4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/debugfs.h>
70 #include <linux/ctype.h>
71 #include <linux/ftrace.h>
72 #include <linux/slab.h>
73 #include <linux/init_task.h>
74 #include <linux/binfmts.h>
75 #include <linux/context_tracking.h>
76 #include <linux/compiler.h>
78 #include <asm/switch_to.h>
80 #include <asm/irq_regs.h>
81 #include <asm/mutex.h>
82 #ifdef CONFIG_PARAVIRT
83 #include <asm/paravirt.h>
87 #include "../workqueue_internal.h"
88 #include "../smpboot.h"
90 #define CREATE_TRACE_POINTS
91 #include <trace/events/sched.h>
93 #ifdef smp_mb__before_atomic
94 void __smp_mb__before_atomic(void)
96 smp_mb__before_atomic();
98 EXPORT_SYMBOL(__smp_mb__before_atomic);
101 #ifdef smp_mb__after_atomic
102 void __smp_mb__after_atomic(void)
104 smp_mb__after_atomic();
106 EXPORT_SYMBOL(__smp_mb__after_atomic);
109 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
112 ktime_t soft, hard, now;
115 if (hrtimer_active(period_timer))
118 now = hrtimer_cb_get_time(period_timer);
119 hrtimer_forward(period_timer, now, period);
121 soft = hrtimer_get_softexpires(period_timer);
122 hard = hrtimer_get_expires(period_timer);
123 delta = ktime_to_ns(ktime_sub(hard, soft));
124 __hrtimer_start_range_ns(period_timer, soft, delta,
125 HRTIMER_MODE_ABS_PINNED, 0);
129 DEFINE_MUTEX(sched_domains_mutex);
130 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
132 static void update_rq_clock_task(struct rq *rq, s64 delta);
134 void update_rq_clock(struct rq *rq)
138 if (rq->skip_clock_update > 0)
141 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
143 update_rq_clock_task(rq, delta);
147 * Debugging: various feature bits
150 #define SCHED_FEAT(name, enabled) \
151 (1UL << __SCHED_FEAT_##name) * enabled |
153 const_debug unsigned int sysctl_sched_features =
154 #include "features.h"
159 #ifdef CONFIG_SCHED_DEBUG
160 #define SCHED_FEAT(name, enabled) \
163 static const char * const sched_feat_names[] = {
164 #include "features.h"
169 static int sched_feat_show(struct seq_file *m, void *v)
173 for (i = 0; i < __SCHED_FEAT_NR; i++) {
174 if (!(sysctl_sched_features & (1UL << i)))
176 seq_printf(m, "%s ", sched_feat_names[i]);
183 #ifdef HAVE_JUMP_LABEL
185 #define jump_label_key__true STATIC_KEY_INIT_TRUE
186 #define jump_label_key__false STATIC_KEY_INIT_FALSE
188 #define SCHED_FEAT(name, enabled) \
189 jump_label_key__##enabled ,
191 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
192 #include "features.h"
197 static void sched_feat_disable(int i)
199 if (static_key_enabled(&sched_feat_keys[i]))
200 static_key_slow_dec(&sched_feat_keys[i]);
203 static void sched_feat_enable(int i)
205 if (!static_key_enabled(&sched_feat_keys[i]))
206 static_key_slow_inc(&sched_feat_keys[i]);
209 static void sched_feat_disable(int i) { };
210 static void sched_feat_enable(int i) { };
211 #endif /* HAVE_JUMP_LABEL */
213 static int sched_feat_set(char *cmp)
218 if (strncmp(cmp, "NO_", 3) == 0) {
223 for (i = 0; i < __SCHED_FEAT_NR; i++) {
224 if (strcmp(cmp, sched_feat_names[i]) == 0) {
226 sysctl_sched_features &= ~(1UL << i);
227 sched_feat_disable(i);
229 sysctl_sched_features |= (1UL << i);
230 sched_feat_enable(i);
240 sched_feat_write(struct file *filp, const char __user *ubuf,
241 size_t cnt, loff_t *ppos)
250 if (copy_from_user(&buf, ubuf, cnt))
256 i = sched_feat_set(cmp);
257 if (i == __SCHED_FEAT_NR)
265 static int sched_feat_open(struct inode *inode, struct file *filp)
267 return single_open(filp, sched_feat_show, NULL);
270 static const struct file_operations sched_feat_fops = {
271 .open = sched_feat_open,
272 .write = sched_feat_write,
275 .release = single_release,
278 static __init int sched_init_debug(void)
280 debugfs_create_file("sched_features", 0644, NULL, NULL,
285 late_initcall(sched_init_debug);
286 #endif /* CONFIG_SCHED_DEBUG */
289 * Number of tasks to iterate in a single balance run.
290 * Limited because this is done with IRQs disabled.
292 const_debug unsigned int sysctl_sched_nr_migrate = 32;
295 * period over which we average the RT time consumption, measured
300 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
303 * period over which we measure -rt task cpu usage in us.
306 unsigned int sysctl_sched_rt_period = 1000000;
308 __read_mostly int scheduler_running;
311 * part of the period that we allow rt tasks to run in us.
314 int sysctl_sched_rt_runtime = 950000;
317 * __task_rq_lock - lock the rq @p resides on.
319 static inline struct rq *__task_rq_lock(struct task_struct *p)
324 lockdep_assert_held(&p->pi_lock);
328 raw_spin_lock(&rq->lock);
329 if (likely(rq == task_rq(p)))
331 raw_spin_unlock(&rq->lock);
336 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
338 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
339 __acquires(p->pi_lock)
345 raw_spin_lock_irqsave(&p->pi_lock, *flags);
347 raw_spin_lock(&rq->lock);
348 if (likely(rq == task_rq(p)))
350 raw_spin_unlock(&rq->lock);
351 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
355 static void __task_rq_unlock(struct rq *rq)
358 raw_spin_unlock(&rq->lock);
362 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
364 __releases(p->pi_lock)
366 raw_spin_unlock(&rq->lock);
367 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
371 * this_rq_lock - lock this runqueue and disable interrupts.
373 static struct rq *this_rq_lock(void)
380 raw_spin_lock(&rq->lock);
385 #ifdef CONFIG_SCHED_HRTICK
387 * Use HR-timers to deliver accurate preemption points.
390 static void hrtick_clear(struct rq *rq)
392 if (hrtimer_active(&rq->hrtick_timer))
393 hrtimer_cancel(&rq->hrtick_timer);
397 * High-resolution timer tick.
398 * Runs from hardirq context with interrupts disabled.
400 static enum hrtimer_restart hrtick(struct hrtimer *timer)
402 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
404 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
406 raw_spin_lock(&rq->lock);
408 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
409 raw_spin_unlock(&rq->lock);
411 return HRTIMER_NORESTART;
416 static int __hrtick_restart(struct rq *rq)
418 struct hrtimer *timer = &rq->hrtick_timer;
419 ktime_t time = hrtimer_get_softexpires(timer);
421 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
425 * called from hardirq (IPI) context
427 static void __hrtick_start(void *arg)
431 raw_spin_lock(&rq->lock);
432 __hrtick_restart(rq);
433 rq->hrtick_csd_pending = 0;
434 raw_spin_unlock(&rq->lock);
438 * Called to set the hrtick timer state.
440 * called with rq->lock held and irqs disabled
442 void hrtick_start(struct rq *rq, u64 delay)
444 struct hrtimer *timer = &rq->hrtick_timer;
445 ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
447 hrtimer_set_expires(timer, time);
449 if (rq == this_rq()) {
450 __hrtick_restart(rq);
451 } else if (!rq->hrtick_csd_pending) {
452 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
453 rq->hrtick_csd_pending = 1;
458 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
460 int cpu = (int)(long)hcpu;
463 case CPU_UP_CANCELED:
464 case CPU_UP_CANCELED_FROZEN:
465 case CPU_DOWN_PREPARE:
466 case CPU_DOWN_PREPARE_FROZEN:
468 case CPU_DEAD_FROZEN:
469 hrtick_clear(cpu_rq(cpu));
476 static __init void init_hrtick(void)
478 hotcpu_notifier(hotplug_hrtick, 0);
482 * Called to set the hrtick timer state.
484 * called with rq->lock held and irqs disabled
486 void hrtick_start(struct rq *rq, u64 delay)
488 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
489 HRTIMER_MODE_REL_PINNED, 0);
492 static inline void init_hrtick(void)
495 #endif /* CONFIG_SMP */
497 static void init_rq_hrtick(struct rq *rq)
500 rq->hrtick_csd_pending = 0;
502 rq->hrtick_csd.flags = 0;
503 rq->hrtick_csd.func = __hrtick_start;
504 rq->hrtick_csd.info = rq;
507 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
508 rq->hrtick_timer.function = hrtick;
510 #else /* CONFIG_SCHED_HRTICK */
511 static inline void hrtick_clear(struct rq *rq)
515 static inline void init_rq_hrtick(struct rq *rq)
519 static inline void init_hrtick(void)
522 #endif /* CONFIG_SCHED_HRTICK */
525 * cmpxchg based fetch_or, macro so it works for different integer types
527 #define fetch_or(ptr, val) \
528 ({ typeof(*(ptr)) __old, __val = *(ptr); \
530 __old = cmpxchg((ptr), __val, __val | (val)); \
531 if (__old == __val) \
538 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
540 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
541 * this avoids any races wrt polling state changes and thereby avoids
544 static bool set_nr_and_not_polling(struct task_struct *p)
546 struct thread_info *ti = task_thread_info(p);
547 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
551 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
553 * If this returns true, then the idle task promises to call
554 * sched_ttwu_pending() and reschedule soon.
556 static bool set_nr_if_polling(struct task_struct *p)
558 struct thread_info *ti = task_thread_info(p);
559 typeof(ti->flags) old, val = ACCESS_ONCE(ti->flags);
562 if (!(val & _TIF_POLLING_NRFLAG))
564 if (val & _TIF_NEED_RESCHED)
566 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
575 static bool set_nr_and_not_polling(struct task_struct *p)
577 set_tsk_need_resched(p);
582 static bool set_nr_if_polling(struct task_struct *p)
590 * resched_task - mark a task 'to be rescheduled now'.
592 * On UP this means the setting of the need_resched flag, on SMP it
593 * might also involve a cross-CPU call to trigger the scheduler on
596 void resched_task(struct task_struct *p)
600 lockdep_assert_held(&task_rq(p)->lock);
602 if (test_tsk_need_resched(p))
607 if (cpu == smp_processor_id()) {
608 set_tsk_need_resched(p);
609 set_preempt_need_resched();
613 if (set_nr_and_not_polling(p))
614 smp_send_reschedule(cpu);
616 trace_sched_wake_idle_without_ipi(cpu);
619 void resched_cpu(int cpu)
621 struct rq *rq = cpu_rq(cpu);
624 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
626 resched_task(cpu_curr(cpu));
627 raw_spin_unlock_irqrestore(&rq->lock, flags);
631 #ifdef CONFIG_NO_HZ_COMMON
633 * In the semi idle case, use the nearest busy cpu for migrating timers
634 * from an idle cpu. This is good for power-savings.
636 * We don't do similar optimization for completely idle system, as
637 * selecting an idle cpu will add more delays to the timers than intended
638 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
640 int get_nohz_timer_target(int pinned)
642 int cpu = smp_processor_id();
644 struct sched_domain *sd;
646 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
650 for_each_domain(cpu, sd) {
651 for_each_cpu(i, sched_domain_span(sd)) {
663 * When add_timer_on() enqueues a timer into the timer wheel of an
664 * idle CPU then this timer might expire before the next timer event
665 * which is scheduled to wake up that CPU. In case of a completely
666 * idle system the next event might even be infinite time into the
667 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
668 * leaves the inner idle loop so the newly added timer is taken into
669 * account when the CPU goes back to idle and evaluates the timer
670 * wheel for the next timer event.
672 static void wake_up_idle_cpu(int cpu)
674 struct rq *rq = cpu_rq(cpu);
676 if (cpu == smp_processor_id())
679 if (set_nr_and_not_polling(rq->idle))
680 smp_send_reschedule(cpu);
682 trace_sched_wake_idle_without_ipi(cpu);
685 static bool wake_up_full_nohz_cpu(int cpu)
687 if (tick_nohz_full_cpu(cpu)) {
688 if (cpu != smp_processor_id() ||
689 tick_nohz_tick_stopped())
690 smp_send_reschedule(cpu);
697 void wake_up_nohz_cpu(int cpu)
699 if (!wake_up_full_nohz_cpu(cpu))
700 wake_up_idle_cpu(cpu);
703 static inline bool got_nohz_idle_kick(void)
705 int cpu = smp_processor_id();
707 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
710 if (idle_cpu(cpu) && !need_resched())
714 * We can't run Idle Load Balance on this CPU for this time so we
715 * cancel it and clear NOHZ_BALANCE_KICK
717 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
721 #else /* CONFIG_NO_HZ_COMMON */
723 static inline bool got_nohz_idle_kick(void)
728 #endif /* CONFIG_NO_HZ_COMMON */
730 #ifdef CONFIG_NO_HZ_FULL
731 bool sched_can_stop_tick(void)
737 /* Make sure rq->nr_running update is visible after the IPI */
740 /* More than one running task need preemption */
741 if (rq->nr_running > 1)
746 #endif /* CONFIG_NO_HZ_FULL */
748 void sched_avg_update(struct rq *rq)
750 s64 period = sched_avg_period();
752 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
754 * Inline assembly required to prevent the compiler
755 * optimising this loop into a divmod call.
756 * See __iter_div_u64_rem() for another example of this.
758 asm("" : "+rm" (rq->age_stamp));
759 rq->age_stamp += period;
764 #endif /* CONFIG_SMP */
766 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
767 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
769 * Iterate task_group tree rooted at *from, calling @down when first entering a
770 * node and @up when leaving it for the final time.
772 * Caller must hold rcu_lock or sufficient equivalent.
774 int walk_tg_tree_from(struct task_group *from,
775 tg_visitor down, tg_visitor up, void *data)
777 struct task_group *parent, *child;
783 ret = (*down)(parent, data);
786 list_for_each_entry_rcu(child, &parent->children, siblings) {
793 ret = (*up)(parent, data);
794 if (ret || parent == from)
798 parent = parent->parent;
805 int tg_nop(struct task_group *tg, void *data)
811 static void set_load_weight(struct task_struct *p)
813 int prio = p->static_prio - MAX_RT_PRIO;
814 struct load_weight *load = &p->se.load;
817 * SCHED_IDLE tasks get minimal weight:
819 if (p->policy == SCHED_IDLE) {
820 load->weight = scale_load(WEIGHT_IDLEPRIO);
821 load->inv_weight = WMULT_IDLEPRIO;
825 load->weight = scale_load(prio_to_weight[prio]);
826 load->inv_weight = prio_to_wmult[prio];
829 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
832 sched_info_queued(rq, p);
833 p->sched_class->enqueue_task(rq, p, flags);
836 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
839 sched_info_dequeued(rq, p);
840 p->sched_class->dequeue_task(rq, p, flags);
843 void activate_task(struct rq *rq, struct task_struct *p, int flags)
845 if (task_contributes_to_load(p))
846 rq->nr_uninterruptible--;
848 enqueue_task(rq, p, flags);
851 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
853 if (task_contributes_to_load(p))
854 rq->nr_uninterruptible++;
856 dequeue_task(rq, p, flags);
859 static void update_rq_clock_task(struct rq *rq, s64 delta)
862 * In theory, the compile should just see 0 here, and optimize out the call
863 * to sched_rt_avg_update. But I don't trust it...
865 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
866 s64 steal = 0, irq_delta = 0;
868 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
869 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
872 * Since irq_time is only updated on {soft,}irq_exit, we might run into
873 * this case when a previous update_rq_clock() happened inside a
876 * When this happens, we stop ->clock_task and only update the
877 * prev_irq_time stamp to account for the part that fit, so that a next
878 * update will consume the rest. This ensures ->clock_task is
881 * It does however cause some slight miss-attribution of {soft,}irq
882 * time, a more accurate solution would be to update the irq_time using
883 * the current rq->clock timestamp, except that would require using
886 if (irq_delta > delta)
889 rq->prev_irq_time += irq_delta;
892 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
893 if (static_key_false((¶virt_steal_rq_enabled))) {
894 steal = paravirt_steal_clock(cpu_of(rq));
895 steal -= rq->prev_steal_time_rq;
897 if (unlikely(steal > delta))
900 rq->prev_steal_time_rq += steal;
905 rq->clock_task += delta;
907 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
908 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
909 sched_rt_avg_update(rq, irq_delta + steal);
913 void sched_set_stop_task(int cpu, struct task_struct *stop)
915 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
916 struct task_struct *old_stop = cpu_rq(cpu)->stop;
920 * Make it appear like a SCHED_FIFO task, its something
921 * userspace knows about and won't get confused about.
923 * Also, it will make PI more or less work without too
924 * much confusion -- but then, stop work should not
925 * rely on PI working anyway.
927 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
929 stop->sched_class = &stop_sched_class;
932 cpu_rq(cpu)->stop = stop;
936 * Reset it back to a normal scheduling class so that
937 * it can die in pieces.
939 old_stop->sched_class = &rt_sched_class;
944 * __normal_prio - return the priority that is based on the static prio
946 static inline int __normal_prio(struct task_struct *p)
948 return p->static_prio;
952 * Calculate the expected normal priority: i.e. priority
953 * without taking RT-inheritance into account. Might be
954 * boosted by interactivity modifiers. Changes upon fork,
955 * setprio syscalls, and whenever the interactivity
956 * estimator recalculates.
958 static inline int normal_prio(struct task_struct *p)
962 if (task_has_dl_policy(p))
963 prio = MAX_DL_PRIO-1;
964 else if (task_has_rt_policy(p))
965 prio = MAX_RT_PRIO-1 - p->rt_priority;
967 prio = __normal_prio(p);
972 * Calculate the current priority, i.e. the priority
973 * taken into account by the scheduler. This value might
974 * be boosted by RT tasks, or might be boosted by
975 * interactivity modifiers. Will be RT if the task got
976 * RT-boosted. If not then it returns p->normal_prio.
978 static int effective_prio(struct task_struct *p)
980 p->normal_prio = normal_prio(p);
982 * If we are RT tasks or we were boosted to RT priority,
983 * keep the priority unchanged. Otherwise, update priority
984 * to the normal priority:
986 if (!rt_prio(p->prio))
987 return p->normal_prio;
992 * task_curr - is this task currently executing on a CPU?
993 * @p: the task in question.
995 * Return: 1 if the task is currently executing. 0 otherwise.
997 inline int task_curr(const struct task_struct *p)
999 return cpu_curr(task_cpu(p)) == p;
1002 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1003 const struct sched_class *prev_class,
1006 if (prev_class != p->sched_class) {
1007 if (prev_class->switched_from)
1008 prev_class->switched_from(rq, p);
1009 p->sched_class->switched_to(rq, p);
1010 } else if (oldprio != p->prio || dl_task(p))
1011 p->sched_class->prio_changed(rq, p, oldprio);
1014 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
1016 const struct sched_class *class;
1018 if (p->sched_class == rq->curr->sched_class) {
1019 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
1021 for_each_class(class) {
1022 if (class == rq->curr->sched_class)
1024 if (class == p->sched_class) {
1025 resched_task(rq->curr);
1032 * A queue event has occurred, and we're going to schedule. In
1033 * this case, we can save a useless back to back clock update.
1035 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
1036 rq->skip_clock_update = 1;
1040 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1042 #ifdef CONFIG_SCHED_DEBUG
1044 * We should never call set_task_cpu() on a blocked task,
1045 * ttwu() will sort out the placement.
1047 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1048 !(task_preempt_count(p) & PREEMPT_ACTIVE));
1050 #ifdef CONFIG_LOCKDEP
1052 * The caller should hold either p->pi_lock or rq->lock, when changing
1053 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1055 * sched_move_task() holds both and thus holding either pins the cgroup,
1058 * Furthermore, all task_rq users should acquire both locks, see
1061 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1062 lockdep_is_held(&task_rq(p)->lock)));
1066 trace_sched_migrate_task(p, new_cpu);
1068 if (task_cpu(p) != new_cpu) {
1069 if (p->sched_class->migrate_task_rq)
1070 p->sched_class->migrate_task_rq(p, new_cpu);
1071 p->se.nr_migrations++;
1072 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1075 __set_task_cpu(p, new_cpu);
1078 static void __migrate_swap_task(struct task_struct *p, int cpu)
1081 struct rq *src_rq, *dst_rq;
1083 src_rq = task_rq(p);
1084 dst_rq = cpu_rq(cpu);
1086 deactivate_task(src_rq, p, 0);
1087 set_task_cpu(p, cpu);
1088 activate_task(dst_rq, p, 0);
1089 check_preempt_curr(dst_rq, p, 0);
1092 * Task isn't running anymore; make it appear like we migrated
1093 * it before it went to sleep. This means on wakeup we make the
1094 * previous cpu our targer instead of where it really is.
1100 struct migration_swap_arg {
1101 struct task_struct *src_task, *dst_task;
1102 int src_cpu, dst_cpu;
1105 static int migrate_swap_stop(void *data)
1107 struct migration_swap_arg *arg = data;
1108 struct rq *src_rq, *dst_rq;
1111 src_rq = cpu_rq(arg->src_cpu);
1112 dst_rq = cpu_rq(arg->dst_cpu);
1114 double_raw_lock(&arg->src_task->pi_lock,
1115 &arg->dst_task->pi_lock);
1116 double_rq_lock(src_rq, dst_rq);
1117 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1120 if (task_cpu(arg->src_task) != arg->src_cpu)
1123 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1126 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1129 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1130 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1135 double_rq_unlock(src_rq, dst_rq);
1136 raw_spin_unlock(&arg->dst_task->pi_lock);
1137 raw_spin_unlock(&arg->src_task->pi_lock);
1143 * Cross migrate two tasks
1145 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1147 struct migration_swap_arg arg;
1150 arg = (struct migration_swap_arg){
1152 .src_cpu = task_cpu(cur),
1154 .dst_cpu = task_cpu(p),
1157 if (arg.src_cpu == arg.dst_cpu)
1161 * These three tests are all lockless; this is OK since all of them
1162 * will be re-checked with proper locks held further down the line.
1164 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1167 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1170 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1173 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1174 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1180 struct migration_arg {
1181 struct task_struct *task;
1185 static int migration_cpu_stop(void *data);
1188 * wait_task_inactive - wait for a thread to unschedule.
1190 * If @match_state is nonzero, it's the @p->state value just checked and
1191 * not expected to change. If it changes, i.e. @p might have woken up,
1192 * then return zero. When we succeed in waiting for @p to be off its CPU,
1193 * we return a positive number (its total switch count). If a second call
1194 * a short while later returns the same number, the caller can be sure that
1195 * @p has remained unscheduled the whole time.
1197 * The caller must ensure that the task *will* unschedule sometime soon,
1198 * else this function might spin for a *long* time. This function can't
1199 * be called with interrupts off, or it may introduce deadlock with
1200 * smp_call_function() if an IPI is sent by the same process we are
1201 * waiting to become inactive.
1203 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1205 unsigned long flags;
1212 * We do the initial early heuristics without holding
1213 * any task-queue locks at all. We'll only try to get
1214 * the runqueue lock when things look like they will
1220 * If the task is actively running on another CPU
1221 * still, just relax and busy-wait without holding
1224 * NOTE! Since we don't hold any locks, it's not
1225 * even sure that "rq" stays as the right runqueue!
1226 * But we don't care, since "task_running()" will
1227 * return false if the runqueue has changed and p
1228 * is actually now running somewhere else!
1230 while (task_running(rq, p)) {
1231 if (match_state && unlikely(p->state != match_state))
1237 * Ok, time to look more closely! We need the rq
1238 * lock now, to be *sure*. If we're wrong, we'll
1239 * just go back and repeat.
1241 rq = task_rq_lock(p, &flags);
1242 trace_sched_wait_task(p);
1243 running = task_running(rq, p);
1246 if (!match_state || p->state == match_state)
1247 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1248 task_rq_unlock(rq, p, &flags);
1251 * If it changed from the expected state, bail out now.
1253 if (unlikely(!ncsw))
1257 * Was it really running after all now that we
1258 * checked with the proper locks actually held?
1260 * Oops. Go back and try again..
1262 if (unlikely(running)) {
1268 * It's not enough that it's not actively running,
1269 * it must be off the runqueue _entirely_, and not
1272 * So if it was still runnable (but just not actively
1273 * running right now), it's preempted, and we should
1274 * yield - it could be a while.
1276 if (unlikely(on_rq)) {
1277 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1279 set_current_state(TASK_UNINTERRUPTIBLE);
1280 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1285 * Ahh, all good. It wasn't running, and it wasn't
1286 * runnable, which means that it will never become
1287 * running in the future either. We're all done!
1296 * kick_process - kick a running thread to enter/exit the kernel
1297 * @p: the to-be-kicked thread
1299 * Cause a process which is running on another CPU to enter
1300 * kernel-mode, without any delay. (to get signals handled.)
1302 * NOTE: this function doesn't have to take the runqueue lock,
1303 * because all it wants to ensure is that the remote task enters
1304 * the kernel. If the IPI races and the task has been migrated
1305 * to another CPU then no harm is done and the purpose has been
1308 void kick_process(struct task_struct *p)
1314 if ((cpu != smp_processor_id()) && task_curr(p))
1315 smp_send_reschedule(cpu);
1318 EXPORT_SYMBOL_GPL(kick_process);
1319 #endif /* CONFIG_SMP */
1323 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1325 static int select_fallback_rq(int cpu, struct task_struct *p)
1327 int nid = cpu_to_node(cpu);
1328 const struct cpumask *nodemask = NULL;
1329 enum { cpuset, possible, fail } state = cpuset;
1333 * If the node that the cpu is on has been offlined, cpu_to_node()
1334 * will return -1. There is no cpu on the node, and we should
1335 * select the cpu on the other node.
1338 nodemask = cpumask_of_node(nid);
1340 /* Look for allowed, online CPU in same node. */
1341 for_each_cpu(dest_cpu, nodemask) {
1342 if (!cpu_online(dest_cpu))
1344 if (!cpu_active(dest_cpu))
1346 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1352 /* Any allowed, online CPU? */
1353 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1354 if (!cpu_online(dest_cpu))
1356 if (!cpu_active(dest_cpu))
1363 /* No more Mr. Nice Guy. */
1364 cpuset_cpus_allowed_fallback(p);
1369 do_set_cpus_allowed(p, cpu_possible_mask);
1380 if (state != cpuset) {
1382 * Don't tell them about moving exiting tasks or
1383 * kernel threads (both mm NULL), since they never
1386 if (p->mm && printk_ratelimit()) {
1387 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1388 task_pid_nr(p), p->comm, cpu);
1396 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1399 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1401 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1404 * In order not to call set_task_cpu() on a blocking task we need
1405 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1408 * Since this is common to all placement strategies, this lives here.
1410 * [ this allows ->select_task() to simply return task_cpu(p) and
1411 * not worry about this generic constraint ]
1413 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1415 cpu = select_fallback_rq(task_cpu(p), p);
1420 static void update_avg(u64 *avg, u64 sample)
1422 s64 diff = sample - *avg;
1428 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1430 #ifdef CONFIG_SCHEDSTATS
1431 struct rq *rq = this_rq();
1434 int this_cpu = smp_processor_id();
1436 if (cpu == this_cpu) {
1437 schedstat_inc(rq, ttwu_local);
1438 schedstat_inc(p, se.statistics.nr_wakeups_local);
1440 struct sched_domain *sd;
1442 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1444 for_each_domain(this_cpu, sd) {
1445 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1446 schedstat_inc(sd, ttwu_wake_remote);
1453 if (wake_flags & WF_MIGRATED)
1454 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1456 #endif /* CONFIG_SMP */
1458 schedstat_inc(rq, ttwu_count);
1459 schedstat_inc(p, se.statistics.nr_wakeups);
1461 if (wake_flags & WF_SYNC)
1462 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1464 #endif /* CONFIG_SCHEDSTATS */
1467 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1469 activate_task(rq, p, en_flags);
1472 /* if a worker is waking up, notify workqueue */
1473 if (p->flags & PF_WQ_WORKER)
1474 wq_worker_waking_up(p, cpu_of(rq));
1478 * Mark the task runnable and perform wakeup-preemption.
1481 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1483 check_preempt_curr(rq, p, wake_flags);
1484 trace_sched_wakeup(p, true);
1486 p->state = TASK_RUNNING;
1488 if (p->sched_class->task_woken)
1489 p->sched_class->task_woken(rq, p);
1491 if (rq->idle_stamp) {
1492 u64 delta = rq_clock(rq) - rq->idle_stamp;
1493 u64 max = 2*rq->max_idle_balance_cost;
1495 update_avg(&rq->avg_idle, delta);
1497 if (rq->avg_idle > max)
1506 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1509 if (p->sched_contributes_to_load)
1510 rq->nr_uninterruptible--;
1513 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1514 ttwu_do_wakeup(rq, p, wake_flags);
1518 * Called in case the task @p isn't fully descheduled from its runqueue,
1519 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1520 * since all we need to do is flip p->state to TASK_RUNNING, since
1521 * the task is still ->on_rq.
1523 static int ttwu_remote(struct task_struct *p, int wake_flags)
1528 rq = __task_rq_lock(p);
1530 /* check_preempt_curr() may use rq clock */
1531 update_rq_clock(rq);
1532 ttwu_do_wakeup(rq, p, wake_flags);
1535 __task_rq_unlock(rq);
1541 void sched_ttwu_pending(void)
1543 struct rq *rq = this_rq();
1544 struct llist_node *llist = llist_del_all(&rq->wake_list);
1545 struct task_struct *p;
1546 unsigned long flags;
1551 raw_spin_lock_irqsave(&rq->lock, flags);
1554 p = llist_entry(llist, struct task_struct, wake_entry);
1555 llist = llist_next(llist);
1556 ttwu_do_activate(rq, p, 0);
1559 raw_spin_unlock_irqrestore(&rq->lock, flags);
1562 void scheduler_ipi(void)
1565 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1566 * TIF_NEED_RESCHED remotely (for the first time) will also send
1569 preempt_fold_need_resched();
1571 if (llist_empty(&this_rq()->wake_list)
1572 && !tick_nohz_full_cpu(smp_processor_id())
1573 && !got_nohz_idle_kick())
1577 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1578 * traditionally all their work was done from the interrupt return
1579 * path. Now that we actually do some work, we need to make sure
1582 * Some archs already do call them, luckily irq_enter/exit nest
1585 * Arguably we should visit all archs and update all handlers,
1586 * however a fair share of IPIs are still resched only so this would
1587 * somewhat pessimize the simple resched case.
1590 tick_nohz_full_check();
1591 sched_ttwu_pending();
1594 * Check if someone kicked us for doing the nohz idle load balance.
1596 if (unlikely(got_nohz_idle_kick())) {
1597 this_rq()->idle_balance = 1;
1598 raise_softirq_irqoff(SCHED_SOFTIRQ);
1603 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1605 struct rq *rq = cpu_rq(cpu);
1607 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1608 if (!set_nr_if_polling(rq->idle))
1609 smp_send_reschedule(cpu);
1611 trace_sched_wake_idle_without_ipi(cpu);
1615 bool cpus_share_cache(int this_cpu, int that_cpu)
1617 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1619 #endif /* CONFIG_SMP */
1621 static void ttwu_queue(struct task_struct *p, int cpu)
1623 struct rq *rq = cpu_rq(cpu);
1625 #if defined(CONFIG_SMP)
1626 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1627 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1628 ttwu_queue_remote(p, cpu);
1633 raw_spin_lock(&rq->lock);
1634 ttwu_do_activate(rq, p, 0);
1635 raw_spin_unlock(&rq->lock);
1639 * try_to_wake_up - wake up a thread
1640 * @p: the thread to be awakened
1641 * @state: the mask of task states that can be woken
1642 * @wake_flags: wake modifier flags (WF_*)
1644 * Put it on the run-queue if it's not already there. The "current"
1645 * thread is always on the run-queue (except when the actual
1646 * re-schedule is in progress), and as such you're allowed to do
1647 * the simpler "current->state = TASK_RUNNING" to mark yourself
1648 * runnable without the overhead of this.
1650 * Return: %true if @p was woken up, %false if it was already running.
1651 * or @state didn't match @p's state.
1654 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1656 unsigned long flags;
1657 int cpu, success = 0;
1660 * If we are going to wake up a thread waiting for CONDITION we
1661 * need to ensure that CONDITION=1 done by the caller can not be
1662 * reordered with p->state check below. This pairs with mb() in
1663 * set_current_state() the waiting thread does.
1665 smp_mb__before_spinlock();
1666 raw_spin_lock_irqsave(&p->pi_lock, flags);
1667 if (!(p->state & state))
1670 success = 1; /* we're going to change ->state */
1673 if (p->on_rq && ttwu_remote(p, wake_flags))
1678 * If the owning (remote) cpu is still in the middle of schedule() with
1679 * this task as prev, wait until its done referencing the task.
1684 * Pairs with the smp_wmb() in finish_lock_switch().
1688 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1689 p->state = TASK_WAKING;
1691 if (p->sched_class->task_waking)
1692 p->sched_class->task_waking(p);
1694 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1695 if (task_cpu(p) != cpu) {
1696 wake_flags |= WF_MIGRATED;
1697 set_task_cpu(p, cpu);
1699 #endif /* CONFIG_SMP */
1703 ttwu_stat(p, cpu, wake_flags);
1705 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1711 * try_to_wake_up_local - try to wake up a local task with rq lock held
1712 * @p: the thread to be awakened
1714 * Put @p on the run-queue if it's not already there. The caller must
1715 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1718 static void try_to_wake_up_local(struct task_struct *p)
1720 struct rq *rq = task_rq(p);
1722 if (WARN_ON_ONCE(rq != this_rq()) ||
1723 WARN_ON_ONCE(p == current))
1726 lockdep_assert_held(&rq->lock);
1728 if (!raw_spin_trylock(&p->pi_lock)) {
1729 raw_spin_unlock(&rq->lock);
1730 raw_spin_lock(&p->pi_lock);
1731 raw_spin_lock(&rq->lock);
1734 if (!(p->state & TASK_NORMAL))
1738 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1740 ttwu_do_wakeup(rq, p, 0);
1741 ttwu_stat(p, smp_processor_id(), 0);
1743 raw_spin_unlock(&p->pi_lock);
1747 * wake_up_process - Wake up a specific process
1748 * @p: The process to be woken up.
1750 * Attempt to wake up the nominated process and move it to the set of runnable
1753 * Return: 1 if the process was woken up, 0 if it was already running.
1755 * It may be assumed that this function implies a write memory barrier before
1756 * changing the task state if and only if any tasks are woken up.
1758 int wake_up_process(struct task_struct *p)
1760 WARN_ON(task_is_stopped_or_traced(p));
1761 return try_to_wake_up(p, TASK_NORMAL, 0);
1763 EXPORT_SYMBOL(wake_up_process);
1765 int wake_up_state(struct task_struct *p, unsigned int state)
1767 return try_to_wake_up(p, state, 0);
1771 * Perform scheduler related setup for a newly forked process p.
1772 * p is forked by current.
1774 * __sched_fork() is basic setup used by init_idle() too:
1776 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1781 p->se.exec_start = 0;
1782 p->se.sum_exec_runtime = 0;
1783 p->se.prev_sum_exec_runtime = 0;
1784 p->se.nr_migrations = 0;
1786 INIT_LIST_HEAD(&p->se.group_node);
1788 #ifdef CONFIG_SCHEDSTATS
1789 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1792 RB_CLEAR_NODE(&p->dl.rb_node);
1793 hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1794 p->dl.dl_runtime = p->dl.runtime = 0;
1795 p->dl.dl_deadline = p->dl.deadline = 0;
1796 p->dl.dl_period = 0;
1799 INIT_LIST_HEAD(&p->rt.run_list);
1801 #ifdef CONFIG_PREEMPT_NOTIFIERS
1802 INIT_HLIST_HEAD(&p->preempt_notifiers);
1805 #ifdef CONFIG_NUMA_BALANCING
1806 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1807 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1808 p->mm->numa_scan_seq = 0;
1811 if (clone_flags & CLONE_VM)
1812 p->numa_preferred_nid = current->numa_preferred_nid;
1814 p->numa_preferred_nid = -1;
1816 p->node_stamp = 0ULL;
1817 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1818 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1819 p->numa_work.next = &p->numa_work;
1820 p->numa_faults_memory = NULL;
1821 p->numa_faults_buffer_memory = NULL;
1822 p->last_task_numa_placement = 0;
1823 p->last_sum_exec_runtime = 0;
1825 INIT_LIST_HEAD(&p->numa_entry);
1826 p->numa_group = NULL;
1827 #endif /* CONFIG_NUMA_BALANCING */
1830 #ifdef CONFIG_NUMA_BALANCING
1831 #ifdef CONFIG_SCHED_DEBUG
1832 void set_numabalancing_state(bool enabled)
1835 sched_feat_set("NUMA");
1837 sched_feat_set("NO_NUMA");
1840 __read_mostly bool numabalancing_enabled;
1842 void set_numabalancing_state(bool enabled)
1844 numabalancing_enabled = enabled;
1846 #endif /* CONFIG_SCHED_DEBUG */
1848 #ifdef CONFIG_PROC_SYSCTL
1849 int sysctl_numa_balancing(struct ctl_table *table, int write,
1850 void __user *buffer, size_t *lenp, loff_t *ppos)
1854 int state = numabalancing_enabled;
1856 if (write && !capable(CAP_SYS_ADMIN))
1861 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
1865 set_numabalancing_state(state);
1872 * fork()/clone()-time setup:
1874 int sched_fork(unsigned long clone_flags, struct task_struct *p)
1876 unsigned long flags;
1877 int cpu = get_cpu();
1879 __sched_fork(clone_flags, p);
1881 * We mark the process as running here. This guarantees that
1882 * nobody will actually run it, and a signal or other external
1883 * event cannot wake it up and insert it on the runqueue either.
1885 p->state = TASK_RUNNING;
1888 * Make sure we do not leak PI boosting priority to the child.
1890 p->prio = current->normal_prio;
1893 * Revert to default priority/policy on fork if requested.
1895 if (unlikely(p->sched_reset_on_fork)) {
1896 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
1897 p->policy = SCHED_NORMAL;
1898 p->static_prio = NICE_TO_PRIO(0);
1900 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1901 p->static_prio = NICE_TO_PRIO(0);
1903 p->prio = p->normal_prio = __normal_prio(p);
1907 * We don't need the reset flag anymore after the fork. It has
1908 * fulfilled its duty:
1910 p->sched_reset_on_fork = 0;
1913 if (dl_prio(p->prio)) {
1916 } else if (rt_prio(p->prio)) {
1917 p->sched_class = &rt_sched_class;
1919 p->sched_class = &fair_sched_class;
1922 if (p->sched_class->task_fork)
1923 p->sched_class->task_fork(p);
1926 * The child is not yet in the pid-hash so no cgroup attach races,
1927 * and the cgroup is pinned to this child due to cgroup_fork()
1928 * is ran before sched_fork().
1930 * Silence PROVE_RCU.
1932 raw_spin_lock_irqsave(&p->pi_lock, flags);
1933 set_task_cpu(p, cpu);
1934 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1936 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1937 if (likely(sched_info_on()))
1938 memset(&p->sched_info, 0, sizeof(p->sched_info));
1940 #if defined(CONFIG_SMP)
1943 init_task_preempt_count(p);
1945 plist_node_init(&p->pushable_tasks, MAX_PRIO);
1946 RB_CLEAR_NODE(&p->pushable_dl_tasks);
1953 unsigned long to_ratio(u64 period, u64 runtime)
1955 if (runtime == RUNTIME_INF)
1959 * Doing this here saves a lot of checks in all
1960 * the calling paths, and returning zero seems
1961 * safe for them anyway.
1966 return div64_u64(runtime << 20, period);
1970 inline struct dl_bw *dl_bw_of(int i)
1972 return &cpu_rq(i)->rd->dl_bw;
1975 static inline int dl_bw_cpus(int i)
1977 struct root_domain *rd = cpu_rq(i)->rd;
1980 for_each_cpu_and(i, rd->span, cpu_active_mask)
1986 inline struct dl_bw *dl_bw_of(int i)
1988 return &cpu_rq(i)->dl.dl_bw;
1991 static inline int dl_bw_cpus(int i)
1998 void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw)
2000 dl_b->total_bw -= tsk_bw;
2004 void __dl_add(struct dl_bw *dl_b, u64 tsk_bw)
2006 dl_b->total_bw += tsk_bw;
2010 bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
2012 return dl_b->bw != -1 &&
2013 dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
2017 * We must be sure that accepting a new task (or allowing changing the
2018 * parameters of an existing one) is consistent with the bandwidth
2019 * constraints. If yes, this function also accordingly updates the currently
2020 * allocated bandwidth to reflect the new situation.
2022 * This function is called while holding p's rq->lock.
2024 static int dl_overflow(struct task_struct *p, int policy,
2025 const struct sched_attr *attr)
2028 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2029 u64 period = attr->sched_period ?: attr->sched_deadline;
2030 u64 runtime = attr->sched_runtime;
2031 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2034 if (new_bw == p->dl.dl_bw)
2038 * Either if a task, enters, leave, or stays -deadline but changes
2039 * its parameters, we may need to update accordingly the total
2040 * allocated bandwidth of the container.
2042 raw_spin_lock(&dl_b->lock);
2043 cpus = dl_bw_cpus(task_cpu(p));
2044 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2045 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2046 __dl_add(dl_b, new_bw);
2048 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2049 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2050 __dl_clear(dl_b, p->dl.dl_bw);
2051 __dl_add(dl_b, new_bw);
2053 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2054 __dl_clear(dl_b, p->dl.dl_bw);
2057 raw_spin_unlock(&dl_b->lock);
2062 extern void init_dl_bw(struct dl_bw *dl_b);
2065 * wake_up_new_task - wake up a newly created task for the first time.
2067 * This function will do some initial scheduler statistics housekeeping
2068 * that must be done for every newly created context, then puts the task
2069 * on the runqueue and wakes it.
2071 void wake_up_new_task(struct task_struct *p)
2073 unsigned long flags;
2076 raw_spin_lock_irqsave(&p->pi_lock, flags);
2079 * Fork balancing, do it here and not earlier because:
2080 * - cpus_allowed can change in the fork path
2081 * - any previously selected cpu might disappear through hotplug
2083 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2086 /* Initialize new task's runnable average */
2087 init_task_runnable_average(p);
2088 rq = __task_rq_lock(p);
2089 activate_task(rq, p, 0);
2091 trace_sched_wakeup_new(p, true);
2092 check_preempt_curr(rq, p, WF_FORK);
2094 if (p->sched_class->task_woken)
2095 p->sched_class->task_woken(rq, p);
2097 task_rq_unlock(rq, p, &flags);
2100 #ifdef CONFIG_PREEMPT_NOTIFIERS
2103 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2104 * @notifier: notifier struct to register
2106 void preempt_notifier_register(struct preempt_notifier *notifier)
2108 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2110 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2113 * preempt_notifier_unregister - no longer interested in preemption notifications
2114 * @notifier: notifier struct to unregister
2116 * This is safe to call from within a preemption notifier.
2118 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2120 hlist_del(¬ifier->link);
2122 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2124 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2126 struct preempt_notifier *notifier;
2128 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2129 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2133 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2134 struct task_struct *next)
2136 struct preempt_notifier *notifier;
2138 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2139 notifier->ops->sched_out(notifier, next);
2142 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2144 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2149 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2150 struct task_struct *next)
2154 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2157 * prepare_task_switch - prepare to switch tasks
2158 * @rq: the runqueue preparing to switch
2159 * @prev: the current task that is being switched out
2160 * @next: the task we are going to switch to.
2162 * This is called with the rq lock held and interrupts off. It must
2163 * be paired with a subsequent finish_task_switch after the context
2166 * prepare_task_switch sets up locking and calls architecture specific
2170 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2171 struct task_struct *next)
2173 trace_sched_switch(prev, next);
2174 sched_info_switch(rq, prev, next);
2175 perf_event_task_sched_out(prev, next);
2176 fire_sched_out_preempt_notifiers(prev, next);
2177 prepare_lock_switch(rq, next);
2178 prepare_arch_switch(next);
2182 * finish_task_switch - clean up after a task-switch
2183 * @rq: runqueue associated with task-switch
2184 * @prev: the thread we just switched away from.
2186 * finish_task_switch must be called after the context switch, paired
2187 * with a prepare_task_switch call before the context switch.
2188 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2189 * and do any other architecture-specific cleanup actions.
2191 * Note that we may have delayed dropping an mm in context_switch(). If
2192 * so, we finish that here outside of the runqueue lock. (Doing it
2193 * with the lock held can cause deadlocks; see schedule() for
2196 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2197 __releases(rq->lock)
2199 struct mm_struct *mm = rq->prev_mm;
2205 * A task struct has one reference for the use as "current".
2206 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2207 * schedule one last time. The schedule call will never return, and
2208 * the scheduled task must drop that reference.
2209 * The test for TASK_DEAD must occur while the runqueue locks are
2210 * still held, otherwise prev could be scheduled on another cpu, die
2211 * there before we look at prev->state, and then the reference would
2213 * Manfred Spraul <manfred@colorfullife.com>
2215 prev_state = prev->state;
2216 vtime_task_switch(prev);
2217 finish_arch_switch(prev);
2218 perf_event_task_sched_in(prev, current);
2219 finish_lock_switch(rq, prev);
2220 finish_arch_post_lock_switch();
2222 fire_sched_in_preempt_notifiers(current);
2225 if (unlikely(prev_state == TASK_DEAD)) {
2226 if (prev->sched_class->task_dead)
2227 prev->sched_class->task_dead(prev);
2230 * Remove function-return probe instances associated with this
2231 * task and put them back on the free list.
2233 kprobe_flush_task(prev);
2234 put_task_struct(prev);
2237 tick_nohz_task_switch(current);
2242 /* rq->lock is NOT held, but preemption is disabled */
2243 static inline void post_schedule(struct rq *rq)
2245 if (rq->post_schedule) {
2246 unsigned long flags;
2248 raw_spin_lock_irqsave(&rq->lock, flags);
2249 if (rq->curr->sched_class->post_schedule)
2250 rq->curr->sched_class->post_schedule(rq);
2251 raw_spin_unlock_irqrestore(&rq->lock, flags);
2253 rq->post_schedule = 0;
2259 static inline void post_schedule(struct rq *rq)
2266 * schedule_tail - first thing a freshly forked thread must call.
2267 * @prev: the thread we just switched away from.
2269 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2270 __releases(rq->lock)
2272 struct rq *rq = this_rq();
2274 finish_task_switch(rq, prev);
2277 * FIXME: do we need to worry about rq being invalidated by the
2282 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2283 /* In this case, finish_task_switch does not reenable preemption */
2286 if (current->set_child_tid)
2287 put_user(task_pid_vnr(current), current->set_child_tid);
2291 * context_switch - switch to the new MM and the new
2292 * thread's register state.
2295 context_switch(struct rq *rq, struct task_struct *prev,
2296 struct task_struct *next)
2298 struct mm_struct *mm, *oldmm;
2300 prepare_task_switch(rq, prev, next);
2303 oldmm = prev->active_mm;
2305 * For paravirt, this is coupled with an exit in switch_to to
2306 * combine the page table reload and the switch backend into
2309 arch_start_context_switch(prev);
2312 next->active_mm = oldmm;
2313 atomic_inc(&oldmm->mm_count);
2314 enter_lazy_tlb(oldmm, next);
2316 switch_mm(oldmm, mm, next);
2319 prev->active_mm = NULL;
2320 rq->prev_mm = oldmm;
2323 * Since the runqueue lock will be released by the next
2324 * task (which is an invalid locking op but in the case
2325 * of the scheduler it's an obvious special-case), so we
2326 * do an early lockdep release here:
2328 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2329 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2332 context_tracking_task_switch(prev, next);
2333 /* Here we just switch the register state and the stack. */
2334 switch_to(prev, next, prev);
2338 * this_rq must be evaluated again because prev may have moved
2339 * CPUs since it called schedule(), thus the 'rq' on its stack
2340 * frame will be invalid.
2342 finish_task_switch(this_rq(), prev);
2346 * nr_running and nr_context_switches:
2348 * externally visible scheduler statistics: current number of runnable
2349 * threads, total number of context switches performed since bootup.
2351 unsigned long nr_running(void)
2353 unsigned long i, sum = 0;
2355 for_each_online_cpu(i)
2356 sum += cpu_rq(i)->nr_running;
2361 unsigned long long nr_context_switches(void)
2364 unsigned long long sum = 0;
2366 for_each_possible_cpu(i)
2367 sum += cpu_rq(i)->nr_switches;
2372 unsigned long nr_iowait(void)
2374 unsigned long i, sum = 0;
2376 for_each_possible_cpu(i)
2377 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2382 unsigned long nr_iowait_cpu(int cpu)
2384 struct rq *this = cpu_rq(cpu);
2385 return atomic_read(&this->nr_iowait);
2391 * sched_exec - execve() is a valuable balancing opportunity, because at
2392 * this point the task has the smallest effective memory and cache footprint.
2394 void sched_exec(void)
2396 struct task_struct *p = current;
2397 unsigned long flags;
2400 raw_spin_lock_irqsave(&p->pi_lock, flags);
2401 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2402 if (dest_cpu == smp_processor_id())
2405 if (likely(cpu_active(dest_cpu))) {
2406 struct migration_arg arg = { p, dest_cpu };
2408 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2409 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2413 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2418 DEFINE_PER_CPU(struct kernel_stat, kstat);
2419 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2421 EXPORT_PER_CPU_SYMBOL(kstat);
2422 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2425 * Return any ns on the sched_clock that have not yet been accounted in
2426 * @p in case that task is currently running.
2428 * Called with task_rq_lock() held on @rq.
2430 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2434 if (task_current(rq, p)) {
2435 update_rq_clock(rq);
2436 ns = rq_clock_task(rq) - p->se.exec_start;
2444 unsigned long long task_delta_exec(struct task_struct *p)
2446 unsigned long flags;
2450 rq = task_rq_lock(p, &flags);
2451 ns = do_task_delta_exec(p, rq);
2452 task_rq_unlock(rq, p, &flags);
2458 * Return accounted runtime for the task.
2459 * In case the task is currently running, return the runtime plus current's
2460 * pending runtime that have not been accounted yet.
2462 unsigned long long task_sched_runtime(struct task_struct *p)
2464 unsigned long flags;
2468 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2470 * 64-bit doesn't need locks to atomically read a 64bit value.
2471 * So we have a optimization chance when the task's delta_exec is 0.
2472 * Reading ->on_cpu is racy, but this is ok.
2474 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2475 * If we race with it entering cpu, unaccounted time is 0. This is
2476 * indistinguishable from the read occurring a few cycles earlier.
2479 return p->se.sum_exec_runtime;
2482 rq = task_rq_lock(p, &flags);
2483 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2484 task_rq_unlock(rq, p, &flags);
2490 * This function gets called by the timer code, with HZ frequency.
2491 * We call it with interrupts disabled.
2493 void scheduler_tick(void)
2495 int cpu = smp_processor_id();
2496 struct rq *rq = cpu_rq(cpu);
2497 struct task_struct *curr = rq->curr;
2501 raw_spin_lock(&rq->lock);
2502 update_rq_clock(rq);
2503 curr->sched_class->task_tick(rq, curr, 0);
2504 update_cpu_load_active(rq);
2505 raw_spin_unlock(&rq->lock);
2507 perf_event_task_tick();
2510 rq->idle_balance = idle_cpu(cpu);
2511 trigger_load_balance(rq);
2513 rq_last_tick_reset(rq);
2516 #ifdef CONFIG_NO_HZ_FULL
2518 * scheduler_tick_max_deferment
2520 * Keep at least one tick per second when a single
2521 * active task is running because the scheduler doesn't
2522 * yet completely support full dynticks environment.
2524 * This makes sure that uptime, CFS vruntime, load
2525 * balancing, etc... continue to move forward, even
2526 * with a very low granularity.
2528 * Return: Maximum deferment in nanoseconds.
2530 u64 scheduler_tick_max_deferment(void)
2532 struct rq *rq = this_rq();
2533 unsigned long next, now = ACCESS_ONCE(jiffies);
2535 next = rq->last_sched_tick + HZ;
2537 if (time_before_eq(next, now))
2540 return jiffies_to_nsecs(next - now);
2544 notrace unsigned long get_parent_ip(unsigned long addr)
2546 if (in_lock_functions(addr)) {
2547 addr = CALLER_ADDR2;
2548 if (in_lock_functions(addr))
2549 addr = CALLER_ADDR3;
2554 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2555 defined(CONFIG_PREEMPT_TRACER))
2557 void __kprobes preempt_count_add(int val)
2559 #ifdef CONFIG_DEBUG_PREEMPT
2563 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2566 __preempt_count_add(val);
2567 #ifdef CONFIG_DEBUG_PREEMPT
2569 * Spinlock count overflowing soon?
2571 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2574 if (preempt_count() == val) {
2575 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2576 #ifdef CONFIG_DEBUG_PREEMPT
2577 current->preempt_disable_ip = ip;
2579 trace_preempt_off(CALLER_ADDR0, ip);
2582 EXPORT_SYMBOL(preempt_count_add);
2584 void __kprobes preempt_count_sub(int val)
2586 #ifdef CONFIG_DEBUG_PREEMPT
2590 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2593 * Is the spinlock portion underflowing?
2595 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2596 !(preempt_count() & PREEMPT_MASK)))
2600 if (preempt_count() == val)
2601 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2602 __preempt_count_sub(val);
2604 EXPORT_SYMBOL(preempt_count_sub);
2609 * Print scheduling while atomic bug:
2611 static noinline void __schedule_bug(struct task_struct *prev)
2613 if (oops_in_progress)
2616 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2617 prev->comm, prev->pid, preempt_count());
2619 debug_show_held_locks(prev);
2621 if (irqs_disabled())
2622 print_irqtrace_events(prev);
2623 #ifdef CONFIG_DEBUG_PREEMPT
2624 if (in_atomic_preempt_off()) {
2625 pr_err("Preemption disabled at:");
2626 print_ip_sym(current->preempt_disable_ip);
2631 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2635 * Various schedule()-time debugging checks and statistics:
2637 static inline void schedule_debug(struct task_struct *prev)
2640 * Test if we are atomic. Since do_exit() needs to call into
2641 * schedule() atomically, we ignore that path. Otherwise whine
2642 * if we are scheduling when we should not.
2644 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
2645 __schedule_bug(prev);
2648 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2650 schedstat_inc(this_rq(), sched_count);
2654 * Pick up the highest-prio task:
2656 static inline struct task_struct *
2657 pick_next_task(struct rq *rq, struct task_struct *prev)
2659 const struct sched_class *class = &fair_sched_class;
2660 struct task_struct *p;
2663 * Optimization: we know that if all tasks are in
2664 * the fair class we can call that function directly:
2666 if (likely(prev->sched_class == class &&
2667 rq->nr_running == rq->cfs.h_nr_running)) {
2668 p = fair_sched_class.pick_next_task(rq, prev);
2669 if (unlikely(p == RETRY_TASK))
2672 /* assumes fair_sched_class->next == idle_sched_class */
2674 p = idle_sched_class.pick_next_task(rq, prev);
2680 for_each_class(class) {
2681 p = class->pick_next_task(rq, prev);
2683 if (unlikely(p == RETRY_TASK))
2689 BUG(); /* the idle class will always have a runnable task */
2693 * __schedule() is the main scheduler function.
2695 * The main means of driving the scheduler and thus entering this function are:
2697 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2699 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2700 * paths. For example, see arch/x86/entry_64.S.
2702 * To drive preemption between tasks, the scheduler sets the flag in timer
2703 * interrupt handler scheduler_tick().
2705 * 3. Wakeups don't really cause entry into schedule(). They add a
2706 * task to the run-queue and that's it.
2708 * Now, if the new task added to the run-queue preempts the current
2709 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2710 * called on the nearest possible occasion:
2712 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2714 * - in syscall or exception context, at the next outmost
2715 * preempt_enable(). (this might be as soon as the wake_up()'s
2718 * - in IRQ context, return from interrupt-handler to
2719 * preemptible context
2721 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2724 * - cond_resched() call
2725 * - explicit schedule() call
2726 * - return from syscall or exception to user-space
2727 * - return from interrupt-handler to user-space
2729 static void __sched __schedule(void)
2731 struct task_struct *prev, *next;
2732 unsigned long *switch_count;
2738 cpu = smp_processor_id();
2740 rcu_note_context_switch(cpu);
2743 schedule_debug(prev);
2745 if (sched_feat(HRTICK))
2749 * Make sure that signal_pending_state()->signal_pending() below
2750 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2751 * done by the caller to avoid the race with signal_wake_up().
2753 smp_mb__before_spinlock();
2754 raw_spin_lock_irq(&rq->lock);
2756 switch_count = &prev->nivcsw;
2757 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2758 if (unlikely(signal_pending_state(prev->state, prev))) {
2759 prev->state = TASK_RUNNING;
2761 deactivate_task(rq, prev, DEQUEUE_SLEEP);
2765 * If a worker went to sleep, notify and ask workqueue
2766 * whether it wants to wake up a task to maintain
2769 if (prev->flags & PF_WQ_WORKER) {
2770 struct task_struct *to_wakeup;
2772 to_wakeup = wq_worker_sleeping(prev, cpu);
2774 try_to_wake_up_local(to_wakeup);
2777 switch_count = &prev->nvcsw;
2780 if (prev->on_rq || rq->skip_clock_update < 0)
2781 update_rq_clock(rq);
2783 next = pick_next_task(rq, prev);
2784 clear_tsk_need_resched(prev);
2785 clear_preempt_need_resched();
2786 rq->skip_clock_update = 0;
2788 if (likely(prev != next)) {
2793 context_switch(rq, prev, next); /* unlocks the rq */
2795 * The context switch have flipped the stack from under us
2796 * and restored the local variables which were saved when
2797 * this task called schedule() in the past. prev == current
2798 * is still correct, but it can be moved to another cpu/rq.
2800 cpu = smp_processor_id();
2803 raw_spin_unlock_irq(&rq->lock);
2807 sched_preempt_enable_no_resched();
2812 static inline void sched_submit_work(struct task_struct *tsk)
2814 if (!tsk->state || tsk_is_pi_blocked(tsk))
2817 * If we are going to sleep and we have plugged IO queued,
2818 * make sure to submit it to avoid deadlocks.
2820 if (blk_needs_flush_plug(tsk))
2821 blk_schedule_flush_plug(tsk);
2824 asmlinkage __visible void __sched schedule(void)
2826 struct task_struct *tsk = current;
2828 sched_submit_work(tsk);
2831 EXPORT_SYMBOL(schedule);
2833 #ifdef CONFIG_CONTEXT_TRACKING
2834 asmlinkage __visible void __sched schedule_user(void)
2837 * If we come here after a random call to set_need_resched(),
2838 * or we have been woken up remotely but the IPI has not yet arrived,
2839 * we haven't yet exited the RCU idle mode. Do it here manually until
2840 * we find a better solution.
2849 * schedule_preempt_disabled - called with preemption disabled
2851 * Returns with preemption disabled. Note: preempt_count must be 1
2853 void __sched schedule_preempt_disabled(void)
2855 sched_preempt_enable_no_resched();
2860 #ifdef CONFIG_PREEMPT
2862 * this is the entry point to schedule() from in-kernel preemption
2863 * off of preempt_enable. Kernel preemptions off return from interrupt
2864 * occur there and call schedule directly.
2866 asmlinkage __visible void __sched notrace preempt_schedule(void)
2869 * If there is a non-zero preempt_count or interrupts are disabled,
2870 * we do not want to preempt the current task. Just return..
2872 if (likely(!preemptible()))
2876 __preempt_count_add(PREEMPT_ACTIVE);
2878 __preempt_count_sub(PREEMPT_ACTIVE);
2881 * Check again in case we missed a preemption opportunity
2882 * between schedule and now.
2885 } while (need_resched());
2887 EXPORT_SYMBOL(preempt_schedule);
2888 #endif /* CONFIG_PREEMPT */
2891 * this is the entry point to schedule() from kernel preemption
2892 * off of irq context.
2893 * Note, that this is called and return with irqs disabled. This will
2894 * protect us against recursive calling from irq.
2896 asmlinkage __visible void __sched preempt_schedule_irq(void)
2898 enum ctx_state prev_state;
2900 /* Catch callers which need to be fixed */
2901 BUG_ON(preempt_count() || !irqs_disabled());
2903 prev_state = exception_enter();
2906 __preempt_count_add(PREEMPT_ACTIVE);
2909 local_irq_disable();
2910 __preempt_count_sub(PREEMPT_ACTIVE);
2913 * Check again in case we missed a preemption opportunity
2914 * between schedule and now.
2917 } while (need_resched());
2919 exception_exit(prev_state);
2922 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2925 return try_to_wake_up(curr->private, mode, wake_flags);
2927 EXPORT_SYMBOL(default_wake_function);
2929 #ifdef CONFIG_RT_MUTEXES
2932 * rt_mutex_setprio - set the current priority of a task
2934 * @prio: prio value (kernel-internal form)
2936 * This function changes the 'effective' priority of a task. It does
2937 * not touch ->normal_prio like __setscheduler().
2939 * Used by the rt_mutex code to implement priority inheritance
2940 * logic. Call site only calls if the priority of the task changed.
2942 void rt_mutex_setprio(struct task_struct *p, int prio)
2944 int oldprio, on_rq, running, enqueue_flag = 0;
2946 const struct sched_class *prev_class;
2948 BUG_ON(prio > MAX_PRIO);
2950 rq = __task_rq_lock(p);
2953 * Idle task boosting is a nono in general. There is one
2954 * exception, when PREEMPT_RT and NOHZ is active:
2956 * The idle task calls get_next_timer_interrupt() and holds
2957 * the timer wheel base->lock on the CPU and another CPU wants
2958 * to access the timer (probably to cancel it). We can safely
2959 * ignore the boosting request, as the idle CPU runs this code
2960 * with interrupts disabled and will complete the lock
2961 * protected section without being interrupted. So there is no
2962 * real need to boost.
2964 if (unlikely(p == rq->idle)) {
2965 WARN_ON(p != rq->curr);
2966 WARN_ON(p->pi_blocked_on);
2970 trace_sched_pi_setprio(p, prio);
2971 p->pi_top_task = rt_mutex_get_top_task(p);
2973 prev_class = p->sched_class;
2975 running = task_current(rq, p);
2977 dequeue_task(rq, p, 0);
2979 p->sched_class->put_prev_task(rq, p);
2982 * Boosting condition are:
2983 * 1. -rt task is running and holds mutex A
2984 * --> -dl task blocks on mutex A
2986 * 2. -dl task is running and holds mutex A
2987 * --> -dl task blocks on mutex A and could preempt the
2990 if (dl_prio(prio)) {
2991 if (!dl_prio(p->normal_prio) || (p->pi_top_task &&
2992 dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) {
2993 p->dl.dl_boosted = 1;
2994 p->dl.dl_throttled = 0;
2995 enqueue_flag = ENQUEUE_REPLENISH;
2997 p->dl.dl_boosted = 0;
2998 p->sched_class = &dl_sched_class;
2999 } else if (rt_prio(prio)) {
3000 if (dl_prio(oldprio))
3001 p->dl.dl_boosted = 0;
3003 enqueue_flag = ENQUEUE_HEAD;
3004 p->sched_class = &rt_sched_class;
3006 if (dl_prio(oldprio))
3007 p->dl.dl_boosted = 0;
3008 p->sched_class = &fair_sched_class;
3014 p->sched_class->set_curr_task(rq);
3016 enqueue_task(rq, p, enqueue_flag);
3018 check_class_changed(rq, p, prev_class, oldprio);
3020 __task_rq_unlock(rq);
3024 void set_user_nice(struct task_struct *p, long nice)
3026 int old_prio, delta, on_rq;
3027 unsigned long flags;
3030 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3033 * We have to be careful, if called from sys_setpriority(),
3034 * the task might be in the middle of scheduling on another CPU.
3036 rq = task_rq_lock(p, &flags);
3038 * The RT priorities are set via sched_setscheduler(), but we still
3039 * allow the 'normal' nice value to be set - but as expected
3040 * it wont have any effect on scheduling until the task is
3041 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3043 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3044 p->static_prio = NICE_TO_PRIO(nice);
3049 dequeue_task(rq, p, 0);
3051 p->static_prio = NICE_TO_PRIO(nice);
3054 p->prio = effective_prio(p);
3055 delta = p->prio - old_prio;
3058 enqueue_task(rq, p, 0);
3060 * If the task increased its priority or is running and
3061 * lowered its priority, then reschedule its CPU:
3063 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3064 resched_task(rq->curr);
3067 task_rq_unlock(rq, p, &flags);
3069 EXPORT_SYMBOL(set_user_nice);
3072 * can_nice - check if a task can reduce its nice value
3076 int can_nice(const struct task_struct *p, const int nice)
3078 /* convert nice value [19,-20] to rlimit style value [1,40] */
3079 int nice_rlim = nice_to_rlimit(nice);
3081 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3082 capable(CAP_SYS_NICE));
3085 #ifdef __ARCH_WANT_SYS_NICE
3088 * sys_nice - change the priority of the current process.
3089 * @increment: priority increment
3091 * sys_setpriority is a more generic, but much slower function that
3092 * does similar things.
3094 SYSCALL_DEFINE1(nice, int, increment)
3099 * Setpriority might change our priority at the same moment.
3100 * We don't have to worry. Conceptually one call occurs first
3101 * and we have a single winner.
3103 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3104 nice = task_nice(current) + increment;
3106 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3107 if (increment < 0 && !can_nice(current, nice))
3110 retval = security_task_setnice(current, nice);
3114 set_user_nice(current, nice);
3121 * task_prio - return the priority value of a given task.
3122 * @p: the task in question.
3124 * Return: The priority value as seen by users in /proc.
3125 * RT tasks are offset by -200. Normal tasks are centered
3126 * around 0, value goes from -16 to +15.
3128 int task_prio(const struct task_struct *p)
3130 return p->prio - MAX_RT_PRIO;
3134 * idle_cpu - is a given cpu idle currently?
3135 * @cpu: the processor in question.
3137 * Return: 1 if the CPU is currently idle. 0 otherwise.
3139 int idle_cpu(int cpu)
3141 struct rq *rq = cpu_rq(cpu);
3143 if (rq->curr != rq->idle)
3150 if (!llist_empty(&rq->wake_list))
3158 * idle_task - return the idle task for a given cpu.
3159 * @cpu: the processor in question.
3161 * Return: The idle task for the cpu @cpu.
3163 struct task_struct *idle_task(int cpu)
3165 return cpu_rq(cpu)->idle;
3169 * find_process_by_pid - find a process with a matching PID value.
3170 * @pid: the pid in question.
3172 * The task of @pid, if found. %NULL otherwise.
3174 static struct task_struct *find_process_by_pid(pid_t pid)
3176 return pid ? find_task_by_vpid(pid) : current;
3180 * This function initializes the sched_dl_entity of a newly becoming
3181 * SCHED_DEADLINE task.
3183 * Only the static values are considered here, the actual runtime and the
3184 * absolute deadline will be properly calculated when the task is enqueued
3185 * for the first time with its new policy.
3188 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3190 struct sched_dl_entity *dl_se = &p->dl;
3192 init_dl_task_timer(dl_se);
3193 dl_se->dl_runtime = attr->sched_runtime;
3194 dl_se->dl_deadline = attr->sched_deadline;
3195 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3196 dl_se->flags = attr->sched_flags;
3197 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3198 dl_se->dl_throttled = 0;
3200 dl_se->dl_yielded = 0;
3203 static void __setscheduler_params(struct task_struct *p,
3204 const struct sched_attr *attr)
3206 int policy = attr->sched_policy;
3208 if (policy == -1) /* setparam */
3213 if (dl_policy(policy))
3214 __setparam_dl(p, attr);
3215 else if (fair_policy(policy))
3216 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3219 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3220 * !rt_policy. Always setting this ensures that things like
3221 * getparam()/getattr() don't report silly values for !rt tasks.
3223 p->rt_priority = attr->sched_priority;
3224 p->normal_prio = normal_prio(p);
3228 /* Actually do priority change: must hold pi & rq lock. */
3229 static void __setscheduler(struct rq *rq, struct task_struct *p,
3230 const struct sched_attr *attr)
3232 __setscheduler_params(p, attr);
3235 * If we get here, there was no pi waiters boosting the
3236 * task. It is safe to use the normal prio.
3238 p->prio = normal_prio(p);
3240 if (dl_prio(p->prio))
3241 p->sched_class = &dl_sched_class;
3242 else if (rt_prio(p->prio))
3243 p->sched_class = &rt_sched_class;
3245 p->sched_class = &fair_sched_class;
3249 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3251 struct sched_dl_entity *dl_se = &p->dl;
3253 attr->sched_priority = p->rt_priority;
3254 attr->sched_runtime = dl_se->dl_runtime;
3255 attr->sched_deadline = dl_se->dl_deadline;
3256 attr->sched_period = dl_se->dl_period;
3257 attr->sched_flags = dl_se->flags;
3261 * This function validates the new parameters of a -deadline task.
3262 * We ask for the deadline not being zero, and greater or equal
3263 * than the runtime, as well as the period of being zero or
3264 * greater than deadline. Furthermore, we have to be sure that
3265 * user parameters are above the internal resolution of 1us (we
3266 * check sched_runtime only since it is always the smaller one) and
3267 * below 2^63 ns (we have to check both sched_deadline and
3268 * sched_period, as the latter can be zero).
3271 __checkparam_dl(const struct sched_attr *attr)
3274 if (attr->sched_deadline == 0)
3278 * Since we truncate DL_SCALE bits, make sure we're at least
3281 if (attr->sched_runtime < (1ULL << DL_SCALE))
3285 * Since we use the MSB for wrap-around and sign issues, make
3286 * sure it's not set (mind that period can be equal to zero).
3288 if (attr->sched_deadline & (1ULL << 63) ||
3289 attr->sched_period & (1ULL << 63))
3292 /* runtime <= deadline <= period (if period != 0) */
3293 if ((attr->sched_period != 0 &&
3294 attr->sched_period < attr->sched_deadline) ||
3295 attr->sched_deadline < attr->sched_runtime)
3302 * check the target process has a UID that matches the current process's
3304 static bool check_same_owner(struct task_struct *p)
3306 const struct cred *cred = current_cred(), *pcred;
3310 pcred = __task_cred(p);
3311 match = (uid_eq(cred->euid, pcred->euid) ||
3312 uid_eq(cred->euid, pcred->uid));
3317 static int __sched_setscheduler(struct task_struct *p,
3318 const struct sched_attr *attr,
3321 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3322 MAX_RT_PRIO - 1 - attr->sched_priority;
3323 int retval, oldprio, oldpolicy = -1, on_rq, running;
3324 int policy = attr->sched_policy;
3325 unsigned long flags;
3326 const struct sched_class *prev_class;
3330 /* may grab non-irq protected spin_locks */
3331 BUG_ON(in_interrupt());
3333 /* double check policy once rq lock held */
3335 reset_on_fork = p->sched_reset_on_fork;
3336 policy = oldpolicy = p->policy;
3338 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3340 if (policy != SCHED_DEADLINE &&
3341 policy != SCHED_FIFO && policy != SCHED_RR &&
3342 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3343 policy != SCHED_IDLE)
3347 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3351 * Valid priorities for SCHED_FIFO and SCHED_RR are
3352 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3353 * SCHED_BATCH and SCHED_IDLE is 0.
3355 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3356 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3358 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3359 (rt_policy(policy) != (attr->sched_priority != 0)))
3363 * Allow unprivileged RT tasks to decrease priority:
3365 if (user && !capable(CAP_SYS_NICE)) {
3366 if (fair_policy(policy)) {
3367 if (attr->sched_nice < task_nice(p) &&
3368 !can_nice(p, attr->sched_nice))
3372 if (rt_policy(policy)) {
3373 unsigned long rlim_rtprio =
3374 task_rlimit(p, RLIMIT_RTPRIO);
3376 /* can't set/change the rt policy */
3377 if (policy != p->policy && !rlim_rtprio)
3380 /* can't increase priority */
3381 if (attr->sched_priority > p->rt_priority &&
3382 attr->sched_priority > rlim_rtprio)
3387 * Can't set/change SCHED_DEADLINE policy at all for now
3388 * (safest behavior); in the future we would like to allow
3389 * unprivileged DL tasks to increase their relative deadline
3390 * or reduce their runtime (both ways reducing utilization)
3392 if (dl_policy(policy))
3396 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3397 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3399 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3400 if (!can_nice(p, task_nice(p)))
3404 /* can't change other user's priorities */
3405 if (!check_same_owner(p))
3408 /* Normal users shall not reset the sched_reset_on_fork flag */
3409 if (p->sched_reset_on_fork && !reset_on_fork)
3414 retval = security_task_setscheduler(p);
3420 * make sure no PI-waiters arrive (or leave) while we are
3421 * changing the priority of the task:
3423 * To be able to change p->policy safely, the appropriate
3424 * runqueue lock must be held.
3426 rq = task_rq_lock(p, &flags);
3429 * Changing the policy of the stop threads its a very bad idea
3431 if (p == rq->stop) {
3432 task_rq_unlock(rq, p, &flags);
3437 * If not changing anything there's no need to proceed further,
3438 * but store a possible modification of reset_on_fork.
3440 if (unlikely(policy == p->policy)) {
3441 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3443 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3445 if (dl_policy(policy))
3448 p->sched_reset_on_fork = reset_on_fork;
3449 task_rq_unlock(rq, p, &flags);
3455 #ifdef CONFIG_RT_GROUP_SCHED
3457 * Do not allow realtime tasks into groups that have no runtime
3460 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3461 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3462 !task_group_is_autogroup(task_group(p))) {
3463 task_rq_unlock(rq, p, &flags);
3468 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3469 cpumask_t *span = rq->rd->span;
3472 * Don't allow tasks with an affinity mask smaller than
3473 * the entire root_domain to become SCHED_DEADLINE. We
3474 * will also fail if there's no bandwidth available.
3476 if (!cpumask_subset(span, &p->cpus_allowed) ||
3477 rq->rd->dl_bw.bw == 0) {
3478 task_rq_unlock(rq, p, &flags);
3485 /* recheck policy now with rq lock held */
3486 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3487 policy = oldpolicy = -1;
3488 task_rq_unlock(rq, p, &flags);
3493 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3494 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3497 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3498 task_rq_unlock(rq, p, &flags);
3502 p->sched_reset_on_fork = reset_on_fork;
3506 * Special case for priority boosted tasks.
3508 * If the new priority is lower or equal (user space view)
3509 * than the current (boosted) priority, we just store the new
3510 * normal parameters and do not touch the scheduler class and
3511 * the runqueue. This will be done when the task deboost
3514 if (rt_mutex_check_prio(p, newprio)) {
3515 __setscheduler_params(p, attr);
3516 task_rq_unlock(rq, p, &flags);
3521 running = task_current(rq, p);
3523 dequeue_task(rq, p, 0);
3525 p->sched_class->put_prev_task(rq, p);
3527 prev_class = p->sched_class;
3528 __setscheduler(rq, p, attr);
3531 p->sched_class->set_curr_task(rq);
3534 * We enqueue to tail when the priority of a task is
3535 * increased (user space view).
3537 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
3540 check_class_changed(rq, p, prev_class, oldprio);
3541 task_rq_unlock(rq, p, &flags);
3543 rt_mutex_adjust_pi(p);
3548 static int _sched_setscheduler(struct task_struct *p, int policy,
3549 const struct sched_param *param, bool check)
3551 struct sched_attr attr = {
3552 .sched_policy = policy,
3553 .sched_priority = param->sched_priority,
3554 .sched_nice = PRIO_TO_NICE(p->static_prio),
3558 * Fixup the legacy SCHED_RESET_ON_FORK hack
3560 if (policy & SCHED_RESET_ON_FORK) {
3561 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3562 policy &= ~SCHED_RESET_ON_FORK;
3563 attr.sched_policy = policy;
3566 return __sched_setscheduler(p, &attr, check);
3569 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3570 * @p: the task in question.
3571 * @policy: new policy.
3572 * @param: structure containing the new RT priority.
3574 * Return: 0 on success. An error code otherwise.
3576 * NOTE that the task may be already dead.
3578 int sched_setscheduler(struct task_struct *p, int policy,
3579 const struct sched_param *param)
3581 return _sched_setscheduler(p, policy, param, true);
3583 EXPORT_SYMBOL_GPL(sched_setscheduler);
3585 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
3587 return __sched_setscheduler(p, attr, true);
3589 EXPORT_SYMBOL_GPL(sched_setattr);
3592 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3593 * @p: the task in question.
3594 * @policy: new policy.
3595 * @param: structure containing the new RT priority.
3597 * Just like sched_setscheduler, only don't bother checking if the
3598 * current context has permission. For example, this is needed in
3599 * stop_machine(): we create temporary high priority worker threads,
3600 * but our caller might not have that capability.
3602 * Return: 0 on success. An error code otherwise.
3604 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3605 const struct sched_param *param)
3607 return _sched_setscheduler(p, policy, param, false);
3611 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3613 struct sched_param lparam;
3614 struct task_struct *p;
3617 if (!param || pid < 0)
3619 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3624 p = find_process_by_pid(pid);
3626 retval = sched_setscheduler(p, policy, &lparam);
3633 * Mimics kernel/events/core.c perf_copy_attr().
3635 static int sched_copy_attr(struct sched_attr __user *uattr,
3636 struct sched_attr *attr)
3641 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
3645 * zero the full structure, so that a short copy will be nice.
3647 memset(attr, 0, sizeof(*attr));
3649 ret = get_user(size, &uattr->size);
3653 if (size > PAGE_SIZE) /* silly large */
3656 if (!size) /* abi compat */
3657 size = SCHED_ATTR_SIZE_VER0;
3659 if (size < SCHED_ATTR_SIZE_VER0)
3663 * If we're handed a bigger struct than we know of,
3664 * ensure all the unknown bits are 0 - i.e. new
3665 * user-space does not rely on any kernel feature
3666 * extensions we dont know about yet.
3668 if (size > sizeof(*attr)) {
3669 unsigned char __user *addr;
3670 unsigned char __user *end;
3673 addr = (void __user *)uattr + sizeof(*attr);
3674 end = (void __user *)uattr + size;
3676 for (; addr < end; addr++) {
3677 ret = get_user(val, addr);
3683 size = sizeof(*attr);
3686 ret = copy_from_user(attr, uattr, size);
3691 * XXX: do we want to be lenient like existing syscalls; or do we want
3692 * to be strict and return an error on out-of-bounds values?
3694 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
3699 put_user(sizeof(*attr), &uattr->size);
3704 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3705 * @pid: the pid in question.
3706 * @policy: new policy.
3707 * @param: structure containing the new RT priority.
3709 * Return: 0 on success. An error code otherwise.
3711 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3712 struct sched_param __user *, param)
3714 /* negative values for policy are not valid */
3718 return do_sched_setscheduler(pid, policy, param);
3722 * sys_sched_setparam - set/change the RT priority of a thread
3723 * @pid: the pid in question.
3724 * @param: structure containing the new RT priority.
3726 * Return: 0 on success. An error code otherwise.
3728 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3730 return do_sched_setscheduler(pid, -1, param);
3734 * sys_sched_setattr - same as above, but with extended sched_attr
3735 * @pid: the pid in question.
3736 * @uattr: structure containing the extended parameters.
3737 * @flags: for future extension.
3739 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
3740 unsigned int, flags)
3742 struct sched_attr attr;
3743 struct task_struct *p;
3746 if (!uattr || pid < 0 || flags)
3749 retval = sched_copy_attr(uattr, &attr);
3753 if (attr.sched_policy < 0)
3758 p = find_process_by_pid(pid);
3760 retval = sched_setattr(p, &attr);
3767 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3768 * @pid: the pid in question.
3770 * Return: On success, the policy of the thread. Otherwise, a negative error
3773 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3775 struct task_struct *p;
3783 p = find_process_by_pid(pid);
3785 retval = security_task_getscheduler(p);
3788 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3795 * sys_sched_getparam - get the RT priority of a thread
3796 * @pid: the pid in question.
3797 * @param: structure containing the RT priority.
3799 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3802 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3804 struct sched_param lp = { .sched_priority = 0 };
3805 struct task_struct *p;
3808 if (!param || pid < 0)
3812 p = find_process_by_pid(pid);
3817 retval = security_task_getscheduler(p);
3821 if (task_has_rt_policy(p))
3822 lp.sched_priority = p->rt_priority;
3826 * This one might sleep, we cannot do it with a spinlock held ...
3828 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3837 static int sched_read_attr(struct sched_attr __user *uattr,
3838 struct sched_attr *attr,
3843 if (!access_ok(VERIFY_WRITE, uattr, usize))
3847 * If we're handed a smaller struct than we know of,
3848 * ensure all the unknown bits are 0 - i.e. old
3849 * user-space does not get uncomplete information.
3851 if (usize < sizeof(*attr)) {
3852 unsigned char *addr;
3855 addr = (void *)attr + usize;
3856 end = (void *)attr + sizeof(*attr);
3858 for (; addr < end; addr++) {
3866 ret = copy_to_user(uattr, attr, attr->size);
3874 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3875 * @pid: the pid in question.
3876 * @uattr: structure containing the extended parameters.
3877 * @size: sizeof(attr) for fwd/bwd comp.
3878 * @flags: for future extension.
3880 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
3881 unsigned int, size, unsigned int, flags)
3883 struct sched_attr attr = {
3884 .size = sizeof(struct sched_attr),
3886 struct task_struct *p;
3889 if (!uattr || pid < 0 || size > PAGE_SIZE ||
3890 size < SCHED_ATTR_SIZE_VER0 || flags)
3894 p = find_process_by_pid(pid);
3899 retval = security_task_getscheduler(p);
3903 attr.sched_policy = p->policy;
3904 if (p->sched_reset_on_fork)
3905 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3906 if (task_has_dl_policy(p))
3907 __getparam_dl(p, &attr);
3908 else if (task_has_rt_policy(p))
3909 attr.sched_priority = p->rt_priority;
3911 attr.sched_nice = task_nice(p);
3915 retval = sched_read_attr(uattr, &attr, size);
3923 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3925 cpumask_var_t cpus_allowed, new_mask;
3926 struct task_struct *p;
3931 p = find_process_by_pid(pid);
3937 /* Prevent p going away */
3941 if (p->flags & PF_NO_SETAFFINITY) {
3945 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
3949 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
3951 goto out_free_cpus_allowed;
3954 if (!check_same_owner(p)) {
3956 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
3963 retval = security_task_setscheduler(p);
3968 cpuset_cpus_allowed(p, cpus_allowed);
3969 cpumask_and(new_mask, in_mask, cpus_allowed);
3972 * Since bandwidth control happens on root_domain basis,
3973 * if admission test is enabled, we only admit -deadline
3974 * tasks allowed to run on all the CPUs in the task's
3978 if (task_has_dl_policy(p)) {
3979 const struct cpumask *span = task_rq(p)->rd->span;
3981 if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {
3988 retval = set_cpus_allowed_ptr(p, new_mask);
3991 cpuset_cpus_allowed(p, cpus_allowed);
3992 if (!cpumask_subset(new_mask, cpus_allowed)) {
3994 * We must have raced with a concurrent cpuset
3995 * update. Just reset the cpus_allowed to the
3996 * cpuset's cpus_allowed
3998 cpumask_copy(new_mask, cpus_allowed);
4003 free_cpumask_var(new_mask);
4004 out_free_cpus_allowed:
4005 free_cpumask_var(cpus_allowed);
4011 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4012 struct cpumask *new_mask)
4014 if (len < cpumask_size())
4015 cpumask_clear(new_mask);
4016 else if (len > cpumask_size())
4017 len = cpumask_size();
4019 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4023 * sys_sched_setaffinity - set the cpu affinity of a process
4024 * @pid: pid of the process
4025 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4026 * @user_mask_ptr: user-space pointer to the new cpu mask
4028 * Return: 0 on success. An error code otherwise.
4030 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4031 unsigned long __user *, user_mask_ptr)
4033 cpumask_var_t new_mask;
4036 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4039 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4041 retval = sched_setaffinity(pid, new_mask);
4042 free_cpumask_var(new_mask);
4046 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4048 struct task_struct *p;
4049 unsigned long flags;
4055 p = find_process_by_pid(pid);
4059 retval = security_task_getscheduler(p);
4063 raw_spin_lock_irqsave(&p->pi_lock, flags);
4064 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4065 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4074 * sys_sched_getaffinity - get the cpu affinity of a process
4075 * @pid: pid of the process
4076 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4077 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4079 * Return: 0 on success. An error code otherwise.
4081 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4082 unsigned long __user *, user_mask_ptr)
4087 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4089 if (len & (sizeof(unsigned long)-1))
4092 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4095 ret = sched_getaffinity(pid, mask);
4097 size_t retlen = min_t(size_t, len, cpumask_size());
4099 if (copy_to_user(user_mask_ptr, mask, retlen))
4104 free_cpumask_var(mask);
4110 * sys_sched_yield - yield the current processor to other threads.
4112 * This function yields the current CPU to other tasks. If there are no
4113 * other threads running on this CPU then this function will return.
4117 SYSCALL_DEFINE0(sched_yield)
4119 struct rq *rq = this_rq_lock();
4121 schedstat_inc(rq, yld_count);
4122 current->sched_class->yield_task(rq);
4125 * Since we are going to call schedule() anyway, there's
4126 * no need to preempt or enable interrupts:
4128 __release(rq->lock);
4129 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4130 do_raw_spin_unlock(&rq->lock);
4131 sched_preempt_enable_no_resched();
4138 static void __cond_resched(void)
4140 __preempt_count_add(PREEMPT_ACTIVE);
4142 __preempt_count_sub(PREEMPT_ACTIVE);
4145 int __sched _cond_resched(void)
4147 if (should_resched()) {
4153 EXPORT_SYMBOL(_cond_resched);
4156 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4157 * call schedule, and on return reacquire the lock.
4159 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4160 * operations here to prevent schedule() from being called twice (once via
4161 * spin_unlock(), once by hand).
4163 int __cond_resched_lock(spinlock_t *lock)
4165 int resched = should_resched();
4168 lockdep_assert_held(lock);
4170 if (spin_needbreak(lock) || resched) {
4181 EXPORT_SYMBOL(__cond_resched_lock);
4183 int __sched __cond_resched_softirq(void)
4185 BUG_ON(!in_softirq());
4187 if (should_resched()) {
4195 EXPORT_SYMBOL(__cond_resched_softirq);
4198 * yield - yield the current processor to other threads.
4200 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4202 * The scheduler is at all times free to pick the calling task as the most
4203 * eligible task to run, if removing the yield() call from your code breaks
4204 * it, its already broken.
4206 * Typical broken usage is:
4211 * where one assumes that yield() will let 'the other' process run that will
4212 * make event true. If the current task is a SCHED_FIFO task that will never
4213 * happen. Never use yield() as a progress guarantee!!
4215 * If you want to use yield() to wait for something, use wait_event().
4216 * If you want to use yield() to be 'nice' for others, use cond_resched().
4217 * If you still want to use yield(), do not!
4219 void __sched yield(void)
4221 set_current_state(TASK_RUNNING);
4224 EXPORT_SYMBOL(yield);
4227 * yield_to - yield the current processor to another thread in
4228 * your thread group, or accelerate that thread toward the
4229 * processor it's on.
4231 * @preempt: whether task preemption is allowed or not
4233 * It's the caller's job to ensure that the target task struct
4234 * can't go away on us before we can do any checks.
4237 * true (>0) if we indeed boosted the target task.
4238 * false (0) if we failed to boost the target.
4239 * -ESRCH if there's no task to yield to.
4241 int __sched yield_to(struct task_struct *p, bool preempt)
4243 struct task_struct *curr = current;
4244 struct rq *rq, *p_rq;
4245 unsigned long flags;
4248 local_irq_save(flags);
4254 * If we're the only runnable task on the rq and target rq also
4255 * has only one task, there's absolutely no point in yielding.
4257 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4262 double_rq_lock(rq, p_rq);
4263 if (task_rq(p) != p_rq) {
4264 double_rq_unlock(rq, p_rq);
4268 if (!curr->sched_class->yield_to_task)
4271 if (curr->sched_class != p->sched_class)
4274 if (task_running(p_rq, p) || p->state)
4277 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4279 schedstat_inc(rq, yld_count);
4281 * Make p's CPU reschedule; pick_next_entity takes care of
4284 if (preempt && rq != p_rq)
4285 resched_task(p_rq->curr);
4289 double_rq_unlock(rq, p_rq);
4291 local_irq_restore(flags);
4298 EXPORT_SYMBOL_GPL(yield_to);
4301 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4302 * that process accounting knows that this is a task in IO wait state.
4304 void __sched io_schedule(void)
4306 struct rq *rq = raw_rq();
4308 delayacct_blkio_start();
4309 atomic_inc(&rq->nr_iowait);
4310 blk_flush_plug(current);
4311 current->in_iowait = 1;
4313 current->in_iowait = 0;
4314 atomic_dec(&rq->nr_iowait);
4315 delayacct_blkio_end();
4317 EXPORT_SYMBOL(io_schedule);
4319 long __sched io_schedule_timeout(long timeout)
4321 struct rq *rq = raw_rq();
4324 delayacct_blkio_start();
4325 atomic_inc(&rq->nr_iowait);
4326 blk_flush_plug(current);
4327 current->in_iowait = 1;
4328 ret = schedule_timeout(timeout);
4329 current->in_iowait = 0;
4330 atomic_dec(&rq->nr_iowait);
4331 delayacct_blkio_end();
4336 * sys_sched_get_priority_max - return maximum RT priority.
4337 * @policy: scheduling class.
4339 * Return: On success, this syscall returns the maximum
4340 * rt_priority that can be used by a given scheduling class.
4341 * On failure, a negative error code is returned.
4343 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4350 ret = MAX_USER_RT_PRIO-1;
4352 case SCHED_DEADLINE:
4363 * sys_sched_get_priority_min - return minimum RT priority.
4364 * @policy: scheduling class.
4366 * Return: On success, this syscall returns the minimum
4367 * rt_priority that can be used by a given scheduling class.
4368 * On failure, a negative error code is returned.
4370 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4379 case SCHED_DEADLINE:
4389 * sys_sched_rr_get_interval - return the default timeslice of a process.
4390 * @pid: pid of the process.
4391 * @interval: userspace pointer to the timeslice value.
4393 * this syscall writes the default timeslice value of a given process
4394 * into the user-space timespec buffer. A value of '0' means infinity.
4396 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4399 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4400 struct timespec __user *, interval)
4402 struct task_struct *p;
4403 unsigned int time_slice;
4404 unsigned long flags;
4414 p = find_process_by_pid(pid);
4418 retval = security_task_getscheduler(p);
4422 rq = task_rq_lock(p, &flags);
4424 if (p->sched_class->get_rr_interval)
4425 time_slice = p->sched_class->get_rr_interval(rq, p);
4426 task_rq_unlock(rq, p, &flags);
4429 jiffies_to_timespec(time_slice, &t);
4430 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4438 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4440 void sched_show_task(struct task_struct *p)
4442 unsigned long free = 0;
4446 state = p->state ? __ffs(p->state) + 1 : 0;
4447 printk(KERN_INFO "%-15.15s %c", p->comm,
4448 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4449 #if BITS_PER_LONG == 32
4450 if (state == TASK_RUNNING)
4451 printk(KERN_CONT " running ");
4453 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4455 if (state == TASK_RUNNING)
4456 printk(KERN_CONT " running task ");
4458 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4460 #ifdef CONFIG_DEBUG_STACK_USAGE
4461 free = stack_not_used(p);
4464 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4466 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4467 task_pid_nr(p), ppid,
4468 (unsigned long)task_thread_info(p)->flags);
4470 print_worker_info(KERN_INFO, p);
4471 show_stack(p, NULL);
4474 void show_state_filter(unsigned long state_filter)
4476 struct task_struct *g, *p;
4478 #if BITS_PER_LONG == 32
4480 " task PC stack pid father\n");
4483 " task PC stack pid father\n");
4486 do_each_thread(g, p) {
4488 * reset the NMI-timeout, listing all files on a slow
4489 * console might take a lot of time:
4491 touch_nmi_watchdog();
4492 if (!state_filter || (p->state & state_filter))
4494 } while_each_thread(g, p);
4496 touch_all_softlockup_watchdogs();
4498 #ifdef CONFIG_SCHED_DEBUG
4499 sysrq_sched_debug_show();
4503 * Only show locks if all tasks are dumped:
4506 debug_show_all_locks();
4509 void init_idle_bootup_task(struct task_struct *idle)
4511 idle->sched_class = &idle_sched_class;
4515 * init_idle - set up an idle thread for a given CPU
4516 * @idle: task in question
4517 * @cpu: cpu the idle task belongs to
4519 * NOTE: this function does not set the idle thread's NEED_RESCHED
4520 * flag, to make booting more robust.
4522 void init_idle(struct task_struct *idle, int cpu)
4524 struct rq *rq = cpu_rq(cpu);
4525 unsigned long flags;
4527 raw_spin_lock_irqsave(&rq->lock, flags);
4529 __sched_fork(0, idle);
4530 idle->state = TASK_RUNNING;
4531 idle->se.exec_start = sched_clock();
4533 do_set_cpus_allowed(idle, cpumask_of(cpu));
4535 * We're having a chicken and egg problem, even though we are
4536 * holding rq->lock, the cpu isn't yet set to this cpu so the
4537 * lockdep check in task_group() will fail.
4539 * Similar case to sched_fork(). / Alternatively we could
4540 * use task_rq_lock() here and obtain the other rq->lock.
4545 __set_task_cpu(idle, cpu);
4548 rq->curr = rq->idle = idle;
4550 #if defined(CONFIG_SMP)
4553 raw_spin_unlock_irqrestore(&rq->lock, flags);
4555 /* Set the preempt count _outside_ the spinlocks! */
4556 init_idle_preempt_count(idle, cpu);
4559 * The idle tasks have their own, simple scheduling class:
4561 idle->sched_class = &idle_sched_class;
4562 ftrace_graph_init_idle_task(idle, cpu);
4563 vtime_init_idle(idle, cpu);
4564 #if defined(CONFIG_SMP)
4565 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4570 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4572 if (p->sched_class && p->sched_class->set_cpus_allowed)
4573 p->sched_class->set_cpus_allowed(p, new_mask);
4575 cpumask_copy(&p->cpus_allowed, new_mask);
4576 p->nr_cpus_allowed = cpumask_weight(new_mask);
4580 * This is how migration works:
4582 * 1) we invoke migration_cpu_stop() on the target CPU using
4584 * 2) stopper starts to run (implicitly forcing the migrated thread
4586 * 3) it checks whether the migrated task is still in the wrong runqueue.
4587 * 4) if it's in the wrong runqueue then the migration thread removes
4588 * it and puts it into the right queue.
4589 * 5) stopper completes and stop_one_cpu() returns and the migration
4594 * Change a given task's CPU affinity. Migrate the thread to a
4595 * proper CPU and schedule it away if the CPU it's executing on
4596 * is removed from the allowed bitmask.
4598 * NOTE: the caller must have a valid reference to the task, the
4599 * task must not exit() & deallocate itself prematurely. The
4600 * call is not atomic; no spinlocks may be held.
4602 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4604 unsigned long flags;
4606 unsigned int dest_cpu;
4609 rq = task_rq_lock(p, &flags);
4611 if (cpumask_equal(&p->cpus_allowed, new_mask))
4614 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4619 do_set_cpus_allowed(p, new_mask);
4621 /* Can the task run on the task's current CPU? If so, we're done */
4622 if (cpumask_test_cpu(task_cpu(p), new_mask))
4625 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4627 struct migration_arg arg = { p, dest_cpu };
4628 /* Need help from migration thread: drop lock and wait. */
4629 task_rq_unlock(rq, p, &flags);
4630 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4631 tlb_migrate_finish(p->mm);
4635 task_rq_unlock(rq, p, &flags);
4639 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4642 * Move (not current) task off this cpu, onto dest cpu. We're doing
4643 * this because either it can't run here any more (set_cpus_allowed()
4644 * away from this CPU, or CPU going down), or because we're
4645 * attempting to rebalance this task on exec (sched_exec).
4647 * So we race with normal scheduler movements, but that's OK, as long
4648 * as the task is no longer on this CPU.
4650 * Returns non-zero if task was successfully migrated.
4652 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4654 struct rq *rq_dest, *rq_src;
4657 if (unlikely(!cpu_active(dest_cpu)))
4660 rq_src = cpu_rq(src_cpu);
4661 rq_dest = cpu_rq(dest_cpu);
4663 raw_spin_lock(&p->pi_lock);
4664 double_rq_lock(rq_src, rq_dest);
4665 /* Already moved. */
4666 if (task_cpu(p) != src_cpu)
4668 /* Affinity changed (again). */
4669 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4673 * If we're not on a rq, the next wake-up will ensure we're
4677 dequeue_task(rq_src, p, 0);
4678 set_task_cpu(p, dest_cpu);
4679 enqueue_task(rq_dest, p, 0);
4680 check_preempt_curr(rq_dest, p, 0);
4685 double_rq_unlock(rq_src, rq_dest);
4686 raw_spin_unlock(&p->pi_lock);
4690 #ifdef CONFIG_NUMA_BALANCING
4691 /* Migrate current task p to target_cpu */
4692 int migrate_task_to(struct task_struct *p, int target_cpu)
4694 struct migration_arg arg = { p, target_cpu };
4695 int curr_cpu = task_cpu(p);
4697 if (curr_cpu == target_cpu)
4700 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4703 /* TODO: This is not properly updating schedstats */
4705 trace_sched_move_numa(p, curr_cpu, target_cpu);
4706 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4710 * Requeue a task on a given node and accurately track the number of NUMA
4711 * tasks on the runqueues
4713 void sched_setnuma(struct task_struct *p, int nid)
4716 unsigned long flags;
4717 bool on_rq, running;
4719 rq = task_rq_lock(p, &flags);
4721 running = task_current(rq, p);
4724 dequeue_task(rq, p, 0);
4726 p->sched_class->put_prev_task(rq, p);
4728 p->numa_preferred_nid = nid;
4731 p->sched_class->set_curr_task(rq);
4733 enqueue_task(rq, p, 0);
4734 task_rq_unlock(rq, p, &flags);
4739 * migration_cpu_stop - this will be executed by a highprio stopper thread
4740 * and performs thread migration by bumping thread off CPU then
4741 * 'pushing' onto another runqueue.
4743 static int migration_cpu_stop(void *data)
4745 struct migration_arg *arg = data;
4748 * The original target cpu might have gone down and we might
4749 * be on another cpu but it doesn't matter.
4751 local_irq_disable();
4752 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4757 #ifdef CONFIG_HOTPLUG_CPU
4760 * Ensures that the idle task is using init_mm right before its cpu goes
4763 void idle_task_exit(void)
4765 struct mm_struct *mm = current->active_mm;
4767 BUG_ON(cpu_online(smp_processor_id()));
4769 if (mm != &init_mm) {
4770 switch_mm(mm, &init_mm, current);
4771 finish_arch_post_lock_switch();
4777 * Since this CPU is going 'away' for a while, fold any nr_active delta
4778 * we might have. Assumes we're called after migrate_tasks() so that the
4779 * nr_active count is stable.
4781 * Also see the comment "Global load-average calculations".
4783 static void calc_load_migrate(struct rq *rq)
4785 long delta = calc_load_fold_active(rq);
4787 atomic_long_add(delta, &calc_load_tasks);
4790 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
4794 static const struct sched_class fake_sched_class = {
4795 .put_prev_task = put_prev_task_fake,
4798 static struct task_struct fake_task = {
4800 * Avoid pull_{rt,dl}_task()
4802 .prio = MAX_PRIO + 1,
4803 .sched_class = &fake_sched_class,
4807 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4808 * try_to_wake_up()->select_task_rq().
4810 * Called with rq->lock held even though we'er in stop_machine() and
4811 * there's no concurrency possible, we hold the required locks anyway
4812 * because of lock validation efforts.
4814 static void migrate_tasks(unsigned int dead_cpu)
4816 struct rq *rq = cpu_rq(dead_cpu);
4817 struct task_struct *next, *stop = rq->stop;
4821 * Fudge the rq selection such that the below task selection loop
4822 * doesn't get stuck on the currently eligible stop task.
4824 * We're currently inside stop_machine() and the rq is either stuck
4825 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4826 * either way we should never end up calling schedule() until we're
4832 * put_prev_task() and pick_next_task() sched
4833 * class method both need to have an up-to-date
4834 * value of rq->clock[_task]
4836 update_rq_clock(rq);
4840 * There's this thread running, bail when that's the only
4843 if (rq->nr_running == 1)
4846 next = pick_next_task(rq, &fake_task);
4848 next->sched_class->put_prev_task(rq, next);
4850 /* Find suitable destination for @next, with force if needed. */
4851 dest_cpu = select_fallback_rq(dead_cpu, next);
4852 raw_spin_unlock(&rq->lock);
4854 __migrate_task(next, dead_cpu, dest_cpu);
4856 raw_spin_lock(&rq->lock);
4862 #endif /* CONFIG_HOTPLUG_CPU */
4864 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4866 static struct ctl_table sd_ctl_dir[] = {
4868 .procname = "sched_domain",
4874 static struct ctl_table sd_ctl_root[] = {
4876 .procname = "kernel",
4878 .child = sd_ctl_dir,
4883 static struct ctl_table *sd_alloc_ctl_entry(int n)
4885 struct ctl_table *entry =
4886 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4891 static void sd_free_ctl_entry(struct ctl_table **tablep)
4893 struct ctl_table *entry;
4896 * In the intermediate directories, both the child directory and
4897 * procname are dynamically allocated and could fail but the mode
4898 * will always be set. In the lowest directory the names are
4899 * static strings and all have proc handlers.
4901 for (entry = *tablep; entry->mode; entry++) {
4903 sd_free_ctl_entry(&entry->child);
4904 if (entry->proc_handler == NULL)
4905 kfree(entry->procname);
4912 static int min_load_idx = 0;
4913 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
4916 set_table_entry(struct ctl_table *entry,
4917 const char *procname, void *data, int maxlen,
4918 umode_t mode, proc_handler *proc_handler,
4921 entry->procname = procname;
4923 entry->maxlen = maxlen;
4925 entry->proc_handler = proc_handler;
4928 entry->extra1 = &min_load_idx;
4929 entry->extra2 = &max_load_idx;
4933 static struct ctl_table *
4934 sd_alloc_ctl_domain_table(struct sched_domain *sd)
4936 struct ctl_table *table = sd_alloc_ctl_entry(14);
4941 set_table_entry(&table[0], "min_interval", &sd->min_interval,
4942 sizeof(long), 0644, proc_doulongvec_minmax, false);
4943 set_table_entry(&table[1], "max_interval", &sd->max_interval,
4944 sizeof(long), 0644, proc_doulongvec_minmax, false);
4945 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4946 sizeof(int), 0644, proc_dointvec_minmax, true);
4947 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4948 sizeof(int), 0644, proc_dointvec_minmax, true);
4949 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4950 sizeof(int), 0644, proc_dointvec_minmax, true);
4951 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4952 sizeof(int), 0644, proc_dointvec_minmax, true);
4953 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4954 sizeof(int), 0644, proc_dointvec_minmax, true);
4955 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4956 sizeof(int), 0644, proc_dointvec_minmax, false);
4957 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4958 sizeof(int), 0644, proc_dointvec_minmax, false);
4959 set_table_entry(&table[9], "cache_nice_tries",
4960 &sd->cache_nice_tries,
4961 sizeof(int), 0644, proc_dointvec_minmax, false);
4962 set_table_entry(&table[10], "flags", &sd->flags,
4963 sizeof(int), 0644, proc_dointvec_minmax, false);
4964 set_table_entry(&table[11], "max_newidle_lb_cost",
4965 &sd->max_newidle_lb_cost,
4966 sizeof(long), 0644, proc_doulongvec_minmax, false);
4967 set_table_entry(&table[12], "name", sd->name,
4968 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
4969 /* &table[13] is terminator */
4974 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
4976 struct ctl_table *entry, *table;
4977 struct sched_domain *sd;
4978 int domain_num = 0, i;
4981 for_each_domain(cpu, sd)
4983 entry = table = sd_alloc_ctl_entry(domain_num + 1);
4988 for_each_domain(cpu, sd) {
4989 snprintf(buf, 32, "domain%d", i);
4990 entry->procname = kstrdup(buf, GFP_KERNEL);
4992 entry->child = sd_alloc_ctl_domain_table(sd);
4999 static struct ctl_table_header *sd_sysctl_header;
5000 static void register_sched_domain_sysctl(void)
5002 int i, cpu_num = num_possible_cpus();
5003 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5006 WARN_ON(sd_ctl_dir[0].child);
5007 sd_ctl_dir[0].child = entry;
5012 for_each_possible_cpu(i) {
5013 snprintf(buf, 32, "cpu%d", i);
5014 entry->procname = kstrdup(buf, GFP_KERNEL);
5016 entry->child = sd_alloc_ctl_cpu_table(i);
5020 WARN_ON(sd_sysctl_header);
5021 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5024 /* may be called multiple times per register */
5025 static void unregister_sched_domain_sysctl(void)
5027 if (sd_sysctl_header)
5028 unregister_sysctl_table(sd_sysctl_header);
5029 sd_sysctl_header = NULL;
5030 if (sd_ctl_dir[0].child)
5031 sd_free_ctl_entry(&sd_ctl_dir[0].child);
5034 static void register_sched_domain_sysctl(void)
5037 static void unregister_sched_domain_sysctl(void)
5042 static void set_rq_online(struct rq *rq)
5045 const struct sched_class *class;
5047 cpumask_set_cpu(rq->cpu, rq->rd->online);
5050 for_each_class(class) {
5051 if (class->rq_online)
5052 class->rq_online(rq);
5057 static void set_rq_offline(struct rq *rq)
5060 const struct sched_class *class;
5062 for_each_class(class) {
5063 if (class->rq_offline)
5064 class->rq_offline(rq);
5067 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5073 * migration_call - callback that gets triggered when a CPU is added.
5074 * Here we can start up the necessary migration thread for the new CPU.
5077 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5079 int cpu = (long)hcpu;
5080 unsigned long flags;
5081 struct rq *rq = cpu_rq(cpu);
5083 switch (action & ~CPU_TASKS_FROZEN) {
5085 case CPU_UP_PREPARE:
5086 rq->calc_load_update = calc_load_update;
5090 /* Update our root-domain */
5091 raw_spin_lock_irqsave(&rq->lock, flags);
5093 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5097 raw_spin_unlock_irqrestore(&rq->lock, flags);
5100 #ifdef CONFIG_HOTPLUG_CPU
5102 sched_ttwu_pending();
5103 /* Update our root-domain */
5104 raw_spin_lock_irqsave(&rq->lock, flags);
5106 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5110 BUG_ON(rq->nr_running != 1); /* the migration thread */
5111 raw_spin_unlock_irqrestore(&rq->lock, flags);
5115 calc_load_migrate(rq);
5120 update_max_interval();
5126 * Register at high priority so that task migration (migrate_all_tasks)
5127 * happens before everything else. This has to be lower priority than
5128 * the notifier in the perf_event subsystem, though.
5130 static struct notifier_block migration_notifier = {
5131 .notifier_call = migration_call,
5132 .priority = CPU_PRI_MIGRATION,
5135 static void __cpuinit set_cpu_rq_start_time(void)
5137 int cpu = smp_processor_id();
5138 struct rq *rq = cpu_rq(cpu);
5139 rq->age_stamp = sched_clock_cpu(cpu);
5142 static int sched_cpu_active(struct notifier_block *nfb,
5143 unsigned long action, void *hcpu)
5145 switch (action & ~CPU_TASKS_FROZEN) {
5147 set_cpu_rq_start_time();
5149 case CPU_DOWN_FAILED:
5150 set_cpu_active((long)hcpu, true);
5157 static int sched_cpu_inactive(struct notifier_block *nfb,
5158 unsigned long action, void *hcpu)
5160 unsigned long flags;
5161 long cpu = (long)hcpu;
5163 switch (action & ~CPU_TASKS_FROZEN) {
5164 case CPU_DOWN_PREPARE:
5165 set_cpu_active(cpu, false);
5167 /* explicitly allow suspend */
5168 if (!(action & CPU_TASKS_FROZEN)) {
5169 struct dl_bw *dl_b = dl_bw_of(cpu);
5173 raw_spin_lock_irqsave(&dl_b->lock, flags);
5174 cpus = dl_bw_cpus(cpu);
5175 overflow = __dl_overflow(dl_b, cpus, 0, 0);
5176 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5179 return notifier_from_errno(-EBUSY);
5187 static int __init migration_init(void)
5189 void *cpu = (void *)(long)smp_processor_id();
5192 /* Initialize migration for the boot CPU */
5193 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5194 BUG_ON(err == NOTIFY_BAD);
5195 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5196 register_cpu_notifier(&migration_notifier);
5198 /* Register cpu active notifiers */
5199 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5200 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5204 early_initcall(migration_init);
5209 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5211 #ifdef CONFIG_SCHED_DEBUG
5213 static __read_mostly int sched_debug_enabled;
5215 static int __init sched_debug_setup(char *str)
5217 sched_debug_enabled = 1;
5221 early_param("sched_debug", sched_debug_setup);
5223 static inline bool sched_debug(void)
5225 return sched_debug_enabled;
5228 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5229 struct cpumask *groupmask)
5231 struct sched_group *group = sd->groups;
5234 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5235 cpumask_clear(groupmask);
5237 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5239 if (!(sd->flags & SD_LOAD_BALANCE)) {
5240 printk("does not load-balance\n");
5242 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5247 printk(KERN_CONT "span %s level %s\n", str, sd->name);
5249 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5250 printk(KERN_ERR "ERROR: domain->span does not contain "
5253 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5254 printk(KERN_ERR "ERROR: domain->groups does not contain"
5258 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5262 printk(KERN_ERR "ERROR: group is NULL\n");
5267 * Even though we initialize ->capacity to something semi-sane,
5268 * we leave capacity_orig unset. This allows us to detect if
5269 * domain iteration is still funny without causing /0 traps.
5271 if (!group->sgc->capacity_orig) {
5272 printk(KERN_CONT "\n");
5273 printk(KERN_ERR "ERROR: domain->cpu_capacity not set\n");
5277 if (!cpumask_weight(sched_group_cpus(group))) {
5278 printk(KERN_CONT "\n");
5279 printk(KERN_ERR "ERROR: empty group\n");
5283 if (!(sd->flags & SD_OVERLAP) &&
5284 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5285 printk(KERN_CONT "\n");
5286 printk(KERN_ERR "ERROR: repeated CPUs\n");
5290 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5292 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5294 printk(KERN_CONT " %s", str);
5295 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5296 printk(KERN_CONT " (cpu_capacity = %d)",
5297 group->sgc->capacity);
5300 group = group->next;
5301 } while (group != sd->groups);
5302 printk(KERN_CONT "\n");
5304 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5305 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5308 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5309 printk(KERN_ERR "ERROR: parent span is not a superset "
5310 "of domain->span\n");
5314 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5318 if (!sched_debug_enabled)
5322 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5326 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5329 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5337 #else /* !CONFIG_SCHED_DEBUG */
5338 # define sched_domain_debug(sd, cpu) do { } while (0)
5339 static inline bool sched_debug(void)
5343 #endif /* CONFIG_SCHED_DEBUG */
5345 static int sd_degenerate(struct sched_domain *sd)
5347 if (cpumask_weight(sched_domain_span(sd)) == 1)
5350 /* Following flags need at least 2 groups */
5351 if (sd->flags & (SD_LOAD_BALANCE |
5352 SD_BALANCE_NEWIDLE |
5355 SD_SHARE_CPUCAPACITY |
5356 SD_SHARE_PKG_RESOURCES |
5357 SD_SHARE_POWERDOMAIN)) {
5358 if (sd->groups != sd->groups->next)
5362 /* Following flags don't use groups */
5363 if (sd->flags & (SD_WAKE_AFFINE))
5370 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5372 unsigned long cflags = sd->flags, pflags = parent->flags;
5374 if (sd_degenerate(parent))
5377 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5380 /* Flags needing groups don't count if only 1 group in parent */
5381 if (parent->groups == parent->groups->next) {
5382 pflags &= ~(SD_LOAD_BALANCE |
5383 SD_BALANCE_NEWIDLE |
5386 SD_SHARE_CPUCAPACITY |
5387 SD_SHARE_PKG_RESOURCES |
5389 SD_SHARE_POWERDOMAIN);
5390 if (nr_node_ids == 1)
5391 pflags &= ~SD_SERIALIZE;
5393 if (~cflags & pflags)
5399 static void free_rootdomain(struct rcu_head *rcu)
5401 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5403 cpupri_cleanup(&rd->cpupri);
5404 cpudl_cleanup(&rd->cpudl);
5405 free_cpumask_var(rd->dlo_mask);
5406 free_cpumask_var(rd->rto_mask);
5407 free_cpumask_var(rd->online);
5408 free_cpumask_var(rd->span);
5412 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5414 struct root_domain *old_rd = NULL;
5415 unsigned long flags;
5417 raw_spin_lock_irqsave(&rq->lock, flags);
5422 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5425 cpumask_clear_cpu(rq->cpu, old_rd->span);
5428 * If we dont want to free the old_rd yet then
5429 * set old_rd to NULL to skip the freeing later
5432 if (!atomic_dec_and_test(&old_rd->refcount))
5436 atomic_inc(&rd->refcount);
5439 cpumask_set_cpu(rq->cpu, rd->span);
5440 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5443 raw_spin_unlock_irqrestore(&rq->lock, flags);
5446 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5449 static int init_rootdomain(struct root_domain *rd)
5451 memset(rd, 0, sizeof(*rd));
5453 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5455 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5457 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5459 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5462 init_dl_bw(&rd->dl_bw);
5463 if (cpudl_init(&rd->cpudl) != 0)
5466 if (cpupri_init(&rd->cpupri) != 0)
5471 free_cpumask_var(rd->rto_mask);
5473 free_cpumask_var(rd->dlo_mask);
5475 free_cpumask_var(rd->online);
5477 free_cpumask_var(rd->span);
5483 * By default the system creates a single root-domain with all cpus as
5484 * members (mimicking the global state we have today).
5486 struct root_domain def_root_domain;
5488 static void init_defrootdomain(void)
5490 init_rootdomain(&def_root_domain);
5492 atomic_set(&def_root_domain.refcount, 1);
5495 static struct root_domain *alloc_rootdomain(void)
5497 struct root_domain *rd;
5499 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5503 if (init_rootdomain(rd) != 0) {
5511 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5513 struct sched_group *tmp, *first;
5522 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5527 } while (sg != first);
5530 static void free_sched_domain(struct rcu_head *rcu)
5532 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5535 * If its an overlapping domain it has private groups, iterate and
5538 if (sd->flags & SD_OVERLAP) {
5539 free_sched_groups(sd->groups, 1);
5540 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5541 kfree(sd->groups->sgc);
5547 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5549 call_rcu(&sd->rcu, free_sched_domain);
5552 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5554 for (; sd; sd = sd->parent)
5555 destroy_sched_domain(sd, cpu);
5559 * Keep a special pointer to the highest sched_domain that has
5560 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5561 * allows us to avoid some pointer chasing select_idle_sibling().
5563 * Also keep a unique ID per domain (we use the first cpu number in
5564 * the cpumask of the domain), this allows us to quickly tell if
5565 * two cpus are in the same cache domain, see cpus_share_cache().
5567 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5568 DEFINE_PER_CPU(int, sd_llc_size);
5569 DEFINE_PER_CPU(int, sd_llc_id);
5570 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5571 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5572 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5574 static void update_top_cache_domain(int cpu)
5576 struct sched_domain *sd;
5577 struct sched_domain *busy_sd = NULL;
5581 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5583 id = cpumask_first(sched_domain_span(sd));
5584 size = cpumask_weight(sched_domain_span(sd));
5585 busy_sd = sd->parent; /* sd_busy */
5587 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5589 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5590 per_cpu(sd_llc_size, cpu) = size;
5591 per_cpu(sd_llc_id, cpu) = id;
5593 sd = lowest_flag_domain(cpu, SD_NUMA);
5594 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5596 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5597 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5601 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5602 * hold the hotplug lock.
5605 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5607 struct rq *rq = cpu_rq(cpu);
5608 struct sched_domain *tmp;
5610 /* Remove the sched domains which do not contribute to scheduling. */
5611 for (tmp = sd; tmp; ) {
5612 struct sched_domain *parent = tmp->parent;
5616 if (sd_parent_degenerate(tmp, parent)) {
5617 tmp->parent = parent->parent;
5619 parent->parent->child = tmp;
5621 * Transfer SD_PREFER_SIBLING down in case of a
5622 * degenerate parent; the spans match for this
5623 * so the property transfers.
5625 if (parent->flags & SD_PREFER_SIBLING)
5626 tmp->flags |= SD_PREFER_SIBLING;
5627 destroy_sched_domain(parent, cpu);
5632 if (sd && sd_degenerate(sd)) {
5635 destroy_sched_domain(tmp, cpu);
5640 sched_domain_debug(sd, cpu);
5642 rq_attach_root(rq, rd);
5644 rcu_assign_pointer(rq->sd, sd);
5645 destroy_sched_domains(tmp, cpu);
5647 update_top_cache_domain(cpu);
5650 /* cpus with isolated domains */
5651 static cpumask_var_t cpu_isolated_map;
5653 /* Setup the mask of cpus configured for isolated domains */
5654 static int __init isolated_cpu_setup(char *str)
5656 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5657 cpulist_parse(str, cpu_isolated_map);
5661 __setup("isolcpus=", isolated_cpu_setup);
5664 struct sched_domain ** __percpu sd;
5665 struct root_domain *rd;
5676 * Build an iteration mask that can exclude certain CPUs from the upwards
5679 * Asymmetric node setups can result in situations where the domain tree is of
5680 * unequal depth, make sure to skip domains that already cover the entire
5683 * In that case build_sched_domains() will have terminated the iteration early
5684 * and our sibling sd spans will be empty. Domains should always include the
5685 * cpu they're built on, so check that.
5688 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5690 const struct cpumask *span = sched_domain_span(sd);
5691 struct sd_data *sdd = sd->private;
5692 struct sched_domain *sibling;
5695 for_each_cpu(i, span) {
5696 sibling = *per_cpu_ptr(sdd->sd, i);
5697 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5700 cpumask_set_cpu(i, sched_group_mask(sg));
5705 * Return the canonical balance cpu for this group, this is the first cpu
5706 * of this group that's also in the iteration mask.
5708 int group_balance_cpu(struct sched_group *sg)
5710 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5714 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5716 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5717 const struct cpumask *span = sched_domain_span(sd);
5718 struct cpumask *covered = sched_domains_tmpmask;
5719 struct sd_data *sdd = sd->private;
5720 struct sched_domain *child;
5723 cpumask_clear(covered);
5725 for_each_cpu(i, span) {
5726 struct cpumask *sg_span;
5728 if (cpumask_test_cpu(i, covered))
5731 child = *per_cpu_ptr(sdd->sd, i);
5733 /* See the comment near build_group_mask(). */
5734 if (!cpumask_test_cpu(i, sched_domain_span(child)))
5737 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5738 GFP_KERNEL, cpu_to_node(cpu));
5743 sg_span = sched_group_cpus(sg);
5745 child = child->child;
5746 cpumask_copy(sg_span, sched_domain_span(child));
5748 cpumask_set_cpu(i, sg_span);
5750 cpumask_or(covered, covered, sg_span);
5752 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
5753 if (atomic_inc_return(&sg->sgc->ref) == 1)
5754 build_group_mask(sd, sg);
5757 * Initialize sgc->capacity such that even if we mess up the
5758 * domains and no possible iteration will get us here, we won't
5761 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
5762 sg->sgc->capacity_orig = sg->sgc->capacity;
5765 * Make sure the first group of this domain contains the
5766 * canonical balance cpu. Otherwise the sched_domain iteration
5767 * breaks. See update_sg_lb_stats().
5769 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5770 group_balance_cpu(sg) == cpu)
5780 sd->groups = groups;
5785 free_sched_groups(first, 0);
5790 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5792 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5793 struct sched_domain *child = sd->child;
5796 cpu = cpumask_first(sched_domain_span(child));
5799 *sg = *per_cpu_ptr(sdd->sg, cpu);
5800 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
5801 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
5808 * build_sched_groups will build a circular linked list of the groups
5809 * covered by the given span, and will set each group's ->cpumask correctly,
5810 * and ->cpu_capacity to 0.
5812 * Assumes the sched_domain tree is fully constructed
5815 build_sched_groups(struct sched_domain *sd, int cpu)
5817 struct sched_group *first = NULL, *last = NULL;
5818 struct sd_data *sdd = sd->private;
5819 const struct cpumask *span = sched_domain_span(sd);
5820 struct cpumask *covered;
5823 get_group(cpu, sdd, &sd->groups);
5824 atomic_inc(&sd->groups->ref);
5826 if (cpu != cpumask_first(span))
5829 lockdep_assert_held(&sched_domains_mutex);
5830 covered = sched_domains_tmpmask;
5832 cpumask_clear(covered);
5834 for_each_cpu(i, span) {
5835 struct sched_group *sg;
5838 if (cpumask_test_cpu(i, covered))
5841 group = get_group(i, sdd, &sg);
5842 cpumask_setall(sched_group_mask(sg));
5844 for_each_cpu(j, span) {
5845 if (get_group(j, sdd, NULL) != group)
5848 cpumask_set_cpu(j, covered);
5849 cpumask_set_cpu(j, sched_group_cpus(sg));
5864 * Initialize sched groups cpu_capacity.
5866 * cpu_capacity indicates the capacity of sched group, which is used while
5867 * distributing the load between different sched groups in a sched domain.
5868 * Typically cpu_capacity for all the groups in a sched domain will be same
5869 * unless there are asymmetries in the topology. If there are asymmetries,
5870 * group having more cpu_capacity will pickup more load compared to the
5871 * group having less cpu_capacity.
5873 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
5875 struct sched_group *sg = sd->groups;
5880 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5882 } while (sg != sd->groups);
5884 if (cpu != group_balance_cpu(sg))
5887 update_group_capacity(sd, cpu);
5888 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
5892 * Initializers for schedule domains
5893 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5896 static int default_relax_domain_level = -1;
5897 int sched_domain_level_max;
5899 static int __init setup_relax_domain_level(char *str)
5901 if (kstrtoint(str, 0, &default_relax_domain_level))
5902 pr_warn("Unable to set relax_domain_level\n");
5906 __setup("relax_domain_level=", setup_relax_domain_level);
5908 static void set_domain_attribute(struct sched_domain *sd,
5909 struct sched_domain_attr *attr)
5913 if (!attr || attr->relax_domain_level < 0) {
5914 if (default_relax_domain_level < 0)
5917 request = default_relax_domain_level;
5919 request = attr->relax_domain_level;
5920 if (request < sd->level) {
5921 /* turn off idle balance on this domain */
5922 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5924 /* turn on idle balance on this domain */
5925 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5929 static void __sdt_free(const struct cpumask *cpu_map);
5930 static int __sdt_alloc(const struct cpumask *cpu_map);
5932 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5933 const struct cpumask *cpu_map)
5937 if (!atomic_read(&d->rd->refcount))
5938 free_rootdomain(&d->rd->rcu); /* fall through */
5940 free_percpu(d->sd); /* fall through */
5942 __sdt_free(cpu_map); /* fall through */
5948 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5949 const struct cpumask *cpu_map)
5951 memset(d, 0, sizeof(*d));
5953 if (__sdt_alloc(cpu_map))
5954 return sa_sd_storage;
5955 d->sd = alloc_percpu(struct sched_domain *);
5957 return sa_sd_storage;
5958 d->rd = alloc_rootdomain();
5961 return sa_rootdomain;
5965 * NULL the sd_data elements we've used to build the sched_domain and
5966 * sched_group structure so that the subsequent __free_domain_allocs()
5967 * will not free the data we're using.
5969 static void claim_allocations(int cpu, struct sched_domain *sd)
5971 struct sd_data *sdd = sd->private;
5973 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
5974 *per_cpu_ptr(sdd->sd, cpu) = NULL;
5976 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
5977 *per_cpu_ptr(sdd->sg, cpu) = NULL;
5979 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
5980 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
5984 static int sched_domains_numa_levels;
5985 static int *sched_domains_numa_distance;
5986 static struct cpumask ***sched_domains_numa_masks;
5987 static int sched_domains_curr_level;
5991 * SD_flags allowed in topology descriptions.
5993 * SD_SHARE_CPUCAPACITY - describes SMT topologies
5994 * SD_SHARE_PKG_RESOURCES - describes shared caches
5995 * SD_NUMA - describes NUMA topologies
5996 * SD_SHARE_POWERDOMAIN - describes shared power domain
5999 * SD_ASYM_PACKING - describes SMT quirks
6001 #define TOPOLOGY_SD_FLAGS \
6002 (SD_SHARE_CPUCAPACITY | \
6003 SD_SHARE_PKG_RESOURCES | \
6006 SD_SHARE_POWERDOMAIN)
6008 static struct sched_domain *
6009 sd_init(struct sched_domain_topology_level *tl, int cpu)
6011 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6012 int sd_weight, sd_flags = 0;
6016 * Ugly hack to pass state to sd_numa_mask()...
6018 sched_domains_curr_level = tl->numa_level;
6021 sd_weight = cpumask_weight(tl->mask(cpu));
6024 sd_flags = (*tl->sd_flags)();
6025 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6026 "wrong sd_flags in topology description\n"))
6027 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6029 *sd = (struct sched_domain){
6030 .min_interval = sd_weight,
6031 .max_interval = 2*sd_weight,
6033 .imbalance_pct = 125,
6035 .cache_nice_tries = 0,
6042 .flags = 1*SD_LOAD_BALANCE
6043 | 1*SD_BALANCE_NEWIDLE
6048 | 0*SD_SHARE_CPUCAPACITY
6049 | 0*SD_SHARE_PKG_RESOURCES
6051 | 0*SD_PREFER_SIBLING
6056 .last_balance = jiffies,
6057 .balance_interval = sd_weight,
6059 .max_newidle_lb_cost = 0,
6060 .next_decay_max_lb_cost = jiffies,
6061 #ifdef CONFIG_SCHED_DEBUG
6067 * Convert topological properties into behaviour.
6070 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6071 sd->imbalance_pct = 110;
6072 sd->smt_gain = 1178; /* ~15% */
6074 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6075 sd->imbalance_pct = 117;
6076 sd->cache_nice_tries = 1;
6080 } else if (sd->flags & SD_NUMA) {
6081 sd->cache_nice_tries = 2;
6085 sd->flags |= SD_SERIALIZE;
6086 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6087 sd->flags &= ~(SD_BALANCE_EXEC |
6094 sd->flags |= SD_PREFER_SIBLING;
6095 sd->cache_nice_tries = 1;
6100 sd->private = &tl->data;
6106 * Topology list, bottom-up.
6108 static struct sched_domain_topology_level default_topology[] = {
6109 #ifdef CONFIG_SCHED_SMT
6110 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6112 #ifdef CONFIG_SCHED_MC
6113 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6115 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6119 struct sched_domain_topology_level *sched_domain_topology = default_topology;
6121 #define for_each_sd_topology(tl) \
6122 for (tl = sched_domain_topology; tl->mask; tl++)
6124 void set_sched_topology(struct sched_domain_topology_level *tl)
6126 sched_domain_topology = tl;
6131 static const struct cpumask *sd_numa_mask(int cpu)
6133 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6136 static void sched_numa_warn(const char *str)
6138 static int done = false;
6146 printk(KERN_WARNING "ERROR: %s\n\n", str);
6148 for (i = 0; i < nr_node_ids; i++) {
6149 printk(KERN_WARNING " ");
6150 for (j = 0; j < nr_node_ids; j++)
6151 printk(KERN_CONT "%02d ", node_distance(i,j));
6152 printk(KERN_CONT "\n");
6154 printk(KERN_WARNING "\n");
6157 static bool find_numa_distance(int distance)
6161 if (distance == node_distance(0, 0))
6164 for (i = 0; i < sched_domains_numa_levels; i++) {
6165 if (sched_domains_numa_distance[i] == distance)
6172 static void sched_init_numa(void)
6174 int next_distance, curr_distance = node_distance(0, 0);
6175 struct sched_domain_topology_level *tl;
6179 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6180 if (!sched_domains_numa_distance)
6184 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6185 * unique distances in the node_distance() table.
6187 * Assumes node_distance(0,j) includes all distances in
6188 * node_distance(i,j) in order to avoid cubic time.
6190 next_distance = curr_distance;
6191 for (i = 0; i < nr_node_ids; i++) {
6192 for (j = 0; j < nr_node_ids; j++) {
6193 for (k = 0; k < nr_node_ids; k++) {
6194 int distance = node_distance(i, k);
6196 if (distance > curr_distance &&
6197 (distance < next_distance ||
6198 next_distance == curr_distance))
6199 next_distance = distance;
6202 * While not a strong assumption it would be nice to know
6203 * about cases where if node A is connected to B, B is not
6204 * equally connected to A.
6206 if (sched_debug() && node_distance(k, i) != distance)
6207 sched_numa_warn("Node-distance not symmetric");
6209 if (sched_debug() && i && !find_numa_distance(distance))
6210 sched_numa_warn("Node-0 not representative");
6212 if (next_distance != curr_distance) {
6213 sched_domains_numa_distance[level++] = next_distance;
6214 sched_domains_numa_levels = level;
6215 curr_distance = next_distance;
6220 * In case of sched_debug() we verify the above assumption.
6226 * 'level' contains the number of unique distances, excluding the
6227 * identity distance node_distance(i,i).
6229 * The sched_domains_numa_distance[] array includes the actual distance
6234 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6235 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6236 * the array will contain less then 'level' members. This could be
6237 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6238 * in other functions.
6240 * We reset it to 'level' at the end of this function.
6242 sched_domains_numa_levels = 0;
6244 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6245 if (!sched_domains_numa_masks)
6249 * Now for each level, construct a mask per node which contains all
6250 * cpus of nodes that are that many hops away from us.
6252 for (i = 0; i < level; i++) {
6253 sched_domains_numa_masks[i] =
6254 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6255 if (!sched_domains_numa_masks[i])
6258 for (j = 0; j < nr_node_ids; j++) {
6259 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6263 sched_domains_numa_masks[i][j] = mask;
6265 for (k = 0; k < nr_node_ids; k++) {
6266 if (node_distance(j, k) > sched_domains_numa_distance[i])
6269 cpumask_or(mask, mask, cpumask_of_node(k));
6274 /* Compute default topology size */
6275 for (i = 0; sched_domain_topology[i].mask; i++);
6277 tl = kzalloc((i + level + 1) *
6278 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6283 * Copy the default topology bits..
6285 for (i = 0; sched_domain_topology[i].mask; i++)
6286 tl[i] = sched_domain_topology[i];
6289 * .. and append 'j' levels of NUMA goodness.
6291 for (j = 0; j < level; i++, j++) {
6292 tl[i] = (struct sched_domain_topology_level){
6293 .mask = sd_numa_mask,
6294 .sd_flags = cpu_numa_flags,
6295 .flags = SDTL_OVERLAP,
6301 sched_domain_topology = tl;
6303 sched_domains_numa_levels = level;
6306 static void sched_domains_numa_masks_set(int cpu)
6309 int node = cpu_to_node(cpu);
6311 for (i = 0; i < sched_domains_numa_levels; i++) {
6312 for (j = 0; j < nr_node_ids; j++) {
6313 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6314 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6319 static void sched_domains_numa_masks_clear(int cpu)
6322 for (i = 0; i < sched_domains_numa_levels; i++) {
6323 for (j = 0; j < nr_node_ids; j++)
6324 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6329 * Update sched_domains_numa_masks[level][node] array when new cpus
6332 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6333 unsigned long action,
6336 int cpu = (long)hcpu;
6338 switch (action & ~CPU_TASKS_FROZEN) {
6340 sched_domains_numa_masks_set(cpu);
6344 sched_domains_numa_masks_clear(cpu);
6354 static inline void sched_init_numa(void)
6358 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6359 unsigned long action,
6364 #endif /* CONFIG_NUMA */
6366 static int __sdt_alloc(const struct cpumask *cpu_map)
6368 struct sched_domain_topology_level *tl;
6371 for_each_sd_topology(tl) {
6372 struct sd_data *sdd = &tl->data;
6374 sdd->sd = alloc_percpu(struct sched_domain *);
6378 sdd->sg = alloc_percpu(struct sched_group *);
6382 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6386 for_each_cpu(j, cpu_map) {
6387 struct sched_domain *sd;
6388 struct sched_group *sg;
6389 struct sched_group_capacity *sgc;
6391 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6392 GFP_KERNEL, cpu_to_node(j));
6396 *per_cpu_ptr(sdd->sd, j) = sd;
6398 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6399 GFP_KERNEL, cpu_to_node(j));
6405 *per_cpu_ptr(sdd->sg, j) = sg;
6407 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6408 GFP_KERNEL, cpu_to_node(j));
6412 *per_cpu_ptr(sdd->sgc, j) = sgc;
6419 static void __sdt_free(const struct cpumask *cpu_map)
6421 struct sched_domain_topology_level *tl;
6424 for_each_sd_topology(tl) {
6425 struct sd_data *sdd = &tl->data;
6427 for_each_cpu(j, cpu_map) {
6428 struct sched_domain *sd;
6431 sd = *per_cpu_ptr(sdd->sd, j);
6432 if (sd && (sd->flags & SD_OVERLAP))
6433 free_sched_groups(sd->groups, 0);
6434 kfree(*per_cpu_ptr(sdd->sd, j));
6438 kfree(*per_cpu_ptr(sdd->sg, j));
6440 kfree(*per_cpu_ptr(sdd->sgc, j));
6442 free_percpu(sdd->sd);
6444 free_percpu(sdd->sg);
6446 free_percpu(sdd->sgc);
6451 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6452 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6453 struct sched_domain *child, int cpu)
6455 struct sched_domain *sd = sd_init(tl, cpu);
6459 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6461 sd->level = child->level + 1;
6462 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6466 set_domain_attribute(sd, attr);
6472 * Build sched domains for a given set of cpus and attach the sched domains
6473 * to the individual cpus
6475 static int build_sched_domains(const struct cpumask *cpu_map,
6476 struct sched_domain_attr *attr)
6478 enum s_alloc alloc_state;
6479 struct sched_domain *sd;
6481 int i, ret = -ENOMEM;
6483 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6484 if (alloc_state != sa_rootdomain)
6487 /* Set up domains for cpus specified by the cpu_map. */
6488 for_each_cpu(i, cpu_map) {
6489 struct sched_domain_topology_level *tl;
6492 for_each_sd_topology(tl) {
6493 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6494 if (tl == sched_domain_topology)
6495 *per_cpu_ptr(d.sd, i) = sd;
6496 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6497 sd->flags |= SD_OVERLAP;
6498 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6503 /* Build the groups for the domains */
6504 for_each_cpu(i, cpu_map) {
6505 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6506 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6507 if (sd->flags & SD_OVERLAP) {
6508 if (build_overlap_sched_groups(sd, i))
6511 if (build_sched_groups(sd, i))
6517 /* Calculate CPU capacity for physical packages and nodes */
6518 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6519 if (!cpumask_test_cpu(i, cpu_map))
6522 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6523 claim_allocations(i, sd);
6524 init_sched_groups_capacity(i, sd);
6528 /* Attach the domains */
6530 for_each_cpu(i, cpu_map) {
6531 sd = *per_cpu_ptr(d.sd, i);
6532 cpu_attach_domain(sd, d.rd, i);
6538 __free_domain_allocs(&d, alloc_state, cpu_map);
6542 static cpumask_var_t *doms_cur; /* current sched domains */
6543 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6544 static struct sched_domain_attr *dattr_cur;
6545 /* attribues of custom domains in 'doms_cur' */
6548 * Special case: If a kmalloc of a doms_cur partition (array of
6549 * cpumask) fails, then fallback to a single sched domain,
6550 * as determined by the single cpumask fallback_doms.
6552 static cpumask_var_t fallback_doms;
6555 * arch_update_cpu_topology lets virtualized architectures update the
6556 * cpu core maps. It is supposed to return 1 if the topology changed
6557 * or 0 if it stayed the same.
6559 int __weak arch_update_cpu_topology(void)
6564 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6567 cpumask_var_t *doms;
6569 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6572 for (i = 0; i < ndoms; i++) {
6573 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6574 free_sched_domains(doms, i);
6581 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6584 for (i = 0; i < ndoms; i++)
6585 free_cpumask_var(doms[i]);
6590 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6591 * For now this just excludes isolated cpus, but could be used to
6592 * exclude other special cases in the future.
6594 static int init_sched_domains(const struct cpumask *cpu_map)
6598 arch_update_cpu_topology();
6600 doms_cur = alloc_sched_domains(ndoms_cur);
6602 doms_cur = &fallback_doms;
6603 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6604 err = build_sched_domains(doms_cur[0], NULL);
6605 register_sched_domain_sysctl();
6611 * Detach sched domains from a group of cpus specified in cpu_map
6612 * These cpus will now be attached to the NULL domain
6614 static void detach_destroy_domains(const struct cpumask *cpu_map)
6619 for_each_cpu(i, cpu_map)
6620 cpu_attach_domain(NULL, &def_root_domain, i);
6624 /* handle null as "default" */
6625 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6626 struct sched_domain_attr *new, int idx_new)
6628 struct sched_domain_attr tmp;
6635 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6636 new ? (new + idx_new) : &tmp,
6637 sizeof(struct sched_domain_attr));
6641 * Partition sched domains as specified by the 'ndoms_new'
6642 * cpumasks in the array doms_new[] of cpumasks. This compares
6643 * doms_new[] to the current sched domain partitioning, doms_cur[].
6644 * It destroys each deleted domain and builds each new domain.
6646 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6647 * The masks don't intersect (don't overlap.) We should setup one
6648 * sched domain for each mask. CPUs not in any of the cpumasks will
6649 * not be load balanced. If the same cpumask appears both in the
6650 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6653 * The passed in 'doms_new' should be allocated using
6654 * alloc_sched_domains. This routine takes ownership of it and will
6655 * free_sched_domains it when done with it. If the caller failed the
6656 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6657 * and partition_sched_domains() will fallback to the single partition
6658 * 'fallback_doms', it also forces the domains to be rebuilt.
6660 * If doms_new == NULL it will be replaced with cpu_online_mask.
6661 * ndoms_new == 0 is a special case for destroying existing domains,
6662 * and it will not create the default domain.
6664 * Call with hotplug lock held
6666 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
6667 struct sched_domain_attr *dattr_new)
6672 mutex_lock(&sched_domains_mutex);
6674 /* always unregister in case we don't destroy any domains */
6675 unregister_sched_domain_sysctl();
6677 /* Let architecture update cpu core mappings. */
6678 new_topology = arch_update_cpu_topology();
6680 n = doms_new ? ndoms_new : 0;
6682 /* Destroy deleted domains */
6683 for (i = 0; i < ndoms_cur; i++) {
6684 for (j = 0; j < n && !new_topology; j++) {
6685 if (cpumask_equal(doms_cur[i], doms_new[j])
6686 && dattrs_equal(dattr_cur, i, dattr_new, j))
6689 /* no match - a current sched domain not in new doms_new[] */
6690 detach_destroy_domains(doms_cur[i]);
6696 if (doms_new == NULL) {
6698 doms_new = &fallback_doms;
6699 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6700 WARN_ON_ONCE(dattr_new);
6703 /* Build new domains */
6704 for (i = 0; i < ndoms_new; i++) {
6705 for (j = 0; j < n && !new_topology; j++) {
6706 if (cpumask_equal(doms_new[i], doms_cur[j])
6707 && dattrs_equal(dattr_new, i, dattr_cur, j))
6710 /* no match - add a new doms_new */
6711 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6716 /* Remember the new sched domains */
6717 if (doms_cur != &fallback_doms)
6718 free_sched_domains(doms_cur, ndoms_cur);
6719 kfree(dattr_cur); /* kfree(NULL) is safe */
6720 doms_cur = doms_new;
6721 dattr_cur = dattr_new;
6722 ndoms_cur = ndoms_new;
6724 register_sched_domain_sysctl();
6726 mutex_unlock(&sched_domains_mutex);
6729 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
6732 * Update cpusets according to cpu_active mask. If cpusets are
6733 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6734 * around partition_sched_domains().
6736 * If we come here as part of a suspend/resume, don't touch cpusets because we
6737 * want to restore it back to its original state upon resume anyway.
6739 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6743 case CPU_ONLINE_FROZEN:
6744 case CPU_DOWN_FAILED_FROZEN:
6747 * num_cpus_frozen tracks how many CPUs are involved in suspend
6748 * resume sequence. As long as this is not the last online
6749 * operation in the resume sequence, just build a single sched
6750 * domain, ignoring cpusets.
6753 if (likely(num_cpus_frozen)) {
6754 partition_sched_domains(1, NULL, NULL);
6759 * This is the last CPU online operation. So fall through and
6760 * restore the original sched domains by considering the
6761 * cpuset configurations.
6765 case CPU_DOWN_FAILED:
6766 cpuset_update_active_cpus(true);
6774 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6778 case CPU_DOWN_PREPARE:
6779 cpuset_update_active_cpus(false);
6781 case CPU_DOWN_PREPARE_FROZEN:
6783 partition_sched_domains(1, NULL, NULL);
6791 void __init sched_init_smp(void)
6793 cpumask_var_t non_isolated_cpus;
6795 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6796 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6801 * There's no userspace yet to cause hotplug operations; hence all the
6802 * cpu masks are stable and all blatant races in the below code cannot
6805 mutex_lock(&sched_domains_mutex);
6806 init_sched_domains(cpu_active_mask);
6807 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6808 if (cpumask_empty(non_isolated_cpus))
6809 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6810 mutex_unlock(&sched_domains_mutex);
6812 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6813 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6814 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6818 /* Move init over to a non-isolated CPU */
6819 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6821 sched_init_granularity();
6822 free_cpumask_var(non_isolated_cpus);
6824 init_sched_rt_class();
6825 init_sched_dl_class();
6828 void __init sched_init_smp(void)
6830 sched_init_granularity();
6832 #endif /* CONFIG_SMP */
6834 const_debug unsigned int sysctl_timer_migration = 1;
6836 int in_sched_functions(unsigned long addr)
6838 return in_lock_functions(addr) ||
6839 (addr >= (unsigned long)__sched_text_start
6840 && addr < (unsigned long)__sched_text_end);
6843 #ifdef CONFIG_CGROUP_SCHED
6845 * Default task group.
6846 * Every task in system belongs to this group at bootup.
6848 struct task_group root_task_group;
6849 LIST_HEAD(task_groups);
6852 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6854 void __init sched_init(void)
6857 unsigned long alloc_size = 0, ptr;
6859 #ifdef CONFIG_FAIR_GROUP_SCHED
6860 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6862 #ifdef CONFIG_RT_GROUP_SCHED
6863 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6865 #ifdef CONFIG_CPUMASK_OFFSTACK
6866 alloc_size += num_possible_cpus() * cpumask_size();
6869 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6871 #ifdef CONFIG_FAIR_GROUP_SCHED
6872 root_task_group.se = (struct sched_entity **)ptr;
6873 ptr += nr_cpu_ids * sizeof(void **);
6875 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6876 ptr += nr_cpu_ids * sizeof(void **);
6878 #endif /* CONFIG_FAIR_GROUP_SCHED */
6879 #ifdef CONFIG_RT_GROUP_SCHED
6880 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
6881 ptr += nr_cpu_ids * sizeof(void **);
6883 root_task_group.rt_rq = (struct rt_rq **)ptr;
6884 ptr += nr_cpu_ids * sizeof(void **);
6886 #endif /* CONFIG_RT_GROUP_SCHED */
6887 #ifdef CONFIG_CPUMASK_OFFSTACK
6888 for_each_possible_cpu(i) {
6889 per_cpu(load_balance_mask, i) = (void *)ptr;
6890 ptr += cpumask_size();
6892 #endif /* CONFIG_CPUMASK_OFFSTACK */
6895 init_rt_bandwidth(&def_rt_bandwidth,
6896 global_rt_period(), global_rt_runtime());
6897 init_dl_bandwidth(&def_dl_bandwidth,
6898 global_rt_period(), global_rt_runtime());
6901 init_defrootdomain();
6904 #ifdef CONFIG_RT_GROUP_SCHED
6905 init_rt_bandwidth(&root_task_group.rt_bandwidth,
6906 global_rt_period(), global_rt_runtime());
6907 #endif /* CONFIG_RT_GROUP_SCHED */
6909 #ifdef CONFIG_CGROUP_SCHED
6910 list_add(&root_task_group.list, &task_groups);
6911 INIT_LIST_HEAD(&root_task_group.children);
6912 INIT_LIST_HEAD(&root_task_group.siblings);
6913 autogroup_init(&init_task);
6915 #endif /* CONFIG_CGROUP_SCHED */
6917 for_each_possible_cpu(i) {
6921 raw_spin_lock_init(&rq->lock);
6923 rq->calc_load_active = 0;
6924 rq->calc_load_update = jiffies + LOAD_FREQ;
6925 init_cfs_rq(&rq->cfs);
6926 init_rt_rq(&rq->rt, rq);
6927 init_dl_rq(&rq->dl, rq);
6928 #ifdef CONFIG_FAIR_GROUP_SCHED
6929 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
6930 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
6932 * How much cpu bandwidth does root_task_group get?
6934 * In case of task-groups formed thr' the cgroup filesystem, it
6935 * gets 100% of the cpu resources in the system. This overall
6936 * system cpu resource is divided among the tasks of
6937 * root_task_group and its child task-groups in a fair manner,
6938 * based on each entity's (task or task-group's) weight
6939 * (se->load.weight).
6941 * In other words, if root_task_group has 10 tasks of weight
6942 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6943 * then A0's share of the cpu resource is:
6945 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6947 * We achieve this by letting root_task_group's tasks sit
6948 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6950 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
6951 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
6952 #endif /* CONFIG_FAIR_GROUP_SCHED */
6954 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
6955 #ifdef CONFIG_RT_GROUP_SCHED
6956 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
6959 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
6960 rq->cpu_load[j] = 0;
6962 rq->last_load_update_tick = jiffies;
6967 rq->cpu_capacity = SCHED_CAPACITY_SCALE;
6968 rq->post_schedule = 0;
6969 rq->active_balance = 0;
6970 rq->next_balance = jiffies;
6975 rq->avg_idle = 2*sysctl_sched_migration_cost;
6976 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
6978 INIT_LIST_HEAD(&rq->cfs_tasks);
6980 rq_attach_root(rq, &def_root_domain);
6981 #ifdef CONFIG_NO_HZ_COMMON
6984 #ifdef CONFIG_NO_HZ_FULL
6985 rq->last_sched_tick = 0;
6989 atomic_set(&rq->nr_iowait, 0);
6992 set_load_weight(&init_task);
6994 #ifdef CONFIG_PREEMPT_NOTIFIERS
6995 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
6999 * The boot idle thread does lazy MMU switching as well:
7001 atomic_inc(&init_mm.mm_count);
7002 enter_lazy_tlb(&init_mm, current);
7005 * Make us the idle thread. Technically, schedule() should not be
7006 * called from this thread, however somewhere below it might be,
7007 * but because we are the idle thread, we just pick up running again
7008 * when this runqueue becomes "idle".
7010 init_idle(current, smp_processor_id());
7012 calc_load_update = jiffies + LOAD_FREQ;
7015 * During early bootup we pretend to be a normal task:
7017 current->sched_class = &fair_sched_class;
7020 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7021 /* May be allocated at isolcpus cmdline parse time */
7022 if (cpu_isolated_map == NULL)
7023 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7024 idle_thread_set_boot_cpu();
7025 set_cpu_rq_start_time();
7027 init_sched_fair_class();
7029 scheduler_running = 1;
7032 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7033 static inline int preempt_count_equals(int preempt_offset)
7035 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
7037 return (nested == preempt_offset);
7040 void __might_sleep(const char *file, int line, int preempt_offset)
7042 static unsigned long prev_jiffy; /* ratelimiting */
7044 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7045 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7046 !is_idle_task(current)) ||
7047 system_state != SYSTEM_RUNNING || oops_in_progress)
7049 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7051 prev_jiffy = jiffies;
7054 "BUG: sleeping function called from invalid context at %s:%d\n",
7057 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7058 in_atomic(), irqs_disabled(),
7059 current->pid, current->comm);
7061 debug_show_held_locks(current);
7062 if (irqs_disabled())
7063 print_irqtrace_events(current);
7064 #ifdef CONFIG_DEBUG_PREEMPT
7065 if (!preempt_count_equals(preempt_offset)) {
7066 pr_err("Preemption disabled at:");
7067 print_ip_sym(current->preempt_disable_ip);
7073 EXPORT_SYMBOL(__might_sleep);
7076 #ifdef CONFIG_MAGIC_SYSRQ
7077 static void normalize_task(struct rq *rq, struct task_struct *p)
7079 const struct sched_class *prev_class = p->sched_class;
7080 struct sched_attr attr = {
7081 .sched_policy = SCHED_NORMAL,
7083 int old_prio = p->prio;
7088 dequeue_task(rq, p, 0);
7089 __setscheduler(rq, p, &attr);
7091 enqueue_task(rq, p, 0);
7092 resched_task(rq->curr);
7095 check_class_changed(rq, p, prev_class, old_prio);
7098 void normalize_rt_tasks(void)
7100 struct task_struct *g, *p;
7101 unsigned long flags;
7104 read_lock_irqsave(&tasklist_lock, flags);
7105 do_each_thread(g, p) {
7107 * Only normalize user tasks:
7112 p->se.exec_start = 0;
7113 #ifdef CONFIG_SCHEDSTATS
7114 p->se.statistics.wait_start = 0;
7115 p->se.statistics.sleep_start = 0;
7116 p->se.statistics.block_start = 0;
7119 if (!dl_task(p) && !rt_task(p)) {
7121 * Renice negative nice level userspace
7124 if (task_nice(p) < 0 && p->mm)
7125 set_user_nice(p, 0);
7129 raw_spin_lock(&p->pi_lock);
7130 rq = __task_rq_lock(p);
7132 normalize_task(rq, p);
7134 __task_rq_unlock(rq);
7135 raw_spin_unlock(&p->pi_lock);
7136 } while_each_thread(g, p);
7138 read_unlock_irqrestore(&tasklist_lock, flags);
7141 #endif /* CONFIG_MAGIC_SYSRQ */
7143 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7145 * These functions are only useful for the IA64 MCA handling, or kdb.
7147 * They can only be called when the whole system has been
7148 * stopped - every CPU needs to be quiescent, and no scheduling
7149 * activity can take place. Using them for anything else would
7150 * be a serious bug, and as a result, they aren't even visible
7151 * under any other configuration.
7155 * curr_task - return the current task for a given cpu.
7156 * @cpu: the processor in question.
7158 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7160 * Return: The current task for @cpu.
7162 struct task_struct *curr_task(int cpu)
7164 return cpu_curr(cpu);
7167 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7171 * set_curr_task - set the current task for a given cpu.
7172 * @cpu: the processor in question.
7173 * @p: the task pointer to set.
7175 * Description: This function must only be used when non-maskable interrupts
7176 * are serviced on a separate stack. It allows the architecture to switch the
7177 * notion of the current task on a cpu in a non-blocking manner. This function
7178 * must be called with all CPU's synchronized, and interrupts disabled, the
7179 * and caller must save the original value of the current task (see
7180 * curr_task() above) and restore that value before reenabling interrupts and
7181 * re-starting the system.
7183 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7185 void set_curr_task(int cpu, struct task_struct *p)
7192 #ifdef CONFIG_CGROUP_SCHED
7193 /* task_group_lock serializes the addition/removal of task groups */
7194 static DEFINE_SPINLOCK(task_group_lock);
7196 static void free_sched_group(struct task_group *tg)
7198 free_fair_sched_group(tg);
7199 free_rt_sched_group(tg);
7204 /* allocate runqueue etc for a new task group */
7205 struct task_group *sched_create_group(struct task_group *parent)
7207 struct task_group *tg;
7209 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7211 return ERR_PTR(-ENOMEM);
7213 if (!alloc_fair_sched_group(tg, parent))
7216 if (!alloc_rt_sched_group(tg, parent))
7222 free_sched_group(tg);
7223 return ERR_PTR(-ENOMEM);
7226 void sched_online_group(struct task_group *tg, struct task_group *parent)
7228 unsigned long flags;
7230 spin_lock_irqsave(&task_group_lock, flags);
7231 list_add_rcu(&tg->list, &task_groups);
7233 WARN_ON(!parent); /* root should already exist */
7235 tg->parent = parent;
7236 INIT_LIST_HEAD(&tg->children);
7237 list_add_rcu(&tg->siblings, &parent->children);
7238 spin_unlock_irqrestore(&task_group_lock, flags);
7241 /* rcu callback to free various structures associated with a task group */
7242 static void free_sched_group_rcu(struct rcu_head *rhp)
7244 /* now it should be safe to free those cfs_rqs */
7245 free_sched_group(container_of(rhp, struct task_group, rcu));
7248 /* Destroy runqueue etc associated with a task group */
7249 void sched_destroy_group(struct task_group *tg)
7251 /* wait for possible concurrent references to cfs_rqs complete */
7252 call_rcu(&tg->rcu, free_sched_group_rcu);
7255 void sched_offline_group(struct task_group *tg)
7257 unsigned long flags;
7260 /* end participation in shares distribution */
7261 for_each_possible_cpu(i)
7262 unregister_fair_sched_group(tg, i);
7264 spin_lock_irqsave(&task_group_lock, flags);
7265 list_del_rcu(&tg->list);
7266 list_del_rcu(&tg->siblings);
7267 spin_unlock_irqrestore(&task_group_lock, flags);
7270 /* change task's runqueue when it moves between groups.
7271 * The caller of this function should have put the task in its new group
7272 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7273 * reflect its new group.
7275 void sched_move_task(struct task_struct *tsk)
7277 struct task_group *tg;
7279 unsigned long flags;
7282 rq = task_rq_lock(tsk, &flags);
7284 running = task_current(rq, tsk);
7288 dequeue_task(rq, tsk, 0);
7289 if (unlikely(running))
7290 tsk->sched_class->put_prev_task(rq, tsk);
7292 tg = container_of(task_css_check(tsk, cpu_cgrp_id,
7293 lockdep_is_held(&tsk->sighand->siglock)),
7294 struct task_group, css);
7295 tg = autogroup_task_group(tsk, tg);
7296 tsk->sched_task_group = tg;
7298 #ifdef CONFIG_FAIR_GROUP_SCHED
7299 if (tsk->sched_class->task_move_group)
7300 tsk->sched_class->task_move_group(tsk, on_rq);
7303 set_task_rq(tsk, task_cpu(tsk));
7305 if (unlikely(running))
7306 tsk->sched_class->set_curr_task(rq);
7308 enqueue_task(rq, tsk, 0);
7310 task_rq_unlock(rq, tsk, &flags);
7312 #endif /* CONFIG_CGROUP_SCHED */
7314 #ifdef CONFIG_RT_GROUP_SCHED
7316 * Ensure that the real time constraints are schedulable.
7318 static DEFINE_MUTEX(rt_constraints_mutex);
7320 /* Must be called with tasklist_lock held */
7321 static inline int tg_has_rt_tasks(struct task_group *tg)
7323 struct task_struct *g, *p;
7325 do_each_thread(g, p) {
7326 if (rt_task(p) && task_rq(p)->rt.tg == tg)
7328 } while_each_thread(g, p);
7333 struct rt_schedulable_data {
7334 struct task_group *tg;
7339 static int tg_rt_schedulable(struct task_group *tg, void *data)
7341 struct rt_schedulable_data *d = data;
7342 struct task_group *child;
7343 unsigned long total, sum = 0;
7344 u64 period, runtime;
7346 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7347 runtime = tg->rt_bandwidth.rt_runtime;
7350 period = d->rt_period;
7351 runtime = d->rt_runtime;
7355 * Cannot have more runtime than the period.
7357 if (runtime > period && runtime != RUNTIME_INF)
7361 * Ensure we don't starve existing RT tasks.
7363 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7366 total = to_ratio(period, runtime);
7369 * Nobody can have more than the global setting allows.
7371 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7375 * The sum of our children's runtime should not exceed our own.
7377 list_for_each_entry_rcu(child, &tg->children, siblings) {
7378 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7379 runtime = child->rt_bandwidth.rt_runtime;
7381 if (child == d->tg) {
7382 period = d->rt_period;
7383 runtime = d->rt_runtime;
7386 sum += to_ratio(period, runtime);
7395 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7399 struct rt_schedulable_data data = {
7401 .rt_period = period,
7402 .rt_runtime = runtime,
7406 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7412 static int tg_set_rt_bandwidth(struct task_group *tg,
7413 u64 rt_period, u64 rt_runtime)
7417 mutex_lock(&rt_constraints_mutex);
7418 read_lock(&tasklist_lock);
7419 err = __rt_schedulable(tg, rt_period, rt_runtime);
7423 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7424 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7425 tg->rt_bandwidth.rt_runtime = rt_runtime;
7427 for_each_possible_cpu(i) {
7428 struct rt_rq *rt_rq = tg->rt_rq[i];
7430 raw_spin_lock(&rt_rq->rt_runtime_lock);
7431 rt_rq->rt_runtime = rt_runtime;
7432 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7434 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7436 read_unlock(&tasklist_lock);
7437 mutex_unlock(&rt_constraints_mutex);
7442 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7444 u64 rt_runtime, rt_period;
7446 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7447 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7448 if (rt_runtime_us < 0)
7449 rt_runtime = RUNTIME_INF;
7451 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7454 static long sched_group_rt_runtime(struct task_group *tg)
7458 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7461 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7462 do_div(rt_runtime_us, NSEC_PER_USEC);
7463 return rt_runtime_us;
7466 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
7468 u64 rt_runtime, rt_period;
7470 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
7471 rt_runtime = tg->rt_bandwidth.rt_runtime;
7476 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7479 static long sched_group_rt_period(struct task_group *tg)
7483 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7484 do_div(rt_period_us, NSEC_PER_USEC);
7485 return rt_period_us;
7487 #endif /* CONFIG_RT_GROUP_SCHED */
7489 #ifdef CONFIG_RT_GROUP_SCHED
7490 static int sched_rt_global_constraints(void)
7494 mutex_lock(&rt_constraints_mutex);
7495 read_lock(&tasklist_lock);
7496 ret = __rt_schedulable(NULL, 0, 0);
7497 read_unlock(&tasklist_lock);
7498 mutex_unlock(&rt_constraints_mutex);
7503 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7505 /* Don't accept realtime tasks when there is no way for them to run */
7506 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7512 #else /* !CONFIG_RT_GROUP_SCHED */
7513 static int sched_rt_global_constraints(void)
7515 unsigned long flags;
7518 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7519 for_each_possible_cpu(i) {
7520 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7522 raw_spin_lock(&rt_rq->rt_runtime_lock);
7523 rt_rq->rt_runtime = global_rt_runtime();
7524 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7526 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7530 #endif /* CONFIG_RT_GROUP_SCHED */
7532 static int sched_dl_global_constraints(void)
7534 u64 runtime = global_rt_runtime();
7535 u64 period = global_rt_period();
7536 u64 new_bw = to_ratio(period, runtime);
7538 unsigned long flags;
7541 * Here we want to check the bandwidth not being set to some
7542 * value smaller than the currently allocated bandwidth in
7543 * any of the root_domains.
7545 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7546 * cycling on root_domains... Discussion on different/better
7547 * solutions is welcome!
7549 for_each_possible_cpu(cpu) {
7550 struct dl_bw *dl_b = dl_bw_of(cpu);
7552 raw_spin_lock_irqsave(&dl_b->lock, flags);
7553 if (new_bw < dl_b->total_bw)
7555 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7564 static void sched_dl_do_global(void)
7568 unsigned long flags;
7570 def_dl_bandwidth.dl_period = global_rt_period();
7571 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7573 if (global_rt_runtime() != RUNTIME_INF)
7574 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7577 * FIXME: As above...
7579 for_each_possible_cpu(cpu) {
7580 struct dl_bw *dl_b = dl_bw_of(cpu);
7582 raw_spin_lock_irqsave(&dl_b->lock, flags);
7584 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7588 static int sched_rt_global_validate(void)
7590 if (sysctl_sched_rt_period <= 0)
7593 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7594 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7600 static void sched_rt_do_global(void)
7602 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7603 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7606 int sched_rt_handler(struct ctl_table *table, int write,
7607 void __user *buffer, size_t *lenp,
7610 int old_period, old_runtime;
7611 static DEFINE_MUTEX(mutex);
7615 old_period = sysctl_sched_rt_period;
7616 old_runtime = sysctl_sched_rt_runtime;
7618 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7620 if (!ret && write) {
7621 ret = sched_rt_global_validate();
7625 ret = sched_rt_global_constraints();
7629 ret = sched_dl_global_constraints();
7633 sched_rt_do_global();
7634 sched_dl_do_global();
7638 sysctl_sched_rt_period = old_period;
7639 sysctl_sched_rt_runtime = old_runtime;
7641 mutex_unlock(&mutex);
7646 int sched_rr_handler(struct ctl_table *table, int write,
7647 void __user *buffer, size_t *lenp,
7651 static DEFINE_MUTEX(mutex);
7654 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7655 /* make sure that internally we keep jiffies */
7656 /* also, writing zero resets timeslice to default */
7657 if (!ret && write) {
7658 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
7659 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
7661 mutex_unlock(&mutex);
7665 #ifdef CONFIG_CGROUP_SCHED
7667 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
7669 return css ? container_of(css, struct task_group, css) : NULL;
7672 static struct cgroup_subsys_state *
7673 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
7675 struct task_group *parent = css_tg(parent_css);
7676 struct task_group *tg;
7679 /* This is early initialization for the top cgroup */
7680 return &root_task_group.css;
7683 tg = sched_create_group(parent);
7685 return ERR_PTR(-ENOMEM);
7690 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
7692 struct task_group *tg = css_tg(css);
7693 struct task_group *parent = css_tg(css_parent(css));
7696 sched_online_group(tg, parent);
7700 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
7702 struct task_group *tg = css_tg(css);
7704 sched_destroy_group(tg);
7707 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
7709 struct task_group *tg = css_tg(css);
7711 sched_offline_group(tg);
7714 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
7715 struct cgroup_taskset *tset)
7717 struct task_struct *task;
7719 cgroup_taskset_for_each(task, tset) {
7720 #ifdef CONFIG_RT_GROUP_SCHED
7721 if (!sched_rt_can_attach(css_tg(css), task))
7724 /* We don't support RT-tasks being in separate groups */
7725 if (task->sched_class != &fair_sched_class)
7732 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
7733 struct cgroup_taskset *tset)
7735 struct task_struct *task;
7737 cgroup_taskset_for_each(task, tset)
7738 sched_move_task(task);
7741 static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7742 struct cgroup_subsys_state *old_css,
7743 struct task_struct *task)
7746 * cgroup_exit() is called in the copy_process() failure path.
7747 * Ignore this case since the task hasn't ran yet, this avoids
7748 * trying to poke a half freed task state from generic code.
7750 if (!(task->flags & PF_EXITING))
7753 sched_move_task(task);
7756 #ifdef CONFIG_FAIR_GROUP_SCHED
7757 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7758 struct cftype *cftype, u64 shareval)
7760 return sched_group_set_shares(css_tg(css), scale_load(shareval));
7763 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7766 struct task_group *tg = css_tg(css);
7768 return (u64) scale_load_down(tg->shares);
7771 #ifdef CONFIG_CFS_BANDWIDTH
7772 static DEFINE_MUTEX(cfs_constraints_mutex);
7774 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7775 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7777 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7779 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7781 int i, ret = 0, runtime_enabled, runtime_was_enabled;
7782 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7784 if (tg == &root_task_group)
7788 * Ensure we have at some amount of bandwidth every period. This is
7789 * to prevent reaching a state of large arrears when throttled via
7790 * entity_tick() resulting in prolonged exit starvation.
7792 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7796 * Likewise, bound things on the otherside by preventing insane quota
7797 * periods. This also allows us to normalize in computing quota
7800 if (period > max_cfs_quota_period)
7803 mutex_lock(&cfs_constraints_mutex);
7804 ret = __cfs_schedulable(tg, period, quota);
7808 runtime_enabled = quota != RUNTIME_INF;
7809 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7811 * If we need to toggle cfs_bandwidth_used, off->on must occur
7812 * before making related changes, and on->off must occur afterwards
7814 if (runtime_enabled && !runtime_was_enabled)
7815 cfs_bandwidth_usage_inc();
7816 raw_spin_lock_irq(&cfs_b->lock);
7817 cfs_b->period = ns_to_ktime(period);
7818 cfs_b->quota = quota;
7820 __refill_cfs_bandwidth_runtime(cfs_b);
7821 /* restart the period timer (if active) to handle new period expiry */
7822 if (runtime_enabled && cfs_b->timer_active) {
7823 /* force a reprogram */
7824 cfs_b->timer_active = 0;
7825 __start_cfs_bandwidth(cfs_b);
7827 raw_spin_unlock_irq(&cfs_b->lock);
7829 for_each_possible_cpu(i) {
7830 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7831 struct rq *rq = cfs_rq->rq;
7833 raw_spin_lock_irq(&rq->lock);
7834 cfs_rq->runtime_enabled = runtime_enabled;
7835 cfs_rq->runtime_remaining = 0;
7837 if (cfs_rq->throttled)
7838 unthrottle_cfs_rq(cfs_rq);
7839 raw_spin_unlock_irq(&rq->lock);
7841 if (runtime_was_enabled && !runtime_enabled)
7842 cfs_bandwidth_usage_dec();
7844 mutex_unlock(&cfs_constraints_mutex);
7849 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7853 period = ktime_to_ns(tg->cfs_bandwidth.period);
7854 if (cfs_quota_us < 0)
7855 quota = RUNTIME_INF;
7857 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7859 return tg_set_cfs_bandwidth(tg, period, quota);
7862 long tg_get_cfs_quota(struct task_group *tg)
7866 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7869 quota_us = tg->cfs_bandwidth.quota;
7870 do_div(quota_us, NSEC_PER_USEC);
7875 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
7879 period = (u64)cfs_period_us * NSEC_PER_USEC;
7880 quota = tg->cfs_bandwidth.quota;
7882 return tg_set_cfs_bandwidth(tg, period, quota);
7885 long tg_get_cfs_period(struct task_group *tg)
7889 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
7890 do_div(cfs_period_us, NSEC_PER_USEC);
7892 return cfs_period_us;
7895 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
7898 return tg_get_cfs_quota(css_tg(css));
7901 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
7902 struct cftype *cftype, s64 cfs_quota_us)
7904 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
7907 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
7910 return tg_get_cfs_period(css_tg(css));
7913 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
7914 struct cftype *cftype, u64 cfs_period_us)
7916 return tg_set_cfs_period(css_tg(css), cfs_period_us);
7919 struct cfs_schedulable_data {
7920 struct task_group *tg;
7925 * normalize group quota/period to be quota/max_period
7926 * note: units are usecs
7928 static u64 normalize_cfs_quota(struct task_group *tg,
7929 struct cfs_schedulable_data *d)
7937 period = tg_get_cfs_period(tg);
7938 quota = tg_get_cfs_quota(tg);
7941 /* note: these should typically be equivalent */
7942 if (quota == RUNTIME_INF || quota == -1)
7945 return to_ratio(period, quota);
7948 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
7950 struct cfs_schedulable_data *d = data;
7951 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7952 s64 quota = 0, parent_quota = -1;
7955 quota = RUNTIME_INF;
7957 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
7959 quota = normalize_cfs_quota(tg, d);
7960 parent_quota = parent_b->hierarchal_quota;
7963 * ensure max(child_quota) <= parent_quota, inherit when no
7966 if (quota == RUNTIME_INF)
7967 quota = parent_quota;
7968 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
7971 cfs_b->hierarchal_quota = quota;
7976 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
7979 struct cfs_schedulable_data data = {
7985 if (quota != RUNTIME_INF) {
7986 do_div(data.period, NSEC_PER_USEC);
7987 do_div(data.quota, NSEC_PER_USEC);
7991 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
7997 static int cpu_stats_show(struct seq_file *sf, void *v)
7999 struct task_group *tg = css_tg(seq_css(sf));
8000 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8002 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8003 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8004 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8008 #endif /* CONFIG_CFS_BANDWIDTH */
8009 #endif /* CONFIG_FAIR_GROUP_SCHED */
8011 #ifdef CONFIG_RT_GROUP_SCHED
8012 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8013 struct cftype *cft, s64 val)
8015 return sched_group_set_rt_runtime(css_tg(css), val);
8018 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8021 return sched_group_rt_runtime(css_tg(css));
8024 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8025 struct cftype *cftype, u64 rt_period_us)
8027 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8030 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8033 return sched_group_rt_period(css_tg(css));
8035 #endif /* CONFIG_RT_GROUP_SCHED */
8037 static struct cftype cpu_files[] = {
8038 #ifdef CONFIG_FAIR_GROUP_SCHED
8041 .read_u64 = cpu_shares_read_u64,
8042 .write_u64 = cpu_shares_write_u64,
8045 #ifdef CONFIG_CFS_BANDWIDTH
8047 .name = "cfs_quota_us",
8048 .read_s64 = cpu_cfs_quota_read_s64,
8049 .write_s64 = cpu_cfs_quota_write_s64,
8052 .name = "cfs_period_us",
8053 .read_u64 = cpu_cfs_period_read_u64,
8054 .write_u64 = cpu_cfs_period_write_u64,
8058 .seq_show = cpu_stats_show,
8061 #ifdef CONFIG_RT_GROUP_SCHED
8063 .name = "rt_runtime_us",
8064 .read_s64 = cpu_rt_runtime_read,
8065 .write_s64 = cpu_rt_runtime_write,
8068 .name = "rt_period_us",
8069 .read_u64 = cpu_rt_period_read_uint,
8070 .write_u64 = cpu_rt_period_write_uint,
8076 struct cgroup_subsys cpu_cgrp_subsys = {
8077 .css_alloc = cpu_cgroup_css_alloc,
8078 .css_free = cpu_cgroup_css_free,
8079 .css_online = cpu_cgroup_css_online,
8080 .css_offline = cpu_cgroup_css_offline,
8081 .can_attach = cpu_cgroup_can_attach,
8082 .attach = cpu_cgroup_attach,
8083 .exit = cpu_cgroup_exit,
8084 .base_cftypes = cpu_files,
8088 #endif /* CONFIG_CGROUP_SCHED */
8090 void dump_cpu_task(int cpu)
8092 pr_info("Task dump for CPU %d:\n", cpu);
8093 sched_show_task(cpu_curr(cpu));