4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/debugfs.h>
70 #include <linux/ctype.h>
71 #include <linux/ftrace.h>
72 #include <linux/slab.h>
73 #include <linux/init_task.h>
74 #include <linux/binfmts.h>
75 #include <linux/context_tracking.h>
76 #include <linux/compiler.h>
78 #include <asm/switch_to.h>
80 #include <asm/irq_regs.h>
81 #include <asm/mutex.h>
82 #ifdef CONFIG_PARAVIRT
83 #include <asm/paravirt.h>
87 #include "../workqueue_internal.h"
88 #include "../smpboot.h"
90 #define CREATE_TRACE_POINTS
91 #include <trace/events/sched.h>
93 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
96 ktime_t soft, hard, now;
99 if (hrtimer_active(period_timer))
102 now = hrtimer_cb_get_time(period_timer);
103 hrtimer_forward(period_timer, now, period);
105 soft = hrtimer_get_softexpires(period_timer);
106 hard = hrtimer_get_expires(period_timer);
107 delta = ktime_to_ns(ktime_sub(hard, soft));
108 __hrtimer_start_range_ns(period_timer, soft, delta,
109 HRTIMER_MODE_ABS_PINNED, 0);
113 DEFINE_MUTEX(sched_domains_mutex);
114 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
116 static void update_rq_clock_task(struct rq *rq, s64 delta);
118 void update_rq_clock(struct rq *rq)
122 if (rq->skip_clock_update > 0)
125 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
129 update_rq_clock_task(rq, delta);
133 * Debugging: various feature bits
136 #define SCHED_FEAT(name, enabled) \
137 (1UL << __SCHED_FEAT_##name) * enabled |
139 const_debug unsigned int sysctl_sched_features =
140 #include "features.h"
145 #ifdef CONFIG_SCHED_DEBUG
146 #define SCHED_FEAT(name, enabled) \
149 static const char * const sched_feat_names[] = {
150 #include "features.h"
155 static int sched_feat_show(struct seq_file *m, void *v)
159 for (i = 0; i < __SCHED_FEAT_NR; i++) {
160 if (!(sysctl_sched_features & (1UL << i)))
162 seq_printf(m, "%s ", sched_feat_names[i]);
169 #ifdef HAVE_JUMP_LABEL
171 #define jump_label_key__true STATIC_KEY_INIT_TRUE
172 #define jump_label_key__false STATIC_KEY_INIT_FALSE
174 #define SCHED_FEAT(name, enabled) \
175 jump_label_key__##enabled ,
177 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
178 #include "features.h"
183 static void sched_feat_disable(int i)
185 if (static_key_enabled(&sched_feat_keys[i]))
186 static_key_slow_dec(&sched_feat_keys[i]);
189 static void sched_feat_enable(int i)
191 if (!static_key_enabled(&sched_feat_keys[i]))
192 static_key_slow_inc(&sched_feat_keys[i]);
195 static void sched_feat_disable(int i) { };
196 static void sched_feat_enable(int i) { };
197 #endif /* HAVE_JUMP_LABEL */
199 static int sched_feat_set(char *cmp)
204 if (strncmp(cmp, "NO_", 3) == 0) {
209 for (i = 0; i < __SCHED_FEAT_NR; i++) {
210 if (strcmp(cmp, sched_feat_names[i]) == 0) {
212 sysctl_sched_features &= ~(1UL << i);
213 sched_feat_disable(i);
215 sysctl_sched_features |= (1UL << i);
216 sched_feat_enable(i);
226 sched_feat_write(struct file *filp, const char __user *ubuf,
227 size_t cnt, loff_t *ppos)
237 if (copy_from_user(&buf, ubuf, cnt))
243 /* Ensure the static_key remains in a consistent state */
244 inode = file_inode(filp);
245 mutex_lock(&inode->i_mutex);
246 i = sched_feat_set(cmp);
247 mutex_unlock(&inode->i_mutex);
248 if (i == __SCHED_FEAT_NR)
256 static int sched_feat_open(struct inode *inode, struct file *filp)
258 return single_open(filp, sched_feat_show, NULL);
261 static const struct file_operations sched_feat_fops = {
262 .open = sched_feat_open,
263 .write = sched_feat_write,
266 .release = single_release,
269 static __init int sched_init_debug(void)
271 debugfs_create_file("sched_features", 0644, NULL, NULL,
276 late_initcall(sched_init_debug);
277 #endif /* CONFIG_SCHED_DEBUG */
280 * Number of tasks to iterate in a single balance run.
281 * Limited because this is done with IRQs disabled.
283 const_debug unsigned int sysctl_sched_nr_migrate = 32;
286 * period over which we average the RT time consumption, measured
291 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
294 * period over which we measure -rt task cpu usage in us.
297 unsigned int sysctl_sched_rt_period = 1000000;
299 __read_mostly int scheduler_running;
302 * part of the period that we allow rt tasks to run in us.
305 int sysctl_sched_rt_runtime = 950000;
308 * __task_rq_lock - lock the rq @p resides on.
310 static inline struct rq *__task_rq_lock(struct task_struct *p)
315 lockdep_assert_held(&p->pi_lock);
319 raw_spin_lock(&rq->lock);
320 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
322 raw_spin_unlock(&rq->lock);
324 while (unlikely(task_on_rq_migrating(p)))
330 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
332 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
333 __acquires(p->pi_lock)
339 raw_spin_lock_irqsave(&p->pi_lock, *flags);
341 raw_spin_lock(&rq->lock);
342 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
344 raw_spin_unlock(&rq->lock);
345 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
347 while (unlikely(task_on_rq_migrating(p)))
352 static void __task_rq_unlock(struct rq *rq)
355 raw_spin_unlock(&rq->lock);
359 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
361 __releases(p->pi_lock)
363 raw_spin_unlock(&rq->lock);
364 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
368 * this_rq_lock - lock this runqueue and disable interrupts.
370 static struct rq *this_rq_lock(void)
377 raw_spin_lock(&rq->lock);
382 #ifdef CONFIG_SCHED_HRTICK
384 * Use HR-timers to deliver accurate preemption points.
387 static void hrtick_clear(struct rq *rq)
389 if (hrtimer_active(&rq->hrtick_timer))
390 hrtimer_cancel(&rq->hrtick_timer);
394 * High-resolution timer tick.
395 * Runs from hardirq context with interrupts disabled.
397 static enum hrtimer_restart hrtick(struct hrtimer *timer)
399 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
401 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
403 raw_spin_lock(&rq->lock);
405 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
406 raw_spin_unlock(&rq->lock);
408 return HRTIMER_NORESTART;
413 static int __hrtick_restart(struct rq *rq)
415 struct hrtimer *timer = &rq->hrtick_timer;
416 ktime_t time = hrtimer_get_softexpires(timer);
418 return __hrtimer_start_range_ns(timer, time, 0, HRTIMER_MODE_ABS_PINNED, 0);
422 * called from hardirq (IPI) context
424 static void __hrtick_start(void *arg)
428 raw_spin_lock(&rq->lock);
429 __hrtick_restart(rq);
430 rq->hrtick_csd_pending = 0;
431 raw_spin_unlock(&rq->lock);
435 * Called to set the hrtick timer state.
437 * called with rq->lock held and irqs disabled
439 void hrtick_start(struct rq *rq, u64 delay)
441 struct hrtimer *timer = &rq->hrtick_timer;
446 * Don't schedule slices shorter than 10000ns, that just
447 * doesn't make sense and can cause timer DoS.
449 delta = max_t(s64, delay, 10000LL);
450 time = ktime_add_ns(timer->base->get_time(), delta);
452 hrtimer_set_expires(timer, time);
454 if (rq == this_rq()) {
455 __hrtick_restart(rq);
456 } else if (!rq->hrtick_csd_pending) {
457 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
458 rq->hrtick_csd_pending = 1;
463 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
465 int cpu = (int)(long)hcpu;
468 case CPU_UP_CANCELED:
469 case CPU_UP_CANCELED_FROZEN:
470 case CPU_DOWN_PREPARE:
471 case CPU_DOWN_PREPARE_FROZEN:
473 case CPU_DEAD_FROZEN:
474 hrtick_clear(cpu_rq(cpu));
481 static __init void init_hrtick(void)
483 hotcpu_notifier(hotplug_hrtick, 0);
487 * Called to set the hrtick timer state.
489 * called with rq->lock held and irqs disabled
491 void hrtick_start(struct rq *rq, u64 delay)
493 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
494 HRTIMER_MODE_REL_PINNED, 0);
497 static inline void init_hrtick(void)
500 #endif /* CONFIG_SMP */
502 static void init_rq_hrtick(struct rq *rq)
505 rq->hrtick_csd_pending = 0;
507 rq->hrtick_csd.flags = 0;
508 rq->hrtick_csd.func = __hrtick_start;
509 rq->hrtick_csd.info = rq;
512 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
513 rq->hrtick_timer.function = hrtick;
515 #else /* CONFIG_SCHED_HRTICK */
516 static inline void hrtick_clear(struct rq *rq)
520 static inline void init_rq_hrtick(struct rq *rq)
524 static inline void init_hrtick(void)
527 #endif /* CONFIG_SCHED_HRTICK */
530 * cmpxchg based fetch_or, macro so it works for different integer types
532 #define fetch_or(ptr, val) \
533 ({ typeof(*(ptr)) __old, __val = *(ptr); \
535 __old = cmpxchg((ptr), __val, __val | (val)); \
536 if (__old == __val) \
543 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
545 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
546 * this avoids any races wrt polling state changes and thereby avoids
549 static bool set_nr_and_not_polling(struct task_struct *p)
551 struct thread_info *ti = task_thread_info(p);
552 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
556 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
558 * If this returns true, then the idle task promises to call
559 * sched_ttwu_pending() and reschedule soon.
561 static bool set_nr_if_polling(struct task_struct *p)
563 struct thread_info *ti = task_thread_info(p);
564 typeof(ti->flags) old, val = ACCESS_ONCE(ti->flags);
567 if (!(val & _TIF_POLLING_NRFLAG))
569 if (val & _TIF_NEED_RESCHED)
571 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
580 static bool set_nr_and_not_polling(struct task_struct *p)
582 set_tsk_need_resched(p);
587 static bool set_nr_if_polling(struct task_struct *p)
595 * resched_curr - mark rq's current task 'to be rescheduled now'.
597 * On UP this means the setting of the need_resched flag, on SMP it
598 * might also involve a cross-CPU call to trigger the scheduler on
601 void resched_curr(struct rq *rq)
603 struct task_struct *curr = rq->curr;
606 lockdep_assert_held(&rq->lock);
608 if (test_tsk_need_resched(curr))
613 if (cpu == smp_processor_id()) {
614 set_tsk_need_resched(curr);
615 set_preempt_need_resched();
619 if (set_nr_and_not_polling(curr))
620 smp_send_reschedule(cpu);
622 trace_sched_wake_idle_without_ipi(cpu);
625 void resched_cpu(int cpu)
627 struct rq *rq = cpu_rq(cpu);
630 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
633 raw_spin_unlock_irqrestore(&rq->lock, flags);
637 #ifdef CONFIG_NO_HZ_COMMON
639 * In the semi idle case, use the nearest busy cpu for migrating timers
640 * from an idle cpu. This is good for power-savings.
642 * We don't do similar optimization for completely idle system, as
643 * selecting an idle cpu will add more delays to the timers than intended
644 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
646 int get_nohz_timer_target(int pinned)
648 int cpu = smp_processor_id();
650 struct sched_domain *sd;
652 if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
656 for_each_domain(cpu, sd) {
657 for_each_cpu(i, sched_domain_span(sd)) {
669 * When add_timer_on() enqueues a timer into the timer wheel of an
670 * idle CPU then this timer might expire before the next timer event
671 * which is scheduled to wake up that CPU. In case of a completely
672 * idle system the next event might even be infinite time into the
673 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
674 * leaves the inner idle loop so the newly added timer is taken into
675 * account when the CPU goes back to idle and evaluates the timer
676 * wheel for the next timer event.
678 static void wake_up_idle_cpu(int cpu)
680 struct rq *rq = cpu_rq(cpu);
682 if (cpu == smp_processor_id())
685 if (set_nr_and_not_polling(rq->idle))
686 smp_send_reschedule(cpu);
688 trace_sched_wake_idle_without_ipi(cpu);
691 static bool wake_up_full_nohz_cpu(int cpu)
694 * We just need the target to call irq_exit() and re-evaluate
695 * the next tick. The nohz full kick at least implies that.
696 * If needed we can still optimize that later with an
699 if (tick_nohz_full_cpu(cpu)) {
700 if (cpu != smp_processor_id() ||
701 tick_nohz_tick_stopped())
702 tick_nohz_full_kick_cpu(cpu);
709 void wake_up_nohz_cpu(int cpu)
711 if (!wake_up_full_nohz_cpu(cpu))
712 wake_up_idle_cpu(cpu);
715 static inline bool got_nohz_idle_kick(void)
717 int cpu = smp_processor_id();
719 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
722 if (idle_cpu(cpu) && !need_resched())
726 * We can't run Idle Load Balance on this CPU for this time so we
727 * cancel it and clear NOHZ_BALANCE_KICK
729 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
733 #else /* CONFIG_NO_HZ_COMMON */
735 static inline bool got_nohz_idle_kick(void)
740 #endif /* CONFIG_NO_HZ_COMMON */
742 #ifdef CONFIG_NO_HZ_FULL
743 bool sched_can_stop_tick(void)
746 * More than one running task need preemption.
747 * nr_running update is assumed to be visible
748 * after IPI is sent from wakers.
750 if (this_rq()->nr_running > 1)
755 #endif /* CONFIG_NO_HZ_FULL */
757 void sched_avg_update(struct rq *rq)
759 s64 period = sched_avg_period();
761 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
763 * Inline assembly required to prevent the compiler
764 * optimising this loop into a divmod call.
765 * See __iter_div_u64_rem() for another example of this.
767 asm("" : "+rm" (rq->age_stamp));
768 rq->age_stamp += period;
773 #endif /* CONFIG_SMP */
775 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
776 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
778 * Iterate task_group tree rooted at *from, calling @down when first entering a
779 * node and @up when leaving it for the final time.
781 * Caller must hold rcu_lock or sufficient equivalent.
783 int walk_tg_tree_from(struct task_group *from,
784 tg_visitor down, tg_visitor up, void *data)
786 struct task_group *parent, *child;
792 ret = (*down)(parent, data);
795 list_for_each_entry_rcu(child, &parent->children, siblings) {
802 ret = (*up)(parent, data);
803 if (ret || parent == from)
807 parent = parent->parent;
814 int tg_nop(struct task_group *tg, void *data)
820 static void set_load_weight(struct task_struct *p)
822 int prio = p->static_prio - MAX_RT_PRIO;
823 struct load_weight *load = &p->se.load;
826 * SCHED_IDLE tasks get minimal weight:
828 if (p->policy == SCHED_IDLE) {
829 load->weight = scale_load(WEIGHT_IDLEPRIO);
830 load->inv_weight = WMULT_IDLEPRIO;
834 load->weight = scale_load(prio_to_weight[prio]);
835 load->inv_weight = prio_to_wmult[prio];
838 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
841 sched_info_queued(rq, p);
842 p->sched_class->enqueue_task(rq, p, flags);
845 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
848 sched_info_dequeued(rq, p);
849 p->sched_class->dequeue_task(rq, p, flags);
852 void activate_task(struct rq *rq, struct task_struct *p, int flags)
854 if (task_contributes_to_load(p))
855 rq->nr_uninterruptible--;
857 enqueue_task(rq, p, flags);
860 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
862 if (task_contributes_to_load(p))
863 rq->nr_uninterruptible++;
865 dequeue_task(rq, p, flags);
868 static void update_rq_clock_task(struct rq *rq, s64 delta)
871 * In theory, the compile should just see 0 here, and optimize out the call
872 * to sched_rt_avg_update. But I don't trust it...
874 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
875 s64 steal = 0, irq_delta = 0;
877 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
878 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
881 * Since irq_time is only updated on {soft,}irq_exit, we might run into
882 * this case when a previous update_rq_clock() happened inside a
885 * When this happens, we stop ->clock_task and only update the
886 * prev_irq_time stamp to account for the part that fit, so that a next
887 * update will consume the rest. This ensures ->clock_task is
890 * It does however cause some slight miss-attribution of {soft,}irq
891 * time, a more accurate solution would be to update the irq_time using
892 * the current rq->clock timestamp, except that would require using
895 if (irq_delta > delta)
898 rq->prev_irq_time += irq_delta;
901 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
902 if (static_key_false((¶virt_steal_rq_enabled))) {
903 steal = paravirt_steal_clock(cpu_of(rq));
904 steal -= rq->prev_steal_time_rq;
906 if (unlikely(steal > delta))
909 rq->prev_steal_time_rq += steal;
914 rq->clock_task += delta;
916 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
917 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
918 sched_rt_avg_update(rq, irq_delta + steal);
922 void sched_set_stop_task(int cpu, struct task_struct *stop)
924 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
925 struct task_struct *old_stop = cpu_rq(cpu)->stop;
929 * Make it appear like a SCHED_FIFO task, its something
930 * userspace knows about and won't get confused about.
932 * Also, it will make PI more or less work without too
933 * much confusion -- but then, stop work should not
934 * rely on PI working anyway.
936 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
938 stop->sched_class = &stop_sched_class;
941 cpu_rq(cpu)->stop = stop;
945 * Reset it back to a normal scheduling class so that
946 * it can die in pieces.
948 old_stop->sched_class = &rt_sched_class;
953 * __normal_prio - return the priority that is based on the static prio
955 static inline int __normal_prio(struct task_struct *p)
957 return p->static_prio;
961 * Calculate the expected normal priority: i.e. priority
962 * without taking RT-inheritance into account. Might be
963 * boosted by interactivity modifiers. Changes upon fork,
964 * setprio syscalls, and whenever the interactivity
965 * estimator recalculates.
967 static inline int normal_prio(struct task_struct *p)
971 if (task_has_dl_policy(p))
972 prio = MAX_DL_PRIO-1;
973 else if (task_has_rt_policy(p))
974 prio = MAX_RT_PRIO-1 - p->rt_priority;
976 prio = __normal_prio(p);
981 * Calculate the current priority, i.e. the priority
982 * taken into account by the scheduler. This value might
983 * be boosted by RT tasks, or might be boosted by
984 * interactivity modifiers. Will be RT if the task got
985 * RT-boosted. If not then it returns p->normal_prio.
987 static int effective_prio(struct task_struct *p)
989 p->normal_prio = normal_prio(p);
991 * If we are RT tasks or we were boosted to RT priority,
992 * keep the priority unchanged. Otherwise, update priority
993 * to the normal priority:
995 if (!rt_prio(p->prio))
996 return p->normal_prio;
1001 * task_curr - is this task currently executing on a CPU?
1002 * @p: the task in question.
1004 * Return: 1 if the task is currently executing. 0 otherwise.
1006 inline int task_curr(const struct task_struct *p)
1008 return cpu_curr(task_cpu(p)) == p;
1011 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1012 const struct sched_class *prev_class,
1015 if (prev_class != p->sched_class) {
1016 if (prev_class->switched_from)
1017 prev_class->switched_from(rq, p);
1018 p->sched_class->switched_to(rq, p);
1019 } else if (oldprio != p->prio || dl_task(p))
1020 p->sched_class->prio_changed(rq, p, oldprio);
1023 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
1025 const struct sched_class *class;
1027 if (p->sched_class == rq->curr->sched_class) {
1028 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
1030 for_each_class(class) {
1031 if (class == rq->curr->sched_class)
1033 if (class == p->sched_class) {
1041 * A queue event has occurred, and we're going to schedule. In
1042 * this case, we can save a useless back to back clock update.
1044 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
1045 rq->skip_clock_update = 1;
1049 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1051 #ifdef CONFIG_SCHED_DEBUG
1053 * We should never call set_task_cpu() on a blocked task,
1054 * ttwu() will sort out the placement.
1056 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1057 !(task_preempt_count(p) & PREEMPT_ACTIVE));
1059 #ifdef CONFIG_LOCKDEP
1061 * The caller should hold either p->pi_lock or rq->lock, when changing
1062 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1064 * sched_move_task() holds both and thus holding either pins the cgroup,
1067 * Furthermore, all task_rq users should acquire both locks, see
1070 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1071 lockdep_is_held(&task_rq(p)->lock)));
1075 trace_sched_migrate_task(p, new_cpu);
1077 if (task_cpu(p) != new_cpu) {
1078 if (p->sched_class->migrate_task_rq)
1079 p->sched_class->migrate_task_rq(p, new_cpu);
1080 p->se.nr_migrations++;
1081 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1084 __set_task_cpu(p, new_cpu);
1087 static void __migrate_swap_task(struct task_struct *p, int cpu)
1089 if (task_on_rq_queued(p)) {
1090 struct rq *src_rq, *dst_rq;
1092 src_rq = task_rq(p);
1093 dst_rq = cpu_rq(cpu);
1095 deactivate_task(src_rq, p, 0);
1096 set_task_cpu(p, cpu);
1097 activate_task(dst_rq, p, 0);
1098 check_preempt_curr(dst_rq, p, 0);
1101 * Task isn't running anymore; make it appear like we migrated
1102 * it before it went to sleep. This means on wakeup we make the
1103 * previous cpu our targer instead of where it really is.
1109 struct migration_swap_arg {
1110 struct task_struct *src_task, *dst_task;
1111 int src_cpu, dst_cpu;
1114 static int migrate_swap_stop(void *data)
1116 struct migration_swap_arg *arg = data;
1117 struct rq *src_rq, *dst_rq;
1120 src_rq = cpu_rq(arg->src_cpu);
1121 dst_rq = cpu_rq(arg->dst_cpu);
1123 double_raw_lock(&arg->src_task->pi_lock,
1124 &arg->dst_task->pi_lock);
1125 double_rq_lock(src_rq, dst_rq);
1126 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1129 if (task_cpu(arg->src_task) != arg->src_cpu)
1132 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1135 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1138 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1139 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1144 double_rq_unlock(src_rq, dst_rq);
1145 raw_spin_unlock(&arg->dst_task->pi_lock);
1146 raw_spin_unlock(&arg->src_task->pi_lock);
1152 * Cross migrate two tasks
1154 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1156 struct migration_swap_arg arg;
1159 arg = (struct migration_swap_arg){
1161 .src_cpu = task_cpu(cur),
1163 .dst_cpu = task_cpu(p),
1166 if (arg.src_cpu == arg.dst_cpu)
1170 * These three tests are all lockless; this is OK since all of them
1171 * will be re-checked with proper locks held further down the line.
1173 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1176 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1179 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1182 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1183 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1189 struct migration_arg {
1190 struct task_struct *task;
1194 static int migration_cpu_stop(void *data);
1197 * wait_task_inactive - wait for a thread to unschedule.
1199 * If @match_state is nonzero, it's the @p->state value just checked and
1200 * not expected to change. If it changes, i.e. @p might have woken up,
1201 * then return zero. When we succeed in waiting for @p to be off its CPU,
1202 * we return a positive number (its total switch count). If a second call
1203 * a short while later returns the same number, the caller can be sure that
1204 * @p has remained unscheduled the whole time.
1206 * The caller must ensure that the task *will* unschedule sometime soon,
1207 * else this function might spin for a *long* time. This function can't
1208 * be called with interrupts off, or it may introduce deadlock with
1209 * smp_call_function() if an IPI is sent by the same process we are
1210 * waiting to become inactive.
1212 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1214 unsigned long flags;
1215 int running, queued;
1221 * We do the initial early heuristics without holding
1222 * any task-queue locks at all. We'll only try to get
1223 * the runqueue lock when things look like they will
1229 * If the task is actively running on another CPU
1230 * still, just relax and busy-wait without holding
1233 * NOTE! Since we don't hold any locks, it's not
1234 * even sure that "rq" stays as the right runqueue!
1235 * But we don't care, since "task_running()" will
1236 * return false if the runqueue has changed and p
1237 * is actually now running somewhere else!
1239 while (task_running(rq, p)) {
1240 if (match_state && unlikely(p->state != match_state))
1246 * Ok, time to look more closely! We need the rq
1247 * lock now, to be *sure*. If we're wrong, we'll
1248 * just go back and repeat.
1250 rq = task_rq_lock(p, &flags);
1251 trace_sched_wait_task(p);
1252 running = task_running(rq, p);
1253 queued = task_on_rq_queued(p);
1255 if (!match_state || p->state == match_state)
1256 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1257 task_rq_unlock(rq, p, &flags);
1260 * If it changed from the expected state, bail out now.
1262 if (unlikely(!ncsw))
1266 * Was it really running after all now that we
1267 * checked with the proper locks actually held?
1269 * Oops. Go back and try again..
1271 if (unlikely(running)) {
1277 * It's not enough that it's not actively running,
1278 * it must be off the runqueue _entirely_, and not
1281 * So if it was still runnable (but just not actively
1282 * running right now), it's preempted, and we should
1283 * yield - it could be a while.
1285 if (unlikely(queued)) {
1286 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1288 set_current_state(TASK_UNINTERRUPTIBLE);
1289 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1294 * Ahh, all good. It wasn't running, and it wasn't
1295 * runnable, which means that it will never become
1296 * running in the future either. We're all done!
1305 * kick_process - kick a running thread to enter/exit the kernel
1306 * @p: the to-be-kicked thread
1308 * Cause a process which is running on another CPU to enter
1309 * kernel-mode, without any delay. (to get signals handled.)
1311 * NOTE: this function doesn't have to take the runqueue lock,
1312 * because all it wants to ensure is that the remote task enters
1313 * the kernel. If the IPI races and the task has been migrated
1314 * to another CPU then no harm is done and the purpose has been
1317 void kick_process(struct task_struct *p)
1323 if ((cpu != smp_processor_id()) && task_curr(p))
1324 smp_send_reschedule(cpu);
1327 EXPORT_SYMBOL_GPL(kick_process);
1328 #endif /* CONFIG_SMP */
1332 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1334 static int select_fallback_rq(int cpu, struct task_struct *p)
1336 int nid = cpu_to_node(cpu);
1337 const struct cpumask *nodemask = NULL;
1338 enum { cpuset, possible, fail } state = cpuset;
1342 * If the node that the cpu is on has been offlined, cpu_to_node()
1343 * will return -1. There is no cpu on the node, and we should
1344 * select the cpu on the other node.
1347 nodemask = cpumask_of_node(nid);
1349 /* Look for allowed, online CPU in same node. */
1350 for_each_cpu(dest_cpu, nodemask) {
1351 if (!cpu_online(dest_cpu))
1353 if (!cpu_active(dest_cpu))
1355 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1361 /* Any allowed, online CPU? */
1362 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1363 if (!cpu_online(dest_cpu))
1365 if (!cpu_active(dest_cpu))
1372 /* No more Mr. Nice Guy. */
1373 cpuset_cpus_allowed_fallback(p);
1378 do_set_cpus_allowed(p, cpu_possible_mask);
1389 if (state != cpuset) {
1391 * Don't tell them about moving exiting tasks or
1392 * kernel threads (both mm NULL), since they never
1395 if (p->mm && printk_ratelimit()) {
1396 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1397 task_pid_nr(p), p->comm, cpu);
1405 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1408 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1410 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1413 * In order not to call set_task_cpu() on a blocking task we need
1414 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1417 * Since this is common to all placement strategies, this lives here.
1419 * [ this allows ->select_task() to simply return task_cpu(p) and
1420 * not worry about this generic constraint ]
1422 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1424 cpu = select_fallback_rq(task_cpu(p), p);
1429 static void update_avg(u64 *avg, u64 sample)
1431 s64 diff = sample - *avg;
1437 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1439 #ifdef CONFIG_SCHEDSTATS
1440 struct rq *rq = this_rq();
1443 int this_cpu = smp_processor_id();
1445 if (cpu == this_cpu) {
1446 schedstat_inc(rq, ttwu_local);
1447 schedstat_inc(p, se.statistics.nr_wakeups_local);
1449 struct sched_domain *sd;
1451 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1453 for_each_domain(this_cpu, sd) {
1454 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1455 schedstat_inc(sd, ttwu_wake_remote);
1462 if (wake_flags & WF_MIGRATED)
1463 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1465 #endif /* CONFIG_SMP */
1467 schedstat_inc(rq, ttwu_count);
1468 schedstat_inc(p, se.statistics.nr_wakeups);
1470 if (wake_flags & WF_SYNC)
1471 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1473 #endif /* CONFIG_SCHEDSTATS */
1476 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1478 activate_task(rq, p, en_flags);
1479 p->on_rq = TASK_ON_RQ_QUEUED;
1481 /* if a worker is waking up, notify workqueue */
1482 if (p->flags & PF_WQ_WORKER)
1483 wq_worker_waking_up(p, cpu_of(rq));
1487 * Mark the task runnable and perform wakeup-preemption.
1490 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1492 check_preempt_curr(rq, p, wake_flags);
1493 trace_sched_wakeup(p, true);
1495 p->state = TASK_RUNNING;
1497 if (p->sched_class->task_woken)
1498 p->sched_class->task_woken(rq, p);
1500 if (rq->idle_stamp) {
1501 u64 delta = rq_clock(rq) - rq->idle_stamp;
1502 u64 max = 2*rq->max_idle_balance_cost;
1504 update_avg(&rq->avg_idle, delta);
1506 if (rq->avg_idle > max)
1515 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1518 if (p->sched_contributes_to_load)
1519 rq->nr_uninterruptible--;
1522 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1523 ttwu_do_wakeup(rq, p, wake_flags);
1527 * Called in case the task @p isn't fully descheduled from its runqueue,
1528 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1529 * since all we need to do is flip p->state to TASK_RUNNING, since
1530 * the task is still ->on_rq.
1532 static int ttwu_remote(struct task_struct *p, int wake_flags)
1537 rq = __task_rq_lock(p);
1538 if (task_on_rq_queued(p)) {
1539 /* check_preempt_curr() may use rq clock */
1540 update_rq_clock(rq);
1541 ttwu_do_wakeup(rq, p, wake_flags);
1544 __task_rq_unlock(rq);
1550 void sched_ttwu_pending(void)
1552 struct rq *rq = this_rq();
1553 struct llist_node *llist = llist_del_all(&rq->wake_list);
1554 struct task_struct *p;
1555 unsigned long flags;
1560 raw_spin_lock_irqsave(&rq->lock, flags);
1563 p = llist_entry(llist, struct task_struct, wake_entry);
1564 llist = llist_next(llist);
1565 ttwu_do_activate(rq, p, 0);
1568 raw_spin_unlock_irqrestore(&rq->lock, flags);
1571 void scheduler_ipi(void)
1574 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1575 * TIF_NEED_RESCHED remotely (for the first time) will also send
1578 preempt_fold_need_resched();
1580 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1584 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1585 * traditionally all their work was done from the interrupt return
1586 * path. Now that we actually do some work, we need to make sure
1589 * Some archs already do call them, luckily irq_enter/exit nest
1592 * Arguably we should visit all archs and update all handlers,
1593 * however a fair share of IPIs are still resched only so this would
1594 * somewhat pessimize the simple resched case.
1597 sched_ttwu_pending();
1600 * Check if someone kicked us for doing the nohz idle load balance.
1602 if (unlikely(got_nohz_idle_kick())) {
1603 this_rq()->idle_balance = 1;
1604 raise_softirq_irqoff(SCHED_SOFTIRQ);
1609 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1611 struct rq *rq = cpu_rq(cpu);
1613 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1614 if (!set_nr_if_polling(rq->idle))
1615 smp_send_reschedule(cpu);
1617 trace_sched_wake_idle_without_ipi(cpu);
1621 void wake_up_if_idle(int cpu)
1623 struct rq *rq = cpu_rq(cpu);
1624 unsigned long flags;
1626 if (!is_idle_task(rq->curr))
1629 if (set_nr_if_polling(rq->idle)) {
1630 trace_sched_wake_idle_without_ipi(cpu);
1632 raw_spin_lock_irqsave(&rq->lock, flags);
1633 if (is_idle_task(rq->curr))
1634 smp_send_reschedule(cpu);
1635 /* Else cpu is not in idle, do nothing here */
1636 raw_spin_unlock_irqrestore(&rq->lock, flags);
1640 bool cpus_share_cache(int this_cpu, int that_cpu)
1642 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1644 #endif /* CONFIG_SMP */
1646 static void ttwu_queue(struct task_struct *p, int cpu)
1648 struct rq *rq = cpu_rq(cpu);
1650 #if defined(CONFIG_SMP)
1651 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1652 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1653 ttwu_queue_remote(p, cpu);
1658 raw_spin_lock(&rq->lock);
1659 ttwu_do_activate(rq, p, 0);
1660 raw_spin_unlock(&rq->lock);
1664 * try_to_wake_up - wake up a thread
1665 * @p: the thread to be awakened
1666 * @state: the mask of task states that can be woken
1667 * @wake_flags: wake modifier flags (WF_*)
1669 * Put it on the run-queue if it's not already there. The "current"
1670 * thread is always on the run-queue (except when the actual
1671 * re-schedule is in progress), and as such you're allowed to do
1672 * the simpler "current->state = TASK_RUNNING" to mark yourself
1673 * runnable without the overhead of this.
1675 * Return: %true if @p was woken up, %false if it was already running.
1676 * or @state didn't match @p's state.
1679 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1681 unsigned long flags;
1682 int cpu, success = 0;
1685 * If we are going to wake up a thread waiting for CONDITION we
1686 * need to ensure that CONDITION=1 done by the caller can not be
1687 * reordered with p->state check below. This pairs with mb() in
1688 * set_current_state() the waiting thread does.
1690 smp_mb__before_spinlock();
1691 raw_spin_lock_irqsave(&p->pi_lock, flags);
1692 if (!(p->state & state))
1695 success = 1; /* we're going to change ->state */
1698 if (p->on_rq && ttwu_remote(p, wake_flags))
1703 * If the owning (remote) cpu is still in the middle of schedule() with
1704 * this task as prev, wait until its done referencing the task.
1709 * Pairs with the smp_wmb() in finish_lock_switch().
1713 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1714 p->state = TASK_WAKING;
1716 if (p->sched_class->task_waking)
1717 p->sched_class->task_waking(p);
1719 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1720 if (task_cpu(p) != cpu) {
1721 wake_flags |= WF_MIGRATED;
1722 set_task_cpu(p, cpu);
1724 #endif /* CONFIG_SMP */
1728 ttwu_stat(p, cpu, wake_flags);
1730 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1736 * try_to_wake_up_local - try to wake up a local task with rq lock held
1737 * @p: the thread to be awakened
1739 * Put @p on the run-queue if it's not already there. The caller must
1740 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1743 static void try_to_wake_up_local(struct task_struct *p)
1745 struct rq *rq = task_rq(p);
1747 if (WARN_ON_ONCE(rq != this_rq()) ||
1748 WARN_ON_ONCE(p == current))
1751 lockdep_assert_held(&rq->lock);
1753 if (!raw_spin_trylock(&p->pi_lock)) {
1754 raw_spin_unlock(&rq->lock);
1755 raw_spin_lock(&p->pi_lock);
1756 raw_spin_lock(&rq->lock);
1759 if (!(p->state & TASK_NORMAL))
1762 if (!task_on_rq_queued(p))
1763 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1765 ttwu_do_wakeup(rq, p, 0);
1766 ttwu_stat(p, smp_processor_id(), 0);
1768 raw_spin_unlock(&p->pi_lock);
1772 * wake_up_process - Wake up a specific process
1773 * @p: The process to be woken up.
1775 * Attempt to wake up the nominated process and move it to the set of runnable
1778 * Return: 1 if the process was woken up, 0 if it was already running.
1780 * It may be assumed that this function implies a write memory barrier before
1781 * changing the task state if and only if any tasks are woken up.
1783 int wake_up_process(struct task_struct *p)
1785 WARN_ON(task_is_stopped_or_traced(p));
1786 return try_to_wake_up(p, TASK_NORMAL, 0);
1788 EXPORT_SYMBOL(wake_up_process);
1790 int wake_up_state(struct task_struct *p, unsigned int state)
1792 return try_to_wake_up(p, state, 0);
1796 * This function clears the sched_dl_entity static params.
1798 void __dl_clear_params(struct task_struct *p)
1800 struct sched_dl_entity *dl_se = &p->dl;
1802 dl_se->dl_runtime = 0;
1803 dl_se->dl_deadline = 0;
1804 dl_se->dl_period = 0;
1810 * Perform scheduler related setup for a newly forked process p.
1811 * p is forked by current.
1813 * __sched_fork() is basic setup used by init_idle() too:
1815 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
1820 p->se.exec_start = 0;
1821 p->se.sum_exec_runtime = 0;
1822 p->se.prev_sum_exec_runtime = 0;
1823 p->se.nr_migrations = 0;
1825 INIT_LIST_HEAD(&p->se.group_node);
1827 #ifdef CONFIG_SCHEDSTATS
1828 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1831 RB_CLEAR_NODE(&p->dl.rb_node);
1832 hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1833 __dl_clear_params(p);
1835 INIT_LIST_HEAD(&p->rt.run_list);
1837 #ifdef CONFIG_PREEMPT_NOTIFIERS
1838 INIT_HLIST_HEAD(&p->preempt_notifiers);
1841 #ifdef CONFIG_NUMA_BALANCING
1842 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
1843 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
1844 p->mm->numa_scan_seq = 0;
1847 if (clone_flags & CLONE_VM)
1848 p->numa_preferred_nid = current->numa_preferred_nid;
1850 p->numa_preferred_nid = -1;
1852 p->node_stamp = 0ULL;
1853 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
1854 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
1855 p->numa_work.next = &p->numa_work;
1856 p->numa_faults_memory = NULL;
1857 p->numa_faults_buffer_memory = NULL;
1858 p->last_task_numa_placement = 0;
1859 p->last_sum_exec_runtime = 0;
1861 INIT_LIST_HEAD(&p->numa_entry);
1862 p->numa_group = NULL;
1863 #endif /* CONFIG_NUMA_BALANCING */
1866 #ifdef CONFIG_NUMA_BALANCING
1867 #ifdef CONFIG_SCHED_DEBUG
1868 void set_numabalancing_state(bool enabled)
1871 sched_feat_set("NUMA");
1873 sched_feat_set("NO_NUMA");
1876 __read_mostly bool numabalancing_enabled;
1878 void set_numabalancing_state(bool enabled)
1880 numabalancing_enabled = enabled;
1882 #endif /* CONFIG_SCHED_DEBUG */
1884 #ifdef CONFIG_PROC_SYSCTL
1885 int sysctl_numa_balancing(struct ctl_table *table, int write,
1886 void __user *buffer, size_t *lenp, loff_t *ppos)
1890 int state = numabalancing_enabled;
1892 if (write && !capable(CAP_SYS_ADMIN))
1897 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
1901 set_numabalancing_state(state);
1908 * fork()/clone()-time setup:
1910 int sched_fork(unsigned long clone_flags, struct task_struct *p)
1912 unsigned long flags;
1913 int cpu = get_cpu();
1915 __sched_fork(clone_flags, p);
1917 * We mark the process as running here. This guarantees that
1918 * nobody will actually run it, and a signal or other external
1919 * event cannot wake it up and insert it on the runqueue either.
1921 p->state = TASK_RUNNING;
1924 * Make sure we do not leak PI boosting priority to the child.
1926 p->prio = current->normal_prio;
1929 * Revert to default priority/policy on fork if requested.
1931 if (unlikely(p->sched_reset_on_fork)) {
1932 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
1933 p->policy = SCHED_NORMAL;
1934 p->static_prio = NICE_TO_PRIO(0);
1936 } else if (PRIO_TO_NICE(p->static_prio) < 0)
1937 p->static_prio = NICE_TO_PRIO(0);
1939 p->prio = p->normal_prio = __normal_prio(p);
1943 * We don't need the reset flag anymore after the fork. It has
1944 * fulfilled its duty:
1946 p->sched_reset_on_fork = 0;
1949 if (dl_prio(p->prio)) {
1952 } else if (rt_prio(p->prio)) {
1953 p->sched_class = &rt_sched_class;
1955 p->sched_class = &fair_sched_class;
1958 if (p->sched_class->task_fork)
1959 p->sched_class->task_fork(p);
1962 * The child is not yet in the pid-hash so no cgroup attach races,
1963 * and the cgroup is pinned to this child due to cgroup_fork()
1964 * is ran before sched_fork().
1966 * Silence PROVE_RCU.
1968 raw_spin_lock_irqsave(&p->pi_lock, flags);
1969 set_task_cpu(p, cpu);
1970 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1972 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1973 if (likely(sched_info_on()))
1974 memset(&p->sched_info, 0, sizeof(p->sched_info));
1976 #if defined(CONFIG_SMP)
1979 init_task_preempt_count(p);
1981 plist_node_init(&p->pushable_tasks, MAX_PRIO);
1982 RB_CLEAR_NODE(&p->pushable_dl_tasks);
1989 unsigned long to_ratio(u64 period, u64 runtime)
1991 if (runtime == RUNTIME_INF)
1995 * Doing this here saves a lot of checks in all
1996 * the calling paths, and returning zero seems
1997 * safe for them anyway.
2002 return div64_u64(runtime << 20, period);
2006 inline struct dl_bw *dl_bw_of(int i)
2008 rcu_lockdep_assert(rcu_read_lock_sched_held(),
2009 "sched RCU must be held");
2010 return &cpu_rq(i)->rd->dl_bw;
2013 static inline int dl_bw_cpus(int i)
2015 struct root_domain *rd = cpu_rq(i)->rd;
2018 rcu_lockdep_assert(rcu_read_lock_sched_held(),
2019 "sched RCU must be held");
2020 for_each_cpu_and(i, rd->span, cpu_active_mask)
2026 inline struct dl_bw *dl_bw_of(int i)
2028 return &cpu_rq(i)->dl.dl_bw;
2031 static inline int dl_bw_cpus(int i)
2038 void __dl_clear(struct dl_bw *dl_b, u64 tsk_bw)
2040 dl_b->total_bw -= tsk_bw;
2044 void __dl_add(struct dl_bw *dl_b, u64 tsk_bw)
2046 dl_b->total_bw += tsk_bw;
2050 bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
2052 return dl_b->bw != -1 &&
2053 dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
2057 * We must be sure that accepting a new task (or allowing changing the
2058 * parameters of an existing one) is consistent with the bandwidth
2059 * constraints. If yes, this function also accordingly updates the currently
2060 * allocated bandwidth to reflect the new situation.
2062 * This function is called while holding p's rq->lock.
2064 static int dl_overflow(struct task_struct *p, int policy,
2065 const struct sched_attr *attr)
2068 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2069 u64 period = attr->sched_period ?: attr->sched_deadline;
2070 u64 runtime = attr->sched_runtime;
2071 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2074 if (new_bw == p->dl.dl_bw)
2078 * Either if a task, enters, leave, or stays -deadline but changes
2079 * its parameters, we may need to update accordingly the total
2080 * allocated bandwidth of the container.
2082 raw_spin_lock(&dl_b->lock);
2083 cpus = dl_bw_cpus(task_cpu(p));
2084 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2085 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2086 __dl_add(dl_b, new_bw);
2088 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2089 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2090 __dl_clear(dl_b, p->dl.dl_bw);
2091 __dl_add(dl_b, new_bw);
2093 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2094 __dl_clear(dl_b, p->dl.dl_bw);
2097 raw_spin_unlock(&dl_b->lock);
2102 extern void init_dl_bw(struct dl_bw *dl_b);
2105 * wake_up_new_task - wake up a newly created task for the first time.
2107 * This function will do some initial scheduler statistics housekeeping
2108 * that must be done for every newly created context, then puts the task
2109 * on the runqueue and wakes it.
2111 void wake_up_new_task(struct task_struct *p)
2113 unsigned long flags;
2116 raw_spin_lock_irqsave(&p->pi_lock, flags);
2119 * Fork balancing, do it here and not earlier because:
2120 * - cpus_allowed can change in the fork path
2121 * - any previously selected cpu might disappear through hotplug
2123 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2126 /* Initialize new task's runnable average */
2127 init_task_runnable_average(p);
2128 rq = __task_rq_lock(p);
2129 activate_task(rq, p, 0);
2130 p->on_rq = TASK_ON_RQ_QUEUED;
2131 trace_sched_wakeup_new(p, true);
2132 check_preempt_curr(rq, p, WF_FORK);
2134 if (p->sched_class->task_woken)
2135 p->sched_class->task_woken(rq, p);
2137 task_rq_unlock(rq, p, &flags);
2140 #ifdef CONFIG_PREEMPT_NOTIFIERS
2143 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2144 * @notifier: notifier struct to register
2146 void preempt_notifier_register(struct preempt_notifier *notifier)
2148 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2150 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2153 * preempt_notifier_unregister - no longer interested in preemption notifications
2154 * @notifier: notifier struct to unregister
2156 * This is safe to call from within a preemption notifier.
2158 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2160 hlist_del(¬ifier->link);
2162 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2164 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2166 struct preempt_notifier *notifier;
2168 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2169 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2173 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2174 struct task_struct *next)
2176 struct preempt_notifier *notifier;
2178 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2179 notifier->ops->sched_out(notifier, next);
2182 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2184 static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2189 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2190 struct task_struct *next)
2194 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2197 * prepare_task_switch - prepare to switch tasks
2198 * @rq: the runqueue preparing to switch
2199 * @prev: the current task that is being switched out
2200 * @next: the task we are going to switch to.
2202 * This is called with the rq lock held and interrupts off. It must
2203 * be paired with a subsequent finish_task_switch after the context
2206 * prepare_task_switch sets up locking and calls architecture specific
2210 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2211 struct task_struct *next)
2213 trace_sched_switch(prev, next);
2214 sched_info_switch(rq, prev, next);
2215 perf_event_task_sched_out(prev, next);
2216 fire_sched_out_preempt_notifiers(prev, next);
2217 prepare_lock_switch(rq, next);
2218 prepare_arch_switch(next);
2222 * finish_task_switch - clean up after a task-switch
2223 * @rq: runqueue associated with task-switch
2224 * @prev: the thread we just switched away from.
2226 * finish_task_switch must be called after the context switch, paired
2227 * with a prepare_task_switch call before the context switch.
2228 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2229 * and do any other architecture-specific cleanup actions.
2231 * Note that we may have delayed dropping an mm in context_switch(). If
2232 * so, we finish that here outside of the runqueue lock. (Doing it
2233 * with the lock held can cause deadlocks; see schedule() for
2236 static void finish_task_switch(struct rq *rq, struct task_struct *prev)
2237 __releases(rq->lock)
2239 struct mm_struct *mm = rq->prev_mm;
2245 * A task struct has one reference for the use as "current".
2246 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2247 * schedule one last time. The schedule call will never return, and
2248 * the scheduled task must drop that reference.
2249 * The test for TASK_DEAD must occur while the runqueue locks are
2250 * still held, otherwise prev could be scheduled on another cpu, die
2251 * there before we look at prev->state, and then the reference would
2253 * Manfred Spraul <manfred@colorfullife.com>
2255 prev_state = prev->state;
2256 vtime_task_switch(prev);
2257 finish_arch_switch(prev);
2258 perf_event_task_sched_in(prev, current);
2259 finish_lock_switch(rq, prev);
2260 finish_arch_post_lock_switch();
2262 fire_sched_in_preempt_notifiers(current);
2265 if (unlikely(prev_state == TASK_DEAD)) {
2266 if (prev->sched_class->task_dead)
2267 prev->sched_class->task_dead(prev);
2270 * Remove function-return probe instances associated with this
2271 * task and put them back on the free list.
2273 kprobe_flush_task(prev);
2274 put_task_struct(prev);
2277 tick_nohz_task_switch(current);
2282 /* rq->lock is NOT held, but preemption is disabled */
2283 static inline void post_schedule(struct rq *rq)
2285 if (rq->post_schedule) {
2286 unsigned long flags;
2288 raw_spin_lock_irqsave(&rq->lock, flags);
2289 if (rq->curr->sched_class->post_schedule)
2290 rq->curr->sched_class->post_schedule(rq);
2291 raw_spin_unlock_irqrestore(&rq->lock, flags);
2293 rq->post_schedule = 0;
2299 static inline void post_schedule(struct rq *rq)
2306 * schedule_tail - first thing a freshly forked thread must call.
2307 * @prev: the thread we just switched away from.
2309 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2310 __releases(rq->lock)
2312 struct rq *rq = this_rq();
2314 finish_task_switch(rq, prev);
2317 * FIXME: do we need to worry about rq being invalidated by the
2322 if (current->set_child_tid)
2323 put_user(task_pid_vnr(current), current->set_child_tid);
2327 * context_switch - switch to the new MM and the new
2328 * thread's register state.
2331 context_switch(struct rq *rq, struct task_struct *prev,
2332 struct task_struct *next)
2334 struct mm_struct *mm, *oldmm;
2336 prepare_task_switch(rq, prev, next);
2339 oldmm = prev->active_mm;
2341 * For paravirt, this is coupled with an exit in switch_to to
2342 * combine the page table reload and the switch backend into
2345 arch_start_context_switch(prev);
2348 next->active_mm = oldmm;
2349 atomic_inc(&oldmm->mm_count);
2350 enter_lazy_tlb(oldmm, next);
2352 switch_mm(oldmm, mm, next);
2355 prev->active_mm = NULL;
2356 rq->prev_mm = oldmm;
2359 * Since the runqueue lock will be released by the next
2360 * task (which is an invalid locking op but in the case
2361 * of the scheduler it's an obvious special-case), so we
2362 * do an early lockdep release here:
2364 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2366 context_tracking_task_switch(prev, next);
2367 /* Here we just switch the register state and the stack. */
2368 switch_to(prev, next, prev);
2372 * this_rq must be evaluated again because prev may have moved
2373 * CPUs since it called schedule(), thus the 'rq' on its stack
2374 * frame will be invalid.
2376 finish_task_switch(this_rq(), prev);
2380 * nr_running and nr_context_switches:
2382 * externally visible scheduler statistics: current number of runnable
2383 * threads, total number of context switches performed since bootup.
2385 unsigned long nr_running(void)
2387 unsigned long i, sum = 0;
2389 for_each_online_cpu(i)
2390 sum += cpu_rq(i)->nr_running;
2396 * Check if only the current task is running on the cpu.
2398 bool single_task_running(void)
2400 if (cpu_rq(smp_processor_id())->nr_running == 1)
2405 EXPORT_SYMBOL(single_task_running);
2407 unsigned long long nr_context_switches(void)
2410 unsigned long long sum = 0;
2412 for_each_possible_cpu(i)
2413 sum += cpu_rq(i)->nr_switches;
2418 unsigned long nr_iowait(void)
2420 unsigned long i, sum = 0;
2422 for_each_possible_cpu(i)
2423 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2428 unsigned long nr_iowait_cpu(int cpu)
2430 struct rq *this = cpu_rq(cpu);
2431 return atomic_read(&this->nr_iowait);
2434 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2436 struct rq *this = this_rq();
2437 *nr_waiters = atomic_read(&this->nr_iowait);
2438 *load = this->cpu_load[0];
2444 * sched_exec - execve() is a valuable balancing opportunity, because at
2445 * this point the task has the smallest effective memory and cache footprint.
2447 void sched_exec(void)
2449 struct task_struct *p = current;
2450 unsigned long flags;
2453 raw_spin_lock_irqsave(&p->pi_lock, flags);
2454 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2455 if (dest_cpu == smp_processor_id())
2458 if (likely(cpu_active(dest_cpu))) {
2459 struct migration_arg arg = { p, dest_cpu };
2461 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2462 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2466 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2471 DEFINE_PER_CPU(struct kernel_stat, kstat);
2472 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2474 EXPORT_PER_CPU_SYMBOL(kstat);
2475 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2478 * Return any ns on the sched_clock that have not yet been accounted in
2479 * @p in case that task is currently running.
2481 * Called with task_rq_lock() held on @rq.
2483 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2488 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2489 * project cycles that may never be accounted to this
2490 * thread, breaking clock_gettime().
2492 if (task_current(rq, p) && task_on_rq_queued(p)) {
2493 update_rq_clock(rq);
2494 ns = rq_clock_task(rq) - p->se.exec_start;
2502 unsigned long long task_delta_exec(struct task_struct *p)
2504 unsigned long flags;
2508 rq = task_rq_lock(p, &flags);
2509 ns = do_task_delta_exec(p, rq);
2510 task_rq_unlock(rq, p, &flags);
2516 * Return accounted runtime for the task.
2517 * In case the task is currently running, return the runtime plus current's
2518 * pending runtime that have not been accounted yet.
2520 unsigned long long task_sched_runtime(struct task_struct *p)
2522 unsigned long flags;
2526 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2528 * 64-bit doesn't need locks to atomically read a 64bit value.
2529 * So we have a optimization chance when the task's delta_exec is 0.
2530 * Reading ->on_cpu is racy, but this is ok.
2532 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2533 * If we race with it entering cpu, unaccounted time is 0. This is
2534 * indistinguishable from the read occurring a few cycles earlier.
2535 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2536 * been accounted, so we're correct here as well.
2538 if (!p->on_cpu || !task_on_rq_queued(p))
2539 return p->se.sum_exec_runtime;
2542 rq = task_rq_lock(p, &flags);
2543 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2544 task_rq_unlock(rq, p, &flags);
2550 * This function gets called by the timer code, with HZ frequency.
2551 * We call it with interrupts disabled.
2553 void scheduler_tick(void)
2555 int cpu = smp_processor_id();
2556 struct rq *rq = cpu_rq(cpu);
2557 struct task_struct *curr = rq->curr;
2561 raw_spin_lock(&rq->lock);
2562 update_rq_clock(rq);
2563 curr->sched_class->task_tick(rq, curr, 0);
2564 update_cpu_load_active(rq);
2565 raw_spin_unlock(&rq->lock);
2567 perf_event_task_tick();
2570 rq->idle_balance = idle_cpu(cpu);
2571 trigger_load_balance(rq);
2573 rq_last_tick_reset(rq);
2576 #ifdef CONFIG_NO_HZ_FULL
2578 * scheduler_tick_max_deferment
2580 * Keep at least one tick per second when a single
2581 * active task is running because the scheduler doesn't
2582 * yet completely support full dynticks environment.
2584 * This makes sure that uptime, CFS vruntime, load
2585 * balancing, etc... continue to move forward, even
2586 * with a very low granularity.
2588 * Return: Maximum deferment in nanoseconds.
2590 u64 scheduler_tick_max_deferment(void)
2592 struct rq *rq = this_rq();
2593 unsigned long next, now = ACCESS_ONCE(jiffies);
2595 next = rq->last_sched_tick + HZ;
2597 if (time_before_eq(next, now))
2600 return jiffies_to_nsecs(next - now);
2604 notrace unsigned long get_parent_ip(unsigned long addr)
2606 if (in_lock_functions(addr)) {
2607 addr = CALLER_ADDR2;
2608 if (in_lock_functions(addr))
2609 addr = CALLER_ADDR3;
2614 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2615 defined(CONFIG_PREEMPT_TRACER))
2617 void preempt_count_add(int val)
2619 #ifdef CONFIG_DEBUG_PREEMPT
2623 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2626 __preempt_count_add(val);
2627 #ifdef CONFIG_DEBUG_PREEMPT
2629 * Spinlock count overflowing soon?
2631 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2634 if (preempt_count() == val) {
2635 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2636 #ifdef CONFIG_DEBUG_PREEMPT
2637 current->preempt_disable_ip = ip;
2639 trace_preempt_off(CALLER_ADDR0, ip);
2642 EXPORT_SYMBOL(preempt_count_add);
2643 NOKPROBE_SYMBOL(preempt_count_add);
2645 void preempt_count_sub(int val)
2647 #ifdef CONFIG_DEBUG_PREEMPT
2651 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2654 * Is the spinlock portion underflowing?
2656 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2657 !(preempt_count() & PREEMPT_MASK)))
2661 if (preempt_count() == val)
2662 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2663 __preempt_count_sub(val);
2665 EXPORT_SYMBOL(preempt_count_sub);
2666 NOKPROBE_SYMBOL(preempt_count_sub);
2671 * Print scheduling while atomic bug:
2673 static noinline void __schedule_bug(struct task_struct *prev)
2675 if (oops_in_progress)
2678 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2679 prev->comm, prev->pid, preempt_count());
2681 debug_show_held_locks(prev);
2683 if (irqs_disabled())
2684 print_irqtrace_events(prev);
2685 #ifdef CONFIG_DEBUG_PREEMPT
2686 if (in_atomic_preempt_off()) {
2687 pr_err("Preemption disabled at:");
2688 print_ip_sym(current->preempt_disable_ip);
2693 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2697 * Various schedule()-time debugging checks and statistics:
2699 static inline void schedule_debug(struct task_struct *prev)
2701 #ifdef CONFIG_SCHED_STACK_END_CHECK
2702 BUG_ON(unlikely(task_stack_end_corrupted(prev)));
2705 * Test if we are atomic. Since do_exit() needs to call into
2706 * schedule() atomically, we ignore that path. Otherwise whine
2707 * if we are scheduling when we should not.
2709 if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
2710 __schedule_bug(prev);
2713 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2715 schedstat_inc(this_rq(), sched_count);
2719 * Pick up the highest-prio task:
2721 static inline struct task_struct *
2722 pick_next_task(struct rq *rq, struct task_struct *prev)
2724 const struct sched_class *class = &fair_sched_class;
2725 struct task_struct *p;
2728 * Optimization: we know that if all tasks are in
2729 * the fair class we can call that function directly:
2731 if (likely(prev->sched_class == class &&
2732 rq->nr_running == rq->cfs.h_nr_running)) {
2733 p = fair_sched_class.pick_next_task(rq, prev);
2734 if (unlikely(p == RETRY_TASK))
2737 /* assumes fair_sched_class->next == idle_sched_class */
2739 p = idle_sched_class.pick_next_task(rq, prev);
2745 for_each_class(class) {
2746 p = class->pick_next_task(rq, prev);
2748 if (unlikely(p == RETRY_TASK))
2754 BUG(); /* the idle class will always have a runnable task */
2758 * __schedule() is the main scheduler function.
2760 * The main means of driving the scheduler and thus entering this function are:
2762 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2764 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2765 * paths. For example, see arch/x86/entry_64.S.
2767 * To drive preemption between tasks, the scheduler sets the flag in timer
2768 * interrupt handler scheduler_tick().
2770 * 3. Wakeups don't really cause entry into schedule(). They add a
2771 * task to the run-queue and that's it.
2773 * Now, if the new task added to the run-queue preempts the current
2774 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2775 * called on the nearest possible occasion:
2777 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2779 * - in syscall or exception context, at the next outmost
2780 * preempt_enable(). (this might be as soon as the wake_up()'s
2783 * - in IRQ context, return from interrupt-handler to
2784 * preemptible context
2786 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2789 * - cond_resched() call
2790 * - explicit schedule() call
2791 * - return from syscall or exception to user-space
2792 * - return from interrupt-handler to user-space
2794 static void __sched __schedule(void)
2796 struct task_struct *prev, *next;
2797 unsigned long *switch_count;
2803 cpu = smp_processor_id();
2805 rcu_note_context_switch(cpu);
2808 schedule_debug(prev);
2810 if (sched_feat(HRTICK))
2814 * Make sure that signal_pending_state()->signal_pending() below
2815 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2816 * done by the caller to avoid the race with signal_wake_up().
2818 smp_mb__before_spinlock();
2819 raw_spin_lock_irq(&rq->lock);
2821 switch_count = &prev->nivcsw;
2822 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2823 if (unlikely(signal_pending_state(prev->state, prev))) {
2824 prev->state = TASK_RUNNING;
2826 deactivate_task(rq, prev, DEQUEUE_SLEEP);
2830 * If a worker went to sleep, notify and ask workqueue
2831 * whether it wants to wake up a task to maintain
2834 if (prev->flags & PF_WQ_WORKER) {
2835 struct task_struct *to_wakeup;
2837 to_wakeup = wq_worker_sleeping(prev, cpu);
2839 try_to_wake_up_local(to_wakeup);
2842 switch_count = &prev->nvcsw;
2845 if (task_on_rq_queued(prev) || rq->skip_clock_update < 0)
2846 update_rq_clock(rq);
2848 next = pick_next_task(rq, prev);
2849 clear_tsk_need_resched(prev);
2850 clear_preempt_need_resched();
2851 rq->skip_clock_update = 0;
2853 if (likely(prev != next)) {
2858 context_switch(rq, prev, next); /* unlocks the rq */
2860 * The context switch have flipped the stack from under us
2861 * and restored the local variables which were saved when
2862 * this task called schedule() in the past. prev == current
2863 * is still correct, but it can be moved to another cpu/rq.
2865 cpu = smp_processor_id();
2868 raw_spin_unlock_irq(&rq->lock);
2872 sched_preempt_enable_no_resched();
2877 static inline void sched_submit_work(struct task_struct *tsk)
2879 if (!tsk->state || tsk_is_pi_blocked(tsk))
2882 * If we are going to sleep and we have plugged IO queued,
2883 * make sure to submit it to avoid deadlocks.
2885 if (blk_needs_flush_plug(tsk))
2886 blk_schedule_flush_plug(tsk);
2889 asmlinkage __visible void __sched schedule(void)
2891 struct task_struct *tsk = current;
2893 sched_submit_work(tsk);
2896 EXPORT_SYMBOL(schedule);
2898 #ifdef CONFIG_CONTEXT_TRACKING
2899 asmlinkage __visible void __sched schedule_user(void)
2902 * If we come here after a random call to set_need_resched(),
2903 * or we have been woken up remotely but the IPI has not yet arrived,
2904 * we haven't yet exited the RCU idle mode. Do it here manually until
2905 * we find a better solution.
2914 * schedule_preempt_disabled - called with preemption disabled
2916 * Returns with preemption disabled. Note: preempt_count must be 1
2918 void __sched schedule_preempt_disabled(void)
2920 sched_preempt_enable_no_resched();
2925 #ifdef CONFIG_PREEMPT
2927 * this is the entry point to schedule() from in-kernel preemption
2928 * off of preempt_enable. Kernel preemptions off return from interrupt
2929 * occur there and call schedule directly.
2931 asmlinkage __visible void __sched notrace preempt_schedule(void)
2934 * If there is a non-zero preempt_count or interrupts are disabled,
2935 * we do not want to preempt the current task. Just return..
2937 if (likely(!preemptible()))
2941 __preempt_count_add(PREEMPT_ACTIVE);
2943 __preempt_count_sub(PREEMPT_ACTIVE);
2946 * Check again in case we missed a preemption opportunity
2947 * between schedule and now.
2950 } while (need_resched());
2952 NOKPROBE_SYMBOL(preempt_schedule);
2953 EXPORT_SYMBOL(preempt_schedule);
2954 #endif /* CONFIG_PREEMPT */
2957 * this is the entry point to schedule() from kernel preemption
2958 * off of irq context.
2959 * Note, that this is called and return with irqs disabled. This will
2960 * protect us against recursive calling from irq.
2962 asmlinkage __visible void __sched preempt_schedule_irq(void)
2964 enum ctx_state prev_state;
2966 /* Catch callers which need to be fixed */
2967 BUG_ON(preempt_count() || !irqs_disabled());
2969 prev_state = exception_enter();
2972 __preempt_count_add(PREEMPT_ACTIVE);
2975 local_irq_disable();
2976 __preempt_count_sub(PREEMPT_ACTIVE);
2979 * Check again in case we missed a preemption opportunity
2980 * between schedule and now.
2983 } while (need_resched());
2985 exception_exit(prev_state);
2988 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
2991 return try_to_wake_up(curr->private, mode, wake_flags);
2993 EXPORT_SYMBOL(default_wake_function);
2995 #ifdef CONFIG_RT_MUTEXES
2998 * rt_mutex_setprio - set the current priority of a task
3000 * @prio: prio value (kernel-internal form)
3002 * This function changes the 'effective' priority of a task. It does
3003 * not touch ->normal_prio like __setscheduler().
3005 * Used by the rt_mutex code to implement priority inheritance
3006 * logic. Call site only calls if the priority of the task changed.
3008 void rt_mutex_setprio(struct task_struct *p, int prio)
3010 int oldprio, queued, running, enqueue_flag = 0;
3012 const struct sched_class *prev_class;
3014 BUG_ON(prio > MAX_PRIO);
3016 rq = __task_rq_lock(p);
3019 * Idle task boosting is a nono in general. There is one
3020 * exception, when PREEMPT_RT and NOHZ is active:
3022 * The idle task calls get_next_timer_interrupt() and holds
3023 * the timer wheel base->lock on the CPU and another CPU wants
3024 * to access the timer (probably to cancel it). We can safely
3025 * ignore the boosting request, as the idle CPU runs this code
3026 * with interrupts disabled and will complete the lock
3027 * protected section without being interrupted. So there is no
3028 * real need to boost.
3030 if (unlikely(p == rq->idle)) {
3031 WARN_ON(p != rq->curr);
3032 WARN_ON(p->pi_blocked_on);
3036 trace_sched_pi_setprio(p, prio);
3038 prev_class = p->sched_class;
3039 queued = task_on_rq_queued(p);
3040 running = task_current(rq, p);
3042 dequeue_task(rq, p, 0);
3044 put_prev_task(rq, p);
3047 * Boosting condition are:
3048 * 1. -rt task is running and holds mutex A
3049 * --> -dl task blocks on mutex A
3051 * 2. -dl task is running and holds mutex A
3052 * --> -dl task blocks on mutex A and could preempt the
3055 if (dl_prio(prio)) {
3056 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3057 if (!dl_prio(p->normal_prio) ||
3058 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3059 p->dl.dl_boosted = 1;
3060 p->dl.dl_throttled = 0;
3061 enqueue_flag = ENQUEUE_REPLENISH;
3063 p->dl.dl_boosted = 0;
3064 p->sched_class = &dl_sched_class;
3065 } else if (rt_prio(prio)) {
3066 if (dl_prio(oldprio))
3067 p->dl.dl_boosted = 0;
3069 enqueue_flag = ENQUEUE_HEAD;
3070 p->sched_class = &rt_sched_class;
3072 if (dl_prio(oldprio))
3073 p->dl.dl_boosted = 0;
3074 p->sched_class = &fair_sched_class;
3080 p->sched_class->set_curr_task(rq);
3082 enqueue_task(rq, p, enqueue_flag);
3084 check_class_changed(rq, p, prev_class, oldprio);
3086 __task_rq_unlock(rq);
3090 void set_user_nice(struct task_struct *p, long nice)
3092 int old_prio, delta, queued;
3093 unsigned long flags;
3096 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3099 * We have to be careful, if called from sys_setpriority(),
3100 * the task might be in the middle of scheduling on another CPU.
3102 rq = task_rq_lock(p, &flags);
3104 * The RT priorities are set via sched_setscheduler(), but we still
3105 * allow the 'normal' nice value to be set - but as expected
3106 * it wont have any effect on scheduling until the task is
3107 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3109 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3110 p->static_prio = NICE_TO_PRIO(nice);
3113 queued = task_on_rq_queued(p);
3115 dequeue_task(rq, p, 0);
3117 p->static_prio = NICE_TO_PRIO(nice);
3120 p->prio = effective_prio(p);
3121 delta = p->prio - old_prio;
3124 enqueue_task(rq, p, 0);
3126 * If the task increased its priority or is running and
3127 * lowered its priority, then reschedule its CPU:
3129 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3133 task_rq_unlock(rq, p, &flags);
3135 EXPORT_SYMBOL(set_user_nice);
3138 * can_nice - check if a task can reduce its nice value
3142 int can_nice(const struct task_struct *p, const int nice)
3144 /* convert nice value [19,-20] to rlimit style value [1,40] */
3145 int nice_rlim = nice_to_rlimit(nice);
3147 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3148 capable(CAP_SYS_NICE));
3151 #ifdef __ARCH_WANT_SYS_NICE
3154 * sys_nice - change the priority of the current process.
3155 * @increment: priority increment
3157 * sys_setpriority is a more generic, but much slower function that
3158 * does similar things.
3160 SYSCALL_DEFINE1(nice, int, increment)
3165 * Setpriority might change our priority at the same moment.
3166 * We don't have to worry. Conceptually one call occurs first
3167 * and we have a single winner.
3169 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3170 nice = task_nice(current) + increment;
3172 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3173 if (increment < 0 && !can_nice(current, nice))
3176 retval = security_task_setnice(current, nice);
3180 set_user_nice(current, nice);
3187 * task_prio - return the priority value of a given task.
3188 * @p: the task in question.
3190 * Return: The priority value as seen by users in /proc.
3191 * RT tasks are offset by -200. Normal tasks are centered
3192 * around 0, value goes from -16 to +15.
3194 int task_prio(const struct task_struct *p)
3196 return p->prio - MAX_RT_PRIO;
3200 * idle_cpu - is a given cpu idle currently?
3201 * @cpu: the processor in question.
3203 * Return: 1 if the CPU is currently idle. 0 otherwise.
3205 int idle_cpu(int cpu)
3207 struct rq *rq = cpu_rq(cpu);
3209 if (rq->curr != rq->idle)
3216 if (!llist_empty(&rq->wake_list))
3224 * idle_task - return the idle task for a given cpu.
3225 * @cpu: the processor in question.
3227 * Return: The idle task for the cpu @cpu.
3229 struct task_struct *idle_task(int cpu)
3231 return cpu_rq(cpu)->idle;
3235 * find_process_by_pid - find a process with a matching PID value.
3236 * @pid: the pid in question.
3238 * The task of @pid, if found. %NULL otherwise.
3240 static struct task_struct *find_process_by_pid(pid_t pid)
3242 return pid ? find_task_by_vpid(pid) : current;
3246 * This function initializes the sched_dl_entity of a newly becoming
3247 * SCHED_DEADLINE task.
3249 * Only the static values are considered here, the actual runtime and the
3250 * absolute deadline will be properly calculated when the task is enqueued
3251 * for the first time with its new policy.
3254 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3256 struct sched_dl_entity *dl_se = &p->dl;
3258 init_dl_task_timer(dl_se);
3259 dl_se->dl_runtime = attr->sched_runtime;
3260 dl_se->dl_deadline = attr->sched_deadline;
3261 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3262 dl_se->flags = attr->sched_flags;
3263 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3264 dl_se->dl_throttled = 0;
3266 dl_se->dl_yielded = 0;
3270 * sched_setparam() passes in -1 for its policy, to let the functions
3271 * it calls know not to change it.
3273 #define SETPARAM_POLICY -1
3275 static void __setscheduler_params(struct task_struct *p,
3276 const struct sched_attr *attr)
3278 int policy = attr->sched_policy;
3280 if (policy == SETPARAM_POLICY)
3285 if (dl_policy(policy))
3286 __setparam_dl(p, attr);
3287 else if (fair_policy(policy))
3288 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3291 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3292 * !rt_policy. Always setting this ensures that things like
3293 * getparam()/getattr() don't report silly values for !rt tasks.
3295 p->rt_priority = attr->sched_priority;
3296 p->normal_prio = normal_prio(p);
3300 /* Actually do priority change: must hold pi & rq lock. */
3301 static void __setscheduler(struct rq *rq, struct task_struct *p,
3302 const struct sched_attr *attr)
3304 __setscheduler_params(p, attr);
3307 * If we get here, there was no pi waiters boosting the
3308 * task. It is safe to use the normal prio.
3310 p->prio = normal_prio(p);
3312 if (dl_prio(p->prio))
3313 p->sched_class = &dl_sched_class;
3314 else if (rt_prio(p->prio))
3315 p->sched_class = &rt_sched_class;
3317 p->sched_class = &fair_sched_class;
3321 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3323 struct sched_dl_entity *dl_se = &p->dl;
3325 attr->sched_priority = p->rt_priority;
3326 attr->sched_runtime = dl_se->dl_runtime;
3327 attr->sched_deadline = dl_se->dl_deadline;
3328 attr->sched_period = dl_se->dl_period;
3329 attr->sched_flags = dl_se->flags;
3333 * This function validates the new parameters of a -deadline task.
3334 * We ask for the deadline not being zero, and greater or equal
3335 * than the runtime, as well as the period of being zero or
3336 * greater than deadline. Furthermore, we have to be sure that
3337 * user parameters are above the internal resolution of 1us (we
3338 * check sched_runtime only since it is always the smaller one) and
3339 * below 2^63 ns (we have to check both sched_deadline and
3340 * sched_period, as the latter can be zero).
3343 __checkparam_dl(const struct sched_attr *attr)
3346 if (attr->sched_deadline == 0)
3350 * Since we truncate DL_SCALE bits, make sure we're at least
3353 if (attr->sched_runtime < (1ULL << DL_SCALE))
3357 * Since we use the MSB for wrap-around and sign issues, make
3358 * sure it's not set (mind that period can be equal to zero).
3360 if (attr->sched_deadline & (1ULL << 63) ||
3361 attr->sched_period & (1ULL << 63))
3364 /* runtime <= deadline <= period (if period != 0) */
3365 if ((attr->sched_period != 0 &&
3366 attr->sched_period < attr->sched_deadline) ||
3367 attr->sched_deadline < attr->sched_runtime)
3374 * check the target process has a UID that matches the current process's
3376 static bool check_same_owner(struct task_struct *p)
3378 const struct cred *cred = current_cred(), *pcred;
3382 pcred = __task_cred(p);
3383 match = (uid_eq(cred->euid, pcred->euid) ||
3384 uid_eq(cred->euid, pcred->uid));
3389 static int __sched_setscheduler(struct task_struct *p,
3390 const struct sched_attr *attr,
3393 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3394 MAX_RT_PRIO - 1 - attr->sched_priority;
3395 int retval, oldprio, oldpolicy = -1, queued, running;
3396 int policy = attr->sched_policy;
3397 unsigned long flags;
3398 const struct sched_class *prev_class;
3402 /* may grab non-irq protected spin_locks */
3403 BUG_ON(in_interrupt());
3405 /* double check policy once rq lock held */
3407 reset_on_fork = p->sched_reset_on_fork;
3408 policy = oldpolicy = p->policy;
3410 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3412 if (policy != SCHED_DEADLINE &&
3413 policy != SCHED_FIFO && policy != SCHED_RR &&
3414 policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3415 policy != SCHED_IDLE)
3419 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3423 * Valid priorities for SCHED_FIFO and SCHED_RR are
3424 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3425 * SCHED_BATCH and SCHED_IDLE is 0.
3427 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3428 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3430 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3431 (rt_policy(policy) != (attr->sched_priority != 0)))
3435 * Allow unprivileged RT tasks to decrease priority:
3437 if (user && !capable(CAP_SYS_NICE)) {
3438 if (fair_policy(policy)) {
3439 if (attr->sched_nice < task_nice(p) &&
3440 !can_nice(p, attr->sched_nice))
3444 if (rt_policy(policy)) {
3445 unsigned long rlim_rtprio =
3446 task_rlimit(p, RLIMIT_RTPRIO);
3448 /* can't set/change the rt policy */
3449 if (policy != p->policy && !rlim_rtprio)
3452 /* can't increase priority */
3453 if (attr->sched_priority > p->rt_priority &&
3454 attr->sched_priority > rlim_rtprio)
3459 * Can't set/change SCHED_DEADLINE policy at all for now
3460 * (safest behavior); in the future we would like to allow
3461 * unprivileged DL tasks to increase their relative deadline
3462 * or reduce their runtime (both ways reducing utilization)
3464 if (dl_policy(policy))
3468 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3469 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3471 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3472 if (!can_nice(p, task_nice(p)))
3476 /* can't change other user's priorities */
3477 if (!check_same_owner(p))
3480 /* Normal users shall not reset the sched_reset_on_fork flag */
3481 if (p->sched_reset_on_fork && !reset_on_fork)
3486 retval = security_task_setscheduler(p);
3492 * make sure no PI-waiters arrive (or leave) while we are
3493 * changing the priority of the task:
3495 * To be able to change p->policy safely, the appropriate
3496 * runqueue lock must be held.
3498 rq = task_rq_lock(p, &flags);
3501 * Changing the policy of the stop threads its a very bad idea
3503 if (p == rq->stop) {
3504 task_rq_unlock(rq, p, &flags);
3509 * If not changing anything there's no need to proceed further,
3510 * but store a possible modification of reset_on_fork.
3512 if (unlikely(policy == p->policy)) {
3513 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3515 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3517 if (dl_policy(policy))
3520 p->sched_reset_on_fork = reset_on_fork;
3521 task_rq_unlock(rq, p, &flags);
3527 #ifdef CONFIG_RT_GROUP_SCHED
3529 * Do not allow realtime tasks into groups that have no runtime
3532 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3533 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3534 !task_group_is_autogroup(task_group(p))) {
3535 task_rq_unlock(rq, p, &flags);
3540 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3541 cpumask_t *span = rq->rd->span;
3544 * Don't allow tasks with an affinity mask smaller than
3545 * the entire root_domain to become SCHED_DEADLINE. We
3546 * will also fail if there's no bandwidth available.
3548 if (!cpumask_subset(span, &p->cpus_allowed) ||
3549 rq->rd->dl_bw.bw == 0) {
3550 task_rq_unlock(rq, p, &flags);
3557 /* recheck policy now with rq lock held */
3558 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3559 policy = oldpolicy = -1;
3560 task_rq_unlock(rq, p, &flags);
3565 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3566 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3569 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3570 task_rq_unlock(rq, p, &flags);
3574 p->sched_reset_on_fork = reset_on_fork;
3578 * Special case for priority boosted tasks.
3580 * If the new priority is lower or equal (user space view)
3581 * than the current (boosted) priority, we just store the new
3582 * normal parameters and do not touch the scheduler class and
3583 * the runqueue. This will be done when the task deboost
3586 if (rt_mutex_check_prio(p, newprio)) {
3587 __setscheduler_params(p, attr);
3588 task_rq_unlock(rq, p, &flags);
3592 queued = task_on_rq_queued(p);
3593 running = task_current(rq, p);
3595 dequeue_task(rq, p, 0);
3597 put_prev_task(rq, p);
3599 prev_class = p->sched_class;
3600 __setscheduler(rq, p, attr);
3603 p->sched_class->set_curr_task(rq);
3606 * We enqueue to tail when the priority of a task is
3607 * increased (user space view).
3609 enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
3612 check_class_changed(rq, p, prev_class, oldprio);
3613 task_rq_unlock(rq, p, &flags);
3615 rt_mutex_adjust_pi(p);
3620 static int _sched_setscheduler(struct task_struct *p, int policy,
3621 const struct sched_param *param, bool check)
3623 struct sched_attr attr = {
3624 .sched_policy = policy,
3625 .sched_priority = param->sched_priority,
3626 .sched_nice = PRIO_TO_NICE(p->static_prio),
3629 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
3630 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
3631 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3632 policy &= ~SCHED_RESET_ON_FORK;
3633 attr.sched_policy = policy;
3636 return __sched_setscheduler(p, &attr, check);
3639 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3640 * @p: the task in question.
3641 * @policy: new policy.
3642 * @param: structure containing the new RT priority.
3644 * Return: 0 on success. An error code otherwise.
3646 * NOTE that the task may be already dead.
3648 int sched_setscheduler(struct task_struct *p, int policy,
3649 const struct sched_param *param)
3651 return _sched_setscheduler(p, policy, param, true);
3653 EXPORT_SYMBOL_GPL(sched_setscheduler);
3655 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
3657 return __sched_setscheduler(p, attr, true);
3659 EXPORT_SYMBOL_GPL(sched_setattr);
3662 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3663 * @p: the task in question.
3664 * @policy: new policy.
3665 * @param: structure containing the new RT priority.
3667 * Just like sched_setscheduler, only don't bother checking if the
3668 * current context has permission. For example, this is needed in
3669 * stop_machine(): we create temporary high priority worker threads,
3670 * but our caller might not have that capability.
3672 * Return: 0 on success. An error code otherwise.
3674 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3675 const struct sched_param *param)
3677 return _sched_setscheduler(p, policy, param, false);
3681 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3683 struct sched_param lparam;
3684 struct task_struct *p;
3687 if (!param || pid < 0)
3689 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3694 p = find_process_by_pid(pid);
3696 retval = sched_setscheduler(p, policy, &lparam);
3703 * Mimics kernel/events/core.c perf_copy_attr().
3705 static int sched_copy_attr(struct sched_attr __user *uattr,
3706 struct sched_attr *attr)
3711 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
3715 * zero the full structure, so that a short copy will be nice.
3717 memset(attr, 0, sizeof(*attr));
3719 ret = get_user(size, &uattr->size);
3723 if (size > PAGE_SIZE) /* silly large */
3726 if (!size) /* abi compat */
3727 size = SCHED_ATTR_SIZE_VER0;
3729 if (size < SCHED_ATTR_SIZE_VER0)
3733 * If we're handed a bigger struct than we know of,
3734 * ensure all the unknown bits are 0 - i.e. new
3735 * user-space does not rely on any kernel feature
3736 * extensions we dont know about yet.
3738 if (size > sizeof(*attr)) {
3739 unsigned char __user *addr;
3740 unsigned char __user *end;
3743 addr = (void __user *)uattr + sizeof(*attr);
3744 end = (void __user *)uattr + size;
3746 for (; addr < end; addr++) {
3747 ret = get_user(val, addr);
3753 size = sizeof(*attr);
3756 ret = copy_from_user(attr, uattr, size);
3761 * XXX: do we want to be lenient like existing syscalls; or do we want
3762 * to be strict and return an error on out-of-bounds values?
3764 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
3769 put_user(sizeof(*attr), &uattr->size);
3774 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3775 * @pid: the pid in question.
3776 * @policy: new policy.
3777 * @param: structure containing the new RT priority.
3779 * Return: 0 on success. An error code otherwise.
3781 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3782 struct sched_param __user *, param)
3784 /* negative values for policy are not valid */
3788 return do_sched_setscheduler(pid, policy, param);
3792 * sys_sched_setparam - set/change the RT priority of a thread
3793 * @pid: the pid in question.
3794 * @param: structure containing the new RT priority.
3796 * Return: 0 on success. An error code otherwise.
3798 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3800 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
3804 * sys_sched_setattr - same as above, but with extended sched_attr
3805 * @pid: the pid in question.
3806 * @uattr: structure containing the extended parameters.
3807 * @flags: for future extension.
3809 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
3810 unsigned int, flags)
3812 struct sched_attr attr;
3813 struct task_struct *p;
3816 if (!uattr || pid < 0 || flags)
3819 retval = sched_copy_attr(uattr, &attr);
3823 if ((int)attr.sched_policy < 0)
3828 p = find_process_by_pid(pid);
3830 retval = sched_setattr(p, &attr);
3837 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3838 * @pid: the pid in question.
3840 * Return: On success, the policy of the thread. Otherwise, a negative error
3843 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3845 struct task_struct *p;
3853 p = find_process_by_pid(pid);
3855 retval = security_task_getscheduler(p);
3858 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3865 * sys_sched_getparam - get the RT priority of a thread
3866 * @pid: the pid in question.
3867 * @param: structure containing the RT priority.
3869 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3872 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3874 struct sched_param lp = { .sched_priority = 0 };
3875 struct task_struct *p;
3878 if (!param || pid < 0)
3882 p = find_process_by_pid(pid);
3887 retval = security_task_getscheduler(p);
3891 if (task_has_rt_policy(p))
3892 lp.sched_priority = p->rt_priority;
3896 * This one might sleep, we cannot do it with a spinlock held ...
3898 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3907 static int sched_read_attr(struct sched_attr __user *uattr,
3908 struct sched_attr *attr,
3913 if (!access_ok(VERIFY_WRITE, uattr, usize))
3917 * If we're handed a smaller struct than we know of,
3918 * ensure all the unknown bits are 0 - i.e. old
3919 * user-space does not get uncomplete information.
3921 if (usize < sizeof(*attr)) {
3922 unsigned char *addr;
3925 addr = (void *)attr + usize;
3926 end = (void *)attr + sizeof(*attr);
3928 for (; addr < end; addr++) {
3936 ret = copy_to_user(uattr, attr, attr->size);
3944 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3945 * @pid: the pid in question.
3946 * @uattr: structure containing the extended parameters.
3947 * @size: sizeof(attr) for fwd/bwd comp.
3948 * @flags: for future extension.
3950 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
3951 unsigned int, size, unsigned int, flags)
3953 struct sched_attr attr = {
3954 .size = sizeof(struct sched_attr),
3956 struct task_struct *p;
3959 if (!uattr || pid < 0 || size > PAGE_SIZE ||
3960 size < SCHED_ATTR_SIZE_VER0 || flags)
3964 p = find_process_by_pid(pid);
3969 retval = security_task_getscheduler(p);
3973 attr.sched_policy = p->policy;
3974 if (p->sched_reset_on_fork)
3975 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
3976 if (task_has_dl_policy(p))
3977 __getparam_dl(p, &attr);
3978 else if (task_has_rt_policy(p))
3979 attr.sched_priority = p->rt_priority;
3981 attr.sched_nice = task_nice(p);
3985 retval = sched_read_attr(uattr, &attr, size);
3993 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
3995 cpumask_var_t cpus_allowed, new_mask;
3996 struct task_struct *p;
4001 p = find_process_by_pid(pid);
4007 /* Prevent p going away */
4011 if (p->flags & PF_NO_SETAFFINITY) {
4015 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4019 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4021 goto out_free_cpus_allowed;
4024 if (!check_same_owner(p)) {
4026 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4028 goto out_free_new_mask;
4033 retval = security_task_setscheduler(p);
4035 goto out_free_new_mask;
4038 cpuset_cpus_allowed(p, cpus_allowed);
4039 cpumask_and(new_mask, in_mask, cpus_allowed);
4042 * Since bandwidth control happens on root_domain basis,
4043 * if admission test is enabled, we only admit -deadline
4044 * tasks allowed to run on all the CPUs in the task's
4048 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4050 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4053 goto out_free_new_mask;
4059 retval = set_cpus_allowed_ptr(p, new_mask);
4062 cpuset_cpus_allowed(p, cpus_allowed);
4063 if (!cpumask_subset(new_mask, cpus_allowed)) {
4065 * We must have raced with a concurrent cpuset
4066 * update. Just reset the cpus_allowed to the
4067 * cpuset's cpus_allowed
4069 cpumask_copy(new_mask, cpus_allowed);
4074 free_cpumask_var(new_mask);
4075 out_free_cpus_allowed:
4076 free_cpumask_var(cpus_allowed);
4082 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4083 struct cpumask *new_mask)
4085 if (len < cpumask_size())
4086 cpumask_clear(new_mask);
4087 else if (len > cpumask_size())
4088 len = cpumask_size();
4090 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4094 * sys_sched_setaffinity - set the cpu affinity of a process
4095 * @pid: pid of the process
4096 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4097 * @user_mask_ptr: user-space pointer to the new cpu mask
4099 * Return: 0 on success. An error code otherwise.
4101 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4102 unsigned long __user *, user_mask_ptr)
4104 cpumask_var_t new_mask;
4107 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4110 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4112 retval = sched_setaffinity(pid, new_mask);
4113 free_cpumask_var(new_mask);
4117 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4119 struct task_struct *p;
4120 unsigned long flags;
4126 p = find_process_by_pid(pid);
4130 retval = security_task_getscheduler(p);
4134 raw_spin_lock_irqsave(&p->pi_lock, flags);
4135 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4136 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4145 * sys_sched_getaffinity - get the cpu affinity of a process
4146 * @pid: pid of the process
4147 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4148 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4150 * Return: 0 on success. An error code otherwise.
4152 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4153 unsigned long __user *, user_mask_ptr)
4158 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4160 if (len & (sizeof(unsigned long)-1))
4163 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4166 ret = sched_getaffinity(pid, mask);
4168 size_t retlen = min_t(size_t, len, cpumask_size());
4170 if (copy_to_user(user_mask_ptr, mask, retlen))
4175 free_cpumask_var(mask);
4181 * sys_sched_yield - yield the current processor to other threads.
4183 * This function yields the current CPU to other tasks. If there are no
4184 * other threads running on this CPU then this function will return.
4188 SYSCALL_DEFINE0(sched_yield)
4190 struct rq *rq = this_rq_lock();
4192 schedstat_inc(rq, yld_count);
4193 current->sched_class->yield_task(rq);
4196 * Since we are going to call schedule() anyway, there's
4197 * no need to preempt or enable interrupts:
4199 __release(rq->lock);
4200 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4201 do_raw_spin_unlock(&rq->lock);
4202 sched_preempt_enable_no_resched();
4209 static void __cond_resched(void)
4211 __preempt_count_add(PREEMPT_ACTIVE);
4213 __preempt_count_sub(PREEMPT_ACTIVE);
4216 int __sched _cond_resched(void)
4218 if (should_resched()) {
4224 EXPORT_SYMBOL(_cond_resched);
4227 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4228 * call schedule, and on return reacquire the lock.
4230 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4231 * operations here to prevent schedule() from being called twice (once via
4232 * spin_unlock(), once by hand).
4234 int __cond_resched_lock(spinlock_t *lock)
4236 int resched = should_resched();
4239 lockdep_assert_held(lock);
4241 if (spin_needbreak(lock) || resched) {
4252 EXPORT_SYMBOL(__cond_resched_lock);
4254 int __sched __cond_resched_softirq(void)
4256 BUG_ON(!in_softirq());
4258 if (should_resched()) {
4266 EXPORT_SYMBOL(__cond_resched_softirq);
4269 * yield - yield the current processor to other threads.
4271 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4273 * The scheduler is at all times free to pick the calling task as the most
4274 * eligible task to run, if removing the yield() call from your code breaks
4275 * it, its already broken.
4277 * Typical broken usage is:
4282 * where one assumes that yield() will let 'the other' process run that will
4283 * make event true. If the current task is a SCHED_FIFO task that will never
4284 * happen. Never use yield() as a progress guarantee!!
4286 * If you want to use yield() to wait for something, use wait_event().
4287 * If you want to use yield() to be 'nice' for others, use cond_resched().
4288 * If you still want to use yield(), do not!
4290 void __sched yield(void)
4292 set_current_state(TASK_RUNNING);
4295 EXPORT_SYMBOL(yield);
4298 * yield_to - yield the current processor to another thread in
4299 * your thread group, or accelerate that thread toward the
4300 * processor it's on.
4302 * @preempt: whether task preemption is allowed or not
4304 * It's the caller's job to ensure that the target task struct
4305 * can't go away on us before we can do any checks.
4308 * true (>0) if we indeed boosted the target task.
4309 * false (0) if we failed to boost the target.
4310 * -ESRCH if there's no task to yield to.
4312 int __sched yield_to(struct task_struct *p, bool preempt)
4314 struct task_struct *curr = current;
4315 struct rq *rq, *p_rq;
4316 unsigned long flags;
4319 local_irq_save(flags);
4325 * If we're the only runnable task on the rq and target rq also
4326 * has only one task, there's absolutely no point in yielding.
4328 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4333 double_rq_lock(rq, p_rq);
4334 if (task_rq(p) != p_rq) {
4335 double_rq_unlock(rq, p_rq);
4339 if (!curr->sched_class->yield_to_task)
4342 if (curr->sched_class != p->sched_class)
4345 if (task_running(p_rq, p) || p->state)
4348 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4350 schedstat_inc(rq, yld_count);
4352 * Make p's CPU reschedule; pick_next_entity takes care of
4355 if (preempt && rq != p_rq)
4360 double_rq_unlock(rq, p_rq);
4362 local_irq_restore(flags);
4369 EXPORT_SYMBOL_GPL(yield_to);
4372 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4373 * that process accounting knows that this is a task in IO wait state.
4375 void __sched io_schedule(void)
4377 struct rq *rq = raw_rq();
4379 delayacct_blkio_start();
4380 atomic_inc(&rq->nr_iowait);
4381 blk_flush_plug(current);
4382 current->in_iowait = 1;
4384 current->in_iowait = 0;
4385 atomic_dec(&rq->nr_iowait);
4386 delayacct_blkio_end();
4388 EXPORT_SYMBOL(io_schedule);
4390 long __sched io_schedule_timeout(long timeout)
4392 struct rq *rq = raw_rq();
4395 delayacct_blkio_start();
4396 atomic_inc(&rq->nr_iowait);
4397 blk_flush_plug(current);
4398 current->in_iowait = 1;
4399 ret = schedule_timeout(timeout);
4400 current->in_iowait = 0;
4401 atomic_dec(&rq->nr_iowait);
4402 delayacct_blkio_end();
4407 * sys_sched_get_priority_max - return maximum RT priority.
4408 * @policy: scheduling class.
4410 * Return: On success, this syscall returns the maximum
4411 * rt_priority that can be used by a given scheduling class.
4412 * On failure, a negative error code is returned.
4414 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4421 ret = MAX_USER_RT_PRIO-1;
4423 case SCHED_DEADLINE:
4434 * sys_sched_get_priority_min - return minimum RT priority.
4435 * @policy: scheduling class.
4437 * Return: On success, this syscall returns the minimum
4438 * rt_priority that can be used by a given scheduling class.
4439 * On failure, a negative error code is returned.
4441 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4450 case SCHED_DEADLINE:
4460 * sys_sched_rr_get_interval - return the default timeslice of a process.
4461 * @pid: pid of the process.
4462 * @interval: userspace pointer to the timeslice value.
4464 * this syscall writes the default timeslice value of a given process
4465 * into the user-space timespec buffer. A value of '0' means infinity.
4467 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4470 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4471 struct timespec __user *, interval)
4473 struct task_struct *p;
4474 unsigned int time_slice;
4475 unsigned long flags;
4485 p = find_process_by_pid(pid);
4489 retval = security_task_getscheduler(p);
4493 rq = task_rq_lock(p, &flags);
4495 if (p->sched_class->get_rr_interval)
4496 time_slice = p->sched_class->get_rr_interval(rq, p);
4497 task_rq_unlock(rq, p, &flags);
4500 jiffies_to_timespec(time_slice, &t);
4501 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4509 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4511 void sched_show_task(struct task_struct *p)
4513 unsigned long free = 0;
4517 state = p->state ? __ffs(p->state) + 1 : 0;
4518 printk(KERN_INFO "%-15.15s %c", p->comm,
4519 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4520 #if BITS_PER_LONG == 32
4521 if (state == TASK_RUNNING)
4522 printk(KERN_CONT " running ");
4524 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4526 if (state == TASK_RUNNING)
4527 printk(KERN_CONT " running task ");
4529 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4531 #ifdef CONFIG_DEBUG_STACK_USAGE
4532 free = stack_not_used(p);
4535 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4537 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4538 task_pid_nr(p), ppid,
4539 (unsigned long)task_thread_info(p)->flags);
4541 print_worker_info(KERN_INFO, p);
4542 show_stack(p, NULL);
4545 void show_state_filter(unsigned long state_filter)
4547 struct task_struct *g, *p;
4549 #if BITS_PER_LONG == 32
4551 " task PC stack pid father\n");
4554 " task PC stack pid father\n");
4557 for_each_process_thread(g, p) {
4559 * reset the NMI-timeout, listing all files on a slow
4560 * console might take a lot of time:
4562 touch_nmi_watchdog();
4563 if (!state_filter || (p->state & state_filter))
4567 touch_all_softlockup_watchdogs();
4569 #ifdef CONFIG_SCHED_DEBUG
4570 sysrq_sched_debug_show();
4574 * Only show locks if all tasks are dumped:
4577 debug_show_all_locks();
4580 void init_idle_bootup_task(struct task_struct *idle)
4582 idle->sched_class = &idle_sched_class;
4586 * init_idle - set up an idle thread for a given CPU
4587 * @idle: task in question
4588 * @cpu: cpu the idle task belongs to
4590 * NOTE: this function does not set the idle thread's NEED_RESCHED
4591 * flag, to make booting more robust.
4593 void init_idle(struct task_struct *idle, int cpu)
4595 struct rq *rq = cpu_rq(cpu);
4596 unsigned long flags;
4598 raw_spin_lock_irqsave(&rq->lock, flags);
4600 __sched_fork(0, idle);
4601 idle->state = TASK_RUNNING;
4602 idle->se.exec_start = sched_clock();
4604 do_set_cpus_allowed(idle, cpumask_of(cpu));
4606 * We're having a chicken and egg problem, even though we are
4607 * holding rq->lock, the cpu isn't yet set to this cpu so the
4608 * lockdep check in task_group() will fail.
4610 * Similar case to sched_fork(). / Alternatively we could
4611 * use task_rq_lock() here and obtain the other rq->lock.
4616 __set_task_cpu(idle, cpu);
4619 rq->curr = rq->idle = idle;
4620 idle->on_rq = TASK_ON_RQ_QUEUED;
4621 #if defined(CONFIG_SMP)
4624 raw_spin_unlock_irqrestore(&rq->lock, flags);
4626 /* Set the preempt count _outside_ the spinlocks! */
4627 init_idle_preempt_count(idle, cpu);
4630 * The idle tasks have their own, simple scheduling class:
4632 idle->sched_class = &idle_sched_class;
4633 ftrace_graph_init_idle_task(idle, cpu);
4634 vtime_init_idle(idle, cpu);
4635 #if defined(CONFIG_SMP)
4636 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4642 * move_queued_task - move a queued task to new rq.
4644 * Returns (locked) new rq. Old rq's lock is released.
4646 static struct rq *move_queued_task(struct task_struct *p, int new_cpu)
4648 struct rq *rq = task_rq(p);
4650 lockdep_assert_held(&rq->lock);
4652 dequeue_task(rq, p, 0);
4653 p->on_rq = TASK_ON_RQ_MIGRATING;
4654 set_task_cpu(p, new_cpu);
4655 raw_spin_unlock(&rq->lock);
4657 rq = cpu_rq(new_cpu);
4659 raw_spin_lock(&rq->lock);
4660 BUG_ON(task_cpu(p) != new_cpu);
4661 p->on_rq = TASK_ON_RQ_QUEUED;
4662 enqueue_task(rq, p, 0);
4663 check_preempt_curr(rq, p, 0);
4668 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4670 if (p->sched_class && p->sched_class->set_cpus_allowed)
4671 p->sched_class->set_cpus_allowed(p, new_mask);
4673 cpumask_copy(&p->cpus_allowed, new_mask);
4674 p->nr_cpus_allowed = cpumask_weight(new_mask);
4678 * This is how migration works:
4680 * 1) we invoke migration_cpu_stop() on the target CPU using
4682 * 2) stopper starts to run (implicitly forcing the migrated thread
4684 * 3) it checks whether the migrated task is still in the wrong runqueue.
4685 * 4) if it's in the wrong runqueue then the migration thread removes
4686 * it and puts it into the right queue.
4687 * 5) stopper completes and stop_one_cpu() returns and the migration
4692 * Change a given task's CPU affinity. Migrate the thread to a
4693 * proper CPU and schedule it away if the CPU it's executing on
4694 * is removed from the allowed bitmask.
4696 * NOTE: the caller must have a valid reference to the task, the
4697 * task must not exit() & deallocate itself prematurely. The
4698 * call is not atomic; no spinlocks may be held.
4700 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4702 unsigned long flags;
4704 unsigned int dest_cpu;
4707 rq = task_rq_lock(p, &flags);
4709 if (cpumask_equal(&p->cpus_allowed, new_mask))
4712 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4717 do_set_cpus_allowed(p, new_mask);
4719 /* Can the task run on the task's current CPU? If so, we're done */
4720 if (cpumask_test_cpu(task_cpu(p), new_mask))
4723 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4724 if (task_running(rq, p) || p->state == TASK_WAKING) {
4725 struct migration_arg arg = { p, dest_cpu };
4726 /* Need help from migration thread: drop lock and wait. */
4727 task_rq_unlock(rq, p, &flags);
4728 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4729 tlb_migrate_finish(p->mm);
4731 } else if (task_on_rq_queued(p))
4732 rq = move_queued_task(p, dest_cpu);
4734 task_rq_unlock(rq, p, &flags);
4738 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4741 * Move (not current) task off this cpu, onto dest cpu. We're doing
4742 * this because either it can't run here any more (set_cpus_allowed()
4743 * away from this CPU, or CPU going down), or because we're
4744 * attempting to rebalance this task on exec (sched_exec).
4746 * So we race with normal scheduler movements, but that's OK, as long
4747 * as the task is no longer on this CPU.
4749 * Returns non-zero if task was successfully migrated.
4751 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4756 if (unlikely(!cpu_active(dest_cpu)))
4759 rq = cpu_rq(src_cpu);
4761 raw_spin_lock(&p->pi_lock);
4762 raw_spin_lock(&rq->lock);
4763 /* Already moved. */
4764 if (task_cpu(p) != src_cpu)
4767 /* Affinity changed (again). */
4768 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4772 * If we're not on a rq, the next wake-up will ensure we're
4775 if (task_on_rq_queued(p))
4776 rq = move_queued_task(p, dest_cpu);
4780 raw_spin_unlock(&rq->lock);
4781 raw_spin_unlock(&p->pi_lock);
4785 #ifdef CONFIG_NUMA_BALANCING
4786 /* Migrate current task p to target_cpu */
4787 int migrate_task_to(struct task_struct *p, int target_cpu)
4789 struct migration_arg arg = { p, target_cpu };
4790 int curr_cpu = task_cpu(p);
4792 if (curr_cpu == target_cpu)
4795 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
4798 /* TODO: This is not properly updating schedstats */
4800 trace_sched_move_numa(p, curr_cpu, target_cpu);
4801 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
4805 * Requeue a task on a given node and accurately track the number of NUMA
4806 * tasks on the runqueues
4808 void sched_setnuma(struct task_struct *p, int nid)
4811 unsigned long flags;
4812 bool queued, running;
4814 rq = task_rq_lock(p, &flags);
4815 queued = task_on_rq_queued(p);
4816 running = task_current(rq, p);
4819 dequeue_task(rq, p, 0);
4821 put_prev_task(rq, p);
4823 p->numa_preferred_nid = nid;
4826 p->sched_class->set_curr_task(rq);
4828 enqueue_task(rq, p, 0);
4829 task_rq_unlock(rq, p, &flags);
4834 * migration_cpu_stop - this will be executed by a highprio stopper thread
4835 * and performs thread migration by bumping thread off CPU then
4836 * 'pushing' onto another runqueue.
4838 static int migration_cpu_stop(void *data)
4840 struct migration_arg *arg = data;
4843 * The original target cpu might have gone down and we might
4844 * be on another cpu but it doesn't matter.
4846 local_irq_disable();
4848 * We need to explicitly wake pending tasks before running
4849 * __migrate_task() such that we will not miss enforcing cpus_allowed
4850 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
4852 sched_ttwu_pending();
4853 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4858 #ifdef CONFIG_HOTPLUG_CPU
4861 * Ensures that the idle task is using init_mm right before its cpu goes
4864 void idle_task_exit(void)
4866 struct mm_struct *mm = current->active_mm;
4868 BUG_ON(cpu_online(smp_processor_id()));
4870 if (mm != &init_mm) {
4871 switch_mm(mm, &init_mm, current);
4872 finish_arch_post_lock_switch();
4878 * Since this CPU is going 'away' for a while, fold any nr_active delta
4879 * we might have. Assumes we're called after migrate_tasks() so that the
4880 * nr_active count is stable.
4882 * Also see the comment "Global load-average calculations".
4884 static void calc_load_migrate(struct rq *rq)
4886 long delta = calc_load_fold_active(rq);
4888 atomic_long_add(delta, &calc_load_tasks);
4891 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
4895 static const struct sched_class fake_sched_class = {
4896 .put_prev_task = put_prev_task_fake,
4899 static struct task_struct fake_task = {
4901 * Avoid pull_{rt,dl}_task()
4903 .prio = MAX_PRIO + 1,
4904 .sched_class = &fake_sched_class,
4908 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4909 * try_to_wake_up()->select_task_rq().
4911 * Called with rq->lock held even though we'er in stop_machine() and
4912 * there's no concurrency possible, we hold the required locks anyway
4913 * because of lock validation efforts.
4915 static void migrate_tasks(unsigned int dead_cpu)
4917 struct rq *rq = cpu_rq(dead_cpu);
4918 struct task_struct *next, *stop = rq->stop;
4922 * Fudge the rq selection such that the below task selection loop
4923 * doesn't get stuck on the currently eligible stop task.
4925 * We're currently inside stop_machine() and the rq is either stuck
4926 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4927 * either way we should never end up calling schedule() until we're
4933 * put_prev_task() and pick_next_task() sched
4934 * class method both need to have an up-to-date
4935 * value of rq->clock[_task]
4937 update_rq_clock(rq);
4941 * There's this thread running, bail when that's the only
4944 if (rq->nr_running == 1)
4947 next = pick_next_task(rq, &fake_task);
4949 next->sched_class->put_prev_task(rq, next);
4951 /* Find suitable destination for @next, with force if needed. */
4952 dest_cpu = select_fallback_rq(dead_cpu, next);
4953 raw_spin_unlock(&rq->lock);
4955 __migrate_task(next, dead_cpu, dest_cpu);
4957 raw_spin_lock(&rq->lock);
4963 #endif /* CONFIG_HOTPLUG_CPU */
4965 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4967 static struct ctl_table sd_ctl_dir[] = {
4969 .procname = "sched_domain",
4975 static struct ctl_table sd_ctl_root[] = {
4977 .procname = "kernel",
4979 .child = sd_ctl_dir,
4984 static struct ctl_table *sd_alloc_ctl_entry(int n)
4986 struct ctl_table *entry =
4987 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4992 static void sd_free_ctl_entry(struct ctl_table **tablep)
4994 struct ctl_table *entry;
4997 * In the intermediate directories, both the child directory and
4998 * procname are dynamically allocated and could fail but the mode
4999 * will always be set. In the lowest directory the names are
5000 * static strings and all have proc handlers.
5002 for (entry = *tablep; entry->mode; entry++) {
5004 sd_free_ctl_entry(&entry->child);
5005 if (entry->proc_handler == NULL)
5006 kfree(entry->procname);
5013 static int min_load_idx = 0;
5014 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
5017 set_table_entry(struct ctl_table *entry,
5018 const char *procname, void *data, int maxlen,
5019 umode_t mode, proc_handler *proc_handler,
5022 entry->procname = procname;
5024 entry->maxlen = maxlen;
5026 entry->proc_handler = proc_handler;
5029 entry->extra1 = &min_load_idx;
5030 entry->extra2 = &max_load_idx;
5034 static struct ctl_table *
5035 sd_alloc_ctl_domain_table(struct sched_domain *sd)
5037 struct ctl_table *table = sd_alloc_ctl_entry(14);
5042 set_table_entry(&table[0], "min_interval", &sd->min_interval,
5043 sizeof(long), 0644, proc_doulongvec_minmax, false);
5044 set_table_entry(&table[1], "max_interval", &sd->max_interval,
5045 sizeof(long), 0644, proc_doulongvec_minmax, false);
5046 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
5047 sizeof(int), 0644, proc_dointvec_minmax, true);
5048 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
5049 sizeof(int), 0644, proc_dointvec_minmax, true);
5050 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
5051 sizeof(int), 0644, proc_dointvec_minmax, true);
5052 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
5053 sizeof(int), 0644, proc_dointvec_minmax, true);
5054 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
5055 sizeof(int), 0644, proc_dointvec_minmax, true);
5056 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
5057 sizeof(int), 0644, proc_dointvec_minmax, false);
5058 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
5059 sizeof(int), 0644, proc_dointvec_minmax, false);
5060 set_table_entry(&table[9], "cache_nice_tries",
5061 &sd->cache_nice_tries,
5062 sizeof(int), 0644, proc_dointvec_minmax, false);
5063 set_table_entry(&table[10], "flags", &sd->flags,
5064 sizeof(int), 0644, proc_dointvec_minmax, false);
5065 set_table_entry(&table[11], "max_newidle_lb_cost",
5066 &sd->max_newidle_lb_cost,
5067 sizeof(long), 0644, proc_doulongvec_minmax, false);
5068 set_table_entry(&table[12], "name", sd->name,
5069 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
5070 /* &table[13] is terminator */
5075 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5077 struct ctl_table *entry, *table;
5078 struct sched_domain *sd;
5079 int domain_num = 0, i;
5082 for_each_domain(cpu, sd)
5084 entry = table = sd_alloc_ctl_entry(domain_num + 1);
5089 for_each_domain(cpu, sd) {
5090 snprintf(buf, 32, "domain%d", i);
5091 entry->procname = kstrdup(buf, GFP_KERNEL);
5093 entry->child = sd_alloc_ctl_domain_table(sd);
5100 static struct ctl_table_header *sd_sysctl_header;
5101 static void register_sched_domain_sysctl(void)
5103 int i, cpu_num = num_possible_cpus();
5104 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5107 WARN_ON(sd_ctl_dir[0].child);
5108 sd_ctl_dir[0].child = entry;
5113 for_each_possible_cpu(i) {
5114 snprintf(buf, 32, "cpu%d", i);
5115 entry->procname = kstrdup(buf, GFP_KERNEL);
5117 entry->child = sd_alloc_ctl_cpu_table(i);
5121 WARN_ON(sd_sysctl_header);
5122 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5125 /* may be called multiple times per register */
5126 static void unregister_sched_domain_sysctl(void)
5128 if (sd_sysctl_header)
5129 unregister_sysctl_table(sd_sysctl_header);
5130 sd_sysctl_header = NULL;
5131 if (sd_ctl_dir[0].child)
5132 sd_free_ctl_entry(&sd_ctl_dir[0].child);
5135 static void register_sched_domain_sysctl(void)
5138 static void unregister_sched_domain_sysctl(void)
5143 static void set_rq_online(struct rq *rq)
5146 const struct sched_class *class;
5148 cpumask_set_cpu(rq->cpu, rq->rd->online);
5151 for_each_class(class) {
5152 if (class->rq_online)
5153 class->rq_online(rq);
5158 static void set_rq_offline(struct rq *rq)
5161 const struct sched_class *class;
5163 for_each_class(class) {
5164 if (class->rq_offline)
5165 class->rq_offline(rq);
5168 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5174 * migration_call - callback that gets triggered when a CPU is added.
5175 * Here we can start up the necessary migration thread for the new CPU.
5178 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5180 int cpu = (long)hcpu;
5181 unsigned long flags;
5182 struct rq *rq = cpu_rq(cpu);
5184 switch (action & ~CPU_TASKS_FROZEN) {
5186 case CPU_UP_PREPARE:
5187 rq->calc_load_update = calc_load_update;
5191 /* Update our root-domain */
5192 raw_spin_lock_irqsave(&rq->lock, flags);
5194 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5198 raw_spin_unlock_irqrestore(&rq->lock, flags);
5201 #ifdef CONFIG_HOTPLUG_CPU
5203 sched_ttwu_pending();
5204 /* Update our root-domain */
5205 raw_spin_lock_irqsave(&rq->lock, flags);
5207 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5211 BUG_ON(rq->nr_running != 1); /* the migration thread */
5212 raw_spin_unlock_irqrestore(&rq->lock, flags);
5216 calc_load_migrate(rq);
5221 update_max_interval();
5227 * Register at high priority so that task migration (migrate_all_tasks)
5228 * happens before everything else. This has to be lower priority than
5229 * the notifier in the perf_event subsystem, though.
5231 static struct notifier_block migration_notifier = {
5232 .notifier_call = migration_call,
5233 .priority = CPU_PRI_MIGRATION,
5236 static void __cpuinit set_cpu_rq_start_time(void)
5238 int cpu = smp_processor_id();
5239 struct rq *rq = cpu_rq(cpu);
5240 rq->age_stamp = sched_clock_cpu(cpu);
5243 static int sched_cpu_active(struct notifier_block *nfb,
5244 unsigned long action, void *hcpu)
5246 switch (action & ~CPU_TASKS_FROZEN) {
5248 set_cpu_rq_start_time();
5250 case CPU_DOWN_FAILED:
5251 set_cpu_active((long)hcpu, true);
5258 static int sched_cpu_inactive(struct notifier_block *nfb,
5259 unsigned long action, void *hcpu)
5261 unsigned long flags;
5262 long cpu = (long)hcpu;
5265 switch (action & ~CPU_TASKS_FROZEN) {
5266 case CPU_DOWN_PREPARE:
5267 set_cpu_active(cpu, false);
5269 /* explicitly allow suspend */
5270 if (!(action & CPU_TASKS_FROZEN)) {
5274 rcu_read_lock_sched();
5275 dl_b = dl_bw_of(cpu);
5277 raw_spin_lock_irqsave(&dl_b->lock, flags);
5278 cpus = dl_bw_cpus(cpu);
5279 overflow = __dl_overflow(dl_b, cpus, 0, 0);
5280 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5282 rcu_read_unlock_sched();
5285 return notifier_from_errno(-EBUSY);
5293 static int __init migration_init(void)
5295 void *cpu = (void *)(long)smp_processor_id();
5298 /* Initialize migration for the boot CPU */
5299 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5300 BUG_ON(err == NOTIFY_BAD);
5301 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5302 register_cpu_notifier(&migration_notifier);
5304 /* Register cpu active notifiers */
5305 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5306 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5310 early_initcall(migration_init);
5315 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5317 #ifdef CONFIG_SCHED_DEBUG
5319 static __read_mostly int sched_debug_enabled;
5321 static int __init sched_debug_setup(char *str)
5323 sched_debug_enabled = 1;
5327 early_param("sched_debug", sched_debug_setup);
5329 static inline bool sched_debug(void)
5331 return sched_debug_enabled;
5334 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5335 struct cpumask *groupmask)
5337 struct sched_group *group = sd->groups;
5340 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5341 cpumask_clear(groupmask);
5343 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5345 if (!(sd->flags & SD_LOAD_BALANCE)) {
5346 printk("does not load-balance\n");
5348 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5353 printk(KERN_CONT "span %s level %s\n", str, sd->name);
5355 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5356 printk(KERN_ERR "ERROR: domain->span does not contain "
5359 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5360 printk(KERN_ERR "ERROR: domain->groups does not contain"
5364 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5368 printk(KERN_ERR "ERROR: group is NULL\n");
5373 * Even though we initialize ->capacity to something semi-sane,
5374 * we leave capacity_orig unset. This allows us to detect if
5375 * domain iteration is still funny without causing /0 traps.
5377 if (!group->sgc->capacity_orig) {
5378 printk(KERN_CONT "\n");
5379 printk(KERN_ERR "ERROR: domain->cpu_capacity not set\n");
5383 if (!cpumask_weight(sched_group_cpus(group))) {
5384 printk(KERN_CONT "\n");
5385 printk(KERN_ERR "ERROR: empty group\n");
5389 if (!(sd->flags & SD_OVERLAP) &&
5390 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5391 printk(KERN_CONT "\n");
5392 printk(KERN_ERR "ERROR: repeated CPUs\n");
5396 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5398 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5400 printk(KERN_CONT " %s", str);
5401 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5402 printk(KERN_CONT " (cpu_capacity = %d)",
5403 group->sgc->capacity);
5406 group = group->next;
5407 } while (group != sd->groups);
5408 printk(KERN_CONT "\n");
5410 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5411 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5414 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5415 printk(KERN_ERR "ERROR: parent span is not a superset "
5416 "of domain->span\n");
5420 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5424 if (!sched_debug_enabled)
5428 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5432 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5435 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5443 #else /* !CONFIG_SCHED_DEBUG */
5444 # define sched_domain_debug(sd, cpu) do { } while (0)
5445 static inline bool sched_debug(void)
5449 #endif /* CONFIG_SCHED_DEBUG */
5451 static int sd_degenerate(struct sched_domain *sd)
5453 if (cpumask_weight(sched_domain_span(sd)) == 1)
5456 /* Following flags need at least 2 groups */
5457 if (sd->flags & (SD_LOAD_BALANCE |
5458 SD_BALANCE_NEWIDLE |
5461 SD_SHARE_CPUCAPACITY |
5462 SD_SHARE_PKG_RESOURCES |
5463 SD_SHARE_POWERDOMAIN)) {
5464 if (sd->groups != sd->groups->next)
5468 /* Following flags don't use groups */
5469 if (sd->flags & (SD_WAKE_AFFINE))
5476 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5478 unsigned long cflags = sd->flags, pflags = parent->flags;
5480 if (sd_degenerate(parent))
5483 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5486 /* Flags needing groups don't count if only 1 group in parent */
5487 if (parent->groups == parent->groups->next) {
5488 pflags &= ~(SD_LOAD_BALANCE |
5489 SD_BALANCE_NEWIDLE |
5492 SD_SHARE_CPUCAPACITY |
5493 SD_SHARE_PKG_RESOURCES |
5495 SD_SHARE_POWERDOMAIN);
5496 if (nr_node_ids == 1)
5497 pflags &= ~SD_SERIALIZE;
5499 if (~cflags & pflags)
5505 static void free_rootdomain(struct rcu_head *rcu)
5507 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5509 cpupri_cleanup(&rd->cpupri);
5510 cpudl_cleanup(&rd->cpudl);
5511 free_cpumask_var(rd->dlo_mask);
5512 free_cpumask_var(rd->rto_mask);
5513 free_cpumask_var(rd->online);
5514 free_cpumask_var(rd->span);
5518 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5520 struct root_domain *old_rd = NULL;
5521 unsigned long flags;
5523 raw_spin_lock_irqsave(&rq->lock, flags);
5528 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5531 cpumask_clear_cpu(rq->cpu, old_rd->span);
5534 * If we dont want to free the old_rd yet then
5535 * set old_rd to NULL to skip the freeing later
5538 if (!atomic_dec_and_test(&old_rd->refcount))
5542 atomic_inc(&rd->refcount);
5545 cpumask_set_cpu(rq->cpu, rd->span);
5546 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5549 raw_spin_unlock_irqrestore(&rq->lock, flags);
5552 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5555 static int init_rootdomain(struct root_domain *rd)
5557 memset(rd, 0, sizeof(*rd));
5559 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5561 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5563 if (!alloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5565 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5568 init_dl_bw(&rd->dl_bw);
5569 if (cpudl_init(&rd->cpudl) != 0)
5572 if (cpupri_init(&rd->cpupri) != 0)
5577 free_cpumask_var(rd->rto_mask);
5579 free_cpumask_var(rd->dlo_mask);
5581 free_cpumask_var(rd->online);
5583 free_cpumask_var(rd->span);
5589 * By default the system creates a single root-domain with all cpus as
5590 * members (mimicking the global state we have today).
5592 struct root_domain def_root_domain;
5594 static void init_defrootdomain(void)
5596 init_rootdomain(&def_root_domain);
5598 atomic_set(&def_root_domain.refcount, 1);
5601 static struct root_domain *alloc_rootdomain(void)
5603 struct root_domain *rd;
5605 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5609 if (init_rootdomain(rd) != 0) {
5617 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5619 struct sched_group *tmp, *first;
5628 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5633 } while (sg != first);
5636 static void free_sched_domain(struct rcu_head *rcu)
5638 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5641 * If its an overlapping domain it has private groups, iterate and
5644 if (sd->flags & SD_OVERLAP) {
5645 free_sched_groups(sd->groups, 1);
5646 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5647 kfree(sd->groups->sgc);
5653 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5655 call_rcu(&sd->rcu, free_sched_domain);
5658 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5660 for (; sd; sd = sd->parent)
5661 destroy_sched_domain(sd, cpu);
5665 * Keep a special pointer to the highest sched_domain that has
5666 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5667 * allows us to avoid some pointer chasing select_idle_sibling().
5669 * Also keep a unique ID per domain (we use the first cpu number in
5670 * the cpumask of the domain), this allows us to quickly tell if
5671 * two cpus are in the same cache domain, see cpus_share_cache().
5673 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5674 DEFINE_PER_CPU(int, sd_llc_size);
5675 DEFINE_PER_CPU(int, sd_llc_id);
5676 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5677 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5678 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5680 static void update_top_cache_domain(int cpu)
5682 struct sched_domain *sd;
5683 struct sched_domain *busy_sd = NULL;
5687 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5689 id = cpumask_first(sched_domain_span(sd));
5690 size = cpumask_weight(sched_domain_span(sd));
5691 busy_sd = sd->parent; /* sd_busy */
5693 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5695 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5696 per_cpu(sd_llc_size, cpu) = size;
5697 per_cpu(sd_llc_id, cpu) = id;
5699 sd = lowest_flag_domain(cpu, SD_NUMA);
5700 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5702 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5703 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5707 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5708 * hold the hotplug lock.
5711 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5713 struct rq *rq = cpu_rq(cpu);
5714 struct sched_domain *tmp;
5716 /* Remove the sched domains which do not contribute to scheduling. */
5717 for (tmp = sd; tmp; ) {
5718 struct sched_domain *parent = tmp->parent;
5722 if (sd_parent_degenerate(tmp, parent)) {
5723 tmp->parent = parent->parent;
5725 parent->parent->child = tmp;
5727 * Transfer SD_PREFER_SIBLING down in case of a
5728 * degenerate parent; the spans match for this
5729 * so the property transfers.
5731 if (parent->flags & SD_PREFER_SIBLING)
5732 tmp->flags |= SD_PREFER_SIBLING;
5733 destroy_sched_domain(parent, cpu);
5738 if (sd && sd_degenerate(sd)) {
5741 destroy_sched_domain(tmp, cpu);
5746 sched_domain_debug(sd, cpu);
5748 rq_attach_root(rq, rd);
5750 rcu_assign_pointer(rq->sd, sd);
5751 destroy_sched_domains(tmp, cpu);
5753 update_top_cache_domain(cpu);
5756 /* cpus with isolated domains */
5757 static cpumask_var_t cpu_isolated_map;
5759 /* Setup the mask of cpus configured for isolated domains */
5760 static int __init isolated_cpu_setup(char *str)
5762 alloc_bootmem_cpumask_var(&cpu_isolated_map);
5763 cpulist_parse(str, cpu_isolated_map);
5767 __setup("isolcpus=", isolated_cpu_setup);
5770 struct sched_domain ** __percpu sd;
5771 struct root_domain *rd;
5782 * Build an iteration mask that can exclude certain CPUs from the upwards
5785 * Asymmetric node setups can result in situations where the domain tree is of
5786 * unequal depth, make sure to skip domains that already cover the entire
5789 * In that case build_sched_domains() will have terminated the iteration early
5790 * and our sibling sd spans will be empty. Domains should always include the
5791 * cpu they're built on, so check that.
5794 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5796 const struct cpumask *span = sched_domain_span(sd);
5797 struct sd_data *sdd = sd->private;
5798 struct sched_domain *sibling;
5801 for_each_cpu(i, span) {
5802 sibling = *per_cpu_ptr(sdd->sd, i);
5803 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5806 cpumask_set_cpu(i, sched_group_mask(sg));
5811 * Return the canonical balance cpu for this group, this is the first cpu
5812 * of this group that's also in the iteration mask.
5814 int group_balance_cpu(struct sched_group *sg)
5816 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5820 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5822 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5823 const struct cpumask *span = sched_domain_span(sd);
5824 struct cpumask *covered = sched_domains_tmpmask;
5825 struct sd_data *sdd = sd->private;
5826 struct sched_domain *sibling;
5829 cpumask_clear(covered);
5831 for_each_cpu(i, span) {
5832 struct cpumask *sg_span;
5834 if (cpumask_test_cpu(i, covered))
5837 sibling = *per_cpu_ptr(sdd->sd, i);
5839 /* See the comment near build_group_mask(). */
5840 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5843 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5844 GFP_KERNEL, cpu_to_node(cpu));
5849 sg_span = sched_group_cpus(sg);
5851 cpumask_copy(sg_span, sched_domain_span(sibling->child));
5853 cpumask_set_cpu(i, sg_span);
5855 cpumask_or(covered, covered, sg_span);
5857 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
5858 if (atomic_inc_return(&sg->sgc->ref) == 1)
5859 build_group_mask(sd, sg);
5862 * Initialize sgc->capacity such that even if we mess up the
5863 * domains and no possible iteration will get us here, we won't
5866 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
5867 sg->sgc->capacity_orig = sg->sgc->capacity;
5870 * Make sure the first group of this domain contains the
5871 * canonical balance cpu. Otherwise the sched_domain iteration
5872 * breaks. See update_sg_lb_stats().
5874 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5875 group_balance_cpu(sg) == cpu)
5885 sd->groups = groups;
5890 free_sched_groups(first, 0);
5895 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5897 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5898 struct sched_domain *child = sd->child;
5901 cpu = cpumask_first(sched_domain_span(child));
5904 *sg = *per_cpu_ptr(sdd->sg, cpu);
5905 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
5906 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
5913 * build_sched_groups will build a circular linked list of the groups
5914 * covered by the given span, and will set each group's ->cpumask correctly,
5915 * and ->cpu_capacity to 0.
5917 * Assumes the sched_domain tree is fully constructed
5920 build_sched_groups(struct sched_domain *sd, int cpu)
5922 struct sched_group *first = NULL, *last = NULL;
5923 struct sd_data *sdd = sd->private;
5924 const struct cpumask *span = sched_domain_span(sd);
5925 struct cpumask *covered;
5928 get_group(cpu, sdd, &sd->groups);
5929 atomic_inc(&sd->groups->ref);
5931 if (cpu != cpumask_first(span))
5934 lockdep_assert_held(&sched_domains_mutex);
5935 covered = sched_domains_tmpmask;
5937 cpumask_clear(covered);
5939 for_each_cpu(i, span) {
5940 struct sched_group *sg;
5943 if (cpumask_test_cpu(i, covered))
5946 group = get_group(i, sdd, &sg);
5947 cpumask_setall(sched_group_mask(sg));
5949 for_each_cpu(j, span) {
5950 if (get_group(j, sdd, NULL) != group)
5953 cpumask_set_cpu(j, covered);
5954 cpumask_set_cpu(j, sched_group_cpus(sg));
5969 * Initialize sched groups cpu_capacity.
5971 * cpu_capacity indicates the capacity of sched group, which is used while
5972 * distributing the load between different sched groups in a sched domain.
5973 * Typically cpu_capacity for all the groups in a sched domain will be same
5974 * unless there are asymmetries in the topology. If there are asymmetries,
5975 * group having more cpu_capacity will pickup more load compared to the
5976 * group having less cpu_capacity.
5978 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
5980 struct sched_group *sg = sd->groups;
5985 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5987 } while (sg != sd->groups);
5989 if (cpu != group_balance_cpu(sg))
5992 update_group_capacity(sd, cpu);
5993 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
5997 * Initializers for schedule domains
5998 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6001 static int default_relax_domain_level = -1;
6002 int sched_domain_level_max;
6004 static int __init setup_relax_domain_level(char *str)
6006 if (kstrtoint(str, 0, &default_relax_domain_level))
6007 pr_warn("Unable to set relax_domain_level\n");
6011 __setup("relax_domain_level=", setup_relax_domain_level);
6013 static void set_domain_attribute(struct sched_domain *sd,
6014 struct sched_domain_attr *attr)
6018 if (!attr || attr->relax_domain_level < 0) {
6019 if (default_relax_domain_level < 0)
6022 request = default_relax_domain_level;
6024 request = attr->relax_domain_level;
6025 if (request < sd->level) {
6026 /* turn off idle balance on this domain */
6027 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6029 /* turn on idle balance on this domain */
6030 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6034 static void __sdt_free(const struct cpumask *cpu_map);
6035 static int __sdt_alloc(const struct cpumask *cpu_map);
6037 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6038 const struct cpumask *cpu_map)
6042 if (!atomic_read(&d->rd->refcount))
6043 free_rootdomain(&d->rd->rcu); /* fall through */
6045 free_percpu(d->sd); /* fall through */
6047 __sdt_free(cpu_map); /* fall through */
6053 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6054 const struct cpumask *cpu_map)
6056 memset(d, 0, sizeof(*d));
6058 if (__sdt_alloc(cpu_map))
6059 return sa_sd_storage;
6060 d->sd = alloc_percpu(struct sched_domain *);
6062 return sa_sd_storage;
6063 d->rd = alloc_rootdomain();
6066 return sa_rootdomain;
6070 * NULL the sd_data elements we've used to build the sched_domain and
6071 * sched_group structure so that the subsequent __free_domain_allocs()
6072 * will not free the data we're using.
6074 static void claim_allocations(int cpu, struct sched_domain *sd)
6076 struct sd_data *sdd = sd->private;
6078 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6079 *per_cpu_ptr(sdd->sd, cpu) = NULL;
6081 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6082 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6084 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6085 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6089 static int sched_domains_numa_levels;
6090 static int *sched_domains_numa_distance;
6091 static struct cpumask ***sched_domains_numa_masks;
6092 static int sched_domains_curr_level;
6096 * SD_flags allowed in topology descriptions.
6098 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6099 * SD_SHARE_PKG_RESOURCES - describes shared caches
6100 * SD_NUMA - describes NUMA topologies
6101 * SD_SHARE_POWERDOMAIN - describes shared power domain
6104 * SD_ASYM_PACKING - describes SMT quirks
6106 #define TOPOLOGY_SD_FLAGS \
6107 (SD_SHARE_CPUCAPACITY | \
6108 SD_SHARE_PKG_RESOURCES | \
6111 SD_SHARE_POWERDOMAIN)
6113 static struct sched_domain *
6114 sd_init(struct sched_domain_topology_level *tl, int cpu)
6116 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6117 int sd_weight, sd_flags = 0;
6121 * Ugly hack to pass state to sd_numa_mask()...
6123 sched_domains_curr_level = tl->numa_level;
6126 sd_weight = cpumask_weight(tl->mask(cpu));
6129 sd_flags = (*tl->sd_flags)();
6130 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6131 "wrong sd_flags in topology description\n"))
6132 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6134 *sd = (struct sched_domain){
6135 .min_interval = sd_weight,
6136 .max_interval = 2*sd_weight,
6138 .imbalance_pct = 125,
6140 .cache_nice_tries = 0,
6147 .flags = 1*SD_LOAD_BALANCE
6148 | 1*SD_BALANCE_NEWIDLE
6153 | 0*SD_SHARE_CPUCAPACITY
6154 | 0*SD_SHARE_PKG_RESOURCES
6156 | 0*SD_PREFER_SIBLING
6161 .last_balance = jiffies,
6162 .balance_interval = sd_weight,
6164 .max_newidle_lb_cost = 0,
6165 .next_decay_max_lb_cost = jiffies,
6166 #ifdef CONFIG_SCHED_DEBUG
6172 * Convert topological properties into behaviour.
6175 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6176 sd->imbalance_pct = 110;
6177 sd->smt_gain = 1178; /* ~15% */
6179 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6180 sd->imbalance_pct = 117;
6181 sd->cache_nice_tries = 1;
6185 } else if (sd->flags & SD_NUMA) {
6186 sd->cache_nice_tries = 2;
6190 sd->flags |= SD_SERIALIZE;
6191 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6192 sd->flags &= ~(SD_BALANCE_EXEC |
6199 sd->flags |= SD_PREFER_SIBLING;
6200 sd->cache_nice_tries = 1;
6205 sd->private = &tl->data;
6211 * Topology list, bottom-up.
6213 static struct sched_domain_topology_level default_topology[] = {
6214 #ifdef CONFIG_SCHED_SMT
6215 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6217 #ifdef CONFIG_SCHED_MC
6218 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6220 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6224 struct sched_domain_topology_level *sched_domain_topology = default_topology;
6226 #define for_each_sd_topology(tl) \
6227 for (tl = sched_domain_topology; tl->mask; tl++)
6229 void set_sched_topology(struct sched_domain_topology_level *tl)
6231 sched_domain_topology = tl;
6236 static const struct cpumask *sd_numa_mask(int cpu)
6238 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6241 static void sched_numa_warn(const char *str)
6243 static int done = false;
6251 printk(KERN_WARNING "ERROR: %s\n\n", str);
6253 for (i = 0; i < nr_node_ids; i++) {
6254 printk(KERN_WARNING " ");
6255 for (j = 0; j < nr_node_ids; j++)
6256 printk(KERN_CONT "%02d ", node_distance(i,j));
6257 printk(KERN_CONT "\n");
6259 printk(KERN_WARNING "\n");
6262 static bool find_numa_distance(int distance)
6266 if (distance == node_distance(0, 0))
6269 for (i = 0; i < sched_domains_numa_levels; i++) {
6270 if (sched_domains_numa_distance[i] == distance)
6277 static void sched_init_numa(void)
6279 int next_distance, curr_distance = node_distance(0, 0);
6280 struct sched_domain_topology_level *tl;
6284 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6285 if (!sched_domains_numa_distance)
6289 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6290 * unique distances in the node_distance() table.
6292 * Assumes node_distance(0,j) includes all distances in
6293 * node_distance(i,j) in order to avoid cubic time.
6295 next_distance = curr_distance;
6296 for (i = 0; i < nr_node_ids; i++) {
6297 for (j = 0; j < nr_node_ids; j++) {
6298 for (k = 0; k < nr_node_ids; k++) {
6299 int distance = node_distance(i, k);
6301 if (distance > curr_distance &&
6302 (distance < next_distance ||
6303 next_distance == curr_distance))
6304 next_distance = distance;
6307 * While not a strong assumption it would be nice to know
6308 * about cases where if node A is connected to B, B is not
6309 * equally connected to A.
6311 if (sched_debug() && node_distance(k, i) != distance)
6312 sched_numa_warn("Node-distance not symmetric");
6314 if (sched_debug() && i && !find_numa_distance(distance))
6315 sched_numa_warn("Node-0 not representative");
6317 if (next_distance != curr_distance) {
6318 sched_domains_numa_distance[level++] = next_distance;
6319 sched_domains_numa_levels = level;
6320 curr_distance = next_distance;
6325 * In case of sched_debug() we verify the above assumption.
6331 * 'level' contains the number of unique distances, excluding the
6332 * identity distance node_distance(i,i).
6334 * The sched_domains_numa_distance[] array includes the actual distance
6339 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6340 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6341 * the array will contain less then 'level' members. This could be
6342 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6343 * in other functions.
6345 * We reset it to 'level' at the end of this function.
6347 sched_domains_numa_levels = 0;
6349 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6350 if (!sched_domains_numa_masks)
6354 * Now for each level, construct a mask per node which contains all
6355 * cpus of nodes that are that many hops away from us.
6357 for (i = 0; i < level; i++) {
6358 sched_domains_numa_masks[i] =
6359 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6360 if (!sched_domains_numa_masks[i])
6363 for (j = 0; j < nr_node_ids; j++) {
6364 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6368 sched_domains_numa_masks[i][j] = mask;
6370 for (k = 0; k < nr_node_ids; k++) {
6371 if (node_distance(j, k) > sched_domains_numa_distance[i])
6374 cpumask_or(mask, mask, cpumask_of_node(k));
6379 /* Compute default topology size */
6380 for (i = 0; sched_domain_topology[i].mask; i++);
6382 tl = kzalloc((i + level + 1) *
6383 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6388 * Copy the default topology bits..
6390 for (i = 0; sched_domain_topology[i].mask; i++)
6391 tl[i] = sched_domain_topology[i];
6394 * .. and append 'j' levels of NUMA goodness.
6396 for (j = 0; j < level; i++, j++) {
6397 tl[i] = (struct sched_domain_topology_level){
6398 .mask = sd_numa_mask,
6399 .sd_flags = cpu_numa_flags,
6400 .flags = SDTL_OVERLAP,
6406 sched_domain_topology = tl;
6408 sched_domains_numa_levels = level;
6411 static void sched_domains_numa_masks_set(int cpu)
6414 int node = cpu_to_node(cpu);
6416 for (i = 0; i < sched_domains_numa_levels; i++) {
6417 for (j = 0; j < nr_node_ids; j++) {
6418 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6419 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6424 static void sched_domains_numa_masks_clear(int cpu)
6427 for (i = 0; i < sched_domains_numa_levels; i++) {
6428 for (j = 0; j < nr_node_ids; j++)
6429 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6434 * Update sched_domains_numa_masks[level][node] array when new cpus
6437 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6438 unsigned long action,
6441 int cpu = (long)hcpu;
6443 switch (action & ~CPU_TASKS_FROZEN) {
6445 sched_domains_numa_masks_set(cpu);
6449 sched_domains_numa_masks_clear(cpu);
6459 static inline void sched_init_numa(void)
6463 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6464 unsigned long action,
6469 #endif /* CONFIG_NUMA */
6471 static int __sdt_alloc(const struct cpumask *cpu_map)
6473 struct sched_domain_topology_level *tl;
6476 for_each_sd_topology(tl) {
6477 struct sd_data *sdd = &tl->data;
6479 sdd->sd = alloc_percpu(struct sched_domain *);
6483 sdd->sg = alloc_percpu(struct sched_group *);
6487 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6491 for_each_cpu(j, cpu_map) {
6492 struct sched_domain *sd;
6493 struct sched_group *sg;
6494 struct sched_group_capacity *sgc;
6496 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6497 GFP_KERNEL, cpu_to_node(j));
6501 *per_cpu_ptr(sdd->sd, j) = sd;
6503 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6504 GFP_KERNEL, cpu_to_node(j));
6510 *per_cpu_ptr(sdd->sg, j) = sg;
6512 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6513 GFP_KERNEL, cpu_to_node(j));
6517 *per_cpu_ptr(sdd->sgc, j) = sgc;
6524 static void __sdt_free(const struct cpumask *cpu_map)
6526 struct sched_domain_topology_level *tl;
6529 for_each_sd_topology(tl) {
6530 struct sd_data *sdd = &tl->data;
6532 for_each_cpu(j, cpu_map) {
6533 struct sched_domain *sd;
6536 sd = *per_cpu_ptr(sdd->sd, j);
6537 if (sd && (sd->flags & SD_OVERLAP))
6538 free_sched_groups(sd->groups, 0);
6539 kfree(*per_cpu_ptr(sdd->sd, j));
6543 kfree(*per_cpu_ptr(sdd->sg, j));
6545 kfree(*per_cpu_ptr(sdd->sgc, j));
6547 free_percpu(sdd->sd);
6549 free_percpu(sdd->sg);
6551 free_percpu(sdd->sgc);
6556 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6557 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6558 struct sched_domain *child, int cpu)
6560 struct sched_domain *sd = sd_init(tl, cpu);
6564 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6566 sd->level = child->level + 1;
6567 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6571 if (!cpumask_subset(sched_domain_span(child),
6572 sched_domain_span(sd))) {
6573 pr_err("BUG: arch topology borken\n");
6574 #ifdef CONFIG_SCHED_DEBUG
6575 pr_err(" the %s domain not a subset of the %s domain\n",
6576 child->name, sd->name);
6578 /* Fixup, ensure @sd has at least @child cpus. */
6579 cpumask_or(sched_domain_span(sd),
6580 sched_domain_span(sd),
6581 sched_domain_span(child));
6585 set_domain_attribute(sd, attr);
6591 * Build sched domains for a given set of cpus and attach the sched domains
6592 * to the individual cpus
6594 static int build_sched_domains(const struct cpumask *cpu_map,
6595 struct sched_domain_attr *attr)
6597 enum s_alloc alloc_state;
6598 struct sched_domain *sd;
6600 int i, ret = -ENOMEM;
6602 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6603 if (alloc_state != sa_rootdomain)
6606 /* Set up domains for cpus specified by the cpu_map. */
6607 for_each_cpu(i, cpu_map) {
6608 struct sched_domain_topology_level *tl;
6611 for_each_sd_topology(tl) {
6612 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6613 if (tl == sched_domain_topology)
6614 *per_cpu_ptr(d.sd, i) = sd;
6615 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6616 sd->flags |= SD_OVERLAP;
6617 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6622 /* Build the groups for the domains */
6623 for_each_cpu(i, cpu_map) {
6624 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6625 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6626 if (sd->flags & SD_OVERLAP) {
6627 if (build_overlap_sched_groups(sd, i))
6630 if (build_sched_groups(sd, i))
6636 /* Calculate CPU capacity for physical packages and nodes */
6637 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6638 if (!cpumask_test_cpu(i, cpu_map))
6641 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6642 claim_allocations(i, sd);
6643 init_sched_groups_capacity(i, sd);
6647 /* Attach the domains */
6649 for_each_cpu(i, cpu_map) {
6650 sd = *per_cpu_ptr(d.sd, i);
6651 cpu_attach_domain(sd, d.rd, i);
6657 __free_domain_allocs(&d, alloc_state, cpu_map);
6661 static cpumask_var_t *doms_cur; /* current sched domains */
6662 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
6663 static struct sched_domain_attr *dattr_cur;
6664 /* attribues of custom domains in 'doms_cur' */
6667 * Special case: If a kmalloc of a doms_cur partition (array of
6668 * cpumask) fails, then fallback to a single sched domain,
6669 * as determined by the single cpumask fallback_doms.
6671 static cpumask_var_t fallback_doms;
6674 * arch_update_cpu_topology lets virtualized architectures update the
6675 * cpu core maps. It is supposed to return 1 if the topology changed
6676 * or 0 if it stayed the same.
6678 int __weak arch_update_cpu_topology(void)
6683 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
6686 cpumask_var_t *doms;
6688 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
6691 for (i = 0; i < ndoms; i++) {
6692 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
6693 free_sched_domains(doms, i);
6700 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
6703 for (i = 0; i < ndoms; i++)
6704 free_cpumask_var(doms[i]);
6709 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6710 * For now this just excludes isolated cpus, but could be used to
6711 * exclude other special cases in the future.
6713 static int init_sched_domains(const struct cpumask *cpu_map)
6717 arch_update_cpu_topology();
6719 doms_cur = alloc_sched_domains(ndoms_cur);
6721 doms_cur = &fallback_doms;
6722 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
6723 err = build_sched_domains(doms_cur[0], NULL);
6724 register_sched_domain_sysctl();
6730 * Detach sched domains from a group of cpus specified in cpu_map
6731 * These cpus will now be attached to the NULL domain
6733 static void detach_destroy_domains(const struct cpumask *cpu_map)
6738 for_each_cpu(i, cpu_map)
6739 cpu_attach_domain(NULL, &def_root_domain, i);
6743 /* handle null as "default" */
6744 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
6745 struct sched_domain_attr *new, int idx_new)
6747 struct sched_domain_attr tmp;
6754 return !memcmp(cur ? (cur + idx_cur) : &tmp,
6755 new ? (new + idx_new) : &tmp,
6756 sizeof(struct sched_domain_attr));
6760 * Partition sched domains as specified by the 'ndoms_new'
6761 * cpumasks in the array doms_new[] of cpumasks. This compares
6762 * doms_new[] to the current sched domain partitioning, doms_cur[].
6763 * It destroys each deleted domain and builds each new domain.
6765 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6766 * The masks don't intersect (don't overlap.) We should setup one
6767 * sched domain for each mask. CPUs not in any of the cpumasks will
6768 * not be load balanced. If the same cpumask appears both in the
6769 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6772 * The passed in 'doms_new' should be allocated using
6773 * alloc_sched_domains. This routine takes ownership of it and will
6774 * free_sched_domains it when done with it. If the caller failed the
6775 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6776 * and partition_sched_domains() will fallback to the single partition
6777 * 'fallback_doms', it also forces the domains to be rebuilt.
6779 * If doms_new == NULL it will be replaced with cpu_online_mask.
6780 * ndoms_new == 0 is a special case for destroying existing domains,
6781 * and it will not create the default domain.
6783 * Call with hotplug lock held
6785 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
6786 struct sched_domain_attr *dattr_new)
6791 mutex_lock(&sched_domains_mutex);
6793 /* always unregister in case we don't destroy any domains */
6794 unregister_sched_domain_sysctl();
6796 /* Let architecture update cpu core mappings. */
6797 new_topology = arch_update_cpu_topology();
6799 n = doms_new ? ndoms_new : 0;
6801 /* Destroy deleted domains */
6802 for (i = 0; i < ndoms_cur; i++) {
6803 for (j = 0; j < n && !new_topology; j++) {
6804 if (cpumask_equal(doms_cur[i], doms_new[j])
6805 && dattrs_equal(dattr_cur, i, dattr_new, j))
6808 /* no match - a current sched domain not in new doms_new[] */
6809 detach_destroy_domains(doms_cur[i]);
6815 if (doms_new == NULL) {
6817 doms_new = &fallback_doms;
6818 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
6819 WARN_ON_ONCE(dattr_new);
6822 /* Build new domains */
6823 for (i = 0; i < ndoms_new; i++) {
6824 for (j = 0; j < n && !new_topology; j++) {
6825 if (cpumask_equal(doms_new[i], doms_cur[j])
6826 && dattrs_equal(dattr_new, i, dattr_cur, j))
6829 /* no match - add a new doms_new */
6830 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
6835 /* Remember the new sched domains */
6836 if (doms_cur != &fallback_doms)
6837 free_sched_domains(doms_cur, ndoms_cur);
6838 kfree(dattr_cur); /* kfree(NULL) is safe */
6839 doms_cur = doms_new;
6840 dattr_cur = dattr_new;
6841 ndoms_cur = ndoms_new;
6843 register_sched_domain_sysctl();
6845 mutex_unlock(&sched_domains_mutex);
6848 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
6851 * Update cpusets according to cpu_active mask. If cpusets are
6852 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6853 * around partition_sched_domains().
6855 * If we come here as part of a suspend/resume, don't touch cpusets because we
6856 * want to restore it back to its original state upon resume anyway.
6858 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
6862 case CPU_ONLINE_FROZEN:
6863 case CPU_DOWN_FAILED_FROZEN:
6866 * num_cpus_frozen tracks how many CPUs are involved in suspend
6867 * resume sequence. As long as this is not the last online
6868 * operation in the resume sequence, just build a single sched
6869 * domain, ignoring cpusets.
6872 if (likely(num_cpus_frozen)) {
6873 partition_sched_domains(1, NULL, NULL);
6878 * This is the last CPU online operation. So fall through and
6879 * restore the original sched domains by considering the
6880 * cpuset configurations.
6884 case CPU_DOWN_FAILED:
6885 cpuset_update_active_cpus(true);
6893 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
6897 case CPU_DOWN_PREPARE:
6898 cpuset_update_active_cpus(false);
6900 case CPU_DOWN_PREPARE_FROZEN:
6902 partition_sched_domains(1, NULL, NULL);
6910 void __init sched_init_smp(void)
6912 cpumask_var_t non_isolated_cpus;
6914 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
6915 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
6920 * There's no userspace yet to cause hotplug operations; hence all the
6921 * cpu masks are stable and all blatant races in the below code cannot
6924 mutex_lock(&sched_domains_mutex);
6925 init_sched_domains(cpu_active_mask);
6926 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
6927 if (cpumask_empty(non_isolated_cpus))
6928 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
6929 mutex_unlock(&sched_domains_mutex);
6931 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
6932 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
6933 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
6937 /* Move init over to a non-isolated CPU */
6938 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
6940 sched_init_granularity();
6941 free_cpumask_var(non_isolated_cpus);
6943 init_sched_rt_class();
6944 init_sched_dl_class();
6947 void __init sched_init_smp(void)
6949 sched_init_granularity();
6951 #endif /* CONFIG_SMP */
6953 const_debug unsigned int sysctl_timer_migration = 1;
6955 int in_sched_functions(unsigned long addr)
6957 return in_lock_functions(addr) ||
6958 (addr >= (unsigned long)__sched_text_start
6959 && addr < (unsigned long)__sched_text_end);
6962 #ifdef CONFIG_CGROUP_SCHED
6964 * Default task group.
6965 * Every task in system belongs to this group at bootup.
6967 struct task_group root_task_group;
6968 LIST_HEAD(task_groups);
6971 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
6973 void __init sched_init(void)
6976 unsigned long alloc_size = 0, ptr;
6978 #ifdef CONFIG_FAIR_GROUP_SCHED
6979 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6981 #ifdef CONFIG_RT_GROUP_SCHED
6982 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
6984 #ifdef CONFIG_CPUMASK_OFFSTACK
6985 alloc_size += num_possible_cpus() * cpumask_size();
6988 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
6990 #ifdef CONFIG_FAIR_GROUP_SCHED
6991 root_task_group.se = (struct sched_entity **)ptr;
6992 ptr += nr_cpu_ids * sizeof(void **);
6994 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
6995 ptr += nr_cpu_ids * sizeof(void **);
6997 #endif /* CONFIG_FAIR_GROUP_SCHED */
6998 #ifdef CONFIG_RT_GROUP_SCHED
6999 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7000 ptr += nr_cpu_ids * sizeof(void **);
7002 root_task_group.rt_rq = (struct rt_rq **)ptr;
7003 ptr += nr_cpu_ids * sizeof(void **);
7005 #endif /* CONFIG_RT_GROUP_SCHED */
7006 #ifdef CONFIG_CPUMASK_OFFSTACK
7007 for_each_possible_cpu(i) {
7008 per_cpu(load_balance_mask, i) = (void *)ptr;
7009 ptr += cpumask_size();
7011 #endif /* CONFIG_CPUMASK_OFFSTACK */
7014 init_rt_bandwidth(&def_rt_bandwidth,
7015 global_rt_period(), global_rt_runtime());
7016 init_dl_bandwidth(&def_dl_bandwidth,
7017 global_rt_period(), global_rt_runtime());
7020 init_defrootdomain();
7023 #ifdef CONFIG_RT_GROUP_SCHED
7024 init_rt_bandwidth(&root_task_group.rt_bandwidth,
7025 global_rt_period(), global_rt_runtime());
7026 #endif /* CONFIG_RT_GROUP_SCHED */
7028 #ifdef CONFIG_CGROUP_SCHED
7029 list_add(&root_task_group.list, &task_groups);
7030 INIT_LIST_HEAD(&root_task_group.children);
7031 INIT_LIST_HEAD(&root_task_group.siblings);
7032 autogroup_init(&init_task);
7034 #endif /* CONFIG_CGROUP_SCHED */
7036 for_each_possible_cpu(i) {
7040 raw_spin_lock_init(&rq->lock);
7042 rq->calc_load_active = 0;
7043 rq->calc_load_update = jiffies + LOAD_FREQ;
7044 init_cfs_rq(&rq->cfs);
7045 init_rt_rq(&rq->rt, rq);
7046 init_dl_rq(&rq->dl, rq);
7047 #ifdef CONFIG_FAIR_GROUP_SCHED
7048 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7049 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7051 * How much cpu bandwidth does root_task_group get?
7053 * In case of task-groups formed thr' the cgroup filesystem, it
7054 * gets 100% of the cpu resources in the system. This overall
7055 * system cpu resource is divided among the tasks of
7056 * root_task_group and its child task-groups in a fair manner,
7057 * based on each entity's (task or task-group's) weight
7058 * (se->load.weight).
7060 * In other words, if root_task_group has 10 tasks of weight
7061 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7062 * then A0's share of the cpu resource is:
7064 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7066 * We achieve this by letting root_task_group's tasks sit
7067 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7069 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7070 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7071 #endif /* CONFIG_FAIR_GROUP_SCHED */
7073 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7074 #ifdef CONFIG_RT_GROUP_SCHED
7075 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7078 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7079 rq->cpu_load[j] = 0;
7081 rq->last_load_update_tick = jiffies;
7086 rq->cpu_capacity = SCHED_CAPACITY_SCALE;
7087 rq->post_schedule = 0;
7088 rq->active_balance = 0;
7089 rq->next_balance = jiffies;
7094 rq->avg_idle = 2*sysctl_sched_migration_cost;
7095 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7097 INIT_LIST_HEAD(&rq->cfs_tasks);
7099 rq_attach_root(rq, &def_root_domain);
7100 #ifdef CONFIG_NO_HZ_COMMON
7103 #ifdef CONFIG_NO_HZ_FULL
7104 rq->last_sched_tick = 0;
7108 atomic_set(&rq->nr_iowait, 0);
7111 set_load_weight(&init_task);
7113 #ifdef CONFIG_PREEMPT_NOTIFIERS
7114 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7118 * The boot idle thread does lazy MMU switching as well:
7120 atomic_inc(&init_mm.mm_count);
7121 enter_lazy_tlb(&init_mm, current);
7124 * Make us the idle thread. Technically, schedule() should not be
7125 * called from this thread, however somewhere below it might be,
7126 * but because we are the idle thread, we just pick up running again
7127 * when this runqueue becomes "idle".
7129 init_idle(current, smp_processor_id());
7131 calc_load_update = jiffies + LOAD_FREQ;
7134 * During early bootup we pretend to be a normal task:
7136 current->sched_class = &fair_sched_class;
7139 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7140 /* May be allocated at isolcpus cmdline parse time */
7141 if (cpu_isolated_map == NULL)
7142 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7143 idle_thread_set_boot_cpu();
7144 set_cpu_rq_start_time();
7146 init_sched_fair_class();
7148 scheduler_running = 1;
7151 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7152 static inline int preempt_count_equals(int preempt_offset)
7154 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
7156 return (nested == preempt_offset);
7159 void __might_sleep(const char *file, int line, int preempt_offset)
7161 static unsigned long prev_jiffy; /* ratelimiting */
7163 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7164 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7165 !is_idle_task(current)) ||
7166 system_state != SYSTEM_RUNNING || oops_in_progress)
7168 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7170 prev_jiffy = jiffies;
7173 "BUG: sleeping function called from invalid context at %s:%d\n",
7176 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7177 in_atomic(), irqs_disabled(),
7178 current->pid, current->comm);
7180 debug_show_held_locks(current);
7181 if (irqs_disabled())
7182 print_irqtrace_events(current);
7183 #ifdef CONFIG_DEBUG_PREEMPT
7184 if (!preempt_count_equals(preempt_offset)) {
7185 pr_err("Preemption disabled at:");
7186 print_ip_sym(current->preempt_disable_ip);
7192 EXPORT_SYMBOL(__might_sleep);
7195 #ifdef CONFIG_MAGIC_SYSRQ
7196 static void normalize_task(struct rq *rq, struct task_struct *p)
7198 const struct sched_class *prev_class = p->sched_class;
7199 struct sched_attr attr = {
7200 .sched_policy = SCHED_NORMAL,
7202 int old_prio = p->prio;
7205 queued = task_on_rq_queued(p);
7207 dequeue_task(rq, p, 0);
7208 __setscheduler(rq, p, &attr);
7210 enqueue_task(rq, p, 0);
7214 check_class_changed(rq, p, prev_class, old_prio);
7217 void normalize_rt_tasks(void)
7219 struct task_struct *g, *p;
7220 unsigned long flags;
7223 read_lock(&tasklist_lock);
7224 for_each_process_thread(g, p) {
7226 * Only normalize user tasks:
7228 if (p->flags & PF_KTHREAD)
7231 p->se.exec_start = 0;
7232 #ifdef CONFIG_SCHEDSTATS
7233 p->se.statistics.wait_start = 0;
7234 p->se.statistics.sleep_start = 0;
7235 p->se.statistics.block_start = 0;
7238 if (!dl_task(p) && !rt_task(p)) {
7240 * Renice negative nice level userspace
7243 if (task_nice(p) < 0)
7244 set_user_nice(p, 0);
7248 rq = task_rq_lock(p, &flags);
7249 normalize_task(rq, p);
7250 task_rq_unlock(rq, p, &flags);
7252 read_unlock(&tasklist_lock);
7255 #endif /* CONFIG_MAGIC_SYSRQ */
7257 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7259 * These functions are only useful for the IA64 MCA handling, or kdb.
7261 * They can only be called when the whole system has been
7262 * stopped - every CPU needs to be quiescent, and no scheduling
7263 * activity can take place. Using them for anything else would
7264 * be a serious bug, and as a result, they aren't even visible
7265 * under any other configuration.
7269 * curr_task - return the current task for a given cpu.
7270 * @cpu: the processor in question.
7272 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7274 * Return: The current task for @cpu.
7276 struct task_struct *curr_task(int cpu)
7278 return cpu_curr(cpu);
7281 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7285 * set_curr_task - set the current task for a given cpu.
7286 * @cpu: the processor in question.
7287 * @p: the task pointer to set.
7289 * Description: This function must only be used when non-maskable interrupts
7290 * are serviced on a separate stack. It allows the architecture to switch the
7291 * notion of the current task on a cpu in a non-blocking manner. This function
7292 * must be called with all CPU's synchronized, and interrupts disabled, the
7293 * and caller must save the original value of the current task (see
7294 * curr_task() above) and restore that value before reenabling interrupts and
7295 * re-starting the system.
7297 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7299 void set_curr_task(int cpu, struct task_struct *p)
7306 #ifdef CONFIG_CGROUP_SCHED
7307 /* task_group_lock serializes the addition/removal of task groups */
7308 static DEFINE_SPINLOCK(task_group_lock);
7310 static void free_sched_group(struct task_group *tg)
7312 free_fair_sched_group(tg);
7313 free_rt_sched_group(tg);
7318 /* allocate runqueue etc for a new task group */
7319 struct task_group *sched_create_group(struct task_group *parent)
7321 struct task_group *tg;
7323 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7325 return ERR_PTR(-ENOMEM);
7327 if (!alloc_fair_sched_group(tg, parent))
7330 if (!alloc_rt_sched_group(tg, parent))
7336 free_sched_group(tg);
7337 return ERR_PTR(-ENOMEM);
7340 void sched_online_group(struct task_group *tg, struct task_group *parent)
7342 unsigned long flags;
7344 spin_lock_irqsave(&task_group_lock, flags);
7345 list_add_rcu(&tg->list, &task_groups);
7347 WARN_ON(!parent); /* root should already exist */
7349 tg->parent = parent;
7350 INIT_LIST_HEAD(&tg->children);
7351 list_add_rcu(&tg->siblings, &parent->children);
7352 spin_unlock_irqrestore(&task_group_lock, flags);
7355 /* rcu callback to free various structures associated with a task group */
7356 static void free_sched_group_rcu(struct rcu_head *rhp)
7358 /* now it should be safe to free those cfs_rqs */
7359 free_sched_group(container_of(rhp, struct task_group, rcu));
7362 /* Destroy runqueue etc associated with a task group */
7363 void sched_destroy_group(struct task_group *tg)
7365 /* wait for possible concurrent references to cfs_rqs complete */
7366 call_rcu(&tg->rcu, free_sched_group_rcu);
7369 void sched_offline_group(struct task_group *tg)
7371 unsigned long flags;
7374 /* end participation in shares distribution */
7375 for_each_possible_cpu(i)
7376 unregister_fair_sched_group(tg, i);
7378 spin_lock_irqsave(&task_group_lock, flags);
7379 list_del_rcu(&tg->list);
7380 list_del_rcu(&tg->siblings);
7381 spin_unlock_irqrestore(&task_group_lock, flags);
7384 /* change task's runqueue when it moves between groups.
7385 * The caller of this function should have put the task in its new group
7386 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7387 * reflect its new group.
7389 void sched_move_task(struct task_struct *tsk)
7391 struct task_group *tg;
7392 int queued, running;
7393 unsigned long flags;
7396 rq = task_rq_lock(tsk, &flags);
7398 running = task_current(rq, tsk);
7399 queued = task_on_rq_queued(tsk);
7402 dequeue_task(rq, tsk, 0);
7403 if (unlikely(running))
7404 put_prev_task(rq, tsk);
7406 tg = container_of(task_css_check(tsk, cpu_cgrp_id,
7407 lockdep_is_held(&tsk->sighand->siglock)),
7408 struct task_group, css);
7409 tg = autogroup_task_group(tsk, tg);
7410 tsk->sched_task_group = tg;
7412 #ifdef CONFIG_FAIR_GROUP_SCHED
7413 if (tsk->sched_class->task_move_group)
7414 tsk->sched_class->task_move_group(tsk, queued);
7417 set_task_rq(tsk, task_cpu(tsk));
7419 if (unlikely(running))
7420 tsk->sched_class->set_curr_task(rq);
7422 enqueue_task(rq, tsk, 0);
7424 task_rq_unlock(rq, tsk, &flags);
7426 #endif /* CONFIG_CGROUP_SCHED */
7428 #ifdef CONFIG_RT_GROUP_SCHED
7430 * Ensure that the real time constraints are schedulable.
7432 static DEFINE_MUTEX(rt_constraints_mutex);
7434 /* Must be called with tasklist_lock held */
7435 static inline int tg_has_rt_tasks(struct task_group *tg)
7437 struct task_struct *g, *p;
7439 for_each_process_thread(g, p) {
7440 if (rt_task(p) && task_group(p) == tg)
7447 struct rt_schedulable_data {
7448 struct task_group *tg;
7453 static int tg_rt_schedulable(struct task_group *tg, void *data)
7455 struct rt_schedulable_data *d = data;
7456 struct task_group *child;
7457 unsigned long total, sum = 0;
7458 u64 period, runtime;
7460 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7461 runtime = tg->rt_bandwidth.rt_runtime;
7464 period = d->rt_period;
7465 runtime = d->rt_runtime;
7469 * Cannot have more runtime than the period.
7471 if (runtime > period && runtime != RUNTIME_INF)
7475 * Ensure we don't starve existing RT tasks.
7477 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7480 total = to_ratio(period, runtime);
7483 * Nobody can have more than the global setting allows.
7485 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7489 * The sum of our children's runtime should not exceed our own.
7491 list_for_each_entry_rcu(child, &tg->children, siblings) {
7492 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7493 runtime = child->rt_bandwidth.rt_runtime;
7495 if (child == d->tg) {
7496 period = d->rt_period;
7497 runtime = d->rt_runtime;
7500 sum += to_ratio(period, runtime);
7509 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7513 struct rt_schedulable_data data = {
7515 .rt_period = period,
7516 .rt_runtime = runtime,
7520 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7526 static int tg_set_rt_bandwidth(struct task_group *tg,
7527 u64 rt_period, u64 rt_runtime)
7531 mutex_lock(&rt_constraints_mutex);
7532 read_lock(&tasklist_lock);
7533 err = __rt_schedulable(tg, rt_period, rt_runtime);
7537 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7538 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7539 tg->rt_bandwidth.rt_runtime = rt_runtime;
7541 for_each_possible_cpu(i) {
7542 struct rt_rq *rt_rq = tg->rt_rq[i];
7544 raw_spin_lock(&rt_rq->rt_runtime_lock);
7545 rt_rq->rt_runtime = rt_runtime;
7546 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7548 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7550 read_unlock(&tasklist_lock);
7551 mutex_unlock(&rt_constraints_mutex);
7556 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7558 u64 rt_runtime, rt_period;
7560 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7561 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7562 if (rt_runtime_us < 0)
7563 rt_runtime = RUNTIME_INF;
7565 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7568 static long sched_group_rt_runtime(struct task_group *tg)
7572 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7575 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7576 do_div(rt_runtime_us, NSEC_PER_USEC);
7577 return rt_runtime_us;
7580 static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us)
7582 u64 rt_runtime, rt_period;
7584 rt_period = (u64)rt_period_us * NSEC_PER_USEC;
7585 rt_runtime = tg->rt_bandwidth.rt_runtime;
7590 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7593 static long sched_group_rt_period(struct task_group *tg)
7597 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7598 do_div(rt_period_us, NSEC_PER_USEC);
7599 return rt_period_us;
7601 #endif /* CONFIG_RT_GROUP_SCHED */
7603 #ifdef CONFIG_RT_GROUP_SCHED
7604 static int sched_rt_global_constraints(void)
7608 mutex_lock(&rt_constraints_mutex);
7609 read_lock(&tasklist_lock);
7610 ret = __rt_schedulable(NULL, 0, 0);
7611 read_unlock(&tasklist_lock);
7612 mutex_unlock(&rt_constraints_mutex);
7617 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7619 /* Don't accept realtime tasks when there is no way for them to run */
7620 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
7626 #else /* !CONFIG_RT_GROUP_SCHED */
7627 static int sched_rt_global_constraints(void)
7629 unsigned long flags;
7632 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
7633 for_each_possible_cpu(i) {
7634 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
7636 raw_spin_lock(&rt_rq->rt_runtime_lock);
7637 rt_rq->rt_runtime = global_rt_runtime();
7638 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7640 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
7644 #endif /* CONFIG_RT_GROUP_SCHED */
7646 static int sched_dl_global_constraints(void)
7648 u64 runtime = global_rt_runtime();
7649 u64 period = global_rt_period();
7650 u64 new_bw = to_ratio(period, runtime);
7653 unsigned long flags;
7656 * Here we want to check the bandwidth not being set to some
7657 * value smaller than the currently allocated bandwidth in
7658 * any of the root_domains.
7660 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7661 * cycling on root_domains... Discussion on different/better
7662 * solutions is welcome!
7664 for_each_possible_cpu(cpu) {
7665 rcu_read_lock_sched();
7666 dl_b = dl_bw_of(cpu);
7668 raw_spin_lock_irqsave(&dl_b->lock, flags);
7669 if (new_bw < dl_b->total_bw)
7671 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7673 rcu_read_unlock_sched();
7682 static void sched_dl_do_global(void)
7687 unsigned long flags;
7689 def_dl_bandwidth.dl_period = global_rt_period();
7690 def_dl_bandwidth.dl_runtime = global_rt_runtime();
7692 if (global_rt_runtime() != RUNTIME_INF)
7693 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
7696 * FIXME: As above...
7698 for_each_possible_cpu(cpu) {
7699 rcu_read_lock_sched();
7700 dl_b = dl_bw_of(cpu);
7702 raw_spin_lock_irqsave(&dl_b->lock, flags);
7704 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7706 rcu_read_unlock_sched();
7710 static int sched_rt_global_validate(void)
7712 if (sysctl_sched_rt_period <= 0)
7715 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
7716 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
7722 static void sched_rt_do_global(void)
7724 def_rt_bandwidth.rt_runtime = global_rt_runtime();
7725 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
7728 int sched_rt_handler(struct ctl_table *table, int write,
7729 void __user *buffer, size_t *lenp,
7732 int old_period, old_runtime;
7733 static DEFINE_MUTEX(mutex);
7737 old_period = sysctl_sched_rt_period;
7738 old_runtime = sysctl_sched_rt_runtime;
7740 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7742 if (!ret && write) {
7743 ret = sched_rt_global_validate();
7747 ret = sched_rt_global_constraints();
7751 ret = sched_dl_global_constraints();
7755 sched_rt_do_global();
7756 sched_dl_do_global();
7760 sysctl_sched_rt_period = old_period;
7761 sysctl_sched_rt_runtime = old_runtime;
7763 mutex_unlock(&mutex);
7768 int sched_rr_handler(struct ctl_table *table, int write,
7769 void __user *buffer, size_t *lenp,
7773 static DEFINE_MUTEX(mutex);
7776 ret = proc_dointvec(table, write, buffer, lenp, ppos);
7777 /* make sure that internally we keep jiffies */
7778 /* also, writing zero resets timeslice to default */
7779 if (!ret && write) {
7780 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
7781 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
7783 mutex_unlock(&mutex);
7787 #ifdef CONFIG_CGROUP_SCHED
7789 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
7791 return css ? container_of(css, struct task_group, css) : NULL;
7794 static struct cgroup_subsys_state *
7795 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
7797 struct task_group *parent = css_tg(parent_css);
7798 struct task_group *tg;
7801 /* This is early initialization for the top cgroup */
7802 return &root_task_group.css;
7805 tg = sched_create_group(parent);
7807 return ERR_PTR(-ENOMEM);
7812 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
7814 struct task_group *tg = css_tg(css);
7815 struct task_group *parent = css_tg(css->parent);
7818 sched_online_group(tg, parent);
7822 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
7824 struct task_group *tg = css_tg(css);
7826 sched_destroy_group(tg);
7829 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
7831 struct task_group *tg = css_tg(css);
7833 sched_offline_group(tg);
7836 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
7837 struct cgroup_taskset *tset)
7839 struct task_struct *task;
7841 cgroup_taskset_for_each(task, tset) {
7842 #ifdef CONFIG_RT_GROUP_SCHED
7843 if (!sched_rt_can_attach(css_tg(css), task))
7846 /* We don't support RT-tasks being in separate groups */
7847 if (task->sched_class != &fair_sched_class)
7854 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
7855 struct cgroup_taskset *tset)
7857 struct task_struct *task;
7859 cgroup_taskset_for_each(task, tset)
7860 sched_move_task(task);
7863 static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
7864 struct cgroup_subsys_state *old_css,
7865 struct task_struct *task)
7868 * cgroup_exit() is called in the copy_process() failure path.
7869 * Ignore this case since the task hasn't ran yet, this avoids
7870 * trying to poke a half freed task state from generic code.
7872 if (!(task->flags & PF_EXITING))
7875 sched_move_task(task);
7878 #ifdef CONFIG_FAIR_GROUP_SCHED
7879 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
7880 struct cftype *cftype, u64 shareval)
7882 return sched_group_set_shares(css_tg(css), scale_load(shareval));
7885 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
7888 struct task_group *tg = css_tg(css);
7890 return (u64) scale_load_down(tg->shares);
7893 #ifdef CONFIG_CFS_BANDWIDTH
7894 static DEFINE_MUTEX(cfs_constraints_mutex);
7896 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
7897 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
7899 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
7901 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
7903 int i, ret = 0, runtime_enabled, runtime_was_enabled;
7904 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
7906 if (tg == &root_task_group)
7910 * Ensure we have at some amount of bandwidth every period. This is
7911 * to prevent reaching a state of large arrears when throttled via
7912 * entity_tick() resulting in prolonged exit starvation.
7914 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
7918 * Likewise, bound things on the otherside by preventing insane quota
7919 * periods. This also allows us to normalize in computing quota
7922 if (period > max_cfs_quota_period)
7926 * Prevent race between setting of cfs_rq->runtime_enabled and
7927 * unthrottle_offline_cfs_rqs().
7930 mutex_lock(&cfs_constraints_mutex);
7931 ret = __cfs_schedulable(tg, period, quota);
7935 runtime_enabled = quota != RUNTIME_INF;
7936 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
7938 * If we need to toggle cfs_bandwidth_used, off->on must occur
7939 * before making related changes, and on->off must occur afterwards
7941 if (runtime_enabled && !runtime_was_enabled)
7942 cfs_bandwidth_usage_inc();
7943 raw_spin_lock_irq(&cfs_b->lock);
7944 cfs_b->period = ns_to_ktime(period);
7945 cfs_b->quota = quota;
7947 __refill_cfs_bandwidth_runtime(cfs_b);
7948 /* restart the period timer (if active) to handle new period expiry */
7949 if (runtime_enabled && cfs_b->timer_active) {
7950 /* force a reprogram */
7951 __start_cfs_bandwidth(cfs_b, true);
7953 raw_spin_unlock_irq(&cfs_b->lock);
7955 for_each_online_cpu(i) {
7956 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
7957 struct rq *rq = cfs_rq->rq;
7959 raw_spin_lock_irq(&rq->lock);
7960 cfs_rq->runtime_enabled = runtime_enabled;
7961 cfs_rq->runtime_remaining = 0;
7963 if (cfs_rq->throttled)
7964 unthrottle_cfs_rq(cfs_rq);
7965 raw_spin_unlock_irq(&rq->lock);
7967 if (runtime_was_enabled && !runtime_enabled)
7968 cfs_bandwidth_usage_dec();
7970 mutex_unlock(&cfs_constraints_mutex);
7976 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
7980 period = ktime_to_ns(tg->cfs_bandwidth.period);
7981 if (cfs_quota_us < 0)
7982 quota = RUNTIME_INF;
7984 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
7986 return tg_set_cfs_bandwidth(tg, period, quota);
7989 long tg_get_cfs_quota(struct task_group *tg)
7993 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
7996 quota_us = tg->cfs_bandwidth.quota;
7997 do_div(quota_us, NSEC_PER_USEC);
8002 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
8006 period = (u64)cfs_period_us * NSEC_PER_USEC;
8007 quota = tg->cfs_bandwidth.quota;
8009 return tg_set_cfs_bandwidth(tg, period, quota);
8012 long tg_get_cfs_period(struct task_group *tg)
8016 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8017 do_div(cfs_period_us, NSEC_PER_USEC);
8019 return cfs_period_us;
8022 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
8025 return tg_get_cfs_quota(css_tg(css));
8028 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
8029 struct cftype *cftype, s64 cfs_quota_us)
8031 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8034 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
8037 return tg_get_cfs_period(css_tg(css));
8040 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
8041 struct cftype *cftype, u64 cfs_period_us)
8043 return tg_set_cfs_period(css_tg(css), cfs_period_us);
8046 struct cfs_schedulable_data {
8047 struct task_group *tg;
8052 * normalize group quota/period to be quota/max_period
8053 * note: units are usecs
8055 static u64 normalize_cfs_quota(struct task_group *tg,
8056 struct cfs_schedulable_data *d)
8064 period = tg_get_cfs_period(tg);
8065 quota = tg_get_cfs_quota(tg);
8068 /* note: these should typically be equivalent */
8069 if (quota == RUNTIME_INF || quota == -1)
8072 return to_ratio(period, quota);
8075 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8077 struct cfs_schedulable_data *d = data;
8078 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8079 s64 quota = 0, parent_quota = -1;
8082 quota = RUNTIME_INF;
8084 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8086 quota = normalize_cfs_quota(tg, d);
8087 parent_quota = parent_b->hierarchical_quota;
8090 * ensure max(child_quota) <= parent_quota, inherit when no
8093 if (quota == RUNTIME_INF)
8094 quota = parent_quota;
8095 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8098 cfs_b->hierarchical_quota = quota;
8103 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8106 struct cfs_schedulable_data data = {
8112 if (quota != RUNTIME_INF) {
8113 do_div(data.period, NSEC_PER_USEC);
8114 do_div(data.quota, NSEC_PER_USEC);
8118 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8124 static int cpu_stats_show(struct seq_file *sf, void *v)
8126 struct task_group *tg = css_tg(seq_css(sf));
8127 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8129 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8130 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8131 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8135 #endif /* CONFIG_CFS_BANDWIDTH */
8136 #endif /* CONFIG_FAIR_GROUP_SCHED */
8138 #ifdef CONFIG_RT_GROUP_SCHED
8139 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8140 struct cftype *cft, s64 val)
8142 return sched_group_set_rt_runtime(css_tg(css), val);
8145 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8148 return sched_group_rt_runtime(css_tg(css));
8151 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8152 struct cftype *cftype, u64 rt_period_us)
8154 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8157 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8160 return sched_group_rt_period(css_tg(css));
8162 #endif /* CONFIG_RT_GROUP_SCHED */
8164 static struct cftype cpu_files[] = {
8165 #ifdef CONFIG_FAIR_GROUP_SCHED
8168 .read_u64 = cpu_shares_read_u64,
8169 .write_u64 = cpu_shares_write_u64,
8172 #ifdef CONFIG_CFS_BANDWIDTH
8174 .name = "cfs_quota_us",
8175 .read_s64 = cpu_cfs_quota_read_s64,
8176 .write_s64 = cpu_cfs_quota_write_s64,
8179 .name = "cfs_period_us",
8180 .read_u64 = cpu_cfs_period_read_u64,
8181 .write_u64 = cpu_cfs_period_write_u64,
8185 .seq_show = cpu_stats_show,
8188 #ifdef CONFIG_RT_GROUP_SCHED
8190 .name = "rt_runtime_us",
8191 .read_s64 = cpu_rt_runtime_read,
8192 .write_s64 = cpu_rt_runtime_write,
8195 .name = "rt_period_us",
8196 .read_u64 = cpu_rt_period_read_uint,
8197 .write_u64 = cpu_rt_period_write_uint,
8203 struct cgroup_subsys cpu_cgrp_subsys = {
8204 .css_alloc = cpu_cgroup_css_alloc,
8205 .css_free = cpu_cgroup_css_free,
8206 .css_online = cpu_cgroup_css_online,
8207 .css_offline = cpu_cgroup_css_offline,
8208 .can_attach = cpu_cgroup_can_attach,
8209 .attach = cpu_cgroup_attach,
8210 .exit = cpu_cgroup_exit,
8211 .legacy_cftypes = cpu_files,
8215 #endif /* CONFIG_CGROUP_SCHED */
8217 void dump_cpu_task(int cpu)
8219 pr_info("Task dump for CPU %d:\n", cpu);
8220 sched_show_task(cpu_curr(cpu));