take the runqueue lock,
1239 * because all it wants to ensure is that the remote task enters
1240 * the kernel. If the IPI races and the task has been migrated
1241 * to another CPU then no harm is done and the purpose has been
1244 void kick_process(struct task_struct *p)
1250 if ((cpu != smp_processor_id()) && task_curr(p))
1251 smp_send_reschedule(cpu);
1254 EXPORT_SYMBOL_GPL(kick_process);
1255 #endif /* CONFIG_SMP */
1259 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1261 static int select_fallback_rq(int cpu, struct task_struct *p)
1263 int nid = cpu_to_node(cpu);
1264 const struct cpumask *nodemask = NULL;
1265 enum { cpuset, possible, fail } state = cpuset;
1269 * If the node that the cpu is on has been offlined, cpu_to_node()
1270 * will return -1. There is no cpu on the node, and we should
1271 * select the cpu on the other node.
1274 nodemask = cpumask_of_node(nid);
1276 /* Look for allowed, online CPU in same node. */
1277 for_each_cpu(dest_cpu, nodemask) {
1278 if (!cpu_online(dest_cpu))
1280 if (!cpu_active(dest_cpu))
1282 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1288 /* Any allowed, online CPU? */
1289 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1290 if (!cpu_online(dest_cpu))
1292 if (!cpu_active(dest_cpu))
1299 /* No more Mr. Nice Guy. */
1300 cpuset_cpus_allowed_fallback(p);
1305 do_set_cpus_allowed(p, cpu_possible_mask);
1316 if (state != cpuset) {
1318 * Don't tell them about moving exiting tasks or
1319 * kernel threads (both mm NULL), since they never
1322 if (p->mm && printk_ratelimit()) {
1323 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1324 task_pid_nr(p), p->comm, cpu);
1332 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1335 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1337 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1340 * In order not to call set_task_cpu() on a blocking task we need
1341 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1344 * Since this is common to all placement strategies, this lives here.
1346 * [ this allows ->select_task() to simply return task_cpu(p) and
1347 * not worry about this generic constraint ]
1349 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1351 cpu = select_fallback_rq(task_cpu(p), p);
1356 static void update_avg(u64 *avg, u64 sample)
1358 s64 diff = sample - *avg;
1364 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1366 #ifdef CONFIG_SCHEDSTATS
1367 struct rq *rq = this_rq();
1370 int this_cpu = smp_processor_id();
1372 if (cpu == this_cpu) {
1373 schedstat_inc(rq, ttwu_local);
1374 schedstat_inc(p, se.statistics.nr_wakeups_local);
1376 struct sched_domain *sd;
1378 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1380 for_each_domain(this_cpu, sd) {
1381 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1382 schedstat_inc(sd, ttwu_wake_remote);
1389 if (wake_flags & WF_MIGRATED)
1390 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1392 #endif /* CONFIG_SMP */
1394 schedstat_inc(rq, ttwu_count);
1395 schedstat_inc(p, se.statistics.nr_wakeups);
1397 if (wake_flags & WF_SYNC)
1398 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1400 #endif /* CONFIG_SCHEDSTATS */
1403 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1405 activate_task(rq, p, en_flags);
1408 /* if a worker is waking up, notify workqueue */
1409 if (p->flags & PF_WQ_WORKER)
1410 wq_worker_waking_up(p, cpu_of(rq));
1414 * Mark the task runnable and perform wakeup-preemption.
1417 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1419 check_preempt_curr(rq, p, wake_flags);
1420 trace_sched_wakeup(p, true);
1422 p->state = TASK_RUNNING;
1424 if (p->sched_class->task_woken)
1425 p->sched_class->task_woken(rq, p);
1427 if (rq->idle_stamp) {
1428 u64 delta = rq_clock(rq) - rq->idle_stamp;
1429 u64 max = 2*rq->max_idle_balance_cost;
1431 update_avg(&rq->avg_idle, delta);
1433 if (rq->avg_idle > max)
1442 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1445 if (p->sched_contributes_to_load)
1446 rq->nr_uninterruptible--;
1449 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1450 ttwu_do_wakeup(rq, p, wake_flags);
1454 * Called in case the task @p isn't fully descheduled from its runqueue,
1455 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1456 * since all we need to do is flip p->state to TASK_RUNNING, since
1457 * the task is still ->on_rq.
1459 static int ttwu_remote(struct task_struct *p, int wake_flags)
1464 rq = __task_rq_lock(p);
1466 /* check_preempt_curr() may use rq clock */
1467 update_rq_clock(rq);
1468 ttwu_do_wakeup(rq, p, wake_flags);
1471 __task_rq_unlock(rq);
1477 static void sched_ttwu_pending(void)
1479 struct rq *rq = this_rq();
1480 struct llist_node *llist = llist_del_all(&rq->wake_list);
1481 struct task_struct *p;
1483 raw_spin_lock(&rq->lock);
1486 p = llist_entry(llist, struct task_struct, wake_entry);
1487 llist = llist_next(llist);
1488 ttwu_do_activate(rq, p, 0);
1491 raw_spin_unlock(&rq->lock);
1494 void scheduler_ipi(void)
1497 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1498 * TIF_NEED_RESCHED remotely (for the first time) will also send
1501 preempt_fold_need_resched();
1503 if (llist_empty(&this_rq()->wake_list)
1504 && !tick_nohz_full_cpu(smp_processor_id())
1505 && !got_nohz_idle_kick())
1509 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1510 * traditionally all their work was done from the interrupt return
1511 * path. Now that we actually do some work, we need to make sure
1514 * Some archs already do call them, luckily irq_enter/exit nest
1517 * Arguably we should visit all archs and update all handlers,
1518 * however a fair share of IPIs are still resched only so this would
1519 * somewhat pessimize the simple resched case.
1522 tick_nohz_full_check();
1523 sched_ttwu_pending();
1526 * Check if someone kicked us for doing the nohz idle load balance.
1528 if (unlikely(got_nohz_idle_kick())) {
1529 this_rq()->idle_balance = 1;
1530 raise_softirq_irqoff(SCHED_SOFTIRQ);
1535 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1537 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
1538 smp_send_reschedule(cpu);
1541 bool cpus_share_cache(int this_cpu, int that_cpu)
1543 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1545 #endif /* CONFIG_SMP */
1547 static void ttwu_queue(struct task_struct *p, int cpu)
1549 struct rq *rq = cpu_rq(cpu);
1551 #if defined(CONFIG_SMP)
1552 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1553 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1554 ttwu_queue_remote(p, cpu);
1559 raw_spin_lock(&rq->lock);
1560 ttwu_do_activate(rq, p, 0);
1561 raw_spin_unlock(&rq->lock);
1565 * try_to_wake_up - wake up a thread
1566 * @p: the thread to be awakened
1567 * @state: the mask of task states that can be woken
1568 * @wake_flags: wake modifier flags (WF_*)
1570 * Put it on the run-queue if it's not already there. The "current"
1571 * thread is always on the run-queue (except when the actual
1572 * re-schedule is in progress), and as such you're allowed to do
1573 * the simpler "current->state = TASK_RUNNING" to mark yourself
1574 * runnable without the overhead of this.
1576 * Return: %true if @p was woken up, %false if it was already running.
1577 * or @state didn't match @p's state.
1580 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1582 unsigned long flags;
1583 int cpu, success = 0;
1586 * If we are going to wake up a thread waiting for CONDITION we
1587 * need to ensure that CONDITION=1 done by the caller can not be
1588 * reordered with p->state check below. This pairs with mb() in
1589 * set_current_state() the waiting thread does.
1591 smp_mb__before_spinlock();
1592 raw_spin_lock_irqsave(&p->pi_lock, flags);
1593 if (!(p->state & state))
1596 success = 1; /* we're going to change ->state */
1599 if (p->on_rq && ttwu_remote(p, wake_flags))
1604 * If the owning (remote) cpu is still in the middle of schedule() with
1605 * this task as prev, wait until its done referencing the task.
1610 * Pairs with the smp_wmb() in finish_lock_switch().
1614 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1615 p->state = TASK_WAKING;
1617 if (p->sched_class->task_waking)
1618 p->sched_class->task_waking(p);
1620 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1621 if (task_cpu(p) != cpu) {
1622 wake_flags |= WF_MIGRATED;
1623 set_task_cpu(p, cpu);
1625 #endif /* CONFIG_SMP */
1629 ttwu_stat(p, cpu, wake_flags);
1631 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1637 * try_to_wake_up_local - try to wake up a local task with rq lock held
1638 * @p: the thread to be awakened
1640 * Put @p on the run-queue if it's not already there. The caller must
1641 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1644 static void try_to_wake_up_local(struct task_struct *p)
1646 struct rq *rq = task_rq(p);
1648 if (WARN_ON_ONCE(rq != this_rq()) ||
1649 WARN_ON_ONCE(p == current))
1652 lockdep_assert_held(&rq->lock);
1654 if (!raw_spin_trylock(&p->pi_lock)) {
1655 raw_spin_unlock(&rq->lock);
1656 raw_spin_lock(&p->pi_lock);
1657 raw_spin_lock(&rq->lock);
1660 if (!(p->state & TASK_NORMAL))
1664 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1666 ttwu_do_wakeup(rq, p, 0);
1667 ttwu_stat(p, smp_processor_id(), 0);
1669 raw_spin_unlock(&p->pi_lock);
1673 * wake_up_process - Wake up a specific process
1674 * @p: The process to be woken up.
1676 * Attempt to wake up the nominated process and move it to the set of runnable
1679 * Return: 1 if the process was woken up, 0 if it was already running.
1681 * It may be assumed that this function implies a write memory barrier before
1682 * changing the task state if and only if any tasks are woken up.
1684 int wake_up_process(struct task_struct *p)
1686 WARN_ON(task_is_stopped_or_traced(p));
1687 return try_to_wake_up(p, TASK_NORMAL, 0);
1689 EXPORT_SYMBOL(wake_up_process);
1691 int wake_up_state(struct task_struct *p, unsigned int state)
1693 return try_to_wake_up(p, state, 0);
1697 * Perform scheduler related setup for a newly forked process p.
1698 * p is forked by current.
1700 * __sched_fork() is basic setup used by init_idle() too:
1702 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1707 p->se.exec_start = 0;
1708 p->se.sum_exec_runtime = 0;
1709 p->se.prev_sum_exec_runtime = 0;
1710 p->se.nr_migrations = 0;
1712 INIT_LIST_HEAD(&p->se.group_node);
1714 #ifdef CONFIG_SCHEDSTATS
1715 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1718 RB_CLEAR_NODE(&p->dl.rb_node);
1719 hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1720 p->dl.dl_runtime = p->dl.runtime = 0;
1721 p->dl.dl_deadline = p->dl.deadline = 0;
1722 p->dl.dl_period = 0;
1725 INIT_LIST_HEAD(&p->rt.run_list);
1727 #ifdef CONFIG_PREEMPT_NOTIFIERS
1728 INIT_HLIST_HEAD(&p->preempt_notifiers);
1731 #ifdef CONFIG_NUMA_BALANCING
1732 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1733 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1734 p->mm->numa_scan_seq = 0;
1737 if (clone_flags & CLONE_VM)
1738 p->numa_preferred_nid = current->numa_preferred_nid;
1740 p->numa_preferred_nid = -1;
1742 p->node_stamp = 0ULL;
1743 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1744 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1745 p->numa_work.next = &p->numa_work;
1746 p->numa_faults_memory = NULL;
1747 p->numa_faults_buffer_memory = NULL;
1748 p->last_task_numa_placement = 0;
1749 p->last_sum_exec_runtime = 0;
1751 INIT_LIST_HEAD(&p->numa_entry);
1752 p->numa_group = NULL;
1753 #endif /* CONFIG_NUMA_BALANCING */
1756 #ifdef CONFIG_NUMA_BALANCING
1757 #ifdef CONFIG_SCHED_DEBUG
1758 void set_numabalancing_state(bool enabled)
1761 sched_feat_set("NUMA");
1763 sched_feat_set("NO_NUMA");
1766 __read_mostly bool numabalancing_enabled;
1768 void set_numabalancing_state(bool enabled)
1770 numabalancing_enabled = enabled;
1772 #endif /* CONFIG_SCHED_DEBUG */
1774 #ifdef CONFIG_PROC_SYSCTL
1775 int sysctl_numa_balancing(struct ctl_table *table, int write,
1776 void __user *buffer, size_t *lenp, loff_t *ppos)
1780 int state = numabalancing_enabled;
1782 if (write && !capable(CAP_SYS_ADMIN))
1787 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
1791 set_numabalancing_state(state);
1798 * fork()/clone()-time setup:
1800 int sched_fork(unsigned long clone_flags, struct task_struct *p)
1802 unsigned long flags;
1803 int cpu = get_cpu();
1805 __sched_fork(clone_flags, p);
1807 * We mark the process as running here. This guarantees that
1808 * nobody will actually run it, and a signal or other external
1809 * event cannot wake it up and insert it on the runqueue either.
1811 p->state = TASK_RUNNING;
1814 * Make sure we do not leak PI boosting priority to the child.
1816 p->prio = current->normal_prio;
1819 * Revert to default priority/policy on fork if requested.
1821 if (unlikely(p->sched_reset_on_fork)) {
1822 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
1823 p->policy = SCHED_NORMAL;
1824 p->static_prio = NICE_TO_PRIO(0);
1826 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1827 p->static_prio = NICE_TO_PRIO(0);
1829 p->prio = p->normal_prio = __normal_prio(p);
1833 * We don't need the reset flag anymore after the fork. It has
1834 * fulfilled its duty:
1836 p->sched_reset_on_fork = 0;
1839 if (dl_prio(p->prio)) {
1842 } else if (rt_prio(p->prio)) {
1843 p->sched_class = &rt_sched_class;
1845 p->sched_class = &fair_sched_class;
1848 if (p->sched_class->task_fork)
1849 p->sched_class->task_fork(p);
1852 * The child is not yet in the pid-hash so no cgroup attach races,
1853 * and the cgroup is pinned to this child due to cgroup_fork()
1854 * is ran before sched_fork().
1856 * Silence PROVE_RCU.
1858 raw_spin_lock_irqsave(&p->pi_lock, flags);
1859 set_task_cpu(p, cpu);
1860 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1862 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1863 if (likely(sched_info_on()))
1864 memset(&p->sched_info, 0, sizeof(p->sched_info));
1866 #if defined(CONFIG_SMP)
1869 init_task_preempt_count(p);
1871 plist_node_init(&p->pushable_tasks, MAX_PRIO);
1872 RB_CLEAR_NODE(&p->pushable_dl_tasks);
1879 unsigned long to_ratio(u64 period, u64 runtime)
1881 if (runtime == RUNTIME_INF)
1885 * Doing this here saves a lot of checks in all
1886 * the calling paths, and returning zero seems
1887 * safe for them anyway.
1892 return div64_u64(runtime << 20, period);
1896 inline struct dl_bw *dl_bw_of(int i)
1898 return &cpu_rq(i)->rd->dl_bw;
1901 static inline int dl_bw_cpus(int i)
1903 struct root_domain *rd = cpu_rq(i)->rd;
1906 for_each_cpu_and(i, rd->span, cpu_active_mask)
1912 inline struct dl_bw *dl_bw_of(int i)
1914 return &cpu_rq(i)->dl.dl_bw;
1917 static inline int dl_bw_cpus(int i)
1924 void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw)
1926 dl_b->total_bw -= tsk_bw;
1930 void __dl_add(struct dl_bw *dl_b, u64 tsk_bw)
1932 dl_b->total_bw += tsk_bw;
1936 bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
1938 return dl_b->bw != -1 &&
1939 dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
1943 * We must be sure that accepting a new task (or allowing changing the
1944 * parameters of an existing one) is consistent with the bandwidth
1945 * constraints. If yes, this function also accordingly updates the currently
1946 * allocated bandwidth to reflect the new situation.
1948 * This function is called while holding p's rq->lock.
1950 static int dl_overflow(struct task_struct *p, int policy,
1951 const struct sched_attr *attr)
1954 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
1955 u64 period = attr->sched_period ?: attr->sched_deadline;
1956 u64 runtime = attr->sched_runtime;
1957 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
1960 if (new_bw == p->dl.dl_bw)
1964 * Either if a task, enters, leave, or stays -deadline but changes
1965 * its parameters, we may need to update accordingly the total
1966 * allocated bandwidth of the container.
1968 raw_spin_lock(&dl_b->lock);
1969 cpus = dl_bw_cpus(task_cpu(p));
1970 if (dl_policy(policy) && !task_has_dl_policy(p) &&
1971 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
1972 __dl_add(dl_b, new_bw);
1974 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
1975 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
1976 __dl_clear(dl_b, p->dl.dl_bw);
1977 __dl_add(dl_b, new_bw);
1979 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
1980 __dl_clear(dl_b, p->dl.dl_bw);
1983 raw_spin_unlock(&dl_b->lock);
1988 extern void init_dl_bw(struct dl_bw *dl_b);
1991 * wake_up_new_task - wake up a newly created task for the first time.
1993 * This function will do some initial scheduler statistics housekeeping
1994 * that must be done for every newly created context, then puts the task
1995 * on the runqueue and wakes it.
1997 void wake_up_new_task(struct task_struct *p)
1999 unsigned long flags;
2002 raw_spin_lock_irqsave(&p->pi_lock, flags);
2005 * Fork balancing, do it here and not earlier because:
2006 * - cpus_allowed can change in the fork path
2007 * - any previously selected cpu might disappear through hotplug
2009 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2012 /* Initialize new task's runnable average */
2013 init_task_runnable_average(p);
2014 rq = __task_rq_lock(p);
2015 activate_task(rq, p, 0);
2017 trace_sched_wakeup_new(p, true);
2018 check_preempt_curr(rq, p, WF_FORK);
2020 if (p->sched_class->task_woken)
2021 p->sched_class->task_woken(rq, p);
2023 task_rq_unlock(rq, p, &flags);
2026 #ifdef CONFIG_PREEMPT_NOTIFIERS
2029 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2030 * @notifier: notifier struct to register
2032 void preempt_notifier_register(struct preempt_notifier *notifier)
2034 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2036 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2039 * preempt_notifier_unregister - no longer interested in preemption notifications
2040 * @notifier: notifier struct to unregister
2042 * This is safe to call from within a preemption notifier.
2044 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2046 hlist_del(¬ifier->link);
2048 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2050 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2052 struct preempt_notifier *notifier;
2054 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2055 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2059 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2060 struct task_struct *next)
2062 struct preempt_notifier *notifier;
2064 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2065 notifier->ops->sched_out(notifier, next);
2068 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2070 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2075 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2076 struct task_struct *next)
2080 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2083 * prepare_task_switch - prepare to switch tasks
2084 * @rq: the runqueue preparing to switch
2085 * @prev: the current task that is being switched out
2086 * @next: the task we are going to switch to.
2088 * This is called with the rq lock held and interrupts off. It must
2089 * be paired with a subsequent finish_task_switch after the context
2092 * prepare_task_switch sets up locking and calls architecture specific
2096 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2097 struct task_struct *next)
2099 trace_sched_switch(prev, next);
2100 sched_info_switch(rq, prev, next);
2101 perf_event_task_sched_out(prev, next);
2102 fire_sched_out_preempt_notifiers(prev, next);
2103 prepare_lock_switch(rq, next);
2104 prepare_arch_switch(next);
2108 * finish_task_switch - clean up after a task-switch
2109 * @rq: runqueue associated with task-switch
2110 * @prev: the thread we just switched away from.
2112 * finish_task_switch must be called after the context switch, paired
2113 * with a prepare_task_switch call before the context switch.
2114 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2115 * and do any other architecture-specific cleanup actions.
2117 * Note that we may have delayed dropping an mm in context_switch(). If
2118 * so, we finish that here outside of the runqueue lock. (Doing it
2119 * with the lock held can cause deadlocks; see schedule() for
2122 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2123 __releases(rq->lock)
2125 struct mm_struct *mm = rq->prev_mm;
2131 * A task struct has one reference for the use as "current".
2132 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2133 * schedule one last time. The schedule call will never return, and
2134 * the scheduled task must drop that reference.
2135 * The test for TASK_DEAD must occur while the runqueue locks are
2136 * still held, otherwise prev could be scheduled on another cpu, die
2137 * there before we look at prev->state, and then the reference would
2139 * Manfred Spraul <manfred@colorfullife.com>
2141 prev_state = prev->state;
2142 vtime_task_switch(prev);
2143 finish_arch_switch(prev);
2144 perf_event_task_sched_in(prev, current);
2145 finish_lock_switch(rq, prev);
2146 finish_arch_post_lock_switch();
2148 fire_sched_in_preempt_notifiers(current);
2151 if (unlikely(prev_state == TASK_DEAD)) {
2152 if (prev->sched_class->task_dead)
2153 prev->sched_class->task_dead(prev);
2156 * Remove function-return probe instances associated with this
2157 * task and put them back on the free list.
2159 kprobe_flush_task(prev);
2160 put_task_struct(prev);
2163 tick_nohz_task_switch(current);
2168 /* rq->lock is NOT held, but preemption is disabled */
2169 static inline void post_schedule(struct rq *rq)
2171 if (rq->post_schedule) {
2172 unsigned long flags;
2174 raw_spin_lock_irqsave(&rq->lock, flags);
2175 if (rq->curr->sched_class->post_schedule)
2176 rq->curr->sched_class->post_schedule(rq);
2177 raw_spin_unlock_irqrestore(&rq->lock, flags);
2179 rq->post_schedule = 0;
2185 static inline void post_schedule(struct rq *rq)
2192 * schedule_tail - first thing a freshly forked thread must call.
2193 * @prev: the thread we just switched away from.
2195 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2196 __releases(rq->lock)
2198 struct rq *rq = this_rq();
2200 finish_task_switch(rq, prev);
2203 * FIXME: do we need to worry about rq being invalidated by the
2208 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2209 /* In this case, finish_task_switch does not reenable preemption */
2212 if (current->set_child_tid)
2213 put_user(task_pid_vnr(current), current->set_child_tid);
2217 * context_switch - switch to the new MM and the new
2218 * thread's register state.
2221 context_switch(struct rq *rq, struct task_struct *prev,
2222 struct task_struct *next)
2224 struct mm_struct *mm, *oldmm;
2226 prepare_task_switch(rq, prev, next);
2229 oldmm = prev->active_mm;
2231 * For paravirt, this is coupled with an exit in switch_to to
2232 * combine the page table reload and the switch backend into
2235 arch_start_context_switch(prev);
2238 next->active_mm = oldmm;
2239 atomic_inc(&oldmm->mm_count);
2240 enter_lazy_tlb(oldmm, next);
2242 switch_mm(oldmm, mm, next);
2245 prev->active_mm = NULL;
2246 rq->prev_mm = oldmm;
2249 * Since the runqueue lock will be released by the next
2250 * task (which is an invalid locking op but in the case
2251 * of the scheduler it's an obvious special-case), so we
2252 * do an early lockdep release here:
2254 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2255 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2258 context_tracking_task_switch(prev, next);
2259 /* Here we just switch the register state and the stack. */
2260 switch_to(prev, next, prev);
2264 * this_rq must be evaluated again because prev may have moved
2265 * CPUs since it called schedule(), thus the 'rq' on its stack
2266 * frame will be invalid.
2268 finish_task_switch(this_rq(), prev);
2272 * nr_running and nr_context_switches:
2274 * externally visible scheduler statistics: current number of runnable
2275 * threads, total number of context switches performed since bootup.
2277 unsigned long nr_running(void)
2279 unsigned long i, sum = 0;
2281 for_each_online_cpu(i)
2282 sum += cpu_rq(i)->nr_running;
2287 unsigned long long nr_context_switches(void)
2290 unsigned long long sum = 0;
2292 for_each_possible_cpu(i)
2293 sum += cpu_rq(i)->nr_switches;
2298 unsigned long nr_iowait(void)
2300 unsigned long i, sum = 0;
2302 for_each_possible_cpu(i)
2303 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2308 unsigned long nr_iowait_cpu(int cpu)
2310 struct rq *this = cpu_rq(cpu);
2311 return atomic_read(&this->nr_iowait);
2317 * sched_exec - execve() is a valuable balancing opportunity, because at
2318 * this point the task has the smallest effective memory and cache footprint.
2320 void sched_exec(void)
2322 struct task_struct *p = current;
2323 unsigned long flags;
2326 raw_spin_lock_irqsave(&p->pi_lock, flags);
2327 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2328 if (dest_cpu == smp_processor_id())
2331 if (likely(cpu_active(dest_cpu))) {
2332 struct migration_arg arg = { p, dest_cpu };
2334 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2335 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2339 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2344 DEFINE_PER_CPU(struct kernel_stat, kstat);
2345 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2347 EXPORT_PER_CPU_SYMBOL(kstat);
2348 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2351 * Return any ns on the sched_clock that have not yet been accounted in
2352 * @p in case that task is currently running.
2354 * Called with task_rq_lock() held on @rq.
2356 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2360 if (task_current(rq, p)) {
2361 update_rq_clock(rq);
2362 ns = rq_clock_task(rq) - p->se.exec_start;
2370 unsigned long long task_delta_exec(struct task_struct *p)
2372 unsigned long flags;
2376 rq = task_rq_lock(p, &flags);
2377 ns = do_task_delta_exec(p, rq);
2378 task_rq_unlock(rq, p, &flags);
2384 * Return accounted runtime for the task.
2385 * In case the task is currently running, return the runtime plus current's
2386 * pending runtime that have not been accounted yet.
2388 unsigned long long task_sched_runtime(struct task_struct *p)
2390 unsigned long flags;
2394 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2396 * 64-bit doesn't need locks to atomically read a 64bit value.
2397 * So we have a optimization chance when the task's delta_exec is 0.
2398 * Reading ->on_cpu is racy, but this is ok.
2400 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2401 * If we race with it entering cpu, unaccounted time is 0. This is
2402 * indistinguishable from the read occurring a few cycles earlier.
2405 return p->se.sum_exec_runtime;
2408 rq = task_rq_lock(p, &flags);
2409 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2410 task_rq_unlock(rq, p, &flags);
2416 * This function gets called by the timer code, with HZ frequency.
2417 * We call it with interrupts disabled.
2419 void scheduler_tick(void)
2421 int cpu = smp_processor_id();
2422 struct rq *rq = cpu_rq(cpu);
2423 struct task_struct *curr = rq->curr;
2427 raw_spin_lock(&rq->lock);
2428 update_rq_clock(rq);
2429 curr->sched_class->task_tick(rq, curr, 0);
2430 update_cpu_load_active(rq);
2431 raw_spin_unlock(&rq->lock);
2433 perf_event_task_tick();
2436 rq->idle_balance = idle_cpu(cpu);
2437 trigger_load_balance(rq);
2439 rq_last_tick_reset(rq);
2442 #ifdef CONFIG_NO_HZ_FULL
2444 * scheduler_tick_max_deferment
2446 * Keep at least one tick per second when a single
2447 * active task is running because the scheduler doesn't
2448 * yet completely support full dynticks environment.
2450 * This makes sure that uptime, CFS vruntime, load
2451 * balancing, etc... continue to move forward, even
2452 * with a very low granularity.
2454 * Return: Maximum deferment in nanoseconds.
2456 u64 scheduler_tick_max_deferment(void)
2458 struct rq *rq = this_rq();
2459 unsigned long next, now = ACCESS_ONCE(jiffies);
2461 next = rq->last_sched_tick + HZ;
2463 if (time_before_eq(next, now))
2466 return jiffies_to_nsecs(next - now);
2470 notrace unsigned long get_parent_ip(unsigned long addr)
2472 if (in_lock_functions(addr)) {
2473 addr = CALLER_ADDR2;
2474 if (in_lock_functions(addr))
2475 addr = CALLER_ADDR3;
2480 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2481 defined(CONFIG_PREEMPT_TRACER))
2483 void __kprobes preempt_count_add(int val)
2485 #ifdef CONFIG_DEBUG_PREEMPT
2489 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2492 __preempt_count_add(val);
2493 #ifdef CONFIG_DEBUG_PREEMPT
2495 * Spinlock count overflowing soon?
2497 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2500 if (preempt_count() == val) {
2501 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2502 #ifdef CONFIG_DEBUG_PREEMPT
2503 current->preempt_disable_ip = ip;
2505 trace_preempt_off(CALLER_ADDR0, ip);
2508 EXPORT_SYMBOL(preempt_count_add);
2510 void __kprobes preempt_count_sub(int val)
2512 #ifdef CONFIG_DEBUG_PREEMPT
2516 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2519 * Is the spinlock portion underflowing?
2521 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2522 !(preempt_count() & PREEMPT_MASK)))
2526 if (preempt_count() == val)
2527 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2528 __preempt_count_sub(val);
2530 EXPORT_SYMBOL(preempt_count_sub);
2535 * Print scheduling while atomic bug:
2537 static noinline void __schedule_bug(struct task_struct *prev)
2539 if (oops_in_progress)
2542 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2543 prev->comm, prev->pid, preempt_count());
2545 debug_show_held_locks(prev);
2547 if (irqs_disabled())
2548 print_irqtrace_events(prev);
2549 #ifdef CONFIG_DEBUG_PREEMPT
2550 if (in_atomic_preempt_off()) {
2551 pr_err("Preemption disabled at:");
2552 print_ip_sym(current->preempt_disable_ip);
2557 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2561 * Various schedule()-time debugging checks and statistics:
2563 static inline void schedule_debug(struct task_struct *prev)
2566 * Test if we are atomic. Since do_exit() needs to call into
2567 * schedule() atomically, we ignore that path. Otherwise whine
2568 * if we are scheduling when we should not.
2570 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
2571 __schedule_bug(prev);
2574 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2576 schedstat_inc(this_rq(), sched_count);
2580 * Pick up the highest-prio task:
2582 static inline struct task_struct *
2583 pick_next_task(struct rq *rq, struct task_struct *prev)
2585 const struct sched_class *class = &fair_sched_class;
2586 struct task_struct *p;
2589 * Optimization: we know that if all tasks are in
2590 * the fair class we can call that function directly:
2592 if (likely(prev->sched_class == class &&
2593 rq->nr_running == rq->cfs.h_nr_running)) {
2594 p = fair_sched_class.pick_next_task(rq, prev);
2595 if (unlikely(p == RETRY_TASK))
2598 /* assumes fair_sched_class->next == idle_sched_class */
2600 p = idle_sched_class.pick_next_task(rq, prev);
2606 for_each_class(class) {
2607 p = class->pick_next_task(rq, prev);
2609 if (unlikely(p == RETRY_TASK))
2615 BUG(); /* the idle class will always have a runnable task */
2619 * __schedule() is the main scheduler function.
2621 * The main means of driving the scheduler and thus entering this function are:
2623 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2625 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2626 * paths. For example, see arch/x86/entry_64.S.
2628 * To drive preemption between tasks, the scheduler sets the flag in timer
2629 * interrupt handler scheduler_tick().
2631 * 3. Wakeups don't really cause entry into schedule(). They add a
2632 * task to the run-queue and that's it.
2634 * Now, if the new task added to the run-queue preempts the current
2635 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2636 * called on the nearest possible occasion:
2638 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2640 * - in syscall or exception context, at the next outmost
2641 * preempt_enable(). (this might be as soon as the wake_up()'s
2644 * - in IRQ context, return from interrupt-handler to
2645 * preemptible context
2647 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2650 * - cond_resched() call
2651 * - explicit schedule() call
2652 * - return from syscall or exception to user-space
2653 * - return from interrupt-handler to user-space
2655 static void __sched __schedule(void)
2657 struct task_struct *prev, *next;
2658 unsigned long *switch_count;
2664 cpu = smp_processor_id();
2666 rcu_note_context_switch(cpu);
2669 schedule_debug(prev);
2671 if (sched_feat(HRTICK))
2675 * Make sure that signal_pending_state()->signal_pending() below
2676 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2677 * done by the caller to avoid the race with signal_wake_up().
2679 smp_mb__before_spinlock();
2680 raw_spin_lock_irq(&rq->lock);
2682 switch_count = &prev->nivcsw;
2683 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2684 if (unlikely(signal_pending_state(prev->state, prev))) {
2685 prev->state = TASK_RUNNING;
2687 deactivate_task(rq, prev, DEQUEUE_SLEEP);
2691 * If a worker went to sleep, notify and ask workqueue
2692 * whether it wants to wake up a task to maintain
2695 if (prev->flags & PF_WQ_WORKER) {
2696 struct task_struct *to_wakeup;
2698 to_wakeup = wq_worker_sleeping(prev, cpu);
2700 try_to_wake_up_local(to_wakeup);
2703 switch_count = &prev->nvcsw;
2706 if (prev->on_rq || rq->skip_clock_update < 0)
2707 update_rq_clock(rq);
2709 next = pick_next_task(rq, prev);
2710 clear_tsk_need_resched(prev);
2711 clear_preempt_need_resched();
2712 rq->skip_clock_update = 0;
2714 if (likely(prev != next)) {
2719 context_switch(rq, prev, next); /* unlocks the rq */
2721 * The context switch have flipped the stack from under us
2722 * and restored the local variables which were saved when
2723 * this task called schedule() in the past. prev == current
2724 * is still correct, but it can be moved to another cpu/rq.
2726 cpu = smp_processor_id();
2729 raw_spin_unlock_irq(&rq->lock);
2733 sched_preempt_enable_no_resched();
2738 static inline void sched_submit_work(struct task_struct *tsk)
2740 if (!tsk->state || tsk_is_pi_blocked(tsk))
2743 * If we are going to sleep and we have plugged IO queued,
2744 * make sure to submit it to avoid deadlocks.
2746 if (blk_needs_flush_plug(tsk))
2747 blk_schedule_flush_plug(tsk);
2750 asmlinkage __visible void __sched schedule(void)
2752 struct task_struct *tsk = current;
2754 sched_submit_work(tsk);
2757 EXPORT_SYMBOL(schedule);
2759 #ifdef CONFIG_CONTEXT_TRACKING
2760 asmlinkage __visible void __sched schedule_user(void)
2763 * If we come here after a random call to set_need_resched(),
2764 * or we have been woken up remotely but the IPI has not yet arrived,
2765 * we haven't yet exited the RCU idle mode. Do it here manually until
2766 * we find a better solution.
2775 * schedule_preempt_disabled - called with preemption disabled
2777 * Returns with preemption disabled. Note: preempt_count must be 1
2779 void __sched schedule_preempt_disabled(void)
2781 sched_preempt_enable_no_resched();
2786 #ifdef CONFIG_PREEMPT
2788 * this is the entry point to schedule() from in-kernel preemption
2789 * off of preempt_enable. Kernel preemptions off return from interrupt
2790 * occur there and call schedule directly.
2792 asmlinkage __visible void __sched notrace preempt_schedule(void)
2795 * If there is a non-zero preempt_count or interrupts are disabled,
2796 * we do not want to preempt the current task. Just return..
2798 if (likely(!preemptible()))
2802 __preempt_count_add(PREEMPT_ACTIVE);
2804 __preempt_count_sub(PREEMPT_ACTIVE);
2807 * Check again in case we missed a preemption opportunity
2808 * between schedule and now.
2811 } while (need_resched());
2813 EXPORT_SYMBOL(preempt_schedule);
2814 #endif /* CONFIG_PREEMPT */
2817 * this is the entry point to schedule() from kernel preemption
2818 * off of irq context.
2819 * Note, that this is called and return with irqs disabled. This will
2820 * protect us against recursive calling from irq.
2822 asmlinkage __visible void __sched preempt_schedule_irq(void)
2824 enum ctx_state prev_state;
2826 /* Catch callers which need to be fixed */
2827 BUG_ON(preempt_count() || !irqs_disabled());
2829 prev_state = exception_enter();
2832 __preempt_count_add(PREEMPT_ACTIVE);
2835 local_irq_disable();
2836 __preempt_count_sub(PREEMPT_ACTIVE);
2839 * Check again in case we missed a preemption opportunity
2840 * between schedule and now.
2843 } while (need_resched());
2845 exception_exit(prev_state);
2848 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2851 return try_to_wake_up(curr->private, mode, wake_flags);
2853 EXPORT_SYMBOL(default_wake_function);
2855 #ifdef CONFIG_RT_MUTEXES
2858 * rt_mutex_setprio - set the current priority of a task
2860 * @prio: prio value (kernel-internal form)
2862 * This function changes the 'effective' priority of a task. It does
2863 * not touch ->normal_prio like __setscheduler().
2865 * Used by the rt_mutex code to implement priority inheritance
2866 * logic. Call site only calls if the priority of the task changed.
2868 void rt_mutex_setprio(struct task_struct *p, int prio)
2870 int oldprio, on_rq, running, enqueue_flag = 0;
2872 const struct sched_class *prev_class;
2874 BUG_ON(prio > MAX_PRIO);
2876 rq = __task_rq_lock(p);
2879 * Idle task boosting is a nono in general. There is one
2880 * exception, when PREEMPT_RT and NOHZ is active:
2882 * The idle task calls get_next_timer_interrupt() and holds
2883 * the timer wheel base->lock on the CPU and another CPU wants
2884 * to access the timer (probably to cancel it). We can safely
2885 * ignore the boosting request, as the idle CPU runs this code
2886 * with interrupts disabled and will complete the lock
2887 * protected section without being interrupted. So there is no
2888 * real need to boost.
2890 if (unlikely(p == rq->idle)) {
2891 WARN_ON(p != rq->curr);
2892 WARN_ON(p->pi_blocked_on);
2896 trace_sched_pi_setprio(p, prio);
2897 p->pi_top_task = rt_mutex_get_top_task(p);
2899 prev_class = p->sched_class;
2901 running = task_current(rq, p);
2903 dequeue_task(rq, p, 0);
2905 p->sched_class->put_prev_task(rq, p);
2908 * Boosting condition are:
2909 * 1. -rt task is running and holds mutex A
2910 * --> -dl task blocks on mutex A
2912 * 2. -dl task is running and holds mutex A
2913 * --> -dl task blocks on mutex A and could preempt the
2916 if (dl_prio(prio)) {
2917 if (!dl_prio(p->normal_prio) || (p->pi_top_task &&
2918 dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) {
2919 p->dl.dl_boosted = 1;
2920 p->dl.dl_throttled = 0;
2921 enqueue_flag = ENQUEUE_REPLENISH;
2923 p->dl.dl_boosted = 0;
2924 p->sched_class = &dl_sched_class;
2925 } else if (rt_prio(prio)) {
2926 if (dl_prio(oldprio))
2927 p->dl.dl_boosted = 0;
2929 enqueue_flag = ENQUEUE_HEAD;
2930 p->sched_class = &rt_sched_class;
2932 if (dl_prio(oldprio))
2933 p->dl.dl_boosted = 0;
2934 p->sched_class = &fair_sched_class;
2940 p->sched_class->set_curr_task(rq);
2942 enqueue_task(rq, p, enqueue_flag);
2944 check_class_changed(rq, p, prev_class, oldprio);
2946 __task_rq_unlock(rq);
2950 void set_user_nice(struct task_struct *p, long nice)
2952 int old_prio, delta, on_rq;
2953 unsigned long flags;
2956 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
2959 * We have to be careful, if called from sys_setpriority(),
2960 * the task might be in the middle of scheduling on another CPU.
2962 rq = task_rq_lock(p, &flags);
2964 * The RT priorities are set via sched_setscheduler(), but we still
2965 * allow the 'normal' nice value to be set - but as expected
2966 * it wont have any effect on scheduling until the task is
2967 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
2969 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2970 p->static_prio = NICE_TO_PRIO(nice);
2975 dequeue_task(rq, p, 0);
2977 p->static_prio = NICE_TO_PRIO(nice);
2980 p->prio = effective_prio(p);
2981 delta = p->prio - old_prio;
2984 enqueue_task(rq, p, 0);
2986 * If the task increased its priority or is running and
2987 * lowered its priority, then reschedule its CPU:
2989 if (delta < 0 || (delta > 0 && task_running(rq, p)))
2990 resched_task(rq->curr);
2993 task_rq_unlock(rq, p, &flags);
2995 EXPORT_SYMBOL(set_user_nice);
2998 * can_nice - check if a task can reduce its nice value
3002 int can_nice(const struct task_struct *p, const int nice)
3004 /* convert nice value [19,-20] to rlimit style value [1,40] */
3005 int nice_rlim = 20 - nice;
3007 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3008 capable(CAP_SYS_NICE));
3011 #ifdef __ARCH_WANT_SYS_NICE
3014 * sys_nice - change the priority of the current process.
3015 * @increment: priority increment
3017 * sys_setpriority is a more generic, but much slower function that
3018 * does similar things.
3020 SYSCALL_DEFINE1(nice, int, increment)
3025 * Setpriority might change our priority at the same moment.
3026 * We don't have to worry. Conceptually one call occurs first
3027 * and we have a single winner.
3029 if (increment < -40)
3034 nice = task_nice(current) + increment;
3035 if (nice < MIN_NICE)
3037 if (nice > MAX_NICE)
3040 if (increment < 0 && !can_nice(current, nice))
3043 retval = security_task_setnice(current, nice);
3047 set_user_nice(current, nice);
3054 * task_prio - return the priority value of a given task.
3055 * @p: the task in question.
3057 * Return: The priority value as seen by users in /proc.
3058 * RT tasks are offset by -200. Normal tasks are centered
3059 * around 0, value goes from -16 to +15.
3061 int task_prio(const struct task_struct *p)
3063 return p->prio - MAX_RT_PRIO;
3067 * idle_cpu - is a given cpu idle currently?
3068 * @cpu: the processor in question.
3070 * Return: 1 if the CPU is currently idle. 0 otherwise.
3072 int idle_cpu(int cpu)
3074 struct rq *rq = cpu_rq(cpu);
3076 if (rq->curr != rq->idle)
3083 if (!llist_empty(&rq->wake_list))
3091 * idle_task - return the idle task for a given cpu.
3092 * @cpu: the processor in question.
3094 * Return: The idle task for the cpu @cpu.
3096 struct task_struct *idle_task(int cpu)
3098 return cpu_rq(cpu)->idle;
3102 * find_process_by_pid - find a process with a matching PID value.
3103 * @pid: the pid in question.
3105 * The task of @pid, if found. %NULL otherwise.
3107 static struct task_struct *find_process_by_pid(pid_t pid)
3109 return pid ? find_task_by_vpid(pid) : current;
3113 * This function initializes the sched_dl_entity of a newly becoming
3114 * SCHED_DEADLINE task.
3116 * Only the static values are considered here, the actual runtime and the
3117 * absolute deadline will be properly calculated when the task is enqueued
3118 * for the first time with its new policy.
3121 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3123 struct sched_dl_entity *dl_se = &p->dl;
3125 init_dl_task_timer(dl_se);
3126 dl_se->dl_runtime = attr->sched_runtime;
3127 dl_se->dl_deadline = attr->sched_deadline;
3128 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3129 dl_se->flags = attr->sched_flags;
3130 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3131 dl_se->dl_throttled = 0;
3133 dl_se->dl_yielded = 0;
3136 static void __setscheduler_params(struct task_struct *p,
3137 const struct sched_attr *attr)
3139 int policy = attr->sched_policy;
3141 if (policy == -1) /* setparam */
3146 if (dl_policy(policy))
3147 __setparam_dl(p, attr);
3148 else if (fair_policy(policy))
3149 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3152 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3153 * !rt_policy. Always setting this ensures that things like
3154 * getparam()/getattr() don't report silly values for !rt tasks.
3156 p->rt_priority = attr->sched_priority;
3157 p->normal_prio = normal_prio(p);
3161 /* Actually do priority change: must hold pi & rq lock. */
3162 static void __setscheduler(struct rq *rq, struct task_struct *p,
3163 const struct sched_attr *attr)
3165 __setscheduler_params(p, attr);
3168 * If we get here, there was no pi waiters boosting the
3169 * task. It is safe to use the normal prio.
3171 p->prio = normal_prio(p);
3173 if (dl_prio(p->prio))
3174 p->sched_class = &dl_sched_class;
3175 else if (rt_prio(p->prio))
3176 p->sched_class = &rt_sched_class;
3178 p->sched_class = &fair_sched_class;
3182 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3184 struct sched_dl_entity *dl_se = &p->dl;
3186 attr->sched_priority = p->rt_priority;
3187 attr->sched_runtime = dl_se->dl_runtime;
3188 attr->sched_deadline = dl_se->dl_deadline;
3189 attr->sched_period = dl_se->dl_period;
3190 attr->sched_flags = dl_se->flags;
3194 * This function validates the new parameters of a -deadline task.
3195 * We ask for the deadline not being zero, and greater or equal
3196 * than the runtime, as well as the period of being zero or
3197 * greater than deadline. Furthermore, we have to be sure that
3198 * user parameters are above the internal resolution of 1us (we
3199 * check sched_runtime only since it is always the smaller one) and
3200 * below 2^63 ns (we have to check both sched_deadline and
3201 * sched_period, as the latter can be zero).
3204 __checkparam_dl(const struct sched_attr *attr)
3207 if (attr->sched_deadline == 0)
3211 * Since we truncate DL_SCALE bits, make sure we're at least
3214 if (attr->sched_runtime < (1ULL << DL_SCALE))
3218 * Since we use the MSB for wrap-around and sign issues, make
3219 * sure it's not set (mind that period can be equal to zero).
3221 if (attr->sched_deadline & (1ULL << 63) ||
3222 attr->sched_period & (1ULL << 63))
3225 /* runtime <= deadline <= period (if period != 0) */
3226 if ((attr->sched_period != 0 &&
3227 attr->sched_period < attr->sched_deadline) ||
3228 attr->sched_deadline < attr->sched_runtime)
3235 * check the target process has a UID that matches the current process's
3237 static bool check_same_owner(struct task_struct *p)
3239 const struct cred *cred = current_cred(), *pcred;
3243 pcred = __task_cred(p);
3244 match = (uid_eq(cred->euid, pcred->euid) ||
3245 uid_eq(cred->euid, pcred->uid));
3250 static int __sched_setscheduler(struct task_struct *p,
3251 const struct sched_attr *attr,
3254 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3255 MAX_RT_PRIO - 1 - attr->sched_priority;
3256 int retval, oldprio, oldpolicy = -1, on_rq, running;
3257 int policy = attr->sched_policy;
3258 unsigned long flags;
3259 const struct sched_class *prev_class;
3263 /* may grab non-irq protected spin_locks */
3264 BUG_ON(in_interrupt());
3266 /* double check policy once rq lock held */
3268 reset_on_fork = p->sched_reset_on_fork;
3269 policy = oldpolicy = p->policy;
3271 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3273 if (policy != SCHED_DEADLINE &&
3274 policy != SCHED_FIFO && policy != SCHED_RR &&
3275 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3276 policy != SCHED_IDLE)
3280 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3284 * Valid priorities for SCHED_FIFO and SCHED_RR are
3285 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3286 * SCHED_BATCH and SCHED_IDLE is 0.
3288 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3289 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3291 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3292 (rt_policy(policy) != (attr->sched_priority != 0)))
3296 * Allow unprivileged RT tasks to decrease priority:
3298 if (user && !capable(CAP_SYS_NICE)) {
3299 if (fair_policy(policy)) {
3300 if (attr->sched_nice < task_nice(p) &&
3301 !can_nice(p, attr->sched_nice))
3305 if (rt_policy(policy)) {
3306 unsigned long rlim_rtprio =
3307 task_rlimit(p, RLIMIT_RTPRIO);
3309 /* can't set/change the rt policy */
3310 if (policy != p->policy && !rlim_rtprio)
3313 /* can't increase priority */
3314 if (attr->sched_priority > p->rt_priority &&
3315 attr->sched_priority > rlim_rtprio)
3320 * Can't set/change SCHED_DEADLINE policy at all for now
3321 * (safest behavior); in the future we would like to allow
3322 * unprivileged DL tasks to increase their relative deadline
3323 * or reduce their runtime (both ways reducing utilization)
3325 if (dl_policy(policy))
3329 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3330 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3332 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3333 if (!can_nice(p, task_nice(p)))
3337 /* can't change other user's priorities */
3338 if (!check_same_owner(p))
3341 /* Normal users shall not reset the sched_reset_on_fork flag */
3342 if (p->sched_reset_on_fork && !reset_on_fork)
3347 retval = security_task_setscheduler(p);
3353 * make sure no PI-waiters arrive (or leave) while we are
3354 * changing the priority of the task:
3356 * To be able to change p->policy safely, the appropriate
3357 * runqueue lock must be held.
3359 rq = task_rq_lock(p, &flags);
3362 * Changing the policy of the stop threads its a very bad idea
3364 if (p == rq->stop) {
3365 task_rq_unlock(rq, p, &flags);
3370 * If not changing anything there's no need to proceed further,
3371 * but store a possible modification of reset_on_fork.
3373 if (unlikely(policy == p->policy)) {
3374 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3376 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3378 if (dl_policy(policy))
3381 p->sched_reset_on_fork = reset_on_fork;
3382 task_rq_unlock(rq, p, &flags);
3388 #ifdef CONFIG_RT_GROUP_SCHED
3390 * Do not allow realtime tasks into groups that have no runtime
3393 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3394 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3395 !task_group_is_autogroup(task_group(p))) {
3396 task_rq_unlock(rq, p, &flags);
3401 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3402 cpumask_t *span = rq->rd->span;
3405 * Don't allow tasks with an affinity mask smaller than
3406 * the entire root_domain to become SCHED_DEADLINE. We
3407 * will also fail if there's no bandwidth available.
3409 if (!cpumask_subset(span, &p->cpus_allowed) ||
3410 rq->rd->dl_bw.bw == 0) {
3411 task_rq_unlock(rq, p, &flags);
3418 /* recheck policy now with rq lock held */
3419 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3420 policy = oldpolicy = -1;
3421 task_rq_unlock(rq, p, &flags);
3426 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3427 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3430 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3431 task_rq_unlock(rq, p, &flags);
3435 p->sched_reset_on_fork = reset_on_fork;
3439 * Special case for priority boosted tasks.
3441 * If the new priority is lower or equal (user space view)
3442 * than the current (boosted) priority, we just store the new
3443 * normal parameters and do not touch the scheduler class and
3444 * the runqueue. This will be done when the task deboost
3447 if (rt_mutex_check_prio(p, newprio)) {
3448 __setscheduler_params(p, attr);
3449 task_rq_unlock(rq, p, &flags);
3454 running = task_current(rq, p);
3456 dequeue_task(rq, p, 0);
3458 p->sched_class->put_prev_task(rq, p);
3460 prev_class = p->sched_class;
3461 __setscheduler(rq, p, attr);
3464 p->sched_class->set_curr_task(rq);
3467 * We enqueue to tail when the priority of a task is
3468 * increased (user space view).
3470 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
3473 check_class_changed(rq, p, prev_class, oldprio);
3474 task_rq_unlock(rq, p, &flags);
3476 rt_mutex_adjust_pi(p);
3481 static int _sched_setscheduler(struct task_struct *p, int policy,
3482 const struct sched_param *param, bool check)
3484 struct sched_attr attr = {
3485 .sched_policy = policy,
3486 .sched_priority = param->sched_priority,
3487 .sched_nice = PRIO_TO_NICE(p->static_prio),
3491 * Fixup the legacy SCHED_RESET_ON_FORK hack
3493 if (policy & SCHED_RESET_ON_FORK) {
3494 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3495 policy &= ~SCHED_RESET_ON_FORK;
3496 attr.sched_policy = policy;
3499 return __sched_setscheduler(p, &attr, check);
3502 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3503 * @p: the task in question.
3504 * @policy: new policy.
3505 * @param: structure containing the new RT priority.
3507 * Return: 0 on success. An error code otherwise.
3509 * NOTE that the task may be already dead.
3511 int sched_setscheduler(struct task_struct *p, int policy,
3512 const struct sched_param *param)
3514 return _sched_setscheduler(p, policy, param, true);
3516 EXPORT_SYMBOL_GPL(sched_setscheduler);
3518 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
3520 return __sched_setscheduler(p, attr, true);
3522 EXPORT_SYMBOL_GPL(sched_setattr);
3525 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3526 * @p: the task in question.
3527 * @policy: new policy.
3528 * @param: structure containing the new RT priority.
3530 * Just like sched_setscheduler, only don't bother checking if the
3531 * current context has permission. For example, this is needed in
3532 * stop_machine(): we create temporary high priority worker threads,
3533 * but our caller might not have that capability.
3535 * Return: 0 on success. An error code otherwise.
3537 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3538 const struct sched_param *param)
3540 return _sched_setscheduler(p, policy, param, false);
3544 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3546 struct sched_param lparam;
3547 struct task_struct *p;
3550 if (!param || pid < 0)
3552 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3557 p = find_process_by_pid(pid);
3559 retval = sched_setscheduler(p, policy, &lparam);
3566 * Mimics kernel/events/core.c perf_copy_attr().
3568 static int sched_copy_attr(struct sched_attr __user *uattr,
3569 struct sched_attr *attr)
3574 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
3578 * zero the full structure, so that a short copy will be nice.
3580 memset(attr, 0, sizeof(*attr));
3582 ret = get_user(size, &uattr->size);
3586 if (size > PAGE_SIZE) /* silly large */
3589 if (!size) /* abi compat */
3590 size = SCHED_ATTR_SIZE_VER0;
3592 if (size < SCHED_ATTR_SIZE_VER0)
3596 * If we're handed a bigger struct than we know of,
3597 * ensure all the unknown bits are 0 - i.e. new
3598 * user-space does not rely on any kernel feature
3599 * extensions we dont know about yet.
3601 if (size > sizeof(*attr)) {
3602 unsigned char __user *addr;
3603 unsigned char __user *end;
3606 addr = (void __user *)uattr + sizeof(*attr);
3607 end = (void __user *)uattr + size;
3609 for (; addr < end; addr++) {
3610 ret = get_user(val, addr);
3616 size = sizeof(*attr);
3619 ret = copy_from_user(attr, uattr, size);
3624 * XXX: do we want to be lenient like existing syscalls; or do we want
3625 * to be strict and return an error on out-of-bounds values?
3627 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
3633 put_user(sizeof(*attr), &uattr->size);
3639 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3640 * @pid: the pid in question.
3641 * @policy: new policy.
3642 * @param: structure containing the new RT priority.
3644 * Return: 0 on success. An error code otherwise.
3646 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3647 struct sched_param __user *, param)
3649 /* negative values for policy are not valid */
3653 return do_sched_setscheduler(pid, policy, param);
3657 * sys_sched_setparam - set/change the RT priority of a thread
3658 * @pid: the pid in question.
3659 * @param: structure containing the new RT priority.
3661 * Return: 0 on success. An error code otherwise.
3663 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3665 return do_sched_setscheduler(pid, -1, param);
3669 * sys_sched_setattr - same as above, but with extended sched_attr
3670 * @pid: the pid in question.
3671 * @uattr: structure containing the extended parameters.
3672 * @flags: for future extension.
3674 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
3675 unsigned int, flags)
3677 struct sched_attr attr;
3678 struct task_struct *p;
3681 if (!uattr || pid < 0 || flags)
3684 retval = sched_copy_attr(uattr, &attr);
3688 if ((int)attr.sched_policy < 0)
3693 p = find_process_by_pid(pid);
3695 retval = sched_setattr(p, &attr);
3702 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3703 * @pid: the pid in question.
3705 * Return: On success, the policy of the thread. Otherwise, a negative error
3708 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3710 struct task_struct *p;
3718 p = find_process_by_pid(pid);
3720 retval = security_task_getscheduler(p);
3723 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3730 * sys_sched_getparam - get the RT priority of a thread
3731 * @pid: the pid in question.
3732 * @param: structure containing the RT priority.
3734 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3737 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3739 struct sched_param lp = { .sched_priority = 0 };
3740 struct task_struct *p;
3743 if (!param || pid < 0)
3747 p = find_process_by_pid(pid);
3752 retval = security_task_getscheduler(p);
3756 if (task_has_rt_policy(p))
3757 lp.sched_priority = p->rt_priority;
3761 * This one might sleep, we cannot do it with a spinlock held ...
3763 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3772 static int sched_read_attr(struct sched_attr __user *uattr,
3773 struct sched_attr *attr,
3778 if (!access_ok(VERIFY_WRITE, uattr, usize))
3782 * If we're handed a smaller struct than we know of,
3783 * ensure all the unknown bits are 0 - i.e. old
3784 * user-space does not get uncomplete information.
3786 if (usize < sizeof(*attr)) {
3787 unsigned char *addr;
3790 addr = (void *)attr + usize;
3791 end = (void *)attr + sizeof(*attr);
3793 for (; addr < end; addr++) {
3801 ret = copy_to_user(uattr, attr, attr->size);
3814 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3815 * @pid: the pid in question.
3816 * @uattr: structure containing the extended parameters.
3817 * @size: sizeof(attr) for fwd/bwd comp.
3818 * @flags: for future extension.
3820 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
3821 unsigned int, size, unsigned int, flags)
3823 struct sched_attr attr = {
3824 .size = sizeof(struct sched_attr),
3826 struct task_struct *p;
3829 if (!uattr || pid < 0 || size > PAGE_SIZE ||
3830 size < SCHED_ATTR_SIZE_VER0 || flags)
3834 p = find_process_by_pid(pid);
3839 retval = security_task_getscheduler(p);
3843 attr.sched_policy = p->policy;
3844 if (p->sched_reset_on_fork)
3845 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3846 if (task_has_dl_policy(p))
3847 __getparam_dl(p, &attr);
3848 else if (task_has_rt_policy(p))
3849 attr.sched_priority = p->rt_priority;
3851 attr.sched_nice = task_nice(p);
3855 retval = sched_read_attr(uattr, &attr, size);
3863 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3865 cpumask_var_t cpus_allowed, new_mask;
3866 struct task_struct *p;
3871 p = find_process_by_pid(pid);
3877 /* Prevent p going away */
3881 if (p->flags & PF_NO_SETAFFINITY) {
3885 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
3889 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
3891 goto out_free_cpus_allowed;
3894 if (!check_same_owner(p)) {
3896 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
3903 retval = security_task_setscheduler(p);
3908 cpuset_cpus_allowed(p, cpus_allowed);
3909 cpumask_and(new_mask, in_mask, cpus_allowed);
3912 * Since bandwidth control happens on root_domain basis,
3913 * if admission test is enabled, we only admit -deadline
3914 * tasks allowed to run on all the CPUs in the task's
3918 if (task_has_dl_policy(p)) {
3919 const struct cpumask *span = task_rq(p)->rd->span;
3921 if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {
3928 retval = set_cpus_allowed_ptr(p, new_mask);
3931 cpuset_cpus_allowed(p, cpus_allowed);
3932 if (!cpumask_subset(new_mask, cpus_allowed)) {
3934 * We must have raced with a concurrent cpuset
3935 * update. Just reset the cpus_allowed to the
3936 * cpuset's cpus_allowed
3938 cpumask_copy(new_mask, cpus_allowed);
3943 free_cpumask_var(new_mask);
3944 out_free_cpus_allowed:
3945 free_cpumask_var(cpus_allowed);
3951 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
3952 struct cpumask *new_mask)
3954 if (len < cpumask_size())
3955 cpumask_clear(new_mask);
3956 else if (len > cpumask_size())
3957 len = cpumask_size();
3959 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
3963 * sys_sched_setaffinity - set the cpu affinity of a process
3964 * @pid: pid of the process
3965 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3966 * @user_mask_ptr: user-space pointer to the new cpu mask
3968 * Return: 0 on success. An error code otherwise.
3970 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
3971 unsigned long __user *, user_mask_ptr)
3973 cpumask_var_t new_mask;
3976 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
3979 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
3981 retval = sched_setaffinity(pid, new_mask);
3982 free_cpumask_var(new_mask);
3986 long sched_getaffinity(pid_t pid, struct cpumask *mask)
3988 struct task_struct *p;
3989 unsigned long flags;
3995 p = find_process_by_pid(pid);
3999 retval = security_task_getscheduler(p);
4003 raw_spin_lock_irqsave(&p->pi_lock, flags);
4004 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4005 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4014 * sys_sched_getaffinity - get the cpu affinity of a process
4015 * @pid: pid of the process
4016 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4017 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4019 * Return: 0 on success. An error code otherwise.
4021 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4022 unsigned long __user *, user_mask_ptr)
4027 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4029 if (len & (sizeof(unsigned long)-1))
4032 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4035 ret = sched_getaffinity(pid, mask);
4037 size_t retlen = min_t(size_t, len, cpumask_size());
4039 if (copy_to_user(user_mask_ptr, mask, retlen))
4044 free_cpumask_var(mask);
4050 * sys_sched_yield - yield the current processor to other threads.
4052 * This function yields the current CPU to other tasks. If there are no
4053 * other threads running on this CPU then this function will return.
4057 SYSCALL_DEFINE0(sched_yield)
4059 struct rq *rq = this_rq_lock();
4061 schedstat_inc(rq, yld_count);
4062 current->sched_class->yield_task(rq);
4065 * Since we are going to call schedule() anyway, there's
4066 * no need to preempt or enable interrupts:
4068 __release(rq->lock);
4069 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4070 do_raw_spin_unlock(&rq->lock);
4071 sched_preempt_enable_no_resched();
4078 static void __cond_resched(void)
4080 __preempt_count_add(PREEMPT_ACTIVE);
4082 __preempt_count_sub(PREEMPT_ACTIVE);
4085 int __sched _cond_resched(void)
4087 if (should_resched()) {
4093 EXPORT_SYMBOL(_cond_resched);
4096 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4097 * call schedule, and on return reacquire the lock.
4099 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4100 * operations here to prevent schedule() from being called twice (once via
4101 * spin_unlock(), once by hand).
4103 int __cond_resched_lock(spinlock_t *lock)
4105 int resched = should_resched();
4108 lockdep_assert_held(lock);
4110 if (spin_needbreak(lock) || resched) {
4121 EXPORT_SYMBOL(__cond_resched_lock);
4123 int __sched __cond_resched_softirq(void)
4125 BUG_ON(!in_softirq());
4127 if (should_resched()) {
4135 EXPORT_SYMBOL(__cond_resched_softirq);
4138 * yield - yield the current processor to other threads.
4140 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4142 * The scheduler is at all times free to pick the calling task as the most
4143 * eligible task to run, if removing the yield() call from your code breaks
4144 * it, its already broken.
4146 * Typical broken usage is:
4151 * where one assumes that yield() will let 'the other' process run that will
4152 * make event true. If the current task is a SCHED_FIFO task that will never
4153 * happen. Never use yield() as a progress guarantee!!
4155 * If you want to use yield() to wait for something, use wait_event().
4156 * If you want to use yield() to be 'nice' for others, use cond_resched().
4157 * If you still want to use yield(), do not!
4159 void __sched yield(void)
4161 set_current_state(TASK_RUNNING);
4164 EXPORT_SYMBOL(yield);
4167 * yield_to - yield the current processor to another thread in
4168 * your thread group, or accelerate that thread toward the
4169 * processor it's on.
4171 * @preempt: whether task preemption is allowed or not
4173 * It's the caller's job to ensure that the target task struct
4174 * can't go away on us before we can do any checks.
4177 * true (>0) if we indeed boosted the target task.
4178 * false (0) if we failed to boost the target.
4179 * -ESRCH if there's no task to yield to.
4181 bool __sched yield_to(struct task_struct *p, bool preempt)
4183 struct task_struct *curr = current;
4184 struct rq *rq, *p_rq;
4185 unsigned long flags;
4188 local_irq_save(flags);
4194 * If we're the only runnable task on the rq and target rq also
4195 * has only one task, there's absolutely no point in yielding.
4197 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4202 double_rq_lock(rq, p_rq);
4203 if (task_rq(p) != p_rq) {
4204 double_rq_unlock(rq, p_rq);
4208 if (!curr->sched_class->yield_to_task)
4211 if (curr->sched_class != p->sched_class)
4214 if (task_running(p_rq, p) || p->state)
4217 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4219 schedstat_inc(rq, yld_count);
4221 * Make p's CPU reschedule; pick_next_entity takes care of
4224 if (preempt && rq != p_rq)
4225 resched_task(p_rq->curr);
4229 double_rq_unlock(rq, p_rq);
4231 local_irq_restore(flags);
4238 EXPORT_SYMBOL_GPL(yield_to);
4241 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4242 * that process accounting knows that this is a task in IO wait state.
4244 void __sched io_schedule(void)
4246 struct rq *rq = raw_rq();
4248 delayacct_blkio_start();
4249 atomic_inc(&rq->nr_iowait);
4250 blk_flush_plug(current);
4251 current->in_iowait = 1;
4253 current->in_iowait = 0;
4254 atomic_dec(&rq->nr_iowait);
4255 delayacct_blkio_end();
4257 EXPORT_SYMBOL(io_schedule);
4259 long __sched io_schedule_timeout(long timeout)
4261 struct rq *rq = raw_rq();
4264 delayacct_blkio_start();
4265 atomic_inc(&rq->nr_iowait);
4266 blk_flush_plug(current);
4267 current->in_iowait = 1;
4268 ret = schedule_timeout(timeout);
4269 current->in_iowait = 0;
4270 atomic_dec(&rq->nr_iowait);
4271 delayacct_blkio_end();
4276 * sys_sched_get_priority_max - return maximum RT priority.
4277 * @policy: scheduling class.
4279 * Return: On success, this syscall returns the maximum
4280 * rt_priority that can be used by a given scheduling class.
4281 * On failure, a negative error code is returned.
4283 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4290 ret = MAX_USER_RT_PRIO-1;
4292 case SCHED_DEADLINE:
4303 * sys_sched_get_priority_min - return minimum RT priority.
4304 * @policy: scheduling class.
4306 * Return: On success, this syscall returns the minimum
4307 * rt_priority that can be used by a given scheduling class.
4308 * On failure, a negative error code is returned.
4310 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4319 case SCHED_DEADLINE:
4329 * sys_sched_rr_get_interval - return the default timeslice of a process.
4330 * @pid: pid of the process.
4331 * @interval: userspace pointer to the timeslice value.
4333 * this syscall writes the default timeslice value of a given process
4334 * into the user-space timespec buffer. A value of '0' means infinity.
4336 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4339 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4340 struct timespec __user *, interval)
4342 struct task_struct *p;
4343 unsigned int time_slice;
4344 unsigned long flags;
4354 p = find_process_by_pid(pid);
4358 retval = security_task_getscheduler(p);
4362 rq = task_rq_lock(p, &flags);
4364 if (p->sched_class->get_rr_interval)
4365 time_slice = p->sched_class->get_rr_interval(rq, p);
4366 task_rq_unlock(rq, p, &flags);
4369 jiffies_to_timespec(time_slice, &t);
4370 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4378 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4380 void sched_show_task(struct task_struct *p)
4382 unsigned long free = 0;
4386 state = p->state ? __ffs(p->state) + 1 : 0;
4387 printk(KERN_INFO "%-15.15s %c", p->comm,
4388 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4389 #if BITS_PER_LONG == 32
4390 if (state == TASK_RUNNING)
4391 printk(KERN_CONT " running ");
4393 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4395 if (state == TASK_RUNNING)
4396 printk(KERN_CONT " running task ");
4398 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4400 #ifdef CONFIG_DEBUG_STACK_USAGE
4401 free = stack_not_used(p);
4404 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4406 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4407 task_pid_nr(p), ppid,
4408 (unsigned long)task_thread_info(p)->flags);
4410 print_worker_info(KERN_INFO, p);
4411 show_stack(p, NULL);
4414 void show_state_filter(unsigned long state_filter)
4416 struct task_struct *g, *p;
4418 #if BITS_PER_LONG == 32
4420 " task PC stack pid father\n");
4423 " task PC stack pid father\n");
4426 do_each_thread(g, p) {
4428 * reset the NMI-timeout, listing all files on a slow
4429 * console might take a lot of time:
4431 touch_nmi_watchdog();
4432 if (!state_filter || (p->state & state_filter))
4434 } while_each_thread(g, p);
4436 touch_all_softlockup_watchdogs();
4438 #ifdef CONFIG_SCHED_DEBUG
4439 sysrq_sched_debug_show();
4443 * Only show locks if all tasks are dumped:
4446 debug_show_all_locks();
4449 void init_idle_bootup_task(struct task_struct *idle)
4451 idle->sched_class = &idle_sched_class;
4455 * init_idle - set up an idle thread for a given CPU
4456 * @idle: task in question
4457 * @cpu: cpu the idle task belongs to
4459 * NOTE: this function does not set the idle thread's NEED_RESCHED
4460 * flag, to make booting more robust.
4462 void init_idle(struct task_struct *idle, int cpu)
4464 struct rq *rq = cpu_rq(cpu);
4465 unsigned long flags;
4467 raw_spin_lock_irqsave(&rq->lock, flags);
4469 __sched_fork(0, idle);
4470 idle->state = TASK_RUNNING;
4471 idle->se.exec_start = sched_clock();
4473 do_set_cpus_allowed(idle, cpumask_of(cpu));
4475 * We're having a chicken and egg problem, even though we are
4476 * holding rq->lock, the cpu isn't yet set to this cpu so the
4477 * lockdep check in task_group() will fail.
4479 * Similar case to sched_fork(). / Alternatively we could
4480 * use task_rq_lock() here and obtain the other rq->lock.
4485 __set_task_cpu(idle, cpu);
4488 rq->curr = rq->idle = idle;
4490 #if defined(CONFIG_SMP)
4493 raw_spin_unlock_irqrestore(&rq->lock, flags);
4495 /* Set the preempt count _outside_ the spinlocks! */
4496 init_idle_preempt_count(idle, cpu);
4499 * The idle tasks have their own, simple scheduling class:
4501 idle->sched_class = &idle_sched_class;
4502 ftrace_graph_init_idle_task(idle, cpu);
4503 vtime_init_idle(idle, cpu);
4504 #if defined(CONFIG_SMP)
4505 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4510 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4512 if (p->sched_class && p->sched_class->set_cpus_allowed)
4513 p->sched_class->set_cpus_allowed(p, new_mask);
4515 cpumask_copy(&p->cpus_allowed, new_mask);
4516 p->nr_cpus_allowed = cpumask_weight(new_mask);
4520 * This is how migration works:
4522 * 1) we invoke migration_cpu_stop() on the target CPU using
4524 * 2) stopper starts to run (implicitly forcing the migrated thread
4526 * 3) it checks whether the migrated task is still in the wrong runqueue.
4527 * 4) if it's in the wrong runqueue then the migration thread removes
4528 * it and puts it into the right queue.
4529 * 5) stopper completes and stop_one_cpu() returns and the migration
4534 * Change a given task's CPU affinity. Migrate the thread to a
4535 * proper CPU and schedule it away if the CPU it's executing on
4536 * is removed from the allowed bitmask.
4538 * NOTE: the caller must have a valid reference to the task, the
4539 * task must not exit() & deallocate itself prematurely. The
4540 * call is not atomic; no spinlocks may be held.
4542 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4544 unsigned long flags;
4546 unsigned int dest_cpu;
4549 rq = task_rq_lock(p, &flags);
4551 if (cpumask_equal(&p->cpus_allowed, new_mask))
4554 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4559 do_set_cpus_allowed(p, new_mask);
4561 /* Can the task run on the task's current CPU? If so, we're done */
4562 if (cpumask_test_cpu(task_cpu(p), new_mask))
4565 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4567 struct migration_arg arg = { p, dest_cpu };
4568 /* Need help from migration thread: drop lock and wait. */
4569 task_rq_unlock(rq, p, &flags);
4570 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4571 tlb_migrate_finish(p->mm);
4575 task_rq_unlock(rq, p, &flags);
4579 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4582 * Move (not current) task off this cpu, onto dest cpu. We're doing
4583 * this because either it can't run here any more (set_cpus_allowed()
4584 * away from this CPU, or CPU going down), or because we're
4585 * attempting to rebalance this task on exec (sched_exec).
4587 * So we race with normal scheduler movements, but that's OK, as long
4588 * as the task is no longer on this CPU.
4590 * Returns non-zero if task was successfully migrated.
4592 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4594 struct rq *rq_dest, *rq_src;
4597 if (unlikely(!cpu_active(dest_cpu)))
4600 rq_src = cpu_rq(src_cpu);
4601 rq_dest = cpu_rq(dest_cpu);
4603 raw_spin_lock(&p->pi_lock);
4604 double_rq_lock(rq_src, rq_dest);
4605 /* Already moved. */
4606 if (task_cpu(p) != src_cpu)
4608 /* Affinity changed (again). */
4609 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4613 * If we're not on a rq, the next wake-up will ensure we're
4617 dequeue_task(rq_src, p, 0);
4618 set_task_cpu(p, dest_cpu);
4619 enqueue_task(rq_dest, p, 0);
4620 check_preempt_curr(rq_dest, p, 0);
4625 double_rq_unlock(rq_src, rq_dest);
4626 raw_spin_unlock(&p->pi_lock);
4630 #ifdef CONFIG_NUMA_BALANCING
4631 /* Migrate current task p to target_cpu */
4632 int migrate_task_to(struct task_struct *p, int target_cpu)
4634 struct migration_arg arg = { p, target_cpu };
4635 int curr_cpu = task_cpu(p);
4637 if (curr_cpu == target_cpu)
4640 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4643 /* TODO: This is not properly updating schedstats */
4645 trace_sched_move_numa(p, curr_cpu, target_cpu);
4646 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4650 * Requeue a task on a given node and accurately track the number of NUMA
4651 * tasks on the runqueues
4653 void sched_setnuma(struct task_struct *p, int nid)
4656 unsigned long flags;
4657 bool on_rq, running;
4659 rq = task_rq_lock(p, &flags);
4661 running = task_current(rq, p);
4664 dequeue_task(rq, p, 0);
4666 p->sched_class->put_prev_task(rq, p);
4668 p->numa_preferred_nid = nid;
4671 p->sched_class->set_curr_task(rq);
4673 enqueue_task(rq, p, 0);
4674 task_rq_unlock(rq, p, &flags);
4679 * migration_cpu_stop - this will be executed by a highprio stopper thread
4680 * and performs thread migration by bumping thread off CPU then
4681 * 'pushing' onto another runqueue.
4683 static int migration_cpu_stop(void *data)
4685 struct migration_arg *arg = data;
4688 * The original target cpu might have gone down and we might
4689 * be on another cpu but it doesn't matter.
4691 local_irq_disable();
4692 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4697 #ifdef CONFIG_HOTPLUG_CPU
4700 * Ensures that the idle task is using init_mm right before its cpu goes
4703 void idle_task_exit(void)
4705 struct mm_struct *mm = current->active_mm;
4707 BUG_ON(cpu_online(smp_processor_id()));
4709 if (mm != &init_mm) {
4710 switch_mm(mm, &init_mm, current);
4711 finish_arch_post_lock_switch();
4717 * Since this CPU is going 'away' for a while, fold any nr_active delta
4718 * we might have. Assumes we're called after migrate_tasks() so that the
4719 * nr_active count is stable.
4721 * Also see the comment "Global load-average calculations".
4723 static void calc_load_migrate(struct rq *rq)
4725 long delta = calc_load_fold_active(rq);
4727 atomic_long_add(delta, &calc_load_tasks);
4730 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
4734 static const struct sched_class fake_sched_class = {
4735 .put_prev_task = put_prev_task_fake,
4738 static struct task_struct fake_task = {
4740 * Avoid pull_{rt,dl}_task()
4742 .prio = MAX_PRIO + 1,
4743 .sched_class = &fake_sched_class,
4747 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4748 * try_to_wake_up()->select_task_rq().
4750 * Called with rq->lock held even though we'er in stop_machine() and
4751 * there's no concurrency possible, we hold the required locks anyway
4752 * because of lock validation efforts.
4754 static void migrate_tasks(unsigned int dead_cpu)
4756 struct rq *rq = cpu_rq(dead_cpu);
4757 struct task_struct *next, *stop = rq->stop;
4761 * Fudge the rq selection such that the below task selection loop
4762 * doesn't get stuck on the currently eligible stop task.
4764 * We're currently inside stop_machine() and the rq is either stuck
4765 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4766 * either way we should never end up calling schedule() until we're
4772 * put_prev_task() and pick_next_task() sched
4773 * class method both need to have an up-to-date
4774 * value of rq->clock[_task]
4776 update_rq_clock(rq);
4780 * There's this thread running, bail when that's the only
4783 if (rq->nr_running == 1)
4786 next = pick_next_task(rq, &fake_task);
4788 next->sched_class->put_prev_task(rq, next);
4790 /* Find suitable destination for @next, with force if needed. */
4791 dest_cpu = select_fallback_rq(dead_cpu, next);
4792 raw_spin_unlock(&rq->lock);
4794 __migrate_task(next, dead_cpu, dest_cpu);
4796 raw_spin_lock(&rq->lock);
4802 #endif /* CONFIG_HOTPLUG_CPU */
4804 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4806 static struct ctl_table sd_ctl_dir[] = {
4808 .procname = "sched_domain",
4814 static struct ctl_table sd_ctl_root[] = {
4816 .procname = "kernel",
4818 .child = sd_ctl_dir,
4823 static struct ctl_table *sd_alloc_ctl_entry(int n)
4825 struct ctl_table *entry =
4826 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4831 static void sd_free_ctl_entry(struct ctl_table **tablep)
4833 struct ctl_table *entry;
4836 * In the intermediate directories, both the child directory and
4837 * procname are dynamically allocated and could fail but the mode
4838 * will always be set. In the lowest directory the names are
4839 * static strings and all have proc handlers.
4841 for (entry = *tablep; entry->mode; entry++) {
4843 sd_free_ctl_entry(&entry->child);
4844 if (entry->proc_handler == NULL)
4845 kfree(entry->procname);
4852 static int min_load_idx = 0;
4853 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
4856 set_table_entry(struct ctl_table *entry,
4857 const char *procname, void *data, int maxlen,
4858 umode_t mode, proc_handler *proc_handler,
4861 entry->procname = procname;
4863 entry->maxlen = maxlen;
4865 entry->proc_handler = proc_handler;
4868 entry->extra1 = &min_load_idx;
4869 entry->extra2 = &max_load_idx;
4873 static struct ctl_table *
4874 sd_alloc_ctl_domain_table(struct sched_domain *sd)
4876 struct ctl_table *table = sd_alloc_ctl_entry(14);
4881 set_table_entry(&table[0], "min_interval", &sd->min_interval,
4882 sizeof(long), 0644, proc_doulongvec_minmax, false);
4883 set_table_entry(&table[1], "max_interval", &sd->max_interval,
4884 sizeof(long), 0644, proc_doulongvec_minmax, false);
4885 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4886 sizeof(int), 0644, proc_dointvec_minmax, true);
4887 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4888 sizeof(int), 0644, proc_dointvec_minmax, true);
4889 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4890 sizeof(int), 0644, proc_dointvec_minmax, true);
4891 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4892 sizeof(int), 0644, proc_dointvec_minmax, true);
4893 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4894 sizeof(int), 0644, proc_dointvec_minmax, true);
4895 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4896 sizeof(int), 0644, proc_dointvec_minmax, false);
4897 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4898 sizeof(int), 0644, proc_dointvec_minmax, false);
4899 set_table_entry(&table[9], "cache_nice_tries",
4900 &sd->cache_nice_tries,
4901 sizeof(int), 0644, proc_dointvec_minmax, false);
4902 set_table_entry(&table[10], "flags", &sd->flags,
4903 sizeof(int), 0644, proc_dointvec_minmax, false);
4904 set_table_entry(&table[11], "max_newidle_lb_cost",
4905 &sd->max_newidle_lb_cost,
4906 sizeof(long), 0644, proc_doulongvec_minmax, false);
4907 set_table_entry(&table[12], "name", sd->name,
4908 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
4909 /* &table[13] is terminator */
4914 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
4916 struct ctl_table *entry, *table;
4917 struct sched_domain *sd;
4918 int domain_num = 0, i;
4921 for_each_domain(cpu, sd)
4923 entry = table = sd_alloc_ctl_entry(domain_num + 1);
4928 for_each_domain(cpu, sd) {
4929 snprintf(buf, 32, "domain%d", i);
4930 entry->procname = kstrdup(buf, GFP_KERNEL);
4932 entry->child = sd_alloc_ctl_domain_table(sd);
4939 static struct ctl_table_header *sd_sysctl_header;
4940 static void register_sched_domain_sysctl(void)
4942 int i, cpu_num = num_possible_cpus();
4943 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
4946 WARN_ON(sd_ctl_dir[0].child);
4947 sd_ctl_dir[0].child = entry;
4952 for_each_possible_cpu(i) {
4953 snprintf(buf, 32, "cpu%d", i);
4954 entry->procname = kstrdup(buf, GFP_KERNEL);
4956 entry->child = sd_alloc_ctl_cpu_table(i);
4960 WARN_ON(sd_sysctl_header);
4961 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
4964 /* may be called multiple times per register */
4965 static void unregister_sched_domain_sysctl(void)
4967 if (sd_sysctl_header)
4968 unregister_sysctl_table(sd_sysctl_header);
4969 sd_sysctl_header = NULL;
4970 if (sd_ctl_dir[0].child)
4971 sd_free_ctl_entry(&sd_ctl_dir[0].child);
4974 static void register_sched_domain_sysctl(void)
4977 static void unregister_sched_domain_sysctl(void)
4982 static void set_rq_online(struct rq *rq)
4985 const struct sched_class *class;
4987 cpumask_set_cpu(rq->cpu, rq->rd->online);
4990 for_each_class(class) {
4991 if (class->rq_online)
4992 class->rq_online(rq);
4997 static void set_rq_offline(struct rq *rq)
5000 const struct sched_class *class;
5002 for_each_class(class) {
5003 if (class->rq_offline)
5004 class->rq_offline(rq);
5007 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5013 * migration_call - callback that gets triggered when a CPU is added.
5014 * Here we can start up the necessary migration thread for the new CPU.
5017 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5019 int cpu = (long)hcpu;
5020 unsigned long flags;
5021 struct rq *rq = cpu_rq(cpu);
5023 switch (action & ~CPU_TASKS_FROZEN) {
5025 case CPU_UP_PREPARE:
5026 rq->calc_load_update = calc_load_update;
5030 /* Update our root-domain */
5031 raw_spin_lock_irqsave(&rq->lock, flags);
5033 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5037 raw_spin_unlock_irqrestore(&rq->lock, flags);
5040 #ifdef CONFIG_HOTPLUG_CPU
5042 sched_ttwu_pending();
5043 /* Update our root-domain */
5044 raw_spin_lock_irqsave(&rq->lock, flags);
5046 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5050 BUG_ON(rq->nr_running != 1); /* the migration thread */
5051 raw_spin_unlock_irqrestore(&rq->lock, flags);
5055 calc_load_migrate(rq);
5060 update_max_interval();
5066 * Register at high priority so that task migration (migrate_all_tasks)
5067 * happens before everything else. This has to be lower priority than
5068 * the notifier in the perf_event subsystem, though.
5070 static struct notifier_block migration_notifier = {
5071 .notifier_call = migration_call,
5072 .priority = CPU_PRI_MIGRATION,
5075 static int sched_cpu_active(struct notifier_block *nfb,
5076 unsigned long action, void *hcpu)
5078 switch (action & ~CPU_TASKS_FROZEN) {
5079 case CPU_DOWN_FAILED:
5080 set_cpu_active((long)hcpu, true);
5087 static int sched_cpu_inactive(struct notifier_block *nfb,
5088 unsigned long action, void *hcpu)
5090 unsigned long flags;
5091 long cpu = (long)hcpu;
5093 switch (action & ~CPU_TASKS_FROZEN) {
5094 case CPU_DOWN_PREPARE:
5095 set_cpu_active(cpu, false);
5097 /* explicitly allow suspend */
5098 if (!(action & CPU_TASKS_FROZEN)) {
5099 struct dl_bw *dl_b = dl_bw_of(cpu);
5103 raw_spin_lock_irqsave(&dl_b->lock, flags);
5104 cpus = dl_bw_cpus(cpu);
5105 overflow = __dl_overflow(dl_b, cpus, 0, 0);
5106 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5109 return notifier_from_errno(-EBUSY);
5117 static int __init migration_init(void)
5119 void *cpu = (void *)(long)smp_processor_id();
5122 /* Initialize migration for the boot CPU */
5123 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5124 BUG_ON(err == NOTIFY_BAD);
5125 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5126 register_cpu_notifier(&migration_notifier);
5128 /* Register cpu active notifiers */
5129 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5130 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5134 early_initcall(migration_init);
5139 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5141 #ifdef CONFIG_SCHED_DEBUG
5143 static __read_mostly int sched_debug_enabled;
5145 static int __init sched_debug_setup(char *str)
5147 sched_debug_enabled = 1;
5151 early_param("sched_debug", sched_debug_setup);
5153 static inline bool sched_debug(void)
5155 return sched_debug_enabled;
5158 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5159 struct cpumask *groupmask)
5161 struct sched_group *group = sd->groups;
5164 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5165 cpumask_clear(groupmask);
5167 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5169 if (!(sd->flags & SD_LOAD_BALANCE)) {
5170 printk("does not load-balance\n");
5172 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5177 printk(KERN_CONT "span %s level %s\n", str, sd->name);
5179 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5180 printk(KERN_ERR "ERROR: domain->span does not contain "
5183 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5184 printk(KERN_ERR "ERROR: domain->groups does not contain"
5188 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5192 printk(KERN_ERR "ERROR: group is NULL\n");
5197 * Even though we initialize ->power to something semi-sane,
5198 * we leave power_orig unset. This allows us to detect if
5199 * domain iteration is still funny without causing /0 traps.
5201 if (!group->sgp->power_orig) {
5202 printk(KERN_CONT "\n");
5203 printk(KERN_ERR "ERROR: domain->cpu_power not "
5208 if (!cpumask_weight(sched_group_cpus(group))) {
5209 printk(KERN_CONT "\n");
5210 printk(KERN_ERR "ERROR: empty group\n");
5214 if (!(sd->flags & SD_OVERLAP) &&
5215 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5216 printk(KERN_CONT "\n");
5217 printk(KERN_ERR "ERROR: repeated CPUs\n");
5221 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5223 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5225 printk(KERN_CONT " %s", str);
5226 if (group->sgp->power != SCHED_POWER_SCALE) {
5227 printk(KERN_CONT " (cpu_power = %d)",
5231 group = group->next;
5232 } while (group != sd->groups);
5233 printk(KERN_CONT "\n");
5235 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5236 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5239 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5240 printk(KERN_ERR "ERROR: parent span is not a superset "
5241 "of domain->span\n");
5245 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5249 if (!sched_debug_enabled)
5253 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5257 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5260 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5268 #else /* !CONFIG_SCHED_DEBUG */
5269 # define sched_domain_debug(sd, cpu) do { } while (0)
5270 static inline bool sched_debug(void)
5274 #endif /* CONFIG_SCHED_DEBUG */
5276 static int sd_degenerate(struct sched_domain *sd)
5278 if (cpumask_weight(sched_domain_span(sd)) == 1)
5281 /* Following flags need at least 2 groups */
5282 if (sd->flags & (SD_LOAD_BALANCE |
5283 SD_BALANCE_NEWIDLE |
5287 SD_SHARE_PKG_RESOURCES)) {
5288 if (sd->groups != sd->groups->next)
5292 /* Following flags don't use groups */
5293 if (sd->flags & (SD_WAKE_AFFINE))
5300 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5302 unsigned long cflags = sd->flags, pflags = parent->flags;
5304 if (sd_degenerate(parent))
5307 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5310 /* Flags needing groups don't count if only 1 group in parent */
5311 if (parent->groups == parent->groups->next) {
5312 pflags &= ~(SD_LOAD_BALANCE |
5313 SD_BALANCE_NEWIDLE |
5317 SD_SHARE_PKG_RESOURCES |
5319 if (nr_node_ids == 1)
5320 pflags &= ~SD_SERIALIZE;
5322 if (~cflags & pflags)
5328 static void free_rootdomain(struct rcu_head *rcu)
5330 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5332 cpupri_cleanup(&rd->cpupri);
5333 cpudl_cleanup(&rd->cpudl);
5334 free_cpumask_var(rd->dlo_mask);
5335 free_cpumask_var(rd->rto_mask);
5336 free_cpumask_var(rd->online);
5337 free_cpumask_var(rd->span);
5341 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5343 struct root_domain *old_rd = NULL;
5344 unsigned long flags;
5346 raw_spin_lock_irqsave(&rq->lock, flags);
5351 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5354 cpumask_clear_cpu(rq->cpu, old_rd->span);
5357 * If we dont want to free the old_rd yet then
5358 * set old_rd to NULL to skip the freeing later
5361 if (!atomic_dec_and_test(&old_rd->refcount))
5365 atomic_inc(&rd->refcount);
5368 cpumask_set_cpu(rq->cpu, rd->span);
5369 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5372 raw_spin_unlock_irqrestore(&rq->lock, flags);
5375 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5378 static int init_rootdomain(struct root_domain *rd)
5380 memset(rd, 0, sizeof(*rd));
5382 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5384 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5386 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5388 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5391 init_dl_bw(&rd->dl_bw);
5392 if (cpudl_init(&rd->cpudl) != 0)
5395 if (cpupri_init(&rd->cpupri) != 0)
5400 free_cpumask_var(rd->rto_mask);
5402 free_cpumask_var(rd->dlo_mask);
5404 free_cpumask_var(rd->online);
5406 free_cpumask_var(rd->span);
5412 * By default the system creates a single root-domain with all cpus as
5413 * members (mimicking the global state we have today).
5415 struct root_domain def_root_domain;
5417 static void init_defrootdomain(void)
5419 init_rootdomain(&def_root_domain);
5421 atomic_set(&def_root_domain.refcount, 1);
5424 static struct root_domain *alloc_rootdomain(void)
5426 struct root_domain *rd;
5428 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5432 if (init_rootdomain(rd) != 0) {
5440 static void free_sched_groups(struct sched_group *sg, int free_sgp)
5442 struct sched_group *tmp, *first;
5451 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
5456 } while (sg != first);
5459 static void free_sched_domain(struct rcu_head *rcu)
5461 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5464 * If its an overlapping domain it has private groups, iterate and
5467 if (sd->flags & SD_OVERLAP) {
5468 free_sched_groups(sd->groups, 1);
5469 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5470 kfree(sd->groups->sgp);
5476 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5478 call_rcu(&sd->rcu, free_sched_domain);
5481 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5483 for (; sd; sd = sd->parent)
5484 destroy_sched_domain(sd, cpu);
5488 * Keep a special pointer to the highest sched_domain that has
5489 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5490 * allows us to avoid some pointer chasing select_idle_sibling().
5492 * Also keep a unique ID per domain (we use the first cpu number in
5493 * the cpumask of the domain), this allows us to quickly tell if
5494 * two cpus are in the same cache domain, see cpus_share_cache().
5496 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5497 DEFINE_PER_CPU(int, sd_llc_size);
5498 DEFINE_PER_CPU(int, sd_llc_id);
5499 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5500 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5501 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5503 static void update_top_cache_domain(int cpu)
5505 struct sched_domain *sd;
5506 struct sched_domain *busy_sd = NULL;
5510 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5512 id = cpumask_first(sched_domain_span(sd));
5513 size = cpumask_weight(sched_domain_span(sd));
5514 busy_sd = sd->parent; /* sd_busy */
5516 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5518 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5519 per_cpu(sd_llc_size, cpu) = size;
5520 per_cpu(sd_llc_id, cpu) = id;
5522 sd = lowest_flag_domain(cpu, SD_NUMA);
5523 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5525 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5526 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5530 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5531 * hold the hotplug lock.
5534 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5536 struct rq *rq = cpu_rq(cpu);
5537 struct sched_domain *tmp;
5539 /* Remove the sched domains which do not contribute to scheduling. */
5540 for (tmp = sd; tmp; ) {
5541 struct sched_domain *parent = tmp->parent;
5545 if (sd_parent_degenerate(tmp, parent)) {
5546 tmp->parent = parent->parent;
5548 parent->parent->child = tmp;
5550 * Transfer SD_PREFER_SIBLING down in case of a
5551 * degenerate parent; the spans match for this
5552 * so the property transfers.
5554 if (parent->flags & SD_PREFER_SIBLING)
5555 tmp->flags |= SD_PREFER_SIBLING;
5556 destroy_sched_domain(parent, cpu);
5561 if (sd && sd_degenerate(sd)) {
5564 destroy_sched_domain(tmp, cpu);
5569 sched_domain_debug(sd, cpu);
5571 rq_attach_root(rq, rd);
5573 rcu_assign_pointer(rq->sd, sd);
5574 destroy_sched_domains(tmp, cpu);
5576 update_top_cache_domain(cpu);
5579 /* cpus with isolated domains */
5580 static cpumask_var_t cpu_isolated_map;
5582 /* Setup the mask of cpus configured for isolated domains */
5583 static int __init isolated_cpu_setup(char *str)
5585 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5586 cpulist_parse(str, cpu_isolated_map);
5590 __setup("isolcpus=", isolated_cpu_setup);
5592 static const struct cpumask *cpu_cpu_mask(int cpu)
5594 return cpumask_of_node(cpu_to_node(cpu));
5598 struct sched_domain **__percpu sd;
5599 struct sched_group **__percpu sg;
5600 struct sched_group_power **__percpu sgp;
5604 struct sched_domain ** __percpu sd;
5605 struct root_domain *rd;
5615 struct sched_domain_topology_level;
5617 typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
5618 typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
5620 #define SDTL_OVERLAP 0x01
5622 struct sched_domain_topology_level {
5623 sched_domain_init_f init;
5624 sched_domain_mask_f mask;
5627 struct sd_data data;
5631 * Build an iteration mask that can exclude certain CPUs from the upwards
5634 * Asymmetric node setups can result in situations where the domain tree is of
5635 * unequal depth, make sure to skip domains that already cover the entire
5638 * In that case build_sched_domains() will have terminated the iteration early
5639 * and our sibling sd spans will be empty. Domains should always include the
5640 * cpu they're built on, so check that.
5643 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5645 const struct cpumask *span = sched_domain_span(sd);
5646 struct sd_data *sdd = sd->private;
5647 struct sched_domain *sibling;
5650 for_each_cpu(i, span) {
5651 sibling = *per_cpu_ptr(sdd->sd, i);
5652 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5655 cpumask_set_cpu(i, sched_group_mask(sg));
5660 * Return the canonical balance cpu for this group, this is the first cpu
5661 * of this group that's also in the iteration mask.
5663 int group_balance_cpu(struct sched_group *sg)
5665 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5669 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5671 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5672 const struct cpumask *span = sched_domain_span(sd);
5673 struct cpumask *covered = sched_domains_tmpmask;
5674 struct sd_data *sdd = sd->private;
5675 struct sched_domain *child;
5678 cpumask_clear(covered);
5680 for_each_cpu(i, span) {
5681 struct cpumask *sg_span;
5683 if (cpumask_test_cpu(i, covered))
5686 child = *per_cpu_ptr(sdd->sd, i);
5688 /* See the comment near build_group_mask(). */
5689 if (!cpumask_test_cpu(i, sched_domain_span(child)))
5692 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5693 GFP_KERNEL, cpu_to_node(cpu));
5698 sg_span = sched_group_cpus(sg);
5700 child = child->child;
5701 cpumask_copy(sg_span, sched_domain_span(child));
5703 cpumask_set_cpu(i, sg_span);
5705 cpumask_or(covered, covered, sg_span);
5707 sg->sgp = *per_cpu_ptr(sdd->sgp, i);
5708 if (atomic_inc_return(&sg->sgp->ref) == 1)
5709 build_group_mask(sd, sg);
5712 * Initialize sgp->power such that even if we mess up the
5713 * domains and no possible iteration will get us here, we won't
5716 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);
5717 sg->sgp->power_orig = sg->sgp->power;
5720 * Make sure the first group of this domain contains the
5721 * canonical balance cpu. Otherwise the sched_domain iteration
5722 * breaks. See update_sg_lb_stats().
5724 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5725 group_balance_cpu(sg) == cpu)
5735 sd->groups = groups;
5740 free_sched_groups(first, 0);
5745 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5747 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5748 struct sched_domain *child = sd->child;
5751 cpu = cpumask_first(sched_domain_span(child));
5754 *sg = *per_cpu_ptr(sdd->sg, cpu);
5755 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
5756 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
5763 * build_sched_groups will build a circular linked list of the groups
5764 * covered by the given span, and will set each group's ->cpumask correctly,
5765 * and ->cpu_power to 0.
5767 * Assumes the sched_domain tree is fully constructed
5770 build_sched_groups(struct sched_domain *sd, int cpu)
5772 struct sched_group *first = NULL, *last = NULL;
5773 struct sd_data *sdd = sd->private;
5774 const struct cpumask *span = sched_domain_span(sd);
5775 struct cpumask *covered;
5778 get_group(cpu, sdd, &sd->groups);
5779 atomic_inc(&sd->groups->ref);
5781 if (cpu != cpumask_first(span))
5784 lockdep_assert_held(&sched_domains_mutex);
5785 covered = sched_domains_tmpmask;
5787 cpumask_clear(covered);
5789 for_each_cpu(i, span) {
5790 struct sched_group *sg;
5793 if (cpumask_test_cpu(i, covered))
5796 group = get_group(i, sdd, &sg);
5797 cpumask_clear(sched_group_cpus(sg));
5799 cpumask_setall(sched_group_mask(sg));
5801 for_each_cpu(j, span) {
5802 if (get_group(j, sdd, NULL) != group)
5805 cpumask_set_cpu(j, covered);
5806 cpumask_set_cpu(j, sched_group_cpus(sg));
5821 * Initialize sched groups cpu_power.
5823 * cpu_power indicates the capacity of sched group, which is used while
5824 * distributing the load between different sched groups in a sched domain.
5825 * Typically cpu_power for all the groups in a sched domain will be same unless
5826 * there are asymmetries in the topology. If there are asymmetries, group
5827 * having more cpu_power will pickup more load compared to the group having
5830 static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5832 struct sched_group *sg = sd->groups;
5837 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5839 } while (sg != sd->groups);
5841 if (cpu != group_balance_cpu(sg))
5844 update_group_power(sd, cpu);
5845 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight);
5848 int __weak arch_sd_sibling_asym_packing(void)
5850 return 0*SD_ASYM_PACKING;
5854 * Initializers for schedule domains
5855 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5858 #ifdef CONFIG_SCHED_DEBUG
5859 # define SD_INIT_NAME(sd, type) sd->name = #type
5861 # define SD_INIT_NAME(sd, type) do { } while (0)
5864 #define SD_INIT_FUNC(type) \
5865 static noinline struct sched_domain * \
5866 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5868 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5869 *sd = SD_##type##_INIT; \
5870 SD_INIT_NAME(sd, type); \
5871 sd->private = &tl->data; \
5876 #ifdef CONFIG_SCHED_SMT
5877 SD_INIT_FUNC(SIBLING)
5879 #ifdef CONFIG_SCHED_MC
5882 #ifdef CONFIG_SCHED_BOOK
5886 static int default_relax_domain_level = -1;
5887 int sched_domain_level_max;
5889 static int __init setup_relax_domain_level(char *str)
5891 if (kstrtoint(str, 0, &default_relax_domain_level))
5892 pr_warn("Unable to set relax_domain_level\n");
5896 __setup("relax_domain_level=", setup_relax_domain_level);
5898 static void set_domain_attribute(struct sched_domain *sd,
5899 struct sched_domain_attr *attr)
5903 if (!attr || attr->relax_domain_level < 0) {
5904 if (default_relax_domain_level < 0)
5907 request = default_relax_domain_level;
5909 request = attr->relax_domain_level;
5910 if (request < sd->level) {
5911 /* turn off idle balance on this domain */
5912 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5914 /* turn on idle balance on this domain */
5915 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5919 static void __sdt_free(const struct cpumask *cpu_map);
5920 static int __sdt_alloc(const struct cpumask *cpu_map);
5922 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5923 const struct cpumask *cpu_map)
5927 if (!atomic_read(&d->rd->refcount))
5928 free_rootdomain(&d->rd->rcu); /* fall through */
5930 free_percpu(d->sd); /* fall through */
5932 __sdt_free(cpu_map); /* fall through */
5938 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5939 const struct cpumask *cpu_map)
5941 memset(d, 0, sizeof(*d));
5943 if (__sdt_alloc(cpu_map))
5944 return sa_sd_storage;
5945 d->sd = alloc_percpu(struct sched_domain *);
5947 return sa_sd_storage;
5948 d->rd = alloc_rootdomain();
5951 return sa_rootdomain;
5955 * NULL the sd_data elements we've used to build the sched_domain and
5956 * sched_group structure so that the subsequent __free_domain_allocs()
5957 * will not free the data we're using.
5959 static void claim_allocations(int cpu, struct sched_domain *sd)
5961 struct sd_data *sdd = sd->private;
5963 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
5964 *per_cpu_ptr(sdd->sd, cpu) = NULL;
5966 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
5967 *per_cpu_ptr(sdd->sg, cpu) = NULL;
5969 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref))
5970 *per_cpu_ptr(sdd->sgp, cpu) = NULL;
5973 #ifdef CONFIG_SCHED_SMT
5974 static const struct cpumask *cpu_smt_mask(int cpu)
5976 return topology_thread_cpumask(cpu);
5981 * Topology list, bottom-up.
5983 static struct sched_domain_topology_level default_topology[] = {
5984 #ifdef CONFIG_SCHED_SMT
5985 { sd_init_SIBLING, cpu_smt_mask, },
5987 #ifdef CONFIG_SCHED_MC
5988 { sd_init_MC, cpu_coregroup_mask, },
5990 #ifdef CONFIG_SCHED_BOOK
5991 { sd_init_BOOK, cpu_book_mask, },
5993 { sd_init_CPU, cpu_cpu_mask, },
5997 static struct sched_domain_topology_level *sched_domain_topology = default_topology;
5999 #define for_each_sd_topology(tl) \
6000 for (tl = sched_domain_topology; tl->init; tl++)
6004 static int sched_domains_numa_levels;
6005 static int *sched_domains_numa_distance;
6006 static struct cpumask ***sched_domains_numa_masks;
6007 static int sched_domains_curr_level;
6009 static inline int sd_local_flags(int level)
6011 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE)
6014 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE;
6017 static struct sched_domain *
6018 sd_numa_init(struct sched_domain_topology_level *tl, int cpu)
6020 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6021 int level = tl->numa_level;
6022 int sd_weight = cpumask_weight(
6023 sched_domains_numa_masks[level][cpu_to_node(cpu)]);
6025 *sd = (struct sched_domain){
6026 .min_interval = sd_weight,
6027 .max_interval = 2*sd_weight,
6029 .imbalance_pct = 125,
6030 .cache_nice_tries = 2,
6037 .flags = 1*SD_LOAD_BALANCE
6038 | 1*SD_BALANCE_NEWIDLE
6043 | 0*SD_SHARE_CPUPOWER
6044 | 0*SD_SHARE_PKG_RESOURCES
6046 | 0*SD_PREFER_SIBLING
6048 | sd_local_flags(level)
6050 .last_balance = jiffies,
6051 .balance_interval = sd_weight,
6052 .max_newidle_lb_cost = 0,
6053 .next_decay_max_lb_cost = jiffies,
6055 SD_INIT_NAME(sd, NUMA);
6056 sd->private = &tl->data;
6059 * Ugly hack to pass state to sd_numa_mask()...
6061 sched_domains_curr_level = tl->numa_level;
6066 static const struct cpumask *sd_numa_mask(int cpu)
6068 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6071 static void sched_numa_warn(const char *str)
6073 static int done = false;
6081 printk(KERN_WARNING "ERROR: %s\n\n", str);
6083 for (i = 0; i < nr_node_ids; i++) {
6084 printk(KERN_WARNING " ");
6085 for (j = 0; j < nr_node_ids; j++)
6086 printk(KERN_CONT "%02d ", node_distance(i,j));
6087 printk(KERN_CONT "\n");
6089 printk(KERN_WARNING "\n");
6092 static bool find_numa_distance(int distance)
6096 if (distance == node_distance(0, 0))
6099 for (i = 0; i < sched_domains_numa_levels; i++) {
6100 if (sched_domains_numa_distance[i] == distance)
6107 static void sched_init_numa(void)
6109 int next_distance, curr_distance = node_distance(0, 0);
6110 struct sched_domain_topology_level *tl;
6114 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6115 if (!sched_domains_numa_distance)
6119 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6120 * unique distances in the node_distance() table.
6122 * Assumes node_distance(0,j) includes all distances in
6123 * node_distance(i,j) in order to avoid cubic time.
6125 next_distance = curr_distance;
6126 for (i = 0; i < nr_node_ids; i++) {
6127 for (j = 0; j < nr_node_ids; j++) {
6128 for (k = 0; k < nr_node_ids; k++) {
6129 int distance = node_distance(i, k);
6131 if (distance > curr_distance &&
6132 (distance < next_distance ||
6133 next_distance == curr_distance))
6134 next_distance = distance;
6137 * While not a strong assumption it would be nice to know
6138 * about cases where if node A is connected to B, B is not
6139 * equally connected to A.
6141 if (sched_debug() && node_distance(k, i) != distance)
6142 sched_numa_warn("Node-distance not symmetric");
6144 if (sched_debug() && i && !find_numa_distance(distance))
6145 sched_numa_warn("Node-0 not representative");
6147 if (next_distance != curr_distance) {
6148 sched_domains_numa_distance[level++] = next_distance;
6149 sched_domains_numa_levels = level;
6150 curr_distance = next_distance;
6155 * In case of sched_debug() we verify the above assumption.
6161 * 'level' contains the number of unique distances, excluding the
6162 * identity distance node_distance(i,i).
6164 * The sched_domains_numa_distance[] array includes the actual distance
6169 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6170 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6171 * the array will contain less then 'level' members. This could be
6172 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6173 * in other functions.
6175 * We reset it to 'level' at the end of this function.
6177 sched_domains_numa_levels = 0;
6179 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6180 if (!sched_domains_numa_masks)
6184 * Now for each level, construct a mask per node which contains all
6185 * cpus of nodes that are that many hops away from us.
6187 for (i = 0; i < level; i++) {
6188 sched_domains_numa_masks[i] =
6189 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6190 if (!sched_domains_numa_masks[i])
6193 for (j = 0; j < nr_node_ids; j++) {
6194 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6198 sched_domains_numa_masks[i][j] = mask;
6200 for (k = 0; k < nr_node_ids; k++) {
6201 if (node_distance(j, k) > sched_domains_numa_distance[i])
6204 cpumask_or(mask, mask, cpumask_of_node(k));
6209 tl = kzalloc((ARRAY_SIZE(default_topology) + level) *
6210 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6215 * Copy the default topology bits..
6217 for (i = 0; default_topology[i].init; i++)
6218 tl[i] = default_topology[i];
6221 * .. and append 'j' levels of NUMA goodness.
6223 for (j = 0; j < level; i++, j++) {
6224 tl[i] = (struct sched_domain_topology_level){
6225 .init = sd_numa_init,
6226 .mask = sd_numa_mask,
6227 .flags = SDTL_OVERLAP,
6232 sched_domain_topology = tl;
6234 sched_domains_numa_levels = level;
6237 static void sched_domains_numa_masks_set(int cpu)
6240 int node = cpu_to_node(cpu);
6242 for (i = 0; i < sched_domains_numa_levels; i++) {
6243 for (j = 0; j < nr_node_ids; j++) {
6244 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6245 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6250 static void sched_domains_numa_masks_clear(int cpu)
6253 for (i = 0; i < sched_domains_numa_levels; i++) {
6254 for (j = 0; j < nr_node_ids; j++)
6255 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6260 * Update sched_domains_numa_masks[level][node] array when new cpus
6263 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6264 unsigned long action,
6267 int cpu = (long)hcpu;
6269 switch (action & ~CPU_TASKS_FROZEN) {
6271 sched_domains_numa_masks_set(cpu);
6275 sched_domains_numa_masks_clear(cpu);
6285 static inline void sched_init_numa(void)
6289 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6290 unsigned long action,
6295 #endif /* CONFIG_NUMA */
6297 static int __sdt_alloc(const struct cpumask *cpu_map)
6299 struct sched_domain_topology_level *tl;
6302 for_each_sd_topology(tl) {
6303 struct sd_data *sdd = &tl->data;
6305 sdd->sd = alloc_percpu(struct sched_domain *);
6309 sdd->sg = alloc_percpu(struct sched_group *);
6313 sdd->sgp = alloc_percpu(struct sched_group_power *);
6317 for_each_cpu(j, cpu_map) {
6318 struct sched_domain *sd;
6319 struct sched_group *sg;
6320 struct sched_group_power *sgp;
6322 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6323 GFP_KERNEL, cpu_to_node(j));
6327 *per_cpu_ptr(sdd->sd, j) = sd;
6329 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6330 GFP_KERNEL, cpu_to_node(j));
6336 *per_cpu_ptr(sdd->sg, j) = sg;
6338 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(),
6339 GFP_KERNEL, cpu_to_node(j));
6343 *per_cpu_ptr(sdd->sgp, j) = sgp;
6350 static void __sdt_free(const struct cpumask *cpu_map)
6352 struct sched_domain_topology_level *tl;
6355 for_each_sd_topology(tl) {
6356 struct sd_data *sdd = &tl->data;
6358 for_each_cpu(j, cpu_map) {
6359 struct sched_domain *sd;
6362 sd = *per_cpu_ptr(sdd->sd, j);
6363 if (sd && (sd->flags & SD_OVERLAP))
6364 free_sched_groups(sd->groups, 0);
6365 kfree(*per_cpu_ptr(sdd->sd, j));
6369 kfree(*per_cpu_ptr(sdd->sg, j));
6371 kfree(*per_cpu_ptr(sdd->sgp, j));
6373 free_percpu(sdd->sd);
6375 free_percpu(sdd->sg);
6377 free_percpu(sdd->sgp);
6382 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6383 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6384 struct sched_domain *child, int cpu)
6386 struct sched_domain *sd = tl->init(tl, cpu);
6390 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6392 sd->level = child->level + 1;
6393 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6397 set_domain_attribute(sd, attr);
6403 * Build sched domains for a given set of cpus and attach the sched domains
6404 * to the individual cpus
6406 static int build_sched_domains(const struct cpumask *cpu_map,
6407 struct sched_domain_attr *attr)
6409 enum s_alloc alloc_state;
6410 struct sched_domain *sd;
6412 int i, ret = -ENOMEM;
6414 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6415 if (alloc_state != sa_rootdomain)
6418 /* Set up domains for cpus specified by the cpu_map. */
6419 for_each_cpu(i, cpu_map) {
6420 struct sched_domain_topology_level *tl;
6423 for_each_sd_topology(tl) {
6424 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6425 if (tl == sched_domain_topology)
6426 *per_cpu_ptr(d.sd, i) = sd;
6427 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6428 sd->flags |= SD_OVERLAP;
6429 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6434 /* Build the groups for the domains */
6435 for_each_cpu(i, cpu_map) {
6436 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6437 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6438 if (sd->flags & SD_OVERLAP) {
6439 if (build_overlap_sched_groups(sd, i))
6442 if (build_sched_groups(sd, i))
6448 /* Calculate CPU power for physical packages and nodes */
6449 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6450 if (!cpumask_test_cpu(i, cpu_map))
6453 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6454 claim_allocations(i, sd);
6455 init_sched_groups_power(i, sd);
6459 /* Attach the domains */
6461 for_each_cpu(i, cpu_map) {
6462 sd = *per_cpu_ptr(d.sd, i);
6463 cpu_attach_domain(sd, d.rd, i);
6469 __free_domain_allocs(&d, alloc_state, cpu_map);
6473 static cpumask_var_t *doms_cur; /* current sched domains */
6474 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6475 static struct sched_domain_attr *dattr_cur;
6476 /* attribues of custom domains in 'doms_cur' */
6479 * Special case: If a kmalloc of a doms_cur partition (array of
6480 * cpumask) fails, then fallback to a single sched domain,
6481 * as determined by the single cpumask fallback_doms.
6483 static cpumask_var_t fallback_doms;
6486 * arch_update_cpu_topology lets virtualized architectures update the
6487 * cpu core maps. It is supposed to return 1 if the topology changed
6488 * or 0 if it stayed the same.
6490 int __weak arch_update_cpu_topology(void)
6495 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6498 cpumask_var_t *doms;
6500 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6503 for (i = 0; i < ndoms; i++) {
6504 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6505 free_sched_domains(doms, i);
6512 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6515 for (i = 0; i < ndoms; i++)
6516 free_cpumask_var(doms[i]);
6521 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6522 * For now this just excludes isolated cpus, but could be used to
6523 * exclude other special cases in the future.
6525 static int init_sched_domains(const struct cpumask *cpu_map)
6529 arch_update_cpu_topology();
6531 doms_cur = alloc_sched_domains(ndoms_cur);
6533 doms_cur = &fallback_doms;
6534 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6535 err = build_sched_domains(doms_cur[0], NULL);
6536 register_sched_domain_sysctl();
6542 * Detach sched domains from a group of cpus specified in cpu_map
6543 * These cpus will now be attached to the NULL domain
6545 static void detach_destroy_domains(const struct cpumask *cpu_map)
6550 for_each_cpu(i, cpu_map)
6551 cpu_attach_domain(NULL, &def_root_domain, i);
6555 /* handle null as "default" */
6556 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6557 struct sched_domain_attr *new, int idx_new)
6559 struct sched_domain_attr tmp;
6566 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6567 new ? (new + idx_new) : &tmp,
6568 sizeof(struct sched_domain_attr));
6572 * Partition sched domains as specified by the 'ndoms_new'
6573 * cpumasks in the array doms_new[] of cpumasks. This compares
6574 * doms_new[] to the current sched domain partitioning, doms_cur[].
6575 * It destroys each deleted domain and builds each new domain.
6577 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6578 * The masks don't intersect (don't overlap.) We should setup one
6579 * sched domain for each mask. CPUs not in any of the cpumasks will
6580 * not be load balanced. If the same cpumask appears both in the
6581 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6584 * The passed in 'doms_new' should be allocated using
6585 * alloc_sched_domains. This routine takes ownership of it and will
6586 * free_sched_domains it when done with it. If the caller failed the
6587 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6588 * and partition_sched_domains() will fallback to the single partition
6589 * 'fallback_doms', it also forces the domains to be rebuilt.
6591 * If doms_new == NULL it will be replaced with cpu_online_mask.
6592 * ndoms_new == 0 is a special case for destroying existing domains,
6593 * and it will not create the default domain.
6595 * Call with hotplug lock held
6597 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
6598 struct sched_domain_attr *dattr_new)
6603 mutex_lock(&sched_domains_mutex);
6605 /* always unregister in case we don't destroy any domains */
6606 unregister_sched_domain_sysctl();
6608 /* Let architecture update cpu core mappings. */
6609 new_topology = arch_update_cpu_topology();
6611 n = doms_new ? ndoms_new : 0;
6613 /* Destroy deleted domains */
6614 for (i = 0; i < ndoms_cur; i++) {
6615 for (j = 0; j < n && !new_topology; j++) {
6616 if (cpumask_equal(doms_cur[i], doms_new[j])
6617 && dattrs_equal(dattr_cur, i, dattr_new, j))
6620 /* no match - a current sched domain not in new doms_new[] */
6621 detach_destroy_domains(doms_cur[i]);
6627 if (doms_new == NULL) {
6629 doms_new = &fallback_doms;
6630 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6631 WARN_ON_ONCE(dattr_new);
6634 /* Build new domains */
6635 for (i = 0; i < ndoms_new; i++) {
6636 for (j = 0; j < n && !new_topology; j++) {
6637 if (cpumask_equal(doms_new[i], doms_cur[j])
6638 && dattrs_equal(dattr_new, i, dattr_cur, j))
6641 /* no match - add a new doms_new */
6642 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6647 /* Remember the new sched domains */
6648 if (doms_cur != &fallback_doms)
6649 free_sched_domains(doms_cur, ndoms_cur);
6650 kfree(dattr_cur); /* kfree(NULL) is safe */
6651 doms_cur = doms_new;
6652 dattr_cur = dattr_new;
6653 ndoms_cur = ndoms_new;
6655 register_sched_domain_sysctl();
6657 mutex_unlock(&sched_domains_mutex);
6660 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
6663 * Update cpusets according to cpu_active mask. If cpusets are
6664 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6665 * around partition_sched_domains().
6667 * If we come here as part of a suspend/resume, don't touch cpusets because we
6668 * want to restore it back to its original state upon resume anyway.
6670 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6674 case CPU_ONLINE_FROZEN:
6675 case CPU_DOWN_FAILED_FROZEN:
6678 * num_cpus_frozen tracks how many CPUs are involved in suspend
6679 * resume sequence. As long as this is not the last online
6680 * operation in the resume sequence, just build a single sched
6681 * domain, ignoring cpusets.
6684 if (likely(num_cpus_frozen)) {
6685 partition_sched_domains(1, NULL, NULL);
6690 * This is the last CPU online operation. So fall through and
6691 * restore the original sched domains by considering the
6692 * cpuset configurations.
6696 case CPU_DOWN_FAILED:
6697 cpuset_update_active_cpus(true);
6705 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6709 case CPU_DOWN_PREPARE:
6710 cpuset_update_active_cpus(false);
6712 case CPU_DOWN_PREPARE_FROZEN:
6714 partition_sched_domains(1, NULL, NULL);
6722 void __init sched_init_smp(void)
6724 cpumask_var_t non_isolated_cpus;
6726 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6727 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6732 * There's no userspace yet to cause hotplug operations; hence all the
6733 * cpu masks are stable and all blatant races in the below code cannot
6736 mutex_lock(&sched_domains_mutex);
6737 init_sched_domains(cpu_active_mask);
6738 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6739 if (cpumask_empty(non_isolated_cpus))
6740 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6741 mutex_unlock(&sched_domains_mutex);
6743 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6744 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6745 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6749 /* Move init over to a non-isolated CPU */
6750 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6752 sched_init_granularity();
6753 free_cpumask_var(non_isolated_cpus);
6755 init_sched_rt_class();
6756 init_sched_dl_class();
6759 void __init sched_init_smp(void)
6761 sched_init_granularity();
6763 #endif /* CONFIG_SMP */
6765 const_debug unsigned int sysctl_timer_migration = 1;
6767 int in_sched_functions(unsigned long addr)
6769 return in_lock_functions(addr) ||
6770 (addr >= (unsigned long)__sched_text_start
6771 && addr < (unsigned long)__sched_text_end);
6774 #ifdef CONFIG_CGROUP_SCHED
6776 * Default task group.
6777 * Every task in system belongs to this group at bootup.
6779 struct task_group root_task_group;
6780 LIST_HEAD(task_groups);
6783 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6785 void __init sched_init(void)
6788 unsigned long alloc_size = 0, ptr;
6790 #ifdef CONFIG_FAIR_GROUP_SCHED
6791 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6793 #ifdef CONFIG_RT_GROUP_SCHED
6794 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6796 #ifdef CONFIG_CPUMASK_OFFSTACK
6797 alloc_size += num_possible_cpus() * cpumask_size();
6800 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6802 #ifdef CONFIG_FAIR_GROUP_SCHED
6803 root_task_group.se = (struct sched_entity **)ptr;
6804 ptr += nr_cpu_ids * sizeof(void **);
6806 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6807 ptr += nr_cpu_ids * sizeof(void **);
6809 #endif /* CONFIG_FAIR_GROUP_SCHED */
6810 #ifdef CONFIG_RT_GROUP_SCHED
6811 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
6812 ptr += nr_cpu_ids * sizeof(void **);
6814 root_task_group.rt_rq = (struct rt_rq **)ptr;
6815 ptr += nr_cpu_ids * sizeof(void **);
6817 #endif /* CONFIG_RT_GROUP_SCHED */
6818 #ifdef CONFIG_CPUMASK_OFFSTACK
6819 for_each_possible_cpu(i) {
6820 per_cpu(load_balance_mask, i) = (void *)ptr;
6821 ptr += cpumask_size();
6823 #endif /* CONFIG_CPUMASK_OFFSTACK */
6826 init_rt_bandwidth(&def_rt_bandwidth,
6827 global_rt_period(), global_rt_runtime());
6828 init_dl_bandwidth(&def_dl_bandwidth,
6829 global_rt_period(), global_rt_runtime());
6832 init_defrootdomain();
6835 #ifdef CONFIG_RT_GROUP_SCHED
6836 init_rt_bandwidth(&root_task_group.rt_bandwidth,
6837 global_rt_period(), global_rt_runtime());
6838 #endif /* CONFIG_RT_GROUP_SCHED */
6840 #ifdef CONFIG_CGROUP_SCHED
6841 list_add(&root_task_group.list, &task_groups);
6842 INIT_LIST_HEAD(&root_task_group.children);
6843 INIT_LIST_HEAD(&root_task_group.siblings);
6844 autogroup_init(&init_task);
6846 #endif /* CONFIG_CGROUP_SCHED */
6848 for_each_possible_cpu(i) {
6852 raw_spin_lock_init(&rq->lock);
6854 rq->calc_load_active = 0;
6855 rq->calc_load_update = jiffies + LOAD_FREQ;
6856 init_cfs_rq(&rq->cfs);
6857 init_rt_rq(&rq->rt, rq);
6858 init_dl_rq(&rq->dl, rq);
6859 #ifdef CONFIG_FAIR_GROUP_SCHED
6860 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6861 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6863 * How much cpu bandwidth does root_task_group get?
6865 * In case of task-groups formed thr' the cgroup filesystem, it
6866 * gets 100% of the cpu resources in the system. This overall
6867 * system cpu resource is divided among the tasks of
6868 * root_task_group and its child task-groups in a fair manner,
6869 * based on each entity's (task or task-group's) weight
6870 * (se->load.weight).
6872 * In other words, if root_task_group has 10 tasks of weight
6873 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6874 * then A0's share of the cpu resource is:
6876 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6878 * We achieve this by letting root_task_group's tasks sit
6879 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6881 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
6882 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
6883 #endif /* CONFIG_FAIR_GROUP_SCHED */
6885 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
6886 #ifdef CONFIG_RT_GROUP_SCHED
6887 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
6890 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6891 rq->cpu_load[j] = 0;
6893 rq->last_load_update_tick = jiffies;
6898 rq->cpu_power = SCHED_POWER_SCALE;
6899 rq->post_schedule = 0;
6900 rq->active_balance = 0;
6901 rq->next_balance = jiffies;
6906 rq->avg_idle = 2*sysctl_sched_migration_cost;
6907 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
6909 INIT_LIST_HEAD(&rq->cfs_tasks);
6911 rq_attach_root(rq, &def_root_domain);
6912 #ifdef CONFIG_NO_HZ_COMMON
6915 #ifdef CONFIG_NO_HZ_FULL
6916 rq->last_sched_tick = 0;
6920 atomic_set(&rq->nr_iowait, 0);
6923 set_load_weight(&init_task);
6925 #ifdef CONFIG_PREEMPT_NOTIFIERS
6926 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
6930 * The boot idle thread does lazy MMU switching as well:
6932 atomic_inc(&init_mm.mm_count);
6933 enter_lazy_tlb(&init_mm, current);
6936 * Make us the idle thread. Technically, schedule() should not be
6937 * called from this thread, however somewhere below it might be,
6938 * but because we are the idle thread, we just pick up running again
6939 * when this runqueue becomes "idle".
6941 init_idle(current, smp_processor_id());
6943 calc_load_update = jiffies + LOAD_FREQ;
6946 * During early bootup we pretend to be a normal task:
6948 current->sched_class = &fair_sched_class;
6951 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
6952 /* May be allocated at isolcpus cmdline parse time */
6953 if (cpu_isolated_map == NULL)
6954 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
6955 idle_thread_set_boot_cpu();
6957 init_sched_fair_class();
6959 scheduler_running = 1;
6962 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
6963 static inline int preempt_count_equals(int preempt_offset)
6965 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
6967 return (nested == preempt_offset);
6970 void __might_sleep(const char *file, int line, int preempt_offset)
6972 static unsigned long prev_jiffy; /* ratelimiting */
6974 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
6975 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
6976 !is_idle_task(current)) ||
6977 system_state != SYSTEM_RUNNING || oops_in_progress)
6979 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6981 prev_jiffy = jiffies;
6984 "BUG: sleeping function called from invalid context at %s:%d\n",
6987 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
6988 in_atomic(), irqs_disabled(),
6989 current->pid, current->comm);
6991 debug_show_held_locks(current);
6992 if (irqs_disabled())
6993 print_irqtrace_events(current);
6994 #ifdef CONFIG_DEBUG_PREEMPT
6995 if (!preempt_count_equals(preempt_offset)) {
6996 pr_err("Preemption disabled at:");
6997 print_ip_sym(current->preempt_disable_ip);
7003 EXPORT_SYMBOL(__might_sleep);
7006 #ifdef CONFIG_MAGIC_SYSRQ
7007 static void normalize_task(struct rq *rq, struct task_struct *p)
7009 const struct sched_class *prev_class = p->sched_class;
7010 struct sched_attr attr = {
7011 .sched_policy = SCHED_NORMAL,
7013 int old_prio = p->prio;
7018 dequeue_task(rq, p, 0);
7019 __setscheduler(rq, p, &attr);
7021 enqueue_task(rq, p, 0);
7022 resched_task(rq->curr);
7025 check_class_changed(rq, p, prev_class, old_prio);
7028 void normalize_rt_tasks(void)
7030 struct task_struct *g, *p;
7031 unsigned long flags;
7034 read_lock_irqsave(&tasklist_lock, flags);
7035 do_each_thread(g, p) {
7037 * Only normalize user tasks:
7042 p->se.exec_start = 0;
7043 #ifdef CONFIG_SCHEDSTATS
7044 p->se.statistics.wait_start = 0;
7045 p->se.statistics.sleep_start = 0;
7046 p->se.statistics.block_start = 0;
7049 if (!dl_task(p) && !rt_task(p)) {
7051 * Renice negative nice level userspace
7054 if (task_nice(p) < 0 && p->mm)
7055 set_user_nice(p, 0);
7059 raw_spin_lock(&p->pi_lock);
7060 rq = __task_rq_lock(p);
7062 normalize_task(rq, p);
7064 __task_rq_unlock(rq);
7065 raw_spin_unlock(&p->pi_lock);
7066 } while_each_thread(g, p);
7068 read_unlock_irqrestore(&tasklist_lock, flags);
7071 #endif /* CONFIG_MAGIC_SYSRQ */
7073 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7075 * These functions are only useful for the IA64 MCA handling, or kdb.
7077 * They can only be called when the whole system has been
7078 * stopped - every CPU needs to be quiescent, and no scheduling
7079 * activity can take place. Using them for anything else would
7080 * be a serious bug, and as a result, they aren't even visible
7081 * under any other configuration.
7085 * curr_task - return the current task for a given cpu.
7086 * @cpu: the processor in question.
7088 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7090 * Return: The current task for @cpu.
7092 struct task_struct *curr_task(int cpu)
7094 return cpu_curr(cpu);
7097 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7101 * set_curr_task - set the current task for a given cpu.
7102 * @cpu: the processor in question.
7103 * @p: the task pointer to set.
7105 * Description: This function must only be used when non-maskable interrupts
7106 * are serviced on a separate stack. It allows the architecture to switch the
7107 * notion of the current task on a cpu in a non-blocking manner. This function
7108 * must be called with all CPU's synchronized, and interrupts disabled, the
7109 * and caller must save the original value of the current task (see
7110 * curr_task() above) and restore that value before reenabling interrupts and
7111 * re-starting the system.
7113 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7115 void set_curr_task(int cpu, struct task_struct *p)
7122 #ifdef CONFIG_CGROUP_SCHED
7123 /* task_group_lock serializes the addition/removal of task groups */
7124 static DEFINE_SPINLOCK(task_group_lock);
7126 static void free_sched_group(struct task_group *tg)
7128 free_fair_sched_group(tg);
7129 free_rt_sched_group(tg);
7134 /* allocate runqueue etc for a new task group */
7135 struct task_group *sched_create_group(struct task_group *parent)
7137 struct task_group *tg;
7139 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7141 return ERR_PTR(-ENOMEM);
7143 if (!alloc_fair_sched_group(tg, parent))
7146 if (!alloc_rt_sched_group(tg, parent))
7152 free_sched_group(tg);
7153 return ERR_PTR(-ENOMEM);
7156 void sched_online_group(struct task_group *tg, struct task_group *parent)
7158 unsigned long flags;
7160 spin_lock_irqsave(&task_group_lock, flags);
7161 list_add_rcu(&tg->list, &task_groups);
7163 WARN_ON(!parent); /* root should already exist */
7165 tg->parent = parent;
7166 INIT_LIST_HEAD(&tg->children);
7167 list_add_rcu(&tg->siblings, &parent->children);
7168 spin_unlock_irqrestore(&task_group_lock, flags);
7171 /* rcu callback to free various structures associated with a task group */
7172 static void free_sched_group_rcu(struct rcu_head *rhp)
7174 /* now it should be safe to free those cfs_rqs */
7175 free_sched_group(container_of(rhp, struct task_group, rcu));
7178 /* Destroy runqueue etc associated with a task group */
7179 void sched_destroy_group(struct task_group *tg)
7181 /* wait for possible concurrent references to cfs_rqs complete */
7182 call_rcu(&tg->rcu, free_sched_group_rcu);
7185 void sched_offline_group(struct task_group *tg)
7187 unsigned long flags;
7190 /* end participation in shares distribution */
7191 for_each_possible_cpu(i)
7192 unregister_fair_sched_group(tg, i);
7194 spin_lock_irqsave(&task_group_lock, flags);
7195 list_del_rcu(&tg->list);
7196 list_del_rcu(&tg->siblings);
7197 spin_unlock_irqrestore(&task_group_lock, flags);
7200 /* change task's runqueue when it moves between groups.
7201 * The caller of this function should have put the task in its new group
7202 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7203 * reflect its new group.
7205 void sched_move_task(struct task_struct *tsk)
7207 struct task_group *tg;
7209 unsigned long flags;
7212 rq = task_rq_lock(tsk, &flags);
7214 running = task_current(rq, tsk);
7218 dequeue_task(rq, tsk, 0);
7219 if (unlikely(running))
7220 tsk->sched_class->put_prev_task(rq, tsk);
7222 tg = container_of(task_css_check(tsk, cpu_cgrp_id,
7223 lockdep_is_held(&tsk->sighand->siglock)),
7224 struct task_group, css);
7225 tg = autogroup_task_group(tsk, tg);
7226 tsk->sched_task_group = tg;
7228 #ifdef CONFIG_FAIR_GROUP_SCHED
7229 if (tsk->sched_class->task_move_group)
7230 tsk->sched_class->task_move_group(tsk, on_rq);
7233 set_task_rq(tsk, task_cpu(tsk));
7235 if (unlikely(running))
7236 tsk->sched_class->set_curr_task(rq);
7238 enqueue_task(rq, tsk, 0);
7240 task_rq_unlock(rq, tsk, &flags);
7242 #endif /* CONFIG_CGROUP_SCHED */
7244 #ifdef CONFIG_RT_GROUP_SCHED
7246 * Ensure that the real time constraints are schedulable.
7248 static DEFINE_MUTEX(rt_constraints_mutex);
7250 /* Must be called with tasklist_lock held */
7251 static inline int tg_has_rt_tasks(struct task_group *tg)
7253 struct task_struct *g, *p;
7255 do_each_thread(g, p) {
7256 if (rt_task(p) && task_rq(p)->rt.tg == tg)
7258 } while_each_thread(g, p);
7263 struct rt_schedulable_data {
7264 struct task_group *tg;
7269 static int tg_rt_schedulable(struct task_group *tg, void *data)
7271 struct rt_schedulable_data *d = data;
7272 struct task_group *child;
7273 unsigned long total, sum = 0;
7274 u64 period, runtime;
7276 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7277 runtime = tg->rt_bandwidth.rt_runtime;
7280 period = d->rt_period;
7281 runtime = d->rt_runtime;
7285 * Cannot have more runtime than the period.
7287 if (runtime > period && runtime != RUNTIME_INF)
7291 * Ensure we don't starve existing RT tasks.
7293 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7296 total = to_ratio(period, runtime);
7299 * Nobody can have more than the global setting allows.
7301 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7305 * The sum of our children's runtime should not exceed our own.
7307 list_for_each_entry_rcu(child, &tg->children, siblings) {
7308 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7309 runtime = child->rt_bandwidth.rt_runtime;
7311 if (child == d->tg) {
7312 period = d->rt_period;
7313 runtime = d->rt_runtime;
7316 sum += to_ratio(period, runtime);
7325 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7329 struct rt_schedulable_data data = {
7331 .rt_period = period,
7332 .rt_runtime = runtime,
7336 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7342 static int tg_set_rt_bandwidth(struct task_group *tg,
7343 u64 rt_period, u64 rt_runtime)
7347 mutex_lock(&rt_constraints_mutex);
7348 read_lock(&tasklist_lock);
7349 err = __rt_schedulable(tg, rt_period, rt_runtime);
7353 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7354 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7355 tg->rt_bandwidth.rt_runtime = rt_runtime;
7357 for_each_possible_cpu(i) {
7358 struct rt_rq *rt_rq = tg->rt_rq[i];
7360 raw_spin_lock(&rt_rq->rt_runtime_lock);
7361 rt_rq->rt_runtime = rt_runtime;
7362 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7364 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7366 read_unlock(&tasklist_lock);
7367 mutex_unlock(&rt_constraints_mutex);
7372 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7374 u64 rt_runtime, rt_period;
7376 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7377 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7378 if (rt_runtime_us < 0)
7379 rt_runtime = RUNTIME_INF;
7381 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7384 static long sched_group_rt_runtime(struct task_group *tg)
7388 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7391 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7392 do_div(rt_runtime_us, NSEC_PER_USEC);
7393 return rt_runtime_us;
7396 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
7398 u64 rt_runtime, rt_period;
7400 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
7401 rt_runtime = tg->rt_bandwidth.rt_runtime;
7406 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7409 static long sched_group_rt_period(struct task_group *tg)
7413 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7414 do_div(rt_period_us, NSEC_PER_USEC);
7415 return rt_period_us;
7417 #endif /* CONFIG_RT_GROUP_SCHED */
7419 #ifdef CONFIG_RT_GROUP_SCHED
7420 static int sched_rt_global_constraints(void)
7424 mutex_lock(&rt_constraints_mutex);
7425 read_lock(&tasklist_lock);
7426 ret = __rt_schedulable(NULL, 0, 0);
7427 read_unlock(&tasklist_lock);
7428 mutex_unlock(&rt_constraints_mutex);
7433 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7435 /* Don't accept realtime tasks when there is no way for them to run */
7436 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7442 #else /* !CONFIG_RT_GROUP_SCHED */
7443 static int sched_rt_global_constraints(void)
7445 unsigned long flags;
7448 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7449 for_each_possible_cpu(i) {
7450 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7452 raw_spin_lock(&rt_rq->rt_runtime_lock);
7453 rt_rq->rt_runtime = global_rt_runtime();
7454 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7456 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7460 #endif /* CONFIG_RT_GROUP_SCHED */
7462 static int sched_dl_global_constraints(void)
7464 u64 runtime = global_rt_runtime();
7465 u64 period = global_rt_period();
7466 u64 new_bw = to_ratio(period, runtime);
7468 unsigned long flags;
7471 * Here we want to check the bandwidth not being set to some
7472 * value smaller than the currently allocated bandwidth in
7473 * any of the root_domains.
7475 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7476 * cycling on root_domains... Discussion on different/better
7477 * solutions is welcome!
7479 for_each_possible_cpu(cpu) {
7480 struct dl_bw *dl_b = dl_bw_of(cpu);
7482 raw_spin_lock_irqsave(&dl_b->lock, flags);
7483 if (new_bw < dl_b->total_bw)
7485 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7494 static void sched_dl_do_global(void)
7498 unsigned long flags;
7500 def_dl_bandwidth.dl_period = global_rt_period();
7501 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7503 if (global_rt_runtime() != RUNTIME_INF)
7504 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7507 * FIXME: As above...
7509 for_each_possible_cpu(cpu) {
7510 struct dl_bw *dl_b = dl_bw_of(cpu);
7512 raw_spin_lock_irqsave(&dl_b->lock, flags);
7514 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7518 static int sched_rt_global_validate(void)
7520 if (sysctl_sched_rt_period <= 0)
7523 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7524 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7530 static void sched_rt_do_global(void)
7532 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7533 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7536 int sched_rt_handler(struct ctl_table *table, int write,
7537 void __user *buffer, size_t *lenp,
7540 int old_period, old_runtime;
7541 static DEFINE_MUTEX(mutex);
7545 old_period = sysctl_sched_rt_period;
7546 old_runtime = sysctl_sched_rt_runtime;
7548 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7550 if (!ret && write) {
7551 ret = sched_rt_global_validate();
7555 ret = sched_rt_global_constraints();
7559 ret = sched_dl_global_constraints();
7563 sched_rt_do_global();
7564 sched_dl_do_global();
7568 sysctl_sched_rt_period = old_period;
7569 sysctl_sched_rt_runtime = old_runtime;
7571 mutex_unlock(&mutex);
7576 int sched_rr_handler(struct ctl_table *table, int write,
7577 void __user *buffer, size_t *lenp,
7581 static DEFINE_MUTEX(mutex);
7584 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7585 /* make sure that internally we keep jiffies */
7586 /* also, writing zero resets timeslice to default */
7587 if (!ret && write) {
7588 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
7589 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
7591 mutex_unlock(&mutex);
7595 #ifdef CONFIG_CGROUP_SCHED
7597 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
7599 return css ? container_of(css, struct task_group, css) : NULL;
7602 static struct cgroup_subsys_state *
7603 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
7605 struct task_group *parent = css_tg(parent_css);
7606 struct task_group *tg;
7609 /* This is early initialization for the top cgroup */
7610 return &root_task_group.css;
7613 tg = sched_create_group(parent);
7615 return ERR_PTR(-ENOMEM);
7620 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
7622 struct task_group *tg = css_tg(css);
7623 struct task_group *parent = css_tg(css_parent(css));
7626 sched_online_group(tg, parent);
7630 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
7632 struct task_group *tg = css_tg(css);
7634 sched_destroy_group(tg);
7637 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
7639 struct task_group *tg = css_tg(css);
7641 sched_offline_group(tg);
7644 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
7645 struct cgroup_taskset *tset)
7647 struct task_struct *task;
7649 cgroup_taskset_for_each(task, tset) {
7650 #ifdef CONFIG_RT_GROUP_SCHED
7651 if (!sched_rt_can_attach(css_tg(css), task))
7654 /* We don't support RT-tasks being in separate groups */
7655 if (task->sched_class != &fair_sched_class)
7662 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
7663 struct cgroup_taskset *tset)
7665 struct task_struct *task;
7667 cgroup_taskset_for_each(task, tset)
7668 sched_move_task(task);
7671 static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7672 struct cgroup_subsys_state *old_css,
7673 struct task_struct *task)
7676 * cgroup_exit() is called in the copy_process() failure path.
7677 * Ignore this case since the task hasn't ran yet, this avoids
7678 * trying to poke a half freed task state from generic code.
7680 if (!(task->flags & PF_EXITING))
7683 sched_move_task(task);
7686 #ifdef CONFIG_FAIR_GROUP_SCHED
7687 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7688 struct cftype *cftype, u64 shareval)
7690 return sched_group_set_shares(css_tg(css), scale_load(shareval));
7693 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7696 struct task_group *tg = css_tg(css);
7698 return (u64) scale_load_down(tg->shares);
7701 #ifdef CONFIG_CFS_BANDWIDTH
7702 static DEFINE_MUTEX(cfs_constraints_mutex);
7704 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7705 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7707 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7709 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7711 int i, ret = 0, runtime_enabled, runtime_was_enabled;
7712 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7714 if (tg == &root_task_group)
7718 * Ensure we have at some amount of bandwidth every period. This is
7719 * to prevent reaching a state of large arrears when throttled via
7720 * entity_tick() resulting in prolonged exit starvation.
7722 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7726 * Likewise, bound things on the otherside by preventing insane quota
7727 * periods. This also allows us to normalize in computing quota
7730 if (period > max_cfs_quota_period)
7733 mutex_lock(&cfs_constraints_mutex);
7734 ret = __cfs_schedulable(tg, period, quota);
7738 runtime_enabled = quota != RUNTIME_INF;
7739 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7741 * If we need to toggle cfs_bandwidth_used, off->on must occur
7742 * before making related changes, and on->off must occur afterwards
7744 if (runtime_enabled && !runtime_was_enabled)
7745 cfs_bandwidth_usage_inc();
7746 raw_spin_lock_irq(&cfs_b->lock);
7747 cfs_b->period = ns_to_ktime(period);
7748 cfs_b->quota = quota;
7750 __refill_cfs_bandwidth_runtime(cfs_b);
7751 /* restart the period timer (if active) to handle new period expiry */
7752 if (runtime_enabled && cfs_b->timer_active) {
7753 /* force a reprogram */
7754 __start_cfs_bandwidth(cfs_b, true);
7756 raw_spin_unlock_irq(&cfs_b->lock);
7758 for_each_possible_cpu(i) {
7759 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7760 struct rq *rq = cfs_rq->rq;
7762 raw_spin_lock_irq(&rq->lock);
7763 cfs_rq->runtime_enabled = runtime_enabled;
7764 cfs_rq->runtime_remaining = 0;
7766 if (cfs_rq->throttled)
7767 unthrottle_cfs_rq(cfs_rq);
7768 raw_spin_unlock_irq(&rq->lock);
7770 if (runtime_was_enabled && !runtime_enabled)
7771 cfs_bandwidth_usage_dec();
7773 mutex_unlock(&cfs_constraints_mutex);
7778 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7782 period = ktime_to_ns(tg->cfs_bandwidth.period);
7783 if (cfs_quota_us < 0)
7784 quota = RUNTIME_INF;
7786 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7788 return tg_set_cfs_bandwidth(tg, period, quota);
7791 long tg_get_cfs_quota(struct task_group *tg)
7795 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7798 quota_us = tg->cfs_bandwidth.quota;
7799 do_div(quota_us, NSEC_PER_USEC);
7804 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
7808 period = (u64)cfs_period_us * NSEC_PER_USEC;
7809 quota = tg->cfs_bandwidth.quota;
7811 return tg_set_cfs_bandwidth(tg, period, quota);
7814 long tg_get_cfs_period(struct task_group *tg)
7818 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
7819 do_div(cfs_period_us, NSEC_PER_USEC);
7821 return cfs_period_us;
7824 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
7827 return tg_get_cfs_quota(css_tg(css));
7830 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
7831 struct cftype *cftype, s64 cfs_quota_us)
7833 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
7836 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
7839 return tg_get_cfs_period(css_tg(css));
7842 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
7843 struct cftype *cftype, u64 cfs_period_us)
7845 return tg_set_cfs_period(css_tg(css), cfs_period_us);
7848 struct cfs_schedulable_data {
7849 struct task_group *tg;
7854 * normalize group quota/period to be quota/max_period
7855 * note: units are usecs
7857 static u64 normalize_cfs_quota(struct task_group *tg,
7858 struct cfs_schedulable_data *d)
7866 period = tg_get_cfs_period(tg);
7867 quota = tg_get_cfs_quota(tg);
7870 /* note: these should typically be equivalent */
7871 if (quota == RUNTIME_INF || quota == -1)
7874 return to_ratio(period, quota);
7877 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
7879 struct cfs_schedulable_data *d = data;
7880 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7881 s64 quota = 0, parent_quota = -1;
7884 quota = RUNTIME_INF;
7886 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
7888 quota = normalize_cfs_quota(tg, d);
7889 parent_quota = parent_b->hierarchal_quota;
7892 * ensure max(child_quota) <= parent_quota, inherit when no
7895 if (quota == RUNTIME_INF)
7896 quota = parent_quota;
7897 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
7900 cfs_b->hierarchal_quota = quota;
7905 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
7908 struct cfs_schedulable_data data = {
7914 if (quota != RUNTIME_INF) {
7915 do_div(data.period, NSEC_PER_USEC);
7916 do_div(data.quota, NSEC_PER_USEC);
7920 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
7926 static int cpu_stats_show(struct seq_file *sf, void *v)
7928 struct task_group *tg = css_tg(seq_css(sf));
7929 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7931 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
7932 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
7933 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
7937 #endif /* CONFIG_CFS_BANDWIDTH */
7938 #endif /* CONFIG_FAIR_GROUP_SCHED */
7940 #ifdef CONFIG_RT_GROUP_SCHED
7941 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
7942 struct cftype *cft, s64 val)
7944 return sched_group_set_rt_runtime(css_tg(css), val);
7947 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
7950 return sched_group_rt_runtime(css_tg(css));
7953 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
7954 struct cftype *cftype, u64 rt_period_us)
7956 return sched_group_set_rt_period(css_tg(css), rt_period_us);
7959 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
7962 return sched_group_rt_period(css_tg(css));
7964 #endif /* CONFIG_RT_GROUP_SCHED */
7966 static struct cftype cpu_files[] = {
7967 #ifdef CONFIG_FAIR_GROUP_SCHED
7970 .read_u64 = cpu_shares_read_u64,
7971 .write_u64 = cpu_shares_write_u64,
7974 #ifdef CONFIG_CFS_BANDWIDTH
7976 .name = "cfs_quota_us",
7977 .read_s64 = cpu_cfs_quota_read_s64,
7978 .write_s64 = cpu_cfs_quota_write_s64,
7981 .name = "cfs_period_us",
7982 .read_u64 = cpu_cfs_period_read_u64,
7983 .write_u64 = cpu_cfs_period_write_u64,
7987 .seq_show = cpu_stats_show,
7990 #ifdef CONFIG_RT_GROUP_SCHED
7992 .name = "rt_runtime_us",
7993 .read_s64 = cpu_rt_runtime_read,
7994 .write_s64 = cpu_rt_runtime_write,
7997 .name = "rt_period_us",
7998 .read_u64 = cpu_rt_period_read_uint,
7999 .write_u64 = cpu_rt_period_write_uint,
8005 struct cgroup_subsys cpu_cgrp_subsys = {
8006 .css_alloc = cpu_cgroup_css_alloc,
8007 .css_free = cpu_cgroup_css_free,
8008 .css_online = cpu_cgroup_css_online,
8009 .css_offline = cpu_cgroup_css_offline,
8010 .can_attach = cpu_cgroup_can_attach,
8011 .attach = cpu_cgroup_attach,
8012 .exit = cpu_cgroup_exit,
8013 .base_cftypes = cpu_files,
8017 #endif /* CONFIG_CGROUP_SCHED */
8019 void dump_cpu_task(int cpu)
8021 pr_info("Task dump for CPU %d:\n", cpu);
8022 sched_show_task(cpu_curr(cpu));