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
29 #include <linux/kasan.h>
31 #include <linux/module.h>
32 #include <linux/nmi.h>
33 #include <linux/init.h>
34 #include <linux/uaccess.h>
35 #include <linux/highmem.h>
36 #include <linux/mmu_context.h>
37 #include <linux/interrupt.h>
38 #include <linux/capability.h>
39 #include <linux/completion.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/debug_locks.h>
42 #include <linux/perf_event.h>
43 #include <linux/security.h>
44 #include <linux/notifier.h>
45 #include <linux/profile.h>
46 #include <linux/freezer.h>
47 #include <linux/vmalloc.h>
48 #include <linux/blkdev.h>
49 #include <linux/delay.h>
50 #include <linux/pid_namespace.h>
51 #include <linux/smp.h>
52 #include <linux/threads.h>
53 #include <linux/timer.h>
54 #include <linux/rcupdate.h>
55 #include <linux/cpu.h>
56 #include <linux/cpuset.h>
57 #include <linux/percpu.h>
58 #include <linux/proc_fs.h>
59 #include <linux/seq_file.h>
60 #include <linux/sysctl.h>
61 #include <linux/syscalls.h>
62 #include <linux/times.h>
63 #include <linux/tsacct_kern.h>
64 #include <linux/kprobes.h>
65 #include <linux/delayacct.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.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/context_tracking.h>
75 #include <linux/compiler.h>
76 #include <linux/frame.h>
77 #include <linux/prefetch.h>
79 #include <asm/switch_to.h>
81 #include <asm/irq_regs.h>
82 #include <asm/mutex.h>
83 #ifdef CONFIG_PARAVIRT
84 #include <asm/paravirt.h>
88 #include "../workqueue_internal.h"
89 #include "../smpboot.h"
91 #define CREATE_TRACE_POINTS
92 #include <trace/events/sched.h>
94 DEFINE_MUTEX(sched_domains_mutex
);
95 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
97 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
99 void update_rq_clock(struct rq
*rq
)
103 lockdep_assert_held(&rq
->lock
);
105 if (rq
->clock_skip_update
& RQCF_ACT_SKIP
)
108 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
112 update_rq_clock_task(rq
, delta
);
116 * Debugging: various feature bits
119 #define SCHED_FEAT(name, enabled) \
120 (1UL << __SCHED_FEAT_##name) * enabled |
122 const_debug
unsigned int sysctl_sched_features
=
123 #include "features.h"
129 * Number of tasks to iterate in a single balance run.
130 * Limited because this is done with IRQs disabled.
132 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
135 * period over which we average the RT time consumption, measured
140 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
143 * period over which we measure -rt task cpu usage in us.
146 unsigned int sysctl_sched_rt_period
= 1000000;
148 __read_mostly
int scheduler_running
;
151 * part of the period that we allow rt tasks to run in us.
154 int sysctl_sched_rt_runtime
= 950000;
156 /* cpus with isolated domains */
157 cpumask_var_t cpu_isolated_map
;
160 * this_rq_lock - lock this runqueue and disable interrupts.
162 static struct rq
*this_rq_lock(void)
169 raw_spin_lock(&rq
->lock
);
175 * __task_rq_lock - lock the rq @p resides on.
177 struct rq
*__task_rq_lock(struct task_struct
*p
, struct rq_flags
*rf
)
182 lockdep_assert_held(&p
->pi_lock
);
186 raw_spin_lock(&rq
->lock
);
187 if (likely(rq
== task_rq(p
) && !task_on_rq_migrating(p
))) {
188 rf
->cookie
= lockdep_pin_lock(&rq
->lock
);
191 raw_spin_unlock(&rq
->lock
);
193 while (unlikely(task_on_rq_migrating(p
)))
199 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
201 struct rq
*task_rq_lock(struct task_struct
*p
, struct rq_flags
*rf
)
202 __acquires(p
->pi_lock
)
208 raw_spin_lock_irqsave(&p
->pi_lock
, rf
->flags
);
210 raw_spin_lock(&rq
->lock
);
212 * move_queued_task() task_rq_lock()
215 * [S] ->on_rq = MIGRATING [L] rq = task_rq()
216 * WMB (__set_task_cpu()) ACQUIRE (rq->lock);
217 * [S] ->cpu = new_cpu [L] task_rq()
221 * If we observe the old cpu in task_rq_lock, the acquire of
222 * the old rq->lock will fully serialize against the stores.
224 * If we observe the new cpu in task_rq_lock, the acquire will
225 * pair with the WMB to ensure we must then also see migrating.
227 if (likely(rq
== task_rq(p
) && !task_on_rq_migrating(p
))) {
228 rf
->cookie
= lockdep_pin_lock(&rq
->lock
);
231 raw_spin_unlock(&rq
->lock
);
232 raw_spin_unlock_irqrestore(&p
->pi_lock
, rf
->flags
);
234 while (unlikely(task_on_rq_migrating(p
)))
239 #ifdef CONFIG_SCHED_HRTICK
241 * Use HR-timers to deliver accurate preemption points.
244 static void hrtick_clear(struct rq
*rq
)
246 if (hrtimer_active(&rq
->hrtick_timer
))
247 hrtimer_cancel(&rq
->hrtick_timer
);
251 * High-resolution timer tick.
252 * Runs from hardirq context with interrupts disabled.
254 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
256 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
258 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
260 raw_spin_lock(&rq
->lock
);
262 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
263 raw_spin_unlock(&rq
->lock
);
265 return HRTIMER_NORESTART
;
270 static void __hrtick_restart(struct rq
*rq
)
272 struct hrtimer
*timer
= &rq
->hrtick_timer
;
274 hrtimer_start_expires(timer
, HRTIMER_MODE_ABS_PINNED
);
278 * called from hardirq (IPI) context
280 static void __hrtick_start(void *arg
)
284 raw_spin_lock(&rq
->lock
);
285 __hrtick_restart(rq
);
286 rq
->hrtick_csd_pending
= 0;
287 raw_spin_unlock(&rq
->lock
);
291 * Called to set the hrtick timer state.
293 * called with rq->lock held and irqs disabled
295 void hrtick_start(struct rq
*rq
, u64 delay
)
297 struct hrtimer
*timer
= &rq
->hrtick_timer
;
302 * Don't schedule slices shorter than 10000ns, that just
303 * doesn't make sense and can cause timer DoS.
305 delta
= max_t(s64
, delay
, 10000LL);
306 time
= ktime_add_ns(timer
->base
->get_time(), delta
);
308 hrtimer_set_expires(timer
, time
);
310 if (rq
== this_rq()) {
311 __hrtick_restart(rq
);
312 } else if (!rq
->hrtick_csd_pending
) {
313 smp_call_function_single_async(cpu_of(rq
), &rq
->hrtick_csd
);
314 rq
->hrtick_csd_pending
= 1;
320 * Called to set the hrtick timer state.
322 * called with rq->lock held and irqs disabled
324 void hrtick_start(struct rq
*rq
, u64 delay
)
327 * Don't schedule slices shorter than 10000ns, that just
328 * doesn't make sense. Rely on vruntime for fairness.
330 delay
= max_t(u64
, delay
, 10000LL);
331 hrtimer_start(&rq
->hrtick_timer
, ns_to_ktime(delay
),
332 HRTIMER_MODE_REL_PINNED
);
334 #endif /* CONFIG_SMP */
336 static void init_rq_hrtick(struct rq
*rq
)
339 rq
->hrtick_csd_pending
= 0;
341 rq
->hrtick_csd
.flags
= 0;
342 rq
->hrtick_csd
.func
= __hrtick_start
;
343 rq
->hrtick_csd
.info
= rq
;
346 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
347 rq
->hrtick_timer
.function
= hrtick
;
349 #else /* CONFIG_SCHED_HRTICK */
350 static inline void hrtick_clear(struct rq
*rq
)
354 static inline void init_rq_hrtick(struct rq
*rq
)
357 #endif /* CONFIG_SCHED_HRTICK */
360 * cmpxchg based fetch_or, macro so it works for different integer types
362 #define fetch_or(ptr, mask) \
364 typeof(ptr) _ptr = (ptr); \
365 typeof(mask) _mask = (mask); \
366 typeof(*_ptr) _old, _val = *_ptr; \
369 _old = cmpxchg(_ptr, _val, _val | _mask); \
377 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
379 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
380 * this avoids any races wrt polling state changes and thereby avoids
383 static bool set_nr_and_not_polling(struct task_struct
*p
)
385 struct thread_info
*ti
= task_thread_info(p
);
386 return !(fetch_or(&ti
->flags
, _TIF_NEED_RESCHED
) & _TIF_POLLING_NRFLAG
);
390 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
392 * If this returns true, then the idle task promises to call
393 * sched_ttwu_pending() and reschedule soon.
395 static bool set_nr_if_polling(struct task_struct
*p
)
397 struct thread_info
*ti
= task_thread_info(p
);
398 typeof(ti
->flags
) old
, val
= READ_ONCE(ti
->flags
);
401 if (!(val
& _TIF_POLLING_NRFLAG
))
403 if (val
& _TIF_NEED_RESCHED
)
405 old
= cmpxchg(&ti
->flags
, val
, val
| _TIF_NEED_RESCHED
);
414 static bool set_nr_and_not_polling(struct task_struct
*p
)
416 set_tsk_need_resched(p
);
421 static bool set_nr_if_polling(struct task_struct
*p
)
428 void wake_q_add(struct wake_q_head
*head
, struct task_struct
*task
)
430 struct wake_q_node
*node
= &task
->wake_q
;
433 * Atomically grab the task, if ->wake_q is !nil already it means
434 * its already queued (either by us or someone else) and will get the
435 * wakeup due to that.
437 * This cmpxchg() implies a full barrier, which pairs with the write
438 * barrier implied by the wakeup in wake_up_q().
440 if (cmpxchg(&node
->next
, NULL
, WAKE_Q_TAIL
))
443 get_task_struct(task
);
446 * The head is context local, there can be no concurrency.
449 head
->lastp
= &node
->next
;
452 void wake_up_q(struct wake_q_head
*head
)
454 struct wake_q_node
*node
= head
->first
;
456 while (node
!= WAKE_Q_TAIL
) {
457 struct task_struct
*task
;
459 task
= container_of(node
, struct task_struct
, wake_q
);
461 /* task can safely be re-inserted now */
463 task
->wake_q
.next
= NULL
;
466 * wake_up_process() implies a wmb() to pair with the queueing
467 * in wake_q_add() so as not to miss wakeups.
469 wake_up_process(task
);
470 put_task_struct(task
);
475 * resched_curr - mark rq's current task 'to be rescheduled now'.
477 * On UP this means the setting of the need_resched flag, on SMP it
478 * might also involve a cross-CPU call to trigger the scheduler on
481 void resched_curr(struct rq
*rq
)
483 struct task_struct
*curr
= rq
->curr
;
486 lockdep_assert_held(&rq
->lock
);
488 if (test_tsk_need_resched(curr
))
493 if (cpu
== smp_processor_id()) {
494 set_tsk_need_resched(curr
);
495 set_preempt_need_resched();
499 if (set_nr_and_not_polling(curr
))
500 smp_send_reschedule(cpu
);
502 trace_sched_wake_idle_without_ipi(cpu
);
505 void resched_cpu(int cpu
)
507 struct rq
*rq
= cpu_rq(cpu
);
510 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
513 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
517 #ifdef CONFIG_NO_HZ_COMMON
519 * In the semi idle case, use the nearest busy cpu for migrating timers
520 * from an idle cpu. This is good for power-savings.
522 * We don't do similar optimization for completely idle system, as
523 * selecting an idle cpu will add more delays to the timers than intended
524 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
526 int get_nohz_timer_target(void)
528 int i
, cpu
= smp_processor_id();
529 struct sched_domain
*sd
;
531 if (!idle_cpu(cpu
) && is_housekeeping_cpu(cpu
))
535 for_each_domain(cpu
, sd
) {
536 for_each_cpu(i
, sched_domain_span(sd
)) {
540 if (!idle_cpu(i
) && is_housekeeping_cpu(i
)) {
547 if (!is_housekeeping_cpu(cpu
))
548 cpu
= housekeeping_any_cpu();
554 * When add_timer_on() enqueues a timer into the timer wheel of an
555 * idle CPU then this timer might expire before the next timer event
556 * which is scheduled to wake up that CPU. In case of a completely
557 * idle system the next event might even be infinite time into the
558 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
559 * leaves the inner idle loop so the newly added timer is taken into
560 * account when the CPU goes back to idle and evaluates the timer
561 * wheel for the next timer event.
563 static void wake_up_idle_cpu(int cpu
)
565 struct rq
*rq
= cpu_rq(cpu
);
567 if (cpu
== smp_processor_id())
570 if (set_nr_and_not_polling(rq
->idle
))
571 smp_send_reschedule(cpu
);
573 trace_sched_wake_idle_without_ipi(cpu
);
576 static bool wake_up_full_nohz_cpu(int cpu
)
579 * We just need the target to call irq_exit() and re-evaluate
580 * the next tick. The nohz full kick at least implies that.
581 * If needed we can still optimize that later with an
584 if (tick_nohz_full_cpu(cpu
)) {
585 if (cpu
!= smp_processor_id() ||
586 tick_nohz_tick_stopped())
587 tick_nohz_full_kick_cpu(cpu
);
594 void wake_up_nohz_cpu(int cpu
)
596 if (!wake_up_full_nohz_cpu(cpu
))
597 wake_up_idle_cpu(cpu
);
600 static inline bool got_nohz_idle_kick(void)
602 int cpu
= smp_processor_id();
604 if (!test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
)))
607 if (idle_cpu(cpu
) && !need_resched())
611 * We can't run Idle Load Balance on this CPU for this time so we
612 * cancel it and clear NOHZ_BALANCE_KICK
614 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
618 #else /* CONFIG_NO_HZ_COMMON */
620 static inline bool got_nohz_idle_kick(void)
625 #endif /* CONFIG_NO_HZ_COMMON */
627 #ifdef CONFIG_NO_HZ_FULL
628 bool sched_can_stop_tick(struct rq
*rq
)
632 /* Deadline tasks, even if single, need the tick */
633 if (rq
->dl
.dl_nr_running
)
637 * If there are more than one RR tasks, we need the tick to effect the
638 * actual RR behaviour.
640 if (rq
->rt
.rr_nr_running
) {
641 if (rq
->rt
.rr_nr_running
== 1)
648 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
649 * forced preemption between FIFO tasks.
651 fifo_nr_running
= rq
->rt
.rt_nr_running
- rq
->rt
.rr_nr_running
;
656 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
657 * if there's more than one we need the tick for involuntary
660 if (rq
->nr_running
> 1)
665 #endif /* CONFIG_NO_HZ_FULL */
667 void sched_avg_update(struct rq
*rq
)
669 s64 period
= sched_avg_period();
671 while ((s64
)(rq_clock(rq
) - rq
->age_stamp
) > period
) {
673 * Inline assembly required to prevent the compiler
674 * optimising this loop into a divmod call.
675 * See __iter_div_u64_rem() for another example of this.
677 asm("" : "+rm" (rq
->age_stamp
));
678 rq
->age_stamp
+= period
;
683 #endif /* CONFIG_SMP */
685 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
686 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
688 * Iterate task_group tree rooted at *from, calling @down when first entering a
689 * node and @up when leaving it for the final time.
691 * Caller must hold rcu_lock or sufficient equivalent.
693 int walk_tg_tree_from(struct task_group
*from
,
694 tg_visitor down
, tg_visitor up
, void *data
)
696 struct task_group
*parent
, *child
;
702 ret
= (*down
)(parent
, data
);
705 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
712 ret
= (*up
)(parent
, data
);
713 if (ret
|| parent
== from
)
717 parent
= parent
->parent
;
724 int tg_nop(struct task_group
*tg
, void *data
)
730 static void set_load_weight(struct task_struct
*p
)
732 int prio
= p
->static_prio
- MAX_RT_PRIO
;
733 struct load_weight
*load
= &p
->se
.load
;
736 * SCHED_IDLE tasks get minimal weight:
738 if (idle_policy(p
->policy
)) {
739 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
740 load
->inv_weight
= WMULT_IDLEPRIO
;
744 load
->weight
= scale_load(sched_prio_to_weight
[prio
]);
745 load
->inv_weight
= sched_prio_to_wmult
[prio
];
748 static inline void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
751 if (!(flags
& ENQUEUE_RESTORE
))
752 sched_info_queued(rq
, p
);
753 p
->sched_class
->enqueue_task(rq
, p
, flags
);
756 static inline void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
759 if (!(flags
& DEQUEUE_SAVE
))
760 sched_info_dequeued(rq
, p
);
761 p
->sched_class
->dequeue_task(rq
, p
, flags
);
764 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
766 if (task_contributes_to_load(p
))
767 rq
->nr_uninterruptible
--;
769 enqueue_task(rq
, p
, flags
);
772 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
774 if (task_contributes_to_load(p
))
775 rq
->nr_uninterruptible
++;
777 dequeue_task(rq
, p
, flags
);
780 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
783 * In theory, the compile should just see 0 here, and optimize out the call
784 * to sched_rt_avg_update. But I don't trust it...
786 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
787 s64 steal
= 0, irq_delta
= 0;
789 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
790 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
793 * Since irq_time is only updated on {soft,}irq_exit, we might run into
794 * this case when a previous update_rq_clock() happened inside a
797 * When this happens, we stop ->clock_task and only update the
798 * prev_irq_time stamp to account for the part that fit, so that a next
799 * update will consume the rest. This ensures ->clock_task is
802 * It does however cause some slight miss-attribution of {soft,}irq
803 * time, a more accurate solution would be to update the irq_time using
804 * the current rq->clock timestamp, except that would require using
807 if (irq_delta
> delta
)
810 rq
->prev_irq_time
+= irq_delta
;
813 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
814 if (static_key_false((¶virt_steal_rq_enabled
))) {
815 steal
= paravirt_steal_clock(cpu_of(rq
));
816 steal
-= rq
->prev_steal_time_rq
;
818 if (unlikely(steal
> delta
))
821 rq
->prev_steal_time_rq
+= steal
;
826 rq
->clock_task
+= delta
;
828 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
829 if ((irq_delta
+ steal
) && sched_feat(NONTASK_CAPACITY
))
830 sched_rt_avg_update(rq
, irq_delta
+ steal
);
834 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
836 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
837 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
841 * Make it appear like a SCHED_FIFO task, its something
842 * userspace knows about and won't get confused about.
844 * Also, it will make PI more or less work without too
845 * much confusion -- but then, stop work should not
846 * rely on PI working anyway.
848 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
850 stop
->sched_class
= &stop_sched_class
;
853 cpu_rq(cpu
)->stop
= stop
;
857 * Reset it back to a normal scheduling class so that
858 * it can die in pieces.
860 old_stop
->sched_class
= &rt_sched_class
;
865 * __normal_prio - return the priority that is based on the static prio
867 static inline int __normal_prio(struct task_struct
*p
)
869 return p
->static_prio
;
873 * Calculate the expected normal priority: i.e. priority
874 * without taking RT-inheritance into account. Might be
875 * boosted by interactivity modifiers. Changes upon fork,
876 * setprio syscalls, and whenever the interactivity
877 * estimator recalculates.
879 static inline int normal_prio(struct task_struct
*p
)
883 if (task_has_dl_policy(p
))
884 prio
= MAX_DL_PRIO
-1;
885 else if (task_has_rt_policy(p
))
886 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
888 prio
= __normal_prio(p
);
893 * Calculate the current priority, i.e. the priority
894 * taken into account by the scheduler. This value might
895 * be boosted by RT tasks, or might be boosted by
896 * interactivity modifiers. Will be RT if the task got
897 * RT-boosted. If not then it returns p->normal_prio.
899 static int effective_prio(struct task_struct
*p
)
901 p
->normal_prio
= normal_prio(p
);
903 * If we are RT tasks or we were boosted to RT priority,
904 * keep the priority unchanged. Otherwise, update priority
905 * to the normal priority:
907 if (!rt_prio(p
->prio
))
908 return p
->normal_prio
;
913 * task_curr - is this task currently executing on a CPU?
914 * @p: the task in question.
916 * Return: 1 if the task is currently executing. 0 otherwise.
918 inline int task_curr(const struct task_struct
*p
)
920 return cpu_curr(task_cpu(p
)) == p
;
924 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
925 * use the balance_callback list if you want balancing.
927 * this means any call to check_class_changed() must be followed by a call to
928 * balance_callback().
930 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
931 const struct sched_class
*prev_class
,
934 if (prev_class
!= p
->sched_class
) {
935 if (prev_class
->switched_from
)
936 prev_class
->switched_from(rq
, p
);
938 p
->sched_class
->switched_to(rq
, p
);
939 } else if (oldprio
!= p
->prio
|| dl_task(p
))
940 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
943 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
945 const struct sched_class
*class;
947 if (p
->sched_class
== rq
->curr
->sched_class
) {
948 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
950 for_each_class(class) {
951 if (class == rq
->curr
->sched_class
)
953 if (class == p
->sched_class
) {
961 * A queue event has occurred, and we're going to schedule. In
962 * this case, we can save a useless back to back clock update.
964 if (task_on_rq_queued(rq
->curr
) && test_tsk_need_resched(rq
->curr
))
965 rq_clock_skip_update(rq
, true);
970 * This is how migration works:
972 * 1) we invoke migration_cpu_stop() on the target CPU using
974 * 2) stopper starts to run (implicitly forcing the migrated thread
976 * 3) it checks whether the migrated task is still in the wrong runqueue.
977 * 4) if it's in the wrong runqueue then the migration thread removes
978 * it and puts it into the right queue.
979 * 5) stopper completes and stop_one_cpu() returns and the migration
984 * move_queued_task - move a queued task to new rq.
986 * Returns (locked) new rq. Old rq's lock is released.
988 static struct rq
*move_queued_task(struct rq
*rq
, struct task_struct
*p
, int new_cpu
)
990 lockdep_assert_held(&rq
->lock
);
992 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
993 dequeue_task(rq
, p
, 0);
994 set_task_cpu(p
, new_cpu
);
995 raw_spin_unlock(&rq
->lock
);
997 rq
= cpu_rq(new_cpu
);
999 raw_spin_lock(&rq
->lock
);
1000 BUG_ON(task_cpu(p
) != new_cpu
);
1001 enqueue_task(rq
, p
, 0);
1002 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1003 check_preempt_curr(rq
, p
, 0);
1008 struct migration_arg
{
1009 struct task_struct
*task
;
1014 * Move (not current) task off this cpu, onto dest cpu. We're doing
1015 * this because either it can't run here any more (set_cpus_allowed()
1016 * away from this CPU, or CPU going down), or because we're
1017 * attempting to rebalance this task on exec (sched_exec).
1019 * So we race with normal scheduler movements, but that's OK, as long
1020 * as the task is no longer on this CPU.
1022 static struct rq
*__migrate_task(struct rq
*rq
, struct task_struct
*p
, int dest_cpu
)
1024 if (unlikely(!cpu_active(dest_cpu
)))
1027 /* Affinity changed (again). */
1028 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1031 rq
= move_queued_task(rq
, p
, dest_cpu
);
1037 * migration_cpu_stop - this will be executed by a highprio stopper thread
1038 * and performs thread migration by bumping thread off CPU then
1039 * 'pushing' onto another runqueue.
1041 static int migration_cpu_stop(void *data
)
1043 struct migration_arg
*arg
= data
;
1044 struct task_struct
*p
= arg
->task
;
1045 struct rq
*rq
= this_rq();
1048 * The original target cpu might have gone down and we might
1049 * be on another cpu but it doesn't matter.
1051 local_irq_disable();
1053 * We need to explicitly wake pending tasks before running
1054 * __migrate_task() such that we will not miss enforcing cpus_allowed
1055 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1057 sched_ttwu_pending();
1059 raw_spin_lock(&p
->pi_lock
);
1060 raw_spin_lock(&rq
->lock
);
1062 * If task_rq(p) != rq, it cannot be migrated here, because we're
1063 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1064 * we're holding p->pi_lock.
1066 if (task_rq(p
) == rq
&& task_on_rq_queued(p
))
1067 rq
= __migrate_task(rq
, p
, arg
->dest_cpu
);
1068 raw_spin_unlock(&rq
->lock
);
1069 raw_spin_unlock(&p
->pi_lock
);
1076 * sched_class::set_cpus_allowed must do the below, but is not required to
1077 * actually call this function.
1079 void set_cpus_allowed_common(struct task_struct
*p
, const struct cpumask
*new_mask
)
1081 cpumask_copy(&p
->cpus_allowed
, new_mask
);
1082 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
1085 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
1087 struct rq
*rq
= task_rq(p
);
1088 bool queued
, running
;
1090 lockdep_assert_held(&p
->pi_lock
);
1092 queued
= task_on_rq_queued(p
);
1093 running
= task_current(rq
, p
);
1097 * Because __kthread_bind() calls this on blocked tasks without
1100 lockdep_assert_held(&rq
->lock
);
1101 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
1104 put_prev_task(rq
, p
);
1106 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
1109 p
->sched_class
->set_curr_task(rq
);
1111 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
1115 * Change a given task's CPU affinity. Migrate the thread to a
1116 * proper CPU and schedule it away if the CPU it's executing on
1117 * is removed from the allowed bitmask.
1119 * NOTE: the caller must have a valid reference to the task, the
1120 * task must not exit() & deallocate itself prematurely. The
1121 * call is not atomic; no spinlocks may be held.
1123 static int __set_cpus_allowed_ptr(struct task_struct
*p
,
1124 const struct cpumask
*new_mask
, bool check
)
1126 const struct cpumask
*cpu_valid_mask
= cpu_active_mask
;
1127 unsigned int dest_cpu
;
1132 rq
= task_rq_lock(p
, &rf
);
1134 if (p
->flags
& PF_KTHREAD
) {
1136 * Kernel threads are allowed on online && !active CPUs
1138 cpu_valid_mask
= cpu_online_mask
;
1142 * Must re-check here, to close a race against __kthread_bind(),
1143 * sched_setaffinity() is not guaranteed to observe the flag.
1145 if (check
&& (p
->flags
& PF_NO_SETAFFINITY
)) {
1150 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
1153 if (!cpumask_intersects(new_mask
, cpu_valid_mask
)) {
1158 do_set_cpus_allowed(p
, new_mask
);
1160 if (p
->flags
& PF_KTHREAD
) {
1162 * For kernel threads that do indeed end up on online &&
1163 * !active we want to ensure they are strict per-cpu threads.
1165 WARN_ON(cpumask_intersects(new_mask
, cpu_online_mask
) &&
1166 !cpumask_intersects(new_mask
, cpu_active_mask
) &&
1167 p
->nr_cpus_allowed
!= 1);
1170 /* Can the task run on the task's current CPU? If so, we're done */
1171 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
1174 dest_cpu
= cpumask_any_and(cpu_valid_mask
, new_mask
);
1175 if (task_running(rq
, p
) || p
->state
== TASK_WAKING
) {
1176 struct migration_arg arg
= { p
, dest_cpu
};
1177 /* Need help from migration thread: drop lock and wait. */
1178 task_rq_unlock(rq
, p
, &rf
);
1179 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
1180 tlb_migrate_finish(p
->mm
);
1182 } else if (task_on_rq_queued(p
)) {
1184 * OK, since we're going to drop the lock immediately
1185 * afterwards anyway.
1187 lockdep_unpin_lock(&rq
->lock
, rf
.cookie
);
1188 rq
= move_queued_task(rq
, p
, dest_cpu
);
1189 lockdep_repin_lock(&rq
->lock
, rf
.cookie
);
1192 task_rq_unlock(rq
, p
, &rf
);
1197 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
1199 return __set_cpus_allowed_ptr(p
, new_mask
, false);
1201 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
1203 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1205 #ifdef CONFIG_SCHED_DEBUG
1207 * We should never call set_task_cpu() on a blocked task,
1208 * ttwu() will sort out the placement.
1210 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
1214 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1215 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1216 * time relying on p->on_rq.
1218 WARN_ON_ONCE(p
->state
== TASK_RUNNING
&&
1219 p
->sched_class
== &fair_sched_class
&&
1220 (p
->on_rq
&& !task_on_rq_migrating(p
)));
1222 #ifdef CONFIG_LOCKDEP
1224 * The caller should hold either p->pi_lock or rq->lock, when changing
1225 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1227 * sched_move_task() holds both and thus holding either pins the cgroup,
1230 * Furthermore, all task_rq users should acquire both locks, see
1233 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
1234 lockdep_is_held(&task_rq(p
)->lock
)));
1238 trace_sched_migrate_task(p
, new_cpu
);
1240 if (task_cpu(p
) != new_cpu
) {
1241 if (p
->sched_class
->migrate_task_rq
)
1242 p
->sched_class
->migrate_task_rq(p
);
1243 p
->se
.nr_migrations
++;
1244 perf_event_task_migrate(p
);
1247 __set_task_cpu(p
, new_cpu
);
1250 static void __migrate_swap_task(struct task_struct
*p
, int cpu
)
1252 if (task_on_rq_queued(p
)) {
1253 struct rq
*src_rq
, *dst_rq
;
1255 src_rq
= task_rq(p
);
1256 dst_rq
= cpu_rq(cpu
);
1258 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
1259 deactivate_task(src_rq
, p
, 0);
1260 set_task_cpu(p
, cpu
);
1261 activate_task(dst_rq
, p
, 0);
1262 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1263 check_preempt_curr(dst_rq
, p
, 0);
1266 * Task isn't running anymore; make it appear like we migrated
1267 * it before it went to sleep. This means on wakeup we make the
1268 * previous cpu our targer instead of where it really is.
1274 struct migration_swap_arg
{
1275 struct task_struct
*src_task
, *dst_task
;
1276 int src_cpu
, dst_cpu
;
1279 static int migrate_swap_stop(void *data
)
1281 struct migration_swap_arg
*arg
= data
;
1282 struct rq
*src_rq
, *dst_rq
;
1285 if (!cpu_active(arg
->src_cpu
) || !cpu_active(arg
->dst_cpu
))
1288 src_rq
= cpu_rq(arg
->src_cpu
);
1289 dst_rq
= cpu_rq(arg
->dst_cpu
);
1291 double_raw_lock(&arg
->src_task
->pi_lock
,
1292 &arg
->dst_task
->pi_lock
);
1293 double_rq_lock(src_rq
, dst_rq
);
1295 if (task_cpu(arg
->dst_task
) != arg
->dst_cpu
)
1298 if (task_cpu(arg
->src_task
) != arg
->src_cpu
)
1301 if (!cpumask_test_cpu(arg
->dst_cpu
, tsk_cpus_allowed(arg
->src_task
)))
1304 if (!cpumask_test_cpu(arg
->src_cpu
, tsk_cpus_allowed(arg
->dst_task
)))
1307 __migrate_swap_task(arg
->src_task
, arg
->dst_cpu
);
1308 __migrate_swap_task(arg
->dst_task
, arg
->src_cpu
);
1313 double_rq_unlock(src_rq
, dst_rq
);
1314 raw_spin_unlock(&arg
->dst_task
->pi_lock
);
1315 raw_spin_unlock(&arg
->src_task
->pi_lock
);
1321 * Cross migrate two tasks
1323 int migrate_swap(struct task_struct
*cur
, struct task_struct
*p
)
1325 struct migration_swap_arg arg
;
1328 arg
= (struct migration_swap_arg
){
1330 .src_cpu
= task_cpu(cur
),
1332 .dst_cpu
= task_cpu(p
),
1335 if (arg
.src_cpu
== arg
.dst_cpu
)
1339 * These three tests are all lockless; this is OK since all of them
1340 * will be re-checked with proper locks held further down the line.
1342 if (!cpu_active(arg
.src_cpu
) || !cpu_active(arg
.dst_cpu
))
1345 if (!cpumask_test_cpu(arg
.dst_cpu
, tsk_cpus_allowed(arg
.src_task
)))
1348 if (!cpumask_test_cpu(arg
.src_cpu
, tsk_cpus_allowed(arg
.dst_task
)))
1351 trace_sched_swap_numa(cur
, arg
.src_cpu
, p
, arg
.dst_cpu
);
1352 ret
= stop_two_cpus(arg
.dst_cpu
, arg
.src_cpu
, migrate_swap_stop
, &arg
);
1359 * wait_task_inactive - wait for a thread to unschedule.
1361 * If @match_state is nonzero, it's the @p->state value just checked and
1362 * not expected to change. If it changes, i.e. @p might have woken up,
1363 * then return zero. When we succeed in waiting for @p to be off its CPU,
1364 * we return a positive number (its total switch count). If a second call
1365 * a short while later returns the same number, the caller can be sure that
1366 * @p has remained unscheduled the whole time.
1368 * The caller must ensure that the task *will* unschedule sometime soon,
1369 * else this function might spin for a *long* time. This function can't
1370 * be called with interrupts off, or it may introduce deadlock with
1371 * smp_call_function() if an IPI is sent by the same process we are
1372 * waiting to become inactive.
1374 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1376 int running
, queued
;
1383 * We do the initial early heuristics without holding
1384 * any task-queue locks at all. We'll only try to get
1385 * the runqueue lock when things look like they will
1391 * If the task is actively running on another CPU
1392 * still, just relax and busy-wait without holding
1395 * NOTE! Since we don't hold any locks, it's not
1396 * even sure that "rq" stays as the right runqueue!
1397 * But we don't care, since "task_running()" will
1398 * return false if the runqueue has changed and p
1399 * is actually now running somewhere else!
1401 while (task_running(rq
, p
)) {
1402 if (match_state
&& unlikely(p
->state
!= match_state
))
1408 * Ok, time to look more closely! We need the rq
1409 * lock now, to be *sure*. If we're wrong, we'll
1410 * just go back and repeat.
1412 rq
= task_rq_lock(p
, &rf
);
1413 trace_sched_wait_task(p
);
1414 running
= task_running(rq
, p
);
1415 queued
= task_on_rq_queued(p
);
1417 if (!match_state
|| p
->state
== match_state
)
1418 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1419 task_rq_unlock(rq
, p
, &rf
);
1422 * If it changed from the expected state, bail out now.
1424 if (unlikely(!ncsw
))
1428 * Was it really running after all now that we
1429 * checked with the proper locks actually held?
1431 * Oops. Go back and try again..
1433 if (unlikely(running
)) {
1439 * It's not enough that it's not actively running,
1440 * it must be off the runqueue _entirely_, and not
1443 * So if it was still runnable (but just not actively
1444 * running right now), it's preempted, and we should
1445 * yield - it could be a while.
1447 if (unlikely(queued
)) {
1448 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1450 set_current_state(TASK_UNINTERRUPTIBLE
);
1451 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1456 * Ahh, all good. It wasn't running, and it wasn't
1457 * runnable, which means that it will never become
1458 * running in the future either. We're all done!
1467 * kick_process - kick a running thread to enter/exit the kernel
1468 * @p: the to-be-kicked thread
1470 * Cause a process which is running on another CPU to enter
1471 * kernel-mode, without any delay. (to get signals handled.)
1473 * NOTE: this function doesn't have to take the runqueue lock,
1474 * because all it wants to ensure is that the remote task enters
1475 * the kernel. If the IPI races and the task has been migrated
1476 * to another CPU then no harm is done and the purpose has been
1479 void kick_process(struct task_struct
*p
)
1485 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1486 smp_send_reschedule(cpu
);
1489 EXPORT_SYMBOL_GPL(kick_process
);
1492 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1494 * A few notes on cpu_active vs cpu_online:
1496 * - cpu_active must be a subset of cpu_online
1498 * - on cpu-up we allow per-cpu kthreads on the online && !active cpu,
1499 * see __set_cpus_allowed_ptr(). At this point the newly online
1500 * cpu isn't yet part of the sched domains, and balancing will not
1503 * - on cpu-down we clear cpu_active() to mask the sched domains and
1504 * avoid the load balancer to place new tasks on the to be removed
1505 * cpu. Existing tasks will remain running there and will be taken
1508 * This means that fallback selection must not select !active CPUs.
1509 * And can assume that any active CPU must be online. Conversely
1510 * select_task_rq() below may allow selection of !active CPUs in order
1511 * to satisfy the above rules.
1513 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1515 int nid
= cpu_to_node(cpu
);
1516 const struct cpumask
*nodemask
= NULL
;
1517 enum { cpuset
, possible
, fail
} state
= cpuset
;
1521 * If the node that the cpu is on has been offlined, cpu_to_node()
1522 * will return -1. There is no cpu on the node, and we should
1523 * select the cpu on the other node.
1526 nodemask
= cpumask_of_node(nid
);
1528 /* Look for allowed, online CPU in same node. */
1529 for_each_cpu(dest_cpu
, nodemask
) {
1530 if (!cpu_active(dest_cpu
))
1532 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1538 /* Any allowed, online CPU? */
1539 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1540 if (!(p
->flags
& PF_KTHREAD
) && !cpu_active(dest_cpu
))
1542 if (!cpu_online(dest_cpu
))
1547 /* No more Mr. Nice Guy. */
1550 if (IS_ENABLED(CONFIG_CPUSETS
)) {
1551 cpuset_cpus_allowed_fallback(p
);
1557 do_set_cpus_allowed(p
, cpu_possible_mask
);
1568 if (state
!= cpuset
) {
1570 * Don't tell them about moving exiting tasks or
1571 * kernel threads (both mm NULL), since they never
1574 if (p
->mm
&& printk_ratelimit()) {
1575 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1576 task_pid_nr(p
), p
->comm
, cpu
);
1584 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1587 int select_task_rq(struct task_struct
*p
, int cpu
, int sd_flags
, int wake_flags
)
1589 lockdep_assert_held(&p
->pi_lock
);
1591 if (tsk_nr_cpus_allowed(p
) > 1)
1592 cpu
= p
->sched_class
->select_task_rq(p
, cpu
, sd_flags
, wake_flags
);
1594 cpu
= cpumask_any(tsk_cpus_allowed(p
));
1597 * In order not to call set_task_cpu() on a blocking task we need
1598 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1601 * Since this is common to all placement strategies, this lives here.
1603 * [ this allows ->select_task() to simply return task_cpu(p) and
1604 * not worry about this generic constraint ]
1606 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1608 cpu
= select_fallback_rq(task_cpu(p
), p
);
1613 static void update_avg(u64
*avg
, u64 sample
)
1615 s64 diff
= sample
- *avg
;
1621 static inline int __set_cpus_allowed_ptr(struct task_struct
*p
,
1622 const struct cpumask
*new_mask
, bool check
)
1624 return set_cpus_allowed_ptr(p
, new_mask
);
1627 #endif /* CONFIG_SMP */
1630 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1632 #ifdef CONFIG_SCHEDSTATS
1633 struct rq
*rq
= this_rq();
1636 int this_cpu
= smp_processor_id();
1638 if (cpu
== this_cpu
) {
1639 schedstat_inc(rq
, ttwu_local
);
1640 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1642 struct sched_domain
*sd
;
1644 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1646 for_each_domain(this_cpu
, sd
) {
1647 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1648 schedstat_inc(sd
, ttwu_wake_remote
);
1655 if (wake_flags
& WF_MIGRATED
)
1656 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1658 #endif /* CONFIG_SMP */
1660 schedstat_inc(rq
, ttwu_count
);
1661 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1663 if (wake_flags
& WF_SYNC
)
1664 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1666 #endif /* CONFIG_SCHEDSTATS */
1669 static inline void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1671 activate_task(rq
, p
, en_flags
);
1672 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1674 /* if a worker is waking up, notify workqueue */
1675 if (p
->flags
& PF_WQ_WORKER
)
1676 wq_worker_waking_up(p
, cpu_of(rq
));
1680 * Mark the task runnable and perform wakeup-preemption.
1682 static void ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
,
1683 struct pin_cookie cookie
)
1685 check_preempt_curr(rq
, p
, wake_flags
);
1686 p
->state
= TASK_RUNNING
;
1687 trace_sched_wakeup(p
);
1690 if (p
->sched_class
->task_woken
) {
1692 * Our task @p is fully woken up and running; so its safe to
1693 * drop the rq->lock, hereafter rq is only used for statistics.
1695 lockdep_unpin_lock(&rq
->lock
, cookie
);
1696 p
->sched_class
->task_woken(rq
, p
);
1697 lockdep_repin_lock(&rq
->lock
, cookie
);
1700 if (rq
->idle_stamp
) {
1701 u64 delta
= rq_clock(rq
) - rq
->idle_stamp
;
1702 u64 max
= 2*rq
->max_idle_balance_cost
;
1704 update_avg(&rq
->avg_idle
, delta
);
1706 if (rq
->avg_idle
> max
)
1715 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
,
1716 struct pin_cookie cookie
)
1718 int en_flags
= ENQUEUE_WAKEUP
;
1720 lockdep_assert_held(&rq
->lock
);
1723 if (p
->sched_contributes_to_load
)
1724 rq
->nr_uninterruptible
--;
1726 if (wake_flags
& WF_MIGRATED
)
1727 en_flags
|= ENQUEUE_MIGRATED
;
1730 ttwu_activate(rq
, p
, en_flags
);
1731 ttwu_do_wakeup(rq
, p
, wake_flags
, cookie
);
1735 * Called in case the task @p isn't fully descheduled from its runqueue,
1736 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1737 * since all we need to do is flip p->state to TASK_RUNNING, since
1738 * the task is still ->on_rq.
1740 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1746 rq
= __task_rq_lock(p
, &rf
);
1747 if (task_on_rq_queued(p
)) {
1748 /* check_preempt_curr() may use rq clock */
1749 update_rq_clock(rq
);
1750 ttwu_do_wakeup(rq
, p
, wake_flags
, rf
.cookie
);
1753 __task_rq_unlock(rq
, &rf
);
1759 void sched_ttwu_pending(void)
1761 struct rq
*rq
= this_rq();
1762 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1763 struct pin_cookie cookie
;
1764 struct task_struct
*p
;
1765 unsigned long flags
;
1770 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1771 cookie
= lockdep_pin_lock(&rq
->lock
);
1776 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1777 llist
= llist_next(llist
);
1779 if (p
->sched_remote_wakeup
)
1780 wake_flags
= WF_MIGRATED
;
1782 ttwu_do_activate(rq
, p
, wake_flags
, cookie
);
1785 lockdep_unpin_lock(&rq
->lock
, cookie
);
1786 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1789 void scheduler_ipi(void)
1792 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1793 * TIF_NEED_RESCHED remotely (for the first time) will also send
1796 preempt_fold_need_resched();
1798 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick())
1802 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1803 * traditionally all their work was done from the interrupt return
1804 * path. Now that we actually do some work, we need to make sure
1807 * Some archs already do call them, luckily irq_enter/exit nest
1810 * Arguably we should visit all archs and update all handlers,
1811 * however a fair share of IPIs are still resched only so this would
1812 * somewhat pessimize the simple resched case.
1815 sched_ttwu_pending();
1818 * Check if someone kicked us for doing the nohz idle load balance.
1820 if (unlikely(got_nohz_idle_kick())) {
1821 this_rq()->idle_balance
= 1;
1822 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1827 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
, int wake_flags
)
1829 struct rq
*rq
= cpu_rq(cpu
);
1831 p
->sched_remote_wakeup
= !!(wake_flags
& WF_MIGRATED
);
1833 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
)) {
1834 if (!set_nr_if_polling(rq
->idle
))
1835 smp_send_reschedule(cpu
);
1837 trace_sched_wake_idle_without_ipi(cpu
);
1841 void wake_up_if_idle(int cpu
)
1843 struct rq
*rq
= cpu_rq(cpu
);
1844 unsigned long flags
;
1848 if (!is_idle_task(rcu_dereference(rq
->curr
)))
1851 if (set_nr_if_polling(rq
->idle
)) {
1852 trace_sched_wake_idle_without_ipi(cpu
);
1854 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1855 if (is_idle_task(rq
->curr
))
1856 smp_send_reschedule(cpu
);
1857 /* Else cpu is not in idle, do nothing here */
1858 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1865 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1867 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1869 #endif /* CONFIG_SMP */
1871 static void ttwu_queue(struct task_struct
*p
, int cpu
, int wake_flags
)
1873 struct rq
*rq
= cpu_rq(cpu
);
1874 struct pin_cookie cookie
;
1876 #if defined(CONFIG_SMP)
1877 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1878 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1879 ttwu_queue_remote(p
, cpu
, wake_flags
);
1884 raw_spin_lock(&rq
->lock
);
1885 cookie
= lockdep_pin_lock(&rq
->lock
);
1886 ttwu_do_activate(rq
, p
, wake_flags
, cookie
);
1887 lockdep_unpin_lock(&rq
->lock
, cookie
);
1888 raw_spin_unlock(&rq
->lock
);
1892 * Notes on Program-Order guarantees on SMP systems.
1896 * The basic program-order guarantee on SMP systems is that when a task [t]
1897 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1898 * execution on its new cpu [c1].
1900 * For migration (of runnable tasks) this is provided by the following means:
1902 * A) UNLOCK of the rq(c0)->lock scheduling out task t
1903 * B) migration for t is required to synchronize *both* rq(c0)->lock and
1904 * rq(c1)->lock (if not at the same time, then in that order).
1905 * C) LOCK of the rq(c1)->lock scheduling in task
1907 * Transitivity guarantees that B happens after A and C after B.
1908 * Note: we only require RCpc transitivity.
1909 * Note: the cpu doing B need not be c0 or c1
1918 * UNLOCK rq(0)->lock
1920 * LOCK rq(0)->lock // orders against CPU0
1922 * UNLOCK rq(0)->lock
1926 * UNLOCK rq(1)->lock
1928 * LOCK rq(1)->lock // orders against CPU2
1931 * UNLOCK rq(1)->lock
1934 * BLOCKING -- aka. SLEEP + WAKEUP
1936 * For blocking we (obviously) need to provide the same guarantee as for
1937 * migration. However the means are completely different as there is no lock
1938 * chain to provide order. Instead we do:
1940 * 1) smp_store_release(X->on_cpu, 0)
1941 * 2) smp_cond_load_acquire(!X->on_cpu)
1945 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
1947 * LOCK rq(0)->lock LOCK X->pi_lock
1950 * smp_store_release(X->on_cpu, 0);
1952 * smp_cond_load_acquire(&X->on_cpu, !VAL);
1958 * X->state = RUNNING
1959 * UNLOCK rq(2)->lock
1961 * LOCK rq(2)->lock // orders against CPU1
1964 * UNLOCK rq(2)->lock
1967 * UNLOCK rq(0)->lock
1970 * However; for wakeups there is a second guarantee we must provide, namely we
1971 * must observe the state that lead to our wakeup. That is, not only must our
1972 * task observe its own prior state, it must also observe the stores prior to
1975 * This means that any means of doing remote wakeups must order the CPU doing
1976 * the wakeup against the CPU the task is going to end up running on. This,
1977 * however, is already required for the regular Program-Order guarantee above,
1978 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire).
1983 * try_to_wake_up - wake up a thread
1984 * @p: the thread to be awakened
1985 * @state: the mask of task states that can be woken
1986 * @wake_flags: wake modifier flags (WF_*)
1988 * Put it on the run-queue if it's not already there. The "current"
1989 * thread is always on the run-queue (except when the actual
1990 * re-schedule is in progress), and as such you're allowed to do
1991 * the simpler "current->state = TASK_RUNNING" to mark yourself
1992 * runnable without the overhead of this.
1994 * Return: %true if @p was woken up, %false if it was already running.
1995 * or @state didn't match @p's state.
1998 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
2000 unsigned long flags
;
2001 int cpu
, success
= 0;
2004 * If we are going to wake up a thread waiting for CONDITION we
2005 * need to ensure that CONDITION=1 done by the caller can not be
2006 * reordered with p->state check below. This pairs with mb() in
2007 * set_current_state() the waiting thread does.
2009 smp_mb__before_spinlock();
2010 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2011 if (!(p
->state
& state
))
2014 trace_sched_waking(p
);
2016 success
= 1; /* we're going to change ->state */
2019 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
2024 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
2025 * possible to, falsely, observe p->on_cpu == 0.
2027 * One must be running (->on_cpu == 1) in order to remove oneself
2028 * from the runqueue.
2030 * [S] ->on_cpu = 1; [L] ->on_rq
2034 * [S] ->on_rq = 0; [L] ->on_cpu
2036 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
2037 * from the consecutive calls to schedule(); the first switching to our
2038 * task, the second putting it to sleep.
2043 * If the owning (remote) cpu is still in the middle of schedule() with
2044 * this task as prev, wait until its done referencing the task.
2046 * Pairs with the smp_store_release() in finish_lock_switch().
2048 * This ensures that tasks getting woken will be fully ordered against
2049 * their previous state and preserve Program Order.
2051 smp_cond_load_acquire(&p
->on_cpu
, !VAL
);
2053 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
2054 p
->state
= TASK_WAKING
;
2056 cpu
= select_task_rq(p
, p
->wake_cpu
, SD_BALANCE_WAKE
, wake_flags
);
2057 if (task_cpu(p
) != cpu
) {
2058 wake_flags
|= WF_MIGRATED
;
2059 set_task_cpu(p
, cpu
);
2061 #endif /* CONFIG_SMP */
2063 ttwu_queue(p
, cpu
, wake_flags
);
2065 if (schedstat_enabled())
2066 ttwu_stat(p
, cpu
, wake_flags
);
2068 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2074 * try_to_wake_up_local - try to wake up a local task with rq lock held
2075 * @p: the thread to be awakened
2077 * Put @p on the run-queue if it's not already there. The caller must
2078 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2081 static void try_to_wake_up_local(struct task_struct
*p
, struct pin_cookie cookie
)
2083 struct rq
*rq
= task_rq(p
);
2085 if (WARN_ON_ONCE(rq
!= this_rq()) ||
2086 WARN_ON_ONCE(p
== current
))
2089 lockdep_assert_held(&rq
->lock
);
2091 if (!raw_spin_trylock(&p
->pi_lock
)) {
2093 * This is OK, because current is on_cpu, which avoids it being
2094 * picked for load-balance and preemption/IRQs are still
2095 * disabled avoiding further scheduler activity on it and we've
2096 * not yet picked a replacement task.
2098 lockdep_unpin_lock(&rq
->lock
, cookie
);
2099 raw_spin_unlock(&rq
->lock
);
2100 raw_spin_lock(&p
->pi_lock
);
2101 raw_spin_lock(&rq
->lock
);
2102 lockdep_repin_lock(&rq
->lock
, cookie
);
2105 if (!(p
->state
& TASK_NORMAL
))
2108 trace_sched_waking(p
);
2110 if (!task_on_rq_queued(p
))
2111 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
2113 ttwu_do_wakeup(rq
, p
, 0, cookie
);
2114 if (schedstat_enabled())
2115 ttwu_stat(p
, smp_processor_id(), 0);
2117 raw_spin_unlock(&p
->pi_lock
);
2121 * wake_up_process - Wake up a specific process
2122 * @p: The process to be woken up.
2124 * Attempt to wake up the nominated process and move it to the set of runnable
2127 * Return: 1 if the process was woken up, 0 if it was already running.
2129 * It may be assumed that this function implies a write memory barrier before
2130 * changing the task state if and only if any tasks are woken up.
2132 int wake_up_process(struct task_struct
*p
)
2134 return try_to_wake_up(p
, TASK_NORMAL
, 0);
2136 EXPORT_SYMBOL(wake_up_process
);
2138 int wake_up_state(struct task_struct
*p
, unsigned int state
)
2140 return try_to_wake_up(p
, state
, 0);
2144 * This function clears the sched_dl_entity static params.
2146 void __dl_clear_params(struct task_struct
*p
)
2148 struct sched_dl_entity
*dl_se
= &p
->dl
;
2150 dl_se
->dl_runtime
= 0;
2151 dl_se
->dl_deadline
= 0;
2152 dl_se
->dl_period
= 0;
2156 dl_se
->dl_throttled
= 0;
2157 dl_se
->dl_yielded
= 0;
2161 * Perform scheduler related setup for a newly forked process p.
2162 * p is forked by current.
2164 * __sched_fork() is basic setup used by init_idle() too:
2166 static void __sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
2171 p
->se
.exec_start
= 0;
2172 p
->se
.sum_exec_runtime
= 0;
2173 p
->se
.prev_sum_exec_runtime
= 0;
2174 p
->se
.nr_migrations
= 0;
2176 INIT_LIST_HEAD(&p
->se
.group_node
);
2178 #ifdef CONFIG_FAIR_GROUP_SCHED
2179 p
->se
.cfs_rq
= NULL
;
2182 #ifdef CONFIG_SCHEDSTATS
2183 /* Even if schedstat is disabled, there should not be garbage */
2184 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
2187 RB_CLEAR_NODE(&p
->dl
.rb_node
);
2188 init_dl_task_timer(&p
->dl
);
2189 __dl_clear_params(p
);
2191 INIT_LIST_HEAD(&p
->rt
.run_list
);
2193 p
->rt
.time_slice
= sched_rr_timeslice
;
2197 #ifdef CONFIG_PREEMPT_NOTIFIERS
2198 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
2201 #ifdef CONFIG_NUMA_BALANCING
2202 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
2203 p
->mm
->numa_next_scan
= jiffies
+ msecs_to_jiffies(sysctl_numa_balancing_scan_delay
);
2204 p
->mm
->numa_scan_seq
= 0;
2207 if (clone_flags
& CLONE_VM
)
2208 p
->numa_preferred_nid
= current
->numa_preferred_nid
;
2210 p
->numa_preferred_nid
= -1;
2212 p
->node_stamp
= 0ULL;
2213 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
2214 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
2215 p
->numa_work
.next
= &p
->numa_work
;
2216 p
->numa_faults
= NULL
;
2217 p
->last_task_numa_placement
= 0;
2218 p
->last_sum_exec_runtime
= 0;
2220 p
->numa_group
= NULL
;
2221 #endif /* CONFIG_NUMA_BALANCING */
2224 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing
);
2226 #ifdef CONFIG_NUMA_BALANCING
2228 void set_numabalancing_state(bool enabled
)
2231 static_branch_enable(&sched_numa_balancing
);
2233 static_branch_disable(&sched_numa_balancing
);
2236 #ifdef CONFIG_PROC_SYSCTL
2237 int sysctl_numa_balancing(struct ctl_table
*table
, int write
,
2238 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2242 int state
= static_branch_likely(&sched_numa_balancing
);
2244 if (write
&& !capable(CAP_SYS_ADMIN
))
2249 err
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2253 set_numabalancing_state(state
);
2259 #ifdef CONFIG_SCHEDSTATS
2261 DEFINE_STATIC_KEY_FALSE(sched_schedstats
);
2262 static bool __initdata __sched_schedstats
= false;
2264 static void set_schedstats(bool enabled
)
2267 static_branch_enable(&sched_schedstats
);
2269 static_branch_disable(&sched_schedstats
);
2272 void force_schedstat_enabled(void)
2274 if (!schedstat_enabled()) {
2275 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
2276 static_branch_enable(&sched_schedstats
);
2280 static int __init
setup_schedstats(char *str
)
2287 * This code is called before jump labels have been set up, so we can't
2288 * change the static branch directly just yet. Instead set a temporary
2289 * variable so init_schedstats() can do it later.
2291 if (!strcmp(str
, "enable")) {
2292 __sched_schedstats
= true;
2294 } else if (!strcmp(str
, "disable")) {
2295 __sched_schedstats
= false;
2300 pr_warn("Unable to parse schedstats=\n");
2304 __setup("schedstats=", setup_schedstats
);
2306 static void __init
init_schedstats(void)
2308 set_schedstats(__sched_schedstats
);
2311 #ifdef CONFIG_PROC_SYSCTL
2312 int sysctl_schedstats(struct ctl_table
*table
, int write
,
2313 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2317 int state
= static_branch_likely(&sched_schedstats
);
2319 if (write
&& !capable(CAP_SYS_ADMIN
))
2324 err
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2328 set_schedstats(state
);
2331 #endif /* CONFIG_PROC_SYSCTL */
2332 #else /* !CONFIG_SCHEDSTATS */
2333 static inline void init_schedstats(void) {}
2334 #endif /* CONFIG_SCHEDSTATS */
2337 * fork()/clone()-time setup:
2339 int sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
2341 unsigned long flags
;
2342 int cpu
= get_cpu();
2344 __sched_fork(clone_flags
, p
);
2346 * We mark the process as NEW here. This guarantees that
2347 * nobody will actually run it, and a signal or other external
2348 * event cannot wake it up and insert it on the runqueue either.
2350 p
->state
= TASK_NEW
;
2353 * Make sure we do not leak PI boosting priority to the child.
2355 p
->prio
= current
->normal_prio
;
2358 * Revert to default priority/policy on fork if requested.
2360 if (unlikely(p
->sched_reset_on_fork
)) {
2361 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
2362 p
->policy
= SCHED_NORMAL
;
2363 p
->static_prio
= NICE_TO_PRIO(0);
2365 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
2366 p
->static_prio
= NICE_TO_PRIO(0);
2368 p
->prio
= p
->normal_prio
= __normal_prio(p
);
2372 * We don't need the reset flag anymore after the fork. It has
2373 * fulfilled its duty:
2375 p
->sched_reset_on_fork
= 0;
2378 if (dl_prio(p
->prio
)) {
2381 } else if (rt_prio(p
->prio
)) {
2382 p
->sched_class
= &rt_sched_class
;
2384 p
->sched_class
= &fair_sched_class
;
2387 init_entity_runnable_average(&p
->se
);
2390 * The child is not yet in the pid-hash so no cgroup attach races,
2391 * and the cgroup is pinned to this child due to cgroup_fork()
2392 * is ran before sched_fork().
2394 * Silence PROVE_RCU.
2396 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2398 * We're setting the cpu for the first time, we don't migrate,
2399 * so use __set_task_cpu().
2401 __set_task_cpu(p
, cpu
);
2402 if (p
->sched_class
->task_fork
)
2403 p
->sched_class
->task_fork(p
);
2404 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2406 #ifdef CONFIG_SCHED_INFO
2407 if (likely(sched_info_on()))
2408 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
2410 #if defined(CONFIG_SMP)
2413 init_task_preempt_count(p
);
2415 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
2416 RB_CLEAR_NODE(&p
->pushable_dl_tasks
);
2423 unsigned long to_ratio(u64 period
, u64 runtime
)
2425 if (runtime
== RUNTIME_INF
)
2429 * Doing this here saves a lot of checks in all
2430 * the calling paths, and returning zero seems
2431 * safe for them anyway.
2436 return div64_u64(runtime
<< 20, period
);
2440 inline struct dl_bw
*dl_bw_of(int i
)
2442 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2443 "sched RCU must be held");
2444 return &cpu_rq(i
)->rd
->dl_bw
;
2447 static inline int dl_bw_cpus(int i
)
2449 struct root_domain
*rd
= cpu_rq(i
)->rd
;
2452 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2453 "sched RCU must be held");
2454 for_each_cpu_and(i
, rd
->span
, cpu_active_mask
)
2460 inline struct dl_bw
*dl_bw_of(int i
)
2462 return &cpu_rq(i
)->dl
.dl_bw
;
2465 static inline int dl_bw_cpus(int i
)
2472 * We must be sure that accepting a new task (or allowing changing the
2473 * parameters of an existing one) is consistent with the bandwidth
2474 * constraints. If yes, this function also accordingly updates the currently
2475 * allocated bandwidth to reflect the new situation.
2477 * This function is called while holding p's rq->lock.
2479 * XXX we should delay bw change until the task's 0-lag point, see
2482 static int dl_overflow(struct task_struct
*p
, int policy
,
2483 const struct sched_attr
*attr
)
2486 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
2487 u64 period
= attr
->sched_period
?: attr
->sched_deadline
;
2488 u64 runtime
= attr
->sched_runtime
;
2489 u64 new_bw
= dl_policy(policy
) ? to_ratio(period
, runtime
) : 0;
2492 /* !deadline task may carry old deadline bandwidth */
2493 if (new_bw
== p
->dl
.dl_bw
&& task_has_dl_policy(p
))
2497 * Either if a task, enters, leave, or stays -deadline but changes
2498 * its parameters, we may need to update accordingly the total
2499 * allocated bandwidth of the container.
2501 raw_spin_lock(&dl_b
->lock
);
2502 cpus
= dl_bw_cpus(task_cpu(p
));
2503 if (dl_policy(policy
) && !task_has_dl_policy(p
) &&
2504 !__dl_overflow(dl_b
, cpus
, 0, new_bw
)) {
2505 __dl_add(dl_b
, new_bw
);
2507 } else if (dl_policy(policy
) && task_has_dl_policy(p
) &&
2508 !__dl_overflow(dl_b
, cpus
, p
->dl
.dl_bw
, new_bw
)) {
2509 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2510 __dl_add(dl_b
, new_bw
);
2512 } else if (!dl_policy(policy
) && task_has_dl_policy(p
)) {
2513 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2516 raw_spin_unlock(&dl_b
->lock
);
2521 extern void init_dl_bw(struct dl_bw
*dl_b
);
2524 * wake_up_new_task - wake up a newly created task for the first time.
2526 * This function will do some initial scheduler statistics housekeeping
2527 * that must be done for every newly created context, then puts the task
2528 * on the runqueue and wakes it.
2530 void wake_up_new_task(struct task_struct
*p
)
2535 raw_spin_lock_irqsave(&p
->pi_lock
, rf
.flags
);
2536 p
->state
= TASK_RUNNING
;
2539 * Fork balancing, do it here and not earlier because:
2540 * - cpus_allowed can change in the fork path
2541 * - any previously selected cpu might disappear through hotplug
2543 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
2544 * as we're not fully set-up yet.
2546 __set_task_cpu(p
, select_task_rq(p
, task_cpu(p
), SD_BALANCE_FORK
, 0));
2548 rq
= __task_rq_lock(p
, &rf
);
2549 post_init_entity_util_avg(&p
->se
);
2551 activate_task(rq
, p
, 0);
2552 p
->on_rq
= TASK_ON_RQ_QUEUED
;
2553 trace_sched_wakeup_new(p
);
2554 check_preempt_curr(rq
, p
, WF_FORK
);
2556 if (p
->sched_class
->task_woken
) {
2558 * Nothing relies on rq->lock after this, so its fine to
2561 lockdep_unpin_lock(&rq
->lock
, rf
.cookie
);
2562 p
->sched_class
->task_woken(rq
, p
);
2563 lockdep_repin_lock(&rq
->lock
, rf
.cookie
);
2566 task_rq_unlock(rq
, p
, &rf
);
2569 #ifdef CONFIG_PREEMPT_NOTIFIERS
2571 static struct static_key preempt_notifier_key
= STATIC_KEY_INIT_FALSE
;
2573 void preempt_notifier_inc(void)
2575 static_key_slow_inc(&preempt_notifier_key
);
2577 EXPORT_SYMBOL_GPL(preempt_notifier_inc
);
2579 void preempt_notifier_dec(void)
2581 static_key_slow_dec(&preempt_notifier_key
);
2583 EXPORT_SYMBOL_GPL(preempt_notifier_dec
);
2586 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2587 * @notifier: notifier struct to register
2589 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2591 if (!static_key_false(&preempt_notifier_key
))
2592 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2594 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2596 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2599 * preempt_notifier_unregister - no longer interested in preemption notifications
2600 * @notifier: notifier struct to unregister
2602 * This is *not* safe to call from within a preemption notifier.
2604 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2606 hlist_del(¬ifier
->link
);
2608 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2610 static void __fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2612 struct preempt_notifier
*notifier
;
2614 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2615 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2618 static __always_inline
void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2620 if (static_key_false(&preempt_notifier_key
))
2621 __fire_sched_in_preempt_notifiers(curr
);
2625 __fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2626 struct task_struct
*next
)
2628 struct preempt_notifier
*notifier
;
2630 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2631 notifier
->ops
->sched_out(notifier
, next
);
2634 static __always_inline
void
2635 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2636 struct task_struct
*next
)
2638 if (static_key_false(&preempt_notifier_key
))
2639 __fire_sched_out_preempt_notifiers(curr
, next
);
2642 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2644 static inline void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2649 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2650 struct task_struct
*next
)
2654 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2657 * prepare_task_switch - prepare to switch tasks
2658 * @rq: the runqueue preparing to switch
2659 * @prev: the current task that is being switched out
2660 * @next: the task we are going to switch to.
2662 * This is called with the rq lock held and interrupts off. It must
2663 * be paired with a subsequent finish_task_switch after the context
2666 * prepare_task_switch sets up locking and calls architecture specific
2670 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
2671 struct task_struct
*next
)
2673 sched_info_switch(rq
, prev
, next
);
2674 perf_event_task_sched_out(prev
, next
);
2675 fire_sched_out_preempt_notifiers(prev
, next
);
2676 prepare_lock_switch(rq
, next
);
2677 prepare_arch_switch(next
);
2681 * finish_task_switch - clean up after a task-switch
2682 * @prev: the thread we just switched away from.
2684 * finish_task_switch must be called after the context switch, paired
2685 * with a prepare_task_switch call before the context switch.
2686 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2687 * and do any other architecture-specific cleanup actions.
2689 * Note that we may have delayed dropping an mm in context_switch(). If
2690 * so, we finish that here outside of the runqueue lock. (Doing it
2691 * with the lock held can cause deadlocks; see schedule() for
2694 * The context switch have flipped the stack from under us and restored the
2695 * local variables which were saved when this task called schedule() in the
2696 * past. prev == current is still correct but we need to recalculate this_rq
2697 * because prev may have moved to another CPU.
2699 static struct rq
*finish_task_switch(struct task_struct
*prev
)
2700 __releases(rq
->lock
)
2702 struct rq
*rq
= this_rq();
2703 struct mm_struct
*mm
= rq
->prev_mm
;
2707 * The previous task will have left us with a preempt_count of 2
2708 * because it left us after:
2711 * preempt_disable(); // 1
2713 * raw_spin_lock_irq(&rq->lock) // 2
2715 * Also, see FORK_PREEMPT_COUNT.
2717 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET
,
2718 "corrupted preempt_count: %s/%d/0x%x\n",
2719 current
->comm
, current
->pid
, preempt_count()))
2720 preempt_count_set(FORK_PREEMPT_COUNT
);
2725 * A task struct has one reference for the use as "current".
2726 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2727 * schedule one last time. The schedule call will never return, and
2728 * the scheduled task must drop that reference.
2730 * We must observe prev->state before clearing prev->on_cpu (in
2731 * finish_lock_switch), otherwise a concurrent wakeup can get prev
2732 * running on another CPU and we could rave with its RUNNING -> DEAD
2733 * transition, resulting in a double drop.
2735 prev_state
= prev
->state
;
2736 vtime_task_switch(prev
);
2737 perf_event_task_sched_in(prev
, current
);
2738 finish_lock_switch(rq
, prev
);
2739 finish_arch_post_lock_switch();
2741 fire_sched_in_preempt_notifiers(current
);
2744 if (unlikely(prev_state
== TASK_DEAD
)) {
2745 if (prev
->sched_class
->task_dead
)
2746 prev
->sched_class
->task_dead(prev
);
2749 * Remove function-return probe instances associated with this
2750 * task and put them back on the free list.
2752 kprobe_flush_task(prev
);
2753 put_task_struct(prev
);
2756 tick_nohz_task_switch();
2762 /* rq->lock is NOT held, but preemption is disabled */
2763 static void __balance_callback(struct rq
*rq
)
2765 struct callback_head
*head
, *next
;
2766 void (*func
)(struct rq
*rq
);
2767 unsigned long flags
;
2769 raw_spin_lock_irqsave(&rq
->lock
, flags
);
2770 head
= rq
->balance_callback
;
2771 rq
->balance_callback
= NULL
;
2773 func
= (void (*)(struct rq
*))head
->func
;
2780 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
2783 static inline void balance_callback(struct rq
*rq
)
2785 if (unlikely(rq
->balance_callback
))
2786 __balance_callback(rq
);
2791 static inline void balance_callback(struct rq
*rq
)
2798 * schedule_tail - first thing a freshly forked thread must call.
2799 * @prev: the thread we just switched away from.
2801 asmlinkage __visible
void schedule_tail(struct task_struct
*prev
)
2802 __releases(rq
->lock
)
2807 * New tasks start with FORK_PREEMPT_COUNT, see there and
2808 * finish_task_switch() for details.
2810 * finish_task_switch() will drop rq->lock() and lower preempt_count
2811 * and the preempt_enable() will end up enabling preemption (on
2812 * PREEMPT_COUNT kernels).
2815 rq
= finish_task_switch(prev
);
2816 balance_callback(rq
);
2819 if (current
->set_child_tid
)
2820 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2824 * context_switch - switch to the new MM and the new thread's register state.
2826 static __always_inline
struct rq
*
2827 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2828 struct task_struct
*next
, struct pin_cookie cookie
)
2830 struct mm_struct
*mm
, *oldmm
;
2832 prepare_task_switch(rq
, prev
, next
);
2835 oldmm
= prev
->active_mm
;
2837 * For paravirt, this is coupled with an exit in switch_to to
2838 * combine the page table reload and the switch backend into
2841 arch_start_context_switch(prev
);
2844 next
->active_mm
= oldmm
;
2845 atomic_inc(&oldmm
->mm_count
);
2846 enter_lazy_tlb(oldmm
, next
);
2848 switch_mm_irqs_off(oldmm
, mm
, next
);
2851 prev
->active_mm
= NULL
;
2852 rq
->prev_mm
= oldmm
;
2855 * Since the runqueue lock will be released by the next
2856 * task (which is an invalid locking op but in the case
2857 * of the scheduler it's an obvious special-case), so we
2858 * do an early lockdep release here:
2860 lockdep_unpin_lock(&rq
->lock
, cookie
);
2861 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2863 /* Here we just switch the register state and the stack. */
2864 switch_to(prev
, next
, prev
);
2867 return finish_task_switch(prev
);
2871 * nr_running and nr_context_switches:
2873 * externally visible scheduler statistics: current number of runnable
2874 * threads, total number of context switches performed since bootup.
2876 unsigned long nr_running(void)
2878 unsigned long i
, sum
= 0;
2880 for_each_online_cpu(i
)
2881 sum
+= cpu_rq(i
)->nr_running
;
2887 * Check if only the current task is running on the cpu.
2889 * Caution: this function does not check that the caller has disabled
2890 * preemption, thus the result might have a time-of-check-to-time-of-use
2891 * race. The caller is responsible to use it correctly, for example:
2893 * - from a non-preemptable section (of course)
2895 * - from a thread that is bound to a single CPU
2897 * - in a loop with very short iterations (e.g. a polling loop)
2899 bool single_task_running(void)
2901 return raw_rq()->nr_running
== 1;
2903 EXPORT_SYMBOL(single_task_running
);
2905 unsigned long long nr_context_switches(void)
2908 unsigned long long sum
= 0;
2910 for_each_possible_cpu(i
)
2911 sum
+= cpu_rq(i
)->nr_switches
;
2916 unsigned long nr_iowait(void)
2918 unsigned long i
, sum
= 0;
2920 for_each_possible_cpu(i
)
2921 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2926 unsigned long nr_iowait_cpu(int cpu
)
2928 struct rq
*this = cpu_rq(cpu
);
2929 return atomic_read(&this->nr_iowait
);
2932 void get_iowait_load(unsigned long *nr_waiters
, unsigned long *load
)
2934 struct rq
*rq
= this_rq();
2935 *nr_waiters
= atomic_read(&rq
->nr_iowait
);
2936 *load
= rq
->load
.weight
;
2942 * sched_exec - execve() is a valuable balancing opportunity, because at
2943 * this point the task has the smallest effective memory and cache footprint.
2945 void sched_exec(void)
2947 struct task_struct
*p
= current
;
2948 unsigned long flags
;
2951 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2952 dest_cpu
= p
->sched_class
->select_task_rq(p
, task_cpu(p
), SD_BALANCE_EXEC
, 0);
2953 if (dest_cpu
== smp_processor_id())
2956 if (likely(cpu_active(dest_cpu
))) {
2957 struct migration_arg arg
= { p
, dest_cpu
};
2959 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2960 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2964 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2969 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2970 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2972 EXPORT_PER_CPU_SYMBOL(kstat
);
2973 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2976 * The function fair_sched_class.update_curr accesses the struct curr
2977 * and its field curr->exec_start; when called from task_sched_runtime(),
2978 * we observe a high rate of cache misses in practice.
2979 * Prefetching this data results in improved performance.
2981 static inline void prefetch_curr_exec_start(struct task_struct
*p
)
2983 #ifdef CONFIG_FAIR_GROUP_SCHED
2984 struct sched_entity
*curr
= (&p
->se
)->cfs_rq
->curr
;
2986 struct sched_entity
*curr
= (&task_rq(p
)->cfs
)->curr
;
2989 prefetch(&curr
->exec_start
);
2993 * Return accounted runtime for the task.
2994 * In case the task is currently running, return the runtime plus current's
2995 * pending runtime that have not been accounted yet.
2997 unsigned long long task_sched_runtime(struct task_struct
*p
)
3003 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
3005 * 64-bit doesn't need locks to atomically read a 64bit value.
3006 * So we have a optimization chance when the task's delta_exec is 0.
3007 * Reading ->on_cpu is racy, but this is ok.
3009 * If we race with it leaving cpu, we'll take a lock. So we're correct.
3010 * If we race with it entering cpu, unaccounted time is 0. This is
3011 * indistinguishable from the read occurring a few cycles earlier.
3012 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
3013 * been accounted, so we're correct here as well.
3015 if (!p
->on_cpu
|| !task_on_rq_queued(p
))
3016 return p
->se
.sum_exec_runtime
;
3019 rq
= task_rq_lock(p
, &rf
);
3021 * Must be ->curr _and_ ->on_rq. If dequeued, we would
3022 * project cycles that may never be accounted to this
3023 * thread, breaking clock_gettime().
3025 if (task_current(rq
, p
) && task_on_rq_queued(p
)) {
3026 prefetch_curr_exec_start(p
);
3027 update_rq_clock(rq
);
3028 p
->sched_class
->update_curr(rq
);
3030 ns
= p
->se
.sum_exec_runtime
;
3031 task_rq_unlock(rq
, p
, &rf
);
3037 * This function gets called by the timer code, with HZ frequency.
3038 * We call it with interrupts disabled.
3040 void scheduler_tick(void)
3042 int cpu
= smp_processor_id();
3043 struct rq
*rq
= cpu_rq(cpu
);
3044 struct task_struct
*curr
= rq
->curr
;
3048 raw_spin_lock(&rq
->lock
);
3049 update_rq_clock(rq
);
3050 curr
->sched_class
->task_tick(rq
, curr
, 0);
3051 cpu_load_update_active(rq
);
3052 calc_global_load_tick(rq
);
3053 raw_spin_unlock(&rq
->lock
);
3055 perf_event_task_tick();
3058 rq
->idle_balance
= idle_cpu(cpu
);
3059 trigger_load_balance(rq
);
3061 rq_last_tick_reset(rq
);
3064 #ifdef CONFIG_NO_HZ_FULL
3066 * scheduler_tick_max_deferment
3068 * Keep at least one tick per second when a single
3069 * active task is running because the scheduler doesn't
3070 * yet completely support full dynticks environment.
3072 * This makes sure that uptime, CFS vruntime, load
3073 * balancing, etc... continue to move forward, even
3074 * with a very low granularity.
3076 * Return: Maximum deferment in nanoseconds.
3078 u64
scheduler_tick_max_deferment(void)
3080 struct rq
*rq
= this_rq();
3081 unsigned long next
, now
= READ_ONCE(jiffies
);
3083 next
= rq
->last_sched_tick
+ HZ
;
3085 if (time_before_eq(next
, now
))
3088 return jiffies_to_nsecs(next
- now
);
3092 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
3093 defined(CONFIG_PREEMPT_TRACER))
3095 * If the value passed in is equal to the current preempt count
3096 * then we just disabled preemption. Start timing the latency.
3098 static inline void preempt_latency_start(int val
)
3100 if (preempt_count() == val
) {
3101 unsigned long ip
= get_lock_parent_ip();
3102 #ifdef CONFIG_DEBUG_PREEMPT
3103 current
->preempt_disable_ip
= ip
;
3105 trace_preempt_off(CALLER_ADDR0
, ip
);
3109 void preempt_count_add(int val
)
3111 #ifdef CONFIG_DEBUG_PREEMPT
3115 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3118 __preempt_count_add(val
);
3119 #ifdef CONFIG_DEBUG_PREEMPT
3121 * Spinlock count overflowing soon?
3123 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3126 preempt_latency_start(val
);
3128 EXPORT_SYMBOL(preempt_count_add
);
3129 NOKPROBE_SYMBOL(preempt_count_add
);
3132 * If the value passed in equals to the current preempt count
3133 * then we just enabled preemption. Stop timing the latency.
3135 static inline void preempt_latency_stop(int val
)
3137 if (preempt_count() == val
)
3138 trace_preempt_on(CALLER_ADDR0
, get_lock_parent_ip());
3141 void preempt_count_sub(int val
)
3143 #ifdef CONFIG_DEBUG_PREEMPT
3147 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3150 * Is the spinlock portion underflowing?
3152 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3153 !(preempt_count() & PREEMPT_MASK
)))
3157 preempt_latency_stop(val
);
3158 __preempt_count_sub(val
);
3160 EXPORT_SYMBOL(preempt_count_sub
);
3161 NOKPROBE_SYMBOL(preempt_count_sub
);
3164 static inline void preempt_latency_start(int val
) { }
3165 static inline void preempt_latency_stop(int val
) { }
3169 * Print scheduling while atomic bug:
3171 static noinline
void __schedule_bug(struct task_struct
*prev
)
3173 if (oops_in_progress
)
3176 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3177 prev
->comm
, prev
->pid
, preempt_count());
3179 debug_show_held_locks(prev
);
3181 if (irqs_disabled())
3182 print_irqtrace_events(prev
);
3183 #ifdef CONFIG_DEBUG_PREEMPT
3184 if (in_atomic_preempt_off()) {
3185 pr_err("Preemption disabled at:");
3186 print_ip_sym(current
->preempt_disable_ip
);
3191 panic("scheduling while atomic\n");
3194 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
3198 * Various schedule()-time debugging checks and statistics:
3200 static inline void schedule_debug(struct task_struct
*prev
)
3202 #ifdef CONFIG_SCHED_STACK_END_CHECK
3203 if (task_stack_end_corrupted(prev
))
3204 panic("corrupted stack end detected inside scheduler\n");
3207 if (unlikely(in_atomic_preempt_off())) {
3208 __schedule_bug(prev
);
3209 preempt_count_set(PREEMPT_DISABLED
);
3213 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3215 schedstat_inc(this_rq(), sched_count
);
3219 * Pick up the highest-prio task:
3221 static inline struct task_struct
*
3222 pick_next_task(struct rq
*rq
, struct task_struct
*prev
, struct pin_cookie cookie
)
3224 const struct sched_class
*class = &fair_sched_class
;
3225 struct task_struct
*p
;
3228 * Optimization: we know that if all tasks are in
3229 * the fair class we can call that function directly:
3231 if (likely(prev
->sched_class
== class &&
3232 rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
3233 p
= fair_sched_class
.pick_next_task(rq
, prev
, cookie
);
3234 if (unlikely(p
== RETRY_TASK
))
3237 /* assumes fair_sched_class->next == idle_sched_class */
3239 p
= idle_sched_class
.pick_next_task(rq
, prev
, cookie
);
3245 for_each_class(class) {
3246 p
= class->pick_next_task(rq
, prev
, cookie
);
3248 if (unlikely(p
== RETRY_TASK
))
3254 BUG(); /* the idle class will always have a runnable task */
3258 * __schedule() is the main scheduler function.
3260 * The main means of driving the scheduler and thus entering this function are:
3262 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3264 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3265 * paths. For example, see arch/x86/entry_64.S.
3267 * To drive preemption between tasks, the scheduler sets the flag in timer
3268 * interrupt handler scheduler_tick().
3270 * 3. Wakeups don't really cause entry into schedule(). They add a
3271 * task to the run-queue and that's it.
3273 * Now, if the new task added to the run-queue preempts the current
3274 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3275 * called on the nearest possible occasion:
3277 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3279 * - in syscall or exception context, at the next outmost
3280 * preempt_enable(). (this might be as soon as the wake_up()'s
3283 * - in IRQ context, return from interrupt-handler to
3284 * preemptible context
3286 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3289 * - cond_resched() call
3290 * - explicit schedule() call
3291 * - return from syscall or exception to user-space
3292 * - return from interrupt-handler to user-space
3294 * WARNING: must be called with preemption disabled!
3296 static void __sched notrace
__schedule(bool preempt
)
3298 struct task_struct
*prev
, *next
;
3299 unsigned long *switch_count
;
3300 struct pin_cookie cookie
;
3304 cpu
= smp_processor_id();
3309 * do_exit() calls schedule() with preemption disabled as an exception;
3310 * however we must fix that up, otherwise the next task will see an
3311 * inconsistent (higher) preempt count.
3313 * It also avoids the below schedule_debug() test from complaining
3316 if (unlikely(prev
->state
== TASK_DEAD
))
3317 preempt_enable_no_resched_notrace();
3319 schedule_debug(prev
);
3321 if (sched_feat(HRTICK
))
3324 local_irq_disable();
3325 rcu_note_context_switch();
3328 * Make sure that signal_pending_state()->signal_pending() below
3329 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3330 * done by the caller to avoid the race with signal_wake_up().
3332 smp_mb__before_spinlock();
3333 raw_spin_lock(&rq
->lock
);
3334 cookie
= lockdep_pin_lock(&rq
->lock
);
3336 rq
->clock_skip_update
<<= 1; /* promote REQ to ACT */
3338 switch_count
= &prev
->nivcsw
;
3339 if (!preempt
&& prev
->state
) {
3340 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
3341 prev
->state
= TASK_RUNNING
;
3343 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
3347 * If a worker went to sleep, notify and ask workqueue
3348 * whether it wants to wake up a task to maintain
3351 if (prev
->flags
& PF_WQ_WORKER
) {
3352 struct task_struct
*to_wakeup
;
3354 to_wakeup
= wq_worker_sleeping(prev
);
3356 try_to_wake_up_local(to_wakeup
, cookie
);
3359 switch_count
= &prev
->nvcsw
;
3362 if (task_on_rq_queued(prev
))
3363 update_rq_clock(rq
);
3365 next
= pick_next_task(rq
, prev
, cookie
);
3366 clear_tsk_need_resched(prev
);
3367 clear_preempt_need_resched();
3368 rq
->clock_skip_update
= 0;
3370 if (likely(prev
!= next
)) {
3375 trace_sched_switch(preempt
, prev
, next
);
3376 rq
= context_switch(rq
, prev
, next
, cookie
); /* unlocks the rq */
3378 lockdep_unpin_lock(&rq
->lock
, cookie
);
3379 raw_spin_unlock_irq(&rq
->lock
);
3382 balance_callback(rq
);
3384 STACK_FRAME_NON_STANDARD(__schedule
); /* switch_to() */
3386 static inline void sched_submit_work(struct task_struct
*tsk
)
3388 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
3391 * If we are going to sleep and we have plugged IO queued,
3392 * make sure to submit it to avoid deadlocks.
3394 if (blk_needs_flush_plug(tsk
))
3395 blk_schedule_flush_plug(tsk
);
3398 asmlinkage __visible
void __sched
schedule(void)
3400 struct task_struct
*tsk
= current
;
3402 sched_submit_work(tsk
);
3406 sched_preempt_enable_no_resched();
3407 } while (need_resched());
3409 EXPORT_SYMBOL(schedule
);
3411 #ifdef CONFIG_CONTEXT_TRACKING
3412 asmlinkage __visible
void __sched
schedule_user(void)
3415 * If we come here after a random call to set_need_resched(),
3416 * or we have been woken up remotely but the IPI has not yet arrived,
3417 * we haven't yet exited the RCU idle mode. Do it here manually until
3418 * we find a better solution.
3420 * NB: There are buggy callers of this function. Ideally we
3421 * should warn if prev_state != CONTEXT_USER, but that will trigger
3422 * too frequently to make sense yet.
3424 enum ctx_state prev_state
= exception_enter();
3426 exception_exit(prev_state
);
3431 * schedule_preempt_disabled - called with preemption disabled
3433 * Returns with preemption disabled. Note: preempt_count must be 1
3435 void __sched
schedule_preempt_disabled(void)
3437 sched_preempt_enable_no_resched();
3442 static void __sched notrace
preempt_schedule_common(void)
3446 * Because the function tracer can trace preempt_count_sub()
3447 * and it also uses preempt_enable/disable_notrace(), if
3448 * NEED_RESCHED is set, the preempt_enable_notrace() called
3449 * by the function tracer will call this function again and
3450 * cause infinite recursion.
3452 * Preemption must be disabled here before the function
3453 * tracer can trace. Break up preempt_disable() into two
3454 * calls. One to disable preemption without fear of being
3455 * traced. The other to still record the preemption latency,
3456 * which can also be traced by the function tracer.
3458 preempt_disable_notrace();
3459 preempt_latency_start(1);
3461 preempt_latency_stop(1);
3462 preempt_enable_no_resched_notrace();
3465 * Check again in case we missed a preemption opportunity
3466 * between schedule and now.
3468 } while (need_resched());
3471 #ifdef CONFIG_PREEMPT
3473 * this is the entry point to schedule() from in-kernel preemption
3474 * off of preempt_enable. Kernel preemptions off return from interrupt
3475 * occur there and call schedule directly.
3477 asmlinkage __visible
void __sched notrace
preempt_schedule(void)
3480 * If there is a non-zero preempt_count or interrupts are disabled,
3481 * we do not want to preempt the current task. Just return..
3483 if (likely(!preemptible()))
3486 preempt_schedule_common();
3488 NOKPROBE_SYMBOL(preempt_schedule
);
3489 EXPORT_SYMBOL(preempt_schedule
);
3492 * preempt_schedule_notrace - preempt_schedule called by tracing
3494 * The tracing infrastructure uses preempt_enable_notrace to prevent
3495 * recursion and tracing preempt enabling caused by the tracing
3496 * infrastructure itself. But as tracing can happen in areas coming
3497 * from userspace or just about to enter userspace, a preempt enable
3498 * can occur before user_exit() is called. This will cause the scheduler
3499 * to be called when the system is still in usermode.
3501 * To prevent this, the preempt_enable_notrace will use this function
3502 * instead of preempt_schedule() to exit user context if needed before
3503 * calling the scheduler.
3505 asmlinkage __visible
void __sched notrace
preempt_schedule_notrace(void)
3507 enum ctx_state prev_ctx
;
3509 if (likely(!preemptible()))
3514 * Because the function tracer can trace preempt_count_sub()
3515 * and it also uses preempt_enable/disable_notrace(), if
3516 * NEED_RESCHED is set, the preempt_enable_notrace() called
3517 * by the function tracer will call this function again and
3518 * cause infinite recursion.
3520 * Preemption must be disabled here before the function
3521 * tracer can trace. Break up preempt_disable() into two
3522 * calls. One to disable preemption without fear of being
3523 * traced. The other to still record the preemption latency,
3524 * which can also be traced by the function tracer.
3526 preempt_disable_notrace();
3527 preempt_latency_start(1);
3529 * Needs preempt disabled in case user_exit() is traced
3530 * and the tracer calls preempt_enable_notrace() causing
3531 * an infinite recursion.
3533 prev_ctx
= exception_enter();
3535 exception_exit(prev_ctx
);
3537 preempt_latency_stop(1);
3538 preempt_enable_no_resched_notrace();
3539 } while (need_resched());
3541 EXPORT_SYMBOL_GPL(preempt_schedule_notrace
);
3543 #endif /* CONFIG_PREEMPT */
3546 * this is the entry point to schedule() from kernel preemption
3547 * off of irq context.
3548 * Note, that this is called and return with irqs disabled. This will
3549 * protect us against recursive calling from irq.
3551 asmlinkage __visible
void __sched
preempt_schedule_irq(void)
3553 enum ctx_state prev_state
;
3555 /* Catch callers which need to be fixed */
3556 BUG_ON(preempt_count() || !irqs_disabled());
3558 prev_state
= exception_enter();
3564 local_irq_disable();
3565 sched_preempt_enable_no_resched();
3566 } while (need_resched());
3568 exception_exit(prev_state
);
3571 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
3574 return try_to_wake_up(curr
->private, mode
, wake_flags
);
3576 EXPORT_SYMBOL(default_wake_function
);
3578 #ifdef CONFIG_RT_MUTEXES
3581 * rt_mutex_setprio - set the current priority of a task
3583 * @prio: prio value (kernel-internal form)
3585 * This function changes the 'effective' priority of a task. It does
3586 * not touch ->normal_prio like __setscheduler().
3588 * Used by the rt_mutex code to implement priority inheritance
3589 * logic. Call site only calls if the priority of the task changed.
3591 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3593 int oldprio
, queued
, running
, queue_flag
= DEQUEUE_SAVE
| DEQUEUE_MOVE
;
3594 const struct sched_class
*prev_class
;
3598 BUG_ON(prio
> MAX_PRIO
);
3600 rq
= __task_rq_lock(p
, &rf
);
3603 * Idle task boosting is a nono in general. There is one
3604 * exception, when PREEMPT_RT and NOHZ is active:
3606 * The idle task calls get_next_timer_interrupt() and holds
3607 * the timer wheel base->lock on the CPU and another CPU wants
3608 * to access the timer (probably to cancel it). We can safely
3609 * ignore the boosting request, as the idle CPU runs this code
3610 * with interrupts disabled and will complete the lock
3611 * protected section without being interrupted. So there is no
3612 * real need to boost.
3614 if (unlikely(p
== rq
->idle
)) {
3615 WARN_ON(p
!= rq
->curr
);
3616 WARN_ON(p
->pi_blocked_on
);
3620 trace_sched_pi_setprio(p
, prio
);
3623 if (oldprio
== prio
)
3624 queue_flag
&= ~DEQUEUE_MOVE
;
3626 prev_class
= p
->sched_class
;
3627 queued
= task_on_rq_queued(p
);
3628 running
= task_current(rq
, p
);
3630 dequeue_task(rq
, p
, queue_flag
);
3632 put_prev_task(rq
, p
);
3635 * Boosting condition are:
3636 * 1. -rt task is running and holds mutex A
3637 * --> -dl task blocks on mutex A
3639 * 2. -dl task is running and holds mutex A
3640 * --> -dl task blocks on mutex A and could preempt the
3643 if (dl_prio(prio
)) {
3644 struct task_struct
*pi_task
= rt_mutex_get_top_task(p
);
3645 if (!dl_prio(p
->normal_prio
) ||
3646 (pi_task
&& dl_entity_preempt(&pi_task
->dl
, &p
->dl
))) {
3647 p
->dl
.dl_boosted
= 1;
3648 queue_flag
|= ENQUEUE_REPLENISH
;
3650 p
->dl
.dl_boosted
= 0;
3651 p
->sched_class
= &dl_sched_class
;
3652 } else if (rt_prio(prio
)) {
3653 if (dl_prio(oldprio
))
3654 p
->dl
.dl_boosted
= 0;
3656 queue_flag
|= ENQUEUE_HEAD
;
3657 p
->sched_class
= &rt_sched_class
;
3659 if (dl_prio(oldprio
))
3660 p
->dl
.dl_boosted
= 0;
3661 if (rt_prio(oldprio
))
3663 p
->sched_class
= &fair_sched_class
;
3669 p
->sched_class
->set_curr_task(rq
);
3671 enqueue_task(rq
, p
, queue_flag
);
3673 check_class_changed(rq
, p
, prev_class
, oldprio
);
3675 preempt_disable(); /* avoid rq from going away on us */
3676 __task_rq_unlock(rq
, &rf
);
3678 balance_callback(rq
);
3683 void set_user_nice(struct task_struct
*p
, long nice
)
3685 int old_prio
, delta
, queued
;
3689 if (task_nice(p
) == nice
|| nice
< MIN_NICE
|| nice
> MAX_NICE
)
3692 * We have to be careful, if called from sys_setpriority(),
3693 * the task might be in the middle of scheduling on another CPU.
3695 rq
= task_rq_lock(p
, &rf
);
3697 * The RT priorities are set via sched_setscheduler(), but we still
3698 * allow the 'normal' nice value to be set - but as expected
3699 * it wont have any effect on scheduling until the task is
3700 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3702 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
3703 p
->static_prio
= NICE_TO_PRIO(nice
);
3706 queued
= task_on_rq_queued(p
);
3708 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
3710 p
->static_prio
= NICE_TO_PRIO(nice
);
3713 p
->prio
= effective_prio(p
);
3714 delta
= p
->prio
- old_prio
;
3717 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
3719 * If the task increased its priority or is running and
3720 * lowered its priority, then reschedule its CPU:
3722 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3726 task_rq_unlock(rq
, p
, &rf
);
3728 EXPORT_SYMBOL(set_user_nice
);
3731 * can_nice - check if a task can reduce its nice value
3735 int can_nice(const struct task_struct
*p
, const int nice
)
3737 /* convert nice value [19,-20] to rlimit style value [1,40] */
3738 int nice_rlim
= nice_to_rlimit(nice
);
3740 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3741 capable(CAP_SYS_NICE
));
3744 #ifdef __ARCH_WANT_SYS_NICE
3747 * sys_nice - change the priority of the current process.
3748 * @increment: priority increment
3750 * sys_setpriority is a more generic, but much slower function that
3751 * does similar things.
3753 SYSCALL_DEFINE1(nice
, int, increment
)
3758 * Setpriority might change our priority at the same moment.
3759 * We don't have to worry. Conceptually one call occurs first
3760 * and we have a single winner.
3762 increment
= clamp(increment
, -NICE_WIDTH
, NICE_WIDTH
);
3763 nice
= task_nice(current
) + increment
;
3765 nice
= clamp_val(nice
, MIN_NICE
, MAX_NICE
);
3766 if (increment
< 0 && !can_nice(current
, nice
))
3769 retval
= security_task_setnice(current
, nice
);
3773 set_user_nice(current
, nice
);
3780 * task_prio - return the priority value of a given task.
3781 * @p: the task in question.
3783 * Return: The priority value as seen by users in /proc.
3784 * RT tasks are offset by -200. Normal tasks are centered
3785 * around 0, value goes from -16 to +15.
3787 int task_prio(const struct task_struct
*p
)
3789 return p
->prio
- MAX_RT_PRIO
;
3793 * idle_cpu - is a given cpu idle currently?
3794 * @cpu: the processor in question.
3796 * Return: 1 if the CPU is currently idle. 0 otherwise.
3798 int idle_cpu(int cpu
)
3800 struct rq
*rq
= cpu_rq(cpu
);
3802 if (rq
->curr
!= rq
->idle
)
3809 if (!llist_empty(&rq
->wake_list
))
3817 * idle_task - return the idle task for a given cpu.
3818 * @cpu: the processor in question.
3820 * Return: The idle task for the cpu @cpu.
3822 struct task_struct
*idle_task(int cpu
)
3824 return cpu_rq(cpu
)->idle
;
3828 * find_process_by_pid - find a process with a matching PID value.
3829 * @pid: the pid in question.
3831 * The task of @pid, if found. %NULL otherwise.
3833 static struct task_struct
*find_process_by_pid(pid_t pid
)
3835 return pid
? find_task_by_vpid(pid
) : current
;
3839 * This function initializes the sched_dl_entity of a newly becoming
3840 * SCHED_DEADLINE task.
3842 * Only the static values are considered here, the actual runtime and the
3843 * absolute deadline will be properly calculated when the task is enqueued
3844 * for the first time with its new policy.
3847 __setparam_dl(struct task_struct
*p
, const struct sched_attr
*attr
)
3849 struct sched_dl_entity
*dl_se
= &p
->dl
;
3851 dl_se
->dl_runtime
= attr
->sched_runtime
;
3852 dl_se
->dl_deadline
= attr
->sched_deadline
;
3853 dl_se
->dl_period
= attr
->sched_period
?: dl_se
->dl_deadline
;
3854 dl_se
->flags
= attr
->sched_flags
;
3855 dl_se
->dl_bw
= to_ratio(dl_se
->dl_period
, dl_se
->dl_runtime
);
3858 * Changing the parameters of a task is 'tricky' and we're not doing
3859 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3861 * What we SHOULD do is delay the bandwidth release until the 0-lag
3862 * point. This would include retaining the task_struct until that time
3863 * and change dl_overflow() to not immediately decrement the current
3866 * Instead we retain the current runtime/deadline and let the new
3867 * parameters take effect after the current reservation period lapses.
3868 * This is safe (albeit pessimistic) because the 0-lag point is always
3869 * before the current scheduling deadline.
3871 * We can still have temporary overloads because we do not delay the
3872 * change in bandwidth until that time; so admission control is
3873 * not on the safe side. It does however guarantee tasks will never
3874 * consume more than promised.
3879 * sched_setparam() passes in -1 for its policy, to let the functions
3880 * it calls know not to change it.
3882 #define SETPARAM_POLICY -1
3884 static void __setscheduler_params(struct task_struct
*p
,
3885 const struct sched_attr
*attr
)
3887 int policy
= attr
->sched_policy
;
3889 if (policy
== SETPARAM_POLICY
)
3894 if (dl_policy(policy
))
3895 __setparam_dl(p
, attr
);
3896 else if (fair_policy(policy
))
3897 p
->static_prio
= NICE_TO_PRIO(attr
->sched_nice
);
3900 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3901 * !rt_policy. Always setting this ensures that things like
3902 * getparam()/getattr() don't report silly values for !rt tasks.
3904 p
->rt_priority
= attr
->sched_priority
;
3905 p
->normal_prio
= normal_prio(p
);
3909 /* Actually do priority change: must hold pi & rq lock. */
3910 static void __setscheduler(struct rq
*rq
, struct task_struct
*p
,
3911 const struct sched_attr
*attr
, bool keep_boost
)
3913 __setscheduler_params(p
, attr
);
3916 * Keep a potential priority boosting if called from
3917 * sched_setscheduler().
3920 p
->prio
= rt_mutex_get_effective_prio(p
, normal_prio(p
));
3922 p
->prio
= normal_prio(p
);
3924 if (dl_prio(p
->prio
))
3925 p
->sched_class
= &dl_sched_class
;
3926 else if (rt_prio(p
->prio
))
3927 p
->sched_class
= &rt_sched_class
;
3929 p
->sched_class
= &fair_sched_class
;
3933 __getparam_dl(struct task_struct
*p
, struct sched_attr
*attr
)
3935 struct sched_dl_entity
*dl_se
= &p
->dl
;
3937 attr
->sched_priority
= p
->rt_priority
;
3938 attr
->sched_runtime
= dl_se
->dl_runtime
;
3939 attr
->sched_deadline
= dl_se
->dl_deadline
;
3940 attr
->sched_period
= dl_se
->dl_period
;
3941 attr
->sched_flags
= dl_se
->flags
;
3945 * This function validates the new parameters of a -deadline task.
3946 * We ask for the deadline not being zero, and greater or equal
3947 * than the runtime, as well as the period of being zero or
3948 * greater than deadline. Furthermore, we have to be sure that
3949 * user parameters are above the internal resolution of 1us (we
3950 * check sched_runtime only since it is always the smaller one) and
3951 * below 2^63 ns (we have to check both sched_deadline and
3952 * sched_period, as the latter can be zero).
3955 __checkparam_dl(const struct sched_attr
*attr
)
3958 if (attr
->sched_deadline
== 0)
3962 * Since we truncate DL_SCALE bits, make sure we're at least
3965 if (attr
->sched_runtime
< (1ULL << DL_SCALE
))
3969 * Since we use the MSB for wrap-around and sign issues, make
3970 * sure it's not set (mind that period can be equal to zero).
3972 if (attr
->sched_deadline
& (1ULL << 63) ||
3973 attr
->sched_period
& (1ULL << 63))
3976 /* runtime <= deadline <= period (if period != 0) */
3977 if ((attr
->sched_period
!= 0 &&
3978 attr
->sched_period
< attr
->sched_deadline
) ||
3979 attr
->sched_deadline
< attr
->sched_runtime
)
3986 * check the target process has a UID that matches the current process's
3988 static bool check_same_owner(struct task_struct
*p
)
3990 const struct cred
*cred
= current_cred(), *pcred
;
3994 pcred
= __task_cred(p
);
3995 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3996 uid_eq(cred
->euid
, pcred
->uid
));
4001 static bool dl_param_changed(struct task_struct
*p
,
4002 const struct sched_attr
*attr
)
4004 struct sched_dl_entity
*dl_se
= &p
->dl
;
4006 if (dl_se
->dl_runtime
!= attr
->sched_runtime
||
4007 dl_se
->dl_deadline
!= attr
->sched_deadline
||
4008 dl_se
->dl_period
!= attr
->sched_period
||
4009 dl_se
->flags
!= attr
->sched_flags
)
4015 static int __sched_setscheduler(struct task_struct
*p
,
4016 const struct sched_attr
*attr
,
4019 int newprio
= dl_policy(attr
->sched_policy
) ? MAX_DL_PRIO
- 1 :
4020 MAX_RT_PRIO
- 1 - attr
->sched_priority
;
4021 int retval
, oldprio
, oldpolicy
= -1, queued
, running
;
4022 int new_effective_prio
, policy
= attr
->sched_policy
;
4023 const struct sched_class
*prev_class
;
4026 int queue_flags
= DEQUEUE_SAVE
| DEQUEUE_MOVE
;
4029 /* may grab non-irq protected spin_locks */
4030 BUG_ON(in_interrupt());
4032 /* double check policy once rq lock held */
4034 reset_on_fork
= p
->sched_reset_on_fork
;
4035 policy
= oldpolicy
= p
->policy
;
4037 reset_on_fork
= !!(attr
->sched_flags
& SCHED_FLAG_RESET_ON_FORK
);
4039 if (!valid_policy(policy
))
4043 if (attr
->sched_flags
& ~(SCHED_FLAG_RESET_ON_FORK
))
4047 * Valid priorities for SCHED_FIFO and SCHED_RR are
4048 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4049 * SCHED_BATCH and SCHED_IDLE is 0.
4051 if ((p
->mm
&& attr
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4052 (!p
->mm
&& attr
->sched_priority
> MAX_RT_PRIO
-1))
4054 if ((dl_policy(policy
) && !__checkparam_dl(attr
)) ||
4055 (rt_policy(policy
) != (attr
->sched_priority
!= 0)))
4059 * Allow unprivileged RT tasks to decrease priority:
4061 if (user
&& !capable(CAP_SYS_NICE
)) {
4062 if (fair_policy(policy
)) {
4063 if (attr
->sched_nice
< task_nice(p
) &&
4064 !can_nice(p
, attr
->sched_nice
))
4068 if (rt_policy(policy
)) {
4069 unsigned long rlim_rtprio
=
4070 task_rlimit(p
, RLIMIT_RTPRIO
);
4072 /* can't set/change the rt policy */
4073 if (policy
!= p
->policy
&& !rlim_rtprio
)
4076 /* can't increase priority */
4077 if (attr
->sched_priority
> p
->rt_priority
&&
4078 attr
->sched_priority
> rlim_rtprio
)
4083 * Can't set/change SCHED_DEADLINE policy at all for now
4084 * (safest behavior); in the future we would like to allow
4085 * unprivileged DL tasks to increase their relative deadline
4086 * or reduce their runtime (both ways reducing utilization)
4088 if (dl_policy(policy
))
4092 * Treat SCHED_IDLE as nice 20. Only allow a switch to
4093 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
4095 if (idle_policy(p
->policy
) && !idle_policy(policy
)) {
4096 if (!can_nice(p
, task_nice(p
)))
4100 /* can't change other user's priorities */
4101 if (!check_same_owner(p
))
4104 /* Normal users shall not reset the sched_reset_on_fork flag */
4105 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
4110 retval
= security_task_setscheduler(p
);
4116 * make sure no PI-waiters arrive (or leave) while we are
4117 * changing the priority of the task:
4119 * To be able to change p->policy safely, the appropriate
4120 * runqueue lock must be held.
4122 rq
= task_rq_lock(p
, &rf
);
4125 * Changing the policy of the stop threads its a very bad idea
4127 if (p
== rq
->stop
) {
4128 task_rq_unlock(rq
, p
, &rf
);
4133 * If not changing anything there's no need to proceed further,
4134 * but store a possible modification of reset_on_fork.
4136 if (unlikely(policy
== p
->policy
)) {
4137 if (fair_policy(policy
) && attr
->sched_nice
!= task_nice(p
))
4139 if (rt_policy(policy
) && attr
->sched_priority
!= p
->rt_priority
)
4141 if (dl_policy(policy
) && dl_param_changed(p
, attr
))
4144 p
->sched_reset_on_fork
= reset_on_fork
;
4145 task_rq_unlock(rq
, p
, &rf
);
4151 #ifdef CONFIG_RT_GROUP_SCHED
4153 * Do not allow realtime tasks into groups that have no runtime
4156 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
4157 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
4158 !task_group_is_autogroup(task_group(p
))) {
4159 task_rq_unlock(rq
, p
, &rf
);
4164 if (dl_bandwidth_enabled() && dl_policy(policy
)) {
4165 cpumask_t
*span
= rq
->rd
->span
;
4168 * Don't allow tasks with an affinity mask smaller than
4169 * the entire root_domain to become SCHED_DEADLINE. We
4170 * will also fail if there's no bandwidth available.
4172 if (!cpumask_subset(span
, &p
->cpus_allowed
) ||
4173 rq
->rd
->dl_bw
.bw
== 0) {
4174 task_rq_unlock(rq
, p
, &rf
);
4181 /* recheck policy now with rq lock held */
4182 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4183 policy
= oldpolicy
= -1;
4184 task_rq_unlock(rq
, p
, &rf
);
4189 * If setscheduling to SCHED_DEADLINE (or changing the parameters
4190 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4193 if ((dl_policy(policy
) || dl_task(p
)) && dl_overflow(p
, policy
, attr
)) {
4194 task_rq_unlock(rq
, p
, &rf
);
4198 p
->sched_reset_on_fork
= reset_on_fork
;
4203 * Take priority boosted tasks into account. If the new
4204 * effective priority is unchanged, we just store the new
4205 * normal parameters and do not touch the scheduler class and
4206 * the runqueue. This will be done when the task deboost
4209 new_effective_prio
= rt_mutex_get_effective_prio(p
, newprio
);
4210 if (new_effective_prio
== oldprio
)
4211 queue_flags
&= ~DEQUEUE_MOVE
;
4214 queued
= task_on_rq_queued(p
);
4215 running
= task_current(rq
, p
);
4217 dequeue_task(rq
, p
, queue_flags
);
4219 put_prev_task(rq
, p
);
4221 prev_class
= p
->sched_class
;
4222 __setscheduler(rq
, p
, attr
, pi
);
4225 p
->sched_class
->set_curr_task(rq
);
4228 * We enqueue to tail when the priority of a task is
4229 * increased (user space view).
4231 if (oldprio
< p
->prio
)
4232 queue_flags
|= ENQUEUE_HEAD
;
4234 enqueue_task(rq
, p
, queue_flags
);
4237 check_class_changed(rq
, p
, prev_class
, oldprio
);
4238 preempt_disable(); /* avoid rq from going away on us */
4239 task_rq_unlock(rq
, p
, &rf
);
4242 rt_mutex_adjust_pi(p
);
4245 * Run balance callbacks after we've adjusted the PI chain.
4247 balance_callback(rq
);
4253 static int _sched_setscheduler(struct task_struct
*p
, int policy
,
4254 const struct sched_param
*param
, bool check
)
4256 struct sched_attr attr
= {
4257 .sched_policy
= policy
,
4258 .sched_priority
= param
->sched_priority
,
4259 .sched_nice
= PRIO_TO_NICE(p
->static_prio
),
4262 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4263 if ((policy
!= SETPARAM_POLICY
) && (policy
& SCHED_RESET_ON_FORK
)) {
4264 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
4265 policy
&= ~SCHED_RESET_ON_FORK
;
4266 attr
.sched_policy
= policy
;
4269 return __sched_setscheduler(p
, &attr
, check
, true);
4272 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4273 * @p: the task in question.
4274 * @policy: new policy.
4275 * @param: structure containing the new RT priority.
4277 * Return: 0 on success. An error code otherwise.
4279 * NOTE that the task may be already dead.
4281 int sched_setscheduler(struct task_struct
*p
, int policy
,
4282 const struct sched_param
*param
)
4284 return _sched_setscheduler(p
, policy
, param
, true);
4286 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4288 int sched_setattr(struct task_struct
*p
, const struct sched_attr
*attr
)
4290 return __sched_setscheduler(p
, attr
, true, true);
4292 EXPORT_SYMBOL_GPL(sched_setattr
);
4295 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4296 * @p: the task in question.
4297 * @policy: new policy.
4298 * @param: structure containing the new RT priority.
4300 * Just like sched_setscheduler, only don't bother checking if the
4301 * current context has permission. For example, this is needed in
4302 * stop_machine(): we create temporary high priority worker threads,
4303 * but our caller might not have that capability.
4305 * Return: 0 on success. An error code otherwise.
4307 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
4308 const struct sched_param
*param
)
4310 return _sched_setscheduler(p
, policy
, param
, false);
4312 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck
);
4315 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4317 struct sched_param lparam
;
4318 struct task_struct
*p
;
4321 if (!param
|| pid
< 0)
4323 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4328 p
= find_process_by_pid(pid
);
4330 retval
= sched_setscheduler(p
, policy
, &lparam
);
4337 * Mimics kernel/events/core.c perf_copy_attr().
4339 static int sched_copy_attr(struct sched_attr __user
*uattr
,
4340 struct sched_attr
*attr
)
4345 if (!access_ok(VERIFY_WRITE
, uattr
, SCHED_ATTR_SIZE_VER0
))
4349 * zero the full structure, so that a short copy will be nice.
4351 memset(attr
, 0, sizeof(*attr
));
4353 ret
= get_user(size
, &uattr
->size
);
4357 if (size
> PAGE_SIZE
) /* silly large */
4360 if (!size
) /* abi compat */
4361 size
= SCHED_ATTR_SIZE_VER0
;
4363 if (size
< SCHED_ATTR_SIZE_VER0
)
4367 * If we're handed a bigger struct than we know of,
4368 * ensure all the unknown bits are 0 - i.e. new
4369 * user-space does not rely on any kernel feature
4370 * extensions we dont know about yet.
4372 if (size
> sizeof(*attr
)) {
4373 unsigned char __user
*addr
;
4374 unsigned char __user
*end
;
4377 addr
= (void __user
*)uattr
+ sizeof(*attr
);
4378 end
= (void __user
*)uattr
+ size
;
4380 for (; addr
< end
; addr
++) {
4381 ret
= get_user(val
, addr
);
4387 size
= sizeof(*attr
);
4390 ret
= copy_from_user(attr
, uattr
, size
);
4395 * XXX: do we want to be lenient like existing syscalls; or do we want
4396 * to be strict and return an error on out-of-bounds values?
4398 attr
->sched_nice
= clamp(attr
->sched_nice
, MIN_NICE
, MAX_NICE
);
4403 put_user(sizeof(*attr
), &uattr
->size
);
4408 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4409 * @pid: the pid in question.
4410 * @policy: new policy.
4411 * @param: structure containing the new RT priority.
4413 * Return: 0 on success. An error code otherwise.
4415 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
4416 struct sched_param __user
*, param
)
4418 /* negative values for policy are not valid */
4422 return do_sched_setscheduler(pid
, policy
, param
);
4426 * sys_sched_setparam - set/change the RT priority of a thread
4427 * @pid: the pid in question.
4428 * @param: structure containing the new RT priority.
4430 * Return: 0 on success. An error code otherwise.
4432 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4434 return do_sched_setscheduler(pid
, SETPARAM_POLICY
, param
);
4438 * sys_sched_setattr - same as above, but with extended sched_attr
4439 * @pid: the pid in question.
4440 * @uattr: structure containing the extended parameters.
4441 * @flags: for future extension.
4443 SYSCALL_DEFINE3(sched_setattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
4444 unsigned int, flags
)
4446 struct sched_attr attr
;
4447 struct task_struct
*p
;
4450 if (!uattr
|| pid
< 0 || flags
)
4453 retval
= sched_copy_attr(uattr
, &attr
);
4457 if ((int)attr
.sched_policy
< 0)
4462 p
= find_process_by_pid(pid
);
4464 retval
= sched_setattr(p
, &attr
);
4471 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4472 * @pid: the pid in question.
4474 * Return: On success, the policy of the thread. Otherwise, a negative error
4477 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
4479 struct task_struct
*p
;
4487 p
= find_process_by_pid(pid
);
4489 retval
= security_task_getscheduler(p
);
4492 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
4499 * sys_sched_getparam - get the RT priority of a thread
4500 * @pid: the pid in question.
4501 * @param: structure containing the RT priority.
4503 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4506 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4508 struct sched_param lp
= { .sched_priority
= 0 };
4509 struct task_struct
*p
;
4512 if (!param
|| pid
< 0)
4516 p
= find_process_by_pid(pid
);
4521 retval
= security_task_getscheduler(p
);
4525 if (task_has_rt_policy(p
))
4526 lp
.sched_priority
= p
->rt_priority
;
4530 * This one might sleep, we cannot do it with a spinlock held ...
4532 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4541 static int sched_read_attr(struct sched_attr __user
*uattr
,
4542 struct sched_attr
*attr
,
4547 if (!access_ok(VERIFY_WRITE
, uattr
, usize
))
4551 * If we're handed a smaller struct than we know of,
4552 * ensure all the unknown bits are 0 - i.e. old
4553 * user-space does not get uncomplete information.
4555 if (usize
< sizeof(*attr
)) {
4556 unsigned char *addr
;
4559 addr
= (void *)attr
+ usize
;
4560 end
= (void *)attr
+ sizeof(*attr
);
4562 for (; addr
< end
; addr
++) {
4570 ret
= copy_to_user(uattr
, attr
, attr
->size
);
4578 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4579 * @pid: the pid in question.
4580 * @uattr: structure containing the extended parameters.
4581 * @size: sizeof(attr) for fwd/bwd comp.
4582 * @flags: for future extension.
4584 SYSCALL_DEFINE4(sched_getattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
4585 unsigned int, size
, unsigned int, flags
)
4587 struct sched_attr attr
= {
4588 .size
= sizeof(struct sched_attr
),
4590 struct task_struct
*p
;
4593 if (!uattr
|| pid
< 0 || size
> PAGE_SIZE
||
4594 size
< SCHED_ATTR_SIZE_VER0
|| flags
)
4598 p
= find_process_by_pid(pid
);
4603 retval
= security_task_getscheduler(p
);
4607 attr
.sched_policy
= p
->policy
;
4608 if (p
->sched_reset_on_fork
)
4609 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
4610 if (task_has_dl_policy(p
))
4611 __getparam_dl(p
, &attr
);
4612 else if (task_has_rt_policy(p
))
4613 attr
.sched_priority
= p
->rt_priority
;
4615 attr
.sched_nice
= task_nice(p
);
4619 retval
= sched_read_attr(uattr
, &attr
, size
);
4627 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
4629 cpumask_var_t cpus_allowed
, new_mask
;
4630 struct task_struct
*p
;
4635 p
= find_process_by_pid(pid
);
4641 /* Prevent p going away */
4645 if (p
->flags
& PF_NO_SETAFFINITY
) {
4649 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4653 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4655 goto out_free_cpus_allowed
;
4658 if (!check_same_owner(p
)) {
4660 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4662 goto out_free_new_mask
;
4667 retval
= security_task_setscheduler(p
);
4669 goto out_free_new_mask
;
4672 cpuset_cpus_allowed(p
, cpus_allowed
);
4673 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4676 * Since bandwidth control happens on root_domain basis,
4677 * if admission test is enabled, we only admit -deadline
4678 * tasks allowed to run on all the CPUs in the task's
4682 if (task_has_dl_policy(p
) && dl_bandwidth_enabled()) {
4684 if (!cpumask_subset(task_rq(p
)->rd
->span
, new_mask
)) {
4687 goto out_free_new_mask
;
4693 retval
= __set_cpus_allowed_ptr(p
, new_mask
, true);
4696 cpuset_cpus_allowed(p
, cpus_allowed
);
4697 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4699 * We must have raced with a concurrent cpuset
4700 * update. Just reset the cpus_allowed to the
4701 * cpuset's cpus_allowed
4703 cpumask_copy(new_mask
, cpus_allowed
);
4708 free_cpumask_var(new_mask
);
4709 out_free_cpus_allowed
:
4710 free_cpumask_var(cpus_allowed
);
4716 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4717 struct cpumask
*new_mask
)
4719 if (len
< cpumask_size())
4720 cpumask_clear(new_mask
);
4721 else if (len
> cpumask_size())
4722 len
= cpumask_size();
4724 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4728 * sys_sched_setaffinity - set the cpu affinity of a process
4729 * @pid: pid of the process
4730 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4731 * @user_mask_ptr: user-space pointer to the new cpu mask
4733 * Return: 0 on success. An error code otherwise.
4735 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4736 unsigned long __user
*, user_mask_ptr
)
4738 cpumask_var_t new_mask
;
4741 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4744 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4746 retval
= sched_setaffinity(pid
, new_mask
);
4747 free_cpumask_var(new_mask
);
4751 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4753 struct task_struct
*p
;
4754 unsigned long flags
;
4760 p
= find_process_by_pid(pid
);
4764 retval
= security_task_getscheduler(p
);
4768 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4769 cpumask_and(mask
, &p
->cpus_allowed
, cpu_active_mask
);
4770 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4779 * sys_sched_getaffinity - get the cpu affinity of a process
4780 * @pid: pid of the process
4781 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4782 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4784 * Return: size of CPU mask copied to user_mask_ptr on success. An
4785 * error code otherwise.
4787 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4788 unsigned long __user
*, user_mask_ptr
)
4793 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4795 if (len
& (sizeof(unsigned long)-1))
4798 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4801 ret
= sched_getaffinity(pid
, mask
);
4803 size_t retlen
= min_t(size_t, len
, cpumask_size());
4805 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4810 free_cpumask_var(mask
);
4816 * sys_sched_yield - yield the current processor to other threads.
4818 * This function yields the current CPU to other tasks. If there are no
4819 * other threads running on this CPU then this function will return.
4823 SYSCALL_DEFINE0(sched_yield
)
4825 struct rq
*rq
= this_rq_lock();
4827 schedstat_inc(rq
, yld_count
);
4828 current
->sched_class
->yield_task(rq
);
4831 * Since we are going to call schedule() anyway, there's
4832 * no need to preempt or enable interrupts:
4834 __release(rq
->lock
);
4835 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4836 do_raw_spin_unlock(&rq
->lock
);
4837 sched_preempt_enable_no_resched();
4844 int __sched
_cond_resched(void)
4846 if (should_resched(0)) {
4847 preempt_schedule_common();
4852 EXPORT_SYMBOL(_cond_resched
);
4855 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4856 * call schedule, and on return reacquire the lock.
4858 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4859 * operations here to prevent schedule() from being called twice (once via
4860 * spin_unlock(), once by hand).
4862 int __cond_resched_lock(spinlock_t
*lock
)
4864 int resched
= should_resched(PREEMPT_LOCK_OFFSET
);
4867 lockdep_assert_held(lock
);
4869 if (spin_needbreak(lock
) || resched
) {
4872 preempt_schedule_common();
4880 EXPORT_SYMBOL(__cond_resched_lock
);
4882 int __sched
__cond_resched_softirq(void)
4884 BUG_ON(!in_softirq());
4886 if (should_resched(SOFTIRQ_DISABLE_OFFSET
)) {
4888 preempt_schedule_common();
4894 EXPORT_SYMBOL(__cond_resched_softirq
);
4897 * yield - yield the current processor to other threads.
4899 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4901 * The scheduler is at all times free to pick the calling task as the most
4902 * eligible task to run, if removing the yield() call from your code breaks
4903 * it, its already broken.
4905 * Typical broken usage is:
4910 * where one assumes that yield() will let 'the other' process run that will
4911 * make event true. If the current task is a SCHED_FIFO task that will never
4912 * happen. Never use yield() as a progress guarantee!!
4914 * If you want to use yield() to wait for something, use wait_event().
4915 * If you want to use yield() to be 'nice' for others, use cond_resched().
4916 * If you still want to use yield(), do not!
4918 void __sched
yield(void)
4920 set_current_state(TASK_RUNNING
);
4923 EXPORT_SYMBOL(yield
);
4926 * yield_to - yield the current processor to another thread in
4927 * your thread group, or accelerate that thread toward the
4928 * processor it's on.
4930 * @preempt: whether task preemption is allowed or not
4932 * It's the caller's job to ensure that the target task struct
4933 * can't go away on us before we can do any checks.
4936 * true (>0) if we indeed boosted the target task.
4937 * false (0) if we failed to boost the target.
4938 * -ESRCH if there's no task to yield to.
4940 int __sched
yield_to(struct task_struct
*p
, bool preempt
)
4942 struct task_struct
*curr
= current
;
4943 struct rq
*rq
, *p_rq
;
4944 unsigned long flags
;
4947 local_irq_save(flags
);
4953 * If we're the only runnable task on the rq and target rq also
4954 * has only one task, there's absolutely no point in yielding.
4956 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4961 double_rq_lock(rq
, p_rq
);
4962 if (task_rq(p
) != p_rq
) {
4963 double_rq_unlock(rq
, p_rq
);
4967 if (!curr
->sched_class
->yield_to_task
)
4970 if (curr
->sched_class
!= p
->sched_class
)
4973 if (task_running(p_rq
, p
) || p
->state
)
4976 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4978 schedstat_inc(rq
, yld_count
);
4980 * Make p's CPU reschedule; pick_next_entity takes care of
4983 if (preempt
&& rq
!= p_rq
)
4988 double_rq_unlock(rq
, p_rq
);
4990 local_irq_restore(flags
);
4997 EXPORT_SYMBOL_GPL(yield_to
);
5000 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5001 * that process accounting knows that this is a task in IO wait state.
5003 long __sched
io_schedule_timeout(long timeout
)
5005 int old_iowait
= current
->in_iowait
;
5009 current
->in_iowait
= 1;
5010 blk_schedule_flush_plug(current
);
5012 delayacct_blkio_start();
5014 atomic_inc(&rq
->nr_iowait
);
5015 ret
= schedule_timeout(timeout
);
5016 current
->in_iowait
= old_iowait
;
5017 atomic_dec(&rq
->nr_iowait
);
5018 delayacct_blkio_end();
5022 EXPORT_SYMBOL(io_schedule_timeout
);
5025 * sys_sched_get_priority_max - return maximum RT priority.
5026 * @policy: scheduling class.
5028 * Return: On success, this syscall returns the maximum
5029 * rt_priority that can be used by a given scheduling class.
5030 * On failure, a negative error code is returned.
5032 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
5039 ret
= MAX_USER_RT_PRIO
-1;
5041 case SCHED_DEADLINE
:
5052 * sys_sched_get_priority_min - return minimum RT priority.
5053 * @policy: scheduling class.
5055 * Return: On success, this syscall returns the minimum
5056 * rt_priority that can be used by a given scheduling class.
5057 * On failure, a negative error code is returned.
5059 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
5068 case SCHED_DEADLINE
:
5078 * sys_sched_rr_get_interval - return the default timeslice of a process.
5079 * @pid: pid of the process.
5080 * @interval: userspace pointer to the timeslice value.
5082 * this syscall writes the default timeslice value of a given process
5083 * into the user-space timespec buffer. A value of '0' means infinity.
5085 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
5088 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
5089 struct timespec __user
*, interval
)
5091 struct task_struct
*p
;
5092 unsigned int time_slice
;
5103 p
= find_process_by_pid(pid
);
5107 retval
= security_task_getscheduler(p
);
5111 rq
= task_rq_lock(p
, &rf
);
5113 if (p
->sched_class
->get_rr_interval
)
5114 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
5115 task_rq_unlock(rq
, p
, &rf
);
5118 jiffies_to_timespec(time_slice
, &t
);
5119 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
5127 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
5129 void sched_show_task(struct task_struct
*p
)
5131 unsigned long free
= 0;
5133 unsigned long state
= p
->state
;
5136 state
= __ffs(state
) + 1;
5137 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
5138 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
5139 #if BITS_PER_LONG == 32
5140 if (state
== TASK_RUNNING
)
5141 printk(KERN_CONT
" running ");
5143 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
5145 if (state
== TASK_RUNNING
)
5146 printk(KERN_CONT
" running task ");
5148 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
5150 #ifdef CONFIG_DEBUG_STACK_USAGE
5151 free
= stack_not_used(p
);
5156 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
5158 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
5159 task_pid_nr(p
), ppid
,
5160 (unsigned long)task_thread_info(p
)->flags
);
5162 print_worker_info(KERN_INFO
, p
);
5163 show_stack(p
, NULL
);
5166 void show_state_filter(unsigned long state_filter
)
5168 struct task_struct
*g
, *p
;
5170 #if BITS_PER_LONG == 32
5172 " task PC stack pid father\n");
5175 " task PC stack pid father\n");
5178 for_each_process_thread(g
, p
) {
5180 * reset the NMI-timeout, listing all files on a slow
5181 * console might take a lot of time:
5182 * Also, reset softlockup watchdogs on all CPUs, because
5183 * another CPU might be blocked waiting for us to process
5186 touch_nmi_watchdog();
5187 touch_all_softlockup_watchdogs();
5188 if (!state_filter
|| (p
->state
& state_filter
))
5192 #ifdef CONFIG_SCHED_DEBUG
5194 sysrq_sched_debug_show();
5198 * Only show locks if all tasks are dumped:
5201 debug_show_all_locks();
5204 void init_idle_bootup_task(struct task_struct
*idle
)
5206 idle
->sched_class
= &idle_sched_class
;
5210 * init_idle - set up an idle thread for a given CPU
5211 * @idle: task in question
5212 * @cpu: cpu the idle task belongs to
5214 * NOTE: this function does not set the idle thread's NEED_RESCHED
5215 * flag, to make booting more robust.
5217 void init_idle(struct task_struct
*idle
, int cpu
)
5219 struct rq
*rq
= cpu_rq(cpu
);
5220 unsigned long flags
;
5222 raw_spin_lock_irqsave(&idle
->pi_lock
, flags
);
5223 raw_spin_lock(&rq
->lock
);
5225 __sched_fork(0, idle
);
5226 idle
->state
= TASK_RUNNING
;
5227 idle
->se
.exec_start
= sched_clock();
5229 kasan_unpoison_task_stack(idle
);
5233 * Its possible that init_idle() gets called multiple times on a task,
5234 * in that case do_set_cpus_allowed() will not do the right thing.
5236 * And since this is boot we can forgo the serialization.
5238 set_cpus_allowed_common(idle
, cpumask_of(cpu
));
5241 * We're having a chicken and egg problem, even though we are
5242 * holding rq->lock, the cpu isn't yet set to this cpu so the
5243 * lockdep check in task_group() will fail.
5245 * Similar case to sched_fork(). / Alternatively we could
5246 * use task_rq_lock() here and obtain the other rq->lock.
5251 __set_task_cpu(idle
, cpu
);
5254 rq
->curr
= rq
->idle
= idle
;
5255 idle
->on_rq
= TASK_ON_RQ_QUEUED
;
5259 raw_spin_unlock(&rq
->lock
);
5260 raw_spin_unlock_irqrestore(&idle
->pi_lock
, flags
);
5262 /* Set the preempt count _outside_ the spinlocks! */
5263 init_idle_preempt_count(idle
, cpu
);
5266 * The idle tasks have their own, simple scheduling class:
5268 idle
->sched_class
= &idle_sched_class
;
5269 ftrace_graph_init_idle_task(idle
, cpu
);
5270 vtime_init_idle(idle
, cpu
);
5272 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
5276 int cpuset_cpumask_can_shrink(const struct cpumask
*cur
,
5277 const struct cpumask
*trial
)
5279 int ret
= 1, trial_cpus
;
5280 struct dl_bw
*cur_dl_b
;
5281 unsigned long flags
;
5283 if (!cpumask_weight(cur
))
5286 rcu_read_lock_sched();
5287 cur_dl_b
= dl_bw_of(cpumask_any(cur
));
5288 trial_cpus
= cpumask_weight(trial
);
5290 raw_spin_lock_irqsave(&cur_dl_b
->lock
, flags
);
5291 if (cur_dl_b
->bw
!= -1 &&
5292 cur_dl_b
->bw
* trial_cpus
< cur_dl_b
->total_bw
)
5294 raw_spin_unlock_irqrestore(&cur_dl_b
->lock
, flags
);
5295 rcu_read_unlock_sched();
5300 int task_can_attach(struct task_struct
*p
,
5301 const struct cpumask
*cs_cpus_allowed
)
5306 * Kthreads which disallow setaffinity shouldn't be moved
5307 * to a new cpuset; we don't want to change their cpu
5308 * affinity and isolating such threads by their set of
5309 * allowed nodes is unnecessary. Thus, cpusets are not
5310 * applicable for such threads. This prevents checking for
5311 * success of set_cpus_allowed_ptr() on all attached tasks
5312 * before cpus_allowed may be changed.
5314 if (p
->flags
& PF_NO_SETAFFINITY
) {
5320 if (dl_task(p
) && !cpumask_intersects(task_rq(p
)->rd
->span
,
5322 unsigned int dest_cpu
= cpumask_any_and(cpu_active_mask
,
5327 unsigned long flags
;
5329 rcu_read_lock_sched();
5330 dl_b
= dl_bw_of(dest_cpu
);
5331 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
5332 cpus
= dl_bw_cpus(dest_cpu
);
5333 overflow
= __dl_overflow(dl_b
, cpus
, 0, p
->dl
.dl_bw
);
5338 * We reserve space for this task in the destination
5339 * root_domain, as we can't fail after this point.
5340 * We will free resources in the source root_domain
5341 * later on (see set_cpus_allowed_dl()).
5343 __dl_add(dl_b
, p
->dl
.dl_bw
);
5345 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
5346 rcu_read_unlock_sched();
5356 static bool sched_smp_initialized __read_mostly
;
5358 #ifdef CONFIG_NUMA_BALANCING
5359 /* Migrate current task p to target_cpu */
5360 int migrate_task_to(struct task_struct
*p
, int target_cpu
)
5362 struct migration_arg arg
= { p
, target_cpu
};
5363 int curr_cpu
= task_cpu(p
);
5365 if (curr_cpu
== target_cpu
)
5368 if (!cpumask_test_cpu(target_cpu
, tsk_cpus_allowed(p
)))
5371 /* TODO: This is not properly updating schedstats */
5373 trace_sched_move_numa(p
, curr_cpu
, target_cpu
);
5374 return stop_one_cpu(curr_cpu
, migration_cpu_stop
, &arg
);
5378 * Requeue a task on a given node and accurately track the number of NUMA
5379 * tasks on the runqueues
5381 void sched_setnuma(struct task_struct
*p
, int nid
)
5383 bool queued
, running
;
5387 rq
= task_rq_lock(p
, &rf
);
5388 queued
= task_on_rq_queued(p
);
5389 running
= task_current(rq
, p
);
5392 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
5394 put_prev_task(rq
, p
);
5396 p
->numa_preferred_nid
= nid
;
5399 p
->sched_class
->set_curr_task(rq
);
5401 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
5402 task_rq_unlock(rq
, p
, &rf
);
5404 #endif /* CONFIG_NUMA_BALANCING */
5406 #ifdef CONFIG_HOTPLUG_CPU
5408 * Ensures that the idle task is using init_mm right before its cpu goes
5411 void idle_task_exit(void)
5413 struct mm_struct
*mm
= current
->active_mm
;
5415 BUG_ON(cpu_online(smp_processor_id()));
5417 if (mm
!= &init_mm
) {
5418 switch_mm_irqs_off(mm
, &init_mm
, current
);
5419 finish_arch_post_lock_switch();
5425 * Since this CPU is going 'away' for a while, fold any nr_active delta
5426 * we might have. Assumes we're called after migrate_tasks() so that the
5427 * nr_active count is stable. We need to take the teardown thread which
5428 * is calling this into account, so we hand in adjust = 1 to the load
5431 * Also see the comment "Global load-average calculations".
5433 static void calc_load_migrate(struct rq
*rq
)
5435 long delta
= calc_load_fold_active(rq
, 1);
5437 atomic_long_add(delta
, &calc_load_tasks
);
5440 static void put_prev_task_fake(struct rq
*rq
, struct task_struct
*prev
)
5444 static const struct sched_class fake_sched_class
= {
5445 .put_prev_task
= put_prev_task_fake
,
5448 static struct task_struct fake_task
= {
5450 * Avoid pull_{rt,dl}_task()
5452 .prio
= MAX_PRIO
+ 1,
5453 .sched_class
= &fake_sched_class
,
5457 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5458 * try_to_wake_up()->select_task_rq().
5460 * Called with rq->lock held even though we'er in stop_machine() and
5461 * there's no concurrency possible, we hold the required locks anyway
5462 * because of lock validation efforts.
5464 static void migrate_tasks(struct rq
*dead_rq
)
5466 struct rq
*rq
= dead_rq
;
5467 struct task_struct
*next
, *stop
= rq
->stop
;
5468 struct pin_cookie cookie
;
5472 * Fudge the rq selection such that the below task selection loop
5473 * doesn't get stuck on the currently eligible stop task.
5475 * We're currently inside stop_machine() and the rq is either stuck
5476 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5477 * either way we should never end up calling schedule() until we're
5483 * put_prev_task() and pick_next_task() sched
5484 * class method both need to have an up-to-date
5485 * value of rq->clock[_task]
5487 update_rq_clock(rq
);
5491 * There's this thread running, bail when that's the only
5494 if (rq
->nr_running
== 1)
5498 * pick_next_task assumes pinned rq->lock.
5500 cookie
= lockdep_pin_lock(&rq
->lock
);
5501 next
= pick_next_task(rq
, &fake_task
, cookie
);
5503 next
->sched_class
->put_prev_task(rq
, next
);
5506 * Rules for changing task_struct::cpus_allowed are holding
5507 * both pi_lock and rq->lock, such that holding either
5508 * stabilizes the mask.
5510 * Drop rq->lock is not quite as disastrous as it usually is
5511 * because !cpu_active at this point, which means load-balance
5512 * will not interfere. Also, stop-machine.
5514 lockdep_unpin_lock(&rq
->lock
, cookie
);
5515 raw_spin_unlock(&rq
->lock
);
5516 raw_spin_lock(&next
->pi_lock
);
5517 raw_spin_lock(&rq
->lock
);
5520 * Since we're inside stop-machine, _nothing_ should have
5521 * changed the task, WARN if weird stuff happened, because in
5522 * that case the above rq->lock drop is a fail too.
5524 if (WARN_ON(task_rq(next
) != rq
|| !task_on_rq_queued(next
))) {
5525 raw_spin_unlock(&next
->pi_lock
);
5529 /* Find suitable destination for @next, with force if needed. */
5530 dest_cpu
= select_fallback_rq(dead_rq
->cpu
, next
);
5532 rq
= __migrate_task(rq
, next
, dest_cpu
);
5533 if (rq
!= dead_rq
) {
5534 raw_spin_unlock(&rq
->lock
);
5536 raw_spin_lock(&rq
->lock
);
5538 raw_spin_unlock(&next
->pi_lock
);
5543 #endif /* CONFIG_HOTPLUG_CPU */
5545 static void set_rq_online(struct rq
*rq
)
5548 const struct sched_class
*class;
5550 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5553 for_each_class(class) {
5554 if (class->rq_online
)
5555 class->rq_online(rq
);
5560 static void set_rq_offline(struct rq
*rq
)
5563 const struct sched_class
*class;
5565 for_each_class(class) {
5566 if (class->rq_offline
)
5567 class->rq_offline(rq
);
5570 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5575 static void set_cpu_rq_start_time(unsigned int cpu
)
5577 struct rq
*rq
= cpu_rq(cpu
);
5579 rq
->age_stamp
= sched_clock_cpu(cpu
);
5582 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5584 #ifdef CONFIG_SCHED_DEBUG
5586 static __read_mostly
int sched_debug_enabled
;
5588 static int __init
sched_debug_setup(char *str
)
5590 sched_debug_enabled
= 1;
5594 early_param("sched_debug", sched_debug_setup
);
5596 static inline bool sched_debug(void)
5598 return sched_debug_enabled
;
5601 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5602 struct cpumask
*groupmask
)
5604 struct sched_group
*group
= sd
->groups
;
5606 cpumask_clear(groupmask
);
5608 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5610 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5611 printk("does not load-balance\n");
5613 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5618 printk(KERN_CONT
"span %*pbl level %s\n",
5619 cpumask_pr_args(sched_domain_span(sd
)), sd
->name
);
5621 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5622 printk(KERN_ERR
"ERROR: domain->span does not contain "
5625 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5626 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5630 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5634 printk(KERN_ERR
"ERROR: group is NULL\n");
5638 if (!cpumask_weight(sched_group_cpus(group
))) {
5639 printk(KERN_CONT
"\n");
5640 printk(KERN_ERR
"ERROR: empty group\n");
5644 if (!(sd
->flags
& SD_OVERLAP
) &&
5645 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5646 printk(KERN_CONT
"\n");
5647 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5651 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5653 printk(KERN_CONT
" %*pbl",
5654 cpumask_pr_args(sched_group_cpus(group
)));
5655 if (group
->sgc
->capacity
!= SCHED_CAPACITY_SCALE
) {
5656 printk(KERN_CONT
" (cpu_capacity = %d)",
5657 group
->sgc
->capacity
);
5660 group
= group
->next
;
5661 } while (group
!= sd
->groups
);
5662 printk(KERN_CONT
"\n");
5664 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5665 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5668 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5669 printk(KERN_ERR
"ERROR: parent span is not a superset "
5670 "of domain->span\n");
5674 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5678 if (!sched_debug_enabled
)
5682 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5686 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5689 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5697 #else /* !CONFIG_SCHED_DEBUG */
5698 # define sched_domain_debug(sd, cpu) do { } while (0)
5699 static inline bool sched_debug(void)
5703 #endif /* CONFIG_SCHED_DEBUG */
5705 static int sd_degenerate(struct sched_domain
*sd
)
5707 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5710 /* Following flags need at least 2 groups */
5711 if (sd
->flags
& (SD_LOAD_BALANCE
|
5712 SD_BALANCE_NEWIDLE
|
5715 SD_SHARE_CPUCAPACITY
|
5716 SD_SHARE_PKG_RESOURCES
|
5717 SD_SHARE_POWERDOMAIN
)) {
5718 if (sd
->groups
!= sd
->groups
->next
)
5722 /* Following flags don't use groups */
5723 if (sd
->flags
& (SD_WAKE_AFFINE
))
5730 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5732 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5734 if (sd_degenerate(parent
))
5737 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5740 /* Flags needing groups don't count if only 1 group in parent */
5741 if (parent
->groups
== parent
->groups
->next
) {
5742 pflags
&= ~(SD_LOAD_BALANCE
|
5743 SD_BALANCE_NEWIDLE
|
5746 SD_SHARE_CPUCAPACITY
|
5747 SD_SHARE_PKG_RESOURCES
|
5749 SD_SHARE_POWERDOMAIN
);
5750 if (nr_node_ids
== 1)
5751 pflags
&= ~SD_SERIALIZE
;
5753 if (~cflags
& pflags
)
5759 static void free_rootdomain(struct rcu_head
*rcu
)
5761 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5763 cpupri_cleanup(&rd
->cpupri
);
5764 cpudl_cleanup(&rd
->cpudl
);
5765 free_cpumask_var(rd
->dlo_mask
);
5766 free_cpumask_var(rd
->rto_mask
);
5767 free_cpumask_var(rd
->online
);
5768 free_cpumask_var(rd
->span
);
5772 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5774 struct root_domain
*old_rd
= NULL
;
5775 unsigned long flags
;
5777 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5782 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5785 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5788 * If we dont want to free the old_rd yet then
5789 * set old_rd to NULL to skip the freeing later
5792 if (!atomic_dec_and_test(&old_rd
->refcount
))
5796 atomic_inc(&rd
->refcount
);
5799 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5800 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5803 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5806 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5809 static int init_rootdomain(struct root_domain
*rd
)
5811 memset(rd
, 0, sizeof(*rd
));
5813 if (!zalloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5815 if (!zalloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5817 if (!zalloc_cpumask_var(&rd
->dlo_mask
, GFP_KERNEL
))
5819 if (!zalloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5822 init_dl_bw(&rd
->dl_bw
);
5823 if (cpudl_init(&rd
->cpudl
) != 0)
5826 if (cpupri_init(&rd
->cpupri
) != 0)
5831 free_cpumask_var(rd
->rto_mask
);
5833 free_cpumask_var(rd
->dlo_mask
);
5835 free_cpumask_var(rd
->online
);
5837 free_cpumask_var(rd
->span
);
5843 * By default the system creates a single root-domain with all cpus as
5844 * members (mimicking the global state we have today).
5846 struct root_domain def_root_domain
;
5848 static void init_defrootdomain(void)
5850 init_rootdomain(&def_root_domain
);
5852 atomic_set(&def_root_domain
.refcount
, 1);
5855 static struct root_domain
*alloc_rootdomain(void)
5857 struct root_domain
*rd
;
5859 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
5863 if (init_rootdomain(rd
) != 0) {
5871 static void free_sched_groups(struct sched_group
*sg
, int free_sgc
)
5873 struct sched_group
*tmp
, *first
;
5882 if (free_sgc
&& atomic_dec_and_test(&sg
->sgc
->ref
))
5887 } while (sg
!= first
);
5890 static void free_sched_domain(struct rcu_head
*rcu
)
5892 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
5895 * If its an overlapping domain it has private groups, iterate and
5898 if (sd
->flags
& SD_OVERLAP
) {
5899 free_sched_groups(sd
->groups
, 1);
5900 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
5901 kfree(sd
->groups
->sgc
);
5907 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
5909 call_rcu(&sd
->rcu
, free_sched_domain
);
5912 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
5914 for (; sd
; sd
= sd
->parent
)
5915 destroy_sched_domain(sd
, cpu
);
5919 * Keep a special pointer to the highest sched_domain that has
5920 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5921 * allows us to avoid some pointer chasing select_idle_sibling().
5923 * Also keep a unique ID per domain (we use the first cpu number in
5924 * the cpumask of the domain), this allows us to quickly tell if
5925 * two cpus are in the same cache domain, see cpus_share_cache().
5927 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
5928 DEFINE_PER_CPU(int, sd_llc_size
);
5929 DEFINE_PER_CPU(int, sd_llc_id
);
5930 DEFINE_PER_CPU(struct sched_domain
*, sd_numa
);
5931 DEFINE_PER_CPU(struct sched_domain
*, sd_busy
);
5932 DEFINE_PER_CPU(struct sched_domain
*, sd_asym
);
5934 static void update_top_cache_domain(int cpu
)
5936 struct sched_domain
*sd
;
5937 struct sched_domain
*busy_sd
= NULL
;
5941 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
5943 id
= cpumask_first(sched_domain_span(sd
));
5944 size
= cpumask_weight(sched_domain_span(sd
));
5945 busy_sd
= sd
->parent
; /* sd_busy */
5947 rcu_assign_pointer(per_cpu(sd_busy
, cpu
), busy_sd
);
5949 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
5950 per_cpu(sd_llc_size
, cpu
) = size
;
5951 per_cpu(sd_llc_id
, cpu
) = id
;
5953 sd
= lowest_flag_domain(cpu
, SD_NUMA
);
5954 rcu_assign_pointer(per_cpu(sd_numa
, cpu
), sd
);
5956 sd
= highest_flag_domain(cpu
, SD_ASYM_PACKING
);
5957 rcu_assign_pointer(per_cpu(sd_asym
, cpu
), sd
);
5961 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5962 * hold the hotplug lock.
5965 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
5967 struct rq
*rq
= cpu_rq(cpu
);
5968 struct sched_domain
*tmp
;
5970 /* Remove the sched domains which do not contribute to scheduling. */
5971 for (tmp
= sd
; tmp
; ) {
5972 struct sched_domain
*parent
= tmp
->parent
;
5976 if (sd_parent_degenerate(tmp
, parent
)) {
5977 tmp
->parent
= parent
->parent
;
5979 parent
->parent
->child
= tmp
;
5981 * Transfer SD_PREFER_SIBLING down in case of a
5982 * degenerate parent; the spans match for this
5983 * so the property transfers.
5985 if (parent
->flags
& SD_PREFER_SIBLING
)
5986 tmp
->flags
|= SD_PREFER_SIBLING
;
5987 destroy_sched_domain(parent
, cpu
);
5992 if (sd
&& sd_degenerate(sd
)) {
5995 destroy_sched_domain(tmp
, cpu
);
6000 sched_domain_debug(sd
, cpu
);
6002 rq_attach_root(rq
, rd
);
6004 rcu_assign_pointer(rq
->sd
, sd
);
6005 destroy_sched_domains(tmp
, cpu
);
6007 update_top_cache_domain(cpu
);
6010 /* Setup the mask of cpus configured for isolated domains */
6011 static int __init
isolated_cpu_setup(char *str
)
6015 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
6016 ret
= cpulist_parse(str
, cpu_isolated_map
);
6018 pr_err("sched: Error, all isolcpus= values must be between 0 and %d\n", nr_cpu_ids
);
6023 __setup("isolcpus=", isolated_cpu_setup
);
6026 struct sched_domain
** __percpu sd
;
6027 struct root_domain
*rd
;
6038 * Build an iteration mask that can exclude certain CPUs from the upwards
6041 * Asymmetric node setups can result in situations where the domain tree is of
6042 * unequal depth, make sure to skip domains that already cover the entire
6045 * In that case build_sched_domains() will have terminated the iteration early
6046 * and our sibling sd spans will be empty. Domains should always include the
6047 * cpu they're built on, so check that.
6050 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
6052 const struct cpumask
*span
= sched_domain_span(sd
);
6053 struct sd_data
*sdd
= sd
->private;
6054 struct sched_domain
*sibling
;
6057 for_each_cpu(i
, span
) {
6058 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
6059 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
6062 cpumask_set_cpu(i
, sched_group_mask(sg
));
6067 * Return the canonical balance cpu for this group, this is the first cpu
6068 * of this group that's also in the iteration mask.
6070 int group_balance_cpu(struct sched_group
*sg
)
6072 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
6076 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
6078 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
6079 const struct cpumask
*span
= sched_domain_span(sd
);
6080 struct cpumask
*covered
= sched_domains_tmpmask
;
6081 struct sd_data
*sdd
= sd
->private;
6082 struct sched_domain
*sibling
;
6085 cpumask_clear(covered
);
6087 for_each_cpu(i
, span
) {
6088 struct cpumask
*sg_span
;
6090 if (cpumask_test_cpu(i
, covered
))
6093 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
6095 /* See the comment near build_group_mask(). */
6096 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
6099 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6100 GFP_KERNEL
, cpu_to_node(cpu
));
6105 sg_span
= sched_group_cpus(sg
);
6107 cpumask_copy(sg_span
, sched_domain_span(sibling
->child
));
6109 cpumask_set_cpu(i
, sg_span
);
6111 cpumask_or(covered
, covered
, sg_span
);
6113 sg
->sgc
= *per_cpu_ptr(sdd
->sgc
, i
);
6114 if (atomic_inc_return(&sg
->sgc
->ref
) == 1)
6115 build_group_mask(sd
, sg
);
6118 * Initialize sgc->capacity such that even if we mess up the
6119 * domains and no possible iteration will get us here, we won't
6122 sg
->sgc
->capacity
= SCHED_CAPACITY_SCALE
* cpumask_weight(sg_span
);
6125 * Make sure the first group of this domain contains the
6126 * canonical balance cpu. Otherwise the sched_domain iteration
6127 * breaks. See update_sg_lb_stats().
6129 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
6130 group_balance_cpu(sg
) == cpu
)
6140 sd
->groups
= groups
;
6145 free_sched_groups(first
, 0);
6150 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
6152 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
6153 struct sched_domain
*child
= sd
->child
;
6156 cpu
= cpumask_first(sched_domain_span(child
));
6159 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
6160 (*sg
)->sgc
= *per_cpu_ptr(sdd
->sgc
, cpu
);
6161 atomic_set(&(*sg
)->sgc
->ref
, 1); /* for claim_allocations */
6168 * build_sched_groups will build a circular linked list of the groups
6169 * covered by the given span, and will set each group's ->cpumask correctly,
6170 * and ->cpu_capacity to 0.
6172 * Assumes the sched_domain tree is fully constructed
6175 build_sched_groups(struct sched_domain
*sd
, int cpu
)
6177 struct sched_group
*first
= NULL
, *last
= NULL
;
6178 struct sd_data
*sdd
= sd
->private;
6179 const struct cpumask
*span
= sched_domain_span(sd
);
6180 struct cpumask
*covered
;
6183 get_group(cpu
, sdd
, &sd
->groups
);
6184 atomic_inc(&sd
->groups
->ref
);
6186 if (cpu
!= cpumask_first(span
))
6189 lockdep_assert_held(&sched_domains_mutex
);
6190 covered
= sched_domains_tmpmask
;
6192 cpumask_clear(covered
);
6194 for_each_cpu(i
, span
) {
6195 struct sched_group
*sg
;
6198 if (cpumask_test_cpu(i
, covered
))
6201 group
= get_group(i
, sdd
, &sg
);
6202 cpumask_setall(sched_group_mask(sg
));
6204 for_each_cpu(j
, span
) {
6205 if (get_group(j
, sdd
, NULL
) != group
)
6208 cpumask_set_cpu(j
, covered
);
6209 cpumask_set_cpu(j
, sched_group_cpus(sg
));
6224 * Initialize sched groups cpu_capacity.
6226 * cpu_capacity indicates the capacity of sched group, which is used while
6227 * distributing the load between different sched groups in a sched domain.
6228 * Typically cpu_capacity for all the groups in a sched domain will be same
6229 * unless there are asymmetries in the topology. If there are asymmetries,
6230 * group having more cpu_capacity will pickup more load compared to the
6231 * group having less cpu_capacity.
6233 static void init_sched_groups_capacity(int cpu
, struct sched_domain
*sd
)
6235 struct sched_group
*sg
= sd
->groups
;
6240 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
6242 } while (sg
!= sd
->groups
);
6244 if (cpu
!= group_balance_cpu(sg
))
6247 update_group_capacity(sd
, cpu
);
6248 atomic_set(&sg
->sgc
->nr_busy_cpus
, sg
->group_weight
);
6252 * Initializers for schedule domains
6253 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6256 static int default_relax_domain_level
= -1;
6257 int sched_domain_level_max
;
6259 static int __init
setup_relax_domain_level(char *str
)
6261 if (kstrtoint(str
, 0, &default_relax_domain_level
))
6262 pr_warn("Unable to set relax_domain_level\n");
6266 __setup("relax_domain_level=", setup_relax_domain_level
);
6268 static void set_domain_attribute(struct sched_domain
*sd
,
6269 struct sched_domain_attr
*attr
)
6273 if (!attr
|| attr
->relax_domain_level
< 0) {
6274 if (default_relax_domain_level
< 0)
6277 request
= default_relax_domain_level
;
6279 request
= attr
->relax_domain_level
;
6280 if (request
< sd
->level
) {
6281 /* turn off idle balance on this domain */
6282 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6284 /* turn on idle balance on this domain */
6285 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6289 static void __sdt_free(const struct cpumask
*cpu_map
);
6290 static int __sdt_alloc(const struct cpumask
*cpu_map
);
6292 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
6293 const struct cpumask
*cpu_map
)
6297 if (!atomic_read(&d
->rd
->refcount
))
6298 free_rootdomain(&d
->rd
->rcu
); /* fall through */
6300 free_percpu(d
->sd
); /* fall through */
6302 __sdt_free(cpu_map
); /* fall through */
6308 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
6309 const struct cpumask
*cpu_map
)
6311 memset(d
, 0, sizeof(*d
));
6313 if (__sdt_alloc(cpu_map
))
6314 return sa_sd_storage
;
6315 d
->sd
= alloc_percpu(struct sched_domain
*);
6317 return sa_sd_storage
;
6318 d
->rd
= alloc_rootdomain();
6321 return sa_rootdomain
;
6325 * NULL the sd_data elements we've used to build the sched_domain and
6326 * sched_group structure so that the subsequent __free_domain_allocs()
6327 * will not free the data we're using.
6329 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6331 struct sd_data
*sdd
= sd
->private;
6333 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6334 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6336 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6337 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6339 if (atomic_read(&(*per_cpu_ptr(sdd
->sgc
, cpu
))->ref
))
6340 *per_cpu_ptr(sdd
->sgc
, cpu
) = NULL
;
6344 static int sched_domains_numa_levels
;
6345 enum numa_topology_type sched_numa_topology_type
;
6346 static int *sched_domains_numa_distance
;
6347 int sched_max_numa_distance
;
6348 static struct cpumask
***sched_domains_numa_masks
;
6349 static int sched_domains_curr_level
;
6353 * SD_flags allowed in topology descriptions.
6355 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6356 * SD_SHARE_PKG_RESOURCES - describes shared caches
6357 * SD_NUMA - describes NUMA topologies
6358 * SD_SHARE_POWERDOMAIN - describes shared power domain
6361 * SD_ASYM_PACKING - describes SMT quirks
6363 #define TOPOLOGY_SD_FLAGS \
6364 (SD_SHARE_CPUCAPACITY | \
6365 SD_SHARE_PKG_RESOURCES | \
6368 SD_SHARE_POWERDOMAIN)
6370 static struct sched_domain
*
6371 sd_init(struct sched_domain_topology_level
*tl
, int cpu
)
6373 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6374 int sd_weight
, sd_flags
= 0;
6378 * Ugly hack to pass state to sd_numa_mask()...
6380 sched_domains_curr_level
= tl
->numa_level
;
6383 sd_weight
= cpumask_weight(tl
->mask(cpu
));
6386 sd_flags
= (*tl
->sd_flags
)();
6387 if (WARN_ONCE(sd_flags
& ~TOPOLOGY_SD_FLAGS
,
6388 "wrong sd_flags in topology description\n"))
6389 sd_flags
&= ~TOPOLOGY_SD_FLAGS
;
6391 *sd
= (struct sched_domain
){
6392 .min_interval
= sd_weight
,
6393 .max_interval
= 2*sd_weight
,
6395 .imbalance_pct
= 125,
6397 .cache_nice_tries
= 0,
6404 .flags
= 1*SD_LOAD_BALANCE
6405 | 1*SD_BALANCE_NEWIDLE
6410 | 0*SD_SHARE_CPUCAPACITY
6411 | 0*SD_SHARE_PKG_RESOURCES
6413 | 0*SD_PREFER_SIBLING
6418 .last_balance
= jiffies
,
6419 .balance_interval
= sd_weight
,
6421 .max_newidle_lb_cost
= 0,
6422 .next_decay_max_lb_cost
= jiffies
,
6423 #ifdef CONFIG_SCHED_DEBUG
6429 * Convert topological properties into behaviour.
6432 if (sd
->flags
& SD_SHARE_CPUCAPACITY
) {
6433 sd
->flags
|= SD_PREFER_SIBLING
;
6434 sd
->imbalance_pct
= 110;
6435 sd
->smt_gain
= 1178; /* ~15% */
6437 } else if (sd
->flags
& SD_SHARE_PKG_RESOURCES
) {
6438 sd
->imbalance_pct
= 117;
6439 sd
->cache_nice_tries
= 1;
6443 } else if (sd
->flags
& SD_NUMA
) {
6444 sd
->cache_nice_tries
= 2;
6448 sd
->flags
|= SD_SERIALIZE
;
6449 if (sched_domains_numa_distance
[tl
->numa_level
] > RECLAIM_DISTANCE
) {
6450 sd
->flags
&= ~(SD_BALANCE_EXEC
|
6457 sd
->flags
|= SD_PREFER_SIBLING
;
6458 sd
->cache_nice_tries
= 1;
6463 sd
->private = &tl
->data
;
6469 * Topology list, bottom-up.
6471 static struct sched_domain_topology_level default_topology
[] = {
6472 #ifdef CONFIG_SCHED_SMT
6473 { cpu_smt_mask
, cpu_smt_flags
, SD_INIT_NAME(SMT
) },
6475 #ifdef CONFIG_SCHED_MC
6476 { cpu_coregroup_mask
, cpu_core_flags
, SD_INIT_NAME(MC
) },
6478 { cpu_cpu_mask
, SD_INIT_NAME(DIE
) },
6482 static struct sched_domain_topology_level
*sched_domain_topology
=
6485 #define for_each_sd_topology(tl) \
6486 for (tl = sched_domain_topology; tl->mask; tl++)
6488 void set_sched_topology(struct sched_domain_topology_level
*tl
)
6490 sched_domain_topology
= tl
;
6495 static const struct cpumask
*sd_numa_mask(int cpu
)
6497 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6500 static void sched_numa_warn(const char *str
)
6502 static int done
= false;
6510 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6512 for (i
= 0; i
< nr_node_ids
; i
++) {
6513 printk(KERN_WARNING
" ");
6514 for (j
= 0; j
< nr_node_ids
; j
++)
6515 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6516 printk(KERN_CONT
"\n");
6518 printk(KERN_WARNING
"\n");
6521 bool find_numa_distance(int distance
)
6525 if (distance
== node_distance(0, 0))
6528 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6529 if (sched_domains_numa_distance
[i
] == distance
)
6537 * A system can have three types of NUMA topology:
6538 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6539 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6540 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6542 * The difference between a glueless mesh topology and a backplane
6543 * topology lies in whether communication between not directly
6544 * connected nodes goes through intermediary nodes (where programs
6545 * could run), or through backplane controllers. This affects
6546 * placement of programs.
6548 * The type of topology can be discerned with the following tests:
6549 * - If the maximum distance between any nodes is 1 hop, the system
6550 * is directly connected.
6551 * - If for two nodes A and B, located N > 1 hops away from each other,
6552 * there is an intermediary node C, which is < N hops away from both
6553 * nodes A and B, the system is a glueless mesh.
6555 static void init_numa_topology_type(void)
6559 n
= sched_max_numa_distance
;
6561 if (sched_domains_numa_levels
<= 1) {
6562 sched_numa_topology_type
= NUMA_DIRECT
;
6566 for_each_online_node(a
) {
6567 for_each_online_node(b
) {
6568 /* Find two nodes furthest removed from each other. */
6569 if (node_distance(a
, b
) < n
)
6572 /* Is there an intermediary node between a and b? */
6573 for_each_online_node(c
) {
6574 if (node_distance(a
, c
) < n
&&
6575 node_distance(b
, c
) < n
) {
6576 sched_numa_topology_type
=
6582 sched_numa_topology_type
= NUMA_BACKPLANE
;
6588 static void sched_init_numa(void)
6590 int next_distance
, curr_distance
= node_distance(0, 0);
6591 struct sched_domain_topology_level
*tl
;
6595 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6596 if (!sched_domains_numa_distance
)
6600 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6601 * unique distances in the node_distance() table.
6603 * Assumes node_distance(0,j) includes all distances in
6604 * node_distance(i,j) in order to avoid cubic time.
6606 next_distance
= curr_distance
;
6607 for (i
= 0; i
< nr_node_ids
; i
++) {
6608 for (j
= 0; j
< nr_node_ids
; j
++) {
6609 for (k
= 0; k
< nr_node_ids
; k
++) {
6610 int distance
= node_distance(i
, k
);
6612 if (distance
> curr_distance
&&
6613 (distance
< next_distance
||
6614 next_distance
== curr_distance
))
6615 next_distance
= distance
;
6618 * While not a strong assumption it would be nice to know
6619 * about cases where if node A is connected to B, B is not
6620 * equally connected to A.
6622 if (sched_debug() && node_distance(k
, i
) != distance
)
6623 sched_numa_warn("Node-distance not symmetric");
6625 if (sched_debug() && i
&& !find_numa_distance(distance
))
6626 sched_numa_warn("Node-0 not representative");
6628 if (next_distance
!= curr_distance
) {
6629 sched_domains_numa_distance
[level
++] = next_distance
;
6630 sched_domains_numa_levels
= level
;
6631 curr_distance
= next_distance
;
6636 * In case of sched_debug() we verify the above assumption.
6646 * 'level' contains the number of unique distances, excluding the
6647 * identity distance node_distance(i,i).
6649 * The sched_domains_numa_distance[] array includes the actual distance
6654 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6655 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6656 * the array will contain less then 'level' members. This could be
6657 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6658 * in other functions.
6660 * We reset it to 'level' at the end of this function.
6662 sched_domains_numa_levels
= 0;
6664 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6665 if (!sched_domains_numa_masks
)
6669 * Now for each level, construct a mask per node which contains all
6670 * cpus of nodes that are that many hops away from us.
6672 for (i
= 0; i
< level
; i
++) {
6673 sched_domains_numa_masks
[i
] =
6674 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6675 if (!sched_domains_numa_masks
[i
])
6678 for (j
= 0; j
< nr_node_ids
; j
++) {
6679 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6683 sched_domains_numa_masks
[i
][j
] = mask
;
6686 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6689 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6694 /* Compute default topology size */
6695 for (i
= 0; sched_domain_topology
[i
].mask
; i
++);
6697 tl
= kzalloc((i
+ level
+ 1) *
6698 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6703 * Copy the default topology bits..
6705 for (i
= 0; sched_domain_topology
[i
].mask
; i
++)
6706 tl
[i
] = sched_domain_topology
[i
];
6709 * .. and append 'j' levels of NUMA goodness.
6711 for (j
= 0; j
< level
; i
++, j
++) {
6712 tl
[i
] = (struct sched_domain_topology_level
){
6713 .mask
= sd_numa_mask
,
6714 .sd_flags
= cpu_numa_flags
,
6715 .flags
= SDTL_OVERLAP
,
6721 sched_domain_topology
= tl
;
6723 sched_domains_numa_levels
= level
;
6724 sched_max_numa_distance
= sched_domains_numa_distance
[level
- 1];
6726 init_numa_topology_type();
6729 static void sched_domains_numa_masks_set(unsigned int cpu
)
6731 int node
= cpu_to_node(cpu
);
6734 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6735 for (j
= 0; j
< nr_node_ids
; j
++) {
6736 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6737 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6742 static void sched_domains_numa_masks_clear(unsigned int cpu
)
6746 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6747 for (j
= 0; j
< nr_node_ids
; j
++)
6748 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6753 static inline void sched_init_numa(void) { }
6754 static void sched_domains_numa_masks_set(unsigned int cpu
) { }
6755 static void sched_domains_numa_masks_clear(unsigned int cpu
) { }
6756 #endif /* CONFIG_NUMA */
6758 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6760 struct sched_domain_topology_level
*tl
;
6763 for_each_sd_topology(tl
) {
6764 struct sd_data
*sdd
= &tl
->data
;
6766 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6770 sdd
->sg
= alloc_percpu(struct sched_group
*);
6774 sdd
->sgc
= alloc_percpu(struct sched_group_capacity
*);
6778 for_each_cpu(j
, cpu_map
) {
6779 struct sched_domain
*sd
;
6780 struct sched_group
*sg
;
6781 struct sched_group_capacity
*sgc
;
6783 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6784 GFP_KERNEL
, cpu_to_node(j
));
6788 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6790 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6791 GFP_KERNEL
, cpu_to_node(j
));
6797 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6799 sgc
= kzalloc_node(sizeof(struct sched_group_capacity
) + cpumask_size(),
6800 GFP_KERNEL
, cpu_to_node(j
));
6804 *per_cpu_ptr(sdd
->sgc
, j
) = sgc
;
6811 static void __sdt_free(const struct cpumask
*cpu_map
)
6813 struct sched_domain_topology_level
*tl
;
6816 for_each_sd_topology(tl
) {
6817 struct sd_data
*sdd
= &tl
->data
;
6819 for_each_cpu(j
, cpu_map
) {
6820 struct sched_domain
*sd
;
6823 sd
= *per_cpu_ptr(sdd
->sd
, j
);
6824 if (sd
&& (sd
->flags
& SD_OVERLAP
))
6825 free_sched_groups(sd
->groups
, 0);
6826 kfree(*per_cpu_ptr(sdd
->sd
, j
));
6830 kfree(*per_cpu_ptr(sdd
->sg
, j
));
6832 kfree(*per_cpu_ptr(sdd
->sgc
, j
));
6834 free_percpu(sdd
->sd
);
6836 free_percpu(sdd
->sg
);
6838 free_percpu(sdd
->sgc
);
6843 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
6844 const struct cpumask
*cpu_map
, struct sched_domain_attr
*attr
,
6845 struct sched_domain
*child
, int cpu
)
6847 struct sched_domain
*sd
= sd_init(tl
, cpu
);
6851 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
6853 sd
->level
= child
->level
+ 1;
6854 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
6858 if (!cpumask_subset(sched_domain_span(child
),
6859 sched_domain_span(sd
))) {
6860 pr_err("BUG: arch topology borken\n");
6861 #ifdef CONFIG_SCHED_DEBUG
6862 pr_err(" the %s domain not a subset of the %s domain\n",
6863 child
->name
, sd
->name
);
6865 /* Fixup, ensure @sd has at least @child cpus. */
6866 cpumask_or(sched_domain_span(sd
),
6867 sched_domain_span(sd
),
6868 sched_domain_span(child
));
6872 set_domain_attribute(sd
, attr
);
6878 * Build sched domains for a given set of cpus and attach the sched domains
6879 * to the individual cpus
6881 static int build_sched_domains(const struct cpumask
*cpu_map
,
6882 struct sched_domain_attr
*attr
)
6884 enum s_alloc alloc_state
;
6885 struct sched_domain
*sd
;
6887 int i
, ret
= -ENOMEM
;
6889 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
6890 if (alloc_state
!= sa_rootdomain
)
6893 /* Set up domains for cpus specified by the cpu_map. */
6894 for_each_cpu(i
, cpu_map
) {
6895 struct sched_domain_topology_level
*tl
;
6898 for_each_sd_topology(tl
) {
6899 sd
= build_sched_domain(tl
, cpu_map
, attr
, sd
, i
);
6900 if (tl
== sched_domain_topology
)
6901 *per_cpu_ptr(d
.sd
, i
) = sd
;
6902 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
6903 sd
->flags
|= SD_OVERLAP
;
6904 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
6909 /* Build the groups for the domains */
6910 for_each_cpu(i
, cpu_map
) {
6911 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6912 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
6913 if (sd
->flags
& SD_OVERLAP
) {
6914 if (build_overlap_sched_groups(sd
, i
))
6917 if (build_sched_groups(sd
, i
))
6923 /* Calculate CPU capacity for physical packages and nodes */
6924 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
6925 if (!cpumask_test_cpu(i
, cpu_map
))
6928 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6929 claim_allocations(i
, sd
);
6930 init_sched_groups_capacity(i
, sd
);
6934 /* Attach the domains */
6936 for_each_cpu(i
, cpu_map
) {
6937 sd
= *per_cpu_ptr(d
.sd
, i
);
6938 cpu_attach_domain(sd
, d
.rd
, i
);
6944 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
6948 static cpumask_var_t
*doms_cur
; /* current sched domains */
6949 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6950 static struct sched_domain_attr
*dattr_cur
;
6951 /* attribues of custom domains in 'doms_cur' */
6954 * Special case: If a kmalloc of a doms_cur partition (array of
6955 * cpumask) fails, then fallback to a single sched domain,
6956 * as determined by the single cpumask fallback_doms.
6958 static cpumask_var_t fallback_doms
;
6961 * arch_update_cpu_topology lets virtualized architectures update the
6962 * cpu core maps. It is supposed to return 1 if the topology changed
6963 * or 0 if it stayed the same.
6965 int __weak
arch_update_cpu_topology(void)
6970 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
6973 cpumask_var_t
*doms
;
6975 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
6978 for (i
= 0; i
< ndoms
; i
++) {
6979 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
6980 free_sched_domains(doms
, i
);
6987 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
6990 for (i
= 0; i
< ndoms
; i
++)
6991 free_cpumask_var(doms
[i
]);
6996 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6997 * For now this just excludes isolated cpus, but could be used to
6998 * exclude other special cases in the future.
7000 static int init_sched_domains(const struct cpumask
*cpu_map
)
7004 arch_update_cpu_topology();
7006 doms_cur
= alloc_sched_domains(ndoms_cur
);
7008 doms_cur
= &fallback_doms
;
7009 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
7010 err
= build_sched_domains(doms_cur
[0], NULL
);
7011 register_sched_domain_sysctl();
7017 * Detach sched domains from a group of cpus specified in cpu_map
7018 * These cpus will now be attached to the NULL domain
7020 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
7025 for_each_cpu(i
, cpu_map
)
7026 cpu_attach_domain(NULL
, &def_root_domain
, i
);
7030 /* handle null as "default" */
7031 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
7032 struct sched_domain_attr
*new, int idx_new
)
7034 struct sched_domain_attr tmp
;
7041 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
7042 new ? (new + idx_new
) : &tmp
,
7043 sizeof(struct sched_domain_attr
));
7047 * Partition sched domains as specified by the 'ndoms_new'
7048 * cpumasks in the array doms_new[] of cpumasks. This compares
7049 * doms_new[] to the current sched domain partitioning, doms_cur[].
7050 * It destroys each deleted domain and builds each new domain.
7052 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7053 * The masks don't intersect (don't overlap.) We should setup one
7054 * sched domain for each mask. CPUs not in any of the cpumasks will
7055 * not be load balanced. If the same cpumask appears both in the
7056 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7059 * The passed in 'doms_new' should be allocated using
7060 * alloc_sched_domains. This routine takes ownership of it and will
7061 * free_sched_domains it when done with it. If the caller failed the
7062 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7063 * and partition_sched_domains() will fallback to the single partition
7064 * 'fallback_doms', it also forces the domains to be rebuilt.
7066 * If doms_new == NULL it will be replaced with cpu_online_mask.
7067 * ndoms_new == 0 is a special case for destroying existing domains,
7068 * and it will not create the default domain.
7070 * Call with hotplug lock held
7072 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
7073 struct sched_domain_attr
*dattr_new
)
7078 mutex_lock(&sched_domains_mutex
);
7080 /* always unregister in case we don't destroy any domains */
7081 unregister_sched_domain_sysctl();
7083 /* Let architecture update cpu core mappings. */
7084 new_topology
= arch_update_cpu_topology();
7086 n
= doms_new
? ndoms_new
: 0;
7088 /* Destroy deleted domains */
7089 for (i
= 0; i
< ndoms_cur
; i
++) {
7090 for (j
= 0; j
< n
&& !new_topology
; j
++) {
7091 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
7092 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
7095 /* no match - a current sched domain not in new doms_new[] */
7096 detach_destroy_domains(doms_cur
[i
]);
7102 if (doms_new
== NULL
) {
7104 doms_new
= &fallback_doms
;
7105 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
7106 WARN_ON_ONCE(dattr_new
);
7109 /* Build new domains */
7110 for (i
= 0; i
< ndoms_new
; i
++) {
7111 for (j
= 0; j
< n
&& !new_topology
; j
++) {
7112 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
7113 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
7116 /* no match - add a new doms_new */
7117 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
7122 /* Remember the new sched domains */
7123 if (doms_cur
!= &fallback_doms
)
7124 free_sched_domains(doms_cur
, ndoms_cur
);
7125 kfree(dattr_cur
); /* kfree(NULL) is safe */
7126 doms_cur
= doms_new
;
7127 dattr_cur
= dattr_new
;
7128 ndoms_cur
= ndoms_new
;
7130 register_sched_domain_sysctl();
7132 mutex_unlock(&sched_domains_mutex
);
7135 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
7138 * Update cpusets according to cpu_active mask. If cpusets are
7139 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7140 * around partition_sched_domains().
7142 * If we come here as part of a suspend/resume, don't touch cpusets because we
7143 * want to restore it back to its original state upon resume anyway.
7145 static void cpuset_cpu_active(void)
7147 if (cpuhp_tasks_frozen
) {
7149 * num_cpus_frozen tracks how many CPUs are involved in suspend
7150 * resume sequence. As long as this is not the last online
7151 * operation in the resume sequence, just build a single sched
7152 * domain, ignoring cpusets.
7155 if (likely(num_cpus_frozen
)) {
7156 partition_sched_domains(1, NULL
, NULL
);
7160 * This is the last CPU online operation. So fall through and
7161 * restore the original sched domains by considering the
7162 * cpuset configurations.
7165 cpuset_update_active_cpus(true);
7168 static int cpuset_cpu_inactive(unsigned int cpu
)
7170 unsigned long flags
;
7175 if (!cpuhp_tasks_frozen
) {
7176 rcu_read_lock_sched();
7177 dl_b
= dl_bw_of(cpu
);
7179 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
7180 cpus
= dl_bw_cpus(cpu
);
7181 overflow
= __dl_overflow(dl_b
, cpus
, 0, 0);
7182 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
7184 rcu_read_unlock_sched();
7188 cpuset_update_active_cpus(false);
7191 partition_sched_domains(1, NULL
, NULL
);
7196 int sched_cpu_activate(unsigned int cpu
)
7198 struct rq
*rq
= cpu_rq(cpu
);
7199 unsigned long flags
;
7201 set_cpu_active(cpu
, true);
7203 if (sched_smp_initialized
) {
7204 sched_domains_numa_masks_set(cpu
);
7205 cpuset_cpu_active();
7209 * Put the rq online, if not already. This happens:
7211 * 1) In the early boot process, because we build the real domains
7212 * after all cpus have been brought up.
7214 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
7217 raw_spin_lock_irqsave(&rq
->lock
, flags
);
7219 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
7222 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
7224 update_max_interval();
7229 int sched_cpu_deactivate(unsigned int cpu
)
7233 set_cpu_active(cpu
, false);
7235 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
7236 * users of this state to go away such that all new such users will
7239 * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
7240 * not imply sync_sched(), so wait for both.
7242 * Do sync before park smpboot threads to take care the rcu boost case.
7244 if (IS_ENABLED(CONFIG_PREEMPT
))
7245 synchronize_rcu_mult(call_rcu
, call_rcu_sched
);
7249 if (!sched_smp_initialized
)
7252 ret
= cpuset_cpu_inactive(cpu
);
7254 set_cpu_active(cpu
, true);
7257 sched_domains_numa_masks_clear(cpu
);
7261 static void sched_rq_cpu_starting(unsigned int cpu
)
7263 struct rq
*rq
= cpu_rq(cpu
);
7265 rq
->calc_load_update
= calc_load_update
;
7266 update_max_interval();
7269 int sched_cpu_starting(unsigned int cpu
)
7271 set_cpu_rq_start_time(cpu
);
7272 sched_rq_cpu_starting(cpu
);
7276 #ifdef CONFIG_HOTPLUG_CPU
7277 int sched_cpu_dying(unsigned int cpu
)
7279 struct rq
*rq
= cpu_rq(cpu
);
7280 unsigned long flags
;
7282 /* Handle pending wakeups and then migrate everything off */
7283 sched_ttwu_pending();
7284 raw_spin_lock_irqsave(&rq
->lock
, flags
);
7286 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
7290 BUG_ON(rq
->nr_running
!= 1);
7291 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
7292 calc_load_migrate(rq
);
7293 update_max_interval();
7294 nohz_balance_exit_idle(cpu
);
7300 void __init
sched_init_smp(void)
7302 cpumask_var_t non_isolated_cpus
;
7304 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
7305 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
7310 * There's no userspace yet to cause hotplug operations; hence all the
7311 * cpu masks are stable and all blatant races in the below code cannot
7314 mutex_lock(&sched_domains_mutex
);
7315 init_sched_domains(cpu_active_mask
);
7316 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
7317 if (cpumask_empty(non_isolated_cpus
))
7318 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
7319 mutex_unlock(&sched_domains_mutex
);
7321 /* Move init over to a non-isolated CPU */
7322 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
7324 sched_init_granularity();
7325 free_cpumask_var(non_isolated_cpus
);
7327 init_sched_rt_class();
7328 init_sched_dl_class();
7329 sched_smp_initialized
= true;
7332 static int __init
migration_init(void)
7334 sched_rq_cpu_starting(smp_processor_id());
7337 early_initcall(migration_init
);
7340 void __init
sched_init_smp(void)
7342 sched_init_granularity();
7344 #endif /* CONFIG_SMP */
7346 int in_sched_functions(unsigned long addr
)
7348 return in_lock_functions(addr
) ||
7349 (addr
>= (unsigned long)__sched_text_start
7350 && addr
< (unsigned long)__sched_text_end
);
7353 #ifdef CONFIG_CGROUP_SCHED
7355 * Default task group.
7356 * Every task in system belongs to this group at bootup.
7358 struct task_group root_task_group
;
7359 LIST_HEAD(task_groups
);
7361 /* Cacheline aligned slab cache for task_group */
7362 static struct kmem_cache
*task_group_cache __read_mostly
;
7365 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
7367 void __init
sched_init(void)
7370 unsigned long alloc_size
= 0, ptr
;
7372 #ifdef CONFIG_FAIR_GROUP_SCHED
7373 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7375 #ifdef CONFIG_RT_GROUP_SCHED
7376 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7379 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
7381 #ifdef CONFIG_FAIR_GROUP_SCHED
7382 root_task_group
.se
= (struct sched_entity
**)ptr
;
7383 ptr
+= nr_cpu_ids
* sizeof(void **);
7385 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
7386 ptr
+= nr_cpu_ids
* sizeof(void **);
7388 #endif /* CONFIG_FAIR_GROUP_SCHED */
7389 #ifdef CONFIG_RT_GROUP_SCHED
7390 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
7391 ptr
+= nr_cpu_ids
* sizeof(void **);
7393 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
7394 ptr
+= nr_cpu_ids
* sizeof(void **);
7396 #endif /* CONFIG_RT_GROUP_SCHED */
7398 #ifdef CONFIG_CPUMASK_OFFSTACK
7399 for_each_possible_cpu(i
) {
7400 per_cpu(load_balance_mask
, i
) = (cpumask_var_t
)kzalloc_node(
7401 cpumask_size(), GFP_KERNEL
, cpu_to_node(i
));
7403 #endif /* CONFIG_CPUMASK_OFFSTACK */
7405 init_rt_bandwidth(&def_rt_bandwidth
,
7406 global_rt_period(), global_rt_runtime());
7407 init_dl_bandwidth(&def_dl_bandwidth
,
7408 global_rt_period(), global_rt_runtime());
7411 init_defrootdomain();
7414 #ifdef CONFIG_RT_GROUP_SCHED
7415 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
7416 global_rt_period(), global_rt_runtime());
7417 #endif /* CONFIG_RT_GROUP_SCHED */
7419 #ifdef CONFIG_CGROUP_SCHED
7420 task_group_cache
= KMEM_CACHE(task_group
, 0);
7422 list_add(&root_task_group
.list
, &task_groups
);
7423 INIT_LIST_HEAD(&root_task_group
.children
);
7424 INIT_LIST_HEAD(&root_task_group
.siblings
);
7425 autogroup_init(&init_task
);
7426 #endif /* CONFIG_CGROUP_SCHED */
7428 for_each_possible_cpu(i
) {
7432 raw_spin_lock_init(&rq
->lock
);
7434 rq
->calc_load_active
= 0;
7435 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
7436 init_cfs_rq(&rq
->cfs
);
7437 init_rt_rq(&rq
->rt
);
7438 init_dl_rq(&rq
->dl
);
7439 #ifdef CONFIG_FAIR_GROUP_SCHED
7440 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
7441 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
7443 * How much cpu bandwidth does root_task_group get?
7445 * In case of task-groups formed thr' the cgroup filesystem, it
7446 * gets 100% of the cpu resources in the system. This overall
7447 * system cpu resource is divided among the tasks of
7448 * root_task_group and its child task-groups in a fair manner,
7449 * based on each entity's (task or task-group's) weight
7450 * (se->load.weight).
7452 * In other words, if root_task_group has 10 tasks of weight
7453 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7454 * then A0's share of the cpu resource is:
7456 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7458 * We achieve this by letting root_task_group's tasks sit
7459 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7461 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
7462 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
7463 #endif /* CONFIG_FAIR_GROUP_SCHED */
7465 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
7466 #ifdef CONFIG_RT_GROUP_SCHED
7467 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
7470 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7471 rq
->cpu_load
[j
] = 0;
7476 rq
->cpu_capacity
= rq
->cpu_capacity_orig
= SCHED_CAPACITY_SCALE
;
7477 rq
->balance_callback
= NULL
;
7478 rq
->active_balance
= 0;
7479 rq
->next_balance
= jiffies
;
7484 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
7485 rq
->max_idle_balance_cost
= sysctl_sched_migration_cost
;
7487 INIT_LIST_HEAD(&rq
->cfs_tasks
);
7489 rq_attach_root(rq
, &def_root_domain
);
7490 #ifdef CONFIG_NO_HZ_COMMON
7491 rq
->last_load_update_tick
= jiffies
;
7494 #ifdef CONFIG_NO_HZ_FULL
7495 rq
->last_sched_tick
= 0;
7497 #endif /* CONFIG_SMP */
7499 atomic_set(&rq
->nr_iowait
, 0);
7502 set_load_weight(&init_task
);
7504 #ifdef CONFIG_PREEMPT_NOTIFIERS
7505 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7509 * The boot idle thread does lazy MMU switching as well:
7511 atomic_inc(&init_mm
.mm_count
);
7512 enter_lazy_tlb(&init_mm
, current
);
7515 * During early bootup we pretend to be a normal task:
7517 current
->sched_class
= &fair_sched_class
;
7520 * Make us the idle thread. Technically, schedule() should not be
7521 * called from this thread, however somewhere below it might be,
7522 * but because we are the idle thread, we just pick up running again
7523 * when this runqueue becomes "idle".
7525 init_idle(current
, smp_processor_id());
7527 calc_load_update
= jiffies
+ LOAD_FREQ
;
7530 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
7531 /* May be allocated at isolcpus cmdline parse time */
7532 if (cpu_isolated_map
== NULL
)
7533 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
7534 idle_thread_set_boot_cpu();
7535 set_cpu_rq_start_time(smp_processor_id());
7537 init_sched_fair_class();
7541 scheduler_running
= 1;
7544 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7545 static inline int preempt_count_equals(int preempt_offset
)
7547 int nested
= preempt_count() + rcu_preempt_depth();
7549 return (nested
== preempt_offset
);
7552 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7555 * Blocking primitives will set (and therefore destroy) current->state,
7556 * since we will exit with TASK_RUNNING make sure we enter with it,
7557 * otherwise we will destroy state.
7559 WARN_ONCE(current
->state
!= TASK_RUNNING
&& current
->task_state_change
,
7560 "do not call blocking ops when !TASK_RUNNING; "
7561 "state=%lx set at [<%p>] %pS\n",
7563 (void *)current
->task_state_change
,
7564 (void *)current
->task_state_change
);
7566 ___might_sleep(file
, line
, preempt_offset
);
7568 EXPORT_SYMBOL(__might_sleep
);
7570 void ___might_sleep(const char *file
, int line
, int preempt_offset
)
7572 static unsigned long prev_jiffy
; /* ratelimiting */
7574 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7575 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled() &&
7576 !is_idle_task(current
)) ||
7577 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7579 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7581 prev_jiffy
= jiffies
;
7584 "BUG: sleeping function called from invalid context at %s:%d\n",
7587 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7588 in_atomic(), irqs_disabled(),
7589 current
->pid
, current
->comm
);
7591 if (task_stack_end_corrupted(current
))
7592 printk(KERN_EMERG
"Thread overran stack, or stack corrupted\n");
7594 debug_show_held_locks(current
);
7595 if (irqs_disabled())
7596 print_irqtrace_events(current
);
7597 #ifdef CONFIG_DEBUG_PREEMPT
7598 if (!preempt_count_equals(preempt_offset
)) {
7599 pr_err("Preemption disabled at:");
7600 print_ip_sym(current
->preempt_disable_ip
);
7606 EXPORT_SYMBOL(___might_sleep
);
7609 #ifdef CONFIG_MAGIC_SYSRQ
7610 void normalize_rt_tasks(void)
7612 struct task_struct
*g
, *p
;
7613 struct sched_attr attr
= {
7614 .sched_policy
= SCHED_NORMAL
,
7617 read_lock(&tasklist_lock
);
7618 for_each_process_thread(g
, p
) {
7620 * Only normalize user tasks:
7622 if (p
->flags
& PF_KTHREAD
)
7625 p
->se
.exec_start
= 0;
7626 #ifdef CONFIG_SCHEDSTATS
7627 p
->se
.statistics
.wait_start
= 0;
7628 p
->se
.statistics
.sleep_start
= 0;
7629 p
->se
.statistics
.block_start
= 0;
7632 if (!dl_task(p
) && !rt_task(p
)) {
7634 * Renice negative nice level userspace
7637 if (task_nice(p
) < 0)
7638 set_user_nice(p
, 0);
7642 __sched_setscheduler(p
, &attr
, false, false);
7644 read_unlock(&tasklist_lock
);
7647 #endif /* CONFIG_MAGIC_SYSRQ */
7649 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7651 * These functions are only useful for the IA64 MCA handling, or kdb.
7653 * They can only be called when the whole system has been
7654 * stopped - every CPU needs to be quiescent, and no scheduling
7655 * activity can take place. Using them for anything else would
7656 * be a serious bug, and as a result, they aren't even visible
7657 * under any other configuration.
7661 * curr_task - return the current task for a given cpu.
7662 * @cpu: the processor in question.
7664 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7666 * Return: The current task for @cpu.
7668 struct task_struct
*curr_task(int cpu
)
7670 return cpu_curr(cpu
);
7673 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7677 * set_curr_task - set the current task for a given cpu.
7678 * @cpu: the processor in question.
7679 * @p: the task pointer to set.
7681 * Description: This function must only be used when non-maskable interrupts
7682 * are serviced on a separate stack. It allows the architecture to switch the
7683 * notion of the current task on a cpu in a non-blocking manner. This function
7684 * must be called with all CPU's synchronized, and interrupts disabled, the
7685 * and caller must save the original value of the current task (see
7686 * curr_task() above) and restore that value before reenabling interrupts and
7687 * re-starting the system.
7689 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7691 void set_curr_task(int cpu
, struct task_struct
*p
)
7698 #ifdef CONFIG_CGROUP_SCHED
7699 /* task_group_lock serializes the addition/removal of task groups */
7700 static DEFINE_SPINLOCK(task_group_lock
);
7702 static void sched_free_group(struct task_group
*tg
)
7704 free_fair_sched_group(tg
);
7705 free_rt_sched_group(tg
);
7707 kmem_cache_free(task_group_cache
, tg
);
7710 /* allocate runqueue etc for a new task group */
7711 struct task_group
*sched_create_group(struct task_group
*parent
)
7713 struct task_group
*tg
;
7715 tg
= kmem_cache_alloc(task_group_cache
, GFP_KERNEL
| __GFP_ZERO
);
7717 return ERR_PTR(-ENOMEM
);
7719 if (!alloc_fair_sched_group(tg
, parent
))
7722 if (!alloc_rt_sched_group(tg
, parent
))
7728 sched_free_group(tg
);
7729 return ERR_PTR(-ENOMEM
);
7732 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7734 unsigned long flags
;
7736 spin_lock_irqsave(&task_group_lock
, flags
);
7737 list_add_rcu(&tg
->list
, &task_groups
);
7739 WARN_ON(!parent
); /* root should already exist */
7741 tg
->parent
= parent
;
7742 INIT_LIST_HEAD(&tg
->children
);
7743 list_add_rcu(&tg
->siblings
, &parent
->children
);
7744 spin_unlock_irqrestore(&task_group_lock
, flags
);
7746 online_fair_sched_group(tg
);
7749 /* rcu callback to free various structures associated with a task group */
7750 static void sched_free_group_rcu(struct rcu_head
*rhp
)
7752 /* now it should be safe to free those cfs_rqs */
7753 sched_free_group(container_of(rhp
, struct task_group
, rcu
));
7756 void sched_destroy_group(struct task_group
*tg
)
7758 /* wait for possible concurrent references to cfs_rqs complete */
7759 call_rcu(&tg
->rcu
, sched_free_group_rcu
);
7762 void sched_offline_group(struct task_group
*tg
)
7764 unsigned long flags
;
7766 /* end participation in shares distribution */
7767 unregister_fair_sched_group(tg
);
7769 spin_lock_irqsave(&task_group_lock
, flags
);
7770 list_del_rcu(&tg
->list
);
7771 list_del_rcu(&tg
->siblings
);
7772 spin_unlock_irqrestore(&task_group_lock
, flags
);
7775 static void sched_change_group(struct task_struct
*tsk
, int type
)
7777 struct task_group
*tg
;
7780 * All callers are synchronized by task_rq_lock(); we do not use RCU
7781 * which is pointless here. Thus, we pass "true" to task_css_check()
7782 * to prevent lockdep warnings.
7784 tg
= container_of(task_css_check(tsk
, cpu_cgrp_id
, true),
7785 struct task_group
, css
);
7786 tg
= autogroup_task_group(tsk
, tg
);
7787 tsk
->sched_task_group
= tg
;
7789 #ifdef CONFIG_FAIR_GROUP_SCHED
7790 if (tsk
->sched_class
->task_change_group
)
7791 tsk
->sched_class
->task_change_group(tsk
, type
);
7794 set_task_rq(tsk
, task_cpu(tsk
));
7798 * Change task's runqueue when it moves between groups.
7800 * The caller of this function should have put the task in its new group by
7801 * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
7804 void sched_move_task(struct task_struct
*tsk
)
7806 int queued
, running
;
7810 rq
= task_rq_lock(tsk
, &rf
);
7812 running
= task_current(rq
, tsk
);
7813 queued
= task_on_rq_queued(tsk
);
7816 dequeue_task(rq
, tsk
, DEQUEUE_SAVE
| DEQUEUE_MOVE
);
7817 if (unlikely(running
))
7818 put_prev_task(rq
, tsk
);
7820 sched_change_group(tsk
, TASK_MOVE_GROUP
);
7822 if (unlikely(running
))
7823 tsk
->sched_class
->set_curr_task(rq
);
7825 enqueue_task(rq
, tsk
, ENQUEUE_RESTORE
| ENQUEUE_MOVE
);
7827 task_rq_unlock(rq
, tsk
, &rf
);
7829 #endif /* CONFIG_CGROUP_SCHED */
7831 #ifdef CONFIG_RT_GROUP_SCHED
7833 * Ensure that the real time constraints are schedulable.
7835 static DEFINE_MUTEX(rt_constraints_mutex
);
7837 /* Must be called with tasklist_lock held */
7838 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7840 struct task_struct
*g
, *p
;
7843 * Autogroups do not have RT tasks; see autogroup_create().
7845 if (task_group_is_autogroup(tg
))
7848 for_each_process_thread(g
, p
) {
7849 if (rt_task(p
) && task_group(p
) == tg
)
7856 struct rt_schedulable_data
{
7857 struct task_group
*tg
;
7862 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7864 struct rt_schedulable_data
*d
= data
;
7865 struct task_group
*child
;
7866 unsigned long total
, sum
= 0;
7867 u64 period
, runtime
;
7869 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7870 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7873 period
= d
->rt_period
;
7874 runtime
= d
->rt_runtime
;
7878 * Cannot have more runtime than the period.
7880 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7884 * Ensure we don't starve existing RT tasks.
7886 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7889 total
= to_ratio(period
, runtime
);
7892 * Nobody can have more than the global setting allows.
7894 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7898 * The sum of our children's runtime should not exceed our own.
7900 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7901 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7902 runtime
= child
->rt_bandwidth
.rt_runtime
;
7904 if (child
== d
->tg
) {
7905 period
= d
->rt_period
;
7906 runtime
= d
->rt_runtime
;
7909 sum
+= to_ratio(period
, runtime
);
7918 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7922 struct rt_schedulable_data data
= {
7924 .rt_period
= period
,
7925 .rt_runtime
= runtime
,
7929 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
7935 static int tg_set_rt_bandwidth(struct task_group
*tg
,
7936 u64 rt_period
, u64 rt_runtime
)
7941 * Disallowing the root group RT runtime is BAD, it would disallow the
7942 * kernel creating (and or operating) RT threads.
7944 if (tg
== &root_task_group
&& rt_runtime
== 0)
7947 /* No period doesn't make any sense. */
7951 mutex_lock(&rt_constraints_mutex
);
7952 read_lock(&tasklist_lock
);
7953 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
7957 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7958 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
7959 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
7961 for_each_possible_cpu(i
) {
7962 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
7964 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7965 rt_rq
->rt_runtime
= rt_runtime
;
7966 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7968 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7970 read_unlock(&tasklist_lock
);
7971 mutex_unlock(&rt_constraints_mutex
);
7976 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7978 u64 rt_runtime
, rt_period
;
7980 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7981 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7982 if (rt_runtime_us
< 0)
7983 rt_runtime
= RUNTIME_INF
;
7985 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7988 static long sched_group_rt_runtime(struct task_group
*tg
)
7992 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
7995 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
7996 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7997 return rt_runtime_us
;
8000 static int sched_group_set_rt_period(struct task_group
*tg
, u64 rt_period_us
)
8002 u64 rt_runtime
, rt_period
;
8004 rt_period
= rt_period_us
* NSEC_PER_USEC
;
8005 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
8007 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
8010 static long sched_group_rt_period(struct task_group
*tg
)
8014 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8015 do_div(rt_period_us
, NSEC_PER_USEC
);
8016 return rt_period_us
;
8018 #endif /* CONFIG_RT_GROUP_SCHED */
8020 #ifdef CONFIG_RT_GROUP_SCHED
8021 static int sched_rt_global_constraints(void)
8025 mutex_lock(&rt_constraints_mutex
);
8026 read_lock(&tasklist_lock
);
8027 ret
= __rt_schedulable(NULL
, 0, 0);
8028 read_unlock(&tasklist_lock
);
8029 mutex_unlock(&rt_constraints_mutex
);
8034 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
8036 /* Don't accept realtime tasks when there is no way for them to run */
8037 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
8043 #else /* !CONFIG_RT_GROUP_SCHED */
8044 static int sched_rt_global_constraints(void)
8046 unsigned long flags
;
8049 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8050 for_each_possible_cpu(i
) {
8051 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
8053 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
8054 rt_rq
->rt_runtime
= global_rt_runtime();
8055 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
8057 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8061 #endif /* CONFIG_RT_GROUP_SCHED */
8063 static int sched_dl_global_validate(void)
8065 u64 runtime
= global_rt_runtime();
8066 u64 period
= global_rt_period();
8067 u64 new_bw
= to_ratio(period
, runtime
);
8070 unsigned long flags
;
8073 * Here we want to check the bandwidth not being set to some
8074 * value smaller than the currently allocated bandwidth in
8075 * any of the root_domains.
8077 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
8078 * cycling on root_domains... Discussion on different/better
8079 * solutions is welcome!
8081 for_each_possible_cpu(cpu
) {
8082 rcu_read_lock_sched();
8083 dl_b
= dl_bw_of(cpu
);
8085 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
8086 if (new_bw
< dl_b
->total_bw
)
8088 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
8090 rcu_read_unlock_sched();
8099 static void sched_dl_do_global(void)
8104 unsigned long flags
;
8106 def_dl_bandwidth
.dl_period
= global_rt_period();
8107 def_dl_bandwidth
.dl_runtime
= global_rt_runtime();
8109 if (global_rt_runtime() != RUNTIME_INF
)
8110 new_bw
= to_ratio(global_rt_period(), global_rt_runtime());
8113 * FIXME: As above...
8115 for_each_possible_cpu(cpu
) {
8116 rcu_read_lock_sched();
8117 dl_b
= dl_bw_of(cpu
);
8119 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
8121 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
8123 rcu_read_unlock_sched();
8127 static int sched_rt_global_validate(void)
8129 if (sysctl_sched_rt_period
<= 0)
8132 if ((sysctl_sched_rt_runtime
!= RUNTIME_INF
) &&
8133 (sysctl_sched_rt_runtime
> sysctl_sched_rt_period
))
8139 static void sched_rt_do_global(void)
8141 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
8142 def_rt_bandwidth
.rt_period
= ns_to_ktime(global_rt_period());
8145 int sched_rt_handler(struct ctl_table
*table
, int write
,
8146 void __user
*buffer
, size_t *lenp
,
8149 int old_period
, old_runtime
;
8150 static DEFINE_MUTEX(mutex
);
8154 old_period
= sysctl_sched_rt_period
;
8155 old_runtime
= sysctl_sched_rt_runtime
;
8157 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
8159 if (!ret
&& write
) {
8160 ret
= sched_rt_global_validate();
8164 ret
= sched_dl_global_validate();
8168 ret
= sched_rt_global_constraints();
8172 sched_rt_do_global();
8173 sched_dl_do_global();
8177 sysctl_sched_rt_period
= old_period
;
8178 sysctl_sched_rt_runtime
= old_runtime
;
8180 mutex_unlock(&mutex
);
8185 int sched_rr_handler(struct ctl_table
*table
, int write
,
8186 void __user
*buffer
, size_t *lenp
,
8190 static DEFINE_MUTEX(mutex
);
8193 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
8194 /* make sure that internally we keep jiffies */
8195 /* also, writing zero resets timeslice to default */
8196 if (!ret
&& write
) {
8197 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
8198 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
8200 mutex_unlock(&mutex
);
8204 #ifdef CONFIG_CGROUP_SCHED
8206 static inline struct task_group
*css_tg(struct cgroup_subsys_state
*css
)
8208 return css
? container_of(css
, struct task_group
, css
) : NULL
;
8211 static struct cgroup_subsys_state
*
8212 cpu_cgroup_css_alloc(struct cgroup_subsys_state
*parent_css
)
8214 struct task_group
*parent
= css_tg(parent_css
);
8215 struct task_group
*tg
;
8218 /* This is early initialization for the top cgroup */
8219 return &root_task_group
.css
;
8222 tg
= sched_create_group(parent
);
8224 return ERR_PTR(-ENOMEM
);
8226 sched_online_group(tg
, parent
);
8231 static void cpu_cgroup_css_released(struct cgroup_subsys_state
*css
)
8233 struct task_group
*tg
= css_tg(css
);
8235 sched_offline_group(tg
);
8238 static void cpu_cgroup_css_free(struct cgroup_subsys_state
*css
)
8240 struct task_group
*tg
= css_tg(css
);
8243 * Relies on the RCU grace period between css_released() and this.
8245 sched_free_group(tg
);
8249 * This is called before wake_up_new_task(), therefore we really only
8250 * have to set its group bits, all the other stuff does not apply.
8252 static void cpu_cgroup_fork(struct task_struct
*task
)
8257 rq
= task_rq_lock(task
, &rf
);
8259 sched_change_group(task
, TASK_SET_GROUP
);
8261 task_rq_unlock(rq
, task
, &rf
);
8264 static int cpu_cgroup_can_attach(struct cgroup_taskset
*tset
)
8266 struct task_struct
*task
;
8267 struct cgroup_subsys_state
*css
;
8270 cgroup_taskset_for_each(task
, css
, tset
) {
8271 #ifdef CONFIG_RT_GROUP_SCHED
8272 if (!sched_rt_can_attach(css_tg(css
), task
))
8275 /* We don't support RT-tasks being in separate groups */
8276 if (task
->sched_class
!= &fair_sched_class
)
8280 * Serialize against wake_up_new_task() such that if its
8281 * running, we're sure to observe its full state.
8283 raw_spin_lock_irq(&task
->pi_lock
);
8285 * Avoid calling sched_move_task() before wake_up_new_task()
8286 * has happened. This would lead to problems with PELT, due to
8287 * move wanting to detach+attach while we're not attached yet.
8289 if (task
->state
== TASK_NEW
)
8291 raw_spin_unlock_irq(&task
->pi_lock
);
8299 static void cpu_cgroup_attach(struct cgroup_taskset
*tset
)
8301 struct task_struct
*task
;
8302 struct cgroup_subsys_state
*css
;
8304 cgroup_taskset_for_each(task
, css
, tset
)
8305 sched_move_task(task
);
8308 #ifdef CONFIG_FAIR_GROUP_SCHED
8309 static int cpu_shares_write_u64(struct cgroup_subsys_state
*css
,
8310 struct cftype
*cftype
, u64 shareval
)
8312 return sched_group_set_shares(css_tg(css
), scale_load(shareval
));
8315 static u64
cpu_shares_read_u64(struct cgroup_subsys_state
*css
,
8318 struct task_group
*tg
= css_tg(css
);
8320 return (u64
) scale_load_down(tg
->shares
);
8323 #ifdef CONFIG_CFS_BANDWIDTH
8324 static DEFINE_MUTEX(cfs_constraints_mutex
);
8326 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
8327 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
8329 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
8331 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
8333 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
8334 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8336 if (tg
== &root_task_group
)
8340 * Ensure we have at some amount of bandwidth every period. This is
8341 * to prevent reaching a state of large arrears when throttled via
8342 * entity_tick() resulting in prolonged exit starvation.
8344 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
8348 * Likewise, bound things on the otherside by preventing insane quota
8349 * periods. This also allows us to normalize in computing quota
8352 if (period
> max_cfs_quota_period
)
8356 * Prevent race between setting of cfs_rq->runtime_enabled and
8357 * unthrottle_offline_cfs_rqs().
8360 mutex_lock(&cfs_constraints_mutex
);
8361 ret
= __cfs_schedulable(tg
, period
, quota
);
8365 runtime_enabled
= quota
!= RUNTIME_INF
;
8366 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
8368 * If we need to toggle cfs_bandwidth_used, off->on must occur
8369 * before making related changes, and on->off must occur afterwards
8371 if (runtime_enabled
&& !runtime_was_enabled
)
8372 cfs_bandwidth_usage_inc();
8373 raw_spin_lock_irq(&cfs_b
->lock
);
8374 cfs_b
->period
= ns_to_ktime(period
);
8375 cfs_b
->quota
= quota
;
8377 __refill_cfs_bandwidth_runtime(cfs_b
);
8378 /* restart the period timer (if active) to handle new period expiry */
8379 if (runtime_enabled
)
8380 start_cfs_bandwidth(cfs_b
);
8381 raw_spin_unlock_irq(&cfs_b
->lock
);
8383 for_each_online_cpu(i
) {
8384 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
8385 struct rq
*rq
= cfs_rq
->rq
;
8387 raw_spin_lock_irq(&rq
->lock
);
8388 cfs_rq
->runtime_enabled
= runtime_enabled
;
8389 cfs_rq
->runtime_remaining
= 0;
8391 if (cfs_rq
->throttled
)
8392 unthrottle_cfs_rq(cfs_rq
);
8393 raw_spin_unlock_irq(&rq
->lock
);
8395 if (runtime_was_enabled
&& !runtime_enabled
)
8396 cfs_bandwidth_usage_dec();
8398 mutex_unlock(&cfs_constraints_mutex
);
8404 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
8408 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8409 if (cfs_quota_us
< 0)
8410 quota
= RUNTIME_INF
;
8412 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
8414 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8417 long tg_get_cfs_quota(struct task_group
*tg
)
8421 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
8424 quota_us
= tg
->cfs_bandwidth
.quota
;
8425 do_div(quota_us
, NSEC_PER_USEC
);
8430 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
8434 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
8435 quota
= tg
->cfs_bandwidth
.quota
;
8437 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8440 long tg_get_cfs_period(struct task_group
*tg
)
8444 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8445 do_div(cfs_period_us
, NSEC_PER_USEC
);
8447 return cfs_period_us
;
8450 static s64
cpu_cfs_quota_read_s64(struct cgroup_subsys_state
*css
,
8453 return tg_get_cfs_quota(css_tg(css
));
8456 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state
*css
,
8457 struct cftype
*cftype
, s64 cfs_quota_us
)
8459 return tg_set_cfs_quota(css_tg(css
), cfs_quota_us
);
8462 static u64
cpu_cfs_period_read_u64(struct cgroup_subsys_state
*css
,
8465 return tg_get_cfs_period(css_tg(css
));
8468 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state
*css
,
8469 struct cftype
*cftype
, u64 cfs_period_us
)
8471 return tg_set_cfs_period(css_tg(css
), cfs_period_us
);
8474 struct cfs_schedulable_data
{
8475 struct task_group
*tg
;
8480 * normalize group quota/period to be quota/max_period
8481 * note: units are usecs
8483 static u64
normalize_cfs_quota(struct task_group
*tg
,
8484 struct cfs_schedulable_data
*d
)
8492 period
= tg_get_cfs_period(tg
);
8493 quota
= tg_get_cfs_quota(tg
);
8496 /* note: these should typically be equivalent */
8497 if (quota
== RUNTIME_INF
|| quota
== -1)
8500 return to_ratio(period
, quota
);
8503 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
8505 struct cfs_schedulable_data
*d
= data
;
8506 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8507 s64 quota
= 0, parent_quota
= -1;
8510 quota
= RUNTIME_INF
;
8512 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
8514 quota
= normalize_cfs_quota(tg
, d
);
8515 parent_quota
= parent_b
->hierarchical_quota
;
8518 * ensure max(child_quota) <= parent_quota, inherit when no
8521 if (quota
== RUNTIME_INF
)
8522 quota
= parent_quota
;
8523 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
8526 cfs_b
->hierarchical_quota
= quota
;
8531 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
8534 struct cfs_schedulable_data data
= {
8540 if (quota
!= RUNTIME_INF
) {
8541 do_div(data
.period
, NSEC_PER_USEC
);
8542 do_div(data
.quota
, NSEC_PER_USEC
);
8546 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
8552 static int cpu_stats_show(struct seq_file
*sf
, void *v
)
8554 struct task_group
*tg
= css_tg(seq_css(sf
));
8555 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8557 seq_printf(sf
, "nr_periods %d\n", cfs_b
->nr_periods
);
8558 seq_printf(sf
, "nr_throttled %d\n", cfs_b
->nr_throttled
);
8559 seq_printf(sf
, "throttled_time %llu\n", cfs_b
->throttled_time
);
8563 #endif /* CONFIG_CFS_BANDWIDTH */
8564 #endif /* CONFIG_FAIR_GROUP_SCHED */
8566 #ifdef CONFIG_RT_GROUP_SCHED
8567 static int cpu_rt_runtime_write(struct cgroup_subsys_state
*css
,
8568 struct cftype
*cft
, s64 val
)
8570 return sched_group_set_rt_runtime(css_tg(css
), val
);
8573 static s64
cpu_rt_runtime_read(struct cgroup_subsys_state
*css
,
8576 return sched_group_rt_runtime(css_tg(css
));
8579 static int cpu_rt_period_write_uint(struct cgroup_subsys_state
*css
,
8580 struct cftype
*cftype
, u64 rt_period_us
)
8582 return sched_group_set_rt_period(css_tg(css
), rt_period_us
);
8585 static u64
cpu_rt_period_read_uint(struct cgroup_subsys_state
*css
,
8588 return sched_group_rt_period(css_tg(css
));
8590 #endif /* CONFIG_RT_GROUP_SCHED */
8592 static struct cftype cpu_files
[] = {
8593 #ifdef CONFIG_FAIR_GROUP_SCHED
8596 .read_u64
= cpu_shares_read_u64
,
8597 .write_u64
= cpu_shares_write_u64
,
8600 #ifdef CONFIG_CFS_BANDWIDTH
8602 .name
= "cfs_quota_us",
8603 .read_s64
= cpu_cfs_quota_read_s64
,
8604 .write_s64
= cpu_cfs_quota_write_s64
,
8607 .name
= "cfs_period_us",
8608 .read_u64
= cpu_cfs_period_read_u64
,
8609 .write_u64
= cpu_cfs_period_write_u64
,
8613 .seq_show
= cpu_stats_show
,
8616 #ifdef CONFIG_RT_GROUP_SCHED
8618 .name
= "rt_runtime_us",
8619 .read_s64
= cpu_rt_runtime_read
,
8620 .write_s64
= cpu_rt_runtime_write
,
8623 .name
= "rt_period_us",
8624 .read_u64
= cpu_rt_period_read_uint
,
8625 .write_u64
= cpu_rt_period_write_uint
,
8631 struct cgroup_subsys cpu_cgrp_subsys
= {
8632 .css_alloc
= cpu_cgroup_css_alloc
,
8633 .css_released
= cpu_cgroup_css_released
,
8634 .css_free
= cpu_cgroup_css_free
,
8635 .fork
= cpu_cgroup_fork
,
8636 .can_attach
= cpu_cgroup_can_attach
,
8637 .attach
= cpu_cgroup_attach
,
8638 .legacy_cftypes
= cpu_files
,
8642 #endif /* CONFIG_CGROUP_SCHED */
8644 void dump_cpu_task(int cpu
)
8646 pr_info("Task dump for CPU %d:\n", cpu
);
8647 sched_show_task(cpu_curr(cpu
));
8651 * Nice levels are multiplicative, with a gentle 10% change for every
8652 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
8653 * nice 1, it will get ~10% less CPU time than another CPU-bound task
8654 * that remained on nice 0.
8656 * The "10% effect" is relative and cumulative: from _any_ nice level,
8657 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
8658 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
8659 * If a task goes up by ~10% and another task goes down by ~10% then
8660 * the relative distance between them is ~25%.)
8662 const int sched_prio_to_weight
[40] = {
8663 /* -20 */ 88761, 71755, 56483, 46273, 36291,
8664 /* -15 */ 29154, 23254, 18705, 14949, 11916,
8665 /* -10 */ 9548, 7620, 6100, 4904, 3906,
8666 /* -5 */ 3121, 2501, 1991, 1586, 1277,
8667 /* 0 */ 1024, 820, 655, 526, 423,
8668 /* 5 */ 335, 272, 215, 172, 137,
8669 /* 10 */ 110, 87, 70, 56, 45,
8670 /* 15 */ 36, 29, 23, 18, 15,
8674 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
8676 * In cases where the weight does not change often, we can use the
8677 * precalculated inverse to speed up arithmetics by turning divisions
8678 * into multiplications:
8680 const u32 sched_prio_to_wmult
[40] = {
8681 /* -20 */ 48388, 59856, 76040, 92818, 118348,
8682 /* -15 */ 147320, 184698, 229616, 287308, 360437,
8683 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
8684 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
8685 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
8686 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
8687 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
8688 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,