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
28 #include <linux/module.h>
29 #include <linux/nmi.h>
30 #include <linux/init.h>
31 #include <linux/uaccess.h>
32 #include <linux/highmem.h>
33 #include <linux/smp_lock.h>
34 #include <asm/mmu_context.h>
35 #include <linux/interrupt.h>
36 #include <linux/capability.h>
37 #include <linux/completion.h>
38 #include <linux/kernel_stat.h>
39 #include <linux/debug_locks.h>
40 #include <linux/security.h>
41 #include <linux/notifier.h>
42 #include <linux/profile.h>
43 #include <linux/freezer.h>
44 #include <linux/vmalloc.h>
45 #include <linux/blkdev.h>
46 #include <linux/delay.h>
47 #include <linux/pid_namespace.h>
48 #include <linux/smp.h>
49 #include <linux/threads.h>
50 #include <linux/timer.h>
51 #include <linux/rcupdate.h>
52 #include <linux/cpu.h>
53 #include <linux/cpuset.h>
54 #include <linux/percpu.h>
55 #include <linux/kthread.h>
56 #include <linux/seq_file.h>
57 #include <linux/sysctl.h>
58 #include <linux/syscalls.h>
59 #include <linux/times.h>
60 #include <linux/tsacct_kern.h>
61 #include <linux/kprobes.h>
62 #include <linux/delayacct.h>
63 #include <linux/reciprocal_div.h>
64 #include <linux/unistd.h>
65 #include <linux/pagemap.h>
68 #include <asm/irq_regs.h>
71 * Scheduler clock - returns current time in nanosec units.
72 * This is default implementation.
73 * Architectures and sub-architectures can override this.
75 unsigned long long __attribute__((weak
)) sched_clock(void)
77 return (unsigned long long)jiffies
* (NSEC_PER_SEC
/ HZ
);
81 * Convert user-nice values [ -20 ... 0 ... 19 ]
82 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
85 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
86 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
87 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
90 * 'User priority' is the nice value converted to something we
91 * can work with better when scaling various scheduler parameters,
92 * it's a [ 0 ... 39 ] range.
94 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
95 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
96 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
99 * Some helpers for converting nanosecond timing to jiffy resolution
101 #define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
102 #define JIFFIES_TO_NS(TIME) ((TIME) * (NSEC_PER_SEC / HZ))
104 #define NICE_0_LOAD SCHED_LOAD_SCALE
105 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
108 * These are the 'tuning knobs' of the scheduler:
110 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
111 * Timeslices get refilled after they expire.
113 #define DEF_TIMESLICE (100 * HZ / 1000)
117 * Divide a load by a sched group cpu_power : (load / sg->__cpu_power)
118 * Since cpu_power is a 'constant', we can use a reciprocal divide.
120 static inline u32
sg_div_cpu_power(const struct sched_group
*sg
, u32 load
)
122 return reciprocal_divide(load
, sg
->reciprocal_cpu_power
);
126 * Each time a sched group cpu_power is changed,
127 * we must compute its reciprocal value
129 static inline void sg_inc_cpu_power(struct sched_group
*sg
, u32 val
)
131 sg
->__cpu_power
+= val
;
132 sg
->reciprocal_cpu_power
= reciprocal_value(sg
->__cpu_power
);
136 static inline int rt_policy(int policy
)
138 if (unlikely(policy
== SCHED_FIFO
) || unlikely(policy
== SCHED_RR
))
143 static inline int task_has_rt_policy(struct task_struct
*p
)
145 return rt_policy(p
->policy
);
149 * This is the priority-queue data structure of the RT scheduling class:
151 struct rt_prio_array
{
152 DECLARE_BITMAP(bitmap
, MAX_RT_PRIO
+1); /* include 1 bit for delimiter */
153 struct list_head queue
[MAX_RT_PRIO
];
156 #ifdef CONFIG_FAIR_GROUP_SCHED
158 #include <linux/cgroup.h>
162 /* task group related information */
164 #ifdef CONFIG_FAIR_CGROUP_SCHED
165 struct cgroup_subsys_state css
;
167 /* schedulable entities of this group on each cpu */
168 struct sched_entity
**se
;
169 /* runqueue "owned" by this group on each cpu */
170 struct cfs_rq
**cfs_rq
;
171 unsigned long shares
;
175 /* Default task group's sched entity on each cpu */
176 static DEFINE_PER_CPU(struct sched_entity
, init_sched_entity
);
177 /* Default task group's cfs_rq on each cpu */
178 static DEFINE_PER_CPU(struct cfs_rq
, init_cfs_rq
) ____cacheline_aligned_in_smp
;
180 static struct sched_entity
*init_sched_entity_p
[NR_CPUS
];
181 static struct cfs_rq
*init_cfs_rq_p
[NR_CPUS
];
183 /* task_group_mutex serializes add/remove of task groups and also changes to
184 * a task group's cpu shares.
186 static DEFINE_MUTEX(task_group_mutex
);
188 /* doms_cur_mutex serializes access to doms_cur[] array */
189 static DEFINE_MUTEX(doms_cur_mutex
);
191 /* Default task group.
192 * Every task in system belong to this group at bootup.
194 struct task_group init_task_group
= {
195 .se
= init_sched_entity_p
,
196 .cfs_rq
= init_cfs_rq_p
,
199 #ifdef CONFIG_FAIR_USER_SCHED
200 # define INIT_TASK_GROUP_LOAD 2*NICE_0_LOAD
202 # define INIT_TASK_GROUP_LOAD NICE_0_LOAD
205 static int init_task_group_load
= INIT_TASK_GROUP_LOAD
;
207 /* return group to which a task belongs */
208 static inline struct task_group
*task_group(struct task_struct
*p
)
210 struct task_group
*tg
;
212 #ifdef CONFIG_FAIR_USER_SCHED
214 #elif defined(CONFIG_FAIR_CGROUP_SCHED)
215 tg
= container_of(task_subsys_state(p
, cpu_cgroup_subsys_id
),
216 struct task_group
, css
);
218 tg
= &init_task_group
;
223 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
224 static inline void set_task_cfs_rq(struct task_struct
*p
, unsigned int cpu
)
226 p
->se
.cfs_rq
= task_group(p
)->cfs_rq
[cpu
];
227 p
->se
.parent
= task_group(p
)->se
[cpu
];
230 static inline void lock_task_group_list(void)
232 mutex_lock(&task_group_mutex
);
235 static inline void unlock_task_group_list(void)
237 mutex_unlock(&task_group_mutex
);
240 static inline void lock_doms_cur(void)
242 mutex_lock(&doms_cur_mutex
);
245 static inline void unlock_doms_cur(void)
247 mutex_unlock(&doms_cur_mutex
);
252 static inline void set_task_cfs_rq(struct task_struct
*p
, unsigned int cpu
) { }
253 static inline void lock_task_group_list(void) { }
254 static inline void unlock_task_group_list(void) { }
255 static inline void lock_doms_cur(void) { }
256 static inline void unlock_doms_cur(void) { }
258 #endif /* CONFIG_FAIR_GROUP_SCHED */
260 /* CFS-related fields in a runqueue */
262 struct load_weight load
;
263 unsigned long nr_running
;
268 struct rb_root tasks_timeline
;
269 struct rb_node
*rb_leftmost
;
270 struct rb_node
*rb_load_balance_curr
;
271 /* 'curr' points to currently running entity on this cfs_rq.
272 * It is set to NULL otherwise (i.e when none are currently running).
274 struct sched_entity
*curr
;
276 unsigned long nr_spread_over
;
278 #ifdef CONFIG_FAIR_GROUP_SCHED
279 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
282 * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
283 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
284 * (like users, containers etc.)
286 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
287 * list is used during load balance.
289 struct list_head leaf_cfs_rq_list
;
290 struct task_group
*tg
; /* group that "owns" this runqueue */
294 /* Real-Time classes' related field in a runqueue: */
296 struct rt_prio_array active
;
297 int rt_load_balance_idx
;
298 struct list_head
*rt_load_balance_head
, *rt_load_balance_curr
;
302 * This is the main, per-CPU runqueue data structure.
304 * Locking rule: those places that want to lock multiple runqueues
305 * (such as the load balancing or the thread migration code), lock
306 * acquire operations must be ordered by ascending &runqueue.
313 * nr_running and cpu_load should be in the same cacheline because
314 * remote CPUs use both these fields when doing load calculation.
316 unsigned long nr_running
;
317 #define CPU_LOAD_IDX_MAX 5
318 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
319 unsigned char idle_at_tick
;
321 unsigned char in_nohz_recently
;
323 /* capture load from *all* tasks on this cpu: */
324 struct load_weight load
;
325 unsigned long nr_load_updates
;
329 #ifdef CONFIG_FAIR_GROUP_SCHED
330 /* list of leaf cfs_rq on this cpu: */
331 struct list_head leaf_cfs_rq_list
;
336 * This is part of a global counter where only the total sum
337 * over all CPUs matters. A task can increase this counter on
338 * one CPU and if it got migrated afterwards it may decrease
339 * it on another CPU. Always updated under the runqueue lock:
341 unsigned long nr_uninterruptible
;
343 struct task_struct
*curr
, *idle
;
344 unsigned long next_balance
;
345 struct mm_struct
*prev_mm
;
347 u64 clock
, prev_clock_raw
;
350 unsigned int clock_warps
, clock_overflows
;
352 unsigned int clock_deep_idle_events
;
358 struct sched_domain
*sd
;
360 /* For active balancing */
363 /* cpu of this runqueue: */
366 struct task_struct
*migration_thread
;
367 struct list_head migration_queue
;
370 #ifdef CONFIG_SCHEDSTATS
372 struct sched_info rq_sched_info
;
374 /* sys_sched_yield() stats */
375 unsigned int yld_exp_empty
;
376 unsigned int yld_act_empty
;
377 unsigned int yld_both_empty
;
378 unsigned int yld_count
;
380 /* schedule() stats */
381 unsigned int sched_switch
;
382 unsigned int sched_count
;
383 unsigned int sched_goidle
;
385 /* try_to_wake_up() stats */
386 unsigned int ttwu_count
;
387 unsigned int ttwu_local
;
390 unsigned int bkl_count
;
392 struct lock_class_key rq_lock_key
;
395 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
396 static DEFINE_MUTEX(sched_hotcpu_mutex
);
398 static inline void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
)
400 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
);
403 static inline int cpu_of(struct rq
*rq
)
413 * Update the per-runqueue clock, as finegrained as the platform can give
414 * us, but without assuming monotonicity, etc.:
416 static void __update_rq_clock(struct rq
*rq
)
418 u64 prev_raw
= rq
->prev_clock_raw
;
419 u64 now
= sched_clock();
420 s64 delta
= now
- prev_raw
;
421 u64 clock
= rq
->clock
;
423 #ifdef CONFIG_SCHED_DEBUG
424 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
427 * Protect against sched_clock() occasionally going backwards:
429 if (unlikely(delta
< 0)) {
434 * Catch too large forward jumps too:
436 if (unlikely(clock
+ delta
> rq
->tick_timestamp
+ TICK_NSEC
)) {
437 if (clock
< rq
->tick_timestamp
+ TICK_NSEC
)
438 clock
= rq
->tick_timestamp
+ TICK_NSEC
;
441 rq
->clock_overflows
++;
443 if (unlikely(delta
> rq
->clock_max_delta
))
444 rq
->clock_max_delta
= delta
;
449 rq
->prev_clock_raw
= now
;
453 static void update_rq_clock(struct rq
*rq
)
455 if (likely(smp_processor_id() == cpu_of(rq
)))
456 __update_rq_clock(rq
);
460 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
461 * See detach_destroy_domains: synchronize_sched for details.
463 * The domain tree of any CPU may only be accessed from within
464 * preempt-disabled sections.
466 #define for_each_domain(cpu, __sd) \
467 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
469 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
470 #define this_rq() (&__get_cpu_var(runqueues))
471 #define task_rq(p) cpu_rq(task_cpu(p))
472 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
475 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
477 #ifdef CONFIG_SCHED_DEBUG
478 # define const_debug __read_mostly
480 # define const_debug static const
484 * Debugging: various feature bits
487 SCHED_FEAT_NEW_FAIR_SLEEPERS
= 1,
488 SCHED_FEAT_WAKEUP_PREEMPT
= 2,
489 SCHED_FEAT_START_DEBIT
= 4,
490 SCHED_FEAT_TREE_AVG
= 8,
491 SCHED_FEAT_APPROX_AVG
= 16,
494 const_debug
unsigned int sysctl_sched_features
=
495 SCHED_FEAT_NEW_FAIR_SLEEPERS
* 1 |
496 SCHED_FEAT_WAKEUP_PREEMPT
* 1 |
497 SCHED_FEAT_START_DEBIT
* 1 |
498 SCHED_FEAT_TREE_AVG
* 0 |
499 SCHED_FEAT_APPROX_AVG
* 0;
501 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
504 * Number of tasks to iterate in a single balance run.
505 * Limited because this is done with IRQs disabled.
507 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
510 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
511 * clock constructed from sched_clock():
513 unsigned long long cpu_clock(int cpu
)
515 unsigned long long now
;
519 local_irq_save(flags
);
522 * Only call sched_clock() if the scheduler has already been
523 * initialized (some code might call cpu_clock() very early):
528 local_irq_restore(flags
);
532 EXPORT_SYMBOL_GPL(cpu_clock
);
534 #ifndef prepare_arch_switch
535 # define prepare_arch_switch(next) do { } while (0)
537 #ifndef finish_arch_switch
538 # define finish_arch_switch(prev) do { } while (0)
541 static inline int task_current(struct rq
*rq
, struct task_struct
*p
)
543 return rq
->curr
== p
;
546 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
547 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
549 return task_current(rq
, p
);
552 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
556 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
558 #ifdef CONFIG_DEBUG_SPINLOCK
559 /* this is a valid case when another task releases the spinlock */
560 rq
->lock
.owner
= current
;
563 * If we are tracking spinlock dependencies then we have to
564 * fix up the runqueue lock - which gets 'carried over' from
567 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
569 spin_unlock_irq(&rq
->lock
);
572 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
573 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
578 return task_current(rq
, p
);
582 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
586 * We can optimise this out completely for !SMP, because the
587 * SMP rebalancing from interrupt is the only thing that cares
592 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
593 spin_unlock_irq(&rq
->lock
);
595 spin_unlock(&rq
->lock
);
599 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
603 * After ->oncpu is cleared, the task can be moved to a different CPU.
604 * We must ensure this doesn't happen until the switch is completely
610 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
614 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
617 * __task_rq_lock - lock the runqueue a given task resides on.
618 * Must be called interrupts disabled.
620 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
624 struct rq
*rq
= task_rq(p
);
625 spin_lock(&rq
->lock
);
626 if (likely(rq
== task_rq(p
)))
628 spin_unlock(&rq
->lock
);
633 * task_rq_lock - lock the runqueue a given task resides on and disable
634 * interrupts. Note the ordering: we can safely lookup the task_rq without
635 * explicitly disabling preemption.
637 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
643 local_irq_save(*flags
);
645 spin_lock(&rq
->lock
);
646 if (likely(rq
== task_rq(p
)))
648 spin_unlock_irqrestore(&rq
->lock
, *flags
);
652 static void __task_rq_unlock(struct rq
*rq
)
655 spin_unlock(&rq
->lock
);
658 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
661 spin_unlock_irqrestore(&rq
->lock
, *flags
);
665 * this_rq_lock - lock this runqueue and disable interrupts.
667 static struct rq
*this_rq_lock(void)
674 spin_lock(&rq
->lock
);
680 * We are going deep-idle (irqs are disabled):
682 void sched_clock_idle_sleep_event(void)
684 struct rq
*rq
= cpu_rq(smp_processor_id());
686 spin_lock(&rq
->lock
);
687 __update_rq_clock(rq
);
688 spin_unlock(&rq
->lock
);
689 rq
->clock_deep_idle_events
++;
691 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
694 * We just idled delta nanoseconds (called with irqs disabled):
696 void sched_clock_idle_wakeup_event(u64 delta_ns
)
698 struct rq
*rq
= cpu_rq(smp_processor_id());
699 u64 now
= sched_clock();
701 touch_softlockup_watchdog();
702 rq
->idle_clock
+= delta_ns
;
704 * Override the previous timestamp and ignore all
705 * sched_clock() deltas that occured while we idled,
706 * and use the PM-provided delta_ns to advance the
709 spin_lock(&rq
->lock
);
710 rq
->prev_clock_raw
= now
;
711 rq
->clock
+= delta_ns
;
712 spin_unlock(&rq
->lock
);
714 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
717 * resched_task - mark a task 'to be rescheduled now'.
719 * On UP this means the setting of the need_resched flag, on SMP it
720 * might also involve a cross-CPU call to trigger the scheduler on
725 #ifndef tsk_is_polling
726 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
729 static void resched_task(struct task_struct
*p
)
733 assert_spin_locked(&task_rq(p
)->lock
);
735 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
738 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
741 if (cpu
== smp_processor_id())
744 /* NEED_RESCHED must be visible before we test polling */
746 if (!tsk_is_polling(p
))
747 smp_send_reschedule(cpu
);
750 static void resched_cpu(int cpu
)
752 struct rq
*rq
= cpu_rq(cpu
);
755 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
757 resched_task(cpu_curr(cpu
));
758 spin_unlock_irqrestore(&rq
->lock
, flags
);
761 static inline void resched_task(struct task_struct
*p
)
763 assert_spin_locked(&task_rq(p
)->lock
);
764 set_tsk_need_resched(p
);
768 #if BITS_PER_LONG == 32
769 # define WMULT_CONST (~0UL)
771 # define WMULT_CONST (1UL << 32)
774 #define WMULT_SHIFT 32
777 * Shift right and round:
779 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
782 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
783 struct load_weight
*lw
)
787 if (unlikely(!lw
->inv_weight
))
788 lw
->inv_weight
= (WMULT_CONST
- lw
->weight
/2) / lw
->weight
+ 1;
790 tmp
= (u64
)delta_exec
* weight
;
792 * Check whether we'd overflow the 64-bit multiplication:
794 if (unlikely(tmp
> WMULT_CONST
))
795 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
798 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
800 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
803 static inline unsigned long
804 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
806 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
809 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
814 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
820 * To aid in avoiding the subversion of "niceness" due to uneven distribution
821 * of tasks with abnormal "nice" values across CPUs the contribution that
822 * each task makes to its run queue's load is weighted according to its
823 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
824 * scaled version of the new time slice allocation that they receive on time
828 #define WEIGHT_IDLEPRIO 2
829 #define WMULT_IDLEPRIO (1 << 31)
832 * Nice levels are multiplicative, with a gentle 10% change for every
833 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
834 * nice 1, it will get ~10% less CPU time than another CPU-bound task
835 * that remained on nice 0.
837 * The "10% effect" is relative and cumulative: from _any_ nice level,
838 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
839 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
840 * If a task goes up by ~10% and another task goes down by ~10% then
841 * the relative distance between them is ~25%.)
843 static const int prio_to_weight
[40] = {
844 /* -20 */ 88761, 71755, 56483, 46273, 36291,
845 /* -15 */ 29154, 23254, 18705, 14949, 11916,
846 /* -10 */ 9548, 7620, 6100, 4904, 3906,
847 /* -5 */ 3121, 2501, 1991, 1586, 1277,
848 /* 0 */ 1024, 820, 655, 526, 423,
849 /* 5 */ 335, 272, 215, 172, 137,
850 /* 10 */ 110, 87, 70, 56, 45,
851 /* 15 */ 36, 29, 23, 18, 15,
855 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
857 * In cases where the weight does not change often, we can use the
858 * precalculated inverse to speed up arithmetics by turning divisions
859 * into multiplications:
861 static const u32 prio_to_wmult
[40] = {
862 /* -20 */ 48388, 59856, 76040, 92818, 118348,
863 /* -15 */ 147320, 184698, 229616, 287308, 360437,
864 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
865 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
866 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
867 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
868 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
869 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
872 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
875 * runqueue iterator, to support SMP load-balancing between different
876 * scheduling classes, without having to expose their internal data
877 * structures to the load-balancing proper:
881 struct task_struct
*(*start
)(void *);
882 struct task_struct
*(*next
)(void *);
887 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
888 unsigned long max_load_move
, struct sched_domain
*sd
,
889 enum cpu_idle_type idle
, int *all_pinned
,
890 int *this_best_prio
, struct rq_iterator
*iterator
);
893 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
894 struct sched_domain
*sd
, enum cpu_idle_type idle
,
895 struct rq_iterator
*iterator
);
898 #ifdef CONFIG_CGROUP_CPUACCT
899 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
);
901 static inline void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
) {}
904 static inline void inc_cpu_load(struct rq
*rq
, unsigned long load
)
906 update_load_add(&rq
->load
, load
);
909 static inline void dec_cpu_load(struct rq
*rq
, unsigned long load
)
911 update_load_sub(&rq
->load
, load
);
914 #include "sched_stats.h"
915 #include "sched_idletask.c"
916 #include "sched_fair.c"
917 #include "sched_rt.c"
918 #ifdef CONFIG_SCHED_DEBUG
919 # include "sched_debug.c"
922 #define sched_class_highest (&rt_sched_class)
924 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
929 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
934 static void set_load_weight(struct task_struct
*p
)
936 if (task_has_rt_policy(p
)) {
937 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
938 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
943 * SCHED_IDLE tasks get minimal weight:
945 if (p
->policy
== SCHED_IDLE
) {
946 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
947 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
951 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
952 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
955 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
957 sched_info_queued(p
);
958 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
962 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
964 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
969 * __normal_prio - return the priority that is based on the static prio
971 static inline int __normal_prio(struct task_struct
*p
)
973 return p
->static_prio
;
977 * Calculate the expected normal priority: i.e. priority
978 * without taking RT-inheritance into account. Might be
979 * boosted by interactivity modifiers. Changes upon fork,
980 * setprio syscalls, and whenever the interactivity
981 * estimator recalculates.
983 static inline int normal_prio(struct task_struct
*p
)
987 if (task_has_rt_policy(p
))
988 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
990 prio
= __normal_prio(p
);
995 * Calculate the current priority, i.e. the priority
996 * taken into account by the scheduler. This value might
997 * be boosted by RT tasks, or might be boosted by
998 * interactivity modifiers. Will be RT if the task got
999 * RT-boosted. If not then it returns p->normal_prio.
1001 static int effective_prio(struct task_struct
*p
)
1003 p
->normal_prio
= normal_prio(p
);
1005 * If we are RT tasks or we were boosted to RT priority,
1006 * keep the priority unchanged. Otherwise, update priority
1007 * to the normal priority:
1009 if (!rt_prio(p
->prio
))
1010 return p
->normal_prio
;
1015 * activate_task - move a task to the runqueue.
1017 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
1019 if (p
->state
== TASK_UNINTERRUPTIBLE
)
1020 rq
->nr_uninterruptible
--;
1022 enqueue_task(rq
, p
, wakeup
);
1023 inc_nr_running(p
, rq
);
1027 * deactivate_task - remove a task from the runqueue.
1029 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1031 if (p
->state
== TASK_UNINTERRUPTIBLE
)
1032 rq
->nr_uninterruptible
++;
1034 dequeue_task(rq
, p
, sleep
);
1035 dec_nr_running(p
, rq
);
1039 * task_curr - is this task currently executing on a CPU?
1040 * @p: the task in question.
1042 inline int task_curr(const struct task_struct
*p
)
1044 return cpu_curr(task_cpu(p
)) == p
;
1047 /* Used instead of source_load when we know the type == 0 */
1048 unsigned long weighted_cpuload(const int cpu
)
1050 return cpu_rq(cpu
)->load
.weight
;
1053 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
1055 set_task_cfs_rq(p
, cpu
);
1058 * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1059 * successfuly executed on another CPU. We must ensure that updates of
1060 * per-task data have been completed by this moment.
1063 task_thread_info(p
)->cpu
= cpu
;
1070 * Is this task likely cache-hot:
1073 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
1077 if (p
->sched_class
!= &fair_sched_class
)
1080 if (sysctl_sched_migration_cost
== -1)
1082 if (sysctl_sched_migration_cost
== 0)
1085 delta
= now
- p
->se
.exec_start
;
1087 return delta
< (s64
)sysctl_sched_migration_cost
;
1091 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1093 int old_cpu
= task_cpu(p
);
1094 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
1095 struct cfs_rq
*old_cfsrq
= task_cfs_rq(p
),
1096 *new_cfsrq
= cpu_cfs_rq(old_cfsrq
, new_cpu
);
1099 clock_offset
= old_rq
->clock
- new_rq
->clock
;
1101 #ifdef CONFIG_SCHEDSTATS
1102 if (p
->se
.wait_start
)
1103 p
->se
.wait_start
-= clock_offset
;
1104 if (p
->se
.sleep_start
)
1105 p
->se
.sleep_start
-= clock_offset
;
1106 if (p
->se
.block_start
)
1107 p
->se
.block_start
-= clock_offset
;
1108 if (old_cpu
!= new_cpu
) {
1109 schedstat_inc(p
, se
.nr_migrations
);
1110 if (task_hot(p
, old_rq
->clock
, NULL
))
1111 schedstat_inc(p
, se
.nr_forced2_migrations
);
1114 p
->se
.vruntime
-= old_cfsrq
->min_vruntime
-
1115 new_cfsrq
->min_vruntime
;
1117 __set_task_cpu(p
, new_cpu
);
1120 struct migration_req
{
1121 struct list_head list
;
1123 struct task_struct
*task
;
1126 struct completion done
;
1130 * The task's runqueue lock must be held.
1131 * Returns true if you have to wait for migration thread.
1134 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1136 struct rq
*rq
= task_rq(p
);
1139 * If the task is not on a runqueue (and not running), then
1140 * it is sufficient to simply update the task's cpu field.
1142 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1143 set_task_cpu(p
, dest_cpu
);
1147 init_completion(&req
->done
);
1149 req
->dest_cpu
= dest_cpu
;
1150 list_add(&req
->list
, &rq
->migration_queue
);
1156 * wait_task_inactive - wait for a thread to unschedule.
1158 * The caller must ensure that the task *will* unschedule sometime soon,
1159 * else this function might spin for a *long* time. This function can't
1160 * be called with interrupts off, or it may introduce deadlock with
1161 * smp_call_function() if an IPI is sent by the same process we are
1162 * waiting to become inactive.
1164 void wait_task_inactive(struct task_struct
*p
)
1166 unsigned long flags
;
1172 * We do the initial early heuristics without holding
1173 * any task-queue locks at all. We'll only try to get
1174 * the runqueue lock when things look like they will
1180 * If the task is actively running on another CPU
1181 * still, just relax and busy-wait without holding
1184 * NOTE! Since we don't hold any locks, it's not
1185 * even sure that "rq" stays as the right runqueue!
1186 * But we don't care, since "task_running()" will
1187 * return false if the runqueue has changed and p
1188 * is actually now running somewhere else!
1190 while (task_running(rq
, p
))
1194 * Ok, time to look more closely! We need the rq
1195 * lock now, to be *sure*. If we're wrong, we'll
1196 * just go back and repeat.
1198 rq
= task_rq_lock(p
, &flags
);
1199 running
= task_running(rq
, p
);
1200 on_rq
= p
->se
.on_rq
;
1201 task_rq_unlock(rq
, &flags
);
1204 * Was it really running after all now that we
1205 * checked with the proper locks actually held?
1207 * Oops. Go back and try again..
1209 if (unlikely(running
)) {
1215 * It's not enough that it's not actively running,
1216 * it must be off the runqueue _entirely_, and not
1219 * So if it wa still runnable (but just not actively
1220 * running right now), it's preempted, and we should
1221 * yield - it could be a while.
1223 if (unlikely(on_rq
)) {
1224 schedule_timeout_uninterruptible(1);
1229 * Ahh, all good. It wasn't running, and it wasn't
1230 * runnable, which means that it will never become
1231 * running in the future either. We're all done!
1238 * kick_process - kick a running thread to enter/exit the kernel
1239 * @p: the to-be-kicked thread
1241 * Cause a process which is running on another CPU to enter
1242 * kernel-mode, without any delay. (to get signals handled.)
1244 * NOTE: this function doesnt have to take the runqueue lock,
1245 * because all it wants to ensure is that the remote task enters
1246 * the kernel. If the IPI races and the task has been migrated
1247 * to another CPU then no harm is done and the purpose has been
1250 void kick_process(struct task_struct
*p
)
1256 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1257 smp_send_reschedule(cpu
);
1262 * Return a low guess at the load of a migration-source cpu weighted
1263 * according to the scheduling class and "nice" value.
1265 * We want to under-estimate the load of migration sources, to
1266 * balance conservatively.
1268 static unsigned long source_load(int cpu
, int type
)
1270 struct rq
*rq
= cpu_rq(cpu
);
1271 unsigned long total
= weighted_cpuload(cpu
);
1276 return min(rq
->cpu_load
[type
-1], total
);
1280 * Return a high guess at the load of a migration-target cpu weighted
1281 * according to the scheduling class and "nice" value.
1283 static unsigned long target_load(int cpu
, int type
)
1285 struct rq
*rq
= cpu_rq(cpu
);
1286 unsigned long total
= weighted_cpuload(cpu
);
1291 return max(rq
->cpu_load
[type
-1], total
);
1295 * Return the average load per task on the cpu's run queue
1297 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1299 struct rq
*rq
= cpu_rq(cpu
);
1300 unsigned long total
= weighted_cpuload(cpu
);
1301 unsigned long n
= rq
->nr_running
;
1303 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1307 * find_idlest_group finds and returns the least busy CPU group within the
1310 static struct sched_group
*
1311 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1313 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1314 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1315 int load_idx
= sd
->forkexec_idx
;
1316 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1319 unsigned long load
, avg_load
;
1323 /* Skip over this group if it has no CPUs allowed */
1324 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1327 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1329 /* Tally up the load of all CPUs in the group */
1332 for_each_cpu_mask(i
, group
->cpumask
) {
1333 /* Bias balancing toward cpus of our domain */
1335 load
= source_load(i
, load_idx
);
1337 load
= target_load(i
, load_idx
);
1342 /* Adjust by relative CPU power of the group */
1343 avg_load
= sg_div_cpu_power(group
,
1344 avg_load
* SCHED_LOAD_SCALE
);
1347 this_load
= avg_load
;
1349 } else if (avg_load
< min_load
) {
1350 min_load
= avg_load
;
1353 } while (group
= group
->next
, group
!= sd
->groups
);
1355 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1361 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1364 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1367 unsigned long load
, min_load
= ULONG_MAX
;
1371 /* Traverse only the allowed CPUs */
1372 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1374 for_each_cpu_mask(i
, tmp
) {
1375 load
= weighted_cpuload(i
);
1377 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1387 * sched_balance_self: balance the current task (running on cpu) in domains
1388 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1391 * Balance, ie. select the least loaded group.
1393 * Returns the target CPU number, or the same CPU if no balancing is needed.
1395 * preempt must be disabled.
1397 static int sched_balance_self(int cpu
, int flag
)
1399 struct task_struct
*t
= current
;
1400 struct sched_domain
*tmp
, *sd
= NULL
;
1402 for_each_domain(cpu
, tmp
) {
1404 * If power savings logic is enabled for a domain, stop there.
1406 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1408 if (tmp
->flags
& flag
)
1414 struct sched_group
*group
;
1415 int new_cpu
, weight
;
1417 if (!(sd
->flags
& flag
)) {
1423 group
= find_idlest_group(sd
, t
, cpu
);
1429 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1430 if (new_cpu
== -1 || new_cpu
== cpu
) {
1431 /* Now try balancing at a lower domain level of cpu */
1436 /* Now try balancing at a lower domain level of new_cpu */
1439 weight
= cpus_weight(span
);
1440 for_each_domain(cpu
, tmp
) {
1441 if (weight
<= cpus_weight(tmp
->span
))
1443 if (tmp
->flags
& flag
)
1446 /* while loop will break here if sd == NULL */
1452 #endif /* CONFIG_SMP */
1455 * wake_idle() will wake a task on an idle cpu if task->cpu is
1456 * not idle and an idle cpu is available. The span of cpus to
1457 * search starts with cpus closest then further out as needed,
1458 * so we always favor a closer, idle cpu.
1460 * Returns the CPU we should wake onto.
1462 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1463 static int wake_idle(int cpu
, struct task_struct
*p
)
1466 struct sched_domain
*sd
;
1470 * If it is idle, then it is the best cpu to run this task.
1472 * This cpu is also the best, if it has more than one task already.
1473 * Siblings must be also busy(in most cases) as they didn't already
1474 * pickup the extra load from this cpu and hence we need not check
1475 * sibling runqueue info. This will avoid the checks and cache miss
1476 * penalities associated with that.
1478 if (idle_cpu(cpu
) || cpu_rq(cpu
)->nr_running
> 1)
1481 for_each_domain(cpu
, sd
) {
1482 if (sd
->flags
& SD_WAKE_IDLE
) {
1483 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1484 for_each_cpu_mask(i
, tmp
) {
1486 if (i
!= task_cpu(p
)) {
1488 se
.nr_wakeups_idle
);
1500 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1507 * try_to_wake_up - wake up a thread
1508 * @p: the to-be-woken-up thread
1509 * @state: the mask of task states that can be woken
1510 * @sync: do a synchronous wakeup?
1512 * Put it on the run-queue if it's not already there. The "current"
1513 * thread is always on the run-queue (except when the actual
1514 * re-schedule is in progress), and as such you're allowed to do
1515 * the simpler "current->state = TASK_RUNNING" to mark yourself
1516 * runnable without the overhead of this.
1518 * returns failure only if the task is already active.
1520 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1522 int cpu
, orig_cpu
, this_cpu
, success
= 0;
1523 unsigned long flags
;
1527 struct sched_domain
*sd
, *this_sd
= NULL
;
1528 unsigned long load
, this_load
;
1532 rq
= task_rq_lock(p
, &flags
);
1533 old_state
= p
->state
;
1534 if (!(old_state
& state
))
1542 this_cpu
= smp_processor_id();
1545 if (unlikely(task_running(rq
, p
)))
1550 schedstat_inc(rq
, ttwu_count
);
1551 if (cpu
== this_cpu
) {
1552 schedstat_inc(rq
, ttwu_local
);
1556 for_each_domain(this_cpu
, sd
) {
1557 if (cpu_isset(cpu
, sd
->span
)) {
1558 schedstat_inc(sd
, ttwu_wake_remote
);
1564 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1568 * Check for affine wakeup and passive balancing possibilities.
1571 int idx
= this_sd
->wake_idx
;
1572 unsigned int imbalance
;
1574 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1576 load
= source_load(cpu
, idx
);
1577 this_load
= target_load(this_cpu
, idx
);
1579 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1581 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1582 unsigned long tl
= this_load
;
1583 unsigned long tl_per_task
;
1586 * Attract cache-cold tasks on sync wakeups:
1588 if (sync
&& !task_hot(p
, rq
->clock
, this_sd
))
1591 schedstat_inc(p
, se
.nr_wakeups_affine_attempts
);
1592 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1595 * If sync wakeup then subtract the (maximum possible)
1596 * effect of the currently running task from the load
1597 * of the current CPU:
1600 tl
-= current
->se
.load
.weight
;
1603 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1604 100*(tl
+ p
->se
.load
.weight
) <= imbalance
*load
) {
1606 * This domain has SD_WAKE_AFFINE and
1607 * p is cache cold in this domain, and
1608 * there is no bad imbalance.
1610 schedstat_inc(this_sd
, ttwu_move_affine
);
1611 schedstat_inc(p
, se
.nr_wakeups_affine
);
1617 * Start passive balancing when half the imbalance_pct
1620 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1621 if (imbalance
*this_load
<= 100*load
) {
1622 schedstat_inc(this_sd
, ttwu_move_balance
);
1623 schedstat_inc(p
, se
.nr_wakeups_passive
);
1629 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1631 new_cpu
= wake_idle(new_cpu
, p
);
1632 if (new_cpu
!= cpu
) {
1633 set_task_cpu(p
, new_cpu
);
1634 task_rq_unlock(rq
, &flags
);
1635 /* might preempt at this point */
1636 rq
= task_rq_lock(p
, &flags
);
1637 old_state
= p
->state
;
1638 if (!(old_state
& state
))
1643 this_cpu
= smp_processor_id();
1648 #endif /* CONFIG_SMP */
1649 schedstat_inc(p
, se
.nr_wakeups
);
1651 schedstat_inc(p
, se
.nr_wakeups_sync
);
1652 if (orig_cpu
!= cpu
)
1653 schedstat_inc(p
, se
.nr_wakeups_migrate
);
1654 if (cpu
== this_cpu
)
1655 schedstat_inc(p
, se
.nr_wakeups_local
);
1657 schedstat_inc(p
, se
.nr_wakeups_remote
);
1658 update_rq_clock(rq
);
1659 activate_task(rq
, p
, 1);
1660 check_preempt_curr(rq
, p
);
1664 p
->state
= TASK_RUNNING
;
1666 task_rq_unlock(rq
, &flags
);
1671 int fastcall
wake_up_process(struct task_struct
*p
)
1673 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1674 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1676 EXPORT_SYMBOL(wake_up_process
);
1678 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1680 return try_to_wake_up(p
, state
, 0);
1684 * Perform scheduler related setup for a newly forked process p.
1685 * p is forked by current.
1687 * __sched_fork() is basic setup used by init_idle() too:
1689 static void __sched_fork(struct task_struct
*p
)
1691 p
->se
.exec_start
= 0;
1692 p
->se
.sum_exec_runtime
= 0;
1693 p
->se
.prev_sum_exec_runtime
= 0;
1695 #ifdef CONFIG_SCHEDSTATS
1696 p
->se
.wait_start
= 0;
1697 p
->se
.sum_sleep_runtime
= 0;
1698 p
->se
.sleep_start
= 0;
1699 p
->se
.block_start
= 0;
1700 p
->se
.sleep_max
= 0;
1701 p
->se
.block_max
= 0;
1703 p
->se
.slice_max
= 0;
1707 INIT_LIST_HEAD(&p
->run_list
);
1710 #ifdef CONFIG_PREEMPT_NOTIFIERS
1711 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1715 * We mark the process as running here, but have not actually
1716 * inserted it onto the runqueue yet. This guarantees that
1717 * nobody will actually run it, and a signal or other external
1718 * event cannot wake it up and insert it on the runqueue either.
1720 p
->state
= TASK_RUNNING
;
1724 * fork()/clone()-time setup:
1726 void sched_fork(struct task_struct
*p
, int clone_flags
)
1728 int cpu
= get_cpu();
1733 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1735 set_task_cpu(p
, cpu
);
1738 * Make sure we do not leak PI boosting priority to the child:
1740 p
->prio
= current
->normal_prio
;
1741 if (!rt_prio(p
->prio
))
1742 p
->sched_class
= &fair_sched_class
;
1744 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1745 if (likely(sched_info_on()))
1746 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1748 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1751 #ifdef CONFIG_PREEMPT
1752 /* Want to start with kernel preemption disabled. */
1753 task_thread_info(p
)->preempt_count
= 1;
1759 * wake_up_new_task - wake up a newly created task for the first time.
1761 * This function will do some initial scheduler statistics housekeeping
1762 * that must be done for every newly created context, then puts the task
1763 * on the runqueue and wakes it.
1765 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1767 unsigned long flags
;
1770 rq
= task_rq_lock(p
, &flags
);
1771 BUG_ON(p
->state
!= TASK_RUNNING
);
1772 update_rq_clock(rq
);
1774 p
->prio
= effective_prio(p
);
1776 if (!p
->sched_class
->task_new
|| !current
->se
.on_rq
) {
1777 activate_task(rq
, p
, 0);
1780 * Let the scheduling class do new task startup
1781 * management (if any):
1783 p
->sched_class
->task_new(rq
, p
);
1784 inc_nr_running(p
, rq
);
1786 check_preempt_curr(rq
, p
);
1787 task_rq_unlock(rq
, &flags
);
1790 #ifdef CONFIG_PREEMPT_NOTIFIERS
1793 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
1794 * @notifier: notifier struct to register
1796 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1798 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1800 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1803 * preempt_notifier_unregister - no longer interested in preemption notifications
1804 * @notifier: notifier struct to unregister
1806 * This is safe to call from within a preemption notifier.
1808 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1810 hlist_del(¬ifier
->link
);
1812 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1814 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1816 struct preempt_notifier
*notifier
;
1817 struct hlist_node
*node
;
1819 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1820 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1824 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1825 struct task_struct
*next
)
1827 struct preempt_notifier
*notifier
;
1828 struct hlist_node
*node
;
1830 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1831 notifier
->ops
->sched_out(notifier
, next
);
1836 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1841 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1842 struct task_struct
*next
)
1849 * prepare_task_switch - prepare to switch tasks
1850 * @rq: the runqueue preparing to switch
1851 * @prev: the current task that is being switched out
1852 * @next: the task we are going to switch to.
1854 * This is called with the rq lock held and interrupts off. It must
1855 * be paired with a subsequent finish_task_switch after the context
1858 * prepare_task_switch sets up locking and calls architecture specific
1862 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1863 struct task_struct
*next
)
1865 fire_sched_out_preempt_notifiers(prev
, next
);
1866 prepare_lock_switch(rq
, next
);
1867 prepare_arch_switch(next
);
1871 * finish_task_switch - clean up after a task-switch
1872 * @rq: runqueue associated with task-switch
1873 * @prev: the thread we just switched away from.
1875 * finish_task_switch must be called after the context switch, paired
1876 * with a prepare_task_switch call before the context switch.
1877 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1878 * and do any other architecture-specific cleanup actions.
1880 * Note that we may have delayed dropping an mm in context_switch(). If
1881 * so, we finish that here outside of the runqueue lock. (Doing it
1882 * with the lock held can cause deadlocks; see schedule() for
1885 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1886 __releases(rq
->lock
)
1888 struct mm_struct
*mm
= rq
->prev_mm
;
1894 * A task struct has one reference for the use as "current".
1895 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1896 * schedule one last time. The schedule call will never return, and
1897 * the scheduled task must drop that reference.
1898 * The test for TASK_DEAD must occur while the runqueue locks are
1899 * still held, otherwise prev could be scheduled on another cpu, die
1900 * there before we look at prev->state, and then the reference would
1902 * Manfred Spraul <manfred@colorfullife.com>
1904 prev_state
= prev
->state
;
1905 finish_arch_switch(prev
);
1906 finish_lock_switch(rq
, prev
);
1907 fire_sched_in_preempt_notifiers(current
);
1910 if (unlikely(prev_state
== TASK_DEAD
)) {
1912 * Remove function-return probe instances associated with this
1913 * task and put them back on the free list.
1915 kprobe_flush_task(prev
);
1916 put_task_struct(prev
);
1921 * schedule_tail - first thing a freshly forked thread must call.
1922 * @prev: the thread we just switched away from.
1924 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1925 __releases(rq
->lock
)
1927 struct rq
*rq
= this_rq();
1929 finish_task_switch(rq
, prev
);
1930 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1931 /* In this case, finish_task_switch does not reenable preemption */
1934 if (current
->set_child_tid
)
1935 put_user(task_pid_vnr(current
), current
->set_child_tid
);
1939 * context_switch - switch to the new MM and the new
1940 * thread's register state.
1943 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1944 struct task_struct
*next
)
1946 struct mm_struct
*mm
, *oldmm
;
1948 prepare_task_switch(rq
, prev
, next
);
1950 oldmm
= prev
->active_mm
;
1952 * For paravirt, this is coupled with an exit in switch_to to
1953 * combine the page table reload and the switch backend into
1956 arch_enter_lazy_cpu_mode();
1958 if (unlikely(!mm
)) {
1959 next
->active_mm
= oldmm
;
1960 atomic_inc(&oldmm
->mm_count
);
1961 enter_lazy_tlb(oldmm
, next
);
1963 switch_mm(oldmm
, mm
, next
);
1965 if (unlikely(!prev
->mm
)) {
1966 prev
->active_mm
= NULL
;
1967 rq
->prev_mm
= oldmm
;
1970 * Since the runqueue lock will be released by the next
1971 * task (which is an invalid locking op but in the case
1972 * of the scheduler it's an obvious special-case), so we
1973 * do an early lockdep release here:
1975 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1976 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1979 /* Here we just switch the register state and the stack. */
1980 switch_to(prev
, next
, prev
);
1984 * this_rq must be evaluated again because prev may have moved
1985 * CPUs since it called schedule(), thus the 'rq' on its stack
1986 * frame will be invalid.
1988 finish_task_switch(this_rq(), prev
);
1992 * nr_running, nr_uninterruptible and nr_context_switches:
1994 * externally visible scheduler statistics: current number of runnable
1995 * threads, current number of uninterruptible-sleeping threads, total
1996 * number of context switches performed since bootup.
1998 unsigned long nr_running(void)
2000 unsigned long i
, sum
= 0;
2002 for_each_online_cpu(i
)
2003 sum
+= cpu_rq(i
)->nr_running
;
2008 unsigned long nr_uninterruptible(void)
2010 unsigned long i
, sum
= 0;
2012 for_each_possible_cpu(i
)
2013 sum
+= cpu_rq(i
)->nr_uninterruptible
;
2016 * Since we read the counters lockless, it might be slightly
2017 * inaccurate. Do not allow it to go below zero though:
2019 if (unlikely((long)sum
< 0))
2025 unsigned long long nr_context_switches(void)
2028 unsigned long long sum
= 0;
2030 for_each_possible_cpu(i
)
2031 sum
+= cpu_rq(i
)->nr_switches
;
2036 unsigned long nr_iowait(void)
2038 unsigned long i
, sum
= 0;
2040 for_each_possible_cpu(i
)
2041 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2046 unsigned long nr_active(void)
2048 unsigned long i
, running
= 0, uninterruptible
= 0;
2050 for_each_online_cpu(i
) {
2051 running
+= cpu_rq(i
)->nr_running
;
2052 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
2055 if (unlikely((long)uninterruptible
< 0))
2056 uninterruptible
= 0;
2058 return running
+ uninterruptible
;
2062 * Update rq->cpu_load[] statistics. This function is usually called every
2063 * scheduler tick (TICK_NSEC).
2065 static void update_cpu_load(struct rq
*this_rq
)
2067 unsigned long this_load
= this_rq
->load
.weight
;
2070 this_rq
->nr_load_updates
++;
2072 /* Update our load: */
2073 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2074 unsigned long old_load
, new_load
;
2076 /* scale is effectively 1 << i now, and >> i divides by scale */
2078 old_load
= this_rq
->cpu_load
[i
];
2079 new_load
= this_load
;
2081 * Round up the averaging division if load is increasing. This
2082 * prevents us from getting stuck on 9 if the load is 10, for
2085 if (new_load
> old_load
)
2086 new_load
+= scale
-1;
2087 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2094 * double_rq_lock - safely lock two runqueues
2096 * Note this does not disable interrupts like task_rq_lock,
2097 * you need to do so manually before calling.
2099 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
2100 __acquires(rq1
->lock
)
2101 __acquires(rq2
->lock
)
2103 BUG_ON(!irqs_disabled());
2105 spin_lock(&rq1
->lock
);
2106 __acquire(rq2
->lock
); /* Fake it out ;) */
2109 spin_lock(&rq1
->lock
);
2110 spin_lock(&rq2
->lock
);
2112 spin_lock(&rq2
->lock
);
2113 spin_lock(&rq1
->lock
);
2116 update_rq_clock(rq1
);
2117 update_rq_clock(rq2
);
2121 * double_rq_unlock - safely unlock two runqueues
2123 * Note this does not restore interrupts like task_rq_unlock,
2124 * you need to do so manually after calling.
2126 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2127 __releases(rq1
->lock
)
2128 __releases(rq2
->lock
)
2130 spin_unlock(&rq1
->lock
);
2132 spin_unlock(&rq2
->lock
);
2134 __release(rq2
->lock
);
2138 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2140 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2141 __releases(this_rq
->lock
)
2142 __acquires(busiest
->lock
)
2143 __acquires(this_rq
->lock
)
2145 if (unlikely(!irqs_disabled())) {
2146 /* printk() doesn't work good under rq->lock */
2147 spin_unlock(&this_rq
->lock
);
2150 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2151 if (busiest
< this_rq
) {
2152 spin_unlock(&this_rq
->lock
);
2153 spin_lock(&busiest
->lock
);
2154 spin_lock(&this_rq
->lock
);
2156 spin_lock(&busiest
->lock
);
2161 * If dest_cpu is allowed for this process, migrate the task to it.
2162 * This is accomplished by forcing the cpu_allowed mask to only
2163 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2164 * the cpu_allowed mask is restored.
2166 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2168 struct migration_req req
;
2169 unsigned long flags
;
2172 rq
= task_rq_lock(p
, &flags
);
2173 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2174 || unlikely(cpu_is_offline(dest_cpu
)))
2177 /* force the process onto the specified CPU */
2178 if (migrate_task(p
, dest_cpu
, &req
)) {
2179 /* Need to wait for migration thread (might exit: take ref). */
2180 struct task_struct
*mt
= rq
->migration_thread
;
2182 get_task_struct(mt
);
2183 task_rq_unlock(rq
, &flags
);
2184 wake_up_process(mt
);
2185 put_task_struct(mt
);
2186 wait_for_completion(&req
.done
);
2191 task_rq_unlock(rq
, &flags
);
2195 * sched_exec - execve() is a valuable balancing opportunity, because at
2196 * this point the task has the smallest effective memory and cache footprint.
2198 void sched_exec(void)
2200 int new_cpu
, this_cpu
= get_cpu();
2201 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2203 if (new_cpu
!= this_cpu
)
2204 sched_migrate_task(current
, new_cpu
);
2208 * pull_task - move a task from a remote runqueue to the local runqueue.
2209 * Both runqueues must be locked.
2211 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2212 struct rq
*this_rq
, int this_cpu
)
2214 deactivate_task(src_rq
, p
, 0);
2215 set_task_cpu(p
, this_cpu
);
2216 activate_task(this_rq
, p
, 0);
2218 * Note that idle threads have a prio of MAX_PRIO, for this test
2219 * to be always true for them.
2221 check_preempt_curr(this_rq
, p
);
2225 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2228 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2229 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2233 * We do not migrate tasks that are:
2234 * 1) running (obviously), or
2235 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2236 * 3) are cache-hot on their current CPU.
2238 if (!cpu_isset(this_cpu
, p
->cpus_allowed
)) {
2239 schedstat_inc(p
, se
.nr_failed_migrations_affine
);
2244 if (task_running(rq
, p
)) {
2245 schedstat_inc(p
, se
.nr_failed_migrations_running
);
2250 * Aggressive migration if:
2251 * 1) task is cache cold, or
2252 * 2) too many balance attempts have failed.
2255 if (!task_hot(p
, rq
->clock
, sd
) ||
2256 sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2257 #ifdef CONFIG_SCHEDSTATS
2258 if (task_hot(p
, rq
->clock
, sd
)) {
2259 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2260 schedstat_inc(p
, se
.nr_forced_migrations
);
2266 if (task_hot(p
, rq
->clock
, sd
)) {
2267 schedstat_inc(p
, se
.nr_failed_migrations_hot
);
2273 static unsigned long
2274 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2275 unsigned long max_load_move
, struct sched_domain
*sd
,
2276 enum cpu_idle_type idle
, int *all_pinned
,
2277 int *this_best_prio
, struct rq_iterator
*iterator
)
2279 int loops
= 0, pulled
= 0, pinned
= 0, skip_for_load
;
2280 struct task_struct
*p
;
2281 long rem_load_move
= max_load_move
;
2283 if (max_load_move
== 0)
2289 * Start the load-balancing iterator:
2291 p
= iterator
->start(iterator
->arg
);
2293 if (!p
|| loops
++ > sysctl_sched_nr_migrate
)
2296 * To help distribute high priority tasks across CPUs we don't
2297 * skip a task if it will be the highest priority task (i.e. smallest
2298 * prio value) on its new queue regardless of its load weight
2300 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2301 SCHED_LOAD_SCALE_FUZZ
;
2302 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2303 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2304 p
= iterator
->next(iterator
->arg
);
2308 pull_task(busiest
, p
, this_rq
, this_cpu
);
2310 rem_load_move
-= p
->se
.load
.weight
;
2313 * We only want to steal up to the prescribed amount of weighted load.
2315 if (rem_load_move
> 0) {
2316 if (p
->prio
< *this_best_prio
)
2317 *this_best_prio
= p
->prio
;
2318 p
= iterator
->next(iterator
->arg
);
2323 * Right now, this is one of only two places pull_task() is called,
2324 * so we can safely collect pull_task() stats here rather than
2325 * inside pull_task().
2327 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2330 *all_pinned
= pinned
;
2332 return max_load_move
- rem_load_move
;
2336 * move_tasks tries to move up to max_load_move weighted load from busiest to
2337 * this_rq, as part of a balancing operation within domain "sd".
2338 * Returns 1 if successful and 0 otherwise.
2340 * Called with both runqueues locked.
2342 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2343 unsigned long max_load_move
,
2344 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2347 const struct sched_class
*class = sched_class_highest
;
2348 unsigned long total_load_moved
= 0;
2349 int this_best_prio
= this_rq
->curr
->prio
;
2353 class->load_balance(this_rq
, this_cpu
, busiest
,
2354 max_load_move
- total_load_moved
,
2355 sd
, idle
, all_pinned
, &this_best_prio
);
2356 class = class->next
;
2357 } while (class && max_load_move
> total_load_moved
);
2359 return total_load_moved
> 0;
2363 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2364 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2365 struct rq_iterator
*iterator
)
2367 struct task_struct
*p
= iterator
->start(iterator
->arg
);
2371 if (can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2372 pull_task(busiest
, p
, this_rq
, this_cpu
);
2374 * Right now, this is only the second place pull_task()
2375 * is called, so we can safely collect pull_task()
2376 * stats here rather than inside pull_task().
2378 schedstat_inc(sd
, lb_gained
[idle
]);
2382 p
= iterator
->next(iterator
->arg
);
2389 * move_one_task tries to move exactly one task from busiest to this_rq, as
2390 * part of active balancing operations within "domain".
2391 * Returns 1 if successful and 0 otherwise.
2393 * Called with both runqueues locked.
2395 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2396 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2398 const struct sched_class
*class;
2400 for (class = sched_class_highest
; class; class = class->next
)
2401 if (class->move_one_task(this_rq
, this_cpu
, busiest
, sd
, idle
))
2408 * find_busiest_group finds and returns the busiest CPU group within the
2409 * domain. It calculates and returns the amount of weighted load which
2410 * should be moved to restore balance via the imbalance parameter.
2412 static struct sched_group
*
2413 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2414 unsigned long *imbalance
, enum cpu_idle_type idle
,
2415 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2417 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2418 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2419 unsigned long max_pull
;
2420 unsigned long busiest_load_per_task
, busiest_nr_running
;
2421 unsigned long this_load_per_task
, this_nr_running
;
2422 int load_idx
, group_imb
= 0;
2423 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2424 int power_savings_balance
= 1;
2425 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2426 unsigned long min_nr_running
= ULONG_MAX
;
2427 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2430 max_load
= this_load
= total_load
= total_pwr
= 0;
2431 busiest_load_per_task
= busiest_nr_running
= 0;
2432 this_load_per_task
= this_nr_running
= 0;
2433 if (idle
== CPU_NOT_IDLE
)
2434 load_idx
= sd
->busy_idx
;
2435 else if (idle
== CPU_NEWLY_IDLE
)
2436 load_idx
= sd
->newidle_idx
;
2438 load_idx
= sd
->idle_idx
;
2441 unsigned long load
, group_capacity
, max_cpu_load
, min_cpu_load
;
2444 int __group_imb
= 0;
2445 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2446 unsigned long sum_nr_running
, sum_weighted_load
;
2448 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2451 balance_cpu
= first_cpu(group
->cpumask
);
2453 /* Tally up the load of all CPUs in the group */
2454 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2456 min_cpu_load
= ~0UL;
2458 for_each_cpu_mask(i
, group
->cpumask
) {
2461 if (!cpu_isset(i
, *cpus
))
2466 if (*sd_idle
&& rq
->nr_running
)
2469 /* Bias balancing toward cpus of our domain */
2471 if (idle_cpu(i
) && !first_idle_cpu
) {
2476 load
= target_load(i
, load_idx
);
2478 load
= source_load(i
, load_idx
);
2479 if (load
> max_cpu_load
)
2480 max_cpu_load
= load
;
2481 if (min_cpu_load
> load
)
2482 min_cpu_load
= load
;
2486 sum_nr_running
+= rq
->nr_running
;
2487 sum_weighted_load
+= weighted_cpuload(i
);
2491 * First idle cpu or the first cpu(busiest) in this sched group
2492 * is eligible for doing load balancing at this and above
2493 * domains. In the newly idle case, we will allow all the cpu's
2494 * to do the newly idle load balance.
2496 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2497 balance_cpu
!= this_cpu
&& balance
) {
2502 total_load
+= avg_load
;
2503 total_pwr
+= group
->__cpu_power
;
2505 /* Adjust by relative CPU power of the group */
2506 avg_load
= sg_div_cpu_power(group
,
2507 avg_load
* SCHED_LOAD_SCALE
);
2509 if ((max_cpu_load
- min_cpu_load
) > SCHED_LOAD_SCALE
)
2512 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2515 this_load
= avg_load
;
2517 this_nr_running
= sum_nr_running
;
2518 this_load_per_task
= sum_weighted_load
;
2519 } else if (avg_load
> max_load
&&
2520 (sum_nr_running
> group_capacity
|| __group_imb
)) {
2521 max_load
= avg_load
;
2523 busiest_nr_running
= sum_nr_running
;
2524 busiest_load_per_task
= sum_weighted_load
;
2525 group_imb
= __group_imb
;
2528 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2530 * Busy processors will not participate in power savings
2533 if (idle
== CPU_NOT_IDLE
||
2534 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2538 * If the local group is idle or completely loaded
2539 * no need to do power savings balance at this domain
2541 if (local_group
&& (this_nr_running
>= group_capacity
||
2543 power_savings_balance
= 0;
2546 * If a group is already running at full capacity or idle,
2547 * don't include that group in power savings calculations
2549 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2554 * Calculate the group which has the least non-idle load.
2555 * This is the group from where we need to pick up the load
2558 if ((sum_nr_running
< min_nr_running
) ||
2559 (sum_nr_running
== min_nr_running
&&
2560 first_cpu(group
->cpumask
) <
2561 first_cpu(group_min
->cpumask
))) {
2563 min_nr_running
= sum_nr_running
;
2564 min_load_per_task
= sum_weighted_load
/
2569 * Calculate the group which is almost near its
2570 * capacity but still has some space to pick up some load
2571 * from other group and save more power
2573 if (sum_nr_running
<= group_capacity
- 1) {
2574 if (sum_nr_running
> leader_nr_running
||
2575 (sum_nr_running
== leader_nr_running
&&
2576 first_cpu(group
->cpumask
) >
2577 first_cpu(group_leader
->cpumask
))) {
2578 group_leader
= group
;
2579 leader_nr_running
= sum_nr_running
;
2584 group
= group
->next
;
2585 } while (group
!= sd
->groups
);
2587 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2590 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2592 if (this_load
>= avg_load
||
2593 100*max_load
<= sd
->imbalance_pct
*this_load
)
2596 busiest_load_per_task
/= busiest_nr_running
;
2598 busiest_load_per_task
= min(busiest_load_per_task
, avg_load
);
2601 * We're trying to get all the cpus to the average_load, so we don't
2602 * want to push ourselves above the average load, nor do we wish to
2603 * reduce the max loaded cpu below the average load, as either of these
2604 * actions would just result in more rebalancing later, and ping-pong
2605 * tasks around. Thus we look for the minimum possible imbalance.
2606 * Negative imbalances (*we* are more loaded than anyone else) will
2607 * be counted as no imbalance for these purposes -- we can't fix that
2608 * by pulling tasks to us. Be careful of negative numbers as they'll
2609 * appear as very large values with unsigned longs.
2611 if (max_load
<= busiest_load_per_task
)
2615 * In the presence of smp nice balancing, certain scenarios can have
2616 * max load less than avg load(as we skip the groups at or below
2617 * its cpu_power, while calculating max_load..)
2619 if (max_load
< avg_load
) {
2621 goto small_imbalance
;
2624 /* Don't want to pull so many tasks that a group would go idle */
2625 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2627 /* How much load to actually move to equalise the imbalance */
2628 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2629 (avg_load
- this_load
) * this->__cpu_power
)
2633 * if *imbalance is less than the average load per runnable task
2634 * there is no gaurantee that any tasks will be moved so we'll have
2635 * a think about bumping its value to force at least one task to be
2638 if (*imbalance
< busiest_load_per_task
) {
2639 unsigned long tmp
, pwr_now
, pwr_move
;
2643 pwr_move
= pwr_now
= 0;
2645 if (this_nr_running
) {
2646 this_load_per_task
/= this_nr_running
;
2647 if (busiest_load_per_task
> this_load_per_task
)
2650 this_load_per_task
= SCHED_LOAD_SCALE
;
2652 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
2653 busiest_load_per_task
* imbn
) {
2654 *imbalance
= busiest_load_per_task
;
2659 * OK, we don't have enough imbalance to justify moving tasks,
2660 * however we may be able to increase total CPU power used by
2664 pwr_now
+= busiest
->__cpu_power
*
2665 min(busiest_load_per_task
, max_load
);
2666 pwr_now
+= this->__cpu_power
*
2667 min(this_load_per_task
, this_load
);
2668 pwr_now
/= SCHED_LOAD_SCALE
;
2670 /* Amount of load we'd subtract */
2671 tmp
= sg_div_cpu_power(busiest
,
2672 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2674 pwr_move
+= busiest
->__cpu_power
*
2675 min(busiest_load_per_task
, max_load
- tmp
);
2677 /* Amount of load we'd add */
2678 if (max_load
* busiest
->__cpu_power
<
2679 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2680 tmp
= sg_div_cpu_power(this,
2681 max_load
* busiest
->__cpu_power
);
2683 tmp
= sg_div_cpu_power(this,
2684 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2685 pwr_move
+= this->__cpu_power
*
2686 min(this_load_per_task
, this_load
+ tmp
);
2687 pwr_move
/= SCHED_LOAD_SCALE
;
2689 /* Move if we gain throughput */
2690 if (pwr_move
> pwr_now
)
2691 *imbalance
= busiest_load_per_task
;
2697 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2698 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2701 if (this == group_leader
&& group_leader
!= group_min
) {
2702 *imbalance
= min_load_per_task
;
2712 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2715 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
2716 unsigned long imbalance
, cpumask_t
*cpus
)
2718 struct rq
*busiest
= NULL
, *rq
;
2719 unsigned long max_load
= 0;
2722 for_each_cpu_mask(i
, group
->cpumask
) {
2725 if (!cpu_isset(i
, *cpus
))
2729 wl
= weighted_cpuload(i
);
2731 if (rq
->nr_running
== 1 && wl
> imbalance
)
2734 if (wl
> max_load
) {
2744 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2745 * so long as it is large enough.
2747 #define MAX_PINNED_INTERVAL 512
2750 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2751 * tasks if there is an imbalance.
2753 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2754 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2757 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2758 struct sched_group
*group
;
2759 unsigned long imbalance
;
2761 cpumask_t cpus
= CPU_MASK_ALL
;
2762 unsigned long flags
;
2765 * When power savings policy is enabled for the parent domain, idle
2766 * sibling can pick up load irrespective of busy siblings. In this case,
2767 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2768 * portraying it as CPU_NOT_IDLE.
2770 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2771 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2774 schedstat_inc(sd
, lb_count
[idle
]);
2777 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2784 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2788 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2790 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2794 BUG_ON(busiest
== this_rq
);
2796 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2799 if (busiest
->nr_running
> 1) {
2801 * Attempt to move tasks. If find_busiest_group has found
2802 * an imbalance but busiest->nr_running <= 1, the group is
2803 * still unbalanced. ld_moved simply stays zero, so it is
2804 * correctly treated as an imbalance.
2806 local_irq_save(flags
);
2807 double_rq_lock(this_rq
, busiest
);
2808 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2809 imbalance
, sd
, idle
, &all_pinned
);
2810 double_rq_unlock(this_rq
, busiest
);
2811 local_irq_restore(flags
);
2814 * some other cpu did the load balance for us.
2816 if (ld_moved
&& this_cpu
!= smp_processor_id())
2817 resched_cpu(this_cpu
);
2819 /* All tasks on this runqueue were pinned by CPU affinity */
2820 if (unlikely(all_pinned
)) {
2821 cpu_clear(cpu_of(busiest
), cpus
);
2822 if (!cpus_empty(cpus
))
2829 schedstat_inc(sd
, lb_failed
[idle
]);
2830 sd
->nr_balance_failed
++;
2832 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2834 spin_lock_irqsave(&busiest
->lock
, flags
);
2836 /* don't kick the migration_thread, if the curr
2837 * task on busiest cpu can't be moved to this_cpu
2839 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2840 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2842 goto out_one_pinned
;
2845 if (!busiest
->active_balance
) {
2846 busiest
->active_balance
= 1;
2847 busiest
->push_cpu
= this_cpu
;
2850 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2852 wake_up_process(busiest
->migration_thread
);
2855 * We've kicked active balancing, reset the failure
2858 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2861 sd
->nr_balance_failed
= 0;
2863 if (likely(!active_balance
)) {
2864 /* We were unbalanced, so reset the balancing interval */
2865 sd
->balance_interval
= sd
->min_interval
;
2868 * If we've begun active balancing, start to back off. This
2869 * case may not be covered by the all_pinned logic if there
2870 * is only 1 task on the busy runqueue (because we don't call
2873 if (sd
->balance_interval
< sd
->max_interval
)
2874 sd
->balance_interval
*= 2;
2877 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2878 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2883 schedstat_inc(sd
, lb_balanced
[idle
]);
2885 sd
->nr_balance_failed
= 0;
2888 /* tune up the balancing interval */
2889 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2890 (sd
->balance_interval
< sd
->max_interval
))
2891 sd
->balance_interval
*= 2;
2893 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2894 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2900 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2901 * tasks if there is an imbalance.
2903 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2904 * this_rq is locked.
2907 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2909 struct sched_group
*group
;
2910 struct rq
*busiest
= NULL
;
2911 unsigned long imbalance
;
2915 cpumask_t cpus
= CPU_MASK_ALL
;
2918 * When power savings policy is enabled for the parent domain, idle
2919 * sibling can pick up load irrespective of busy siblings. In this case,
2920 * let the state of idle sibling percolate up as IDLE, instead of
2921 * portraying it as CPU_NOT_IDLE.
2923 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2924 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2927 schedstat_inc(sd
, lb_count
[CPU_NEWLY_IDLE
]);
2929 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
2930 &sd_idle
, &cpus
, NULL
);
2932 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
2936 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
2939 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
2943 BUG_ON(busiest
== this_rq
);
2945 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
2948 if (busiest
->nr_running
> 1) {
2949 /* Attempt to move tasks */
2950 double_lock_balance(this_rq
, busiest
);
2951 /* this_rq->clock is already updated */
2952 update_rq_clock(busiest
);
2953 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2954 imbalance
, sd
, CPU_NEWLY_IDLE
,
2956 spin_unlock(&busiest
->lock
);
2958 if (unlikely(all_pinned
)) {
2959 cpu_clear(cpu_of(busiest
), cpus
);
2960 if (!cpus_empty(cpus
))
2966 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
2967 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2968 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2971 sd
->nr_balance_failed
= 0;
2976 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
2977 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2978 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2980 sd
->nr_balance_failed
= 0;
2986 * idle_balance is called by schedule() if this_cpu is about to become
2987 * idle. Attempts to pull tasks from other CPUs.
2989 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2991 struct sched_domain
*sd
;
2992 int pulled_task
= -1;
2993 unsigned long next_balance
= jiffies
+ HZ
;
2995 for_each_domain(this_cpu
, sd
) {
2996 unsigned long interval
;
2998 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3001 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
3002 /* If we've pulled tasks over stop searching: */
3003 pulled_task
= load_balance_newidle(this_cpu
,
3006 interval
= msecs_to_jiffies(sd
->balance_interval
);
3007 if (time_after(next_balance
, sd
->last_balance
+ interval
))
3008 next_balance
= sd
->last_balance
+ interval
;
3012 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
3014 * We are going idle. next_balance may be set based on
3015 * a busy processor. So reset next_balance.
3017 this_rq
->next_balance
= next_balance
;
3022 * active_load_balance is run by migration threads. It pushes running tasks
3023 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
3024 * running on each physical CPU where possible, and avoids physical /
3025 * logical imbalances.
3027 * Called with busiest_rq locked.
3029 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
3031 int target_cpu
= busiest_rq
->push_cpu
;
3032 struct sched_domain
*sd
;
3033 struct rq
*target_rq
;
3035 /* Is there any task to move? */
3036 if (busiest_rq
->nr_running
<= 1)
3039 target_rq
= cpu_rq(target_cpu
);
3042 * This condition is "impossible", if it occurs
3043 * we need to fix it. Originally reported by
3044 * Bjorn Helgaas on a 128-cpu setup.
3046 BUG_ON(busiest_rq
== target_rq
);
3048 /* move a task from busiest_rq to target_rq */
3049 double_lock_balance(busiest_rq
, target_rq
);
3050 update_rq_clock(busiest_rq
);
3051 update_rq_clock(target_rq
);
3053 /* Search for an sd spanning us and the target CPU. */
3054 for_each_domain(target_cpu
, sd
) {
3055 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
3056 cpu_isset(busiest_cpu
, sd
->span
))
3061 schedstat_inc(sd
, alb_count
);
3063 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
3065 schedstat_inc(sd
, alb_pushed
);
3067 schedstat_inc(sd
, alb_failed
);
3069 spin_unlock(&target_rq
->lock
);
3074 atomic_t load_balancer
;
3076 } nohz ____cacheline_aligned
= {
3077 .load_balancer
= ATOMIC_INIT(-1),
3078 .cpu_mask
= CPU_MASK_NONE
,
3082 * This routine will try to nominate the ilb (idle load balancing)
3083 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3084 * load balancing on behalf of all those cpus. If all the cpus in the system
3085 * go into this tickless mode, then there will be no ilb owner (as there is
3086 * no need for one) and all the cpus will sleep till the next wakeup event
3089 * For the ilb owner, tick is not stopped. And this tick will be used
3090 * for idle load balancing. ilb owner will still be part of
3093 * While stopping the tick, this cpu will become the ilb owner if there
3094 * is no other owner. And will be the owner till that cpu becomes busy
3095 * or if all cpus in the system stop their ticks at which point
3096 * there is no need for ilb owner.
3098 * When the ilb owner becomes busy, it nominates another owner, during the
3099 * next busy scheduler_tick()
3101 int select_nohz_load_balancer(int stop_tick
)
3103 int cpu
= smp_processor_id();
3106 cpu_set(cpu
, nohz
.cpu_mask
);
3107 cpu_rq(cpu
)->in_nohz_recently
= 1;
3110 * If we are going offline and still the leader, give up!
3112 if (cpu_is_offline(cpu
) &&
3113 atomic_read(&nohz
.load_balancer
) == cpu
) {
3114 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3119 /* time for ilb owner also to sleep */
3120 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3121 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3122 atomic_set(&nohz
.load_balancer
, -1);
3126 if (atomic_read(&nohz
.load_balancer
) == -1) {
3127 /* make me the ilb owner */
3128 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
3130 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
3133 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
3136 cpu_clear(cpu
, nohz
.cpu_mask
);
3138 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3139 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3146 static DEFINE_SPINLOCK(balancing
);
3149 * It checks each scheduling domain to see if it is due to be balanced,
3150 * and initiates a balancing operation if so.
3152 * Balancing parameters are set up in arch_init_sched_domains.
3154 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3157 struct rq
*rq
= cpu_rq(cpu
);
3158 unsigned long interval
;
3159 struct sched_domain
*sd
;
3160 /* Earliest time when we have to do rebalance again */
3161 unsigned long next_balance
= jiffies
+ 60*HZ
;
3162 int update_next_balance
= 0;
3164 for_each_domain(cpu
, sd
) {
3165 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3168 interval
= sd
->balance_interval
;
3169 if (idle
!= CPU_IDLE
)
3170 interval
*= sd
->busy_factor
;
3172 /* scale ms to jiffies */
3173 interval
= msecs_to_jiffies(interval
);
3174 if (unlikely(!interval
))
3176 if (interval
> HZ
*NR_CPUS
/10)
3177 interval
= HZ
*NR_CPUS
/10;
3180 if (sd
->flags
& SD_SERIALIZE
) {
3181 if (!spin_trylock(&balancing
))
3185 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3186 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3188 * We've pulled tasks over so either we're no
3189 * longer idle, or one of our SMT siblings is
3192 idle
= CPU_NOT_IDLE
;
3194 sd
->last_balance
= jiffies
;
3196 if (sd
->flags
& SD_SERIALIZE
)
3197 spin_unlock(&balancing
);
3199 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3200 next_balance
= sd
->last_balance
+ interval
;
3201 update_next_balance
= 1;
3205 * Stop the load balance at this level. There is another
3206 * CPU in our sched group which is doing load balancing more
3214 * next_balance will be updated only when there is a need.
3215 * When the cpu is attached to null domain for ex, it will not be
3218 if (likely(update_next_balance
))
3219 rq
->next_balance
= next_balance
;
3223 * run_rebalance_domains is triggered when needed from the scheduler tick.
3224 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3225 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3227 static void run_rebalance_domains(struct softirq_action
*h
)
3229 int this_cpu
= smp_processor_id();
3230 struct rq
*this_rq
= cpu_rq(this_cpu
);
3231 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3232 CPU_IDLE
: CPU_NOT_IDLE
;
3234 rebalance_domains(this_cpu
, idle
);
3238 * If this cpu is the owner for idle load balancing, then do the
3239 * balancing on behalf of the other idle cpus whose ticks are
3242 if (this_rq
->idle_at_tick
&&
3243 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3244 cpumask_t cpus
= nohz
.cpu_mask
;
3248 cpu_clear(this_cpu
, cpus
);
3249 for_each_cpu_mask(balance_cpu
, cpus
) {
3251 * If this cpu gets work to do, stop the load balancing
3252 * work being done for other cpus. Next load
3253 * balancing owner will pick it up.
3258 rebalance_domains(balance_cpu
, CPU_IDLE
);
3260 rq
= cpu_rq(balance_cpu
);
3261 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3262 this_rq
->next_balance
= rq
->next_balance
;
3269 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3271 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3272 * idle load balancing owner or decide to stop the periodic load balancing,
3273 * if the whole system is idle.
3275 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3279 * If we were in the nohz mode recently and busy at the current
3280 * scheduler tick, then check if we need to nominate new idle
3283 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3284 rq
->in_nohz_recently
= 0;
3286 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3287 cpu_clear(cpu
, nohz
.cpu_mask
);
3288 atomic_set(&nohz
.load_balancer
, -1);
3291 if (atomic_read(&nohz
.load_balancer
) == -1) {
3293 * simple selection for now: Nominate the
3294 * first cpu in the nohz list to be the next
3297 * TBD: Traverse the sched domains and nominate
3298 * the nearest cpu in the nohz.cpu_mask.
3300 int ilb
= first_cpu(nohz
.cpu_mask
);
3308 * If this cpu is idle and doing idle load balancing for all the
3309 * cpus with ticks stopped, is it time for that to stop?
3311 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3312 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3318 * If this cpu is idle and the idle load balancing is done by
3319 * someone else, then no need raise the SCHED_SOFTIRQ
3321 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3322 cpu_isset(cpu
, nohz
.cpu_mask
))
3325 if (time_after_eq(jiffies
, rq
->next_balance
))
3326 raise_softirq(SCHED_SOFTIRQ
);
3329 #else /* CONFIG_SMP */
3332 * on UP we do not need to balance between CPUs:
3334 static inline void idle_balance(int cpu
, struct rq
*rq
)
3340 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3342 EXPORT_PER_CPU_SYMBOL(kstat
);
3345 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3346 * that have not yet been banked in case the task is currently running.
3348 unsigned long long task_sched_runtime(struct task_struct
*p
)
3350 unsigned long flags
;
3354 rq
= task_rq_lock(p
, &flags
);
3355 ns
= p
->se
.sum_exec_runtime
;
3356 if (task_current(rq
, p
)) {
3357 update_rq_clock(rq
);
3358 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3359 if ((s64
)delta_exec
> 0)
3362 task_rq_unlock(rq
, &flags
);
3368 * Account user cpu time to a process.
3369 * @p: the process that the cpu time gets accounted to
3370 * @cputime: the cpu time spent in user space since the last update
3372 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3374 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3377 p
->utime
= cputime_add(p
->utime
, cputime
);
3379 /* Add user time to cpustat. */
3380 tmp
= cputime_to_cputime64(cputime
);
3381 if (TASK_NICE(p
) > 0)
3382 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3384 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3388 * Account guest cpu time to a process.
3389 * @p: the process that the cpu time gets accounted to
3390 * @cputime: the cpu time spent in virtual machine since the last update
3392 static void account_guest_time(struct task_struct
*p
, cputime_t cputime
)
3395 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3397 tmp
= cputime_to_cputime64(cputime
);
3399 p
->utime
= cputime_add(p
->utime
, cputime
);
3400 p
->gtime
= cputime_add(p
->gtime
, cputime
);
3402 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3403 cpustat
->guest
= cputime64_add(cpustat
->guest
, tmp
);
3407 * Account scaled user cpu time to a process.
3408 * @p: the process that the cpu time gets accounted to
3409 * @cputime: the cpu time spent in user space since the last update
3411 void account_user_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3413 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime
);
3417 * Account system cpu time to a process.
3418 * @p: the process that the cpu time gets accounted to
3419 * @hardirq_offset: the offset to subtract from hardirq_count()
3420 * @cputime: the cpu time spent in kernel space since the last update
3422 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3425 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3426 struct rq
*rq
= this_rq();
3429 if ((p
->flags
& PF_VCPU
) && (irq_count() - hardirq_offset
== 0))
3430 return account_guest_time(p
, cputime
);
3432 p
->stime
= cputime_add(p
->stime
, cputime
);
3434 /* Add system time to cpustat. */
3435 tmp
= cputime_to_cputime64(cputime
);
3436 if (hardirq_count() - hardirq_offset
)
3437 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3438 else if (softirq_count())
3439 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3440 else if (p
!= rq
->idle
)
3441 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3442 else if (atomic_read(&rq
->nr_iowait
) > 0)
3443 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3445 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3446 /* Account for system time used */
3447 acct_update_integrals(p
);
3451 * Account scaled system cpu time to a process.
3452 * @p: the process that the cpu time gets accounted to
3453 * @hardirq_offset: the offset to subtract from hardirq_count()
3454 * @cputime: the cpu time spent in kernel space since the last update
3456 void account_system_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3458 p
->stimescaled
= cputime_add(p
->stimescaled
, cputime
);
3462 * Account for involuntary wait time.
3463 * @p: the process from which the cpu time has been stolen
3464 * @steal: the cpu time spent in involuntary wait
3466 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3468 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3469 cputime64_t tmp
= cputime_to_cputime64(steal
);
3470 struct rq
*rq
= this_rq();
3472 if (p
== rq
->idle
) {
3473 p
->stime
= cputime_add(p
->stime
, steal
);
3474 if (atomic_read(&rq
->nr_iowait
) > 0)
3475 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3477 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3479 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3483 * This function gets called by the timer code, with HZ frequency.
3484 * We call it with interrupts disabled.
3486 * It also gets called by the fork code, when changing the parent's
3489 void scheduler_tick(void)
3491 int cpu
= smp_processor_id();
3492 struct rq
*rq
= cpu_rq(cpu
);
3493 struct task_struct
*curr
= rq
->curr
;
3494 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3496 spin_lock(&rq
->lock
);
3497 __update_rq_clock(rq
);
3499 * Let rq->clock advance by at least TICK_NSEC:
3501 if (unlikely(rq
->clock
< next_tick
))
3502 rq
->clock
= next_tick
;
3503 rq
->tick_timestamp
= rq
->clock
;
3504 update_cpu_load(rq
);
3505 if (curr
!= rq
->idle
) /* FIXME: needed? */
3506 curr
->sched_class
->task_tick(rq
, curr
);
3507 spin_unlock(&rq
->lock
);
3510 rq
->idle_at_tick
= idle_cpu(cpu
);
3511 trigger_load_balance(rq
, cpu
);
3515 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3517 void fastcall
add_preempt_count(int val
)
3522 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3524 preempt_count() += val
;
3526 * Spinlock count overflowing soon?
3528 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3531 EXPORT_SYMBOL(add_preempt_count
);
3533 void fastcall
sub_preempt_count(int val
)
3538 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3541 * Is the spinlock portion underflowing?
3543 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3544 !(preempt_count() & PREEMPT_MASK
)))
3547 preempt_count() -= val
;
3549 EXPORT_SYMBOL(sub_preempt_count
);
3554 * Print scheduling while atomic bug:
3556 static noinline
void __schedule_bug(struct task_struct
*prev
)
3558 struct pt_regs
*regs
= get_irq_regs();
3560 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3561 prev
->comm
, prev
->pid
, preempt_count());
3563 debug_show_held_locks(prev
);
3564 if (irqs_disabled())
3565 print_irqtrace_events(prev
);
3574 * Various schedule()-time debugging checks and statistics:
3576 static inline void schedule_debug(struct task_struct
*prev
)
3579 * Test if we are atomic. Since do_exit() needs to call into
3580 * schedule() atomically, we ignore that path for now.
3581 * Otherwise, whine if we are scheduling when we should not be.
3583 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3584 __schedule_bug(prev
);
3586 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3588 schedstat_inc(this_rq(), sched_count
);
3589 #ifdef CONFIG_SCHEDSTATS
3590 if (unlikely(prev
->lock_depth
>= 0)) {
3591 schedstat_inc(this_rq(), bkl_count
);
3592 schedstat_inc(prev
, sched_info
.bkl_count
);
3598 * Pick up the highest-prio task:
3600 static inline struct task_struct
*
3601 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3603 const struct sched_class
*class;
3604 struct task_struct
*p
;
3607 * Optimization: we know that if all tasks are in
3608 * the fair class we can call that function directly:
3610 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3611 p
= fair_sched_class
.pick_next_task(rq
);
3616 class = sched_class_highest
;
3618 p
= class->pick_next_task(rq
);
3622 * Will never be NULL as the idle class always
3623 * returns a non-NULL p:
3625 class = class->next
;
3630 * schedule() is the main scheduler function.
3632 asmlinkage
void __sched
schedule(void)
3634 struct task_struct
*prev
, *next
;
3641 cpu
= smp_processor_id();
3645 switch_count
= &prev
->nivcsw
;
3647 release_kernel_lock(prev
);
3648 need_resched_nonpreemptible
:
3650 schedule_debug(prev
);
3653 * Do the rq-clock update outside the rq lock:
3655 local_irq_disable();
3656 __update_rq_clock(rq
);
3657 spin_lock(&rq
->lock
);
3658 clear_tsk_need_resched(prev
);
3660 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3661 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3662 unlikely(signal_pending(prev
)))) {
3663 prev
->state
= TASK_RUNNING
;
3665 deactivate_task(rq
, prev
, 1);
3667 switch_count
= &prev
->nvcsw
;
3670 if (unlikely(!rq
->nr_running
))
3671 idle_balance(cpu
, rq
);
3673 prev
->sched_class
->put_prev_task(rq
, prev
);
3674 next
= pick_next_task(rq
, prev
);
3676 sched_info_switch(prev
, next
);
3678 if (likely(prev
!= next
)) {
3683 context_switch(rq
, prev
, next
); /* unlocks the rq */
3685 spin_unlock_irq(&rq
->lock
);
3687 if (unlikely(reacquire_kernel_lock(current
) < 0)) {
3688 cpu
= smp_processor_id();
3690 goto need_resched_nonpreemptible
;
3692 preempt_enable_no_resched();
3693 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3696 EXPORT_SYMBOL(schedule
);
3698 #ifdef CONFIG_PREEMPT
3700 * this is the entry point to schedule() from in-kernel preemption
3701 * off of preempt_enable. Kernel preemptions off return from interrupt
3702 * occur there and call schedule directly.
3704 asmlinkage
void __sched
preempt_schedule(void)
3706 struct thread_info
*ti
= current_thread_info();
3707 #ifdef CONFIG_PREEMPT_BKL
3708 struct task_struct
*task
= current
;
3709 int saved_lock_depth
;
3712 * If there is a non-zero preempt_count or interrupts are disabled,
3713 * we do not want to preempt the current task. Just return..
3715 if (likely(ti
->preempt_count
|| irqs_disabled()))
3719 add_preempt_count(PREEMPT_ACTIVE
);
3722 * We keep the big kernel semaphore locked, but we
3723 * clear ->lock_depth so that schedule() doesnt
3724 * auto-release the semaphore:
3726 #ifdef CONFIG_PREEMPT_BKL
3727 saved_lock_depth
= task
->lock_depth
;
3728 task
->lock_depth
= -1;
3731 #ifdef CONFIG_PREEMPT_BKL
3732 task
->lock_depth
= saved_lock_depth
;
3734 sub_preempt_count(PREEMPT_ACTIVE
);
3737 * Check again in case we missed a preemption opportunity
3738 * between schedule and now.
3741 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
3743 EXPORT_SYMBOL(preempt_schedule
);
3746 * this is the entry point to schedule() from kernel preemption
3747 * off of irq context.
3748 * Note, that this is called and return with irqs disabled. This will
3749 * protect us against recursive calling from irq.
3751 asmlinkage
void __sched
preempt_schedule_irq(void)
3753 struct thread_info
*ti
= current_thread_info();
3754 #ifdef CONFIG_PREEMPT_BKL
3755 struct task_struct
*task
= current
;
3756 int saved_lock_depth
;
3758 /* Catch callers which need to be fixed */
3759 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3762 add_preempt_count(PREEMPT_ACTIVE
);
3765 * We keep the big kernel semaphore locked, but we
3766 * clear ->lock_depth so that schedule() doesnt
3767 * auto-release the semaphore:
3769 #ifdef CONFIG_PREEMPT_BKL
3770 saved_lock_depth
= task
->lock_depth
;
3771 task
->lock_depth
= -1;
3775 local_irq_disable();
3776 #ifdef CONFIG_PREEMPT_BKL
3777 task
->lock_depth
= saved_lock_depth
;
3779 sub_preempt_count(PREEMPT_ACTIVE
);
3782 * Check again in case we missed a preemption opportunity
3783 * between schedule and now.
3786 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
3789 #endif /* CONFIG_PREEMPT */
3791 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3794 return try_to_wake_up(curr
->private, mode
, sync
);
3796 EXPORT_SYMBOL(default_wake_function
);
3799 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3800 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3801 * number) then we wake all the non-exclusive tasks and one exclusive task.
3803 * There are circumstances in which we can try to wake a task which has already
3804 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3805 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3807 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3808 int nr_exclusive
, int sync
, void *key
)
3810 wait_queue_t
*curr
, *next
;
3812 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3813 unsigned flags
= curr
->flags
;
3815 if (curr
->func(curr
, mode
, sync
, key
) &&
3816 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3822 * __wake_up - wake up threads blocked on a waitqueue.
3824 * @mode: which threads
3825 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3826 * @key: is directly passed to the wakeup function
3828 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3829 int nr_exclusive
, void *key
)
3831 unsigned long flags
;
3833 spin_lock_irqsave(&q
->lock
, flags
);
3834 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3835 spin_unlock_irqrestore(&q
->lock
, flags
);
3837 EXPORT_SYMBOL(__wake_up
);
3840 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3842 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3844 __wake_up_common(q
, mode
, 1, 0, NULL
);
3848 * __wake_up_sync - wake up threads blocked on a waitqueue.
3850 * @mode: which threads
3851 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3853 * The sync wakeup differs that the waker knows that it will schedule
3854 * away soon, so while the target thread will be woken up, it will not
3855 * be migrated to another CPU - ie. the two threads are 'synchronized'
3856 * with each other. This can prevent needless bouncing between CPUs.
3858 * On UP it can prevent extra preemption.
3861 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3863 unsigned long flags
;
3869 if (unlikely(!nr_exclusive
))
3872 spin_lock_irqsave(&q
->lock
, flags
);
3873 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3874 spin_unlock_irqrestore(&q
->lock
, flags
);
3876 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3878 void complete(struct completion
*x
)
3880 unsigned long flags
;
3882 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3884 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3886 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3888 EXPORT_SYMBOL(complete
);
3890 void complete_all(struct completion
*x
)
3892 unsigned long flags
;
3894 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3895 x
->done
+= UINT_MAX
/2;
3896 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3898 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3900 EXPORT_SYMBOL(complete_all
);
3902 static inline long __sched
3903 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
3906 DECLARE_WAITQUEUE(wait
, current
);
3908 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3909 __add_wait_queue_tail(&x
->wait
, &wait
);
3911 if (state
== TASK_INTERRUPTIBLE
&&
3912 signal_pending(current
)) {
3913 __remove_wait_queue(&x
->wait
, &wait
);
3914 return -ERESTARTSYS
;
3916 __set_current_state(state
);
3917 spin_unlock_irq(&x
->wait
.lock
);
3918 timeout
= schedule_timeout(timeout
);
3919 spin_lock_irq(&x
->wait
.lock
);
3921 __remove_wait_queue(&x
->wait
, &wait
);
3925 __remove_wait_queue(&x
->wait
, &wait
);
3932 wait_for_common(struct completion
*x
, long timeout
, int state
)
3936 spin_lock_irq(&x
->wait
.lock
);
3937 timeout
= do_wait_for_common(x
, timeout
, state
);
3938 spin_unlock_irq(&x
->wait
.lock
);
3942 void __sched
wait_for_completion(struct completion
*x
)
3944 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3946 EXPORT_SYMBOL(wait_for_completion
);
3948 unsigned long __sched
3949 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3951 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3953 EXPORT_SYMBOL(wait_for_completion_timeout
);
3955 int __sched
wait_for_completion_interruptible(struct completion
*x
)
3957 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
3958 if (t
== -ERESTARTSYS
)
3962 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3964 unsigned long __sched
3965 wait_for_completion_interruptible_timeout(struct completion
*x
,
3966 unsigned long timeout
)
3968 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
3970 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3973 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
3975 unsigned long flags
;
3978 init_waitqueue_entry(&wait
, current
);
3980 __set_current_state(state
);
3982 spin_lock_irqsave(&q
->lock
, flags
);
3983 __add_wait_queue(q
, &wait
);
3984 spin_unlock(&q
->lock
);
3985 timeout
= schedule_timeout(timeout
);
3986 spin_lock_irq(&q
->lock
);
3987 __remove_wait_queue(q
, &wait
);
3988 spin_unlock_irqrestore(&q
->lock
, flags
);
3993 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3995 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3997 EXPORT_SYMBOL(interruptible_sleep_on
);
4000 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4002 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
4004 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
4006 void __sched
sleep_on(wait_queue_head_t
*q
)
4008 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
4010 EXPORT_SYMBOL(sleep_on
);
4012 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
4014 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
4016 EXPORT_SYMBOL(sleep_on_timeout
);
4018 #ifdef CONFIG_RT_MUTEXES
4021 * rt_mutex_setprio - set the current priority of a task
4023 * @prio: prio value (kernel-internal form)
4025 * This function changes the 'effective' priority of a task. It does
4026 * not touch ->normal_prio like __setscheduler().
4028 * Used by the rt_mutex code to implement priority inheritance logic.
4030 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
4032 unsigned long flags
;
4033 int oldprio
, on_rq
, running
;
4036 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4038 rq
= task_rq_lock(p
, &flags
);
4039 update_rq_clock(rq
);
4042 on_rq
= p
->se
.on_rq
;
4043 running
= task_current(rq
, p
);
4045 dequeue_task(rq
, p
, 0);
4047 p
->sched_class
->put_prev_task(rq
, p
);
4051 p
->sched_class
= &rt_sched_class
;
4053 p
->sched_class
= &fair_sched_class
;
4059 p
->sched_class
->set_curr_task(rq
);
4060 enqueue_task(rq
, p
, 0);
4062 * Reschedule if we are currently running on this runqueue and
4063 * our priority decreased, or if we are not currently running on
4064 * this runqueue and our priority is higher than the current's
4067 if (p
->prio
> oldprio
)
4068 resched_task(rq
->curr
);
4070 check_preempt_curr(rq
, p
);
4073 task_rq_unlock(rq
, &flags
);
4078 void set_user_nice(struct task_struct
*p
, long nice
)
4080 int old_prio
, delta
, on_rq
;
4081 unsigned long flags
;
4084 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4087 * We have to be careful, if called from sys_setpriority(),
4088 * the task might be in the middle of scheduling on another CPU.
4090 rq
= task_rq_lock(p
, &flags
);
4091 update_rq_clock(rq
);
4093 * The RT priorities are set via sched_setscheduler(), but we still
4094 * allow the 'normal' nice value to be set - but as expected
4095 * it wont have any effect on scheduling until the task is
4096 * SCHED_FIFO/SCHED_RR:
4098 if (task_has_rt_policy(p
)) {
4099 p
->static_prio
= NICE_TO_PRIO(nice
);
4102 on_rq
= p
->se
.on_rq
;
4104 dequeue_task(rq
, p
, 0);
4106 p
->static_prio
= NICE_TO_PRIO(nice
);
4109 p
->prio
= effective_prio(p
);
4110 delta
= p
->prio
- old_prio
;
4113 enqueue_task(rq
, p
, 0);
4115 * If the task increased its priority or is running and
4116 * lowered its priority, then reschedule its CPU:
4118 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4119 resched_task(rq
->curr
);
4122 task_rq_unlock(rq
, &flags
);
4124 EXPORT_SYMBOL(set_user_nice
);
4127 * can_nice - check if a task can reduce its nice value
4131 int can_nice(const struct task_struct
*p
, const int nice
)
4133 /* convert nice value [19,-20] to rlimit style value [1,40] */
4134 int nice_rlim
= 20 - nice
;
4136 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4137 capable(CAP_SYS_NICE
));
4140 #ifdef __ARCH_WANT_SYS_NICE
4143 * sys_nice - change the priority of the current process.
4144 * @increment: priority increment
4146 * sys_setpriority is a more generic, but much slower function that
4147 * does similar things.
4149 asmlinkage
long sys_nice(int increment
)
4154 * Setpriority might change our priority at the same moment.
4155 * We don't have to worry. Conceptually one call occurs first
4156 * and we have a single winner.
4158 if (increment
< -40)
4163 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4169 if (increment
< 0 && !can_nice(current
, nice
))
4172 retval
= security_task_setnice(current
, nice
);
4176 set_user_nice(current
, nice
);
4183 * task_prio - return the priority value of a given task.
4184 * @p: the task in question.
4186 * This is the priority value as seen by users in /proc.
4187 * RT tasks are offset by -200. Normal tasks are centered
4188 * around 0, value goes from -16 to +15.
4190 int task_prio(const struct task_struct
*p
)
4192 return p
->prio
- MAX_RT_PRIO
;
4196 * task_nice - return the nice value of a given task.
4197 * @p: the task in question.
4199 int task_nice(const struct task_struct
*p
)
4201 return TASK_NICE(p
);
4203 EXPORT_SYMBOL_GPL(task_nice
);
4206 * idle_cpu - is a given cpu idle currently?
4207 * @cpu: the processor in question.
4209 int idle_cpu(int cpu
)
4211 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4215 * idle_task - return the idle task for a given cpu.
4216 * @cpu: the processor in question.
4218 struct task_struct
*idle_task(int cpu
)
4220 return cpu_rq(cpu
)->idle
;
4224 * find_process_by_pid - find a process with a matching PID value.
4225 * @pid: the pid in question.
4227 static struct task_struct
*find_process_by_pid(pid_t pid
)
4229 return pid
? find_task_by_vpid(pid
) : current
;
4232 /* Actually do priority change: must hold rq lock. */
4234 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4236 BUG_ON(p
->se
.on_rq
);
4239 switch (p
->policy
) {
4243 p
->sched_class
= &fair_sched_class
;
4247 p
->sched_class
= &rt_sched_class
;
4251 p
->rt_priority
= prio
;
4252 p
->normal_prio
= normal_prio(p
);
4253 /* we are holding p->pi_lock already */
4254 p
->prio
= rt_mutex_getprio(p
);
4259 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4260 * @p: the task in question.
4261 * @policy: new policy.
4262 * @param: structure containing the new RT priority.
4264 * NOTE that the task may be already dead.
4266 int sched_setscheduler(struct task_struct
*p
, int policy
,
4267 struct sched_param
*param
)
4269 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
4270 unsigned long flags
;
4273 /* may grab non-irq protected spin_locks */
4274 BUG_ON(in_interrupt());
4276 /* double check policy once rq lock held */
4278 policy
= oldpolicy
= p
->policy
;
4279 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4280 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4281 policy
!= SCHED_IDLE
)
4284 * Valid priorities for SCHED_FIFO and SCHED_RR are
4285 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4286 * SCHED_BATCH and SCHED_IDLE is 0.
4288 if (param
->sched_priority
< 0 ||
4289 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4290 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4292 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4296 * Allow unprivileged RT tasks to decrease priority:
4298 if (!capable(CAP_SYS_NICE
)) {
4299 if (rt_policy(policy
)) {
4300 unsigned long rlim_rtprio
;
4302 if (!lock_task_sighand(p
, &flags
))
4304 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4305 unlock_task_sighand(p
, &flags
);
4307 /* can't set/change the rt policy */
4308 if (policy
!= p
->policy
&& !rlim_rtprio
)
4311 /* can't increase priority */
4312 if (param
->sched_priority
> p
->rt_priority
&&
4313 param
->sched_priority
> rlim_rtprio
)
4317 * Like positive nice levels, dont allow tasks to
4318 * move out of SCHED_IDLE either:
4320 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4323 /* can't change other user's priorities */
4324 if ((current
->euid
!= p
->euid
) &&
4325 (current
->euid
!= p
->uid
))
4329 retval
= security_task_setscheduler(p
, policy
, param
);
4333 * make sure no PI-waiters arrive (or leave) while we are
4334 * changing the priority of the task:
4336 spin_lock_irqsave(&p
->pi_lock
, flags
);
4338 * To be able to change p->policy safely, the apropriate
4339 * runqueue lock must be held.
4341 rq
= __task_rq_lock(p
);
4342 /* recheck policy now with rq lock held */
4343 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4344 policy
= oldpolicy
= -1;
4345 __task_rq_unlock(rq
);
4346 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4349 update_rq_clock(rq
);
4350 on_rq
= p
->se
.on_rq
;
4351 running
= task_current(rq
, p
);
4353 deactivate_task(rq
, p
, 0);
4355 p
->sched_class
->put_prev_task(rq
, p
);
4359 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4363 p
->sched_class
->set_curr_task(rq
);
4364 activate_task(rq
, p
, 0);
4366 * Reschedule if we are currently running on this runqueue and
4367 * our priority decreased, or if we are not currently running on
4368 * this runqueue and our priority is higher than the current's
4371 if (p
->prio
> oldprio
)
4372 resched_task(rq
->curr
);
4374 check_preempt_curr(rq
, p
);
4377 __task_rq_unlock(rq
);
4378 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4380 rt_mutex_adjust_pi(p
);
4384 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4387 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4389 struct sched_param lparam
;
4390 struct task_struct
*p
;
4393 if (!param
|| pid
< 0)
4395 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4400 p
= find_process_by_pid(pid
);
4402 retval
= sched_setscheduler(p
, policy
, &lparam
);
4409 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4410 * @pid: the pid in question.
4411 * @policy: new policy.
4412 * @param: structure containing the new RT priority.
4415 sys_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4417 /* negative values for policy are not valid */
4421 return do_sched_setscheduler(pid
, policy
, param
);
4425 * sys_sched_setparam - set/change the RT priority of a thread
4426 * @pid: the pid in question.
4427 * @param: structure containing the new RT priority.
4429 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4431 return do_sched_setscheduler(pid
, -1, param
);
4435 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4436 * @pid: the pid in question.
4438 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4440 struct task_struct
*p
;
4447 read_lock(&tasklist_lock
);
4448 p
= find_process_by_pid(pid
);
4450 retval
= security_task_getscheduler(p
);
4454 read_unlock(&tasklist_lock
);
4459 * sys_sched_getscheduler - get the RT priority of a thread
4460 * @pid: the pid in question.
4461 * @param: structure containing the RT priority.
4463 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4465 struct sched_param lp
;
4466 struct task_struct
*p
;
4469 if (!param
|| pid
< 0)
4472 read_lock(&tasklist_lock
);
4473 p
= find_process_by_pid(pid
);
4478 retval
= security_task_getscheduler(p
);
4482 lp
.sched_priority
= p
->rt_priority
;
4483 read_unlock(&tasklist_lock
);
4486 * This one might sleep, we cannot do it with a spinlock held ...
4488 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4493 read_unlock(&tasklist_lock
);
4497 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4499 cpumask_t cpus_allowed
;
4500 struct task_struct
*p
;
4503 mutex_lock(&sched_hotcpu_mutex
);
4504 read_lock(&tasklist_lock
);
4506 p
= find_process_by_pid(pid
);
4508 read_unlock(&tasklist_lock
);
4509 mutex_unlock(&sched_hotcpu_mutex
);
4514 * It is not safe to call set_cpus_allowed with the
4515 * tasklist_lock held. We will bump the task_struct's
4516 * usage count and then drop tasklist_lock.
4519 read_unlock(&tasklist_lock
);
4522 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4523 !capable(CAP_SYS_NICE
))
4526 retval
= security_task_setscheduler(p
, 0, NULL
);
4530 cpus_allowed
= cpuset_cpus_allowed(p
);
4531 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4533 retval
= set_cpus_allowed(p
, new_mask
);
4536 cpus_allowed
= cpuset_cpus_allowed(p
);
4537 if (!cpus_subset(new_mask
, cpus_allowed
)) {
4539 * We must have raced with a concurrent cpuset
4540 * update. Just reset the cpus_allowed to the
4541 * cpuset's cpus_allowed
4543 new_mask
= cpus_allowed
;
4549 mutex_unlock(&sched_hotcpu_mutex
);
4553 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4554 cpumask_t
*new_mask
)
4556 if (len
< sizeof(cpumask_t
)) {
4557 memset(new_mask
, 0, sizeof(cpumask_t
));
4558 } else if (len
> sizeof(cpumask_t
)) {
4559 len
= sizeof(cpumask_t
);
4561 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4565 * sys_sched_setaffinity - set the cpu affinity of a process
4566 * @pid: pid of the process
4567 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4568 * @user_mask_ptr: user-space pointer to the new cpu mask
4570 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4571 unsigned long __user
*user_mask_ptr
)
4576 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4580 return sched_setaffinity(pid
, new_mask
);
4584 * Represents all cpu's present in the system
4585 * In systems capable of hotplug, this map could dynamically grow
4586 * as new cpu's are detected in the system via any platform specific
4587 * method, such as ACPI for e.g.
4590 cpumask_t cpu_present_map __read_mostly
;
4591 EXPORT_SYMBOL(cpu_present_map
);
4594 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4595 EXPORT_SYMBOL(cpu_online_map
);
4597 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4598 EXPORT_SYMBOL(cpu_possible_map
);
4601 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4603 struct task_struct
*p
;
4606 mutex_lock(&sched_hotcpu_mutex
);
4607 read_lock(&tasklist_lock
);
4610 p
= find_process_by_pid(pid
);
4614 retval
= security_task_getscheduler(p
);
4618 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4621 read_unlock(&tasklist_lock
);
4622 mutex_unlock(&sched_hotcpu_mutex
);
4628 * sys_sched_getaffinity - get the cpu affinity of a process
4629 * @pid: pid of the process
4630 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4631 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4633 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4634 unsigned long __user
*user_mask_ptr
)
4639 if (len
< sizeof(cpumask_t
))
4642 ret
= sched_getaffinity(pid
, &mask
);
4646 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4649 return sizeof(cpumask_t
);
4653 * sys_sched_yield - yield the current processor to other threads.
4655 * This function yields the current CPU to other tasks. If there are no
4656 * other threads running on this CPU then this function will return.
4658 asmlinkage
long sys_sched_yield(void)
4660 struct rq
*rq
= this_rq_lock();
4662 schedstat_inc(rq
, yld_count
);
4663 current
->sched_class
->yield_task(rq
);
4666 * Since we are going to call schedule() anyway, there's
4667 * no need to preempt or enable interrupts:
4669 __release(rq
->lock
);
4670 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4671 _raw_spin_unlock(&rq
->lock
);
4672 preempt_enable_no_resched();
4679 static void __cond_resched(void)
4681 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4682 __might_sleep(__FILE__
, __LINE__
);
4685 * The BKS might be reacquired before we have dropped
4686 * PREEMPT_ACTIVE, which could trigger a second
4687 * cond_resched() call.
4690 add_preempt_count(PREEMPT_ACTIVE
);
4692 sub_preempt_count(PREEMPT_ACTIVE
);
4693 } while (need_resched());
4696 int __sched
cond_resched(void)
4698 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4699 system_state
== SYSTEM_RUNNING
) {
4705 EXPORT_SYMBOL(cond_resched
);
4708 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4709 * call schedule, and on return reacquire the lock.
4711 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4712 * operations here to prevent schedule() from being called twice (once via
4713 * spin_unlock(), once by hand).
4715 int cond_resched_lock(spinlock_t
*lock
)
4719 if (need_lockbreak(lock
)) {
4725 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4726 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4727 _raw_spin_unlock(lock
);
4728 preempt_enable_no_resched();
4735 EXPORT_SYMBOL(cond_resched_lock
);
4737 int __sched
cond_resched_softirq(void)
4739 BUG_ON(!in_softirq());
4741 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4749 EXPORT_SYMBOL(cond_resched_softirq
);
4752 * yield - yield the current processor to other threads.
4754 * This is a shortcut for kernel-space yielding - it marks the
4755 * thread runnable and calls sys_sched_yield().
4757 void __sched
yield(void)
4759 set_current_state(TASK_RUNNING
);
4762 EXPORT_SYMBOL(yield
);
4765 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4766 * that process accounting knows that this is a task in IO wait state.
4768 * But don't do that if it is a deliberate, throttling IO wait (this task
4769 * has set its backing_dev_info: the queue against which it should throttle)
4771 void __sched
io_schedule(void)
4773 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4775 delayacct_blkio_start();
4776 atomic_inc(&rq
->nr_iowait
);
4778 atomic_dec(&rq
->nr_iowait
);
4779 delayacct_blkio_end();
4781 EXPORT_SYMBOL(io_schedule
);
4783 long __sched
io_schedule_timeout(long timeout
)
4785 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4788 delayacct_blkio_start();
4789 atomic_inc(&rq
->nr_iowait
);
4790 ret
= schedule_timeout(timeout
);
4791 atomic_dec(&rq
->nr_iowait
);
4792 delayacct_blkio_end();
4797 * sys_sched_get_priority_max - return maximum RT priority.
4798 * @policy: scheduling class.
4800 * this syscall returns the maximum rt_priority that can be used
4801 * by a given scheduling class.
4803 asmlinkage
long sys_sched_get_priority_max(int policy
)
4810 ret
= MAX_USER_RT_PRIO
-1;
4822 * sys_sched_get_priority_min - return minimum RT priority.
4823 * @policy: scheduling class.
4825 * this syscall returns the minimum rt_priority that can be used
4826 * by a given scheduling class.
4828 asmlinkage
long sys_sched_get_priority_min(int policy
)
4846 * sys_sched_rr_get_interval - return the default timeslice of a process.
4847 * @pid: pid of the process.
4848 * @interval: userspace pointer to the timeslice value.
4850 * this syscall writes the default timeslice value of a given process
4851 * into the user-space timespec buffer. A value of '0' means infinity.
4854 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4856 struct task_struct
*p
;
4857 unsigned int time_slice
;
4865 read_lock(&tasklist_lock
);
4866 p
= find_process_by_pid(pid
);
4870 retval
= security_task_getscheduler(p
);
4875 * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
4876 * tasks that are on an otherwise idle runqueue:
4879 if (p
->policy
== SCHED_RR
) {
4880 time_slice
= DEF_TIMESLICE
;
4882 struct sched_entity
*se
= &p
->se
;
4883 unsigned long flags
;
4886 rq
= task_rq_lock(p
, &flags
);
4887 if (rq
->cfs
.load
.weight
)
4888 time_slice
= NS_TO_JIFFIES(sched_slice(&rq
->cfs
, se
));
4889 task_rq_unlock(rq
, &flags
);
4891 read_unlock(&tasklist_lock
);
4892 jiffies_to_timespec(time_slice
, &t
);
4893 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4897 read_unlock(&tasklist_lock
);
4901 static const char stat_nam
[] = "RSDTtZX";
4903 static void show_task(struct task_struct
*p
)
4905 unsigned long free
= 0;
4908 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4909 printk(KERN_INFO
"%-13.13s %c", p
->comm
,
4910 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4911 #if BITS_PER_LONG == 32
4912 if (state
== TASK_RUNNING
)
4913 printk(KERN_CONT
" running ");
4915 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4917 if (state
== TASK_RUNNING
)
4918 printk(KERN_CONT
" running task ");
4920 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4922 #ifdef CONFIG_DEBUG_STACK_USAGE
4924 unsigned long *n
= end_of_stack(p
);
4927 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4930 printk(KERN_CONT
"%5lu %5d %6d\n", free
,
4931 task_pid_nr(p
), task_pid_nr(p
->real_parent
));
4933 if (state
!= TASK_RUNNING
)
4934 show_stack(p
, NULL
);
4937 void show_state_filter(unsigned long state_filter
)
4939 struct task_struct
*g
, *p
;
4941 #if BITS_PER_LONG == 32
4943 " task PC stack pid father\n");
4946 " task PC stack pid father\n");
4948 read_lock(&tasklist_lock
);
4949 do_each_thread(g
, p
) {
4951 * reset the NMI-timeout, listing all files on a slow
4952 * console might take alot of time:
4954 touch_nmi_watchdog();
4955 if (!state_filter
|| (p
->state
& state_filter
))
4957 } while_each_thread(g
, p
);
4959 touch_all_softlockup_watchdogs();
4961 #ifdef CONFIG_SCHED_DEBUG
4962 sysrq_sched_debug_show();
4964 read_unlock(&tasklist_lock
);
4966 * Only show locks if all tasks are dumped:
4968 if (state_filter
== -1)
4969 debug_show_all_locks();
4972 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4974 idle
->sched_class
= &idle_sched_class
;
4978 * init_idle - set up an idle thread for a given CPU
4979 * @idle: task in question
4980 * @cpu: cpu the idle task belongs to
4982 * NOTE: this function does not set the idle thread's NEED_RESCHED
4983 * flag, to make booting more robust.
4985 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4987 struct rq
*rq
= cpu_rq(cpu
);
4988 unsigned long flags
;
4991 idle
->se
.exec_start
= sched_clock();
4993 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4994 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4995 __set_task_cpu(idle
, cpu
);
4997 spin_lock_irqsave(&rq
->lock
, flags
);
4998 rq
->curr
= rq
->idle
= idle
;
4999 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5002 spin_unlock_irqrestore(&rq
->lock
, flags
);
5004 /* Set the preempt count _outside_ the spinlocks! */
5005 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
5006 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
5008 task_thread_info(idle
)->preempt_count
= 0;
5011 * The idle tasks have their own, simple scheduling class:
5013 idle
->sched_class
= &idle_sched_class
;
5017 * In a system that switches off the HZ timer nohz_cpu_mask
5018 * indicates which cpus entered this state. This is used
5019 * in the rcu update to wait only for active cpus. For system
5020 * which do not switch off the HZ timer nohz_cpu_mask should
5021 * always be CPU_MASK_NONE.
5023 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
5026 * Increase the granularity value when there are more CPUs,
5027 * because with more CPUs the 'effective latency' as visible
5028 * to users decreases. But the relationship is not linear,
5029 * so pick a second-best guess by going with the log2 of the
5032 * This idea comes from the SD scheduler of Con Kolivas:
5034 static inline void sched_init_granularity(void)
5036 unsigned int factor
= 1 + ilog2(num_online_cpus());
5037 const unsigned long limit
= 200000000;
5039 sysctl_sched_min_granularity
*= factor
;
5040 if (sysctl_sched_min_granularity
> limit
)
5041 sysctl_sched_min_granularity
= limit
;
5043 sysctl_sched_latency
*= factor
;
5044 if (sysctl_sched_latency
> limit
)
5045 sysctl_sched_latency
= limit
;
5047 sysctl_sched_wakeup_granularity
*= factor
;
5048 sysctl_sched_batch_wakeup_granularity
*= factor
;
5053 * This is how migration works:
5055 * 1) we queue a struct migration_req structure in the source CPU's
5056 * runqueue and wake up that CPU's migration thread.
5057 * 2) we down() the locked semaphore => thread blocks.
5058 * 3) migration thread wakes up (implicitly it forces the migrated
5059 * thread off the CPU)
5060 * 4) it gets the migration request and checks whether the migrated
5061 * task is still in the wrong runqueue.
5062 * 5) if it's in the wrong runqueue then the migration thread removes
5063 * it and puts it into the right queue.
5064 * 6) migration thread up()s the semaphore.
5065 * 7) we wake up and the migration is done.
5069 * Change a given task's CPU affinity. Migrate the thread to a
5070 * proper CPU and schedule it away if the CPU it's executing on
5071 * is removed from the allowed bitmask.
5073 * NOTE: the caller must have a valid reference to the task, the
5074 * task must not exit() & deallocate itself prematurely. The
5075 * call is not atomic; no spinlocks may be held.
5077 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5079 struct migration_req req
;
5080 unsigned long flags
;
5084 rq
= task_rq_lock(p
, &flags
);
5085 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5090 p
->cpus_allowed
= new_mask
;
5091 /* Can the task run on the task's current CPU? If so, we're done */
5092 if (cpu_isset(task_cpu(p
), new_mask
))
5095 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5096 /* Need help from migration thread: drop lock and wait. */
5097 task_rq_unlock(rq
, &flags
);
5098 wake_up_process(rq
->migration_thread
);
5099 wait_for_completion(&req
.done
);
5100 tlb_migrate_finish(p
->mm
);
5104 task_rq_unlock(rq
, &flags
);
5108 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5111 * Move (not current) task off this cpu, onto dest cpu. We're doing
5112 * this because either it can't run here any more (set_cpus_allowed()
5113 * away from this CPU, or CPU going down), or because we're
5114 * attempting to rebalance this task on exec (sched_exec).
5116 * So we race with normal scheduler movements, but that's OK, as long
5117 * as the task is no longer on this CPU.
5119 * Returns non-zero if task was successfully migrated.
5121 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5123 struct rq
*rq_dest
, *rq_src
;
5126 if (unlikely(cpu_is_offline(dest_cpu
)))
5129 rq_src
= cpu_rq(src_cpu
);
5130 rq_dest
= cpu_rq(dest_cpu
);
5132 double_rq_lock(rq_src
, rq_dest
);
5133 /* Already moved. */
5134 if (task_cpu(p
) != src_cpu
)
5136 /* Affinity changed (again). */
5137 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5140 on_rq
= p
->se
.on_rq
;
5142 deactivate_task(rq_src
, p
, 0);
5144 set_task_cpu(p
, dest_cpu
);
5146 activate_task(rq_dest
, p
, 0);
5147 check_preempt_curr(rq_dest
, p
);
5151 double_rq_unlock(rq_src
, rq_dest
);
5156 * migration_thread - this is a highprio system thread that performs
5157 * thread migration by bumping thread off CPU then 'pushing' onto
5160 static int migration_thread(void *data
)
5162 int cpu
= (long)data
;
5166 BUG_ON(rq
->migration_thread
!= current
);
5168 set_current_state(TASK_INTERRUPTIBLE
);
5169 while (!kthread_should_stop()) {
5170 struct migration_req
*req
;
5171 struct list_head
*head
;
5173 spin_lock_irq(&rq
->lock
);
5175 if (cpu_is_offline(cpu
)) {
5176 spin_unlock_irq(&rq
->lock
);
5180 if (rq
->active_balance
) {
5181 active_load_balance(rq
, cpu
);
5182 rq
->active_balance
= 0;
5185 head
= &rq
->migration_queue
;
5187 if (list_empty(head
)) {
5188 spin_unlock_irq(&rq
->lock
);
5190 set_current_state(TASK_INTERRUPTIBLE
);
5193 req
= list_entry(head
->next
, struct migration_req
, list
);
5194 list_del_init(head
->next
);
5196 spin_unlock(&rq
->lock
);
5197 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5200 complete(&req
->done
);
5202 __set_current_state(TASK_RUNNING
);
5206 /* Wait for kthread_stop */
5207 set_current_state(TASK_INTERRUPTIBLE
);
5208 while (!kthread_should_stop()) {
5210 set_current_state(TASK_INTERRUPTIBLE
);
5212 __set_current_state(TASK_RUNNING
);
5216 #ifdef CONFIG_HOTPLUG_CPU
5218 static int __migrate_task_irq(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5222 local_irq_disable();
5223 ret
= __migrate_task(p
, src_cpu
, dest_cpu
);
5229 * Figure out where task on dead CPU should go, use force if necessary.
5230 * NOTE: interrupts should be disabled by the caller
5232 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5234 unsigned long flags
;
5241 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5242 cpus_and(mask
, mask
, p
->cpus_allowed
);
5243 dest_cpu
= any_online_cpu(mask
);
5245 /* On any allowed CPU? */
5246 if (dest_cpu
== NR_CPUS
)
5247 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5249 /* No more Mr. Nice Guy. */
5250 if (dest_cpu
== NR_CPUS
) {
5251 cpumask_t cpus_allowed
= cpuset_cpus_allowed_locked(p
);
5253 * Try to stay on the same cpuset, where the
5254 * current cpuset may be a subset of all cpus.
5255 * The cpuset_cpus_allowed_locked() variant of
5256 * cpuset_cpus_allowed() will not block. It must be
5257 * called within calls to cpuset_lock/cpuset_unlock.
5259 rq
= task_rq_lock(p
, &flags
);
5260 p
->cpus_allowed
= cpus_allowed
;
5261 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5262 task_rq_unlock(rq
, &flags
);
5265 * Don't tell them about moving exiting tasks or
5266 * kernel threads (both mm NULL), since they never
5269 if (p
->mm
&& printk_ratelimit()) {
5270 printk(KERN_INFO
"process %d (%s) no "
5271 "longer affine to cpu%d\n",
5272 task_pid_nr(p
), p
->comm
, dead_cpu
);
5275 } while (!__migrate_task_irq(p
, dead_cpu
, dest_cpu
));
5279 * While a dead CPU has no uninterruptible tasks queued at this point,
5280 * it might still have a nonzero ->nr_uninterruptible counter, because
5281 * for performance reasons the counter is not stricly tracking tasks to
5282 * their home CPUs. So we just add the counter to another CPU's counter,
5283 * to keep the global sum constant after CPU-down:
5285 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5287 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5288 unsigned long flags
;
5290 local_irq_save(flags
);
5291 double_rq_lock(rq_src
, rq_dest
);
5292 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5293 rq_src
->nr_uninterruptible
= 0;
5294 double_rq_unlock(rq_src
, rq_dest
);
5295 local_irq_restore(flags
);
5298 /* Run through task list and migrate tasks from the dead cpu. */
5299 static void migrate_live_tasks(int src_cpu
)
5301 struct task_struct
*p
, *t
;
5303 read_lock(&tasklist_lock
);
5305 do_each_thread(t
, p
) {
5309 if (task_cpu(p
) == src_cpu
)
5310 move_task_off_dead_cpu(src_cpu
, p
);
5311 } while_each_thread(t
, p
);
5313 read_unlock(&tasklist_lock
);
5317 * Schedules idle task to be the next runnable task on current CPU.
5318 * It does so by boosting its priority to highest possible.
5319 * Used by CPU offline code.
5321 void sched_idle_next(void)
5323 int this_cpu
= smp_processor_id();
5324 struct rq
*rq
= cpu_rq(this_cpu
);
5325 struct task_struct
*p
= rq
->idle
;
5326 unsigned long flags
;
5328 /* cpu has to be offline */
5329 BUG_ON(cpu_online(this_cpu
));
5332 * Strictly not necessary since rest of the CPUs are stopped by now
5333 * and interrupts disabled on the current cpu.
5335 spin_lock_irqsave(&rq
->lock
, flags
);
5337 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5339 update_rq_clock(rq
);
5340 activate_task(rq
, p
, 0);
5342 spin_unlock_irqrestore(&rq
->lock
, flags
);
5346 * Ensures that the idle task is using init_mm right before its cpu goes
5349 void idle_task_exit(void)
5351 struct mm_struct
*mm
= current
->active_mm
;
5353 BUG_ON(cpu_online(smp_processor_id()));
5356 switch_mm(mm
, &init_mm
, current
);
5360 /* called under rq->lock with disabled interrupts */
5361 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5363 struct rq
*rq
= cpu_rq(dead_cpu
);
5365 /* Must be exiting, otherwise would be on tasklist. */
5366 BUG_ON(!p
->exit_state
);
5368 /* Cannot have done final schedule yet: would have vanished. */
5369 BUG_ON(p
->state
== TASK_DEAD
);
5374 * Drop lock around migration; if someone else moves it,
5375 * that's OK. No task can be added to this CPU, so iteration is
5378 spin_unlock_irq(&rq
->lock
);
5379 move_task_off_dead_cpu(dead_cpu
, p
);
5380 spin_lock_irq(&rq
->lock
);
5385 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5386 static void migrate_dead_tasks(unsigned int dead_cpu
)
5388 struct rq
*rq
= cpu_rq(dead_cpu
);
5389 struct task_struct
*next
;
5392 if (!rq
->nr_running
)
5394 update_rq_clock(rq
);
5395 next
= pick_next_task(rq
, rq
->curr
);
5398 migrate_dead(dead_cpu
, next
);
5402 #endif /* CONFIG_HOTPLUG_CPU */
5404 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5406 static struct ctl_table sd_ctl_dir
[] = {
5408 .procname
= "sched_domain",
5414 static struct ctl_table sd_ctl_root
[] = {
5416 .ctl_name
= CTL_KERN
,
5417 .procname
= "kernel",
5419 .child
= sd_ctl_dir
,
5424 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5426 struct ctl_table
*entry
=
5427 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5432 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5434 struct ctl_table
*entry
;
5437 * In the intermediate directories, both the child directory and
5438 * procname are dynamically allocated and could fail but the mode
5439 * will always be set. In the lowest directory the names are
5440 * static strings and all have proc handlers.
5442 for (entry
= *tablep
; entry
->mode
; entry
++) {
5444 sd_free_ctl_entry(&entry
->child
);
5445 if (entry
->proc_handler
== NULL
)
5446 kfree(entry
->procname
);
5454 set_table_entry(struct ctl_table
*entry
,
5455 const char *procname
, void *data
, int maxlen
,
5456 mode_t mode
, proc_handler
*proc_handler
)
5458 entry
->procname
= procname
;
5460 entry
->maxlen
= maxlen
;
5462 entry
->proc_handler
= proc_handler
;
5465 static struct ctl_table
*
5466 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5468 struct ctl_table
*table
= sd_alloc_ctl_entry(12);
5473 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5474 sizeof(long), 0644, proc_doulongvec_minmax
);
5475 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5476 sizeof(long), 0644, proc_doulongvec_minmax
);
5477 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5478 sizeof(int), 0644, proc_dointvec_minmax
);
5479 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5480 sizeof(int), 0644, proc_dointvec_minmax
);
5481 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5482 sizeof(int), 0644, proc_dointvec_minmax
);
5483 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5484 sizeof(int), 0644, proc_dointvec_minmax
);
5485 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5486 sizeof(int), 0644, proc_dointvec_minmax
);
5487 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5488 sizeof(int), 0644, proc_dointvec_minmax
);
5489 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5490 sizeof(int), 0644, proc_dointvec_minmax
);
5491 set_table_entry(&table
[9], "cache_nice_tries",
5492 &sd
->cache_nice_tries
,
5493 sizeof(int), 0644, proc_dointvec_minmax
);
5494 set_table_entry(&table
[10], "flags", &sd
->flags
,
5495 sizeof(int), 0644, proc_dointvec_minmax
);
5496 /* &table[11] is terminator */
5501 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5503 struct ctl_table
*entry
, *table
;
5504 struct sched_domain
*sd
;
5505 int domain_num
= 0, i
;
5508 for_each_domain(cpu
, sd
)
5510 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5515 for_each_domain(cpu
, sd
) {
5516 snprintf(buf
, 32, "domain%d", i
);
5517 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5519 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5526 static struct ctl_table_header
*sd_sysctl_header
;
5527 static void register_sched_domain_sysctl(void)
5529 int i
, cpu_num
= num_online_cpus();
5530 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5533 WARN_ON(sd_ctl_dir
[0].child
);
5534 sd_ctl_dir
[0].child
= entry
;
5539 for_each_online_cpu(i
) {
5540 snprintf(buf
, 32, "cpu%d", i
);
5541 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5543 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5547 WARN_ON(sd_sysctl_header
);
5548 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5551 /* may be called multiple times per register */
5552 static void unregister_sched_domain_sysctl(void)
5554 if (sd_sysctl_header
)
5555 unregister_sysctl_table(sd_sysctl_header
);
5556 sd_sysctl_header
= NULL
;
5557 if (sd_ctl_dir
[0].child
)
5558 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5561 static void register_sched_domain_sysctl(void)
5564 static void unregister_sched_domain_sysctl(void)
5570 * migration_call - callback that gets triggered when a CPU is added.
5571 * Here we can start up the necessary migration thread for the new CPU.
5573 static int __cpuinit
5574 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5576 struct task_struct
*p
;
5577 int cpu
= (long)hcpu
;
5578 unsigned long flags
;
5582 case CPU_LOCK_ACQUIRE
:
5583 mutex_lock(&sched_hotcpu_mutex
);
5586 case CPU_UP_PREPARE
:
5587 case CPU_UP_PREPARE_FROZEN
:
5588 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5591 kthread_bind(p
, cpu
);
5592 /* Must be high prio: stop_machine expects to yield to it. */
5593 rq
= task_rq_lock(p
, &flags
);
5594 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5595 task_rq_unlock(rq
, &flags
);
5596 cpu_rq(cpu
)->migration_thread
= p
;
5600 case CPU_ONLINE_FROZEN
:
5601 /* Strictly unnecessary, as first user will wake it. */
5602 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5605 #ifdef CONFIG_HOTPLUG_CPU
5606 case CPU_UP_CANCELED
:
5607 case CPU_UP_CANCELED_FROZEN
:
5608 if (!cpu_rq(cpu
)->migration_thread
)
5610 /* Unbind it from offline cpu so it can run. Fall thru. */
5611 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5612 any_online_cpu(cpu_online_map
));
5613 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5614 cpu_rq(cpu
)->migration_thread
= NULL
;
5618 case CPU_DEAD_FROZEN
:
5619 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
5620 migrate_live_tasks(cpu
);
5622 kthread_stop(rq
->migration_thread
);
5623 rq
->migration_thread
= NULL
;
5624 /* Idle task back to normal (off runqueue, low prio) */
5625 spin_lock_irq(&rq
->lock
);
5626 update_rq_clock(rq
);
5627 deactivate_task(rq
, rq
->idle
, 0);
5628 rq
->idle
->static_prio
= MAX_PRIO
;
5629 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5630 rq
->idle
->sched_class
= &idle_sched_class
;
5631 migrate_dead_tasks(cpu
);
5632 spin_unlock_irq(&rq
->lock
);
5634 migrate_nr_uninterruptible(rq
);
5635 BUG_ON(rq
->nr_running
!= 0);
5638 * No need to migrate the tasks: it was best-effort if
5639 * they didn't take sched_hotcpu_mutex. Just wake up
5642 spin_lock_irq(&rq
->lock
);
5643 while (!list_empty(&rq
->migration_queue
)) {
5644 struct migration_req
*req
;
5646 req
= list_entry(rq
->migration_queue
.next
,
5647 struct migration_req
, list
);
5648 list_del_init(&req
->list
);
5649 complete(&req
->done
);
5651 spin_unlock_irq(&rq
->lock
);
5654 case CPU_LOCK_RELEASE
:
5655 mutex_unlock(&sched_hotcpu_mutex
);
5661 /* Register at highest priority so that task migration (migrate_all_tasks)
5662 * happens before everything else.
5664 static struct notifier_block __cpuinitdata migration_notifier
= {
5665 .notifier_call
= migration_call
,
5669 void __init
migration_init(void)
5671 void *cpu
= (void *)(long)smp_processor_id();
5674 /* Start one for the boot CPU: */
5675 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5676 BUG_ON(err
== NOTIFY_BAD
);
5677 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5678 register_cpu_notifier(&migration_notifier
);
5684 /* Number of possible processor ids */
5685 int nr_cpu_ids __read_mostly
= NR_CPUS
;
5686 EXPORT_SYMBOL(nr_cpu_ids
);
5688 #ifdef CONFIG_SCHED_DEBUG
5690 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
)
5692 struct sched_group
*group
= sd
->groups
;
5693 cpumask_t groupmask
;
5696 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5697 cpus_clear(groupmask
);
5699 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5701 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5702 printk("does not load-balance\n");
5704 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5709 printk(KERN_CONT
"span %s\n", str
);
5711 if (!cpu_isset(cpu
, sd
->span
)) {
5712 printk(KERN_ERR
"ERROR: domain->span does not contain "
5715 if (!cpu_isset(cpu
, group
->cpumask
)) {
5716 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5720 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5724 printk(KERN_ERR
"ERROR: group is NULL\n");
5728 if (!group
->__cpu_power
) {
5729 printk(KERN_CONT
"\n");
5730 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5735 if (!cpus_weight(group
->cpumask
)) {
5736 printk(KERN_CONT
"\n");
5737 printk(KERN_ERR
"ERROR: empty group\n");
5741 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5742 printk(KERN_CONT
"\n");
5743 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5747 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5749 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5750 printk(KERN_CONT
" %s", str
);
5752 group
= group
->next
;
5753 } while (group
!= sd
->groups
);
5754 printk(KERN_CONT
"\n");
5756 if (!cpus_equal(sd
->span
, groupmask
))
5757 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5759 if (sd
->parent
&& !cpus_subset(groupmask
, sd
->parent
->span
))
5760 printk(KERN_ERR
"ERROR: parent span is not a superset "
5761 "of domain->span\n");
5765 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5770 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5774 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5777 if (sched_domain_debug_one(sd
, cpu
, level
))
5786 # define sched_domain_debug(sd, cpu) do { } while (0)
5789 static int sd_degenerate(struct sched_domain
*sd
)
5791 if (cpus_weight(sd
->span
) == 1)
5794 /* Following flags need at least 2 groups */
5795 if (sd
->flags
& (SD_LOAD_BALANCE
|
5796 SD_BALANCE_NEWIDLE
|
5800 SD_SHARE_PKG_RESOURCES
)) {
5801 if (sd
->groups
!= sd
->groups
->next
)
5805 /* Following flags don't use groups */
5806 if (sd
->flags
& (SD_WAKE_IDLE
|
5815 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5817 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5819 if (sd_degenerate(parent
))
5822 if (!cpus_equal(sd
->span
, parent
->span
))
5825 /* Does parent contain flags not in child? */
5826 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5827 if (cflags
& SD_WAKE_AFFINE
)
5828 pflags
&= ~SD_WAKE_BALANCE
;
5829 /* Flags needing groups don't count if only 1 group in parent */
5830 if (parent
->groups
== parent
->groups
->next
) {
5831 pflags
&= ~(SD_LOAD_BALANCE
|
5832 SD_BALANCE_NEWIDLE
|
5836 SD_SHARE_PKG_RESOURCES
);
5838 if (~cflags
& pflags
)
5845 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5846 * hold the hotplug lock.
5848 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5850 struct rq
*rq
= cpu_rq(cpu
);
5851 struct sched_domain
*tmp
;
5853 /* Remove the sched domains which do not contribute to scheduling. */
5854 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5855 struct sched_domain
*parent
= tmp
->parent
;
5858 if (sd_parent_degenerate(tmp
, parent
)) {
5859 tmp
->parent
= parent
->parent
;
5861 parent
->parent
->child
= tmp
;
5865 if (sd
&& sd_degenerate(sd
)) {
5871 sched_domain_debug(sd
, cpu
);
5873 rcu_assign_pointer(rq
->sd
, sd
);
5876 /* cpus with isolated domains */
5877 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5879 /* Setup the mask of cpus configured for isolated domains */
5880 static int __init
isolated_cpu_setup(char *str
)
5882 int ints
[NR_CPUS
], i
;
5884 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5885 cpus_clear(cpu_isolated_map
);
5886 for (i
= 1; i
<= ints
[0]; i
++)
5887 if (ints
[i
] < NR_CPUS
)
5888 cpu_set(ints
[i
], cpu_isolated_map
);
5892 __setup("isolcpus=", isolated_cpu_setup
);
5895 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5896 * to a function which identifies what group(along with sched group) a CPU
5897 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5898 * (due to the fact that we keep track of groups covered with a cpumask_t).
5900 * init_sched_build_groups will build a circular linked list of the groups
5901 * covered by the given span, and will set each group's ->cpumask correctly,
5902 * and ->cpu_power to 0.
5905 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5906 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5907 struct sched_group
**sg
))
5909 struct sched_group
*first
= NULL
, *last
= NULL
;
5910 cpumask_t covered
= CPU_MASK_NONE
;
5913 for_each_cpu_mask(i
, span
) {
5914 struct sched_group
*sg
;
5915 int group
= group_fn(i
, cpu_map
, &sg
);
5918 if (cpu_isset(i
, covered
))
5921 sg
->cpumask
= CPU_MASK_NONE
;
5922 sg
->__cpu_power
= 0;
5924 for_each_cpu_mask(j
, span
) {
5925 if (group_fn(j
, cpu_map
, NULL
) != group
)
5928 cpu_set(j
, covered
);
5929 cpu_set(j
, sg
->cpumask
);
5940 #define SD_NODES_PER_DOMAIN 16
5945 * find_next_best_node - find the next node to include in a sched_domain
5946 * @node: node whose sched_domain we're building
5947 * @used_nodes: nodes already in the sched_domain
5949 * Find the next node to include in a given scheduling domain. Simply
5950 * finds the closest node not already in the @used_nodes map.
5952 * Should use nodemask_t.
5954 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5956 int i
, n
, val
, min_val
, best_node
= 0;
5960 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5961 /* Start at @node */
5962 n
= (node
+ i
) % MAX_NUMNODES
;
5964 if (!nr_cpus_node(n
))
5967 /* Skip already used nodes */
5968 if (test_bit(n
, used_nodes
))
5971 /* Simple min distance search */
5972 val
= node_distance(node
, n
);
5974 if (val
< min_val
) {
5980 set_bit(best_node
, used_nodes
);
5985 * sched_domain_node_span - get a cpumask for a node's sched_domain
5986 * @node: node whose cpumask we're constructing
5987 * @size: number of nodes to include in this span
5989 * Given a node, construct a good cpumask for its sched_domain to span. It
5990 * should be one that prevents unnecessary balancing, but also spreads tasks
5993 static cpumask_t
sched_domain_node_span(int node
)
5995 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5996 cpumask_t span
, nodemask
;
6000 bitmap_zero(used_nodes
, MAX_NUMNODES
);
6002 nodemask
= node_to_cpumask(node
);
6003 cpus_or(span
, span
, nodemask
);
6004 set_bit(node
, used_nodes
);
6006 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6007 int next_node
= find_next_best_node(node
, used_nodes
);
6009 nodemask
= node_to_cpumask(next_node
);
6010 cpus_or(span
, span
, nodemask
);
6017 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
6020 * SMT sched-domains:
6022 #ifdef CONFIG_SCHED_SMT
6023 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
6024 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6027 cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6030 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6036 * multi-core sched-domains:
6038 #ifdef CONFIG_SCHED_MC
6039 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6040 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6043 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6045 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6048 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6049 cpus_and(mask
, mask
, *cpu_map
);
6050 group
= first_cpu(mask
);
6052 *sg
= &per_cpu(sched_group_core
, group
);
6055 #elif defined(CONFIG_SCHED_MC)
6057 cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6060 *sg
= &per_cpu(sched_group_core
, cpu
);
6065 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6066 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6069 cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
, struct sched_group
**sg
)
6072 #ifdef CONFIG_SCHED_MC
6073 cpumask_t mask
= cpu_coregroup_map(cpu
);
6074 cpus_and(mask
, mask
, *cpu_map
);
6075 group
= first_cpu(mask
);
6076 #elif defined(CONFIG_SCHED_SMT)
6077 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6078 cpus_and(mask
, mask
, *cpu_map
);
6079 group
= first_cpu(mask
);
6084 *sg
= &per_cpu(sched_group_phys
, group
);
6090 * The init_sched_build_groups can't handle what we want to do with node
6091 * groups, so roll our own. Now each node has its own list of groups which
6092 * gets dynamically allocated.
6094 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6095 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6097 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6098 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6100 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6101 struct sched_group
**sg
)
6103 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6106 cpus_and(nodemask
, nodemask
, *cpu_map
);
6107 group
= first_cpu(nodemask
);
6110 *sg
= &per_cpu(sched_group_allnodes
, group
);
6114 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6116 struct sched_group
*sg
= group_head
;
6122 for_each_cpu_mask(j
, sg
->cpumask
) {
6123 struct sched_domain
*sd
;
6125 sd
= &per_cpu(phys_domains
, j
);
6126 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6128 * Only add "power" once for each
6134 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
6137 } while (sg
!= group_head
);
6142 /* Free memory allocated for various sched_group structures */
6143 static void free_sched_groups(const cpumask_t
*cpu_map
)
6147 for_each_cpu_mask(cpu
, *cpu_map
) {
6148 struct sched_group
**sched_group_nodes
6149 = sched_group_nodes_bycpu
[cpu
];
6151 if (!sched_group_nodes
)
6154 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6155 cpumask_t nodemask
= node_to_cpumask(i
);
6156 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6158 cpus_and(nodemask
, nodemask
, *cpu_map
);
6159 if (cpus_empty(nodemask
))
6169 if (oldsg
!= sched_group_nodes
[i
])
6172 kfree(sched_group_nodes
);
6173 sched_group_nodes_bycpu
[cpu
] = NULL
;
6177 static void free_sched_groups(const cpumask_t
*cpu_map
)
6183 * Initialize sched groups cpu_power.
6185 * cpu_power indicates the capacity of sched group, which is used while
6186 * distributing the load between different sched groups in a sched domain.
6187 * Typically cpu_power for all the groups in a sched domain will be same unless
6188 * there are asymmetries in the topology. If there are asymmetries, group
6189 * having more cpu_power will pickup more load compared to the group having
6192 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6193 * the maximum number of tasks a group can handle in the presence of other idle
6194 * or lightly loaded groups in the same sched domain.
6196 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6198 struct sched_domain
*child
;
6199 struct sched_group
*group
;
6201 WARN_ON(!sd
|| !sd
->groups
);
6203 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6208 sd
->groups
->__cpu_power
= 0;
6211 * For perf policy, if the groups in child domain share resources
6212 * (for example cores sharing some portions of the cache hierarchy
6213 * or SMT), then set this domain groups cpu_power such that each group
6214 * can handle only one task, when there are other idle groups in the
6215 * same sched domain.
6217 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6219 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6220 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
6225 * add cpu_power of each child group to this groups cpu_power
6227 group
= child
->groups
;
6229 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
6230 group
= group
->next
;
6231 } while (group
!= child
->groups
);
6235 * Build sched domains for a given set of cpus and attach the sched domains
6236 * to the individual cpus
6238 static int build_sched_domains(const cpumask_t
*cpu_map
)
6242 struct sched_group
**sched_group_nodes
= NULL
;
6243 int sd_allnodes
= 0;
6246 * Allocate the per-node list of sched groups
6248 sched_group_nodes
= kcalloc(MAX_NUMNODES
, sizeof(struct sched_group
*),
6250 if (!sched_group_nodes
) {
6251 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6254 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6258 * Set up domains for cpus specified by the cpu_map.
6260 for_each_cpu_mask(i
, *cpu_map
) {
6261 struct sched_domain
*sd
= NULL
, *p
;
6262 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6264 cpus_and(nodemask
, nodemask
, *cpu_map
);
6267 if (cpus_weight(*cpu_map
) >
6268 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6269 sd
= &per_cpu(allnodes_domains
, i
);
6270 *sd
= SD_ALLNODES_INIT
;
6271 sd
->span
= *cpu_map
;
6272 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6278 sd
= &per_cpu(node_domains
, i
);
6280 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6284 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6288 sd
= &per_cpu(phys_domains
, i
);
6290 sd
->span
= nodemask
;
6294 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6296 #ifdef CONFIG_SCHED_MC
6298 sd
= &per_cpu(core_domains
, i
);
6300 sd
->span
= cpu_coregroup_map(i
);
6301 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6304 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6307 #ifdef CONFIG_SCHED_SMT
6309 sd
= &per_cpu(cpu_domains
, i
);
6310 *sd
= SD_SIBLING_INIT
;
6311 sd
->span
= per_cpu(cpu_sibling_map
, i
);
6312 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6315 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6319 #ifdef CONFIG_SCHED_SMT
6320 /* Set up CPU (sibling) groups */
6321 for_each_cpu_mask(i
, *cpu_map
) {
6322 cpumask_t this_sibling_map
= per_cpu(cpu_sibling_map
, i
);
6323 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6324 if (i
!= first_cpu(this_sibling_map
))
6327 init_sched_build_groups(this_sibling_map
, cpu_map
,
6332 #ifdef CONFIG_SCHED_MC
6333 /* Set up multi-core groups */
6334 for_each_cpu_mask(i
, *cpu_map
) {
6335 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6336 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6337 if (i
!= first_cpu(this_core_map
))
6339 init_sched_build_groups(this_core_map
, cpu_map
,
6340 &cpu_to_core_group
);
6344 /* Set up physical groups */
6345 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6346 cpumask_t nodemask
= node_to_cpumask(i
);
6348 cpus_and(nodemask
, nodemask
, *cpu_map
);
6349 if (cpus_empty(nodemask
))
6352 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6356 /* Set up node groups */
6358 init_sched_build_groups(*cpu_map
, cpu_map
,
6359 &cpu_to_allnodes_group
);
6361 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6362 /* Set up node groups */
6363 struct sched_group
*sg
, *prev
;
6364 cpumask_t nodemask
= node_to_cpumask(i
);
6365 cpumask_t domainspan
;
6366 cpumask_t covered
= CPU_MASK_NONE
;
6369 cpus_and(nodemask
, nodemask
, *cpu_map
);
6370 if (cpus_empty(nodemask
)) {
6371 sched_group_nodes
[i
] = NULL
;
6375 domainspan
= sched_domain_node_span(i
);
6376 cpus_and(domainspan
, domainspan
, *cpu_map
);
6378 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6380 printk(KERN_WARNING
"Can not alloc domain group for "
6384 sched_group_nodes
[i
] = sg
;
6385 for_each_cpu_mask(j
, nodemask
) {
6386 struct sched_domain
*sd
;
6388 sd
= &per_cpu(node_domains
, j
);
6391 sg
->__cpu_power
= 0;
6392 sg
->cpumask
= nodemask
;
6394 cpus_or(covered
, covered
, nodemask
);
6397 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6398 cpumask_t tmp
, notcovered
;
6399 int n
= (i
+ j
) % MAX_NUMNODES
;
6401 cpus_complement(notcovered
, covered
);
6402 cpus_and(tmp
, notcovered
, *cpu_map
);
6403 cpus_and(tmp
, tmp
, domainspan
);
6404 if (cpus_empty(tmp
))
6407 nodemask
= node_to_cpumask(n
);
6408 cpus_and(tmp
, tmp
, nodemask
);
6409 if (cpus_empty(tmp
))
6412 sg
= kmalloc_node(sizeof(struct sched_group
),
6416 "Can not alloc domain group for node %d\n", j
);
6419 sg
->__cpu_power
= 0;
6421 sg
->next
= prev
->next
;
6422 cpus_or(covered
, covered
, tmp
);
6429 /* Calculate CPU power for physical packages and nodes */
6430 #ifdef CONFIG_SCHED_SMT
6431 for_each_cpu_mask(i
, *cpu_map
) {
6432 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6434 init_sched_groups_power(i
, sd
);
6437 #ifdef CONFIG_SCHED_MC
6438 for_each_cpu_mask(i
, *cpu_map
) {
6439 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6441 init_sched_groups_power(i
, sd
);
6445 for_each_cpu_mask(i
, *cpu_map
) {
6446 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6448 init_sched_groups_power(i
, sd
);
6452 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6453 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6456 struct sched_group
*sg
;
6458 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6459 init_numa_sched_groups_power(sg
);
6463 /* Attach the domains */
6464 for_each_cpu_mask(i
, *cpu_map
) {
6465 struct sched_domain
*sd
;
6466 #ifdef CONFIG_SCHED_SMT
6467 sd
= &per_cpu(cpu_domains
, i
);
6468 #elif defined(CONFIG_SCHED_MC)
6469 sd
= &per_cpu(core_domains
, i
);
6471 sd
= &per_cpu(phys_domains
, i
);
6473 cpu_attach_domain(sd
, i
);
6480 free_sched_groups(cpu_map
);
6485 static cpumask_t
*doms_cur
; /* current sched domains */
6486 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6489 * Special case: If a kmalloc of a doms_cur partition (array of
6490 * cpumask_t) fails, then fallback to a single sched domain,
6491 * as determined by the single cpumask_t fallback_doms.
6493 static cpumask_t fallback_doms
;
6496 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6497 * For now this just excludes isolated cpus, but could be used to
6498 * exclude other special cases in the future.
6500 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6505 doms_cur
= kmalloc(sizeof(cpumask_t
), GFP_KERNEL
);
6507 doms_cur
= &fallback_doms
;
6508 cpus_andnot(*doms_cur
, *cpu_map
, cpu_isolated_map
);
6509 err
= build_sched_domains(doms_cur
);
6510 register_sched_domain_sysctl();
6515 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6517 free_sched_groups(cpu_map
);
6521 * Detach sched domains from a group of cpus specified in cpu_map
6522 * These cpus will now be attached to the NULL domain
6524 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6528 unregister_sched_domain_sysctl();
6530 for_each_cpu_mask(i
, *cpu_map
)
6531 cpu_attach_domain(NULL
, i
);
6532 synchronize_sched();
6533 arch_destroy_sched_domains(cpu_map
);
6537 * Partition sched domains as specified by the 'ndoms_new'
6538 * cpumasks in the array doms_new[] of cpumasks. This compares
6539 * doms_new[] to the current sched domain partitioning, doms_cur[].
6540 * It destroys each deleted domain and builds each new domain.
6542 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
6543 * The masks don't intersect (don't overlap.) We should setup one
6544 * sched domain for each mask. CPUs not in any of the cpumasks will
6545 * not be load balanced. If the same cpumask appears both in the
6546 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6549 * The passed in 'doms_new' should be kmalloc'd. This routine takes
6550 * ownership of it and will kfree it when done with it. If the caller
6551 * failed the kmalloc call, then it can pass in doms_new == NULL,
6552 * and partition_sched_domains() will fallback to the single partition
6555 * Call with hotplug lock held
6557 void partition_sched_domains(int ndoms_new
, cpumask_t
*doms_new
)
6563 /* always unregister in case we don't destroy any domains */
6564 unregister_sched_domain_sysctl();
6566 if (doms_new
== NULL
) {
6568 doms_new
= &fallback_doms
;
6569 cpus_andnot(doms_new
[0], cpu_online_map
, cpu_isolated_map
);
6572 /* Destroy deleted domains */
6573 for (i
= 0; i
< ndoms_cur
; i
++) {
6574 for (j
= 0; j
< ndoms_new
; j
++) {
6575 if (cpus_equal(doms_cur
[i
], doms_new
[j
]))
6578 /* no match - a current sched domain not in new doms_new[] */
6579 detach_destroy_domains(doms_cur
+ i
);
6584 /* Build new domains */
6585 for (i
= 0; i
< ndoms_new
; i
++) {
6586 for (j
= 0; j
< ndoms_cur
; j
++) {
6587 if (cpus_equal(doms_new
[i
], doms_cur
[j
]))
6590 /* no match - add a new doms_new */
6591 build_sched_domains(doms_new
+ i
);
6596 /* Remember the new sched domains */
6597 if (doms_cur
!= &fallback_doms
)
6599 doms_cur
= doms_new
;
6600 ndoms_cur
= ndoms_new
;
6602 register_sched_domain_sysctl();
6607 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6608 static int arch_reinit_sched_domains(void)
6612 mutex_lock(&sched_hotcpu_mutex
);
6613 detach_destroy_domains(&cpu_online_map
);
6614 err
= arch_init_sched_domains(&cpu_online_map
);
6615 mutex_unlock(&sched_hotcpu_mutex
);
6620 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6624 if (buf
[0] != '0' && buf
[0] != '1')
6628 sched_smt_power_savings
= (buf
[0] == '1');
6630 sched_mc_power_savings
= (buf
[0] == '1');
6632 ret
= arch_reinit_sched_domains();
6634 return ret
? ret
: count
;
6637 #ifdef CONFIG_SCHED_MC
6638 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6640 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6642 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6643 const char *buf
, size_t count
)
6645 return sched_power_savings_store(buf
, count
, 0);
6647 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6648 sched_mc_power_savings_store
);
6651 #ifdef CONFIG_SCHED_SMT
6652 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6654 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6656 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6657 const char *buf
, size_t count
)
6659 return sched_power_savings_store(buf
, count
, 1);
6661 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6662 sched_smt_power_savings_store
);
6665 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6669 #ifdef CONFIG_SCHED_SMT
6671 err
= sysfs_create_file(&cls
->kset
.kobj
,
6672 &attr_sched_smt_power_savings
.attr
);
6674 #ifdef CONFIG_SCHED_MC
6675 if (!err
&& mc_capable())
6676 err
= sysfs_create_file(&cls
->kset
.kobj
,
6677 &attr_sched_mc_power_savings
.attr
);
6684 * Force a reinitialization of the sched domains hierarchy. The domains
6685 * and groups cannot be updated in place without racing with the balancing
6686 * code, so we temporarily attach all running cpus to the NULL domain
6687 * which will prevent rebalancing while the sched domains are recalculated.
6689 static int update_sched_domains(struct notifier_block
*nfb
,
6690 unsigned long action
, void *hcpu
)
6693 case CPU_UP_PREPARE
:
6694 case CPU_UP_PREPARE_FROZEN
:
6695 case CPU_DOWN_PREPARE
:
6696 case CPU_DOWN_PREPARE_FROZEN
:
6697 detach_destroy_domains(&cpu_online_map
);
6700 case CPU_UP_CANCELED
:
6701 case CPU_UP_CANCELED_FROZEN
:
6702 case CPU_DOWN_FAILED
:
6703 case CPU_DOWN_FAILED_FROZEN
:
6705 case CPU_ONLINE_FROZEN
:
6707 case CPU_DEAD_FROZEN
:
6709 * Fall through and re-initialise the domains.
6716 /* The hotplug lock is already held by cpu_up/cpu_down */
6717 arch_init_sched_domains(&cpu_online_map
);
6722 void __init
sched_init_smp(void)
6724 cpumask_t non_isolated_cpus
;
6726 mutex_lock(&sched_hotcpu_mutex
);
6727 arch_init_sched_domains(&cpu_online_map
);
6728 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6729 if (cpus_empty(non_isolated_cpus
))
6730 cpu_set(smp_processor_id(), non_isolated_cpus
);
6731 mutex_unlock(&sched_hotcpu_mutex
);
6732 /* XXX: Theoretical race here - CPU may be hotplugged now */
6733 hotcpu_notifier(update_sched_domains
, 0);
6735 /* Move init over to a non-isolated CPU */
6736 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6738 sched_init_granularity();
6741 void __init
sched_init_smp(void)
6743 sched_init_granularity();
6745 #endif /* CONFIG_SMP */
6747 int in_sched_functions(unsigned long addr
)
6749 return in_lock_functions(addr
) ||
6750 (addr
>= (unsigned long)__sched_text_start
6751 && addr
< (unsigned long)__sched_text_end
);
6754 static void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
6756 cfs_rq
->tasks_timeline
= RB_ROOT
;
6757 #ifdef CONFIG_FAIR_GROUP_SCHED
6760 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
6763 void __init
sched_init(void)
6765 int highest_cpu
= 0;
6768 for_each_possible_cpu(i
) {
6769 struct rt_prio_array
*array
;
6773 spin_lock_init(&rq
->lock
);
6774 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6777 init_cfs_rq(&rq
->cfs
, rq
);
6778 #ifdef CONFIG_FAIR_GROUP_SCHED
6779 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6781 struct cfs_rq
*cfs_rq
= &per_cpu(init_cfs_rq
, i
);
6782 struct sched_entity
*se
=
6783 &per_cpu(init_sched_entity
, i
);
6785 init_cfs_rq_p
[i
] = cfs_rq
;
6786 init_cfs_rq(cfs_rq
, rq
);
6787 cfs_rq
->tg
= &init_task_group
;
6788 list_add(&cfs_rq
->leaf_cfs_rq_list
,
6789 &rq
->leaf_cfs_rq_list
);
6791 init_sched_entity_p
[i
] = se
;
6792 se
->cfs_rq
= &rq
->cfs
;
6794 se
->load
.weight
= init_task_group_load
;
6795 se
->load
.inv_weight
=
6796 div64_64(1ULL<<32, init_task_group_load
);
6799 init_task_group
.shares
= init_task_group_load
;
6802 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6803 rq
->cpu_load
[j
] = 0;
6806 rq
->active_balance
= 0;
6807 rq
->next_balance
= jiffies
;
6810 rq
->migration_thread
= NULL
;
6811 INIT_LIST_HEAD(&rq
->migration_queue
);
6813 atomic_set(&rq
->nr_iowait
, 0);
6815 array
= &rq
->rt
.active
;
6816 for (j
= 0; j
< MAX_RT_PRIO
; j
++) {
6817 INIT_LIST_HEAD(array
->queue
+ j
);
6818 __clear_bit(j
, array
->bitmap
);
6821 /* delimiter for bitsearch: */
6822 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
6825 set_load_weight(&init_task
);
6827 #ifdef CONFIG_PREEMPT_NOTIFIERS
6828 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6832 nr_cpu_ids
= highest_cpu
+ 1;
6833 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6836 #ifdef CONFIG_RT_MUTEXES
6837 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6841 * The boot idle thread does lazy MMU switching as well:
6843 atomic_inc(&init_mm
.mm_count
);
6844 enter_lazy_tlb(&init_mm
, current
);
6847 * Make us the idle thread. Technically, schedule() should not be
6848 * called from this thread, however somewhere below it might be,
6849 * but because we are the idle thread, we just pick up running again
6850 * when this runqueue becomes "idle".
6852 init_idle(current
, smp_processor_id());
6854 * During early bootup we pretend to be a normal task:
6856 current
->sched_class
= &fair_sched_class
;
6859 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6860 void __might_sleep(char *file
, int line
)
6863 static unsigned long prev_jiffy
; /* ratelimiting */
6865 if ((in_atomic() || irqs_disabled()) &&
6866 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6867 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6869 prev_jiffy
= jiffies
;
6870 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6871 " context at %s:%d\n", file
, line
);
6872 printk("in_atomic():%d, irqs_disabled():%d\n",
6873 in_atomic(), irqs_disabled());
6874 debug_show_held_locks(current
);
6875 if (irqs_disabled())
6876 print_irqtrace_events(current
);
6881 EXPORT_SYMBOL(__might_sleep
);
6884 #ifdef CONFIG_MAGIC_SYSRQ
6885 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
6888 update_rq_clock(rq
);
6889 on_rq
= p
->se
.on_rq
;
6891 deactivate_task(rq
, p
, 0);
6892 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
6894 activate_task(rq
, p
, 0);
6895 resched_task(rq
->curr
);
6899 void normalize_rt_tasks(void)
6901 struct task_struct
*g
, *p
;
6902 unsigned long flags
;
6905 read_lock_irq(&tasklist_lock
);
6906 do_each_thread(g
, p
) {
6908 * Only normalize user tasks:
6913 p
->se
.exec_start
= 0;
6914 #ifdef CONFIG_SCHEDSTATS
6915 p
->se
.wait_start
= 0;
6916 p
->se
.sleep_start
= 0;
6917 p
->se
.block_start
= 0;
6919 task_rq(p
)->clock
= 0;
6923 * Renice negative nice level userspace
6926 if (TASK_NICE(p
) < 0 && p
->mm
)
6927 set_user_nice(p
, 0);
6931 spin_lock_irqsave(&p
->pi_lock
, flags
);
6932 rq
= __task_rq_lock(p
);
6934 normalize_task(rq
, p
);
6936 __task_rq_unlock(rq
);
6937 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
6938 } while_each_thread(g
, p
);
6940 read_unlock_irq(&tasklist_lock
);
6943 #endif /* CONFIG_MAGIC_SYSRQ */
6947 * These functions are only useful for the IA64 MCA handling.
6949 * They can only be called when the whole system has been
6950 * stopped - every CPU needs to be quiescent, and no scheduling
6951 * activity can take place. Using them for anything else would
6952 * be a serious bug, and as a result, they aren't even visible
6953 * under any other configuration.
6957 * curr_task - return the current task for a given cpu.
6958 * @cpu: the processor in question.
6960 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6962 struct task_struct
*curr_task(int cpu
)
6964 return cpu_curr(cpu
);
6968 * set_curr_task - set the current task for a given cpu.
6969 * @cpu: the processor in question.
6970 * @p: the task pointer to set.
6972 * Description: This function must only be used when non-maskable interrupts
6973 * are serviced on a separate stack. It allows the architecture to switch the
6974 * notion of the current task on a cpu in a non-blocking manner. This function
6975 * must be called with all CPU's synchronized, and interrupts disabled, the
6976 * and caller must save the original value of the current task (see
6977 * curr_task() above) and restore that value before reenabling interrupts and
6978 * re-starting the system.
6980 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6982 void set_curr_task(int cpu
, struct task_struct
*p
)
6989 #ifdef CONFIG_FAIR_GROUP_SCHED
6991 /* allocate runqueue etc for a new task group */
6992 struct task_group
*sched_create_group(void)
6994 struct task_group
*tg
;
6995 struct cfs_rq
*cfs_rq
;
6996 struct sched_entity
*se
;
7000 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
7002 return ERR_PTR(-ENOMEM
);
7004 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * NR_CPUS
, GFP_KERNEL
);
7007 tg
->se
= kzalloc(sizeof(se
) * NR_CPUS
, GFP_KERNEL
);
7011 for_each_possible_cpu(i
) {
7014 cfs_rq
= kmalloc_node(sizeof(struct cfs_rq
), GFP_KERNEL
,
7019 se
= kmalloc_node(sizeof(struct sched_entity
), GFP_KERNEL
,
7024 memset(cfs_rq
, 0, sizeof(struct cfs_rq
));
7025 memset(se
, 0, sizeof(struct sched_entity
));
7027 tg
->cfs_rq
[i
] = cfs_rq
;
7028 init_cfs_rq(cfs_rq
, rq
);
7032 se
->cfs_rq
= &rq
->cfs
;
7034 se
->load
.weight
= NICE_0_LOAD
;
7035 se
->load
.inv_weight
= div64_64(1ULL<<32, NICE_0_LOAD
);
7039 tg
->shares
= NICE_0_LOAD
;
7041 lock_task_group_list();
7042 for_each_possible_cpu(i
) {
7044 cfs_rq
= tg
->cfs_rq
[i
];
7045 list_add_rcu(&cfs_rq
->leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
7047 unlock_task_group_list();
7052 for_each_possible_cpu(i
) {
7054 kfree(tg
->cfs_rq
[i
]);
7062 return ERR_PTR(-ENOMEM
);
7065 /* rcu callback to free various structures associated with a task group */
7066 static void free_sched_group(struct rcu_head
*rhp
)
7068 struct task_group
*tg
= container_of(rhp
, struct task_group
, rcu
);
7069 struct cfs_rq
*cfs_rq
;
7070 struct sched_entity
*se
;
7073 /* now it should be safe to free those cfs_rqs */
7074 for_each_possible_cpu(i
) {
7075 cfs_rq
= tg
->cfs_rq
[i
];
7087 /* Destroy runqueue etc associated with a task group */
7088 void sched_destroy_group(struct task_group
*tg
)
7090 struct cfs_rq
*cfs_rq
= NULL
;
7093 lock_task_group_list();
7094 for_each_possible_cpu(i
) {
7095 cfs_rq
= tg
->cfs_rq
[i
];
7096 list_del_rcu(&cfs_rq
->leaf_cfs_rq_list
);
7098 unlock_task_group_list();
7102 /* wait for possible concurrent references to cfs_rqs complete */
7103 call_rcu(&tg
->rcu
, free_sched_group
);
7106 /* change task's runqueue when it moves between groups.
7107 * The caller of this function should have put the task in its new group
7108 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7109 * reflect its new group.
7111 void sched_move_task(struct task_struct
*tsk
)
7114 unsigned long flags
;
7117 rq
= task_rq_lock(tsk
, &flags
);
7119 if (tsk
->sched_class
!= &fair_sched_class
) {
7120 set_task_cfs_rq(tsk
, task_cpu(tsk
));
7124 update_rq_clock(rq
);
7126 running
= task_current(rq
, tsk
);
7127 on_rq
= tsk
->se
.on_rq
;
7130 dequeue_task(rq
, tsk
, 0);
7131 if (unlikely(running
))
7132 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7135 set_task_cfs_rq(tsk
, task_cpu(tsk
));
7138 if (unlikely(running
))
7139 tsk
->sched_class
->set_curr_task(rq
);
7140 enqueue_task(rq
, tsk
, 0);
7144 task_rq_unlock(rq
, &flags
);
7147 static void set_se_shares(struct sched_entity
*se
, unsigned long shares
)
7149 struct cfs_rq
*cfs_rq
= se
->cfs_rq
;
7150 struct rq
*rq
= cfs_rq
->rq
;
7153 spin_lock_irq(&rq
->lock
);
7157 dequeue_entity(cfs_rq
, se
, 0);
7159 se
->load
.weight
= shares
;
7160 se
->load
.inv_weight
= div64_64((1ULL<<32), shares
);
7163 enqueue_entity(cfs_rq
, se
, 0);
7165 spin_unlock_irq(&rq
->lock
);
7168 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
7173 * A weight of 0 or 1 can cause arithmetics problems.
7174 * (The default weight is 1024 - so there's no practical
7175 * limitation from this.)
7180 lock_task_group_list();
7181 if (tg
->shares
== shares
)
7184 tg
->shares
= shares
;
7185 for_each_possible_cpu(i
)
7186 set_se_shares(tg
->se
[i
], shares
);
7189 unlock_task_group_list();
7193 unsigned long sched_group_shares(struct task_group
*tg
)
7198 #endif /* CONFIG_FAIR_GROUP_SCHED */
7200 #ifdef CONFIG_FAIR_CGROUP_SCHED
7202 /* return corresponding task_group object of a cgroup */
7203 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7205 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7206 struct task_group
, css
);
7209 static struct cgroup_subsys_state
*
7210 cpu_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7212 struct task_group
*tg
;
7214 if (!cgrp
->parent
) {
7215 /* This is early initialization for the top cgroup */
7216 init_task_group
.css
.cgroup
= cgrp
;
7217 return &init_task_group
.css
;
7220 /* we support only 1-level deep hierarchical scheduler atm */
7221 if (cgrp
->parent
->parent
)
7222 return ERR_PTR(-EINVAL
);
7224 tg
= sched_create_group();
7226 return ERR_PTR(-ENOMEM
);
7228 /* Bind the cgroup to task_group object we just created */
7229 tg
->css
.cgroup
= cgrp
;
7235 cpu_cgroup_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7237 struct task_group
*tg
= cgroup_tg(cgrp
);
7239 sched_destroy_group(tg
);
7243 cpu_cgroup_can_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
7244 struct task_struct
*tsk
)
7246 /* We don't support RT-tasks being in separate groups */
7247 if (tsk
->sched_class
!= &fair_sched_class
)
7254 cpu_cgroup_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
7255 struct cgroup
*old_cont
, struct task_struct
*tsk
)
7257 sched_move_task(tsk
);
7260 static int cpu_shares_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
7263 return sched_group_set_shares(cgroup_tg(cgrp
), shareval
);
7266 static u64
cpu_shares_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
7268 struct task_group
*tg
= cgroup_tg(cgrp
);
7270 return (u64
) tg
->shares
;
7273 static struct cftype cpu_files
[] = {
7276 .read_uint
= cpu_shares_read_uint
,
7277 .write_uint
= cpu_shares_write_uint
,
7281 static int cpu_cgroup_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
7283 return cgroup_add_files(cont
, ss
, cpu_files
, ARRAY_SIZE(cpu_files
));
7286 struct cgroup_subsys cpu_cgroup_subsys
= {
7288 .create
= cpu_cgroup_create
,
7289 .destroy
= cpu_cgroup_destroy
,
7290 .can_attach
= cpu_cgroup_can_attach
,
7291 .attach
= cpu_cgroup_attach
,
7292 .populate
= cpu_cgroup_populate
,
7293 .subsys_id
= cpu_cgroup_subsys_id
,
7297 #endif /* CONFIG_FAIR_CGROUP_SCHED */
7299 #ifdef CONFIG_CGROUP_CPUACCT
7302 * CPU accounting code for task groups.
7304 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
7305 * (balbir@in.ibm.com).
7308 /* track cpu usage of a group of tasks */
7310 struct cgroup_subsys_state css
;
7311 /* cpuusage holds pointer to a u64-type object on every cpu */
7315 struct cgroup_subsys cpuacct_subsys
;
7317 /* return cpu accounting group corresponding to this container */
7318 static inline struct cpuacct
*cgroup_ca(struct cgroup
*cont
)
7320 return container_of(cgroup_subsys_state(cont
, cpuacct_subsys_id
),
7321 struct cpuacct
, css
);
7324 /* return cpu accounting group to which this task belongs */
7325 static inline struct cpuacct
*task_ca(struct task_struct
*tsk
)
7327 return container_of(task_subsys_state(tsk
, cpuacct_subsys_id
),
7328 struct cpuacct
, css
);
7331 /* create a new cpu accounting group */
7332 static struct cgroup_subsys_state
*cpuacct_create(
7333 struct cgroup_subsys
*ss
, struct cgroup
*cont
)
7335 struct cpuacct
*ca
= kzalloc(sizeof(*ca
), GFP_KERNEL
);
7338 return ERR_PTR(-ENOMEM
);
7340 ca
->cpuusage
= alloc_percpu(u64
);
7341 if (!ca
->cpuusage
) {
7343 return ERR_PTR(-ENOMEM
);
7349 /* destroy an existing cpu accounting group */
7351 cpuacct_destroy(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
7353 struct cpuacct
*ca
= cgroup_ca(cont
);
7355 free_percpu(ca
->cpuusage
);
7359 /* return total cpu usage (in nanoseconds) of a group */
7360 static u64
cpuusage_read(struct cgroup
*cont
, struct cftype
*cft
)
7362 struct cpuacct
*ca
= cgroup_ca(cont
);
7363 u64 totalcpuusage
= 0;
7366 for_each_possible_cpu(i
) {
7367 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, i
);
7370 * Take rq->lock to make 64-bit addition safe on 32-bit
7373 spin_lock_irq(&cpu_rq(i
)->lock
);
7374 totalcpuusage
+= *cpuusage
;
7375 spin_unlock_irq(&cpu_rq(i
)->lock
);
7378 return totalcpuusage
;
7381 static struct cftype files
[] = {
7384 .read_uint
= cpuusage_read
,
7388 static int cpuacct_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
7390 return cgroup_add_files(cont
, ss
, files
, ARRAY_SIZE(files
));
7394 * charge this task's execution time to its accounting group.
7396 * called with rq->lock held.
7398 static void cpuacct_charge(struct task_struct
*tsk
, u64 cputime
)
7402 if (!cpuacct_subsys
.active
)
7407 u64
*cpuusage
= percpu_ptr(ca
->cpuusage
, task_cpu(tsk
));
7409 *cpuusage
+= cputime
;
7413 struct cgroup_subsys cpuacct_subsys
= {
7415 .create
= cpuacct_create
,
7416 .destroy
= cpuacct_destroy
,
7417 .populate
= cpuacct_populate
,
7418 .subsys_id
= cpuacct_subsys_id
,
7420 #endif /* CONFIG_CGROUP_CPUACCT */