4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/debugfs.h>
70 #include <linux/ctype.h>
71 #include <linux/ftrace.h>
72 #include <linux/slab.h>
73 #include <linux/init_task.h>
74 #include <linux/binfmts.h>
75 #include <linux/context_tracking.h>
77 #include <asm/switch_to.h>
79 #include <asm/irq_regs.h>
80 #include <asm/mutex.h>
81 #ifdef CONFIG_PARAVIRT
82 #include <asm/paravirt.h>
86 #include "../workqueue_internal.h"
87 #include "../smpboot.h"
89 #define CREATE_TRACE_POINTS
90 #include <trace/events/sched.h>
92 void start_bandwidth_timer(struct hrtimer
*period_timer
, ktime_t period
)
95 ktime_t soft
, hard
, now
;
98 if (hrtimer_active(period_timer
))
101 now
= hrtimer_cb_get_time(period_timer
);
102 hrtimer_forward(period_timer
, now
, period
);
104 soft
= hrtimer_get_softexpires(period_timer
);
105 hard
= hrtimer_get_expires(period_timer
);
106 delta
= ktime_to_ns(ktime_sub(hard
, soft
));
107 __hrtimer_start_range_ns(period_timer
, soft
, delta
,
108 HRTIMER_MODE_ABS_PINNED
, 0);
112 DEFINE_MUTEX(sched_domains_mutex
);
113 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
115 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
117 void update_rq_clock(struct rq
*rq
)
121 if (rq
->skip_clock_update
> 0)
124 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
126 update_rq_clock_task(rq
, delta
);
130 * Debugging: various feature bits
133 #define SCHED_FEAT(name, enabled) \
134 (1UL << __SCHED_FEAT_##name) * enabled |
136 const_debug
unsigned int sysctl_sched_features
=
137 #include "features.h"
142 #ifdef CONFIG_SCHED_DEBUG
143 #define SCHED_FEAT(name, enabled) \
146 static const char * const sched_feat_names
[] = {
147 #include "features.h"
152 static int sched_feat_show(struct seq_file
*m
, void *v
)
156 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
157 if (!(sysctl_sched_features
& (1UL << i
)))
159 seq_printf(m
, "%s ", sched_feat_names
[i
]);
166 #ifdef HAVE_JUMP_LABEL
168 #define jump_label_key__true STATIC_KEY_INIT_TRUE
169 #define jump_label_key__false STATIC_KEY_INIT_FALSE
171 #define SCHED_FEAT(name, enabled) \
172 jump_label_key__##enabled ,
174 struct static_key sched_feat_keys
[__SCHED_FEAT_NR
] = {
175 #include "features.h"
180 static void sched_feat_disable(int i
)
182 if (static_key_enabled(&sched_feat_keys
[i
]))
183 static_key_slow_dec(&sched_feat_keys
[i
]);
186 static void sched_feat_enable(int i
)
188 if (!static_key_enabled(&sched_feat_keys
[i
]))
189 static_key_slow_inc(&sched_feat_keys
[i
]);
192 static void sched_feat_disable(int i
) { };
193 static void sched_feat_enable(int i
) { };
194 #endif /* HAVE_JUMP_LABEL */
196 static int sched_feat_set(char *cmp
)
201 if (strncmp(cmp
, "NO_", 3) == 0) {
206 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
207 if (strcmp(cmp
, sched_feat_names
[i
]) == 0) {
209 sysctl_sched_features
&= ~(1UL << i
);
210 sched_feat_disable(i
);
212 sysctl_sched_features
|= (1UL << i
);
213 sched_feat_enable(i
);
223 sched_feat_write(struct file
*filp
, const char __user
*ubuf
,
224 size_t cnt
, loff_t
*ppos
)
233 if (copy_from_user(&buf
, ubuf
, cnt
))
239 i
= sched_feat_set(cmp
);
240 if (i
== __SCHED_FEAT_NR
)
248 static int sched_feat_open(struct inode
*inode
, struct file
*filp
)
250 return single_open(filp
, sched_feat_show
, NULL
);
253 static const struct file_operations sched_feat_fops
= {
254 .open
= sched_feat_open
,
255 .write
= sched_feat_write
,
258 .release
= single_release
,
261 static __init
int sched_init_debug(void)
263 debugfs_create_file("sched_features", 0644, NULL
, NULL
,
268 late_initcall(sched_init_debug
);
269 #endif /* CONFIG_SCHED_DEBUG */
272 * Number of tasks to iterate in a single balance run.
273 * Limited because this is done with IRQs disabled.
275 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
278 * period over which we average the RT time consumption, measured
283 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
286 * period over which we measure -rt task cpu usage in us.
289 unsigned int sysctl_sched_rt_period
= 1000000;
291 __read_mostly
int scheduler_running
;
294 * part of the period that we allow rt tasks to run in us.
297 int sysctl_sched_rt_runtime
= 950000;
302 * __task_rq_lock - lock the rq @p resides on.
304 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
309 lockdep_assert_held(&p
->pi_lock
);
313 raw_spin_lock(&rq
->lock
);
314 if (likely(rq
== task_rq(p
)))
316 raw_spin_unlock(&rq
->lock
);
321 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
323 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
324 __acquires(p
->pi_lock
)
330 raw_spin_lock_irqsave(&p
->pi_lock
, *flags
);
332 raw_spin_lock(&rq
->lock
);
333 if (likely(rq
== task_rq(p
)))
335 raw_spin_unlock(&rq
->lock
);
336 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
340 static void __task_rq_unlock(struct rq
*rq
)
343 raw_spin_unlock(&rq
->lock
);
347 task_rq_unlock(struct rq
*rq
, struct task_struct
*p
, unsigned long *flags
)
349 __releases(p
->pi_lock
)
351 raw_spin_unlock(&rq
->lock
);
352 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
356 * this_rq_lock - lock this runqueue and disable interrupts.
358 static struct rq
*this_rq_lock(void)
365 raw_spin_lock(&rq
->lock
);
370 #ifdef CONFIG_SCHED_HRTICK
372 * Use HR-timers to deliver accurate preemption points.
374 * Its all a bit involved since we cannot program an hrt while holding the
375 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
378 * When we get rescheduled we reprogram the hrtick_timer outside of the
382 static void hrtick_clear(struct rq
*rq
)
384 if (hrtimer_active(&rq
->hrtick_timer
))
385 hrtimer_cancel(&rq
->hrtick_timer
);
389 * High-resolution timer tick.
390 * Runs from hardirq context with interrupts disabled.
392 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
394 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
396 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
398 raw_spin_lock(&rq
->lock
);
400 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
401 raw_spin_unlock(&rq
->lock
);
403 return HRTIMER_NORESTART
;
408 * called from hardirq (IPI) context
410 static void __hrtick_start(void *arg
)
414 raw_spin_lock(&rq
->lock
);
415 hrtimer_restart(&rq
->hrtick_timer
);
416 rq
->hrtick_csd_pending
= 0;
417 raw_spin_unlock(&rq
->lock
);
421 * Called to set the hrtick timer state.
423 * called with rq->lock held and irqs disabled
425 void hrtick_start(struct rq
*rq
, u64 delay
)
427 struct hrtimer
*timer
= &rq
->hrtick_timer
;
428 ktime_t time
= ktime_add_ns(timer
->base
->get_time(), delay
);
430 hrtimer_set_expires(timer
, time
);
432 if (rq
== this_rq()) {
433 hrtimer_restart(timer
);
434 } else if (!rq
->hrtick_csd_pending
) {
435 __smp_call_function_single(cpu_of(rq
), &rq
->hrtick_csd
, 0);
436 rq
->hrtick_csd_pending
= 1;
441 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
443 int cpu
= (int)(long)hcpu
;
446 case CPU_UP_CANCELED
:
447 case CPU_UP_CANCELED_FROZEN
:
448 case CPU_DOWN_PREPARE
:
449 case CPU_DOWN_PREPARE_FROZEN
:
451 case CPU_DEAD_FROZEN
:
452 hrtick_clear(cpu_rq(cpu
));
459 static __init
void init_hrtick(void)
461 hotcpu_notifier(hotplug_hrtick
, 0);
465 * Called to set the hrtick timer state.
467 * called with rq->lock held and irqs disabled
469 void hrtick_start(struct rq
*rq
, u64 delay
)
471 __hrtimer_start_range_ns(&rq
->hrtick_timer
, ns_to_ktime(delay
), 0,
472 HRTIMER_MODE_REL_PINNED
, 0);
475 static inline void init_hrtick(void)
478 #endif /* CONFIG_SMP */
480 static void init_rq_hrtick(struct rq
*rq
)
483 rq
->hrtick_csd_pending
= 0;
485 rq
->hrtick_csd
.flags
= 0;
486 rq
->hrtick_csd
.func
= __hrtick_start
;
487 rq
->hrtick_csd
.info
= rq
;
490 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
491 rq
->hrtick_timer
.function
= hrtick
;
493 #else /* CONFIG_SCHED_HRTICK */
494 static inline void hrtick_clear(struct rq
*rq
)
498 static inline void init_rq_hrtick(struct rq
*rq
)
502 static inline void init_hrtick(void)
505 #endif /* CONFIG_SCHED_HRTICK */
508 * resched_task - mark a task 'to be rescheduled now'.
510 * On UP this means the setting of the need_resched flag, on SMP it
511 * might also involve a cross-CPU call to trigger the scheduler on
515 void resched_task(struct task_struct
*p
)
519 assert_raw_spin_locked(&task_rq(p
)->lock
);
521 if (test_tsk_need_resched(p
))
524 set_tsk_need_resched(p
);
527 if (cpu
== smp_processor_id())
530 /* NEED_RESCHED must be visible before we test polling */
532 if (!tsk_is_polling(p
))
533 smp_send_reschedule(cpu
);
536 void resched_cpu(int cpu
)
538 struct rq
*rq
= cpu_rq(cpu
);
541 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
543 resched_task(cpu_curr(cpu
));
544 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
549 * In the semi idle case, use the nearest busy cpu for migrating timers
550 * from an idle cpu. This is good for power-savings.
552 * We don't do similar optimization for completely idle system, as
553 * selecting an idle cpu will add more delays to the timers than intended
554 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
556 int get_nohz_timer_target(void)
558 int cpu
= smp_processor_id();
560 struct sched_domain
*sd
;
563 for_each_domain(cpu
, sd
) {
564 for_each_cpu(i
, sched_domain_span(sd
)) {
576 * When add_timer_on() enqueues a timer into the timer wheel of an
577 * idle CPU then this timer might expire before the next timer event
578 * which is scheduled to wake up that CPU. In case of a completely
579 * idle system the next event might even be infinite time into the
580 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
581 * leaves the inner idle loop so the newly added timer is taken into
582 * account when the CPU goes back to idle and evaluates the timer
583 * wheel for the next timer event.
585 void wake_up_idle_cpu(int cpu
)
587 struct rq
*rq
= cpu_rq(cpu
);
589 if (cpu
== smp_processor_id())
593 * This is safe, as this function is called with the timer
594 * wheel base lock of (cpu) held. When the CPU is on the way
595 * to idle and has not yet set rq->curr to idle then it will
596 * be serialized on the timer wheel base lock and take the new
597 * timer into account automatically.
599 if (rq
->curr
!= rq
->idle
)
603 * We can set TIF_RESCHED on the idle task of the other CPU
604 * lockless. The worst case is that the other CPU runs the
605 * idle task through an additional NOOP schedule()
607 set_tsk_need_resched(rq
->idle
);
609 /* NEED_RESCHED must be visible before we test polling */
611 if (!tsk_is_polling(rq
->idle
))
612 smp_send_reschedule(cpu
);
615 static inline bool got_nohz_idle_kick(void)
617 int cpu
= smp_processor_id();
618 return idle_cpu(cpu
) && test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
621 #else /* CONFIG_NO_HZ */
623 static inline bool got_nohz_idle_kick(void)
628 #endif /* CONFIG_NO_HZ */
630 void sched_avg_update(struct rq
*rq
)
632 s64 period
= sched_avg_period();
634 while ((s64
)(rq
->clock
- rq
->age_stamp
) > period
) {
636 * Inline assembly required to prevent the compiler
637 * optimising this loop into a divmod call.
638 * See __iter_div_u64_rem() for another example of this.
640 asm("" : "+rm" (rq
->age_stamp
));
641 rq
->age_stamp
+= period
;
646 #else /* !CONFIG_SMP */
647 void resched_task(struct task_struct
*p
)
649 assert_raw_spin_locked(&task_rq(p
)->lock
);
650 set_tsk_need_resched(p
);
652 #endif /* CONFIG_SMP */
654 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
655 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
657 * Iterate task_group tree rooted at *from, calling @down when first entering a
658 * node and @up when leaving it for the final time.
660 * Caller must hold rcu_lock or sufficient equivalent.
662 int walk_tg_tree_from(struct task_group
*from
,
663 tg_visitor down
, tg_visitor up
, void *data
)
665 struct task_group
*parent
, *child
;
671 ret
= (*down
)(parent
, data
);
674 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
681 ret
= (*up
)(parent
, data
);
682 if (ret
|| parent
== from
)
686 parent
= parent
->parent
;
693 int tg_nop(struct task_group
*tg
, void *data
)
699 static void set_load_weight(struct task_struct
*p
)
701 int prio
= p
->static_prio
- MAX_RT_PRIO
;
702 struct load_weight
*load
= &p
->se
.load
;
705 * SCHED_IDLE tasks get minimal weight:
707 if (p
->policy
== SCHED_IDLE
) {
708 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
709 load
->inv_weight
= WMULT_IDLEPRIO
;
713 load
->weight
= scale_load(prio_to_weight
[prio
]);
714 load
->inv_weight
= prio_to_wmult
[prio
];
717 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
720 sched_info_queued(p
);
721 p
->sched_class
->enqueue_task(rq
, p
, flags
);
724 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
727 sched_info_dequeued(p
);
728 p
->sched_class
->dequeue_task(rq
, p
, flags
);
731 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
733 if (task_contributes_to_load(p
))
734 rq
->nr_uninterruptible
--;
736 enqueue_task(rq
, p
, flags
);
739 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
741 if (task_contributes_to_load(p
))
742 rq
->nr_uninterruptible
++;
744 dequeue_task(rq
, p
, flags
);
747 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
750 * In theory, the compile should just see 0 here, and optimize out the call
751 * to sched_rt_avg_update. But I don't trust it...
753 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
754 s64 steal
= 0, irq_delta
= 0;
756 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
757 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
760 * Since irq_time is only updated on {soft,}irq_exit, we might run into
761 * this case when a previous update_rq_clock() happened inside a
764 * When this happens, we stop ->clock_task and only update the
765 * prev_irq_time stamp to account for the part that fit, so that a next
766 * update will consume the rest. This ensures ->clock_task is
769 * It does however cause some slight miss-attribution of {soft,}irq
770 * time, a more accurate solution would be to update the irq_time using
771 * the current rq->clock timestamp, except that would require using
774 if (irq_delta
> delta
)
777 rq
->prev_irq_time
+= irq_delta
;
780 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
781 if (static_key_false((¶virt_steal_rq_enabled
))) {
784 steal
= paravirt_steal_clock(cpu_of(rq
));
785 steal
-= rq
->prev_steal_time_rq
;
787 if (unlikely(steal
> delta
))
790 st
= steal_ticks(steal
);
791 steal
= st
* TICK_NSEC
;
793 rq
->prev_steal_time_rq
+= steal
;
799 rq
->clock_task
+= delta
;
801 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
802 if ((irq_delta
+ steal
) && sched_feat(NONTASK_POWER
))
803 sched_rt_avg_update(rq
, irq_delta
+ steal
);
807 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
809 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
810 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
814 * Make it appear like a SCHED_FIFO task, its something
815 * userspace knows about and won't get confused about.
817 * Also, it will make PI more or less work without too
818 * much confusion -- but then, stop work should not
819 * rely on PI working anyway.
821 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
823 stop
->sched_class
= &stop_sched_class
;
826 cpu_rq(cpu
)->stop
= stop
;
830 * Reset it back to a normal scheduling class so that
831 * it can die in pieces.
833 old_stop
->sched_class
= &rt_sched_class
;
838 * __normal_prio - return the priority that is based on the static prio
840 static inline int __normal_prio(struct task_struct
*p
)
842 return p
->static_prio
;
846 * Calculate the expected normal priority: i.e. priority
847 * without taking RT-inheritance into account. Might be
848 * boosted by interactivity modifiers. Changes upon fork,
849 * setprio syscalls, and whenever the interactivity
850 * estimator recalculates.
852 static inline int normal_prio(struct task_struct
*p
)
856 if (task_has_rt_policy(p
))
857 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
859 prio
= __normal_prio(p
);
864 * Calculate the current priority, i.e. the priority
865 * taken into account by the scheduler. This value might
866 * be boosted by RT tasks, or might be boosted by
867 * interactivity modifiers. Will be RT if the task got
868 * RT-boosted. If not then it returns p->normal_prio.
870 static int effective_prio(struct task_struct
*p
)
872 p
->normal_prio
= normal_prio(p
);
874 * If we are RT tasks or we were boosted to RT priority,
875 * keep the priority unchanged. Otherwise, update priority
876 * to the normal priority:
878 if (!rt_prio(p
->prio
))
879 return p
->normal_prio
;
884 * task_curr - is this task currently executing on a CPU?
885 * @p: the task in question.
887 inline int task_curr(const struct task_struct
*p
)
889 return cpu_curr(task_cpu(p
)) == p
;
892 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
893 const struct sched_class
*prev_class
,
896 if (prev_class
!= p
->sched_class
) {
897 if (prev_class
->switched_from
)
898 prev_class
->switched_from(rq
, p
);
899 p
->sched_class
->switched_to(rq
, p
);
900 } else if (oldprio
!= p
->prio
)
901 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
904 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
906 const struct sched_class
*class;
908 if (p
->sched_class
== rq
->curr
->sched_class
) {
909 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
911 for_each_class(class) {
912 if (class == rq
->curr
->sched_class
)
914 if (class == p
->sched_class
) {
915 resched_task(rq
->curr
);
922 * A queue event has occurred, and we're going to schedule. In
923 * this case, we can save a useless back to back clock update.
925 if (rq
->curr
->on_rq
&& test_tsk_need_resched(rq
->curr
))
926 rq
->skip_clock_update
= 1;
929 static ATOMIC_NOTIFIER_HEAD(task_migration_notifier
);
931 void register_task_migration_notifier(struct notifier_block
*n
)
933 atomic_notifier_chain_register(&task_migration_notifier
, n
);
937 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
939 #ifdef CONFIG_SCHED_DEBUG
941 * We should never call set_task_cpu() on a blocked task,
942 * ttwu() will sort out the placement.
944 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
945 !(task_thread_info(p
)->preempt_count
& PREEMPT_ACTIVE
));
947 #ifdef CONFIG_LOCKDEP
949 * The caller should hold either p->pi_lock or rq->lock, when changing
950 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
952 * sched_move_task() holds both and thus holding either pins the cgroup,
955 * Furthermore, all task_rq users should acquire both locks, see
958 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
959 lockdep_is_held(&task_rq(p
)->lock
)));
963 trace_sched_migrate_task(p
, new_cpu
);
965 if (task_cpu(p
) != new_cpu
) {
966 struct task_migration_notifier tmn
;
968 if (p
->sched_class
->migrate_task_rq
)
969 p
->sched_class
->migrate_task_rq(p
, new_cpu
);
970 p
->se
.nr_migrations
++;
971 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, NULL
, 0);
974 tmn
.from_cpu
= task_cpu(p
);
975 tmn
.to_cpu
= new_cpu
;
977 atomic_notifier_call_chain(&task_migration_notifier
, 0, &tmn
);
980 __set_task_cpu(p
, new_cpu
);
983 struct migration_arg
{
984 struct task_struct
*task
;
988 static int migration_cpu_stop(void *data
);
991 * wait_task_inactive - wait for a thread to unschedule.
993 * If @match_state is nonzero, it's the @p->state value just checked and
994 * not expected to change. If it changes, i.e. @p might have woken up,
995 * then return zero. When we succeed in waiting for @p to be off its CPU,
996 * we return a positive number (its total switch count). If a second call
997 * a short while later returns the same number, the caller can be sure that
998 * @p has remained unscheduled the whole time.
1000 * The caller must ensure that the task *will* unschedule sometime soon,
1001 * else this function might spin for a *long* time. This function can't
1002 * be called with interrupts off, or it may introduce deadlock with
1003 * smp_call_function() if an IPI is sent by the same process we are
1004 * waiting to become inactive.
1006 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1008 unsigned long flags
;
1015 * We do the initial early heuristics without holding
1016 * any task-queue locks at all. We'll only try to get
1017 * the runqueue lock when things look like they will
1023 * If the task is actively running on another CPU
1024 * still, just relax and busy-wait without holding
1027 * NOTE! Since we don't hold any locks, it's not
1028 * even sure that "rq" stays as the right runqueue!
1029 * But we don't care, since "task_running()" will
1030 * return false if the runqueue has changed and p
1031 * is actually now running somewhere else!
1033 while (task_running(rq
, p
)) {
1034 if (match_state
&& unlikely(p
->state
!= match_state
))
1040 * Ok, time to look more closely! We need the rq
1041 * lock now, to be *sure*. If we're wrong, we'll
1042 * just go back and repeat.
1044 rq
= task_rq_lock(p
, &flags
);
1045 trace_sched_wait_task(p
);
1046 running
= task_running(rq
, p
);
1049 if (!match_state
|| p
->state
== match_state
)
1050 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1051 task_rq_unlock(rq
, p
, &flags
);
1054 * If it changed from the expected state, bail out now.
1056 if (unlikely(!ncsw
))
1060 * Was it really running after all now that we
1061 * checked with the proper locks actually held?
1063 * Oops. Go back and try again..
1065 if (unlikely(running
)) {
1071 * It's not enough that it's not actively running,
1072 * it must be off the runqueue _entirely_, and not
1075 * So if it was still runnable (but just not actively
1076 * running right now), it's preempted, and we should
1077 * yield - it could be a while.
1079 if (unlikely(on_rq
)) {
1080 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1082 set_current_state(TASK_UNINTERRUPTIBLE
);
1083 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1088 * Ahh, all good. It wasn't running, and it wasn't
1089 * runnable, which means that it will never become
1090 * running in the future either. We're all done!
1099 * kick_process - kick a running thread to enter/exit the kernel
1100 * @p: the to-be-kicked thread
1102 * Cause a process which is running on another CPU to enter
1103 * kernel-mode, without any delay. (to get signals handled.)
1105 * NOTE: this function doesn't have to take the runqueue lock,
1106 * because all it wants to ensure is that the remote task enters
1107 * the kernel. If the IPI races and the task has been migrated
1108 * to another CPU then no harm is done and the purpose has been
1111 void kick_process(struct task_struct
*p
)
1117 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1118 smp_send_reschedule(cpu
);
1121 EXPORT_SYMBOL_GPL(kick_process
);
1122 #endif /* CONFIG_SMP */
1126 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1128 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1130 int nid
= cpu_to_node(cpu
);
1131 const struct cpumask
*nodemask
= NULL
;
1132 enum { cpuset
, possible
, fail
} state
= cpuset
;
1136 * If the node that the cpu is on has been offlined, cpu_to_node()
1137 * will return -1. There is no cpu on the node, and we should
1138 * select the cpu on the other node.
1141 nodemask
= cpumask_of_node(nid
);
1143 /* Look for allowed, online CPU in same node. */
1144 for_each_cpu(dest_cpu
, nodemask
) {
1145 if (!cpu_online(dest_cpu
))
1147 if (!cpu_active(dest_cpu
))
1149 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1155 /* Any allowed, online CPU? */
1156 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1157 if (!cpu_online(dest_cpu
))
1159 if (!cpu_active(dest_cpu
))
1166 /* No more Mr. Nice Guy. */
1167 cpuset_cpus_allowed_fallback(p
);
1172 do_set_cpus_allowed(p
, cpu_possible_mask
);
1183 if (state
!= cpuset
) {
1185 * Don't tell them about moving exiting tasks or
1186 * kernel threads (both mm NULL), since they never
1189 if (p
->mm
&& printk_ratelimit()) {
1190 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1191 task_pid_nr(p
), p
->comm
, cpu
);
1199 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1202 int select_task_rq(struct task_struct
*p
, int sd_flags
, int wake_flags
)
1204 int cpu
= p
->sched_class
->select_task_rq(p
, sd_flags
, wake_flags
);
1207 * In order not to call set_task_cpu() on a blocking task we need
1208 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1211 * Since this is common to all placement strategies, this lives here.
1213 * [ this allows ->select_task() to simply return task_cpu(p) and
1214 * not worry about this generic constraint ]
1216 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1218 cpu
= select_fallback_rq(task_cpu(p
), p
);
1223 static void update_avg(u64
*avg
, u64 sample
)
1225 s64 diff
= sample
- *avg
;
1231 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1233 #ifdef CONFIG_SCHEDSTATS
1234 struct rq
*rq
= this_rq();
1237 int this_cpu
= smp_processor_id();
1239 if (cpu
== this_cpu
) {
1240 schedstat_inc(rq
, ttwu_local
);
1241 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1243 struct sched_domain
*sd
;
1245 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1247 for_each_domain(this_cpu
, sd
) {
1248 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1249 schedstat_inc(sd
, ttwu_wake_remote
);
1256 if (wake_flags
& WF_MIGRATED
)
1257 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1259 #endif /* CONFIG_SMP */
1261 schedstat_inc(rq
, ttwu_count
);
1262 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1264 if (wake_flags
& WF_SYNC
)
1265 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1267 #endif /* CONFIG_SCHEDSTATS */
1270 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1272 activate_task(rq
, p
, en_flags
);
1275 /* if a worker is waking up, notify workqueue */
1276 if (p
->flags
& PF_WQ_WORKER
)
1277 wq_worker_waking_up(p
, cpu_of(rq
));
1281 * Mark the task runnable and perform wakeup-preemption.
1284 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1286 check_preempt_curr(rq
, p
, wake_flags
);
1287 trace_sched_wakeup(p
, true);
1289 p
->state
= TASK_RUNNING
;
1291 if (p
->sched_class
->task_woken
)
1292 p
->sched_class
->task_woken(rq
, p
);
1294 if (rq
->idle_stamp
) {
1295 u64 delta
= rq
->clock
- rq
->idle_stamp
;
1296 u64 max
= 2*sysctl_sched_migration_cost
;
1301 update_avg(&rq
->avg_idle
, delta
);
1308 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1311 if (p
->sched_contributes_to_load
)
1312 rq
->nr_uninterruptible
--;
1315 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1316 ttwu_do_wakeup(rq
, p
, wake_flags
);
1320 * Called in case the task @p isn't fully descheduled from its runqueue,
1321 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1322 * since all we need to do is flip p->state to TASK_RUNNING, since
1323 * the task is still ->on_rq.
1325 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1330 rq
= __task_rq_lock(p
);
1332 ttwu_do_wakeup(rq
, p
, wake_flags
);
1335 __task_rq_unlock(rq
);
1341 static void sched_ttwu_pending(void)
1343 struct rq
*rq
= this_rq();
1344 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1345 struct task_struct
*p
;
1347 raw_spin_lock(&rq
->lock
);
1350 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1351 llist
= llist_next(llist
);
1352 ttwu_do_activate(rq
, p
, 0);
1355 raw_spin_unlock(&rq
->lock
);
1358 void scheduler_ipi(void)
1360 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick())
1364 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1365 * traditionally all their work was done from the interrupt return
1366 * path. Now that we actually do some work, we need to make sure
1369 * Some archs already do call them, luckily irq_enter/exit nest
1372 * Arguably we should visit all archs and update all handlers,
1373 * however a fair share of IPIs are still resched only so this would
1374 * somewhat pessimize the simple resched case.
1377 sched_ttwu_pending();
1380 * Check if someone kicked us for doing the nohz idle load balance.
1382 if (unlikely(got_nohz_idle_kick() && !need_resched())) {
1383 this_rq()->idle_balance
= 1;
1384 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1389 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1391 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
))
1392 smp_send_reschedule(cpu
);
1395 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1397 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1399 #endif /* CONFIG_SMP */
1401 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1403 struct rq
*rq
= cpu_rq(cpu
);
1405 #if defined(CONFIG_SMP)
1406 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1407 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1408 ttwu_queue_remote(p
, cpu
);
1413 raw_spin_lock(&rq
->lock
);
1414 ttwu_do_activate(rq
, p
, 0);
1415 raw_spin_unlock(&rq
->lock
);
1419 * try_to_wake_up - wake up a thread
1420 * @p: the thread to be awakened
1421 * @state: the mask of task states that can be woken
1422 * @wake_flags: wake modifier flags (WF_*)
1424 * Put it on the run-queue if it's not already there. The "current"
1425 * thread is always on the run-queue (except when the actual
1426 * re-schedule is in progress), and as such you're allowed to do
1427 * the simpler "current->state = TASK_RUNNING" to mark yourself
1428 * runnable without the overhead of this.
1430 * Returns %true if @p was woken up, %false if it was already running
1431 * or @state didn't match @p's state.
1434 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
1436 unsigned long flags
;
1437 int cpu
, success
= 0;
1440 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1441 if (!(p
->state
& state
))
1444 success
= 1; /* we're going to change ->state */
1447 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
1452 * If the owning (remote) cpu is still in the middle of schedule() with
1453 * this task as prev, wait until its done referencing the task.
1458 * Pairs with the smp_wmb() in finish_lock_switch().
1462 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
1463 p
->state
= TASK_WAKING
;
1465 if (p
->sched_class
->task_waking
)
1466 p
->sched_class
->task_waking(p
);
1468 cpu
= select_task_rq(p
, SD_BALANCE_WAKE
, wake_flags
);
1469 if (task_cpu(p
) != cpu
) {
1470 wake_flags
|= WF_MIGRATED
;
1471 set_task_cpu(p
, cpu
);
1473 #endif /* CONFIG_SMP */
1477 ttwu_stat(p
, cpu
, wake_flags
);
1479 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1485 * try_to_wake_up_local - try to wake up a local task with rq lock held
1486 * @p: the thread to be awakened
1488 * Put @p on the run-queue if it's not already there. The caller must
1489 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1492 static void try_to_wake_up_local(struct task_struct
*p
)
1494 struct rq
*rq
= task_rq(p
);
1496 if (WARN_ON_ONCE(rq
!= this_rq()) ||
1497 WARN_ON_ONCE(p
== current
))
1500 lockdep_assert_held(&rq
->lock
);
1502 if (!raw_spin_trylock(&p
->pi_lock
)) {
1503 raw_spin_unlock(&rq
->lock
);
1504 raw_spin_lock(&p
->pi_lock
);
1505 raw_spin_lock(&rq
->lock
);
1508 if (!(p
->state
& TASK_NORMAL
))
1512 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
1514 ttwu_do_wakeup(rq
, p
, 0);
1515 ttwu_stat(p
, smp_processor_id(), 0);
1517 raw_spin_unlock(&p
->pi_lock
);
1521 * wake_up_process - Wake up a specific process
1522 * @p: The process to be woken up.
1524 * Attempt to wake up the nominated process and move it to the set of runnable
1525 * processes. Returns 1 if the process was woken up, 0 if it was already
1528 * It may be assumed that this function implies a write memory barrier before
1529 * changing the task state if and only if any tasks are woken up.
1531 int wake_up_process(struct task_struct
*p
)
1533 WARN_ON(task_is_stopped_or_traced(p
));
1534 return try_to_wake_up(p
, TASK_NORMAL
, 0);
1536 EXPORT_SYMBOL(wake_up_process
);
1538 int wake_up_state(struct task_struct
*p
, unsigned int state
)
1540 return try_to_wake_up(p
, state
, 0);
1544 * Perform scheduler related setup for a newly forked process p.
1545 * p is forked by current.
1547 * __sched_fork() is basic setup used by init_idle() too:
1549 static void __sched_fork(struct task_struct
*p
)
1554 p
->se
.exec_start
= 0;
1555 p
->se
.sum_exec_runtime
= 0;
1556 p
->se
.prev_sum_exec_runtime
= 0;
1557 p
->se
.nr_migrations
= 0;
1559 INIT_LIST_HEAD(&p
->se
.group_node
);
1562 * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
1563 * removed when useful for applications beyond shares distribution (e.g.
1566 #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
1567 p
->se
.avg
.runnable_avg_period
= 0;
1568 p
->se
.avg
.runnable_avg_sum
= 0;
1570 #ifdef CONFIG_SCHEDSTATS
1571 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
1574 INIT_LIST_HEAD(&p
->rt
.run_list
);
1576 #ifdef CONFIG_PREEMPT_NOTIFIERS
1577 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1580 #ifdef CONFIG_NUMA_BALANCING
1581 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
1582 p
->mm
->numa_next_scan
= jiffies
;
1583 p
->mm
->numa_next_reset
= jiffies
;
1584 p
->mm
->numa_scan_seq
= 0;
1587 p
->node_stamp
= 0ULL;
1588 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
1589 p
->numa_migrate_seq
= p
->mm
? p
->mm
->numa_scan_seq
- 1 : 0;
1590 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
1591 p
->numa_work
.next
= &p
->numa_work
;
1592 #endif /* CONFIG_NUMA_BALANCING */
1595 #ifdef CONFIG_NUMA_BALANCING
1596 #ifdef CONFIG_SCHED_DEBUG
1597 void set_numabalancing_state(bool enabled
)
1600 sched_feat_set("NUMA");
1602 sched_feat_set("NO_NUMA");
1605 __read_mostly
bool numabalancing_enabled
;
1607 void set_numabalancing_state(bool enabled
)
1609 numabalancing_enabled
= enabled
;
1611 #endif /* CONFIG_SCHED_DEBUG */
1612 #endif /* CONFIG_NUMA_BALANCING */
1615 * fork()/clone()-time setup:
1617 void sched_fork(struct task_struct
*p
)
1619 unsigned long flags
;
1620 int cpu
= get_cpu();
1624 * We mark the process as running here. This guarantees that
1625 * nobody will actually run it, and a signal or other external
1626 * event cannot wake it up and insert it on the runqueue either.
1628 p
->state
= TASK_RUNNING
;
1631 * Make sure we do not leak PI boosting priority to the child.
1633 p
->prio
= current
->normal_prio
;
1636 * Revert to default priority/policy on fork if requested.
1638 if (unlikely(p
->sched_reset_on_fork
)) {
1639 if (task_has_rt_policy(p
)) {
1640 p
->policy
= SCHED_NORMAL
;
1641 p
->static_prio
= NICE_TO_PRIO(0);
1643 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
1644 p
->static_prio
= NICE_TO_PRIO(0);
1646 p
->prio
= p
->normal_prio
= __normal_prio(p
);
1650 * We don't need the reset flag anymore after the fork. It has
1651 * fulfilled its duty:
1653 p
->sched_reset_on_fork
= 0;
1656 if (!rt_prio(p
->prio
))
1657 p
->sched_class
= &fair_sched_class
;
1659 if (p
->sched_class
->task_fork
)
1660 p
->sched_class
->task_fork(p
);
1663 * The child is not yet in the pid-hash so no cgroup attach races,
1664 * and the cgroup is pinned to this child due to cgroup_fork()
1665 * is ran before sched_fork().
1667 * Silence PROVE_RCU.
1669 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1670 set_task_cpu(p
, cpu
);
1671 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1673 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1674 if (likely(sched_info_on()))
1675 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1677 #if defined(CONFIG_SMP)
1680 #ifdef CONFIG_PREEMPT_COUNT
1681 /* Want to start with kernel preemption disabled. */
1682 task_thread_info(p
)->preempt_count
= 1;
1685 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
1692 * wake_up_new_task - wake up a newly created task for the first time.
1694 * This function will do some initial scheduler statistics housekeeping
1695 * that must be done for every newly created context, then puts the task
1696 * on the runqueue and wakes it.
1698 void wake_up_new_task(struct task_struct
*p
)
1700 unsigned long flags
;
1703 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1706 * Fork balancing, do it here and not earlier because:
1707 * - cpus_allowed can change in the fork path
1708 * - any previously selected cpu might disappear through hotplug
1710 set_task_cpu(p
, select_task_rq(p
, SD_BALANCE_FORK
, 0));
1713 rq
= __task_rq_lock(p
);
1714 activate_task(rq
, p
, 0);
1716 trace_sched_wakeup_new(p
, true);
1717 check_preempt_curr(rq
, p
, WF_FORK
);
1719 if (p
->sched_class
->task_woken
)
1720 p
->sched_class
->task_woken(rq
, p
);
1722 task_rq_unlock(rq
, p
, &flags
);
1725 #ifdef CONFIG_PREEMPT_NOTIFIERS
1728 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1729 * @notifier: notifier struct to register
1731 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1733 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1735 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1738 * preempt_notifier_unregister - no longer interested in preemption notifications
1739 * @notifier: notifier struct to unregister
1741 * This is safe to call from within a preemption notifier.
1743 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1745 hlist_del(¬ifier
->link
);
1747 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1749 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1751 struct preempt_notifier
*notifier
;
1753 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1754 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1758 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1759 struct task_struct
*next
)
1761 struct preempt_notifier
*notifier
;
1763 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1764 notifier
->ops
->sched_out(notifier
, next
);
1767 #else /* !CONFIG_PREEMPT_NOTIFIERS */
1769 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1774 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1775 struct task_struct
*next
)
1779 #endif /* CONFIG_PREEMPT_NOTIFIERS */
1782 * prepare_task_switch - prepare to switch tasks
1783 * @rq: the runqueue preparing to switch
1784 * @prev: the current task that is being switched out
1785 * @next: the task we are going to switch to.
1787 * This is called with the rq lock held and interrupts off. It must
1788 * be paired with a subsequent finish_task_switch after the context
1791 * prepare_task_switch sets up locking and calls architecture specific
1795 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1796 struct task_struct
*next
)
1798 trace_sched_switch(prev
, next
);
1799 sched_info_switch(prev
, next
);
1800 perf_event_task_sched_out(prev
, next
);
1801 fire_sched_out_preempt_notifiers(prev
, next
);
1802 prepare_lock_switch(rq
, next
);
1803 prepare_arch_switch(next
);
1807 * finish_task_switch - clean up after a task-switch
1808 * @rq: runqueue associated with task-switch
1809 * @prev: the thread we just switched away from.
1811 * finish_task_switch must be called after the context switch, paired
1812 * with a prepare_task_switch call before the context switch.
1813 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1814 * and do any other architecture-specific cleanup actions.
1816 * Note that we may have delayed dropping an mm in context_switch(). If
1817 * so, we finish that here outside of the runqueue lock. (Doing it
1818 * with the lock held can cause deadlocks; see schedule() for
1821 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1822 __releases(rq
->lock
)
1824 struct mm_struct
*mm
= rq
->prev_mm
;
1830 * A task struct has one reference for the use as "current".
1831 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1832 * schedule one last time. The schedule call will never return, and
1833 * the scheduled task must drop that reference.
1834 * The test for TASK_DEAD must occur while the runqueue locks are
1835 * still held, otherwise prev could be scheduled on another cpu, die
1836 * there before we look at prev->state, and then the reference would
1838 * Manfred Spraul <manfred@colorfullife.com>
1840 prev_state
= prev
->state
;
1841 vtime_task_switch(prev
);
1842 finish_arch_switch(prev
);
1843 perf_event_task_sched_in(prev
, current
);
1844 finish_lock_switch(rq
, prev
);
1845 finish_arch_post_lock_switch();
1847 fire_sched_in_preempt_notifiers(current
);
1850 if (unlikely(prev_state
== TASK_DEAD
)) {
1852 * Remove function-return probe instances associated with this
1853 * task and put them back on the free list.
1855 kprobe_flush_task(prev
);
1856 put_task_struct(prev
);
1862 /* assumes rq->lock is held */
1863 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*prev
)
1865 if (prev
->sched_class
->pre_schedule
)
1866 prev
->sched_class
->pre_schedule(rq
, prev
);
1869 /* rq->lock is NOT held, but preemption is disabled */
1870 static inline void post_schedule(struct rq
*rq
)
1872 if (rq
->post_schedule
) {
1873 unsigned long flags
;
1875 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1876 if (rq
->curr
->sched_class
->post_schedule
)
1877 rq
->curr
->sched_class
->post_schedule(rq
);
1878 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1880 rq
->post_schedule
= 0;
1886 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*p
)
1890 static inline void post_schedule(struct rq
*rq
)
1897 * schedule_tail - first thing a freshly forked thread must call.
1898 * @prev: the thread we just switched away from.
1900 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1901 __releases(rq
->lock
)
1903 struct rq
*rq
= this_rq();
1905 finish_task_switch(rq
, prev
);
1908 * FIXME: do we need to worry about rq being invalidated by the
1913 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1914 /* In this case, finish_task_switch does not reenable preemption */
1917 if (current
->set_child_tid
)
1918 put_user(task_pid_vnr(current
), current
->set_child_tid
);
1922 * context_switch - switch to the new MM and the new
1923 * thread's register state.
1926 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1927 struct task_struct
*next
)
1929 struct mm_struct
*mm
, *oldmm
;
1931 prepare_task_switch(rq
, prev
, next
);
1934 oldmm
= prev
->active_mm
;
1936 * For paravirt, this is coupled with an exit in switch_to to
1937 * combine the page table reload and the switch backend into
1940 arch_start_context_switch(prev
);
1943 next
->active_mm
= oldmm
;
1944 atomic_inc(&oldmm
->mm_count
);
1945 enter_lazy_tlb(oldmm
, next
);
1947 switch_mm(oldmm
, mm
, next
);
1950 prev
->active_mm
= NULL
;
1951 rq
->prev_mm
= oldmm
;
1954 * Since the runqueue lock will be released by the next
1955 * task (which is an invalid locking op but in the case
1956 * of the scheduler it's an obvious special-case), so we
1957 * do an early lockdep release here:
1959 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1960 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1963 context_tracking_task_switch(prev
, next
);
1964 /* Here we just switch the register state and the stack. */
1965 switch_to(prev
, next
, prev
);
1969 * this_rq must be evaluated again because prev may have moved
1970 * CPUs since it called schedule(), thus the 'rq' on its stack
1971 * frame will be invalid.
1973 finish_task_switch(this_rq(), prev
);
1977 * nr_running and nr_context_switches:
1979 * externally visible scheduler statistics: current number of runnable
1980 * threads, total number of context switches performed since bootup.
1982 unsigned long nr_running(void)
1984 unsigned long i
, sum
= 0;
1986 for_each_online_cpu(i
)
1987 sum
+= cpu_rq(i
)->nr_running
;
1992 unsigned long long nr_context_switches(void)
1995 unsigned long long sum
= 0;
1997 for_each_possible_cpu(i
)
1998 sum
+= cpu_rq(i
)->nr_switches
;
2003 unsigned long nr_iowait(void)
2005 unsigned long i
, sum
= 0;
2007 for_each_possible_cpu(i
)
2008 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2013 unsigned long nr_iowait_cpu(int cpu
)
2015 struct rq
*this = cpu_rq(cpu
);
2016 return atomic_read(&this->nr_iowait
);
2019 unsigned long this_cpu_load(void)
2021 struct rq
*this = this_rq();
2022 return this->cpu_load
[0];
2027 * Global load-average calculations
2029 * We take a distributed and async approach to calculating the global load-avg
2030 * in order to minimize overhead.
2032 * The global load average is an exponentially decaying average of nr_running +
2033 * nr_uninterruptible.
2035 * Once every LOAD_FREQ:
2038 * for_each_possible_cpu(cpu)
2039 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible;
2041 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n)
2043 * Due to a number of reasons the above turns in the mess below:
2045 * - for_each_possible_cpu() is prohibitively expensive on machines with
2046 * serious number of cpus, therefore we need to take a distributed approach
2047 * to calculating nr_active.
2049 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0
2050 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) }
2052 * So assuming nr_active := 0 when we start out -- true per definition, we
2053 * can simply take per-cpu deltas and fold those into a global accumulate
2054 * to obtain the same result. See calc_load_fold_active().
2056 * Furthermore, in order to avoid synchronizing all per-cpu delta folding
2057 * across the machine, we assume 10 ticks is sufficient time for every
2058 * cpu to have completed this task.
2060 * This places an upper-bound on the IRQ-off latency of the machine. Then
2061 * again, being late doesn't loose the delta, just wrecks the sample.
2063 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because
2064 * this would add another cross-cpu cacheline miss and atomic operation
2065 * to the wakeup path. Instead we increment on whatever cpu the task ran
2066 * when it went into uninterruptible state and decrement on whatever cpu
2067 * did the wakeup. This means that only the sum of nr_uninterruptible over
2068 * all cpus yields the correct result.
2070 * This covers the NO_HZ=n code, for extra head-aches, see the comment below.
2073 /* Variables and functions for calc_load */
2074 static atomic_long_t calc_load_tasks
;
2075 static unsigned long calc_load_update
;
2076 unsigned long avenrun
[3];
2077 EXPORT_SYMBOL(avenrun
); /* should be removed */
2080 * get_avenrun - get the load average array
2081 * @loads: pointer to dest load array
2082 * @offset: offset to add
2083 * @shift: shift count to shift the result left
2085 * These values are estimates at best, so no need for locking.
2087 void get_avenrun(unsigned long *loads
, unsigned long offset
, int shift
)
2089 loads
[0] = (avenrun
[0] + offset
) << shift
;
2090 loads
[1] = (avenrun
[1] + offset
) << shift
;
2091 loads
[2] = (avenrun
[2] + offset
) << shift
;
2094 static long calc_load_fold_active(struct rq
*this_rq
)
2096 long nr_active
, delta
= 0;
2098 nr_active
= this_rq
->nr_running
;
2099 nr_active
+= (long) this_rq
->nr_uninterruptible
;
2101 if (nr_active
!= this_rq
->calc_load_active
) {
2102 delta
= nr_active
- this_rq
->calc_load_active
;
2103 this_rq
->calc_load_active
= nr_active
;
2110 * a1 = a0 * e + a * (1 - e)
2112 static unsigned long
2113 calc_load(unsigned long load
, unsigned long exp
, unsigned long active
)
2116 load
+= active
* (FIXED_1
- exp
);
2117 load
+= 1UL << (FSHIFT
- 1);
2118 return load
>> FSHIFT
;
2123 * Handle NO_HZ for the global load-average.
2125 * Since the above described distributed algorithm to compute the global
2126 * load-average relies on per-cpu sampling from the tick, it is affected by
2129 * The basic idea is to fold the nr_active delta into a global idle-delta upon
2130 * entering NO_HZ state such that we can include this as an 'extra' cpu delta
2131 * when we read the global state.
2133 * Obviously reality has to ruin such a delightfully simple scheme:
2135 * - When we go NO_HZ idle during the window, we can negate our sample
2136 * contribution, causing under-accounting.
2138 * We avoid this by keeping two idle-delta counters and flipping them
2139 * when the window starts, thus separating old and new NO_HZ load.
2141 * The only trick is the slight shift in index flip for read vs write.
2145 * |-|-----------|-|-----------|-|-----------|-|
2146 * r:0 0 1 1 0 0 1 1 0
2147 * w:0 1 1 0 0 1 1 0 0
2149 * This ensures we'll fold the old idle contribution in this window while
2150 * accumlating the new one.
2152 * - When we wake up from NO_HZ idle during the window, we push up our
2153 * contribution, since we effectively move our sample point to a known
2156 * This is solved by pushing the window forward, and thus skipping the
2157 * sample, for this cpu (effectively using the idle-delta for this cpu which
2158 * was in effect at the time the window opened). This also solves the issue
2159 * of having to deal with a cpu having been in NOHZ idle for multiple
2160 * LOAD_FREQ intervals.
2162 * When making the ILB scale, we should try to pull this in as well.
2164 static atomic_long_t calc_load_idle
[2];
2165 static int calc_load_idx
;
2167 static inline int calc_load_write_idx(void)
2169 int idx
= calc_load_idx
;
2172 * See calc_global_nohz(), if we observe the new index, we also
2173 * need to observe the new update time.
2178 * If the folding window started, make sure we start writing in the
2181 if (!time_before(jiffies
, calc_load_update
))
2187 static inline int calc_load_read_idx(void)
2189 return calc_load_idx
& 1;
2192 void calc_load_enter_idle(void)
2194 struct rq
*this_rq
= this_rq();
2198 * We're going into NOHZ mode, if there's any pending delta, fold it
2199 * into the pending idle delta.
2201 delta
= calc_load_fold_active(this_rq
);
2203 int idx
= calc_load_write_idx();
2204 atomic_long_add(delta
, &calc_load_idle
[idx
]);
2208 void calc_load_exit_idle(void)
2210 struct rq
*this_rq
= this_rq();
2213 * If we're still before the sample window, we're done.
2215 if (time_before(jiffies
, this_rq
->calc_load_update
))
2219 * We woke inside or after the sample window, this means we're already
2220 * accounted through the nohz accounting, so skip the entire deal and
2221 * sync up for the next window.
2223 this_rq
->calc_load_update
= calc_load_update
;
2224 if (time_before(jiffies
, this_rq
->calc_load_update
+ 10))
2225 this_rq
->calc_load_update
+= LOAD_FREQ
;
2228 static long calc_load_fold_idle(void)
2230 int idx
= calc_load_read_idx();
2233 if (atomic_long_read(&calc_load_idle
[idx
]))
2234 delta
= atomic_long_xchg(&calc_load_idle
[idx
], 0);
2240 * fixed_power_int - compute: x^n, in O(log n) time
2242 * @x: base of the power
2243 * @frac_bits: fractional bits of @x
2244 * @n: power to raise @x to.
2246 * By exploiting the relation between the definition of the natural power
2247 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
2248 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
2249 * (where: n_i \elem {0, 1}, the binary vector representing n),
2250 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
2251 * of course trivially computable in O(log_2 n), the length of our binary
2254 static unsigned long
2255 fixed_power_int(unsigned long x
, unsigned int frac_bits
, unsigned int n
)
2257 unsigned long result
= 1UL << frac_bits
;
2262 result
+= 1UL << (frac_bits
- 1);
2263 result
>>= frac_bits
;
2269 x
+= 1UL << (frac_bits
- 1);
2277 * a1 = a0 * e + a * (1 - e)
2279 * a2 = a1 * e + a * (1 - e)
2280 * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
2281 * = a0 * e^2 + a * (1 - e) * (1 + e)
2283 * a3 = a2 * e + a * (1 - e)
2284 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
2285 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
2289 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
2290 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
2291 * = a0 * e^n + a * (1 - e^n)
2293 * [1] application of the geometric series:
2296 * S_n := \Sum x^i = -------------
2299 static unsigned long
2300 calc_load_n(unsigned long load
, unsigned long exp
,
2301 unsigned long active
, unsigned int n
)
2304 return calc_load(load
, fixed_power_int(exp
, FSHIFT
, n
), active
);
2308 * NO_HZ can leave us missing all per-cpu ticks calling
2309 * calc_load_account_active(), but since an idle CPU folds its delta into
2310 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
2311 * in the pending idle delta if our idle period crossed a load cycle boundary.
2313 * Once we've updated the global active value, we need to apply the exponential
2314 * weights adjusted to the number of cycles missed.
2316 static void calc_global_nohz(void)
2318 long delta
, active
, n
;
2320 if (!time_before(jiffies
, calc_load_update
+ 10)) {
2322 * Catch-up, fold however many we are behind still
2324 delta
= jiffies
- calc_load_update
- 10;
2325 n
= 1 + (delta
/ LOAD_FREQ
);
2327 active
= atomic_long_read(&calc_load_tasks
);
2328 active
= active
> 0 ? active
* FIXED_1
: 0;
2330 avenrun
[0] = calc_load_n(avenrun
[0], EXP_1
, active
, n
);
2331 avenrun
[1] = calc_load_n(avenrun
[1], EXP_5
, active
, n
);
2332 avenrun
[2] = calc_load_n(avenrun
[2], EXP_15
, active
, n
);
2334 calc_load_update
+= n
* LOAD_FREQ
;
2338 * Flip the idle index...
2340 * Make sure we first write the new time then flip the index, so that
2341 * calc_load_write_idx() will see the new time when it reads the new
2342 * index, this avoids a double flip messing things up.
2347 #else /* !CONFIG_NO_HZ */
2349 static inline long calc_load_fold_idle(void) { return 0; }
2350 static inline void calc_global_nohz(void) { }
2352 #endif /* CONFIG_NO_HZ */
2355 * calc_load - update the avenrun load estimates 10 ticks after the
2356 * CPUs have updated calc_load_tasks.
2358 void calc_global_load(unsigned long ticks
)
2362 if (time_before(jiffies
, calc_load_update
+ 10))
2366 * Fold the 'old' idle-delta to include all NO_HZ cpus.
2368 delta
= calc_load_fold_idle();
2370 atomic_long_add(delta
, &calc_load_tasks
);
2372 active
= atomic_long_read(&calc_load_tasks
);
2373 active
= active
> 0 ? active
* FIXED_1
: 0;
2375 avenrun
[0] = calc_load(avenrun
[0], EXP_1
, active
);
2376 avenrun
[1] = calc_load(avenrun
[1], EXP_5
, active
);
2377 avenrun
[2] = calc_load(avenrun
[2], EXP_15
, active
);
2379 calc_load_update
+= LOAD_FREQ
;
2382 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk.
2388 * Called from update_cpu_load() to periodically update this CPU's
2391 static void calc_load_account_active(struct rq
*this_rq
)
2395 if (time_before(jiffies
, this_rq
->calc_load_update
))
2398 delta
= calc_load_fold_active(this_rq
);
2400 atomic_long_add(delta
, &calc_load_tasks
);
2402 this_rq
->calc_load_update
+= LOAD_FREQ
;
2406 * End of global load-average stuff
2410 * The exact cpuload at various idx values, calculated at every tick would be
2411 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
2413 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
2414 * on nth tick when cpu may be busy, then we have:
2415 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2416 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
2418 * decay_load_missed() below does efficient calculation of
2419 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2420 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
2422 * The calculation is approximated on a 128 point scale.
2423 * degrade_zero_ticks is the number of ticks after which load at any
2424 * particular idx is approximated to be zero.
2425 * degrade_factor is a precomputed table, a row for each load idx.
2426 * Each column corresponds to degradation factor for a power of two ticks,
2427 * based on 128 point scale.
2429 * row 2, col 3 (=12) says that the degradation at load idx 2 after
2430 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
2432 * With this power of 2 load factors, we can degrade the load n times
2433 * by looking at 1 bits in n and doing as many mult/shift instead of
2434 * n mult/shifts needed by the exact degradation.
2436 #define DEGRADE_SHIFT 7
2437 static const unsigned char
2438 degrade_zero_ticks
[CPU_LOAD_IDX_MAX
] = {0, 8, 32, 64, 128};
2439 static const unsigned char
2440 degrade_factor
[CPU_LOAD_IDX_MAX
][DEGRADE_SHIFT
+ 1] = {
2441 {0, 0, 0, 0, 0, 0, 0, 0},
2442 {64, 32, 8, 0, 0, 0, 0, 0},
2443 {96, 72, 40, 12, 1, 0, 0},
2444 {112, 98, 75, 43, 15, 1, 0},
2445 {120, 112, 98, 76, 45, 16, 2} };
2448 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
2449 * would be when CPU is idle and so we just decay the old load without
2450 * adding any new load.
2452 static unsigned long
2453 decay_load_missed(unsigned long load
, unsigned long missed_updates
, int idx
)
2457 if (!missed_updates
)
2460 if (missed_updates
>= degrade_zero_ticks
[idx
])
2464 return load
>> missed_updates
;
2466 while (missed_updates
) {
2467 if (missed_updates
% 2)
2468 load
= (load
* degrade_factor
[idx
][j
]) >> DEGRADE_SHIFT
;
2470 missed_updates
>>= 1;
2477 * Update rq->cpu_load[] statistics. This function is usually called every
2478 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
2479 * every tick. We fix it up based on jiffies.
2481 static void __update_cpu_load(struct rq
*this_rq
, unsigned long this_load
,
2482 unsigned long pending_updates
)
2486 this_rq
->nr_load_updates
++;
2488 /* Update our load: */
2489 this_rq
->cpu_load
[0] = this_load
; /* Fasttrack for idx 0 */
2490 for (i
= 1, scale
= 2; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2491 unsigned long old_load
, new_load
;
2493 /* scale is effectively 1 << i now, and >> i divides by scale */
2495 old_load
= this_rq
->cpu_load
[i
];
2496 old_load
= decay_load_missed(old_load
, pending_updates
- 1, i
);
2497 new_load
= this_load
;
2499 * Round up the averaging division if load is increasing. This
2500 * prevents us from getting stuck on 9 if the load is 10, for
2503 if (new_load
> old_load
)
2504 new_load
+= scale
- 1;
2506 this_rq
->cpu_load
[i
] = (old_load
* (scale
- 1) + new_load
) >> i
;
2509 sched_avg_update(this_rq
);
2514 * There is no sane way to deal with nohz on smp when using jiffies because the
2515 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
2516 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
2518 * Therefore we cannot use the delta approach from the regular tick since that
2519 * would seriously skew the load calculation. However we'll make do for those
2520 * updates happening while idle (nohz_idle_balance) or coming out of idle
2521 * (tick_nohz_idle_exit).
2523 * This means we might still be one tick off for nohz periods.
2527 * Called from nohz_idle_balance() to update the load ratings before doing the
2530 void update_idle_cpu_load(struct rq
*this_rq
)
2532 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2533 unsigned long load
= this_rq
->load
.weight
;
2534 unsigned long pending_updates
;
2537 * bail if there's load or we're actually up-to-date.
2539 if (load
|| curr_jiffies
== this_rq
->last_load_update_tick
)
2542 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2543 this_rq
->last_load_update_tick
= curr_jiffies
;
2545 __update_cpu_load(this_rq
, load
, pending_updates
);
2549 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
2551 void update_cpu_load_nohz(void)
2553 struct rq
*this_rq
= this_rq();
2554 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2555 unsigned long pending_updates
;
2557 if (curr_jiffies
== this_rq
->last_load_update_tick
)
2560 raw_spin_lock(&this_rq
->lock
);
2561 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2562 if (pending_updates
) {
2563 this_rq
->last_load_update_tick
= curr_jiffies
;
2565 * We were idle, this means load 0, the current load might be
2566 * !0 due to remote wakeups and the sort.
2568 __update_cpu_load(this_rq
, 0, pending_updates
);
2570 raw_spin_unlock(&this_rq
->lock
);
2572 #endif /* CONFIG_NO_HZ */
2575 * Called from scheduler_tick()
2577 static void update_cpu_load_active(struct rq
*this_rq
)
2580 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
2582 this_rq
->last_load_update_tick
= jiffies
;
2583 __update_cpu_load(this_rq
, this_rq
->load
.weight
, 1);
2585 calc_load_account_active(this_rq
);
2591 * sched_exec - execve() is a valuable balancing opportunity, because at
2592 * this point the task has the smallest effective memory and cache footprint.
2594 void sched_exec(void)
2596 struct task_struct
*p
= current
;
2597 unsigned long flags
;
2600 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2601 dest_cpu
= p
->sched_class
->select_task_rq(p
, SD_BALANCE_EXEC
, 0);
2602 if (dest_cpu
== smp_processor_id())
2605 if (likely(cpu_active(dest_cpu
))) {
2606 struct migration_arg arg
= { p
, dest_cpu
};
2608 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2609 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2613 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2618 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2619 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2621 EXPORT_PER_CPU_SYMBOL(kstat
);
2622 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2625 * Return any ns on the sched_clock that have not yet been accounted in
2626 * @p in case that task is currently running.
2628 * Called with task_rq_lock() held on @rq.
2630 static u64
do_task_delta_exec(struct task_struct
*p
, struct rq
*rq
)
2634 if (task_current(rq
, p
)) {
2635 update_rq_clock(rq
);
2636 ns
= rq
->clock_task
- p
->se
.exec_start
;
2644 unsigned long long task_delta_exec(struct task_struct
*p
)
2646 unsigned long flags
;
2650 rq
= task_rq_lock(p
, &flags
);
2651 ns
= do_task_delta_exec(p
, rq
);
2652 task_rq_unlock(rq
, p
, &flags
);
2658 * Return accounted runtime for the task.
2659 * In case the task is currently running, return the runtime plus current's
2660 * pending runtime that have not been accounted yet.
2662 unsigned long long task_sched_runtime(struct task_struct
*p
)
2664 unsigned long flags
;
2668 rq
= task_rq_lock(p
, &flags
);
2669 ns
= p
->se
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
2670 task_rq_unlock(rq
, p
, &flags
);
2676 * This function gets called by the timer code, with HZ frequency.
2677 * We call it with interrupts disabled.
2679 void scheduler_tick(void)
2681 int cpu
= smp_processor_id();
2682 struct rq
*rq
= cpu_rq(cpu
);
2683 struct task_struct
*curr
= rq
->curr
;
2687 raw_spin_lock(&rq
->lock
);
2688 update_rq_clock(rq
);
2689 update_cpu_load_active(rq
);
2690 curr
->sched_class
->task_tick(rq
, curr
, 0);
2691 raw_spin_unlock(&rq
->lock
);
2693 perf_event_task_tick();
2696 rq
->idle_balance
= idle_cpu(cpu
);
2697 trigger_load_balance(rq
, cpu
);
2701 notrace
unsigned long get_parent_ip(unsigned long addr
)
2703 if (in_lock_functions(addr
)) {
2704 addr
= CALLER_ADDR2
;
2705 if (in_lock_functions(addr
))
2706 addr
= CALLER_ADDR3
;
2711 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2712 defined(CONFIG_PREEMPT_TRACER))
2714 void __kprobes
add_preempt_count(int val
)
2716 #ifdef CONFIG_DEBUG_PREEMPT
2720 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2723 preempt_count() += val
;
2724 #ifdef CONFIG_DEBUG_PREEMPT
2726 * Spinlock count overflowing soon?
2728 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
2731 if (preempt_count() == val
)
2732 trace_preempt_off(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2734 EXPORT_SYMBOL(add_preempt_count
);
2736 void __kprobes
sub_preempt_count(int val
)
2738 #ifdef CONFIG_DEBUG_PREEMPT
2742 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
2745 * Is the spinlock portion underflowing?
2747 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
2748 !(preempt_count() & PREEMPT_MASK
)))
2752 if (preempt_count() == val
)
2753 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2754 preempt_count() -= val
;
2756 EXPORT_SYMBOL(sub_preempt_count
);
2761 * Print scheduling while atomic bug:
2763 static noinline
void __schedule_bug(struct task_struct
*prev
)
2765 if (oops_in_progress
)
2768 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
2769 prev
->comm
, prev
->pid
, preempt_count());
2771 debug_show_held_locks(prev
);
2773 if (irqs_disabled())
2774 print_irqtrace_events(prev
);
2776 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
2780 * Various schedule()-time debugging checks and statistics:
2782 static inline void schedule_debug(struct task_struct
*prev
)
2785 * Test if we are atomic. Since do_exit() needs to call into
2786 * schedule() atomically, we ignore that path for now.
2787 * Otherwise, whine if we are scheduling when we should not be.
2789 if (unlikely(in_atomic_preempt_off() && !prev
->exit_state
))
2790 __schedule_bug(prev
);
2793 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2795 schedstat_inc(this_rq(), sched_count
);
2798 static void put_prev_task(struct rq
*rq
, struct task_struct
*prev
)
2800 if (prev
->on_rq
|| rq
->skip_clock_update
< 0)
2801 update_rq_clock(rq
);
2802 prev
->sched_class
->put_prev_task(rq
, prev
);
2806 * Pick up the highest-prio task:
2808 static inline struct task_struct
*
2809 pick_next_task(struct rq
*rq
)
2811 const struct sched_class
*class;
2812 struct task_struct
*p
;
2815 * Optimization: we know that if all tasks are in
2816 * the fair class we can call that function directly:
2818 if (likely(rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
2819 p
= fair_sched_class
.pick_next_task(rq
);
2824 for_each_class(class) {
2825 p
= class->pick_next_task(rq
);
2830 BUG(); /* the idle class will always have a runnable task */
2834 * __schedule() is the main scheduler function.
2836 * The main means of driving the scheduler and thus entering this function are:
2838 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2840 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2841 * paths. For example, see arch/x86/entry_64.S.
2843 * To drive preemption between tasks, the scheduler sets the flag in timer
2844 * interrupt handler scheduler_tick().
2846 * 3. Wakeups don't really cause entry into schedule(). They add a
2847 * task to the run-queue and that's it.
2849 * Now, if the new task added to the run-queue preempts the current
2850 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2851 * called on the nearest possible occasion:
2853 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2855 * - in syscall or exception context, at the next outmost
2856 * preempt_enable(). (this might be as soon as the wake_up()'s
2859 * - in IRQ context, return from interrupt-handler to
2860 * preemptible context
2862 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2865 * - cond_resched() call
2866 * - explicit schedule() call
2867 * - return from syscall or exception to user-space
2868 * - return from interrupt-handler to user-space
2870 static void __sched
__schedule(void)
2872 struct task_struct
*prev
, *next
;
2873 unsigned long *switch_count
;
2879 cpu
= smp_processor_id();
2881 rcu_note_context_switch(cpu
);
2884 schedule_debug(prev
);
2886 if (sched_feat(HRTICK
))
2889 raw_spin_lock_irq(&rq
->lock
);
2891 switch_count
= &prev
->nivcsw
;
2892 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2893 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
2894 prev
->state
= TASK_RUNNING
;
2896 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
2900 * If a worker went to sleep, notify and ask workqueue
2901 * whether it wants to wake up a task to maintain
2904 if (prev
->flags
& PF_WQ_WORKER
) {
2905 struct task_struct
*to_wakeup
;
2907 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
2909 try_to_wake_up_local(to_wakeup
);
2912 switch_count
= &prev
->nvcsw
;
2915 pre_schedule(rq
, prev
);
2917 if (unlikely(!rq
->nr_running
))
2918 idle_balance(cpu
, rq
);
2920 put_prev_task(rq
, prev
);
2921 next
= pick_next_task(rq
);
2922 clear_tsk_need_resched(prev
);
2923 rq
->skip_clock_update
= 0;
2925 if (likely(prev
!= next
)) {
2930 context_switch(rq
, prev
, next
); /* unlocks the rq */
2932 * The context switch have flipped the stack from under us
2933 * and restored the local variables which were saved when
2934 * this task called schedule() in the past. prev == current
2935 * is still correct, but it can be moved to another cpu/rq.
2937 cpu
= smp_processor_id();
2940 raw_spin_unlock_irq(&rq
->lock
);
2944 sched_preempt_enable_no_resched();
2949 static inline void sched_submit_work(struct task_struct
*tsk
)
2951 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
2954 * If we are going to sleep and we have plugged IO queued,
2955 * make sure to submit it to avoid deadlocks.
2957 if (blk_needs_flush_plug(tsk
))
2958 blk_schedule_flush_plug(tsk
);
2961 asmlinkage
void __sched
schedule(void)
2963 struct task_struct
*tsk
= current
;
2965 sched_submit_work(tsk
);
2968 EXPORT_SYMBOL(schedule
);
2970 #ifdef CONFIG_CONTEXT_TRACKING
2971 asmlinkage
void __sched
schedule_user(void)
2974 * If we come here after a random call to set_need_resched(),
2975 * or we have been woken up remotely but the IPI has not yet arrived,
2976 * we haven't yet exited the RCU idle mode. Do it here manually until
2977 * we find a better solution.
2986 * schedule_preempt_disabled - called with preemption disabled
2988 * Returns with preemption disabled. Note: preempt_count must be 1
2990 void __sched
schedule_preempt_disabled(void)
2992 sched_preempt_enable_no_resched();
2997 #ifdef CONFIG_PREEMPT
2999 * this is the entry point to schedule() from in-kernel preemption
3000 * off of preempt_enable. Kernel preemptions off return from interrupt
3001 * occur there and call schedule directly.
3003 asmlinkage
void __sched notrace
preempt_schedule(void)
3005 struct thread_info
*ti
= current_thread_info();
3008 * If there is a non-zero preempt_count or interrupts are disabled,
3009 * we do not want to preempt the current task. Just return..
3011 if (likely(ti
->preempt_count
|| irqs_disabled()))
3015 add_preempt_count_notrace(PREEMPT_ACTIVE
);
3017 sub_preempt_count_notrace(PREEMPT_ACTIVE
);
3020 * Check again in case we missed a preemption opportunity
3021 * between schedule and now.
3024 } while (need_resched());
3026 EXPORT_SYMBOL(preempt_schedule
);
3029 * this is the entry point to schedule() from kernel preemption
3030 * off of irq context.
3031 * Note, that this is called and return with irqs disabled. This will
3032 * protect us against recursive calling from irq.
3034 asmlinkage
void __sched
preempt_schedule_irq(void)
3036 struct thread_info
*ti
= current_thread_info();
3037 enum ctx_state prev_state
;
3039 /* Catch callers which need to be fixed */
3040 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3042 prev_state
= exception_enter();
3045 add_preempt_count(PREEMPT_ACTIVE
);
3048 local_irq_disable();
3049 sub_preempt_count(PREEMPT_ACTIVE
);
3052 * Check again in case we missed a preemption opportunity
3053 * between schedule and now.
3056 } while (need_resched());
3058 exception_exit(prev_state
);
3061 #endif /* CONFIG_PREEMPT */
3063 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
3066 return try_to_wake_up(curr
->private, mode
, wake_flags
);
3068 EXPORT_SYMBOL(default_wake_function
);
3071 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3072 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3073 * number) then we wake all the non-exclusive tasks and one exclusive task.
3075 * There are circumstances in which we can try to wake a task which has already
3076 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3077 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3079 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3080 int nr_exclusive
, int wake_flags
, void *key
)
3082 wait_queue_t
*curr
, *next
;
3084 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3085 unsigned flags
= curr
->flags
;
3087 if (curr
->func(curr
, mode
, wake_flags
, key
) &&
3088 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3094 * __wake_up - wake up threads blocked on a waitqueue.
3096 * @mode: which threads
3097 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3098 * @key: is directly passed to the wakeup function
3100 * It may be assumed that this function implies a write memory barrier before
3101 * changing the task state if and only if any tasks are woken up.
3103 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3104 int nr_exclusive
, void *key
)
3106 unsigned long flags
;
3108 spin_lock_irqsave(&q
->lock
, flags
);
3109 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3110 spin_unlock_irqrestore(&q
->lock
, flags
);
3112 EXPORT_SYMBOL(__wake_up
);
3115 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3117 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
, int nr
)
3119 __wake_up_common(q
, mode
, nr
, 0, NULL
);
3121 EXPORT_SYMBOL_GPL(__wake_up_locked
);
3123 void __wake_up_locked_key(wait_queue_head_t
*q
, unsigned int mode
, void *key
)
3125 __wake_up_common(q
, mode
, 1, 0, key
);
3127 EXPORT_SYMBOL_GPL(__wake_up_locked_key
);
3130 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
3132 * @mode: which threads
3133 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3134 * @key: opaque value to be passed to wakeup targets
3136 * The sync wakeup differs that the waker knows that it will schedule
3137 * away soon, so while the target thread will be woken up, it will not
3138 * be migrated to another CPU - ie. the two threads are 'synchronized'
3139 * with each other. This can prevent needless bouncing between CPUs.
3141 * On UP it can prevent extra preemption.
3143 * It may be assumed that this function implies a write memory barrier before
3144 * changing the task state if and only if any tasks are woken up.
3146 void __wake_up_sync_key(wait_queue_head_t
*q
, unsigned int mode
,
3147 int nr_exclusive
, void *key
)
3149 unsigned long flags
;
3150 int wake_flags
= WF_SYNC
;
3155 if (unlikely(!nr_exclusive
))
3158 spin_lock_irqsave(&q
->lock
, flags
);
3159 __wake_up_common(q
, mode
, nr_exclusive
, wake_flags
, key
);
3160 spin_unlock_irqrestore(&q
->lock
, flags
);
3162 EXPORT_SYMBOL_GPL(__wake_up_sync_key
);
3165 * __wake_up_sync - see __wake_up_sync_key()
3167 void __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3169 __wake_up_sync_key(q
, mode
, nr_exclusive
, NULL
);
3171 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3174 * complete: - signals a single thread waiting on this completion
3175 * @x: holds the state of this particular completion
3177 * This will wake up a single thread waiting on this completion. Threads will be
3178 * awakened in the same order in which they were queued.
3180 * See also complete_all(), wait_for_completion() and related routines.
3182 * It may be assumed that this function implies a write memory barrier before
3183 * changing the task state if and only if any tasks are woken up.
3185 void complete(struct completion
*x
)
3187 unsigned long flags
;
3189 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3191 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
3192 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3194 EXPORT_SYMBOL(complete
);
3197 * complete_all: - signals all threads waiting on this completion
3198 * @x: holds the state of this particular completion
3200 * This will wake up all threads waiting on this particular completion event.
3202 * It may be assumed that this function implies a write memory barrier before
3203 * changing the task state if and only if any tasks are woken up.
3205 void complete_all(struct completion
*x
)
3207 unsigned long flags
;
3209 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3210 x
->done
+= UINT_MAX
/2;
3211 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
3212 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3214 EXPORT_SYMBOL(complete_all
);
3216 static inline long __sched
3217 do_wait_for_common(struct completion
*x
,
3218 long (*action
)(long), long timeout
, int state
)
3221 DECLARE_WAITQUEUE(wait
, current
);
3223 __add_wait_queue_tail_exclusive(&x
->wait
, &wait
);
3225 if (signal_pending_state(state
, current
)) {
3226 timeout
= -ERESTARTSYS
;
3229 __set_current_state(state
);
3230 spin_unlock_irq(&x
->wait
.lock
);
3231 timeout
= action(timeout
);
3232 spin_lock_irq(&x
->wait
.lock
);
3233 } while (!x
->done
&& timeout
);
3234 __remove_wait_queue(&x
->wait
, &wait
);
3239 return timeout
?: 1;
3242 static inline long __sched
3243 __wait_for_common(struct completion
*x
,
3244 long (*action
)(long), long timeout
, int state
)
3248 spin_lock_irq(&x
->wait
.lock
);
3249 timeout
= do_wait_for_common(x
, action
, timeout
, state
);
3250 spin_unlock_irq(&x
->wait
.lock
);
3255 wait_for_common(struct completion
*x
, long timeout
, int state
)
3257 return __wait_for_common(x
, schedule_timeout
, timeout
, state
);
3261 wait_for_common_io(struct completion
*x
, long timeout
, int state
)
3263 return __wait_for_common(x
, io_schedule_timeout
, timeout
, state
);
3267 * wait_for_completion: - waits for completion of a task
3268 * @x: holds the state of this particular completion
3270 * This waits to be signaled for completion of a specific task. It is NOT
3271 * interruptible and there is no timeout.
3273 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
3274 * and interrupt capability. Also see complete().
3276 void __sched
wait_for_completion(struct completion
*x
)
3278 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3280 EXPORT_SYMBOL(wait_for_completion
);
3283 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
3284 * @x: holds the state of this particular completion
3285 * @timeout: timeout value in jiffies
3287 * This waits for either a completion of a specific task to be signaled or for a
3288 * specified timeout to expire. The timeout is in jiffies. It is not
3291 * The return value is 0 if timed out, and positive (at least 1, or number of
3292 * jiffies left till timeout) if completed.
3294 unsigned long __sched
3295 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3297 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3299 EXPORT_SYMBOL(wait_for_completion_timeout
);
3302 * wait_for_completion_io: - waits for completion of a task
3303 * @x: holds the state of this particular completion
3305 * This waits to be signaled for completion of a specific task. It is NOT
3306 * interruptible and there is no timeout. The caller is accounted as waiting
3309 void __sched
wait_for_completion_io(struct completion
*x
)
3311 wait_for_common_io(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3313 EXPORT_SYMBOL(wait_for_completion_io
);
3316 * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout)
3317 * @x: holds the state of this particular completion
3318 * @timeout: timeout value in jiffies
3320 * This waits for either a completion of a specific task to be signaled or for a
3321 * specified timeout to expire. The timeout is in jiffies. It is not
3322 * interruptible. The caller is accounted as waiting for IO.
3324 * The return value is 0 if timed out, and positive (at least 1, or number of
3325 * jiffies left till timeout) if completed.
3327 unsigned long __sched
3328 wait_for_completion_io_timeout(struct completion
*x
, unsigned long timeout
)
3330 return wait_for_common_io(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3332 EXPORT_SYMBOL(wait_for_completion_io_timeout
);
3335 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
3336 * @x: holds the state of this particular completion
3338 * This waits for completion of a specific task to be signaled. It is
3341 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3343 int __sched
wait_for_completion_interruptible(struct completion
*x
)
3345 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
3346 if (t
== -ERESTARTSYS
)
3350 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3353 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
3354 * @x: holds the state of this particular completion
3355 * @timeout: timeout value in jiffies
3357 * This waits for either a completion of a specific task to be signaled or for a
3358 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
3360 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3361 * positive (at least 1, or number of jiffies left till timeout) if completed.
3364 wait_for_completion_interruptible_timeout(struct completion
*x
,
3365 unsigned long timeout
)
3367 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
3369 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3372 * wait_for_completion_killable: - waits for completion of a task (killable)
3373 * @x: holds the state of this particular completion
3375 * This waits to be signaled for completion of a specific task. It can be
3376 * interrupted by a kill signal.
3378 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3380 int __sched
wait_for_completion_killable(struct completion
*x
)
3382 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
3383 if (t
== -ERESTARTSYS
)
3387 EXPORT_SYMBOL(wait_for_completion_killable
);
3390 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
3391 * @x: holds the state of this particular completion
3392 * @timeout: timeout value in jiffies
3394 * This waits for either a completion of a specific task to be
3395 * signaled or for a specified timeout to expire. It can be
3396 * interrupted by a kill signal. The timeout is in jiffies.
3398 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3399 * positive (at least 1, or number of jiffies left till timeout) if completed.
3402 wait_for_completion_killable_timeout(struct completion
*x
,
3403 unsigned long timeout
)
3405 return wait_for_common(x
, timeout
, TASK_KILLABLE
);
3407 EXPORT_SYMBOL(wait_for_completion_killable_timeout
);
3410 * try_wait_for_completion - try to decrement a completion without blocking
3411 * @x: completion structure
3413 * Returns: 0 if a decrement cannot be done without blocking
3414 * 1 if a decrement succeeded.
3416 * If a completion is being used as a counting completion,
3417 * attempt to decrement the counter without blocking. This
3418 * enables us to avoid waiting if the resource the completion
3419 * is protecting is not available.
3421 bool try_wait_for_completion(struct completion
*x
)
3423 unsigned long flags
;
3426 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3431 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3434 EXPORT_SYMBOL(try_wait_for_completion
);
3437 * completion_done - Test to see if a completion has any waiters
3438 * @x: completion structure
3440 * Returns: 0 if there are waiters (wait_for_completion() in progress)
3441 * 1 if there are no waiters.
3444 bool completion_done(struct completion
*x
)
3446 unsigned long flags
;
3449 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3452 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3455 EXPORT_SYMBOL(completion_done
);
3458 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
3460 unsigned long flags
;
3463 init_waitqueue_entry(&wait
, current
);
3465 __set_current_state(state
);
3467 spin_lock_irqsave(&q
->lock
, flags
);
3468 __add_wait_queue(q
, &wait
);
3469 spin_unlock(&q
->lock
);
3470 timeout
= schedule_timeout(timeout
);
3471 spin_lock_irq(&q
->lock
);
3472 __remove_wait_queue(q
, &wait
);
3473 spin_unlock_irqrestore(&q
->lock
, flags
);
3478 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3480 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3482 EXPORT_SYMBOL(interruptible_sleep_on
);
3485 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3487 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
3489 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3491 void __sched
sleep_on(wait_queue_head_t
*q
)
3493 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3495 EXPORT_SYMBOL(sleep_on
);
3497 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3499 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
3501 EXPORT_SYMBOL(sleep_on_timeout
);
3503 #ifdef CONFIG_RT_MUTEXES
3506 * rt_mutex_setprio - set the current priority of a task
3508 * @prio: prio value (kernel-internal form)
3510 * This function changes the 'effective' priority of a task. It does
3511 * not touch ->normal_prio like __setscheduler().
3513 * Used by the rt_mutex code to implement priority inheritance logic.
3515 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3517 int oldprio
, on_rq
, running
;
3519 const struct sched_class
*prev_class
;
3521 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3523 rq
= __task_rq_lock(p
);
3526 * Idle task boosting is a nono in general. There is one
3527 * exception, when PREEMPT_RT and NOHZ is active:
3529 * The idle task calls get_next_timer_interrupt() and holds
3530 * the timer wheel base->lock on the CPU and another CPU wants
3531 * to access the timer (probably to cancel it). We can safely
3532 * ignore the boosting request, as the idle CPU runs this code
3533 * with interrupts disabled and will complete the lock
3534 * protected section without being interrupted. So there is no
3535 * real need to boost.
3537 if (unlikely(p
== rq
->idle
)) {
3538 WARN_ON(p
!= rq
->curr
);
3539 WARN_ON(p
->pi_blocked_on
);
3543 trace_sched_pi_setprio(p
, prio
);
3545 prev_class
= p
->sched_class
;
3547 running
= task_current(rq
, p
);
3549 dequeue_task(rq
, p
, 0);
3551 p
->sched_class
->put_prev_task(rq
, p
);
3554 p
->sched_class
= &rt_sched_class
;
3556 p
->sched_class
= &fair_sched_class
;
3561 p
->sched_class
->set_curr_task(rq
);
3563 enqueue_task(rq
, p
, oldprio
< prio
? ENQUEUE_HEAD
: 0);
3565 check_class_changed(rq
, p
, prev_class
, oldprio
);
3567 __task_rq_unlock(rq
);
3570 void set_user_nice(struct task_struct
*p
, long nice
)
3572 int old_prio
, delta
, on_rq
;
3573 unsigned long flags
;
3576 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3579 * We have to be careful, if called from sys_setpriority(),
3580 * the task might be in the middle of scheduling on another CPU.
3582 rq
= task_rq_lock(p
, &flags
);
3584 * The RT priorities are set via sched_setscheduler(), but we still
3585 * allow the 'normal' nice value to be set - but as expected
3586 * it wont have any effect on scheduling until the task is
3587 * SCHED_FIFO/SCHED_RR:
3589 if (task_has_rt_policy(p
)) {
3590 p
->static_prio
= NICE_TO_PRIO(nice
);
3595 dequeue_task(rq
, p
, 0);
3597 p
->static_prio
= NICE_TO_PRIO(nice
);
3600 p
->prio
= effective_prio(p
);
3601 delta
= p
->prio
- old_prio
;
3604 enqueue_task(rq
, p
, 0);
3606 * If the task increased its priority or is running and
3607 * lowered its priority, then reschedule its CPU:
3609 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3610 resched_task(rq
->curr
);
3613 task_rq_unlock(rq
, p
, &flags
);
3615 EXPORT_SYMBOL(set_user_nice
);
3618 * can_nice - check if a task can reduce its nice value
3622 int can_nice(const struct task_struct
*p
, const int nice
)
3624 /* convert nice value [19,-20] to rlimit style value [1,40] */
3625 int nice_rlim
= 20 - nice
;
3627 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3628 capable(CAP_SYS_NICE
));
3631 #ifdef __ARCH_WANT_SYS_NICE
3634 * sys_nice - change the priority of the current process.
3635 * @increment: priority increment
3637 * sys_setpriority is a more generic, but much slower function that
3638 * does similar things.
3640 SYSCALL_DEFINE1(nice
, int, increment
)
3645 * Setpriority might change our priority at the same moment.
3646 * We don't have to worry. Conceptually one call occurs first
3647 * and we have a single winner.
3649 if (increment
< -40)
3654 nice
= TASK_NICE(current
) + increment
;
3660 if (increment
< 0 && !can_nice(current
, nice
))
3663 retval
= security_task_setnice(current
, nice
);
3667 set_user_nice(current
, nice
);
3674 * task_prio - return the priority value of a given task.
3675 * @p: the task in question.
3677 * This is the priority value as seen by users in /proc.
3678 * RT tasks are offset by -200. Normal tasks are centered
3679 * around 0, value goes from -16 to +15.
3681 int task_prio(const struct task_struct
*p
)
3683 return p
->prio
- MAX_RT_PRIO
;
3687 * task_nice - return the nice value of a given task.
3688 * @p: the task in question.
3690 int task_nice(const struct task_struct
*p
)
3692 return TASK_NICE(p
);
3694 EXPORT_SYMBOL(task_nice
);
3697 * idle_cpu - is a given cpu idle currently?
3698 * @cpu: the processor in question.
3700 int idle_cpu(int cpu
)
3702 struct rq
*rq
= cpu_rq(cpu
);
3704 if (rq
->curr
!= rq
->idle
)
3711 if (!llist_empty(&rq
->wake_list
))
3719 * idle_task - return the idle task for a given cpu.
3720 * @cpu: the processor in question.
3722 struct task_struct
*idle_task(int cpu
)
3724 return cpu_rq(cpu
)->idle
;
3728 * find_process_by_pid - find a process with a matching PID value.
3729 * @pid: the pid in question.
3731 static struct task_struct
*find_process_by_pid(pid_t pid
)
3733 return pid
? find_task_by_vpid(pid
) : current
;
3736 /* Actually do priority change: must hold rq lock. */
3738 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
3741 p
->rt_priority
= prio
;
3742 p
->normal_prio
= normal_prio(p
);
3743 /* we are holding p->pi_lock already */
3744 p
->prio
= rt_mutex_getprio(p
);
3745 if (rt_prio(p
->prio
))
3746 p
->sched_class
= &rt_sched_class
;
3748 p
->sched_class
= &fair_sched_class
;
3753 * check the target process has a UID that matches the current process's
3755 static bool check_same_owner(struct task_struct
*p
)
3757 const struct cred
*cred
= current_cred(), *pcred
;
3761 pcred
= __task_cred(p
);
3762 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3763 uid_eq(cred
->euid
, pcred
->uid
));
3768 static int __sched_setscheduler(struct task_struct
*p
, int policy
,
3769 const struct sched_param
*param
, bool user
)
3771 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
3772 unsigned long flags
;
3773 const struct sched_class
*prev_class
;
3777 /* may grab non-irq protected spin_locks */
3778 BUG_ON(in_interrupt());
3780 /* double check policy once rq lock held */
3782 reset_on_fork
= p
->sched_reset_on_fork
;
3783 policy
= oldpolicy
= p
->policy
;
3785 reset_on_fork
= !!(policy
& SCHED_RESET_ON_FORK
);
3786 policy
&= ~SCHED_RESET_ON_FORK
;
3788 if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3789 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
3790 policy
!= SCHED_IDLE
)
3795 * Valid priorities for SCHED_FIFO and SCHED_RR are
3796 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3797 * SCHED_BATCH and SCHED_IDLE is 0.
3799 if (param
->sched_priority
< 0 ||
3800 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3801 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3803 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
3807 * Allow unprivileged RT tasks to decrease priority:
3809 if (user
&& !capable(CAP_SYS_NICE
)) {
3810 if (rt_policy(policy
)) {
3811 unsigned long rlim_rtprio
=
3812 task_rlimit(p
, RLIMIT_RTPRIO
);
3814 /* can't set/change the rt policy */
3815 if (policy
!= p
->policy
&& !rlim_rtprio
)
3818 /* can't increase priority */
3819 if (param
->sched_priority
> p
->rt_priority
&&
3820 param
->sched_priority
> rlim_rtprio
)
3825 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3826 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3828 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
3829 if (!can_nice(p
, TASK_NICE(p
)))
3833 /* can't change other user's priorities */
3834 if (!check_same_owner(p
))
3837 /* Normal users shall not reset the sched_reset_on_fork flag */
3838 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3843 retval
= security_task_setscheduler(p
);
3849 * make sure no PI-waiters arrive (or leave) while we are
3850 * changing the priority of the task:
3852 * To be able to change p->policy safely, the appropriate
3853 * runqueue lock must be held.
3855 rq
= task_rq_lock(p
, &flags
);
3858 * Changing the policy of the stop threads its a very bad idea
3860 if (p
== rq
->stop
) {
3861 task_rq_unlock(rq
, p
, &flags
);
3866 * If not changing anything there's no need to proceed further:
3868 if (unlikely(policy
== p
->policy
&& (!rt_policy(policy
) ||
3869 param
->sched_priority
== p
->rt_priority
))) {
3870 task_rq_unlock(rq
, p
, &flags
);
3874 #ifdef CONFIG_RT_GROUP_SCHED
3877 * Do not allow realtime tasks into groups that have no runtime
3880 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
3881 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
3882 !task_group_is_autogroup(task_group(p
))) {
3883 task_rq_unlock(rq
, p
, &flags
);
3889 /* recheck policy now with rq lock held */
3890 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3891 policy
= oldpolicy
= -1;
3892 task_rq_unlock(rq
, p
, &flags
);
3896 running
= task_current(rq
, p
);
3898 dequeue_task(rq
, p
, 0);
3900 p
->sched_class
->put_prev_task(rq
, p
);
3902 p
->sched_reset_on_fork
= reset_on_fork
;
3905 prev_class
= p
->sched_class
;
3906 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
3909 p
->sched_class
->set_curr_task(rq
);
3911 enqueue_task(rq
, p
, 0);
3913 check_class_changed(rq
, p
, prev_class
, oldprio
);
3914 task_rq_unlock(rq
, p
, &flags
);
3916 rt_mutex_adjust_pi(p
);
3922 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3923 * @p: the task in question.
3924 * @policy: new policy.
3925 * @param: structure containing the new RT priority.
3927 * NOTE that the task may be already dead.
3929 int sched_setscheduler(struct task_struct
*p
, int policy
,
3930 const struct sched_param
*param
)
3932 return __sched_setscheduler(p
, policy
, param
, true);
3934 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3937 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3938 * @p: the task in question.
3939 * @policy: new policy.
3940 * @param: structure containing the new RT priority.
3942 * Just like sched_setscheduler, only don't bother checking if the
3943 * current context has permission. For example, this is needed in
3944 * stop_machine(): we create temporary high priority worker threads,
3945 * but our caller might not have that capability.
3947 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
3948 const struct sched_param
*param
)
3950 return __sched_setscheduler(p
, policy
, param
, false);
3954 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3956 struct sched_param lparam
;
3957 struct task_struct
*p
;
3960 if (!param
|| pid
< 0)
3962 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3967 p
= find_process_by_pid(pid
);
3969 retval
= sched_setscheduler(p
, policy
, &lparam
);
3976 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3977 * @pid: the pid in question.
3978 * @policy: new policy.
3979 * @param: structure containing the new RT priority.
3981 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
3982 struct sched_param __user
*, param
)
3984 /* negative values for policy are not valid */
3988 return do_sched_setscheduler(pid
, policy
, param
);
3992 * sys_sched_setparam - set/change the RT priority of a thread
3993 * @pid: the pid in question.
3994 * @param: structure containing the new RT priority.
3996 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
3998 return do_sched_setscheduler(pid
, -1, param
);
4002 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4003 * @pid: the pid in question.
4005 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
4007 struct task_struct
*p
;
4015 p
= find_process_by_pid(pid
);
4017 retval
= security_task_getscheduler(p
);
4020 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
4027 * sys_sched_getparam - get the RT priority of a thread
4028 * @pid: the pid in question.
4029 * @param: structure containing the RT priority.
4031 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4033 struct sched_param lp
;
4034 struct task_struct
*p
;
4037 if (!param
|| pid
< 0)
4041 p
= find_process_by_pid(pid
);
4046 retval
= security_task_getscheduler(p
);
4050 lp
.sched_priority
= p
->rt_priority
;
4054 * This one might sleep, we cannot do it with a spinlock held ...
4056 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4065 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
4067 cpumask_var_t cpus_allowed
, new_mask
;
4068 struct task_struct
*p
;
4074 p
= find_process_by_pid(pid
);
4081 /* Prevent p going away */
4085 if (p
->flags
& PF_NO_SETAFFINITY
) {
4089 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4093 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4095 goto out_free_cpus_allowed
;
4098 if (!check_same_owner(p
)) {
4100 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4107 retval
= security_task_setscheduler(p
);
4111 cpuset_cpus_allowed(p
, cpus_allowed
);
4112 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4114 retval
= set_cpus_allowed_ptr(p
, new_mask
);
4117 cpuset_cpus_allowed(p
, cpus_allowed
);
4118 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4120 * We must have raced with a concurrent cpuset
4121 * update. Just reset the cpus_allowed to the
4122 * cpuset's cpus_allowed
4124 cpumask_copy(new_mask
, cpus_allowed
);
4129 free_cpumask_var(new_mask
);
4130 out_free_cpus_allowed
:
4131 free_cpumask_var(cpus_allowed
);
4138 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4139 struct cpumask
*new_mask
)
4141 if (len
< cpumask_size())
4142 cpumask_clear(new_mask
);
4143 else if (len
> cpumask_size())
4144 len
= cpumask_size();
4146 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4150 * sys_sched_setaffinity - set the cpu affinity of a process
4151 * @pid: pid of the process
4152 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4153 * @user_mask_ptr: user-space pointer to the new cpu mask
4155 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4156 unsigned long __user
*, user_mask_ptr
)
4158 cpumask_var_t new_mask
;
4161 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4164 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4166 retval
= sched_setaffinity(pid
, new_mask
);
4167 free_cpumask_var(new_mask
);
4171 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4173 struct task_struct
*p
;
4174 unsigned long flags
;
4181 p
= find_process_by_pid(pid
);
4185 retval
= security_task_getscheduler(p
);
4189 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4190 cpumask_and(mask
, &p
->cpus_allowed
, cpu_online_mask
);
4191 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4201 * sys_sched_getaffinity - get the cpu affinity of a process
4202 * @pid: pid of the process
4203 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4204 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4206 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4207 unsigned long __user
*, user_mask_ptr
)
4212 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4214 if (len
& (sizeof(unsigned long)-1))
4217 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4220 ret
= sched_getaffinity(pid
, mask
);
4222 size_t retlen
= min_t(size_t, len
, cpumask_size());
4224 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4229 free_cpumask_var(mask
);
4235 * sys_sched_yield - yield the current processor to other threads.
4237 * This function yields the current CPU to other tasks. If there are no
4238 * other threads running on this CPU then this function will return.
4240 SYSCALL_DEFINE0(sched_yield
)
4242 struct rq
*rq
= this_rq_lock();
4244 schedstat_inc(rq
, yld_count
);
4245 current
->sched_class
->yield_task(rq
);
4248 * Since we are going to call schedule() anyway, there's
4249 * no need to preempt or enable interrupts:
4251 __release(rq
->lock
);
4252 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4253 do_raw_spin_unlock(&rq
->lock
);
4254 sched_preempt_enable_no_resched();
4261 static inline int should_resched(void)
4263 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE
);
4266 static void __cond_resched(void)
4268 add_preempt_count(PREEMPT_ACTIVE
);
4270 sub_preempt_count(PREEMPT_ACTIVE
);
4273 int __sched
_cond_resched(void)
4275 if (should_resched()) {
4281 EXPORT_SYMBOL(_cond_resched
);
4284 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4285 * call schedule, and on return reacquire the lock.
4287 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4288 * operations here to prevent schedule() from being called twice (once via
4289 * spin_unlock(), once by hand).
4291 int __cond_resched_lock(spinlock_t
*lock
)
4293 int resched
= should_resched();
4296 lockdep_assert_held(lock
);
4298 if (spin_needbreak(lock
) || resched
) {
4309 EXPORT_SYMBOL(__cond_resched_lock
);
4311 int __sched
__cond_resched_softirq(void)
4313 BUG_ON(!in_softirq());
4315 if (should_resched()) {
4323 EXPORT_SYMBOL(__cond_resched_softirq
);
4326 * yield - yield the current processor to other threads.
4328 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4330 * The scheduler is at all times free to pick the calling task as the most
4331 * eligible task to run, if removing the yield() call from your code breaks
4332 * it, its already broken.
4334 * Typical broken usage is:
4339 * where one assumes that yield() will let 'the other' process run that will
4340 * make event true. If the current task is a SCHED_FIFO task that will never
4341 * happen. Never use yield() as a progress guarantee!!
4343 * If you want to use yield() to wait for something, use wait_event().
4344 * If you want to use yield() to be 'nice' for others, use cond_resched().
4345 * If you still want to use yield(), do not!
4347 void __sched
yield(void)
4349 set_current_state(TASK_RUNNING
);
4352 EXPORT_SYMBOL(yield
);
4355 * yield_to - yield the current processor to another thread in
4356 * your thread group, or accelerate that thread toward the
4357 * processor it's on.
4359 * @preempt: whether task preemption is allowed or not
4361 * It's the caller's job to ensure that the target task struct
4362 * can't go away on us before we can do any checks.
4365 * true (>0) if we indeed boosted the target task.
4366 * false (0) if we failed to boost the target.
4367 * -ESRCH if there's no task to yield to.
4369 bool __sched
yield_to(struct task_struct
*p
, bool preempt
)
4371 struct task_struct
*curr
= current
;
4372 struct rq
*rq
, *p_rq
;
4373 unsigned long flags
;
4376 local_irq_save(flags
);
4382 * If we're the only runnable task on the rq and target rq also
4383 * has only one task, there's absolutely no point in yielding.
4385 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4390 double_rq_lock(rq
, p_rq
);
4391 while (task_rq(p
) != p_rq
) {
4392 double_rq_unlock(rq
, p_rq
);
4396 if (!curr
->sched_class
->yield_to_task
)
4399 if (curr
->sched_class
!= p
->sched_class
)
4402 if (task_running(p_rq
, p
) || p
->state
)
4405 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4407 schedstat_inc(rq
, yld_count
);
4409 * Make p's CPU reschedule; pick_next_entity takes care of
4412 if (preempt
&& rq
!= p_rq
)
4413 resched_task(p_rq
->curr
);
4417 double_rq_unlock(rq
, p_rq
);
4419 local_irq_restore(flags
);
4426 EXPORT_SYMBOL_GPL(yield_to
);
4429 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4430 * that process accounting knows that this is a task in IO wait state.
4432 void __sched
io_schedule(void)
4434 struct rq
*rq
= raw_rq();
4436 delayacct_blkio_start();
4437 atomic_inc(&rq
->nr_iowait
);
4438 blk_flush_plug(current
);
4439 current
->in_iowait
= 1;
4441 current
->in_iowait
= 0;
4442 atomic_dec(&rq
->nr_iowait
);
4443 delayacct_blkio_end();
4445 EXPORT_SYMBOL(io_schedule
);
4447 long __sched
io_schedule_timeout(long timeout
)
4449 struct rq
*rq
= raw_rq();
4452 delayacct_blkio_start();
4453 atomic_inc(&rq
->nr_iowait
);
4454 blk_flush_plug(current
);
4455 current
->in_iowait
= 1;
4456 ret
= schedule_timeout(timeout
);
4457 current
->in_iowait
= 0;
4458 atomic_dec(&rq
->nr_iowait
);
4459 delayacct_blkio_end();
4464 * sys_sched_get_priority_max - return maximum RT priority.
4465 * @policy: scheduling class.
4467 * this syscall returns the maximum rt_priority that can be used
4468 * by a given scheduling class.
4470 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
4477 ret
= MAX_USER_RT_PRIO
-1;
4489 * sys_sched_get_priority_min - return minimum RT priority.
4490 * @policy: scheduling class.
4492 * this syscall returns the minimum rt_priority that can be used
4493 * by a given scheduling class.
4495 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
4513 * sys_sched_rr_get_interval - return the default timeslice of a process.
4514 * @pid: pid of the process.
4515 * @interval: userspace pointer to the timeslice value.
4517 * this syscall writes the default timeslice value of a given process
4518 * into the user-space timespec buffer. A value of '0' means infinity.
4520 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
4521 struct timespec __user
*, interval
)
4523 struct task_struct
*p
;
4524 unsigned int time_slice
;
4525 unsigned long flags
;
4535 p
= find_process_by_pid(pid
);
4539 retval
= security_task_getscheduler(p
);
4543 rq
= task_rq_lock(p
, &flags
);
4544 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
4545 task_rq_unlock(rq
, p
, &flags
);
4548 jiffies_to_timespec(time_slice
, &t
);
4549 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4557 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
4559 void sched_show_task(struct task_struct
*p
)
4561 unsigned long free
= 0;
4565 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4566 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
4567 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4568 #if BITS_PER_LONG == 32
4569 if (state
== TASK_RUNNING
)
4570 printk(KERN_CONT
" running ");
4572 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4574 if (state
== TASK_RUNNING
)
4575 printk(KERN_CONT
" running task ");
4577 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4579 #ifdef CONFIG_DEBUG_STACK_USAGE
4580 free
= stack_not_used(p
);
4583 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
4585 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
4586 task_pid_nr(p
), ppid
,
4587 (unsigned long)task_thread_info(p
)->flags
);
4589 print_worker_info(KERN_INFO
, p
);
4590 show_stack(p
, NULL
);
4593 void show_state_filter(unsigned long state_filter
)
4595 struct task_struct
*g
, *p
;
4597 #if BITS_PER_LONG == 32
4599 " task PC stack pid father\n");
4602 " task PC stack pid father\n");
4605 do_each_thread(g
, p
) {
4607 * reset the NMI-timeout, listing all files on a slow
4608 * console might take a lot of time:
4610 touch_nmi_watchdog();
4611 if (!state_filter
|| (p
->state
& state_filter
))
4613 } while_each_thread(g
, p
);
4615 touch_all_softlockup_watchdogs();
4617 #ifdef CONFIG_SCHED_DEBUG
4618 sysrq_sched_debug_show();
4622 * Only show locks if all tasks are dumped:
4625 debug_show_all_locks();
4628 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4630 idle
->sched_class
= &idle_sched_class
;
4634 * init_idle - set up an idle thread for a given CPU
4635 * @idle: task in question
4636 * @cpu: cpu the idle task belongs to
4638 * NOTE: this function does not set the idle thread's NEED_RESCHED
4639 * flag, to make booting more robust.
4641 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4643 struct rq
*rq
= cpu_rq(cpu
);
4644 unsigned long flags
;
4646 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4649 idle
->state
= TASK_RUNNING
;
4650 idle
->se
.exec_start
= sched_clock();
4652 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
4654 * We're having a chicken and egg problem, even though we are
4655 * holding rq->lock, the cpu isn't yet set to this cpu so the
4656 * lockdep check in task_group() will fail.
4658 * Similar case to sched_fork(). / Alternatively we could
4659 * use task_rq_lock() here and obtain the other rq->lock.
4664 __set_task_cpu(idle
, cpu
);
4667 rq
->curr
= rq
->idle
= idle
;
4668 #if defined(CONFIG_SMP)
4671 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4673 /* Set the preempt count _outside_ the spinlocks! */
4674 task_thread_info(idle
)->preempt_count
= 0;
4677 * The idle tasks have their own, simple scheduling class:
4679 idle
->sched_class
= &idle_sched_class
;
4680 ftrace_graph_init_idle_task(idle
, cpu
);
4681 vtime_init_idle(idle
);
4682 #if defined(CONFIG_SMP)
4683 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
4688 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
4690 if (p
->sched_class
&& p
->sched_class
->set_cpus_allowed
)
4691 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
4693 cpumask_copy(&p
->cpus_allowed
, new_mask
);
4694 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
4698 * This is how migration works:
4700 * 1) we invoke migration_cpu_stop() on the target CPU using
4702 * 2) stopper starts to run (implicitly forcing the migrated thread
4704 * 3) it checks whether the migrated task is still in the wrong runqueue.
4705 * 4) if it's in the wrong runqueue then the migration thread removes
4706 * it and puts it into the right queue.
4707 * 5) stopper completes and stop_one_cpu() returns and the migration
4712 * Change a given task's CPU affinity. Migrate the thread to a
4713 * proper CPU and schedule it away if the CPU it's executing on
4714 * is removed from the allowed bitmask.
4716 * NOTE: the caller must have a valid reference to the task, the
4717 * task must not exit() & deallocate itself prematurely. The
4718 * call is not atomic; no spinlocks may be held.
4720 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
4722 unsigned long flags
;
4724 unsigned int dest_cpu
;
4727 rq
= task_rq_lock(p
, &flags
);
4729 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
4732 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
4737 do_set_cpus_allowed(p
, new_mask
);
4739 /* Can the task run on the task's current CPU? If so, we're done */
4740 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
4743 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
4745 struct migration_arg arg
= { p
, dest_cpu
};
4746 /* Need help from migration thread: drop lock and wait. */
4747 task_rq_unlock(rq
, p
, &flags
);
4748 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
4749 tlb_migrate_finish(p
->mm
);
4753 task_rq_unlock(rq
, p
, &flags
);
4757 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
4760 * Move (not current) task off this cpu, onto dest cpu. We're doing
4761 * this because either it can't run here any more (set_cpus_allowed()
4762 * away from this CPU, or CPU going down), or because we're
4763 * attempting to rebalance this task on exec (sched_exec).
4765 * So we race with normal scheduler movements, but that's OK, as long
4766 * as the task is no longer on this CPU.
4768 * Returns non-zero if task was successfully migrated.
4770 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4772 struct rq
*rq_dest
, *rq_src
;
4775 if (unlikely(!cpu_active(dest_cpu
)))
4778 rq_src
= cpu_rq(src_cpu
);
4779 rq_dest
= cpu_rq(dest_cpu
);
4781 raw_spin_lock(&p
->pi_lock
);
4782 double_rq_lock(rq_src
, rq_dest
);
4783 /* Already moved. */
4784 if (task_cpu(p
) != src_cpu
)
4786 /* Affinity changed (again). */
4787 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
4791 * If we're not on a rq, the next wake-up will ensure we're
4795 dequeue_task(rq_src
, p
, 0);
4796 set_task_cpu(p
, dest_cpu
);
4797 enqueue_task(rq_dest
, p
, 0);
4798 check_preempt_curr(rq_dest
, p
, 0);
4803 double_rq_unlock(rq_src
, rq_dest
);
4804 raw_spin_unlock(&p
->pi_lock
);
4809 * migration_cpu_stop - this will be executed by a highprio stopper thread
4810 * and performs thread migration by bumping thread off CPU then
4811 * 'pushing' onto another runqueue.
4813 static int migration_cpu_stop(void *data
)
4815 struct migration_arg
*arg
= data
;
4818 * The original target cpu might have gone down and we might
4819 * be on another cpu but it doesn't matter.
4821 local_irq_disable();
4822 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
4827 #ifdef CONFIG_HOTPLUG_CPU
4830 * Ensures that the idle task is using init_mm right before its cpu goes
4833 void idle_task_exit(void)
4835 struct mm_struct
*mm
= current
->active_mm
;
4837 BUG_ON(cpu_online(smp_processor_id()));
4840 switch_mm(mm
, &init_mm
, current
);
4845 * Since this CPU is going 'away' for a while, fold any nr_active delta
4846 * we might have. Assumes we're called after migrate_tasks() so that the
4847 * nr_active count is stable.
4849 * Also see the comment "Global load-average calculations".
4851 static void calc_load_migrate(struct rq
*rq
)
4853 long delta
= calc_load_fold_active(rq
);
4855 atomic_long_add(delta
, &calc_load_tasks
);
4859 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4860 * try_to_wake_up()->select_task_rq().
4862 * Called with rq->lock held even though we'er in stop_machine() and
4863 * there's no concurrency possible, we hold the required locks anyway
4864 * because of lock validation efforts.
4866 static void migrate_tasks(unsigned int dead_cpu
)
4868 struct rq
*rq
= cpu_rq(dead_cpu
);
4869 struct task_struct
*next
, *stop
= rq
->stop
;
4873 * Fudge the rq selection such that the below task selection loop
4874 * doesn't get stuck on the currently eligible stop task.
4876 * We're currently inside stop_machine() and the rq is either stuck
4877 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4878 * either way we should never end up calling schedule() until we're
4885 * There's this thread running, bail when that's the only
4888 if (rq
->nr_running
== 1)
4891 next
= pick_next_task(rq
);
4893 next
->sched_class
->put_prev_task(rq
, next
);
4895 /* Find suitable destination for @next, with force if needed. */
4896 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
4897 raw_spin_unlock(&rq
->lock
);
4899 __migrate_task(next
, dead_cpu
, dest_cpu
);
4901 raw_spin_lock(&rq
->lock
);
4907 #endif /* CONFIG_HOTPLUG_CPU */
4909 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4911 static struct ctl_table sd_ctl_dir
[] = {
4913 .procname
= "sched_domain",
4919 static struct ctl_table sd_ctl_root
[] = {
4921 .procname
= "kernel",
4923 .child
= sd_ctl_dir
,
4928 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
4930 struct ctl_table
*entry
=
4931 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
4936 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
4938 struct ctl_table
*entry
;
4941 * In the intermediate directories, both the child directory and
4942 * procname are dynamically allocated and could fail but the mode
4943 * will always be set. In the lowest directory the names are
4944 * static strings and all have proc handlers.
4946 for (entry
= *tablep
; entry
->mode
; entry
++) {
4948 sd_free_ctl_entry(&entry
->child
);
4949 if (entry
->proc_handler
== NULL
)
4950 kfree(entry
->procname
);
4957 static int min_load_idx
= 0;
4958 static int max_load_idx
= CPU_LOAD_IDX_MAX
-1;
4961 set_table_entry(struct ctl_table
*entry
,
4962 const char *procname
, void *data
, int maxlen
,
4963 umode_t mode
, proc_handler
*proc_handler
,
4966 entry
->procname
= procname
;
4968 entry
->maxlen
= maxlen
;
4970 entry
->proc_handler
= proc_handler
;
4973 entry
->extra1
= &min_load_idx
;
4974 entry
->extra2
= &max_load_idx
;
4978 static struct ctl_table
*
4979 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
4981 struct ctl_table
*table
= sd_alloc_ctl_entry(13);
4986 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
4987 sizeof(long), 0644, proc_doulongvec_minmax
, false);
4988 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
4989 sizeof(long), 0644, proc_doulongvec_minmax
, false);
4990 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
4991 sizeof(int), 0644, proc_dointvec_minmax
, true);
4992 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
4993 sizeof(int), 0644, proc_dointvec_minmax
, true);
4994 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
4995 sizeof(int), 0644, proc_dointvec_minmax
, true);
4996 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
4997 sizeof(int), 0644, proc_dointvec_minmax
, true);
4998 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
4999 sizeof(int), 0644, proc_dointvec_minmax
, true);
5000 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5001 sizeof(int), 0644, proc_dointvec_minmax
, false);
5002 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5003 sizeof(int), 0644, proc_dointvec_minmax
, false);
5004 set_table_entry(&table
[9], "cache_nice_tries",
5005 &sd
->cache_nice_tries
,
5006 sizeof(int), 0644, proc_dointvec_minmax
, false);
5007 set_table_entry(&table
[10], "flags", &sd
->flags
,
5008 sizeof(int), 0644, proc_dointvec_minmax
, false);
5009 set_table_entry(&table
[11], "name", sd
->name
,
5010 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
5011 /* &table[12] is terminator */
5016 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5018 struct ctl_table
*entry
, *table
;
5019 struct sched_domain
*sd
;
5020 int domain_num
= 0, i
;
5023 for_each_domain(cpu
, sd
)
5025 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5030 for_each_domain(cpu
, sd
) {
5031 snprintf(buf
, 32, "domain%d", i
);
5032 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5034 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5041 static struct ctl_table_header
*sd_sysctl_header
;
5042 static void register_sched_domain_sysctl(void)
5044 int i
, cpu_num
= num_possible_cpus();
5045 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5048 WARN_ON(sd_ctl_dir
[0].child
);
5049 sd_ctl_dir
[0].child
= entry
;
5054 for_each_possible_cpu(i
) {
5055 snprintf(buf
, 32, "cpu%d", i
);
5056 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5058 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5062 WARN_ON(sd_sysctl_header
);
5063 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5066 /* may be called multiple times per register */
5067 static void unregister_sched_domain_sysctl(void)
5069 if (sd_sysctl_header
)
5070 unregister_sysctl_table(sd_sysctl_header
);
5071 sd_sysctl_header
= NULL
;
5072 if (sd_ctl_dir
[0].child
)
5073 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5076 static void register_sched_domain_sysctl(void)
5079 static void unregister_sched_domain_sysctl(void)
5084 static void set_rq_online(struct rq
*rq
)
5087 const struct sched_class
*class;
5089 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5092 for_each_class(class) {
5093 if (class->rq_online
)
5094 class->rq_online(rq
);
5099 static void set_rq_offline(struct rq
*rq
)
5102 const struct sched_class
*class;
5104 for_each_class(class) {
5105 if (class->rq_offline
)
5106 class->rq_offline(rq
);
5109 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5115 * migration_call - callback that gets triggered when a CPU is added.
5116 * Here we can start up the necessary migration thread for the new CPU.
5118 static int __cpuinit
5119 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5121 int cpu
= (long)hcpu
;
5122 unsigned long flags
;
5123 struct rq
*rq
= cpu_rq(cpu
);
5125 switch (action
& ~CPU_TASKS_FROZEN
) {
5127 case CPU_UP_PREPARE
:
5128 rq
->calc_load_update
= calc_load_update
;
5132 /* Update our root-domain */
5133 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5135 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5139 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5142 #ifdef CONFIG_HOTPLUG_CPU
5144 sched_ttwu_pending();
5145 /* Update our root-domain */
5146 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5148 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5152 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
5153 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5157 calc_load_migrate(rq
);
5162 update_max_interval();
5168 * Register at high priority so that task migration (migrate_all_tasks)
5169 * happens before everything else. This has to be lower priority than
5170 * the notifier in the perf_event subsystem, though.
5172 static struct notifier_block __cpuinitdata migration_notifier
= {
5173 .notifier_call
= migration_call
,
5174 .priority
= CPU_PRI_MIGRATION
,
5177 static int __cpuinit
sched_cpu_active(struct notifier_block
*nfb
,
5178 unsigned long action
, void *hcpu
)
5180 switch (action
& ~CPU_TASKS_FROZEN
) {
5182 case CPU_DOWN_FAILED
:
5183 set_cpu_active((long)hcpu
, true);
5190 static int __cpuinit
sched_cpu_inactive(struct notifier_block
*nfb
,
5191 unsigned long action
, void *hcpu
)
5193 switch (action
& ~CPU_TASKS_FROZEN
) {
5194 case CPU_DOWN_PREPARE
:
5195 set_cpu_active((long)hcpu
, false);
5202 static int __init
migration_init(void)
5204 void *cpu
= (void *)(long)smp_processor_id();
5207 /* Initialize migration for the boot CPU */
5208 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5209 BUG_ON(err
== NOTIFY_BAD
);
5210 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5211 register_cpu_notifier(&migration_notifier
);
5213 /* Register cpu active notifiers */
5214 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
5215 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
5219 early_initcall(migration_init
);
5224 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5226 #ifdef CONFIG_SCHED_DEBUG
5228 static __read_mostly
int sched_debug_enabled
;
5230 static int __init
sched_debug_setup(char *str
)
5232 sched_debug_enabled
= 1;
5236 early_param("sched_debug", sched_debug_setup
);
5238 static inline bool sched_debug(void)
5240 return sched_debug_enabled
;
5243 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5244 struct cpumask
*groupmask
)
5246 struct sched_group
*group
= sd
->groups
;
5249 cpulist_scnprintf(str
, sizeof(str
), sched_domain_span(sd
));
5250 cpumask_clear(groupmask
);
5252 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5254 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5255 printk("does not load-balance\n");
5257 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5262 printk(KERN_CONT
"span %s level %s\n", str
, sd
->name
);
5264 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5265 printk(KERN_ERR
"ERROR: domain->span does not contain "
5268 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5269 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5273 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5277 printk(KERN_ERR
"ERROR: group is NULL\n");
5282 * Even though we initialize ->power to something semi-sane,
5283 * we leave power_orig unset. This allows us to detect if
5284 * domain iteration is still funny without causing /0 traps.
5286 if (!group
->sgp
->power_orig
) {
5287 printk(KERN_CONT
"\n");
5288 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5293 if (!cpumask_weight(sched_group_cpus(group
))) {
5294 printk(KERN_CONT
"\n");
5295 printk(KERN_ERR
"ERROR: empty group\n");
5299 if (!(sd
->flags
& SD_OVERLAP
) &&
5300 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5301 printk(KERN_CONT
"\n");
5302 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5306 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5308 cpulist_scnprintf(str
, sizeof(str
), sched_group_cpus(group
));
5310 printk(KERN_CONT
" %s", str
);
5311 if (group
->sgp
->power
!= SCHED_POWER_SCALE
) {
5312 printk(KERN_CONT
" (cpu_power = %d)",
5316 group
= group
->next
;
5317 } while (group
!= sd
->groups
);
5318 printk(KERN_CONT
"\n");
5320 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5321 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5324 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5325 printk(KERN_ERR
"ERROR: parent span is not a superset "
5326 "of domain->span\n");
5330 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5334 if (!sched_debug_enabled
)
5338 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5342 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5345 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5353 #else /* !CONFIG_SCHED_DEBUG */
5354 # define sched_domain_debug(sd, cpu) do { } while (0)
5355 static inline bool sched_debug(void)
5359 #endif /* CONFIG_SCHED_DEBUG */
5361 static int sd_degenerate(struct sched_domain
*sd
)
5363 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5366 /* Following flags need at least 2 groups */
5367 if (sd
->flags
& (SD_LOAD_BALANCE
|
5368 SD_BALANCE_NEWIDLE
|
5372 SD_SHARE_PKG_RESOURCES
)) {
5373 if (sd
->groups
!= sd
->groups
->next
)
5377 /* Following flags don't use groups */
5378 if (sd
->flags
& (SD_WAKE_AFFINE
))
5385 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5387 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5389 if (sd_degenerate(parent
))
5392 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5395 /* Flags needing groups don't count if only 1 group in parent */
5396 if (parent
->groups
== parent
->groups
->next
) {
5397 pflags
&= ~(SD_LOAD_BALANCE
|
5398 SD_BALANCE_NEWIDLE
|
5402 SD_SHARE_PKG_RESOURCES
);
5403 if (nr_node_ids
== 1)
5404 pflags
&= ~SD_SERIALIZE
;
5406 if (~cflags
& pflags
)
5412 static void free_rootdomain(struct rcu_head
*rcu
)
5414 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5416 cpupri_cleanup(&rd
->cpupri
);
5417 free_cpumask_var(rd
->rto_mask
);
5418 free_cpumask_var(rd
->online
);
5419 free_cpumask_var(rd
->span
);
5423 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5425 struct root_domain
*old_rd
= NULL
;
5426 unsigned long flags
;
5428 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5433 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5436 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5439 * If we dont want to free the old_rt yet then
5440 * set old_rd to NULL to skip the freeing later
5443 if (!atomic_dec_and_test(&old_rd
->refcount
))
5447 atomic_inc(&rd
->refcount
);
5450 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5451 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5454 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5457 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5460 static int init_rootdomain(struct root_domain
*rd
)
5462 memset(rd
, 0, sizeof(*rd
));
5464 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5466 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5468 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5471 if (cpupri_init(&rd
->cpupri
) != 0)
5476 free_cpumask_var(rd
->rto_mask
);
5478 free_cpumask_var(rd
->online
);
5480 free_cpumask_var(rd
->span
);
5486 * By default the system creates a single root-domain with all cpus as
5487 * members (mimicking the global state we have today).
5489 struct root_domain def_root_domain
;
5491 static void init_defrootdomain(void)
5493 init_rootdomain(&def_root_domain
);
5495 atomic_set(&def_root_domain
.refcount
, 1);
5498 static struct root_domain
*alloc_rootdomain(void)
5500 struct root_domain
*rd
;
5502 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
5506 if (init_rootdomain(rd
) != 0) {
5514 static void free_sched_groups(struct sched_group
*sg
, int free_sgp
)
5516 struct sched_group
*tmp
, *first
;
5525 if (free_sgp
&& atomic_dec_and_test(&sg
->sgp
->ref
))
5530 } while (sg
!= first
);
5533 static void free_sched_domain(struct rcu_head
*rcu
)
5535 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
5538 * If its an overlapping domain it has private groups, iterate and
5541 if (sd
->flags
& SD_OVERLAP
) {
5542 free_sched_groups(sd
->groups
, 1);
5543 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
5544 kfree(sd
->groups
->sgp
);
5550 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
5552 call_rcu(&sd
->rcu
, free_sched_domain
);
5555 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
5557 for (; sd
; sd
= sd
->parent
)
5558 destroy_sched_domain(sd
, cpu
);
5562 * Keep a special pointer to the highest sched_domain that has
5563 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5564 * allows us to avoid some pointer chasing select_idle_sibling().
5566 * Also keep a unique ID per domain (we use the first cpu number in
5567 * the cpumask of the domain), this allows us to quickly tell if
5568 * two cpus are in the same cache domain, see cpus_share_cache().
5570 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
5571 DEFINE_PER_CPU(int, sd_llc_id
);
5573 static void update_top_cache_domain(int cpu
)
5575 struct sched_domain
*sd
;
5578 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
5580 id
= cpumask_first(sched_domain_span(sd
));
5582 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
5583 per_cpu(sd_llc_id
, cpu
) = id
;
5587 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5588 * hold the hotplug lock.
5591 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
5593 struct rq
*rq
= cpu_rq(cpu
);
5594 struct sched_domain
*tmp
;
5596 /* Remove the sched domains which do not contribute to scheduling. */
5597 for (tmp
= sd
; tmp
; ) {
5598 struct sched_domain
*parent
= tmp
->parent
;
5602 if (sd_parent_degenerate(tmp
, parent
)) {
5603 tmp
->parent
= parent
->parent
;
5605 parent
->parent
->child
= tmp
;
5606 destroy_sched_domain(parent
, cpu
);
5611 if (sd
&& sd_degenerate(sd
)) {
5614 destroy_sched_domain(tmp
, cpu
);
5619 sched_domain_debug(sd
, cpu
);
5621 rq_attach_root(rq
, rd
);
5623 rcu_assign_pointer(rq
->sd
, sd
);
5624 destroy_sched_domains(tmp
, cpu
);
5626 update_top_cache_domain(cpu
);
5629 /* cpus with isolated domains */
5630 static cpumask_var_t cpu_isolated_map
;
5632 /* Setup the mask of cpus configured for isolated domains */
5633 static int __init
isolated_cpu_setup(char *str
)
5635 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
5636 cpulist_parse(str
, cpu_isolated_map
);
5640 __setup("isolcpus=", isolated_cpu_setup
);
5642 static const struct cpumask
*cpu_cpu_mask(int cpu
)
5644 return cpumask_of_node(cpu_to_node(cpu
));
5648 struct sched_domain
**__percpu sd
;
5649 struct sched_group
**__percpu sg
;
5650 struct sched_group_power
**__percpu sgp
;
5654 struct sched_domain
** __percpu sd
;
5655 struct root_domain
*rd
;
5665 struct sched_domain_topology_level
;
5667 typedef struct sched_domain
*(*sched_domain_init_f
)(struct sched_domain_topology_level
*tl
, int cpu
);
5668 typedef const struct cpumask
*(*sched_domain_mask_f
)(int cpu
);
5670 #define SDTL_OVERLAP 0x01
5672 struct sched_domain_topology_level
{
5673 sched_domain_init_f init
;
5674 sched_domain_mask_f mask
;
5677 struct sd_data data
;
5681 * Build an iteration mask that can exclude certain CPUs from the upwards
5684 * Asymmetric node setups can result in situations where the domain tree is of
5685 * unequal depth, make sure to skip domains that already cover the entire
5688 * In that case build_sched_domains() will have terminated the iteration early
5689 * and our sibling sd spans will be empty. Domains should always include the
5690 * cpu they're built on, so check that.
5693 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
5695 const struct cpumask
*span
= sched_domain_span(sd
);
5696 struct sd_data
*sdd
= sd
->private;
5697 struct sched_domain
*sibling
;
5700 for_each_cpu(i
, span
) {
5701 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5702 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5705 cpumask_set_cpu(i
, sched_group_mask(sg
));
5710 * Return the canonical balance cpu for this group, this is the first cpu
5711 * of this group that's also in the iteration mask.
5713 int group_balance_cpu(struct sched_group
*sg
)
5715 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
5719 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
5721 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
5722 const struct cpumask
*span
= sched_domain_span(sd
);
5723 struct cpumask
*covered
= sched_domains_tmpmask
;
5724 struct sd_data
*sdd
= sd
->private;
5725 struct sched_domain
*child
;
5728 cpumask_clear(covered
);
5730 for_each_cpu(i
, span
) {
5731 struct cpumask
*sg_span
;
5733 if (cpumask_test_cpu(i
, covered
))
5736 child
= *per_cpu_ptr(sdd
->sd
, i
);
5738 /* See the comment near build_group_mask(). */
5739 if (!cpumask_test_cpu(i
, sched_domain_span(child
)))
5742 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5743 GFP_KERNEL
, cpu_to_node(cpu
));
5748 sg_span
= sched_group_cpus(sg
);
5750 child
= child
->child
;
5751 cpumask_copy(sg_span
, sched_domain_span(child
));
5753 cpumask_set_cpu(i
, sg_span
);
5755 cpumask_or(covered
, covered
, sg_span
);
5757 sg
->sgp
= *per_cpu_ptr(sdd
->sgp
, i
);
5758 if (atomic_inc_return(&sg
->sgp
->ref
) == 1)
5759 build_group_mask(sd
, sg
);
5762 * Initialize sgp->power such that even if we mess up the
5763 * domains and no possible iteration will get us here, we won't
5766 sg
->sgp
->power
= SCHED_POWER_SCALE
* cpumask_weight(sg_span
);
5769 * Make sure the first group of this domain contains the
5770 * canonical balance cpu. Otherwise the sched_domain iteration
5771 * breaks. See update_sg_lb_stats().
5773 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
5774 group_balance_cpu(sg
) == cpu
)
5784 sd
->groups
= groups
;
5789 free_sched_groups(first
, 0);
5794 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
5796 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
5797 struct sched_domain
*child
= sd
->child
;
5800 cpu
= cpumask_first(sched_domain_span(child
));
5803 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
5804 (*sg
)->sgp
= *per_cpu_ptr(sdd
->sgp
, cpu
);
5805 atomic_set(&(*sg
)->sgp
->ref
, 1); /* for claim_allocations */
5812 * build_sched_groups will build a circular linked list of the groups
5813 * covered by the given span, and will set each group's ->cpumask correctly,
5814 * and ->cpu_power to 0.
5816 * Assumes the sched_domain tree is fully constructed
5819 build_sched_groups(struct sched_domain
*sd
, int cpu
)
5821 struct sched_group
*first
= NULL
, *last
= NULL
;
5822 struct sd_data
*sdd
= sd
->private;
5823 const struct cpumask
*span
= sched_domain_span(sd
);
5824 struct cpumask
*covered
;
5827 get_group(cpu
, sdd
, &sd
->groups
);
5828 atomic_inc(&sd
->groups
->ref
);
5830 if (cpu
!= cpumask_first(sched_domain_span(sd
)))
5833 lockdep_assert_held(&sched_domains_mutex
);
5834 covered
= sched_domains_tmpmask
;
5836 cpumask_clear(covered
);
5838 for_each_cpu(i
, span
) {
5839 struct sched_group
*sg
;
5840 int group
= get_group(i
, sdd
, &sg
);
5843 if (cpumask_test_cpu(i
, covered
))
5846 cpumask_clear(sched_group_cpus(sg
));
5848 cpumask_setall(sched_group_mask(sg
));
5850 for_each_cpu(j
, span
) {
5851 if (get_group(j
, sdd
, NULL
) != group
)
5854 cpumask_set_cpu(j
, covered
);
5855 cpumask_set_cpu(j
, sched_group_cpus(sg
));
5870 * Initialize sched groups cpu_power.
5872 * cpu_power indicates the capacity of sched group, which is used while
5873 * distributing the load between different sched groups in a sched domain.
5874 * Typically cpu_power for all the groups in a sched domain will be same unless
5875 * there are asymmetries in the topology. If there are asymmetries, group
5876 * having more cpu_power will pickup more load compared to the group having
5879 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5881 struct sched_group
*sg
= sd
->groups
;
5883 WARN_ON(!sd
|| !sg
);
5886 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
5888 } while (sg
!= sd
->groups
);
5890 if (cpu
!= group_balance_cpu(sg
))
5893 update_group_power(sd
, cpu
);
5894 atomic_set(&sg
->sgp
->nr_busy_cpus
, sg
->group_weight
);
5897 int __weak
arch_sd_sibling_asym_packing(void)
5899 return 0*SD_ASYM_PACKING
;
5903 * Initializers for schedule domains
5904 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5907 #ifdef CONFIG_SCHED_DEBUG
5908 # define SD_INIT_NAME(sd, type) sd->name = #type
5910 # define SD_INIT_NAME(sd, type) do { } while (0)
5913 #define SD_INIT_FUNC(type) \
5914 static noinline struct sched_domain * \
5915 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5917 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5918 *sd = SD_##type##_INIT; \
5919 SD_INIT_NAME(sd, type); \
5920 sd->private = &tl->data; \
5925 #ifdef CONFIG_SCHED_SMT
5926 SD_INIT_FUNC(SIBLING
)
5928 #ifdef CONFIG_SCHED_MC
5931 #ifdef CONFIG_SCHED_BOOK
5935 static int default_relax_domain_level
= -1;
5936 int sched_domain_level_max
;
5938 static int __init
setup_relax_domain_level(char *str
)
5940 if (kstrtoint(str
, 0, &default_relax_domain_level
))
5941 pr_warn("Unable to set relax_domain_level\n");
5945 __setup("relax_domain_level=", setup_relax_domain_level
);
5947 static void set_domain_attribute(struct sched_domain
*sd
,
5948 struct sched_domain_attr
*attr
)
5952 if (!attr
|| attr
->relax_domain_level
< 0) {
5953 if (default_relax_domain_level
< 0)
5956 request
= default_relax_domain_level
;
5958 request
= attr
->relax_domain_level
;
5959 if (request
< sd
->level
) {
5960 /* turn off idle balance on this domain */
5961 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5963 /* turn on idle balance on this domain */
5964 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5968 static void __sdt_free(const struct cpumask
*cpu_map
);
5969 static int __sdt_alloc(const struct cpumask
*cpu_map
);
5971 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
5972 const struct cpumask
*cpu_map
)
5976 if (!atomic_read(&d
->rd
->refcount
))
5977 free_rootdomain(&d
->rd
->rcu
); /* fall through */
5979 free_percpu(d
->sd
); /* fall through */
5981 __sdt_free(cpu_map
); /* fall through */
5987 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
5988 const struct cpumask
*cpu_map
)
5990 memset(d
, 0, sizeof(*d
));
5992 if (__sdt_alloc(cpu_map
))
5993 return sa_sd_storage
;
5994 d
->sd
= alloc_percpu(struct sched_domain
*);
5996 return sa_sd_storage
;
5997 d
->rd
= alloc_rootdomain();
6000 return sa_rootdomain
;
6004 * NULL the sd_data elements we've used to build the sched_domain and
6005 * sched_group structure so that the subsequent __free_domain_allocs()
6006 * will not free the data we're using.
6008 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6010 struct sd_data
*sdd
= sd
->private;
6012 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6013 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6015 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6016 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6018 if (atomic_read(&(*per_cpu_ptr(sdd
->sgp
, cpu
))->ref
))
6019 *per_cpu_ptr(sdd
->sgp
, cpu
) = NULL
;
6022 #ifdef CONFIG_SCHED_SMT
6023 static const struct cpumask
*cpu_smt_mask(int cpu
)
6025 return topology_thread_cpumask(cpu
);
6030 * Topology list, bottom-up.
6032 static struct sched_domain_topology_level default_topology
[] = {
6033 #ifdef CONFIG_SCHED_SMT
6034 { sd_init_SIBLING
, cpu_smt_mask
, },
6036 #ifdef CONFIG_SCHED_MC
6037 { sd_init_MC
, cpu_coregroup_mask
, },
6039 #ifdef CONFIG_SCHED_BOOK
6040 { sd_init_BOOK
, cpu_book_mask
, },
6042 { sd_init_CPU
, cpu_cpu_mask
, },
6046 static struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
6050 static int sched_domains_numa_levels
;
6051 static int *sched_domains_numa_distance
;
6052 static struct cpumask
***sched_domains_numa_masks
;
6053 static int sched_domains_curr_level
;
6055 static inline int sd_local_flags(int level
)
6057 if (sched_domains_numa_distance
[level
] > RECLAIM_DISTANCE
)
6060 return SD_BALANCE_EXEC
| SD_BALANCE_FORK
| SD_WAKE_AFFINE
;
6063 static struct sched_domain
*
6064 sd_numa_init(struct sched_domain_topology_level
*tl
, int cpu
)
6066 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6067 int level
= tl
->numa_level
;
6068 int sd_weight
= cpumask_weight(
6069 sched_domains_numa_masks
[level
][cpu_to_node(cpu
)]);
6071 *sd
= (struct sched_domain
){
6072 .min_interval
= sd_weight
,
6073 .max_interval
= 2*sd_weight
,
6075 .imbalance_pct
= 125,
6076 .cache_nice_tries
= 2,
6083 .flags
= 1*SD_LOAD_BALANCE
6084 | 1*SD_BALANCE_NEWIDLE
6089 | 0*SD_SHARE_CPUPOWER
6090 | 0*SD_SHARE_PKG_RESOURCES
6092 | 0*SD_PREFER_SIBLING
6093 | sd_local_flags(level
)
6095 .last_balance
= jiffies
,
6096 .balance_interval
= sd_weight
,
6098 SD_INIT_NAME(sd
, NUMA
);
6099 sd
->private = &tl
->data
;
6102 * Ugly hack to pass state to sd_numa_mask()...
6104 sched_domains_curr_level
= tl
->numa_level
;
6109 static const struct cpumask
*sd_numa_mask(int cpu
)
6111 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6114 static void sched_numa_warn(const char *str
)
6116 static int done
= false;
6124 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6126 for (i
= 0; i
< nr_node_ids
; i
++) {
6127 printk(KERN_WARNING
" ");
6128 for (j
= 0; j
< nr_node_ids
; j
++)
6129 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6130 printk(KERN_CONT
"\n");
6132 printk(KERN_WARNING
"\n");
6135 static bool find_numa_distance(int distance
)
6139 if (distance
== node_distance(0, 0))
6142 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6143 if (sched_domains_numa_distance
[i
] == distance
)
6150 static void sched_init_numa(void)
6152 int next_distance
, curr_distance
= node_distance(0, 0);
6153 struct sched_domain_topology_level
*tl
;
6157 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6158 if (!sched_domains_numa_distance
)
6162 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6163 * unique distances in the node_distance() table.
6165 * Assumes node_distance(0,j) includes all distances in
6166 * node_distance(i,j) in order to avoid cubic time.
6168 next_distance
= curr_distance
;
6169 for (i
= 0; i
< nr_node_ids
; i
++) {
6170 for (j
= 0; j
< nr_node_ids
; j
++) {
6171 for (k
= 0; k
< nr_node_ids
; k
++) {
6172 int distance
= node_distance(i
, k
);
6174 if (distance
> curr_distance
&&
6175 (distance
< next_distance
||
6176 next_distance
== curr_distance
))
6177 next_distance
= distance
;
6180 * While not a strong assumption it would be nice to know
6181 * about cases where if node A is connected to B, B is not
6182 * equally connected to A.
6184 if (sched_debug() && node_distance(k
, i
) != distance
)
6185 sched_numa_warn("Node-distance not symmetric");
6187 if (sched_debug() && i
&& !find_numa_distance(distance
))
6188 sched_numa_warn("Node-0 not representative");
6190 if (next_distance
!= curr_distance
) {
6191 sched_domains_numa_distance
[level
++] = next_distance
;
6192 sched_domains_numa_levels
= level
;
6193 curr_distance
= next_distance
;
6198 * In case of sched_debug() we verify the above assumption.
6204 * 'level' contains the number of unique distances, excluding the
6205 * identity distance node_distance(i,i).
6207 * The sched_domains_numa_distance[] array includes the actual distance
6212 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6213 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6214 * the array will contain less then 'level' members. This could be
6215 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6216 * in other functions.
6218 * We reset it to 'level' at the end of this function.
6220 sched_domains_numa_levels
= 0;
6222 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6223 if (!sched_domains_numa_masks
)
6227 * Now for each level, construct a mask per node which contains all
6228 * cpus of nodes that are that many hops away from us.
6230 for (i
= 0; i
< level
; i
++) {
6231 sched_domains_numa_masks
[i
] =
6232 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6233 if (!sched_domains_numa_masks
[i
])
6236 for (j
= 0; j
< nr_node_ids
; j
++) {
6237 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6241 sched_domains_numa_masks
[i
][j
] = mask
;
6243 for (k
= 0; k
< nr_node_ids
; k
++) {
6244 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6247 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6252 tl
= kzalloc((ARRAY_SIZE(default_topology
) + level
) *
6253 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6258 * Copy the default topology bits..
6260 for (i
= 0; default_topology
[i
].init
; i
++)
6261 tl
[i
] = default_topology
[i
];
6264 * .. and append 'j' levels of NUMA goodness.
6266 for (j
= 0; j
< level
; i
++, j
++) {
6267 tl
[i
] = (struct sched_domain_topology_level
){
6268 .init
= sd_numa_init
,
6269 .mask
= sd_numa_mask
,
6270 .flags
= SDTL_OVERLAP
,
6275 sched_domain_topology
= tl
;
6277 sched_domains_numa_levels
= level
;
6280 static void sched_domains_numa_masks_set(int cpu
)
6283 int node
= cpu_to_node(cpu
);
6285 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6286 for (j
= 0; j
< nr_node_ids
; j
++) {
6287 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6288 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6293 static void sched_domains_numa_masks_clear(int cpu
)
6296 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6297 for (j
= 0; j
< nr_node_ids
; j
++)
6298 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6303 * Update sched_domains_numa_masks[level][node] array when new cpus
6306 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6307 unsigned long action
,
6310 int cpu
= (long)hcpu
;
6312 switch (action
& ~CPU_TASKS_FROZEN
) {
6314 sched_domains_numa_masks_set(cpu
);
6318 sched_domains_numa_masks_clear(cpu
);
6328 static inline void sched_init_numa(void)
6332 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6333 unsigned long action
,
6338 #endif /* CONFIG_NUMA */
6340 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6342 struct sched_domain_topology_level
*tl
;
6345 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6346 struct sd_data
*sdd
= &tl
->data
;
6348 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6352 sdd
->sg
= alloc_percpu(struct sched_group
*);
6356 sdd
->sgp
= alloc_percpu(struct sched_group_power
*);
6360 for_each_cpu(j
, cpu_map
) {
6361 struct sched_domain
*sd
;
6362 struct sched_group
*sg
;
6363 struct sched_group_power
*sgp
;
6365 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6366 GFP_KERNEL
, cpu_to_node(j
));
6370 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6372 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6373 GFP_KERNEL
, cpu_to_node(j
));
6379 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6381 sgp
= kzalloc_node(sizeof(struct sched_group_power
) + cpumask_size(),
6382 GFP_KERNEL
, cpu_to_node(j
));
6386 *per_cpu_ptr(sdd
->sgp
, j
) = sgp
;
6393 static void __sdt_free(const struct cpumask
*cpu_map
)
6395 struct sched_domain_topology_level
*tl
;
6398 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6399 struct sd_data
*sdd
= &tl
->data
;
6401 for_each_cpu(j
, cpu_map
) {
6402 struct sched_domain
*sd
;
6405 sd
= *per_cpu_ptr(sdd
->sd
, j
);
6406 if (sd
&& (sd
->flags
& SD_OVERLAP
))
6407 free_sched_groups(sd
->groups
, 0);
6408 kfree(*per_cpu_ptr(sdd
->sd
, j
));
6412 kfree(*per_cpu_ptr(sdd
->sg
, j
));
6414 kfree(*per_cpu_ptr(sdd
->sgp
, j
));
6416 free_percpu(sdd
->sd
);
6418 free_percpu(sdd
->sg
);
6420 free_percpu(sdd
->sgp
);
6425 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
6426 struct s_data
*d
, const struct cpumask
*cpu_map
,
6427 struct sched_domain_attr
*attr
, struct sched_domain
*child
,
6430 struct sched_domain
*sd
= tl
->init(tl
, cpu
);
6434 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
6436 sd
->level
= child
->level
+ 1;
6437 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
6441 set_domain_attribute(sd
, attr
);
6447 * Build sched domains for a given set of cpus and attach the sched domains
6448 * to the individual cpus
6450 static int build_sched_domains(const struct cpumask
*cpu_map
,
6451 struct sched_domain_attr
*attr
)
6453 enum s_alloc alloc_state
= sa_none
;
6454 struct sched_domain
*sd
;
6456 int i
, ret
= -ENOMEM
;
6458 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
6459 if (alloc_state
!= sa_rootdomain
)
6462 /* Set up domains for cpus specified by the cpu_map. */
6463 for_each_cpu(i
, cpu_map
) {
6464 struct sched_domain_topology_level
*tl
;
6467 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6468 sd
= build_sched_domain(tl
, &d
, cpu_map
, attr
, sd
, i
);
6469 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
6470 sd
->flags
|= SD_OVERLAP
;
6471 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
6478 *per_cpu_ptr(d
.sd
, i
) = sd
;
6481 /* Build the groups for the domains */
6482 for_each_cpu(i
, cpu_map
) {
6483 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6484 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
6485 if (sd
->flags
& SD_OVERLAP
) {
6486 if (build_overlap_sched_groups(sd
, i
))
6489 if (build_sched_groups(sd
, i
))
6495 /* Calculate CPU power for physical packages and nodes */
6496 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
6497 if (!cpumask_test_cpu(i
, cpu_map
))
6500 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6501 claim_allocations(i
, sd
);
6502 init_sched_groups_power(i
, sd
);
6506 /* Attach the domains */
6508 for_each_cpu(i
, cpu_map
) {
6509 sd
= *per_cpu_ptr(d
.sd
, i
);
6510 cpu_attach_domain(sd
, d
.rd
, i
);
6516 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
6520 static cpumask_var_t
*doms_cur
; /* current sched domains */
6521 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6522 static struct sched_domain_attr
*dattr_cur
;
6523 /* attribues of custom domains in 'doms_cur' */
6526 * Special case: If a kmalloc of a doms_cur partition (array of
6527 * cpumask) fails, then fallback to a single sched domain,
6528 * as determined by the single cpumask fallback_doms.
6530 static cpumask_var_t fallback_doms
;
6533 * arch_update_cpu_topology lets virtualized architectures update the
6534 * cpu core maps. It is supposed to return 1 if the topology changed
6535 * or 0 if it stayed the same.
6537 int __attribute__((weak
)) arch_update_cpu_topology(void)
6542 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
6545 cpumask_var_t
*doms
;
6547 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
6550 for (i
= 0; i
< ndoms
; i
++) {
6551 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
6552 free_sched_domains(doms
, i
);
6559 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
6562 for (i
= 0; i
< ndoms
; i
++)
6563 free_cpumask_var(doms
[i
]);
6568 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6569 * For now this just excludes isolated cpus, but could be used to
6570 * exclude other special cases in the future.
6572 static int init_sched_domains(const struct cpumask
*cpu_map
)
6576 arch_update_cpu_topology();
6578 doms_cur
= alloc_sched_domains(ndoms_cur
);
6580 doms_cur
= &fallback_doms
;
6581 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
6582 err
= build_sched_domains(doms_cur
[0], NULL
);
6583 register_sched_domain_sysctl();
6589 * Detach sched domains from a group of cpus specified in cpu_map
6590 * These cpus will now be attached to the NULL domain
6592 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
6597 for_each_cpu(i
, cpu_map
)
6598 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6602 /* handle null as "default" */
6603 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
6604 struct sched_domain_attr
*new, int idx_new
)
6606 struct sched_domain_attr tmp
;
6613 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
6614 new ? (new + idx_new
) : &tmp
,
6615 sizeof(struct sched_domain_attr
));
6619 * Partition sched domains as specified by the 'ndoms_new'
6620 * cpumasks in the array doms_new[] of cpumasks. This compares
6621 * doms_new[] to the current sched domain partitioning, doms_cur[].
6622 * It destroys each deleted domain and builds each new domain.
6624 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6625 * The masks don't intersect (don't overlap.) We should setup one
6626 * sched domain for each mask. CPUs not in any of the cpumasks will
6627 * not be load balanced. If the same cpumask appears both in the
6628 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6631 * The passed in 'doms_new' should be allocated using
6632 * alloc_sched_domains. This routine takes ownership of it and will
6633 * free_sched_domains it when done with it. If the caller failed the
6634 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6635 * and partition_sched_domains() will fallback to the single partition
6636 * 'fallback_doms', it also forces the domains to be rebuilt.
6638 * If doms_new == NULL it will be replaced with cpu_online_mask.
6639 * ndoms_new == 0 is a special case for destroying existing domains,
6640 * and it will not create the default domain.
6642 * Call with hotplug lock held
6644 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
6645 struct sched_domain_attr
*dattr_new
)
6650 mutex_lock(&sched_domains_mutex
);
6652 /* always unregister in case we don't destroy any domains */
6653 unregister_sched_domain_sysctl();
6655 /* Let architecture update cpu core mappings. */
6656 new_topology
= arch_update_cpu_topology();
6658 n
= doms_new
? ndoms_new
: 0;
6660 /* Destroy deleted domains */
6661 for (i
= 0; i
< ndoms_cur
; i
++) {
6662 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6663 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
6664 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
6667 /* no match - a current sched domain not in new doms_new[] */
6668 detach_destroy_domains(doms_cur
[i
]);
6673 if (doms_new
== NULL
) {
6675 doms_new
= &fallback_doms
;
6676 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
6677 WARN_ON_ONCE(dattr_new
);
6680 /* Build new domains */
6681 for (i
= 0; i
< ndoms_new
; i
++) {
6682 for (j
= 0; j
< ndoms_cur
&& !new_topology
; j
++) {
6683 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
6684 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
6687 /* no match - add a new doms_new */
6688 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
6693 /* Remember the new sched domains */
6694 if (doms_cur
!= &fallback_doms
)
6695 free_sched_domains(doms_cur
, ndoms_cur
);
6696 kfree(dattr_cur
); /* kfree(NULL) is safe */
6697 doms_cur
= doms_new
;
6698 dattr_cur
= dattr_new
;
6699 ndoms_cur
= ndoms_new
;
6701 register_sched_domain_sysctl();
6703 mutex_unlock(&sched_domains_mutex
);
6706 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
6709 * Update cpusets according to cpu_active mask. If cpusets are
6710 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6711 * around partition_sched_domains().
6713 * If we come here as part of a suspend/resume, don't touch cpusets because we
6714 * want to restore it back to its original state upon resume anyway.
6716 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
6720 case CPU_ONLINE_FROZEN
:
6721 case CPU_DOWN_FAILED_FROZEN
:
6724 * num_cpus_frozen tracks how many CPUs are involved in suspend
6725 * resume sequence. As long as this is not the last online
6726 * operation in the resume sequence, just build a single sched
6727 * domain, ignoring cpusets.
6730 if (likely(num_cpus_frozen
)) {
6731 partition_sched_domains(1, NULL
, NULL
);
6736 * This is the last CPU online operation. So fall through and
6737 * restore the original sched domains by considering the
6738 * cpuset configurations.
6742 case CPU_DOWN_FAILED
:
6743 cpuset_update_active_cpus(true);
6751 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
6755 case CPU_DOWN_PREPARE
:
6756 cpuset_update_active_cpus(false);
6758 case CPU_DOWN_PREPARE_FROZEN
:
6760 partition_sched_domains(1, NULL
, NULL
);
6768 void __init
sched_init_smp(void)
6770 cpumask_var_t non_isolated_cpus
;
6772 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
6773 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
6778 mutex_lock(&sched_domains_mutex
);
6779 init_sched_domains(cpu_active_mask
);
6780 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
6781 if (cpumask_empty(non_isolated_cpus
))
6782 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
6783 mutex_unlock(&sched_domains_mutex
);
6786 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
6787 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
6788 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
6790 /* RT runtime code needs to handle some hotplug events */
6791 hotcpu_notifier(update_runtime
, 0);
6795 /* Move init over to a non-isolated CPU */
6796 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
6798 sched_init_granularity();
6799 free_cpumask_var(non_isolated_cpus
);
6801 init_sched_rt_class();
6804 void __init
sched_init_smp(void)
6806 sched_init_granularity();
6808 #endif /* CONFIG_SMP */
6810 const_debug
unsigned int sysctl_timer_migration
= 1;
6812 int in_sched_functions(unsigned long addr
)
6814 return in_lock_functions(addr
) ||
6815 (addr
>= (unsigned long)__sched_text_start
6816 && addr
< (unsigned long)__sched_text_end
);
6819 #ifdef CONFIG_CGROUP_SCHED
6821 * Default task group.
6822 * Every task in system belongs to this group at bootup.
6824 struct task_group root_task_group
;
6825 LIST_HEAD(task_groups
);
6828 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
6830 void __init
sched_init(void)
6833 unsigned long alloc_size
= 0, ptr
;
6835 #ifdef CONFIG_FAIR_GROUP_SCHED
6836 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6838 #ifdef CONFIG_RT_GROUP_SCHED
6839 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6841 #ifdef CONFIG_CPUMASK_OFFSTACK
6842 alloc_size
+= num_possible_cpus() * cpumask_size();
6845 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
6847 #ifdef CONFIG_FAIR_GROUP_SCHED
6848 root_task_group
.se
= (struct sched_entity
**)ptr
;
6849 ptr
+= nr_cpu_ids
* sizeof(void **);
6851 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
6852 ptr
+= nr_cpu_ids
* sizeof(void **);
6854 #endif /* CONFIG_FAIR_GROUP_SCHED */
6855 #ifdef CONFIG_RT_GROUP_SCHED
6856 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
6857 ptr
+= nr_cpu_ids
* sizeof(void **);
6859 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
6860 ptr
+= nr_cpu_ids
* sizeof(void **);
6862 #endif /* CONFIG_RT_GROUP_SCHED */
6863 #ifdef CONFIG_CPUMASK_OFFSTACK
6864 for_each_possible_cpu(i
) {
6865 per_cpu(load_balance_mask
, i
) = (void *)ptr
;
6866 ptr
+= cpumask_size();
6868 #endif /* CONFIG_CPUMASK_OFFSTACK */
6872 init_defrootdomain();
6875 init_rt_bandwidth(&def_rt_bandwidth
,
6876 global_rt_period(), global_rt_runtime());
6878 #ifdef CONFIG_RT_GROUP_SCHED
6879 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
6880 global_rt_period(), global_rt_runtime());
6881 #endif /* CONFIG_RT_GROUP_SCHED */
6883 #ifdef CONFIG_CGROUP_SCHED
6884 list_add(&root_task_group
.list
, &task_groups
);
6885 INIT_LIST_HEAD(&root_task_group
.children
);
6886 INIT_LIST_HEAD(&root_task_group
.siblings
);
6887 autogroup_init(&init_task
);
6889 #endif /* CONFIG_CGROUP_SCHED */
6891 for_each_possible_cpu(i
) {
6895 raw_spin_lock_init(&rq
->lock
);
6897 rq
->calc_load_active
= 0;
6898 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
6899 init_cfs_rq(&rq
->cfs
);
6900 init_rt_rq(&rq
->rt
, rq
);
6901 #ifdef CONFIG_FAIR_GROUP_SCHED
6902 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
6903 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6905 * How much cpu bandwidth does root_task_group get?
6907 * In case of task-groups formed thr' the cgroup filesystem, it
6908 * gets 100% of the cpu resources in the system. This overall
6909 * system cpu resource is divided among the tasks of
6910 * root_task_group and its child task-groups in a fair manner,
6911 * based on each entity's (task or task-group's) weight
6912 * (se->load.weight).
6914 * In other words, if root_task_group has 10 tasks of weight
6915 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6916 * then A0's share of the cpu resource is:
6918 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6920 * We achieve this by letting root_task_group's tasks sit
6921 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6923 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
6924 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
6925 #endif /* CONFIG_FAIR_GROUP_SCHED */
6927 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
6928 #ifdef CONFIG_RT_GROUP_SCHED
6929 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
6930 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
6933 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6934 rq
->cpu_load
[j
] = 0;
6936 rq
->last_load_update_tick
= jiffies
;
6941 rq
->cpu_power
= SCHED_POWER_SCALE
;
6942 rq
->post_schedule
= 0;
6943 rq
->active_balance
= 0;
6944 rq
->next_balance
= jiffies
;
6949 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
6951 INIT_LIST_HEAD(&rq
->cfs_tasks
);
6953 rq_attach_root(rq
, &def_root_domain
);
6959 atomic_set(&rq
->nr_iowait
, 0);
6962 set_load_weight(&init_task
);
6964 #ifdef CONFIG_PREEMPT_NOTIFIERS
6965 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6968 #ifdef CONFIG_RT_MUTEXES
6969 plist_head_init(&init_task
.pi_waiters
);
6973 * The boot idle thread does lazy MMU switching as well:
6975 atomic_inc(&init_mm
.mm_count
);
6976 enter_lazy_tlb(&init_mm
, current
);
6979 * Make us the idle thread. Technically, schedule() should not be
6980 * called from this thread, however somewhere below it might be,
6981 * but because we are the idle thread, we just pick up running again
6982 * when this runqueue becomes "idle".
6984 init_idle(current
, smp_processor_id());
6986 calc_load_update
= jiffies
+ LOAD_FREQ
;
6989 * During early bootup we pretend to be a normal task:
6991 current
->sched_class
= &fair_sched_class
;
6994 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
6995 /* May be allocated at isolcpus cmdline parse time */
6996 if (cpu_isolated_map
== NULL
)
6997 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
6998 idle_thread_set_boot_cpu();
7000 init_sched_fair_class();
7002 scheduler_running
= 1;
7005 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7006 static inline int preempt_count_equals(int preempt_offset
)
7008 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
7010 return (nested
== preempt_offset
);
7013 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7015 static unsigned long prev_jiffy
; /* ratelimiting */
7017 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7018 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled()) ||
7019 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7021 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7023 prev_jiffy
= jiffies
;
7026 "BUG: sleeping function called from invalid context at %s:%d\n",
7029 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7030 in_atomic(), irqs_disabled(),
7031 current
->pid
, current
->comm
);
7033 debug_show_held_locks(current
);
7034 if (irqs_disabled())
7035 print_irqtrace_events(current
);
7038 EXPORT_SYMBOL(__might_sleep
);
7041 #ifdef CONFIG_MAGIC_SYSRQ
7042 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7044 const struct sched_class
*prev_class
= p
->sched_class
;
7045 int old_prio
= p
->prio
;
7050 dequeue_task(rq
, p
, 0);
7051 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
7053 enqueue_task(rq
, p
, 0);
7054 resched_task(rq
->curr
);
7057 check_class_changed(rq
, p
, prev_class
, old_prio
);
7060 void normalize_rt_tasks(void)
7062 struct task_struct
*g
, *p
;
7063 unsigned long flags
;
7066 read_lock_irqsave(&tasklist_lock
, flags
);
7067 do_each_thread(g
, p
) {
7069 * Only normalize user tasks:
7074 p
->se
.exec_start
= 0;
7075 #ifdef CONFIG_SCHEDSTATS
7076 p
->se
.statistics
.wait_start
= 0;
7077 p
->se
.statistics
.sleep_start
= 0;
7078 p
->se
.statistics
.block_start
= 0;
7083 * Renice negative nice level userspace
7086 if (TASK_NICE(p
) < 0 && p
->mm
)
7087 set_user_nice(p
, 0);
7091 raw_spin_lock(&p
->pi_lock
);
7092 rq
= __task_rq_lock(p
);
7094 normalize_task(rq
, p
);
7096 __task_rq_unlock(rq
);
7097 raw_spin_unlock(&p
->pi_lock
);
7098 } while_each_thread(g
, p
);
7100 read_unlock_irqrestore(&tasklist_lock
, flags
);
7103 #endif /* CONFIG_MAGIC_SYSRQ */
7105 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7107 * These functions are only useful for the IA64 MCA handling, or kdb.
7109 * They can only be called when the whole system has been
7110 * stopped - every CPU needs to be quiescent, and no scheduling
7111 * activity can take place. Using them for anything else would
7112 * be a serious bug, and as a result, they aren't even visible
7113 * under any other configuration.
7117 * curr_task - return the current task for a given cpu.
7118 * @cpu: the processor in question.
7120 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7122 struct task_struct
*curr_task(int cpu
)
7124 return cpu_curr(cpu
);
7127 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7131 * set_curr_task - set the current task for a given cpu.
7132 * @cpu: the processor in question.
7133 * @p: the task pointer to set.
7135 * Description: This function must only be used when non-maskable interrupts
7136 * are serviced on a separate stack. It allows the architecture to switch the
7137 * notion of the current task on a cpu in a non-blocking manner. This function
7138 * must be called with all CPU's synchronized, and interrupts disabled, the
7139 * and caller must save the original value of the current task (see
7140 * curr_task() above) and restore that value before reenabling interrupts and
7141 * re-starting the system.
7143 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7145 void set_curr_task(int cpu
, struct task_struct
*p
)
7152 #ifdef CONFIG_CGROUP_SCHED
7153 /* task_group_lock serializes the addition/removal of task groups */
7154 static DEFINE_SPINLOCK(task_group_lock
);
7156 static void free_sched_group(struct task_group
*tg
)
7158 free_fair_sched_group(tg
);
7159 free_rt_sched_group(tg
);
7164 /* allocate runqueue etc for a new task group */
7165 struct task_group
*sched_create_group(struct task_group
*parent
)
7167 struct task_group
*tg
;
7169 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7171 return ERR_PTR(-ENOMEM
);
7173 if (!alloc_fair_sched_group(tg
, parent
))
7176 if (!alloc_rt_sched_group(tg
, parent
))
7182 free_sched_group(tg
);
7183 return ERR_PTR(-ENOMEM
);
7186 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7188 unsigned long flags
;
7190 spin_lock_irqsave(&task_group_lock
, flags
);
7191 list_add_rcu(&tg
->list
, &task_groups
);
7193 WARN_ON(!parent
); /* root should already exist */
7195 tg
->parent
= parent
;
7196 INIT_LIST_HEAD(&tg
->children
);
7197 list_add_rcu(&tg
->siblings
, &parent
->children
);
7198 spin_unlock_irqrestore(&task_group_lock
, flags
);
7201 /* rcu callback to free various structures associated with a task group */
7202 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7204 /* now it should be safe to free those cfs_rqs */
7205 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7208 /* Destroy runqueue etc associated with a task group */
7209 void sched_destroy_group(struct task_group
*tg
)
7211 /* wait for possible concurrent references to cfs_rqs complete */
7212 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7215 void sched_offline_group(struct task_group
*tg
)
7217 unsigned long flags
;
7220 /* end participation in shares distribution */
7221 for_each_possible_cpu(i
)
7222 unregister_fair_sched_group(tg
, i
);
7224 spin_lock_irqsave(&task_group_lock
, flags
);
7225 list_del_rcu(&tg
->list
);
7226 list_del_rcu(&tg
->siblings
);
7227 spin_unlock_irqrestore(&task_group_lock
, flags
);
7230 /* change task's runqueue when it moves between groups.
7231 * The caller of this function should have put the task in its new group
7232 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7233 * reflect its new group.
7235 void sched_move_task(struct task_struct
*tsk
)
7237 struct task_group
*tg
;
7239 unsigned long flags
;
7242 rq
= task_rq_lock(tsk
, &flags
);
7244 running
= task_current(rq
, tsk
);
7248 dequeue_task(rq
, tsk
, 0);
7249 if (unlikely(running
))
7250 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7252 tg
= container_of(task_subsys_state_check(tsk
, cpu_cgroup_subsys_id
,
7253 lockdep_is_held(&tsk
->sighand
->siglock
)),
7254 struct task_group
, css
);
7255 tg
= autogroup_task_group(tsk
, tg
);
7256 tsk
->sched_task_group
= tg
;
7258 #ifdef CONFIG_FAIR_GROUP_SCHED
7259 if (tsk
->sched_class
->task_move_group
)
7260 tsk
->sched_class
->task_move_group(tsk
, on_rq
);
7263 set_task_rq(tsk
, task_cpu(tsk
));
7265 if (unlikely(running
))
7266 tsk
->sched_class
->set_curr_task(rq
);
7268 enqueue_task(rq
, tsk
, 0);
7270 task_rq_unlock(rq
, tsk
, &flags
);
7272 #endif /* CONFIG_CGROUP_SCHED */
7274 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
7275 static unsigned long to_ratio(u64 period
, u64 runtime
)
7277 if (runtime
== RUNTIME_INF
)
7280 return div64_u64(runtime
<< 20, period
);
7284 #ifdef CONFIG_RT_GROUP_SCHED
7286 * Ensure that the real time constraints are schedulable.
7288 static DEFINE_MUTEX(rt_constraints_mutex
);
7290 /* Must be called with tasklist_lock held */
7291 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7293 struct task_struct
*g
, *p
;
7295 do_each_thread(g
, p
) {
7296 if (rt_task(p
) && task_rq(p
)->rt
.tg
== tg
)
7298 } while_each_thread(g
, p
);
7303 struct rt_schedulable_data
{
7304 struct task_group
*tg
;
7309 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7311 struct rt_schedulable_data
*d
= data
;
7312 struct task_group
*child
;
7313 unsigned long total
, sum
= 0;
7314 u64 period
, runtime
;
7316 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7317 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7320 period
= d
->rt_period
;
7321 runtime
= d
->rt_runtime
;
7325 * Cannot have more runtime than the period.
7327 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7331 * Ensure we don't starve existing RT tasks.
7333 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7336 total
= to_ratio(period
, runtime
);
7339 * Nobody can have more than the global setting allows.
7341 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7345 * The sum of our children's runtime should not exceed our own.
7347 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7348 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7349 runtime
= child
->rt_bandwidth
.rt_runtime
;
7351 if (child
== d
->tg
) {
7352 period
= d
->rt_period
;
7353 runtime
= d
->rt_runtime
;
7356 sum
+= to_ratio(period
, runtime
);
7365 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7369 struct rt_schedulable_data data
= {
7371 .rt_period
= period
,
7372 .rt_runtime
= runtime
,
7376 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
7382 static int tg_set_rt_bandwidth(struct task_group
*tg
,
7383 u64 rt_period
, u64 rt_runtime
)
7387 mutex_lock(&rt_constraints_mutex
);
7388 read_lock(&tasklist_lock
);
7389 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
7393 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7394 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
7395 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
7397 for_each_possible_cpu(i
) {
7398 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
7400 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7401 rt_rq
->rt_runtime
= rt_runtime
;
7402 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7404 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7406 read_unlock(&tasklist_lock
);
7407 mutex_unlock(&rt_constraints_mutex
);
7412 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7414 u64 rt_runtime
, rt_period
;
7416 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7417 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7418 if (rt_runtime_us
< 0)
7419 rt_runtime
= RUNTIME_INF
;
7421 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7424 static long sched_group_rt_runtime(struct task_group
*tg
)
7428 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
7431 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
7432 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7433 return rt_runtime_us
;
7436 static int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
7438 u64 rt_runtime
, rt_period
;
7440 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
7441 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
7446 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7449 static long sched_group_rt_period(struct task_group
*tg
)
7453 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7454 do_div(rt_period_us
, NSEC_PER_USEC
);
7455 return rt_period_us
;
7458 static int sched_rt_global_constraints(void)
7460 u64 runtime
, period
;
7463 if (sysctl_sched_rt_period
<= 0)
7466 runtime
= global_rt_runtime();
7467 period
= global_rt_period();
7470 * Sanity check on the sysctl variables.
7472 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7475 mutex_lock(&rt_constraints_mutex
);
7476 read_lock(&tasklist_lock
);
7477 ret
= __rt_schedulable(NULL
, 0, 0);
7478 read_unlock(&tasklist_lock
);
7479 mutex_unlock(&rt_constraints_mutex
);
7484 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
7486 /* Don't accept realtime tasks when there is no way for them to run */
7487 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
7493 #else /* !CONFIG_RT_GROUP_SCHED */
7494 static int sched_rt_global_constraints(void)
7496 unsigned long flags
;
7499 if (sysctl_sched_rt_period
<= 0)
7503 * There's always some RT tasks in the root group
7504 * -- migration, kstopmachine etc..
7506 if (sysctl_sched_rt_runtime
== 0)
7509 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7510 for_each_possible_cpu(i
) {
7511 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
7513 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7514 rt_rq
->rt_runtime
= global_rt_runtime();
7515 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7517 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7521 #endif /* CONFIG_RT_GROUP_SCHED */
7523 int sched_rr_handler(struct ctl_table
*table
, int write
,
7524 void __user
*buffer
, size_t *lenp
,
7528 static DEFINE_MUTEX(mutex
);
7531 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7532 /* make sure that internally we keep jiffies */
7533 /* also, writing zero resets timeslice to default */
7534 if (!ret
&& write
) {
7535 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
7536 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
7538 mutex_unlock(&mutex
);
7542 int sched_rt_handler(struct ctl_table
*table
, int write
,
7543 void __user
*buffer
, size_t *lenp
,
7547 int old_period
, old_runtime
;
7548 static DEFINE_MUTEX(mutex
);
7551 old_period
= sysctl_sched_rt_period
;
7552 old_runtime
= sysctl_sched_rt_runtime
;
7554 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7556 if (!ret
&& write
) {
7557 ret
= sched_rt_global_constraints();
7559 sysctl_sched_rt_period
= old_period
;
7560 sysctl_sched_rt_runtime
= old_runtime
;
7562 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
7563 def_rt_bandwidth
.rt_period
=
7564 ns_to_ktime(global_rt_period());
7567 mutex_unlock(&mutex
);
7572 #ifdef CONFIG_CGROUP_SCHED
7574 /* return corresponding task_group object of a cgroup */
7575 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7577 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7578 struct task_group
, css
);
7581 static struct cgroup_subsys_state
*cpu_cgroup_css_alloc(struct cgroup
*cgrp
)
7583 struct task_group
*tg
, *parent
;
7585 if (!cgrp
->parent
) {
7586 /* This is early initialization for the top cgroup */
7587 return &root_task_group
.css
;
7590 parent
= cgroup_tg(cgrp
->parent
);
7591 tg
= sched_create_group(parent
);
7593 return ERR_PTR(-ENOMEM
);
7598 static int cpu_cgroup_css_online(struct cgroup
*cgrp
)
7600 struct task_group
*tg
= cgroup_tg(cgrp
);
7601 struct task_group
*parent
;
7606 parent
= cgroup_tg(cgrp
->parent
);
7607 sched_online_group(tg
, parent
);
7611 static void cpu_cgroup_css_free(struct cgroup
*cgrp
)
7613 struct task_group
*tg
= cgroup_tg(cgrp
);
7615 sched_destroy_group(tg
);
7618 static void cpu_cgroup_css_offline(struct cgroup
*cgrp
)
7620 struct task_group
*tg
= cgroup_tg(cgrp
);
7622 sched_offline_group(tg
);
7625 static int cpu_cgroup_can_attach(struct cgroup
*cgrp
,
7626 struct cgroup_taskset
*tset
)
7628 struct task_struct
*task
;
7630 cgroup_taskset_for_each(task
, cgrp
, tset
) {
7631 #ifdef CONFIG_RT_GROUP_SCHED
7632 if (!sched_rt_can_attach(cgroup_tg(cgrp
), task
))
7635 /* We don't support RT-tasks being in separate groups */
7636 if (task
->sched_class
!= &fair_sched_class
)
7643 static void cpu_cgroup_attach(struct cgroup
*cgrp
,
7644 struct cgroup_taskset
*tset
)
7646 struct task_struct
*task
;
7648 cgroup_taskset_for_each(task
, cgrp
, tset
)
7649 sched_move_task(task
);
7653 cpu_cgroup_exit(struct cgroup
*cgrp
, struct cgroup
*old_cgrp
,
7654 struct task_struct
*task
)
7657 * cgroup_exit() is called in the copy_process() failure path.
7658 * Ignore this case since the task hasn't ran yet, this avoids
7659 * trying to poke a half freed task state from generic code.
7661 if (!(task
->flags
& PF_EXITING
))
7664 sched_move_task(task
);
7667 #ifdef CONFIG_FAIR_GROUP_SCHED
7668 static int cpu_shares_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7671 return sched_group_set_shares(cgroup_tg(cgrp
), scale_load(shareval
));
7674 static u64
cpu_shares_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7676 struct task_group
*tg
= cgroup_tg(cgrp
);
7678 return (u64
) scale_load_down(tg
->shares
);
7681 #ifdef CONFIG_CFS_BANDWIDTH
7682 static DEFINE_MUTEX(cfs_constraints_mutex
);
7684 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
7685 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
7687 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
7689 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
7691 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
7692 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7694 if (tg
== &root_task_group
)
7698 * Ensure we have at some amount of bandwidth every period. This is
7699 * to prevent reaching a state of large arrears when throttled via
7700 * entity_tick() resulting in prolonged exit starvation.
7702 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
7706 * Likewise, bound things on the otherside by preventing insane quota
7707 * periods. This also allows us to normalize in computing quota
7710 if (period
> max_cfs_quota_period
)
7713 mutex_lock(&cfs_constraints_mutex
);
7714 ret
= __cfs_schedulable(tg
, period
, quota
);
7718 runtime_enabled
= quota
!= RUNTIME_INF
;
7719 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
7720 account_cfs_bandwidth_used(runtime_enabled
, runtime_was_enabled
);
7721 raw_spin_lock_irq(&cfs_b
->lock
);
7722 cfs_b
->period
= ns_to_ktime(period
);
7723 cfs_b
->quota
= quota
;
7725 __refill_cfs_bandwidth_runtime(cfs_b
);
7726 /* restart the period timer (if active) to handle new period expiry */
7727 if (runtime_enabled
&& cfs_b
->timer_active
) {
7728 /* force a reprogram */
7729 cfs_b
->timer_active
= 0;
7730 __start_cfs_bandwidth(cfs_b
);
7732 raw_spin_unlock_irq(&cfs_b
->lock
);
7734 for_each_possible_cpu(i
) {
7735 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
7736 struct rq
*rq
= cfs_rq
->rq
;
7738 raw_spin_lock_irq(&rq
->lock
);
7739 cfs_rq
->runtime_enabled
= runtime_enabled
;
7740 cfs_rq
->runtime_remaining
= 0;
7742 if (cfs_rq
->throttled
)
7743 unthrottle_cfs_rq(cfs_rq
);
7744 raw_spin_unlock_irq(&rq
->lock
);
7747 mutex_unlock(&cfs_constraints_mutex
);
7752 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
7756 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7757 if (cfs_quota_us
< 0)
7758 quota
= RUNTIME_INF
;
7760 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
7762 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7765 long tg_get_cfs_quota(struct task_group
*tg
)
7769 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
7772 quota_us
= tg
->cfs_bandwidth
.quota
;
7773 do_div(quota_us
, NSEC_PER_USEC
);
7778 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
7782 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
7783 quota
= tg
->cfs_bandwidth
.quota
;
7785 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7788 long tg_get_cfs_period(struct task_group
*tg
)
7792 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7793 do_div(cfs_period_us
, NSEC_PER_USEC
);
7795 return cfs_period_us
;
7798 static s64
cpu_cfs_quota_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
)
7800 return tg_get_cfs_quota(cgroup_tg(cgrp
));
7803 static int cpu_cfs_quota_write_s64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7806 return tg_set_cfs_quota(cgroup_tg(cgrp
), cfs_quota_us
);
7809 static u64
cpu_cfs_period_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7811 return tg_get_cfs_period(cgroup_tg(cgrp
));
7814 static int cpu_cfs_period_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7817 return tg_set_cfs_period(cgroup_tg(cgrp
), cfs_period_us
);
7820 struct cfs_schedulable_data
{
7821 struct task_group
*tg
;
7826 * normalize group quota/period to be quota/max_period
7827 * note: units are usecs
7829 static u64
normalize_cfs_quota(struct task_group
*tg
,
7830 struct cfs_schedulable_data
*d
)
7838 period
= tg_get_cfs_period(tg
);
7839 quota
= tg_get_cfs_quota(tg
);
7842 /* note: these should typically be equivalent */
7843 if (quota
== RUNTIME_INF
|| quota
== -1)
7846 return to_ratio(period
, quota
);
7849 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
7851 struct cfs_schedulable_data
*d
= data
;
7852 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7853 s64 quota
= 0, parent_quota
= -1;
7856 quota
= RUNTIME_INF
;
7858 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
7860 quota
= normalize_cfs_quota(tg
, d
);
7861 parent_quota
= parent_b
->hierarchal_quota
;
7864 * ensure max(child_quota) <= parent_quota, inherit when no
7867 if (quota
== RUNTIME_INF
)
7868 quota
= parent_quota
;
7869 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
7872 cfs_b
->hierarchal_quota
= quota
;
7877 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
7880 struct cfs_schedulable_data data
= {
7886 if (quota
!= RUNTIME_INF
) {
7887 do_div(data
.period
, NSEC_PER_USEC
);
7888 do_div(data
.quota
, NSEC_PER_USEC
);
7892 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
7898 static int cpu_stats_show(struct cgroup
*cgrp
, struct cftype
*cft
,
7899 struct cgroup_map_cb
*cb
)
7901 struct task_group
*tg
= cgroup_tg(cgrp
);
7902 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7904 cb
->fill(cb
, "nr_periods", cfs_b
->nr_periods
);
7905 cb
->fill(cb
, "nr_throttled", cfs_b
->nr_throttled
);
7906 cb
->fill(cb
, "throttled_time", cfs_b
->throttled_time
);
7910 #endif /* CONFIG_CFS_BANDWIDTH */
7911 #endif /* CONFIG_FAIR_GROUP_SCHED */
7913 #ifdef CONFIG_RT_GROUP_SCHED
7914 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
7917 return sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
7920 static s64
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
)
7922 return sched_group_rt_runtime(cgroup_tg(cgrp
));
7925 static int cpu_rt_period_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
7928 return sched_group_set_rt_period(cgroup_tg(cgrp
), rt_period_us
);
7931 static u64
cpu_rt_period_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
7933 return sched_group_rt_period(cgroup_tg(cgrp
));
7935 #endif /* CONFIG_RT_GROUP_SCHED */
7937 static struct cftype cpu_files
[] = {
7938 #ifdef CONFIG_FAIR_GROUP_SCHED
7941 .read_u64
= cpu_shares_read_u64
,
7942 .write_u64
= cpu_shares_write_u64
,
7945 #ifdef CONFIG_CFS_BANDWIDTH
7947 .name
= "cfs_quota_us",
7948 .read_s64
= cpu_cfs_quota_read_s64
,
7949 .write_s64
= cpu_cfs_quota_write_s64
,
7952 .name
= "cfs_period_us",
7953 .read_u64
= cpu_cfs_period_read_u64
,
7954 .write_u64
= cpu_cfs_period_write_u64
,
7958 .read_map
= cpu_stats_show
,
7961 #ifdef CONFIG_RT_GROUP_SCHED
7963 .name
= "rt_runtime_us",
7964 .read_s64
= cpu_rt_runtime_read
,
7965 .write_s64
= cpu_rt_runtime_write
,
7968 .name
= "rt_period_us",
7969 .read_u64
= cpu_rt_period_read_uint
,
7970 .write_u64
= cpu_rt_period_write_uint
,
7976 struct cgroup_subsys cpu_cgroup_subsys
= {
7978 .css_alloc
= cpu_cgroup_css_alloc
,
7979 .css_free
= cpu_cgroup_css_free
,
7980 .css_online
= cpu_cgroup_css_online
,
7981 .css_offline
= cpu_cgroup_css_offline
,
7982 .can_attach
= cpu_cgroup_can_attach
,
7983 .attach
= cpu_cgroup_attach
,
7984 .exit
= cpu_cgroup_exit
,
7985 .subsys_id
= cpu_cgroup_subsys_id
,
7986 .base_cftypes
= cpu_files
,
7990 #endif /* CONFIG_CGROUP_SCHED */
7992 void dump_cpu_task(int cpu
)
7994 pr_info("Task dump for CPU %d:\n", cpu
);
7995 sched_show_task(cpu_curr(cpu
));