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
516 #ifndef tsk_is_polling
517 #define tsk_is_polling(t) 0
520 void resched_task(struct task_struct
*p
)
524 assert_raw_spin_locked(&task_rq(p
)->lock
);
526 if (test_tsk_need_resched(p
))
529 set_tsk_need_resched(p
);
532 if (cpu
== smp_processor_id())
535 /* NEED_RESCHED must be visible before we test polling */
537 if (!tsk_is_polling(p
))
538 smp_send_reschedule(cpu
);
541 void resched_cpu(int cpu
)
543 struct rq
*rq
= cpu_rq(cpu
);
546 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
548 resched_task(cpu_curr(cpu
));
549 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
554 * In the semi idle case, use the nearest busy cpu for migrating timers
555 * from an idle cpu. This is good for power-savings.
557 * We don't do similar optimization for completely idle system, as
558 * selecting an idle cpu will add more delays to the timers than intended
559 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
561 int get_nohz_timer_target(void)
563 int cpu
= smp_processor_id();
565 struct sched_domain
*sd
;
568 for_each_domain(cpu
, sd
) {
569 for_each_cpu(i
, sched_domain_span(sd
)) {
581 * When add_timer_on() enqueues a timer into the timer wheel of an
582 * idle CPU then this timer might expire before the next timer event
583 * which is scheduled to wake up that CPU. In case of a completely
584 * idle system the next event might even be infinite time into the
585 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
586 * leaves the inner idle loop so the newly added timer is taken into
587 * account when the CPU goes back to idle and evaluates the timer
588 * wheel for the next timer event.
590 void wake_up_idle_cpu(int cpu
)
592 struct rq
*rq
= cpu_rq(cpu
);
594 if (cpu
== smp_processor_id())
598 * This is safe, as this function is called with the timer
599 * wheel base lock of (cpu) held. When the CPU is on the way
600 * to idle and has not yet set rq->curr to idle then it will
601 * be serialized on the timer wheel base lock and take the new
602 * timer into account automatically.
604 if (rq
->curr
!= rq
->idle
)
608 * We can set TIF_RESCHED on the idle task of the other CPU
609 * lockless. The worst case is that the other CPU runs the
610 * idle task through an additional NOOP schedule()
612 set_tsk_need_resched(rq
->idle
);
614 /* NEED_RESCHED must be visible before we test polling */
616 if (!tsk_is_polling(rq
->idle
))
617 smp_send_reschedule(cpu
);
620 static inline bool got_nohz_idle_kick(void)
622 int cpu
= smp_processor_id();
623 return idle_cpu(cpu
) && test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
626 #else /* CONFIG_NO_HZ */
628 static inline bool got_nohz_idle_kick(void)
633 #endif /* CONFIG_NO_HZ */
635 void sched_avg_update(struct rq
*rq
)
637 s64 period
= sched_avg_period();
639 while ((s64
)(rq
->clock
- rq
->age_stamp
) > period
) {
641 * Inline assembly required to prevent the compiler
642 * optimising this loop into a divmod call.
643 * See __iter_div_u64_rem() for another example of this.
645 asm("" : "+rm" (rq
->age_stamp
));
646 rq
->age_stamp
+= period
;
651 #else /* !CONFIG_SMP */
652 void resched_task(struct task_struct
*p
)
654 assert_raw_spin_locked(&task_rq(p
)->lock
);
655 set_tsk_need_resched(p
);
657 #endif /* CONFIG_SMP */
659 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
660 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
662 * Iterate task_group tree rooted at *from, calling @down when first entering a
663 * node and @up when leaving it for the final time.
665 * Caller must hold rcu_lock or sufficient equivalent.
667 int walk_tg_tree_from(struct task_group
*from
,
668 tg_visitor down
, tg_visitor up
, void *data
)
670 struct task_group
*parent
, *child
;
676 ret
= (*down
)(parent
, data
);
679 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
686 ret
= (*up
)(parent
, data
);
687 if (ret
|| parent
== from
)
691 parent
= parent
->parent
;
698 int tg_nop(struct task_group
*tg
, void *data
)
704 static void set_load_weight(struct task_struct
*p
)
706 int prio
= p
->static_prio
- MAX_RT_PRIO
;
707 struct load_weight
*load
= &p
->se
.load
;
710 * SCHED_IDLE tasks get minimal weight:
712 if (p
->policy
== SCHED_IDLE
) {
713 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
714 load
->inv_weight
= WMULT_IDLEPRIO
;
718 load
->weight
= scale_load(prio_to_weight
[prio
]);
719 load
->inv_weight
= prio_to_wmult
[prio
];
722 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
725 sched_info_queued(p
);
726 p
->sched_class
->enqueue_task(rq
, p
, flags
);
729 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
732 sched_info_dequeued(p
);
733 p
->sched_class
->dequeue_task(rq
, p
, flags
);
736 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
738 if (task_contributes_to_load(p
))
739 rq
->nr_uninterruptible
--;
741 enqueue_task(rq
, p
, flags
);
744 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
746 if (task_contributes_to_load(p
))
747 rq
->nr_uninterruptible
++;
749 dequeue_task(rq
, p
, flags
);
752 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
755 * In theory, the compile should just see 0 here, and optimize out the call
756 * to sched_rt_avg_update. But I don't trust it...
758 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
759 s64 steal
= 0, irq_delta
= 0;
761 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
762 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
765 * Since irq_time is only updated on {soft,}irq_exit, we might run into
766 * this case when a previous update_rq_clock() happened inside a
769 * When this happens, we stop ->clock_task and only update the
770 * prev_irq_time stamp to account for the part that fit, so that a next
771 * update will consume the rest. This ensures ->clock_task is
774 * It does however cause some slight miss-attribution of {soft,}irq
775 * time, a more accurate solution would be to update the irq_time using
776 * the current rq->clock timestamp, except that would require using
779 if (irq_delta
> delta
)
782 rq
->prev_irq_time
+= irq_delta
;
785 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
786 if (static_key_false((¶virt_steal_rq_enabled
))) {
789 steal
= paravirt_steal_clock(cpu_of(rq
));
790 steal
-= rq
->prev_steal_time_rq
;
792 if (unlikely(steal
> delta
))
795 st
= steal_ticks(steal
);
796 steal
= st
* TICK_NSEC
;
798 rq
->prev_steal_time_rq
+= steal
;
804 rq
->clock_task
+= delta
;
806 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
807 if ((irq_delta
+ steal
) && sched_feat(NONTASK_POWER
))
808 sched_rt_avg_update(rq
, irq_delta
+ steal
);
812 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
814 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
815 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
819 * Make it appear like a SCHED_FIFO task, its something
820 * userspace knows about and won't get confused about.
822 * Also, it will make PI more or less work without too
823 * much confusion -- but then, stop work should not
824 * rely on PI working anyway.
826 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
828 stop
->sched_class
= &stop_sched_class
;
831 cpu_rq(cpu
)->stop
= stop
;
835 * Reset it back to a normal scheduling class so that
836 * it can die in pieces.
838 old_stop
->sched_class
= &rt_sched_class
;
843 * __normal_prio - return the priority that is based on the static prio
845 static inline int __normal_prio(struct task_struct
*p
)
847 return p
->static_prio
;
851 * Calculate the expected normal priority: i.e. priority
852 * without taking RT-inheritance into account. Might be
853 * boosted by interactivity modifiers. Changes upon fork,
854 * setprio syscalls, and whenever the interactivity
855 * estimator recalculates.
857 static inline int normal_prio(struct task_struct
*p
)
861 if (task_has_rt_policy(p
))
862 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
864 prio
= __normal_prio(p
);
869 * Calculate the current priority, i.e. the priority
870 * taken into account by the scheduler. This value might
871 * be boosted by RT tasks, or might be boosted by
872 * interactivity modifiers. Will be RT if the task got
873 * RT-boosted. If not then it returns p->normal_prio.
875 static int effective_prio(struct task_struct
*p
)
877 p
->normal_prio
= normal_prio(p
);
879 * If we are RT tasks or we were boosted to RT priority,
880 * keep the priority unchanged. Otherwise, update priority
881 * to the normal priority:
883 if (!rt_prio(p
->prio
))
884 return p
->normal_prio
;
889 * task_curr - is this task currently executing on a CPU?
890 * @p: the task in question.
892 inline int task_curr(const struct task_struct
*p
)
894 return cpu_curr(task_cpu(p
)) == p
;
897 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
898 const struct sched_class
*prev_class
,
901 if (prev_class
!= p
->sched_class
) {
902 if (prev_class
->switched_from
)
903 prev_class
->switched_from(rq
, p
);
904 p
->sched_class
->switched_to(rq
, p
);
905 } else if (oldprio
!= p
->prio
)
906 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
909 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
911 const struct sched_class
*class;
913 if (p
->sched_class
== rq
->curr
->sched_class
) {
914 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
916 for_each_class(class) {
917 if (class == rq
->curr
->sched_class
)
919 if (class == p
->sched_class
) {
920 resched_task(rq
->curr
);
927 * A queue event has occurred, and we're going to schedule. In
928 * this case, we can save a useless back to back clock update.
930 if (rq
->curr
->on_rq
&& test_tsk_need_resched(rq
->curr
))
931 rq
->skip_clock_update
= 1;
934 static ATOMIC_NOTIFIER_HEAD(task_migration_notifier
);
936 void register_task_migration_notifier(struct notifier_block
*n
)
938 atomic_notifier_chain_register(&task_migration_notifier
, n
);
942 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
944 #ifdef CONFIG_SCHED_DEBUG
946 * We should never call set_task_cpu() on a blocked task,
947 * ttwu() will sort out the placement.
949 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
950 !(task_thread_info(p
)->preempt_count
& PREEMPT_ACTIVE
));
952 #ifdef CONFIG_LOCKDEP
954 * The caller should hold either p->pi_lock or rq->lock, when changing
955 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
957 * sched_move_task() holds both and thus holding either pins the cgroup,
960 * Furthermore, all task_rq users should acquire both locks, see
963 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
964 lockdep_is_held(&task_rq(p
)->lock
)));
968 trace_sched_migrate_task(p
, new_cpu
);
970 if (task_cpu(p
) != new_cpu
) {
971 struct task_migration_notifier tmn
;
973 if (p
->sched_class
->migrate_task_rq
)
974 p
->sched_class
->migrate_task_rq(p
, new_cpu
);
975 p
->se
.nr_migrations
++;
976 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, NULL
, 0);
979 tmn
.from_cpu
= task_cpu(p
);
980 tmn
.to_cpu
= new_cpu
;
982 atomic_notifier_call_chain(&task_migration_notifier
, 0, &tmn
);
985 __set_task_cpu(p
, new_cpu
);
988 struct migration_arg
{
989 struct task_struct
*task
;
993 static int migration_cpu_stop(void *data
);
996 * wait_task_inactive - wait for a thread to unschedule.
998 * If @match_state is nonzero, it's the @p->state value just checked and
999 * not expected to change. If it changes, i.e. @p might have woken up,
1000 * then return zero. When we succeed in waiting for @p to be off its CPU,
1001 * we return a positive number (its total switch count). If a second call
1002 * a short while later returns the same number, the caller can be sure that
1003 * @p has remained unscheduled the whole time.
1005 * The caller must ensure that the task *will* unschedule sometime soon,
1006 * else this function might spin for a *long* time. This function can't
1007 * be called with interrupts off, or it may introduce deadlock with
1008 * smp_call_function() if an IPI is sent by the same process we are
1009 * waiting to become inactive.
1011 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1013 unsigned long flags
;
1020 * We do the initial early heuristics without holding
1021 * any task-queue locks at all. We'll only try to get
1022 * the runqueue lock when things look like they will
1028 * If the task is actively running on another CPU
1029 * still, just relax and busy-wait without holding
1032 * NOTE! Since we don't hold any locks, it's not
1033 * even sure that "rq" stays as the right runqueue!
1034 * But we don't care, since "task_running()" will
1035 * return false if the runqueue has changed and p
1036 * is actually now running somewhere else!
1038 while (task_running(rq
, p
)) {
1039 if (match_state
&& unlikely(p
->state
!= match_state
))
1045 * Ok, time to look more closely! We need the rq
1046 * lock now, to be *sure*. If we're wrong, we'll
1047 * just go back and repeat.
1049 rq
= task_rq_lock(p
, &flags
);
1050 trace_sched_wait_task(p
);
1051 running
= task_running(rq
, p
);
1054 if (!match_state
|| p
->state
== match_state
)
1055 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1056 task_rq_unlock(rq
, p
, &flags
);
1059 * If it changed from the expected state, bail out now.
1061 if (unlikely(!ncsw
))
1065 * Was it really running after all now that we
1066 * checked with the proper locks actually held?
1068 * Oops. Go back and try again..
1070 if (unlikely(running
)) {
1076 * It's not enough that it's not actively running,
1077 * it must be off the runqueue _entirely_, and not
1080 * So if it was still runnable (but just not actively
1081 * running right now), it's preempted, and we should
1082 * yield - it could be a while.
1084 if (unlikely(on_rq
)) {
1085 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1087 set_current_state(TASK_UNINTERRUPTIBLE
);
1088 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1093 * Ahh, all good. It wasn't running, and it wasn't
1094 * runnable, which means that it will never become
1095 * running in the future either. We're all done!
1104 * kick_process - kick a running thread to enter/exit the kernel
1105 * @p: the to-be-kicked thread
1107 * Cause a process which is running on another CPU to enter
1108 * kernel-mode, without any delay. (to get signals handled.)
1110 * NOTE: this function doesn't have to take the runqueue lock,
1111 * because all it wants to ensure is that the remote task enters
1112 * the kernel. If the IPI races and the task has been migrated
1113 * to another CPU then no harm is done and the purpose has been
1116 void kick_process(struct task_struct
*p
)
1122 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1123 smp_send_reschedule(cpu
);
1126 EXPORT_SYMBOL_GPL(kick_process
);
1127 #endif /* CONFIG_SMP */
1131 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1133 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1135 int nid
= cpu_to_node(cpu
);
1136 const struct cpumask
*nodemask
= NULL
;
1137 enum { cpuset
, possible
, fail
} state
= cpuset
;
1141 * If the node that the cpu is on has been offlined, cpu_to_node()
1142 * will return -1. There is no cpu on the node, and we should
1143 * select the cpu on the other node.
1146 nodemask
= cpumask_of_node(nid
);
1148 /* Look for allowed, online CPU in same node. */
1149 for_each_cpu(dest_cpu
, nodemask
) {
1150 if (!cpu_online(dest_cpu
))
1152 if (!cpu_active(dest_cpu
))
1154 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1160 /* Any allowed, online CPU? */
1161 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1162 if (!cpu_online(dest_cpu
))
1164 if (!cpu_active(dest_cpu
))
1171 /* No more Mr. Nice Guy. */
1172 cpuset_cpus_allowed_fallback(p
);
1177 do_set_cpus_allowed(p
, cpu_possible_mask
);
1188 if (state
!= cpuset
) {
1190 * Don't tell them about moving exiting tasks or
1191 * kernel threads (both mm NULL), since they never
1194 if (p
->mm
&& printk_ratelimit()) {
1195 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1196 task_pid_nr(p
), p
->comm
, cpu
);
1204 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1207 int select_task_rq(struct task_struct
*p
, int sd_flags
, int wake_flags
)
1209 int cpu
= p
->sched_class
->select_task_rq(p
, sd_flags
, wake_flags
);
1212 * In order not to call set_task_cpu() on a blocking task we need
1213 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1216 * Since this is common to all placement strategies, this lives here.
1218 * [ this allows ->select_task() to simply return task_cpu(p) and
1219 * not worry about this generic constraint ]
1221 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1223 cpu
= select_fallback_rq(task_cpu(p
), p
);
1228 static void update_avg(u64
*avg
, u64 sample
)
1230 s64 diff
= sample
- *avg
;
1236 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1238 #ifdef CONFIG_SCHEDSTATS
1239 struct rq
*rq
= this_rq();
1242 int this_cpu
= smp_processor_id();
1244 if (cpu
== this_cpu
) {
1245 schedstat_inc(rq
, ttwu_local
);
1246 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1248 struct sched_domain
*sd
;
1250 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1252 for_each_domain(this_cpu
, sd
) {
1253 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1254 schedstat_inc(sd
, ttwu_wake_remote
);
1261 if (wake_flags
& WF_MIGRATED
)
1262 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1264 #endif /* CONFIG_SMP */
1266 schedstat_inc(rq
, ttwu_count
);
1267 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1269 if (wake_flags
& WF_SYNC
)
1270 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1272 #endif /* CONFIG_SCHEDSTATS */
1275 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1277 activate_task(rq
, p
, en_flags
);
1280 /* if a worker is waking up, notify workqueue */
1281 if (p
->flags
& PF_WQ_WORKER
)
1282 wq_worker_waking_up(p
, cpu_of(rq
));
1286 * Mark the task runnable and perform wakeup-preemption.
1289 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1291 trace_sched_wakeup(p
, true);
1292 check_preempt_curr(rq
, p
, wake_flags
);
1294 p
->state
= TASK_RUNNING
;
1296 if (p
->sched_class
->task_woken
)
1297 p
->sched_class
->task_woken(rq
, p
);
1299 if (rq
->idle_stamp
) {
1300 u64 delta
= rq
->clock
- rq
->idle_stamp
;
1301 u64 max
= 2*sysctl_sched_migration_cost
;
1306 update_avg(&rq
->avg_idle
, delta
);
1313 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1316 if (p
->sched_contributes_to_load
)
1317 rq
->nr_uninterruptible
--;
1320 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1321 ttwu_do_wakeup(rq
, p
, wake_flags
);
1325 * Called in case the task @p isn't fully descheduled from its runqueue,
1326 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1327 * since all we need to do is flip p->state to TASK_RUNNING, since
1328 * the task is still ->on_rq.
1330 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1335 rq
= __task_rq_lock(p
);
1337 ttwu_do_wakeup(rq
, p
, wake_flags
);
1340 __task_rq_unlock(rq
);
1346 static void sched_ttwu_pending(void)
1348 struct rq
*rq
= this_rq();
1349 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1350 struct task_struct
*p
;
1352 raw_spin_lock(&rq
->lock
);
1355 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1356 llist
= llist_next(llist
);
1357 ttwu_do_activate(rq
, p
, 0);
1360 raw_spin_unlock(&rq
->lock
);
1363 void scheduler_ipi(void)
1365 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick())
1369 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1370 * traditionally all their work was done from the interrupt return
1371 * path. Now that we actually do some work, we need to make sure
1374 * Some archs already do call them, luckily irq_enter/exit nest
1377 * Arguably we should visit all archs and update all handlers,
1378 * however a fair share of IPIs are still resched only so this would
1379 * somewhat pessimize the simple resched case.
1382 sched_ttwu_pending();
1385 * Check if someone kicked us for doing the nohz idle load balance.
1387 if (unlikely(got_nohz_idle_kick() && !need_resched())) {
1388 this_rq()->idle_balance
= 1;
1389 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1394 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1396 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
))
1397 smp_send_reschedule(cpu
);
1400 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1402 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1404 #endif /* CONFIG_SMP */
1406 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1408 struct rq
*rq
= cpu_rq(cpu
);
1410 #if defined(CONFIG_SMP)
1411 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1412 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1413 ttwu_queue_remote(p
, cpu
);
1418 raw_spin_lock(&rq
->lock
);
1419 ttwu_do_activate(rq
, p
, 0);
1420 raw_spin_unlock(&rq
->lock
);
1424 * try_to_wake_up - wake up a thread
1425 * @p: the thread to be awakened
1426 * @state: the mask of task states that can be woken
1427 * @wake_flags: wake modifier flags (WF_*)
1429 * Put it on the run-queue if it's not already there. The "current"
1430 * thread is always on the run-queue (except when the actual
1431 * re-schedule is in progress), and as such you're allowed to do
1432 * the simpler "current->state = TASK_RUNNING" to mark yourself
1433 * runnable without the overhead of this.
1435 * Returns %true if @p was woken up, %false if it was already running
1436 * or @state didn't match @p's state.
1439 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
1441 unsigned long flags
;
1442 int cpu
, success
= 0;
1445 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1446 if (!(p
->state
& state
))
1449 success
= 1; /* we're going to change ->state */
1452 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
1457 * If the owning (remote) cpu is still in the middle of schedule() with
1458 * this task as prev, wait until its done referencing the task.
1463 * Pairs with the smp_wmb() in finish_lock_switch().
1467 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
1468 p
->state
= TASK_WAKING
;
1470 if (p
->sched_class
->task_waking
)
1471 p
->sched_class
->task_waking(p
);
1473 cpu
= select_task_rq(p
, SD_BALANCE_WAKE
, wake_flags
);
1474 if (task_cpu(p
) != cpu
) {
1475 wake_flags
|= WF_MIGRATED
;
1476 set_task_cpu(p
, cpu
);
1478 #endif /* CONFIG_SMP */
1482 ttwu_stat(p
, cpu
, wake_flags
);
1484 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1490 * try_to_wake_up_local - try to wake up a local task with rq lock held
1491 * @p: the thread to be awakened
1493 * Put @p on the run-queue if it's not already there. The caller must
1494 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1497 static void try_to_wake_up_local(struct task_struct
*p
)
1499 struct rq
*rq
= task_rq(p
);
1501 BUG_ON(rq
!= this_rq());
1502 BUG_ON(p
== current
);
1503 lockdep_assert_held(&rq
->lock
);
1505 if (!raw_spin_trylock(&p
->pi_lock
)) {
1506 raw_spin_unlock(&rq
->lock
);
1507 raw_spin_lock(&p
->pi_lock
);
1508 raw_spin_lock(&rq
->lock
);
1511 if (!(p
->state
& TASK_NORMAL
))
1515 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
1517 ttwu_do_wakeup(rq
, p
, 0);
1518 ttwu_stat(p
, smp_processor_id(), 0);
1520 raw_spin_unlock(&p
->pi_lock
);
1524 * wake_up_process - Wake up a specific process
1525 * @p: The process to be woken up.
1527 * Attempt to wake up the nominated process and move it to the set of runnable
1528 * processes. Returns 1 if the process was woken up, 0 if it was already
1531 * It may be assumed that this function implies a write memory barrier before
1532 * changing the task state if and only if any tasks are woken up.
1534 int wake_up_process(struct task_struct
*p
)
1536 WARN_ON(task_is_stopped_or_traced(p
));
1537 return try_to_wake_up(p
, TASK_NORMAL
, 0);
1539 EXPORT_SYMBOL(wake_up_process
);
1541 int wake_up_state(struct task_struct
*p
, unsigned int state
)
1543 return try_to_wake_up(p
, state
, 0);
1547 * Perform scheduler related setup for a newly forked process p.
1548 * p is forked by current.
1550 * __sched_fork() is basic setup used by init_idle() too:
1552 static void __sched_fork(struct task_struct
*p
)
1557 p
->se
.exec_start
= 0;
1558 p
->se
.sum_exec_runtime
= 0;
1559 p
->se
.prev_sum_exec_runtime
= 0;
1560 p
->se
.nr_migrations
= 0;
1562 INIT_LIST_HEAD(&p
->se
.group_node
);
1565 * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
1566 * removed when useful for applications beyond shares distribution (e.g.
1569 #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
1570 p
->se
.avg
.runnable_avg_period
= 0;
1571 p
->se
.avg
.runnable_avg_sum
= 0;
1573 #ifdef CONFIG_SCHEDSTATS
1574 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
1577 INIT_LIST_HEAD(&p
->rt
.run_list
);
1579 #ifdef CONFIG_PREEMPT_NOTIFIERS
1580 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1583 #ifdef CONFIG_NUMA_BALANCING
1584 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
1585 p
->mm
->numa_next_scan
= jiffies
;
1586 p
->mm
->numa_next_reset
= jiffies
;
1587 p
->mm
->numa_scan_seq
= 0;
1590 p
->node_stamp
= 0ULL;
1591 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
1592 p
->numa_migrate_seq
= p
->mm
? p
->mm
->numa_scan_seq
- 1 : 0;
1593 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
1594 p
->numa_work
.next
= &p
->numa_work
;
1595 #endif /* CONFIG_NUMA_BALANCING */
1598 #ifdef CONFIG_NUMA_BALANCING
1599 #ifdef CONFIG_SCHED_DEBUG
1600 void set_numabalancing_state(bool enabled
)
1603 sched_feat_set("NUMA");
1605 sched_feat_set("NO_NUMA");
1608 __read_mostly
bool numabalancing_enabled
;
1610 void set_numabalancing_state(bool enabled
)
1612 numabalancing_enabled
= enabled
;
1614 #endif /* CONFIG_SCHED_DEBUG */
1615 #endif /* CONFIG_NUMA_BALANCING */
1618 * fork()/clone()-time setup:
1620 void sched_fork(struct task_struct
*p
)
1622 unsigned long flags
;
1623 int cpu
= get_cpu();
1627 * We mark the process as running here. This guarantees that
1628 * nobody will actually run it, and a signal or other external
1629 * event cannot wake it up and insert it on the runqueue either.
1631 p
->state
= TASK_RUNNING
;
1634 * Make sure we do not leak PI boosting priority to the child.
1636 p
->prio
= current
->normal_prio
;
1639 * Revert to default priority/policy on fork if requested.
1641 if (unlikely(p
->sched_reset_on_fork
)) {
1642 if (task_has_rt_policy(p
)) {
1643 p
->policy
= SCHED_NORMAL
;
1644 p
->static_prio
= NICE_TO_PRIO(0);
1646 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
1647 p
->static_prio
= NICE_TO_PRIO(0);
1649 p
->prio
= p
->normal_prio
= __normal_prio(p
);
1653 * We don't need the reset flag anymore after the fork. It has
1654 * fulfilled its duty:
1656 p
->sched_reset_on_fork
= 0;
1659 if (!rt_prio(p
->prio
))
1660 p
->sched_class
= &fair_sched_class
;
1662 if (p
->sched_class
->task_fork
)
1663 p
->sched_class
->task_fork(p
);
1666 * The child is not yet in the pid-hash so no cgroup attach races,
1667 * and the cgroup is pinned to this child due to cgroup_fork()
1668 * is ran before sched_fork().
1670 * Silence PROVE_RCU.
1672 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1673 set_task_cpu(p
, cpu
);
1674 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1676 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1677 if (likely(sched_info_on()))
1678 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1680 #if defined(CONFIG_SMP)
1683 #ifdef CONFIG_PREEMPT_COUNT
1684 /* Want to start with kernel preemption disabled. */
1685 task_thread_info(p
)->preempt_count
= 1;
1688 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
1695 * wake_up_new_task - wake up a newly created task for the first time.
1697 * This function will do some initial scheduler statistics housekeeping
1698 * that must be done for every newly created context, then puts the task
1699 * on the runqueue and wakes it.
1701 void wake_up_new_task(struct task_struct
*p
)
1703 unsigned long flags
;
1706 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1709 * Fork balancing, do it here and not earlier because:
1710 * - cpus_allowed can change in the fork path
1711 * - any previously selected cpu might disappear through hotplug
1713 set_task_cpu(p
, select_task_rq(p
, SD_BALANCE_FORK
, 0));
1716 rq
= __task_rq_lock(p
);
1717 activate_task(rq
, p
, 0);
1719 trace_sched_wakeup_new(p
, true);
1720 check_preempt_curr(rq
, p
, WF_FORK
);
1722 if (p
->sched_class
->task_woken
)
1723 p
->sched_class
->task_woken(rq
, p
);
1725 task_rq_unlock(rq
, p
, &flags
);
1728 #ifdef CONFIG_PREEMPT_NOTIFIERS
1731 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1732 * @notifier: notifier struct to register
1734 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1736 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1738 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1741 * preempt_notifier_unregister - no longer interested in preemption notifications
1742 * @notifier: notifier struct to unregister
1744 * This is safe to call from within a preemption notifier.
1746 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1748 hlist_del(¬ifier
->link
);
1750 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1752 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1754 struct preempt_notifier
*notifier
;
1755 struct hlist_node
*node
;
1757 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1758 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1762 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1763 struct task_struct
*next
)
1765 struct preempt_notifier
*notifier
;
1766 struct hlist_node
*node
;
1768 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1769 notifier
->ops
->sched_out(notifier
, next
);
1772 #else /* !CONFIG_PREEMPT_NOTIFIERS */
1774 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1779 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1780 struct task_struct
*next
)
1784 #endif /* CONFIG_PREEMPT_NOTIFIERS */
1787 * prepare_task_switch - prepare to switch tasks
1788 * @rq: the runqueue preparing to switch
1789 * @prev: the current task that is being switched out
1790 * @next: the task we are going to switch to.
1792 * This is called with the rq lock held and interrupts off. It must
1793 * be paired with a subsequent finish_task_switch after the context
1796 * prepare_task_switch sets up locking and calls architecture specific
1800 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1801 struct task_struct
*next
)
1803 trace_sched_switch(prev
, next
);
1804 sched_info_switch(prev
, next
);
1805 perf_event_task_sched_out(prev
, next
);
1806 fire_sched_out_preempt_notifiers(prev
, next
);
1807 prepare_lock_switch(rq
, next
);
1808 prepare_arch_switch(next
);
1812 * finish_task_switch - clean up after a task-switch
1813 * @rq: runqueue associated with task-switch
1814 * @prev: the thread we just switched away from.
1816 * finish_task_switch must be called after the context switch, paired
1817 * with a prepare_task_switch call before the context switch.
1818 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1819 * and do any other architecture-specific cleanup actions.
1821 * Note that we may have delayed dropping an mm in context_switch(). If
1822 * so, we finish that here outside of the runqueue lock. (Doing it
1823 * with the lock held can cause deadlocks; see schedule() for
1826 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1827 __releases(rq
->lock
)
1829 struct mm_struct
*mm
= rq
->prev_mm
;
1835 * A task struct has one reference for the use as "current".
1836 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1837 * schedule one last time. The schedule call will never return, and
1838 * the scheduled task must drop that reference.
1839 * The test for TASK_DEAD must occur while the runqueue locks are
1840 * still held, otherwise prev could be scheduled on another cpu, die
1841 * there before we look at prev->state, and then the reference would
1843 * Manfred Spraul <manfred@colorfullife.com>
1845 prev_state
= prev
->state
;
1846 vtime_task_switch(prev
);
1847 finish_arch_switch(prev
);
1848 perf_event_task_sched_in(prev
, current
);
1849 finish_lock_switch(rq
, prev
);
1850 finish_arch_post_lock_switch();
1852 fire_sched_in_preempt_notifiers(current
);
1855 if (unlikely(prev_state
== TASK_DEAD
)) {
1857 * Remove function-return probe instances associated with this
1858 * task and put them back on the free list.
1860 kprobe_flush_task(prev
);
1861 put_task_struct(prev
);
1867 /* assumes rq->lock is held */
1868 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*prev
)
1870 if (prev
->sched_class
->pre_schedule
)
1871 prev
->sched_class
->pre_schedule(rq
, prev
);
1874 /* rq->lock is NOT held, but preemption is disabled */
1875 static inline void post_schedule(struct rq
*rq
)
1877 if (rq
->post_schedule
) {
1878 unsigned long flags
;
1880 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1881 if (rq
->curr
->sched_class
->post_schedule
)
1882 rq
->curr
->sched_class
->post_schedule(rq
);
1883 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1885 rq
->post_schedule
= 0;
1891 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*p
)
1895 static inline void post_schedule(struct rq
*rq
)
1902 * schedule_tail - first thing a freshly forked thread must call.
1903 * @prev: the thread we just switched away from.
1905 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1906 __releases(rq
->lock
)
1908 struct rq
*rq
= this_rq();
1910 finish_task_switch(rq
, prev
);
1913 * FIXME: do we need to worry about rq being invalidated by the
1918 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1919 /* In this case, finish_task_switch does not reenable preemption */
1922 if (current
->set_child_tid
)
1923 put_user(task_pid_vnr(current
), current
->set_child_tid
);
1927 * context_switch - switch to the new MM and the new
1928 * thread's register state.
1931 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1932 struct task_struct
*next
)
1934 struct mm_struct
*mm
, *oldmm
;
1936 prepare_task_switch(rq
, prev
, next
);
1939 oldmm
= prev
->active_mm
;
1941 * For paravirt, this is coupled with an exit in switch_to to
1942 * combine the page table reload and the switch backend into
1945 arch_start_context_switch(prev
);
1948 next
->active_mm
= oldmm
;
1949 atomic_inc(&oldmm
->mm_count
);
1950 enter_lazy_tlb(oldmm
, next
);
1952 switch_mm(oldmm
, mm
, next
);
1955 prev
->active_mm
= NULL
;
1956 rq
->prev_mm
= oldmm
;
1959 * Since the runqueue lock will be released by the next
1960 * task (which is an invalid locking op but in the case
1961 * of the scheduler it's an obvious special-case), so we
1962 * do an early lockdep release here:
1964 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1965 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1968 context_tracking_task_switch(prev
, next
);
1969 /* Here we just switch the register state and the stack. */
1970 switch_to(prev
, next
, prev
);
1974 * this_rq must be evaluated again because prev may have moved
1975 * CPUs since it called schedule(), thus the 'rq' on its stack
1976 * frame will be invalid.
1978 finish_task_switch(this_rq(), prev
);
1982 * nr_running, nr_uninterruptible and nr_context_switches:
1984 * externally visible scheduler statistics: current number of runnable
1985 * threads, current number of uninterruptible-sleeping threads, total
1986 * number of context switches performed since bootup.
1988 unsigned long nr_running(void)
1990 unsigned long i
, sum
= 0;
1992 for_each_online_cpu(i
)
1993 sum
+= cpu_rq(i
)->nr_running
;
1998 unsigned long nr_uninterruptible(void)
2000 unsigned long i
, sum
= 0;
2002 for_each_possible_cpu(i
)
2003 sum
+= cpu_rq(i
)->nr_uninterruptible
;
2006 * Since we read the counters lockless, it might be slightly
2007 * inaccurate. Do not allow it to go below zero though:
2009 if (unlikely((long)sum
< 0))
2015 unsigned long long nr_context_switches(void)
2018 unsigned long long sum
= 0;
2020 for_each_possible_cpu(i
)
2021 sum
+= cpu_rq(i
)->nr_switches
;
2026 unsigned long nr_iowait(void)
2028 unsigned long i
, sum
= 0;
2030 for_each_possible_cpu(i
)
2031 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2036 unsigned long nr_iowait_cpu(int cpu
)
2038 struct rq
*this = cpu_rq(cpu
);
2039 return atomic_read(&this->nr_iowait
);
2042 unsigned long this_cpu_load(void)
2044 struct rq
*this = this_rq();
2045 return this->cpu_load
[0];
2050 * Global load-average calculations
2052 * We take a distributed and async approach to calculating the global load-avg
2053 * in order to minimize overhead.
2055 * The global load average is an exponentially decaying average of nr_running +
2056 * nr_uninterruptible.
2058 * Once every LOAD_FREQ:
2061 * for_each_possible_cpu(cpu)
2062 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible;
2064 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n)
2066 * Due to a number of reasons the above turns in the mess below:
2068 * - for_each_possible_cpu() is prohibitively expensive on machines with
2069 * serious number of cpus, therefore we need to take a distributed approach
2070 * to calculating nr_active.
2072 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0
2073 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) }
2075 * So assuming nr_active := 0 when we start out -- true per definition, we
2076 * can simply take per-cpu deltas and fold those into a global accumulate
2077 * to obtain the same result. See calc_load_fold_active().
2079 * Furthermore, in order to avoid synchronizing all per-cpu delta folding
2080 * across the machine, we assume 10 ticks is sufficient time for every
2081 * cpu to have completed this task.
2083 * This places an upper-bound on the IRQ-off latency of the machine. Then
2084 * again, being late doesn't loose the delta, just wrecks the sample.
2086 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because
2087 * this would add another cross-cpu cacheline miss and atomic operation
2088 * to the wakeup path. Instead we increment on whatever cpu the task ran
2089 * when it went into uninterruptible state and decrement on whatever cpu
2090 * did the wakeup. This means that only the sum of nr_uninterruptible over
2091 * all cpus yields the correct result.
2093 * This covers the NO_HZ=n code, for extra head-aches, see the comment below.
2096 /* Variables and functions for calc_load */
2097 static atomic_long_t calc_load_tasks
;
2098 static unsigned long calc_load_update
;
2099 unsigned long avenrun
[3];
2100 EXPORT_SYMBOL(avenrun
); /* should be removed */
2103 * get_avenrun - get the load average array
2104 * @loads: pointer to dest load array
2105 * @offset: offset to add
2106 * @shift: shift count to shift the result left
2108 * These values are estimates at best, so no need for locking.
2110 void get_avenrun(unsigned long *loads
, unsigned long offset
, int shift
)
2112 loads
[0] = (avenrun
[0] + offset
) << shift
;
2113 loads
[1] = (avenrun
[1] + offset
) << shift
;
2114 loads
[2] = (avenrun
[2] + offset
) << shift
;
2117 static long calc_load_fold_active(struct rq
*this_rq
)
2119 long nr_active
, delta
= 0;
2121 nr_active
= this_rq
->nr_running
;
2122 nr_active
+= (long) this_rq
->nr_uninterruptible
;
2124 if (nr_active
!= this_rq
->calc_load_active
) {
2125 delta
= nr_active
- this_rq
->calc_load_active
;
2126 this_rq
->calc_load_active
= nr_active
;
2133 * a1 = a0 * e + a * (1 - e)
2135 static unsigned long
2136 calc_load(unsigned long load
, unsigned long exp
, unsigned long active
)
2139 load
+= active
* (FIXED_1
- exp
);
2140 load
+= 1UL << (FSHIFT
- 1);
2141 return load
>> FSHIFT
;
2146 * Handle NO_HZ for the global load-average.
2148 * Since the above described distributed algorithm to compute the global
2149 * load-average relies on per-cpu sampling from the tick, it is affected by
2152 * The basic idea is to fold the nr_active delta into a global idle-delta upon
2153 * entering NO_HZ state such that we can include this as an 'extra' cpu delta
2154 * when we read the global state.
2156 * Obviously reality has to ruin such a delightfully simple scheme:
2158 * - When we go NO_HZ idle during the window, we can negate our sample
2159 * contribution, causing under-accounting.
2161 * We avoid this by keeping two idle-delta counters and flipping them
2162 * when the window starts, thus separating old and new NO_HZ load.
2164 * The only trick is the slight shift in index flip for read vs write.
2168 * |-|-----------|-|-----------|-|-----------|-|
2169 * r:0 0 1 1 0 0 1 1 0
2170 * w:0 1 1 0 0 1 1 0 0
2172 * This ensures we'll fold the old idle contribution in this window while
2173 * accumlating the new one.
2175 * - When we wake up from NO_HZ idle during the window, we push up our
2176 * contribution, since we effectively move our sample point to a known
2179 * This is solved by pushing the window forward, and thus skipping the
2180 * sample, for this cpu (effectively using the idle-delta for this cpu which
2181 * was in effect at the time the window opened). This also solves the issue
2182 * of having to deal with a cpu having been in NOHZ idle for multiple
2183 * LOAD_FREQ intervals.
2185 * When making the ILB scale, we should try to pull this in as well.
2187 static atomic_long_t calc_load_idle
[2];
2188 static int calc_load_idx
;
2190 static inline int calc_load_write_idx(void)
2192 int idx
= calc_load_idx
;
2195 * See calc_global_nohz(), if we observe the new index, we also
2196 * need to observe the new update time.
2201 * If the folding window started, make sure we start writing in the
2204 if (!time_before(jiffies
, calc_load_update
))
2210 static inline int calc_load_read_idx(void)
2212 return calc_load_idx
& 1;
2215 void calc_load_enter_idle(void)
2217 struct rq
*this_rq
= this_rq();
2221 * We're going into NOHZ mode, if there's any pending delta, fold it
2222 * into the pending idle delta.
2224 delta
= calc_load_fold_active(this_rq
);
2226 int idx
= calc_load_write_idx();
2227 atomic_long_add(delta
, &calc_load_idle
[idx
]);
2231 void calc_load_exit_idle(void)
2233 struct rq
*this_rq
= this_rq();
2236 * If we're still before the sample window, we're done.
2238 if (time_before(jiffies
, this_rq
->calc_load_update
))
2242 * We woke inside or after the sample window, this means we're already
2243 * accounted through the nohz accounting, so skip the entire deal and
2244 * sync up for the next window.
2246 this_rq
->calc_load_update
= calc_load_update
;
2247 if (time_before(jiffies
, this_rq
->calc_load_update
+ 10))
2248 this_rq
->calc_load_update
+= LOAD_FREQ
;
2251 static long calc_load_fold_idle(void)
2253 int idx
= calc_load_read_idx();
2256 if (atomic_long_read(&calc_load_idle
[idx
]))
2257 delta
= atomic_long_xchg(&calc_load_idle
[idx
], 0);
2263 * fixed_power_int - compute: x^n, in O(log n) time
2265 * @x: base of the power
2266 * @frac_bits: fractional bits of @x
2267 * @n: power to raise @x to.
2269 * By exploiting the relation between the definition of the natural power
2270 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
2271 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
2272 * (where: n_i \elem {0, 1}, the binary vector representing n),
2273 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
2274 * of course trivially computable in O(log_2 n), the length of our binary
2277 static unsigned long
2278 fixed_power_int(unsigned long x
, unsigned int frac_bits
, unsigned int n
)
2280 unsigned long result
= 1UL << frac_bits
;
2285 result
+= 1UL << (frac_bits
- 1);
2286 result
>>= frac_bits
;
2292 x
+= 1UL << (frac_bits
- 1);
2300 * a1 = a0 * e + a * (1 - e)
2302 * a2 = a1 * e + a * (1 - e)
2303 * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
2304 * = a0 * e^2 + a * (1 - e) * (1 + e)
2306 * a3 = a2 * e + a * (1 - e)
2307 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
2308 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
2312 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
2313 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
2314 * = a0 * e^n + a * (1 - e^n)
2316 * [1] application of the geometric series:
2319 * S_n := \Sum x^i = -------------
2322 static unsigned long
2323 calc_load_n(unsigned long load
, unsigned long exp
,
2324 unsigned long active
, unsigned int n
)
2327 return calc_load(load
, fixed_power_int(exp
, FSHIFT
, n
), active
);
2331 * NO_HZ can leave us missing all per-cpu ticks calling
2332 * calc_load_account_active(), but since an idle CPU folds its delta into
2333 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
2334 * in the pending idle delta if our idle period crossed a load cycle boundary.
2336 * Once we've updated the global active value, we need to apply the exponential
2337 * weights adjusted to the number of cycles missed.
2339 static void calc_global_nohz(void)
2341 long delta
, active
, n
;
2343 if (!time_before(jiffies
, calc_load_update
+ 10)) {
2345 * Catch-up, fold however many we are behind still
2347 delta
= jiffies
- calc_load_update
- 10;
2348 n
= 1 + (delta
/ LOAD_FREQ
);
2350 active
= atomic_long_read(&calc_load_tasks
);
2351 active
= active
> 0 ? active
* FIXED_1
: 0;
2353 avenrun
[0] = calc_load_n(avenrun
[0], EXP_1
, active
, n
);
2354 avenrun
[1] = calc_load_n(avenrun
[1], EXP_5
, active
, n
);
2355 avenrun
[2] = calc_load_n(avenrun
[2], EXP_15
, active
, n
);
2357 calc_load_update
+= n
* LOAD_FREQ
;
2361 * Flip the idle index...
2363 * Make sure we first write the new time then flip the index, so that
2364 * calc_load_write_idx() will see the new time when it reads the new
2365 * index, this avoids a double flip messing things up.
2370 #else /* !CONFIG_NO_HZ */
2372 static inline long calc_load_fold_idle(void) { return 0; }
2373 static inline void calc_global_nohz(void) { }
2375 #endif /* CONFIG_NO_HZ */
2378 * calc_load - update the avenrun load estimates 10 ticks after the
2379 * CPUs have updated calc_load_tasks.
2381 void calc_global_load(unsigned long ticks
)
2385 if (time_before(jiffies
, calc_load_update
+ 10))
2389 * Fold the 'old' idle-delta to include all NO_HZ cpus.
2391 delta
= calc_load_fold_idle();
2393 atomic_long_add(delta
, &calc_load_tasks
);
2395 active
= atomic_long_read(&calc_load_tasks
);
2396 active
= active
> 0 ? active
* FIXED_1
: 0;
2398 avenrun
[0] = calc_load(avenrun
[0], EXP_1
, active
);
2399 avenrun
[1] = calc_load(avenrun
[1], EXP_5
, active
);
2400 avenrun
[2] = calc_load(avenrun
[2], EXP_15
, active
);
2402 calc_load_update
+= LOAD_FREQ
;
2405 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk.
2411 * Called from update_cpu_load() to periodically update this CPU's
2414 static void calc_load_account_active(struct rq
*this_rq
)
2418 if (time_before(jiffies
, this_rq
->calc_load_update
))
2421 delta
= calc_load_fold_active(this_rq
);
2423 atomic_long_add(delta
, &calc_load_tasks
);
2425 this_rq
->calc_load_update
+= LOAD_FREQ
;
2429 * End of global load-average stuff
2433 * The exact cpuload at various idx values, calculated at every tick would be
2434 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
2436 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
2437 * on nth tick when cpu may be busy, then we have:
2438 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2439 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
2441 * decay_load_missed() below does efficient calculation of
2442 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2443 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
2445 * The calculation is approximated on a 128 point scale.
2446 * degrade_zero_ticks is the number of ticks after which load at any
2447 * particular idx is approximated to be zero.
2448 * degrade_factor is a precomputed table, a row for each load idx.
2449 * Each column corresponds to degradation factor for a power of two ticks,
2450 * based on 128 point scale.
2452 * row 2, col 3 (=12) says that the degradation at load idx 2 after
2453 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
2455 * With this power of 2 load factors, we can degrade the load n times
2456 * by looking at 1 bits in n and doing as many mult/shift instead of
2457 * n mult/shifts needed by the exact degradation.
2459 #define DEGRADE_SHIFT 7
2460 static const unsigned char
2461 degrade_zero_ticks
[CPU_LOAD_IDX_MAX
] = {0, 8, 32, 64, 128};
2462 static const unsigned char
2463 degrade_factor
[CPU_LOAD_IDX_MAX
][DEGRADE_SHIFT
+ 1] = {
2464 {0, 0, 0, 0, 0, 0, 0, 0},
2465 {64, 32, 8, 0, 0, 0, 0, 0},
2466 {96, 72, 40, 12, 1, 0, 0},
2467 {112, 98, 75, 43, 15, 1, 0},
2468 {120, 112, 98, 76, 45, 16, 2} };
2471 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
2472 * would be when CPU is idle and so we just decay the old load without
2473 * adding any new load.
2475 static unsigned long
2476 decay_load_missed(unsigned long load
, unsigned long missed_updates
, int idx
)
2480 if (!missed_updates
)
2483 if (missed_updates
>= degrade_zero_ticks
[idx
])
2487 return load
>> missed_updates
;
2489 while (missed_updates
) {
2490 if (missed_updates
% 2)
2491 load
= (load
* degrade_factor
[idx
][j
]) >> DEGRADE_SHIFT
;
2493 missed_updates
>>= 1;
2500 * Update rq->cpu_load[] statistics. This function is usually called every
2501 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
2502 * every tick. We fix it up based on jiffies.
2504 static void __update_cpu_load(struct rq
*this_rq
, unsigned long this_load
,
2505 unsigned long pending_updates
)
2509 this_rq
->nr_load_updates
++;
2511 /* Update our load: */
2512 this_rq
->cpu_load
[0] = this_load
; /* Fasttrack for idx 0 */
2513 for (i
= 1, scale
= 2; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2514 unsigned long old_load
, new_load
;
2516 /* scale is effectively 1 << i now, and >> i divides by scale */
2518 old_load
= this_rq
->cpu_load
[i
];
2519 old_load
= decay_load_missed(old_load
, pending_updates
- 1, i
);
2520 new_load
= this_load
;
2522 * Round up the averaging division if load is increasing. This
2523 * prevents us from getting stuck on 9 if the load is 10, for
2526 if (new_load
> old_load
)
2527 new_load
+= scale
- 1;
2529 this_rq
->cpu_load
[i
] = (old_load
* (scale
- 1) + new_load
) >> i
;
2532 sched_avg_update(this_rq
);
2537 * There is no sane way to deal with nohz on smp when using jiffies because the
2538 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
2539 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
2541 * Therefore we cannot use the delta approach from the regular tick since that
2542 * would seriously skew the load calculation. However we'll make do for those
2543 * updates happening while idle (nohz_idle_balance) or coming out of idle
2544 * (tick_nohz_idle_exit).
2546 * This means we might still be one tick off for nohz periods.
2550 * Called from nohz_idle_balance() to update the load ratings before doing the
2553 void update_idle_cpu_load(struct rq
*this_rq
)
2555 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2556 unsigned long load
= this_rq
->load
.weight
;
2557 unsigned long pending_updates
;
2560 * bail if there's load or we're actually up-to-date.
2562 if (load
|| curr_jiffies
== this_rq
->last_load_update_tick
)
2565 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2566 this_rq
->last_load_update_tick
= curr_jiffies
;
2568 __update_cpu_load(this_rq
, load
, pending_updates
);
2572 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
2574 void update_cpu_load_nohz(void)
2576 struct rq
*this_rq
= this_rq();
2577 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2578 unsigned long pending_updates
;
2580 if (curr_jiffies
== this_rq
->last_load_update_tick
)
2583 raw_spin_lock(&this_rq
->lock
);
2584 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2585 if (pending_updates
) {
2586 this_rq
->last_load_update_tick
= curr_jiffies
;
2588 * We were idle, this means load 0, the current load might be
2589 * !0 due to remote wakeups and the sort.
2591 __update_cpu_load(this_rq
, 0, pending_updates
);
2593 raw_spin_unlock(&this_rq
->lock
);
2595 #endif /* CONFIG_NO_HZ */
2598 * Called from scheduler_tick()
2600 static void update_cpu_load_active(struct rq
*this_rq
)
2603 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
2605 this_rq
->last_load_update_tick
= jiffies
;
2606 __update_cpu_load(this_rq
, this_rq
->load
.weight
, 1);
2608 calc_load_account_active(this_rq
);
2614 * sched_exec - execve() is a valuable balancing opportunity, because at
2615 * this point the task has the smallest effective memory and cache footprint.
2617 void sched_exec(void)
2619 struct task_struct
*p
= current
;
2620 unsigned long flags
;
2623 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2624 dest_cpu
= p
->sched_class
->select_task_rq(p
, SD_BALANCE_EXEC
, 0);
2625 if (dest_cpu
== smp_processor_id())
2628 if (likely(cpu_active(dest_cpu
))) {
2629 struct migration_arg arg
= { p
, dest_cpu
};
2631 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2632 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2636 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2641 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2642 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2644 EXPORT_PER_CPU_SYMBOL(kstat
);
2645 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2648 * Return any ns on the sched_clock that have not yet been accounted in
2649 * @p in case that task is currently running.
2651 * Called with task_rq_lock() held on @rq.
2653 static u64
do_task_delta_exec(struct task_struct
*p
, struct rq
*rq
)
2657 if (task_current(rq
, p
)) {
2658 update_rq_clock(rq
);
2659 ns
= rq
->clock_task
- p
->se
.exec_start
;
2667 unsigned long long task_delta_exec(struct task_struct
*p
)
2669 unsigned long flags
;
2673 rq
= task_rq_lock(p
, &flags
);
2674 ns
= do_task_delta_exec(p
, rq
);
2675 task_rq_unlock(rq
, p
, &flags
);
2681 * Return accounted runtime for the task.
2682 * In case the task is currently running, return the runtime plus current's
2683 * pending runtime that have not been accounted yet.
2685 unsigned long long task_sched_runtime(struct task_struct
*p
)
2687 unsigned long flags
;
2691 rq
= task_rq_lock(p
, &flags
);
2692 ns
= p
->se
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
2693 task_rq_unlock(rq
, p
, &flags
);
2699 * This function gets called by the timer code, with HZ frequency.
2700 * We call it with interrupts disabled.
2702 void scheduler_tick(void)
2704 int cpu
= smp_processor_id();
2705 struct rq
*rq
= cpu_rq(cpu
);
2706 struct task_struct
*curr
= rq
->curr
;
2710 raw_spin_lock(&rq
->lock
);
2711 update_rq_clock(rq
);
2712 update_cpu_load_active(rq
);
2713 curr
->sched_class
->task_tick(rq
, curr
, 0);
2714 raw_spin_unlock(&rq
->lock
);
2716 perf_event_task_tick();
2719 rq
->idle_balance
= idle_cpu(cpu
);
2720 trigger_load_balance(rq
, cpu
);
2724 notrace
unsigned long get_parent_ip(unsigned long addr
)
2726 if (in_lock_functions(addr
)) {
2727 addr
= CALLER_ADDR2
;
2728 if (in_lock_functions(addr
))
2729 addr
= CALLER_ADDR3
;
2734 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2735 defined(CONFIG_PREEMPT_TRACER))
2737 void __kprobes
add_preempt_count(int val
)
2739 #ifdef CONFIG_DEBUG_PREEMPT
2743 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2746 preempt_count() += val
;
2747 #ifdef CONFIG_DEBUG_PREEMPT
2749 * Spinlock count overflowing soon?
2751 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
2754 if (preempt_count() == val
)
2755 trace_preempt_off(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2757 EXPORT_SYMBOL(add_preempt_count
);
2759 void __kprobes
sub_preempt_count(int val
)
2761 #ifdef CONFIG_DEBUG_PREEMPT
2765 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
2768 * Is the spinlock portion underflowing?
2770 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
2771 !(preempt_count() & PREEMPT_MASK
)))
2775 if (preempt_count() == val
)
2776 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2777 preempt_count() -= val
;
2779 EXPORT_SYMBOL(sub_preempt_count
);
2784 * Print scheduling while atomic bug:
2786 static noinline
void __schedule_bug(struct task_struct
*prev
)
2788 if (oops_in_progress
)
2791 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
2792 prev
->comm
, prev
->pid
, preempt_count());
2794 debug_show_held_locks(prev
);
2796 if (irqs_disabled())
2797 print_irqtrace_events(prev
);
2799 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
2803 * Various schedule()-time debugging checks and statistics:
2805 static inline void schedule_debug(struct task_struct
*prev
)
2808 * Test if we are atomic. Since do_exit() needs to call into
2809 * schedule() atomically, we ignore that path for now.
2810 * Otherwise, whine if we are scheduling when we should not be.
2812 if (unlikely(in_atomic_preempt_off() && !prev
->exit_state
))
2813 __schedule_bug(prev
);
2816 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2818 schedstat_inc(this_rq(), sched_count
);
2821 static void put_prev_task(struct rq
*rq
, struct task_struct
*prev
)
2823 if (prev
->on_rq
|| rq
->skip_clock_update
< 0)
2824 update_rq_clock(rq
);
2825 prev
->sched_class
->put_prev_task(rq
, prev
);
2829 * Pick up the highest-prio task:
2831 static inline struct task_struct
*
2832 pick_next_task(struct rq
*rq
)
2834 const struct sched_class
*class;
2835 struct task_struct
*p
;
2838 * Optimization: we know that if all tasks are in
2839 * the fair class we can call that function directly:
2841 if (likely(rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
2842 p
= fair_sched_class
.pick_next_task(rq
);
2847 for_each_class(class) {
2848 p
= class->pick_next_task(rq
);
2853 BUG(); /* the idle class will always have a runnable task */
2857 * __schedule() is the main scheduler function.
2859 * The main means of driving the scheduler and thus entering this function are:
2861 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2863 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2864 * paths. For example, see arch/x86/entry_64.S.
2866 * To drive preemption between tasks, the scheduler sets the flag in timer
2867 * interrupt handler scheduler_tick().
2869 * 3. Wakeups don't really cause entry into schedule(). They add a
2870 * task to the run-queue and that's it.
2872 * Now, if the new task added to the run-queue preempts the current
2873 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2874 * called on the nearest possible occasion:
2876 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2878 * - in syscall or exception context, at the next outmost
2879 * preempt_enable(). (this might be as soon as the wake_up()'s
2882 * - in IRQ context, return from interrupt-handler to
2883 * preemptible context
2885 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2888 * - cond_resched() call
2889 * - explicit schedule() call
2890 * - return from syscall or exception to user-space
2891 * - return from interrupt-handler to user-space
2893 static void __sched
__schedule(void)
2895 struct task_struct
*prev
, *next
;
2896 unsigned long *switch_count
;
2902 cpu
= smp_processor_id();
2904 rcu_note_context_switch(cpu
);
2907 schedule_debug(prev
);
2909 if (sched_feat(HRTICK
))
2912 raw_spin_lock_irq(&rq
->lock
);
2914 switch_count
= &prev
->nivcsw
;
2915 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2916 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
2917 prev
->state
= TASK_RUNNING
;
2919 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
2923 * If a worker went to sleep, notify and ask workqueue
2924 * whether it wants to wake up a task to maintain
2927 if (prev
->flags
& PF_WQ_WORKER
) {
2928 struct task_struct
*to_wakeup
;
2930 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
2932 try_to_wake_up_local(to_wakeup
);
2935 switch_count
= &prev
->nvcsw
;
2938 pre_schedule(rq
, prev
);
2940 if (unlikely(!rq
->nr_running
))
2941 idle_balance(cpu
, rq
);
2943 put_prev_task(rq
, prev
);
2944 next
= pick_next_task(rq
);
2945 clear_tsk_need_resched(prev
);
2946 rq
->skip_clock_update
= 0;
2948 if (likely(prev
!= next
)) {
2953 context_switch(rq
, prev
, next
); /* unlocks the rq */
2955 * The context switch have flipped the stack from under us
2956 * and restored the local variables which were saved when
2957 * this task called schedule() in the past. prev == current
2958 * is still correct, but it can be moved to another cpu/rq.
2960 cpu
= smp_processor_id();
2963 raw_spin_unlock_irq(&rq
->lock
);
2967 sched_preempt_enable_no_resched();
2972 static inline void sched_submit_work(struct task_struct
*tsk
)
2974 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
2977 * If we are going to sleep and we have plugged IO queued,
2978 * make sure to submit it to avoid deadlocks.
2980 if (blk_needs_flush_plug(tsk
))
2981 blk_schedule_flush_plug(tsk
);
2984 asmlinkage
void __sched
schedule(void)
2986 struct task_struct
*tsk
= current
;
2988 sched_submit_work(tsk
);
2991 EXPORT_SYMBOL(schedule
);
2993 #ifdef CONFIG_CONTEXT_TRACKING
2994 asmlinkage
void __sched
schedule_user(void)
2997 * If we come here after a random call to set_need_resched(),
2998 * or we have been woken up remotely but the IPI has not yet arrived,
2999 * we haven't yet exited the RCU idle mode. Do it here manually until
3000 * we find a better solution.
3009 * schedule_preempt_disabled - called with preemption disabled
3011 * Returns with preemption disabled. Note: preempt_count must be 1
3013 void __sched
schedule_preempt_disabled(void)
3015 sched_preempt_enable_no_resched();
3020 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
3022 static inline bool owner_running(struct mutex
*lock
, struct task_struct
*owner
)
3024 if (lock
->owner
!= owner
)
3028 * Ensure we emit the owner->on_cpu, dereference _after_ checking
3029 * lock->owner still matches owner, if that fails, owner might
3030 * point to free()d memory, if it still matches, the rcu_read_lock()
3031 * ensures the memory stays valid.
3035 return owner
->on_cpu
;
3039 * Look out! "owner" is an entirely speculative pointer
3040 * access and not reliable.
3042 int mutex_spin_on_owner(struct mutex
*lock
, struct task_struct
*owner
)
3044 if (!sched_feat(OWNER_SPIN
))
3048 while (owner_running(lock
, owner
)) {
3052 arch_mutex_cpu_relax();
3057 * We break out the loop above on need_resched() and when the
3058 * owner changed, which is a sign for heavy contention. Return
3059 * success only when lock->owner is NULL.
3061 return lock
->owner
== NULL
;
3065 #ifdef CONFIG_PREEMPT
3067 * this is the entry point to schedule() from in-kernel preemption
3068 * off of preempt_enable. Kernel preemptions off return from interrupt
3069 * occur there and call schedule directly.
3071 asmlinkage
void __sched notrace
preempt_schedule(void)
3073 struct thread_info
*ti
= current_thread_info();
3076 * If there is a non-zero preempt_count or interrupts are disabled,
3077 * we do not want to preempt the current task. Just return..
3079 if (likely(ti
->preempt_count
|| irqs_disabled()))
3083 add_preempt_count_notrace(PREEMPT_ACTIVE
);
3085 sub_preempt_count_notrace(PREEMPT_ACTIVE
);
3088 * Check again in case we missed a preemption opportunity
3089 * between schedule and now.
3092 } while (need_resched());
3094 EXPORT_SYMBOL(preempt_schedule
);
3097 * this is the entry point to schedule() from kernel preemption
3098 * off of irq context.
3099 * Note, that this is called and return with irqs disabled. This will
3100 * protect us against recursive calling from irq.
3102 asmlinkage
void __sched
preempt_schedule_irq(void)
3104 struct thread_info
*ti
= current_thread_info();
3106 /* Catch callers which need to be fixed */
3107 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3111 add_preempt_count(PREEMPT_ACTIVE
);
3114 local_irq_disable();
3115 sub_preempt_count(PREEMPT_ACTIVE
);
3118 * Check again in case we missed a preemption opportunity
3119 * between schedule and now.
3122 } while (need_resched());
3125 #endif /* CONFIG_PREEMPT */
3127 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
3130 return try_to_wake_up(curr
->private, mode
, wake_flags
);
3132 EXPORT_SYMBOL(default_wake_function
);
3135 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3136 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3137 * number) then we wake all the non-exclusive tasks and one exclusive task.
3139 * There are circumstances in which we can try to wake a task which has already
3140 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3141 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3143 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3144 int nr_exclusive
, int wake_flags
, void *key
)
3146 wait_queue_t
*curr
, *next
;
3148 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3149 unsigned flags
= curr
->flags
;
3151 if (curr
->func(curr
, mode
, wake_flags
, key
) &&
3152 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3158 * __wake_up - wake up threads blocked on a waitqueue.
3160 * @mode: which threads
3161 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3162 * @key: is directly passed to the wakeup function
3164 * It may be assumed that this function implies a write memory barrier before
3165 * changing the task state if and only if any tasks are woken up.
3167 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3168 int nr_exclusive
, void *key
)
3170 unsigned long flags
;
3172 spin_lock_irqsave(&q
->lock
, flags
);
3173 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3174 spin_unlock_irqrestore(&q
->lock
, flags
);
3176 EXPORT_SYMBOL(__wake_up
);
3179 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3181 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
, int nr
)
3183 __wake_up_common(q
, mode
, nr
, 0, NULL
);
3185 EXPORT_SYMBOL_GPL(__wake_up_locked
);
3187 void __wake_up_locked_key(wait_queue_head_t
*q
, unsigned int mode
, void *key
)
3189 __wake_up_common(q
, mode
, 1, 0, key
);
3191 EXPORT_SYMBOL_GPL(__wake_up_locked_key
);
3194 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
3196 * @mode: which threads
3197 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3198 * @key: opaque value to be passed to wakeup targets
3200 * The sync wakeup differs that the waker knows that it will schedule
3201 * away soon, so while the target thread will be woken up, it will not
3202 * be migrated to another CPU - ie. the two threads are 'synchronized'
3203 * with each other. This can prevent needless bouncing between CPUs.
3205 * On UP it can prevent extra preemption.
3207 * It may be assumed that this function implies a write memory barrier before
3208 * changing the task state if and only if any tasks are woken up.
3210 void __wake_up_sync_key(wait_queue_head_t
*q
, unsigned int mode
,
3211 int nr_exclusive
, void *key
)
3213 unsigned long flags
;
3214 int wake_flags
= WF_SYNC
;
3219 if (unlikely(!nr_exclusive
))
3222 spin_lock_irqsave(&q
->lock
, flags
);
3223 __wake_up_common(q
, mode
, nr_exclusive
, wake_flags
, key
);
3224 spin_unlock_irqrestore(&q
->lock
, flags
);
3226 EXPORT_SYMBOL_GPL(__wake_up_sync_key
);
3229 * __wake_up_sync - see __wake_up_sync_key()
3231 void __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3233 __wake_up_sync_key(q
, mode
, nr_exclusive
, NULL
);
3235 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3238 * complete: - signals a single thread waiting on this completion
3239 * @x: holds the state of this particular completion
3241 * This will wake up a single thread waiting on this completion. Threads will be
3242 * awakened in the same order in which they were queued.
3244 * See also complete_all(), wait_for_completion() and related routines.
3246 * It may be assumed that this function implies a write memory barrier before
3247 * changing the task state if and only if any tasks are woken up.
3249 void complete(struct completion
*x
)
3251 unsigned long flags
;
3253 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3255 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
3256 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3258 EXPORT_SYMBOL(complete
);
3261 * complete_all: - signals all threads waiting on this completion
3262 * @x: holds the state of this particular completion
3264 * This will wake up all threads waiting on this particular completion event.
3266 * It may be assumed that this function implies a write memory barrier before
3267 * changing the task state if and only if any tasks are woken up.
3269 void complete_all(struct completion
*x
)
3271 unsigned long flags
;
3273 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3274 x
->done
+= UINT_MAX
/2;
3275 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
3276 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3278 EXPORT_SYMBOL(complete_all
);
3280 static inline long __sched
3281 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
3284 DECLARE_WAITQUEUE(wait
, current
);
3286 __add_wait_queue_tail_exclusive(&x
->wait
, &wait
);
3288 if (signal_pending_state(state
, current
)) {
3289 timeout
= -ERESTARTSYS
;
3292 __set_current_state(state
);
3293 spin_unlock_irq(&x
->wait
.lock
);
3294 timeout
= schedule_timeout(timeout
);
3295 spin_lock_irq(&x
->wait
.lock
);
3296 } while (!x
->done
&& timeout
);
3297 __remove_wait_queue(&x
->wait
, &wait
);
3302 return timeout
?: 1;
3306 wait_for_common(struct completion
*x
, long timeout
, int state
)
3310 spin_lock_irq(&x
->wait
.lock
);
3311 timeout
= do_wait_for_common(x
, timeout
, state
);
3312 spin_unlock_irq(&x
->wait
.lock
);
3317 * wait_for_completion: - waits for completion of a task
3318 * @x: holds the state of this particular completion
3320 * This waits to be signaled for completion of a specific task. It is NOT
3321 * interruptible and there is no timeout.
3323 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
3324 * and interrupt capability. Also see complete().
3326 void __sched
wait_for_completion(struct completion
*x
)
3328 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3330 EXPORT_SYMBOL(wait_for_completion
);
3333 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
3334 * @x: holds the state of this particular completion
3335 * @timeout: timeout value in jiffies
3337 * This waits for either a completion of a specific task to be signaled or for a
3338 * specified timeout to expire. The timeout is in jiffies. It is not
3341 * The return value is 0 if timed out, and positive (at least 1, or number of
3342 * jiffies left till timeout) if completed.
3344 unsigned long __sched
3345 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3347 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3349 EXPORT_SYMBOL(wait_for_completion_timeout
);
3352 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
3353 * @x: holds the state of this particular completion
3355 * This waits for completion of a specific task to be signaled. It is
3358 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3360 int __sched
wait_for_completion_interruptible(struct completion
*x
)
3362 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
3363 if (t
== -ERESTARTSYS
)
3367 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3370 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
3371 * @x: holds the state of this particular completion
3372 * @timeout: timeout value in jiffies
3374 * This waits for either a completion of a specific task to be signaled or for a
3375 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
3377 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3378 * positive (at least 1, or number of jiffies left till timeout) if completed.
3381 wait_for_completion_interruptible_timeout(struct completion
*x
,
3382 unsigned long timeout
)
3384 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
3386 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3389 * wait_for_completion_killable: - waits for completion of a task (killable)
3390 * @x: holds the state of this particular completion
3392 * This waits to be signaled for completion of a specific task. It can be
3393 * interrupted by a kill signal.
3395 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3397 int __sched
wait_for_completion_killable(struct completion
*x
)
3399 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
3400 if (t
== -ERESTARTSYS
)
3404 EXPORT_SYMBOL(wait_for_completion_killable
);
3407 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
3408 * @x: holds the state of this particular completion
3409 * @timeout: timeout value in jiffies
3411 * This waits for either a completion of a specific task to be
3412 * signaled or for a specified timeout to expire. It can be
3413 * interrupted by a kill signal. The timeout is in jiffies.
3415 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3416 * positive (at least 1, or number of jiffies left till timeout) if completed.
3419 wait_for_completion_killable_timeout(struct completion
*x
,
3420 unsigned long timeout
)
3422 return wait_for_common(x
, timeout
, TASK_KILLABLE
);
3424 EXPORT_SYMBOL(wait_for_completion_killable_timeout
);
3427 * try_wait_for_completion - try to decrement a completion without blocking
3428 * @x: completion structure
3430 * Returns: 0 if a decrement cannot be done without blocking
3431 * 1 if a decrement succeeded.
3433 * If a completion is being used as a counting completion,
3434 * attempt to decrement the counter without blocking. This
3435 * enables us to avoid waiting if the resource the completion
3436 * is protecting is not available.
3438 bool try_wait_for_completion(struct completion
*x
)
3440 unsigned long flags
;
3443 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3448 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3451 EXPORT_SYMBOL(try_wait_for_completion
);
3454 * completion_done - Test to see if a completion has any waiters
3455 * @x: completion structure
3457 * Returns: 0 if there are waiters (wait_for_completion() in progress)
3458 * 1 if there are no waiters.
3461 bool completion_done(struct completion
*x
)
3463 unsigned long flags
;
3466 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3469 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3472 EXPORT_SYMBOL(completion_done
);
3475 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
3477 unsigned long flags
;
3480 init_waitqueue_entry(&wait
, current
);
3482 __set_current_state(state
);
3484 spin_lock_irqsave(&q
->lock
, flags
);
3485 __add_wait_queue(q
, &wait
);
3486 spin_unlock(&q
->lock
);
3487 timeout
= schedule_timeout(timeout
);
3488 spin_lock_irq(&q
->lock
);
3489 __remove_wait_queue(q
, &wait
);
3490 spin_unlock_irqrestore(&q
->lock
, flags
);
3495 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3497 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3499 EXPORT_SYMBOL(interruptible_sleep_on
);
3502 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3504 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
3506 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3508 void __sched
sleep_on(wait_queue_head_t
*q
)
3510 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3512 EXPORT_SYMBOL(sleep_on
);
3514 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3516 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
3518 EXPORT_SYMBOL(sleep_on_timeout
);
3520 #ifdef CONFIG_RT_MUTEXES
3523 * rt_mutex_setprio - set the current priority of a task
3525 * @prio: prio value (kernel-internal form)
3527 * This function changes the 'effective' priority of a task. It does
3528 * not touch ->normal_prio like __setscheduler().
3530 * Used by the rt_mutex code to implement priority inheritance logic.
3532 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3534 int oldprio
, on_rq
, running
;
3536 const struct sched_class
*prev_class
;
3538 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3540 rq
= __task_rq_lock(p
);
3543 * Idle task boosting is a nono in general. There is one
3544 * exception, when PREEMPT_RT and NOHZ is active:
3546 * The idle task calls get_next_timer_interrupt() and holds
3547 * the timer wheel base->lock on the CPU and another CPU wants
3548 * to access the timer (probably to cancel it). We can safely
3549 * ignore the boosting request, as the idle CPU runs this code
3550 * with interrupts disabled and will complete the lock
3551 * protected section without being interrupted. So there is no
3552 * real need to boost.
3554 if (unlikely(p
== rq
->idle
)) {
3555 WARN_ON(p
!= rq
->curr
);
3556 WARN_ON(p
->pi_blocked_on
);
3560 trace_sched_pi_setprio(p
, prio
);
3562 prev_class
= p
->sched_class
;
3564 running
= task_current(rq
, p
);
3566 dequeue_task(rq
, p
, 0);
3568 p
->sched_class
->put_prev_task(rq
, p
);
3571 p
->sched_class
= &rt_sched_class
;
3573 p
->sched_class
= &fair_sched_class
;
3578 p
->sched_class
->set_curr_task(rq
);
3580 enqueue_task(rq
, p
, oldprio
< prio
? ENQUEUE_HEAD
: 0);
3582 check_class_changed(rq
, p
, prev_class
, oldprio
);
3584 __task_rq_unlock(rq
);
3587 void set_user_nice(struct task_struct
*p
, long nice
)
3589 int old_prio
, delta
, on_rq
;
3590 unsigned long flags
;
3593 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3596 * We have to be careful, if called from sys_setpriority(),
3597 * the task might be in the middle of scheduling on another CPU.
3599 rq
= task_rq_lock(p
, &flags
);
3601 * The RT priorities are set via sched_setscheduler(), but we still
3602 * allow the 'normal' nice value to be set - but as expected
3603 * it wont have any effect on scheduling until the task is
3604 * SCHED_FIFO/SCHED_RR:
3606 if (task_has_rt_policy(p
)) {
3607 p
->static_prio
= NICE_TO_PRIO(nice
);
3612 dequeue_task(rq
, p
, 0);
3614 p
->static_prio
= NICE_TO_PRIO(nice
);
3617 p
->prio
= effective_prio(p
);
3618 delta
= p
->prio
- old_prio
;
3621 enqueue_task(rq
, p
, 0);
3623 * If the task increased its priority or is running and
3624 * lowered its priority, then reschedule its CPU:
3626 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3627 resched_task(rq
->curr
);
3630 task_rq_unlock(rq
, p
, &flags
);
3632 EXPORT_SYMBOL(set_user_nice
);
3635 * can_nice - check if a task can reduce its nice value
3639 int can_nice(const struct task_struct
*p
, const int nice
)
3641 /* convert nice value [19,-20] to rlimit style value [1,40] */
3642 int nice_rlim
= 20 - nice
;
3644 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3645 capable(CAP_SYS_NICE
));
3648 #ifdef __ARCH_WANT_SYS_NICE
3651 * sys_nice - change the priority of the current process.
3652 * @increment: priority increment
3654 * sys_setpriority is a more generic, but much slower function that
3655 * does similar things.
3657 SYSCALL_DEFINE1(nice
, int, increment
)
3662 * Setpriority might change our priority at the same moment.
3663 * We don't have to worry. Conceptually one call occurs first
3664 * and we have a single winner.
3666 if (increment
< -40)
3671 nice
= TASK_NICE(current
) + increment
;
3677 if (increment
< 0 && !can_nice(current
, nice
))
3680 retval
= security_task_setnice(current
, nice
);
3684 set_user_nice(current
, nice
);
3691 * task_prio - return the priority value of a given task.
3692 * @p: the task in question.
3694 * This is the priority value as seen by users in /proc.
3695 * RT tasks are offset by -200. Normal tasks are centered
3696 * around 0, value goes from -16 to +15.
3698 int task_prio(const struct task_struct
*p
)
3700 return p
->prio
- MAX_RT_PRIO
;
3704 * task_nice - return the nice value of a given task.
3705 * @p: the task in question.
3707 int task_nice(const struct task_struct
*p
)
3709 return TASK_NICE(p
);
3711 EXPORT_SYMBOL(task_nice
);
3714 * idle_cpu - is a given cpu idle currently?
3715 * @cpu: the processor in question.
3717 int idle_cpu(int cpu
)
3719 struct rq
*rq
= cpu_rq(cpu
);
3721 if (rq
->curr
!= rq
->idle
)
3728 if (!llist_empty(&rq
->wake_list
))
3736 * idle_task - return the idle task for a given cpu.
3737 * @cpu: the processor in question.
3739 struct task_struct
*idle_task(int cpu
)
3741 return cpu_rq(cpu
)->idle
;
3745 * find_process_by_pid - find a process with a matching PID value.
3746 * @pid: the pid in question.
3748 static struct task_struct
*find_process_by_pid(pid_t pid
)
3750 return pid
? find_task_by_vpid(pid
) : current
;
3753 /* Actually do priority change: must hold rq lock. */
3755 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
3758 p
->rt_priority
= prio
;
3759 p
->normal_prio
= normal_prio(p
);
3760 /* we are holding p->pi_lock already */
3761 p
->prio
= rt_mutex_getprio(p
);
3762 if (rt_prio(p
->prio
))
3763 p
->sched_class
= &rt_sched_class
;
3765 p
->sched_class
= &fair_sched_class
;
3770 * check the target process has a UID that matches the current process's
3772 static bool check_same_owner(struct task_struct
*p
)
3774 const struct cred
*cred
= current_cred(), *pcred
;
3778 pcred
= __task_cred(p
);
3779 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3780 uid_eq(cred
->euid
, pcred
->uid
));
3785 static int __sched_setscheduler(struct task_struct
*p
, int policy
,
3786 const struct sched_param
*param
, bool user
)
3788 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
3789 unsigned long flags
;
3790 const struct sched_class
*prev_class
;
3794 /* may grab non-irq protected spin_locks */
3795 BUG_ON(in_interrupt());
3797 /* double check policy once rq lock held */
3799 reset_on_fork
= p
->sched_reset_on_fork
;
3800 policy
= oldpolicy
= p
->policy
;
3802 reset_on_fork
= !!(policy
& SCHED_RESET_ON_FORK
);
3803 policy
&= ~SCHED_RESET_ON_FORK
;
3805 if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3806 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
3807 policy
!= SCHED_IDLE
)
3812 * Valid priorities for SCHED_FIFO and SCHED_RR are
3813 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3814 * SCHED_BATCH and SCHED_IDLE is 0.
3816 if (param
->sched_priority
< 0 ||
3817 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3818 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3820 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
3824 * Allow unprivileged RT tasks to decrease priority:
3826 if (user
&& !capable(CAP_SYS_NICE
)) {
3827 if (rt_policy(policy
)) {
3828 unsigned long rlim_rtprio
=
3829 task_rlimit(p
, RLIMIT_RTPRIO
);
3831 /* can't set/change the rt policy */
3832 if (policy
!= p
->policy
&& !rlim_rtprio
)
3835 /* can't increase priority */
3836 if (param
->sched_priority
> p
->rt_priority
&&
3837 param
->sched_priority
> rlim_rtprio
)
3842 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3843 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3845 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
3846 if (!can_nice(p
, TASK_NICE(p
)))
3850 /* can't change other user's priorities */
3851 if (!check_same_owner(p
))
3854 /* Normal users shall not reset the sched_reset_on_fork flag */
3855 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3860 retval
= security_task_setscheduler(p
);
3866 * make sure no PI-waiters arrive (or leave) while we are
3867 * changing the priority of the task:
3869 * To be able to change p->policy safely, the appropriate
3870 * runqueue lock must be held.
3872 rq
= task_rq_lock(p
, &flags
);
3875 * Changing the policy of the stop threads its a very bad idea
3877 if (p
== rq
->stop
) {
3878 task_rq_unlock(rq
, p
, &flags
);
3883 * If not changing anything there's no need to proceed further:
3885 if (unlikely(policy
== p
->policy
&& (!rt_policy(policy
) ||
3886 param
->sched_priority
== p
->rt_priority
))) {
3887 task_rq_unlock(rq
, p
, &flags
);
3891 #ifdef CONFIG_RT_GROUP_SCHED
3894 * Do not allow realtime tasks into groups that have no runtime
3897 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
3898 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
3899 !task_group_is_autogroup(task_group(p
))) {
3900 task_rq_unlock(rq
, p
, &flags
);
3906 /* recheck policy now with rq lock held */
3907 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3908 policy
= oldpolicy
= -1;
3909 task_rq_unlock(rq
, p
, &flags
);
3913 running
= task_current(rq
, p
);
3915 dequeue_task(rq
, p
, 0);
3917 p
->sched_class
->put_prev_task(rq
, p
);
3919 p
->sched_reset_on_fork
= reset_on_fork
;
3922 prev_class
= p
->sched_class
;
3923 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
3926 p
->sched_class
->set_curr_task(rq
);
3928 enqueue_task(rq
, p
, 0);
3930 check_class_changed(rq
, p
, prev_class
, oldprio
);
3931 task_rq_unlock(rq
, p
, &flags
);
3933 rt_mutex_adjust_pi(p
);
3939 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3940 * @p: the task in question.
3941 * @policy: new policy.
3942 * @param: structure containing the new RT priority.
3944 * NOTE that the task may be already dead.
3946 int sched_setscheduler(struct task_struct
*p
, int policy
,
3947 const struct sched_param
*param
)
3949 return __sched_setscheduler(p
, policy
, param
, true);
3951 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3954 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3955 * @p: the task in question.
3956 * @policy: new policy.
3957 * @param: structure containing the new RT priority.
3959 * Just like sched_setscheduler, only don't bother checking if the
3960 * current context has permission. For example, this is needed in
3961 * stop_machine(): we create temporary high priority worker threads,
3962 * but our caller might not have that capability.
3964 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
3965 const struct sched_param
*param
)
3967 return __sched_setscheduler(p
, policy
, param
, false);
3971 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3973 struct sched_param lparam
;
3974 struct task_struct
*p
;
3977 if (!param
|| pid
< 0)
3979 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3984 p
= find_process_by_pid(pid
);
3986 retval
= sched_setscheduler(p
, policy
, &lparam
);
3993 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3994 * @pid: the pid in question.
3995 * @policy: new policy.
3996 * @param: structure containing the new RT priority.
3998 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
3999 struct sched_param __user
*, param
)
4001 /* negative values for policy are not valid */
4005 return do_sched_setscheduler(pid
, policy
, param
);
4009 * sys_sched_setparam - set/change the RT priority of a thread
4010 * @pid: the pid in question.
4011 * @param: structure containing the new RT priority.
4013 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4015 return do_sched_setscheduler(pid
, -1, param
);
4019 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4020 * @pid: the pid in question.
4022 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
4024 struct task_struct
*p
;
4032 p
= find_process_by_pid(pid
);
4034 retval
= security_task_getscheduler(p
);
4037 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
4044 * sys_sched_getparam - get the RT priority of a thread
4045 * @pid: the pid in question.
4046 * @param: structure containing the RT priority.
4048 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4050 struct sched_param lp
;
4051 struct task_struct
*p
;
4054 if (!param
|| pid
< 0)
4058 p
= find_process_by_pid(pid
);
4063 retval
= security_task_getscheduler(p
);
4067 lp
.sched_priority
= p
->rt_priority
;
4071 * This one might sleep, we cannot do it with a spinlock held ...
4073 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4082 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
4084 cpumask_var_t cpus_allowed
, new_mask
;
4085 struct task_struct
*p
;
4091 p
= find_process_by_pid(pid
);
4098 /* Prevent p going away */
4102 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4106 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4108 goto out_free_cpus_allowed
;
4111 if (!check_same_owner(p
)) {
4113 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4120 retval
= security_task_setscheduler(p
);
4124 cpuset_cpus_allowed(p
, cpus_allowed
);
4125 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4127 retval
= set_cpus_allowed_ptr(p
, new_mask
);
4130 cpuset_cpus_allowed(p
, cpus_allowed
);
4131 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4133 * We must have raced with a concurrent cpuset
4134 * update. Just reset the cpus_allowed to the
4135 * cpuset's cpus_allowed
4137 cpumask_copy(new_mask
, cpus_allowed
);
4142 free_cpumask_var(new_mask
);
4143 out_free_cpus_allowed
:
4144 free_cpumask_var(cpus_allowed
);
4151 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4152 struct cpumask
*new_mask
)
4154 if (len
< cpumask_size())
4155 cpumask_clear(new_mask
);
4156 else if (len
> cpumask_size())
4157 len
= cpumask_size();
4159 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4163 * sys_sched_setaffinity - set the cpu affinity of a process
4164 * @pid: pid of the process
4165 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4166 * @user_mask_ptr: user-space pointer to the new cpu mask
4168 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4169 unsigned long __user
*, user_mask_ptr
)
4171 cpumask_var_t new_mask
;
4174 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4177 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4179 retval
= sched_setaffinity(pid
, new_mask
);
4180 free_cpumask_var(new_mask
);
4184 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4186 struct task_struct
*p
;
4187 unsigned long flags
;
4194 p
= find_process_by_pid(pid
);
4198 retval
= security_task_getscheduler(p
);
4202 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4203 cpumask_and(mask
, &p
->cpus_allowed
, cpu_online_mask
);
4204 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4214 * sys_sched_getaffinity - get the cpu affinity of a process
4215 * @pid: pid of the process
4216 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4217 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4219 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4220 unsigned long __user
*, user_mask_ptr
)
4225 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4227 if (len
& (sizeof(unsigned long)-1))
4230 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4233 ret
= sched_getaffinity(pid
, mask
);
4235 size_t retlen
= min_t(size_t, len
, cpumask_size());
4237 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4242 free_cpumask_var(mask
);
4248 * sys_sched_yield - yield the current processor to other threads.
4250 * This function yields the current CPU to other tasks. If there are no
4251 * other threads running on this CPU then this function will return.
4253 SYSCALL_DEFINE0(sched_yield
)
4255 struct rq
*rq
= this_rq_lock();
4257 schedstat_inc(rq
, yld_count
);
4258 current
->sched_class
->yield_task(rq
);
4261 * Since we are going to call schedule() anyway, there's
4262 * no need to preempt or enable interrupts:
4264 __release(rq
->lock
);
4265 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4266 do_raw_spin_unlock(&rq
->lock
);
4267 sched_preempt_enable_no_resched();
4274 static inline int should_resched(void)
4276 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE
);
4279 static void __cond_resched(void)
4281 add_preempt_count(PREEMPT_ACTIVE
);
4283 sub_preempt_count(PREEMPT_ACTIVE
);
4286 int __sched
_cond_resched(void)
4288 if (should_resched()) {
4294 EXPORT_SYMBOL(_cond_resched
);
4297 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4298 * call schedule, and on return reacquire the lock.
4300 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4301 * operations here to prevent schedule() from being called twice (once via
4302 * spin_unlock(), once by hand).
4304 int __cond_resched_lock(spinlock_t
*lock
)
4306 int resched
= should_resched();
4309 lockdep_assert_held(lock
);
4311 if (spin_needbreak(lock
) || resched
) {
4322 EXPORT_SYMBOL(__cond_resched_lock
);
4324 int __sched
__cond_resched_softirq(void)
4326 BUG_ON(!in_softirq());
4328 if (should_resched()) {
4336 EXPORT_SYMBOL(__cond_resched_softirq
);
4339 * yield - yield the current processor to other threads.
4341 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4343 * The scheduler is at all times free to pick the calling task as the most
4344 * eligible task to run, if removing the yield() call from your code breaks
4345 * it, its already broken.
4347 * Typical broken usage is:
4352 * where one assumes that yield() will let 'the other' process run that will
4353 * make event true. If the current task is a SCHED_FIFO task that will never
4354 * happen. Never use yield() as a progress guarantee!!
4356 * If you want to use yield() to wait for something, use wait_event().
4357 * If you want to use yield() to be 'nice' for others, use cond_resched().
4358 * If you still want to use yield(), do not!
4360 void __sched
yield(void)
4362 set_current_state(TASK_RUNNING
);
4365 EXPORT_SYMBOL(yield
);
4368 * yield_to - yield the current processor to another thread in
4369 * your thread group, or accelerate that thread toward the
4370 * processor it's on.
4372 * @preempt: whether task preemption is allowed or not
4374 * It's the caller's job to ensure that the target task struct
4375 * can't go away on us before we can do any checks.
4378 * true (>0) if we indeed boosted the target task.
4379 * false (0) if we failed to boost the target.
4380 * -ESRCH if there's no task to yield to.
4382 bool __sched
yield_to(struct task_struct
*p
, bool preempt
)
4384 struct task_struct
*curr
= current
;
4385 struct rq
*rq
, *p_rq
;
4386 unsigned long flags
;
4389 local_irq_save(flags
);
4395 * If we're the only runnable task on the rq and target rq also
4396 * has only one task, there's absolutely no point in yielding.
4398 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4403 double_rq_lock(rq
, p_rq
);
4404 while (task_rq(p
) != p_rq
) {
4405 double_rq_unlock(rq
, p_rq
);
4409 if (!curr
->sched_class
->yield_to_task
)
4412 if (curr
->sched_class
!= p
->sched_class
)
4415 if (task_running(p_rq
, p
) || p
->state
)
4418 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4420 schedstat_inc(rq
, yld_count
);
4422 * Make p's CPU reschedule; pick_next_entity takes care of
4425 if (preempt
&& rq
!= p_rq
)
4426 resched_task(p_rq
->curr
);
4430 double_rq_unlock(rq
, p_rq
);
4432 local_irq_restore(flags
);
4439 EXPORT_SYMBOL_GPL(yield_to
);
4442 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4443 * that process accounting knows that this is a task in IO wait state.
4445 void __sched
io_schedule(void)
4447 struct rq
*rq
= raw_rq();
4449 delayacct_blkio_start();
4450 atomic_inc(&rq
->nr_iowait
);
4451 blk_flush_plug(current
);
4452 current
->in_iowait
= 1;
4454 current
->in_iowait
= 0;
4455 atomic_dec(&rq
->nr_iowait
);
4456 delayacct_blkio_end();
4458 EXPORT_SYMBOL(io_schedule
);
4460 long __sched
io_schedule_timeout(long timeout
)
4462 struct rq
*rq
= raw_rq();
4465 delayacct_blkio_start();
4466 atomic_inc(&rq
->nr_iowait
);
4467 blk_flush_plug(current
);
4468 current
->in_iowait
= 1;
4469 ret
= schedule_timeout(timeout
);
4470 current
->in_iowait
= 0;
4471 atomic_dec(&rq
->nr_iowait
);
4472 delayacct_blkio_end();
4477 * sys_sched_get_priority_max - return maximum RT priority.
4478 * @policy: scheduling class.
4480 * this syscall returns the maximum rt_priority that can be used
4481 * by a given scheduling class.
4483 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
4490 ret
= MAX_USER_RT_PRIO
-1;
4502 * sys_sched_get_priority_min - return minimum RT priority.
4503 * @policy: scheduling class.
4505 * this syscall returns the minimum rt_priority that can be used
4506 * by a given scheduling class.
4508 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
4526 * sys_sched_rr_get_interval - return the default timeslice of a process.
4527 * @pid: pid of the process.
4528 * @interval: userspace pointer to the timeslice value.
4530 * this syscall writes the default timeslice value of a given process
4531 * into the user-space timespec buffer. A value of '0' means infinity.
4533 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
4534 struct timespec __user
*, interval
)
4536 struct task_struct
*p
;
4537 unsigned int time_slice
;
4538 unsigned long flags
;
4548 p
= find_process_by_pid(pid
);
4552 retval
= security_task_getscheduler(p
);
4556 rq
= task_rq_lock(p
, &flags
);
4557 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
4558 task_rq_unlock(rq
, p
, &flags
);
4561 jiffies_to_timespec(time_slice
, &t
);
4562 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4570 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
4572 void sched_show_task(struct task_struct
*p
)
4574 unsigned long free
= 0;
4578 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4579 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
4580 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4581 #if BITS_PER_LONG == 32
4582 if (state
== TASK_RUNNING
)
4583 printk(KERN_CONT
" running ");
4585 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4587 if (state
== TASK_RUNNING
)
4588 printk(KERN_CONT
" running task ");
4590 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4592 #ifdef CONFIG_DEBUG_STACK_USAGE
4593 free
= stack_not_used(p
);
4596 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
4598 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
4599 task_pid_nr(p
), ppid
,
4600 (unsigned long)task_thread_info(p
)->flags
);
4602 show_stack(p
, NULL
);
4605 void show_state_filter(unsigned long state_filter
)
4607 struct task_struct
*g
, *p
;
4609 #if BITS_PER_LONG == 32
4611 " task PC stack pid father\n");
4614 " task PC stack pid father\n");
4617 do_each_thread(g
, p
) {
4619 * reset the NMI-timeout, listing all files on a slow
4620 * console might take a lot of time:
4622 touch_nmi_watchdog();
4623 if (!state_filter
|| (p
->state
& state_filter
))
4625 } while_each_thread(g
, p
);
4627 touch_all_softlockup_watchdogs();
4629 #ifdef CONFIG_SCHED_DEBUG
4630 sysrq_sched_debug_show();
4634 * Only show locks if all tasks are dumped:
4637 debug_show_all_locks();
4640 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4642 idle
->sched_class
= &idle_sched_class
;
4646 * init_idle - set up an idle thread for a given CPU
4647 * @idle: task in question
4648 * @cpu: cpu the idle task belongs to
4650 * NOTE: this function does not set the idle thread's NEED_RESCHED
4651 * flag, to make booting more robust.
4653 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4655 struct rq
*rq
= cpu_rq(cpu
);
4656 unsigned long flags
;
4658 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4661 idle
->state
= TASK_RUNNING
;
4662 idle
->se
.exec_start
= sched_clock();
4664 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
4666 * We're having a chicken and egg problem, even though we are
4667 * holding rq->lock, the cpu isn't yet set to this cpu so the
4668 * lockdep check in task_group() will fail.
4670 * Similar case to sched_fork(). / Alternatively we could
4671 * use task_rq_lock() here and obtain the other rq->lock.
4676 __set_task_cpu(idle
, cpu
);
4679 rq
->curr
= rq
->idle
= idle
;
4680 #if defined(CONFIG_SMP)
4683 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4685 /* Set the preempt count _outside_ the spinlocks! */
4686 task_thread_info(idle
)->preempt_count
= 0;
4689 * The idle tasks have their own, simple scheduling class:
4691 idle
->sched_class
= &idle_sched_class
;
4692 ftrace_graph_init_idle_task(idle
, cpu
);
4693 vtime_init_idle(idle
);
4694 #if defined(CONFIG_SMP)
4695 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
4700 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
4702 if (p
->sched_class
&& p
->sched_class
->set_cpus_allowed
)
4703 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
4705 cpumask_copy(&p
->cpus_allowed
, new_mask
);
4706 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
4710 * This is how migration works:
4712 * 1) we invoke migration_cpu_stop() on the target CPU using
4714 * 2) stopper starts to run (implicitly forcing the migrated thread
4716 * 3) it checks whether the migrated task is still in the wrong runqueue.
4717 * 4) if it's in the wrong runqueue then the migration thread removes
4718 * it and puts it into the right queue.
4719 * 5) stopper completes and stop_one_cpu() returns and the migration
4724 * Change a given task's CPU affinity. Migrate the thread to a
4725 * proper CPU and schedule it away if the CPU it's executing on
4726 * is removed from the allowed bitmask.
4728 * NOTE: the caller must have a valid reference to the task, the
4729 * task must not exit() & deallocate itself prematurely. The
4730 * call is not atomic; no spinlocks may be held.
4732 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
4734 unsigned long flags
;
4736 unsigned int dest_cpu
;
4739 rq
= task_rq_lock(p
, &flags
);
4741 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
4744 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
4749 if (unlikely((p
->flags
& PF_THREAD_BOUND
) && p
!= current
)) {
4754 do_set_cpus_allowed(p
, new_mask
);
4756 /* Can the task run on the task's current CPU? If so, we're done */
4757 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
4760 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
4762 struct migration_arg arg
= { p
, dest_cpu
};
4763 /* Need help from migration thread: drop lock and wait. */
4764 task_rq_unlock(rq
, p
, &flags
);
4765 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
4766 tlb_migrate_finish(p
->mm
);
4770 task_rq_unlock(rq
, p
, &flags
);
4774 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
4777 * Move (not current) task off this cpu, onto dest cpu. We're doing
4778 * this because either it can't run here any more (set_cpus_allowed()
4779 * away from this CPU, or CPU going down), or because we're
4780 * attempting to rebalance this task on exec (sched_exec).
4782 * So we race with normal scheduler movements, but that's OK, as long
4783 * as the task is no longer on this CPU.
4785 * Returns non-zero if task was successfully migrated.
4787 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4789 struct rq
*rq_dest
, *rq_src
;
4792 if (unlikely(!cpu_active(dest_cpu
)))
4795 rq_src
= cpu_rq(src_cpu
);
4796 rq_dest
= cpu_rq(dest_cpu
);
4798 raw_spin_lock(&p
->pi_lock
);
4799 double_rq_lock(rq_src
, rq_dest
);
4800 /* Already moved. */
4801 if (task_cpu(p
) != src_cpu
)
4803 /* Affinity changed (again). */
4804 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
4808 * If we're not on a rq, the next wake-up will ensure we're
4812 dequeue_task(rq_src
, p
, 0);
4813 set_task_cpu(p
, dest_cpu
);
4814 enqueue_task(rq_dest
, p
, 0);
4815 check_preempt_curr(rq_dest
, p
, 0);
4820 double_rq_unlock(rq_src
, rq_dest
);
4821 raw_spin_unlock(&p
->pi_lock
);
4826 * migration_cpu_stop - this will be executed by a highprio stopper thread
4827 * and performs thread migration by bumping thread off CPU then
4828 * 'pushing' onto another runqueue.
4830 static int migration_cpu_stop(void *data
)
4832 struct migration_arg
*arg
= data
;
4835 * The original target cpu might have gone down and we might
4836 * be on another cpu but it doesn't matter.
4838 local_irq_disable();
4839 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
4844 #ifdef CONFIG_HOTPLUG_CPU
4847 * Ensures that the idle task is using init_mm right before its cpu goes
4850 void idle_task_exit(void)
4852 struct mm_struct
*mm
= current
->active_mm
;
4854 BUG_ON(cpu_online(smp_processor_id()));
4857 switch_mm(mm
, &init_mm
, current
);
4862 * Since this CPU is going 'away' for a while, fold any nr_active delta
4863 * we might have. Assumes we're called after migrate_tasks() so that the
4864 * nr_active count is stable.
4866 * Also see the comment "Global load-average calculations".
4868 static void calc_load_migrate(struct rq
*rq
)
4870 long delta
= calc_load_fold_active(rq
);
4872 atomic_long_add(delta
, &calc_load_tasks
);
4876 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4877 * try_to_wake_up()->select_task_rq().
4879 * Called with rq->lock held even though we'er in stop_machine() and
4880 * there's no concurrency possible, we hold the required locks anyway
4881 * because of lock validation efforts.
4883 static void migrate_tasks(unsigned int dead_cpu
)
4885 struct rq
*rq
= cpu_rq(dead_cpu
);
4886 struct task_struct
*next
, *stop
= rq
->stop
;
4890 * Fudge the rq selection such that the below task selection loop
4891 * doesn't get stuck on the currently eligible stop task.
4893 * We're currently inside stop_machine() and the rq is either stuck
4894 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4895 * either way we should never end up calling schedule() until we're
4902 * There's this thread running, bail when that's the only
4905 if (rq
->nr_running
== 1)
4908 next
= pick_next_task(rq
);
4910 next
->sched_class
->put_prev_task(rq
, next
);
4912 /* Find suitable destination for @next, with force if needed. */
4913 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
4914 raw_spin_unlock(&rq
->lock
);
4916 __migrate_task(next
, dead_cpu
, dest_cpu
);
4918 raw_spin_lock(&rq
->lock
);
4924 #endif /* CONFIG_HOTPLUG_CPU */
4926 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4928 static struct ctl_table sd_ctl_dir
[] = {
4930 .procname
= "sched_domain",
4936 static struct ctl_table sd_ctl_root
[] = {
4938 .procname
= "kernel",
4940 .child
= sd_ctl_dir
,
4945 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
4947 struct ctl_table
*entry
=
4948 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
4953 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
4955 struct ctl_table
*entry
;
4958 * In the intermediate directories, both the child directory and
4959 * procname are dynamically allocated and could fail but the mode
4960 * will always be set. In the lowest directory the names are
4961 * static strings and all have proc handlers.
4963 for (entry
= *tablep
; entry
->mode
; entry
++) {
4965 sd_free_ctl_entry(&entry
->child
);
4966 if (entry
->proc_handler
== NULL
)
4967 kfree(entry
->procname
);
4974 static int min_load_idx
= 0;
4975 static int max_load_idx
= CPU_LOAD_IDX_MAX
;
4978 set_table_entry(struct ctl_table
*entry
,
4979 const char *procname
, void *data
, int maxlen
,
4980 umode_t mode
, proc_handler
*proc_handler
,
4983 entry
->procname
= procname
;
4985 entry
->maxlen
= maxlen
;
4987 entry
->proc_handler
= proc_handler
;
4990 entry
->extra1
= &min_load_idx
;
4991 entry
->extra2
= &max_load_idx
;
4995 static struct ctl_table
*
4996 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
4998 struct ctl_table
*table
= sd_alloc_ctl_entry(13);
5003 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5004 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5005 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5006 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5007 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5008 sizeof(int), 0644, proc_dointvec_minmax
, true);
5009 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5010 sizeof(int), 0644, proc_dointvec_minmax
, true);
5011 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5012 sizeof(int), 0644, proc_dointvec_minmax
, true);
5013 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5014 sizeof(int), 0644, proc_dointvec_minmax
, true);
5015 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5016 sizeof(int), 0644, proc_dointvec_minmax
, true);
5017 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5018 sizeof(int), 0644, proc_dointvec_minmax
, false);
5019 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5020 sizeof(int), 0644, proc_dointvec_minmax
, false);
5021 set_table_entry(&table
[9], "cache_nice_tries",
5022 &sd
->cache_nice_tries
,
5023 sizeof(int), 0644, proc_dointvec_minmax
, false);
5024 set_table_entry(&table
[10], "flags", &sd
->flags
,
5025 sizeof(int), 0644, proc_dointvec_minmax
, false);
5026 set_table_entry(&table
[11], "name", sd
->name
,
5027 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
5028 /* &table[12] is terminator */
5033 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5035 struct ctl_table
*entry
, *table
;
5036 struct sched_domain
*sd
;
5037 int domain_num
= 0, i
;
5040 for_each_domain(cpu
, sd
)
5042 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5047 for_each_domain(cpu
, sd
) {
5048 snprintf(buf
, 32, "domain%d", i
);
5049 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5051 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5058 static struct ctl_table_header
*sd_sysctl_header
;
5059 static void register_sched_domain_sysctl(void)
5061 int i
, cpu_num
= num_possible_cpus();
5062 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5065 WARN_ON(sd_ctl_dir
[0].child
);
5066 sd_ctl_dir
[0].child
= entry
;
5071 for_each_possible_cpu(i
) {
5072 snprintf(buf
, 32, "cpu%d", i
);
5073 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5075 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5079 WARN_ON(sd_sysctl_header
);
5080 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5083 /* may be called multiple times per register */
5084 static void unregister_sched_domain_sysctl(void)
5086 if (sd_sysctl_header
)
5087 unregister_sysctl_table(sd_sysctl_header
);
5088 sd_sysctl_header
= NULL
;
5089 if (sd_ctl_dir
[0].child
)
5090 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5093 static void register_sched_domain_sysctl(void)
5096 static void unregister_sched_domain_sysctl(void)
5101 static void set_rq_online(struct rq
*rq
)
5104 const struct sched_class
*class;
5106 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5109 for_each_class(class) {
5110 if (class->rq_online
)
5111 class->rq_online(rq
);
5116 static void set_rq_offline(struct rq
*rq
)
5119 const struct sched_class
*class;
5121 for_each_class(class) {
5122 if (class->rq_offline
)
5123 class->rq_offline(rq
);
5126 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5132 * migration_call - callback that gets triggered when a CPU is added.
5133 * Here we can start up the necessary migration thread for the new CPU.
5135 static int __cpuinit
5136 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5138 int cpu
= (long)hcpu
;
5139 unsigned long flags
;
5140 struct rq
*rq
= cpu_rq(cpu
);
5142 switch (action
& ~CPU_TASKS_FROZEN
) {
5144 case CPU_UP_PREPARE
:
5145 rq
->calc_load_update
= calc_load_update
;
5149 /* Update our root-domain */
5150 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5152 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5156 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5159 #ifdef CONFIG_HOTPLUG_CPU
5161 sched_ttwu_pending();
5162 /* Update our root-domain */
5163 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5165 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5169 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
5170 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5174 calc_load_migrate(rq
);
5179 update_max_interval();
5185 * Register at high priority so that task migration (migrate_all_tasks)
5186 * happens before everything else. This has to be lower priority than
5187 * the notifier in the perf_event subsystem, though.
5189 static struct notifier_block __cpuinitdata migration_notifier
= {
5190 .notifier_call
= migration_call
,
5191 .priority
= CPU_PRI_MIGRATION
,
5194 static int __cpuinit
sched_cpu_active(struct notifier_block
*nfb
,
5195 unsigned long action
, void *hcpu
)
5197 switch (action
& ~CPU_TASKS_FROZEN
) {
5199 case CPU_DOWN_FAILED
:
5200 set_cpu_active((long)hcpu
, true);
5207 static int __cpuinit
sched_cpu_inactive(struct notifier_block
*nfb
,
5208 unsigned long action
, void *hcpu
)
5210 switch (action
& ~CPU_TASKS_FROZEN
) {
5211 case CPU_DOWN_PREPARE
:
5212 set_cpu_active((long)hcpu
, false);
5219 static int __init
migration_init(void)
5221 void *cpu
= (void *)(long)smp_processor_id();
5224 /* Initialize migration for the boot CPU */
5225 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5226 BUG_ON(err
== NOTIFY_BAD
);
5227 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5228 register_cpu_notifier(&migration_notifier
);
5230 /* Register cpu active notifiers */
5231 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
5232 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
5236 early_initcall(migration_init
);
5241 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5243 #ifdef CONFIG_SCHED_DEBUG
5245 static __read_mostly
int sched_debug_enabled
;
5247 static int __init
sched_debug_setup(char *str
)
5249 sched_debug_enabled
= 1;
5253 early_param("sched_debug", sched_debug_setup
);
5255 static inline bool sched_debug(void)
5257 return sched_debug_enabled
;
5260 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5261 struct cpumask
*groupmask
)
5263 struct sched_group
*group
= sd
->groups
;
5266 cpulist_scnprintf(str
, sizeof(str
), sched_domain_span(sd
));
5267 cpumask_clear(groupmask
);
5269 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5271 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5272 printk("does not load-balance\n");
5274 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5279 printk(KERN_CONT
"span %s level %s\n", str
, sd
->name
);
5281 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5282 printk(KERN_ERR
"ERROR: domain->span does not contain "
5285 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5286 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5290 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5294 printk(KERN_ERR
"ERROR: group is NULL\n");
5299 * Even though we initialize ->power to something semi-sane,
5300 * we leave power_orig unset. This allows us to detect if
5301 * domain iteration is still funny without causing /0 traps.
5303 if (!group
->sgp
->power_orig
) {
5304 printk(KERN_CONT
"\n");
5305 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5310 if (!cpumask_weight(sched_group_cpus(group
))) {
5311 printk(KERN_CONT
"\n");
5312 printk(KERN_ERR
"ERROR: empty group\n");
5316 if (!(sd
->flags
& SD_OVERLAP
) &&
5317 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5318 printk(KERN_CONT
"\n");
5319 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5323 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5325 cpulist_scnprintf(str
, sizeof(str
), sched_group_cpus(group
));
5327 printk(KERN_CONT
" %s", str
);
5328 if (group
->sgp
->power
!= SCHED_POWER_SCALE
) {
5329 printk(KERN_CONT
" (cpu_power = %d)",
5333 group
= group
->next
;
5334 } while (group
!= sd
->groups
);
5335 printk(KERN_CONT
"\n");
5337 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5338 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5341 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5342 printk(KERN_ERR
"ERROR: parent span is not a superset "
5343 "of domain->span\n");
5347 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5351 if (!sched_debug_enabled
)
5355 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5359 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5362 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5370 #else /* !CONFIG_SCHED_DEBUG */
5371 # define sched_domain_debug(sd, cpu) do { } while (0)
5372 static inline bool sched_debug(void)
5376 #endif /* CONFIG_SCHED_DEBUG */
5378 static int sd_degenerate(struct sched_domain
*sd
)
5380 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5383 /* Following flags need at least 2 groups */
5384 if (sd
->flags
& (SD_LOAD_BALANCE
|
5385 SD_BALANCE_NEWIDLE
|
5389 SD_SHARE_PKG_RESOURCES
)) {
5390 if (sd
->groups
!= sd
->groups
->next
)
5394 /* Following flags don't use groups */
5395 if (sd
->flags
& (SD_WAKE_AFFINE
))
5402 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5404 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5406 if (sd_degenerate(parent
))
5409 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5412 /* Flags needing groups don't count if only 1 group in parent */
5413 if (parent
->groups
== parent
->groups
->next
) {
5414 pflags
&= ~(SD_LOAD_BALANCE
|
5415 SD_BALANCE_NEWIDLE
|
5419 SD_SHARE_PKG_RESOURCES
);
5420 if (nr_node_ids
== 1)
5421 pflags
&= ~SD_SERIALIZE
;
5423 if (~cflags
& pflags
)
5429 static void free_rootdomain(struct rcu_head
*rcu
)
5431 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5433 cpupri_cleanup(&rd
->cpupri
);
5434 free_cpumask_var(rd
->rto_mask
);
5435 free_cpumask_var(rd
->online
);
5436 free_cpumask_var(rd
->span
);
5440 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5442 struct root_domain
*old_rd
= NULL
;
5443 unsigned long flags
;
5445 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5450 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5453 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5456 * If we dont want to free the old_rt yet then
5457 * set old_rd to NULL to skip the freeing later
5460 if (!atomic_dec_and_test(&old_rd
->refcount
))
5464 atomic_inc(&rd
->refcount
);
5467 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5468 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5471 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5474 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5477 static int init_rootdomain(struct root_domain
*rd
)
5479 memset(rd
, 0, sizeof(*rd
));
5481 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5483 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5485 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5488 if (cpupri_init(&rd
->cpupri
) != 0)
5493 free_cpumask_var(rd
->rto_mask
);
5495 free_cpumask_var(rd
->online
);
5497 free_cpumask_var(rd
->span
);
5503 * By default the system creates a single root-domain with all cpus as
5504 * members (mimicking the global state we have today).
5506 struct root_domain def_root_domain
;
5508 static void init_defrootdomain(void)
5510 init_rootdomain(&def_root_domain
);
5512 atomic_set(&def_root_domain
.refcount
, 1);
5515 static struct root_domain
*alloc_rootdomain(void)
5517 struct root_domain
*rd
;
5519 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
5523 if (init_rootdomain(rd
) != 0) {
5531 static void free_sched_groups(struct sched_group
*sg
, int free_sgp
)
5533 struct sched_group
*tmp
, *first
;
5542 if (free_sgp
&& atomic_dec_and_test(&sg
->sgp
->ref
))
5547 } while (sg
!= first
);
5550 static void free_sched_domain(struct rcu_head
*rcu
)
5552 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
5555 * If its an overlapping domain it has private groups, iterate and
5558 if (sd
->flags
& SD_OVERLAP
) {
5559 free_sched_groups(sd
->groups
, 1);
5560 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
5561 kfree(sd
->groups
->sgp
);
5567 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
5569 call_rcu(&sd
->rcu
, free_sched_domain
);
5572 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
5574 for (; sd
; sd
= sd
->parent
)
5575 destroy_sched_domain(sd
, cpu
);
5579 * Keep a special pointer to the highest sched_domain that has
5580 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5581 * allows us to avoid some pointer chasing select_idle_sibling().
5583 * Also keep a unique ID per domain (we use the first cpu number in
5584 * the cpumask of the domain), this allows us to quickly tell if
5585 * two cpus are in the same cache domain, see cpus_share_cache().
5587 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
5588 DEFINE_PER_CPU(int, sd_llc_id
);
5590 static void update_top_cache_domain(int cpu
)
5592 struct sched_domain
*sd
;
5595 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
5597 id
= cpumask_first(sched_domain_span(sd
));
5599 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
5600 per_cpu(sd_llc_id
, cpu
) = id
;
5604 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5605 * hold the hotplug lock.
5608 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
5610 struct rq
*rq
= cpu_rq(cpu
);
5611 struct sched_domain
*tmp
;
5613 /* Remove the sched domains which do not contribute to scheduling. */
5614 for (tmp
= sd
; tmp
; ) {
5615 struct sched_domain
*parent
= tmp
->parent
;
5619 if (sd_parent_degenerate(tmp
, parent
)) {
5620 tmp
->parent
= parent
->parent
;
5622 parent
->parent
->child
= tmp
;
5623 destroy_sched_domain(parent
, cpu
);
5628 if (sd
&& sd_degenerate(sd
)) {
5631 destroy_sched_domain(tmp
, cpu
);
5636 sched_domain_debug(sd
, cpu
);
5638 rq_attach_root(rq
, rd
);
5640 rcu_assign_pointer(rq
->sd
, sd
);
5641 destroy_sched_domains(tmp
, cpu
);
5643 update_top_cache_domain(cpu
);
5646 /* cpus with isolated domains */
5647 static cpumask_var_t cpu_isolated_map
;
5649 /* Setup the mask of cpus configured for isolated domains */
5650 static int __init
isolated_cpu_setup(char *str
)
5652 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
5653 cpulist_parse(str
, cpu_isolated_map
);
5657 __setup("isolcpus=", isolated_cpu_setup
);
5659 static const struct cpumask
*cpu_cpu_mask(int cpu
)
5661 return cpumask_of_node(cpu_to_node(cpu
));
5665 struct sched_domain
**__percpu sd
;
5666 struct sched_group
**__percpu sg
;
5667 struct sched_group_power
**__percpu sgp
;
5671 struct sched_domain
** __percpu sd
;
5672 struct root_domain
*rd
;
5682 struct sched_domain_topology_level
;
5684 typedef struct sched_domain
*(*sched_domain_init_f
)(struct sched_domain_topology_level
*tl
, int cpu
);
5685 typedef const struct cpumask
*(*sched_domain_mask_f
)(int cpu
);
5687 #define SDTL_OVERLAP 0x01
5689 struct sched_domain_topology_level
{
5690 sched_domain_init_f init
;
5691 sched_domain_mask_f mask
;
5694 struct sd_data data
;
5698 * Build an iteration mask that can exclude certain CPUs from the upwards
5701 * Asymmetric node setups can result in situations where the domain tree is of
5702 * unequal depth, make sure to skip domains that already cover the entire
5705 * In that case build_sched_domains() will have terminated the iteration early
5706 * and our sibling sd spans will be empty. Domains should always include the
5707 * cpu they're built on, so check that.
5710 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
5712 const struct cpumask
*span
= sched_domain_span(sd
);
5713 struct sd_data
*sdd
= sd
->private;
5714 struct sched_domain
*sibling
;
5717 for_each_cpu(i
, span
) {
5718 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5719 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5722 cpumask_set_cpu(i
, sched_group_mask(sg
));
5727 * Return the canonical balance cpu for this group, this is the first cpu
5728 * of this group that's also in the iteration mask.
5730 int group_balance_cpu(struct sched_group
*sg
)
5732 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
5736 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
5738 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
5739 const struct cpumask
*span
= sched_domain_span(sd
);
5740 struct cpumask
*covered
= sched_domains_tmpmask
;
5741 struct sd_data
*sdd
= sd
->private;
5742 struct sched_domain
*child
;
5745 cpumask_clear(covered
);
5747 for_each_cpu(i
, span
) {
5748 struct cpumask
*sg_span
;
5750 if (cpumask_test_cpu(i
, covered
))
5753 child
= *per_cpu_ptr(sdd
->sd
, i
);
5755 /* See the comment near build_group_mask(). */
5756 if (!cpumask_test_cpu(i
, sched_domain_span(child
)))
5759 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5760 GFP_KERNEL
, cpu_to_node(cpu
));
5765 sg_span
= sched_group_cpus(sg
);
5767 child
= child
->child
;
5768 cpumask_copy(sg_span
, sched_domain_span(child
));
5770 cpumask_set_cpu(i
, sg_span
);
5772 cpumask_or(covered
, covered
, sg_span
);
5774 sg
->sgp
= *per_cpu_ptr(sdd
->sgp
, i
);
5775 if (atomic_inc_return(&sg
->sgp
->ref
) == 1)
5776 build_group_mask(sd
, sg
);
5779 * Initialize sgp->power such that even if we mess up the
5780 * domains and no possible iteration will get us here, we won't
5783 sg
->sgp
->power
= SCHED_POWER_SCALE
* cpumask_weight(sg_span
);
5786 * Make sure the first group of this domain contains the
5787 * canonical balance cpu. Otherwise the sched_domain iteration
5788 * breaks. See update_sg_lb_stats().
5790 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
5791 group_balance_cpu(sg
) == cpu
)
5801 sd
->groups
= groups
;
5806 free_sched_groups(first
, 0);
5811 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
5813 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
5814 struct sched_domain
*child
= sd
->child
;
5817 cpu
= cpumask_first(sched_domain_span(child
));
5820 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
5821 (*sg
)->sgp
= *per_cpu_ptr(sdd
->sgp
, cpu
);
5822 atomic_set(&(*sg
)->sgp
->ref
, 1); /* for claim_allocations */
5829 * build_sched_groups will build a circular linked list of the groups
5830 * covered by the given span, and will set each group's ->cpumask correctly,
5831 * and ->cpu_power to 0.
5833 * Assumes the sched_domain tree is fully constructed
5836 build_sched_groups(struct sched_domain
*sd
, int cpu
)
5838 struct sched_group
*first
= NULL
, *last
= NULL
;
5839 struct sd_data
*sdd
= sd
->private;
5840 const struct cpumask
*span
= sched_domain_span(sd
);
5841 struct cpumask
*covered
;
5844 get_group(cpu
, sdd
, &sd
->groups
);
5845 atomic_inc(&sd
->groups
->ref
);
5847 if (cpu
!= cpumask_first(sched_domain_span(sd
)))
5850 lockdep_assert_held(&sched_domains_mutex
);
5851 covered
= sched_domains_tmpmask
;
5853 cpumask_clear(covered
);
5855 for_each_cpu(i
, span
) {
5856 struct sched_group
*sg
;
5857 int group
= get_group(i
, sdd
, &sg
);
5860 if (cpumask_test_cpu(i
, covered
))
5863 cpumask_clear(sched_group_cpus(sg
));
5865 cpumask_setall(sched_group_mask(sg
));
5867 for_each_cpu(j
, span
) {
5868 if (get_group(j
, sdd
, NULL
) != group
)
5871 cpumask_set_cpu(j
, covered
);
5872 cpumask_set_cpu(j
, sched_group_cpus(sg
));
5887 * Initialize sched groups cpu_power.
5889 * cpu_power indicates the capacity of sched group, which is used while
5890 * distributing the load between different sched groups in a sched domain.
5891 * Typically cpu_power for all the groups in a sched domain will be same unless
5892 * there are asymmetries in the topology. If there are asymmetries, group
5893 * having more cpu_power will pickup more load compared to the group having
5896 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5898 struct sched_group
*sg
= sd
->groups
;
5900 WARN_ON(!sd
|| !sg
);
5903 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
5905 } while (sg
!= sd
->groups
);
5907 if (cpu
!= group_balance_cpu(sg
))
5910 update_group_power(sd
, cpu
);
5911 atomic_set(&sg
->sgp
->nr_busy_cpus
, sg
->group_weight
);
5914 int __weak
arch_sd_sibling_asym_packing(void)
5916 return 0*SD_ASYM_PACKING
;
5920 * Initializers for schedule domains
5921 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5924 #ifdef CONFIG_SCHED_DEBUG
5925 # define SD_INIT_NAME(sd, type) sd->name = #type
5927 # define SD_INIT_NAME(sd, type) do { } while (0)
5930 #define SD_INIT_FUNC(type) \
5931 static noinline struct sched_domain * \
5932 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5934 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5935 *sd = SD_##type##_INIT; \
5936 SD_INIT_NAME(sd, type); \
5937 sd->private = &tl->data; \
5942 #ifdef CONFIG_SCHED_SMT
5943 SD_INIT_FUNC(SIBLING
)
5945 #ifdef CONFIG_SCHED_MC
5948 #ifdef CONFIG_SCHED_BOOK
5952 static int default_relax_domain_level
= -1;
5953 int sched_domain_level_max
;
5955 static int __init
setup_relax_domain_level(char *str
)
5957 if (kstrtoint(str
, 0, &default_relax_domain_level
))
5958 pr_warn("Unable to set relax_domain_level\n");
5962 __setup("relax_domain_level=", setup_relax_domain_level
);
5964 static void set_domain_attribute(struct sched_domain
*sd
,
5965 struct sched_domain_attr
*attr
)
5969 if (!attr
|| attr
->relax_domain_level
< 0) {
5970 if (default_relax_domain_level
< 0)
5973 request
= default_relax_domain_level
;
5975 request
= attr
->relax_domain_level
;
5976 if (request
< sd
->level
) {
5977 /* turn off idle balance on this domain */
5978 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5980 /* turn on idle balance on this domain */
5981 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5985 static void __sdt_free(const struct cpumask
*cpu_map
);
5986 static int __sdt_alloc(const struct cpumask
*cpu_map
);
5988 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
5989 const struct cpumask
*cpu_map
)
5993 if (!atomic_read(&d
->rd
->refcount
))
5994 free_rootdomain(&d
->rd
->rcu
); /* fall through */
5996 free_percpu(d
->sd
); /* fall through */
5998 __sdt_free(cpu_map
); /* fall through */
6004 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
6005 const struct cpumask
*cpu_map
)
6007 memset(d
, 0, sizeof(*d
));
6009 if (__sdt_alloc(cpu_map
))
6010 return sa_sd_storage
;
6011 d
->sd
= alloc_percpu(struct sched_domain
*);
6013 return sa_sd_storage
;
6014 d
->rd
= alloc_rootdomain();
6017 return sa_rootdomain
;
6021 * NULL the sd_data elements we've used to build the sched_domain and
6022 * sched_group structure so that the subsequent __free_domain_allocs()
6023 * will not free the data we're using.
6025 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6027 struct sd_data
*sdd
= sd
->private;
6029 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6030 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6032 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6033 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6035 if (atomic_read(&(*per_cpu_ptr(sdd
->sgp
, cpu
))->ref
))
6036 *per_cpu_ptr(sdd
->sgp
, cpu
) = NULL
;
6039 #ifdef CONFIG_SCHED_SMT
6040 static const struct cpumask
*cpu_smt_mask(int cpu
)
6042 return topology_thread_cpumask(cpu
);
6047 * Topology list, bottom-up.
6049 static struct sched_domain_topology_level default_topology
[] = {
6050 #ifdef CONFIG_SCHED_SMT
6051 { sd_init_SIBLING
, cpu_smt_mask
, },
6053 #ifdef CONFIG_SCHED_MC
6054 { sd_init_MC
, cpu_coregroup_mask
, },
6056 #ifdef CONFIG_SCHED_BOOK
6057 { sd_init_BOOK
, cpu_book_mask
, },
6059 { sd_init_CPU
, cpu_cpu_mask
, },
6063 static struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
6067 static int sched_domains_numa_levels
;
6068 static int *sched_domains_numa_distance
;
6069 static struct cpumask
***sched_domains_numa_masks
;
6070 static int sched_domains_curr_level
;
6072 static inline int sd_local_flags(int level
)
6074 if (sched_domains_numa_distance
[level
] > RECLAIM_DISTANCE
)
6077 return SD_BALANCE_EXEC
| SD_BALANCE_FORK
| SD_WAKE_AFFINE
;
6080 static struct sched_domain
*
6081 sd_numa_init(struct sched_domain_topology_level
*tl
, int cpu
)
6083 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6084 int level
= tl
->numa_level
;
6085 int sd_weight
= cpumask_weight(
6086 sched_domains_numa_masks
[level
][cpu_to_node(cpu
)]);
6088 *sd
= (struct sched_domain
){
6089 .min_interval
= sd_weight
,
6090 .max_interval
= 2*sd_weight
,
6092 .imbalance_pct
= 125,
6093 .cache_nice_tries
= 2,
6100 .flags
= 1*SD_LOAD_BALANCE
6101 | 1*SD_BALANCE_NEWIDLE
6106 | 0*SD_SHARE_CPUPOWER
6107 | 0*SD_SHARE_PKG_RESOURCES
6109 | 0*SD_PREFER_SIBLING
6110 | sd_local_flags(level
)
6112 .last_balance
= jiffies
,
6113 .balance_interval
= sd_weight
,
6115 SD_INIT_NAME(sd
, NUMA
);
6116 sd
->private = &tl
->data
;
6119 * Ugly hack to pass state to sd_numa_mask()...
6121 sched_domains_curr_level
= tl
->numa_level
;
6126 static const struct cpumask
*sd_numa_mask(int cpu
)
6128 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6131 static void sched_numa_warn(const char *str
)
6133 static int done
= false;
6141 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6143 for (i
= 0; i
< nr_node_ids
; i
++) {
6144 printk(KERN_WARNING
" ");
6145 for (j
= 0; j
< nr_node_ids
; j
++)
6146 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6147 printk(KERN_CONT
"\n");
6149 printk(KERN_WARNING
"\n");
6152 static bool find_numa_distance(int distance
)
6156 if (distance
== node_distance(0, 0))
6159 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6160 if (sched_domains_numa_distance
[i
] == distance
)
6167 static void sched_init_numa(void)
6169 int next_distance
, curr_distance
= node_distance(0, 0);
6170 struct sched_domain_topology_level
*tl
;
6174 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6175 if (!sched_domains_numa_distance
)
6179 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6180 * unique distances in the node_distance() table.
6182 * Assumes node_distance(0,j) includes all distances in
6183 * node_distance(i,j) in order to avoid cubic time.
6185 next_distance
= curr_distance
;
6186 for (i
= 0; i
< nr_node_ids
; i
++) {
6187 for (j
= 0; j
< nr_node_ids
; j
++) {
6188 for (k
= 0; k
< nr_node_ids
; k
++) {
6189 int distance
= node_distance(i
, k
);
6191 if (distance
> curr_distance
&&
6192 (distance
< next_distance
||
6193 next_distance
== curr_distance
))
6194 next_distance
= distance
;
6197 * While not a strong assumption it would be nice to know
6198 * about cases where if node A is connected to B, B is not
6199 * equally connected to A.
6201 if (sched_debug() && node_distance(k
, i
) != distance
)
6202 sched_numa_warn("Node-distance not symmetric");
6204 if (sched_debug() && i
&& !find_numa_distance(distance
))
6205 sched_numa_warn("Node-0 not representative");
6207 if (next_distance
!= curr_distance
) {
6208 sched_domains_numa_distance
[level
++] = next_distance
;
6209 sched_domains_numa_levels
= level
;
6210 curr_distance
= next_distance
;
6215 * In case of sched_debug() we verify the above assumption.
6221 * 'level' contains the number of unique distances, excluding the
6222 * identity distance node_distance(i,i).
6224 * The sched_domains_nume_distance[] array includes the actual distance
6229 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6230 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6231 * the array will contain less then 'level' members. This could be
6232 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6233 * in other functions.
6235 * We reset it to 'level' at the end of this function.
6237 sched_domains_numa_levels
= 0;
6239 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6240 if (!sched_domains_numa_masks
)
6244 * Now for each level, construct a mask per node which contains all
6245 * cpus of nodes that are that many hops away from us.
6247 for (i
= 0; i
< level
; i
++) {
6248 sched_domains_numa_masks
[i
] =
6249 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6250 if (!sched_domains_numa_masks
[i
])
6253 for (j
= 0; j
< nr_node_ids
; j
++) {
6254 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6258 sched_domains_numa_masks
[i
][j
] = mask
;
6260 for (k
= 0; k
< nr_node_ids
; k
++) {
6261 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6264 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6269 tl
= kzalloc((ARRAY_SIZE(default_topology
) + level
) *
6270 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6275 * Copy the default topology bits..
6277 for (i
= 0; default_topology
[i
].init
; i
++)
6278 tl
[i
] = default_topology
[i
];
6281 * .. and append 'j' levels of NUMA goodness.
6283 for (j
= 0; j
< level
; i
++, j
++) {
6284 tl
[i
] = (struct sched_domain_topology_level
){
6285 .init
= sd_numa_init
,
6286 .mask
= sd_numa_mask
,
6287 .flags
= SDTL_OVERLAP
,
6292 sched_domain_topology
= tl
;
6294 sched_domains_numa_levels
= level
;
6297 static void sched_domains_numa_masks_set(int cpu
)
6300 int node
= cpu_to_node(cpu
);
6302 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6303 for (j
= 0; j
< nr_node_ids
; j
++) {
6304 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6305 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6310 static void sched_domains_numa_masks_clear(int cpu
)
6313 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6314 for (j
= 0; j
< nr_node_ids
; j
++)
6315 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6320 * Update sched_domains_numa_masks[level][node] array when new cpus
6323 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6324 unsigned long action
,
6327 int cpu
= (long)hcpu
;
6329 switch (action
& ~CPU_TASKS_FROZEN
) {
6331 sched_domains_numa_masks_set(cpu
);
6335 sched_domains_numa_masks_clear(cpu
);
6345 static inline void sched_init_numa(void)
6349 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6350 unsigned long action
,
6355 #endif /* CONFIG_NUMA */
6357 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6359 struct sched_domain_topology_level
*tl
;
6362 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6363 struct sd_data
*sdd
= &tl
->data
;
6365 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6369 sdd
->sg
= alloc_percpu(struct sched_group
*);
6373 sdd
->sgp
= alloc_percpu(struct sched_group_power
*);
6377 for_each_cpu(j
, cpu_map
) {
6378 struct sched_domain
*sd
;
6379 struct sched_group
*sg
;
6380 struct sched_group_power
*sgp
;
6382 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6383 GFP_KERNEL
, cpu_to_node(j
));
6387 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6389 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6390 GFP_KERNEL
, cpu_to_node(j
));
6396 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6398 sgp
= kzalloc_node(sizeof(struct sched_group_power
) + cpumask_size(),
6399 GFP_KERNEL
, cpu_to_node(j
));
6403 *per_cpu_ptr(sdd
->sgp
, j
) = sgp
;
6410 static void __sdt_free(const struct cpumask
*cpu_map
)
6412 struct sched_domain_topology_level
*tl
;
6415 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6416 struct sd_data
*sdd
= &tl
->data
;
6418 for_each_cpu(j
, cpu_map
) {
6419 struct sched_domain
*sd
;
6422 sd
= *per_cpu_ptr(sdd
->sd
, j
);
6423 if (sd
&& (sd
->flags
& SD_OVERLAP
))
6424 free_sched_groups(sd
->groups
, 0);
6425 kfree(*per_cpu_ptr(sdd
->sd
, j
));
6429 kfree(*per_cpu_ptr(sdd
->sg
, j
));
6431 kfree(*per_cpu_ptr(sdd
->sgp
, j
));
6433 free_percpu(sdd
->sd
);
6435 free_percpu(sdd
->sg
);
6437 free_percpu(sdd
->sgp
);
6442 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
6443 struct s_data
*d
, const struct cpumask
*cpu_map
,
6444 struct sched_domain_attr
*attr
, struct sched_domain
*child
,
6447 struct sched_domain
*sd
= tl
->init(tl
, cpu
);
6451 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
6453 sd
->level
= child
->level
+ 1;
6454 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
6458 set_domain_attribute(sd
, attr
);
6464 * Build sched domains for a given set of cpus and attach the sched domains
6465 * to the individual cpus
6467 static int build_sched_domains(const struct cpumask
*cpu_map
,
6468 struct sched_domain_attr
*attr
)
6470 enum s_alloc alloc_state
= sa_none
;
6471 struct sched_domain
*sd
;
6473 int i
, ret
= -ENOMEM
;
6475 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
6476 if (alloc_state
!= sa_rootdomain
)
6479 /* Set up domains for cpus specified by the cpu_map. */
6480 for_each_cpu(i
, cpu_map
) {
6481 struct sched_domain_topology_level
*tl
;
6484 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6485 sd
= build_sched_domain(tl
, &d
, cpu_map
, attr
, sd
, i
);
6486 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
6487 sd
->flags
|= SD_OVERLAP
;
6488 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
6495 *per_cpu_ptr(d
.sd
, i
) = sd
;
6498 /* Build the groups for the domains */
6499 for_each_cpu(i
, cpu_map
) {
6500 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6501 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
6502 if (sd
->flags
& SD_OVERLAP
) {
6503 if (build_overlap_sched_groups(sd
, i
))
6506 if (build_sched_groups(sd
, i
))
6512 /* Calculate CPU power for physical packages and nodes */
6513 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
6514 if (!cpumask_test_cpu(i
, cpu_map
))
6517 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6518 claim_allocations(i
, sd
);
6519 init_sched_groups_power(i
, sd
);
6523 /* Attach the domains */
6525 for_each_cpu(i
, cpu_map
) {
6526 sd
= *per_cpu_ptr(d
.sd
, i
);
6527 cpu_attach_domain(sd
, d
.rd
, i
);
6533 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
6537 static cpumask_var_t
*doms_cur
; /* current sched domains */
6538 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6539 static struct sched_domain_attr
*dattr_cur
;
6540 /* attribues of custom domains in 'doms_cur' */
6543 * Special case: If a kmalloc of a doms_cur partition (array of
6544 * cpumask) fails, then fallback to a single sched domain,
6545 * as determined by the single cpumask fallback_doms.
6547 static cpumask_var_t fallback_doms
;
6550 * arch_update_cpu_topology lets virtualized architectures update the
6551 * cpu core maps. It is supposed to return 1 if the topology changed
6552 * or 0 if it stayed the same.
6554 int __attribute__((weak
)) arch_update_cpu_topology(void)
6559 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
6562 cpumask_var_t
*doms
;
6564 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
6567 for (i
= 0; i
< ndoms
; i
++) {
6568 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
6569 free_sched_domains(doms
, i
);
6576 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
6579 for (i
= 0; i
< ndoms
; i
++)
6580 free_cpumask_var(doms
[i
]);
6585 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6586 * For now this just excludes isolated cpus, but could be used to
6587 * exclude other special cases in the future.
6589 static int init_sched_domains(const struct cpumask
*cpu_map
)
6593 arch_update_cpu_topology();
6595 doms_cur
= alloc_sched_domains(ndoms_cur
);
6597 doms_cur
= &fallback_doms
;
6598 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
6599 err
= build_sched_domains(doms_cur
[0], NULL
);
6600 register_sched_domain_sysctl();
6606 * Detach sched domains from a group of cpus specified in cpu_map
6607 * These cpus will now be attached to the NULL domain
6609 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
6614 for_each_cpu(i
, cpu_map
)
6615 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6619 /* handle null as "default" */
6620 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
6621 struct sched_domain_attr
*new, int idx_new
)
6623 struct sched_domain_attr tmp
;
6630 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
6631 new ? (new + idx_new
) : &tmp
,
6632 sizeof(struct sched_domain_attr
));
6636 * Partition sched domains as specified by the 'ndoms_new'
6637 * cpumasks in the array doms_new[] of cpumasks. This compares
6638 * doms_new[] to the current sched domain partitioning, doms_cur[].
6639 * It destroys each deleted domain and builds each new domain.
6641 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6642 * The masks don't intersect (don't overlap.) We should setup one
6643 * sched domain for each mask. CPUs not in any of the cpumasks will
6644 * not be load balanced. If the same cpumask appears both in the
6645 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6648 * The passed in 'doms_new' should be allocated using
6649 * alloc_sched_domains. This routine takes ownership of it and will
6650 * free_sched_domains it when done with it. If the caller failed the
6651 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6652 * and partition_sched_domains() will fallback to the single partition
6653 * 'fallback_doms', it also forces the domains to be rebuilt.
6655 * If doms_new == NULL it will be replaced with cpu_online_mask.
6656 * ndoms_new == 0 is a special case for destroying existing domains,
6657 * and it will not create the default domain.
6659 * Call with hotplug lock held
6661 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
6662 struct sched_domain_attr
*dattr_new
)
6667 mutex_lock(&sched_domains_mutex
);
6669 /* always unregister in case we don't destroy any domains */
6670 unregister_sched_domain_sysctl();
6672 /* Let architecture update cpu core mappings. */
6673 new_topology
= arch_update_cpu_topology();
6675 n
= doms_new
? ndoms_new
: 0;
6677 /* Destroy deleted domains */
6678 for (i
= 0; i
< ndoms_cur
; i
++) {
6679 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6680 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
6681 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
6684 /* no match - a current sched domain not in new doms_new[] */
6685 detach_destroy_domains(doms_cur
[i
]);
6690 if (doms_new
== NULL
) {
6692 doms_new
= &fallback_doms
;
6693 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
6694 WARN_ON_ONCE(dattr_new
);
6697 /* Build new domains */
6698 for (i
= 0; i
< ndoms_new
; i
++) {
6699 for (j
= 0; j
< ndoms_cur
&& !new_topology
; j
++) {
6700 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
6701 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
6704 /* no match - add a new doms_new */
6705 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
6710 /* Remember the new sched domains */
6711 if (doms_cur
!= &fallback_doms
)
6712 free_sched_domains(doms_cur
, ndoms_cur
);
6713 kfree(dattr_cur
); /* kfree(NULL) is safe */
6714 doms_cur
= doms_new
;
6715 dattr_cur
= dattr_new
;
6716 ndoms_cur
= ndoms_new
;
6718 register_sched_domain_sysctl();
6720 mutex_unlock(&sched_domains_mutex
);
6723 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
6726 * Update cpusets according to cpu_active mask. If cpusets are
6727 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6728 * around partition_sched_domains().
6730 * If we come here as part of a suspend/resume, don't touch cpusets because we
6731 * want to restore it back to its original state upon resume anyway.
6733 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
6737 case CPU_ONLINE_FROZEN
:
6738 case CPU_DOWN_FAILED_FROZEN
:
6741 * num_cpus_frozen tracks how many CPUs are involved in suspend
6742 * resume sequence. As long as this is not the last online
6743 * operation in the resume sequence, just build a single sched
6744 * domain, ignoring cpusets.
6747 if (likely(num_cpus_frozen
)) {
6748 partition_sched_domains(1, NULL
, NULL
);
6753 * This is the last CPU online operation. So fall through and
6754 * restore the original sched domains by considering the
6755 * cpuset configurations.
6759 case CPU_DOWN_FAILED
:
6760 cpuset_update_active_cpus(true);
6768 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
6772 case CPU_DOWN_PREPARE
:
6773 cpuset_update_active_cpus(false);
6775 case CPU_DOWN_PREPARE_FROZEN
:
6777 partition_sched_domains(1, NULL
, NULL
);
6785 void __init
sched_init_smp(void)
6787 cpumask_var_t non_isolated_cpus
;
6789 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
6790 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
6795 mutex_lock(&sched_domains_mutex
);
6796 init_sched_domains(cpu_active_mask
);
6797 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
6798 if (cpumask_empty(non_isolated_cpus
))
6799 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
6800 mutex_unlock(&sched_domains_mutex
);
6803 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
6804 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
6805 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
6807 /* RT runtime code needs to handle some hotplug events */
6808 hotcpu_notifier(update_runtime
, 0);
6812 /* Move init over to a non-isolated CPU */
6813 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
6815 sched_init_granularity();
6816 free_cpumask_var(non_isolated_cpus
);
6818 init_sched_rt_class();
6821 void __init
sched_init_smp(void)
6823 sched_init_granularity();
6825 #endif /* CONFIG_SMP */
6827 const_debug
unsigned int sysctl_timer_migration
= 1;
6829 int in_sched_functions(unsigned long addr
)
6831 return in_lock_functions(addr
) ||
6832 (addr
>= (unsigned long)__sched_text_start
6833 && addr
< (unsigned long)__sched_text_end
);
6836 #ifdef CONFIG_CGROUP_SCHED
6837 struct task_group root_task_group
;
6838 LIST_HEAD(task_groups
);
6841 DECLARE_PER_CPU(cpumask_var_t
, load_balance_tmpmask
);
6843 void __init
sched_init(void)
6846 unsigned long alloc_size
= 0, ptr
;
6848 #ifdef CONFIG_FAIR_GROUP_SCHED
6849 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6851 #ifdef CONFIG_RT_GROUP_SCHED
6852 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6854 #ifdef CONFIG_CPUMASK_OFFSTACK
6855 alloc_size
+= num_possible_cpus() * cpumask_size();
6858 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
6860 #ifdef CONFIG_FAIR_GROUP_SCHED
6861 root_task_group
.se
= (struct sched_entity
**)ptr
;
6862 ptr
+= nr_cpu_ids
* sizeof(void **);
6864 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
6865 ptr
+= nr_cpu_ids
* sizeof(void **);
6867 #endif /* CONFIG_FAIR_GROUP_SCHED */
6868 #ifdef CONFIG_RT_GROUP_SCHED
6869 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
6870 ptr
+= nr_cpu_ids
* sizeof(void **);
6872 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
6873 ptr
+= nr_cpu_ids
* sizeof(void **);
6875 #endif /* CONFIG_RT_GROUP_SCHED */
6876 #ifdef CONFIG_CPUMASK_OFFSTACK
6877 for_each_possible_cpu(i
) {
6878 per_cpu(load_balance_tmpmask
, i
) = (void *)ptr
;
6879 ptr
+= cpumask_size();
6881 #endif /* CONFIG_CPUMASK_OFFSTACK */
6885 init_defrootdomain();
6888 init_rt_bandwidth(&def_rt_bandwidth
,
6889 global_rt_period(), global_rt_runtime());
6891 #ifdef CONFIG_RT_GROUP_SCHED
6892 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
6893 global_rt_period(), global_rt_runtime());
6894 #endif /* CONFIG_RT_GROUP_SCHED */
6896 #ifdef CONFIG_CGROUP_SCHED
6897 list_add(&root_task_group
.list
, &task_groups
);
6898 INIT_LIST_HEAD(&root_task_group
.children
);
6899 INIT_LIST_HEAD(&root_task_group
.siblings
);
6900 autogroup_init(&init_task
);
6902 #endif /* CONFIG_CGROUP_SCHED */
6904 #ifdef CONFIG_CGROUP_CPUACCT
6905 root_cpuacct
.cpustat
= &kernel_cpustat
;
6906 root_cpuacct
.cpuusage
= alloc_percpu(u64
);
6907 /* Too early, not expected to fail */
6908 BUG_ON(!root_cpuacct
.cpuusage
);
6910 for_each_possible_cpu(i
) {
6914 raw_spin_lock_init(&rq
->lock
);
6916 rq
->calc_load_active
= 0;
6917 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
6918 init_cfs_rq(&rq
->cfs
);
6919 init_rt_rq(&rq
->rt
, rq
);
6920 #ifdef CONFIG_FAIR_GROUP_SCHED
6921 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
6922 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6924 * How much cpu bandwidth does root_task_group get?
6926 * In case of task-groups formed thr' the cgroup filesystem, it
6927 * gets 100% of the cpu resources in the system. This overall
6928 * system cpu resource is divided among the tasks of
6929 * root_task_group and its child task-groups in a fair manner,
6930 * based on each entity's (task or task-group's) weight
6931 * (se->load.weight).
6933 * In other words, if root_task_group has 10 tasks of weight
6934 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6935 * then A0's share of the cpu resource is:
6937 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6939 * We achieve this by letting root_task_group's tasks sit
6940 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6942 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
6943 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
6944 #endif /* CONFIG_FAIR_GROUP_SCHED */
6946 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
6947 #ifdef CONFIG_RT_GROUP_SCHED
6948 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
6949 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
6952 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6953 rq
->cpu_load
[j
] = 0;
6955 rq
->last_load_update_tick
= jiffies
;
6960 rq
->cpu_power
= SCHED_POWER_SCALE
;
6961 rq
->post_schedule
= 0;
6962 rq
->active_balance
= 0;
6963 rq
->next_balance
= jiffies
;
6968 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
6970 INIT_LIST_HEAD(&rq
->cfs_tasks
);
6972 rq_attach_root(rq
, &def_root_domain
);
6978 atomic_set(&rq
->nr_iowait
, 0);
6981 set_load_weight(&init_task
);
6983 #ifdef CONFIG_PREEMPT_NOTIFIERS
6984 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6987 #ifdef CONFIG_RT_MUTEXES
6988 plist_head_init(&init_task
.pi_waiters
);
6992 * The boot idle thread does lazy MMU switching as well:
6994 atomic_inc(&init_mm
.mm_count
);
6995 enter_lazy_tlb(&init_mm
, current
);
6998 * Make us the idle thread. Technically, schedule() should not be
6999 * called from this thread, however somewhere below it might be,
7000 * but because we are the idle thread, we just pick up running again
7001 * when this runqueue becomes "idle".
7003 init_idle(current
, smp_processor_id());
7005 calc_load_update
= jiffies
+ LOAD_FREQ
;
7008 * During early bootup we pretend to be a normal task:
7010 current
->sched_class
= &fair_sched_class
;
7013 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
7014 /* May be allocated at isolcpus cmdline parse time */
7015 if (cpu_isolated_map
== NULL
)
7016 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
7017 idle_thread_set_boot_cpu();
7019 init_sched_fair_class();
7021 scheduler_running
= 1;
7024 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7025 static inline int preempt_count_equals(int preempt_offset
)
7027 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
7029 return (nested
== preempt_offset
);
7032 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7034 static unsigned long prev_jiffy
; /* ratelimiting */
7036 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7037 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled()) ||
7038 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7040 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7042 prev_jiffy
= jiffies
;
7045 "BUG: sleeping function called from invalid context at %s:%d\n",
7048 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7049 in_atomic(), irqs_disabled(),
7050 current
->pid
, current
->comm
);
7052 debug_show_held_locks(current
);
7053 if (irqs_disabled())
7054 print_irqtrace_events(current
);
7057 EXPORT_SYMBOL(__might_sleep
);
7060 #ifdef CONFIG_MAGIC_SYSRQ
7061 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7063 const struct sched_class
*prev_class
= p
->sched_class
;
7064 int old_prio
= p
->prio
;
7069 dequeue_task(rq
, p
, 0);
7070 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
7072 enqueue_task(rq
, p
, 0);
7073 resched_task(rq
->curr
);
7076 check_class_changed(rq
, p
, prev_class
, old_prio
);
7079 void normalize_rt_tasks(void)
7081 struct task_struct
*g
, *p
;
7082 unsigned long flags
;
7085 read_lock_irqsave(&tasklist_lock
, flags
);
7086 do_each_thread(g
, p
) {
7088 * Only normalize user tasks:
7093 p
->se
.exec_start
= 0;
7094 #ifdef CONFIG_SCHEDSTATS
7095 p
->se
.statistics
.wait_start
= 0;
7096 p
->se
.statistics
.sleep_start
= 0;
7097 p
->se
.statistics
.block_start
= 0;
7102 * Renice negative nice level userspace
7105 if (TASK_NICE(p
) < 0 && p
->mm
)
7106 set_user_nice(p
, 0);
7110 raw_spin_lock(&p
->pi_lock
);
7111 rq
= __task_rq_lock(p
);
7113 normalize_task(rq
, p
);
7115 __task_rq_unlock(rq
);
7116 raw_spin_unlock(&p
->pi_lock
);
7117 } while_each_thread(g
, p
);
7119 read_unlock_irqrestore(&tasklist_lock
, flags
);
7122 #endif /* CONFIG_MAGIC_SYSRQ */
7124 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7126 * These functions are only useful for the IA64 MCA handling, or kdb.
7128 * They can only be called when the whole system has been
7129 * stopped - every CPU needs to be quiescent, and no scheduling
7130 * activity can take place. Using them for anything else would
7131 * be a serious bug, and as a result, they aren't even visible
7132 * under any other configuration.
7136 * curr_task - return the current task for a given cpu.
7137 * @cpu: the processor in question.
7139 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7141 struct task_struct
*curr_task(int cpu
)
7143 return cpu_curr(cpu
);
7146 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7150 * set_curr_task - set the current task for a given cpu.
7151 * @cpu: the processor in question.
7152 * @p: the task pointer to set.
7154 * Description: This function must only be used when non-maskable interrupts
7155 * are serviced on a separate stack. It allows the architecture to switch the
7156 * notion of the current task on a cpu in a non-blocking manner. This function
7157 * must be called with all CPU's synchronized, and interrupts disabled, the
7158 * and caller must save the original value of the current task (see
7159 * curr_task() above) and restore that value before reenabling interrupts and
7160 * re-starting the system.
7162 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7164 void set_curr_task(int cpu
, struct task_struct
*p
)
7171 #ifdef CONFIG_CGROUP_SCHED
7172 /* task_group_lock serializes the addition/removal of task groups */
7173 static DEFINE_SPINLOCK(task_group_lock
);
7175 static void free_sched_group(struct task_group
*tg
)
7177 free_fair_sched_group(tg
);
7178 free_rt_sched_group(tg
);
7183 /* allocate runqueue etc for a new task group */
7184 struct task_group
*sched_create_group(struct task_group
*parent
)
7186 struct task_group
*tg
;
7188 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7190 return ERR_PTR(-ENOMEM
);
7192 if (!alloc_fair_sched_group(tg
, parent
))
7195 if (!alloc_rt_sched_group(tg
, parent
))
7201 free_sched_group(tg
);
7202 return ERR_PTR(-ENOMEM
);
7205 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7207 unsigned long flags
;
7209 spin_lock_irqsave(&task_group_lock
, flags
);
7210 list_add_rcu(&tg
->list
, &task_groups
);
7212 WARN_ON(!parent
); /* root should already exist */
7214 tg
->parent
= parent
;
7215 INIT_LIST_HEAD(&tg
->children
);
7216 list_add_rcu(&tg
->siblings
, &parent
->children
);
7217 spin_unlock_irqrestore(&task_group_lock
, flags
);
7220 /* rcu callback to free various structures associated with a task group */
7221 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7223 /* now it should be safe to free those cfs_rqs */
7224 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7227 /* Destroy runqueue etc associated with a task group */
7228 void sched_destroy_group(struct task_group
*tg
)
7230 /* wait for possible concurrent references to cfs_rqs complete */
7231 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7234 void sched_offline_group(struct task_group
*tg
)
7236 unsigned long flags
;
7239 /* end participation in shares distribution */
7240 for_each_possible_cpu(i
)
7241 unregister_fair_sched_group(tg
, i
);
7243 spin_lock_irqsave(&task_group_lock
, flags
);
7244 list_del_rcu(&tg
->list
);
7245 list_del_rcu(&tg
->siblings
);
7246 spin_unlock_irqrestore(&task_group_lock
, flags
);
7249 /* change task's runqueue when it moves between groups.
7250 * The caller of this function should have put the task in its new group
7251 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7252 * reflect its new group.
7254 void sched_move_task(struct task_struct
*tsk
)
7256 struct task_group
*tg
;
7258 unsigned long flags
;
7261 rq
= task_rq_lock(tsk
, &flags
);
7263 running
= task_current(rq
, tsk
);
7267 dequeue_task(rq
, tsk
, 0);
7268 if (unlikely(running
))
7269 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7271 tg
= container_of(task_subsys_state_check(tsk
, cpu_cgroup_subsys_id
,
7272 lockdep_is_held(&tsk
->sighand
->siglock
)),
7273 struct task_group
, css
);
7274 tg
= autogroup_task_group(tsk
, tg
);
7275 tsk
->sched_task_group
= tg
;
7277 #ifdef CONFIG_FAIR_GROUP_SCHED
7278 if (tsk
->sched_class
->task_move_group
)
7279 tsk
->sched_class
->task_move_group(tsk
, on_rq
);
7282 set_task_rq(tsk
, task_cpu(tsk
));
7284 if (unlikely(running
))
7285 tsk
->sched_class
->set_curr_task(rq
);
7287 enqueue_task(rq
, tsk
, 0);
7289 task_rq_unlock(rq
, tsk
, &flags
);
7291 #endif /* CONFIG_CGROUP_SCHED */
7293 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
7294 static unsigned long to_ratio(u64 period
, u64 runtime
)
7296 if (runtime
== RUNTIME_INF
)
7299 return div64_u64(runtime
<< 20, period
);
7303 #ifdef CONFIG_RT_GROUP_SCHED
7305 * Ensure that the real time constraints are schedulable.
7307 static DEFINE_MUTEX(rt_constraints_mutex
);
7309 /* Must be called with tasklist_lock held */
7310 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7312 struct task_struct
*g
, *p
;
7314 do_each_thread(g
, p
) {
7315 if (rt_task(p
) && task_rq(p
)->rt
.tg
== tg
)
7317 } while_each_thread(g
, p
);
7322 struct rt_schedulable_data
{
7323 struct task_group
*tg
;
7328 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7330 struct rt_schedulable_data
*d
= data
;
7331 struct task_group
*child
;
7332 unsigned long total
, sum
= 0;
7333 u64 period
, runtime
;
7335 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7336 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7339 period
= d
->rt_period
;
7340 runtime
= d
->rt_runtime
;
7344 * Cannot have more runtime than the period.
7346 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7350 * Ensure we don't starve existing RT tasks.
7352 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7355 total
= to_ratio(period
, runtime
);
7358 * Nobody can have more than the global setting allows.
7360 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7364 * The sum of our children's runtime should not exceed our own.
7366 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7367 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7368 runtime
= child
->rt_bandwidth
.rt_runtime
;
7370 if (child
== d
->tg
) {
7371 period
= d
->rt_period
;
7372 runtime
= d
->rt_runtime
;
7375 sum
+= to_ratio(period
, runtime
);
7384 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7388 struct rt_schedulable_data data
= {
7390 .rt_period
= period
,
7391 .rt_runtime
= runtime
,
7395 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
7401 static int tg_set_rt_bandwidth(struct task_group
*tg
,
7402 u64 rt_period
, u64 rt_runtime
)
7406 mutex_lock(&rt_constraints_mutex
);
7407 read_lock(&tasklist_lock
);
7408 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
7412 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7413 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
7414 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
7416 for_each_possible_cpu(i
) {
7417 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
7419 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7420 rt_rq
->rt_runtime
= rt_runtime
;
7421 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7423 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7425 read_unlock(&tasklist_lock
);
7426 mutex_unlock(&rt_constraints_mutex
);
7431 int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7433 u64 rt_runtime
, rt_period
;
7435 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7436 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7437 if (rt_runtime_us
< 0)
7438 rt_runtime
= RUNTIME_INF
;
7440 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7443 long sched_group_rt_runtime(struct task_group
*tg
)
7447 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
7450 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
7451 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7452 return rt_runtime_us
;
7455 int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
7457 u64 rt_runtime
, rt_period
;
7459 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
7460 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
7465 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7468 long sched_group_rt_period(struct task_group
*tg
)
7472 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7473 do_div(rt_period_us
, NSEC_PER_USEC
);
7474 return rt_period_us
;
7477 static int sched_rt_global_constraints(void)
7479 u64 runtime
, period
;
7482 if (sysctl_sched_rt_period
<= 0)
7485 runtime
= global_rt_runtime();
7486 period
= global_rt_period();
7489 * Sanity check on the sysctl variables.
7491 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7494 mutex_lock(&rt_constraints_mutex
);
7495 read_lock(&tasklist_lock
);
7496 ret
= __rt_schedulable(NULL
, 0, 0);
7497 read_unlock(&tasklist_lock
);
7498 mutex_unlock(&rt_constraints_mutex
);
7503 int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
7505 /* Don't accept realtime tasks when there is no way for them to run */
7506 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
7512 #else /* !CONFIG_RT_GROUP_SCHED */
7513 static int sched_rt_global_constraints(void)
7515 unsigned long flags
;
7518 if (sysctl_sched_rt_period
<= 0)
7522 * There's always some RT tasks in the root group
7523 * -- migration, kstopmachine etc..
7525 if (sysctl_sched_rt_runtime
== 0)
7528 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7529 for_each_possible_cpu(i
) {
7530 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
7532 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7533 rt_rq
->rt_runtime
= global_rt_runtime();
7534 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7536 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7540 #endif /* CONFIG_RT_GROUP_SCHED */
7542 int sched_rr_handler(struct ctl_table
*table
, int write
,
7543 void __user
*buffer
, size_t *lenp
,
7547 static DEFINE_MUTEX(mutex
);
7550 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7551 /* make sure that internally we keep jiffies */
7552 /* also, writing zero resets timeslice to default */
7553 if (!ret
&& write
) {
7554 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
7555 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
7557 mutex_unlock(&mutex
);
7561 int sched_rt_handler(struct ctl_table
*table
, int write
,
7562 void __user
*buffer
, size_t *lenp
,
7566 int old_period
, old_runtime
;
7567 static DEFINE_MUTEX(mutex
);
7570 old_period
= sysctl_sched_rt_period
;
7571 old_runtime
= sysctl_sched_rt_runtime
;
7573 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7575 if (!ret
&& write
) {
7576 ret
= sched_rt_global_constraints();
7578 sysctl_sched_rt_period
= old_period
;
7579 sysctl_sched_rt_runtime
= old_runtime
;
7581 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
7582 def_rt_bandwidth
.rt_period
=
7583 ns_to_ktime(global_rt_period());
7586 mutex_unlock(&mutex
);
7591 #ifdef CONFIG_CGROUP_SCHED
7593 /* return corresponding task_group object of a cgroup */
7594 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7596 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7597 struct task_group
, css
);
7600 static struct cgroup_subsys_state
*cpu_cgroup_css_alloc(struct cgroup
*cgrp
)
7602 struct task_group
*tg
, *parent
;
7604 if (!cgrp
->parent
) {
7605 /* This is early initialization for the top cgroup */
7606 return &root_task_group
.css
;
7609 parent
= cgroup_tg(cgrp
->parent
);
7610 tg
= sched_create_group(parent
);
7612 return ERR_PTR(-ENOMEM
);
7617 static int cpu_cgroup_css_online(struct cgroup
*cgrp
)
7619 struct task_group
*tg
= cgroup_tg(cgrp
);
7620 struct task_group
*parent
;
7625 parent
= cgroup_tg(cgrp
->parent
);
7626 sched_online_group(tg
, parent
);
7630 static void cpu_cgroup_css_free(struct cgroup
*cgrp
)
7632 struct task_group
*tg
= cgroup_tg(cgrp
);
7634 sched_destroy_group(tg
);
7637 static void cpu_cgroup_css_offline(struct cgroup
*cgrp
)
7639 struct task_group
*tg
= cgroup_tg(cgrp
);
7641 sched_offline_group(tg
);
7644 static int cpu_cgroup_can_attach(struct cgroup
*cgrp
,
7645 struct cgroup_taskset
*tset
)
7647 struct task_struct
*task
;
7649 cgroup_taskset_for_each(task
, cgrp
, tset
) {
7650 #ifdef CONFIG_RT_GROUP_SCHED
7651 if (!sched_rt_can_attach(cgroup_tg(cgrp
), task
))
7654 /* We don't support RT-tasks being in separate groups */
7655 if (task
->sched_class
!= &fair_sched_class
)
7662 static void cpu_cgroup_attach(struct cgroup
*cgrp
,
7663 struct cgroup_taskset
*tset
)
7665 struct task_struct
*task
;
7667 cgroup_taskset_for_each(task
, cgrp
, tset
)
7668 sched_move_task(task
);
7672 cpu_cgroup_exit(struct cgroup
*cgrp
, struct cgroup
*old_cgrp
,
7673 struct task_struct
*task
)
7676 * cgroup_exit() is called in the copy_process() failure path.
7677 * Ignore this case since the task hasn't ran yet, this avoids
7678 * trying to poke a half freed task state from generic code.
7680 if (!(task
->flags
& PF_EXITING
))
7683 sched_move_task(task
);
7686 #ifdef CONFIG_FAIR_GROUP_SCHED
7687 static int cpu_shares_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7690 return sched_group_set_shares(cgroup_tg(cgrp
), scale_load(shareval
));
7693 static u64
cpu_shares_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7695 struct task_group
*tg
= cgroup_tg(cgrp
);
7697 return (u64
) scale_load_down(tg
->shares
);
7700 #ifdef CONFIG_CFS_BANDWIDTH
7701 static DEFINE_MUTEX(cfs_constraints_mutex
);
7703 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
7704 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
7706 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
7708 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
7710 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
7711 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7713 if (tg
== &root_task_group
)
7717 * Ensure we have at some amount of bandwidth every period. This is
7718 * to prevent reaching a state of large arrears when throttled via
7719 * entity_tick() resulting in prolonged exit starvation.
7721 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
7725 * Likewise, bound things on the otherside by preventing insane quota
7726 * periods. This also allows us to normalize in computing quota
7729 if (period
> max_cfs_quota_period
)
7732 mutex_lock(&cfs_constraints_mutex
);
7733 ret
= __cfs_schedulable(tg
, period
, quota
);
7737 runtime_enabled
= quota
!= RUNTIME_INF
;
7738 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
7739 account_cfs_bandwidth_used(runtime_enabled
, runtime_was_enabled
);
7740 raw_spin_lock_irq(&cfs_b
->lock
);
7741 cfs_b
->period
= ns_to_ktime(period
);
7742 cfs_b
->quota
= quota
;
7744 __refill_cfs_bandwidth_runtime(cfs_b
);
7745 /* restart the period timer (if active) to handle new period expiry */
7746 if (runtime_enabled
&& cfs_b
->timer_active
) {
7747 /* force a reprogram */
7748 cfs_b
->timer_active
= 0;
7749 __start_cfs_bandwidth(cfs_b
);
7751 raw_spin_unlock_irq(&cfs_b
->lock
);
7753 for_each_possible_cpu(i
) {
7754 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
7755 struct rq
*rq
= cfs_rq
->rq
;
7757 raw_spin_lock_irq(&rq
->lock
);
7758 cfs_rq
->runtime_enabled
= runtime_enabled
;
7759 cfs_rq
->runtime_remaining
= 0;
7761 if (cfs_rq
->throttled
)
7762 unthrottle_cfs_rq(cfs_rq
);
7763 raw_spin_unlock_irq(&rq
->lock
);
7766 mutex_unlock(&cfs_constraints_mutex
);
7771 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
7775 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7776 if (cfs_quota_us
< 0)
7777 quota
= RUNTIME_INF
;
7779 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
7781 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7784 long tg_get_cfs_quota(struct task_group
*tg
)
7788 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
7791 quota_us
= tg
->cfs_bandwidth
.quota
;
7792 do_div(quota_us
, NSEC_PER_USEC
);
7797 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
7801 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
7802 quota
= tg
->cfs_bandwidth
.quota
;
7804 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7807 long tg_get_cfs_period(struct task_group
*tg
)
7811 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7812 do_div(cfs_period_us
, NSEC_PER_USEC
);
7814 return cfs_period_us
;
7817 static s64
cpu_cfs_quota_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
)
7819 return tg_get_cfs_quota(cgroup_tg(cgrp
));
7822 static int cpu_cfs_quota_write_s64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7825 return tg_set_cfs_quota(cgroup_tg(cgrp
), cfs_quota_us
);
7828 static u64
cpu_cfs_period_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7830 return tg_get_cfs_period(cgroup_tg(cgrp
));
7833 static int cpu_cfs_period_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7836 return tg_set_cfs_period(cgroup_tg(cgrp
), cfs_period_us
);
7839 struct cfs_schedulable_data
{
7840 struct task_group
*tg
;
7845 * normalize group quota/period to be quota/max_period
7846 * note: units are usecs
7848 static u64
normalize_cfs_quota(struct task_group
*tg
,
7849 struct cfs_schedulable_data
*d
)
7857 period
= tg_get_cfs_period(tg
);
7858 quota
= tg_get_cfs_quota(tg
);
7861 /* note: these should typically be equivalent */
7862 if (quota
== RUNTIME_INF
|| quota
== -1)
7865 return to_ratio(period
, quota
);
7868 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
7870 struct cfs_schedulable_data
*d
= data
;
7871 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7872 s64 quota
= 0, parent_quota
= -1;
7875 quota
= RUNTIME_INF
;
7877 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
7879 quota
= normalize_cfs_quota(tg
, d
);
7880 parent_quota
= parent_b
->hierarchal_quota
;
7883 * ensure max(child_quota) <= parent_quota, inherit when no
7886 if (quota
== RUNTIME_INF
)
7887 quota
= parent_quota
;
7888 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
7891 cfs_b
->hierarchal_quota
= quota
;
7896 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
7899 struct cfs_schedulable_data data
= {
7905 if (quota
!= RUNTIME_INF
) {
7906 do_div(data
.period
, NSEC_PER_USEC
);
7907 do_div(data
.quota
, NSEC_PER_USEC
);
7911 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
7917 static int cpu_stats_show(struct cgroup
*cgrp
, struct cftype
*cft
,
7918 struct cgroup_map_cb
*cb
)
7920 struct task_group
*tg
= cgroup_tg(cgrp
);
7921 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7923 cb
->fill(cb
, "nr_periods", cfs_b
->nr_periods
);
7924 cb
->fill(cb
, "nr_throttled", cfs_b
->nr_throttled
);
7925 cb
->fill(cb
, "throttled_time", cfs_b
->throttled_time
);
7929 #endif /* CONFIG_CFS_BANDWIDTH */
7930 #endif /* CONFIG_FAIR_GROUP_SCHED */
7932 #ifdef CONFIG_RT_GROUP_SCHED
7933 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
7936 return sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
7939 static s64
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
)
7941 return sched_group_rt_runtime(cgroup_tg(cgrp
));
7944 static int cpu_rt_period_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
7947 return sched_group_set_rt_period(cgroup_tg(cgrp
), rt_period_us
);
7950 static u64
cpu_rt_period_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
7952 return sched_group_rt_period(cgroup_tg(cgrp
));
7954 #endif /* CONFIG_RT_GROUP_SCHED */
7956 static struct cftype cpu_files
[] = {
7957 #ifdef CONFIG_FAIR_GROUP_SCHED
7960 .read_u64
= cpu_shares_read_u64
,
7961 .write_u64
= cpu_shares_write_u64
,
7964 #ifdef CONFIG_CFS_BANDWIDTH
7966 .name
= "cfs_quota_us",
7967 .read_s64
= cpu_cfs_quota_read_s64
,
7968 .write_s64
= cpu_cfs_quota_write_s64
,
7971 .name
= "cfs_period_us",
7972 .read_u64
= cpu_cfs_period_read_u64
,
7973 .write_u64
= cpu_cfs_period_write_u64
,
7977 .read_map
= cpu_stats_show
,
7980 #ifdef CONFIG_RT_GROUP_SCHED
7982 .name
= "rt_runtime_us",
7983 .read_s64
= cpu_rt_runtime_read
,
7984 .write_s64
= cpu_rt_runtime_write
,
7987 .name
= "rt_period_us",
7988 .read_u64
= cpu_rt_period_read_uint
,
7989 .write_u64
= cpu_rt_period_write_uint
,
7995 struct cgroup_subsys cpu_cgroup_subsys
= {
7997 .css_alloc
= cpu_cgroup_css_alloc
,
7998 .css_free
= cpu_cgroup_css_free
,
7999 .css_online
= cpu_cgroup_css_online
,
8000 .css_offline
= cpu_cgroup_css_offline
,
8001 .can_attach
= cpu_cgroup_can_attach
,
8002 .attach
= cpu_cgroup_attach
,
8003 .exit
= cpu_cgroup_exit
,
8004 .subsys_id
= cpu_cgroup_subsys_id
,
8005 .base_cftypes
= cpu_files
,
8009 #endif /* CONFIG_CGROUP_SCHED */
8011 #ifdef CONFIG_CGROUP_CPUACCT
8014 * CPU accounting code for task groups.
8016 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
8017 * (balbir@in.ibm.com).
8020 struct cpuacct root_cpuacct
;
8022 /* create a new cpu accounting group */
8023 static struct cgroup_subsys_state
*cpuacct_css_alloc(struct cgroup
*cgrp
)
8028 return &root_cpuacct
.css
;
8030 ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
8034 ca
->cpuusage
= alloc_percpu(u64
);
8038 ca
->cpustat
= alloc_percpu(struct kernel_cpustat
);
8040 goto out_free_cpuusage
;
8045 free_percpu(ca
->cpuusage
);
8049 return ERR_PTR(-ENOMEM
);
8052 /* destroy an existing cpu accounting group */
8053 static void cpuacct_css_free(struct cgroup
*cgrp
)
8055 struct cpuacct
*ca
= cgroup_ca(cgrp
);
8057 free_percpu(ca
->cpustat
);
8058 free_percpu(ca
->cpuusage
);
8062 static u64
cpuacct_cpuusage_read(struct cpuacct
*ca
, int cpu
)
8064 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
8067 #ifndef CONFIG_64BIT
8069 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
8071 raw_spin_lock_irq(&cpu_rq(cpu
)->lock
);
8073 raw_spin_unlock_irq(&cpu_rq(cpu
)->lock
);
8081 static void cpuacct_cpuusage_write(struct cpuacct
*ca
, int cpu
, u64 val
)
8083 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
8085 #ifndef CONFIG_64BIT
8087 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
8089 raw_spin_lock_irq(&cpu_rq(cpu
)->lock
);
8091 raw_spin_unlock_irq(&cpu_rq(cpu
)->lock
);
8097 /* return total cpu usage (in nanoseconds) of a group */
8098 static u64
cpuusage_read(struct cgroup
*cgrp
, struct cftype
*cft
)
8100 struct cpuacct
*ca
= cgroup_ca(cgrp
);
8101 u64 totalcpuusage
= 0;
8104 for_each_present_cpu(i
)
8105 totalcpuusage
+= cpuacct_cpuusage_read(ca
, i
);
8107 return totalcpuusage
;
8110 static int cpuusage_write(struct cgroup
*cgrp
, struct cftype
*cftype
,
8113 struct cpuacct
*ca
= cgroup_ca(cgrp
);
8122 for_each_present_cpu(i
)
8123 cpuacct_cpuusage_write(ca
, i
, 0);
8129 static int cpuacct_percpu_seq_read(struct cgroup
*cgroup
, struct cftype
*cft
,
8132 struct cpuacct
*ca
= cgroup_ca(cgroup
);
8136 for_each_present_cpu(i
) {
8137 percpu
= cpuacct_cpuusage_read(ca
, i
);
8138 seq_printf(m
, "%llu ", (unsigned long long) percpu
);
8140 seq_printf(m
, "\n");
8144 static const char *cpuacct_stat_desc
[] = {
8145 [CPUACCT_STAT_USER
] = "user",
8146 [CPUACCT_STAT_SYSTEM
] = "system",
8149 static int cpuacct_stats_show(struct cgroup
*cgrp
, struct cftype
*cft
,
8150 struct cgroup_map_cb
*cb
)
8152 struct cpuacct
*ca
= cgroup_ca(cgrp
);
8156 for_each_online_cpu(cpu
) {
8157 struct kernel_cpustat
*kcpustat
= per_cpu_ptr(ca
->cpustat
, cpu
);
8158 val
+= kcpustat
->cpustat
[CPUTIME_USER
];
8159 val
+= kcpustat
->cpustat
[CPUTIME_NICE
];
8161 val
= cputime64_to_clock_t(val
);
8162 cb
->fill(cb
, cpuacct_stat_desc
[CPUACCT_STAT_USER
], val
);
8165 for_each_online_cpu(cpu
) {
8166 struct kernel_cpustat
*kcpustat
= per_cpu_ptr(ca
->cpustat
, cpu
);
8167 val
+= kcpustat
->cpustat
[CPUTIME_SYSTEM
];
8168 val
+= kcpustat
->cpustat
[CPUTIME_IRQ
];
8169 val
+= kcpustat
->cpustat
[CPUTIME_SOFTIRQ
];
8172 val
= cputime64_to_clock_t(val
);
8173 cb
->fill(cb
, cpuacct_stat_desc
[CPUACCT_STAT_SYSTEM
], val
);
8178 static struct cftype files
[] = {
8181 .read_u64
= cpuusage_read
,
8182 .write_u64
= cpuusage_write
,
8185 .name
= "usage_percpu",
8186 .read_seq_string
= cpuacct_percpu_seq_read
,
8190 .read_map
= cpuacct_stats_show
,
8196 * charge this task's execution time to its accounting group.
8198 * called with rq->lock held.
8200 void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
)
8205 if (unlikely(!cpuacct_subsys
.active
))
8208 cpu
= task_cpu(tsk
);
8214 for (; ca
; ca
= parent_ca(ca
)) {
8215 u64
*cpuusage
= per_cpu_ptr(ca
->cpuusage
, cpu
);
8216 *cpuusage
+= cputime
;
8222 struct cgroup_subsys cpuacct_subsys
= {
8224 .css_alloc
= cpuacct_css_alloc
,
8225 .css_free
= cpuacct_css_free
,
8226 .subsys_id
= cpuacct_subsys_id
,
8227 .base_cftypes
= files
,
8229 #endif /* CONFIG_CGROUP_CPUACCT */
8231 void dump_cpu_task(int cpu
)
8233 pr_info("Task dump for CPU %d:\n", cpu
);
8234 sched_show_task(cpu_curr(cpu
));