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_HRTICK
= 8,
629 SCHED_FEAT_DOUBLE_TICK
= 16,
630 SCHED_FEAT_SYNC_WAKEUPS
= 32,
633 const_debug
unsigned int sysctl_sched_features
=
634 SCHED_FEAT_NEW_FAIR_SLEEPERS
* 1 |
635 SCHED_FEAT_WAKEUP_PREEMPT
* 1 |
636 SCHED_FEAT_START_DEBIT
* 1 |
637 SCHED_FEAT_HRTICK
* 1 |
638 SCHED_FEAT_DOUBLE_TICK
* 0 |
639 SCHED_FEAT_SYNC_WAKEUPS
* 0;
641 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
644 * Number of tasks to iterate in a single balance run.
645 * Limited because this is done with IRQs disabled.
647 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
650 * period over which we measure -rt task cpu usage in us.
653 unsigned int sysctl_sched_rt_period
= 1000000;
655 static __read_mostly
int scheduler_running
;
658 * part of the period that we allow rt tasks to run in us.
661 int sysctl_sched_rt_runtime
= 950000;
664 * single value that denotes runtime == period, ie unlimited time.
666 #define RUNTIME_INF ((u64)~0ULL)
668 static const unsigned long long time_sync_thresh
= 100000;
670 static DEFINE_PER_CPU(unsigned long long, time_offset
);
671 static DEFINE_PER_CPU(unsigned long long, prev_cpu_time
);
674 * Global lock which we take every now and then to synchronize
675 * the CPUs time. This method is not warp-safe, but it's good
676 * enough to synchronize slowly diverging time sources and thus
677 * it's good enough for tracing:
679 static DEFINE_SPINLOCK(time_sync_lock
);
680 static unsigned long long prev_global_time
;
682 static unsigned long long __sync_cpu_clock(cycles_t time
, int cpu
)
686 spin_lock_irqsave(&time_sync_lock
, flags
);
688 if (time
< prev_global_time
) {
689 per_cpu(time_offset
, cpu
) += prev_global_time
- time
;
690 time
= prev_global_time
;
692 prev_global_time
= time
;
695 spin_unlock_irqrestore(&time_sync_lock
, flags
);
700 static unsigned long long __cpu_clock(int cpu
)
702 unsigned long long now
;
707 * Only call sched_clock() if the scheduler has already been
708 * initialized (some code might call cpu_clock() very early):
710 if (unlikely(!scheduler_running
))
713 local_irq_save(flags
);
717 local_irq_restore(flags
);
723 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
724 * clock constructed from sched_clock():
726 unsigned long long cpu_clock(int cpu
)
728 unsigned long long prev_cpu_time
, time
, delta_time
;
730 prev_cpu_time
= per_cpu(prev_cpu_time
, cpu
);
731 time
= __cpu_clock(cpu
) + per_cpu(time_offset
, cpu
);
732 delta_time
= time
-prev_cpu_time
;
734 if (unlikely(delta_time
> time_sync_thresh
))
735 time
= __sync_cpu_clock(time
, cpu
);
739 EXPORT_SYMBOL_GPL(cpu_clock
);
741 #ifndef prepare_arch_switch
742 # define prepare_arch_switch(next) do { } while (0)
744 #ifndef finish_arch_switch
745 # define finish_arch_switch(prev) do { } while (0)
748 static inline int task_current(struct rq
*rq
, struct task_struct
*p
)
750 return rq
->curr
== p
;
753 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
754 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
756 return task_current(rq
, p
);
759 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
763 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
765 #ifdef CONFIG_DEBUG_SPINLOCK
766 /* this is a valid case when another task releases the spinlock */
767 rq
->lock
.owner
= current
;
770 * If we are tracking spinlock dependencies then we have to
771 * fix up the runqueue lock - which gets 'carried over' from
774 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
776 spin_unlock_irq(&rq
->lock
);
779 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
780 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
785 return task_current(rq
, p
);
789 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
793 * We can optimise this out completely for !SMP, because the
794 * SMP rebalancing from interrupt is the only thing that cares
799 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
800 spin_unlock_irq(&rq
->lock
);
802 spin_unlock(&rq
->lock
);
806 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
810 * After ->oncpu is cleared, the task can be moved to a different CPU.
811 * We must ensure this doesn't happen until the switch is completely
817 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
821 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
824 * __task_rq_lock - lock the runqueue a given task resides on.
825 * Must be called interrupts disabled.
827 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
831 struct rq
*rq
= task_rq(p
);
832 spin_lock(&rq
->lock
);
833 if (likely(rq
== task_rq(p
)))
835 spin_unlock(&rq
->lock
);
840 * task_rq_lock - lock the runqueue a given task resides on and disable
841 * interrupts. Note the ordering: we can safely lookup the task_rq without
842 * explicitly disabling preemption.
844 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
850 local_irq_save(*flags
);
852 spin_lock(&rq
->lock
);
853 if (likely(rq
== task_rq(p
)))
855 spin_unlock_irqrestore(&rq
->lock
, *flags
);
859 static void __task_rq_unlock(struct rq
*rq
)
862 spin_unlock(&rq
->lock
);
865 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
868 spin_unlock_irqrestore(&rq
->lock
, *flags
);
872 * this_rq_lock - lock this runqueue and disable interrupts.
874 static struct rq
*this_rq_lock(void)
881 spin_lock(&rq
->lock
);
887 * We are going deep-idle (irqs are disabled):
889 void sched_clock_idle_sleep_event(void)
891 struct rq
*rq
= cpu_rq(smp_processor_id());
893 spin_lock(&rq
->lock
);
894 __update_rq_clock(rq
);
895 spin_unlock(&rq
->lock
);
896 rq
->clock_deep_idle_events
++;
898 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
901 * We just idled delta nanoseconds (called with irqs disabled):
903 void sched_clock_idle_wakeup_event(u64 delta_ns
)
905 struct rq
*rq
= cpu_rq(smp_processor_id());
906 u64 now
= sched_clock();
908 rq
->idle_clock
+= delta_ns
;
910 * Override the previous timestamp and ignore all
911 * sched_clock() deltas that occured while we idled,
912 * and use the PM-provided delta_ns to advance the
915 spin_lock(&rq
->lock
);
916 rq
->prev_clock_raw
= now
;
917 rq
->clock
+= delta_ns
;
918 spin_unlock(&rq
->lock
);
919 touch_softlockup_watchdog();
921 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
923 static void __resched_task(struct task_struct
*p
, int tif_bit
);
925 static inline void resched_task(struct task_struct
*p
)
927 __resched_task(p
, TIF_NEED_RESCHED
);
930 #ifdef CONFIG_SCHED_HRTICK
932 * Use HR-timers to deliver accurate preemption points.
934 * Its all a bit involved since we cannot program an hrt while holding the
935 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
938 * When we get rescheduled we reprogram the hrtick_timer outside of the
941 static inline void resched_hrt(struct task_struct
*p
)
943 __resched_task(p
, TIF_HRTICK_RESCHED
);
946 static inline void resched_rq(struct rq
*rq
)
950 spin_lock_irqsave(&rq
->lock
, flags
);
951 resched_task(rq
->curr
);
952 spin_unlock_irqrestore(&rq
->lock
, flags
);
956 HRTICK_SET
, /* re-programm hrtick_timer */
957 HRTICK_RESET
, /* not a new slice */
962 * - enabled by features
963 * - hrtimer is actually high res
965 static inline int hrtick_enabled(struct rq
*rq
)
967 if (!sched_feat(HRTICK
))
969 return hrtimer_is_hres_active(&rq
->hrtick_timer
);
973 * Called to set the hrtick timer state.
975 * called with rq->lock held and irqs disabled
977 static void hrtick_start(struct rq
*rq
, u64 delay
, int reset
)
979 assert_spin_locked(&rq
->lock
);
982 * preempt at: now + delay
985 ktime_add_ns(rq
->hrtick_timer
.base
->get_time(), delay
);
987 * indicate we need to program the timer
989 __set_bit(HRTICK_SET
, &rq
->hrtick_flags
);
991 __set_bit(HRTICK_RESET
, &rq
->hrtick_flags
);
994 * New slices are called from the schedule path and don't need a
998 resched_hrt(rq
->curr
);
1001 static void hrtick_clear(struct rq
*rq
)
1003 if (hrtimer_active(&rq
->hrtick_timer
))
1004 hrtimer_cancel(&rq
->hrtick_timer
);
1008 * Update the timer from the possible pending state.
1010 static void hrtick_set(struct rq
*rq
)
1014 unsigned long flags
;
1016 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
1018 spin_lock_irqsave(&rq
->lock
, flags
);
1019 set
= __test_and_clear_bit(HRTICK_SET
, &rq
->hrtick_flags
);
1020 reset
= __test_and_clear_bit(HRTICK_RESET
, &rq
->hrtick_flags
);
1021 time
= rq
->hrtick_expire
;
1022 clear_thread_flag(TIF_HRTICK_RESCHED
);
1023 spin_unlock_irqrestore(&rq
->lock
, flags
);
1026 hrtimer_start(&rq
->hrtick_timer
, time
, HRTIMER_MODE_ABS
);
1027 if (reset
&& !hrtimer_active(&rq
->hrtick_timer
))
1034 * High-resolution timer tick.
1035 * Runs from hardirq context with interrupts disabled.
1037 static enum hrtimer_restart
hrtick(struct hrtimer
*timer
)
1039 struct rq
*rq
= container_of(timer
, struct rq
, hrtick_timer
);
1041 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
1043 spin_lock(&rq
->lock
);
1044 __update_rq_clock(rq
);
1045 rq
->curr
->sched_class
->task_tick(rq
, rq
->curr
, 1);
1046 spin_unlock(&rq
->lock
);
1048 return HRTIMER_NORESTART
;
1051 static inline void init_rq_hrtick(struct rq
*rq
)
1053 rq
->hrtick_flags
= 0;
1054 hrtimer_init(&rq
->hrtick_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1055 rq
->hrtick_timer
.function
= hrtick
;
1056 rq
->hrtick_timer
.cb_mode
= HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
;
1059 void hrtick_resched(void)
1062 unsigned long flags
;
1064 if (!test_thread_flag(TIF_HRTICK_RESCHED
))
1067 local_irq_save(flags
);
1068 rq
= cpu_rq(smp_processor_id());
1070 local_irq_restore(flags
);
1073 static inline void hrtick_clear(struct rq
*rq
)
1077 static inline void hrtick_set(struct rq
*rq
)
1081 static inline void init_rq_hrtick(struct rq
*rq
)
1085 void hrtick_resched(void)
1091 * resched_task - mark a task 'to be rescheduled now'.
1093 * On UP this means the setting of the need_resched flag, on SMP it
1094 * might also involve a cross-CPU call to trigger the scheduler on
1099 #ifndef tsk_is_polling
1100 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1103 static void __resched_task(struct task_struct
*p
, int tif_bit
)
1107 assert_spin_locked(&task_rq(p
)->lock
);
1109 if (unlikely(test_tsk_thread_flag(p
, tif_bit
)))
1112 set_tsk_thread_flag(p
, tif_bit
);
1115 if (cpu
== smp_processor_id())
1118 /* NEED_RESCHED must be visible before we test polling */
1120 if (!tsk_is_polling(p
))
1121 smp_send_reschedule(cpu
);
1124 static void resched_cpu(int cpu
)
1126 struct rq
*rq
= cpu_rq(cpu
);
1127 unsigned long flags
;
1129 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
1131 resched_task(cpu_curr(cpu
));
1132 spin_unlock_irqrestore(&rq
->lock
, flags
);
1137 * When add_timer_on() enqueues a timer into the timer wheel of an
1138 * idle CPU then this timer might expire before the next timer event
1139 * which is scheduled to wake up that CPU. In case of a completely
1140 * idle system the next event might even be infinite time into the
1141 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1142 * leaves the inner idle loop so the newly added timer is taken into
1143 * account when the CPU goes back to idle and evaluates the timer
1144 * wheel for the next timer event.
1146 void wake_up_idle_cpu(int cpu
)
1148 struct rq
*rq
= cpu_rq(cpu
);
1150 if (cpu
== smp_processor_id())
1154 * This is safe, as this function is called with the timer
1155 * wheel base lock of (cpu) held. When the CPU is on the way
1156 * to idle and has not yet set rq->curr to idle then it will
1157 * be serialized on the timer wheel base lock and take the new
1158 * timer into account automatically.
1160 if (rq
->curr
!= rq
->idle
)
1164 * We can set TIF_RESCHED on the idle task of the other CPU
1165 * lockless. The worst case is that the other CPU runs the
1166 * idle task through an additional NOOP schedule()
1168 set_tsk_thread_flag(rq
->idle
, TIF_NEED_RESCHED
);
1170 /* NEED_RESCHED must be visible before we test polling */
1172 if (!tsk_is_polling(rq
->idle
))
1173 smp_send_reschedule(cpu
);
1178 static void __resched_task(struct task_struct
*p
, int tif_bit
)
1180 assert_spin_locked(&task_rq(p
)->lock
);
1181 set_tsk_thread_flag(p
, tif_bit
);
1185 #if BITS_PER_LONG == 32
1186 # define WMULT_CONST (~0UL)
1188 # define WMULT_CONST (1UL << 32)
1191 #define WMULT_SHIFT 32
1194 * Shift right and round:
1196 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1198 static unsigned long
1199 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
1200 struct load_weight
*lw
)
1204 if (unlikely(!lw
->inv_weight
))
1205 lw
->inv_weight
= (WMULT_CONST
-lw
->weight
/2) / (lw
->weight
+1);
1207 tmp
= (u64
)delta_exec
* weight
;
1209 * Check whether we'd overflow the 64-bit multiplication:
1211 if (unlikely(tmp
> WMULT_CONST
))
1212 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
1215 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
1217 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
1220 static inline unsigned long
1221 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
1223 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
1226 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
1232 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
1239 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1240 * of tasks with abnormal "nice" values across CPUs the contribution that
1241 * each task makes to its run queue's load is weighted according to its
1242 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1243 * scaled version of the new time slice allocation that they receive on time
1247 #define WEIGHT_IDLEPRIO 2
1248 #define WMULT_IDLEPRIO (1 << 31)
1251 * Nice levels are multiplicative, with a gentle 10% change for every
1252 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1253 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1254 * that remained on nice 0.
1256 * The "10% effect" is relative and cumulative: from _any_ nice level,
1257 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1258 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1259 * If a task goes up by ~10% and another task goes down by ~10% then
1260 * the relative distance between them is ~25%.)
1262 static const int prio_to_weight
[40] = {
1263 /* -20 */ 88761, 71755, 56483, 46273, 36291,
1264 /* -15 */ 29154, 23254, 18705, 14949, 11916,
1265 /* -10 */ 9548, 7620, 6100, 4904, 3906,
1266 /* -5 */ 3121, 2501, 1991, 1586, 1277,
1267 /* 0 */ 1024, 820, 655, 526, 423,
1268 /* 5 */ 335, 272, 215, 172, 137,
1269 /* 10 */ 110, 87, 70, 56, 45,
1270 /* 15 */ 36, 29, 23, 18, 15,
1274 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1276 * In cases where the weight does not change often, we can use the
1277 * precalculated inverse to speed up arithmetics by turning divisions
1278 * into multiplications:
1280 static const u32 prio_to_wmult
[40] = {
1281 /* -20 */ 48388, 59856, 76040, 92818, 118348,
1282 /* -15 */ 147320, 184698, 229616, 287308, 360437,
1283 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
1284 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1285 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1286 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1287 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1288 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1291 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
1294 * runqueue iterator, to support SMP load-balancing between different
1295 * scheduling classes, without having to expose their internal data
1296 * structures to the load-balancing proper:
1298 struct rq_iterator
{
1300 struct task_struct
*(*start
)(void *);
1301 struct task_struct
*(*next
)(void *);
1305 static unsigned long
1306 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1307 unsigned long max_load_move
, struct sched_domain
*sd
,
1308 enum cpu_idle_type idle
, int *all_pinned
,
1309 int *this_best_prio
, struct rq_iterator
*iterator
);
1312 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
1313 struct sched_domain
*sd
, enum cpu_idle_type idle
,
1314 struct rq_iterator
*iterator
);
1317 #ifdef CONFIG_CGROUP_CPUACCT
1318 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
);
1320 static inline void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
) {}
1324 static unsigned long source_load(int cpu
, int type
);
1325 static unsigned long target_load(int cpu
, int type
);
1326 static unsigned long cpu_avg_load_per_task(int cpu
);
1327 static int task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
);
1328 #endif /* CONFIG_SMP */
1330 #include "sched_stats.h"
1331 #include "sched_idletask.c"
1332 #include "sched_fair.c"
1333 #include "sched_rt.c"
1334 #ifdef CONFIG_SCHED_DEBUG
1335 # include "sched_debug.c"
1338 #define sched_class_highest (&rt_sched_class)
1340 static inline void inc_load(struct rq
*rq
, const struct task_struct
*p
)
1342 update_load_add(&rq
->load
, p
->se
.load
.weight
);
1345 static inline void dec_load(struct rq
*rq
, const struct task_struct
*p
)
1347 update_load_sub(&rq
->load
, p
->se
.load
.weight
);
1350 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
1356 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
1362 static void set_load_weight(struct task_struct
*p
)
1364 if (task_has_rt_policy(p
)) {
1365 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
1366 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
1371 * SCHED_IDLE tasks get minimal weight:
1373 if (p
->policy
== SCHED_IDLE
) {
1374 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
1375 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
1379 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
1380 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
1383 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
1385 sched_info_queued(p
);
1386 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
1390 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1392 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
1397 * __normal_prio - return the priority that is based on the static prio
1399 static inline int __normal_prio(struct task_struct
*p
)
1401 return p
->static_prio
;
1405 * Calculate the expected normal priority: i.e. priority
1406 * without taking RT-inheritance into account. Might be
1407 * boosted by interactivity modifiers. Changes upon fork,
1408 * setprio syscalls, and whenever the interactivity
1409 * estimator recalculates.
1411 static inline int normal_prio(struct task_struct
*p
)
1415 if (task_has_rt_policy(p
))
1416 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
1418 prio
= __normal_prio(p
);
1423 * Calculate the current priority, i.e. the priority
1424 * taken into account by the scheduler. This value might
1425 * be boosted by RT tasks, or might be boosted by
1426 * interactivity modifiers. Will be RT if the task got
1427 * RT-boosted. If not then it returns p->normal_prio.
1429 static int effective_prio(struct task_struct
*p
)
1431 p
->normal_prio
= normal_prio(p
);
1433 * If we are RT tasks or we were boosted to RT priority,
1434 * keep the priority unchanged. Otherwise, update priority
1435 * to the normal priority:
1437 if (!rt_prio(p
->prio
))
1438 return p
->normal_prio
;
1443 * activate_task - move a task to the runqueue.
1445 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
1447 if (task_contributes_to_load(p
))
1448 rq
->nr_uninterruptible
--;
1450 enqueue_task(rq
, p
, wakeup
);
1451 inc_nr_running(p
, rq
);
1455 * deactivate_task - remove a task from the runqueue.
1457 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1459 if (task_contributes_to_load(p
))
1460 rq
->nr_uninterruptible
++;
1462 dequeue_task(rq
, p
, sleep
);
1463 dec_nr_running(p
, rq
);
1467 * task_curr - is this task currently executing on a CPU?
1468 * @p: the task in question.
1470 inline int task_curr(const struct task_struct
*p
)
1472 return cpu_curr(task_cpu(p
)) == p
;
1475 /* Used instead of source_load when we know the type == 0 */
1476 unsigned long weighted_cpuload(const int cpu
)
1478 return cpu_rq(cpu
)->load
.weight
;
1481 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
1483 set_task_rq(p
, cpu
);
1486 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1487 * successfuly executed on another CPU. We must ensure that updates of
1488 * per-task data have been completed by this moment.
1491 task_thread_info(p
)->cpu
= cpu
;
1495 static inline void check_class_changed(struct rq
*rq
, struct task_struct
*p
,
1496 const struct sched_class
*prev_class
,
1497 int oldprio
, int running
)
1499 if (prev_class
!= p
->sched_class
) {
1500 if (prev_class
->switched_from
)
1501 prev_class
->switched_from(rq
, p
, running
);
1502 p
->sched_class
->switched_to(rq
, p
, running
);
1504 p
->sched_class
->prio_changed(rq
, p
, oldprio
, running
);
1510 * Is this task likely cache-hot:
1513 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
1518 * Buddy candidates are cache hot:
1520 if (&p
->se
== cfs_rq_of(&p
->se
)->next
)
1523 if (p
->sched_class
!= &fair_sched_class
)
1526 if (sysctl_sched_migration_cost
== -1)
1528 if (sysctl_sched_migration_cost
== 0)
1531 delta
= now
- p
->se
.exec_start
;
1533 return delta
< (s64
)sysctl_sched_migration_cost
;
1537 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1539 int old_cpu
= task_cpu(p
);
1540 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
1541 struct cfs_rq
*old_cfsrq
= task_cfs_rq(p
),
1542 *new_cfsrq
= cpu_cfs_rq(old_cfsrq
, new_cpu
);
1545 clock_offset
= old_rq
->clock
- new_rq
->clock
;
1547 #ifdef CONFIG_SCHEDSTATS
1548 if (p
->se
.wait_start
)
1549 p
->se
.wait_start
-= clock_offset
;
1550 if (p
->se
.sleep_start
)
1551 p
->se
.sleep_start
-= clock_offset
;
1552 if (p
->se
.block_start
)
1553 p
->se
.block_start
-= clock_offset
;
1554 if (old_cpu
!= new_cpu
) {
1555 schedstat_inc(p
, se
.nr_migrations
);
1556 if (task_hot(p
, old_rq
->clock
, NULL
))
1557 schedstat_inc(p
, se
.nr_forced2_migrations
);
1560 p
->se
.vruntime
-= old_cfsrq
->min_vruntime
-
1561 new_cfsrq
->min_vruntime
;
1563 __set_task_cpu(p
, new_cpu
);
1566 struct migration_req
{
1567 struct list_head list
;
1569 struct task_struct
*task
;
1572 struct completion done
;
1576 * The task's runqueue lock must be held.
1577 * Returns true if you have to wait for migration thread.
1580 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1582 struct rq
*rq
= task_rq(p
);
1585 * If the task is not on a runqueue (and not running), then
1586 * it is sufficient to simply update the task's cpu field.
1588 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1589 set_task_cpu(p
, dest_cpu
);
1593 init_completion(&req
->done
);
1595 req
->dest_cpu
= dest_cpu
;
1596 list_add(&req
->list
, &rq
->migration_queue
);
1602 * wait_task_inactive - wait for a thread to unschedule.
1604 * The caller must ensure that the task *will* unschedule sometime soon,
1605 * else this function might spin for a *long* time. This function can't
1606 * be called with interrupts off, or it may introduce deadlock with
1607 * smp_call_function() if an IPI is sent by the same process we are
1608 * waiting to become inactive.
1610 void wait_task_inactive(struct task_struct
*p
)
1612 unsigned long flags
;
1618 * We do the initial early heuristics without holding
1619 * any task-queue locks at all. We'll only try to get
1620 * the runqueue lock when things look like they will
1626 * If the task is actively running on another CPU
1627 * still, just relax and busy-wait without holding
1630 * NOTE! Since we don't hold any locks, it's not
1631 * even sure that "rq" stays as the right runqueue!
1632 * But we don't care, since "task_running()" will
1633 * return false if the runqueue has changed and p
1634 * is actually now running somewhere else!
1636 while (task_running(rq
, p
))
1640 * Ok, time to look more closely! We need the rq
1641 * lock now, to be *sure*. If we're wrong, we'll
1642 * just go back and repeat.
1644 rq
= task_rq_lock(p
, &flags
);
1645 running
= task_running(rq
, p
);
1646 on_rq
= p
->se
.on_rq
;
1647 task_rq_unlock(rq
, &flags
);
1650 * Was it really running after all now that we
1651 * checked with the proper locks actually held?
1653 * Oops. Go back and try again..
1655 if (unlikely(running
)) {
1661 * It's not enough that it's not actively running,
1662 * it must be off the runqueue _entirely_, and not
1665 * So if it wa still runnable (but just not actively
1666 * running right now), it's preempted, and we should
1667 * yield - it could be a while.
1669 if (unlikely(on_rq
)) {
1670 schedule_timeout_uninterruptible(1);
1675 * Ahh, all good. It wasn't running, and it wasn't
1676 * runnable, which means that it will never become
1677 * running in the future either. We're all done!
1684 * kick_process - kick a running thread to enter/exit the kernel
1685 * @p: the to-be-kicked thread
1687 * Cause a process which is running on another CPU to enter
1688 * kernel-mode, without any delay. (to get signals handled.)
1690 * NOTE: this function doesnt have to take the runqueue lock,
1691 * because all it wants to ensure is that the remote task enters
1692 * the kernel. If the IPI races and the task has been migrated
1693 * to another CPU then no harm is done and the purpose has been
1696 void kick_process(struct task_struct
*p
)
1702 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1703 smp_send_reschedule(cpu
);
1708 * Return a low guess at the load of a migration-source cpu weighted
1709 * according to the scheduling class and "nice" value.
1711 * We want to under-estimate the load of migration sources, to
1712 * balance conservatively.
1714 static unsigned long source_load(int cpu
, int type
)
1716 struct rq
*rq
= cpu_rq(cpu
);
1717 unsigned long total
= weighted_cpuload(cpu
);
1722 return min(rq
->cpu_load
[type
-1], total
);
1726 * Return a high guess at the load of a migration-target cpu weighted
1727 * according to the scheduling class and "nice" value.
1729 static unsigned long target_load(int cpu
, int type
)
1731 struct rq
*rq
= cpu_rq(cpu
);
1732 unsigned long total
= weighted_cpuload(cpu
);
1737 return max(rq
->cpu_load
[type
-1], total
);
1741 * Return the average load per task on the cpu's run queue
1743 static unsigned long cpu_avg_load_per_task(int cpu
)
1745 struct rq
*rq
= cpu_rq(cpu
);
1746 unsigned long total
= weighted_cpuload(cpu
);
1747 unsigned long n
= rq
->nr_running
;
1749 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1753 * find_idlest_group finds and returns the least busy CPU group within the
1756 static struct sched_group
*
1757 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1759 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1760 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1761 int load_idx
= sd
->forkexec_idx
;
1762 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1765 unsigned long load
, avg_load
;
1769 /* Skip over this group if it has no CPUs allowed */
1770 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1773 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1775 /* Tally up the load of all CPUs in the group */
1778 for_each_cpu_mask(i
, group
->cpumask
) {
1779 /* Bias balancing toward cpus of our domain */
1781 load
= source_load(i
, load_idx
);
1783 load
= target_load(i
, load_idx
);
1788 /* Adjust by relative CPU power of the group */
1789 avg_load
= sg_div_cpu_power(group
,
1790 avg_load
* SCHED_LOAD_SCALE
);
1793 this_load
= avg_load
;
1795 } else if (avg_load
< min_load
) {
1796 min_load
= avg_load
;
1799 } while (group
= group
->next
, group
!= sd
->groups
);
1801 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1807 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1810 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1813 unsigned long load
, min_load
= ULONG_MAX
;
1817 /* Traverse only the allowed CPUs */
1818 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1820 for_each_cpu_mask(i
, tmp
) {
1821 load
= weighted_cpuload(i
);
1823 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1833 * sched_balance_self: balance the current task (running on cpu) in domains
1834 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1837 * Balance, ie. select the least loaded group.
1839 * Returns the target CPU number, or the same CPU if no balancing is needed.
1841 * preempt must be disabled.
1843 static int sched_balance_self(int cpu
, int flag
)
1845 struct task_struct
*t
= current
;
1846 struct sched_domain
*tmp
, *sd
= NULL
;
1848 for_each_domain(cpu
, tmp
) {
1850 * If power savings logic is enabled for a domain, stop there.
1852 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1854 if (tmp
->flags
& flag
)
1860 struct sched_group
*group
;
1861 int new_cpu
, weight
;
1863 if (!(sd
->flags
& flag
)) {
1869 group
= find_idlest_group(sd
, t
, cpu
);
1875 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1876 if (new_cpu
== -1 || new_cpu
== cpu
) {
1877 /* Now try balancing at a lower domain level of cpu */
1882 /* Now try balancing at a lower domain level of new_cpu */
1885 weight
= cpus_weight(span
);
1886 for_each_domain(cpu
, tmp
) {
1887 if (weight
<= cpus_weight(tmp
->span
))
1889 if (tmp
->flags
& flag
)
1892 /* while loop will break here if sd == NULL */
1898 #endif /* CONFIG_SMP */
1901 * try_to_wake_up - wake up a thread
1902 * @p: the to-be-woken-up thread
1903 * @state: the mask of task states that can be woken
1904 * @sync: do a synchronous wakeup?
1906 * Put it on the run-queue if it's not already there. The "current"
1907 * thread is always on the run-queue (except when the actual
1908 * re-schedule is in progress), and as such you're allowed to do
1909 * the simpler "current->state = TASK_RUNNING" to mark yourself
1910 * runnable without the overhead of this.
1912 * returns failure only if the task is already active.
1914 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1916 int cpu
, orig_cpu
, this_cpu
, success
= 0;
1917 unsigned long flags
;
1921 if (!sched_feat(SYNC_WAKEUPS
))
1925 rq
= task_rq_lock(p
, &flags
);
1926 old_state
= p
->state
;
1927 if (!(old_state
& state
))
1935 this_cpu
= smp_processor_id();
1938 if (unlikely(task_running(rq
, p
)))
1941 cpu
= p
->sched_class
->select_task_rq(p
, sync
);
1942 if (cpu
!= orig_cpu
) {
1943 set_task_cpu(p
, cpu
);
1944 task_rq_unlock(rq
, &flags
);
1945 /* might preempt at this point */
1946 rq
= task_rq_lock(p
, &flags
);
1947 old_state
= p
->state
;
1948 if (!(old_state
& state
))
1953 this_cpu
= smp_processor_id();
1957 #ifdef CONFIG_SCHEDSTATS
1958 schedstat_inc(rq
, ttwu_count
);
1959 if (cpu
== this_cpu
)
1960 schedstat_inc(rq
, ttwu_local
);
1962 struct sched_domain
*sd
;
1963 for_each_domain(this_cpu
, sd
) {
1964 if (cpu_isset(cpu
, sd
->span
)) {
1965 schedstat_inc(sd
, ttwu_wake_remote
);
1973 #endif /* CONFIG_SMP */
1974 schedstat_inc(p
, se
.nr_wakeups
);
1976 schedstat_inc(p
, se
.nr_wakeups_sync
);
1977 if (orig_cpu
!= cpu
)
1978 schedstat_inc(p
, se
.nr_wakeups_migrate
);
1979 if (cpu
== this_cpu
)
1980 schedstat_inc(p
, se
.nr_wakeups_local
);
1982 schedstat_inc(p
, se
.nr_wakeups_remote
);
1983 update_rq_clock(rq
);
1984 activate_task(rq
, p
, 1);
1988 check_preempt_curr(rq
, p
);
1990 p
->state
= TASK_RUNNING
;
1992 if (p
->sched_class
->task_wake_up
)
1993 p
->sched_class
->task_wake_up(rq
, p
);
1996 task_rq_unlock(rq
, &flags
);
2001 int wake_up_process(struct task_struct
*p
)
2003 return try_to_wake_up(p
, TASK_ALL
, 0);
2005 EXPORT_SYMBOL(wake_up_process
);
2007 int wake_up_state(struct task_struct
*p
, unsigned int state
)
2009 return try_to_wake_up(p
, state
, 0);
2013 * Perform scheduler related setup for a newly forked process p.
2014 * p is forked by current.
2016 * __sched_fork() is basic setup used by init_idle() too:
2018 static void __sched_fork(struct task_struct
*p
)
2020 p
->se
.exec_start
= 0;
2021 p
->se
.sum_exec_runtime
= 0;
2022 p
->se
.prev_sum_exec_runtime
= 0;
2023 p
->se
.last_wakeup
= 0;
2024 p
->se
.avg_overlap
= 0;
2026 #ifdef CONFIG_SCHEDSTATS
2027 p
->se
.wait_start
= 0;
2028 p
->se
.sum_sleep_runtime
= 0;
2029 p
->se
.sleep_start
= 0;
2030 p
->se
.block_start
= 0;
2031 p
->se
.sleep_max
= 0;
2032 p
->se
.block_max
= 0;
2034 p
->se
.slice_max
= 0;
2038 INIT_LIST_HEAD(&p
->rt
.run_list
);
2041 #ifdef CONFIG_PREEMPT_NOTIFIERS
2042 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
2046 * We mark the process as running here, but have not actually
2047 * inserted it onto the runqueue yet. This guarantees that
2048 * nobody will actually run it, and a signal or other external
2049 * event cannot wake it up and insert it on the runqueue either.
2051 p
->state
= TASK_RUNNING
;
2055 * fork()/clone()-time setup:
2057 void sched_fork(struct task_struct
*p
, int clone_flags
)
2059 int cpu
= get_cpu();
2064 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
2066 set_task_cpu(p
, cpu
);
2069 * Make sure we do not leak PI boosting priority to the child:
2071 p
->prio
= current
->normal_prio
;
2072 if (!rt_prio(p
->prio
))
2073 p
->sched_class
= &fair_sched_class
;
2075 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2076 if (likely(sched_info_on()))
2077 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
2079 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
2082 #ifdef CONFIG_PREEMPT
2083 /* Want to start with kernel preemption disabled. */
2084 task_thread_info(p
)->preempt_count
= 1;
2090 * wake_up_new_task - wake up a newly created task for the first time.
2092 * This function will do some initial scheduler statistics housekeeping
2093 * that must be done for every newly created context, then puts the task
2094 * on the runqueue and wakes it.
2096 void wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
2098 unsigned long flags
;
2101 rq
= task_rq_lock(p
, &flags
);
2102 BUG_ON(p
->state
!= TASK_RUNNING
);
2103 update_rq_clock(rq
);
2105 p
->prio
= effective_prio(p
);
2107 if (!p
->sched_class
->task_new
|| !current
->se
.on_rq
) {
2108 activate_task(rq
, p
, 0);
2111 * Let the scheduling class do new task startup
2112 * management (if any):
2114 p
->sched_class
->task_new(rq
, p
);
2115 inc_nr_running(p
, rq
);
2117 check_preempt_curr(rq
, p
);
2119 if (p
->sched_class
->task_wake_up
)
2120 p
->sched_class
->task_wake_up(rq
, p
);
2122 task_rq_unlock(rq
, &flags
);
2125 #ifdef CONFIG_PREEMPT_NOTIFIERS
2128 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
2129 * @notifier: notifier struct to register
2131 void preempt_notifier_register(struct preempt_notifier
*notifier
)
2133 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
2135 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
2138 * preempt_notifier_unregister - no longer interested in preemption notifications
2139 * @notifier: notifier struct to unregister
2141 * This is safe to call from within a preemption notifier.
2143 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
2145 hlist_del(¬ifier
->link
);
2147 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
2149 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2151 struct preempt_notifier
*notifier
;
2152 struct hlist_node
*node
;
2154 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2155 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
2159 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2160 struct task_struct
*next
)
2162 struct preempt_notifier
*notifier
;
2163 struct hlist_node
*node
;
2165 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
2166 notifier
->ops
->sched_out(notifier
, next
);
2171 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
2176 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
2177 struct task_struct
*next
)
2184 * prepare_task_switch - prepare to switch tasks
2185 * @rq: the runqueue preparing to switch
2186 * @prev: the current task that is being switched out
2187 * @next: the task we are going to switch to.
2189 * This is called with the rq lock held and interrupts off. It must
2190 * be paired with a subsequent finish_task_switch after the context
2193 * prepare_task_switch sets up locking and calls architecture specific
2197 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
2198 struct task_struct
*next
)
2200 fire_sched_out_preempt_notifiers(prev
, next
);
2201 prepare_lock_switch(rq
, next
);
2202 prepare_arch_switch(next
);
2206 * finish_task_switch - clean up after a task-switch
2207 * @rq: runqueue associated with task-switch
2208 * @prev: the thread we just switched away from.
2210 * finish_task_switch must be called after the context switch, paired
2211 * with a prepare_task_switch call before the context switch.
2212 * finish_task_switch will reconcile locking set up by prepare_task_switch,
2213 * and do any other architecture-specific cleanup actions.
2215 * Note that we may have delayed dropping an mm in context_switch(). If
2216 * so, we finish that here outside of the runqueue lock. (Doing it
2217 * with the lock held can cause deadlocks; see schedule() for
2220 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
2221 __releases(rq
->lock
)
2223 struct mm_struct
*mm
= rq
->prev_mm
;
2229 * A task struct has one reference for the use as "current".
2230 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
2231 * schedule one last time. The schedule call will never return, and
2232 * the scheduled task must drop that reference.
2233 * The test for TASK_DEAD must occur while the runqueue locks are
2234 * still held, otherwise prev could be scheduled on another cpu, die
2235 * there before we look at prev->state, and then the reference would
2237 * Manfred Spraul <manfred@colorfullife.com>
2239 prev_state
= prev
->state
;
2240 finish_arch_switch(prev
);
2241 finish_lock_switch(rq
, prev
);
2243 if (current
->sched_class
->post_schedule
)
2244 current
->sched_class
->post_schedule(rq
);
2247 fire_sched_in_preempt_notifiers(current
);
2250 if (unlikely(prev_state
== TASK_DEAD
)) {
2252 * Remove function-return probe instances associated with this
2253 * task and put them back on the free list.
2255 kprobe_flush_task(prev
);
2256 put_task_struct(prev
);
2261 * schedule_tail - first thing a freshly forked thread must call.
2262 * @prev: the thread we just switched away from.
2264 asmlinkage
void schedule_tail(struct task_struct
*prev
)
2265 __releases(rq
->lock
)
2267 struct rq
*rq
= this_rq();
2269 finish_task_switch(rq
, prev
);
2270 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
2271 /* In this case, finish_task_switch does not reenable preemption */
2274 if (current
->set_child_tid
)
2275 put_user(task_pid_vnr(current
), current
->set_child_tid
);
2279 * context_switch - switch to the new MM and the new
2280 * thread's register state.
2283 context_switch(struct rq
*rq
, struct task_struct
*prev
,
2284 struct task_struct
*next
)
2286 struct mm_struct
*mm
, *oldmm
;
2288 prepare_task_switch(rq
, prev
, next
);
2290 oldmm
= prev
->active_mm
;
2292 * For paravirt, this is coupled with an exit in switch_to to
2293 * combine the page table reload and the switch backend into
2296 arch_enter_lazy_cpu_mode();
2298 if (unlikely(!mm
)) {
2299 next
->active_mm
= oldmm
;
2300 atomic_inc(&oldmm
->mm_count
);
2301 enter_lazy_tlb(oldmm
, next
);
2303 switch_mm(oldmm
, mm
, next
);
2305 if (unlikely(!prev
->mm
)) {
2306 prev
->active_mm
= NULL
;
2307 rq
->prev_mm
= oldmm
;
2310 * Since the runqueue lock will be released by the next
2311 * task (which is an invalid locking op but in the case
2312 * of the scheduler it's an obvious special-case), so we
2313 * do an early lockdep release here:
2315 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
2316 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
2319 /* Here we just switch the register state and the stack. */
2320 switch_to(prev
, next
, prev
);
2324 * this_rq must be evaluated again because prev may have moved
2325 * CPUs since it called schedule(), thus the 'rq' on its stack
2326 * frame will be invalid.
2328 finish_task_switch(this_rq(), prev
);
2332 * nr_running, nr_uninterruptible and nr_context_switches:
2334 * externally visible scheduler statistics: current number of runnable
2335 * threads, current number of uninterruptible-sleeping threads, total
2336 * number of context switches performed since bootup.
2338 unsigned long nr_running(void)
2340 unsigned long i
, sum
= 0;
2342 for_each_online_cpu(i
)
2343 sum
+= cpu_rq(i
)->nr_running
;
2348 unsigned long nr_uninterruptible(void)
2350 unsigned long i
, sum
= 0;
2352 for_each_possible_cpu(i
)
2353 sum
+= cpu_rq(i
)->nr_uninterruptible
;
2356 * Since we read the counters lockless, it might be slightly
2357 * inaccurate. Do not allow it to go below zero though:
2359 if (unlikely((long)sum
< 0))
2365 unsigned long long nr_context_switches(void)
2368 unsigned long long sum
= 0;
2370 for_each_possible_cpu(i
)
2371 sum
+= cpu_rq(i
)->nr_switches
;
2376 unsigned long nr_iowait(void)
2378 unsigned long i
, sum
= 0;
2380 for_each_possible_cpu(i
)
2381 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2386 unsigned long nr_active(void)
2388 unsigned long i
, running
= 0, uninterruptible
= 0;
2390 for_each_online_cpu(i
) {
2391 running
+= cpu_rq(i
)->nr_running
;
2392 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
2395 if (unlikely((long)uninterruptible
< 0))
2396 uninterruptible
= 0;
2398 return running
+ uninterruptible
;
2402 * Update rq->cpu_load[] statistics. This function is usually called every
2403 * scheduler tick (TICK_NSEC).
2405 static void update_cpu_load(struct rq
*this_rq
)
2407 unsigned long this_load
= this_rq
->load
.weight
;
2410 this_rq
->nr_load_updates
++;
2412 /* Update our load: */
2413 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2414 unsigned long old_load
, new_load
;
2416 /* scale is effectively 1 << i now, and >> i divides by scale */
2418 old_load
= this_rq
->cpu_load
[i
];
2419 new_load
= this_load
;
2421 * Round up the averaging division if load is increasing. This
2422 * prevents us from getting stuck on 9 if the load is 10, for
2425 if (new_load
> old_load
)
2426 new_load
+= scale
-1;
2427 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2434 * double_rq_lock - safely lock two runqueues
2436 * Note this does not disable interrupts like task_rq_lock,
2437 * you need to do so manually before calling.
2439 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
2440 __acquires(rq1
->lock
)
2441 __acquires(rq2
->lock
)
2443 BUG_ON(!irqs_disabled());
2445 spin_lock(&rq1
->lock
);
2446 __acquire(rq2
->lock
); /* Fake it out ;) */
2449 spin_lock(&rq1
->lock
);
2450 spin_lock(&rq2
->lock
);
2452 spin_lock(&rq2
->lock
);
2453 spin_lock(&rq1
->lock
);
2456 update_rq_clock(rq1
);
2457 update_rq_clock(rq2
);
2461 * double_rq_unlock - safely unlock two runqueues
2463 * Note this does not restore interrupts like task_rq_unlock,
2464 * you need to do so manually after calling.
2466 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2467 __releases(rq1
->lock
)
2468 __releases(rq2
->lock
)
2470 spin_unlock(&rq1
->lock
);
2472 spin_unlock(&rq2
->lock
);
2474 __release(rq2
->lock
);
2478 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2480 static int double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2481 __releases(this_rq
->lock
)
2482 __acquires(busiest
->lock
)
2483 __acquires(this_rq
->lock
)
2487 if (unlikely(!irqs_disabled())) {
2488 /* printk() doesn't work good under rq->lock */
2489 spin_unlock(&this_rq
->lock
);
2492 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2493 if (busiest
< this_rq
) {
2494 spin_unlock(&this_rq
->lock
);
2495 spin_lock(&busiest
->lock
);
2496 spin_lock(&this_rq
->lock
);
2499 spin_lock(&busiest
->lock
);
2505 * If dest_cpu is allowed for this process, migrate the task to it.
2506 * This is accomplished by forcing the cpu_allowed mask to only
2507 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2508 * the cpu_allowed mask is restored.
2510 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2512 struct migration_req req
;
2513 unsigned long flags
;
2516 rq
= task_rq_lock(p
, &flags
);
2517 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2518 || unlikely(cpu_is_offline(dest_cpu
)))
2521 /* force the process onto the specified CPU */
2522 if (migrate_task(p
, dest_cpu
, &req
)) {
2523 /* Need to wait for migration thread (might exit: take ref). */
2524 struct task_struct
*mt
= rq
->migration_thread
;
2526 get_task_struct(mt
);
2527 task_rq_unlock(rq
, &flags
);
2528 wake_up_process(mt
);
2529 put_task_struct(mt
);
2530 wait_for_completion(&req
.done
);
2535 task_rq_unlock(rq
, &flags
);
2539 * sched_exec - execve() is a valuable balancing opportunity, because at
2540 * this point the task has the smallest effective memory and cache footprint.
2542 void sched_exec(void)
2544 int new_cpu
, this_cpu
= get_cpu();
2545 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2547 if (new_cpu
!= this_cpu
)
2548 sched_migrate_task(current
, new_cpu
);
2552 * pull_task - move a task from a remote runqueue to the local runqueue.
2553 * Both runqueues must be locked.
2555 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2556 struct rq
*this_rq
, int this_cpu
)
2558 deactivate_task(src_rq
, p
, 0);
2559 set_task_cpu(p
, this_cpu
);
2560 activate_task(this_rq
, p
, 0);
2562 * Note that idle threads have a prio of MAX_PRIO, for this test
2563 * to be always true for them.
2565 check_preempt_curr(this_rq
, p
);
2569 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2572 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2573 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2577 * We do not migrate tasks that are:
2578 * 1) running (obviously), or
2579 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2580 * 3) are cache-hot on their current CPU.
2582 if (!cpu_isset(this_cpu
, p
->cpus_allowed
)) {
2583 schedstat_inc(p
, se
.nr_failed_migrations_affine
);
2588 if (task_running(rq
, p
)) {
2589 schedstat_inc(p
, se
.nr_failed_migrations_running
);
2594 * Aggressive migration if:
2595 * 1) task is cache cold, or
2596 * 2) too many balance attempts have failed.
2599 if (!task_hot(p
, rq
->clock
, sd
) ||
2600 sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2601 #ifdef CONFIG_SCHEDSTATS
2602 if (task_hot(p
, rq
->clock
, sd
)) {
2603 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2604 schedstat_inc(p
, se
.nr_forced_migrations
);
2610 if (task_hot(p
, rq
->clock
, sd
)) {
2611 schedstat_inc(p
, se
.nr_failed_migrations_hot
);
2617 static unsigned long
2618 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2619 unsigned long max_load_move
, struct sched_domain
*sd
,
2620 enum cpu_idle_type idle
, int *all_pinned
,
2621 int *this_best_prio
, struct rq_iterator
*iterator
)
2623 int loops
= 0, pulled
= 0, pinned
= 0, skip_for_load
;
2624 struct task_struct
*p
;
2625 long rem_load_move
= max_load_move
;
2627 if (max_load_move
== 0)
2633 * Start the load-balancing iterator:
2635 p
= iterator
->start(iterator
->arg
);
2637 if (!p
|| loops
++ > sysctl_sched_nr_migrate
)
2640 * To help distribute high priority tasks across CPUs we don't
2641 * skip a task if it will be the highest priority task (i.e. smallest
2642 * prio value) on its new queue regardless of its load weight
2644 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2645 SCHED_LOAD_SCALE_FUZZ
;
2646 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2647 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2648 p
= iterator
->next(iterator
->arg
);
2652 pull_task(busiest
, p
, this_rq
, this_cpu
);
2654 rem_load_move
-= p
->se
.load
.weight
;
2657 * We only want to steal up to the prescribed amount of weighted load.
2659 if (rem_load_move
> 0) {
2660 if (p
->prio
< *this_best_prio
)
2661 *this_best_prio
= p
->prio
;
2662 p
= iterator
->next(iterator
->arg
);
2667 * Right now, this is one of only two places pull_task() is called,
2668 * so we can safely collect pull_task() stats here rather than
2669 * inside pull_task().
2671 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2674 *all_pinned
= pinned
;
2676 return max_load_move
- rem_load_move
;
2680 * move_tasks tries to move up to max_load_move weighted load from busiest to
2681 * this_rq, as part of a balancing operation within domain "sd".
2682 * Returns 1 if successful and 0 otherwise.
2684 * Called with both runqueues locked.
2686 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2687 unsigned long max_load_move
,
2688 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2691 const struct sched_class
*class = sched_class_highest
;
2692 unsigned long total_load_moved
= 0;
2693 int this_best_prio
= this_rq
->curr
->prio
;
2697 class->load_balance(this_rq
, this_cpu
, busiest
,
2698 max_load_move
- total_load_moved
,
2699 sd
, idle
, all_pinned
, &this_best_prio
);
2700 class = class->next
;
2701 } while (class && max_load_move
> total_load_moved
);
2703 return total_load_moved
> 0;
2707 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2708 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2709 struct rq_iterator
*iterator
)
2711 struct task_struct
*p
= iterator
->start(iterator
->arg
);
2715 if (can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2716 pull_task(busiest
, p
, this_rq
, this_cpu
);
2718 * Right now, this is only the second place pull_task()
2719 * is called, so we can safely collect pull_task()
2720 * stats here rather than inside pull_task().
2722 schedstat_inc(sd
, lb_gained
[idle
]);
2726 p
= iterator
->next(iterator
->arg
);
2733 * move_one_task tries to move exactly one task from busiest to this_rq, as
2734 * part of active balancing operations within "domain".
2735 * Returns 1 if successful and 0 otherwise.
2737 * Called with both runqueues locked.
2739 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2740 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2742 const struct sched_class
*class;
2744 for (class = sched_class_highest
; class; class = class->next
)
2745 if (class->move_one_task(this_rq
, this_cpu
, busiest
, sd
, idle
))
2752 * find_busiest_group finds and returns the busiest CPU group within the
2753 * domain. It calculates and returns the amount of weighted load which
2754 * should be moved to restore balance via the imbalance parameter.
2756 static struct sched_group
*
2757 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2758 unsigned long *imbalance
, enum cpu_idle_type idle
,
2759 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2761 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2762 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2763 unsigned long max_pull
;
2764 unsigned long busiest_load_per_task
, busiest_nr_running
;
2765 unsigned long this_load_per_task
, this_nr_running
;
2766 int load_idx
, group_imb
= 0;
2767 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2768 int power_savings_balance
= 1;
2769 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2770 unsigned long min_nr_running
= ULONG_MAX
;
2771 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2774 max_load
= this_load
= total_load
= total_pwr
= 0;
2775 busiest_load_per_task
= busiest_nr_running
= 0;
2776 this_load_per_task
= this_nr_running
= 0;
2777 if (idle
== CPU_NOT_IDLE
)
2778 load_idx
= sd
->busy_idx
;
2779 else if (idle
== CPU_NEWLY_IDLE
)
2780 load_idx
= sd
->newidle_idx
;
2782 load_idx
= sd
->idle_idx
;
2785 unsigned long load
, group_capacity
, max_cpu_load
, min_cpu_load
;
2788 int __group_imb
= 0;
2789 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2790 unsigned long sum_nr_running
, sum_weighted_load
;
2792 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2795 balance_cpu
= first_cpu(group
->cpumask
);
2797 /* Tally up the load of all CPUs in the group */
2798 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2800 min_cpu_load
= ~0UL;
2802 for_each_cpu_mask(i
, group
->cpumask
) {
2805 if (!cpu_isset(i
, *cpus
))
2810 if (*sd_idle
&& rq
->nr_running
)
2813 /* Bias balancing toward cpus of our domain */
2815 if (idle_cpu(i
) && !first_idle_cpu
) {
2820 load
= target_load(i
, load_idx
);
2822 load
= source_load(i
, load_idx
);
2823 if (load
> max_cpu_load
)
2824 max_cpu_load
= load
;
2825 if (min_cpu_load
> load
)
2826 min_cpu_load
= load
;
2830 sum_nr_running
+= rq
->nr_running
;
2831 sum_weighted_load
+= weighted_cpuload(i
);
2835 * First idle cpu or the first cpu(busiest) in this sched group
2836 * is eligible for doing load balancing at this and above
2837 * domains. In the newly idle case, we will allow all the cpu's
2838 * to do the newly idle load balance.
2840 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2841 balance_cpu
!= this_cpu
&& balance
) {
2846 total_load
+= avg_load
;
2847 total_pwr
+= group
->__cpu_power
;
2849 /* Adjust by relative CPU power of the group */
2850 avg_load
= sg_div_cpu_power(group
,
2851 avg_load
* SCHED_LOAD_SCALE
);
2853 if ((max_cpu_load
- min_cpu_load
) > SCHED_LOAD_SCALE
)
2856 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2859 this_load
= avg_load
;
2861 this_nr_running
= sum_nr_running
;
2862 this_load_per_task
= sum_weighted_load
;
2863 } else if (avg_load
> max_load
&&
2864 (sum_nr_running
> group_capacity
|| __group_imb
)) {
2865 max_load
= avg_load
;
2867 busiest_nr_running
= sum_nr_running
;
2868 busiest_load_per_task
= sum_weighted_load
;
2869 group_imb
= __group_imb
;
2872 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2874 * Busy processors will not participate in power savings
2877 if (idle
== CPU_NOT_IDLE
||
2878 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2882 * If the local group is idle or completely loaded
2883 * no need to do power savings balance at this domain
2885 if (local_group
&& (this_nr_running
>= group_capacity
||
2887 power_savings_balance
= 0;
2890 * If a group is already running at full capacity or idle,
2891 * don't include that group in power savings calculations
2893 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2898 * Calculate the group which has the least non-idle load.
2899 * This is the group from where we need to pick up the load
2902 if ((sum_nr_running
< min_nr_running
) ||
2903 (sum_nr_running
== min_nr_running
&&
2904 first_cpu(group
->cpumask
) <
2905 first_cpu(group_min
->cpumask
))) {
2907 min_nr_running
= sum_nr_running
;
2908 min_load_per_task
= sum_weighted_load
/
2913 * Calculate the group which is almost near its
2914 * capacity but still has some space to pick up some load
2915 * from other group and save more power
2917 if (sum_nr_running
<= group_capacity
- 1) {
2918 if (sum_nr_running
> leader_nr_running
||
2919 (sum_nr_running
== leader_nr_running
&&
2920 first_cpu(group
->cpumask
) >
2921 first_cpu(group_leader
->cpumask
))) {
2922 group_leader
= group
;
2923 leader_nr_running
= sum_nr_running
;
2928 group
= group
->next
;
2929 } while (group
!= sd
->groups
);
2931 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2934 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2936 if (this_load
>= avg_load
||
2937 100*max_load
<= sd
->imbalance_pct
*this_load
)
2940 busiest_load_per_task
/= busiest_nr_running
;
2942 busiest_load_per_task
= min(busiest_load_per_task
, avg_load
);
2945 * We're trying to get all the cpus to the average_load, so we don't
2946 * want to push ourselves above the average load, nor do we wish to
2947 * reduce the max loaded cpu below the average load, as either of these
2948 * actions would just result in more rebalancing later, and ping-pong
2949 * tasks around. Thus we look for the minimum possible imbalance.
2950 * Negative imbalances (*we* are more loaded than anyone else) will
2951 * be counted as no imbalance for these purposes -- we can't fix that
2952 * by pulling tasks to us. Be careful of negative numbers as they'll
2953 * appear as very large values with unsigned longs.
2955 if (max_load
<= busiest_load_per_task
)
2959 * In the presence of smp nice balancing, certain scenarios can have
2960 * max load less than avg load(as we skip the groups at or below
2961 * its cpu_power, while calculating max_load..)
2963 if (max_load
< avg_load
) {
2965 goto small_imbalance
;
2968 /* Don't want to pull so many tasks that a group would go idle */
2969 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2971 /* How much load to actually move to equalise the imbalance */
2972 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2973 (avg_load
- this_load
) * this->__cpu_power
)
2977 * if *imbalance is less than the average load per runnable task
2978 * there is no gaurantee that any tasks will be moved so we'll have
2979 * a think about bumping its value to force at least one task to be
2982 if (*imbalance
< busiest_load_per_task
) {
2983 unsigned long tmp
, pwr_now
, pwr_move
;
2987 pwr_move
= pwr_now
= 0;
2989 if (this_nr_running
) {
2990 this_load_per_task
/= this_nr_running
;
2991 if (busiest_load_per_task
> this_load_per_task
)
2994 this_load_per_task
= SCHED_LOAD_SCALE
;
2996 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
2997 busiest_load_per_task
* imbn
) {
2998 *imbalance
= busiest_load_per_task
;
3003 * OK, we don't have enough imbalance to justify moving tasks,
3004 * however we may be able to increase total CPU power used by
3008 pwr_now
+= busiest
->__cpu_power
*
3009 min(busiest_load_per_task
, max_load
);
3010 pwr_now
+= this->__cpu_power
*
3011 min(this_load_per_task
, this_load
);
3012 pwr_now
/= SCHED_LOAD_SCALE
;
3014 /* Amount of load we'd subtract */
3015 tmp
= sg_div_cpu_power(busiest
,
3016 busiest_load_per_task
* SCHED_LOAD_SCALE
);
3018 pwr_move
+= busiest
->__cpu_power
*
3019 min(busiest_load_per_task
, max_load
- tmp
);
3021 /* Amount of load we'd add */
3022 if (max_load
* busiest
->__cpu_power
<
3023 busiest_load_per_task
* SCHED_LOAD_SCALE
)
3024 tmp
= sg_div_cpu_power(this,
3025 max_load
* busiest
->__cpu_power
);
3027 tmp
= sg_div_cpu_power(this,
3028 busiest_load_per_task
* SCHED_LOAD_SCALE
);
3029 pwr_move
+= this->__cpu_power
*
3030 min(this_load_per_task
, this_load
+ tmp
);
3031 pwr_move
/= SCHED_LOAD_SCALE
;
3033 /* Move if we gain throughput */
3034 if (pwr_move
> pwr_now
)
3035 *imbalance
= busiest_load_per_task
;
3041 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
3042 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
3045 if (this == group_leader
&& group_leader
!= group_min
) {
3046 *imbalance
= min_load_per_task
;
3056 * find_busiest_queue - find the busiest runqueue among the cpus in group.
3059 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
3060 unsigned long imbalance
, cpumask_t
*cpus
)
3062 struct rq
*busiest
= NULL
, *rq
;
3063 unsigned long max_load
= 0;
3066 for_each_cpu_mask(i
, group
->cpumask
) {
3069 if (!cpu_isset(i
, *cpus
))
3073 wl
= weighted_cpuload(i
);
3075 if (rq
->nr_running
== 1 && wl
> imbalance
)
3078 if (wl
> max_load
) {
3088 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
3089 * so long as it is large enough.
3091 #define MAX_PINNED_INTERVAL 512
3094 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3095 * tasks if there is an imbalance.
3097 static int load_balance(int this_cpu
, struct rq
*this_rq
,
3098 struct sched_domain
*sd
, enum cpu_idle_type idle
,
3101 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
3102 struct sched_group
*group
;
3103 unsigned long imbalance
;
3105 cpumask_t cpus
= CPU_MASK_ALL
;
3106 unsigned long flags
;
3109 * When power savings policy is enabled for the parent domain, idle
3110 * sibling can pick up load irrespective of busy siblings. In this case,
3111 * let the state of idle sibling percolate up as CPU_IDLE, instead of
3112 * portraying it as CPU_NOT_IDLE.
3114 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3115 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3118 schedstat_inc(sd
, lb_count
[idle
]);
3121 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
3128 schedstat_inc(sd
, lb_nobusyg
[idle
]);
3132 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
3134 schedstat_inc(sd
, lb_nobusyq
[idle
]);
3138 BUG_ON(busiest
== this_rq
);
3140 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
3143 if (busiest
->nr_running
> 1) {
3145 * Attempt to move tasks. If find_busiest_group has found
3146 * an imbalance but busiest->nr_running <= 1, the group is
3147 * still unbalanced. ld_moved simply stays zero, so it is
3148 * correctly treated as an imbalance.
3150 local_irq_save(flags
);
3151 double_rq_lock(this_rq
, busiest
);
3152 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
3153 imbalance
, sd
, idle
, &all_pinned
);
3154 double_rq_unlock(this_rq
, busiest
);
3155 local_irq_restore(flags
);
3158 * some other cpu did the load balance for us.
3160 if (ld_moved
&& this_cpu
!= smp_processor_id())
3161 resched_cpu(this_cpu
);
3163 /* All tasks on this runqueue were pinned by CPU affinity */
3164 if (unlikely(all_pinned
)) {
3165 cpu_clear(cpu_of(busiest
), cpus
);
3166 if (!cpus_empty(cpus
))
3173 schedstat_inc(sd
, lb_failed
[idle
]);
3174 sd
->nr_balance_failed
++;
3176 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
3178 spin_lock_irqsave(&busiest
->lock
, flags
);
3180 /* don't kick the migration_thread, if the curr
3181 * task on busiest cpu can't be moved to this_cpu
3183 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
3184 spin_unlock_irqrestore(&busiest
->lock
, flags
);
3186 goto out_one_pinned
;
3189 if (!busiest
->active_balance
) {
3190 busiest
->active_balance
= 1;
3191 busiest
->push_cpu
= this_cpu
;
3194 spin_unlock_irqrestore(&busiest
->lock
, flags
);
3196 wake_up_process(busiest
->migration_thread
);
3199 * We've kicked active balancing, reset the failure
3202 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
3205 sd
->nr_balance_failed
= 0;
3207 if (likely(!active_balance
)) {
3208 /* We were unbalanced, so reset the balancing interval */
3209 sd
->balance_interval
= sd
->min_interval
;
3212 * If we've begun active balancing, start to back off. This
3213 * case may not be covered by the all_pinned logic if there
3214 * is only 1 task on the busy runqueue (because we don't call
3217 if (sd
->balance_interval
< sd
->max_interval
)
3218 sd
->balance_interval
*= 2;
3221 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3222 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3227 schedstat_inc(sd
, lb_balanced
[idle
]);
3229 sd
->nr_balance_failed
= 0;
3232 /* tune up the balancing interval */
3233 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
3234 (sd
->balance_interval
< sd
->max_interval
))
3235 sd
->balance_interval
*= 2;
3237 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3238 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3244 * Check this_cpu to ensure it is balanced within domain. Attempt to move
3245 * tasks if there is an imbalance.
3247 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
3248 * this_rq is locked.
3251 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
3253 struct sched_group
*group
;
3254 struct rq
*busiest
= NULL
;
3255 unsigned long imbalance
;
3259 cpumask_t cpus
= CPU_MASK_ALL
;
3262 * When power savings policy is enabled for the parent domain, idle
3263 * sibling can pick up load irrespective of busy siblings. In this case,
3264 * let the state of idle sibling percolate up as IDLE, instead of
3265 * portraying it as CPU_NOT_IDLE.
3267 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
3268 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3271 schedstat_inc(sd
, lb_count
[CPU_NEWLY_IDLE
]);
3273 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
3274 &sd_idle
, &cpus
, NULL
);
3276 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
3280 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
3283 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
3287 BUG_ON(busiest
== this_rq
);
3289 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
3292 if (busiest
->nr_running
> 1) {
3293 /* Attempt to move tasks */
3294 double_lock_balance(this_rq
, busiest
);
3295 /* this_rq->clock is already updated */
3296 update_rq_clock(busiest
);
3297 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
3298 imbalance
, sd
, CPU_NEWLY_IDLE
,
3300 spin_unlock(&busiest
->lock
);
3302 if (unlikely(all_pinned
)) {
3303 cpu_clear(cpu_of(busiest
), cpus
);
3304 if (!cpus_empty(cpus
))
3310 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
3311 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3312 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3315 sd
->nr_balance_failed
= 0;
3320 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
3321 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
3322 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
3324 sd
->nr_balance_failed
= 0;
3330 * idle_balance is called by schedule() if this_cpu is about to become
3331 * idle. Attempts to pull tasks from other CPUs.
3333 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
3335 struct sched_domain
*sd
;
3336 int pulled_task
= -1;
3337 unsigned long next_balance
= jiffies
+ HZ
;
3339 for_each_domain(this_cpu
, sd
) {
3340 unsigned long interval
;
3342 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3345 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
3346 /* If we've pulled tasks over stop searching: */
3347 pulled_task
= load_balance_newidle(this_cpu
,
3350 interval
= msecs_to_jiffies(sd
->balance_interval
);
3351 if (time_after(next_balance
, sd
->last_balance
+ interval
))
3352 next_balance
= sd
->last_balance
+ interval
;
3356 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
3358 * We are going idle. next_balance may be set based on
3359 * a busy processor. So reset next_balance.
3361 this_rq
->next_balance
= next_balance
;
3366 * active_load_balance is run by migration threads. It pushes running tasks
3367 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
3368 * running on each physical CPU where possible, and avoids physical /
3369 * logical imbalances.
3371 * Called with busiest_rq locked.
3373 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
3375 int target_cpu
= busiest_rq
->push_cpu
;
3376 struct sched_domain
*sd
;
3377 struct rq
*target_rq
;
3379 /* Is there any task to move? */
3380 if (busiest_rq
->nr_running
<= 1)
3383 target_rq
= cpu_rq(target_cpu
);
3386 * This condition is "impossible", if it occurs
3387 * we need to fix it. Originally reported by
3388 * Bjorn Helgaas on a 128-cpu setup.
3390 BUG_ON(busiest_rq
== target_rq
);
3392 /* move a task from busiest_rq to target_rq */
3393 double_lock_balance(busiest_rq
, target_rq
);
3394 update_rq_clock(busiest_rq
);
3395 update_rq_clock(target_rq
);
3397 /* Search for an sd spanning us and the target CPU. */
3398 for_each_domain(target_cpu
, sd
) {
3399 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
3400 cpu_isset(busiest_cpu
, sd
->span
))
3405 schedstat_inc(sd
, alb_count
);
3407 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
3409 schedstat_inc(sd
, alb_pushed
);
3411 schedstat_inc(sd
, alb_failed
);
3413 spin_unlock(&target_rq
->lock
);
3418 atomic_t load_balancer
;
3420 } nohz ____cacheline_aligned
= {
3421 .load_balancer
= ATOMIC_INIT(-1),
3422 .cpu_mask
= CPU_MASK_NONE
,
3426 * This routine will try to nominate the ilb (idle load balancing)
3427 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3428 * load balancing on behalf of all those cpus. If all the cpus in the system
3429 * go into this tickless mode, then there will be no ilb owner (as there is
3430 * no need for one) and all the cpus will sleep till the next wakeup event
3433 * For the ilb owner, tick is not stopped. And this tick will be used
3434 * for idle load balancing. ilb owner will still be part of
3437 * While stopping the tick, this cpu will become the ilb owner if there
3438 * is no other owner. And will be the owner till that cpu becomes busy
3439 * or if all cpus in the system stop their ticks at which point
3440 * there is no need for ilb owner.
3442 * When the ilb owner becomes busy, it nominates another owner, during the
3443 * next busy scheduler_tick()
3445 int select_nohz_load_balancer(int stop_tick
)
3447 int cpu
= smp_processor_id();
3450 cpu_set(cpu
, nohz
.cpu_mask
);
3451 cpu_rq(cpu
)->in_nohz_recently
= 1;
3454 * If we are going offline and still the leader, give up!
3456 if (cpu_is_offline(cpu
) &&
3457 atomic_read(&nohz
.load_balancer
) == cpu
) {
3458 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3463 /* time for ilb owner also to sleep */
3464 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3465 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3466 atomic_set(&nohz
.load_balancer
, -1);
3470 if (atomic_read(&nohz
.load_balancer
) == -1) {
3471 /* make me the ilb owner */
3472 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
3474 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
3477 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
3480 cpu_clear(cpu
, nohz
.cpu_mask
);
3482 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3483 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3490 static DEFINE_SPINLOCK(balancing
);
3493 * It checks each scheduling domain to see if it is due to be balanced,
3494 * and initiates a balancing operation if so.
3496 * Balancing parameters are set up in arch_init_sched_domains.
3498 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3501 struct rq
*rq
= cpu_rq(cpu
);
3502 unsigned long interval
;
3503 struct sched_domain
*sd
;
3504 /* Earliest time when we have to do rebalance again */
3505 unsigned long next_balance
= jiffies
+ 60*HZ
;
3506 int update_next_balance
= 0;
3508 for_each_domain(cpu
, sd
) {
3509 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3512 interval
= sd
->balance_interval
;
3513 if (idle
!= CPU_IDLE
)
3514 interval
*= sd
->busy_factor
;
3516 /* scale ms to jiffies */
3517 interval
= msecs_to_jiffies(interval
);
3518 if (unlikely(!interval
))
3520 if (interval
> HZ
*NR_CPUS
/10)
3521 interval
= HZ
*NR_CPUS
/10;
3524 if (sd
->flags
& SD_SERIALIZE
) {
3525 if (!spin_trylock(&balancing
))
3529 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3530 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3532 * We've pulled tasks over so either we're no
3533 * longer idle, or one of our SMT siblings is
3536 idle
= CPU_NOT_IDLE
;
3538 sd
->last_balance
= jiffies
;
3540 if (sd
->flags
& SD_SERIALIZE
)
3541 spin_unlock(&balancing
);
3543 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3544 next_balance
= sd
->last_balance
+ interval
;
3545 update_next_balance
= 1;
3549 * Stop the load balance at this level. There is another
3550 * CPU in our sched group which is doing load balancing more
3558 * next_balance will be updated only when there is a need.
3559 * When the cpu is attached to null domain for ex, it will not be
3562 if (likely(update_next_balance
))
3563 rq
->next_balance
= next_balance
;
3567 * run_rebalance_domains is triggered when needed from the scheduler tick.
3568 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3569 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3571 static void run_rebalance_domains(struct softirq_action
*h
)
3573 int this_cpu
= smp_processor_id();
3574 struct rq
*this_rq
= cpu_rq(this_cpu
);
3575 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3576 CPU_IDLE
: CPU_NOT_IDLE
;
3578 rebalance_domains(this_cpu
, idle
);
3582 * If this cpu is the owner for idle load balancing, then do the
3583 * balancing on behalf of the other idle cpus whose ticks are
3586 if (this_rq
->idle_at_tick
&&
3587 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3588 cpumask_t cpus
= nohz
.cpu_mask
;
3592 cpu_clear(this_cpu
, cpus
);
3593 for_each_cpu_mask(balance_cpu
, cpus
) {
3595 * If this cpu gets work to do, stop the load balancing
3596 * work being done for other cpus. Next load
3597 * balancing owner will pick it up.
3602 rebalance_domains(balance_cpu
, CPU_IDLE
);
3604 rq
= cpu_rq(balance_cpu
);
3605 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3606 this_rq
->next_balance
= rq
->next_balance
;
3613 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3615 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3616 * idle load balancing owner or decide to stop the periodic load balancing,
3617 * if the whole system is idle.
3619 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3623 * If we were in the nohz mode recently and busy at the current
3624 * scheduler tick, then check if we need to nominate new idle
3627 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3628 rq
->in_nohz_recently
= 0;
3630 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3631 cpu_clear(cpu
, nohz
.cpu_mask
);
3632 atomic_set(&nohz
.load_balancer
, -1);
3635 if (atomic_read(&nohz
.load_balancer
) == -1) {
3637 * simple selection for now: Nominate the
3638 * first cpu in the nohz list to be the next
3641 * TBD: Traverse the sched domains and nominate
3642 * the nearest cpu in the nohz.cpu_mask.
3644 int ilb
= first_cpu(nohz
.cpu_mask
);
3652 * If this cpu is idle and doing idle load balancing for all the
3653 * cpus with ticks stopped, is it time for that to stop?
3655 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3656 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3662 * If this cpu is idle and the idle load balancing is done by
3663 * someone else, then no need raise the SCHED_SOFTIRQ
3665 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3666 cpu_isset(cpu
, nohz
.cpu_mask
))
3669 if (time_after_eq(jiffies
, rq
->next_balance
))
3670 raise_softirq(SCHED_SOFTIRQ
);
3673 #else /* CONFIG_SMP */
3676 * on UP we do not need to balance between CPUs:
3678 static inline void idle_balance(int cpu
, struct rq
*rq
)
3684 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3686 EXPORT_PER_CPU_SYMBOL(kstat
);
3689 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3690 * that have not yet been banked in case the task is currently running.
3692 unsigned long long task_sched_runtime(struct task_struct
*p
)
3694 unsigned long flags
;
3698 rq
= task_rq_lock(p
, &flags
);
3699 ns
= p
->se
.sum_exec_runtime
;
3700 if (task_current(rq
, p
)) {
3701 update_rq_clock(rq
);
3702 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3703 if ((s64
)delta_exec
> 0)
3706 task_rq_unlock(rq
, &flags
);
3712 * Account user cpu time to a process.
3713 * @p: the process that the cpu time gets accounted to
3714 * @cputime: the cpu time spent in user space since the last update
3716 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3718 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3721 p
->utime
= cputime_add(p
->utime
, cputime
);
3723 /* Add user time to cpustat. */
3724 tmp
= cputime_to_cputime64(cputime
);
3725 if (TASK_NICE(p
) > 0)
3726 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3728 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3732 * Account guest cpu time to a process.
3733 * @p: the process that the cpu time gets accounted to
3734 * @cputime: the cpu time spent in virtual machine since the last update
3736 static void account_guest_time(struct task_struct
*p
, cputime_t cputime
)
3739 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3741 tmp
= cputime_to_cputime64(cputime
);
3743 p
->utime
= cputime_add(p
->utime
, cputime
);
3744 p
->gtime
= cputime_add(p
->gtime
, cputime
);
3746 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3747 cpustat
->guest
= cputime64_add(cpustat
->guest
, tmp
);
3751 * Account scaled user cpu time to a process.
3752 * @p: the process that the cpu time gets accounted to
3753 * @cputime: the cpu time spent in user space since the last update
3755 void account_user_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3757 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime
);
3761 * Account system cpu time to a process.
3762 * @p: the process that the cpu time gets accounted to
3763 * @hardirq_offset: the offset to subtract from hardirq_count()
3764 * @cputime: the cpu time spent in kernel space since the last update
3766 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3769 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3770 struct rq
*rq
= this_rq();
3773 if ((p
->flags
& PF_VCPU
) && (irq_count() - hardirq_offset
== 0))
3774 return account_guest_time(p
, cputime
);
3776 p
->stime
= cputime_add(p
->stime
, cputime
);
3778 /* Add system time to cpustat. */
3779 tmp
= cputime_to_cputime64(cputime
);
3780 if (hardirq_count() - hardirq_offset
)
3781 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3782 else if (softirq_count())
3783 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3784 else if (p
!= rq
->idle
)
3785 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3786 else if (atomic_read(&rq
->nr_iowait
) > 0)
3787 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3789 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3790 /* Account for system time used */
3791 acct_update_integrals(p
);
3795 * Account scaled system cpu time to a process.
3796 * @p: the process that the cpu time gets accounted to
3797 * @hardirq_offset: the offset to subtract from hardirq_count()
3798 * @cputime: the cpu time spent in kernel space since the last update
3800 void account_system_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3802 p
->stimescaled
= cputime_add(p
->stimescaled
, cputime
);
3806 * Account for involuntary wait time.
3807 * @p: the process from which the cpu time has been stolen
3808 * @steal: the cpu time spent in involuntary wait
3810 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3812 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3813 cputime64_t tmp
= cputime_to_cputime64(steal
);
3814 struct rq
*rq
= this_rq();
3816 if (p
== rq
->idle
) {
3817 p
->stime
= cputime_add(p
->stime
, steal
);
3818 if (atomic_read(&rq
->nr_iowait
) > 0)
3819 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3821 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3823 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3827 * This function gets called by the timer code, with HZ frequency.
3828 * We call it with interrupts disabled.
3830 * It also gets called by the fork code, when changing the parent's
3833 void scheduler_tick(void)
3835 int cpu
= smp_processor_id();
3836 struct rq
*rq
= cpu_rq(cpu
);
3837 struct task_struct
*curr
= rq
->curr
;
3838 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3840 spin_lock(&rq
->lock
);
3841 __update_rq_clock(rq
);
3843 * Let rq->clock advance by at least TICK_NSEC:
3845 if (unlikely(rq
->clock
< next_tick
)) {
3846 rq
->clock
= next_tick
;
3847 rq
->clock_underflows
++;
3849 rq
->tick_timestamp
= rq
->clock
;
3850 update_last_tick_seen(rq
);
3851 update_cpu_load(rq
);
3852 curr
->sched_class
->task_tick(rq
, curr
, 0);
3853 update_sched_rt_period(rq
);
3854 spin_unlock(&rq
->lock
);
3857 rq
->idle_at_tick
= idle_cpu(cpu
);
3858 trigger_load_balance(rq
, cpu
);
3862 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3864 void __kprobes
add_preempt_count(int val
)
3869 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3871 preempt_count() += val
;
3873 * Spinlock count overflowing soon?
3875 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3878 EXPORT_SYMBOL(add_preempt_count
);
3880 void __kprobes
sub_preempt_count(int val
)
3885 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3888 * Is the spinlock portion underflowing?
3890 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3891 !(preempt_count() & PREEMPT_MASK
)))
3894 preempt_count() -= val
;
3896 EXPORT_SYMBOL(sub_preempt_count
);
3901 * Print scheduling while atomic bug:
3903 static noinline
void __schedule_bug(struct task_struct
*prev
)
3905 struct pt_regs
*regs
= get_irq_regs();
3907 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3908 prev
->comm
, prev
->pid
, preempt_count());
3910 debug_show_held_locks(prev
);
3911 if (irqs_disabled())
3912 print_irqtrace_events(prev
);
3921 * Various schedule()-time debugging checks and statistics:
3923 static inline void schedule_debug(struct task_struct
*prev
)
3926 * Test if we are atomic. Since do_exit() needs to call into
3927 * schedule() atomically, we ignore that path for now.
3928 * Otherwise, whine if we are scheduling when we should not be.
3930 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3931 __schedule_bug(prev
);
3933 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3935 schedstat_inc(this_rq(), sched_count
);
3936 #ifdef CONFIG_SCHEDSTATS
3937 if (unlikely(prev
->lock_depth
>= 0)) {
3938 schedstat_inc(this_rq(), bkl_count
);
3939 schedstat_inc(prev
, sched_info
.bkl_count
);
3945 * Pick up the highest-prio task:
3947 static inline struct task_struct
*
3948 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3950 const struct sched_class
*class;
3951 struct task_struct
*p
;
3954 * Optimization: we know that if all tasks are in
3955 * the fair class we can call that function directly:
3957 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3958 p
= fair_sched_class
.pick_next_task(rq
);
3963 class = sched_class_highest
;
3965 p
= class->pick_next_task(rq
);
3969 * Will never be NULL as the idle class always
3970 * returns a non-NULL p:
3972 class = class->next
;
3977 * schedule() is the main scheduler function.
3979 asmlinkage
void __sched
schedule(void)
3981 struct task_struct
*prev
, *next
;
3982 unsigned long *switch_count
;
3988 cpu
= smp_processor_id();
3992 switch_count
= &prev
->nivcsw
;
3994 release_kernel_lock(prev
);
3995 need_resched_nonpreemptible
:
3997 schedule_debug(prev
);
4002 * Do the rq-clock update outside the rq lock:
4004 local_irq_disable();
4005 __update_rq_clock(rq
);
4006 spin_lock(&rq
->lock
);
4007 clear_tsk_need_resched(prev
);
4009 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
4010 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
4011 signal_pending(prev
))) {
4012 prev
->state
= TASK_RUNNING
;
4014 deactivate_task(rq
, prev
, 1);
4016 switch_count
= &prev
->nvcsw
;
4020 if (prev
->sched_class
->pre_schedule
)
4021 prev
->sched_class
->pre_schedule(rq
, prev
);
4024 if (unlikely(!rq
->nr_running
))
4025 idle_balance(cpu
, rq
);
4027 prev
->sched_class
->put_prev_task(rq
, prev
);
4028 next
= pick_next_task(rq
, prev
);
4030 sched_info_switch(prev
, next
);
4032 if (likely(prev
!= next
)) {
4037 context_switch(rq
, prev
, next
); /* unlocks the rq */
4039 * the context switch might have flipped the stack from under
4040 * us, hence refresh the local variables.
4042 cpu
= smp_processor_id();
4045 spin_unlock_irq(&rq
->lock
);
4049 if (unlikely(reacquire_kernel_lock(current
) < 0))
4050 goto need_resched_nonpreemptible
;
4052 preempt_enable_no_resched();
4053 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
4056 EXPORT_SYMBOL(schedule
);
4058 #ifdef CONFIG_PREEMPT
4060 * this is the entry point to schedule() from in-kernel preemption
4061 * off of preempt_enable. Kernel preemptions off return from interrupt
4062 * occur there and call schedule directly.
4064 asmlinkage
void __sched
preempt_schedule(void)
4066 struct thread_info
*ti
= current_thread_info();
4067 struct task_struct
*task
= current
;
4068 int saved_lock_depth
;
4071 * If there is a non-zero preempt_count or interrupts are disabled,
4072 * we do not want to preempt the current task. Just return..
4074 if (likely(ti
->preempt_count
|| irqs_disabled()))
4078 add_preempt_count(PREEMPT_ACTIVE
);
4081 * We keep the big kernel semaphore locked, but we
4082 * clear ->lock_depth so that schedule() doesnt
4083 * auto-release the semaphore:
4085 saved_lock_depth
= task
->lock_depth
;
4086 task
->lock_depth
= -1;
4088 task
->lock_depth
= saved_lock_depth
;
4089 sub_preempt_count(PREEMPT_ACTIVE
);
4092 * Check again in case we missed a preemption opportunity
4093 * between schedule and now.
4096 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
4098 EXPORT_SYMBOL(preempt_schedule
);
4101 * this is the entry point to schedule() from kernel preemption
4102 * off of irq context.
4103 * Note, that this is called and return with irqs disabled. This will
4104 * protect us against recursive calling from irq.
4106 asmlinkage
void __sched
preempt_schedule_irq(void)
4108 struct thread_info
*ti
= current_thread_info();
4109 struct task_struct
*task
= current
;
4110 int saved_lock_depth
;
4112 /* Catch callers which need to be fixed */
4113 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
4116 add_preempt_count(PREEMPT_ACTIVE
);
4119 * We keep the big kernel semaphore locked, but we
4120 * clear ->lock_depth so that schedule() doesnt
4121 * auto-release the semaphore:
4123 saved_lock_depth
= task
->lock_depth
;
4124 task
->lock_depth
= -1;
4127 local_irq_disable();
4128 task
->lock_depth
= saved_lock_depth
;
4129 sub_preempt_count(PREEMPT_ACTIVE
);
4132 * Check again in case we missed a preemption opportunity
4133 * between schedule and now.
4136 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
4139 #endif /* CONFIG_PREEMPT */
4141 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
4144 return try_to_wake_up(curr
->private, mode
, sync
);
4146 EXPORT_SYMBOL(default_wake_function
);
4149 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4150 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4151 * number) then we wake all the non-exclusive tasks and one exclusive task.
4153 * There are circumstances in which we can try to wake a task which has already
4154 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4155 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4157 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
4158 int nr_exclusive
, int sync
, void *key
)
4160 wait_queue_t
*curr
, *next
;
4162 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
4163 unsigned flags
= curr
->flags
;
4165 if (curr
->func(curr
, mode
, sync
, key
) &&
4166 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
4172 * __wake_up - wake up threads blocked on a waitqueue.
4174 * @mode: which threads
4175 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4176 * @key: is directly passed to the wakeup function
4178 void __wake_up(wait_queue_head_t
*q
, unsigned int mode
,
4179 int nr_exclusive
, void *key
)
4181 unsigned long flags
;
4183 spin_lock_irqsave(&q
->lock
, flags
);
4184 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
4185 spin_unlock_irqrestore(&q
->lock
, flags
);
4187 EXPORT_SYMBOL(__wake_up
);
4190 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4192 void __wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
4194 __wake_up_common(q
, mode
, 1, 0, NULL
);
4198 * __wake_up_sync - wake up threads blocked on a waitqueue.
4200 * @mode: which threads
4201 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4203 * The sync wakeup differs that the waker knows that it will schedule
4204 * away soon, so while the target thread will be woken up, it will not
4205 * be migrated to another CPU - ie. the two threads are 'synchronized'
4206 * with each other. This can prevent needless bouncing between CPUs.
4208 * On UP it can prevent extra preemption.
4211 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
4213 unsigned long flags
;
4219 if (unlikely(!nr_exclusive
))
4222 spin_lock_irqsave(&q
->lock
, flags
);
4223 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
4224 spin_unlock_irqrestore(&q
->lock
, flags
);
4226 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
4228 void complete(struct completion
*x
)
4230 unsigned long flags
;
4232 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4234 __wake_up_common(&x
->wait
, TASK_NORMAL
, 1, 0, NULL
);
4235 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4237 EXPORT_SYMBOL(complete
);
4239 void complete_all(struct completion
*x
)
4241 unsigned long flags
;
4243 spin_lock_irqsave(&x
->wait
.lock
, flags
);
4244 x
->done
+= UINT_MAX
/2;
4245 __wake_up_common(&x
->wait
, TASK_NORMAL
, 0, 0, NULL
);
4246 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
4248 EXPORT_SYMBOL(complete_all
);
4250 static inline long __sched
4251 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
4254 DECLARE_WAITQUEUE(wait
, current
);
4256 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
4257 __add_wait_queue_tail(&x
->wait
, &wait
);
4259 if ((state
== TASK_INTERRUPTIBLE
&&
4260 signal_pending(current
)) ||
4261 (state
== TASK_KILLABLE
&&
4262 fatal_signal_pending(current
))) {
4263 __remove_wait_queue(&x
->wait
, &wait
);
4264 return -ERESTARTSYS
;
4266 __set_current_state(state
);
4267 spin_unlock_irq(&x
->wait
.lock
);
4268 timeout
= schedule_timeout(timeout
);
4269 spin_lock_irq(&x
->wait
.lock
);
4271 __remove_wait_queue(&x
->wait
, &wait
);
4275 __remove_wait_queue(&x
->wait
, &wait
);
4282 wait_for_common(struct completion
*x
, long timeout
, int state
)
4286 spin_lock_irq(&x
->wait
.lock
);
4287 timeout
= do_wait_for_common(x
, timeout
, state
);
4288 spin_unlock_irq(&x
->wait
.lock
);
4292 void __sched
wait_for_completion(struct completion
*x
)
4294 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
4296 EXPORT_SYMBOL(wait_for_completion
);
4298 unsigned long __sched
4299 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
4301 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
4303 EXPORT_SYMBOL(wait_for_completion_timeout
);
4305 int __sched
wait_for_completion_interruptible(struct completion
*x
)
4307 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
4308 if (t
== -ERESTARTSYS
)
4312 EXPORT_SYMBOL(wait_for_completion_interruptible
);
4314 unsigned long __sched
4315 wait_for_completion_interruptible_timeout(struct completion
*x
,
4316 unsigned long timeout
)
4318 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
4320 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
4322 int __sched
wait_for_completion_killable(struct completion
*x
)
4324 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_KILLABLE
);
4325 if (t
== -ERESTARTSYS
)
4329 EXPORT_SYMBOL(wait_for_completion_killable
);
4332 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
4334 unsigned long flags
;
4337 init_waitqueue_entry(&wait
, current
);
4339 __set_current_state(state
);
4341 spin_lock_irqsave(&q
->lock
, flags
);
4342 __add_wait_queue(q
, &wait
);
4343 spin_unlock(&q
->lock
);
4344 timeout
= schedule_timeout(timeout
);
4345 spin_lock_irq(&q
->lock
);
4346 __remove_wait_queue(q
, &wait
);
4347 spin_unlock_irqrestore(&q
->lock
, flags
);
4352 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
4354 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4356 EXPORT_SYMBOL(interruptible_sleep_on
);
4359 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4361 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
4363 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
4365 void __sched
sleep_on(wait_queue_head_t
*q
)
4367 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4369 EXPORT_SYMBOL(sleep_on
);
4371 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4373 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
4375 EXPORT_SYMBOL(sleep_on_timeout
);
4377 #ifdef CONFIG_RT_MUTEXES
4380 * rt_mutex_setprio - set the current priority of a task
4382 * @prio: prio value (kernel-internal form)
4384 * This function changes the 'effective' priority of a task. It does
4385 * not touch ->normal_prio like __setscheduler().
4387 * Used by the rt_mutex code to implement priority inheritance logic.
4389 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
4391 unsigned long flags
;
4392 int oldprio
, on_rq
, running
;
4394 const struct sched_class
*prev_class
= p
->sched_class
;
4396 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4398 rq
= task_rq_lock(p
, &flags
);
4399 update_rq_clock(rq
);
4402 on_rq
= p
->se
.on_rq
;
4403 running
= task_current(rq
, p
);
4405 dequeue_task(rq
, p
, 0);
4407 p
->sched_class
->put_prev_task(rq
, p
);
4410 p
->sched_class
= &rt_sched_class
;
4412 p
->sched_class
= &fair_sched_class
;
4417 p
->sched_class
->set_curr_task(rq
);
4419 enqueue_task(rq
, p
, 0);
4421 check_class_changed(rq
, p
, prev_class
, oldprio
, running
);
4423 task_rq_unlock(rq
, &flags
);
4428 void set_user_nice(struct task_struct
*p
, long nice
)
4430 int old_prio
, delta
, on_rq
;
4431 unsigned long flags
;
4434 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4437 * We have to be careful, if called from sys_setpriority(),
4438 * the task might be in the middle of scheduling on another CPU.
4440 rq
= task_rq_lock(p
, &flags
);
4441 update_rq_clock(rq
);
4443 * The RT priorities are set via sched_setscheduler(), but we still
4444 * allow the 'normal' nice value to be set - but as expected
4445 * it wont have any effect on scheduling until the task is
4446 * SCHED_FIFO/SCHED_RR:
4448 if (task_has_rt_policy(p
)) {
4449 p
->static_prio
= NICE_TO_PRIO(nice
);
4452 on_rq
= p
->se
.on_rq
;
4454 dequeue_task(rq
, p
, 0);
4458 p
->static_prio
= NICE_TO_PRIO(nice
);
4461 p
->prio
= effective_prio(p
);
4462 delta
= p
->prio
- old_prio
;
4465 enqueue_task(rq
, p
, 0);
4468 * If the task increased its priority or is running and
4469 * lowered its priority, then reschedule its CPU:
4471 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4472 resched_task(rq
->curr
);
4475 task_rq_unlock(rq
, &flags
);
4477 EXPORT_SYMBOL(set_user_nice
);
4480 * can_nice - check if a task can reduce its nice value
4484 int can_nice(const struct task_struct
*p
, const int nice
)
4486 /* convert nice value [19,-20] to rlimit style value [1,40] */
4487 int nice_rlim
= 20 - nice
;
4489 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4490 capable(CAP_SYS_NICE
));
4493 #ifdef __ARCH_WANT_SYS_NICE
4496 * sys_nice - change the priority of the current process.
4497 * @increment: priority increment
4499 * sys_setpriority is a more generic, but much slower function that
4500 * does similar things.
4502 asmlinkage
long sys_nice(int increment
)
4507 * Setpriority might change our priority at the same moment.
4508 * We don't have to worry. Conceptually one call occurs first
4509 * and we have a single winner.
4511 if (increment
< -40)
4516 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4522 if (increment
< 0 && !can_nice(current
, nice
))
4525 retval
= security_task_setnice(current
, nice
);
4529 set_user_nice(current
, nice
);
4536 * task_prio - return the priority value of a given task.
4537 * @p: the task in question.
4539 * This is the priority value as seen by users in /proc.
4540 * RT tasks are offset by -200. Normal tasks are centered
4541 * around 0, value goes from -16 to +15.
4543 int task_prio(const struct task_struct
*p
)
4545 return p
->prio
- MAX_RT_PRIO
;
4549 * task_nice - return the nice value of a given task.
4550 * @p: the task in question.
4552 int task_nice(const struct task_struct
*p
)
4554 return TASK_NICE(p
);
4556 EXPORT_SYMBOL(task_nice
);
4559 * idle_cpu - is a given cpu idle currently?
4560 * @cpu: the processor in question.
4562 int idle_cpu(int cpu
)
4564 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4568 * idle_task - return the idle task for a given cpu.
4569 * @cpu: the processor in question.
4571 struct task_struct
*idle_task(int cpu
)
4573 return cpu_rq(cpu
)->idle
;
4577 * find_process_by_pid - find a process with a matching PID value.
4578 * @pid: the pid in question.
4580 static struct task_struct
*find_process_by_pid(pid_t pid
)
4582 return pid
? find_task_by_vpid(pid
) : current
;
4585 /* Actually do priority change: must hold rq lock. */
4587 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4589 BUG_ON(p
->se
.on_rq
);
4592 switch (p
->policy
) {
4596 p
->sched_class
= &fair_sched_class
;
4600 p
->sched_class
= &rt_sched_class
;
4604 p
->rt_priority
= prio
;
4605 p
->normal_prio
= normal_prio(p
);
4606 /* we are holding p->pi_lock already */
4607 p
->prio
= rt_mutex_getprio(p
);
4612 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4613 * @p: the task in question.
4614 * @policy: new policy.
4615 * @param: structure containing the new RT priority.
4617 * NOTE that the task may be already dead.
4619 int sched_setscheduler(struct task_struct
*p
, int policy
,
4620 struct sched_param
*param
)
4622 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
4623 unsigned long flags
;
4624 const struct sched_class
*prev_class
= p
->sched_class
;
4627 /* may grab non-irq protected spin_locks */
4628 BUG_ON(in_interrupt());
4630 /* double check policy once rq lock held */
4632 policy
= oldpolicy
= p
->policy
;
4633 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4634 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4635 policy
!= SCHED_IDLE
)
4638 * Valid priorities for SCHED_FIFO and SCHED_RR are
4639 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4640 * SCHED_BATCH and SCHED_IDLE is 0.
4642 if (param
->sched_priority
< 0 ||
4643 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4644 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4646 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4650 * Allow unprivileged RT tasks to decrease priority:
4652 if (!capable(CAP_SYS_NICE
)) {
4653 if (rt_policy(policy
)) {
4654 unsigned long rlim_rtprio
;
4656 if (!lock_task_sighand(p
, &flags
))
4658 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4659 unlock_task_sighand(p
, &flags
);
4661 /* can't set/change the rt policy */
4662 if (policy
!= p
->policy
&& !rlim_rtprio
)
4665 /* can't increase priority */
4666 if (param
->sched_priority
> p
->rt_priority
&&
4667 param
->sched_priority
> rlim_rtprio
)
4671 * Like positive nice levels, dont allow tasks to
4672 * move out of SCHED_IDLE either:
4674 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4677 /* can't change other user's priorities */
4678 if ((current
->euid
!= p
->euid
) &&
4679 (current
->euid
!= p
->uid
))
4683 #ifdef CONFIG_RT_GROUP_SCHED
4685 * Do not allow realtime tasks into groups that have no runtime
4688 if (rt_policy(policy
) && task_group(p
)->rt_runtime
== 0)
4692 retval
= security_task_setscheduler(p
, policy
, param
);
4696 * make sure no PI-waiters arrive (or leave) while we are
4697 * changing the priority of the task:
4699 spin_lock_irqsave(&p
->pi_lock
, flags
);
4701 * To be able to change p->policy safely, the apropriate
4702 * runqueue lock must be held.
4704 rq
= __task_rq_lock(p
);
4705 /* recheck policy now with rq lock held */
4706 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4707 policy
= oldpolicy
= -1;
4708 __task_rq_unlock(rq
);
4709 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4712 update_rq_clock(rq
);
4713 on_rq
= p
->se
.on_rq
;
4714 running
= task_current(rq
, p
);
4716 deactivate_task(rq
, p
, 0);
4718 p
->sched_class
->put_prev_task(rq
, p
);
4721 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4724 p
->sched_class
->set_curr_task(rq
);
4726 activate_task(rq
, p
, 0);
4728 check_class_changed(rq
, p
, prev_class
, oldprio
, running
);
4730 __task_rq_unlock(rq
);
4731 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4733 rt_mutex_adjust_pi(p
);
4737 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4740 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4742 struct sched_param lparam
;
4743 struct task_struct
*p
;
4746 if (!param
|| pid
< 0)
4748 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4753 p
= find_process_by_pid(pid
);
4755 retval
= sched_setscheduler(p
, policy
, &lparam
);
4762 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4763 * @pid: the pid in question.
4764 * @policy: new policy.
4765 * @param: structure containing the new RT priority.
4768 sys_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4770 /* negative values for policy are not valid */
4774 return do_sched_setscheduler(pid
, policy
, param
);
4778 * sys_sched_setparam - set/change the RT priority of a thread
4779 * @pid: the pid in question.
4780 * @param: structure containing the new RT priority.
4782 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4784 return do_sched_setscheduler(pid
, -1, param
);
4788 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4789 * @pid: the pid in question.
4791 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4793 struct task_struct
*p
;
4800 read_lock(&tasklist_lock
);
4801 p
= find_process_by_pid(pid
);
4803 retval
= security_task_getscheduler(p
);
4807 read_unlock(&tasklist_lock
);
4812 * sys_sched_getscheduler - get the RT priority of a thread
4813 * @pid: the pid in question.
4814 * @param: structure containing the RT priority.
4816 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4818 struct sched_param lp
;
4819 struct task_struct
*p
;
4822 if (!param
|| pid
< 0)
4825 read_lock(&tasklist_lock
);
4826 p
= find_process_by_pid(pid
);
4831 retval
= security_task_getscheduler(p
);
4835 lp
.sched_priority
= p
->rt_priority
;
4836 read_unlock(&tasklist_lock
);
4839 * This one might sleep, we cannot do it with a spinlock held ...
4841 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4846 read_unlock(&tasklist_lock
);
4850 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4852 cpumask_t cpus_allowed
;
4853 struct task_struct
*p
;
4857 read_lock(&tasklist_lock
);
4859 p
= find_process_by_pid(pid
);
4861 read_unlock(&tasklist_lock
);
4867 * It is not safe to call set_cpus_allowed with the
4868 * tasklist_lock held. We will bump the task_struct's
4869 * usage count and then drop tasklist_lock.
4872 read_unlock(&tasklist_lock
);
4875 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4876 !capable(CAP_SYS_NICE
))
4879 retval
= security_task_setscheduler(p
, 0, NULL
);
4883 cpus_allowed
= cpuset_cpus_allowed(p
);
4884 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4886 retval
= set_cpus_allowed(p
, new_mask
);
4889 cpus_allowed
= cpuset_cpus_allowed(p
);
4890 if (!cpus_subset(new_mask
, cpus_allowed
)) {
4892 * We must have raced with a concurrent cpuset
4893 * update. Just reset the cpus_allowed to the
4894 * cpuset's cpus_allowed
4896 new_mask
= cpus_allowed
;
4906 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4907 cpumask_t
*new_mask
)
4909 if (len
< sizeof(cpumask_t
)) {
4910 memset(new_mask
, 0, sizeof(cpumask_t
));
4911 } else if (len
> sizeof(cpumask_t
)) {
4912 len
= sizeof(cpumask_t
);
4914 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4918 * sys_sched_setaffinity - set the cpu affinity of a process
4919 * @pid: pid of the process
4920 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4921 * @user_mask_ptr: user-space pointer to the new cpu mask
4923 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4924 unsigned long __user
*user_mask_ptr
)
4929 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4933 return sched_setaffinity(pid
, new_mask
);
4937 * Represents all cpu's present in the system
4938 * In systems capable of hotplug, this map could dynamically grow
4939 * as new cpu's are detected in the system via any platform specific
4940 * method, such as ACPI for e.g.
4943 cpumask_t cpu_present_map __read_mostly
;
4944 EXPORT_SYMBOL(cpu_present_map
);
4947 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4948 EXPORT_SYMBOL(cpu_online_map
);
4950 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4951 EXPORT_SYMBOL(cpu_possible_map
);
4954 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4956 struct task_struct
*p
;
4960 read_lock(&tasklist_lock
);
4963 p
= find_process_by_pid(pid
);
4967 retval
= security_task_getscheduler(p
);
4971 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4974 read_unlock(&tasklist_lock
);
4981 * sys_sched_getaffinity - get the cpu affinity of a process
4982 * @pid: pid of the process
4983 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4984 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4986 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4987 unsigned long __user
*user_mask_ptr
)
4992 if (len
< sizeof(cpumask_t
))
4995 ret
= sched_getaffinity(pid
, &mask
);
4999 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
5002 return sizeof(cpumask_t
);
5006 * sys_sched_yield - yield the current processor to other threads.
5008 * This function yields the current CPU to other tasks. If there are no
5009 * other threads running on this CPU then this function will return.
5011 asmlinkage
long sys_sched_yield(void)
5013 struct rq
*rq
= this_rq_lock();
5015 schedstat_inc(rq
, yld_count
);
5016 current
->sched_class
->yield_task(rq
);
5019 * Since we are going to call schedule() anyway, there's
5020 * no need to preempt or enable interrupts:
5022 __release(rq
->lock
);
5023 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
5024 _raw_spin_unlock(&rq
->lock
);
5025 preempt_enable_no_resched();
5032 static void __cond_resched(void)
5034 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5035 __might_sleep(__FILE__
, __LINE__
);
5038 * The BKS might be reacquired before we have dropped
5039 * PREEMPT_ACTIVE, which could trigger a second
5040 * cond_resched() call.
5043 add_preempt_count(PREEMPT_ACTIVE
);
5045 sub_preempt_count(PREEMPT_ACTIVE
);
5046 } while (need_resched());
5049 #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)
5050 int __sched
_cond_resched(void)
5052 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
5053 system_state
== SYSTEM_RUNNING
) {
5059 EXPORT_SYMBOL(_cond_resched
);
5063 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
5064 * call schedule, and on return reacquire the lock.
5066 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5067 * operations here to prevent schedule() from being called twice (once via
5068 * spin_unlock(), once by hand).
5070 int cond_resched_lock(spinlock_t
*lock
)
5072 int resched
= need_resched() && system_state
== SYSTEM_RUNNING
;
5075 if (spin_needbreak(lock
) || resched
) {
5077 if (resched
&& need_resched())
5086 EXPORT_SYMBOL(cond_resched_lock
);
5088 int __sched
cond_resched_softirq(void)
5090 BUG_ON(!in_softirq());
5092 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
5100 EXPORT_SYMBOL(cond_resched_softirq
);
5103 * yield - yield the current processor to other threads.
5105 * This is a shortcut for kernel-space yielding - it marks the
5106 * thread runnable and calls sys_sched_yield().
5108 void __sched
yield(void)
5110 set_current_state(TASK_RUNNING
);
5113 EXPORT_SYMBOL(yield
);
5116 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5117 * that process accounting knows that this is a task in IO wait state.
5119 * But don't do that if it is a deliberate, throttling IO wait (this task
5120 * has set its backing_dev_info: the queue against which it should throttle)
5122 void __sched
io_schedule(void)
5124 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
5126 delayacct_blkio_start();
5127 atomic_inc(&rq
->nr_iowait
);
5129 atomic_dec(&rq
->nr_iowait
);
5130 delayacct_blkio_end();
5132 EXPORT_SYMBOL(io_schedule
);
5134 long __sched
io_schedule_timeout(long timeout
)
5136 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
5139 delayacct_blkio_start();
5140 atomic_inc(&rq
->nr_iowait
);
5141 ret
= schedule_timeout(timeout
);
5142 atomic_dec(&rq
->nr_iowait
);
5143 delayacct_blkio_end();
5148 * sys_sched_get_priority_max - return maximum RT priority.
5149 * @policy: scheduling class.
5151 * this syscall returns the maximum rt_priority that can be used
5152 * by a given scheduling class.
5154 asmlinkage
long sys_sched_get_priority_max(int policy
)
5161 ret
= MAX_USER_RT_PRIO
-1;
5173 * sys_sched_get_priority_min - return minimum RT priority.
5174 * @policy: scheduling class.
5176 * this syscall returns the minimum rt_priority that can be used
5177 * by a given scheduling class.
5179 asmlinkage
long sys_sched_get_priority_min(int policy
)
5197 * sys_sched_rr_get_interval - return the default timeslice of a process.
5198 * @pid: pid of the process.
5199 * @interval: userspace pointer to the timeslice value.
5201 * this syscall writes the default timeslice value of a given process
5202 * into the user-space timespec buffer. A value of '0' means infinity.
5205 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
5207 struct task_struct
*p
;
5208 unsigned int time_slice
;
5216 read_lock(&tasklist_lock
);
5217 p
= find_process_by_pid(pid
);
5221 retval
= security_task_getscheduler(p
);
5226 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
5227 * tasks that are on an otherwise idle runqueue:
5230 if (p
->policy
== SCHED_RR
) {
5231 time_slice
= DEF_TIMESLICE
;
5232 } else if (p
->policy
!= SCHED_FIFO
) {
5233 struct sched_entity
*se
= &p
->se
;
5234 unsigned long flags
;
5237 rq
= task_rq_lock(p
, &flags
);
5238 if (rq
->cfs
.load
.weight
)
5239 time_slice
= NS_TO_JIFFIES(sched_slice(&rq
->cfs
, se
));
5240 task_rq_unlock(rq
, &flags
);
5242 read_unlock(&tasklist_lock
);
5243 jiffies_to_timespec(time_slice
, &t
);
5244 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
5248 read_unlock(&tasklist_lock
);
5252 static const char stat_nam
[] = "RSDTtZX";
5254 void sched_show_task(struct task_struct
*p
)
5256 unsigned long free
= 0;
5259 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
5260 printk(KERN_INFO
"%-13.13s %c", p
->comm
,
5261 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
5262 #if BITS_PER_LONG == 32
5263 if (state
== TASK_RUNNING
)
5264 printk(KERN_CONT
" running ");
5266 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
5268 if (state
== TASK_RUNNING
)
5269 printk(KERN_CONT
" running task ");
5271 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
5273 #ifdef CONFIG_DEBUG_STACK_USAGE
5275 unsigned long *n
= end_of_stack(p
);
5278 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
5281 printk(KERN_CONT
"%5lu %5d %6d\n", free
,
5282 task_pid_nr(p
), task_pid_nr(p
->real_parent
));
5284 show_stack(p
, NULL
);
5287 void show_state_filter(unsigned long state_filter
)
5289 struct task_struct
*g
, *p
;
5291 #if BITS_PER_LONG == 32
5293 " task PC stack pid father\n");
5296 " task PC stack pid father\n");
5298 read_lock(&tasklist_lock
);
5299 do_each_thread(g
, p
) {
5301 * reset the NMI-timeout, listing all files on a slow
5302 * console might take alot of time:
5304 touch_nmi_watchdog();
5305 if (!state_filter
|| (p
->state
& state_filter
))
5307 } while_each_thread(g
, p
);
5309 touch_all_softlockup_watchdogs();
5311 #ifdef CONFIG_SCHED_DEBUG
5312 sysrq_sched_debug_show();
5314 read_unlock(&tasklist_lock
);
5316 * Only show locks if all tasks are dumped:
5318 if (state_filter
== -1)
5319 debug_show_all_locks();
5322 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
5324 idle
->sched_class
= &idle_sched_class
;
5328 * init_idle - set up an idle thread for a given CPU
5329 * @idle: task in question
5330 * @cpu: cpu the idle task belongs to
5332 * NOTE: this function does not set the idle thread's NEED_RESCHED
5333 * flag, to make booting more robust.
5335 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
5337 struct rq
*rq
= cpu_rq(cpu
);
5338 unsigned long flags
;
5341 idle
->se
.exec_start
= sched_clock();
5343 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
5344 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
5345 __set_task_cpu(idle
, cpu
);
5347 spin_lock_irqsave(&rq
->lock
, flags
);
5348 rq
->curr
= rq
->idle
= idle
;
5349 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5352 spin_unlock_irqrestore(&rq
->lock
, flags
);
5354 /* Set the preempt count _outside_ the spinlocks! */
5355 task_thread_info(idle
)->preempt_count
= 0;
5358 * The idle tasks have their own, simple scheduling class:
5360 idle
->sched_class
= &idle_sched_class
;
5364 * In a system that switches off the HZ timer nohz_cpu_mask
5365 * indicates which cpus entered this state. This is used
5366 * in the rcu update to wait only for active cpus. For system
5367 * which do not switch off the HZ timer nohz_cpu_mask should
5368 * always be CPU_MASK_NONE.
5370 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
5373 * Increase the granularity value when there are more CPUs,
5374 * because with more CPUs the 'effective latency' as visible
5375 * to users decreases. But the relationship is not linear,
5376 * so pick a second-best guess by going with the log2 of the
5379 * This idea comes from the SD scheduler of Con Kolivas:
5381 static inline void sched_init_granularity(void)
5383 unsigned int factor
= 1 + ilog2(num_online_cpus());
5384 const unsigned long limit
= 200000000;
5386 sysctl_sched_min_granularity
*= factor
;
5387 if (sysctl_sched_min_granularity
> limit
)
5388 sysctl_sched_min_granularity
= limit
;
5390 sysctl_sched_latency
*= factor
;
5391 if (sysctl_sched_latency
> limit
)
5392 sysctl_sched_latency
= limit
;
5394 sysctl_sched_wakeup_granularity
*= factor
;
5395 sysctl_sched_batch_wakeup_granularity
*= factor
;
5400 * This is how migration works:
5402 * 1) we queue a struct migration_req structure in the source CPU's
5403 * runqueue and wake up that CPU's migration thread.
5404 * 2) we down() the locked semaphore => thread blocks.
5405 * 3) migration thread wakes up (implicitly it forces the migrated
5406 * thread off the CPU)
5407 * 4) it gets the migration request and checks whether the migrated
5408 * task is still in the wrong runqueue.
5409 * 5) if it's in the wrong runqueue then the migration thread removes
5410 * it and puts it into the right queue.
5411 * 6) migration thread up()s the semaphore.
5412 * 7) we wake up and the migration is done.
5416 * Change a given task's CPU affinity. Migrate the thread to a
5417 * proper CPU and schedule it away if the CPU it's executing on
5418 * is removed from the allowed bitmask.
5420 * NOTE: the caller must have a valid reference to the task, the
5421 * task must not exit() & deallocate itself prematurely. The
5422 * call is not atomic; no spinlocks may be held.
5424 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5426 struct migration_req req
;
5427 unsigned long flags
;
5431 rq
= task_rq_lock(p
, &flags
);
5432 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5437 if (p
->sched_class
->set_cpus_allowed
)
5438 p
->sched_class
->set_cpus_allowed(p
, &new_mask
);
5440 p
->cpus_allowed
= new_mask
;
5441 p
->rt
.nr_cpus_allowed
= cpus_weight(new_mask
);
5444 /* Can the task run on the task's current CPU? If so, we're done */
5445 if (cpu_isset(task_cpu(p
), new_mask
))
5448 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5449 /* Need help from migration thread: drop lock and wait. */
5450 task_rq_unlock(rq
, &flags
);
5451 wake_up_process(rq
->migration_thread
);
5452 wait_for_completion(&req
.done
);
5453 tlb_migrate_finish(p
->mm
);
5457 task_rq_unlock(rq
, &flags
);
5461 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5464 * Move (not current) task off this cpu, onto dest cpu. We're doing
5465 * this because either it can't run here any more (set_cpus_allowed()
5466 * away from this CPU, or CPU going down), or because we're
5467 * attempting to rebalance this task on exec (sched_exec).
5469 * So we race with normal scheduler movements, but that's OK, as long
5470 * as the task is no longer on this CPU.
5472 * Returns non-zero if task was successfully migrated.
5474 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5476 struct rq
*rq_dest
, *rq_src
;
5479 if (unlikely(cpu_is_offline(dest_cpu
)))
5482 rq_src
= cpu_rq(src_cpu
);
5483 rq_dest
= cpu_rq(dest_cpu
);
5485 double_rq_lock(rq_src
, rq_dest
);
5486 /* Already moved. */
5487 if (task_cpu(p
) != src_cpu
)
5489 /* Affinity changed (again). */
5490 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5493 on_rq
= p
->se
.on_rq
;
5495 deactivate_task(rq_src
, p
, 0);
5497 set_task_cpu(p
, dest_cpu
);
5499 activate_task(rq_dest
, p
, 0);
5500 check_preempt_curr(rq_dest
, p
);
5504 double_rq_unlock(rq_src
, rq_dest
);
5509 * migration_thread - this is a highprio system thread that performs
5510 * thread migration by bumping thread off CPU then 'pushing' onto
5513 static int migration_thread(void *data
)
5515 int cpu
= (long)data
;
5519 BUG_ON(rq
->migration_thread
!= current
);
5521 set_current_state(TASK_INTERRUPTIBLE
);
5522 while (!kthread_should_stop()) {
5523 struct migration_req
*req
;
5524 struct list_head
*head
;
5526 spin_lock_irq(&rq
->lock
);
5528 if (cpu_is_offline(cpu
)) {
5529 spin_unlock_irq(&rq
->lock
);
5533 if (rq
->active_balance
) {
5534 active_load_balance(rq
, cpu
);
5535 rq
->active_balance
= 0;
5538 head
= &rq
->migration_queue
;
5540 if (list_empty(head
)) {
5541 spin_unlock_irq(&rq
->lock
);
5543 set_current_state(TASK_INTERRUPTIBLE
);
5546 req
= list_entry(head
->next
, struct migration_req
, list
);
5547 list_del_init(head
->next
);
5549 spin_unlock(&rq
->lock
);
5550 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5553 complete(&req
->done
);
5555 __set_current_state(TASK_RUNNING
);
5559 /* Wait for kthread_stop */
5560 set_current_state(TASK_INTERRUPTIBLE
);
5561 while (!kthread_should_stop()) {
5563 set_current_state(TASK_INTERRUPTIBLE
);
5565 __set_current_state(TASK_RUNNING
);
5569 #ifdef CONFIG_HOTPLUG_CPU
5571 static int __migrate_task_irq(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5575 local_irq_disable();
5576 ret
= __migrate_task(p
, src_cpu
, dest_cpu
);
5582 * Figure out where task on dead CPU should go, use force if necessary.
5583 * NOTE: interrupts should be disabled by the caller
5585 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5587 unsigned long flags
;
5594 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5595 cpus_and(mask
, mask
, p
->cpus_allowed
);
5596 dest_cpu
= any_online_cpu(mask
);
5598 /* On any allowed CPU? */
5599 if (dest_cpu
== NR_CPUS
)
5600 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5602 /* No more Mr. Nice Guy. */
5603 if (dest_cpu
== NR_CPUS
) {
5604 cpumask_t cpus_allowed
= cpuset_cpus_allowed_locked(p
);
5606 * Try to stay on the same cpuset, where the
5607 * current cpuset may be a subset of all cpus.
5608 * The cpuset_cpus_allowed_locked() variant of
5609 * cpuset_cpus_allowed() will not block. It must be
5610 * called within calls to cpuset_lock/cpuset_unlock.
5612 rq
= task_rq_lock(p
, &flags
);
5613 p
->cpus_allowed
= cpus_allowed
;
5614 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5615 task_rq_unlock(rq
, &flags
);
5618 * Don't tell them about moving exiting tasks or
5619 * kernel threads (both mm NULL), since they never
5622 if (p
->mm
&& printk_ratelimit()) {
5623 printk(KERN_INFO
"process %d (%s) no "
5624 "longer affine to cpu%d\n",
5625 task_pid_nr(p
), p
->comm
, dead_cpu
);
5628 } while (!__migrate_task_irq(p
, dead_cpu
, dest_cpu
));
5632 * While a dead CPU has no uninterruptible tasks queued at this point,
5633 * it might still have a nonzero ->nr_uninterruptible counter, because
5634 * for performance reasons the counter is not stricly tracking tasks to
5635 * their home CPUs. So we just add the counter to another CPU's counter,
5636 * to keep the global sum constant after CPU-down:
5638 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5640 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5641 unsigned long flags
;
5643 local_irq_save(flags
);
5644 double_rq_lock(rq_src
, rq_dest
);
5645 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5646 rq_src
->nr_uninterruptible
= 0;
5647 double_rq_unlock(rq_src
, rq_dest
);
5648 local_irq_restore(flags
);
5651 /* Run through task list and migrate tasks from the dead cpu. */
5652 static void migrate_live_tasks(int src_cpu
)
5654 struct task_struct
*p
, *t
;
5656 read_lock(&tasklist_lock
);
5658 do_each_thread(t
, p
) {
5662 if (task_cpu(p
) == src_cpu
)
5663 move_task_off_dead_cpu(src_cpu
, p
);
5664 } while_each_thread(t
, p
);
5666 read_unlock(&tasklist_lock
);
5670 * Schedules idle task to be the next runnable task on current CPU.
5671 * It does so by boosting its priority to highest possible.
5672 * Used by CPU offline code.
5674 void sched_idle_next(void)
5676 int this_cpu
= smp_processor_id();
5677 struct rq
*rq
= cpu_rq(this_cpu
);
5678 struct task_struct
*p
= rq
->idle
;
5679 unsigned long flags
;
5681 /* cpu has to be offline */
5682 BUG_ON(cpu_online(this_cpu
));
5685 * Strictly not necessary since rest of the CPUs are stopped by now
5686 * and interrupts disabled on the current cpu.
5688 spin_lock_irqsave(&rq
->lock
, flags
);
5690 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5692 update_rq_clock(rq
);
5693 activate_task(rq
, p
, 0);
5695 spin_unlock_irqrestore(&rq
->lock
, flags
);
5699 * Ensures that the idle task is using init_mm right before its cpu goes
5702 void idle_task_exit(void)
5704 struct mm_struct
*mm
= current
->active_mm
;
5706 BUG_ON(cpu_online(smp_processor_id()));
5709 switch_mm(mm
, &init_mm
, current
);
5713 /* called under rq->lock with disabled interrupts */
5714 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5716 struct rq
*rq
= cpu_rq(dead_cpu
);
5718 /* Must be exiting, otherwise would be on tasklist. */
5719 BUG_ON(!p
->exit_state
);
5721 /* Cannot have done final schedule yet: would have vanished. */
5722 BUG_ON(p
->state
== TASK_DEAD
);
5727 * Drop lock around migration; if someone else moves it,
5728 * that's OK. No task can be added to this CPU, so iteration is
5731 spin_unlock_irq(&rq
->lock
);
5732 move_task_off_dead_cpu(dead_cpu
, p
);
5733 spin_lock_irq(&rq
->lock
);
5738 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5739 static void migrate_dead_tasks(unsigned int dead_cpu
)
5741 struct rq
*rq
= cpu_rq(dead_cpu
);
5742 struct task_struct
*next
;
5745 if (!rq
->nr_running
)
5747 update_rq_clock(rq
);
5748 next
= pick_next_task(rq
, rq
->curr
);
5751 migrate_dead(dead_cpu
, next
);
5755 #endif /* CONFIG_HOTPLUG_CPU */
5757 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5759 static struct ctl_table sd_ctl_dir
[] = {
5761 .procname
= "sched_domain",
5767 static struct ctl_table sd_ctl_root
[] = {
5769 .ctl_name
= CTL_KERN
,
5770 .procname
= "kernel",
5772 .child
= sd_ctl_dir
,
5777 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5779 struct ctl_table
*entry
=
5780 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5785 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5787 struct ctl_table
*entry
;
5790 * In the intermediate directories, both the child directory and
5791 * procname are dynamically allocated and could fail but the mode
5792 * will always be set. In the lowest directory the names are
5793 * static strings and all have proc handlers.
5795 for (entry
= *tablep
; entry
->mode
; entry
++) {
5797 sd_free_ctl_entry(&entry
->child
);
5798 if (entry
->proc_handler
== NULL
)
5799 kfree(entry
->procname
);
5807 set_table_entry(struct ctl_table
*entry
,
5808 const char *procname
, void *data
, int maxlen
,
5809 mode_t mode
, proc_handler
*proc_handler
)
5811 entry
->procname
= procname
;
5813 entry
->maxlen
= maxlen
;
5815 entry
->proc_handler
= proc_handler
;
5818 static struct ctl_table
*
5819 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5821 struct ctl_table
*table
= sd_alloc_ctl_entry(12);
5826 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5827 sizeof(long), 0644, proc_doulongvec_minmax
);
5828 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5829 sizeof(long), 0644, proc_doulongvec_minmax
);
5830 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5831 sizeof(int), 0644, proc_dointvec_minmax
);
5832 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5833 sizeof(int), 0644, proc_dointvec_minmax
);
5834 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5835 sizeof(int), 0644, proc_dointvec_minmax
);
5836 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5837 sizeof(int), 0644, proc_dointvec_minmax
);
5838 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5839 sizeof(int), 0644, proc_dointvec_minmax
);
5840 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5841 sizeof(int), 0644, proc_dointvec_minmax
);
5842 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5843 sizeof(int), 0644, proc_dointvec_minmax
);
5844 set_table_entry(&table
[9], "cache_nice_tries",
5845 &sd
->cache_nice_tries
,
5846 sizeof(int), 0644, proc_dointvec_minmax
);
5847 set_table_entry(&table
[10], "flags", &sd
->flags
,
5848 sizeof(int), 0644, proc_dointvec_minmax
);
5849 /* &table[11] is terminator */
5854 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5856 struct ctl_table
*entry
, *table
;
5857 struct sched_domain
*sd
;
5858 int domain_num
= 0, i
;
5861 for_each_domain(cpu
, sd
)
5863 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5868 for_each_domain(cpu
, sd
) {
5869 snprintf(buf
, 32, "domain%d", i
);
5870 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5872 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5879 static struct ctl_table_header
*sd_sysctl_header
;
5880 static void register_sched_domain_sysctl(void)
5882 int i
, cpu_num
= num_online_cpus();
5883 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5886 WARN_ON(sd_ctl_dir
[0].child
);
5887 sd_ctl_dir
[0].child
= entry
;
5892 for_each_online_cpu(i
) {
5893 snprintf(buf
, 32, "cpu%d", i
);
5894 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5896 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5900 WARN_ON(sd_sysctl_header
);
5901 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5904 /* may be called multiple times per register */
5905 static void unregister_sched_domain_sysctl(void)
5907 if (sd_sysctl_header
)
5908 unregister_sysctl_table(sd_sysctl_header
);
5909 sd_sysctl_header
= NULL
;
5910 if (sd_ctl_dir
[0].child
)
5911 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5914 static void register_sched_domain_sysctl(void)
5917 static void unregister_sched_domain_sysctl(void)
5923 * migration_call - callback that gets triggered when a CPU is added.
5924 * Here we can start up the necessary migration thread for the new CPU.
5926 static int __cpuinit
5927 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5929 struct task_struct
*p
;
5930 int cpu
= (long)hcpu
;
5931 unsigned long flags
;
5936 case CPU_UP_PREPARE
:
5937 case CPU_UP_PREPARE_FROZEN
:
5938 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5941 kthread_bind(p
, cpu
);
5942 /* Must be high prio: stop_machine expects to yield to it. */
5943 rq
= task_rq_lock(p
, &flags
);
5944 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5945 task_rq_unlock(rq
, &flags
);
5946 cpu_rq(cpu
)->migration_thread
= p
;
5950 case CPU_ONLINE_FROZEN
:
5951 /* Strictly unnecessary, as first user will wake it. */
5952 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5954 /* Update our root-domain */
5956 spin_lock_irqsave(&rq
->lock
, flags
);
5958 BUG_ON(!cpu_isset(cpu
, rq
->rd
->span
));
5959 cpu_set(cpu
, rq
->rd
->online
);
5961 spin_unlock_irqrestore(&rq
->lock
, flags
);
5964 #ifdef CONFIG_HOTPLUG_CPU
5965 case CPU_UP_CANCELED
:
5966 case CPU_UP_CANCELED_FROZEN
:
5967 if (!cpu_rq(cpu
)->migration_thread
)
5969 /* Unbind it from offline cpu so it can run. Fall thru. */
5970 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5971 any_online_cpu(cpu_online_map
));
5972 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5973 cpu_rq(cpu
)->migration_thread
= NULL
;
5977 case CPU_DEAD_FROZEN
:
5978 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
5979 migrate_live_tasks(cpu
);
5981 kthread_stop(rq
->migration_thread
);
5982 rq
->migration_thread
= NULL
;
5983 /* Idle task back to normal (off runqueue, low prio) */
5984 spin_lock_irq(&rq
->lock
);
5985 update_rq_clock(rq
);
5986 deactivate_task(rq
, rq
->idle
, 0);
5987 rq
->idle
->static_prio
= MAX_PRIO
;
5988 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5989 rq
->idle
->sched_class
= &idle_sched_class
;
5990 migrate_dead_tasks(cpu
);
5991 spin_unlock_irq(&rq
->lock
);
5993 migrate_nr_uninterruptible(rq
);
5994 BUG_ON(rq
->nr_running
!= 0);
5997 * No need to migrate the tasks: it was best-effort if
5998 * they didn't take sched_hotcpu_mutex. Just wake up
6001 spin_lock_irq(&rq
->lock
);
6002 while (!list_empty(&rq
->migration_queue
)) {
6003 struct migration_req
*req
;
6005 req
= list_entry(rq
->migration_queue
.next
,
6006 struct migration_req
, list
);
6007 list_del_init(&req
->list
);
6008 complete(&req
->done
);
6010 spin_unlock_irq(&rq
->lock
);
6014 case CPU_DYING_FROZEN
:
6015 /* Update our root-domain */
6017 spin_lock_irqsave(&rq
->lock
, flags
);
6019 BUG_ON(!cpu_isset(cpu
, rq
->rd
->span
));
6020 cpu_clear(cpu
, rq
->rd
->online
);
6022 spin_unlock_irqrestore(&rq
->lock
, flags
);
6029 /* Register at highest priority so that task migration (migrate_all_tasks)
6030 * happens before everything else.
6032 static struct notifier_block __cpuinitdata migration_notifier
= {
6033 .notifier_call
= migration_call
,
6037 void __init
migration_init(void)
6039 void *cpu
= (void *)(long)smp_processor_id();
6042 /* Start one for the boot CPU: */
6043 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
6044 BUG_ON(err
== NOTIFY_BAD
);
6045 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
6046 register_cpu_notifier(&migration_notifier
);
6052 /* Number of possible processor ids */
6053 int nr_cpu_ids __read_mostly
= NR_CPUS
;
6054 EXPORT_SYMBOL(nr_cpu_ids
);
6056 #ifdef CONFIG_SCHED_DEBUG
6058 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
)
6060 struct sched_group
*group
= sd
->groups
;
6061 cpumask_t groupmask
;
6064 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
6065 cpus_clear(groupmask
);
6067 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
6069 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
6070 printk("does not load-balance\n");
6072 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
6077 printk(KERN_CONT
"span %s\n", str
);
6079 if (!cpu_isset(cpu
, sd
->span
)) {
6080 printk(KERN_ERR
"ERROR: domain->span does not contain "
6083 if (!cpu_isset(cpu
, group
->cpumask
)) {
6084 printk(KERN_ERR
"ERROR: domain->groups does not contain"
6088 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
6092 printk(KERN_ERR
"ERROR: group is NULL\n");
6096 if (!group
->__cpu_power
) {
6097 printk(KERN_CONT
"\n");
6098 printk(KERN_ERR
"ERROR: domain->cpu_power not "
6103 if (!cpus_weight(group
->cpumask
)) {
6104 printk(KERN_CONT
"\n");
6105 printk(KERN_ERR
"ERROR: empty group\n");
6109 if (cpus_intersects(groupmask
, group
->cpumask
)) {
6110 printk(KERN_CONT
"\n");
6111 printk(KERN_ERR
"ERROR: repeated CPUs\n");
6115 cpus_or(groupmask
, groupmask
, group
->cpumask
);
6117 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
6118 printk(KERN_CONT
" %s", str
);
6120 group
= group
->next
;
6121 } while (group
!= sd
->groups
);
6122 printk(KERN_CONT
"\n");
6124 if (!cpus_equal(sd
->span
, groupmask
))
6125 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
6127 if (sd
->parent
&& !cpus_subset(groupmask
, sd
->parent
->span
))
6128 printk(KERN_ERR
"ERROR: parent span is not a superset "
6129 "of domain->span\n");
6133 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
6138 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
6142 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
6145 if (sched_domain_debug_one(sd
, cpu
, level
))
6154 # define sched_domain_debug(sd, cpu) do { } while (0)
6157 static int sd_degenerate(struct sched_domain
*sd
)
6159 if (cpus_weight(sd
->span
) == 1)
6162 /* Following flags need at least 2 groups */
6163 if (sd
->flags
& (SD_LOAD_BALANCE
|
6164 SD_BALANCE_NEWIDLE
|
6168 SD_SHARE_PKG_RESOURCES
)) {
6169 if (sd
->groups
!= sd
->groups
->next
)
6173 /* Following flags don't use groups */
6174 if (sd
->flags
& (SD_WAKE_IDLE
|
6183 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
6185 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
6187 if (sd_degenerate(parent
))
6190 if (!cpus_equal(sd
->span
, parent
->span
))
6193 /* Does parent contain flags not in child? */
6194 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
6195 if (cflags
& SD_WAKE_AFFINE
)
6196 pflags
&= ~SD_WAKE_BALANCE
;
6197 /* Flags needing groups don't count if only 1 group in parent */
6198 if (parent
->groups
== parent
->groups
->next
) {
6199 pflags
&= ~(SD_LOAD_BALANCE
|
6200 SD_BALANCE_NEWIDLE
|
6204 SD_SHARE_PKG_RESOURCES
);
6206 if (~cflags
& pflags
)
6212 static void rq_attach_root(struct rq
*rq
, struct root_domain
*rd
)
6214 unsigned long flags
;
6215 const struct sched_class
*class;
6217 spin_lock_irqsave(&rq
->lock
, flags
);
6220 struct root_domain
*old_rd
= rq
->rd
;
6222 for (class = sched_class_highest
; class; class = class->next
) {
6223 if (class->leave_domain
)
6224 class->leave_domain(rq
);
6227 cpu_clear(rq
->cpu
, old_rd
->span
);
6228 cpu_clear(rq
->cpu
, old_rd
->online
);
6230 if (atomic_dec_and_test(&old_rd
->refcount
))
6234 atomic_inc(&rd
->refcount
);
6237 cpu_set(rq
->cpu
, rd
->span
);
6238 if (cpu_isset(rq
->cpu
, cpu_online_map
))
6239 cpu_set(rq
->cpu
, rd
->online
);
6241 for (class = sched_class_highest
; class; class = class->next
) {
6242 if (class->join_domain
)
6243 class->join_domain(rq
);
6246 spin_unlock_irqrestore(&rq
->lock
, flags
);
6249 static void init_rootdomain(struct root_domain
*rd
)
6251 memset(rd
, 0, sizeof(*rd
));
6253 cpus_clear(rd
->span
);
6254 cpus_clear(rd
->online
);
6257 static void init_defrootdomain(void)
6259 init_rootdomain(&def_root_domain
);
6260 atomic_set(&def_root_domain
.refcount
, 1);
6263 static struct root_domain
*alloc_rootdomain(void)
6265 struct root_domain
*rd
;
6267 rd
= kmalloc(sizeof(*rd
), GFP_KERNEL
);
6271 init_rootdomain(rd
);
6277 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
6278 * hold the hotplug lock.
6281 cpu_attach_domain(struct sched_domain
*sd
, struct root_domain
*rd
, int cpu
)
6283 struct rq
*rq
= cpu_rq(cpu
);
6284 struct sched_domain
*tmp
;
6286 /* Remove the sched domains which do not contribute to scheduling. */
6287 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
6288 struct sched_domain
*parent
= tmp
->parent
;
6291 if (sd_parent_degenerate(tmp
, parent
)) {
6292 tmp
->parent
= parent
->parent
;
6294 parent
->parent
->child
= tmp
;
6298 if (sd
&& sd_degenerate(sd
)) {
6304 sched_domain_debug(sd
, cpu
);
6306 rq_attach_root(rq
, rd
);
6307 rcu_assign_pointer(rq
->sd
, sd
);
6310 /* cpus with isolated domains */
6311 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
6313 /* Setup the mask of cpus configured for isolated domains */
6314 static int __init
isolated_cpu_setup(char *str
)
6316 int ints
[NR_CPUS
], i
;
6318 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
6319 cpus_clear(cpu_isolated_map
);
6320 for (i
= 1; i
<= ints
[0]; i
++)
6321 if (ints
[i
] < NR_CPUS
)
6322 cpu_set(ints
[i
], cpu_isolated_map
);
6326 __setup("isolcpus=", isolated_cpu_setup
);
6329 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
6330 * to a function which identifies what group(along with sched group) a CPU
6331 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
6332 * (due to the fact that we keep track of groups covered with a cpumask_t).
6334 * init_sched_build_groups will build a circular linked list of the groups
6335 * covered by the given span, and will set each group's ->cpumask correctly,
6336 * and ->cpu_power to 0.
6339 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
6340 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
6341 struct sched_group
**sg
))
6343 struct sched_group
*first
= NULL
, *last
= NULL
;
6344 cpumask_t covered
= CPU_MASK_NONE
;
6347 for_each_cpu_mask(i
, span
) {
6348 struct sched_group
*sg
;
6349 int group
= group_fn(i
, cpu_map
, &sg
);
6352 if (cpu_isset(i
, covered
))
6355 sg
->cpumask
= CPU_MASK_NONE
;
6356 sg
->__cpu_power
= 0;
6358 for_each_cpu_mask(j
, span
) {
6359 if (group_fn(j
, cpu_map
, NULL
) != group
)
6362 cpu_set(j
, covered
);
6363 cpu_set(j
, sg
->cpumask
);
6374 #define SD_NODES_PER_DOMAIN 16
6379 * find_next_best_node - find the next node to include in a sched_domain
6380 * @node: node whose sched_domain we're building
6381 * @used_nodes: nodes already in the sched_domain
6383 * Find the next node to include in a given scheduling domain. Simply
6384 * finds the closest node not already in the @used_nodes map.
6386 * Should use nodemask_t.
6388 static int find_next_best_node(int node
, unsigned long *used_nodes
)
6390 int i
, n
, val
, min_val
, best_node
= 0;
6394 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6395 /* Start at @node */
6396 n
= (node
+ i
) % MAX_NUMNODES
;
6398 if (!nr_cpus_node(n
))
6401 /* Skip already used nodes */
6402 if (test_bit(n
, used_nodes
))
6405 /* Simple min distance search */
6406 val
= node_distance(node
, n
);
6408 if (val
< min_val
) {
6414 set_bit(best_node
, used_nodes
);
6419 * sched_domain_node_span - get a cpumask for a node's sched_domain
6420 * @node: node whose cpumask we're constructing
6421 * @size: number of nodes to include in this span
6423 * Given a node, construct a good cpumask for its sched_domain to span. It
6424 * should be one that prevents unnecessary balancing, but also spreads tasks
6427 static cpumask_t
sched_domain_node_span(int node
)
6429 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
6430 cpumask_t span
, nodemask
;
6434 bitmap_zero(used_nodes
, MAX_NUMNODES
);
6436 nodemask
= node_to_cpumask(node
);
6437 cpus_or(span
, span
, nodemask
);
6438 set_bit(node
, used_nodes
);
6440 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6441 int next_node
= find_next_best_node(node
, used_nodes
);
6443 nodemask
= node_to_cpumask(next_node
);
6444 cpus_or(span
, span
, nodemask
);
6451 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
6454 * SMT sched-domains:
6456 #ifdef CONFIG_SCHED_SMT
6457 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
6458 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6461 cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6464 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6470 * multi-core sched-domains:
6472 #ifdef CONFIG_SCHED_MC
6473 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6474 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6477 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6479 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6482 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6483 cpus_and(mask
, mask
, *cpu_map
);
6484 group
= first_cpu(mask
);
6486 *sg
= &per_cpu(sched_group_core
, group
);
6489 #elif defined(CONFIG_SCHED_MC)
6491 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6494 *sg
= &per_cpu(sched_group_core
, cpu
);
6499 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6500 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6503 cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6506 #ifdef CONFIG_SCHED_MC
6507 cpumask_t mask
= cpu_coregroup_map(cpu
);
6508 cpus_and(mask
, mask
, *cpu_map
);
6509 group
= first_cpu(mask
);
6510 #elif defined(CONFIG_SCHED_SMT)
6511 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6512 cpus_and(mask
, mask
, *cpu_map
);
6513 group
= first_cpu(mask
);
6518 *sg
= &per_cpu(sched_group_phys
, group
);
6524 * The init_sched_build_groups can't handle what we want to do with node
6525 * groups, so roll our own. Now each node has its own list of groups which
6526 * gets dynamically allocated.
6528 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6529 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6531 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6532 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6534 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6535 struct sched_group
**sg
)
6537 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6540 cpus_and(nodemask
, nodemask
, *cpu_map
);
6541 group
= first_cpu(nodemask
);
6544 *sg
= &per_cpu(sched_group_allnodes
, group
);
6548 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6550 struct sched_group
*sg
= group_head
;
6556 for_each_cpu_mask(j
, sg
->cpumask
) {
6557 struct sched_domain
*sd
;
6559 sd
= &per_cpu(phys_domains
, j
);
6560 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6562 * Only add "power" once for each
6568 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
6571 } while (sg
!= group_head
);
6576 /* Free memory allocated for various sched_group structures */
6577 static void free_sched_groups(const cpumask_t
*cpu_map
)
6581 for_each_cpu_mask(cpu
, *cpu_map
) {
6582 struct sched_group
**sched_group_nodes
6583 = sched_group_nodes_bycpu
[cpu
];
6585 if (!sched_group_nodes
)
6588 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6589 cpumask_t nodemask
= node_to_cpumask(i
);
6590 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6592 cpus_and(nodemask
, nodemask
, *cpu_map
);
6593 if (cpus_empty(nodemask
))
6603 if (oldsg
!= sched_group_nodes
[i
])
6606 kfree(sched_group_nodes
);
6607 sched_group_nodes_bycpu
[cpu
] = NULL
;
6611 static void free_sched_groups(const cpumask_t
*cpu_map
)
6617 * Initialize sched groups cpu_power.
6619 * cpu_power indicates the capacity of sched group, which is used while
6620 * distributing the load between different sched groups in a sched domain.
6621 * Typically cpu_power for all the groups in a sched domain will be same unless
6622 * there are asymmetries in the topology. If there are asymmetries, group
6623 * having more cpu_power will pickup more load compared to the group having
6626 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6627 * the maximum number of tasks a group can handle in the presence of other idle
6628 * or lightly loaded groups in the same sched domain.
6630 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6632 struct sched_domain
*child
;
6633 struct sched_group
*group
;
6635 WARN_ON(!sd
|| !sd
->groups
);
6637 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6642 sd
->groups
->__cpu_power
= 0;
6645 * For perf policy, if the groups in child domain share resources
6646 * (for example cores sharing some portions of the cache hierarchy
6647 * or SMT), then set this domain groups cpu_power such that each group
6648 * can handle only one task, when there are other idle groups in the
6649 * same sched domain.
6651 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6653 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6654 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
6659 * add cpu_power of each child group to this groups cpu_power
6661 group
= child
->groups
;
6663 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
6664 group
= group
->next
;
6665 } while (group
!= child
->groups
);
6669 * Build sched domains for a given set of cpus and attach the sched domains
6670 * to the individual cpus
6672 static int build_sched_domains(const cpumask_t
*cpu_map
)
6675 struct root_domain
*rd
;
6677 struct sched_group
**sched_group_nodes
= NULL
;
6678 int sd_allnodes
= 0;
6681 * Allocate the per-node list of sched groups
6683 sched_group_nodes
= kcalloc(MAX_NUMNODES
, sizeof(struct sched_group
*),
6685 if (!sched_group_nodes
) {
6686 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6689 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6692 rd
= alloc_rootdomain();
6694 printk(KERN_WARNING
"Cannot alloc root domain\n");
6699 * Set up domains for cpus specified by the cpu_map.
6701 for_each_cpu_mask(i
, *cpu_map
) {
6702 struct sched_domain
*sd
= NULL
, *p
;
6703 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6705 cpus_and(nodemask
, nodemask
, *cpu_map
);
6708 if (cpus_weight(*cpu_map
) >
6709 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6710 sd
= &per_cpu(allnodes_domains
, i
);
6711 *sd
= SD_ALLNODES_INIT
;
6712 sd
->span
= *cpu_map
;
6713 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6719 sd
= &per_cpu(node_domains
, i
);
6721 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6725 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6729 sd
= &per_cpu(phys_domains
, i
);
6731 sd
->span
= nodemask
;
6735 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6737 #ifdef CONFIG_SCHED_MC
6739 sd
= &per_cpu(core_domains
, i
);
6741 sd
->span
= cpu_coregroup_map(i
);
6742 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6745 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6748 #ifdef CONFIG_SCHED_SMT
6750 sd
= &per_cpu(cpu_domains
, i
);
6751 *sd
= SD_SIBLING_INIT
;
6752 sd
->span
= per_cpu(cpu_sibling_map
, i
);
6753 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6756 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6760 #ifdef CONFIG_SCHED_SMT
6761 /* Set up CPU (sibling) groups */
6762 for_each_cpu_mask(i
, *cpu_map
) {
6763 cpumask_t this_sibling_map
= per_cpu(cpu_sibling_map
, i
);
6764 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6765 if (i
!= first_cpu(this_sibling_map
))
6768 init_sched_build_groups(this_sibling_map
, cpu_map
,
6773 #ifdef CONFIG_SCHED_MC
6774 /* Set up multi-core groups */
6775 for_each_cpu_mask(i
, *cpu_map
) {
6776 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6777 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6778 if (i
!= first_cpu(this_core_map
))
6780 init_sched_build_groups(this_core_map
, cpu_map
,
6781 &cpu_to_core_group
);
6785 /* Set up physical groups */
6786 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6787 cpumask_t nodemask
= node_to_cpumask(i
);
6789 cpus_and(nodemask
, nodemask
, *cpu_map
);
6790 if (cpus_empty(nodemask
))
6793 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6797 /* Set up node groups */
6799 init_sched_build_groups(*cpu_map
, cpu_map
,
6800 &cpu_to_allnodes_group
);
6802 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6803 /* Set up node groups */
6804 struct sched_group
*sg
, *prev
;
6805 cpumask_t nodemask
= node_to_cpumask(i
);
6806 cpumask_t domainspan
;
6807 cpumask_t covered
= CPU_MASK_NONE
;
6810 cpus_and(nodemask
, nodemask
, *cpu_map
);
6811 if (cpus_empty(nodemask
)) {
6812 sched_group_nodes
[i
] = NULL
;
6816 domainspan
= sched_domain_node_span(i
);
6817 cpus_and(domainspan
, domainspan
, *cpu_map
);
6819 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6821 printk(KERN_WARNING
"Can not alloc domain group for "
6825 sched_group_nodes
[i
] = sg
;
6826 for_each_cpu_mask(j
, nodemask
) {
6827 struct sched_domain
*sd
;
6829 sd
= &per_cpu(node_domains
, j
);
6832 sg
->__cpu_power
= 0;
6833 sg
->cpumask
= nodemask
;
6835 cpus_or(covered
, covered
, nodemask
);
6838 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6839 cpumask_t tmp
, notcovered
;
6840 int n
= (i
+ j
) % MAX_NUMNODES
;
6842 cpus_complement(notcovered
, covered
);
6843 cpus_and(tmp
, notcovered
, *cpu_map
);
6844 cpus_and(tmp
, tmp
, domainspan
);
6845 if (cpus_empty(tmp
))
6848 nodemask
= node_to_cpumask(n
);
6849 cpus_and(tmp
, tmp
, nodemask
);
6850 if (cpus_empty(tmp
))
6853 sg
= kmalloc_node(sizeof(struct sched_group
),
6857 "Can not alloc domain group for node %d\n", j
);
6860 sg
->__cpu_power
= 0;
6862 sg
->next
= prev
->next
;
6863 cpus_or(covered
, covered
, tmp
);
6870 /* Calculate CPU power for physical packages and nodes */
6871 #ifdef CONFIG_SCHED_SMT
6872 for_each_cpu_mask(i
, *cpu_map
) {
6873 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6875 init_sched_groups_power(i
, sd
);
6878 #ifdef CONFIG_SCHED_MC
6879 for_each_cpu_mask(i
, *cpu_map
) {
6880 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6882 init_sched_groups_power(i
, sd
);
6886 for_each_cpu_mask(i
, *cpu_map
) {
6887 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6889 init_sched_groups_power(i
, sd
);
6893 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6894 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6897 struct sched_group
*sg
;
6899 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6900 init_numa_sched_groups_power(sg
);
6904 /* Attach the domains */
6905 for_each_cpu_mask(i
, *cpu_map
) {
6906 struct sched_domain
*sd
;
6907 #ifdef CONFIG_SCHED_SMT
6908 sd
= &per_cpu(cpu_domains
, i
);
6909 #elif defined(CONFIG_SCHED_MC)
6910 sd
= &per_cpu(core_domains
, i
);
6912 sd
= &per_cpu(phys_domains
, i
);
6914 cpu_attach_domain(sd
, rd
, i
);
6921 free_sched_groups(cpu_map
);
6926 static cpumask_t
*doms_cur
; /* current sched domains */
6927 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6930 * Special case: If a kmalloc of a doms_cur partition (array of
6931 * cpumask_t) fails, then fallback to a single sched domain,
6932 * as determined by the single cpumask_t fallback_doms.
6934 static cpumask_t fallback_doms
;
6936 void __attribute__((weak
)) arch_update_cpu_topology(void)
6941 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6942 * For now this just excludes isolated cpus, but could be used to
6943 * exclude other special cases in the future.
6945 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6949 arch_update_cpu_topology();
6951 doms_cur
= kmalloc(sizeof(cpumask_t
), GFP_KERNEL
);
6953 doms_cur
= &fallback_doms
;
6954 cpus_andnot(*doms_cur
, *cpu_map
, cpu_isolated_map
);
6955 err
= build_sched_domains(doms_cur
);
6956 register_sched_domain_sysctl();
6961 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6963 free_sched_groups(cpu_map
);
6967 * Detach sched domains from a group of cpus specified in cpu_map
6968 * These cpus will now be attached to the NULL domain
6970 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6974 unregister_sched_domain_sysctl();
6976 for_each_cpu_mask(i
, *cpu_map
)
6977 cpu_attach_domain(NULL
, &def_root_domain
, i
);
6978 synchronize_sched();
6979 arch_destroy_sched_domains(cpu_map
);
6983 * Partition sched domains as specified by the 'ndoms_new'
6984 * cpumasks in the array doms_new[] of cpumasks. This compares
6985 * doms_new[] to the current sched domain partitioning, doms_cur[].
6986 * It destroys each deleted domain and builds each new domain.
6988 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
6989 * The masks don't intersect (don't overlap.) We should setup one
6990 * sched domain for each mask. CPUs not in any of the cpumasks will
6991 * not be load balanced. If the same cpumask appears both in the
6992 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6995 * The passed in 'doms_new' should be kmalloc'd. This routine takes
6996 * ownership of it and will kfree it when done with it. If the caller
6997 * failed the kmalloc call, then it can pass in doms_new == NULL,
6998 * and partition_sched_domains() will fallback to the single partition
7001 * Call with hotplug lock held
7003 void partition_sched_domains(int ndoms_new
, cpumask_t
*doms_new
)
7009 /* always unregister in case we don't destroy any domains */
7010 unregister_sched_domain_sysctl();
7012 if (doms_new
== NULL
) {
7014 doms_new
= &fallback_doms
;
7015 cpus_andnot(doms_new
[0], cpu_online_map
, cpu_isolated_map
);
7018 /* Destroy deleted domains */
7019 for (i
= 0; i
< ndoms_cur
; i
++) {
7020 for (j
= 0; j
< ndoms_new
; j
++) {
7021 if (cpus_equal(doms_cur
[i
], doms_new
[j
]))
7024 /* no match - a current sched domain not in new doms_new[] */
7025 detach_destroy_domains(doms_cur
+ i
);
7030 /* Build new domains */
7031 for (i
= 0; i
< ndoms_new
; i
++) {
7032 for (j
= 0; j
< ndoms_cur
; j
++) {
7033 if (cpus_equal(doms_new
[i
], doms_cur
[j
]))
7036 /* no match - add a new doms_new */
7037 build_sched_domains(doms_new
+ i
);
7042 /* Remember the new sched domains */
7043 if (doms_cur
!= &fallback_doms
)
7045 doms_cur
= doms_new
;
7046 ndoms_cur
= ndoms_new
;
7048 register_sched_domain_sysctl();
7053 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
7054 int arch_reinit_sched_domains(void)
7059 detach_destroy_domains(&cpu_online_map
);
7060 err
= arch_init_sched_domains(&cpu_online_map
);
7066 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
7070 if (buf
[0] != '0' && buf
[0] != '1')
7074 sched_smt_power_savings
= (buf
[0] == '1');
7076 sched_mc_power_savings
= (buf
[0] == '1');
7078 ret
= arch_reinit_sched_domains();
7080 return ret
? ret
: count
;
7083 #ifdef CONFIG_SCHED_MC
7084 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
7086 return sprintf(page
, "%u\n", sched_mc_power_savings
);
7088 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
7089 const char *buf
, size_t count
)
7091 return sched_power_savings_store(buf
, count
, 0);
7093 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
7094 sched_mc_power_savings_store
);
7097 #ifdef CONFIG_SCHED_SMT
7098 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
7100 return sprintf(page
, "%u\n", sched_smt_power_savings
);
7102 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
7103 const char *buf
, size_t count
)
7105 return sched_power_savings_store(buf
, count
, 1);
7107 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
7108 sched_smt_power_savings_store
);
7111 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
7115 #ifdef CONFIG_SCHED_SMT
7117 err
= sysfs_create_file(&cls
->kset
.kobj
,
7118 &attr_sched_smt_power_savings
.attr
);
7120 #ifdef CONFIG_SCHED_MC
7121 if (!err
&& mc_capable())
7122 err
= sysfs_create_file(&cls
->kset
.kobj
,
7123 &attr_sched_mc_power_savings
.attr
);
7130 * Force a reinitialization of the sched domains hierarchy. The domains
7131 * and groups cannot be updated in place without racing with the balancing
7132 * code, so we temporarily attach all running cpus to the NULL domain
7133 * which will prevent rebalancing while the sched domains are recalculated.
7135 static int update_sched_domains(struct notifier_block
*nfb
,
7136 unsigned long action
, void *hcpu
)
7139 case CPU_UP_PREPARE
:
7140 case CPU_UP_PREPARE_FROZEN
:
7141 case CPU_DOWN_PREPARE
:
7142 case CPU_DOWN_PREPARE_FROZEN
:
7143 detach_destroy_domains(&cpu_online_map
);
7146 case CPU_UP_CANCELED
:
7147 case CPU_UP_CANCELED_FROZEN
:
7148 case CPU_DOWN_FAILED
:
7149 case CPU_DOWN_FAILED_FROZEN
:
7151 case CPU_ONLINE_FROZEN
:
7153 case CPU_DEAD_FROZEN
:
7155 * Fall through and re-initialise the domains.
7162 /* The hotplug lock is already held by cpu_up/cpu_down */
7163 arch_init_sched_domains(&cpu_online_map
);
7168 void __init
sched_init_smp(void)
7170 cpumask_t non_isolated_cpus
;
7173 arch_init_sched_domains(&cpu_online_map
);
7174 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
7175 if (cpus_empty(non_isolated_cpus
))
7176 cpu_set(smp_processor_id(), non_isolated_cpus
);
7178 /* XXX: Theoretical race here - CPU may be hotplugged now */
7179 hotcpu_notifier(update_sched_domains
, 0);
7181 /* Move init over to a non-isolated CPU */
7182 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
7184 sched_init_granularity();
7187 void __init
sched_init_smp(void)
7189 sched_init_granularity();
7191 #endif /* CONFIG_SMP */
7193 int in_sched_functions(unsigned long addr
)
7195 return in_lock_functions(addr
) ||
7196 (addr
>= (unsigned long)__sched_text_start
7197 && addr
< (unsigned long)__sched_text_end
);
7200 static void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
7202 cfs_rq
->tasks_timeline
= RB_ROOT
;
7203 #ifdef CONFIG_FAIR_GROUP_SCHED
7206 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
7209 static void init_rt_rq(struct rt_rq
*rt_rq
, struct rq
*rq
)
7211 struct rt_prio_array
*array
;
7214 array
= &rt_rq
->active
;
7215 for (i
= 0; i
< MAX_RT_PRIO
; i
++) {
7216 INIT_LIST_HEAD(array
->queue
+ i
);
7217 __clear_bit(i
, array
->bitmap
);
7219 /* delimiter for bitsearch: */
7220 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
7222 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
7223 rt_rq
->highest_prio
= MAX_RT_PRIO
;
7226 rt_rq
->rt_nr_migratory
= 0;
7227 rt_rq
->overloaded
= 0;
7231 rt_rq
->rt_throttled
= 0;
7233 #ifdef CONFIG_RT_GROUP_SCHED
7234 rt_rq
->rt_nr_boosted
= 0;
7239 #ifdef CONFIG_FAIR_GROUP_SCHED
7240 static void init_tg_cfs_entry(struct rq
*rq
, struct task_group
*tg
,
7241 struct cfs_rq
*cfs_rq
, struct sched_entity
*se
,
7244 tg
->cfs_rq
[cpu
] = cfs_rq
;
7245 init_cfs_rq(cfs_rq
, rq
);
7248 list_add(&cfs_rq
->leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
7251 se
->cfs_rq
= &rq
->cfs
;
7253 se
->load
.weight
= tg
->shares
;
7254 se
->load
.inv_weight
= div64_64(1ULL<<32, se
->load
.weight
);
7259 #ifdef CONFIG_RT_GROUP_SCHED
7260 static void init_tg_rt_entry(struct rq
*rq
, struct task_group
*tg
,
7261 struct rt_rq
*rt_rq
, struct sched_rt_entity
*rt_se
,
7264 tg
->rt_rq
[cpu
] = rt_rq
;
7265 init_rt_rq(rt_rq
, rq
);
7267 rt_rq
->rt_se
= rt_se
;
7269 list_add(&rt_rq
->leaf_rt_rq_list
, &rq
->leaf_rt_rq_list
);
7271 tg
->rt_se
[cpu
] = rt_se
;
7272 rt_se
->rt_rq
= &rq
->rt
;
7273 rt_se
->my_q
= rt_rq
;
7274 rt_se
->parent
= NULL
;
7275 INIT_LIST_HEAD(&rt_se
->run_list
);
7279 void __init
sched_init(void)
7281 int highest_cpu
= 0;
7285 init_defrootdomain();
7288 #ifdef CONFIG_GROUP_SCHED
7289 list_add(&init_task_group
.list
, &task_groups
);
7292 for_each_possible_cpu(i
) {
7296 spin_lock_init(&rq
->lock
);
7297 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
7300 update_last_tick_seen(rq
);
7301 init_cfs_rq(&rq
->cfs
, rq
);
7302 init_rt_rq(&rq
->rt
, rq
);
7303 #ifdef CONFIG_FAIR_GROUP_SCHED
7304 init_task_group
.shares
= init_task_group_load
;
7305 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
7306 init_tg_cfs_entry(rq
, &init_task_group
,
7307 &per_cpu(init_cfs_rq
, i
),
7308 &per_cpu(init_sched_entity
, i
), i
, 1);
7311 #ifdef CONFIG_RT_GROUP_SCHED
7312 init_task_group
.rt_runtime
=
7313 sysctl_sched_rt_runtime
* NSEC_PER_USEC
;
7314 INIT_LIST_HEAD(&rq
->leaf_rt_rq_list
);
7315 init_tg_rt_entry(rq
, &init_task_group
,
7316 &per_cpu(init_rt_rq
, i
),
7317 &per_cpu(init_sched_rt_entity
, i
), i
, 1);
7319 rq
->rt_period_expire
= 0;
7320 rq
->rt_throttled
= 0;
7322 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
7323 rq
->cpu_load
[j
] = 0;
7327 rq
->active_balance
= 0;
7328 rq
->next_balance
= jiffies
;
7331 rq
->migration_thread
= NULL
;
7332 INIT_LIST_HEAD(&rq
->migration_queue
);
7333 rq_attach_root(rq
, &def_root_domain
);
7336 atomic_set(&rq
->nr_iowait
, 0);
7340 set_load_weight(&init_task
);
7342 #ifdef CONFIG_PREEMPT_NOTIFIERS
7343 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
7347 nr_cpu_ids
= highest_cpu
+ 1;
7348 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
7351 #ifdef CONFIG_RT_MUTEXES
7352 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
7356 * The boot idle thread does lazy MMU switching as well:
7358 atomic_inc(&init_mm
.mm_count
);
7359 enter_lazy_tlb(&init_mm
, current
);
7362 * Make us the idle thread. Technically, schedule() should not be
7363 * called from this thread, however somewhere below it might be,
7364 * but because we are the idle thread, we just pick up running again
7365 * when this runqueue becomes "idle".
7367 init_idle(current
, smp_processor_id());
7369 * During early bootup we pretend to be a normal task:
7371 current
->sched_class
= &fair_sched_class
;
7373 scheduler_running
= 1;
7376 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
7377 void __might_sleep(char *file
, int line
)
7380 static unsigned long prev_jiffy
; /* ratelimiting */
7382 if ((in_atomic() || irqs_disabled()) &&
7383 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
7384 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
7386 prev_jiffy
= jiffies
;
7387 printk(KERN_ERR
"BUG: sleeping function called from invalid"
7388 " context at %s:%d\n", file
, line
);
7389 printk("in_atomic():%d, irqs_disabled():%d\n",
7390 in_atomic(), irqs_disabled());
7391 debug_show_held_locks(current
);
7392 if (irqs_disabled())
7393 print_irqtrace_events(current
);
7398 EXPORT_SYMBOL(__might_sleep
);
7401 #ifdef CONFIG_MAGIC_SYSRQ
7402 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
7405 update_rq_clock(rq
);
7406 on_rq
= p
->se
.on_rq
;
7408 deactivate_task(rq
, p
, 0);
7409 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
7411 activate_task(rq
, p
, 0);
7412 resched_task(rq
->curr
);
7416 void normalize_rt_tasks(void)
7418 struct task_struct
*g
, *p
;
7419 unsigned long flags
;
7422 read_lock_irqsave(&tasklist_lock
, flags
);
7423 do_each_thread(g
, p
) {
7425 * Only normalize user tasks:
7430 p
->se
.exec_start
= 0;
7431 #ifdef CONFIG_SCHEDSTATS
7432 p
->se
.wait_start
= 0;
7433 p
->se
.sleep_start
= 0;
7434 p
->se
.block_start
= 0;
7436 task_rq(p
)->clock
= 0;
7440 * Renice negative nice level userspace
7443 if (TASK_NICE(p
) < 0 && p
->mm
)
7444 set_user_nice(p
, 0);
7448 spin_lock(&p
->pi_lock
);
7449 rq
= __task_rq_lock(p
);
7451 normalize_task(rq
, p
);
7453 __task_rq_unlock(rq
);
7454 spin_unlock(&p
->pi_lock
);
7455 } while_each_thread(g
, p
);
7457 read_unlock_irqrestore(&tasklist_lock
, flags
);
7460 #endif /* CONFIG_MAGIC_SYSRQ */
7464 * These functions are only useful for the IA64 MCA handling.
7466 * They can only be called when the whole system has been
7467 * stopped - every CPU needs to be quiescent, and no scheduling
7468 * activity can take place. Using them for anything else would
7469 * be a serious bug, and as a result, they aren't even visible
7470 * under any other configuration.
7474 * curr_task - return the current task for a given cpu.
7475 * @cpu: the processor in question.
7477 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7479 struct task_struct
*curr_task(int cpu
)
7481 return cpu_curr(cpu
);
7485 * set_curr_task - set the current task for a given cpu.
7486 * @cpu: the processor in question.
7487 * @p: the task pointer to set.
7489 * Description: This function must only be used when non-maskable interrupts
7490 * are serviced on a separate stack. It allows the architecture to switch the
7491 * notion of the current task on a cpu in a non-blocking manner. This function
7492 * must be called with all CPU's synchronized, and interrupts disabled, the
7493 * and caller must save the original value of the current task (see
7494 * curr_task() above) and restore that value before reenabling interrupts and
7495 * re-starting the system.
7497 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7499 void set_curr_task(int cpu
, struct task_struct
*p
)
7506 #ifdef CONFIG_GROUP_SCHED
7508 #ifdef CONFIG_FAIR_GROUP_SCHED
7509 static void free_fair_sched_group(struct task_group
*tg
)
7513 for_each_possible_cpu(i
) {
7515 kfree(tg
->cfs_rq
[i
]);
7524 static int alloc_fair_sched_group(struct task_group
*tg
)
7526 struct cfs_rq
*cfs_rq
;
7527 struct sched_entity
*se
;
7531 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * NR_CPUS
, GFP_KERNEL
);
7534 tg
->se
= kzalloc(sizeof(se
) * NR_CPUS
, GFP_KERNEL
);
7538 tg
->shares
= NICE_0_LOAD
;
7540 for_each_possible_cpu(i
) {
7543 cfs_rq
= kmalloc_node(sizeof(struct cfs_rq
),
7544 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7548 se
= kmalloc_node(sizeof(struct sched_entity
),
7549 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7553 init_tg_cfs_entry(rq
, tg
, cfs_rq
, se
, i
, 0);
7562 static inline void register_fair_sched_group(struct task_group
*tg
, int cpu
)
7564 list_add_rcu(&tg
->cfs_rq
[cpu
]->leaf_cfs_rq_list
,
7565 &cpu_rq(cpu
)->leaf_cfs_rq_list
);
7568 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
7570 list_del_rcu(&tg
->cfs_rq
[cpu
]->leaf_cfs_rq_list
);
7573 static inline void free_fair_sched_group(struct task_group
*tg
)
7577 static inline int alloc_fair_sched_group(struct task_group
*tg
)
7582 static inline void register_fair_sched_group(struct task_group
*tg
, int cpu
)
7586 static inline void unregister_fair_sched_group(struct task_group
*tg
, int cpu
)
7591 #ifdef CONFIG_RT_GROUP_SCHED
7592 static void free_rt_sched_group(struct task_group
*tg
)
7596 for_each_possible_cpu(i
) {
7598 kfree(tg
->rt_rq
[i
]);
7600 kfree(tg
->rt_se
[i
]);
7607 static int alloc_rt_sched_group(struct task_group
*tg
)
7609 struct rt_rq
*rt_rq
;
7610 struct sched_rt_entity
*rt_se
;
7614 tg
->rt_rq
= kzalloc(sizeof(rt_rq
) * NR_CPUS
, GFP_KERNEL
);
7617 tg
->rt_se
= kzalloc(sizeof(rt_se
) * NR_CPUS
, GFP_KERNEL
);
7623 for_each_possible_cpu(i
) {
7626 rt_rq
= kmalloc_node(sizeof(struct rt_rq
),
7627 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7631 rt_se
= kmalloc_node(sizeof(struct sched_rt_entity
),
7632 GFP_KERNEL
|__GFP_ZERO
, cpu_to_node(i
));
7636 init_tg_rt_entry(rq
, tg
, rt_rq
, rt_se
, i
, 0);
7645 static inline void register_rt_sched_group(struct task_group
*tg
, int cpu
)
7647 list_add_rcu(&tg
->rt_rq
[cpu
]->leaf_rt_rq_list
,
7648 &cpu_rq(cpu
)->leaf_rt_rq_list
);
7651 static inline void unregister_rt_sched_group(struct task_group
*tg
, int cpu
)
7653 list_del_rcu(&tg
->rt_rq
[cpu
]->leaf_rt_rq_list
);
7656 static inline void free_rt_sched_group(struct task_group
*tg
)
7660 static inline int alloc_rt_sched_group(struct task_group
*tg
)
7665 static inline void register_rt_sched_group(struct task_group
*tg
, int cpu
)
7669 static inline void unregister_rt_sched_group(struct task_group
*tg
, int cpu
)
7674 static void free_sched_group(struct task_group
*tg
)
7676 free_fair_sched_group(tg
);
7677 free_rt_sched_group(tg
);
7681 /* allocate runqueue etc for a new task group */
7682 struct task_group
*sched_create_group(void)
7684 struct task_group
*tg
;
7685 unsigned long flags
;
7688 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7690 return ERR_PTR(-ENOMEM
);
7692 if (!alloc_fair_sched_group(tg
))
7695 if (!alloc_rt_sched_group(tg
))
7698 spin_lock_irqsave(&task_group_lock
, flags
);
7699 for_each_possible_cpu(i
) {
7700 register_fair_sched_group(tg
, i
);
7701 register_rt_sched_group(tg
, i
);
7703 list_add_rcu(&tg
->list
, &task_groups
);
7704 spin_unlock_irqrestore(&task_group_lock
, flags
);
7709 free_sched_group(tg
);
7710 return ERR_PTR(-ENOMEM
);
7713 /* rcu callback to free various structures associated with a task group */
7714 static void free_sched_group_rcu(struct rcu_head
*rhp
)
7716 /* now it should be safe to free those cfs_rqs */
7717 free_sched_group(container_of(rhp
, struct task_group
, rcu
));
7720 /* Destroy runqueue etc associated with a task group */
7721 void sched_destroy_group(struct task_group
*tg
)
7723 unsigned long flags
;
7726 spin_lock_irqsave(&task_group_lock
, flags
);
7727 for_each_possible_cpu(i
) {
7728 unregister_fair_sched_group(tg
, i
);
7729 unregister_rt_sched_group(tg
, i
);
7731 list_del_rcu(&tg
->list
);
7732 spin_unlock_irqrestore(&task_group_lock
, flags
);
7734 /* wait for possible concurrent references to cfs_rqs complete */
7735 call_rcu(&tg
->rcu
, free_sched_group_rcu
);
7738 /* change task's runqueue when it moves between groups.
7739 * The caller of this function should have put the task in its new group
7740 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7741 * reflect its new group.
7743 void sched_move_task(struct task_struct
*tsk
)
7746 unsigned long flags
;
7749 rq
= task_rq_lock(tsk
, &flags
);
7751 update_rq_clock(rq
);
7753 running
= task_current(rq
, tsk
);
7754 on_rq
= tsk
->se
.on_rq
;
7757 dequeue_task(rq
, tsk
, 0);
7758 if (unlikely(running
))
7759 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7761 set_task_rq(tsk
, task_cpu(tsk
));
7763 #ifdef CONFIG_FAIR_GROUP_SCHED
7764 if (tsk
->sched_class
->moved_group
)
7765 tsk
->sched_class
->moved_group(tsk
);
7768 if (unlikely(running
))
7769 tsk
->sched_class
->set_curr_task(rq
);
7771 enqueue_task(rq
, tsk
, 0);
7773 task_rq_unlock(rq
, &flags
);
7776 #ifdef CONFIG_FAIR_GROUP_SCHED
7777 static void set_se_shares(struct sched_entity
*se
, unsigned long shares
)
7779 struct cfs_rq
*cfs_rq
= se
->cfs_rq
;
7780 struct rq
*rq
= cfs_rq
->rq
;
7783 spin_lock_irq(&rq
->lock
);
7787 dequeue_entity(cfs_rq
, se
, 0);
7789 se
->load
.weight
= shares
;
7790 se
->load
.inv_weight
= div64_64((1ULL<<32), shares
);
7793 enqueue_entity(cfs_rq
, se
, 0);
7795 spin_unlock_irq(&rq
->lock
);
7798 static DEFINE_MUTEX(shares_mutex
);
7800 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
7803 unsigned long flags
;
7806 * A weight of 0 or 1 can cause arithmetics problems.
7807 * (The default weight is 1024 - so there's no practical
7808 * limitation from this.)
7813 mutex_lock(&shares_mutex
);
7814 if (tg
->shares
== shares
)
7817 spin_lock_irqsave(&task_group_lock
, flags
);
7818 for_each_possible_cpu(i
)
7819 unregister_fair_sched_group(tg
, i
);
7820 spin_unlock_irqrestore(&task_group_lock
, flags
);
7822 /* wait for any ongoing reference to this group to finish */
7823 synchronize_sched();
7826 * Now we are free to modify the group's share on each cpu
7827 * w/o tripping rebalance_share or load_balance_fair.
7829 tg
->shares
= shares
;
7830 for_each_possible_cpu(i
)
7831 set_se_shares(tg
->se
[i
], shares
);
7834 * Enable load balance activity on this group, by inserting it back on
7835 * each cpu's rq->leaf_cfs_rq_list.
7837 spin_lock_irqsave(&task_group_lock
, flags
);
7838 for_each_possible_cpu(i
)
7839 register_fair_sched_group(tg
, i
);
7840 spin_unlock_irqrestore(&task_group_lock
, flags
);
7842 mutex_unlock(&shares_mutex
);
7846 unsigned long sched_group_shares(struct task_group
*tg
)
7852 #ifdef CONFIG_RT_GROUP_SCHED
7854 * Ensure that the real time constraints are schedulable.
7856 static DEFINE_MUTEX(rt_constraints_mutex
);
7858 static unsigned long to_ratio(u64 period
, u64 runtime
)
7860 if (runtime
== RUNTIME_INF
)
7863 return div64_64(runtime
<< 16, period
);
7866 static int __rt_schedulable(struct task_group
*tg
, u64 period
, u64 runtime
)
7868 struct task_group
*tgi
;
7869 unsigned long total
= 0;
7870 unsigned long global_ratio
=
7871 to_ratio(sysctl_sched_rt_period
,
7872 sysctl_sched_rt_runtime
< 0 ?
7873 RUNTIME_INF
: sysctl_sched_rt_runtime
);
7876 list_for_each_entry_rcu(tgi
, &task_groups
, list
) {
7880 total
+= to_ratio(period
, tgi
->rt_runtime
);
7884 return total
+ to_ratio(period
, runtime
) < global_ratio
;
7887 /* Must be called with tasklist_lock held */
7888 static inline int tg_has_rt_tasks(struct task_group
*tg
)
7890 struct task_struct
*g
, *p
;
7891 do_each_thread(g
, p
) {
7892 if (rt_task(p
) && rt_rq_of_se(&p
->rt
)->tg
== tg
)
7894 } while_each_thread(g
, p
);
7898 int sched_group_set_rt_runtime(struct task_group
*tg
, long rt_runtime_us
)
7900 u64 rt_runtime
, rt_period
;
7903 rt_period
= (u64
)sysctl_sched_rt_period
* NSEC_PER_USEC
;
7904 rt_runtime
= (u64
)rt_runtime_us
* NSEC_PER_USEC
;
7905 if (rt_runtime_us
== -1)
7906 rt_runtime
= RUNTIME_INF
;
7908 mutex_lock(&rt_constraints_mutex
);
7909 read_lock(&tasklist_lock
);
7910 if (rt_runtime_us
== 0 && tg_has_rt_tasks(tg
)) {
7914 if (!__rt_schedulable(tg
, rt_period
, rt_runtime
)) {
7918 tg
->rt_runtime
= rt_runtime
;
7920 read_unlock(&tasklist_lock
);
7921 mutex_unlock(&rt_constraints_mutex
);
7926 long sched_group_rt_runtime(struct task_group
*tg
)
7930 if (tg
->rt_runtime
== RUNTIME_INF
)
7933 rt_runtime_us
= tg
->rt_runtime
;
7934 do_div(rt_runtime_us
, NSEC_PER_USEC
);
7935 return rt_runtime_us
;
7938 #endif /* CONFIG_GROUP_SCHED */
7940 #ifdef CONFIG_CGROUP_SCHED
7942 /* return corresponding task_group object of a cgroup */
7943 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7945 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7946 struct task_group
, css
);
7949 static struct cgroup_subsys_state
*
7950 cpu_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7952 struct task_group
*tg
;
7954 if (!cgrp
->parent
) {
7955 /* This is early initialization for the top cgroup */
7956 init_task_group
.css
.cgroup
= cgrp
;
7957 return &init_task_group
.css
;
7960 /* we support only 1-level deep hierarchical scheduler atm */
7961 if (cgrp
->parent
->parent
)
7962 return ERR_PTR(-EINVAL
);
7964 tg
= sched_create_group();
7966 return ERR_PTR(-ENOMEM
);
7968 /* Bind the cgroup to task_group object we just created */
7969 tg
->css
.cgroup
= cgrp
;
7975 cpu_cgroup_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7977 struct task_group
*tg
= cgroup_tg(cgrp
);
7979 sched_destroy_group(tg
);
7983 cpu_cgroup_can_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
7984 struct task_struct
*tsk
)
7986 #ifdef CONFIG_RT_GROUP_SCHED
7987 /* Don't accept realtime tasks when there is no way for them to run */
7988 if (rt_task(tsk
) && cgroup_tg(cgrp
)->rt_runtime
== 0)
7991 /* We don't support RT-tasks being in separate groups */
7992 if (tsk
->sched_class
!= &fair_sched_class
)
8000 cpu_cgroup_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
8001 struct cgroup
*old_cont
, struct task_struct
*tsk
)
8003 sched_move_task(tsk
);
8006 #ifdef CONFIG_FAIR_GROUP_SCHED
8007 static int cpu_shares_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
8010 return sched_group_set_shares(cgroup_tg(cgrp
), shareval
);
8013 static u64
cpu_shares_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
8015 struct task_group
*tg
= cgroup_tg(cgrp
);
8017 return (u64
) tg
->shares
;
8021 #ifdef CONFIG_RT_GROUP_SCHED
8022 static int cpu_rt_runtime_write(struct cgroup
*cgrp
, struct cftype
*cft
,
8024 const char __user
*userbuf
,
8025 size_t nbytes
, loff_t
*unused_ppos
)
8034 if (nbytes
>= sizeof(buffer
))
8036 if (copy_from_user(buffer
, userbuf
, nbytes
))
8039 buffer
[nbytes
] = 0; /* nul-terminate */
8041 /* strip newline if necessary */
8042 if (nbytes
&& (buffer
[nbytes
-1] == '\n'))
8043 buffer
[nbytes
-1] = 0;
8044 val
= simple_strtoll(buffer
, &end
, 0);
8048 /* Pass to subsystem */
8049 retval
= sched_group_set_rt_runtime(cgroup_tg(cgrp
), val
);
8055 static ssize_t
cpu_rt_runtime_read(struct cgroup
*cgrp
, struct cftype
*cft
,
8057 char __user
*buf
, size_t nbytes
,
8061 long val
= sched_group_rt_runtime(cgroup_tg(cgrp
));
8062 int len
= sprintf(tmp
, "%ld\n", val
);
8064 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
8068 static struct cftype cpu_files
[] = {
8069 #ifdef CONFIG_FAIR_GROUP_SCHED
8072 .read_uint
= cpu_shares_read_uint
,
8073 .write_uint
= cpu_shares_write_uint
,
8076 #ifdef CONFIG_RT_GROUP_SCHED
8078 .name
= "rt_runtime_us",
8079 .read
= cpu_rt_runtime_read
,
8080 .write
= cpu_rt_runtime_write
,
8085 static int cpu_cgroup_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8087 return cgroup_add_files(cont
, ss
, cpu_files
, ARRAY_SIZE(cpu_files
));
8090 struct cgroup_subsys cpu_cgroup_subsys
= {
8092 .create
= cpu_cgroup_create
,
8093 .destroy
= cpu_cgroup_destroy
,
8094 .can_attach
= cpu_cgroup_can_attach
,
8095 .attach
= cpu_cgroup_attach
,
8096 .populate
= cpu_cgroup_populate
,
8097 .subsys_id
= cpu_cgroup_subsys_id
,
8101 #endif /* CONFIG_CGROUP_SCHED */
8103 #ifdef CONFIG_CGROUP_CPUACCT
8106 * CPU accounting code for task groups.
8108 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
8109 * (balbir@in.ibm.com).
8112 /* track cpu usage of a group of tasks */
8114 struct cgroup_subsys_state css
;
8115 /* cpuusage holds pointer to a u64-type object on every cpu */
8119 struct cgroup_subsys cpuacct_subsys
;
8121 /* return cpu accounting group corresponding to this container */
8122 static inline struct cpuacct
*cgroup_ca(struct cgroup
*cont
)
8124 return container_of(cgroup_subsys_state(cont
, cpuacct_subsys_id
),
8125 struct cpuacct
, css
);
8128 /* return cpu accounting group to which this task belongs */
8129 static inline struct cpuacct
*task_ca(struct task_struct
*tsk
)
8131 return container_of(task_subsys_state(tsk
, cpuacct_subsys_id
),
8132 struct cpuacct
, css
);
8135 /* create a new cpu accounting group */
8136 static struct cgroup_subsys_state
*cpuacct_create(
8137 struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8139 struct cpuacct
*ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
8142 return ERR_PTR(-ENOMEM
);
8144 ca
->cpuusage
= alloc_percpu(u64
);
8145 if (!ca
->cpuusage
) {
8147 return ERR_PTR(-ENOMEM
);
8153 /* destroy an existing cpu accounting group */
8155 cpuacct_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8157 struct cpuacct
*ca
= cgroup_ca(cont
);
8159 free_percpu(ca
->cpuusage
);
8163 /* return total cpu usage (in nanoseconds) of a group */
8164 static u64
cpuusage_read(struct cgroup
*cont
, struct cftype
*cft
)
8166 struct cpuacct
*ca
= cgroup_ca(cont
);
8167 u64 totalcpuusage
= 0;
8170 for_each_possible_cpu(i
) {
8171 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, i
);
8174 * Take rq->lock to make 64-bit addition safe on 32-bit
8177 spin_lock_irq(&cpu_rq(i
)->lock
);
8178 totalcpuusage
+= *cpuusage
;
8179 spin_unlock_irq(&cpu_rq(i
)->lock
);
8182 return totalcpuusage
;
8185 static struct cftype files
[] = {
8188 .read_uint
= cpuusage_read
,
8192 static int cpuacct_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
8194 return cgroup_add_files(cont
, ss
, files
, ARRAY_SIZE(files
));
8198 * charge this task's execution time to its accounting group.
8200 * called with rq->lock held.
8202 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
)
8206 if (!cpuacct_subsys
.active
)
8211 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, task_cpu(tsk
));
8213 *cpuusage
+= cputime
;
8217 struct cgroup_subsys cpuacct_subsys
= {
8219 .create
= cpuacct_create
,
8220 .destroy
= cpuacct_destroy
,
8221 .populate
= cpuacct_populate
,
8222 .subsys_id
= cpuacct_subsys_id
,
8224 #endif /* CONFIG_CGROUP_CPUACCT */