4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <asm/mmu_context.h>
36 #include <linux/interrupt.h>
37 #include <linux/capability.h>
38 #include <linux/completion.h>
39 #include <linux/kernel_stat.h>
40 #include <linux/debug_locks.h>
41 #include <linux/perf_event.h>
42 #include <linux/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/proc_fs.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/unistd.h>
66 #include <linux/pagemap.h>
67 #include <linux/hrtimer.h>
68 #include <linux/tick.h>
69 #include <linux/debugfs.h>
70 #include <linux/ctype.h>
71 #include <linux/ftrace.h>
72 #include <linux/slab.h>
73 #include <linux/init_task.h>
74 #include <linux/binfmts.h>
75 #include <linux/context_tracking.h>
77 #include <asm/switch_to.h>
79 #include <asm/irq_regs.h>
80 #include <asm/mutex.h>
81 #ifdef CONFIG_PARAVIRT
82 #include <asm/paravirt.h>
86 #include "../workqueue_internal.h"
87 #include "../smpboot.h"
89 #define CREATE_TRACE_POINTS
90 #include <trace/events/sched.h>
92 void start_bandwidth_timer(struct hrtimer
*period_timer
, ktime_t period
)
95 ktime_t soft
, hard
, now
;
98 if (hrtimer_active(period_timer
))
101 now
= hrtimer_cb_get_time(period_timer
);
102 hrtimer_forward(period_timer
, now
, period
);
104 soft
= hrtimer_get_softexpires(period_timer
);
105 hard
= hrtimer_get_expires(period_timer
);
106 delta
= ktime_to_ns(ktime_sub(hard
, soft
));
107 __hrtimer_start_range_ns(period_timer
, soft
, delta
,
108 HRTIMER_MODE_ABS_PINNED
, 0);
112 DEFINE_MUTEX(sched_domains_mutex
);
113 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
115 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
117 void update_rq_clock(struct rq
*rq
)
121 if (rq
->skip_clock_update
> 0)
124 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
126 update_rq_clock_task(rq
, delta
);
130 * Debugging: various feature bits
133 #define SCHED_FEAT(name, enabled) \
134 (1UL << __SCHED_FEAT_##name) * enabled |
136 const_debug
unsigned int sysctl_sched_features
=
137 #include "features.h"
142 #ifdef CONFIG_SCHED_DEBUG
143 #define SCHED_FEAT(name, enabled) \
146 static const char * const sched_feat_names
[] = {
147 #include "features.h"
152 static int sched_feat_show(struct seq_file
*m
, void *v
)
156 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
157 if (!(sysctl_sched_features
& (1UL << i
)))
159 seq_printf(m
, "%s ", sched_feat_names
[i
]);
166 #ifdef HAVE_JUMP_LABEL
168 #define jump_label_key__true STATIC_KEY_INIT_TRUE
169 #define jump_label_key__false STATIC_KEY_INIT_FALSE
171 #define SCHED_FEAT(name, enabled) \
172 jump_label_key__##enabled ,
174 struct static_key sched_feat_keys
[__SCHED_FEAT_NR
] = {
175 #include "features.h"
180 static void sched_feat_disable(int i
)
182 if (static_key_enabled(&sched_feat_keys
[i
]))
183 static_key_slow_dec(&sched_feat_keys
[i
]);
186 static void sched_feat_enable(int i
)
188 if (!static_key_enabled(&sched_feat_keys
[i
]))
189 static_key_slow_inc(&sched_feat_keys
[i
]);
192 static void sched_feat_disable(int i
) { };
193 static void sched_feat_enable(int i
) { };
194 #endif /* HAVE_JUMP_LABEL */
196 static int sched_feat_set(char *cmp
)
201 if (strncmp(cmp
, "NO_", 3) == 0) {
206 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
207 if (strcmp(cmp
, sched_feat_names
[i
]) == 0) {
209 sysctl_sched_features
&= ~(1UL << i
);
210 sched_feat_disable(i
);
212 sysctl_sched_features
|= (1UL << i
);
213 sched_feat_enable(i
);
223 sched_feat_write(struct file
*filp
, const char __user
*ubuf
,
224 size_t cnt
, loff_t
*ppos
)
233 if (copy_from_user(&buf
, ubuf
, cnt
))
239 i
= sched_feat_set(cmp
);
240 if (i
== __SCHED_FEAT_NR
)
248 static int sched_feat_open(struct inode
*inode
, struct file
*filp
)
250 return single_open(filp
, sched_feat_show
, NULL
);
253 static const struct file_operations sched_feat_fops
= {
254 .open
= sched_feat_open
,
255 .write
= sched_feat_write
,
258 .release
= single_release
,
261 static __init
int sched_init_debug(void)
263 debugfs_create_file("sched_features", 0644, NULL
, NULL
,
268 late_initcall(sched_init_debug
);
269 #endif /* CONFIG_SCHED_DEBUG */
272 * Number of tasks to iterate in a single balance run.
273 * Limited because this is done with IRQs disabled.
275 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
278 * period over which we average the RT time consumption, measured
283 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
286 * period over which we measure -rt task cpu usage in us.
289 unsigned int sysctl_sched_rt_period
= 1000000;
291 __read_mostly
int scheduler_running
;
294 * part of the period that we allow rt tasks to run in us.
297 int sysctl_sched_rt_runtime
= 950000;
302 * __task_rq_lock - lock the rq @p resides on.
304 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
309 lockdep_assert_held(&p
->pi_lock
);
313 raw_spin_lock(&rq
->lock
);
314 if (likely(rq
== task_rq(p
)))
316 raw_spin_unlock(&rq
->lock
);
321 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
323 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
324 __acquires(p
->pi_lock
)
330 raw_spin_lock_irqsave(&p
->pi_lock
, *flags
);
332 raw_spin_lock(&rq
->lock
);
333 if (likely(rq
== task_rq(p
)))
335 raw_spin_unlock(&rq
->lock
);
336 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
340 static void __task_rq_unlock(struct rq
*rq
)
343 raw_spin_unlock(&rq
->lock
);
347 task_rq_unlock(struct rq
*rq
, struct task_struct
*p
, unsigned long *flags
)
349 __releases(p
->pi_lock
)
351 raw_spin_unlock(&rq
->lock
);
352 raw_spin_unlock_irqrestore(&p
->pi_lock
, *flags
);
356 * this_rq_lock - lock this runqueue and disable interrupts.
358 static struct rq
*this_rq_lock(void)
365 raw_spin_lock(&rq
->lock
);
370 #ifdef CONFIG_SCHED_HRTICK
372 * Use HR-timers to deliver accurate preemption points.
374 * Its all a bit involved since we cannot program an hrt while holding the
375 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
378 * When we get rescheduled we reprogram the hrtick_timer outside of the
382 static void hrtick_clear(struct rq
*rq
)
384 if (hrtimer_active(&rq
->hrtick_timer
))
385 hrtimer_cancel(&rq
->hrtick_timer
);
389 * High-resolution timer tick.
390 * Runs from hardirq context with interrupts disabled.
392 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
394 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
396 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
398 raw_spin_lock(&rq
->lock
);
400 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
401 raw_spin_unlock(&rq
->lock
);
403 return HRTIMER_NORESTART
;
408 * called from hardirq (IPI) context
410 static void __hrtick_start(void *arg
)
414 raw_spin_lock(&rq
->lock
);
415 hrtimer_restart(&rq
->hrtick_timer
);
416 rq
->hrtick_csd_pending
= 0;
417 raw_spin_unlock(&rq
->lock
);
421 * Called to set the hrtick timer state.
423 * called with rq->lock held and irqs disabled
425 void hrtick_start(struct rq
*rq
, u64 delay
)
427 struct hrtimer
*timer
= &rq
->hrtick_timer
;
428 ktime_t time
= ktime_add_ns(timer
->base
->get_time(), delay
);
430 hrtimer_set_expires(timer
, time
);
432 if (rq
== this_rq()) {
433 hrtimer_restart(timer
);
434 } else if (!rq
->hrtick_csd_pending
) {
435 __smp_call_function_single(cpu_of(rq
), &rq
->hrtick_csd
, 0);
436 rq
->hrtick_csd_pending
= 1;
441 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
443 int cpu
= (int)(long)hcpu
;
446 case CPU_UP_CANCELED
:
447 case CPU_UP_CANCELED_FROZEN
:
448 case CPU_DOWN_PREPARE
:
449 case CPU_DOWN_PREPARE_FROZEN
:
451 case CPU_DEAD_FROZEN
:
452 hrtick_clear(cpu_rq(cpu
));
459 static __init
void init_hrtick(void)
461 hotcpu_notifier(hotplug_hrtick
, 0);
465 * Called to set the hrtick timer state.
467 * called with rq->lock held and irqs disabled
469 void hrtick_start(struct rq
*rq
, u64 delay
)
471 __hrtimer_start_range_ns(&rq
->hrtick_timer
, ns_to_ktime(delay
), 0,
472 HRTIMER_MODE_REL_PINNED
, 0);
475 static inline void init_hrtick(void)
478 #endif /* CONFIG_SMP */
480 static void init_rq_hrtick(struct rq
*rq
)
483 rq
->hrtick_csd_pending
= 0;
485 rq
->hrtick_csd
.flags
= 0;
486 rq
->hrtick_csd
.func
= __hrtick_start
;
487 rq
->hrtick_csd
.info
= rq
;
490 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
491 rq
->hrtick_timer
.function
= hrtick
;
493 #else /* CONFIG_SCHED_HRTICK */
494 static inline void hrtick_clear(struct rq
*rq
)
498 static inline void init_rq_hrtick(struct rq
*rq
)
502 static inline void init_hrtick(void)
505 #endif /* CONFIG_SCHED_HRTICK */
508 * resched_task - mark a task 'to be rescheduled now'.
510 * On UP this means the setting of the need_resched flag, on SMP it
511 * might also involve a cross-CPU call to trigger the scheduler on
515 void resched_task(struct task_struct
*p
)
519 assert_raw_spin_locked(&task_rq(p
)->lock
);
521 if (test_tsk_need_resched(p
))
524 set_tsk_need_resched(p
);
527 if (cpu
== smp_processor_id())
530 /* NEED_RESCHED must be visible before we test polling */
532 if (!tsk_is_polling(p
))
533 smp_send_reschedule(cpu
);
536 void resched_cpu(int cpu
)
538 struct rq
*rq
= cpu_rq(cpu
);
541 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
543 resched_task(cpu_curr(cpu
));
544 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
547 #ifdef CONFIG_NO_HZ_COMMON
549 * In the semi idle case, use the nearest busy cpu for migrating timers
550 * from an idle cpu. This is good for power-savings.
552 * We don't do similar optimization for completely idle system, as
553 * selecting an idle cpu will add more delays to the timers than intended
554 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
556 int get_nohz_timer_target(void)
558 int cpu
= smp_processor_id();
560 struct sched_domain
*sd
;
563 for_each_domain(cpu
, sd
) {
564 for_each_cpu(i
, sched_domain_span(sd
)) {
576 * When add_timer_on() enqueues a timer into the timer wheel of an
577 * idle CPU then this timer might expire before the next timer event
578 * which is scheduled to wake up that CPU. In case of a completely
579 * idle system the next event might even be infinite time into the
580 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
581 * leaves the inner idle loop so the newly added timer is taken into
582 * account when the CPU goes back to idle and evaluates the timer
583 * wheel for the next timer event.
585 static void wake_up_idle_cpu(int cpu
)
587 struct rq
*rq
= cpu_rq(cpu
);
589 if (cpu
== smp_processor_id())
593 * This is safe, as this function is called with the timer
594 * wheel base lock of (cpu) held. When the CPU is on the way
595 * to idle and has not yet set rq->curr to idle then it will
596 * be serialized on the timer wheel base lock and take the new
597 * timer into account automatically.
599 if (rq
->curr
!= rq
->idle
)
603 * We can set TIF_RESCHED on the idle task of the other CPU
604 * lockless. The worst case is that the other CPU runs the
605 * idle task through an additional NOOP schedule()
607 set_tsk_need_resched(rq
->idle
);
609 /* NEED_RESCHED must be visible before we test polling */
611 if (!tsk_is_polling(rq
->idle
))
612 smp_send_reschedule(cpu
);
615 static bool wake_up_full_nohz_cpu(int cpu
)
617 if (tick_nohz_full_cpu(cpu
)) {
618 if (cpu
!= smp_processor_id() ||
619 tick_nohz_tick_stopped())
620 smp_send_reschedule(cpu
);
627 void wake_up_nohz_cpu(int cpu
)
629 if (!wake_up_full_nohz_cpu(cpu
))
630 wake_up_idle_cpu(cpu
);
633 static inline bool got_nohz_idle_kick(void)
635 int cpu
= smp_processor_id();
636 return idle_cpu(cpu
) && test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
639 #else /* CONFIG_NO_HZ_COMMON */
641 static inline bool got_nohz_idle_kick(void)
646 #endif /* CONFIG_NO_HZ_COMMON */
648 #ifdef CONFIG_NO_HZ_FULL
649 bool sched_can_stop_tick(void)
655 /* Make sure rq->nr_running update is visible after the IPI */
658 /* More than one running task need preemption */
659 if (rq
->nr_running
> 1)
664 #endif /* CONFIG_NO_HZ_FULL */
666 void sched_avg_update(struct rq
*rq
)
668 s64 period
= sched_avg_period();
670 while ((s64
)(rq
->clock
- rq
->age_stamp
) > period
) {
672 * Inline assembly required to prevent the compiler
673 * optimising this loop into a divmod call.
674 * See __iter_div_u64_rem() for another example of this.
676 asm("" : "+rm" (rq
->age_stamp
));
677 rq
->age_stamp
+= period
;
682 #else /* !CONFIG_SMP */
683 void resched_task(struct task_struct
*p
)
685 assert_raw_spin_locked(&task_rq(p
)->lock
);
686 set_tsk_need_resched(p
);
688 #endif /* CONFIG_SMP */
690 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
691 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
693 * Iterate task_group tree rooted at *from, calling @down when first entering a
694 * node and @up when leaving it for the final time.
696 * Caller must hold rcu_lock or sufficient equivalent.
698 int walk_tg_tree_from(struct task_group
*from
,
699 tg_visitor down
, tg_visitor up
, void *data
)
701 struct task_group
*parent
, *child
;
707 ret
= (*down
)(parent
, data
);
710 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
717 ret
= (*up
)(parent
, data
);
718 if (ret
|| parent
== from
)
722 parent
= parent
->parent
;
729 int tg_nop(struct task_group
*tg
, void *data
)
735 static void set_load_weight(struct task_struct
*p
)
737 int prio
= p
->static_prio
- MAX_RT_PRIO
;
738 struct load_weight
*load
= &p
->se
.load
;
741 * SCHED_IDLE tasks get minimal weight:
743 if (p
->policy
== SCHED_IDLE
) {
744 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
745 load
->inv_weight
= WMULT_IDLEPRIO
;
749 load
->weight
= scale_load(prio_to_weight
[prio
]);
750 load
->inv_weight
= prio_to_wmult
[prio
];
753 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
756 sched_info_queued(p
);
757 p
->sched_class
->enqueue_task(rq
, p
, flags
);
760 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
763 sched_info_dequeued(p
);
764 p
->sched_class
->dequeue_task(rq
, p
, flags
);
767 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
769 if (task_contributes_to_load(p
))
770 rq
->nr_uninterruptible
--;
772 enqueue_task(rq
, p
, flags
);
775 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
777 if (task_contributes_to_load(p
))
778 rq
->nr_uninterruptible
++;
780 dequeue_task(rq
, p
, flags
);
783 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
786 * In theory, the compile should just see 0 here, and optimize out the call
787 * to sched_rt_avg_update. But I don't trust it...
789 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
790 s64 steal
= 0, irq_delta
= 0;
792 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
793 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
796 * Since irq_time is only updated on {soft,}irq_exit, we might run into
797 * this case when a previous update_rq_clock() happened inside a
800 * When this happens, we stop ->clock_task and only update the
801 * prev_irq_time stamp to account for the part that fit, so that a next
802 * update will consume the rest. This ensures ->clock_task is
805 * It does however cause some slight miss-attribution of {soft,}irq
806 * time, a more accurate solution would be to update the irq_time using
807 * the current rq->clock timestamp, except that would require using
810 if (irq_delta
> delta
)
813 rq
->prev_irq_time
+= irq_delta
;
816 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
817 if (static_key_false((¶virt_steal_rq_enabled
))) {
820 steal
= paravirt_steal_clock(cpu_of(rq
));
821 steal
-= rq
->prev_steal_time_rq
;
823 if (unlikely(steal
> delta
))
826 st
= steal_ticks(steal
);
827 steal
= st
* TICK_NSEC
;
829 rq
->prev_steal_time_rq
+= steal
;
835 rq
->clock_task
+= delta
;
837 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
838 if ((irq_delta
+ steal
) && sched_feat(NONTASK_POWER
))
839 sched_rt_avg_update(rq
, irq_delta
+ steal
);
843 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
845 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
846 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
850 * Make it appear like a SCHED_FIFO task, its something
851 * userspace knows about and won't get confused about.
853 * Also, it will make PI more or less work without too
854 * much confusion -- but then, stop work should not
855 * rely on PI working anyway.
857 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
859 stop
->sched_class
= &stop_sched_class
;
862 cpu_rq(cpu
)->stop
= stop
;
866 * Reset it back to a normal scheduling class so that
867 * it can die in pieces.
869 old_stop
->sched_class
= &rt_sched_class
;
874 * __normal_prio - return the priority that is based on the static prio
876 static inline int __normal_prio(struct task_struct
*p
)
878 return p
->static_prio
;
882 * Calculate the expected normal priority: i.e. priority
883 * without taking RT-inheritance into account. Might be
884 * boosted by interactivity modifiers. Changes upon fork,
885 * setprio syscalls, and whenever the interactivity
886 * estimator recalculates.
888 static inline int normal_prio(struct task_struct
*p
)
892 if (task_has_rt_policy(p
))
893 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
895 prio
= __normal_prio(p
);
900 * Calculate the current priority, i.e. the priority
901 * taken into account by the scheduler. This value might
902 * be boosted by RT tasks, or might be boosted by
903 * interactivity modifiers. Will be RT if the task got
904 * RT-boosted. If not then it returns p->normal_prio.
906 static int effective_prio(struct task_struct
*p
)
908 p
->normal_prio
= normal_prio(p
);
910 * If we are RT tasks or we were boosted to RT priority,
911 * keep the priority unchanged. Otherwise, update priority
912 * to the normal priority:
914 if (!rt_prio(p
->prio
))
915 return p
->normal_prio
;
920 * task_curr - is this task currently executing on a CPU?
921 * @p: the task in question.
923 inline int task_curr(const struct task_struct
*p
)
925 return cpu_curr(task_cpu(p
)) == p
;
928 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
929 const struct sched_class
*prev_class
,
932 if (prev_class
!= p
->sched_class
) {
933 if (prev_class
->switched_from
)
934 prev_class
->switched_from(rq
, p
);
935 p
->sched_class
->switched_to(rq
, p
);
936 } else if (oldprio
!= p
->prio
)
937 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
940 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
942 const struct sched_class
*class;
944 if (p
->sched_class
== rq
->curr
->sched_class
) {
945 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
947 for_each_class(class) {
948 if (class == rq
->curr
->sched_class
)
950 if (class == p
->sched_class
) {
951 resched_task(rq
->curr
);
958 * A queue event has occurred, and we're going to schedule. In
959 * this case, we can save a useless back to back clock update.
961 if (rq
->curr
->on_rq
&& test_tsk_need_resched(rq
->curr
))
962 rq
->skip_clock_update
= 1;
965 static ATOMIC_NOTIFIER_HEAD(task_migration_notifier
);
967 void register_task_migration_notifier(struct notifier_block
*n
)
969 atomic_notifier_chain_register(&task_migration_notifier
, n
);
973 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
975 #ifdef CONFIG_SCHED_DEBUG
977 * We should never call set_task_cpu() on a blocked task,
978 * ttwu() will sort out the placement.
980 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
981 !(task_thread_info(p
)->preempt_count
& PREEMPT_ACTIVE
));
983 #ifdef CONFIG_LOCKDEP
985 * The caller should hold either p->pi_lock or rq->lock, when changing
986 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
988 * sched_move_task() holds both and thus holding either pins the cgroup,
991 * Furthermore, all task_rq users should acquire both locks, see
994 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
995 lockdep_is_held(&task_rq(p
)->lock
)));
999 trace_sched_migrate_task(p
, new_cpu
);
1001 if (task_cpu(p
) != new_cpu
) {
1002 struct task_migration_notifier tmn
;
1004 if (p
->sched_class
->migrate_task_rq
)
1005 p
->sched_class
->migrate_task_rq(p
, new_cpu
);
1006 p
->se
.nr_migrations
++;
1007 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, NULL
, 0);
1010 tmn
.from_cpu
= task_cpu(p
);
1011 tmn
.to_cpu
= new_cpu
;
1013 atomic_notifier_call_chain(&task_migration_notifier
, 0, &tmn
);
1016 __set_task_cpu(p
, new_cpu
);
1019 struct migration_arg
{
1020 struct task_struct
*task
;
1024 static int migration_cpu_stop(void *data
);
1027 * wait_task_inactive - wait for a thread to unschedule.
1029 * If @match_state is nonzero, it's the @p->state value just checked and
1030 * not expected to change. If it changes, i.e. @p might have woken up,
1031 * then return zero. When we succeed in waiting for @p to be off its CPU,
1032 * we return a positive number (its total switch count). If a second call
1033 * a short while later returns the same number, the caller can be sure that
1034 * @p has remained unscheduled the whole time.
1036 * The caller must ensure that the task *will* unschedule sometime soon,
1037 * else this function might spin for a *long* time. This function can't
1038 * be called with interrupts off, or it may introduce deadlock with
1039 * smp_call_function() if an IPI is sent by the same process we are
1040 * waiting to become inactive.
1042 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1044 unsigned long flags
;
1051 * We do the initial early heuristics without holding
1052 * any task-queue locks at all. We'll only try to get
1053 * the runqueue lock when things look like they will
1059 * If the task is actively running on another CPU
1060 * still, just relax and busy-wait without holding
1063 * NOTE! Since we don't hold any locks, it's not
1064 * even sure that "rq" stays as the right runqueue!
1065 * But we don't care, since "task_running()" will
1066 * return false if the runqueue has changed and p
1067 * is actually now running somewhere else!
1069 while (task_running(rq
, p
)) {
1070 if (match_state
&& unlikely(p
->state
!= match_state
))
1076 * Ok, time to look more closely! We need the rq
1077 * lock now, to be *sure*. If we're wrong, we'll
1078 * just go back and repeat.
1080 rq
= task_rq_lock(p
, &flags
);
1081 trace_sched_wait_task(p
);
1082 running
= task_running(rq
, p
);
1085 if (!match_state
|| p
->state
== match_state
)
1086 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1087 task_rq_unlock(rq
, p
, &flags
);
1090 * If it changed from the expected state, bail out now.
1092 if (unlikely(!ncsw
))
1096 * Was it really running after all now that we
1097 * checked with the proper locks actually held?
1099 * Oops. Go back and try again..
1101 if (unlikely(running
)) {
1107 * It's not enough that it's not actively running,
1108 * it must be off the runqueue _entirely_, and not
1111 * So if it was still runnable (but just not actively
1112 * running right now), it's preempted, and we should
1113 * yield - it could be a while.
1115 if (unlikely(on_rq
)) {
1116 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1118 set_current_state(TASK_UNINTERRUPTIBLE
);
1119 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1124 * Ahh, all good. It wasn't running, and it wasn't
1125 * runnable, which means that it will never become
1126 * running in the future either. We're all done!
1135 * kick_process - kick a running thread to enter/exit the kernel
1136 * @p: the to-be-kicked thread
1138 * Cause a process which is running on another CPU to enter
1139 * kernel-mode, without any delay. (to get signals handled.)
1141 * NOTE: this function doesn't have to take the runqueue lock,
1142 * because all it wants to ensure is that the remote task enters
1143 * the kernel. If the IPI races and the task has been migrated
1144 * to another CPU then no harm is done and the purpose has been
1147 void kick_process(struct task_struct
*p
)
1153 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1154 smp_send_reschedule(cpu
);
1157 EXPORT_SYMBOL_GPL(kick_process
);
1158 #endif /* CONFIG_SMP */
1162 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1164 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1166 int nid
= cpu_to_node(cpu
);
1167 const struct cpumask
*nodemask
= NULL
;
1168 enum { cpuset
, possible
, fail
} state
= cpuset
;
1172 * If the node that the cpu is on has been offlined, cpu_to_node()
1173 * will return -1. There is no cpu on the node, and we should
1174 * select the cpu on the other node.
1177 nodemask
= cpumask_of_node(nid
);
1179 /* Look for allowed, online CPU in same node. */
1180 for_each_cpu(dest_cpu
, nodemask
) {
1181 if (!cpu_online(dest_cpu
))
1183 if (!cpu_active(dest_cpu
))
1185 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1191 /* Any allowed, online CPU? */
1192 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1193 if (!cpu_online(dest_cpu
))
1195 if (!cpu_active(dest_cpu
))
1202 /* No more Mr. Nice Guy. */
1203 cpuset_cpus_allowed_fallback(p
);
1208 do_set_cpus_allowed(p
, cpu_possible_mask
);
1219 if (state
!= cpuset
) {
1221 * Don't tell them about moving exiting tasks or
1222 * kernel threads (both mm NULL), since they never
1225 if (p
->mm
&& printk_ratelimit()) {
1226 printk_sched("process %d (%s) no longer affine to cpu%d\n",
1227 task_pid_nr(p
), p
->comm
, cpu
);
1235 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1238 int select_task_rq(struct task_struct
*p
, int sd_flags
, int wake_flags
)
1240 int cpu
= p
->sched_class
->select_task_rq(p
, sd_flags
, wake_flags
);
1243 * In order not to call set_task_cpu() on a blocking task we need
1244 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1247 * Since this is common to all placement strategies, this lives here.
1249 * [ this allows ->select_task() to simply return task_cpu(p) and
1250 * not worry about this generic constraint ]
1252 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1254 cpu
= select_fallback_rq(task_cpu(p
), p
);
1259 static void update_avg(u64
*avg
, u64 sample
)
1261 s64 diff
= sample
- *avg
;
1267 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1269 #ifdef CONFIG_SCHEDSTATS
1270 struct rq
*rq
= this_rq();
1273 int this_cpu
= smp_processor_id();
1275 if (cpu
== this_cpu
) {
1276 schedstat_inc(rq
, ttwu_local
);
1277 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1279 struct sched_domain
*sd
;
1281 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1283 for_each_domain(this_cpu
, sd
) {
1284 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1285 schedstat_inc(sd
, ttwu_wake_remote
);
1292 if (wake_flags
& WF_MIGRATED
)
1293 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1295 #endif /* CONFIG_SMP */
1297 schedstat_inc(rq
, ttwu_count
);
1298 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1300 if (wake_flags
& WF_SYNC
)
1301 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1303 #endif /* CONFIG_SCHEDSTATS */
1306 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1308 activate_task(rq
, p
, en_flags
);
1311 /* if a worker is waking up, notify workqueue */
1312 if (p
->flags
& PF_WQ_WORKER
)
1313 wq_worker_waking_up(p
, cpu_of(rq
));
1317 * Mark the task runnable and perform wakeup-preemption.
1320 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1322 check_preempt_curr(rq
, p
, wake_flags
);
1323 trace_sched_wakeup(p
, true);
1325 p
->state
= TASK_RUNNING
;
1327 if (p
->sched_class
->task_woken
)
1328 p
->sched_class
->task_woken(rq
, p
);
1330 if (rq
->idle_stamp
) {
1331 u64 delta
= rq
->clock
- rq
->idle_stamp
;
1332 u64 max
= 2*sysctl_sched_migration_cost
;
1337 update_avg(&rq
->avg_idle
, delta
);
1344 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1347 if (p
->sched_contributes_to_load
)
1348 rq
->nr_uninterruptible
--;
1351 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1352 ttwu_do_wakeup(rq
, p
, wake_flags
);
1356 * Called in case the task @p isn't fully descheduled from its runqueue,
1357 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1358 * since all we need to do is flip p->state to TASK_RUNNING, since
1359 * the task is still ->on_rq.
1361 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1366 rq
= __task_rq_lock(p
);
1368 ttwu_do_wakeup(rq
, p
, wake_flags
);
1371 __task_rq_unlock(rq
);
1377 static void sched_ttwu_pending(void)
1379 struct rq
*rq
= this_rq();
1380 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1381 struct task_struct
*p
;
1383 raw_spin_lock(&rq
->lock
);
1386 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1387 llist
= llist_next(llist
);
1388 ttwu_do_activate(rq
, p
, 0);
1391 raw_spin_unlock(&rq
->lock
);
1394 void scheduler_ipi(void)
1396 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick()
1397 && !tick_nohz_full_cpu(smp_processor_id()))
1401 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1402 * traditionally all their work was done from the interrupt return
1403 * path. Now that we actually do some work, we need to make sure
1406 * Some archs already do call them, luckily irq_enter/exit nest
1409 * Arguably we should visit all archs and update all handlers,
1410 * however a fair share of IPIs are still resched only so this would
1411 * somewhat pessimize the simple resched case.
1414 tick_nohz_full_check();
1415 sched_ttwu_pending();
1418 * Check if someone kicked us for doing the nohz idle load balance.
1420 if (unlikely(got_nohz_idle_kick() && !need_resched())) {
1421 this_rq()->idle_balance
= 1;
1422 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1427 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1429 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
))
1430 smp_send_reschedule(cpu
);
1433 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1435 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1437 #endif /* CONFIG_SMP */
1439 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1441 struct rq
*rq
= cpu_rq(cpu
);
1443 #if defined(CONFIG_SMP)
1444 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1445 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1446 ttwu_queue_remote(p
, cpu
);
1451 raw_spin_lock(&rq
->lock
);
1452 ttwu_do_activate(rq
, p
, 0);
1453 raw_spin_unlock(&rq
->lock
);
1457 * try_to_wake_up - wake up a thread
1458 * @p: the thread to be awakened
1459 * @state: the mask of task states that can be woken
1460 * @wake_flags: wake modifier flags (WF_*)
1462 * Put it on the run-queue if it's not already there. The "current"
1463 * thread is always on the run-queue (except when the actual
1464 * re-schedule is in progress), and as such you're allowed to do
1465 * the simpler "current->state = TASK_RUNNING" to mark yourself
1466 * runnable without the overhead of this.
1468 * Returns %true if @p was woken up, %false if it was already running
1469 * or @state didn't match @p's state.
1472 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
1474 unsigned long flags
;
1475 int cpu
, success
= 0;
1478 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1479 if (!(p
->state
& state
))
1482 success
= 1; /* we're going to change ->state */
1485 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
1490 * If the owning (remote) cpu is still in the middle of schedule() with
1491 * this task as prev, wait until its done referencing the task.
1496 * Pairs with the smp_wmb() in finish_lock_switch().
1500 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
1501 p
->state
= TASK_WAKING
;
1503 if (p
->sched_class
->task_waking
)
1504 p
->sched_class
->task_waking(p
);
1506 cpu
= select_task_rq(p
, SD_BALANCE_WAKE
, wake_flags
);
1507 if (task_cpu(p
) != cpu
) {
1508 wake_flags
|= WF_MIGRATED
;
1509 set_task_cpu(p
, cpu
);
1511 #endif /* CONFIG_SMP */
1515 ttwu_stat(p
, cpu
, wake_flags
);
1517 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1523 * try_to_wake_up_local - try to wake up a local task with rq lock held
1524 * @p: the thread to be awakened
1526 * Put @p on the run-queue if it's not already there. The caller must
1527 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1530 static void try_to_wake_up_local(struct task_struct
*p
)
1532 struct rq
*rq
= task_rq(p
);
1534 if (WARN_ON_ONCE(rq
!= this_rq()) ||
1535 WARN_ON_ONCE(p
== current
))
1538 lockdep_assert_held(&rq
->lock
);
1540 if (!raw_spin_trylock(&p
->pi_lock
)) {
1541 raw_spin_unlock(&rq
->lock
);
1542 raw_spin_lock(&p
->pi_lock
);
1543 raw_spin_lock(&rq
->lock
);
1546 if (!(p
->state
& TASK_NORMAL
))
1550 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
1552 ttwu_do_wakeup(rq
, p
, 0);
1553 ttwu_stat(p
, smp_processor_id(), 0);
1555 raw_spin_unlock(&p
->pi_lock
);
1559 * wake_up_process - Wake up a specific process
1560 * @p: The process to be woken up.
1562 * Attempt to wake up the nominated process and move it to the set of runnable
1563 * processes. Returns 1 if the process was woken up, 0 if it was already
1566 * It may be assumed that this function implies a write memory barrier before
1567 * changing the task state if and only if any tasks are woken up.
1569 int wake_up_process(struct task_struct
*p
)
1571 WARN_ON(task_is_stopped_or_traced(p
));
1572 return try_to_wake_up(p
, TASK_NORMAL
, 0);
1574 EXPORT_SYMBOL(wake_up_process
);
1576 int wake_up_state(struct task_struct
*p
, unsigned int state
)
1578 return try_to_wake_up(p
, state
, 0);
1582 * Perform scheduler related setup for a newly forked process p.
1583 * p is forked by current.
1585 * __sched_fork() is basic setup used by init_idle() too:
1587 static void __sched_fork(struct task_struct
*p
)
1592 p
->se
.exec_start
= 0;
1593 p
->se
.sum_exec_runtime
= 0;
1594 p
->se
.prev_sum_exec_runtime
= 0;
1595 p
->se
.nr_migrations
= 0;
1597 INIT_LIST_HEAD(&p
->se
.group_node
);
1600 * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
1601 * removed when useful for applications beyond shares distribution (e.g.
1604 #if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
1605 p
->se
.avg
.runnable_avg_period
= 0;
1606 p
->se
.avg
.runnable_avg_sum
= 0;
1608 #ifdef CONFIG_SCHEDSTATS
1609 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
1612 INIT_LIST_HEAD(&p
->rt
.run_list
);
1614 #ifdef CONFIG_PREEMPT_NOTIFIERS
1615 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1618 #ifdef CONFIG_NUMA_BALANCING
1619 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
1620 p
->mm
->numa_next_scan
= jiffies
;
1621 p
->mm
->numa_next_reset
= jiffies
;
1622 p
->mm
->numa_scan_seq
= 0;
1625 p
->node_stamp
= 0ULL;
1626 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
1627 p
->numa_migrate_seq
= p
->mm
? p
->mm
->numa_scan_seq
- 1 : 0;
1628 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
1629 p
->numa_work
.next
= &p
->numa_work
;
1630 #endif /* CONFIG_NUMA_BALANCING */
1633 #ifdef CONFIG_NUMA_BALANCING
1634 #ifdef CONFIG_SCHED_DEBUG
1635 void set_numabalancing_state(bool enabled
)
1638 sched_feat_set("NUMA");
1640 sched_feat_set("NO_NUMA");
1643 __read_mostly
bool numabalancing_enabled
;
1645 void set_numabalancing_state(bool enabled
)
1647 numabalancing_enabled
= enabled
;
1649 #endif /* CONFIG_SCHED_DEBUG */
1650 #endif /* CONFIG_NUMA_BALANCING */
1653 * fork()/clone()-time setup:
1655 void sched_fork(struct task_struct
*p
)
1657 unsigned long flags
;
1658 int cpu
= get_cpu();
1662 * We mark the process as running here. This guarantees that
1663 * nobody will actually run it, and a signal or other external
1664 * event cannot wake it up and insert it on the runqueue either.
1666 p
->state
= TASK_RUNNING
;
1669 * Make sure we do not leak PI boosting priority to the child.
1671 p
->prio
= current
->normal_prio
;
1674 * Revert to default priority/policy on fork if requested.
1676 if (unlikely(p
->sched_reset_on_fork
)) {
1677 if (task_has_rt_policy(p
)) {
1678 p
->policy
= SCHED_NORMAL
;
1679 p
->static_prio
= NICE_TO_PRIO(0);
1681 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
1682 p
->static_prio
= NICE_TO_PRIO(0);
1684 p
->prio
= p
->normal_prio
= __normal_prio(p
);
1688 * We don't need the reset flag anymore after the fork. It has
1689 * fulfilled its duty:
1691 p
->sched_reset_on_fork
= 0;
1694 if (!rt_prio(p
->prio
))
1695 p
->sched_class
= &fair_sched_class
;
1697 if (p
->sched_class
->task_fork
)
1698 p
->sched_class
->task_fork(p
);
1701 * The child is not yet in the pid-hash so no cgroup attach races,
1702 * and the cgroup is pinned to this child due to cgroup_fork()
1703 * is ran before sched_fork().
1705 * Silence PROVE_RCU.
1707 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1708 set_task_cpu(p
, cpu
);
1709 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1711 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1712 if (likely(sched_info_on()))
1713 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1715 #if defined(CONFIG_SMP)
1718 #ifdef CONFIG_PREEMPT_COUNT
1719 /* Want to start with kernel preemption disabled. */
1720 task_thread_info(p
)->preempt_count
= 1;
1723 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
1730 * wake_up_new_task - wake up a newly created task for the first time.
1732 * This function will do some initial scheduler statistics housekeeping
1733 * that must be done for every newly created context, then puts the task
1734 * on the runqueue and wakes it.
1736 void wake_up_new_task(struct task_struct
*p
)
1738 unsigned long flags
;
1741 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1744 * Fork balancing, do it here and not earlier because:
1745 * - cpus_allowed can change in the fork path
1746 * - any previously selected cpu might disappear through hotplug
1748 set_task_cpu(p
, select_task_rq(p
, SD_BALANCE_FORK
, 0));
1751 rq
= __task_rq_lock(p
);
1752 activate_task(rq
, p
, 0);
1754 trace_sched_wakeup_new(p
, true);
1755 check_preempt_curr(rq
, p
, WF_FORK
);
1757 if (p
->sched_class
->task_woken
)
1758 p
->sched_class
->task_woken(rq
, p
);
1760 task_rq_unlock(rq
, p
, &flags
);
1763 #ifdef CONFIG_PREEMPT_NOTIFIERS
1766 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1767 * @notifier: notifier struct to register
1769 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1771 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1773 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1776 * preempt_notifier_unregister - no longer interested in preemption notifications
1777 * @notifier: notifier struct to unregister
1779 * This is safe to call from within a preemption notifier.
1781 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1783 hlist_del(¬ifier
->link
);
1785 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1787 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1789 struct preempt_notifier
*notifier
;
1791 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1792 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1796 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1797 struct task_struct
*next
)
1799 struct preempt_notifier
*notifier
;
1801 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
1802 notifier
->ops
->sched_out(notifier
, next
);
1805 #else /* !CONFIG_PREEMPT_NOTIFIERS */
1807 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1812 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1813 struct task_struct
*next
)
1817 #endif /* CONFIG_PREEMPT_NOTIFIERS */
1820 * prepare_task_switch - prepare to switch tasks
1821 * @rq: the runqueue preparing to switch
1822 * @prev: the current task that is being switched out
1823 * @next: the task we are going to switch to.
1825 * This is called with the rq lock held and interrupts off. It must
1826 * be paired with a subsequent finish_task_switch after the context
1829 * prepare_task_switch sets up locking and calls architecture specific
1833 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1834 struct task_struct
*next
)
1836 trace_sched_switch(prev
, next
);
1837 sched_info_switch(prev
, next
);
1838 perf_event_task_sched_out(prev
, next
);
1839 fire_sched_out_preempt_notifiers(prev
, next
);
1840 prepare_lock_switch(rq
, next
);
1841 prepare_arch_switch(next
);
1845 * finish_task_switch - clean up after a task-switch
1846 * @rq: runqueue associated with task-switch
1847 * @prev: the thread we just switched away from.
1849 * finish_task_switch must be called after the context switch, paired
1850 * with a prepare_task_switch call before the context switch.
1851 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1852 * and do any other architecture-specific cleanup actions.
1854 * Note that we may have delayed dropping an mm in context_switch(). If
1855 * so, we finish that here outside of the runqueue lock. (Doing it
1856 * with the lock held can cause deadlocks; see schedule() for
1859 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1860 __releases(rq
->lock
)
1862 struct mm_struct
*mm
= rq
->prev_mm
;
1868 * A task struct has one reference for the use as "current".
1869 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1870 * schedule one last time. The schedule call will never return, and
1871 * the scheduled task must drop that reference.
1872 * The test for TASK_DEAD must occur while the runqueue locks are
1873 * still held, otherwise prev could be scheduled on another cpu, die
1874 * there before we look at prev->state, and then the reference would
1876 * Manfred Spraul <manfred@colorfullife.com>
1878 prev_state
= prev
->state
;
1879 vtime_task_switch(prev
);
1880 finish_arch_switch(prev
);
1881 perf_event_task_sched_in(prev
, current
);
1882 finish_lock_switch(rq
, prev
);
1883 finish_arch_post_lock_switch();
1885 fire_sched_in_preempt_notifiers(current
);
1888 if (unlikely(prev_state
== TASK_DEAD
)) {
1890 * Remove function-return probe instances associated with this
1891 * task and put them back on the free list.
1893 kprobe_flush_task(prev
);
1894 put_task_struct(prev
);
1897 tick_nohz_task_switch(current
);
1902 /* assumes rq->lock is held */
1903 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*prev
)
1905 if (prev
->sched_class
->pre_schedule
)
1906 prev
->sched_class
->pre_schedule(rq
, prev
);
1909 /* rq->lock is NOT held, but preemption is disabled */
1910 static inline void post_schedule(struct rq
*rq
)
1912 if (rq
->post_schedule
) {
1913 unsigned long flags
;
1915 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1916 if (rq
->curr
->sched_class
->post_schedule
)
1917 rq
->curr
->sched_class
->post_schedule(rq
);
1918 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1920 rq
->post_schedule
= 0;
1926 static inline void pre_schedule(struct rq
*rq
, struct task_struct
*p
)
1930 static inline void post_schedule(struct rq
*rq
)
1937 * schedule_tail - first thing a freshly forked thread must call.
1938 * @prev: the thread we just switched away from.
1940 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1941 __releases(rq
->lock
)
1943 struct rq
*rq
= this_rq();
1945 finish_task_switch(rq
, prev
);
1948 * FIXME: do we need to worry about rq being invalidated by the
1953 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1954 /* In this case, finish_task_switch does not reenable preemption */
1957 if (current
->set_child_tid
)
1958 put_user(task_pid_vnr(current
), current
->set_child_tid
);
1962 * context_switch - switch to the new MM and the new
1963 * thread's register state.
1966 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1967 struct task_struct
*next
)
1969 struct mm_struct
*mm
, *oldmm
;
1971 prepare_task_switch(rq
, prev
, next
);
1974 oldmm
= prev
->active_mm
;
1976 * For paravirt, this is coupled with an exit in switch_to to
1977 * combine the page table reload and the switch backend into
1980 arch_start_context_switch(prev
);
1983 next
->active_mm
= oldmm
;
1984 atomic_inc(&oldmm
->mm_count
);
1985 enter_lazy_tlb(oldmm
, next
);
1987 switch_mm(oldmm
, mm
, next
);
1990 prev
->active_mm
= NULL
;
1991 rq
->prev_mm
= oldmm
;
1994 * Since the runqueue lock will be released by the next
1995 * task (which is an invalid locking op but in the case
1996 * of the scheduler it's an obvious special-case), so we
1997 * do an early lockdep release here:
1999 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2000 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2003 context_tracking_task_switch(prev
, next
);
2004 /* Here we just switch the register state and the stack. */
2005 switch_to(prev
, next
, prev
);
2009 * this_rq must be evaluated again because prev may have moved
2010 * CPUs since it called schedule(), thus the 'rq' on its stack
2011 * frame will be invalid.
2013 finish_task_switch(this_rq(), prev
);
2017 * nr_running and nr_context_switches:
2019 * externally visible scheduler statistics: current number of runnable
2020 * threads, total number of context switches performed since bootup.
2022 unsigned long nr_running(void)
2024 unsigned long i
, sum
= 0;
2026 for_each_online_cpu(i
)
2027 sum
+= cpu_rq(i
)->nr_running
;
2032 unsigned long long nr_context_switches(void)
2035 unsigned long long sum
= 0;
2037 for_each_possible_cpu(i
)
2038 sum
+= cpu_rq(i
)->nr_switches
;
2043 unsigned long nr_iowait(void)
2045 unsigned long i
, sum
= 0;
2047 for_each_possible_cpu(i
)
2048 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2053 unsigned long nr_iowait_cpu(int cpu
)
2055 struct rq
*this = cpu_rq(cpu
);
2056 return atomic_read(&this->nr_iowait
);
2059 unsigned long this_cpu_load(void)
2061 struct rq
*this = this_rq();
2062 return this->cpu_load
[0];
2067 * Global load-average calculations
2069 * We take a distributed and async approach to calculating the global load-avg
2070 * in order to minimize overhead.
2072 * The global load average is an exponentially decaying average of nr_running +
2073 * nr_uninterruptible.
2075 * Once every LOAD_FREQ:
2078 * for_each_possible_cpu(cpu)
2079 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible;
2081 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n)
2083 * Due to a number of reasons the above turns in the mess below:
2085 * - for_each_possible_cpu() is prohibitively expensive on machines with
2086 * serious number of cpus, therefore we need to take a distributed approach
2087 * to calculating nr_active.
2089 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0
2090 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) }
2092 * So assuming nr_active := 0 when we start out -- true per definition, we
2093 * can simply take per-cpu deltas and fold those into a global accumulate
2094 * to obtain the same result. See calc_load_fold_active().
2096 * Furthermore, in order to avoid synchronizing all per-cpu delta folding
2097 * across the machine, we assume 10 ticks is sufficient time for every
2098 * cpu to have completed this task.
2100 * This places an upper-bound on the IRQ-off latency of the machine. Then
2101 * again, being late doesn't loose the delta, just wrecks the sample.
2103 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because
2104 * this would add another cross-cpu cacheline miss and atomic operation
2105 * to the wakeup path. Instead we increment on whatever cpu the task ran
2106 * when it went into uninterruptible state and decrement on whatever cpu
2107 * did the wakeup. This means that only the sum of nr_uninterruptible over
2108 * all cpus yields the correct result.
2110 * This covers the NO_HZ=n code, for extra head-aches, see the comment below.
2113 /* Variables and functions for calc_load */
2114 static atomic_long_t calc_load_tasks
;
2115 static unsigned long calc_load_update
;
2116 unsigned long avenrun
[3];
2117 EXPORT_SYMBOL(avenrun
); /* should be removed */
2120 * get_avenrun - get the load average array
2121 * @loads: pointer to dest load array
2122 * @offset: offset to add
2123 * @shift: shift count to shift the result left
2125 * These values are estimates at best, so no need for locking.
2127 void get_avenrun(unsigned long *loads
, unsigned long offset
, int shift
)
2129 loads
[0] = (avenrun
[0] + offset
) << shift
;
2130 loads
[1] = (avenrun
[1] + offset
) << shift
;
2131 loads
[2] = (avenrun
[2] + offset
) << shift
;
2134 static long calc_load_fold_active(struct rq
*this_rq
)
2136 long nr_active
, delta
= 0;
2138 nr_active
= this_rq
->nr_running
;
2139 nr_active
+= (long) this_rq
->nr_uninterruptible
;
2141 if (nr_active
!= this_rq
->calc_load_active
) {
2142 delta
= nr_active
- this_rq
->calc_load_active
;
2143 this_rq
->calc_load_active
= nr_active
;
2150 * a1 = a0 * e + a * (1 - e)
2152 static unsigned long
2153 calc_load(unsigned long load
, unsigned long exp
, unsigned long active
)
2156 load
+= active
* (FIXED_1
- exp
);
2157 load
+= 1UL << (FSHIFT
- 1);
2158 return load
>> FSHIFT
;
2161 #ifdef CONFIG_NO_HZ_COMMON
2163 * Handle NO_HZ for the global load-average.
2165 * Since the above described distributed algorithm to compute the global
2166 * load-average relies on per-cpu sampling from the tick, it is affected by
2169 * The basic idea is to fold the nr_active delta into a global idle-delta upon
2170 * entering NO_HZ state such that we can include this as an 'extra' cpu delta
2171 * when we read the global state.
2173 * Obviously reality has to ruin such a delightfully simple scheme:
2175 * - When we go NO_HZ idle during the window, we can negate our sample
2176 * contribution, causing under-accounting.
2178 * We avoid this by keeping two idle-delta counters and flipping them
2179 * when the window starts, thus separating old and new NO_HZ load.
2181 * The only trick is the slight shift in index flip for read vs write.
2185 * |-|-----------|-|-----------|-|-----------|-|
2186 * r:0 0 1 1 0 0 1 1 0
2187 * w:0 1 1 0 0 1 1 0 0
2189 * This ensures we'll fold the old idle contribution in this window while
2190 * accumlating the new one.
2192 * - When we wake up from NO_HZ idle during the window, we push up our
2193 * contribution, since we effectively move our sample point to a known
2196 * This is solved by pushing the window forward, and thus skipping the
2197 * sample, for this cpu (effectively using the idle-delta for this cpu which
2198 * was in effect at the time the window opened). This also solves the issue
2199 * of having to deal with a cpu having been in NOHZ idle for multiple
2200 * LOAD_FREQ intervals.
2202 * When making the ILB scale, we should try to pull this in as well.
2204 static atomic_long_t calc_load_idle
[2];
2205 static int calc_load_idx
;
2207 static inline int calc_load_write_idx(void)
2209 int idx
= calc_load_idx
;
2212 * See calc_global_nohz(), if we observe the new index, we also
2213 * need to observe the new update time.
2218 * If the folding window started, make sure we start writing in the
2221 if (!time_before(jiffies
, calc_load_update
))
2227 static inline int calc_load_read_idx(void)
2229 return calc_load_idx
& 1;
2232 void calc_load_enter_idle(void)
2234 struct rq
*this_rq
= this_rq();
2238 * We're going into NOHZ mode, if there's any pending delta, fold it
2239 * into the pending idle delta.
2241 delta
= calc_load_fold_active(this_rq
);
2243 int idx
= calc_load_write_idx();
2244 atomic_long_add(delta
, &calc_load_idle
[idx
]);
2248 void calc_load_exit_idle(void)
2250 struct rq
*this_rq
= this_rq();
2253 * If we're still before the sample window, we're done.
2255 if (time_before(jiffies
, this_rq
->calc_load_update
))
2259 * We woke inside or after the sample window, this means we're already
2260 * accounted through the nohz accounting, so skip the entire deal and
2261 * sync up for the next window.
2263 this_rq
->calc_load_update
= calc_load_update
;
2264 if (time_before(jiffies
, this_rq
->calc_load_update
+ 10))
2265 this_rq
->calc_load_update
+= LOAD_FREQ
;
2268 static long calc_load_fold_idle(void)
2270 int idx
= calc_load_read_idx();
2273 if (atomic_long_read(&calc_load_idle
[idx
]))
2274 delta
= atomic_long_xchg(&calc_load_idle
[idx
], 0);
2280 * fixed_power_int - compute: x^n, in O(log n) time
2282 * @x: base of the power
2283 * @frac_bits: fractional bits of @x
2284 * @n: power to raise @x to.
2286 * By exploiting the relation between the definition of the natural power
2287 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
2288 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
2289 * (where: n_i \elem {0, 1}, the binary vector representing n),
2290 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
2291 * of course trivially computable in O(log_2 n), the length of our binary
2294 static unsigned long
2295 fixed_power_int(unsigned long x
, unsigned int frac_bits
, unsigned int n
)
2297 unsigned long result
= 1UL << frac_bits
;
2302 result
+= 1UL << (frac_bits
- 1);
2303 result
>>= frac_bits
;
2309 x
+= 1UL << (frac_bits
- 1);
2317 * a1 = a0 * e + a * (1 - e)
2319 * a2 = a1 * e + a * (1 - e)
2320 * = (a0 * e + a * (1 - e)) * e + a * (1 - e)
2321 * = a0 * e^2 + a * (1 - e) * (1 + e)
2323 * a3 = a2 * e + a * (1 - e)
2324 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
2325 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
2329 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
2330 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
2331 * = a0 * e^n + a * (1 - e^n)
2333 * [1] application of the geometric series:
2336 * S_n := \Sum x^i = -------------
2339 static unsigned long
2340 calc_load_n(unsigned long load
, unsigned long exp
,
2341 unsigned long active
, unsigned int n
)
2344 return calc_load(load
, fixed_power_int(exp
, FSHIFT
, n
), active
);
2348 * NO_HZ can leave us missing all per-cpu ticks calling
2349 * calc_load_account_active(), but since an idle CPU folds its delta into
2350 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
2351 * in the pending idle delta if our idle period crossed a load cycle boundary.
2353 * Once we've updated the global active value, we need to apply the exponential
2354 * weights adjusted to the number of cycles missed.
2356 static void calc_global_nohz(void)
2358 long delta
, active
, n
;
2360 if (!time_before(jiffies
, calc_load_update
+ 10)) {
2362 * Catch-up, fold however many we are behind still
2364 delta
= jiffies
- calc_load_update
- 10;
2365 n
= 1 + (delta
/ LOAD_FREQ
);
2367 active
= atomic_long_read(&calc_load_tasks
);
2368 active
= active
> 0 ? active
* FIXED_1
: 0;
2370 avenrun
[0] = calc_load_n(avenrun
[0], EXP_1
, active
, n
);
2371 avenrun
[1] = calc_load_n(avenrun
[1], EXP_5
, active
, n
);
2372 avenrun
[2] = calc_load_n(avenrun
[2], EXP_15
, active
, n
);
2374 calc_load_update
+= n
* LOAD_FREQ
;
2378 * Flip the idle index...
2380 * Make sure we first write the new time then flip the index, so that
2381 * calc_load_write_idx() will see the new time when it reads the new
2382 * index, this avoids a double flip messing things up.
2387 #else /* !CONFIG_NO_HZ_COMMON */
2389 static inline long calc_load_fold_idle(void) { return 0; }
2390 static inline void calc_global_nohz(void) { }
2392 #endif /* CONFIG_NO_HZ_COMMON */
2395 * calc_load - update the avenrun load estimates 10 ticks after the
2396 * CPUs have updated calc_load_tasks.
2398 void calc_global_load(unsigned long ticks
)
2402 if (time_before(jiffies
, calc_load_update
+ 10))
2406 * Fold the 'old' idle-delta to include all NO_HZ cpus.
2408 delta
= calc_load_fold_idle();
2410 atomic_long_add(delta
, &calc_load_tasks
);
2412 active
= atomic_long_read(&calc_load_tasks
);
2413 active
= active
> 0 ? active
* FIXED_1
: 0;
2415 avenrun
[0] = calc_load(avenrun
[0], EXP_1
, active
);
2416 avenrun
[1] = calc_load(avenrun
[1], EXP_5
, active
);
2417 avenrun
[2] = calc_load(avenrun
[2], EXP_15
, active
);
2419 calc_load_update
+= LOAD_FREQ
;
2422 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk.
2428 * Called from update_cpu_load() to periodically update this CPU's
2431 static void calc_load_account_active(struct rq
*this_rq
)
2435 if (time_before(jiffies
, this_rq
->calc_load_update
))
2438 delta
= calc_load_fold_active(this_rq
);
2440 atomic_long_add(delta
, &calc_load_tasks
);
2442 this_rq
->calc_load_update
+= LOAD_FREQ
;
2446 * End of global load-average stuff
2450 * The exact cpuload at various idx values, calculated at every tick would be
2451 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
2453 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
2454 * on nth tick when cpu may be busy, then we have:
2455 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2456 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
2458 * decay_load_missed() below does efficient calculation of
2459 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2460 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
2462 * The calculation is approximated on a 128 point scale.
2463 * degrade_zero_ticks is the number of ticks after which load at any
2464 * particular idx is approximated to be zero.
2465 * degrade_factor is a precomputed table, a row for each load idx.
2466 * Each column corresponds to degradation factor for a power of two ticks,
2467 * based on 128 point scale.
2469 * row 2, col 3 (=12) says that the degradation at load idx 2 after
2470 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
2472 * With this power of 2 load factors, we can degrade the load n times
2473 * by looking at 1 bits in n and doing as many mult/shift instead of
2474 * n mult/shifts needed by the exact degradation.
2476 #define DEGRADE_SHIFT 7
2477 static const unsigned char
2478 degrade_zero_ticks
[CPU_LOAD_IDX_MAX
] = {0, 8, 32, 64, 128};
2479 static const unsigned char
2480 degrade_factor
[CPU_LOAD_IDX_MAX
][DEGRADE_SHIFT
+ 1] = {
2481 {0, 0, 0, 0, 0, 0, 0, 0},
2482 {64, 32, 8, 0, 0, 0, 0, 0},
2483 {96, 72, 40, 12, 1, 0, 0},
2484 {112, 98, 75, 43, 15, 1, 0},
2485 {120, 112, 98, 76, 45, 16, 2} };
2488 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
2489 * would be when CPU is idle and so we just decay the old load without
2490 * adding any new load.
2492 static unsigned long
2493 decay_load_missed(unsigned long load
, unsigned long missed_updates
, int idx
)
2497 if (!missed_updates
)
2500 if (missed_updates
>= degrade_zero_ticks
[idx
])
2504 return load
>> missed_updates
;
2506 while (missed_updates
) {
2507 if (missed_updates
% 2)
2508 load
= (load
* degrade_factor
[idx
][j
]) >> DEGRADE_SHIFT
;
2510 missed_updates
>>= 1;
2517 * Update rq->cpu_load[] statistics. This function is usually called every
2518 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
2519 * every tick. We fix it up based on jiffies.
2521 static void __update_cpu_load(struct rq
*this_rq
, unsigned long this_load
,
2522 unsigned long pending_updates
)
2526 this_rq
->nr_load_updates
++;
2528 /* Update our load: */
2529 this_rq
->cpu_load
[0] = this_load
; /* Fasttrack for idx 0 */
2530 for (i
= 1, scale
= 2; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2531 unsigned long old_load
, new_load
;
2533 /* scale is effectively 1 << i now, and >> i divides by scale */
2535 old_load
= this_rq
->cpu_load
[i
];
2536 old_load
= decay_load_missed(old_load
, pending_updates
- 1, i
);
2537 new_load
= this_load
;
2539 * Round up the averaging division if load is increasing. This
2540 * prevents us from getting stuck on 9 if the load is 10, for
2543 if (new_load
> old_load
)
2544 new_load
+= scale
- 1;
2546 this_rq
->cpu_load
[i
] = (old_load
* (scale
- 1) + new_load
) >> i
;
2549 sched_avg_update(this_rq
);
2552 #ifdef CONFIG_NO_HZ_COMMON
2554 * There is no sane way to deal with nohz on smp when using jiffies because the
2555 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
2556 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
2558 * Therefore we cannot use the delta approach from the regular tick since that
2559 * would seriously skew the load calculation. However we'll make do for those
2560 * updates happening while idle (nohz_idle_balance) or coming out of idle
2561 * (tick_nohz_idle_exit).
2563 * This means we might still be one tick off for nohz periods.
2567 * Called from nohz_idle_balance() to update the load ratings before doing the
2570 void update_idle_cpu_load(struct rq
*this_rq
)
2572 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2573 unsigned long load
= this_rq
->load
.weight
;
2574 unsigned long pending_updates
;
2577 * bail if there's load or we're actually up-to-date.
2579 if (load
|| curr_jiffies
== this_rq
->last_load_update_tick
)
2582 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2583 this_rq
->last_load_update_tick
= curr_jiffies
;
2585 __update_cpu_load(this_rq
, load
, pending_updates
);
2589 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
2591 void update_cpu_load_nohz(void)
2593 struct rq
*this_rq
= this_rq();
2594 unsigned long curr_jiffies
= ACCESS_ONCE(jiffies
);
2595 unsigned long pending_updates
;
2597 if (curr_jiffies
== this_rq
->last_load_update_tick
)
2600 raw_spin_lock(&this_rq
->lock
);
2601 pending_updates
= curr_jiffies
- this_rq
->last_load_update_tick
;
2602 if (pending_updates
) {
2603 this_rq
->last_load_update_tick
= curr_jiffies
;
2605 * We were idle, this means load 0, the current load might be
2606 * !0 due to remote wakeups and the sort.
2608 __update_cpu_load(this_rq
, 0, pending_updates
);
2610 raw_spin_unlock(&this_rq
->lock
);
2612 #endif /* CONFIG_NO_HZ_COMMON */
2615 * Called from scheduler_tick()
2617 static void update_cpu_load_active(struct rq
*this_rq
)
2620 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
2622 this_rq
->last_load_update_tick
= jiffies
;
2623 __update_cpu_load(this_rq
, this_rq
->load
.weight
, 1);
2625 calc_load_account_active(this_rq
);
2631 * sched_exec - execve() is a valuable balancing opportunity, because at
2632 * this point the task has the smallest effective memory and cache footprint.
2634 void sched_exec(void)
2636 struct task_struct
*p
= current
;
2637 unsigned long flags
;
2640 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2641 dest_cpu
= p
->sched_class
->select_task_rq(p
, SD_BALANCE_EXEC
, 0);
2642 if (dest_cpu
== smp_processor_id())
2645 if (likely(cpu_active(dest_cpu
))) {
2646 struct migration_arg arg
= { p
, dest_cpu
};
2648 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2649 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2653 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2658 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2659 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2661 EXPORT_PER_CPU_SYMBOL(kstat
);
2662 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2665 * Return any ns on the sched_clock that have not yet been accounted in
2666 * @p in case that task is currently running.
2668 * Called with task_rq_lock() held on @rq.
2670 static u64
do_task_delta_exec(struct task_struct
*p
, struct rq
*rq
)
2674 if (task_current(rq
, p
)) {
2675 update_rq_clock(rq
);
2676 ns
= rq
->clock_task
- p
->se
.exec_start
;
2684 unsigned long long task_delta_exec(struct task_struct
*p
)
2686 unsigned long flags
;
2690 rq
= task_rq_lock(p
, &flags
);
2691 ns
= do_task_delta_exec(p
, rq
);
2692 task_rq_unlock(rq
, p
, &flags
);
2698 * Return accounted runtime for the task.
2699 * In case the task is currently running, return the runtime plus current's
2700 * pending runtime that have not been accounted yet.
2702 unsigned long long task_sched_runtime(struct task_struct
*p
)
2704 unsigned long flags
;
2708 rq
= task_rq_lock(p
, &flags
);
2709 ns
= p
->se
.sum_exec_runtime
+ do_task_delta_exec(p
, rq
);
2710 task_rq_unlock(rq
, p
, &flags
);
2716 * This function gets called by the timer code, with HZ frequency.
2717 * We call it with interrupts disabled.
2719 void scheduler_tick(void)
2721 int cpu
= smp_processor_id();
2722 struct rq
*rq
= cpu_rq(cpu
);
2723 struct task_struct
*curr
= rq
->curr
;
2727 raw_spin_lock(&rq
->lock
);
2728 update_rq_clock(rq
);
2729 update_cpu_load_active(rq
);
2730 curr
->sched_class
->task_tick(rq
, curr
, 0);
2731 raw_spin_unlock(&rq
->lock
);
2733 perf_event_task_tick();
2736 rq
->idle_balance
= idle_cpu(cpu
);
2737 trigger_load_balance(rq
, cpu
);
2739 rq_last_tick_reset(rq
);
2742 #ifdef CONFIG_NO_HZ_FULL
2744 * scheduler_tick_max_deferment
2746 * Keep at least one tick per second when a single
2747 * active task is running because the scheduler doesn't
2748 * yet completely support full dynticks environment.
2750 * This makes sure that uptime, CFS vruntime, load
2751 * balancing, etc... continue to move forward, even
2752 * with a very low granularity.
2754 u64
scheduler_tick_max_deferment(void)
2756 struct rq
*rq
= this_rq();
2757 unsigned long next
, now
= ACCESS_ONCE(jiffies
);
2759 next
= rq
->last_sched_tick
+ HZ
;
2761 if (time_before_eq(next
, now
))
2764 return jiffies_to_usecs(next
- now
) * NSEC_PER_USEC
;
2768 notrace
unsigned long get_parent_ip(unsigned long addr
)
2770 if (in_lock_functions(addr
)) {
2771 addr
= CALLER_ADDR2
;
2772 if (in_lock_functions(addr
))
2773 addr
= CALLER_ADDR3
;
2778 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2779 defined(CONFIG_PREEMPT_TRACER))
2781 void __kprobes
add_preempt_count(int val
)
2783 #ifdef CONFIG_DEBUG_PREEMPT
2787 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2790 preempt_count() += val
;
2791 #ifdef CONFIG_DEBUG_PREEMPT
2793 * Spinlock count overflowing soon?
2795 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
2798 if (preempt_count() == val
)
2799 trace_preempt_off(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2801 EXPORT_SYMBOL(add_preempt_count
);
2803 void __kprobes
sub_preempt_count(int val
)
2805 #ifdef CONFIG_DEBUG_PREEMPT
2809 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
2812 * Is the spinlock portion underflowing?
2814 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
2815 !(preempt_count() & PREEMPT_MASK
)))
2819 if (preempt_count() == val
)
2820 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2821 preempt_count() -= val
;
2823 EXPORT_SYMBOL(sub_preempt_count
);
2828 * Print scheduling while atomic bug:
2830 static noinline
void __schedule_bug(struct task_struct
*prev
)
2832 if (oops_in_progress
)
2835 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
2836 prev
->comm
, prev
->pid
, preempt_count());
2838 debug_show_held_locks(prev
);
2840 if (irqs_disabled())
2841 print_irqtrace_events(prev
);
2843 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
2847 * Various schedule()-time debugging checks and statistics:
2849 static inline void schedule_debug(struct task_struct
*prev
)
2852 * Test if we are atomic. Since do_exit() needs to call into
2853 * schedule() atomically, we ignore that path for now.
2854 * Otherwise, whine if we are scheduling when we should not be.
2856 if (unlikely(in_atomic_preempt_off() && !prev
->exit_state
))
2857 __schedule_bug(prev
);
2860 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2862 schedstat_inc(this_rq(), sched_count
);
2865 static void put_prev_task(struct rq
*rq
, struct task_struct
*prev
)
2867 if (prev
->on_rq
|| rq
->skip_clock_update
< 0)
2868 update_rq_clock(rq
);
2869 prev
->sched_class
->put_prev_task(rq
, prev
);
2873 * Pick up the highest-prio task:
2875 static inline struct task_struct
*
2876 pick_next_task(struct rq
*rq
)
2878 const struct sched_class
*class;
2879 struct task_struct
*p
;
2882 * Optimization: we know that if all tasks are in
2883 * the fair class we can call that function directly:
2885 if (likely(rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
2886 p
= fair_sched_class
.pick_next_task(rq
);
2891 for_each_class(class) {
2892 p
= class->pick_next_task(rq
);
2897 BUG(); /* the idle class will always have a runnable task */
2901 * __schedule() is the main scheduler function.
2903 * The main means of driving the scheduler and thus entering this function are:
2905 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2907 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2908 * paths. For example, see arch/x86/entry_64.S.
2910 * To drive preemption between tasks, the scheduler sets the flag in timer
2911 * interrupt handler scheduler_tick().
2913 * 3. Wakeups don't really cause entry into schedule(). They add a
2914 * task to the run-queue and that's it.
2916 * Now, if the new task added to the run-queue preempts the current
2917 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2918 * called on the nearest possible occasion:
2920 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2922 * - in syscall or exception context, at the next outmost
2923 * preempt_enable(). (this might be as soon as the wake_up()'s
2926 * - in IRQ context, return from interrupt-handler to
2927 * preemptible context
2929 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2932 * - cond_resched() call
2933 * - explicit schedule() call
2934 * - return from syscall or exception to user-space
2935 * - return from interrupt-handler to user-space
2937 static void __sched
__schedule(void)
2939 struct task_struct
*prev
, *next
;
2940 unsigned long *switch_count
;
2946 cpu
= smp_processor_id();
2948 rcu_note_context_switch(cpu
);
2951 schedule_debug(prev
);
2953 if (sched_feat(HRTICK
))
2956 raw_spin_lock_irq(&rq
->lock
);
2958 switch_count
= &prev
->nivcsw
;
2959 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2960 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
2961 prev
->state
= TASK_RUNNING
;
2963 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
2967 * If a worker went to sleep, notify and ask workqueue
2968 * whether it wants to wake up a task to maintain
2971 if (prev
->flags
& PF_WQ_WORKER
) {
2972 struct task_struct
*to_wakeup
;
2974 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
2976 try_to_wake_up_local(to_wakeup
);
2979 switch_count
= &prev
->nvcsw
;
2982 pre_schedule(rq
, prev
);
2984 if (unlikely(!rq
->nr_running
))
2985 idle_balance(cpu
, rq
);
2987 put_prev_task(rq
, prev
);
2988 next
= pick_next_task(rq
);
2989 clear_tsk_need_resched(prev
);
2990 rq
->skip_clock_update
= 0;
2992 if (likely(prev
!= next
)) {
2997 context_switch(rq
, prev
, next
); /* unlocks the rq */
2999 * The context switch have flipped the stack from under us
3000 * and restored the local variables which were saved when
3001 * this task called schedule() in the past. prev == current
3002 * is still correct, but it can be moved to another cpu/rq.
3004 cpu
= smp_processor_id();
3007 raw_spin_unlock_irq(&rq
->lock
);
3011 sched_preempt_enable_no_resched();
3016 static inline void sched_submit_work(struct task_struct
*tsk
)
3018 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
3021 * If we are going to sleep and we have plugged IO queued,
3022 * make sure to submit it to avoid deadlocks.
3024 if (blk_needs_flush_plug(tsk
))
3025 blk_schedule_flush_plug(tsk
);
3028 asmlinkage
void __sched
schedule(void)
3030 struct task_struct
*tsk
= current
;
3032 sched_submit_work(tsk
);
3035 EXPORT_SYMBOL(schedule
);
3037 #ifdef CONFIG_CONTEXT_TRACKING
3038 asmlinkage
void __sched
schedule_user(void)
3041 * If we come here after a random call to set_need_resched(),
3042 * or we have been woken up remotely but the IPI has not yet arrived,
3043 * we haven't yet exited the RCU idle mode. Do it here manually until
3044 * we find a better solution.
3053 * schedule_preempt_disabled - called with preemption disabled
3055 * Returns with preemption disabled. Note: preempt_count must be 1
3057 void __sched
schedule_preempt_disabled(void)
3059 sched_preempt_enable_no_resched();
3064 #ifdef CONFIG_PREEMPT
3066 * this is the entry point to schedule() from in-kernel preemption
3067 * off of preempt_enable. Kernel preemptions off return from interrupt
3068 * occur there and call schedule directly.
3070 asmlinkage
void __sched notrace
preempt_schedule(void)
3072 struct thread_info
*ti
= current_thread_info();
3075 * If there is a non-zero preempt_count or interrupts are disabled,
3076 * we do not want to preempt the current task. Just return..
3078 if (likely(ti
->preempt_count
|| irqs_disabled()))
3082 add_preempt_count_notrace(PREEMPT_ACTIVE
);
3084 sub_preempt_count_notrace(PREEMPT_ACTIVE
);
3087 * Check again in case we missed a preemption opportunity
3088 * between schedule and now.
3091 } while (need_resched());
3093 EXPORT_SYMBOL(preempt_schedule
);
3096 * this is the entry point to schedule() from kernel preemption
3097 * off of irq context.
3098 * Note, that this is called and return with irqs disabled. This will
3099 * protect us against recursive calling from irq.
3101 asmlinkage
void __sched
preempt_schedule_irq(void)
3103 struct thread_info
*ti
= current_thread_info();
3104 enum ctx_state prev_state
;
3106 /* Catch callers which need to be fixed */
3107 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3109 prev_state
= exception_enter();
3112 add_preempt_count(PREEMPT_ACTIVE
);
3115 local_irq_disable();
3116 sub_preempt_count(PREEMPT_ACTIVE
);
3119 * Check again in case we missed a preemption opportunity
3120 * between schedule and now.
3123 } while (need_resched());
3125 exception_exit(prev_state
);
3128 #endif /* CONFIG_PREEMPT */
3130 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
3133 return try_to_wake_up(curr
->private, mode
, wake_flags
);
3135 EXPORT_SYMBOL(default_wake_function
);
3138 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3139 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3140 * number) then we wake all the non-exclusive tasks and one exclusive task.
3142 * There are circumstances in which we can try to wake a task which has already
3143 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3144 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3146 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3147 int nr_exclusive
, int wake_flags
, void *key
)
3149 wait_queue_t
*curr
, *next
;
3151 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3152 unsigned flags
= curr
->flags
;
3154 if (curr
->func(curr
, mode
, wake_flags
, key
) &&
3155 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3161 * __wake_up - wake up threads blocked on a waitqueue.
3163 * @mode: which threads
3164 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3165 * @key: is directly passed to the wakeup function
3167 * It may be assumed that this function implies a write memory barrier before
3168 * changing the task state if and only if any tasks are woken up.
3170 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3171 int nr_exclusive
, void *key
)
3173 unsigned long flags
;
3175 spin_lock_irqsave(&q
->lock
, flags
);
3176 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3177 spin_unlock_irqrestore(&q
->lock
, flags
);
3179 EXPORT_SYMBOL(__wake_up
);
3182 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3184 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
, int nr
)
3186 __wake_up_common(q
, mode
, nr
, 0, NULL
);
3188 EXPORT_SYMBOL_GPL(__wake_up_locked
);
3190 void __wake_up_locked_key(wait_queue_head_t
*q
, unsigned int mode
, void *key
)
3192 __wake_up_common(q
, mode
, 1, 0, key
);
3194 EXPORT_SYMBOL_GPL(__wake_up_locked_key
);
3197 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
3199 * @mode: which threads
3200 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3201 * @key: opaque value to be passed to wakeup targets
3203 * The sync wakeup differs that the waker knows that it will schedule
3204 * away soon, so while the target thread will be woken up, it will not
3205 * be migrated to another CPU - ie. the two threads are 'synchronized'
3206 * with each other. This can prevent needless bouncing between CPUs.
3208 * On UP it can prevent extra preemption.
3210 * It may be assumed that this function implies a write memory barrier before
3211 * changing the task state if and only if any tasks are woken up.
3213 void __wake_up_sync_key(wait_queue_head_t
*q
, unsigned int mode
,
3214 int nr_exclusive
, void *key
)
3216 unsigned long flags
;
3217 int wake_flags
= WF_SYNC
;
3222 if (unlikely(!nr_exclusive
))
3225 spin_lock_irqsave(&q
->lock
, flags
);
3226 __wake_up_common(q
, mode
, nr_exclusive
, wake_flags
, key
);
3227 spin_unlock_irqrestore(&q
->lock
, flags
);
3229 EXPORT_SYMBOL_GPL(__wake_up_sync_key
);
3232 * __wake_up_sync - see __wake_up_sync_key()
3234 void __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3236 __wake_up_sync_key(q
, mode
, nr_exclusive
, NULL
);
3238 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3241 * complete: - signals a single thread waiting on this completion
3242 * @x: holds the state of this particular completion
3244 * This will wake up a single thread waiting on this completion. Threads will be
3245 * awakened in the same order in which they were queued.
3247 * See also complete_all(), wait_for_completion() and related routines.
3249 * It may be assumed that this function implies a write memory barrier before
3250 * changing the task state if and only if any tasks are woken up.
3252 void complete(struct completion
*x
)
3254 unsigned long flags
;
3256 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3258 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
3259 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3261 EXPORT_SYMBOL(complete
);
3264 * complete_all: - signals all threads waiting on this completion
3265 * @x: holds the state of this particular completion
3267 * This will wake up all threads waiting on this particular completion event.
3269 * It may be assumed that this function implies a write memory barrier before
3270 * changing the task state if and only if any tasks are woken up.
3272 void complete_all(struct completion
*x
)
3274 unsigned long flags
;
3276 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3277 x
->done
+= UINT_MAX
/2;
3278 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
3279 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3281 EXPORT_SYMBOL(complete_all
);
3283 static inline long __sched
3284 do_wait_for_common(struct completion
*x
,
3285 long (*action
)(long), long timeout
, int state
)
3288 DECLARE_WAITQUEUE(wait
, current
);
3290 __add_wait_queue_tail_exclusive(&x
->wait
, &wait
);
3292 if (signal_pending_state(state
, current
)) {
3293 timeout
= -ERESTARTSYS
;
3296 __set_current_state(state
);
3297 spin_unlock_irq(&x
->wait
.lock
);
3298 timeout
= action(timeout
);
3299 spin_lock_irq(&x
->wait
.lock
);
3300 } while (!x
->done
&& timeout
);
3301 __remove_wait_queue(&x
->wait
, &wait
);
3306 return timeout
?: 1;
3309 static inline long __sched
3310 __wait_for_common(struct completion
*x
,
3311 long (*action
)(long), long timeout
, int state
)
3315 spin_lock_irq(&x
->wait
.lock
);
3316 timeout
= do_wait_for_common(x
, action
, timeout
, state
);
3317 spin_unlock_irq(&x
->wait
.lock
);
3322 wait_for_common(struct completion
*x
, long timeout
, int state
)
3324 return __wait_for_common(x
, schedule_timeout
, timeout
, state
);
3328 wait_for_common_io(struct completion
*x
, long timeout
, int state
)
3330 return __wait_for_common(x
, io_schedule_timeout
, timeout
, state
);
3334 * wait_for_completion: - waits for completion of a task
3335 * @x: holds the state of this particular completion
3337 * This waits to be signaled for completion of a specific task. It is NOT
3338 * interruptible and there is no timeout.
3340 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
3341 * and interrupt capability. Also see complete().
3343 void __sched
wait_for_completion(struct completion
*x
)
3345 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3347 EXPORT_SYMBOL(wait_for_completion
);
3350 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
3351 * @x: holds the state of this particular completion
3352 * @timeout: timeout value in jiffies
3354 * This waits for either a completion of a specific task to be signaled or for a
3355 * specified timeout to expire. The timeout is in jiffies. It is not
3358 * The return value is 0 if timed out, and positive (at least 1, or number of
3359 * jiffies left till timeout) if completed.
3361 unsigned long __sched
3362 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3364 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3366 EXPORT_SYMBOL(wait_for_completion_timeout
);
3369 * wait_for_completion_io: - waits for completion of a task
3370 * @x: holds the state of this particular completion
3372 * This waits to be signaled for completion of a specific task. It is NOT
3373 * interruptible and there is no timeout. The caller is accounted as waiting
3376 void __sched
wait_for_completion_io(struct completion
*x
)
3378 wait_for_common_io(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3380 EXPORT_SYMBOL(wait_for_completion_io
);
3383 * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout)
3384 * @x: holds the state of this particular completion
3385 * @timeout: timeout value in jiffies
3387 * This waits for either a completion of a specific task to be signaled or for a
3388 * specified timeout to expire. The timeout is in jiffies. It is not
3389 * interruptible. The caller is accounted as waiting for IO.
3391 * The return value is 0 if timed out, and positive (at least 1, or number of
3392 * jiffies left till timeout) if completed.
3394 unsigned long __sched
3395 wait_for_completion_io_timeout(struct completion
*x
, unsigned long timeout
)
3397 return wait_for_common_io(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3399 EXPORT_SYMBOL(wait_for_completion_io_timeout
);
3402 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
3403 * @x: holds the state of this particular completion
3405 * This waits for completion of a specific task to be signaled. It is
3408 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3410 int __sched
wait_for_completion_interruptible(struct completion
*x
)
3412 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
3413 if (t
== -ERESTARTSYS
)
3417 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3420 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
3421 * @x: holds the state of this particular completion
3422 * @timeout: timeout value in jiffies
3424 * This waits for either a completion of a specific task to be signaled or for a
3425 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
3427 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3428 * positive (at least 1, or number of jiffies left till timeout) if completed.
3431 wait_for_completion_interruptible_timeout(struct completion
*x
,
3432 unsigned long timeout
)
3434 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
3436 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3439 * wait_for_completion_killable: - waits for completion of a task (killable)
3440 * @x: holds the state of this particular completion
3442 * This waits to be signaled for completion of a specific task. It can be
3443 * interrupted by a kill signal.
3445 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3447 int __sched
wait_for_completion_killable(struct completion
*x
)
3449 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
3450 if (t
== -ERESTARTSYS
)
3454 EXPORT_SYMBOL(wait_for_completion_killable
);
3457 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
3458 * @x: holds the state of this particular completion
3459 * @timeout: timeout value in jiffies
3461 * This waits for either a completion of a specific task to be
3462 * signaled or for a specified timeout to expire. It can be
3463 * interrupted by a kill signal. The timeout is in jiffies.
3465 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3466 * positive (at least 1, or number of jiffies left till timeout) if completed.
3469 wait_for_completion_killable_timeout(struct completion
*x
,
3470 unsigned long timeout
)
3472 return wait_for_common(x
, timeout
, TASK_KILLABLE
);
3474 EXPORT_SYMBOL(wait_for_completion_killable_timeout
);
3477 * try_wait_for_completion - try to decrement a completion without blocking
3478 * @x: completion structure
3480 * Returns: 0 if a decrement cannot be done without blocking
3481 * 1 if a decrement succeeded.
3483 * If a completion is being used as a counting completion,
3484 * attempt to decrement the counter without blocking. This
3485 * enables us to avoid waiting if the resource the completion
3486 * is protecting is not available.
3488 bool try_wait_for_completion(struct completion
*x
)
3490 unsigned long flags
;
3493 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3498 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3501 EXPORT_SYMBOL(try_wait_for_completion
);
3504 * completion_done - Test to see if a completion has any waiters
3505 * @x: completion structure
3507 * Returns: 0 if there are waiters (wait_for_completion() in progress)
3508 * 1 if there are no waiters.
3511 bool completion_done(struct completion
*x
)
3513 unsigned long flags
;
3516 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3519 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3522 EXPORT_SYMBOL(completion_done
);
3525 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
3527 unsigned long flags
;
3530 init_waitqueue_entry(&wait
, current
);
3532 __set_current_state(state
);
3534 spin_lock_irqsave(&q
->lock
, flags
);
3535 __add_wait_queue(q
, &wait
);
3536 spin_unlock(&q
->lock
);
3537 timeout
= schedule_timeout(timeout
);
3538 spin_lock_irq(&q
->lock
);
3539 __remove_wait_queue(q
, &wait
);
3540 spin_unlock_irqrestore(&q
->lock
, flags
);
3545 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3547 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3549 EXPORT_SYMBOL(interruptible_sleep_on
);
3552 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3554 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
3556 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3558 void __sched
sleep_on(wait_queue_head_t
*q
)
3560 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3562 EXPORT_SYMBOL(sleep_on
);
3564 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3566 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
3568 EXPORT_SYMBOL(sleep_on_timeout
);
3570 #ifdef CONFIG_RT_MUTEXES
3573 * rt_mutex_setprio - set the current priority of a task
3575 * @prio: prio value (kernel-internal form)
3577 * This function changes the 'effective' priority of a task. It does
3578 * not touch ->normal_prio like __setscheduler().
3580 * Used by the rt_mutex code to implement priority inheritance logic.
3582 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3584 int oldprio
, on_rq
, running
;
3586 const struct sched_class
*prev_class
;
3588 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3590 rq
= __task_rq_lock(p
);
3593 * Idle task boosting is a nono in general. There is one
3594 * exception, when PREEMPT_RT and NOHZ is active:
3596 * The idle task calls get_next_timer_interrupt() and holds
3597 * the timer wheel base->lock on the CPU and another CPU wants
3598 * to access the timer (probably to cancel it). We can safely
3599 * ignore the boosting request, as the idle CPU runs this code
3600 * with interrupts disabled and will complete the lock
3601 * protected section without being interrupted. So there is no
3602 * real need to boost.
3604 if (unlikely(p
== rq
->idle
)) {
3605 WARN_ON(p
!= rq
->curr
);
3606 WARN_ON(p
->pi_blocked_on
);
3610 trace_sched_pi_setprio(p
, prio
);
3612 prev_class
= p
->sched_class
;
3614 running
= task_current(rq
, p
);
3616 dequeue_task(rq
, p
, 0);
3618 p
->sched_class
->put_prev_task(rq
, p
);
3621 p
->sched_class
= &rt_sched_class
;
3623 p
->sched_class
= &fair_sched_class
;
3628 p
->sched_class
->set_curr_task(rq
);
3630 enqueue_task(rq
, p
, oldprio
< prio
? ENQUEUE_HEAD
: 0);
3632 check_class_changed(rq
, p
, prev_class
, oldprio
);
3634 __task_rq_unlock(rq
);
3637 void set_user_nice(struct task_struct
*p
, long nice
)
3639 int old_prio
, delta
, on_rq
;
3640 unsigned long flags
;
3643 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3646 * We have to be careful, if called from sys_setpriority(),
3647 * the task might be in the middle of scheduling on another CPU.
3649 rq
= task_rq_lock(p
, &flags
);
3651 * The RT priorities are set via sched_setscheduler(), but we still
3652 * allow the 'normal' nice value to be set - but as expected
3653 * it wont have any effect on scheduling until the task is
3654 * SCHED_FIFO/SCHED_RR:
3656 if (task_has_rt_policy(p
)) {
3657 p
->static_prio
= NICE_TO_PRIO(nice
);
3662 dequeue_task(rq
, p
, 0);
3664 p
->static_prio
= NICE_TO_PRIO(nice
);
3667 p
->prio
= effective_prio(p
);
3668 delta
= p
->prio
- old_prio
;
3671 enqueue_task(rq
, p
, 0);
3673 * If the task increased its priority or is running and
3674 * lowered its priority, then reschedule its CPU:
3676 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3677 resched_task(rq
->curr
);
3680 task_rq_unlock(rq
, p
, &flags
);
3682 EXPORT_SYMBOL(set_user_nice
);
3685 * can_nice - check if a task can reduce its nice value
3689 int can_nice(const struct task_struct
*p
, const int nice
)
3691 /* convert nice value [19,-20] to rlimit style value [1,40] */
3692 int nice_rlim
= 20 - nice
;
3694 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3695 capable(CAP_SYS_NICE
));
3698 #ifdef __ARCH_WANT_SYS_NICE
3701 * sys_nice - change the priority of the current process.
3702 * @increment: priority increment
3704 * sys_setpriority is a more generic, but much slower function that
3705 * does similar things.
3707 SYSCALL_DEFINE1(nice
, int, increment
)
3712 * Setpriority might change our priority at the same moment.
3713 * We don't have to worry. Conceptually one call occurs first
3714 * and we have a single winner.
3716 if (increment
< -40)
3721 nice
= TASK_NICE(current
) + increment
;
3727 if (increment
< 0 && !can_nice(current
, nice
))
3730 retval
= security_task_setnice(current
, nice
);
3734 set_user_nice(current
, nice
);
3741 * task_prio - return the priority value of a given task.
3742 * @p: the task in question.
3744 * This is the priority value as seen by users in /proc.
3745 * RT tasks are offset by -200. Normal tasks are centered
3746 * around 0, value goes from -16 to +15.
3748 int task_prio(const struct task_struct
*p
)
3750 return p
->prio
- MAX_RT_PRIO
;
3754 * task_nice - return the nice value of a given task.
3755 * @p: the task in question.
3757 int task_nice(const struct task_struct
*p
)
3759 return TASK_NICE(p
);
3761 EXPORT_SYMBOL(task_nice
);
3764 * idle_cpu - is a given cpu idle currently?
3765 * @cpu: the processor in question.
3767 int idle_cpu(int cpu
)
3769 struct rq
*rq
= cpu_rq(cpu
);
3771 if (rq
->curr
!= rq
->idle
)
3778 if (!llist_empty(&rq
->wake_list
))
3786 * idle_task - return the idle task for a given cpu.
3787 * @cpu: the processor in question.
3789 struct task_struct
*idle_task(int cpu
)
3791 return cpu_rq(cpu
)->idle
;
3795 * find_process_by_pid - find a process with a matching PID value.
3796 * @pid: the pid in question.
3798 static struct task_struct
*find_process_by_pid(pid_t pid
)
3800 return pid
? find_task_by_vpid(pid
) : current
;
3803 /* Actually do priority change: must hold rq lock. */
3805 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
3808 p
->rt_priority
= prio
;
3809 p
->normal_prio
= normal_prio(p
);
3810 /* we are holding p->pi_lock already */
3811 p
->prio
= rt_mutex_getprio(p
);
3812 if (rt_prio(p
->prio
))
3813 p
->sched_class
= &rt_sched_class
;
3815 p
->sched_class
= &fair_sched_class
;
3820 * check the target process has a UID that matches the current process's
3822 static bool check_same_owner(struct task_struct
*p
)
3824 const struct cred
*cred
= current_cred(), *pcred
;
3828 pcred
= __task_cred(p
);
3829 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3830 uid_eq(cred
->euid
, pcred
->uid
));
3835 static int __sched_setscheduler(struct task_struct
*p
, int policy
,
3836 const struct sched_param
*param
, bool user
)
3838 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
3839 unsigned long flags
;
3840 const struct sched_class
*prev_class
;
3844 /* may grab non-irq protected spin_locks */
3845 BUG_ON(in_interrupt());
3847 /* double check policy once rq lock held */
3849 reset_on_fork
= p
->sched_reset_on_fork
;
3850 policy
= oldpolicy
= p
->policy
;
3852 reset_on_fork
= !!(policy
& SCHED_RESET_ON_FORK
);
3853 policy
&= ~SCHED_RESET_ON_FORK
;
3855 if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3856 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
3857 policy
!= SCHED_IDLE
)
3862 * Valid priorities for SCHED_FIFO and SCHED_RR are
3863 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3864 * SCHED_BATCH and SCHED_IDLE is 0.
3866 if (param
->sched_priority
< 0 ||
3867 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3868 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3870 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
3874 * Allow unprivileged RT tasks to decrease priority:
3876 if (user
&& !capable(CAP_SYS_NICE
)) {
3877 if (rt_policy(policy
)) {
3878 unsigned long rlim_rtprio
=
3879 task_rlimit(p
, RLIMIT_RTPRIO
);
3881 /* can't set/change the rt policy */
3882 if (policy
!= p
->policy
&& !rlim_rtprio
)
3885 /* can't increase priority */
3886 if (param
->sched_priority
> p
->rt_priority
&&
3887 param
->sched_priority
> rlim_rtprio
)
3892 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3893 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3895 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
3896 if (!can_nice(p
, TASK_NICE(p
)))
3900 /* can't change other user's priorities */
3901 if (!check_same_owner(p
))
3904 /* Normal users shall not reset the sched_reset_on_fork flag */
3905 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3910 retval
= security_task_setscheduler(p
);
3916 * make sure no PI-waiters arrive (or leave) while we are
3917 * changing the priority of the task:
3919 * To be able to change p->policy safely, the appropriate
3920 * runqueue lock must be held.
3922 rq
= task_rq_lock(p
, &flags
);
3925 * Changing the policy of the stop threads its a very bad idea
3927 if (p
== rq
->stop
) {
3928 task_rq_unlock(rq
, p
, &flags
);
3933 * If not changing anything there's no need to proceed further:
3935 if (unlikely(policy
== p
->policy
&& (!rt_policy(policy
) ||
3936 param
->sched_priority
== p
->rt_priority
))) {
3937 task_rq_unlock(rq
, p
, &flags
);
3941 #ifdef CONFIG_RT_GROUP_SCHED
3944 * Do not allow realtime tasks into groups that have no runtime
3947 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
3948 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
3949 !task_group_is_autogroup(task_group(p
))) {
3950 task_rq_unlock(rq
, p
, &flags
);
3956 /* recheck policy now with rq lock held */
3957 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3958 policy
= oldpolicy
= -1;
3959 task_rq_unlock(rq
, p
, &flags
);
3963 running
= task_current(rq
, p
);
3965 dequeue_task(rq
, p
, 0);
3967 p
->sched_class
->put_prev_task(rq
, p
);
3969 p
->sched_reset_on_fork
= reset_on_fork
;
3972 prev_class
= p
->sched_class
;
3973 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
3976 p
->sched_class
->set_curr_task(rq
);
3978 enqueue_task(rq
, p
, 0);
3980 check_class_changed(rq
, p
, prev_class
, oldprio
);
3981 task_rq_unlock(rq
, p
, &flags
);
3983 rt_mutex_adjust_pi(p
);
3989 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3990 * @p: the task in question.
3991 * @policy: new policy.
3992 * @param: structure containing the new RT priority.
3994 * NOTE that the task may be already dead.
3996 int sched_setscheduler(struct task_struct
*p
, int policy
,
3997 const struct sched_param
*param
)
3999 return __sched_setscheduler(p
, policy
, param
, true);
4001 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4004 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4005 * @p: the task in question.
4006 * @policy: new policy.
4007 * @param: structure containing the new RT priority.
4009 * Just like sched_setscheduler, only don't bother checking if the
4010 * current context has permission. For example, this is needed in
4011 * stop_machine(): we create temporary high priority worker threads,
4012 * but our caller might not have that capability.
4014 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
4015 const struct sched_param
*param
)
4017 return __sched_setscheduler(p
, policy
, param
, false);
4021 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4023 struct sched_param lparam
;
4024 struct task_struct
*p
;
4027 if (!param
|| pid
< 0)
4029 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4034 p
= find_process_by_pid(pid
);
4036 retval
= sched_setscheduler(p
, policy
, &lparam
);
4043 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4044 * @pid: the pid in question.
4045 * @policy: new policy.
4046 * @param: structure containing the new RT priority.
4048 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
4049 struct sched_param __user
*, param
)
4051 /* negative values for policy are not valid */
4055 return do_sched_setscheduler(pid
, policy
, param
);
4059 * sys_sched_setparam - set/change the RT priority of a thread
4060 * @pid: the pid in question.
4061 * @param: structure containing the new RT priority.
4063 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4065 return do_sched_setscheduler(pid
, -1, param
);
4069 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4070 * @pid: the pid in question.
4072 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
4074 struct task_struct
*p
;
4082 p
= find_process_by_pid(pid
);
4084 retval
= security_task_getscheduler(p
);
4087 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
4094 * sys_sched_getparam - get the RT priority of a thread
4095 * @pid: the pid in question.
4096 * @param: structure containing the RT priority.
4098 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4100 struct sched_param lp
;
4101 struct task_struct
*p
;
4104 if (!param
|| pid
< 0)
4108 p
= find_process_by_pid(pid
);
4113 retval
= security_task_getscheduler(p
);
4117 lp
.sched_priority
= p
->rt_priority
;
4121 * This one might sleep, we cannot do it with a spinlock held ...
4123 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4132 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
4134 cpumask_var_t cpus_allowed
, new_mask
;
4135 struct task_struct
*p
;
4141 p
= find_process_by_pid(pid
);
4148 /* Prevent p going away */
4152 if (p
->flags
& PF_NO_SETAFFINITY
) {
4156 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4160 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4162 goto out_free_cpus_allowed
;
4165 if (!check_same_owner(p
)) {
4167 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4174 retval
= security_task_setscheduler(p
);
4178 cpuset_cpus_allowed(p
, cpus_allowed
);
4179 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4181 retval
= set_cpus_allowed_ptr(p
, new_mask
);
4184 cpuset_cpus_allowed(p
, cpus_allowed
);
4185 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4187 * We must have raced with a concurrent cpuset
4188 * update. Just reset the cpus_allowed to the
4189 * cpuset's cpus_allowed
4191 cpumask_copy(new_mask
, cpus_allowed
);
4196 free_cpumask_var(new_mask
);
4197 out_free_cpus_allowed
:
4198 free_cpumask_var(cpus_allowed
);
4205 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4206 struct cpumask
*new_mask
)
4208 if (len
< cpumask_size())
4209 cpumask_clear(new_mask
);
4210 else if (len
> cpumask_size())
4211 len
= cpumask_size();
4213 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4217 * sys_sched_setaffinity - set the cpu affinity of a process
4218 * @pid: pid of the process
4219 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4220 * @user_mask_ptr: user-space pointer to the new cpu mask
4222 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4223 unsigned long __user
*, user_mask_ptr
)
4225 cpumask_var_t new_mask
;
4228 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4231 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4233 retval
= sched_setaffinity(pid
, new_mask
);
4234 free_cpumask_var(new_mask
);
4238 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4240 struct task_struct
*p
;
4241 unsigned long flags
;
4248 p
= find_process_by_pid(pid
);
4252 retval
= security_task_getscheduler(p
);
4256 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4257 cpumask_and(mask
, &p
->cpus_allowed
, cpu_online_mask
);
4258 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4268 * sys_sched_getaffinity - get the cpu affinity of a process
4269 * @pid: pid of the process
4270 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4271 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4273 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4274 unsigned long __user
*, user_mask_ptr
)
4279 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4281 if (len
& (sizeof(unsigned long)-1))
4284 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4287 ret
= sched_getaffinity(pid
, mask
);
4289 size_t retlen
= min_t(size_t, len
, cpumask_size());
4291 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4296 free_cpumask_var(mask
);
4302 * sys_sched_yield - yield the current processor to other threads.
4304 * This function yields the current CPU to other tasks. If there are no
4305 * other threads running on this CPU then this function will return.
4307 SYSCALL_DEFINE0(sched_yield
)
4309 struct rq
*rq
= this_rq_lock();
4311 schedstat_inc(rq
, yld_count
);
4312 current
->sched_class
->yield_task(rq
);
4315 * Since we are going to call schedule() anyway, there's
4316 * no need to preempt or enable interrupts:
4318 __release(rq
->lock
);
4319 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4320 do_raw_spin_unlock(&rq
->lock
);
4321 sched_preempt_enable_no_resched();
4328 static inline int should_resched(void)
4330 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE
);
4333 static void __cond_resched(void)
4335 add_preempt_count(PREEMPT_ACTIVE
);
4337 sub_preempt_count(PREEMPT_ACTIVE
);
4340 int __sched
_cond_resched(void)
4342 if (should_resched()) {
4348 EXPORT_SYMBOL(_cond_resched
);
4351 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4352 * call schedule, and on return reacquire the lock.
4354 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4355 * operations here to prevent schedule() from being called twice (once via
4356 * spin_unlock(), once by hand).
4358 int __cond_resched_lock(spinlock_t
*lock
)
4360 int resched
= should_resched();
4363 lockdep_assert_held(lock
);
4365 if (spin_needbreak(lock
) || resched
) {
4376 EXPORT_SYMBOL(__cond_resched_lock
);
4378 int __sched
__cond_resched_softirq(void)
4380 BUG_ON(!in_softirq());
4382 if (should_resched()) {
4390 EXPORT_SYMBOL(__cond_resched_softirq
);
4393 * yield - yield the current processor to other threads.
4395 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4397 * The scheduler is at all times free to pick the calling task as the most
4398 * eligible task to run, if removing the yield() call from your code breaks
4399 * it, its already broken.
4401 * Typical broken usage is:
4406 * where one assumes that yield() will let 'the other' process run that will
4407 * make event true. If the current task is a SCHED_FIFO task that will never
4408 * happen. Never use yield() as a progress guarantee!!
4410 * If you want to use yield() to wait for something, use wait_event().
4411 * If you want to use yield() to be 'nice' for others, use cond_resched().
4412 * If you still want to use yield(), do not!
4414 void __sched
yield(void)
4416 set_current_state(TASK_RUNNING
);
4419 EXPORT_SYMBOL(yield
);
4422 * yield_to - yield the current processor to another thread in
4423 * your thread group, or accelerate that thread toward the
4424 * processor it's on.
4426 * @preempt: whether task preemption is allowed or not
4428 * It's the caller's job to ensure that the target task struct
4429 * can't go away on us before we can do any checks.
4432 * true (>0) if we indeed boosted the target task.
4433 * false (0) if we failed to boost the target.
4434 * -ESRCH if there's no task to yield to.
4436 bool __sched
yield_to(struct task_struct
*p
, bool preempt
)
4438 struct task_struct
*curr
= current
;
4439 struct rq
*rq
, *p_rq
;
4440 unsigned long flags
;
4443 local_irq_save(flags
);
4449 * If we're the only runnable task on the rq and target rq also
4450 * has only one task, there's absolutely no point in yielding.
4452 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4457 double_rq_lock(rq
, p_rq
);
4458 while (task_rq(p
) != p_rq
) {
4459 double_rq_unlock(rq
, p_rq
);
4463 if (!curr
->sched_class
->yield_to_task
)
4466 if (curr
->sched_class
!= p
->sched_class
)
4469 if (task_running(p_rq
, p
) || p
->state
)
4472 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4474 schedstat_inc(rq
, yld_count
);
4476 * Make p's CPU reschedule; pick_next_entity takes care of
4479 if (preempt
&& rq
!= p_rq
)
4480 resched_task(p_rq
->curr
);
4484 double_rq_unlock(rq
, p_rq
);
4486 local_irq_restore(flags
);
4493 EXPORT_SYMBOL_GPL(yield_to
);
4496 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4497 * that process accounting knows that this is a task in IO wait state.
4499 void __sched
io_schedule(void)
4501 struct rq
*rq
= raw_rq();
4503 delayacct_blkio_start();
4504 atomic_inc(&rq
->nr_iowait
);
4505 blk_flush_plug(current
);
4506 current
->in_iowait
= 1;
4508 current
->in_iowait
= 0;
4509 atomic_dec(&rq
->nr_iowait
);
4510 delayacct_blkio_end();
4512 EXPORT_SYMBOL(io_schedule
);
4514 long __sched
io_schedule_timeout(long timeout
)
4516 struct rq
*rq
= raw_rq();
4519 delayacct_blkio_start();
4520 atomic_inc(&rq
->nr_iowait
);
4521 blk_flush_plug(current
);
4522 current
->in_iowait
= 1;
4523 ret
= schedule_timeout(timeout
);
4524 current
->in_iowait
= 0;
4525 atomic_dec(&rq
->nr_iowait
);
4526 delayacct_blkio_end();
4531 * sys_sched_get_priority_max - return maximum RT priority.
4532 * @policy: scheduling class.
4534 * this syscall returns the maximum rt_priority that can be used
4535 * by a given scheduling class.
4537 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
4544 ret
= MAX_USER_RT_PRIO
-1;
4556 * sys_sched_get_priority_min - return minimum RT priority.
4557 * @policy: scheduling class.
4559 * this syscall returns the minimum rt_priority that can be used
4560 * by a given scheduling class.
4562 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
4580 * sys_sched_rr_get_interval - return the default timeslice of a process.
4581 * @pid: pid of the process.
4582 * @interval: userspace pointer to the timeslice value.
4584 * this syscall writes the default timeslice value of a given process
4585 * into the user-space timespec buffer. A value of '0' means infinity.
4587 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
4588 struct timespec __user
*, interval
)
4590 struct task_struct
*p
;
4591 unsigned int time_slice
;
4592 unsigned long flags
;
4602 p
= find_process_by_pid(pid
);
4606 retval
= security_task_getscheduler(p
);
4610 rq
= task_rq_lock(p
, &flags
);
4611 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
4612 task_rq_unlock(rq
, p
, &flags
);
4615 jiffies_to_timespec(time_slice
, &t
);
4616 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4624 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
4626 void sched_show_task(struct task_struct
*p
)
4628 unsigned long free
= 0;
4632 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4633 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
4634 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4635 #if BITS_PER_LONG == 32
4636 if (state
== TASK_RUNNING
)
4637 printk(KERN_CONT
" running ");
4639 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4641 if (state
== TASK_RUNNING
)
4642 printk(KERN_CONT
" running task ");
4644 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4646 #ifdef CONFIG_DEBUG_STACK_USAGE
4647 free
= stack_not_used(p
);
4650 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
4652 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
4653 task_pid_nr(p
), ppid
,
4654 (unsigned long)task_thread_info(p
)->flags
);
4656 print_worker_info(KERN_INFO
, p
);
4657 show_stack(p
, NULL
);
4660 void show_state_filter(unsigned long state_filter
)
4662 struct task_struct
*g
, *p
;
4664 #if BITS_PER_LONG == 32
4666 " task PC stack pid father\n");
4669 " task PC stack pid father\n");
4672 do_each_thread(g
, p
) {
4674 * reset the NMI-timeout, listing all files on a slow
4675 * console might take a lot of time:
4677 touch_nmi_watchdog();
4678 if (!state_filter
|| (p
->state
& state_filter
))
4680 } while_each_thread(g
, p
);
4682 touch_all_softlockup_watchdogs();
4684 #ifdef CONFIG_SCHED_DEBUG
4685 sysrq_sched_debug_show();
4689 * Only show locks if all tasks are dumped:
4692 debug_show_all_locks();
4695 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4697 idle
->sched_class
= &idle_sched_class
;
4701 * init_idle - set up an idle thread for a given CPU
4702 * @idle: task in question
4703 * @cpu: cpu the idle task belongs to
4705 * NOTE: this function does not set the idle thread's NEED_RESCHED
4706 * flag, to make booting more robust.
4708 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4710 struct rq
*rq
= cpu_rq(cpu
);
4711 unsigned long flags
;
4713 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4716 idle
->state
= TASK_RUNNING
;
4717 idle
->se
.exec_start
= sched_clock();
4719 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
4721 * We're having a chicken and egg problem, even though we are
4722 * holding rq->lock, the cpu isn't yet set to this cpu so the
4723 * lockdep check in task_group() will fail.
4725 * Similar case to sched_fork(). / Alternatively we could
4726 * use task_rq_lock() here and obtain the other rq->lock.
4731 __set_task_cpu(idle
, cpu
);
4734 rq
->curr
= rq
->idle
= idle
;
4735 #if defined(CONFIG_SMP)
4738 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4740 /* Set the preempt count _outside_ the spinlocks! */
4741 task_thread_info(idle
)->preempt_count
= 0;
4744 * The idle tasks have their own, simple scheduling class:
4746 idle
->sched_class
= &idle_sched_class
;
4747 ftrace_graph_init_idle_task(idle
, cpu
);
4748 vtime_init_idle(idle
);
4749 #if defined(CONFIG_SMP)
4750 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
4755 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
4757 if (p
->sched_class
&& p
->sched_class
->set_cpus_allowed
)
4758 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
4760 cpumask_copy(&p
->cpus_allowed
, new_mask
);
4761 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
4765 * This is how migration works:
4767 * 1) we invoke migration_cpu_stop() on the target CPU using
4769 * 2) stopper starts to run (implicitly forcing the migrated thread
4771 * 3) it checks whether the migrated task is still in the wrong runqueue.
4772 * 4) if it's in the wrong runqueue then the migration thread removes
4773 * it and puts it into the right queue.
4774 * 5) stopper completes and stop_one_cpu() returns and the migration
4779 * Change a given task's CPU affinity. Migrate the thread to a
4780 * proper CPU and schedule it away if the CPU it's executing on
4781 * is removed from the allowed bitmask.
4783 * NOTE: the caller must have a valid reference to the task, the
4784 * task must not exit() & deallocate itself prematurely. The
4785 * call is not atomic; no spinlocks may be held.
4787 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
4789 unsigned long flags
;
4791 unsigned int dest_cpu
;
4794 rq
= task_rq_lock(p
, &flags
);
4796 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
4799 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
4804 do_set_cpus_allowed(p
, new_mask
);
4806 /* Can the task run on the task's current CPU? If so, we're done */
4807 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
4810 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
4812 struct migration_arg arg
= { p
, dest_cpu
};
4813 /* Need help from migration thread: drop lock and wait. */
4814 task_rq_unlock(rq
, p
, &flags
);
4815 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
4816 tlb_migrate_finish(p
->mm
);
4820 task_rq_unlock(rq
, p
, &flags
);
4824 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
4827 * Move (not current) task off this cpu, onto dest cpu. We're doing
4828 * this because either it can't run here any more (set_cpus_allowed()
4829 * away from this CPU, or CPU going down), or because we're
4830 * attempting to rebalance this task on exec (sched_exec).
4832 * So we race with normal scheduler movements, but that's OK, as long
4833 * as the task is no longer on this CPU.
4835 * Returns non-zero if task was successfully migrated.
4837 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4839 struct rq
*rq_dest
, *rq_src
;
4842 if (unlikely(!cpu_active(dest_cpu
)))
4845 rq_src
= cpu_rq(src_cpu
);
4846 rq_dest
= cpu_rq(dest_cpu
);
4848 raw_spin_lock(&p
->pi_lock
);
4849 double_rq_lock(rq_src
, rq_dest
);
4850 /* Already moved. */
4851 if (task_cpu(p
) != src_cpu
)
4853 /* Affinity changed (again). */
4854 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
4858 * If we're not on a rq, the next wake-up will ensure we're
4862 dequeue_task(rq_src
, p
, 0);
4863 set_task_cpu(p
, dest_cpu
);
4864 enqueue_task(rq_dest
, p
, 0);
4865 check_preempt_curr(rq_dest
, p
, 0);
4870 double_rq_unlock(rq_src
, rq_dest
);
4871 raw_spin_unlock(&p
->pi_lock
);
4876 * migration_cpu_stop - this will be executed by a highprio stopper thread
4877 * and performs thread migration by bumping thread off CPU then
4878 * 'pushing' onto another runqueue.
4880 static int migration_cpu_stop(void *data
)
4882 struct migration_arg
*arg
= data
;
4885 * The original target cpu might have gone down and we might
4886 * be on another cpu but it doesn't matter.
4888 local_irq_disable();
4889 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
4894 #ifdef CONFIG_HOTPLUG_CPU
4897 * Ensures that the idle task is using init_mm right before its cpu goes
4900 void idle_task_exit(void)
4902 struct mm_struct
*mm
= current
->active_mm
;
4904 BUG_ON(cpu_online(smp_processor_id()));
4907 switch_mm(mm
, &init_mm
, current
);
4912 * Since this CPU is going 'away' for a while, fold any nr_active delta
4913 * we might have. Assumes we're called after migrate_tasks() so that the
4914 * nr_active count is stable.
4916 * Also see the comment "Global load-average calculations".
4918 static void calc_load_migrate(struct rq
*rq
)
4920 long delta
= calc_load_fold_active(rq
);
4922 atomic_long_add(delta
, &calc_load_tasks
);
4926 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4927 * try_to_wake_up()->select_task_rq().
4929 * Called with rq->lock held even though we'er in stop_machine() and
4930 * there's no concurrency possible, we hold the required locks anyway
4931 * because of lock validation efforts.
4933 static void migrate_tasks(unsigned int dead_cpu
)
4935 struct rq
*rq
= cpu_rq(dead_cpu
);
4936 struct task_struct
*next
, *stop
= rq
->stop
;
4940 * Fudge the rq selection such that the below task selection loop
4941 * doesn't get stuck on the currently eligible stop task.
4943 * We're currently inside stop_machine() and the rq is either stuck
4944 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4945 * either way we should never end up calling schedule() until we're
4952 * There's this thread running, bail when that's the only
4955 if (rq
->nr_running
== 1)
4958 next
= pick_next_task(rq
);
4960 next
->sched_class
->put_prev_task(rq
, next
);
4962 /* Find suitable destination for @next, with force if needed. */
4963 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
4964 raw_spin_unlock(&rq
->lock
);
4966 __migrate_task(next
, dead_cpu
, dest_cpu
);
4968 raw_spin_lock(&rq
->lock
);
4974 #endif /* CONFIG_HOTPLUG_CPU */
4976 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4978 static struct ctl_table sd_ctl_dir
[] = {
4980 .procname
= "sched_domain",
4986 static struct ctl_table sd_ctl_root
[] = {
4988 .procname
= "kernel",
4990 .child
= sd_ctl_dir
,
4995 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
4997 struct ctl_table
*entry
=
4998 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5003 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5005 struct ctl_table
*entry
;
5008 * In the intermediate directories, both the child directory and
5009 * procname are dynamically allocated and could fail but the mode
5010 * will always be set. In the lowest directory the names are
5011 * static strings and all have proc handlers.
5013 for (entry
= *tablep
; entry
->mode
; entry
++) {
5015 sd_free_ctl_entry(&entry
->child
);
5016 if (entry
->proc_handler
== NULL
)
5017 kfree(entry
->procname
);
5024 static int min_load_idx
= 0;
5025 static int max_load_idx
= CPU_LOAD_IDX_MAX
-1;
5028 set_table_entry(struct ctl_table
*entry
,
5029 const char *procname
, void *data
, int maxlen
,
5030 umode_t mode
, proc_handler
*proc_handler
,
5033 entry
->procname
= procname
;
5035 entry
->maxlen
= maxlen
;
5037 entry
->proc_handler
= proc_handler
;
5040 entry
->extra1
= &min_load_idx
;
5041 entry
->extra2
= &max_load_idx
;
5045 static struct ctl_table
*
5046 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5048 struct ctl_table
*table
= sd_alloc_ctl_entry(13);
5053 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5054 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5055 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5056 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5057 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5058 sizeof(int), 0644, proc_dointvec_minmax
, true);
5059 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5060 sizeof(int), 0644, proc_dointvec_minmax
, true);
5061 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5062 sizeof(int), 0644, proc_dointvec_minmax
, true);
5063 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5064 sizeof(int), 0644, proc_dointvec_minmax
, true);
5065 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5066 sizeof(int), 0644, proc_dointvec_minmax
, true);
5067 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5068 sizeof(int), 0644, proc_dointvec_minmax
, false);
5069 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5070 sizeof(int), 0644, proc_dointvec_minmax
, false);
5071 set_table_entry(&table
[9], "cache_nice_tries",
5072 &sd
->cache_nice_tries
,
5073 sizeof(int), 0644, proc_dointvec_minmax
, false);
5074 set_table_entry(&table
[10], "flags", &sd
->flags
,
5075 sizeof(int), 0644, proc_dointvec_minmax
, false);
5076 set_table_entry(&table
[11], "name", sd
->name
,
5077 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
5078 /* &table[12] is terminator */
5083 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5085 struct ctl_table
*entry
, *table
;
5086 struct sched_domain
*sd
;
5087 int domain_num
= 0, i
;
5090 for_each_domain(cpu
, sd
)
5092 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5097 for_each_domain(cpu
, sd
) {
5098 snprintf(buf
, 32, "domain%d", i
);
5099 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5101 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5108 static struct ctl_table_header
*sd_sysctl_header
;
5109 static void register_sched_domain_sysctl(void)
5111 int i
, cpu_num
= num_possible_cpus();
5112 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5115 WARN_ON(sd_ctl_dir
[0].child
);
5116 sd_ctl_dir
[0].child
= entry
;
5121 for_each_possible_cpu(i
) {
5122 snprintf(buf
, 32, "cpu%d", i
);
5123 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5125 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5129 WARN_ON(sd_sysctl_header
);
5130 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5133 /* may be called multiple times per register */
5134 static void unregister_sched_domain_sysctl(void)
5136 if (sd_sysctl_header
)
5137 unregister_sysctl_table(sd_sysctl_header
);
5138 sd_sysctl_header
= NULL
;
5139 if (sd_ctl_dir
[0].child
)
5140 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5143 static void register_sched_domain_sysctl(void)
5146 static void unregister_sched_domain_sysctl(void)
5151 static void set_rq_online(struct rq
*rq
)
5154 const struct sched_class
*class;
5156 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5159 for_each_class(class) {
5160 if (class->rq_online
)
5161 class->rq_online(rq
);
5166 static void set_rq_offline(struct rq
*rq
)
5169 const struct sched_class
*class;
5171 for_each_class(class) {
5172 if (class->rq_offline
)
5173 class->rq_offline(rq
);
5176 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5182 * migration_call - callback that gets triggered when a CPU is added.
5183 * Here we can start up the necessary migration thread for the new CPU.
5185 static int __cpuinit
5186 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5188 int cpu
= (long)hcpu
;
5189 unsigned long flags
;
5190 struct rq
*rq
= cpu_rq(cpu
);
5192 switch (action
& ~CPU_TASKS_FROZEN
) {
5194 case CPU_UP_PREPARE
:
5195 rq
->calc_load_update
= calc_load_update
;
5199 /* Update our root-domain */
5200 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5202 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5206 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5209 #ifdef CONFIG_HOTPLUG_CPU
5211 sched_ttwu_pending();
5212 /* Update our root-domain */
5213 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5215 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5219 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
5220 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5224 calc_load_migrate(rq
);
5229 update_max_interval();
5235 * Register at high priority so that task migration (migrate_all_tasks)
5236 * happens before everything else. This has to be lower priority than
5237 * the notifier in the perf_event subsystem, though.
5239 static struct notifier_block __cpuinitdata migration_notifier
= {
5240 .notifier_call
= migration_call
,
5241 .priority
= CPU_PRI_MIGRATION
,
5244 static int __cpuinit
sched_cpu_active(struct notifier_block
*nfb
,
5245 unsigned long action
, void *hcpu
)
5247 switch (action
& ~CPU_TASKS_FROZEN
) {
5249 case CPU_DOWN_FAILED
:
5250 set_cpu_active((long)hcpu
, true);
5257 static int __cpuinit
sched_cpu_inactive(struct notifier_block
*nfb
,
5258 unsigned long action
, void *hcpu
)
5260 switch (action
& ~CPU_TASKS_FROZEN
) {
5261 case CPU_DOWN_PREPARE
:
5262 set_cpu_active((long)hcpu
, false);
5269 static int __init
migration_init(void)
5271 void *cpu
= (void *)(long)smp_processor_id();
5274 /* Initialize migration for the boot CPU */
5275 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5276 BUG_ON(err
== NOTIFY_BAD
);
5277 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5278 register_cpu_notifier(&migration_notifier
);
5280 /* Register cpu active notifiers */
5281 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
5282 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
5286 early_initcall(migration_init
);
5291 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5293 #ifdef CONFIG_SCHED_DEBUG
5295 static __read_mostly
int sched_debug_enabled
;
5297 static int __init
sched_debug_setup(char *str
)
5299 sched_debug_enabled
= 1;
5303 early_param("sched_debug", sched_debug_setup
);
5305 static inline bool sched_debug(void)
5307 return sched_debug_enabled
;
5310 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5311 struct cpumask
*groupmask
)
5313 struct sched_group
*group
= sd
->groups
;
5316 cpulist_scnprintf(str
, sizeof(str
), sched_domain_span(sd
));
5317 cpumask_clear(groupmask
);
5319 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5321 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5322 printk("does not load-balance\n");
5324 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5329 printk(KERN_CONT
"span %s level %s\n", str
, sd
->name
);
5331 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5332 printk(KERN_ERR
"ERROR: domain->span does not contain "
5335 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5336 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5340 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5344 printk(KERN_ERR
"ERROR: group is NULL\n");
5349 * Even though we initialize ->power to something semi-sane,
5350 * we leave power_orig unset. This allows us to detect if
5351 * domain iteration is still funny without causing /0 traps.
5353 if (!group
->sgp
->power_orig
) {
5354 printk(KERN_CONT
"\n");
5355 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5360 if (!cpumask_weight(sched_group_cpus(group
))) {
5361 printk(KERN_CONT
"\n");
5362 printk(KERN_ERR
"ERROR: empty group\n");
5366 if (!(sd
->flags
& SD_OVERLAP
) &&
5367 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5368 printk(KERN_CONT
"\n");
5369 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5373 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5375 cpulist_scnprintf(str
, sizeof(str
), sched_group_cpus(group
));
5377 printk(KERN_CONT
" %s", str
);
5378 if (group
->sgp
->power
!= SCHED_POWER_SCALE
) {
5379 printk(KERN_CONT
" (cpu_power = %d)",
5383 group
= group
->next
;
5384 } while (group
!= sd
->groups
);
5385 printk(KERN_CONT
"\n");
5387 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5388 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5391 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5392 printk(KERN_ERR
"ERROR: parent span is not a superset "
5393 "of domain->span\n");
5397 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5401 if (!sched_debug_enabled
)
5405 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5409 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5412 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5420 #else /* !CONFIG_SCHED_DEBUG */
5421 # define sched_domain_debug(sd, cpu) do { } while (0)
5422 static inline bool sched_debug(void)
5426 #endif /* CONFIG_SCHED_DEBUG */
5428 static int sd_degenerate(struct sched_domain
*sd
)
5430 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5433 /* Following flags need at least 2 groups */
5434 if (sd
->flags
& (SD_LOAD_BALANCE
|
5435 SD_BALANCE_NEWIDLE
|
5439 SD_SHARE_PKG_RESOURCES
)) {
5440 if (sd
->groups
!= sd
->groups
->next
)
5444 /* Following flags don't use groups */
5445 if (sd
->flags
& (SD_WAKE_AFFINE
))
5452 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5454 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5456 if (sd_degenerate(parent
))
5459 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5462 /* Flags needing groups don't count if only 1 group in parent */
5463 if (parent
->groups
== parent
->groups
->next
) {
5464 pflags
&= ~(SD_LOAD_BALANCE
|
5465 SD_BALANCE_NEWIDLE
|
5469 SD_SHARE_PKG_RESOURCES
);
5470 if (nr_node_ids
== 1)
5471 pflags
&= ~SD_SERIALIZE
;
5473 if (~cflags
& pflags
)
5479 static void free_rootdomain(struct rcu_head
*rcu
)
5481 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5483 cpupri_cleanup(&rd
->cpupri
);
5484 free_cpumask_var(rd
->rto_mask
);
5485 free_cpumask_var(rd
->online
);
5486 free_cpumask_var(rd
->span
);
5490 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5492 struct root_domain
*old_rd
= NULL
;
5493 unsigned long flags
;
5495 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5500 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5503 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5506 * If we dont want to free the old_rt yet then
5507 * set old_rd to NULL to skip the freeing later
5510 if (!atomic_dec_and_test(&old_rd
->refcount
))
5514 atomic_inc(&rd
->refcount
);
5517 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5518 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5521 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5524 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5527 static int init_rootdomain(struct root_domain
*rd
)
5529 memset(rd
, 0, sizeof(*rd
));
5531 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5533 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5535 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5538 if (cpupri_init(&rd
->cpupri
) != 0)
5543 free_cpumask_var(rd
->rto_mask
);
5545 free_cpumask_var(rd
->online
);
5547 free_cpumask_var(rd
->span
);
5553 * By default the system creates a single root-domain with all cpus as
5554 * members (mimicking the global state we have today).
5556 struct root_domain def_root_domain
;
5558 static void init_defrootdomain(void)
5560 init_rootdomain(&def_root_domain
);
5562 atomic_set(&def_root_domain
.refcount
, 1);
5565 static struct root_domain
*alloc_rootdomain(void)
5567 struct root_domain
*rd
;
5569 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
5573 if (init_rootdomain(rd
) != 0) {
5581 static void free_sched_groups(struct sched_group
*sg
, int free_sgp
)
5583 struct sched_group
*tmp
, *first
;
5592 if (free_sgp
&& atomic_dec_and_test(&sg
->sgp
->ref
))
5597 } while (sg
!= first
);
5600 static void free_sched_domain(struct rcu_head
*rcu
)
5602 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
5605 * If its an overlapping domain it has private groups, iterate and
5608 if (sd
->flags
& SD_OVERLAP
) {
5609 free_sched_groups(sd
->groups
, 1);
5610 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
5611 kfree(sd
->groups
->sgp
);
5617 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
5619 call_rcu(&sd
->rcu
, free_sched_domain
);
5622 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
5624 for (; sd
; sd
= sd
->parent
)
5625 destroy_sched_domain(sd
, cpu
);
5629 * Keep a special pointer to the highest sched_domain that has
5630 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5631 * allows us to avoid some pointer chasing select_idle_sibling().
5633 * Also keep a unique ID per domain (we use the first cpu number in
5634 * the cpumask of the domain), this allows us to quickly tell if
5635 * two cpus are in the same cache domain, see cpus_share_cache().
5637 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
5638 DEFINE_PER_CPU(int, sd_llc_id
);
5640 static void update_top_cache_domain(int cpu
)
5642 struct sched_domain
*sd
;
5645 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
5647 id
= cpumask_first(sched_domain_span(sd
));
5649 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
5650 per_cpu(sd_llc_id
, cpu
) = id
;
5654 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5655 * hold the hotplug lock.
5658 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
5660 struct rq
*rq
= cpu_rq(cpu
);
5661 struct sched_domain
*tmp
;
5663 /* Remove the sched domains which do not contribute to scheduling. */
5664 for (tmp
= sd
; tmp
; ) {
5665 struct sched_domain
*parent
= tmp
->parent
;
5669 if (sd_parent_degenerate(tmp
, parent
)) {
5670 tmp
->parent
= parent
->parent
;
5672 parent
->parent
->child
= tmp
;
5673 destroy_sched_domain(parent
, cpu
);
5678 if (sd
&& sd_degenerate(sd
)) {
5681 destroy_sched_domain(tmp
, cpu
);
5686 sched_domain_debug(sd
, cpu
);
5688 rq_attach_root(rq
, rd
);
5690 rcu_assign_pointer(rq
->sd
, sd
);
5691 destroy_sched_domains(tmp
, cpu
);
5693 update_top_cache_domain(cpu
);
5696 /* cpus with isolated domains */
5697 static cpumask_var_t cpu_isolated_map
;
5699 /* Setup the mask of cpus configured for isolated domains */
5700 static int __init
isolated_cpu_setup(char *str
)
5702 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
5703 cpulist_parse(str
, cpu_isolated_map
);
5707 __setup("isolcpus=", isolated_cpu_setup
);
5709 static const struct cpumask
*cpu_cpu_mask(int cpu
)
5711 return cpumask_of_node(cpu_to_node(cpu
));
5715 struct sched_domain
**__percpu sd
;
5716 struct sched_group
**__percpu sg
;
5717 struct sched_group_power
**__percpu sgp
;
5721 struct sched_domain
** __percpu sd
;
5722 struct root_domain
*rd
;
5732 struct sched_domain_topology_level
;
5734 typedef struct sched_domain
*(*sched_domain_init_f
)(struct sched_domain_topology_level
*tl
, int cpu
);
5735 typedef const struct cpumask
*(*sched_domain_mask_f
)(int cpu
);
5737 #define SDTL_OVERLAP 0x01
5739 struct sched_domain_topology_level
{
5740 sched_domain_init_f init
;
5741 sched_domain_mask_f mask
;
5744 struct sd_data data
;
5748 * Build an iteration mask that can exclude certain CPUs from the upwards
5751 * Asymmetric node setups can result in situations where the domain tree is of
5752 * unequal depth, make sure to skip domains that already cover the entire
5755 * In that case build_sched_domains() will have terminated the iteration early
5756 * and our sibling sd spans will be empty. Domains should always include the
5757 * cpu they're built on, so check that.
5760 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
5762 const struct cpumask
*span
= sched_domain_span(sd
);
5763 struct sd_data
*sdd
= sd
->private;
5764 struct sched_domain
*sibling
;
5767 for_each_cpu(i
, span
) {
5768 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5769 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5772 cpumask_set_cpu(i
, sched_group_mask(sg
));
5777 * Return the canonical balance cpu for this group, this is the first cpu
5778 * of this group that's also in the iteration mask.
5780 int group_balance_cpu(struct sched_group
*sg
)
5782 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
5786 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
5788 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
5789 const struct cpumask
*span
= sched_domain_span(sd
);
5790 struct cpumask
*covered
= sched_domains_tmpmask
;
5791 struct sd_data
*sdd
= sd
->private;
5792 struct sched_domain
*child
;
5795 cpumask_clear(covered
);
5797 for_each_cpu(i
, span
) {
5798 struct cpumask
*sg_span
;
5800 if (cpumask_test_cpu(i
, covered
))
5803 child
= *per_cpu_ptr(sdd
->sd
, i
);
5805 /* See the comment near build_group_mask(). */
5806 if (!cpumask_test_cpu(i
, sched_domain_span(child
)))
5809 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5810 GFP_KERNEL
, cpu_to_node(cpu
));
5815 sg_span
= sched_group_cpus(sg
);
5817 child
= child
->child
;
5818 cpumask_copy(sg_span
, sched_domain_span(child
));
5820 cpumask_set_cpu(i
, sg_span
);
5822 cpumask_or(covered
, covered
, sg_span
);
5824 sg
->sgp
= *per_cpu_ptr(sdd
->sgp
, i
);
5825 if (atomic_inc_return(&sg
->sgp
->ref
) == 1)
5826 build_group_mask(sd
, sg
);
5829 * Initialize sgp->power such that even if we mess up the
5830 * domains and no possible iteration will get us here, we won't
5833 sg
->sgp
->power
= SCHED_POWER_SCALE
* cpumask_weight(sg_span
);
5836 * Make sure the first group of this domain contains the
5837 * canonical balance cpu. Otherwise the sched_domain iteration
5838 * breaks. See update_sg_lb_stats().
5840 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
5841 group_balance_cpu(sg
) == cpu
)
5851 sd
->groups
= groups
;
5856 free_sched_groups(first
, 0);
5861 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
5863 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
5864 struct sched_domain
*child
= sd
->child
;
5867 cpu
= cpumask_first(sched_domain_span(child
));
5870 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
5871 (*sg
)->sgp
= *per_cpu_ptr(sdd
->sgp
, cpu
);
5872 atomic_set(&(*sg
)->sgp
->ref
, 1); /* for claim_allocations */
5879 * build_sched_groups will build a circular linked list of the groups
5880 * covered by the given span, and will set each group's ->cpumask correctly,
5881 * and ->cpu_power to 0.
5883 * Assumes the sched_domain tree is fully constructed
5886 build_sched_groups(struct sched_domain
*sd
, int cpu
)
5888 struct sched_group
*first
= NULL
, *last
= NULL
;
5889 struct sd_data
*sdd
= sd
->private;
5890 const struct cpumask
*span
= sched_domain_span(sd
);
5891 struct cpumask
*covered
;
5894 get_group(cpu
, sdd
, &sd
->groups
);
5895 atomic_inc(&sd
->groups
->ref
);
5897 if (cpu
!= cpumask_first(sched_domain_span(sd
)))
5900 lockdep_assert_held(&sched_domains_mutex
);
5901 covered
= sched_domains_tmpmask
;
5903 cpumask_clear(covered
);
5905 for_each_cpu(i
, span
) {
5906 struct sched_group
*sg
;
5907 int group
= get_group(i
, sdd
, &sg
);
5910 if (cpumask_test_cpu(i
, covered
))
5913 cpumask_clear(sched_group_cpus(sg
));
5915 cpumask_setall(sched_group_mask(sg
));
5917 for_each_cpu(j
, span
) {
5918 if (get_group(j
, sdd
, NULL
) != group
)
5921 cpumask_set_cpu(j
, covered
);
5922 cpumask_set_cpu(j
, sched_group_cpus(sg
));
5937 * Initialize sched groups cpu_power.
5939 * cpu_power indicates the capacity of sched group, which is used while
5940 * distributing the load between different sched groups in a sched domain.
5941 * Typically cpu_power for all the groups in a sched domain will be same unless
5942 * there are asymmetries in the topology. If there are asymmetries, group
5943 * having more cpu_power will pickup more load compared to the group having
5946 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5948 struct sched_group
*sg
= sd
->groups
;
5950 WARN_ON(!sd
|| !sg
);
5953 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
5955 } while (sg
!= sd
->groups
);
5957 if (cpu
!= group_balance_cpu(sg
))
5960 update_group_power(sd
, cpu
);
5961 atomic_set(&sg
->sgp
->nr_busy_cpus
, sg
->group_weight
);
5964 int __weak
arch_sd_sibling_asym_packing(void)
5966 return 0*SD_ASYM_PACKING
;
5970 * Initializers for schedule domains
5971 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5974 #ifdef CONFIG_SCHED_DEBUG
5975 # define SD_INIT_NAME(sd, type) sd->name = #type
5977 # define SD_INIT_NAME(sd, type) do { } while (0)
5980 #define SD_INIT_FUNC(type) \
5981 static noinline struct sched_domain * \
5982 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \
5984 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \
5985 *sd = SD_##type##_INIT; \
5986 SD_INIT_NAME(sd, type); \
5987 sd->private = &tl->data; \
5992 #ifdef CONFIG_SCHED_SMT
5993 SD_INIT_FUNC(SIBLING
)
5995 #ifdef CONFIG_SCHED_MC
5998 #ifdef CONFIG_SCHED_BOOK
6002 static int default_relax_domain_level
= -1;
6003 int sched_domain_level_max
;
6005 static int __init
setup_relax_domain_level(char *str
)
6007 if (kstrtoint(str
, 0, &default_relax_domain_level
))
6008 pr_warn("Unable to set relax_domain_level\n");
6012 __setup("relax_domain_level=", setup_relax_domain_level
);
6014 static void set_domain_attribute(struct sched_domain
*sd
,
6015 struct sched_domain_attr
*attr
)
6019 if (!attr
|| attr
->relax_domain_level
< 0) {
6020 if (default_relax_domain_level
< 0)
6023 request
= default_relax_domain_level
;
6025 request
= attr
->relax_domain_level
;
6026 if (request
< sd
->level
) {
6027 /* turn off idle balance on this domain */
6028 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6030 /* turn on idle balance on this domain */
6031 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6035 static void __sdt_free(const struct cpumask
*cpu_map
);
6036 static int __sdt_alloc(const struct cpumask
*cpu_map
);
6038 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
6039 const struct cpumask
*cpu_map
)
6043 if (!atomic_read(&d
->rd
->refcount
))
6044 free_rootdomain(&d
->rd
->rcu
); /* fall through */
6046 free_percpu(d
->sd
); /* fall through */
6048 __sdt_free(cpu_map
); /* fall through */
6054 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
6055 const struct cpumask
*cpu_map
)
6057 memset(d
, 0, sizeof(*d
));
6059 if (__sdt_alloc(cpu_map
))
6060 return sa_sd_storage
;
6061 d
->sd
= alloc_percpu(struct sched_domain
*);
6063 return sa_sd_storage
;
6064 d
->rd
= alloc_rootdomain();
6067 return sa_rootdomain
;
6071 * NULL the sd_data elements we've used to build the sched_domain and
6072 * sched_group structure so that the subsequent __free_domain_allocs()
6073 * will not free the data we're using.
6075 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6077 struct sd_data
*sdd
= sd
->private;
6079 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6080 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6082 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6083 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6085 if (atomic_read(&(*per_cpu_ptr(sdd
->sgp
, cpu
))->ref
))
6086 *per_cpu_ptr(sdd
->sgp
, cpu
) = NULL
;
6089 #ifdef CONFIG_SCHED_SMT
6090 static const struct cpumask
*cpu_smt_mask(int cpu
)
6092 return topology_thread_cpumask(cpu
);
6097 * Topology list, bottom-up.
6099 static struct sched_domain_topology_level default_topology
[] = {
6100 #ifdef CONFIG_SCHED_SMT
6101 { sd_init_SIBLING
, cpu_smt_mask
, },
6103 #ifdef CONFIG_SCHED_MC
6104 { sd_init_MC
, cpu_coregroup_mask
, },
6106 #ifdef CONFIG_SCHED_BOOK
6107 { sd_init_BOOK
, cpu_book_mask
, },
6109 { sd_init_CPU
, cpu_cpu_mask
, },
6113 static struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
6117 static int sched_domains_numa_levels
;
6118 static int *sched_domains_numa_distance
;
6119 static struct cpumask
***sched_domains_numa_masks
;
6120 static int sched_domains_curr_level
;
6122 static inline int sd_local_flags(int level
)
6124 if (sched_domains_numa_distance
[level
] > RECLAIM_DISTANCE
)
6127 return SD_BALANCE_EXEC
| SD_BALANCE_FORK
| SD_WAKE_AFFINE
;
6130 static struct sched_domain
*
6131 sd_numa_init(struct sched_domain_topology_level
*tl
, int cpu
)
6133 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6134 int level
= tl
->numa_level
;
6135 int sd_weight
= cpumask_weight(
6136 sched_domains_numa_masks
[level
][cpu_to_node(cpu
)]);
6138 *sd
= (struct sched_domain
){
6139 .min_interval
= sd_weight
,
6140 .max_interval
= 2*sd_weight
,
6142 .imbalance_pct
= 125,
6143 .cache_nice_tries
= 2,
6150 .flags
= 1*SD_LOAD_BALANCE
6151 | 1*SD_BALANCE_NEWIDLE
6156 | 0*SD_SHARE_CPUPOWER
6157 | 0*SD_SHARE_PKG_RESOURCES
6159 | 0*SD_PREFER_SIBLING
6160 | sd_local_flags(level
)
6162 .last_balance
= jiffies
,
6163 .balance_interval
= sd_weight
,
6165 SD_INIT_NAME(sd
, NUMA
);
6166 sd
->private = &tl
->data
;
6169 * Ugly hack to pass state to sd_numa_mask()...
6171 sched_domains_curr_level
= tl
->numa_level
;
6176 static const struct cpumask
*sd_numa_mask(int cpu
)
6178 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6181 static void sched_numa_warn(const char *str
)
6183 static int done
= false;
6191 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6193 for (i
= 0; i
< nr_node_ids
; i
++) {
6194 printk(KERN_WARNING
" ");
6195 for (j
= 0; j
< nr_node_ids
; j
++)
6196 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6197 printk(KERN_CONT
"\n");
6199 printk(KERN_WARNING
"\n");
6202 static bool find_numa_distance(int distance
)
6206 if (distance
== node_distance(0, 0))
6209 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6210 if (sched_domains_numa_distance
[i
] == distance
)
6217 static void sched_init_numa(void)
6219 int next_distance
, curr_distance
= node_distance(0, 0);
6220 struct sched_domain_topology_level
*tl
;
6224 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6225 if (!sched_domains_numa_distance
)
6229 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6230 * unique distances in the node_distance() table.
6232 * Assumes node_distance(0,j) includes all distances in
6233 * node_distance(i,j) in order to avoid cubic time.
6235 next_distance
= curr_distance
;
6236 for (i
= 0; i
< nr_node_ids
; i
++) {
6237 for (j
= 0; j
< nr_node_ids
; j
++) {
6238 for (k
= 0; k
< nr_node_ids
; k
++) {
6239 int distance
= node_distance(i
, k
);
6241 if (distance
> curr_distance
&&
6242 (distance
< next_distance
||
6243 next_distance
== curr_distance
))
6244 next_distance
= distance
;
6247 * While not a strong assumption it would be nice to know
6248 * about cases where if node A is connected to B, B is not
6249 * equally connected to A.
6251 if (sched_debug() && node_distance(k
, i
) != distance
)
6252 sched_numa_warn("Node-distance not symmetric");
6254 if (sched_debug() && i
&& !find_numa_distance(distance
))
6255 sched_numa_warn("Node-0 not representative");
6257 if (next_distance
!= curr_distance
) {
6258 sched_domains_numa_distance
[level
++] = next_distance
;
6259 sched_domains_numa_levels
= level
;
6260 curr_distance
= next_distance
;
6265 * In case of sched_debug() we verify the above assumption.
6271 * 'level' contains the number of unique distances, excluding the
6272 * identity distance node_distance(i,i).
6274 * The sched_domains_numa_distance[] array includes the actual distance
6279 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6280 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6281 * the array will contain less then 'level' members. This could be
6282 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6283 * in other functions.
6285 * We reset it to 'level' at the end of this function.
6287 sched_domains_numa_levels
= 0;
6289 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6290 if (!sched_domains_numa_masks
)
6294 * Now for each level, construct a mask per node which contains all
6295 * cpus of nodes that are that many hops away from us.
6297 for (i
= 0; i
< level
; i
++) {
6298 sched_domains_numa_masks
[i
] =
6299 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6300 if (!sched_domains_numa_masks
[i
])
6303 for (j
= 0; j
< nr_node_ids
; j
++) {
6304 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6308 sched_domains_numa_masks
[i
][j
] = mask
;
6310 for (k
= 0; k
< nr_node_ids
; k
++) {
6311 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6314 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6319 tl
= kzalloc((ARRAY_SIZE(default_topology
) + level
) *
6320 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6325 * Copy the default topology bits..
6327 for (i
= 0; default_topology
[i
].init
; i
++)
6328 tl
[i
] = default_topology
[i
];
6331 * .. and append 'j' levels of NUMA goodness.
6333 for (j
= 0; j
< level
; i
++, j
++) {
6334 tl
[i
] = (struct sched_domain_topology_level
){
6335 .init
= sd_numa_init
,
6336 .mask
= sd_numa_mask
,
6337 .flags
= SDTL_OVERLAP
,
6342 sched_domain_topology
= tl
;
6344 sched_domains_numa_levels
= level
;
6347 static void sched_domains_numa_masks_set(int cpu
)
6350 int node
= cpu_to_node(cpu
);
6352 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6353 for (j
= 0; j
< nr_node_ids
; j
++) {
6354 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6355 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6360 static void sched_domains_numa_masks_clear(int cpu
)
6363 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6364 for (j
= 0; j
< nr_node_ids
; j
++)
6365 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6370 * Update sched_domains_numa_masks[level][node] array when new cpus
6373 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6374 unsigned long action
,
6377 int cpu
= (long)hcpu
;
6379 switch (action
& ~CPU_TASKS_FROZEN
) {
6381 sched_domains_numa_masks_set(cpu
);
6385 sched_domains_numa_masks_clear(cpu
);
6395 static inline void sched_init_numa(void)
6399 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6400 unsigned long action
,
6405 #endif /* CONFIG_NUMA */
6407 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6409 struct sched_domain_topology_level
*tl
;
6412 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6413 struct sd_data
*sdd
= &tl
->data
;
6415 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6419 sdd
->sg
= alloc_percpu(struct sched_group
*);
6423 sdd
->sgp
= alloc_percpu(struct sched_group_power
*);
6427 for_each_cpu(j
, cpu_map
) {
6428 struct sched_domain
*sd
;
6429 struct sched_group
*sg
;
6430 struct sched_group_power
*sgp
;
6432 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6433 GFP_KERNEL
, cpu_to_node(j
));
6437 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6439 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6440 GFP_KERNEL
, cpu_to_node(j
));
6446 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6448 sgp
= kzalloc_node(sizeof(struct sched_group_power
) + cpumask_size(),
6449 GFP_KERNEL
, cpu_to_node(j
));
6453 *per_cpu_ptr(sdd
->sgp
, j
) = sgp
;
6460 static void __sdt_free(const struct cpumask
*cpu_map
)
6462 struct sched_domain_topology_level
*tl
;
6465 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6466 struct sd_data
*sdd
= &tl
->data
;
6468 for_each_cpu(j
, cpu_map
) {
6469 struct sched_domain
*sd
;
6472 sd
= *per_cpu_ptr(sdd
->sd
, j
);
6473 if (sd
&& (sd
->flags
& SD_OVERLAP
))
6474 free_sched_groups(sd
->groups
, 0);
6475 kfree(*per_cpu_ptr(sdd
->sd
, j
));
6479 kfree(*per_cpu_ptr(sdd
->sg
, j
));
6481 kfree(*per_cpu_ptr(sdd
->sgp
, j
));
6483 free_percpu(sdd
->sd
);
6485 free_percpu(sdd
->sg
);
6487 free_percpu(sdd
->sgp
);
6492 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
6493 struct s_data
*d
, const struct cpumask
*cpu_map
,
6494 struct sched_domain_attr
*attr
, struct sched_domain
*child
,
6497 struct sched_domain
*sd
= tl
->init(tl
, cpu
);
6501 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
6503 sd
->level
= child
->level
+ 1;
6504 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
6508 set_domain_attribute(sd
, attr
);
6514 * Build sched domains for a given set of cpus and attach the sched domains
6515 * to the individual cpus
6517 static int build_sched_domains(const struct cpumask
*cpu_map
,
6518 struct sched_domain_attr
*attr
)
6520 enum s_alloc alloc_state
= sa_none
;
6521 struct sched_domain
*sd
;
6523 int i
, ret
= -ENOMEM
;
6525 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
6526 if (alloc_state
!= sa_rootdomain
)
6529 /* Set up domains for cpus specified by the cpu_map. */
6530 for_each_cpu(i
, cpu_map
) {
6531 struct sched_domain_topology_level
*tl
;
6534 for (tl
= sched_domain_topology
; tl
->init
; tl
++) {
6535 sd
= build_sched_domain(tl
, &d
, cpu_map
, attr
, sd
, i
);
6536 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
6537 sd
->flags
|= SD_OVERLAP
;
6538 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
6545 *per_cpu_ptr(d
.sd
, i
) = sd
;
6548 /* Build the groups for the domains */
6549 for_each_cpu(i
, cpu_map
) {
6550 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6551 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
6552 if (sd
->flags
& SD_OVERLAP
) {
6553 if (build_overlap_sched_groups(sd
, i
))
6556 if (build_sched_groups(sd
, i
))
6562 /* Calculate CPU power for physical packages and nodes */
6563 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
6564 if (!cpumask_test_cpu(i
, cpu_map
))
6567 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6568 claim_allocations(i
, sd
);
6569 init_sched_groups_power(i
, sd
);
6573 /* Attach the domains */
6575 for_each_cpu(i
, cpu_map
) {
6576 sd
= *per_cpu_ptr(d
.sd
, i
);
6577 cpu_attach_domain(sd
, d
.rd
, i
);
6583 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
6587 static cpumask_var_t
*doms_cur
; /* current sched domains */
6588 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6589 static struct sched_domain_attr
*dattr_cur
;
6590 /* attribues of custom domains in 'doms_cur' */
6593 * Special case: If a kmalloc of a doms_cur partition (array of
6594 * cpumask) fails, then fallback to a single sched domain,
6595 * as determined by the single cpumask fallback_doms.
6597 static cpumask_var_t fallback_doms
;
6600 * arch_update_cpu_topology lets virtualized architectures update the
6601 * cpu core maps. It is supposed to return 1 if the topology changed
6602 * or 0 if it stayed the same.
6604 int __attribute__((weak
)) arch_update_cpu_topology(void)
6609 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
6612 cpumask_var_t
*doms
;
6614 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
6617 for (i
= 0; i
< ndoms
; i
++) {
6618 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
6619 free_sched_domains(doms
, i
);
6626 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
6629 for (i
= 0; i
< ndoms
; i
++)
6630 free_cpumask_var(doms
[i
]);
6635 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6636 * For now this just excludes isolated cpus, but could be used to
6637 * exclude other special cases in the future.
6639 static int init_sched_domains(const struct cpumask
*cpu_map
)
6643 arch_update_cpu_topology();
6645 doms_cur
= alloc_sched_domains(ndoms_cur
);
6647 doms_cur
= &fallback_doms
;
6648 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
6649 err
= build_sched_domains(doms_cur
[0], NULL
);
6650 register_sched_domain_sysctl();
6656 * Detach sched domains from a group of cpus specified in cpu_map
6657 * These cpus will now be attached to the NULL domain
6659 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
6664 for_each_cpu(i
, cpu_map
)
6665 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6669 /* handle null as "default" */
6670 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
6671 struct sched_domain_attr
*new, int idx_new
)
6673 struct sched_domain_attr tmp
;
6680 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
6681 new ? (new + idx_new
) : &tmp
,
6682 sizeof(struct sched_domain_attr
));
6686 * Partition sched domains as specified by the 'ndoms_new'
6687 * cpumasks in the array doms_new[] of cpumasks. This compares
6688 * doms_new[] to the current sched domain partitioning, doms_cur[].
6689 * It destroys each deleted domain and builds each new domain.
6691 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6692 * The masks don't intersect (don't overlap.) We should setup one
6693 * sched domain for each mask. CPUs not in any of the cpumasks will
6694 * not be load balanced. If the same cpumask appears both in the
6695 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6698 * The passed in 'doms_new' should be allocated using
6699 * alloc_sched_domains. This routine takes ownership of it and will
6700 * free_sched_domains it when done with it. If the caller failed the
6701 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6702 * and partition_sched_domains() will fallback to the single partition
6703 * 'fallback_doms', it also forces the domains to be rebuilt.
6705 * If doms_new == NULL it will be replaced with cpu_online_mask.
6706 * ndoms_new == 0 is a special case for destroying existing domains,
6707 * and it will not create the default domain.
6709 * Call with hotplug lock held
6711 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
6712 struct sched_domain_attr
*dattr_new
)
6717 mutex_lock(&sched_domains_mutex
);
6719 /* always unregister in case we don't destroy any domains */
6720 unregister_sched_domain_sysctl();
6722 /* Let architecture update cpu core mappings. */
6723 new_topology
= arch_update_cpu_topology();
6725 n
= doms_new
? ndoms_new
: 0;
6727 /* Destroy deleted domains */
6728 for (i
= 0; i
< ndoms_cur
; i
++) {
6729 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6730 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
6731 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
6734 /* no match - a current sched domain not in new doms_new[] */
6735 detach_destroy_domains(doms_cur
[i
]);
6740 if (doms_new
== NULL
) {
6742 doms_new
= &fallback_doms
;
6743 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
6744 WARN_ON_ONCE(dattr_new
);
6747 /* Build new domains */
6748 for (i
= 0; i
< ndoms_new
; i
++) {
6749 for (j
= 0; j
< ndoms_cur
&& !new_topology
; j
++) {
6750 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
6751 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
6754 /* no match - add a new doms_new */
6755 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
6760 /* Remember the new sched domains */
6761 if (doms_cur
!= &fallback_doms
)
6762 free_sched_domains(doms_cur
, ndoms_cur
);
6763 kfree(dattr_cur
); /* kfree(NULL) is safe */
6764 doms_cur
= doms_new
;
6765 dattr_cur
= dattr_new
;
6766 ndoms_cur
= ndoms_new
;
6768 register_sched_domain_sysctl();
6770 mutex_unlock(&sched_domains_mutex
);
6773 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
6776 * Update cpusets according to cpu_active mask. If cpusets are
6777 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6778 * around partition_sched_domains().
6780 * If we come here as part of a suspend/resume, don't touch cpusets because we
6781 * want to restore it back to its original state upon resume anyway.
6783 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
6787 case CPU_ONLINE_FROZEN
:
6788 case CPU_DOWN_FAILED_FROZEN
:
6791 * num_cpus_frozen tracks how many CPUs are involved in suspend
6792 * resume sequence. As long as this is not the last online
6793 * operation in the resume sequence, just build a single sched
6794 * domain, ignoring cpusets.
6797 if (likely(num_cpus_frozen
)) {
6798 partition_sched_domains(1, NULL
, NULL
);
6803 * This is the last CPU online operation. So fall through and
6804 * restore the original sched domains by considering the
6805 * cpuset configurations.
6809 case CPU_DOWN_FAILED
:
6810 cpuset_update_active_cpus(true);
6818 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
6822 case CPU_DOWN_PREPARE
:
6823 cpuset_update_active_cpus(false);
6825 case CPU_DOWN_PREPARE_FROZEN
:
6827 partition_sched_domains(1, NULL
, NULL
);
6835 void __init
sched_init_smp(void)
6837 cpumask_var_t non_isolated_cpus
;
6839 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
6840 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
6845 mutex_lock(&sched_domains_mutex
);
6846 init_sched_domains(cpu_active_mask
);
6847 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
6848 if (cpumask_empty(non_isolated_cpus
))
6849 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
6850 mutex_unlock(&sched_domains_mutex
);
6853 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
6854 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
6855 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
6857 /* RT runtime code needs to handle some hotplug events */
6858 hotcpu_notifier(update_runtime
, 0);
6862 /* Move init over to a non-isolated CPU */
6863 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
6865 sched_init_granularity();
6866 free_cpumask_var(non_isolated_cpus
);
6868 init_sched_rt_class();
6871 void __init
sched_init_smp(void)
6873 sched_init_granularity();
6875 #endif /* CONFIG_SMP */
6877 const_debug
unsigned int sysctl_timer_migration
= 1;
6879 int in_sched_functions(unsigned long addr
)
6881 return in_lock_functions(addr
) ||
6882 (addr
>= (unsigned long)__sched_text_start
6883 && addr
< (unsigned long)__sched_text_end
);
6886 #ifdef CONFIG_CGROUP_SCHED
6888 * Default task group.
6889 * Every task in system belongs to this group at bootup.
6891 struct task_group root_task_group
;
6892 LIST_HEAD(task_groups
);
6895 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
6897 void __init
sched_init(void)
6900 unsigned long alloc_size
= 0, ptr
;
6902 #ifdef CONFIG_FAIR_GROUP_SCHED
6903 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6905 #ifdef CONFIG_RT_GROUP_SCHED
6906 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
6908 #ifdef CONFIG_CPUMASK_OFFSTACK
6909 alloc_size
+= num_possible_cpus() * cpumask_size();
6912 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
6914 #ifdef CONFIG_FAIR_GROUP_SCHED
6915 root_task_group
.se
= (struct sched_entity
**)ptr
;
6916 ptr
+= nr_cpu_ids
* sizeof(void **);
6918 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
6919 ptr
+= nr_cpu_ids
* sizeof(void **);
6921 #endif /* CONFIG_FAIR_GROUP_SCHED */
6922 #ifdef CONFIG_RT_GROUP_SCHED
6923 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
6924 ptr
+= nr_cpu_ids
* sizeof(void **);
6926 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
6927 ptr
+= nr_cpu_ids
* sizeof(void **);
6929 #endif /* CONFIG_RT_GROUP_SCHED */
6930 #ifdef CONFIG_CPUMASK_OFFSTACK
6931 for_each_possible_cpu(i
) {
6932 per_cpu(load_balance_mask
, i
) = (void *)ptr
;
6933 ptr
+= cpumask_size();
6935 #endif /* CONFIG_CPUMASK_OFFSTACK */
6939 init_defrootdomain();
6942 init_rt_bandwidth(&def_rt_bandwidth
,
6943 global_rt_period(), global_rt_runtime());
6945 #ifdef CONFIG_RT_GROUP_SCHED
6946 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
6947 global_rt_period(), global_rt_runtime());
6948 #endif /* CONFIG_RT_GROUP_SCHED */
6950 #ifdef CONFIG_CGROUP_SCHED
6951 list_add(&root_task_group
.list
, &task_groups
);
6952 INIT_LIST_HEAD(&root_task_group
.children
);
6953 INIT_LIST_HEAD(&root_task_group
.siblings
);
6954 autogroup_init(&init_task
);
6956 #endif /* CONFIG_CGROUP_SCHED */
6958 for_each_possible_cpu(i
) {
6962 raw_spin_lock_init(&rq
->lock
);
6964 rq
->calc_load_active
= 0;
6965 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
6966 init_cfs_rq(&rq
->cfs
);
6967 init_rt_rq(&rq
->rt
, rq
);
6968 #ifdef CONFIG_FAIR_GROUP_SCHED
6969 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
6970 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6972 * How much cpu bandwidth does root_task_group get?
6974 * In case of task-groups formed thr' the cgroup filesystem, it
6975 * gets 100% of the cpu resources in the system. This overall
6976 * system cpu resource is divided among the tasks of
6977 * root_task_group and its child task-groups in a fair manner,
6978 * based on each entity's (task or task-group's) weight
6979 * (se->load.weight).
6981 * In other words, if root_task_group has 10 tasks of weight
6982 * 1024) and two child groups A0 and A1 (of weight 1024 each),
6983 * then A0's share of the cpu resource is:
6985 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
6987 * We achieve this by letting root_task_group's tasks sit
6988 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
6990 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
6991 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
6992 #endif /* CONFIG_FAIR_GROUP_SCHED */
6994 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
6995 #ifdef CONFIG_RT_GROUP_SCHED
6996 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
6997 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
7000 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7001 rq
->cpu_load
[j
] = 0;
7003 rq
->last_load_update_tick
= jiffies
;
7008 rq
->cpu_power
= SCHED_POWER_SCALE
;
7009 rq
->post_schedule
= 0;
7010 rq
->active_balance
= 0;
7011 rq
->next_balance
= jiffies
;
7016 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
7018 INIT_LIST_HEAD(&rq
->cfs_tasks
);
7020 rq_attach_root(rq
, &def_root_domain
);
7021 #ifdef CONFIG_NO_HZ_COMMON
7024 #ifdef CONFIG_NO_HZ_FULL
7025 rq
->last_sched_tick
= 0;
7029 atomic_set(&rq
->nr_iowait
, 0);
7032 set_load_weight(&init_task
);
7034 #ifdef CONFIG_PREEMPT_NOTIFIERS
7035 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7038 #ifdef CONFIG_RT_MUTEXES
7039 plist_head_init(&init_task
.pi_waiters
);
7043 * The boot idle thread does lazy MMU switching as well:
7045 atomic_inc(&init_mm
.mm_count
);
7046 enter_lazy_tlb(&init_mm
, current
);
7049 * Make us the idle thread. Technically, schedule() should not be
7050 * called from this thread, however somewhere below it might be,
7051 * but because we are the idle thread, we just pick up running again
7052 * when this runqueue becomes "idle".
7054 init_idle(current
, smp_processor_id());
7056 calc_load_update
= jiffies
+ LOAD_FREQ
;
7059 * During early bootup we pretend to be a normal task:
7061 current
->sched_class
= &fair_sched_class
;
7064 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
7065 /* May be allocated at isolcpus cmdline parse time */
7066 if (cpu_isolated_map
== NULL
)
7067 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
7068 idle_thread_set_boot_cpu();
7070 init_sched_fair_class();
7072 scheduler_running
= 1;
7075 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7076 static inline int preempt_count_equals(int preempt_offset
)
7078 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
7080 return (nested
== preempt_offset
);
7083 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7085 static unsigned long prev_jiffy
; /* ratelimiting */
7087 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7088 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled()) ||
7089 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7091 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7093 prev_jiffy
= jiffies
;
7096 "BUG: sleeping function called from invalid context at %s:%d\n",
7099 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7100 in_atomic(), irqs_disabled(),
7101 current
->pid
, current
->comm
);
7103 debug_show_held_locks(current
);
7104 if (irqs_disabled())
7105 print_irqtrace_events(current
);
7108 EXPORT_SYMBOL(__might_sleep
);
7111 #ifdef CONFIG_MAGIC_SYSRQ
7112 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7114 const struct sched_class
*prev_class
= p
->sched_class
;
7115 int old_prio
= p
->prio
;
7120 dequeue_task(rq
, p
, 0);
7121 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
7123 enqueue_task(rq
, p
, 0);
7124 resched_task(rq
->curr
);
7127 check_class_changed(rq
, p
, prev_class
, old_prio
);
7130 void normalize_rt_tasks(void)
7132 struct task_struct
*g
, *p
;
7133 unsigned long flags
;
7136 read_lock_irqsave(&tasklist_lock
, flags
);
7137 do_each_thread(g
, p
) {
7139 * Only normalize user tasks:
7144 p
->se
.exec_start
= 0;
7145 #ifdef CONFIG_SCHEDSTATS
7146 p
->se
.statistics
.wait_start
= 0;
7147 p
->se
.statistics
.sleep_start
= 0;
7148 p
->se
.statistics
.block_start
= 0;
7153 * Renice negative nice level userspace
7156 if (TASK_NICE(p
) < 0 && p
->mm
)
7157 set_user_nice(p
, 0);
7161 raw_spin_lock(&p
->pi_lock
);
7162 rq
= __task_rq_lock(p
);
7164 normalize_task(rq
, p
);
7166 __task_rq_unlock(rq
);
7167 raw_spin_unlock(&p
->pi_lock
);
7168 } while_each_thread(g
, p
);
7170 read_unlock_irqrestore(&tasklist_lock
, flags
);
7173 #endif /* CONFIG_MAGIC_SYSRQ */
7175 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7177 * These functions are only useful for the IA64 MCA handling, or kdb.
7179 * They can only be called when the whole system has been
7180 * stopped - every CPU needs to be quiescent, and no scheduling
7181 * activity can take place. Using them for anything else would
7182 * be a serious bug, and as a result, they aren't even visible
7183 * under any other configuration.
7187 * curr_task - return the current task for a given cpu.
7188 * @cpu: the processor in question.
7190 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7192 struct task_struct
*curr_task(int cpu
)
7194 return cpu_curr(cpu
);
7197 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7201 * set_curr_task - set the current task for a given cpu.
7202 * @cpu: the processor in question.
7203 * @p: the task pointer to set.
7205 * Description: This function must only be used when non-maskable interrupts
7206 * are serviced on a separate stack. It allows the architecture to switch the
7207 * notion of the current task on a cpu in a non-blocking manner. This function
7208 * must be called with all CPU's synchronized, and interrupts disabled, the
7209 * and caller must save the original value of the current task (see
7210 * curr_task() above) and restore that value before reenabling interrupts and
7211 * re-starting the system.
7213 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7215 void set_curr_task(int cpu
, struct task_struct
*p
)
7222 #ifdef CONFIG_CGROUP_SCHED
7223 /* task_group_lock serializes the addition/removal of task groups */
7224 static DEFINE_SPINLOCK(task_group_lock
);
7226 static void free_sched_group(struct task_group
*tg
)
7228 free_fair_sched_group(tg
);
7229 free_rt_sched_group(tg
);
7234 /* allocate runqueue etc for a new task group */
7235 struct task_group
*sched_create_group(struct task_group
*parent
)
7237 struct task_group
*tg
;
7239 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7241 return ERR_PTR(-ENOMEM
);
7243 if (!alloc_fair_sched_group(tg
, parent
))
7246 if (!alloc_rt_sched_group(tg
, parent
))
7252 free_sched_group(tg
);
7253 return ERR_PTR(-ENOMEM
);
7256 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7258 unsigned long flags
;
7260 spin_lock_irqsave(&task_group_lock
, flags
);
7261 list_add_rcu(&tg
->list
, &task_groups
);
7263 WARN_ON(!parent
); /* root should already exist */
7265 tg
->parent
= parent
;
7266 INIT_LIST_HEAD(&tg
->children
);
7267 list_add_rcu(&tg
->siblings
, &parent
->children
);
7268 spin_unlock_irqrestore(&task_group_lock
, flags
);
7271 /* rcu callback to free various structures associated with a task group */
7272 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7274 /* now it should be safe to free those cfs_rqs */
7275 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7278 /* Destroy runqueue etc associated with a task group */
7279 void sched_destroy_group(struct task_group
*tg
)
7281 /* wait for possible concurrent references to cfs_rqs complete */
7282 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7285 void sched_offline_group(struct task_group
*tg
)
7287 unsigned long flags
;
7290 /* end participation in shares distribution */
7291 for_each_possible_cpu(i
)
7292 unregister_fair_sched_group(tg
, i
);
7294 spin_lock_irqsave(&task_group_lock
, flags
);
7295 list_del_rcu(&tg
->list
);
7296 list_del_rcu(&tg
->siblings
);
7297 spin_unlock_irqrestore(&task_group_lock
, flags
);
7300 /* change task's runqueue when it moves between groups.
7301 * The caller of this function should have put the task in its new group
7302 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7303 * reflect its new group.
7305 void sched_move_task(struct task_struct
*tsk
)
7307 struct task_group
*tg
;
7309 unsigned long flags
;
7312 rq
= task_rq_lock(tsk
, &flags
);
7314 running
= task_current(rq
, tsk
);
7318 dequeue_task(rq
, tsk
, 0);
7319 if (unlikely(running
))
7320 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7322 tg
= container_of(task_subsys_state_check(tsk
, cpu_cgroup_subsys_id
,
7323 lockdep_is_held(&tsk
->sighand
->siglock
)),
7324 struct task_group
, css
);
7325 tg
= autogroup_task_group(tsk
, tg
);
7326 tsk
->sched_task_group
= tg
;
7328 #ifdef CONFIG_FAIR_GROUP_SCHED
7329 if (tsk
->sched_class
->task_move_group
)
7330 tsk
->sched_class
->task_move_group(tsk
, on_rq
);
7333 set_task_rq(tsk
, task_cpu(tsk
));
7335 if (unlikely(running
))
7336 tsk
->sched_class
->set_curr_task(rq
);
7338 enqueue_task(rq
, tsk
, 0);
7340 task_rq_unlock(rq
, tsk
, &flags
);
7342 #endif /* CONFIG_CGROUP_SCHED */
7344 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH)
7345 static unsigned long to_ratio(u64 period
, u64 runtime
)
7347 if (runtime
== RUNTIME_INF
)
7350 return div64_u64(runtime
<< 20, period
);
7354 #ifdef CONFIG_RT_GROUP_SCHED
7356 * Ensure that the real time constraints are schedulable.
7358 static DEFINE_MUTEX(rt_constraints_mutex
);
7360 /* Must be called with tasklist_lock held */
7361 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7363 struct task_struct
*g
, *p
;
7365 do_each_thread(g
, p
) {
7366 if (rt_task(p
) && task_rq(p
)->rt
.tg
== tg
)
7368 } while_each_thread(g
, p
);
7373 struct rt_schedulable_data
{
7374 struct task_group
*tg
;
7379 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7381 struct rt_schedulable_data
*d
= data
;
7382 struct task_group
*child
;
7383 unsigned long total
, sum
= 0;
7384 u64 period
, runtime
;
7386 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7387 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7390 period
= d
->rt_period
;
7391 runtime
= d
->rt_runtime
;
7395 * Cannot have more runtime than the period.
7397 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7401 * Ensure we don't starve existing RT tasks.
7403 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7406 total
= to_ratio(period
, runtime
);
7409 * Nobody can have more than the global setting allows.
7411 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7415 * The sum of our children's runtime should not exceed our own.
7417 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7418 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7419 runtime
= child
->rt_bandwidth
.rt_runtime
;
7421 if (child
== d
->tg
) {
7422 period
= d
->rt_period
;
7423 runtime
= d
->rt_runtime
;
7426 sum
+= to_ratio(period
, runtime
);
7435 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7439 struct rt_schedulable_data data
= {
7441 .rt_period
= period
,
7442 .rt_runtime
= runtime
,
7446 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
7452 static int tg_set_rt_bandwidth(struct task_group
*tg
,
7453 u64 rt_period
, u64 rt_runtime
)
7457 mutex_lock(&rt_constraints_mutex
);
7458 read_lock(&tasklist_lock
);
7459 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
7463 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7464 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
7465 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
7467 for_each_possible_cpu(i
) {
7468 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
7470 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7471 rt_rq
->rt_runtime
= rt_runtime
;
7472 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7474 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7476 read_unlock(&tasklist_lock
);
7477 mutex_unlock(&rt_constraints_mutex
);
7482 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7484 u64 rt_runtime
, rt_period
;
7486 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7487 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7488 if (rt_runtime_us
< 0)
7489 rt_runtime
= RUNTIME_INF
;
7491 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7494 static long sched_group_rt_runtime(struct task_group
*tg
)
7498 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
7501 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
7502 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7503 return rt_runtime_us
;
7506 static int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
7508 u64 rt_runtime
, rt_period
;
7510 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
7511 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
7516 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7519 static long sched_group_rt_period(struct task_group
*tg
)
7523 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7524 do_div(rt_period_us
, NSEC_PER_USEC
);
7525 return rt_period_us
;
7528 static int sched_rt_global_constraints(void)
7530 u64 runtime
, period
;
7533 if (sysctl_sched_rt_period
<= 0)
7536 runtime
= global_rt_runtime();
7537 period
= global_rt_period();
7540 * Sanity check on the sysctl variables.
7542 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7545 mutex_lock(&rt_constraints_mutex
);
7546 read_lock(&tasklist_lock
);
7547 ret
= __rt_schedulable(NULL
, 0, 0);
7548 read_unlock(&tasklist_lock
);
7549 mutex_unlock(&rt_constraints_mutex
);
7554 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
7556 /* Don't accept realtime tasks when there is no way for them to run */
7557 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
7563 #else /* !CONFIG_RT_GROUP_SCHED */
7564 static int sched_rt_global_constraints(void)
7566 unsigned long flags
;
7569 if (sysctl_sched_rt_period
<= 0)
7573 * There's always some RT tasks in the root group
7574 * -- migration, kstopmachine etc..
7576 if (sysctl_sched_rt_runtime
== 0)
7579 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7580 for_each_possible_cpu(i
) {
7581 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
7583 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7584 rt_rq
->rt_runtime
= global_rt_runtime();
7585 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7587 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7591 #endif /* CONFIG_RT_GROUP_SCHED */
7593 int sched_rr_handler(struct ctl_table
*table
, int write
,
7594 void __user
*buffer
, size_t *lenp
,
7598 static DEFINE_MUTEX(mutex
);
7601 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7602 /* make sure that internally we keep jiffies */
7603 /* also, writing zero resets timeslice to default */
7604 if (!ret
&& write
) {
7605 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
7606 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
7608 mutex_unlock(&mutex
);
7612 int sched_rt_handler(struct ctl_table
*table
, int write
,
7613 void __user
*buffer
, size_t *lenp
,
7617 int old_period
, old_runtime
;
7618 static DEFINE_MUTEX(mutex
);
7621 old_period
= sysctl_sched_rt_period
;
7622 old_runtime
= sysctl_sched_rt_runtime
;
7624 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7626 if (!ret
&& write
) {
7627 ret
= sched_rt_global_constraints();
7629 sysctl_sched_rt_period
= old_period
;
7630 sysctl_sched_rt_runtime
= old_runtime
;
7632 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
7633 def_rt_bandwidth
.rt_period
=
7634 ns_to_ktime(global_rt_period());
7637 mutex_unlock(&mutex
);
7642 #ifdef CONFIG_CGROUP_SCHED
7644 /* return corresponding task_group object of a cgroup */
7645 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7647 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7648 struct task_group
, css
);
7651 static struct cgroup_subsys_state
*cpu_cgroup_css_alloc(struct cgroup
*cgrp
)
7653 struct task_group
*tg
, *parent
;
7655 if (!cgrp
->parent
) {
7656 /* This is early initialization for the top cgroup */
7657 return &root_task_group
.css
;
7660 parent
= cgroup_tg(cgrp
->parent
);
7661 tg
= sched_create_group(parent
);
7663 return ERR_PTR(-ENOMEM
);
7668 static int cpu_cgroup_css_online(struct cgroup
*cgrp
)
7670 struct task_group
*tg
= cgroup_tg(cgrp
);
7671 struct task_group
*parent
;
7676 parent
= cgroup_tg(cgrp
->parent
);
7677 sched_online_group(tg
, parent
);
7681 static void cpu_cgroup_css_free(struct cgroup
*cgrp
)
7683 struct task_group
*tg
= cgroup_tg(cgrp
);
7685 sched_destroy_group(tg
);
7688 static void cpu_cgroup_css_offline(struct cgroup
*cgrp
)
7690 struct task_group
*tg
= cgroup_tg(cgrp
);
7692 sched_offline_group(tg
);
7695 static int cpu_cgroup_can_attach(struct cgroup
*cgrp
,
7696 struct cgroup_taskset
*tset
)
7698 struct task_struct
*task
;
7700 cgroup_taskset_for_each(task
, cgrp
, tset
) {
7701 #ifdef CONFIG_RT_GROUP_SCHED
7702 if (!sched_rt_can_attach(cgroup_tg(cgrp
), task
))
7705 /* We don't support RT-tasks being in separate groups */
7706 if (task
->sched_class
!= &fair_sched_class
)
7713 static void cpu_cgroup_attach(struct cgroup
*cgrp
,
7714 struct cgroup_taskset
*tset
)
7716 struct task_struct
*task
;
7718 cgroup_taskset_for_each(task
, cgrp
, tset
)
7719 sched_move_task(task
);
7723 cpu_cgroup_exit(struct cgroup
*cgrp
, struct cgroup
*old_cgrp
,
7724 struct task_struct
*task
)
7727 * cgroup_exit() is called in the copy_process() failure path.
7728 * Ignore this case since the task hasn't ran yet, this avoids
7729 * trying to poke a half freed task state from generic code.
7731 if (!(task
->flags
& PF_EXITING
))
7734 sched_move_task(task
);
7737 #ifdef CONFIG_FAIR_GROUP_SCHED
7738 static int cpu_shares_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7741 return sched_group_set_shares(cgroup_tg(cgrp
), scale_load(shareval
));
7744 static u64
cpu_shares_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7746 struct task_group
*tg
= cgroup_tg(cgrp
);
7748 return (u64
) scale_load_down(tg
->shares
);
7751 #ifdef CONFIG_CFS_BANDWIDTH
7752 static DEFINE_MUTEX(cfs_constraints_mutex
);
7754 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
7755 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
7757 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
7759 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
7761 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
7762 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7764 if (tg
== &root_task_group
)
7768 * Ensure we have at some amount of bandwidth every period. This is
7769 * to prevent reaching a state of large arrears when throttled via
7770 * entity_tick() resulting in prolonged exit starvation.
7772 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
7776 * Likewise, bound things on the otherside by preventing insane quota
7777 * periods. This also allows us to normalize in computing quota
7780 if (period
> max_cfs_quota_period
)
7783 mutex_lock(&cfs_constraints_mutex
);
7784 ret
= __cfs_schedulable(tg
, period
, quota
);
7788 runtime_enabled
= quota
!= RUNTIME_INF
;
7789 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
7790 account_cfs_bandwidth_used(runtime_enabled
, runtime_was_enabled
);
7791 raw_spin_lock_irq(&cfs_b
->lock
);
7792 cfs_b
->period
= ns_to_ktime(period
);
7793 cfs_b
->quota
= quota
;
7795 __refill_cfs_bandwidth_runtime(cfs_b
);
7796 /* restart the period timer (if active) to handle new period expiry */
7797 if (runtime_enabled
&& cfs_b
->timer_active
) {
7798 /* force a reprogram */
7799 cfs_b
->timer_active
= 0;
7800 __start_cfs_bandwidth(cfs_b
);
7802 raw_spin_unlock_irq(&cfs_b
->lock
);
7804 for_each_possible_cpu(i
) {
7805 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
7806 struct rq
*rq
= cfs_rq
->rq
;
7808 raw_spin_lock_irq(&rq
->lock
);
7809 cfs_rq
->runtime_enabled
= runtime_enabled
;
7810 cfs_rq
->runtime_remaining
= 0;
7812 if (cfs_rq
->throttled
)
7813 unthrottle_cfs_rq(cfs_rq
);
7814 raw_spin_unlock_irq(&rq
->lock
);
7817 mutex_unlock(&cfs_constraints_mutex
);
7822 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
7826 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7827 if (cfs_quota_us
< 0)
7828 quota
= RUNTIME_INF
;
7830 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
7832 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7835 long tg_get_cfs_quota(struct task_group
*tg
)
7839 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
7842 quota_us
= tg
->cfs_bandwidth
.quota
;
7843 do_div(quota_us
, NSEC_PER_USEC
);
7848 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
7852 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
7853 quota
= tg
->cfs_bandwidth
.quota
;
7855 return tg_set_cfs_bandwidth(tg
, period
, quota
);
7858 long tg_get_cfs_period(struct task_group
*tg
)
7862 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
7863 do_div(cfs_period_us
, NSEC_PER_USEC
);
7865 return cfs_period_us
;
7868 static s64
cpu_cfs_quota_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
)
7870 return tg_get_cfs_quota(cgroup_tg(cgrp
));
7873 static int cpu_cfs_quota_write_s64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7876 return tg_set_cfs_quota(cgroup_tg(cgrp
), cfs_quota_us
);
7879 static u64
cpu_cfs_period_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
)
7881 return tg_get_cfs_period(cgroup_tg(cgrp
));
7884 static int cpu_cfs_period_write_u64(struct cgroup
*cgrp
, struct cftype
*cftype
,
7887 return tg_set_cfs_period(cgroup_tg(cgrp
), cfs_period_us
);
7890 struct cfs_schedulable_data
{
7891 struct task_group
*tg
;
7896 * normalize group quota/period to be quota/max_period
7897 * note: units are usecs
7899 static u64
normalize_cfs_quota(struct task_group
*tg
,
7900 struct cfs_schedulable_data
*d
)
7908 period
= tg_get_cfs_period(tg
);
7909 quota
= tg_get_cfs_quota(tg
);
7912 /* note: these should typically be equivalent */
7913 if (quota
== RUNTIME_INF
|| quota
== -1)
7916 return to_ratio(period
, quota
);
7919 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
7921 struct cfs_schedulable_data
*d
= data
;
7922 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7923 s64 quota
= 0, parent_quota
= -1;
7926 quota
= RUNTIME_INF
;
7928 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
7930 quota
= normalize_cfs_quota(tg
, d
);
7931 parent_quota
= parent_b
->hierarchal_quota
;
7934 * ensure max(child_quota) <= parent_quota, inherit when no
7937 if (quota
== RUNTIME_INF
)
7938 quota
= parent_quota
;
7939 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
7942 cfs_b
->hierarchal_quota
= quota
;
7947 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
7950 struct cfs_schedulable_data data
= {
7956 if (quota
!= RUNTIME_INF
) {
7957 do_div(data
.period
, NSEC_PER_USEC
);
7958 do_div(data
.quota
, NSEC_PER_USEC
);
7962 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
7968 static int cpu_stats_show(struct cgroup
*cgrp
, struct cftype
*cft
,
7969 struct cgroup_map_cb
*cb
)
7971 struct task_group
*tg
= cgroup_tg(cgrp
);
7972 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
7974 cb
->fill(cb
, "nr_periods", cfs_b
->nr_periods
);
7975 cb
->fill(cb
, "nr_throttled", cfs_b
->nr_throttled
);
7976 cb
->fill(cb
, "throttled_time", cfs_b
->throttled_time
);
7980 #endif /* CONFIG_CFS_BANDWIDTH */
7981 #endif /* CONFIG_FAIR_GROUP_SCHED */
7983 #ifdef CONFIG_RT_GROUP_SCHED
7984 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
7987 return sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
7990 static s64
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
)
7992 return sched_group_rt_runtime(cgroup_tg(cgrp
));
7995 static int cpu_rt_period_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
7998 return sched_group_set_rt_period(cgroup_tg(cgrp
), rt_period_us
);
8001 static u64
cpu_rt_period_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
8003 return sched_group_rt_period(cgroup_tg(cgrp
));
8005 #endif /* CONFIG_RT_GROUP_SCHED */
8007 static struct cftype cpu_files
[] = {
8008 #ifdef CONFIG_FAIR_GROUP_SCHED
8011 .read_u64
= cpu_shares_read_u64
,
8012 .write_u64
= cpu_shares_write_u64
,
8015 #ifdef CONFIG_CFS_BANDWIDTH
8017 .name
= "cfs_quota_us",
8018 .read_s64
= cpu_cfs_quota_read_s64
,
8019 .write_s64
= cpu_cfs_quota_write_s64
,
8022 .name
= "cfs_period_us",
8023 .read_u64
= cpu_cfs_period_read_u64
,
8024 .write_u64
= cpu_cfs_period_write_u64
,
8028 .read_map
= cpu_stats_show
,
8031 #ifdef CONFIG_RT_GROUP_SCHED
8033 .name
= "rt_runtime_us",
8034 .read_s64
= cpu_rt_runtime_read
,
8035 .write_s64
= cpu_rt_runtime_write
,
8038 .name
= "rt_period_us",
8039 .read_u64
= cpu_rt_period_read_uint
,
8040 .write_u64
= cpu_rt_period_write_uint
,
8046 struct cgroup_subsys cpu_cgroup_subsys
= {
8048 .css_alloc
= cpu_cgroup_css_alloc
,
8049 .css_free
= cpu_cgroup_css_free
,
8050 .css_online
= cpu_cgroup_css_online
,
8051 .css_offline
= cpu_cgroup_css_offline
,
8052 .can_attach
= cpu_cgroup_can_attach
,
8053 .attach
= cpu_cgroup_attach
,
8054 .exit
= cpu_cgroup_exit
,
8055 .subsys_id
= cpu_cgroup_subsys_id
,
8056 .base_cftypes
= cpu_files
,
8060 #endif /* CONFIG_CGROUP_SCHED */
8062 void dump_cpu_task(int cpu
)
8064 pr_info("Task dump for CPU %d:\n", cpu
);
8065 sched_show_task(cpu_curr(cpu
));