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/smp.h>
48 #include <linux/threads.h>
49 #include <linux/timer.h>
50 #include <linux/rcupdate.h>
51 #include <linux/cpu.h>
52 #include <linux/cpuset.h>
53 #include <linux/percpu.h>
54 #include <linux/kthread.h>
55 #include <linux/seq_file.h>
56 #include <linux/sysctl.h>
57 #include <linux/syscalls.h>
58 #include <linux/times.h>
59 #include <linux/tsacct_kern.h>
60 #include <linux/kprobes.h>
61 #include <linux/delayacct.h>
62 #include <linux/reciprocal_div.h>
63 #include <linux/unistd.h>
64 #include <linux/pagemap.h>
69 * Scheduler clock - returns current time in nanosec units.
70 * This is default implementation.
71 * Architectures and sub-architectures can override this.
73 unsigned long long __attribute__((weak
)) sched_clock(void)
75 return (unsigned long long)jiffies
* (1000000000 / HZ
);
79 * Convert user-nice values [ -20 ... 0 ... 19 ]
80 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
83 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
84 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
85 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
88 * 'User priority' is the nice value converted to something we
89 * can work with better when scaling various scheduler parameters,
90 * it's a [ 0 ... 39 ] range.
92 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
93 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
94 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
97 * Some helpers for converting nanosecond timing to jiffy resolution
99 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
100 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
102 #define NICE_0_LOAD SCHED_LOAD_SCALE
103 #define NICE_0_SHIFT SCHED_LOAD_SHIFT
106 * These are the 'tuning knobs' of the scheduler:
108 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
109 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
110 * Timeslices get refilled after they expire.
112 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
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 #define SCALE_PRIO(x, prio) \
137 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
140 * static_prio_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
141 * to time slice values: [800ms ... 100ms ... 5ms]
143 static unsigned int static_prio_timeslice(int static_prio
)
145 if (static_prio
== NICE_TO_PRIO(19))
148 if (static_prio
< NICE_TO_PRIO(0))
149 return SCALE_PRIO(DEF_TIMESLICE
* 4, static_prio
);
151 return SCALE_PRIO(DEF_TIMESLICE
, static_prio
);
154 static inline int rt_policy(int policy
)
156 if (unlikely(policy
== SCHED_FIFO
) || unlikely(policy
== SCHED_RR
))
161 static inline int task_has_rt_policy(struct task_struct
*p
)
163 return rt_policy(p
->policy
);
167 * This is the priority-queue data structure of the RT scheduling class:
169 struct rt_prio_array
{
170 DECLARE_BITMAP(bitmap
, MAX_RT_PRIO
+1); /* include 1 bit for delimiter */
171 struct list_head queue
[MAX_RT_PRIO
];
175 struct load_weight load
;
178 /* CFS-related fields in a runqueue */
180 struct load_weight load
;
181 unsigned long nr_running
;
187 unsigned long wait_runtime_overruns
, wait_runtime_underruns
;
189 struct rb_root tasks_timeline
;
190 struct rb_node
*rb_leftmost
;
191 struct rb_node
*rb_load_balance_curr
;
192 #ifdef CONFIG_FAIR_GROUP_SCHED
193 /* 'curr' points to currently running entity on this cfs_rq.
194 * It is set to NULL otherwise (i.e when none are currently running).
196 struct sched_entity
*curr
;
197 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
199 /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
200 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
201 * (like users, containers etc.)
203 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
204 * list is used during load balance.
206 struct list_head leaf_cfs_rq_list
; /* Better name : task_cfs_rq_list? */
210 /* Real-Time classes' related field in a runqueue: */
212 struct rt_prio_array active
;
213 int rt_load_balance_idx
;
214 struct list_head
*rt_load_balance_head
, *rt_load_balance_curr
;
218 * This is the main, per-CPU runqueue data structure.
220 * Locking rule: those places that want to lock multiple runqueues
221 * (such as the load balancing or the thread migration code), lock
222 * acquire operations must be ordered by ascending &runqueue.
225 spinlock_t lock
; /* runqueue lock */
228 * nr_running and cpu_load should be in the same cacheline because
229 * remote CPUs use both these fields when doing load calculation.
231 unsigned long nr_running
;
232 #define CPU_LOAD_IDX_MAX 5
233 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
234 unsigned char idle_at_tick
;
236 unsigned char in_nohz_recently
;
238 struct load_stat ls
; /* capture load from *all* tasks on this cpu */
239 unsigned long nr_load_updates
;
243 #ifdef CONFIG_FAIR_GROUP_SCHED
244 struct list_head leaf_cfs_rq_list
; /* list of leaf cfs_rq on this cpu */
249 * This is part of a global counter where only the total sum
250 * over all CPUs matters. A task can increase this counter on
251 * one CPU and if it got migrated afterwards it may decrease
252 * it on another CPU. Always updated under the runqueue lock:
254 unsigned long nr_uninterruptible
;
256 struct task_struct
*curr
, *idle
;
257 unsigned long next_balance
;
258 struct mm_struct
*prev_mm
;
260 u64 clock
, prev_clock_raw
;
263 unsigned int clock_warps
, clock_overflows
;
265 unsigned int clock_deep_idle_events
;
271 struct sched_domain
*sd
;
273 /* For active balancing */
276 int cpu
; /* cpu of this runqueue */
278 struct task_struct
*migration_thread
;
279 struct list_head migration_queue
;
282 #ifdef CONFIG_SCHEDSTATS
284 struct sched_info rq_sched_info
;
286 /* sys_sched_yield() stats */
287 unsigned long yld_exp_empty
;
288 unsigned long yld_act_empty
;
289 unsigned long yld_both_empty
;
290 unsigned long yld_cnt
;
292 /* schedule() stats */
293 unsigned long sched_switch
;
294 unsigned long sched_cnt
;
295 unsigned long sched_goidle
;
297 /* try_to_wake_up() stats */
298 unsigned long ttwu_cnt
;
299 unsigned long ttwu_local
;
301 struct lock_class_key rq_lock_key
;
304 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
305 static DEFINE_MUTEX(sched_hotcpu_mutex
);
307 static inline void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
)
309 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
);
312 static inline int cpu_of(struct rq
*rq
)
322 * Update the per-runqueue clock, as finegrained as the platform can give
323 * us, but without assuming monotonicity, etc.:
325 static void __update_rq_clock(struct rq
*rq
)
327 u64 prev_raw
= rq
->prev_clock_raw
;
328 u64 now
= sched_clock();
329 s64 delta
= now
- prev_raw
;
330 u64 clock
= rq
->clock
;
332 #ifdef CONFIG_SCHED_DEBUG
333 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
336 * Protect against sched_clock() occasionally going backwards:
338 if (unlikely(delta
< 0)) {
343 * Catch too large forward jumps too:
345 if (unlikely(clock
+ delta
> rq
->tick_timestamp
+ TICK_NSEC
)) {
346 if (clock
< rq
->tick_timestamp
+ TICK_NSEC
)
347 clock
= rq
->tick_timestamp
+ TICK_NSEC
;
350 rq
->clock_overflows
++;
352 if (unlikely(delta
> rq
->clock_max_delta
))
353 rq
->clock_max_delta
= delta
;
358 rq
->prev_clock_raw
= now
;
362 static void update_rq_clock(struct rq
*rq
)
364 if (likely(smp_processor_id() == cpu_of(rq
)))
365 __update_rq_clock(rq
);
369 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
370 * See detach_destroy_domains: synchronize_sched for details.
372 * The domain tree of any CPU may only be accessed from within
373 * preempt-disabled sections.
375 #define for_each_domain(cpu, __sd) \
376 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
378 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
379 #define this_rq() (&__get_cpu_var(runqueues))
380 #define task_rq(p) cpu_rq(task_cpu(p))
381 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
384 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
385 * clock constructed from sched_clock():
387 unsigned long long cpu_clock(int cpu
)
389 unsigned long long now
;
393 local_irq_save(flags
);
397 local_irq_restore(flags
);
402 #ifdef CONFIG_FAIR_GROUP_SCHED
403 /* Change a task's ->cfs_rq if it moves across CPUs */
404 static inline void set_task_cfs_rq(struct task_struct
*p
)
406 p
->se
.cfs_rq
= &task_rq(p
)->cfs
;
409 static inline void set_task_cfs_rq(struct task_struct
*p
)
414 #ifndef prepare_arch_switch
415 # define prepare_arch_switch(next) do { } while (0)
417 #ifndef finish_arch_switch
418 # define finish_arch_switch(prev) do { } while (0)
421 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
422 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
424 return rq
->curr
== p
;
427 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
431 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
433 #ifdef CONFIG_DEBUG_SPINLOCK
434 /* this is a valid case when another task releases the spinlock */
435 rq
->lock
.owner
= current
;
438 * If we are tracking spinlock dependencies then we have to
439 * fix up the runqueue lock - which gets 'carried over' from
442 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
444 spin_unlock_irq(&rq
->lock
);
447 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
448 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
453 return rq
->curr
== p
;
457 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
461 * We can optimise this out completely for !SMP, because the
462 * SMP rebalancing from interrupt is the only thing that cares
467 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
468 spin_unlock_irq(&rq
->lock
);
470 spin_unlock(&rq
->lock
);
474 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
478 * After ->oncpu is cleared, the task can be moved to a different CPU.
479 * We must ensure this doesn't happen until the switch is completely
485 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
489 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
492 * __task_rq_lock - lock the runqueue a given task resides on.
493 * Must be called interrupts disabled.
495 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
502 spin_lock(&rq
->lock
);
503 if (unlikely(rq
!= task_rq(p
))) {
504 spin_unlock(&rq
->lock
);
505 goto repeat_lock_task
;
511 * task_rq_lock - lock the runqueue a given task resides on and disable
512 * interrupts. Note the ordering: we can safely lookup the task_rq without
513 * explicitly disabling preemption.
515 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
521 local_irq_save(*flags
);
523 spin_lock(&rq
->lock
);
524 if (unlikely(rq
!= task_rq(p
))) {
525 spin_unlock_irqrestore(&rq
->lock
, *flags
);
526 goto repeat_lock_task
;
531 static inline void __task_rq_unlock(struct rq
*rq
)
534 spin_unlock(&rq
->lock
);
537 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
540 spin_unlock_irqrestore(&rq
->lock
, *flags
);
544 * this_rq_lock - lock this runqueue and disable interrupts.
546 static inline struct rq
*this_rq_lock(void)
553 spin_lock(&rq
->lock
);
559 * We are going deep-idle (irqs are disabled):
561 void sched_clock_idle_sleep_event(void)
563 struct rq
*rq
= cpu_rq(smp_processor_id());
565 spin_lock(&rq
->lock
);
566 __update_rq_clock(rq
);
567 spin_unlock(&rq
->lock
);
568 rq
->clock_deep_idle_events
++;
570 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
573 * We just idled delta nanoseconds (called with irqs disabled):
575 void sched_clock_idle_wakeup_event(u64 delta_ns
)
577 struct rq
*rq
= cpu_rq(smp_processor_id());
578 u64 now
= sched_clock();
580 rq
->idle_clock
+= delta_ns
;
582 * Override the previous timestamp and ignore all
583 * sched_clock() deltas that occured while we idled,
584 * and use the PM-provided delta_ns to advance the
587 spin_lock(&rq
->lock
);
588 rq
->prev_clock_raw
= now
;
589 rq
->clock
+= delta_ns
;
590 spin_unlock(&rq
->lock
);
592 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
595 * resched_task - mark a task 'to be rescheduled now'.
597 * On UP this means the setting of the need_resched flag, on SMP it
598 * might also involve a cross-CPU call to trigger the scheduler on
603 #ifndef tsk_is_polling
604 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
607 static void resched_task(struct task_struct
*p
)
611 assert_spin_locked(&task_rq(p
)->lock
);
613 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
616 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
619 if (cpu
== smp_processor_id())
622 /* NEED_RESCHED must be visible before we test polling */
624 if (!tsk_is_polling(p
))
625 smp_send_reschedule(cpu
);
628 static void resched_cpu(int cpu
)
630 struct rq
*rq
= cpu_rq(cpu
);
633 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
635 resched_task(cpu_curr(cpu
));
636 spin_unlock_irqrestore(&rq
->lock
, flags
);
639 static inline void resched_task(struct task_struct
*p
)
641 assert_spin_locked(&task_rq(p
)->lock
);
642 set_tsk_need_resched(p
);
646 static u64
div64_likely32(u64 divident
, unsigned long divisor
)
648 #if BITS_PER_LONG == 32
649 if (likely(divident
<= 0xffffffffULL
))
650 return (u32
)divident
/ divisor
;
651 do_div(divident
, divisor
);
655 return divident
/ divisor
;
659 #if BITS_PER_LONG == 32
660 # define WMULT_CONST (~0UL)
662 # define WMULT_CONST (1UL << 32)
665 #define WMULT_SHIFT 32
668 * Shift right and round:
670 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
673 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
674 struct load_weight
*lw
)
678 if (unlikely(!lw
->inv_weight
))
679 lw
->inv_weight
= (WMULT_CONST
- lw
->weight
/2) / lw
->weight
+ 1;
681 tmp
= (u64
)delta_exec
* weight
;
683 * Check whether we'd overflow the 64-bit multiplication:
685 if (unlikely(tmp
> WMULT_CONST
))
686 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
689 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
691 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
694 static inline unsigned long
695 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
697 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
700 static void update_load_add(struct load_weight
*lw
, unsigned long inc
)
706 static void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
713 * To aid in avoiding the subversion of "niceness" due to uneven distribution
714 * of tasks with abnormal "nice" values across CPUs the contribution that
715 * each task makes to its run queue's load is weighted according to its
716 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
717 * scaled version of the new time slice allocation that they receive on time
721 #define WEIGHT_IDLEPRIO 2
722 #define WMULT_IDLEPRIO (1 << 31)
725 * Nice levels are multiplicative, with a gentle 10% change for every
726 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
727 * nice 1, it will get ~10% less CPU time than another CPU-bound task
728 * that remained on nice 0.
730 * The "10% effect" is relative and cumulative: from _any_ nice level,
731 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
732 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
733 * If a task goes up by ~10% and another task goes down by ~10% then
734 * the relative distance between them is ~25%.)
736 static const int prio_to_weight
[40] = {
737 /* -20 */ 88761, 71755, 56483, 46273, 36291,
738 /* -15 */ 29154, 23254, 18705, 14949, 11916,
739 /* -10 */ 9548, 7620, 6100, 4904, 3906,
740 /* -5 */ 3121, 2501, 1991, 1586, 1277,
741 /* 0 */ 1024, 820, 655, 526, 423,
742 /* 5 */ 335, 272, 215, 172, 137,
743 /* 10 */ 110, 87, 70, 56, 45,
744 /* 15 */ 36, 29, 23, 18, 15,
748 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
750 * In cases where the weight does not change often, we can use the
751 * precalculated inverse to speed up arithmetics by turning divisions
752 * into multiplications:
754 static const u32 prio_to_wmult
[40] = {
755 /* -20 */ 48388, 59856, 76040, 92818, 118348,
756 /* -15 */ 147320, 184698, 229616, 287308, 360437,
757 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
758 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
759 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
760 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
761 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
762 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
765 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
768 * runqueue iterator, to support SMP load-balancing between different
769 * scheduling classes, without having to expose their internal data
770 * structures to the load-balancing proper:
774 struct task_struct
*(*start
)(void *);
775 struct task_struct
*(*next
)(void *);
778 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
779 unsigned long max_nr_move
, unsigned long max_load_move
,
780 struct sched_domain
*sd
, enum cpu_idle_type idle
,
781 int *all_pinned
, unsigned long *load_moved
,
782 int *this_best_prio
, struct rq_iterator
*iterator
);
784 #include "sched_stats.h"
785 #include "sched_rt.c"
786 #include "sched_fair.c"
787 #include "sched_idletask.c"
788 #ifdef CONFIG_SCHED_DEBUG
789 # include "sched_debug.c"
792 #define sched_class_highest (&rt_sched_class)
795 * Update delta_exec, delta_fair fields for rq.
797 * delta_fair clock advances at a rate inversely proportional to
798 * total load (rq->ls.load.weight) on the runqueue, while
799 * delta_exec advances at the same rate as wall-clock (provided
802 * delta_exec / delta_fair is a measure of the (smoothened) load on this
803 * runqueue over any given interval. This (smoothened) load is used
804 * during load balance.
806 * This function is called /before/ updating rq->ls.load
807 * and when switching tasks.
809 static inline void inc_load(struct rq
*rq
, const struct task_struct
*p
)
811 update_load_add(&rq
->ls
.load
, p
->se
.load
.weight
);
814 static inline void dec_load(struct rq
*rq
, const struct task_struct
*p
)
816 update_load_sub(&rq
->ls
.load
, p
->se
.load
.weight
);
819 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
825 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
831 static void set_load_weight(struct task_struct
*p
)
833 p
->se
.wait_runtime
= 0;
835 if (task_has_rt_policy(p
)) {
836 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
837 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
842 * SCHED_IDLE tasks get minimal weight:
844 if (p
->policy
== SCHED_IDLE
) {
845 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
846 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
850 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
851 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
854 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
856 sched_info_queued(p
);
857 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
861 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
863 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
868 * __normal_prio - return the priority that is based on the static prio
870 static inline int __normal_prio(struct task_struct
*p
)
872 return p
->static_prio
;
876 * Calculate the expected normal priority: i.e. priority
877 * without taking RT-inheritance into account. Might be
878 * boosted by interactivity modifiers. Changes upon fork,
879 * setprio syscalls, and whenever the interactivity
880 * estimator recalculates.
882 static inline int normal_prio(struct task_struct
*p
)
886 if (task_has_rt_policy(p
))
887 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
889 prio
= __normal_prio(p
);
894 * Calculate the current priority, i.e. the priority
895 * taken into account by the scheduler. This value might
896 * be boosted by RT tasks, or might be boosted by
897 * interactivity modifiers. Will be RT if the task got
898 * RT-boosted. If not then it returns p->normal_prio.
900 static int effective_prio(struct task_struct
*p
)
902 p
->normal_prio
= normal_prio(p
);
904 * If we are RT tasks or we were boosted to RT priority,
905 * keep the priority unchanged. Otherwise, update priority
906 * to the normal priority:
908 if (!rt_prio(p
->prio
))
909 return p
->normal_prio
;
914 * activate_task - move a task to the runqueue.
916 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
918 if (p
->state
== TASK_UNINTERRUPTIBLE
)
919 rq
->nr_uninterruptible
--;
921 enqueue_task(rq
, p
, wakeup
);
922 inc_nr_running(p
, rq
);
926 * activate_idle_task - move idle task to the _front_ of runqueue.
928 static inline void activate_idle_task(struct task_struct
*p
, struct rq
*rq
)
932 if (p
->state
== TASK_UNINTERRUPTIBLE
)
933 rq
->nr_uninterruptible
--;
935 enqueue_task(rq
, p
, 0);
936 inc_nr_running(p
, rq
);
940 * deactivate_task - remove a task from the runqueue.
942 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
944 if (p
->state
== TASK_UNINTERRUPTIBLE
)
945 rq
->nr_uninterruptible
++;
947 dequeue_task(rq
, p
, sleep
);
948 dec_nr_running(p
, rq
);
952 * task_curr - is this task currently executing on a CPU?
953 * @p: the task in question.
955 inline int task_curr(const struct task_struct
*p
)
957 return cpu_curr(task_cpu(p
)) == p
;
960 /* Used instead of source_load when we know the type == 0 */
961 unsigned long weighted_cpuload(const int cpu
)
963 return cpu_rq(cpu
)->ls
.load
.weight
;
966 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
969 task_thread_info(p
)->cpu
= cpu
;
976 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
978 int old_cpu
= task_cpu(p
);
979 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
980 u64 clock_offset
, fair_clock_offset
;
982 clock_offset
= old_rq
->clock
- new_rq
->clock
;
983 fair_clock_offset
= old_rq
->cfs
.fair_clock
- new_rq
->cfs
.fair_clock
;
985 if (p
->se
.wait_start_fair
)
986 p
->se
.wait_start_fair
-= fair_clock_offset
;
987 if (p
->se
.sleep_start_fair
)
988 p
->se
.sleep_start_fair
-= fair_clock_offset
;
990 #ifdef CONFIG_SCHEDSTATS
991 if (p
->se
.wait_start
)
992 p
->se
.wait_start
-= clock_offset
;
993 if (p
->se
.sleep_start
)
994 p
->se
.sleep_start
-= clock_offset
;
995 if (p
->se
.block_start
)
996 p
->se
.block_start
-= clock_offset
;
999 __set_task_cpu(p
, new_cpu
);
1002 struct migration_req
{
1003 struct list_head list
;
1005 struct task_struct
*task
;
1008 struct completion done
;
1012 * The task's runqueue lock must be held.
1013 * Returns true if you have to wait for migration thread.
1016 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1018 struct rq
*rq
= task_rq(p
);
1021 * If the task is not on a runqueue (and not running), then
1022 * it is sufficient to simply update the task's cpu field.
1024 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1025 set_task_cpu(p
, dest_cpu
);
1029 init_completion(&req
->done
);
1031 req
->dest_cpu
= dest_cpu
;
1032 list_add(&req
->list
, &rq
->migration_queue
);
1038 * wait_task_inactive - wait for a thread to unschedule.
1040 * The caller must ensure that the task *will* unschedule sometime soon,
1041 * else this function might spin for a *long* time. This function can't
1042 * be called with interrupts off, or it may introduce deadlock with
1043 * smp_call_function() if an IPI is sent by the same process we are
1044 * waiting to become inactive.
1046 void wait_task_inactive(struct task_struct
*p
)
1048 unsigned long flags
;
1054 * We do the initial early heuristics without holding
1055 * any task-queue locks at all. We'll only try to get
1056 * the runqueue lock when things look like they will
1062 * If the task is actively running on another CPU
1063 * still, just relax and busy-wait without holding
1066 * NOTE! Since we don't hold any locks, it's not
1067 * even sure that "rq" stays as the right runqueue!
1068 * But we don't care, since "task_running()" will
1069 * return false if the runqueue has changed and p
1070 * is actually now running somewhere else!
1072 while (task_running(rq
, p
))
1076 * Ok, time to look more closely! We need the rq
1077 * lock now, to be *sure*. If we're wrong, we'll
1078 * just go back and repeat.
1080 rq
= task_rq_lock(p
, &flags
);
1081 running
= task_running(rq
, p
);
1082 on_rq
= p
->se
.on_rq
;
1083 task_rq_unlock(rq
, &flags
);
1086 * Was it really running after all now that we
1087 * checked with the proper locks actually held?
1089 * Oops. Go back and try again..
1091 if (unlikely(running
)) {
1097 * It's not enough that it's not actively running,
1098 * it must be off the runqueue _entirely_, and not
1101 * So if it wa still runnable (but just not actively
1102 * running right now), it's preempted, and we should
1103 * yield - it could be a while.
1105 if (unlikely(on_rq
)) {
1111 * Ahh, all good. It wasn't running, and it wasn't
1112 * runnable, which means that it will never become
1113 * running in the future either. We're all done!
1118 * kick_process - kick a running thread to enter/exit the kernel
1119 * @p: the to-be-kicked thread
1121 * Cause a process which is running on another CPU to enter
1122 * kernel-mode, without any delay. (to get signals handled.)
1124 * NOTE: this function doesnt have to take the runqueue lock,
1125 * because all it wants to ensure is that the remote task enters
1126 * the kernel. If the IPI races and the task has been migrated
1127 * to another CPU then no harm is done and the purpose has been
1130 void kick_process(struct task_struct
*p
)
1136 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1137 smp_send_reschedule(cpu
);
1142 * Return a low guess at the load of a migration-source cpu weighted
1143 * according to the scheduling class and "nice" value.
1145 * We want to under-estimate the load of migration sources, to
1146 * balance conservatively.
1148 static inline unsigned long source_load(int cpu
, int type
)
1150 struct rq
*rq
= cpu_rq(cpu
);
1151 unsigned long total
= weighted_cpuload(cpu
);
1156 return min(rq
->cpu_load
[type
-1], total
);
1160 * Return a high guess at the load of a migration-target cpu weighted
1161 * according to the scheduling class and "nice" value.
1163 static inline unsigned long target_load(int cpu
, int type
)
1165 struct rq
*rq
= cpu_rq(cpu
);
1166 unsigned long total
= weighted_cpuload(cpu
);
1171 return max(rq
->cpu_load
[type
-1], total
);
1175 * Return the average load per task on the cpu's run queue
1177 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1179 struct rq
*rq
= cpu_rq(cpu
);
1180 unsigned long total
= weighted_cpuload(cpu
);
1181 unsigned long n
= rq
->nr_running
;
1183 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1187 * find_idlest_group finds and returns the least busy CPU group within the
1190 static struct sched_group
*
1191 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1193 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1194 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1195 int load_idx
= sd
->forkexec_idx
;
1196 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1199 unsigned long load
, avg_load
;
1203 /* Skip over this group if it has no CPUs allowed */
1204 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1207 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1209 /* Tally up the load of all CPUs in the group */
1212 for_each_cpu_mask(i
, group
->cpumask
) {
1213 /* Bias balancing toward cpus of our domain */
1215 load
= source_load(i
, load_idx
);
1217 load
= target_load(i
, load_idx
);
1222 /* Adjust by relative CPU power of the group */
1223 avg_load
= sg_div_cpu_power(group
,
1224 avg_load
* SCHED_LOAD_SCALE
);
1227 this_load
= avg_load
;
1229 } else if (avg_load
< min_load
) {
1230 min_load
= avg_load
;
1234 group
= group
->next
;
1235 } while (group
!= sd
->groups
);
1237 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1243 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1246 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1249 unsigned long load
, min_load
= ULONG_MAX
;
1253 /* Traverse only the allowed CPUs */
1254 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1256 for_each_cpu_mask(i
, tmp
) {
1257 load
= weighted_cpuload(i
);
1259 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1269 * sched_balance_self: balance the current task (running on cpu) in domains
1270 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1273 * Balance, ie. select the least loaded group.
1275 * Returns the target CPU number, or the same CPU if no balancing is needed.
1277 * preempt must be disabled.
1279 static int sched_balance_self(int cpu
, int flag
)
1281 struct task_struct
*t
= current
;
1282 struct sched_domain
*tmp
, *sd
= NULL
;
1284 for_each_domain(cpu
, tmp
) {
1286 * If power savings logic is enabled for a domain, stop there.
1288 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1290 if (tmp
->flags
& flag
)
1296 struct sched_group
*group
;
1297 int new_cpu
, weight
;
1299 if (!(sd
->flags
& flag
)) {
1305 group
= find_idlest_group(sd
, t
, cpu
);
1311 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1312 if (new_cpu
== -1 || new_cpu
== cpu
) {
1313 /* Now try balancing at a lower domain level of cpu */
1318 /* Now try balancing at a lower domain level of new_cpu */
1321 weight
= cpus_weight(span
);
1322 for_each_domain(cpu
, tmp
) {
1323 if (weight
<= cpus_weight(tmp
->span
))
1325 if (tmp
->flags
& flag
)
1328 /* while loop will break here if sd == NULL */
1334 #endif /* CONFIG_SMP */
1337 * wake_idle() will wake a task on an idle cpu if task->cpu is
1338 * not idle and an idle cpu is available. The span of cpus to
1339 * search starts with cpus closest then further out as needed,
1340 * so we always favor a closer, idle cpu.
1342 * Returns the CPU we should wake onto.
1344 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1345 static int wake_idle(int cpu
, struct task_struct
*p
)
1348 struct sched_domain
*sd
;
1352 * If it is idle, then it is the best cpu to run this task.
1354 * This cpu is also the best, if it has more than one task already.
1355 * Siblings must be also busy(in most cases) as they didn't already
1356 * pickup the extra load from this cpu and hence we need not check
1357 * sibling runqueue info. This will avoid the checks and cache miss
1358 * penalities associated with that.
1360 if (idle_cpu(cpu
) || cpu_rq(cpu
)->nr_running
> 1)
1363 for_each_domain(cpu
, sd
) {
1364 if (sd
->flags
& SD_WAKE_IDLE
) {
1365 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1366 for_each_cpu_mask(i
, tmp
) {
1377 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1384 * try_to_wake_up - wake up a thread
1385 * @p: the to-be-woken-up thread
1386 * @state: the mask of task states that can be woken
1387 * @sync: do a synchronous wakeup?
1389 * Put it on the run-queue if it's not already there. The "current"
1390 * thread is always on the run-queue (except when the actual
1391 * re-schedule is in progress), and as such you're allowed to do
1392 * the simpler "current->state = TASK_RUNNING" to mark yourself
1393 * runnable without the overhead of this.
1395 * returns failure only if the task is already active.
1397 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1399 int cpu
, this_cpu
, success
= 0;
1400 unsigned long flags
;
1404 struct sched_domain
*sd
, *this_sd
= NULL
;
1405 unsigned long load
, this_load
;
1409 rq
= task_rq_lock(p
, &flags
);
1410 old_state
= p
->state
;
1411 if (!(old_state
& state
))
1418 this_cpu
= smp_processor_id();
1421 if (unlikely(task_running(rq
, p
)))
1426 schedstat_inc(rq
, ttwu_cnt
);
1427 if (cpu
== this_cpu
) {
1428 schedstat_inc(rq
, ttwu_local
);
1432 for_each_domain(this_cpu
, sd
) {
1433 if (cpu_isset(cpu
, sd
->span
)) {
1434 schedstat_inc(sd
, ttwu_wake_remote
);
1440 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1444 * Check for affine wakeup and passive balancing possibilities.
1447 int idx
= this_sd
->wake_idx
;
1448 unsigned int imbalance
;
1450 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1452 load
= source_load(cpu
, idx
);
1453 this_load
= target_load(this_cpu
, idx
);
1455 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1457 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1458 unsigned long tl
= this_load
;
1459 unsigned long tl_per_task
;
1461 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1464 * If sync wakeup then subtract the (maximum possible)
1465 * effect of the currently running task from the load
1466 * of the current CPU:
1469 tl
-= current
->se
.load
.weight
;
1472 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1473 100*(tl
+ p
->se
.load
.weight
) <= imbalance
*load
) {
1475 * This domain has SD_WAKE_AFFINE and
1476 * p is cache cold in this domain, and
1477 * there is no bad imbalance.
1479 schedstat_inc(this_sd
, ttwu_move_affine
);
1485 * Start passive balancing when half the imbalance_pct
1488 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1489 if (imbalance
*this_load
<= 100*load
) {
1490 schedstat_inc(this_sd
, ttwu_move_balance
);
1496 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1498 new_cpu
= wake_idle(new_cpu
, p
);
1499 if (new_cpu
!= cpu
) {
1500 set_task_cpu(p
, new_cpu
);
1501 task_rq_unlock(rq
, &flags
);
1502 /* might preempt at this point */
1503 rq
= task_rq_lock(p
, &flags
);
1504 old_state
= p
->state
;
1505 if (!(old_state
& state
))
1510 this_cpu
= smp_processor_id();
1515 #endif /* CONFIG_SMP */
1516 update_rq_clock(rq
);
1517 activate_task(rq
, p
, 1);
1519 * Sync wakeups (i.e. those types of wakeups where the waker
1520 * has indicated that it will leave the CPU in short order)
1521 * don't trigger a preemption, if the woken up task will run on
1522 * this cpu. (in this case the 'I will reschedule' promise of
1523 * the waker guarantees that the freshly woken up task is going
1524 * to be considered on this CPU.)
1526 if (!sync
|| cpu
!= this_cpu
)
1527 check_preempt_curr(rq
, p
);
1531 p
->state
= TASK_RUNNING
;
1533 task_rq_unlock(rq
, &flags
);
1538 int fastcall
wake_up_process(struct task_struct
*p
)
1540 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1541 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1543 EXPORT_SYMBOL(wake_up_process
);
1545 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1547 return try_to_wake_up(p
, state
, 0);
1551 * Perform scheduler related setup for a newly forked process p.
1552 * p is forked by current.
1554 * __sched_fork() is basic setup used by init_idle() too:
1556 static void __sched_fork(struct task_struct
*p
)
1558 p
->se
.wait_start_fair
= 0;
1559 p
->se
.exec_start
= 0;
1560 p
->se
.sum_exec_runtime
= 0;
1561 p
->se
.prev_sum_exec_runtime
= 0;
1562 p
->se
.wait_runtime
= 0;
1563 p
->se
.sleep_start_fair
= 0;
1565 #ifdef CONFIG_SCHEDSTATS
1566 p
->se
.wait_start
= 0;
1567 p
->se
.sum_wait_runtime
= 0;
1568 p
->se
.sum_sleep_runtime
= 0;
1569 p
->se
.sleep_start
= 0;
1570 p
->se
.block_start
= 0;
1571 p
->se
.sleep_max
= 0;
1572 p
->se
.block_max
= 0;
1574 p
->se
.slice_max
= 0;
1576 p
->se
.wait_runtime_overruns
= 0;
1577 p
->se
.wait_runtime_underruns
= 0;
1580 INIT_LIST_HEAD(&p
->run_list
);
1583 #ifdef CONFIG_PREEMPT_NOTIFIERS
1584 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1588 * We mark the process as running here, but have not actually
1589 * inserted it onto the runqueue yet. This guarantees that
1590 * nobody will actually run it, and a signal or other external
1591 * event cannot wake it up and insert it on the runqueue either.
1593 p
->state
= TASK_RUNNING
;
1597 * fork()/clone()-time setup:
1599 void sched_fork(struct task_struct
*p
, int clone_flags
)
1601 int cpu
= get_cpu();
1606 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1608 __set_task_cpu(p
, cpu
);
1611 * Make sure we do not leak PI boosting priority to the child:
1613 p
->prio
= current
->normal_prio
;
1615 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1616 if (likely(sched_info_on()))
1617 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1619 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1622 #ifdef CONFIG_PREEMPT
1623 /* Want to start with kernel preemption disabled. */
1624 task_thread_info(p
)->preempt_count
= 1;
1630 * wake_up_new_task - wake up a newly created task for the first time.
1632 * This function will do some initial scheduler statistics housekeeping
1633 * that must be done for every newly created context, then puts the task
1634 * on the runqueue and wakes it.
1636 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1638 unsigned long flags
;
1642 rq
= task_rq_lock(p
, &flags
);
1643 BUG_ON(p
->state
!= TASK_RUNNING
);
1644 this_cpu
= smp_processor_id(); /* parent's CPU */
1645 update_rq_clock(rq
);
1647 p
->prio
= effective_prio(p
);
1649 if (rt_prio(p
->prio
))
1650 p
->sched_class
= &rt_sched_class
;
1652 p
->sched_class
= &fair_sched_class
;
1654 if (task_cpu(p
) != this_cpu
|| !p
->sched_class
->task_new
||
1655 !current
->se
.on_rq
) {
1656 activate_task(rq
, p
, 0);
1659 * Let the scheduling class do new task startup
1660 * management (if any):
1662 p
->sched_class
->task_new(rq
, p
);
1663 inc_nr_running(p
, rq
);
1665 check_preempt_curr(rq
, p
);
1666 task_rq_unlock(rq
, &flags
);
1669 #ifdef CONFIG_PREEMPT_NOTIFIERS
1672 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
1673 * @notifier: notifier struct to register
1675 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1677 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1679 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1682 * preempt_notifier_unregister - no longer interested in preemption notifications
1683 * @notifier: notifier struct to unregister
1685 * This is safe to call from within a preemption notifier.
1687 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1689 hlist_del(¬ifier
->link
);
1691 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1693 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1695 struct preempt_notifier
*notifier
;
1696 struct hlist_node
*node
;
1698 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1699 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1703 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1704 struct task_struct
*next
)
1706 struct preempt_notifier
*notifier
;
1707 struct hlist_node
*node
;
1709 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1710 notifier
->ops
->sched_out(notifier
, next
);
1715 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1720 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1721 struct task_struct
*next
)
1728 * prepare_task_switch - prepare to switch tasks
1729 * @rq: the runqueue preparing to switch
1730 * @prev: the current task that is being switched out
1731 * @next: the task we are going to switch to.
1733 * This is called with the rq lock held and interrupts off. It must
1734 * be paired with a subsequent finish_task_switch after the context
1737 * prepare_task_switch sets up locking and calls architecture specific
1741 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1742 struct task_struct
*next
)
1744 fire_sched_out_preempt_notifiers(prev
, next
);
1745 prepare_lock_switch(rq
, next
);
1746 prepare_arch_switch(next
);
1750 * finish_task_switch - clean up after a task-switch
1751 * @rq: runqueue associated with task-switch
1752 * @prev: the thread we just switched away from.
1754 * finish_task_switch must be called after the context switch, paired
1755 * with a prepare_task_switch call before the context switch.
1756 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1757 * and do any other architecture-specific cleanup actions.
1759 * Note that we may have delayed dropping an mm in context_switch(). If
1760 * so, we finish that here outside of the runqueue lock. (Doing it
1761 * with the lock held can cause deadlocks; see schedule() for
1764 static inline void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1765 __releases(rq
->lock
)
1767 struct mm_struct
*mm
= rq
->prev_mm
;
1773 * A task struct has one reference for the use as "current".
1774 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1775 * schedule one last time. The schedule call will never return, and
1776 * the scheduled task must drop that reference.
1777 * The test for TASK_DEAD must occur while the runqueue locks are
1778 * still held, otherwise prev could be scheduled on another cpu, die
1779 * there before we look at prev->state, and then the reference would
1781 * Manfred Spraul <manfred@colorfullife.com>
1783 prev_state
= prev
->state
;
1784 finish_arch_switch(prev
);
1785 finish_lock_switch(rq
, prev
);
1786 fire_sched_in_preempt_notifiers(current
);
1789 if (unlikely(prev_state
== TASK_DEAD
)) {
1791 * Remove function-return probe instances associated with this
1792 * task and put them back on the free list.
1794 kprobe_flush_task(prev
);
1795 put_task_struct(prev
);
1800 * schedule_tail - first thing a freshly forked thread must call.
1801 * @prev: the thread we just switched away from.
1803 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1804 __releases(rq
->lock
)
1806 struct rq
*rq
= this_rq();
1808 finish_task_switch(rq
, prev
);
1809 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1810 /* In this case, finish_task_switch does not reenable preemption */
1813 if (current
->set_child_tid
)
1814 put_user(current
->pid
, current
->set_child_tid
);
1818 * context_switch - switch to the new MM and the new
1819 * thread's register state.
1822 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1823 struct task_struct
*next
)
1825 struct mm_struct
*mm
, *oldmm
;
1827 prepare_task_switch(rq
, prev
, next
);
1829 oldmm
= prev
->active_mm
;
1831 * For paravirt, this is coupled with an exit in switch_to to
1832 * combine the page table reload and the switch backend into
1835 arch_enter_lazy_cpu_mode();
1837 if (unlikely(!mm
)) {
1838 next
->active_mm
= oldmm
;
1839 atomic_inc(&oldmm
->mm_count
);
1840 enter_lazy_tlb(oldmm
, next
);
1842 switch_mm(oldmm
, mm
, next
);
1844 if (unlikely(!prev
->mm
)) {
1845 prev
->active_mm
= NULL
;
1846 rq
->prev_mm
= oldmm
;
1849 * Since the runqueue lock will be released by the next
1850 * task (which is an invalid locking op but in the case
1851 * of the scheduler it's an obvious special-case), so we
1852 * do an early lockdep release here:
1854 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1855 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1858 /* Here we just switch the register state and the stack. */
1859 switch_to(prev
, next
, prev
);
1863 * this_rq must be evaluated again because prev may have moved
1864 * CPUs since it called schedule(), thus the 'rq' on its stack
1865 * frame will be invalid.
1867 finish_task_switch(this_rq(), prev
);
1871 * nr_running, nr_uninterruptible and nr_context_switches:
1873 * externally visible scheduler statistics: current number of runnable
1874 * threads, current number of uninterruptible-sleeping threads, total
1875 * number of context switches performed since bootup.
1877 unsigned long nr_running(void)
1879 unsigned long i
, sum
= 0;
1881 for_each_online_cpu(i
)
1882 sum
+= cpu_rq(i
)->nr_running
;
1887 unsigned long nr_uninterruptible(void)
1889 unsigned long i
, sum
= 0;
1891 for_each_possible_cpu(i
)
1892 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1895 * Since we read the counters lockless, it might be slightly
1896 * inaccurate. Do not allow it to go below zero though:
1898 if (unlikely((long)sum
< 0))
1904 unsigned long long nr_context_switches(void)
1907 unsigned long long sum
= 0;
1909 for_each_possible_cpu(i
)
1910 sum
+= cpu_rq(i
)->nr_switches
;
1915 unsigned long nr_iowait(void)
1917 unsigned long i
, sum
= 0;
1919 for_each_possible_cpu(i
)
1920 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1925 unsigned long nr_active(void)
1927 unsigned long i
, running
= 0, uninterruptible
= 0;
1929 for_each_online_cpu(i
) {
1930 running
+= cpu_rq(i
)->nr_running
;
1931 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
1934 if (unlikely((long)uninterruptible
< 0))
1935 uninterruptible
= 0;
1937 return running
+ uninterruptible
;
1941 * Update rq->cpu_load[] statistics. This function is usually called every
1942 * scheduler tick (TICK_NSEC).
1944 static void update_cpu_load(struct rq
*this_rq
)
1946 unsigned long this_load
= this_rq
->ls
.load
.weight
;
1949 this_rq
->nr_load_updates
++;
1951 /* Update our load: */
1952 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
1953 unsigned long old_load
, new_load
;
1955 /* scale is effectively 1 << i now, and >> i divides by scale */
1957 old_load
= this_rq
->cpu_load
[i
];
1958 new_load
= this_load
;
1960 * Round up the averaging division if load is increasing. This
1961 * prevents us from getting stuck on 9 if the load is 10, for
1964 if (new_load
> old_load
)
1965 new_load
+= scale
-1;
1966 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
1973 * double_rq_lock - safely lock two runqueues
1975 * Note this does not disable interrupts like task_rq_lock,
1976 * you need to do so manually before calling.
1978 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
1979 __acquires(rq1
->lock
)
1980 __acquires(rq2
->lock
)
1982 BUG_ON(!irqs_disabled());
1984 spin_lock(&rq1
->lock
);
1985 __acquire(rq2
->lock
); /* Fake it out ;) */
1988 spin_lock(&rq1
->lock
);
1989 spin_lock(&rq2
->lock
);
1991 spin_lock(&rq2
->lock
);
1992 spin_lock(&rq1
->lock
);
1995 update_rq_clock(rq1
);
1996 update_rq_clock(rq2
);
2000 * double_rq_unlock - safely unlock two runqueues
2002 * Note this does not restore interrupts like task_rq_unlock,
2003 * you need to do so manually after calling.
2005 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2006 __releases(rq1
->lock
)
2007 __releases(rq2
->lock
)
2009 spin_unlock(&rq1
->lock
);
2011 spin_unlock(&rq2
->lock
);
2013 __release(rq2
->lock
);
2017 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2019 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2020 __releases(this_rq
->lock
)
2021 __acquires(busiest
->lock
)
2022 __acquires(this_rq
->lock
)
2024 if (unlikely(!irqs_disabled())) {
2025 /* printk() doesn't work good under rq->lock */
2026 spin_unlock(&this_rq
->lock
);
2029 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2030 if (busiest
< this_rq
) {
2031 spin_unlock(&this_rq
->lock
);
2032 spin_lock(&busiest
->lock
);
2033 spin_lock(&this_rq
->lock
);
2035 spin_lock(&busiest
->lock
);
2040 * If dest_cpu is allowed for this process, migrate the task to it.
2041 * This is accomplished by forcing the cpu_allowed mask to only
2042 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2043 * the cpu_allowed mask is restored.
2045 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2047 struct migration_req req
;
2048 unsigned long flags
;
2051 rq
= task_rq_lock(p
, &flags
);
2052 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2053 || unlikely(cpu_is_offline(dest_cpu
)))
2056 /* force the process onto the specified CPU */
2057 if (migrate_task(p
, dest_cpu
, &req
)) {
2058 /* Need to wait for migration thread (might exit: take ref). */
2059 struct task_struct
*mt
= rq
->migration_thread
;
2061 get_task_struct(mt
);
2062 task_rq_unlock(rq
, &flags
);
2063 wake_up_process(mt
);
2064 put_task_struct(mt
);
2065 wait_for_completion(&req
.done
);
2070 task_rq_unlock(rq
, &flags
);
2074 * sched_exec - execve() is a valuable balancing opportunity, because at
2075 * this point the task has the smallest effective memory and cache footprint.
2077 void sched_exec(void)
2079 int new_cpu
, this_cpu
= get_cpu();
2080 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2082 if (new_cpu
!= this_cpu
)
2083 sched_migrate_task(current
, new_cpu
);
2087 * pull_task - move a task from a remote runqueue to the local runqueue.
2088 * Both runqueues must be locked.
2090 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2091 struct rq
*this_rq
, int this_cpu
)
2093 deactivate_task(src_rq
, p
, 0);
2094 set_task_cpu(p
, this_cpu
);
2095 activate_task(this_rq
, p
, 0);
2097 * Note that idle threads have a prio of MAX_PRIO, for this test
2098 * to be always true for them.
2100 check_preempt_curr(this_rq
, p
);
2104 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2107 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2108 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2112 * We do not migrate tasks that are:
2113 * 1) running (obviously), or
2114 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2115 * 3) are cache-hot on their current CPU.
2117 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
2121 if (task_running(rq
, p
))
2127 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2128 unsigned long max_nr_move
, unsigned long max_load_move
,
2129 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2130 int *all_pinned
, unsigned long *load_moved
,
2131 int *this_best_prio
, struct rq_iterator
*iterator
)
2133 int pulled
= 0, pinned
= 0, skip_for_load
;
2134 struct task_struct
*p
;
2135 long rem_load_move
= max_load_move
;
2137 if (max_nr_move
== 0 || max_load_move
== 0)
2143 * Start the load-balancing iterator:
2145 p
= iterator
->start(iterator
->arg
);
2150 * To help distribute high priority tasks accross CPUs we don't
2151 * skip a task if it will be the highest priority task (i.e. smallest
2152 * prio value) on its new queue regardless of its load weight
2154 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2155 SCHED_LOAD_SCALE_FUZZ
;
2156 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2157 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2158 p
= iterator
->next(iterator
->arg
);
2162 pull_task(busiest
, p
, this_rq
, this_cpu
);
2164 rem_load_move
-= p
->se
.load
.weight
;
2167 * We only want to steal up to the prescribed number of tasks
2168 * and the prescribed amount of weighted load.
2170 if (pulled
< max_nr_move
&& rem_load_move
> 0) {
2171 if (p
->prio
< *this_best_prio
)
2172 *this_best_prio
= p
->prio
;
2173 p
= iterator
->next(iterator
->arg
);
2178 * Right now, this is the only place pull_task() is called,
2179 * so we can safely collect pull_task() stats here rather than
2180 * inside pull_task().
2182 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2185 *all_pinned
= pinned
;
2186 *load_moved
= max_load_move
- rem_load_move
;
2191 * move_tasks tries to move up to max_load_move weighted load from busiest to
2192 * this_rq, as part of a balancing operation within domain "sd".
2193 * Returns 1 if successful and 0 otherwise.
2195 * Called with both runqueues locked.
2197 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2198 unsigned long max_load_move
,
2199 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2202 struct sched_class
*class = sched_class_highest
;
2203 unsigned long total_load_moved
= 0;
2204 int this_best_prio
= this_rq
->curr
->prio
;
2208 class->load_balance(this_rq
, this_cpu
, busiest
,
2209 ULONG_MAX
, max_load_move
- total_load_moved
,
2210 sd
, idle
, all_pinned
, &this_best_prio
);
2211 class = class->next
;
2212 } while (class && max_load_move
> total_load_moved
);
2214 return total_load_moved
> 0;
2218 * move_one_task tries to move exactly one task from busiest to this_rq, as
2219 * part of active balancing operations within "domain".
2220 * Returns 1 if successful and 0 otherwise.
2222 * Called with both runqueues locked.
2224 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2225 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2227 struct sched_class
*class;
2228 int this_best_prio
= MAX_PRIO
;
2230 for (class = sched_class_highest
; class; class = class->next
)
2231 if (class->load_balance(this_rq
, this_cpu
, busiest
,
2232 1, ULONG_MAX
, sd
, idle
, NULL
,
2240 * find_busiest_group finds and returns the busiest CPU group within the
2241 * domain. It calculates and returns the amount of weighted load which
2242 * should be moved to restore balance via the imbalance parameter.
2244 static struct sched_group
*
2245 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2246 unsigned long *imbalance
, enum cpu_idle_type idle
,
2247 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2249 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2250 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2251 unsigned long max_pull
;
2252 unsigned long busiest_load_per_task
, busiest_nr_running
;
2253 unsigned long this_load_per_task
, this_nr_running
;
2255 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2256 int power_savings_balance
= 1;
2257 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2258 unsigned long min_nr_running
= ULONG_MAX
;
2259 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2262 max_load
= this_load
= total_load
= total_pwr
= 0;
2263 busiest_load_per_task
= busiest_nr_running
= 0;
2264 this_load_per_task
= this_nr_running
= 0;
2265 if (idle
== CPU_NOT_IDLE
)
2266 load_idx
= sd
->busy_idx
;
2267 else if (idle
== CPU_NEWLY_IDLE
)
2268 load_idx
= sd
->newidle_idx
;
2270 load_idx
= sd
->idle_idx
;
2273 unsigned long load
, group_capacity
;
2276 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2277 unsigned long sum_nr_running
, sum_weighted_load
;
2279 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2282 balance_cpu
= first_cpu(group
->cpumask
);
2284 /* Tally up the load of all CPUs in the group */
2285 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2287 for_each_cpu_mask(i
, group
->cpumask
) {
2290 if (!cpu_isset(i
, *cpus
))
2295 if (*sd_idle
&& rq
->nr_running
)
2298 /* Bias balancing toward cpus of our domain */
2300 if (idle_cpu(i
) && !first_idle_cpu
) {
2305 load
= target_load(i
, load_idx
);
2307 load
= source_load(i
, load_idx
);
2310 sum_nr_running
+= rq
->nr_running
;
2311 sum_weighted_load
+= weighted_cpuload(i
);
2315 * First idle cpu or the first cpu(busiest) in this sched group
2316 * is eligible for doing load balancing at this and above
2317 * domains. In the newly idle case, we will allow all the cpu's
2318 * to do the newly idle load balance.
2320 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2321 balance_cpu
!= this_cpu
&& balance
) {
2326 total_load
+= avg_load
;
2327 total_pwr
+= group
->__cpu_power
;
2329 /* Adjust by relative CPU power of the group */
2330 avg_load
= sg_div_cpu_power(group
,
2331 avg_load
* SCHED_LOAD_SCALE
);
2333 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2336 this_load
= avg_load
;
2338 this_nr_running
= sum_nr_running
;
2339 this_load_per_task
= sum_weighted_load
;
2340 } else if (avg_load
> max_load
&&
2341 sum_nr_running
> group_capacity
) {
2342 max_load
= avg_load
;
2344 busiest_nr_running
= sum_nr_running
;
2345 busiest_load_per_task
= sum_weighted_load
;
2348 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2350 * Busy processors will not participate in power savings
2353 if (idle
== CPU_NOT_IDLE
||
2354 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2358 * If the local group is idle or completely loaded
2359 * no need to do power savings balance at this domain
2361 if (local_group
&& (this_nr_running
>= group_capacity
||
2363 power_savings_balance
= 0;
2366 * If a group is already running at full capacity or idle,
2367 * don't include that group in power savings calculations
2369 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2374 * Calculate the group which has the least non-idle load.
2375 * This is the group from where we need to pick up the load
2378 if ((sum_nr_running
< min_nr_running
) ||
2379 (sum_nr_running
== min_nr_running
&&
2380 first_cpu(group
->cpumask
) <
2381 first_cpu(group_min
->cpumask
))) {
2383 min_nr_running
= sum_nr_running
;
2384 min_load_per_task
= sum_weighted_load
/
2389 * Calculate the group which is almost near its
2390 * capacity but still has some space to pick up some load
2391 * from other group and save more power
2393 if (sum_nr_running
<= group_capacity
- 1) {
2394 if (sum_nr_running
> leader_nr_running
||
2395 (sum_nr_running
== leader_nr_running
&&
2396 first_cpu(group
->cpumask
) >
2397 first_cpu(group_leader
->cpumask
))) {
2398 group_leader
= group
;
2399 leader_nr_running
= sum_nr_running
;
2404 group
= group
->next
;
2405 } while (group
!= sd
->groups
);
2407 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2410 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2412 if (this_load
>= avg_load
||
2413 100*max_load
<= sd
->imbalance_pct
*this_load
)
2416 busiest_load_per_task
/= busiest_nr_running
;
2418 * We're trying to get all the cpus to the average_load, so we don't
2419 * want to push ourselves above the average load, nor do we wish to
2420 * reduce the max loaded cpu below the average load, as either of these
2421 * actions would just result in more rebalancing later, and ping-pong
2422 * tasks around. Thus we look for the minimum possible imbalance.
2423 * Negative imbalances (*we* are more loaded than anyone else) will
2424 * be counted as no imbalance for these purposes -- we can't fix that
2425 * by pulling tasks to us. Be careful of negative numbers as they'll
2426 * appear as very large values with unsigned longs.
2428 if (max_load
<= busiest_load_per_task
)
2432 * In the presence of smp nice balancing, certain scenarios can have
2433 * max load less than avg load(as we skip the groups at or below
2434 * its cpu_power, while calculating max_load..)
2436 if (max_load
< avg_load
) {
2438 goto small_imbalance
;
2441 /* Don't want to pull so many tasks that a group would go idle */
2442 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2444 /* How much load to actually move to equalise the imbalance */
2445 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2446 (avg_load
- this_load
) * this->__cpu_power
)
2450 * if *imbalance is less than the average load per runnable task
2451 * there is no gaurantee that any tasks will be moved so we'll have
2452 * a think about bumping its value to force at least one task to be
2455 if (*imbalance
< busiest_load_per_task
) {
2456 unsigned long tmp
, pwr_now
, pwr_move
;
2460 pwr_move
= pwr_now
= 0;
2462 if (this_nr_running
) {
2463 this_load_per_task
/= this_nr_running
;
2464 if (busiest_load_per_task
> this_load_per_task
)
2467 this_load_per_task
= SCHED_LOAD_SCALE
;
2469 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
2470 busiest_load_per_task
* imbn
) {
2471 *imbalance
= busiest_load_per_task
;
2476 * OK, we don't have enough imbalance to justify moving tasks,
2477 * however we may be able to increase total CPU power used by
2481 pwr_now
+= busiest
->__cpu_power
*
2482 min(busiest_load_per_task
, max_load
);
2483 pwr_now
+= this->__cpu_power
*
2484 min(this_load_per_task
, this_load
);
2485 pwr_now
/= SCHED_LOAD_SCALE
;
2487 /* Amount of load we'd subtract */
2488 tmp
= sg_div_cpu_power(busiest
,
2489 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2491 pwr_move
+= busiest
->__cpu_power
*
2492 min(busiest_load_per_task
, max_load
- tmp
);
2494 /* Amount of load we'd add */
2495 if (max_load
* busiest
->__cpu_power
<
2496 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2497 tmp
= sg_div_cpu_power(this,
2498 max_load
* busiest
->__cpu_power
);
2500 tmp
= sg_div_cpu_power(this,
2501 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2502 pwr_move
+= this->__cpu_power
*
2503 min(this_load_per_task
, this_load
+ tmp
);
2504 pwr_move
/= SCHED_LOAD_SCALE
;
2506 /* Move if we gain throughput */
2507 if (pwr_move
> pwr_now
)
2508 *imbalance
= busiest_load_per_task
;
2514 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2515 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2518 if (this == group_leader
&& group_leader
!= group_min
) {
2519 *imbalance
= min_load_per_task
;
2529 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2532 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
2533 unsigned long imbalance
, cpumask_t
*cpus
)
2535 struct rq
*busiest
= NULL
, *rq
;
2536 unsigned long max_load
= 0;
2539 for_each_cpu_mask(i
, group
->cpumask
) {
2542 if (!cpu_isset(i
, *cpus
))
2546 wl
= weighted_cpuload(i
);
2548 if (rq
->nr_running
== 1 && wl
> imbalance
)
2551 if (wl
> max_load
) {
2561 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2562 * so long as it is large enough.
2564 #define MAX_PINNED_INTERVAL 512
2567 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2568 * tasks if there is an imbalance.
2570 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2571 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2574 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2575 struct sched_group
*group
;
2576 unsigned long imbalance
;
2578 cpumask_t cpus
= CPU_MASK_ALL
;
2579 unsigned long flags
;
2582 * When power savings policy is enabled for the parent domain, idle
2583 * sibling can pick up load irrespective of busy siblings. In this case,
2584 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2585 * portraying it as CPU_NOT_IDLE.
2587 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2588 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2591 schedstat_inc(sd
, lb_cnt
[idle
]);
2594 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2601 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2605 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2607 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2611 BUG_ON(busiest
== this_rq
);
2613 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2616 if (busiest
->nr_running
> 1) {
2618 * Attempt to move tasks. If find_busiest_group has found
2619 * an imbalance but busiest->nr_running <= 1, the group is
2620 * still unbalanced. ld_moved simply stays zero, so it is
2621 * correctly treated as an imbalance.
2623 local_irq_save(flags
);
2624 double_rq_lock(this_rq
, busiest
);
2625 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2626 imbalance
, sd
, idle
, &all_pinned
);
2627 double_rq_unlock(this_rq
, busiest
);
2628 local_irq_restore(flags
);
2631 * some other cpu did the load balance for us.
2633 if (ld_moved
&& this_cpu
!= smp_processor_id())
2634 resched_cpu(this_cpu
);
2636 /* All tasks on this runqueue were pinned by CPU affinity */
2637 if (unlikely(all_pinned
)) {
2638 cpu_clear(cpu_of(busiest
), cpus
);
2639 if (!cpus_empty(cpus
))
2646 schedstat_inc(sd
, lb_failed
[idle
]);
2647 sd
->nr_balance_failed
++;
2649 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2651 spin_lock_irqsave(&busiest
->lock
, flags
);
2653 /* don't kick the migration_thread, if the curr
2654 * task on busiest cpu can't be moved to this_cpu
2656 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2657 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2659 goto out_one_pinned
;
2662 if (!busiest
->active_balance
) {
2663 busiest
->active_balance
= 1;
2664 busiest
->push_cpu
= this_cpu
;
2667 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2669 wake_up_process(busiest
->migration_thread
);
2672 * We've kicked active balancing, reset the failure
2675 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2678 sd
->nr_balance_failed
= 0;
2680 if (likely(!active_balance
)) {
2681 /* We were unbalanced, so reset the balancing interval */
2682 sd
->balance_interval
= sd
->min_interval
;
2685 * If we've begun active balancing, start to back off. This
2686 * case may not be covered by the all_pinned logic if there
2687 * is only 1 task on the busy runqueue (because we don't call
2690 if (sd
->balance_interval
< sd
->max_interval
)
2691 sd
->balance_interval
*= 2;
2694 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2695 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2700 schedstat_inc(sd
, lb_balanced
[idle
]);
2702 sd
->nr_balance_failed
= 0;
2705 /* tune up the balancing interval */
2706 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2707 (sd
->balance_interval
< sd
->max_interval
))
2708 sd
->balance_interval
*= 2;
2710 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2711 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2717 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2718 * tasks if there is an imbalance.
2720 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2721 * this_rq is locked.
2724 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2726 struct sched_group
*group
;
2727 struct rq
*busiest
= NULL
;
2728 unsigned long imbalance
;
2732 cpumask_t cpus
= CPU_MASK_ALL
;
2735 * When power savings policy is enabled for the parent domain, idle
2736 * sibling can pick up load irrespective of busy siblings. In this case,
2737 * let the state of idle sibling percolate up as IDLE, instead of
2738 * portraying it as CPU_NOT_IDLE.
2740 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2741 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2744 schedstat_inc(sd
, lb_cnt
[CPU_NEWLY_IDLE
]);
2746 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
2747 &sd_idle
, &cpus
, NULL
);
2749 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
2753 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
2756 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
2760 BUG_ON(busiest
== this_rq
);
2762 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
2765 if (busiest
->nr_running
> 1) {
2766 /* Attempt to move tasks */
2767 double_lock_balance(this_rq
, busiest
);
2768 /* this_rq->clock is already updated */
2769 update_rq_clock(busiest
);
2770 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2771 imbalance
, sd
, CPU_NEWLY_IDLE
,
2773 spin_unlock(&busiest
->lock
);
2775 if (unlikely(all_pinned
)) {
2776 cpu_clear(cpu_of(busiest
), cpus
);
2777 if (!cpus_empty(cpus
))
2783 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
2784 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2785 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2788 sd
->nr_balance_failed
= 0;
2793 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
2794 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2795 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2797 sd
->nr_balance_failed
= 0;
2803 * idle_balance is called by schedule() if this_cpu is about to become
2804 * idle. Attempts to pull tasks from other CPUs.
2806 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2808 struct sched_domain
*sd
;
2809 int pulled_task
= -1;
2810 unsigned long next_balance
= jiffies
+ HZ
;
2812 for_each_domain(this_cpu
, sd
) {
2813 unsigned long interval
;
2815 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2818 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
2819 /* If we've pulled tasks over stop searching: */
2820 pulled_task
= load_balance_newidle(this_cpu
,
2823 interval
= msecs_to_jiffies(sd
->balance_interval
);
2824 if (time_after(next_balance
, sd
->last_balance
+ interval
))
2825 next_balance
= sd
->last_balance
+ interval
;
2829 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
2831 * We are going idle. next_balance may be set based on
2832 * a busy processor. So reset next_balance.
2834 this_rq
->next_balance
= next_balance
;
2839 * active_load_balance is run by migration threads. It pushes running tasks
2840 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2841 * running on each physical CPU where possible, and avoids physical /
2842 * logical imbalances.
2844 * Called with busiest_rq locked.
2846 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
2848 int target_cpu
= busiest_rq
->push_cpu
;
2849 struct sched_domain
*sd
;
2850 struct rq
*target_rq
;
2852 /* Is there any task to move? */
2853 if (busiest_rq
->nr_running
<= 1)
2856 target_rq
= cpu_rq(target_cpu
);
2859 * This condition is "impossible", if it occurs
2860 * we need to fix it. Originally reported by
2861 * Bjorn Helgaas on a 128-cpu setup.
2863 BUG_ON(busiest_rq
== target_rq
);
2865 /* move a task from busiest_rq to target_rq */
2866 double_lock_balance(busiest_rq
, target_rq
);
2867 update_rq_clock(busiest_rq
);
2868 update_rq_clock(target_rq
);
2870 /* Search for an sd spanning us and the target CPU. */
2871 for_each_domain(target_cpu
, sd
) {
2872 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2873 cpu_isset(busiest_cpu
, sd
->span
))
2878 schedstat_inc(sd
, alb_cnt
);
2880 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
2882 schedstat_inc(sd
, alb_pushed
);
2884 schedstat_inc(sd
, alb_failed
);
2886 spin_unlock(&target_rq
->lock
);
2891 atomic_t load_balancer
;
2893 } nohz ____cacheline_aligned
= {
2894 .load_balancer
= ATOMIC_INIT(-1),
2895 .cpu_mask
= CPU_MASK_NONE
,
2899 * This routine will try to nominate the ilb (idle load balancing)
2900 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
2901 * load balancing on behalf of all those cpus. If all the cpus in the system
2902 * go into this tickless mode, then there will be no ilb owner (as there is
2903 * no need for one) and all the cpus will sleep till the next wakeup event
2906 * For the ilb owner, tick is not stopped. And this tick will be used
2907 * for idle load balancing. ilb owner will still be part of
2910 * While stopping the tick, this cpu will become the ilb owner if there
2911 * is no other owner. And will be the owner till that cpu becomes busy
2912 * or if all cpus in the system stop their ticks at which point
2913 * there is no need for ilb owner.
2915 * When the ilb owner becomes busy, it nominates another owner, during the
2916 * next busy scheduler_tick()
2918 int select_nohz_load_balancer(int stop_tick
)
2920 int cpu
= smp_processor_id();
2923 cpu_set(cpu
, nohz
.cpu_mask
);
2924 cpu_rq(cpu
)->in_nohz_recently
= 1;
2927 * If we are going offline and still the leader, give up!
2929 if (cpu_is_offline(cpu
) &&
2930 atomic_read(&nohz
.load_balancer
) == cpu
) {
2931 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
2936 /* time for ilb owner also to sleep */
2937 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
2938 if (atomic_read(&nohz
.load_balancer
) == cpu
)
2939 atomic_set(&nohz
.load_balancer
, -1);
2943 if (atomic_read(&nohz
.load_balancer
) == -1) {
2944 /* make me the ilb owner */
2945 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
2947 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
2950 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
2953 cpu_clear(cpu
, nohz
.cpu_mask
);
2955 if (atomic_read(&nohz
.load_balancer
) == cpu
)
2956 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
2963 static DEFINE_SPINLOCK(balancing
);
2966 * It checks each scheduling domain to see if it is due to be balanced,
2967 * and initiates a balancing operation if so.
2969 * Balancing parameters are set up in arch_init_sched_domains.
2971 static inline void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
2974 struct rq
*rq
= cpu_rq(cpu
);
2975 unsigned long interval
;
2976 struct sched_domain
*sd
;
2977 /* Earliest time when we have to do rebalance again */
2978 unsigned long next_balance
= jiffies
+ 60*HZ
;
2979 int update_next_balance
= 0;
2981 for_each_domain(cpu
, sd
) {
2982 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2985 interval
= sd
->balance_interval
;
2986 if (idle
!= CPU_IDLE
)
2987 interval
*= sd
->busy_factor
;
2989 /* scale ms to jiffies */
2990 interval
= msecs_to_jiffies(interval
);
2991 if (unlikely(!interval
))
2993 if (interval
> HZ
*NR_CPUS
/10)
2994 interval
= HZ
*NR_CPUS
/10;
2997 if (sd
->flags
& SD_SERIALIZE
) {
2998 if (!spin_trylock(&balancing
))
3002 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3003 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3005 * We've pulled tasks over so either we're no
3006 * longer idle, or one of our SMT siblings is
3009 idle
= CPU_NOT_IDLE
;
3011 sd
->last_balance
= jiffies
;
3013 if (sd
->flags
& SD_SERIALIZE
)
3014 spin_unlock(&balancing
);
3016 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3017 next_balance
= sd
->last_balance
+ interval
;
3018 update_next_balance
= 1;
3022 * Stop the load balance at this level. There is another
3023 * CPU in our sched group which is doing load balancing more
3031 * next_balance will be updated only when there is a need.
3032 * When the cpu is attached to null domain for ex, it will not be
3035 if (likely(update_next_balance
))
3036 rq
->next_balance
= next_balance
;
3040 * run_rebalance_domains is triggered when needed from the scheduler tick.
3041 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3042 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3044 static void run_rebalance_domains(struct softirq_action
*h
)
3046 int this_cpu
= smp_processor_id();
3047 struct rq
*this_rq
= cpu_rq(this_cpu
);
3048 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3049 CPU_IDLE
: CPU_NOT_IDLE
;
3051 rebalance_domains(this_cpu
, idle
);
3055 * If this cpu is the owner for idle load balancing, then do the
3056 * balancing on behalf of the other idle cpus whose ticks are
3059 if (this_rq
->idle_at_tick
&&
3060 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3061 cpumask_t cpus
= nohz
.cpu_mask
;
3065 cpu_clear(this_cpu
, cpus
);
3066 for_each_cpu_mask(balance_cpu
, cpus
) {
3068 * If this cpu gets work to do, stop the load balancing
3069 * work being done for other cpus. Next load
3070 * balancing owner will pick it up.
3075 rebalance_domains(balance_cpu
, CPU_IDLE
);
3077 rq
= cpu_rq(balance_cpu
);
3078 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3079 this_rq
->next_balance
= rq
->next_balance
;
3086 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3088 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3089 * idle load balancing owner or decide to stop the periodic load balancing,
3090 * if the whole system is idle.
3092 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3096 * If we were in the nohz mode recently and busy at the current
3097 * scheduler tick, then check if we need to nominate new idle
3100 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3101 rq
->in_nohz_recently
= 0;
3103 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3104 cpu_clear(cpu
, nohz
.cpu_mask
);
3105 atomic_set(&nohz
.load_balancer
, -1);
3108 if (atomic_read(&nohz
.load_balancer
) == -1) {
3110 * simple selection for now: Nominate the
3111 * first cpu in the nohz list to be the next
3114 * TBD: Traverse the sched domains and nominate
3115 * the nearest cpu in the nohz.cpu_mask.
3117 int ilb
= first_cpu(nohz
.cpu_mask
);
3125 * If this cpu is idle and doing idle load balancing for all the
3126 * cpus with ticks stopped, is it time for that to stop?
3128 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3129 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3135 * If this cpu is idle and the idle load balancing is done by
3136 * someone else, then no need raise the SCHED_SOFTIRQ
3138 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3139 cpu_isset(cpu
, nohz
.cpu_mask
))
3142 if (time_after_eq(jiffies
, rq
->next_balance
))
3143 raise_softirq(SCHED_SOFTIRQ
);
3146 #else /* CONFIG_SMP */
3149 * on UP we do not need to balance between CPUs:
3151 static inline void idle_balance(int cpu
, struct rq
*rq
)
3155 /* Avoid "used but not defined" warning on UP */
3156 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
3157 unsigned long max_nr_move
, unsigned long max_load_move
,
3158 struct sched_domain
*sd
, enum cpu_idle_type idle
,
3159 int *all_pinned
, unsigned long *load_moved
,
3160 int *this_best_prio
, struct rq_iterator
*iterator
)
3169 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3171 EXPORT_PER_CPU_SYMBOL(kstat
);
3174 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3175 * that have not yet been banked in case the task is currently running.
3177 unsigned long long task_sched_runtime(struct task_struct
*p
)
3179 unsigned long flags
;
3183 rq
= task_rq_lock(p
, &flags
);
3184 ns
= p
->se
.sum_exec_runtime
;
3185 if (rq
->curr
== p
) {
3186 update_rq_clock(rq
);
3187 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3188 if ((s64
)delta_exec
> 0)
3191 task_rq_unlock(rq
, &flags
);
3197 * Account user cpu time to a process.
3198 * @p: the process that the cpu time gets accounted to
3199 * @hardirq_offset: the offset to subtract from hardirq_count()
3200 * @cputime: the cpu time spent in user space since the last update
3202 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3204 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3207 p
->utime
= cputime_add(p
->utime
, cputime
);
3209 /* Add user time to cpustat. */
3210 tmp
= cputime_to_cputime64(cputime
);
3211 if (TASK_NICE(p
) > 0)
3212 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3214 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3218 * Account system cpu time to a process.
3219 * @p: the process that the cpu time gets accounted to
3220 * @hardirq_offset: the offset to subtract from hardirq_count()
3221 * @cputime: the cpu time spent in kernel space since the last update
3223 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3226 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3227 struct rq
*rq
= this_rq();
3230 p
->stime
= cputime_add(p
->stime
, cputime
);
3232 /* Add system time to cpustat. */
3233 tmp
= cputime_to_cputime64(cputime
);
3234 if (hardirq_count() - hardirq_offset
)
3235 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3236 else if (softirq_count())
3237 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3238 else if (p
!= rq
->idle
)
3239 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3240 else if (atomic_read(&rq
->nr_iowait
) > 0)
3241 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3243 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3244 /* Account for system time used */
3245 acct_update_integrals(p
);
3249 * Account for involuntary wait time.
3250 * @p: the process from which the cpu time has been stolen
3251 * @steal: the cpu time spent in involuntary wait
3253 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3255 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3256 cputime64_t tmp
= cputime_to_cputime64(steal
);
3257 struct rq
*rq
= this_rq();
3259 if (p
== rq
->idle
) {
3260 p
->stime
= cputime_add(p
->stime
, steal
);
3261 if (atomic_read(&rq
->nr_iowait
) > 0)
3262 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3264 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3266 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3270 * This function gets called by the timer code, with HZ frequency.
3271 * We call it with interrupts disabled.
3273 * It also gets called by the fork code, when changing the parent's
3276 void scheduler_tick(void)
3278 int cpu
= smp_processor_id();
3279 struct rq
*rq
= cpu_rq(cpu
);
3280 struct task_struct
*curr
= rq
->curr
;
3281 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3283 spin_lock(&rq
->lock
);
3284 __update_rq_clock(rq
);
3286 * Let rq->clock advance by at least TICK_NSEC:
3288 if (unlikely(rq
->clock
< next_tick
))
3289 rq
->clock
= next_tick
;
3290 rq
->tick_timestamp
= rq
->clock
;
3291 update_cpu_load(rq
);
3292 if (curr
!= rq
->idle
) /* FIXME: needed? */
3293 curr
->sched_class
->task_tick(rq
, curr
);
3294 spin_unlock(&rq
->lock
);
3297 rq
->idle_at_tick
= idle_cpu(cpu
);
3298 trigger_load_balance(rq
, cpu
);
3302 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3304 void fastcall
add_preempt_count(int val
)
3309 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3311 preempt_count() += val
;
3313 * Spinlock count overflowing soon?
3315 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3318 EXPORT_SYMBOL(add_preempt_count
);
3320 void fastcall
sub_preempt_count(int val
)
3325 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3328 * Is the spinlock portion underflowing?
3330 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3331 !(preempt_count() & PREEMPT_MASK
)))
3334 preempt_count() -= val
;
3336 EXPORT_SYMBOL(sub_preempt_count
);
3341 * Print scheduling while atomic bug:
3343 static noinline
void __schedule_bug(struct task_struct
*prev
)
3345 printk(KERN_ERR
"BUG: scheduling while atomic: %s/0x%08x/%d\n",
3346 prev
->comm
, preempt_count(), prev
->pid
);
3347 debug_show_held_locks(prev
);
3348 if (irqs_disabled())
3349 print_irqtrace_events(prev
);
3354 * Various schedule()-time debugging checks and statistics:
3356 static inline void schedule_debug(struct task_struct
*prev
)
3359 * Test if we are atomic. Since do_exit() needs to call into
3360 * schedule() atomically, we ignore that path for now.
3361 * Otherwise, whine if we are scheduling when we should not be.
3363 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3364 __schedule_bug(prev
);
3366 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3368 schedstat_inc(this_rq(), sched_cnt
);
3372 * Pick up the highest-prio task:
3374 static inline struct task_struct
*
3375 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3377 struct sched_class
*class;
3378 struct task_struct
*p
;
3381 * Optimization: we know that if all tasks are in
3382 * the fair class we can call that function directly:
3384 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3385 p
= fair_sched_class
.pick_next_task(rq
);
3390 class = sched_class_highest
;
3392 p
= class->pick_next_task(rq
);
3396 * Will never be NULL as the idle class always
3397 * returns a non-NULL p:
3399 class = class->next
;
3404 * schedule() is the main scheduler function.
3406 asmlinkage
void __sched
schedule(void)
3408 struct task_struct
*prev
, *next
;
3415 cpu
= smp_processor_id();
3419 switch_count
= &prev
->nivcsw
;
3421 release_kernel_lock(prev
);
3422 need_resched_nonpreemptible
:
3424 schedule_debug(prev
);
3426 spin_lock_irq(&rq
->lock
);
3427 clear_tsk_need_resched(prev
);
3428 __update_rq_clock(rq
);
3430 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3431 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3432 unlikely(signal_pending(prev
)))) {
3433 prev
->state
= TASK_RUNNING
;
3435 deactivate_task(rq
, prev
, 1);
3437 switch_count
= &prev
->nvcsw
;
3440 if (unlikely(!rq
->nr_running
))
3441 idle_balance(cpu
, rq
);
3443 prev
->sched_class
->put_prev_task(rq
, prev
);
3444 next
= pick_next_task(rq
, prev
);
3446 sched_info_switch(prev
, next
);
3448 if (likely(prev
!= next
)) {
3453 context_switch(rq
, prev
, next
); /* unlocks the rq */
3455 spin_unlock_irq(&rq
->lock
);
3457 if (unlikely(reacquire_kernel_lock(current
) < 0)) {
3458 cpu
= smp_processor_id();
3460 goto need_resched_nonpreemptible
;
3462 preempt_enable_no_resched();
3463 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3466 EXPORT_SYMBOL(schedule
);
3468 #ifdef CONFIG_PREEMPT
3470 * this is the entry point to schedule() from in-kernel preemption
3471 * off of preempt_enable. Kernel preemptions off return from interrupt
3472 * occur there and call schedule directly.
3474 asmlinkage
void __sched
preempt_schedule(void)
3476 struct thread_info
*ti
= current_thread_info();
3477 #ifdef CONFIG_PREEMPT_BKL
3478 struct task_struct
*task
= current
;
3479 int saved_lock_depth
;
3482 * If there is a non-zero preempt_count or interrupts are disabled,
3483 * we do not want to preempt the current task. Just return..
3485 if (likely(ti
->preempt_count
|| irqs_disabled()))
3489 add_preempt_count(PREEMPT_ACTIVE
);
3491 * We keep the big kernel semaphore locked, but we
3492 * clear ->lock_depth so that schedule() doesnt
3493 * auto-release the semaphore:
3495 #ifdef CONFIG_PREEMPT_BKL
3496 saved_lock_depth
= task
->lock_depth
;
3497 task
->lock_depth
= -1;
3500 #ifdef CONFIG_PREEMPT_BKL
3501 task
->lock_depth
= saved_lock_depth
;
3503 sub_preempt_count(PREEMPT_ACTIVE
);
3505 /* we could miss a preemption opportunity between schedule and now */
3507 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3510 EXPORT_SYMBOL(preempt_schedule
);
3513 * this is the entry point to schedule() from kernel preemption
3514 * off of irq context.
3515 * Note, that this is called and return with irqs disabled. This will
3516 * protect us against recursive calling from irq.
3518 asmlinkage
void __sched
preempt_schedule_irq(void)
3520 struct thread_info
*ti
= current_thread_info();
3521 #ifdef CONFIG_PREEMPT_BKL
3522 struct task_struct
*task
= current
;
3523 int saved_lock_depth
;
3525 /* Catch callers which need to be fixed */
3526 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3529 add_preempt_count(PREEMPT_ACTIVE
);
3531 * We keep the big kernel semaphore locked, but we
3532 * clear ->lock_depth so that schedule() doesnt
3533 * auto-release the semaphore:
3535 #ifdef CONFIG_PREEMPT_BKL
3536 saved_lock_depth
= task
->lock_depth
;
3537 task
->lock_depth
= -1;
3541 local_irq_disable();
3542 #ifdef CONFIG_PREEMPT_BKL
3543 task
->lock_depth
= saved_lock_depth
;
3545 sub_preempt_count(PREEMPT_ACTIVE
);
3547 /* we could miss a preemption opportunity between schedule and now */
3549 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3553 #endif /* CONFIG_PREEMPT */
3555 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3558 return try_to_wake_up(curr
->private, mode
, sync
);
3560 EXPORT_SYMBOL(default_wake_function
);
3563 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3564 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3565 * number) then we wake all the non-exclusive tasks and one exclusive task.
3567 * There are circumstances in which we can try to wake a task which has already
3568 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3569 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3571 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3572 int nr_exclusive
, int sync
, void *key
)
3574 wait_queue_t
*curr
, *next
;
3576 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3577 unsigned flags
= curr
->flags
;
3579 if (curr
->func(curr
, mode
, sync
, key
) &&
3580 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3586 * __wake_up - wake up threads blocked on a waitqueue.
3588 * @mode: which threads
3589 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3590 * @key: is directly passed to the wakeup function
3592 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3593 int nr_exclusive
, void *key
)
3595 unsigned long flags
;
3597 spin_lock_irqsave(&q
->lock
, flags
);
3598 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3599 spin_unlock_irqrestore(&q
->lock
, flags
);
3601 EXPORT_SYMBOL(__wake_up
);
3604 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3606 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3608 __wake_up_common(q
, mode
, 1, 0, NULL
);
3612 * __wake_up_sync - wake up threads blocked on a waitqueue.
3614 * @mode: which threads
3615 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3617 * The sync wakeup differs that the waker knows that it will schedule
3618 * away soon, so while the target thread will be woken up, it will not
3619 * be migrated to another CPU - ie. the two threads are 'synchronized'
3620 * with each other. This can prevent needless bouncing between CPUs.
3622 * On UP it can prevent extra preemption.
3625 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3627 unsigned long flags
;
3633 if (unlikely(!nr_exclusive
))
3636 spin_lock_irqsave(&q
->lock
, flags
);
3637 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3638 spin_unlock_irqrestore(&q
->lock
, flags
);
3640 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3642 void fastcall
complete(struct completion
*x
)
3644 unsigned long flags
;
3646 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3648 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3650 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3652 EXPORT_SYMBOL(complete
);
3654 void fastcall
complete_all(struct completion
*x
)
3656 unsigned long flags
;
3658 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3659 x
->done
+= UINT_MAX
/2;
3660 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3662 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3664 EXPORT_SYMBOL(complete_all
);
3666 void fastcall __sched
wait_for_completion(struct completion
*x
)
3670 spin_lock_irq(&x
->wait
.lock
);
3672 DECLARE_WAITQUEUE(wait
, current
);
3674 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3675 __add_wait_queue_tail(&x
->wait
, &wait
);
3677 __set_current_state(TASK_UNINTERRUPTIBLE
);
3678 spin_unlock_irq(&x
->wait
.lock
);
3680 spin_lock_irq(&x
->wait
.lock
);
3682 __remove_wait_queue(&x
->wait
, &wait
);
3685 spin_unlock_irq(&x
->wait
.lock
);
3687 EXPORT_SYMBOL(wait_for_completion
);
3689 unsigned long fastcall __sched
3690 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3694 spin_lock_irq(&x
->wait
.lock
);
3696 DECLARE_WAITQUEUE(wait
, current
);
3698 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3699 __add_wait_queue_tail(&x
->wait
, &wait
);
3701 __set_current_state(TASK_UNINTERRUPTIBLE
);
3702 spin_unlock_irq(&x
->wait
.lock
);
3703 timeout
= schedule_timeout(timeout
);
3704 spin_lock_irq(&x
->wait
.lock
);
3706 __remove_wait_queue(&x
->wait
, &wait
);
3710 __remove_wait_queue(&x
->wait
, &wait
);
3714 spin_unlock_irq(&x
->wait
.lock
);
3717 EXPORT_SYMBOL(wait_for_completion_timeout
);
3719 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3725 spin_lock_irq(&x
->wait
.lock
);
3727 DECLARE_WAITQUEUE(wait
, current
);
3729 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3730 __add_wait_queue_tail(&x
->wait
, &wait
);
3732 if (signal_pending(current
)) {
3734 __remove_wait_queue(&x
->wait
, &wait
);
3737 __set_current_state(TASK_INTERRUPTIBLE
);
3738 spin_unlock_irq(&x
->wait
.lock
);
3740 spin_lock_irq(&x
->wait
.lock
);
3742 __remove_wait_queue(&x
->wait
, &wait
);
3746 spin_unlock_irq(&x
->wait
.lock
);
3750 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3752 unsigned long fastcall __sched
3753 wait_for_completion_interruptible_timeout(struct completion
*x
,
3754 unsigned long timeout
)
3758 spin_lock_irq(&x
->wait
.lock
);
3760 DECLARE_WAITQUEUE(wait
, current
);
3762 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3763 __add_wait_queue_tail(&x
->wait
, &wait
);
3765 if (signal_pending(current
)) {
3766 timeout
= -ERESTARTSYS
;
3767 __remove_wait_queue(&x
->wait
, &wait
);
3770 __set_current_state(TASK_INTERRUPTIBLE
);
3771 spin_unlock_irq(&x
->wait
.lock
);
3772 timeout
= schedule_timeout(timeout
);
3773 spin_lock_irq(&x
->wait
.lock
);
3775 __remove_wait_queue(&x
->wait
, &wait
);
3779 __remove_wait_queue(&x
->wait
, &wait
);
3783 spin_unlock_irq(&x
->wait
.lock
);
3786 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3789 sleep_on_head(wait_queue_head_t
*q
, wait_queue_t
*wait
, unsigned long *flags
)
3791 spin_lock_irqsave(&q
->lock
, *flags
);
3792 __add_wait_queue(q
, wait
);
3793 spin_unlock(&q
->lock
);
3797 sleep_on_tail(wait_queue_head_t
*q
, wait_queue_t
*wait
, unsigned long *flags
)
3799 spin_lock_irq(&q
->lock
);
3800 __remove_wait_queue(q
, wait
);
3801 spin_unlock_irqrestore(&q
->lock
, *flags
);
3804 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3806 unsigned long flags
;
3809 init_waitqueue_entry(&wait
, current
);
3811 current
->state
= TASK_INTERRUPTIBLE
;
3813 sleep_on_head(q
, &wait
, &flags
);
3815 sleep_on_tail(q
, &wait
, &flags
);
3817 EXPORT_SYMBOL(interruptible_sleep_on
);
3820 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3822 unsigned long flags
;
3825 init_waitqueue_entry(&wait
, current
);
3827 current
->state
= TASK_INTERRUPTIBLE
;
3829 sleep_on_head(q
, &wait
, &flags
);
3830 timeout
= schedule_timeout(timeout
);
3831 sleep_on_tail(q
, &wait
, &flags
);
3835 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3837 void __sched
sleep_on(wait_queue_head_t
*q
)
3839 unsigned long flags
;
3842 init_waitqueue_entry(&wait
, current
);
3844 current
->state
= TASK_UNINTERRUPTIBLE
;
3846 sleep_on_head(q
, &wait
, &flags
);
3848 sleep_on_tail(q
, &wait
, &flags
);
3850 EXPORT_SYMBOL(sleep_on
);
3852 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3854 unsigned long flags
;
3857 init_waitqueue_entry(&wait
, current
);
3859 current
->state
= TASK_UNINTERRUPTIBLE
;
3861 sleep_on_head(q
, &wait
, &flags
);
3862 timeout
= schedule_timeout(timeout
);
3863 sleep_on_tail(q
, &wait
, &flags
);
3867 EXPORT_SYMBOL(sleep_on_timeout
);
3869 #ifdef CONFIG_RT_MUTEXES
3872 * rt_mutex_setprio - set the current priority of a task
3874 * @prio: prio value (kernel-internal form)
3876 * This function changes the 'effective' priority of a task. It does
3877 * not touch ->normal_prio like __setscheduler().
3879 * Used by the rt_mutex code to implement priority inheritance logic.
3881 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3883 unsigned long flags
;
3887 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3889 rq
= task_rq_lock(p
, &flags
);
3890 update_rq_clock(rq
);
3893 on_rq
= p
->se
.on_rq
;
3895 dequeue_task(rq
, p
, 0);
3898 p
->sched_class
= &rt_sched_class
;
3900 p
->sched_class
= &fair_sched_class
;
3905 enqueue_task(rq
, p
, 0);
3907 * Reschedule if we are currently running on this runqueue and
3908 * our priority decreased, or if we are not currently running on
3909 * this runqueue and our priority is higher than the current's
3911 if (task_running(rq
, p
)) {
3912 if (p
->prio
> oldprio
)
3913 resched_task(rq
->curr
);
3915 check_preempt_curr(rq
, p
);
3918 task_rq_unlock(rq
, &flags
);
3923 void set_user_nice(struct task_struct
*p
, long nice
)
3925 int old_prio
, delta
, on_rq
;
3926 unsigned long flags
;
3929 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3932 * We have to be careful, if called from sys_setpriority(),
3933 * the task might be in the middle of scheduling on another CPU.
3935 rq
= task_rq_lock(p
, &flags
);
3936 update_rq_clock(rq
);
3938 * The RT priorities are set via sched_setscheduler(), but we still
3939 * allow the 'normal' nice value to be set - but as expected
3940 * it wont have any effect on scheduling until the task is
3941 * SCHED_FIFO/SCHED_RR:
3943 if (task_has_rt_policy(p
)) {
3944 p
->static_prio
= NICE_TO_PRIO(nice
);
3947 on_rq
= p
->se
.on_rq
;
3949 dequeue_task(rq
, p
, 0);
3953 p
->static_prio
= NICE_TO_PRIO(nice
);
3956 p
->prio
= effective_prio(p
);
3957 delta
= p
->prio
- old_prio
;
3960 enqueue_task(rq
, p
, 0);
3963 * If the task increased its priority or is running and
3964 * lowered its priority, then reschedule its CPU:
3966 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3967 resched_task(rq
->curr
);
3970 task_rq_unlock(rq
, &flags
);
3972 EXPORT_SYMBOL(set_user_nice
);
3975 * can_nice - check if a task can reduce its nice value
3979 int can_nice(const struct task_struct
*p
, const int nice
)
3981 /* convert nice value [19,-20] to rlimit style value [1,40] */
3982 int nice_rlim
= 20 - nice
;
3984 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3985 capable(CAP_SYS_NICE
));
3988 #ifdef __ARCH_WANT_SYS_NICE
3991 * sys_nice - change the priority of the current process.
3992 * @increment: priority increment
3994 * sys_setpriority is a more generic, but much slower function that
3995 * does similar things.
3997 asmlinkage
long sys_nice(int increment
)
4002 * Setpriority might change our priority at the same moment.
4003 * We don't have to worry. Conceptually one call occurs first
4004 * and we have a single winner.
4006 if (increment
< -40)
4011 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4017 if (increment
< 0 && !can_nice(current
, nice
))
4020 retval
= security_task_setnice(current
, nice
);
4024 set_user_nice(current
, nice
);
4031 * task_prio - return the priority value of a given task.
4032 * @p: the task in question.
4034 * This is the priority value as seen by users in /proc.
4035 * RT tasks are offset by -200. Normal tasks are centered
4036 * around 0, value goes from -16 to +15.
4038 int task_prio(const struct task_struct
*p
)
4040 return p
->prio
- MAX_RT_PRIO
;
4044 * task_nice - return the nice value of a given task.
4045 * @p: the task in question.
4047 int task_nice(const struct task_struct
*p
)
4049 return TASK_NICE(p
);
4051 EXPORT_SYMBOL_GPL(task_nice
);
4054 * idle_cpu - is a given cpu idle currently?
4055 * @cpu: the processor in question.
4057 int idle_cpu(int cpu
)
4059 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4063 * idle_task - return the idle task for a given cpu.
4064 * @cpu: the processor in question.
4066 struct task_struct
*idle_task(int cpu
)
4068 return cpu_rq(cpu
)->idle
;
4072 * find_process_by_pid - find a process with a matching PID value.
4073 * @pid: the pid in question.
4075 static inline struct task_struct
*find_process_by_pid(pid_t pid
)
4077 return pid
? find_task_by_pid(pid
) : current
;
4080 /* Actually do priority change: must hold rq lock. */
4082 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4084 BUG_ON(p
->se
.on_rq
);
4087 switch (p
->policy
) {
4091 p
->sched_class
= &fair_sched_class
;
4095 p
->sched_class
= &rt_sched_class
;
4099 p
->rt_priority
= prio
;
4100 p
->normal_prio
= normal_prio(p
);
4101 /* we are holding p->pi_lock already */
4102 p
->prio
= rt_mutex_getprio(p
);
4107 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4108 * @p: the task in question.
4109 * @policy: new policy.
4110 * @param: structure containing the new RT priority.
4112 * NOTE that the task may be already dead.
4114 int sched_setscheduler(struct task_struct
*p
, int policy
,
4115 struct sched_param
*param
)
4117 int retval
, oldprio
, oldpolicy
= -1, on_rq
;
4118 unsigned long flags
;
4121 /* may grab non-irq protected spin_locks */
4122 BUG_ON(in_interrupt());
4124 /* double check policy once rq lock held */
4126 policy
= oldpolicy
= p
->policy
;
4127 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4128 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4129 policy
!= SCHED_IDLE
)
4132 * Valid priorities for SCHED_FIFO and SCHED_RR are
4133 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4134 * SCHED_BATCH and SCHED_IDLE is 0.
4136 if (param
->sched_priority
< 0 ||
4137 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4138 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4140 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4144 * Allow unprivileged RT tasks to decrease priority:
4146 if (!capable(CAP_SYS_NICE
)) {
4147 if (rt_policy(policy
)) {
4148 unsigned long rlim_rtprio
;
4150 if (!lock_task_sighand(p
, &flags
))
4152 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4153 unlock_task_sighand(p
, &flags
);
4155 /* can't set/change the rt policy */
4156 if (policy
!= p
->policy
&& !rlim_rtprio
)
4159 /* can't increase priority */
4160 if (param
->sched_priority
> p
->rt_priority
&&
4161 param
->sched_priority
> rlim_rtprio
)
4165 * Like positive nice levels, dont allow tasks to
4166 * move out of SCHED_IDLE either:
4168 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4171 /* can't change other user's priorities */
4172 if ((current
->euid
!= p
->euid
) &&
4173 (current
->euid
!= p
->uid
))
4177 retval
= security_task_setscheduler(p
, policy
, param
);
4181 * make sure no PI-waiters arrive (or leave) while we are
4182 * changing the priority of the task:
4184 spin_lock_irqsave(&p
->pi_lock
, flags
);
4186 * To be able to change p->policy safely, the apropriate
4187 * runqueue lock must be held.
4189 rq
= __task_rq_lock(p
);
4190 /* recheck policy now with rq lock held */
4191 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4192 policy
= oldpolicy
= -1;
4193 __task_rq_unlock(rq
);
4194 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4197 update_rq_clock(rq
);
4198 on_rq
= p
->se
.on_rq
;
4200 deactivate_task(rq
, p
, 0);
4202 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4204 activate_task(rq
, p
, 0);
4206 * Reschedule if we are currently running on this runqueue and
4207 * our priority decreased, or if we are not currently running on
4208 * this runqueue and our priority is higher than the current's
4210 if (task_running(rq
, p
)) {
4211 if (p
->prio
> oldprio
)
4212 resched_task(rq
->curr
);
4214 check_preempt_curr(rq
, p
);
4217 __task_rq_unlock(rq
);
4218 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4220 rt_mutex_adjust_pi(p
);
4224 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4227 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4229 struct sched_param lparam
;
4230 struct task_struct
*p
;
4233 if (!param
|| pid
< 0)
4235 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4240 p
= find_process_by_pid(pid
);
4242 retval
= sched_setscheduler(p
, policy
, &lparam
);
4249 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4250 * @pid: the pid in question.
4251 * @policy: new policy.
4252 * @param: structure containing the new RT priority.
4254 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
4255 struct sched_param __user
*param
)
4257 /* negative values for policy are not valid */
4261 return do_sched_setscheduler(pid
, policy
, param
);
4265 * sys_sched_setparam - set/change the RT priority of a thread
4266 * @pid: the pid in question.
4267 * @param: structure containing the new RT priority.
4269 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4271 return do_sched_setscheduler(pid
, -1, param
);
4275 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4276 * @pid: the pid in question.
4278 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4280 struct task_struct
*p
;
4281 int retval
= -EINVAL
;
4287 read_lock(&tasklist_lock
);
4288 p
= find_process_by_pid(pid
);
4290 retval
= security_task_getscheduler(p
);
4294 read_unlock(&tasklist_lock
);
4301 * sys_sched_getscheduler - get the RT priority of a thread
4302 * @pid: the pid in question.
4303 * @param: structure containing the RT priority.
4305 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4307 struct sched_param lp
;
4308 struct task_struct
*p
;
4309 int retval
= -EINVAL
;
4311 if (!param
|| pid
< 0)
4314 read_lock(&tasklist_lock
);
4315 p
= find_process_by_pid(pid
);
4320 retval
= security_task_getscheduler(p
);
4324 lp
.sched_priority
= p
->rt_priority
;
4325 read_unlock(&tasklist_lock
);
4328 * This one might sleep, we cannot do it with a spinlock held ...
4330 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4336 read_unlock(&tasklist_lock
);
4340 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4342 cpumask_t cpus_allowed
;
4343 struct task_struct
*p
;
4346 mutex_lock(&sched_hotcpu_mutex
);
4347 read_lock(&tasklist_lock
);
4349 p
= find_process_by_pid(pid
);
4351 read_unlock(&tasklist_lock
);
4352 mutex_unlock(&sched_hotcpu_mutex
);
4357 * It is not safe to call set_cpus_allowed with the
4358 * tasklist_lock held. We will bump the task_struct's
4359 * usage count and then drop tasklist_lock.
4362 read_unlock(&tasklist_lock
);
4365 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4366 !capable(CAP_SYS_NICE
))
4369 retval
= security_task_setscheduler(p
, 0, NULL
);
4373 cpus_allowed
= cpuset_cpus_allowed(p
);
4374 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4375 retval
= set_cpus_allowed(p
, new_mask
);
4379 mutex_unlock(&sched_hotcpu_mutex
);
4383 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4384 cpumask_t
*new_mask
)
4386 if (len
< sizeof(cpumask_t
)) {
4387 memset(new_mask
, 0, sizeof(cpumask_t
));
4388 } else if (len
> sizeof(cpumask_t
)) {
4389 len
= sizeof(cpumask_t
);
4391 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4395 * sys_sched_setaffinity - set the cpu affinity of a process
4396 * @pid: pid of the process
4397 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4398 * @user_mask_ptr: user-space pointer to the new cpu mask
4400 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4401 unsigned long __user
*user_mask_ptr
)
4406 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4410 return sched_setaffinity(pid
, new_mask
);
4414 * Represents all cpu's present in the system
4415 * In systems capable of hotplug, this map could dynamically grow
4416 * as new cpu's are detected in the system via any platform specific
4417 * method, such as ACPI for e.g.
4420 cpumask_t cpu_present_map __read_mostly
;
4421 EXPORT_SYMBOL(cpu_present_map
);
4424 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4425 EXPORT_SYMBOL(cpu_online_map
);
4427 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4428 EXPORT_SYMBOL(cpu_possible_map
);
4431 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4433 struct task_struct
*p
;
4436 mutex_lock(&sched_hotcpu_mutex
);
4437 read_lock(&tasklist_lock
);
4440 p
= find_process_by_pid(pid
);
4444 retval
= security_task_getscheduler(p
);
4448 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4451 read_unlock(&tasklist_lock
);
4452 mutex_unlock(&sched_hotcpu_mutex
);
4458 * sys_sched_getaffinity - get the cpu affinity of a process
4459 * @pid: pid of the process
4460 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4461 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4463 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4464 unsigned long __user
*user_mask_ptr
)
4469 if (len
< sizeof(cpumask_t
))
4472 ret
= sched_getaffinity(pid
, &mask
);
4476 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4479 return sizeof(cpumask_t
);
4483 * sys_sched_yield - yield the current processor to other threads.
4485 * This function yields the current CPU to other tasks. If there are no
4486 * other threads running on this CPU then this function will return.
4488 asmlinkage
long sys_sched_yield(void)
4490 struct rq
*rq
= this_rq_lock();
4492 schedstat_inc(rq
, yld_cnt
);
4493 current
->sched_class
->yield_task(rq
, current
);
4496 * Since we are going to call schedule() anyway, there's
4497 * no need to preempt or enable interrupts:
4499 __release(rq
->lock
);
4500 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4501 _raw_spin_unlock(&rq
->lock
);
4502 preempt_enable_no_resched();
4509 static void __cond_resched(void)
4511 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4512 __might_sleep(__FILE__
, __LINE__
);
4515 * The BKS might be reacquired before we have dropped
4516 * PREEMPT_ACTIVE, which could trigger a second
4517 * cond_resched() call.
4520 add_preempt_count(PREEMPT_ACTIVE
);
4522 sub_preempt_count(PREEMPT_ACTIVE
);
4523 } while (need_resched());
4526 int __sched
cond_resched(void)
4528 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4529 system_state
== SYSTEM_RUNNING
) {
4535 EXPORT_SYMBOL(cond_resched
);
4538 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4539 * call schedule, and on return reacquire the lock.
4541 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4542 * operations here to prevent schedule() from being called twice (once via
4543 * spin_unlock(), once by hand).
4545 int cond_resched_lock(spinlock_t
*lock
)
4549 if (need_lockbreak(lock
)) {
4555 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4556 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4557 _raw_spin_unlock(lock
);
4558 preempt_enable_no_resched();
4565 EXPORT_SYMBOL(cond_resched_lock
);
4567 int __sched
cond_resched_softirq(void)
4569 BUG_ON(!in_softirq());
4571 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4579 EXPORT_SYMBOL(cond_resched_softirq
);
4582 * yield - yield the current processor to other threads.
4584 * This is a shortcut for kernel-space yielding - it marks the
4585 * thread runnable and calls sys_sched_yield().
4587 void __sched
yield(void)
4589 set_current_state(TASK_RUNNING
);
4592 EXPORT_SYMBOL(yield
);
4595 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4596 * that process accounting knows that this is a task in IO wait state.
4598 * But don't do that if it is a deliberate, throttling IO wait (this task
4599 * has set its backing_dev_info: the queue against which it should throttle)
4601 void __sched
io_schedule(void)
4603 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4605 delayacct_blkio_start();
4606 atomic_inc(&rq
->nr_iowait
);
4608 atomic_dec(&rq
->nr_iowait
);
4609 delayacct_blkio_end();
4611 EXPORT_SYMBOL(io_schedule
);
4613 long __sched
io_schedule_timeout(long timeout
)
4615 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4618 delayacct_blkio_start();
4619 atomic_inc(&rq
->nr_iowait
);
4620 ret
= schedule_timeout(timeout
);
4621 atomic_dec(&rq
->nr_iowait
);
4622 delayacct_blkio_end();
4627 * sys_sched_get_priority_max - return maximum RT priority.
4628 * @policy: scheduling class.
4630 * this syscall returns the maximum rt_priority that can be used
4631 * by a given scheduling class.
4633 asmlinkage
long sys_sched_get_priority_max(int policy
)
4640 ret
= MAX_USER_RT_PRIO
-1;
4652 * sys_sched_get_priority_min - return minimum RT priority.
4653 * @policy: scheduling class.
4655 * this syscall returns the minimum rt_priority that can be used
4656 * by a given scheduling class.
4658 asmlinkage
long sys_sched_get_priority_min(int policy
)
4676 * sys_sched_rr_get_interval - return the default timeslice of a process.
4677 * @pid: pid of the process.
4678 * @interval: userspace pointer to the timeslice value.
4680 * this syscall writes the default timeslice value of a given process
4681 * into the user-space timespec buffer. A value of '0' means infinity.
4684 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4686 struct task_struct
*p
;
4687 int retval
= -EINVAL
;
4694 read_lock(&tasklist_lock
);
4695 p
= find_process_by_pid(pid
);
4699 retval
= security_task_getscheduler(p
);
4703 jiffies_to_timespec(p
->policy
== SCHED_FIFO
?
4704 0 : static_prio_timeslice(p
->static_prio
), &t
);
4705 read_unlock(&tasklist_lock
);
4706 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4710 read_unlock(&tasklist_lock
);
4714 static const char stat_nam
[] = "RSDTtZX";
4716 static void show_task(struct task_struct
*p
)
4718 unsigned long free
= 0;
4721 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4722 printk("%-13.13s %c", p
->comm
,
4723 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4724 #if BITS_PER_LONG == 32
4725 if (state
== TASK_RUNNING
)
4726 printk(" running ");
4728 printk(" %08lx ", thread_saved_pc(p
));
4730 if (state
== TASK_RUNNING
)
4731 printk(" running task ");
4733 printk(" %016lx ", thread_saved_pc(p
));
4735 #ifdef CONFIG_DEBUG_STACK_USAGE
4737 unsigned long *n
= end_of_stack(p
);
4740 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4743 printk("%5lu %5d %6d\n", free
, p
->pid
, p
->parent
->pid
);
4745 if (state
!= TASK_RUNNING
)
4746 show_stack(p
, NULL
);
4749 void show_state_filter(unsigned long state_filter
)
4751 struct task_struct
*g
, *p
;
4753 #if BITS_PER_LONG == 32
4755 " task PC stack pid father\n");
4758 " task PC stack pid father\n");
4760 read_lock(&tasklist_lock
);
4761 do_each_thread(g
, p
) {
4763 * reset the NMI-timeout, listing all files on a slow
4764 * console might take alot of time:
4766 touch_nmi_watchdog();
4767 if (!state_filter
|| (p
->state
& state_filter
))
4769 } while_each_thread(g
, p
);
4771 touch_all_softlockup_watchdogs();
4773 #ifdef CONFIG_SCHED_DEBUG
4774 sysrq_sched_debug_show();
4776 read_unlock(&tasklist_lock
);
4778 * Only show locks if all tasks are dumped:
4780 if (state_filter
== -1)
4781 debug_show_all_locks();
4784 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4786 idle
->sched_class
= &idle_sched_class
;
4790 * init_idle - set up an idle thread for a given CPU
4791 * @idle: task in question
4792 * @cpu: cpu the idle task belongs to
4794 * NOTE: this function does not set the idle thread's NEED_RESCHED
4795 * flag, to make booting more robust.
4797 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4799 struct rq
*rq
= cpu_rq(cpu
);
4800 unsigned long flags
;
4803 idle
->se
.exec_start
= sched_clock();
4805 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4806 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4807 __set_task_cpu(idle
, cpu
);
4809 spin_lock_irqsave(&rq
->lock
, flags
);
4810 rq
->curr
= rq
->idle
= idle
;
4811 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4814 spin_unlock_irqrestore(&rq
->lock
, flags
);
4816 /* Set the preempt count _outside_ the spinlocks! */
4817 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4818 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4820 task_thread_info(idle
)->preempt_count
= 0;
4823 * The idle tasks have their own, simple scheduling class:
4825 idle
->sched_class
= &idle_sched_class
;
4829 * In a system that switches off the HZ timer nohz_cpu_mask
4830 * indicates which cpus entered this state. This is used
4831 * in the rcu update to wait only for active cpus. For system
4832 * which do not switch off the HZ timer nohz_cpu_mask should
4833 * always be CPU_MASK_NONE.
4835 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4839 * This is how migration works:
4841 * 1) we queue a struct migration_req structure in the source CPU's
4842 * runqueue and wake up that CPU's migration thread.
4843 * 2) we down() the locked semaphore => thread blocks.
4844 * 3) migration thread wakes up (implicitly it forces the migrated
4845 * thread off the CPU)
4846 * 4) it gets the migration request and checks whether the migrated
4847 * task is still in the wrong runqueue.
4848 * 5) if it's in the wrong runqueue then the migration thread removes
4849 * it and puts it into the right queue.
4850 * 6) migration thread up()s the semaphore.
4851 * 7) we wake up and the migration is done.
4855 * Change a given task's CPU affinity. Migrate the thread to a
4856 * proper CPU and schedule it away if the CPU it's executing on
4857 * is removed from the allowed bitmask.
4859 * NOTE: the caller must have a valid reference to the task, the
4860 * task must not exit() & deallocate itself prematurely. The
4861 * call is not atomic; no spinlocks may be held.
4863 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
4865 struct migration_req req
;
4866 unsigned long flags
;
4870 rq
= task_rq_lock(p
, &flags
);
4871 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4876 p
->cpus_allowed
= new_mask
;
4877 /* Can the task run on the task's current CPU? If so, we're done */
4878 if (cpu_isset(task_cpu(p
), new_mask
))
4881 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4882 /* Need help from migration thread: drop lock and wait. */
4883 task_rq_unlock(rq
, &flags
);
4884 wake_up_process(rq
->migration_thread
);
4885 wait_for_completion(&req
.done
);
4886 tlb_migrate_finish(p
->mm
);
4890 task_rq_unlock(rq
, &flags
);
4894 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4897 * Move (not current) task off this cpu, onto dest cpu. We're doing
4898 * this because either it can't run here any more (set_cpus_allowed()
4899 * away from this CPU, or CPU going down), or because we're
4900 * attempting to rebalance this task on exec (sched_exec).
4902 * So we race with normal scheduler movements, but that's OK, as long
4903 * as the task is no longer on this CPU.
4905 * Returns non-zero if task was successfully migrated.
4907 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4909 struct rq
*rq_dest
, *rq_src
;
4912 if (unlikely(cpu_is_offline(dest_cpu
)))
4915 rq_src
= cpu_rq(src_cpu
);
4916 rq_dest
= cpu_rq(dest_cpu
);
4918 double_rq_lock(rq_src
, rq_dest
);
4919 /* Already moved. */
4920 if (task_cpu(p
) != src_cpu
)
4922 /* Affinity changed (again). */
4923 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4926 on_rq
= p
->se
.on_rq
;
4928 deactivate_task(rq_src
, p
, 0);
4930 set_task_cpu(p
, dest_cpu
);
4932 activate_task(rq_dest
, p
, 0);
4933 check_preempt_curr(rq_dest
, p
);
4937 double_rq_unlock(rq_src
, rq_dest
);
4942 * migration_thread - this is a highprio system thread that performs
4943 * thread migration by bumping thread off CPU then 'pushing' onto
4946 static int migration_thread(void *data
)
4948 int cpu
= (long)data
;
4952 BUG_ON(rq
->migration_thread
!= current
);
4954 set_current_state(TASK_INTERRUPTIBLE
);
4955 while (!kthread_should_stop()) {
4956 struct migration_req
*req
;
4957 struct list_head
*head
;
4959 spin_lock_irq(&rq
->lock
);
4961 if (cpu_is_offline(cpu
)) {
4962 spin_unlock_irq(&rq
->lock
);
4966 if (rq
->active_balance
) {
4967 active_load_balance(rq
, cpu
);
4968 rq
->active_balance
= 0;
4971 head
= &rq
->migration_queue
;
4973 if (list_empty(head
)) {
4974 spin_unlock_irq(&rq
->lock
);
4976 set_current_state(TASK_INTERRUPTIBLE
);
4979 req
= list_entry(head
->next
, struct migration_req
, list
);
4980 list_del_init(head
->next
);
4982 spin_unlock(&rq
->lock
);
4983 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4986 complete(&req
->done
);
4988 __set_current_state(TASK_RUNNING
);
4992 /* Wait for kthread_stop */
4993 set_current_state(TASK_INTERRUPTIBLE
);
4994 while (!kthread_should_stop()) {
4996 set_current_state(TASK_INTERRUPTIBLE
);
4998 __set_current_state(TASK_RUNNING
);
5002 #ifdef CONFIG_HOTPLUG_CPU
5004 * Figure out where task on dead CPU should go, use force if neccessary.
5005 * NOTE: interrupts should be disabled by the caller
5007 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5009 unsigned long flags
;
5016 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5017 cpus_and(mask
, mask
, p
->cpus_allowed
);
5018 dest_cpu
= any_online_cpu(mask
);
5020 /* On any allowed CPU? */
5021 if (dest_cpu
== NR_CPUS
)
5022 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5024 /* No more Mr. Nice Guy. */
5025 if (dest_cpu
== NR_CPUS
) {
5026 rq
= task_rq_lock(p
, &flags
);
5027 cpus_setall(p
->cpus_allowed
);
5028 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5029 task_rq_unlock(rq
, &flags
);
5032 * Don't tell them about moving exiting tasks or
5033 * kernel threads (both mm NULL), since they never
5036 if (p
->mm
&& printk_ratelimit())
5037 printk(KERN_INFO
"process %d (%s) no "
5038 "longer affine to cpu%d\n",
5039 p
->pid
, p
->comm
, dead_cpu
);
5041 if (!__migrate_task(p
, dead_cpu
, dest_cpu
))
5046 * While a dead CPU has no uninterruptible tasks queued at this point,
5047 * it might still have a nonzero ->nr_uninterruptible counter, because
5048 * for performance reasons the counter is not stricly tracking tasks to
5049 * their home CPUs. So we just add the counter to another CPU's counter,
5050 * to keep the global sum constant after CPU-down:
5052 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5054 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5055 unsigned long flags
;
5057 local_irq_save(flags
);
5058 double_rq_lock(rq_src
, rq_dest
);
5059 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5060 rq_src
->nr_uninterruptible
= 0;
5061 double_rq_unlock(rq_src
, rq_dest
);
5062 local_irq_restore(flags
);
5065 /* Run through task list and migrate tasks from the dead cpu. */
5066 static void migrate_live_tasks(int src_cpu
)
5068 struct task_struct
*p
, *t
;
5070 write_lock_irq(&tasklist_lock
);
5072 do_each_thread(t
, p
) {
5076 if (task_cpu(p
) == src_cpu
)
5077 move_task_off_dead_cpu(src_cpu
, p
);
5078 } while_each_thread(t
, p
);
5080 write_unlock_irq(&tasklist_lock
);
5084 * Schedules idle task to be the next runnable task on current CPU.
5085 * It does so by boosting its priority to highest possible and adding it to
5086 * the _front_ of the runqueue. Used by CPU offline code.
5088 void sched_idle_next(void)
5090 int this_cpu
= smp_processor_id();
5091 struct rq
*rq
= cpu_rq(this_cpu
);
5092 struct task_struct
*p
= rq
->idle
;
5093 unsigned long flags
;
5095 /* cpu has to be offline */
5096 BUG_ON(cpu_online(this_cpu
));
5099 * Strictly not necessary since rest of the CPUs are stopped by now
5100 * and interrupts disabled on the current cpu.
5102 spin_lock_irqsave(&rq
->lock
, flags
);
5104 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5106 /* Add idle task to the _front_ of its priority queue: */
5107 activate_idle_task(p
, rq
);
5109 spin_unlock_irqrestore(&rq
->lock
, flags
);
5113 * Ensures that the idle task is using init_mm right before its cpu goes
5116 void idle_task_exit(void)
5118 struct mm_struct
*mm
= current
->active_mm
;
5120 BUG_ON(cpu_online(smp_processor_id()));
5123 switch_mm(mm
, &init_mm
, current
);
5127 /* called under rq->lock with disabled interrupts */
5128 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5130 struct rq
*rq
= cpu_rq(dead_cpu
);
5132 /* Must be exiting, otherwise would be on tasklist. */
5133 BUG_ON(p
->exit_state
!= EXIT_ZOMBIE
&& p
->exit_state
!= EXIT_DEAD
);
5135 /* Cannot have done final schedule yet: would have vanished. */
5136 BUG_ON(p
->state
== TASK_DEAD
);
5141 * Drop lock around migration; if someone else moves it,
5142 * that's OK. No task can be added to this CPU, so iteration is
5144 * NOTE: interrupts should be left disabled --dev@
5146 spin_unlock(&rq
->lock
);
5147 move_task_off_dead_cpu(dead_cpu
, p
);
5148 spin_lock(&rq
->lock
);
5153 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5154 static void migrate_dead_tasks(unsigned int dead_cpu
)
5156 struct rq
*rq
= cpu_rq(dead_cpu
);
5157 struct task_struct
*next
;
5160 if (!rq
->nr_running
)
5162 update_rq_clock(rq
);
5163 next
= pick_next_task(rq
, rq
->curr
);
5166 migrate_dead(dead_cpu
, next
);
5170 #endif /* CONFIG_HOTPLUG_CPU */
5172 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5174 static struct ctl_table sd_ctl_dir
[] = {
5176 .procname
= "sched_domain",
5182 static struct ctl_table sd_ctl_root
[] = {
5184 .ctl_name
= CTL_KERN
,
5185 .procname
= "kernel",
5187 .child
= sd_ctl_dir
,
5192 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5194 struct ctl_table
*entry
=
5195 kmalloc(n
* sizeof(struct ctl_table
), GFP_KERNEL
);
5198 memset(entry
, 0, n
* sizeof(struct ctl_table
));
5204 set_table_entry(struct ctl_table
*entry
,
5205 const char *procname
, void *data
, int maxlen
,
5206 mode_t mode
, proc_handler
*proc_handler
)
5208 entry
->procname
= procname
;
5210 entry
->maxlen
= maxlen
;
5212 entry
->proc_handler
= proc_handler
;
5215 static struct ctl_table
*
5216 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5218 struct ctl_table
*table
= sd_alloc_ctl_entry(14);
5220 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5221 sizeof(long), 0644, proc_doulongvec_minmax
);
5222 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5223 sizeof(long), 0644, proc_doulongvec_minmax
);
5224 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5225 sizeof(int), 0644, proc_dointvec_minmax
);
5226 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5227 sizeof(int), 0644, proc_dointvec_minmax
);
5228 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5229 sizeof(int), 0644, proc_dointvec_minmax
);
5230 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5231 sizeof(int), 0644, proc_dointvec_minmax
);
5232 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5233 sizeof(int), 0644, proc_dointvec_minmax
);
5234 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5235 sizeof(int), 0644, proc_dointvec_minmax
);
5236 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5237 sizeof(int), 0644, proc_dointvec_minmax
);
5238 set_table_entry(&table
[10], "cache_nice_tries",
5239 &sd
->cache_nice_tries
,
5240 sizeof(int), 0644, proc_dointvec_minmax
);
5241 set_table_entry(&table
[12], "flags", &sd
->flags
,
5242 sizeof(int), 0644, proc_dointvec_minmax
);
5247 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5249 struct ctl_table
*entry
, *table
;
5250 struct sched_domain
*sd
;
5251 int domain_num
= 0, i
;
5254 for_each_domain(cpu
, sd
)
5256 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5259 for_each_domain(cpu
, sd
) {
5260 snprintf(buf
, 32, "domain%d", i
);
5261 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5263 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5270 static struct ctl_table_header
*sd_sysctl_header
;
5271 static void init_sched_domain_sysctl(void)
5273 int i
, cpu_num
= num_online_cpus();
5274 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5277 sd_ctl_dir
[0].child
= entry
;
5279 for (i
= 0; i
< cpu_num
; i
++, entry
++) {
5280 snprintf(buf
, 32, "cpu%d", i
);
5281 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5283 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5285 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5288 static void init_sched_domain_sysctl(void)
5294 * migration_call - callback that gets triggered when a CPU is added.
5295 * Here we can start up the necessary migration thread for the new CPU.
5297 static int __cpuinit
5298 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5300 struct task_struct
*p
;
5301 int cpu
= (long)hcpu
;
5302 unsigned long flags
;
5306 case CPU_LOCK_ACQUIRE
:
5307 mutex_lock(&sched_hotcpu_mutex
);
5310 case CPU_UP_PREPARE
:
5311 case CPU_UP_PREPARE_FROZEN
:
5312 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5315 kthread_bind(p
, cpu
);
5316 /* Must be high prio: stop_machine expects to yield to it. */
5317 rq
= task_rq_lock(p
, &flags
);
5318 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5319 task_rq_unlock(rq
, &flags
);
5320 cpu_rq(cpu
)->migration_thread
= p
;
5324 case CPU_ONLINE_FROZEN
:
5325 /* Strictly unneccessary, as first user will wake it. */
5326 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5329 #ifdef CONFIG_HOTPLUG_CPU
5330 case CPU_UP_CANCELED
:
5331 case CPU_UP_CANCELED_FROZEN
:
5332 if (!cpu_rq(cpu
)->migration_thread
)
5334 /* Unbind it from offline cpu so it can run. Fall thru. */
5335 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5336 any_online_cpu(cpu_online_map
));
5337 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5338 cpu_rq(cpu
)->migration_thread
= NULL
;
5342 case CPU_DEAD_FROZEN
:
5343 migrate_live_tasks(cpu
);
5345 kthread_stop(rq
->migration_thread
);
5346 rq
->migration_thread
= NULL
;
5347 /* Idle task back to normal (off runqueue, low prio) */
5348 rq
= task_rq_lock(rq
->idle
, &flags
);
5349 update_rq_clock(rq
);
5350 deactivate_task(rq
, rq
->idle
, 0);
5351 rq
->idle
->static_prio
= MAX_PRIO
;
5352 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5353 rq
->idle
->sched_class
= &idle_sched_class
;
5354 migrate_dead_tasks(cpu
);
5355 task_rq_unlock(rq
, &flags
);
5356 migrate_nr_uninterruptible(rq
);
5357 BUG_ON(rq
->nr_running
!= 0);
5359 /* No need to migrate the tasks: it was best-effort if
5360 * they didn't take sched_hotcpu_mutex. Just wake up
5361 * the requestors. */
5362 spin_lock_irq(&rq
->lock
);
5363 while (!list_empty(&rq
->migration_queue
)) {
5364 struct migration_req
*req
;
5366 req
= list_entry(rq
->migration_queue
.next
,
5367 struct migration_req
, list
);
5368 list_del_init(&req
->list
);
5369 complete(&req
->done
);
5371 spin_unlock_irq(&rq
->lock
);
5374 case CPU_LOCK_RELEASE
:
5375 mutex_unlock(&sched_hotcpu_mutex
);
5381 /* Register at highest priority so that task migration (migrate_all_tasks)
5382 * happens before everything else.
5384 static struct notifier_block __cpuinitdata migration_notifier
= {
5385 .notifier_call
= migration_call
,
5389 int __init
migration_init(void)
5391 void *cpu
= (void *)(long)smp_processor_id();
5394 /* Start one for the boot CPU: */
5395 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5396 BUG_ON(err
== NOTIFY_BAD
);
5397 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5398 register_cpu_notifier(&migration_notifier
);
5406 /* Number of possible processor ids */
5407 int nr_cpu_ids __read_mostly
= NR_CPUS
;
5408 EXPORT_SYMBOL(nr_cpu_ids
);
5410 #undef SCHED_DOMAIN_DEBUG
5411 #ifdef SCHED_DOMAIN_DEBUG
5412 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5417 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5421 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5426 struct sched_group
*group
= sd
->groups
;
5427 cpumask_t groupmask
;
5429 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5430 cpus_clear(groupmask
);
5433 for (i
= 0; i
< level
+ 1; i
++)
5435 printk("domain %d: ", level
);
5437 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5438 printk("does not load-balance\n");
5440 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5445 printk("span %s\n", str
);
5447 if (!cpu_isset(cpu
, sd
->span
))
5448 printk(KERN_ERR
"ERROR: domain->span does not contain "
5450 if (!cpu_isset(cpu
, group
->cpumask
))
5451 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5455 for (i
= 0; i
< level
+ 2; i
++)
5461 printk(KERN_ERR
"ERROR: group is NULL\n");
5465 if (!group
->__cpu_power
) {
5467 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5471 if (!cpus_weight(group
->cpumask
)) {
5473 printk(KERN_ERR
"ERROR: empty group\n");
5476 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5478 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5481 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5483 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5486 group
= group
->next
;
5487 } while (group
!= sd
->groups
);
5490 if (!cpus_equal(sd
->span
, groupmask
))
5491 printk(KERN_ERR
"ERROR: groups don't span "
5499 if (!cpus_subset(groupmask
, sd
->span
))
5500 printk(KERN_ERR
"ERROR: parent span is not a superset "
5501 "of domain->span\n");
5506 # define sched_domain_debug(sd, cpu) do { } while (0)
5509 static int sd_degenerate(struct sched_domain
*sd
)
5511 if (cpus_weight(sd
->span
) == 1)
5514 /* Following flags need at least 2 groups */
5515 if (sd
->flags
& (SD_LOAD_BALANCE
|
5516 SD_BALANCE_NEWIDLE
|
5520 SD_SHARE_PKG_RESOURCES
)) {
5521 if (sd
->groups
!= sd
->groups
->next
)
5525 /* Following flags don't use groups */
5526 if (sd
->flags
& (SD_WAKE_IDLE
|
5535 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5537 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5539 if (sd_degenerate(parent
))
5542 if (!cpus_equal(sd
->span
, parent
->span
))
5545 /* Does parent contain flags not in child? */
5546 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5547 if (cflags
& SD_WAKE_AFFINE
)
5548 pflags
&= ~SD_WAKE_BALANCE
;
5549 /* Flags needing groups don't count if only 1 group in parent */
5550 if (parent
->groups
== parent
->groups
->next
) {
5551 pflags
&= ~(SD_LOAD_BALANCE
|
5552 SD_BALANCE_NEWIDLE
|
5556 SD_SHARE_PKG_RESOURCES
);
5558 if (~cflags
& pflags
)
5565 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5566 * hold the hotplug lock.
5568 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5570 struct rq
*rq
= cpu_rq(cpu
);
5571 struct sched_domain
*tmp
;
5573 /* Remove the sched domains which do not contribute to scheduling. */
5574 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5575 struct sched_domain
*parent
= tmp
->parent
;
5578 if (sd_parent_degenerate(tmp
, parent
)) {
5579 tmp
->parent
= parent
->parent
;
5581 parent
->parent
->child
= tmp
;
5585 if (sd
&& sd_degenerate(sd
)) {
5591 sched_domain_debug(sd
, cpu
);
5593 rcu_assign_pointer(rq
->sd
, sd
);
5596 /* cpus with isolated domains */
5597 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5599 /* Setup the mask of cpus configured for isolated domains */
5600 static int __init
isolated_cpu_setup(char *str
)
5602 int ints
[NR_CPUS
], i
;
5604 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5605 cpus_clear(cpu_isolated_map
);
5606 for (i
= 1; i
<= ints
[0]; i
++)
5607 if (ints
[i
] < NR_CPUS
)
5608 cpu_set(ints
[i
], cpu_isolated_map
);
5612 __setup ("isolcpus=", isolated_cpu_setup
);
5615 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5616 * to a function which identifies what group(along with sched group) a CPU
5617 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5618 * (due to the fact that we keep track of groups covered with a cpumask_t).
5620 * init_sched_build_groups will build a circular linked list of the groups
5621 * covered by the given span, and will set each group's ->cpumask correctly,
5622 * and ->cpu_power to 0.
5625 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5626 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5627 struct sched_group
**sg
))
5629 struct sched_group
*first
= NULL
, *last
= NULL
;
5630 cpumask_t covered
= CPU_MASK_NONE
;
5633 for_each_cpu_mask(i
, span
) {
5634 struct sched_group
*sg
;
5635 int group
= group_fn(i
, cpu_map
, &sg
);
5638 if (cpu_isset(i
, covered
))
5641 sg
->cpumask
= CPU_MASK_NONE
;
5642 sg
->__cpu_power
= 0;
5644 for_each_cpu_mask(j
, span
) {
5645 if (group_fn(j
, cpu_map
, NULL
) != group
)
5648 cpu_set(j
, covered
);
5649 cpu_set(j
, sg
->cpumask
);
5660 #define SD_NODES_PER_DOMAIN 16
5665 * find_next_best_node - find the next node to include in a sched_domain
5666 * @node: node whose sched_domain we're building
5667 * @used_nodes: nodes already in the sched_domain
5669 * Find the next node to include in a given scheduling domain. Simply
5670 * finds the closest node not already in the @used_nodes map.
5672 * Should use nodemask_t.
5674 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5676 int i
, n
, val
, min_val
, best_node
= 0;
5680 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5681 /* Start at @node */
5682 n
= (node
+ i
) % MAX_NUMNODES
;
5684 if (!nr_cpus_node(n
))
5687 /* Skip already used nodes */
5688 if (test_bit(n
, used_nodes
))
5691 /* Simple min distance search */
5692 val
= node_distance(node
, n
);
5694 if (val
< min_val
) {
5700 set_bit(best_node
, used_nodes
);
5705 * sched_domain_node_span - get a cpumask for a node's sched_domain
5706 * @node: node whose cpumask we're constructing
5707 * @size: number of nodes to include in this span
5709 * Given a node, construct a good cpumask for its sched_domain to span. It
5710 * should be one that prevents unnecessary balancing, but also spreads tasks
5713 static cpumask_t
sched_domain_node_span(int node
)
5715 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5716 cpumask_t span
, nodemask
;
5720 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5722 nodemask
= node_to_cpumask(node
);
5723 cpus_or(span
, span
, nodemask
);
5724 set_bit(node
, used_nodes
);
5726 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5727 int next_node
= find_next_best_node(node
, used_nodes
);
5729 nodemask
= node_to_cpumask(next_node
);
5730 cpus_or(span
, span
, nodemask
);
5737 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
5740 * SMT sched-domains:
5742 #ifdef CONFIG_SCHED_SMT
5743 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5744 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
5746 static int cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
,
5747 struct sched_group
**sg
)
5750 *sg
= &per_cpu(sched_group_cpus
, cpu
);
5756 * multi-core sched-domains:
5758 #ifdef CONFIG_SCHED_MC
5759 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
5760 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
5763 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
5764 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
5765 struct sched_group
**sg
)
5768 cpumask_t mask
= cpu_sibling_map
[cpu
];
5769 cpus_and(mask
, mask
, *cpu_map
);
5770 group
= first_cpu(mask
);
5772 *sg
= &per_cpu(sched_group_core
, group
);
5775 #elif defined(CONFIG_SCHED_MC)
5776 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
5777 struct sched_group
**sg
)
5780 *sg
= &per_cpu(sched_group_core
, cpu
);
5785 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5786 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
5788 static int cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
,
5789 struct sched_group
**sg
)
5792 #ifdef CONFIG_SCHED_MC
5793 cpumask_t mask
= cpu_coregroup_map(cpu
);
5794 cpus_and(mask
, mask
, *cpu_map
);
5795 group
= first_cpu(mask
);
5796 #elif defined(CONFIG_SCHED_SMT)
5797 cpumask_t mask
= cpu_sibling_map
[cpu
];
5798 cpus_and(mask
, mask
, *cpu_map
);
5799 group
= first_cpu(mask
);
5804 *sg
= &per_cpu(sched_group_phys
, group
);
5810 * The init_sched_build_groups can't handle what we want to do with node
5811 * groups, so roll our own. Now each node has its own list of groups which
5812 * gets dynamically allocated.
5814 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5815 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5817 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5818 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
5820 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
5821 struct sched_group
**sg
)
5823 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
5826 cpus_and(nodemask
, nodemask
, *cpu_map
);
5827 group
= first_cpu(nodemask
);
5830 *sg
= &per_cpu(sched_group_allnodes
, group
);
5834 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
5836 struct sched_group
*sg
= group_head
;
5842 for_each_cpu_mask(j
, sg
->cpumask
) {
5843 struct sched_domain
*sd
;
5845 sd
= &per_cpu(phys_domains
, j
);
5846 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5848 * Only add "power" once for each
5854 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
5857 if (sg
!= group_head
)
5863 /* Free memory allocated for various sched_group structures */
5864 static void free_sched_groups(const cpumask_t
*cpu_map
)
5868 for_each_cpu_mask(cpu
, *cpu_map
) {
5869 struct sched_group
**sched_group_nodes
5870 = sched_group_nodes_bycpu
[cpu
];
5872 if (!sched_group_nodes
)
5875 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5876 cpumask_t nodemask
= node_to_cpumask(i
);
5877 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5879 cpus_and(nodemask
, nodemask
, *cpu_map
);
5880 if (cpus_empty(nodemask
))
5890 if (oldsg
!= sched_group_nodes
[i
])
5893 kfree(sched_group_nodes
);
5894 sched_group_nodes_bycpu
[cpu
] = NULL
;
5898 static void free_sched_groups(const cpumask_t
*cpu_map
)
5904 * Initialize sched groups cpu_power.
5906 * cpu_power indicates the capacity of sched group, which is used while
5907 * distributing the load between different sched groups in a sched domain.
5908 * Typically cpu_power for all the groups in a sched domain will be same unless
5909 * there are asymmetries in the topology. If there are asymmetries, group
5910 * having more cpu_power will pickup more load compared to the group having
5913 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
5914 * the maximum number of tasks a group can handle in the presence of other idle
5915 * or lightly loaded groups in the same sched domain.
5917 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5919 struct sched_domain
*child
;
5920 struct sched_group
*group
;
5922 WARN_ON(!sd
|| !sd
->groups
);
5924 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
5929 sd
->groups
->__cpu_power
= 0;
5932 * For perf policy, if the groups in child domain share resources
5933 * (for example cores sharing some portions of the cache hierarchy
5934 * or SMT), then set this domain groups cpu_power such that each group
5935 * can handle only one task, when there are other idle groups in the
5936 * same sched domain.
5938 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
5940 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
5941 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
5946 * add cpu_power of each child group to this groups cpu_power
5948 group
= child
->groups
;
5950 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
5951 group
= group
->next
;
5952 } while (group
!= child
->groups
);
5956 * Build sched domains for a given set of cpus and attach the sched domains
5957 * to the individual cpus
5959 static int build_sched_domains(const cpumask_t
*cpu_map
)
5963 struct sched_group
**sched_group_nodes
= NULL
;
5964 int sd_allnodes
= 0;
5967 * Allocate the per-node list of sched groups
5969 sched_group_nodes
= kzalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
5971 if (!sched_group_nodes
) {
5972 printk(KERN_WARNING
"Can not alloc sched group node list\n");
5975 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
5979 * Set up domains for cpus specified by the cpu_map.
5981 for_each_cpu_mask(i
, *cpu_map
) {
5982 struct sched_domain
*sd
= NULL
, *p
;
5983 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
5985 cpus_and(nodemask
, nodemask
, *cpu_map
);
5988 if (cpus_weight(*cpu_map
) >
5989 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
5990 sd
= &per_cpu(allnodes_domains
, i
);
5991 *sd
= SD_ALLNODES_INIT
;
5992 sd
->span
= *cpu_map
;
5993 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
5999 sd
= &per_cpu(node_domains
, i
);
6001 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6005 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6009 sd
= &per_cpu(phys_domains
, i
);
6011 sd
->span
= nodemask
;
6015 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6017 #ifdef CONFIG_SCHED_MC
6019 sd
= &per_cpu(core_domains
, i
);
6021 sd
->span
= cpu_coregroup_map(i
);
6022 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6025 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6028 #ifdef CONFIG_SCHED_SMT
6030 sd
= &per_cpu(cpu_domains
, i
);
6031 *sd
= SD_SIBLING_INIT
;
6032 sd
->span
= cpu_sibling_map
[i
];
6033 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6036 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6040 #ifdef CONFIG_SCHED_SMT
6041 /* Set up CPU (sibling) groups */
6042 for_each_cpu_mask(i
, *cpu_map
) {
6043 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
6044 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6045 if (i
!= first_cpu(this_sibling_map
))
6048 init_sched_build_groups(this_sibling_map
, cpu_map
,
6053 #ifdef CONFIG_SCHED_MC
6054 /* Set up multi-core groups */
6055 for_each_cpu_mask(i
, *cpu_map
) {
6056 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6057 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6058 if (i
!= first_cpu(this_core_map
))
6060 init_sched_build_groups(this_core_map
, cpu_map
,
6061 &cpu_to_core_group
);
6065 /* Set up physical groups */
6066 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6067 cpumask_t nodemask
= node_to_cpumask(i
);
6069 cpus_and(nodemask
, nodemask
, *cpu_map
);
6070 if (cpus_empty(nodemask
))
6073 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6077 /* Set up node groups */
6079 init_sched_build_groups(*cpu_map
, cpu_map
,
6080 &cpu_to_allnodes_group
);
6082 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6083 /* Set up node groups */
6084 struct sched_group
*sg
, *prev
;
6085 cpumask_t nodemask
= node_to_cpumask(i
);
6086 cpumask_t domainspan
;
6087 cpumask_t covered
= CPU_MASK_NONE
;
6090 cpus_and(nodemask
, nodemask
, *cpu_map
);
6091 if (cpus_empty(nodemask
)) {
6092 sched_group_nodes
[i
] = NULL
;
6096 domainspan
= sched_domain_node_span(i
);
6097 cpus_and(domainspan
, domainspan
, *cpu_map
);
6099 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6101 printk(KERN_WARNING
"Can not alloc domain group for "
6105 sched_group_nodes
[i
] = sg
;
6106 for_each_cpu_mask(j
, nodemask
) {
6107 struct sched_domain
*sd
;
6109 sd
= &per_cpu(node_domains
, j
);
6112 sg
->__cpu_power
= 0;
6113 sg
->cpumask
= nodemask
;
6115 cpus_or(covered
, covered
, nodemask
);
6118 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6119 cpumask_t tmp
, notcovered
;
6120 int n
= (i
+ j
) % MAX_NUMNODES
;
6122 cpus_complement(notcovered
, covered
);
6123 cpus_and(tmp
, notcovered
, *cpu_map
);
6124 cpus_and(tmp
, tmp
, domainspan
);
6125 if (cpus_empty(tmp
))
6128 nodemask
= node_to_cpumask(n
);
6129 cpus_and(tmp
, tmp
, nodemask
);
6130 if (cpus_empty(tmp
))
6133 sg
= kmalloc_node(sizeof(struct sched_group
),
6137 "Can not alloc domain group for node %d\n", j
);
6140 sg
->__cpu_power
= 0;
6142 sg
->next
= prev
->next
;
6143 cpus_or(covered
, covered
, tmp
);
6150 /* Calculate CPU power for physical packages and nodes */
6151 #ifdef CONFIG_SCHED_SMT
6152 for_each_cpu_mask(i
, *cpu_map
) {
6153 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6155 init_sched_groups_power(i
, sd
);
6158 #ifdef CONFIG_SCHED_MC
6159 for_each_cpu_mask(i
, *cpu_map
) {
6160 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6162 init_sched_groups_power(i
, sd
);
6166 for_each_cpu_mask(i
, *cpu_map
) {
6167 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6169 init_sched_groups_power(i
, sd
);
6173 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6174 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6177 struct sched_group
*sg
;
6179 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6180 init_numa_sched_groups_power(sg
);
6184 /* Attach the domains */
6185 for_each_cpu_mask(i
, *cpu_map
) {
6186 struct sched_domain
*sd
;
6187 #ifdef CONFIG_SCHED_SMT
6188 sd
= &per_cpu(cpu_domains
, i
);
6189 #elif defined(CONFIG_SCHED_MC)
6190 sd
= &per_cpu(core_domains
, i
);
6192 sd
= &per_cpu(phys_domains
, i
);
6194 cpu_attach_domain(sd
, i
);
6201 free_sched_groups(cpu_map
);
6206 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6208 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6210 cpumask_t cpu_default_map
;
6214 * Setup mask for cpus without special case scheduling requirements.
6215 * For now this just excludes isolated cpus, but could be used to
6216 * exclude other special cases in the future.
6218 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
6220 err
= build_sched_domains(&cpu_default_map
);
6225 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6227 free_sched_groups(cpu_map
);
6231 * Detach sched domains from a group of cpus specified in cpu_map
6232 * These cpus will now be attached to the NULL domain
6234 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6238 for_each_cpu_mask(i
, *cpu_map
)
6239 cpu_attach_domain(NULL
, i
);
6240 synchronize_sched();
6241 arch_destroy_sched_domains(cpu_map
);
6245 * Partition sched domains as specified by the cpumasks below.
6246 * This attaches all cpus from the cpumasks to the NULL domain,
6247 * waits for a RCU quiescent period, recalculates sched
6248 * domain information and then attaches them back to the
6249 * correct sched domains
6250 * Call with hotplug lock held
6252 int partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
6254 cpumask_t change_map
;
6257 cpus_and(*partition1
, *partition1
, cpu_online_map
);
6258 cpus_and(*partition2
, *partition2
, cpu_online_map
);
6259 cpus_or(change_map
, *partition1
, *partition2
);
6261 /* Detach sched domains from all of the affected cpus */
6262 detach_destroy_domains(&change_map
);
6263 if (!cpus_empty(*partition1
))
6264 err
= build_sched_domains(partition1
);
6265 if (!err
&& !cpus_empty(*partition2
))
6266 err
= build_sched_domains(partition2
);
6271 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6272 static int arch_reinit_sched_domains(void)
6276 mutex_lock(&sched_hotcpu_mutex
);
6277 detach_destroy_domains(&cpu_online_map
);
6278 err
= arch_init_sched_domains(&cpu_online_map
);
6279 mutex_unlock(&sched_hotcpu_mutex
);
6284 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6288 if (buf
[0] != '0' && buf
[0] != '1')
6292 sched_smt_power_savings
= (buf
[0] == '1');
6294 sched_mc_power_savings
= (buf
[0] == '1');
6296 ret
= arch_reinit_sched_domains();
6298 return ret
? ret
: count
;
6301 #ifdef CONFIG_SCHED_MC
6302 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6304 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6306 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6307 const char *buf
, size_t count
)
6309 return sched_power_savings_store(buf
, count
, 0);
6311 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6312 sched_mc_power_savings_store
);
6315 #ifdef CONFIG_SCHED_SMT
6316 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6318 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6320 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6321 const char *buf
, size_t count
)
6323 return sched_power_savings_store(buf
, count
, 1);
6325 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6326 sched_smt_power_savings_store
);
6329 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6333 #ifdef CONFIG_SCHED_SMT
6335 err
= sysfs_create_file(&cls
->kset
.kobj
,
6336 &attr_sched_smt_power_savings
.attr
);
6338 #ifdef CONFIG_SCHED_MC
6339 if (!err
&& mc_capable())
6340 err
= sysfs_create_file(&cls
->kset
.kobj
,
6341 &attr_sched_mc_power_savings
.attr
);
6348 * Force a reinitialization of the sched domains hierarchy. The domains
6349 * and groups cannot be updated in place without racing with the balancing
6350 * code, so we temporarily attach all running cpus to the NULL domain
6351 * which will prevent rebalancing while the sched domains are recalculated.
6353 static int update_sched_domains(struct notifier_block
*nfb
,
6354 unsigned long action
, void *hcpu
)
6357 case CPU_UP_PREPARE
:
6358 case CPU_UP_PREPARE_FROZEN
:
6359 case CPU_DOWN_PREPARE
:
6360 case CPU_DOWN_PREPARE_FROZEN
:
6361 detach_destroy_domains(&cpu_online_map
);
6364 case CPU_UP_CANCELED
:
6365 case CPU_UP_CANCELED_FROZEN
:
6366 case CPU_DOWN_FAILED
:
6367 case CPU_DOWN_FAILED_FROZEN
:
6369 case CPU_ONLINE_FROZEN
:
6371 case CPU_DEAD_FROZEN
:
6373 * Fall through and re-initialise the domains.
6380 /* The hotplug lock is already held by cpu_up/cpu_down */
6381 arch_init_sched_domains(&cpu_online_map
);
6386 void __init
sched_init_smp(void)
6388 cpumask_t non_isolated_cpus
;
6390 mutex_lock(&sched_hotcpu_mutex
);
6391 arch_init_sched_domains(&cpu_online_map
);
6392 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6393 if (cpus_empty(non_isolated_cpus
))
6394 cpu_set(smp_processor_id(), non_isolated_cpus
);
6395 mutex_unlock(&sched_hotcpu_mutex
);
6396 /* XXX: Theoretical race here - CPU may be hotplugged now */
6397 hotcpu_notifier(update_sched_domains
, 0);
6399 init_sched_domain_sysctl();
6401 /* Move init over to a non-isolated CPU */
6402 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6406 void __init
sched_init_smp(void)
6409 #endif /* CONFIG_SMP */
6411 int in_sched_functions(unsigned long addr
)
6413 /* Linker adds these: start and end of __sched functions */
6414 extern char __sched_text_start
[], __sched_text_end
[];
6416 return in_lock_functions(addr
) ||
6417 (addr
>= (unsigned long)__sched_text_start
6418 && addr
< (unsigned long)__sched_text_end
);
6421 static inline void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
6423 cfs_rq
->tasks_timeline
= RB_ROOT
;
6424 cfs_rq
->fair_clock
= 1;
6425 #ifdef CONFIG_FAIR_GROUP_SCHED
6430 void __init
sched_init(void)
6432 int highest_cpu
= 0;
6436 * Link up the scheduling class hierarchy:
6438 rt_sched_class
.next
= &fair_sched_class
;
6439 fair_sched_class
.next
= &idle_sched_class
;
6440 idle_sched_class
.next
= NULL
;
6442 for_each_possible_cpu(i
) {
6443 struct rt_prio_array
*array
;
6447 spin_lock_init(&rq
->lock
);
6448 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6451 init_cfs_rq(&rq
->cfs
, rq
);
6452 #ifdef CONFIG_FAIR_GROUP_SCHED
6453 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6454 list_add(&rq
->cfs
.leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
6457 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6458 rq
->cpu_load
[j
] = 0;
6461 rq
->active_balance
= 0;
6462 rq
->next_balance
= jiffies
;
6465 rq
->migration_thread
= NULL
;
6466 INIT_LIST_HEAD(&rq
->migration_queue
);
6468 atomic_set(&rq
->nr_iowait
, 0);
6470 array
= &rq
->rt
.active
;
6471 for (j
= 0; j
< MAX_RT_PRIO
; j
++) {
6472 INIT_LIST_HEAD(array
->queue
+ j
);
6473 __clear_bit(j
, array
->bitmap
);
6476 /* delimiter for bitsearch: */
6477 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
6480 set_load_weight(&init_task
);
6482 #ifdef CONFIG_PREEMPT_NOTIFIERS
6483 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6487 nr_cpu_ids
= highest_cpu
+ 1;
6488 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6491 #ifdef CONFIG_RT_MUTEXES
6492 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6496 * The boot idle thread does lazy MMU switching as well:
6498 atomic_inc(&init_mm
.mm_count
);
6499 enter_lazy_tlb(&init_mm
, current
);
6502 * Make us the idle thread. Technically, schedule() should not be
6503 * called from this thread, however somewhere below it might be,
6504 * but because we are the idle thread, we just pick up running again
6505 * when this runqueue becomes "idle".
6507 init_idle(current
, smp_processor_id());
6509 * During early bootup we pretend to be a normal task:
6511 current
->sched_class
= &fair_sched_class
;
6514 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6515 void __might_sleep(char *file
, int line
)
6518 static unsigned long prev_jiffy
; /* ratelimiting */
6520 if ((in_atomic() || irqs_disabled()) &&
6521 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6522 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6524 prev_jiffy
= jiffies
;
6525 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6526 " context at %s:%d\n", file
, line
);
6527 printk("in_atomic():%d, irqs_disabled():%d\n",
6528 in_atomic(), irqs_disabled());
6529 debug_show_held_locks(current
);
6530 if (irqs_disabled())
6531 print_irqtrace_events(current
);
6536 EXPORT_SYMBOL(__might_sleep
);
6539 #ifdef CONFIG_MAGIC_SYSRQ
6540 void normalize_rt_tasks(void)
6542 struct task_struct
*g
, *p
;
6543 unsigned long flags
;
6547 read_lock_irq(&tasklist_lock
);
6548 do_each_thread(g
, p
) {
6550 p
->se
.wait_runtime
= 0;
6551 p
->se
.exec_start
= 0;
6552 p
->se
.wait_start_fair
= 0;
6553 p
->se
.sleep_start_fair
= 0;
6554 #ifdef CONFIG_SCHEDSTATS
6555 p
->se
.wait_start
= 0;
6556 p
->se
.sleep_start
= 0;
6557 p
->se
.block_start
= 0;
6559 task_rq(p
)->cfs
.fair_clock
= 0;
6560 task_rq(p
)->clock
= 0;
6564 * Renice negative nice level userspace
6567 if (TASK_NICE(p
) < 0 && p
->mm
)
6568 set_user_nice(p
, 0);
6572 spin_lock_irqsave(&p
->pi_lock
, flags
);
6573 rq
= __task_rq_lock(p
);
6576 * Do not touch the migration thread:
6578 if (p
== rq
->migration_thread
)
6582 update_rq_clock(rq
);
6583 on_rq
= p
->se
.on_rq
;
6585 deactivate_task(rq
, p
, 0);
6586 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
6588 activate_task(rq
, p
, 0);
6589 resched_task(rq
->curr
);
6594 __task_rq_unlock(rq
);
6595 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
6596 } while_each_thread(g
, p
);
6598 read_unlock_irq(&tasklist_lock
);
6601 #endif /* CONFIG_MAGIC_SYSRQ */
6605 * These functions are only useful for the IA64 MCA handling.
6607 * They can only be called when the whole system has been
6608 * stopped - every CPU needs to be quiescent, and no scheduling
6609 * activity can take place. Using them for anything else would
6610 * be a serious bug, and as a result, they aren't even visible
6611 * under any other configuration.
6615 * curr_task - return the current task for a given cpu.
6616 * @cpu: the processor in question.
6618 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6620 struct task_struct
*curr_task(int cpu
)
6622 return cpu_curr(cpu
);
6626 * set_curr_task - set the current task for a given cpu.
6627 * @cpu: the processor in question.
6628 * @p: the task pointer to set.
6630 * Description: This function must only be used when non-maskable interrupts
6631 * are serviced on a separate stack. It allows the architecture to switch the
6632 * notion of the current task on a cpu in a non-blocking manner. This function
6633 * must be called with all CPU's synchronized, and interrupts disabled, the
6634 * and caller must save the original value of the current task (see
6635 * curr_task() above) and restore that value before reenabling interrupts and
6636 * re-starting the system.
6638 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6640 void set_curr_task(int cpu
, struct task_struct
*p
)