4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
19 * 2007-04-15 Work begun on replacing all interactivity tuning with a
20 * fair scheduling design by Con Kolivas.
21 * 2007-05-05 Load balancing (smp-nice) and other improvements
23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26 * Thomas Gleixner, Mike Kravetz
30 #include <linux/module.h>
31 #include <linux/nmi.h>
32 #include <linux/init.h>
33 #include <linux/uaccess.h>
34 #include <linux/highmem.h>
35 #include <linux/smp_lock.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/security.h>
43 #include <linux/notifier.h>
44 #include <linux/profile.h>
45 #include <linux/freezer.h>
46 #include <linux/vmalloc.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/smp.h>
51 #include <linux/threads.h>
52 #include <linux/timer.h>
53 #include <linux/rcupdate.h>
54 #include <linux/cpu.h>
55 #include <linux/cpuset.h>
56 #include <linux/percpu.h>
57 #include <linux/kthread.h>
58 #include <linux/seq_file.h>
59 #include <linux/sysctl.h>
60 #include <linux/syscalls.h>
61 #include <linux/times.h>
62 #include <linux/tsacct_kern.h>
63 #include <linux/kprobes.h>
64 #include <linux/delayacct.h>
65 #include <linux/reciprocal_div.h>
66 #include <linux/unistd.h>
67 #include <linux/pagemap.h>
68 #include <linux/hrtimer.h>
69 #include <linux/tick.h>
72 #include <asm/irq_regs.h>
75 * Scheduler clock - returns current time in nanosec units.
76 * This is default implementation.
77 * Architectures and sub-architectures can override this.
79 unsigned long long __attribute__((weak
)) sched_clock(void)
81 return (unsigned long long)jiffies
* (NSEC_PER_SEC
/ HZ
);
85 * Convert user-nice values [ -20 ... 0 ... 19 ]
86 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
89 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
90 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
91 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
94 * 'User priority' is the nice value converted to something we
95 * can work with better when scaling various scheduler parameters,
96 * it's a [ 0 ... 39 ] range.
98 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
99 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
100 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
103 * Helpers for converting nanosecond timing to jiffy resolution
105 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
107 #define NICE_0_LOAD SCHED_LOAD_SCALE
108 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
111 * These are the 'tuning knobs' of the scheduler:
113 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
114 * Timeslices get refilled after they expire.
116 #define DEF_TIMESLICE (100 * HZ / 1000)
120 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
121 * Since cpu_power is a 'constant', we can use a reciprocal divide.
123 static inline u32
sg_div_cpu_power(const struct sched_group
*sg
, u32 load
)
125 return reciprocal_divide(load
, sg
->reciprocal_cpu_power
);
129 * Each time a sched group cpu_power is changed,
130 * we must compute its reciprocal value
132 static inline void sg_inc_cpu_power(struct sched_group
*sg
, u32 val
)
134 sg
->__cpu_power
+= val
;
135 sg
->reciprocal_cpu_power
= reciprocal_value(sg
->__cpu_power
);
139 static inline int rt_policy(int policy
)
141 if (unlikely(policy
== SCHED_FIFO
) || unlikely(policy
== SCHED_RR
))
146 static inline int task_has_rt_policy(struct task_struct
*p
)
148 return rt_policy(p
->policy
);
152 * This is the priority-queue data structure of the RT scheduling class:
154 struct rt_prio_array
{
155 DECLARE_BITMAP(bitmap
, MAX_RT_PRIO
+1); /* include 1 bit for delimiter */
156 struct list_head queue
[MAX_RT_PRIO
];
159 #ifdef CONFIG_GROUP_SCHED
161 #include <linux/cgroup.h>
165 static LIST_HEAD(task_groups
);
167 /* task group related information */
169 #ifdef CONFIG_CGROUP_SCHED
170 struct cgroup_subsys_state css
;
173 #ifdef CONFIG_FAIR_GROUP_SCHED
174 /* schedulable entities of this group on each cpu */
175 struct sched_entity
**se
;
176 /* runqueue "owned" by this group on each cpu */
177 struct cfs_rq
**cfs_rq
;
178 unsigned long shares
;
181 #ifdef CONFIG_RT_GROUP_SCHED
182 struct sched_rt_entity
**rt_se
;
183 struct rt_rq
**rt_rq
;
189 struct list_head list
;
192 #ifdef CONFIG_FAIR_GROUP_SCHED
193 /* Default task group's sched entity on each cpu */
194 static DEFINE_PER_CPU(struct sched_entity
, init_sched_entity
);
195 /* Default task group's cfs_rq on each cpu */
196 static DEFINE_PER_CPU(struct cfs_rq
, init_cfs_rq
) ____cacheline_aligned_in_smp
;
198 static struct sched_entity
*init_sched_entity_p
[NR_CPUS
];
199 static struct cfs_rq
*init_cfs_rq_p
[NR_CPUS
];
202 #ifdef CONFIG_RT_GROUP_SCHED
203 static DEFINE_PER_CPU(struct sched_rt_entity
, init_sched_rt_entity
);
204 static DEFINE_PER_CPU(struct rt_rq
, init_rt_rq
) ____cacheline_aligned_in_smp
;
206 static struct sched_rt_entity
*init_sched_rt_entity_p
[NR_CPUS
];
207 static struct rt_rq
*init_rt_rq_p
[NR_CPUS
];
210 /* task_group_lock serializes add/remove of task groups and also changes to
211 * a task group's cpu shares.
213 static DEFINE_SPINLOCK(task_group_lock
);
215 /* doms_cur_mutex serializes access to doms_cur[] array */
216 static DEFINE_MUTEX(doms_cur_mutex
);
218 #ifdef CONFIG_FAIR_GROUP_SCHED
219 #ifdef CONFIG_USER_SCHED
220 # define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
222 # define INIT_TASK_GROUP_LOAD NICE_0_LOAD
225 static int init_task_group_load
= INIT_TASK_GROUP_LOAD
;
228 /* Default task group.
229 * Every task in system belong to this group at bootup.
231 struct task_group init_task_group
= {
232 #ifdef CONFIG_FAIR_GROUP_SCHED
233 .se
= init_sched_entity_p
,
234 .cfs_rq
= init_cfs_rq_p
,
237 #ifdef CONFIG_RT_GROUP_SCHED
238 .rt_se
= init_sched_rt_entity_p
,
239 .rt_rq
= init_rt_rq_p
,
243 /* return group to which a task belongs */
244 static inline struct task_group
*task_group(struct task_struct
*p
)
246 struct task_group
*tg
;
248 #ifdef CONFIG_USER_SCHED
250 #elif defined(CONFIG_CGROUP_SCHED)
251 tg
= container_of(task_subsys_state(p
, cpu_cgroup_subsys_id
),
252 struct task_group
, css
);
254 tg
= &init_task_group
;
259 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
260 static inline void set_task_rq(struct task_struct
*p
, unsigned int cpu
)
262 #ifdef CONFIG_FAIR_GROUP_SCHED
263 p
->se
.cfs_rq
= task_group(p
)->cfs_rq
[cpu
];
264 p
->se
.parent
= task_group(p
)->se
[cpu
];
267 #ifdef CONFIG_RT_GROUP_SCHED
268 p
->rt
.rt_rq
= task_group(p
)->rt_rq
[cpu
];
269 p
->rt
.parent
= task_group(p
)->rt_se
[cpu
];
273 static inline void lock_doms_cur(void)
275 mutex_lock(&doms_cur_mutex
);
278 static inline void unlock_doms_cur(void)
280 mutex_unlock(&doms_cur_mutex
);
285 static inline void set_task_rq(struct task_struct
*p
, unsigned int cpu
) { }
286 static inline void lock_doms_cur(void) { }
287 static inline void unlock_doms_cur(void) { }
289 #endif /* CONFIG_GROUP_SCHED */
291 /* CFS-related fields in a runqueue */
293 struct load_weight load
;
294 unsigned long nr_running
;
299 struct rb_root tasks_timeline
;
300 struct rb_node
*rb_leftmost
;
301 struct rb_node
*rb_load_balance_curr
;
302 /* 'curr' points to currently running entity on this cfs_rq.
303 * It is set to NULL otherwise (i.e when none are currently running).
305 struct sched_entity
*curr
, *next
;
307 unsigned long nr_spread_over
;
309 #ifdef CONFIG_FAIR_GROUP_SCHED
310 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
313 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
314 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
315 * (like users, containers etc.)
317 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
318 * list is used during load balance.
320 struct list_head leaf_cfs_rq_list
;
321 struct task_group
*tg
; /* group that "owns" this runqueue */
325 /* Real-Time classes' related field in a runqueue: */
327 struct rt_prio_array active
;
328 unsigned long rt_nr_running
;
329 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
330 int highest_prio
; /* highest queued rt task prio */
333 unsigned long rt_nr_migratory
;
339 #ifdef CONFIG_RT_GROUP_SCHED
340 unsigned long rt_nr_boosted
;
343 struct list_head leaf_rt_rq_list
;
344 struct task_group
*tg
;
345 struct sched_rt_entity
*rt_se
;
352 * We add the notion of a root-domain which will be used to define per-domain
353 * variables. Each exclusive cpuset essentially defines an island domain by
354 * fully partitioning the member cpus from any other cpuset. Whenever a new
355 * exclusive cpuset is created, we also create and attach a new root-domain
365 * The "RT overload" flag: it gets set if a CPU has more than
366 * one runnable RT task.
373 * By default the system creates a single root-domain with all cpus as
374 * members (mimicking the global state we have today).
376 static struct root_domain def_root_domain
;
381 * This is the main, per-CPU runqueue data structure.
383 * Locking rule: those places that want to lock multiple runqueues
384 * (such as the load balancing or the thread migration code), lock
385 * acquire operations must be ordered by ascending &runqueue.
392 * nr_running and cpu_load should be in the same cacheline because
393 * remote CPUs use both these fields when doing load calculation.
395 unsigned long nr_running
;
396 #define CPU_LOAD_IDX_MAX 5
397 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
398 unsigned char idle_at_tick
;
400 unsigned long last_tick_seen
;
401 unsigned char in_nohz_recently
;
403 /* capture load from *all* tasks on this cpu: */
404 struct load_weight load
;
405 unsigned long nr_load_updates
;
410 u64 rt_period_expire
;
413 #ifdef CONFIG_FAIR_GROUP_SCHED
414 /* list of leaf cfs_rq on this cpu: */
415 struct list_head leaf_cfs_rq_list
;
417 #ifdef CONFIG_RT_GROUP_SCHED
418 struct list_head leaf_rt_rq_list
;
422 * This is part of a global counter where only the total sum
423 * over all CPUs matters. A task can increase this counter on
424 * one CPU and if it got migrated afterwards it may decrease
425 * it on another CPU. Always updated under the runqueue lock:
427 unsigned long nr_uninterruptible
;
429 struct task_struct
*curr
, *idle
;
430 unsigned long next_balance
;
431 struct mm_struct
*prev_mm
;
433 u64 clock
, prev_clock_raw
;
436 unsigned int clock_warps
, clock_overflows
, clock_underflows
;
438 unsigned int clock_deep_idle_events
;
444 struct root_domain
*rd
;
445 struct sched_domain
*sd
;
447 /* For active balancing */
450 /* cpu of this runqueue: */
453 struct task_struct
*migration_thread
;
454 struct list_head migration_queue
;
457 #ifdef CONFIG_SCHED_HRTICK
458 unsigned long hrtick_flags
;
459 ktime_t hrtick_expire
;
460 struct hrtimer hrtick_timer
;
463 #ifdef CONFIG_SCHEDSTATS
465 struct sched_info rq_sched_info
;
467 /* sys_sched_yield() stats */
468 unsigned int yld_exp_empty
;
469 unsigned int yld_act_empty
;
470 unsigned int yld_both_empty
;
471 unsigned int yld_count
;
473 /* schedule() stats */
474 unsigned int sched_switch
;
475 unsigned int sched_count
;
476 unsigned int sched_goidle
;
478 /* try_to_wake_up() stats */
479 unsigned int ttwu_count
;
480 unsigned int ttwu_local
;
483 unsigned int bkl_count
;
485 struct lock_class_key rq_lock_key
;
488 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
490 static inline void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
)
492 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
);
495 static inline int cpu_of(struct rq
*rq
)
505 static inline bool nohz_on(int cpu
)
507 return tick_get_tick_sched(cpu
)->nohz_mode
!= NOHZ_MODE_INACTIVE
;
510 static inline u64
max_skipped_ticks(struct rq
*rq
)
512 return nohz_on(cpu_of(rq
)) ? jiffies
- rq
->last_tick_seen
+ 2 : 1;
515 static inline void update_last_tick_seen(struct rq
*rq
)
517 rq
->last_tick_seen
= jiffies
;
520 static inline u64
max_skipped_ticks(struct rq
*rq
)
525 static inline void update_last_tick_seen(struct rq
*rq
)
531 * Update the per-runqueue clock, as finegrained as the platform can give
532 * us, but without assuming monotonicity, etc.:
534 static void __update_rq_clock(struct rq
*rq
)
536 u64 prev_raw
= rq
->prev_clock_raw
;
537 u64 now
= sched_clock();
538 s64 delta
= now
- prev_raw
;
539 u64 clock
= rq
->clock
;
541 #ifdef CONFIG_SCHED_DEBUG
542 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
545 * Protect against sched_clock() occasionally going backwards:
547 if (unlikely(delta
< 0)) {
552 * Catch too large forward jumps too:
554 u64 max_jump
= max_skipped_ticks(rq
) * TICK_NSEC
;
555 u64 max_time
= rq
->tick_timestamp
+ max_jump
;
557 if (unlikely(clock
+ delta
> max_time
)) {
558 if (clock
< max_time
)
562 rq
->clock_overflows
++;
564 if (unlikely(delta
> rq
->clock_max_delta
))
565 rq
->clock_max_delta
= delta
;
570 rq
->prev_clock_raw
= now
;
574 static void update_rq_clock(struct rq
*rq
)
576 if (likely(smp_processor_id() == cpu_of(rq
)))
577 __update_rq_clock(rq
);
581 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
582 * See detach_destroy_domains: synchronize_sched for details.
584 * The domain tree of any CPU may only be accessed from within
585 * preempt-disabled sections.
587 #define for_each_domain(cpu, __sd) \
588 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
590 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
591 #define this_rq() (&__get_cpu_var(runqueues))
592 #define task_rq(p) cpu_rq(task_cpu(p))
593 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
595 unsigned long rt_needs_cpu(int cpu
)
597 struct rq
*rq
= cpu_rq(cpu
);
600 if (!rq
->rt_throttled
)
603 if (rq
->clock
> rq
->rt_period_expire
)
606 delta
= rq
->rt_period_expire
- rq
->clock
;
607 do_div(delta
, NSEC_PER_SEC
/ HZ
);
609 return (unsigned long)delta
;
613 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
615 #ifdef CONFIG_SCHED_DEBUG
616 # define const_debug __read_mostly
618 # define const_debug static const
622 * Debugging: various feature bits
625 SCHED_FEAT_NEW_FAIR_SLEEPERS
= 1,
626 SCHED_FEAT_WAKEUP_PREEMPT
= 2,
627 SCHED_FEAT_START_DEBIT
= 4,
628 SCHED_FEAT_AFFINE_WAKEUPS
= 8,
629 SCHED_FEAT_CACHE_HOT_BUDDY
= 16,
630 SCHED_FEAT_SYNC_WAKEUPS
= 32,
631 SCHED_FEAT_HRTICK
= 64,
632 SCHED_FEAT_DOUBLE_TICK
= 128,
635 const_debug
unsigned int sysctl_sched_features
=
636 SCHED_FEAT_NEW_FAIR_SLEEPERS
* 1 |
637 SCHED_FEAT_WAKEUP_PREEMPT
* 1 |
638 SCHED_FEAT_START_DEBIT
* 1 |
639 SCHED_FEAT_AFFINE_WAKEUPS
* 1 |
640 SCHED_FEAT_CACHE_HOT_BUDDY
* 1 |
641 SCHED_FEAT_SYNC_WAKEUPS
* 1 |
642 SCHED_FEAT_HRTICK
* 1 |
643 SCHED_FEAT_DOUBLE_TICK
* 0;
645 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
648 * Number of tasks to iterate in a single balance run.
649 * Limited because this is done with IRQs disabled.
651 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
654 * period over which we measure -rt task cpu usage in us.
657 unsigned int sysctl_sched_rt_period
= 1000000;
659 static __read_mostly
int scheduler_running
;
662 * part of the period that we allow rt tasks to run in us.
665 int sysctl_sched_rt_runtime
= 950000;
668 * single value that denotes runtime == period, ie unlimited time.
670 #define RUNTIME_INF ((u64)~0ULL)
672 static const unsigned long long time_sync_thresh
= 100000;
674 static DEFINE_PER_CPU(unsigned long long, time_offset
);
675 static DEFINE_PER_CPU(unsigned long long, prev_cpu_time
);
678 * Global lock which we take every now and then to synchronize
679 * the CPUs time. This method is not warp-safe, but it's good
680 * enough to synchronize slowly diverging time sources and thus
681 * it's good enough for tracing:
683 static DEFINE_SPINLOCK(time_sync_lock
);
684 static unsigned long long prev_global_time
;
686 static unsigned long long __sync_cpu_clock(cycles_t time
, int cpu
)
690 spin_lock_irqsave(&time_sync_lock
, flags
);
692 if (time
< prev_global_time
) {
693 per_cpu(time_offset
, cpu
) += prev_global_time
- time
;
694 time
= prev_global_time
;
696 prev_global_time
= time
;
699 spin_unlock_irqrestore(&time_sync_lock
, flags
);
704 static unsigned long long __cpu_clock(int cpu
)
706 unsigned long long now
;
711 * Only call sched_clock() if the scheduler has already been
712 * initialized (some code might call cpu_clock() very early):
714 if (unlikely(!scheduler_running
))
717 local_irq_save(flags
);
721 local_irq_restore(flags
);
727 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
728 * clock constructed from sched_clock():
730 unsigned long long cpu_clock(int cpu
)
732 unsigned long long prev_cpu_time
, time
, delta_time
;
734 prev_cpu_time
= per_cpu(prev_cpu_time
, cpu
);
735 time
= __cpu_clock(cpu
) + per_cpu(time_offset
, cpu
);
736 delta_time
= time
-prev_cpu_time
;
738 if (unlikely(delta_time
> time_sync_thresh
))
739 time
= __sync_cpu_clock(time
, cpu
);
743 EXPORT_SYMBOL_GPL(cpu_clock
);
745 #ifndef prepare_arch_switch
746 # define prepare_arch_switch(next) do { } while (0)
748 #ifndef finish_arch_switch
749 # define finish_arch_switch(prev) do { } while (0)
752 static inline int task_current(struct rq
*rq
, struct task_struct
*p
)
754 return rq
->curr
== p
;
757 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
758 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
760 return task_current(rq
, p
);
763 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
767 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
769 #ifdef CONFIG_DEBUG_SPINLOCK
770 /* this is a valid case when another task releases the spinlock */
771 rq
->lock
.owner
= current
;
774 * If we are tracking spinlock dependencies then we have to
775 * fix up the runqueue lock - which gets 'carried over' from
778 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
780 spin_unlock_irq(&rq
->lock
);
783 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
784 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
789 return task_current(rq
, p
);
793 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
797 * We can optimise this out completely for !SMP, because the
798 * SMP rebalancing from interrupt is the only thing that cares
803 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
804 spin_unlock_irq(&rq
->lock
);
806 spin_unlock(&rq
->lock
);
810 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
814 * After ->oncpu is cleared, the task can be moved to a different CPU.
815 * We must ensure this doesn't happen until the switch is completely
821 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
825 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
828 * __task_rq_lock - lock the runqueue a given task resides on.
829 * Must be called interrupts disabled.
831 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
835 struct rq
*rq
= task_rq(p
);
836 spin_lock(&rq
->lock
);
837 if (likely(rq
== task_rq(p
)))
839 spin_unlock(&rq
->lock
);
844 * task_rq_lock - lock the runqueue a given task resides on and disable
845 * interrupts. Note the ordering: we can safely lookup the task_rq without
846 * explicitly disabling preemption.
848 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
854 local_irq_save(*flags
);
856 spin_lock(&rq
->lock
);
857 if (likely(rq
== task_rq(p
)))
859 spin_unlock_irqrestore(&rq
->lock
, *flags
);
863 static void __task_rq_unlock(struct rq
*rq
)
866 spin_unlock(&rq
->lock
);
869 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
872 spin_unlock_irqrestore(&rq
->lock
, *flags
);
876 * this_rq_lock - lock this runqueue and disable interrupts.
878 static struct rq
*this_rq_lock(void)
885 spin_lock(&rq
->lock
);
891 * We are going deep-idle (irqs are disabled):
893 void sched_clock_idle_sleep_event(void)
895 struct rq
*rq
= cpu_rq(smp_processor_id());
897 spin_lock(&rq
->lock
);
898 __update_rq_clock(rq
);
899 spin_unlock(&rq
->lock
);
900 rq
->clock_deep_idle_events
++;
902 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
905 * We just idled delta nanoseconds (called with irqs disabled):
907 void sched_clock_idle_wakeup_event(u64 delta_ns
)
909 struct rq
*rq
= cpu_rq(smp_processor_id());
910 u64 now
= sched_clock();
912 rq
->idle_clock
+= delta_ns
;
914 * Override the previous timestamp and ignore all
915 * sched_clock() deltas that occured while we idled,
916 * and use the PM-provided delta_ns to advance the
919 spin_lock(&rq
->lock
);
920 rq
->prev_clock_raw
= now
;
921 rq
->clock
+= delta_ns
;
922 spin_unlock(&rq
->lock
);
923 touch_softlockup_watchdog();
925 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
927 static void __resched_task(struct task_struct
*p
, int tif_bit
);
929 static inline void resched_task(struct task_struct
*p
)
931 __resched_task(p
, TIF_NEED_RESCHED
);
934 #ifdef CONFIG_SCHED_HRTICK
936 * Use HR-timers to deliver accurate preemption points.
938 * Its all a bit involved since we cannot program an hrt while holding the
939 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
942 * When we get rescheduled we reprogram the hrtick_timer outside of the
945 static inline void resched_hrt(struct task_struct
*p
)
947 __resched_task(p
, TIF_HRTICK_RESCHED
);
950 static inline void resched_rq(struct rq
*rq
)
954 spin_lock_irqsave(&rq
->lock
, flags
);
955 resched_task(rq
->curr
);
956 spin_unlock_irqrestore(&rq
->lock
, flags
);
960 HRTICK_SET
, /* re-programm hrtick_timer */
961 HRTICK_RESET
, /* not a new slice */
966 * - enabled by features
967 * - hrtimer is actually high res
969 static inline int hrtick_enabled(struct rq
*rq
)
971 if (!sched_feat(HRTICK
))
973 return hrtimer_is_hres_active(&rq
->hrtick_timer
);
977 * Called to set the hrtick timer state.
979 * called with rq->lock held and irqs disabled
981 static void hrtick_start(struct rq
*rq
, u64 delay
, int reset
)
983 assert_spin_locked(&rq
->lock
);
986 * preempt at: now + delay
989 ktime_add_ns(rq
->hrtick_timer
.base
->get_time(), delay
);
991 * indicate we need to program the timer
993 __set_bit(HRTICK_SET
, &rq
->hrtick_flags
);
995 __set_bit(HRTICK_RESET
, &rq
->hrtick_flags
);
998 * New slices are called from the schedule path and don't need a
1002 resched_hrt(rq
->curr
);
1005 static void hrtick_clear(struct rq
*rq
)
1007 if (hrtimer_active(&rq
->hrtick_timer
))
1008 hrtimer_cancel(&rq
->hrtick_timer
);
1012 * Update the timer from the possible pending state.
1014 static void hrtick_set(struct rq
*rq
)
1018 unsigned long flags
;
1020 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
1022 spin_lock_irqsave(&rq
->lock
, flags
);
1023 set
= __test_and_clear_bit(HRTICK_SET
, &rq
->hrtick_flags
);
1024 reset
= __test_and_clear_bit(HRTICK_RESET
, &rq
->hrtick_flags
);
1025 time
= rq
->hrtick_expire
;
1026 clear_thread_flag(TIF_HRTICK_RESCHED
);
1027 spin_unlock_irqrestore(&rq
->lock
, flags
);
1030 hrtimer_start(&rq
->hrtick_timer
, time
, HRTIMER_MODE_ABS
);
1031 if (reset
&& !hrtimer_active(&rq
->hrtick_timer
))
1038 * High-resolution timer tick.
1039 * Runs from hardirq context with interrupts disabled.
1041 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
1043 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
1045 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
1047 spin_lock(&rq
->lock
);
1048 __update_rq_clock(rq
);
1049 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
1050 spin_unlock(&rq
->lock
);
1052 return HRTIMER_NORESTART
;
1055 static inline void init_rq_hrtick(struct rq
*rq
)
1057 rq
->hrtick_flags
= 0;
1058 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1059 rq
->hrtick_timer
.function
= hrtick
;
1060 rq
->hrtick_timer
.cb_mode
= HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
;
1063 void hrtick_resched(void)
1066 unsigned long flags
;
1068 if (!test_thread_flag(TIF_HRTICK_RESCHED
))
1071 local_irq_save(flags
);
1072 rq
= cpu_rq(smp_processor_id());
1074 local_irq_restore(flags
);
1077 static inline void hrtick_clear(struct rq
*rq
)
1081 static inline void hrtick_set(struct rq
*rq
)
1085 static inline void init_rq_hrtick(struct rq
*rq
)
1089 void hrtick_resched(void)
1095 * resched_task - mark a task 'to be rescheduled now'.
1097 * On UP this means the setting of the need_resched flag, on SMP it
1098 * might also involve a cross-CPU call to trigger the scheduler on
1103 #ifndef tsk_is_polling
1104 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1107 static void __resched_task(struct task_struct
*p
, int tif_bit
)
1111 assert_spin_locked(&task_rq(p
)->lock
);
1113 if (unlikely(test_tsk_thread_flag(p
, tif_bit
)))
1116 set_tsk_thread_flag(p
, tif_bit
);
1119 if (cpu
== smp_processor_id())
1122 /* NEED_RESCHED must be visible before we test polling */
1124 if (!tsk_is_polling(p
))
1125 smp_send_reschedule(cpu
);
1128 static void resched_cpu(int cpu
)
1130 struct rq
*rq
= cpu_rq(cpu
);
1131 unsigned long flags
;
1133 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
1135 resched_task(cpu_curr(cpu
));
1136 spin_unlock_irqrestore(&rq
->lock
, flags
);
1141 * When add_timer_on() enqueues a timer into the timer wheel of an
1142 * idle CPU then this timer might expire before the next timer event
1143 * which is scheduled to wake up that CPU. In case of a completely
1144 * idle system the next event might even be infinite time into the
1145 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1146 * leaves the inner idle loop so the newly added timer is taken into
1147 * account when the CPU goes back to idle and evaluates the timer
1148 * wheel for the next timer event.
1150 void wake_up_idle_cpu(int cpu
)
1152 struct rq
*rq
= cpu_rq(cpu
);
1154 if (cpu
== smp_processor_id())
1158 * This is safe, as this function is called with the timer
1159 * wheel base lock of (cpu) held. When the CPU is on the way
1160 * to idle and has not yet set rq->curr to idle then it will
1161 * be serialized on the timer wheel base lock and take the new
1162 * timer into account automatically.
1164 if (rq
->curr
!= rq
->idle
)
1168 * We can set TIF_RESCHED on the idle task of the other CPU
1169 * lockless. The worst case is that the other CPU runs the
1170 * idle task through an additional NOOP schedule()
1172 set_tsk_thread_flag(rq
->idle
, TIF_NEED_RESCHED
);
1174 /* NEED_RESCHED must be visible before we test polling */
1176 if (!tsk_is_polling(rq
->idle
))
1177 smp_send_reschedule(cpu
);
1182 static void __resched_task(struct task_struct
*p
, int tif_bit
)
1184 assert_spin_locked(&task_rq(p
)->lock
);
1185 set_tsk_thread_flag(p
, tif_bit
);
1189 #if BITS_PER_LONG == 32
1190 # define WMULT_CONST (~0UL)
1192 # define WMULT_CONST (1UL << 32)
1195 #define WMULT_SHIFT 32
1198 * Shift right and round:
1200 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1202 static unsigned long
1203 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
1204 struct load_weight
*lw
)
1208 if (unlikely(!lw
->inv_weight
))
1209 lw
->inv_weight
= (WMULT_CONST
-lw
->weight
/2) / (lw
->weight
+1);
1211 tmp
= (u64
)delta_exec
* weight
;
1213 * Check whether we'd overflow the 64-bit multiplication:
1215 if (unlikely(tmp
> WMULT_CONST
))
1216 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
1219 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
1221 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
1224 static inline unsigned long
1225 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
1227 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
1230 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
1236 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
1243 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1244 * of tasks with abnormal "nice" values across CPUs the contribution that
1245 * each task makes to its run queue's load is weighted according to its
1246 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1247 * scaled version of the new time slice allocation that they receive on time
1251 #define WEIGHT_IDLEPRIO 2
1252 #define WMULT_IDLEPRIO (1 << 31)
1255 * Nice levels are multiplicative, with a gentle 10% change for every
1256 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1257 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1258 * that remained on nice 0.
1260 * The "10% effect" is relative and cumulative: from _any_ nice level,
1261 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1262 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1263 * If a task goes up by ~10% and another task goes down by ~10% then
1264 * the relative distance between them is ~25%.)
1266 static const int prio_to_weight
[40] = {
1267 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1268 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1269 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1270 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1271 /* 0 */ 1024, 820, 655, 526, 423,
1272 /* 5 */ 335, 272, 215, 172, 137,
1273 /* 10 */ 110, 87, 70, 56, 45,
1274 /* 15 */ 36, 29, 23, 18, 15,
1278 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1280 * In cases where the weight does not change often, we can use the
1281 * precalculated inverse to speed up arithmetics by turning divisions
1282 * into multiplications:
1284 static const u32 prio_to_wmult
[40] = {
1285 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1286 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1287 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1288 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1289 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1290 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1291 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1292 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1295 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
1298 * runqueue iterator, to support SMP load-balancing between different
1299 * scheduling classes, without having to expose their internal data
1300 * structures to the load-balancing proper:
1302 struct rq_iterator
{
1304 struct task_struct
*(*start
)(void *);
1305 struct task_struct
*(*next
)(void *);
1309 static unsigned long
1310 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1311 unsigned long max_load_move
, struct sched_domain
*sd
,
1312 enum cpu_idle_type idle
, int *all_pinned
,
1313 int *this_best_prio
, struct rq_iterator
*iterator
);
1316 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1317 struct sched_domain
*sd
, enum cpu_idle_type idle
,
1318 struct rq_iterator
*iterator
);
1321 #ifdef CONFIG_CGROUP_CPUACCT
1322 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
);
1324 static inline void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
) {}
1328 static unsigned long source_load(int cpu
, int type
);
1329 static unsigned long target_load(int cpu
, int type
);
1330 static unsigned long cpu_avg_load_per_task(int cpu
);
1331 static int task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
);
1332 #endif /* CONFIG_SMP */
1334 #include "sched_stats.h"
1335 #include "sched_idletask.c"
1336 #include "sched_fair.c"
1337 #include "sched_rt.c"
1338 #ifdef CONFIG_SCHED_DEBUG
1339 # include "sched_debug.c"
1342 #define sched_class_highest (&rt_sched_class)
1344 static inline void inc_load(struct rq
*rq
, const struct task_struct
*p
)
1346 update_load_add(&rq
->load
, p
->se
.load
.weight
);
1349 static inline void dec_load(struct rq
*rq
, const struct task_struct
*p
)
1351 update_load_sub(&rq
->load
, p
->se
.load
.weight
);
1354 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
1360 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
1366 static void set_load_weight(struct task_struct
*p
)
1368 if (task_has_rt_policy(p
)) {
1369 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
1370 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
1375 * SCHED_IDLE tasks get minimal weight:
1377 if (p
->policy
== SCHED_IDLE
) {
1378 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
1379 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
1383 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
1384 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
1387 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
1389 sched_info_queued(p
);
1390 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
1394 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1396 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
1401 * __normal_prio - return the priority that is based on the static prio
1403 static inline int __normal_prio(struct task_struct
*p
)
1405 return p
->static_prio
;
1409 * Calculate the expected normal priority: i.e. priority
1410 * without taking RT-inheritance into account. Might be
1411 * boosted by interactivity modifiers. Changes upon fork,
1412 * setprio syscalls, and whenever the interactivity
1413 * estimator recalculates.
1415 static inline int normal_prio(struct task_struct
*p
)
1419 if (task_has_rt_policy(p
))
1420 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
1422 prio
= __normal_prio(p
);
1427 * Calculate the current priority, i.e. the priority
1428 * taken into account by the scheduler. This value might
1429 * be boosted by RT tasks, or might be boosted by
1430 * interactivity modifiers. Will be RT if the task got
1431 * RT-boosted. If not then it returns p->normal_prio.
1433 static int effective_prio(struct task_struct
*p
)
1435 p
->normal_prio
= normal_prio(p
);
1437 * If we are RT tasks or we were boosted to RT priority,
1438 * keep the priority unchanged. Otherwise, update priority
1439 * to the normal priority:
1441 if (!rt_prio(p
->prio
))
1442 return p
->normal_prio
;
1447 * activate_task - move a task to the runqueue.
1449 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
1451 if (task_contributes_to_load(p
))
1452 rq
->nr_uninterruptible
--;
1454 enqueue_task(rq
, p
, wakeup
);
1455 inc_nr_running(p
, rq
);
1459 * deactivate_task - remove a task from the runqueue.
1461 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1463 if (task_contributes_to_load(p
))
1464 rq
->nr_uninterruptible
++;
1466 dequeue_task(rq
, p
, sleep
);
1467 dec_nr_running(p
, rq
);
1471 * task_curr - is this task currently executing on a CPU?
1472 * @p: the task in question.
1474 inline int task_curr(const struct task_struct
*p
)
1476 return cpu_curr(task_cpu(p
)) == p
;
1479 /* Used instead of source_load when we know the type == 0 */
1480 unsigned long weighted_cpuload(const int cpu
)
1482 return cpu_rq(cpu
)->load
.weight
;
1485 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
1487 set_task_rq(p
, cpu
);
1490 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1491 * successfuly executed on another CPU. We must ensure that updates of
1492 * per-task data have been completed by this moment.
1495 task_thread_info(p
)->cpu
= cpu
;
1499 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
1500 const struct sched_class
*prev_class
,
1501 int oldprio
, int running
)
1503 if (prev_class
!= p
->sched_class
) {
1504 if (prev_class
->switched_from
)
1505 prev_class
->switched_from(rq
, p
, running
);
1506 p
->sched_class
->switched_to(rq
, p
, running
);
1508 p
->sched_class
->prio_changed(rq
, p
, oldprio
, running
);
1514 * Is this task likely cache-hot:
1517 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
1522 * Buddy candidates are cache hot:
1524 if (sched_feat(CACHE_HOT_BUDDY
) && (&p
->se
== cfs_rq_of(&p
->se
)->next
))
1527 if (p
->sched_class
!= &fair_sched_class
)
1530 if (sysctl_sched_migration_cost
== -1)
1532 if (sysctl_sched_migration_cost
== 0)
1535 delta
= now
- p
->se
.exec_start
;
1537 return delta
< (s64
)sysctl_sched_migration_cost
;
1541 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1543 int old_cpu
= task_cpu(p
);
1544 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
1545 struct cfs_rq
*old_cfsrq
= task_cfs_rq(p
),
1546 *new_cfsrq
= cpu_cfs_rq(old_cfsrq
, new_cpu
);
1549 clock_offset
= old_rq
->clock
- new_rq
->clock
;
1551 #ifdef CONFIG_SCHEDSTATS
1552 if (p
->se
.wait_start
)
1553 p
->se
.wait_start
-= clock_offset
;
1554 if (p
->se
.sleep_start
)
1555 p
->se
.sleep_start
-= clock_offset
;
1556 if (p
->se
.block_start
)
1557 p
->se
.block_start
-= clock_offset
;
1558 if (old_cpu
!= new_cpu
) {
1559 schedstat_inc(p
, se
.nr_migrations
);
1560 if (task_hot(p
, old_rq
->clock
, NULL
))
1561 schedstat_inc(p
, se
.nr_forced2_migrations
);
1564 p
->se
.vruntime
-= old_cfsrq
->min_vruntime
-
1565 new_cfsrq
->min_vruntime
;
1567 __set_task_cpu(p
, new_cpu
);
1570 struct migration_req
{
1571 struct list_head list
;
1573 struct task_struct
*task
;
1576 struct completion done
;
1580 * The task's runqueue lock must be held.
1581 * Returns true if you have to wait for migration thread.
1584 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1586 struct rq
*rq
= task_rq(p
);
1589 * If the task is not on a runqueue (and not running), then
1590 * it is sufficient to simply update the task's cpu field.
1592 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1593 set_task_cpu(p
, dest_cpu
);
1597 init_completion(&req
->done
);
1599 req
->dest_cpu
= dest_cpu
;
1600 list_add(&req
->list
, &rq
->migration_queue
);
1606 * wait_task_inactive - wait for a thread to unschedule.
1608 * The caller must ensure that the task *will* unschedule sometime soon,
1609 * else this function might spin for a *long* time. This function can't
1610 * be called with interrupts off, or it may introduce deadlock with
1611 * smp_call_function() if an IPI is sent by the same process we are
1612 * waiting to become inactive.
1614 void wait_task_inactive(struct task_struct
*p
)
1616 unsigned long flags
;
1622 * We do the initial early heuristics without holding
1623 * any task-queue locks at all. We'll only try to get
1624 * the runqueue lock when things look like they will
1630 * If the task is actively running on another CPU
1631 * still, just relax and busy-wait without holding
1634 * NOTE! Since we don't hold any locks, it's not
1635 * even sure that "rq" stays as the right runqueue!
1636 * But we don't care, since "task_running()" will
1637 * return false if the runqueue has changed and p
1638 * is actually now running somewhere else!
1640 while (task_running(rq
, p
))
1644 * Ok, time to look more closely! We need the rq
1645 * lock now, to be *sure*. If we're wrong, we'll
1646 * just go back and repeat.
1648 rq
= task_rq_lock(p
, &flags
);
1649 running
= task_running(rq
, p
);
1650 on_rq
= p
->se
.on_rq
;
1651 task_rq_unlock(rq
, &flags
);
1654 * Was it really running after all now that we
1655 * checked with the proper locks actually held?
1657 * Oops. Go back and try again..
1659 if (unlikely(running
)) {
1665 * It's not enough that it's not actively running,
1666 * it must be off the runqueue _entirely_, and not
1669 * So if it wa still runnable (but just not actively
1670 * running right now), it's preempted, and we should
1671 * yield - it could be a while.
1673 if (unlikely(on_rq
)) {
1674 schedule_timeout_uninterruptible(1);
1679 * Ahh, all good. It wasn't running, and it wasn't
1680 * runnable, which means that it will never become
1681 * running in the future either. We're all done!
1688 * kick_process - kick a running thread to enter/exit the kernel
1689 * @p: the to-be-kicked thread
1691 * Cause a process which is running on another CPU to enter
1692 * kernel-mode, without any delay. (to get signals handled.)
1694 * NOTE: this function doesnt have to take the runqueue lock,
1695 * because all it wants to ensure is that the remote task enters
1696 * the kernel. If the IPI races and the task has been migrated
1697 * to another CPU then no harm is done and the purpose has been
1700 void kick_process(struct task_struct
*p
)
1706 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1707 smp_send_reschedule(cpu
);
1712 * Return a low guess at the load of a migration-source cpu weighted
1713 * according to the scheduling class and "nice" value.
1715 * We want to under-estimate the load of migration sources, to
1716 * balance conservatively.
1718 static unsigned long source_load(int cpu
, int type
)
1720 struct rq
*rq
= cpu_rq(cpu
);
1721 unsigned long total
= weighted_cpuload(cpu
);
1726 return min(rq
->cpu_load
[type
-1], total
);
1730 * Return a high guess at the load of a migration-target cpu weighted
1731 * according to the scheduling class and "nice" value.
1733 static unsigned long target_load(int cpu
, int type
)
1735 struct rq
*rq
= cpu_rq(cpu
);
1736 unsigned long total
= weighted_cpuload(cpu
);
1741 return max(rq
->cpu_load
[type
-1], total
);
1745 * Return the average load per task on the cpu's run queue
1747 static unsigned long cpu_avg_load_per_task(int cpu
)
1749 struct rq
*rq
= cpu_rq(cpu
);
1750 unsigned long total
= weighted_cpuload(cpu
);
1751 unsigned long n
= rq
->nr_running
;
1753 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1757 * find_idlest_group finds and returns the least busy CPU group within the
1760 static struct sched_group
*
1761 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1763 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1764 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1765 int load_idx
= sd
->forkexec_idx
;
1766 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1769 unsigned long load
, avg_load
;
1773 /* Skip over this group if it has no CPUs allowed */
1774 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1777 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1779 /* Tally up the load of all CPUs in the group */
1782 for_each_cpu_mask(i
, group
->cpumask
) {
1783 /* Bias balancing toward cpus of our domain */
1785 load
= source_load(i
, load_idx
);
1787 load
= target_load(i
, load_idx
);
1792 /* Adjust by relative CPU power of the group */
1793 avg_load
= sg_div_cpu_power(group
,
1794 avg_load
* SCHED_LOAD_SCALE
);
1797 this_load
= avg_load
;
1799 } else if (avg_load
< min_load
) {
1800 min_load
= avg_load
;
1803 } while (group
= group
->next
, group
!= sd
->groups
);
1805 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1811 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1814 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1817 unsigned long load
, min_load
= ULONG_MAX
;
1821 /* Traverse only the allowed CPUs */
1822 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1824 for_each_cpu_mask(i
, tmp
) {
1825 load
= weighted_cpuload(i
);
1827 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1837 * sched_balance_self: balance the current task (running on cpu) in domains
1838 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1841 * Balance, ie. select the least loaded group.
1843 * Returns the target CPU number, or the same CPU if no balancing is needed.
1845 * preempt must be disabled.
1847 static int sched_balance_self(int cpu
, int flag
)
1849 struct task_struct
*t
= current
;
1850 struct sched_domain
*tmp
, *sd
= NULL
;
1852 for_each_domain(cpu
, tmp
) {
1854 * If power savings logic is enabled for a domain, stop there.
1856 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1858 if (tmp
->flags
& flag
)
1864 struct sched_group
*group
;
1865 int new_cpu
, weight
;
1867 if (!(sd
->flags
& flag
)) {
1873 group
= find_idlest_group(sd
, t
, cpu
);
1879 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1880 if (new_cpu
== -1 || new_cpu
== cpu
) {
1881 /* Now try balancing at a lower domain level of cpu */
1886 /* Now try balancing at a lower domain level of new_cpu */
1889 weight
= cpus_weight(span
);
1890 for_each_domain(cpu
, tmp
) {
1891 if (weight
<= cpus_weight(tmp
->span
))
1893 if (tmp
->flags
& flag
)
1896 /* while loop will break here if sd == NULL */
1902 #endif /* CONFIG_SMP */
1905 * try_to_wake_up - wake up a thread
1906 * @p: the to-be-woken-up thread
1907 * @state: the mask of task states that can be woken
1908 * @sync: do a synchronous wakeup?
1910 * Put it on the run-queue if it's not already there. The "current"
1911 * thread is always on the run-queue (except when the actual
1912 * re-schedule is in progress), and as such you're allowed to do
1913 * the simpler "current->state = TASK_RUNNING" to mark yourself
1914 * runnable without the overhead of this.
1916 * returns failure only if the task is already active.
1918 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1920 int cpu
, orig_cpu
, this_cpu
, success
= 0;
1921 unsigned long flags
;
1925 if (!sched_feat(SYNC_WAKEUPS
))
1929 rq
= task_rq_lock(p
, &flags
);
1930 old_state
= p
->state
;
1931 if (!(old_state
& state
))
1939 this_cpu
= smp_processor_id();
1942 if (unlikely(task_running(rq
, p
)))
1945 cpu
= p
->sched_class
->select_task_rq(p
, sync
);
1946 if (cpu
!= orig_cpu
) {
1947 set_task_cpu(p
, cpu
);
1948 task_rq_unlock(rq
, &flags
);
1949 /* might preempt at this point */
1950 rq
= task_rq_lock(p
, &flags
);
1951 old_state
= p
->state
;
1952 if (!(old_state
& state
))
1957 this_cpu
= smp_processor_id();
1961 #ifdef CONFIG_SCHEDSTATS
1962 schedstat_inc(rq
, ttwu_count
);
1963 if (cpu
== this_cpu
)
1964 schedstat_inc(rq
, ttwu_local
);
1966 struct sched_domain
*sd
;
1967 for_each_domain(this_cpu
, sd
) {
1968 if (cpu_isset(cpu
, sd
->span
)) {
1969 schedstat_inc(sd
, ttwu_wake_remote
);
1977 #endif /* CONFIG_SMP */
1978 schedstat_inc(p
, se
.nr_wakeups
);
1980 schedstat_inc(p
, se
.nr_wakeups_sync
);
1981 if (orig_cpu
!= cpu
)
1982 schedstat_inc(p
, se
.nr_wakeups_migrate
);
1983 if (cpu
== this_cpu
)
1984 schedstat_inc(p
, se
.nr_wakeups_local
);
1986 schedstat_inc(p
, se
.nr_wakeups_remote
);
1987 update_rq_clock(rq
);
1988 activate_task(rq
, p
, 1);
1992 check_preempt_curr(rq
, p
);
1994 p
->state
= TASK_RUNNING
;
1996 if (p
->sched_class
->task_wake_up
)
1997 p
->sched_class
->task_wake_up(rq
, p
);
2000 task_rq_unlock(rq
, &flags
);
2005 int wake_up_process(struct task_struct
*p
)
2007 return try_to_wake_up(p
, TASK_ALL
, 0);
2009 EXPORT_SYMBOL(wake_up_process
);
2011 int wake_up_state(struct task_struct
*p
, unsigned int state
)
2013 return try_to_wake_up(p
, state
, 0);
2017 * Perform scheduler related setup for a newly forked process p.
2018 * p is forked by current.
2020 * __sched_fork() is basic setup used by init_idle() too:
2022 static void __sched_fork(struct task_struct
*p
)
2024 p
->se
.exec_start
= 0;
2025 p
->se
.sum_exec_runtime
= 0;
2026 p
->se
.prev_sum_exec_runtime
= 0;
2027 p
->se
.last_wakeup
= 0;
2028 p
->se
.avg_overlap
= 0;
2030 #ifdef CONFIG_SCHEDSTATS
2031 p
->se
.wait_start
= 0;
2032 p
->se
.sum_sleep_runtime
= 0;
2033 p
->se
.sleep_start
= 0;
2034 p
->se
.block_start
= 0;
2035 p
->se
.sleep_max
= 0;
2036 p
->se
.block_max
= 0;
2038 p
->se
.slice_max
= 0;
2042 INIT_LIST_HEAD(&p
->rt
.run_list
);
2045 #ifdef CONFIG_PREEMPT_NOTIFIERS
2046 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
2050 * We mark the process as running here, but have not actually
2051 * inserted it onto the runqueue yet. This guarantees that
2052 * nobody will actually run it, and a signal or other external
2053 * event cannot wake it up and insert it on the runqueue either.
2055 p
->state
= TASK_RUNNING
;
2059 * fork()/clone()-time setup:
2061 void sched_fork(struct task_struct
*p
, int clone_flags
)
2063 int cpu
= get_cpu();
2068 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
2070 set_task_cpu(p
, cpu
);
2073 * Make sure we do not leak PI boosting priority to the child:
2075 p
->prio
= current
->normal_prio
;
2076 if (!rt_prio(p
->prio
))
2077 p
->sched_class
= &fair_sched_class
;
2079 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2080 if (likely(sched_info_on()))
2081 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
2083 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
2086 #ifdef CONFIG_PREEMPT
2087 /* Want to start with kernel preemption disabled. */
2088 task_thread_info(p
)->preempt_count
= 1;
2094 * wake_up_new_task - wake up a newly created task for the first time.
2096 * This function will do some initial scheduler statistics housekeeping
2097 * that must be done for every newly created context, then puts the task
2098 * on the runqueue and wakes it.
2100 void wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
2102 unsigned long flags
;
2105 rq
= task_rq_lock(p
, &flags
);
2106 BUG_ON(p
->state
!= TASK_RUNNING
);
2107 update_rq_clock(rq
);
2109 p
->prio
= effective_prio(p
);
2111 if (!p
->sched_class
->task_new
|| !current
->se
.on_rq
) {
2112 activate_task(rq
, p
, 0);
2115 * Let the scheduling class do new task startup
2116 * management (if any):
2118 p
->sched_class
->task_new(rq
, p
);
2119 inc_nr_running(p
, rq
);
2121 check_preempt_curr(rq
, p
);
2123 if (p
->sched_class
->task_wake_up
)
2124 p
->sched_class
->task_wake_up(rq
, p
);
2126 task_rq_unlock(rq
, &flags
);
2129 #ifdef CONFIG_PREEMPT_NOTIFIERS
2132 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
2133 * @notifier: notifier struct to register
2135 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2137 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2139 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2142 * preempt_notifier_unregister - no longer interested in preemption notifications
2143 * @notifier: notifier struct to unregister
2145 * This is safe to call from within a preemption notifier.
2147 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2149 hlist_del(¬ifier
->link
);
2151 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2153 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2155 struct preempt_notifier
*notifier
;
2156 struct hlist_node
*node
;
2158 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2159 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2163 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2164 struct task_struct
*next
)
2166 struct preempt_notifier
*notifier
;
2167 struct hlist_node
*node
;
2169 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2170 notifier
->ops
->sched_out(notifier
, next
);
2175 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2180 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2181 struct task_struct
*next
)
2188 * prepare_task_switch - prepare to switch tasks
2189 * @rq: the runqueue preparing to switch
2190 * @prev: the current task that is being switched out
2191 * @next: the task we are going to switch to.
2193 * This is called with the rq lock held and interrupts off. It must
2194 * be paired with a subsequent finish_task_switch after the context
2197 * prepare_task_switch sets up locking and calls architecture specific
2201 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
2202 struct task_struct
*next
)
2204 fire_sched_out_preempt_notifiers(prev
, next
);
2205 prepare_lock_switch(rq
, next
);
2206 prepare_arch_switch(next
);
2210 * finish_task_switch - clean up after a task-switch
2211 * @rq: runqueue associated with task-switch
2212 * @prev: the thread we just switched away from.
2214 * finish_task_switch must be called after the context switch, paired
2215 * with a prepare_task_switch call before the context switch.
2216 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2217 * and do any other architecture-specific cleanup actions.
2219 * Note that we may have delayed dropping an mm in context_switch(). If
2220 * so, we finish that here outside of the runqueue lock. (Doing it
2221 * with the lock held can cause deadlocks; see schedule() for
2224 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
2225 __releases(rq
->lock
)
2227 struct mm_struct
*mm
= rq
->prev_mm
;
2233 * A task struct has one reference for the use as "current".
2234 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2235 * schedule one last time. The schedule call will never return, and
2236 * the scheduled task must drop that reference.
2237 * The test for TASK_DEAD must occur while the runqueue locks are
2238 * still held, otherwise prev could be scheduled on another cpu, die
2239 * there before we look at prev->state, and then the reference would
2241 * Manfred Spraul <manfred@colorfullife.com>
2243 prev_state
= prev
->state
;
2244 finish_arch_switch(prev
);
2245 finish_lock_switch(rq
, prev
);
2247 if (current
->sched_class
->post_schedule
)
2248 current
->sched_class
->post_schedule(rq
);
2251 fire_sched_in_preempt_notifiers(current
);
2254 if (unlikely(prev_state
== TASK_DEAD
)) {
2256 * Remove function-return probe instances associated with this
2257 * task and put them back on the free list.
2259 kprobe_flush_task(prev
);
2260 put_task_struct(prev
);
2265 * schedule_tail - first thing a freshly forked thread must call.
2266 * @prev: the thread we just switched away from.
2268 asmlinkage
void schedule_tail(struct task_struct
*prev
)
2269 __releases(rq
->lock
)
2271 struct rq
*rq
= this_rq();
2273 finish_task_switch(rq
, prev
);
2274 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2275 /* In this case, finish_task_switch does not reenable preemption */
2278 if (current
->set_child_tid
)
2279 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2283 * context_switch - switch to the new MM and the new
2284 * thread's register state.
2287 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2288 struct task_struct
*next
)
2290 struct mm_struct
*mm
, *oldmm
;
2292 prepare_task_switch(rq
, prev
, next
);
2294 oldmm
= prev
->active_mm
;
2296 * For paravirt, this is coupled with an exit in switch_to to
2297 * combine the page table reload and the switch backend into
2300 arch_enter_lazy_cpu_mode();
2302 if (unlikely(!mm
)) {
2303 next
->active_mm
= oldmm
;
2304 atomic_inc(&oldmm
->mm_count
);
2305 enter_lazy_tlb(oldmm
, next
);
2307 switch_mm(oldmm
, mm
, next
);
2309 if (unlikely(!prev
->mm
)) {
2310 prev
->active_mm
= NULL
;
2311 rq
->prev_mm
= oldmm
;
2314 * Since the runqueue lock will be released by the next
2315 * task (which is an invalid locking op but in the case
2316 * of the scheduler it's an obvious special-case), so we
2317 * do an early lockdep release here:
2319 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2320 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2323 /* Here we just switch the register state and the stack. */
2324 switch_to(prev
, next
, prev
);
2328 * this_rq must be evaluated again because prev may have moved
2329 * CPUs since it called schedule(), thus the 'rq' on its stack
2330 * frame will be invalid.
2332 finish_task_switch(this_rq(), prev
);
2336 * nr_running, nr_uninterruptible and nr_context_switches:
2338 * externally visible scheduler statistics: current number of runnable
2339 * threads, current number of uninterruptible-sleeping threads, total
2340 * number of context switches performed since bootup.
2342 unsigned long nr_running(void)
2344 unsigned long i
, sum
= 0;
2346 for_each_online_cpu(i
)
2347 sum
+= cpu_rq(i
)->nr_running
;
2352 unsigned long nr_uninterruptible(void)
2354 unsigned long i
, sum
= 0;
2356 for_each_possible_cpu(i
)
2357 sum
+= cpu_rq(i
)->nr_uninterruptible
;
2360 * Since we read the counters lockless, it might be slightly
2361 * inaccurate. Do not allow it to go below zero though:
2363 if (unlikely((long)sum
< 0))
2369 unsigned long long nr_context_switches(void)
2372 unsigned long long sum
= 0;
2374 for_each_possible_cpu(i
)
2375 sum
+= cpu_rq(i
)->nr_switches
;
2380 unsigned long nr_iowait(void)
2382 unsigned long i
, sum
= 0;
2384 for_each_possible_cpu(i
)
2385 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2390 unsigned long nr_active(void)
2392 unsigned long i
, running
= 0, uninterruptible
= 0;
2394 for_each_online_cpu(i
) {
2395 running
+= cpu_rq(i
)->nr_running
;
2396 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
2399 if (unlikely((long)uninterruptible
< 0))
2400 uninterruptible
= 0;
2402 return running
+ uninterruptible
;
2406 * Update rq->cpu_load[] statistics. This function is usually called every
2407 * scheduler tick (TICK_NSEC).
2409 static void update_cpu_load(struct rq
*this_rq
)
2411 unsigned long this_load
= this_rq
->load
.weight
;
2414 this_rq
->nr_load_updates
++;
2416 /* Update our load: */
2417 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2418 unsigned long old_load
, new_load
;
2420 /* scale is effectively 1 << i now, and >> i divides by scale */
2422 old_load
= this_rq
->cpu_load
[i
];
2423 new_load
= this_load
;
2425 * Round up the averaging division if load is increasing. This
2426 * prevents us from getting stuck on 9 if the load is 10, for
2429 if (new_load
> old_load
)
2430 new_load
+= scale
-1;
2431 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2438 * double_rq_lock - safely lock two runqueues
2440 * Note this does not disable interrupts like task_rq_lock,
2441 * you need to do so manually before calling.
2443 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
2444 __acquires(rq1
->lock
)
2445 __acquires(rq2
->lock
)
2447 BUG_ON(!irqs_disabled());
2449 spin_lock(&rq1
->lock
);
2450 __acquire(rq2
->lock
); /* Fake it out ;) */
2453 spin_lock(&rq1
->lock
);
2454 spin_lock(&rq2
->lock
);
2456 spin_lock(&rq2
->lock
);
2457 spin_lock(&rq1
->lock
);
2460 update_rq_clock(rq1
);
2461 update_rq_clock(rq2
);
2465 * double_rq_unlock - safely unlock two runqueues
2467 * Note this does not restore interrupts like task_rq_unlock,
2468 * you need to do so manually after calling.
2470 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2471 __releases(rq1
->lock
)
2472 __releases(rq2
->lock
)
2474 spin_unlock(&rq1
->lock
);
2476 spin_unlock(&rq2
->lock
);
2478 __release(rq2
->lock
);
2482 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2484 static int double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2485 __releases(this_rq
->lock
)
2486 __acquires(busiest
->lock
)
2487 __acquires(this_rq
->lock
)
2491 if (unlikely(!irqs_disabled())) {
2492 /* printk() doesn't work good under rq->lock */
2493 spin_unlock(&this_rq
->lock
);
2496 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2497 if (busiest
< this_rq
) {
2498 spin_unlock(&this_rq
->lock
);
2499 spin_lock(&busiest
->lock
);
2500 spin_lock(&this_rq
->lock
);
2503 spin_lock(&busiest
->lock
);
2509 * If dest_cpu is allowed for this process, migrate the task to it.
2510 * This is accomplished by forcing the cpu_allowed mask to only
2511 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2512 * the cpu_allowed mask is restored.
2514 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2516 struct migration_req req
;
2517 unsigned long flags
;
2520 rq
= task_rq_lock(p
, &flags
);
2521 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2522 || unlikely(cpu_is_offline(dest_cpu
)))
2525 /* force the process onto the specified CPU */
2526 if (migrate_task(p
, dest_cpu
, &req
)) {
2527 /* Need to wait for migration thread (might exit: take ref). */
2528 struct task_struct
*mt
= rq
->migration_thread
;
2530 get_task_struct(mt
);
2531 task_rq_unlock(rq
, &flags
);
2532 wake_up_process(mt
);
2533 put_task_struct(mt
);
2534 wait_for_completion(&req
.done
);
2539 task_rq_unlock(rq
, &flags
);
2543 * sched_exec - execve() is a valuable balancing opportunity, because at
2544 * this point the task has the smallest effective memory and cache footprint.
2546 void sched_exec(void)
2548 int new_cpu
, this_cpu
= get_cpu();
2549 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2551 if (new_cpu
!= this_cpu
)
2552 sched_migrate_task(current
, new_cpu
);
2556 * pull_task - move a task from a remote runqueue to the local runqueue.
2557 * Both runqueues must be locked.
2559 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2560 struct rq
*this_rq
, int this_cpu
)
2562 deactivate_task(src_rq
, p
, 0);
2563 set_task_cpu(p
, this_cpu
);
2564 activate_task(this_rq
, p
, 0);
2566 * Note that idle threads have a prio of MAX_PRIO, for this test
2567 * to be always true for them.
2569 check_preempt_curr(this_rq
, p
);
2573 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2576 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2577 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2581 * We do not migrate tasks that are:
2582 * 1) running (obviously), or
2583 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2584 * 3) are cache-hot on their current CPU.
2586 if (!cpu_isset(this_cpu
, p
->cpus_allowed
)) {
2587 schedstat_inc(p
, se
.nr_failed_migrations_affine
);
2592 if (task_running(rq
, p
)) {
2593 schedstat_inc(p
, se
.nr_failed_migrations_running
);
2598 * Aggressive migration if:
2599 * 1) task is cache cold, or
2600 * 2) too many balance attempts have failed.
2603 if (!task_hot(p
, rq
->clock
, sd
) ||
2604 sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2605 #ifdef CONFIG_SCHEDSTATS
2606 if (task_hot(p
, rq
->clock
, sd
)) {
2607 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2608 schedstat_inc(p
, se
.nr_forced_migrations
);
2614 if (task_hot(p
, rq
->clock
, sd
)) {
2615 schedstat_inc(p
, se
.nr_failed_migrations_hot
);
2621 static unsigned long
2622 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2623 unsigned long max_load_move
, struct sched_domain
*sd
,
2624 enum cpu_idle_type idle
, int *all_pinned
,
2625 int *this_best_prio
, struct rq_iterator
*iterator
)
2627 int loops
= 0, pulled
= 0, pinned
= 0, skip_for_load
;
2628 struct task_struct
*p
;
2629 long rem_load_move
= max_load_move
;
2631 if (max_load_move
== 0)
2637 * Start the load-balancing iterator:
2639 p
= iterator
->start(iterator
->arg
);
2641 if (!p
|| loops
++ > sysctl_sched_nr_migrate
)
2644 * To help distribute high priority tasks across CPUs we don't
2645 * skip a task if it will be the highest priority task (i.e. smallest
2646 * prio value) on its new queue regardless of its load weight
2648 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2649 SCHED_LOAD_SCALE_FUZZ
;
2650 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2651 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2652 p
= iterator
->next(iterator
->arg
);
2656 pull_task(busiest
, p
, this_rq
, this_cpu
);
2658 rem_load_move
-= p
->se
.load
.weight
;
2661 * We only want to steal up to the prescribed amount of weighted load.
2663 if (rem_load_move
> 0) {
2664 if (p
->prio
< *this_best_prio
)
2665 *this_best_prio
= p
->prio
;
2666 p
= iterator
->next(iterator
->arg
);
2671 * Right now, this is one of only two places pull_task() is called,
2672 * so we can safely collect pull_task() stats here rather than
2673 * inside pull_task().
2675 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2678 *all_pinned
= pinned
;
2680 return max_load_move
- rem_load_move
;
2684 * move_tasks tries to move up to max_load_move weighted load from busiest to
2685 * this_rq, as part of a balancing operation within domain "sd".
2686 * Returns 1 if successful and 0 otherwise.
2688 * Called with both runqueues locked.
2690 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2691 unsigned long max_load_move
,
2692 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2695 const struct sched_class
*class = sched_class_highest
;
2696 unsigned long total_load_moved
= 0;
2697 int this_best_prio
= this_rq
->curr
->prio
;
2701 class->load_balance(this_rq
, this_cpu
, busiest
,
2702 max_load_move
- total_load_moved
,
2703 sd
, idle
, all_pinned
, &this_best_prio
);
2704 class = class->next
;
2705 } while (class && max_load_move
> total_load_moved
);
2707 return total_load_moved
> 0;
2711 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2712 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2713 struct rq_iterator
*iterator
)
2715 struct task_struct
*p
= iterator
->start(iterator
->arg
);
2719 if (can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2720 pull_task(busiest
, p
, this_rq
, this_cpu
);
2722 * Right now, this is only the second place pull_task()
2723 * is called, so we can safely collect pull_task()
2724 * stats here rather than inside pull_task().
2726 schedstat_inc(sd
, lb_gained
[idle
]);
2730 p
= iterator
->next(iterator
->arg
);
2737 * move_one_task tries to move exactly one task from busiest to this_rq, as
2738 * part of active balancing operations within "domain".
2739 * Returns 1 if successful and 0 otherwise.
2741 * Called with both runqueues locked.
2743 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2744 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2746 const struct sched_class
*class;
2748 for (class = sched_class_highest
; class; class = class->next
)
2749 if (class->move_one_task(this_rq
, this_cpu
, busiest
, sd
, idle
))
2756 * find_busiest_group finds and returns the busiest CPU group within the
2757 * domain. It calculates and returns the amount of weighted load which
2758 * should be moved to restore balance via the imbalance parameter.
2760 static struct sched_group
*
2761 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2762 unsigned long *imbalance
, enum cpu_idle_type idle
,
2763 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2765 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2766 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2767 unsigned long max_pull
;
2768 unsigned long busiest_load_per_task
, busiest_nr_running
;
2769 unsigned long this_load_per_task
, this_nr_running
;
2770 int load_idx
, group_imb
= 0;
2771 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2772 int power_savings_balance
= 1;
2773 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2774 unsigned long min_nr_running
= ULONG_MAX
;
2775 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2778 max_load
= this_load
= total_load
= total_pwr
= 0;
2779 busiest_load_per_task
= busiest_nr_running
= 0;
2780 this_load_per_task
= this_nr_running
= 0;
2781 if (idle
== CPU_NOT_IDLE
)
2782 load_idx
= sd
->busy_idx
;
2783 else if (idle
== CPU_NEWLY_IDLE
)
2784 load_idx
= sd
->newidle_idx
;
2786 load_idx
= sd
->idle_idx
;
2789 unsigned long load
, group_capacity
, max_cpu_load
, min_cpu_load
;
2792 int __group_imb
= 0;
2793 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2794 unsigned long sum_nr_running
, sum_weighted_load
;
2796 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2799 balance_cpu
= first_cpu(group
->cpumask
);
2801 /* Tally up the load of all CPUs in the group */
2802 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2804 min_cpu_load
= ~0UL;
2806 for_each_cpu_mask(i
, group
->cpumask
) {
2809 if (!cpu_isset(i
, *cpus
))
2814 if (*sd_idle
&& rq
->nr_running
)
2817 /* Bias balancing toward cpus of our domain */
2819 if (idle_cpu(i
) && !first_idle_cpu
) {
2824 load
= target_load(i
, load_idx
);
2826 load
= source_load(i
, load_idx
);
2827 if (load
> max_cpu_load
)
2828 max_cpu_load
= load
;
2829 if (min_cpu_load
> load
)
2830 min_cpu_load
= load
;
2834 sum_nr_running
+= rq
->nr_running
;
2835 sum_weighted_load
+= weighted_cpuload(i
);
2839 * First idle cpu or the first cpu(busiest) in this sched group
2840 * is eligible for doing load balancing at this and above
2841 * domains. In the newly idle case, we will allow all the cpu's
2842 * to do the newly idle load balance.
2844 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2845 balance_cpu
!= this_cpu
&& balance
) {
2850 total_load
+= avg_load
;
2851 total_pwr
+= group
->__cpu_power
;
2853 /* Adjust by relative CPU power of the group */
2854 avg_load
= sg_div_cpu_power(group
,
2855 avg_load
* SCHED_LOAD_SCALE
);
2857 if ((max_cpu_load
- min_cpu_load
) > SCHED_LOAD_SCALE
)
2860 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2863 this_load
= avg_load
;
2865 this_nr_running
= sum_nr_running
;
2866 this_load_per_task
= sum_weighted_load
;
2867 } else if (avg_load
> max_load
&&
2868 (sum_nr_running
> group_capacity
|| __group_imb
)) {
2869 max_load
= avg_load
;
2871 busiest_nr_running
= sum_nr_running
;
2872 busiest_load_per_task
= sum_weighted_load
;
2873 group_imb
= __group_imb
;
2876 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2878 * Busy processors will not participate in power savings
2881 if (idle
== CPU_NOT_IDLE
||
2882 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2886 * If the local group is idle or completely loaded
2887 * no need to do power savings balance at this domain
2889 if (local_group
&& (this_nr_running
>= group_capacity
||
2891 power_savings_balance
= 0;
2894 * If a group is already running at full capacity or idle,
2895 * don't include that group in power savings calculations
2897 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2902 * Calculate the group which has the least non-idle load.
2903 * This is the group from where we need to pick up the load
2906 if ((sum_nr_running
< min_nr_running
) ||
2907 (sum_nr_running
== min_nr_running
&&
2908 first_cpu(group
->cpumask
) <
2909 first_cpu(group_min
->cpumask
))) {
2911 min_nr_running
= sum_nr_running
;
2912 min_load_per_task
= sum_weighted_load
/
2917 * Calculate the group which is almost near its
2918 * capacity but still has some space to pick up some load
2919 * from other group and save more power
2921 if (sum_nr_running
<= group_capacity
- 1) {
2922 if (sum_nr_running
> leader_nr_running
||
2923 (sum_nr_running
== leader_nr_running
&&
2924 first_cpu(group
->cpumask
) >
2925 first_cpu(group_leader
->cpumask
))) {
2926 group_leader
= group
;
2927 leader_nr_running
= sum_nr_running
;
2932 group
= group
->next
;
2933 } while (group
!= sd
->groups
);
2935 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2938 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2940 if (this_load
>= avg_load
||
2941 100*max_load
<= sd
->imbalance_pct
*this_load
)
2944 busiest_load_per_task
/= busiest_nr_running
;
2946 busiest_load_per_task
= min(busiest_load_per_task
, avg_load
);
2949 * We're trying to get all the cpus to the average_load, so we don't
2950 * want to push ourselves above the average load, nor do we wish to
2951 * reduce the max loaded cpu below the average load, as either of these
2952 * actions would just result in more rebalancing later, and ping-pong
2953 * tasks around. Thus we look for the minimum possible imbalance.
2954 * Negative imbalances (*we* are more loaded than anyone else) will
2955 * be counted as no imbalance for these purposes -- we can't fix that
2956 * by pulling tasks to us. Be careful of negative numbers as they'll
2957 * appear as very large values with unsigned longs.
2959 if (max_load
<= busiest_load_per_task
)
2963 * In the presence of smp nice balancing, certain scenarios can have
2964 * max load less than avg load(as we skip the groups at or below
2965 * its cpu_power, while calculating max_load..)
2967 if (max_load
< avg_load
) {
2969 goto small_imbalance
;
2972 /* Don't want to pull so many tasks that a group would go idle */
2973 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2975 /* How much load to actually move to equalise the imbalance */
2976 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2977 (avg_load
- this_load
) * this->__cpu_power
)
2981 * if *imbalance is less than the average load per runnable task
2982 * there is no gaurantee that any tasks will be moved so we'll have
2983 * a think about bumping its value to force at least one task to be
2986 if (*imbalance
< busiest_load_per_task
) {
2987 unsigned long tmp
, pwr_now
, pwr_move
;
2991 pwr_move
= pwr_now
= 0;
2993 if (this_nr_running
) {
2994 this_load_per_task
/= this_nr_running
;
2995 if (busiest_load_per_task
> this_load_per_task
)
2998 this_load_per_task
= SCHED_LOAD_SCALE
;
3000 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
3001 busiest_load_per_task
* imbn
) {
3002 *imbalance
= busiest_load_per_task
;
3007 * OK, we don't have enough imbalance to justify moving tasks,
3008 * however we may be able to increase total CPU power used by
3012 pwr_now
+= busiest
->__cpu_power
*
3013 min(busiest_load_per_task
, max_load
);
3014 pwr_now
+= this->__cpu_power
*
3015 min(this_load_per_task
, this_load
);
3016 pwr_now
/= SCHED_LOAD_SCALE
;
3018 /* Amount of load we'd subtract */
3019 tmp
= sg_div_cpu_power(busiest
,
3020 busiest_load_per_task
* SCHED_LOAD_SCALE
);
3022 pwr_move
+= busiest
->__cpu_power
*
3023 min(busiest_load_per_task
, max_load
- tmp
);
3025 /* Amount of load we'd add */
3026 if (max_load
* busiest
->__cpu_power
<
3027 busiest_load_per_task
* SCHED_LOAD_SCALE
)
3028 tmp
= sg_div_cpu_power(this,
3029 max_load
* busiest
->__cpu_power
);
3031 tmp
= sg_div_cpu_power(this,
3032 busiest_load_per_task
* SCHED_LOAD_SCALE
);
3033 pwr_move
+= this->__cpu_power
*
3034 min(this_load_per_task
, this_load
+ tmp
);
3035 pwr_move
/= SCHED_LOAD_SCALE
;
3037 /* Move if we gain throughput */
3038 if (pwr_move
> pwr_now
)
3039 *imbalance
= busiest_load_per_task
;
3045 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3046 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
3049 if (this == group_leader
&& group_leader
!= group_min
) {
3050 *imbalance
= min_load_per_task
;
3060 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3063 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
3064 unsigned long imbalance
, cpumask_t
*cpus
)
3066 struct rq
*busiest
= NULL
, *rq
;
3067 unsigned long max_load
= 0;
3070 for_each_cpu_mask(i
, group
->cpumask
) {
3073 if (!cpu_isset(i
, *cpus
))
3077 wl
= weighted_cpuload(i
);
3079 if (rq
->nr_running
== 1 && wl
> imbalance
)
3082 if (wl
> max_load
) {
3092 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
3093 * so long as it is large enough.
3095 #define MAX_PINNED_INTERVAL 512
3098 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3099 * tasks if there is an imbalance.
3101 static int load_balance(int this_cpu
, struct rq
*this_rq
,
3102 struct sched_domain
*sd
, enum cpu_idle_type idle
,
3105 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
3106 struct sched_group
*group
;
3107 unsigned long imbalance
;
3109 cpumask_t cpus
= CPU_MASK_ALL
;
3110 unsigned long flags
;
3113 * When power savings policy is enabled for the parent domain, idle
3114 * sibling can pick up load irrespective of busy siblings. In this case,
3115 * let the state of idle sibling percolate up as CPU_IDLE, instead of
3116 * portraying it as CPU_NOT_IDLE.
3118 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3119 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3122 schedstat_inc(sd
, lb_count
[idle
]);
3125 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
3132 schedstat_inc(sd
, lb_nobusyg
[idle
]);
3136 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
3138 schedstat_inc(sd
, lb_nobusyq
[idle
]);
3142 BUG_ON(busiest
== this_rq
);
3144 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
3147 if (busiest
->nr_running
> 1) {
3149 * Attempt to move tasks. If find_busiest_group has found
3150 * an imbalance but busiest->nr_running <= 1, the group is
3151 * still unbalanced. ld_moved simply stays zero, so it is
3152 * correctly treated as an imbalance.
3154 local_irq_save(flags
);
3155 double_rq_lock(this_rq
, busiest
);
3156 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
3157 imbalance
, sd
, idle
, &all_pinned
);
3158 double_rq_unlock(this_rq
, busiest
);
3159 local_irq_restore(flags
);
3162 * some other cpu did the load balance for us.
3164 if (ld_moved
&& this_cpu
!= smp_processor_id())
3165 resched_cpu(this_cpu
);
3167 /* All tasks on this runqueue were pinned by CPU affinity */
3168 if (unlikely(all_pinned
)) {
3169 cpu_clear(cpu_of(busiest
), cpus
);
3170 if (!cpus_empty(cpus
))
3177 schedstat_inc(sd
, lb_failed
[idle
]);
3178 sd
->nr_balance_failed
++;
3180 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
3182 spin_lock_irqsave(&busiest
->lock
, flags
);
3184 /* don't kick the migration_thread, if the curr
3185 * task on busiest cpu can't be moved to this_cpu
3187 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
3188 spin_unlock_irqrestore(&busiest
->lock
, flags
);
3190 goto out_one_pinned
;
3193 if (!busiest
->active_balance
) {
3194 busiest
->active_balance
= 1;
3195 busiest
->push_cpu
= this_cpu
;
3198 spin_unlock_irqrestore(&busiest
->lock
, flags
);
3200 wake_up_process(busiest
->migration_thread
);
3203 * We've kicked active balancing, reset the failure
3206 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
3209 sd
->nr_balance_failed
= 0;
3211 if (likely(!active_balance
)) {
3212 /* We were unbalanced, so reset the balancing interval */
3213 sd
->balance_interval
= sd
->min_interval
;
3216 * If we've begun active balancing, start to back off. This
3217 * case may not be covered by the all_pinned logic if there
3218 * is only 1 task on the busy runqueue (because we don't call
3221 if (sd
->balance_interval
< sd
->max_interval
)
3222 sd
->balance_interval
*= 2;
3225 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3226 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3231 schedstat_inc(sd
, lb_balanced
[idle
]);
3233 sd
->nr_balance_failed
= 0;
3236 /* tune up the balancing interval */
3237 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
3238 (sd
->balance_interval
< sd
->max_interval
))
3239 sd
->balance_interval
*= 2;
3241 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3242 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3248 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3249 * tasks if there is an imbalance.
3251 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
3252 * this_rq is locked.
3255 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
3257 struct sched_group
*group
;
3258 struct rq
*busiest
= NULL
;
3259 unsigned long imbalance
;
3263 cpumask_t cpus
= CPU_MASK_ALL
;
3266 * When power savings policy is enabled for the parent domain, idle
3267 * sibling can pick up load irrespective of busy siblings. In this case,
3268 * let the state of idle sibling percolate up as IDLE, instead of
3269 * portraying it as CPU_NOT_IDLE.
3271 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
3272 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3275 schedstat_inc(sd
, lb_count
[CPU_NEWLY_IDLE
]);
3277 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
3278 &sd_idle
, &cpus
, NULL
);
3280 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
3284 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
3287 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
3291 BUG_ON(busiest
== this_rq
);
3293 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
3296 if (busiest
->nr_running
> 1) {
3297 /* Attempt to move tasks */
3298 double_lock_balance(this_rq
, busiest
);
3299 /* this_rq->clock is already updated */
3300 update_rq_clock(busiest
);
3301 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
3302 imbalance
, sd
, CPU_NEWLY_IDLE
,
3304 spin_unlock(&busiest
->lock
);
3306 if (unlikely(all_pinned
)) {
3307 cpu_clear(cpu_of(busiest
), cpus
);
3308 if (!cpus_empty(cpus
))
3314 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
3315 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3316 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3319 sd
->nr_balance_failed
= 0;
3324 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
3325 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3326 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3328 sd
->nr_balance_failed
= 0;
3334 * idle_balance is called by schedule() if this_cpu is about to become
3335 * idle. Attempts to pull tasks from other CPUs.
3337 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
3339 struct sched_domain
*sd
;
3340 int pulled_task
= -1;
3341 unsigned long next_balance
= jiffies
+ HZ
;
3343 for_each_domain(this_cpu
, sd
) {
3344 unsigned long interval
;
3346 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3349 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
3350 /* If we've pulled tasks over stop searching: */
3351 pulled_task
= load_balance_newidle(this_cpu
,
3354 interval
= msecs_to_jiffies(sd
->balance_interval
);
3355 if (time_after(next_balance
, sd
->last_balance
+ interval
))
3356 next_balance
= sd
->last_balance
+ interval
;
3360 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
3362 * We are going idle. next_balance may be set based on
3363 * a busy processor. So reset next_balance.
3365 this_rq
->next_balance
= next_balance
;
3370 * active_load_balance is run by migration threads. It pushes running tasks
3371 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
3372 * running on each physical CPU where possible, and avoids physical /
3373 * logical imbalances.
3375 * Called with busiest_rq locked.
3377 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
3379 int target_cpu
= busiest_rq
->push_cpu
;
3380 struct sched_domain
*sd
;
3381 struct rq
*target_rq
;
3383 /* Is there any task to move? */
3384 if (busiest_rq
->nr_running
<= 1)
3387 target_rq
= cpu_rq(target_cpu
);
3390 * This condition is "impossible", if it occurs
3391 * we need to fix it. Originally reported by
3392 * Bjorn Helgaas on a 128-cpu setup.
3394 BUG_ON(busiest_rq
== target_rq
);
3396 /* move a task from busiest_rq to target_rq */
3397 double_lock_balance(busiest_rq
, target_rq
);
3398 update_rq_clock(busiest_rq
);
3399 update_rq_clock(target_rq
);
3401 /* Search for an sd spanning us and the target CPU. */
3402 for_each_domain(target_cpu
, sd
) {
3403 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
3404 cpu_isset(busiest_cpu
, sd
->span
))
3409 schedstat_inc(sd
, alb_count
);
3411 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
3413 schedstat_inc(sd
, alb_pushed
);
3415 schedstat_inc(sd
, alb_failed
);
3417 spin_unlock(&target_rq
->lock
);
3422 atomic_t load_balancer
;
3424 } nohz ____cacheline_aligned
= {
3425 .load_balancer
= ATOMIC_INIT(-1),
3426 .cpu_mask
= CPU_MASK_NONE
,
3430 * This routine will try to nominate the ilb (idle load balancing)
3431 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3432 * load balancing on behalf of all those cpus. If all the cpus in the system
3433 * go into this tickless mode, then there will be no ilb owner (as there is
3434 * no need for one) and all the cpus will sleep till the next wakeup event
3437 * For the ilb owner, tick is not stopped. And this tick will be used
3438 * for idle load balancing. ilb owner will still be part of
3441 * While stopping the tick, this cpu will become the ilb owner if there
3442 * is no other owner. And will be the owner till that cpu becomes busy
3443 * or if all cpus in the system stop their ticks at which point
3444 * there is no need for ilb owner.
3446 * When the ilb owner becomes busy, it nominates another owner, during the
3447 * next busy scheduler_tick()
3449 int select_nohz_load_balancer(int stop_tick
)
3451 int cpu
= smp_processor_id();
3454 cpu_set(cpu
, nohz
.cpu_mask
);
3455 cpu_rq(cpu
)->in_nohz_recently
= 1;
3458 * If we are going offline and still the leader, give up!
3460 if (cpu_is_offline(cpu
) &&
3461 atomic_read(&nohz
.load_balancer
) == cpu
) {
3462 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3467 /* time for ilb owner also to sleep */
3468 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3469 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3470 atomic_set(&nohz
.load_balancer
, -1);
3474 if (atomic_read(&nohz
.load_balancer
) == -1) {
3475 /* make me the ilb owner */
3476 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
3478 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
3481 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
3484 cpu_clear(cpu
, nohz
.cpu_mask
);
3486 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3487 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3494 static DEFINE_SPINLOCK(balancing
);
3497 * It checks each scheduling domain to see if it is due to be balanced,
3498 * and initiates a balancing operation if so.
3500 * Balancing parameters are set up in arch_init_sched_domains.
3502 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3505 struct rq
*rq
= cpu_rq(cpu
);
3506 unsigned long interval
;
3507 struct sched_domain
*sd
;
3508 /* Earliest time when we have to do rebalance again */
3509 unsigned long next_balance
= jiffies
+ 60*HZ
;
3510 int update_next_balance
= 0;
3512 for_each_domain(cpu
, sd
) {
3513 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3516 interval
= sd
->balance_interval
;
3517 if (idle
!= CPU_IDLE
)
3518 interval
*= sd
->busy_factor
;
3520 /* scale ms to jiffies */
3521 interval
= msecs_to_jiffies(interval
);
3522 if (unlikely(!interval
))
3524 if (interval
> HZ
*NR_CPUS
/10)
3525 interval
= HZ
*NR_CPUS
/10;
3528 if (sd
->flags
& SD_SERIALIZE
) {
3529 if (!spin_trylock(&balancing
))
3533 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3534 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3536 * We've pulled tasks over so either we're no
3537 * longer idle, or one of our SMT siblings is
3540 idle
= CPU_NOT_IDLE
;
3542 sd
->last_balance
= jiffies
;
3544 if (sd
->flags
& SD_SERIALIZE
)
3545 spin_unlock(&balancing
);
3547 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3548 next_balance
= sd
->last_balance
+ interval
;
3549 update_next_balance
= 1;
3553 * Stop the load balance at this level. There is another
3554 * CPU in our sched group which is doing load balancing more
3562 * next_balance will be updated only when there is a need.
3563 * When the cpu is attached to null domain for ex, it will not be
3566 if (likely(update_next_balance
))
3567 rq
->next_balance
= next_balance
;
3571 * run_rebalance_domains is triggered when needed from the scheduler tick.
3572 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3573 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3575 static void run_rebalance_domains(struct softirq_action
*h
)
3577 int this_cpu
= smp_processor_id();
3578 struct rq
*this_rq
= cpu_rq(this_cpu
);
3579 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3580 CPU_IDLE
: CPU_NOT_IDLE
;
3582 rebalance_domains(this_cpu
, idle
);
3586 * If this cpu is the owner for idle load balancing, then do the
3587 * balancing on behalf of the other idle cpus whose ticks are
3590 if (this_rq
->idle_at_tick
&&
3591 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3592 cpumask_t cpus
= nohz
.cpu_mask
;
3596 cpu_clear(this_cpu
, cpus
);
3597 for_each_cpu_mask(balance_cpu
, cpus
) {
3599 * If this cpu gets work to do, stop the load balancing
3600 * work being done for other cpus. Next load
3601 * balancing owner will pick it up.
3606 rebalance_domains(balance_cpu
, CPU_IDLE
);
3608 rq
= cpu_rq(balance_cpu
);
3609 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3610 this_rq
->next_balance
= rq
->next_balance
;
3617 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3619 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3620 * idle load balancing owner or decide to stop the periodic load balancing,
3621 * if the whole system is idle.
3623 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3627 * If we were in the nohz mode recently and busy at the current
3628 * scheduler tick, then check if we need to nominate new idle
3631 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3632 rq
->in_nohz_recently
= 0;
3634 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3635 cpu_clear(cpu
, nohz
.cpu_mask
);
3636 atomic_set(&nohz
.load_balancer
, -1);
3639 if (atomic_read(&nohz
.load_balancer
) == -1) {
3641 * simple selection for now: Nominate the
3642 * first cpu in the nohz list to be the next
3645 * TBD: Traverse the sched domains and nominate
3646 * the nearest cpu in the nohz.cpu_mask.
3648 int ilb
= first_cpu(nohz
.cpu_mask
);
3656 * If this cpu is idle and doing idle load balancing for all the
3657 * cpus with ticks stopped, is it time for that to stop?
3659 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3660 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3666 * If this cpu is idle and the idle load balancing is done by
3667 * someone else, then no need raise the SCHED_SOFTIRQ
3669 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3670 cpu_isset(cpu
, nohz
.cpu_mask
))
3673 if (time_after_eq(jiffies
, rq
->next_balance
))
3674 raise_softirq(SCHED_SOFTIRQ
);
3677 #else /* CONFIG_SMP */
3680 * on UP we do not need to balance between CPUs:
3682 static inline void idle_balance(int cpu
, struct rq
*rq
)
3688 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3690 EXPORT_PER_CPU_SYMBOL(kstat
);
3693 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3694 * that have not yet been banked in case the task is currently running.
3696 unsigned long long task_sched_runtime(struct task_struct
*p
)
3698 unsigned long flags
;
3702 rq
= task_rq_lock(p
, &flags
);
3703 ns
= p
->se
.sum_exec_runtime
;
3704 if (task_current(rq
, p
)) {
3705 update_rq_clock(rq
);
3706 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3707 if ((s64
)delta_exec
> 0)
3710 task_rq_unlock(rq
, &flags
);
3716 * Account user cpu time to a process.
3717 * @p: the process that the cpu time gets accounted to
3718 * @cputime: the cpu time spent in user space since the last update
3720 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3722 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3725 p
->utime
= cputime_add(p
->utime
, cputime
);
3727 /* Add user time to cpustat. */
3728 tmp
= cputime_to_cputime64(cputime
);
3729 if (TASK_NICE(p
) > 0)
3730 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3732 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3736 * Account guest cpu time to a process.
3737 * @p: the process that the cpu time gets accounted to
3738 * @cputime: the cpu time spent in virtual machine since the last update
3740 static void account_guest_time(struct task_struct
*p
, cputime_t cputime
)
3743 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3745 tmp
= cputime_to_cputime64(cputime
);
3747 p
->utime
= cputime_add(p
->utime
, cputime
);
3748 p
->gtime
= cputime_add(p
->gtime
, cputime
);
3750 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3751 cpustat
->guest
= cputime64_add(cpustat
->guest
, tmp
);
3755 * Account scaled user cpu time to a process.
3756 * @p: the process that the cpu time gets accounted to
3757 * @cputime: the cpu time spent in user space since the last update
3759 void account_user_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3761 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime
);
3765 * Account system cpu time to a process.
3766 * @p: the process that the cpu time gets accounted to
3767 * @hardirq_offset: the offset to subtract from hardirq_count()
3768 * @cputime: the cpu time spent in kernel space since the last update
3770 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3773 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3774 struct rq
*rq
= this_rq();
3777 if ((p
->flags
& PF_VCPU
) && (irq_count() - hardirq_offset
== 0))
3778 return account_guest_time(p
, cputime
);
3780 p
->stime
= cputime_add(p
->stime
, cputime
);
3782 /* Add system time to cpustat. */
3783 tmp
= cputime_to_cputime64(cputime
);
3784 if (hardirq_count() - hardirq_offset
)
3785 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3786 else if (softirq_count())
3787 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3788 else if (p
!= rq
->idle
)
3789 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3790 else if (atomic_read(&rq
->nr_iowait
) > 0)
3791 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3793 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3794 /* Account for system time used */
3795 acct_update_integrals(p
);
3799 * Account scaled system cpu time to a process.
3800 * @p: the process that the cpu time gets accounted to
3801 * @hardirq_offset: the offset to subtract from hardirq_count()
3802 * @cputime: the cpu time spent in kernel space since the last update
3804 void account_system_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3806 p
->stimescaled
= cputime_add(p
->stimescaled
, cputime
);
3810 * Account for involuntary wait time.
3811 * @p: the process from which the cpu time has been stolen
3812 * @steal: the cpu time spent in involuntary wait
3814 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3816 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3817 cputime64_t tmp
= cputime_to_cputime64(steal
);
3818 struct rq
*rq
= this_rq();
3820 if (p
== rq
->idle
) {
3821 p
->stime
= cputime_add(p
->stime
, steal
);
3822 if (atomic_read(&rq
->nr_iowait
) > 0)
3823 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3825 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3827 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3831 * This function gets called by the timer code, with HZ frequency.
3832 * We call it with interrupts disabled.
3834 * It also gets called by the fork code, when changing the parent's
3837 void scheduler_tick(void)
3839 int cpu
= smp_processor_id();
3840 struct rq
*rq
= cpu_rq(cpu
);
3841 struct task_struct
*curr
= rq
->curr
;
3842 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3844 spin_lock(&rq
->lock
);
3845 __update_rq_clock(rq
);
3847 * Let rq->clock advance by at least TICK_NSEC:
3849 if (unlikely(rq
->clock
< next_tick
)) {
3850 rq
->clock
= next_tick
;
3851 rq
->clock_underflows
++;
3853 rq
->tick_timestamp
= rq
->clock
;
3854 update_last_tick_seen(rq
);
3855 update_cpu_load(rq
);
3856 curr
->sched_class
->task_tick(rq
, curr
, 0);
3857 update_sched_rt_period(rq
);
3858 spin_unlock(&rq
->lock
);
3861 rq
->idle_at_tick
= idle_cpu(cpu
);
3862 trigger_load_balance(rq
, cpu
);
3866 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3868 void __kprobes
add_preempt_count(int val
)
3873 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3875 preempt_count() += val
;
3877 * Spinlock count overflowing soon?
3879 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3882 EXPORT_SYMBOL(add_preempt_count
);
3884 void __kprobes
sub_preempt_count(int val
)
3889 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3892 * Is the spinlock portion underflowing?
3894 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3895 !(preempt_count() & PREEMPT_MASK
)))
3898 preempt_count() -= val
;
3900 EXPORT_SYMBOL(sub_preempt_count
);
3905 * Print scheduling while atomic bug:
3907 static noinline
void __schedule_bug(struct task_struct
*prev
)
3909 struct pt_regs
*regs
= get_irq_regs();
3911 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3912 prev
->comm
, prev
->pid
, preempt_count());
3914 debug_show_held_locks(prev
);
3915 if (irqs_disabled())
3916 print_irqtrace_events(prev
);
3925 * Various schedule()-time debugging checks and statistics:
3927 static inline void schedule_debug(struct task_struct
*prev
)
3930 * Test if we are atomic. Since do_exit() needs to call into
3931 * schedule() atomically, we ignore that path for now.
3932 * Otherwise, whine if we are scheduling when we should not be.
3934 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3935 __schedule_bug(prev
);
3937 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3939 schedstat_inc(this_rq(), sched_count
);
3940 #ifdef CONFIG_SCHEDSTATS
3941 if (unlikely(prev
->lock_depth
>= 0)) {
3942 schedstat_inc(this_rq(), bkl_count
);
3943 schedstat_inc(prev
, sched_info
.bkl_count
);
3949 * Pick up the highest-prio task:
3951 static inline struct task_struct
*
3952 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3954 const struct sched_class
*class;
3955 struct task_struct
*p
;
3958 * Optimization: we know that if all tasks are in
3959 * the fair class we can call that function directly:
3961 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3962 p
= fair_sched_class
.pick_next_task(rq
);
3967 class = sched_class_highest
;
3969 p
= class->pick_next_task(rq
);
3973 * Will never be NULL as the idle class always
3974 * returns a non-NULL p:
3976 class = class->next
;
3981 * schedule() is the main scheduler function.
3983 asmlinkage
void __sched
schedule(void)
3985 struct task_struct
*prev
, *next
;
3986 unsigned long *switch_count
;
3992 cpu
= smp_processor_id();
3996 switch_count
= &prev
->nivcsw
;
3998 release_kernel_lock(prev
);
3999 need_resched_nonpreemptible
:
4001 schedule_debug(prev
);
4006 * Do the rq-clock update outside the rq lock:
4008 local_irq_disable();
4009 __update_rq_clock(rq
);
4010 spin_lock(&rq
->lock
);
4011 clear_tsk_need_resched(prev
);
4013 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
4014 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
4015 signal_pending(prev
))) {
4016 prev
->state
= TASK_RUNNING
;
4018 deactivate_task(rq
, prev
, 1);
4020 switch_count
= &prev
->nvcsw
;
4024 if (prev
->sched_class
->pre_schedule
)
4025 prev
->sched_class
->pre_schedule(rq
, prev
);
4028 if (unlikely(!rq
->nr_running
))
4029 idle_balance(cpu
, rq
);
4031 prev
->sched_class
->put_prev_task(rq
, prev
);
4032 next
= pick_next_task(rq
, prev
);
4034 sched_info_switch(prev
, next
);
4036 if (likely(prev
!= next
)) {
4041 context_switch(rq
, prev
, next
); /* unlocks the rq */
4043 * the context switch might have flipped the stack from under
4044 * us, hence refresh the local variables.
4046 cpu
= smp_processor_id();
4049 spin_unlock_irq(&rq
->lock
);
4053 if (unlikely(reacquire_kernel_lock(current
) < 0))
4054 goto need_resched_nonpreemptible
;
4056 preempt_enable_no_resched();
4057 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
4060 EXPORT_SYMBOL(schedule
);
4062 #ifdef CONFIG_PREEMPT
4064 * this is the entry point to schedule() from in-kernel preemption
4065 * off of preempt_enable. Kernel preemptions off return from interrupt
4066 * occur there and call schedule directly.
4068 asmlinkage
void __sched
preempt_schedule(void)
4070 struct thread_info
*ti
= current_thread_info();
4071 struct task_struct
*task
= current
;
4072 int saved_lock_depth
;
4075 * If there is a non-zero preempt_count or interrupts are disabled,
4076 * we do not want to preempt the current task. Just return..
4078 if (likely(ti
->preempt_count
|| irqs_disabled()))
4082 add_preempt_count(PREEMPT_ACTIVE
);
4085 * We keep the big kernel semaphore locked, but we
4086 * clear ->lock_depth so that schedule() doesnt
4087 * auto-release the semaphore:
4089 saved_lock_depth
= task
->lock_depth
;
4090 task
->lock_depth
= -1;
4092 task
->lock_depth
= saved_lock_depth
;
4093 sub_preempt_count(PREEMPT_ACTIVE
);
4096 * Check again in case we missed a preemption opportunity
4097 * between schedule and now.
4100 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
4102 EXPORT_SYMBOL(preempt_schedule
);
4105 * this is the entry point to schedule() from kernel preemption
4106 * off of irq context.
4107 * Note, that this is called and return with irqs disabled. This will
4108 * protect us against recursive calling from irq.
4110 asmlinkage
void __sched
preempt_schedule_irq(void)
4112 struct thread_info
*ti
= current_thread_info();
4113 struct task_struct
*task
= current
;
4114 int saved_lock_depth
;
4116 /* Catch callers which need to be fixed */
4117 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
4120 add_preempt_count(PREEMPT_ACTIVE
);
4123 * We keep the big kernel semaphore locked, but we
4124 * clear ->lock_depth so that schedule() doesnt
4125 * auto-release the semaphore:
4127 saved_lock_depth
= task
->lock_depth
;
4128 task
->lock_depth
= -1;
4131 local_irq_disable();
4132 task
->lock_depth
= saved_lock_depth
;
4133 sub_preempt_count(PREEMPT_ACTIVE
);
4136 * Check again in case we missed a preemption opportunity
4137 * between schedule and now.
4140 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
4143 #endif /* CONFIG_PREEMPT */
4145 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
4148 return try_to_wake_up(curr
->private, mode
, sync
);
4150 EXPORT_SYMBOL(default_wake_function
);
4153 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4154 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4155 * number) then we wake all the non-exclusive tasks and one exclusive task.
4157 * There are circumstances in which we can try to wake a task which has already
4158 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4159 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4161 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
4162 int nr_exclusive
, int sync
, void *key
)
4164 wait_queue_t
*curr
, *next
;
4166 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
4167 unsigned flags
= curr
->flags
;
4169 if (curr
->func(curr
, mode
, sync
, key
) &&
4170 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
4176 * __wake_up - wake up threads blocked on a waitqueue.
4178 * @mode: which threads
4179 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4180 * @key: is directly passed to the wakeup function
4182 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
4183 int nr_exclusive
, void *key
)
4185 unsigned long flags
;
4187 spin_lock_irqsave(&q
->lock
, flags
);
4188 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
4189 spin_unlock_irqrestore(&q
->lock
, flags
);
4191 EXPORT_SYMBOL(__wake_up
);
4194 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4196 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
4198 __wake_up_common(q
, mode
, 1, 0, NULL
);
4202 * __wake_up_sync - wake up threads blocked on a waitqueue.
4204 * @mode: which threads
4205 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4207 * The sync wakeup differs that the waker knows that it will schedule
4208 * away soon, so while the target thread will be woken up, it will not
4209 * be migrated to another CPU - ie. the two threads are 'synchronized'
4210 * with each other. This can prevent needless bouncing between CPUs.
4212 * On UP it can prevent extra preemption.
4215 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
4217 unsigned long flags
;
4223 if (unlikely(!nr_exclusive
))
4226 spin_lock_irqsave(&q
->lock
, flags
);
4227 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
4228 spin_unlock_irqrestore(&q
->lock
, flags
);
4230 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
4232 void complete(struct completion
*x
)
4234 unsigned long flags
;
4236 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4238 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
4239 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4241 EXPORT_SYMBOL(complete
);
4243 void complete_all(struct completion
*x
)
4245 unsigned long flags
;
4247 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4248 x
->done
+= UINT_MAX
/2;
4249 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
4250 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4252 EXPORT_SYMBOL(complete_all
);
4254 static inline long __sched
4255 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
4258 DECLARE_WAITQUEUE(wait
, current
);
4260 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
4261 __add_wait_queue_tail(&x
->wait
, &wait
);
4263 if ((state
== TASK_INTERRUPTIBLE
&&
4264 signal_pending(current
)) ||
4265 (state
== TASK_KILLABLE
&&
4266 fatal_signal_pending(current
))) {
4267 __remove_wait_queue(&x
->wait
, &wait
);
4268 return -ERESTARTSYS
;
4270 __set_current_state(state
);
4271 spin_unlock_irq(&x
->wait
.lock
);
4272 timeout
= schedule_timeout(timeout
);
4273 spin_lock_irq(&x
->wait
.lock
);
4275 __remove_wait_queue(&x
->wait
, &wait
);
4279 __remove_wait_queue(&x
->wait
, &wait
);
4286 wait_for_common(struct completion
*x
, long timeout
, int state
)
4290 spin_lock_irq(&x
->wait
.lock
);
4291 timeout
= do_wait_for_common(x
, timeout
, state
);
4292 spin_unlock_irq(&x
->wait
.lock
);
4296 void __sched
wait_for_completion(struct completion
*x
)
4298 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
4300 EXPORT_SYMBOL(wait_for_completion
);
4302 unsigned long __sched
4303 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
4305 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
4307 EXPORT_SYMBOL(wait_for_completion_timeout
);
4309 int __sched
wait_for_completion_interruptible(struct completion
*x
)
4311 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
4312 if (t
== -ERESTARTSYS
)
4316 EXPORT_SYMBOL(wait_for_completion_interruptible
);
4318 unsigned long __sched
4319 wait_for_completion_interruptible_timeout(struct completion
*x
,
4320 unsigned long timeout
)
4322 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
4324 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
4326 int __sched
wait_for_completion_killable(struct completion
*x
)
4328 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
4329 if (t
== -ERESTARTSYS
)
4333 EXPORT_SYMBOL(wait_for_completion_killable
);
4336 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
4338 unsigned long flags
;
4341 init_waitqueue_entry(&wait
, current
);
4343 __set_current_state(state
);
4345 spin_lock_irqsave(&q
->lock
, flags
);
4346 __add_wait_queue(q
, &wait
);
4347 spin_unlock(&q
->lock
);
4348 timeout
= schedule_timeout(timeout
);
4349 spin_lock_irq(&q
->lock
);
4350 __remove_wait_queue(q
, &wait
);
4351 spin_unlock_irqrestore(&q
->lock
, flags
);
4356 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
4358 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4360 EXPORT_SYMBOL(interruptible_sleep_on
);
4363 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4365 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
4367 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
4369 void __sched
sleep_on(wait_queue_head_t
*q
)
4371 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4373 EXPORT_SYMBOL(sleep_on
);
4375 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4377 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
4379 EXPORT_SYMBOL(sleep_on_timeout
);
4381 #ifdef CONFIG_RT_MUTEXES
4384 * rt_mutex_setprio - set the current priority of a task
4386 * @prio: prio value (kernel-internal form)
4388 * This function changes the 'effective' priority of a task. It does
4389 * not touch ->normal_prio like __setscheduler().
4391 * Used by the rt_mutex code to implement priority inheritance logic.
4393 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
4395 unsigned long flags
;
4396 int oldprio
, on_rq
, running
;
4398 const struct sched_class
*prev_class
= p
->sched_class
;
4400 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4402 rq
= task_rq_lock(p
, &flags
);
4403 update_rq_clock(rq
);
4406 on_rq
= p
->se
.on_rq
;
4407 running
= task_current(rq
, p
);
4409 dequeue_task(rq
, p
, 0);
4411 p
->sched_class
->put_prev_task(rq
, p
);
4414 p
->sched_class
= &rt_sched_class
;
4416 p
->sched_class
= &fair_sched_class
;
4421 p
->sched_class
->set_curr_task(rq
);
4423 enqueue_task(rq
, p
, 0);
4425 check_class_changed(rq
, p
, prev_class
, oldprio
, running
);
4427 task_rq_unlock(rq
, &flags
);
4432 void set_user_nice(struct task_struct
*p
, long nice
)
4434 int old_prio
, delta
, on_rq
;
4435 unsigned long flags
;
4438 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4441 * We have to be careful, if called from sys_setpriority(),
4442 * the task might be in the middle of scheduling on another CPU.
4444 rq
= task_rq_lock(p
, &flags
);
4445 update_rq_clock(rq
);
4447 * The RT priorities are set via sched_setscheduler(), but we still
4448 * allow the 'normal' nice value to be set - but as expected
4449 * it wont have any effect on scheduling until the task is
4450 * SCHED_FIFO/SCHED_RR:
4452 if (task_has_rt_policy(p
)) {
4453 p
->static_prio
= NICE_TO_PRIO(nice
);
4456 on_rq
= p
->se
.on_rq
;
4458 dequeue_task(rq
, p
, 0);
4462 p
->static_prio
= NICE_TO_PRIO(nice
);
4465 p
->prio
= effective_prio(p
);
4466 delta
= p
->prio
- old_prio
;
4469 enqueue_task(rq
, p
, 0);
4472 * If the task increased its priority or is running and
4473 * lowered its priority, then reschedule its CPU:
4475 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4476 resched_task(rq
->curr
);
4479 task_rq_unlock(rq
, &flags
);
4481 EXPORT_SYMBOL(set_user_nice
);
4484 * can_nice - check if a task can reduce its nice value
4488 int can_nice(const struct task_struct
*p
, const int nice
)
4490 /* convert nice value [19,-20] to rlimit style value [1,40] */
4491 int nice_rlim
= 20 - nice
;
4493 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4494 capable(CAP_SYS_NICE
));
4497 #ifdef __ARCH_WANT_SYS_NICE
4500 * sys_nice - change the priority of the current process.
4501 * @increment: priority increment
4503 * sys_setpriority is a more generic, but much slower function that
4504 * does similar things.
4506 asmlinkage
long sys_nice(int increment
)
4511 * Setpriority might change our priority at the same moment.
4512 * We don't have to worry. Conceptually one call occurs first
4513 * and we have a single winner.
4515 if (increment
< -40)
4520 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4526 if (increment
< 0 && !can_nice(current
, nice
))
4529 retval
= security_task_setnice(current
, nice
);
4533 set_user_nice(current
, nice
);
4540 * task_prio - return the priority value of a given task.
4541 * @p: the task in question.
4543 * This is the priority value as seen by users in /proc.
4544 * RT tasks are offset by -200. Normal tasks are centered
4545 * around 0, value goes from -16 to +15.
4547 int task_prio(const struct task_struct
*p
)
4549 return p
->prio
- MAX_RT_PRIO
;
4553 * task_nice - return the nice value of a given task.
4554 * @p: the task in question.
4556 int task_nice(const struct task_struct
*p
)
4558 return TASK_NICE(p
);
4560 EXPORT_SYMBOL(task_nice
);
4563 * idle_cpu - is a given cpu idle currently?
4564 * @cpu: the processor in question.
4566 int idle_cpu(int cpu
)
4568 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4572 * idle_task - return the idle task for a given cpu.
4573 * @cpu: the processor in question.
4575 struct task_struct
*idle_task(int cpu
)
4577 return cpu_rq(cpu
)->idle
;
4581 * find_process_by_pid - find a process with a matching PID value.
4582 * @pid: the pid in question.
4584 static struct task_struct
*find_process_by_pid(pid_t pid
)
4586 return pid
? find_task_by_vpid(pid
) : current
;
4589 /* Actually do priority change: must hold rq lock. */
4591 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4593 BUG_ON(p
->se
.on_rq
);
4596 switch (p
->policy
) {
4600 p
->sched_class
= &fair_sched_class
;
4604 p
->sched_class
= &rt_sched_class
;
4608 p
->rt_priority
= prio
;
4609 p
->normal_prio
= normal_prio(p
);
4610 /* we are holding p->pi_lock already */
4611 p
->prio
= rt_mutex_getprio(p
);
4616 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4617 * @p: the task in question.
4618 * @policy: new policy.
4619 * @param: structure containing the new RT priority.
4621 * NOTE that the task may be already dead.
4623 int sched_setscheduler(struct task_struct
*p
, int policy
,
4624 struct sched_param
*param
)
4626 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
4627 unsigned long flags
;
4628 const struct sched_class
*prev_class
= p
->sched_class
;
4631 /* may grab non-irq protected spin_locks */
4632 BUG_ON(in_interrupt());
4634 /* double check policy once rq lock held */
4636 policy
= oldpolicy
= p
->policy
;
4637 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4638 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4639 policy
!= SCHED_IDLE
)
4642 * Valid priorities for SCHED_FIFO and SCHED_RR are
4643 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4644 * SCHED_BATCH and SCHED_IDLE is 0.
4646 if (param
->sched_priority
< 0 ||
4647 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4648 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4650 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4654 * Allow unprivileged RT tasks to decrease priority:
4656 if (!capable(CAP_SYS_NICE
)) {
4657 if (rt_policy(policy
)) {
4658 unsigned long rlim_rtprio
;
4660 if (!lock_task_sighand(p
, &flags
))
4662 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4663 unlock_task_sighand(p
, &flags
);
4665 /* can't set/change the rt policy */
4666 if (policy
!= p
->policy
&& !rlim_rtprio
)
4669 /* can't increase priority */
4670 if (param
->sched_priority
> p
->rt_priority
&&
4671 param
->sched_priority
> rlim_rtprio
)
4675 * Like positive nice levels, dont allow tasks to
4676 * move out of SCHED_IDLE either:
4678 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4681 /* can't change other user's priorities */
4682 if ((current
->euid
!= p
->euid
) &&
4683 (current
->euid
!= p
->uid
))
4687 #ifdef CONFIG_RT_GROUP_SCHED
4689 * Do not allow realtime tasks into groups that have no runtime
4692 if (rt_policy(policy
) && task_group(p
)->rt_runtime
== 0)
4696 retval
= security_task_setscheduler(p
, policy
, param
);
4700 * make sure no PI-waiters arrive (or leave) while we are
4701 * changing the priority of the task:
4703 spin_lock_irqsave(&p
->pi_lock
, flags
);
4705 * To be able to change p->policy safely, the apropriate
4706 * runqueue lock must be held.
4708 rq
= __task_rq_lock(p
);
4709 /* recheck policy now with rq lock held */
4710 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4711 policy
= oldpolicy
= -1;
4712 __task_rq_unlock(rq
);
4713 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4716 update_rq_clock(rq
);
4717 on_rq
= p
->se
.on_rq
;
4718 running
= task_current(rq
, p
);
4720 deactivate_task(rq
, p
, 0);
4722 p
->sched_class
->put_prev_task(rq
, p
);
4725 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4728 p
->sched_class
->set_curr_task(rq
);
4730 activate_task(rq
, p
, 0);
4732 check_class_changed(rq
, p
, prev_class
, oldprio
, running
);
4734 __task_rq_unlock(rq
);
4735 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4737 rt_mutex_adjust_pi(p
);
4741 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4744 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4746 struct sched_param lparam
;
4747 struct task_struct
*p
;
4750 if (!param
|| pid
< 0)
4752 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4757 p
= find_process_by_pid(pid
);
4759 retval
= sched_setscheduler(p
, policy
, &lparam
);
4766 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4767 * @pid: the pid in question.
4768 * @policy: new policy.
4769 * @param: structure containing the new RT priority.
4772 sys_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4774 /* negative values for policy are not valid */
4778 return do_sched_setscheduler(pid
, policy
, param
);
4782 * sys_sched_setparam - set/change the RT priority of a thread
4783 * @pid: the pid in question.
4784 * @param: structure containing the new RT priority.
4786 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4788 return do_sched_setscheduler(pid
, -1, param
);
4792 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4793 * @pid: the pid in question.
4795 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4797 struct task_struct
*p
;
4804 read_lock(&tasklist_lock
);
4805 p
= find_process_by_pid(pid
);
4807 retval
= security_task_getscheduler(p
);
4811 read_unlock(&tasklist_lock
);
4816 * sys_sched_getscheduler - get the RT priority of a thread
4817 * @pid: the pid in question.
4818 * @param: structure containing the RT priority.
4820 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4822 struct sched_param lp
;
4823 struct task_struct
*p
;
4826 if (!param
|| pid
< 0)
4829 read_lock(&tasklist_lock
);
4830 p
= find_process_by_pid(pid
);
4835 retval
= security_task_getscheduler(p
);
4839 lp
.sched_priority
= p
->rt_priority
;
4840 read_unlock(&tasklist_lock
);
4843 * This one might sleep, we cannot do it with a spinlock held ...
4845 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4850 read_unlock(&tasklist_lock
);
4854 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4856 cpumask_t cpus_allowed
;
4857 struct task_struct
*p
;
4861 read_lock(&tasklist_lock
);
4863 p
= find_process_by_pid(pid
);
4865 read_unlock(&tasklist_lock
);
4871 * It is not safe to call set_cpus_allowed with the
4872 * tasklist_lock held. We will bump the task_struct's
4873 * usage count and then drop tasklist_lock.
4876 read_unlock(&tasklist_lock
);
4879 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4880 !capable(CAP_SYS_NICE
))
4883 retval
= security_task_setscheduler(p
, 0, NULL
);
4887 cpus_allowed
= cpuset_cpus_allowed(p
);
4888 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4890 retval
= set_cpus_allowed(p
, new_mask
);
4893 cpus_allowed
= cpuset_cpus_allowed(p
);
4894 if (!cpus_subset(new_mask
, cpus_allowed
)) {
4896 * We must have raced with a concurrent cpuset
4897 * update. Just reset the cpus_allowed to the
4898 * cpuset's cpus_allowed
4900 new_mask
= cpus_allowed
;
4910 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4911 cpumask_t
*new_mask
)
4913 if (len
< sizeof(cpumask_t
)) {
4914 memset(new_mask
, 0, sizeof(cpumask_t
));
4915 } else if (len
> sizeof(cpumask_t
)) {
4916 len
= sizeof(cpumask_t
);
4918 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4922 * sys_sched_setaffinity - set the cpu affinity of a process
4923 * @pid: pid of the process
4924 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4925 * @user_mask_ptr: user-space pointer to the new cpu mask
4927 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4928 unsigned long __user
*user_mask_ptr
)
4933 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4937 return sched_setaffinity(pid
, new_mask
);
4941 * Represents all cpu's present in the system
4942 * In systems capable of hotplug, this map could dynamically grow
4943 * as new cpu's are detected in the system via any platform specific
4944 * method, such as ACPI for e.g.
4947 cpumask_t cpu_present_map __read_mostly
;
4948 EXPORT_SYMBOL(cpu_present_map
);
4951 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4952 EXPORT_SYMBOL(cpu_online_map
);
4954 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4955 EXPORT_SYMBOL(cpu_possible_map
);
4958 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4960 struct task_struct
*p
;
4964 read_lock(&tasklist_lock
);
4967 p
= find_process_by_pid(pid
);
4971 retval
= security_task_getscheduler(p
);
4975 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4978 read_unlock(&tasklist_lock
);
4985 * sys_sched_getaffinity - get the cpu affinity of a process
4986 * @pid: pid of the process
4987 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4988 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4990 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4991 unsigned long __user
*user_mask_ptr
)
4996 if (len
< sizeof(cpumask_t
))
4999 ret
= sched_getaffinity(pid
, &mask
);
5003 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
5006 return sizeof(cpumask_t
);
5010 * sys_sched_yield - yield the current processor to other threads.
5012 * This function yields the current CPU to other tasks. If there are no
5013 * other threads running on this CPU then this function will return.
5015 asmlinkage
long sys_sched_yield(void)
5017 struct rq
*rq
= this_rq_lock();
5019 schedstat_inc(rq
, yld_count
);
5020 current
->sched_class
->yield_task(rq
);
5023 * Since we are going to call schedule() anyway, there's
5024 * no need to preempt or enable interrupts:
5026 __release(rq
->lock
);
5027 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
5028 _raw_spin_unlock(&rq
->lock
);
5029 preempt_enable_no_resched();
5036 static void __cond_resched(void)
5038 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5039 __might_sleep(__FILE__
, __LINE__
);
5042 * The BKS might be reacquired before we have dropped
5043 * PREEMPT_ACTIVE, which could trigger a second
5044 * cond_resched() call.
5047 add_preempt_count(PREEMPT_ACTIVE
);
5049 sub_preempt_count(PREEMPT_ACTIVE
);
5050 } while (need_resched());
5053 #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)
5054 int __sched
_cond_resched(void)
5056 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
5057 system_state
== SYSTEM_RUNNING
) {
5063 EXPORT_SYMBOL(_cond_resched
);
5067 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
5068 * call schedule, and on return reacquire the lock.
5070 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5071 * operations here to prevent schedule() from being called twice (once via
5072 * spin_unlock(), once by hand).
5074 int cond_resched_lock(spinlock_t
*lock
)
5076 int resched
= need_resched() && system_state
== SYSTEM_RUNNING
;
5079 if (spin_needbreak(lock
) || resched
) {
5081 if (resched
&& need_resched())
5090 EXPORT_SYMBOL(cond_resched_lock
);
5092 int __sched
cond_resched_softirq(void)
5094 BUG_ON(!in_softirq());
5096 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
5104 EXPORT_SYMBOL(cond_resched_softirq
);
5107 * yield - yield the current processor to other threads.
5109 * This is a shortcut for kernel-space yielding - it marks the
5110 * thread runnable and calls sys_sched_yield().
5112 void __sched
yield(void)
5114 set_current_state(TASK_RUNNING
);
5117 EXPORT_SYMBOL(yield
);
5120 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5121 * that process accounting knows that this is a task in IO wait state.
5123 * But don't do that if it is a deliberate, throttling IO wait (this task
5124 * has set its backing_dev_info: the queue against which it should throttle)
5126 void __sched
io_schedule(void)
5128 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
5130 delayacct_blkio_start();
5131 atomic_inc(&rq
->nr_iowait
);
5133 atomic_dec(&rq
->nr_iowait
);
5134 delayacct_blkio_end();
5136 EXPORT_SYMBOL(io_schedule
);
5138 long __sched
io_schedule_timeout(long timeout
)
5140 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
5143 delayacct_blkio_start();
5144 atomic_inc(&rq
->nr_iowait
);
5145 ret
= schedule_timeout(timeout
);
5146 atomic_dec(&rq
->nr_iowait
);
5147 delayacct_blkio_end();
5152 * sys_sched_get_priority_max - return maximum RT priority.
5153 * @policy: scheduling class.
5155 * this syscall returns the maximum rt_priority that can be used
5156 * by a given scheduling class.
5158 asmlinkage
long sys_sched_get_priority_max(int policy
)
5165 ret
= MAX_USER_RT_PRIO
-1;
5177 * sys_sched_get_priority_min - return minimum RT priority.
5178 * @policy: scheduling class.
5180 * this syscall returns the minimum rt_priority that can be used
5181 * by a given scheduling class.
5183 asmlinkage
long sys_sched_get_priority_min(int policy
)
5201 * sys_sched_rr_get_interval - return the default timeslice of a process.
5202 * @pid: pid of the process.
5203 * @interval: userspace pointer to the timeslice value.
5205 * this syscall writes the default timeslice value of a given process
5206 * into the user-space timespec buffer. A value of '0' means infinity.
5209 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
5211 struct task_struct
*p
;
5212 unsigned int time_slice
;
5220 read_lock(&tasklist_lock
);
5221 p
= find_process_by_pid(pid
);
5225 retval
= security_task_getscheduler(p
);
5230 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
5231 * tasks that are on an otherwise idle runqueue:
5234 if (p
->policy
== SCHED_RR
) {
5235 time_slice
= DEF_TIMESLICE
;
5236 } else if (p
->policy
!= SCHED_FIFO
) {
5237 struct sched_entity
*se
= &p
->se
;
5238 unsigned long flags
;
5241 rq
= task_rq_lock(p
, &flags
);
5242 if (rq
->cfs
.load
.weight
)
5243 time_slice
= NS_TO_JIFFIES(sched_slice(&rq
->cfs
, se
));
5244 task_rq_unlock(rq
, &flags
);
5246 read_unlock(&tasklist_lock
);
5247 jiffies_to_timespec(time_slice
, &t
);
5248 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
5252 read_unlock(&tasklist_lock
);
5256 static const char stat_nam
[] = "RSDTtZX";
5258 void sched_show_task(struct task_struct
*p
)
5260 unsigned long free
= 0;
5263 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
5264 printk(KERN_INFO
"%-13.13s %c", p
->comm
,
5265 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
5266 #if BITS_PER_LONG == 32
5267 if (state
== TASK_RUNNING
)
5268 printk(KERN_CONT
" running ");
5270 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
5272 if (state
== TASK_RUNNING
)
5273 printk(KERN_CONT
" running task ");
5275 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
5277 #ifdef CONFIG_DEBUG_STACK_USAGE
5279 unsigned long *n
= end_of_stack(p
);
5282 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
5285 printk(KERN_CONT
"%5lu %5d %6d\n", free
,
5286 task_pid_nr(p
), task_pid_nr(p
->real_parent
));
5288 show_stack(p
, NULL
);
5291 void show_state_filter(unsigned long state_filter
)
5293 struct task_struct
*g
, *p
;
5295 #if BITS_PER_LONG == 32
5297 " task PC stack pid father\n");
5300 " task PC stack pid father\n");
5302 read_lock(&tasklist_lock
);
5303 do_each_thread(g
, p
) {
5305 * reset the NMI-timeout, listing all files on a slow
5306 * console might take alot of time:
5308 touch_nmi_watchdog();
5309 if (!state_filter
|| (p
->state
& state_filter
))
5311 } while_each_thread(g
, p
);
5313 touch_all_softlockup_watchdogs();
5315 #ifdef CONFIG_SCHED_DEBUG
5316 sysrq_sched_debug_show();
5318 read_unlock(&tasklist_lock
);
5320 * Only show locks if all tasks are dumped:
5322 if (state_filter
== -1)
5323 debug_show_all_locks();
5326 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
5328 idle
->sched_class
= &idle_sched_class
;
5332 * init_idle - set up an idle thread for a given CPU
5333 * @idle: task in question
5334 * @cpu: cpu the idle task belongs to
5336 * NOTE: this function does not set the idle thread's NEED_RESCHED
5337 * flag, to make booting more robust.
5339 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
5341 struct rq
*rq
= cpu_rq(cpu
);
5342 unsigned long flags
;
5345 idle
->se
.exec_start
= sched_clock();
5347 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
5348 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
5349 __set_task_cpu(idle
, cpu
);
5351 spin_lock_irqsave(&rq
->lock
, flags
);
5352 rq
->curr
= rq
->idle
= idle
;
5353 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5356 spin_unlock_irqrestore(&rq
->lock
, flags
);
5358 /* Set the preempt count _outside_ the spinlocks! */
5359 task_thread_info(idle
)->preempt_count
= 0;
5362 * The idle tasks have their own, simple scheduling class:
5364 idle
->sched_class
= &idle_sched_class
;
5368 * In a system that switches off the HZ timer nohz_cpu_mask
5369 * indicates which cpus entered this state. This is used
5370 * in the rcu update to wait only for active cpus. For system
5371 * which do not switch off the HZ timer nohz_cpu_mask should
5372 * always be CPU_MASK_NONE.
5374 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
5377 * Increase the granularity value when there are more CPUs,
5378 * because with more CPUs the 'effective latency' as visible
5379 * to users decreases. But the relationship is not linear,
5380 * so pick a second-best guess by going with the log2 of the
5383 * This idea comes from the SD scheduler of Con Kolivas:
5385 static inline void sched_init_granularity(void)
5387 unsigned int factor
= 1 + ilog2(num_online_cpus());
5388 const unsigned long limit
= 200000000;
5390 sysctl_sched_min_granularity
*= factor
;
5391 if (sysctl_sched_min_granularity
> limit
)
5392 sysctl_sched_min_granularity
= limit
;
5394 sysctl_sched_latency
*= factor
;
5395 if (sysctl_sched_latency
> limit
)
5396 sysctl_sched_latency
= limit
;
5398 sysctl_sched_wakeup_granularity
*= factor
;
5403 * This is how migration works:
5405 * 1) we queue a struct migration_req structure in the source CPU's
5406 * runqueue and wake up that CPU's migration thread.
5407 * 2) we down() the locked semaphore => thread blocks.
5408 * 3) migration thread wakes up (implicitly it forces the migrated
5409 * thread off the CPU)
5410 * 4) it gets the migration request and checks whether the migrated
5411 * task is still in the wrong runqueue.
5412 * 5) if it's in the wrong runqueue then the migration thread removes
5413 * it and puts it into the right queue.
5414 * 6) migration thread up()s the semaphore.
5415 * 7) we wake up and the migration is done.
5419 * Change a given task's CPU affinity. Migrate the thread to a
5420 * proper CPU and schedule it away if the CPU it's executing on
5421 * is removed from the allowed bitmask.
5423 * NOTE: the caller must have a valid reference to the task, the
5424 * task must not exit() & deallocate itself prematurely. The
5425 * call is not atomic; no spinlocks may be held.
5427 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5429 struct migration_req req
;
5430 unsigned long flags
;
5434 rq
= task_rq_lock(p
, &flags
);
5435 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5440 if (p
->sched_class
->set_cpus_allowed
)
5441 p
->sched_class
->set_cpus_allowed(p
, &new_mask
);
5443 p
->cpus_allowed
= new_mask
;
5444 p
->rt
.nr_cpus_allowed
= cpus_weight(new_mask
);
5447 /* Can the task run on the task's current CPU? If so, we're done */
5448 if (cpu_isset(task_cpu(p
), new_mask
))
5451 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5452 /* Need help from migration thread: drop lock and wait. */
5453 task_rq_unlock(rq
, &flags
);
5454 wake_up_process(rq
->migration_thread
);
5455 wait_for_completion(&req
.done
);
5456 tlb_migrate_finish(p
->mm
);
5460 task_rq_unlock(rq
, &flags
);
5464 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5467 * Move (not current) task off this cpu, onto dest cpu. We're doing
5468 * this because either it can't run here any more (set_cpus_allowed()
5469 * away from this CPU, or CPU going down), or because we're
5470 * attempting to rebalance this task on exec (sched_exec).
5472 * So we race with normal scheduler movements, but that's OK, as long
5473 * as the task is no longer on this CPU.
5475 * Returns non-zero if task was successfully migrated.
5477 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5479 struct rq
*rq_dest
, *rq_src
;
5482 if (unlikely(cpu_is_offline(dest_cpu
)))
5485 rq_src
= cpu_rq(src_cpu
);
5486 rq_dest
= cpu_rq(dest_cpu
);
5488 double_rq_lock(rq_src
, rq_dest
);
5489 /* Already moved. */
5490 if (task_cpu(p
) != src_cpu
)
5492 /* Affinity changed (again). */
5493 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5496 on_rq
= p
->se
.on_rq
;
5498 deactivate_task(rq_src
, p
, 0);
5500 set_task_cpu(p
, dest_cpu
);
5502 activate_task(rq_dest
, p
, 0);
5503 check_preempt_curr(rq_dest
, p
);
5507 double_rq_unlock(rq_src
, rq_dest
);
5512 * migration_thread - this is a highprio system thread that performs
5513 * thread migration by bumping thread off CPU then 'pushing' onto
5516 static int migration_thread(void *data
)
5518 int cpu
= (long)data
;
5522 BUG_ON(rq
->migration_thread
!= current
);
5524 set_current_state(TASK_INTERRUPTIBLE
);
5525 while (!kthread_should_stop()) {
5526 struct migration_req
*req
;
5527 struct list_head
*head
;
5529 spin_lock_irq(&rq
->lock
);
5531 if (cpu_is_offline(cpu
)) {
5532 spin_unlock_irq(&rq
->lock
);
5536 if (rq
->active_balance
) {
5537 active_load_balance(rq
, cpu
);
5538 rq
->active_balance
= 0;
5541 head
= &rq
->migration_queue
;
5543 if (list_empty(head
)) {
5544 spin_unlock_irq(&rq
->lock
);
5546 set_current_state(TASK_INTERRUPTIBLE
);
5549 req
= list_entry(head
->next
, struct migration_req
, list
);
5550 list_del_init(head
->next
);
5552 spin_unlock(&rq
->lock
);
5553 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5556 complete(&req
->done
);
5558 __set_current_state(TASK_RUNNING
);
5562 /* Wait for kthread_stop */
5563 set_current_state(TASK_INTERRUPTIBLE
);
5564 while (!kthread_should_stop()) {
5566 set_current_state(TASK_INTERRUPTIBLE
);
5568 __set_current_state(TASK_RUNNING
);
5572 #ifdef CONFIG_HOTPLUG_CPU
5574 static int __migrate_task_irq(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5578 local_irq_disable();
5579 ret
= __migrate_task(p
, src_cpu
, dest_cpu
);
5585 * Figure out where task on dead CPU should go, use force if necessary.
5586 * NOTE: interrupts should be disabled by the caller
5588 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5590 unsigned long flags
;
5597 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5598 cpus_and(mask
, mask
, p
->cpus_allowed
);
5599 dest_cpu
= any_online_cpu(mask
);
5601 /* On any allowed CPU? */
5602 if (dest_cpu
== NR_CPUS
)
5603 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5605 /* No more Mr. Nice Guy. */
5606 if (dest_cpu
== NR_CPUS
) {
5607 cpumask_t cpus_allowed
= cpuset_cpus_allowed_locked(p
);
5609 * Try to stay on the same cpuset, where the
5610 * current cpuset may be a subset of all cpus.
5611 * The cpuset_cpus_allowed_locked() variant of
5612 * cpuset_cpus_allowed() will not block. It must be
5613 * called within calls to cpuset_lock/cpuset_unlock.
5615 rq
= task_rq_lock(p
, &flags
);
5616 p
->cpus_allowed
= cpus_allowed
;
5617 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5618 task_rq_unlock(rq
, &flags
);
5621 * Don't tell them about moving exiting tasks or
5622 * kernel threads (both mm NULL), since they never
5625 if (p
->mm
&& printk_ratelimit()) {
5626 printk(KERN_INFO
"process %d (%s) no "
5627 "longer affine to cpu%d\n",
5628 task_pid_nr(p
), p
->comm
, dead_cpu
);
5631 } while (!__migrate_task_irq(p
, dead_cpu
, dest_cpu
));
5635 * While a dead CPU has no uninterruptible tasks queued at this point,
5636 * it might still have a nonzero ->nr_uninterruptible counter, because
5637 * for performance reasons the counter is not stricly tracking tasks to
5638 * their home CPUs. So we just add the counter to another CPU's counter,
5639 * to keep the global sum constant after CPU-down:
5641 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5643 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5644 unsigned long flags
;
5646 local_irq_save(flags
);
5647 double_rq_lock(rq_src
, rq_dest
);
5648 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5649 rq_src
->nr_uninterruptible
= 0;
5650 double_rq_unlock(rq_src
, rq_dest
);
5651 local_irq_restore(flags
);
5654 /* Run through task list and migrate tasks from the dead cpu. */
5655 static void migrate_live_tasks(int src_cpu
)
5657 struct task_struct
*p
, *t
;
5659 read_lock(&tasklist_lock
);
5661 do_each_thread(t
, p
) {
5665 if (task_cpu(p
) == src_cpu
)
5666 move_task_off_dead_cpu(src_cpu
, p
);
5667 } while_each_thread(t
, p
);
5669 read_unlock(&tasklist_lock
);
5673 * Schedules idle task to be the next runnable task on current CPU.
5674 * It does so by boosting its priority to highest possible.
5675 * Used by CPU offline code.
5677 void sched_idle_next(void)
5679 int this_cpu
= smp_processor_id();
5680 struct rq
*rq
= cpu_rq(this_cpu
);
5681 struct task_struct
*p
= rq
->idle
;
5682 unsigned long flags
;
5684 /* cpu has to be offline */
5685 BUG_ON(cpu_online(this_cpu
));
5688 * Strictly not necessary since rest of the CPUs are stopped by now
5689 * and interrupts disabled on the current cpu.
5691 spin_lock_irqsave(&rq
->lock
, flags
);
5693 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5695 update_rq_clock(rq
);
5696 activate_task(rq
, p
, 0);
5698 spin_unlock_irqrestore(&rq
->lock
, flags
);
5702 * Ensures that the idle task is using init_mm right before its cpu goes
5705 void idle_task_exit(void)
5707 struct mm_struct
*mm
= current
->active_mm
;
5709 BUG_ON(cpu_online(smp_processor_id()));
5712 switch_mm(mm
, &init_mm
, current
);
5716 /* called under rq->lock with disabled interrupts */
5717 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5719 struct rq
*rq
= cpu_rq(dead_cpu
);
5721 /* Must be exiting, otherwise would be on tasklist. */
5722 BUG_ON(!p
->exit_state
);
5724 /* Cannot have done final schedule yet: would have vanished. */
5725 BUG_ON(p
->state
== TASK_DEAD
);
5730 * Drop lock around migration; if someone else moves it,
5731 * that's OK. No task can be added to this CPU, so iteration is
5734 spin_unlock_irq(&rq
->lock
);
5735 move_task_off_dead_cpu(dead_cpu
, p
);
5736 spin_lock_irq(&rq
->lock
);
5741 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5742 static void migrate_dead_tasks(unsigned int dead_cpu
)
5744 struct rq
*rq
= cpu_rq(dead_cpu
);
5745 struct task_struct
*next
;
5748 if (!rq
->nr_running
)
5750 update_rq_clock(rq
);
5751 next
= pick_next_task(rq
, rq
->curr
);
5754 migrate_dead(dead_cpu
, next
);
5758 #endif /* CONFIG_HOTPLUG_CPU */
5760 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5762 static struct ctl_table sd_ctl_dir
[] = {
5764 .procname
= "sched_domain",
5770 static struct ctl_table sd_ctl_root
[] = {
5772 .ctl_name
= CTL_KERN
,
5773 .procname
= "kernel",
5775 .child
= sd_ctl_dir
,
5780 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5782 struct ctl_table
*entry
=
5783 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5788 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5790 struct ctl_table
*entry
;
5793 * In the intermediate directories, both the child directory and
5794 * procname are dynamically allocated and could fail but the mode
5795 * will always be set. In the lowest directory the names are
5796 * static strings and all have proc handlers.
5798 for (entry
= *tablep
; entry
->mode
; entry
++) {
5800 sd_free_ctl_entry(&entry
->child
);
5801 if (entry
->proc_handler
== NULL
)
5802 kfree(entry
->procname
);
5810 set_table_entry(struct ctl_table
*entry
,
5811 const char *procname
, void *data
, int maxlen
,
5812 mode_t mode
, proc_handler
*proc_handler
)
5814 entry
->procname
= procname
;
5816 entry
->maxlen
= maxlen
;
5818 entry
->proc_handler
= proc_handler
;
5821 static struct ctl_table
*
5822 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5824 struct ctl_table
*table
= sd_alloc_ctl_entry(12);
5829 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5830 sizeof(long), 0644, proc_doulongvec_minmax
);
5831 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5832 sizeof(long), 0644, proc_doulongvec_minmax
);
5833 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5834 sizeof(int), 0644, proc_dointvec_minmax
);
5835 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5836 sizeof(int), 0644, proc_dointvec_minmax
);
5837 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5838 sizeof(int), 0644, proc_dointvec_minmax
);
5839 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5840 sizeof(int), 0644, proc_dointvec_minmax
);
5841 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5842 sizeof(int), 0644, proc_dointvec_minmax
);
5843 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5844 sizeof(int), 0644, proc_dointvec_minmax
);
5845 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5846 sizeof(int), 0644, proc_dointvec_minmax
);
5847 set_table_entry(&table
[9], "cache_nice_tries",
5848 &sd
->cache_nice_tries
,
5849 sizeof(int), 0644, proc_dointvec_minmax
);
5850 set_table_entry(&table
[10], "flags", &sd
->flags
,
5851 sizeof(int), 0644, proc_dointvec_minmax
);
5852 /* &table[11] is terminator */
5857 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5859 struct ctl_table
*entry
, *table
;
5860 struct sched_domain
*sd
;
5861 int domain_num
= 0, i
;
5864 for_each_domain(cpu
, sd
)
5866 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5871 for_each_domain(cpu
, sd
) {
5872 snprintf(buf
, 32, "domain%d", i
);
5873 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5875 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5882 static struct ctl_table_header
*sd_sysctl_header
;
5883 static void register_sched_domain_sysctl(void)
5885 int i
, cpu_num
= num_online_cpus();
5886 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5889 WARN_ON(sd_ctl_dir
[0].child
);
5890 sd_ctl_dir
[0].child
= entry
;
5895 for_each_online_cpu(i
) {
5896 snprintf(buf
, 32, "cpu%d", i
);
5897 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5899 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5903 WARN_ON(sd_sysctl_header
);
5904 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5907 /* may be called multiple times per register */
5908 static void unregister_sched_domain_sysctl(void)
5910 if (sd_sysctl_header
)
5911 unregister_sysctl_table(sd_sysctl_header
);
5912 sd_sysctl_header
= NULL
;
5913 if (sd_ctl_dir
[0].child
)
5914 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5917 static void register_sched_domain_sysctl(void)
5920 static void unregister_sched_domain_sysctl(void)
5926 * migration_call - callback that gets triggered when a CPU is added.
5927 * Here we can start up the necessary migration thread for the new CPU.
5929 static int __cpuinit
5930 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5932 struct task_struct
*p
;
5933 int cpu
= (long)hcpu
;
5934 unsigned long flags
;
5939 case CPU_UP_PREPARE
:
5940 case CPU_UP_PREPARE_FROZEN
:
5941 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5944 kthread_bind(p
, cpu
);
5945 /* Must be high prio: stop_machine expects to yield to it. */
5946 rq
= task_rq_lock(p
, &flags
);
5947 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5948 task_rq_unlock(rq
, &flags
);
5949 cpu_rq(cpu
)->migration_thread
= p
;
5953 case CPU_ONLINE_FROZEN
:
5954 /* Strictly unnecessary, as first user will wake it. */
5955 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5957 /* Update our root-domain */
5959 spin_lock_irqsave(&rq
->lock
, flags
);
5961 BUG_ON(!cpu_isset(cpu
, rq
->rd
->span
));
5962 cpu_set(cpu
, rq
->rd
->online
);
5964 spin_unlock_irqrestore(&rq
->lock
, flags
);
5967 #ifdef CONFIG_HOTPLUG_CPU
5968 case CPU_UP_CANCELED
:
5969 case CPU_UP_CANCELED_FROZEN
:
5970 if (!cpu_rq(cpu
)->migration_thread
)
5972 /* Unbind it from offline cpu so it can run. Fall thru. */
5973 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5974 any_online_cpu(cpu_online_map
));
5975 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5976 cpu_rq(cpu
)->migration_thread
= NULL
;
5980 case CPU_DEAD_FROZEN
:
5981 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
5982 migrate_live_tasks(cpu
);
5984 kthread_stop(rq
->migration_thread
);
5985 rq
->migration_thread
= NULL
;
5986 /* Idle task back to normal (off runqueue, low prio) */
5987 spin_lock_irq(&rq
->lock
);
5988 update_rq_clock(rq
);
5989 deactivate_task(rq
, rq
->idle
, 0);
5990 rq
->idle
->static_prio
= MAX_PRIO
;
5991 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5992 rq
->idle
->sched_class
= &idle_sched_class
;
5993 migrate_dead_tasks(cpu
);
5994 spin_unlock_irq(&rq
->lock
);
5996 migrate_nr_uninterruptible(rq
);
5997 BUG_ON(rq
->nr_running
!= 0);
6000 * No need to migrate the tasks: it was best-effort if
6001 * they didn't take sched_hotcpu_mutex. Just wake up
6004 spin_lock_irq(&rq
->lock
);
6005 while (!list_empty(&rq
->migration_queue
)) {
6006 struct migration_req
*req
;
6008 req
= list_entry(rq
->migration_queue
.next
,
6009 struct migration_req
, list
);
6010 list_del_init(&req
->list
);
6011 complete(&req
->done
);
6013 spin_unlock_irq(&rq
->lock
);
6017 case CPU_DYING_FROZEN
:
6018 /* Update our root-domain */
6020 spin_lock_irqsave(&rq
->lock
, flags
);
6022 BUG_ON(!cpu_isset(cpu
, rq
->rd
->span
));
6023 cpu_clear(cpu
, rq
->rd
->online
);
6025 spin_unlock_irqrestore(&rq
->lock
, flags
);
6032 /* Register at highest priority so that task migration (migrate_all_tasks)
6033 * happens before everything else.
6035 static struct notifier_block __cpuinitdata migration_notifier
= {
6036 .notifier_call
= migration_call
,
6040 void __init
migration_init(void)
6042 void *cpu
= (void *)(long)smp_processor_id();
6045 /* Start one for the boot CPU: */
6046 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
6047 BUG_ON(err
== NOTIFY_BAD
);
6048 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
6049 register_cpu_notifier(&migration_notifier
);
6055 /* Number of possible processor ids */
6056 int nr_cpu_ids __read_mostly
= NR_CPUS
;
6057 EXPORT_SYMBOL(nr_cpu_ids
);
6059 #ifdef CONFIG_SCHED_DEBUG
6061 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
)
6063 struct sched_group
*group
= sd
->groups
;
6064 cpumask_t groupmask
;
6067 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
6068 cpus_clear(groupmask
);
6070 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
6072 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
6073 printk("does not load-balance\n");
6075 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
6080 printk(KERN_CONT
"span %s\n", str
);
6082 if (!cpu_isset(cpu
, sd
->span
)) {
6083 printk(KERN_ERR
"ERROR: domain->span does not contain "
6086 if (!cpu_isset(cpu
, group
->cpumask
)) {
6087 printk(KERN_ERR
"ERROR: domain->groups does not contain"
6091 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
6095 printk(KERN_ERR
"ERROR: group is NULL\n");
6099 if (!group
->__cpu_power
) {
6100 printk(KERN_CONT
"\n");
6101 printk(KERN_ERR
"ERROR: domain->cpu_power not "
6106 if (!cpus_weight(group
->cpumask
)) {
6107 printk(KERN_CONT
"\n");
6108 printk(KERN_ERR
"ERROR: empty group\n");
6112 if (cpus_intersects(groupmask
, group
->cpumask
)) {
6113 printk(KERN_CONT
"\n");
6114 printk(KERN_ERR
"ERROR: repeated CPUs\n");
6118 cpus_or(groupmask
, groupmask
, group
->cpumask
);
6120 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
6121 printk(KERN_CONT
" %s", str
);
6123 group
= group
->next
;
6124 } while (group
!= sd
->groups
);
6125 printk(KERN_CONT
"\n");
6127 if (!cpus_equal(sd
->span
, groupmask
))
6128 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
6130 if (sd
->parent
&& !cpus_subset(groupmask
, sd
->parent
->span
))
6131 printk(KERN_ERR
"ERROR: parent span is not a superset "
6132 "of domain->span\n");
6136 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
6141 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
6145 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
6148 if (sched_domain_debug_one(sd
, cpu
, level
))
6157 # define sched_domain_debug(sd, cpu) do { } while (0)
6160 static int sd_degenerate(struct sched_domain
*sd
)
6162 if (cpus_weight(sd
->span
) == 1)
6165 /* Following flags need at least 2 groups */
6166 if (sd
->flags
& (SD_LOAD_BALANCE
|
6167 SD_BALANCE_NEWIDLE
|
6171 SD_SHARE_PKG_RESOURCES
)) {
6172 if (sd
->groups
!= sd
->groups
->next
)
6176 /* Following flags don't use groups */
6177 if (sd
->flags
& (SD_WAKE_IDLE
|
6186 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
6188 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
6190 if (sd_degenerate(parent
))
6193 if (!cpus_equal(sd
->span
, parent
->span
))
6196 /* Does parent contain flags not in child? */
6197 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
6198 if (cflags
& SD_WAKE_AFFINE
)
6199 pflags
&= ~SD_WAKE_BALANCE
;
6200 /* Flags needing groups don't count if only 1 group in parent */
6201 if (parent
->groups
== parent
->groups
->next
) {
6202 pflags
&= ~(SD_LOAD_BALANCE
|
6203 SD_BALANCE_NEWIDLE
|
6207 SD_SHARE_PKG_RESOURCES
);
6209 if (~cflags
& pflags
)
6215 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
6217 unsigned long flags
;
6218 const struct sched_class
*class;
6220 spin_lock_irqsave(&rq
->lock
, flags
);
6223 struct root_domain
*old_rd
= rq
->rd
;
6225 for (class = sched_class_highest
; class; class = class->next
) {
6226 if (class->leave_domain
)
6227 class->leave_domain(rq
);
6230 cpu_clear(rq
->cpu
, old_rd
->span
);
6231 cpu_clear(rq
->cpu
, old_rd
->online
);
6233 if (atomic_dec_and_test(&old_rd
->refcount
))
6237 atomic_inc(&rd
->refcount
);
6240 cpu_set(rq
->cpu
, rd
->span
);
6241 if (cpu_isset(rq
->cpu
, cpu_online_map
))
6242 cpu_set(rq
->cpu
, rd
->online
);
6244 for (class = sched_class_highest
; class; class = class->next
) {
6245 if (class->join_domain
)
6246 class->join_domain(rq
);
6249 spin_unlock_irqrestore(&rq
->lock
, flags
);
6252 static void init_rootdomain(struct root_domain
*rd
)
6254 memset(rd
, 0, sizeof(*rd
));
6256 cpus_clear(rd
->span
);
6257 cpus_clear(rd
->online
);
6260 static void init_defrootdomain(void)
6262 init_rootdomain(&def_root_domain
);
6263 atomic_set(&def_root_domain
.refcount
, 1);
6266 static struct root_domain
*alloc_rootdomain(void)
6268 struct root_domain
*rd
;
6270 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
6274 init_rootdomain(rd
);
6280 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6281 * hold the hotplug lock.
6284 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
6286 struct rq
*rq
= cpu_rq(cpu
);
6287 struct sched_domain
*tmp
;
6289 /* Remove the sched domains which do not contribute to scheduling. */
6290 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
6291 struct sched_domain
*parent
= tmp
->parent
;
6294 if (sd_parent_degenerate(tmp
, parent
)) {
6295 tmp
->parent
= parent
->parent
;
6297 parent
->parent
->child
= tmp
;
6301 if (sd
&& sd_degenerate(sd
)) {
6307 sched_domain_debug(sd
, cpu
);
6309 rq_attach_root(rq
, rd
);
6310 rcu_assign_pointer(rq
->sd
, sd
);
6313 /* cpus with isolated domains */
6314 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
6316 /* Setup the mask of cpus configured for isolated domains */
6317 static int __init
isolated_cpu_setup(char *str
)
6319 int ints
[NR_CPUS
], i
;
6321 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
6322 cpus_clear(cpu_isolated_map
);
6323 for (i
= 1; i
<= ints
[0]; i
++)
6324 if (ints
[i
] < NR_CPUS
)
6325 cpu_set(ints
[i
], cpu_isolated_map
);
6329 __setup("isolcpus=", isolated_cpu_setup
);
6332 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
6333 * to a function which identifies what group(along with sched group) a CPU
6334 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
6335 * (due to the fact that we keep track of groups covered with a cpumask_t).
6337 * init_sched_build_groups will build a circular linked list of the groups
6338 * covered by the given span, and will set each group's ->cpumask correctly,
6339 * and ->cpu_power to 0.
6342 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
6343 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
6344 struct sched_group
**sg
))
6346 struct sched_group
*first
= NULL
, *last
= NULL
;
6347 cpumask_t covered
= CPU_MASK_NONE
;
6350 for_each_cpu_mask(i
, span
) {
6351 struct sched_group
*sg
;
6352 int group
= group_fn(i
, cpu_map
, &sg
);
6355 if (cpu_isset(i
, covered
))
6358 sg
->cpumask
= CPU_MASK_NONE
;
6359 sg
->__cpu_power
= 0;
6361 for_each_cpu_mask(j
, span
) {
6362 if (group_fn(j
, cpu_map
, NULL
) != group
)
6365 cpu_set(j
, covered
);
6366 cpu_set(j
, sg
->cpumask
);
6377 #define SD_NODES_PER_DOMAIN 16
6382 * find_next_best_node - find the next node to include in a sched_domain
6383 * @node: node whose sched_domain we're building
6384 * @used_nodes: nodes already in the sched_domain
6386 * Find the next node to include in a given scheduling domain. Simply
6387 * finds the closest node not already in the @used_nodes map.
6389 * Should use nodemask_t.
6391 static int find_next_best_node(int node
, unsigned long *used_nodes
)
6393 int i
, n
, val
, min_val
, best_node
= 0;
6397 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6398 /* Start at @node */
6399 n
= (node
+ i
) % MAX_NUMNODES
;
6401 if (!nr_cpus_node(n
))
6404 /* Skip already used nodes */
6405 if (test_bit(n
, used_nodes
))
6408 /* Simple min distance search */
6409 val
= node_distance(node
, n
);
6411 if (val
< min_val
) {
6417 set_bit(best_node
, used_nodes
);
6422 * sched_domain_node_span - get a cpumask for a node's sched_domain
6423 * @node: node whose cpumask we're constructing
6424 * @size: number of nodes to include in this span
6426 * Given a node, construct a good cpumask for its sched_domain to span. It
6427 * should be one that prevents unnecessary balancing, but also spreads tasks
6430 static cpumask_t
sched_domain_node_span(int node
)
6432 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
6433 cpumask_t span
, nodemask
;
6437 bitmap_zero(used_nodes
, MAX_NUMNODES
);
6439 nodemask
= node_to_cpumask(node
);
6440 cpus_or(span
, span
, nodemask
);
6441 set_bit(node
, used_nodes
);
6443 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6444 int next_node
= find_next_best_node(node
, used_nodes
);
6446 nodemask
= node_to_cpumask(next_node
);
6447 cpus_or(span
, span
, nodemask
);
6454 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
6457 * SMT sched-domains:
6459 #ifdef CONFIG_SCHED_SMT
6460 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
6461 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6464 cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6467 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6473 * multi-core sched-domains:
6475 #ifdef CONFIG_SCHED_MC
6476 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6477 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6480 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6482 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6485 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6486 cpus_and(mask
, mask
, *cpu_map
);
6487 group
= first_cpu(mask
);
6489 *sg
= &per_cpu(sched_group_core
, group
);
6492 #elif defined(CONFIG_SCHED_MC)
6494 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6497 *sg
= &per_cpu(sched_group_core
, cpu
);
6502 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6503 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6506 cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6509 #ifdef CONFIG_SCHED_MC
6510 cpumask_t mask
= cpu_coregroup_map(cpu
);
6511 cpus_and(mask
, mask
, *cpu_map
);
6512 group
= first_cpu(mask
);
6513 #elif defined(CONFIG_SCHED_SMT)
6514 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6515 cpus_and(mask
, mask
, *cpu_map
);
6516 group
= first_cpu(mask
);
6521 *sg
= &per_cpu(sched_group_phys
, group
);
6527 * The init_sched_build_groups can't handle what we want to do with node
6528 * groups, so roll our own. Now each node has its own list of groups which
6529 * gets dynamically allocated.
6531 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6532 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6534 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6535 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6537 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6538 struct sched_group
**sg
)
6540 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6543 cpus_and(nodemask
, nodemask
, *cpu_map
);
6544 group
= first_cpu(nodemask
);
6547 *sg
= &per_cpu(sched_group_allnodes
, group
);
6551 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6553 struct sched_group
*sg
= group_head
;
6559 for_each_cpu_mask(j
, sg
->cpumask
) {
6560 struct sched_domain
*sd
;
6562 sd
= &per_cpu(phys_domains
, j
);
6563 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6565 * Only add "power" once for each
6571 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
6574 } while (sg
!= group_head
);
6579 /* Free memory allocated for various sched_group structures */
6580 static void free_sched_groups(const cpumask_t
*cpu_map
)
6584 for_each_cpu_mask(cpu
, *cpu_map
) {
6585 struct sched_group
**sched_group_nodes
6586 = sched_group_nodes_bycpu
[cpu
];
6588 if (!sched_group_nodes
)
6591 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6592 cpumask_t nodemask
= node_to_cpumask(i
);
6593 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6595 cpus_and(nodemask
, nodemask
, *cpu_map
);
6596 if (cpus_empty(nodemask
))
6606 if (oldsg
!= sched_group_nodes
[i
])
6609 kfree(sched_group_nodes
);
6610 sched_group_nodes_bycpu
[cpu
] = NULL
;
6614 static void free_sched_groups(const cpumask_t
*cpu_map
)
6620 * Initialize sched groups cpu_power.
6622 * cpu_power indicates the capacity of sched group, which is used while
6623 * distributing the load between different sched groups in a sched domain.
6624 * Typically cpu_power for all the groups in a sched domain will be same unless
6625 * there are asymmetries in the topology. If there are asymmetries, group
6626 * having more cpu_power will pickup more load compared to the group having
6629 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6630 * the maximum number of tasks a group can handle in the presence of other idle
6631 * or lightly loaded groups in the same sched domain.
6633 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6635 struct sched_domain
*child
;
6636 struct sched_group
*group
;
6638 WARN_ON(!sd
|| !sd
->groups
);
6640 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6645 sd
->groups
->__cpu_power
= 0;
6648 * For perf policy, if the groups in child domain share resources
6649 * (for example cores sharing some portions of the cache hierarchy
6650 * or SMT), then set this domain groups cpu_power such that each group
6651 * can handle only one task, when there are other idle groups in the
6652 * same sched domain.
6654 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6656 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6657 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
6662 * add cpu_power of each child group to this groups cpu_power
6664 group
= child
->groups
;
6666 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
6667 group
= group
->next
;
6668 } while (group
!= child
->groups
);
6672 * Build sched domains for a given set of cpus and attach the sched domains
6673 * to the individual cpus
6675 static int build_sched_domains(const cpumask_t
*cpu_map
)
6678 struct root_domain
*rd
;
6680 struct sched_group
**sched_group_nodes
= NULL
;
6681 int sd_allnodes
= 0;
6684 * Allocate the per-node list of sched groups
6686 sched_group_nodes
= kcalloc(MAX_NUMNODES
, sizeof(struct sched_group
*),
6688 if (!sched_group_nodes
) {
6689 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6692 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6695 rd
= alloc_rootdomain();
6697 printk(KERN_WARNING
"Cannot alloc root domain\n");
6702 * Set up domains for cpus specified by the cpu_map.
6704 for_each_cpu_mask(i
, *cpu_map
) {
6705 struct sched_domain
*sd
= NULL
, *p
;
6706 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6708 cpus_and(nodemask
, nodemask
, *cpu_map
);
6711 if (cpus_weight(*cpu_map
) >
6712 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6713 sd
= &per_cpu(allnodes_domains
, i
);
6714 *sd
= SD_ALLNODES_INIT
;
6715 sd
->span
= *cpu_map
;
6716 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6722 sd
= &per_cpu(node_domains
, i
);
6724 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6728 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6732 sd
= &per_cpu(phys_domains
, i
);
6734 sd
->span
= nodemask
;
6738 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6740 #ifdef CONFIG_SCHED_MC
6742 sd
= &per_cpu(core_domains
, i
);
6744 sd
->span
= cpu_coregroup_map(i
);
6745 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6748 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6751 #ifdef CONFIG_SCHED_SMT
6753 sd
= &per_cpu(cpu_domains
, i
);
6754 *sd
= SD_SIBLING_INIT
;
6755 sd
->span
= per_cpu(cpu_sibling_map
, i
);
6756 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6759 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6763 #ifdef CONFIG_SCHED_SMT
6764 /* Set up CPU (sibling) groups */
6765 for_each_cpu_mask(i
, *cpu_map
) {
6766 cpumask_t this_sibling_map
= per_cpu(cpu_sibling_map
, i
);
6767 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6768 if (i
!= first_cpu(this_sibling_map
))
6771 init_sched_build_groups(this_sibling_map
, cpu_map
,
6776 #ifdef CONFIG_SCHED_MC
6777 /* Set up multi-core groups */
6778 for_each_cpu_mask(i
, *cpu_map
) {
6779 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6780 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6781 if (i
!= first_cpu(this_core_map
))
6783 init_sched_build_groups(this_core_map
, cpu_map
,
6784 &cpu_to_core_group
);
6788 /* Set up physical groups */
6789 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6790 cpumask_t nodemask
= node_to_cpumask(i
);
6792 cpus_and(nodemask
, nodemask
, *cpu_map
);
6793 if (cpus_empty(nodemask
))
6796 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6800 /* Set up node groups */
6802 init_sched_build_groups(*cpu_map
, cpu_map
,
6803 &cpu_to_allnodes_group
);
6805 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6806 /* Set up node groups */
6807 struct sched_group
*sg
, *prev
;
6808 cpumask_t nodemask
= node_to_cpumask(i
);
6809 cpumask_t domainspan
;
6810 cpumask_t covered
= CPU_MASK_NONE
;
6813 cpus_and(nodemask
, nodemask
, *cpu_map
);
6814 if (cpus_empty(nodemask
)) {
6815 sched_group_nodes
[i
] = NULL
;
6819 domainspan
= sched_domain_node_span(i
);
6820 cpus_and(domainspan
, domainspan
, *cpu_map
);
6822 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6824 printk(KERN_WARNING
"Can not alloc domain group for "
6828 sched_group_nodes
[i
] = sg
;
6829 for_each_cpu_mask(j
, nodemask
) {
6830 struct sched_domain
*sd
;
6832 sd
= &per_cpu(node_domains
, j
);
6835 sg
->__cpu_power
= 0;
6836 sg
->cpumask
= nodemask
;
6838 cpus_or(covered
, covered
, nodemask
);
6841 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6842 cpumask_t tmp
, notcovered
;
6843 int n
= (i
+ j
) % MAX_NUMNODES
;
6845 cpus_complement(notcovered
, covered
);
6846 cpus_and(tmp
, notcovered
, *cpu_map
);
6847 cpus_and(tmp
, tmp
, domainspan
);
6848 if (cpus_empty(tmp
))
6851 nodemask
= node_to_cpumask(n
);
6852 cpus_and(tmp
, tmp
, nodemask
);
6853 if (cpus_empty(tmp
))
6856 sg
= kmalloc_node(sizeof(struct sched_group
),
6860 "Can not alloc domain group for node %d\n", j
);
6863 sg
->__cpu_power
= 0;
6865 sg
->next
= prev
->next
;
6866 cpus_or(covered
, covered
, tmp
);
6873 /* Calculate CPU power for physical packages and nodes */
6874 #ifdef CONFIG_SCHED_SMT
6875 for_each_cpu_mask(i
, *cpu_map
) {
6876 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6878 init_sched_groups_power(i
, sd
);
6881 #ifdef CONFIG_SCHED_MC
6882 for_each_cpu_mask(i
, *cpu_map
) {
6883 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6885 init_sched_groups_power(i
, sd
);
6889 for_each_cpu_mask(i
, *cpu_map
) {
6890 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6892 init_sched_groups_power(i
, sd
);
6896 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6897 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6900 struct sched_group
*sg
;
6902 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6903 init_numa_sched_groups_power(sg
);
6907 /* Attach the domains */
6908 for_each_cpu_mask(i
, *cpu_map
) {
6909 struct sched_domain
*sd
;
6910 #ifdef CONFIG_SCHED_SMT
6911 sd
= &per_cpu(cpu_domains
, i
);
6912 #elif defined(CONFIG_SCHED_MC)
6913 sd
= &per_cpu(core_domains
, i
);
6915 sd
= &per_cpu(phys_domains
, i
);
6917 cpu_attach_domain(sd
, rd
, i
);
6924 free_sched_groups(cpu_map
);
6929 static cpumask_t
*doms_cur
; /* current sched domains */
6930 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6933 * Special case: If a kmalloc of a doms_cur partition (array of
6934 * cpumask_t) fails, then fallback to a single sched domain,
6935 * as determined by the single cpumask_t fallback_doms.
6937 static cpumask_t fallback_doms
;
6939 void __attribute__((weak
)) arch_update_cpu_topology(void)
6944 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6945 * For now this just excludes isolated cpus, but could be used to
6946 * exclude other special cases in the future.
6948 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6952 arch_update_cpu_topology();
6954 doms_cur
= kmalloc(sizeof(cpumask_t
), GFP_KERNEL
);
6956 doms_cur
= &fallback_doms
;
6957 cpus_andnot(*doms_cur
, *cpu_map
, cpu_isolated_map
);
6958 err
= build_sched_domains(doms_cur
);
6959 register_sched_domain_sysctl();
6964 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6966 free_sched_groups(cpu_map
);
6970 * Detach sched domains from a group of cpus specified in cpu_map
6971 * These cpus will now be attached to the NULL domain
6973 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6977 unregister_sched_domain_sysctl();
6979 for_each_cpu_mask(i
, *cpu_map
)
6980 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6981 synchronize_sched();
6982 arch_destroy_sched_domains(cpu_map
);
6986 * Partition sched domains as specified by the 'ndoms_new'
6987 * cpumasks in the array doms_new[] of cpumasks. This compares
6988 * doms_new[] to the current sched domain partitioning, doms_cur[].
6989 * It destroys each deleted domain and builds each new domain.
6991 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
6992 * The masks don't intersect (don't overlap.) We should setup one
6993 * sched domain for each mask. CPUs not in any of the cpumasks will
6994 * not be load balanced. If the same cpumask appears both in the
6995 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6998 * The passed in 'doms_new' should be kmalloc'd. This routine takes
6999 * ownership of it and will kfree it when done with it. If the caller
7000 * failed the kmalloc call, then it can pass in doms_new == NULL,
7001 * and partition_sched_domains() will fallback to the single partition
7004 * Call with hotplug lock held
7006 void partition_sched_domains(int ndoms_new
, cpumask_t
*doms_new
)
7012 /* always unregister in case we don't destroy any domains */
7013 unregister_sched_domain_sysctl();
7015 if (doms_new
== NULL
) {
7017 doms_new
= &fallback_doms
;
7018 cpus_andnot(doms_new
[0], cpu_online_map
, cpu_isolated_map
);
7021 /* Destroy deleted domains */
7022 for (i
= 0; i
< ndoms_cur
; i
++) {
7023 for (j
= 0; j
< ndoms_new
; j
++) {
7024 if (cpus_equal(doms_cur
[i
], doms_new
[j
]))
7027 /* no match - a current sched domain not in new doms_new[] */
7028 detach_destroy_domains(doms_cur
+ i
);
7033 /* Build new domains */
7034 for (i
= 0; i
< ndoms_new
; i
++) {
7035 for (j
= 0; j
< ndoms_cur
; j
++) {
7036 if (cpus_equal(doms_new
[i
], doms_cur
[j
]))
7039 /* no match - add a new doms_new */
7040 build_sched_domains(doms_new
+ i
);
7045 /* Remember the new sched domains */
7046 if (doms_cur
!= &fallback_doms
)
7048 doms_cur
= doms_new
;
7049 ndoms_cur
= ndoms_new
;
7051 register_sched_domain_sysctl();
7056 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
7057 int arch_reinit_sched_domains(void)
7062 detach_destroy_domains(&cpu_online_map
);
7063 err
= arch_init_sched_domains(&cpu_online_map
);
7069 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
7073 if (buf
[0] != '0' && buf
[0] != '1')
7077 sched_smt_power_savings
= (buf
[0] == '1');
7079 sched_mc_power_savings
= (buf
[0] == '1');
7081 ret
= arch_reinit_sched_domains();
7083 return ret
? ret
: count
;
7086 #ifdef CONFIG_SCHED_MC
7087 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
7089 return sprintf(page
, "%u\n", sched_mc_power_savings
);
7091 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
7092 const char *buf
, size_t count
)
7094 return sched_power_savings_store(buf
, count
, 0);
7096 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
7097 sched_mc_power_savings_store
);
7100 #ifdef CONFIG_SCHED_SMT
7101 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
7103 return sprintf(page
, "%u\n", sched_smt_power_savings
);
7105 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
7106 const char *buf
, size_t count
)
7108 return sched_power_savings_store(buf
, count
, 1);
7110 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
7111 sched_smt_power_savings_store
);
7114 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
7118 #ifdef CONFIG_SCHED_SMT
7120 err
= sysfs_create_file(&cls
->kset
.kobj
,
7121 &attr_sched_smt_power_savings
.attr
);
7123 #ifdef CONFIG_SCHED_MC
7124 if (!err
&& mc_capable())
7125 err
= sysfs_create_file(&cls
->kset
.kobj
,
7126 &attr_sched_mc_power_savings
.attr
);
7133 * Force a reinitialization of the sched domains hierarchy. The domains
7134 * and groups cannot be updated in place without racing with the balancing
7135 * code, so we temporarily attach all running cpus to the NULL domain
7136 * which will prevent rebalancing while the sched domains are recalculated.
7138 static int update_sched_domains(struct notifier_block
*nfb
,
7139 unsigned long action
, void *hcpu
)
7142 case CPU_UP_PREPARE
:
7143 case CPU_UP_PREPARE_FROZEN
:
7144 case CPU_DOWN_PREPARE
:
7145 case CPU_DOWN_PREPARE_FROZEN
:
7146 detach_destroy_domains(&cpu_online_map
);
7149 case CPU_UP_CANCELED
:
7150 case CPU_UP_CANCELED_FROZEN
:
7151 case CPU_DOWN_FAILED
:
7152 case CPU_DOWN_FAILED_FROZEN
:
7154 case CPU_ONLINE_FROZEN
:
7156 case CPU_DEAD_FROZEN
:
7158 * Fall through and re-initialise the domains.
7165 /* The hotplug lock is already held by cpu_up/cpu_down */
7166 arch_init_sched_domains(&cpu_online_map
);
7171 void __init
sched_init_smp(void)
7173 cpumask_t non_isolated_cpus
;
7176 arch_init_sched_domains(&cpu_online_map
);
7177 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
7178 if (cpus_empty(non_isolated_cpus
))
7179 cpu_set(smp_processor_id(), non_isolated_cpus
);
7181 /* XXX: Theoretical race here - CPU may be hotplugged now */
7182 hotcpu_notifier(update_sched_domains
, 0);
7184 /* Move init over to a non-isolated CPU */
7185 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
7187 sched_init_granularity();
7190 void __init
sched_init_smp(void)
7192 sched_init_granularity();
7194 #endif /* CONFIG_SMP */
7196 int in_sched_functions(unsigned long addr
)
7198 return in_lock_functions(addr
) ||
7199 (addr
>= (unsigned long)__sched_text_start
7200 && addr
< (unsigned long)__sched_text_end
);
7203 static void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
7205 cfs_rq
->tasks_timeline
= RB_ROOT
;
7206 #ifdef CONFIG_FAIR_GROUP_SCHED
7209 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
7212 static void init_rt_rq(struct rt_rq
*rt_rq
, struct rq
*rq
)
7214 struct rt_prio_array
*array
;
7217 array
= &rt_rq
->active
;
7218 for (i
= 0; i
< MAX_RT_PRIO
; i
++) {
7219 INIT_LIST_HEAD(array
->queue
+ i
);
7220 __clear_bit(i
, array
->bitmap
);
7222 /* delimiter for bitsearch: */
7223 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
7225 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
7226 rt_rq
->highest_prio
= MAX_RT_PRIO
;
7229 rt_rq
->rt_nr_migratory
= 0;
7230 rt_rq
->overloaded
= 0;
7234 rt_rq
->rt_throttled
= 0;
7236 #ifdef CONFIG_RT_GROUP_SCHED
7237 rt_rq
->rt_nr_boosted
= 0;
7242 #ifdef CONFIG_FAIR_GROUP_SCHED
7243 static void init_tg_cfs_entry(struct rq
*rq
, struct task_group
*tg
,
7244 struct cfs_rq
*cfs_rq
, struct sched_entity
*se
,
7247 tg
->cfs_rq
[cpu
] = cfs_rq
;
7248 init_cfs_rq(cfs_rq
, rq
);
7251 list_add(&cfs_rq
->leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
7254 se
->cfs_rq
= &rq
->cfs
;
7256 se
->load
.weight
= tg
->shares
;
7257 se
->load
.inv_weight
= div64_64(1ULL<<32, se
->load
.weight
);
7262 #ifdef CONFIG_RT_GROUP_SCHED
7263 static void init_tg_rt_entry(struct rq
*rq
, struct task_group
*tg
,
7264 struct rt_rq
*rt_rq
, struct sched_rt_entity
*rt_se
,
7267 tg
->rt_rq
[cpu
] = rt_rq
;
7268 init_rt_rq(rt_rq
, rq
);
7270 rt_rq
->rt_se
= rt_se
;
7272 list_add(&rt_rq
->leaf_rt_rq_list
, &rq
->leaf_rt_rq_list
);
7274 tg
->rt_se
[cpu
] = rt_se
;
7275 rt_se
->rt_rq
= &rq
->rt
;
7276 rt_se
->my_q
= rt_rq
;
7277 rt_se
->parent
= NULL
;
7278 INIT_LIST_HEAD(&rt_se
->run_list
);
7282 void __init
sched_init(void)
7284 int highest_cpu
= 0;
7288 init_defrootdomain();
7291 #ifdef CONFIG_GROUP_SCHED
7292 list_add(&init_task_group
.list
, &task_groups
);
7295 for_each_possible_cpu(i
) {
7299 spin_lock_init(&rq
->lock
);
7300 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
7303 update_last_tick_seen(rq
);
7304 init_cfs_rq(&rq
->cfs
, rq
);
7305 init_rt_rq(&rq
->rt
, rq
);
7306 #ifdef CONFIG_FAIR_GROUP_SCHED
7307 init_task_group
.shares
= init_task_group_load
;
7308 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
7309 init_tg_cfs_entry(rq
, &init_task_group
,
7310 &per_cpu(init_cfs_rq
, i
),
7311 &per_cpu(init_sched_entity
, i
), i
, 1);
7314 #ifdef CONFIG_RT_GROUP_SCHED
7315 init_task_group
.rt_runtime
=
7316 sysctl_sched_rt_runtime
* NSEC_PER_USEC
;
7317 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
7318 init_tg_rt_entry(rq
, &init_task_group
,
7319 &per_cpu(init_rt_rq
, i
),
7320 &per_cpu(init_sched_rt_entity
, i
), i
, 1);
7322 rq
->rt_period_expire
= 0;
7323 rq
->rt_throttled
= 0;
7325 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7326 rq
->cpu_load
[j
] = 0;
7330 rq
->active_balance
= 0;
7331 rq
->next_balance
= jiffies
;
7334 rq
->migration_thread
= NULL
;
7335 INIT_LIST_HEAD(&rq
->migration_queue
);
7336 rq_attach_root(rq
, &def_root_domain
);
7339 atomic_set(&rq
->nr_iowait
, 0);
7343 set_load_weight(&init_task
);
7345 #ifdef CONFIG_PREEMPT_NOTIFIERS
7346 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7350 nr_cpu_ids
= highest_cpu
+ 1;
7351 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
7354 #ifdef CONFIG_RT_MUTEXES
7355 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
7359 * The boot idle thread does lazy MMU switching as well:
7361 atomic_inc(&init_mm
.mm_count
);
7362 enter_lazy_tlb(&init_mm
, current
);
7365 * Make us the idle thread. Technically, schedule() should not be
7366 * called from this thread, however somewhere below it might be,
7367 * but because we are the idle thread, we just pick up running again
7368 * when this runqueue becomes "idle".
7370 init_idle(current
, smp_processor_id());
7372 * During early bootup we pretend to be a normal task:
7374 current
->sched_class
= &fair_sched_class
;
7376 scheduler_running
= 1;
7379 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
7380 void __might_sleep(char *file
, int line
)
7383 static unsigned long prev_jiffy
; /* ratelimiting */
7385 if ((in_atomic() || irqs_disabled()) &&
7386 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
7387 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7389 prev_jiffy
= jiffies
;
7390 printk(KERN_ERR
"BUG: sleeping function called from invalid"
7391 " context at %s:%d\n", file
, line
);
7392 printk("in_atomic():%d, irqs_disabled():%d\n",
7393 in_atomic(), irqs_disabled());
7394 debug_show_held_locks(current
);
7395 if (irqs_disabled())
7396 print_irqtrace_events(current
);
7401 EXPORT_SYMBOL(__might_sleep
);
7404 #ifdef CONFIG_MAGIC_SYSRQ
7405 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7408 update_rq_clock(rq
);
7409 on_rq
= p
->se
.on_rq
;
7411 deactivate_task(rq
, p
, 0);
7412 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
7414 activate_task(rq
, p
, 0);
7415 resched_task(rq
->curr
);
7419 void normalize_rt_tasks(void)
7421 struct task_struct
*g
, *p
;
7422 unsigned long flags
;
7425 read_lock_irqsave(&tasklist_lock
, flags
);
7426 do_each_thread(g
, p
) {
7428 * Only normalize user tasks:
7433 p
->se
.exec_start
= 0;
7434 #ifdef CONFIG_SCHEDSTATS
7435 p
->se
.wait_start
= 0;
7436 p
->se
.sleep_start
= 0;
7437 p
->se
.block_start
= 0;
7439 task_rq(p
)->clock
= 0;
7443 * Renice negative nice level userspace
7446 if (TASK_NICE(p
) < 0 && p
->mm
)
7447 set_user_nice(p
, 0);
7451 spin_lock(&p
->pi_lock
);
7452 rq
= __task_rq_lock(p
);
7454 normalize_task(rq
, p
);
7456 __task_rq_unlock(rq
);
7457 spin_unlock(&p
->pi_lock
);
7458 } while_each_thread(g
, p
);
7460 read_unlock_irqrestore(&tasklist_lock
, flags
);
7463 #endif /* CONFIG_MAGIC_SYSRQ */
7467 * These functions are only useful for the IA64 MCA handling.
7469 * They can only be called when the whole system has been
7470 * stopped - every CPU needs to be quiescent, and no scheduling
7471 * activity can take place. Using them for anything else would
7472 * be a serious bug, and as a result, they aren't even visible
7473 * under any other configuration.
7477 * curr_task - return the current task for a given cpu.
7478 * @cpu: the processor in question.
7480 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7482 struct task_struct
*curr_task(int cpu
)
7484 return cpu_curr(cpu
);
7488 * set_curr_task - set the current task for a given cpu.
7489 * @cpu: the processor in question.
7490 * @p: the task pointer to set.
7492 * Description: This function must only be used when non-maskable interrupts
7493 * are serviced on a separate stack. It allows the architecture to switch the
7494 * notion of the current task on a cpu in a non-blocking manner. This function
7495 * must be called with all CPU's synchronized, and interrupts disabled, the
7496 * and caller must save the original value of the current task (see
7497 * curr_task() above) and restore that value before reenabling interrupts and
7498 * re-starting the system.
7500 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7502 void set_curr_task(int cpu
, struct task_struct
*p
)
7509 #ifdef CONFIG_GROUP_SCHED
7511 #ifdef CONFIG_FAIR_GROUP_SCHED
7512 static void free_fair_sched_group(struct task_group
*tg
)
7516 for_each_possible_cpu(i
) {
7518 kfree(tg
->cfs_rq
[i
]);
7527 static int alloc_fair_sched_group(struct task_group
*tg
)
7529 struct cfs_rq
*cfs_rq
;
7530 struct sched_entity
*se
;
7534 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * NR_CPUS
, GFP_KERNEL
);
7537 tg
->se
= kzalloc(sizeof(se
) * NR_CPUS
, GFP_KERNEL
);
7541 tg
->shares
= NICE_0_LOAD
;
7543 for_each_possible_cpu(i
) {
7546 cfs_rq
= kmalloc_node(sizeof(struct cfs_rq
),
7547 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7551 se
= kmalloc_node(sizeof(struct sched_entity
),
7552 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7556 init_tg_cfs_entry(rq
, tg
, cfs_rq
, se
, i
, 0);
7565 static inline void register_fair_sched_group(struct task_group
*tg
, int cpu
)
7567 list_add_rcu(&tg
->cfs_rq
[cpu
]->leaf_cfs_rq_list
,
7568 &cpu_rq(cpu
)->leaf_cfs_rq_list
);
7571 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
7573 list_del_rcu(&tg
->cfs_rq
[cpu
]->leaf_cfs_rq_list
);
7576 static inline void free_fair_sched_group(struct task_group
*tg
)
7580 static inline int alloc_fair_sched_group(struct task_group
*tg
)
7585 static inline void register_fair_sched_group(struct task_group
*tg
, int cpu
)
7589 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
7594 #ifdef CONFIG_RT_GROUP_SCHED
7595 static void free_rt_sched_group(struct task_group
*tg
)
7599 for_each_possible_cpu(i
) {
7601 kfree(tg
->rt_rq
[i
]);
7603 kfree(tg
->rt_se
[i
]);
7610 static int alloc_rt_sched_group(struct task_group
*tg
)
7612 struct rt_rq
*rt_rq
;
7613 struct sched_rt_entity
*rt_se
;
7617 tg
->rt_rq
= kzalloc(sizeof(rt_rq
) * NR_CPUS
, GFP_KERNEL
);
7620 tg
->rt_se
= kzalloc(sizeof(rt_se
) * NR_CPUS
, GFP_KERNEL
);
7626 for_each_possible_cpu(i
) {
7629 rt_rq
= kmalloc_node(sizeof(struct rt_rq
),
7630 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7634 rt_se
= kmalloc_node(sizeof(struct sched_rt_entity
),
7635 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7639 init_tg_rt_entry(rq
, tg
, rt_rq
, rt_se
, i
, 0);
7648 static inline void register_rt_sched_group(struct task_group
*tg
, int cpu
)
7650 list_add_rcu(&tg
->rt_rq
[cpu
]->leaf_rt_rq_list
,
7651 &cpu_rq(cpu
)->leaf_rt_rq_list
);
7654 static inline void unregister_rt_sched_group(struct task_group
*tg
, int cpu
)
7656 list_del_rcu(&tg
->rt_rq
[cpu
]->leaf_rt_rq_list
);
7659 static inline void free_rt_sched_group(struct task_group
*tg
)
7663 static inline int alloc_rt_sched_group(struct task_group
*tg
)
7668 static inline void register_rt_sched_group(struct task_group
*tg
, int cpu
)
7672 static inline void unregister_rt_sched_group(struct task_group
*tg
, int cpu
)
7677 static void free_sched_group(struct task_group
*tg
)
7679 free_fair_sched_group(tg
);
7680 free_rt_sched_group(tg
);
7684 /* allocate runqueue etc for a new task group */
7685 struct task_group
*sched_create_group(void)
7687 struct task_group
*tg
;
7688 unsigned long flags
;
7691 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7693 return ERR_PTR(-ENOMEM
);
7695 if (!alloc_fair_sched_group(tg
))
7698 if (!alloc_rt_sched_group(tg
))
7701 spin_lock_irqsave(&task_group_lock
, flags
);
7702 for_each_possible_cpu(i
) {
7703 register_fair_sched_group(tg
, i
);
7704 register_rt_sched_group(tg
, i
);
7706 list_add_rcu(&tg
->list
, &task_groups
);
7707 spin_unlock_irqrestore(&task_group_lock
, flags
);
7712 free_sched_group(tg
);
7713 return ERR_PTR(-ENOMEM
);
7716 /* rcu callback to free various structures associated with a task group */
7717 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7719 /* now it should be safe to free those cfs_rqs */
7720 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7723 /* Destroy runqueue etc associated with a task group */
7724 void sched_destroy_group(struct task_group
*tg
)
7726 unsigned long flags
;
7729 spin_lock_irqsave(&task_group_lock
, flags
);
7730 for_each_possible_cpu(i
) {
7731 unregister_fair_sched_group(tg
, i
);
7732 unregister_rt_sched_group(tg
, i
);
7734 list_del_rcu(&tg
->list
);
7735 spin_unlock_irqrestore(&task_group_lock
, flags
);
7737 /* wait for possible concurrent references to cfs_rqs complete */
7738 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7741 /* change task's runqueue when it moves between groups.
7742 * The caller of this function should have put the task in its new group
7743 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7744 * reflect its new group.
7746 void sched_move_task(struct task_struct
*tsk
)
7749 unsigned long flags
;
7752 rq
= task_rq_lock(tsk
, &flags
);
7754 update_rq_clock(rq
);
7756 running
= task_current(rq
, tsk
);
7757 on_rq
= tsk
->se
.on_rq
;
7760 dequeue_task(rq
, tsk
, 0);
7761 if (unlikely(running
))
7762 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7764 set_task_rq(tsk
, task_cpu(tsk
));
7766 #ifdef CONFIG_FAIR_GROUP_SCHED
7767 if (tsk
->sched_class
->moved_group
)
7768 tsk
->sched_class
->moved_group(tsk
);
7771 if (unlikely(running
))
7772 tsk
->sched_class
->set_curr_task(rq
);
7774 enqueue_task(rq
, tsk
, 0);
7776 task_rq_unlock(rq
, &flags
);
7779 #ifdef CONFIG_FAIR_GROUP_SCHED
7780 static void set_se_shares(struct sched_entity
*se
, unsigned long shares
)
7782 struct cfs_rq
*cfs_rq
= se
->cfs_rq
;
7783 struct rq
*rq
= cfs_rq
->rq
;
7786 spin_lock_irq(&rq
->lock
);
7790 dequeue_entity(cfs_rq
, se
, 0);
7792 se
->load
.weight
= shares
;
7793 se
->load
.inv_weight
= div64_64((1ULL<<32), shares
);
7796 enqueue_entity(cfs_rq
, se
, 0);
7798 spin_unlock_irq(&rq
->lock
);
7801 static DEFINE_MUTEX(shares_mutex
);
7803 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
7806 unsigned long flags
;
7809 * A weight of 0 or 1 can cause arithmetics problems.
7810 * (The default weight is 1024 - so there's no practical
7811 * limitation from this.)
7816 mutex_lock(&shares_mutex
);
7817 if (tg
->shares
== shares
)
7820 spin_lock_irqsave(&task_group_lock
, flags
);
7821 for_each_possible_cpu(i
)
7822 unregister_fair_sched_group(tg
, i
);
7823 spin_unlock_irqrestore(&task_group_lock
, flags
);
7825 /* wait for any ongoing reference to this group to finish */
7826 synchronize_sched();
7829 * Now we are free to modify the group's share on each cpu
7830 * w/o tripping rebalance_share or load_balance_fair.
7832 tg
->shares
= shares
;
7833 for_each_possible_cpu(i
)
7834 set_se_shares(tg
->se
[i
], shares
);
7837 * Enable load balance activity on this group, by inserting it back on
7838 * each cpu's rq->leaf_cfs_rq_list.
7840 spin_lock_irqsave(&task_group_lock
, flags
);
7841 for_each_possible_cpu(i
)
7842 register_fair_sched_group(tg
, i
);
7843 spin_unlock_irqrestore(&task_group_lock
, flags
);
7845 mutex_unlock(&shares_mutex
);
7849 unsigned long sched_group_shares(struct task_group
*tg
)
7855 #ifdef CONFIG_RT_GROUP_SCHED
7857 * Ensure that the real time constraints are schedulable.
7859 static DEFINE_MUTEX(rt_constraints_mutex
);
7861 static unsigned long to_ratio(u64 period
, u64 runtime
)
7863 if (runtime
== RUNTIME_INF
)
7866 return div64_64(runtime
<< 16, period
);
7869 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7871 struct task_group
*tgi
;
7872 unsigned long total
= 0;
7873 unsigned long global_ratio
=
7874 to_ratio(sysctl_sched_rt_period
,
7875 sysctl_sched_rt_runtime
< 0 ?
7876 RUNTIME_INF
: sysctl_sched_rt_runtime
);
7879 list_for_each_entry_rcu(tgi
, &task_groups
, list
) {
7883 total
+= to_ratio(period
, tgi
->rt_runtime
);
7887 return total
+ to_ratio(period
, runtime
) < global_ratio
;
7890 /* Must be called with tasklist_lock held */
7891 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7893 struct task_struct
*g
, *p
;
7894 do_each_thread(g
, p
) {
7895 if (rt_task(p
) && rt_rq_of_se(&p
->rt
)->tg
== tg
)
7897 } while_each_thread(g
, p
);
7901 int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7903 u64 rt_runtime
, rt_period
;
7906 rt_period
= (u64
)sysctl_sched_rt_period
* NSEC_PER_USEC
;
7907 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7908 if (rt_runtime_us
== -1)
7909 rt_runtime
= RUNTIME_INF
;
7911 mutex_lock(&rt_constraints_mutex
);
7912 read_lock(&tasklist_lock
);
7913 if (rt_runtime_us
== 0 && tg_has_rt_tasks(tg
)) {
7917 if (!__rt_schedulable(tg
, rt_period
, rt_runtime
)) {
7921 tg
->rt_runtime
= rt_runtime
;
7923 read_unlock(&tasklist_lock
);
7924 mutex_unlock(&rt_constraints_mutex
);
7929 long sched_group_rt_runtime(struct task_group
*tg
)
7933 if (tg
->rt_runtime
== RUNTIME_INF
)
7936 rt_runtime_us
= tg
->rt_runtime
;
7937 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7938 return rt_runtime_us
;
7941 #endif /* CONFIG_GROUP_SCHED */
7943 #ifdef CONFIG_CGROUP_SCHED
7945 /* return corresponding task_group object of a cgroup */
7946 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7948 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7949 struct task_group
, css
);
7952 static struct cgroup_subsys_state
*
7953 cpu_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7955 struct task_group
*tg
;
7957 if (!cgrp
->parent
) {
7958 /* This is early initialization for the top cgroup */
7959 init_task_group
.css
.cgroup
= cgrp
;
7960 return &init_task_group
.css
;
7963 /* we support only 1-level deep hierarchical scheduler atm */
7964 if (cgrp
->parent
->parent
)
7965 return ERR_PTR(-EINVAL
);
7967 tg
= sched_create_group();
7969 return ERR_PTR(-ENOMEM
);
7971 /* Bind the cgroup to task_group object we just created */
7972 tg
->css
.cgroup
= cgrp
;
7978 cpu_cgroup_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7980 struct task_group
*tg
= cgroup_tg(cgrp
);
7982 sched_destroy_group(tg
);
7986 cpu_cgroup_can_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
7987 struct task_struct
*tsk
)
7989 #ifdef CONFIG_RT_GROUP_SCHED
7990 /* Don't accept realtime tasks when there is no way for them to run */
7991 if (rt_task(tsk
) && cgroup_tg(cgrp
)->rt_runtime
== 0)
7994 /* We don't support RT-tasks being in separate groups */
7995 if (tsk
->sched_class
!= &fair_sched_class
)
8003 cpu_cgroup_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
8004 struct cgroup
*old_cont
, struct task_struct
*tsk
)
8006 sched_move_task(tsk
);
8009 #ifdef CONFIG_FAIR_GROUP_SCHED
8010 static int cpu_shares_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
8013 return sched_group_set_shares(cgroup_tg(cgrp
), shareval
);
8016 static u64
cpu_shares_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
8018 struct task_group
*tg
= cgroup_tg(cgrp
);
8020 return (u64
) tg
->shares
;
8024 #ifdef CONFIG_RT_GROUP_SCHED
8025 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
8027 const char __user
*userbuf
,
8028 size_t nbytes
, loff_t
*unused_ppos
)
8037 if (nbytes
>= sizeof(buffer
))
8039 if (copy_from_user(buffer
, userbuf
, nbytes
))
8042 buffer
[nbytes
] = 0; /* nul-terminate */
8044 /* strip newline if necessary */
8045 if (nbytes
&& (buffer
[nbytes
-1] == '\n'))
8046 buffer
[nbytes
-1] = 0;
8047 val
= simple_strtoll(buffer
, &end
, 0);
8051 /* Pass to subsystem */
8052 retval
= sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
8058 static ssize_t
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
,
8060 char __user
*buf
, size_t nbytes
,
8064 long val
= sched_group_rt_runtime(cgroup_tg(cgrp
));
8065 int len
= sprintf(tmp
, "%ld\n", val
);
8067 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
8071 static struct cftype cpu_files
[] = {
8072 #ifdef CONFIG_FAIR_GROUP_SCHED
8075 .read_uint
= cpu_shares_read_uint
,
8076 .write_uint
= cpu_shares_write_uint
,
8079 #ifdef CONFIG_RT_GROUP_SCHED
8081 .name
= "rt_runtime_us",
8082 .read
= cpu_rt_runtime_read
,
8083 .write
= cpu_rt_runtime_write
,
8088 static int cpu_cgroup_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8090 return cgroup_add_files(cont
, ss
, cpu_files
, ARRAY_SIZE(cpu_files
));
8093 struct cgroup_subsys cpu_cgroup_subsys
= {
8095 .create
= cpu_cgroup_create
,
8096 .destroy
= cpu_cgroup_destroy
,
8097 .can_attach
= cpu_cgroup_can_attach
,
8098 .attach
= cpu_cgroup_attach
,
8099 .populate
= cpu_cgroup_populate
,
8100 .subsys_id
= cpu_cgroup_subsys_id
,
8104 #endif /* CONFIG_CGROUP_SCHED */
8106 #ifdef CONFIG_CGROUP_CPUACCT
8109 * CPU accounting code for task groups.
8111 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
8112 * (balbir@in.ibm.com).
8115 /* track cpu usage of a group of tasks */
8117 struct cgroup_subsys_state css
;
8118 /* cpuusage holds pointer to a u64-type object on every cpu */
8122 struct cgroup_subsys cpuacct_subsys
;
8124 /* return cpu accounting group corresponding to this container */
8125 static inline struct cpuacct
*cgroup_ca(struct cgroup
*cont
)
8127 return container_of(cgroup_subsys_state(cont
, cpuacct_subsys_id
),
8128 struct cpuacct
, css
);
8131 /* return cpu accounting group to which this task belongs */
8132 static inline struct cpuacct
*task_ca(struct task_struct
*tsk
)
8134 return container_of(task_subsys_state(tsk
, cpuacct_subsys_id
),
8135 struct cpuacct
, css
);
8138 /* create a new cpu accounting group */
8139 static struct cgroup_subsys_state
*cpuacct_create(
8140 struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8142 struct cpuacct
*ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
8145 return ERR_PTR(-ENOMEM
);
8147 ca
->cpuusage
= alloc_percpu(u64
);
8148 if (!ca
->cpuusage
) {
8150 return ERR_PTR(-ENOMEM
);
8156 /* destroy an existing cpu accounting group */
8158 cpuacct_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8160 struct cpuacct
*ca
= cgroup_ca(cont
);
8162 free_percpu(ca
->cpuusage
);
8166 /* return total cpu usage (in nanoseconds) of a group */
8167 static u64
cpuusage_read(struct cgroup
*cont
, struct cftype
*cft
)
8169 struct cpuacct
*ca
= cgroup_ca(cont
);
8170 u64 totalcpuusage
= 0;
8173 for_each_possible_cpu(i
) {
8174 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, i
);
8177 * Take rq->lock to make 64-bit addition safe on 32-bit
8180 spin_lock_irq(&cpu_rq(i
)->lock
);
8181 totalcpuusage
+= *cpuusage
;
8182 spin_unlock_irq(&cpu_rq(i
)->lock
);
8185 return totalcpuusage
;
8188 static struct cftype files
[] = {
8191 .read_uint
= cpuusage_read
,
8195 static int cpuacct_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8197 return cgroup_add_files(cont
, ss
, files
, ARRAY_SIZE(files
));
8201 * charge this task's execution time to its accounting group.
8203 * called with rq->lock held.
8205 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
)
8209 if (!cpuacct_subsys
.active
)
8214 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, task_cpu(tsk
));
8216 *cpuusage
+= cputime
;
8220 struct cgroup_subsys cpuacct_subsys
= {
8222 .create
= cpuacct_create
,
8223 .destroy
= cpuacct_destroy
,
8224 .populate
= cpuacct_populate
,
8225 .subsys_id
= cpuacct_subsys_id
,
8227 #endif /* CONFIG_CGROUP_CPUACCT */