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
;
176 u64 load_update_start
, load_update_last
;
177 unsigned long delta_fair
, delta_exec
, delta_stat
;
180 /* CFS-related fields in a runqueue */
182 struct load_weight load
;
183 unsigned long nr_running
;
189 unsigned long wait_runtime_overruns
, wait_runtime_underruns
;
191 struct rb_root tasks_timeline
;
192 struct rb_node
*rb_leftmost
;
193 struct rb_node
*rb_load_balance_curr
;
194 #ifdef CONFIG_FAIR_GROUP_SCHED
195 /* 'curr' points to currently running entity on this cfs_rq.
196 * It is set to NULL otherwise (i.e when none are currently running).
198 struct sched_entity
*curr
;
199 struct rq
*rq
; /* cpu runqueue to which this cfs_rq is attached */
201 /* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
202 * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
203 * (like users, containers etc.)
205 * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
206 * list is used during load balance.
208 struct list_head leaf_cfs_rq_list
; /* Better name : task_cfs_rq_list? */
212 /* Real-Time classes' related field in a runqueue: */
214 struct rt_prio_array active
;
215 int rt_load_balance_idx
;
216 struct list_head
*rt_load_balance_head
, *rt_load_balance_curr
;
220 * This is the main, per-CPU runqueue data structure.
222 * Locking rule: those places that want to lock multiple runqueues
223 * (such as the load balancing or the thread migration code), lock
224 * acquire operations must be ordered by ascending &runqueue.
227 spinlock_t lock
; /* runqueue lock */
230 * nr_running and cpu_load should be in the same cacheline because
231 * remote CPUs use both these fields when doing load calculation.
233 unsigned long nr_running
;
234 #define CPU_LOAD_IDX_MAX 5
235 unsigned long cpu_load
[CPU_LOAD_IDX_MAX
];
236 unsigned char idle_at_tick
;
238 unsigned char in_nohz_recently
;
240 struct load_stat ls
; /* capture load from *all* tasks on this cpu */
241 unsigned long nr_load_updates
;
245 #ifdef CONFIG_FAIR_GROUP_SCHED
246 struct list_head leaf_cfs_rq_list
; /* list of leaf cfs_rq on this cpu */
251 * This is part of a global counter where only the total sum
252 * over all CPUs matters. A task can increase this counter on
253 * one CPU and if it got migrated afterwards it may decrease
254 * it on another CPU. Always updated under the runqueue lock:
256 unsigned long nr_uninterruptible
;
258 struct task_struct
*curr
, *idle
;
259 unsigned long next_balance
;
260 struct mm_struct
*prev_mm
;
262 u64 clock
, prev_clock_raw
;
265 unsigned int clock_warps
, clock_overflows
;
267 unsigned int clock_deep_idle_events
;
273 struct sched_domain
*sd
;
275 /* For active balancing */
278 int cpu
; /* cpu of this runqueue */
280 struct task_struct
*migration_thread
;
281 struct list_head migration_queue
;
284 #ifdef CONFIG_SCHEDSTATS
286 struct sched_info rq_sched_info
;
288 /* sys_sched_yield() stats */
289 unsigned long yld_exp_empty
;
290 unsigned long yld_act_empty
;
291 unsigned long yld_both_empty
;
292 unsigned long yld_cnt
;
294 /* schedule() stats */
295 unsigned long sched_switch
;
296 unsigned long sched_cnt
;
297 unsigned long sched_goidle
;
299 /* try_to_wake_up() stats */
300 unsigned long ttwu_cnt
;
301 unsigned long ttwu_local
;
303 struct lock_class_key rq_lock_key
;
306 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq
, runqueues
);
307 static DEFINE_MUTEX(sched_hotcpu_mutex
);
309 static inline void check_preempt_curr(struct rq
*rq
, struct task_struct
*p
)
311 rq
->curr
->sched_class
->check_preempt_curr(rq
, p
);
314 static inline int cpu_of(struct rq
*rq
)
324 * Update the per-runqueue clock, as finegrained as the platform can give
325 * us, but without assuming monotonicity, etc.:
327 static void __update_rq_clock(struct rq
*rq
)
329 u64 prev_raw
= rq
->prev_clock_raw
;
330 u64 now
= sched_clock();
331 s64 delta
= now
- prev_raw
;
332 u64 clock
= rq
->clock
;
334 #ifdef CONFIG_SCHED_DEBUG
335 WARN_ON_ONCE(cpu_of(rq
) != smp_processor_id());
338 * Protect against sched_clock() occasionally going backwards:
340 if (unlikely(delta
< 0)) {
345 * Catch too large forward jumps too:
347 if (unlikely(clock
+ delta
> rq
->tick_timestamp
+ TICK_NSEC
)) {
348 if (clock
< rq
->tick_timestamp
+ TICK_NSEC
)
349 clock
= rq
->tick_timestamp
+ TICK_NSEC
;
352 rq
->clock_overflows
++;
354 if (unlikely(delta
> rq
->clock_max_delta
))
355 rq
->clock_max_delta
= delta
;
360 rq
->prev_clock_raw
= now
;
364 static void update_rq_clock(struct rq
*rq
)
366 if (likely(smp_processor_id() == cpu_of(rq
)))
367 __update_rq_clock(rq
);
371 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
372 * See detach_destroy_domains: synchronize_sched for details.
374 * The domain tree of any CPU may only be accessed from within
375 * preempt-disabled sections.
377 #define for_each_domain(cpu, __sd) \
378 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
380 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
381 #define this_rq() (&__get_cpu_var(runqueues))
382 #define task_rq(p) cpu_rq(task_cpu(p))
383 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
386 * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
387 * clock constructed from sched_clock():
389 unsigned long long cpu_clock(int cpu
)
391 unsigned long long now
;
395 local_irq_save(flags
);
399 local_irq_restore(flags
);
404 #ifdef CONFIG_FAIR_GROUP_SCHED
405 /* Change a task's ->cfs_rq if it moves across CPUs */
406 static inline void set_task_cfs_rq(struct task_struct
*p
)
408 p
->se
.cfs_rq
= &task_rq(p
)->cfs
;
411 static inline void set_task_cfs_rq(struct task_struct
*p
)
416 #ifndef prepare_arch_switch
417 # define prepare_arch_switch(next) do { } while (0)
419 #ifndef finish_arch_switch
420 # define finish_arch_switch(prev) do { } while (0)
423 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
424 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
426 return rq
->curr
== p
;
429 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
433 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
435 #ifdef CONFIG_DEBUG_SPINLOCK
436 /* this is a valid case when another task releases the spinlock */
437 rq
->lock
.owner
= current
;
440 * If we are tracking spinlock dependencies then we have to
441 * fix up the runqueue lock - which gets 'carried over' from
444 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
446 spin_unlock_irq(&rq
->lock
);
449 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
450 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
455 return rq
->curr
== p
;
459 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
463 * We can optimise this out completely for !SMP, because the
464 * SMP rebalancing from interrupt is the only thing that cares
469 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
470 spin_unlock_irq(&rq
->lock
);
472 spin_unlock(&rq
->lock
);
476 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
480 * After ->oncpu is cleared, the task can be moved to a different CPU.
481 * We must ensure this doesn't happen until the switch is completely
487 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
491 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
494 * __task_rq_lock - lock the runqueue a given task resides on.
495 * Must be called interrupts disabled.
497 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
504 spin_lock(&rq
->lock
);
505 if (unlikely(rq
!= task_rq(p
))) {
506 spin_unlock(&rq
->lock
);
507 goto repeat_lock_task
;
513 * task_rq_lock - lock the runqueue a given task resides on and disable
514 * interrupts. Note the ordering: we can safely lookup the task_rq without
515 * explicitly disabling preemption.
517 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
523 local_irq_save(*flags
);
525 spin_lock(&rq
->lock
);
526 if (unlikely(rq
!= task_rq(p
))) {
527 spin_unlock_irqrestore(&rq
->lock
, *flags
);
528 goto repeat_lock_task
;
533 static inline void __task_rq_unlock(struct rq
*rq
)
536 spin_unlock(&rq
->lock
);
539 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
542 spin_unlock_irqrestore(&rq
->lock
, *flags
);
546 * this_rq_lock - lock this runqueue and disable interrupts.
548 static inline struct rq
*this_rq_lock(void)
555 spin_lock(&rq
->lock
);
561 * We are going deep-idle (irqs are disabled):
563 void sched_clock_idle_sleep_event(void)
565 struct rq
*rq
= cpu_rq(smp_processor_id());
567 spin_lock(&rq
->lock
);
568 __update_rq_clock(rq
);
569 spin_unlock(&rq
->lock
);
570 rq
->clock_deep_idle_events
++;
572 EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event
);
575 * We just idled delta nanoseconds (called with irqs disabled):
577 void sched_clock_idle_wakeup_event(u64 delta_ns
)
579 struct rq
*rq
= cpu_rq(smp_processor_id());
580 u64 now
= sched_clock();
582 rq
->idle_clock
+= delta_ns
;
584 * Override the previous timestamp and ignore all
585 * sched_clock() deltas that occured while we idled,
586 * and use the PM-provided delta_ns to advance the
589 spin_lock(&rq
->lock
);
590 rq
->prev_clock_raw
= now
;
591 rq
->clock
+= delta_ns
;
592 spin_unlock(&rq
->lock
);
594 EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event
);
597 * resched_task - mark a task 'to be rescheduled now'.
599 * On UP this means the setting of the need_resched flag, on SMP it
600 * might also involve a cross-CPU call to trigger the scheduler on
605 #ifndef tsk_is_polling
606 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
609 static void resched_task(struct task_struct
*p
)
613 assert_spin_locked(&task_rq(p
)->lock
);
615 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
618 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
621 if (cpu
== smp_processor_id())
624 /* NEED_RESCHED must be visible before we test polling */
626 if (!tsk_is_polling(p
))
627 smp_send_reschedule(cpu
);
630 static void resched_cpu(int cpu
)
632 struct rq
*rq
= cpu_rq(cpu
);
635 if (!spin_trylock_irqsave(&rq
->lock
, flags
))
637 resched_task(cpu_curr(cpu
));
638 spin_unlock_irqrestore(&rq
->lock
, flags
);
641 static inline void resched_task(struct task_struct
*p
)
643 assert_spin_locked(&task_rq(p
)->lock
);
644 set_tsk_need_resched(p
);
648 static u64
div64_likely32(u64 divident
, unsigned long divisor
)
650 #if BITS_PER_LONG == 32
651 if (likely(divident
<= 0xffffffffULL
))
652 return (u32
)divident
/ divisor
;
653 do_div(divident
, divisor
);
657 return divident
/ divisor
;
661 #if BITS_PER_LONG == 32
662 # define WMULT_CONST (~0UL)
664 # define WMULT_CONST (1UL << 32)
667 #define WMULT_SHIFT 32
670 * Shift right and round:
672 #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
675 calc_delta_mine(unsigned long delta_exec
, unsigned long weight
,
676 struct load_weight
*lw
)
680 if (unlikely(!lw
->inv_weight
))
681 lw
->inv_weight
= (WMULT_CONST
- lw
->weight
/2) / lw
->weight
+ 1;
683 tmp
= (u64
)delta_exec
* weight
;
685 * Check whether we'd overflow the 64-bit multiplication:
687 if (unlikely(tmp
> WMULT_CONST
))
688 tmp
= SRR(SRR(tmp
, WMULT_SHIFT
/2) * lw
->inv_weight
,
691 tmp
= SRR(tmp
* lw
->inv_weight
, WMULT_SHIFT
);
693 return (unsigned long)min(tmp
, (u64
)(unsigned long)LONG_MAX
);
696 static inline unsigned long
697 calc_delta_fair(unsigned long delta_exec
, struct load_weight
*lw
)
699 return calc_delta_mine(delta_exec
, NICE_0_LOAD
, lw
);
702 static void update_load_add(struct load_weight
*lw
, unsigned long inc
)
708 static void update_load_sub(struct load_weight
*lw
, unsigned long dec
)
715 * To aid in avoiding the subversion of "niceness" due to uneven distribution
716 * of tasks with abnormal "nice" values across CPUs the contribution that
717 * each task makes to its run queue's load is weighted according to its
718 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
719 * scaled version of the new time slice allocation that they receive on time
723 #define WEIGHT_IDLEPRIO 2
724 #define WMULT_IDLEPRIO (1 << 31)
727 * Nice levels are multiplicative, with a gentle 10% change for every
728 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
729 * nice 1, it will get ~10% less CPU time than another CPU-bound task
730 * that remained on nice 0.
732 * The "10% effect" is relative and cumulative: from _any_ nice level,
733 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
734 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
735 * If a task goes up by ~10% and another task goes down by ~10% then
736 * the relative distance between them is ~25%.)
738 static const int prio_to_weight
[40] = {
739 /* -20 */ 88761, 71755, 56483, 46273, 36291,
740 /* -15 */ 29154, 23254, 18705, 14949, 11916,
741 /* -10 */ 9548, 7620, 6100, 4904, 3906,
742 /* -5 */ 3121, 2501, 1991, 1586, 1277,
743 /* 0 */ 1024, 820, 655, 526, 423,
744 /* 5 */ 335, 272, 215, 172, 137,
745 /* 10 */ 110, 87, 70, 56, 45,
746 /* 15 */ 36, 29, 23, 18, 15,
750 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
752 * In cases where the weight does not change often, we can use the
753 * precalculated inverse to speed up arithmetics by turning divisions
754 * into multiplications:
756 static const u32 prio_to_wmult
[40] = {
757 /* -20 */ 48388, 59856, 76040, 92818, 118348,
758 /* -15 */ 147320, 184698, 229616, 287308, 360437,
759 /* -10 */ 449829, 563644, 704093, 875809, 1099582,
760 /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
761 /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
762 /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
763 /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
764 /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
767 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
);
770 * runqueue iterator, to support SMP load-balancing between different
771 * scheduling classes, without having to expose their internal data
772 * structures to the load-balancing proper:
776 struct task_struct
*(*start
)(void *);
777 struct task_struct
*(*next
)(void *);
780 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
781 unsigned long max_nr_move
, unsigned long max_load_move
,
782 struct sched_domain
*sd
, enum cpu_idle_type idle
,
783 int *all_pinned
, unsigned long *load_moved
,
784 int *this_best_prio
, struct rq_iterator
*iterator
);
786 #include "sched_stats.h"
787 #include "sched_rt.c"
788 #include "sched_fair.c"
789 #include "sched_idletask.c"
790 #ifdef CONFIG_SCHED_DEBUG
791 # include "sched_debug.c"
794 #define sched_class_highest (&rt_sched_class)
796 static void __update_curr_load(struct rq
*rq
, struct load_stat
*ls
)
798 if (rq
->curr
!= rq
->idle
&& ls
->load
.weight
) {
799 ls
->delta_exec
+= ls
->delta_stat
;
800 ls
->delta_fair
+= calc_delta_fair(ls
->delta_stat
, &ls
->load
);
806 * Update delta_exec, delta_fair fields for rq.
808 * delta_fair clock advances at a rate inversely proportional to
809 * total load (rq->ls.load.weight) on the runqueue, while
810 * delta_exec advances at the same rate as wall-clock (provided
813 * delta_exec / delta_fair is a measure of the (smoothened) load on this
814 * runqueue over any given interval. This (smoothened) load is used
815 * during load balance.
817 * This function is called /before/ updating rq->ls.load
818 * and when switching tasks.
820 static void update_curr_load(struct rq
*rq
)
822 struct load_stat
*ls
= &rq
->ls
;
825 start
= ls
->load_update_start
;
826 ls
->load_update_start
= rq
->clock
;
827 ls
->delta_stat
+= rq
->clock
- start
;
829 * Stagger updates to ls->delta_fair. Very frequent updates
833 __update_curr_load(rq
, ls
);
836 static inline void inc_load(struct rq
*rq
, const struct task_struct
*p
)
838 update_curr_load(rq
);
839 update_load_add(&rq
->ls
.load
, p
->se
.load
.weight
);
842 static inline void dec_load(struct rq
*rq
, const struct task_struct
*p
)
844 update_curr_load(rq
);
845 update_load_sub(&rq
->ls
.load
, p
->se
.load
.weight
);
848 static void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
854 static void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
860 static void set_load_weight(struct task_struct
*p
)
862 p
->se
.wait_runtime
= 0;
864 if (task_has_rt_policy(p
)) {
865 p
->se
.load
.weight
= prio_to_weight
[0] * 2;
866 p
->se
.load
.inv_weight
= prio_to_wmult
[0] >> 1;
871 * SCHED_IDLE tasks get minimal weight:
873 if (p
->policy
== SCHED_IDLE
) {
874 p
->se
.load
.weight
= WEIGHT_IDLEPRIO
;
875 p
->se
.load
.inv_weight
= WMULT_IDLEPRIO
;
879 p
->se
.load
.weight
= prio_to_weight
[p
->static_prio
- MAX_RT_PRIO
];
880 p
->se
.load
.inv_weight
= prio_to_wmult
[p
->static_prio
- MAX_RT_PRIO
];
883 static void enqueue_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
885 sched_info_queued(p
);
886 p
->sched_class
->enqueue_task(rq
, p
, wakeup
);
890 static void dequeue_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
892 p
->sched_class
->dequeue_task(rq
, p
, sleep
);
897 * __normal_prio - return the priority that is based on the static prio
899 static inline int __normal_prio(struct task_struct
*p
)
901 return p
->static_prio
;
905 * Calculate the expected normal priority: i.e. priority
906 * without taking RT-inheritance into account. Might be
907 * boosted by interactivity modifiers. Changes upon fork,
908 * setprio syscalls, and whenever the interactivity
909 * estimator recalculates.
911 static inline int normal_prio(struct task_struct
*p
)
915 if (task_has_rt_policy(p
))
916 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
918 prio
= __normal_prio(p
);
923 * Calculate the current priority, i.e. the priority
924 * taken into account by the scheduler. This value might
925 * be boosted by RT tasks, or might be boosted by
926 * interactivity modifiers. Will be RT if the task got
927 * RT-boosted. If not then it returns p->normal_prio.
929 static int effective_prio(struct task_struct
*p
)
931 p
->normal_prio
= normal_prio(p
);
933 * If we are RT tasks or we were boosted to RT priority,
934 * keep the priority unchanged. Otherwise, update priority
935 * to the normal priority:
937 if (!rt_prio(p
->prio
))
938 return p
->normal_prio
;
943 * activate_task - move a task to the runqueue.
945 static void activate_task(struct rq
*rq
, struct task_struct
*p
, int wakeup
)
947 if (p
->state
== TASK_UNINTERRUPTIBLE
)
948 rq
->nr_uninterruptible
--;
950 enqueue_task(rq
, p
, wakeup
);
951 inc_nr_running(p
, rq
);
955 * activate_idle_task - move idle task to the _front_ of runqueue.
957 static inline void activate_idle_task(struct task_struct
*p
, struct rq
*rq
)
961 if (p
->state
== TASK_UNINTERRUPTIBLE
)
962 rq
->nr_uninterruptible
--;
964 enqueue_task(rq
, p
, 0);
965 inc_nr_running(p
, rq
);
969 * deactivate_task - remove a task from the runqueue.
971 static void deactivate_task(struct rq
*rq
, struct task_struct
*p
, int sleep
)
973 if (p
->state
== TASK_UNINTERRUPTIBLE
)
974 rq
->nr_uninterruptible
++;
976 dequeue_task(rq
, p
, sleep
);
977 dec_nr_running(p
, rq
);
981 * task_curr - is this task currently executing on a CPU?
982 * @p: the task in question.
984 inline int task_curr(const struct task_struct
*p
)
986 return cpu_curr(task_cpu(p
)) == p
;
989 /* Used instead of source_load when we know the type == 0 */
990 unsigned long weighted_cpuload(const int cpu
)
992 return cpu_rq(cpu
)->ls
.load
.weight
;
995 static inline void __set_task_cpu(struct task_struct
*p
, unsigned int cpu
)
998 task_thread_info(p
)->cpu
= cpu
;
1005 void set_task_cpu(struct task_struct
*p
, unsigned int new_cpu
)
1007 int old_cpu
= task_cpu(p
);
1008 struct rq
*old_rq
= cpu_rq(old_cpu
), *new_rq
= cpu_rq(new_cpu
);
1009 u64 clock_offset
, fair_clock_offset
;
1011 clock_offset
= old_rq
->clock
- new_rq
->clock
;
1012 fair_clock_offset
= old_rq
->cfs
.fair_clock
- new_rq
->cfs
.fair_clock
;
1014 if (p
->se
.wait_start_fair
)
1015 p
->se
.wait_start_fair
-= fair_clock_offset
;
1016 if (p
->se
.sleep_start_fair
)
1017 p
->se
.sleep_start_fair
-= fair_clock_offset
;
1019 #ifdef CONFIG_SCHEDSTATS
1020 if (p
->se
.wait_start
)
1021 p
->se
.wait_start
-= clock_offset
;
1022 if (p
->se
.sleep_start
)
1023 p
->se
.sleep_start
-= clock_offset
;
1024 if (p
->se
.block_start
)
1025 p
->se
.block_start
-= clock_offset
;
1028 __set_task_cpu(p
, new_cpu
);
1031 struct migration_req
{
1032 struct list_head list
;
1034 struct task_struct
*task
;
1037 struct completion done
;
1041 * The task's runqueue lock must be held.
1042 * Returns true if you have to wait for migration thread.
1045 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1047 struct rq
*rq
= task_rq(p
);
1050 * If the task is not on a runqueue (and not running), then
1051 * it is sufficient to simply update the task's cpu field.
1053 if (!p
->se
.on_rq
&& !task_running(rq
, p
)) {
1054 set_task_cpu(p
, dest_cpu
);
1058 init_completion(&req
->done
);
1060 req
->dest_cpu
= dest_cpu
;
1061 list_add(&req
->list
, &rq
->migration_queue
);
1067 * wait_task_inactive - wait for a thread to unschedule.
1069 * The caller must ensure that the task *will* unschedule sometime soon,
1070 * else this function might spin for a *long* time. This function can't
1071 * be called with interrupts off, or it may introduce deadlock with
1072 * smp_call_function() if an IPI is sent by the same process we are
1073 * waiting to become inactive.
1075 void wait_task_inactive(struct task_struct
*p
)
1077 unsigned long flags
;
1083 * We do the initial early heuristics without holding
1084 * any task-queue locks at all. We'll only try to get
1085 * the runqueue lock when things look like they will
1091 * If the task is actively running on another CPU
1092 * still, just relax and busy-wait without holding
1095 * NOTE! Since we don't hold any locks, it's not
1096 * even sure that "rq" stays as the right runqueue!
1097 * But we don't care, since "task_running()" will
1098 * return false if the runqueue has changed and p
1099 * is actually now running somewhere else!
1101 while (task_running(rq
, p
))
1105 * Ok, time to look more closely! We need the rq
1106 * lock now, to be *sure*. If we're wrong, we'll
1107 * just go back and repeat.
1109 rq
= task_rq_lock(p
, &flags
);
1110 running
= task_running(rq
, p
);
1111 on_rq
= p
->se
.on_rq
;
1112 task_rq_unlock(rq
, &flags
);
1115 * Was it really running after all now that we
1116 * checked with the proper locks actually held?
1118 * Oops. Go back and try again..
1120 if (unlikely(running
)) {
1126 * It's not enough that it's not actively running,
1127 * it must be off the runqueue _entirely_, and not
1130 * So if it wa still runnable (but just not actively
1131 * running right now), it's preempted, and we should
1132 * yield - it could be a while.
1134 if (unlikely(on_rq
)) {
1140 * Ahh, all good. It wasn't running, and it wasn't
1141 * runnable, which means that it will never become
1142 * running in the future either. We're all done!
1147 * kick_process - kick a running thread to enter/exit the kernel
1148 * @p: the to-be-kicked thread
1150 * Cause a process which is running on another CPU to enter
1151 * kernel-mode, without any delay. (to get signals handled.)
1153 * NOTE: this function doesnt have to take the runqueue lock,
1154 * because all it wants to ensure is that the remote task enters
1155 * the kernel. If the IPI races and the task has been migrated
1156 * to another CPU then no harm is done and the purpose has been
1159 void kick_process(struct task_struct
*p
)
1165 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1166 smp_send_reschedule(cpu
);
1171 * Return a low guess at the load of a migration-source cpu weighted
1172 * according to the scheduling class and "nice" value.
1174 * We want to under-estimate the load of migration sources, to
1175 * balance conservatively.
1177 static inline unsigned long source_load(int cpu
, int type
)
1179 struct rq
*rq
= cpu_rq(cpu
);
1180 unsigned long total
= weighted_cpuload(cpu
);
1185 return min(rq
->cpu_load
[type
-1], total
);
1189 * Return a high guess at the load of a migration-target cpu weighted
1190 * according to the scheduling class and "nice" value.
1192 static inline unsigned long target_load(int cpu
, int type
)
1194 struct rq
*rq
= cpu_rq(cpu
);
1195 unsigned long total
= weighted_cpuload(cpu
);
1200 return max(rq
->cpu_load
[type
-1], total
);
1204 * Return the average load per task on the cpu's run queue
1206 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1208 struct rq
*rq
= cpu_rq(cpu
);
1209 unsigned long total
= weighted_cpuload(cpu
);
1210 unsigned long n
= rq
->nr_running
;
1212 return n
? total
/ n
: SCHED_LOAD_SCALE
;
1216 * find_idlest_group finds and returns the least busy CPU group within the
1219 static struct sched_group
*
1220 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1222 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1223 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1224 int load_idx
= sd
->forkexec_idx
;
1225 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1228 unsigned long load
, avg_load
;
1232 /* Skip over this group if it has no CPUs allowed */
1233 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1236 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1238 /* Tally up the load of all CPUs in the group */
1241 for_each_cpu_mask(i
, group
->cpumask
) {
1242 /* Bias balancing toward cpus of our domain */
1244 load
= source_load(i
, load_idx
);
1246 load
= target_load(i
, load_idx
);
1251 /* Adjust by relative CPU power of the group */
1252 avg_load
= sg_div_cpu_power(group
,
1253 avg_load
* SCHED_LOAD_SCALE
);
1256 this_load
= avg_load
;
1258 } else if (avg_load
< min_load
) {
1259 min_load
= avg_load
;
1263 group
= group
->next
;
1264 } while (group
!= sd
->groups
);
1266 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1272 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1275 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1278 unsigned long load
, min_load
= ULONG_MAX
;
1282 /* Traverse only the allowed CPUs */
1283 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1285 for_each_cpu_mask(i
, tmp
) {
1286 load
= weighted_cpuload(i
);
1288 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1298 * sched_balance_self: balance the current task (running on cpu) in domains
1299 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1302 * Balance, ie. select the least loaded group.
1304 * Returns the target CPU number, or the same CPU if no balancing is needed.
1306 * preempt must be disabled.
1308 static int sched_balance_self(int cpu
, int flag
)
1310 struct task_struct
*t
= current
;
1311 struct sched_domain
*tmp
, *sd
= NULL
;
1313 for_each_domain(cpu
, tmp
) {
1315 * If power savings logic is enabled for a domain, stop there.
1317 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1319 if (tmp
->flags
& flag
)
1325 struct sched_group
*group
;
1326 int new_cpu
, weight
;
1328 if (!(sd
->flags
& flag
)) {
1334 group
= find_idlest_group(sd
, t
, cpu
);
1340 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1341 if (new_cpu
== -1 || new_cpu
== cpu
) {
1342 /* Now try balancing at a lower domain level of cpu */
1347 /* Now try balancing at a lower domain level of new_cpu */
1350 weight
= cpus_weight(span
);
1351 for_each_domain(cpu
, tmp
) {
1352 if (weight
<= cpus_weight(tmp
->span
))
1354 if (tmp
->flags
& flag
)
1357 /* while loop will break here if sd == NULL */
1363 #endif /* CONFIG_SMP */
1366 * wake_idle() will wake a task on an idle cpu if task->cpu is
1367 * not idle and an idle cpu is available. The span of cpus to
1368 * search starts with cpus closest then further out as needed,
1369 * so we always favor a closer, idle cpu.
1371 * Returns the CPU we should wake onto.
1373 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1374 static int wake_idle(int cpu
, struct task_struct
*p
)
1377 struct sched_domain
*sd
;
1381 * If it is idle, then it is the best cpu to run this task.
1383 * This cpu is also the best, if it has more than one task already.
1384 * Siblings must be also busy(in most cases) as they didn't already
1385 * pickup the extra load from this cpu and hence we need not check
1386 * sibling runqueue info. This will avoid the checks and cache miss
1387 * penalities associated with that.
1389 if (idle_cpu(cpu
) || cpu_rq(cpu
)->nr_running
> 1)
1392 for_each_domain(cpu
, sd
) {
1393 if (sd
->flags
& SD_WAKE_IDLE
) {
1394 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1395 for_each_cpu_mask(i
, tmp
) {
1406 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1413 * try_to_wake_up - wake up a thread
1414 * @p: the to-be-woken-up thread
1415 * @state: the mask of task states that can be woken
1416 * @sync: do a synchronous wakeup?
1418 * Put it on the run-queue if it's not already there. The "current"
1419 * thread is always on the run-queue (except when the actual
1420 * re-schedule is in progress), and as such you're allowed to do
1421 * the simpler "current->state = TASK_RUNNING" to mark yourself
1422 * runnable without the overhead of this.
1424 * returns failure only if the task is already active.
1426 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1428 int cpu
, this_cpu
, success
= 0;
1429 unsigned long flags
;
1433 struct sched_domain
*sd
, *this_sd
= NULL
;
1434 unsigned long load
, this_load
;
1438 rq
= task_rq_lock(p
, &flags
);
1439 old_state
= p
->state
;
1440 if (!(old_state
& state
))
1447 this_cpu
= smp_processor_id();
1450 if (unlikely(task_running(rq
, p
)))
1455 schedstat_inc(rq
, ttwu_cnt
);
1456 if (cpu
== this_cpu
) {
1457 schedstat_inc(rq
, ttwu_local
);
1461 for_each_domain(this_cpu
, sd
) {
1462 if (cpu_isset(cpu
, sd
->span
)) {
1463 schedstat_inc(sd
, ttwu_wake_remote
);
1469 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1473 * Check for affine wakeup and passive balancing possibilities.
1476 int idx
= this_sd
->wake_idx
;
1477 unsigned int imbalance
;
1479 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1481 load
= source_load(cpu
, idx
);
1482 this_load
= target_load(this_cpu
, idx
);
1484 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1486 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1487 unsigned long tl
= this_load
;
1488 unsigned long tl_per_task
;
1490 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1493 * If sync wakeup then subtract the (maximum possible)
1494 * effect of the currently running task from the load
1495 * of the current CPU:
1498 tl
-= current
->se
.load
.weight
;
1501 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1502 100*(tl
+ p
->se
.load
.weight
) <= imbalance
*load
) {
1504 * This domain has SD_WAKE_AFFINE and
1505 * p is cache cold in this domain, and
1506 * there is no bad imbalance.
1508 schedstat_inc(this_sd
, ttwu_move_affine
);
1514 * Start passive balancing when half the imbalance_pct
1517 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1518 if (imbalance
*this_load
<= 100*load
) {
1519 schedstat_inc(this_sd
, ttwu_move_balance
);
1525 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1527 new_cpu
= wake_idle(new_cpu
, p
);
1528 if (new_cpu
!= cpu
) {
1529 set_task_cpu(p
, new_cpu
);
1530 task_rq_unlock(rq
, &flags
);
1531 /* might preempt at this point */
1532 rq
= task_rq_lock(p
, &flags
);
1533 old_state
= p
->state
;
1534 if (!(old_state
& state
))
1539 this_cpu
= smp_processor_id();
1544 #endif /* CONFIG_SMP */
1545 update_rq_clock(rq
);
1546 activate_task(rq
, p
, 1);
1548 * Sync wakeups (i.e. those types of wakeups where the waker
1549 * has indicated that it will leave the CPU in short order)
1550 * don't trigger a preemption, if the woken up task will run on
1551 * this cpu. (in this case the 'I will reschedule' promise of
1552 * the waker guarantees that the freshly woken up task is going
1553 * to be considered on this CPU.)
1555 if (!sync
|| cpu
!= this_cpu
)
1556 check_preempt_curr(rq
, p
);
1560 p
->state
= TASK_RUNNING
;
1562 task_rq_unlock(rq
, &flags
);
1567 int fastcall
wake_up_process(struct task_struct
*p
)
1569 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1570 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1572 EXPORT_SYMBOL(wake_up_process
);
1574 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1576 return try_to_wake_up(p
, state
, 0);
1580 * Perform scheduler related setup for a newly forked process p.
1581 * p is forked by current.
1583 * __sched_fork() is basic setup used by init_idle() too:
1585 static void __sched_fork(struct task_struct
*p
)
1587 p
->se
.wait_start_fair
= 0;
1588 p
->se
.exec_start
= 0;
1589 p
->se
.sum_exec_runtime
= 0;
1590 p
->se
.prev_sum_exec_runtime
= 0;
1591 p
->se
.wait_runtime
= 0;
1592 p
->se
.sleep_start_fair
= 0;
1594 #ifdef CONFIG_SCHEDSTATS
1595 p
->se
.wait_start
= 0;
1596 p
->se
.sum_wait_runtime
= 0;
1597 p
->se
.sum_sleep_runtime
= 0;
1598 p
->se
.sleep_start
= 0;
1599 p
->se
.block_start
= 0;
1600 p
->se
.sleep_max
= 0;
1601 p
->se
.block_max
= 0;
1603 p
->se
.slice_max
= 0;
1605 p
->se
.wait_runtime_overruns
= 0;
1606 p
->se
.wait_runtime_underruns
= 0;
1609 INIT_LIST_HEAD(&p
->run_list
);
1612 #ifdef CONFIG_PREEMPT_NOTIFIERS
1613 INIT_HLIST_HEAD(&p
->preempt_notifiers
);
1617 * We mark the process as running here, but have not actually
1618 * inserted it onto the runqueue yet. This guarantees that
1619 * nobody will actually run it, and a signal or other external
1620 * event cannot wake it up and insert it on the runqueue either.
1622 p
->state
= TASK_RUNNING
;
1626 * fork()/clone()-time setup:
1628 void sched_fork(struct task_struct
*p
, int clone_flags
)
1630 int cpu
= get_cpu();
1635 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1637 __set_task_cpu(p
, cpu
);
1640 * Make sure we do not leak PI boosting priority to the child:
1642 p
->prio
= current
->normal_prio
;
1644 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1645 if (likely(sched_info_on()))
1646 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1648 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1651 #ifdef CONFIG_PREEMPT
1652 /* Want to start with kernel preemption disabled. */
1653 task_thread_info(p
)->preempt_count
= 1;
1659 * wake_up_new_task - wake up a newly created task for the first time.
1661 * This function will do some initial scheduler statistics housekeeping
1662 * that must be done for every newly created context, then puts the task
1663 * on the runqueue and wakes it.
1665 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1667 unsigned long flags
;
1671 rq
= task_rq_lock(p
, &flags
);
1672 BUG_ON(p
->state
!= TASK_RUNNING
);
1673 this_cpu
= smp_processor_id(); /* parent's CPU */
1674 update_rq_clock(rq
);
1676 p
->prio
= effective_prio(p
);
1678 if (rt_prio(p
->prio
))
1679 p
->sched_class
= &rt_sched_class
;
1681 p
->sched_class
= &fair_sched_class
;
1683 if (task_cpu(p
) != this_cpu
|| !p
->sched_class
->task_new
||
1684 !current
->se
.on_rq
) {
1685 activate_task(rq
, p
, 0);
1688 * Let the scheduling class do new task startup
1689 * management (if any):
1691 p
->sched_class
->task_new(rq
, p
);
1692 inc_nr_running(p
, rq
);
1694 check_preempt_curr(rq
, p
);
1695 task_rq_unlock(rq
, &flags
);
1698 #ifdef CONFIG_PREEMPT_NOTIFIERS
1701 * preempt_notifier_register - tell me when current is being being preempted & rescheduled
1702 * @notifier: notifier struct to register
1704 void preempt_notifier_register(struct preempt_notifier
*notifier
)
1706 hlist_add_head(¬ifier
->link
, ¤t
->preempt_notifiers
);
1708 EXPORT_SYMBOL_GPL(preempt_notifier_register
);
1711 * preempt_notifier_unregister - no longer interested in preemption notifications
1712 * @notifier: notifier struct to unregister
1714 * This is safe to call from within a preemption notifier.
1716 void preempt_notifier_unregister(struct preempt_notifier
*notifier
)
1718 hlist_del(¬ifier
->link
);
1720 EXPORT_SYMBOL_GPL(preempt_notifier_unregister
);
1722 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1724 struct preempt_notifier
*notifier
;
1725 struct hlist_node
*node
;
1727 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1728 notifier
->ops
->sched_in(notifier
, raw_smp_processor_id());
1732 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1733 struct task_struct
*next
)
1735 struct preempt_notifier
*notifier
;
1736 struct hlist_node
*node
;
1738 hlist_for_each_entry(notifier
, node
, &curr
->preempt_notifiers
, link
)
1739 notifier
->ops
->sched_out(notifier
, next
);
1744 static void fire_sched_in_preempt_notifiers(struct task_struct
*curr
)
1749 fire_sched_out_preempt_notifiers(struct task_struct
*curr
,
1750 struct task_struct
*next
)
1757 * prepare_task_switch - prepare to switch tasks
1758 * @rq: the runqueue preparing to switch
1759 * @prev: the current task that is being switched out
1760 * @next: the task we are going to switch to.
1762 * This is called with the rq lock held and interrupts off. It must
1763 * be paired with a subsequent finish_task_switch after the context
1766 * prepare_task_switch sets up locking and calls architecture specific
1770 prepare_task_switch(struct rq
*rq
, struct task_struct
*prev
,
1771 struct task_struct
*next
)
1773 fire_sched_out_preempt_notifiers(prev
, next
);
1774 prepare_lock_switch(rq
, next
);
1775 prepare_arch_switch(next
);
1779 * finish_task_switch - clean up after a task-switch
1780 * @rq: runqueue associated with task-switch
1781 * @prev: the thread we just switched away from.
1783 * finish_task_switch must be called after the context switch, paired
1784 * with a prepare_task_switch call before the context switch.
1785 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1786 * and do any other architecture-specific cleanup actions.
1788 * Note that we may have delayed dropping an mm in context_switch(). If
1789 * so, we finish that here outside of the runqueue lock. (Doing it
1790 * with the lock held can cause deadlocks; see schedule() for
1793 static inline void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1794 __releases(rq
->lock
)
1796 struct mm_struct
*mm
= rq
->prev_mm
;
1802 * A task struct has one reference for the use as "current".
1803 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1804 * schedule one last time. The schedule call will never return, and
1805 * the scheduled task must drop that reference.
1806 * The test for TASK_DEAD must occur while the runqueue locks are
1807 * still held, otherwise prev could be scheduled on another cpu, die
1808 * there before we look at prev->state, and then the reference would
1810 * Manfred Spraul <manfred@colorfullife.com>
1812 prev_state
= prev
->state
;
1813 finish_arch_switch(prev
);
1814 finish_lock_switch(rq
, prev
);
1815 fire_sched_in_preempt_notifiers(current
);
1818 if (unlikely(prev_state
== TASK_DEAD
)) {
1820 * Remove function-return probe instances associated with this
1821 * task and put them back on the free list.
1823 kprobe_flush_task(prev
);
1824 put_task_struct(prev
);
1829 * schedule_tail - first thing a freshly forked thread must call.
1830 * @prev: the thread we just switched away from.
1832 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1833 __releases(rq
->lock
)
1835 struct rq
*rq
= this_rq();
1837 finish_task_switch(rq
, prev
);
1838 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1839 /* In this case, finish_task_switch does not reenable preemption */
1842 if (current
->set_child_tid
)
1843 put_user(current
->pid
, current
->set_child_tid
);
1847 * context_switch - switch to the new MM and the new
1848 * thread's register state.
1851 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1852 struct task_struct
*next
)
1854 struct mm_struct
*mm
, *oldmm
;
1856 prepare_task_switch(rq
, prev
, next
);
1858 oldmm
= prev
->active_mm
;
1860 * For paravirt, this is coupled with an exit in switch_to to
1861 * combine the page table reload and the switch backend into
1864 arch_enter_lazy_cpu_mode();
1866 if (unlikely(!mm
)) {
1867 next
->active_mm
= oldmm
;
1868 atomic_inc(&oldmm
->mm_count
);
1869 enter_lazy_tlb(oldmm
, next
);
1871 switch_mm(oldmm
, mm
, next
);
1873 if (unlikely(!prev
->mm
)) {
1874 prev
->active_mm
= NULL
;
1875 rq
->prev_mm
= oldmm
;
1878 * Since the runqueue lock will be released by the next
1879 * task (which is an invalid locking op but in the case
1880 * of the scheduler it's an obvious special-case), so we
1881 * do an early lockdep release here:
1883 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1884 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1887 /* Here we just switch the register state and the stack. */
1888 switch_to(prev
, next
, prev
);
1892 * this_rq must be evaluated again because prev may have moved
1893 * CPUs since it called schedule(), thus the 'rq' on its stack
1894 * frame will be invalid.
1896 finish_task_switch(this_rq(), prev
);
1900 * nr_running, nr_uninterruptible and nr_context_switches:
1902 * externally visible scheduler statistics: current number of runnable
1903 * threads, current number of uninterruptible-sleeping threads, total
1904 * number of context switches performed since bootup.
1906 unsigned long nr_running(void)
1908 unsigned long i
, sum
= 0;
1910 for_each_online_cpu(i
)
1911 sum
+= cpu_rq(i
)->nr_running
;
1916 unsigned long nr_uninterruptible(void)
1918 unsigned long i
, sum
= 0;
1920 for_each_possible_cpu(i
)
1921 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1924 * Since we read the counters lockless, it might be slightly
1925 * inaccurate. Do not allow it to go below zero though:
1927 if (unlikely((long)sum
< 0))
1933 unsigned long long nr_context_switches(void)
1936 unsigned long long sum
= 0;
1938 for_each_possible_cpu(i
)
1939 sum
+= cpu_rq(i
)->nr_switches
;
1944 unsigned long nr_iowait(void)
1946 unsigned long i
, sum
= 0;
1948 for_each_possible_cpu(i
)
1949 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1954 unsigned long nr_active(void)
1956 unsigned long i
, running
= 0, uninterruptible
= 0;
1958 for_each_online_cpu(i
) {
1959 running
+= cpu_rq(i
)->nr_running
;
1960 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
1963 if (unlikely((long)uninterruptible
< 0))
1964 uninterruptible
= 0;
1966 return running
+ uninterruptible
;
1970 * Update rq->cpu_load[] statistics. This function is usually called every
1971 * scheduler tick (TICK_NSEC).
1973 static void update_cpu_load(struct rq
*this_rq
)
1975 unsigned long total_load
= this_rq
->ls
.load
.weight
;
1976 unsigned long this_load
= total_load
;
1979 this_rq
->nr_load_updates
++;
1981 /* Update our load: */
1982 for (i
= 0, scale
= 1; i
< CPU_LOAD_IDX_MAX
; i
++, scale
+= scale
) {
1983 unsigned long old_load
, new_load
;
1985 /* scale is effectively 1 << i now, and >> i divides by scale */
1987 old_load
= this_rq
->cpu_load
[i
];
1988 new_load
= this_load
;
1990 * Round up the averaging division if load is increasing. This
1991 * prevents us from getting stuck on 9 if the load is 10, for
1994 if (new_load
> old_load
)
1995 new_load
+= scale
-1;
1996 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2003 * double_rq_lock - safely lock two runqueues
2005 * Note this does not disable interrupts like task_rq_lock,
2006 * you need to do so manually before calling.
2008 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
2009 __acquires(rq1
->lock
)
2010 __acquires(rq2
->lock
)
2012 BUG_ON(!irqs_disabled());
2014 spin_lock(&rq1
->lock
);
2015 __acquire(rq2
->lock
); /* Fake it out ;) */
2018 spin_lock(&rq1
->lock
);
2019 spin_lock(&rq2
->lock
);
2021 spin_lock(&rq2
->lock
);
2022 spin_lock(&rq1
->lock
);
2025 update_rq_clock(rq1
);
2026 update_rq_clock(rq2
);
2030 * double_rq_unlock - safely unlock two runqueues
2032 * Note this does not restore interrupts like task_rq_unlock,
2033 * you need to do so manually after calling.
2035 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2036 __releases(rq1
->lock
)
2037 __releases(rq2
->lock
)
2039 spin_unlock(&rq1
->lock
);
2041 spin_unlock(&rq2
->lock
);
2043 __release(rq2
->lock
);
2047 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2049 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2050 __releases(this_rq
->lock
)
2051 __acquires(busiest
->lock
)
2052 __acquires(this_rq
->lock
)
2054 if (unlikely(!irqs_disabled())) {
2055 /* printk() doesn't work good under rq->lock */
2056 spin_unlock(&this_rq
->lock
);
2059 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2060 if (busiest
< this_rq
) {
2061 spin_unlock(&this_rq
->lock
);
2062 spin_lock(&busiest
->lock
);
2063 spin_lock(&this_rq
->lock
);
2065 spin_lock(&busiest
->lock
);
2070 * If dest_cpu is allowed for this process, migrate the task to it.
2071 * This is accomplished by forcing the cpu_allowed mask to only
2072 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2073 * the cpu_allowed mask is restored.
2075 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2077 struct migration_req req
;
2078 unsigned long flags
;
2081 rq
= task_rq_lock(p
, &flags
);
2082 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2083 || unlikely(cpu_is_offline(dest_cpu
)))
2086 /* force the process onto the specified CPU */
2087 if (migrate_task(p
, dest_cpu
, &req
)) {
2088 /* Need to wait for migration thread (might exit: take ref). */
2089 struct task_struct
*mt
= rq
->migration_thread
;
2091 get_task_struct(mt
);
2092 task_rq_unlock(rq
, &flags
);
2093 wake_up_process(mt
);
2094 put_task_struct(mt
);
2095 wait_for_completion(&req
.done
);
2100 task_rq_unlock(rq
, &flags
);
2104 * sched_exec - execve() is a valuable balancing opportunity, because at
2105 * this point the task has the smallest effective memory and cache footprint.
2107 void sched_exec(void)
2109 int new_cpu
, this_cpu
= get_cpu();
2110 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2112 if (new_cpu
!= this_cpu
)
2113 sched_migrate_task(current
, new_cpu
);
2117 * pull_task - move a task from a remote runqueue to the local runqueue.
2118 * Both runqueues must be locked.
2120 static void pull_task(struct rq
*src_rq
, struct task_struct
*p
,
2121 struct rq
*this_rq
, int this_cpu
)
2123 deactivate_task(src_rq
, p
, 0);
2124 set_task_cpu(p
, this_cpu
);
2125 activate_task(this_rq
, p
, 0);
2127 * Note that idle threads have a prio of MAX_PRIO, for this test
2128 * to be always true for them.
2130 check_preempt_curr(this_rq
, p
);
2134 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2137 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2138 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2142 * We do not migrate tasks that are:
2143 * 1) running (obviously), or
2144 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2145 * 3) are cache-hot on their current CPU.
2147 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
2151 if (task_running(rq
, p
))
2157 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2158 unsigned long max_nr_move
, unsigned long max_load_move
,
2159 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2160 int *all_pinned
, unsigned long *load_moved
,
2161 int *this_best_prio
, struct rq_iterator
*iterator
)
2163 int pulled
= 0, pinned
= 0, skip_for_load
;
2164 struct task_struct
*p
;
2165 long rem_load_move
= max_load_move
;
2167 if (max_nr_move
== 0 || max_load_move
== 0)
2173 * Start the load-balancing iterator:
2175 p
= iterator
->start(iterator
->arg
);
2180 * To help distribute high priority tasks accross CPUs we don't
2181 * skip a task if it will be the highest priority task (i.e. smallest
2182 * prio value) on its new queue regardless of its load weight
2184 skip_for_load
= (p
->se
.load
.weight
>> 1) > rem_load_move
+
2185 SCHED_LOAD_SCALE_FUZZ
;
2186 if ((skip_for_load
&& p
->prio
>= *this_best_prio
) ||
2187 !can_migrate_task(p
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2188 p
= iterator
->next(iterator
->arg
);
2192 pull_task(busiest
, p
, this_rq
, this_cpu
);
2194 rem_load_move
-= p
->se
.load
.weight
;
2197 * We only want to steal up to the prescribed number of tasks
2198 * and the prescribed amount of weighted load.
2200 if (pulled
< max_nr_move
&& rem_load_move
> 0) {
2201 if (p
->prio
< *this_best_prio
)
2202 *this_best_prio
= p
->prio
;
2203 p
= iterator
->next(iterator
->arg
);
2208 * Right now, this is the only place pull_task() is called,
2209 * so we can safely collect pull_task() stats here rather than
2210 * inside pull_task().
2212 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2215 *all_pinned
= pinned
;
2216 *load_moved
= max_load_move
- rem_load_move
;
2221 * move_tasks tries to move up to max_load_move weighted load from busiest to
2222 * this_rq, as part of a balancing operation within domain "sd".
2223 * Returns 1 if successful and 0 otherwise.
2225 * Called with both runqueues locked.
2227 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2228 unsigned long max_load_move
,
2229 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2232 struct sched_class
*class = sched_class_highest
;
2233 unsigned long total_load_moved
= 0;
2234 int this_best_prio
= this_rq
->curr
->prio
;
2238 class->load_balance(this_rq
, this_cpu
, busiest
,
2239 ULONG_MAX
, max_load_move
- total_load_moved
,
2240 sd
, idle
, all_pinned
, &this_best_prio
);
2241 class = class->next
;
2242 } while (class && max_load_move
> total_load_moved
);
2244 return total_load_moved
> 0;
2248 * move_one_task tries to move exactly one task from busiest to this_rq, as
2249 * part of active balancing operations within "domain".
2250 * Returns 1 if successful and 0 otherwise.
2252 * Called with both runqueues locked.
2254 static int move_one_task(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2255 struct sched_domain
*sd
, enum cpu_idle_type idle
)
2257 struct sched_class
*class;
2258 int this_best_prio
= MAX_PRIO
;
2260 for (class = sched_class_highest
; class; class = class->next
)
2261 if (class->load_balance(this_rq
, this_cpu
, busiest
,
2262 1, ULONG_MAX
, sd
, idle
, NULL
,
2270 * find_busiest_group finds and returns the busiest CPU group within the
2271 * domain. It calculates and returns the amount of weighted load which
2272 * should be moved to restore balance via the imbalance parameter.
2274 static struct sched_group
*
2275 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2276 unsigned long *imbalance
, enum cpu_idle_type idle
,
2277 int *sd_idle
, cpumask_t
*cpus
, int *balance
)
2279 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2280 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2281 unsigned long max_pull
;
2282 unsigned long busiest_load_per_task
, busiest_nr_running
;
2283 unsigned long this_load_per_task
, this_nr_running
;
2285 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2286 int power_savings_balance
= 1;
2287 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2288 unsigned long min_nr_running
= ULONG_MAX
;
2289 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2292 max_load
= this_load
= total_load
= total_pwr
= 0;
2293 busiest_load_per_task
= busiest_nr_running
= 0;
2294 this_load_per_task
= this_nr_running
= 0;
2295 if (idle
== CPU_NOT_IDLE
)
2296 load_idx
= sd
->busy_idx
;
2297 else if (idle
== CPU_NEWLY_IDLE
)
2298 load_idx
= sd
->newidle_idx
;
2300 load_idx
= sd
->idle_idx
;
2303 unsigned long load
, group_capacity
;
2306 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2307 unsigned long sum_nr_running
, sum_weighted_load
;
2309 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2312 balance_cpu
= first_cpu(group
->cpumask
);
2314 /* Tally up the load of all CPUs in the group */
2315 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2317 for_each_cpu_mask(i
, group
->cpumask
) {
2320 if (!cpu_isset(i
, *cpus
))
2325 if (*sd_idle
&& rq
->nr_running
)
2328 /* Bias balancing toward cpus of our domain */
2330 if (idle_cpu(i
) && !first_idle_cpu
) {
2335 load
= target_load(i
, load_idx
);
2337 load
= source_load(i
, load_idx
);
2340 sum_nr_running
+= rq
->nr_running
;
2341 sum_weighted_load
+= weighted_cpuload(i
);
2345 * First idle cpu or the first cpu(busiest) in this sched group
2346 * is eligible for doing load balancing at this and above
2347 * domains. In the newly idle case, we will allow all the cpu's
2348 * to do the newly idle load balance.
2350 if (idle
!= CPU_NEWLY_IDLE
&& local_group
&&
2351 balance_cpu
!= this_cpu
&& balance
) {
2356 total_load
+= avg_load
;
2357 total_pwr
+= group
->__cpu_power
;
2359 /* Adjust by relative CPU power of the group */
2360 avg_load
= sg_div_cpu_power(group
,
2361 avg_load
* SCHED_LOAD_SCALE
);
2363 group_capacity
= group
->__cpu_power
/ SCHED_LOAD_SCALE
;
2366 this_load
= avg_load
;
2368 this_nr_running
= sum_nr_running
;
2369 this_load_per_task
= sum_weighted_load
;
2370 } else if (avg_load
> max_load
&&
2371 sum_nr_running
> group_capacity
) {
2372 max_load
= avg_load
;
2374 busiest_nr_running
= sum_nr_running
;
2375 busiest_load_per_task
= sum_weighted_load
;
2378 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2380 * Busy processors will not participate in power savings
2383 if (idle
== CPU_NOT_IDLE
||
2384 !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2388 * If the local group is idle or completely loaded
2389 * no need to do power savings balance at this domain
2391 if (local_group
&& (this_nr_running
>= group_capacity
||
2393 power_savings_balance
= 0;
2396 * If a group is already running at full capacity or idle,
2397 * don't include that group in power savings calculations
2399 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2404 * Calculate the group which has the least non-idle load.
2405 * This is the group from where we need to pick up the load
2408 if ((sum_nr_running
< min_nr_running
) ||
2409 (sum_nr_running
== min_nr_running
&&
2410 first_cpu(group
->cpumask
) <
2411 first_cpu(group_min
->cpumask
))) {
2413 min_nr_running
= sum_nr_running
;
2414 min_load_per_task
= sum_weighted_load
/
2419 * Calculate the group which is almost near its
2420 * capacity but still has some space to pick up some load
2421 * from other group and save more power
2423 if (sum_nr_running
<= group_capacity
- 1) {
2424 if (sum_nr_running
> leader_nr_running
||
2425 (sum_nr_running
== leader_nr_running
&&
2426 first_cpu(group
->cpumask
) >
2427 first_cpu(group_leader
->cpumask
))) {
2428 group_leader
= group
;
2429 leader_nr_running
= sum_nr_running
;
2434 group
= group
->next
;
2435 } while (group
!= sd
->groups
);
2437 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2440 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2442 if (this_load
>= avg_load
||
2443 100*max_load
<= sd
->imbalance_pct
*this_load
)
2446 busiest_load_per_task
/= busiest_nr_running
;
2448 * We're trying to get all the cpus to the average_load, so we don't
2449 * want to push ourselves above the average load, nor do we wish to
2450 * reduce the max loaded cpu below the average load, as either of these
2451 * actions would just result in more rebalancing later, and ping-pong
2452 * tasks around. Thus we look for the minimum possible imbalance.
2453 * Negative imbalances (*we* are more loaded than anyone else) will
2454 * be counted as no imbalance for these purposes -- we can't fix that
2455 * by pulling tasks to us. Be careful of negative numbers as they'll
2456 * appear as very large values with unsigned longs.
2458 if (max_load
<= busiest_load_per_task
)
2462 * In the presence of smp nice balancing, certain scenarios can have
2463 * max load less than avg load(as we skip the groups at or below
2464 * its cpu_power, while calculating max_load..)
2466 if (max_load
< avg_load
) {
2468 goto small_imbalance
;
2471 /* Don't want to pull so many tasks that a group would go idle */
2472 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2474 /* How much load to actually move to equalise the imbalance */
2475 *imbalance
= min(max_pull
* busiest
->__cpu_power
,
2476 (avg_load
- this_load
) * this->__cpu_power
)
2480 * if *imbalance is less than the average load per runnable task
2481 * there is no gaurantee that any tasks will be moved so we'll have
2482 * a think about bumping its value to force at least one task to be
2485 if (*imbalance
< busiest_load_per_task
) {
2486 unsigned long tmp
, pwr_now
, pwr_move
;
2490 pwr_move
= pwr_now
= 0;
2492 if (this_nr_running
) {
2493 this_load_per_task
/= this_nr_running
;
2494 if (busiest_load_per_task
> this_load_per_task
)
2497 this_load_per_task
= SCHED_LOAD_SCALE
;
2499 if (max_load
- this_load
+ SCHED_LOAD_SCALE_FUZZ
>=
2500 busiest_load_per_task
* imbn
) {
2501 *imbalance
= busiest_load_per_task
;
2506 * OK, we don't have enough imbalance to justify moving tasks,
2507 * however we may be able to increase total CPU power used by
2511 pwr_now
+= busiest
->__cpu_power
*
2512 min(busiest_load_per_task
, max_load
);
2513 pwr_now
+= this->__cpu_power
*
2514 min(this_load_per_task
, this_load
);
2515 pwr_now
/= SCHED_LOAD_SCALE
;
2517 /* Amount of load we'd subtract */
2518 tmp
= sg_div_cpu_power(busiest
,
2519 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2521 pwr_move
+= busiest
->__cpu_power
*
2522 min(busiest_load_per_task
, max_load
- tmp
);
2524 /* Amount of load we'd add */
2525 if (max_load
* busiest
->__cpu_power
<
2526 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2527 tmp
= sg_div_cpu_power(this,
2528 max_load
* busiest
->__cpu_power
);
2530 tmp
= sg_div_cpu_power(this,
2531 busiest_load_per_task
* SCHED_LOAD_SCALE
);
2532 pwr_move
+= this->__cpu_power
*
2533 min(this_load_per_task
, this_load
+ tmp
);
2534 pwr_move
/= SCHED_LOAD_SCALE
;
2536 /* Move if we gain throughput */
2537 if (pwr_move
> pwr_now
)
2538 *imbalance
= busiest_load_per_task
;
2544 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2545 if (idle
== CPU_NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2548 if (this == group_leader
&& group_leader
!= group_min
) {
2549 *imbalance
= min_load_per_task
;
2559 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2562 find_busiest_queue(struct sched_group
*group
, enum cpu_idle_type idle
,
2563 unsigned long imbalance
, cpumask_t
*cpus
)
2565 struct rq
*busiest
= NULL
, *rq
;
2566 unsigned long max_load
= 0;
2569 for_each_cpu_mask(i
, group
->cpumask
) {
2572 if (!cpu_isset(i
, *cpus
))
2576 wl
= weighted_cpuload(i
);
2578 if (rq
->nr_running
== 1 && wl
> imbalance
)
2581 if (wl
> max_load
) {
2591 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2592 * so long as it is large enough.
2594 #define MAX_PINNED_INTERVAL 512
2597 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2598 * tasks if there is an imbalance.
2600 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2601 struct sched_domain
*sd
, enum cpu_idle_type idle
,
2604 int ld_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2605 struct sched_group
*group
;
2606 unsigned long imbalance
;
2608 cpumask_t cpus
= CPU_MASK_ALL
;
2609 unsigned long flags
;
2612 * When power savings policy is enabled for the parent domain, idle
2613 * sibling can pick up load irrespective of busy siblings. In this case,
2614 * let the state of idle sibling percolate up as CPU_IDLE, instead of
2615 * portraying it as CPU_NOT_IDLE.
2617 if (idle
!= CPU_NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2618 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2621 schedstat_inc(sd
, lb_cnt
[idle
]);
2624 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2631 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2635 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2637 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2641 BUG_ON(busiest
== this_rq
);
2643 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2646 if (busiest
->nr_running
> 1) {
2648 * Attempt to move tasks. If find_busiest_group has found
2649 * an imbalance but busiest->nr_running <= 1, the group is
2650 * still unbalanced. ld_moved simply stays zero, so it is
2651 * correctly treated as an imbalance.
2653 local_irq_save(flags
);
2654 double_rq_lock(this_rq
, busiest
);
2655 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2656 imbalance
, sd
, idle
, &all_pinned
);
2657 double_rq_unlock(this_rq
, busiest
);
2658 local_irq_restore(flags
);
2661 * some other cpu did the load balance for us.
2663 if (ld_moved
&& this_cpu
!= smp_processor_id())
2664 resched_cpu(this_cpu
);
2666 /* All tasks on this runqueue were pinned by CPU affinity */
2667 if (unlikely(all_pinned
)) {
2668 cpu_clear(cpu_of(busiest
), cpus
);
2669 if (!cpus_empty(cpus
))
2676 schedstat_inc(sd
, lb_failed
[idle
]);
2677 sd
->nr_balance_failed
++;
2679 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2681 spin_lock_irqsave(&busiest
->lock
, flags
);
2683 /* don't kick the migration_thread, if the curr
2684 * task on busiest cpu can't be moved to this_cpu
2686 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2687 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2689 goto out_one_pinned
;
2692 if (!busiest
->active_balance
) {
2693 busiest
->active_balance
= 1;
2694 busiest
->push_cpu
= this_cpu
;
2697 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2699 wake_up_process(busiest
->migration_thread
);
2702 * We've kicked active balancing, reset the failure
2705 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2708 sd
->nr_balance_failed
= 0;
2710 if (likely(!active_balance
)) {
2711 /* We were unbalanced, so reset the balancing interval */
2712 sd
->balance_interval
= sd
->min_interval
;
2715 * If we've begun active balancing, start to back off. This
2716 * case may not be covered by the all_pinned logic if there
2717 * is only 1 task on the busy runqueue (because we don't call
2720 if (sd
->balance_interval
< sd
->max_interval
)
2721 sd
->balance_interval
*= 2;
2724 if (!ld_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2725 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2730 schedstat_inc(sd
, lb_balanced
[idle
]);
2732 sd
->nr_balance_failed
= 0;
2735 /* tune up the balancing interval */
2736 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2737 (sd
->balance_interval
< sd
->max_interval
))
2738 sd
->balance_interval
*= 2;
2740 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2741 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2747 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2748 * tasks if there is an imbalance.
2750 * Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
2751 * this_rq is locked.
2754 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2756 struct sched_group
*group
;
2757 struct rq
*busiest
= NULL
;
2758 unsigned long imbalance
;
2762 cpumask_t cpus
= CPU_MASK_ALL
;
2765 * When power savings policy is enabled for the parent domain, idle
2766 * sibling can pick up load irrespective of busy siblings. In this case,
2767 * let the state of idle sibling percolate up as IDLE, instead of
2768 * portraying it as CPU_NOT_IDLE.
2770 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2771 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2774 schedstat_inc(sd
, lb_cnt
[CPU_NEWLY_IDLE
]);
2776 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, CPU_NEWLY_IDLE
,
2777 &sd_idle
, &cpus
, NULL
);
2779 schedstat_inc(sd
, lb_nobusyg
[CPU_NEWLY_IDLE
]);
2783 busiest
= find_busiest_queue(group
, CPU_NEWLY_IDLE
, imbalance
,
2786 schedstat_inc(sd
, lb_nobusyq
[CPU_NEWLY_IDLE
]);
2790 BUG_ON(busiest
== this_rq
);
2792 schedstat_add(sd
, lb_imbalance
[CPU_NEWLY_IDLE
], imbalance
);
2795 if (busiest
->nr_running
> 1) {
2796 /* Attempt to move tasks */
2797 double_lock_balance(this_rq
, busiest
);
2798 /* this_rq->clock is already updated */
2799 update_rq_clock(busiest
);
2800 ld_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2801 imbalance
, sd
, CPU_NEWLY_IDLE
,
2803 spin_unlock(&busiest
->lock
);
2805 if (unlikely(all_pinned
)) {
2806 cpu_clear(cpu_of(busiest
), cpus
);
2807 if (!cpus_empty(cpus
))
2813 schedstat_inc(sd
, lb_failed
[CPU_NEWLY_IDLE
]);
2814 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2815 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2818 sd
->nr_balance_failed
= 0;
2823 schedstat_inc(sd
, lb_balanced
[CPU_NEWLY_IDLE
]);
2824 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2825 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2827 sd
->nr_balance_failed
= 0;
2833 * idle_balance is called by schedule() if this_cpu is about to become
2834 * idle. Attempts to pull tasks from other CPUs.
2836 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2838 struct sched_domain
*sd
;
2839 int pulled_task
= -1;
2840 unsigned long next_balance
= jiffies
+ HZ
;
2842 for_each_domain(this_cpu
, sd
) {
2843 unsigned long interval
;
2845 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2848 if (sd
->flags
& SD_BALANCE_NEWIDLE
)
2849 /* If we've pulled tasks over stop searching: */
2850 pulled_task
= load_balance_newidle(this_cpu
,
2853 interval
= msecs_to_jiffies(sd
->balance_interval
);
2854 if (time_after(next_balance
, sd
->last_balance
+ interval
))
2855 next_balance
= sd
->last_balance
+ interval
;
2859 if (pulled_task
|| time_after(jiffies
, this_rq
->next_balance
)) {
2861 * We are going idle. next_balance may be set based on
2862 * a busy processor. So reset next_balance.
2864 this_rq
->next_balance
= next_balance
;
2869 * active_load_balance is run by migration threads. It pushes running tasks
2870 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2871 * running on each physical CPU where possible, and avoids physical /
2872 * logical imbalances.
2874 * Called with busiest_rq locked.
2876 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
2878 int target_cpu
= busiest_rq
->push_cpu
;
2879 struct sched_domain
*sd
;
2880 struct rq
*target_rq
;
2882 /* Is there any task to move? */
2883 if (busiest_rq
->nr_running
<= 1)
2886 target_rq
= cpu_rq(target_cpu
);
2889 * This condition is "impossible", if it occurs
2890 * we need to fix it. Originally reported by
2891 * Bjorn Helgaas on a 128-cpu setup.
2893 BUG_ON(busiest_rq
== target_rq
);
2895 /* move a task from busiest_rq to target_rq */
2896 double_lock_balance(busiest_rq
, target_rq
);
2897 update_rq_clock(busiest_rq
);
2898 update_rq_clock(target_rq
);
2900 /* Search for an sd spanning us and the target CPU. */
2901 for_each_domain(target_cpu
, sd
) {
2902 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2903 cpu_isset(busiest_cpu
, sd
->span
))
2908 schedstat_inc(sd
, alb_cnt
);
2910 if (move_one_task(target_rq
, target_cpu
, busiest_rq
,
2912 schedstat_inc(sd
, alb_pushed
);
2914 schedstat_inc(sd
, alb_failed
);
2916 spin_unlock(&target_rq
->lock
);
2921 atomic_t load_balancer
;
2923 } nohz ____cacheline_aligned
= {
2924 .load_balancer
= ATOMIC_INIT(-1),
2925 .cpu_mask
= CPU_MASK_NONE
,
2929 * This routine will try to nominate the ilb (idle load balancing)
2930 * owner among the cpus whose ticks are stopped. ilb owner will do the idle
2931 * load balancing on behalf of all those cpus. If all the cpus in the system
2932 * go into this tickless mode, then there will be no ilb owner (as there is
2933 * no need for one) and all the cpus will sleep till the next wakeup event
2936 * For the ilb owner, tick is not stopped. And this tick will be used
2937 * for idle load balancing. ilb owner will still be part of
2940 * While stopping the tick, this cpu will become the ilb owner if there
2941 * is no other owner. And will be the owner till that cpu becomes busy
2942 * or if all cpus in the system stop their ticks at which point
2943 * there is no need for ilb owner.
2945 * When the ilb owner becomes busy, it nominates another owner, during the
2946 * next busy scheduler_tick()
2948 int select_nohz_load_balancer(int stop_tick
)
2950 int cpu
= smp_processor_id();
2953 cpu_set(cpu
, nohz
.cpu_mask
);
2954 cpu_rq(cpu
)->in_nohz_recently
= 1;
2957 * If we are going offline and still the leader, give up!
2959 if (cpu_is_offline(cpu
) &&
2960 atomic_read(&nohz
.load_balancer
) == cpu
) {
2961 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
2966 /* time for ilb owner also to sleep */
2967 if (cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
2968 if (atomic_read(&nohz
.load_balancer
) == cpu
)
2969 atomic_set(&nohz
.load_balancer
, -1);
2973 if (atomic_read(&nohz
.load_balancer
) == -1) {
2974 /* make me the ilb owner */
2975 if (atomic_cmpxchg(&nohz
.load_balancer
, -1, cpu
) == -1)
2977 } else if (atomic_read(&nohz
.load_balancer
) == cpu
)
2980 if (!cpu_isset(cpu
, nohz
.cpu_mask
))
2983 cpu_clear(cpu
, nohz
.cpu_mask
);
2985 if (atomic_read(&nohz
.load_balancer
) == cpu
)
2986 if (atomic_cmpxchg(&nohz
.load_balancer
, cpu
, -1) != cpu
)
2993 static DEFINE_SPINLOCK(balancing
);
2996 * It checks each scheduling domain to see if it is due to be balanced,
2997 * and initiates a balancing operation if so.
2999 * Balancing parameters are set up in arch_init_sched_domains.
3001 static inline void rebalance_domains(int cpu
, enum cpu_idle_type idle
)
3004 struct rq
*rq
= cpu_rq(cpu
);
3005 unsigned long interval
;
3006 struct sched_domain
*sd
;
3007 /* Earliest time when we have to do rebalance again */
3008 unsigned long next_balance
= jiffies
+ 60*HZ
;
3009 int update_next_balance
= 0;
3011 for_each_domain(cpu
, sd
) {
3012 if (!(sd
->flags
& SD_LOAD_BALANCE
))
3015 interval
= sd
->balance_interval
;
3016 if (idle
!= CPU_IDLE
)
3017 interval
*= sd
->busy_factor
;
3019 /* scale ms to jiffies */
3020 interval
= msecs_to_jiffies(interval
);
3021 if (unlikely(!interval
))
3023 if (interval
> HZ
*NR_CPUS
/10)
3024 interval
= HZ
*NR_CPUS
/10;
3027 if (sd
->flags
& SD_SERIALIZE
) {
3028 if (!spin_trylock(&balancing
))
3032 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
3033 if (load_balance(cpu
, rq
, sd
, idle
, &balance
)) {
3035 * We've pulled tasks over so either we're no
3036 * longer idle, or one of our SMT siblings is
3039 idle
= CPU_NOT_IDLE
;
3041 sd
->last_balance
= jiffies
;
3043 if (sd
->flags
& SD_SERIALIZE
)
3044 spin_unlock(&balancing
);
3046 if (time_after(next_balance
, sd
->last_balance
+ interval
)) {
3047 next_balance
= sd
->last_balance
+ interval
;
3048 update_next_balance
= 1;
3052 * Stop the load balance at this level. There is another
3053 * CPU in our sched group which is doing load balancing more
3061 * next_balance will be updated only when there is a need.
3062 * When the cpu is attached to null domain for ex, it will not be
3065 if (likely(update_next_balance
))
3066 rq
->next_balance
= next_balance
;
3070 * run_rebalance_domains is triggered when needed from the scheduler tick.
3071 * In CONFIG_NO_HZ case, the idle load balance owner will do the
3072 * rebalancing for all the cpus for whom scheduler ticks are stopped.
3074 static void run_rebalance_domains(struct softirq_action
*h
)
3076 int this_cpu
= smp_processor_id();
3077 struct rq
*this_rq
= cpu_rq(this_cpu
);
3078 enum cpu_idle_type idle
= this_rq
->idle_at_tick
?
3079 CPU_IDLE
: CPU_NOT_IDLE
;
3081 rebalance_domains(this_cpu
, idle
);
3085 * If this cpu is the owner for idle load balancing, then do the
3086 * balancing on behalf of the other idle cpus whose ticks are
3089 if (this_rq
->idle_at_tick
&&
3090 atomic_read(&nohz
.load_balancer
) == this_cpu
) {
3091 cpumask_t cpus
= nohz
.cpu_mask
;
3095 cpu_clear(this_cpu
, cpus
);
3096 for_each_cpu_mask(balance_cpu
, cpus
) {
3098 * If this cpu gets work to do, stop the load balancing
3099 * work being done for other cpus. Next load
3100 * balancing owner will pick it up.
3105 rebalance_domains(balance_cpu
, CPU_IDLE
);
3107 rq
= cpu_rq(balance_cpu
);
3108 if (time_after(this_rq
->next_balance
, rq
->next_balance
))
3109 this_rq
->next_balance
= rq
->next_balance
;
3116 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
3118 * In case of CONFIG_NO_HZ, this is the place where we nominate a new
3119 * idle load balancing owner or decide to stop the periodic load balancing,
3120 * if the whole system is idle.
3122 static inline void trigger_load_balance(struct rq
*rq
, int cpu
)
3126 * If we were in the nohz mode recently and busy at the current
3127 * scheduler tick, then check if we need to nominate new idle
3130 if (rq
->in_nohz_recently
&& !rq
->idle_at_tick
) {
3131 rq
->in_nohz_recently
= 0;
3133 if (atomic_read(&nohz
.load_balancer
) == cpu
) {
3134 cpu_clear(cpu
, nohz
.cpu_mask
);
3135 atomic_set(&nohz
.load_balancer
, -1);
3138 if (atomic_read(&nohz
.load_balancer
) == -1) {
3140 * simple selection for now: Nominate the
3141 * first cpu in the nohz list to be the next
3144 * TBD: Traverse the sched domains and nominate
3145 * the nearest cpu in the nohz.cpu_mask.
3147 int ilb
= first_cpu(nohz
.cpu_mask
);
3155 * If this cpu is idle and doing idle load balancing for all the
3156 * cpus with ticks stopped, is it time for that to stop?
3158 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) == cpu
&&
3159 cpus_weight(nohz
.cpu_mask
) == num_online_cpus()) {
3165 * If this cpu is idle and the idle load balancing is done by
3166 * someone else, then no need raise the SCHED_SOFTIRQ
3168 if (rq
->idle_at_tick
&& atomic_read(&nohz
.load_balancer
) != cpu
&&
3169 cpu_isset(cpu
, nohz
.cpu_mask
))
3172 if (time_after_eq(jiffies
, rq
->next_balance
))
3173 raise_softirq(SCHED_SOFTIRQ
);
3176 #else /* CONFIG_SMP */
3179 * on UP we do not need to balance between CPUs:
3181 static inline void idle_balance(int cpu
, struct rq
*rq
)
3185 /* Avoid "used but not defined" warning on UP */
3186 static int balance_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
3187 unsigned long max_nr_move
, unsigned long max_load_move
,
3188 struct sched_domain
*sd
, enum cpu_idle_type idle
,
3189 int *all_pinned
, unsigned long *load_moved
,
3190 int *this_best_prio
, struct rq_iterator
*iterator
)
3199 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3201 EXPORT_PER_CPU_SYMBOL(kstat
);
3204 * Return p->sum_exec_runtime plus any more ns on the sched_clock
3205 * that have not yet been banked in case the task is currently running.
3207 unsigned long long task_sched_runtime(struct task_struct
*p
)
3209 unsigned long flags
;
3213 rq
= task_rq_lock(p
, &flags
);
3214 ns
= p
->se
.sum_exec_runtime
;
3215 if (rq
->curr
== p
) {
3216 update_rq_clock(rq
);
3217 delta_exec
= rq
->clock
- p
->se
.exec_start
;
3218 if ((s64
)delta_exec
> 0)
3221 task_rq_unlock(rq
, &flags
);
3227 * Account user cpu time to a process.
3228 * @p: the process that the cpu time gets accounted to
3229 * @hardirq_offset: the offset to subtract from hardirq_count()
3230 * @cputime: the cpu time spent in user space since the last update
3232 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3234 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3237 p
->utime
= cputime_add(p
->utime
, cputime
);
3239 /* Add user time to cpustat. */
3240 tmp
= cputime_to_cputime64(cputime
);
3241 if (TASK_NICE(p
) > 0)
3242 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3244 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3248 * Account system cpu time to a process.
3249 * @p: the process that the cpu time gets accounted to
3250 * @hardirq_offset: the offset to subtract from hardirq_count()
3251 * @cputime: the cpu time spent in kernel space since the last update
3253 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3256 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3257 struct rq
*rq
= this_rq();
3260 p
->stime
= cputime_add(p
->stime
, cputime
);
3262 /* Add system time to cpustat. */
3263 tmp
= cputime_to_cputime64(cputime
);
3264 if (hardirq_count() - hardirq_offset
)
3265 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3266 else if (softirq_count())
3267 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3268 else if (p
!= rq
->idle
)
3269 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3270 else if (atomic_read(&rq
->nr_iowait
) > 0)
3271 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3273 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3274 /* Account for system time used */
3275 acct_update_integrals(p
);
3279 * Account for involuntary wait time.
3280 * @p: the process from which the cpu time has been stolen
3281 * @steal: the cpu time spent in involuntary wait
3283 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3285 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3286 cputime64_t tmp
= cputime_to_cputime64(steal
);
3287 struct rq
*rq
= this_rq();
3289 if (p
== rq
->idle
) {
3290 p
->stime
= cputime_add(p
->stime
, steal
);
3291 if (atomic_read(&rq
->nr_iowait
) > 0)
3292 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3294 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3296 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3300 * This function gets called by the timer code, with HZ frequency.
3301 * We call it with interrupts disabled.
3303 * It also gets called by the fork code, when changing the parent's
3306 void scheduler_tick(void)
3308 int cpu
= smp_processor_id();
3309 struct rq
*rq
= cpu_rq(cpu
);
3310 struct task_struct
*curr
= rq
->curr
;
3311 u64 next_tick
= rq
->tick_timestamp
+ TICK_NSEC
;
3313 spin_lock(&rq
->lock
);
3314 __update_rq_clock(rq
);
3316 * Let rq->clock advance by at least TICK_NSEC:
3318 if (unlikely(rq
->clock
< next_tick
))
3319 rq
->clock
= next_tick
;
3320 rq
->tick_timestamp
= rq
->clock
;
3321 update_cpu_load(rq
);
3322 if (curr
!= rq
->idle
) /* FIXME: needed? */
3323 curr
->sched_class
->task_tick(rq
, curr
);
3324 spin_unlock(&rq
->lock
);
3327 rq
->idle_at_tick
= idle_cpu(cpu
);
3328 trigger_load_balance(rq
, cpu
);
3332 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3334 void fastcall
add_preempt_count(int val
)
3339 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3341 preempt_count() += val
;
3343 * Spinlock count overflowing soon?
3345 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3348 EXPORT_SYMBOL(add_preempt_count
);
3350 void fastcall
sub_preempt_count(int val
)
3355 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3358 * Is the spinlock portion underflowing?
3360 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3361 !(preempt_count() & PREEMPT_MASK
)))
3364 preempt_count() -= val
;
3366 EXPORT_SYMBOL(sub_preempt_count
);
3371 * Print scheduling while atomic bug:
3373 static noinline
void __schedule_bug(struct task_struct
*prev
)
3375 printk(KERN_ERR
"BUG: scheduling while atomic: %s/0x%08x/%d\n",
3376 prev
->comm
, preempt_count(), prev
->pid
);
3377 debug_show_held_locks(prev
);
3378 if (irqs_disabled())
3379 print_irqtrace_events(prev
);
3384 * Various schedule()-time debugging checks and statistics:
3386 static inline void schedule_debug(struct task_struct
*prev
)
3389 * Test if we are atomic. Since do_exit() needs to call into
3390 * schedule() atomically, we ignore that path for now.
3391 * Otherwise, whine if we are scheduling when we should not be.
3393 if (unlikely(in_atomic_preempt_off()) && unlikely(!prev
->exit_state
))
3394 __schedule_bug(prev
);
3396 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3398 schedstat_inc(this_rq(), sched_cnt
);
3402 * Pick up the highest-prio task:
3404 static inline struct task_struct
*
3405 pick_next_task(struct rq
*rq
, struct task_struct
*prev
)
3407 struct sched_class
*class;
3408 struct task_struct
*p
;
3411 * Optimization: we know that if all tasks are in
3412 * the fair class we can call that function directly:
3414 if (likely(rq
->nr_running
== rq
->cfs
.nr_running
)) {
3415 p
= fair_sched_class
.pick_next_task(rq
);
3420 class = sched_class_highest
;
3422 p
= class->pick_next_task(rq
);
3426 * Will never be NULL as the idle class always
3427 * returns a non-NULL p:
3429 class = class->next
;
3434 * schedule() is the main scheduler function.
3436 asmlinkage
void __sched
schedule(void)
3438 struct task_struct
*prev
, *next
;
3445 cpu
= smp_processor_id();
3449 switch_count
= &prev
->nivcsw
;
3451 release_kernel_lock(prev
);
3452 need_resched_nonpreemptible
:
3454 schedule_debug(prev
);
3456 spin_lock_irq(&rq
->lock
);
3457 clear_tsk_need_resched(prev
);
3458 __update_rq_clock(rq
);
3460 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3461 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3462 unlikely(signal_pending(prev
)))) {
3463 prev
->state
= TASK_RUNNING
;
3465 deactivate_task(rq
, prev
, 1);
3467 switch_count
= &prev
->nvcsw
;
3470 if (unlikely(!rq
->nr_running
))
3471 idle_balance(cpu
, rq
);
3473 prev
->sched_class
->put_prev_task(rq
, prev
);
3474 next
= pick_next_task(rq
, prev
);
3476 sched_info_switch(prev
, next
);
3478 if (likely(prev
!= next
)) {
3483 context_switch(rq
, prev
, next
); /* unlocks the rq */
3485 spin_unlock_irq(&rq
->lock
);
3487 if (unlikely(reacquire_kernel_lock(current
) < 0)) {
3488 cpu
= smp_processor_id();
3490 goto need_resched_nonpreemptible
;
3492 preempt_enable_no_resched();
3493 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3496 EXPORT_SYMBOL(schedule
);
3498 #ifdef CONFIG_PREEMPT
3500 * this is the entry point to schedule() from in-kernel preemption
3501 * off of preempt_enable. Kernel preemptions off return from interrupt
3502 * occur there and call schedule directly.
3504 asmlinkage
void __sched
preempt_schedule(void)
3506 struct thread_info
*ti
= current_thread_info();
3507 #ifdef CONFIG_PREEMPT_BKL
3508 struct task_struct
*task
= current
;
3509 int saved_lock_depth
;
3512 * If there is a non-zero preempt_count or interrupts are disabled,
3513 * we do not want to preempt the current task. Just return..
3515 if (likely(ti
->preempt_count
|| irqs_disabled()))
3519 add_preempt_count(PREEMPT_ACTIVE
);
3521 * We keep the big kernel semaphore locked, but we
3522 * clear ->lock_depth so that schedule() doesnt
3523 * auto-release the semaphore:
3525 #ifdef CONFIG_PREEMPT_BKL
3526 saved_lock_depth
= task
->lock_depth
;
3527 task
->lock_depth
= -1;
3530 #ifdef CONFIG_PREEMPT_BKL
3531 task
->lock_depth
= saved_lock_depth
;
3533 sub_preempt_count(PREEMPT_ACTIVE
);
3535 /* we could miss a preemption opportunity between schedule and now */
3537 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3540 EXPORT_SYMBOL(preempt_schedule
);
3543 * this is the entry point to schedule() from kernel preemption
3544 * off of irq context.
3545 * Note, that this is called and return with irqs disabled. This will
3546 * protect us against recursive calling from irq.
3548 asmlinkage
void __sched
preempt_schedule_irq(void)
3550 struct thread_info
*ti
= current_thread_info();
3551 #ifdef CONFIG_PREEMPT_BKL
3552 struct task_struct
*task
= current
;
3553 int saved_lock_depth
;
3555 /* Catch callers which need to be fixed */
3556 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3559 add_preempt_count(PREEMPT_ACTIVE
);
3561 * We keep the big kernel semaphore locked, but we
3562 * clear ->lock_depth so that schedule() doesnt
3563 * auto-release the semaphore:
3565 #ifdef CONFIG_PREEMPT_BKL
3566 saved_lock_depth
= task
->lock_depth
;
3567 task
->lock_depth
= -1;
3571 local_irq_disable();
3572 #ifdef CONFIG_PREEMPT_BKL
3573 task
->lock_depth
= saved_lock_depth
;
3575 sub_preempt_count(PREEMPT_ACTIVE
);
3577 /* we could miss a preemption opportunity between schedule and now */
3579 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3583 #endif /* CONFIG_PREEMPT */
3585 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3588 return try_to_wake_up(curr
->private, mode
, sync
);
3590 EXPORT_SYMBOL(default_wake_function
);
3593 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3594 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3595 * number) then we wake all the non-exclusive tasks and one exclusive task.
3597 * There are circumstances in which we can try to wake a task which has already
3598 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3599 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3601 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3602 int nr_exclusive
, int sync
, void *key
)
3604 wait_queue_t
*curr
, *next
;
3606 list_for_each_entry_safe(curr
, next
, &q
->task_list
, task_list
) {
3607 unsigned flags
= curr
->flags
;
3609 if (curr
->func(curr
, mode
, sync
, key
) &&
3610 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3616 * __wake_up - wake up threads blocked on a waitqueue.
3618 * @mode: which threads
3619 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3620 * @key: is directly passed to the wakeup function
3622 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3623 int nr_exclusive
, void *key
)
3625 unsigned long flags
;
3627 spin_lock_irqsave(&q
->lock
, flags
);
3628 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3629 spin_unlock_irqrestore(&q
->lock
, flags
);
3631 EXPORT_SYMBOL(__wake_up
);
3634 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3636 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3638 __wake_up_common(q
, mode
, 1, 0, NULL
);
3642 * __wake_up_sync - wake up threads blocked on a waitqueue.
3644 * @mode: which threads
3645 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3647 * The sync wakeup differs that the waker knows that it will schedule
3648 * away soon, so while the target thread will be woken up, it will not
3649 * be migrated to another CPU - ie. the two threads are 'synchronized'
3650 * with each other. This can prevent needless bouncing between CPUs.
3652 * On UP it can prevent extra preemption.
3655 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3657 unsigned long flags
;
3663 if (unlikely(!nr_exclusive
))
3666 spin_lock_irqsave(&q
->lock
, flags
);
3667 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3668 spin_unlock_irqrestore(&q
->lock
, flags
);
3670 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3672 void fastcall
complete(struct completion
*x
)
3674 unsigned long flags
;
3676 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3678 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3680 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3682 EXPORT_SYMBOL(complete
);
3684 void fastcall
complete_all(struct completion
*x
)
3686 unsigned long flags
;
3688 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3689 x
->done
+= UINT_MAX
/2;
3690 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3692 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3694 EXPORT_SYMBOL(complete_all
);
3696 void fastcall __sched
wait_for_completion(struct completion
*x
)
3700 spin_lock_irq(&x
->wait
.lock
);
3702 DECLARE_WAITQUEUE(wait
, current
);
3704 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3705 __add_wait_queue_tail(&x
->wait
, &wait
);
3707 __set_current_state(TASK_UNINTERRUPTIBLE
);
3708 spin_unlock_irq(&x
->wait
.lock
);
3710 spin_lock_irq(&x
->wait
.lock
);
3712 __remove_wait_queue(&x
->wait
, &wait
);
3715 spin_unlock_irq(&x
->wait
.lock
);
3717 EXPORT_SYMBOL(wait_for_completion
);
3719 unsigned long fastcall __sched
3720 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3724 spin_lock_irq(&x
->wait
.lock
);
3726 DECLARE_WAITQUEUE(wait
, current
);
3728 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3729 __add_wait_queue_tail(&x
->wait
, &wait
);
3731 __set_current_state(TASK_UNINTERRUPTIBLE
);
3732 spin_unlock_irq(&x
->wait
.lock
);
3733 timeout
= schedule_timeout(timeout
);
3734 spin_lock_irq(&x
->wait
.lock
);
3736 __remove_wait_queue(&x
->wait
, &wait
);
3740 __remove_wait_queue(&x
->wait
, &wait
);
3744 spin_unlock_irq(&x
->wait
.lock
);
3747 EXPORT_SYMBOL(wait_for_completion_timeout
);
3749 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3755 spin_lock_irq(&x
->wait
.lock
);
3757 DECLARE_WAITQUEUE(wait
, current
);
3759 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3760 __add_wait_queue_tail(&x
->wait
, &wait
);
3762 if (signal_pending(current
)) {
3764 __remove_wait_queue(&x
->wait
, &wait
);
3767 __set_current_state(TASK_INTERRUPTIBLE
);
3768 spin_unlock_irq(&x
->wait
.lock
);
3770 spin_lock_irq(&x
->wait
.lock
);
3772 __remove_wait_queue(&x
->wait
, &wait
);
3776 spin_unlock_irq(&x
->wait
.lock
);
3780 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3782 unsigned long fastcall __sched
3783 wait_for_completion_interruptible_timeout(struct completion
*x
,
3784 unsigned long timeout
)
3788 spin_lock_irq(&x
->wait
.lock
);
3790 DECLARE_WAITQUEUE(wait
, current
);
3792 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3793 __add_wait_queue_tail(&x
->wait
, &wait
);
3795 if (signal_pending(current
)) {
3796 timeout
= -ERESTARTSYS
;
3797 __remove_wait_queue(&x
->wait
, &wait
);
3800 __set_current_state(TASK_INTERRUPTIBLE
);
3801 spin_unlock_irq(&x
->wait
.lock
);
3802 timeout
= schedule_timeout(timeout
);
3803 spin_lock_irq(&x
->wait
.lock
);
3805 __remove_wait_queue(&x
->wait
, &wait
);
3809 __remove_wait_queue(&x
->wait
, &wait
);
3813 spin_unlock_irq(&x
->wait
.lock
);
3816 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3819 sleep_on_head(wait_queue_head_t
*q
, wait_queue_t
*wait
, unsigned long *flags
)
3821 spin_lock_irqsave(&q
->lock
, *flags
);
3822 __add_wait_queue(q
, wait
);
3823 spin_unlock(&q
->lock
);
3827 sleep_on_tail(wait_queue_head_t
*q
, wait_queue_t
*wait
, unsigned long *flags
)
3829 spin_lock_irq(&q
->lock
);
3830 __remove_wait_queue(q
, wait
);
3831 spin_unlock_irqrestore(&q
->lock
, *flags
);
3834 void __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3836 unsigned long flags
;
3839 init_waitqueue_entry(&wait
, current
);
3841 current
->state
= TASK_INTERRUPTIBLE
;
3843 sleep_on_head(q
, &wait
, &flags
);
3845 sleep_on_tail(q
, &wait
, &flags
);
3847 EXPORT_SYMBOL(interruptible_sleep_on
);
3850 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3852 unsigned long flags
;
3855 init_waitqueue_entry(&wait
, current
);
3857 current
->state
= TASK_INTERRUPTIBLE
;
3859 sleep_on_head(q
, &wait
, &flags
);
3860 timeout
= schedule_timeout(timeout
);
3861 sleep_on_tail(q
, &wait
, &flags
);
3865 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3867 void __sched
sleep_on(wait_queue_head_t
*q
)
3869 unsigned long flags
;
3872 init_waitqueue_entry(&wait
, current
);
3874 current
->state
= TASK_UNINTERRUPTIBLE
;
3876 sleep_on_head(q
, &wait
, &flags
);
3878 sleep_on_tail(q
, &wait
, &flags
);
3880 EXPORT_SYMBOL(sleep_on
);
3882 long __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3884 unsigned long flags
;
3887 init_waitqueue_entry(&wait
, current
);
3889 current
->state
= TASK_UNINTERRUPTIBLE
;
3891 sleep_on_head(q
, &wait
, &flags
);
3892 timeout
= schedule_timeout(timeout
);
3893 sleep_on_tail(q
, &wait
, &flags
);
3897 EXPORT_SYMBOL(sleep_on_timeout
);
3899 #ifdef CONFIG_RT_MUTEXES
3902 * rt_mutex_setprio - set the current priority of a task
3904 * @prio: prio value (kernel-internal form)
3906 * This function changes the 'effective' priority of a task. It does
3907 * not touch ->normal_prio like __setscheduler().
3909 * Used by the rt_mutex code to implement priority inheritance logic.
3911 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3913 unsigned long flags
;
3917 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3919 rq
= task_rq_lock(p
, &flags
);
3920 update_rq_clock(rq
);
3923 on_rq
= p
->se
.on_rq
;
3925 dequeue_task(rq
, p
, 0);
3928 p
->sched_class
= &rt_sched_class
;
3930 p
->sched_class
= &fair_sched_class
;
3935 enqueue_task(rq
, p
, 0);
3937 * Reschedule if we are currently running on this runqueue and
3938 * our priority decreased, or if we are not currently running on
3939 * this runqueue and our priority is higher than the current's
3941 if (task_running(rq
, p
)) {
3942 if (p
->prio
> oldprio
)
3943 resched_task(rq
->curr
);
3945 check_preempt_curr(rq
, p
);
3948 task_rq_unlock(rq
, &flags
);
3953 void set_user_nice(struct task_struct
*p
, long nice
)
3955 int old_prio
, delta
, on_rq
;
3956 unsigned long flags
;
3959 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3962 * We have to be careful, if called from sys_setpriority(),
3963 * the task might be in the middle of scheduling on another CPU.
3965 rq
= task_rq_lock(p
, &flags
);
3966 update_rq_clock(rq
);
3968 * The RT priorities are set via sched_setscheduler(), but we still
3969 * allow the 'normal' nice value to be set - but as expected
3970 * it wont have any effect on scheduling until the task is
3971 * SCHED_FIFO/SCHED_RR:
3973 if (task_has_rt_policy(p
)) {
3974 p
->static_prio
= NICE_TO_PRIO(nice
);
3977 on_rq
= p
->se
.on_rq
;
3979 dequeue_task(rq
, p
, 0);
3983 p
->static_prio
= NICE_TO_PRIO(nice
);
3986 p
->prio
= effective_prio(p
);
3987 delta
= p
->prio
- old_prio
;
3990 enqueue_task(rq
, p
, 0);
3993 * If the task increased its priority or is running and
3994 * lowered its priority, then reschedule its CPU:
3996 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3997 resched_task(rq
->curr
);
4000 task_rq_unlock(rq
, &flags
);
4002 EXPORT_SYMBOL(set_user_nice
);
4005 * can_nice - check if a task can reduce its nice value
4009 int can_nice(const struct task_struct
*p
, const int nice
)
4011 /* convert nice value [19,-20] to rlimit style value [1,40] */
4012 int nice_rlim
= 20 - nice
;
4014 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4015 capable(CAP_SYS_NICE
));
4018 #ifdef __ARCH_WANT_SYS_NICE
4021 * sys_nice - change the priority of the current process.
4022 * @increment: priority increment
4024 * sys_setpriority is a more generic, but much slower function that
4025 * does similar things.
4027 asmlinkage
long sys_nice(int increment
)
4032 * Setpriority might change our priority at the same moment.
4033 * We don't have to worry. Conceptually one call occurs first
4034 * and we have a single winner.
4036 if (increment
< -40)
4041 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4047 if (increment
< 0 && !can_nice(current
, nice
))
4050 retval
= security_task_setnice(current
, nice
);
4054 set_user_nice(current
, nice
);
4061 * task_prio - return the priority value of a given task.
4062 * @p: the task in question.
4064 * This is the priority value as seen by users in /proc.
4065 * RT tasks are offset by -200. Normal tasks are centered
4066 * around 0, value goes from -16 to +15.
4068 int task_prio(const struct task_struct
*p
)
4070 return p
->prio
- MAX_RT_PRIO
;
4074 * task_nice - return the nice value of a given task.
4075 * @p: the task in question.
4077 int task_nice(const struct task_struct
*p
)
4079 return TASK_NICE(p
);
4081 EXPORT_SYMBOL_GPL(task_nice
);
4084 * idle_cpu - is a given cpu idle currently?
4085 * @cpu: the processor in question.
4087 int idle_cpu(int cpu
)
4089 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4093 * idle_task - return the idle task for a given cpu.
4094 * @cpu: the processor in question.
4096 struct task_struct
*idle_task(int cpu
)
4098 return cpu_rq(cpu
)->idle
;
4102 * find_process_by_pid - find a process with a matching PID value.
4103 * @pid: the pid in question.
4105 static inline struct task_struct
*find_process_by_pid(pid_t pid
)
4107 return pid
? find_task_by_pid(pid
) : current
;
4110 /* Actually do priority change: must hold rq lock. */
4112 __setscheduler(struct rq
*rq
, struct task_struct
*p
, int policy
, int prio
)
4114 BUG_ON(p
->se
.on_rq
);
4117 switch (p
->policy
) {
4121 p
->sched_class
= &fair_sched_class
;
4125 p
->sched_class
= &rt_sched_class
;
4129 p
->rt_priority
= prio
;
4130 p
->normal_prio
= normal_prio(p
);
4131 /* we are holding p->pi_lock already */
4132 p
->prio
= rt_mutex_getprio(p
);
4137 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4138 * @p: the task in question.
4139 * @policy: new policy.
4140 * @param: structure containing the new RT priority.
4142 * NOTE that the task may be already dead.
4144 int sched_setscheduler(struct task_struct
*p
, int policy
,
4145 struct sched_param
*param
)
4147 int retval
, oldprio
, oldpolicy
= -1, on_rq
;
4148 unsigned long flags
;
4151 /* may grab non-irq protected spin_locks */
4152 BUG_ON(in_interrupt());
4154 /* double check policy once rq lock held */
4156 policy
= oldpolicy
= p
->policy
;
4157 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4158 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
&&
4159 policy
!= SCHED_IDLE
)
4162 * Valid priorities for SCHED_FIFO and SCHED_RR are
4163 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4164 * SCHED_BATCH and SCHED_IDLE is 0.
4166 if (param
->sched_priority
< 0 ||
4167 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4168 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4170 if (rt_policy(policy
) != (param
->sched_priority
!= 0))
4174 * Allow unprivileged RT tasks to decrease priority:
4176 if (!capable(CAP_SYS_NICE
)) {
4177 if (rt_policy(policy
)) {
4178 unsigned long rlim_rtprio
;
4180 if (!lock_task_sighand(p
, &flags
))
4182 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4183 unlock_task_sighand(p
, &flags
);
4185 /* can't set/change the rt policy */
4186 if (policy
!= p
->policy
&& !rlim_rtprio
)
4189 /* can't increase priority */
4190 if (param
->sched_priority
> p
->rt_priority
&&
4191 param
->sched_priority
> rlim_rtprio
)
4195 * Like positive nice levels, dont allow tasks to
4196 * move out of SCHED_IDLE either:
4198 if (p
->policy
== SCHED_IDLE
&& policy
!= SCHED_IDLE
)
4201 /* can't change other user's priorities */
4202 if ((current
->euid
!= p
->euid
) &&
4203 (current
->euid
!= p
->uid
))
4207 retval
= security_task_setscheduler(p
, policy
, param
);
4211 * make sure no PI-waiters arrive (or leave) while we are
4212 * changing the priority of the task:
4214 spin_lock_irqsave(&p
->pi_lock
, flags
);
4216 * To be able to change p->policy safely, the apropriate
4217 * runqueue lock must be held.
4219 rq
= __task_rq_lock(p
);
4220 /* recheck policy now with rq lock held */
4221 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4222 policy
= oldpolicy
= -1;
4223 __task_rq_unlock(rq
);
4224 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4227 update_rq_clock(rq
);
4228 on_rq
= p
->se
.on_rq
;
4230 deactivate_task(rq
, p
, 0);
4232 __setscheduler(rq
, p
, policy
, param
->sched_priority
);
4234 activate_task(rq
, p
, 0);
4236 * Reschedule if we are currently running on this runqueue and
4237 * our priority decreased, or if we are not currently running on
4238 * this runqueue and our priority is higher than the current's
4240 if (task_running(rq
, p
)) {
4241 if (p
->prio
> oldprio
)
4242 resched_task(rq
->curr
);
4244 check_preempt_curr(rq
, p
);
4247 __task_rq_unlock(rq
);
4248 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4250 rt_mutex_adjust_pi(p
);
4254 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4257 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4259 struct sched_param lparam
;
4260 struct task_struct
*p
;
4263 if (!param
|| pid
< 0)
4265 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4270 p
= find_process_by_pid(pid
);
4272 retval
= sched_setscheduler(p
, policy
, &lparam
);
4279 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4280 * @pid: the pid in question.
4281 * @policy: new policy.
4282 * @param: structure containing the new RT priority.
4284 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
4285 struct sched_param __user
*param
)
4287 /* negative values for policy are not valid */
4291 return do_sched_setscheduler(pid
, policy
, param
);
4295 * sys_sched_setparam - set/change the RT priority of a thread
4296 * @pid: the pid in question.
4297 * @param: structure containing the new RT priority.
4299 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4301 return do_sched_setscheduler(pid
, -1, param
);
4305 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4306 * @pid: the pid in question.
4308 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4310 struct task_struct
*p
;
4311 int retval
= -EINVAL
;
4317 read_lock(&tasklist_lock
);
4318 p
= find_process_by_pid(pid
);
4320 retval
= security_task_getscheduler(p
);
4324 read_unlock(&tasklist_lock
);
4331 * sys_sched_getscheduler - get the RT priority of a thread
4332 * @pid: the pid in question.
4333 * @param: structure containing the RT priority.
4335 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4337 struct sched_param lp
;
4338 struct task_struct
*p
;
4339 int retval
= -EINVAL
;
4341 if (!param
|| pid
< 0)
4344 read_lock(&tasklist_lock
);
4345 p
= find_process_by_pid(pid
);
4350 retval
= security_task_getscheduler(p
);
4354 lp
.sched_priority
= p
->rt_priority
;
4355 read_unlock(&tasklist_lock
);
4358 * This one might sleep, we cannot do it with a spinlock held ...
4360 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4366 read_unlock(&tasklist_lock
);
4370 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4372 cpumask_t cpus_allowed
;
4373 struct task_struct
*p
;
4376 mutex_lock(&sched_hotcpu_mutex
);
4377 read_lock(&tasklist_lock
);
4379 p
= find_process_by_pid(pid
);
4381 read_unlock(&tasklist_lock
);
4382 mutex_unlock(&sched_hotcpu_mutex
);
4387 * It is not safe to call set_cpus_allowed with the
4388 * tasklist_lock held. We will bump the task_struct's
4389 * usage count and then drop tasklist_lock.
4392 read_unlock(&tasklist_lock
);
4395 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4396 !capable(CAP_SYS_NICE
))
4399 retval
= security_task_setscheduler(p
, 0, NULL
);
4403 cpus_allowed
= cpuset_cpus_allowed(p
);
4404 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4405 retval
= set_cpus_allowed(p
, new_mask
);
4409 mutex_unlock(&sched_hotcpu_mutex
);
4413 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4414 cpumask_t
*new_mask
)
4416 if (len
< sizeof(cpumask_t
)) {
4417 memset(new_mask
, 0, sizeof(cpumask_t
));
4418 } else if (len
> sizeof(cpumask_t
)) {
4419 len
= sizeof(cpumask_t
);
4421 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4425 * sys_sched_setaffinity - set the cpu affinity of a process
4426 * @pid: pid of the process
4427 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4428 * @user_mask_ptr: user-space pointer to the new cpu mask
4430 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4431 unsigned long __user
*user_mask_ptr
)
4436 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4440 return sched_setaffinity(pid
, new_mask
);
4444 * Represents all cpu's present in the system
4445 * In systems capable of hotplug, this map could dynamically grow
4446 * as new cpu's are detected in the system via any platform specific
4447 * method, such as ACPI for e.g.
4450 cpumask_t cpu_present_map __read_mostly
;
4451 EXPORT_SYMBOL(cpu_present_map
);
4454 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4455 EXPORT_SYMBOL(cpu_online_map
);
4457 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4458 EXPORT_SYMBOL(cpu_possible_map
);
4461 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4463 struct task_struct
*p
;
4466 mutex_lock(&sched_hotcpu_mutex
);
4467 read_lock(&tasklist_lock
);
4470 p
= find_process_by_pid(pid
);
4474 retval
= security_task_getscheduler(p
);
4478 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4481 read_unlock(&tasklist_lock
);
4482 mutex_unlock(&sched_hotcpu_mutex
);
4488 * sys_sched_getaffinity - get the cpu affinity of a process
4489 * @pid: pid of the process
4490 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4491 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4493 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4494 unsigned long __user
*user_mask_ptr
)
4499 if (len
< sizeof(cpumask_t
))
4502 ret
= sched_getaffinity(pid
, &mask
);
4506 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4509 return sizeof(cpumask_t
);
4513 * sys_sched_yield - yield the current processor to other threads.
4515 * This function yields the current CPU to other tasks. If there are no
4516 * other threads running on this CPU then this function will return.
4518 asmlinkage
long sys_sched_yield(void)
4520 struct rq
*rq
= this_rq_lock();
4522 schedstat_inc(rq
, yld_cnt
);
4523 current
->sched_class
->yield_task(rq
, current
);
4526 * Since we are going to call schedule() anyway, there's
4527 * no need to preempt or enable interrupts:
4529 __release(rq
->lock
);
4530 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4531 _raw_spin_unlock(&rq
->lock
);
4532 preempt_enable_no_resched();
4539 static void __cond_resched(void)
4541 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4542 __might_sleep(__FILE__
, __LINE__
);
4545 * The BKS might be reacquired before we have dropped
4546 * PREEMPT_ACTIVE, which could trigger a second
4547 * cond_resched() call.
4550 add_preempt_count(PREEMPT_ACTIVE
);
4552 sub_preempt_count(PREEMPT_ACTIVE
);
4553 } while (need_resched());
4556 int __sched
cond_resched(void)
4558 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4559 system_state
== SYSTEM_RUNNING
) {
4565 EXPORT_SYMBOL(cond_resched
);
4568 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4569 * call schedule, and on return reacquire the lock.
4571 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4572 * operations here to prevent schedule() from being called twice (once via
4573 * spin_unlock(), once by hand).
4575 int cond_resched_lock(spinlock_t
*lock
)
4579 if (need_lockbreak(lock
)) {
4585 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4586 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4587 _raw_spin_unlock(lock
);
4588 preempt_enable_no_resched();
4595 EXPORT_SYMBOL(cond_resched_lock
);
4597 int __sched
cond_resched_softirq(void)
4599 BUG_ON(!in_softirq());
4601 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4609 EXPORT_SYMBOL(cond_resched_softirq
);
4612 * yield - yield the current processor to other threads.
4614 * This is a shortcut for kernel-space yielding - it marks the
4615 * thread runnable and calls sys_sched_yield().
4617 void __sched
yield(void)
4619 set_current_state(TASK_RUNNING
);
4622 EXPORT_SYMBOL(yield
);
4625 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4626 * that process accounting knows that this is a task in IO wait state.
4628 * But don't do that if it is a deliberate, throttling IO wait (this task
4629 * has set its backing_dev_info: the queue against which it should throttle)
4631 void __sched
io_schedule(void)
4633 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4635 delayacct_blkio_start();
4636 atomic_inc(&rq
->nr_iowait
);
4638 atomic_dec(&rq
->nr_iowait
);
4639 delayacct_blkio_end();
4641 EXPORT_SYMBOL(io_schedule
);
4643 long __sched
io_schedule_timeout(long timeout
)
4645 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4648 delayacct_blkio_start();
4649 atomic_inc(&rq
->nr_iowait
);
4650 ret
= schedule_timeout(timeout
);
4651 atomic_dec(&rq
->nr_iowait
);
4652 delayacct_blkio_end();
4657 * sys_sched_get_priority_max - return maximum RT priority.
4658 * @policy: scheduling class.
4660 * this syscall returns the maximum rt_priority that can be used
4661 * by a given scheduling class.
4663 asmlinkage
long sys_sched_get_priority_max(int policy
)
4670 ret
= MAX_USER_RT_PRIO
-1;
4682 * sys_sched_get_priority_min - return minimum RT priority.
4683 * @policy: scheduling class.
4685 * this syscall returns the minimum rt_priority that can be used
4686 * by a given scheduling class.
4688 asmlinkage
long sys_sched_get_priority_min(int policy
)
4706 * sys_sched_rr_get_interval - return the default timeslice of a process.
4707 * @pid: pid of the process.
4708 * @interval: userspace pointer to the timeslice value.
4710 * this syscall writes the default timeslice value of a given process
4711 * into the user-space timespec buffer. A value of '0' means infinity.
4714 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4716 struct task_struct
*p
;
4717 int retval
= -EINVAL
;
4724 read_lock(&tasklist_lock
);
4725 p
= find_process_by_pid(pid
);
4729 retval
= security_task_getscheduler(p
);
4733 jiffies_to_timespec(p
->policy
== SCHED_FIFO
?
4734 0 : static_prio_timeslice(p
->static_prio
), &t
);
4735 read_unlock(&tasklist_lock
);
4736 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4740 read_unlock(&tasklist_lock
);
4744 static const char stat_nam
[] = "RSDTtZX";
4746 static void show_task(struct task_struct
*p
)
4748 unsigned long free
= 0;
4751 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4752 printk("%-13.13s %c", p
->comm
,
4753 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4754 #if BITS_PER_LONG == 32
4755 if (state
== TASK_RUNNING
)
4756 printk(" running ");
4758 printk(" %08lx ", thread_saved_pc(p
));
4760 if (state
== TASK_RUNNING
)
4761 printk(" running task ");
4763 printk(" %016lx ", thread_saved_pc(p
));
4765 #ifdef CONFIG_DEBUG_STACK_USAGE
4767 unsigned long *n
= end_of_stack(p
);
4770 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4773 printk("%5lu %5d %6d\n", free
, p
->pid
, p
->parent
->pid
);
4775 if (state
!= TASK_RUNNING
)
4776 show_stack(p
, NULL
);
4779 void show_state_filter(unsigned long state_filter
)
4781 struct task_struct
*g
, *p
;
4783 #if BITS_PER_LONG == 32
4785 " task PC stack pid father\n");
4788 " task PC stack pid father\n");
4790 read_lock(&tasklist_lock
);
4791 do_each_thread(g
, p
) {
4793 * reset the NMI-timeout, listing all files on a slow
4794 * console might take alot of time:
4796 touch_nmi_watchdog();
4797 if (!state_filter
|| (p
->state
& state_filter
))
4799 } while_each_thread(g
, p
);
4801 touch_all_softlockup_watchdogs();
4803 #ifdef CONFIG_SCHED_DEBUG
4804 sysrq_sched_debug_show();
4806 read_unlock(&tasklist_lock
);
4808 * Only show locks if all tasks are dumped:
4810 if (state_filter
== -1)
4811 debug_show_all_locks();
4814 void __cpuinit
init_idle_bootup_task(struct task_struct
*idle
)
4816 idle
->sched_class
= &idle_sched_class
;
4820 * init_idle - set up an idle thread for a given CPU
4821 * @idle: task in question
4822 * @cpu: cpu the idle task belongs to
4824 * NOTE: this function does not set the idle thread's NEED_RESCHED
4825 * flag, to make booting more robust.
4827 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4829 struct rq
*rq
= cpu_rq(cpu
);
4830 unsigned long flags
;
4833 idle
->se
.exec_start
= sched_clock();
4835 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4836 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4837 __set_task_cpu(idle
, cpu
);
4839 spin_lock_irqsave(&rq
->lock
, flags
);
4840 rq
->curr
= rq
->idle
= idle
;
4841 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4844 spin_unlock_irqrestore(&rq
->lock
, flags
);
4846 /* Set the preempt count _outside_ the spinlocks! */
4847 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4848 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4850 task_thread_info(idle
)->preempt_count
= 0;
4853 * The idle tasks have their own, simple scheduling class:
4855 idle
->sched_class
= &idle_sched_class
;
4859 * In a system that switches off the HZ timer nohz_cpu_mask
4860 * indicates which cpus entered this state. This is used
4861 * in the rcu update to wait only for active cpus. For system
4862 * which do not switch off the HZ timer nohz_cpu_mask should
4863 * always be CPU_MASK_NONE.
4865 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4869 * This is how migration works:
4871 * 1) we queue a struct migration_req structure in the source CPU's
4872 * runqueue and wake up that CPU's migration thread.
4873 * 2) we down() the locked semaphore => thread blocks.
4874 * 3) migration thread wakes up (implicitly it forces the migrated
4875 * thread off the CPU)
4876 * 4) it gets the migration request and checks whether the migrated
4877 * task is still in the wrong runqueue.
4878 * 5) if it's in the wrong runqueue then the migration thread removes
4879 * it and puts it into the right queue.
4880 * 6) migration thread up()s the semaphore.
4881 * 7) we wake up and the migration is done.
4885 * Change a given task's CPU affinity. Migrate the thread to a
4886 * proper CPU and schedule it away if the CPU it's executing on
4887 * is removed from the allowed bitmask.
4889 * NOTE: the caller must have a valid reference to the task, the
4890 * task must not exit() & deallocate itself prematurely. The
4891 * call is not atomic; no spinlocks may be held.
4893 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
4895 struct migration_req req
;
4896 unsigned long flags
;
4900 rq
= task_rq_lock(p
, &flags
);
4901 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4906 p
->cpus_allowed
= new_mask
;
4907 /* Can the task run on the task's current CPU? If so, we're done */
4908 if (cpu_isset(task_cpu(p
), new_mask
))
4911 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4912 /* Need help from migration thread: drop lock and wait. */
4913 task_rq_unlock(rq
, &flags
);
4914 wake_up_process(rq
->migration_thread
);
4915 wait_for_completion(&req
.done
);
4916 tlb_migrate_finish(p
->mm
);
4920 task_rq_unlock(rq
, &flags
);
4924 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4927 * Move (not current) task off this cpu, onto dest cpu. We're doing
4928 * this because either it can't run here any more (set_cpus_allowed()
4929 * away from this CPU, or CPU going down), or because we're
4930 * attempting to rebalance this task on exec (sched_exec).
4932 * So we race with normal scheduler movements, but that's OK, as long
4933 * as the task is no longer on this CPU.
4935 * Returns non-zero if task was successfully migrated.
4937 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4939 struct rq
*rq_dest
, *rq_src
;
4942 if (unlikely(cpu_is_offline(dest_cpu
)))
4945 rq_src
= cpu_rq(src_cpu
);
4946 rq_dest
= cpu_rq(dest_cpu
);
4948 double_rq_lock(rq_src
, rq_dest
);
4949 /* Already moved. */
4950 if (task_cpu(p
) != src_cpu
)
4952 /* Affinity changed (again). */
4953 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4956 on_rq
= p
->se
.on_rq
;
4958 deactivate_task(rq_src
, p
, 0);
4960 set_task_cpu(p
, dest_cpu
);
4962 activate_task(rq_dest
, p
, 0);
4963 check_preempt_curr(rq_dest
, p
);
4967 double_rq_unlock(rq_src
, rq_dest
);
4972 * migration_thread - this is a highprio system thread that performs
4973 * thread migration by bumping thread off CPU then 'pushing' onto
4976 static int migration_thread(void *data
)
4978 int cpu
= (long)data
;
4982 BUG_ON(rq
->migration_thread
!= current
);
4984 set_current_state(TASK_INTERRUPTIBLE
);
4985 while (!kthread_should_stop()) {
4986 struct migration_req
*req
;
4987 struct list_head
*head
;
4989 spin_lock_irq(&rq
->lock
);
4991 if (cpu_is_offline(cpu
)) {
4992 spin_unlock_irq(&rq
->lock
);
4996 if (rq
->active_balance
) {
4997 active_load_balance(rq
, cpu
);
4998 rq
->active_balance
= 0;
5001 head
= &rq
->migration_queue
;
5003 if (list_empty(head
)) {
5004 spin_unlock_irq(&rq
->lock
);
5006 set_current_state(TASK_INTERRUPTIBLE
);
5009 req
= list_entry(head
->next
, struct migration_req
, list
);
5010 list_del_init(head
->next
);
5012 spin_unlock(&rq
->lock
);
5013 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5016 complete(&req
->done
);
5018 __set_current_state(TASK_RUNNING
);
5022 /* Wait for kthread_stop */
5023 set_current_state(TASK_INTERRUPTIBLE
);
5024 while (!kthread_should_stop()) {
5026 set_current_state(TASK_INTERRUPTIBLE
);
5028 __set_current_state(TASK_RUNNING
);
5032 #ifdef CONFIG_HOTPLUG_CPU
5034 * Figure out where task on dead CPU should go, use force if neccessary.
5035 * NOTE: interrupts should be disabled by the caller
5037 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5039 unsigned long flags
;
5046 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5047 cpus_and(mask
, mask
, p
->cpus_allowed
);
5048 dest_cpu
= any_online_cpu(mask
);
5050 /* On any allowed CPU? */
5051 if (dest_cpu
== NR_CPUS
)
5052 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5054 /* No more Mr. Nice Guy. */
5055 if (dest_cpu
== NR_CPUS
) {
5056 rq
= task_rq_lock(p
, &flags
);
5057 cpus_setall(p
->cpus_allowed
);
5058 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5059 task_rq_unlock(rq
, &flags
);
5062 * Don't tell them about moving exiting tasks or
5063 * kernel threads (both mm NULL), since they never
5066 if (p
->mm
&& printk_ratelimit())
5067 printk(KERN_INFO
"process %d (%s) no "
5068 "longer affine to cpu%d\n",
5069 p
->pid
, p
->comm
, dead_cpu
);
5071 if (!__migrate_task(p
, dead_cpu
, dest_cpu
))
5076 * While a dead CPU has no uninterruptible tasks queued at this point,
5077 * it might still have a nonzero ->nr_uninterruptible counter, because
5078 * for performance reasons the counter is not stricly tracking tasks to
5079 * their home CPUs. So we just add the counter to another CPU's counter,
5080 * to keep the global sum constant after CPU-down:
5082 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5084 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5085 unsigned long flags
;
5087 local_irq_save(flags
);
5088 double_rq_lock(rq_src
, rq_dest
);
5089 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5090 rq_src
->nr_uninterruptible
= 0;
5091 double_rq_unlock(rq_src
, rq_dest
);
5092 local_irq_restore(flags
);
5095 /* Run through task list and migrate tasks from the dead cpu. */
5096 static void migrate_live_tasks(int src_cpu
)
5098 struct task_struct
*p
, *t
;
5100 write_lock_irq(&tasklist_lock
);
5102 do_each_thread(t
, p
) {
5106 if (task_cpu(p
) == src_cpu
)
5107 move_task_off_dead_cpu(src_cpu
, p
);
5108 } while_each_thread(t
, p
);
5110 write_unlock_irq(&tasklist_lock
);
5114 * Schedules idle task to be the next runnable task on current CPU.
5115 * It does so by boosting its priority to highest possible and adding it to
5116 * the _front_ of the runqueue. Used by CPU offline code.
5118 void sched_idle_next(void)
5120 int this_cpu
= smp_processor_id();
5121 struct rq
*rq
= cpu_rq(this_cpu
);
5122 struct task_struct
*p
= rq
->idle
;
5123 unsigned long flags
;
5125 /* cpu has to be offline */
5126 BUG_ON(cpu_online(this_cpu
));
5129 * Strictly not necessary since rest of the CPUs are stopped by now
5130 * and interrupts disabled on the current cpu.
5132 spin_lock_irqsave(&rq
->lock
, flags
);
5134 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5136 /* Add idle task to the _front_ of its priority queue: */
5137 activate_idle_task(p
, rq
);
5139 spin_unlock_irqrestore(&rq
->lock
, flags
);
5143 * Ensures that the idle task is using init_mm right before its cpu goes
5146 void idle_task_exit(void)
5148 struct mm_struct
*mm
= current
->active_mm
;
5150 BUG_ON(cpu_online(smp_processor_id()));
5153 switch_mm(mm
, &init_mm
, current
);
5157 /* called under rq->lock with disabled interrupts */
5158 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5160 struct rq
*rq
= cpu_rq(dead_cpu
);
5162 /* Must be exiting, otherwise would be on tasklist. */
5163 BUG_ON(p
->exit_state
!= EXIT_ZOMBIE
&& p
->exit_state
!= EXIT_DEAD
);
5165 /* Cannot have done final schedule yet: would have vanished. */
5166 BUG_ON(p
->state
== TASK_DEAD
);
5171 * Drop lock around migration; if someone else moves it,
5172 * that's OK. No task can be added to this CPU, so iteration is
5174 * NOTE: interrupts should be left disabled --dev@
5176 spin_unlock(&rq
->lock
);
5177 move_task_off_dead_cpu(dead_cpu
, p
);
5178 spin_lock(&rq
->lock
);
5183 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5184 static void migrate_dead_tasks(unsigned int dead_cpu
)
5186 struct rq
*rq
= cpu_rq(dead_cpu
);
5187 struct task_struct
*next
;
5190 if (!rq
->nr_running
)
5192 update_rq_clock(rq
);
5193 next
= pick_next_task(rq
, rq
->curr
);
5196 migrate_dead(dead_cpu
, next
);
5200 #endif /* CONFIG_HOTPLUG_CPU */
5202 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5204 static struct ctl_table sd_ctl_dir
[] = {
5206 .procname
= "sched_domain",
5212 static struct ctl_table sd_ctl_root
[] = {
5214 .ctl_name
= CTL_KERN
,
5215 .procname
= "kernel",
5217 .child
= sd_ctl_dir
,
5222 static struct ctl_table
*sd_alloc_ctl_entry(int n
)
5224 struct ctl_table
*entry
=
5225 kmalloc(n
* sizeof(struct ctl_table
), GFP_KERNEL
);
5228 memset(entry
, 0, n
* sizeof(struct ctl_table
));
5234 set_table_entry(struct ctl_table
*entry
,
5235 const char *procname
, void *data
, int maxlen
,
5236 mode_t mode
, proc_handler
*proc_handler
)
5238 entry
->procname
= procname
;
5240 entry
->maxlen
= maxlen
;
5242 entry
->proc_handler
= proc_handler
;
5245 static struct ctl_table
*
5246 sd_alloc_ctl_domain_table(struct sched_domain
*sd
)
5248 struct ctl_table
*table
= sd_alloc_ctl_entry(14);
5250 set_table_entry(&table
[0], "min_interval", &sd
->min_interval
,
5251 sizeof(long), 0644, proc_doulongvec_minmax
);
5252 set_table_entry(&table
[1], "max_interval", &sd
->max_interval
,
5253 sizeof(long), 0644, proc_doulongvec_minmax
);
5254 set_table_entry(&table
[2], "busy_idx", &sd
->busy_idx
,
5255 sizeof(int), 0644, proc_dointvec_minmax
);
5256 set_table_entry(&table
[3], "idle_idx", &sd
->idle_idx
,
5257 sizeof(int), 0644, proc_dointvec_minmax
);
5258 set_table_entry(&table
[4], "newidle_idx", &sd
->newidle_idx
,
5259 sizeof(int), 0644, proc_dointvec_minmax
);
5260 set_table_entry(&table
[5], "wake_idx", &sd
->wake_idx
,
5261 sizeof(int), 0644, proc_dointvec_minmax
);
5262 set_table_entry(&table
[6], "forkexec_idx", &sd
->forkexec_idx
,
5263 sizeof(int), 0644, proc_dointvec_minmax
);
5264 set_table_entry(&table
[7], "busy_factor", &sd
->busy_factor
,
5265 sizeof(int), 0644, proc_dointvec_minmax
);
5266 set_table_entry(&table
[8], "imbalance_pct", &sd
->imbalance_pct
,
5267 sizeof(int), 0644, proc_dointvec_minmax
);
5268 set_table_entry(&table
[10], "cache_nice_tries",
5269 &sd
->cache_nice_tries
,
5270 sizeof(int), 0644, proc_dointvec_minmax
);
5271 set_table_entry(&table
[12], "flags", &sd
->flags
,
5272 sizeof(int), 0644, proc_dointvec_minmax
);
5277 static ctl_table
*sd_alloc_ctl_cpu_table(int cpu
)
5279 struct ctl_table
*entry
, *table
;
5280 struct sched_domain
*sd
;
5281 int domain_num
= 0, i
;
5284 for_each_domain(cpu
, sd
)
5286 entry
= table
= sd_alloc_ctl_entry(domain_num
+ 1);
5289 for_each_domain(cpu
, sd
) {
5290 snprintf(buf
, 32, "domain%d", i
);
5291 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5293 entry
->child
= sd_alloc_ctl_domain_table(sd
);
5300 static struct ctl_table_header
*sd_sysctl_header
;
5301 static void init_sched_domain_sysctl(void)
5303 int i
, cpu_num
= num_online_cpus();
5304 struct ctl_table
*entry
= sd_alloc_ctl_entry(cpu_num
+ 1);
5307 sd_ctl_dir
[0].child
= entry
;
5309 for (i
= 0; i
< cpu_num
; i
++, entry
++) {
5310 snprintf(buf
, 32, "cpu%d", i
);
5311 entry
->procname
= kstrdup(buf
, GFP_KERNEL
);
5313 entry
->child
= sd_alloc_ctl_cpu_table(i
);
5315 sd_sysctl_header
= register_sysctl_table(sd_ctl_root
);
5318 static void init_sched_domain_sysctl(void)
5324 * migration_call - callback that gets triggered when a CPU is added.
5325 * Here we can start up the necessary migration thread for the new CPU.
5327 static int __cpuinit
5328 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5330 struct task_struct
*p
;
5331 int cpu
= (long)hcpu
;
5332 unsigned long flags
;
5336 case CPU_LOCK_ACQUIRE
:
5337 mutex_lock(&sched_hotcpu_mutex
);
5340 case CPU_UP_PREPARE
:
5341 case CPU_UP_PREPARE_FROZEN
:
5342 p
= kthread_create(migration_thread
, hcpu
, "migration/%d", cpu
);
5345 kthread_bind(p
, cpu
);
5346 /* Must be high prio: stop_machine expects to yield to it. */
5347 rq
= task_rq_lock(p
, &flags
);
5348 __setscheduler(rq
, p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5349 task_rq_unlock(rq
, &flags
);
5350 cpu_rq(cpu
)->migration_thread
= p
;
5354 case CPU_ONLINE_FROZEN
:
5355 /* Strictly unneccessary, as first user will wake it. */
5356 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5359 #ifdef CONFIG_HOTPLUG_CPU
5360 case CPU_UP_CANCELED
:
5361 case CPU_UP_CANCELED_FROZEN
:
5362 if (!cpu_rq(cpu
)->migration_thread
)
5364 /* Unbind it from offline cpu so it can run. Fall thru. */
5365 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5366 any_online_cpu(cpu_online_map
));
5367 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5368 cpu_rq(cpu
)->migration_thread
= NULL
;
5372 case CPU_DEAD_FROZEN
:
5373 migrate_live_tasks(cpu
);
5375 kthread_stop(rq
->migration_thread
);
5376 rq
->migration_thread
= NULL
;
5377 /* Idle task back to normal (off runqueue, low prio) */
5378 rq
= task_rq_lock(rq
->idle
, &flags
);
5379 update_rq_clock(rq
);
5380 deactivate_task(rq
, rq
->idle
, 0);
5381 rq
->idle
->static_prio
= MAX_PRIO
;
5382 __setscheduler(rq
, rq
->idle
, SCHED_NORMAL
, 0);
5383 rq
->idle
->sched_class
= &idle_sched_class
;
5384 migrate_dead_tasks(cpu
);
5385 task_rq_unlock(rq
, &flags
);
5386 migrate_nr_uninterruptible(rq
);
5387 BUG_ON(rq
->nr_running
!= 0);
5389 /* No need to migrate the tasks: it was best-effort if
5390 * they didn't take sched_hotcpu_mutex. Just wake up
5391 * the requestors. */
5392 spin_lock_irq(&rq
->lock
);
5393 while (!list_empty(&rq
->migration_queue
)) {
5394 struct migration_req
*req
;
5396 req
= list_entry(rq
->migration_queue
.next
,
5397 struct migration_req
, list
);
5398 list_del_init(&req
->list
);
5399 complete(&req
->done
);
5401 spin_unlock_irq(&rq
->lock
);
5404 case CPU_LOCK_RELEASE
:
5405 mutex_unlock(&sched_hotcpu_mutex
);
5411 /* Register at highest priority so that task migration (migrate_all_tasks)
5412 * happens before everything else.
5414 static struct notifier_block __cpuinitdata migration_notifier
= {
5415 .notifier_call
= migration_call
,
5419 int __init
migration_init(void)
5421 void *cpu
= (void *)(long)smp_processor_id();
5424 /* Start one for the boot CPU: */
5425 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5426 BUG_ON(err
== NOTIFY_BAD
);
5427 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5428 register_cpu_notifier(&migration_notifier
);
5436 /* Number of possible processor ids */
5437 int nr_cpu_ids __read_mostly
= NR_CPUS
;
5438 EXPORT_SYMBOL(nr_cpu_ids
);
5440 #undef SCHED_DOMAIN_DEBUG
5441 #ifdef SCHED_DOMAIN_DEBUG
5442 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5447 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5451 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5456 struct sched_group
*group
= sd
->groups
;
5457 cpumask_t groupmask
;
5459 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5460 cpus_clear(groupmask
);
5463 for (i
= 0; i
< level
+ 1; i
++)
5465 printk("domain %d: ", level
);
5467 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5468 printk("does not load-balance\n");
5470 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5475 printk("span %s\n", str
);
5477 if (!cpu_isset(cpu
, sd
->span
))
5478 printk(KERN_ERR
"ERROR: domain->span does not contain "
5480 if (!cpu_isset(cpu
, group
->cpumask
))
5481 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5485 for (i
= 0; i
< level
+ 2; i
++)
5491 printk(KERN_ERR
"ERROR: group is NULL\n");
5495 if (!group
->__cpu_power
) {
5497 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5501 if (!cpus_weight(group
->cpumask
)) {
5503 printk(KERN_ERR
"ERROR: empty group\n");
5506 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5508 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5511 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5513 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5516 group
= group
->next
;
5517 } while (group
!= sd
->groups
);
5520 if (!cpus_equal(sd
->span
, groupmask
))
5521 printk(KERN_ERR
"ERROR: groups don't span "
5529 if (!cpus_subset(groupmask
, sd
->span
))
5530 printk(KERN_ERR
"ERROR: parent span is not a superset "
5531 "of domain->span\n");
5536 # define sched_domain_debug(sd, cpu) do { } while (0)
5539 static int sd_degenerate(struct sched_domain
*sd
)
5541 if (cpus_weight(sd
->span
) == 1)
5544 /* Following flags need at least 2 groups */
5545 if (sd
->flags
& (SD_LOAD_BALANCE
|
5546 SD_BALANCE_NEWIDLE
|
5550 SD_SHARE_PKG_RESOURCES
)) {
5551 if (sd
->groups
!= sd
->groups
->next
)
5555 /* Following flags don't use groups */
5556 if (sd
->flags
& (SD_WAKE_IDLE
|
5565 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5567 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5569 if (sd_degenerate(parent
))
5572 if (!cpus_equal(sd
->span
, parent
->span
))
5575 /* Does parent contain flags not in child? */
5576 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5577 if (cflags
& SD_WAKE_AFFINE
)
5578 pflags
&= ~SD_WAKE_BALANCE
;
5579 /* Flags needing groups don't count if only 1 group in parent */
5580 if (parent
->groups
== parent
->groups
->next
) {
5581 pflags
&= ~(SD_LOAD_BALANCE
|
5582 SD_BALANCE_NEWIDLE
|
5586 SD_SHARE_PKG_RESOURCES
);
5588 if (~cflags
& pflags
)
5595 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5596 * hold the hotplug lock.
5598 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5600 struct rq
*rq
= cpu_rq(cpu
);
5601 struct sched_domain
*tmp
;
5603 /* Remove the sched domains which do not contribute to scheduling. */
5604 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5605 struct sched_domain
*parent
= tmp
->parent
;
5608 if (sd_parent_degenerate(tmp
, parent
)) {
5609 tmp
->parent
= parent
->parent
;
5611 parent
->parent
->child
= tmp
;
5615 if (sd
&& sd_degenerate(sd
)) {
5621 sched_domain_debug(sd
, cpu
);
5623 rcu_assign_pointer(rq
->sd
, sd
);
5626 /* cpus with isolated domains */
5627 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5629 /* Setup the mask of cpus configured for isolated domains */
5630 static int __init
isolated_cpu_setup(char *str
)
5632 int ints
[NR_CPUS
], i
;
5634 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5635 cpus_clear(cpu_isolated_map
);
5636 for (i
= 1; i
<= ints
[0]; i
++)
5637 if (ints
[i
] < NR_CPUS
)
5638 cpu_set(ints
[i
], cpu_isolated_map
);
5642 __setup ("isolcpus=", isolated_cpu_setup
);
5645 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5646 * to a function which identifies what group(along with sched group) a CPU
5647 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5648 * (due to the fact that we keep track of groups covered with a cpumask_t).
5650 * init_sched_build_groups will build a circular linked list of the groups
5651 * covered by the given span, and will set each group's ->cpumask correctly,
5652 * and ->cpu_power to 0.
5655 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5656 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5657 struct sched_group
**sg
))
5659 struct sched_group
*first
= NULL
, *last
= NULL
;
5660 cpumask_t covered
= CPU_MASK_NONE
;
5663 for_each_cpu_mask(i
, span
) {
5664 struct sched_group
*sg
;
5665 int group
= group_fn(i
, cpu_map
, &sg
);
5668 if (cpu_isset(i
, covered
))
5671 sg
->cpumask
= CPU_MASK_NONE
;
5672 sg
->__cpu_power
= 0;
5674 for_each_cpu_mask(j
, span
) {
5675 if (group_fn(j
, cpu_map
, NULL
) != group
)
5678 cpu_set(j
, covered
);
5679 cpu_set(j
, sg
->cpumask
);
5690 #define SD_NODES_PER_DOMAIN 16
5695 * find_next_best_node - find the next node to include in a sched_domain
5696 * @node: node whose sched_domain we're building
5697 * @used_nodes: nodes already in the sched_domain
5699 * Find the next node to include in a given scheduling domain. Simply
5700 * finds the closest node not already in the @used_nodes map.
5702 * Should use nodemask_t.
5704 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5706 int i
, n
, val
, min_val
, best_node
= 0;
5710 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5711 /* Start at @node */
5712 n
= (node
+ i
) % MAX_NUMNODES
;
5714 if (!nr_cpus_node(n
))
5717 /* Skip already used nodes */
5718 if (test_bit(n
, used_nodes
))
5721 /* Simple min distance search */
5722 val
= node_distance(node
, n
);
5724 if (val
< min_val
) {
5730 set_bit(best_node
, used_nodes
);
5735 * sched_domain_node_span - get a cpumask for a node's sched_domain
5736 * @node: node whose cpumask we're constructing
5737 * @size: number of nodes to include in this span
5739 * Given a node, construct a good cpumask for its sched_domain to span. It
5740 * should be one that prevents unnecessary balancing, but also spreads tasks
5743 static cpumask_t
sched_domain_node_span(int node
)
5745 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5746 cpumask_t span
, nodemask
;
5750 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5752 nodemask
= node_to_cpumask(node
);
5753 cpus_or(span
, span
, nodemask
);
5754 set_bit(node
, used_nodes
);
5756 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5757 int next_node
= find_next_best_node(node
, used_nodes
);
5759 nodemask
= node_to_cpumask(next_node
);
5760 cpus_or(span
, span
, nodemask
);
5767 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
5770 * SMT sched-domains:
5772 #ifdef CONFIG_SCHED_SMT
5773 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5774 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
5776 static int cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
,
5777 struct sched_group
**sg
)
5780 *sg
= &per_cpu(sched_group_cpus
, cpu
);
5786 * multi-core sched-domains:
5788 #ifdef CONFIG_SCHED_MC
5789 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
5790 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
5793 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
5794 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
5795 struct sched_group
**sg
)
5798 cpumask_t mask
= cpu_sibling_map
[cpu
];
5799 cpus_and(mask
, mask
, *cpu_map
);
5800 group
= first_cpu(mask
);
5802 *sg
= &per_cpu(sched_group_core
, group
);
5805 #elif defined(CONFIG_SCHED_MC)
5806 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
5807 struct sched_group
**sg
)
5810 *sg
= &per_cpu(sched_group_core
, cpu
);
5815 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5816 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
5818 static int cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
,
5819 struct sched_group
**sg
)
5822 #ifdef CONFIG_SCHED_MC
5823 cpumask_t mask
= cpu_coregroup_map(cpu
);
5824 cpus_and(mask
, mask
, *cpu_map
);
5825 group
= first_cpu(mask
);
5826 #elif defined(CONFIG_SCHED_SMT)
5827 cpumask_t mask
= cpu_sibling_map
[cpu
];
5828 cpus_and(mask
, mask
, *cpu_map
);
5829 group
= first_cpu(mask
);
5834 *sg
= &per_cpu(sched_group_phys
, group
);
5840 * The init_sched_build_groups can't handle what we want to do with node
5841 * groups, so roll our own. Now each node has its own list of groups which
5842 * gets dynamically allocated.
5844 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5845 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5847 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5848 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
5850 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
5851 struct sched_group
**sg
)
5853 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
5856 cpus_and(nodemask
, nodemask
, *cpu_map
);
5857 group
= first_cpu(nodemask
);
5860 *sg
= &per_cpu(sched_group_allnodes
, group
);
5864 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
5866 struct sched_group
*sg
= group_head
;
5872 for_each_cpu_mask(j
, sg
->cpumask
) {
5873 struct sched_domain
*sd
;
5875 sd
= &per_cpu(phys_domains
, j
);
5876 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5878 * Only add "power" once for each
5884 sg_inc_cpu_power(sg
, sd
->groups
->__cpu_power
);
5887 if (sg
!= group_head
)
5893 /* Free memory allocated for various sched_group structures */
5894 static void free_sched_groups(const cpumask_t
*cpu_map
)
5898 for_each_cpu_mask(cpu
, *cpu_map
) {
5899 struct sched_group
**sched_group_nodes
5900 = sched_group_nodes_bycpu
[cpu
];
5902 if (!sched_group_nodes
)
5905 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5906 cpumask_t nodemask
= node_to_cpumask(i
);
5907 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5909 cpus_and(nodemask
, nodemask
, *cpu_map
);
5910 if (cpus_empty(nodemask
))
5920 if (oldsg
!= sched_group_nodes
[i
])
5923 kfree(sched_group_nodes
);
5924 sched_group_nodes_bycpu
[cpu
] = NULL
;
5928 static void free_sched_groups(const cpumask_t
*cpu_map
)
5934 * Initialize sched groups cpu_power.
5936 * cpu_power indicates the capacity of sched group, which is used while
5937 * distributing the load between different sched groups in a sched domain.
5938 * Typically cpu_power for all the groups in a sched domain will be same unless
5939 * there are asymmetries in the topology. If there are asymmetries, group
5940 * having more cpu_power will pickup more load compared to the group having
5943 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
5944 * the maximum number of tasks a group can handle in the presence of other idle
5945 * or lightly loaded groups in the same sched domain.
5947 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
5949 struct sched_domain
*child
;
5950 struct sched_group
*group
;
5952 WARN_ON(!sd
|| !sd
->groups
);
5954 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
5959 sd
->groups
->__cpu_power
= 0;
5962 * For perf policy, if the groups in child domain share resources
5963 * (for example cores sharing some portions of the cache hierarchy
5964 * or SMT), then set this domain groups cpu_power such that each group
5965 * can handle only one task, when there are other idle groups in the
5966 * same sched domain.
5968 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
5970 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
5971 sg_inc_cpu_power(sd
->groups
, SCHED_LOAD_SCALE
);
5976 * add cpu_power of each child group to this groups cpu_power
5978 group
= child
->groups
;
5980 sg_inc_cpu_power(sd
->groups
, group
->__cpu_power
);
5981 group
= group
->next
;
5982 } while (group
!= child
->groups
);
5986 * Build sched domains for a given set of cpus and attach the sched domains
5987 * to the individual cpus
5989 static int build_sched_domains(const cpumask_t
*cpu_map
)
5993 struct sched_group
**sched_group_nodes
= NULL
;
5994 int sd_allnodes
= 0;
5997 * Allocate the per-node list of sched groups
5999 sched_group_nodes
= kzalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
6001 if (!sched_group_nodes
) {
6002 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6005 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6009 * Set up domains for cpus specified by the cpu_map.
6011 for_each_cpu_mask(i
, *cpu_map
) {
6012 struct sched_domain
*sd
= NULL
, *p
;
6013 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6015 cpus_and(nodemask
, nodemask
, *cpu_map
);
6018 if (cpus_weight(*cpu_map
) >
6019 SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6020 sd
= &per_cpu(allnodes_domains
, i
);
6021 *sd
= SD_ALLNODES_INIT
;
6022 sd
->span
= *cpu_map
;
6023 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6029 sd
= &per_cpu(node_domains
, i
);
6031 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6035 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6039 sd
= &per_cpu(phys_domains
, i
);
6041 sd
->span
= nodemask
;
6045 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6047 #ifdef CONFIG_SCHED_MC
6049 sd
= &per_cpu(core_domains
, i
);
6051 sd
->span
= cpu_coregroup_map(i
);
6052 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6055 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6058 #ifdef CONFIG_SCHED_SMT
6060 sd
= &per_cpu(cpu_domains
, i
);
6061 *sd
= SD_SIBLING_INIT
;
6062 sd
->span
= cpu_sibling_map
[i
];
6063 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6066 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6070 #ifdef CONFIG_SCHED_SMT
6071 /* Set up CPU (sibling) groups */
6072 for_each_cpu_mask(i
, *cpu_map
) {
6073 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
6074 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6075 if (i
!= first_cpu(this_sibling_map
))
6078 init_sched_build_groups(this_sibling_map
, cpu_map
,
6083 #ifdef CONFIG_SCHED_MC
6084 /* Set up multi-core groups */
6085 for_each_cpu_mask(i
, *cpu_map
) {
6086 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6087 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6088 if (i
!= first_cpu(this_core_map
))
6090 init_sched_build_groups(this_core_map
, cpu_map
,
6091 &cpu_to_core_group
);
6095 /* Set up physical groups */
6096 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6097 cpumask_t nodemask
= node_to_cpumask(i
);
6099 cpus_and(nodemask
, nodemask
, *cpu_map
);
6100 if (cpus_empty(nodemask
))
6103 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6107 /* Set up node groups */
6109 init_sched_build_groups(*cpu_map
, cpu_map
,
6110 &cpu_to_allnodes_group
);
6112 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6113 /* Set up node groups */
6114 struct sched_group
*sg
, *prev
;
6115 cpumask_t nodemask
= node_to_cpumask(i
);
6116 cpumask_t domainspan
;
6117 cpumask_t covered
= CPU_MASK_NONE
;
6120 cpus_and(nodemask
, nodemask
, *cpu_map
);
6121 if (cpus_empty(nodemask
)) {
6122 sched_group_nodes
[i
] = NULL
;
6126 domainspan
= sched_domain_node_span(i
);
6127 cpus_and(domainspan
, domainspan
, *cpu_map
);
6129 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6131 printk(KERN_WARNING
"Can not alloc domain group for "
6135 sched_group_nodes
[i
] = sg
;
6136 for_each_cpu_mask(j
, nodemask
) {
6137 struct sched_domain
*sd
;
6139 sd
= &per_cpu(node_domains
, j
);
6142 sg
->__cpu_power
= 0;
6143 sg
->cpumask
= nodemask
;
6145 cpus_or(covered
, covered
, nodemask
);
6148 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6149 cpumask_t tmp
, notcovered
;
6150 int n
= (i
+ j
) % MAX_NUMNODES
;
6152 cpus_complement(notcovered
, covered
);
6153 cpus_and(tmp
, notcovered
, *cpu_map
);
6154 cpus_and(tmp
, tmp
, domainspan
);
6155 if (cpus_empty(tmp
))
6158 nodemask
= node_to_cpumask(n
);
6159 cpus_and(tmp
, tmp
, nodemask
);
6160 if (cpus_empty(tmp
))
6163 sg
= kmalloc_node(sizeof(struct sched_group
),
6167 "Can not alloc domain group for node %d\n", j
);
6170 sg
->__cpu_power
= 0;
6172 sg
->next
= prev
->next
;
6173 cpus_or(covered
, covered
, tmp
);
6180 /* Calculate CPU power for physical packages and nodes */
6181 #ifdef CONFIG_SCHED_SMT
6182 for_each_cpu_mask(i
, *cpu_map
) {
6183 struct sched_domain
*sd
= &per_cpu(cpu_domains
, i
);
6185 init_sched_groups_power(i
, sd
);
6188 #ifdef CONFIG_SCHED_MC
6189 for_each_cpu_mask(i
, *cpu_map
) {
6190 struct sched_domain
*sd
= &per_cpu(core_domains
, i
);
6192 init_sched_groups_power(i
, sd
);
6196 for_each_cpu_mask(i
, *cpu_map
) {
6197 struct sched_domain
*sd
= &per_cpu(phys_domains
, i
);
6199 init_sched_groups_power(i
, sd
);
6203 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6204 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6207 struct sched_group
*sg
;
6209 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6210 init_numa_sched_groups_power(sg
);
6214 /* Attach the domains */
6215 for_each_cpu_mask(i
, *cpu_map
) {
6216 struct sched_domain
*sd
;
6217 #ifdef CONFIG_SCHED_SMT
6218 sd
= &per_cpu(cpu_domains
, i
);
6219 #elif defined(CONFIG_SCHED_MC)
6220 sd
= &per_cpu(core_domains
, i
);
6222 sd
= &per_cpu(phys_domains
, i
);
6224 cpu_attach_domain(sd
, i
);
6231 free_sched_groups(cpu_map
);
6236 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6238 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6240 cpumask_t cpu_default_map
;
6244 * Setup mask for cpus without special case scheduling requirements.
6245 * For now this just excludes isolated cpus, but could be used to
6246 * exclude other special cases in the future.
6248 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
6250 err
= build_sched_domains(&cpu_default_map
);
6255 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6257 free_sched_groups(cpu_map
);
6261 * Detach sched domains from a group of cpus specified in cpu_map
6262 * These cpus will now be attached to the NULL domain
6264 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6268 for_each_cpu_mask(i
, *cpu_map
)
6269 cpu_attach_domain(NULL
, i
);
6270 synchronize_sched();
6271 arch_destroy_sched_domains(cpu_map
);
6275 * Partition sched domains as specified by the cpumasks below.
6276 * This attaches all cpus from the cpumasks to the NULL domain,
6277 * waits for a RCU quiescent period, recalculates sched
6278 * domain information and then attaches them back to the
6279 * correct sched domains
6280 * Call with hotplug lock held
6282 int partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
6284 cpumask_t change_map
;
6287 cpus_and(*partition1
, *partition1
, cpu_online_map
);
6288 cpus_and(*partition2
, *partition2
, cpu_online_map
);
6289 cpus_or(change_map
, *partition1
, *partition2
);
6291 /* Detach sched domains from all of the affected cpus */
6292 detach_destroy_domains(&change_map
);
6293 if (!cpus_empty(*partition1
))
6294 err
= build_sched_domains(partition1
);
6295 if (!err
&& !cpus_empty(*partition2
))
6296 err
= build_sched_domains(partition2
);
6301 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6302 static int arch_reinit_sched_domains(void)
6306 mutex_lock(&sched_hotcpu_mutex
);
6307 detach_destroy_domains(&cpu_online_map
);
6308 err
= arch_init_sched_domains(&cpu_online_map
);
6309 mutex_unlock(&sched_hotcpu_mutex
);
6314 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6318 if (buf
[0] != '0' && buf
[0] != '1')
6322 sched_smt_power_savings
= (buf
[0] == '1');
6324 sched_mc_power_savings
= (buf
[0] == '1');
6326 ret
= arch_reinit_sched_domains();
6328 return ret
? ret
: count
;
6331 #ifdef CONFIG_SCHED_MC
6332 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6334 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6336 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6337 const char *buf
, size_t count
)
6339 return sched_power_savings_store(buf
, count
, 0);
6341 static SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6342 sched_mc_power_savings_store
);
6345 #ifdef CONFIG_SCHED_SMT
6346 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6348 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6350 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6351 const char *buf
, size_t count
)
6353 return sched_power_savings_store(buf
, count
, 1);
6355 static SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6356 sched_smt_power_savings_store
);
6359 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6363 #ifdef CONFIG_SCHED_SMT
6365 err
= sysfs_create_file(&cls
->kset
.kobj
,
6366 &attr_sched_smt_power_savings
.attr
);
6368 #ifdef CONFIG_SCHED_MC
6369 if (!err
&& mc_capable())
6370 err
= sysfs_create_file(&cls
->kset
.kobj
,
6371 &attr_sched_mc_power_savings
.attr
);
6378 * Force a reinitialization of the sched domains hierarchy. The domains
6379 * and groups cannot be updated in place without racing with the balancing
6380 * code, so we temporarily attach all running cpus to the NULL domain
6381 * which will prevent rebalancing while the sched domains are recalculated.
6383 static int update_sched_domains(struct notifier_block
*nfb
,
6384 unsigned long action
, void *hcpu
)
6387 case CPU_UP_PREPARE
:
6388 case CPU_UP_PREPARE_FROZEN
:
6389 case CPU_DOWN_PREPARE
:
6390 case CPU_DOWN_PREPARE_FROZEN
:
6391 detach_destroy_domains(&cpu_online_map
);
6394 case CPU_UP_CANCELED
:
6395 case CPU_UP_CANCELED_FROZEN
:
6396 case CPU_DOWN_FAILED
:
6397 case CPU_DOWN_FAILED_FROZEN
:
6399 case CPU_ONLINE_FROZEN
:
6401 case CPU_DEAD_FROZEN
:
6403 * Fall through and re-initialise the domains.
6410 /* The hotplug lock is already held by cpu_up/cpu_down */
6411 arch_init_sched_domains(&cpu_online_map
);
6416 void __init
sched_init_smp(void)
6418 cpumask_t non_isolated_cpus
;
6420 mutex_lock(&sched_hotcpu_mutex
);
6421 arch_init_sched_domains(&cpu_online_map
);
6422 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6423 if (cpus_empty(non_isolated_cpus
))
6424 cpu_set(smp_processor_id(), non_isolated_cpus
);
6425 mutex_unlock(&sched_hotcpu_mutex
);
6426 /* XXX: Theoretical race here - CPU may be hotplugged now */
6427 hotcpu_notifier(update_sched_domains
, 0);
6429 init_sched_domain_sysctl();
6431 /* Move init over to a non-isolated CPU */
6432 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6436 void __init
sched_init_smp(void)
6439 #endif /* CONFIG_SMP */
6441 int in_sched_functions(unsigned long addr
)
6443 /* Linker adds these: start and end of __sched functions */
6444 extern char __sched_text_start
[], __sched_text_end
[];
6446 return in_lock_functions(addr
) ||
6447 (addr
>= (unsigned long)__sched_text_start
6448 && addr
< (unsigned long)__sched_text_end
);
6451 static inline void init_cfs_rq(struct cfs_rq
*cfs_rq
, struct rq
*rq
)
6453 cfs_rq
->tasks_timeline
= RB_ROOT
;
6454 cfs_rq
->fair_clock
= 1;
6455 #ifdef CONFIG_FAIR_GROUP_SCHED
6460 void __init
sched_init(void)
6462 int highest_cpu
= 0;
6466 * Link up the scheduling class hierarchy:
6468 rt_sched_class
.next
= &fair_sched_class
;
6469 fair_sched_class
.next
= &idle_sched_class
;
6470 idle_sched_class
.next
= NULL
;
6472 for_each_possible_cpu(i
) {
6473 struct rt_prio_array
*array
;
6477 spin_lock_init(&rq
->lock
);
6478 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6481 init_cfs_rq(&rq
->cfs
, rq
);
6482 #ifdef CONFIG_FAIR_GROUP_SCHED
6483 INIT_LIST_HEAD(&rq
->leaf_cfs_rq_list
);
6484 list_add(&rq
->cfs
.leaf_cfs_rq_list
, &rq
->leaf_cfs_rq_list
);
6487 for (j
= 0; j
< CPU_LOAD_IDX_MAX
; j
++)
6488 rq
->cpu_load
[j
] = 0;
6491 rq
->active_balance
= 0;
6492 rq
->next_balance
= jiffies
;
6495 rq
->migration_thread
= NULL
;
6496 INIT_LIST_HEAD(&rq
->migration_queue
);
6498 atomic_set(&rq
->nr_iowait
, 0);
6500 array
= &rq
->rt
.active
;
6501 for (j
= 0; j
< MAX_RT_PRIO
; j
++) {
6502 INIT_LIST_HEAD(array
->queue
+ j
);
6503 __clear_bit(j
, array
->bitmap
);
6506 /* delimiter for bitsearch: */
6507 __set_bit(MAX_RT_PRIO
, array
->bitmap
);
6510 set_load_weight(&init_task
);
6512 #ifdef CONFIG_PREEMPT_NOTIFIERS
6513 INIT_HLIST_HEAD(&init_task
.preempt_notifiers
);
6517 nr_cpu_ids
= highest_cpu
+ 1;
6518 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6521 #ifdef CONFIG_RT_MUTEXES
6522 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6526 * The boot idle thread does lazy MMU switching as well:
6528 atomic_inc(&init_mm
.mm_count
);
6529 enter_lazy_tlb(&init_mm
, current
);
6532 * Make us the idle thread. Technically, schedule() should not be
6533 * called from this thread, however somewhere below it might be,
6534 * but because we are the idle thread, we just pick up running again
6535 * when this runqueue becomes "idle".
6537 init_idle(current
, smp_processor_id());
6539 * During early bootup we pretend to be a normal task:
6541 current
->sched_class
= &fair_sched_class
;
6544 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6545 void __might_sleep(char *file
, int line
)
6548 static unsigned long prev_jiffy
; /* ratelimiting */
6550 if ((in_atomic() || irqs_disabled()) &&
6551 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6552 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6554 prev_jiffy
= jiffies
;
6555 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6556 " context at %s:%d\n", file
, line
);
6557 printk("in_atomic():%d, irqs_disabled():%d\n",
6558 in_atomic(), irqs_disabled());
6559 debug_show_held_locks(current
);
6560 if (irqs_disabled())
6561 print_irqtrace_events(current
);
6566 EXPORT_SYMBOL(__might_sleep
);
6569 #ifdef CONFIG_MAGIC_SYSRQ
6570 void normalize_rt_tasks(void)
6572 struct task_struct
*g
, *p
;
6573 unsigned long flags
;
6577 read_lock_irq(&tasklist_lock
);
6578 do_each_thread(g
, p
) {
6580 p
->se
.wait_runtime
= 0;
6581 p
->se
.exec_start
= 0;
6582 p
->se
.wait_start_fair
= 0;
6583 p
->se
.sleep_start_fair
= 0;
6584 #ifdef CONFIG_SCHEDSTATS
6585 p
->se
.wait_start
= 0;
6586 p
->se
.sleep_start
= 0;
6587 p
->se
.block_start
= 0;
6589 task_rq(p
)->cfs
.fair_clock
= 0;
6590 task_rq(p
)->clock
= 0;
6594 * Renice negative nice level userspace
6597 if (TASK_NICE(p
) < 0 && p
->mm
)
6598 set_user_nice(p
, 0);
6602 spin_lock_irqsave(&p
->pi_lock
, flags
);
6603 rq
= __task_rq_lock(p
);
6606 * Do not touch the migration thread:
6608 if (p
== rq
->migration_thread
)
6612 update_rq_clock(rq
);
6613 on_rq
= p
->se
.on_rq
;
6615 deactivate_task(rq
, p
, 0);
6616 __setscheduler(rq
, p
, SCHED_NORMAL
, 0);
6618 activate_task(rq
, p
, 0);
6619 resched_task(rq
->curr
);
6624 __task_rq_unlock(rq
);
6625 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
6626 } while_each_thread(g
, p
);
6628 read_unlock_irq(&tasklist_lock
);
6631 #endif /* CONFIG_MAGIC_SYSRQ */
6635 * These functions are only useful for the IA64 MCA handling.
6637 * They can only be called when the whole system has been
6638 * stopped - every CPU needs to be quiescent, and no scheduling
6639 * activity can take place. Using them for anything else would
6640 * be a serious bug, and as a result, they aren't even visible
6641 * under any other configuration.
6645 * curr_task - return the current task for a given cpu.
6646 * @cpu: the processor in question.
6648 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6650 struct task_struct
*curr_task(int cpu
)
6652 return cpu_curr(cpu
);
6656 * set_curr_task - set the current task for a given cpu.
6657 * @cpu: the processor in question.
6658 * @p: the task pointer to set.
6660 * Description: This function must only be used when non-maskable interrupts
6661 * are serviced on a separate stack. It allows the architecture to switch the
6662 * notion of the current task on a cpu in a non-blocking manner. This function
6663 * must be called with all CPU's synchronized, and interrupts disabled, the
6664 * and caller must save the original value of the current task (see
6665 * curr_task() above) and restore that value before reenabling interrupts and
6666 * re-starting the system.
6668 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6670 void set_curr_task(int cpu
, struct task_struct
*p
)