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.
375 static void hrtick_clear(struct rq
*rq
)
377 if (hrtimer_active(&rq
->hrtick_timer
))
378 hrtimer_cancel(&rq
->hrtick_timer
);
382 * High-resolution timer tick.
383 * Runs from hardirq context with interrupts disabled.
385 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
387 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
389 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
391 raw_spin_lock(&rq
->lock
);
393 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
394 raw_spin_unlock(&rq
->lock
);
396 return HRTIMER_NORESTART
;
401 static int __hrtick_restart(struct rq
*rq
)
403 struct hrtimer
*timer
= &rq
->hrtick_timer
;
404 ktime_t time
= hrtimer_get_softexpires(timer
);
406 return __hrtimer_start_range_ns(timer
, time
, 0, HRTIMER_MODE_ABS_PINNED
, 0);
410 * called from hardirq (IPI) context
412 static void __hrtick_start(void *arg
)
416 raw_spin_lock(&rq
->lock
);
417 __hrtick_restart(rq
);
418 rq
->hrtick_csd_pending
= 0;
419 raw_spin_unlock(&rq
->lock
);
423 * Called to set the hrtick timer state.
425 * called with rq->lock held and irqs disabled
427 void hrtick_start(struct rq
*rq
, u64 delay
)
429 struct hrtimer
*timer
= &rq
->hrtick_timer
;
430 ktime_t time
= ktime_add_ns(timer
->base
->get_time(), delay
);
432 hrtimer_set_expires(timer
, time
);
434 if (rq
== this_rq()) {
435 __hrtick_restart(rq
);
436 } else if (!rq
->hrtick_csd_pending
) {
437 __smp_call_function_single(cpu_of(rq
), &rq
->hrtick_csd
, 0);
438 rq
->hrtick_csd_pending
= 1;
443 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
445 int cpu
= (int)(long)hcpu
;
448 case CPU_UP_CANCELED
:
449 case CPU_UP_CANCELED_FROZEN
:
450 case CPU_DOWN_PREPARE
:
451 case CPU_DOWN_PREPARE_FROZEN
:
453 case CPU_DEAD_FROZEN
:
454 hrtick_clear(cpu_rq(cpu
));
461 static __init
void init_hrtick(void)
463 hotcpu_notifier(hotplug_hrtick
, 0);
467 * Called to set the hrtick timer state.
469 * called with rq->lock held and irqs disabled
471 void hrtick_start(struct rq
*rq
, u64 delay
)
473 __hrtimer_start_range_ns(&rq
->hrtick_timer
, ns_to_ktime(delay
), 0,
474 HRTIMER_MODE_REL_PINNED
, 0);
477 static inline void init_hrtick(void)
480 #endif /* CONFIG_SMP */
482 static void init_rq_hrtick(struct rq
*rq
)
485 rq
->hrtick_csd_pending
= 0;
487 rq
->hrtick_csd
.flags
= 0;
488 rq
->hrtick_csd
.func
= __hrtick_start
;
489 rq
->hrtick_csd
.info
= rq
;
492 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
493 rq
->hrtick_timer
.function
= hrtick
;
495 #else /* CONFIG_SCHED_HRTICK */
496 static inline void hrtick_clear(struct rq
*rq
)
500 static inline void init_rq_hrtick(struct rq
*rq
)
504 static inline void init_hrtick(void)
507 #endif /* CONFIG_SCHED_HRTICK */
510 * resched_task - mark a task 'to be rescheduled now'.
512 * On UP this means the setting of the need_resched flag, on SMP it
513 * might also involve a cross-CPU call to trigger the scheduler on
516 void resched_task(struct task_struct
*p
)
520 lockdep_assert_held(&task_rq(p
)->lock
);
522 if (test_tsk_need_resched(p
))
525 set_tsk_need_resched(p
);
528 if (cpu
== smp_processor_id()) {
529 set_preempt_need_resched();
533 /* NEED_RESCHED must be visible before we test polling */
535 if (!tsk_is_polling(p
))
536 smp_send_reschedule(cpu
);
539 void resched_cpu(int cpu
)
541 struct rq
*rq
= cpu_rq(cpu
);
544 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
546 resched_task(cpu_curr(cpu
));
547 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
551 #ifdef CONFIG_NO_HZ_COMMON
553 * In the semi idle case, use the nearest busy cpu for migrating timers
554 * from an idle cpu. This is good for power-savings.
556 * We don't do similar optimization for completely idle system, as
557 * selecting an idle cpu will add more delays to the timers than intended
558 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
560 int get_nohz_timer_target(void)
562 int cpu
= smp_processor_id();
564 struct sched_domain
*sd
;
567 for_each_domain(cpu
, sd
) {
568 for_each_cpu(i
, sched_domain_span(sd
)) {
580 * When add_timer_on() enqueues a timer into the timer wheel of an
581 * idle CPU then this timer might expire before the next timer event
582 * which is scheduled to wake up that CPU. In case of a completely
583 * idle system the next event might even be infinite time into the
584 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
585 * leaves the inner idle loop so the newly added timer is taken into
586 * account when the CPU goes back to idle and evaluates the timer
587 * wheel for the next timer event.
589 static void wake_up_idle_cpu(int cpu
)
591 struct rq
*rq
= cpu_rq(cpu
);
593 if (cpu
== smp_processor_id())
597 * This is safe, as this function is called with the timer
598 * wheel base lock of (cpu) held. When the CPU is on the way
599 * to idle and has not yet set rq->curr to idle then it will
600 * be serialized on the timer wheel base lock and take the new
601 * timer into account automatically.
603 if (rq
->curr
!= rq
->idle
)
607 * We can set TIF_RESCHED on the idle task of the other CPU
608 * lockless. The worst case is that the other CPU runs the
609 * idle task through an additional NOOP schedule()
611 set_tsk_need_resched(rq
->idle
);
613 /* NEED_RESCHED must be visible before we test polling */
615 if (!tsk_is_polling(rq
->idle
))
616 smp_send_reschedule(cpu
);
619 static bool wake_up_full_nohz_cpu(int cpu
)
621 if (tick_nohz_full_cpu(cpu
)) {
622 if (cpu
!= smp_processor_id() ||
623 tick_nohz_tick_stopped())
624 smp_send_reschedule(cpu
);
631 void wake_up_nohz_cpu(int cpu
)
633 if (!wake_up_full_nohz_cpu(cpu
))
634 wake_up_idle_cpu(cpu
);
637 static inline bool got_nohz_idle_kick(void)
639 int cpu
= smp_processor_id();
641 if (!test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
)))
644 if (idle_cpu(cpu
) && !need_resched())
648 * We can't run Idle Load Balance on this CPU for this time so we
649 * cancel it and clear NOHZ_BALANCE_KICK
651 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
655 #else /* CONFIG_NO_HZ_COMMON */
657 static inline bool got_nohz_idle_kick(void)
662 #endif /* CONFIG_NO_HZ_COMMON */
664 #ifdef CONFIG_NO_HZ_FULL
665 bool sched_can_stop_tick(void)
671 /* Make sure rq->nr_running update is visible after the IPI */
674 /* More than one running task need preemption */
675 if (rq
->nr_running
> 1)
680 #endif /* CONFIG_NO_HZ_FULL */
682 void sched_avg_update(struct rq
*rq
)
684 s64 period
= sched_avg_period();
686 while ((s64
)(rq_clock(rq
) - rq
->age_stamp
) > period
) {
688 * Inline assembly required to prevent the compiler
689 * optimising this loop into a divmod call.
690 * See __iter_div_u64_rem() for another example of this.
692 asm("" : "+rm" (rq
->age_stamp
));
693 rq
->age_stamp
+= period
;
698 #endif /* CONFIG_SMP */
700 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
701 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
703 * Iterate task_group tree rooted at *from, calling @down when first entering a
704 * node and @up when leaving it for the final time.
706 * Caller must hold rcu_lock or sufficient equivalent.
708 int walk_tg_tree_from(struct task_group
*from
,
709 tg_visitor down
, tg_visitor up
, void *data
)
711 struct task_group
*parent
, *child
;
717 ret
= (*down
)(parent
, data
);
720 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
727 ret
= (*up
)(parent
, data
);
728 if (ret
|| parent
== from
)
732 parent
= parent
->parent
;
739 int tg_nop(struct task_group
*tg
, void *data
)
745 static void set_load_weight(struct task_struct
*p
)
747 int prio
= p
->static_prio
- MAX_RT_PRIO
;
748 struct load_weight
*load
= &p
->se
.load
;
751 * SCHED_IDLE tasks get minimal weight:
753 if (p
->policy
== SCHED_IDLE
) {
754 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
755 load
->inv_weight
= WMULT_IDLEPRIO
;
759 load
->weight
= scale_load(prio_to_weight
[prio
]);
760 load
->inv_weight
= prio_to_wmult
[prio
];
763 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
766 sched_info_queued(rq
, p
);
767 p
->sched_class
->enqueue_task(rq
, p
, flags
);
770 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
773 sched_info_dequeued(rq
, p
);
774 p
->sched_class
->dequeue_task(rq
, p
, flags
);
777 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
779 if (task_contributes_to_load(p
))
780 rq
->nr_uninterruptible
--;
782 enqueue_task(rq
, p
, flags
);
785 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
787 if (task_contributes_to_load(p
))
788 rq
->nr_uninterruptible
++;
790 dequeue_task(rq
, p
, flags
);
793 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
796 * In theory, the compile should just see 0 here, and optimize out the call
797 * to sched_rt_avg_update. But I don't trust it...
799 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
800 s64 steal
= 0, irq_delta
= 0;
802 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
803 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
806 * Since irq_time is only updated on {soft,}irq_exit, we might run into
807 * this case when a previous update_rq_clock() happened inside a
810 * When this happens, we stop ->clock_task and only update the
811 * prev_irq_time stamp to account for the part that fit, so that a next
812 * update will consume the rest. This ensures ->clock_task is
815 * It does however cause some slight miss-attribution of {soft,}irq
816 * time, a more accurate solution would be to update the irq_time using
817 * the current rq->clock timestamp, except that would require using
820 if (irq_delta
> delta
)
823 rq
->prev_irq_time
+= irq_delta
;
826 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
827 if (static_key_false((¶virt_steal_rq_enabled
))) {
830 steal
= paravirt_steal_clock(cpu_of(rq
));
831 steal
-= rq
->prev_steal_time_rq
;
833 if (unlikely(steal
> delta
))
836 st
= steal_ticks(steal
);
837 steal
= st
* TICK_NSEC
;
839 rq
->prev_steal_time_rq
+= steal
;
845 rq
->clock_task
+= delta
;
847 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
848 if ((irq_delta
+ steal
) && sched_feat(NONTASK_POWER
))
849 sched_rt_avg_update(rq
, irq_delta
+ steal
);
853 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
855 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
856 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
860 * Make it appear like a SCHED_FIFO task, its something
861 * userspace knows about and won't get confused about.
863 * Also, it will make PI more or less work without too
864 * much confusion -- but then, stop work should not
865 * rely on PI working anyway.
867 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
869 stop
->sched_class
= &stop_sched_class
;
872 cpu_rq(cpu
)->stop
= stop
;
876 * Reset it back to a normal scheduling class so that
877 * it can die in pieces.
879 old_stop
->sched_class
= &rt_sched_class
;
884 * __normal_prio - return the priority that is based on the static prio
886 static inline int __normal_prio(struct task_struct
*p
)
888 return p
->static_prio
;
892 * Calculate the expected normal priority: i.e. priority
893 * without taking RT-inheritance into account. Might be
894 * boosted by interactivity modifiers. Changes upon fork,
895 * setprio syscalls, and whenever the interactivity
896 * estimator recalculates.
898 static inline int normal_prio(struct task_struct
*p
)
902 if (task_has_rt_policy(p
))
903 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
905 prio
= __normal_prio(p
);
910 * Calculate the current priority, i.e. the priority
911 * taken into account by the scheduler. This value might
912 * be boosted by RT tasks, or might be boosted by
913 * interactivity modifiers. Will be RT if the task got
914 * RT-boosted. If not then it returns p->normal_prio.
916 static int effective_prio(struct task_struct
*p
)
918 p
->normal_prio
= normal_prio(p
);
920 * If we are RT tasks or we were boosted to RT priority,
921 * keep the priority unchanged. Otherwise, update priority
922 * to the normal priority:
924 if (!rt_prio(p
->prio
))
925 return p
->normal_prio
;
930 * task_curr - is this task currently executing on a CPU?
931 * @p: the task in question.
933 * Return: 1 if the task is currently executing. 0 otherwise.
935 inline int task_curr(const struct task_struct
*p
)
937 return cpu_curr(task_cpu(p
)) == p
;
940 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
941 const struct sched_class
*prev_class
,
944 if (prev_class
!= p
->sched_class
) {
945 if (prev_class
->switched_from
)
946 prev_class
->switched_from(rq
, p
);
947 p
->sched_class
->switched_to(rq
, p
);
948 } else if (oldprio
!= p
->prio
)
949 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
952 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
954 const struct sched_class
*class;
956 if (p
->sched_class
== rq
->curr
->sched_class
) {
957 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
959 for_each_class(class) {
960 if (class == rq
->curr
->sched_class
)
962 if (class == p
->sched_class
) {
963 resched_task(rq
->curr
);
970 * A queue event has occurred, and we're going to schedule. In
971 * this case, we can save a useless back to back clock update.
973 if (rq
->curr
->on_rq
&& test_tsk_need_resched(rq
->curr
))
974 rq
->skip_clock_update
= 1;
978 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
980 #ifdef CONFIG_SCHED_DEBUG
982 * We should never call set_task_cpu() on a blocked task,
983 * ttwu() will sort out the placement.
985 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
986 !(task_preempt_count(p
) & PREEMPT_ACTIVE
));
988 #ifdef CONFIG_LOCKDEP
990 * The caller should hold either p->pi_lock or rq->lock, when changing
991 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
993 * sched_move_task() holds both and thus holding either pins the cgroup,
996 * Furthermore, all task_rq users should acquire both locks, see
999 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
1000 lockdep_is_held(&task_rq(p
)->lock
)));
1004 trace_sched_migrate_task(p
, new_cpu
);
1006 if (task_cpu(p
) != new_cpu
) {
1007 if (p
->sched_class
->migrate_task_rq
)
1008 p
->sched_class
->migrate_task_rq(p
, new_cpu
);
1009 p
->se
.nr_migrations
++;
1010 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, NULL
, 0);
1013 __set_task_cpu(p
, new_cpu
);
1016 static void __migrate_swap_task(struct task_struct
*p
, int cpu
)
1019 struct rq
*src_rq
, *dst_rq
;
1021 src_rq
= task_rq(p
);
1022 dst_rq
= cpu_rq(cpu
);
1024 deactivate_task(src_rq
, p
, 0);
1025 set_task_cpu(p
, cpu
);
1026 activate_task(dst_rq
, p
, 0);
1027 check_preempt_curr(dst_rq
, p
, 0);
1030 * Task isn't running anymore; make it appear like we migrated
1031 * it before it went to sleep. This means on wakeup we make the
1032 * previous cpu our targer instead of where it really is.
1038 struct migration_swap_arg
{
1039 struct task_struct
*src_task
, *dst_task
;
1040 int src_cpu
, dst_cpu
;
1043 static int migrate_swap_stop(void *data
)
1045 struct migration_swap_arg
*arg
= data
;
1046 struct rq
*src_rq
, *dst_rq
;
1049 src_rq
= cpu_rq(arg
->src_cpu
);
1050 dst_rq
= cpu_rq(arg
->dst_cpu
);
1052 double_raw_lock(&arg
->src_task
->pi_lock
,
1053 &arg
->dst_task
->pi_lock
);
1054 double_rq_lock(src_rq
, dst_rq
);
1055 if (task_cpu(arg
->dst_task
) != arg
->dst_cpu
)
1058 if (task_cpu(arg
->src_task
) != arg
->src_cpu
)
1061 if (!cpumask_test_cpu(arg
->dst_cpu
, tsk_cpus_allowed(arg
->src_task
)))
1064 if (!cpumask_test_cpu(arg
->src_cpu
, tsk_cpus_allowed(arg
->dst_task
)))
1067 __migrate_swap_task(arg
->src_task
, arg
->dst_cpu
);
1068 __migrate_swap_task(arg
->dst_task
, arg
->src_cpu
);
1073 double_rq_unlock(src_rq
, dst_rq
);
1074 raw_spin_unlock(&arg
->dst_task
->pi_lock
);
1075 raw_spin_unlock(&arg
->src_task
->pi_lock
);
1081 * Cross migrate two tasks
1083 int migrate_swap(struct task_struct
*cur
, struct task_struct
*p
)
1085 struct migration_swap_arg arg
;
1088 arg
= (struct migration_swap_arg
){
1090 .src_cpu
= task_cpu(cur
),
1092 .dst_cpu
= task_cpu(p
),
1095 if (arg
.src_cpu
== arg
.dst_cpu
)
1099 * These three tests are all lockless; this is OK since all of them
1100 * will be re-checked with proper locks held further down the line.
1102 if (!cpu_active(arg
.src_cpu
) || !cpu_active(arg
.dst_cpu
))
1105 if (!cpumask_test_cpu(arg
.dst_cpu
, tsk_cpus_allowed(arg
.src_task
)))
1108 if (!cpumask_test_cpu(arg
.src_cpu
, tsk_cpus_allowed(arg
.dst_task
)))
1111 ret
= stop_two_cpus(arg
.dst_cpu
, arg
.src_cpu
, migrate_swap_stop
, &arg
);
1117 struct migration_arg
{
1118 struct task_struct
*task
;
1122 static int migration_cpu_stop(void *data
);
1125 * wait_task_inactive - wait for a thread to unschedule.
1127 * If @match_state is nonzero, it's the @p->state value just checked and
1128 * not expected to change. If it changes, i.e. @p might have woken up,
1129 * then return zero. When we succeed in waiting for @p to be off its CPU,
1130 * we return a positive number (its total switch count). If a second call
1131 * a short while later returns the same number, the caller can be sure that
1132 * @p has remained unscheduled the whole time.
1134 * The caller must ensure that the task *will* unschedule sometime soon,
1135 * else this function might spin for a *long* time. This function can't
1136 * be called with interrupts off, or it may introduce deadlock with
1137 * smp_call_function() if an IPI is sent by the same process we are
1138 * waiting to become inactive.
1140 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1142 unsigned long flags
;
1149 * We do the initial early heuristics without holding
1150 * any task-queue locks at all. We'll only try to get
1151 * the runqueue lock when things look like they will
1157 * If the task is actively running on another CPU
1158 * still, just relax and busy-wait without holding
1161 * NOTE! Since we don't hold any locks, it's not
1162 * even sure that "rq" stays as the right runqueue!
1163 * But we don't care, since "task_running()" will
1164 * return false if the runqueue has changed and p
1165 * is actually now running somewhere else!
1167 while (task_running(rq
, p
)) {
1168 if (match_state
&& unlikely(p
->state
!= match_state
))
1174 * Ok, time to look more closely! We need the rq
1175 * lock now, to be *sure*. If we're wrong, we'll
1176 * just go back and repeat.
1178 rq
= task_rq_lock(p
, &flags
);
1179 trace_sched_wait_task(p
);
1180 running
= task_running(rq
, p
);
1183 if (!match_state
|| p
->state
== match_state
)
1184 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1185 task_rq_unlock(rq
, p
, &flags
);
1188 * If it changed from the expected state, bail out now.
1190 if (unlikely(!ncsw
))
1194 * Was it really running after all now that we
1195 * checked with the proper locks actually held?
1197 * Oops. Go back and try again..
1199 if (unlikely(running
)) {
1205 * It's not enough that it's not actively running,
1206 * it must be off the runqueue _entirely_, and not
1209 * So if it was still runnable (but just not actively
1210 * running right now), it's preempted, and we should
1211 * yield - it could be a while.
1213 if (unlikely(on_rq
)) {
1214 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1216 set_current_state(TASK_UNINTERRUPTIBLE
);
1217 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1222 * Ahh, all good. It wasn't running, and it wasn't
1223 * runnable, which means that it will never become
1224 * running in the future either. We're all done!
1233 * kick_process - kick a running thread to enter/exit the kernel
1234 * @p: the to-be-kicked thread
1236 * Cause a process which is running on another CPU to enter
1237 * kernel-mode, without any delay. (to get signals handled.)
1239 * NOTE: this function doesn't have to take the runqueue lock,
1240 * because all it wants to ensure is that the remote task enters
1241 * the kernel. If the IPI races and the task has been migrated
1242 * to another CPU then no harm is done and the purpose has been
1245 void kick_process(struct task_struct
*p
)
1251 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1252 smp_send_reschedule(cpu
);
1255 EXPORT_SYMBOL_GPL(kick_process
);
1256 #endif /* CONFIG_SMP */
1260 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1262 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1264 int nid
= cpu_to_node(cpu
);
1265 const struct cpumask
*nodemask
= NULL
;
1266 enum { cpuset
, possible
, fail
} state
= cpuset
;
1270 * If the node that the cpu is on has been offlined, cpu_to_node()
1271 * will return -1. There is no cpu on the node, and we should
1272 * select the cpu on the other node.
1275 nodemask
= cpumask_of_node(nid
);
1277 /* Look for allowed, online CPU in same node. */
1278 for_each_cpu(dest_cpu
, nodemask
) {
1279 if (!cpu_online(dest_cpu
))
1281 if (!cpu_active(dest_cpu
))
1283 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1289 /* Any allowed, online CPU? */
1290 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1291 if (!cpu_online(dest_cpu
))
1293 if (!cpu_active(dest_cpu
))
1300 /* No more Mr. Nice Guy. */
1301 cpuset_cpus_allowed_fallback(p
);
1306 do_set_cpus_allowed(p
, cpu_possible_mask
);
1317 if (state
!= cpuset
) {
1319 * Don't tell them about moving exiting tasks or
1320 * kernel threads (both mm NULL), since they never
1323 if (p
->mm
&& printk_ratelimit()) {
1324 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1325 task_pid_nr(p
), p
->comm
, cpu
);
1333 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1336 int select_task_rq(struct task_struct
*p
, int cpu
, int sd_flags
, int wake_flags
)
1338 cpu
= p
->sched_class
->select_task_rq(p
, cpu
, sd_flags
, wake_flags
);
1341 * In order not to call set_task_cpu() on a blocking task we need
1342 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1345 * Since this is common to all placement strategies, this lives here.
1347 * [ this allows ->select_task() to simply return task_cpu(p) and
1348 * not worry about this generic constraint ]
1350 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1352 cpu
= select_fallback_rq(task_cpu(p
), p
);
1357 static void update_avg(u64
*avg
, u64 sample
)
1359 s64 diff
= sample
- *avg
;
1365 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1367 #ifdef CONFIG_SCHEDSTATS
1368 struct rq
*rq
= this_rq();
1371 int this_cpu
= smp_processor_id();
1373 if (cpu
== this_cpu
) {
1374 schedstat_inc(rq
, ttwu_local
);
1375 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1377 struct sched_domain
*sd
;
1379 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1381 for_each_domain(this_cpu
, sd
) {
1382 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1383 schedstat_inc(sd
, ttwu_wake_remote
);
1390 if (wake_flags
& WF_MIGRATED
)
1391 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1393 #endif /* CONFIG_SMP */
1395 schedstat_inc(rq
, ttwu_count
);
1396 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1398 if (wake_flags
& WF_SYNC
)
1399 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1401 #endif /* CONFIG_SCHEDSTATS */
1404 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1406 activate_task(rq
, p
, en_flags
);
1409 /* if a worker is waking up, notify workqueue */
1410 if (p
->flags
& PF_WQ_WORKER
)
1411 wq_worker_waking_up(p
, cpu_of(rq
));
1415 * Mark the task runnable and perform wakeup-preemption.
1418 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1420 check_preempt_curr(rq
, p
, wake_flags
);
1421 trace_sched_wakeup(p
, true);
1423 p
->state
= TASK_RUNNING
;
1425 if (p
->sched_class
->task_woken
)
1426 p
->sched_class
->task_woken(rq
, p
);
1428 if (rq
->idle_stamp
) {
1429 u64 delta
= rq_clock(rq
) - rq
->idle_stamp
;
1430 u64 max
= 2*rq
->max_idle_balance_cost
;
1432 update_avg(&rq
->avg_idle
, delta
);
1434 if (rq
->avg_idle
> max
)
1443 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1446 if (p
->sched_contributes_to_load
)
1447 rq
->nr_uninterruptible
--;
1450 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1451 ttwu_do_wakeup(rq
, p
, wake_flags
);
1455 * Called in case the task @p isn't fully descheduled from its runqueue,
1456 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1457 * since all we need to do is flip p->state to TASK_RUNNING, since
1458 * the task is still ->on_rq.
1460 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1465 rq
= __task_rq_lock(p
);
1467 /* check_preempt_curr() may use rq clock */
1468 update_rq_clock(rq
);
1469 ttwu_do_wakeup(rq
, p
, wake_flags
);
1472 __task_rq_unlock(rq
);
1478 static void sched_ttwu_pending(void)
1480 struct rq
*rq
= this_rq();
1481 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1482 struct task_struct
*p
;
1484 raw_spin_lock(&rq
->lock
);
1487 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1488 llist
= llist_next(llist
);
1489 ttwu_do_activate(rq
, p
, 0);
1492 raw_spin_unlock(&rq
->lock
);
1495 void scheduler_ipi(void)
1498 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1499 * TIF_NEED_RESCHED remotely (for the first time) will also send
1502 if (tif_need_resched())
1503 set_preempt_need_resched();
1505 if (llist_empty(&this_rq()->wake_list
)
1506 && !tick_nohz_full_cpu(smp_processor_id())
1507 && !got_nohz_idle_kick())
1511 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1512 * traditionally all their work was done from the interrupt return
1513 * path. Now that we actually do some work, we need to make sure
1516 * Some archs already do call them, luckily irq_enter/exit nest
1519 * Arguably we should visit all archs and update all handlers,
1520 * however a fair share of IPIs are still resched only so this would
1521 * somewhat pessimize the simple resched case.
1524 tick_nohz_full_check();
1525 sched_ttwu_pending();
1528 * Check if someone kicked us for doing the nohz idle load balance.
1530 if (unlikely(got_nohz_idle_kick())) {
1531 this_rq()->idle_balance
= 1;
1532 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1537 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1539 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
))
1540 smp_send_reschedule(cpu
);
1543 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1545 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1547 #endif /* CONFIG_SMP */
1549 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1551 struct rq
*rq
= cpu_rq(cpu
);
1553 #if defined(CONFIG_SMP)
1554 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1555 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1556 ttwu_queue_remote(p
, cpu
);
1561 raw_spin_lock(&rq
->lock
);
1562 ttwu_do_activate(rq
, p
, 0);
1563 raw_spin_unlock(&rq
->lock
);
1567 * try_to_wake_up - wake up a thread
1568 * @p: the thread to be awakened
1569 * @state: the mask of task states that can be woken
1570 * @wake_flags: wake modifier flags (WF_*)
1572 * Put it on the run-queue if it's not already there. The "current"
1573 * thread is always on the run-queue (except when the actual
1574 * re-schedule is in progress), and as such you're allowed to do
1575 * the simpler "current->state = TASK_RUNNING" to mark yourself
1576 * runnable without the overhead of this.
1578 * Return: %true if @p was woken up, %false if it was already running.
1579 * or @state didn't match @p's state.
1582 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
1584 unsigned long flags
;
1585 int cpu
, success
= 0;
1588 * If we are going to wake up a thread waiting for CONDITION we
1589 * need to ensure that CONDITION=1 done by the caller can not be
1590 * reordered with p->state check below. This pairs with mb() in
1591 * set_current_state() the waiting thread does.
1593 smp_mb__before_spinlock();
1594 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1595 if (!(p
->state
& state
))
1598 success
= 1; /* we're going to change ->state */
1601 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
1606 * If the owning (remote) cpu is still in the middle of schedule() with
1607 * this task as prev, wait until its done referencing the task.
1612 * Pairs with the smp_wmb() in finish_lock_switch().
1616 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
1617 p
->state
= TASK_WAKING
;
1619 if (p
->sched_class
->task_waking
)
1620 p
->sched_class
->task_waking(p
);
1622 cpu
= select_task_rq(p
, p
->wake_cpu
, SD_BALANCE_WAKE
, wake_flags
);
1623 if (task_cpu(p
) != cpu
) {
1624 wake_flags
|= WF_MIGRATED
;
1625 set_task_cpu(p
, cpu
);
1627 #endif /* CONFIG_SMP */
1631 ttwu_stat(p
, cpu
, wake_flags
);
1633 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1639 * try_to_wake_up_local - try to wake up a local task with rq lock held
1640 * @p: the thread to be awakened
1642 * Put @p on the run-queue if it's not already there. The caller must
1643 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1646 static void try_to_wake_up_local(struct task_struct
*p
)
1648 struct rq
*rq
= task_rq(p
);
1650 if (WARN_ON_ONCE(rq
!= this_rq()) ||
1651 WARN_ON_ONCE(p
== current
))
1654 lockdep_assert_held(&rq
->lock
);
1656 if (!raw_spin_trylock(&p
->pi_lock
)) {
1657 raw_spin_unlock(&rq
->lock
);
1658 raw_spin_lock(&p
->pi_lock
);
1659 raw_spin_lock(&rq
->lock
);
1662 if (!(p
->state
& TASK_NORMAL
))
1666 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
1668 ttwu_do_wakeup(rq
, p
, 0);
1669 ttwu_stat(p
, smp_processor_id(), 0);
1671 raw_spin_unlock(&p
->pi_lock
);
1675 * wake_up_process - Wake up a specific process
1676 * @p: The process to be woken up.
1678 * Attempt to wake up the nominated process and move it to the set of runnable
1681 * Return: 1 if the process was woken up, 0 if it was already running.
1683 * It may be assumed that this function implies a write memory barrier before
1684 * changing the task state if and only if any tasks are woken up.
1686 int wake_up_process(struct task_struct
*p
)
1688 WARN_ON(task_is_stopped_or_traced(p
));
1689 return try_to_wake_up(p
, TASK_NORMAL
, 0);
1691 EXPORT_SYMBOL(wake_up_process
);
1693 int wake_up_state(struct task_struct
*p
, unsigned int state
)
1695 return try_to_wake_up(p
, state
, 0);
1699 * Perform scheduler related setup for a newly forked process p.
1700 * p is forked by current.
1702 * __sched_fork() is basic setup used by init_idle() too:
1704 static void __sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
1709 p
->se
.exec_start
= 0;
1710 p
->se
.sum_exec_runtime
= 0;
1711 p
->se
.prev_sum_exec_runtime
= 0;
1712 p
->se
.nr_migrations
= 0;
1714 INIT_LIST_HEAD(&p
->se
.group_node
);
1716 #ifdef CONFIG_SCHEDSTATS
1717 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
1720 INIT_LIST_HEAD(&p
->rt
.run_list
);
1722 #ifdef CONFIG_PREEMPT_NOTIFIERS
1723 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1726 #ifdef CONFIG_NUMA_BALANCING
1727 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
1728 p
->mm
->numa_next_scan
= jiffies
+ msecs_to_jiffies(sysctl_numa_balancing_scan_delay
);
1729 p
->mm
->numa_scan_seq
= 0;
1732 if (clone_flags
& CLONE_VM
)
1733 p
->numa_preferred_nid
= current
->numa_preferred_nid
;
1735 p
->numa_preferred_nid
= -1;
1737 p
->node_stamp
= 0ULL;
1738 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
1739 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
1740 p
->numa_work
.next
= &p
->numa_work
;
1741 p
->numa_faults
= NULL
;
1742 p
->numa_faults_buffer
= NULL
;
1744 INIT_LIST_HEAD(&p
->numa_entry
);
1745 p
->numa_group
= NULL
;
1746 #endif /* CONFIG_NUMA_BALANCING */
1749 #ifdef CONFIG_NUMA_BALANCING
1750 #ifdef CONFIG_SCHED_DEBUG
1751 void set_numabalancing_state(bool enabled
)
1754 sched_feat_set("NUMA");
1756 sched_feat_set("NO_NUMA");
1759 __read_mostly
bool numabalancing_enabled
;
1761 void set_numabalancing_state(bool enabled
)
1763 numabalancing_enabled
= enabled
;
1765 #endif /* CONFIG_SCHED_DEBUG */
1766 #endif /* CONFIG_NUMA_BALANCING */
1769 * fork()/clone()-time setup:
1771 void sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
1773 unsigned long flags
;
1774 int cpu
= get_cpu();
1776 __sched_fork(clone_flags
, p
);
1778 * We mark the process as running here. This guarantees that
1779 * nobody will actually run it, and a signal or other external
1780 * event cannot wake it up and insert it on the runqueue either.
1782 p
->state
= TASK_RUNNING
;
1785 * Make sure we do not leak PI boosting priority to the child.
1787 p
->prio
= current
->normal_prio
;
1790 * Revert to default priority/policy on fork if requested.
1792 if (unlikely(p
->sched_reset_on_fork
)) {
1793 if (task_has_rt_policy(p
)) {
1794 p
->policy
= SCHED_NORMAL
;
1795 p
->static_prio
= NICE_TO_PRIO(0);
1797 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
1798 p
->static_prio
= NICE_TO_PRIO(0);
1800 p
->prio
= p
->normal_prio
= __normal_prio(p
);
1804 * We don't need the reset flag anymore after the fork. It has
1805 * fulfilled its duty:
1807 p
->sched_reset_on_fork
= 0;
1810 if (!rt_prio(p
->prio
))
1811 p
->sched_class
= &fair_sched_class
;
1813 if (p
->sched_class
->task_fork
)
1814 p
->sched_class
->task_fork(p
);
1817 * The child is not yet in the pid-hash so no cgroup attach races,
1818 * and the cgroup is pinned to this child due to cgroup_fork()
1819 * is ran before sched_fork().
1821 * Silence PROVE_RCU.
1823 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1824 set_task_cpu(p
, cpu
);
1825 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1827 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1828 if (likely(sched_info_on()))
1829 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1831 #if defined(CONFIG_SMP)
1834 init_task_preempt_count(p
);
1836 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
1843 * wake_up_new_task - wake up a newly created task for the first time.
1845 * This function will do some initial scheduler statistics housekeeping
1846 * that must be done for every newly created context, then puts the task
1847 * on the runqueue and wakes it.
1849 void wake_up_new_task(struct task_struct
*p
)
1851 unsigned long flags
;
1854 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1857 * Fork balancing, do it here and not earlier because:
1858 * - cpus_allowed can change in the fork path
1859 * - any previously selected cpu might disappear through hotplug
1861 set_task_cpu(p
, select_task_rq(p
, task_cpu(p
), SD_BALANCE_FORK
, 0));
1864 /* Initialize new task's runnable average */
1865 init_task_runnable_average(p
);
1866 rq
= __task_rq_lock(p
);
1867 activate_task(rq
, p
, 0);
1869 trace_sched_wakeup_new(p
, true);
1870 check_preempt_curr(rq
, p
, WF_FORK
);
1872 if (p
->sched_class
->task_woken
)
1873 p
->sched_class
->task_woken(rq
, p
);
1875 task_rq_unlock(rq
, p
, &flags
);
1878 #ifdef CONFIG_PREEMPT_NOTIFIERS
1881 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1882 * @notifier: notifier struct to register
1884 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1886 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1888 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1891 * preempt_notifier_unregister - no longer interested in preemption notifications
1892 * @notifier: notifier struct to unregister
1894 * This is safe to call from within a preemption notifier.
1896 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1898 hlist_del(¬ifier
->link
);
1900 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1902 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1904 struct preempt_notifier
*notifier
;
1906 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1907 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1911 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1912 struct task_struct
*next
)
1914 struct preempt_notifier
*notifier
;
1916 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1917 notifier
->ops
->sched_out(notifier
, next
);
1920 #else /* !CONFIG_PREEMPT_NOTIFIERS */
1922 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1927 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1928 struct task_struct
*next
)
1932 #endif /* CONFIG_PREEMPT_NOTIFIERS */
1935 * prepare_task_switch - prepare to switch tasks
1936 * @rq: the runqueue preparing to switch
1937 * @prev: the current task that is being switched out
1938 * @next: the task we are going to switch to.
1940 * This is called with the rq lock held and interrupts off. It must
1941 * be paired with a subsequent finish_task_switch after the context
1944 * prepare_task_switch sets up locking and calls architecture specific
1948 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1949 struct task_struct
*next
)
1951 trace_sched_switch(prev
, next
);
1952 sched_info_switch(rq
, prev
, next
);
1953 perf_event_task_sched_out(prev
, next
);
1954 fire_sched_out_preempt_notifiers(prev
, next
);
1955 prepare_lock_switch(rq
, next
);
1956 prepare_arch_switch(next
);
1960 * finish_task_switch - clean up after a task-switch
1961 * @rq: runqueue associated with task-switch
1962 * @prev: the thread we just switched away from.
1964 * finish_task_switch must be called after the context switch, paired
1965 * with a prepare_task_switch call before the context switch.
1966 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1967 * and do any other architecture-specific cleanup actions.
1969 * Note that we may have delayed dropping an mm in context_switch(). If
1970 * so, we finish that here outside of the runqueue lock. (Doing it
1971 * with the lock held can cause deadlocks; see schedule() for
1974 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1975 __releases(rq
->lock
)
1977 struct mm_struct
*mm
= rq
->prev_mm
;
1983 * A task struct has one reference for the use as "current".
1984 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1985 * schedule one last time. The schedule call will never return, and
1986 * the scheduled task must drop that reference.
1987 * The test for TASK_DEAD must occur while the runqueue locks are
1988 * still held, otherwise prev could be scheduled on another cpu, die
1989 * there before we look at prev->state, and then the reference would
1991 * Manfred Spraul <manfred@colorfullife.com>
1993 prev_state
= prev
->state
;
1994 vtime_task_switch(prev
);
1995 finish_arch_switch(prev
);
1996 perf_event_task_sched_in(prev
, current
);
1997 finish_lock_switch(rq
, prev
);
1998 finish_arch_post_lock_switch();
2000 fire_sched_in_preempt_notifiers(current
);
2003 if (unlikely(prev_state
== TASK_DEAD
)) {
2004 task_numa_free(prev
);
2007 * Remove function-return probe instances associated with this
2008 * task and put them back on the free list.
2010 kprobe_flush_task(prev
);
2011 put_task_struct(prev
);
2014 tick_nohz_task_switch(current
);
2019 /* assumes rq->lock is held */
2020 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*prev
)
2022 if (prev
->sched_class
->pre_schedule
)
2023 prev
->sched_class
->pre_schedule(rq
, prev
);
2026 /* rq->lock is NOT held, but preemption is disabled */
2027 static inline void post_schedule(struct rq
*rq
)
2029 if (rq
->post_schedule
) {
2030 unsigned long flags
;
2032 raw_spin_lock_irqsave(&rq
->lock
, flags
);
2033 if (rq
->curr
->sched_class
->post_schedule
)
2034 rq
->curr
->sched_class
->post_schedule(rq
);
2035 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
2037 rq
->post_schedule
= 0;
2043 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*p
)
2047 static inline void post_schedule(struct rq
*rq
)
2054 * schedule_tail - first thing a freshly forked thread must call.
2055 * @prev: the thread we just switched away from.
2057 asmlinkage
void schedule_tail(struct task_struct
*prev
)
2058 __releases(rq
->lock
)
2060 struct rq
*rq
= this_rq();
2062 finish_task_switch(rq
, prev
);
2065 * FIXME: do we need to worry about rq being invalidated by the
2070 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2071 /* In this case, finish_task_switch does not reenable preemption */
2074 if (current
->set_child_tid
)
2075 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2079 * context_switch - switch to the new MM and the new
2080 * thread's register state.
2083 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2084 struct task_struct
*next
)
2086 struct mm_struct
*mm
, *oldmm
;
2088 prepare_task_switch(rq
, prev
, next
);
2091 oldmm
= prev
->active_mm
;
2093 * For paravirt, this is coupled with an exit in switch_to to
2094 * combine the page table reload and the switch backend into
2097 arch_start_context_switch(prev
);
2100 next
->active_mm
= oldmm
;
2101 atomic_inc(&oldmm
->mm_count
);
2102 enter_lazy_tlb(oldmm
, next
);
2104 switch_mm(oldmm
, mm
, next
);
2107 prev
->active_mm
= NULL
;
2108 rq
->prev_mm
= oldmm
;
2111 * Since the runqueue lock will be released by the next
2112 * task (which is an invalid locking op but in the case
2113 * of the scheduler it's an obvious special-case), so we
2114 * do an early lockdep release here:
2116 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2117 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2120 context_tracking_task_switch(prev
, next
);
2121 /* Here we just switch the register state and the stack. */
2122 switch_to(prev
, next
, prev
);
2126 * this_rq must be evaluated again because prev may have moved
2127 * CPUs since it called schedule(), thus the 'rq' on its stack
2128 * frame will be invalid.
2130 finish_task_switch(this_rq(), prev
);
2134 * nr_running and nr_context_switches:
2136 * externally visible scheduler statistics: current number of runnable
2137 * threads, total number of context switches performed since bootup.
2139 unsigned long nr_running(void)
2141 unsigned long i
, sum
= 0;
2143 for_each_online_cpu(i
)
2144 sum
+= cpu_rq(i
)->nr_running
;
2149 unsigned long long nr_context_switches(void)
2152 unsigned long long sum
= 0;
2154 for_each_possible_cpu(i
)
2155 sum
+= cpu_rq(i
)->nr_switches
;
2160 unsigned long nr_iowait(void)
2162 unsigned long i
, sum
= 0;
2164 for_each_possible_cpu(i
)
2165 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2170 unsigned long nr_iowait_cpu(int cpu
)
2172 struct rq
*this = cpu_rq(cpu
);
2173 return atomic_read(&this->nr_iowait
);
2179 * sched_exec - execve() is a valuable balancing opportunity, because at
2180 * this point the task has the smallest effective memory and cache footprint.
2182 void sched_exec(void)
2184 struct task_struct
*p
= current
;
2185 unsigned long flags
;
2188 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2189 dest_cpu
= p
->sched_class
->select_task_rq(p
, task_cpu(p
), SD_BALANCE_EXEC
, 0);
2190 if (dest_cpu
== smp_processor_id())
2193 if (likely(cpu_active(dest_cpu
))) {
2194 struct migration_arg arg
= { p
, dest_cpu
};
2196 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2197 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2201 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2206 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2207 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2209 EXPORT_PER_CPU_SYMBOL(kstat
);
2210 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2213 * Return any ns on the sched_clock that have not yet been accounted in
2214 * @p in case that task is currently running.
2216 * Called with task_rq_lock() held on @rq.
2218 static u64
do_task_delta_exec(struct task_struct
*p
, struct rq
*rq
)
2222 if (task_current(rq
, p
)) {
2223 update_rq_clock(rq
);
2224 ns
= rq_clock_task(rq
) - p
->se
.exec_start
;
2232 unsigned long long task_delta_exec(struct task_struct
*p
)
2234 unsigned long flags
;
2238 rq
= task_rq_lock(p
, &flags
);
2239 ns
= do_task_delta_exec(p
, rq
);
2240 task_rq_unlock(rq
, p
, &flags
);
2246 * Return accounted runtime for the task.
2247 * In case the task is currently running, return the runtime plus current's
2248 * pending runtime that have not been accounted yet.
2250 unsigned long long task_sched_runtime(struct task_struct
*p
)
2252 unsigned long flags
;
2256 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2258 * 64-bit doesn't need locks to atomically read a 64bit value.
2259 * So we have a optimization chance when the task's delta_exec is 0.
2260 * Reading ->on_cpu is racy, but this is ok.
2262 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2263 * If we race with it entering cpu, unaccounted time is 0. This is
2264 * indistinguishable from the read occurring a few cycles earlier.
2267 return p
->se
.sum_exec_runtime
;
2270 rq
= task_rq_lock(p
, &flags
);
2271 ns
= p
->se
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
2272 task_rq_unlock(rq
, p
, &flags
);
2278 * This function gets called by the timer code, with HZ frequency.
2279 * We call it with interrupts disabled.
2281 void scheduler_tick(void)
2283 int cpu
= smp_processor_id();
2284 struct rq
*rq
= cpu_rq(cpu
);
2285 struct task_struct
*curr
= rq
->curr
;
2289 raw_spin_lock(&rq
->lock
);
2290 update_rq_clock(rq
);
2291 curr
->sched_class
->task_tick(rq
, curr
, 0);
2292 update_cpu_load_active(rq
);
2293 raw_spin_unlock(&rq
->lock
);
2295 perf_event_task_tick();
2298 rq
->idle_balance
= idle_cpu(cpu
);
2299 trigger_load_balance(rq
, cpu
);
2301 rq_last_tick_reset(rq
);
2304 #ifdef CONFIG_NO_HZ_FULL
2306 * scheduler_tick_max_deferment
2308 * Keep at least one tick per second when a single
2309 * active task is running because the scheduler doesn't
2310 * yet completely support full dynticks environment.
2312 * This makes sure that uptime, CFS vruntime, load
2313 * balancing, etc... continue to move forward, even
2314 * with a very low granularity.
2316 * Return: Maximum deferment in nanoseconds.
2318 u64
scheduler_tick_max_deferment(void)
2320 struct rq
*rq
= this_rq();
2321 unsigned long next
, now
= ACCESS_ONCE(jiffies
);
2323 next
= rq
->last_sched_tick
+ HZ
;
2325 if (time_before_eq(next
, now
))
2328 return jiffies_to_usecs(next
- now
) * NSEC_PER_USEC
;
2332 notrace
unsigned long get_parent_ip(unsigned long addr
)
2334 if (in_lock_functions(addr
)) {
2335 addr
= CALLER_ADDR2
;
2336 if (in_lock_functions(addr
))
2337 addr
= CALLER_ADDR3
;
2342 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2343 defined(CONFIG_PREEMPT_TRACER))
2345 void __kprobes
preempt_count_add(int val
)
2347 #ifdef CONFIG_DEBUG_PREEMPT
2351 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2354 __preempt_count_add(val
);
2355 #ifdef CONFIG_DEBUG_PREEMPT
2357 * Spinlock count overflowing soon?
2359 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
2362 if (preempt_count() == val
)
2363 trace_preempt_off(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2365 EXPORT_SYMBOL(preempt_count_add
);
2367 void __kprobes
preempt_count_sub(int val
)
2369 #ifdef CONFIG_DEBUG_PREEMPT
2373 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
2376 * Is the spinlock portion underflowing?
2378 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
2379 !(preempt_count() & PREEMPT_MASK
)))
2383 if (preempt_count() == val
)
2384 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2385 __preempt_count_sub(val
);
2387 EXPORT_SYMBOL(preempt_count_sub
);
2392 * Print scheduling while atomic bug:
2394 static noinline
void __schedule_bug(struct task_struct
*prev
)
2396 if (oops_in_progress
)
2399 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
2400 prev
->comm
, prev
->pid
, preempt_count());
2402 debug_show_held_locks(prev
);
2404 if (irqs_disabled())
2405 print_irqtrace_events(prev
);
2407 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
2411 * Various schedule()-time debugging checks and statistics:
2413 static inline void schedule_debug(struct task_struct
*prev
)
2416 * Test if we are atomic. Since do_exit() needs to call into
2417 * schedule() atomically, we ignore that path for now.
2418 * Otherwise, whine if we are scheduling when we should not be.
2420 if (unlikely(in_atomic_preempt_off() && !prev
->exit_state
))
2421 __schedule_bug(prev
);
2424 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2426 schedstat_inc(this_rq(), sched_count
);
2429 static void put_prev_task(struct rq
*rq
, struct task_struct
*prev
)
2431 if (prev
->on_rq
|| rq
->skip_clock_update
< 0)
2432 update_rq_clock(rq
);
2433 prev
->sched_class
->put_prev_task(rq
, prev
);
2437 * Pick up the highest-prio task:
2439 static inline struct task_struct
*
2440 pick_next_task(struct rq
*rq
)
2442 const struct sched_class
*class;
2443 struct task_struct
*p
;
2446 * Optimization: we know that if all tasks are in
2447 * the fair class we can call that function directly:
2449 if (likely(rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
2450 p
= fair_sched_class
.pick_next_task(rq
);
2455 for_each_class(class) {
2456 p
= class->pick_next_task(rq
);
2461 BUG(); /* the idle class will always have a runnable task */
2465 * __schedule() is the main scheduler function.
2467 * The main means of driving the scheduler and thus entering this function are:
2469 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2471 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2472 * paths. For example, see arch/x86/entry_64.S.
2474 * To drive preemption between tasks, the scheduler sets the flag in timer
2475 * interrupt handler scheduler_tick().
2477 * 3. Wakeups don't really cause entry into schedule(). They add a
2478 * task to the run-queue and that's it.
2480 * Now, if the new task added to the run-queue preempts the current
2481 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2482 * called on the nearest possible occasion:
2484 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2486 * - in syscall or exception context, at the next outmost
2487 * preempt_enable(). (this might be as soon as the wake_up()'s
2490 * - in IRQ context, return from interrupt-handler to
2491 * preemptible context
2493 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2496 * - cond_resched() call
2497 * - explicit schedule() call
2498 * - return from syscall or exception to user-space
2499 * - return from interrupt-handler to user-space
2501 static void __sched
__schedule(void)
2503 struct task_struct
*prev
, *next
;
2504 unsigned long *switch_count
;
2510 cpu
= smp_processor_id();
2512 rcu_note_context_switch(cpu
);
2515 schedule_debug(prev
);
2517 if (sched_feat(HRTICK
))
2521 * Make sure that signal_pending_state()->signal_pending() below
2522 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2523 * done by the caller to avoid the race with signal_wake_up().
2525 smp_mb__before_spinlock();
2526 raw_spin_lock_irq(&rq
->lock
);
2528 switch_count
= &prev
->nivcsw
;
2529 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2530 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
2531 prev
->state
= TASK_RUNNING
;
2533 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
2537 * If a worker went to sleep, notify and ask workqueue
2538 * whether it wants to wake up a task to maintain
2541 if (prev
->flags
& PF_WQ_WORKER
) {
2542 struct task_struct
*to_wakeup
;
2544 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
2546 try_to_wake_up_local(to_wakeup
);
2549 switch_count
= &prev
->nvcsw
;
2552 pre_schedule(rq
, prev
);
2554 if (unlikely(!rq
->nr_running
))
2555 idle_balance(cpu
, rq
);
2557 put_prev_task(rq
, prev
);
2558 next
= pick_next_task(rq
);
2559 clear_tsk_need_resched(prev
);
2560 clear_preempt_need_resched();
2561 rq
->skip_clock_update
= 0;
2563 if (likely(prev
!= next
)) {
2568 context_switch(rq
, prev
, next
); /* unlocks the rq */
2570 * The context switch have flipped the stack from under us
2571 * and restored the local variables which were saved when
2572 * this task called schedule() in the past. prev == current
2573 * is still correct, but it can be moved to another cpu/rq.
2575 cpu
= smp_processor_id();
2578 raw_spin_unlock_irq(&rq
->lock
);
2582 sched_preempt_enable_no_resched();
2587 static inline void sched_submit_work(struct task_struct
*tsk
)
2589 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
2592 * If we are going to sleep and we have plugged IO queued,
2593 * make sure to submit it to avoid deadlocks.
2595 if (blk_needs_flush_plug(tsk
))
2596 blk_schedule_flush_plug(tsk
);
2599 asmlinkage
void __sched
schedule(void)
2601 struct task_struct
*tsk
= current
;
2603 sched_submit_work(tsk
);
2606 EXPORT_SYMBOL(schedule
);
2608 #ifdef CONFIG_CONTEXT_TRACKING
2609 asmlinkage
void __sched
schedule_user(void)
2612 * If we come here after a random call to set_need_resched(),
2613 * or we have been woken up remotely but the IPI has not yet arrived,
2614 * we haven't yet exited the RCU idle mode. Do it here manually until
2615 * we find a better solution.
2624 * schedule_preempt_disabled - called with preemption disabled
2626 * Returns with preemption disabled. Note: preempt_count must be 1
2628 void __sched
schedule_preempt_disabled(void)
2630 sched_preempt_enable_no_resched();
2635 #ifdef CONFIG_PREEMPT
2637 * this is the entry point to schedule() from in-kernel preemption
2638 * off of preempt_enable. Kernel preemptions off return from interrupt
2639 * occur there and call schedule directly.
2641 asmlinkage
void __sched notrace
preempt_schedule(void)
2644 * If there is a non-zero preempt_count or interrupts are disabled,
2645 * we do not want to preempt the current task. Just return..
2647 if (likely(!preemptible()))
2651 __preempt_count_add(PREEMPT_ACTIVE
);
2653 __preempt_count_sub(PREEMPT_ACTIVE
);
2656 * Check again in case we missed a preemption opportunity
2657 * between schedule and now.
2660 } while (need_resched());
2662 EXPORT_SYMBOL(preempt_schedule
);
2663 #endif /* CONFIG_PREEMPT */
2666 * this is the entry point to schedule() from kernel preemption
2667 * off of irq context.
2668 * Note, that this is called and return with irqs disabled. This will
2669 * protect us against recursive calling from irq.
2671 asmlinkage
void __sched
preempt_schedule_irq(void)
2673 enum ctx_state prev_state
;
2675 /* Catch callers which need to be fixed */
2676 BUG_ON(preempt_count() || !irqs_disabled());
2678 prev_state
= exception_enter();
2681 __preempt_count_add(PREEMPT_ACTIVE
);
2684 local_irq_disable();
2685 __preempt_count_sub(PREEMPT_ACTIVE
);
2688 * Check again in case we missed a preemption opportunity
2689 * between schedule and now.
2692 } while (need_resched());
2694 exception_exit(prev_state
);
2697 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
2700 return try_to_wake_up(curr
->private, mode
, wake_flags
);
2702 EXPORT_SYMBOL(default_wake_function
);
2705 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
2707 unsigned long flags
;
2710 init_waitqueue_entry(&wait
, current
);
2712 __set_current_state(state
);
2714 spin_lock_irqsave(&q
->lock
, flags
);
2715 __add_wait_queue(q
, &wait
);
2716 spin_unlock(&q
->lock
);
2717 timeout
= schedule_timeout(timeout
);
2718 spin_lock_irq(&q
->lock
);
2719 __remove_wait_queue(q
, &wait
);
2720 spin_unlock_irqrestore(&q
->lock
, flags
);
2725 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
2727 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2729 EXPORT_SYMBOL(interruptible_sleep_on
);
2732 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
2734 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
2736 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
2738 void __sched
sleep_on(wait_queue_head_t
*q
)
2740 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2742 EXPORT_SYMBOL(sleep_on
);
2744 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
2746 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
2748 EXPORT_SYMBOL(sleep_on_timeout
);
2750 #ifdef CONFIG_RT_MUTEXES
2753 * rt_mutex_setprio - set the current priority of a task
2755 * @prio: prio value (kernel-internal form)
2757 * This function changes the 'effective' priority of a task. It does
2758 * not touch ->normal_prio like __setscheduler().
2760 * Used by the rt_mutex code to implement priority inheritance logic.
2762 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
2764 int oldprio
, on_rq
, running
;
2766 const struct sched_class
*prev_class
;
2768 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
2770 rq
= __task_rq_lock(p
);
2773 * Idle task boosting is a nono in general. There is one
2774 * exception, when PREEMPT_RT and NOHZ is active:
2776 * The idle task calls get_next_timer_interrupt() and holds
2777 * the timer wheel base->lock on the CPU and another CPU wants
2778 * to access the timer (probably to cancel it). We can safely
2779 * ignore the boosting request, as the idle CPU runs this code
2780 * with interrupts disabled and will complete the lock
2781 * protected section without being interrupted. So there is no
2782 * real need to boost.
2784 if (unlikely(p
== rq
->idle
)) {
2785 WARN_ON(p
!= rq
->curr
);
2786 WARN_ON(p
->pi_blocked_on
);
2790 trace_sched_pi_setprio(p
, prio
);
2792 prev_class
= p
->sched_class
;
2794 running
= task_current(rq
, p
);
2796 dequeue_task(rq
, p
, 0);
2798 p
->sched_class
->put_prev_task(rq
, p
);
2801 p
->sched_class
= &rt_sched_class
;
2803 p
->sched_class
= &fair_sched_class
;
2808 p
->sched_class
->set_curr_task(rq
);
2810 enqueue_task(rq
, p
, oldprio
< prio
? ENQUEUE_HEAD
: 0);
2812 check_class_changed(rq
, p
, prev_class
, oldprio
);
2814 __task_rq_unlock(rq
);
2817 void set_user_nice(struct task_struct
*p
, long nice
)
2819 int old_prio
, delta
, on_rq
;
2820 unsigned long flags
;
2823 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
2826 * We have to be careful, if called from sys_setpriority(),
2827 * the task might be in the middle of scheduling on another CPU.
2829 rq
= task_rq_lock(p
, &flags
);
2831 * The RT priorities are set via sched_setscheduler(), but we still
2832 * allow the 'normal' nice value to be set - but as expected
2833 * it wont have any effect on scheduling until the task is
2834 * SCHED_FIFO/SCHED_RR:
2836 if (task_has_rt_policy(p
)) {
2837 p
->static_prio
= NICE_TO_PRIO(nice
);
2842 dequeue_task(rq
, p
, 0);
2844 p
->static_prio
= NICE_TO_PRIO(nice
);
2847 p
->prio
= effective_prio(p
);
2848 delta
= p
->prio
- old_prio
;
2851 enqueue_task(rq
, p
, 0);
2853 * If the task increased its priority or is running and
2854 * lowered its priority, then reschedule its CPU:
2856 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
2857 resched_task(rq
->curr
);
2860 task_rq_unlock(rq
, p
, &flags
);
2862 EXPORT_SYMBOL(set_user_nice
);
2865 * can_nice - check if a task can reduce its nice value
2869 int can_nice(const struct task_struct
*p
, const int nice
)
2871 /* convert nice value [19,-20] to rlimit style value [1,40] */
2872 int nice_rlim
= 20 - nice
;
2874 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
2875 capable(CAP_SYS_NICE
));
2878 #ifdef __ARCH_WANT_SYS_NICE
2881 * sys_nice - change the priority of the current process.
2882 * @increment: priority increment
2884 * sys_setpriority is a more generic, but much slower function that
2885 * does similar things.
2887 SYSCALL_DEFINE1(nice
, int, increment
)
2892 * Setpriority might change our priority at the same moment.
2893 * We don't have to worry. Conceptually one call occurs first
2894 * and we have a single winner.
2896 if (increment
< -40)
2901 nice
= TASK_NICE(current
) + increment
;
2907 if (increment
< 0 && !can_nice(current
, nice
))
2910 retval
= security_task_setnice(current
, nice
);
2914 set_user_nice(current
, nice
);
2921 * task_prio - return the priority value of a given task.
2922 * @p: the task in question.
2924 * Return: The priority value as seen by users in /proc.
2925 * RT tasks are offset by -200. Normal tasks are centered
2926 * around 0, value goes from -16 to +15.
2928 int task_prio(const struct task_struct
*p
)
2930 return p
->prio
- MAX_RT_PRIO
;
2934 * task_nice - return the nice value of a given task.
2935 * @p: the task in question.
2937 * Return: The nice value [ -20 ... 0 ... 19 ].
2939 int task_nice(const struct task_struct
*p
)
2941 return TASK_NICE(p
);
2943 EXPORT_SYMBOL(task_nice
);
2946 * idle_cpu - is a given cpu idle currently?
2947 * @cpu: the processor in question.
2949 * Return: 1 if the CPU is currently idle. 0 otherwise.
2951 int idle_cpu(int cpu
)
2953 struct rq
*rq
= cpu_rq(cpu
);
2955 if (rq
->curr
!= rq
->idle
)
2962 if (!llist_empty(&rq
->wake_list
))
2970 * idle_task - return the idle task for a given cpu.
2971 * @cpu: the processor in question.
2973 * Return: The idle task for the cpu @cpu.
2975 struct task_struct
*idle_task(int cpu
)
2977 return cpu_rq(cpu
)->idle
;
2981 * find_process_by_pid - find a process with a matching PID value.
2982 * @pid: the pid in question.
2984 * The task of @pid, if found. %NULL otherwise.
2986 static struct task_struct
*find_process_by_pid(pid_t pid
)
2988 return pid
? find_task_by_vpid(pid
) : current
;
2991 /* Actually do priority change: must hold rq lock. */
2993 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
2996 p
->rt_priority
= prio
;
2997 p
->normal_prio
= normal_prio(p
);
2998 /* we are holding p->pi_lock already */
2999 p
->prio
= rt_mutex_getprio(p
);
3000 if (rt_prio(p
->prio
))
3001 p
->sched_class
= &rt_sched_class
;
3003 p
->sched_class
= &fair_sched_class
;
3008 * check the target process has a UID that matches the current process's
3010 static bool check_same_owner(struct task_struct
*p
)
3012 const struct cred
*cred
= current_cred(), *pcred
;
3016 pcred
= __task_cred(p
);
3017 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3018 uid_eq(cred
->euid
, pcred
->uid
));
3023 static int __sched_setscheduler(struct task_struct
*p
, int policy
,
3024 const struct sched_param
*param
, bool user
)
3026 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
3027 unsigned long flags
;
3028 const struct sched_class
*prev_class
;
3032 /* may grab non-irq protected spin_locks */
3033 BUG_ON(in_interrupt());
3035 /* double check policy once rq lock held */
3037 reset_on_fork
= p
->sched_reset_on_fork
;
3038 policy
= oldpolicy
= p
->policy
;
3040 reset_on_fork
= !!(policy
& SCHED_RESET_ON_FORK
);
3041 policy
&= ~SCHED_RESET_ON_FORK
;
3043 if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3044 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
3045 policy
!= SCHED_IDLE
)
3050 * Valid priorities for SCHED_FIFO and SCHED_RR are
3051 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3052 * SCHED_BATCH and SCHED_IDLE is 0.
3054 if (param
->sched_priority
< 0 ||
3055 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3056 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3058 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
3062 * Allow unprivileged RT tasks to decrease priority:
3064 if (user
&& !capable(CAP_SYS_NICE
)) {
3065 if (rt_policy(policy
)) {
3066 unsigned long rlim_rtprio
=
3067 task_rlimit(p
, RLIMIT_RTPRIO
);
3069 /* can't set/change the rt policy */
3070 if (policy
!= p
->policy
&& !rlim_rtprio
)
3073 /* can't increase priority */
3074 if (param
->sched_priority
> p
->rt_priority
&&
3075 param
->sched_priority
> rlim_rtprio
)
3080 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3081 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3083 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
3084 if (!can_nice(p
, TASK_NICE(p
)))
3088 /* can't change other user's priorities */
3089 if (!check_same_owner(p
))
3092 /* Normal users shall not reset the sched_reset_on_fork flag */
3093 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3098 retval
= security_task_setscheduler(p
);
3104 * make sure no PI-waiters arrive (or leave) while we are
3105 * changing the priority of the task:
3107 * To be able to change p->policy safely, the appropriate
3108 * runqueue lock must be held.
3110 rq
= task_rq_lock(p
, &flags
);
3113 * Changing the policy of the stop threads its a very bad idea
3115 if (p
== rq
->stop
) {
3116 task_rq_unlock(rq
, p
, &flags
);
3121 * If not changing anything there's no need to proceed further:
3123 if (unlikely(policy
== p
->policy
&& (!rt_policy(policy
) ||
3124 param
->sched_priority
== p
->rt_priority
))) {
3125 task_rq_unlock(rq
, p
, &flags
);
3129 #ifdef CONFIG_RT_GROUP_SCHED
3132 * Do not allow realtime tasks into groups that have no runtime
3135 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
3136 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
3137 !task_group_is_autogroup(task_group(p
))) {
3138 task_rq_unlock(rq
, p
, &flags
);
3144 /* recheck policy now with rq lock held */
3145 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3146 policy
= oldpolicy
= -1;
3147 task_rq_unlock(rq
, p
, &flags
);
3151 running
= task_current(rq
, p
);
3153 dequeue_task(rq
, p
, 0);
3155 p
->sched_class
->put_prev_task(rq
, p
);
3157 p
->sched_reset_on_fork
= reset_on_fork
;
3160 prev_class
= p
->sched_class
;
3161 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
3164 p
->sched_class
->set_curr_task(rq
);
3166 enqueue_task(rq
, p
, 0);
3168 check_class_changed(rq
, p
, prev_class
, oldprio
);
3169 task_rq_unlock(rq
, p
, &flags
);
3171 rt_mutex_adjust_pi(p
);
3177 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3178 * @p: the task in question.
3179 * @policy: new policy.
3180 * @param: structure containing the new RT priority.
3182 * Return: 0 on success. An error code otherwise.
3184 * NOTE that the task may be already dead.
3186 int sched_setscheduler(struct task_struct
*p
, int policy
,
3187 const struct sched_param
*param
)
3189 return __sched_setscheduler(p
, policy
, param
, true);
3191 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3194 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3195 * @p: the task in question.
3196 * @policy: new policy.
3197 * @param: structure containing the new RT priority.
3199 * Just like sched_setscheduler, only don't bother checking if the
3200 * current context has permission. For example, this is needed in
3201 * stop_machine(): we create temporary high priority worker threads,
3202 * but our caller might not have that capability.
3204 * Return: 0 on success. An error code otherwise.
3206 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
3207 const struct sched_param
*param
)
3209 return __sched_setscheduler(p
, policy
, param
, false);
3213 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3215 struct sched_param lparam
;
3216 struct task_struct
*p
;
3219 if (!param
|| pid
< 0)
3221 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3226 p
= find_process_by_pid(pid
);
3228 retval
= sched_setscheduler(p
, policy
, &lparam
);
3235 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3236 * @pid: the pid in question.
3237 * @policy: new policy.
3238 * @param: structure containing the new RT priority.
3240 * Return: 0 on success. An error code otherwise.
3242 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
3243 struct sched_param __user
*, param
)
3245 /* negative values for policy are not valid */
3249 return do_sched_setscheduler(pid
, policy
, param
);
3253 * sys_sched_setparam - set/change the RT priority of a thread
3254 * @pid: the pid in question.
3255 * @param: structure containing the new RT priority.
3257 * Return: 0 on success. An error code otherwise.
3259 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
3261 return do_sched_setscheduler(pid
, -1, param
);
3265 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3266 * @pid: the pid in question.
3268 * Return: On success, the policy of the thread. Otherwise, a negative error
3271 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
3273 struct task_struct
*p
;
3281 p
= find_process_by_pid(pid
);
3283 retval
= security_task_getscheduler(p
);
3286 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
3293 * sys_sched_getparam - get the RT priority of a thread
3294 * @pid: the pid in question.
3295 * @param: structure containing the RT priority.
3297 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3300 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
3302 struct sched_param lp
;
3303 struct task_struct
*p
;
3306 if (!param
|| pid
< 0)
3310 p
= find_process_by_pid(pid
);
3315 retval
= security_task_getscheduler(p
);
3319 lp
.sched_priority
= p
->rt_priority
;
3323 * This one might sleep, we cannot do it with a spinlock held ...
3325 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3334 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
3336 cpumask_var_t cpus_allowed
, new_mask
;
3337 struct task_struct
*p
;
3342 p
= find_process_by_pid(pid
);
3348 /* Prevent p going away */
3352 if (p
->flags
& PF_NO_SETAFFINITY
) {
3356 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
3360 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
3362 goto out_free_cpus_allowed
;
3365 if (!check_same_owner(p
)) {
3367 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
3374 retval
= security_task_setscheduler(p
);
3378 cpuset_cpus_allowed(p
, cpus_allowed
);
3379 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
3381 retval
= set_cpus_allowed_ptr(p
, new_mask
);
3384 cpuset_cpus_allowed(p
, cpus_allowed
);
3385 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
3387 * We must have raced with a concurrent cpuset
3388 * update. Just reset the cpus_allowed to the
3389 * cpuset's cpus_allowed
3391 cpumask_copy(new_mask
, cpus_allowed
);
3396 free_cpumask_var(new_mask
);
3397 out_free_cpus_allowed
:
3398 free_cpumask_var(cpus_allowed
);
3404 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3405 struct cpumask
*new_mask
)
3407 if (len
< cpumask_size())
3408 cpumask_clear(new_mask
);
3409 else if (len
> cpumask_size())
3410 len
= cpumask_size();
3412 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3416 * sys_sched_setaffinity - set the cpu affinity of a process
3417 * @pid: pid of the process
3418 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3419 * @user_mask_ptr: user-space pointer to the new cpu mask
3421 * Return: 0 on success. An error code otherwise.
3423 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
3424 unsigned long __user
*, user_mask_ptr
)
3426 cpumask_var_t new_mask
;
3429 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
3432 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
3434 retval
= sched_setaffinity(pid
, new_mask
);
3435 free_cpumask_var(new_mask
);
3439 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
3441 struct task_struct
*p
;
3442 unsigned long flags
;
3448 p
= find_process_by_pid(pid
);
3452 retval
= security_task_getscheduler(p
);
3456 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
3457 cpumask_and(mask
, &p
->cpus_allowed
, cpu_active_mask
);
3458 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
3467 * sys_sched_getaffinity - get the cpu affinity of a process
3468 * @pid: pid of the process
3469 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3470 * @user_mask_ptr: user-space pointer to hold the current cpu mask
3472 * Return: 0 on success. An error code otherwise.
3474 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
3475 unsigned long __user
*, user_mask_ptr
)
3480 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
3482 if (len
& (sizeof(unsigned long)-1))
3485 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
3488 ret
= sched_getaffinity(pid
, mask
);
3490 size_t retlen
= min_t(size_t, len
, cpumask_size());
3492 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
3497 free_cpumask_var(mask
);
3503 * sys_sched_yield - yield the current processor to other threads.
3505 * This function yields the current CPU to other tasks. If there are no
3506 * other threads running on this CPU then this function will return.
3510 SYSCALL_DEFINE0(sched_yield
)
3512 struct rq
*rq
= this_rq_lock();
3514 schedstat_inc(rq
, yld_count
);
3515 current
->sched_class
->yield_task(rq
);
3518 * Since we are going to call schedule() anyway, there's
3519 * no need to preempt or enable interrupts:
3521 __release(rq
->lock
);
3522 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
3523 do_raw_spin_unlock(&rq
->lock
);
3524 sched_preempt_enable_no_resched();
3531 static void __cond_resched(void)
3533 __preempt_count_add(PREEMPT_ACTIVE
);
3535 __preempt_count_sub(PREEMPT_ACTIVE
);
3538 int __sched
_cond_resched(void)
3540 if (should_resched()) {
3546 EXPORT_SYMBOL(_cond_resched
);
3549 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
3550 * call schedule, and on return reacquire the lock.
3552 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
3553 * operations here to prevent schedule() from being called twice (once via
3554 * spin_unlock(), once by hand).
3556 int __cond_resched_lock(spinlock_t
*lock
)
3558 int resched
= should_resched();
3561 lockdep_assert_held(lock
);
3563 if (spin_needbreak(lock
) || resched
) {
3574 EXPORT_SYMBOL(__cond_resched_lock
);
3576 int __sched
__cond_resched_softirq(void)
3578 BUG_ON(!in_softirq());
3580 if (should_resched()) {
3588 EXPORT_SYMBOL(__cond_resched_softirq
);
3591 * yield - yield the current processor to other threads.
3593 * Do not ever use this function, there's a 99% chance you're doing it wrong.
3595 * The scheduler is at all times free to pick the calling task as the most
3596 * eligible task to run, if removing the yield() call from your code breaks
3597 * it, its already broken.
3599 * Typical broken usage is:
3604 * where one assumes that yield() will let 'the other' process run that will
3605 * make event true. If the current task is a SCHED_FIFO task that will never
3606 * happen. Never use yield() as a progress guarantee!!
3608 * If you want to use yield() to wait for something, use wait_event().
3609 * If you want to use yield() to be 'nice' for others, use cond_resched().
3610 * If you still want to use yield(), do not!
3612 void __sched
yield(void)
3614 set_current_state(TASK_RUNNING
);
3617 EXPORT_SYMBOL(yield
);
3620 * yield_to - yield the current processor to another thread in
3621 * your thread group, or accelerate that thread toward the
3622 * processor it's on.
3624 * @preempt: whether task preemption is allowed or not
3626 * It's the caller's job to ensure that the target task struct
3627 * can't go away on us before we can do any checks.
3630 * true (>0) if we indeed boosted the target task.
3631 * false (0) if we failed to boost the target.
3632 * -ESRCH if there's no task to yield to.
3634 bool __sched
yield_to(struct task_struct
*p
, bool preempt
)
3636 struct task_struct
*curr
= current
;
3637 struct rq
*rq
, *p_rq
;
3638 unsigned long flags
;
3641 local_irq_save(flags
);
3647 * If we're the only runnable task on the rq and target rq also
3648 * has only one task, there's absolutely no point in yielding.
3650 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
3655 double_rq_lock(rq
, p_rq
);
3656 while (task_rq(p
) != p_rq
) {
3657 double_rq_unlock(rq
, p_rq
);
3661 if (!curr
->sched_class
->yield_to_task
)
3664 if (curr
->sched_class
!= p
->sched_class
)
3667 if (task_running(p_rq
, p
) || p
->state
)
3670 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
3672 schedstat_inc(rq
, yld_count
);
3674 * Make p's CPU reschedule; pick_next_entity takes care of
3677 if (preempt
&& rq
!= p_rq
)
3678 resched_task(p_rq
->curr
);
3682 double_rq_unlock(rq
, p_rq
);
3684 local_irq_restore(flags
);
3691 EXPORT_SYMBOL_GPL(yield_to
);
3694 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3695 * that process accounting knows that this is a task in IO wait state.
3697 void __sched
io_schedule(void)
3699 struct rq
*rq
= raw_rq();
3701 delayacct_blkio_start();
3702 atomic_inc(&rq
->nr_iowait
);
3703 blk_flush_plug(current
);
3704 current
->in_iowait
= 1;
3706 current
->in_iowait
= 0;
3707 atomic_dec(&rq
->nr_iowait
);
3708 delayacct_blkio_end();
3710 EXPORT_SYMBOL(io_schedule
);
3712 long __sched
io_schedule_timeout(long timeout
)
3714 struct rq
*rq
= raw_rq();
3717 delayacct_blkio_start();
3718 atomic_inc(&rq
->nr_iowait
);
3719 blk_flush_plug(current
);
3720 current
->in_iowait
= 1;
3721 ret
= schedule_timeout(timeout
);
3722 current
->in_iowait
= 0;
3723 atomic_dec(&rq
->nr_iowait
);
3724 delayacct_blkio_end();
3729 * sys_sched_get_priority_max - return maximum RT priority.
3730 * @policy: scheduling class.
3732 * Return: On success, this syscall returns the maximum
3733 * rt_priority that can be used by a given scheduling class.
3734 * On failure, a negative error code is returned.
3736 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
3743 ret
= MAX_USER_RT_PRIO
-1;
3755 * sys_sched_get_priority_min - return minimum RT priority.
3756 * @policy: scheduling class.
3758 * Return: On success, this syscall returns the minimum
3759 * rt_priority that can be used by a given scheduling class.
3760 * On failure, a negative error code is returned.
3762 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
3780 * sys_sched_rr_get_interval - return the default timeslice of a process.
3781 * @pid: pid of the process.
3782 * @interval: userspace pointer to the timeslice value.
3784 * this syscall writes the default timeslice value of a given process
3785 * into the user-space timespec buffer. A value of '0' means infinity.
3787 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
3790 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
3791 struct timespec __user
*, interval
)
3793 struct task_struct
*p
;
3794 unsigned int time_slice
;
3795 unsigned long flags
;
3805 p
= find_process_by_pid(pid
);
3809 retval
= security_task_getscheduler(p
);
3813 rq
= task_rq_lock(p
, &flags
);
3814 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
3815 task_rq_unlock(rq
, p
, &flags
);
3818 jiffies_to_timespec(time_slice
, &t
);
3819 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
3827 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
3829 void sched_show_task(struct task_struct
*p
)
3831 unsigned long free
= 0;
3835 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
3836 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
3837 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
3838 #if BITS_PER_LONG == 32
3839 if (state
== TASK_RUNNING
)
3840 printk(KERN_CONT
" running ");
3842 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
3844 if (state
== TASK_RUNNING
)
3845 printk(KERN_CONT
" running task ");
3847 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
3849 #ifdef CONFIG_DEBUG_STACK_USAGE
3850 free
= stack_not_used(p
);
3853 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
3855 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
3856 task_pid_nr(p
), ppid
,
3857 (unsigned long)task_thread_info(p
)->flags
);
3859 print_worker_info(KERN_INFO
, p
);
3860 show_stack(p
, NULL
);
3863 void show_state_filter(unsigned long state_filter
)
3865 struct task_struct
*g
, *p
;
3867 #if BITS_PER_LONG == 32
3869 " task PC stack pid father\n");
3872 " task PC stack pid father\n");
3875 do_each_thread(g
, p
) {
3877 * reset the NMI-timeout, listing all files on a slow
3878 * console might take a lot of time:
3880 touch_nmi_watchdog();
3881 if (!state_filter
|| (p
->state
& state_filter
))
3883 } while_each_thread(g
, p
);
3885 touch_all_softlockup_watchdogs();
3887 #ifdef CONFIG_SCHED_DEBUG
3888 sysrq_sched_debug_show();
3892 * Only show locks if all tasks are dumped:
3895 debug_show_all_locks();
3898 void init_idle_bootup_task(struct task_struct
*idle
)
3900 idle
->sched_class
= &idle_sched_class
;
3904 * init_idle - set up an idle thread for a given CPU
3905 * @idle: task in question
3906 * @cpu: cpu the idle task belongs to
3908 * NOTE: this function does not set the idle thread's NEED_RESCHED
3909 * flag, to make booting more robust.
3911 void init_idle(struct task_struct
*idle
, int cpu
)
3913 struct rq
*rq
= cpu_rq(cpu
);
3914 unsigned long flags
;
3916 raw_spin_lock_irqsave(&rq
->lock
, flags
);
3918 __sched_fork(0, idle
);
3919 idle
->state
= TASK_RUNNING
;
3920 idle
->se
.exec_start
= sched_clock();
3922 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
3924 * We're having a chicken and egg problem, even though we are
3925 * holding rq->lock, the cpu isn't yet set to this cpu so the
3926 * lockdep check in task_group() will fail.
3928 * Similar case to sched_fork(). / Alternatively we could
3929 * use task_rq_lock() here and obtain the other rq->lock.
3934 __set_task_cpu(idle
, cpu
);
3937 rq
->curr
= rq
->idle
= idle
;
3938 #if defined(CONFIG_SMP)
3941 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
3943 /* Set the preempt count _outside_ the spinlocks! */
3944 init_idle_preempt_count(idle
, cpu
);
3947 * The idle tasks have their own, simple scheduling class:
3949 idle
->sched_class
= &idle_sched_class
;
3950 ftrace_graph_init_idle_task(idle
, cpu
);
3951 vtime_init_idle(idle
, cpu
);
3952 #if defined(CONFIG_SMP)
3953 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
3958 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
3960 if (p
->sched_class
&& p
->sched_class
->set_cpus_allowed
)
3961 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
3963 cpumask_copy(&p
->cpus_allowed
, new_mask
);
3964 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
3968 * This is how migration works:
3970 * 1) we invoke migration_cpu_stop() on the target CPU using
3972 * 2) stopper starts to run (implicitly forcing the migrated thread
3974 * 3) it checks whether the migrated task is still in the wrong runqueue.
3975 * 4) if it's in the wrong runqueue then the migration thread removes
3976 * it and puts it into the right queue.
3977 * 5) stopper completes and stop_one_cpu() returns and the migration
3982 * Change a given task's CPU affinity. Migrate the thread to a
3983 * proper CPU and schedule it away if the CPU it's executing on
3984 * is removed from the allowed bitmask.
3986 * NOTE: the caller must have a valid reference to the task, the
3987 * task must not exit() & deallocate itself prematurely. The
3988 * call is not atomic; no spinlocks may be held.
3990 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
3992 unsigned long flags
;
3994 unsigned int dest_cpu
;
3997 rq
= task_rq_lock(p
, &flags
);
3999 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
4002 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
4007 do_set_cpus_allowed(p
, new_mask
);
4009 /* Can the task run on the task's current CPU? If so, we're done */
4010 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
4013 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
4015 struct migration_arg arg
= { p
, dest_cpu
};
4016 /* Need help from migration thread: drop lock and wait. */
4017 task_rq_unlock(rq
, p
, &flags
);
4018 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
4019 tlb_migrate_finish(p
->mm
);
4023 task_rq_unlock(rq
, p
, &flags
);
4027 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
4030 * Move (not current) task off this cpu, onto dest cpu. We're doing
4031 * this because either it can't run here any more (set_cpus_allowed()
4032 * away from this CPU, or CPU going down), or because we're
4033 * attempting to rebalance this task on exec (sched_exec).
4035 * So we race with normal scheduler movements, but that's OK, as long
4036 * as the task is no longer on this CPU.
4038 * Returns non-zero if task was successfully migrated.
4040 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4042 struct rq
*rq_dest
, *rq_src
;
4045 if (unlikely(!cpu_active(dest_cpu
)))
4048 rq_src
= cpu_rq(src_cpu
);
4049 rq_dest
= cpu_rq(dest_cpu
);
4051 raw_spin_lock(&p
->pi_lock
);
4052 double_rq_lock(rq_src
, rq_dest
);
4053 /* Already moved. */
4054 if (task_cpu(p
) != src_cpu
)
4056 /* Affinity changed (again). */
4057 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
4061 * If we're not on a rq, the next wake-up will ensure we're
4065 dequeue_task(rq_src
, p
, 0);
4066 set_task_cpu(p
, dest_cpu
);
4067 enqueue_task(rq_dest
, p
, 0);
4068 check_preempt_curr(rq_dest
, p
, 0);
4073 double_rq_unlock(rq_src
, rq_dest
);
4074 raw_spin_unlock(&p
->pi_lock
);
4078 #ifdef CONFIG_NUMA_BALANCING
4079 /* Migrate current task p to target_cpu */
4080 int migrate_task_to(struct task_struct
*p
, int target_cpu
)
4082 struct migration_arg arg
= { p
, target_cpu
};
4083 int curr_cpu
= task_cpu(p
);
4085 if (curr_cpu
== target_cpu
)
4088 if (!cpumask_test_cpu(target_cpu
, tsk_cpus_allowed(p
)))
4091 /* TODO: This is not properly updating schedstats */
4093 return stop_one_cpu(curr_cpu
, migration_cpu_stop
, &arg
);
4097 * Requeue a task on a given node and accurately track the number of NUMA
4098 * tasks on the runqueues
4100 void sched_setnuma(struct task_struct
*p
, int nid
)
4103 unsigned long flags
;
4104 bool on_rq
, running
;
4106 rq
= task_rq_lock(p
, &flags
);
4108 running
= task_current(rq
, p
);
4111 dequeue_task(rq
, p
, 0);
4113 p
->sched_class
->put_prev_task(rq
, p
);
4115 p
->numa_preferred_nid
= nid
;
4118 p
->sched_class
->set_curr_task(rq
);
4120 enqueue_task(rq
, p
, 0);
4121 task_rq_unlock(rq
, p
, &flags
);
4126 * migration_cpu_stop - this will be executed by a highprio stopper thread
4127 * and performs thread migration by bumping thread off CPU then
4128 * 'pushing' onto another runqueue.
4130 static int migration_cpu_stop(void *data
)
4132 struct migration_arg
*arg
= data
;
4135 * The original target cpu might have gone down and we might
4136 * be on another cpu but it doesn't matter.
4138 local_irq_disable();
4139 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
4144 #ifdef CONFIG_HOTPLUG_CPU
4147 * Ensures that the idle task is using init_mm right before its cpu goes
4150 void idle_task_exit(void)
4152 struct mm_struct
*mm
= current
->active_mm
;
4154 BUG_ON(cpu_online(smp_processor_id()));
4157 switch_mm(mm
, &init_mm
, current
);
4162 * Since this CPU is going 'away' for a while, fold any nr_active delta
4163 * we might have. Assumes we're called after migrate_tasks() so that the
4164 * nr_active count is stable.
4166 * Also see the comment "Global load-average calculations".
4168 static void calc_load_migrate(struct rq
*rq
)
4170 long delta
= calc_load_fold_active(rq
);
4172 atomic_long_add(delta
, &calc_load_tasks
);
4176 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4177 * try_to_wake_up()->select_task_rq().
4179 * Called with rq->lock held even though we'er in stop_machine() and
4180 * there's no concurrency possible, we hold the required locks anyway
4181 * because of lock validation efforts.
4183 static void migrate_tasks(unsigned int dead_cpu
)
4185 struct rq
*rq
= cpu_rq(dead_cpu
);
4186 struct task_struct
*next
, *stop
= rq
->stop
;
4190 * Fudge the rq selection such that the below task selection loop
4191 * doesn't get stuck on the currently eligible stop task.
4193 * We're currently inside stop_machine() and the rq is either stuck
4194 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4195 * either way we should never end up calling schedule() until we're
4201 * put_prev_task() and pick_next_task() sched
4202 * class method both need to have an up-to-date
4203 * value of rq->clock[_task]
4205 update_rq_clock(rq
);
4209 * There's this thread running, bail when that's the only
4212 if (rq
->nr_running
== 1)
4215 next
= pick_next_task(rq
);
4217 next
->sched_class
->put_prev_task(rq
, next
);
4219 /* Find suitable destination for @next, with force if needed. */
4220 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
4221 raw_spin_unlock(&rq
->lock
);
4223 __migrate_task(next
, dead_cpu
, dest_cpu
);
4225 raw_spin_lock(&rq
->lock
);
4231 #endif /* CONFIG_HOTPLUG_CPU */
4233 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4235 static struct ctl_table sd_ctl_dir
[] = {
4237 .procname
= "sched_domain",
4243 static struct ctl_table sd_ctl_root
[] = {
4245 .procname
= "kernel",
4247 .child
= sd_ctl_dir
,
4252 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
4254 struct ctl_table
*entry
=
4255 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
4260 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
4262 struct ctl_table
*entry
;
4265 * In the intermediate directories, both the child directory and
4266 * procname are dynamically allocated and could fail but the mode
4267 * will always be set. In the lowest directory the names are
4268 * static strings and all have proc handlers.
4270 for (entry
= *tablep
; entry
->mode
; entry
++) {
4272 sd_free_ctl_entry(&entry
->child
);
4273 if (entry
->proc_handler
== NULL
)
4274 kfree(entry
->procname
);
4281 static int min_load_idx
= 0;
4282 static int max_load_idx
= CPU_LOAD_IDX_MAX
-1;
4285 set_table_entry(struct ctl_table
*entry
,
4286 const char *procname
, void *data
, int maxlen
,
4287 umode_t mode
, proc_handler
*proc_handler
,
4290 entry
->procname
= procname
;
4292 entry
->maxlen
= maxlen
;
4294 entry
->proc_handler
= proc_handler
;
4297 entry
->extra1
= &min_load_idx
;
4298 entry
->extra2
= &max_load_idx
;
4302 static struct ctl_table
*
4303 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
4305 struct ctl_table
*table
= sd_alloc_ctl_entry(13);
4310 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
4311 sizeof(long), 0644, proc_doulongvec_minmax
, false);
4312 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
4313 sizeof(long), 0644, proc_doulongvec_minmax
, false);
4314 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
4315 sizeof(int), 0644, proc_dointvec_minmax
, true);
4316 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
4317 sizeof(int), 0644, proc_dointvec_minmax
, true);
4318 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
4319 sizeof(int), 0644, proc_dointvec_minmax
, true);
4320 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
4321 sizeof(int), 0644, proc_dointvec_minmax
, true);
4322 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
4323 sizeof(int), 0644, proc_dointvec_minmax
, true);
4324 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
4325 sizeof(int), 0644, proc_dointvec_minmax
, false);
4326 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
4327 sizeof(int), 0644, proc_dointvec_minmax
, false);
4328 set_table_entry(&table
[9], "cache_nice_tries",
4329 &sd
->cache_nice_tries
,
4330 sizeof(int), 0644, proc_dointvec_minmax
, false);
4331 set_table_entry(&table
[10], "flags", &sd
->flags
,
4332 sizeof(int), 0644, proc_dointvec_minmax
, false);
4333 set_table_entry(&table
[11], "name", sd
->name
,
4334 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
4335 /* &table[12] is terminator */
4340 static struct ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
4342 struct ctl_table
*entry
, *table
;
4343 struct sched_domain
*sd
;
4344 int domain_num
= 0, i
;
4347 for_each_domain(cpu
, sd
)
4349 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
4354 for_each_domain(cpu
, sd
) {
4355 snprintf(buf
, 32, "domain%d", i
);
4356 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
4358 entry
->child
= sd_alloc_ctl_domain_table(sd
);
4365 static struct ctl_table_header
*sd_sysctl_header
;
4366 static void register_sched_domain_sysctl(void)
4368 int i
, cpu_num
= num_possible_cpus();
4369 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
4372 WARN_ON(sd_ctl_dir
[0].child
);
4373 sd_ctl_dir
[0].child
= entry
;
4378 for_each_possible_cpu(i
) {
4379 snprintf(buf
, 32, "cpu%d", i
);
4380 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
4382 entry
->child
= sd_alloc_ctl_cpu_table(i
);
4386 WARN_ON(sd_sysctl_header
);
4387 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
4390 /* may be called multiple times per register */
4391 static void unregister_sched_domain_sysctl(void)
4393 if (sd_sysctl_header
)
4394 unregister_sysctl_table(sd_sysctl_header
);
4395 sd_sysctl_header
= NULL
;
4396 if (sd_ctl_dir
[0].child
)
4397 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
4400 static void register_sched_domain_sysctl(void)
4403 static void unregister_sched_domain_sysctl(void)
4408 static void set_rq_online(struct rq
*rq
)
4411 const struct sched_class
*class;
4413 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
4416 for_each_class(class) {
4417 if (class->rq_online
)
4418 class->rq_online(rq
);
4423 static void set_rq_offline(struct rq
*rq
)
4426 const struct sched_class
*class;
4428 for_each_class(class) {
4429 if (class->rq_offline
)
4430 class->rq_offline(rq
);
4433 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
4439 * migration_call - callback that gets triggered when a CPU is added.
4440 * Here we can start up the necessary migration thread for the new CPU.
4443 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
4445 int cpu
= (long)hcpu
;
4446 unsigned long flags
;
4447 struct rq
*rq
= cpu_rq(cpu
);
4449 switch (action
& ~CPU_TASKS_FROZEN
) {
4451 case CPU_UP_PREPARE
:
4452 rq
->calc_load_update
= calc_load_update
;
4456 /* Update our root-domain */
4457 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4459 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
4463 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4466 #ifdef CONFIG_HOTPLUG_CPU
4468 sched_ttwu_pending();
4469 /* Update our root-domain */
4470 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4472 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
4476 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
4477 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4481 calc_load_migrate(rq
);
4486 update_max_interval();
4492 * Register at high priority so that task migration (migrate_all_tasks)
4493 * happens before everything else. This has to be lower priority than
4494 * the notifier in the perf_event subsystem, though.
4496 static struct notifier_block migration_notifier
= {
4497 .notifier_call
= migration_call
,
4498 .priority
= CPU_PRI_MIGRATION
,
4501 static int sched_cpu_active(struct notifier_block
*nfb
,
4502 unsigned long action
, void *hcpu
)
4504 switch (action
& ~CPU_TASKS_FROZEN
) {
4506 case CPU_DOWN_FAILED
:
4507 set_cpu_active((long)hcpu
, true);
4514 static int sched_cpu_inactive(struct notifier_block
*nfb
,
4515 unsigned long action
, void *hcpu
)
4517 switch (action
& ~CPU_TASKS_FROZEN
) {
4518 case CPU_DOWN_PREPARE
:
4519 set_cpu_active((long)hcpu
, false);
4526 static int __init
migration_init(void)
4528 void *cpu
= (void *)(long)smp_processor_id();
4531 /* Initialize migration for the boot CPU */
4532 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4533 BUG_ON(err
== NOTIFY_BAD
);
4534 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4535 register_cpu_notifier(&migration_notifier
);
4537 /* Register cpu active notifiers */
4538 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
4539 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
4543 early_initcall(migration_init
);
4548 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
4550 #ifdef CONFIG_SCHED_DEBUG
4552 static __read_mostly
int sched_debug_enabled
;
4554 static int __init
sched_debug_setup(char *str
)
4556 sched_debug_enabled
= 1;
4560 early_param("sched_debug", sched_debug_setup
);
4562 static inline bool sched_debug(void)
4564 return sched_debug_enabled
;
4567 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
4568 struct cpumask
*groupmask
)
4570 struct sched_group
*group
= sd
->groups
;
4573 cpulist_scnprintf(str
, sizeof(str
), sched_domain_span(sd
));
4574 cpumask_clear(groupmask
);
4576 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
4578 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4579 printk("does not load-balance\n");
4581 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
4586 printk(KERN_CONT
"span %s level %s\n", str
, sd
->name
);
4588 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
4589 printk(KERN_ERR
"ERROR: domain->span does not contain "
4592 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
4593 printk(KERN_ERR
"ERROR: domain->groups does not contain"
4597 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
4601 printk(KERN_ERR
"ERROR: group is NULL\n");
4606 * Even though we initialize ->power to something semi-sane,
4607 * we leave power_orig unset. This allows us to detect if
4608 * domain iteration is still funny without causing /0 traps.
4610 if (!group
->sgp
->power_orig
) {
4611 printk(KERN_CONT
"\n");
4612 printk(KERN_ERR
"ERROR: domain->cpu_power not "
4617 if (!cpumask_weight(sched_group_cpus(group
))) {
4618 printk(KERN_CONT
"\n");
4619 printk(KERN_ERR
"ERROR: empty group\n");
4623 if (!(sd
->flags
& SD_OVERLAP
) &&
4624 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
4625 printk(KERN_CONT
"\n");
4626 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4630 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
4632 cpulist_scnprintf(str
, sizeof(str
), sched_group_cpus(group
));
4634 printk(KERN_CONT
" %s", str
);
4635 if (group
->sgp
->power
!= SCHED_POWER_SCALE
) {
4636 printk(KERN_CONT
" (cpu_power = %d)",
4640 group
= group
->next
;
4641 } while (group
!= sd
->groups
);
4642 printk(KERN_CONT
"\n");
4644 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
4645 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4648 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
4649 printk(KERN_ERR
"ERROR: parent span is not a superset "
4650 "of domain->span\n");
4654 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4658 if (!sched_debug_enabled
)
4662 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4666 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4669 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
4677 #else /* !CONFIG_SCHED_DEBUG */
4678 # define sched_domain_debug(sd, cpu) do { } while (0)
4679 static inline bool sched_debug(void)
4683 #endif /* CONFIG_SCHED_DEBUG */
4685 static int sd_degenerate(struct sched_domain
*sd
)
4687 if (cpumask_weight(sched_domain_span(sd
)) == 1)
4690 /* Following flags need at least 2 groups */
4691 if (sd
->flags
& (SD_LOAD_BALANCE
|
4692 SD_BALANCE_NEWIDLE
|
4696 SD_SHARE_PKG_RESOURCES
)) {
4697 if (sd
->groups
!= sd
->groups
->next
)
4701 /* Following flags don't use groups */
4702 if (sd
->flags
& (SD_WAKE_AFFINE
))
4709 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
4711 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
4713 if (sd_degenerate(parent
))
4716 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
4719 /* Flags needing groups don't count if only 1 group in parent */
4720 if (parent
->groups
== parent
->groups
->next
) {
4721 pflags
&= ~(SD_LOAD_BALANCE
|
4722 SD_BALANCE_NEWIDLE
|
4726 SD_SHARE_PKG_RESOURCES
|
4728 if (nr_node_ids
== 1)
4729 pflags
&= ~SD_SERIALIZE
;
4731 if (~cflags
& pflags
)
4737 static void free_rootdomain(struct rcu_head
*rcu
)
4739 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
4741 cpupri_cleanup(&rd
->cpupri
);
4742 free_cpumask_var(rd
->rto_mask
);
4743 free_cpumask_var(rd
->online
);
4744 free_cpumask_var(rd
->span
);
4748 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
4750 struct root_domain
*old_rd
= NULL
;
4751 unsigned long flags
;
4753 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4758 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
4761 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
4764 * If we dont want to free the old_rd yet then
4765 * set old_rd to NULL to skip the freeing later
4768 if (!atomic_dec_and_test(&old_rd
->refcount
))
4772 atomic_inc(&rd
->refcount
);
4775 cpumask_set_cpu(rq
->cpu
, rd
->span
);
4776 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
4779 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4782 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
4785 static int init_rootdomain(struct root_domain
*rd
)
4787 memset(rd
, 0, sizeof(*rd
));
4789 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
4791 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
4793 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
4796 if (cpupri_init(&rd
->cpupri
) != 0)
4801 free_cpumask_var(rd
->rto_mask
);
4803 free_cpumask_var(rd
->online
);
4805 free_cpumask_var(rd
->span
);
4811 * By default the system creates a single root-domain with all cpus as
4812 * members (mimicking the global state we have today).
4814 struct root_domain def_root_domain
;
4816 static void init_defrootdomain(void)
4818 init_rootdomain(&def_root_domain
);
4820 atomic_set(&def_root_domain
.refcount
, 1);
4823 static struct root_domain
*alloc_rootdomain(void)
4825 struct root_domain
*rd
;
4827 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
4831 if (init_rootdomain(rd
) != 0) {
4839 static void free_sched_groups(struct sched_group
*sg
, int free_sgp
)
4841 struct sched_group
*tmp
, *first
;
4850 if (free_sgp
&& atomic_dec_and_test(&sg
->sgp
->ref
))
4855 } while (sg
!= first
);
4858 static void free_sched_domain(struct rcu_head
*rcu
)
4860 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
4863 * If its an overlapping domain it has private groups, iterate and
4866 if (sd
->flags
& SD_OVERLAP
) {
4867 free_sched_groups(sd
->groups
, 1);
4868 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
4869 kfree(sd
->groups
->sgp
);
4875 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
4877 call_rcu(&sd
->rcu
, free_sched_domain
);
4880 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
4882 for (; sd
; sd
= sd
->parent
)
4883 destroy_sched_domain(sd
, cpu
);
4887 * Keep a special pointer to the highest sched_domain that has
4888 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
4889 * allows us to avoid some pointer chasing select_idle_sibling().
4891 * Also keep a unique ID per domain (we use the first cpu number in
4892 * the cpumask of the domain), this allows us to quickly tell if
4893 * two cpus are in the same cache domain, see cpus_share_cache().
4895 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
4896 DEFINE_PER_CPU(int, sd_llc_size
);
4897 DEFINE_PER_CPU(int, sd_llc_id
);
4898 DEFINE_PER_CPU(struct sched_domain
*, sd_numa
);
4899 DEFINE_PER_CPU(struct sched_domain
*, sd_busy
);
4900 DEFINE_PER_CPU(struct sched_domain
*, sd_asym
);
4902 static void update_top_cache_domain(int cpu
)
4904 struct sched_domain
*sd
;
4908 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
4910 id
= cpumask_first(sched_domain_span(sd
));
4911 size
= cpumask_weight(sched_domain_span(sd
));
4912 sd
= sd
->parent
; /* sd_busy */
4914 rcu_assign_pointer(per_cpu(sd_busy
, cpu
), sd
);
4916 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
4917 per_cpu(sd_llc_size
, cpu
) = size
;
4918 per_cpu(sd_llc_id
, cpu
) = id
;
4920 sd
= lowest_flag_domain(cpu
, SD_NUMA
);
4921 rcu_assign_pointer(per_cpu(sd_numa
, cpu
), sd
);
4923 sd
= highest_flag_domain(cpu
, SD_ASYM_PACKING
);
4924 rcu_assign_pointer(per_cpu(sd_asym
, cpu
), sd
);
4928 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4929 * hold the hotplug lock.
4932 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
4934 struct rq
*rq
= cpu_rq(cpu
);
4935 struct sched_domain
*tmp
;
4937 /* Remove the sched domains which do not contribute to scheduling. */
4938 for (tmp
= sd
; tmp
; ) {
4939 struct sched_domain
*parent
= tmp
->parent
;
4943 if (sd_parent_degenerate(tmp
, parent
)) {
4944 tmp
->parent
= parent
->parent
;
4946 parent
->parent
->child
= tmp
;
4948 * Transfer SD_PREFER_SIBLING down in case of a
4949 * degenerate parent; the spans match for this
4950 * so the property transfers.
4952 if (parent
->flags
& SD_PREFER_SIBLING
)
4953 tmp
->flags
|= SD_PREFER_SIBLING
;
4954 destroy_sched_domain(parent
, cpu
);
4959 if (sd
&& sd_degenerate(sd
)) {
4962 destroy_sched_domain(tmp
, cpu
);
4967 sched_domain_debug(sd
, cpu
);
4969 rq_attach_root(rq
, rd
);
4971 rcu_assign_pointer(rq
->sd
, sd
);
4972 destroy_sched_domains(tmp
, cpu
);
4974 update_top_cache_domain(cpu
);
4977 /* cpus with isolated domains */
4978 static cpumask_var_t cpu_isolated_map
;
4980 /* Setup the mask of cpus configured for isolated domains */
4981 static int __init
isolated_cpu_setup(char *str
)
4983 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
4984 cpulist_parse(str
, cpu_isolated_map
);
4988 __setup("isolcpus=", isolated_cpu_setup
);
4990 static const struct cpumask
*cpu_cpu_mask(int cpu
)
4992 return cpumask_of_node(cpu_to_node(cpu
));
4996 struct sched_domain
**__percpu sd
;
4997 struct sched_group
**__percpu sg
;
4998 struct sched_group_power
**__percpu sgp
;
5002 struct sched_domain
** __percpu sd
;
5003 struct root_domain
*rd
;
5013 struct sched_domain_topology_level
;
5015 typedef struct sched_domain
*(*sched_domain_init_f
)(struct sched_domain_topology_level
*tl
, int cpu
);
5016 typedef const struct cpumask
*(*sched_domain_mask_f
)(int cpu
);
5018 #define SDTL_OVERLAP 0x01
5020 struct sched_domain_topology_level
{
5021 sched_domain_init_f init
;
5022 sched_domain_mask_f mask
;
5025 struct sd_data data
;
5029 * Build an iteration mask that can exclude certain CPUs from the upwards
5032 * Asymmetric node setups can result in situations where the domain tree is of
5033 * unequal depth, make sure to skip domains that already cover the entire
5036 * In that case build_sched_domains() will have terminated the iteration early
5037 * and our sibling sd spans will be empty. Domains should always include the
5038 * cpu they're built on, so check that.
5041 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
5043 const struct cpumask
*span
= sched_domain_span(sd
);
5044 struct sd_data
*sdd
= sd
->private;
5045 struct sched_domain
*sibling
;
5048 for_each_cpu(i
, span
) {
5049 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5050 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5053 cpumask_set_cpu(i
, sched_group_mask(sg
));
5058 * Return the canonical balance cpu for this group, this is the first cpu
5059 * of this group that's also in the iteration mask.
5061 int group_balance_cpu(struct sched_group
*sg
)
5063 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
5067 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
5069 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
5070 const struct cpumask
*span
= sched_domain_span(sd
);
5071 struct cpumask
*covered
= sched_domains_tmpmask
;
5072 struct sd_data
*sdd
= sd
->private;
5073 struct sched_domain
*child
;
5076 cpumask_clear(covered
);
5078 for_each_cpu(i
, span
) {
5079 struct cpumask
*sg_span
;
5081 if (cpumask_test_cpu(i
, covered
))
5084 child
= *per_cpu_ptr(sdd
->sd
, i
);
5086 /* See the comment near build_group_mask(). */
5087 if (!cpumask_test_cpu(i
, sched_domain_span(child
)))
5090 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5091 GFP_KERNEL
, cpu_to_node(cpu
));
5096 sg_span
= sched_group_cpus(sg
);
5098 child
= child
->child
;
5099 cpumask_copy(sg_span
, sched_domain_span(child
));
5101 cpumask_set_cpu(i
, sg_span
);
5103 cpumask_or(covered
, covered
, sg_span
);
5105 sg
->sgp
= *per_cpu_ptr(sdd
->sgp
, i
);
5106 if (atomic_inc_return(&sg
->sgp
->ref
) == 1)
5107 build_group_mask(sd
, sg
);
5110 * Initialize sgp->power such that even if we mess up the
5111 * domains and no possible iteration will get us here, we won't
5114 sg
->sgp
->power
= SCHED_POWER_SCALE
* cpumask_weight(sg_span
);
5117 * Make sure the first group of this domain contains the
5118 * canonical balance cpu. Otherwise the sched_domain iteration
5119 * breaks. See update_sg_lb_stats().
5121 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
5122 group_balance_cpu(sg
) == cpu
)
5132 sd
->groups
= groups
;
5137 free_sched_groups(first
, 0);
5142 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
5144 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
5145 struct sched_domain
*child
= sd
->child
;
5148 cpu
= cpumask_first(sched_domain_span(child
));
5151 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
5152 (*sg
)->sgp
= *per_cpu_ptr(sdd
->sgp
, cpu
);
5153 atomic_set(&(*sg
)->sgp
->ref
, 1); /* for claim_allocations */
5160 * build_sched_groups will build a circular linked list of the groups
5161 * covered by the given span, and will set each group's ->cpumask correctly,
5162 * and ->cpu_power to 0.
5164 * Assumes the sched_domain tree is fully constructed
5167 build_sched_groups(struct sched_domain
*sd
, int cpu
)
5169 struct sched_group
*first
= NULL
, *last
= NULL
;
5170 struct sd_data
*sdd
= sd
->private;
5171 const struct cpumask
*span
= sched_domain_span(sd
);
5172 struct cpumask
*covered
;
5175 get_group(cpu
, sdd
, &sd
->groups
);
5176 atomic_inc(&sd
->groups
->ref
);
5178 if (cpu
!= cpumask_first(span
))
5181 lockdep_assert_held(&sched_domains_mutex
);
5182 covered
= sched_domains_tmpmask
;
5184 cpumask_clear(covered
);
5186 for_each_cpu(i
, span
) {
5187 struct sched_group
*sg
;
5190 if (cpumask_test_cpu(i
, covered
))
5193 group
= get_group(i
, sdd
, &sg
);
5194 cpumask_clear(sched_group_cpus(sg
));
5196 cpumask_setall(sched_group_mask(sg
));
5198 for_each_cpu(j
, span
) {
5199 if (get_group(j
, sdd
, NULL
) != group
)
5202 cpumask_set_cpu(j
, covered
);
5203 cpumask_set_cpu(j
, sched_group_cpus(sg
));
5218 * Initialize sched groups cpu_power.
5220 * cpu_power indicates the capacity of sched group, which is used while
5221 * distributing the load between different sched groups in a sched domain.
5222 * Typically cpu_power for all the groups in a sched domain will be same unless
5223 * there are asymmetries in the topology. If there are asymmetries, group
5224 * having more cpu_power will pickup more load compared to the group having
5227 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5229 struct sched_group
*sg
= sd
->groups
;
5234 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
5236 } while (sg
!= sd
->groups
);
5238 if (cpu
!= group_balance_cpu(sg
))
5241 update_group_power(sd
, cpu
);
5242 atomic_set(&sg
->sgp
->nr_busy_cpus
, sg
->group_weight
);
5245 int __weak
arch_sd_sibling_asym_packing(void)
5247 return 0*SD_ASYM_PACKING
;
5251 * Initializers for schedule domains
5252 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5255 #ifdef CONFIG_SCHED_DEBUG
5256 # define SD_INIT_NAME(sd, type) sd->name = #type
5258 # define SD_INIT_NAME(sd, type) do { } while (0)
5261 #define SD_INIT_FUNC(type) \
5262 static noinline struct sched_domain * \
5263 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5265 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5266 *sd = SD_##type##_INIT; \
5267 SD_INIT_NAME(sd, type); \
5268 sd->private = &tl->data; \
5273 #ifdef CONFIG_SCHED_SMT
5274 SD_INIT_FUNC(SIBLING
)
5276 #ifdef CONFIG_SCHED_MC
5279 #ifdef CONFIG_SCHED_BOOK
5283 static int default_relax_domain_level
= -1;
5284 int sched_domain_level_max
;
5286 static int __init
setup_relax_domain_level(char *str
)
5288 if (kstrtoint(str
, 0, &default_relax_domain_level
))
5289 pr_warn("Unable to set relax_domain_level\n");
5293 __setup("relax_domain_level=", setup_relax_domain_level
);
5295 static void set_domain_attribute(struct sched_domain
*sd
,
5296 struct sched_domain_attr
*attr
)
5300 if (!attr
|| attr
->relax_domain_level
< 0) {
5301 if (default_relax_domain_level
< 0)
5304 request
= default_relax_domain_level
;
5306 request
= attr
->relax_domain_level
;
5307 if (request
< sd
->level
) {
5308 /* turn off idle balance on this domain */
5309 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5311 /* turn on idle balance on this domain */
5312 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
5316 static void __sdt_free(const struct cpumask
*cpu_map
);
5317 static int __sdt_alloc(const struct cpumask
*cpu_map
);
5319 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
5320 const struct cpumask
*cpu_map
)
5324 if (!atomic_read(&d
->rd
->refcount
))
5325 free_rootdomain(&d
->rd
->rcu
); /* fall through */
5327 free_percpu(d
->sd
); /* fall through */
5329 __sdt_free(cpu_map
); /* fall through */
5335 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
5336 const struct cpumask
*cpu_map
)
5338 memset(d
, 0, sizeof(*d
));
5340 if (__sdt_alloc(cpu_map
))
5341 return sa_sd_storage
;
5342 d
->sd
= alloc_percpu(struct sched_domain
*);
5344 return sa_sd_storage
;
5345 d
->rd
= alloc_rootdomain();
5348 return sa_rootdomain
;
5352 * NULL the sd_data elements we've used to build the sched_domain and
5353 * sched_group structure so that the subsequent __free_domain_allocs()
5354 * will not free the data we're using.
5356 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
5358 struct sd_data
*sdd
= sd
->private;
5360 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
5361 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
5363 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
5364 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
5366 if (atomic_read(&(*per_cpu_ptr(sdd
->sgp
, cpu
))->ref
))
5367 *per_cpu_ptr(sdd
->sgp
, cpu
) = NULL
;
5370 #ifdef CONFIG_SCHED_SMT
5371 static const struct cpumask
*cpu_smt_mask(int cpu
)
5373 return topology_thread_cpumask(cpu
);
5378 * Topology list, bottom-up.
5380 static struct sched_domain_topology_level default_topology
[] = {
5381 #ifdef CONFIG_SCHED_SMT
5382 { sd_init_SIBLING
, cpu_smt_mask
, },
5384 #ifdef CONFIG_SCHED_MC
5385 { sd_init_MC
, cpu_coregroup_mask
, },
5387 #ifdef CONFIG_SCHED_BOOK
5388 { sd_init_BOOK
, cpu_book_mask
, },
5390 { sd_init_CPU
, cpu_cpu_mask
, },
5394 static struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
5396 #define for_each_sd_topology(tl) \
5397 for (tl = sched_domain_topology; tl->init; tl++)
5401 static int sched_domains_numa_levels
;
5402 static int *sched_domains_numa_distance
;
5403 static struct cpumask
***sched_domains_numa_masks
;
5404 static int sched_domains_curr_level
;
5406 static inline int sd_local_flags(int level
)
5408 if (sched_domains_numa_distance
[level
] > RECLAIM_DISTANCE
)
5411 return SD_BALANCE_EXEC
| SD_BALANCE_FORK
| SD_WAKE_AFFINE
;
5414 static struct sched_domain
*
5415 sd_numa_init(struct sched_domain_topology_level
*tl
, int cpu
)
5417 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
5418 int level
= tl
->numa_level
;
5419 int sd_weight
= cpumask_weight(
5420 sched_domains_numa_masks
[level
][cpu_to_node(cpu
)]);
5422 *sd
= (struct sched_domain
){
5423 .min_interval
= sd_weight
,
5424 .max_interval
= 2*sd_weight
,
5426 .imbalance_pct
= 125,
5427 .cache_nice_tries
= 2,
5434 .flags
= 1*SD_LOAD_BALANCE
5435 | 1*SD_BALANCE_NEWIDLE
5440 | 0*SD_SHARE_CPUPOWER
5441 | 0*SD_SHARE_PKG_RESOURCES
5443 | 0*SD_PREFER_SIBLING
5445 | sd_local_flags(level
)
5447 .last_balance
= jiffies
,
5448 .balance_interval
= sd_weight
,
5450 SD_INIT_NAME(sd
, NUMA
);
5451 sd
->private = &tl
->data
;
5454 * Ugly hack to pass state to sd_numa_mask()...
5456 sched_domains_curr_level
= tl
->numa_level
;
5461 static const struct cpumask
*sd_numa_mask(int cpu
)
5463 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
5466 static void sched_numa_warn(const char *str
)
5468 static int done
= false;
5476 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
5478 for (i
= 0; i
< nr_node_ids
; i
++) {
5479 printk(KERN_WARNING
" ");
5480 for (j
= 0; j
< nr_node_ids
; j
++)
5481 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
5482 printk(KERN_CONT
"\n");
5484 printk(KERN_WARNING
"\n");
5487 static bool find_numa_distance(int distance
)
5491 if (distance
== node_distance(0, 0))
5494 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
5495 if (sched_domains_numa_distance
[i
] == distance
)
5502 static void sched_init_numa(void)
5504 int next_distance
, curr_distance
= node_distance(0, 0);
5505 struct sched_domain_topology_level
*tl
;
5509 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
5510 if (!sched_domains_numa_distance
)
5514 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
5515 * unique distances in the node_distance() table.
5517 * Assumes node_distance(0,j) includes all distances in
5518 * node_distance(i,j) in order to avoid cubic time.
5520 next_distance
= curr_distance
;
5521 for (i
= 0; i
< nr_node_ids
; i
++) {
5522 for (j
= 0; j
< nr_node_ids
; j
++) {
5523 for (k
= 0; k
< nr_node_ids
; k
++) {
5524 int distance
= node_distance(i
, k
);
5526 if (distance
> curr_distance
&&
5527 (distance
< next_distance
||
5528 next_distance
== curr_distance
))
5529 next_distance
= distance
;
5532 * While not a strong assumption it would be nice to know
5533 * about cases where if node A is connected to B, B is not
5534 * equally connected to A.
5536 if (sched_debug() && node_distance(k
, i
) != distance
)
5537 sched_numa_warn("Node-distance not symmetric");
5539 if (sched_debug() && i
&& !find_numa_distance(distance
))
5540 sched_numa_warn("Node-0 not representative");
5542 if (next_distance
!= curr_distance
) {
5543 sched_domains_numa_distance
[level
++] = next_distance
;
5544 sched_domains_numa_levels
= level
;
5545 curr_distance
= next_distance
;
5550 * In case of sched_debug() we verify the above assumption.
5556 * 'level' contains the number of unique distances, excluding the
5557 * identity distance node_distance(i,i).
5559 * The sched_domains_numa_distance[] array includes the actual distance
5564 * Here, we should temporarily reset sched_domains_numa_levels to 0.
5565 * If it fails to allocate memory for array sched_domains_numa_masks[][],
5566 * the array will contain less then 'level' members. This could be
5567 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
5568 * in other functions.
5570 * We reset it to 'level' at the end of this function.
5572 sched_domains_numa_levels
= 0;
5574 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
5575 if (!sched_domains_numa_masks
)
5579 * Now for each level, construct a mask per node which contains all
5580 * cpus of nodes that are that many hops away from us.
5582 for (i
= 0; i
< level
; i
++) {
5583 sched_domains_numa_masks
[i
] =
5584 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
5585 if (!sched_domains_numa_masks
[i
])
5588 for (j
= 0; j
< nr_node_ids
; j
++) {
5589 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
5593 sched_domains_numa_masks
[i
][j
] = mask
;
5595 for (k
= 0; k
< nr_node_ids
; k
++) {
5596 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
5599 cpumask_or(mask
, mask
, cpumask_of_node(k
));
5604 tl
= kzalloc((ARRAY_SIZE(default_topology
) + level
) *
5605 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
5610 * Copy the default topology bits..
5612 for (i
= 0; default_topology
[i
].init
; i
++)
5613 tl
[i
] = default_topology
[i
];
5616 * .. and append 'j' levels of NUMA goodness.
5618 for (j
= 0; j
< level
; i
++, j
++) {
5619 tl
[i
] = (struct sched_domain_topology_level
){
5620 .init
= sd_numa_init
,
5621 .mask
= sd_numa_mask
,
5622 .flags
= SDTL_OVERLAP
,
5627 sched_domain_topology
= tl
;
5629 sched_domains_numa_levels
= level
;
5632 static void sched_domains_numa_masks_set(int cpu
)
5635 int node
= cpu_to_node(cpu
);
5637 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
5638 for (j
= 0; j
< nr_node_ids
; j
++) {
5639 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
5640 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
5645 static void sched_domains_numa_masks_clear(int cpu
)
5648 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
5649 for (j
= 0; j
< nr_node_ids
; j
++)
5650 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
5655 * Update sched_domains_numa_masks[level][node] array when new cpus
5658 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
5659 unsigned long action
,
5662 int cpu
= (long)hcpu
;
5664 switch (action
& ~CPU_TASKS_FROZEN
) {
5666 sched_domains_numa_masks_set(cpu
);
5670 sched_domains_numa_masks_clear(cpu
);
5680 static inline void sched_init_numa(void)
5684 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
5685 unsigned long action
,
5690 #endif /* CONFIG_NUMA */
5692 static int __sdt_alloc(const struct cpumask
*cpu_map
)
5694 struct sched_domain_topology_level
*tl
;
5697 for_each_sd_topology(tl
) {
5698 struct sd_data
*sdd
= &tl
->data
;
5700 sdd
->sd
= alloc_percpu(struct sched_domain
*);
5704 sdd
->sg
= alloc_percpu(struct sched_group
*);
5708 sdd
->sgp
= alloc_percpu(struct sched_group_power
*);
5712 for_each_cpu(j
, cpu_map
) {
5713 struct sched_domain
*sd
;
5714 struct sched_group
*sg
;
5715 struct sched_group_power
*sgp
;
5717 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
5718 GFP_KERNEL
, cpu_to_node(j
));
5722 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
5724 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5725 GFP_KERNEL
, cpu_to_node(j
));
5731 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
5733 sgp
= kzalloc_node(sizeof(struct sched_group_power
) + cpumask_size(),
5734 GFP_KERNEL
, cpu_to_node(j
));
5738 *per_cpu_ptr(sdd
->sgp
, j
) = sgp
;
5745 static void __sdt_free(const struct cpumask
*cpu_map
)
5747 struct sched_domain_topology_level
*tl
;
5750 for_each_sd_topology(tl
) {
5751 struct sd_data
*sdd
= &tl
->data
;
5753 for_each_cpu(j
, cpu_map
) {
5754 struct sched_domain
*sd
;
5757 sd
= *per_cpu_ptr(sdd
->sd
, j
);
5758 if (sd
&& (sd
->flags
& SD_OVERLAP
))
5759 free_sched_groups(sd
->groups
, 0);
5760 kfree(*per_cpu_ptr(sdd
->sd
, j
));
5764 kfree(*per_cpu_ptr(sdd
->sg
, j
));
5766 kfree(*per_cpu_ptr(sdd
->sgp
, j
));
5768 free_percpu(sdd
->sd
);
5770 free_percpu(sdd
->sg
);
5772 free_percpu(sdd
->sgp
);
5777 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
5778 const struct cpumask
*cpu_map
, struct sched_domain_attr
*attr
,
5779 struct sched_domain
*child
, int cpu
)
5781 struct sched_domain
*sd
= tl
->init(tl
, cpu
);
5785 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
5787 sd
->level
= child
->level
+ 1;
5788 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
5792 set_domain_attribute(sd
, attr
);
5798 * Build sched domains for a given set of cpus and attach the sched domains
5799 * to the individual cpus
5801 static int build_sched_domains(const struct cpumask
*cpu_map
,
5802 struct sched_domain_attr
*attr
)
5804 enum s_alloc alloc_state
;
5805 struct sched_domain
*sd
;
5807 int i
, ret
= -ENOMEM
;
5809 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
5810 if (alloc_state
!= sa_rootdomain
)
5813 /* Set up domains for cpus specified by the cpu_map. */
5814 for_each_cpu(i
, cpu_map
) {
5815 struct sched_domain_topology_level
*tl
;
5818 for_each_sd_topology(tl
) {
5819 sd
= build_sched_domain(tl
, cpu_map
, attr
, sd
, i
);
5820 if (tl
== sched_domain_topology
)
5821 *per_cpu_ptr(d
.sd
, i
) = sd
;
5822 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
5823 sd
->flags
|= SD_OVERLAP
;
5824 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
5829 /* Build the groups for the domains */
5830 for_each_cpu(i
, cpu_map
) {
5831 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
5832 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
5833 if (sd
->flags
& SD_OVERLAP
) {
5834 if (build_overlap_sched_groups(sd
, i
))
5837 if (build_sched_groups(sd
, i
))
5843 /* Calculate CPU power for physical packages and nodes */
5844 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
5845 if (!cpumask_test_cpu(i
, cpu_map
))
5848 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
5849 claim_allocations(i
, sd
);
5850 init_sched_groups_power(i
, sd
);
5854 /* Attach the domains */
5856 for_each_cpu(i
, cpu_map
) {
5857 sd
= *per_cpu_ptr(d
.sd
, i
);
5858 cpu_attach_domain(sd
, d
.rd
, i
);
5864 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
5868 static cpumask_var_t
*doms_cur
; /* current sched domains */
5869 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
5870 static struct sched_domain_attr
*dattr_cur
;
5871 /* attribues of custom domains in 'doms_cur' */
5874 * Special case: If a kmalloc of a doms_cur partition (array of
5875 * cpumask) fails, then fallback to a single sched domain,
5876 * as determined by the single cpumask fallback_doms.
5878 static cpumask_var_t fallback_doms
;
5881 * arch_update_cpu_topology lets virtualized architectures update the
5882 * cpu core maps. It is supposed to return 1 if the topology changed
5883 * or 0 if it stayed the same.
5885 int __attribute__((weak
)) arch_update_cpu_topology(void)
5890 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
5893 cpumask_var_t
*doms
;
5895 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
5898 for (i
= 0; i
< ndoms
; i
++) {
5899 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
5900 free_sched_domains(doms
, i
);
5907 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
5910 for (i
= 0; i
< ndoms
; i
++)
5911 free_cpumask_var(doms
[i
]);
5916 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5917 * For now this just excludes isolated cpus, but could be used to
5918 * exclude other special cases in the future.
5920 static int init_sched_domains(const struct cpumask
*cpu_map
)
5924 arch_update_cpu_topology();
5926 doms_cur
= alloc_sched_domains(ndoms_cur
);
5928 doms_cur
= &fallback_doms
;
5929 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
5930 err
= build_sched_domains(doms_cur
[0], NULL
);
5931 register_sched_domain_sysctl();
5937 * Detach sched domains from a group of cpus specified in cpu_map
5938 * These cpus will now be attached to the NULL domain
5940 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
5945 for_each_cpu(i
, cpu_map
)
5946 cpu_attach_domain(NULL
, &def_root_domain
, i
);
5950 /* handle null as "default" */
5951 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
5952 struct sched_domain_attr
*new, int idx_new
)
5954 struct sched_domain_attr tmp
;
5961 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
5962 new ? (new + idx_new
) : &tmp
,
5963 sizeof(struct sched_domain_attr
));
5967 * Partition sched domains as specified by the 'ndoms_new'
5968 * cpumasks in the array doms_new[] of cpumasks. This compares
5969 * doms_new[] to the current sched domain partitioning, doms_cur[].
5970 * It destroys each deleted domain and builds each new domain.
5972 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
5973 * The masks don't intersect (don't overlap.) We should setup one
5974 * sched domain for each mask. CPUs not in any of the cpumasks will
5975 * not be load balanced. If the same cpumask appears both in the
5976 * current 'doms_cur' domains and in the new 'doms_new', we can leave
5979 * The passed in 'doms_new' should be allocated using
5980 * alloc_sched_domains. This routine takes ownership of it and will
5981 * free_sched_domains it when done with it. If the caller failed the
5982 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
5983 * and partition_sched_domains() will fallback to the single partition
5984 * 'fallback_doms', it also forces the domains to be rebuilt.
5986 * If doms_new == NULL it will be replaced with cpu_online_mask.
5987 * ndoms_new == 0 is a special case for destroying existing domains,
5988 * and it will not create the default domain.
5990 * Call with hotplug lock held
5992 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
5993 struct sched_domain_attr
*dattr_new
)
5998 mutex_lock(&sched_domains_mutex
);
6000 /* always unregister in case we don't destroy any domains */
6001 unregister_sched_domain_sysctl();
6003 /* Let architecture update cpu core mappings. */
6004 new_topology
= arch_update_cpu_topology();
6006 n
= doms_new
? ndoms_new
: 0;
6008 /* Destroy deleted domains */
6009 for (i
= 0; i
< ndoms_cur
; i
++) {
6010 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6011 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
6012 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
6015 /* no match - a current sched domain not in new doms_new[] */
6016 detach_destroy_domains(doms_cur
[i
]);
6022 if (doms_new
== NULL
) {
6024 doms_new
= &fallback_doms
;
6025 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
6026 WARN_ON_ONCE(dattr_new
);
6029 /* Build new domains */
6030 for (i
= 0; i
< ndoms_new
; i
++) {
6031 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6032 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
6033 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
6036 /* no match - add a new doms_new */
6037 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
6042 /* Remember the new sched domains */
6043 if (doms_cur
!= &fallback_doms
)
6044 free_sched_domains(doms_cur
, ndoms_cur
);
6045 kfree(dattr_cur
); /* kfree(NULL) is safe */
6046 doms_cur
= doms_new
;
6047 dattr_cur
= dattr_new
;
6048 ndoms_cur
= ndoms_new
;
6050 register_sched_domain_sysctl();
6052 mutex_unlock(&sched_domains_mutex
);
6055 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
6058 * Update cpusets according to cpu_active mask. If cpusets are
6059 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6060 * around partition_sched_domains().
6062 * If we come here as part of a suspend/resume, don't touch cpusets because we
6063 * want to restore it back to its original state upon resume anyway.
6065 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
6069 case CPU_ONLINE_FROZEN
:
6070 case CPU_DOWN_FAILED_FROZEN
:
6073 * num_cpus_frozen tracks how many CPUs are involved in suspend
6074 * resume sequence. As long as this is not the last online
6075 * operation in the resume sequence, just build a single sched
6076 * domain, ignoring cpusets.
6079 if (likely(num_cpus_frozen
)) {
6080 partition_sched_domains(1, NULL
, NULL
);
6085 * This is the last CPU online operation. So fall through and
6086 * restore the original sched domains by considering the
6087 * cpuset configurations.
6091 case CPU_DOWN_FAILED
:
6092 cpuset_update_active_cpus(true);
6100 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
6104 case CPU_DOWN_PREPARE
:
6105 cpuset_update_active_cpus(false);
6107 case CPU_DOWN_PREPARE_FROZEN
:
6109 partition_sched_domains(1, NULL
, NULL
);
6117 void __init
sched_init_smp(void)
6119 cpumask_var_t non_isolated_cpus
;
6121 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
6122 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
6127 * There's no userspace yet to cause hotplug operations; hence all the
6128 * cpu masks are stable and all blatant races in the below code cannot
6131 mutex_lock(&sched_domains_mutex
);
6132 init_sched_domains(cpu_active_mask
);
6133 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
6134 if (cpumask_empty(non_isolated_cpus
))
6135 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
6136 mutex_unlock(&sched_domains_mutex
);
6138 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
6139 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
6140 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
6144 /* Move init over to a non-isolated CPU */
6145 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
6147 sched_init_granularity();
6148 free_cpumask_var(non_isolated_cpus
);
6150 init_sched_rt_class();
6153 void __init
sched_init_smp(void)
6155 sched_init_granularity();
6157 #endif /* CONFIG_SMP */
6159 const_debug
unsigned int sysctl_timer_migration
= 1;
6161 int in_sched_functions(unsigned long addr
)
6163 return in_lock_functions(addr
) ||
6164 (addr
>= (unsigned long)__sched_text_start
6165 && addr
< (unsigned long)__sched_text_end
);
6168 #ifdef CONFIG_CGROUP_SCHED
6170 * Default task group.
6171 * Every task in system belongs to this group at bootup.
6173 struct task_group root_task_group
;
6174 LIST_HEAD(task_groups
);
6177 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
6179 void __init
sched_init(void)
6182 unsigned long alloc_size
= 0, ptr
;
6184 #ifdef CONFIG_FAIR_GROUP_SCHED
6185 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6187 #ifdef CONFIG_RT_GROUP_SCHED
6188 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6190 #ifdef CONFIG_CPUMASK_OFFSTACK
6191 alloc_size
+= num_possible_cpus() * cpumask_size();
6194 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
6196 #ifdef CONFIG_FAIR_GROUP_SCHED
6197 root_task_group
.se
= (struct sched_entity
**)ptr
;
6198 ptr
+= nr_cpu_ids
* sizeof(void **);
6200 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
6201 ptr
+= nr_cpu_ids
* sizeof(void **);
6203 #endif /* CONFIG_FAIR_GROUP_SCHED */
6204 #ifdef CONFIG_RT_GROUP_SCHED
6205 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
6206 ptr
+= nr_cpu_ids
* sizeof(void **);
6208 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
6209 ptr
+= nr_cpu_ids
* sizeof(void **);
6211 #endif /* CONFIG_RT_GROUP_SCHED */
6212 #ifdef CONFIG_CPUMASK_OFFSTACK
6213 for_each_possible_cpu(i
) {
6214 per_cpu(load_balance_mask
, i
) = (void *)ptr
;
6215 ptr
+= cpumask_size();
6217 #endif /* CONFIG_CPUMASK_OFFSTACK */
6221 init_defrootdomain();
6224 init_rt_bandwidth(&def_rt_bandwidth
,
6225 global_rt_period(), global_rt_runtime());
6227 #ifdef CONFIG_RT_GROUP_SCHED
6228 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
6229 global_rt_period(), global_rt_runtime());
6230 #endif /* CONFIG_RT_GROUP_SCHED */
6232 #ifdef CONFIG_CGROUP_SCHED
6233 list_add(&root_task_group
.list
, &task_groups
);
6234 INIT_LIST_HEAD(&root_task_group
.children
);
6235 INIT_LIST_HEAD(&root_task_group
.siblings
);
6236 autogroup_init(&init_task
);
6238 #endif /* CONFIG_CGROUP_SCHED */
6240 for_each_possible_cpu(i
) {
6244 raw_spin_lock_init(&rq
->lock
);
6246 rq
->calc_load_active
= 0;
6247 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
6248 init_cfs_rq(&rq
->cfs
);
6249 init_rt_rq(&rq
->rt
, rq
);
6250 #ifdef CONFIG_FAIR_GROUP_SCHED
6251 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
6252 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6254 * How much cpu bandwidth does root_task_group get?
6256 * In case of task-groups formed thr' the cgroup filesystem, it
6257 * gets 100% of the cpu resources in the system. This overall
6258 * system cpu resource is divided among the tasks of
6259 * root_task_group and its child task-groups in a fair manner,
6260 * based on each entity's (task or task-group's) weight
6261 * (se->load.weight).
6263 * In other words, if root_task_group has 10 tasks of weight
6264 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6265 * then A0's share of the cpu resource is:
6267 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6269 * We achieve this by letting root_task_group's tasks sit
6270 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6272 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
6273 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
6274 #endif /* CONFIG_FAIR_GROUP_SCHED */
6276 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
6277 #ifdef CONFIG_RT_GROUP_SCHED
6278 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
6279 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
6282 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6283 rq
->cpu_load
[j
] = 0;
6285 rq
->last_load_update_tick
= jiffies
;
6290 rq
->cpu_power
= SCHED_POWER_SCALE
;
6291 rq
->post_schedule
= 0;
6292 rq
->active_balance
= 0;
6293 rq
->next_balance
= jiffies
;
6298 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
6299 rq
->max_idle_balance_cost
= sysctl_sched_migration_cost
;
6301 INIT_LIST_HEAD(&rq
->cfs_tasks
);
6303 rq_attach_root(rq
, &def_root_domain
);
6304 #ifdef CONFIG_NO_HZ_COMMON
6307 #ifdef CONFIG_NO_HZ_FULL
6308 rq
->last_sched_tick
= 0;
6312 atomic_set(&rq
->nr_iowait
, 0);
6315 set_load_weight(&init_task
);
6317 #ifdef CONFIG_PREEMPT_NOTIFIERS
6318 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6321 #ifdef CONFIG_RT_MUTEXES
6322 plist_head_init(&init_task
.pi_waiters
);
6326 * The boot idle thread does lazy MMU switching as well:
6328 atomic_inc(&init_mm
.mm_count
);
6329 enter_lazy_tlb(&init_mm
, current
);
6332 * Make us the idle thread. Technically, schedule() should not be
6333 * called from this thread, however somewhere below it might be,
6334 * but because we are the idle thread, we just pick up running again
6335 * when this runqueue becomes "idle".
6337 init_idle(current
, smp_processor_id());
6339 calc_load_update
= jiffies
+ LOAD_FREQ
;
6342 * During early bootup we pretend to be a normal task:
6344 current
->sched_class
= &fair_sched_class
;
6347 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
6348 /* May be allocated at isolcpus cmdline parse time */
6349 if (cpu_isolated_map
== NULL
)
6350 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
6351 idle_thread_set_boot_cpu();
6353 init_sched_fair_class();
6355 scheduler_running
= 1;
6358 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
6359 static inline int preempt_count_equals(int preempt_offset
)
6361 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
6363 return (nested
== preempt_offset
);
6366 void __might_sleep(const char *file
, int line
, int preempt_offset
)
6368 static unsigned long prev_jiffy
; /* ratelimiting */
6370 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
6371 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled()) ||
6372 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
6374 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6376 prev_jiffy
= jiffies
;
6379 "BUG: sleeping function called from invalid context at %s:%d\n",
6382 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
6383 in_atomic(), irqs_disabled(),
6384 current
->pid
, current
->comm
);
6386 debug_show_held_locks(current
);
6387 if (irqs_disabled())
6388 print_irqtrace_events(current
);
6391 EXPORT_SYMBOL(__might_sleep
);
6394 #ifdef CONFIG_MAGIC_SYSRQ
6395 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
6397 const struct sched_class
*prev_class
= p
->sched_class
;
6398 int old_prio
= p
->prio
;
6403 dequeue_task(rq
, p
, 0);
6404 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
6406 enqueue_task(rq
, p
, 0);
6407 resched_task(rq
->curr
);
6410 check_class_changed(rq
, p
, prev_class
, old_prio
);
6413 void normalize_rt_tasks(void)
6415 struct task_struct
*g
, *p
;
6416 unsigned long flags
;
6419 read_lock_irqsave(&tasklist_lock
, flags
);
6420 do_each_thread(g
, p
) {
6422 * Only normalize user tasks:
6427 p
->se
.exec_start
= 0;
6428 #ifdef CONFIG_SCHEDSTATS
6429 p
->se
.statistics
.wait_start
= 0;
6430 p
->se
.statistics
.sleep_start
= 0;
6431 p
->se
.statistics
.block_start
= 0;
6436 * Renice negative nice level userspace
6439 if (TASK_NICE(p
) < 0 && p
->mm
)
6440 set_user_nice(p
, 0);
6444 raw_spin_lock(&p
->pi_lock
);
6445 rq
= __task_rq_lock(p
);
6447 normalize_task(rq
, p
);
6449 __task_rq_unlock(rq
);
6450 raw_spin_unlock(&p
->pi_lock
);
6451 } while_each_thread(g
, p
);
6453 read_unlock_irqrestore(&tasklist_lock
, flags
);
6456 #endif /* CONFIG_MAGIC_SYSRQ */
6458 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
6460 * These functions are only useful for the IA64 MCA handling, or kdb.
6462 * They can only be called when the whole system has been
6463 * stopped - every CPU needs to be quiescent, and no scheduling
6464 * activity can take place. Using them for anything else would
6465 * be a serious bug, and as a result, they aren't even visible
6466 * under any other configuration.
6470 * curr_task - return the current task for a given cpu.
6471 * @cpu: the processor in question.
6473 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6475 * Return: The current task for @cpu.
6477 struct task_struct
*curr_task(int cpu
)
6479 return cpu_curr(cpu
);
6482 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
6486 * set_curr_task - set the current task for a given cpu.
6487 * @cpu: the processor in question.
6488 * @p: the task pointer to set.
6490 * Description: This function must only be used when non-maskable interrupts
6491 * are serviced on a separate stack. It allows the architecture to switch the
6492 * notion of the current task on a cpu in a non-blocking manner. This function
6493 * must be called with all CPU's synchronized, and interrupts disabled, the
6494 * and caller must save the original value of the current task (see
6495 * curr_task() above) and restore that value before reenabling interrupts and
6496 * re-starting the system.
6498 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6500 void set_curr_task(int cpu
, struct task_struct
*p
)
6507 #ifdef CONFIG_CGROUP_SCHED
6508 /* task_group_lock serializes the addition/removal of task groups */
6509 static DEFINE_SPINLOCK(task_group_lock
);
6511 static void free_sched_group(struct task_group
*tg
)
6513 free_fair_sched_group(tg
);
6514 free_rt_sched_group(tg
);
6519 /* allocate runqueue etc for a new task group */
6520 struct task_group
*sched_create_group(struct task_group
*parent
)
6522 struct task_group
*tg
;
6524 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
6526 return ERR_PTR(-ENOMEM
);
6528 if (!alloc_fair_sched_group(tg
, parent
))
6531 if (!alloc_rt_sched_group(tg
, parent
))
6537 free_sched_group(tg
);
6538 return ERR_PTR(-ENOMEM
);
6541 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
6543 unsigned long flags
;
6545 spin_lock_irqsave(&task_group_lock
, flags
);
6546 list_add_rcu(&tg
->list
, &task_groups
);
6548 WARN_ON(!parent
); /* root should already exist */
6550 tg
->parent
= parent
;
6551 INIT_LIST_HEAD(&tg
->children
);
6552 list_add_rcu(&tg
->siblings
, &parent
->children
);
6553 spin_unlock_irqrestore(&task_group_lock
, flags
);
6556 /* rcu callback to free various structures associated with a task group */
6557 static void free_sched_group_rcu(struct rcu_head
*rhp
)
6559 /* now it should be safe to free those cfs_rqs */
6560 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
6563 /* Destroy runqueue etc associated with a task group */
6564 void sched_destroy_group(struct task_group
*tg
)
6566 /* wait for possible concurrent references to cfs_rqs complete */
6567 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
6570 void sched_offline_group(struct task_group
*tg
)
6572 unsigned long flags
;
6575 /* end participation in shares distribution */
6576 for_each_possible_cpu(i
)
6577 unregister_fair_sched_group(tg
, i
);
6579 spin_lock_irqsave(&task_group_lock
, flags
);
6580 list_del_rcu(&tg
->list
);
6581 list_del_rcu(&tg
->siblings
);
6582 spin_unlock_irqrestore(&task_group_lock
, flags
);
6585 /* change task's runqueue when it moves between groups.
6586 * The caller of this function should have put the task in its new group
6587 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
6588 * reflect its new group.
6590 void sched_move_task(struct task_struct
*tsk
)
6592 struct task_group
*tg
;
6594 unsigned long flags
;
6597 rq
= task_rq_lock(tsk
, &flags
);
6599 running
= task_current(rq
, tsk
);
6603 dequeue_task(rq
, tsk
, 0);
6604 if (unlikely(running
))
6605 tsk
->sched_class
->put_prev_task(rq
, tsk
);
6607 tg
= container_of(task_css_check(tsk
, cpu_cgroup_subsys_id
,
6608 lockdep_is_held(&tsk
->sighand
->siglock
)),
6609 struct task_group
, css
);
6610 tg
= autogroup_task_group(tsk
, tg
);
6611 tsk
->sched_task_group
= tg
;
6613 #ifdef CONFIG_FAIR_GROUP_SCHED
6614 if (tsk
->sched_class
->task_move_group
)
6615 tsk
->sched_class
->task_move_group(tsk
, on_rq
);
6618 set_task_rq(tsk
, task_cpu(tsk
));
6620 if (unlikely(running
))
6621 tsk
->sched_class
->set_curr_task(rq
);
6623 enqueue_task(rq
, tsk
, 0);
6625 task_rq_unlock(rq
, tsk
, &flags
);
6627 #endif /* CONFIG_CGROUP_SCHED */
6629 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
6630 static unsigned long to_ratio(u64 period
, u64 runtime
)
6632 if (runtime
== RUNTIME_INF
)
6635 return div64_u64(runtime
<< 20, period
);
6639 #ifdef CONFIG_RT_GROUP_SCHED
6641 * Ensure that the real time constraints are schedulable.
6643 static DEFINE_MUTEX(rt_constraints_mutex
);
6645 /* Must be called with tasklist_lock held */
6646 static inline int tg_has_rt_tasks(struct task_group
*tg
)
6648 struct task_struct
*g
, *p
;
6650 do_each_thread(g
, p
) {
6651 if (rt_task(p
) && task_rq(p
)->rt
.tg
== tg
)
6653 } while_each_thread(g
, p
);
6658 struct rt_schedulable_data
{
6659 struct task_group
*tg
;
6664 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
6666 struct rt_schedulable_data
*d
= data
;
6667 struct task_group
*child
;
6668 unsigned long total
, sum
= 0;
6669 u64 period
, runtime
;
6671 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
6672 runtime
= tg
->rt_bandwidth
.rt_runtime
;
6675 period
= d
->rt_period
;
6676 runtime
= d
->rt_runtime
;
6680 * Cannot have more runtime than the period.
6682 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
6686 * Ensure we don't starve existing RT tasks.
6688 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
6691 total
= to_ratio(period
, runtime
);
6694 * Nobody can have more than the global setting allows.
6696 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
6700 * The sum of our children's runtime should not exceed our own.
6702 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
6703 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
6704 runtime
= child
->rt_bandwidth
.rt_runtime
;
6706 if (child
== d
->tg
) {
6707 period
= d
->rt_period
;
6708 runtime
= d
->rt_runtime
;
6711 sum
+= to_ratio(period
, runtime
);
6720 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
6724 struct rt_schedulable_data data
= {
6726 .rt_period
= period
,
6727 .rt_runtime
= runtime
,
6731 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
6737 static int tg_set_rt_bandwidth(struct task_group
*tg
,
6738 u64 rt_period
, u64 rt_runtime
)
6742 mutex_lock(&rt_constraints_mutex
);
6743 read_lock(&tasklist_lock
);
6744 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
6748 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
6749 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
6750 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
6752 for_each_possible_cpu(i
) {
6753 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
6755 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
6756 rt_rq
->rt_runtime
= rt_runtime
;
6757 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
6759 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
6761 read_unlock(&tasklist_lock
);
6762 mutex_unlock(&rt_constraints_mutex
);
6767 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
6769 u64 rt_runtime
, rt_period
;
6771 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
6772 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
6773 if (rt_runtime_us
< 0)
6774 rt_runtime
= RUNTIME_INF
;
6776 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
6779 static long sched_group_rt_runtime(struct task_group
*tg
)
6783 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
6786 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
6787 do_div(rt_runtime_us
, NSEC_PER_USEC
);
6788 return rt_runtime_us
;
6791 static int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
6793 u64 rt_runtime
, rt_period
;
6795 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
6796 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
6801 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
6804 static long sched_group_rt_period(struct task_group
*tg
)
6808 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
6809 do_div(rt_period_us
, NSEC_PER_USEC
);
6810 return rt_period_us
;
6813 static int sched_rt_global_constraints(void)
6815 u64 runtime
, period
;
6818 if (sysctl_sched_rt_period
<= 0)
6821 runtime
= global_rt_runtime();
6822 period
= global_rt_period();
6825 * Sanity check on the sysctl variables.
6827 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
6830 mutex_lock(&rt_constraints_mutex
);
6831 read_lock(&tasklist_lock
);
6832 ret
= __rt_schedulable(NULL
, 0, 0);
6833 read_unlock(&tasklist_lock
);
6834 mutex_unlock(&rt_constraints_mutex
);
6839 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
6841 /* Don't accept realtime tasks when there is no way for them to run */
6842 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
6848 #else /* !CONFIG_RT_GROUP_SCHED */
6849 static int sched_rt_global_constraints(void)
6851 unsigned long flags
;
6854 if (sysctl_sched_rt_period
<= 0)
6858 * There's always some RT tasks in the root group
6859 * -- migration, kstopmachine etc..
6861 if (sysctl_sched_rt_runtime
== 0)
6864 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
6865 for_each_possible_cpu(i
) {
6866 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
6868 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
6869 rt_rq
->rt_runtime
= global_rt_runtime();
6870 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
6872 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
6876 #endif /* CONFIG_RT_GROUP_SCHED */
6878 int sched_rr_handler(struct ctl_table
*table
, int write
,
6879 void __user
*buffer
, size_t *lenp
,
6883 static DEFINE_MUTEX(mutex
);
6886 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
6887 /* make sure that internally we keep jiffies */
6888 /* also, writing zero resets timeslice to default */
6889 if (!ret
&& write
) {
6890 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
6891 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
6893 mutex_unlock(&mutex
);
6897 int sched_rt_handler(struct ctl_table
*table
, int write
,
6898 void __user
*buffer
, size_t *lenp
,
6902 int old_period
, old_runtime
;
6903 static DEFINE_MUTEX(mutex
);
6906 old_period
= sysctl_sched_rt_period
;
6907 old_runtime
= sysctl_sched_rt_runtime
;
6909 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
6911 if (!ret
&& write
) {
6912 ret
= sched_rt_global_constraints();
6914 sysctl_sched_rt_period
= old_period
;
6915 sysctl_sched_rt_runtime
= old_runtime
;
6917 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
6918 def_rt_bandwidth
.rt_period
=
6919 ns_to_ktime(global_rt_period());
6922 mutex_unlock(&mutex
);
6927 #ifdef CONFIG_CGROUP_SCHED
6929 static inline struct task_group
*css_tg(struct cgroup_subsys_state
*css
)
6931 return css
? container_of(css
, struct task_group
, css
) : NULL
;
6934 static struct cgroup_subsys_state
*
6935 cpu_cgroup_css_alloc(struct cgroup_subsys_state
*parent_css
)
6937 struct task_group
*parent
= css_tg(parent_css
);
6938 struct task_group
*tg
;
6941 /* This is early initialization for the top cgroup */
6942 return &root_task_group
.css
;
6945 tg
= sched_create_group(parent
);
6947 return ERR_PTR(-ENOMEM
);
6952 static int cpu_cgroup_css_online(struct cgroup_subsys_state
*css
)
6954 struct task_group
*tg
= css_tg(css
);
6955 struct task_group
*parent
= css_tg(css_parent(css
));
6958 sched_online_group(tg
, parent
);
6962 static void cpu_cgroup_css_free(struct cgroup_subsys_state
*css
)
6964 struct task_group
*tg
= css_tg(css
);
6966 sched_destroy_group(tg
);
6969 static void cpu_cgroup_css_offline(struct cgroup_subsys_state
*css
)
6971 struct task_group
*tg
= css_tg(css
);
6973 sched_offline_group(tg
);
6976 static int cpu_cgroup_can_attach(struct cgroup_subsys_state
*css
,
6977 struct cgroup_taskset
*tset
)
6979 struct task_struct
*task
;
6981 cgroup_taskset_for_each(task
, css
, tset
) {
6982 #ifdef CONFIG_RT_GROUP_SCHED
6983 if (!sched_rt_can_attach(css_tg(css
), task
))
6986 /* We don't support RT-tasks being in separate groups */
6987 if (task
->sched_class
!= &fair_sched_class
)
6994 static void cpu_cgroup_attach(struct cgroup_subsys_state
*css
,
6995 struct cgroup_taskset
*tset
)
6997 struct task_struct
*task
;
6999 cgroup_taskset_for_each(task
, css
, tset
)
7000 sched_move_task(task
);
7003 static void cpu_cgroup_exit(struct cgroup_subsys_state
*css
,
7004 struct cgroup_subsys_state
*old_css
,
7005 struct task_struct
*task
)
7008 * cgroup_exit() is called in the copy_process() failure path.
7009 * Ignore this case since the task hasn't ran yet, this avoids
7010 * trying to poke a half freed task state from generic code.
7012 if (!(task
->flags
& PF_EXITING
))
7015 sched_move_task(task
);
7018 #ifdef CONFIG_FAIR_GROUP_SCHED
7019 static int cpu_shares_write_u64(struct cgroup_subsys_state
*css
,
7020 struct cftype
*cftype
, u64 shareval
)
7022 return sched_group_set_shares(css_tg(css
), scale_load(shareval
));
7025 static u64
cpu_shares_read_u64(struct cgroup_subsys_state
*css
,
7028 struct task_group
*tg
= css_tg(css
);
7030 return (u64
) scale_load_down(tg
->shares
);
7033 #ifdef CONFIG_CFS_BANDWIDTH
7034 static DEFINE_MUTEX(cfs_constraints_mutex
);
7036 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
7037 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
7039 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
7041 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
7043 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
7044 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7046 if (tg
== &root_task_group
)
7050 * Ensure we have at some amount of bandwidth every period. This is
7051 * to prevent reaching a state of large arrears when throttled via
7052 * entity_tick() resulting in prolonged exit starvation.
7054 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
7058 * Likewise, bound things on the otherside by preventing insane quota
7059 * periods. This also allows us to normalize in computing quota
7062 if (period
> max_cfs_quota_period
)
7065 mutex_lock(&cfs_constraints_mutex
);
7066 ret
= __cfs_schedulable(tg
, period
, quota
);
7070 runtime_enabled
= quota
!= RUNTIME_INF
;
7071 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
7073 * If we need to toggle cfs_bandwidth_used, off->on must occur
7074 * before making related changes, and on->off must occur afterwards
7076 if (runtime_enabled
&& !runtime_was_enabled
)
7077 cfs_bandwidth_usage_inc();
7078 raw_spin_lock_irq(&cfs_b
->lock
);
7079 cfs_b
->period
= ns_to_ktime(period
);
7080 cfs_b
->quota
= quota
;
7082 __refill_cfs_bandwidth_runtime(cfs_b
);
7083 /* restart the period timer (if active) to handle new period expiry */
7084 if (runtime_enabled
&& cfs_b
->timer_active
) {
7085 /* force a reprogram */
7086 cfs_b
->timer_active
= 0;
7087 __start_cfs_bandwidth(cfs_b
);
7089 raw_spin_unlock_irq(&cfs_b
->lock
);
7091 for_each_possible_cpu(i
) {
7092 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
7093 struct rq
*rq
= cfs_rq
->rq
;
7095 raw_spin_lock_irq(&rq
->lock
);
7096 cfs_rq
->runtime_enabled
= runtime_enabled
;
7097 cfs_rq
->runtime_remaining
= 0;
7099 if (cfs_rq
->throttled
)
7100 unthrottle_cfs_rq(cfs_rq
);
7101 raw_spin_unlock_irq(&rq
->lock
);
7103 if (runtime_was_enabled
&& !runtime_enabled
)
7104 cfs_bandwidth_usage_dec();
7106 mutex_unlock(&cfs_constraints_mutex
);
7111 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
7115 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7116 if (cfs_quota_us
< 0)
7117 quota
= RUNTIME_INF
;
7119 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
7121 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7124 long tg_get_cfs_quota(struct task_group
*tg
)
7128 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
7131 quota_us
= tg
->cfs_bandwidth
.quota
;
7132 do_div(quota_us
, NSEC_PER_USEC
);
7137 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
7141 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
7142 quota
= tg
->cfs_bandwidth
.quota
;
7144 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7147 long tg_get_cfs_period(struct task_group
*tg
)
7151 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7152 do_div(cfs_period_us
, NSEC_PER_USEC
);
7154 return cfs_period_us
;
7157 static s64
cpu_cfs_quota_read_s64(struct cgroup_subsys_state
*css
,
7160 return tg_get_cfs_quota(css_tg(css
));
7163 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state
*css
,
7164 struct cftype
*cftype
, s64 cfs_quota_us
)
7166 return tg_set_cfs_quota(css_tg(css
), cfs_quota_us
);
7169 static u64
cpu_cfs_period_read_u64(struct cgroup_subsys_state
*css
,
7172 return tg_get_cfs_period(css_tg(css
));
7175 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state
*css
,
7176 struct cftype
*cftype
, u64 cfs_period_us
)
7178 return tg_set_cfs_period(css_tg(css
), cfs_period_us
);
7181 struct cfs_schedulable_data
{
7182 struct task_group
*tg
;
7187 * normalize group quota/period to be quota/max_period
7188 * note: units are usecs
7190 static u64
normalize_cfs_quota(struct task_group
*tg
,
7191 struct cfs_schedulable_data
*d
)
7199 period
= tg_get_cfs_period(tg
);
7200 quota
= tg_get_cfs_quota(tg
);
7203 /* note: these should typically be equivalent */
7204 if (quota
== RUNTIME_INF
|| quota
== -1)
7207 return to_ratio(period
, quota
);
7210 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
7212 struct cfs_schedulable_data
*d
= data
;
7213 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7214 s64 quota
= 0, parent_quota
= -1;
7217 quota
= RUNTIME_INF
;
7219 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
7221 quota
= normalize_cfs_quota(tg
, d
);
7222 parent_quota
= parent_b
->hierarchal_quota
;
7225 * ensure max(child_quota) <= parent_quota, inherit when no
7228 if (quota
== RUNTIME_INF
)
7229 quota
= parent_quota
;
7230 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
7233 cfs_b
->hierarchal_quota
= quota
;
7238 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
7241 struct cfs_schedulable_data data
= {
7247 if (quota
!= RUNTIME_INF
) {
7248 do_div(data
.period
, NSEC_PER_USEC
);
7249 do_div(data
.quota
, NSEC_PER_USEC
);
7253 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
7259 static int cpu_stats_show(struct cgroup_subsys_state
*css
, struct cftype
*cft
,
7260 struct cgroup_map_cb
*cb
)
7262 struct task_group
*tg
= css_tg(css
);
7263 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7265 cb
->fill(cb
, "nr_periods", cfs_b
->nr_periods
);
7266 cb
->fill(cb
, "nr_throttled", cfs_b
->nr_throttled
);
7267 cb
->fill(cb
, "throttled_time", cfs_b
->throttled_time
);
7271 #endif /* CONFIG_CFS_BANDWIDTH */
7272 #endif /* CONFIG_FAIR_GROUP_SCHED */
7274 #ifdef CONFIG_RT_GROUP_SCHED
7275 static int cpu_rt_runtime_write(struct cgroup_subsys_state
*css
,
7276 struct cftype
*cft
, s64 val
)
7278 return sched_group_set_rt_runtime(css_tg(css
), val
);
7281 static s64
cpu_rt_runtime_read(struct cgroup_subsys_state
*css
,
7284 return sched_group_rt_runtime(css_tg(css
));
7287 static int cpu_rt_period_write_uint(struct cgroup_subsys_state
*css
,
7288 struct cftype
*cftype
, u64 rt_period_us
)
7290 return sched_group_set_rt_period(css_tg(css
), rt_period_us
);
7293 static u64
cpu_rt_period_read_uint(struct cgroup_subsys_state
*css
,
7296 return sched_group_rt_period(css_tg(css
));
7298 #endif /* CONFIG_RT_GROUP_SCHED */
7300 static struct cftype cpu_files
[] = {
7301 #ifdef CONFIG_FAIR_GROUP_SCHED
7304 .read_u64
= cpu_shares_read_u64
,
7305 .write_u64
= cpu_shares_write_u64
,
7308 #ifdef CONFIG_CFS_BANDWIDTH
7310 .name
= "cfs_quota_us",
7311 .read_s64
= cpu_cfs_quota_read_s64
,
7312 .write_s64
= cpu_cfs_quota_write_s64
,
7315 .name
= "cfs_period_us",
7316 .read_u64
= cpu_cfs_period_read_u64
,
7317 .write_u64
= cpu_cfs_period_write_u64
,
7321 .read_map
= cpu_stats_show
,
7324 #ifdef CONFIG_RT_GROUP_SCHED
7326 .name
= "rt_runtime_us",
7327 .read_s64
= cpu_rt_runtime_read
,
7328 .write_s64
= cpu_rt_runtime_write
,
7331 .name
= "rt_period_us",
7332 .read_u64
= cpu_rt_period_read_uint
,
7333 .write_u64
= cpu_rt_period_write_uint
,
7339 struct cgroup_subsys cpu_cgroup_subsys
= {
7341 .css_alloc
= cpu_cgroup_css_alloc
,
7342 .css_free
= cpu_cgroup_css_free
,
7343 .css_online
= cpu_cgroup_css_online
,
7344 .css_offline
= cpu_cgroup_css_offline
,
7345 .can_attach
= cpu_cgroup_can_attach
,
7346 .attach
= cpu_cgroup_attach
,
7347 .exit
= cpu_cgroup_exit
,
7348 .subsys_id
= cpu_cgroup_subsys_id
,
7349 .base_cftypes
= cpu_files
,
7353 #endif /* CONFIG_CGROUP_SCHED */
7355 void dump_cpu_task(int cpu
)
7357 pr_info("Task dump for CPU %d:\n", cpu
);
7358 sched_show_task(cpu_curr(cpu
));