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
29 #include <linux/kasan.h>
31 #include <linux/module.h>
32 #include <linux/nmi.h>
33 #include <linux/init.h>
34 #include <linux/uaccess.h>
35 #include <linux/highmem.h>
36 #include <asm/mmu_context.h>
37 #include <linux/interrupt.h>
38 #include <linux/capability.h>
39 #include <linux/completion.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/debug_locks.h>
42 #include <linux/perf_event.h>
43 #include <linux/security.h>
44 #include <linux/notifier.h>
45 #include <linux/profile.h>
46 #include <linux/freezer.h>
47 #include <linux/vmalloc.h>
48 #include <linux/blkdev.h>
49 #include <linux/delay.h>
50 #include <linux/pid_namespace.h>
51 #include <linux/smp.h>
52 #include <linux/threads.h>
53 #include <linux/timer.h>
54 #include <linux/rcupdate.h>
55 #include <linux/cpu.h>
56 #include <linux/cpuset.h>
57 #include <linux/percpu.h>
58 #include <linux/proc_fs.h>
59 #include <linux/seq_file.h>
60 #include <linux/sysctl.h>
61 #include <linux/syscalls.h>
62 #include <linux/times.h>
63 #include <linux/tsacct_kern.h>
64 #include <linux/kprobes.h>
65 #include <linux/delayacct.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.h>
70 #include <linux/debugfs.h>
71 #include <linux/ctype.h>
72 #include <linux/ftrace.h>
73 #include <linux/slab.h>
74 #include <linux/init_task.h>
75 #include <linux/binfmts.h>
76 #include <linux/context_tracking.h>
77 #include <linux/compiler.h>
79 #include <asm/switch_to.h>
81 #include <asm/irq_regs.h>
82 #include <asm/mutex.h>
83 #ifdef CONFIG_PARAVIRT
84 #include <asm/paravirt.h>
88 #include "../workqueue_internal.h"
89 #include "../smpboot.h"
91 #define CREATE_TRACE_POINTS
92 #include <trace/events/sched.h>
94 DEFINE_MUTEX(sched_domains_mutex
);
95 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
97 static void update_rq_clock_task(struct rq
*rq
, s64 delta
);
99 void update_rq_clock(struct rq
*rq
)
103 lockdep_assert_held(&rq
->lock
);
105 if (rq
->clock_skip_update
& RQCF_ACT_SKIP
)
108 delta
= sched_clock_cpu(cpu_of(rq
)) - rq
->clock
;
112 update_rq_clock_task(rq
, delta
);
116 * Debugging: various feature bits
119 #define SCHED_FEAT(name, enabled) \
120 (1UL << __SCHED_FEAT_##name) * enabled |
122 const_debug
unsigned int sysctl_sched_features
=
123 #include "features.h"
128 #ifdef CONFIG_SCHED_DEBUG
129 #define SCHED_FEAT(name, enabled) \
132 static const char * const sched_feat_names
[] = {
133 #include "features.h"
138 static int sched_feat_show(struct seq_file
*m
, void *v
)
142 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
143 if (!(sysctl_sched_features
& (1UL << i
)))
145 seq_printf(m
, "%s ", sched_feat_names
[i
]);
152 #ifdef HAVE_JUMP_LABEL
154 #define jump_label_key__true STATIC_KEY_INIT_TRUE
155 #define jump_label_key__false STATIC_KEY_INIT_FALSE
157 #define SCHED_FEAT(name, enabled) \
158 jump_label_key__##enabled ,
160 struct static_key sched_feat_keys
[__SCHED_FEAT_NR
] = {
161 #include "features.h"
166 static void sched_feat_disable(int i
)
168 static_key_disable(&sched_feat_keys
[i
]);
171 static void sched_feat_enable(int i
)
173 static_key_enable(&sched_feat_keys
[i
]);
176 static void sched_feat_disable(int i
) { };
177 static void sched_feat_enable(int i
) { };
178 #endif /* HAVE_JUMP_LABEL */
180 static int sched_feat_set(char *cmp
)
185 if (strncmp(cmp
, "NO_", 3) == 0) {
190 for (i
= 0; i
< __SCHED_FEAT_NR
; i
++) {
191 if (strcmp(cmp
, sched_feat_names
[i
]) == 0) {
193 sysctl_sched_features
&= ~(1UL << i
);
194 sched_feat_disable(i
);
196 sysctl_sched_features
|= (1UL << i
);
197 sched_feat_enable(i
);
207 sched_feat_write(struct file
*filp
, const char __user
*ubuf
,
208 size_t cnt
, loff_t
*ppos
)
218 if (copy_from_user(&buf
, ubuf
, cnt
))
224 /* Ensure the static_key remains in a consistent state */
225 inode
= file_inode(filp
);
227 i
= sched_feat_set(cmp
);
229 if (i
== __SCHED_FEAT_NR
)
237 static int sched_feat_open(struct inode
*inode
, struct file
*filp
)
239 return single_open(filp
, sched_feat_show
, NULL
);
242 static const struct file_operations sched_feat_fops
= {
243 .open
= sched_feat_open
,
244 .write
= sched_feat_write
,
247 .release
= single_release
,
250 static __init
int sched_init_debug(void)
252 debugfs_create_file("sched_features", 0644, NULL
, NULL
,
257 late_initcall(sched_init_debug
);
258 #endif /* CONFIG_SCHED_DEBUG */
261 * Number of tasks to iterate in a single balance run.
262 * Limited because this is done with IRQs disabled.
264 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
267 * period over which we average the RT time consumption, measured
272 const_debug
unsigned int sysctl_sched_time_avg
= MSEC_PER_SEC
;
275 * period over which we measure -rt task cpu usage in us.
278 unsigned int sysctl_sched_rt_period
= 1000000;
280 __read_mostly
int scheduler_running
;
283 * part of the period that we allow rt tasks to run in us.
286 int sysctl_sched_rt_runtime
= 950000;
288 /* cpus with isolated domains */
289 cpumask_var_t cpu_isolated_map
;
292 * this_rq_lock - lock this runqueue and disable interrupts.
294 static struct rq
*this_rq_lock(void)
301 raw_spin_lock(&rq
->lock
);
306 #ifdef CONFIG_SCHED_HRTICK
308 * Use HR-timers to deliver accurate preemption points.
311 static void hrtick_clear(struct rq
*rq
)
313 if (hrtimer_active(&rq
->hrtick_timer
))
314 hrtimer_cancel(&rq
->hrtick_timer
);
318 * High-resolution timer tick.
319 * Runs from hardirq context with interrupts disabled.
321 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
323 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
325 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
327 raw_spin_lock(&rq
->lock
);
329 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
330 raw_spin_unlock(&rq
->lock
);
332 return HRTIMER_NORESTART
;
337 static void __hrtick_restart(struct rq
*rq
)
339 struct hrtimer
*timer
= &rq
->hrtick_timer
;
341 hrtimer_start_expires(timer
, HRTIMER_MODE_ABS_PINNED
);
345 * called from hardirq (IPI) context
347 static void __hrtick_start(void *arg
)
351 raw_spin_lock(&rq
->lock
);
352 __hrtick_restart(rq
);
353 rq
->hrtick_csd_pending
= 0;
354 raw_spin_unlock(&rq
->lock
);
358 * Called to set the hrtick timer state.
360 * called with rq->lock held and irqs disabled
362 void hrtick_start(struct rq
*rq
, u64 delay
)
364 struct hrtimer
*timer
= &rq
->hrtick_timer
;
369 * Don't schedule slices shorter than 10000ns, that just
370 * doesn't make sense and can cause timer DoS.
372 delta
= max_t(s64
, delay
, 10000LL);
373 time
= ktime_add_ns(timer
->base
->get_time(), delta
);
375 hrtimer_set_expires(timer
, time
);
377 if (rq
== this_rq()) {
378 __hrtick_restart(rq
);
379 } else if (!rq
->hrtick_csd_pending
) {
380 smp_call_function_single_async(cpu_of(rq
), &rq
->hrtick_csd
);
381 rq
->hrtick_csd_pending
= 1;
386 hotplug_hrtick(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
388 int cpu
= (int)(long)hcpu
;
391 case CPU_UP_CANCELED
:
392 case CPU_UP_CANCELED_FROZEN
:
393 case CPU_DOWN_PREPARE
:
394 case CPU_DOWN_PREPARE_FROZEN
:
396 case CPU_DEAD_FROZEN
:
397 hrtick_clear(cpu_rq(cpu
));
404 static __init
void init_hrtick(void)
406 hotcpu_notifier(hotplug_hrtick
, 0);
410 * Called to set the hrtick timer state.
412 * called with rq->lock held and irqs disabled
414 void hrtick_start(struct rq
*rq
, u64 delay
)
417 * Don't schedule slices shorter than 10000ns, that just
418 * doesn't make sense. Rely on vruntime for fairness.
420 delay
= max_t(u64
, delay
, 10000LL);
421 hrtimer_start(&rq
->hrtick_timer
, ns_to_ktime(delay
),
422 HRTIMER_MODE_REL_PINNED
);
425 static inline void init_hrtick(void)
428 #endif /* CONFIG_SMP */
430 static void init_rq_hrtick(struct rq
*rq
)
433 rq
->hrtick_csd_pending
= 0;
435 rq
->hrtick_csd
.flags
= 0;
436 rq
->hrtick_csd
.func
= __hrtick_start
;
437 rq
->hrtick_csd
.info
= rq
;
440 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
441 rq
->hrtick_timer
.function
= hrtick
;
443 #else /* CONFIG_SCHED_HRTICK */
444 static inline void hrtick_clear(struct rq
*rq
)
448 static inline void init_rq_hrtick(struct rq
*rq
)
452 static inline void init_hrtick(void)
455 #endif /* CONFIG_SCHED_HRTICK */
458 * cmpxchg based fetch_or, macro so it works for different integer types
460 #define fetch_or(ptr, val) \
461 ({ typeof(*(ptr)) __old, __val = *(ptr); \
463 __old = cmpxchg((ptr), __val, __val | (val)); \
464 if (__old == __val) \
471 #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
473 * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
474 * this avoids any races wrt polling state changes and thereby avoids
477 static bool set_nr_and_not_polling(struct task_struct
*p
)
479 struct thread_info
*ti
= task_thread_info(p
);
480 return !(fetch_or(&ti
->flags
, _TIF_NEED_RESCHED
) & _TIF_POLLING_NRFLAG
);
484 * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
486 * If this returns true, then the idle task promises to call
487 * sched_ttwu_pending() and reschedule soon.
489 static bool set_nr_if_polling(struct task_struct
*p
)
491 struct thread_info
*ti
= task_thread_info(p
);
492 typeof(ti
->flags
) old
, val
= READ_ONCE(ti
->flags
);
495 if (!(val
& _TIF_POLLING_NRFLAG
))
497 if (val
& _TIF_NEED_RESCHED
)
499 old
= cmpxchg(&ti
->flags
, val
, val
| _TIF_NEED_RESCHED
);
508 static bool set_nr_and_not_polling(struct task_struct
*p
)
510 set_tsk_need_resched(p
);
515 static bool set_nr_if_polling(struct task_struct
*p
)
522 void wake_q_add(struct wake_q_head
*head
, struct task_struct
*task
)
524 struct wake_q_node
*node
= &task
->wake_q
;
527 * Atomically grab the task, if ->wake_q is !nil already it means
528 * its already queued (either by us or someone else) and will get the
529 * wakeup due to that.
531 * This cmpxchg() implies a full barrier, which pairs with the write
532 * barrier implied by the wakeup in wake_up_list().
534 if (cmpxchg(&node
->next
, NULL
, WAKE_Q_TAIL
))
537 get_task_struct(task
);
540 * The head is context local, there can be no concurrency.
543 head
->lastp
= &node
->next
;
546 void wake_up_q(struct wake_q_head
*head
)
548 struct wake_q_node
*node
= head
->first
;
550 while (node
!= WAKE_Q_TAIL
) {
551 struct task_struct
*task
;
553 task
= container_of(node
, struct task_struct
, wake_q
);
555 /* task can safely be re-inserted now */
557 task
->wake_q
.next
= NULL
;
560 * wake_up_process() implies a wmb() to pair with the queueing
561 * in wake_q_add() so as not to miss wakeups.
563 wake_up_process(task
);
564 put_task_struct(task
);
569 * resched_curr - mark rq's current task 'to be rescheduled now'.
571 * On UP this means the setting of the need_resched flag, on SMP it
572 * might also involve a cross-CPU call to trigger the scheduler on
575 void resched_curr(struct rq
*rq
)
577 struct task_struct
*curr
= rq
->curr
;
580 lockdep_assert_held(&rq
->lock
);
582 if (test_tsk_need_resched(curr
))
587 if (cpu
== smp_processor_id()) {
588 set_tsk_need_resched(curr
);
589 set_preempt_need_resched();
593 if (set_nr_and_not_polling(curr
))
594 smp_send_reschedule(cpu
);
596 trace_sched_wake_idle_without_ipi(cpu
);
599 void resched_cpu(int cpu
)
601 struct rq
*rq
= cpu_rq(cpu
);
604 if (!raw_spin_trylock_irqsave(&rq
->lock
, flags
))
607 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
611 #ifdef CONFIG_NO_HZ_COMMON
613 * In the semi idle case, use the nearest busy cpu for migrating timers
614 * from an idle cpu. This is good for power-savings.
616 * We don't do similar optimization for completely idle system, as
617 * selecting an idle cpu will add more delays to the timers than intended
618 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
620 int get_nohz_timer_target(void)
622 int i
, cpu
= smp_processor_id();
623 struct sched_domain
*sd
;
625 if (!idle_cpu(cpu
) && is_housekeeping_cpu(cpu
))
629 for_each_domain(cpu
, sd
) {
630 for_each_cpu(i
, sched_domain_span(sd
)) {
631 if (!idle_cpu(i
) && is_housekeeping_cpu(cpu
)) {
638 if (!is_housekeeping_cpu(cpu
))
639 cpu
= housekeeping_any_cpu();
645 * When add_timer_on() enqueues a timer into the timer wheel of an
646 * idle CPU then this timer might expire before the next timer event
647 * which is scheduled to wake up that CPU. In case of a completely
648 * idle system the next event might even be infinite time into the
649 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
650 * leaves the inner idle loop so the newly added timer is taken into
651 * account when the CPU goes back to idle and evaluates the timer
652 * wheel for the next timer event.
654 static void wake_up_idle_cpu(int cpu
)
656 struct rq
*rq
= cpu_rq(cpu
);
658 if (cpu
== smp_processor_id())
661 if (set_nr_and_not_polling(rq
->idle
))
662 smp_send_reschedule(cpu
);
664 trace_sched_wake_idle_without_ipi(cpu
);
667 static bool wake_up_full_nohz_cpu(int cpu
)
670 * We just need the target to call irq_exit() and re-evaluate
671 * the next tick. The nohz full kick at least implies that.
672 * If needed we can still optimize that later with an
675 if (tick_nohz_full_cpu(cpu
)) {
676 if (cpu
!= smp_processor_id() ||
677 tick_nohz_tick_stopped())
678 tick_nohz_full_kick_cpu(cpu
);
685 void wake_up_nohz_cpu(int cpu
)
687 if (!wake_up_full_nohz_cpu(cpu
))
688 wake_up_idle_cpu(cpu
);
691 static inline bool got_nohz_idle_kick(void)
693 int cpu
= smp_processor_id();
695 if (!test_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
)))
698 if (idle_cpu(cpu
) && !need_resched())
702 * We can't run Idle Load Balance on this CPU for this time so we
703 * cancel it and clear NOHZ_BALANCE_KICK
705 clear_bit(NOHZ_BALANCE_KICK
, nohz_flags(cpu
));
709 #else /* CONFIG_NO_HZ_COMMON */
711 static inline bool got_nohz_idle_kick(void)
716 #endif /* CONFIG_NO_HZ_COMMON */
718 #ifdef CONFIG_NO_HZ_FULL
719 bool sched_can_stop_tick(void)
722 * FIFO realtime policy runs the highest priority task. Other runnable
723 * tasks are of a lower priority. The scheduler tick does nothing.
725 if (current
->policy
== SCHED_FIFO
)
729 * Round-robin realtime tasks time slice with other tasks at the same
730 * realtime priority. Is this task the only one at this priority?
732 if (current
->policy
== SCHED_RR
) {
733 struct sched_rt_entity
*rt_se
= ¤t
->rt
;
735 return list_is_singular(&rt_se
->run_list
);
739 * More than one running task need preemption.
740 * nr_running update is assumed to be visible
741 * after IPI is sent from wakers.
743 if (this_rq()->nr_running
> 1)
748 #endif /* CONFIG_NO_HZ_FULL */
750 void sched_avg_update(struct rq
*rq
)
752 s64 period
= sched_avg_period();
754 while ((s64
)(rq_clock(rq
) - rq
->age_stamp
) > period
) {
756 * Inline assembly required to prevent the compiler
757 * optimising this loop into a divmod call.
758 * See __iter_div_u64_rem() for another example of this.
760 asm("" : "+rm" (rq
->age_stamp
));
761 rq
->age_stamp
+= period
;
766 #endif /* CONFIG_SMP */
768 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
769 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
771 * Iterate task_group tree rooted at *from, calling @down when first entering a
772 * node and @up when leaving it for the final time.
774 * Caller must hold rcu_lock or sufficient equivalent.
776 int walk_tg_tree_from(struct task_group
*from
,
777 tg_visitor down
, tg_visitor up
, void *data
)
779 struct task_group
*parent
, *child
;
785 ret
= (*down
)(parent
, data
);
788 list_for_each_entry_rcu(child
, &parent
->children
, siblings
) {
795 ret
= (*up
)(parent
, data
);
796 if (ret
|| parent
== from
)
800 parent
= parent
->parent
;
807 int tg_nop(struct task_group
*tg
, void *data
)
813 static void set_load_weight(struct task_struct
*p
)
815 int prio
= p
->static_prio
- MAX_RT_PRIO
;
816 struct load_weight
*load
= &p
->se
.load
;
819 * SCHED_IDLE tasks get minimal weight:
821 if (idle_policy(p
->policy
)) {
822 load
->weight
= scale_load(WEIGHT_IDLEPRIO
);
823 load
->inv_weight
= WMULT_IDLEPRIO
;
827 load
->weight
= scale_load(sched_prio_to_weight
[prio
]);
828 load
->inv_weight
= sched_prio_to_wmult
[prio
];
831 static inline void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
834 if (!(flags
& ENQUEUE_RESTORE
))
835 sched_info_queued(rq
, p
);
836 p
->sched_class
->enqueue_task(rq
, p
, flags
);
839 static inline void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
842 if (!(flags
& DEQUEUE_SAVE
))
843 sched_info_dequeued(rq
, p
);
844 p
->sched_class
->dequeue_task(rq
, p
, flags
);
847 void activate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
849 if (task_contributes_to_load(p
))
850 rq
->nr_uninterruptible
--;
852 enqueue_task(rq
, p
, flags
);
855 void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int flags
)
857 if (task_contributes_to_load(p
))
858 rq
->nr_uninterruptible
++;
860 dequeue_task(rq
, p
, flags
);
863 static void update_rq_clock_task(struct rq
*rq
, s64 delta
)
866 * In theory, the compile should just see 0 here, and optimize out the call
867 * to sched_rt_avg_update. But I don't trust it...
869 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
870 s64 steal
= 0, irq_delta
= 0;
872 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
873 irq_delta
= irq_time_read(cpu_of(rq
)) - rq
->prev_irq_time
;
876 * Since irq_time is only updated on {soft,}irq_exit, we might run into
877 * this case when a previous update_rq_clock() happened inside a
880 * When this happens, we stop ->clock_task and only update the
881 * prev_irq_time stamp to account for the part that fit, so that a next
882 * update will consume the rest. This ensures ->clock_task is
885 * It does however cause some slight miss-attribution of {soft,}irq
886 * time, a more accurate solution would be to update the irq_time using
887 * the current rq->clock timestamp, except that would require using
890 if (irq_delta
> delta
)
893 rq
->prev_irq_time
+= irq_delta
;
896 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
897 if (static_key_false((¶virt_steal_rq_enabled
))) {
898 steal
= paravirt_steal_clock(cpu_of(rq
));
899 steal
-= rq
->prev_steal_time_rq
;
901 if (unlikely(steal
> delta
))
904 rq
->prev_steal_time_rq
+= steal
;
909 rq
->clock_task
+= delta
;
911 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
912 if ((irq_delta
+ steal
) && sched_feat(NONTASK_CAPACITY
))
913 sched_rt_avg_update(rq
, irq_delta
+ steal
);
917 void sched_set_stop_task(int cpu
, struct task_struct
*stop
)
919 struct sched_param param
= { .sched_priority
= MAX_RT_PRIO
- 1 };
920 struct task_struct
*old_stop
= cpu_rq(cpu
)->stop
;
924 * Make it appear like a SCHED_FIFO task, its something
925 * userspace knows about and won't get confused about.
927 * Also, it will make PI more or less work without too
928 * much confusion -- but then, stop work should not
929 * rely on PI working anyway.
931 sched_setscheduler_nocheck(stop
, SCHED_FIFO
, ¶m
);
933 stop
->sched_class
= &stop_sched_class
;
936 cpu_rq(cpu
)->stop
= stop
;
940 * Reset it back to a normal scheduling class so that
941 * it can die in pieces.
943 old_stop
->sched_class
= &rt_sched_class
;
948 * __normal_prio - return the priority that is based on the static prio
950 static inline int __normal_prio(struct task_struct
*p
)
952 return p
->static_prio
;
956 * Calculate the expected normal priority: i.e. priority
957 * without taking RT-inheritance into account. Might be
958 * boosted by interactivity modifiers. Changes upon fork,
959 * setprio syscalls, and whenever the interactivity
960 * estimator recalculates.
962 static inline int normal_prio(struct task_struct
*p
)
966 if (task_has_dl_policy(p
))
967 prio
= MAX_DL_PRIO
-1;
968 else if (task_has_rt_policy(p
))
969 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
971 prio
= __normal_prio(p
);
976 * Calculate the current priority, i.e. the priority
977 * taken into account by the scheduler. This value might
978 * be boosted by RT tasks, or might be boosted by
979 * interactivity modifiers. Will be RT if the task got
980 * RT-boosted. If not then it returns p->normal_prio.
982 static int effective_prio(struct task_struct
*p
)
984 p
->normal_prio
= normal_prio(p
);
986 * If we are RT tasks or we were boosted to RT priority,
987 * keep the priority unchanged. Otherwise, update priority
988 * to the normal priority:
990 if (!rt_prio(p
->prio
))
991 return p
->normal_prio
;
996 * task_curr - is this task currently executing on a CPU?
997 * @p: the task in question.
999 * Return: 1 if the task is currently executing. 0 otherwise.
1001 inline int task_curr(const struct task_struct
*p
)
1003 return cpu_curr(task_cpu(p
)) == p
;
1007 * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
1008 * use the balance_callback list if you want balancing.
1010 * this means any call to check_class_changed() must be followed by a call to
1011 * balance_callback().
1013 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
1014 const struct sched_class
*prev_class
,
1017 if (prev_class
!= p
->sched_class
) {
1018 if (prev_class
->switched_from
)
1019 prev_class
->switched_from(rq
, p
);
1021 p
->sched_class
->switched_to(rq
, p
);
1022 } else if (oldprio
!= p
->prio
|| dl_task(p
))
1023 p
->sched_class
->prio_changed(rq
, p
, oldprio
);
1026 void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
, int flags
)
1028 const struct sched_class
*class;
1030 if (p
->sched_class
== rq
->curr
->sched_class
) {
1031 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
, flags
);
1033 for_each_class(class) {
1034 if (class == rq
->curr
->sched_class
)
1036 if (class == p
->sched_class
) {
1044 * A queue event has occurred, and we're going to schedule. In
1045 * this case, we can save a useless back to back clock update.
1047 if (task_on_rq_queued(rq
->curr
) && test_tsk_need_resched(rq
->curr
))
1048 rq_clock_skip_update(rq
, true);
1053 * This is how migration works:
1055 * 1) we invoke migration_cpu_stop() on the target CPU using
1057 * 2) stopper starts to run (implicitly forcing the migrated thread
1059 * 3) it checks whether the migrated task is still in the wrong runqueue.
1060 * 4) if it's in the wrong runqueue then the migration thread removes
1061 * it and puts it into the right queue.
1062 * 5) stopper completes and stop_one_cpu() returns and the migration
1067 * move_queued_task - move a queued task to new rq.
1069 * Returns (locked) new rq. Old rq's lock is released.
1071 static struct rq
*move_queued_task(struct rq
*rq
, struct task_struct
*p
, int new_cpu
)
1073 lockdep_assert_held(&rq
->lock
);
1075 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
1076 dequeue_task(rq
, p
, 0);
1077 set_task_cpu(p
, new_cpu
);
1078 raw_spin_unlock(&rq
->lock
);
1080 rq
= cpu_rq(new_cpu
);
1082 raw_spin_lock(&rq
->lock
);
1083 BUG_ON(task_cpu(p
) != new_cpu
);
1084 enqueue_task(rq
, p
, 0);
1085 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1086 check_preempt_curr(rq
, p
, 0);
1091 struct migration_arg
{
1092 struct task_struct
*task
;
1097 * Move (not current) task off this cpu, onto dest cpu. We're doing
1098 * this because either it can't run here any more (set_cpus_allowed()
1099 * away from this CPU, or CPU going down), or because we're
1100 * attempting to rebalance this task on exec (sched_exec).
1102 * So we race with normal scheduler movements, but that's OK, as long
1103 * as the task is no longer on this CPU.
1105 static struct rq
*__migrate_task(struct rq
*rq
, struct task_struct
*p
, int dest_cpu
)
1107 if (unlikely(!cpu_active(dest_cpu
)))
1110 /* Affinity changed (again). */
1111 if (!cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1114 rq
= move_queued_task(rq
, p
, dest_cpu
);
1120 * migration_cpu_stop - this will be executed by a highprio stopper thread
1121 * and performs thread migration by bumping thread off CPU then
1122 * 'pushing' onto another runqueue.
1124 static int migration_cpu_stop(void *data
)
1126 struct migration_arg
*arg
= data
;
1127 struct task_struct
*p
= arg
->task
;
1128 struct rq
*rq
= this_rq();
1131 * The original target cpu might have gone down and we might
1132 * be on another cpu but it doesn't matter.
1134 local_irq_disable();
1136 * We need to explicitly wake pending tasks before running
1137 * __migrate_task() such that we will not miss enforcing cpus_allowed
1138 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
1140 sched_ttwu_pending();
1142 raw_spin_lock(&p
->pi_lock
);
1143 raw_spin_lock(&rq
->lock
);
1145 * If task_rq(p) != rq, it cannot be migrated here, because we're
1146 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
1147 * we're holding p->pi_lock.
1149 if (task_rq(p
) == rq
&& task_on_rq_queued(p
))
1150 rq
= __migrate_task(rq
, p
, arg
->dest_cpu
);
1151 raw_spin_unlock(&rq
->lock
);
1152 raw_spin_unlock(&p
->pi_lock
);
1159 * sched_class::set_cpus_allowed must do the below, but is not required to
1160 * actually call this function.
1162 void set_cpus_allowed_common(struct task_struct
*p
, const struct cpumask
*new_mask
)
1164 cpumask_copy(&p
->cpus_allowed
, new_mask
);
1165 p
->nr_cpus_allowed
= cpumask_weight(new_mask
);
1168 void do_set_cpus_allowed(struct task_struct
*p
, const struct cpumask
*new_mask
)
1170 struct rq
*rq
= task_rq(p
);
1171 bool queued
, running
;
1173 lockdep_assert_held(&p
->pi_lock
);
1175 queued
= task_on_rq_queued(p
);
1176 running
= task_current(rq
, p
);
1180 * Because __kthread_bind() calls this on blocked tasks without
1183 lockdep_assert_held(&rq
->lock
);
1184 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
1187 put_prev_task(rq
, p
);
1189 p
->sched_class
->set_cpus_allowed(p
, new_mask
);
1192 p
->sched_class
->set_curr_task(rq
);
1194 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
1198 * Change a given task's CPU affinity. Migrate the thread to a
1199 * proper CPU and schedule it away if the CPU it's executing on
1200 * is removed from the allowed bitmask.
1202 * NOTE: the caller must have a valid reference to the task, the
1203 * task must not exit() & deallocate itself prematurely. The
1204 * call is not atomic; no spinlocks may be held.
1206 static int __set_cpus_allowed_ptr(struct task_struct
*p
,
1207 const struct cpumask
*new_mask
, bool check
)
1209 unsigned long flags
;
1211 unsigned int dest_cpu
;
1214 rq
= task_rq_lock(p
, &flags
);
1217 * Must re-check here, to close a race against __kthread_bind(),
1218 * sched_setaffinity() is not guaranteed to observe the flag.
1220 if (check
&& (p
->flags
& PF_NO_SETAFFINITY
)) {
1225 if (cpumask_equal(&p
->cpus_allowed
, new_mask
))
1228 if (!cpumask_intersects(new_mask
, cpu_active_mask
)) {
1233 do_set_cpus_allowed(p
, new_mask
);
1235 /* Can the task run on the task's current CPU? If so, we're done */
1236 if (cpumask_test_cpu(task_cpu(p
), new_mask
))
1239 dest_cpu
= cpumask_any_and(cpu_active_mask
, new_mask
);
1240 if (task_running(rq
, p
) || p
->state
== TASK_WAKING
) {
1241 struct migration_arg arg
= { p
, dest_cpu
};
1242 /* Need help from migration thread: drop lock and wait. */
1243 task_rq_unlock(rq
, p
, &flags
);
1244 stop_one_cpu(cpu_of(rq
), migration_cpu_stop
, &arg
);
1245 tlb_migrate_finish(p
->mm
);
1247 } else if (task_on_rq_queued(p
)) {
1249 * OK, since we're going to drop the lock immediately
1250 * afterwards anyway.
1252 lockdep_unpin_lock(&rq
->lock
);
1253 rq
= move_queued_task(rq
, p
, dest_cpu
);
1254 lockdep_pin_lock(&rq
->lock
);
1257 task_rq_unlock(rq
, p
, &flags
);
1262 int set_cpus_allowed_ptr(struct task_struct
*p
, const struct cpumask
*new_mask
)
1264 return __set_cpus_allowed_ptr(p
, new_mask
, false);
1266 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr
);
1268 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1270 #ifdef CONFIG_SCHED_DEBUG
1272 * We should never call set_task_cpu() on a blocked task,
1273 * ttwu() will sort out the placement.
1275 WARN_ON_ONCE(p
->state
!= TASK_RUNNING
&& p
->state
!= TASK_WAKING
&&
1279 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
1280 * because schedstat_wait_{start,end} rebase migrating task's wait_start
1281 * time relying on p->on_rq.
1283 WARN_ON_ONCE(p
->state
== TASK_RUNNING
&&
1284 p
->sched_class
== &fair_sched_class
&&
1285 (p
->on_rq
&& !task_on_rq_migrating(p
)));
1287 #ifdef CONFIG_LOCKDEP
1289 * The caller should hold either p->pi_lock or rq->lock, when changing
1290 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1292 * sched_move_task() holds both and thus holding either pins the cgroup,
1295 * Furthermore, all task_rq users should acquire both locks, see
1298 WARN_ON_ONCE(debug_locks
&& !(lockdep_is_held(&p
->pi_lock
) ||
1299 lockdep_is_held(&task_rq(p
)->lock
)));
1303 trace_sched_migrate_task(p
, new_cpu
);
1305 if (task_cpu(p
) != new_cpu
) {
1306 if (p
->sched_class
->migrate_task_rq
)
1307 p
->sched_class
->migrate_task_rq(p
);
1308 p
->se
.nr_migrations
++;
1309 perf_event_task_migrate(p
);
1312 __set_task_cpu(p
, new_cpu
);
1315 static void __migrate_swap_task(struct task_struct
*p
, int cpu
)
1317 if (task_on_rq_queued(p
)) {
1318 struct rq
*src_rq
, *dst_rq
;
1320 src_rq
= task_rq(p
);
1321 dst_rq
= cpu_rq(cpu
);
1323 p
->on_rq
= TASK_ON_RQ_MIGRATING
;
1324 deactivate_task(src_rq
, p
, 0);
1325 set_task_cpu(p
, cpu
);
1326 activate_task(dst_rq
, p
, 0);
1327 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1328 check_preempt_curr(dst_rq
, p
, 0);
1331 * Task isn't running anymore; make it appear like we migrated
1332 * it before it went to sleep. This means on wakeup we make the
1333 * previous cpu our targer instead of where it really is.
1339 struct migration_swap_arg
{
1340 struct task_struct
*src_task
, *dst_task
;
1341 int src_cpu
, dst_cpu
;
1344 static int migrate_swap_stop(void *data
)
1346 struct migration_swap_arg
*arg
= data
;
1347 struct rq
*src_rq
, *dst_rq
;
1350 if (!cpu_active(arg
->src_cpu
) || !cpu_active(arg
->dst_cpu
))
1353 src_rq
= cpu_rq(arg
->src_cpu
);
1354 dst_rq
= cpu_rq(arg
->dst_cpu
);
1356 double_raw_lock(&arg
->src_task
->pi_lock
,
1357 &arg
->dst_task
->pi_lock
);
1358 double_rq_lock(src_rq
, dst_rq
);
1360 if (task_cpu(arg
->dst_task
) != arg
->dst_cpu
)
1363 if (task_cpu(arg
->src_task
) != arg
->src_cpu
)
1366 if (!cpumask_test_cpu(arg
->dst_cpu
, tsk_cpus_allowed(arg
->src_task
)))
1369 if (!cpumask_test_cpu(arg
->src_cpu
, tsk_cpus_allowed(arg
->dst_task
)))
1372 __migrate_swap_task(arg
->src_task
, arg
->dst_cpu
);
1373 __migrate_swap_task(arg
->dst_task
, arg
->src_cpu
);
1378 double_rq_unlock(src_rq
, dst_rq
);
1379 raw_spin_unlock(&arg
->dst_task
->pi_lock
);
1380 raw_spin_unlock(&arg
->src_task
->pi_lock
);
1386 * Cross migrate two tasks
1388 int migrate_swap(struct task_struct
*cur
, struct task_struct
*p
)
1390 struct migration_swap_arg arg
;
1393 arg
= (struct migration_swap_arg
){
1395 .src_cpu
= task_cpu(cur
),
1397 .dst_cpu
= task_cpu(p
),
1400 if (arg
.src_cpu
== arg
.dst_cpu
)
1404 * These three tests are all lockless; this is OK since all of them
1405 * will be re-checked with proper locks held further down the line.
1407 if (!cpu_active(arg
.src_cpu
) || !cpu_active(arg
.dst_cpu
))
1410 if (!cpumask_test_cpu(arg
.dst_cpu
, tsk_cpus_allowed(arg
.src_task
)))
1413 if (!cpumask_test_cpu(arg
.src_cpu
, tsk_cpus_allowed(arg
.dst_task
)))
1416 trace_sched_swap_numa(cur
, arg
.src_cpu
, p
, arg
.dst_cpu
);
1417 ret
= stop_two_cpus(arg
.dst_cpu
, arg
.src_cpu
, migrate_swap_stop
, &arg
);
1424 * wait_task_inactive - wait for a thread to unschedule.
1426 * If @match_state is nonzero, it's the @p->state value just checked and
1427 * not expected to change. If it changes, i.e. @p might have woken up,
1428 * then return zero. When we succeed in waiting for @p to be off its CPU,
1429 * we return a positive number (its total switch count). If a second call
1430 * a short while later returns the same number, the caller can be sure that
1431 * @p has remained unscheduled the whole time.
1433 * The caller must ensure that the task *will* unschedule sometime soon,
1434 * else this function might spin for a *long* time. This function can't
1435 * be called with interrupts off, or it may introduce deadlock with
1436 * smp_call_function() if an IPI is sent by the same process we are
1437 * waiting to become inactive.
1439 unsigned long wait_task_inactive(struct task_struct
*p
, long match_state
)
1441 unsigned long flags
;
1442 int running
, queued
;
1448 * We do the initial early heuristics without holding
1449 * any task-queue locks at all. We'll only try to get
1450 * the runqueue lock when things look like they will
1456 * If the task is actively running on another CPU
1457 * still, just relax and busy-wait without holding
1460 * NOTE! Since we don't hold any locks, it's not
1461 * even sure that "rq" stays as the right runqueue!
1462 * But we don't care, since "task_running()" will
1463 * return false if the runqueue has changed and p
1464 * is actually now running somewhere else!
1466 while (task_running(rq
, p
)) {
1467 if (match_state
&& unlikely(p
->state
!= match_state
))
1473 * Ok, time to look more closely! We need the rq
1474 * lock now, to be *sure*. If we're wrong, we'll
1475 * just go back and repeat.
1477 rq
= task_rq_lock(p
, &flags
);
1478 trace_sched_wait_task(p
);
1479 running
= task_running(rq
, p
);
1480 queued
= task_on_rq_queued(p
);
1482 if (!match_state
|| p
->state
== match_state
)
1483 ncsw
= p
->nvcsw
| LONG_MIN
; /* sets MSB */
1484 task_rq_unlock(rq
, p
, &flags
);
1487 * If it changed from the expected state, bail out now.
1489 if (unlikely(!ncsw
))
1493 * Was it really running after all now that we
1494 * checked with the proper locks actually held?
1496 * Oops. Go back and try again..
1498 if (unlikely(running
)) {
1504 * It's not enough that it's not actively running,
1505 * it must be off the runqueue _entirely_, and not
1508 * So if it was still runnable (but just not actively
1509 * running right now), it's preempted, and we should
1510 * yield - it could be a while.
1512 if (unlikely(queued
)) {
1513 ktime_t to
= ktime_set(0, NSEC_PER_SEC
/HZ
);
1515 set_current_state(TASK_UNINTERRUPTIBLE
);
1516 schedule_hrtimeout(&to
, HRTIMER_MODE_REL
);
1521 * Ahh, all good. It wasn't running, and it wasn't
1522 * runnable, which means that it will never become
1523 * running in the future either. We're all done!
1532 * kick_process - kick a running thread to enter/exit the kernel
1533 * @p: the to-be-kicked thread
1535 * Cause a process which is running on another CPU to enter
1536 * kernel-mode, without any delay. (to get signals handled.)
1538 * NOTE: this function doesn't have to take the runqueue lock,
1539 * because all it wants to ensure is that the remote task enters
1540 * the kernel. If the IPI races and the task has been migrated
1541 * to another CPU then no harm is done and the purpose has been
1544 void kick_process(struct task_struct
*p
)
1550 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1551 smp_send_reschedule(cpu
);
1554 EXPORT_SYMBOL_GPL(kick_process
);
1557 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1559 static int select_fallback_rq(int cpu
, struct task_struct
*p
)
1561 int nid
= cpu_to_node(cpu
);
1562 const struct cpumask
*nodemask
= NULL
;
1563 enum { cpuset
, possible
, fail
} state
= cpuset
;
1567 * If the node that the cpu is on has been offlined, cpu_to_node()
1568 * will return -1. There is no cpu on the node, and we should
1569 * select the cpu on the other node.
1572 nodemask
= cpumask_of_node(nid
);
1574 /* Look for allowed, online CPU in same node. */
1575 for_each_cpu(dest_cpu
, nodemask
) {
1576 if (!cpu_online(dest_cpu
))
1578 if (!cpu_active(dest_cpu
))
1580 if (cpumask_test_cpu(dest_cpu
, tsk_cpus_allowed(p
)))
1586 /* Any allowed, online CPU? */
1587 for_each_cpu(dest_cpu
, tsk_cpus_allowed(p
)) {
1588 if (!cpu_online(dest_cpu
))
1590 if (!cpu_active(dest_cpu
))
1595 /* No more Mr. Nice Guy. */
1598 if (IS_ENABLED(CONFIG_CPUSETS
)) {
1599 cpuset_cpus_allowed_fallback(p
);
1605 do_set_cpus_allowed(p
, cpu_possible_mask
);
1616 if (state
!= cpuset
) {
1618 * Don't tell them about moving exiting tasks or
1619 * kernel threads (both mm NULL), since they never
1622 if (p
->mm
&& printk_ratelimit()) {
1623 printk_deferred("process %d (%s) no longer affine to cpu%d\n",
1624 task_pid_nr(p
), p
->comm
, cpu
);
1632 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1635 int select_task_rq(struct task_struct
*p
, int cpu
, int sd_flags
, int wake_flags
)
1637 lockdep_assert_held(&p
->pi_lock
);
1639 if (p
->nr_cpus_allowed
> 1)
1640 cpu
= p
->sched_class
->select_task_rq(p
, cpu
, sd_flags
, wake_flags
);
1643 * In order not to call set_task_cpu() on a blocking task we need
1644 * to rely on ttwu() to place the task on a valid ->cpus_allowed
1647 * Since this is common to all placement strategies, this lives here.
1649 * [ this allows ->select_task() to simply return task_cpu(p) and
1650 * not worry about this generic constraint ]
1652 if (unlikely(!cpumask_test_cpu(cpu
, tsk_cpus_allowed(p
)) ||
1654 cpu
= select_fallback_rq(task_cpu(p
), p
);
1659 static void update_avg(u64
*avg
, u64 sample
)
1661 s64 diff
= sample
- *avg
;
1667 static inline int __set_cpus_allowed_ptr(struct task_struct
*p
,
1668 const struct cpumask
*new_mask
, bool check
)
1670 return set_cpus_allowed_ptr(p
, new_mask
);
1673 #endif /* CONFIG_SMP */
1676 ttwu_stat(struct task_struct
*p
, int cpu
, int wake_flags
)
1678 #ifdef CONFIG_SCHEDSTATS
1679 struct rq
*rq
= this_rq();
1682 int this_cpu
= smp_processor_id();
1684 if (cpu
== this_cpu
) {
1685 schedstat_inc(rq
, ttwu_local
);
1686 schedstat_inc(p
, se
.statistics
.nr_wakeups_local
);
1688 struct sched_domain
*sd
;
1690 schedstat_inc(p
, se
.statistics
.nr_wakeups_remote
);
1692 for_each_domain(this_cpu
, sd
) {
1693 if (cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
1694 schedstat_inc(sd
, ttwu_wake_remote
);
1701 if (wake_flags
& WF_MIGRATED
)
1702 schedstat_inc(p
, se
.statistics
.nr_wakeups_migrate
);
1704 #endif /* CONFIG_SMP */
1706 schedstat_inc(rq
, ttwu_count
);
1707 schedstat_inc(p
, se
.statistics
.nr_wakeups
);
1709 if (wake_flags
& WF_SYNC
)
1710 schedstat_inc(p
, se
.statistics
.nr_wakeups_sync
);
1712 #endif /* CONFIG_SCHEDSTATS */
1715 static inline void ttwu_activate(struct rq
*rq
, struct task_struct
*p
, int en_flags
)
1717 activate_task(rq
, p
, en_flags
);
1718 p
->on_rq
= TASK_ON_RQ_QUEUED
;
1720 /* if a worker is waking up, notify workqueue */
1721 if (p
->flags
& PF_WQ_WORKER
)
1722 wq_worker_waking_up(p
, cpu_of(rq
));
1726 * Mark the task runnable and perform wakeup-preemption.
1729 ttwu_do_wakeup(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1731 check_preempt_curr(rq
, p
, wake_flags
);
1732 p
->state
= TASK_RUNNING
;
1733 trace_sched_wakeup(p
);
1736 if (p
->sched_class
->task_woken
) {
1738 * Our task @p is fully woken up and running; so its safe to
1739 * drop the rq->lock, hereafter rq is only used for statistics.
1741 lockdep_unpin_lock(&rq
->lock
);
1742 p
->sched_class
->task_woken(rq
, p
);
1743 lockdep_pin_lock(&rq
->lock
);
1746 if (rq
->idle_stamp
) {
1747 u64 delta
= rq_clock(rq
) - rq
->idle_stamp
;
1748 u64 max
= 2*rq
->max_idle_balance_cost
;
1750 update_avg(&rq
->avg_idle
, delta
);
1752 if (rq
->avg_idle
> max
)
1761 ttwu_do_activate(struct rq
*rq
, struct task_struct
*p
, int wake_flags
)
1763 lockdep_assert_held(&rq
->lock
);
1766 if (p
->sched_contributes_to_load
)
1767 rq
->nr_uninterruptible
--;
1770 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
| ENQUEUE_WAKING
);
1771 ttwu_do_wakeup(rq
, p
, wake_flags
);
1775 * Called in case the task @p isn't fully descheduled from its runqueue,
1776 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1777 * since all we need to do is flip p->state to TASK_RUNNING, since
1778 * the task is still ->on_rq.
1780 static int ttwu_remote(struct task_struct
*p
, int wake_flags
)
1785 rq
= __task_rq_lock(p
);
1786 if (task_on_rq_queued(p
)) {
1787 /* check_preempt_curr() may use rq clock */
1788 update_rq_clock(rq
);
1789 ttwu_do_wakeup(rq
, p
, wake_flags
);
1792 __task_rq_unlock(rq
);
1798 void sched_ttwu_pending(void)
1800 struct rq
*rq
= this_rq();
1801 struct llist_node
*llist
= llist_del_all(&rq
->wake_list
);
1802 struct task_struct
*p
;
1803 unsigned long flags
;
1808 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1809 lockdep_pin_lock(&rq
->lock
);
1812 p
= llist_entry(llist
, struct task_struct
, wake_entry
);
1813 llist
= llist_next(llist
);
1814 ttwu_do_activate(rq
, p
, 0);
1817 lockdep_unpin_lock(&rq
->lock
);
1818 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1821 void scheduler_ipi(void)
1824 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
1825 * TIF_NEED_RESCHED remotely (for the first time) will also send
1828 preempt_fold_need_resched();
1830 if (llist_empty(&this_rq()->wake_list
) && !got_nohz_idle_kick())
1834 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1835 * traditionally all their work was done from the interrupt return
1836 * path. Now that we actually do some work, we need to make sure
1839 * Some archs already do call them, luckily irq_enter/exit nest
1842 * Arguably we should visit all archs and update all handlers,
1843 * however a fair share of IPIs are still resched only so this would
1844 * somewhat pessimize the simple resched case.
1847 sched_ttwu_pending();
1850 * Check if someone kicked us for doing the nohz idle load balance.
1852 if (unlikely(got_nohz_idle_kick())) {
1853 this_rq()->idle_balance
= 1;
1854 raise_softirq_irqoff(SCHED_SOFTIRQ
);
1859 static void ttwu_queue_remote(struct task_struct
*p
, int cpu
)
1861 struct rq
*rq
= cpu_rq(cpu
);
1863 if (llist_add(&p
->wake_entry
, &cpu_rq(cpu
)->wake_list
)) {
1864 if (!set_nr_if_polling(rq
->idle
))
1865 smp_send_reschedule(cpu
);
1867 trace_sched_wake_idle_without_ipi(cpu
);
1871 void wake_up_if_idle(int cpu
)
1873 struct rq
*rq
= cpu_rq(cpu
);
1874 unsigned long flags
;
1878 if (!is_idle_task(rcu_dereference(rq
->curr
)))
1881 if (set_nr_if_polling(rq
->idle
)) {
1882 trace_sched_wake_idle_without_ipi(cpu
);
1884 raw_spin_lock_irqsave(&rq
->lock
, flags
);
1885 if (is_idle_task(rq
->curr
))
1886 smp_send_reschedule(cpu
);
1887 /* Else cpu is not in idle, do nothing here */
1888 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
1895 bool cpus_share_cache(int this_cpu
, int that_cpu
)
1897 return per_cpu(sd_llc_id
, this_cpu
) == per_cpu(sd_llc_id
, that_cpu
);
1899 #endif /* CONFIG_SMP */
1901 static void ttwu_queue(struct task_struct
*p
, int cpu
)
1903 struct rq
*rq
= cpu_rq(cpu
);
1905 #if defined(CONFIG_SMP)
1906 if (sched_feat(TTWU_QUEUE
) && !cpus_share_cache(smp_processor_id(), cpu
)) {
1907 sched_clock_cpu(cpu
); /* sync clocks x-cpu */
1908 ttwu_queue_remote(p
, cpu
);
1913 raw_spin_lock(&rq
->lock
);
1914 lockdep_pin_lock(&rq
->lock
);
1915 ttwu_do_activate(rq
, p
, 0);
1916 lockdep_unpin_lock(&rq
->lock
);
1917 raw_spin_unlock(&rq
->lock
);
1921 * Notes on Program-Order guarantees on SMP systems.
1925 * The basic program-order guarantee on SMP systems is that when a task [t]
1926 * migrates, all its activity on its old cpu [c0] happens-before any subsequent
1927 * execution on its new cpu [c1].
1929 * For migration (of runnable tasks) this is provided by the following means:
1931 * A) UNLOCK of the rq(c0)->lock scheduling out task t
1932 * B) migration for t is required to synchronize *both* rq(c0)->lock and
1933 * rq(c1)->lock (if not at the same time, then in that order).
1934 * C) LOCK of the rq(c1)->lock scheduling in task
1936 * Transitivity guarantees that B happens after A and C after B.
1937 * Note: we only require RCpc transitivity.
1938 * Note: the cpu doing B need not be c0 or c1
1947 * UNLOCK rq(0)->lock
1949 * LOCK rq(0)->lock // orders against CPU0
1951 * UNLOCK rq(0)->lock
1955 * UNLOCK rq(1)->lock
1957 * LOCK rq(1)->lock // orders against CPU2
1960 * UNLOCK rq(1)->lock
1963 * BLOCKING -- aka. SLEEP + WAKEUP
1965 * For blocking we (obviously) need to provide the same guarantee as for
1966 * migration. However the means are completely different as there is no lock
1967 * chain to provide order. Instead we do:
1969 * 1) smp_store_release(X->on_cpu, 0)
1970 * 2) smp_cond_acquire(!X->on_cpu)
1974 * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule)
1976 * LOCK rq(0)->lock LOCK X->pi_lock
1979 * smp_store_release(X->on_cpu, 0);
1981 * smp_cond_acquire(!X->on_cpu);
1987 * X->state = RUNNING
1988 * UNLOCK rq(2)->lock
1990 * LOCK rq(2)->lock // orders against CPU1
1993 * UNLOCK rq(2)->lock
1996 * UNLOCK rq(0)->lock
1999 * However; for wakeups there is a second guarantee we must provide, namely we
2000 * must observe the state that lead to our wakeup. That is, not only must our
2001 * task observe its own prior state, it must also observe the stores prior to
2004 * This means that any means of doing remote wakeups must order the CPU doing
2005 * the wakeup against the CPU the task is going to end up running on. This,
2006 * however, is already required for the regular Program-Order guarantee above,
2007 * since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire).
2012 * try_to_wake_up - wake up a thread
2013 * @p: the thread to be awakened
2014 * @state: the mask of task states that can be woken
2015 * @wake_flags: wake modifier flags (WF_*)
2017 * Put it on the run-queue if it's not already there. The "current"
2018 * thread is always on the run-queue (except when the actual
2019 * re-schedule is in progress), and as such you're allowed to do
2020 * the simpler "current->state = TASK_RUNNING" to mark yourself
2021 * runnable without the overhead of this.
2023 * Return: %true if @p was woken up, %false if it was already running.
2024 * or @state didn't match @p's state.
2027 try_to_wake_up(struct task_struct
*p
, unsigned int state
, int wake_flags
)
2029 unsigned long flags
;
2030 int cpu
, success
= 0;
2033 * If we are going to wake up a thread waiting for CONDITION we
2034 * need to ensure that CONDITION=1 done by the caller can not be
2035 * reordered with p->state check below. This pairs with mb() in
2036 * set_current_state() the waiting thread does.
2038 smp_mb__before_spinlock();
2039 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2040 if (!(p
->state
& state
))
2043 trace_sched_waking(p
);
2045 success
= 1; /* we're going to change ->state */
2048 if (p
->on_rq
&& ttwu_remote(p
, wake_flags
))
2053 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
2054 * possible to, falsely, observe p->on_cpu == 0.
2056 * One must be running (->on_cpu == 1) in order to remove oneself
2057 * from the runqueue.
2059 * [S] ->on_cpu = 1; [L] ->on_rq
2063 * [S] ->on_rq = 0; [L] ->on_cpu
2065 * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
2066 * from the consecutive calls to schedule(); the first switching to our
2067 * task, the second putting it to sleep.
2072 * If the owning (remote) cpu is still in the middle of schedule() with
2073 * this task as prev, wait until its done referencing the task.
2075 * Pairs with the smp_store_release() in finish_lock_switch().
2077 * This ensures that tasks getting woken will be fully ordered against
2078 * their previous state and preserve Program Order.
2080 smp_cond_acquire(!p
->on_cpu
);
2082 p
->sched_contributes_to_load
= !!task_contributes_to_load(p
);
2083 p
->state
= TASK_WAKING
;
2085 if (p
->sched_class
->task_waking
)
2086 p
->sched_class
->task_waking(p
);
2088 cpu
= select_task_rq(p
, p
->wake_cpu
, SD_BALANCE_WAKE
, wake_flags
);
2089 if (task_cpu(p
) != cpu
) {
2090 wake_flags
|= WF_MIGRATED
;
2091 set_task_cpu(p
, cpu
);
2093 #endif /* CONFIG_SMP */
2097 ttwu_stat(p
, cpu
, wake_flags
);
2099 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2105 * try_to_wake_up_local - try to wake up a local task with rq lock held
2106 * @p: the thread to be awakened
2108 * Put @p on the run-queue if it's not already there. The caller must
2109 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2112 static void try_to_wake_up_local(struct task_struct
*p
)
2114 struct rq
*rq
= task_rq(p
);
2116 if (WARN_ON_ONCE(rq
!= this_rq()) ||
2117 WARN_ON_ONCE(p
== current
))
2120 lockdep_assert_held(&rq
->lock
);
2122 if (!raw_spin_trylock(&p
->pi_lock
)) {
2124 * This is OK, because current is on_cpu, which avoids it being
2125 * picked for load-balance and preemption/IRQs are still
2126 * disabled avoiding further scheduler activity on it and we've
2127 * not yet picked a replacement task.
2129 lockdep_unpin_lock(&rq
->lock
);
2130 raw_spin_unlock(&rq
->lock
);
2131 raw_spin_lock(&p
->pi_lock
);
2132 raw_spin_lock(&rq
->lock
);
2133 lockdep_pin_lock(&rq
->lock
);
2136 if (!(p
->state
& TASK_NORMAL
))
2139 trace_sched_waking(p
);
2141 if (!task_on_rq_queued(p
))
2142 ttwu_activate(rq
, p
, ENQUEUE_WAKEUP
);
2144 ttwu_do_wakeup(rq
, p
, 0);
2145 ttwu_stat(p
, smp_processor_id(), 0);
2147 raw_spin_unlock(&p
->pi_lock
);
2151 * wake_up_process - Wake up a specific process
2152 * @p: The process to be woken up.
2154 * Attempt to wake up the nominated process and move it to the set of runnable
2157 * Return: 1 if the process was woken up, 0 if it was already running.
2159 * It may be assumed that this function implies a write memory barrier before
2160 * changing the task state if and only if any tasks are woken up.
2162 int wake_up_process(struct task_struct
*p
)
2164 return try_to_wake_up(p
, TASK_NORMAL
, 0);
2166 EXPORT_SYMBOL(wake_up_process
);
2168 int wake_up_state(struct task_struct
*p
, unsigned int state
)
2170 return try_to_wake_up(p
, state
, 0);
2174 * This function clears the sched_dl_entity static params.
2176 void __dl_clear_params(struct task_struct
*p
)
2178 struct sched_dl_entity
*dl_se
= &p
->dl
;
2180 dl_se
->dl_runtime
= 0;
2181 dl_se
->dl_deadline
= 0;
2182 dl_se
->dl_period
= 0;
2186 dl_se
->dl_throttled
= 0;
2188 dl_se
->dl_yielded
= 0;
2192 * Perform scheduler related setup for a newly forked process p.
2193 * p is forked by current.
2195 * __sched_fork() is basic setup used by init_idle() too:
2197 static void __sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
2202 p
->se
.exec_start
= 0;
2203 p
->se
.sum_exec_runtime
= 0;
2204 p
->se
.prev_sum_exec_runtime
= 0;
2205 p
->se
.nr_migrations
= 0;
2207 INIT_LIST_HEAD(&p
->se
.group_node
);
2209 #ifdef CONFIG_FAIR_GROUP_SCHED
2210 p
->se
.cfs_rq
= NULL
;
2213 #ifdef CONFIG_SCHEDSTATS
2214 memset(&p
->se
.statistics
, 0, sizeof(p
->se
.statistics
));
2217 RB_CLEAR_NODE(&p
->dl
.rb_node
);
2218 init_dl_task_timer(&p
->dl
);
2219 __dl_clear_params(p
);
2221 INIT_LIST_HEAD(&p
->rt
.run_list
);
2223 #ifdef CONFIG_PREEMPT_NOTIFIERS
2224 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
2227 #ifdef CONFIG_NUMA_BALANCING
2228 if (p
->mm
&& atomic_read(&p
->mm
->mm_users
) == 1) {
2229 p
->mm
->numa_next_scan
= jiffies
+ msecs_to_jiffies(sysctl_numa_balancing_scan_delay
);
2230 p
->mm
->numa_scan_seq
= 0;
2233 if (clone_flags
& CLONE_VM
)
2234 p
->numa_preferred_nid
= current
->numa_preferred_nid
;
2236 p
->numa_preferred_nid
= -1;
2238 p
->node_stamp
= 0ULL;
2239 p
->numa_scan_seq
= p
->mm
? p
->mm
->numa_scan_seq
: 0;
2240 p
->numa_scan_period
= sysctl_numa_balancing_scan_delay
;
2241 p
->numa_work
.next
= &p
->numa_work
;
2242 p
->numa_faults
= NULL
;
2243 p
->last_task_numa_placement
= 0;
2244 p
->last_sum_exec_runtime
= 0;
2246 p
->numa_group
= NULL
;
2247 #endif /* CONFIG_NUMA_BALANCING */
2250 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing
);
2252 #ifdef CONFIG_NUMA_BALANCING
2254 void set_numabalancing_state(bool enabled
)
2257 static_branch_enable(&sched_numa_balancing
);
2259 static_branch_disable(&sched_numa_balancing
);
2262 #ifdef CONFIG_PROC_SYSCTL
2263 int sysctl_numa_balancing(struct ctl_table
*table
, int write
,
2264 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2268 int state
= static_branch_likely(&sched_numa_balancing
);
2270 if (write
&& !capable(CAP_SYS_ADMIN
))
2275 err
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2279 set_numabalancing_state(state
);
2286 * fork()/clone()-time setup:
2288 int sched_fork(unsigned long clone_flags
, struct task_struct
*p
)
2290 unsigned long flags
;
2291 int cpu
= get_cpu();
2293 __sched_fork(clone_flags
, p
);
2295 * We mark the process as running here. This guarantees that
2296 * nobody will actually run it, and a signal or other external
2297 * event cannot wake it up and insert it on the runqueue either.
2299 p
->state
= TASK_RUNNING
;
2302 * Make sure we do not leak PI boosting priority to the child.
2304 p
->prio
= current
->normal_prio
;
2307 * Revert to default priority/policy on fork if requested.
2309 if (unlikely(p
->sched_reset_on_fork
)) {
2310 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
2311 p
->policy
= SCHED_NORMAL
;
2312 p
->static_prio
= NICE_TO_PRIO(0);
2314 } else if (PRIO_TO_NICE(p
->static_prio
) < 0)
2315 p
->static_prio
= NICE_TO_PRIO(0);
2317 p
->prio
= p
->normal_prio
= __normal_prio(p
);
2321 * We don't need the reset flag anymore after the fork. It has
2322 * fulfilled its duty:
2324 p
->sched_reset_on_fork
= 0;
2327 if (dl_prio(p
->prio
)) {
2330 } else if (rt_prio(p
->prio
)) {
2331 p
->sched_class
= &rt_sched_class
;
2333 p
->sched_class
= &fair_sched_class
;
2336 if (p
->sched_class
->task_fork
)
2337 p
->sched_class
->task_fork(p
);
2340 * The child is not yet in the pid-hash so no cgroup attach races,
2341 * and the cgroup is pinned to this child due to cgroup_fork()
2342 * is ran before sched_fork().
2344 * Silence PROVE_RCU.
2346 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2347 set_task_cpu(p
, cpu
);
2348 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2350 #ifdef CONFIG_SCHED_INFO
2351 if (likely(sched_info_on()))
2352 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
2354 #if defined(CONFIG_SMP)
2357 init_task_preempt_count(p
);
2359 plist_node_init(&p
->pushable_tasks
, MAX_PRIO
);
2360 RB_CLEAR_NODE(&p
->pushable_dl_tasks
);
2367 unsigned long to_ratio(u64 period
, u64 runtime
)
2369 if (runtime
== RUNTIME_INF
)
2373 * Doing this here saves a lot of checks in all
2374 * the calling paths, and returning zero seems
2375 * safe for them anyway.
2380 return div64_u64(runtime
<< 20, period
);
2384 inline struct dl_bw
*dl_bw_of(int i
)
2386 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2387 "sched RCU must be held");
2388 return &cpu_rq(i
)->rd
->dl_bw
;
2391 static inline int dl_bw_cpus(int i
)
2393 struct root_domain
*rd
= cpu_rq(i
)->rd
;
2396 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
2397 "sched RCU must be held");
2398 for_each_cpu_and(i
, rd
->span
, cpu_active_mask
)
2404 inline struct dl_bw
*dl_bw_of(int i
)
2406 return &cpu_rq(i
)->dl
.dl_bw
;
2409 static inline int dl_bw_cpus(int i
)
2416 * We must be sure that accepting a new task (or allowing changing the
2417 * parameters of an existing one) is consistent with the bandwidth
2418 * constraints. If yes, this function also accordingly updates the currently
2419 * allocated bandwidth to reflect the new situation.
2421 * This function is called while holding p's rq->lock.
2423 * XXX we should delay bw change until the task's 0-lag point, see
2426 static int dl_overflow(struct task_struct
*p
, int policy
,
2427 const struct sched_attr
*attr
)
2430 struct dl_bw
*dl_b
= dl_bw_of(task_cpu(p
));
2431 u64 period
= attr
->sched_period
?: attr
->sched_deadline
;
2432 u64 runtime
= attr
->sched_runtime
;
2433 u64 new_bw
= dl_policy(policy
) ? to_ratio(period
, runtime
) : 0;
2436 if (new_bw
== p
->dl
.dl_bw
)
2440 * Either if a task, enters, leave, or stays -deadline but changes
2441 * its parameters, we may need to update accordingly the total
2442 * allocated bandwidth of the container.
2444 raw_spin_lock(&dl_b
->lock
);
2445 cpus
= dl_bw_cpus(task_cpu(p
));
2446 if (dl_policy(policy
) && !task_has_dl_policy(p
) &&
2447 !__dl_overflow(dl_b
, cpus
, 0, new_bw
)) {
2448 __dl_add(dl_b
, new_bw
);
2450 } else if (dl_policy(policy
) && task_has_dl_policy(p
) &&
2451 !__dl_overflow(dl_b
, cpus
, p
->dl
.dl_bw
, new_bw
)) {
2452 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2453 __dl_add(dl_b
, new_bw
);
2455 } else if (!dl_policy(policy
) && task_has_dl_policy(p
)) {
2456 __dl_clear(dl_b
, p
->dl
.dl_bw
);
2459 raw_spin_unlock(&dl_b
->lock
);
2464 extern void init_dl_bw(struct dl_bw
*dl_b
);
2467 * wake_up_new_task - wake up a newly created task for the first time.
2469 * This function will do some initial scheduler statistics housekeeping
2470 * that must be done for every newly created context, then puts the task
2471 * on the runqueue and wakes it.
2473 void wake_up_new_task(struct task_struct
*p
)
2475 unsigned long flags
;
2478 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2479 /* Initialize new task's runnable average */
2480 init_entity_runnable_average(&p
->se
);
2483 * Fork balancing, do it here and not earlier because:
2484 * - cpus_allowed can change in the fork path
2485 * - any previously selected cpu might disappear through hotplug
2487 set_task_cpu(p
, select_task_rq(p
, task_cpu(p
), SD_BALANCE_FORK
, 0));
2490 rq
= __task_rq_lock(p
);
2491 activate_task(rq
, p
, 0);
2492 p
->on_rq
= TASK_ON_RQ_QUEUED
;
2493 trace_sched_wakeup_new(p
);
2494 check_preempt_curr(rq
, p
, WF_FORK
);
2496 if (p
->sched_class
->task_woken
) {
2498 * Nothing relies on rq->lock after this, so its fine to
2501 lockdep_unpin_lock(&rq
->lock
);
2502 p
->sched_class
->task_woken(rq
, p
);
2503 lockdep_pin_lock(&rq
->lock
);
2506 task_rq_unlock(rq
, p
, &flags
);
2509 #ifdef CONFIG_PREEMPT_NOTIFIERS
2511 static struct static_key preempt_notifier_key
= STATIC_KEY_INIT_FALSE
;
2513 void preempt_notifier_inc(void)
2515 static_key_slow_inc(&preempt_notifier_key
);
2517 EXPORT_SYMBOL_GPL(preempt_notifier_inc
);
2519 void preempt_notifier_dec(void)
2521 static_key_slow_dec(&preempt_notifier_key
);
2523 EXPORT_SYMBOL_GPL(preempt_notifier_dec
);
2526 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2527 * @notifier: notifier struct to register
2529 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2531 if (!static_key_false(&preempt_notifier_key
))
2532 WARN(1, "registering preempt_notifier while notifiers disabled\n");
2534 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2536 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2539 * preempt_notifier_unregister - no longer interested in preemption notifications
2540 * @notifier: notifier struct to unregister
2542 * This is *not* safe to call from within a preemption notifier.
2544 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2546 hlist_del(¬ifier
->link
);
2548 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2550 static void __fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2552 struct preempt_notifier
*notifier
;
2554 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2555 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2558 static __always_inline
void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2560 if (static_key_false(&preempt_notifier_key
))
2561 __fire_sched_in_preempt_notifiers(curr
);
2565 __fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2566 struct task_struct
*next
)
2568 struct preempt_notifier
*notifier
;
2570 hlist_for_each_entry(notifier
, &curr
->preempt_notifiers
, link
)
2571 notifier
->ops
->sched_out(notifier
, next
);
2574 static __always_inline
void
2575 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2576 struct task_struct
*next
)
2578 if (static_key_false(&preempt_notifier_key
))
2579 __fire_sched_out_preempt_notifiers(curr
, next
);
2582 #else /* !CONFIG_PREEMPT_NOTIFIERS */
2584 static inline void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2589 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2590 struct task_struct
*next
)
2594 #endif /* CONFIG_PREEMPT_NOTIFIERS */
2597 * prepare_task_switch - prepare to switch tasks
2598 * @rq: the runqueue preparing to switch
2599 * @prev: the current task that is being switched out
2600 * @next: the task we are going to switch to.
2602 * This is called with the rq lock held and interrupts off. It must
2603 * be paired with a subsequent finish_task_switch after the context
2606 * prepare_task_switch sets up locking and calls architecture specific
2610 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
2611 struct task_struct
*next
)
2613 sched_info_switch(rq
, prev
, next
);
2614 perf_event_task_sched_out(prev
, next
);
2615 fire_sched_out_preempt_notifiers(prev
, next
);
2616 prepare_lock_switch(rq
, next
);
2617 prepare_arch_switch(next
);
2621 * finish_task_switch - clean up after a task-switch
2622 * @prev: the thread we just switched away from.
2624 * finish_task_switch must be called after the context switch, paired
2625 * with a prepare_task_switch call before the context switch.
2626 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2627 * and do any other architecture-specific cleanup actions.
2629 * Note that we may have delayed dropping an mm in context_switch(). If
2630 * so, we finish that here outside of the runqueue lock. (Doing it
2631 * with the lock held can cause deadlocks; see schedule() for
2634 * The context switch have flipped the stack from under us and restored the
2635 * local variables which were saved when this task called schedule() in the
2636 * past. prev == current is still correct but we need to recalculate this_rq
2637 * because prev may have moved to another CPU.
2639 static struct rq
*finish_task_switch(struct task_struct
*prev
)
2640 __releases(rq
->lock
)
2642 struct rq
*rq
= this_rq();
2643 struct mm_struct
*mm
= rq
->prev_mm
;
2647 * The previous task will have left us with a preempt_count of 2
2648 * because it left us after:
2651 * preempt_disable(); // 1
2653 * raw_spin_lock_irq(&rq->lock) // 2
2655 * Also, see FORK_PREEMPT_COUNT.
2657 if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET
,
2658 "corrupted preempt_count: %s/%d/0x%x\n",
2659 current
->comm
, current
->pid
, preempt_count()))
2660 preempt_count_set(FORK_PREEMPT_COUNT
);
2665 * A task struct has one reference for the use as "current".
2666 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2667 * schedule one last time. The schedule call will never return, and
2668 * the scheduled task must drop that reference.
2670 * We must observe prev->state before clearing prev->on_cpu (in
2671 * finish_lock_switch), otherwise a concurrent wakeup can get prev
2672 * running on another CPU and we could rave with its RUNNING -> DEAD
2673 * transition, resulting in a double drop.
2675 prev_state
= prev
->state
;
2676 vtime_task_switch(prev
);
2677 perf_event_task_sched_in(prev
, current
);
2678 finish_lock_switch(rq
, prev
);
2679 finish_arch_post_lock_switch();
2681 fire_sched_in_preempt_notifiers(current
);
2684 if (unlikely(prev_state
== TASK_DEAD
)) {
2685 if (prev
->sched_class
->task_dead
)
2686 prev
->sched_class
->task_dead(prev
);
2689 * Remove function-return probe instances associated with this
2690 * task and put them back on the free list.
2692 kprobe_flush_task(prev
);
2693 put_task_struct(prev
);
2696 tick_nohz_task_switch();
2702 /* rq->lock is NOT held, but preemption is disabled */
2703 static void __balance_callback(struct rq
*rq
)
2705 struct callback_head
*head
, *next
;
2706 void (*func
)(struct rq
*rq
);
2707 unsigned long flags
;
2709 raw_spin_lock_irqsave(&rq
->lock
, flags
);
2710 head
= rq
->balance_callback
;
2711 rq
->balance_callback
= NULL
;
2713 func
= (void (*)(struct rq
*))head
->func
;
2720 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
2723 static inline void balance_callback(struct rq
*rq
)
2725 if (unlikely(rq
->balance_callback
))
2726 __balance_callback(rq
);
2731 static inline void balance_callback(struct rq
*rq
)
2738 * schedule_tail - first thing a freshly forked thread must call.
2739 * @prev: the thread we just switched away from.
2741 asmlinkage __visible
void schedule_tail(struct task_struct
*prev
)
2742 __releases(rq
->lock
)
2747 * New tasks start with FORK_PREEMPT_COUNT, see there and
2748 * finish_task_switch() for details.
2750 * finish_task_switch() will drop rq->lock() and lower preempt_count
2751 * and the preempt_enable() will end up enabling preemption (on
2752 * PREEMPT_COUNT kernels).
2755 rq
= finish_task_switch(prev
);
2756 balance_callback(rq
);
2759 if (current
->set_child_tid
)
2760 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2764 * context_switch - switch to the new MM and the new thread's register state.
2766 static inline struct rq
*
2767 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2768 struct task_struct
*next
)
2770 struct mm_struct
*mm
, *oldmm
;
2772 prepare_task_switch(rq
, prev
, next
);
2775 oldmm
= prev
->active_mm
;
2777 * For paravirt, this is coupled with an exit in switch_to to
2778 * combine the page table reload and the switch backend into
2781 arch_start_context_switch(prev
);
2784 next
->active_mm
= oldmm
;
2785 atomic_inc(&oldmm
->mm_count
);
2786 enter_lazy_tlb(oldmm
, next
);
2788 switch_mm(oldmm
, mm
, next
);
2791 prev
->active_mm
= NULL
;
2792 rq
->prev_mm
= oldmm
;
2795 * Since the runqueue lock will be released by the next
2796 * task (which is an invalid locking op but in the case
2797 * of the scheduler it's an obvious special-case), so we
2798 * do an early lockdep release here:
2800 lockdep_unpin_lock(&rq
->lock
);
2801 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2803 /* Here we just switch the register state and the stack. */
2804 switch_to(prev
, next
, prev
);
2807 return finish_task_switch(prev
);
2811 * nr_running and nr_context_switches:
2813 * externally visible scheduler statistics: current number of runnable
2814 * threads, total number of context switches performed since bootup.
2816 unsigned long nr_running(void)
2818 unsigned long i
, sum
= 0;
2820 for_each_online_cpu(i
)
2821 sum
+= cpu_rq(i
)->nr_running
;
2827 * Check if only the current task is running on the cpu.
2829 * Caution: this function does not check that the caller has disabled
2830 * preemption, thus the result might have a time-of-check-to-time-of-use
2831 * race. The caller is responsible to use it correctly, for example:
2833 * - from a non-preemptable section (of course)
2835 * - from a thread that is bound to a single CPU
2837 * - in a loop with very short iterations (e.g. a polling loop)
2839 bool single_task_running(void)
2841 return raw_rq()->nr_running
== 1;
2843 EXPORT_SYMBOL(single_task_running
);
2845 unsigned long long nr_context_switches(void)
2848 unsigned long long sum
= 0;
2850 for_each_possible_cpu(i
)
2851 sum
+= cpu_rq(i
)->nr_switches
;
2856 unsigned long nr_iowait(void)
2858 unsigned long i
, sum
= 0;
2860 for_each_possible_cpu(i
)
2861 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2866 unsigned long nr_iowait_cpu(int cpu
)
2868 struct rq
*this = cpu_rq(cpu
);
2869 return atomic_read(&this->nr_iowait
);
2872 void get_iowait_load(unsigned long *nr_waiters
, unsigned long *load
)
2874 struct rq
*rq
= this_rq();
2875 *nr_waiters
= atomic_read(&rq
->nr_iowait
);
2876 *load
= rq
->load
.weight
;
2882 * sched_exec - execve() is a valuable balancing opportunity, because at
2883 * this point the task has the smallest effective memory and cache footprint.
2885 void sched_exec(void)
2887 struct task_struct
*p
= current
;
2888 unsigned long flags
;
2891 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
2892 dest_cpu
= p
->sched_class
->select_task_rq(p
, task_cpu(p
), SD_BALANCE_EXEC
, 0);
2893 if (dest_cpu
== smp_processor_id())
2896 if (likely(cpu_active(dest_cpu
))) {
2897 struct migration_arg arg
= { p
, dest_cpu
};
2899 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2900 stop_one_cpu(task_cpu(p
), migration_cpu_stop
, &arg
);
2904 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
2909 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2910 DEFINE_PER_CPU(struct kernel_cpustat
, kernel_cpustat
);
2912 EXPORT_PER_CPU_SYMBOL(kstat
);
2913 EXPORT_PER_CPU_SYMBOL(kernel_cpustat
);
2916 * Return accounted runtime for the task.
2917 * In case the task is currently running, return the runtime plus current's
2918 * pending runtime that have not been accounted yet.
2920 unsigned long long task_sched_runtime(struct task_struct
*p
)
2922 unsigned long flags
;
2926 #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
2928 * 64-bit doesn't need locks to atomically read a 64bit value.
2929 * So we have a optimization chance when the task's delta_exec is 0.
2930 * Reading ->on_cpu is racy, but this is ok.
2932 * If we race with it leaving cpu, we'll take a lock. So we're correct.
2933 * If we race with it entering cpu, unaccounted time is 0. This is
2934 * indistinguishable from the read occurring a few cycles earlier.
2935 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
2936 * been accounted, so we're correct here as well.
2938 if (!p
->on_cpu
|| !task_on_rq_queued(p
))
2939 return p
->se
.sum_exec_runtime
;
2942 rq
= task_rq_lock(p
, &flags
);
2944 * Must be ->curr _and_ ->on_rq. If dequeued, we would
2945 * project cycles that may never be accounted to this
2946 * thread, breaking clock_gettime().
2948 if (task_current(rq
, p
) && task_on_rq_queued(p
)) {
2949 update_rq_clock(rq
);
2950 p
->sched_class
->update_curr(rq
);
2952 ns
= p
->se
.sum_exec_runtime
;
2953 task_rq_unlock(rq
, p
, &flags
);
2959 * This function gets called by the timer code, with HZ frequency.
2960 * We call it with interrupts disabled.
2962 void scheduler_tick(void)
2964 int cpu
= smp_processor_id();
2965 struct rq
*rq
= cpu_rq(cpu
);
2966 struct task_struct
*curr
= rq
->curr
;
2970 raw_spin_lock(&rq
->lock
);
2971 update_rq_clock(rq
);
2972 curr
->sched_class
->task_tick(rq
, curr
, 0);
2973 update_cpu_load_active(rq
);
2974 calc_global_load_tick(rq
);
2975 raw_spin_unlock(&rq
->lock
);
2977 perf_event_task_tick();
2980 rq
->idle_balance
= idle_cpu(cpu
);
2981 trigger_load_balance(rq
);
2983 rq_last_tick_reset(rq
);
2986 #ifdef CONFIG_NO_HZ_FULL
2988 * scheduler_tick_max_deferment
2990 * Keep at least one tick per second when a single
2991 * active task is running because the scheduler doesn't
2992 * yet completely support full dynticks environment.
2994 * This makes sure that uptime, CFS vruntime, load
2995 * balancing, etc... continue to move forward, even
2996 * with a very low granularity.
2998 * Return: Maximum deferment in nanoseconds.
3000 u64
scheduler_tick_max_deferment(void)
3002 struct rq
*rq
= this_rq();
3003 unsigned long next
, now
= READ_ONCE(jiffies
);
3005 next
= rq
->last_sched_tick
+ HZ
;
3007 if (time_before_eq(next
, now
))
3010 return jiffies_to_nsecs(next
- now
);
3014 notrace
unsigned long get_parent_ip(unsigned long addr
)
3016 if (in_lock_functions(addr
)) {
3017 addr
= CALLER_ADDR2
;
3018 if (in_lock_functions(addr
))
3019 addr
= CALLER_ADDR3
;
3024 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
3025 defined(CONFIG_PREEMPT_TRACER))
3027 void preempt_count_add(int val
)
3029 #ifdef CONFIG_DEBUG_PREEMPT
3033 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3036 __preempt_count_add(val
);
3037 #ifdef CONFIG_DEBUG_PREEMPT
3039 * Spinlock count overflowing soon?
3041 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3044 if (preempt_count() == val
) {
3045 unsigned long ip
= get_parent_ip(CALLER_ADDR1
);
3046 #ifdef CONFIG_DEBUG_PREEMPT
3047 current
->preempt_disable_ip
= ip
;
3049 trace_preempt_off(CALLER_ADDR0
, ip
);
3052 EXPORT_SYMBOL(preempt_count_add
);
3053 NOKPROBE_SYMBOL(preempt_count_add
);
3055 void preempt_count_sub(int val
)
3057 #ifdef CONFIG_DEBUG_PREEMPT
3061 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3064 * Is the spinlock portion underflowing?
3066 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3067 !(preempt_count() & PREEMPT_MASK
)))
3071 if (preempt_count() == val
)
3072 trace_preempt_on(CALLER_ADDR0
, get_parent_ip(CALLER_ADDR1
));
3073 __preempt_count_sub(val
);
3075 EXPORT_SYMBOL(preempt_count_sub
);
3076 NOKPROBE_SYMBOL(preempt_count_sub
);
3081 * Print scheduling while atomic bug:
3083 static noinline
void __schedule_bug(struct task_struct
*prev
)
3085 if (oops_in_progress
)
3088 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3089 prev
->comm
, prev
->pid
, preempt_count());
3091 debug_show_held_locks(prev
);
3093 if (irqs_disabled())
3094 print_irqtrace_events(prev
);
3095 #ifdef CONFIG_DEBUG_PREEMPT
3096 if (in_atomic_preempt_off()) {
3097 pr_err("Preemption disabled at:");
3098 print_ip_sym(current
->preempt_disable_ip
);
3103 add_taint(TAINT_WARN
, LOCKDEP_STILL_OK
);
3107 * Various schedule()-time debugging checks and statistics:
3109 static inline void schedule_debug(struct task_struct
*prev
)
3111 #ifdef CONFIG_SCHED_STACK_END_CHECK
3112 BUG_ON(task_stack_end_corrupted(prev
));
3115 if (unlikely(in_atomic_preempt_off())) {
3116 __schedule_bug(prev
);
3117 preempt_count_set(PREEMPT_DISABLED
);
3121 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3123 schedstat_inc(this_rq(), sched_count
);
3127 * Pick up the highest-prio task:
3129 static inline struct task_struct
*
3130 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3132 const struct sched_class
*class = &fair_sched_class
;
3133 struct task_struct
*p
;
3136 * Optimization: we know that if all tasks are in
3137 * the fair class we can call that function directly:
3139 if (likely(prev
->sched_class
== class &&
3140 rq
->nr_running
== rq
->cfs
.h_nr_running
)) {
3141 p
= fair_sched_class
.pick_next_task(rq
, prev
);
3142 if (unlikely(p
== RETRY_TASK
))
3145 /* assumes fair_sched_class->next == idle_sched_class */
3147 p
= idle_sched_class
.pick_next_task(rq
, prev
);
3153 for_each_class(class) {
3154 p
= class->pick_next_task(rq
, prev
);
3156 if (unlikely(p
== RETRY_TASK
))
3162 BUG(); /* the idle class will always have a runnable task */
3166 * __schedule() is the main scheduler function.
3168 * The main means of driving the scheduler and thus entering this function are:
3170 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc.
3172 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
3173 * paths. For example, see arch/x86/entry_64.S.
3175 * To drive preemption between tasks, the scheduler sets the flag in timer
3176 * interrupt handler scheduler_tick().
3178 * 3. Wakeups don't really cause entry into schedule(). They add a
3179 * task to the run-queue and that's it.
3181 * Now, if the new task added to the run-queue preempts the current
3182 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
3183 * called on the nearest possible occasion:
3185 * - If the kernel is preemptible (CONFIG_PREEMPT=y):
3187 * - in syscall or exception context, at the next outmost
3188 * preempt_enable(). (this might be as soon as the wake_up()'s
3191 * - in IRQ context, return from interrupt-handler to
3192 * preemptible context
3194 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
3197 * - cond_resched() call
3198 * - explicit schedule() call
3199 * - return from syscall or exception to user-space
3200 * - return from interrupt-handler to user-space
3202 * WARNING: must be called with preemption disabled!
3204 static void __sched notrace
__schedule(bool preempt
)
3206 struct task_struct
*prev
, *next
;
3207 unsigned long *switch_count
;
3211 cpu
= smp_processor_id();
3216 * do_exit() calls schedule() with preemption disabled as an exception;
3217 * however we must fix that up, otherwise the next task will see an
3218 * inconsistent (higher) preempt count.
3220 * It also avoids the below schedule_debug() test from complaining
3223 if (unlikely(prev
->state
== TASK_DEAD
))
3224 preempt_enable_no_resched_notrace();
3226 schedule_debug(prev
);
3228 if (sched_feat(HRTICK
))
3231 local_irq_disable();
3232 rcu_note_context_switch();
3235 * Make sure that signal_pending_state()->signal_pending() below
3236 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
3237 * done by the caller to avoid the race with signal_wake_up().
3239 smp_mb__before_spinlock();
3240 raw_spin_lock(&rq
->lock
);
3241 lockdep_pin_lock(&rq
->lock
);
3243 rq
->clock_skip_update
<<= 1; /* promote REQ to ACT */
3245 switch_count
= &prev
->nivcsw
;
3246 if (!preempt
&& prev
->state
) {
3247 if (unlikely(signal_pending_state(prev
->state
, prev
))) {
3248 prev
->state
= TASK_RUNNING
;
3250 deactivate_task(rq
, prev
, DEQUEUE_SLEEP
);
3254 * If a worker went to sleep, notify and ask workqueue
3255 * whether it wants to wake up a task to maintain
3258 if (prev
->flags
& PF_WQ_WORKER
) {
3259 struct task_struct
*to_wakeup
;
3261 to_wakeup
= wq_worker_sleeping(prev
, cpu
);
3263 try_to_wake_up_local(to_wakeup
);
3266 switch_count
= &prev
->nvcsw
;
3269 if (task_on_rq_queued(prev
))
3270 update_rq_clock(rq
);
3272 next
= pick_next_task(rq
, prev
);
3273 clear_tsk_need_resched(prev
);
3274 clear_preempt_need_resched();
3275 rq
->clock_skip_update
= 0;
3277 if (likely(prev
!= next
)) {
3282 trace_sched_switch(preempt
, prev
, next
);
3283 rq
= context_switch(rq
, prev
, next
); /* unlocks the rq */
3286 lockdep_unpin_lock(&rq
->lock
);
3287 raw_spin_unlock_irq(&rq
->lock
);
3290 balance_callback(rq
);
3293 static inline void sched_submit_work(struct task_struct
*tsk
)
3295 if (!tsk
->state
|| tsk_is_pi_blocked(tsk
))
3298 * If we are going to sleep and we have plugged IO queued,
3299 * make sure to submit it to avoid deadlocks.
3301 if (blk_needs_flush_plug(tsk
))
3302 blk_schedule_flush_plug(tsk
);
3305 asmlinkage __visible
void __sched
schedule(void)
3307 struct task_struct
*tsk
= current
;
3309 sched_submit_work(tsk
);
3313 sched_preempt_enable_no_resched();
3314 } while (need_resched());
3316 EXPORT_SYMBOL(schedule
);
3318 #ifdef CONFIG_CONTEXT_TRACKING
3319 asmlinkage __visible
void __sched
schedule_user(void)
3322 * If we come here after a random call to set_need_resched(),
3323 * or we have been woken up remotely but the IPI has not yet arrived,
3324 * we haven't yet exited the RCU idle mode. Do it here manually until
3325 * we find a better solution.
3327 * NB: There are buggy callers of this function. Ideally we
3328 * should warn if prev_state != CONTEXT_USER, but that will trigger
3329 * too frequently to make sense yet.
3331 enum ctx_state prev_state
= exception_enter();
3333 exception_exit(prev_state
);
3338 * schedule_preempt_disabled - called with preemption disabled
3340 * Returns with preemption disabled. Note: preempt_count must be 1
3342 void __sched
schedule_preempt_disabled(void)
3344 sched_preempt_enable_no_resched();
3349 static void __sched notrace
preempt_schedule_common(void)
3352 preempt_disable_notrace();
3354 preempt_enable_no_resched_notrace();
3357 * Check again in case we missed a preemption opportunity
3358 * between schedule and now.
3360 } while (need_resched());
3363 #ifdef CONFIG_PREEMPT
3365 * this is the entry point to schedule() from in-kernel preemption
3366 * off of preempt_enable. Kernel preemptions off return from interrupt
3367 * occur there and call schedule directly.
3369 asmlinkage __visible
void __sched notrace
preempt_schedule(void)
3372 * If there is a non-zero preempt_count or interrupts are disabled,
3373 * we do not want to preempt the current task. Just return..
3375 if (likely(!preemptible()))
3378 preempt_schedule_common();
3380 NOKPROBE_SYMBOL(preempt_schedule
);
3381 EXPORT_SYMBOL(preempt_schedule
);
3384 * preempt_schedule_notrace - preempt_schedule called by tracing
3386 * The tracing infrastructure uses preempt_enable_notrace to prevent
3387 * recursion and tracing preempt enabling caused by the tracing
3388 * infrastructure itself. But as tracing can happen in areas coming
3389 * from userspace or just about to enter userspace, a preempt enable
3390 * can occur before user_exit() is called. This will cause the scheduler
3391 * to be called when the system is still in usermode.
3393 * To prevent this, the preempt_enable_notrace will use this function
3394 * instead of preempt_schedule() to exit user context if needed before
3395 * calling the scheduler.
3397 asmlinkage __visible
void __sched notrace
preempt_schedule_notrace(void)
3399 enum ctx_state prev_ctx
;
3401 if (likely(!preemptible()))
3405 preempt_disable_notrace();
3407 * Needs preempt disabled in case user_exit() is traced
3408 * and the tracer calls preempt_enable_notrace() causing
3409 * an infinite recursion.
3411 prev_ctx
= exception_enter();
3413 exception_exit(prev_ctx
);
3415 preempt_enable_no_resched_notrace();
3416 } while (need_resched());
3418 EXPORT_SYMBOL_GPL(preempt_schedule_notrace
);
3420 #endif /* CONFIG_PREEMPT */
3423 * this is the entry point to schedule() from kernel preemption
3424 * off of irq context.
3425 * Note, that this is called and return with irqs disabled. This will
3426 * protect us against recursive calling from irq.
3428 asmlinkage __visible
void __sched
preempt_schedule_irq(void)
3430 enum ctx_state prev_state
;
3432 /* Catch callers which need to be fixed */
3433 BUG_ON(preempt_count() || !irqs_disabled());
3435 prev_state
= exception_enter();
3441 local_irq_disable();
3442 sched_preempt_enable_no_resched();
3443 } while (need_resched());
3445 exception_exit(prev_state
);
3448 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int wake_flags
,
3451 return try_to_wake_up(curr
->private, mode
, wake_flags
);
3453 EXPORT_SYMBOL(default_wake_function
);
3455 #ifdef CONFIG_RT_MUTEXES
3458 * rt_mutex_setprio - set the current priority of a task
3460 * @prio: prio value (kernel-internal form)
3462 * This function changes the 'effective' priority of a task. It does
3463 * not touch ->normal_prio like __setscheduler().
3465 * Used by the rt_mutex code to implement priority inheritance
3466 * logic. Call site only calls if the priority of the task changed.
3468 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3470 int oldprio
, queued
, running
, enqueue_flag
= ENQUEUE_RESTORE
;
3472 const struct sched_class
*prev_class
;
3474 BUG_ON(prio
> MAX_PRIO
);
3476 rq
= __task_rq_lock(p
);
3479 * Idle task boosting is a nono in general. There is one
3480 * exception, when PREEMPT_RT and NOHZ is active:
3482 * The idle task calls get_next_timer_interrupt() and holds
3483 * the timer wheel base->lock on the CPU and another CPU wants
3484 * to access the timer (probably to cancel it). We can safely
3485 * ignore the boosting request, as the idle CPU runs this code
3486 * with interrupts disabled and will complete the lock
3487 * protected section without being interrupted. So there is no
3488 * real need to boost.
3490 if (unlikely(p
== rq
->idle
)) {
3491 WARN_ON(p
!= rq
->curr
);
3492 WARN_ON(p
->pi_blocked_on
);
3496 trace_sched_pi_setprio(p
, prio
);
3498 prev_class
= p
->sched_class
;
3499 queued
= task_on_rq_queued(p
);
3500 running
= task_current(rq
, p
);
3502 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
3504 put_prev_task(rq
, p
);
3507 * Boosting condition are:
3508 * 1. -rt task is running and holds mutex A
3509 * --> -dl task blocks on mutex A
3511 * 2. -dl task is running and holds mutex A
3512 * --> -dl task blocks on mutex A and could preempt the
3515 if (dl_prio(prio
)) {
3516 struct task_struct
*pi_task
= rt_mutex_get_top_task(p
);
3517 if (!dl_prio(p
->normal_prio
) ||
3518 (pi_task
&& dl_entity_preempt(&pi_task
->dl
, &p
->dl
))) {
3519 p
->dl
.dl_boosted
= 1;
3520 enqueue_flag
|= ENQUEUE_REPLENISH
;
3522 p
->dl
.dl_boosted
= 0;
3523 p
->sched_class
= &dl_sched_class
;
3524 } else if (rt_prio(prio
)) {
3525 if (dl_prio(oldprio
))
3526 p
->dl
.dl_boosted
= 0;
3528 enqueue_flag
|= ENQUEUE_HEAD
;
3529 p
->sched_class
= &rt_sched_class
;
3531 if (dl_prio(oldprio
))
3532 p
->dl
.dl_boosted
= 0;
3533 if (rt_prio(oldprio
))
3535 p
->sched_class
= &fair_sched_class
;
3541 p
->sched_class
->set_curr_task(rq
);
3543 enqueue_task(rq
, p
, enqueue_flag
);
3545 check_class_changed(rq
, p
, prev_class
, oldprio
);
3547 preempt_disable(); /* avoid rq from going away on us */
3548 __task_rq_unlock(rq
);
3550 balance_callback(rq
);
3555 void set_user_nice(struct task_struct
*p
, long nice
)
3557 int old_prio
, delta
, queued
;
3558 unsigned long flags
;
3561 if (task_nice(p
) == nice
|| nice
< MIN_NICE
|| nice
> MAX_NICE
)
3564 * We have to be careful, if called from sys_setpriority(),
3565 * the task might be in the middle of scheduling on another CPU.
3567 rq
= task_rq_lock(p
, &flags
);
3569 * The RT priorities are set via sched_setscheduler(), but we still
3570 * allow the 'normal' nice value to be set - but as expected
3571 * it wont have any effect on scheduling until the task is
3572 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
3574 if (task_has_dl_policy(p
) || task_has_rt_policy(p
)) {
3575 p
->static_prio
= NICE_TO_PRIO(nice
);
3578 queued
= task_on_rq_queued(p
);
3580 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
3582 p
->static_prio
= NICE_TO_PRIO(nice
);
3585 p
->prio
= effective_prio(p
);
3586 delta
= p
->prio
- old_prio
;
3589 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
3591 * If the task increased its priority or is running and
3592 * lowered its priority, then reschedule its CPU:
3594 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3598 task_rq_unlock(rq
, p
, &flags
);
3600 EXPORT_SYMBOL(set_user_nice
);
3603 * can_nice - check if a task can reduce its nice value
3607 int can_nice(const struct task_struct
*p
, const int nice
)
3609 /* convert nice value [19,-20] to rlimit style value [1,40] */
3610 int nice_rlim
= nice_to_rlimit(nice
);
3612 return (nice_rlim
<= task_rlimit(p
, RLIMIT_NICE
) ||
3613 capable(CAP_SYS_NICE
));
3616 #ifdef __ARCH_WANT_SYS_NICE
3619 * sys_nice - change the priority of the current process.
3620 * @increment: priority increment
3622 * sys_setpriority is a more generic, but much slower function that
3623 * does similar things.
3625 SYSCALL_DEFINE1(nice
, int, increment
)
3630 * Setpriority might change our priority at the same moment.
3631 * We don't have to worry. Conceptually one call occurs first
3632 * and we have a single winner.
3634 increment
= clamp(increment
, -NICE_WIDTH
, NICE_WIDTH
);
3635 nice
= task_nice(current
) + increment
;
3637 nice
= clamp_val(nice
, MIN_NICE
, MAX_NICE
);
3638 if (increment
< 0 && !can_nice(current
, nice
))
3641 retval
= security_task_setnice(current
, nice
);
3645 set_user_nice(current
, nice
);
3652 * task_prio - return the priority value of a given task.
3653 * @p: the task in question.
3655 * Return: The priority value as seen by users in /proc.
3656 * RT tasks are offset by -200. Normal tasks are centered
3657 * around 0, value goes from -16 to +15.
3659 int task_prio(const struct task_struct
*p
)
3661 return p
->prio
- MAX_RT_PRIO
;
3665 * idle_cpu - is a given cpu idle currently?
3666 * @cpu: the processor in question.
3668 * Return: 1 if the CPU is currently idle. 0 otherwise.
3670 int idle_cpu(int cpu
)
3672 struct rq
*rq
= cpu_rq(cpu
);
3674 if (rq
->curr
!= rq
->idle
)
3681 if (!llist_empty(&rq
->wake_list
))
3689 * idle_task - return the idle task for a given cpu.
3690 * @cpu: the processor in question.
3692 * Return: The idle task for the cpu @cpu.
3694 struct task_struct
*idle_task(int cpu
)
3696 return cpu_rq(cpu
)->idle
;
3700 * find_process_by_pid - find a process with a matching PID value.
3701 * @pid: the pid in question.
3703 * The task of @pid, if found. %NULL otherwise.
3705 static struct task_struct
*find_process_by_pid(pid_t pid
)
3707 return pid
? find_task_by_vpid(pid
) : current
;
3711 * This function initializes the sched_dl_entity of a newly becoming
3712 * SCHED_DEADLINE task.
3714 * Only the static values are considered here, the actual runtime and the
3715 * absolute deadline will be properly calculated when the task is enqueued
3716 * for the first time with its new policy.
3719 __setparam_dl(struct task_struct
*p
, const struct sched_attr
*attr
)
3721 struct sched_dl_entity
*dl_se
= &p
->dl
;
3723 dl_se
->dl_runtime
= attr
->sched_runtime
;
3724 dl_se
->dl_deadline
= attr
->sched_deadline
;
3725 dl_se
->dl_period
= attr
->sched_period
?: dl_se
->dl_deadline
;
3726 dl_se
->flags
= attr
->sched_flags
;
3727 dl_se
->dl_bw
= to_ratio(dl_se
->dl_period
, dl_se
->dl_runtime
);
3730 * Changing the parameters of a task is 'tricky' and we're not doing
3731 * the correct thing -- also see task_dead_dl() and switched_from_dl().
3733 * What we SHOULD do is delay the bandwidth release until the 0-lag
3734 * point. This would include retaining the task_struct until that time
3735 * and change dl_overflow() to not immediately decrement the current
3738 * Instead we retain the current runtime/deadline and let the new
3739 * parameters take effect after the current reservation period lapses.
3740 * This is safe (albeit pessimistic) because the 0-lag point is always
3741 * before the current scheduling deadline.
3743 * We can still have temporary overloads because we do not delay the
3744 * change in bandwidth until that time; so admission control is
3745 * not on the safe side. It does however guarantee tasks will never
3746 * consume more than promised.
3751 * sched_setparam() passes in -1 for its policy, to let the functions
3752 * it calls know not to change it.
3754 #define SETPARAM_POLICY -1
3756 static void __setscheduler_params(struct task_struct
*p
,
3757 const struct sched_attr
*attr
)
3759 int policy
= attr
->sched_policy
;
3761 if (policy
== SETPARAM_POLICY
)
3766 if (dl_policy(policy
))
3767 __setparam_dl(p
, attr
);
3768 else if (fair_policy(policy
))
3769 p
->static_prio
= NICE_TO_PRIO(attr
->sched_nice
);
3772 * __sched_setscheduler() ensures attr->sched_priority == 0 when
3773 * !rt_policy. Always setting this ensures that things like
3774 * getparam()/getattr() don't report silly values for !rt tasks.
3776 p
->rt_priority
= attr
->sched_priority
;
3777 p
->normal_prio
= normal_prio(p
);
3781 /* Actually do priority change: must hold pi & rq lock. */
3782 static void __setscheduler(struct rq
*rq
, struct task_struct
*p
,
3783 const struct sched_attr
*attr
, bool keep_boost
)
3785 __setscheduler_params(p
, attr
);
3788 * Keep a potential priority boosting if called from
3789 * sched_setscheduler().
3792 p
->prio
= rt_mutex_get_effective_prio(p
, normal_prio(p
));
3794 p
->prio
= normal_prio(p
);
3796 if (dl_prio(p
->prio
))
3797 p
->sched_class
= &dl_sched_class
;
3798 else if (rt_prio(p
->prio
))
3799 p
->sched_class
= &rt_sched_class
;
3801 p
->sched_class
= &fair_sched_class
;
3805 __getparam_dl(struct task_struct
*p
, struct sched_attr
*attr
)
3807 struct sched_dl_entity
*dl_se
= &p
->dl
;
3809 attr
->sched_priority
= p
->rt_priority
;
3810 attr
->sched_runtime
= dl_se
->dl_runtime
;
3811 attr
->sched_deadline
= dl_se
->dl_deadline
;
3812 attr
->sched_period
= dl_se
->dl_period
;
3813 attr
->sched_flags
= dl_se
->flags
;
3817 * This function validates the new parameters of a -deadline task.
3818 * We ask for the deadline not being zero, and greater or equal
3819 * than the runtime, as well as the period of being zero or
3820 * greater than deadline. Furthermore, we have to be sure that
3821 * user parameters are above the internal resolution of 1us (we
3822 * check sched_runtime only since it is always the smaller one) and
3823 * below 2^63 ns (we have to check both sched_deadline and
3824 * sched_period, as the latter can be zero).
3827 __checkparam_dl(const struct sched_attr
*attr
)
3830 if (attr
->sched_deadline
== 0)
3834 * Since we truncate DL_SCALE bits, make sure we're at least
3837 if (attr
->sched_runtime
< (1ULL << DL_SCALE
))
3841 * Since we use the MSB for wrap-around and sign issues, make
3842 * sure it's not set (mind that period can be equal to zero).
3844 if (attr
->sched_deadline
& (1ULL << 63) ||
3845 attr
->sched_period
& (1ULL << 63))
3848 /* runtime <= deadline <= period (if period != 0) */
3849 if ((attr
->sched_period
!= 0 &&
3850 attr
->sched_period
< attr
->sched_deadline
) ||
3851 attr
->sched_deadline
< attr
->sched_runtime
)
3858 * check the target process has a UID that matches the current process's
3860 static bool check_same_owner(struct task_struct
*p
)
3862 const struct cred
*cred
= current_cred(), *pcred
;
3866 pcred
= __task_cred(p
);
3867 match
= (uid_eq(cred
->euid
, pcred
->euid
) ||
3868 uid_eq(cred
->euid
, pcred
->uid
));
3873 static bool dl_param_changed(struct task_struct
*p
,
3874 const struct sched_attr
*attr
)
3876 struct sched_dl_entity
*dl_se
= &p
->dl
;
3878 if (dl_se
->dl_runtime
!= attr
->sched_runtime
||
3879 dl_se
->dl_deadline
!= attr
->sched_deadline
||
3880 dl_se
->dl_period
!= attr
->sched_period
||
3881 dl_se
->flags
!= attr
->sched_flags
)
3887 static int __sched_setscheduler(struct task_struct
*p
,
3888 const struct sched_attr
*attr
,
3891 int newprio
= dl_policy(attr
->sched_policy
) ? MAX_DL_PRIO
- 1 :
3892 MAX_RT_PRIO
- 1 - attr
->sched_priority
;
3893 int retval
, oldprio
, oldpolicy
= -1, queued
, running
;
3894 int new_effective_prio
, policy
= attr
->sched_policy
;
3895 unsigned long flags
;
3896 const struct sched_class
*prev_class
;
3900 /* may grab non-irq protected spin_locks */
3901 BUG_ON(in_interrupt());
3903 /* double check policy once rq lock held */
3905 reset_on_fork
= p
->sched_reset_on_fork
;
3906 policy
= oldpolicy
= p
->policy
;
3908 reset_on_fork
= !!(attr
->sched_flags
& SCHED_FLAG_RESET_ON_FORK
);
3910 if (!valid_policy(policy
))
3914 if (attr
->sched_flags
& ~(SCHED_FLAG_RESET_ON_FORK
))
3918 * Valid priorities for SCHED_FIFO and SCHED_RR are
3919 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3920 * SCHED_BATCH and SCHED_IDLE is 0.
3922 if ((p
->mm
&& attr
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3923 (!p
->mm
&& attr
->sched_priority
> MAX_RT_PRIO
-1))
3925 if ((dl_policy(policy
) && !__checkparam_dl(attr
)) ||
3926 (rt_policy(policy
) != (attr
->sched_priority
!= 0)))
3930 * Allow unprivileged RT tasks to decrease priority:
3932 if (user
&& !capable(CAP_SYS_NICE
)) {
3933 if (fair_policy(policy
)) {
3934 if (attr
->sched_nice
< task_nice(p
) &&
3935 !can_nice(p
, attr
->sched_nice
))
3939 if (rt_policy(policy
)) {
3940 unsigned long rlim_rtprio
=
3941 task_rlimit(p
, RLIMIT_RTPRIO
);
3943 /* can't set/change the rt policy */
3944 if (policy
!= p
->policy
&& !rlim_rtprio
)
3947 /* can't increase priority */
3948 if (attr
->sched_priority
> p
->rt_priority
&&
3949 attr
->sched_priority
> rlim_rtprio
)
3954 * Can't set/change SCHED_DEADLINE policy at all for now
3955 * (safest behavior); in the future we would like to allow
3956 * unprivileged DL tasks to increase their relative deadline
3957 * or reduce their runtime (both ways reducing utilization)
3959 if (dl_policy(policy
))
3963 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3964 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3966 if (idle_policy(p
->policy
) && !idle_policy(policy
)) {
3967 if (!can_nice(p
, task_nice(p
)))
3971 /* can't change other user's priorities */
3972 if (!check_same_owner(p
))
3975 /* Normal users shall not reset the sched_reset_on_fork flag */
3976 if (p
->sched_reset_on_fork
&& !reset_on_fork
)
3981 retval
= security_task_setscheduler(p
);
3987 * make sure no PI-waiters arrive (or leave) while we are
3988 * changing the priority of the task:
3990 * To be able to change p->policy safely, the appropriate
3991 * runqueue lock must be held.
3993 rq
= task_rq_lock(p
, &flags
);
3996 * Changing the policy of the stop threads its a very bad idea
3998 if (p
== rq
->stop
) {
3999 task_rq_unlock(rq
, p
, &flags
);
4004 * If not changing anything there's no need to proceed further,
4005 * but store a possible modification of reset_on_fork.
4007 if (unlikely(policy
== p
->policy
)) {
4008 if (fair_policy(policy
) && attr
->sched_nice
!= task_nice(p
))
4010 if (rt_policy(policy
) && attr
->sched_priority
!= p
->rt_priority
)
4012 if (dl_policy(policy
) && dl_param_changed(p
, attr
))
4015 p
->sched_reset_on_fork
= reset_on_fork
;
4016 task_rq_unlock(rq
, p
, &flags
);
4022 #ifdef CONFIG_RT_GROUP_SCHED
4024 * Do not allow realtime tasks into groups that have no runtime
4027 if (rt_bandwidth_enabled() && rt_policy(policy
) &&
4028 task_group(p
)->rt_bandwidth
.rt_runtime
== 0 &&
4029 !task_group_is_autogroup(task_group(p
))) {
4030 task_rq_unlock(rq
, p
, &flags
);
4035 if (dl_bandwidth_enabled() && dl_policy(policy
)) {
4036 cpumask_t
*span
= rq
->rd
->span
;
4039 * Don't allow tasks with an affinity mask smaller than
4040 * the entire root_domain to become SCHED_DEADLINE. We
4041 * will also fail if there's no bandwidth available.
4043 if (!cpumask_subset(span
, &p
->cpus_allowed
) ||
4044 rq
->rd
->dl_bw
.bw
== 0) {
4045 task_rq_unlock(rq
, p
, &flags
);
4052 /* recheck policy now with rq lock held */
4053 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4054 policy
= oldpolicy
= -1;
4055 task_rq_unlock(rq
, p
, &flags
);
4060 * If setscheduling to SCHED_DEADLINE (or changing the parameters
4061 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
4064 if ((dl_policy(policy
) || dl_task(p
)) && dl_overflow(p
, policy
, attr
)) {
4065 task_rq_unlock(rq
, p
, &flags
);
4069 p
->sched_reset_on_fork
= reset_on_fork
;
4074 * Take priority boosted tasks into account. If the new
4075 * effective priority is unchanged, we just store the new
4076 * normal parameters and do not touch the scheduler class and
4077 * the runqueue. This will be done when the task deboost
4080 new_effective_prio
= rt_mutex_get_effective_prio(p
, newprio
);
4081 if (new_effective_prio
== oldprio
) {
4082 __setscheduler_params(p
, attr
);
4083 task_rq_unlock(rq
, p
, &flags
);
4088 queued
= task_on_rq_queued(p
);
4089 running
= task_current(rq
, p
);
4091 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
4093 put_prev_task(rq
, p
);
4095 prev_class
= p
->sched_class
;
4096 __setscheduler(rq
, p
, attr
, pi
);
4099 p
->sched_class
->set_curr_task(rq
);
4101 int enqueue_flags
= ENQUEUE_RESTORE
;
4103 * We enqueue to tail when the priority of a task is
4104 * increased (user space view).
4106 if (oldprio
<= p
->prio
)
4107 enqueue_flags
|= ENQUEUE_HEAD
;
4109 enqueue_task(rq
, p
, enqueue_flags
);
4112 check_class_changed(rq
, p
, prev_class
, oldprio
);
4113 preempt_disable(); /* avoid rq from going away on us */
4114 task_rq_unlock(rq
, p
, &flags
);
4117 rt_mutex_adjust_pi(p
);
4120 * Run balance callbacks after we've adjusted the PI chain.
4122 balance_callback(rq
);
4128 static int _sched_setscheduler(struct task_struct
*p
, int policy
,
4129 const struct sched_param
*param
, bool check
)
4131 struct sched_attr attr
= {
4132 .sched_policy
= policy
,
4133 .sched_priority
= param
->sched_priority
,
4134 .sched_nice
= PRIO_TO_NICE(p
->static_prio
),
4137 /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
4138 if ((policy
!= SETPARAM_POLICY
) && (policy
& SCHED_RESET_ON_FORK
)) {
4139 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
4140 policy
&= ~SCHED_RESET_ON_FORK
;
4141 attr
.sched_policy
= policy
;
4144 return __sched_setscheduler(p
, &attr
, check
, true);
4147 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4148 * @p: the task in question.
4149 * @policy: new policy.
4150 * @param: structure containing the new RT priority.
4152 * Return: 0 on success. An error code otherwise.
4154 * NOTE that the task may be already dead.
4156 int sched_setscheduler(struct task_struct
*p
, int policy
,
4157 const struct sched_param
*param
)
4159 return _sched_setscheduler(p
, policy
, param
, true);
4161 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4163 int sched_setattr(struct task_struct
*p
, const struct sched_attr
*attr
)
4165 return __sched_setscheduler(p
, attr
, true, true);
4167 EXPORT_SYMBOL_GPL(sched_setattr
);
4170 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4171 * @p: the task in question.
4172 * @policy: new policy.
4173 * @param: structure containing the new RT priority.
4175 * Just like sched_setscheduler, only don't bother checking if the
4176 * current context has permission. For example, this is needed in
4177 * stop_machine(): we create temporary high priority worker threads,
4178 * but our caller might not have that capability.
4180 * Return: 0 on success. An error code otherwise.
4182 int sched_setscheduler_nocheck(struct task_struct
*p
, int policy
,
4183 const struct sched_param
*param
)
4185 return _sched_setscheduler(p
, policy
, param
, false);
4187 EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck
);
4190 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4192 struct sched_param lparam
;
4193 struct task_struct
*p
;
4196 if (!param
|| pid
< 0)
4198 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4203 p
= find_process_by_pid(pid
);
4205 retval
= sched_setscheduler(p
, policy
, &lparam
);
4212 * Mimics kernel/events/core.c perf_copy_attr().
4214 static int sched_copy_attr(struct sched_attr __user
*uattr
,
4215 struct sched_attr
*attr
)
4220 if (!access_ok(VERIFY_WRITE
, uattr
, SCHED_ATTR_SIZE_VER0
))
4224 * zero the full structure, so that a short copy will be nice.
4226 memset(attr
, 0, sizeof(*attr
));
4228 ret
= get_user(size
, &uattr
->size
);
4232 if (size
> PAGE_SIZE
) /* silly large */
4235 if (!size
) /* abi compat */
4236 size
= SCHED_ATTR_SIZE_VER0
;
4238 if (size
< SCHED_ATTR_SIZE_VER0
)
4242 * If we're handed a bigger struct than we know of,
4243 * ensure all the unknown bits are 0 - i.e. new
4244 * user-space does not rely on any kernel feature
4245 * extensions we dont know about yet.
4247 if (size
> sizeof(*attr
)) {
4248 unsigned char __user
*addr
;
4249 unsigned char __user
*end
;
4252 addr
= (void __user
*)uattr
+ sizeof(*attr
);
4253 end
= (void __user
*)uattr
+ size
;
4255 for (; addr
< end
; addr
++) {
4256 ret
= get_user(val
, addr
);
4262 size
= sizeof(*attr
);
4265 ret
= copy_from_user(attr
, uattr
, size
);
4270 * XXX: do we want to be lenient like existing syscalls; or do we want
4271 * to be strict and return an error on out-of-bounds values?
4273 attr
->sched_nice
= clamp(attr
->sched_nice
, MIN_NICE
, MAX_NICE
);
4278 put_user(sizeof(*attr
), &uattr
->size
);
4283 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4284 * @pid: the pid in question.
4285 * @policy: new policy.
4286 * @param: structure containing the new RT priority.
4288 * Return: 0 on success. An error code otherwise.
4290 SYSCALL_DEFINE3(sched_setscheduler
, pid_t
, pid
, int, policy
,
4291 struct sched_param __user
*, param
)
4293 /* negative values for policy are not valid */
4297 return do_sched_setscheduler(pid
, policy
, param
);
4301 * sys_sched_setparam - set/change the RT priority of a thread
4302 * @pid: the pid in question.
4303 * @param: structure containing the new RT priority.
4305 * Return: 0 on success. An error code otherwise.
4307 SYSCALL_DEFINE2(sched_setparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4309 return do_sched_setscheduler(pid
, SETPARAM_POLICY
, param
);
4313 * sys_sched_setattr - same as above, but with extended sched_attr
4314 * @pid: the pid in question.
4315 * @uattr: structure containing the extended parameters.
4316 * @flags: for future extension.
4318 SYSCALL_DEFINE3(sched_setattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
4319 unsigned int, flags
)
4321 struct sched_attr attr
;
4322 struct task_struct
*p
;
4325 if (!uattr
|| pid
< 0 || flags
)
4328 retval
= sched_copy_attr(uattr
, &attr
);
4332 if ((int)attr
.sched_policy
< 0)
4337 p
= find_process_by_pid(pid
);
4339 retval
= sched_setattr(p
, &attr
);
4346 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4347 * @pid: the pid in question.
4349 * Return: On success, the policy of the thread. Otherwise, a negative error
4352 SYSCALL_DEFINE1(sched_getscheduler
, pid_t
, pid
)
4354 struct task_struct
*p
;
4362 p
= find_process_by_pid(pid
);
4364 retval
= security_task_getscheduler(p
);
4367 | (p
->sched_reset_on_fork
? SCHED_RESET_ON_FORK
: 0);
4374 * sys_sched_getparam - get the RT priority of a thread
4375 * @pid: the pid in question.
4376 * @param: structure containing the RT priority.
4378 * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
4381 SYSCALL_DEFINE2(sched_getparam
, pid_t
, pid
, struct sched_param __user
*, param
)
4383 struct sched_param lp
= { .sched_priority
= 0 };
4384 struct task_struct
*p
;
4387 if (!param
|| pid
< 0)
4391 p
= find_process_by_pid(pid
);
4396 retval
= security_task_getscheduler(p
);
4400 if (task_has_rt_policy(p
))
4401 lp
.sched_priority
= p
->rt_priority
;
4405 * This one might sleep, we cannot do it with a spinlock held ...
4407 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4416 static int sched_read_attr(struct sched_attr __user
*uattr
,
4417 struct sched_attr
*attr
,
4422 if (!access_ok(VERIFY_WRITE
, uattr
, usize
))
4426 * If we're handed a smaller struct than we know of,
4427 * ensure all the unknown bits are 0 - i.e. old
4428 * user-space does not get uncomplete information.
4430 if (usize
< sizeof(*attr
)) {
4431 unsigned char *addr
;
4434 addr
= (void *)attr
+ usize
;
4435 end
= (void *)attr
+ sizeof(*attr
);
4437 for (; addr
< end
; addr
++) {
4445 ret
= copy_to_user(uattr
, attr
, attr
->size
);
4453 * sys_sched_getattr - similar to sched_getparam, but with sched_attr
4454 * @pid: the pid in question.
4455 * @uattr: structure containing the extended parameters.
4456 * @size: sizeof(attr) for fwd/bwd comp.
4457 * @flags: for future extension.
4459 SYSCALL_DEFINE4(sched_getattr
, pid_t
, pid
, struct sched_attr __user
*, uattr
,
4460 unsigned int, size
, unsigned int, flags
)
4462 struct sched_attr attr
= {
4463 .size
= sizeof(struct sched_attr
),
4465 struct task_struct
*p
;
4468 if (!uattr
|| pid
< 0 || size
> PAGE_SIZE
||
4469 size
< SCHED_ATTR_SIZE_VER0
|| flags
)
4473 p
= find_process_by_pid(pid
);
4478 retval
= security_task_getscheduler(p
);
4482 attr
.sched_policy
= p
->policy
;
4483 if (p
->sched_reset_on_fork
)
4484 attr
.sched_flags
|= SCHED_FLAG_RESET_ON_FORK
;
4485 if (task_has_dl_policy(p
))
4486 __getparam_dl(p
, &attr
);
4487 else if (task_has_rt_policy(p
))
4488 attr
.sched_priority
= p
->rt_priority
;
4490 attr
.sched_nice
= task_nice(p
);
4494 retval
= sched_read_attr(uattr
, &attr
, size
);
4502 long sched_setaffinity(pid_t pid
, const struct cpumask
*in_mask
)
4504 cpumask_var_t cpus_allowed
, new_mask
;
4505 struct task_struct
*p
;
4510 p
= find_process_by_pid(pid
);
4516 /* Prevent p going away */
4520 if (p
->flags
& PF_NO_SETAFFINITY
) {
4524 if (!alloc_cpumask_var(&cpus_allowed
, GFP_KERNEL
)) {
4528 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
)) {
4530 goto out_free_cpus_allowed
;
4533 if (!check_same_owner(p
)) {
4535 if (!ns_capable(__task_cred(p
)->user_ns
, CAP_SYS_NICE
)) {
4537 goto out_free_new_mask
;
4542 retval
= security_task_setscheduler(p
);
4544 goto out_free_new_mask
;
4547 cpuset_cpus_allowed(p
, cpus_allowed
);
4548 cpumask_and(new_mask
, in_mask
, cpus_allowed
);
4551 * Since bandwidth control happens on root_domain basis,
4552 * if admission test is enabled, we only admit -deadline
4553 * tasks allowed to run on all the CPUs in the task's
4557 if (task_has_dl_policy(p
) && dl_bandwidth_enabled()) {
4559 if (!cpumask_subset(task_rq(p
)->rd
->span
, new_mask
)) {
4562 goto out_free_new_mask
;
4568 retval
= __set_cpus_allowed_ptr(p
, new_mask
, true);
4571 cpuset_cpus_allowed(p
, cpus_allowed
);
4572 if (!cpumask_subset(new_mask
, cpus_allowed
)) {
4574 * We must have raced with a concurrent cpuset
4575 * update. Just reset the cpus_allowed to the
4576 * cpuset's cpus_allowed
4578 cpumask_copy(new_mask
, cpus_allowed
);
4583 free_cpumask_var(new_mask
);
4584 out_free_cpus_allowed
:
4585 free_cpumask_var(cpus_allowed
);
4591 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4592 struct cpumask
*new_mask
)
4594 if (len
< cpumask_size())
4595 cpumask_clear(new_mask
);
4596 else if (len
> cpumask_size())
4597 len
= cpumask_size();
4599 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4603 * sys_sched_setaffinity - set the cpu affinity of a process
4604 * @pid: pid of the process
4605 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4606 * @user_mask_ptr: user-space pointer to the new cpu mask
4608 * Return: 0 on success. An error code otherwise.
4610 SYSCALL_DEFINE3(sched_setaffinity
, pid_t
, pid
, unsigned int, len
,
4611 unsigned long __user
*, user_mask_ptr
)
4613 cpumask_var_t new_mask
;
4616 if (!alloc_cpumask_var(&new_mask
, GFP_KERNEL
))
4619 retval
= get_user_cpu_mask(user_mask_ptr
, len
, new_mask
);
4621 retval
= sched_setaffinity(pid
, new_mask
);
4622 free_cpumask_var(new_mask
);
4626 long sched_getaffinity(pid_t pid
, struct cpumask
*mask
)
4628 struct task_struct
*p
;
4629 unsigned long flags
;
4635 p
= find_process_by_pid(pid
);
4639 retval
= security_task_getscheduler(p
);
4643 raw_spin_lock_irqsave(&p
->pi_lock
, flags
);
4644 cpumask_and(mask
, &p
->cpus_allowed
, cpu_active_mask
);
4645 raw_spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4654 * sys_sched_getaffinity - get the cpu affinity of a process
4655 * @pid: pid of the process
4656 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4657 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4659 * Return: 0 on success. An error code otherwise.
4661 SYSCALL_DEFINE3(sched_getaffinity
, pid_t
, pid
, unsigned int, len
,
4662 unsigned long __user
*, user_mask_ptr
)
4667 if ((len
* BITS_PER_BYTE
) < nr_cpu_ids
)
4669 if (len
& (sizeof(unsigned long)-1))
4672 if (!alloc_cpumask_var(&mask
, GFP_KERNEL
))
4675 ret
= sched_getaffinity(pid
, mask
);
4677 size_t retlen
= min_t(size_t, len
, cpumask_size());
4679 if (copy_to_user(user_mask_ptr
, mask
, retlen
))
4684 free_cpumask_var(mask
);
4690 * sys_sched_yield - yield the current processor to other threads.
4692 * This function yields the current CPU to other tasks. If there are no
4693 * other threads running on this CPU then this function will return.
4697 SYSCALL_DEFINE0(sched_yield
)
4699 struct rq
*rq
= this_rq_lock();
4701 schedstat_inc(rq
, yld_count
);
4702 current
->sched_class
->yield_task(rq
);
4705 * Since we are going to call schedule() anyway, there's
4706 * no need to preempt or enable interrupts:
4708 __release(rq
->lock
);
4709 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4710 do_raw_spin_unlock(&rq
->lock
);
4711 sched_preempt_enable_no_resched();
4718 int __sched
_cond_resched(void)
4720 if (should_resched(0)) {
4721 preempt_schedule_common();
4726 EXPORT_SYMBOL(_cond_resched
);
4729 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4730 * call schedule, and on return reacquire the lock.
4732 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4733 * operations here to prevent schedule() from being called twice (once via
4734 * spin_unlock(), once by hand).
4736 int __cond_resched_lock(spinlock_t
*lock
)
4738 int resched
= should_resched(PREEMPT_LOCK_OFFSET
);
4741 lockdep_assert_held(lock
);
4743 if (spin_needbreak(lock
) || resched
) {
4746 preempt_schedule_common();
4754 EXPORT_SYMBOL(__cond_resched_lock
);
4756 int __sched
__cond_resched_softirq(void)
4758 BUG_ON(!in_softirq());
4760 if (should_resched(SOFTIRQ_DISABLE_OFFSET
)) {
4762 preempt_schedule_common();
4768 EXPORT_SYMBOL(__cond_resched_softirq
);
4771 * yield - yield the current processor to other threads.
4773 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4775 * The scheduler is at all times free to pick the calling task as the most
4776 * eligible task to run, if removing the yield() call from your code breaks
4777 * it, its already broken.
4779 * Typical broken usage is:
4784 * where one assumes that yield() will let 'the other' process run that will
4785 * make event true. If the current task is a SCHED_FIFO task that will never
4786 * happen. Never use yield() as a progress guarantee!!
4788 * If you want to use yield() to wait for something, use wait_event().
4789 * If you want to use yield() to be 'nice' for others, use cond_resched().
4790 * If you still want to use yield(), do not!
4792 void __sched
yield(void)
4794 set_current_state(TASK_RUNNING
);
4797 EXPORT_SYMBOL(yield
);
4800 * yield_to - yield the current processor to another thread in
4801 * your thread group, or accelerate that thread toward the
4802 * processor it's on.
4804 * @preempt: whether task preemption is allowed or not
4806 * It's the caller's job to ensure that the target task struct
4807 * can't go away on us before we can do any checks.
4810 * true (>0) if we indeed boosted the target task.
4811 * false (0) if we failed to boost the target.
4812 * -ESRCH if there's no task to yield to.
4814 int __sched
yield_to(struct task_struct
*p
, bool preempt
)
4816 struct task_struct
*curr
= current
;
4817 struct rq
*rq
, *p_rq
;
4818 unsigned long flags
;
4821 local_irq_save(flags
);
4827 * If we're the only runnable task on the rq and target rq also
4828 * has only one task, there's absolutely no point in yielding.
4830 if (rq
->nr_running
== 1 && p_rq
->nr_running
== 1) {
4835 double_rq_lock(rq
, p_rq
);
4836 if (task_rq(p
) != p_rq
) {
4837 double_rq_unlock(rq
, p_rq
);
4841 if (!curr
->sched_class
->yield_to_task
)
4844 if (curr
->sched_class
!= p
->sched_class
)
4847 if (task_running(p_rq
, p
) || p
->state
)
4850 yielded
= curr
->sched_class
->yield_to_task(rq
, p
, preempt
);
4852 schedstat_inc(rq
, yld_count
);
4854 * Make p's CPU reschedule; pick_next_entity takes care of
4857 if (preempt
&& rq
!= p_rq
)
4862 double_rq_unlock(rq
, p_rq
);
4864 local_irq_restore(flags
);
4871 EXPORT_SYMBOL_GPL(yield_to
);
4874 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4875 * that process accounting knows that this is a task in IO wait state.
4877 long __sched
io_schedule_timeout(long timeout
)
4879 int old_iowait
= current
->in_iowait
;
4883 current
->in_iowait
= 1;
4884 blk_schedule_flush_plug(current
);
4886 delayacct_blkio_start();
4888 atomic_inc(&rq
->nr_iowait
);
4889 ret
= schedule_timeout(timeout
);
4890 current
->in_iowait
= old_iowait
;
4891 atomic_dec(&rq
->nr_iowait
);
4892 delayacct_blkio_end();
4896 EXPORT_SYMBOL(io_schedule_timeout
);
4899 * sys_sched_get_priority_max - return maximum RT priority.
4900 * @policy: scheduling class.
4902 * Return: On success, this syscall returns the maximum
4903 * rt_priority that can be used by a given scheduling class.
4904 * On failure, a negative error code is returned.
4906 SYSCALL_DEFINE1(sched_get_priority_max
, int, policy
)
4913 ret
= MAX_USER_RT_PRIO
-1;
4915 case SCHED_DEADLINE
:
4926 * sys_sched_get_priority_min - return minimum RT priority.
4927 * @policy: scheduling class.
4929 * Return: On success, this syscall returns the minimum
4930 * rt_priority that can be used by a given scheduling class.
4931 * On failure, a negative error code is returned.
4933 SYSCALL_DEFINE1(sched_get_priority_min
, int, policy
)
4942 case SCHED_DEADLINE
:
4952 * sys_sched_rr_get_interval - return the default timeslice of a process.
4953 * @pid: pid of the process.
4954 * @interval: userspace pointer to the timeslice value.
4956 * this syscall writes the default timeslice value of a given process
4957 * into the user-space timespec buffer. A value of '0' means infinity.
4959 * Return: On success, 0 and the timeslice is in @interval. Otherwise,
4962 SYSCALL_DEFINE2(sched_rr_get_interval
, pid_t
, pid
,
4963 struct timespec __user
*, interval
)
4965 struct task_struct
*p
;
4966 unsigned int time_slice
;
4967 unsigned long flags
;
4977 p
= find_process_by_pid(pid
);
4981 retval
= security_task_getscheduler(p
);
4985 rq
= task_rq_lock(p
, &flags
);
4987 if (p
->sched_class
->get_rr_interval
)
4988 time_slice
= p
->sched_class
->get_rr_interval(rq
, p
);
4989 task_rq_unlock(rq
, p
, &flags
);
4992 jiffies_to_timespec(time_slice
, &t
);
4993 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
5001 static const char stat_nam
[] = TASK_STATE_TO_CHAR_STR
;
5003 void sched_show_task(struct task_struct
*p
)
5005 unsigned long free
= 0;
5007 unsigned long state
= p
->state
;
5010 state
= __ffs(state
) + 1;
5011 printk(KERN_INFO
"%-15.15s %c", p
->comm
,
5012 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
5013 #if BITS_PER_LONG == 32
5014 if (state
== TASK_RUNNING
)
5015 printk(KERN_CONT
" running ");
5017 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
5019 if (state
== TASK_RUNNING
)
5020 printk(KERN_CONT
" running task ");
5022 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
5024 #ifdef CONFIG_DEBUG_STACK_USAGE
5025 free
= stack_not_used(p
);
5030 ppid
= task_pid_nr(rcu_dereference(p
->real_parent
));
5032 printk(KERN_CONT
"%5lu %5d %6d 0x%08lx\n", free
,
5033 task_pid_nr(p
), ppid
,
5034 (unsigned long)task_thread_info(p
)->flags
);
5036 print_worker_info(KERN_INFO
, p
);
5037 show_stack(p
, NULL
);
5040 void show_state_filter(unsigned long state_filter
)
5042 struct task_struct
*g
, *p
;
5044 #if BITS_PER_LONG == 32
5046 " task PC stack pid father\n");
5049 " task PC stack pid father\n");
5052 for_each_process_thread(g
, p
) {
5054 * reset the NMI-timeout, listing all files on a slow
5055 * console might take a lot of time:
5057 touch_nmi_watchdog();
5058 if (!state_filter
|| (p
->state
& state_filter
))
5062 touch_all_softlockup_watchdogs();
5064 #ifdef CONFIG_SCHED_DEBUG
5065 sysrq_sched_debug_show();
5069 * Only show locks if all tasks are dumped:
5072 debug_show_all_locks();
5075 void init_idle_bootup_task(struct task_struct
*idle
)
5077 idle
->sched_class
= &idle_sched_class
;
5081 * init_idle - set up an idle thread for a given CPU
5082 * @idle: task in question
5083 * @cpu: cpu the idle task belongs to
5085 * NOTE: this function does not set the idle thread's NEED_RESCHED
5086 * flag, to make booting more robust.
5088 void init_idle(struct task_struct
*idle
, int cpu
)
5090 struct rq
*rq
= cpu_rq(cpu
);
5091 unsigned long flags
;
5093 raw_spin_lock_irqsave(&idle
->pi_lock
, flags
);
5094 raw_spin_lock(&rq
->lock
);
5096 __sched_fork(0, idle
);
5097 idle
->state
= TASK_RUNNING
;
5098 idle
->se
.exec_start
= sched_clock();
5100 kasan_unpoison_task_stack(idle
);
5104 * Its possible that init_idle() gets called multiple times on a task,
5105 * in that case do_set_cpus_allowed() will not do the right thing.
5107 * And since this is boot we can forgo the serialization.
5109 set_cpus_allowed_common(idle
, cpumask_of(cpu
));
5112 * We're having a chicken and egg problem, even though we are
5113 * holding rq->lock, the cpu isn't yet set to this cpu so the
5114 * lockdep check in task_group() will fail.
5116 * Similar case to sched_fork(). / Alternatively we could
5117 * use task_rq_lock() here and obtain the other rq->lock.
5122 __set_task_cpu(idle
, cpu
);
5125 rq
->curr
= rq
->idle
= idle
;
5126 idle
->on_rq
= TASK_ON_RQ_QUEUED
;
5130 raw_spin_unlock(&rq
->lock
);
5131 raw_spin_unlock_irqrestore(&idle
->pi_lock
, flags
);
5133 /* Set the preempt count _outside_ the spinlocks! */
5134 init_idle_preempt_count(idle
, cpu
);
5137 * The idle tasks have their own, simple scheduling class:
5139 idle
->sched_class
= &idle_sched_class
;
5140 ftrace_graph_init_idle_task(idle
, cpu
);
5141 vtime_init_idle(idle
, cpu
);
5143 sprintf(idle
->comm
, "%s/%d", INIT_TASK_COMM
, cpu
);
5147 int cpuset_cpumask_can_shrink(const struct cpumask
*cur
,
5148 const struct cpumask
*trial
)
5150 int ret
= 1, trial_cpus
;
5151 struct dl_bw
*cur_dl_b
;
5152 unsigned long flags
;
5154 if (!cpumask_weight(cur
))
5157 rcu_read_lock_sched();
5158 cur_dl_b
= dl_bw_of(cpumask_any(cur
));
5159 trial_cpus
= cpumask_weight(trial
);
5161 raw_spin_lock_irqsave(&cur_dl_b
->lock
, flags
);
5162 if (cur_dl_b
->bw
!= -1 &&
5163 cur_dl_b
->bw
* trial_cpus
< cur_dl_b
->total_bw
)
5165 raw_spin_unlock_irqrestore(&cur_dl_b
->lock
, flags
);
5166 rcu_read_unlock_sched();
5171 int task_can_attach(struct task_struct
*p
,
5172 const struct cpumask
*cs_cpus_allowed
)
5177 * Kthreads which disallow setaffinity shouldn't be moved
5178 * to a new cpuset; we don't want to change their cpu
5179 * affinity and isolating such threads by their set of
5180 * allowed nodes is unnecessary. Thus, cpusets are not
5181 * applicable for such threads. This prevents checking for
5182 * success of set_cpus_allowed_ptr() on all attached tasks
5183 * before cpus_allowed may be changed.
5185 if (p
->flags
& PF_NO_SETAFFINITY
) {
5191 if (dl_task(p
) && !cpumask_intersects(task_rq(p
)->rd
->span
,
5193 unsigned int dest_cpu
= cpumask_any_and(cpu_active_mask
,
5198 unsigned long flags
;
5200 rcu_read_lock_sched();
5201 dl_b
= dl_bw_of(dest_cpu
);
5202 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
5203 cpus
= dl_bw_cpus(dest_cpu
);
5204 overflow
= __dl_overflow(dl_b
, cpus
, 0, p
->dl
.dl_bw
);
5209 * We reserve space for this task in the destination
5210 * root_domain, as we can't fail after this point.
5211 * We will free resources in the source root_domain
5212 * later on (see set_cpus_allowed_dl()).
5214 __dl_add(dl_b
, p
->dl
.dl_bw
);
5216 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
5217 rcu_read_unlock_sched();
5227 #ifdef CONFIG_NUMA_BALANCING
5228 /* Migrate current task p to target_cpu */
5229 int migrate_task_to(struct task_struct
*p
, int target_cpu
)
5231 struct migration_arg arg
= { p
, target_cpu
};
5232 int curr_cpu
= task_cpu(p
);
5234 if (curr_cpu
== target_cpu
)
5237 if (!cpumask_test_cpu(target_cpu
, tsk_cpus_allowed(p
)))
5240 /* TODO: This is not properly updating schedstats */
5242 trace_sched_move_numa(p
, curr_cpu
, target_cpu
);
5243 return stop_one_cpu(curr_cpu
, migration_cpu_stop
, &arg
);
5247 * Requeue a task on a given node and accurately track the number of NUMA
5248 * tasks on the runqueues
5250 void sched_setnuma(struct task_struct
*p
, int nid
)
5253 unsigned long flags
;
5254 bool queued
, running
;
5256 rq
= task_rq_lock(p
, &flags
);
5257 queued
= task_on_rq_queued(p
);
5258 running
= task_current(rq
, p
);
5261 dequeue_task(rq
, p
, DEQUEUE_SAVE
);
5263 put_prev_task(rq
, p
);
5265 p
->numa_preferred_nid
= nid
;
5268 p
->sched_class
->set_curr_task(rq
);
5270 enqueue_task(rq
, p
, ENQUEUE_RESTORE
);
5271 task_rq_unlock(rq
, p
, &flags
);
5273 #endif /* CONFIG_NUMA_BALANCING */
5275 #ifdef CONFIG_HOTPLUG_CPU
5277 * Ensures that the idle task is using init_mm right before its cpu goes
5280 void idle_task_exit(void)
5282 struct mm_struct
*mm
= current
->active_mm
;
5284 BUG_ON(cpu_online(smp_processor_id()));
5286 if (mm
!= &init_mm
) {
5287 switch_mm(mm
, &init_mm
, current
);
5288 finish_arch_post_lock_switch();
5294 * Since this CPU is going 'away' for a while, fold any nr_active delta
5295 * we might have. Assumes we're called after migrate_tasks() so that the
5296 * nr_active count is stable.
5298 * Also see the comment "Global load-average calculations".
5300 static void calc_load_migrate(struct rq
*rq
)
5302 long delta
= calc_load_fold_active(rq
);
5304 atomic_long_add(delta
, &calc_load_tasks
);
5307 static void put_prev_task_fake(struct rq
*rq
, struct task_struct
*prev
)
5311 static const struct sched_class fake_sched_class
= {
5312 .put_prev_task
= put_prev_task_fake
,
5315 static struct task_struct fake_task
= {
5317 * Avoid pull_{rt,dl}_task()
5319 .prio
= MAX_PRIO
+ 1,
5320 .sched_class
= &fake_sched_class
,
5324 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5325 * try_to_wake_up()->select_task_rq().
5327 * Called with rq->lock held even though we'er in stop_machine() and
5328 * there's no concurrency possible, we hold the required locks anyway
5329 * because of lock validation efforts.
5331 static void migrate_tasks(struct rq
*dead_rq
)
5333 struct rq
*rq
= dead_rq
;
5334 struct task_struct
*next
, *stop
= rq
->stop
;
5338 * Fudge the rq selection such that the below task selection loop
5339 * doesn't get stuck on the currently eligible stop task.
5341 * We're currently inside stop_machine() and the rq is either stuck
5342 * in the stop_machine_cpu_stop() loop, or we're executing this code,
5343 * either way we should never end up calling schedule() until we're
5349 * put_prev_task() and pick_next_task() sched
5350 * class method both need to have an up-to-date
5351 * value of rq->clock[_task]
5353 update_rq_clock(rq
);
5357 * There's this thread running, bail when that's the only
5360 if (rq
->nr_running
== 1)
5364 * pick_next_task assumes pinned rq->lock.
5366 lockdep_pin_lock(&rq
->lock
);
5367 next
= pick_next_task(rq
, &fake_task
);
5369 next
->sched_class
->put_prev_task(rq
, next
);
5372 * Rules for changing task_struct::cpus_allowed are holding
5373 * both pi_lock and rq->lock, such that holding either
5374 * stabilizes the mask.
5376 * Drop rq->lock is not quite as disastrous as it usually is
5377 * because !cpu_active at this point, which means load-balance
5378 * will not interfere. Also, stop-machine.
5380 lockdep_unpin_lock(&rq
->lock
);
5381 raw_spin_unlock(&rq
->lock
);
5382 raw_spin_lock(&next
->pi_lock
);
5383 raw_spin_lock(&rq
->lock
);
5386 * Since we're inside stop-machine, _nothing_ should have
5387 * changed the task, WARN if weird stuff happened, because in
5388 * that case the above rq->lock drop is a fail too.
5390 if (WARN_ON(task_rq(next
) != rq
|| !task_on_rq_queued(next
))) {
5391 raw_spin_unlock(&next
->pi_lock
);
5395 /* Find suitable destination for @next, with force if needed. */
5396 dest_cpu
= select_fallback_rq(dead_rq
->cpu
, next
);
5398 rq
= __migrate_task(rq
, next
, dest_cpu
);
5399 if (rq
!= dead_rq
) {
5400 raw_spin_unlock(&rq
->lock
);
5402 raw_spin_lock(&rq
->lock
);
5404 raw_spin_unlock(&next
->pi_lock
);
5409 #endif /* CONFIG_HOTPLUG_CPU */
5411 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5413 static struct ctl_table sd_ctl_dir
[] = {
5415 .procname
= "sched_domain",
5421 static struct ctl_table sd_ctl_root
[] = {
5423 .procname
= "kernel",
5425 .child
= sd_ctl_dir
,
5430 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5432 struct ctl_table
*entry
=
5433 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5438 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5440 struct ctl_table
*entry
;
5443 * In the intermediate directories, both the child directory and
5444 * procname are dynamically allocated and could fail but the mode
5445 * will always be set. In the lowest directory the names are
5446 * static strings and all have proc handlers.
5448 for (entry
= *tablep
; entry
->mode
; entry
++) {
5450 sd_free_ctl_entry(&entry
->child
);
5451 if (entry
->proc_handler
== NULL
)
5452 kfree(entry
->procname
);
5459 static int min_load_idx
= 0;
5460 static int max_load_idx
= CPU_LOAD_IDX_MAX
-1;
5463 set_table_entry(struct ctl_table
*entry
,
5464 const char *procname
, void *data
, int maxlen
,
5465 umode_t mode
, proc_handler
*proc_handler
,
5468 entry
->procname
= procname
;
5470 entry
->maxlen
= maxlen
;
5472 entry
->proc_handler
= proc_handler
;
5475 entry
->extra1
= &min_load_idx
;
5476 entry
->extra2
= &max_load_idx
;
5480 static struct ctl_table
*
5481 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5483 struct ctl_table
*table
= sd_alloc_ctl_entry(14);
5488 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5489 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5490 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5491 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5492 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5493 sizeof(int), 0644, proc_dointvec_minmax
, true);
5494 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5495 sizeof(int), 0644, proc_dointvec_minmax
, true);
5496 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5497 sizeof(int), 0644, proc_dointvec_minmax
, true);
5498 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5499 sizeof(int), 0644, proc_dointvec_minmax
, true);
5500 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5501 sizeof(int), 0644, proc_dointvec_minmax
, true);
5502 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5503 sizeof(int), 0644, proc_dointvec_minmax
, false);
5504 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5505 sizeof(int), 0644, proc_dointvec_minmax
, false);
5506 set_table_entry(&table
[9], "cache_nice_tries",
5507 &sd
->cache_nice_tries
,
5508 sizeof(int), 0644, proc_dointvec_minmax
, false);
5509 set_table_entry(&table
[10], "flags", &sd
->flags
,
5510 sizeof(int), 0644, proc_dointvec_minmax
, false);
5511 set_table_entry(&table
[11], "max_newidle_lb_cost",
5512 &sd
->max_newidle_lb_cost
,
5513 sizeof(long), 0644, proc_doulongvec_minmax
, false);
5514 set_table_entry(&table
[12], "name", sd
->name
,
5515 CORENAME_MAX_SIZE
, 0444, proc_dostring
, false);
5516 /* &table[13] is terminator */
5521 static struct ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5523 struct ctl_table
*entry
, *table
;
5524 struct sched_domain
*sd
;
5525 int domain_num
= 0, i
;
5528 for_each_domain(cpu
, sd
)
5530 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5535 for_each_domain(cpu
, sd
) {
5536 snprintf(buf
, 32, "domain%d", i
);
5537 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5539 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5546 static struct ctl_table_header
*sd_sysctl_header
;
5547 static void register_sched_domain_sysctl(void)
5549 int i
, cpu_num
= num_possible_cpus();
5550 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5553 WARN_ON(sd_ctl_dir
[0].child
);
5554 sd_ctl_dir
[0].child
= entry
;
5559 for_each_possible_cpu(i
) {
5560 snprintf(buf
, 32, "cpu%d", i
);
5561 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5563 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5567 WARN_ON(sd_sysctl_header
);
5568 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5571 /* may be called multiple times per register */
5572 static void unregister_sched_domain_sysctl(void)
5574 unregister_sysctl_table(sd_sysctl_header
);
5575 sd_sysctl_header
= NULL
;
5576 if (sd_ctl_dir
[0].child
)
5577 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5580 static void register_sched_domain_sysctl(void)
5583 static void unregister_sched_domain_sysctl(void)
5586 #endif /* CONFIG_SCHED_DEBUG && CONFIG_SYSCTL */
5588 static void set_rq_online(struct rq
*rq
)
5591 const struct sched_class
*class;
5593 cpumask_set_cpu(rq
->cpu
, rq
->rd
->online
);
5596 for_each_class(class) {
5597 if (class->rq_online
)
5598 class->rq_online(rq
);
5603 static void set_rq_offline(struct rq
*rq
)
5606 const struct sched_class
*class;
5608 for_each_class(class) {
5609 if (class->rq_offline
)
5610 class->rq_offline(rq
);
5613 cpumask_clear_cpu(rq
->cpu
, rq
->rd
->online
);
5619 * migration_call - callback that gets triggered when a CPU is added.
5620 * Here we can start up the necessary migration thread for the new CPU.
5623 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5625 int cpu
= (long)hcpu
;
5626 unsigned long flags
;
5627 struct rq
*rq
= cpu_rq(cpu
);
5629 switch (action
& ~CPU_TASKS_FROZEN
) {
5631 case CPU_UP_PREPARE
:
5632 rq
->calc_load_update
= calc_load_update
;
5636 /* Update our root-domain */
5637 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5639 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5643 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5646 #ifdef CONFIG_HOTPLUG_CPU
5648 sched_ttwu_pending();
5649 /* Update our root-domain */
5650 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5652 BUG_ON(!cpumask_test_cpu(cpu
, rq
->rd
->span
));
5656 BUG_ON(rq
->nr_running
!= 1); /* the migration thread */
5657 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5661 calc_load_migrate(rq
);
5666 update_max_interval();
5672 * Register at high priority so that task migration (migrate_all_tasks)
5673 * happens before everything else. This has to be lower priority than
5674 * the notifier in the perf_event subsystem, though.
5676 static struct notifier_block migration_notifier
= {
5677 .notifier_call
= migration_call
,
5678 .priority
= CPU_PRI_MIGRATION
,
5681 static void set_cpu_rq_start_time(void)
5683 int cpu
= smp_processor_id();
5684 struct rq
*rq
= cpu_rq(cpu
);
5685 rq
->age_stamp
= sched_clock_cpu(cpu
);
5688 static int sched_cpu_active(struct notifier_block
*nfb
,
5689 unsigned long action
, void *hcpu
)
5691 int cpu
= (long)hcpu
;
5693 switch (action
& ~CPU_TASKS_FROZEN
) {
5695 set_cpu_rq_start_time();
5700 * At this point a starting CPU has marked itself as online via
5701 * set_cpu_online(). But it might not yet have marked itself
5702 * as active, which is essential from here on.
5704 set_cpu_active(cpu
, true);
5705 stop_machine_unpark(cpu
);
5708 case CPU_DOWN_FAILED
:
5709 set_cpu_active(cpu
, true);
5717 static int sched_cpu_inactive(struct notifier_block
*nfb
,
5718 unsigned long action
, void *hcpu
)
5720 switch (action
& ~CPU_TASKS_FROZEN
) {
5721 case CPU_DOWN_PREPARE
:
5722 set_cpu_active((long)hcpu
, false);
5729 static int __init
migration_init(void)
5731 void *cpu
= (void *)(long)smp_processor_id();
5734 /* Initialize migration for the boot CPU */
5735 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5736 BUG_ON(err
== NOTIFY_BAD
);
5737 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5738 register_cpu_notifier(&migration_notifier
);
5740 /* Register cpu active notifiers */
5741 cpu_notifier(sched_cpu_active
, CPU_PRI_SCHED_ACTIVE
);
5742 cpu_notifier(sched_cpu_inactive
, CPU_PRI_SCHED_INACTIVE
);
5746 early_initcall(migration_init
);
5748 static cpumask_var_t sched_domains_tmpmask
; /* sched_domains_mutex */
5750 #ifdef CONFIG_SCHED_DEBUG
5752 static __read_mostly
int sched_debug_enabled
;
5754 static int __init
sched_debug_setup(char *str
)
5756 sched_debug_enabled
= 1;
5760 early_param("sched_debug", sched_debug_setup
);
5762 static inline bool sched_debug(void)
5764 return sched_debug_enabled
;
5767 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
,
5768 struct cpumask
*groupmask
)
5770 struct sched_group
*group
= sd
->groups
;
5772 cpumask_clear(groupmask
);
5774 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5776 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5777 printk("does not load-balance\n");
5779 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5784 printk(KERN_CONT
"span %*pbl level %s\n",
5785 cpumask_pr_args(sched_domain_span(sd
)), sd
->name
);
5787 if (!cpumask_test_cpu(cpu
, sched_domain_span(sd
))) {
5788 printk(KERN_ERR
"ERROR: domain->span does not contain "
5791 if (!cpumask_test_cpu(cpu
, sched_group_cpus(group
))) {
5792 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5796 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5800 printk(KERN_ERR
"ERROR: group is NULL\n");
5804 if (!cpumask_weight(sched_group_cpus(group
))) {
5805 printk(KERN_CONT
"\n");
5806 printk(KERN_ERR
"ERROR: empty group\n");
5810 if (!(sd
->flags
& SD_OVERLAP
) &&
5811 cpumask_intersects(groupmask
, sched_group_cpus(group
))) {
5812 printk(KERN_CONT
"\n");
5813 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5817 cpumask_or(groupmask
, groupmask
, sched_group_cpus(group
));
5819 printk(KERN_CONT
" %*pbl",
5820 cpumask_pr_args(sched_group_cpus(group
)));
5821 if (group
->sgc
->capacity
!= SCHED_CAPACITY_SCALE
) {
5822 printk(KERN_CONT
" (cpu_capacity = %d)",
5823 group
->sgc
->capacity
);
5826 group
= group
->next
;
5827 } while (group
!= sd
->groups
);
5828 printk(KERN_CONT
"\n");
5830 if (!cpumask_equal(sched_domain_span(sd
), groupmask
))
5831 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5834 !cpumask_subset(groupmask
, sched_domain_span(sd
->parent
)))
5835 printk(KERN_ERR
"ERROR: parent span is not a superset "
5836 "of domain->span\n");
5840 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5844 if (!sched_debug_enabled
)
5848 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5852 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5855 if (sched_domain_debug_one(sd
, cpu
, level
, sched_domains_tmpmask
))
5863 #else /* !CONFIG_SCHED_DEBUG */
5864 # define sched_domain_debug(sd, cpu) do { } while (0)
5865 static inline bool sched_debug(void)
5869 #endif /* CONFIG_SCHED_DEBUG */
5871 static int sd_degenerate(struct sched_domain
*sd
)
5873 if (cpumask_weight(sched_domain_span(sd
)) == 1)
5876 /* Following flags need at least 2 groups */
5877 if (sd
->flags
& (SD_LOAD_BALANCE
|
5878 SD_BALANCE_NEWIDLE
|
5881 SD_SHARE_CPUCAPACITY
|
5882 SD_SHARE_PKG_RESOURCES
|
5883 SD_SHARE_POWERDOMAIN
)) {
5884 if (sd
->groups
!= sd
->groups
->next
)
5888 /* Following flags don't use groups */
5889 if (sd
->flags
& (SD_WAKE_AFFINE
))
5896 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5898 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5900 if (sd_degenerate(parent
))
5903 if (!cpumask_equal(sched_domain_span(sd
), sched_domain_span(parent
)))
5906 /* Flags needing groups don't count if only 1 group in parent */
5907 if (parent
->groups
== parent
->groups
->next
) {
5908 pflags
&= ~(SD_LOAD_BALANCE
|
5909 SD_BALANCE_NEWIDLE
|
5912 SD_SHARE_CPUCAPACITY
|
5913 SD_SHARE_PKG_RESOURCES
|
5915 SD_SHARE_POWERDOMAIN
);
5916 if (nr_node_ids
== 1)
5917 pflags
&= ~SD_SERIALIZE
;
5919 if (~cflags
& pflags
)
5925 static void free_rootdomain(struct rcu_head
*rcu
)
5927 struct root_domain
*rd
= container_of(rcu
, struct root_domain
, rcu
);
5929 cpupri_cleanup(&rd
->cpupri
);
5930 cpudl_cleanup(&rd
->cpudl
);
5931 free_cpumask_var(rd
->dlo_mask
);
5932 free_cpumask_var(rd
->rto_mask
);
5933 free_cpumask_var(rd
->online
);
5934 free_cpumask_var(rd
->span
);
5938 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
5940 struct root_domain
*old_rd
= NULL
;
5941 unsigned long flags
;
5943 raw_spin_lock_irqsave(&rq
->lock
, flags
);
5948 if (cpumask_test_cpu(rq
->cpu
, old_rd
->online
))
5951 cpumask_clear_cpu(rq
->cpu
, old_rd
->span
);
5954 * If we dont want to free the old_rd yet then
5955 * set old_rd to NULL to skip the freeing later
5958 if (!atomic_dec_and_test(&old_rd
->refcount
))
5962 atomic_inc(&rd
->refcount
);
5965 cpumask_set_cpu(rq
->cpu
, rd
->span
);
5966 if (cpumask_test_cpu(rq
->cpu
, cpu_active_mask
))
5969 raw_spin_unlock_irqrestore(&rq
->lock
, flags
);
5972 call_rcu_sched(&old_rd
->rcu
, free_rootdomain
);
5975 static int init_rootdomain(struct root_domain
*rd
)
5977 memset(rd
, 0, sizeof(*rd
));
5979 if (!zalloc_cpumask_var(&rd
->span
, GFP_KERNEL
))
5981 if (!zalloc_cpumask_var(&rd
->online
, GFP_KERNEL
))
5983 if (!zalloc_cpumask_var(&rd
->dlo_mask
, GFP_KERNEL
))
5985 if (!zalloc_cpumask_var(&rd
->rto_mask
, GFP_KERNEL
))
5988 init_dl_bw(&rd
->dl_bw
);
5989 if (cpudl_init(&rd
->cpudl
) != 0)
5992 if (cpupri_init(&rd
->cpupri
) != 0)
5997 free_cpumask_var(rd
->rto_mask
);
5999 free_cpumask_var(rd
->dlo_mask
);
6001 free_cpumask_var(rd
->online
);
6003 free_cpumask_var(rd
->span
);
6009 * By default the system creates a single root-domain with all cpus as
6010 * members (mimicking the global state we have today).
6012 struct root_domain def_root_domain
;
6014 static void init_defrootdomain(void)
6016 init_rootdomain(&def_root_domain
);
6018 atomic_set(&def_root_domain
.refcount
, 1);
6021 static struct root_domain
*alloc_rootdomain(void)
6023 struct root_domain
*rd
;
6025 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
6029 if (init_rootdomain(rd
) != 0) {
6037 static void free_sched_groups(struct sched_group
*sg
, int free_sgc
)
6039 struct sched_group
*tmp
, *first
;
6048 if (free_sgc
&& atomic_dec_and_test(&sg
->sgc
->ref
))
6053 } while (sg
!= first
);
6056 static void free_sched_domain(struct rcu_head
*rcu
)
6058 struct sched_domain
*sd
= container_of(rcu
, struct sched_domain
, rcu
);
6061 * If its an overlapping domain it has private groups, iterate and
6064 if (sd
->flags
& SD_OVERLAP
) {
6065 free_sched_groups(sd
->groups
, 1);
6066 } else if (atomic_dec_and_test(&sd
->groups
->ref
)) {
6067 kfree(sd
->groups
->sgc
);
6073 static void destroy_sched_domain(struct sched_domain
*sd
, int cpu
)
6075 call_rcu(&sd
->rcu
, free_sched_domain
);
6078 static void destroy_sched_domains(struct sched_domain
*sd
, int cpu
)
6080 for (; sd
; sd
= sd
->parent
)
6081 destroy_sched_domain(sd
, cpu
);
6085 * Keep a special pointer to the highest sched_domain that has
6086 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
6087 * allows us to avoid some pointer chasing select_idle_sibling().
6089 * Also keep a unique ID per domain (we use the first cpu number in
6090 * the cpumask of the domain), this allows us to quickly tell if
6091 * two cpus are in the same cache domain, see cpus_share_cache().
6093 DEFINE_PER_CPU(struct sched_domain
*, sd_llc
);
6094 DEFINE_PER_CPU(int, sd_llc_size
);
6095 DEFINE_PER_CPU(int, sd_llc_id
);
6096 DEFINE_PER_CPU(struct sched_domain
*, sd_numa
);
6097 DEFINE_PER_CPU(struct sched_domain
*, sd_busy
);
6098 DEFINE_PER_CPU(struct sched_domain
*, sd_asym
);
6100 static void update_top_cache_domain(int cpu
)
6102 struct sched_domain
*sd
;
6103 struct sched_domain
*busy_sd
= NULL
;
6107 sd
= highest_flag_domain(cpu
, SD_SHARE_PKG_RESOURCES
);
6109 id
= cpumask_first(sched_domain_span(sd
));
6110 size
= cpumask_weight(sched_domain_span(sd
));
6111 busy_sd
= sd
->parent
; /* sd_busy */
6113 rcu_assign_pointer(per_cpu(sd_busy
, cpu
), busy_sd
);
6115 rcu_assign_pointer(per_cpu(sd_llc
, cpu
), sd
);
6116 per_cpu(sd_llc_size
, cpu
) = size
;
6117 per_cpu(sd_llc_id
, cpu
) = id
;
6119 sd
= lowest_flag_domain(cpu
, SD_NUMA
);
6120 rcu_assign_pointer(per_cpu(sd_numa
, cpu
), sd
);
6122 sd
= highest_flag_domain(cpu
, SD_ASYM_PACKING
);
6123 rcu_assign_pointer(per_cpu(sd_asym
, cpu
), sd
);
6127 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6128 * hold the hotplug lock.
6131 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
6133 struct rq
*rq
= cpu_rq(cpu
);
6134 struct sched_domain
*tmp
;
6136 /* Remove the sched domains which do not contribute to scheduling. */
6137 for (tmp
= sd
; tmp
; ) {
6138 struct sched_domain
*parent
= tmp
->parent
;
6142 if (sd_parent_degenerate(tmp
, parent
)) {
6143 tmp
->parent
= parent
->parent
;
6145 parent
->parent
->child
= tmp
;
6147 * Transfer SD_PREFER_SIBLING down in case of a
6148 * degenerate parent; the spans match for this
6149 * so the property transfers.
6151 if (parent
->flags
& SD_PREFER_SIBLING
)
6152 tmp
->flags
|= SD_PREFER_SIBLING
;
6153 destroy_sched_domain(parent
, cpu
);
6158 if (sd
&& sd_degenerate(sd
)) {
6161 destroy_sched_domain(tmp
, cpu
);
6166 sched_domain_debug(sd
, cpu
);
6168 rq_attach_root(rq
, rd
);
6170 rcu_assign_pointer(rq
->sd
, sd
);
6171 destroy_sched_domains(tmp
, cpu
);
6173 update_top_cache_domain(cpu
);
6176 /* Setup the mask of cpus configured for isolated domains */
6177 static int __init
isolated_cpu_setup(char *str
)
6179 alloc_bootmem_cpumask_var(&cpu_isolated_map
);
6180 cpulist_parse(str
, cpu_isolated_map
);
6184 __setup("isolcpus=", isolated_cpu_setup
);
6187 struct sched_domain
** __percpu sd
;
6188 struct root_domain
*rd
;
6199 * Build an iteration mask that can exclude certain CPUs from the upwards
6202 * Asymmetric node setups can result in situations where the domain tree is of
6203 * unequal depth, make sure to skip domains that already cover the entire
6206 * In that case build_sched_domains() will have terminated the iteration early
6207 * and our sibling sd spans will be empty. Domains should always include the
6208 * cpu they're built on, so check that.
6211 static void build_group_mask(struct sched_domain
*sd
, struct sched_group
*sg
)
6213 const struct cpumask
*span
= sched_domain_span(sd
);
6214 struct sd_data
*sdd
= sd
->private;
6215 struct sched_domain
*sibling
;
6218 for_each_cpu(i
, span
) {
6219 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
6220 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
6223 cpumask_set_cpu(i
, sched_group_mask(sg
));
6228 * Return the canonical balance cpu for this group, this is the first cpu
6229 * of this group that's also in the iteration mask.
6231 int group_balance_cpu(struct sched_group
*sg
)
6233 return cpumask_first_and(sched_group_cpus(sg
), sched_group_mask(sg
));
6237 build_overlap_sched_groups(struct sched_domain
*sd
, int cpu
)
6239 struct sched_group
*first
= NULL
, *last
= NULL
, *groups
= NULL
, *sg
;
6240 const struct cpumask
*span
= sched_domain_span(sd
);
6241 struct cpumask
*covered
= sched_domains_tmpmask
;
6242 struct sd_data
*sdd
= sd
->private;
6243 struct sched_domain
*sibling
;
6246 cpumask_clear(covered
);
6248 for_each_cpu(i
, span
) {
6249 struct cpumask
*sg_span
;
6251 if (cpumask_test_cpu(i
, covered
))
6254 sibling
= *per_cpu_ptr(sdd
->sd
, i
);
6256 /* See the comment near build_group_mask(). */
6257 if (!cpumask_test_cpu(i
, sched_domain_span(sibling
)))
6260 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6261 GFP_KERNEL
, cpu_to_node(cpu
));
6266 sg_span
= sched_group_cpus(sg
);
6268 cpumask_copy(sg_span
, sched_domain_span(sibling
->child
));
6270 cpumask_set_cpu(i
, sg_span
);
6272 cpumask_or(covered
, covered
, sg_span
);
6274 sg
->sgc
= *per_cpu_ptr(sdd
->sgc
, i
);
6275 if (atomic_inc_return(&sg
->sgc
->ref
) == 1)
6276 build_group_mask(sd
, sg
);
6279 * Initialize sgc->capacity such that even if we mess up the
6280 * domains and no possible iteration will get us here, we won't
6283 sg
->sgc
->capacity
= SCHED_CAPACITY_SCALE
* cpumask_weight(sg_span
);
6286 * Make sure the first group of this domain contains the
6287 * canonical balance cpu. Otherwise the sched_domain iteration
6288 * breaks. See update_sg_lb_stats().
6290 if ((!groups
&& cpumask_test_cpu(cpu
, sg_span
)) ||
6291 group_balance_cpu(sg
) == cpu
)
6301 sd
->groups
= groups
;
6306 free_sched_groups(first
, 0);
6311 static int get_group(int cpu
, struct sd_data
*sdd
, struct sched_group
**sg
)
6313 struct sched_domain
*sd
= *per_cpu_ptr(sdd
->sd
, cpu
);
6314 struct sched_domain
*child
= sd
->child
;
6317 cpu
= cpumask_first(sched_domain_span(child
));
6320 *sg
= *per_cpu_ptr(sdd
->sg
, cpu
);
6321 (*sg
)->sgc
= *per_cpu_ptr(sdd
->sgc
, cpu
);
6322 atomic_set(&(*sg
)->sgc
->ref
, 1); /* for claim_allocations */
6329 * build_sched_groups will build a circular linked list of the groups
6330 * covered by the given span, and will set each group's ->cpumask correctly,
6331 * and ->cpu_capacity to 0.
6333 * Assumes the sched_domain tree is fully constructed
6336 build_sched_groups(struct sched_domain
*sd
, int cpu
)
6338 struct sched_group
*first
= NULL
, *last
= NULL
;
6339 struct sd_data
*sdd
= sd
->private;
6340 const struct cpumask
*span
= sched_domain_span(sd
);
6341 struct cpumask
*covered
;
6344 get_group(cpu
, sdd
, &sd
->groups
);
6345 atomic_inc(&sd
->groups
->ref
);
6347 if (cpu
!= cpumask_first(span
))
6350 lockdep_assert_held(&sched_domains_mutex
);
6351 covered
= sched_domains_tmpmask
;
6353 cpumask_clear(covered
);
6355 for_each_cpu(i
, span
) {
6356 struct sched_group
*sg
;
6359 if (cpumask_test_cpu(i
, covered
))
6362 group
= get_group(i
, sdd
, &sg
);
6363 cpumask_setall(sched_group_mask(sg
));
6365 for_each_cpu(j
, span
) {
6366 if (get_group(j
, sdd
, NULL
) != group
)
6369 cpumask_set_cpu(j
, covered
);
6370 cpumask_set_cpu(j
, sched_group_cpus(sg
));
6385 * Initialize sched groups cpu_capacity.
6387 * cpu_capacity indicates the capacity of sched group, which is used while
6388 * distributing the load between different sched groups in a sched domain.
6389 * Typically cpu_capacity for all the groups in a sched domain will be same
6390 * unless there are asymmetries in the topology. If there are asymmetries,
6391 * group having more cpu_capacity will pickup more load compared to the
6392 * group having less cpu_capacity.
6394 static void init_sched_groups_capacity(int cpu
, struct sched_domain
*sd
)
6396 struct sched_group
*sg
= sd
->groups
;
6401 sg
->group_weight
= cpumask_weight(sched_group_cpus(sg
));
6403 } while (sg
!= sd
->groups
);
6405 if (cpu
!= group_balance_cpu(sg
))
6408 update_group_capacity(sd
, cpu
);
6409 atomic_set(&sg
->sgc
->nr_busy_cpus
, sg
->group_weight
);
6413 * Initializers for schedule domains
6414 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
6417 static int default_relax_domain_level
= -1;
6418 int sched_domain_level_max
;
6420 static int __init
setup_relax_domain_level(char *str
)
6422 if (kstrtoint(str
, 0, &default_relax_domain_level
))
6423 pr_warn("Unable to set relax_domain_level\n");
6427 __setup("relax_domain_level=", setup_relax_domain_level
);
6429 static void set_domain_attribute(struct sched_domain
*sd
,
6430 struct sched_domain_attr
*attr
)
6434 if (!attr
|| attr
->relax_domain_level
< 0) {
6435 if (default_relax_domain_level
< 0)
6438 request
= default_relax_domain_level
;
6440 request
= attr
->relax_domain_level
;
6441 if (request
< sd
->level
) {
6442 /* turn off idle balance on this domain */
6443 sd
->flags
&= ~(SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6445 /* turn on idle balance on this domain */
6446 sd
->flags
|= (SD_BALANCE_WAKE
|SD_BALANCE_NEWIDLE
);
6450 static void __sdt_free(const struct cpumask
*cpu_map
);
6451 static int __sdt_alloc(const struct cpumask
*cpu_map
);
6453 static void __free_domain_allocs(struct s_data
*d
, enum s_alloc what
,
6454 const struct cpumask
*cpu_map
)
6458 if (!atomic_read(&d
->rd
->refcount
))
6459 free_rootdomain(&d
->rd
->rcu
); /* fall through */
6461 free_percpu(d
->sd
); /* fall through */
6463 __sdt_free(cpu_map
); /* fall through */
6469 static enum s_alloc
__visit_domain_allocation_hell(struct s_data
*d
,
6470 const struct cpumask
*cpu_map
)
6472 memset(d
, 0, sizeof(*d
));
6474 if (__sdt_alloc(cpu_map
))
6475 return sa_sd_storage
;
6476 d
->sd
= alloc_percpu(struct sched_domain
*);
6478 return sa_sd_storage
;
6479 d
->rd
= alloc_rootdomain();
6482 return sa_rootdomain
;
6486 * NULL the sd_data elements we've used to build the sched_domain and
6487 * sched_group structure so that the subsequent __free_domain_allocs()
6488 * will not free the data we're using.
6490 static void claim_allocations(int cpu
, struct sched_domain
*sd
)
6492 struct sd_data
*sdd
= sd
->private;
6494 WARN_ON_ONCE(*per_cpu_ptr(sdd
->sd
, cpu
) != sd
);
6495 *per_cpu_ptr(sdd
->sd
, cpu
) = NULL
;
6497 if (atomic_read(&(*per_cpu_ptr(sdd
->sg
, cpu
))->ref
))
6498 *per_cpu_ptr(sdd
->sg
, cpu
) = NULL
;
6500 if (atomic_read(&(*per_cpu_ptr(sdd
->sgc
, cpu
))->ref
))
6501 *per_cpu_ptr(sdd
->sgc
, cpu
) = NULL
;
6505 static int sched_domains_numa_levels
;
6506 enum numa_topology_type sched_numa_topology_type
;
6507 static int *sched_domains_numa_distance
;
6508 int sched_max_numa_distance
;
6509 static struct cpumask
***sched_domains_numa_masks
;
6510 static int sched_domains_curr_level
;
6514 * SD_flags allowed in topology descriptions.
6516 * SD_SHARE_CPUCAPACITY - describes SMT topologies
6517 * SD_SHARE_PKG_RESOURCES - describes shared caches
6518 * SD_NUMA - describes NUMA topologies
6519 * SD_SHARE_POWERDOMAIN - describes shared power domain
6522 * SD_ASYM_PACKING - describes SMT quirks
6524 #define TOPOLOGY_SD_FLAGS \
6525 (SD_SHARE_CPUCAPACITY | \
6526 SD_SHARE_PKG_RESOURCES | \
6529 SD_SHARE_POWERDOMAIN)
6531 static struct sched_domain
*
6532 sd_init(struct sched_domain_topology_level
*tl
, int cpu
)
6534 struct sched_domain
*sd
= *per_cpu_ptr(tl
->data
.sd
, cpu
);
6535 int sd_weight
, sd_flags
= 0;
6539 * Ugly hack to pass state to sd_numa_mask()...
6541 sched_domains_curr_level
= tl
->numa_level
;
6544 sd_weight
= cpumask_weight(tl
->mask(cpu
));
6547 sd_flags
= (*tl
->sd_flags
)();
6548 if (WARN_ONCE(sd_flags
& ~TOPOLOGY_SD_FLAGS
,
6549 "wrong sd_flags in topology description\n"))
6550 sd_flags
&= ~TOPOLOGY_SD_FLAGS
;
6552 *sd
= (struct sched_domain
){
6553 .min_interval
= sd_weight
,
6554 .max_interval
= 2*sd_weight
,
6556 .imbalance_pct
= 125,
6558 .cache_nice_tries
= 0,
6565 .flags
= 1*SD_LOAD_BALANCE
6566 | 1*SD_BALANCE_NEWIDLE
6571 | 0*SD_SHARE_CPUCAPACITY
6572 | 0*SD_SHARE_PKG_RESOURCES
6574 | 0*SD_PREFER_SIBLING
6579 .last_balance
= jiffies
,
6580 .balance_interval
= sd_weight
,
6582 .max_newidle_lb_cost
= 0,
6583 .next_decay_max_lb_cost
= jiffies
,
6584 #ifdef CONFIG_SCHED_DEBUG
6590 * Convert topological properties into behaviour.
6593 if (sd
->flags
& SD_SHARE_CPUCAPACITY
) {
6594 sd
->flags
|= SD_PREFER_SIBLING
;
6595 sd
->imbalance_pct
= 110;
6596 sd
->smt_gain
= 1178; /* ~15% */
6598 } else if (sd
->flags
& SD_SHARE_PKG_RESOURCES
) {
6599 sd
->imbalance_pct
= 117;
6600 sd
->cache_nice_tries
= 1;
6604 } else if (sd
->flags
& SD_NUMA
) {
6605 sd
->cache_nice_tries
= 2;
6609 sd
->flags
|= SD_SERIALIZE
;
6610 if (sched_domains_numa_distance
[tl
->numa_level
] > RECLAIM_DISTANCE
) {
6611 sd
->flags
&= ~(SD_BALANCE_EXEC
|
6618 sd
->flags
|= SD_PREFER_SIBLING
;
6619 sd
->cache_nice_tries
= 1;
6624 sd
->private = &tl
->data
;
6630 * Topology list, bottom-up.
6632 static struct sched_domain_topology_level default_topology
[] = {
6633 #ifdef CONFIG_SCHED_SMT
6634 { cpu_smt_mask
, cpu_smt_flags
, SD_INIT_NAME(SMT
) },
6636 #ifdef CONFIG_SCHED_MC
6637 { cpu_coregroup_mask
, cpu_core_flags
, SD_INIT_NAME(MC
) },
6639 { cpu_cpu_mask
, SD_INIT_NAME(DIE
) },
6643 static struct sched_domain_topology_level
*sched_domain_topology
=
6646 #define for_each_sd_topology(tl) \
6647 for (tl = sched_domain_topology; tl->mask; tl++)
6649 void set_sched_topology(struct sched_domain_topology_level
*tl
)
6651 sched_domain_topology
= tl
;
6656 static const struct cpumask
*sd_numa_mask(int cpu
)
6658 return sched_domains_numa_masks
[sched_domains_curr_level
][cpu_to_node(cpu
)];
6661 static void sched_numa_warn(const char *str
)
6663 static int done
= false;
6671 printk(KERN_WARNING
"ERROR: %s\n\n", str
);
6673 for (i
= 0; i
< nr_node_ids
; i
++) {
6674 printk(KERN_WARNING
" ");
6675 for (j
= 0; j
< nr_node_ids
; j
++)
6676 printk(KERN_CONT
"%02d ", node_distance(i
,j
));
6677 printk(KERN_CONT
"\n");
6679 printk(KERN_WARNING
"\n");
6682 bool find_numa_distance(int distance
)
6686 if (distance
== node_distance(0, 0))
6689 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6690 if (sched_domains_numa_distance
[i
] == distance
)
6698 * A system can have three types of NUMA topology:
6699 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
6700 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
6701 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
6703 * The difference between a glueless mesh topology and a backplane
6704 * topology lies in whether communication between not directly
6705 * connected nodes goes through intermediary nodes (where programs
6706 * could run), or through backplane controllers. This affects
6707 * placement of programs.
6709 * The type of topology can be discerned with the following tests:
6710 * - If the maximum distance between any nodes is 1 hop, the system
6711 * is directly connected.
6712 * - If for two nodes A and B, located N > 1 hops away from each other,
6713 * there is an intermediary node C, which is < N hops away from both
6714 * nodes A and B, the system is a glueless mesh.
6716 static void init_numa_topology_type(void)
6720 n
= sched_max_numa_distance
;
6722 if (sched_domains_numa_levels
<= 1) {
6723 sched_numa_topology_type
= NUMA_DIRECT
;
6727 for_each_online_node(a
) {
6728 for_each_online_node(b
) {
6729 /* Find two nodes furthest removed from each other. */
6730 if (node_distance(a
, b
) < n
)
6733 /* Is there an intermediary node between a and b? */
6734 for_each_online_node(c
) {
6735 if (node_distance(a
, c
) < n
&&
6736 node_distance(b
, c
) < n
) {
6737 sched_numa_topology_type
=
6743 sched_numa_topology_type
= NUMA_BACKPLANE
;
6749 static void sched_init_numa(void)
6751 int next_distance
, curr_distance
= node_distance(0, 0);
6752 struct sched_domain_topology_level
*tl
;
6756 sched_domains_numa_distance
= kzalloc(sizeof(int) * nr_node_ids
, GFP_KERNEL
);
6757 if (!sched_domains_numa_distance
)
6761 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
6762 * unique distances in the node_distance() table.
6764 * Assumes node_distance(0,j) includes all distances in
6765 * node_distance(i,j) in order to avoid cubic time.
6767 next_distance
= curr_distance
;
6768 for (i
= 0; i
< nr_node_ids
; i
++) {
6769 for (j
= 0; j
< nr_node_ids
; j
++) {
6770 for (k
= 0; k
< nr_node_ids
; k
++) {
6771 int distance
= node_distance(i
, k
);
6773 if (distance
> curr_distance
&&
6774 (distance
< next_distance
||
6775 next_distance
== curr_distance
))
6776 next_distance
= distance
;
6779 * While not a strong assumption it would be nice to know
6780 * about cases where if node A is connected to B, B is not
6781 * equally connected to A.
6783 if (sched_debug() && node_distance(k
, i
) != distance
)
6784 sched_numa_warn("Node-distance not symmetric");
6786 if (sched_debug() && i
&& !find_numa_distance(distance
))
6787 sched_numa_warn("Node-0 not representative");
6789 if (next_distance
!= curr_distance
) {
6790 sched_domains_numa_distance
[level
++] = next_distance
;
6791 sched_domains_numa_levels
= level
;
6792 curr_distance
= next_distance
;
6797 * In case of sched_debug() we verify the above assumption.
6807 * 'level' contains the number of unique distances, excluding the
6808 * identity distance node_distance(i,i).
6810 * The sched_domains_numa_distance[] array includes the actual distance
6815 * Here, we should temporarily reset sched_domains_numa_levels to 0.
6816 * If it fails to allocate memory for array sched_domains_numa_masks[][],
6817 * the array will contain less then 'level' members. This could be
6818 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
6819 * in other functions.
6821 * We reset it to 'level' at the end of this function.
6823 sched_domains_numa_levels
= 0;
6825 sched_domains_numa_masks
= kzalloc(sizeof(void *) * level
, GFP_KERNEL
);
6826 if (!sched_domains_numa_masks
)
6830 * Now for each level, construct a mask per node which contains all
6831 * cpus of nodes that are that many hops away from us.
6833 for (i
= 0; i
< level
; i
++) {
6834 sched_domains_numa_masks
[i
] =
6835 kzalloc(nr_node_ids
* sizeof(void *), GFP_KERNEL
);
6836 if (!sched_domains_numa_masks
[i
])
6839 for (j
= 0; j
< nr_node_ids
; j
++) {
6840 struct cpumask
*mask
= kzalloc(cpumask_size(), GFP_KERNEL
);
6844 sched_domains_numa_masks
[i
][j
] = mask
;
6847 if (node_distance(j
, k
) > sched_domains_numa_distance
[i
])
6850 cpumask_or(mask
, mask
, cpumask_of_node(k
));
6855 /* Compute default topology size */
6856 for (i
= 0; sched_domain_topology
[i
].mask
; i
++);
6858 tl
= kzalloc((i
+ level
+ 1) *
6859 sizeof(struct sched_domain_topology_level
), GFP_KERNEL
);
6864 * Copy the default topology bits..
6866 for (i
= 0; sched_domain_topology
[i
].mask
; i
++)
6867 tl
[i
] = sched_domain_topology
[i
];
6870 * .. and append 'j' levels of NUMA goodness.
6872 for (j
= 0; j
< level
; i
++, j
++) {
6873 tl
[i
] = (struct sched_domain_topology_level
){
6874 .mask
= sd_numa_mask
,
6875 .sd_flags
= cpu_numa_flags
,
6876 .flags
= SDTL_OVERLAP
,
6882 sched_domain_topology
= tl
;
6884 sched_domains_numa_levels
= level
;
6885 sched_max_numa_distance
= sched_domains_numa_distance
[level
- 1];
6887 init_numa_topology_type();
6890 static void sched_domains_numa_masks_set(int cpu
)
6893 int node
= cpu_to_node(cpu
);
6895 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6896 for (j
= 0; j
< nr_node_ids
; j
++) {
6897 if (node_distance(j
, node
) <= sched_domains_numa_distance
[i
])
6898 cpumask_set_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6903 static void sched_domains_numa_masks_clear(int cpu
)
6906 for (i
= 0; i
< sched_domains_numa_levels
; i
++) {
6907 for (j
= 0; j
< nr_node_ids
; j
++)
6908 cpumask_clear_cpu(cpu
, sched_domains_numa_masks
[i
][j
]);
6913 * Update sched_domains_numa_masks[level][node] array when new cpus
6916 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6917 unsigned long action
,
6920 int cpu
= (long)hcpu
;
6922 switch (action
& ~CPU_TASKS_FROZEN
) {
6924 sched_domains_numa_masks_set(cpu
);
6928 sched_domains_numa_masks_clear(cpu
);
6938 static inline void sched_init_numa(void)
6942 static int sched_domains_numa_masks_update(struct notifier_block
*nfb
,
6943 unsigned long action
,
6948 #endif /* CONFIG_NUMA */
6950 static int __sdt_alloc(const struct cpumask
*cpu_map
)
6952 struct sched_domain_topology_level
*tl
;
6955 for_each_sd_topology(tl
) {
6956 struct sd_data
*sdd
= &tl
->data
;
6958 sdd
->sd
= alloc_percpu(struct sched_domain
*);
6962 sdd
->sg
= alloc_percpu(struct sched_group
*);
6966 sdd
->sgc
= alloc_percpu(struct sched_group_capacity
*);
6970 for_each_cpu(j
, cpu_map
) {
6971 struct sched_domain
*sd
;
6972 struct sched_group
*sg
;
6973 struct sched_group_capacity
*sgc
;
6975 sd
= kzalloc_node(sizeof(struct sched_domain
) + cpumask_size(),
6976 GFP_KERNEL
, cpu_to_node(j
));
6980 *per_cpu_ptr(sdd
->sd
, j
) = sd
;
6982 sg
= kzalloc_node(sizeof(struct sched_group
) + cpumask_size(),
6983 GFP_KERNEL
, cpu_to_node(j
));
6989 *per_cpu_ptr(sdd
->sg
, j
) = sg
;
6991 sgc
= kzalloc_node(sizeof(struct sched_group_capacity
) + cpumask_size(),
6992 GFP_KERNEL
, cpu_to_node(j
));
6996 *per_cpu_ptr(sdd
->sgc
, j
) = sgc
;
7003 static void __sdt_free(const struct cpumask
*cpu_map
)
7005 struct sched_domain_topology_level
*tl
;
7008 for_each_sd_topology(tl
) {
7009 struct sd_data
*sdd
= &tl
->data
;
7011 for_each_cpu(j
, cpu_map
) {
7012 struct sched_domain
*sd
;
7015 sd
= *per_cpu_ptr(sdd
->sd
, j
);
7016 if (sd
&& (sd
->flags
& SD_OVERLAP
))
7017 free_sched_groups(sd
->groups
, 0);
7018 kfree(*per_cpu_ptr(sdd
->sd
, j
));
7022 kfree(*per_cpu_ptr(sdd
->sg
, j
));
7024 kfree(*per_cpu_ptr(sdd
->sgc
, j
));
7026 free_percpu(sdd
->sd
);
7028 free_percpu(sdd
->sg
);
7030 free_percpu(sdd
->sgc
);
7035 struct sched_domain
*build_sched_domain(struct sched_domain_topology_level
*tl
,
7036 const struct cpumask
*cpu_map
, struct sched_domain_attr
*attr
,
7037 struct sched_domain
*child
, int cpu
)
7039 struct sched_domain
*sd
= sd_init(tl
, cpu
);
7043 cpumask_and(sched_domain_span(sd
), cpu_map
, tl
->mask(cpu
));
7045 sd
->level
= child
->level
+ 1;
7046 sched_domain_level_max
= max(sched_domain_level_max
, sd
->level
);
7050 if (!cpumask_subset(sched_domain_span(child
),
7051 sched_domain_span(sd
))) {
7052 pr_err("BUG: arch topology borken\n");
7053 #ifdef CONFIG_SCHED_DEBUG
7054 pr_err(" the %s domain not a subset of the %s domain\n",
7055 child
->name
, sd
->name
);
7057 /* Fixup, ensure @sd has at least @child cpus. */
7058 cpumask_or(sched_domain_span(sd
),
7059 sched_domain_span(sd
),
7060 sched_domain_span(child
));
7064 set_domain_attribute(sd
, attr
);
7070 * Build sched domains for a given set of cpus and attach the sched domains
7071 * to the individual cpus
7073 static int build_sched_domains(const struct cpumask
*cpu_map
,
7074 struct sched_domain_attr
*attr
)
7076 enum s_alloc alloc_state
;
7077 struct sched_domain
*sd
;
7079 int i
, ret
= -ENOMEM
;
7081 alloc_state
= __visit_domain_allocation_hell(&d
, cpu_map
);
7082 if (alloc_state
!= sa_rootdomain
)
7085 /* Set up domains for cpus specified by the cpu_map. */
7086 for_each_cpu(i
, cpu_map
) {
7087 struct sched_domain_topology_level
*tl
;
7090 for_each_sd_topology(tl
) {
7091 sd
= build_sched_domain(tl
, cpu_map
, attr
, sd
, i
);
7092 if (tl
== sched_domain_topology
)
7093 *per_cpu_ptr(d
.sd
, i
) = sd
;
7094 if (tl
->flags
& SDTL_OVERLAP
|| sched_feat(FORCE_SD_OVERLAP
))
7095 sd
->flags
|= SD_OVERLAP
;
7096 if (cpumask_equal(cpu_map
, sched_domain_span(sd
)))
7101 /* Build the groups for the domains */
7102 for_each_cpu(i
, cpu_map
) {
7103 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
7104 sd
->span_weight
= cpumask_weight(sched_domain_span(sd
));
7105 if (sd
->flags
& SD_OVERLAP
) {
7106 if (build_overlap_sched_groups(sd
, i
))
7109 if (build_sched_groups(sd
, i
))
7115 /* Calculate CPU capacity for physical packages and nodes */
7116 for (i
= nr_cpumask_bits
-1; i
>= 0; i
--) {
7117 if (!cpumask_test_cpu(i
, cpu_map
))
7120 for (sd
= *per_cpu_ptr(d
.sd
, i
); sd
; sd
= sd
->parent
) {
7121 claim_allocations(i
, sd
);
7122 init_sched_groups_capacity(i
, sd
);
7126 /* Attach the domains */
7128 for_each_cpu(i
, cpu_map
) {
7129 sd
= *per_cpu_ptr(d
.sd
, i
);
7130 cpu_attach_domain(sd
, d
.rd
, i
);
7136 __free_domain_allocs(&d
, alloc_state
, cpu_map
);
7140 static cpumask_var_t
*doms_cur
; /* current sched domains */
7141 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
7142 static struct sched_domain_attr
*dattr_cur
;
7143 /* attribues of custom domains in 'doms_cur' */
7146 * Special case: If a kmalloc of a doms_cur partition (array of
7147 * cpumask) fails, then fallback to a single sched domain,
7148 * as determined by the single cpumask fallback_doms.
7150 static cpumask_var_t fallback_doms
;
7153 * arch_update_cpu_topology lets virtualized architectures update the
7154 * cpu core maps. It is supposed to return 1 if the topology changed
7155 * or 0 if it stayed the same.
7157 int __weak
arch_update_cpu_topology(void)
7162 cpumask_var_t
*alloc_sched_domains(unsigned int ndoms
)
7165 cpumask_var_t
*doms
;
7167 doms
= kmalloc(sizeof(*doms
) * ndoms
, GFP_KERNEL
);
7170 for (i
= 0; i
< ndoms
; i
++) {
7171 if (!alloc_cpumask_var(&doms
[i
], GFP_KERNEL
)) {
7172 free_sched_domains(doms
, i
);
7179 void free_sched_domains(cpumask_var_t doms
[], unsigned int ndoms
)
7182 for (i
= 0; i
< ndoms
; i
++)
7183 free_cpumask_var(doms
[i
]);
7188 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
7189 * For now this just excludes isolated cpus, but could be used to
7190 * exclude other special cases in the future.
7192 static int init_sched_domains(const struct cpumask
*cpu_map
)
7196 arch_update_cpu_topology();
7198 doms_cur
= alloc_sched_domains(ndoms_cur
);
7200 doms_cur
= &fallback_doms
;
7201 cpumask_andnot(doms_cur
[0], cpu_map
, cpu_isolated_map
);
7202 err
= build_sched_domains(doms_cur
[0], NULL
);
7203 register_sched_domain_sysctl();
7209 * Detach sched domains from a group of cpus specified in cpu_map
7210 * These cpus will now be attached to the NULL domain
7212 static void detach_destroy_domains(const struct cpumask
*cpu_map
)
7217 for_each_cpu(i
, cpu_map
)
7218 cpu_attach_domain(NULL
, &def_root_domain
, i
);
7222 /* handle null as "default" */
7223 static int dattrs_equal(struct sched_domain_attr
*cur
, int idx_cur
,
7224 struct sched_domain_attr
*new, int idx_new
)
7226 struct sched_domain_attr tmp
;
7233 return !memcmp(cur
? (cur
+ idx_cur
) : &tmp
,
7234 new ? (new + idx_new
) : &tmp
,
7235 sizeof(struct sched_domain_attr
));
7239 * Partition sched domains as specified by the 'ndoms_new'
7240 * cpumasks in the array doms_new[] of cpumasks. This compares
7241 * doms_new[] to the current sched domain partitioning, doms_cur[].
7242 * It destroys each deleted domain and builds each new domain.
7244 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
7245 * The masks don't intersect (don't overlap.) We should setup one
7246 * sched domain for each mask. CPUs not in any of the cpumasks will
7247 * not be load balanced. If the same cpumask appears both in the
7248 * current 'doms_cur' domains and in the new 'doms_new', we can leave
7251 * The passed in 'doms_new' should be allocated using
7252 * alloc_sched_domains. This routine takes ownership of it and will
7253 * free_sched_domains it when done with it. If the caller failed the
7254 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
7255 * and partition_sched_domains() will fallback to the single partition
7256 * 'fallback_doms', it also forces the domains to be rebuilt.
7258 * If doms_new == NULL it will be replaced with cpu_online_mask.
7259 * ndoms_new == 0 is a special case for destroying existing domains,
7260 * and it will not create the default domain.
7262 * Call with hotplug lock held
7264 void partition_sched_domains(int ndoms_new
, cpumask_var_t doms_new
[],
7265 struct sched_domain_attr
*dattr_new
)
7270 mutex_lock(&sched_domains_mutex
);
7272 /* always unregister in case we don't destroy any domains */
7273 unregister_sched_domain_sysctl();
7275 /* Let architecture update cpu core mappings. */
7276 new_topology
= arch_update_cpu_topology();
7278 n
= doms_new
? ndoms_new
: 0;
7280 /* Destroy deleted domains */
7281 for (i
= 0; i
< ndoms_cur
; i
++) {
7282 for (j
= 0; j
< n
&& !new_topology
; j
++) {
7283 if (cpumask_equal(doms_cur
[i
], doms_new
[j
])
7284 && dattrs_equal(dattr_cur
, i
, dattr_new
, j
))
7287 /* no match - a current sched domain not in new doms_new[] */
7288 detach_destroy_domains(doms_cur
[i
]);
7294 if (doms_new
== NULL
) {
7296 doms_new
= &fallback_doms
;
7297 cpumask_andnot(doms_new
[0], cpu_active_mask
, cpu_isolated_map
);
7298 WARN_ON_ONCE(dattr_new
);
7301 /* Build new domains */
7302 for (i
= 0; i
< ndoms_new
; i
++) {
7303 for (j
= 0; j
< n
&& !new_topology
; j
++) {
7304 if (cpumask_equal(doms_new
[i
], doms_cur
[j
])
7305 && dattrs_equal(dattr_new
, i
, dattr_cur
, j
))
7308 /* no match - add a new doms_new */
7309 build_sched_domains(doms_new
[i
], dattr_new
? dattr_new
+ i
: NULL
);
7314 /* Remember the new sched domains */
7315 if (doms_cur
!= &fallback_doms
)
7316 free_sched_domains(doms_cur
, ndoms_cur
);
7317 kfree(dattr_cur
); /* kfree(NULL) is safe */
7318 doms_cur
= doms_new
;
7319 dattr_cur
= dattr_new
;
7320 ndoms_cur
= ndoms_new
;
7322 register_sched_domain_sysctl();
7324 mutex_unlock(&sched_domains_mutex
);
7327 static int num_cpus_frozen
; /* used to mark begin/end of suspend/resume */
7330 * Update cpusets according to cpu_active mask. If cpusets are
7331 * disabled, cpuset_update_active_cpus() becomes a simple wrapper
7332 * around partition_sched_domains().
7334 * If we come here as part of a suspend/resume, don't touch cpusets because we
7335 * want to restore it back to its original state upon resume anyway.
7337 static int cpuset_cpu_active(struct notifier_block
*nfb
, unsigned long action
,
7341 case CPU_ONLINE_FROZEN
:
7342 case CPU_DOWN_FAILED_FROZEN
:
7345 * num_cpus_frozen tracks how many CPUs are involved in suspend
7346 * resume sequence. As long as this is not the last online
7347 * operation in the resume sequence, just build a single sched
7348 * domain, ignoring cpusets.
7351 if (likely(num_cpus_frozen
)) {
7352 partition_sched_domains(1, NULL
, NULL
);
7357 * This is the last CPU online operation. So fall through and
7358 * restore the original sched domains by considering the
7359 * cpuset configurations.
7363 cpuset_update_active_cpus(true);
7371 static int cpuset_cpu_inactive(struct notifier_block
*nfb
, unsigned long action
,
7374 unsigned long flags
;
7375 long cpu
= (long)hcpu
;
7381 case CPU_DOWN_PREPARE
:
7382 rcu_read_lock_sched();
7383 dl_b
= dl_bw_of(cpu
);
7385 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
7386 cpus
= dl_bw_cpus(cpu
);
7387 overflow
= __dl_overflow(dl_b
, cpus
, 0, 0);
7388 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
7390 rcu_read_unlock_sched();
7393 return notifier_from_errno(-EBUSY
);
7394 cpuset_update_active_cpus(false);
7396 case CPU_DOWN_PREPARE_FROZEN
:
7398 partition_sched_domains(1, NULL
, NULL
);
7406 void __init
sched_init_smp(void)
7408 cpumask_var_t non_isolated_cpus
;
7410 alloc_cpumask_var(&non_isolated_cpus
, GFP_KERNEL
);
7411 alloc_cpumask_var(&fallback_doms
, GFP_KERNEL
);
7416 * There's no userspace yet to cause hotplug operations; hence all the
7417 * cpu masks are stable and all blatant races in the below code cannot
7420 mutex_lock(&sched_domains_mutex
);
7421 init_sched_domains(cpu_active_mask
);
7422 cpumask_andnot(non_isolated_cpus
, cpu_possible_mask
, cpu_isolated_map
);
7423 if (cpumask_empty(non_isolated_cpus
))
7424 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus
);
7425 mutex_unlock(&sched_domains_mutex
);
7427 hotcpu_notifier(sched_domains_numa_masks_update
, CPU_PRI_SCHED_ACTIVE
);
7428 hotcpu_notifier(cpuset_cpu_active
, CPU_PRI_CPUSET_ACTIVE
);
7429 hotcpu_notifier(cpuset_cpu_inactive
, CPU_PRI_CPUSET_INACTIVE
);
7433 /* Move init over to a non-isolated CPU */
7434 if (set_cpus_allowed_ptr(current
, non_isolated_cpus
) < 0)
7436 sched_init_granularity();
7437 free_cpumask_var(non_isolated_cpus
);
7439 init_sched_rt_class();
7440 init_sched_dl_class();
7443 void __init
sched_init_smp(void)
7445 sched_init_granularity();
7447 #endif /* CONFIG_SMP */
7449 int in_sched_functions(unsigned long addr
)
7451 return in_lock_functions(addr
) ||
7452 (addr
>= (unsigned long)__sched_text_start
7453 && addr
< (unsigned long)__sched_text_end
);
7456 #ifdef CONFIG_CGROUP_SCHED
7458 * Default task group.
7459 * Every task in system belongs to this group at bootup.
7461 struct task_group root_task_group
;
7462 LIST_HEAD(task_groups
);
7464 /* Cacheline aligned slab cache for task_group */
7465 static struct kmem_cache
*task_group_cache __read_mostly
;
7468 DECLARE_PER_CPU(cpumask_var_t
, load_balance_mask
);
7470 void __init
sched_init(void)
7473 unsigned long alloc_size
= 0, ptr
;
7475 #ifdef CONFIG_FAIR_GROUP_SCHED
7476 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7478 #ifdef CONFIG_RT_GROUP_SCHED
7479 alloc_size
+= 2 * nr_cpu_ids
* sizeof(void **);
7482 ptr
= (unsigned long)kzalloc(alloc_size
, GFP_NOWAIT
);
7484 #ifdef CONFIG_FAIR_GROUP_SCHED
7485 root_task_group
.se
= (struct sched_entity
**)ptr
;
7486 ptr
+= nr_cpu_ids
* sizeof(void **);
7488 root_task_group
.cfs_rq
= (struct cfs_rq
**)ptr
;
7489 ptr
+= nr_cpu_ids
* sizeof(void **);
7491 #endif /* CONFIG_FAIR_GROUP_SCHED */
7492 #ifdef CONFIG_RT_GROUP_SCHED
7493 root_task_group
.rt_se
= (struct sched_rt_entity
**)ptr
;
7494 ptr
+= nr_cpu_ids
* sizeof(void **);
7496 root_task_group
.rt_rq
= (struct rt_rq
**)ptr
;
7497 ptr
+= nr_cpu_ids
* sizeof(void **);
7499 #endif /* CONFIG_RT_GROUP_SCHED */
7501 #ifdef CONFIG_CPUMASK_OFFSTACK
7502 for_each_possible_cpu(i
) {
7503 per_cpu(load_balance_mask
, i
) = (cpumask_var_t
)kzalloc_node(
7504 cpumask_size(), GFP_KERNEL
, cpu_to_node(i
));
7506 #endif /* CONFIG_CPUMASK_OFFSTACK */
7508 init_rt_bandwidth(&def_rt_bandwidth
,
7509 global_rt_period(), global_rt_runtime());
7510 init_dl_bandwidth(&def_dl_bandwidth
,
7511 global_rt_period(), global_rt_runtime());
7514 init_defrootdomain();
7517 #ifdef CONFIG_RT_GROUP_SCHED
7518 init_rt_bandwidth(&root_task_group
.rt_bandwidth
,
7519 global_rt_period(), global_rt_runtime());
7520 #endif /* CONFIG_RT_GROUP_SCHED */
7522 #ifdef CONFIG_CGROUP_SCHED
7523 task_group_cache
= KMEM_CACHE(task_group
, 0);
7525 list_add(&root_task_group
.list
, &task_groups
);
7526 INIT_LIST_HEAD(&root_task_group
.children
);
7527 INIT_LIST_HEAD(&root_task_group
.siblings
);
7528 autogroup_init(&init_task
);
7529 #endif /* CONFIG_CGROUP_SCHED */
7531 for_each_possible_cpu(i
) {
7535 raw_spin_lock_init(&rq
->lock
);
7537 rq
->calc_load_active
= 0;
7538 rq
->calc_load_update
= jiffies
+ LOAD_FREQ
;
7539 init_cfs_rq(&rq
->cfs
);
7540 init_rt_rq(&rq
->rt
);
7541 init_dl_rq(&rq
->dl
);
7542 #ifdef CONFIG_FAIR_GROUP_SCHED
7543 root_task_group
.shares
= ROOT_TASK_GROUP_LOAD
;
7544 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
7546 * How much cpu bandwidth does root_task_group get?
7548 * In case of task-groups formed thr' the cgroup filesystem, it
7549 * gets 100% of the cpu resources in the system. This overall
7550 * system cpu resource is divided among the tasks of
7551 * root_task_group and its child task-groups in a fair manner,
7552 * based on each entity's (task or task-group's) weight
7553 * (se->load.weight).
7555 * In other words, if root_task_group has 10 tasks of weight
7556 * 1024) and two child groups A0 and A1 (of weight 1024 each),
7557 * then A0's share of the cpu resource is:
7559 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
7561 * We achieve this by letting root_task_group's tasks sit
7562 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
7564 init_cfs_bandwidth(&root_task_group
.cfs_bandwidth
);
7565 init_tg_cfs_entry(&root_task_group
, &rq
->cfs
, NULL
, i
, NULL
);
7566 #endif /* CONFIG_FAIR_GROUP_SCHED */
7568 rq
->rt
.rt_runtime
= def_rt_bandwidth
.rt_runtime
;
7569 #ifdef CONFIG_RT_GROUP_SCHED
7570 init_tg_rt_entry(&root_task_group
, &rq
->rt
, NULL
, i
, NULL
);
7573 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7574 rq
->cpu_load
[j
] = 0;
7576 rq
->last_load_update_tick
= jiffies
;
7581 rq
->cpu_capacity
= rq
->cpu_capacity_orig
= SCHED_CAPACITY_SCALE
;
7582 rq
->balance_callback
= NULL
;
7583 rq
->active_balance
= 0;
7584 rq
->next_balance
= jiffies
;
7589 rq
->avg_idle
= 2*sysctl_sched_migration_cost
;
7590 rq
->max_idle_balance_cost
= sysctl_sched_migration_cost
;
7592 INIT_LIST_HEAD(&rq
->cfs_tasks
);
7594 rq_attach_root(rq
, &def_root_domain
);
7595 #ifdef CONFIG_NO_HZ_COMMON
7598 #ifdef CONFIG_NO_HZ_FULL
7599 rq
->last_sched_tick
= 0;
7603 atomic_set(&rq
->nr_iowait
, 0);
7606 set_load_weight(&init_task
);
7608 #ifdef CONFIG_PREEMPT_NOTIFIERS
7609 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7613 * The boot idle thread does lazy MMU switching as well:
7615 atomic_inc(&init_mm
.mm_count
);
7616 enter_lazy_tlb(&init_mm
, current
);
7619 * During early bootup we pretend to be a normal task:
7621 current
->sched_class
= &fair_sched_class
;
7624 * Make us the idle thread. Technically, schedule() should not be
7625 * called from this thread, however somewhere below it might be,
7626 * but because we are the idle thread, we just pick up running again
7627 * when this runqueue becomes "idle".
7629 init_idle(current
, smp_processor_id());
7631 calc_load_update
= jiffies
+ LOAD_FREQ
;
7634 zalloc_cpumask_var(&sched_domains_tmpmask
, GFP_NOWAIT
);
7635 /* May be allocated at isolcpus cmdline parse time */
7636 if (cpu_isolated_map
== NULL
)
7637 zalloc_cpumask_var(&cpu_isolated_map
, GFP_NOWAIT
);
7638 idle_thread_set_boot_cpu();
7639 set_cpu_rq_start_time();
7641 init_sched_fair_class();
7643 scheduler_running
= 1;
7646 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
7647 static inline int preempt_count_equals(int preempt_offset
)
7649 int nested
= preempt_count() + rcu_preempt_depth();
7651 return (nested
== preempt_offset
);
7654 void __might_sleep(const char *file
, int line
, int preempt_offset
)
7657 * Blocking primitives will set (and therefore destroy) current->state,
7658 * since we will exit with TASK_RUNNING make sure we enter with it,
7659 * otherwise we will destroy state.
7661 WARN_ONCE(current
->state
!= TASK_RUNNING
&& current
->task_state_change
,
7662 "do not call blocking ops when !TASK_RUNNING; "
7663 "state=%lx set at [<%p>] %pS\n",
7665 (void *)current
->task_state_change
,
7666 (void *)current
->task_state_change
);
7668 ___might_sleep(file
, line
, preempt_offset
);
7670 EXPORT_SYMBOL(__might_sleep
);
7672 void ___might_sleep(const char *file
, int line
, int preempt_offset
)
7674 static unsigned long prev_jiffy
; /* ratelimiting */
7676 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
7677 if ((preempt_count_equals(preempt_offset
) && !irqs_disabled() &&
7678 !is_idle_task(current
)) ||
7679 system_state
!= SYSTEM_RUNNING
|| oops_in_progress
)
7681 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7683 prev_jiffy
= jiffies
;
7686 "BUG: sleeping function called from invalid context at %s:%d\n",
7689 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
7690 in_atomic(), irqs_disabled(),
7691 current
->pid
, current
->comm
);
7693 if (task_stack_end_corrupted(current
))
7694 printk(KERN_EMERG
"Thread overran stack, or stack corrupted\n");
7696 debug_show_held_locks(current
);
7697 if (irqs_disabled())
7698 print_irqtrace_events(current
);
7699 #ifdef CONFIG_DEBUG_PREEMPT
7700 if (!preempt_count_equals(preempt_offset
)) {
7701 pr_err("Preemption disabled at:");
7702 print_ip_sym(current
->preempt_disable_ip
);
7708 EXPORT_SYMBOL(___might_sleep
);
7711 #ifdef CONFIG_MAGIC_SYSRQ
7712 void normalize_rt_tasks(void)
7714 struct task_struct
*g
, *p
;
7715 struct sched_attr attr
= {
7716 .sched_policy
= SCHED_NORMAL
,
7719 read_lock(&tasklist_lock
);
7720 for_each_process_thread(g
, p
) {
7722 * Only normalize user tasks:
7724 if (p
->flags
& PF_KTHREAD
)
7727 p
->se
.exec_start
= 0;
7728 #ifdef CONFIG_SCHEDSTATS
7729 p
->se
.statistics
.wait_start
= 0;
7730 p
->se
.statistics
.sleep_start
= 0;
7731 p
->se
.statistics
.block_start
= 0;
7734 if (!dl_task(p
) && !rt_task(p
)) {
7736 * Renice negative nice level userspace
7739 if (task_nice(p
) < 0)
7740 set_user_nice(p
, 0);
7744 __sched_setscheduler(p
, &attr
, false, false);
7746 read_unlock(&tasklist_lock
);
7749 #endif /* CONFIG_MAGIC_SYSRQ */
7751 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
7753 * These functions are only useful for the IA64 MCA handling, or kdb.
7755 * They can only be called when the whole system has been
7756 * stopped - every CPU needs to be quiescent, and no scheduling
7757 * activity can take place. Using them for anything else would
7758 * be a serious bug, and as a result, they aren't even visible
7759 * under any other configuration.
7763 * curr_task - return the current task for a given cpu.
7764 * @cpu: the processor in question.
7766 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7768 * Return: The current task for @cpu.
7770 struct task_struct
*curr_task(int cpu
)
7772 return cpu_curr(cpu
);
7775 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
7779 * set_curr_task - set the current task for a given cpu.
7780 * @cpu: the processor in question.
7781 * @p: the task pointer to set.
7783 * Description: This function must only be used when non-maskable interrupts
7784 * are serviced on a separate stack. It allows the architecture to switch the
7785 * notion of the current task on a cpu in a non-blocking manner. This function
7786 * must be called with all CPU's synchronized, and interrupts disabled, the
7787 * and caller must save the original value of the current task (see
7788 * curr_task() above) and restore that value before reenabling interrupts and
7789 * re-starting the system.
7791 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7793 void set_curr_task(int cpu
, struct task_struct
*p
)
7800 #ifdef CONFIG_CGROUP_SCHED
7801 /* task_group_lock serializes the addition/removal of task groups */
7802 static DEFINE_SPINLOCK(task_group_lock
);
7804 static void free_sched_group(struct task_group
*tg
)
7806 free_fair_sched_group(tg
);
7807 free_rt_sched_group(tg
);
7809 kmem_cache_free(task_group_cache
, tg
);
7812 /* allocate runqueue etc for a new task group */
7813 struct task_group
*sched_create_group(struct task_group
*parent
)
7815 struct task_group
*tg
;
7817 tg
= kmem_cache_alloc(task_group_cache
, GFP_KERNEL
| __GFP_ZERO
);
7819 return ERR_PTR(-ENOMEM
);
7821 if (!alloc_fair_sched_group(tg
, parent
))
7824 if (!alloc_rt_sched_group(tg
, parent
))
7830 free_sched_group(tg
);
7831 return ERR_PTR(-ENOMEM
);
7834 void sched_online_group(struct task_group
*tg
, struct task_group
*parent
)
7836 unsigned long flags
;
7838 spin_lock_irqsave(&task_group_lock
, flags
);
7839 list_add_rcu(&tg
->list
, &task_groups
);
7841 WARN_ON(!parent
); /* root should already exist */
7843 tg
->parent
= parent
;
7844 INIT_LIST_HEAD(&tg
->children
);
7845 list_add_rcu(&tg
->siblings
, &parent
->children
);
7846 spin_unlock_irqrestore(&task_group_lock
, flags
);
7849 /* rcu callback to free various structures associated with a task group */
7850 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7852 /* now it should be safe to free those cfs_rqs */
7853 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7856 /* Destroy runqueue etc associated with a task group */
7857 void sched_destroy_group(struct task_group
*tg
)
7859 /* wait for possible concurrent references to cfs_rqs complete */
7860 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7863 void sched_offline_group(struct task_group
*tg
)
7865 unsigned long flags
;
7868 /* end participation in shares distribution */
7869 for_each_possible_cpu(i
)
7870 unregister_fair_sched_group(tg
, i
);
7872 spin_lock_irqsave(&task_group_lock
, flags
);
7873 list_del_rcu(&tg
->list
);
7874 list_del_rcu(&tg
->siblings
);
7875 spin_unlock_irqrestore(&task_group_lock
, flags
);
7878 /* change task's runqueue when it moves between groups.
7879 * The caller of this function should have put the task in its new group
7880 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7881 * reflect its new group.
7883 void sched_move_task(struct task_struct
*tsk
)
7885 struct task_group
*tg
;
7886 int queued
, running
;
7887 unsigned long flags
;
7890 rq
= task_rq_lock(tsk
, &flags
);
7892 running
= task_current(rq
, tsk
);
7893 queued
= task_on_rq_queued(tsk
);
7896 dequeue_task(rq
, tsk
, DEQUEUE_SAVE
);
7897 if (unlikely(running
))
7898 put_prev_task(rq
, tsk
);
7901 * All callers are synchronized by task_rq_lock(); we do not use RCU
7902 * which is pointless here. Thus, we pass "true" to task_css_check()
7903 * to prevent lockdep warnings.
7905 tg
= container_of(task_css_check(tsk
, cpu_cgrp_id
, true),
7906 struct task_group
, css
);
7907 tg
= autogroup_task_group(tsk
, tg
);
7908 tsk
->sched_task_group
= tg
;
7910 #ifdef CONFIG_FAIR_GROUP_SCHED
7911 if (tsk
->sched_class
->task_move_group
)
7912 tsk
->sched_class
->task_move_group(tsk
);
7915 set_task_rq(tsk
, task_cpu(tsk
));
7917 if (unlikely(running
))
7918 tsk
->sched_class
->set_curr_task(rq
);
7920 enqueue_task(rq
, tsk
, ENQUEUE_RESTORE
);
7922 task_rq_unlock(rq
, tsk
, &flags
);
7924 #endif /* CONFIG_CGROUP_SCHED */
7926 #ifdef CONFIG_RT_GROUP_SCHED
7928 * Ensure that the real time constraints are schedulable.
7930 static DEFINE_MUTEX(rt_constraints_mutex
);
7932 /* Must be called with tasklist_lock held */
7933 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7935 struct task_struct
*g
, *p
;
7938 * Autogroups do not have RT tasks; see autogroup_create().
7940 if (task_group_is_autogroup(tg
))
7943 for_each_process_thread(g
, p
) {
7944 if (rt_task(p
) && task_group(p
) == tg
)
7951 struct rt_schedulable_data
{
7952 struct task_group
*tg
;
7957 static int tg_rt_schedulable(struct task_group
*tg
, void *data
)
7959 struct rt_schedulable_data
*d
= data
;
7960 struct task_group
*child
;
7961 unsigned long total
, sum
= 0;
7962 u64 period
, runtime
;
7964 period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
7965 runtime
= tg
->rt_bandwidth
.rt_runtime
;
7968 period
= d
->rt_period
;
7969 runtime
= d
->rt_runtime
;
7973 * Cannot have more runtime than the period.
7975 if (runtime
> period
&& runtime
!= RUNTIME_INF
)
7979 * Ensure we don't starve existing RT tasks.
7981 if (rt_bandwidth_enabled() && !runtime
&& tg_has_rt_tasks(tg
))
7984 total
= to_ratio(period
, runtime
);
7987 * Nobody can have more than the global setting allows.
7989 if (total
> to_ratio(global_rt_period(), global_rt_runtime()))
7993 * The sum of our children's runtime should not exceed our own.
7995 list_for_each_entry_rcu(child
, &tg
->children
, siblings
) {
7996 period
= ktime_to_ns(child
->rt_bandwidth
.rt_period
);
7997 runtime
= child
->rt_bandwidth
.rt_runtime
;
7999 if (child
== d
->tg
) {
8000 period
= d
->rt_period
;
8001 runtime
= d
->rt_runtime
;
8004 sum
+= to_ratio(period
, runtime
);
8013 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
8017 struct rt_schedulable_data data
= {
8019 .rt_period
= period
,
8020 .rt_runtime
= runtime
,
8024 ret
= walk_tg_tree(tg_rt_schedulable
, tg_nop
, &data
);
8030 static int tg_set_rt_bandwidth(struct task_group
*tg
,
8031 u64 rt_period
, u64 rt_runtime
)
8036 * Disallowing the root group RT runtime is BAD, it would disallow the
8037 * kernel creating (and or operating) RT threads.
8039 if (tg
== &root_task_group
&& rt_runtime
== 0)
8042 /* No period doesn't make any sense. */
8046 mutex_lock(&rt_constraints_mutex
);
8047 read_lock(&tasklist_lock
);
8048 err
= __rt_schedulable(tg
, rt_period
, rt_runtime
);
8052 raw_spin_lock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
8053 tg
->rt_bandwidth
.rt_period
= ns_to_ktime(rt_period
);
8054 tg
->rt_bandwidth
.rt_runtime
= rt_runtime
;
8056 for_each_possible_cpu(i
) {
8057 struct rt_rq
*rt_rq
= tg
->rt_rq
[i
];
8059 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
8060 rt_rq
->rt_runtime
= rt_runtime
;
8061 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
8063 raw_spin_unlock_irq(&tg
->rt_bandwidth
.rt_runtime_lock
);
8065 read_unlock(&tasklist_lock
);
8066 mutex_unlock(&rt_constraints_mutex
);
8071 static int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
8073 u64 rt_runtime
, rt_period
;
8075 rt_period
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8076 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
8077 if (rt_runtime_us
< 0)
8078 rt_runtime
= RUNTIME_INF
;
8080 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
8083 static long sched_group_rt_runtime(struct task_group
*tg
)
8087 if (tg
->rt_bandwidth
.rt_runtime
== RUNTIME_INF
)
8090 rt_runtime_us
= tg
->rt_bandwidth
.rt_runtime
;
8091 do_div(rt_runtime_us
, NSEC_PER_USEC
);
8092 return rt_runtime_us
;
8095 static int sched_group_set_rt_period(struct task_group
*tg
, u64 rt_period_us
)
8097 u64 rt_runtime
, rt_period
;
8099 rt_period
= rt_period_us
* NSEC_PER_USEC
;
8100 rt_runtime
= tg
->rt_bandwidth
.rt_runtime
;
8102 return tg_set_rt_bandwidth(tg
, rt_period
, rt_runtime
);
8105 static long sched_group_rt_period(struct task_group
*tg
)
8109 rt_period_us
= ktime_to_ns(tg
->rt_bandwidth
.rt_period
);
8110 do_div(rt_period_us
, NSEC_PER_USEC
);
8111 return rt_period_us
;
8113 #endif /* CONFIG_RT_GROUP_SCHED */
8115 #ifdef CONFIG_RT_GROUP_SCHED
8116 static int sched_rt_global_constraints(void)
8120 mutex_lock(&rt_constraints_mutex
);
8121 read_lock(&tasklist_lock
);
8122 ret
= __rt_schedulable(NULL
, 0, 0);
8123 read_unlock(&tasklist_lock
);
8124 mutex_unlock(&rt_constraints_mutex
);
8129 static int sched_rt_can_attach(struct task_group
*tg
, struct task_struct
*tsk
)
8131 /* Don't accept realtime tasks when there is no way for them to run */
8132 if (rt_task(tsk
) && tg
->rt_bandwidth
.rt_runtime
== 0)
8138 #else /* !CONFIG_RT_GROUP_SCHED */
8139 static int sched_rt_global_constraints(void)
8141 unsigned long flags
;
8144 raw_spin_lock_irqsave(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8145 for_each_possible_cpu(i
) {
8146 struct rt_rq
*rt_rq
= &cpu_rq(i
)->rt
;
8148 raw_spin_lock(&rt_rq
->rt_runtime_lock
);
8149 rt_rq
->rt_runtime
= global_rt_runtime();
8150 raw_spin_unlock(&rt_rq
->rt_runtime_lock
);
8152 raw_spin_unlock_irqrestore(&def_rt_bandwidth
.rt_runtime_lock
, flags
);
8156 #endif /* CONFIG_RT_GROUP_SCHED */
8158 static int sched_dl_global_validate(void)
8160 u64 runtime
= global_rt_runtime();
8161 u64 period
= global_rt_period();
8162 u64 new_bw
= to_ratio(period
, runtime
);
8165 unsigned long flags
;
8168 * Here we want to check the bandwidth not being set to some
8169 * value smaller than the currently allocated bandwidth in
8170 * any of the root_domains.
8172 * FIXME: Cycling on all the CPUs is overdoing, but simpler than
8173 * cycling on root_domains... Discussion on different/better
8174 * solutions is welcome!
8176 for_each_possible_cpu(cpu
) {
8177 rcu_read_lock_sched();
8178 dl_b
= dl_bw_of(cpu
);
8180 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
8181 if (new_bw
< dl_b
->total_bw
)
8183 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
8185 rcu_read_unlock_sched();
8194 static void sched_dl_do_global(void)
8199 unsigned long flags
;
8201 def_dl_bandwidth
.dl_period
= global_rt_period();
8202 def_dl_bandwidth
.dl_runtime
= global_rt_runtime();
8204 if (global_rt_runtime() != RUNTIME_INF
)
8205 new_bw
= to_ratio(global_rt_period(), global_rt_runtime());
8208 * FIXME: As above...
8210 for_each_possible_cpu(cpu
) {
8211 rcu_read_lock_sched();
8212 dl_b
= dl_bw_of(cpu
);
8214 raw_spin_lock_irqsave(&dl_b
->lock
, flags
);
8216 raw_spin_unlock_irqrestore(&dl_b
->lock
, flags
);
8218 rcu_read_unlock_sched();
8222 static int sched_rt_global_validate(void)
8224 if (sysctl_sched_rt_period
<= 0)
8227 if ((sysctl_sched_rt_runtime
!= RUNTIME_INF
) &&
8228 (sysctl_sched_rt_runtime
> sysctl_sched_rt_period
))
8234 static void sched_rt_do_global(void)
8236 def_rt_bandwidth
.rt_runtime
= global_rt_runtime();
8237 def_rt_bandwidth
.rt_period
= ns_to_ktime(global_rt_period());
8240 int sched_rt_handler(struct ctl_table
*table
, int write
,
8241 void __user
*buffer
, size_t *lenp
,
8244 int old_period
, old_runtime
;
8245 static DEFINE_MUTEX(mutex
);
8249 old_period
= sysctl_sched_rt_period
;
8250 old_runtime
= sysctl_sched_rt_runtime
;
8252 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
8254 if (!ret
&& write
) {
8255 ret
= sched_rt_global_validate();
8259 ret
= sched_dl_global_validate();
8263 ret
= sched_rt_global_constraints();
8267 sched_rt_do_global();
8268 sched_dl_do_global();
8272 sysctl_sched_rt_period
= old_period
;
8273 sysctl_sched_rt_runtime
= old_runtime
;
8275 mutex_unlock(&mutex
);
8280 int sched_rr_handler(struct ctl_table
*table
, int write
,
8281 void __user
*buffer
, size_t *lenp
,
8285 static DEFINE_MUTEX(mutex
);
8288 ret
= proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
8289 /* make sure that internally we keep jiffies */
8290 /* also, writing zero resets timeslice to default */
8291 if (!ret
&& write
) {
8292 sched_rr_timeslice
= sched_rr_timeslice
<= 0 ?
8293 RR_TIMESLICE
: msecs_to_jiffies(sched_rr_timeslice
);
8295 mutex_unlock(&mutex
);
8299 #ifdef CONFIG_CGROUP_SCHED
8301 static inline struct task_group
*css_tg(struct cgroup_subsys_state
*css
)
8303 return css
? container_of(css
, struct task_group
, css
) : NULL
;
8306 static struct cgroup_subsys_state
*
8307 cpu_cgroup_css_alloc(struct cgroup_subsys_state
*parent_css
)
8309 struct task_group
*parent
= css_tg(parent_css
);
8310 struct task_group
*tg
;
8313 /* This is early initialization for the top cgroup */
8314 return &root_task_group
.css
;
8317 tg
= sched_create_group(parent
);
8319 return ERR_PTR(-ENOMEM
);
8324 static int cpu_cgroup_css_online(struct cgroup_subsys_state
*css
)
8326 struct task_group
*tg
= css_tg(css
);
8327 struct task_group
*parent
= css_tg(css
->parent
);
8330 sched_online_group(tg
, parent
);
8334 static void cpu_cgroup_css_free(struct cgroup_subsys_state
*css
)
8336 struct task_group
*tg
= css_tg(css
);
8338 sched_destroy_group(tg
);
8341 static void cpu_cgroup_css_offline(struct cgroup_subsys_state
*css
)
8343 struct task_group
*tg
= css_tg(css
);
8345 sched_offline_group(tg
);
8348 static void cpu_cgroup_fork(struct task_struct
*task
)
8350 sched_move_task(task
);
8353 static int cpu_cgroup_can_attach(struct cgroup_taskset
*tset
)
8355 struct task_struct
*task
;
8356 struct cgroup_subsys_state
*css
;
8358 cgroup_taskset_for_each(task
, css
, tset
) {
8359 #ifdef CONFIG_RT_GROUP_SCHED
8360 if (!sched_rt_can_attach(css_tg(css
), task
))
8363 /* We don't support RT-tasks being in separate groups */
8364 if (task
->sched_class
!= &fair_sched_class
)
8371 static void cpu_cgroup_attach(struct cgroup_taskset
*tset
)
8373 struct task_struct
*task
;
8374 struct cgroup_subsys_state
*css
;
8376 cgroup_taskset_for_each(task
, css
, tset
)
8377 sched_move_task(task
);
8380 #ifdef CONFIG_FAIR_GROUP_SCHED
8381 static int cpu_shares_write_u64(struct cgroup_subsys_state
*css
,
8382 struct cftype
*cftype
, u64 shareval
)
8384 return sched_group_set_shares(css_tg(css
), scale_load(shareval
));
8387 static u64
cpu_shares_read_u64(struct cgroup_subsys_state
*css
,
8390 struct task_group
*tg
= css_tg(css
);
8392 return (u64
) scale_load_down(tg
->shares
);
8395 #ifdef CONFIG_CFS_BANDWIDTH
8396 static DEFINE_MUTEX(cfs_constraints_mutex
);
8398 const u64 max_cfs_quota_period
= 1 * NSEC_PER_SEC
; /* 1s */
8399 const u64 min_cfs_quota_period
= 1 * NSEC_PER_MSEC
; /* 1ms */
8401 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
);
8403 static int tg_set_cfs_bandwidth(struct task_group
*tg
, u64 period
, u64 quota
)
8405 int i
, ret
= 0, runtime_enabled
, runtime_was_enabled
;
8406 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8408 if (tg
== &root_task_group
)
8412 * Ensure we have at some amount of bandwidth every period. This is
8413 * to prevent reaching a state of large arrears when throttled via
8414 * entity_tick() resulting in prolonged exit starvation.
8416 if (quota
< min_cfs_quota_period
|| period
< min_cfs_quota_period
)
8420 * Likewise, bound things on the otherside by preventing insane quota
8421 * periods. This also allows us to normalize in computing quota
8424 if (period
> max_cfs_quota_period
)
8428 * Prevent race between setting of cfs_rq->runtime_enabled and
8429 * unthrottle_offline_cfs_rqs().
8432 mutex_lock(&cfs_constraints_mutex
);
8433 ret
= __cfs_schedulable(tg
, period
, quota
);
8437 runtime_enabled
= quota
!= RUNTIME_INF
;
8438 runtime_was_enabled
= cfs_b
->quota
!= RUNTIME_INF
;
8440 * If we need to toggle cfs_bandwidth_used, off->on must occur
8441 * before making related changes, and on->off must occur afterwards
8443 if (runtime_enabled
&& !runtime_was_enabled
)
8444 cfs_bandwidth_usage_inc();
8445 raw_spin_lock_irq(&cfs_b
->lock
);
8446 cfs_b
->period
= ns_to_ktime(period
);
8447 cfs_b
->quota
= quota
;
8449 __refill_cfs_bandwidth_runtime(cfs_b
);
8450 /* restart the period timer (if active) to handle new period expiry */
8451 if (runtime_enabled
)
8452 start_cfs_bandwidth(cfs_b
);
8453 raw_spin_unlock_irq(&cfs_b
->lock
);
8455 for_each_online_cpu(i
) {
8456 struct cfs_rq
*cfs_rq
= tg
->cfs_rq
[i
];
8457 struct rq
*rq
= cfs_rq
->rq
;
8459 raw_spin_lock_irq(&rq
->lock
);
8460 cfs_rq
->runtime_enabled
= runtime_enabled
;
8461 cfs_rq
->runtime_remaining
= 0;
8463 if (cfs_rq
->throttled
)
8464 unthrottle_cfs_rq(cfs_rq
);
8465 raw_spin_unlock_irq(&rq
->lock
);
8467 if (runtime_was_enabled
&& !runtime_enabled
)
8468 cfs_bandwidth_usage_dec();
8470 mutex_unlock(&cfs_constraints_mutex
);
8476 int tg_set_cfs_quota(struct task_group
*tg
, long cfs_quota_us
)
8480 period
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8481 if (cfs_quota_us
< 0)
8482 quota
= RUNTIME_INF
;
8484 quota
= (u64
)cfs_quota_us
* NSEC_PER_USEC
;
8486 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8489 long tg_get_cfs_quota(struct task_group
*tg
)
8493 if (tg
->cfs_bandwidth
.quota
== RUNTIME_INF
)
8496 quota_us
= tg
->cfs_bandwidth
.quota
;
8497 do_div(quota_us
, NSEC_PER_USEC
);
8502 int tg_set_cfs_period(struct task_group
*tg
, long cfs_period_us
)
8506 period
= (u64
)cfs_period_us
* NSEC_PER_USEC
;
8507 quota
= tg
->cfs_bandwidth
.quota
;
8509 return tg_set_cfs_bandwidth(tg
, period
, quota
);
8512 long tg_get_cfs_period(struct task_group
*tg
)
8516 cfs_period_us
= ktime_to_ns(tg
->cfs_bandwidth
.period
);
8517 do_div(cfs_period_us
, NSEC_PER_USEC
);
8519 return cfs_period_us
;
8522 static s64
cpu_cfs_quota_read_s64(struct cgroup_subsys_state
*css
,
8525 return tg_get_cfs_quota(css_tg(css
));
8528 static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state
*css
,
8529 struct cftype
*cftype
, s64 cfs_quota_us
)
8531 return tg_set_cfs_quota(css_tg(css
), cfs_quota_us
);
8534 static u64
cpu_cfs_period_read_u64(struct cgroup_subsys_state
*css
,
8537 return tg_get_cfs_period(css_tg(css
));
8540 static int cpu_cfs_period_write_u64(struct cgroup_subsys_state
*css
,
8541 struct cftype
*cftype
, u64 cfs_period_us
)
8543 return tg_set_cfs_period(css_tg(css
), cfs_period_us
);
8546 struct cfs_schedulable_data
{
8547 struct task_group
*tg
;
8552 * normalize group quota/period to be quota/max_period
8553 * note: units are usecs
8555 static u64
normalize_cfs_quota(struct task_group
*tg
,
8556 struct cfs_schedulable_data
*d
)
8564 period
= tg_get_cfs_period(tg
);
8565 quota
= tg_get_cfs_quota(tg
);
8568 /* note: these should typically be equivalent */
8569 if (quota
== RUNTIME_INF
|| quota
== -1)
8572 return to_ratio(period
, quota
);
8575 static int tg_cfs_schedulable_down(struct task_group
*tg
, void *data
)
8577 struct cfs_schedulable_data
*d
= data
;
8578 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8579 s64 quota
= 0, parent_quota
= -1;
8582 quota
= RUNTIME_INF
;
8584 struct cfs_bandwidth
*parent_b
= &tg
->parent
->cfs_bandwidth
;
8586 quota
= normalize_cfs_quota(tg
, d
);
8587 parent_quota
= parent_b
->hierarchical_quota
;
8590 * ensure max(child_quota) <= parent_quota, inherit when no
8593 if (quota
== RUNTIME_INF
)
8594 quota
= parent_quota
;
8595 else if (parent_quota
!= RUNTIME_INF
&& quota
> parent_quota
)
8598 cfs_b
->hierarchical_quota
= quota
;
8603 static int __cfs_schedulable(struct task_group
*tg
, u64 period
, u64 quota
)
8606 struct cfs_schedulable_data data
= {
8612 if (quota
!= RUNTIME_INF
) {
8613 do_div(data
.period
, NSEC_PER_USEC
);
8614 do_div(data
.quota
, NSEC_PER_USEC
);
8618 ret
= walk_tg_tree(tg_cfs_schedulable_down
, tg_nop
, &data
);
8624 static int cpu_stats_show(struct seq_file
*sf
, void *v
)
8626 struct task_group
*tg
= css_tg(seq_css(sf
));
8627 struct cfs_bandwidth
*cfs_b
= &tg
->cfs_bandwidth
;
8629 seq_printf(sf
, "nr_periods %d\n", cfs_b
->nr_periods
);
8630 seq_printf(sf
, "nr_throttled %d\n", cfs_b
->nr_throttled
);
8631 seq_printf(sf
, "throttled_time %llu\n", cfs_b
->throttled_time
);
8635 #endif /* CONFIG_CFS_BANDWIDTH */
8636 #endif /* CONFIG_FAIR_GROUP_SCHED */
8638 #ifdef CONFIG_RT_GROUP_SCHED
8639 static int cpu_rt_runtime_write(struct cgroup_subsys_state
*css
,
8640 struct cftype
*cft
, s64 val
)
8642 return sched_group_set_rt_runtime(css_tg(css
), val
);
8645 static s64
cpu_rt_runtime_read(struct cgroup_subsys_state
*css
,
8648 return sched_group_rt_runtime(css_tg(css
));
8651 static int cpu_rt_period_write_uint(struct cgroup_subsys_state
*css
,
8652 struct cftype
*cftype
, u64 rt_period_us
)
8654 return sched_group_set_rt_period(css_tg(css
), rt_period_us
);
8657 static u64
cpu_rt_period_read_uint(struct cgroup_subsys_state
*css
,
8660 return sched_group_rt_period(css_tg(css
));
8662 #endif /* CONFIG_RT_GROUP_SCHED */
8664 static struct cftype cpu_files
[] = {
8665 #ifdef CONFIG_FAIR_GROUP_SCHED
8668 .read_u64
= cpu_shares_read_u64
,
8669 .write_u64
= cpu_shares_write_u64
,
8672 #ifdef CONFIG_CFS_BANDWIDTH
8674 .name
= "cfs_quota_us",
8675 .read_s64
= cpu_cfs_quota_read_s64
,
8676 .write_s64
= cpu_cfs_quota_write_s64
,
8679 .name
= "cfs_period_us",
8680 .read_u64
= cpu_cfs_period_read_u64
,
8681 .write_u64
= cpu_cfs_period_write_u64
,
8685 .seq_show
= cpu_stats_show
,
8688 #ifdef CONFIG_RT_GROUP_SCHED
8690 .name
= "rt_runtime_us",
8691 .read_s64
= cpu_rt_runtime_read
,
8692 .write_s64
= cpu_rt_runtime_write
,
8695 .name
= "rt_period_us",
8696 .read_u64
= cpu_rt_period_read_uint
,
8697 .write_u64
= cpu_rt_period_write_uint
,
8703 struct cgroup_subsys cpu_cgrp_subsys
= {
8704 .css_alloc
= cpu_cgroup_css_alloc
,
8705 .css_free
= cpu_cgroup_css_free
,
8706 .css_online
= cpu_cgroup_css_online
,
8707 .css_offline
= cpu_cgroup_css_offline
,
8708 .fork
= cpu_cgroup_fork
,
8709 .can_attach
= cpu_cgroup_can_attach
,
8710 .attach
= cpu_cgroup_attach
,
8711 .legacy_cftypes
= cpu_files
,
8715 #endif /* CONFIG_CGROUP_SCHED */
8717 void dump_cpu_task(int cpu
)
8719 pr_info("Task dump for CPU %d:\n", cpu
);
8720 sched_show_task(cpu_curr(cpu
));
8724 * Nice levels are multiplicative, with a gentle 10% change for every
8725 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
8726 * nice 1, it will get ~10% less CPU time than another CPU-bound task
8727 * that remained on nice 0.
8729 * The "10% effect" is relative and cumulative: from _any_ nice level,
8730 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
8731 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
8732 * If a task goes up by ~10% and another task goes down by ~10% then
8733 * the relative distance between them is ~25%.)
8735 const int sched_prio_to_weight
[40] = {
8736 /* -20 */ 88761, 71755, 56483, 46273, 36291,
8737 /* -15 */ 29154, 23254, 18705, 14949, 11916,
8738 /* -10 */ 9548, 7620, 6100, 4904, 3906,
8739 /* -5 */ 3121, 2501, 1991, 1586, 1277,
8740 /* 0 */ 1024, 820, 655, 526, 423,
8741 /* 5 */ 335, 272, 215, 172, 137,
8742 /* 10 */ 110, 87, 70, 56, 45,
8743 /* 15 */ 36, 29, 23, 18, 15,
8747 * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
8749 * In cases where the weight does not change often, we can use the
8750 * precalculated inverse to speed up arithmetics by turning divisions
8751 * into multiplications:
8753 const u32 sched_prio_to_wmult
[40] = {
8754 /* -20 */ 48388, 59856, 76040, 92818, 118348,
8755 /* -15 */ 147320, 184698, 229616, 287308, 360437,
8756 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
8757 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
8758 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
8759 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
8760 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
8761 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,