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 DEFINE_MUTEX(sched_domains_mutex);
94 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
96 static void update_rq_clock_task(struct rq *rq, s64 delta);
98 void update_rq_clock(struct rq *rq)
102 lockdep_assert_held(&rq->lock);
104 if (rq->clock_skip_update & RQCF_ACT_SKIP)
107 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
111 update_rq_clock_task(rq, delta);
115 * Debugging: various feature bits
118 #define SCHED_FEAT(name, enabled) \
119 (1UL << __SCHED_FEAT_##name) * enabled |
121 const_debug unsigned int sysctl_sched_features =
122 #include "features.h"
127 #ifdef CONFIG_SCHED_DEBUG
128 #define SCHED_FEAT(name, enabled) \
131 static const char * const sched_feat_names[] = {
132 #include "features.h"
137 static int sched_feat_show(struct seq_file *m, void *v)
141 for (i = 0; i < __SCHED_FEAT_NR; i++) {
142 if (!(sysctl_sched_features & (1UL << i)))
144 seq_printf(m, "%s ", sched_feat_names[i]);
151 #ifdef HAVE_JUMP_LABEL
153 #define jump_label_key__true STATIC_KEY_INIT_TRUE
154 #define jump_label_key__false STATIC_KEY_INIT_FALSE
156 #define SCHED_FEAT(name, enabled) \
157 jump_label_key__##enabled ,
159 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
160 #include "features.h"
165 static void sched_feat_disable(int i)
167 static_key_disable(&sched_feat_keys[i]);
170 static void sched_feat_enable(int i)
172 static_key_enable(&sched_feat_keys[i]);
175 static void sched_feat_disable(int i) { };
176 static void sched_feat_enable(int i) { };
177 #endif /* HAVE_JUMP_LABEL */
179 static int sched_feat_set(char *cmp)
184 if (strncmp(cmp, "NO_", 3) == 0) {
189 for (i = 0; i < __SCHED_FEAT_NR; i++) {
190 if (strcmp(cmp, sched_feat_names[i]) == 0) {
192 sysctl_sched_features &= ~(1UL << i);
193 sched_feat_disable(i);
195 sysctl_sched_features |= (1UL << i);
196 sched_feat_enable(i);
206 sched_feat_write(struct file *filp, const char __user *ubuf,
207 size_t cnt, loff_t *ppos)
217 if (copy_from_user(&buf, ubuf, cnt))
223 /* Ensure the static_key remains in a consistent state */
224 inode = file_inode(filp);
225 mutex_lock(&inode->i_mutex);
226 i = sched_feat_set(cmp);
227 mutex_unlock(&inode->i_mutex);
228 if (i == __SCHED_FEAT_NR)
236 static int sched_feat_open(struct inode *inode, struct file *filp)
238 return single_open(filp, sched_feat_show, NULL);
241 static const struct file_operations sched_feat_fops = {
242 .open = sched_feat_open,
243 .write = sched_feat_write,
246 .release = single_release,
249 static __init int sched_init_debug(void)
251 debugfs_create_file("sched_features", 0644, NULL, NULL,
256 late_initcall(sched_init_debug);
257 #endif /* CONFIG_SCHED_DEBUG */
260 * Number of tasks to iterate in a single balance run.
261 * Limited because this is done with IRQs disabled.
263 const_debug unsigned int sysctl_sched_nr_migrate = 32;
266 * period over which we average the RT time consumption, measured
271 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
274 * period over which we measure -rt task cpu usage in us.
277 unsigned int sysctl_sched_rt_period = 1000000;
279 __read_mostly int scheduler_running;
282 * part of the period that we allow rt tasks to run in us.
285 int sysctl_sched_rt_runtime = 950000;
287 /* cpus with isolated domains */
288 cpumask_var_t cpu_isolated_map;
291 * this_rq_lock - lock this runqueue and disable interrupts.
293 static struct rq *this_rq_lock(void)
300 raw_spin_lock(&rq->lock);
305 #ifdef CONFIG_SCHED_HRTICK
307 * Use HR-timers to deliver accurate preemption points.
310 static void hrtick_clear(struct rq *rq)
312 if (hrtimer_active(&rq->hrtick_timer))
313 hrtimer_cancel(&rq->hrtick_timer);
317 * High-resolution timer tick.
318 * Runs from hardirq context with interrupts disabled.
320 static enum hrtimer_restart hrtick(struct hrtimer *timer)
322 struct rq *rq = container_of(timer, struct rq, hrtick_timer);
324 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
326 raw_spin_lock(&rq->lock);
328 rq->curr->sched_class->task_tick(rq, rq->curr, 1);
329 raw_spin_unlock(&rq->lock);
331 return HRTIMER_NORESTART;
336 static void __hrtick_restart(struct rq *rq)
338 struct hrtimer *timer = &rq->hrtick_timer;
340 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
344 * called from hardirq (IPI) context
346 static void __hrtick_start(void *arg)
350 raw_spin_lock(&rq->lock);
351 __hrtick_restart(rq);
352 rq->hrtick_csd_pending = 0;
353 raw_spin_unlock(&rq->lock);
357 * Called to set the hrtick timer state.
359 * called with rq->lock held and irqs disabled
361 void hrtick_start(struct rq *rq, u64 delay)
363 struct hrtimer *timer = &rq->hrtick_timer;
368 * Don't schedule slices shorter than 10000ns, that just
369 * doesn't make sense and can cause timer DoS.
371 delta = max_t(s64, delay, 10000LL);
372 time = ktime_add_ns(timer->base->get_time(), delta);
374 hrtimer_set_expires(timer, time);
376 if (rq == this_rq()) {
377 __hrtick_restart(rq);
378 } else if (!rq->hrtick_csd_pending) {
379 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
380 rq->hrtick_csd_pending = 1;
385 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
387 int cpu = (int)(long)hcpu;
390 case CPU_UP_CANCELED:
391 case CPU_UP_CANCELED_FROZEN:
392 case CPU_DOWN_PREPARE:
393 case CPU_DOWN_PREPARE_FROZEN:
395 case CPU_DEAD_FROZEN:
396 hrtick_clear(cpu_rq(cpu));
403 static __init void init_hrtick(void)
405 hotcpu_notifier(hotplug_hrtick, 0);
409 * Called to set the hrtick timer state.
411 * called with rq->lock held and irqs disabled
413 void hrtick_start(struct rq *rq, u64 delay)
416 * Don't schedule slices shorter than 10000ns, that just
417 * doesn't make sense. Rely on vruntime for fairness.
419 delay = max_t(u64, delay, 10000LL);
420 hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
421 HRTIMER_MODE_REL_PINNED);
424 static inline void init_hrtick(void)
427 #endif /* CONFIG_SMP */
429 static void init_rq_hrtick(struct rq *rq)
432 rq->hrtick_csd_pending = 0;
434 rq->hrtick_csd.flags = 0;
435 rq->hrtick_csd.func = __hrtick_start;
436 rq->hrtick_csd.info = rq;
439 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
440 rq->hrtick_timer.function = hrtick;
442 #else /* CONFIG_SCHED_HRTICK */
443 static inline void hrtick_clear(struct rq *rq)
447 static inline void init_rq_hrtick(struct rq *rq)
451 static inline void init_hrtick(void)
454 #endif /* CONFIG_SCHED_HRTICK */
457 * cmpxchg based fetch_or, macro so it works for different integer types
459 #define fetch_or(ptr, val) \
460 ({ typeof(*(ptr)) __old, __val = *(ptr); \
462 __old = cmpxchg((ptr), __val, __val | (val)); \
463 if (__old == __val) \
470 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
472 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
473 * this avoids any races wrt polling state changes and thereby avoids
476 static bool set_nr_and_not_polling(struct task_struct *p)
478 struct thread_info *ti = task_thread_info(p);
479 return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
483 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
485 * If this returns true, then the idle task promises to call
486 * sched_ttwu_pending() and reschedule soon.
488 static bool set_nr_if_polling(struct task_struct *p)
490 struct thread_info *ti = task_thread_info(p);
491 typeof(ti->flags) old, val = READ_ONCE(ti->flags);
494 if (!(val & _TIF_POLLING_NRFLAG))
496 if (val & _TIF_NEED_RESCHED)
498 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
507 static bool set_nr_and_not_polling(struct task_struct *p)
509 set_tsk_need_resched(p);
514 static bool set_nr_if_polling(struct task_struct *p)
521 void wake_q_add(struct wake_q_head *head, struct task_struct *task)
523 struct wake_q_node *node = &task->wake_q;
526 * Atomically grab the task, if ->wake_q is !nil already it means
527 * its already queued (either by us or someone else) and will get the
528 * wakeup due to that.
530 * This cmpxchg() implies a full barrier, which pairs with the write
531 * barrier implied by the wakeup in wake_up_list().
533 if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL))
536 get_task_struct(task);
539 * The head is context local, there can be no concurrency.
542 head->lastp = &node->next;
545 void wake_up_q(struct wake_q_head *head)
547 struct wake_q_node *node = head->first;
549 while (node != WAKE_Q_TAIL) {
550 struct task_struct *task;
552 task = container_of(node, struct task_struct, wake_q);
554 /* task can safely be re-inserted now */
556 task->wake_q.next = NULL;
559 * wake_up_process() implies a wmb() to pair with the queueing
560 * in wake_q_add() so as not to miss wakeups.
562 wake_up_process(task);
563 put_task_struct(task);
568 * resched_curr - mark rq's current task 'to be rescheduled now'.
570 * On UP this means the setting of the need_resched flag, on SMP it
571 * might also involve a cross-CPU call to trigger the scheduler on
574 void resched_curr(struct rq *rq)
576 struct task_struct *curr = rq->curr;
579 lockdep_assert_held(&rq->lock);
581 if (test_tsk_need_resched(curr))
586 if (cpu == smp_processor_id()) {
587 set_tsk_need_resched(curr);
588 set_preempt_need_resched();
592 if (set_nr_and_not_polling(curr))
593 smp_send_reschedule(cpu);
595 trace_sched_wake_idle_without_ipi(cpu);
598 void resched_cpu(int cpu)
600 struct rq *rq = cpu_rq(cpu);
603 if (!raw_spin_trylock_irqsave(&rq->lock, flags))
606 raw_spin_unlock_irqrestore(&rq->lock, flags);
610 #ifdef CONFIG_NO_HZ_COMMON
612 * In the semi idle case, use the nearest busy cpu for migrating timers
613 * from an idle cpu. This is good for power-savings.
615 * We don't do similar optimization for completely idle system, as
616 * selecting an idle cpu will add more delays to the timers than intended
617 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
619 int get_nohz_timer_target(void)
621 int i, cpu = smp_processor_id();
622 struct sched_domain *sd;
624 if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
628 for_each_domain(cpu, sd) {
629 for_each_cpu(i, sched_domain_span(sd)) {
630 if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
637 if (!is_housekeeping_cpu(cpu))
638 cpu = housekeeping_any_cpu();
644 * When add_timer_on() enqueues a timer into the timer wheel of an
645 * idle CPU then this timer might expire before the next timer event
646 * which is scheduled to wake up that CPU. In case of a completely
647 * idle system the next event might even be infinite time into the
648 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
649 * leaves the inner idle loop so the newly added timer is taken into
650 * account when the CPU goes back to idle and evaluates the timer
651 * wheel for the next timer event.
653 static void wake_up_idle_cpu(int cpu)
655 struct rq *rq = cpu_rq(cpu);
657 if (cpu == smp_processor_id())
660 if (set_nr_and_not_polling(rq->idle))
661 smp_send_reschedule(cpu);
663 trace_sched_wake_idle_without_ipi(cpu);
666 static bool wake_up_full_nohz_cpu(int cpu)
669 * We just need the target to call irq_exit() and re-evaluate
670 * the next tick. The nohz full kick at least implies that.
671 * If needed we can still optimize that later with an
674 if (tick_nohz_full_cpu(cpu)) {
675 if (cpu != smp_processor_id() ||
676 tick_nohz_tick_stopped())
677 tick_nohz_full_kick_cpu(cpu);
684 void wake_up_nohz_cpu(int cpu)
686 if (!wake_up_full_nohz_cpu(cpu))
687 wake_up_idle_cpu(cpu);
690 static inline bool got_nohz_idle_kick(void)
692 int cpu = smp_processor_id();
694 if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)))
697 if (idle_cpu(cpu) && !need_resched())
701 * We can't run Idle Load Balance on this CPU for this time so we
702 * cancel it and clear NOHZ_BALANCE_KICK
704 clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
708 #else /* CONFIG_NO_HZ_COMMON */
710 static inline bool got_nohz_idle_kick(void)
715 #endif /* CONFIG_NO_HZ_COMMON */
717 #ifdef CONFIG_NO_HZ_FULL
718 bool sched_can_stop_tick(void)
721 * FIFO realtime policy runs the highest priority task. Other runnable
722 * tasks are of a lower priority. The scheduler tick does nothing.
724 if (current->policy == SCHED_FIFO)
728 * Round-robin realtime tasks time slice with other tasks at the same
729 * realtime priority. Is this task the only one at this priority?
731 if (current->policy == SCHED_RR) {
732 struct sched_rt_entity *rt_se = ¤t->rt;
734 return rt_se->run_list.prev == rt_se->run_list.next;
738 * More than one running task need preemption.
739 * nr_running update is assumed to be visible
740 * after IPI is sent from wakers.
742 if (this_rq()->nr_running > 1)
747 #endif /* CONFIG_NO_HZ_FULL */
749 void sched_avg_update(struct rq *rq)
751 s64 period = sched_avg_period();
753 while ((s64)(rq_clock(rq) - rq->age_stamp) > period) {
755 * Inline assembly required to prevent the compiler
756 * optimising this loop into a divmod call.
757 * See __iter_div_u64_rem() for another example of this.
759 asm("" : "+rm" (rq->age_stamp));
760 rq->age_stamp += period;
765 #endif /* CONFIG_SMP */
767 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
768 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
770 * Iterate task_group tree rooted at *from, calling @down when first entering a
771 * node and @up when leaving it for the final time.
773 * Caller must hold rcu_lock or sufficient equivalent.
775 int walk_tg_tree_from(struct task_group *from,
776 tg_visitor down, tg_visitor up, void *data)
778 struct task_group *parent, *child;
784 ret = (*down)(parent, data);
787 list_for_each_entry_rcu(child, &parent->children, siblings) {
794 ret = (*up)(parent, data);
795 if (ret || parent == from)
799 parent = parent->parent;
806 int tg_nop(struct task_group *tg, void *data)
812 static void set_load_weight(struct task_struct *p)
814 int prio = p->static_prio - MAX_RT_PRIO;
815 struct load_weight *load = &p->se.load;
818 * SCHED_IDLE tasks get minimal weight:
820 if (idle_policy(p->policy)) {
821 load->weight = scale_load(WEIGHT_IDLEPRIO);
822 load->inv_weight = WMULT_IDLEPRIO;
826 load->weight = scale_load(prio_to_weight[prio]);
827 load->inv_weight = prio_to_wmult[prio];
830 static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
833 if (!(flags & ENQUEUE_RESTORE))
834 sched_info_queued(rq, p);
835 p->sched_class->enqueue_task(rq, p, flags);
838 static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
841 if (!(flags & DEQUEUE_SAVE))
842 sched_info_dequeued(rq, p);
843 p->sched_class->dequeue_task(rq, p, flags);
846 void activate_task(struct rq *rq, struct task_struct *p, int flags)
848 if (task_contributes_to_load(p))
849 rq->nr_uninterruptible--;
851 enqueue_task(rq, p, flags);
854 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
856 if (task_contributes_to_load(p))
857 rq->nr_uninterruptible++;
859 dequeue_task(rq, p, flags);
862 static void update_rq_clock_task(struct rq *rq, s64 delta)
865 * In theory, the compile should just see 0 here, and optimize out the call
866 * to sched_rt_avg_update. But I don't trust it...
868 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
869 s64 steal = 0, irq_delta = 0;
871 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
872 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
875 * Since irq_time is only updated on {soft,}irq_exit, we might run into
876 * this case when a previous update_rq_clock() happened inside a
879 * When this happens, we stop ->clock_task and only update the
880 * prev_irq_time stamp to account for the part that fit, so that a next
881 * update will consume the rest. This ensures ->clock_task is
884 * It does however cause some slight miss-attribution of {soft,}irq
885 * time, a more accurate solution would be to update the irq_time using
886 * the current rq->clock timestamp, except that would require using
889 if (irq_delta > delta)
892 rq->prev_irq_time += irq_delta;
895 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
896 if (static_key_false((¶virt_steal_rq_enabled))) {
897 steal = paravirt_steal_clock(cpu_of(rq));
898 steal -= rq->prev_steal_time_rq;
900 if (unlikely(steal > delta))
903 rq->prev_steal_time_rq += steal;
908 rq->clock_task += delta;
910 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
911 if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
912 sched_rt_avg_update(rq, irq_delta + steal);
916 void sched_set_stop_task(int cpu, struct task_struct *stop)
918 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
919 struct task_struct *old_stop = cpu_rq(cpu)->stop;
923 * Make it appear like a SCHED_FIFO task, its something
924 * userspace knows about and won't get confused about.
926 * Also, it will make PI more or less work without too
927 * much confusion -- but then, stop work should not
928 * rely on PI working anyway.
930 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m);
932 stop->sched_class = &stop_sched_class;
935 cpu_rq(cpu)->stop = stop;
939 * Reset it back to a normal scheduling class so that
940 * it can die in pieces.
942 old_stop->sched_class = &rt_sched_class;
947 * __normal_prio - return the priority that is based on the static prio
949 static inline int __normal_prio(struct task_struct *p)
951 return p->static_prio;
955 * Calculate the expected normal priority: i.e. priority
956 * without taking RT-inheritance into account. Might be
957 * boosted by interactivity modifiers. Changes upon fork,
958 * setprio syscalls, and whenever the interactivity
959 * estimator recalculates.
961 static inline int normal_prio(struct task_struct *p)
965 if (task_has_dl_policy(p))
966 prio = MAX_DL_PRIO-1;
967 else if (task_has_rt_policy(p))
968 prio = MAX_RT_PRIO-1 - p->rt_priority;
970 prio = __normal_prio(p);
975 * Calculate the current priority, i.e. the priority
976 * taken into account by the scheduler. This value might
977 * be boosted by RT tasks, or might be boosted by
978 * interactivity modifiers. Will be RT if the task got
979 * RT-boosted. If not then it returns p->normal_prio.
981 static int effective_prio(struct task_struct *p)
983 p->normal_prio = normal_prio(p);
985 * If we are RT tasks or we were boosted to RT priority,
986 * keep the priority unchanged. Otherwise, update priority
987 * to the normal priority:
989 if (!rt_prio(p->prio))
990 return p->normal_prio;
995 * task_curr - is this task currently executing on a CPU?
996 * @p: the task in question.
998 * Return: 1 if the task is currently executing. 0 otherwise.
1000 inline int task_curr(const struct task_struct *p)
1002 return cpu_curr(task_cpu(p)) == p;
1006 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
1007 * use the balance_callback list if you want balancing.
1009 * this means any call to check_class_changed() must be followed by a call to
1010 * balance_callback().
1012 static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1013 const struct sched_class *prev_class,
1016 if (prev_class != p->sched_class) {
1017 if (prev_class->switched_from)
1018 prev_class->switched_from(rq, p);
1020 p->sched_class->switched_to(rq, p);
1021 } else if (oldprio != p->prio || dl_task(p))
1022 p->sched_class->prio_changed(rq, p, oldprio);
1025 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
1027 const struct sched_class *class;
1029 if (p->sched_class == rq->curr->sched_class) {
1030 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
1032 for_each_class(class) {
1033 if (class == rq->curr->sched_class)
1035 if (class == p->sched_class) {
1043 * A queue event has occurred, and we're going to schedule. In
1044 * this case, we can save a useless back to back clock update.
1046 if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
1047 rq_clock_skip_update(rq, true);
1052 * This is how migration works:
1054 * 1) we invoke migration_cpu_stop() on the target CPU using
1056 * 2) stopper starts to run (implicitly forcing the migrated thread
1058 * 3) it checks whether the migrated task is still in the wrong runqueue.
1059 * 4) if it's in the wrong runqueue then the migration thread removes
1060 * it and puts it into the right queue.
1061 * 5) stopper completes and stop_one_cpu() returns and the migration
1066 * move_queued_task - move a queued task to new rq.
1068 * Returns (locked) new rq. Old rq's lock is released.
1070 static struct rq *move_queued_task(struct rq *rq, struct task_struct *p, int new_cpu)
1072 lockdep_assert_held(&rq->lock);
1074 dequeue_task(rq, p, 0);
1075 p->on_rq = TASK_ON_RQ_MIGRATING;
1076 set_task_cpu(p, new_cpu);
1077 raw_spin_unlock(&rq->lock);
1079 rq = cpu_rq(new_cpu);
1081 raw_spin_lock(&rq->lock);
1082 BUG_ON(task_cpu(p) != new_cpu);
1083 p->on_rq = TASK_ON_RQ_QUEUED;
1084 enqueue_task(rq, p, 0);
1085 check_preempt_curr(rq, p, 0);
1090 struct migration_arg {
1091 struct task_struct *task;
1096 * Move (not current) task off this cpu, onto dest cpu. We're doing
1097 * this because either it can't run here any more (set_cpus_allowed()
1098 * away from this CPU, or CPU going down), or because we're
1099 * attempting to rebalance this task on exec (sched_exec).
1101 * So we race with normal scheduler movements, but that's OK, as long
1102 * as the task is no longer on this CPU.
1104 static struct rq *__migrate_task(struct rq *rq, struct task_struct *p, int dest_cpu)
1106 if (unlikely(!cpu_active(dest_cpu)))
1109 /* Affinity changed (again). */
1110 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1113 rq = move_queued_task(rq, p, dest_cpu);
1119 * migration_cpu_stop - this will be executed by a highprio stopper thread
1120 * and performs thread migration by bumping thread off CPU then
1121 * 'pushing' onto another runqueue.
1123 static int migration_cpu_stop(void *data)
1125 struct migration_arg *arg = data;
1126 struct task_struct *p = arg->task;
1127 struct rq *rq = this_rq();
1130 * The original target cpu might have gone down and we might
1131 * be on another cpu but it doesn't matter.
1133 local_irq_disable();
1135 * We need to explicitly wake pending tasks before running
1136 * __migrate_task() such that we will not miss enforcing cpus_allowed
1137 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1139 sched_ttwu_pending();
1141 raw_spin_lock(&p->pi_lock);
1142 raw_spin_lock(&rq->lock);
1144 * If task_rq(p) != rq, it cannot be migrated here, because we're
1145 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1146 * we're holding p->pi_lock.
1148 if (task_rq(p) == rq && task_on_rq_queued(p))
1149 rq = __migrate_task(rq, p, arg->dest_cpu);
1150 raw_spin_unlock(&rq->lock);
1151 raw_spin_unlock(&p->pi_lock);
1158 * sched_class::set_cpus_allowed must do the below, but is not required to
1159 * actually call this function.
1161 void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
1163 cpumask_copy(&p->cpus_allowed, new_mask);
1164 p->nr_cpus_allowed = cpumask_weight(new_mask);
1167 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
1169 struct rq *rq = task_rq(p);
1170 bool queued, running;
1172 lockdep_assert_held(&p->pi_lock);
1174 queued = task_on_rq_queued(p);
1175 running = task_current(rq, p);
1179 * Because __kthread_bind() calls this on blocked tasks without
1182 lockdep_assert_held(&rq->lock);
1183 dequeue_task(rq, p, DEQUEUE_SAVE);
1186 put_prev_task(rq, p);
1188 p->sched_class->set_cpus_allowed(p, new_mask);
1191 p->sched_class->set_curr_task(rq);
1193 enqueue_task(rq, p, ENQUEUE_RESTORE);
1197 * Change a given task's CPU affinity. Migrate the thread to a
1198 * proper CPU and schedule it away if the CPU it's executing on
1199 * is removed from the allowed bitmask.
1201 * NOTE: the caller must have a valid reference to the task, the
1202 * task must not exit() & deallocate itself prematurely. The
1203 * call is not atomic; no spinlocks may be held.
1205 static int __set_cpus_allowed_ptr(struct task_struct *p,
1206 const struct cpumask *new_mask, bool check)
1208 unsigned long flags;
1210 unsigned int dest_cpu;
1213 rq = task_rq_lock(p, &flags);
1216 * Must re-check here, to close a race against __kthread_bind(),
1217 * sched_setaffinity() is not guaranteed to observe the flag.
1219 if (check && (p->flags & PF_NO_SETAFFINITY)) {
1224 if (cpumask_equal(&p->cpus_allowed, new_mask))
1227 if (!cpumask_intersects(new_mask, cpu_active_mask)) {
1232 do_set_cpus_allowed(p, new_mask);
1234 /* Can the task run on the task's current CPU? If so, we're done */
1235 if (cpumask_test_cpu(task_cpu(p), new_mask))
1238 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
1239 if (task_running(rq, p) || p->state == TASK_WAKING) {
1240 struct migration_arg arg = { p, dest_cpu };
1241 /* Need help from migration thread: drop lock and wait. */
1242 task_rq_unlock(rq, p, &flags);
1243 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
1244 tlb_migrate_finish(p->mm);
1246 } else if (task_on_rq_queued(p)) {
1248 * OK, since we're going to drop the lock immediately
1249 * afterwards anyway.
1251 lockdep_unpin_lock(&rq->lock);
1252 rq = move_queued_task(rq, p, dest_cpu);
1253 lockdep_pin_lock(&rq->lock);
1256 task_rq_unlock(rq, p, &flags);
1261 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
1263 return __set_cpus_allowed_ptr(p, new_mask, false);
1265 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
1267 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1269 #ifdef CONFIG_SCHED_DEBUG
1271 * We should never call set_task_cpu() on a blocked task,
1272 * ttwu() will sort out the placement.
1274 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1277 #ifdef CONFIG_LOCKDEP
1279 * The caller should hold either p->pi_lock or rq->lock, when changing
1280 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1282 * sched_move_task() holds both and thus holding either pins the cgroup,
1285 * Furthermore, all task_rq users should acquire both locks, see
1288 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1289 lockdep_is_held(&task_rq(p)->lock)));
1293 trace_sched_migrate_task(p, new_cpu);
1295 if (task_cpu(p) != new_cpu) {
1296 if (p->sched_class->migrate_task_rq)
1297 p->sched_class->migrate_task_rq(p);
1298 p->se.nr_migrations++;
1299 perf_event_task_migrate(p);
1302 __set_task_cpu(p, new_cpu);
1305 static void __migrate_swap_task(struct task_struct *p, int cpu)
1307 if (task_on_rq_queued(p)) {
1308 struct rq *src_rq, *dst_rq;
1310 src_rq = task_rq(p);
1311 dst_rq = cpu_rq(cpu);
1313 deactivate_task(src_rq, p, 0);
1314 set_task_cpu(p, cpu);
1315 activate_task(dst_rq, p, 0);
1316 check_preempt_curr(dst_rq, p, 0);
1319 * Task isn't running anymore; make it appear like we migrated
1320 * it before it went to sleep. This means on wakeup we make the
1321 * previous cpu our targer instead of where it really is.
1327 struct migration_swap_arg {
1328 struct task_struct *src_task, *dst_task;
1329 int src_cpu, dst_cpu;
1332 static int migrate_swap_stop(void *data)
1334 struct migration_swap_arg *arg = data;
1335 struct rq *src_rq, *dst_rq;
1338 if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
1341 src_rq = cpu_rq(arg->src_cpu);
1342 dst_rq = cpu_rq(arg->dst_cpu);
1344 double_raw_lock(&arg->src_task->pi_lock,
1345 &arg->dst_task->pi_lock);
1346 double_rq_lock(src_rq, dst_rq);
1348 if (task_cpu(arg->dst_task) != arg->dst_cpu)
1351 if (task_cpu(arg->src_task) != arg->src_cpu)
1354 if (!cpumask_test_cpu(arg->dst_cpu, tsk_cpus_allowed(arg->src_task)))
1357 if (!cpumask_test_cpu(arg->src_cpu, tsk_cpus_allowed(arg->dst_task)))
1360 __migrate_swap_task(arg->src_task, arg->dst_cpu);
1361 __migrate_swap_task(arg->dst_task, arg->src_cpu);
1366 double_rq_unlock(src_rq, dst_rq);
1367 raw_spin_unlock(&arg->dst_task->pi_lock);
1368 raw_spin_unlock(&arg->src_task->pi_lock);
1374 * Cross migrate two tasks
1376 int migrate_swap(struct task_struct *cur, struct task_struct *p)
1378 struct migration_swap_arg arg;
1381 arg = (struct migration_swap_arg){
1383 .src_cpu = task_cpu(cur),
1385 .dst_cpu = task_cpu(p),
1388 if (arg.src_cpu == arg.dst_cpu)
1392 * These three tests are all lockless; this is OK since all of them
1393 * will be re-checked with proper locks held further down the line.
1395 if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
1398 if (!cpumask_test_cpu(arg.dst_cpu, tsk_cpus_allowed(arg.src_task)))
1401 if (!cpumask_test_cpu(arg.src_cpu, tsk_cpus_allowed(arg.dst_task)))
1404 trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
1405 ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
1412 * wait_task_inactive - wait for a thread to unschedule.
1414 * If @match_state is nonzero, it's the @p->state value just checked and
1415 * not expected to change. If it changes, i.e. @p might have woken up,
1416 * then return zero. When we succeed in waiting for @p to be off its CPU,
1417 * we return a positive number (its total switch count). If a second call
1418 * a short while later returns the same number, the caller can be sure that
1419 * @p has remained unscheduled the whole time.
1421 * The caller must ensure that the task *will* unschedule sometime soon,
1422 * else this function might spin for a *long* time. This function can't
1423 * be called with interrupts off, or it may introduce deadlock with
1424 * smp_call_function() if an IPI is sent by the same process we are
1425 * waiting to become inactive.
1427 unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1429 unsigned long flags;
1430 int running, queued;
1436 * We do the initial early heuristics without holding
1437 * any task-queue locks at all. We'll only try to get
1438 * the runqueue lock when things look like they will
1444 * If the task is actively running on another CPU
1445 * still, just relax and busy-wait without holding
1448 * NOTE! Since we don't hold any locks, it's not
1449 * even sure that "rq" stays as the right runqueue!
1450 * But we don't care, since "task_running()" will
1451 * return false if the runqueue has changed and p
1452 * is actually now running somewhere else!
1454 while (task_running(rq, p)) {
1455 if (match_state && unlikely(p->state != match_state))
1461 * Ok, time to look more closely! We need the rq
1462 * lock now, to be *sure*. If we're wrong, we'll
1463 * just go back and repeat.
1465 rq = task_rq_lock(p, &flags);
1466 trace_sched_wait_task(p);
1467 running = task_running(rq, p);
1468 queued = task_on_rq_queued(p);
1470 if (!match_state || p->state == match_state)
1471 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1472 task_rq_unlock(rq, p, &flags);
1475 * If it changed from the expected state, bail out now.
1477 if (unlikely(!ncsw))
1481 * Was it really running after all now that we
1482 * checked with the proper locks actually held?
1484 * Oops. Go back and try again..
1486 if (unlikely(running)) {
1492 * It's not enough that it's not actively running,
1493 * it must be off the runqueue _entirely_, and not
1496 * So if it was still runnable (but just not actively
1497 * running right now), it's preempted, and we should
1498 * yield - it could be a while.
1500 if (unlikely(queued)) {
1501 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1503 set_current_state(TASK_UNINTERRUPTIBLE);
1504 schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1509 * Ahh, all good. It wasn't running, and it wasn't
1510 * runnable, which means that it will never become
1511 * running in the future either. We're all done!
1520 * kick_process - kick a running thread to enter/exit the kernel
1521 * @p: the to-be-kicked thread
1523 * Cause a process which is running on another CPU to enter
1524 * kernel-mode, without any delay. (to get signals handled.)
1526 * NOTE: this function doesn't have to take the runqueue lock,
1527 * because all it wants to ensure is that the remote task enters
1528 * the kernel. If the IPI races and the task has been migrated
1529 * to another CPU then no harm is done and the purpose has been
1532 void kick_process(struct task_struct *p)
1538 if ((cpu != smp_processor_id()) && task_curr(p))
1539 smp_send_reschedule(cpu);
1542 EXPORT_SYMBOL_GPL(kick_process);
1545 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1547 static int select_fallback_rq(int cpu, struct task_struct *p)
1549 int nid = cpu_to_node(cpu);
1550 const struct cpumask *nodemask = NULL;
1551 enum { cpuset, possible, fail } state = cpuset;
1555 * If the node that the cpu is on has been offlined, cpu_to_node()
1556 * will return -1. There is no cpu on the node, and we should
1557 * select the cpu on the other node.
1560 nodemask = cpumask_of_node(nid);
1562 /* Look for allowed, online CPU in same node. */
1563 for_each_cpu(dest_cpu, nodemask) {
1564 if (!cpu_online(dest_cpu))
1566 if (!cpu_active(dest_cpu))
1568 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1574 /* Any allowed, online CPU? */
1575 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1576 if (!cpu_online(dest_cpu))
1578 if (!cpu_active(dest_cpu))
1583 /* No more Mr. Nice Guy. */
1586 if (IS_ENABLED(CONFIG_CPUSETS)) {
1587 cpuset_cpus_allowed_fallback(p);
1593 do_set_cpus_allowed(p, cpu_possible_mask);
1604 if (state != cpuset) {
1606 * Don't tell them about moving exiting tasks or
1607 * kernel threads (both mm NULL), since they never
1610 if (p->mm && printk_ratelimit()) {
1611 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1612 task_pid_nr(p), p->comm, cpu);
1620 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1623 int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
1625 lockdep_assert_held(&p->pi_lock);
1627 if (p->nr_cpus_allowed > 1)
1628 cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
1631 * In order not to call set_task_cpu() on a blocking task we need
1632 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1635 * Since this is common to all placement strategies, this lives here.
1637 * [ this allows ->select_task() to simply return task_cpu(p) and
1638 * not worry about this generic constraint ]
1640 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1642 cpu = select_fallback_rq(task_cpu(p), p);
1647 static void update_avg(u64 *avg, u64 sample)
1649 s64 diff = sample - *avg;
1655 static inline int __set_cpus_allowed_ptr(struct task_struct *p,
1656 const struct cpumask *new_mask, bool check)
1658 return set_cpus_allowed_ptr(p, new_mask);
1661 #endif /* CONFIG_SMP */
1664 ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1666 #ifdef CONFIG_SCHEDSTATS
1667 struct rq *rq = this_rq();
1670 int this_cpu = smp_processor_id();
1672 if (cpu == this_cpu) {
1673 schedstat_inc(rq, ttwu_local);
1674 schedstat_inc(p, se.statistics.nr_wakeups_local);
1676 struct sched_domain *sd;
1678 schedstat_inc(p, se.statistics.nr_wakeups_remote);
1680 for_each_domain(this_cpu, sd) {
1681 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1682 schedstat_inc(sd, ttwu_wake_remote);
1689 if (wake_flags & WF_MIGRATED)
1690 schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1692 #endif /* CONFIG_SMP */
1694 schedstat_inc(rq, ttwu_count);
1695 schedstat_inc(p, se.statistics.nr_wakeups);
1697 if (wake_flags & WF_SYNC)
1698 schedstat_inc(p, se.statistics.nr_wakeups_sync);
1700 #endif /* CONFIG_SCHEDSTATS */
1703 static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1705 activate_task(rq, p, en_flags);
1706 p->on_rq = TASK_ON_RQ_QUEUED;
1708 /* if a worker is waking up, notify workqueue */
1709 if (p->flags & PF_WQ_WORKER)
1710 wq_worker_waking_up(p, cpu_of(rq));
1714 * Mark the task runnable and perform wakeup-preemption.
1717 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1719 check_preempt_curr(rq, p, wake_flags);
1720 p->state = TASK_RUNNING;
1721 trace_sched_wakeup(p);
1724 if (p->sched_class->task_woken) {
1726 * Our task @p is fully woken up and running; so its safe to
1727 * drop the rq->lock, hereafter rq is only used for statistics.
1729 lockdep_unpin_lock(&rq->lock);
1730 p->sched_class->task_woken(rq, p);
1731 lockdep_pin_lock(&rq->lock);
1734 if (rq->idle_stamp) {
1735 u64 delta = rq_clock(rq) - rq->idle_stamp;
1736 u64 max = 2*rq->max_idle_balance_cost;
1738 update_avg(&rq->avg_idle, delta);
1740 if (rq->avg_idle > max)
1749 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1751 lockdep_assert_held(&rq->lock);
1754 if (p->sched_contributes_to_load)
1755 rq->nr_uninterruptible--;
1758 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1759 ttwu_do_wakeup(rq, p, wake_flags);
1763 * Called in case the task @p isn't fully descheduled from its runqueue,
1764 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1765 * since all we need to do is flip p->state to TASK_RUNNING, since
1766 * the task is still ->on_rq.
1768 static int ttwu_remote(struct task_struct *p, int wake_flags)
1773 rq = __task_rq_lock(p);
1774 if (task_on_rq_queued(p)) {
1775 /* check_preempt_curr() may use rq clock */
1776 update_rq_clock(rq);
1777 ttwu_do_wakeup(rq, p, wake_flags);
1780 __task_rq_unlock(rq);
1786 void sched_ttwu_pending(void)
1788 struct rq *rq = this_rq();
1789 struct llist_node *llist = llist_del_all(&rq->wake_list);
1790 struct task_struct *p;
1791 unsigned long flags;
1796 raw_spin_lock_irqsave(&rq->lock, flags);
1797 lockdep_pin_lock(&rq->lock);
1800 p = llist_entry(llist, struct task_struct, wake_entry);
1801 llist = llist_next(llist);
1802 ttwu_do_activate(rq, p, 0);
1805 lockdep_unpin_lock(&rq->lock);
1806 raw_spin_unlock_irqrestore(&rq->lock, flags);
1809 void scheduler_ipi(void)
1812 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1813 * TIF_NEED_RESCHED remotely (for the first time) will also send
1816 preempt_fold_need_resched();
1818 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1822 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1823 * traditionally all their work was done from the interrupt return
1824 * path. Now that we actually do some work, we need to make sure
1827 * Some archs already do call them, luckily irq_enter/exit nest
1830 * Arguably we should visit all archs and update all handlers,
1831 * however a fair share of IPIs are still resched only so this would
1832 * somewhat pessimize the simple resched case.
1835 sched_ttwu_pending();
1838 * Check if someone kicked us for doing the nohz idle load balance.
1840 if (unlikely(got_nohz_idle_kick())) {
1841 this_rq()->idle_balance = 1;
1842 raise_softirq_irqoff(SCHED_SOFTIRQ);
1847 static void ttwu_queue_remote(struct task_struct *p, int cpu)
1849 struct rq *rq = cpu_rq(cpu);
1851 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
1852 if (!set_nr_if_polling(rq->idle))
1853 smp_send_reschedule(cpu);
1855 trace_sched_wake_idle_without_ipi(cpu);
1859 void wake_up_if_idle(int cpu)
1861 struct rq *rq = cpu_rq(cpu);
1862 unsigned long flags;
1866 if (!is_idle_task(rcu_dereference(rq->curr)))
1869 if (set_nr_if_polling(rq->idle)) {
1870 trace_sched_wake_idle_without_ipi(cpu);
1872 raw_spin_lock_irqsave(&rq->lock, flags);
1873 if (is_idle_task(rq->curr))
1874 smp_send_reschedule(cpu);
1875 /* Else cpu is not in idle, do nothing here */
1876 raw_spin_unlock_irqrestore(&rq->lock, flags);
1883 bool cpus_share_cache(int this_cpu, int that_cpu)
1885 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1887 #endif /* CONFIG_SMP */
1889 static void ttwu_queue(struct task_struct *p, int cpu)
1891 struct rq *rq = cpu_rq(cpu);
1893 #if defined(CONFIG_SMP)
1894 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1895 sched_clock_cpu(cpu); /* sync clocks x-cpu */
1896 ttwu_queue_remote(p, cpu);
1901 raw_spin_lock(&rq->lock);
1902 lockdep_pin_lock(&rq->lock);
1903 ttwu_do_activate(rq, p, 0);
1904 lockdep_unpin_lock(&rq->lock);
1905 raw_spin_unlock(&rq->lock);
1909 * try_to_wake_up - wake up a thread
1910 * @p: the thread to be awakened
1911 * @state: the mask of task states that can be woken
1912 * @wake_flags: wake modifier flags (WF_*)
1914 * Put it on the run-queue if it's not already there. The "current"
1915 * thread is always on the run-queue (except when the actual
1916 * re-schedule is in progress), and as such you're allowed to do
1917 * the simpler "current->state = TASK_RUNNING" to mark yourself
1918 * runnable without the overhead of this.
1920 * Return: %true if @p was woken up, %false if it was already running.
1921 * or @state didn't match @p's state.
1924 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1926 unsigned long flags;
1927 int cpu, success = 0;
1930 * If we are going to wake up a thread waiting for CONDITION we
1931 * need to ensure that CONDITION=1 done by the caller can not be
1932 * reordered with p->state check below. This pairs with mb() in
1933 * set_current_state() the waiting thread does.
1935 smp_mb__before_spinlock();
1936 raw_spin_lock_irqsave(&p->pi_lock, flags);
1937 if (!(p->state & state))
1940 trace_sched_waking(p);
1942 success = 1; /* we're going to change ->state */
1945 if (p->on_rq && ttwu_remote(p, wake_flags))
1950 * If the owning (remote) cpu is still in the middle of schedule() with
1951 * this task as prev, wait until its done referencing the task.
1956 * Pairs with the smp_wmb() in finish_lock_switch().
1960 p->sched_contributes_to_load = !!task_contributes_to_load(p);
1961 p->state = TASK_WAKING;
1963 if (p->sched_class->task_waking)
1964 p->sched_class->task_waking(p);
1966 cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
1967 if (task_cpu(p) != cpu) {
1968 wake_flags |= WF_MIGRATED;
1969 set_task_cpu(p, cpu);
1971 #endif /* CONFIG_SMP */
1975 ttwu_stat(p, cpu, wake_flags);
1977 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1983 * try_to_wake_up_local - try to wake up a local task with rq lock held
1984 * @p: the thread to be awakened
1986 * Put @p on the run-queue if it's not already there. The caller must
1987 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1990 static void try_to_wake_up_local(struct task_struct *p)
1992 struct rq *rq = task_rq(p);
1994 if (WARN_ON_ONCE(rq != this_rq()) ||
1995 WARN_ON_ONCE(p == current))
1998 lockdep_assert_held(&rq->lock);
2000 if (!raw_spin_trylock(&p->pi_lock)) {
2002 * This is OK, because current is on_cpu, which avoids it being
2003 * picked for load-balance and preemption/IRQs are still
2004 * disabled avoiding further scheduler activity on it and we've
2005 * not yet picked a replacement task.
2007 lockdep_unpin_lock(&rq->lock);
2008 raw_spin_unlock(&rq->lock);
2009 raw_spin_lock(&p->pi_lock);
2010 raw_spin_lock(&rq->lock);
2011 lockdep_pin_lock(&rq->lock);
2014 if (!(p->state & TASK_NORMAL))
2017 trace_sched_waking(p);
2019 if (!task_on_rq_queued(p))
2020 ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2022 ttwu_do_wakeup(rq, p, 0);
2023 ttwu_stat(p, smp_processor_id(), 0);
2025 raw_spin_unlock(&p->pi_lock);
2029 * wake_up_process - Wake up a specific process
2030 * @p: The process to be woken up.
2032 * Attempt to wake up the nominated process and move it to the set of runnable
2035 * Return: 1 if the process was woken up, 0 if it was already running.
2037 * It may be assumed that this function implies a write memory barrier before
2038 * changing the task state if and only if any tasks are woken up.
2040 int wake_up_process(struct task_struct *p)
2042 return try_to_wake_up(p, TASK_NORMAL, 0);
2044 EXPORT_SYMBOL(wake_up_process);
2046 int wake_up_state(struct task_struct *p, unsigned int state)
2048 return try_to_wake_up(p, state, 0);
2052 * This function clears the sched_dl_entity static params.
2054 void __dl_clear_params(struct task_struct *p)
2056 struct sched_dl_entity *dl_se = &p->dl;
2058 dl_se->dl_runtime = 0;
2059 dl_se->dl_deadline = 0;
2060 dl_se->dl_period = 0;
2064 dl_se->dl_throttled = 0;
2066 dl_se->dl_yielded = 0;
2070 * Perform scheduler related setup for a newly forked process p.
2071 * p is forked by current.
2073 * __sched_fork() is basic setup used by init_idle() too:
2075 static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
2080 p->se.exec_start = 0;
2081 p->se.sum_exec_runtime = 0;
2082 p->se.prev_sum_exec_runtime = 0;
2083 p->se.nr_migrations = 0;
2085 INIT_LIST_HEAD(&p->se.group_node);
2087 #ifdef CONFIG_SCHEDSTATS
2088 memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2091 RB_CLEAR_NODE(&p->dl.rb_node);
2092 init_dl_task_timer(&p->dl);
2093 __dl_clear_params(p);
2095 INIT_LIST_HEAD(&p->rt.run_list);
2097 #ifdef CONFIG_PREEMPT_NOTIFIERS
2098 INIT_HLIST_HEAD(&p->preempt_notifiers);
2101 #ifdef CONFIG_NUMA_BALANCING
2102 if (p->mm && atomic_read(&p->mm->mm_users) == 1) {
2103 p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay);
2104 p->mm->numa_scan_seq = 0;
2107 if (clone_flags & CLONE_VM)
2108 p->numa_preferred_nid = current->numa_preferred_nid;
2110 p->numa_preferred_nid = -1;
2112 p->node_stamp = 0ULL;
2113 p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
2114 p->numa_scan_period = sysctl_numa_balancing_scan_delay;
2115 p->numa_work.next = &p->numa_work;
2116 p->numa_faults = NULL;
2117 p->last_task_numa_placement = 0;
2118 p->last_sum_exec_runtime = 0;
2120 p->numa_group = NULL;
2121 #endif /* CONFIG_NUMA_BALANCING */
2124 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
2126 #ifdef CONFIG_NUMA_BALANCING
2128 void set_numabalancing_state(bool enabled)
2131 static_branch_enable(&sched_numa_balancing);
2133 static_branch_disable(&sched_numa_balancing);
2136 #ifdef CONFIG_PROC_SYSCTL
2137 int sysctl_numa_balancing(struct ctl_table *table, int write,
2138 void __user *buffer, size_t *lenp, loff_t *ppos)
2142 int state = static_branch_likely(&sched_numa_balancing);
2144 if (write && !capable(CAP_SYS_ADMIN))
2149 err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2153 set_numabalancing_state(state);
2160 * fork()/clone()-time setup:
2162 int sched_fork(unsigned long clone_flags, struct task_struct *p)
2164 unsigned long flags;
2165 int cpu = get_cpu();
2167 __sched_fork(clone_flags, p);
2169 * We mark the process as running here. This guarantees that
2170 * nobody will actually run it, and a signal or other external
2171 * event cannot wake it up and insert it on the runqueue either.
2173 p->state = TASK_RUNNING;
2176 * Make sure we do not leak PI boosting priority to the child.
2178 p->prio = current->normal_prio;
2181 * Revert to default priority/policy on fork if requested.
2183 if (unlikely(p->sched_reset_on_fork)) {
2184 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
2185 p->policy = SCHED_NORMAL;
2186 p->static_prio = NICE_TO_PRIO(0);
2188 } else if (PRIO_TO_NICE(p->static_prio) < 0)
2189 p->static_prio = NICE_TO_PRIO(0);
2191 p->prio = p->normal_prio = __normal_prio(p);
2195 * We don't need the reset flag anymore after the fork. It has
2196 * fulfilled its duty:
2198 p->sched_reset_on_fork = 0;
2201 if (dl_prio(p->prio)) {
2204 } else if (rt_prio(p->prio)) {
2205 p->sched_class = &rt_sched_class;
2207 p->sched_class = &fair_sched_class;
2210 if (p->sched_class->task_fork)
2211 p->sched_class->task_fork(p);
2214 * The child is not yet in the pid-hash so no cgroup attach races,
2215 * and the cgroup is pinned to this child due to cgroup_fork()
2216 * is ran before sched_fork().
2218 * Silence PROVE_RCU.
2220 raw_spin_lock_irqsave(&p->pi_lock, flags);
2221 set_task_cpu(p, cpu);
2222 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2224 #ifdef CONFIG_SCHED_INFO
2225 if (likely(sched_info_on()))
2226 memset(&p->sched_info, 0, sizeof(p->sched_info));
2228 #if defined(CONFIG_SMP)
2231 init_task_preempt_count(p);
2233 plist_node_init(&p->pushable_tasks, MAX_PRIO);
2234 RB_CLEAR_NODE(&p->pushable_dl_tasks);
2241 unsigned long to_ratio(u64 period, u64 runtime)
2243 if (runtime == RUNTIME_INF)
2247 * Doing this here saves a lot of checks in all
2248 * the calling paths, and returning zero seems
2249 * safe for them anyway.
2254 return div64_u64(runtime << 20, period);
2258 inline struct dl_bw *dl_bw_of(int i)
2260 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2261 "sched RCU must be held");
2262 return &cpu_rq(i)->rd->dl_bw;
2265 static inline int dl_bw_cpus(int i)
2267 struct root_domain *rd = cpu_rq(i)->rd;
2270 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2271 "sched RCU must be held");
2272 for_each_cpu_and(i, rd->span, cpu_active_mask)
2278 inline struct dl_bw *dl_bw_of(int i)
2280 return &cpu_rq(i)->dl.dl_bw;
2283 static inline int dl_bw_cpus(int i)
2290 * We must be sure that accepting a new task (or allowing changing the
2291 * parameters of an existing one) is consistent with the bandwidth
2292 * constraints. If yes, this function also accordingly updates the currently
2293 * allocated bandwidth to reflect the new situation.
2295 * This function is called while holding p's rq->lock.
2297 * XXX we should delay bw change until the task's 0-lag point, see
2300 static int dl_overflow(struct task_struct *p, int policy,
2301 const struct sched_attr *attr)
2304 struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
2305 u64 period = attr->sched_period ?: attr->sched_deadline;
2306 u64 runtime = attr->sched_runtime;
2307 u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
2310 if (new_bw == p->dl.dl_bw)
2314 * Either if a task, enters, leave, or stays -deadline but changes
2315 * its parameters, we may need to update accordingly the total
2316 * allocated bandwidth of the container.
2318 raw_spin_lock(&dl_b->lock);
2319 cpus = dl_bw_cpus(task_cpu(p));
2320 if (dl_policy(policy) && !task_has_dl_policy(p) &&
2321 !__dl_overflow(dl_b, cpus, 0, new_bw)) {
2322 __dl_add(dl_b, new_bw);
2324 } else if (dl_policy(policy) && task_has_dl_policy(p) &&
2325 !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
2326 __dl_clear(dl_b, p->dl.dl_bw);
2327 __dl_add(dl_b, new_bw);
2329 } else if (!dl_policy(policy) && task_has_dl_policy(p)) {
2330 __dl_clear(dl_b, p->dl.dl_bw);
2333 raw_spin_unlock(&dl_b->lock);
2338 extern void init_dl_bw(struct dl_bw *dl_b);
2341 * wake_up_new_task - wake up a newly created task for the first time.
2343 * This function will do some initial scheduler statistics housekeeping
2344 * that must be done for every newly created context, then puts the task
2345 * on the runqueue and wakes it.
2347 void wake_up_new_task(struct task_struct *p)
2349 unsigned long flags;
2352 raw_spin_lock_irqsave(&p->pi_lock, flags);
2353 /* Initialize new task's runnable average */
2354 init_entity_runnable_average(&p->se);
2357 * Fork balancing, do it here and not earlier because:
2358 * - cpus_allowed can change in the fork path
2359 * - any previously selected cpu might disappear through hotplug
2361 set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
2364 rq = __task_rq_lock(p);
2365 activate_task(rq, p, 0);
2366 p->on_rq = TASK_ON_RQ_QUEUED;
2367 trace_sched_wakeup_new(p);
2368 check_preempt_curr(rq, p, WF_FORK);
2370 if (p->sched_class->task_woken) {
2372 * Nothing relies on rq->lock after this, so its fine to
2375 lockdep_unpin_lock(&rq->lock);
2376 p->sched_class->task_woken(rq, p);
2377 lockdep_pin_lock(&rq->lock);
2380 task_rq_unlock(rq, p, &flags);
2383 #ifdef CONFIG_PREEMPT_NOTIFIERS
2385 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
2387 void preempt_notifier_inc(void)
2389 static_key_slow_inc(&preempt_notifier_key);
2391 EXPORT_SYMBOL_GPL(preempt_notifier_inc);
2393 void preempt_notifier_dec(void)
2395 static_key_slow_dec(&preempt_notifier_key);
2397 EXPORT_SYMBOL_GPL(preempt_notifier_dec);
2400 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2401 * @notifier: notifier struct to register
2403 void preempt_notifier_register(struct preempt_notifier *notifier)
2405 if (!static_key_false(&preempt_notifier_key))
2406 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2408 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers);
2410 EXPORT_SYMBOL_GPL(preempt_notifier_register);
2413 * preempt_notifier_unregister - no longer interested in preemption notifications
2414 * @notifier: notifier struct to unregister
2416 * This is *not* safe to call from within a preemption notifier.
2418 void preempt_notifier_unregister(struct preempt_notifier *notifier)
2420 hlist_del(¬ifier->link);
2422 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2424 static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
2426 struct preempt_notifier *notifier;
2428 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2429 notifier->ops->sched_in(notifier, raw_smp_processor_id());
2432 static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2434 if (static_key_false(&preempt_notifier_key))
2435 __fire_sched_in_preempt_notifiers(curr);
2439 __fire_sched_out_preempt_notifiers(struct task_struct *curr,
2440 struct task_struct *next)
2442 struct preempt_notifier *notifier;
2444 hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
2445 notifier->ops->sched_out(notifier, next);
2448 static __always_inline void
2449 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2450 struct task_struct *next)
2452 if (static_key_false(&preempt_notifier_key))
2453 __fire_sched_out_preempt_notifiers(curr, next);
2456 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2458 static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2463 fire_sched_out_preempt_notifiers(struct task_struct *curr,
2464 struct task_struct *next)
2468 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2471 * prepare_task_switch - prepare to switch tasks
2472 * @rq: the runqueue preparing to switch
2473 * @prev: the current task that is being switched out
2474 * @next: the task we are going to switch to.
2476 * This is called with the rq lock held and interrupts off. It must
2477 * be paired with a subsequent finish_task_switch after the context
2480 * prepare_task_switch sets up locking and calls architecture specific
2484 prepare_task_switch(struct rq *rq, struct task_struct *prev,
2485 struct task_struct *next)
2487 sched_info_switch(rq, prev, next);
2488 perf_event_task_sched_out(prev, next);
2489 fire_sched_out_preempt_notifiers(prev, next);
2490 prepare_lock_switch(rq, next);
2491 prepare_arch_switch(next);
2495 * finish_task_switch - clean up after a task-switch
2496 * @prev: the thread we just switched away from.
2498 * finish_task_switch must be called after the context switch, paired
2499 * with a prepare_task_switch call before the context switch.
2500 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2501 * and do any other architecture-specific cleanup actions.
2503 * Note that we may have delayed dropping an mm in context_switch(). If
2504 * so, we finish that here outside of the runqueue lock. (Doing it
2505 * with the lock held can cause deadlocks; see schedule() for
2508 * The context switch have flipped the stack from under us and restored the
2509 * local variables which were saved when this task called schedule() in the
2510 * past. prev == current is still correct but we need to recalculate this_rq
2511 * because prev may have moved to another CPU.
2513 static struct rq *finish_task_switch(struct task_struct *prev)
2514 __releases(rq->lock)
2516 struct rq *rq = this_rq();
2517 struct mm_struct *mm = rq->prev_mm;
2521 * The previous task will have left us with a preempt_count of 2
2522 * because it left us after:
2525 * preempt_disable(); // 1
2527 * raw_spin_lock_irq(&rq->lock) // 2
2529 * Also, see FORK_PREEMPT_COUNT.
2531 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
2532 "corrupted preempt_count: %s/%d/0x%x\n",
2533 current->comm, current->pid, preempt_count()))
2534 preempt_count_set(FORK_PREEMPT_COUNT);
2539 * A task struct has one reference for the use as "current".
2540 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2541 * schedule one last time. The schedule call will never return, and
2542 * the scheduled task must drop that reference.
2544 * We must observe prev->state before clearing prev->on_cpu (in
2545 * finish_lock_switch), otherwise a concurrent wakeup can get prev
2546 * running on another CPU and we could rave with its RUNNING -> DEAD
2547 * transition, resulting in a double drop.
2549 prev_state = prev->state;
2550 vtime_task_switch(prev);
2551 perf_event_task_sched_in(prev, current);
2552 finish_lock_switch(rq, prev);
2553 finish_arch_post_lock_switch();
2555 fire_sched_in_preempt_notifiers(current);
2558 if (unlikely(prev_state == TASK_DEAD)) {
2559 if (prev->sched_class->task_dead)
2560 prev->sched_class->task_dead(prev);
2563 * Remove function-return probe instances associated with this
2564 * task and put them back on the free list.
2566 kprobe_flush_task(prev);
2567 put_task_struct(prev);
2570 tick_nohz_task_switch();
2576 /* rq->lock is NOT held, but preemption is disabled */
2577 static void __balance_callback(struct rq *rq)
2579 struct callback_head *head, *next;
2580 void (*func)(struct rq *rq);
2581 unsigned long flags;
2583 raw_spin_lock_irqsave(&rq->lock, flags);
2584 head = rq->balance_callback;
2585 rq->balance_callback = NULL;
2587 func = (void (*)(struct rq *))head->func;
2594 raw_spin_unlock_irqrestore(&rq->lock, flags);
2597 static inline void balance_callback(struct rq *rq)
2599 if (unlikely(rq->balance_callback))
2600 __balance_callback(rq);
2605 static inline void balance_callback(struct rq *rq)
2612 * schedule_tail - first thing a freshly forked thread must call.
2613 * @prev: the thread we just switched away from.
2615 asmlinkage __visible void schedule_tail(struct task_struct *prev)
2616 __releases(rq->lock)
2621 * New tasks start with FORK_PREEMPT_COUNT, see there and
2622 * finish_task_switch() for details.
2624 * finish_task_switch() will drop rq->lock() and lower preempt_count
2625 * and the preempt_enable() will end up enabling preemption (on
2626 * PREEMPT_COUNT kernels).
2629 rq = finish_task_switch(prev);
2630 balance_callback(rq);
2633 if (current->set_child_tid)
2634 put_user(task_pid_vnr(current), current->set_child_tid);
2638 * context_switch - switch to the new MM and the new thread's register state.
2640 static inline struct rq *
2641 context_switch(struct rq *rq, struct task_struct *prev,
2642 struct task_struct *next)
2644 struct mm_struct *mm, *oldmm;
2646 prepare_task_switch(rq, prev, next);
2649 oldmm = prev->active_mm;
2651 * For paravirt, this is coupled with an exit in switch_to to
2652 * combine the page table reload and the switch backend into
2655 arch_start_context_switch(prev);
2658 next->active_mm = oldmm;
2659 atomic_inc(&oldmm->mm_count);
2660 enter_lazy_tlb(oldmm, next);
2662 switch_mm(oldmm, mm, next);
2665 prev->active_mm = NULL;
2666 rq->prev_mm = oldmm;
2669 * Since the runqueue lock will be released by the next
2670 * task (which is an invalid locking op but in the case
2671 * of the scheduler it's an obvious special-case), so we
2672 * do an early lockdep release here:
2674 lockdep_unpin_lock(&rq->lock);
2675 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2677 /* Here we just switch the register state and the stack. */
2678 switch_to(prev, next, prev);
2681 return finish_task_switch(prev);
2685 * nr_running and nr_context_switches:
2687 * externally visible scheduler statistics: current number of runnable
2688 * threads, total number of context switches performed since bootup.
2690 unsigned long nr_running(void)
2692 unsigned long i, sum = 0;
2694 for_each_online_cpu(i)
2695 sum += cpu_rq(i)->nr_running;
2701 * Check if only the current task is running on the cpu.
2703 * Caution: this function does not check that the caller has disabled
2704 * preemption, thus the result might have a time-of-check-to-time-of-use
2705 * race. The caller is responsible to use it correctly, for example:
2707 * - from a non-preemptable section (of course)
2709 * - from a thread that is bound to a single CPU
2711 * - in a loop with very short iterations (e.g. a polling loop)
2713 bool single_task_running(void)
2715 return raw_rq()->nr_running == 1;
2717 EXPORT_SYMBOL(single_task_running);
2719 unsigned long long nr_context_switches(void)
2722 unsigned long long sum = 0;
2724 for_each_possible_cpu(i)
2725 sum += cpu_rq(i)->nr_switches;
2730 unsigned long nr_iowait(void)
2732 unsigned long i, sum = 0;
2734 for_each_possible_cpu(i)
2735 sum += atomic_read(&cpu_rq(i)->nr_iowait);
2740 unsigned long nr_iowait_cpu(int cpu)
2742 struct rq *this = cpu_rq(cpu);
2743 return atomic_read(&this->nr_iowait);
2746 void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
2748 struct rq *rq = this_rq();
2749 *nr_waiters = atomic_read(&rq->nr_iowait);
2750 *load = rq->load.weight;
2756 * sched_exec - execve() is a valuable balancing opportunity, because at
2757 * this point the task has the smallest effective memory and cache footprint.
2759 void sched_exec(void)
2761 struct task_struct *p = current;
2762 unsigned long flags;
2765 raw_spin_lock_irqsave(&p->pi_lock, flags);
2766 dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
2767 if (dest_cpu == smp_processor_id())
2770 if (likely(cpu_active(dest_cpu))) {
2771 struct migration_arg arg = { p, dest_cpu };
2773 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2774 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2778 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2783 DEFINE_PER_CPU(struct kernel_stat, kstat);
2784 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2786 EXPORT_PER_CPU_SYMBOL(kstat);
2787 EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2790 * Return accounted runtime for the task.
2791 * In case the task is currently running, return the runtime plus current's
2792 * pending runtime that have not been accounted yet.
2794 unsigned long long task_sched_runtime(struct task_struct *p)
2796 unsigned long flags;
2800 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2802 * 64-bit doesn't need locks to atomically read a 64bit value.
2803 * So we have a optimization chance when the task's delta_exec is 0.
2804 * Reading ->on_cpu is racy, but this is ok.
2806 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2807 * If we race with it entering cpu, unaccounted time is 0. This is
2808 * indistinguishable from the read occurring a few cycles earlier.
2809 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2810 * been accounted, so we're correct here as well.
2812 if (!p->on_cpu || !task_on_rq_queued(p))
2813 return p->se.sum_exec_runtime;
2816 rq = task_rq_lock(p, &flags);
2818 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2819 * project cycles that may never be accounted to this
2820 * thread, breaking clock_gettime().
2822 if (task_current(rq, p) && task_on_rq_queued(p)) {
2823 update_rq_clock(rq);
2824 p->sched_class->update_curr(rq);
2826 ns = p->se.sum_exec_runtime;
2827 task_rq_unlock(rq, p, &flags);
2833 * This function gets called by the timer code, with HZ frequency.
2834 * We call it with interrupts disabled.
2836 void scheduler_tick(void)
2838 int cpu = smp_processor_id();
2839 struct rq *rq = cpu_rq(cpu);
2840 struct task_struct *curr = rq->curr;
2844 raw_spin_lock(&rq->lock);
2845 update_rq_clock(rq);
2846 curr->sched_class->task_tick(rq, curr, 0);
2847 update_cpu_load_active(rq);
2848 calc_global_load_tick(rq);
2849 raw_spin_unlock(&rq->lock);
2851 perf_event_task_tick();
2854 rq->idle_balance = idle_cpu(cpu);
2855 trigger_load_balance(rq);
2857 rq_last_tick_reset(rq);
2860 #ifdef CONFIG_NO_HZ_FULL
2862 * scheduler_tick_max_deferment
2864 * Keep at least one tick per second when a single
2865 * active task is running because the scheduler doesn't
2866 * yet completely support full dynticks environment.
2868 * This makes sure that uptime, CFS vruntime, load
2869 * balancing, etc... continue to move forward, even
2870 * with a very low granularity.
2872 * Return: Maximum deferment in nanoseconds.
2874 u64 scheduler_tick_max_deferment(void)
2876 struct rq *rq = this_rq();
2877 unsigned long next, now = READ_ONCE(jiffies);
2879 next = rq->last_sched_tick + HZ;
2881 if (time_before_eq(next, now))
2884 return jiffies_to_nsecs(next - now);
2888 notrace unsigned long get_parent_ip(unsigned long addr)
2890 if (in_lock_functions(addr)) {
2891 addr = CALLER_ADDR2;
2892 if (in_lock_functions(addr))
2893 addr = CALLER_ADDR3;
2898 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2899 defined(CONFIG_PREEMPT_TRACER))
2901 void preempt_count_add(int val)
2903 #ifdef CONFIG_DEBUG_PREEMPT
2907 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2910 __preempt_count_add(val);
2911 #ifdef CONFIG_DEBUG_PREEMPT
2913 * Spinlock count overflowing soon?
2915 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2918 if (preempt_count() == val) {
2919 unsigned long ip = get_parent_ip(CALLER_ADDR1);
2920 #ifdef CONFIG_DEBUG_PREEMPT
2921 current->preempt_disable_ip = ip;
2923 trace_preempt_off(CALLER_ADDR0, ip);
2926 EXPORT_SYMBOL(preempt_count_add);
2927 NOKPROBE_SYMBOL(preempt_count_add);
2929 void preempt_count_sub(int val)
2931 #ifdef CONFIG_DEBUG_PREEMPT
2935 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2938 * Is the spinlock portion underflowing?
2940 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2941 !(preempt_count() & PREEMPT_MASK)))
2945 if (preempt_count() == val)
2946 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2947 __preempt_count_sub(val);
2949 EXPORT_SYMBOL(preempt_count_sub);
2950 NOKPROBE_SYMBOL(preempt_count_sub);
2955 * Print scheduling while atomic bug:
2957 static noinline void __schedule_bug(struct task_struct *prev)
2959 if (oops_in_progress)
2962 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2963 prev->comm, prev->pid, preempt_count());
2965 debug_show_held_locks(prev);
2967 if (irqs_disabled())
2968 print_irqtrace_events(prev);
2969 #ifdef CONFIG_DEBUG_PREEMPT
2970 if (in_atomic_preempt_off()) {
2971 pr_err("Preemption disabled at:");
2972 print_ip_sym(current->preempt_disable_ip);
2977 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
2981 * Various schedule()-time debugging checks and statistics:
2983 static inline void schedule_debug(struct task_struct *prev)
2985 #ifdef CONFIG_SCHED_STACK_END_CHECK
2986 BUG_ON(task_stack_end_corrupted(prev));
2989 if (unlikely(in_atomic_preempt_off())) {
2990 __schedule_bug(prev);
2991 preempt_count_set(PREEMPT_DISABLED);
2995 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2997 schedstat_inc(this_rq(), sched_count);
3001 * Pick up the highest-prio task:
3003 static inline struct task_struct *
3004 pick_next_task(struct rq *rq, struct task_struct *prev)
3006 const struct sched_class *class = &fair_sched_class;
3007 struct task_struct *p;
3010 * Optimization: we know that if all tasks are in
3011 * the fair class we can call that function directly:
3013 if (likely(prev->sched_class == class &&
3014 rq->nr_running == rq->cfs.h_nr_running)) {
3015 p = fair_sched_class.pick_next_task(rq, prev);
3016 if (unlikely(p == RETRY_TASK))
3019 /* assumes fair_sched_class->next == idle_sched_class */
3021 p = idle_sched_class.pick_next_task(rq, prev);
3027 for_each_class(class) {
3028 p = class->pick_next_task(rq, prev);
3030 if (unlikely(p == RETRY_TASK))
3036 BUG(); /* the idle class will always have a runnable task */
3040 * __schedule() is the main scheduler function.
3042 * The main means of driving the scheduler and thus entering this function are:
3044 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3046 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3047 * paths. For example, see arch/x86/entry_64.S.
3049 * To drive preemption between tasks, the scheduler sets the flag in timer
3050 * interrupt handler scheduler_tick().
3052 * 3. Wakeups don't really cause entry into schedule(). They add a
3053 * task to the run-queue and that's it.
3055 * Now, if the new task added to the run-queue preempts the current
3056 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3057 * called on the nearest possible occasion:
3059 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3061 * - in syscall or exception context, at the next outmost
3062 * preempt_enable(). (this might be as soon as the wake_up()'s
3065 * - in IRQ context, return from interrupt-handler to
3066 * preemptible context
3068 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3071 * - cond_resched() call
3072 * - explicit schedule() call
3073 * - return from syscall or exception to user-space
3074 * - return from interrupt-handler to user-space
3076 * WARNING: must be called with preemption disabled!
3078 static void __sched notrace __schedule(bool preempt)
3080 struct task_struct *prev, *next;
3081 unsigned long *switch_count;
3085 cpu = smp_processor_id();
3087 rcu_note_context_switch();
3091 * do_exit() calls schedule() with preemption disabled as an exception;
3092 * however we must fix that up, otherwise the next task will see an
3093 * inconsistent (higher) preempt count.
3095 * It also avoids the below schedule_debug() test from complaining
3098 if (unlikely(prev->state == TASK_DEAD))
3099 preempt_enable_no_resched_notrace();
3101 schedule_debug(prev);
3103 if (sched_feat(HRTICK))
3107 * Make sure that signal_pending_state()->signal_pending() below
3108 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3109 * done by the caller to avoid the race with signal_wake_up().
3111 smp_mb__before_spinlock();
3112 raw_spin_lock_irq(&rq->lock);
3113 lockdep_pin_lock(&rq->lock);
3115 rq->clock_skip_update <<= 1; /* promote REQ to ACT */
3117 switch_count = &prev->nivcsw;
3118 if (!preempt && prev->state) {
3119 if (unlikely(signal_pending_state(prev->state, prev))) {
3120 prev->state = TASK_RUNNING;
3122 deactivate_task(rq, prev, DEQUEUE_SLEEP);
3126 * If a worker went to sleep, notify and ask workqueue
3127 * whether it wants to wake up a task to maintain
3130 if (prev->flags & PF_WQ_WORKER) {
3131 struct task_struct *to_wakeup;
3133 to_wakeup = wq_worker_sleeping(prev, cpu);
3135 try_to_wake_up_local(to_wakeup);
3138 switch_count = &prev->nvcsw;
3141 if (task_on_rq_queued(prev))
3142 update_rq_clock(rq);
3144 next = pick_next_task(rq, prev);
3145 clear_tsk_need_resched(prev);
3146 clear_preempt_need_resched();
3147 rq->clock_skip_update = 0;
3149 if (likely(prev != next)) {
3154 trace_sched_switch(preempt, prev, next);
3155 rq = context_switch(rq, prev, next); /* unlocks the rq */
3158 lockdep_unpin_lock(&rq->lock);
3159 raw_spin_unlock_irq(&rq->lock);
3162 balance_callback(rq);
3165 static inline void sched_submit_work(struct task_struct *tsk)
3167 if (!tsk->state || tsk_is_pi_blocked(tsk))
3170 * If we are going to sleep and we have plugged IO queued,
3171 * make sure to submit it to avoid deadlocks.
3173 if (blk_needs_flush_plug(tsk))
3174 blk_schedule_flush_plug(tsk);
3177 asmlinkage __visible void __sched schedule(void)
3179 struct task_struct *tsk = current;
3181 sched_submit_work(tsk);
3185 sched_preempt_enable_no_resched();
3186 } while (need_resched());
3188 EXPORT_SYMBOL(schedule);
3190 #ifdef CONFIG_CONTEXT_TRACKING
3191 asmlinkage __visible void __sched schedule_user(void)
3194 * If we come here after a random call to set_need_resched(),
3195 * or we have been woken up remotely but the IPI has not yet arrived,
3196 * we haven't yet exited the RCU idle mode. Do it here manually until
3197 * we find a better solution.
3199 * NB: There are buggy callers of this function. Ideally we
3200 * should warn if prev_state != CONTEXT_USER, but that will trigger
3201 * too frequently to make sense yet.
3203 enum ctx_state prev_state = exception_enter();
3205 exception_exit(prev_state);
3210 * schedule_preempt_disabled - called with preemption disabled
3212 * Returns with preemption disabled. Note: preempt_count must be 1
3214 void __sched schedule_preempt_disabled(void)
3216 sched_preempt_enable_no_resched();
3221 static void __sched notrace preempt_schedule_common(void)
3224 preempt_disable_notrace();
3226 preempt_enable_no_resched_notrace();
3229 * Check again in case we missed a preemption opportunity
3230 * between schedule and now.
3232 } while (need_resched());
3235 #ifdef CONFIG_PREEMPT
3237 * this is the entry point to schedule() from in-kernel preemption
3238 * off of preempt_enable. Kernel preemptions off return from interrupt
3239 * occur there and call schedule directly.
3241 asmlinkage __visible void __sched notrace preempt_schedule(void)
3244 * If there is a non-zero preempt_count or interrupts are disabled,
3245 * we do not want to preempt the current task. Just return..
3247 if (likely(!preemptible()))
3250 preempt_schedule_common();
3252 NOKPROBE_SYMBOL(preempt_schedule);
3253 EXPORT_SYMBOL(preempt_schedule);
3256 * preempt_schedule_notrace - preempt_schedule called by tracing
3258 * The tracing infrastructure uses preempt_enable_notrace to prevent
3259 * recursion and tracing preempt enabling caused by the tracing
3260 * infrastructure itself. But as tracing can happen in areas coming
3261 * from userspace or just about to enter userspace, a preempt enable
3262 * can occur before user_exit() is called. This will cause the scheduler
3263 * to be called when the system is still in usermode.
3265 * To prevent this, the preempt_enable_notrace will use this function
3266 * instead of preempt_schedule() to exit user context if needed before
3267 * calling the scheduler.
3269 asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
3271 enum ctx_state prev_ctx;
3273 if (likely(!preemptible()))
3277 preempt_disable_notrace();
3279 * Needs preempt disabled in case user_exit() is traced
3280 * and the tracer calls preempt_enable_notrace() causing
3281 * an infinite recursion.
3283 prev_ctx = exception_enter();
3285 exception_exit(prev_ctx);
3287 preempt_enable_no_resched_notrace();
3288 } while (need_resched());
3290 EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
3292 #endif /* CONFIG_PREEMPT */
3295 * this is the entry point to schedule() from kernel preemption
3296 * off of irq context.
3297 * Note, that this is called and return with irqs disabled. This will
3298 * protect us against recursive calling from irq.
3300 asmlinkage __visible void __sched preempt_schedule_irq(void)
3302 enum ctx_state prev_state;
3304 /* Catch callers which need to be fixed */
3305 BUG_ON(preempt_count() || !irqs_disabled());
3307 prev_state = exception_enter();
3313 local_irq_disable();
3314 sched_preempt_enable_no_resched();
3315 } while (need_resched());
3317 exception_exit(prev_state);
3320 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3323 return try_to_wake_up(curr->private, mode, wake_flags);
3325 EXPORT_SYMBOL(default_wake_function);
3327 #ifdef CONFIG_RT_MUTEXES
3330 * rt_mutex_setprio - set the current priority of a task
3332 * @prio: prio value (kernel-internal form)
3334 * This function changes the 'effective' priority of a task. It does
3335 * not touch ->normal_prio like __setscheduler().
3337 * Used by the rt_mutex code to implement priority inheritance
3338 * logic. Call site only calls if the priority of the task changed.
3340 void rt_mutex_setprio(struct task_struct *p, int prio)
3342 int oldprio, queued, running, enqueue_flag = ENQUEUE_RESTORE;
3344 const struct sched_class *prev_class;
3346 BUG_ON(prio > MAX_PRIO);
3348 rq = __task_rq_lock(p);
3351 * Idle task boosting is a nono in general. There is one
3352 * exception, when PREEMPT_RT and NOHZ is active:
3354 * The idle task calls get_next_timer_interrupt() and holds
3355 * the timer wheel base->lock on the CPU and another CPU wants
3356 * to access the timer (probably to cancel it). We can safely
3357 * ignore the boosting request, as the idle CPU runs this code
3358 * with interrupts disabled and will complete the lock
3359 * protected section without being interrupted. So there is no
3360 * real need to boost.
3362 if (unlikely(p == rq->idle)) {
3363 WARN_ON(p != rq->curr);
3364 WARN_ON(p->pi_blocked_on);
3368 trace_sched_pi_setprio(p, prio);
3370 prev_class = p->sched_class;
3371 queued = task_on_rq_queued(p);
3372 running = task_current(rq, p);
3374 dequeue_task(rq, p, DEQUEUE_SAVE);
3376 put_prev_task(rq, p);
3379 * Boosting condition are:
3380 * 1. -rt task is running and holds mutex A
3381 * --> -dl task blocks on mutex A
3383 * 2. -dl task is running and holds mutex A
3384 * --> -dl task blocks on mutex A and could preempt the
3387 if (dl_prio(prio)) {
3388 struct task_struct *pi_task = rt_mutex_get_top_task(p);
3389 if (!dl_prio(p->normal_prio) ||
3390 (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
3391 p->dl.dl_boosted = 1;
3392 enqueue_flag |= ENQUEUE_REPLENISH;
3394 p->dl.dl_boosted = 0;
3395 p->sched_class = &dl_sched_class;
3396 } else if (rt_prio(prio)) {
3397 if (dl_prio(oldprio))
3398 p->dl.dl_boosted = 0;
3400 enqueue_flag |= ENQUEUE_HEAD;
3401 p->sched_class = &rt_sched_class;
3403 if (dl_prio(oldprio))
3404 p->dl.dl_boosted = 0;
3405 if (rt_prio(oldprio))
3407 p->sched_class = &fair_sched_class;
3413 p->sched_class->set_curr_task(rq);
3415 enqueue_task(rq, p, enqueue_flag);
3417 check_class_changed(rq, p, prev_class, oldprio);
3419 preempt_disable(); /* avoid rq from going away on us */
3420 __task_rq_unlock(rq);
3422 balance_callback(rq);
3427 void set_user_nice(struct task_struct *p, long nice)
3429 int old_prio, delta, queued;
3430 unsigned long flags;
3433 if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
3436 * We have to be careful, if called from sys_setpriority(),
3437 * the task might be in the middle of scheduling on another CPU.
3439 rq = task_rq_lock(p, &flags);
3441 * The RT priorities are set via sched_setscheduler(), but we still
3442 * allow the 'normal' nice value to be set - but as expected
3443 * it wont have any effect on scheduling until the task is
3444 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3446 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
3447 p->static_prio = NICE_TO_PRIO(nice);
3450 queued = task_on_rq_queued(p);
3452 dequeue_task(rq, p, DEQUEUE_SAVE);
3454 p->static_prio = NICE_TO_PRIO(nice);
3457 p->prio = effective_prio(p);
3458 delta = p->prio - old_prio;
3461 enqueue_task(rq, p, ENQUEUE_RESTORE);
3463 * If the task increased its priority or is running and
3464 * lowered its priority, then reschedule its CPU:
3466 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3470 task_rq_unlock(rq, p, &flags);
3472 EXPORT_SYMBOL(set_user_nice);
3475 * can_nice - check if a task can reduce its nice value
3479 int can_nice(const struct task_struct *p, const int nice)
3481 /* convert nice value [19,-20] to rlimit style value [1,40] */
3482 int nice_rlim = nice_to_rlimit(nice);
3484 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3485 capable(CAP_SYS_NICE));
3488 #ifdef __ARCH_WANT_SYS_NICE
3491 * sys_nice - change the priority of the current process.
3492 * @increment: priority increment
3494 * sys_setpriority is a more generic, but much slower function that
3495 * does similar things.
3497 SYSCALL_DEFINE1(nice, int, increment)
3502 * Setpriority might change our priority at the same moment.
3503 * We don't have to worry. Conceptually one call occurs first
3504 * and we have a single winner.
3506 increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
3507 nice = task_nice(current) + increment;
3509 nice = clamp_val(nice, MIN_NICE, MAX_NICE);
3510 if (increment < 0 && !can_nice(current, nice))
3513 retval = security_task_setnice(current, nice);
3517 set_user_nice(current, nice);
3524 * task_prio - return the priority value of a given task.
3525 * @p: the task in question.
3527 * Return: The priority value as seen by users in /proc.
3528 * RT tasks are offset by -200. Normal tasks are centered
3529 * around 0, value goes from -16 to +15.
3531 int task_prio(const struct task_struct *p)
3533 return p->prio - MAX_RT_PRIO;
3537 * idle_cpu - is a given cpu idle currently?
3538 * @cpu: the processor in question.
3540 * Return: 1 if the CPU is currently idle. 0 otherwise.
3542 int idle_cpu(int cpu)
3544 struct rq *rq = cpu_rq(cpu);
3546 if (rq->curr != rq->idle)
3553 if (!llist_empty(&rq->wake_list))
3561 * idle_task - return the idle task for a given cpu.
3562 * @cpu: the processor in question.
3564 * Return: The idle task for the cpu @cpu.
3566 struct task_struct *idle_task(int cpu)
3568 return cpu_rq(cpu)->idle;
3572 * find_process_by_pid - find a process with a matching PID value.
3573 * @pid: the pid in question.
3575 * The task of @pid, if found. %NULL otherwise.
3577 static struct task_struct *find_process_by_pid(pid_t pid)
3579 return pid ? find_task_by_vpid(pid) : current;
3583 * This function initializes the sched_dl_entity of a newly becoming
3584 * SCHED_DEADLINE task.
3586 * Only the static values are considered here, the actual runtime and the
3587 * absolute deadline will be properly calculated when the task is enqueued
3588 * for the first time with its new policy.
3591 __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
3593 struct sched_dl_entity *dl_se = &p->dl;
3595 dl_se->dl_runtime = attr->sched_runtime;
3596 dl_se->dl_deadline = attr->sched_deadline;
3597 dl_se->dl_period = attr->sched_period ?: dl_se->dl_deadline;
3598 dl_se->flags = attr->sched_flags;
3599 dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
3602 * Changing the parameters of a task is 'tricky' and we're not doing
3603 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3605 * What we SHOULD do is delay the bandwidth release until the 0-lag
3606 * point. This would include retaining the task_struct until that time
3607 * and change dl_overflow() to not immediately decrement the current
3610 * Instead we retain the current runtime/deadline and let the new
3611 * parameters take effect after the current reservation period lapses.
3612 * This is safe (albeit pessimistic) because the 0-lag point is always
3613 * before the current scheduling deadline.
3615 * We can still have temporary overloads because we do not delay the
3616 * change in bandwidth until that time; so admission control is
3617 * not on the safe side. It does however guarantee tasks will never
3618 * consume more than promised.
3623 * sched_setparam() passes in -1 for its policy, to let the functions
3624 * it calls know not to change it.
3626 #define SETPARAM_POLICY -1
3628 static void __setscheduler_params(struct task_struct *p,
3629 const struct sched_attr *attr)
3631 int policy = attr->sched_policy;
3633 if (policy == SETPARAM_POLICY)
3638 if (dl_policy(policy))
3639 __setparam_dl(p, attr);
3640 else if (fair_policy(policy))
3641 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
3644 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3645 * !rt_policy. Always setting this ensures that things like
3646 * getparam()/getattr() don't report silly values for !rt tasks.
3648 p->rt_priority = attr->sched_priority;
3649 p->normal_prio = normal_prio(p);
3653 /* Actually do priority change: must hold pi & rq lock. */
3654 static void __setscheduler(struct rq *rq, struct task_struct *p,
3655 const struct sched_attr *attr, bool keep_boost)
3657 __setscheduler_params(p, attr);
3660 * Keep a potential priority boosting if called from
3661 * sched_setscheduler().
3664 p->prio = rt_mutex_get_effective_prio(p, normal_prio(p));
3666 p->prio = normal_prio(p);
3668 if (dl_prio(p->prio))
3669 p->sched_class = &dl_sched_class;
3670 else if (rt_prio(p->prio))
3671 p->sched_class = &rt_sched_class;
3673 p->sched_class = &fair_sched_class;
3677 __getparam_dl(struct task_struct *p, struct sched_attr *attr)
3679 struct sched_dl_entity *dl_se = &p->dl;
3681 attr->sched_priority = p->rt_priority;
3682 attr->sched_runtime = dl_se->dl_runtime;
3683 attr->sched_deadline = dl_se->dl_deadline;
3684 attr->sched_period = dl_se->dl_period;
3685 attr->sched_flags = dl_se->flags;
3689 * This function validates the new parameters of a -deadline task.
3690 * We ask for the deadline not being zero, and greater or equal
3691 * than the runtime, as well as the period of being zero or
3692 * greater than deadline. Furthermore, we have to be sure that
3693 * user parameters are above the internal resolution of 1us (we
3694 * check sched_runtime only since it is always the smaller one) and
3695 * below 2^63 ns (we have to check both sched_deadline and
3696 * sched_period, as the latter can be zero).
3699 __checkparam_dl(const struct sched_attr *attr)
3702 if (attr->sched_deadline == 0)
3706 * Since we truncate DL_SCALE bits, make sure we're at least
3709 if (attr->sched_runtime < (1ULL << DL_SCALE))
3713 * Since we use the MSB for wrap-around and sign issues, make
3714 * sure it's not set (mind that period can be equal to zero).
3716 if (attr->sched_deadline & (1ULL << 63) ||
3717 attr->sched_period & (1ULL << 63))
3720 /* runtime <= deadline <= period (if period != 0) */
3721 if ((attr->sched_period != 0 &&
3722 attr->sched_period < attr->sched_deadline) ||
3723 attr->sched_deadline < attr->sched_runtime)
3730 * check the target process has a UID that matches the current process's
3732 static bool check_same_owner(struct task_struct *p)
3734 const struct cred *cred = current_cred(), *pcred;
3738 pcred = __task_cred(p);
3739 match = (uid_eq(cred->euid, pcred->euid) ||
3740 uid_eq(cred->euid, pcred->uid));
3745 static bool dl_param_changed(struct task_struct *p,
3746 const struct sched_attr *attr)
3748 struct sched_dl_entity *dl_se = &p->dl;
3750 if (dl_se->dl_runtime != attr->sched_runtime ||
3751 dl_se->dl_deadline != attr->sched_deadline ||
3752 dl_se->dl_period != attr->sched_period ||
3753 dl_se->flags != attr->sched_flags)
3759 static int __sched_setscheduler(struct task_struct *p,
3760 const struct sched_attr *attr,
3763 int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
3764 MAX_RT_PRIO - 1 - attr->sched_priority;
3765 int retval, oldprio, oldpolicy = -1, queued, running;
3766 int new_effective_prio, policy = attr->sched_policy;
3767 unsigned long flags;
3768 const struct sched_class *prev_class;
3772 /* may grab non-irq protected spin_locks */
3773 BUG_ON(in_interrupt());
3775 /* double check policy once rq lock held */
3777 reset_on_fork = p->sched_reset_on_fork;
3778 policy = oldpolicy = p->policy;
3780 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
3782 if (!valid_policy(policy))
3786 if (attr->sched_flags & ~(SCHED_FLAG_RESET_ON_FORK))
3790 * Valid priorities for SCHED_FIFO and SCHED_RR are
3791 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3792 * SCHED_BATCH and SCHED_IDLE is 0.
3794 if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
3795 (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
3797 if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
3798 (rt_policy(policy) != (attr->sched_priority != 0)))
3802 * Allow unprivileged RT tasks to decrease priority:
3804 if (user && !capable(CAP_SYS_NICE)) {
3805 if (fair_policy(policy)) {
3806 if (attr->sched_nice < task_nice(p) &&
3807 !can_nice(p, attr->sched_nice))
3811 if (rt_policy(policy)) {
3812 unsigned long rlim_rtprio =
3813 task_rlimit(p, RLIMIT_RTPRIO);
3815 /* can't set/change the rt policy */
3816 if (policy != p->policy && !rlim_rtprio)
3819 /* can't increase priority */
3820 if (attr->sched_priority > p->rt_priority &&
3821 attr->sched_priority > rlim_rtprio)
3826 * Can't set/change SCHED_DEADLINE policy at all for now
3827 * (safest behavior); in the future we would like to allow
3828 * unprivileged DL tasks to increase their relative deadline
3829 * or reduce their runtime (both ways reducing utilization)
3831 if (dl_policy(policy))
3835 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3836 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3838 if (idle_policy(p->policy) && !idle_policy(policy)) {
3839 if (!can_nice(p, task_nice(p)))
3843 /* can't change other user's priorities */
3844 if (!check_same_owner(p))
3847 /* Normal users shall not reset the sched_reset_on_fork flag */
3848 if (p->sched_reset_on_fork && !reset_on_fork)
3853 retval = security_task_setscheduler(p);
3859 * make sure no PI-waiters arrive (or leave) while we are
3860 * changing the priority of the task:
3862 * To be able to change p->policy safely, the appropriate
3863 * runqueue lock must be held.
3865 rq = task_rq_lock(p, &flags);
3868 * Changing the policy of the stop threads its a very bad idea
3870 if (p == rq->stop) {
3871 task_rq_unlock(rq, p, &flags);
3876 * If not changing anything there's no need to proceed further,
3877 * but store a possible modification of reset_on_fork.
3879 if (unlikely(policy == p->policy)) {
3880 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
3882 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
3884 if (dl_policy(policy) && dl_param_changed(p, attr))
3887 p->sched_reset_on_fork = reset_on_fork;
3888 task_rq_unlock(rq, p, &flags);
3894 #ifdef CONFIG_RT_GROUP_SCHED
3896 * Do not allow realtime tasks into groups that have no runtime
3899 if (rt_bandwidth_enabled() && rt_policy(policy) &&
3900 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3901 !task_group_is_autogroup(task_group(p))) {
3902 task_rq_unlock(rq, p, &flags);
3907 if (dl_bandwidth_enabled() && dl_policy(policy)) {
3908 cpumask_t *span = rq->rd->span;
3911 * Don't allow tasks with an affinity mask smaller than
3912 * the entire root_domain to become SCHED_DEADLINE. We
3913 * will also fail if there's no bandwidth available.
3915 if (!cpumask_subset(span, &p->cpus_allowed) ||
3916 rq->rd->dl_bw.bw == 0) {
3917 task_rq_unlock(rq, p, &flags);
3924 /* recheck policy now with rq lock held */
3925 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3926 policy = oldpolicy = -1;
3927 task_rq_unlock(rq, p, &flags);
3932 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3933 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3936 if ((dl_policy(policy) || dl_task(p)) && dl_overflow(p, policy, attr)) {
3937 task_rq_unlock(rq, p, &flags);
3941 p->sched_reset_on_fork = reset_on_fork;
3946 * Take priority boosted tasks into account. If the new
3947 * effective priority is unchanged, we just store the new
3948 * normal parameters and do not touch the scheduler class and
3949 * the runqueue. This will be done when the task deboost
3952 new_effective_prio = rt_mutex_get_effective_prio(p, newprio);
3953 if (new_effective_prio == oldprio) {
3954 __setscheduler_params(p, attr);
3955 task_rq_unlock(rq, p, &flags);
3960 queued = task_on_rq_queued(p);
3961 running = task_current(rq, p);
3963 dequeue_task(rq, p, DEQUEUE_SAVE);
3965 put_prev_task(rq, p);
3967 prev_class = p->sched_class;
3968 __setscheduler(rq, p, attr, pi);
3971 p->sched_class->set_curr_task(rq);
3973 int enqueue_flags = ENQUEUE_RESTORE;
3975 * We enqueue to tail when the priority of a task is
3976 * increased (user space view).
3978 if (oldprio <= p->prio)
3979 enqueue_flags |= ENQUEUE_HEAD;
3981 enqueue_task(rq, p, enqueue_flags);
3984 check_class_changed(rq, p, prev_class, oldprio);
3985 preempt_disable(); /* avoid rq from going away on us */
3986 task_rq_unlock(rq, p, &flags);
3989 rt_mutex_adjust_pi(p);
3992 * Run balance callbacks after we've adjusted the PI chain.
3994 balance_callback(rq);
4000 static int _sched_setscheduler(struct task_struct *p, int policy,
4001 const struct sched_param *param, bool check)
4003 struct sched_attr attr = {
4004 .sched_policy = policy,
4005 .sched_priority = param->sched_priority,
4006 .sched_nice = PRIO_TO_NICE(p->static_prio),
4009 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4010 if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
4011 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4012 policy &= ~SCHED_RESET_ON_FORK;
4013 attr.sched_policy = policy;
4016 return __sched_setscheduler(p, &attr, check, true);
4019 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4020 * @p: the task in question.
4021 * @policy: new policy.
4022 * @param: structure containing the new RT priority.
4024 * Return: 0 on success. An error code otherwise.
4026 * NOTE that the task may be already dead.
4028 int sched_setscheduler(struct task_struct *p, int policy,
4029 const struct sched_param *param)
4031 return _sched_setscheduler(p, policy, param, true);
4033 EXPORT_SYMBOL_GPL(sched_setscheduler);
4035 int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
4037 return __sched_setscheduler(p, attr, true, true);
4039 EXPORT_SYMBOL_GPL(sched_setattr);
4042 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4043 * @p: the task in question.
4044 * @policy: new policy.
4045 * @param: structure containing the new RT priority.
4047 * Just like sched_setscheduler, only don't bother checking if the
4048 * current context has permission. For example, this is needed in
4049 * stop_machine(): we create temporary high priority worker threads,
4050 * but our caller might not have that capability.
4052 * Return: 0 on success. An error code otherwise.
4054 int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4055 const struct sched_param *param)
4057 return _sched_setscheduler(p, policy, param, false);
4059 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
4062 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4064 struct sched_param lparam;
4065 struct task_struct *p;
4068 if (!param || pid < 0)
4070 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4075 p = find_process_by_pid(pid);
4077 retval = sched_setscheduler(p, policy, &lparam);
4084 * Mimics kernel/events/core.c perf_copy_attr().
4086 static int sched_copy_attr(struct sched_attr __user *uattr,
4087 struct sched_attr *attr)
4092 if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
4096 * zero the full structure, so that a short copy will be nice.
4098 memset(attr, 0, sizeof(*attr));
4100 ret = get_user(size, &uattr->size);
4104 if (size > PAGE_SIZE) /* silly large */
4107 if (!size) /* abi compat */
4108 size = SCHED_ATTR_SIZE_VER0;
4110 if (size < SCHED_ATTR_SIZE_VER0)
4114 * If we're handed a bigger struct than we know of,
4115 * ensure all the unknown bits are 0 - i.e. new
4116 * user-space does not rely on any kernel feature
4117 * extensions we dont know about yet.
4119 if (size > sizeof(*attr)) {
4120 unsigned char __user *addr;
4121 unsigned char __user *end;
4124 addr = (void __user *)uattr + sizeof(*attr);
4125 end = (void __user *)uattr + size;
4127 for (; addr < end; addr++) {
4128 ret = get_user(val, addr);
4134 size = sizeof(*attr);
4137 ret = copy_from_user(attr, uattr, size);
4142 * XXX: do we want to be lenient like existing syscalls; or do we want
4143 * to be strict and return an error on out-of-bounds values?
4145 attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
4150 put_user(sizeof(*attr), &uattr->size);
4155 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4156 * @pid: the pid in question.
4157 * @policy: new policy.
4158 * @param: structure containing the new RT priority.
4160 * Return: 0 on success. An error code otherwise.
4162 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4163 struct sched_param __user *, param)
4165 /* negative values for policy are not valid */
4169 return do_sched_setscheduler(pid, policy, param);
4173 * sys_sched_setparam - set/change the RT priority of a thread
4174 * @pid: the pid in question.
4175 * @param: structure containing the new RT priority.
4177 * Return: 0 on success. An error code otherwise.
4179 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4181 return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
4185 * sys_sched_setattr - same as above, but with extended sched_attr
4186 * @pid: the pid in question.
4187 * @uattr: structure containing the extended parameters.
4188 * @flags: for future extension.
4190 SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
4191 unsigned int, flags)
4193 struct sched_attr attr;
4194 struct task_struct *p;
4197 if (!uattr || pid < 0 || flags)
4200 retval = sched_copy_attr(uattr, &attr);
4204 if ((int)attr.sched_policy < 0)
4209 p = find_process_by_pid(pid);
4211 retval = sched_setattr(p, &attr);
4218 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4219 * @pid: the pid in question.
4221 * Return: On success, the policy of the thread. Otherwise, a negative error
4224 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4226 struct task_struct *p;
4234 p = find_process_by_pid(pid);
4236 retval = security_task_getscheduler(p);
4239 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4246 * sys_sched_getparam - get the RT priority of a thread
4247 * @pid: the pid in question.
4248 * @param: structure containing the RT priority.
4250 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4253 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4255 struct sched_param lp = { .sched_priority = 0 };
4256 struct task_struct *p;
4259 if (!param || pid < 0)
4263 p = find_process_by_pid(pid);
4268 retval = security_task_getscheduler(p);
4272 if (task_has_rt_policy(p))
4273 lp.sched_priority = p->rt_priority;
4277 * This one might sleep, we cannot do it with a spinlock held ...
4279 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4288 static int sched_read_attr(struct sched_attr __user *uattr,
4289 struct sched_attr *attr,
4294 if (!access_ok(VERIFY_WRITE, uattr, usize))
4298 * If we're handed a smaller struct than we know of,
4299 * ensure all the unknown bits are 0 - i.e. old
4300 * user-space does not get uncomplete information.
4302 if (usize < sizeof(*attr)) {
4303 unsigned char *addr;
4306 addr = (void *)attr + usize;
4307 end = (void *)attr + sizeof(*attr);
4309 for (; addr < end; addr++) {
4317 ret = copy_to_user(uattr, attr, attr->size);
4325 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4326 * @pid: the pid in question.
4327 * @uattr: structure containing the extended parameters.
4328 * @size: sizeof(attr) for fwd/bwd comp.
4329 * @flags: for future extension.
4331 SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
4332 unsigned int, size, unsigned int, flags)
4334 struct sched_attr attr = {
4335 .size = sizeof(struct sched_attr),
4337 struct task_struct *p;
4340 if (!uattr || pid < 0 || size > PAGE_SIZE ||
4341 size < SCHED_ATTR_SIZE_VER0 || flags)
4345 p = find_process_by_pid(pid);
4350 retval = security_task_getscheduler(p);
4354 attr.sched_policy = p->policy;
4355 if (p->sched_reset_on_fork)
4356 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
4357 if (task_has_dl_policy(p))
4358 __getparam_dl(p, &attr);
4359 else if (task_has_rt_policy(p))
4360 attr.sched_priority = p->rt_priority;
4362 attr.sched_nice = task_nice(p);
4366 retval = sched_read_attr(uattr, &attr, size);
4374 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4376 cpumask_var_t cpus_allowed, new_mask;
4377 struct task_struct *p;
4382 p = find_process_by_pid(pid);
4388 /* Prevent p going away */
4392 if (p->flags & PF_NO_SETAFFINITY) {
4396 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4400 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4402 goto out_free_cpus_allowed;
4405 if (!check_same_owner(p)) {
4407 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
4409 goto out_free_new_mask;
4414 retval = security_task_setscheduler(p);
4416 goto out_free_new_mask;
4419 cpuset_cpus_allowed(p, cpus_allowed);
4420 cpumask_and(new_mask, in_mask, cpus_allowed);
4423 * Since bandwidth control happens on root_domain basis,
4424 * if admission test is enabled, we only admit -deadline
4425 * tasks allowed to run on all the CPUs in the task's
4429 if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
4431 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
4434 goto out_free_new_mask;
4440 retval = __set_cpus_allowed_ptr(p, new_mask, true);
4443 cpuset_cpus_allowed(p, cpus_allowed);
4444 if (!cpumask_subset(new_mask, cpus_allowed)) {
4446 * We must have raced with a concurrent cpuset
4447 * update. Just reset the cpus_allowed to the
4448 * cpuset's cpus_allowed
4450 cpumask_copy(new_mask, cpus_allowed);
4455 free_cpumask_var(new_mask);
4456 out_free_cpus_allowed:
4457 free_cpumask_var(cpus_allowed);
4463 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4464 struct cpumask *new_mask)
4466 if (len < cpumask_size())
4467 cpumask_clear(new_mask);
4468 else if (len > cpumask_size())
4469 len = cpumask_size();
4471 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4475 * sys_sched_setaffinity - set the cpu affinity of a process
4476 * @pid: pid of the process
4477 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4478 * @user_mask_ptr: user-space pointer to the new cpu mask
4480 * Return: 0 on success. An error code otherwise.
4482 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4483 unsigned long __user *, user_mask_ptr)
4485 cpumask_var_t new_mask;
4488 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4491 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4493 retval = sched_setaffinity(pid, new_mask);
4494 free_cpumask_var(new_mask);
4498 long sched_getaffinity(pid_t pid, struct cpumask *mask)
4500 struct task_struct *p;
4501 unsigned long flags;
4507 p = find_process_by_pid(pid);
4511 retval = security_task_getscheduler(p);
4515 raw_spin_lock_irqsave(&p->pi_lock, flags);
4516 cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
4517 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4526 * sys_sched_getaffinity - get the cpu affinity of a process
4527 * @pid: pid of the process
4528 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4529 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4531 * Return: 0 on success. An error code otherwise.
4533 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4534 unsigned long __user *, user_mask_ptr)
4539 if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4541 if (len & (sizeof(unsigned long)-1))
4544 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4547 ret = sched_getaffinity(pid, mask);
4549 size_t retlen = min_t(size_t, len, cpumask_size());
4551 if (copy_to_user(user_mask_ptr, mask, retlen))
4556 free_cpumask_var(mask);
4562 * sys_sched_yield - yield the current processor to other threads.
4564 * This function yields the current CPU to other tasks. If there are no
4565 * other threads running on this CPU then this function will return.
4569 SYSCALL_DEFINE0(sched_yield)
4571 struct rq *rq = this_rq_lock();
4573 schedstat_inc(rq, yld_count);
4574 current->sched_class->yield_task(rq);
4577 * Since we are going to call schedule() anyway, there's
4578 * no need to preempt or enable interrupts:
4580 __release(rq->lock);
4581 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4582 do_raw_spin_unlock(&rq->lock);
4583 sched_preempt_enable_no_resched();
4590 int __sched _cond_resched(void)
4592 if (should_resched(0)) {
4593 preempt_schedule_common();
4598 EXPORT_SYMBOL(_cond_resched);
4601 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4602 * call schedule, and on return reacquire the lock.
4604 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4605 * operations here to prevent schedule() from being called twice (once via
4606 * spin_unlock(), once by hand).
4608 int __cond_resched_lock(spinlock_t *lock)
4610 int resched = should_resched(PREEMPT_LOCK_OFFSET);
4613 lockdep_assert_held(lock);
4615 if (spin_needbreak(lock) || resched) {
4618 preempt_schedule_common();
4626 EXPORT_SYMBOL(__cond_resched_lock);
4628 int __sched __cond_resched_softirq(void)
4630 BUG_ON(!in_softirq());
4632 if (should_resched(SOFTIRQ_DISABLE_OFFSET)) {
4634 preempt_schedule_common();
4640 EXPORT_SYMBOL(__cond_resched_softirq);
4643 * yield - yield the current processor to other threads.
4645 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4647 * The scheduler is at all times free to pick the calling task as the most
4648 * eligible task to run, if removing the yield() call from your code breaks
4649 * it, its already broken.
4651 * Typical broken usage is:
4656 * where one assumes that yield() will let 'the other' process run that will
4657 * make event true. If the current task is a SCHED_FIFO task that will never
4658 * happen. Never use yield() as a progress guarantee!!
4660 * If you want to use yield() to wait for something, use wait_event().
4661 * If you want to use yield() to be 'nice' for others, use cond_resched().
4662 * If you still want to use yield(), do not!
4664 void __sched yield(void)
4666 set_current_state(TASK_RUNNING);
4669 EXPORT_SYMBOL(yield);
4672 * yield_to - yield the current processor to another thread in
4673 * your thread group, or accelerate that thread toward the
4674 * processor it's on.
4676 * @preempt: whether task preemption is allowed or not
4678 * It's the caller's job to ensure that the target task struct
4679 * can't go away on us before we can do any checks.
4682 * true (>0) if we indeed boosted the target task.
4683 * false (0) if we failed to boost the target.
4684 * -ESRCH if there's no task to yield to.
4686 int __sched yield_to(struct task_struct *p, bool preempt)
4688 struct task_struct *curr = current;
4689 struct rq *rq, *p_rq;
4690 unsigned long flags;
4693 local_irq_save(flags);
4699 * If we're the only runnable task on the rq and target rq also
4700 * has only one task, there's absolutely no point in yielding.
4702 if (rq->nr_running == 1 && p_rq->nr_running == 1) {
4707 double_rq_lock(rq, p_rq);
4708 if (task_rq(p) != p_rq) {
4709 double_rq_unlock(rq, p_rq);
4713 if (!curr->sched_class->yield_to_task)
4716 if (curr->sched_class != p->sched_class)
4719 if (task_running(p_rq, p) || p->state)
4722 yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4724 schedstat_inc(rq, yld_count);
4726 * Make p's CPU reschedule; pick_next_entity takes care of
4729 if (preempt && rq != p_rq)
4734 double_rq_unlock(rq, p_rq);
4736 local_irq_restore(flags);
4743 EXPORT_SYMBOL_GPL(yield_to);
4746 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4747 * that process accounting knows that this is a task in IO wait state.
4749 long __sched io_schedule_timeout(long timeout)
4751 int old_iowait = current->in_iowait;
4755 current->in_iowait = 1;
4756 blk_schedule_flush_plug(current);
4758 delayacct_blkio_start();
4760 atomic_inc(&rq->nr_iowait);
4761 ret = schedule_timeout(timeout);
4762 current->in_iowait = old_iowait;
4763 atomic_dec(&rq->nr_iowait);
4764 delayacct_blkio_end();
4768 EXPORT_SYMBOL(io_schedule_timeout);
4771 * sys_sched_get_priority_max - return maximum RT priority.
4772 * @policy: scheduling class.
4774 * Return: On success, this syscall returns the maximum
4775 * rt_priority that can be used by a given scheduling class.
4776 * On failure, a negative error code is returned.
4778 SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4785 ret = MAX_USER_RT_PRIO-1;
4787 case SCHED_DEADLINE:
4798 * sys_sched_get_priority_min - return minimum RT priority.
4799 * @policy: scheduling class.
4801 * Return: On success, this syscall returns the minimum
4802 * rt_priority that can be used by a given scheduling class.
4803 * On failure, a negative error code is returned.
4805 SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4814 case SCHED_DEADLINE:
4824 * sys_sched_rr_get_interval - return the default timeslice of a process.
4825 * @pid: pid of the process.
4826 * @interval: userspace pointer to the timeslice value.
4828 * this syscall writes the default timeslice value of a given process
4829 * into the user-space timespec buffer. A value of '0' means infinity.
4831 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4834 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4835 struct timespec __user *, interval)
4837 struct task_struct *p;
4838 unsigned int time_slice;
4839 unsigned long flags;
4849 p = find_process_by_pid(pid);
4853 retval = security_task_getscheduler(p);
4857 rq = task_rq_lock(p, &flags);
4859 if (p->sched_class->get_rr_interval)
4860 time_slice = p->sched_class->get_rr_interval(rq, p);
4861 task_rq_unlock(rq, p, &flags);
4864 jiffies_to_timespec(time_slice, &t);
4865 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4873 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4875 void sched_show_task(struct task_struct *p)
4877 unsigned long free = 0;
4879 unsigned long state = p->state;
4882 state = __ffs(state) + 1;
4883 printk(KERN_INFO "%-15.15s %c", p->comm,
4884 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4885 #if BITS_PER_LONG == 32
4886 if (state == TASK_RUNNING)
4887 printk(KERN_CONT " running ");
4889 printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4891 if (state == TASK_RUNNING)
4892 printk(KERN_CONT " running task ");
4894 printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4896 #ifdef CONFIG_DEBUG_STACK_USAGE
4897 free = stack_not_used(p);
4902 ppid = task_pid_nr(rcu_dereference(p->real_parent));
4904 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4905 task_pid_nr(p), ppid,
4906 (unsigned long)task_thread_info(p)->flags);
4908 print_worker_info(KERN_INFO, p);
4909 show_stack(p, NULL);
4912 void show_state_filter(unsigned long state_filter)
4914 struct task_struct *g, *p;
4916 #if BITS_PER_LONG == 32
4918 " task PC stack pid father\n");
4921 " task PC stack pid father\n");
4924 for_each_process_thread(g, p) {
4926 * reset the NMI-timeout, listing all files on a slow
4927 * console might take a lot of time:
4929 touch_nmi_watchdog();
4930 if (!state_filter || (p->state & state_filter))
4934 touch_all_softlockup_watchdogs();
4936 #ifdef CONFIG_SCHED_DEBUG
4937 sysrq_sched_debug_show();
4941 * Only show locks if all tasks are dumped:
4944 debug_show_all_locks();
4947 void init_idle_bootup_task(struct task_struct *idle)
4949 idle->sched_class = &idle_sched_class;
4953 * init_idle - set up an idle thread for a given CPU
4954 * @idle: task in question
4955 * @cpu: cpu the idle task belongs to
4957 * NOTE: this function does not set the idle thread's NEED_RESCHED
4958 * flag, to make booting more robust.
4960 void init_idle(struct task_struct *idle, int cpu)
4962 struct rq *rq = cpu_rq(cpu);
4963 unsigned long flags;
4965 raw_spin_lock_irqsave(&idle->pi_lock, flags);
4966 raw_spin_lock(&rq->lock);
4968 __sched_fork(0, idle);
4969 idle->state = TASK_RUNNING;
4970 idle->se.exec_start = sched_clock();
4974 * Its possible that init_idle() gets called multiple times on a task,
4975 * in that case do_set_cpus_allowed() will not do the right thing.
4977 * And since this is boot we can forgo the serialization.
4979 set_cpus_allowed_common(idle, cpumask_of(cpu));
4982 * We're having a chicken and egg problem, even though we are
4983 * holding rq->lock, the cpu isn't yet set to this cpu so the
4984 * lockdep check in task_group() will fail.
4986 * Similar case to sched_fork(). / Alternatively we could
4987 * use task_rq_lock() here and obtain the other rq->lock.
4992 __set_task_cpu(idle, cpu);
4995 rq->curr = rq->idle = idle;
4996 idle->on_rq = TASK_ON_RQ_QUEUED;
5000 raw_spin_unlock(&rq->lock);
5001 raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
5003 /* Set the preempt count _outside_ the spinlocks! */
5004 init_idle_preempt_count(idle, cpu);
5007 * The idle tasks have their own, simple scheduling class:
5009 idle->sched_class = &idle_sched_class;
5010 ftrace_graph_init_idle_task(idle, cpu);
5011 vtime_init_idle(idle, cpu);
5013 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
5017 int cpuset_cpumask_can_shrink(const struct cpumask *cur,
5018 const struct cpumask *trial)
5020 int ret = 1, trial_cpus;
5021 struct dl_bw *cur_dl_b;
5022 unsigned long flags;
5024 if (!cpumask_weight(cur))
5027 rcu_read_lock_sched();
5028 cur_dl_b = dl_bw_of(cpumask_any(cur));
5029 trial_cpus = cpumask_weight(trial);
5031 raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
5032 if (cur_dl_b->bw != -1 &&
5033 cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
5035 raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
5036 rcu_read_unlock_sched();
5041 int task_can_attach(struct task_struct *p,
5042 const struct cpumask *cs_cpus_allowed)
5047 * Kthreads which disallow setaffinity shouldn't be moved
5048 * to a new cpuset; we don't want to change their cpu
5049 * affinity and isolating such threads by their set of
5050 * allowed nodes is unnecessary. Thus, cpusets are not
5051 * applicable for such threads. This prevents checking for
5052 * success of set_cpus_allowed_ptr() on all attached tasks
5053 * before cpus_allowed may be changed.
5055 if (p->flags & PF_NO_SETAFFINITY) {
5061 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
5063 unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
5068 unsigned long flags;
5070 rcu_read_lock_sched();
5071 dl_b = dl_bw_of(dest_cpu);
5072 raw_spin_lock_irqsave(&dl_b->lock, flags);
5073 cpus = dl_bw_cpus(dest_cpu);
5074 overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
5079 * We reserve space for this task in the destination
5080 * root_domain, as we can't fail after this point.
5081 * We will free resources in the source root_domain
5082 * later on (see set_cpus_allowed_dl()).
5084 __dl_add(dl_b, p->dl.dl_bw);
5086 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
5087 rcu_read_unlock_sched();
5097 #ifdef CONFIG_NUMA_BALANCING
5098 /* Migrate current task p to target_cpu */
5099 int migrate_task_to(struct task_struct *p, int target_cpu)
5101 struct migration_arg arg = { p, target_cpu };
5102 int curr_cpu = task_cpu(p);
5104 if (curr_cpu == target_cpu)
5107 if (!cpumask_test_cpu(target_cpu, tsk_cpus_allowed(p)))
5110 /* TODO: This is not properly updating schedstats */
5112 trace_sched_move_numa(p, curr_cpu, target_cpu);
5113 return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
5117 * Requeue a task on a given node and accurately track the number of NUMA
5118 * tasks on the runqueues
5120 void sched_setnuma(struct task_struct *p, int nid)
5123 unsigned long flags;
5124 bool queued, running;
5126 rq = task_rq_lock(p, &flags);
5127 queued = task_on_rq_queued(p);
5128 running = task_current(rq, p);
5131 dequeue_task(rq, p, DEQUEUE_SAVE);
5133 put_prev_task(rq, p);
5135 p->numa_preferred_nid = nid;
5138 p->sched_class->set_curr_task(rq);
5140 enqueue_task(rq, p, ENQUEUE_RESTORE);
5141 task_rq_unlock(rq, p, &flags);
5143 #endif /* CONFIG_NUMA_BALANCING */
5145 #ifdef CONFIG_HOTPLUG_CPU
5147 * Ensures that the idle task is using init_mm right before its cpu goes
5150 void idle_task_exit(void)
5152 struct mm_struct *mm = current->active_mm;
5154 BUG_ON(cpu_online(smp_processor_id()));
5156 if (mm != &init_mm) {
5157 switch_mm(mm, &init_mm, current);
5158 finish_arch_post_lock_switch();
5164 * Since this CPU is going 'away' for a while, fold any nr_active delta
5165 * we might have. Assumes we're called after migrate_tasks() so that the
5166 * nr_active count is stable.
5168 * Also see the comment "Global load-average calculations".
5170 static void calc_load_migrate(struct rq *rq)
5172 long delta = calc_load_fold_active(rq);
5174 atomic_long_add(delta, &calc_load_tasks);
5177 static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
5181 static const struct sched_class fake_sched_class = {
5182 .put_prev_task = put_prev_task_fake,
5185 static struct task_struct fake_task = {
5187 * Avoid pull_{rt,dl}_task()
5189 .prio = MAX_PRIO + 1,
5190 .sched_class = &fake_sched_class,
5194 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5195 * try_to_wake_up()->select_task_rq().
5197 * Called with rq->lock held even though we'er in stop_machine() and
5198 * there's no concurrency possible, we hold the required locks anyway
5199 * because of lock validation efforts.
5201 static void migrate_tasks(struct rq *dead_rq)
5203 struct rq *rq = dead_rq;
5204 struct task_struct *next, *stop = rq->stop;
5208 * Fudge the rq selection such that the below task selection loop
5209 * doesn't get stuck on the currently eligible stop task.
5211 * We're currently inside stop_machine() and the rq is either stuck
5212 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5213 * either way we should never end up calling schedule() until we're
5219 * put_prev_task() and pick_next_task() sched
5220 * class method both need to have an up-to-date
5221 * value of rq->clock[_task]
5223 update_rq_clock(rq);
5227 * There's this thread running, bail when that's the only
5230 if (rq->nr_running == 1)
5234 * pick_next_task assumes pinned rq->lock.
5236 lockdep_pin_lock(&rq->lock);
5237 next = pick_next_task(rq, &fake_task);
5239 next->sched_class->put_prev_task(rq, next);
5242 * Rules for changing task_struct::cpus_allowed are holding
5243 * both pi_lock and rq->lock, such that holding either
5244 * stabilizes the mask.
5246 * Drop rq->lock is not quite as disastrous as it usually is
5247 * because !cpu_active at this point, which means load-balance
5248 * will not interfere. Also, stop-machine.
5250 lockdep_unpin_lock(&rq->lock);
5251 raw_spin_unlock(&rq->lock);
5252 raw_spin_lock(&next->pi_lock);
5253 raw_spin_lock(&rq->lock);
5256 * Since we're inside stop-machine, _nothing_ should have
5257 * changed the task, WARN if weird stuff happened, because in
5258 * that case the above rq->lock drop is a fail too.
5260 if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
5261 raw_spin_unlock(&next->pi_lock);
5265 /* Find suitable destination for @next, with force if needed. */
5266 dest_cpu = select_fallback_rq(dead_rq->cpu, next);
5268 rq = __migrate_task(rq, next, dest_cpu);
5269 if (rq != dead_rq) {
5270 raw_spin_unlock(&rq->lock);
5272 raw_spin_lock(&rq->lock);
5274 raw_spin_unlock(&next->pi_lock);
5279 #endif /* CONFIG_HOTPLUG_CPU */
5281 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5283 static struct ctl_table sd_ctl_dir[] = {
5285 .procname = "sched_domain",
5291 static struct ctl_table sd_ctl_root[] = {
5293 .procname = "kernel",
5295 .child = sd_ctl_dir,
5300 static struct ctl_table *sd_alloc_ctl_entry(int n)
5302 struct ctl_table *entry =
5303 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
5308 static void sd_free_ctl_entry(struct ctl_table **tablep)
5310 struct ctl_table *entry;
5313 * In the intermediate directories, both the child directory and
5314 * procname are dynamically allocated and could fail but the mode
5315 * will always be set. In the lowest directory the names are
5316 * static strings and all have proc handlers.
5318 for (entry = *tablep; entry->mode; entry++) {
5320 sd_free_ctl_entry(&entry->child);
5321 if (entry->proc_handler == NULL)
5322 kfree(entry->procname);
5329 static int min_load_idx = 0;
5330 static int max_load_idx = CPU_LOAD_IDX_MAX-1;
5333 set_table_entry(struct ctl_table *entry,
5334 const char *procname, void *data, int maxlen,
5335 umode_t mode, proc_handler *proc_handler,
5338 entry->procname = procname;
5340 entry->maxlen = maxlen;
5342 entry->proc_handler = proc_handler;
5345 entry->extra1 = &min_load_idx;
5346 entry->extra2 = &max_load_idx;
5350 static struct ctl_table *
5351 sd_alloc_ctl_domain_table(struct sched_domain *sd)
5353 struct ctl_table *table = sd_alloc_ctl_entry(14);
5358 set_table_entry(&table[0], "min_interval", &sd->min_interval,
5359 sizeof(long), 0644, proc_doulongvec_minmax, false);
5360 set_table_entry(&table[1], "max_interval", &sd->max_interval,
5361 sizeof(long), 0644, proc_doulongvec_minmax, false);
5362 set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
5363 sizeof(int), 0644, proc_dointvec_minmax, true);
5364 set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
5365 sizeof(int), 0644, proc_dointvec_minmax, true);
5366 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
5367 sizeof(int), 0644, proc_dointvec_minmax, true);
5368 set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
5369 sizeof(int), 0644, proc_dointvec_minmax, true);
5370 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
5371 sizeof(int), 0644, proc_dointvec_minmax, true);
5372 set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
5373 sizeof(int), 0644, proc_dointvec_minmax, false);
5374 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
5375 sizeof(int), 0644, proc_dointvec_minmax, false);
5376 set_table_entry(&table[9], "cache_nice_tries",
5377 &sd->cache_nice_tries,
5378 sizeof(int), 0644, proc_dointvec_minmax, false);
5379 set_table_entry(&table[10], "flags", &sd->flags,
5380 sizeof(int), 0644, proc_dointvec_minmax, false);
5381 set_table_entry(&table[11], "max_newidle_lb_cost",
5382 &sd->max_newidle_lb_cost,
5383 sizeof(long), 0644, proc_doulongvec_minmax, false);
5384 set_table_entry(&table[12], "name", sd->name,
5385 CORENAME_MAX_SIZE, 0444, proc_dostring, false);
5386 /* &table[13] is terminator */
5391 static struct ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5393 struct ctl_table *entry, *table;
5394 struct sched_domain *sd;
5395 int domain_num = 0, i;
5398 for_each_domain(cpu, sd)
5400 entry = table = sd_alloc_ctl_entry(domain_num + 1);
5405 for_each_domain(cpu, sd) {
5406 snprintf(buf, 32, "domain%d", i);
5407 entry->procname = kstrdup(buf, GFP_KERNEL);
5409 entry->child = sd_alloc_ctl_domain_table(sd);
5416 static struct ctl_table_header *sd_sysctl_header;
5417 static void register_sched_domain_sysctl(void)
5419 int i, cpu_num = num_possible_cpus();
5420 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5423 WARN_ON(sd_ctl_dir[0].child);
5424 sd_ctl_dir[0].child = entry;
5429 for_each_possible_cpu(i) {
5430 snprintf(buf, 32, "cpu%d", i);
5431 entry->procname = kstrdup(buf, GFP_KERNEL);
5433 entry->child = sd_alloc_ctl_cpu_table(i);
5437 WARN_ON(sd_sysctl_header);
5438 sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5441 /* may be called multiple times per register */
5442 static void unregister_sched_domain_sysctl(void)
5444 unregister_sysctl_table(sd_sysctl_header);
5445 sd_sysctl_header = NULL;
5446 if (sd_ctl_dir[0].child)
5447 sd_free_ctl_entry(&sd_ctl_dir[0].child);
5450 static void register_sched_domain_sysctl(void)
5453 static void unregister_sched_domain_sysctl(void)
5456 #endif /* CONFIG_SCHED_DEBUG && CONFIG_SYSCTL */
5458 static void set_rq_online(struct rq *rq)
5461 const struct sched_class *class;
5463 cpumask_set_cpu(rq->cpu, rq->rd->online);
5466 for_each_class(class) {
5467 if (class->rq_online)
5468 class->rq_online(rq);
5473 static void set_rq_offline(struct rq *rq)
5476 const struct sched_class *class;
5478 for_each_class(class) {
5479 if (class->rq_offline)
5480 class->rq_offline(rq);
5483 cpumask_clear_cpu(rq->cpu, rq->rd->online);
5489 * migration_call - callback that gets triggered when a CPU is added.
5490 * Here we can start up the necessary migration thread for the new CPU.
5493 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5495 int cpu = (long)hcpu;
5496 unsigned long flags;
5497 struct rq *rq = cpu_rq(cpu);
5499 switch (action & ~CPU_TASKS_FROZEN) {
5501 case CPU_UP_PREPARE:
5502 rq->calc_load_update = calc_load_update;
5506 /* Update our root-domain */
5507 raw_spin_lock_irqsave(&rq->lock, flags);
5509 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5513 raw_spin_unlock_irqrestore(&rq->lock, flags);
5516 #ifdef CONFIG_HOTPLUG_CPU
5518 sched_ttwu_pending();
5519 /* Update our root-domain */
5520 raw_spin_lock_irqsave(&rq->lock, flags);
5522 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5526 BUG_ON(rq->nr_running != 1); /* the migration thread */
5527 raw_spin_unlock_irqrestore(&rq->lock, flags);
5531 calc_load_migrate(rq);
5536 update_max_interval();
5542 * Register at high priority so that task migration (migrate_all_tasks)
5543 * happens before everything else. This has to be lower priority than
5544 * the notifier in the perf_event subsystem, though.
5546 static struct notifier_block migration_notifier = {
5547 .notifier_call = migration_call,
5548 .priority = CPU_PRI_MIGRATION,
5551 static void set_cpu_rq_start_time(void)
5553 int cpu = smp_processor_id();
5554 struct rq *rq = cpu_rq(cpu);
5555 rq->age_stamp = sched_clock_cpu(cpu);
5558 static int sched_cpu_active(struct notifier_block *nfb,
5559 unsigned long action, void *hcpu)
5561 int cpu = (long)hcpu;
5563 switch (action & ~CPU_TASKS_FROZEN) {
5565 set_cpu_rq_start_time();
5570 * At this point a starting CPU has marked itself as online via
5571 * set_cpu_online(). But it might not yet have marked itself
5572 * as active, which is essential from here on.
5574 set_cpu_active(cpu, true);
5575 stop_machine_unpark(cpu);
5578 case CPU_DOWN_FAILED:
5579 set_cpu_active(cpu, true);
5587 static int sched_cpu_inactive(struct notifier_block *nfb,
5588 unsigned long action, void *hcpu)
5590 switch (action & ~CPU_TASKS_FROZEN) {
5591 case CPU_DOWN_PREPARE:
5592 set_cpu_active((long)hcpu, false);
5599 static int __init migration_init(void)
5601 void *cpu = (void *)(long)smp_processor_id();
5604 /* Initialize migration for the boot CPU */
5605 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5606 BUG_ON(err == NOTIFY_BAD);
5607 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5608 register_cpu_notifier(&migration_notifier);
5610 /* Register cpu active notifiers */
5611 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5612 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5616 early_initcall(migration_init);
5618 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5620 #ifdef CONFIG_SCHED_DEBUG
5622 static __read_mostly int sched_debug_enabled;
5624 static int __init sched_debug_setup(char *str)
5626 sched_debug_enabled = 1;
5630 early_param("sched_debug", sched_debug_setup);
5632 static inline bool sched_debug(void)
5634 return sched_debug_enabled;
5637 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5638 struct cpumask *groupmask)
5640 struct sched_group *group = sd->groups;
5642 cpumask_clear(groupmask);
5644 printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5646 if (!(sd->flags & SD_LOAD_BALANCE)) {
5647 printk("does not load-balance\n");
5649 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5654 printk(KERN_CONT "span %*pbl level %s\n",
5655 cpumask_pr_args(sched_domain_span(sd)), sd->name);
5657 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5658 printk(KERN_ERR "ERROR: domain->span does not contain "
5661 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5662 printk(KERN_ERR "ERROR: domain->groups does not contain"
5666 printk(KERN_DEBUG "%*s groups:", level + 1, "");
5670 printk(KERN_ERR "ERROR: group is NULL\n");
5674 if (!cpumask_weight(sched_group_cpus(group))) {
5675 printk(KERN_CONT "\n");
5676 printk(KERN_ERR "ERROR: empty group\n");
5680 if (!(sd->flags & SD_OVERLAP) &&
5681 cpumask_intersects(groupmask, sched_group_cpus(group))) {
5682 printk(KERN_CONT "\n");
5683 printk(KERN_ERR "ERROR: repeated CPUs\n");
5687 cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5689 printk(KERN_CONT " %*pbl",
5690 cpumask_pr_args(sched_group_cpus(group)));
5691 if (group->sgc->capacity != SCHED_CAPACITY_SCALE) {
5692 printk(KERN_CONT " (cpu_capacity = %d)",
5693 group->sgc->capacity);
5696 group = group->next;
5697 } while (group != sd->groups);
5698 printk(KERN_CONT "\n");
5700 if (!cpumask_equal(sched_domain_span(sd), groupmask))
5701 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5704 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5705 printk(KERN_ERR "ERROR: parent span is not a superset "
5706 "of domain->span\n");
5710 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5714 if (!sched_debug_enabled)
5718 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5722 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5725 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5733 #else /* !CONFIG_SCHED_DEBUG */
5734 # define sched_domain_debug(sd, cpu) do { } while (0)
5735 static inline bool sched_debug(void)
5739 #endif /* CONFIG_SCHED_DEBUG */
5741 static int sd_degenerate(struct sched_domain *sd)
5743 if (cpumask_weight(sched_domain_span(sd)) == 1)
5746 /* Following flags need at least 2 groups */
5747 if (sd->flags & (SD_LOAD_BALANCE |
5748 SD_BALANCE_NEWIDLE |
5751 SD_SHARE_CPUCAPACITY |
5752 SD_SHARE_PKG_RESOURCES |
5753 SD_SHARE_POWERDOMAIN)) {
5754 if (sd->groups != sd->groups->next)
5758 /* Following flags don't use groups */
5759 if (sd->flags & (SD_WAKE_AFFINE))
5766 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5768 unsigned long cflags = sd->flags, pflags = parent->flags;
5770 if (sd_degenerate(parent))
5773 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5776 /* Flags needing groups don't count if only 1 group in parent */
5777 if (parent->groups == parent->groups->next) {
5778 pflags &= ~(SD_LOAD_BALANCE |
5779 SD_BALANCE_NEWIDLE |
5782 SD_SHARE_CPUCAPACITY |
5783 SD_SHARE_PKG_RESOURCES |
5785 SD_SHARE_POWERDOMAIN);
5786 if (nr_node_ids == 1)
5787 pflags &= ~SD_SERIALIZE;
5789 if (~cflags & pflags)
5795 static void free_rootdomain(struct rcu_head *rcu)
5797 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5799 cpupri_cleanup(&rd->cpupri);
5800 cpudl_cleanup(&rd->cpudl);
5801 free_cpumask_var(rd->dlo_mask);
5802 free_cpumask_var(rd->rto_mask);
5803 free_cpumask_var(rd->online);
5804 free_cpumask_var(rd->span);
5808 static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5810 struct root_domain *old_rd = NULL;
5811 unsigned long flags;
5813 raw_spin_lock_irqsave(&rq->lock, flags);
5818 if (cpumask_test_cpu(rq->cpu, old_rd->online))
5821 cpumask_clear_cpu(rq->cpu, old_rd->span);
5824 * If we dont want to free the old_rd yet then
5825 * set old_rd to NULL to skip the freeing later
5828 if (!atomic_dec_and_test(&old_rd->refcount))
5832 atomic_inc(&rd->refcount);
5835 cpumask_set_cpu(rq->cpu, rd->span);
5836 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5839 raw_spin_unlock_irqrestore(&rq->lock, flags);
5842 call_rcu_sched(&old_rd->rcu, free_rootdomain);
5845 static int init_rootdomain(struct root_domain *rd)
5847 memset(rd, 0, sizeof(*rd));
5849 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
5851 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
5853 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
5855 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5858 init_dl_bw(&rd->dl_bw);
5859 if (cpudl_init(&rd->cpudl) != 0)
5862 if (cpupri_init(&rd->cpupri) != 0)
5867 free_cpumask_var(rd->rto_mask);
5869 free_cpumask_var(rd->dlo_mask);
5871 free_cpumask_var(rd->online);
5873 free_cpumask_var(rd->span);
5879 * By default the system creates a single root-domain with all cpus as
5880 * members (mimicking the global state we have today).
5882 struct root_domain def_root_domain;
5884 static void init_defrootdomain(void)
5886 init_rootdomain(&def_root_domain);
5888 atomic_set(&def_root_domain.refcount, 1);
5891 static struct root_domain *alloc_rootdomain(void)
5893 struct root_domain *rd;
5895 rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5899 if (init_rootdomain(rd) != 0) {
5907 static void free_sched_groups(struct sched_group *sg, int free_sgc)
5909 struct sched_group *tmp, *first;
5918 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
5923 } while (sg != first);
5926 static void free_sched_domain(struct rcu_head *rcu)
5928 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5931 * If its an overlapping domain it has private groups, iterate and
5934 if (sd->flags & SD_OVERLAP) {
5935 free_sched_groups(sd->groups, 1);
5936 } else if (atomic_dec_and_test(&sd->groups->ref)) {
5937 kfree(sd->groups->sgc);
5943 static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5945 call_rcu(&sd->rcu, free_sched_domain);
5948 static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5950 for (; sd; sd = sd->parent)
5951 destroy_sched_domain(sd, cpu);
5955 * Keep a special pointer to the highest sched_domain that has
5956 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5957 * allows us to avoid some pointer chasing select_idle_sibling().
5959 * Also keep a unique ID per domain (we use the first cpu number in
5960 * the cpumask of the domain), this allows us to quickly tell if
5961 * two cpus are in the same cache domain, see cpus_share_cache().
5963 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5964 DEFINE_PER_CPU(int, sd_llc_size);
5965 DEFINE_PER_CPU(int, sd_llc_id);
5966 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
5967 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
5968 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
5970 static void update_top_cache_domain(int cpu)
5972 struct sched_domain *sd;
5973 struct sched_domain *busy_sd = NULL;
5977 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5979 id = cpumask_first(sched_domain_span(sd));
5980 size = cpumask_weight(sched_domain_span(sd));
5981 busy_sd = sd->parent; /* sd_busy */
5983 rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd);
5985 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5986 per_cpu(sd_llc_size, cpu) = size;
5987 per_cpu(sd_llc_id, cpu) = id;
5989 sd = lowest_flag_domain(cpu, SD_NUMA);
5990 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
5992 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
5993 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
5997 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5998 * hold the hotplug lock.
6001 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
6003 struct rq *rq = cpu_rq(cpu);
6004 struct sched_domain *tmp;
6006 /* Remove the sched domains which do not contribute to scheduling. */
6007 for (tmp = sd; tmp; ) {
6008 struct sched_domain *parent = tmp->parent;
6012 if (sd_parent_degenerate(tmp, parent)) {
6013 tmp->parent = parent->parent;
6015 parent->parent->child = tmp;
6017 * Transfer SD_PREFER_SIBLING down in case of a
6018 * degenerate parent; the spans match for this
6019 * so the property transfers.
6021 if (parent->flags & SD_PREFER_SIBLING)
6022 tmp->flags |= SD_PREFER_SIBLING;
6023 destroy_sched_domain(parent, cpu);
6028 if (sd && sd_degenerate(sd)) {
6031 destroy_sched_domain(tmp, cpu);
6036 sched_domain_debug(sd, cpu);
6038 rq_attach_root(rq, rd);
6040 rcu_assign_pointer(rq->sd, sd);
6041 destroy_sched_domains(tmp, cpu);
6043 update_top_cache_domain(cpu);
6046 /* Setup the mask of cpus configured for isolated domains */
6047 static int __init isolated_cpu_setup(char *str)
6049 alloc_bootmem_cpumask_var(&cpu_isolated_map);
6050 cpulist_parse(str, cpu_isolated_map);
6054 __setup("isolcpus=", isolated_cpu_setup);
6057 struct sched_domain ** __percpu sd;
6058 struct root_domain *rd;
6069 * Build an iteration mask that can exclude certain CPUs from the upwards
6072 * Asymmetric node setups can result in situations where the domain tree is of
6073 * unequal depth, make sure to skip domains that already cover the entire
6076 * In that case build_sched_domains() will have terminated the iteration early
6077 * and our sibling sd spans will be empty. Domains should always include the
6078 * cpu they're built on, so check that.
6081 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
6083 const struct cpumask *span = sched_domain_span(sd);
6084 struct sd_data *sdd = sd->private;
6085 struct sched_domain *sibling;
6088 for_each_cpu(i, span) {
6089 sibling = *per_cpu_ptr(sdd->sd, i);
6090 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6093 cpumask_set_cpu(i, sched_group_mask(sg));
6098 * Return the canonical balance cpu for this group, this is the first cpu
6099 * of this group that's also in the iteration mask.
6101 int group_balance_cpu(struct sched_group *sg)
6103 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
6107 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
6109 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
6110 const struct cpumask *span = sched_domain_span(sd);
6111 struct cpumask *covered = sched_domains_tmpmask;
6112 struct sd_data *sdd = sd->private;
6113 struct sched_domain *sibling;
6116 cpumask_clear(covered);
6118 for_each_cpu(i, span) {
6119 struct cpumask *sg_span;
6121 if (cpumask_test_cpu(i, covered))
6124 sibling = *per_cpu_ptr(sdd->sd, i);
6126 /* See the comment near build_group_mask(). */
6127 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
6130 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6131 GFP_KERNEL, cpu_to_node(cpu));
6136 sg_span = sched_group_cpus(sg);
6138 cpumask_copy(sg_span, sched_domain_span(sibling->child));
6140 cpumask_set_cpu(i, sg_span);
6142 cpumask_or(covered, covered, sg_span);
6144 sg->sgc = *per_cpu_ptr(sdd->sgc, i);
6145 if (atomic_inc_return(&sg->sgc->ref) == 1)
6146 build_group_mask(sd, sg);
6149 * Initialize sgc->capacity such that even if we mess up the
6150 * domains and no possible iteration will get us here, we won't
6153 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
6156 * Make sure the first group of this domain contains the
6157 * canonical balance cpu. Otherwise the sched_domain iteration
6158 * breaks. See update_sg_lb_stats().
6160 if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
6161 group_balance_cpu(sg) == cpu)
6171 sd->groups = groups;
6176 free_sched_groups(first, 0);
6181 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
6183 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
6184 struct sched_domain *child = sd->child;
6187 cpu = cpumask_first(sched_domain_span(child));
6190 *sg = *per_cpu_ptr(sdd->sg, cpu);
6191 (*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
6192 atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
6199 * build_sched_groups will build a circular linked list of the groups
6200 * covered by the given span, and will set each group's ->cpumask correctly,
6201 * and ->cpu_capacity to 0.
6203 * Assumes the sched_domain tree is fully constructed
6206 build_sched_groups(struct sched_domain *sd, int cpu)
6208 struct sched_group *first = NULL, *last = NULL;
6209 struct sd_data *sdd = sd->private;
6210 const struct cpumask *span = sched_domain_span(sd);
6211 struct cpumask *covered;
6214 get_group(cpu, sdd, &sd->groups);
6215 atomic_inc(&sd->groups->ref);
6217 if (cpu != cpumask_first(span))
6220 lockdep_assert_held(&sched_domains_mutex);
6221 covered = sched_domains_tmpmask;
6223 cpumask_clear(covered);
6225 for_each_cpu(i, span) {
6226 struct sched_group *sg;
6229 if (cpumask_test_cpu(i, covered))
6232 group = get_group(i, sdd, &sg);
6233 cpumask_setall(sched_group_mask(sg));
6235 for_each_cpu(j, span) {
6236 if (get_group(j, sdd, NULL) != group)
6239 cpumask_set_cpu(j, covered);
6240 cpumask_set_cpu(j, sched_group_cpus(sg));
6255 * Initialize sched groups cpu_capacity.
6257 * cpu_capacity indicates the capacity of sched group, which is used while
6258 * distributing the load between different sched groups in a sched domain.
6259 * Typically cpu_capacity for all the groups in a sched domain will be same
6260 * unless there are asymmetries in the topology. If there are asymmetries,
6261 * group having more cpu_capacity will pickup more load compared to the
6262 * group having less cpu_capacity.
6264 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
6266 struct sched_group *sg = sd->groups;
6271 sg->group_weight = cpumask_weight(sched_group_cpus(sg));
6273 } while (sg != sd->groups);
6275 if (cpu != group_balance_cpu(sg))
6278 update_group_capacity(sd, cpu);
6279 atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
6283 * Initializers for schedule domains
6284 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6287 static int default_relax_domain_level = -1;
6288 int sched_domain_level_max;
6290 static int __init setup_relax_domain_level(char *str)
6292 if (kstrtoint(str, 0, &default_relax_domain_level))
6293 pr_warn("Unable to set relax_domain_level\n");
6297 __setup("relax_domain_level=", setup_relax_domain_level);
6299 static void set_domain_attribute(struct sched_domain *sd,
6300 struct sched_domain_attr *attr)
6304 if (!attr || attr->relax_domain_level < 0) {
6305 if (default_relax_domain_level < 0)
6308 request = default_relax_domain_level;
6310 request = attr->relax_domain_level;
6311 if (request < sd->level) {
6312 /* turn off idle balance on this domain */
6313 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6315 /* turn on idle balance on this domain */
6316 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
6320 static void __sdt_free(const struct cpumask *cpu_map);
6321 static int __sdt_alloc(const struct cpumask *cpu_map);
6323 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
6324 const struct cpumask *cpu_map)
6328 if (!atomic_read(&d->rd->refcount))
6329 free_rootdomain(&d->rd->rcu); /* fall through */
6331 free_percpu(d->sd); /* fall through */
6333 __sdt_free(cpu_map); /* fall through */
6339 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
6340 const struct cpumask *cpu_map)
6342 memset(d, 0, sizeof(*d));
6344 if (__sdt_alloc(cpu_map))
6345 return sa_sd_storage;
6346 d->sd = alloc_percpu(struct sched_domain *);
6348 return sa_sd_storage;
6349 d->rd = alloc_rootdomain();
6352 return sa_rootdomain;
6356 * NULL the sd_data elements we've used to build the sched_domain and
6357 * sched_group structure so that the subsequent __free_domain_allocs()
6358 * will not free the data we're using.
6360 static void claim_allocations(int cpu, struct sched_domain *sd)
6362 struct sd_data *sdd = sd->private;
6364 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
6365 *per_cpu_ptr(sdd->sd, cpu) = NULL;
6367 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
6368 *per_cpu_ptr(sdd->sg, cpu) = NULL;
6370 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
6371 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
6375 static int sched_domains_numa_levels;
6376 enum numa_topology_type sched_numa_topology_type;
6377 static int *sched_domains_numa_distance;
6378 int sched_max_numa_distance;
6379 static struct cpumask ***sched_domains_numa_masks;
6380 static int sched_domains_curr_level;
6384 * SD_flags allowed in topology descriptions.
6386 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6387 * SD_SHARE_PKG_RESOURCES - describes shared caches
6388 * SD_NUMA - describes NUMA topologies
6389 * SD_SHARE_POWERDOMAIN - describes shared power domain
6392 * SD_ASYM_PACKING - describes SMT quirks
6394 #define TOPOLOGY_SD_FLAGS \
6395 (SD_SHARE_CPUCAPACITY | \
6396 SD_SHARE_PKG_RESOURCES | \
6399 SD_SHARE_POWERDOMAIN)
6401 static struct sched_domain *
6402 sd_init(struct sched_domain_topology_level *tl, int cpu)
6404 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
6405 int sd_weight, sd_flags = 0;
6409 * Ugly hack to pass state to sd_numa_mask()...
6411 sched_domains_curr_level = tl->numa_level;
6414 sd_weight = cpumask_weight(tl->mask(cpu));
6417 sd_flags = (*tl->sd_flags)();
6418 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
6419 "wrong sd_flags in topology description\n"))
6420 sd_flags &= ~TOPOLOGY_SD_FLAGS;
6422 *sd = (struct sched_domain){
6423 .min_interval = sd_weight,
6424 .max_interval = 2*sd_weight,
6426 .imbalance_pct = 125,
6428 .cache_nice_tries = 0,
6435 .flags = 1*SD_LOAD_BALANCE
6436 | 1*SD_BALANCE_NEWIDLE
6441 | 0*SD_SHARE_CPUCAPACITY
6442 | 0*SD_SHARE_PKG_RESOURCES
6444 | 0*SD_PREFER_SIBLING
6449 .last_balance = jiffies,
6450 .balance_interval = sd_weight,
6452 .max_newidle_lb_cost = 0,
6453 .next_decay_max_lb_cost = jiffies,
6454 #ifdef CONFIG_SCHED_DEBUG
6460 * Convert topological properties into behaviour.
6463 if (sd->flags & SD_SHARE_CPUCAPACITY) {
6464 sd->flags |= SD_PREFER_SIBLING;
6465 sd->imbalance_pct = 110;
6466 sd->smt_gain = 1178; /* ~15% */
6468 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
6469 sd->imbalance_pct = 117;
6470 sd->cache_nice_tries = 1;
6474 } else if (sd->flags & SD_NUMA) {
6475 sd->cache_nice_tries = 2;
6479 sd->flags |= SD_SERIALIZE;
6480 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
6481 sd->flags &= ~(SD_BALANCE_EXEC |
6488 sd->flags |= SD_PREFER_SIBLING;
6489 sd->cache_nice_tries = 1;
6494 sd->private = &tl->data;
6500 * Topology list, bottom-up.
6502 static struct sched_domain_topology_level default_topology[] = {
6503 #ifdef CONFIG_SCHED_SMT
6504 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
6506 #ifdef CONFIG_SCHED_MC
6507 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
6509 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
6513 static struct sched_domain_topology_level *sched_domain_topology =
6516 #define for_each_sd_topology(tl) \
6517 for (tl = sched_domain_topology; tl->mask; tl++)
6519 void set_sched_topology(struct sched_domain_topology_level *tl)
6521 sched_domain_topology = tl;
6526 static const struct cpumask *sd_numa_mask(int cpu)
6528 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
6531 static void sched_numa_warn(const char *str)
6533 static int done = false;
6541 printk(KERN_WARNING "ERROR: %s\n\n", str);
6543 for (i = 0; i < nr_node_ids; i++) {
6544 printk(KERN_WARNING " ");
6545 for (j = 0; j < nr_node_ids; j++)
6546 printk(KERN_CONT "%02d ", node_distance(i,j));
6547 printk(KERN_CONT "\n");
6549 printk(KERN_WARNING "\n");
6552 bool find_numa_distance(int distance)
6556 if (distance == node_distance(0, 0))
6559 for (i = 0; i < sched_domains_numa_levels; i++) {
6560 if (sched_domains_numa_distance[i] == distance)
6568 * A system can have three types of NUMA topology:
6569 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6570 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6571 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6573 * The difference between a glueless mesh topology and a backplane
6574 * topology lies in whether communication between not directly
6575 * connected nodes goes through intermediary nodes (where programs
6576 * could run), or through backplane controllers. This affects
6577 * placement of programs.
6579 * The type of topology can be discerned with the following tests:
6580 * - If the maximum distance between any nodes is 1 hop, the system
6581 * is directly connected.
6582 * - If for two nodes A and B, located N > 1 hops away from each other,
6583 * there is an intermediary node C, which is < N hops away from both
6584 * nodes A and B, the system is a glueless mesh.
6586 static void init_numa_topology_type(void)
6590 n = sched_max_numa_distance;
6592 if (sched_domains_numa_levels <= 1) {
6593 sched_numa_topology_type = NUMA_DIRECT;
6597 for_each_online_node(a) {
6598 for_each_online_node(b) {
6599 /* Find two nodes furthest removed from each other. */
6600 if (node_distance(a, b) < n)
6603 /* Is there an intermediary node between a and b? */
6604 for_each_online_node(c) {
6605 if (node_distance(a, c) < n &&
6606 node_distance(b, c) < n) {
6607 sched_numa_topology_type =
6613 sched_numa_topology_type = NUMA_BACKPLANE;
6619 static void sched_init_numa(void)
6621 int next_distance, curr_distance = node_distance(0, 0);
6622 struct sched_domain_topology_level *tl;
6626 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
6627 if (!sched_domains_numa_distance)
6631 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6632 * unique distances in the node_distance() table.
6634 * Assumes node_distance(0,j) includes all distances in
6635 * node_distance(i,j) in order to avoid cubic time.
6637 next_distance = curr_distance;
6638 for (i = 0; i < nr_node_ids; i++) {
6639 for (j = 0; j < nr_node_ids; j++) {
6640 for (k = 0; k < nr_node_ids; k++) {
6641 int distance = node_distance(i, k);
6643 if (distance > curr_distance &&
6644 (distance < next_distance ||
6645 next_distance == curr_distance))
6646 next_distance = distance;
6649 * While not a strong assumption it would be nice to know
6650 * about cases where if node A is connected to B, B is not
6651 * equally connected to A.
6653 if (sched_debug() && node_distance(k, i) != distance)
6654 sched_numa_warn("Node-distance not symmetric");
6656 if (sched_debug() && i && !find_numa_distance(distance))
6657 sched_numa_warn("Node-0 not representative");
6659 if (next_distance != curr_distance) {
6660 sched_domains_numa_distance[level++] = next_distance;
6661 sched_domains_numa_levels = level;
6662 curr_distance = next_distance;
6667 * In case of sched_debug() we verify the above assumption.
6677 * 'level' contains the number of unique distances, excluding the
6678 * identity distance node_distance(i,i).
6680 * The sched_domains_numa_distance[] array includes the actual distance
6685 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6686 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6687 * the array will contain less then 'level' members. This could be
6688 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6689 * in other functions.
6691 * We reset it to 'level' at the end of this function.
6693 sched_domains_numa_levels = 0;
6695 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
6696 if (!sched_domains_numa_masks)
6700 * Now for each level, construct a mask per node which contains all
6701 * cpus of nodes that are that many hops away from us.
6703 for (i = 0; i < level; i++) {
6704 sched_domains_numa_masks[i] =
6705 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
6706 if (!sched_domains_numa_masks[i])
6709 for (j = 0; j < nr_node_ids; j++) {
6710 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
6714 sched_domains_numa_masks[i][j] = mask;
6716 for (k = 0; k < nr_node_ids; k++) {
6717 if (node_distance(j, k) > sched_domains_numa_distance[i])
6720 cpumask_or(mask, mask, cpumask_of_node(k));
6725 /* Compute default topology size */
6726 for (i = 0; sched_domain_topology[i].mask; i++);
6728 tl = kzalloc((i + level + 1) *
6729 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
6734 * Copy the default topology bits..
6736 for (i = 0; sched_domain_topology[i].mask; i++)
6737 tl[i] = sched_domain_topology[i];
6740 * .. and append 'j' levels of NUMA goodness.
6742 for (j = 0; j < level; i++, j++) {
6743 tl[i] = (struct sched_domain_topology_level){
6744 .mask = sd_numa_mask,
6745 .sd_flags = cpu_numa_flags,
6746 .flags = SDTL_OVERLAP,
6752 sched_domain_topology = tl;
6754 sched_domains_numa_levels = level;
6755 sched_max_numa_distance = sched_domains_numa_distance[level - 1];
6757 init_numa_topology_type();
6760 static void sched_domains_numa_masks_set(int cpu)
6763 int node = cpu_to_node(cpu);
6765 for (i = 0; i < sched_domains_numa_levels; i++) {
6766 for (j = 0; j < nr_node_ids; j++) {
6767 if (node_distance(j, node) <= sched_domains_numa_distance[i])
6768 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
6773 static void sched_domains_numa_masks_clear(int cpu)
6776 for (i = 0; i < sched_domains_numa_levels; i++) {
6777 for (j = 0; j < nr_node_ids; j++)
6778 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
6783 * Update sched_domains_numa_masks[level][node] array when new cpus
6786 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6787 unsigned long action,
6790 int cpu = (long)hcpu;
6792 switch (action & ~CPU_TASKS_FROZEN) {
6794 sched_domains_numa_masks_set(cpu);
6798 sched_domains_numa_masks_clear(cpu);
6808 static inline void sched_init_numa(void)
6812 static int sched_domains_numa_masks_update(struct notifier_block *nfb,
6813 unsigned long action,
6818 #endif /* CONFIG_NUMA */
6820 static int __sdt_alloc(const struct cpumask *cpu_map)
6822 struct sched_domain_topology_level *tl;
6825 for_each_sd_topology(tl) {
6826 struct sd_data *sdd = &tl->data;
6828 sdd->sd = alloc_percpu(struct sched_domain *);
6832 sdd->sg = alloc_percpu(struct sched_group *);
6836 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
6840 for_each_cpu(j, cpu_map) {
6841 struct sched_domain *sd;
6842 struct sched_group *sg;
6843 struct sched_group_capacity *sgc;
6845 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
6846 GFP_KERNEL, cpu_to_node(j));
6850 *per_cpu_ptr(sdd->sd, j) = sd;
6852 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
6853 GFP_KERNEL, cpu_to_node(j));
6859 *per_cpu_ptr(sdd->sg, j) = sg;
6861 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
6862 GFP_KERNEL, cpu_to_node(j));
6866 *per_cpu_ptr(sdd->sgc, j) = sgc;
6873 static void __sdt_free(const struct cpumask *cpu_map)
6875 struct sched_domain_topology_level *tl;
6878 for_each_sd_topology(tl) {
6879 struct sd_data *sdd = &tl->data;
6881 for_each_cpu(j, cpu_map) {
6882 struct sched_domain *sd;
6885 sd = *per_cpu_ptr(sdd->sd, j);
6886 if (sd && (sd->flags & SD_OVERLAP))
6887 free_sched_groups(sd->groups, 0);
6888 kfree(*per_cpu_ptr(sdd->sd, j));
6892 kfree(*per_cpu_ptr(sdd->sg, j));
6894 kfree(*per_cpu_ptr(sdd->sgc, j));
6896 free_percpu(sdd->sd);
6898 free_percpu(sdd->sg);
6900 free_percpu(sdd->sgc);
6905 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
6906 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
6907 struct sched_domain *child, int cpu)
6909 struct sched_domain *sd = sd_init(tl, cpu);
6913 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
6915 sd->level = child->level + 1;
6916 sched_domain_level_max = max(sched_domain_level_max, sd->level);
6920 if (!cpumask_subset(sched_domain_span(child),
6921 sched_domain_span(sd))) {
6922 pr_err("BUG: arch topology borken\n");
6923 #ifdef CONFIG_SCHED_DEBUG
6924 pr_err(" the %s domain not a subset of the %s domain\n",
6925 child->name, sd->name);
6927 /* Fixup, ensure @sd has at least @child cpus. */
6928 cpumask_or(sched_domain_span(sd),
6929 sched_domain_span(sd),
6930 sched_domain_span(child));
6934 set_domain_attribute(sd, attr);
6940 * Build sched domains for a given set of cpus and attach the sched domains
6941 * to the individual cpus
6943 static int build_sched_domains(const struct cpumask *cpu_map,
6944 struct sched_domain_attr *attr)
6946 enum s_alloc alloc_state;
6947 struct sched_domain *sd;
6949 int i, ret = -ENOMEM;
6951 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
6952 if (alloc_state != sa_rootdomain)
6955 /* Set up domains for cpus specified by the cpu_map. */
6956 for_each_cpu(i, cpu_map) {
6957 struct sched_domain_topology_level *tl;
6960 for_each_sd_topology(tl) {
6961 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
6962 if (tl == sched_domain_topology)
6963 *per_cpu_ptr(d.sd, i) = sd;
6964 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
6965 sd->flags |= SD_OVERLAP;
6966 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
6971 /* Build the groups for the domains */
6972 for_each_cpu(i, cpu_map) {
6973 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6974 sd->span_weight = cpumask_weight(sched_domain_span(sd));
6975 if (sd->flags & SD_OVERLAP) {
6976 if (build_overlap_sched_groups(sd, i))
6979 if (build_sched_groups(sd, i))
6985 /* Calculate CPU capacity for physical packages and nodes */
6986 for (i = nr_cpumask_bits-1; i >= 0; i--) {
6987 if (!cpumask_test_cpu(i, cpu_map))
6990 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
6991 claim_allocations(i, sd);
6992 init_sched_groups_capacity(i, sd);
6996 /* Attach the domains */
6998 for_each_cpu(i, cpu_map) {
6999 sd = *per_cpu_ptr(d.sd, i);
7000 cpu_attach_domain(sd, d.rd, i);
7006 __free_domain_allocs(&d, alloc_state, cpu_map);
7010 static cpumask_var_t *doms_cur; /* current sched domains */
7011 static int ndoms_cur; /* number of sched domains in 'doms_cur' */
7012 static struct sched_domain_attr *dattr_cur;
7013 /* attribues of custom domains in 'doms_cur' */
7016 * Special case: If a kmalloc of a doms_cur partition (array of
7017 * cpumask) fails, then fallback to a single sched domain,
7018 * as determined by the single cpumask fallback_doms.
7020 static cpumask_var_t fallback_doms;
7023 * arch_update_cpu_topology lets virtualized architectures update the
7024 * cpu core maps. It is supposed to return 1 if the topology changed
7025 * or 0 if it stayed the same.
7027 int __weak arch_update_cpu_topology(void)
7032 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
7035 cpumask_var_t *doms;
7037 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
7040 for (i = 0; i < ndoms; i++) {
7041 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
7042 free_sched_domains(doms, i);
7049 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
7052 for (i = 0; i < ndoms; i++)
7053 free_cpumask_var(doms[i]);
7058 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
7059 * For now this just excludes isolated cpus, but could be used to
7060 * exclude other special cases in the future.
7062 static int init_sched_domains(const struct cpumask *cpu_map)
7066 arch_update_cpu_topology();
7068 doms_cur = alloc_sched_domains(ndoms_cur);
7070 doms_cur = &fallback_doms;
7071 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
7072 err = build_sched_domains(doms_cur[0], NULL);
7073 register_sched_domain_sysctl();
7079 * Detach sched domains from a group of cpus specified in cpu_map
7080 * These cpus will now be attached to the NULL domain
7082 static void detach_destroy_domains(const struct cpumask *cpu_map)
7087 for_each_cpu(i, cpu_map)
7088 cpu_attach_domain(NULL, &def_root_domain, i);
7092 /* handle null as "default" */
7093 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
7094 struct sched_domain_attr *new, int idx_new)
7096 struct sched_domain_attr tmp;
7103 return !memcmp(cur ? (cur + idx_cur) : &tmp,
7104 new ? (new + idx_new) : &tmp,
7105 sizeof(struct sched_domain_attr));
7109 * Partition sched domains as specified by the 'ndoms_new'
7110 * cpumasks in the array doms_new[] of cpumasks. This compares
7111 * doms_new[] to the current sched domain partitioning, doms_cur[].
7112 * It destroys each deleted domain and builds each new domain.
7114 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7115 * The masks don't intersect (don't overlap.) We should setup one
7116 * sched domain for each mask. CPUs not in any of the cpumasks will
7117 * not be load balanced. If the same cpumask appears both in the
7118 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7121 * The passed in 'doms_new' should be allocated using
7122 * alloc_sched_domains. This routine takes ownership of it and will
7123 * free_sched_domains it when done with it. If the caller failed the
7124 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7125 * and partition_sched_domains() will fallback to the single partition
7126 * 'fallback_doms', it also forces the domains to be rebuilt.
7128 * If doms_new == NULL it will be replaced with cpu_online_mask.
7129 * ndoms_new == 0 is a special case for destroying existing domains,
7130 * and it will not create the default domain.
7132 * Call with hotplug lock held
7134 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
7135 struct sched_domain_attr *dattr_new)
7140 mutex_lock(&sched_domains_mutex);
7142 /* always unregister in case we don't destroy any domains */
7143 unregister_sched_domain_sysctl();
7145 /* Let architecture update cpu core mappings. */
7146 new_topology = arch_update_cpu_topology();
7148 n = doms_new ? ndoms_new : 0;
7150 /* Destroy deleted domains */
7151 for (i = 0; i < ndoms_cur; i++) {
7152 for (j = 0; j < n && !new_topology; j++) {
7153 if (cpumask_equal(doms_cur[i], doms_new[j])
7154 && dattrs_equal(dattr_cur, i, dattr_new, j))
7157 /* no match - a current sched domain not in new doms_new[] */
7158 detach_destroy_domains(doms_cur[i]);
7164 if (doms_new == NULL) {
7166 doms_new = &fallback_doms;
7167 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map);
7168 WARN_ON_ONCE(dattr_new);
7171 /* Build new domains */
7172 for (i = 0; i < ndoms_new; i++) {
7173 for (j = 0; j < n && !new_topology; j++) {
7174 if (cpumask_equal(doms_new[i], doms_cur[j])
7175 && dattrs_equal(dattr_new, i, dattr_cur, j))
7178 /* no match - add a new doms_new */
7179 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
7184 /* Remember the new sched domains */
7185 if (doms_cur != &fallback_doms)
7186 free_sched_domains(doms_cur, ndoms_cur);
7187 kfree(dattr_cur); /* kfree(NULL) is safe */
7188 doms_cur = doms_new;
7189 dattr_cur = dattr_new;
7190 ndoms_cur = ndoms_new;
7192 register_sched_domain_sysctl();
7194 mutex_unlock(&sched_domains_mutex);
7197 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
7200 * Update cpusets according to cpu_active mask. If cpusets are
7201 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7202 * around partition_sched_domains().
7204 * If we come here as part of a suspend/resume, don't touch cpusets because we
7205 * want to restore it back to its original state upon resume anyway.
7207 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
7211 case CPU_ONLINE_FROZEN:
7212 case CPU_DOWN_FAILED_FROZEN:
7215 * num_cpus_frozen tracks how many CPUs are involved in suspend
7216 * resume sequence. As long as this is not the last online
7217 * operation in the resume sequence, just build a single sched
7218 * domain, ignoring cpusets.
7221 if (likely(num_cpus_frozen)) {
7222 partition_sched_domains(1, NULL, NULL);
7227 * This is the last CPU online operation. So fall through and
7228 * restore the original sched domains by considering the
7229 * cpuset configurations.
7233 cpuset_update_active_cpus(true);
7241 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
7244 unsigned long flags;
7245 long cpu = (long)hcpu;
7251 case CPU_DOWN_PREPARE:
7252 rcu_read_lock_sched();
7253 dl_b = dl_bw_of(cpu);
7255 raw_spin_lock_irqsave(&dl_b->lock, flags);
7256 cpus = dl_bw_cpus(cpu);
7257 overflow = __dl_overflow(dl_b, cpus, 0, 0);
7258 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
7260 rcu_read_unlock_sched();
7263 return notifier_from_errno(-EBUSY);
7264 cpuset_update_active_cpus(false);
7266 case CPU_DOWN_PREPARE_FROZEN:
7268 partition_sched_domains(1, NULL, NULL);
7276 void __init sched_init_smp(void)
7278 cpumask_var_t non_isolated_cpus;
7280 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
7281 alloc_cpumask_var(&fallback_doms, GFP_KERNEL);
7286 * There's no userspace yet to cause hotplug operations; hence all the
7287 * cpu masks are stable and all blatant races in the below code cannot
7290 mutex_lock(&sched_domains_mutex);
7291 init_sched_domains(cpu_active_mask);
7292 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
7293 if (cpumask_empty(non_isolated_cpus))
7294 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);
7295 mutex_unlock(&sched_domains_mutex);
7297 hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
7298 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
7299 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);
7303 /* Move init over to a non-isolated CPU */
7304 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0)
7306 sched_init_granularity();
7307 free_cpumask_var(non_isolated_cpus);
7309 init_sched_rt_class();
7310 init_sched_dl_class();
7313 void __init sched_init_smp(void)
7315 sched_init_granularity();
7317 #endif /* CONFIG_SMP */
7319 int in_sched_functions(unsigned long addr)
7321 return in_lock_functions(addr) ||
7322 (addr >= (unsigned long)__sched_text_start
7323 && addr < (unsigned long)__sched_text_end);
7326 #ifdef CONFIG_CGROUP_SCHED
7328 * Default task group.
7329 * Every task in system belongs to this group at bootup.
7331 struct task_group root_task_group;
7332 LIST_HEAD(task_groups);
7335 DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
7337 void __init sched_init(void)
7340 unsigned long alloc_size = 0, ptr;
7342 #ifdef CONFIG_FAIR_GROUP_SCHED
7343 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7345 #ifdef CONFIG_RT_GROUP_SCHED
7346 alloc_size += 2 * nr_cpu_ids * sizeof(void **);
7349 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
7351 #ifdef CONFIG_FAIR_GROUP_SCHED
7352 root_task_group.se = (struct sched_entity **)ptr;
7353 ptr += nr_cpu_ids * sizeof(void **);
7355 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
7356 ptr += nr_cpu_ids * sizeof(void **);
7358 #endif /* CONFIG_FAIR_GROUP_SCHED */
7359 #ifdef CONFIG_RT_GROUP_SCHED
7360 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
7361 ptr += nr_cpu_ids * sizeof(void **);
7363 root_task_group.rt_rq = (struct rt_rq **)ptr;
7364 ptr += nr_cpu_ids * sizeof(void **);
7366 #endif /* CONFIG_RT_GROUP_SCHED */
7368 #ifdef CONFIG_CPUMASK_OFFSTACK
7369 for_each_possible_cpu(i) {
7370 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
7371 cpumask_size(), GFP_KERNEL, cpu_to_node(i));
7373 #endif /* CONFIG_CPUMASK_OFFSTACK */
7375 init_rt_bandwidth(&def_rt_bandwidth,
7376 global_rt_period(), global_rt_runtime());
7377 init_dl_bandwidth(&def_dl_bandwidth,
7378 global_rt_period(), global_rt_runtime());
7381 init_defrootdomain();
7384 #ifdef CONFIG_RT_GROUP_SCHED
7385 init_rt_bandwidth(&root_task_group.rt_bandwidth,
7386 global_rt_period(), global_rt_runtime());
7387 #endif /* CONFIG_RT_GROUP_SCHED */
7389 #ifdef CONFIG_CGROUP_SCHED
7390 list_add(&root_task_group.list, &task_groups);
7391 INIT_LIST_HEAD(&root_task_group.children);
7392 INIT_LIST_HEAD(&root_task_group.siblings);
7393 autogroup_init(&init_task);
7395 #endif /* CONFIG_CGROUP_SCHED */
7397 for_each_possible_cpu(i) {
7401 raw_spin_lock_init(&rq->lock);
7403 rq->calc_load_active = 0;
7404 rq->calc_load_update = jiffies + LOAD_FREQ;
7405 init_cfs_rq(&rq->cfs);
7406 init_rt_rq(&rq->rt);
7407 init_dl_rq(&rq->dl);
7408 #ifdef CONFIG_FAIR_GROUP_SCHED
7409 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
7410 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
7412 * How much cpu bandwidth does root_task_group get?
7414 * In case of task-groups formed thr' the cgroup filesystem, it
7415 * gets 100% of the cpu resources in the system. This overall
7416 * system cpu resource is divided among the tasks of
7417 * root_task_group and its child task-groups in a fair manner,
7418 * based on each entity's (task or task-group's) weight
7419 * (se->load.weight).
7421 * In other words, if root_task_group has 10 tasks of weight
7422 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7423 * then A0's share of the cpu resource is:
7425 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7427 * We achieve this by letting root_task_group's tasks sit
7428 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7430 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
7431 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
7432 #endif /* CONFIG_FAIR_GROUP_SCHED */
7434 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
7435 #ifdef CONFIG_RT_GROUP_SCHED
7436 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
7439 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
7440 rq->cpu_load[j] = 0;
7442 rq->last_load_update_tick = jiffies;
7447 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
7448 rq->balance_callback = NULL;
7449 rq->active_balance = 0;
7450 rq->next_balance = jiffies;
7455 rq->avg_idle = 2*sysctl_sched_migration_cost;
7456 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
7458 INIT_LIST_HEAD(&rq->cfs_tasks);
7460 rq_attach_root(rq, &def_root_domain);
7461 #ifdef CONFIG_NO_HZ_COMMON
7464 #ifdef CONFIG_NO_HZ_FULL
7465 rq->last_sched_tick = 0;
7469 atomic_set(&rq->nr_iowait, 0);
7472 set_load_weight(&init_task);
7474 #ifdef CONFIG_PREEMPT_NOTIFIERS
7475 INIT_HLIST_HEAD(&init_task.preempt_notifiers);
7479 * The boot idle thread does lazy MMU switching as well:
7481 atomic_inc(&init_mm.mm_count);
7482 enter_lazy_tlb(&init_mm, current);
7485 * During early bootup we pretend to be a normal task:
7487 current->sched_class = &fair_sched_class;
7490 * Make us the idle thread. Technically, schedule() should not be
7491 * called from this thread, however somewhere below it might be,
7492 * but because we are the idle thread, we just pick up running again
7493 * when this runqueue becomes "idle".
7495 init_idle(current, smp_processor_id());
7497 calc_load_update = jiffies + LOAD_FREQ;
7500 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT);
7501 /* May be allocated at isolcpus cmdline parse time */
7502 if (cpu_isolated_map == NULL)
7503 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
7504 idle_thread_set_boot_cpu();
7505 set_cpu_rq_start_time();
7507 init_sched_fair_class();
7509 scheduler_running = 1;
7512 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7513 static inline int preempt_count_equals(int preempt_offset)
7515 int nested = preempt_count() + rcu_preempt_depth();
7517 return (nested == preempt_offset);
7520 void __might_sleep(const char *file, int line, int preempt_offset)
7523 * Blocking primitives will set (and therefore destroy) current->state,
7524 * since we will exit with TASK_RUNNING make sure we enter with it,
7525 * otherwise we will destroy state.
7527 WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
7528 "do not call blocking ops when !TASK_RUNNING; "
7529 "state=%lx set at [<%p>] %pS\n",
7531 (void *)current->task_state_change,
7532 (void *)current->task_state_change);
7534 ___might_sleep(file, line, preempt_offset);
7536 EXPORT_SYMBOL(__might_sleep);
7538 void ___might_sleep(const char *file, int line, int preempt_offset)
7540 static unsigned long prev_jiffy; /* ratelimiting */
7542 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7543 if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
7544 !is_idle_task(current)) ||
7545 system_state != SYSTEM_RUNNING || oops_in_progress)
7547 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
7549 prev_jiffy = jiffies;
7552 "BUG: sleeping function called from invalid context at %s:%d\n",
7555 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7556 in_atomic(), irqs_disabled(),
7557 current->pid, current->comm);
7559 if (task_stack_end_corrupted(current))
7560 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
7562 debug_show_held_locks(current);
7563 if (irqs_disabled())
7564 print_irqtrace_events(current);
7565 #ifdef CONFIG_DEBUG_PREEMPT
7566 if (!preempt_count_equals(preempt_offset)) {
7567 pr_err("Preemption disabled at:");
7568 print_ip_sym(current->preempt_disable_ip);
7574 EXPORT_SYMBOL(___might_sleep);
7577 #ifdef CONFIG_MAGIC_SYSRQ
7578 void normalize_rt_tasks(void)
7580 struct task_struct *g, *p;
7581 struct sched_attr attr = {
7582 .sched_policy = SCHED_NORMAL,
7585 read_lock(&tasklist_lock);
7586 for_each_process_thread(g, p) {
7588 * Only normalize user tasks:
7590 if (p->flags & PF_KTHREAD)
7593 p->se.exec_start = 0;
7594 #ifdef CONFIG_SCHEDSTATS
7595 p->se.statistics.wait_start = 0;
7596 p->se.statistics.sleep_start = 0;
7597 p->se.statistics.block_start = 0;
7600 if (!dl_task(p) && !rt_task(p)) {
7602 * Renice negative nice level userspace
7605 if (task_nice(p) < 0)
7606 set_user_nice(p, 0);
7610 __sched_setscheduler(p, &attr, false, false);
7612 read_unlock(&tasklist_lock);
7615 #endif /* CONFIG_MAGIC_SYSRQ */
7617 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7619 * These functions are only useful for the IA64 MCA handling, or kdb.
7621 * They can only be called when the whole system has been
7622 * stopped - every CPU needs to be quiescent, and no scheduling
7623 * activity can take place. Using them for anything else would
7624 * be a serious bug, and as a result, they aren't even visible
7625 * under any other configuration.
7629 * curr_task - return the current task for a given cpu.
7630 * @cpu: the processor in question.
7632 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7634 * Return: The current task for @cpu.
7636 struct task_struct *curr_task(int cpu)
7638 return cpu_curr(cpu);
7641 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7645 * set_curr_task - set the current task for a given cpu.
7646 * @cpu: the processor in question.
7647 * @p: the task pointer to set.
7649 * Description: This function must only be used when non-maskable interrupts
7650 * are serviced on a separate stack. It allows the architecture to switch the
7651 * notion of the current task on a cpu in a non-blocking manner. This function
7652 * must be called with all CPU's synchronized, and interrupts disabled, the
7653 * and caller must save the original value of the current task (see
7654 * curr_task() above) and restore that value before reenabling interrupts and
7655 * re-starting the system.
7657 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7659 void set_curr_task(int cpu, struct task_struct *p)
7666 #ifdef CONFIG_CGROUP_SCHED
7667 /* task_group_lock serializes the addition/removal of task groups */
7668 static DEFINE_SPINLOCK(task_group_lock);
7670 static void free_sched_group(struct task_group *tg)
7672 free_fair_sched_group(tg);
7673 free_rt_sched_group(tg);
7678 /* allocate runqueue etc for a new task group */
7679 struct task_group *sched_create_group(struct task_group *parent)
7681 struct task_group *tg;
7683 tg = kzalloc(sizeof(*tg), GFP_KERNEL);
7685 return ERR_PTR(-ENOMEM);
7687 if (!alloc_fair_sched_group(tg, parent))
7690 if (!alloc_rt_sched_group(tg, parent))
7696 free_sched_group(tg);
7697 return ERR_PTR(-ENOMEM);
7700 void sched_online_group(struct task_group *tg, struct task_group *parent)
7702 unsigned long flags;
7704 spin_lock_irqsave(&task_group_lock, flags);
7705 list_add_rcu(&tg->list, &task_groups);
7707 WARN_ON(!parent); /* root should already exist */
7709 tg->parent = parent;
7710 INIT_LIST_HEAD(&tg->children);
7711 list_add_rcu(&tg->siblings, &parent->children);
7712 spin_unlock_irqrestore(&task_group_lock, flags);
7715 /* rcu callback to free various structures associated with a task group */
7716 static void free_sched_group_rcu(struct rcu_head *rhp)
7718 /* now it should be safe to free those cfs_rqs */
7719 free_sched_group(container_of(rhp, struct task_group, rcu));
7722 /* Destroy runqueue etc associated with a task group */
7723 void sched_destroy_group(struct task_group *tg)
7725 /* wait for possible concurrent references to cfs_rqs complete */
7726 call_rcu(&tg->rcu, free_sched_group_rcu);
7729 void sched_offline_group(struct task_group *tg)
7731 unsigned long flags;
7734 /* end participation in shares distribution */
7735 for_each_possible_cpu(i)
7736 unregister_fair_sched_group(tg, i);
7738 spin_lock_irqsave(&task_group_lock, flags);
7739 list_del_rcu(&tg->list);
7740 list_del_rcu(&tg->siblings);
7741 spin_unlock_irqrestore(&task_group_lock, flags);
7744 /* change task's runqueue when it moves between groups.
7745 * The caller of this function should have put the task in its new group
7746 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7747 * reflect its new group.
7749 void sched_move_task(struct task_struct *tsk)
7751 struct task_group *tg;
7752 int queued, running;
7753 unsigned long flags;
7756 rq = task_rq_lock(tsk, &flags);
7758 running = task_current(rq, tsk);
7759 queued = task_on_rq_queued(tsk);
7762 dequeue_task(rq, tsk, DEQUEUE_SAVE);
7763 if (unlikely(running))
7764 put_prev_task(rq, tsk);
7767 * All callers are synchronized by task_rq_lock(); we do not use RCU
7768 * which is pointless here. Thus, we pass "true" to task_css_check()
7769 * to prevent lockdep warnings.
7771 tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
7772 struct task_group, css);
7773 tg = autogroup_task_group(tsk, tg);
7774 tsk->sched_task_group = tg;
7776 #ifdef CONFIG_FAIR_GROUP_SCHED
7777 if (tsk->sched_class->task_move_group)
7778 tsk->sched_class->task_move_group(tsk);
7781 set_task_rq(tsk, task_cpu(tsk));
7783 if (unlikely(running))
7784 tsk->sched_class->set_curr_task(rq);
7786 enqueue_task(rq, tsk, ENQUEUE_RESTORE);
7788 task_rq_unlock(rq, tsk, &flags);
7790 #endif /* CONFIG_CGROUP_SCHED */
7792 #ifdef CONFIG_RT_GROUP_SCHED
7794 * Ensure that the real time constraints are schedulable.
7796 static DEFINE_MUTEX(rt_constraints_mutex);
7798 /* Must be called with tasklist_lock held */
7799 static inline int tg_has_rt_tasks(struct task_group *tg)
7801 struct task_struct *g, *p;
7804 * Autogroups do not have RT tasks; see autogroup_create().
7806 if (task_group_is_autogroup(tg))
7809 for_each_process_thread(g, p) {
7810 if (rt_task(p) && task_group(p) == tg)
7817 struct rt_schedulable_data {
7818 struct task_group *tg;
7823 static int tg_rt_schedulable(struct task_group *tg, void *data)
7825 struct rt_schedulable_data *d = data;
7826 struct task_group *child;
7827 unsigned long total, sum = 0;
7828 u64 period, runtime;
7830 period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7831 runtime = tg->rt_bandwidth.rt_runtime;
7834 period = d->rt_period;
7835 runtime = d->rt_runtime;
7839 * Cannot have more runtime than the period.
7841 if (runtime > period && runtime != RUNTIME_INF)
7845 * Ensure we don't starve existing RT tasks.
7847 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
7850 total = to_ratio(period, runtime);
7853 * Nobody can have more than the global setting allows.
7855 if (total > to_ratio(global_rt_period(), global_rt_runtime()))
7859 * The sum of our children's runtime should not exceed our own.
7861 list_for_each_entry_rcu(child, &tg->children, siblings) {
7862 period = ktime_to_ns(child->rt_bandwidth.rt_period);
7863 runtime = child->rt_bandwidth.rt_runtime;
7865 if (child == d->tg) {
7866 period = d->rt_period;
7867 runtime = d->rt_runtime;
7870 sum += to_ratio(period, runtime);
7879 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
7883 struct rt_schedulable_data data = {
7885 .rt_period = period,
7886 .rt_runtime = runtime,
7890 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
7896 static int tg_set_rt_bandwidth(struct task_group *tg,
7897 u64 rt_period, u64 rt_runtime)
7902 * Disallowing the root group RT runtime is BAD, it would disallow the
7903 * kernel creating (and or operating) RT threads.
7905 if (tg == &root_task_group && rt_runtime == 0)
7908 /* No period doesn't make any sense. */
7912 mutex_lock(&rt_constraints_mutex);
7913 read_lock(&tasklist_lock);
7914 err = __rt_schedulable(tg, rt_period, rt_runtime);
7918 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7919 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
7920 tg->rt_bandwidth.rt_runtime = rt_runtime;
7922 for_each_possible_cpu(i) {
7923 struct rt_rq *rt_rq = tg->rt_rq[i];
7925 raw_spin_lock(&rt_rq->rt_runtime_lock);
7926 rt_rq->rt_runtime = rt_runtime;
7927 raw_spin_unlock(&rt_rq->rt_runtime_lock);
7929 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
7931 read_unlock(&tasklist_lock);
7932 mutex_unlock(&rt_constraints_mutex);
7937 static int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
7939 u64 rt_runtime, rt_period;
7941 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
7942 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
7943 if (rt_runtime_us < 0)
7944 rt_runtime = RUNTIME_INF;
7946 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7949 static long sched_group_rt_runtime(struct task_group *tg)
7953 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
7956 rt_runtime_us = tg->rt_bandwidth.rt_runtime;
7957 do_div(rt_runtime_us, NSEC_PER_USEC);
7958 return rt_runtime_us;
7961 static int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
7963 u64 rt_runtime, rt_period;
7965 rt_period = rt_period_us * NSEC_PER_USEC;
7966 rt_runtime = tg->rt_bandwidth.rt_runtime;
7968 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
7971 static long sched_group_rt_period(struct task_group *tg)
7975 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
7976 do_div(rt_period_us, NSEC_PER_USEC);
7977 return rt_period_us;
7979 #endif /* CONFIG_RT_GROUP_SCHED */
7981 #ifdef CONFIG_RT_GROUP_SCHED
7982 static int sched_rt_global_constraints(void)
7986 mutex_lock(&rt_constraints_mutex);
7987 read_lock(&tasklist_lock);
7988 ret = __rt_schedulable(NULL, 0, 0);
7989 read_unlock(&tasklist_lock);
7990 mutex_unlock(&rt_constraints_mutex);
7995 static int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
7997 /* Don't accept realtime tasks when there is no way for them to run */
7998 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
8004 #else /* !CONFIG_RT_GROUP_SCHED */
8005 static int sched_rt_global_constraints(void)
8007 unsigned long flags;
8010 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
8011 for_each_possible_cpu(i) {
8012 struct rt_rq *rt_rq = &cpu_rq(i)->rt;
8014 raw_spin_lock(&rt_rq->rt_runtime_lock);
8015 rt_rq->rt_runtime = global_rt_runtime();
8016 raw_spin_unlock(&rt_rq->rt_runtime_lock);
8018 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
8022 #endif /* CONFIG_RT_GROUP_SCHED */
8024 static int sched_dl_global_validate(void)
8026 u64 runtime = global_rt_runtime();
8027 u64 period = global_rt_period();
8028 u64 new_bw = to_ratio(period, runtime);
8031 unsigned long flags;
8034 * Here we want to check the bandwidth not being set to some
8035 * value smaller than the currently allocated bandwidth in
8036 * any of the root_domains.
8038 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
8039 * cycling on root_domains... Discussion on different/better
8040 * solutions is welcome!
8042 for_each_possible_cpu(cpu) {
8043 rcu_read_lock_sched();
8044 dl_b = dl_bw_of(cpu);
8046 raw_spin_lock_irqsave(&dl_b->lock, flags);
8047 if (new_bw < dl_b->total_bw)
8049 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8051 rcu_read_unlock_sched();
8060 static void sched_dl_do_global(void)
8065 unsigned long flags;
8067 def_dl_bandwidth.dl_period = global_rt_period();
8068 def_dl_bandwidth.dl_runtime = global_rt_runtime();
8070 if (global_rt_runtime() != RUNTIME_INF)
8071 new_bw = to_ratio(global_rt_period(), global_rt_runtime());
8074 * FIXME: As above...
8076 for_each_possible_cpu(cpu) {
8077 rcu_read_lock_sched();
8078 dl_b = dl_bw_of(cpu);
8080 raw_spin_lock_irqsave(&dl_b->lock, flags);
8082 raw_spin_unlock_irqrestore(&dl_b->lock, flags);
8084 rcu_read_unlock_sched();
8088 static int sched_rt_global_validate(void)
8090 if (sysctl_sched_rt_period <= 0)
8093 if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
8094 (sysctl_sched_rt_runtime > sysctl_sched_rt_period))
8100 static void sched_rt_do_global(void)
8102 def_rt_bandwidth.rt_runtime = global_rt_runtime();
8103 def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
8106 int sched_rt_handler(struct ctl_table *table, int write,
8107 void __user *buffer, size_t *lenp,
8110 int old_period, old_runtime;
8111 static DEFINE_MUTEX(mutex);
8115 old_period = sysctl_sched_rt_period;
8116 old_runtime = sysctl_sched_rt_runtime;
8118 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8120 if (!ret && write) {
8121 ret = sched_rt_global_validate();
8125 ret = sched_dl_global_validate();
8129 ret = sched_rt_global_constraints();
8133 sched_rt_do_global();
8134 sched_dl_do_global();
8138 sysctl_sched_rt_period = old_period;
8139 sysctl_sched_rt_runtime = old_runtime;
8141 mutex_unlock(&mutex);
8146 int sched_rr_handler(struct ctl_table *table, int write,
8147 void __user *buffer, size_t *lenp,
8151 static DEFINE_MUTEX(mutex);
8154 ret = proc_dointvec(table, write, buffer, lenp, ppos);
8155 /* make sure that internally we keep jiffies */
8156 /* also, writing zero resets timeslice to default */
8157 if (!ret && write) {
8158 sched_rr_timeslice = sched_rr_timeslice <= 0 ?
8159 RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice);
8161 mutex_unlock(&mutex);
8165 #ifdef CONFIG_CGROUP_SCHED
8167 static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
8169 return css ? container_of(css, struct task_group, css) : NULL;
8172 static struct cgroup_subsys_state *
8173 cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
8175 struct task_group *parent = css_tg(parent_css);
8176 struct task_group *tg;
8179 /* This is early initialization for the top cgroup */
8180 return &root_task_group.css;
8183 tg = sched_create_group(parent);
8185 return ERR_PTR(-ENOMEM);
8190 static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
8192 struct task_group *tg = css_tg(css);
8193 struct task_group *parent = css_tg(css->parent);
8196 sched_online_group(tg, parent);
8200 static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
8202 struct task_group *tg = css_tg(css);
8204 sched_destroy_group(tg);
8207 static void cpu_cgroup_css_offline(struct cgroup_subsys_state *css)
8209 struct task_group *tg = css_tg(css);
8211 sched_offline_group(tg);
8214 static void cpu_cgroup_fork(struct task_struct *task, void *private)
8216 sched_move_task(task);
8219 static int cpu_cgroup_can_attach(struct cgroup_subsys_state *css,
8220 struct cgroup_taskset *tset)
8222 struct task_struct *task;
8224 cgroup_taskset_for_each(task, tset) {
8225 #ifdef CONFIG_RT_GROUP_SCHED
8226 if (!sched_rt_can_attach(css_tg(css), task))
8229 /* We don't support RT-tasks being in separate groups */
8230 if (task->sched_class != &fair_sched_class)
8237 static void cpu_cgroup_attach(struct cgroup_subsys_state *css,
8238 struct cgroup_taskset *tset)
8240 struct task_struct *task;
8242 cgroup_taskset_for_each(task, tset)
8243 sched_move_task(task);
8246 #ifdef CONFIG_FAIR_GROUP_SCHED
8247 static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
8248 struct cftype *cftype, u64 shareval)
8250 return sched_group_set_shares(css_tg(css), scale_load(shareval));
8253 static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
8256 struct task_group *tg = css_tg(css);
8258 return (u64) scale_load_down(tg->shares);
8261 #ifdef CONFIG_CFS_BANDWIDTH
8262 static DEFINE_MUTEX(cfs_constraints_mutex);
8264 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
8265 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
8267 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
8269 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
8271 int i, ret = 0, runtime_enabled, runtime_was_enabled;
8272 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8274 if (tg == &root_task_group)
8278 * Ensure we have at some amount of bandwidth every period. This is
8279 * to prevent reaching a state of large arrears when throttled via
8280 * entity_tick() resulting in prolonged exit starvation.
8282 if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
8286 * Likewise, bound things on the otherside by preventing insane quota
8287 * periods. This also allows us to normalize in computing quota
8290 if (period > max_cfs_quota_period)
8294 * Prevent race between setting of cfs_rq->runtime_enabled and
8295 * unthrottle_offline_cfs_rqs().
8298 mutex_lock(&cfs_constraints_mutex);
8299 ret = __cfs_schedulable(tg, period, quota);
8303 runtime_enabled = quota != RUNTIME_INF;
8304 runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
8306 * If we need to toggle cfs_bandwidth_used, off->on must occur
8307 * before making related changes, and on->off must occur afterwards
8309 if (runtime_enabled && !runtime_was_enabled)
8310 cfs_bandwidth_usage_inc();
8311 raw_spin_lock_irq(&cfs_b->lock);
8312 cfs_b->period = ns_to_ktime(period);
8313 cfs_b->quota = quota;
8315 __refill_cfs_bandwidth_runtime(cfs_b);
8316 /* restart the period timer (if active) to handle new period expiry */
8317 if (runtime_enabled)
8318 start_cfs_bandwidth(cfs_b);
8319 raw_spin_unlock_irq(&cfs_b->lock);
8321 for_each_online_cpu(i) {
8322 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
8323 struct rq *rq = cfs_rq->rq;
8325 raw_spin_lock_irq(&rq->lock);
8326 cfs_rq->runtime_enabled = runtime_enabled;
8327 cfs_rq->runtime_remaining = 0;
8329 if (cfs_rq->throttled)
8330 unthrottle_cfs_rq(cfs_rq);
8331 raw_spin_unlock_irq(&rq->lock);
8333 if (runtime_was_enabled && !runtime_enabled)
8334 cfs_bandwidth_usage_dec();
8336 mutex_unlock(&cfs_constraints_mutex);
8342 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
8346 period = ktime_to_ns(tg->cfs_bandwidth.period);
8347 if (cfs_quota_us < 0)
8348 quota = RUNTIME_INF;
8350 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
8352 return tg_set_cfs_bandwidth(tg, period, quota);
8355 long tg_get_cfs_quota(struct task_group *tg)
8359 if (tg->cfs_bandwidth.quota == RUNTIME_INF)
8362 quota_us = tg->cfs_bandwidth.quota;
8363 do_div(quota_us, NSEC_PER_USEC);
8368 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
8372 period = (u64)cfs_period_us * NSEC_PER_USEC;
8373 quota = tg->cfs_bandwidth.quota;
8375 return tg_set_cfs_bandwidth(tg, period, quota);
8378 long tg_get_cfs_period(struct task_group *tg)
8382 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
8383 do_div(cfs_period_us, NSEC_PER_USEC);
8385 return cfs_period_us;
8388 static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
8391 return tg_get_cfs_quota(css_tg(css));
8394 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
8395 struct cftype *cftype, s64 cfs_quota_us)
8397 return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
8400 static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
8403 return tg_get_cfs_period(css_tg(css));
8406 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
8407 struct cftype *cftype, u64 cfs_period_us)
8409 return tg_set_cfs_period(css_tg(css), cfs_period_us);
8412 struct cfs_schedulable_data {
8413 struct task_group *tg;
8418 * normalize group quota/period to be quota/max_period
8419 * note: units are usecs
8421 static u64 normalize_cfs_quota(struct task_group *tg,
8422 struct cfs_schedulable_data *d)
8430 period = tg_get_cfs_period(tg);
8431 quota = tg_get_cfs_quota(tg);
8434 /* note: these should typically be equivalent */
8435 if (quota == RUNTIME_INF || quota == -1)
8438 return to_ratio(period, quota);
8441 static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
8443 struct cfs_schedulable_data *d = data;
8444 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8445 s64 quota = 0, parent_quota = -1;
8448 quota = RUNTIME_INF;
8450 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
8452 quota = normalize_cfs_quota(tg, d);
8453 parent_quota = parent_b->hierarchical_quota;
8456 * ensure max(child_quota) <= parent_quota, inherit when no
8459 if (quota == RUNTIME_INF)
8460 quota = parent_quota;
8461 else if (parent_quota != RUNTIME_INF && quota > parent_quota)
8464 cfs_b->hierarchical_quota = quota;
8469 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
8472 struct cfs_schedulable_data data = {
8478 if (quota != RUNTIME_INF) {
8479 do_div(data.period, NSEC_PER_USEC);
8480 do_div(data.quota, NSEC_PER_USEC);
8484 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
8490 static int cpu_stats_show(struct seq_file *sf, void *v)
8492 struct task_group *tg = css_tg(seq_css(sf));
8493 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
8495 seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
8496 seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
8497 seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
8501 #endif /* CONFIG_CFS_BANDWIDTH */
8502 #endif /* CONFIG_FAIR_GROUP_SCHED */
8504 #ifdef CONFIG_RT_GROUP_SCHED
8505 static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
8506 struct cftype *cft, s64 val)
8508 return sched_group_set_rt_runtime(css_tg(css), val);
8511 static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
8514 return sched_group_rt_runtime(css_tg(css));
8517 static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
8518 struct cftype *cftype, u64 rt_period_us)
8520 return sched_group_set_rt_period(css_tg(css), rt_period_us);
8523 static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
8526 return sched_group_rt_period(css_tg(css));
8528 #endif /* CONFIG_RT_GROUP_SCHED */
8530 static struct cftype cpu_files[] = {
8531 #ifdef CONFIG_FAIR_GROUP_SCHED
8534 .read_u64 = cpu_shares_read_u64,
8535 .write_u64 = cpu_shares_write_u64,
8538 #ifdef CONFIG_CFS_BANDWIDTH
8540 .name = "cfs_quota_us",
8541 .read_s64 = cpu_cfs_quota_read_s64,
8542 .write_s64 = cpu_cfs_quota_write_s64,
8545 .name = "cfs_period_us",
8546 .read_u64 = cpu_cfs_period_read_u64,
8547 .write_u64 = cpu_cfs_period_write_u64,
8551 .seq_show = cpu_stats_show,
8554 #ifdef CONFIG_RT_GROUP_SCHED
8556 .name = "rt_runtime_us",
8557 .read_s64 = cpu_rt_runtime_read,
8558 .write_s64 = cpu_rt_runtime_write,
8561 .name = "rt_period_us",
8562 .read_u64 = cpu_rt_period_read_uint,
8563 .write_u64 = cpu_rt_period_write_uint,
8569 struct cgroup_subsys cpu_cgrp_subsys = {
8570 .css_alloc = cpu_cgroup_css_alloc,
8571 .css_free = cpu_cgroup_css_free,
8572 .css_online = cpu_cgroup_css_online,
8573 .css_offline = cpu_cgroup_css_offline,
8574 .fork = cpu_cgroup_fork,
8575 .can_attach = cpu_cgroup_can_attach,
8576 .attach = cpu_cgroup_attach,
8577 .legacy_cftypes = cpu_files,
8581 #endif /* CONFIG_CGROUP_SCHED */
8583 void dump_cpu_task(int cpu)
8585 pr_info("Task dump for CPU %d:\n", cpu);
8586 sched_show_task(cpu_curr(cpu));