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>
76 #include <linux/compiler.h>
78 #include <asm/switch_to.h>
80 #include <asm/irq_regs.h>
81 #include <asm/mutex.h>
82 #ifdef CONFIG_PARAVIRT
83 #include <asm/paravirt.h>
87 #include "../workqueue_internal.h"
88 #include "../smpboot.h"
90 #define CREATE_TRACE_POINTS
91 #include <trace/events/sched.h>
93 void start_bandwidth_timer(struct hrtimer
*period_timer
, ktime_t period
)
96 ktime_t soft
, hard
, now
;
99 if (hrtimer_active(period_timer
))
102 now
= hrtimer_cb_get_time(period_timer
);
103 hrtimer_forward(period_timer
, now
, period
);
105 soft
= hrtimer_get_softexpires(period_timer
);
106 hard
= hrtimer_get_expires(period_timer
);
107 delta
= ktime_to_ns(ktime_sub(hard
, soft
));
108 __hrtimer_start_range_ns(period_timer
, soft
, delta
,
109 HRTIMER_MODE_ABS_PINNED
, 0);
113 DEFINE_MUTEX(sched_domains_mutex
);
114 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
116 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
118 void update_rq_clock(struct rq
*rq
)
122 lockdep_assert_held(&rq
->lock
);
124 if (rq
->clock_skip_update
& RQCF_ACT_SKIP
)
127 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
131 update_rq_clock_task(rq
, delta
);
135 * Debugging: various feature bits
138 #define SCHED_FEAT(name, enabled) \
139 (1UL << __SCHED_FEAT_##name) * enabled |
141 const_debug
unsigned int sysctl_sched_features
=
142 #include "features.h"
147 #ifdef CONFIG_SCHED_DEBUG
148 #define SCHED_FEAT(name, enabled) \
151 static const char * const sched_feat_names
[] = {
152 #include "features.h"
157 static int sched_feat_show(struct seq_file
*m
, void *v
)
161 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
162 if (!(sysctl_sched_features
& (1UL << i
)))
164 seq_printf(m
, "%s ", sched_feat_names
[i
]);
171 #ifdef HAVE_JUMP_LABEL
173 #define jump_label_key__true STATIC_KEY_INIT_TRUE
174 #define jump_label_key__false STATIC_KEY_INIT_FALSE
176 #define SCHED_FEAT(name, enabled) \
177 jump_label_key__##enabled ,
179 struct static_key sched_feat_keys
[__SCHED_FEAT_NR
] = {
180 #include "features.h"
185 static void sched_feat_disable(int i
)
187 if (static_key_enabled(&sched_feat_keys
[i
]))
188 static_key_slow_dec(&sched_feat_keys
[i
]);
191 static void sched_feat_enable(int i
)
193 if (!static_key_enabled(&sched_feat_keys
[i
]))
194 static_key_slow_inc(&sched_feat_keys
[i
]);
197 static void sched_feat_disable(int i
) { };
198 static void sched_feat_enable(int i
) { };
199 #endif /* HAVE_JUMP_LABEL */
201 static int sched_feat_set(char *cmp
)
206 if (strncmp(cmp
, "NO_", 3) == 0) {
211 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
212 if (strcmp(cmp
, sched_feat_names
[i
]) == 0) {
214 sysctl_sched_features
&= ~(1UL << i
);
215 sched_feat_disable(i
);
217 sysctl_sched_features
|= (1UL << i
);
218 sched_feat_enable(i
);
228 sched_feat_write(struct file
*filp
, const char __user
*ubuf
,
229 size_t cnt
, loff_t
*ppos
)
239 if (copy_from_user(&buf
, ubuf
, cnt
))
245 /* Ensure the static_key remains in a consistent state */
246 inode
= file_inode(filp
);
247 mutex_lock(&inode
->i_mutex
);
248 i
= sched_feat_set(cmp
);
249 mutex_unlock(&inode
->i_mutex
);
250 if (i
== __SCHED_FEAT_NR
)
258 static int sched_feat_open(struct inode
*inode
, struct file
*filp
)
260 return single_open(filp
, sched_feat_show
, NULL
);
263 static const struct file_operations sched_feat_fops
= {
264 .open
= sched_feat_open
,
265 .write
= sched_feat_write
,
268 .release
= single_release
,
271 static __init
int sched_init_debug(void)
273 debugfs_create_file("sched_features", 0644, NULL
, NULL
,
278 late_initcall(sched_init_debug
);
279 #endif /* CONFIG_SCHED_DEBUG */
282 * Number of tasks to iterate in a single balance run.
283 * Limited because this is done with IRQs disabled.
285 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
288 * period over which we average the RT time consumption, measured
293 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
296 * period over which we measure -rt task cpu usage in us.
299 unsigned int sysctl_sched_rt_period
= 1000000;
301 __read_mostly
int scheduler_running
;
304 * part of the period that we allow rt tasks to run in us.
307 int sysctl_sched_rt_runtime
= 950000;
310 * this_rq_lock - lock this runqueue and disable interrupts.
312 static struct rq
*this_rq_lock(void)
319 raw_spin_lock(&rq
->lock
);
324 #ifdef CONFIG_SCHED_HRTICK
326 * Use HR-timers to deliver accurate preemption points.
329 static void hrtick_clear(struct rq
*rq
)
331 if (hrtimer_active(&rq
->hrtick_timer
))
332 hrtimer_cancel(&rq
->hrtick_timer
);
336 * High-resolution timer tick.
337 * Runs from hardirq context with interrupts disabled.
339 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
341 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
343 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
345 raw_spin_lock(&rq
->lock
);
347 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
348 raw_spin_unlock(&rq
->lock
);
350 return HRTIMER_NORESTART
;
355 static int __hrtick_restart(struct rq
*rq
)
357 struct hrtimer
*timer
= &rq
->hrtick_timer
;
358 ktime_t time
= hrtimer_get_softexpires(timer
);
360 return __hrtimer_start_range_ns(timer
, time
, 0, HRTIMER_MODE_ABS_PINNED
, 0);
364 * called from hardirq (IPI) context
366 static void __hrtick_start(void *arg
)
370 raw_spin_lock(&rq
->lock
);
371 __hrtick_restart(rq
);
372 rq
->hrtick_csd_pending
= 0;
373 raw_spin_unlock(&rq
->lock
);
377 * Called to set the hrtick timer state.
379 * called with rq->lock held and irqs disabled
381 void hrtick_start(struct rq
*rq
, u64 delay
)
383 struct hrtimer
*timer
= &rq
->hrtick_timer
;
388 * Don't schedule slices shorter than 10000ns, that just
389 * doesn't make sense and can cause timer DoS.
391 delta
= max_t(s64
, delay
, 10000LL);
392 time
= ktime_add_ns(timer
->base
->get_time(), delta
);
394 hrtimer_set_expires(timer
, time
);
396 if (rq
== this_rq()) {
397 __hrtick_restart(rq
);
398 } else if (!rq
->hrtick_csd_pending
) {
399 smp_call_function_single_async(cpu_of(rq
), &rq
->hrtick_csd
);
400 rq
->hrtick_csd_pending
= 1;
405 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
407 int cpu
= (int)(long)hcpu
;
410 case CPU_UP_CANCELED
:
411 case CPU_UP_CANCELED_FROZEN
:
412 case CPU_DOWN_PREPARE
:
413 case CPU_DOWN_PREPARE_FROZEN
:
415 case CPU_DEAD_FROZEN
:
416 hrtick_clear(cpu_rq(cpu
));
423 static __init
void init_hrtick(void)
425 hotcpu_notifier(hotplug_hrtick
, 0);
429 * Called to set the hrtick timer state.
431 * called with rq->lock held and irqs disabled
433 void hrtick_start(struct rq
*rq
, u64 delay
)
436 * Don't schedule slices shorter than 10000ns, that just
437 * doesn't make sense. Rely on vruntime for fairness.
439 delay
= max_t(u64
, delay
, 10000LL);
440 __hrtimer_start_range_ns(&rq
->hrtick_timer
, ns_to_ktime(delay
), 0,
441 HRTIMER_MODE_REL_PINNED
, 0);
444 static inline void init_hrtick(void)
447 #endif /* CONFIG_SMP */
449 static void init_rq_hrtick(struct rq
*rq
)
452 rq
->hrtick_csd_pending
= 0;
454 rq
->hrtick_csd
.flags
= 0;
455 rq
->hrtick_csd
.func
= __hrtick_start
;
456 rq
->hrtick_csd
.info
= rq
;
459 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
460 rq
->hrtick_timer
.function
= hrtick
;
462 #else /* CONFIG_SCHED_HRTICK */
463 static inline void hrtick_clear(struct rq
*rq
)
467 static inline void init_rq_hrtick(struct rq
*rq
)
471 static inline void init_hrtick(void)
474 #endif /* CONFIG_SCHED_HRTICK */
477 * cmpxchg based fetch_or, macro so it works for different integer types
479 #define fetch_or(ptr, val) \
480 ({ typeof(*(ptr)) __old, __val = *(ptr); \
482 __old = cmpxchg((ptr), __val, __val | (val)); \
483 if (__old == __val) \
490 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
492 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
493 * this avoids any races wrt polling state changes and thereby avoids
496 static bool set_nr_and_not_polling(struct task_struct
*p
)
498 struct thread_info
*ti
= task_thread_info(p
);
499 return !(fetch_or(&ti
->flags
, _TIF_NEED_RESCHED
) & _TIF_POLLING_NRFLAG
);
503 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
505 * If this returns true, then the idle task promises to call
506 * sched_ttwu_pending() and reschedule soon.
508 static bool set_nr_if_polling(struct task_struct
*p
)
510 struct thread_info
*ti
= task_thread_info(p
);
511 typeof(ti
->flags
) old
, val
= ACCESS_ONCE(ti
->flags
);
514 if (!(val
& _TIF_POLLING_NRFLAG
))
516 if (val
& _TIF_NEED_RESCHED
)
518 old
= cmpxchg(&ti
->flags
, val
, val
| _TIF_NEED_RESCHED
);
527 static bool set_nr_and_not_polling(struct task_struct
*p
)
529 set_tsk_need_resched(p
);
534 static bool set_nr_if_polling(struct task_struct
*p
)
542 * resched_curr - mark rq's current task 'to be rescheduled now'.
544 * On UP this means the setting of the need_resched flag, on SMP it
545 * might also involve a cross-CPU call to trigger the scheduler on
548 void resched_curr(struct rq
*rq
)
550 struct task_struct
*curr
= rq
->curr
;
553 lockdep_assert_held(&rq
->lock
);
555 if (test_tsk_need_resched(curr
))
560 if (cpu
== smp_processor_id()) {
561 set_tsk_need_resched(curr
);
562 set_preempt_need_resched();
566 if (set_nr_and_not_polling(curr
))
567 smp_send_reschedule(cpu
);
569 trace_sched_wake_idle_without_ipi(cpu
);
572 void resched_cpu(int cpu
)
574 struct rq
*rq
= cpu_rq(cpu
);
577 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
580 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
584 #ifdef CONFIG_NO_HZ_COMMON
586 * In the semi idle case, use the nearest busy cpu for migrating timers
587 * from an idle cpu. This is good for power-savings.
589 * We don't do similar optimization for completely idle system, as
590 * selecting an idle cpu will add more delays to the timers than intended
591 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
593 int get_nohz_timer_target(int pinned
)
595 int cpu
= smp_processor_id();
597 struct sched_domain
*sd
;
599 if (pinned
|| !get_sysctl_timer_migration() || !idle_cpu(cpu
))
603 for_each_domain(cpu
, sd
) {
604 for_each_cpu(i
, sched_domain_span(sd
)) {
616 * When add_timer_on() enqueues a timer into the timer wheel of an
617 * idle CPU then this timer might expire before the next timer event
618 * which is scheduled to wake up that CPU. In case of a completely
619 * idle system the next event might even be infinite time into the
620 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
621 * leaves the inner idle loop so the newly added timer is taken into
622 * account when the CPU goes back to idle and evaluates the timer
623 * wheel for the next timer event.
625 static void wake_up_idle_cpu(int cpu
)
627 struct rq
*rq
= cpu_rq(cpu
);
629 if (cpu
== smp_processor_id())
632 if (set_nr_and_not_polling(rq
->idle
))
633 smp_send_reschedule(cpu
);
635 trace_sched_wake_idle_without_ipi(cpu
);
638 static bool wake_up_full_nohz_cpu(int cpu
)
641 * We just need the target to call irq_exit() and re-evaluate
642 * the next tick. The nohz full kick at least implies that.
643 * If needed we can still optimize that later with an
646 if (tick_nohz_full_cpu(cpu
)) {
647 if (cpu
!= smp_processor_id() ||
648 tick_nohz_tick_stopped())
649 tick_nohz_full_kick_cpu(cpu
);
656 void wake_up_nohz_cpu(int cpu
)
658 if (!wake_up_full_nohz_cpu(cpu
))
659 wake_up_idle_cpu(cpu
);
662 static inline bool got_nohz_idle_kick(void)
664 int cpu
= smp_processor_id();
666 if (!test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
)))
669 if (idle_cpu(cpu
) && !need_resched())
673 * We can't run Idle Load Balance on this CPU for this time so we
674 * cancel it and clear NOHZ_BALANCE_KICK
676 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
680 #else /* CONFIG_NO_HZ_COMMON */
682 static inline bool got_nohz_idle_kick(void)
687 #endif /* CONFIG_NO_HZ_COMMON */
689 #ifdef CONFIG_NO_HZ_FULL
690 bool sched_can_stop_tick(void)
693 * More than one running task need preemption.
694 * nr_running update is assumed to be visible
695 * after IPI is sent from wakers.
697 if (this_rq()->nr_running
> 1)
702 #endif /* CONFIG_NO_HZ_FULL */
704 void sched_avg_update(struct rq
*rq
)
706 s64 period
= sched_avg_period();
708 while ((s64
)(rq_clock(rq
) - rq
->age_stamp
) > period
) {
710 * Inline assembly required to prevent the compiler
711 * optimising this loop into a divmod call.
712 * See __iter_div_u64_rem() for another example of this.
714 asm("" : "+rm" (rq
->age_stamp
));
715 rq
->age_stamp
+= period
;
720 #endif /* CONFIG_SMP */
722 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
723 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
725 * Iterate task_group tree rooted at *from, calling @down when first entering a
726 * node and @up when leaving it for the final time.
728 * Caller must hold rcu_lock or sufficient equivalent.
730 int walk_tg_tree_from(struct task_group
*from
,
731 tg_visitor down
, tg_visitor up
, void *data
)
733 struct task_group
*parent
, *child
;
739 ret
= (*down
)(parent
, data
);
742 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
749 ret
= (*up
)(parent
, data
);
750 if (ret
|| parent
== from
)
754 parent
= parent
->parent
;
761 int tg_nop(struct task_group
*tg
, void *data
)
767 static void set_load_weight(struct task_struct
*p
)
769 int prio
= p
->static_prio
- MAX_RT_PRIO
;
770 struct load_weight
*load
= &p
->se
.load
;
773 * SCHED_IDLE tasks get minimal weight:
775 if (p
->policy
== SCHED_IDLE
) {
776 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
777 load
->inv_weight
= WMULT_IDLEPRIO
;
781 load
->weight
= scale_load(prio_to_weight
[prio
]);
782 load
->inv_weight
= prio_to_wmult
[prio
];
785 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
788 sched_info_queued(rq
, p
);
789 p
->sched_class
->enqueue_task(rq
, p
, flags
);
792 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
795 sched_info_dequeued(rq
, p
);
796 p
->sched_class
->dequeue_task(rq
, p
, flags
);
799 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
801 if (task_contributes_to_load(p
))
802 rq
->nr_uninterruptible
--;
804 enqueue_task(rq
, p
, flags
);
807 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
809 if (task_contributes_to_load(p
))
810 rq
->nr_uninterruptible
++;
812 dequeue_task(rq
, p
, flags
);
815 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
818 * In theory, the compile should just see 0 here, and optimize out the call
819 * to sched_rt_avg_update. But I don't trust it...
821 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
822 s64 steal
= 0, irq_delta
= 0;
824 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
825 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
828 * Since irq_time is only updated on {soft,}irq_exit, we might run into
829 * this case when a previous update_rq_clock() happened inside a
832 * When this happens, we stop ->clock_task and only update the
833 * prev_irq_time stamp to account for the part that fit, so that a next
834 * update will consume the rest. This ensures ->clock_task is
837 * It does however cause some slight miss-attribution of {soft,}irq
838 * time, a more accurate solution would be to update the irq_time using
839 * the current rq->clock timestamp, except that would require using
842 if (irq_delta
> delta
)
845 rq
->prev_irq_time
+= irq_delta
;
848 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
849 if (static_key_false((¶virt_steal_rq_enabled
))) {
850 steal
= paravirt_steal_clock(cpu_of(rq
));
851 steal
-= rq
->prev_steal_time_rq
;
853 if (unlikely(steal
> delta
))
856 rq
->prev_steal_time_rq
+= steal
;
861 rq
->clock_task
+= delta
;
863 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
864 if ((irq_delta
+ steal
) && sched_feat(NONTASK_CAPACITY
))
865 sched_rt_avg_update(rq
, irq_delta
+ steal
);
869 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
871 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
872 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
876 * Make it appear like a SCHED_FIFO task, its something
877 * userspace knows about and won't get confused about.
879 * Also, it will make PI more or less work without too
880 * much confusion -- but then, stop work should not
881 * rely on PI working anyway.
883 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
885 stop
->sched_class
= &stop_sched_class
;
888 cpu_rq(cpu
)->stop
= stop
;
892 * Reset it back to a normal scheduling class so that
893 * it can die in pieces.
895 old_stop
->sched_class
= &rt_sched_class
;
900 * __normal_prio - return the priority that is based on the static prio
902 static inline int __normal_prio(struct task_struct
*p
)
904 return p
->static_prio
;
908 * Calculate the expected normal priority: i.e. priority
909 * without taking RT-inheritance into account. Might be
910 * boosted by interactivity modifiers. Changes upon fork,
911 * setprio syscalls, and whenever the interactivity
912 * estimator recalculates.
914 static inline int normal_prio(struct task_struct
*p
)
918 if (task_has_dl_policy(p
))
919 prio
= MAX_DL_PRIO
-1;
920 else if (task_has_rt_policy(p
))
921 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
923 prio
= __normal_prio(p
);
928 * Calculate the current priority, i.e. the priority
929 * taken into account by the scheduler. This value might
930 * be boosted by RT tasks, or might be boosted by
931 * interactivity modifiers. Will be RT if the task got
932 * RT-boosted. If not then it returns p->normal_prio.
934 static int effective_prio(struct task_struct
*p
)
936 p
->normal_prio
= normal_prio(p
);
938 * If we are RT tasks or we were boosted to RT priority,
939 * keep the priority unchanged. Otherwise, update priority
940 * to the normal priority:
942 if (!rt_prio(p
->prio
))
943 return p
->normal_prio
;
948 * task_curr - is this task currently executing on a CPU?
949 * @p: the task in question.
951 * Return: 1 if the task is currently executing. 0 otherwise.
953 inline int task_curr(const struct task_struct
*p
)
955 return cpu_curr(task_cpu(p
)) == p
;
959 * Can drop rq->lock because from sched_class::switched_from() methods drop it.
961 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
962 const struct sched_class
*prev_class
,
965 if (prev_class
!= p
->sched_class
) {
966 if (prev_class
->switched_from
)
967 prev_class
->switched_from(rq
, p
);
968 /* Possble rq->lock 'hole'. */
969 p
->sched_class
->switched_to(rq
, p
);
970 } else if (oldprio
!= p
->prio
|| dl_task(p
))
971 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
974 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
976 const struct sched_class
*class;
978 if (p
->sched_class
== rq
->curr
->sched_class
) {
979 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
981 for_each_class(class) {
982 if (class == rq
->curr
->sched_class
)
984 if (class == p
->sched_class
) {
992 * A queue event has occurred, and we're going to schedule. In
993 * this case, we can save a useless back to back clock update.
995 if (task_on_rq_queued(rq
->curr
) && test_tsk_need_resched(rq
->curr
))
996 rq_clock_skip_update(rq
, true);
1000 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1002 #ifdef CONFIG_SCHED_DEBUG
1004 * We should never call set_task_cpu() on a blocked task,
1005 * ttwu() will sort out the placement.
1007 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
1010 #ifdef CONFIG_LOCKDEP
1012 * The caller should hold either p->pi_lock or rq->lock, when changing
1013 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1015 * sched_move_task() holds both and thus holding either pins the cgroup,
1018 * Furthermore, all task_rq users should acquire both locks, see
1021 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
1022 lockdep_is_held(&task_rq(p
)->lock
)));
1026 trace_sched_migrate_task(p
, new_cpu
);
1028 if (task_cpu(p
) != new_cpu
) {
1029 if (p
->sched_class
->migrate_task_rq
)
1030 p
->sched_class
->migrate_task_rq(p
, new_cpu
);
1031 p
->se
.nr_migrations
++;
1032 perf_sw_event_sched(PERF_COUNT_SW_CPU_MIGRATIONS
, 1, 0);
1035 __set_task_cpu(p
, new_cpu
);
1038 static void __migrate_swap_task(struct task_struct
*p
, int cpu
)
1040 if (task_on_rq_queued(p
)) {
1041 struct rq
*src_rq
, *dst_rq
;
1043 src_rq
= task_rq(p
);
1044 dst_rq
= cpu_rq(cpu
);
1046 deactivate_task(src_rq
, p
, 0);
1047 set_task_cpu(p
, cpu
);
1048 activate_task(dst_rq
, p
, 0);
1049 check_preempt_curr(dst_rq
, p
, 0);
1052 * Task isn't running anymore; make it appear like we migrated
1053 * it before it went to sleep. This means on wakeup we make the
1054 * previous cpu our targer instead of where it really is.
1060 struct migration_swap_arg
{
1061 struct task_struct
*src_task
, *dst_task
;
1062 int src_cpu
, dst_cpu
;
1065 static int migrate_swap_stop(void *data
)
1067 struct migration_swap_arg
*arg
= data
;
1068 struct rq
*src_rq
, *dst_rq
;
1071 src_rq
= cpu_rq(arg
->src_cpu
);
1072 dst_rq
= cpu_rq(arg
->dst_cpu
);
1074 double_raw_lock(&arg
->src_task
->pi_lock
,
1075 &arg
->dst_task
->pi_lock
);
1076 double_rq_lock(src_rq
, dst_rq
);
1077 if (task_cpu(arg
->dst_task
) != arg
->dst_cpu
)
1080 if (task_cpu(arg
->src_task
) != arg
->src_cpu
)
1083 if (!cpumask_test_cpu(arg
->dst_cpu
, tsk_cpus_allowed(arg
->src_task
)))
1086 if (!cpumask_test_cpu(arg
->src_cpu
, tsk_cpus_allowed(arg
->dst_task
)))
1089 __migrate_swap_task(arg
->src_task
, arg
->dst_cpu
);
1090 __migrate_swap_task(arg
->dst_task
, arg
->src_cpu
);
1095 double_rq_unlock(src_rq
, dst_rq
);
1096 raw_spin_unlock(&arg
->dst_task
->pi_lock
);
1097 raw_spin_unlock(&arg
->src_task
->pi_lock
);
1103 * Cross migrate two tasks
1105 int migrate_swap(struct task_struct
*cur
, struct task_struct
*p
)
1107 struct migration_swap_arg arg
;
1110 arg
= (struct migration_swap_arg
){
1112 .src_cpu
= task_cpu(cur
),
1114 .dst_cpu
= task_cpu(p
),
1117 if (arg
.src_cpu
== arg
.dst_cpu
)
1121 * These three tests are all lockless; this is OK since all of them
1122 * will be re-checked with proper locks held further down the line.
1124 if (!cpu_active(arg
.src_cpu
) || !cpu_active(arg
.dst_cpu
))
1127 if (!cpumask_test_cpu(arg
.dst_cpu
, tsk_cpus_allowed(arg
.src_task
)))
1130 if (!cpumask_test_cpu(arg
.src_cpu
, tsk_cpus_allowed(arg
.dst_task
)))
1133 trace_sched_swap_numa(cur
, arg
.src_cpu
, p
, arg
.dst_cpu
);
1134 ret
= stop_two_cpus(arg
.dst_cpu
, arg
.src_cpu
, migrate_swap_stop
, &arg
);
1140 struct migration_arg
{
1141 struct task_struct
*task
;
1145 static int migration_cpu_stop(void *data
);
1148 * wait_task_inactive - wait for a thread to unschedule.
1150 * If @match_state is nonzero, it's the @p->state value just checked and
1151 * not expected to change. If it changes, i.e. @p might have woken up,
1152 * then return zero. When we succeed in waiting for @p to be off its CPU,
1153 * we return a positive number (its total switch count). If a second call
1154 * a short while later returns the same number, the caller can be sure that
1155 * @p has remained unscheduled the whole time.
1157 * The caller must ensure that the task *will* unschedule sometime soon,
1158 * else this function might spin for a *long* time. This function can't
1159 * be called with interrupts off, or it may introduce deadlock with
1160 * smp_call_function() if an IPI is sent by the same process we are
1161 * waiting to become inactive.
1163 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1165 unsigned long flags
;
1166 int running
, queued
;
1172 * We do the initial early heuristics without holding
1173 * any task-queue locks at all. We'll only try to get
1174 * the runqueue lock when things look like they will
1180 * If the task is actively running on another CPU
1181 * still, just relax and busy-wait without holding
1184 * NOTE! Since we don't hold any locks, it's not
1185 * even sure that "rq" stays as the right runqueue!
1186 * But we don't care, since "task_running()" will
1187 * return false if the runqueue has changed and p
1188 * is actually now running somewhere else!
1190 while (task_running(rq
, p
)) {
1191 if (match_state
&& unlikely(p
->state
!= match_state
))
1197 * Ok, time to look more closely! We need the rq
1198 * lock now, to be *sure*. If we're wrong, we'll
1199 * just go back and repeat.
1201 rq
= task_rq_lock(p
, &flags
);
1202 trace_sched_wait_task(p
);
1203 running
= task_running(rq
, p
);
1204 queued
= task_on_rq_queued(p
);
1206 if (!match_state
|| p
->state
== match_state
)
1207 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1208 task_rq_unlock(rq
, p
, &flags
);
1211 * If it changed from the expected state, bail out now.
1213 if (unlikely(!ncsw
))
1217 * Was it really running after all now that we
1218 * checked with the proper locks actually held?
1220 * Oops. Go back and try again..
1222 if (unlikely(running
)) {
1228 * It's not enough that it's not actively running,
1229 * it must be off the runqueue _entirely_, and not
1232 * So if it was still runnable (but just not actively
1233 * running right now), it's preempted, and we should
1234 * yield - it could be a while.
1236 if (unlikely(queued
)) {
1237 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1239 set_current_state(TASK_UNINTERRUPTIBLE
);
1240 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1245 * Ahh, all good. It wasn't running, and it wasn't
1246 * runnable, which means that it will never become
1247 * running in the future either. We're all done!
1256 * kick_process - kick a running thread to enter/exit the kernel
1257 * @p: the to-be-kicked thread
1259 * Cause a process which is running on another CPU to enter
1260 * kernel-mode, without any delay. (to get signals handled.)
1262 * NOTE: this function doesn't have to take the runqueue lock,
1263 * because all it wants to ensure is that the remote task enters
1264 * the kernel. If the IPI races and the task has been migrated
1265 * to another CPU then no harm is done and the purpose has been
1268 void kick_process(struct task_struct
*p
)
1274 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1275 smp_send_reschedule(cpu
);
1278 EXPORT_SYMBOL_GPL(kick_process
);
1279 #endif /* CONFIG_SMP */
1283 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1285 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1287 int nid
= cpu_to_node(cpu
);
1288 const struct cpumask
*nodemask
= NULL
;
1289 enum { cpuset
, possible
, fail
} state
= cpuset
;
1293 * If the node that the cpu is on has been offlined, cpu_to_node()
1294 * will return -1. There is no cpu on the node, and we should
1295 * select the cpu on the other node.
1298 nodemask
= cpumask_of_node(nid
);
1300 /* Look for allowed, online CPU in same node. */
1301 for_each_cpu(dest_cpu
, nodemask
) {
1302 if (!cpu_online(dest_cpu
))
1304 if (!cpu_active(dest_cpu
))
1306 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1312 /* Any allowed, online CPU? */
1313 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1314 if (!cpu_online(dest_cpu
))
1316 if (!cpu_active(dest_cpu
))
1323 /* No more Mr. Nice Guy. */
1324 cpuset_cpus_allowed_fallback(p
);
1329 do_set_cpus_allowed(p
, cpu_possible_mask
);
1340 if (state
!= cpuset
) {
1342 * Don't tell them about moving exiting tasks or
1343 * kernel threads (both mm NULL), since they never
1346 if (p
->mm
&& printk_ratelimit()) {
1347 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1348 task_pid_nr(p
), p
->comm
, cpu
);
1356 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1359 int select_task_rq(struct task_struct
*p
, int cpu
, int sd_flags
, int wake_flags
)
1361 if (p
->nr_cpus_allowed
> 1)
1362 cpu
= p
->sched_class
->select_task_rq(p
, cpu
, sd_flags
, wake_flags
);
1365 * In order not to call set_task_cpu() on a blocking task we need
1366 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1369 * Since this is common to all placement strategies, this lives here.
1371 * [ this allows ->select_task() to simply return task_cpu(p) and
1372 * not worry about this generic constraint ]
1374 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1376 cpu
= select_fallback_rq(task_cpu(p
), p
);
1381 static void update_avg(u64
*avg
, u64 sample
)
1383 s64 diff
= sample
- *avg
;
1389 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1391 #ifdef CONFIG_SCHEDSTATS
1392 struct rq
*rq
= this_rq();
1395 int this_cpu
= smp_processor_id();
1397 if (cpu
== this_cpu
) {
1398 schedstat_inc(rq
, ttwu_local
);
1399 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1401 struct sched_domain
*sd
;
1403 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1405 for_each_domain(this_cpu
, sd
) {
1406 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1407 schedstat_inc(sd
, ttwu_wake_remote
);
1414 if (wake_flags
& WF_MIGRATED
)
1415 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1417 #endif /* CONFIG_SMP */
1419 schedstat_inc(rq
, ttwu_count
);
1420 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1422 if (wake_flags
& WF_SYNC
)
1423 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1425 #endif /* CONFIG_SCHEDSTATS */
1428 static void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1430 activate_task(rq
, p
, en_flags
);
1431 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1433 /* if a worker is waking up, notify workqueue */
1434 if (p
->flags
& PF_WQ_WORKER
)
1435 wq_worker_waking_up(p
, cpu_of(rq
));
1439 * Mark the task runnable and perform wakeup-preemption.
1442 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1444 check_preempt_curr(rq
, p
, wake_flags
);
1445 trace_sched_wakeup(p
, true);
1447 p
->state
= TASK_RUNNING
;
1449 if (p
->sched_class
->task_woken
)
1450 p
->sched_class
->task_woken(rq
, p
);
1452 if (rq
->idle_stamp
) {
1453 u64 delta
= rq_clock(rq
) - rq
->idle_stamp
;
1454 u64 max
= 2*rq
->max_idle_balance_cost
;
1456 update_avg(&rq
->avg_idle
, delta
);
1458 if (rq
->avg_idle
> max
)
1467 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1470 if (p
->sched_contributes_to_load
)
1471 rq
->nr_uninterruptible
--;
1474 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1475 ttwu_do_wakeup(rq
, p
, wake_flags
);
1479 * Called in case the task @p isn't fully descheduled from its runqueue,
1480 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1481 * since all we need to do is flip p->state to TASK_RUNNING, since
1482 * the task is still ->on_rq.
1484 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1489 rq
= __task_rq_lock(p
);
1490 if (task_on_rq_queued(p
)) {
1491 /* check_preempt_curr() may use rq clock */
1492 update_rq_clock(rq
);
1493 ttwu_do_wakeup(rq
, p
, wake_flags
);
1496 __task_rq_unlock(rq
);
1502 void sched_ttwu_pending(void)
1504 struct rq
*rq
= this_rq();
1505 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1506 struct task_struct
*p
;
1507 unsigned long flags
;
1512 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1515 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1516 llist
= llist_next(llist
);
1517 ttwu_do_activate(rq
, p
, 0);
1520 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1523 void scheduler_ipi(void)
1526 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1527 * TIF_NEED_RESCHED remotely (for the first time) will also send
1530 preempt_fold_need_resched();
1532 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick())
1536 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1537 * traditionally all their work was done from the interrupt return
1538 * path. Now that we actually do some work, we need to make sure
1541 * Some archs already do call them, luckily irq_enter/exit nest
1544 * Arguably we should visit all archs and update all handlers,
1545 * however a fair share of IPIs are still resched only so this would
1546 * somewhat pessimize the simple resched case.
1549 sched_ttwu_pending();
1552 * Check if someone kicked us for doing the nohz idle load balance.
1554 if (unlikely(got_nohz_idle_kick())) {
1555 this_rq()->idle_balance
= 1;
1556 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1561 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1563 struct rq
*rq
= cpu_rq(cpu
);
1565 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
)) {
1566 if (!set_nr_if_polling(rq
->idle
))
1567 smp_send_reschedule(cpu
);
1569 trace_sched_wake_idle_without_ipi(cpu
);
1573 void wake_up_if_idle(int cpu
)
1575 struct rq
*rq
= cpu_rq(cpu
);
1576 unsigned long flags
;
1580 if (!is_idle_task(rcu_dereference(rq
->curr
)))
1583 if (set_nr_if_polling(rq
->idle
)) {
1584 trace_sched_wake_idle_without_ipi(cpu
);
1586 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1587 if (is_idle_task(rq
->curr
))
1588 smp_send_reschedule(cpu
);
1589 /* Else cpu is not in idle, do nothing here */
1590 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1597 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1599 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1601 #endif /* CONFIG_SMP */
1603 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1605 struct rq
*rq
= cpu_rq(cpu
);
1607 #if defined(CONFIG_SMP)
1608 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1609 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1610 ttwu_queue_remote(p
, cpu
);
1615 raw_spin_lock(&rq
->lock
);
1616 ttwu_do_activate(rq
, p
, 0);
1617 raw_spin_unlock(&rq
->lock
);
1621 * try_to_wake_up - wake up a thread
1622 * @p: the thread to be awakened
1623 * @state: the mask of task states that can be woken
1624 * @wake_flags: wake modifier flags (WF_*)
1626 * Put it on the run-queue if it's not already there. The "current"
1627 * thread is always on the run-queue (except when the actual
1628 * re-schedule is in progress), and as such you're allowed to do
1629 * the simpler "current->state = TASK_RUNNING" to mark yourself
1630 * runnable without the overhead of this.
1632 * Return: %true if @p was woken up, %false if it was already running.
1633 * or @state didn't match @p's state.
1636 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
1638 unsigned long flags
;
1639 int cpu
, success
= 0;
1642 * If we are going to wake up a thread waiting for CONDITION we
1643 * need to ensure that CONDITION=1 done by the caller can not be
1644 * reordered with p->state check below. This pairs with mb() in
1645 * set_current_state() the waiting thread does.
1647 smp_mb__before_spinlock();
1648 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1649 if (!(p
->state
& state
))
1652 success
= 1; /* we're going to change ->state */
1655 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
1660 * If the owning (remote) cpu is still in the middle of schedule() with
1661 * this task as prev, wait until its done referencing the task.
1666 * Pairs with the smp_wmb() in finish_lock_switch().
1670 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
1671 p
->state
= TASK_WAKING
;
1673 if (p
->sched_class
->task_waking
)
1674 p
->sched_class
->task_waking(p
);
1676 cpu
= select_task_rq(p
, p
->wake_cpu
, SD_BALANCE_WAKE
, wake_flags
);
1677 if (task_cpu(p
) != cpu
) {
1678 wake_flags
|= WF_MIGRATED
;
1679 set_task_cpu(p
, cpu
);
1681 #endif /* CONFIG_SMP */
1685 ttwu_stat(p
, cpu
, wake_flags
);
1687 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1693 * try_to_wake_up_local - try to wake up a local task with rq lock held
1694 * @p: the thread to be awakened
1696 * Put @p on the run-queue if it's not already there. The caller must
1697 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1700 static void try_to_wake_up_local(struct task_struct
*p
)
1702 struct rq
*rq
= task_rq(p
);
1704 if (WARN_ON_ONCE(rq
!= this_rq()) ||
1705 WARN_ON_ONCE(p
== current
))
1708 lockdep_assert_held(&rq
->lock
);
1710 if (!raw_spin_trylock(&p
->pi_lock
)) {
1711 raw_spin_unlock(&rq
->lock
);
1712 raw_spin_lock(&p
->pi_lock
);
1713 raw_spin_lock(&rq
->lock
);
1716 if (!(p
->state
& TASK_NORMAL
))
1719 if (!task_on_rq_queued(p
))
1720 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
1722 ttwu_do_wakeup(rq
, p
, 0);
1723 ttwu_stat(p
, smp_processor_id(), 0);
1725 raw_spin_unlock(&p
->pi_lock
);
1729 * wake_up_process - Wake up a specific process
1730 * @p: The process to be woken up.
1732 * Attempt to wake up the nominated process and move it to the set of runnable
1735 * Return: 1 if the process was woken up, 0 if it was already running.
1737 * It may be assumed that this function implies a write memory barrier before
1738 * changing the task state if and only if any tasks are woken up.
1740 int wake_up_process(struct task_struct
*p
)
1742 WARN_ON(task_is_stopped_or_traced(p
));
1743 return try_to_wake_up(p
, TASK_NORMAL
, 0);
1745 EXPORT_SYMBOL(wake_up_process
);
1747 int wake_up_state(struct task_struct
*p
, unsigned int state
)
1749 return try_to_wake_up(p
, state
, 0);
1753 * This function clears the sched_dl_entity static params.
1755 void __dl_clear_params(struct task_struct
*p
)
1757 struct sched_dl_entity
*dl_se
= &p
->dl
;
1759 dl_se
->dl_runtime
= 0;
1760 dl_se
->dl_deadline
= 0;
1761 dl_se
->dl_period
= 0;
1765 dl_se
->dl_throttled
= 0;
1767 dl_se
->dl_yielded
= 0;
1771 * Perform scheduler related setup for a newly forked process p.
1772 * p is forked by current.
1774 * __sched_fork() is basic setup used by init_idle() too:
1776 static void __sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
1781 p
->se
.exec_start
= 0;
1782 p
->se
.sum_exec_runtime
= 0;
1783 p
->se
.prev_sum_exec_runtime
= 0;
1784 p
->se
.nr_migrations
= 0;
1787 p
->se
.avg
.decay_count
= 0;
1789 INIT_LIST_HEAD(&p
->se
.group_node
);
1791 #ifdef CONFIG_SCHEDSTATS
1792 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
1795 RB_CLEAR_NODE(&p
->dl
.rb_node
);
1796 init_dl_task_timer(&p
->dl
);
1797 __dl_clear_params(p
);
1799 INIT_LIST_HEAD(&p
->rt
.run_list
);
1801 #ifdef CONFIG_PREEMPT_NOTIFIERS
1802 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1805 #ifdef CONFIG_NUMA_BALANCING
1806 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
1807 p
->mm
->numa_next_scan
= jiffies
+ msecs_to_jiffies(sysctl_numa_balancing_scan_delay
);
1808 p
->mm
->numa_scan_seq
= 0;
1811 if (clone_flags
& CLONE_VM
)
1812 p
->numa_preferred_nid
= current
->numa_preferred_nid
;
1814 p
->numa_preferred_nid
= -1;
1816 p
->node_stamp
= 0ULL;
1817 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
1818 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
1819 p
->numa_work
.next
= &p
->numa_work
;
1820 p
->numa_faults
= NULL
;
1821 p
->last_task_numa_placement
= 0;
1822 p
->last_sum_exec_runtime
= 0;
1824 p
->numa_group
= NULL
;
1825 #endif /* CONFIG_NUMA_BALANCING */
1828 #ifdef CONFIG_NUMA_BALANCING
1829 #ifdef CONFIG_SCHED_DEBUG
1830 void set_numabalancing_state(bool enabled
)
1833 sched_feat_set("NUMA");
1835 sched_feat_set("NO_NUMA");
1838 __read_mostly
bool numabalancing_enabled
;
1840 void set_numabalancing_state(bool enabled
)
1842 numabalancing_enabled
= enabled
;
1844 #endif /* CONFIG_SCHED_DEBUG */
1846 #ifdef CONFIG_PROC_SYSCTL
1847 int sysctl_numa_balancing(struct ctl_table
*table
, int write
,
1848 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
1852 int state
= numabalancing_enabled
;
1854 if (write
&& !capable(CAP_SYS_ADMIN
))
1859 err
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
1863 set_numabalancing_state(state
);
1870 * fork()/clone()-time setup:
1872 int sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
1874 unsigned long flags
;
1875 int cpu
= get_cpu();
1877 __sched_fork(clone_flags
, p
);
1879 * We mark the process as running here. This guarantees that
1880 * nobody will actually run it, and a signal or other external
1881 * event cannot wake it up and insert it on the runqueue either.
1883 p
->state
= TASK_RUNNING
;
1886 * Make sure we do not leak PI boosting priority to the child.
1888 p
->prio
= current
->normal_prio
;
1891 * Revert to default priority/policy on fork if requested.
1893 if (unlikely(p
->sched_reset_on_fork
)) {
1894 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
1895 p
->policy
= SCHED_NORMAL
;
1896 p
->static_prio
= NICE_TO_PRIO(0);
1898 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
1899 p
->static_prio
= NICE_TO_PRIO(0);
1901 p
->prio
= p
->normal_prio
= __normal_prio(p
);
1905 * We don't need the reset flag anymore after the fork. It has
1906 * fulfilled its duty:
1908 p
->sched_reset_on_fork
= 0;
1911 if (dl_prio(p
->prio
)) {
1914 } else if (rt_prio(p
->prio
)) {
1915 p
->sched_class
= &rt_sched_class
;
1917 p
->sched_class
= &fair_sched_class
;
1920 if (p
->sched_class
->task_fork
)
1921 p
->sched_class
->task_fork(p
);
1924 * The child is not yet in the pid-hash so no cgroup attach races,
1925 * and the cgroup is pinned to this child due to cgroup_fork()
1926 * is ran before sched_fork().
1928 * Silence PROVE_RCU.
1930 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
1931 set_task_cpu(p
, cpu
);
1932 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
1934 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1935 if (likely(sched_info_on()))
1936 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1938 #if defined(CONFIG_SMP)
1941 init_task_preempt_count(p
);
1943 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
1944 RB_CLEAR_NODE(&p
->pushable_dl_tasks
);
1951 unsigned long to_ratio(u64 period
, u64 runtime
)
1953 if (runtime
== RUNTIME_INF
)
1957 * Doing this here saves a lot of checks in all
1958 * the calling paths, and returning zero seems
1959 * safe for them anyway.
1964 return div64_u64(runtime
<< 20, period
);
1968 inline struct dl_bw
*dl_bw_of(int i
)
1970 rcu_lockdep_assert(rcu_read_lock_sched_held(),
1971 "sched RCU must be held");
1972 return &cpu_rq(i
)->rd
->dl_bw
;
1975 static inline int dl_bw_cpus(int i
)
1977 struct root_domain
*rd
= cpu_rq(i
)->rd
;
1980 rcu_lockdep_assert(rcu_read_lock_sched_held(),
1981 "sched RCU must be held");
1982 for_each_cpu_and(i
, rd
->span
, cpu_active_mask
)
1988 inline struct dl_bw
*dl_bw_of(int i
)
1990 return &cpu_rq(i
)->dl
.dl_bw
;
1993 static inline int dl_bw_cpus(int i
)
2000 * We must be sure that accepting a new task (or allowing changing the
2001 * parameters of an existing one) is consistent with the bandwidth
2002 * constraints. If yes, this function also accordingly updates the currently
2003 * allocated bandwidth to reflect the new situation.
2005 * This function is called while holding p's rq->lock.
2007 * XXX we should delay bw change until the task's 0-lag point, see
2010 static int dl_overflow(struct task_struct
*p
, int policy
,
2011 const struct sched_attr
*attr
)
2014 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
2015 u64 period
= attr
->sched_period
?: attr
->sched_deadline
;
2016 u64 runtime
= attr
->sched_runtime
;
2017 u64 new_bw
= dl_policy(policy
) ? to_ratio(period
, runtime
) : 0;
2020 if (new_bw
== p
->dl
.dl_bw
)
2024 * Either if a task, enters, leave, or stays -deadline but changes
2025 * its parameters, we may need to update accordingly the total
2026 * allocated bandwidth of the container.
2028 raw_spin_lock(&dl_b
->lock
);
2029 cpus
= dl_bw_cpus(task_cpu(p
));
2030 if (dl_policy(policy
) && !task_has_dl_policy(p
) &&
2031 !__dl_overflow(dl_b
, cpus
, 0, new_bw
)) {
2032 __dl_add(dl_b
, new_bw
);
2034 } else if (dl_policy(policy
) && task_has_dl_policy(p
) &&
2035 !__dl_overflow(dl_b
, cpus
, p
->dl
.dl_bw
, new_bw
)) {
2036 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2037 __dl_add(dl_b
, new_bw
);
2039 } else if (!dl_policy(policy
) && task_has_dl_policy(p
)) {
2040 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2043 raw_spin_unlock(&dl_b
->lock
);
2048 extern void init_dl_bw(struct dl_bw
*dl_b
);
2051 * wake_up_new_task - wake up a newly created task for the first time.
2053 * This function will do some initial scheduler statistics housekeeping
2054 * that must be done for every newly created context, then puts the task
2055 * on the runqueue and wakes it.
2057 void wake_up_new_task(struct task_struct
*p
)
2059 unsigned long flags
;
2062 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2065 * Fork balancing, do it here and not earlier because:
2066 * - cpus_allowed can change in the fork path
2067 * - any previously selected cpu might disappear through hotplug
2069 set_task_cpu(p
, select_task_rq(p
, task_cpu(p
), SD_BALANCE_FORK
, 0));
2072 /* Initialize new task's runnable average */
2073 init_task_runnable_average(p
);
2074 rq
= __task_rq_lock(p
);
2075 activate_task(rq
, p
, 0);
2076 p
->on_rq
= TASK_ON_RQ_QUEUED
;
2077 trace_sched_wakeup_new(p
, true);
2078 check_preempt_curr(rq
, p
, WF_FORK
);
2080 if (p
->sched_class
->task_woken
)
2081 p
->sched_class
->task_woken(rq
, p
);
2083 task_rq_unlock(rq
, p
, &flags
);
2086 #ifdef CONFIG_PREEMPT_NOTIFIERS
2089 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2090 * @notifier: notifier struct to register
2092 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2094 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2096 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2099 * preempt_notifier_unregister - no longer interested in preemption notifications
2100 * @notifier: notifier struct to unregister
2102 * This is safe to call from within a preemption notifier.
2104 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2106 hlist_del(¬ifier
->link
);
2108 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2110 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2112 struct preempt_notifier
*notifier
;
2114 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2115 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2119 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2120 struct task_struct
*next
)
2122 struct preempt_notifier
*notifier
;
2124 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2125 notifier
->ops
->sched_out(notifier
, next
);
2128 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2130 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2135 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2136 struct task_struct
*next
)
2140 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2143 * prepare_task_switch - prepare to switch tasks
2144 * @rq: the runqueue preparing to switch
2145 * @prev: the current task that is being switched out
2146 * @next: the task we are going to switch to.
2148 * This is called with the rq lock held and interrupts off. It must
2149 * be paired with a subsequent finish_task_switch after the context
2152 * prepare_task_switch sets up locking and calls architecture specific
2156 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
2157 struct task_struct
*next
)
2159 trace_sched_switch(prev
, next
);
2160 sched_info_switch(rq
, prev
, next
);
2161 perf_event_task_sched_out(prev
, next
);
2162 fire_sched_out_preempt_notifiers(prev
, next
);
2163 prepare_lock_switch(rq
, next
);
2164 prepare_arch_switch(next
);
2168 * finish_task_switch - clean up after a task-switch
2169 * @prev: the thread we just switched away from.
2171 * finish_task_switch must be called after the context switch, paired
2172 * with a prepare_task_switch call before the context switch.
2173 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2174 * and do any other architecture-specific cleanup actions.
2176 * Note that we may have delayed dropping an mm in context_switch(). If
2177 * so, we finish that here outside of the runqueue lock. (Doing it
2178 * with the lock held can cause deadlocks; see schedule() for
2181 * The context switch have flipped the stack from under us and restored the
2182 * local variables which were saved when this task called schedule() in the
2183 * past. prev == current is still correct but we need to recalculate this_rq
2184 * because prev may have moved to another CPU.
2186 static struct rq
*finish_task_switch(struct task_struct
*prev
)
2187 __releases(rq
->lock
)
2189 struct rq
*rq
= this_rq();
2190 struct mm_struct
*mm
= rq
->prev_mm
;
2196 * A task struct has one reference for the use as "current".
2197 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2198 * schedule one last time. The schedule call will never return, and
2199 * the scheduled task must drop that reference.
2200 * The test for TASK_DEAD must occur while the runqueue locks are
2201 * still held, otherwise prev could be scheduled on another cpu, die
2202 * there before we look at prev->state, and then the reference would
2204 * Manfred Spraul <manfred@colorfullife.com>
2206 prev_state
= prev
->state
;
2207 vtime_task_switch(prev
);
2208 finish_arch_switch(prev
);
2209 perf_event_task_sched_in(prev
, current
);
2210 finish_lock_switch(rq
, prev
);
2211 finish_arch_post_lock_switch();
2213 fire_sched_in_preempt_notifiers(current
);
2216 if (unlikely(prev_state
== TASK_DEAD
)) {
2217 if (prev
->sched_class
->task_dead
)
2218 prev
->sched_class
->task_dead(prev
);
2221 * Remove function-return probe instances associated with this
2222 * task and put them back on the free list.
2224 kprobe_flush_task(prev
);
2225 put_task_struct(prev
);
2228 tick_nohz_task_switch(current
);
2234 /* rq->lock is NOT held, but preemption is disabled */
2235 static inline void post_schedule(struct rq
*rq
)
2237 if (rq
->post_schedule
) {
2238 unsigned long flags
;
2240 raw_spin_lock_irqsave(&rq
->lock
, flags
);
2241 if (rq
->curr
->sched_class
->post_schedule
)
2242 rq
->curr
->sched_class
->post_schedule(rq
);
2243 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
2245 rq
->post_schedule
= 0;
2251 static inline void post_schedule(struct rq
*rq
)
2258 * schedule_tail - first thing a freshly forked thread must call.
2259 * @prev: the thread we just switched away from.
2261 asmlinkage __visible
void schedule_tail(struct task_struct
*prev
)
2262 __releases(rq
->lock
)
2266 /* finish_task_switch() drops rq->lock and enables preemtion */
2268 rq
= finish_task_switch(prev
);
2272 if (current
->set_child_tid
)
2273 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2277 * context_switch - switch to the new MM and the new thread's register state.
2279 static inline struct rq
*
2280 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2281 struct task_struct
*next
)
2283 struct mm_struct
*mm
, *oldmm
;
2285 prepare_task_switch(rq
, prev
, next
);
2288 oldmm
= prev
->active_mm
;
2290 * For paravirt, this is coupled with an exit in switch_to to
2291 * combine the page table reload and the switch backend into
2294 arch_start_context_switch(prev
);
2297 next
->active_mm
= oldmm
;
2298 atomic_inc(&oldmm
->mm_count
);
2299 enter_lazy_tlb(oldmm
, next
);
2301 switch_mm(oldmm
, mm
, next
);
2304 prev
->active_mm
= NULL
;
2305 rq
->prev_mm
= oldmm
;
2308 * Since the runqueue lock will be released by the next
2309 * task (which is an invalid locking op but in the case
2310 * of the scheduler it's an obvious special-case), so we
2311 * do an early lockdep release here:
2313 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2315 context_tracking_task_switch(prev
, next
);
2316 /* Here we just switch the register state and the stack. */
2317 switch_to(prev
, next
, prev
);
2320 return finish_task_switch(prev
);
2324 * nr_running and nr_context_switches:
2326 * externally visible scheduler statistics: current number of runnable
2327 * threads, total number of context switches performed since bootup.
2329 unsigned long nr_running(void)
2331 unsigned long i
, sum
= 0;
2333 for_each_online_cpu(i
)
2334 sum
+= cpu_rq(i
)->nr_running
;
2340 * Check if only the current task is running on the cpu.
2342 bool single_task_running(void)
2344 if (cpu_rq(smp_processor_id())->nr_running
== 1)
2349 EXPORT_SYMBOL(single_task_running
);
2351 unsigned long long nr_context_switches(void)
2354 unsigned long long sum
= 0;
2356 for_each_possible_cpu(i
)
2357 sum
+= cpu_rq(i
)->nr_switches
;
2362 unsigned long nr_iowait(void)
2364 unsigned long i
, sum
= 0;
2366 for_each_possible_cpu(i
)
2367 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2372 unsigned long nr_iowait_cpu(int cpu
)
2374 struct rq
*this = cpu_rq(cpu
);
2375 return atomic_read(&this->nr_iowait
);
2378 void get_iowait_load(unsigned long *nr_waiters
, unsigned long *load
)
2380 struct rq
*this = this_rq();
2381 *nr_waiters
= atomic_read(&this->nr_iowait
);
2382 *load
= this->cpu_load
[0];
2388 * sched_exec - execve() is a valuable balancing opportunity, because at
2389 * this point the task has the smallest effective memory and cache footprint.
2391 void sched_exec(void)
2393 struct task_struct
*p
= current
;
2394 unsigned long flags
;
2397 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2398 dest_cpu
= p
->sched_class
->select_task_rq(p
, task_cpu(p
), SD_BALANCE_EXEC
, 0);
2399 if (dest_cpu
== smp_processor_id())
2402 if (likely(cpu_active(dest_cpu
))) {
2403 struct migration_arg arg
= { p
, dest_cpu
};
2405 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2406 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2410 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2415 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2416 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2418 EXPORT_PER_CPU_SYMBOL(kstat
);
2419 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2422 * Return accounted runtime for the task.
2423 * In case the task is currently running, return the runtime plus current's
2424 * pending runtime that have not been accounted yet.
2426 unsigned long long task_sched_runtime(struct task_struct
*p
)
2428 unsigned long flags
;
2432 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2434 * 64-bit doesn't need locks to atomically read a 64bit value.
2435 * So we have a optimization chance when the task's delta_exec is 0.
2436 * Reading ->on_cpu is racy, but this is ok.
2438 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2439 * If we race with it entering cpu, unaccounted time is 0. This is
2440 * indistinguishable from the read occurring a few cycles earlier.
2441 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2442 * been accounted, so we're correct here as well.
2444 if (!p
->on_cpu
|| !task_on_rq_queued(p
))
2445 return p
->se
.sum_exec_runtime
;
2448 rq
= task_rq_lock(p
, &flags
);
2450 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2451 * project cycles that may never be accounted to this
2452 * thread, breaking clock_gettime().
2454 if (task_current(rq
, p
) && task_on_rq_queued(p
)) {
2455 update_rq_clock(rq
);
2456 p
->sched_class
->update_curr(rq
);
2458 ns
= p
->se
.sum_exec_runtime
;
2459 task_rq_unlock(rq
, p
, &flags
);
2465 * This function gets called by the timer code, with HZ frequency.
2466 * We call it with interrupts disabled.
2468 void scheduler_tick(void)
2470 int cpu
= smp_processor_id();
2471 struct rq
*rq
= cpu_rq(cpu
);
2472 struct task_struct
*curr
= rq
->curr
;
2476 raw_spin_lock(&rq
->lock
);
2477 update_rq_clock(rq
);
2478 curr
->sched_class
->task_tick(rq
, curr
, 0);
2479 update_cpu_load_active(rq
);
2480 raw_spin_unlock(&rq
->lock
);
2482 perf_event_task_tick();
2485 rq
->idle_balance
= idle_cpu(cpu
);
2486 trigger_load_balance(rq
);
2488 rq_last_tick_reset(rq
);
2491 #ifdef CONFIG_NO_HZ_FULL
2493 * scheduler_tick_max_deferment
2495 * Keep at least one tick per second when a single
2496 * active task is running because the scheduler doesn't
2497 * yet completely support full dynticks environment.
2499 * This makes sure that uptime, CFS vruntime, load
2500 * balancing, etc... continue to move forward, even
2501 * with a very low granularity.
2503 * Return: Maximum deferment in nanoseconds.
2505 u64
scheduler_tick_max_deferment(void)
2507 struct rq
*rq
= this_rq();
2508 unsigned long next
, now
= ACCESS_ONCE(jiffies
);
2510 next
= rq
->last_sched_tick
+ HZ
;
2512 if (time_before_eq(next
, now
))
2515 return jiffies_to_nsecs(next
- now
);
2519 notrace
unsigned long get_parent_ip(unsigned long addr
)
2521 if (in_lock_functions(addr
)) {
2522 addr
= CALLER_ADDR2
;
2523 if (in_lock_functions(addr
))
2524 addr
= CALLER_ADDR3
;
2529 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2530 defined(CONFIG_PREEMPT_TRACER))
2532 void preempt_count_add(int val
)
2534 #ifdef CONFIG_DEBUG_PREEMPT
2538 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2541 __preempt_count_add(val
);
2542 #ifdef CONFIG_DEBUG_PREEMPT
2544 * Spinlock count overflowing soon?
2546 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
2549 if (preempt_count() == val
) {
2550 unsigned long ip
= get_parent_ip(CALLER_ADDR1
);
2551 #ifdef CONFIG_DEBUG_PREEMPT
2552 current
->preempt_disable_ip
= ip
;
2554 trace_preempt_off(CALLER_ADDR0
, ip
);
2557 EXPORT_SYMBOL(preempt_count_add
);
2558 NOKPROBE_SYMBOL(preempt_count_add
);
2560 void preempt_count_sub(int val
)
2562 #ifdef CONFIG_DEBUG_PREEMPT
2566 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
2569 * Is the spinlock portion underflowing?
2571 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
2572 !(preempt_count() & PREEMPT_MASK
)))
2576 if (preempt_count() == val
)
2577 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
2578 __preempt_count_sub(val
);
2580 EXPORT_SYMBOL(preempt_count_sub
);
2581 NOKPROBE_SYMBOL(preempt_count_sub
);
2586 * Print scheduling while atomic bug:
2588 static noinline
void __schedule_bug(struct task_struct
*prev
)
2590 if (oops_in_progress
)
2593 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
2594 prev
->comm
, prev
->pid
, preempt_count());
2596 debug_show_held_locks(prev
);
2598 if (irqs_disabled())
2599 print_irqtrace_events(prev
);
2600 #ifdef CONFIG_DEBUG_PREEMPT
2601 if (in_atomic_preempt_off()) {
2602 pr_err("Preemption disabled at:");
2603 print_ip_sym(current
->preempt_disable_ip
);
2608 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
2612 * Various schedule()-time debugging checks and statistics:
2614 static inline void schedule_debug(struct task_struct
*prev
)
2616 #ifdef CONFIG_SCHED_STACK_END_CHECK
2617 BUG_ON(unlikely(task_stack_end_corrupted(prev
)));
2620 * Test if we are atomic. Since do_exit() needs to call into
2621 * schedule() atomically, we ignore that path. Otherwise whine
2622 * if we are scheduling when we should not.
2624 if (unlikely(in_atomic_preempt_off() && prev
->state
!= TASK_DEAD
))
2625 __schedule_bug(prev
);
2628 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2630 schedstat_inc(this_rq(), sched_count
);
2634 * Pick up the highest-prio task:
2636 static inline struct task_struct
*
2637 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
2639 const struct sched_class
*class = &fair_sched_class
;
2640 struct task_struct
*p
;
2643 * Optimization: we know that if all tasks are in
2644 * the fair class we can call that function directly:
2646 if (likely(prev
->sched_class
== class &&
2647 rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
2648 p
= fair_sched_class
.pick_next_task(rq
, prev
);
2649 if (unlikely(p
== RETRY_TASK
))
2652 /* assumes fair_sched_class->next == idle_sched_class */
2654 p
= idle_sched_class
.pick_next_task(rq
, prev
);
2660 for_each_class(class) {
2661 p
= class->pick_next_task(rq
, prev
);
2663 if (unlikely(p
== RETRY_TASK
))
2669 BUG(); /* the idle class will always have a runnable task */
2673 * __schedule() is the main scheduler function.
2675 * The main means of driving the scheduler and thus entering this function are:
2677 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2679 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2680 * paths. For example, see arch/x86/entry_64.S.
2682 * To drive preemption between tasks, the scheduler sets the flag in timer
2683 * interrupt handler scheduler_tick().
2685 * 3. Wakeups don't really cause entry into schedule(). They add a
2686 * task to the run-queue and that's it.
2688 * Now, if the new task added to the run-queue preempts the current
2689 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2690 * called on the nearest possible occasion:
2692 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
2694 * - in syscall or exception context, at the next outmost
2695 * preempt_enable(). (this might be as soon as the wake_up()'s
2698 * - in IRQ context, return from interrupt-handler to
2699 * preemptible context
2701 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2704 * - cond_resched() call
2705 * - explicit schedule() call
2706 * - return from syscall or exception to user-space
2707 * - return from interrupt-handler to user-space
2709 * WARNING: all callers must re-check need_resched() afterward and reschedule
2710 * accordingly in case an event triggered the need for rescheduling (such as
2711 * an interrupt waking up a task) while preemption was disabled in __schedule().
2713 static void __sched
__schedule(void)
2715 struct task_struct
*prev
, *next
;
2716 unsigned long *switch_count
;
2721 cpu
= smp_processor_id();
2723 rcu_note_context_switch();
2726 schedule_debug(prev
);
2728 if (sched_feat(HRTICK
))
2732 * Make sure that signal_pending_state()->signal_pending() below
2733 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
2734 * done by the caller to avoid the race with signal_wake_up().
2736 smp_mb__before_spinlock();
2737 raw_spin_lock_irq(&rq
->lock
);
2739 rq
->clock_skip_update
<<= 1; /* promote REQ to ACT */
2741 switch_count
= &prev
->nivcsw
;
2742 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2743 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
2744 prev
->state
= TASK_RUNNING
;
2746 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
2750 * If a worker went to sleep, notify and ask workqueue
2751 * whether it wants to wake up a task to maintain
2754 if (prev
->flags
& PF_WQ_WORKER
) {
2755 struct task_struct
*to_wakeup
;
2757 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
2759 try_to_wake_up_local(to_wakeup
);
2762 switch_count
= &prev
->nvcsw
;
2765 if (task_on_rq_queued(prev
))
2766 update_rq_clock(rq
);
2768 next
= pick_next_task(rq
, prev
);
2769 clear_tsk_need_resched(prev
);
2770 clear_preempt_need_resched();
2771 rq
->clock_skip_update
= 0;
2773 if (likely(prev
!= next
)) {
2778 rq
= context_switch(rq
, prev
, next
); /* unlocks the rq */
2781 raw_spin_unlock_irq(&rq
->lock
);
2785 sched_preempt_enable_no_resched();
2788 static inline void sched_submit_work(struct task_struct
*tsk
)
2790 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
2793 * If we are going to sleep and we have plugged IO queued,
2794 * make sure to submit it to avoid deadlocks.
2796 if (blk_needs_flush_plug(tsk
))
2797 blk_schedule_flush_plug(tsk
);
2800 asmlinkage __visible
void __sched
schedule(void)
2802 struct task_struct
*tsk
= current
;
2804 sched_submit_work(tsk
);
2807 } while (need_resched());
2809 EXPORT_SYMBOL(schedule
);
2811 #ifdef CONFIG_CONTEXT_TRACKING
2812 asmlinkage __visible
void __sched
schedule_user(void)
2815 * If we come here after a random call to set_need_resched(),
2816 * or we have been woken up remotely but the IPI has not yet arrived,
2817 * we haven't yet exited the RCU idle mode. Do it here manually until
2818 * we find a better solution.
2820 * NB: There are buggy callers of this function. Ideally we
2821 * should warn if prev_state != IN_USER, but that will trigger
2822 * too frequently to make sense yet.
2824 enum ctx_state prev_state
= exception_enter();
2826 exception_exit(prev_state
);
2831 * schedule_preempt_disabled - called with preemption disabled
2833 * Returns with preemption disabled. Note: preempt_count must be 1
2835 void __sched
schedule_preempt_disabled(void)
2837 sched_preempt_enable_no_resched();
2842 static void __sched notrace
preempt_schedule_common(void)
2845 __preempt_count_add(PREEMPT_ACTIVE
);
2847 __preempt_count_sub(PREEMPT_ACTIVE
);
2850 * Check again in case we missed a preemption opportunity
2851 * between schedule and now.
2854 } while (need_resched());
2857 #ifdef CONFIG_PREEMPT
2859 * this is the entry point to schedule() from in-kernel preemption
2860 * off of preempt_enable. Kernel preemptions off return from interrupt
2861 * occur there and call schedule directly.
2863 asmlinkage __visible
void __sched notrace
preempt_schedule(void)
2866 * If there is a non-zero preempt_count or interrupts are disabled,
2867 * we do not want to preempt the current task. Just return..
2869 if (likely(!preemptible()))
2872 preempt_schedule_common();
2874 NOKPROBE_SYMBOL(preempt_schedule
);
2875 EXPORT_SYMBOL(preempt_schedule
);
2877 #ifdef CONFIG_CONTEXT_TRACKING
2879 * preempt_schedule_context - preempt_schedule called by tracing
2881 * The tracing infrastructure uses preempt_enable_notrace to prevent
2882 * recursion and tracing preempt enabling caused by the tracing
2883 * infrastructure itself. But as tracing can happen in areas coming
2884 * from userspace or just about to enter userspace, a preempt enable
2885 * can occur before user_exit() is called. This will cause the scheduler
2886 * to be called when the system is still in usermode.
2888 * To prevent this, the preempt_enable_notrace will use this function
2889 * instead of preempt_schedule() to exit user context if needed before
2890 * calling the scheduler.
2892 asmlinkage __visible
void __sched notrace
preempt_schedule_context(void)
2894 enum ctx_state prev_ctx
;
2896 if (likely(!preemptible()))
2900 __preempt_count_add(PREEMPT_ACTIVE
);
2902 * Needs preempt disabled in case user_exit() is traced
2903 * and the tracer calls preempt_enable_notrace() causing
2904 * an infinite recursion.
2906 prev_ctx
= exception_enter();
2908 exception_exit(prev_ctx
);
2910 __preempt_count_sub(PREEMPT_ACTIVE
);
2912 } while (need_resched());
2914 EXPORT_SYMBOL_GPL(preempt_schedule_context
);
2915 #endif /* CONFIG_CONTEXT_TRACKING */
2917 #endif /* CONFIG_PREEMPT */
2920 * this is the entry point to schedule() from kernel preemption
2921 * off of irq context.
2922 * Note, that this is called and return with irqs disabled. This will
2923 * protect us against recursive calling from irq.
2925 asmlinkage __visible
void __sched
preempt_schedule_irq(void)
2927 enum ctx_state prev_state
;
2929 /* Catch callers which need to be fixed */
2930 BUG_ON(preempt_count() || !irqs_disabled());
2932 prev_state
= exception_enter();
2935 __preempt_count_add(PREEMPT_ACTIVE
);
2938 local_irq_disable();
2939 __preempt_count_sub(PREEMPT_ACTIVE
);
2942 * Check again in case we missed a preemption opportunity
2943 * between schedule and now.
2946 } while (need_resched());
2948 exception_exit(prev_state
);
2951 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
2954 return try_to_wake_up(curr
->private, mode
, wake_flags
);
2956 EXPORT_SYMBOL(default_wake_function
);
2958 #ifdef CONFIG_RT_MUTEXES
2961 * rt_mutex_setprio - set the current priority of a task
2963 * @prio: prio value (kernel-internal form)
2965 * This function changes the 'effective' priority of a task. It does
2966 * not touch ->normal_prio like __setscheduler().
2968 * Used by the rt_mutex code to implement priority inheritance
2969 * logic. Call site only calls if the priority of the task changed.
2971 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
2973 int oldprio
, queued
, running
, enqueue_flag
= 0;
2975 const struct sched_class
*prev_class
;
2977 BUG_ON(prio
> MAX_PRIO
);
2979 rq
= __task_rq_lock(p
);
2982 * Idle task boosting is a nono in general. There is one
2983 * exception, when PREEMPT_RT and NOHZ is active:
2985 * The idle task calls get_next_timer_interrupt() and holds
2986 * the timer wheel base->lock on the CPU and another CPU wants
2987 * to access the timer (probably to cancel it). We can safely
2988 * ignore the boosting request, as the idle CPU runs this code
2989 * with interrupts disabled and will complete the lock
2990 * protected section without being interrupted. So there is no
2991 * real need to boost.
2993 if (unlikely(p
== rq
->idle
)) {
2994 WARN_ON(p
!= rq
->curr
);
2995 WARN_ON(p
->pi_blocked_on
);
2999 trace_sched_pi_setprio(p
, prio
);
3001 prev_class
= p
->sched_class
;
3002 queued
= task_on_rq_queued(p
);
3003 running
= task_current(rq
, p
);
3005 dequeue_task(rq
, p
, 0);
3007 put_prev_task(rq
, p
);
3010 * Boosting condition are:
3011 * 1. -rt task is running and holds mutex A
3012 * --> -dl task blocks on mutex A
3014 * 2. -dl task is running and holds mutex A
3015 * --> -dl task blocks on mutex A and could preempt the
3018 if (dl_prio(prio
)) {
3019 struct task_struct
*pi_task
= rt_mutex_get_top_task(p
);
3020 if (!dl_prio(p
->normal_prio
) ||
3021 (pi_task
&& dl_entity_preempt(&pi_task
->dl
, &p
->dl
))) {
3022 p
->dl
.dl_boosted
= 1;
3023 p
->dl
.dl_throttled
= 0;
3024 enqueue_flag
= ENQUEUE_REPLENISH
;
3026 p
->dl
.dl_boosted
= 0;
3027 p
->sched_class
= &dl_sched_class
;
3028 } else if (rt_prio(prio
)) {
3029 if (dl_prio(oldprio
))
3030 p
->dl
.dl_boosted
= 0;
3032 enqueue_flag
= ENQUEUE_HEAD
;
3033 p
->sched_class
= &rt_sched_class
;
3035 if (dl_prio(oldprio
))
3036 p
->dl
.dl_boosted
= 0;
3037 p
->sched_class
= &fair_sched_class
;
3043 p
->sched_class
->set_curr_task(rq
);
3045 enqueue_task(rq
, p
, enqueue_flag
);
3047 check_class_changed(rq
, p
, prev_class
, oldprio
);
3049 __task_rq_unlock(rq
);
3053 void set_user_nice(struct task_struct
*p
, long nice
)
3055 int old_prio
, delta
, queued
;
3056 unsigned long flags
;
3059 if (task_nice(p
) == nice
|| nice
< MIN_NICE
|| nice
> MAX_NICE
)
3062 * We have to be careful, if called from sys_setpriority(),
3063 * the task might be in the middle of scheduling on another CPU.
3065 rq
= task_rq_lock(p
, &flags
);
3067 * The RT priorities are set via sched_setscheduler(), but we still
3068 * allow the 'normal' nice value to be set - but as expected
3069 * it wont have any effect on scheduling until the task is
3070 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3072 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
3073 p
->static_prio
= NICE_TO_PRIO(nice
);
3076 queued
= task_on_rq_queued(p
);
3078 dequeue_task(rq
, p
, 0);
3080 p
->static_prio
= NICE_TO_PRIO(nice
);
3083 p
->prio
= effective_prio(p
);
3084 delta
= p
->prio
- old_prio
;
3087 enqueue_task(rq
, p
, 0);
3089 * If the task increased its priority or is running and
3090 * lowered its priority, then reschedule its CPU:
3092 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3096 task_rq_unlock(rq
, p
, &flags
);
3098 EXPORT_SYMBOL(set_user_nice
);
3101 * can_nice - check if a task can reduce its nice value
3105 int can_nice(const struct task_struct
*p
, const int nice
)
3107 /* convert nice value [19,-20] to rlimit style value [1,40] */
3108 int nice_rlim
= nice_to_rlimit(nice
);
3110 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3111 capable(CAP_SYS_NICE
));
3114 #ifdef __ARCH_WANT_SYS_NICE
3117 * sys_nice - change the priority of the current process.
3118 * @increment: priority increment
3120 * sys_setpriority is a more generic, but much slower function that
3121 * does similar things.
3123 SYSCALL_DEFINE1(nice
, int, increment
)
3128 * Setpriority might change our priority at the same moment.
3129 * We don't have to worry. Conceptually one call occurs first
3130 * and we have a single winner.
3132 increment
= clamp(increment
, -NICE_WIDTH
, NICE_WIDTH
);
3133 nice
= task_nice(current
) + increment
;
3135 nice
= clamp_val(nice
, MIN_NICE
, MAX_NICE
);
3136 if (increment
< 0 && !can_nice(current
, nice
))
3139 retval
= security_task_setnice(current
, nice
);
3143 set_user_nice(current
, nice
);
3150 * task_prio - return the priority value of a given task.
3151 * @p: the task in question.
3153 * Return: The priority value as seen by users in /proc.
3154 * RT tasks are offset by -200. Normal tasks are centered
3155 * around 0, value goes from -16 to +15.
3157 int task_prio(const struct task_struct
*p
)
3159 return p
->prio
- MAX_RT_PRIO
;
3163 * idle_cpu - is a given cpu idle currently?
3164 * @cpu: the processor in question.
3166 * Return: 1 if the CPU is currently idle. 0 otherwise.
3168 int idle_cpu(int cpu
)
3170 struct rq
*rq
= cpu_rq(cpu
);
3172 if (rq
->curr
!= rq
->idle
)
3179 if (!llist_empty(&rq
->wake_list
))
3187 * idle_task - return the idle task for a given cpu.
3188 * @cpu: the processor in question.
3190 * Return: The idle task for the cpu @cpu.
3192 struct task_struct
*idle_task(int cpu
)
3194 return cpu_rq(cpu
)->idle
;
3198 * find_process_by_pid - find a process with a matching PID value.
3199 * @pid: the pid in question.
3201 * The task of @pid, if found. %NULL otherwise.
3203 static struct task_struct
*find_process_by_pid(pid_t pid
)
3205 return pid
? find_task_by_vpid(pid
) : current
;
3209 * This function initializes the sched_dl_entity of a newly becoming
3210 * SCHED_DEADLINE task.
3212 * Only the static values are considered here, the actual runtime and the
3213 * absolute deadline will be properly calculated when the task is enqueued
3214 * for the first time with its new policy.
3217 __setparam_dl(struct task_struct
*p
, const struct sched_attr
*attr
)
3219 struct sched_dl_entity
*dl_se
= &p
->dl
;
3221 dl_se
->dl_runtime
= attr
->sched_runtime
;
3222 dl_se
->dl_deadline
= attr
->sched_deadline
;
3223 dl_se
->dl_period
= attr
->sched_period
?: dl_se
->dl_deadline
;
3224 dl_se
->flags
= attr
->sched_flags
;
3225 dl_se
->dl_bw
= to_ratio(dl_se
->dl_period
, dl_se
->dl_runtime
);
3228 * Changing the parameters of a task is 'tricky' and we're not doing
3229 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3231 * What we SHOULD do is delay the bandwidth release until the 0-lag
3232 * point. This would include retaining the task_struct until that time
3233 * and change dl_overflow() to not immediately decrement the current
3236 * Instead we retain the current runtime/deadline and let the new
3237 * parameters take effect after the current reservation period lapses.
3238 * This is safe (albeit pessimistic) because the 0-lag point is always
3239 * before the current scheduling deadline.
3241 * We can still have temporary overloads because we do not delay the
3242 * change in bandwidth until that time; so admission control is
3243 * not on the safe side. It does however guarantee tasks will never
3244 * consume more than promised.
3249 * sched_setparam() passes in -1 for its policy, to let the functions
3250 * it calls know not to change it.
3252 #define SETPARAM_POLICY -1
3254 static void __setscheduler_params(struct task_struct
*p
,
3255 const struct sched_attr
*attr
)
3257 int policy
= attr
->sched_policy
;
3259 if (policy
== SETPARAM_POLICY
)
3264 if (dl_policy(policy
))
3265 __setparam_dl(p
, attr
);
3266 else if (fair_policy(policy
))
3267 p
->static_prio
= NICE_TO_PRIO(attr
->sched_nice
);
3270 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3271 * !rt_policy. Always setting this ensures that things like
3272 * getparam()/getattr() don't report silly values for !rt tasks.
3274 p
->rt_priority
= attr
->sched_priority
;
3275 p
->normal_prio
= normal_prio(p
);
3279 /* Actually do priority change: must hold pi & rq lock. */
3280 static void __setscheduler(struct rq
*rq
, struct task_struct
*p
,
3281 const struct sched_attr
*attr
)
3283 __setscheduler_params(p
, attr
);
3286 * If we get here, there was no pi waiters boosting the
3287 * task. It is safe to use the normal prio.
3289 p
->prio
= normal_prio(p
);
3291 if (dl_prio(p
->prio
))
3292 p
->sched_class
= &dl_sched_class
;
3293 else if (rt_prio(p
->prio
))
3294 p
->sched_class
= &rt_sched_class
;
3296 p
->sched_class
= &fair_sched_class
;
3300 __getparam_dl(struct task_struct
*p
, struct sched_attr
*attr
)
3302 struct sched_dl_entity
*dl_se
= &p
->dl
;
3304 attr
->sched_priority
= p
->rt_priority
;
3305 attr
->sched_runtime
= dl_se
->dl_runtime
;
3306 attr
->sched_deadline
= dl_se
->dl_deadline
;
3307 attr
->sched_period
= dl_se
->dl_period
;
3308 attr
->sched_flags
= dl_se
->flags
;
3312 * This function validates the new parameters of a -deadline task.
3313 * We ask for the deadline not being zero, and greater or equal
3314 * than the runtime, as well as the period of being zero or
3315 * greater than deadline. Furthermore, we have to be sure that
3316 * user parameters are above the internal resolution of 1us (we
3317 * check sched_runtime only since it is always the smaller one) and
3318 * below 2^63 ns (we have to check both sched_deadline and
3319 * sched_period, as the latter can be zero).
3322 __checkparam_dl(const struct sched_attr
*attr
)
3325 if (attr
->sched_deadline
== 0)
3329 * Since we truncate DL_SCALE bits, make sure we're at least
3332 if (attr
->sched_runtime
< (1ULL << DL_SCALE
))
3336 * Since we use the MSB for wrap-around and sign issues, make
3337 * sure it's not set (mind that period can be equal to zero).
3339 if (attr
->sched_deadline
& (1ULL << 63) ||
3340 attr
->sched_period
& (1ULL << 63))
3343 /* runtime <= deadline <= period (if period != 0) */
3344 if ((attr
->sched_period
!= 0 &&
3345 attr
->sched_period
< attr
->sched_deadline
) ||
3346 attr
->sched_deadline
< attr
->sched_runtime
)
3353 * check the target process has a UID that matches the current process's
3355 static bool check_same_owner(struct task_struct
*p
)
3357 const struct cred
*cred
= current_cred(), *pcred
;
3361 pcred
= __task_cred(p
);
3362 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3363 uid_eq(cred
->euid
, pcred
->uid
));
3368 static bool dl_param_changed(struct task_struct
*p
,
3369 const struct sched_attr
*attr
)
3371 struct sched_dl_entity
*dl_se
= &p
->dl
;
3373 if (dl_se
->dl_runtime
!= attr
->sched_runtime
||
3374 dl_se
->dl_deadline
!= attr
->sched_deadline
||
3375 dl_se
->dl_period
!= attr
->sched_period
||
3376 dl_se
->flags
!= attr
->sched_flags
)
3382 static int __sched_setscheduler(struct task_struct
*p
,
3383 const struct sched_attr
*attr
,
3386 int newprio
= dl_policy(attr
->sched_policy
) ? MAX_DL_PRIO
- 1 :
3387 MAX_RT_PRIO
- 1 - attr
->sched_priority
;
3388 int retval
, oldprio
, oldpolicy
= -1, queued
, running
;
3389 int policy
= attr
->sched_policy
;
3390 unsigned long flags
;
3391 const struct sched_class
*prev_class
;
3395 /* may grab non-irq protected spin_locks */
3396 BUG_ON(in_interrupt());
3398 /* double check policy once rq lock held */
3400 reset_on_fork
= p
->sched_reset_on_fork
;
3401 policy
= oldpolicy
= p
->policy
;
3403 reset_on_fork
= !!(attr
->sched_flags
& SCHED_FLAG_RESET_ON_FORK
);
3405 if (policy
!= SCHED_DEADLINE
&&
3406 policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3407 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
3408 policy
!= SCHED_IDLE
)
3412 if (attr
->sched_flags
& ~(SCHED_FLAG_RESET_ON_FORK
))
3416 * Valid priorities for SCHED_FIFO and SCHED_RR are
3417 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3418 * SCHED_BATCH and SCHED_IDLE is 0.
3420 if ((p
->mm
&& attr
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3421 (!p
->mm
&& attr
->sched_priority
> MAX_RT_PRIO
-1))
3423 if ((dl_policy(policy
) && !__checkparam_dl(attr
)) ||
3424 (rt_policy(policy
) != (attr
->sched_priority
!= 0)))
3428 * Allow unprivileged RT tasks to decrease priority:
3430 if (user
&& !capable(CAP_SYS_NICE
)) {
3431 if (fair_policy(policy
)) {
3432 if (attr
->sched_nice
< task_nice(p
) &&
3433 !can_nice(p
, attr
->sched_nice
))
3437 if (rt_policy(policy
)) {
3438 unsigned long rlim_rtprio
=
3439 task_rlimit(p
, RLIMIT_RTPRIO
);
3441 /* can't set/change the rt policy */
3442 if (policy
!= p
->policy
&& !rlim_rtprio
)
3445 /* can't increase priority */
3446 if (attr
->sched_priority
> p
->rt_priority
&&
3447 attr
->sched_priority
> rlim_rtprio
)
3452 * Can't set/change SCHED_DEADLINE policy at all for now
3453 * (safest behavior); in the future we would like to allow
3454 * unprivileged DL tasks to increase their relative deadline
3455 * or reduce their runtime (both ways reducing utilization)
3457 if (dl_policy(policy
))
3461 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3462 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3464 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
) {
3465 if (!can_nice(p
, task_nice(p
)))
3469 /* can't change other user's priorities */
3470 if (!check_same_owner(p
))
3473 /* Normal users shall not reset the sched_reset_on_fork flag */
3474 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3479 retval
= security_task_setscheduler(p
);
3485 * make sure no PI-waiters arrive (or leave) while we are
3486 * changing the priority of the task:
3488 * To be able to change p->policy safely, the appropriate
3489 * runqueue lock must be held.
3491 rq
= task_rq_lock(p
, &flags
);
3494 * Changing the policy of the stop threads its a very bad idea
3496 if (p
== rq
->stop
) {
3497 task_rq_unlock(rq
, p
, &flags
);
3502 * If not changing anything there's no need to proceed further,
3503 * but store a possible modification of reset_on_fork.
3505 if (unlikely(policy
== p
->policy
)) {
3506 if (fair_policy(policy
) && attr
->sched_nice
!= task_nice(p
))
3508 if (rt_policy(policy
) && attr
->sched_priority
!= p
->rt_priority
)
3510 if (dl_policy(policy
) && dl_param_changed(p
, attr
))
3513 p
->sched_reset_on_fork
= reset_on_fork
;
3514 task_rq_unlock(rq
, p
, &flags
);
3520 #ifdef CONFIG_RT_GROUP_SCHED
3522 * Do not allow realtime tasks into groups that have no runtime
3525 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
3526 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
3527 !task_group_is_autogroup(task_group(p
))) {
3528 task_rq_unlock(rq
, p
, &flags
);
3533 if (dl_bandwidth_enabled() && dl_policy(policy
)) {
3534 cpumask_t
*span
= rq
->rd
->span
;
3537 * Don't allow tasks with an affinity mask smaller than
3538 * the entire root_domain to become SCHED_DEADLINE. We
3539 * will also fail if there's no bandwidth available.
3541 if (!cpumask_subset(span
, &p
->cpus_allowed
) ||
3542 rq
->rd
->dl_bw
.bw
== 0) {
3543 task_rq_unlock(rq
, p
, &flags
);
3550 /* recheck policy now with rq lock held */
3551 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3552 policy
= oldpolicy
= -1;
3553 task_rq_unlock(rq
, p
, &flags
);
3558 * If setscheduling to SCHED_DEADLINE (or changing the parameters
3559 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
3562 if ((dl_policy(policy
) || dl_task(p
)) && dl_overflow(p
, policy
, attr
)) {
3563 task_rq_unlock(rq
, p
, &flags
);
3567 p
->sched_reset_on_fork
= reset_on_fork
;
3571 * Special case for priority boosted tasks.
3573 * If the new priority is lower or equal (user space view)
3574 * than the current (boosted) priority, we just store the new
3575 * normal parameters and do not touch the scheduler class and
3576 * the runqueue. This will be done when the task deboost
3579 if (rt_mutex_check_prio(p
, newprio
)) {
3580 __setscheduler_params(p
, attr
);
3581 task_rq_unlock(rq
, p
, &flags
);
3585 queued
= task_on_rq_queued(p
);
3586 running
= task_current(rq
, p
);
3588 dequeue_task(rq
, p
, 0);
3590 put_prev_task(rq
, p
);
3592 prev_class
= p
->sched_class
;
3593 __setscheduler(rq
, p
, attr
);
3596 p
->sched_class
->set_curr_task(rq
);
3599 * We enqueue to tail when the priority of a task is
3600 * increased (user space view).
3602 enqueue_task(rq
, p
, oldprio
<= p
->prio
? ENQUEUE_HEAD
: 0);
3605 check_class_changed(rq
, p
, prev_class
, oldprio
);
3606 task_rq_unlock(rq
, p
, &flags
);
3608 rt_mutex_adjust_pi(p
);
3613 static int _sched_setscheduler(struct task_struct
*p
, int policy
,
3614 const struct sched_param
*param
, bool check
)
3616 struct sched_attr attr
= {
3617 .sched_policy
= policy
,
3618 .sched_priority
= param
->sched_priority
,
3619 .sched_nice
= PRIO_TO_NICE(p
->static_prio
),
3622 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
3623 if ((policy
!= SETPARAM_POLICY
) && (policy
& SCHED_RESET_ON_FORK
)) {
3624 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
3625 policy
&= ~SCHED_RESET_ON_FORK
;
3626 attr
.sched_policy
= policy
;
3629 return __sched_setscheduler(p
, &attr
, check
);
3632 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3633 * @p: the task in question.
3634 * @policy: new policy.
3635 * @param: structure containing the new RT priority.
3637 * Return: 0 on success. An error code otherwise.
3639 * NOTE that the task may be already dead.
3641 int sched_setscheduler(struct task_struct
*p
, int policy
,
3642 const struct sched_param
*param
)
3644 return _sched_setscheduler(p
, policy
, param
, true);
3646 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3648 int sched_setattr(struct task_struct
*p
, const struct sched_attr
*attr
)
3650 return __sched_setscheduler(p
, attr
, true);
3652 EXPORT_SYMBOL_GPL(sched_setattr
);
3655 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3656 * @p: the task in question.
3657 * @policy: new policy.
3658 * @param: structure containing the new RT priority.
3660 * Just like sched_setscheduler, only don't bother checking if the
3661 * current context has permission. For example, this is needed in
3662 * stop_machine(): we create temporary high priority worker threads,
3663 * but our caller might not have that capability.
3665 * Return: 0 on success. An error code otherwise.
3667 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
3668 const struct sched_param
*param
)
3670 return _sched_setscheduler(p
, policy
, param
, false);
3674 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3676 struct sched_param lparam
;
3677 struct task_struct
*p
;
3680 if (!param
|| pid
< 0)
3682 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3687 p
= find_process_by_pid(pid
);
3689 retval
= sched_setscheduler(p
, policy
, &lparam
);
3696 * Mimics kernel/events/core.c perf_copy_attr().
3698 static int sched_copy_attr(struct sched_attr __user
*uattr
,
3699 struct sched_attr
*attr
)
3704 if (!access_ok(VERIFY_WRITE
, uattr
, SCHED_ATTR_SIZE_VER0
))
3708 * zero the full structure, so that a short copy will be nice.
3710 memset(attr
, 0, sizeof(*attr
));
3712 ret
= get_user(size
, &uattr
->size
);
3716 if (size
> PAGE_SIZE
) /* silly large */
3719 if (!size
) /* abi compat */
3720 size
= SCHED_ATTR_SIZE_VER0
;
3722 if (size
< SCHED_ATTR_SIZE_VER0
)
3726 * If we're handed a bigger struct than we know of,
3727 * ensure all the unknown bits are 0 - i.e. new
3728 * user-space does not rely on any kernel feature
3729 * extensions we dont know about yet.
3731 if (size
> sizeof(*attr
)) {
3732 unsigned char __user
*addr
;
3733 unsigned char __user
*end
;
3736 addr
= (void __user
*)uattr
+ sizeof(*attr
);
3737 end
= (void __user
*)uattr
+ size
;
3739 for (; addr
< end
; addr
++) {
3740 ret
= get_user(val
, addr
);
3746 size
= sizeof(*attr
);
3749 ret
= copy_from_user(attr
, uattr
, size
);
3754 * XXX: do we want to be lenient like existing syscalls; or do we want
3755 * to be strict and return an error on out-of-bounds values?
3757 attr
->sched_nice
= clamp(attr
->sched_nice
, MIN_NICE
, MAX_NICE
);
3762 put_user(sizeof(*attr
), &uattr
->size
);
3767 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3768 * @pid: the pid in question.
3769 * @policy: new policy.
3770 * @param: structure containing the new RT priority.
3772 * Return: 0 on success. An error code otherwise.
3774 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
3775 struct sched_param __user
*, param
)
3777 /* negative values for policy are not valid */
3781 return do_sched_setscheduler(pid
, policy
, param
);
3785 * sys_sched_setparam - set/change the RT priority of a thread
3786 * @pid: the pid in question.
3787 * @param: structure containing the new RT priority.
3789 * Return: 0 on success. An error code otherwise.
3791 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
3793 return do_sched_setscheduler(pid
, SETPARAM_POLICY
, param
);
3797 * sys_sched_setattr - same as above, but with extended sched_attr
3798 * @pid: the pid in question.
3799 * @uattr: structure containing the extended parameters.
3800 * @flags: for future extension.
3802 SYSCALL_DEFINE3(sched_setattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
3803 unsigned int, flags
)
3805 struct sched_attr attr
;
3806 struct task_struct
*p
;
3809 if (!uattr
|| pid
< 0 || flags
)
3812 retval
= sched_copy_attr(uattr
, &attr
);
3816 if ((int)attr
.sched_policy
< 0)
3821 p
= find_process_by_pid(pid
);
3823 retval
= sched_setattr(p
, &attr
);
3830 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3831 * @pid: the pid in question.
3833 * Return: On success, the policy of the thread. Otherwise, a negative error
3836 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
3838 struct task_struct
*p
;
3846 p
= find_process_by_pid(pid
);
3848 retval
= security_task_getscheduler(p
);
3851 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
3858 * sys_sched_getparam - get the RT priority of a thread
3859 * @pid: the pid in question.
3860 * @param: structure containing the RT priority.
3862 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
3865 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
3867 struct sched_param lp
= { .sched_priority
= 0 };
3868 struct task_struct
*p
;
3871 if (!param
|| pid
< 0)
3875 p
= find_process_by_pid(pid
);
3880 retval
= security_task_getscheduler(p
);
3884 if (task_has_rt_policy(p
))
3885 lp
.sched_priority
= p
->rt_priority
;
3889 * This one might sleep, we cannot do it with a spinlock held ...
3891 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3900 static int sched_read_attr(struct sched_attr __user
*uattr
,
3901 struct sched_attr
*attr
,
3906 if (!access_ok(VERIFY_WRITE
, uattr
, usize
))
3910 * If we're handed a smaller struct than we know of,
3911 * ensure all the unknown bits are 0 - i.e. old
3912 * user-space does not get uncomplete information.
3914 if (usize
< sizeof(*attr
)) {
3915 unsigned char *addr
;
3918 addr
= (void *)attr
+ usize
;
3919 end
= (void *)attr
+ sizeof(*attr
);
3921 for (; addr
< end
; addr
++) {
3929 ret
= copy_to_user(uattr
, attr
, attr
->size
);
3937 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
3938 * @pid: the pid in question.
3939 * @uattr: structure containing the extended parameters.
3940 * @size: sizeof(attr) for fwd/bwd comp.
3941 * @flags: for future extension.
3943 SYSCALL_DEFINE4(sched_getattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
3944 unsigned int, size
, unsigned int, flags
)
3946 struct sched_attr attr
= {
3947 .size
= sizeof(struct sched_attr
),
3949 struct task_struct
*p
;
3952 if (!uattr
|| pid
< 0 || size
> PAGE_SIZE
||
3953 size
< SCHED_ATTR_SIZE_VER0
|| flags
)
3957 p
= find_process_by_pid(pid
);
3962 retval
= security_task_getscheduler(p
);
3966 attr
.sched_policy
= p
->policy
;
3967 if (p
->sched_reset_on_fork
)
3968 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
3969 if (task_has_dl_policy(p
))
3970 __getparam_dl(p
, &attr
);
3971 else if (task_has_rt_policy(p
))
3972 attr
.sched_priority
= p
->rt_priority
;
3974 attr
.sched_nice
= task_nice(p
);
3978 retval
= sched_read_attr(uattr
, &attr
, size
);
3986 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
3988 cpumask_var_t cpus_allowed
, new_mask
;
3989 struct task_struct
*p
;
3994 p
= find_process_by_pid(pid
);
4000 /* Prevent p going away */
4004 if (p
->flags
& PF_NO_SETAFFINITY
) {
4008 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4012 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4014 goto out_free_cpus_allowed
;
4017 if (!check_same_owner(p
)) {
4019 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4021 goto out_free_new_mask
;
4026 retval
= security_task_setscheduler(p
);
4028 goto out_free_new_mask
;
4031 cpuset_cpus_allowed(p
, cpus_allowed
);
4032 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4035 * Since bandwidth control happens on root_domain basis,
4036 * if admission test is enabled, we only admit -deadline
4037 * tasks allowed to run on all the CPUs in the task's
4041 if (task_has_dl_policy(p
) && dl_bandwidth_enabled()) {
4043 if (!cpumask_subset(task_rq(p
)->rd
->span
, new_mask
)) {
4046 goto out_free_new_mask
;
4052 retval
= set_cpus_allowed_ptr(p
, new_mask
);
4055 cpuset_cpus_allowed(p
, cpus_allowed
);
4056 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4058 * We must have raced with a concurrent cpuset
4059 * update. Just reset the cpus_allowed to the
4060 * cpuset's cpus_allowed
4062 cpumask_copy(new_mask
, cpus_allowed
);
4067 free_cpumask_var(new_mask
);
4068 out_free_cpus_allowed
:
4069 free_cpumask_var(cpus_allowed
);
4075 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4076 struct cpumask
*new_mask
)
4078 if (len
< cpumask_size())
4079 cpumask_clear(new_mask
);
4080 else if (len
> cpumask_size())
4081 len
= cpumask_size();
4083 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4087 * sys_sched_setaffinity - set the cpu affinity of a process
4088 * @pid: pid of the process
4089 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4090 * @user_mask_ptr: user-space pointer to the new cpu mask
4092 * Return: 0 on success. An error code otherwise.
4094 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4095 unsigned long __user
*, user_mask_ptr
)
4097 cpumask_var_t new_mask
;
4100 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4103 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4105 retval
= sched_setaffinity(pid
, new_mask
);
4106 free_cpumask_var(new_mask
);
4110 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4112 struct task_struct
*p
;
4113 unsigned long flags
;
4119 p
= find_process_by_pid(pid
);
4123 retval
= security_task_getscheduler(p
);
4127 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4128 cpumask_and(mask
, &p
->cpus_allowed
, cpu_active_mask
);
4129 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4138 * sys_sched_getaffinity - get the cpu affinity of a process
4139 * @pid: pid of the process
4140 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4141 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4143 * Return: 0 on success. An error code otherwise.
4145 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4146 unsigned long __user
*, user_mask_ptr
)
4151 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4153 if (len
& (sizeof(unsigned long)-1))
4156 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4159 ret
= sched_getaffinity(pid
, mask
);
4161 size_t retlen
= min_t(size_t, len
, cpumask_size());
4163 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4168 free_cpumask_var(mask
);
4174 * sys_sched_yield - yield the current processor to other threads.
4176 * This function yields the current CPU to other tasks. If there are no
4177 * other threads running on this CPU then this function will return.
4181 SYSCALL_DEFINE0(sched_yield
)
4183 struct rq
*rq
= this_rq_lock();
4185 schedstat_inc(rq
, yld_count
);
4186 current
->sched_class
->yield_task(rq
);
4189 * Since we are going to call schedule() anyway, there's
4190 * no need to preempt or enable interrupts:
4192 __release(rq
->lock
);
4193 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4194 do_raw_spin_unlock(&rq
->lock
);
4195 sched_preempt_enable_no_resched();
4202 int __sched
_cond_resched(void)
4204 if (should_resched()) {
4205 preempt_schedule_common();
4210 EXPORT_SYMBOL(_cond_resched
);
4213 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4214 * call schedule, and on return reacquire the lock.
4216 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4217 * operations here to prevent schedule() from being called twice (once via
4218 * spin_unlock(), once by hand).
4220 int __cond_resched_lock(spinlock_t
*lock
)
4222 int resched
= should_resched();
4225 lockdep_assert_held(lock
);
4227 if (spin_needbreak(lock
) || resched
) {
4230 preempt_schedule_common();
4238 EXPORT_SYMBOL(__cond_resched_lock
);
4240 int __sched
__cond_resched_softirq(void)
4242 BUG_ON(!in_softirq());
4244 if (should_resched()) {
4246 preempt_schedule_common();
4252 EXPORT_SYMBOL(__cond_resched_softirq
);
4255 * yield - yield the current processor to other threads.
4257 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4259 * The scheduler is at all times free to pick the calling task as the most
4260 * eligible task to run, if removing the yield() call from your code breaks
4261 * it, its already broken.
4263 * Typical broken usage is:
4268 * where one assumes that yield() will let 'the other' process run that will
4269 * make event true. If the current task is a SCHED_FIFO task that will never
4270 * happen. Never use yield() as a progress guarantee!!
4272 * If you want to use yield() to wait for something, use wait_event().
4273 * If you want to use yield() to be 'nice' for others, use cond_resched().
4274 * If you still want to use yield(), do not!
4276 void __sched
yield(void)
4278 set_current_state(TASK_RUNNING
);
4281 EXPORT_SYMBOL(yield
);
4284 * yield_to - yield the current processor to another thread in
4285 * your thread group, or accelerate that thread toward the
4286 * processor it's on.
4288 * @preempt: whether task preemption is allowed or not
4290 * It's the caller's job to ensure that the target task struct
4291 * can't go away on us before we can do any checks.
4294 * true (>0) if we indeed boosted the target task.
4295 * false (0) if we failed to boost the target.
4296 * -ESRCH if there's no task to yield to.
4298 int __sched
yield_to(struct task_struct
*p
, bool preempt
)
4300 struct task_struct
*curr
= current
;
4301 struct rq
*rq
, *p_rq
;
4302 unsigned long flags
;
4305 local_irq_save(flags
);
4311 * If we're the only runnable task on the rq and target rq also
4312 * has only one task, there's absolutely no point in yielding.
4314 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4319 double_rq_lock(rq
, p_rq
);
4320 if (task_rq(p
) != p_rq
) {
4321 double_rq_unlock(rq
, p_rq
);
4325 if (!curr
->sched_class
->yield_to_task
)
4328 if (curr
->sched_class
!= p
->sched_class
)
4331 if (task_running(p_rq
, p
) || p
->state
)
4334 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4336 schedstat_inc(rq
, yld_count
);
4338 * Make p's CPU reschedule; pick_next_entity takes care of
4341 if (preempt
&& rq
!= p_rq
)
4346 double_rq_unlock(rq
, p_rq
);
4348 local_irq_restore(flags
);
4355 EXPORT_SYMBOL_GPL(yield_to
);
4358 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4359 * that process accounting knows that this is a task in IO wait state.
4361 long __sched
io_schedule_timeout(long timeout
)
4363 int old_iowait
= current
->in_iowait
;
4367 current
->in_iowait
= 1;
4369 blk_schedule_flush_plug(current
);
4371 blk_flush_plug(current
);
4373 delayacct_blkio_start();
4375 atomic_inc(&rq
->nr_iowait
);
4376 ret
= schedule_timeout(timeout
);
4377 current
->in_iowait
= old_iowait
;
4378 atomic_dec(&rq
->nr_iowait
);
4379 delayacct_blkio_end();
4383 EXPORT_SYMBOL(io_schedule_timeout
);
4386 * sys_sched_get_priority_max - return maximum RT priority.
4387 * @policy: scheduling class.
4389 * Return: On success, this syscall returns the maximum
4390 * rt_priority that can be used by a given scheduling class.
4391 * On failure, a negative error code is returned.
4393 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
4400 ret
= MAX_USER_RT_PRIO
-1;
4402 case SCHED_DEADLINE
:
4413 * sys_sched_get_priority_min - return minimum RT priority.
4414 * @policy: scheduling class.
4416 * Return: On success, this syscall returns the minimum
4417 * rt_priority that can be used by a given scheduling class.
4418 * On failure, a negative error code is returned.
4420 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
4429 case SCHED_DEADLINE
:
4439 * sys_sched_rr_get_interval - return the default timeslice of a process.
4440 * @pid: pid of the process.
4441 * @interval: userspace pointer to the timeslice value.
4443 * this syscall writes the default timeslice value of a given process
4444 * into the user-space timespec buffer. A value of '0' means infinity.
4446 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4449 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
4450 struct timespec __user
*, interval
)
4452 struct task_struct
*p
;
4453 unsigned int time_slice
;
4454 unsigned long flags
;
4464 p
= find_process_by_pid(pid
);
4468 retval
= security_task_getscheduler(p
);
4472 rq
= task_rq_lock(p
, &flags
);
4474 if (p
->sched_class
->get_rr_interval
)
4475 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
4476 task_rq_unlock(rq
, p
, &flags
);
4479 jiffies_to_timespec(time_slice
, &t
);
4480 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4488 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
4490 void sched_show_task(struct task_struct
*p
)
4492 unsigned long free
= 0;
4494 unsigned long state
= p
->state
;
4497 state
= __ffs(state
) + 1;
4498 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
4499 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4500 #if BITS_PER_LONG == 32
4501 if (state
== TASK_RUNNING
)
4502 printk(KERN_CONT
" running ");
4504 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4506 if (state
== TASK_RUNNING
)
4507 printk(KERN_CONT
" running task ");
4509 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4511 #ifdef CONFIG_DEBUG_STACK_USAGE
4512 free
= stack_not_used(p
);
4517 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
4519 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
4520 task_pid_nr(p
), ppid
,
4521 (unsigned long)task_thread_info(p
)->flags
);
4523 print_worker_info(KERN_INFO
, p
);
4524 show_stack(p
, NULL
);
4527 void show_state_filter(unsigned long state_filter
)
4529 struct task_struct
*g
, *p
;
4531 #if BITS_PER_LONG == 32
4533 " task PC stack pid father\n");
4536 " task PC stack pid father\n");
4539 for_each_process_thread(g
, p
) {
4541 * reset the NMI-timeout, listing all files on a slow
4542 * console might take a lot of time:
4544 touch_nmi_watchdog();
4545 if (!state_filter
|| (p
->state
& state_filter
))
4549 touch_all_softlockup_watchdogs();
4551 #ifdef CONFIG_SCHED_DEBUG
4552 sysrq_sched_debug_show();
4556 * Only show locks if all tasks are dumped:
4559 debug_show_all_locks();
4562 void init_idle_bootup_task(struct task_struct
*idle
)
4564 idle
->sched_class
= &idle_sched_class
;
4568 * init_idle - set up an idle thread for a given CPU
4569 * @idle: task in question
4570 * @cpu: cpu the idle task belongs to
4572 * NOTE: this function does not set the idle thread's NEED_RESCHED
4573 * flag, to make booting more robust.
4575 void init_idle(struct task_struct
*idle
, int cpu
)
4577 struct rq
*rq
= cpu_rq(cpu
);
4578 unsigned long flags
;
4580 raw_spin_lock_irqsave(&rq
->lock
, flags
);
4582 __sched_fork(0, idle
);
4583 idle
->state
= TASK_RUNNING
;
4584 idle
->se
.exec_start
= sched_clock();
4586 do_set_cpus_allowed(idle
, cpumask_of(cpu
));
4588 * We're having a chicken and egg problem, even though we are
4589 * holding rq->lock, the cpu isn't yet set to this cpu so the
4590 * lockdep check in task_group() will fail.
4592 * Similar case to sched_fork(). / Alternatively we could
4593 * use task_rq_lock() here and obtain the other rq->lock.
4598 __set_task_cpu(idle
, cpu
);
4601 rq
->curr
= rq
->idle
= idle
;
4602 idle
->on_rq
= TASK_ON_RQ_QUEUED
;
4603 #if defined(CONFIG_SMP)
4606 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
4608 /* Set the preempt count _outside_ the spinlocks! */
4609 init_idle_preempt_count(idle
, cpu
);
4612 * The idle tasks have their own, simple scheduling class:
4614 idle
->sched_class
= &idle_sched_class
;
4615 ftrace_graph_init_idle_task(idle
, cpu
);
4616 vtime_init_idle(idle
, cpu
);
4617 #if defined(CONFIG_SMP)
4618 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
4622 int cpuset_cpumask_can_shrink(const struct cpumask
*cur
,
4623 const struct cpumask
*trial
)
4625 int ret
= 1, trial_cpus
;
4626 struct dl_bw
*cur_dl_b
;
4627 unsigned long flags
;
4629 if (!cpumask_weight(cur
))
4632 rcu_read_lock_sched();
4633 cur_dl_b
= dl_bw_of(cpumask_any(cur
));
4634 trial_cpus
= cpumask_weight(trial
);
4636 raw_spin_lock_irqsave(&cur_dl_b
->lock
, flags
);
4637 if (cur_dl_b
->bw
!= -1 &&
4638 cur_dl_b
->bw
* trial_cpus
< cur_dl_b
->total_bw
)
4640 raw_spin_unlock_irqrestore(&cur_dl_b
->lock
, flags
);
4641 rcu_read_unlock_sched();
4646 int task_can_attach(struct task_struct
*p
,
4647 const struct cpumask
*cs_cpus_allowed
)
4652 * Kthreads which disallow setaffinity shouldn't be moved
4653 * to a new cpuset; we don't want to change their cpu
4654 * affinity and isolating such threads by their set of
4655 * allowed nodes is unnecessary. Thus, cpusets are not
4656 * applicable for such threads. This prevents checking for
4657 * success of set_cpus_allowed_ptr() on all attached tasks
4658 * before cpus_allowed may be changed.
4660 if (p
->flags
& PF_NO_SETAFFINITY
) {
4666 if (dl_task(p
) && !cpumask_intersects(task_rq(p
)->rd
->span
,
4668 unsigned int dest_cpu
= cpumask_any_and(cpu_active_mask
,
4673 unsigned long flags
;
4675 rcu_read_lock_sched();
4676 dl_b
= dl_bw_of(dest_cpu
);
4677 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
4678 cpus
= dl_bw_cpus(dest_cpu
);
4679 overflow
= __dl_overflow(dl_b
, cpus
, 0, p
->dl
.dl_bw
);
4684 * We reserve space for this task in the destination
4685 * root_domain, as we can't fail after this point.
4686 * We will free resources in the source root_domain
4687 * later on (see set_cpus_allowed_dl()).
4689 __dl_add(dl_b
, p
->dl
.dl_bw
);
4691 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
4692 rcu_read_unlock_sched();
4702 * move_queued_task - move a queued task to new rq.
4704 * Returns (locked) new rq. Old rq's lock is released.
4706 static struct rq
*move_queued_task(struct task_struct
*p
, int new_cpu
)
4708 struct rq
*rq
= task_rq(p
);
4710 lockdep_assert_held(&rq
->lock
);
4712 dequeue_task(rq
, p
, 0);
4713 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
4714 set_task_cpu(p
, new_cpu
);
4715 raw_spin_unlock(&rq
->lock
);
4717 rq
= cpu_rq(new_cpu
);
4719 raw_spin_lock(&rq
->lock
);
4720 BUG_ON(task_cpu(p
) != new_cpu
);
4721 p
->on_rq
= TASK_ON_RQ_QUEUED
;
4722 enqueue_task(rq
, p
, 0);
4723 check_preempt_curr(rq
, p
, 0);
4728 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
4730 if (p
->sched_class
->set_cpus_allowed
)
4731 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
4733 cpumask_copy(&p
->cpus_allowed
, new_mask
);
4734 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
4738 * This is how migration works:
4740 * 1) we invoke migration_cpu_stop() on the target CPU using
4742 * 2) stopper starts to run (implicitly forcing the migrated thread
4744 * 3) it checks whether the migrated task is still in the wrong runqueue.
4745 * 4) if it's in the wrong runqueue then the migration thread removes
4746 * it and puts it into the right queue.
4747 * 5) stopper completes and stop_one_cpu() returns and the migration
4752 * Change a given task's CPU affinity. Migrate the thread to a
4753 * proper CPU and schedule it away if the CPU it's executing on
4754 * is removed from the allowed bitmask.
4756 * NOTE: the caller must have a valid reference to the task, the
4757 * task must not exit() & deallocate itself prematurely. The
4758 * call is not atomic; no spinlocks may be held.
4760 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
4762 unsigned long flags
;
4764 unsigned int dest_cpu
;
4767 rq
= task_rq_lock(p
, &flags
);
4769 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
4772 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
4777 do_set_cpus_allowed(p
, new_mask
);
4779 /* Can the task run on the task's current CPU? If so, we're done */
4780 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
4783 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
4784 if (task_running(rq
, p
) || p
->state
== TASK_WAKING
) {
4785 struct migration_arg arg
= { p
, dest_cpu
};
4786 /* Need help from migration thread: drop lock and wait. */
4787 task_rq_unlock(rq
, p
, &flags
);
4788 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
4789 tlb_migrate_finish(p
->mm
);
4791 } else if (task_on_rq_queued(p
))
4792 rq
= move_queued_task(p
, dest_cpu
);
4794 task_rq_unlock(rq
, p
, &flags
);
4798 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
4801 * Move (not current) task off this cpu, onto dest cpu. We're doing
4802 * this because either it can't run here any more (set_cpus_allowed()
4803 * away from this CPU, or CPU going down), or because we're
4804 * attempting to rebalance this task on exec (sched_exec).
4806 * So we race with normal scheduler movements, but that's OK, as long
4807 * as the task is no longer on this CPU.
4809 * Returns non-zero if task was successfully migrated.
4811 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4816 if (unlikely(!cpu_active(dest_cpu
)))
4819 rq
= cpu_rq(src_cpu
);
4821 raw_spin_lock(&p
->pi_lock
);
4822 raw_spin_lock(&rq
->lock
);
4823 /* Already moved. */
4824 if (task_cpu(p
) != src_cpu
)
4827 /* Affinity changed (again). */
4828 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
4832 * If we're not on a rq, the next wake-up will ensure we're
4835 if (task_on_rq_queued(p
))
4836 rq
= move_queued_task(p
, dest_cpu
);
4840 raw_spin_unlock(&rq
->lock
);
4841 raw_spin_unlock(&p
->pi_lock
);
4845 #ifdef CONFIG_NUMA_BALANCING
4846 /* Migrate current task p to target_cpu */
4847 int migrate_task_to(struct task_struct
*p
, int target_cpu
)
4849 struct migration_arg arg
= { p
, target_cpu
};
4850 int curr_cpu
= task_cpu(p
);
4852 if (curr_cpu
== target_cpu
)
4855 if (!cpumask_test_cpu(target_cpu
, tsk_cpus_allowed(p
)))
4858 /* TODO: This is not properly updating schedstats */
4860 trace_sched_move_numa(p
, curr_cpu
, target_cpu
);
4861 return stop_one_cpu(curr_cpu
, migration_cpu_stop
, &arg
);
4865 * Requeue a task on a given node and accurately track the number of NUMA
4866 * tasks on the runqueues
4868 void sched_setnuma(struct task_struct
*p
, int nid
)
4871 unsigned long flags
;
4872 bool queued
, running
;
4874 rq
= task_rq_lock(p
, &flags
);
4875 queued
= task_on_rq_queued(p
);
4876 running
= task_current(rq
, p
);
4879 dequeue_task(rq
, p
, 0);
4881 put_prev_task(rq
, p
);
4883 p
->numa_preferred_nid
= nid
;
4886 p
->sched_class
->set_curr_task(rq
);
4888 enqueue_task(rq
, p
, 0);
4889 task_rq_unlock(rq
, p
, &flags
);
4894 * migration_cpu_stop - this will be executed by a highprio stopper thread
4895 * and performs thread migration by bumping thread off CPU then
4896 * 'pushing' onto another runqueue.
4898 static int migration_cpu_stop(void *data
)
4900 struct migration_arg
*arg
= data
;
4903 * The original target cpu might have gone down and we might
4904 * be on another cpu but it doesn't matter.
4906 local_irq_disable();
4908 * We need to explicitly wake pending tasks before running
4909 * __migrate_task() such that we will not miss enforcing cpus_allowed
4910 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
4912 sched_ttwu_pending();
4913 __migrate_task(arg
->task
, raw_smp_processor_id(), arg
->dest_cpu
);
4918 #ifdef CONFIG_HOTPLUG_CPU
4921 * Ensures that the idle task is using init_mm right before its cpu goes
4924 void idle_task_exit(void)
4926 struct mm_struct
*mm
= current
->active_mm
;
4928 BUG_ON(cpu_online(smp_processor_id()));
4930 if (mm
!= &init_mm
) {
4931 switch_mm(mm
, &init_mm
, current
);
4932 finish_arch_post_lock_switch();
4938 * Since this CPU is going 'away' for a while, fold any nr_active delta
4939 * we might have. Assumes we're called after migrate_tasks() so that the
4940 * nr_active count is stable.
4942 * Also see the comment "Global load-average calculations".
4944 static void calc_load_migrate(struct rq
*rq
)
4946 long delta
= calc_load_fold_active(rq
);
4948 atomic_long_add(delta
, &calc_load_tasks
);
4951 static void put_prev_task_fake(struct rq
*rq
, struct task_struct
*prev
)
4955 static const struct sched_class fake_sched_class
= {
4956 .put_prev_task
= put_prev_task_fake
,
4959 static struct task_struct fake_task
= {
4961 * Avoid pull_{rt,dl}_task()
4963 .prio
= MAX_PRIO
+ 1,
4964 .sched_class
= &fake_sched_class
,
4968 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4969 * try_to_wake_up()->select_task_rq().
4971 * Called with rq->lock held even though we'er in stop_machine() and
4972 * there's no concurrency possible, we hold the required locks anyway
4973 * because of lock validation efforts.
4975 static void migrate_tasks(unsigned int dead_cpu
)
4977 struct rq
*rq
= cpu_rq(dead_cpu
);
4978 struct task_struct
*next
, *stop
= rq
->stop
;
4982 * Fudge the rq selection such that the below task selection loop
4983 * doesn't get stuck on the currently eligible stop task.
4985 * We're currently inside stop_machine() and the rq is either stuck
4986 * in the stop_machine_cpu_stop() loop, or we're executing this code,
4987 * either way we should never end up calling schedule() until we're
4993 * put_prev_task() and pick_next_task() sched
4994 * class method both need to have an up-to-date
4995 * value of rq->clock[_task]
4997 update_rq_clock(rq
);
5001 * There's this thread running, bail when that's the only
5004 if (rq
->nr_running
== 1)
5007 next
= pick_next_task(rq
, &fake_task
);
5009 next
->sched_class
->put_prev_task(rq
, next
);
5011 /* Find suitable destination for @next, with force if needed. */
5012 dest_cpu
= select_fallback_rq(dead_cpu
, next
);
5013 raw_spin_unlock(&rq
->lock
);
5015 __migrate_task(next
, dead_cpu
, dest_cpu
);
5017 raw_spin_lock(&rq
->lock
);
5023 #endif /* CONFIG_HOTPLUG_CPU */
5025 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5027 static struct ctl_table sd_ctl_dir
[] = {
5029 .procname
= "sched_domain",
5035 static struct ctl_table sd_ctl_root
[] = {
5037 .procname
= "kernel",
5039 .child
= sd_ctl_dir
,
5044 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5046 struct ctl_table
*entry
=
5047 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5052 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5054 struct ctl_table
*entry
;
5057 * In the intermediate directories, both the child directory and
5058 * procname are dynamically allocated and could fail but the mode
5059 * will always be set. In the lowest directory the names are
5060 * static strings and all have proc handlers.
5062 for (entry
= *tablep
; entry
->mode
; entry
++) {
5064 sd_free_ctl_entry(&entry
->child
);
5065 if (entry
->proc_handler
== NULL
)
5066 kfree(entry
->procname
);
5073 static int min_load_idx
= 0;
5074 static int max_load_idx
= CPU_LOAD_IDX_MAX
-1;
5077 set_table_entry(struct ctl_table
*entry
,
5078 const char *procname
, void *data
, int maxlen
,
5079 umode_t mode
, proc_handler
*proc_handler
,
5082 entry
->procname
= procname
;
5084 entry
->maxlen
= maxlen
;
5086 entry
->proc_handler
= proc_handler
;
5089 entry
->extra1
= &min_load_idx
;
5090 entry
->extra2
= &max_load_idx
;
5094 static struct ctl_table
*
5095 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5097 struct ctl_table
*table
= sd_alloc_ctl_entry(14);
5102 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5103 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5104 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5105 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5106 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5107 sizeof(int), 0644, proc_dointvec_minmax
, true);
5108 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5109 sizeof(int), 0644, proc_dointvec_minmax
, true);
5110 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5111 sizeof(int), 0644, proc_dointvec_minmax
, true);
5112 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5113 sizeof(int), 0644, proc_dointvec_minmax
, true);
5114 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5115 sizeof(int), 0644, proc_dointvec_minmax
, true);
5116 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5117 sizeof(int), 0644, proc_dointvec_minmax
, false);
5118 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5119 sizeof(int), 0644, proc_dointvec_minmax
, false);
5120 set_table_entry(&table
[9], "cache_nice_tries",
5121 &sd
->cache_nice_tries
,
5122 sizeof(int), 0644, proc_dointvec_minmax
, false);
5123 set_table_entry(&table
[10], "flags", &sd
->flags
,
5124 sizeof(int), 0644, proc_dointvec_minmax
, false);
5125 set_table_entry(&table
[11], "max_newidle_lb_cost",
5126 &sd
->max_newidle_lb_cost
,
5127 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5128 set_table_entry(&table
[12], "name", sd
->name
,
5129 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
5130 /* &table[13] is terminator */
5135 static struct ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5137 struct ctl_table
*entry
, *table
;
5138 struct sched_domain
*sd
;
5139 int domain_num
= 0, i
;
5142 for_each_domain(cpu
, sd
)
5144 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5149 for_each_domain(cpu
, sd
) {
5150 snprintf(buf
, 32, "domain%d", i
);
5151 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5153 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5160 static struct ctl_table_header
*sd_sysctl_header
;
5161 static void register_sched_domain_sysctl(void)
5163 int i
, cpu_num
= num_possible_cpus();
5164 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5167 WARN_ON(sd_ctl_dir
[0].child
);
5168 sd_ctl_dir
[0].child
= entry
;
5173 for_each_possible_cpu(i
) {
5174 snprintf(buf
, 32, "cpu%d", i
);
5175 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5177 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5181 WARN_ON(sd_sysctl_header
);
5182 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5185 /* may be called multiple times per register */
5186 static void unregister_sched_domain_sysctl(void)
5188 if (sd_sysctl_header
)
5189 unregister_sysctl_table(sd_sysctl_header
);
5190 sd_sysctl_header
= NULL
;
5191 if (sd_ctl_dir
[0].child
)
5192 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5195 static void register_sched_domain_sysctl(void)
5198 static void unregister_sched_domain_sysctl(void)
5203 static void set_rq_online(struct rq
*rq
)
5206 const struct sched_class
*class;
5208 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5211 for_each_class(class) {
5212 if (class->rq_online
)
5213 class->rq_online(rq
);
5218 static void set_rq_offline(struct rq
*rq
)
5221 const struct sched_class
*class;
5223 for_each_class(class) {
5224 if (class->rq_offline
)
5225 class->rq_offline(rq
);
5228 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5234 * migration_call - callback that gets triggered when a CPU is added.
5235 * Here we can start up the necessary migration thread for the new CPU.
5238 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5240 int cpu
= (long)hcpu
;
5241 unsigned long flags
;
5242 struct rq
*rq
= cpu_rq(cpu
);
5244 switch (action
& ~CPU_TASKS_FROZEN
) {
5246 case CPU_UP_PREPARE
:
5247 rq
->calc_load_update
= calc_load_update
;
5251 /* Update our root-domain */
5252 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5254 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5258 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5261 #ifdef CONFIG_HOTPLUG_CPU
5263 sched_ttwu_pending();
5264 /* Update our root-domain */
5265 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5267 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5271 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
5272 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5276 calc_load_migrate(rq
);
5281 update_max_interval();
5287 * Register at high priority so that task migration (migrate_all_tasks)
5288 * happens before everything else. This has to be lower priority than
5289 * the notifier in the perf_event subsystem, though.
5291 static struct notifier_block migration_notifier
= {
5292 .notifier_call
= migration_call
,
5293 .priority
= CPU_PRI_MIGRATION
,
5296 static void __cpuinit
set_cpu_rq_start_time(void)
5298 int cpu
= smp_processor_id();
5299 struct rq
*rq
= cpu_rq(cpu
);
5300 rq
->age_stamp
= sched_clock_cpu(cpu
);
5303 static int sched_cpu_active(struct notifier_block
*nfb
,
5304 unsigned long action
, void *hcpu
)
5306 switch (action
& ~CPU_TASKS_FROZEN
) {
5308 set_cpu_rq_start_time();
5310 case CPU_DOWN_FAILED
:
5311 set_cpu_active((long)hcpu
, true);
5318 static int sched_cpu_inactive(struct notifier_block
*nfb
,
5319 unsigned long action
, void *hcpu
)
5321 unsigned long flags
;
5322 long cpu
= (long)hcpu
;
5325 switch (action
& ~CPU_TASKS_FROZEN
) {
5326 case CPU_DOWN_PREPARE
:
5327 set_cpu_active(cpu
, false);
5329 /* explicitly allow suspend */
5330 if (!(action
& CPU_TASKS_FROZEN
)) {
5334 rcu_read_lock_sched();
5335 dl_b
= dl_bw_of(cpu
);
5337 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
5338 cpus
= dl_bw_cpus(cpu
);
5339 overflow
= __dl_overflow(dl_b
, cpus
, 0, 0);
5340 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
5342 rcu_read_unlock_sched();
5345 return notifier_from_errno(-EBUSY
);
5353 static int __init
migration_init(void)
5355 void *cpu
= (void *)(long)smp_processor_id();
5358 /* Initialize migration for the boot CPU */
5359 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5360 BUG_ON(err
== NOTIFY_BAD
);
5361 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5362 register_cpu_notifier(&migration_notifier
);
5364 /* Register cpu active notifiers */
5365 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
5366 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
5370 early_initcall(migration_init
);
5375 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5377 #ifdef CONFIG_SCHED_DEBUG
5379 static __read_mostly
int sched_debug_enabled
;
5381 static int __init
sched_debug_setup(char *str
)
5383 sched_debug_enabled
= 1;
5387 early_param("sched_debug", sched_debug_setup
);
5389 static inline bool sched_debug(void)
5391 return sched_debug_enabled
;
5394 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5395 struct cpumask
*groupmask
)
5397 struct sched_group
*group
= sd
->groups
;
5399 cpumask_clear(groupmask
);
5401 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5403 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5404 printk("does not load-balance\n");
5406 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5411 printk(KERN_CONT
"span %*pbl level %s\n",
5412 cpumask_pr_args(sched_domain_span(sd
)), sd
->name
);
5414 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5415 printk(KERN_ERR
"ERROR: domain->span does not contain "
5418 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5419 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5423 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5427 printk(KERN_ERR
"ERROR: group is NULL\n");
5432 * Even though we initialize ->capacity to something semi-sane,
5433 * we leave capacity_orig unset. This allows us to detect if
5434 * domain iteration is still funny without causing /0 traps.
5436 if (!group
->sgc
->capacity_orig
) {
5437 printk(KERN_CONT
"\n");
5438 printk(KERN_ERR
"ERROR: domain->cpu_capacity not set\n");
5442 if (!cpumask_weight(sched_group_cpus(group
))) {
5443 printk(KERN_CONT
"\n");
5444 printk(KERN_ERR
"ERROR: empty group\n");
5448 if (!(sd
->flags
& SD_OVERLAP
) &&
5449 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5450 printk(KERN_CONT
"\n");
5451 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5455 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5457 printk(KERN_CONT
" %*pbl",
5458 cpumask_pr_args(sched_group_cpus(group
)));
5459 if (group
->sgc
->capacity
!= SCHED_CAPACITY_SCALE
) {
5460 printk(KERN_CONT
" (cpu_capacity = %d)",
5461 group
->sgc
->capacity
);
5464 group
= group
->next
;
5465 } while (group
!= sd
->groups
);
5466 printk(KERN_CONT
"\n");
5468 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5469 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5472 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5473 printk(KERN_ERR
"ERROR: parent span is not a superset "
5474 "of domain->span\n");
5478 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5482 if (!sched_debug_enabled
)
5486 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5490 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5493 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5501 #else /* !CONFIG_SCHED_DEBUG */
5502 # define sched_domain_debug(sd, cpu) do { } while (0)
5503 static inline bool sched_debug(void)
5507 #endif /* CONFIG_SCHED_DEBUG */
5509 static int sd_degenerate(struct sched_domain
*sd
)
5511 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5514 /* Following flags need at least 2 groups */
5515 if (sd
->flags
& (SD_LOAD_BALANCE
|
5516 SD_BALANCE_NEWIDLE
|
5519 SD_SHARE_CPUCAPACITY
|
5520 SD_SHARE_PKG_RESOURCES
|
5521 SD_SHARE_POWERDOMAIN
)) {
5522 if (sd
->groups
!= sd
->groups
->next
)
5526 /* Following flags don't use groups */
5527 if (sd
->flags
& (SD_WAKE_AFFINE
))
5534 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5536 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5538 if (sd_degenerate(parent
))
5541 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5544 /* Flags needing groups don't count if only 1 group in parent */
5545 if (parent
->groups
== parent
->groups
->next
) {
5546 pflags
&= ~(SD_LOAD_BALANCE
|
5547 SD_BALANCE_NEWIDLE
|
5550 SD_SHARE_CPUCAPACITY
|
5551 SD_SHARE_PKG_RESOURCES
|
5553 SD_SHARE_POWERDOMAIN
);
5554 if (nr_node_ids
== 1)
5555 pflags
&= ~SD_SERIALIZE
;
5557 if (~cflags
& pflags
)
5563 static void free_rootdomain(struct rcu_head
*rcu
)
5565 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5567 cpupri_cleanup(&rd
->cpupri
);
5568 cpudl_cleanup(&rd
->cpudl
);
5569 free_cpumask_var(rd
->dlo_mask
);
5570 free_cpumask_var(rd
->rto_mask
);
5571 free_cpumask_var(rd
->online
);
5572 free_cpumask_var(rd
->span
);
5576 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5578 struct root_domain
*old_rd
= NULL
;
5579 unsigned long flags
;
5581 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5586 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5589 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5592 * If we dont want to free the old_rd yet then
5593 * set old_rd to NULL to skip the freeing later
5596 if (!atomic_dec_and_test(&old_rd
->refcount
))
5600 atomic_inc(&rd
->refcount
);
5603 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5604 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5607 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5610 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5613 static int init_rootdomain(struct root_domain
*rd
)
5615 memset(rd
, 0, sizeof(*rd
));
5617 if (!alloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5619 if (!alloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5621 if (!alloc_cpumask_var(&rd
->dlo_mask
, GFP_KERNEL
))
5623 if (!alloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5626 init_dl_bw(&rd
->dl_bw
);
5627 if (cpudl_init(&rd
->cpudl
) != 0)
5630 if (cpupri_init(&rd
->cpupri
) != 0)
5635 free_cpumask_var(rd
->rto_mask
);
5637 free_cpumask_var(rd
->dlo_mask
);
5639 free_cpumask_var(rd
->online
);
5641 free_cpumask_var(rd
->span
);
5647 * By default the system creates a single root-domain with all cpus as
5648 * members (mimicking the global state we have today).
5650 struct root_domain def_root_domain
;
5652 static void init_defrootdomain(void)
5654 init_rootdomain(&def_root_domain
);
5656 atomic_set(&def_root_domain
.refcount
, 1);
5659 static struct root_domain
*alloc_rootdomain(void)
5661 struct root_domain
*rd
;
5663 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
5667 if (init_rootdomain(rd
) != 0) {
5675 static void free_sched_groups(struct sched_group
*sg
, int free_sgc
)
5677 struct sched_group
*tmp
, *first
;
5686 if (free_sgc
&& atomic_dec_and_test(&sg
->sgc
->ref
))
5691 } while (sg
!= first
);
5694 static void free_sched_domain(struct rcu_head
*rcu
)
5696 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
5699 * If its an overlapping domain it has private groups, iterate and
5702 if (sd
->flags
& SD_OVERLAP
) {
5703 free_sched_groups(sd
->groups
, 1);
5704 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
5705 kfree(sd
->groups
->sgc
);
5711 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
5713 call_rcu(&sd
->rcu
, free_sched_domain
);
5716 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
5718 for (; sd
; sd
= sd
->parent
)
5719 destroy_sched_domain(sd
, cpu
);
5723 * Keep a special pointer to the highest sched_domain that has
5724 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5725 * allows us to avoid some pointer chasing select_idle_sibling().
5727 * Also keep a unique ID per domain (we use the first cpu number in
5728 * the cpumask of the domain), this allows us to quickly tell if
5729 * two cpus are in the same cache domain, see cpus_share_cache().
5731 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
5732 DEFINE_PER_CPU(int, sd_llc_size
);
5733 DEFINE_PER_CPU(int, sd_llc_id
);
5734 DEFINE_PER_CPU(struct sched_domain
*, sd_numa
);
5735 DEFINE_PER_CPU(struct sched_domain
*, sd_busy
);
5736 DEFINE_PER_CPU(struct sched_domain
*, sd_asym
);
5738 static void update_top_cache_domain(int cpu
)
5740 struct sched_domain
*sd
;
5741 struct sched_domain
*busy_sd
= NULL
;
5745 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
5747 id
= cpumask_first(sched_domain_span(sd
));
5748 size
= cpumask_weight(sched_domain_span(sd
));
5749 busy_sd
= sd
->parent
; /* sd_busy */
5751 rcu_assign_pointer(per_cpu(sd_busy
, cpu
), busy_sd
);
5753 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
5754 per_cpu(sd_llc_size
, cpu
) = size
;
5755 per_cpu(sd_llc_id
, cpu
) = id
;
5757 sd
= lowest_flag_domain(cpu
, SD_NUMA
);
5758 rcu_assign_pointer(per_cpu(sd_numa
, cpu
), sd
);
5760 sd
= highest_flag_domain(cpu
, SD_ASYM_PACKING
);
5761 rcu_assign_pointer(per_cpu(sd_asym
, cpu
), sd
);
5765 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5766 * hold the hotplug lock.
5769 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
5771 struct rq
*rq
= cpu_rq(cpu
);
5772 struct sched_domain
*tmp
;
5774 /* Remove the sched domains which do not contribute to scheduling. */
5775 for (tmp
= sd
; tmp
; ) {
5776 struct sched_domain
*parent
= tmp
->parent
;
5780 if (sd_parent_degenerate(tmp
, parent
)) {
5781 tmp
->parent
= parent
->parent
;
5783 parent
->parent
->child
= tmp
;
5785 * Transfer SD_PREFER_SIBLING down in case of a
5786 * degenerate parent; the spans match for this
5787 * so the property transfers.
5789 if (parent
->flags
& SD_PREFER_SIBLING
)
5790 tmp
->flags
|= SD_PREFER_SIBLING
;
5791 destroy_sched_domain(parent
, cpu
);
5796 if (sd
&& sd_degenerate(sd
)) {
5799 destroy_sched_domain(tmp
, cpu
);
5804 sched_domain_debug(sd
, cpu
);
5806 rq_attach_root(rq
, rd
);
5808 rcu_assign_pointer(rq
->sd
, sd
);
5809 destroy_sched_domains(tmp
, cpu
);
5811 update_top_cache_domain(cpu
);
5814 /* cpus with isolated domains */
5815 static cpumask_var_t cpu_isolated_map
;
5817 /* Setup the mask of cpus configured for isolated domains */
5818 static int __init
isolated_cpu_setup(char *str
)
5820 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
5821 cpulist_parse(str
, cpu_isolated_map
);
5825 __setup("isolcpus=", isolated_cpu_setup
);
5828 struct sched_domain
** __percpu sd
;
5829 struct root_domain
*rd
;
5840 * Build an iteration mask that can exclude certain CPUs from the upwards
5843 * Asymmetric node setups can result in situations where the domain tree is of
5844 * unequal depth, make sure to skip domains that already cover the entire
5847 * In that case build_sched_domains() will have terminated the iteration early
5848 * and our sibling sd spans will be empty. Domains should always include the
5849 * cpu they're built on, so check that.
5852 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
5854 const struct cpumask
*span
= sched_domain_span(sd
);
5855 struct sd_data
*sdd
= sd
->private;
5856 struct sched_domain
*sibling
;
5859 for_each_cpu(i
, span
) {
5860 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5861 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5864 cpumask_set_cpu(i
, sched_group_mask(sg
));
5869 * Return the canonical balance cpu for this group, this is the first cpu
5870 * of this group that's also in the iteration mask.
5872 int group_balance_cpu(struct sched_group
*sg
)
5874 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
5878 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
5880 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
5881 const struct cpumask
*span
= sched_domain_span(sd
);
5882 struct cpumask
*covered
= sched_domains_tmpmask
;
5883 struct sd_data
*sdd
= sd
->private;
5884 struct sched_domain
*sibling
;
5887 cpumask_clear(covered
);
5889 for_each_cpu(i
, span
) {
5890 struct cpumask
*sg_span
;
5892 if (cpumask_test_cpu(i
, covered
))
5895 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
5897 /* See the comment near build_group_mask(). */
5898 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
5901 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
5902 GFP_KERNEL
, cpu_to_node(cpu
));
5907 sg_span
= sched_group_cpus(sg
);
5909 cpumask_copy(sg_span
, sched_domain_span(sibling
->child
));
5911 cpumask_set_cpu(i
, sg_span
);
5913 cpumask_or(covered
, covered
, sg_span
);
5915 sg
->sgc
= *per_cpu_ptr(sdd
->sgc
, i
);
5916 if (atomic_inc_return(&sg
->sgc
->ref
) == 1)
5917 build_group_mask(sd
, sg
);
5920 * Initialize sgc->capacity such that even if we mess up the
5921 * domains and no possible iteration will get us here, we won't
5924 sg
->sgc
->capacity
= SCHED_CAPACITY_SCALE
* cpumask_weight(sg_span
);
5925 sg
->sgc
->capacity_orig
= sg
->sgc
->capacity
;
5928 * Make sure the first group of this domain contains the
5929 * canonical balance cpu. Otherwise the sched_domain iteration
5930 * breaks. See update_sg_lb_stats().
5932 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
5933 group_balance_cpu(sg
) == cpu
)
5943 sd
->groups
= groups
;
5948 free_sched_groups(first
, 0);
5953 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
5955 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
5956 struct sched_domain
*child
= sd
->child
;
5959 cpu
= cpumask_first(sched_domain_span(child
));
5962 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
5963 (*sg
)->sgc
= *per_cpu_ptr(sdd
->sgc
, cpu
);
5964 atomic_set(&(*sg
)->sgc
->ref
, 1); /* for claim_allocations */
5971 * build_sched_groups will build a circular linked list of the groups
5972 * covered by the given span, and will set each group's ->cpumask correctly,
5973 * and ->cpu_capacity to 0.
5975 * Assumes the sched_domain tree is fully constructed
5978 build_sched_groups(struct sched_domain
*sd
, int cpu
)
5980 struct sched_group
*first
= NULL
, *last
= NULL
;
5981 struct sd_data
*sdd
= sd
->private;
5982 const struct cpumask
*span
= sched_domain_span(sd
);
5983 struct cpumask
*covered
;
5986 get_group(cpu
, sdd
, &sd
->groups
);
5987 atomic_inc(&sd
->groups
->ref
);
5989 if (cpu
!= cpumask_first(span
))
5992 lockdep_assert_held(&sched_domains_mutex
);
5993 covered
= sched_domains_tmpmask
;
5995 cpumask_clear(covered
);
5997 for_each_cpu(i
, span
) {
5998 struct sched_group
*sg
;
6001 if (cpumask_test_cpu(i
, covered
))
6004 group
= get_group(i
, sdd
, &sg
);
6005 cpumask_setall(sched_group_mask(sg
));
6007 for_each_cpu(j
, span
) {
6008 if (get_group(j
, sdd
, NULL
) != group
)
6011 cpumask_set_cpu(j
, covered
);
6012 cpumask_set_cpu(j
, sched_group_cpus(sg
));
6027 * Initialize sched groups cpu_capacity.
6029 * cpu_capacity indicates the capacity of sched group, which is used while
6030 * distributing the load between different sched groups in a sched domain.
6031 * Typically cpu_capacity for all the groups in a sched domain will be same
6032 * unless there are asymmetries in the topology. If there are asymmetries,
6033 * group having more cpu_capacity will pickup more load compared to the
6034 * group having less cpu_capacity.
6036 static void init_sched_groups_capacity(int cpu
, struct sched_domain
*sd
)
6038 struct sched_group
*sg
= sd
->groups
;
6043 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
6045 } while (sg
!= sd
->groups
);
6047 if (cpu
!= group_balance_cpu(sg
))
6050 update_group_capacity(sd
, cpu
);
6051 atomic_set(&sg
->sgc
->nr_busy_cpus
, sg
->group_weight
);
6055 * Initializers for schedule domains
6056 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6059 static int default_relax_domain_level
= -1;
6060 int sched_domain_level_max
;
6062 static int __init
setup_relax_domain_level(char *str
)
6064 if (kstrtoint(str
, 0, &default_relax_domain_level
))
6065 pr_warn("Unable to set relax_domain_level\n");
6069 __setup("relax_domain_level=", setup_relax_domain_level
);
6071 static void set_domain_attribute(struct sched_domain
*sd
,
6072 struct sched_domain_attr
*attr
)
6076 if (!attr
|| attr
->relax_domain_level
< 0) {
6077 if (default_relax_domain_level
< 0)
6080 request
= default_relax_domain_level
;
6082 request
= attr
->relax_domain_level
;
6083 if (request
< sd
->level
) {
6084 /* turn off idle balance on this domain */
6085 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6087 /* turn on idle balance on this domain */
6088 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6092 static void __sdt_free(const struct cpumask
*cpu_map
);
6093 static int __sdt_alloc(const struct cpumask
*cpu_map
);
6095 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
6096 const struct cpumask
*cpu_map
)
6100 if (!atomic_read(&d
->rd
->refcount
))
6101 free_rootdomain(&d
->rd
->rcu
); /* fall through */
6103 free_percpu(d
->sd
); /* fall through */
6105 __sdt_free(cpu_map
); /* fall through */
6111 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
6112 const struct cpumask
*cpu_map
)
6114 memset(d
, 0, sizeof(*d
));
6116 if (__sdt_alloc(cpu_map
))
6117 return sa_sd_storage
;
6118 d
->sd
= alloc_percpu(struct sched_domain
*);
6120 return sa_sd_storage
;
6121 d
->rd
= alloc_rootdomain();
6124 return sa_rootdomain
;
6128 * NULL the sd_data elements we've used to build the sched_domain and
6129 * sched_group structure so that the subsequent __free_domain_allocs()
6130 * will not free the data we're using.
6132 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6134 struct sd_data
*sdd
= sd
->private;
6136 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6137 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6139 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6140 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6142 if (atomic_read(&(*per_cpu_ptr(sdd
->sgc
, cpu
))->ref
))
6143 *per_cpu_ptr(sdd
->sgc
, cpu
) = NULL
;
6147 static int sched_domains_numa_levels
;
6148 enum numa_topology_type sched_numa_topology_type
;
6149 static int *sched_domains_numa_distance
;
6150 int sched_max_numa_distance
;
6151 static struct cpumask
***sched_domains_numa_masks
;
6152 static int sched_domains_curr_level
;
6156 * SD_flags allowed in topology descriptions.
6158 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6159 * SD_SHARE_PKG_RESOURCES - describes shared caches
6160 * SD_NUMA - describes NUMA topologies
6161 * SD_SHARE_POWERDOMAIN - describes shared power domain
6164 * SD_ASYM_PACKING - describes SMT quirks
6166 #define TOPOLOGY_SD_FLAGS \
6167 (SD_SHARE_CPUCAPACITY | \
6168 SD_SHARE_PKG_RESOURCES | \
6171 SD_SHARE_POWERDOMAIN)
6173 static struct sched_domain
*
6174 sd_init(struct sched_domain_topology_level
*tl
, int cpu
)
6176 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6177 int sd_weight
, sd_flags
= 0;
6181 * Ugly hack to pass state to sd_numa_mask()...
6183 sched_domains_curr_level
= tl
->numa_level
;
6186 sd_weight
= cpumask_weight(tl
->mask(cpu
));
6189 sd_flags
= (*tl
->sd_flags
)();
6190 if (WARN_ONCE(sd_flags
& ~TOPOLOGY_SD_FLAGS
,
6191 "wrong sd_flags in topology description\n"))
6192 sd_flags
&= ~TOPOLOGY_SD_FLAGS
;
6194 *sd
= (struct sched_domain
){
6195 .min_interval
= sd_weight
,
6196 .max_interval
= 2*sd_weight
,
6198 .imbalance_pct
= 125,
6200 .cache_nice_tries
= 0,
6207 .flags
= 1*SD_LOAD_BALANCE
6208 | 1*SD_BALANCE_NEWIDLE
6213 | 0*SD_SHARE_CPUCAPACITY
6214 | 0*SD_SHARE_PKG_RESOURCES
6216 | 0*SD_PREFER_SIBLING
6221 .last_balance
= jiffies
,
6222 .balance_interval
= sd_weight
,
6224 .max_newidle_lb_cost
= 0,
6225 .next_decay_max_lb_cost
= jiffies
,
6226 #ifdef CONFIG_SCHED_DEBUG
6232 * Convert topological properties into behaviour.
6235 if (sd
->flags
& SD_SHARE_CPUCAPACITY
) {
6236 sd
->imbalance_pct
= 110;
6237 sd
->smt_gain
= 1178; /* ~15% */
6239 } else if (sd
->flags
& SD_SHARE_PKG_RESOURCES
) {
6240 sd
->imbalance_pct
= 117;
6241 sd
->cache_nice_tries
= 1;
6245 } else if (sd
->flags
& SD_NUMA
) {
6246 sd
->cache_nice_tries
= 2;
6250 sd
->flags
|= SD_SERIALIZE
;
6251 if (sched_domains_numa_distance
[tl
->numa_level
] > RECLAIM_DISTANCE
) {
6252 sd
->flags
&= ~(SD_BALANCE_EXEC
|
6259 sd
->flags
|= SD_PREFER_SIBLING
;
6260 sd
->cache_nice_tries
= 1;
6265 sd
->private = &tl
->data
;
6271 * Topology list, bottom-up.
6273 static struct sched_domain_topology_level default_topology
[] = {
6274 #ifdef CONFIG_SCHED_SMT
6275 { cpu_smt_mask
, cpu_smt_flags
, SD_INIT_NAME(SMT
) },
6277 #ifdef CONFIG_SCHED_MC
6278 { cpu_coregroup_mask
, cpu_core_flags
, SD_INIT_NAME(MC
) },
6280 { cpu_cpu_mask
, SD_INIT_NAME(DIE
) },
6284 struct sched_domain_topology_level
*sched_domain_topology
= default_topology
;
6286 #define for_each_sd_topology(tl) \
6287 for (tl = sched_domain_topology; tl->mask; tl++)
6289 void set_sched_topology(struct sched_domain_topology_level
*tl
)
6291 sched_domain_topology
= tl
;
6296 static const struct cpumask
*sd_numa_mask(int cpu
)
6298 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6301 static void sched_numa_warn(const char *str
)
6303 static int done
= false;
6311 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6313 for (i
= 0; i
< nr_node_ids
; i
++) {
6314 printk(KERN_WARNING
" ");
6315 for (j
= 0; j
< nr_node_ids
; j
++)
6316 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6317 printk(KERN_CONT
"\n");
6319 printk(KERN_WARNING
"\n");
6322 bool find_numa_distance(int distance
)
6326 if (distance
== node_distance(0, 0))
6329 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6330 if (sched_domains_numa_distance
[i
] == distance
)
6338 * A system can have three types of NUMA topology:
6339 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6340 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6341 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6343 * The difference between a glueless mesh topology and a backplane
6344 * topology lies in whether communication between not directly
6345 * connected nodes goes through intermediary nodes (where programs
6346 * could run), or through backplane controllers. This affects
6347 * placement of programs.
6349 * The type of topology can be discerned with the following tests:
6350 * - If the maximum distance between any nodes is 1 hop, the system
6351 * is directly connected.
6352 * - If for two nodes A and B, located N > 1 hops away from each other,
6353 * there is an intermediary node C, which is < N hops away from both
6354 * nodes A and B, the system is a glueless mesh.
6356 static void init_numa_topology_type(void)
6360 n
= sched_max_numa_distance
;
6363 sched_numa_topology_type
= NUMA_DIRECT
;
6365 for_each_online_node(a
) {
6366 for_each_online_node(b
) {
6367 /* Find two nodes furthest removed from each other. */
6368 if (node_distance(a
, b
) < n
)
6371 /* Is there an intermediary node between a and b? */
6372 for_each_online_node(c
) {
6373 if (node_distance(a
, c
) < n
&&
6374 node_distance(b
, c
) < n
) {
6375 sched_numa_topology_type
=
6381 sched_numa_topology_type
= NUMA_BACKPLANE
;
6387 static void sched_init_numa(void)
6389 int next_distance
, curr_distance
= node_distance(0, 0);
6390 struct sched_domain_topology_level
*tl
;
6394 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6395 if (!sched_domains_numa_distance
)
6399 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6400 * unique distances in the node_distance() table.
6402 * Assumes node_distance(0,j) includes all distances in
6403 * node_distance(i,j) in order to avoid cubic time.
6405 next_distance
= curr_distance
;
6406 for (i
= 0; i
< nr_node_ids
; i
++) {
6407 for (j
= 0; j
< nr_node_ids
; j
++) {
6408 for (k
= 0; k
< nr_node_ids
; k
++) {
6409 int distance
= node_distance(i
, k
);
6411 if (distance
> curr_distance
&&
6412 (distance
< next_distance
||
6413 next_distance
== curr_distance
))
6414 next_distance
= distance
;
6417 * While not a strong assumption it would be nice to know
6418 * about cases where if node A is connected to B, B is not
6419 * equally connected to A.
6421 if (sched_debug() && node_distance(k
, i
) != distance
)
6422 sched_numa_warn("Node-distance not symmetric");
6424 if (sched_debug() && i
&& !find_numa_distance(distance
))
6425 sched_numa_warn("Node-0 not representative");
6427 if (next_distance
!= curr_distance
) {
6428 sched_domains_numa_distance
[level
++] = next_distance
;
6429 sched_domains_numa_levels
= level
;
6430 curr_distance
= next_distance
;
6435 * In case of sched_debug() we verify the above assumption.
6445 * 'level' contains the number of unique distances, excluding the
6446 * identity distance node_distance(i,i).
6448 * The sched_domains_numa_distance[] array includes the actual distance
6453 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6454 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6455 * the array will contain less then 'level' members. This could be
6456 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6457 * in other functions.
6459 * We reset it to 'level' at the end of this function.
6461 sched_domains_numa_levels
= 0;
6463 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6464 if (!sched_domains_numa_masks
)
6468 * Now for each level, construct a mask per node which contains all
6469 * cpus of nodes that are that many hops away from us.
6471 for (i
= 0; i
< level
; i
++) {
6472 sched_domains_numa_masks
[i
] =
6473 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6474 if (!sched_domains_numa_masks
[i
])
6477 for (j
= 0; j
< nr_node_ids
; j
++) {
6478 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6482 sched_domains_numa_masks
[i
][j
] = mask
;
6484 for (k
= 0; k
< nr_node_ids
; k
++) {
6485 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6488 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6493 /* Compute default topology size */
6494 for (i
= 0; sched_domain_topology
[i
].mask
; i
++);
6496 tl
= kzalloc((i
+ level
+ 1) *
6497 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6502 * Copy the default topology bits..
6504 for (i
= 0; sched_domain_topology
[i
].mask
; i
++)
6505 tl
[i
] = sched_domain_topology
[i
];
6508 * .. and append 'j' levels of NUMA goodness.
6510 for (j
= 0; j
< level
; i
++, j
++) {
6511 tl
[i
] = (struct sched_domain_topology_level
){
6512 .mask
= sd_numa_mask
,
6513 .sd_flags
= cpu_numa_flags
,
6514 .flags
= SDTL_OVERLAP
,
6520 sched_domain_topology
= tl
;
6522 sched_domains_numa_levels
= level
;
6523 sched_max_numa_distance
= sched_domains_numa_distance
[level
- 1];
6525 init_numa_topology_type();
6528 static void sched_domains_numa_masks_set(int cpu
)
6531 int node
= cpu_to_node(cpu
);
6533 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6534 for (j
= 0; j
< nr_node_ids
; j
++) {
6535 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6536 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6541 static void sched_domains_numa_masks_clear(int cpu
)
6544 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6545 for (j
= 0; j
< nr_node_ids
; j
++)
6546 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6551 * Update sched_domains_numa_masks[level][node] array when new cpus
6554 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6555 unsigned long action
,
6558 int cpu
= (long)hcpu
;
6560 switch (action
& ~CPU_TASKS_FROZEN
) {
6562 sched_domains_numa_masks_set(cpu
);
6566 sched_domains_numa_masks_clear(cpu
);
6576 static inline void sched_init_numa(void)
6580 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6581 unsigned long action
,
6586 #endif /* CONFIG_NUMA */
6588 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6590 struct sched_domain_topology_level
*tl
;
6593 for_each_sd_topology(tl
) {
6594 struct sd_data
*sdd
= &tl
->data
;
6596 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6600 sdd
->sg
= alloc_percpu(struct sched_group
*);
6604 sdd
->sgc
= alloc_percpu(struct sched_group_capacity
*);
6608 for_each_cpu(j
, cpu_map
) {
6609 struct sched_domain
*sd
;
6610 struct sched_group
*sg
;
6611 struct sched_group_capacity
*sgc
;
6613 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6614 GFP_KERNEL
, cpu_to_node(j
));
6618 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6620 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6621 GFP_KERNEL
, cpu_to_node(j
));
6627 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6629 sgc
= kzalloc_node(sizeof(struct sched_group_capacity
) + cpumask_size(),
6630 GFP_KERNEL
, cpu_to_node(j
));
6634 *per_cpu_ptr(sdd
->sgc
, j
) = sgc
;
6641 static void __sdt_free(const struct cpumask
*cpu_map
)
6643 struct sched_domain_topology_level
*tl
;
6646 for_each_sd_topology(tl
) {
6647 struct sd_data
*sdd
= &tl
->data
;
6649 for_each_cpu(j
, cpu_map
) {
6650 struct sched_domain
*sd
;
6653 sd
= *per_cpu_ptr(sdd
->sd
, j
);
6654 if (sd
&& (sd
->flags
& SD_OVERLAP
))
6655 free_sched_groups(sd
->groups
, 0);
6656 kfree(*per_cpu_ptr(sdd
->sd
, j
));
6660 kfree(*per_cpu_ptr(sdd
->sg
, j
));
6662 kfree(*per_cpu_ptr(sdd
->sgc
, j
));
6664 free_percpu(sdd
->sd
);
6666 free_percpu(sdd
->sg
);
6668 free_percpu(sdd
->sgc
);
6673 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
6674 const struct cpumask
*cpu_map
, struct sched_domain_attr
*attr
,
6675 struct sched_domain
*child
, int cpu
)
6677 struct sched_domain
*sd
= sd_init(tl
, cpu
);
6681 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
6683 sd
->level
= child
->level
+ 1;
6684 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
6688 if (!cpumask_subset(sched_domain_span(child
),
6689 sched_domain_span(sd
))) {
6690 pr_err("BUG: arch topology borken\n");
6691 #ifdef CONFIG_SCHED_DEBUG
6692 pr_err(" the %s domain not a subset of the %s domain\n",
6693 child
->name
, sd
->name
);
6695 /* Fixup, ensure @sd has at least @child cpus. */
6696 cpumask_or(sched_domain_span(sd
),
6697 sched_domain_span(sd
),
6698 sched_domain_span(child
));
6702 set_domain_attribute(sd
, attr
);
6708 * Build sched domains for a given set of cpus and attach the sched domains
6709 * to the individual cpus
6711 static int build_sched_domains(const struct cpumask
*cpu_map
,
6712 struct sched_domain_attr
*attr
)
6714 enum s_alloc alloc_state
;
6715 struct sched_domain
*sd
;
6717 int i
, ret
= -ENOMEM
;
6719 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
6720 if (alloc_state
!= sa_rootdomain
)
6723 /* Set up domains for cpus specified by the cpu_map. */
6724 for_each_cpu(i
, cpu_map
) {
6725 struct sched_domain_topology_level
*tl
;
6728 for_each_sd_topology(tl
) {
6729 sd
= build_sched_domain(tl
, cpu_map
, attr
, sd
, i
);
6730 if (tl
== sched_domain_topology
)
6731 *per_cpu_ptr(d
.sd
, i
) = sd
;
6732 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
6733 sd
->flags
|= SD_OVERLAP
;
6734 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
6739 /* Build the groups for the domains */
6740 for_each_cpu(i
, cpu_map
) {
6741 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6742 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
6743 if (sd
->flags
& SD_OVERLAP
) {
6744 if (build_overlap_sched_groups(sd
, i
))
6747 if (build_sched_groups(sd
, i
))
6753 /* Calculate CPU capacity for physical packages and nodes */
6754 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
6755 if (!cpumask_test_cpu(i
, cpu_map
))
6758 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
6759 claim_allocations(i
, sd
);
6760 init_sched_groups_capacity(i
, sd
);
6764 /* Attach the domains */
6766 for_each_cpu(i
, cpu_map
) {
6767 sd
= *per_cpu_ptr(d
.sd
, i
);
6768 cpu_attach_domain(sd
, d
.rd
, i
);
6774 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
6778 static cpumask_var_t
*doms_cur
; /* current sched domains */
6779 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6780 static struct sched_domain_attr
*dattr_cur
;
6781 /* attribues of custom domains in 'doms_cur' */
6784 * Special case: If a kmalloc of a doms_cur partition (array of
6785 * cpumask) fails, then fallback to a single sched domain,
6786 * as determined by the single cpumask fallback_doms.
6788 static cpumask_var_t fallback_doms
;
6791 * arch_update_cpu_topology lets virtualized architectures update the
6792 * cpu core maps. It is supposed to return 1 if the topology changed
6793 * or 0 if it stayed the same.
6795 int __weak
arch_update_cpu_topology(void)
6800 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
6803 cpumask_var_t
*doms
;
6805 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
6808 for (i
= 0; i
< ndoms
; i
++) {
6809 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
6810 free_sched_domains(doms
, i
);
6817 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
6820 for (i
= 0; i
< ndoms
; i
++)
6821 free_cpumask_var(doms
[i
]);
6826 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6827 * For now this just excludes isolated cpus, but could be used to
6828 * exclude other special cases in the future.
6830 static int init_sched_domains(const struct cpumask
*cpu_map
)
6834 arch_update_cpu_topology();
6836 doms_cur
= alloc_sched_domains(ndoms_cur
);
6838 doms_cur
= &fallback_doms
;
6839 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
6840 err
= build_sched_domains(doms_cur
[0], NULL
);
6841 register_sched_domain_sysctl();
6847 * Detach sched domains from a group of cpus specified in cpu_map
6848 * These cpus will now be attached to the NULL domain
6850 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
6855 for_each_cpu(i
, cpu_map
)
6856 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6860 /* handle null as "default" */
6861 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
6862 struct sched_domain_attr
*new, int idx_new
)
6864 struct sched_domain_attr tmp
;
6871 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
6872 new ? (new + idx_new
) : &tmp
,
6873 sizeof(struct sched_domain_attr
));
6877 * Partition sched domains as specified by the 'ndoms_new'
6878 * cpumasks in the array doms_new[] of cpumasks. This compares
6879 * doms_new[] to the current sched domain partitioning, doms_cur[].
6880 * It destroys each deleted domain and builds each new domain.
6882 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
6883 * The masks don't intersect (don't overlap.) We should setup one
6884 * sched domain for each mask. CPUs not in any of the cpumasks will
6885 * not be load balanced. If the same cpumask appears both in the
6886 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6889 * The passed in 'doms_new' should be allocated using
6890 * alloc_sched_domains. This routine takes ownership of it and will
6891 * free_sched_domains it when done with it. If the caller failed the
6892 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
6893 * and partition_sched_domains() will fallback to the single partition
6894 * 'fallback_doms', it also forces the domains to be rebuilt.
6896 * If doms_new == NULL it will be replaced with cpu_online_mask.
6897 * ndoms_new == 0 is a special case for destroying existing domains,
6898 * and it will not create the default domain.
6900 * Call with hotplug lock held
6902 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
6903 struct sched_domain_attr
*dattr_new
)
6908 mutex_lock(&sched_domains_mutex
);
6910 /* always unregister in case we don't destroy any domains */
6911 unregister_sched_domain_sysctl();
6913 /* Let architecture update cpu core mappings. */
6914 new_topology
= arch_update_cpu_topology();
6916 n
= doms_new
? ndoms_new
: 0;
6918 /* Destroy deleted domains */
6919 for (i
= 0; i
< ndoms_cur
; i
++) {
6920 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6921 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
6922 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
6925 /* no match - a current sched domain not in new doms_new[] */
6926 detach_destroy_domains(doms_cur
[i
]);
6932 if (doms_new
== NULL
) {
6934 doms_new
= &fallback_doms
;
6935 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
6936 WARN_ON_ONCE(dattr_new
);
6939 /* Build new domains */
6940 for (i
= 0; i
< ndoms_new
; i
++) {
6941 for (j
= 0; j
< n
&& !new_topology
; j
++) {
6942 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
6943 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
6946 /* no match - add a new doms_new */
6947 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
6952 /* Remember the new sched domains */
6953 if (doms_cur
!= &fallback_doms
)
6954 free_sched_domains(doms_cur
, ndoms_cur
);
6955 kfree(dattr_cur
); /* kfree(NULL) is safe */
6956 doms_cur
= doms_new
;
6957 dattr_cur
= dattr_new
;
6958 ndoms_cur
= ndoms_new
;
6960 register_sched_domain_sysctl();
6962 mutex_unlock(&sched_domains_mutex
);
6965 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
6968 * Update cpusets according to cpu_active mask. If cpusets are
6969 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
6970 * around partition_sched_domains().
6972 * If we come here as part of a suspend/resume, don't touch cpusets because we
6973 * want to restore it back to its original state upon resume anyway.
6975 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
6979 case CPU_ONLINE_FROZEN
:
6980 case CPU_DOWN_FAILED_FROZEN
:
6983 * num_cpus_frozen tracks how many CPUs are involved in suspend
6984 * resume sequence. As long as this is not the last online
6985 * operation in the resume sequence, just build a single sched
6986 * domain, ignoring cpusets.
6989 if (likely(num_cpus_frozen
)) {
6990 partition_sched_domains(1, NULL
, NULL
);
6995 * This is the last CPU online operation. So fall through and
6996 * restore the original sched domains by considering the
6997 * cpuset configurations.
7001 case CPU_DOWN_FAILED
:
7002 cpuset_update_active_cpus(true);
7010 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
7014 case CPU_DOWN_PREPARE
:
7015 cpuset_update_active_cpus(false);
7017 case CPU_DOWN_PREPARE_FROZEN
:
7019 partition_sched_domains(1, NULL
, NULL
);
7027 void __init
sched_init_smp(void)
7029 cpumask_var_t non_isolated_cpus
;
7031 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
7032 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
7037 * There's no userspace yet to cause hotplug operations; hence all the
7038 * cpu masks are stable and all blatant races in the below code cannot
7041 mutex_lock(&sched_domains_mutex
);
7042 init_sched_domains(cpu_active_mask
);
7043 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
7044 if (cpumask_empty(non_isolated_cpus
))
7045 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
7046 mutex_unlock(&sched_domains_mutex
);
7048 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
7049 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
7050 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
7054 /* Move init over to a non-isolated CPU */
7055 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
7057 sched_init_granularity();
7058 free_cpumask_var(non_isolated_cpus
);
7060 init_sched_rt_class();
7061 init_sched_dl_class();
7064 void __init
sched_init_smp(void)
7066 sched_init_granularity();
7068 #endif /* CONFIG_SMP */
7070 const_debug
unsigned int sysctl_timer_migration
= 1;
7072 int in_sched_functions(unsigned long addr
)
7074 return in_lock_functions(addr
) ||
7075 (addr
>= (unsigned long)__sched_text_start
7076 && addr
< (unsigned long)__sched_text_end
);
7079 #ifdef CONFIG_CGROUP_SCHED
7081 * Default task group.
7082 * Every task in system belongs to this group at bootup.
7084 struct task_group root_task_group
;
7085 LIST_HEAD(task_groups
);
7088 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
7090 void __init
sched_init(void)
7093 unsigned long alloc_size
= 0, ptr
;
7095 #ifdef CONFIG_FAIR_GROUP_SCHED
7096 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7098 #ifdef CONFIG_RT_GROUP_SCHED
7099 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7102 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
7104 #ifdef CONFIG_FAIR_GROUP_SCHED
7105 root_task_group
.se
= (struct sched_entity
**)ptr
;
7106 ptr
+= nr_cpu_ids
* sizeof(void **);
7108 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
7109 ptr
+= nr_cpu_ids
* sizeof(void **);
7111 #endif /* CONFIG_FAIR_GROUP_SCHED */
7112 #ifdef CONFIG_RT_GROUP_SCHED
7113 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
7114 ptr
+= nr_cpu_ids
* sizeof(void **);
7116 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
7117 ptr
+= nr_cpu_ids
* sizeof(void **);
7119 #endif /* CONFIG_RT_GROUP_SCHED */
7121 #ifdef CONFIG_CPUMASK_OFFSTACK
7122 for_each_possible_cpu(i
) {
7123 per_cpu(load_balance_mask
, i
) = (cpumask_var_t
)kzalloc_node(
7124 cpumask_size(), GFP_KERNEL
, cpu_to_node(i
));
7126 #endif /* CONFIG_CPUMASK_OFFSTACK */
7128 init_rt_bandwidth(&def_rt_bandwidth
,
7129 global_rt_period(), global_rt_runtime());
7130 init_dl_bandwidth(&def_dl_bandwidth
,
7131 global_rt_period(), global_rt_runtime());
7134 init_defrootdomain();
7137 #ifdef CONFIG_RT_GROUP_SCHED
7138 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
7139 global_rt_period(), global_rt_runtime());
7140 #endif /* CONFIG_RT_GROUP_SCHED */
7142 #ifdef CONFIG_CGROUP_SCHED
7143 list_add(&root_task_group
.list
, &task_groups
);
7144 INIT_LIST_HEAD(&root_task_group
.children
);
7145 INIT_LIST_HEAD(&root_task_group
.siblings
);
7146 autogroup_init(&init_task
);
7148 #endif /* CONFIG_CGROUP_SCHED */
7150 for_each_possible_cpu(i
) {
7154 raw_spin_lock_init(&rq
->lock
);
7156 rq
->calc_load_active
= 0;
7157 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
7158 init_cfs_rq(&rq
->cfs
);
7159 init_rt_rq(&rq
->rt
, rq
);
7160 init_dl_rq(&rq
->dl
, rq
);
7161 #ifdef CONFIG_FAIR_GROUP_SCHED
7162 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
7163 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
7165 * How much cpu bandwidth does root_task_group get?
7167 * In case of task-groups formed thr' the cgroup filesystem, it
7168 * gets 100% of the cpu resources in the system. This overall
7169 * system cpu resource is divided among the tasks of
7170 * root_task_group and its child task-groups in a fair manner,
7171 * based on each entity's (task or task-group's) weight
7172 * (se->load.weight).
7174 * In other words, if root_task_group has 10 tasks of weight
7175 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7176 * then A0's share of the cpu resource is:
7178 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7180 * We achieve this by letting root_task_group's tasks sit
7181 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7183 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
7184 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
7185 #endif /* CONFIG_FAIR_GROUP_SCHED */
7187 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
7188 #ifdef CONFIG_RT_GROUP_SCHED
7189 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
7192 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7193 rq
->cpu_load
[j
] = 0;
7195 rq
->last_load_update_tick
= jiffies
;
7200 rq
->cpu_capacity
= SCHED_CAPACITY_SCALE
;
7201 rq
->post_schedule
= 0;
7202 rq
->active_balance
= 0;
7203 rq
->next_balance
= jiffies
;
7208 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
7209 rq
->max_idle_balance_cost
= sysctl_sched_migration_cost
;
7211 INIT_LIST_HEAD(&rq
->cfs_tasks
);
7213 rq_attach_root(rq
, &def_root_domain
);
7214 #ifdef CONFIG_NO_HZ_COMMON
7217 #ifdef CONFIG_NO_HZ_FULL
7218 rq
->last_sched_tick
= 0;
7222 atomic_set(&rq
->nr_iowait
, 0);
7225 set_load_weight(&init_task
);
7227 #ifdef CONFIG_PREEMPT_NOTIFIERS
7228 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7232 * The boot idle thread does lazy MMU switching as well:
7234 atomic_inc(&init_mm
.mm_count
);
7235 enter_lazy_tlb(&init_mm
, current
);
7238 * During early bootup we pretend to be a normal task:
7240 current
->sched_class
= &fair_sched_class
;
7243 * Make us the idle thread. Technically, schedule() should not be
7244 * called from this thread, however somewhere below it might be,
7245 * but because we are the idle thread, we just pick up running again
7246 * when this runqueue becomes "idle".
7248 init_idle(current
, smp_processor_id());
7250 calc_load_update
= jiffies
+ LOAD_FREQ
;
7253 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
7254 /* May be allocated at isolcpus cmdline parse time */
7255 if (cpu_isolated_map
== NULL
)
7256 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
7257 idle_thread_set_boot_cpu();
7258 set_cpu_rq_start_time();
7260 init_sched_fair_class();
7262 scheduler_running
= 1;
7265 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7266 static inline int preempt_count_equals(int preempt_offset
)
7268 int nested
= (preempt_count() & ~PREEMPT_ACTIVE
) + rcu_preempt_depth();
7270 return (nested
== preempt_offset
);
7273 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7276 * Blocking primitives will set (and therefore destroy) current->state,
7277 * since we will exit with TASK_RUNNING make sure we enter with it,
7278 * otherwise we will destroy state.
7280 WARN_ONCE(current
->state
!= TASK_RUNNING
&& current
->task_state_change
,
7281 "do not call blocking ops when !TASK_RUNNING; "
7282 "state=%lx set at [<%p>] %pS\n",
7284 (void *)current
->task_state_change
,
7285 (void *)current
->task_state_change
);
7287 ___might_sleep(file
, line
, preempt_offset
);
7289 EXPORT_SYMBOL(__might_sleep
);
7291 void ___might_sleep(const char *file
, int line
, int preempt_offset
)
7293 static unsigned long prev_jiffy
; /* ratelimiting */
7295 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7296 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled() &&
7297 !is_idle_task(current
)) ||
7298 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7300 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7302 prev_jiffy
= jiffies
;
7305 "BUG: sleeping function called from invalid context at %s:%d\n",
7308 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7309 in_atomic(), irqs_disabled(),
7310 current
->pid
, current
->comm
);
7312 if (task_stack_end_corrupted(current
))
7313 printk(KERN_EMERG
"Thread overran stack, or stack corrupted\n");
7315 debug_show_held_locks(current
);
7316 if (irqs_disabled())
7317 print_irqtrace_events(current
);
7318 #ifdef CONFIG_DEBUG_PREEMPT
7319 if (!preempt_count_equals(preempt_offset
)) {
7320 pr_err("Preemption disabled at:");
7321 print_ip_sym(current
->preempt_disable_ip
);
7327 EXPORT_SYMBOL(___might_sleep
);
7330 #ifdef CONFIG_MAGIC_SYSRQ
7331 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7333 const struct sched_class
*prev_class
= p
->sched_class
;
7334 struct sched_attr attr
= {
7335 .sched_policy
= SCHED_NORMAL
,
7337 int old_prio
= p
->prio
;
7340 queued
= task_on_rq_queued(p
);
7342 dequeue_task(rq
, p
, 0);
7343 __setscheduler(rq
, p
, &attr
);
7345 enqueue_task(rq
, p
, 0);
7349 check_class_changed(rq
, p
, prev_class
, old_prio
);
7352 void normalize_rt_tasks(void)
7354 struct task_struct
*g
, *p
;
7355 unsigned long flags
;
7358 read_lock(&tasklist_lock
);
7359 for_each_process_thread(g
, p
) {
7361 * Only normalize user tasks:
7363 if (p
->flags
& PF_KTHREAD
)
7366 p
->se
.exec_start
= 0;
7367 #ifdef CONFIG_SCHEDSTATS
7368 p
->se
.statistics
.wait_start
= 0;
7369 p
->se
.statistics
.sleep_start
= 0;
7370 p
->se
.statistics
.block_start
= 0;
7373 if (!dl_task(p
) && !rt_task(p
)) {
7375 * Renice negative nice level userspace
7378 if (task_nice(p
) < 0)
7379 set_user_nice(p
, 0);
7383 rq
= task_rq_lock(p
, &flags
);
7384 normalize_task(rq
, p
);
7385 task_rq_unlock(rq
, p
, &flags
);
7387 read_unlock(&tasklist_lock
);
7390 #endif /* CONFIG_MAGIC_SYSRQ */
7392 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7394 * These functions are only useful for the IA64 MCA handling, or kdb.
7396 * They can only be called when the whole system has been
7397 * stopped - every CPU needs to be quiescent, and no scheduling
7398 * activity can take place. Using them for anything else would
7399 * be a serious bug, and as a result, they aren't even visible
7400 * under any other configuration.
7404 * curr_task - return the current task for a given cpu.
7405 * @cpu: the processor in question.
7407 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7409 * Return: The current task for @cpu.
7411 struct task_struct
*curr_task(int cpu
)
7413 return cpu_curr(cpu
);
7416 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7420 * set_curr_task - set the current task for a given cpu.
7421 * @cpu: the processor in question.
7422 * @p: the task pointer to set.
7424 * Description: This function must only be used when non-maskable interrupts
7425 * are serviced on a separate stack. It allows the architecture to switch the
7426 * notion of the current task on a cpu in a non-blocking manner. This function
7427 * must be called with all CPU's synchronized, and interrupts disabled, the
7428 * and caller must save the original value of the current task (see
7429 * curr_task() above) and restore that value before reenabling interrupts and
7430 * re-starting the system.
7432 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7434 void set_curr_task(int cpu
, struct task_struct
*p
)
7441 #ifdef CONFIG_CGROUP_SCHED
7442 /* task_group_lock serializes the addition/removal of task groups */
7443 static DEFINE_SPINLOCK(task_group_lock
);
7445 static void free_sched_group(struct task_group
*tg
)
7447 free_fair_sched_group(tg
);
7448 free_rt_sched_group(tg
);
7453 /* allocate runqueue etc for a new task group */
7454 struct task_group
*sched_create_group(struct task_group
*parent
)
7456 struct task_group
*tg
;
7458 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7460 return ERR_PTR(-ENOMEM
);
7462 if (!alloc_fair_sched_group(tg
, parent
))
7465 if (!alloc_rt_sched_group(tg
, parent
))
7471 free_sched_group(tg
);
7472 return ERR_PTR(-ENOMEM
);
7475 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7477 unsigned long flags
;
7479 spin_lock_irqsave(&task_group_lock
, flags
);
7480 list_add_rcu(&tg
->list
, &task_groups
);
7482 WARN_ON(!parent
); /* root should already exist */
7484 tg
->parent
= parent
;
7485 INIT_LIST_HEAD(&tg
->children
);
7486 list_add_rcu(&tg
->siblings
, &parent
->children
);
7487 spin_unlock_irqrestore(&task_group_lock
, flags
);
7490 /* rcu callback to free various structures associated with a task group */
7491 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7493 /* now it should be safe to free those cfs_rqs */
7494 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7497 /* Destroy runqueue etc associated with a task group */
7498 void sched_destroy_group(struct task_group
*tg
)
7500 /* wait for possible concurrent references to cfs_rqs complete */
7501 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7504 void sched_offline_group(struct task_group
*tg
)
7506 unsigned long flags
;
7509 /* end participation in shares distribution */
7510 for_each_possible_cpu(i
)
7511 unregister_fair_sched_group(tg
, i
);
7513 spin_lock_irqsave(&task_group_lock
, flags
);
7514 list_del_rcu(&tg
->list
);
7515 list_del_rcu(&tg
->siblings
);
7516 spin_unlock_irqrestore(&task_group_lock
, flags
);
7519 /* change task's runqueue when it moves between groups.
7520 * The caller of this function should have put the task in its new group
7521 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7522 * reflect its new group.
7524 void sched_move_task(struct task_struct
*tsk
)
7526 struct task_group
*tg
;
7527 int queued
, running
;
7528 unsigned long flags
;
7531 rq
= task_rq_lock(tsk
, &flags
);
7533 running
= task_current(rq
, tsk
);
7534 queued
= task_on_rq_queued(tsk
);
7537 dequeue_task(rq
, tsk
, 0);
7538 if (unlikely(running
))
7539 put_prev_task(rq
, tsk
);
7542 * All callers are synchronized by task_rq_lock(); we do not use RCU
7543 * which is pointless here. Thus, we pass "true" to task_css_check()
7544 * to prevent lockdep warnings.
7546 tg
= container_of(task_css_check(tsk
, cpu_cgrp_id
, true),
7547 struct task_group
, css
);
7548 tg
= autogroup_task_group(tsk
, tg
);
7549 tsk
->sched_task_group
= tg
;
7551 #ifdef CONFIG_FAIR_GROUP_SCHED
7552 if (tsk
->sched_class
->task_move_group
)
7553 tsk
->sched_class
->task_move_group(tsk
, queued
);
7556 set_task_rq(tsk
, task_cpu(tsk
));
7558 if (unlikely(running
))
7559 tsk
->sched_class
->set_curr_task(rq
);
7561 enqueue_task(rq
, tsk
, 0);
7563 task_rq_unlock(rq
, tsk
, &flags
);
7565 #endif /* CONFIG_CGROUP_SCHED */
7567 #ifdef CONFIG_RT_GROUP_SCHED
7569 * Ensure that the real time constraints are schedulable.
7571 static DEFINE_MUTEX(rt_constraints_mutex
);
7573 /* Must be called with tasklist_lock held */
7574 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7576 struct task_struct
*g
, *p
;
7579 * Autogroups do not have RT tasks; see autogroup_create().
7581 if (task_group_is_autogroup(tg
))
7584 for_each_process_thread(g
, p
) {
7585 if (rt_task(p
) && task_group(p
) == tg
)
7592 struct rt_schedulable_data
{
7593 struct task_group
*tg
;
7598 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7600 struct rt_schedulable_data
*d
= data
;
7601 struct task_group
*child
;
7602 unsigned long total
, sum
= 0;
7603 u64 period
, runtime
;
7605 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7606 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7609 period
= d
->rt_period
;
7610 runtime
= d
->rt_runtime
;
7614 * Cannot have more runtime than the period.
7616 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7620 * Ensure we don't starve existing RT tasks.
7622 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7625 total
= to_ratio(period
, runtime
);
7628 * Nobody can have more than the global setting allows.
7630 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7634 * The sum of our children's runtime should not exceed our own.
7636 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7637 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7638 runtime
= child
->rt_bandwidth
.rt_runtime
;
7640 if (child
== d
->tg
) {
7641 period
= d
->rt_period
;
7642 runtime
= d
->rt_runtime
;
7645 sum
+= to_ratio(period
, runtime
);
7654 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7658 struct rt_schedulable_data data
= {
7660 .rt_period
= period
,
7661 .rt_runtime
= runtime
,
7665 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
7671 static int tg_set_rt_bandwidth(struct task_group
*tg
,
7672 u64 rt_period
, u64 rt_runtime
)
7677 * Disallowing the root group RT runtime is BAD, it would disallow the
7678 * kernel creating (and or operating) RT threads.
7680 if (tg
== &root_task_group
&& rt_runtime
== 0)
7683 /* No period doesn't make any sense. */
7687 mutex_lock(&rt_constraints_mutex
);
7688 read_lock(&tasklist_lock
);
7689 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
7693 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7694 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
7695 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
7697 for_each_possible_cpu(i
) {
7698 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
7700 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7701 rt_rq
->rt_runtime
= rt_runtime
;
7702 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7704 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
7706 read_unlock(&tasklist_lock
);
7707 mutex_unlock(&rt_constraints_mutex
);
7712 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7714 u64 rt_runtime
, rt_period
;
7716 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7717 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7718 if (rt_runtime_us
< 0)
7719 rt_runtime
= RUNTIME_INF
;
7721 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7724 static long sched_group_rt_runtime(struct task_group
*tg
)
7728 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
7731 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
7732 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7733 return rt_runtime_us
;
7736 static int sched_group_set_rt_period(struct task_group
*tg
, long rt_period_us
)
7738 u64 rt_runtime
, rt_period
;
7740 rt_period
= (u64
)rt_period_us
* NSEC_PER_USEC
;
7741 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
7743 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
7746 static long sched_group_rt_period(struct task_group
*tg
)
7750 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7751 do_div(rt_period_us
, NSEC_PER_USEC
);
7752 return rt_period_us
;
7754 #endif /* CONFIG_RT_GROUP_SCHED */
7756 #ifdef CONFIG_RT_GROUP_SCHED
7757 static int sched_rt_global_constraints(void)
7761 mutex_lock(&rt_constraints_mutex
);
7762 read_lock(&tasklist_lock
);
7763 ret
= __rt_schedulable(NULL
, 0, 0);
7764 read_unlock(&tasklist_lock
);
7765 mutex_unlock(&rt_constraints_mutex
);
7770 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
7772 /* Don't accept realtime tasks when there is no way for them to run */
7773 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
7779 #else /* !CONFIG_RT_GROUP_SCHED */
7780 static int sched_rt_global_constraints(void)
7782 unsigned long flags
;
7785 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7786 for_each_possible_cpu(i
) {
7787 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
7789 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
7790 rt_rq
->rt_runtime
= global_rt_runtime();
7791 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
7793 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
7797 #endif /* CONFIG_RT_GROUP_SCHED */
7799 static int sched_dl_global_constraints(void)
7801 u64 runtime
= global_rt_runtime();
7802 u64 period
= global_rt_period();
7803 u64 new_bw
= to_ratio(period
, runtime
);
7806 unsigned long flags
;
7809 * Here we want to check the bandwidth not being set to some
7810 * value smaller than the currently allocated bandwidth in
7811 * any of the root_domains.
7813 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
7814 * cycling on root_domains... Discussion on different/better
7815 * solutions is welcome!
7817 for_each_possible_cpu(cpu
) {
7818 rcu_read_lock_sched();
7819 dl_b
= dl_bw_of(cpu
);
7821 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
7822 if (new_bw
< dl_b
->total_bw
)
7824 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
7826 rcu_read_unlock_sched();
7835 static void sched_dl_do_global(void)
7840 unsigned long flags
;
7842 def_dl_bandwidth
.dl_period
= global_rt_period();
7843 def_dl_bandwidth
.dl_runtime
= global_rt_runtime();
7845 if (global_rt_runtime() != RUNTIME_INF
)
7846 new_bw
= to_ratio(global_rt_period(), global_rt_runtime());
7849 * FIXME: As above...
7851 for_each_possible_cpu(cpu
) {
7852 rcu_read_lock_sched();
7853 dl_b
= dl_bw_of(cpu
);
7855 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
7857 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
7859 rcu_read_unlock_sched();
7863 static int sched_rt_global_validate(void)
7865 if (sysctl_sched_rt_period
<= 0)
7868 if ((sysctl_sched_rt_runtime
!= RUNTIME_INF
) &&
7869 (sysctl_sched_rt_runtime
> sysctl_sched_rt_period
))
7875 static void sched_rt_do_global(void)
7877 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
7878 def_rt_bandwidth
.rt_period
= ns_to_ktime(global_rt_period());
7881 int sched_rt_handler(struct ctl_table
*table
, int write
,
7882 void __user
*buffer
, size_t *lenp
,
7885 int old_period
, old_runtime
;
7886 static DEFINE_MUTEX(mutex
);
7890 old_period
= sysctl_sched_rt_period
;
7891 old_runtime
= sysctl_sched_rt_runtime
;
7893 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7895 if (!ret
&& write
) {
7896 ret
= sched_rt_global_validate();
7900 ret
= sched_rt_global_constraints();
7904 ret
= sched_dl_global_constraints();
7908 sched_rt_do_global();
7909 sched_dl_do_global();
7913 sysctl_sched_rt_period
= old_period
;
7914 sysctl_sched_rt_runtime
= old_runtime
;
7916 mutex_unlock(&mutex
);
7921 int sched_rr_handler(struct ctl_table
*table
, int write
,
7922 void __user
*buffer
, size_t *lenp
,
7926 static DEFINE_MUTEX(mutex
);
7929 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
7930 /* make sure that internally we keep jiffies */
7931 /* also, writing zero resets timeslice to default */
7932 if (!ret
&& write
) {
7933 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
7934 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
7936 mutex_unlock(&mutex
);
7940 #ifdef CONFIG_CGROUP_SCHED
7942 static inline struct task_group
*css_tg(struct cgroup_subsys_state
*css
)
7944 return css
? container_of(css
, struct task_group
, css
) : NULL
;
7947 static struct cgroup_subsys_state
*
7948 cpu_cgroup_css_alloc(struct cgroup_subsys_state
*parent_css
)
7950 struct task_group
*parent
= css_tg(parent_css
);
7951 struct task_group
*tg
;
7954 /* This is early initialization for the top cgroup */
7955 return &root_task_group
.css
;
7958 tg
= sched_create_group(parent
);
7960 return ERR_PTR(-ENOMEM
);
7965 static int cpu_cgroup_css_online(struct cgroup_subsys_state
*css
)
7967 struct task_group
*tg
= css_tg(css
);
7968 struct task_group
*parent
= css_tg(css
->parent
);
7971 sched_online_group(tg
, parent
);
7975 static void cpu_cgroup_css_free(struct cgroup_subsys_state
*css
)
7977 struct task_group
*tg
= css_tg(css
);
7979 sched_destroy_group(tg
);
7982 static void cpu_cgroup_css_offline(struct cgroup_subsys_state
*css
)
7984 struct task_group
*tg
= css_tg(css
);
7986 sched_offline_group(tg
);
7989 static void cpu_cgroup_fork(struct task_struct
*task
)
7991 sched_move_task(task
);
7994 static int cpu_cgroup_can_attach(struct cgroup_subsys_state
*css
,
7995 struct cgroup_taskset
*tset
)
7997 struct task_struct
*task
;
7999 cgroup_taskset_for_each(task
, tset
) {
8000 #ifdef CONFIG_RT_GROUP_SCHED
8001 if (!sched_rt_can_attach(css_tg(css
), task
))
8004 /* We don't support RT-tasks being in separate groups */
8005 if (task
->sched_class
!= &fair_sched_class
)
8012 static void cpu_cgroup_attach(struct cgroup_subsys_state
*css
,
8013 struct cgroup_taskset
*tset
)
8015 struct task_struct
*task
;
8017 cgroup_taskset_for_each(task
, tset
)
8018 sched_move_task(task
);
8021 static void cpu_cgroup_exit(struct cgroup_subsys_state
*css
,
8022 struct cgroup_subsys_state
*old_css
,
8023 struct task_struct
*task
)
8026 * cgroup_exit() is called in the copy_process() failure path.
8027 * Ignore this case since the task hasn't ran yet, this avoids
8028 * trying to poke a half freed task state from generic code.
8030 if (!(task
->flags
& PF_EXITING
))
8033 sched_move_task(task
);
8036 #ifdef CONFIG_FAIR_GROUP_SCHED
8037 static int cpu_shares_write_u64(struct cgroup_subsys_state
*css
,
8038 struct cftype
*cftype
, u64 shareval
)
8040 return sched_group_set_shares(css_tg(css
), scale_load(shareval
));
8043 static u64
cpu_shares_read_u64(struct cgroup_subsys_state
*css
,
8046 struct task_group
*tg
= css_tg(css
);
8048 return (u64
) scale_load_down(tg
->shares
);
8051 #ifdef CONFIG_CFS_BANDWIDTH
8052 static DEFINE_MUTEX(cfs_constraints_mutex
);
8054 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
8055 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
8057 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
8059 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
8061 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
8062 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8064 if (tg
== &root_task_group
)
8068 * Ensure we have at some amount of bandwidth every period. This is
8069 * to prevent reaching a state of large arrears when throttled via
8070 * entity_tick() resulting in prolonged exit starvation.
8072 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
8076 * Likewise, bound things on the otherside by preventing insane quota
8077 * periods. This also allows us to normalize in computing quota
8080 if (period
> max_cfs_quota_period
)
8084 * Prevent race between setting of cfs_rq->runtime_enabled and
8085 * unthrottle_offline_cfs_rqs().
8088 mutex_lock(&cfs_constraints_mutex
);
8089 ret
= __cfs_schedulable(tg
, period
, quota
);
8093 runtime_enabled
= quota
!= RUNTIME_INF
;
8094 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
8096 * If we need to toggle cfs_bandwidth_used, off->on must occur
8097 * before making related changes, and on->off must occur afterwards
8099 if (runtime_enabled
&& !runtime_was_enabled
)
8100 cfs_bandwidth_usage_inc();
8101 raw_spin_lock_irq(&cfs_b
->lock
);
8102 cfs_b
->period
= ns_to_ktime(period
);
8103 cfs_b
->quota
= quota
;
8105 __refill_cfs_bandwidth_runtime(cfs_b
);
8106 /* restart the period timer (if active) to handle new period expiry */
8107 if (runtime_enabled
&& cfs_b
->timer_active
) {
8108 /* force a reprogram */
8109 __start_cfs_bandwidth(cfs_b
, true);
8111 raw_spin_unlock_irq(&cfs_b
->lock
);
8113 for_each_online_cpu(i
) {
8114 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
8115 struct rq
*rq
= cfs_rq
->rq
;
8117 raw_spin_lock_irq(&rq
->lock
);
8118 cfs_rq
->runtime_enabled
= runtime_enabled
;
8119 cfs_rq
->runtime_remaining
= 0;
8121 if (cfs_rq
->throttled
)
8122 unthrottle_cfs_rq(cfs_rq
);
8123 raw_spin_unlock_irq(&rq
->lock
);
8125 if (runtime_was_enabled
&& !runtime_enabled
)
8126 cfs_bandwidth_usage_dec();
8128 mutex_unlock(&cfs_constraints_mutex
);
8134 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
8138 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8139 if (cfs_quota_us
< 0)
8140 quota
= RUNTIME_INF
;
8142 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
8144 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8147 long tg_get_cfs_quota(struct task_group
*tg
)
8151 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
8154 quota_us
= tg
->cfs_bandwidth
.quota
;
8155 do_div(quota_us
, NSEC_PER_USEC
);
8160 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
8164 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
8165 quota
= tg
->cfs_bandwidth
.quota
;
8167 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8170 long tg_get_cfs_period(struct task_group
*tg
)
8174 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8175 do_div(cfs_period_us
, NSEC_PER_USEC
);
8177 return cfs_period_us
;
8180 static s64
cpu_cfs_quota_read_s64(struct cgroup_subsys_state
*css
,
8183 return tg_get_cfs_quota(css_tg(css
));
8186 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state
*css
,
8187 struct cftype
*cftype
, s64 cfs_quota_us
)
8189 return tg_set_cfs_quota(css_tg(css
), cfs_quota_us
);
8192 static u64
cpu_cfs_period_read_u64(struct cgroup_subsys_state
*css
,
8195 return tg_get_cfs_period(css_tg(css
));
8198 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state
*css
,
8199 struct cftype
*cftype
, u64 cfs_period_us
)
8201 return tg_set_cfs_period(css_tg(css
), cfs_period_us
);
8204 struct cfs_schedulable_data
{
8205 struct task_group
*tg
;
8210 * normalize group quota/period to be quota/max_period
8211 * note: units are usecs
8213 static u64
normalize_cfs_quota(struct task_group
*tg
,
8214 struct cfs_schedulable_data
*d
)
8222 period
= tg_get_cfs_period(tg
);
8223 quota
= tg_get_cfs_quota(tg
);
8226 /* note: these should typically be equivalent */
8227 if (quota
== RUNTIME_INF
|| quota
== -1)
8230 return to_ratio(period
, quota
);
8233 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
8235 struct cfs_schedulable_data
*d
= data
;
8236 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8237 s64 quota
= 0, parent_quota
= -1;
8240 quota
= RUNTIME_INF
;
8242 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
8244 quota
= normalize_cfs_quota(tg
, d
);
8245 parent_quota
= parent_b
->hierarchical_quota
;
8248 * ensure max(child_quota) <= parent_quota, inherit when no
8251 if (quota
== RUNTIME_INF
)
8252 quota
= parent_quota
;
8253 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
8256 cfs_b
->hierarchical_quota
= quota
;
8261 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
8264 struct cfs_schedulable_data data
= {
8270 if (quota
!= RUNTIME_INF
) {
8271 do_div(data
.period
, NSEC_PER_USEC
);
8272 do_div(data
.quota
, NSEC_PER_USEC
);
8276 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
8282 static int cpu_stats_show(struct seq_file
*sf
, void *v
)
8284 struct task_group
*tg
= css_tg(seq_css(sf
));
8285 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8287 seq_printf(sf
, "nr_periods %d\n", cfs_b
->nr_periods
);
8288 seq_printf(sf
, "nr_throttled %d\n", cfs_b
->nr_throttled
);
8289 seq_printf(sf
, "throttled_time %llu\n", cfs_b
->throttled_time
);
8293 #endif /* CONFIG_CFS_BANDWIDTH */
8294 #endif /* CONFIG_FAIR_GROUP_SCHED */
8296 #ifdef CONFIG_RT_GROUP_SCHED
8297 static int cpu_rt_runtime_write(struct cgroup_subsys_state
*css
,
8298 struct cftype
*cft
, s64 val
)
8300 return sched_group_set_rt_runtime(css_tg(css
), val
);
8303 static s64
cpu_rt_runtime_read(struct cgroup_subsys_state
*css
,
8306 return sched_group_rt_runtime(css_tg(css
));
8309 static int cpu_rt_period_write_uint(struct cgroup_subsys_state
*css
,
8310 struct cftype
*cftype
, u64 rt_period_us
)
8312 return sched_group_set_rt_period(css_tg(css
), rt_period_us
);
8315 static u64
cpu_rt_period_read_uint(struct cgroup_subsys_state
*css
,
8318 return sched_group_rt_period(css_tg(css
));
8320 #endif /* CONFIG_RT_GROUP_SCHED */
8322 static struct cftype cpu_files
[] = {
8323 #ifdef CONFIG_FAIR_GROUP_SCHED
8326 .read_u64
= cpu_shares_read_u64
,
8327 .write_u64
= cpu_shares_write_u64
,
8330 #ifdef CONFIG_CFS_BANDWIDTH
8332 .name
= "cfs_quota_us",
8333 .read_s64
= cpu_cfs_quota_read_s64
,
8334 .write_s64
= cpu_cfs_quota_write_s64
,
8337 .name
= "cfs_period_us",
8338 .read_u64
= cpu_cfs_period_read_u64
,
8339 .write_u64
= cpu_cfs_period_write_u64
,
8343 .seq_show
= cpu_stats_show
,
8346 #ifdef CONFIG_RT_GROUP_SCHED
8348 .name
= "rt_runtime_us",
8349 .read_s64
= cpu_rt_runtime_read
,
8350 .write_s64
= cpu_rt_runtime_write
,
8353 .name
= "rt_period_us",
8354 .read_u64
= cpu_rt_period_read_uint
,
8355 .write_u64
= cpu_rt_period_write_uint
,
8361 struct cgroup_subsys cpu_cgrp_subsys
= {
8362 .css_alloc
= cpu_cgroup_css_alloc
,
8363 .css_free
= cpu_cgroup_css_free
,
8364 .css_online
= cpu_cgroup_css_online
,
8365 .css_offline
= cpu_cgroup_css_offline
,
8366 .fork
= cpu_cgroup_fork
,
8367 .can_attach
= cpu_cgroup_can_attach
,
8368 .attach
= cpu_cgroup_attach
,
8369 .exit
= cpu_cgroup_exit
,
8370 .legacy_cftypes
= cpu_files
,
8374 #endif /* CONFIG_CGROUP_SCHED */
8376 void dump_cpu_task(int cpu
)
8378 pr_info("Task dump for CPU %d:\n", cpu
);
8379 sched_show_task(cpu_curr(cpu
));