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
;
172 /* spinlock to serialize modification to shares */
177 /* Default task group's sched entity on each cpu */
178 static DEFINE_PER_CPU(struct sched_entity
, init_sched_entity
);
179 /* Default task group's cfs_rq on each cpu */
180 static DEFINE_PER_CPU(struct cfs_rq
, init_cfs_rq
) ____cacheline_aligned_in_smp
;
182 static struct sched_entity
*init_sched_entity_p
[NR_CPUS
];
183 static struct cfs_rq
*init_cfs_rq_p
[NR_CPUS
];
185 /* Default task group.
186 * Every task in system belong to this group at bootup.
188 struct task_group init_task_group
= {
189 .se
= init_sched_entity_p
,
190 .cfs_rq
= init_cfs_rq_p
,
193 #ifdef CONFIG_FAIR_USER_SCHED
194 # define INIT_TASK_GRP_LOAD 2*NICE_0_LOAD
196 # define INIT_TASK_GRP_LOAD NICE_0_LOAD
199 static int init_task_group_load
= INIT_TASK_GRP_LOAD
;
201 /* return group to which a task belongs */
202 static inline struct task_group
*task_group(struct task_struct
*p
)
204 struct task_group
*tg
;
206 #ifdef CONFIG_FAIR_USER_SCHED
208 #elif defined(CONFIG_FAIR_CGROUP_SCHED)
209 tg
= container_of(task_subsys_state(p
, cpu_cgroup_subsys_id
),
210 struct task_group
, css
);
212 tg
= &init_task_group
;
218 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
219 static inline void set_task_cfs_rq(struct task_struct
*p
)
221 p
->se
.cfs_rq
= task_group(p
)->cfs_rq
[task_cpu(p
)];
222 p
->se
.parent
= task_group(p
)->se
[task_cpu(p
)];
227 static inline void set_task_cfs_rq(struct task_struct
*p
) { }
229 #endif /* CONFIG_FAIR_GROUP_SCHED */
231 /* CFS-related fields in a runqueue */
233 struct load_weight load
;
234 unsigned long nr_running
;
239 struct rb_root tasks_timeline
;
240 struct rb_node
*rb_leftmost
;
241 struct rb_node
*rb_load_balance_curr
;
242 /* 'curr' points to currently running entity on this cfs_rq.
243 * It is set to NULL otherwise (i.e when none are currently running).
245 struct sched_entity
*curr
;
247 unsigned long nr_spread_over
;
249 #ifdef CONFIG_FAIR_GROUP_SCHED
250 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
252 /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
253 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
254 * (like users, containers etc.)
256 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
257 * list is used during load balance.
259 struct list_head leaf_cfs_rq_list
; /* Better name : task_cfs_rq_list? */
260 struct task_group
*tg
; /* group that "owns" this runqueue */
264 /* Real-Time classes' related field in a runqueue: */
266 struct rt_prio_array active
;
267 int rt_load_balance_idx
;
268 struct list_head
*rt_load_balance_head
, *rt_load_balance_curr
;
272 * This is the main, per-CPU runqueue data structure.
274 * Locking rule: those places that want to lock multiple runqueues
275 * (such as the load balancing or the thread migration code), lock
276 * acquire operations must be ordered by ascending &runqueue.
283 * nr_running and cpu_load should be in the same cacheline because
284 * remote CPUs use both these fields when doing load calculation.
286 unsigned long nr_running
;
287 #define CPU_LOAD_IDX_MAX 5
288 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
289 unsigned char idle_at_tick
;
291 unsigned char in_nohz_recently
;
293 /* capture load from *all* tasks on this cpu: */
294 struct load_weight load
;
295 unsigned long nr_load_updates
;
299 #ifdef CONFIG_FAIR_GROUP_SCHED
300 /* list of leaf cfs_rq on this cpu: */
301 struct list_head leaf_cfs_rq_list
;
306 * This is part of a global counter where only the total sum
307 * over all CPUs matters. A task can increase this counter on
308 * one CPU and if it got migrated afterwards it may decrease
309 * it on another CPU. Always updated under the runqueue lock:
311 unsigned long nr_uninterruptible
;
313 struct task_struct
*curr
, *idle
;
314 unsigned long next_balance
;
315 struct mm_struct
*prev_mm
;
317 u64 clock
, prev_clock_raw
;
320 unsigned int clock_warps
, clock_overflows
;
322 unsigned int clock_deep_idle_events
;
328 struct sched_domain
*sd
;
330 /* For active balancing */
333 /* cpu of this runqueue: */
336 struct task_struct
*migration_thread
;
337 struct list_head migration_queue
;
340 #ifdef CONFIG_SCHEDSTATS
342 struct sched_info rq_sched_info
;
344 /* sys_sched_yield() stats */
345 unsigned int yld_exp_empty
;
346 unsigned int yld_act_empty
;
347 unsigned int yld_both_empty
;
348 unsigned int yld_count
;
350 /* schedule() stats */
351 unsigned int sched_switch
;
352 unsigned int sched_count
;
353 unsigned int sched_goidle
;
355 /* try_to_wake_up() stats */
356 unsigned int ttwu_count
;
357 unsigned int ttwu_local
;
360 unsigned int bkl_count
;
362 struct lock_class_key rq_lock_key
;
365 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
366 static DEFINE_MUTEX(sched_hotcpu_mutex
);
368 static inline void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
)
370 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
);
373 static inline int cpu_of(struct rq
*rq
)
383 * Update the per-runqueue clock, as finegrained as the platform can give
384 * us, but without assuming monotonicity, etc.:
386 static void __update_rq_clock(struct rq
*rq
)
388 u64 prev_raw
= rq
->prev_clock_raw
;
389 u64 now
= sched_clock();
390 s64 delta
= now
- prev_raw
;
391 u64 clock
= rq
->clock
;
393 #ifdef CONFIG_SCHED_DEBUG
394 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
397 * Protect against sched_clock() occasionally going backwards:
399 if (unlikely(delta
< 0)) {
404 * Catch too large forward jumps too:
406 if (unlikely(clock
+ delta
> rq
->tick_timestamp
+ TICK_NSEC
)) {
407 if (clock
< rq
->tick_timestamp
+ TICK_NSEC
)
408 clock
= rq
->tick_timestamp
+ TICK_NSEC
;
411 rq
->clock_overflows
++;
413 if (unlikely(delta
> rq
->clock_max_delta
))
414 rq
->clock_max_delta
= delta
;
419 rq
->prev_clock_raw
= now
;
423 static void update_rq_clock(struct rq
*rq
)
425 if (likely(smp_processor_id() == cpu_of(rq
)))
426 __update_rq_clock(rq
);
430 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
431 * See detach_destroy_domains: synchronize_sched for details.
433 * The domain tree of any CPU may only be accessed from within
434 * preempt-disabled sections.
436 #define for_each_domain(cpu, __sd) \
437 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
439 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
440 #define this_rq() (&__get_cpu_var(runqueues))
441 #define task_rq(p) cpu_rq(task_cpu(p))
442 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
445 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
447 #ifdef CONFIG_SCHED_DEBUG
448 # define const_debug __read_mostly
450 # define const_debug static const
454 * Debugging: various feature bits
457 SCHED_FEAT_NEW_FAIR_SLEEPERS
= 1,
458 SCHED_FEAT_START_DEBIT
= 2,
459 SCHED_FEAT_TREE_AVG
= 4,
460 SCHED_FEAT_APPROX_AVG
= 8,
461 SCHED_FEAT_WAKEUP_PREEMPT
= 16,
464 const_debug
unsigned int sysctl_sched_features
=
465 SCHED_FEAT_NEW_FAIR_SLEEPERS
* 1 |
466 SCHED_FEAT_START_DEBIT
* 1 |
467 SCHED_FEAT_TREE_AVG
* 0 |
468 SCHED_FEAT_APPROX_AVG
* 0 |
469 SCHED_FEAT_WAKEUP_PREEMPT
* 1;
471 #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x)
474 * Number of tasks to iterate in a single balance run.
475 * Limited because this is done with IRQs disabled.
477 const_debug
unsigned int sysctl_sched_nr_migrate
= 32;
480 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
481 * clock constructed from sched_clock():
483 unsigned long long cpu_clock(int cpu
)
485 unsigned long long now
;
489 local_irq_save(flags
);
493 local_irq_restore(flags
);
497 EXPORT_SYMBOL_GPL(cpu_clock
);
499 #ifndef prepare_arch_switch
500 # define prepare_arch_switch(next) do { } while (0)
502 #ifndef finish_arch_switch
503 # define finish_arch_switch(prev) do { } while (0)
506 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
507 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
509 return rq
->curr
== p
;
512 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
516 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
518 #ifdef CONFIG_DEBUG_SPINLOCK
519 /* this is a valid case when another task releases the spinlock */
520 rq
->lock
.owner
= current
;
523 * If we are tracking spinlock dependencies then we have to
524 * fix up the runqueue lock - which gets 'carried over' from
527 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
529 spin_unlock_irq(&rq
->lock
);
532 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
533 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
538 return rq
->curr
== p
;
542 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
546 * We can optimise this out completely for !SMP, because the
547 * SMP rebalancing from interrupt is the only thing that cares
552 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
553 spin_unlock_irq(&rq
->lock
);
555 spin_unlock(&rq
->lock
);
559 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
563 * After ->oncpu is cleared, the task can be moved to a different CPU.
564 * We must ensure this doesn't happen until the switch is completely
570 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
574 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
577 * __task_rq_lock - lock the runqueue a given task resides on.
578 * Must be called interrupts disabled.
580 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
584 struct rq
*rq
= task_rq(p
);
585 spin_lock(&rq
->lock
);
586 if (likely(rq
== task_rq(p
)))
588 spin_unlock(&rq
->lock
);
593 * task_rq_lock - lock the runqueue a given task resides on and disable
594 * interrupts. Note the ordering: we can safely lookup the task_rq without
595 * explicitly disabling preemption.
597 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
603 local_irq_save(*flags
);
605 spin_lock(&rq
->lock
);
606 if (likely(rq
== task_rq(p
)))
608 spin_unlock_irqrestore(&rq
->lock
, *flags
);
612 static void __task_rq_unlock(struct rq
*rq
)
615 spin_unlock(&rq
->lock
);
618 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
621 spin_unlock_irqrestore(&rq
->lock
, *flags
);
625 * this_rq_lock - lock this runqueue and disable interrupts.
627 static struct rq
*this_rq_lock(void)
634 spin_lock(&rq
->lock
);
640 * We are going deep-idle (irqs are disabled):
642 void sched_clock_idle_sleep_event(void)
644 struct rq
*rq
= cpu_rq(smp_processor_id());
646 spin_lock(&rq
->lock
);
647 __update_rq_clock(rq
);
648 spin_unlock(&rq
->lock
);
649 rq
->clock_deep_idle_events
++;
651 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
654 * We just idled delta nanoseconds (called with irqs disabled):
656 void sched_clock_idle_wakeup_event(u64 delta_ns
)
658 struct rq
*rq
= cpu_rq(smp_processor_id());
659 u64 now
= sched_clock();
661 rq
->idle_clock
+= delta_ns
;
663 * Override the previous timestamp and ignore all
664 * sched_clock() deltas that occured while we idled,
665 * and use the PM-provided delta_ns to advance the
668 spin_lock(&rq
->lock
);
669 rq
->prev_clock_raw
= now
;
670 rq
->clock
+= delta_ns
;
671 spin_unlock(&rq
->lock
);
673 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
676 * resched_task - mark a task 'to be rescheduled now'.
678 * On UP this means the setting of the need_resched flag, on SMP it
679 * might also involve a cross-CPU call to trigger the scheduler on
684 #ifndef tsk_is_polling
685 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
688 static void resched_task(struct task_struct
*p
)
692 assert_spin_locked(&task_rq(p
)->lock
);
694 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
697 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
700 if (cpu
== smp_processor_id())
703 /* NEED_RESCHED must be visible before we test polling */
705 if (!tsk_is_polling(p
))
706 smp_send_reschedule(cpu
);
709 static void resched_cpu(int cpu
)
711 struct rq
*rq
= cpu_rq(cpu
);
714 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
716 resched_task(cpu_curr(cpu
));
717 spin_unlock_irqrestore(&rq
->lock
, flags
);
720 static inline void resched_task(struct task_struct
*p
)
722 assert_spin_locked(&task_rq(p
)->lock
);
723 set_tsk_need_resched(p
);
727 #if BITS_PER_LONG == 32
728 # define WMULT_CONST (~0UL)
730 # define WMULT_CONST (1UL << 32)
733 #define WMULT_SHIFT 32
736 * Shift right and round:
738 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
741 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
742 struct load_weight
*lw
)
746 if (unlikely(!lw
->inv_weight
))
747 lw
->inv_weight
= (WMULT_CONST
- lw
->weight
/2) / lw
->weight
+ 1;
749 tmp
= (u64
)delta_exec
* weight
;
751 * Check whether we'd overflow the 64-bit multiplication:
753 if (unlikely(tmp
> WMULT_CONST
))
754 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
757 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
759 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
762 static inline unsigned long
763 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
765 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
768 static inline void update_load_add(struct load_weight
*lw
, unsigned long inc
)
773 static inline void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
779 * To aid in avoiding the subversion of "niceness" due to uneven distribution
780 * of tasks with abnormal "nice" values across CPUs the contribution that
781 * each task makes to its run queue's load is weighted according to its
782 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
783 * scaled version of the new time slice allocation that they receive on time
787 #define WEIGHT_IDLEPRIO 2
788 #define WMULT_IDLEPRIO (1 << 31)
791 * Nice levels are multiplicative, with a gentle 10% change for every
792 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
793 * nice 1, it will get ~10% less CPU time than another CPU-bound task
794 * that remained on nice 0.
796 * The "10% effect" is relative and cumulative: from _any_ nice level,
797 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
798 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
799 * If a task goes up by ~10% and another task goes down by ~10% then
800 * the relative distance between them is ~25%.)
802 static const int prio_to_weight
[40] = {
803 /* -20 */ 88761, 71755, 56483, 46273, 36291,
804 /* -15 */ 29154, 23254, 18705, 14949, 11916,
805 /* -10 */ 9548, 7620, 6100, 4904, 3906,
806 /* -5 */ 3121, 2501, 1991, 1586, 1277,
807 /* 0 */ 1024, 820, 655, 526, 423,
808 /* 5 */ 335, 272, 215, 172, 137,
809 /* 10 */ 110, 87, 70, 56, 45,
810 /* 15 */ 36, 29, 23, 18, 15,
814 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
816 * In cases where the weight does not change often, we can use the
817 * precalculated inverse to speed up arithmetics by turning divisions
818 * into multiplications:
820 static const u32 prio_to_wmult
[40] = {
821 /* -20 */ 48388, 59856, 76040, 92818, 118348,
822 /* -15 */ 147320, 184698, 229616, 287308, 360437,
823 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
824 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
825 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
826 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
827 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
828 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
831 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
834 * runqueue iterator, to support SMP load-balancing between different
835 * scheduling classes, without having to expose their internal data
836 * structures to the load-balancing proper:
840 struct task_struct
*(*start
)(void *);
841 struct task_struct
*(*next
)(void *);
846 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
847 unsigned long max_load_move
, struct sched_domain
*sd
,
848 enum cpu_idle_type idle
, int *all_pinned
,
849 int *this_best_prio
, struct rq_iterator
*iterator
);
852 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
853 struct sched_domain
*sd
, enum cpu_idle_type idle
,
854 struct rq_iterator
*iterator
);
857 #include "sched_stats.h"
858 #include "sched_idletask.c"
859 #include "sched_fair.c"
860 #include "sched_rt.c"
861 #ifdef CONFIG_SCHED_DEBUG
862 # include "sched_debug.c"
865 #define sched_class_highest (&rt_sched_class)
868 * Update delta_exec, delta_fair fields for rq.
870 * delta_fair clock advances at a rate inversely proportional to
871 * total load (rq->load.weight) on the runqueue, while
872 * delta_exec advances at the same rate as wall-clock (provided
875 * delta_exec / delta_fair is a measure of the (smoothened) load on this
876 * runqueue over any given interval. This (smoothened) load is used
877 * during load balance.
879 * This function is called /before/ updating rq->load
880 * and when switching tasks.
882 static inline void inc_load(struct rq
*rq
, const struct task_struct
*p
)
884 update_load_add(&rq
->load
, p
->se
.load
.weight
);
887 static inline void dec_load(struct rq
*rq
, const struct task_struct
*p
)
889 update_load_sub(&rq
->load
, p
->se
.load
.weight
);
892 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
898 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
904 static void set_load_weight(struct task_struct
*p
)
906 if (task_has_rt_policy(p
)) {
907 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
908 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
913 * SCHED_IDLE tasks get minimal weight:
915 if (p
->policy
== SCHED_IDLE
) {
916 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
917 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
921 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
922 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
925 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
927 sched_info_queued(p
);
928 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
932 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
934 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
939 * __normal_prio - return the priority that is based on the static prio
941 static inline int __normal_prio(struct task_struct
*p
)
943 return p
->static_prio
;
947 * Calculate the expected normal priority: i.e. priority
948 * without taking RT-inheritance into account. Might be
949 * boosted by interactivity modifiers. Changes upon fork,
950 * setprio syscalls, and whenever the interactivity
951 * estimator recalculates.
953 static inline int normal_prio(struct task_struct
*p
)
957 if (task_has_rt_policy(p
))
958 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
960 prio
= __normal_prio(p
);
965 * Calculate the current priority, i.e. the priority
966 * taken into account by the scheduler. This value might
967 * be boosted by RT tasks, or might be boosted by
968 * interactivity modifiers. Will be RT if the task got
969 * RT-boosted. If not then it returns p->normal_prio.
971 static int effective_prio(struct task_struct
*p
)
973 p
->normal_prio
= normal_prio(p
);
975 * If we are RT tasks or we were boosted to RT priority,
976 * keep the priority unchanged. Otherwise, update priority
977 * to the normal priority:
979 if (!rt_prio(p
->prio
))
980 return p
->normal_prio
;
985 * activate_task - move a task to the runqueue.
987 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
989 if (p
->state
== TASK_UNINTERRUPTIBLE
)
990 rq
->nr_uninterruptible
--;
992 enqueue_task(rq
, p
, wakeup
);
993 inc_nr_running(p
, rq
);
997 * deactivate_task - remove a task from the runqueue.
999 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
1001 if (p
->state
== TASK_UNINTERRUPTIBLE
)
1002 rq
->nr_uninterruptible
++;
1004 dequeue_task(rq
, p
, sleep
);
1005 dec_nr_running(p
, rq
);
1009 * task_curr - is this task currently executing on a CPU?
1010 * @p: the task in question.
1012 inline int task_curr(const struct task_struct
*p
)
1014 return cpu_curr(task_cpu(p
)) == p
;
1017 /* Used instead of source_load when we know the type == 0 */
1018 unsigned long weighted_cpuload(const int cpu
)
1020 return cpu_rq(cpu
)->load
.weight
;
1023 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
1026 task_thread_info(p
)->cpu
= cpu
;
1034 * Is this task likely cache-hot:
1037 task_hot(struct task_struct
*p
, u64 now
, struct sched_domain
*sd
)
1041 if (p
->sched_class
!= &fair_sched_class
)
1044 if (sysctl_sched_migration_cost
== -1)
1046 if (sysctl_sched_migration_cost
== 0)
1049 delta
= now
- p
->se
.exec_start
;
1051 return delta
< (s64
)sysctl_sched_migration_cost
;
1055 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1057 int old_cpu
= task_cpu(p
);
1058 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
1059 struct cfs_rq
*old_cfsrq
= task_cfs_rq(p
),
1060 *new_cfsrq
= cpu_cfs_rq(old_cfsrq
, new_cpu
);
1063 clock_offset
= old_rq
->clock
- new_rq
->clock
;
1065 #ifdef CONFIG_SCHEDSTATS
1066 if (p
->se
.wait_start
)
1067 p
->se
.wait_start
-= clock_offset
;
1068 if (p
->se
.sleep_start
)
1069 p
->se
.sleep_start
-= clock_offset
;
1070 if (p
->se
.block_start
)
1071 p
->se
.block_start
-= clock_offset
;
1072 if (old_cpu
!= new_cpu
) {
1073 schedstat_inc(p
, se
.nr_migrations
);
1074 if (task_hot(p
, old_rq
->clock
, NULL
))
1075 schedstat_inc(p
, se
.nr_forced2_migrations
);
1078 p
->se
.vruntime
-= old_cfsrq
->min_vruntime
-
1079 new_cfsrq
->min_vruntime
;
1081 __set_task_cpu(p
, new_cpu
);
1084 struct migration_req
{
1085 struct list_head list
;
1087 struct task_struct
*task
;
1090 struct completion done
;
1094 * The task's runqueue lock must be held.
1095 * Returns true if you have to wait for migration thread.
1098 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1100 struct rq
*rq
= task_rq(p
);
1103 * If the task is not on a runqueue (and not running), then
1104 * it is sufficient to simply update the task's cpu field.
1106 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1107 set_task_cpu(p
, dest_cpu
);
1111 init_completion(&req
->done
);
1113 req
->dest_cpu
= dest_cpu
;
1114 list_add(&req
->list
, &rq
->migration_queue
);
1120 * wait_task_inactive - wait for a thread to unschedule.
1122 * The caller must ensure that the task *will* unschedule sometime soon,
1123 * else this function might spin for a *long* time. This function can't
1124 * be called with interrupts off, or it may introduce deadlock with
1125 * smp_call_function() if an IPI is sent by the same process we are
1126 * waiting to become inactive.
1128 void wait_task_inactive(struct task_struct
*p
)
1130 unsigned long flags
;
1136 * We do the initial early heuristics without holding
1137 * any task-queue locks at all. We'll only try to get
1138 * the runqueue lock when things look like they will
1144 * If the task is actively running on another CPU
1145 * still, just relax and busy-wait without holding
1148 * NOTE! Since we don't hold any locks, it's not
1149 * even sure that "rq" stays as the right runqueue!
1150 * But we don't care, since "task_running()" will
1151 * return false if the runqueue has changed and p
1152 * is actually now running somewhere else!
1154 while (task_running(rq
, p
))
1158 * Ok, time to look more closely! We need the rq
1159 * lock now, to be *sure*. If we're wrong, we'll
1160 * just go back and repeat.
1162 rq
= task_rq_lock(p
, &flags
);
1163 running
= task_running(rq
, p
);
1164 on_rq
= p
->se
.on_rq
;
1165 task_rq_unlock(rq
, &flags
);
1168 * Was it really running after all now that we
1169 * checked with the proper locks actually held?
1171 * Oops. Go back and try again..
1173 if (unlikely(running
)) {
1179 * It's not enough that it's not actively running,
1180 * it must be off the runqueue _entirely_, and not
1183 * So if it wa still runnable (but just not actively
1184 * running right now), it's preempted, and we should
1185 * yield - it could be a while.
1187 if (unlikely(on_rq
)) {
1188 schedule_timeout_uninterruptible(1);
1193 * Ahh, all good. It wasn't running, and it wasn't
1194 * runnable, which means that it will never become
1195 * running in the future either. We're all done!
1202 * kick_process - kick a running thread to enter/exit the kernel
1203 * @p: the to-be-kicked thread
1205 * Cause a process which is running on another CPU to enter
1206 * kernel-mode, without any delay. (to get signals handled.)
1208 * NOTE: this function doesnt have to take the runqueue lock,
1209 * because all it wants to ensure is that the remote task enters
1210 * the kernel. If the IPI races and the task has been migrated
1211 * to another CPU then no harm is done and the purpose has been
1214 void kick_process(struct task_struct
*p
)
1220 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1221 smp_send_reschedule(cpu
);
1226 * Return a low guess at the load of a migration-source cpu weighted
1227 * according to the scheduling class and "nice" value.
1229 * We want to under-estimate the load of migration sources, to
1230 * balance conservatively.
1232 static unsigned long source_load(int cpu
, int type
)
1234 struct rq
*rq
= cpu_rq(cpu
);
1235 unsigned long total
= weighted_cpuload(cpu
);
1240 return min(rq
->cpu_load
[type
-1], total
);
1244 * Return a high guess at the load of a migration-target cpu weighted
1245 * according to the scheduling class and "nice" value.
1247 static unsigned long target_load(int cpu
, int type
)
1249 struct rq
*rq
= cpu_rq(cpu
);
1250 unsigned long total
= weighted_cpuload(cpu
);
1255 return max(rq
->cpu_load
[type
-1], total
);
1259 * Return the average load per task on the cpu's run queue
1261 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1263 struct rq
*rq
= cpu_rq(cpu
);
1264 unsigned long total
= weighted_cpuload(cpu
);
1265 unsigned long n
= rq
->nr_running
;
1267 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1271 * find_idlest_group finds and returns the least busy CPU group within the
1274 static struct sched_group
*
1275 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1277 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1278 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1279 int load_idx
= sd
->forkexec_idx
;
1280 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1283 unsigned long load
, avg_load
;
1287 /* Skip over this group if it has no CPUs allowed */
1288 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1291 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1293 /* Tally up the load of all CPUs in the group */
1296 for_each_cpu_mask(i
, group
->cpumask
) {
1297 /* Bias balancing toward cpus of our domain */
1299 load
= source_load(i
, load_idx
);
1301 load
= target_load(i
, load_idx
);
1306 /* Adjust by relative CPU power of the group */
1307 avg_load
= sg_div_cpu_power(group
,
1308 avg_load
* SCHED_LOAD_SCALE
);
1311 this_load
= avg_load
;
1313 } else if (avg_load
< min_load
) {
1314 min_load
= avg_load
;
1317 } while (group
= group
->next
, group
!= sd
->groups
);
1319 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1325 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1328 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1331 unsigned long load
, min_load
= ULONG_MAX
;
1335 /* Traverse only the allowed CPUs */
1336 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1338 for_each_cpu_mask(i
, tmp
) {
1339 load
= weighted_cpuload(i
);
1341 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1351 * sched_balance_self: balance the current task (running on cpu) in domains
1352 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1355 * Balance, ie. select the least loaded group.
1357 * Returns the target CPU number, or the same CPU if no balancing is needed.
1359 * preempt must be disabled.
1361 static int sched_balance_self(int cpu
, int flag
)
1363 struct task_struct
*t
= current
;
1364 struct sched_domain
*tmp
, *sd
= NULL
;
1366 for_each_domain(cpu
, tmp
) {
1368 * If power savings logic is enabled for a domain, stop there.
1370 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1372 if (tmp
->flags
& flag
)
1378 struct sched_group
*group
;
1379 int new_cpu
, weight
;
1381 if (!(sd
->flags
& flag
)) {
1387 group
= find_idlest_group(sd
, t
, cpu
);
1393 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1394 if (new_cpu
== -1 || new_cpu
== cpu
) {
1395 /* Now try balancing at a lower domain level of cpu */
1400 /* Now try balancing at a lower domain level of new_cpu */
1403 weight
= cpus_weight(span
);
1404 for_each_domain(cpu
, tmp
) {
1405 if (weight
<= cpus_weight(tmp
->span
))
1407 if (tmp
->flags
& flag
)
1410 /* while loop will break here if sd == NULL */
1416 #endif /* CONFIG_SMP */
1419 * wake_idle() will wake a task on an idle cpu if task->cpu is
1420 * not idle and an idle cpu is available. The span of cpus to
1421 * search starts with cpus closest then further out as needed,
1422 * so we always favor a closer, idle cpu.
1424 * Returns the CPU we should wake onto.
1426 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1427 static int wake_idle(int cpu
, struct task_struct
*p
)
1430 struct sched_domain
*sd
;
1434 * If it is idle, then it is the best cpu to run this task.
1436 * This cpu is also the best, if it has more than one task already.
1437 * Siblings must be also busy(in most cases) as they didn't already
1438 * pickup the extra load from this cpu and hence we need not check
1439 * sibling runqueue info. This will avoid the checks and cache miss
1440 * penalities associated with that.
1442 if (idle_cpu(cpu
) || cpu_rq(cpu
)->nr_running
> 1)
1445 for_each_domain(cpu
, sd
) {
1446 if (sd
->flags
& SD_WAKE_IDLE
) {
1447 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1448 for_each_cpu_mask(i
, tmp
) {
1450 if (i
!= task_cpu(p
)) {
1452 se
.nr_wakeups_idle
);
1464 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1471 * try_to_wake_up - wake up a thread
1472 * @p: the to-be-woken-up thread
1473 * @state: the mask of task states that can be woken
1474 * @sync: do a synchronous wakeup?
1476 * Put it on the run-queue if it's not already there. The "current"
1477 * thread is always on the run-queue (except when the actual
1478 * re-schedule is in progress), and as such you're allowed to do
1479 * the simpler "current->state = TASK_RUNNING" to mark yourself
1480 * runnable without the overhead of this.
1482 * returns failure only if the task is already active.
1484 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1486 int cpu
, orig_cpu
, this_cpu
, success
= 0;
1487 unsigned long flags
;
1491 struct sched_domain
*sd
, *this_sd
= NULL
;
1492 unsigned long load
, this_load
;
1496 rq
= task_rq_lock(p
, &flags
);
1497 old_state
= p
->state
;
1498 if (!(old_state
& state
))
1506 this_cpu
= smp_processor_id();
1509 if (unlikely(task_running(rq
, p
)))
1514 schedstat_inc(rq
, ttwu_count
);
1515 if (cpu
== this_cpu
) {
1516 schedstat_inc(rq
, ttwu_local
);
1520 for_each_domain(this_cpu
, sd
) {
1521 if (cpu_isset(cpu
, sd
->span
)) {
1522 schedstat_inc(sd
, ttwu_wake_remote
);
1528 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1532 * Check for affine wakeup and passive balancing possibilities.
1535 int idx
= this_sd
->wake_idx
;
1536 unsigned int imbalance
;
1538 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1540 load
= source_load(cpu
, idx
);
1541 this_load
= target_load(this_cpu
, idx
);
1543 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1545 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1546 unsigned long tl
= this_load
;
1547 unsigned long tl_per_task
;
1550 * Attract cache-cold tasks on sync wakeups:
1552 if (sync
&& !task_hot(p
, rq
->clock
, this_sd
))
1555 schedstat_inc(p
, se
.nr_wakeups_affine_attempts
);
1556 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1559 * If sync wakeup then subtract the (maximum possible)
1560 * effect of the currently running task from the load
1561 * of the current CPU:
1564 tl
-= current
->se
.load
.weight
;
1567 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1568 100*(tl
+ p
->se
.load
.weight
) <= imbalance
*load
) {
1570 * This domain has SD_WAKE_AFFINE and
1571 * p is cache cold in this domain, and
1572 * there is no bad imbalance.
1574 schedstat_inc(this_sd
, ttwu_move_affine
);
1575 schedstat_inc(p
, se
.nr_wakeups_affine
);
1581 * Start passive balancing when half the imbalance_pct
1584 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1585 if (imbalance
*this_load
<= 100*load
) {
1586 schedstat_inc(this_sd
, ttwu_move_balance
);
1587 schedstat_inc(p
, se
.nr_wakeups_passive
);
1593 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1595 new_cpu
= wake_idle(new_cpu
, p
);
1596 if (new_cpu
!= cpu
) {
1597 set_task_cpu(p
, new_cpu
);
1598 task_rq_unlock(rq
, &flags
);
1599 /* might preempt at this point */
1600 rq
= task_rq_lock(p
, &flags
);
1601 old_state
= p
->state
;
1602 if (!(old_state
& state
))
1607 this_cpu
= smp_processor_id();
1612 #endif /* CONFIG_SMP */
1613 schedstat_inc(p
, se
.nr_wakeups
);
1615 schedstat_inc(p
, se
.nr_wakeups_sync
);
1616 if (orig_cpu
!= cpu
)
1617 schedstat_inc(p
, se
.nr_wakeups_migrate
);
1618 if (cpu
== this_cpu
)
1619 schedstat_inc(p
, se
.nr_wakeups_local
);
1621 schedstat_inc(p
, se
.nr_wakeups_remote
);
1622 update_rq_clock(rq
);
1623 activate_task(rq
, p
, 1);
1624 check_preempt_curr(rq
, p
);
1628 p
->state
= TASK_RUNNING
;
1630 task_rq_unlock(rq
, &flags
);
1635 int fastcall
wake_up_process(struct task_struct
*p
)
1637 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1638 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1640 EXPORT_SYMBOL(wake_up_process
);
1642 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1644 return try_to_wake_up(p
, state
, 0);
1648 * Perform scheduler related setup for a newly forked process p.
1649 * p is forked by current.
1651 * __sched_fork() is basic setup used by init_idle() too:
1653 static void __sched_fork(struct task_struct
*p
)
1655 p
->se
.exec_start
= 0;
1656 p
->se
.sum_exec_runtime
= 0;
1657 p
->se
.prev_sum_exec_runtime
= 0;
1659 #ifdef CONFIG_SCHEDSTATS
1660 p
->se
.wait_start
= 0;
1661 p
->se
.sum_sleep_runtime
= 0;
1662 p
->se
.sleep_start
= 0;
1663 p
->se
.block_start
= 0;
1664 p
->se
.sleep_max
= 0;
1665 p
->se
.block_max
= 0;
1667 p
->se
.slice_max
= 0;
1671 INIT_LIST_HEAD(&p
->run_list
);
1674 #ifdef CONFIG_PREEMPT_NOTIFIERS
1675 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1679 * We mark the process as running here, but have not actually
1680 * inserted it onto the runqueue yet. This guarantees that
1681 * nobody will actually run it, and a signal or other external
1682 * event cannot wake it up and insert it on the runqueue either.
1684 p
->state
= TASK_RUNNING
;
1688 * fork()/clone()-time setup:
1690 void sched_fork(struct task_struct
*p
, int clone_flags
)
1692 int cpu
= get_cpu();
1697 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1699 set_task_cpu(p
, cpu
);
1702 * Make sure we do not leak PI boosting priority to the child:
1704 p
->prio
= current
->normal_prio
;
1705 if (!rt_prio(p
->prio
))
1706 p
->sched_class
= &fair_sched_class
;
1708 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1709 if (likely(sched_info_on()))
1710 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1712 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1715 #ifdef CONFIG_PREEMPT
1716 /* Want to start with kernel preemption disabled. */
1717 task_thread_info(p
)->preempt_count
= 1;
1723 * wake_up_new_task - wake up a newly created task for the first time.
1725 * This function will do some initial scheduler statistics housekeeping
1726 * that must be done for every newly created context, then puts the task
1727 * on the runqueue and wakes it.
1729 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1731 unsigned long flags
;
1734 rq
= task_rq_lock(p
, &flags
);
1735 BUG_ON(p
->state
!= TASK_RUNNING
);
1736 update_rq_clock(rq
);
1738 p
->prio
= effective_prio(p
);
1740 if (!p
->sched_class
->task_new
|| !current
->se
.on_rq
) {
1741 activate_task(rq
, p
, 0);
1744 * Let the scheduling class do new task startup
1745 * management (if any):
1747 p
->sched_class
->task_new(rq
, p
);
1748 inc_nr_running(p
, rq
);
1750 check_preempt_curr(rq
, p
);
1751 task_rq_unlock(rq
, &flags
);
1754 #ifdef CONFIG_PREEMPT_NOTIFIERS
1757 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
1758 * @notifier: notifier struct to register
1760 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1762 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1764 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1767 * preempt_notifier_unregister - no longer interested in preemption notifications
1768 * @notifier: notifier struct to unregister
1770 * This is safe to call from within a preemption notifier.
1772 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1774 hlist_del(¬ifier
->link
);
1776 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1778 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1780 struct preempt_notifier
*notifier
;
1781 struct hlist_node
*node
;
1783 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1784 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1788 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1789 struct task_struct
*next
)
1791 struct preempt_notifier
*notifier
;
1792 struct hlist_node
*node
;
1794 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1795 notifier
->ops
->sched_out(notifier
, next
);
1800 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1805 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1806 struct task_struct
*next
)
1813 * prepare_task_switch - prepare to switch tasks
1814 * @rq: the runqueue preparing to switch
1815 * @prev: the current task that is being switched out
1816 * @next: the task we are going to switch to.
1818 * This is called with the rq lock held and interrupts off. It must
1819 * be paired with a subsequent finish_task_switch after the context
1822 * prepare_task_switch sets up locking and calls architecture specific
1826 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1827 struct task_struct
*next
)
1829 fire_sched_out_preempt_notifiers(prev
, next
);
1830 prepare_lock_switch(rq
, next
);
1831 prepare_arch_switch(next
);
1835 * finish_task_switch - clean up after a task-switch
1836 * @rq: runqueue associated with task-switch
1837 * @prev: the thread we just switched away from.
1839 * finish_task_switch must be called after the context switch, paired
1840 * with a prepare_task_switch call before the context switch.
1841 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1842 * and do any other architecture-specific cleanup actions.
1844 * Note that we may have delayed dropping an mm in context_switch(). If
1845 * so, we finish that here outside of the runqueue lock. (Doing it
1846 * with the lock held can cause deadlocks; see schedule() for
1849 static void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1850 __releases(rq
->lock
)
1852 struct mm_struct
*mm
= rq
->prev_mm
;
1858 * A task struct has one reference for the use as "current".
1859 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1860 * schedule one last time. The schedule call will never return, and
1861 * the scheduled task must drop that reference.
1862 * The test for TASK_DEAD must occur while the runqueue locks are
1863 * still held, otherwise prev could be scheduled on another cpu, die
1864 * there before we look at prev->state, and then the reference would
1866 * Manfred Spraul <manfred@colorfullife.com>
1868 prev_state
= prev
->state
;
1869 finish_arch_switch(prev
);
1870 finish_lock_switch(rq
, prev
);
1871 fire_sched_in_preempt_notifiers(current
);
1874 if (unlikely(prev_state
== TASK_DEAD
)) {
1876 * Remove function-return probe instances associated with this
1877 * task and put them back on the free list.
1879 kprobe_flush_task(prev
);
1880 put_task_struct(prev
);
1885 * schedule_tail - first thing a freshly forked thread must call.
1886 * @prev: the thread we just switched away from.
1888 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1889 __releases(rq
->lock
)
1891 struct rq
*rq
= this_rq();
1893 finish_task_switch(rq
, prev
);
1894 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1895 /* In this case, finish_task_switch does not reenable preemption */
1898 if (current
->set_child_tid
)
1899 put_user(task_pid_vnr(current
), current
->set_child_tid
);
1903 * context_switch - switch to the new MM and the new
1904 * thread's register state.
1907 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1908 struct task_struct
*next
)
1910 struct mm_struct
*mm
, *oldmm
;
1912 prepare_task_switch(rq
, prev
, next
);
1914 oldmm
= prev
->active_mm
;
1916 * For paravirt, this is coupled with an exit in switch_to to
1917 * combine the page table reload and the switch backend into
1920 arch_enter_lazy_cpu_mode();
1922 if (unlikely(!mm
)) {
1923 next
->active_mm
= oldmm
;
1924 atomic_inc(&oldmm
->mm_count
);
1925 enter_lazy_tlb(oldmm
, next
);
1927 switch_mm(oldmm
, mm
, next
);
1929 if (unlikely(!prev
->mm
)) {
1930 prev
->active_mm
= NULL
;
1931 rq
->prev_mm
= oldmm
;
1934 * Since the runqueue lock will be released by the next
1935 * task (which is an invalid locking op but in the case
1936 * of the scheduler it's an obvious special-case), so we
1937 * do an early lockdep release here:
1939 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1940 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1943 /* Here we just switch the register state and the stack. */
1944 switch_to(prev
, next
, prev
);
1948 * this_rq must be evaluated again because prev may have moved
1949 * CPUs since it called schedule(), thus the 'rq' on its stack
1950 * frame will be invalid.
1952 finish_task_switch(this_rq(), prev
);
1956 * nr_running, nr_uninterruptible and nr_context_switches:
1958 * externally visible scheduler statistics: current number of runnable
1959 * threads, current number of uninterruptible-sleeping threads, total
1960 * number of context switches performed since bootup.
1962 unsigned long nr_running(void)
1964 unsigned long i
, sum
= 0;
1966 for_each_online_cpu(i
)
1967 sum
+= cpu_rq(i
)->nr_running
;
1972 unsigned long nr_uninterruptible(void)
1974 unsigned long i
, sum
= 0;
1976 for_each_possible_cpu(i
)
1977 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1980 * Since we read the counters lockless, it might be slightly
1981 * inaccurate. Do not allow it to go below zero though:
1983 if (unlikely((long)sum
< 0))
1989 unsigned long long nr_context_switches(void)
1992 unsigned long long sum
= 0;
1994 for_each_possible_cpu(i
)
1995 sum
+= cpu_rq(i
)->nr_switches
;
2000 unsigned long nr_iowait(void)
2002 unsigned long i
, sum
= 0;
2004 for_each_possible_cpu(i
)
2005 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
2010 unsigned long nr_active(void)
2012 unsigned long i
, running
= 0, uninterruptible
= 0;
2014 for_each_online_cpu(i
) {
2015 running
+= cpu_rq(i
)->nr_running
;
2016 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
2019 if (unlikely((long)uninterruptible
< 0))
2020 uninterruptible
= 0;
2022 return running
+ uninterruptible
;
2026 * Update rq->cpu_load[] statistics. This function is usually called every
2027 * scheduler tick (TICK_NSEC).
2029 static void update_cpu_load(struct rq
*this_rq
)
2031 unsigned long this_load
= this_rq
->load
.weight
;
2034 this_rq
->nr_load_updates
++;
2036 /* Update our load: */
2037 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
2038 unsigned long old_load
, new_load
;
2040 /* scale is effectively 1 << i now, and >> i divides by scale */
2042 old_load
= this_rq
->cpu_load
[i
];
2043 new_load
= this_load
;
2045 * Round up the averaging division if load is increasing. This
2046 * prevents us from getting stuck on 9 if the load is 10, for
2049 if (new_load
> old_load
)
2050 new_load
+= scale
-1;
2051 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2058 * double_rq_lock - safely lock two runqueues
2060 * Note this does not disable interrupts like task_rq_lock,
2061 * you need to do so manually before calling.
2063 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
2064 __acquires(rq1
->lock
)
2065 __acquires(rq2
->lock
)
2067 BUG_ON(!irqs_disabled());
2069 spin_lock(&rq1
->lock
);
2070 __acquire(rq2
->lock
); /* Fake it out ;) */
2073 spin_lock(&rq1
->lock
);
2074 spin_lock(&rq2
->lock
);
2076 spin_lock(&rq2
->lock
);
2077 spin_lock(&rq1
->lock
);
2080 update_rq_clock(rq1
);
2081 update_rq_clock(rq2
);
2085 * double_rq_unlock - safely unlock two runqueues
2087 * Note this does not restore interrupts like task_rq_unlock,
2088 * you need to do so manually after calling.
2090 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2091 __releases(rq1
->lock
)
2092 __releases(rq2
->lock
)
2094 spin_unlock(&rq1
->lock
);
2096 spin_unlock(&rq2
->lock
);
2098 __release(rq2
->lock
);
2102 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2104 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2105 __releases(this_rq
->lock
)
2106 __acquires(busiest
->lock
)
2107 __acquires(this_rq
->lock
)
2109 if (unlikely(!irqs_disabled())) {
2110 /* printk() doesn't work good under rq->lock */
2111 spin_unlock(&this_rq
->lock
);
2114 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2115 if (busiest
< this_rq
) {
2116 spin_unlock(&this_rq
->lock
);
2117 spin_lock(&busiest
->lock
);
2118 spin_lock(&this_rq
->lock
);
2120 spin_lock(&busiest
->lock
);
2125 * If dest_cpu is allowed for this process, migrate the task to it.
2126 * This is accomplished by forcing the cpu_allowed mask to only
2127 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2128 * the cpu_allowed mask is restored.
2130 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2132 struct migration_req req
;
2133 unsigned long flags
;
2136 rq
= task_rq_lock(p
, &flags
);
2137 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2138 || unlikely(cpu_is_offline(dest_cpu
)))
2141 /* force the process onto the specified CPU */
2142 if (migrate_task(p
, dest_cpu
, &req
)) {
2143 /* Need to wait for migration thread (might exit: take ref). */
2144 struct task_struct
*mt
= rq
->migration_thread
;
2146 get_task_struct(mt
);
2147 task_rq_unlock(rq
, &flags
);
2148 wake_up_process(mt
);
2149 put_task_struct(mt
);
2150 wait_for_completion(&req
.done
);
2155 task_rq_unlock(rq
, &flags
);
2159 * sched_exec - execve() is a valuable balancing opportunity, because at
2160 * this point the task has the smallest effective memory and cache footprint.
2162 void sched_exec(void)
2164 int new_cpu
, this_cpu
= get_cpu();
2165 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2167 if (new_cpu
!= this_cpu
)
2168 sched_migrate_task(current
, new_cpu
);
2172 * pull_task - move a task from a remote runqueue to the local runqueue.
2173 * Both runqueues must be locked.
2175 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2176 struct rq
*this_rq
, int this_cpu
)
2178 deactivate_task(src_rq
, p
, 0);
2179 set_task_cpu(p
, this_cpu
);
2180 activate_task(this_rq
, p
, 0);
2182 * Note that idle threads have a prio of MAX_PRIO, for this test
2183 * to be always true for them.
2185 check_preempt_curr(this_rq
, p
);
2189 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2192 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2193 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2197 * We do not migrate tasks that are:
2198 * 1) running (obviously), or
2199 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2200 * 3) are cache-hot on their current CPU.
2202 if (!cpu_isset(this_cpu
, p
->cpus_allowed
)) {
2203 schedstat_inc(p
, se
.nr_failed_migrations_affine
);
2208 if (task_running(rq
, p
)) {
2209 schedstat_inc(p
, se
.nr_failed_migrations_running
);
2214 * Aggressive migration if:
2215 * 1) task is cache cold, or
2216 * 2) too many balance attempts have failed.
2219 if (!task_hot(p
, rq
->clock
, sd
) ||
2220 sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2221 #ifdef CONFIG_SCHEDSTATS
2222 if (task_hot(p
, rq
->clock
, sd
)) {
2223 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2224 schedstat_inc(p
, se
.nr_forced_migrations
);
2230 if (task_hot(p
, rq
->clock
, sd
)) {
2231 schedstat_inc(p
, se
.nr_failed_migrations_hot
);
2237 static unsigned long
2238 balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2239 unsigned long max_load_move
, struct sched_domain
*sd
,
2240 enum cpu_idle_type idle
, int *all_pinned
,
2241 int *this_best_prio
, struct rq_iterator
*iterator
)
2243 int loops
= 0, pulled
= 0, pinned
= 0, skip_for_load
;
2244 struct task_struct
*p
;
2245 long rem_load_move
= max_load_move
;
2247 if (max_load_move
== 0)
2253 * Start the load-balancing iterator:
2255 p
= iterator
->start(iterator
->arg
);
2257 if (!p
|| loops
++ > sysctl_sched_nr_migrate
)
2260 * To help distribute high priority tasks across CPUs we don't
2261 * skip a task if it will be the highest priority task (i.e. smallest
2262 * prio value) on its new queue regardless of its load weight
2264 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2265 SCHED_LOAD_SCALE_FUZZ
;
2266 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2267 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2268 p
= iterator
->next(iterator
->arg
);
2272 pull_task(busiest
, p
, this_rq
, this_cpu
);
2274 rem_load_move
-= p
->se
.load
.weight
;
2277 * We only want to steal up to the prescribed amount of weighted load.
2279 if (rem_load_move
> 0) {
2280 if (p
->prio
< *this_best_prio
)
2281 *this_best_prio
= p
->prio
;
2282 p
= iterator
->next(iterator
->arg
);
2287 * Right now, this is one of only two places pull_task() is called,
2288 * so we can safely collect pull_task() stats here rather than
2289 * inside pull_task().
2291 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2294 *all_pinned
= pinned
;
2296 return max_load_move
- rem_load_move
;
2300 * move_tasks tries to move up to max_load_move weighted load from busiest to
2301 * this_rq, as part of a balancing operation within domain "sd".
2302 * Returns 1 if successful and 0 otherwise.
2304 * Called with both runqueues locked.
2306 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2307 unsigned long max_load_move
,
2308 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2311 const struct sched_class
*class = sched_class_highest
;
2312 unsigned long total_load_moved
= 0;
2313 int this_best_prio
= this_rq
->curr
->prio
;
2317 class->load_balance(this_rq
, this_cpu
, busiest
,
2318 max_load_move
- total_load_moved
,
2319 sd
, idle
, all_pinned
, &this_best_prio
);
2320 class = class->next
;
2321 } while (class && max_load_move
> total_load_moved
);
2323 return total_load_moved
> 0;
2327 iter_move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2328 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2329 struct rq_iterator
*iterator
)
2331 struct task_struct
*p
= iterator
->start(iterator
->arg
);
2335 if (can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2336 pull_task(busiest
, p
, this_rq
, this_cpu
);
2338 * Right now, this is only the second place pull_task()
2339 * is called, so we can safely collect pull_task()
2340 * stats here rather than inside pull_task().
2342 schedstat_inc(sd
, lb_gained
[idle
]);
2346 p
= iterator
->next(iterator
->arg
);
2353 * move_one_task tries to move exactly one task from busiest to this_rq, as
2354 * part of active balancing operations within "domain".
2355 * Returns 1 if successful and 0 otherwise.
2357 * Called with both runqueues locked.
2359 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2360 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2362 const struct sched_class
*class;
2364 for (class = sched_class_highest
; class; class = class->next
)
2365 if (class->move_one_task(this_rq
, this_cpu
, busiest
, sd
, idle
))
2372 * find_busiest_group finds and returns the busiest CPU group within the
2373 * domain. It calculates and returns the amount of weighted load which
2374 * should be moved to restore balance via the imbalance parameter.
2376 static struct sched_group
*
2377 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2378 unsigned long *imbalance
, enum cpu_idle_type idle
,
2379 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2381 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2382 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2383 unsigned long max_pull
;
2384 unsigned long busiest_load_per_task
, busiest_nr_running
;
2385 unsigned long this_load_per_task
, this_nr_running
;
2386 int load_idx
, group_imb
= 0;
2387 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2388 int power_savings_balance
= 1;
2389 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2390 unsigned long min_nr_running
= ULONG_MAX
;
2391 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2394 max_load
= this_load
= total_load
= total_pwr
= 0;
2395 busiest_load_per_task
= busiest_nr_running
= 0;
2396 this_load_per_task
= this_nr_running
= 0;
2397 if (idle
== CPU_NOT_IDLE
)
2398 load_idx
= sd
->busy_idx
;
2399 else if (idle
== CPU_NEWLY_IDLE
)
2400 load_idx
= sd
->newidle_idx
;
2402 load_idx
= sd
->idle_idx
;
2405 unsigned long load
, group_capacity
, max_cpu_load
, min_cpu_load
;
2408 int __group_imb
= 0;
2409 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2410 unsigned long sum_nr_running
, sum_weighted_load
;
2412 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2415 balance_cpu
= first_cpu(group
->cpumask
);
2417 /* Tally up the load of all CPUs in the group */
2418 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2420 min_cpu_load
= ~0UL;
2422 for_each_cpu_mask(i
, group
->cpumask
) {
2425 if (!cpu_isset(i
, *cpus
))
2430 if (*sd_idle
&& rq
->nr_running
)
2433 /* Bias balancing toward cpus of our domain */
2435 if (idle_cpu(i
) && !first_idle_cpu
) {
2440 load
= target_load(i
, load_idx
);
2442 load
= source_load(i
, load_idx
);
2443 if (load
> max_cpu_load
)
2444 max_cpu_load
= load
;
2445 if (min_cpu_load
> load
)
2446 min_cpu_load
= load
;
2450 sum_nr_running
+= rq
->nr_running
;
2451 sum_weighted_load
+= weighted_cpuload(i
);
2455 * First idle cpu or the first cpu(busiest) in this sched group
2456 * is eligible for doing load balancing at this and above
2457 * domains. In the newly idle case, we will allow all the cpu's
2458 * to do the newly idle load balance.
2460 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2461 balance_cpu
!= this_cpu
&& balance
) {
2466 total_load
+= avg_load
;
2467 total_pwr
+= group
->__cpu_power
;
2469 /* Adjust by relative CPU power of the group */
2470 avg_load
= sg_div_cpu_power(group
,
2471 avg_load
* SCHED_LOAD_SCALE
);
2473 if ((max_cpu_load
- min_cpu_load
) > SCHED_LOAD_SCALE
)
2476 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2479 this_load
= avg_load
;
2481 this_nr_running
= sum_nr_running
;
2482 this_load_per_task
= sum_weighted_load
;
2483 } else if (avg_load
> max_load
&&
2484 (sum_nr_running
> group_capacity
|| __group_imb
)) {
2485 max_load
= avg_load
;
2487 busiest_nr_running
= sum_nr_running
;
2488 busiest_load_per_task
= sum_weighted_load
;
2489 group_imb
= __group_imb
;
2492 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2494 * Busy processors will not participate in power savings
2497 if (idle
== CPU_NOT_IDLE
||
2498 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2502 * If the local group is idle or completely loaded
2503 * no need to do power savings balance at this domain
2505 if (local_group
&& (this_nr_running
>= group_capacity
||
2507 power_savings_balance
= 0;
2510 * If a group is already running at full capacity or idle,
2511 * don't include that group in power savings calculations
2513 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2518 * Calculate the group which has the least non-idle load.
2519 * This is the group from where we need to pick up the load
2522 if ((sum_nr_running
< min_nr_running
) ||
2523 (sum_nr_running
== min_nr_running
&&
2524 first_cpu(group
->cpumask
) <
2525 first_cpu(group_min
->cpumask
))) {
2527 min_nr_running
= sum_nr_running
;
2528 min_load_per_task
= sum_weighted_load
/
2533 * Calculate the group which is almost near its
2534 * capacity but still has some space to pick up some load
2535 * from other group and save more power
2537 if (sum_nr_running
<= group_capacity
- 1) {
2538 if (sum_nr_running
> leader_nr_running
||
2539 (sum_nr_running
== leader_nr_running
&&
2540 first_cpu(group
->cpumask
) >
2541 first_cpu(group_leader
->cpumask
))) {
2542 group_leader
= group
;
2543 leader_nr_running
= sum_nr_running
;
2548 group
= group
->next
;
2549 } while (group
!= sd
->groups
);
2551 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2554 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2556 if (this_load
>= avg_load
||
2557 100*max_load
<= sd
->imbalance_pct
*this_load
)
2560 busiest_load_per_task
/= busiest_nr_running
;
2562 busiest_load_per_task
= min(busiest_load_per_task
, avg_load
);
2565 * We're trying to get all the cpus to the average_load, so we don't
2566 * want to push ourselves above the average load, nor do we wish to
2567 * reduce the max loaded cpu below the average load, as either of these
2568 * actions would just result in more rebalancing later, and ping-pong
2569 * tasks around. Thus we look for the minimum possible imbalance.
2570 * Negative imbalances (*we* are more loaded than anyone else) will
2571 * be counted as no imbalance for these purposes -- we can't fix that
2572 * by pulling tasks to us. Be careful of negative numbers as they'll
2573 * appear as very large values with unsigned longs.
2575 if (max_load
<= busiest_load_per_task
)
2579 * In the presence of smp nice balancing, certain scenarios can have
2580 * max load less than avg load(as we skip the groups at or below
2581 * its cpu_power, while calculating max_load..)
2583 if (max_load
< avg_load
) {
2585 goto small_imbalance
;
2588 /* Don't want to pull so many tasks that a group would go idle */
2589 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2591 /* How much load to actually move to equalise the imbalance */
2592 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2593 (avg_load
- this_load
) * this->__cpu_power
)
2597 * if *imbalance is less than the average load per runnable task
2598 * there is no gaurantee that any tasks will be moved so we'll have
2599 * a think about bumping its value to force at least one task to be
2602 if (*imbalance
< busiest_load_per_task
) {
2603 unsigned long tmp
, pwr_now
, pwr_move
;
2607 pwr_move
= pwr_now
= 0;
2609 if (this_nr_running
) {
2610 this_load_per_task
/= this_nr_running
;
2611 if (busiest_load_per_task
> this_load_per_task
)
2614 this_load_per_task
= SCHED_LOAD_SCALE
;
2616 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
2617 busiest_load_per_task
* imbn
) {
2618 *imbalance
= busiest_load_per_task
;
2623 * OK, we don't have enough imbalance to justify moving tasks,
2624 * however we may be able to increase total CPU power used by
2628 pwr_now
+= busiest
->__cpu_power
*
2629 min(busiest_load_per_task
, max_load
);
2630 pwr_now
+= this->__cpu_power
*
2631 min(this_load_per_task
, this_load
);
2632 pwr_now
/= SCHED_LOAD_SCALE
;
2634 /* Amount of load we'd subtract */
2635 tmp
= sg_div_cpu_power(busiest
,
2636 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2638 pwr_move
+= busiest
->__cpu_power
*
2639 min(busiest_load_per_task
, max_load
- tmp
);
2641 /* Amount of load we'd add */
2642 if (max_load
* busiest
->__cpu_power
<
2643 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2644 tmp
= sg_div_cpu_power(this,
2645 max_load
* busiest
->__cpu_power
);
2647 tmp
= sg_div_cpu_power(this,
2648 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2649 pwr_move
+= this->__cpu_power
*
2650 min(this_load_per_task
, this_load
+ tmp
);
2651 pwr_move
/= SCHED_LOAD_SCALE
;
2653 /* Move if we gain throughput */
2654 if (pwr_move
> pwr_now
)
2655 *imbalance
= busiest_load_per_task
;
2661 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2662 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2665 if (this == group_leader
&& group_leader
!= group_min
) {
2666 *imbalance
= min_load_per_task
;
2676 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2679 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
2680 unsigned long imbalance
, cpumask_t
*cpus
)
2682 struct rq
*busiest
= NULL
, *rq
;
2683 unsigned long max_load
= 0;
2686 for_each_cpu_mask(i
, group
->cpumask
) {
2689 if (!cpu_isset(i
, *cpus
))
2693 wl
= weighted_cpuload(i
);
2695 if (rq
->nr_running
== 1 && wl
> imbalance
)
2698 if (wl
> max_load
) {
2708 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2709 * so long as it is large enough.
2711 #define MAX_PINNED_INTERVAL 512
2714 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2715 * tasks if there is an imbalance.
2717 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2718 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2721 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2722 struct sched_group
*group
;
2723 unsigned long imbalance
;
2725 cpumask_t cpus
= CPU_MASK_ALL
;
2726 unsigned long flags
;
2729 * When power savings policy is enabled for the parent domain, idle
2730 * sibling can pick up load irrespective of busy siblings. In this case,
2731 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2732 * portraying it as CPU_NOT_IDLE.
2734 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2735 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2738 schedstat_inc(sd
, lb_count
[idle
]);
2741 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2748 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2752 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2754 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2758 BUG_ON(busiest
== this_rq
);
2760 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2763 if (busiest
->nr_running
> 1) {
2765 * Attempt to move tasks. If find_busiest_group has found
2766 * an imbalance but busiest->nr_running <= 1, the group is
2767 * still unbalanced. ld_moved simply stays zero, so it is
2768 * correctly treated as an imbalance.
2770 local_irq_save(flags
);
2771 double_rq_lock(this_rq
, busiest
);
2772 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2773 imbalance
, sd
, idle
, &all_pinned
);
2774 double_rq_unlock(this_rq
, busiest
);
2775 local_irq_restore(flags
);
2778 * some other cpu did the load balance for us.
2780 if (ld_moved
&& this_cpu
!= smp_processor_id())
2781 resched_cpu(this_cpu
);
2783 /* All tasks on this runqueue were pinned by CPU affinity */
2784 if (unlikely(all_pinned
)) {
2785 cpu_clear(cpu_of(busiest
), cpus
);
2786 if (!cpus_empty(cpus
))
2793 schedstat_inc(sd
, lb_failed
[idle
]);
2794 sd
->nr_balance_failed
++;
2796 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2798 spin_lock_irqsave(&busiest
->lock
, flags
);
2800 /* don't kick the migration_thread, if the curr
2801 * task on busiest cpu can't be moved to this_cpu
2803 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2804 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2806 goto out_one_pinned
;
2809 if (!busiest
->active_balance
) {
2810 busiest
->active_balance
= 1;
2811 busiest
->push_cpu
= this_cpu
;
2814 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2816 wake_up_process(busiest
->migration_thread
);
2819 * We've kicked active balancing, reset the failure
2822 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2825 sd
->nr_balance_failed
= 0;
2827 if (likely(!active_balance
)) {
2828 /* We were unbalanced, so reset the balancing interval */
2829 sd
->balance_interval
= sd
->min_interval
;
2832 * If we've begun active balancing, start to back off. This
2833 * case may not be covered by the all_pinned logic if there
2834 * is only 1 task on the busy runqueue (because we don't call
2837 if (sd
->balance_interval
< sd
->max_interval
)
2838 sd
->balance_interval
*= 2;
2841 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2842 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2847 schedstat_inc(sd
, lb_balanced
[idle
]);
2849 sd
->nr_balance_failed
= 0;
2852 /* tune up the balancing interval */
2853 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2854 (sd
->balance_interval
< sd
->max_interval
))
2855 sd
->balance_interval
*= 2;
2857 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2858 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2864 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2865 * tasks if there is an imbalance.
2867 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2868 * this_rq is locked.
2871 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2873 struct sched_group
*group
;
2874 struct rq
*busiest
= NULL
;
2875 unsigned long imbalance
;
2879 cpumask_t cpus
= CPU_MASK_ALL
;
2882 * When power savings policy is enabled for the parent domain, idle
2883 * sibling can pick up load irrespective of busy siblings. In this case,
2884 * let the state of idle sibling percolate up as IDLE, instead of
2885 * portraying it as CPU_NOT_IDLE.
2887 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2888 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2891 schedstat_inc(sd
, lb_count
[CPU_NEWLY_IDLE
]);
2893 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
2894 &sd_idle
, &cpus
, NULL
);
2896 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
2900 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
2903 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
2907 BUG_ON(busiest
== this_rq
);
2909 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
2912 if (busiest
->nr_running
> 1) {
2913 /* Attempt to move tasks */
2914 double_lock_balance(this_rq
, busiest
);
2915 /* this_rq->clock is already updated */
2916 update_rq_clock(busiest
);
2917 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2918 imbalance
, sd
, CPU_NEWLY_IDLE
,
2920 spin_unlock(&busiest
->lock
);
2922 if (unlikely(all_pinned
)) {
2923 cpu_clear(cpu_of(busiest
), cpus
);
2924 if (!cpus_empty(cpus
))
2930 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
2931 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2932 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2935 sd
->nr_balance_failed
= 0;
2940 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
2941 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2942 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2944 sd
->nr_balance_failed
= 0;
2950 * idle_balance is called by schedule() if this_cpu is about to become
2951 * idle. Attempts to pull tasks from other CPUs.
2953 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2955 struct sched_domain
*sd
;
2956 int pulled_task
= -1;
2957 unsigned long next_balance
= jiffies
+ HZ
;
2959 for_each_domain(this_cpu
, sd
) {
2960 unsigned long interval
;
2962 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2965 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
2966 /* If we've pulled tasks over stop searching: */
2967 pulled_task
= load_balance_newidle(this_cpu
,
2970 interval
= msecs_to_jiffies(sd
->balance_interval
);
2971 if (time_after(next_balance
, sd
->last_balance
+ interval
))
2972 next_balance
= sd
->last_balance
+ interval
;
2976 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
2978 * We are going idle. next_balance may be set based on
2979 * a busy processor. So reset next_balance.
2981 this_rq
->next_balance
= next_balance
;
2986 * active_load_balance is run by migration threads. It pushes running tasks
2987 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2988 * running on each physical CPU where possible, and avoids physical /
2989 * logical imbalances.
2991 * Called with busiest_rq locked.
2993 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
2995 int target_cpu
= busiest_rq
->push_cpu
;
2996 struct sched_domain
*sd
;
2997 struct rq
*target_rq
;
2999 /* Is there any task to move? */
3000 if (busiest_rq
->nr_running
<= 1)
3003 target_rq
= cpu_rq(target_cpu
);
3006 * This condition is "impossible", if it occurs
3007 * we need to fix it. Originally reported by
3008 * Bjorn Helgaas on a 128-cpu setup.
3010 BUG_ON(busiest_rq
== target_rq
);
3012 /* move a task from busiest_rq to target_rq */
3013 double_lock_balance(busiest_rq
, target_rq
);
3014 update_rq_clock(busiest_rq
);
3015 update_rq_clock(target_rq
);
3017 /* Search for an sd spanning us and the target CPU. */
3018 for_each_domain(target_cpu
, sd
) {
3019 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
3020 cpu_isset(busiest_cpu
, sd
->span
))
3025 schedstat_inc(sd
, alb_count
);
3027 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
3029 schedstat_inc(sd
, alb_pushed
);
3031 schedstat_inc(sd
, alb_failed
);
3033 spin_unlock(&target_rq
->lock
);
3038 atomic_t load_balancer
;
3040 } nohz ____cacheline_aligned
= {
3041 .load_balancer
= ATOMIC_INIT(-1),
3042 .cpu_mask
= CPU_MASK_NONE
,
3046 * This routine will try to nominate the ilb (idle load balancing)
3047 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
3048 * load balancing on behalf of all those cpus. If all the cpus in the system
3049 * go into this tickless mode, then there will be no ilb owner (as there is
3050 * no need for one) and all the cpus will sleep till the next wakeup event
3053 * For the ilb owner, tick is not stopped. And this tick will be used
3054 * for idle load balancing. ilb owner will still be part of
3057 * While stopping the tick, this cpu will become the ilb owner if there
3058 * is no other owner. And will be the owner till that cpu becomes busy
3059 * or if all cpus in the system stop their ticks at which point
3060 * there is no need for ilb owner.
3062 * When the ilb owner becomes busy, it nominates another owner, during the
3063 * next busy scheduler_tick()
3065 int select_nohz_load_balancer(int stop_tick
)
3067 int cpu
= smp_processor_id();
3070 cpu_set(cpu
, nohz
.cpu_mask
);
3071 cpu_rq(cpu
)->in_nohz_recently
= 1;
3074 * If we are going offline and still the leader, give up!
3076 if (cpu_is_offline(cpu
) &&
3077 atomic_read(&nohz
.load_balancer
) == cpu
) {
3078 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3083 /* time for ilb owner also to sleep */
3084 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3085 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3086 atomic_set(&nohz
.load_balancer
, -1);
3090 if (atomic_read(&nohz
.load_balancer
) == -1) {
3091 /* make me the ilb owner */
3092 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
3094 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
3097 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
3100 cpu_clear(cpu
, nohz
.cpu_mask
);
3102 if (atomic_read(&nohz
.load_balancer
) == cpu
)
3103 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
3110 static DEFINE_SPINLOCK(balancing
);
3113 * It checks each scheduling domain to see if it is due to be balanced,
3114 * and initiates a balancing operation if so.
3116 * Balancing parameters are set up in arch_init_sched_domains.
3118 static void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3121 struct rq
*rq
= cpu_rq(cpu
);
3122 unsigned long interval
;
3123 struct sched_domain
*sd
;
3124 /* Earliest time when we have to do rebalance again */
3125 unsigned long next_balance
= jiffies
+ 60*HZ
;
3126 int update_next_balance
= 0;
3128 for_each_domain(cpu
, sd
) {
3129 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3132 interval
= sd
->balance_interval
;
3133 if (idle
!= CPU_IDLE
)
3134 interval
*= sd
->busy_factor
;
3136 /* scale ms to jiffies */
3137 interval
= msecs_to_jiffies(interval
);
3138 if (unlikely(!interval
))
3140 if (interval
> HZ
*NR_CPUS
/10)
3141 interval
= HZ
*NR_CPUS
/10;
3144 if (sd
->flags
& SD_SERIALIZE
) {
3145 if (!spin_trylock(&balancing
))
3149 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3150 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3152 * We've pulled tasks over so either we're no
3153 * longer idle, or one of our SMT siblings is
3156 idle
= CPU_NOT_IDLE
;
3158 sd
->last_balance
= jiffies
;
3160 if (sd
->flags
& SD_SERIALIZE
)
3161 spin_unlock(&balancing
);
3163 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3164 next_balance
= sd
->last_balance
+ interval
;
3165 update_next_balance
= 1;
3169 * Stop the load balance at this level. There is another
3170 * CPU in our sched group which is doing load balancing more
3178 * next_balance will be updated only when there is a need.
3179 * When the cpu is attached to null domain for ex, it will not be
3182 if (likely(update_next_balance
))
3183 rq
->next_balance
= next_balance
;
3187 * run_rebalance_domains is triggered when needed from the scheduler tick.
3188 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3189 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3191 static void run_rebalance_domains(struct softirq_action
*h
)
3193 int this_cpu
= smp_processor_id();
3194 struct rq
*this_rq
= cpu_rq(this_cpu
);
3195 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3196 CPU_IDLE
: CPU_NOT_IDLE
;
3198 rebalance_domains(this_cpu
, idle
);
3202 * If this cpu is the owner for idle load balancing, then do the
3203 * balancing on behalf of the other idle cpus whose ticks are
3206 if (this_rq
->idle_at_tick
&&
3207 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3208 cpumask_t cpus
= nohz
.cpu_mask
;
3212 cpu_clear(this_cpu
, cpus
);
3213 for_each_cpu_mask(balance_cpu
, cpus
) {
3215 * If this cpu gets work to do, stop the load balancing
3216 * work being done for other cpus. Next load
3217 * balancing owner will pick it up.
3222 rebalance_domains(balance_cpu
, CPU_IDLE
);
3224 rq
= cpu_rq(balance_cpu
);
3225 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3226 this_rq
->next_balance
= rq
->next_balance
;
3233 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3235 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3236 * idle load balancing owner or decide to stop the periodic load balancing,
3237 * if the whole system is idle.
3239 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3243 * If we were in the nohz mode recently and busy at the current
3244 * scheduler tick, then check if we need to nominate new idle
3247 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3248 rq
->in_nohz_recently
= 0;
3250 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3251 cpu_clear(cpu
, nohz
.cpu_mask
);
3252 atomic_set(&nohz
.load_balancer
, -1);
3255 if (atomic_read(&nohz
.load_balancer
) == -1) {
3257 * simple selection for now: Nominate the
3258 * first cpu in the nohz list to be the next
3261 * TBD: Traverse the sched domains and nominate
3262 * the nearest cpu in the nohz.cpu_mask.
3264 int ilb
= first_cpu(nohz
.cpu_mask
);
3272 * If this cpu is idle and doing idle load balancing for all the
3273 * cpus with ticks stopped, is it time for that to stop?
3275 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3276 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3282 * If this cpu is idle and the idle load balancing is done by
3283 * someone else, then no need raise the SCHED_SOFTIRQ
3285 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3286 cpu_isset(cpu
, nohz
.cpu_mask
))
3289 if (time_after_eq(jiffies
, rq
->next_balance
))
3290 raise_softirq(SCHED_SOFTIRQ
);
3293 #else /* CONFIG_SMP */
3296 * on UP we do not need to balance between CPUs:
3298 static inline void idle_balance(int cpu
, struct rq
*rq
)
3304 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3306 EXPORT_PER_CPU_SYMBOL(kstat
);
3309 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3310 * that have not yet been banked in case the task is currently running.
3312 unsigned long long task_sched_runtime(struct task_struct
*p
)
3314 unsigned long flags
;
3318 rq
= task_rq_lock(p
, &flags
);
3319 ns
= p
->se
.sum_exec_runtime
;
3320 if (rq
->curr
== p
) {
3321 update_rq_clock(rq
);
3322 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3323 if ((s64
)delta_exec
> 0)
3326 task_rq_unlock(rq
, &flags
);
3332 * Account user cpu time to a process.
3333 * @p: the process that the cpu time gets accounted to
3334 * @cputime: the cpu time spent in user space since the last update
3336 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3338 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3341 p
->utime
= cputime_add(p
->utime
, cputime
);
3343 /* Add user time to cpustat. */
3344 tmp
= cputime_to_cputime64(cputime
);
3345 if (TASK_NICE(p
) > 0)
3346 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3348 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3352 * Account guest cpu time to a process.
3353 * @p: the process that the cpu time gets accounted to
3354 * @cputime: the cpu time spent in virtual machine since the last update
3356 static void account_guest_time(struct task_struct
*p
, cputime_t cputime
)
3359 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3361 tmp
= cputime_to_cputime64(cputime
);
3363 p
->utime
= cputime_add(p
->utime
, cputime
);
3364 p
->gtime
= cputime_add(p
->gtime
, cputime
);
3366 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3367 cpustat
->guest
= cputime64_add(cpustat
->guest
, tmp
);
3371 * Account scaled user cpu time to a process.
3372 * @p: the process that the cpu time gets accounted to
3373 * @cputime: the cpu time spent in user space since the last update
3375 void account_user_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3377 p
->utimescaled
= cputime_add(p
->utimescaled
, cputime
);
3381 * Account system cpu time to a process.
3382 * @p: the process that the cpu time gets accounted to
3383 * @hardirq_offset: the offset to subtract from hardirq_count()
3384 * @cputime: the cpu time spent in kernel space since the last update
3386 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3389 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3390 struct rq
*rq
= this_rq();
3393 if ((p
->flags
& PF_VCPU
) && (irq_count() - hardirq_offset
== 0))
3394 return account_guest_time(p
, cputime
);
3396 p
->stime
= cputime_add(p
->stime
, cputime
);
3398 /* Add system time to cpustat. */
3399 tmp
= cputime_to_cputime64(cputime
);
3400 if (hardirq_count() - hardirq_offset
)
3401 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3402 else if (softirq_count())
3403 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3404 else if (p
!= rq
->idle
)
3405 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3406 else if (atomic_read(&rq
->nr_iowait
) > 0)
3407 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3409 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3410 /* Account for system time used */
3411 acct_update_integrals(p
);
3415 * Account scaled system cpu time to a process.
3416 * @p: the process that the cpu time gets accounted to
3417 * @hardirq_offset: the offset to subtract from hardirq_count()
3418 * @cputime: the cpu time spent in kernel space since the last update
3420 void account_system_time_scaled(struct task_struct
*p
, cputime_t cputime
)
3422 p
->stimescaled
= cputime_add(p
->stimescaled
, cputime
);
3426 * Account for involuntary wait time.
3427 * @p: the process from which the cpu time has been stolen
3428 * @steal: the cpu time spent in involuntary wait
3430 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3432 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3433 cputime64_t tmp
= cputime_to_cputime64(steal
);
3434 struct rq
*rq
= this_rq();
3436 if (p
== rq
->idle
) {
3437 p
->stime
= cputime_add(p
->stime
, steal
);
3438 if (atomic_read(&rq
->nr_iowait
) > 0)
3439 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3441 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3443 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3447 * This function gets called by the timer code, with HZ frequency.
3448 * We call it with interrupts disabled.
3450 * It also gets called by the fork code, when changing the parent's
3453 void scheduler_tick(void)
3455 int cpu
= smp_processor_id();
3456 struct rq
*rq
= cpu_rq(cpu
);
3457 struct task_struct
*curr
= rq
->curr
;
3458 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3460 spin_lock(&rq
->lock
);
3461 __update_rq_clock(rq
);
3463 * Let rq->clock advance by at least TICK_NSEC:
3465 if (unlikely(rq
->clock
< next_tick
))
3466 rq
->clock
= next_tick
;
3467 rq
->tick_timestamp
= rq
->clock
;
3468 update_cpu_load(rq
);
3469 if (curr
!= rq
->idle
) /* FIXME: needed? */
3470 curr
->sched_class
->task_tick(rq
, curr
);
3471 spin_unlock(&rq
->lock
);
3474 rq
->idle_at_tick
= idle_cpu(cpu
);
3475 trigger_load_balance(rq
, cpu
);
3479 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3481 void fastcall
add_preempt_count(int val
)
3486 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3488 preempt_count() += val
;
3490 * Spinlock count overflowing soon?
3492 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3495 EXPORT_SYMBOL(add_preempt_count
);
3497 void fastcall
sub_preempt_count(int val
)
3502 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3505 * Is the spinlock portion underflowing?
3507 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3508 !(preempt_count() & PREEMPT_MASK
)))
3511 preempt_count() -= val
;
3513 EXPORT_SYMBOL(sub_preempt_count
);
3518 * Print scheduling while atomic bug:
3520 static noinline
void __schedule_bug(struct task_struct
*prev
)
3522 struct pt_regs
*regs
= get_irq_regs();
3524 printk(KERN_ERR
"BUG: scheduling while atomic: %s/%d/0x%08x\n",
3525 prev
->comm
, prev
->pid
, preempt_count());
3527 debug_show_held_locks(prev
);
3528 if (irqs_disabled())
3529 print_irqtrace_events(prev
);
3538 * Various schedule()-time debugging checks and statistics:
3540 static inline void schedule_debug(struct task_struct
*prev
)
3543 * Test if we are atomic. Since do_exit() needs to call into
3544 * schedule() atomically, we ignore that path for now.
3545 * Otherwise, whine if we are scheduling when we should not be.
3547 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3548 __schedule_bug(prev
);
3550 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3552 schedstat_inc(this_rq(), sched_count
);
3553 #ifdef CONFIG_SCHEDSTATS
3554 if (unlikely(prev
->lock_depth
>= 0)) {
3555 schedstat_inc(this_rq(), bkl_count
);
3556 schedstat_inc(prev
, sched_info
.bkl_count
);
3562 * Pick up the highest-prio task:
3564 static inline struct task_struct
*
3565 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3567 const struct sched_class
*class;
3568 struct task_struct
*p
;
3571 * Optimization: we know that if all tasks are in
3572 * the fair class we can call that function directly:
3574 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3575 p
= fair_sched_class
.pick_next_task(rq
);
3580 class = sched_class_highest
;
3582 p
= class->pick_next_task(rq
);
3586 * Will never be NULL as the idle class always
3587 * returns a non-NULL p:
3589 class = class->next
;
3594 * schedule() is the main scheduler function.
3596 asmlinkage
void __sched
schedule(void)
3598 struct task_struct
*prev
, *next
;
3605 cpu
= smp_processor_id();
3609 switch_count
= &prev
->nivcsw
;
3611 release_kernel_lock(prev
);
3612 need_resched_nonpreemptible
:
3614 schedule_debug(prev
);
3617 * Do the rq-clock update outside the rq lock:
3619 local_irq_disable();
3620 __update_rq_clock(rq
);
3621 spin_lock(&rq
->lock
);
3622 clear_tsk_need_resched(prev
);
3624 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3625 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3626 unlikely(signal_pending(prev
)))) {
3627 prev
->state
= TASK_RUNNING
;
3629 deactivate_task(rq
, prev
, 1);
3631 switch_count
= &prev
->nvcsw
;
3634 if (unlikely(!rq
->nr_running
))
3635 idle_balance(cpu
, rq
);
3637 prev
->sched_class
->put_prev_task(rq
, prev
);
3638 next
= pick_next_task(rq
, prev
);
3640 sched_info_switch(prev
, next
);
3642 if (likely(prev
!= next
)) {
3647 context_switch(rq
, prev
, next
); /* unlocks the rq */
3649 spin_unlock_irq(&rq
->lock
);
3651 if (unlikely(reacquire_kernel_lock(current
) < 0)) {
3652 cpu
= smp_processor_id();
3654 goto need_resched_nonpreemptible
;
3656 preempt_enable_no_resched();
3657 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3660 EXPORT_SYMBOL(schedule
);
3662 #ifdef CONFIG_PREEMPT
3664 * this is the entry point to schedule() from in-kernel preemption
3665 * off of preempt_enable. Kernel preemptions off return from interrupt
3666 * occur there and call schedule directly.
3668 asmlinkage
void __sched
preempt_schedule(void)
3670 struct thread_info
*ti
= current_thread_info();
3671 #ifdef CONFIG_PREEMPT_BKL
3672 struct task_struct
*task
= current
;
3673 int saved_lock_depth
;
3676 * If there is a non-zero preempt_count or interrupts are disabled,
3677 * we do not want to preempt the current task. Just return..
3679 if (likely(ti
->preempt_count
|| irqs_disabled()))
3683 add_preempt_count(PREEMPT_ACTIVE
);
3686 * We keep the big kernel semaphore locked, but we
3687 * clear ->lock_depth so that schedule() doesnt
3688 * auto-release the semaphore:
3690 #ifdef CONFIG_PREEMPT_BKL
3691 saved_lock_depth
= task
->lock_depth
;
3692 task
->lock_depth
= -1;
3695 #ifdef CONFIG_PREEMPT_BKL
3696 task
->lock_depth
= saved_lock_depth
;
3698 sub_preempt_count(PREEMPT_ACTIVE
);
3701 * Check again in case we missed a preemption opportunity
3702 * between schedule and now.
3705 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
3707 EXPORT_SYMBOL(preempt_schedule
);
3710 * this is the entry point to schedule() from kernel preemption
3711 * off of irq context.
3712 * Note, that this is called and return with irqs disabled. This will
3713 * protect us against recursive calling from irq.
3715 asmlinkage
void __sched
preempt_schedule_irq(void)
3717 struct thread_info
*ti
= current_thread_info();
3718 #ifdef CONFIG_PREEMPT_BKL
3719 struct task_struct
*task
= current
;
3720 int saved_lock_depth
;
3722 /* Catch callers which need to be fixed */
3723 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3726 add_preempt_count(PREEMPT_ACTIVE
);
3729 * We keep the big kernel semaphore locked, but we
3730 * clear ->lock_depth so that schedule() doesnt
3731 * auto-release the semaphore:
3733 #ifdef CONFIG_PREEMPT_BKL
3734 saved_lock_depth
= task
->lock_depth
;
3735 task
->lock_depth
= -1;
3739 local_irq_disable();
3740 #ifdef CONFIG_PREEMPT_BKL
3741 task
->lock_depth
= saved_lock_depth
;
3743 sub_preempt_count(PREEMPT_ACTIVE
);
3746 * Check again in case we missed a preemption opportunity
3747 * between schedule and now.
3750 } while (unlikely(test_thread_flag(TIF_NEED_RESCHED
)));
3753 #endif /* CONFIG_PREEMPT */
3755 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3758 return try_to_wake_up(curr
->private, mode
, sync
);
3760 EXPORT_SYMBOL(default_wake_function
);
3763 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3764 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3765 * number) then we wake all the non-exclusive tasks and one exclusive task.
3767 * There are circumstances in which we can try to wake a task which has already
3768 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3769 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3771 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3772 int nr_exclusive
, int sync
, void *key
)
3774 wait_queue_t
*curr
, *next
;
3776 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3777 unsigned flags
= curr
->flags
;
3779 if (curr
->func(curr
, mode
, sync
, key
) &&
3780 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3786 * __wake_up - wake up threads blocked on a waitqueue.
3788 * @mode: which threads
3789 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3790 * @key: is directly passed to the wakeup function
3792 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3793 int nr_exclusive
, void *key
)
3795 unsigned long flags
;
3797 spin_lock_irqsave(&q
->lock
, flags
);
3798 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3799 spin_unlock_irqrestore(&q
->lock
, flags
);
3801 EXPORT_SYMBOL(__wake_up
);
3804 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3806 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3808 __wake_up_common(q
, mode
, 1, 0, NULL
);
3812 * __wake_up_sync - wake up threads blocked on a waitqueue.
3814 * @mode: which threads
3815 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3817 * The sync wakeup differs that the waker knows that it will schedule
3818 * away soon, so while the target thread will be woken up, it will not
3819 * be migrated to another CPU - ie. the two threads are 'synchronized'
3820 * with each other. This can prevent needless bouncing between CPUs.
3822 * On UP it can prevent extra preemption.
3825 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3827 unsigned long flags
;
3833 if (unlikely(!nr_exclusive
))
3836 spin_lock_irqsave(&q
->lock
, flags
);
3837 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3838 spin_unlock_irqrestore(&q
->lock
, flags
);
3840 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3842 void complete(struct completion
*x
)
3844 unsigned long flags
;
3846 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3848 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3850 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3852 EXPORT_SYMBOL(complete
);
3854 void complete_all(struct completion
*x
)
3856 unsigned long flags
;
3858 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3859 x
->done
+= UINT_MAX
/2;
3860 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3862 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3864 EXPORT_SYMBOL(complete_all
);
3866 static inline long __sched
3867 do_wait_for_common(struct completion
*x
, long timeout
, int state
)
3870 DECLARE_WAITQUEUE(wait
, current
);
3872 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3873 __add_wait_queue_tail(&x
->wait
, &wait
);
3875 if (state
== TASK_INTERRUPTIBLE
&&
3876 signal_pending(current
)) {
3877 __remove_wait_queue(&x
->wait
, &wait
);
3878 return -ERESTARTSYS
;
3880 __set_current_state(state
);
3881 spin_unlock_irq(&x
->wait
.lock
);
3882 timeout
= schedule_timeout(timeout
);
3883 spin_lock_irq(&x
->wait
.lock
);
3885 __remove_wait_queue(&x
->wait
, &wait
);
3889 __remove_wait_queue(&x
->wait
, &wait
);
3896 wait_for_common(struct completion
*x
, long timeout
, int state
)
3900 spin_lock_irq(&x
->wait
.lock
);
3901 timeout
= do_wait_for_common(x
, timeout
, state
);
3902 spin_unlock_irq(&x
->wait
.lock
);
3906 void __sched
wait_for_completion(struct completion
*x
)
3908 wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_UNINTERRUPTIBLE
);
3910 EXPORT_SYMBOL(wait_for_completion
);
3912 unsigned long __sched
3913 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3915 return wait_for_common(x
, timeout
, TASK_UNINTERRUPTIBLE
);
3917 EXPORT_SYMBOL(wait_for_completion_timeout
);
3919 int __sched
wait_for_completion_interruptible(struct completion
*x
)
3921 long t
= wait_for_common(x
, MAX_SCHEDULE_TIMEOUT
, TASK_INTERRUPTIBLE
);
3922 if (t
== -ERESTARTSYS
)
3926 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3928 unsigned long __sched
3929 wait_for_completion_interruptible_timeout(struct completion
*x
,
3930 unsigned long timeout
)
3932 return wait_for_common(x
, timeout
, TASK_INTERRUPTIBLE
);
3934 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3937 sleep_on_common(wait_queue_head_t
*q
, int state
, long timeout
)
3939 unsigned long flags
;
3942 init_waitqueue_entry(&wait
, current
);
3944 __set_current_state(state
);
3946 spin_lock_irqsave(&q
->lock
, flags
);
3947 __add_wait_queue(q
, &wait
);
3948 spin_unlock(&q
->lock
);
3949 timeout
= schedule_timeout(timeout
);
3950 spin_lock_irq(&q
->lock
);
3951 __remove_wait_queue(q
, &wait
);
3952 spin_unlock_irqrestore(&q
->lock
, flags
);
3957 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3959 sleep_on_common(q
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3961 EXPORT_SYMBOL(interruptible_sleep_on
);
3964 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3966 return sleep_on_common(q
, TASK_INTERRUPTIBLE
, timeout
);
3968 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3970 void __sched
sleep_on(wait_queue_head_t
*q
)
3972 sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
3974 EXPORT_SYMBOL(sleep_on
);
3976 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3978 return sleep_on_common(q
, TASK_UNINTERRUPTIBLE
, timeout
);
3980 EXPORT_SYMBOL(sleep_on_timeout
);
3982 #ifdef CONFIG_RT_MUTEXES
3985 * rt_mutex_setprio - set the current priority of a task
3987 * @prio: prio value (kernel-internal form)
3989 * This function changes the 'effective' priority of a task. It does
3990 * not touch ->normal_prio like __setscheduler().
3992 * Used by the rt_mutex code to implement priority inheritance logic.
3994 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3996 unsigned long flags
;
3997 int oldprio
, on_rq
, running
;
4000 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4002 rq
= task_rq_lock(p
, &flags
);
4003 update_rq_clock(rq
);
4006 on_rq
= p
->se
.on_rq
;
4007 running
= task_running(rq
, p
);
4009 dequeue_task(rq
, p
, 0);
4011 p
->sched_class
->put_prev_task(rq
, p
);
4015 p
->sched_class
= &rt_sched_class
;
4017 p
->sched_class
= &fair_sched_class
;
4023 p
->sched_class
->set_curr_task(rq
);
4024 enqueue_task(rq
, p
, 0);
4026 * Reschedule if we are currently running on this runqueue and
4027 * our priority decreased, or if we are not currently running on
4028 * this runqueue and our priority is higher than the current's
4031 if (p
->prio
> oldprio
)
4032 resched_task(rq
->curr
);
4034 check_preempt_curr(rq
, p
);
4037 task_rq_unlock(rq
, &flags
);
4042 void set_user_nice(struct task_struct
*p
, long nice
)
4044 int old_prio
, delta
, on_rq
;
4045 unsigned long flags
;
4048 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4051 * We have to be careful, if called from sys_setpriority(),
4052 * the task might be in the middle of scheduling on another CPU.
4054 rq
= task_rq_lock(p
, &flags
);
4055 update_rq_clock(rq
);
4057 * The RT priorities are set via sched_setscheduler(), but we still
4058 * allow the 'normal' nice value to be set - but as expected
4059 * it wont have any effect on scheduling until the task is
4060 * SCHED_FIFO/SCHED_RR:
4062 if (task_has_rt_policy(p
)) {
4063 p
->static_prio
= NICE_TO_PRIO(nice
);
4066 on_rq
= p
->se
.on_rq
;
4068 dequeue_task(rq
, p
, 0);
4072 p
->static_prio
= NICE_TO_PRIO(nice
);
4075 p
->prio
= effective_prio(p
);
4076 delta
= p
->prio
- old_prio
;
4079 enqueue_task(rq
, p
, 0);
4082 * If the task increased its priority or is running and
4083 * lowered its priority, then reschedule its CPU:
4085 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4086 resched_task(rq
->curr
);
4089 task_rq_unlock(rq
, &flags
);
4091 EXPORT_SYMBOL(set_user_nice
);
4094 * can_nice - check if a task can reduce its nice value
4098 int can_nice(const struct task_struct
*p
, const int nice
)
4100 /* convert nice value [19,-20] to rlimit style value [1,40] */
4101 int nice_rlim
= 20 - nice
;
4103 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4104 capable(CAP_SYS_NICE
));
4107 #ifdef __ARCH_WANT_SYS_NICE
4110 * sys_nice - change the priority of the current process.
4111 * @increment: priority increment
4113 * sys_setpriority is a more generic, but much slower function that
4114 * does similar things.
4116 asmlinkage
long sys_nice(int increment
)
4121 * Setpriority might change our priority at the same moment.
4122 * We don't have to worry. Conceptually one call occurs first
4123 * and we have a single winner.
4125 if (increment
< -40)
4130 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4136 if (increment
< 0 && !can_nice(current
, nice
))
4139 retval
= security_task_setnice(current
, nice
);
4143 set_user_nice(current
, nice
);
4150 * task_prio - return the priority value of a given task.
4151 * @p: the task in question.
4153 * This is the priority value as seen by users in /proc.
4154 * RT tasks are offset by -200. Normal tasks are centered
4155 * around 0, value goes from -16 to +15.
4157 int task_prio(const struct task_struct
*p
)
4159 return p
->prio
- MAX_RT_PRIO
;
4163 * task_nice - return the nice value of a given task.
4164 * @p: the task in question.
4166 int task_nice(const struct task_struct
*p
)
4168 return TASK_NICE(p
);
4170 EXPORT_SYMBOL_GPL(task_nice
);
4173 * idle_cpu - is a given cpu idle currently?
4174 * @cpu: the processor in question.
4176 int idle_cpu(int cpu
)
4178 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4182 * idle_task - return the idle task for a given cpu.
4183 * @cpu: the processor in question.
4185 struct task_struct
*idle_task(int cpu
)
4187 return cpu_rq(cpu
)->idle
;
4191 * find_process_by_pid - find a process with a matching PID value.
4192 * @pid: the pid in question.
4194 static struct task_struct
*find_process_by_pid(pid_t pid
)
4196 return pid
? find_task_by_vpid(pid
) : current
;
4199 /* Actually do priority change: must hold rq lock. */
4201 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4203 BUG_ON(p
->se
.on_rq
);
4206 switch (p
->policy
) {
4210 p
->sched_class
= &fair_sched_class
;
4214 p
->sched_class
= &rt_sched_class
;
4218 p
->rt_priority
= prio
;
4219 p
->normal_prio
= normal_prio(p
);
4220 /* we are holding p->pi_lock already */
4221 p
->prio
= rt_mutex_getprio(p
);
4226 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4227 * @p: the task in question.
4228 * @policy: new policy.
4229 * @param: structure containing the new RT priority.
4231 * NOTE that the task may be already dead.
4233 int sched_setscheduler(struct task_struct
*p
, int policy
,
4234 struct sched_param
*param
)
4236 int retval
, oldprio
, oldpolicy
= -1, on_rq
, running
;
4237 unsigned long flags
;
4240 /* may grab non-irq protected spin_locks */
4241 BUG_ON(in_interrupt());
4243 /* double check policy once rq lock held */
4245 policy
= oldpolicy
= p
->policy
;
4246 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4247 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4248 policy
!= SCHED_IDLE
)
4251 * Valid priorities for SCHED_FIFO and SCHED_RR are
4252 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4253 * SCHED_BATCH and SCHED_IDLE is 0.
4255 if (param
->sched_priority
< 0 ||
4256 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4257 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4259 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4263 * Allow unprivileged RT tasks to decrease priority:
4265 if (!capable(CAP_SYS_NICE
)) {
4266 if (rt_policy(policy
)) {
4267 unsigned long rlim_rtprio
;
4269 if (!lock_task_sighand(p
, &flags
))
4271 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4272 unlock_task_sighand(p
, &flags
);
4274 /* can't set/change the rt policy */
4275 if (policy
!= p
->policy
&& !rlim_rtprio
)
4278 /* can't increase priority */
4279 if (param
->sched_priority
> p
->rt_priority
&&
4280 param
->sched_priority
> rlim_rtprio
)
4284 * Like positive nice levels, dont allow tasks to
4285 * move out of SCHED_IDLE either:
4287 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4290 /* can't change other user's priorities */
4291 if ((current
->euid
!= p
->euid
) &&
4292 (current
->euid
!= p
->uid
))
4296 retval
= security_task_setscheduler(p
, policy
, param
);
4300 * make sure no PI-waiters arrive (or leave) while we are
4301 * changing the priority of the task:
4303 spin_lock_irqsave(&p
->pi_lock
, flags
);
4305 * To be able to change p->policy safely, the apropriate
4306 * runqueue lock must be held.
4308 rq
= __task_rq_lock(p
);
4309 /* recheck policy now with rq lock held */
4310 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4311 policy
= oldpolicy
= -1;
4312 __task_rq_unlock(rq
);
4313 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4316 update_rq_clock(rq
);
4317 on_rq
= p
->se
.on_rq
;
4318 running
= task_running(rq
, p
);
4320 deactivate_task(rq
, p
, 0);
4322 p
->sched_class
->put_prev_task(rq
, p
);
4326 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4330 p
->sched_class
->set_curr_task(rq
);
4331 activate_task(rq
, p
, 0);
4333 * Reschedule if we are currently running on this runqueue and
4334 * our priority decreased, or if we are not currently running on
4335 * this runqueue and our priority is higher than the current's
4338 if (p
->prio
> oldprio
)
4339 resched_task(rq
->curr
);
4341 check_preempt_curr(rq
, p
);
4344 __task_rq_unlock(rq
);
4345 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4347 rt_mutex_adjust_pi(p
);
4351 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4354 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4356 struct sched_param lparam
;
4357 struct task_struct
*p
;
4360 if (!param
|| pid
< 0)
4362 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4367 p
= find_process_by_pid(pid
);
4369 retval
= sched_setscheduler(p
, policy
, &lparam
);
4376 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4377 * @pid: the pid in question.
4378 * @policy: new policy.
4379 * @param: structure containing the new RT priority.
4381 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
4382 struct sched_param __user
*param
)
4384 /* negative values for policy are not valid */
4388 return do_sched_setscheduler(pid
, policy
, param
);
4392 * sys_sched_setparam - set/change the RT priority of a thread
4393 * @pid: the pid in question.
4394 * @param: structure containing the new RT priority.
4396 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4398 return do_sched_setscheduler(pid
, -1, param
);
4402 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4403 * @pid: the pid in question.
4405 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4407 struct task_struct
*p
;
4414 read_lock(&tasklist_lock
);
4415 p
= find_process_by_pid(pid
);
4417 retval
= security_task_getscheduler(p
);
4421 read_unlock(&tasklist_lock
);
4426 * sys_sched_getscheduler - get the RT priority of a thread
4427 * @pid: the pid in question.
4428 * @param: structure containing the RT priority.
4430 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4432 struct sched_param lp
;
4433 struct task_struct
*p
;
4436 if (!param
|| pid
< 0)
4439 read_lock(&tasklist_lock
);
4440 p
= find_process_by_pid(pid
);
4445 retval
= security_task_getscheduler(p
);
4449 lp
.sched_priority
= p
->rt_priority
;
4450 read_unlock(&tasklist_lock
);
4453 * This one might sleep, we cannot do it with a spinlock held ...
4455 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4460 read_unlock(&tasklist_lock
);
4464 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4466 cpumask_t cpus_allowed
;
4467 struct task_struct
*p
;
4470 mutex_lock(&sched_hotcpu_mutex
);
4471 read_lock(&tasklist_lock
);
4473 p
= find_process_by_pid(pid
);
4475 read_unlock(&tasklist_lock
);
4476 mutex_unlock(&sched_hotcpu_mutex
);
4481 * It is not safe to call set_cpus_allowed with the
4482 * tasklist_lock held. We will bump the task_struct's
4483 * usage count and then drop tasklist_lock.
4486 read_unlock(&tasklist_lock
);
4489 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4490 !capable(CAP_SYS_NICE
))
4493 retval
= security_task_setscheduler(p
, 0, NULL
);
4497 cpus_allowed
= cpuset_cpus_allowed(p
);
4498 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4500 retval
= set_cpus_allowed(p
, new_mask
);
4503 cpus_allowed
= cpuset_cpus_allowed(p
);
4504 if (!cpus_subset(new_mask
, cpus_allowed
)) {
4506 * We must have raced with a concurrent cpuset
4507 * update. Just reset the cpus_allowed to the
4508 * cpuset's cpus_allowed
4510 new_mask
= cpus_allowed
;
4516 mutex_unlock(&sched_hotcpu_mutex
);
4520 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4521 cpumask_t
*new_mask
)
4523 if (len
< sizeof(cpumask_t
)) {
4524 memset(new_mask
, 0, sizeof(cpumask_t
));
4525 } else if (len
> sizeof(cpumask_t
)) {
4526 len
= sizeof(cpumask_t
);
4528 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4532 * sys_sched_setaffinity - set the cpu affinity of a process
4533 * @pid: pid of the process
4534 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4535 * @user_mask_ptr: user-space pointer to the new cpu mask
4537 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4538 unsigned long __user
*user_mask_ptr
)
4543 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4547 return sched_setaffinity(pid
, new_mask
);
4551 * Represents all cpu's present in the system
4552 * In systems capable of hotplug, this map could dynamically grow
4553 * as new cpu's are detected in the system via any platform specific
4554 * method, such as ACPI for e.g.
4557 cpumask_t cpu_present_map __read_mostly
;
4558 EXPORT_SYMBOL(cpu_present_map
);
4561 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4562 EXPORT_SYMBOL(cpu_online_map
);
4564 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4565 EXPORT_SYMBOL(cpu_possible_map
);
4568 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4570 struct task_struct
*p
;
4573 mutex_lock(&sched_hotcpu_mutex
);
4574 read_lock(&tasklist_lock
);
4577 p
= find_process_by_pid(pid
);
4581 retval
= security_task_getscheduler(p
);
4585 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4588 read_unlock(&tasklist_lock
);
4589 mutex_unlock(&sched_hotcpu_mutex
);
4595 * sys_sched_getaffinity - get the cpu affinity of a process
4596 * @pid: pid of the process
4597 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4598 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4600 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4601 unsigned long __user
*user_mask_ptr
)
4606 if (len
< sizeof(cpumask_t
))
4609 ret
= sched_getaffinity(pid
, &mask
);
4613 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4616 return sizeof(cpumask_t
);
4620 * sys_sched_yield - yield the current processor to other threads.
4622 * This function yields the current CPU to other tasks. If there are no
4623 * other threads running on this CPU then this function will return.
4625 asmlinkage
long sys_sched_yield(void)
4627 struct rq
*rq
= this_rq_lock();
4629 schedstat_inc(rq
, yld_count
);
4630 current
->sched_class
->yield_task(rq
);
4633 * Since we are going to call schedule() anyway, there's
4634 * no need to preempt or enable interrupts:
4636 __release(rq
->lock
);
4637 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4638 _raw_spin_unlock(&rq
->lock
);
4639 preempt_enable_no_resched();
4646 static void __cond_resched(void)
4648 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4649 __might_sleep(__FILE__
, __LINE__
);
4652 * The BKS might be reacquired before we have dropped
4653 * PREEMPT_ACTIVE, which could trigger a second
4654 * cond_resched() call.
4657 add_preempt_count(PREEMPT_ACTIVE
);
4659 sub_preempt_count(PREEMPT_ACTIVE
);
4660 } while (need_resched());
4663 int __sched
cond_resched(void)
4665 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4666 system_state
== SYSTEM_RUNNING
) {
4672 EXPORT_SYMBOL(cond_resched
);
4675 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4676 * call schedule, and on return reacquire the lock.
4678 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4679 * operations here to prevent schedule() from being called twice (once via
4680 * spin_unlock(), once by hand).
4682 int cond_resched_lock(spinlock_t
*lock
)
4686 if (need_lockbreak(lock
)) {
4692 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4693 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4694 _raw_spin_unlock(lock
);
4695 preempt_enable_no_resched();
4702 EXPORT_SYMBOL(cond_resched_lock
);
4704 int __sched
cond_resched_softirq(void)
4706 BUG_ON(!in_softirq());
4708 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4716 EXPORT_SYMBOL(cond_resched_softirq
);
4719 * yield - yield the current processor to other threads.
4721 * This is a shortcut for kernel-space yielding - it marks the
4722 * thread runnable and calls sys_sched_yield().
4724 void __sched
yield(void)
4726 set_current_state(TASK_RUNNING
);
4729 EXPORT_SYMBOL(yield
);
4732 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4733 * that process accounting knows that this is a task in IO wait state.
4735 * But don't do that if it is a deliberate, throttling IO wait (this task
4736 * has set its backing_dev_info: the queue against which it should throttle)
4738 void __sched
io_schedule(void)
4740 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4742 delayacct_blkio_start();
4743 atomic_inc(&rq
->nr_iowait
);
4745 atomic_dec(&rq
->nr_iowait
);
4746 delayacct_blkio_end();
4748 EXPORT_SYMBOL(io_schedule
);
4750 long __sched
io_schedule_timeout(long timeout
)
4752 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4755 delayacct_blkio_start();
4756 atomic_inc(&rq
->nr_iowait
);
4757 ret
= schedule_timeout(timeout
);
4758 atomic_dec(&rq
->nr_iowait
);
4759 delayacct_blkio_end();
4764 * sys_sched_get_priority_max - return maximum RT priority.
4765 * @policy: scheduling class.
4767 * this syscall returns the maximum rt_priority that can be used
4768 * by a given scheduling class.
4770 asmlinkage
long sys_sched_get_priority_max(int policy
)
4777 ret
= MAX_USER_RT_PRIO
-1;
4789 * sys_sched_get_priority_min - return minimum RT priority.
4790 * @policy: scheduling class.
4792 * this syscall returns the minimum rt_priority that can be used
4793 * by a given scheduling class.
4795 asmlinkage
long sys_sched_get_priority_min(int policy
)
4813 * sys_sched_rr_get_interval - return the default timeslice of a process.
4814 * @pid: pid of the process.
4815 * @interval: userspace pointer to the timeslice value.
4817 * this syscall writes the default timeslice value of a given process
4818 * into the user-space timespec buffer. A value of '0' means infinity.
4821 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4823 struct task_struct
*p
;
4824 unsigned int time_slice
;
4832 read_lock(&tasklist_lock
);
4833 p
= find_process_by_pid(pid
);
4837 retval
= security_task_getscheduler(p
);
4841 if (p
->policy
== SCHED_FIFO
)
4843 else if (p
->policy
== SCHED_RR
)
4844 time_slice
= DEF_TIMESLICE
;
4846 struct sched_entity
*se
= &p
->se
;
4847 unsigned long flags
;
4850 rq
= task_rq_lock(p
, &flags
);
4851 time_slice
= NS_TO_JIFFIES(sched_slice(cfs_rq_of(se
), se
));
4852 task_rq_unlock(rq
, &flags
);
4854 read_unlock(&tasklist_lock
);
4855 jiffies_to_timespec(time_slice
, &t
);
4856 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4860 read_unlock(&tasklist_lock
);
4864 static const char stat_nam
[] = "RSDTtZX";
4866 static void show_task(struct task_struct
*p
)
4868 unsigned long free
= 0;
4871 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4872 printk(KERN_INFO
"%-13.13s %c", p
->comm
,
4873 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4874 #if BITS_PER_LONG == 32
4875 if (state
== TASK_RUNNING
)
4876 printk(KERN_CONT
" running ");
4878 printk(KERN_CONT
" %08lx ", thread_saved_pc(p
));
4880 if (state
== TASK_RUNNING
)
4881 printk(KERN_CONT
" running task ");
4883 printk(KERN_CONT
" %016lx ", thread_saved_pc(p
));
4885 #ifdef CONFIG_DEBUG_STACK_USAGE
4887 unsigned long *n
= end_of_stack(p
);
4890 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4893 printk(KERN_CONT
"%5lu %5d %6d\n", free
,
4894 task_pid_nr(p
), task_pid_nr(p
->parent
));
4896 if (state
!= TASK_RUNNING
)
4897 show_stack(p
, NULL
);
4900 void show_state_filter(unsigned long state_filter
)
4902 struct task_struct
*g
, *p
;
4904 #if BITS_PER_LONG == 32
4906 " task PC stack pid father\n");
4909 " task PC stack pid father\n");
4911 read_lock(&tasklist_lock
);
4912 do_each_thread(g
, p
) {
4914 * reset the NMI-timeout, listing all files on a slow
4915 * console might take alot of time:
4917 touch_nmi_watchdog();
4918 if (!state_filter
|| (p
->state
& state_filter
))
4920 } while_each_thread(g
, p
);
4922 touch_all_softlockup_watchdogs();
4924 #ifdef CONFIG_SCHED_DEBUG
4925 sysrq_sched_debug_show();
4927 read_unlock(&tasklist_lock
);
4929 * Only show locks if all tasks are dumped:
4931 if (state_filter
== -1)
4932 debug_show_all_locks();
4935 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4937 idle
->sched_class
= &idle_sched_class
;
4941 * init_idle - set up an idle thread for a given CPU
4942 * @idle: task in question
4943 * @cpu: cpu the idle task belongs to
4945 * NOTE: this function does not set the idle thread's NEED_RESCHED
4946 * flag, to make booting more robust.
4948 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4950 struct rq
*rq
= cpu_rq(cpu
);
4951 unsigned long flags
;
4954 idle
->se
.exec_start
= sched_clock();
4956 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4957 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4958 __set_task_cpu(idle
, cpu
);
4960 spin_lock_irqsave(&rq
->lock
, flags
);
4961 rq
->curr
= rq
->idle
= idle
;
4962 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4965 spin_unlock_irqrestore(&rq
->lock
, flags
);
4967 /* Set the preempt count _outside_ the spinlocks! */
4968 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4969 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4971 task_thread_info(idle
)->preempt_count
= 0;
4974 * The idle tasks have their own, simple scheduling class:
4976 idle
->sched_class
= &idle_sched_class
;
4980 * In a system that switches off the HZ timer nohz_cpu_mask
4981 * indicates which cpus entered this state. This is used
4982 * in the rcu update to wait only for active cpus. For system
4983 * which do not switch off the HZ timer nohz_cpu_mask should
4984 * always be CPU_MASK_NONE.
4986 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4989 * Increase the granularity value when there are more CPUs,
4990 * because with more CPUs the 'effective latency' as visible
4991 * to users decreases. But the relationship is not linear,
4992 * so pick a second-best guess by going with the log2 of the
4995 * This idea comes from the SD scheduler of Con Kolivas:
4997 static inline void sched_init_granularity(void)
4999 unsigned int factor
= 1 + ilog2(num_online_cpus());
5000 const unsigned long limit
= 200000000;
5002 sysctl_sched_min_granularity
*= factor
;
5003 if (sysctl_sched_min_granularity
> limit
)
5004 sysctl_sched_min_granularity
= limit
;
5006 sysctl_sched_latency
*= factor
;
5007 if (sysctl_sched_latency
> limit
)
5008 sysctl_sched_latency
= limit
;
5010 sysctl_sched_wakeup_granularity
*= factor
;
5011 sysctl_sched_batch_wakeup_granularity
*= factor
;
5016 * This is how migration works:
5018 * 1) we queue a struct migration_req structure in the source CPU's
5019 * runqueue and wake up that CPU's migration thread.
5020 * 2) we down() the locked semaphore => thread blocks.
5021 * 3) migration thread wakes up (implicitly it forces the migrated
5022 * thread off the CPU)
5023 * 4) it gets the migration request and checks whether the migrated
5024 * task is still in the wrong runqueue.
5025 * 5) if it's in the wrong runqueue then the migration thread removes
5026 * it and puts it into the right queue.
5027 * 6) migration thread up()s the semaphore.
5028 * 7) we wake up and the migration is done.
5032 * Change a given task's CPU affinity. Migrate the thread to a
5033 * proper CPU and schedule it away if the CPU it's executing on
5034 * is removed from the allowed bitmask.
5036 * NOTE: the caller must have a valid reference to the task, the
5037 * task must not exit() & deallocate itself prematurely. The
5038 * call is not atomic; no spinlocks may be held.
5040 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5042 struct migration_req req
;
5043 unsigned long flags
;
5047 rq
= task_rq_lock(p
, &flags
);
5048 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5053 p
->cpus_allowed
= new_mask
;
5054 /* Can the task run on the task's current CPU? If so, we're done */
5055 if (cpu_isset(task_cpu(p
), new_mask
))
5058 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5059 /* Need help from migration thread: drop lock and wait. */
5060 task_rq_unlock(rq
, &flags
);
5061 wake_up_process(rq
->migration_thread
);
5062 wait_for_completion(&req
.done
);
5063 tlb_migrate_finish(p
->mm
);
5067 task_rq_unlock(rq
, &flags
);
5071 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5074 * Move (not current) task off this cpu, onto dest cpu. We're doing
5075 * this because either it can't run here any more (set_cpus_allowed()
5076 * away from this CPU, or CPU going down), or because we're
5077 * attempting to rebalance this task on exec (sched_exec).
5079 * So we race with normal scheduler movements, but that's OK, as long
5080 * as the task is no longer on this CPU.
5082 * Returns non-zero if task was successfully migrated.
5084 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5086 struct rq
*rq_dest
, *rq_src
;
5089 if (unlikely(cpu_is_offline(dest_cpu
)))
5092 rq_src
= cpu_rq(src_cpu
);
5093 rq_dest
= cpu_rq(dest_cpu
);
5095 double_rq_lock(rq_src
, rq_dest
);
5096 /* Already moved. */
5097 if (task_cpu(p
) != src_cpu
)
5099 /* Affinity changed (again). */
5100 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5103 on_rq
= p
->se
.on_rq
;
5105 deactivate_task(rq_src
, p
, 0);
5107 set_task_cpu(p
, dest_cpu
);
5109 activate_task(rq_dest
, p
, 0);
5110 check_preempt_curr(rq_dest
, p
);
5114 double_rq_unlock(rq_src
, rq_dest
);
5119 * migration_thread - this is a highprio system thread that performs
5120 * thread migration by bumping thread off CPU then 'pushing' onto
5123 static int migration_thread(void *data
)
5125 int cpu
= (long)data
;
5129 BUG_ON(rq
->migration_thread
!= current
);
5131 set_current_state(TASK_INTERRUPTIBLE
);
5132 while (!kthread_should_stop()) {
5133 struct migration_req
*req
;
5134 struct list_head
*head
;
5136 spin_lock_irq(&rq
->lock
);
5138 if (cpu_is_offline(cpu
)) {
5139 spin_unlock_irq(&rq
->lock
);
5143 if (rq
->active_balance
) {
5144 active_load_balance(rq
, cpu
);
5145 rq
->active_balance
= 0;
5148 head
= &rq
->migration_queue
;
5150 if (list_empty(head
)) {
5151 spin_unlock_irq(&rq
->lock
);
5153 set_current_state(TASK_INTERRUPTIBLE
);
5156 req
= list_entry(head
->next
, struct migration_req
, list
);
5157 list_del_init(head
->next
);
5159 spin_unlock(&rq
->lock
);
5160 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5163 complete(&req
->done
);
5165 __set_current_state(TASK_RUNNING
);
5169 /* Wait for kthread_stop */
5170 set_current_state(TASK_INTERRUPTIBLE
);
5171 while (!kthread_should_stop()) {
5173 set_current_state(TASK_INTERRUPTIBLE
);
5175 __set_current_state(TASK_RUNNING
);
5179 #ifdef CONFIG_HOTPLUG_CPU
5181 static int __migrate_task_irq(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5185 local_irq_disable();
5186 ret
= __migrate_task(p
, src_cpu
, dest_cpu
);
5192 * Figure out where task on dead CPU should go, use force if necessary.
5193 * NOTE: interrupts should be disabled by the caller
5195 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5197 unsigned long flags
;
5204 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5205 cpus_and(mask
, mask
, p
->cpus_allowed
);
5206 dest_cpu
= any_online_cpu(mask
);
5208 /* On any allowed CPU? */
5209 if (dest_cpu
== NR_CPUS
)
5210 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5212 /* No more Mr. Nice Guy. */
5213 if (dest_cpu
== NR_CPUS
) {
5214 cpumask_t cpus_allowed
= cpuset_cpus_allowed_locked(p
);
5216 * Try to stay on the same cpuset, where the
5217 * current cpuset may be a subset of all cpus.
5218 * The cpuset_cpus_allowed_locked() variant of
5219 * cpuset_cpus_allowed() will not block. It must be
5220 * called within calls to cpuset_lock/cpuset_unlock.
5222 rq
= task_rq_lock(p
, &flags
);
5223 p
->cpus_allowed
= cpus_allowed
;
5224 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5225 task_rq_unlock(rq
, &flags
);
5228 * Don't tell them about moving exiting tasks or
5229 * kernel threads (both mm NULL), since they never
5232 if (p
->mm
&& printk_ratelimit())
5233 printk(KERN_INFO
"process %d (%s) no "
5234 "longer affine to cpu%d\n",
5235 task_pid_nr(p
), p
->comm
, dead_cpu
);
5237 } while (!__migrate_task_irq(p
, dead_cpu
, dest_cpu
));
5241 * While a dead CPU has no uninterruptible tasks queued at this point,
5242 * it might still have a nonzero ->nr_uninterruptible counter, because
5243 * for performance reasons the counter is not stricly tracking tasks to
5244 * their home CPUs. So we just add the counter to another CPU's counter,
5245 * to keep the global sum constant after CPU-down:
5247 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5249 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5250 unsigned long flags
;
5252 local_irq_save(flags
);
5253 double_rq_lock(rq_src
, rq_dest
);
5254 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5255 rq_src
->nr_uninterruptible
= 0;
5256 double_rq_unlock(rq_src
, rq_dest
);
5257 local_irq_restore(flags
);
5260 /* Run through task list and migrate tasks from the dead cpu. */
5261 static void migrate_live_tasks(int src_cpu
)
5263 struct task_struct
*p
, *t
;
5265 read_lock(&tasklist_lock
);
5267 do_each_thread(t
, p
) {
5271 if (task_cpu(p
) == src_cpu
)
5272 move_task_off_dead_cpu(src_cpu
, p
);
5273 } while_each_thread(t
, p
);
5275 read_unlock(&tasklist_lock
);
5279 * activate_idle_task - move idle task to the _front_ of runqueue.
5281 static void activate_idle_task(struct task_struct
*p
, struct rq
*rq
)
5283 update_rq_clock(rq
);
5285 if (p
->state
== TASK_UNINTERRUPTIBLE
)
5286 rq
->nr_uninterruptible
--;
5288 enqueue_task(rq
, p
, 0);
5289 inc_nr_running(p
, rq
);
5293 * Schedules idle task to be the next runnable task on current CPU.
5294 * It does so by boosting its priority to highest possible and adding it to
5295 * the _front_ of the runqueue. Used by CPU offline code.
5297 void sched_idle_next(void)
5299 int this_cpu
= smp_processor_id();
5300 struct rq
*rq
= cpu_rq(this_cpu
);
5301 struct task_struct
*p
= rq
->idle
;
5302 unsigned long flags
;
5304 /* cpu has to be offline */
5305 BUG_ON(cpu_online(this_cpu
));
5308 * Strictly not necessary since rest of the CPUs are stopped by now
5309 * and interrupts disabled on the current cpu.
5311 spin_lock_irqsave(&rq
->lock
, flags
);
5313 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5315 /* Add idle task to the _front_ of its priority queue: */
5316 activate_idle_task(p
, rq
);
5318 spin_unlock_irqrestore(&rq
->lock
, flags
);
5322 * Ensures that the idle task is using init_mm right before its cpu goes
5325 void idle_task_exit(void)
5327 struct mm_struct
*mm
= current
->active_mm
;
5329 BUG_ON(cpu_online(smp_processor_id()));
5332 switch_mm(mm
, &init_mm
, current
);
5336 /* called under rq->lock with disabled interrupts */
5337 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5339 struct rq
*rq
= cpu_rq(dead_cpu
);
5341 /* Must be exiting, otherwise would be on tasklist. */
5342 BUG_ON(!p
->exit_state
);
5344 /* Cannot have done final schedule yet: would have vanished. */
5345 BUG_ON(p
->state
== TASK_DEAD
);
5350 * Drop lock around migration; if someone else moves it,
5351 * that's OK. No task can be added to this CPU, so iteration is
5354 spin_unlock_irq(&rq
->lock
);
5355 move_task_off_dead_cpu(dead_cpu
, p
);
5356 spin_lock_irq(&rq
->lock
);
5361 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5362 static void migrate_dead_tasks(unsigned int dead_cpu
)
5364 struct rq
*rq
= cpu_rq(dead_cpu
);
5365 struct task_struct
*next
;
5368 if (!rq
->nr_running
)
5370 update_rq_clock(rq
);
5371 next
= pick_next_task(rq
, rq
->curr
);
5374 migrate_dead(dead_cpu
, next
);
5378 #endif /* CONFIG_HOTPLUG_CPU */
5380 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5382 static struct ctl_table sd_ctl_dir
[] = {
5384 .procname
= "sched_domain",
5390 static struct ctl_table sd_ctl_root
[] = {
5392 .ctl_name
= CTL_KERN
,
5393 .procname
= "kernel",
5395 .child
= sd_ctl_dir
,
5400 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5402 struct ctl_table
*entry
=
5403 kcalloc(n
, sizeof(struct ctl_table
), GFP_KERNEL
);
5408 static void sd_free_ctl_entry(struct ctl_table
**tablep
)
5410 struct ctl_table
*entry
;
5413 * In the intermediate directories, both the child directory and
5414 * procname are dynamically allocated and could fail but the mode
5415 * will always be set. In the lowest directory the names are
5416 * static strings and all have proc handlers.
5418 for (entry
= *tablep
; entry
->mode
; entry
++) {
5420 sd_free_ctl_entry(&entry
->child
);
5421 if (entry
->proc_handler
== NULL
)
5422 kfree(entry
->procname
);
5430 set_table_entry(struct ctl_table
*entry
,
5431 const char *procname
, void *data
, int maxlen
,
5432 mode_t mode
, proc_handler
*proc_handler
)
5434 entry
->procname
= procname
;
5436 entry
->maxlen
= maxlen
;
5438 entry
->proc_handler
= proc_handler
;
5441 static struct ctl_table
*
5442 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5444 struct ctl_table
*table
= sd_alloc_ctl_entry(12);
5449 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5450 sizeof(long), 0644, proc_doulongvec_minmax
);
5451 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5452 sizeof(long), 0644, proc_doulongvec_minmax
);
5453 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5454 sizeof(int), 0644, proc_dointvec_minmax
);
5455 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5456 sizeof(int), 0644, proc_dointvec_minmax
);
5457 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5458 sizeof(int), 0644, proc_dointvec_minmax
);
5459 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5460 sizeof(int), 0644, proc_dointvec_minmax
);
5461 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5462 sizeof(int), 0644, proc_dointvec_minmax
);
5463 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5464 sizeof(int), 0644, proc_dointvec_minmax
);
5465 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5466 sizeof(int), 0644, proc_dointvec_minmax
);
5467 set_table_entry(&table
[9], "cache_nice_tries",
5468 &sd
->cache_nice_tries
,
5469 sizeof(int), 0644, proc_dointvec_minmax
);
5470 set_table_entry(&table
[10], "flags", &sd
->flags
,
5471 sizeof(int), 0644, proc_dointvec_minmax
);
5472 /* &table[11] is terminator */
5477 static ctl_table
* sd_alloc_ctl_cpu_table(int cpu
)
5479 struct ctl_table
*entry
, *table
;
5480 struct sched_domain
*sd
;
5481 int domain_num
= 0, i
;
5484 for_each_domain(cpu
, sd
)
5486 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5491 for_each_domain(cpu
, sd
) {
5492 snprintf(buf
, 32, "domain%d", i
);
5493 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5495 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5502 static struct ctl_table_header
*sd_sysctl_header
;
5503 static void register_sched_domain_sysctl(void)
5505 int i
, cpu_num
= num_online_cpus();
5506 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5509 WARN_ON(sd_ctl_dir
[0].child
);
5510 sd_ctl_dir
[0].child
= entry
;
5515 for_each_online_cpu(i
) {
5516 snprintf(buf
, 32, "cpu%d", i
);
5517 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5519 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5523 WARN_ON(sd_sysctl_header
);
5524 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5527 /* may be called multiple times per register */
5528 static void unregister_sched_domain_sysctl(void)
5530 if (sd_sysctl_header
)
5531 unregister_sysctl_table(sd_sysctl_header
);
5532 sd_sysctl_header
= NULL
;
5533 if (sd_ctl_dir
[0].child
)
5534 sd_free_ctl_entry(&sd_ctl_dir
[0].child
);
5537 static void register_sched_domain_sysctl(void)
5540 static void unregister_sched_domain_sysctl(void)
5546 * migration_call - callback that gets triggered when a CPU is added.
5547 * Here we can start up the necessary migration thread for the new CPU.
5549 static int __cpuinit
5550 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5552 struct task_struct
*p
;
5553 int cpu
= (long)hcpu
;
5554 unsigned long flags
;
5558 case CPU_LOCK_ACQUIRE
:
5559 mutex_lock(&sched_hotcpu_mutex
);
5562 case CPU_UP_PREPARE
:
5563 case CPU_UP_PREPARE_FROZEN
:
5564 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5567 kthread_bind(p
, cpu
);
5568 /* Must be high prio: stop_machine expects to yield to it. */
5569 rq
= task_rq_lock(p
, &flags
);
5570 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5571 task_rq_unlock(rq
, &flags
);
5572 cpu_rq(cpu
)->migration_thread
= p
;
5576 case CPU_ONLINE_FROZEN
:
5577 /* Strictly unnecessary, as first user will wake it. */
5578 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5581 #ifdef CONFIG_HOTPLUG_CPU
5582 case CPU_UP_CANCELED
:
5583 case CPU_UP_CANCELED_FROZEN
:
5584 if (!cpu_rq(cpu
)->migration_thread
)
5586 /* Unbind it from offline cpu so it can run. Fall thru. */
5587 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5588 any_online_cpu(cpu_online_map
));
5589 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5590 cpu_rq(cpu
)->migration_thread
= NULL
;
5594 case CPU_DEAD_FROZEN
:
5595 cpuset_lock(); /* around calls to cpuset_cpus_allowed_lock() */
5596 migrate_live_tasks(cpu
);
5598 kthread_stop(rq
->migration_thread
);
5599 rq
->migration_thread
= NULL
;
5600 /* Idle task back to normal (off runqueue, low prio) */
5601 spin_lock_irq(&rq
->lock
);
5602 update_rq_clock(rq
);
5603 deactivate_task(rq
, rq
->idle
, 0);
5604 rq
->idle
->static_prio
= MAX_PRIO
;
5605 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5606 rq
->idle
->sched_class
= &idle_sched_class
;
5607 migrate_dead_tasks(cpu
);
5608 spin_unlock_irq(&rq
->lock
);
5610 migrate_nr_uninterruptible(rq
);
5611 BUG_ON(rq
->nr_running
!= 0);
5613 /* No need to migrate the tasks: it was best-effort if
5614 * they didn't take sched_hotcpu_mutex. Just wake up
5615 * the requestors. */
5616 spin_lock_irq(&rq
->lock
);
5617 while (!list_empty(&rq
->migration_queue
)) {
5618 struct migration_req
*req
;
5620 req
= list_entry(rq
->migration_queue
.next
,
5621 struct migration_req
, list
);
5622 list_del_init(&req
->list
);
5623 complete(&req
->done
);
5625 spin_unlock_irq(&rq
->lock
);
5628 case CPU_LOCK_RELEASE
:
5629 mutex_unlock(&sched_hotcpu_mutex
);
5635 /* Register at highest priority so that task migration (migrate_all_tasks)
5636 * happens before everything else.
5638 static struct notifier_block __cpuinitdata migration_notifier
= {
5639 .notifier_call
= migration_call
,
5643 void __init
migration_init(void)
5645 void *cpu
= (void *)(long)smp_processor_id();
5648 /* Start one for the boot CPU: */
5649 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5650 BUG_ON(err
== NOTIFY_BAD
);
5651 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5652 register_cpu_notifier(&migration_notifier
);
5658 /* Number of possible processor ids */
5659 int nr_cpu_ids __read_mostly
= NR_CPUS
;
5660 EXPORT_SYMBOL(nr_cpu_ids
);
5662 #ifdef CONFIG_SCHED_DEBUG
5664 static int sched_domain_debug_one(struct sched_domain
*sd
, int cpu
, int level
)
5666 struct sched_group
*group
= sd
->groups
;
5667 cpumask_t groupmask
;
5670 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5671 cpus_clear(groupmask
);
5673 printk(KERN_DEBUG
"%*s domain %d: ", level
, "", level
);
5675 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5676 printk("does not load-balance\n");
5678 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5683 printk(KERN_CONT
"span %s\n", str
);
5685 if (!cpu_isset(cpu
, sd
->span
)) {
5686 printk(KERN_ERR
"ERROR: domain->span does not contain "
5689 if (!cpu_isset(cpu
, group
->cpumask
)) {
5690 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5694 printk(KERN_DEBUG
"%*s groups:", level
+ 1, "");
5698 printk(KERN_ERR
"ERROR: group is NULL\n");
5702 if (!group
->__cpu_power
) {
5703 printk(KERN_CONT
"\n");
5704 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5709 if (!cpus_weight(group
->cpumask
)) {
5710 printk(KERN_CONT
"\n");
5711 printk(KERN_ERR
"ERROR: empty group\n");
5715 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5716 printk(KERN_CONT
"\n");
5717 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5721 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5723 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5724 printk(KERN_CONT
" %s", str
);
5726 group
= group
->next
;
5727 } while (group
!= sd
->groups
);
5728 printk(KERN_CONT
"\n");
5730 if (!cpus_equal(sd
->span
, groupmask
))
5731 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
5733 if (sd
->parent
&& !cpus_subset(groupmask
, sd
->parent
->span
))
5734 printk(KERN_ERR
"ERROR: parent span is not a superset "
5735 "of domain->span\n");
5739 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5744 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5748 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5751 if (sched_domain_debug_one(sd
, cpu
, level
))
5760 # define sched_domain_debug(sd, cpu) do { } while (0)
5763 static int sd_degenerate(struct sched_domain
*sd
)
5765 if (cpus_weight(sd
->span
) == 1)
5768 /* Following flags need at least 2 groups */
5769 if (sd
->flags
& (SD_LOAD_BALANCE
|
5770 SD_BALANCE_NEWIDLE
|
5774 SD_SHARE_PKG_RESOURCES
)) {
5775 if (sd
->groups
!= sd
->groups
->next
)
5779 /* Following flags don't use groups */
5780 if (sd
->flags
& (SD_WAKE_IDLE
|
5789 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5791 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5793 if (sd_degenerate(parent
))
5796 if (!cpus_equal(sd
->span
, parent
->span
))
5799 /* Does parent contain flags not in child? */
5800 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5801 if (cflags
& SD_WAKE_AFFINE
)
5802 pflags
&= ~SD_WAKE_BALANCE
;
5803 /* Flags needing groups don't count if only 1 group in parent */
5804 if (parent
->groups
== parent
->groups
->next
) {
5805 pflags
&= ~(SD_LOAD_BALANCE
|
5806 SD_BALANCE_NEWIDLE
|
5810 SD_SHARE_PKG_RESOURCES
);
5812 if (~cflags
& pflags
)
5819 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5820 * hold the hotplug lock.
5822 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5824 struct rq
*rq
= cpu_rq(cpu
);
5825 struct sched_domain
*tmp
;
5827 /* Remove the sched domains which do not contribute to scheduling. */
5828 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5829 struct sched_domain
*parent
= tmp
->parent
;
5832 if (sd_parent_degenerate(tmp
, parent
)) {
5833 tmp
->parent
= parent
->parent
;
5835 parent
->parent
->child
= tmp
;
5839 if (sd
&& sd_degenerate(sd
)) {
5845 sched_domain_debug(sd
, cpu
);
5847 rcu_assign_pointer(rq
->sd
, sd
);
5850 /* cpus with isolated domains */
5851 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5853 /* Setup the mask of cpus configured for isolated domains */
5854 static int __init
isolated_cpu_setup(char *str
)
5856 int ints
[NR_CPUS
], i
;
5858 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5859 cpus_clear(cpu_isolated_map
);
5860 for (i
= 1; i
<= ints
[0]; i
++)
5861 if (ints
[i
] < NR_CPUS
)
5862 cpu_set(ints
[i
], cpu_isolated_map
);
5866 __setup("isolcpus=", isolated_cpu_setup
);
5869 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5870 * to a function which identifies what group(along with sched group) a CPU
5871 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5872 * (due to the fact that we keep track of groups covered with a cpumask_t).
5874 * init_sched_build_groups will build a circular linked list of the groups
5875 * covered by the given span, and will set each group's ->cpumask correctly,
5876 * and ->cpu_power to 0.
5879 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5880 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5881 struct sched_group
**sg
))
5883 struct sched_group
*first
= NULL
, *last
= NULL
;
5884 cpumask_t covered
= CPU_MASK_NONE
;
5887 for_each_cpu_mask(i
, span
) {
5888 struct sched_group
*sg
;
5889 int group
= group_fn(i
, cpu_map
, &sg
);
5892 if (cpu_isset(i
, covered
))
5895 sg
->cpumask
= CPU_MASK_NONE
;
5896 sg
->__cpu_power
= 0;
5898 for_each_cpu_mask(j
, span
) {
5899 if (group_fn(j
, cpu_map
, NULL
) != group
)
5902 cpu_set(j
, covered
);
5903 cpu_set(j
, sg
->cpumask
);
5914 #define SD_NODES_PER_DOMAIN 16
5919 * find_next_best_node - find the next node to include in a sched_domain
5920 * @node: node whose sched_domain we're building
5921 * @used_nodes: nodes already in the sched_domain
5923 * Find the next node to include in a given scheduling domain. Simply
5924 * finds the closest node not already in the @used_nodes map.
5926 * Should use nodemask_t.
5928 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5930 int i
, n
, val
, min_val
, best_node
= 0;
5934 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5935 /* Start at @node */
5936 n
= (node
+ i
) % MAX_NUMNODES
;
5938 if (!nr_cpus_node(n
))
5941 /* Skip already used nodes */
5942 if (test_bit(n
, used_nodes
))
5945 /* Simple min distance search */
5946 val
= node_distance(node
, n
);
5948 if (val
< min_val
) {
5954 set_bit(best_node
, used_nodes
);
5959 * sched_domain_node_span - get a cpumask for a node's sched_domain
5960 * @node: node whose cpumask we're constructing
5961 * @size: number of nodes to include in this span
5963 * Given a node, construct a good cpumask for its sched_domain to span. It
5964 * should be one that prevents unnecessary balancing, but also spreads tasks
5967 static cpumask_t
sched_domain_node_span(int node
)
5969 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5970 cpumask_t span
, nodemask
;
5974 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5976 nodemask
= node_to_cpumask(node
);
5977 cpus_or(span
, span
, nodemask
);
5978 set_bit(node
, used_nodes
);
5980 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5981 int next_node
= find_next_best_node(node
, used_nodes
);
5983 nodemask
= node_to_cpumask(next_node
);
5984 cpus_or(span
, span
, nodemask
);
5991 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
5994 * SMT sched-domains:
5996 #ifdef CONFIG_SCHED_SMT
5997 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5998 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6000 static int cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
,
6001 struct sched_group
**sg
)
6004 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6010 * multi-core sched-domains:
6012 #ifdef CONFIG_SCHED_MC
6013 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6014 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6017 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6018 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6019 struct sched_group
**sg
)
6022 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6023 cpus_and(mask
, mask
, *cpu_map
);
6024 group
= first_cpu(mask
);
6026 *sg
= &per_cpu(sched_group_core
, group
);
6029 #elif defined(CONFIG_SCHED_MC)
6030 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6031 struct sched_group
**sg
)
6034 *sg
= &per_cpu(sched_group_core
, cpu
);
6039 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6040 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6042 static int cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
,
6043 struct sched_group
**sg
)
6046 #ifdef CONFIG_SCHED_MC
6047 cpumask_t mask
= cpu_coregroup_map(cpu
);
6048 cpus_and(mask
, mask
, *cpu_map
);
6049 group
= first_cpu(mask
);
6050 #elif defined(CONFIG_SCHED_SMT)
6051 cpumask_t mask
= per_cpu(cpu_sibling_map
, cpu
);
6052 cpus_and(mask
, mask
, *cpu_map
);
6053 group
= first_cpu(mask
);
6058 *sg
= &per_cpu(sched_group_phys
, group
);
6064 * The init_sched_build_groups can't handle what we want to do with node
6065 * groups, so roll our own. Now each node has its own list of groups which
6066 * gets dynamically allocated.
6068 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6069 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6071 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6072 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6074 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6075 struct sched_group
**sg
)
6077 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6080 cpus_and(nodemask
, nodemask
, *cpu_map
);
6081 group
= first_cpu(nodemask
);
6084 *sg
= &per_cpu(sched_group_allnodes
, group
);
6088 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6090 struct sched_group
*sg
= group_head
;
6096 for_each_cpu_mask(j
, sg
->cpumask
) {
6097 struct sched_domain
*sd
;
6099 sd
= &per_cpu(phys_domains
, j
);
6100 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6102 * Only add "power" once for each
6108 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
6111 } while (sg
!= group_head
);
6116 /* Free memory allocated for various sched_group structures */
6117 static void free_sched_groups(const cpumask_t
*cpu_map
)
6121 for_each_cpu_mask(cpu
, *cpu_map
) {
6122 struct sched_group
**sched_group_nodes
6123 = sched_group_nodes_bycpu
[cpu
];
6125 if (!sched_group_nodes
)
6128 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6129 cpumask_t nodemask
= node_to_cpumask(i
);
6130 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6132 cpus_and(nodemask
, nodemask
, *cpu_map
);
6133 if (cpus_empty(nodemask
))
6143 if (oldsg
!= sched_group_nodes
[i
])
6146 kfree(sched_group_nodes
);
6147 sched_group_nodes_bycpu
[cpu
] = NULL
;
6151 static void free_sched_groups(const cpumask_t
*cpu_map
)
6157 * Initialize sched groups cpu_power.
6159 * cpu_power indicates the capacity of sched group, which is used while
6160 * distributing the load between different sched groups in a sched domain.
6161 * Typically cpu_power for all the groups in a sched domain will be same unless
6162 * there are asymmetries in the topology. If there are asymmetries, group
6163 * having more cpu_power will pickup more load compared to the group having
6166 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6167 * the maximum number of tasks a group can handle in the presence of other idle
6168 * or lightly loaded groups in the same sched domain.
6170 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6172 struct sched_domain
*child
;
6173 struct sched_group
*group
;
6175 WARN_ON(!sd
|| !sd
->groups
);
6177 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6182 sd
->groups
->__cpu_power
= 0;
6185 * For perf policy, if the groups in child domain share resources
6186 * (for example cores sharing some portions of the cache hierarchy
6187 * or SMT), then set this domain groups cpu_power such that each group
6188 * can handle only one task, when there are other idle groups in the
6189 * same sched domain.
6191 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6193 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6194 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
6199 * add cpu_power of each child group to this groups cpu_power
6201 group
= child
->groups
;
6203 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
6204 group
= group
->next
;
6205 } while (group
!= child
->groups
);
6209 * Build sched domains for a given set of cpus and attach the sched domains
6210 * to the individual cpus
6212 static int build_sched_domains(const cpumask_t
*cpu_map
)
6216 struct sched_group
**sched_group_nodes
= NULL
;
6217 int sd_allnodes
= 0;
6220 * Allocate the per-node list of sched groups
6222 sched_group_nodes
= kcalloc(MAX_NUMNODES
, sizeof(struct sched_group
*),
6224 if (!sched_group_nodes
) {
6225 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6228 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6232 * Set up domains for cpus specified by the cpu_map.
6234 for_each_cpu_mask(i
, *cpu_map
) {
6235 struct sched_domain
*sd
= NULL
, *p
;
6236 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6238 cpus_and(nodemask
, nodemask
, *cpu_map
);
6241 if (cpus_weight(*cpu_map
) >
6242 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6243 sd
= &per_cpu(allnodes_domains
, i
);
6244 *sd
= SD_ALLNODES_INIT
;
6245 sd
->span
= *cpu_map
;
6246 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6252 sd
= &per_cpu(node_domains
, i
);
6254 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6258 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6262 sd
= &per_cpu(phys_domains
, i
);
6264 sd
->span
= nodemask
;
6268 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6270 #ifdef CONFIG_SCHED_MC
6272 sd
= &per_cpu(core_domains
, i
);
6274 sd
->span
= cpu_coregroup_map(i
);
6275 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6278 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6281 #ifdef CONFIG_SCHED_SMT
6283 sd
= &per_cpu(cpu_domains
, i
);
6284 *sd
= SD_SIBLING_INIT
;
6285 sd
->span
= per_cpu(cpu_sibling_map
, i
);
6286 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6289 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6293 #ifdef CONFIG_SCHED_SMT
6294 /* Set up CPU (sibling) groups */
6295 for_each_cpu_mask(i
, *cpu_map
) {
6296 cpumask_t this_sibling_map
= per_cpu(cpu_sibling_map
, i
);
6297 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6298 if (i
!= first_cpu(this_sibling_map
))
6301 init_sched_build_groups(this_sibling_map
, cpu_map
,
6306 #ifdef CONFIG_SCHED_MC
6307 /* Set up multi-core groups */
6308 for_each_cpu_mask(i
, *cpu_map
) {
6309 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6310 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6311 if (i
!= first_cpu(this_core_map
))
6313 init_sched_build_groups(this_core_map
, cpu_map
,
6314 &cpu_to_core_group
);
6318 /* Set up physical groups */
6319 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6320 cpumask_t nodemask
= node_to_cpumask(i
);
6322 cpus_and(nodemask
, nodemask
, *cpu_map
);
6323 if (cpus_empty(nodemask
))
6326 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6330 /* Set up node groups */
6332 init_sched_build_groups(*cpu_map
, cpu_map
,
6333 &cpu_to_allnodes_group
);
6335 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6336 /* Set up node groups */
6337 struct sched_group
*sg
, *prev
;
6338 cpumask_t nodemask
= node_to_cpumask(i
);
6339 cpumask_t domainspan
;
6340 cpumask_t covered
= CPU_MASK_NONE
;
6343 cpus_and(nodemask
, nodemask
, *cpu_map
);
6344 if (cpus_empty(nodemask
)) {
6345 sched_group_nodes
[i
] = NULL
;
6349 domainspan
= sched_domain_node_span(i
);
6350 cpus_and(domainspan
, domainspan
, *cpu_map
);
6352 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6354 printk(KERN_WARNING
"Can not alloc domain group for "
6358 sched_group_nodes
[i
] = sg
;
6359 for_each_cpu_mask(j
, nodemask
) {
6360 struct sched_domain
*sd
;
6362 sd
= &per_cpu(node_domains
, j
);
6365 sg
->__cpu_power
= 0;
6366 sg
->cpumask
= nodemask
;
6368 cpus_or(covered
, covered
, nodemask
);
6371 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6372 cpumask_t tmp
, notcovered
;
6373 int n
= (i
+ j
) % MAX_NUMNODES
;
6375 cpus_complement(notcovered
, covered
);
6376 cpus_and(tmp
, notcovered
, *cpu_map
);
6377 cpus_and(tmp
, tmp
, domainspan
);
6378 if (cpus_empty(tmp
))
6381 nodemask
= node_to_cpumask(n
);
6382 cpus_and(tmp
, tmp
, nodemask
);
6383 if (cpus_empty(tmp
))
6386 sg
= kmalloc_node(sizeof(struct sched_group
),
6390 "Can not alloc domain group for node %d\n", j
);
6393 sg
->__cpu_power
= 0;
6395 sg
->next
= prev
->next
;
6396 cpus_or(covered
, covered
, tmp
);
6403 /* Calculate CPU power for physical packages and nodes */
6404 #ifdef CONFIG_SCHED_SMT
6405 for_each_cpu_mask(i
, *cpu_map
) {
6406 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6408 init_sched_groups_power(i
, sd
);
6411 #ifdef CONFIG_SCHED_MC
6412 for_each_cpu_mask(i
, *cpu_map
) {
6413 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6415 init_sched_groups_power(i
, sd
);
6419 for_each_cpu_mask(i
, *cpu_map
) {
6420 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6422 init_sched_groups_power(i
, sd
);
6426 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6427 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6430 struct sched_group
*sg
;
6432 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6433 init_numa_sched_groups_power(sg
);
6437 /* Attach the domains */
6438 for_each_cpu_mask(i
, *cpu_map
) {
6439 struct sched_domain
*sd
;
6440 #ifdef CONFIG_SCHED_SMT
6441 sd
= &per_cpu(cpu_domains
, i
);
6442 #elif defined(CONFIG_SCHED_MC)
6443 sd
= &per_cpu(core_domains
, i
);
6445 sd
= &per_cpu(phys_domains
, i
);
6447 cpu_attach_domain(sd
, i
);
6454 free_sched_groups(cpu_map
);
6459 static cpumask_t
*doms_cur
; /* current sched domains */
6460 static int ndoms_cur
; /* number of sched domains in 'doms_cur' */
6463 * Special case: If a kmalloc of a doms_cur partition (array of
6464 * cpumask_t) fails, then fallback to a single sched domain,
6465 * as determined by the single cpumask_t fallback_doms.
6467 static cpumask_t fallback_doms
;
6470 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6471 * For now this just excludes isolated cpus, but could be used to
6472 * exclude other special cases in the future.
6474 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6479 doms_cur
= kmalloc(sizeof(cpumask_t
), GFP_KERNEL
);
6481 doms_cur
= &fallback_doms
;
6482 cpus_andnot(*doms_cur
, *cpu_map
, cpu_isolated_map
);
6483 err
= build_sched_domains(doms_cur
);
6484 register_sched_domain_sysctl();
6489 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6491 free_sched_groups(cpu_map
);
6495 * Detach sched domains from a group of cpus specified in cpu_map
6496 * These cpus will now be attached to the NULL domain
6498 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6502 unregister_sched_domain_sysctl();
6504 for_each_cpu_mask(i
, *cpu_map
)
6505 cpu_attach_domain(NULL
, i
);
6506 synchronize_sched();
6507 arch_destroy_sched_domains(cpu_map
);
6511 * Partition sched domains as specified by the 'ndoms_new'
6512 * cpumasks in the array doms_new[] of cpumasks. This compares
6513 * doms_new[] to the current sched domain partitioning, doms_cur[].
6514 * It destroys each deleted domain and builds each new domain.
6516 * 'doms_new' is an array of cpumask_t's of length 'ndoms_new'.
6517 * The masks don't intersect (don't overlap.) We should setup one
6518 * sched domain for each mask. CPUs not in any of the cpumasks will
6519 * not be load balanced. If the same cpumask appears both in the
6520 * current 'doms_cur' domains and in the new 'doms_new', we can leave
6523 * The passed in 'doms_new' should be kmalloc'd. This routine takes
6524 * ownership of it and will kfree it when done with it. If the caller
6525 * failed the kmalloc call, then it can pass in doms_new == NULL,
6526 * and partition_sched_domains() will fallback to the single partition
6529 * Call with hotplug lock held
6531 void partition_sched_domains(int ndoms_new
, cpumask_t
*doms_new
)
6535 /* always unregister in case we don't destroy any domains */
6536 unregister_sched_domain_sysctl();
6538 if (doms_new
== NULL
) {
6540 doms_new
= &fallback_doms
;
6541 cpus_andnot(doms_new
[0], cpu_online_map
, cpu_isolated_map
);
6544 /* Destroy deleted domains */
6545 for (i
= 0; i
< ndoms_cur
; i
++) {
6546 for (j
= 0; j
< ndoms_new
; j
++) {
6547 if (cpus_equal(doms_cur
[i
], doms_new
[j
]))
6550 /* no match - a current sched domain not in new doms_new[] */
6551 detach_destroy_domains(doms_cur
+ i
);
6556 /* Build new domains */
6557 for (i
= 0; i
< ndoms_new
; i
++) {
6558 for (j
= 0; j
< ndoms_cur
; j
++) {
6559 if (cpus_equal(doms_new
[i
], doms_cur
[j
]))
6562 /* no match - add a new doms_new */
6563 build_sched_domains(doms_new
+ i
);
6568 /* Remember the new sched domains */
6569 if (doms_cur
!= &fallback_doms
)
6571 doms_cur
= doms_new
;
6572 ndoms_cur
= ndoms_new
;
6574 register_sched_domain_sysctl();
6577 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6578 static int arch_reinit_sched_domains(void)
6582 mutex_lock(&sched_hotcpu_mutex
);
6583 detach_destroy_domains(&cpu_online_map
);
6584 err
= arch_init_sched_domains(&cpu_online_map
);
6585 mutex_unlock(&sched_hotcpu_mutex
);
6590 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6594 if (buf
[0] != '0' && buf
[0] != '1')
6598 sched_smt_power_savings
= (buf
[0] == '1');
6600 sched_mc_power_savings
= (buf
[0] == '1');
6602 ret
= arch_reinit_sched_domains();
6604 return ret
? ret
: count
;
6607 #ifdef CONFIG_SCHED_MC
6608 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6610 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6612 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6613 const char *buf
, size_t count
)
6615 return sched_power_savings_store(buf
, count
, 0);
6617 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6618 sched_mc_power_savings_store
);
6621 #ifdef CONFIG_SCHED_SMT
6622 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6624 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6626 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6627 const char *buf
, size_t count
)
6629 return sched_power_savings_store(buf
, count
, 1);
6631 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6632 sched_smt_power_savings_store
);
6635 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6639 #ifdef CONFIG_SCHED_SMT
6641 err
= sysfs_create_file(&cls
->kset
.kobj
,
6642 &attr_sched_smt_power_savings
.attr
);
6644 #ifdef CONFIG_SCHED_MC
6645 if (!err
&& mc_capable())
6646 err
= sysfs_create_file(&cls
->kset
.kobj
,
6647 &attr_sched_mc_power_savings
.attr
);
6654 * Force a reinitialization of the sched domains hierarchy. The domains
6655 * and groups cannot be updated in place without racing with the balancing
6656 * code, so we temporarily attach all running cpus to the NULL domain
6657 * which will prevent rebalancing while the sched domains are recalculated.
6659 static int update_sched_domains(struct notifier_block
*nfb
,
6660 unsigned long action
, void *hcpu
)
6663 case CPU_UP_PREPARE
:
6664 case CPU_UP_PREPARE_FROZEN
:
6665 case CPU_DOWN_PREPARE
:
6666 case CPU_DOWN_PREPARE_FROZEN
:
6667 detach_destroy_domains(&cpu_online_map
);
6670 case CPU_UP_CANCELED
:
6671 case CPU_UP_CANCELED_FROZEN
:
6672 case CPU_DOWN_FAILED
:
6673 case CPU_DOWN_FAILED_FROZEN
:
6675 case CPU_ONLINE_FROZEN
:
6677 case CPU_DEAD_FROZEN
:
6679 * Fall through and re-initialise the domains.
6686 /* The hotplug lock is already held by cpu_up/cpu_down */
6687 arch_init_sched_domains(&cpu_online_map
);
6692 void __init
sched_init_smp(void)
6694 cpumask_t non_isolated_cpus
;
6696 mutex_lock(&sched_hotcpu_mutex
);
6697 arch_init_sched_domains(&cpu_online_map
);
6698 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6699 if (cpus_empty(non_isolated_cpus
))
6700 cpu_set(smp_processor_id(), non_isolated_cpus
);
6701 mutex_unlock(&sched_hotcpu_mutex
);
6702 /* XXX: Theoretical race here - CPU may be hotplugged now */
6703 hotcpu_notifier(update_sched_domains
, 0);
6705 /* Move init over to a non-isolated CPU */
6706 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6708 sched_init_granularity();
6711 void __init
sched_init_smp(void)
6713 sched_init_granularity();
6715 #endif /* CONFIG_SMP */
6717 int in_sched_functions(unsigned long addr
)
6719 /* Linker adds these: start and end of __sched functions */
6720 extern char __sched_text_start
[], __sched_text_end
[];
6722 return in_lock_functions(addr
) ||
6723 (addr
>= (unsigned long)__sched_text_start
6724 && addr
< (unsigned long)__sched_text_end
);
6727 static void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
6729 cfs_rq
->tasks_timeline
= RB_ROOT
;
6730 #ifdef CONFIG_FAIR_GROUP_SCHED
6733 cfs_rq
->min_vruntime
= (u64
)(-(1LL << 20));
6736 void __init
sched_init(void)
6738 int highest_cpu
= 0;
6741 for_each_possible_cpu(i
) {
6742 struct rt_prio_array
*array
;
6746 spin_lock_init(&rq
->lock
);
6747 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6750 init_cfs_rq(&rq
->cfs
, rq
);
6751 #ifdef CONFIG_FAIR_GROUP_SCHED
6752 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6754 struct cfs_rq
*cfs_rq
= &per_cpu(init_cfs_rq
, i
);
6755 struct sched_entity
*se
=
6756 &per_cpu(init_sched_entity
, i
);
6758 init_cfs_rq_p
[i
] = cfs_rq
;
6759 init_cfs_rq(cfs_rq
, rq
);
6760 cfs_rq
->tg
= &init_task_group
;
6761 list_add(&cfs_rq
->leaf_cfs_rq_list
,
6762 &rq
->leaf_cfs_rq_list
);
6764 init_sched_entity_p
[i
] = se
;
6765 se
->cfs_rq
= &rq
->cfs
;
6767 se
->load
.weight
= init_task_group_load
;
6768 se
->load
.inv_weight
=
6769 div64_64(1ULL<<32, init_task_group_load
);
6772 init_task_group
.shares
= init_task_group_load
;
6773 spin_lock_init(&init_task_group
.lock
);
6776 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6777 rq
->cpu_load
[j
] = 0;
6780 rq
->active_balance
= 0;
6781 rq
->next_balance
= jiffies
;
6784 rq
->migration_thread
= NULL
;
6785 INIT_LIST_HEAD(&rq
->migration_queue
);
6787 atomic_set(&rq
->nr_iowait
, 0);
6789 array
= &rq
->rt
.active
;
6790 for (j
= 0; j
< MAX_RT_PRIO
; j
++) {
6791 INIT_LIST_HEAD(array
->queue
+ j
);
6792 __clear_bit(j
, array
->bitmap
);
6795 /* delimiter for bitsearch: */
6796 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
6799 set_load_weight(&init_task
);
6801 #ifdef CONFIG_PREEMPT_NOTIFIERS
6802 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6806 nr_cpu_ids
= highest_cpu
+ 1;
6807 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6810 #ifdef CONFIG_RT_MUTEXES
6811 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6815 * The boot idle thread does lazy MMU switching as well:
6817 atomic_inc(&init_mm
.mm_count
);
6818 enter_lazy_tlb(&init_mm
, current
);
6821 * Make us the idle thread. Technically, schedule() should not be
6822 * called from this thread, however somewhere below it might be,
6823 * but because we are the idle thread, we just pick up running again
6824 * when this runqueue becomes "idle".
6826 init_idle(current
, smp_processor_id());
6828 * During early bootup we pretend to be a normal task:
6830 current
->sched_class
= &fair_sched_class
;
6833 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6834 void __might_sleep(char *file
, int line
)
6837 static unsigned long prev_jiffy
; /* ratelimiting */
6839 if ((in_atomic() || irqs_disabled()) &&
6840 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6841 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6843 prev_jiffy
= jiffies
;
6844 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6845 " context at %s:%d\n", file
, line
);
6846 printk("in_atomic():%d, irqs_disabled():%d\n",
6847 in_atomic(), irqs_disabled());
6848 debug_show_held_locks(current
);
6849 if (irqs_disabled())
6850 print_irqtrace_events(current
);
6855 EXPORT_SYMBOL(__might_sleep
);
6858 #ifdef CONFIG_MAGIC_SYSRQ
6859 static void normalize_task(struct rq
*rq
, struct task_struct
*p
)
6862 update_rq_clock(rq
);
6863 on_rq
= p
->se
.on_rq
;
6865 deactivate_task(rq
, p
, 0);
6866 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
6868 activate_task(rq
, p
, 0);
6869 resched_task(rq
->curr
);
6873 void normalize_rt_tasks(void)
6875 struct task_struct
*g
, *p
;
6876 unsigned long flags
;
6879 read_lock_irq(&tasklist_lock
);
6880 do_each_thread(g
, p
) {
6882 * Only normalize user tasks:
6887 p
->se
.exec_start
= 0;
6888 #ifdef CONFIG_SCHEDSTATS
6889 p
->se
.wait_start
= 0;
6890 p
->se
.sleep_start
= 0;
6891 p
->se
.block_start
= 0;
6893 task_rq(p
)->clock
= 0;
6897 * Renice negative nice level userspace
6900 if (TASK_NICE(p
) < 0 && p
->mm
)
6901 set_user_nice(p
, 0);
6905 spin_lock_irqsave(&p
->pi_lock
, flags
);
6906 rq
= __task_rq_lock(p
);
6908 normalize_task(rq
, p
);
6910 __task_rq_unlock(rq
);
6911 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
6912 } while_each_thread(g
, p
);
6914 read_unlock_irq(&tasklist_lock
);
6917 #endif /* CONFIG_MAGIC_SYSRQ */
6921 * These functions are only useful for the IA64 MCA handling.
6923 * They can only be called when the whole system has been
6924 * stopped - every CPU needs to be quiescent, and no scheduling
6925 * activity can take place. Using them for anything else would
6926 * be a serious bug, and as a result, they aren't even visible
6927 * under any other configuration.
6931 * curr_task - return the current task for a given cpu.
6932 * @cpu: the processor in question.
6934 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6936 struct task_struct
*curr_task(int cpu
)
6938 return cpu_curr(cpu
);
6942 * set_curr_task - set the current task for a given cpu.
6943 * @cpu: the processor in question.
6944 * @p: the task pointer to set.
6946 * Description: This function must only be used when non-maskable interrupts
6947 * are serviced on a separate stack. It allows the architecture to switch the
6948 * notion of the current task on a cpu in a non-blocking manner. This function
6949 * must be called with all CPU's synchronized, and interrupts disabled, the
6950 * and caller must save the original value of the current task (see
6951 * curr_task() above) and restore that value before reenabling interrupts and
6952 * re-starting the system.
6954 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6956 void set_curr_task(int cpu
, struct task_struct
*p
)
6963 #ifdef CONFIG_FAIR_GROUP_SCHED
6965 /* allocate runqueue etc for a new task group */
6966 struct task_group
*sched_create_group(void)
6968 struct task_group
*tg
;
6969 struct cfs_rq
*cfs_rq
;
6970 struct sched_entity
*se
;
6974 tg
= kzalloc(sizeof(*tg
), GFP_KERNEL
);
6976 return ERR_PTR(-ENOMEM
);
6978 tg
->cfs_rq
= kzalloc(sizeof(cfs_rq
) * NR_CPUS
, GFP_KERNEL
);
6981 tg
->se
= kzalloc(sizeof(se
) * NR_CPUS
, GFP_KERNEL
);
6985 for_each_possible_cpu(i
) {
6988 cfs_rq
= kmalloc_node(sizeof(struct cfs_rq
), GFP_KERNEL
,
6993 se
= kmalloc_node(sizeof(struct sched_entity
), GFP_KERNEL
,
6998 memset(cfs_rq
, 0, sizeof(struct cfs_rq
));
6999 memset(se
, 0, sizeof(struct sched_entity
));
7001 tg
->cfs_rq
[i
] = cfs_rq
;
7002 init_cfs_rq(cfs_rq
, rq
);
7006 se
->cfs_rq
= &rq
->cfs
;
7008 se
->load
.weight
= NICE_0_LOAD
;
7009 se
->load
.inv_weight
= div64_64(1ULL<<32, NICE_0_LOAD
);
7013 for_each_possible_cpu(i
) {
7015 cfs_rq
= tg
->cfs_rq
[i
];
7016 list_add_rcu(&cfs_rq
->leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
7019 tg
->shares
= NICE_0_LOAD
;
7020 spin_lock_init(&tg
->lock
);
7025 for_each_possible_cpu(i
) {
7027 kfree(tg
->cfs_rq
[i
]);
7035 return ERR_PTR(-ENOMEM
);
7038 /* rcu callback to free various structures associated with a task group */
7039 static void free_sched_group(struct rcu_head
*rhp
)
7041 struct task_group
*tg
= container_of(rhp
, struct task_group
, rcu
);
7042 struct cfs_rq
*cfs_rq
;
7043 struct sched_entity
*se
;
7046 /* now it should be safe to free those cfs_rqs */
7047 for_each_possible_cpu(i
) {
7048 cfs_rq
= tg
->cfs_rq
[i
];
7060 /* Destroy runqueue etc associated with a task group */
7061 void sched_destroy_group(struct task_group
*tg
)
7063 struct cfs_rq
*cfs_rq
= NULL
;
7066 for_each_possible_cpu(i
) {
7067 cfs_rq
= tg
->cfs_rq
[i
];
7068 list_del_rcu(&cfs_rq
->leaf_cfs_rq_list
);
7073 /* wait for possible concurrent references to cfs_rqs complete */
7074 call_rcu(&tg
->rcu
, free_sched_group
);
7077 /* change task's runqueue when it moves between groups.
7078 * The caller of this function should have put the task in its new group
7079 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to
7080 * reflect its new group.
7082 void sched_move_task(struct task_struct
*tsk
)
7085 unsigned long flags
;
7088 rq
= task_rq_lock(tsk
, &flags
);
7090 if (tsk
->sched_class
!= &fair_sched_class
)
7093 update_rq_clock(rq
);
7095 running
= task_running(rq
, tsk
);
7096 on_rq
= tsk
->se
.on_rq
;
7099 dequeue_task(rq
, tsk
, 0);
7100 if (unlikely(running
))
7101 tsk
->sched_class
->put_prev_task(rq
, tsk
);
7104 set_task_cfs_rq(tsk
);
7107 if (unlikely(running
))
7108 tsk
->sched_class
->set_curr_task(rq
);
7109 enqueue_task(rq
, tsk
, 0);
7113 task_rq_unlock(rq
, &flags
);
7116 static void set_se_shares(struct sched_entity
*se
, unsigned long shares
)
7118 struct cfs_rq
*cfs_rq
= se
->cfs_rq
;
7119 struct rq
*rq
= cfs_rq
->rq
;
7122 spin_lock_irq(&rq
->lock
);
7126 dequeue_entity(cfs_rq
, se
, 0);
7128 se
->load
.weight
= shares
;
7129 se
->load
.inv_weight
= div64_64((1ULL<<32), shares
);
7132 enqueue_entity(cfs_rq
, se
, 0);
7134 spin_unlock_irq(&rq
->lock
);
7137 int sched_group_set_shares(struct task_group
*tg
, unsigned long shares
)
7141 spin_lock(&tg
->lock
);
7142 if (tg
->shares
== shares
)
7145 tg
->shares
= shares
;
7146 for_each_possible_cpu(i
)
7147 set_se_shares(tg
->se
[i
], shares
);
7150 spin_unlock(&tg
->lock
);
7154 unsigned long sched_group_shares(struct task_group
*tg
)
7159 #endif /* CONFIG_FAIR_GROUP_SCHED */
7161 #ifdef CONFIG_FAIR_CGROUP_SCHED
7163 /* return corresponding task_group object of a cgroup */
7164 static inline struct task_group
*cgroup_tg(struct cgroup
*cgrp
)
7166 return container_of(cgroup_subsys_state(cgrp
, cpu_cgroup_subsys_id
),
7167 struct task_group
, css
);
7170 static struct cgroup_subsys_state
*
7171 cpu_cgroup_create(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
7173 struct task_group
*tg
;
7175 if (!cgrp
->parent
) {
7176 /* This is early initialization for the top cgroup */
7177 init_task_group
.css
.cgroup
= cgrp
;
7178 return &init_task_group
.css
;
7181 /* we support only 1-level deep hierarchical scheduler atm */
7182 if (cgrp
->parent
->parent
)
7183 return ERR_PTR(-EINVAL
);
7185 tg
= sched_create_group();
7187 return ERR_PTR(-ENOMEM
);
7189 /* Bind the cgroup to task_group object we just created */
7190 tg
->css
.cgroup
= cgrp
;
7195 static void cpu_cgroup_destroy(struct cgroup_subsys
*ss
,
7196 struct cgroup
*cgrp
)
7198 struct task_group
*tg
= cgroup_tg(cgrp
);
7200 sched_destroy_group(tg
);
7203 static int cpu_cgroup_can_attach(struct cgroup_subsys
*ss
,
7204 struct cgroup
*cgrp
, struct task_struct
*tsk
)
7206 /* We don't support RT-tasks being in separate groups */
7207 if (tsk
->sched_class
!= &fair_sched_class
)
7214 cpu_cgroup_attach(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
7215 struct cgroup
*old_cont
, struct task_struct
*tsk
)
7217 sched_move_task(tsk
);
7220 static int cpu_shares_write_uint(struct cgroup
*cgrp
, struct cftype
*cftype
,
7223 return sched_group_set_shares(cgroup_tg(cgrp
), shareval
);
7226 static u64
cpu_shares_read_uint(struct cgroup
*cgrp
, struct cftype
*cft
)
7228 struct task_group
*tg
= cgroup_tg(cgrp
);
7230 return (u64
) tg
->shares
;
7233 static u64
cpu_usage_read(struct cgroup
*cgrp
, struct cftype
*cft
)
7235 struct task_group
*tg
= cgroup_tg(cgrp
);
7236 unsigned long flags
;
7240 for_each_possible_cpu(i
) {
7242 * Lock to prevent races with updating 64-bit counters
7245 spin_lock_irqsave(&cpu_rq(i
)->lock
, flags
);
7246 res
+= tg
->se
[i
]->sum_exec_runtime
;
7247 spin_unlock_irqrestore(&cpu_rq(i
)->lock
, flags
);
7249 /* Convert from ns to ms */
7250 do_div(res
, NSEC_PER_MSEC
);
7255 static struct cftype cpu_files
[] = {
7258 .read_uint
= cpu_shares_read_uint
,
7259 .write_uint
= cpu_shares_write_uint
,
7263 .read_uint
= cpu_usage_read
,
7267 static int cpu_cgroup_populate(struct cgroup_subsys
*ss
, struct cgroup
*cont
)
7269 return cgroup_add_files(cont
, ss
, cpu_files
, ARRAY_SIZE(cpu_files
));
7272 struct cgroup_subsys cpu_cgroup_subsys
= {
7274 .create
= cpu_cgroup_create
,
7275 .destroy
= cpu_cgroup_destroy
,
7276 .can_attach
= cpu_cgroup_can_attach
,
7277 .attach
= cpu_cgroup_attach
,
7278 .populate
= cpu_cgroup_populate
,
7279 .subsys_id
= cpu_cgroup_subsys_id
,
7283 #endif /* CONFIG_FAIR_CGROUP_SCHED */