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
22 #include <linux/module.h>
23 #include <linux/nmi.h>
24 #include <linux/init.h>
25 #include <asm/uaccess.h>
26 #include <linux/highmem.h>
27 #include <linux/smp_lock.h>
28 #include <asm/mmu_context.h>
29 #include <linux/interrupt.h>
30 #include <linux/completion.h>
31 #include <linux/kernel_stat.h>
32 #include <linux/security.h>
33 #include <linux/notifier.h>
34 #include <linux/profile.h>
35 #include <linux/suspend.h>
36 #include <linux/blkdev.h>
37 #include <linux/delay.h>
38 #include <linux/smp.h>
39 #include <linux/threads.h>
40 #include <linux/timer.h>
41 #include <linux/rcupdate.h>
42 #include <linux/cpu.h>
43 #include <linux/cpuset.h>
44 #include <linux/percpu.h>
45 #include <linux/kthread.h>
46 #include <linux/seq_file.h>
47 #include <linux/syscalls.h>
48 #include <linux/times.h>
49 #include <linux/acct.h>
52 #include <asm/unistd.h>
55 * Convert user-nice values [ -20 ... 0 ... 19 ]
56 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
59 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
60 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
61 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
64 * 'User priority' is the nice value converted to something we
65 * can work with better when scaling various scheduler parameters,
66 * it's a [ 0 ... 39 ] range.
68 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
69 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
70 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
73 * Some helpers for converting nanosecond timing to jiffy resolution
75 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
76 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
79 * These are the 'tuning knobs' of the scheduler:
81 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
82 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
83 * Timeslices get refilled after they expire.
85 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
86 #define DEF_TIMESLICE (100 * HZ / 1000)
87 #define ON_RUNQUEUE_WEIGHT 30
88 #define CHILD_PENALTY 95
89 #define PARENT_PENALTY 100
91 #define PRIO_BONUS_RATIO 25
92 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
93 #define INTERACTIVE_DELTA 2
94 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
95 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
96 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
99 * If a task is 'interactive' then we reinsert it in the active
100 * array after it has expired its current timeslice. (it will not
101 * continue to run immediately, it will still roundrobin with
102 * other interactive tasks.)
104 * This part scales the interactivity limit depending on niceness.
106 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
107 * Here are a few examples of different nice levels:
109 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
110 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
111 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
112 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
113 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
115 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
116 * priority range a task can explore, a value of '1' means the
117 * task is rated interactive.)
119 * Ie. nice +19 tasks can never get 'interactive' enough to be
120 * reinserted into the active array. And only heavily CPU-hog nice -20
121 * tasks will be expired. Default nice 0 tasks are somewhere between,
122 * it takes some effort for them to get interactive, but it's not
126 #define CURRENT_BONUS(p) \
127 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
130 #define GRANULARITY (10 * HZ / 1000 ? : 1)
133 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
134 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
137 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
138 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
141 #define SCALE(v1,v1_max,v2_max) \
142 (v1) * (v2_max) / (v1_max)
145 (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
147 #define TASK_INTERACTIVE(p) \
148 ((p)->prio <= (p)->static_prio - DELTA(p))
150 #define INTERACTIVE_SLEEP(p) \
151 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
152 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
154 #define TASK_PREEMPTS_CURR(p, rq) \
155 ((p)->prio < (rq)->curr->prio)
158 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
159 * to time slice values: [800ms ... 100ms ... 5ms]
161 * The higher a thread's priority, the bigger timeslices
162 * it gets during one round of execution. But even the lowest
163 * priority thread gets MIN_TIMESLICE worth of execution time.
166 #define SCALE_PRIO(x, prio) \
167 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
169 static inline unsigned int task_timeslice(task_t
*p
)
171 if (p
->static_prio
< NICE_TO_PRIO(0))
172 return SCALE_PRIO(DEF_TIMESLICE
*4, p
->static_prio
);
174 return SCALE_PRIO(DEF_TIMESLICE
, p
->static_prio
);
176 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
177 < (long long) (sd)->cache_hot_time)
180 * These are the runqueue data structures:
183 #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
185 typedef struct runqueue runqueue_t
;
188 unsigned int nr_active
;
189 unsigned long bitmap
[BITMAP_SIZE
];
190 struct list_head queue
[MAX_PRIO
];
194 * This is the main, per-CPU runqueue data structure.
196 * Locking rule: those places that want to lock multiple runqueues
197 * (such as the load balancing or the thread migration code), lock
198 * acquire operations must be ordered by ascending &runqueue.
204 * nr_running and cpu_load should be in the same cacheline because
205 * remote CPUs use both these fields when doing load calculation.
207 unsigned long nr_running
;
209 unsigned long cpu_load
;
211 unsigned long long nr_switches
;
214 * This is part of a global counter where only the total sum
215 * over all CPUs matters. A task can increase this counter on
216 * one CPU and if it got migrated afterwards it may decrease
217 * it on another CPU. Always updated under the runqueue lock:
219 unsigned long nr_uninterruptible
;
221 unsigned long expired_timestamp
;
222 unsigned long long timestamp_last_tick
;
224 struct mm_struct
*prev_mm
;
225 prio_array_t
*active
, *expired
, arrays
[2];
226 int best_expired_prio
;
230 struct sched_domain
*sd
;
232 /* For active balancing */
236 task_t
*migration_thread
;
237 struct list_head migration_queue
;
240 #ifdef CONFIG_SCHEDSTATS
242 struct sched_info rq_sched_info
;
244 /* sys_sched_yield() stats */
245 unsigned long yld_exp_empty
;
246 unsigned long yld_act_empty
;
247 unsigned long yld_both_empty
;
248 unsigned long yld_cnt
;
250 /* schedule() stats */
251 unsigned long sched_switch
;
252 unsigned long sched_cnt
;
253 unsigned long sched_goidle
;
255 /* try_to_wake_up() stats */
256 unsigned long ttwu_cnt
;
257 unsigned long ttwu_local
;
261 static DEFINE_PER_CPU(struct runqueue
, runqueues
);
263 #define for_each_domain(cpu, domain) \
264 for (domain = cpu_rq(cpu)->sd; domain; domain = domain->parent)
266 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
267 #define this_rq() (&__get_cpu_var(runqueues))
268 #define task_rq(p) cpu_rq(task_cpu(p))
269 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
272 * Default context-switch locking:
274 #ifndef prepare_arch_switch
275 # define prepare_arch_switch(rq, next) do { } while (0)
276 # define finish_arch_switch(rq, next) spin_unlock_irq(&(rq)->lock)
277 # define task_running(rq, p) ((rq)->curr == (p))
281 * task_rq_lock - lock the runqueue a given task resides on and disable
282 * interrupts. Note the ordering: we can safely lookup the task_rq without
283 * explicitly disabling preemption.
285 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
291 local_irq_save(*flags
);
293 spin_lock(&rq
->lock
);
294 if (unlikely(rq
!= task_rq(p
))) {
295 spin_unlock_irqrestore(&rq
->lock
, *flags
);
296 goto repeat_lock_task
;
301 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
304 spin_unlock_irqrestore(&rq
->lock
, *flags
);
307 #ifdef CONFIG_SCHEDSTATS
309 * bump this up when changing the output format or the meaning of an existing
310 * format, so that tools can adapt (or abort)
312 #define SCHEDSTAT_VERSION 11
314 static int show_schedstat(struct seq_file
*seq
, void *v
)
318 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
319 seq_printf(seq
, "timestamp %lu\n", jiffies
);
320 for_each_online_cpu(cpu
) {
321 runqueue_t
*rq
= cpu_rq(cpu
);
323 struct sched_domain
*sd
;
327 /* runqueue-specific stats */
329 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
330 cpu
, rq
->yld_both_empty
,
331 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
332 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
333 rq
->ttwu_cnt
, rq
->ttwu_local
,
334 rq
->rq_sched_info
.cpu_time
,
335 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
337 seq_printf(seq
, "\n");
340 /* domain-specific stats */
341 for_each_domain(cpu
, sd
) {
342 enum idle_type itype
;
343 char mask_str
[NR_CPUS
];
345 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
346 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
347 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
349 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
351 sd
->lb_balanced
[itype
],
352 sd
->lb_failed
[itype
],
353 sd
->lb_imbalance
[itype
],
354 sd
->lb_gained
[itype
],
355 sd
->lb_hot_gained
[itype
],
356 sd
->lb_nobusyq
[itype
],
357 sd
->lb_nobusyg
[itype
]);
359 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu\n",
360 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
361 sd
->sbe_pushed
, sd
->sbe_attempts
,
362 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
369 static int schedstat_open(struct inode
*inode
, struct file
*file
)
371 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
372 char *buf
= kmalloc(size
, GFP_KERNEL
);
378 res
= single_open(file
, show_schedstat
, NULL
);
380 m
= file
->private_data
;
388 struct file_operations proc_schedstat_operations
= {
389 .open
= schedstat_open
,
392 .release
= single_release
,
395 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
396 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
397 #else /* !CONFIG_SCHEDSTATS */
398 # define schedstat_inc(rq, field) do { } while (0)
399 # define schedstat_add(rq, field, amt) do { } while (0)
403 * rq_lock - lock a given runqueue and disable interrupts.
405 static inline runqueue_t
*this_rq_lock(void)
412 spin_lock(&rq
->lock
);
417 #ifdef CONFIG_SCHED_SMT
418 static int cpu_and_siblings_are_idle(int cpu
)
421 for_each_cpu_mask(sib
, cpu_sibling_map
[cpu
]) {
430 #define cpu_and_siblings_are_idle(A) idle_cpu(A)
433 #ifdef CONFIG_SCHEDSTATS
435 * Called when a process is dequeued from the active array and given
436 * the cpu. We should note that with the exception of interactive
437 * tasks, the expired queue will become the active queue after the active
438 * queue is empty, without explicitly dequeuing and requeuing tasks in the
439 * expired queue. (Interactive tasks may be requeued directly to the
440 * active queue, thus delaying tasks in the expired queue from running;
441 * see scheduler_tick()).
443 * This function is only called from sched_info_arrive(), rather than
444 * dequeue_task(). Even though a task may be queued and dequeued multiple
445 * times as it is shuffled about, we're really interested in knowing how
446 * long it was from the *first* time it was queued to the time that it
449 static inline void sched_info_dequeued(task_t
*t
)
451 t
->sched_info
.last_queued
= 0;
455 * Called when a task finally hits the cpu. We can now calculate how
456 * long it was waiting to run. We also note when it began so that we
457 * can keep stats on how long its timeslice is.
459 static inline void sched_info_arrive(task_t
*t
)
461 unsigned long now
= jiffies
, diff
= 0;
462 struct runqueue
*rq
= task_rq(t
);
464 if (t
->sched_info
.last_queued
)
465 diff
= now
- t
->sched_info
.last_queued
;
466 sched_info_dequeued(t
);
467 t
->sched_info
.run_delay
+= diff
;
468 t
->sched_info
.last_arrival
= now
;
469 t
->sched_info
.pcnt
++;
474 rq
->rq_sched_info
.run_delay
+= diff
;
475 rq
->rq_sched_info
.pcnt
++;
479 * Called when a process is queued into either the active or expired
480 * array. The time is noted and later used to determine how long we
481 * had to wait for us to reach the cpu. Since the expired queue will
482 * become the active queue after active queue is empty, without dequeuing
483 * and requeuing any tasks, we are interested in queuing to either. It
484 * is unusual but not impossible for tasks to be dequeued and immediately
485 * requeued in the same or another array: this can happen in sched_yield(),
486 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
489 * This function is only called from enqueue_task(), but also only updates
490 * the timestamp if it is already not set. It's assumed that
491 * sched_info_dequeued() will clear that stamp when appropriate.
493 static inline void sched_info_queued(task_t
*t
)
495 if (!t
->sched_info
.last_queued
)
496 t
->sched_info
.last_queued
= jiffies
;
500 * Called when a process ceases being the active-running process, either
501 * voluntarily or involuntarily. Now we can calculate how long we ran.
503 static inline void sched_info_depart(task_t
*t
)
505 struct runqueue
*rq
= task_rq(t
);
506 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
508 t
->sched_info
.cpu_time
+= diff
;
511 rq
->rq_sched_info
.cpu_time
+= diff
;
515 * Called when tasks are switched involuntarily due, typically, to expiring
516 * their time slice. (This may also be called when switching to or from
517 * the idle task.) We are only called when prev != next.
519 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
521 struct runqueue
*rq
= task_rq(prev
);
524 * prev now departs the cpu. It's not interesting to record
525 * stats about how efficient we were at scheduling the idle
528 if (prev
!= rq
->idle
)
529 sched_info_depart(prev
);
531 if (next
!= rq
->idle
)
532 sched_info_arrive(next
);
535 #define sched_info_queued(t) do { } while (0)
536 #define sched_info_switch(t, next) do { } while (0)
537 #endif /* CONFIG_SCHEDSTATS */
540 * Adding/removing a task to/from a priority array:
542 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
545 list_del(&p
->run_list
);
546 if (list_empty(array
->queue
+ p
->prio
))
547 __clear_bit(p
->prio
, array
->bitmap
);
550 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
552 sched_info_queued(p
);
553 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
554 __set_bit(p
->prio
, array
->bitmap
);
560 * Put task to the end of the run list without the overhead of dequeue
561 * followed by enqueue.
563 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
565 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
568 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
570 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
571 __set_bit(p
->prio
, array
->bitmap
);
577 * effective_prio - return the priority that is based on the static
578 * priority but is modified by bonuses/penalties.
580 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
581 * into the -5 ... 0 ... +5 bonus/penalty range.
583 * We use 25% of the full 0...39 priority range so that:
585 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
586 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
588 * Both properties are important to certain workloads.
590 static int effective_prio(task_t
*p
)
597 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
599 prio
= p
->static_prio
- bonus
;
600 if (prio
< MAX_RT_PRIO
)
602 if (prio
> MAX_PRIO
-1)
608 * __activate_task - move a task to the runqueue.
610 static inline void __activate_task(task_t
*p
, runqueue_t
*rq
)
612 enqueue_task(p
, rq
->active
);
617 * __activate_idle_task - move idle task to the _front_ of runqueue.
619 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
621 enqueue_task_head(p
, rq
->active
);
625 static void recalc_task_prio(task_t
*p
, unsigned long long now
)
627 /* Caller must always ensure 'now >= p->timestamp' */
628 unsigned long long __sleep_time
= now
- p
->timestamp
;
629 unsigned long sleep_time
;
631 if (__sleep_time
> NS_MAX_SLEEP_AVG
)
632 sleep_time
= NS_MAX_SLEEP_AVG
;
634 sleep_time
= (unsigned long)__sleep_time
;
636 if (likely(sleep_time
> 0)) {
638 * User tasks that sleep a long time are categorised as
639 * idle and will get just interactive status to stay active &
640 * prevent them suddenly becoming cpu hogs and starving
643 if (p
->mm
&& p
->activated
!= -1 &&
644 sleep_time
> INTERACTIVE_SLEEP(p
)) {
645 p
->sleep_avg
= JIFFIES_TO_NS(MAX_SLEEP_AVG
-
649 * The lower the sleep avg a task has the more
650 * rapidly it will rise with sleep time.
652 sleep_time
*= (MAX_BONUS
- CURRENT_BONUS(p
)) ? : 1;
655 * Tasks waking from uninterruptible sleep are
656 * limited in their sleep_avg rise as they
657 * are likely to be waiting on I/O
659 if (p
->activated
== -1 && p
->mm
) {
660 if (p
->sleep_avg
>= INTERACTIVE_SLEEP(p
))
662 else if (p
->sleep_avg
+ sleep_time
>=
663 INTERACTIVE_SLEEP(p
)) {
664 p
->sleep_avg
= INTERACTIVE_SLEEP(p
);
670 * This code gives a bonus to interactive tasks.
672 * The boost works by updating the 'average sleep time'
673 * value here, based on ->timestamp. The more time a
674 * task spends sleeping, the higher the average gets -
675 * and the higher the priority boost gets as well.
677 p
->sleep_avg
+= sleep_time
;
679 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
680 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
684 p
->prio
= effective_prio(p
);
688 * activate_task - move a task to the runqueue and do priority recalculation
690 * Update all the scheduling statistics stuff. (sleep average
691 * calculation, priority modifiers, etc.)
693 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
695 unsigned long long now
;
700 /* Compensate for drifting sched_clock */
701 runqueue_t
*this_rq
= this_rq();
702 now
= (now
- this_rq
->timestamp_last_tick
)
703 + rq
->timestamp_last_tick
;
707 recalc_task_prio(p
, now
);
710 * This checks to make sure it's not an uninterruptible task
711 * that is now waking up.
715 * Tasks which were woken up by interrupts (ie. hw events)
716 * are most likely of interactive nature. So we give them
717 * the credit of extending their sleep time to the period
718 * of time they spend on the runqueue, waiting for execution
719 * on a CPU, first time around:
725 * Normal first-time wakeups get a credit too for
726 * on-runqueue time, but it will be weighted down:
733 __activate_task(p
, rq
);
737 * deactivate_task - remove a task from the runqueue.
739 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
742 dequeue_task(p
, p
->array
);
747 * resched_task - mark a task 'to be rescheduled now'.
749 * On UP this means the setting of the need_resched flag, on SMP it
750 * might also involve a cross-CPU call to trigger the scheduler on
754 static void resched_task(task_t
*p
)
756 int need_resched
, nrpolling
;
758 assert_spin_locked(&task_rq(p
)->lock
);
760 /* minimise the chance of sending an interrupt to poll_idle() */
761 nrpolling
= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
762 need_resched
= test_and_set_tsk_thread_flag(p
,TIF_NEED_RESCHED
);
763 nrpolling
|= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
765 if (!need_resched
&& !nrpolling
&& (task_cpu(p
) != smp_processor_id()))
766 smp_send_reschedule(task_cpu(p
));
769 static inline void resched_task(task_t
*p
)
771 set_tsk_need_resched(p
);
776 * task_curr - is this task currently executing on a CPU?
777 * @p: the task in question.
779 inline int task_curr(const task_t
*p
)
781 return cpu_curr(task_cpu(p
)) == p
;
791 struct list_head list
;
792 enum request_type type
;
794 /* For REQ_MOVE_TASK */
798 /* For REQ_SET_DOMAIN */
799 struct sched_domain
*sd
;
801 struct completion done
;
805 * The task's runqueue lock must be held.
806 * Returns true if you have to wait for migration thread.
808 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
810 runqueue_t
*rq
= task_rq(p
);
813 * If the task is not on a runqueue (and not running), then
814 * it is sufficient to simply update the task's cpu field.
816 if (!p
->array
&& !task_running(rq
, p
)) {
817 set_task_cpu(p
, dest_cpu
);
821 init_completion(&req
->done
);
822 req
->type
= REQ_MOVE_TASK
;
824 req
->dest_cpu
= dest_cpu
;
825 list_add(&req
->list
, &rq
->migration_queue
);
830 * wait_task_inactive - wait for a thread to unschedule.
832 * The caller must ensure that the task *will* unschedule sometime soon,
833 * else this function might spin for a *long* time. This function can't
834 * be called with interrupts off, or it may introduce deadlock with
835 * smp_call_function() if an IPI is sent by the same process we are
836 * waiting to become inactive.
838 void wait_task_inactive(task_t
* p
)
845 rq
= task_rq_lock(p
, &flags
);
846 /* Must be off runqueue entirely, not preempted. */
847 if (unlikely(p
->array
|| task_running(rq
, p
))) {
848 /* If it's preempted, we yield. It could be a while. */
849 preempted
= !task_running(rq
, p
);
850 task_rq_unlock(rq
, &flags
);
856 task_rq_unlock(rq
, &flags
);
860 * kick_process - kick a running thread to enter/exit the kernel
861 * @p: the to-be-kicked thread
863 * Cause a process which is running on another CPU to enter
864 * kernel-mode, without any delay. (to get signals handled.)
866 * NOTE: this function doesnt have to take the runqueue lock,
867 * because all it wants to ensure is that the remote task enters
868 * the kernel. If the IPI races and the task has been migrated
869 * to another CPU then no harm is done and the purpose has been
872 void kick_process(task_t
*p
)
878 if ((cpu
!= smp_processor_id()) && task_curr(p
))
879 smp_send_reschedule(cpu
);
884 * Return a low guess at the load of a migration-source cpu.
886 * We want to under-estimate the load of migration sources, to
887 * balance conservatively.
889 static inline unsigned long source_load(int cpu
)
891 runqueue_t
*rq
= cpu_rq(cpu
);
892 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
894 return min(rq
->cpu_load
, load_now
);
898 * Return a high guess at the load of a migration-target cpu
900 static inline unsigned long target_load(int cpu
)
902 runqueue_t
*rq
= cpu_rq(cpu
);
903 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
905 return max(rq
->cpu_load
, load_now
);
911 * wake_idle() will wake a task on an idle cpu if task->cpu is
912 * not idle and an idle cpu is available. The span of cpus to
913 * search starts with cpus closest then further out as needed,
914 * so we always favor a closer, idle cpu.
916 * Returns the CPU we should wake onto.
918 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
919 static int wake_idle(int cpu
, task_t
*p
)
922 struct sched_domain
*sd
;
928 for_each_domain(cpu
, sd
) {
929 if (sd
->flags
& SD_WAKE_IDLE
) {
930 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
931 for_each_cpu_mask(i
, tmp
) {
942 static inline int wake_idle(int cpu
, task_t
*p
)
949 * try_to_wake_up - wake up a thread
950 * @p: the to-be-woken-up thread
951 * @state: the mask of task states that can be woken
952 * @sync: do a synchronous wakeup?
954 * Put it on the run-queue if it's not already there. The "current"
955 * thread is always on the run-queue (except when the actual
956 * re-schedule is in progress), and as such you're allowed to do
957 * the simpler "current->state = TASK_RUNNING" to mark yourself
958 * runnable without the overhead of this.
960 * returns failure only if the task is already active.
962 static int try_to_wake_up(task_t
* p
, unsigned int state
, int sync
)
964 int cpu
, this_cpu
, success
= 0;
969 unsigned long load
, this_load
;
970 struct sched_domain
*sd
;
974 rq
= task_rq_lock(p
, &flags
);
975 old_state
= p
->state
;
976 if (!(old_state
& state
))
983 this_cpu
= smp_processor_id();
986 if (unlikely(task_running(rq
, p
)))
989 #ifdef CONFIG_SCHEDSTATS
990 schedstat_inc(rq
, ttwu_cnt
);
991 if (cpu
== this_cpu
) {
992 schedstat_inc(rq
, ttwu_local
);
994 for_each_domain(this_cpu
, sd
) {
995 if (cpu_isset(cpu
, sd
->span
)) {
996 schedstat_inc(sd
, ttwu_wake_remote
);
1004 if (cpu
== this_cpu
|| unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1007 load
= source_load(cpu
);
1008 this_load
= target_load(this_cpu
);
1011 * If sync wakeup then subtract the (maximum possible) effect of
1012 * the currently running task from the load of the current CPU:
1015 this_load
-= SCHED_LOAD_SCALE
;
1017 /* Don't pull the task off an idle CPU to a busy one */
1018 if (load
< SCHED_LOAD_SCALE
/2 && this_load
> SCHED_LOAD_SCALE
/2)
1021 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1024 * Scan domains for affine wakeup and passive balancing
1027 for_each_domain(this_cpu
, sd
) {
1028 unsigned int imbalance
;
1030 * Start passive balancing when half the imbalance_pct
1033 imbalance
= sd
->imbalance_pct
+ (sd
->imbalance_pct
- 100) / 2;
1035 if ((sd
->flags
& SD_WAKE_AFFINE
) &&
1036 !task_hot(p
, rq
->timestamp_last_tick
, sd
)) {
1038 * This domain has SD_WAKE_AFFINE and p is cache cold
1041 if (cpu_isset(cpu
, sd
->span
)) {
1042 schedstat_inc(sd
, ttwu_move_affine
);
1045 } else if ((sd
->flags
& SD_WAKE_BALANCE
) &&
1046 imbalance
*this_load
<= 100*load
) {
1048 * This domain has SD_WAKE_BALANCE and there is
1051 if (cpu_isset(cpu
, sd
->span
)) {
1052 schedstat_inc(sd
, ttwu_move_balance
);
1058 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1060 new_cpu
= wake_idle(new_cpu
, p
);
1061 if (new_cpu
!= cpu
) {
1062 set_task_cpu(p
, new_cpu
);
1063 task_rq_unlock(rq
, &flags
);
1064 /* might preempt at this point */
1065 rq
= task_rq_lock(p
, &flags
);
1066 old_state
= p
->state
;
1067 if (!(old_state
& state
))
1072 this_cpu
= smp_processor_id();
1077 #endif /* CONFIG_SMP */
1078 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1079 rq
->nr_uninterruptible
--;
1081 * Tasks on involuntary sleep don't earn
1082 * sleep_avg beyond just interactive state.
1088 * Sync wakeups (i.e. those types of wakeups where the waker
1089 * has indicated that it will leave the CPU in short order)
1090 * don't trigger a preemption, if the woken up task will run on
1091 * this cpu. (in this case the 'I will reschedule' promise of
1092 * the waker guarantees that the freshly woken up task is going
1093 * to be considered on this CPU.)
1095 activate_task(p
, rq
, cpu
== this_cpu
);
1096 if (!sync
|| cpu
!= this_cpu
) {
1097 if (TASK_PREEMPTS_CURR(p
, rq
))
1098 resched_task(rq
->curr
);
1103 p
->state
= TASK_RUNNING
;
1105 task_rq_unlock(rq
, &flags
);
1110 int fastcall
wake_up_process(task_t
* p
)
1112 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1113 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1116 EXPORT_SYMBOL(wake_up_process
);
1118 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1120 return try_to_wake_up(p
, state
, 0);
1124 static int find_idlest_cpu(struct task_struct
*p
, int this_cpu
,
1125 struct sched_domain
*sd
);
1129 * Perform scheduler related setup for a newly forked process p.
1130 * p is forked by current.
1132 void fastcall
sched_fork(task_t
*p
)
1135 * We mark the process as running here, but have not actually
1136 * inserted it onto the runqueue yet. This guarantees that
1137 * nobody will actually run it, and a signal or other external
1138 * event cannot wake it up and insert it on the runqueue either.
1140 p
->state
= TASK_RUNNING
;
1141 INIT_LIST_HEAD(&p
->run_list
);
1143 spin_lock_init(&p
->switch_lock
);
1144 #ifdef CONFIG_SCHEDSTATS
1145 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1147 #ifdef CONFIG_PREEMPT
1149 * During context-switch we hold precisely one spinlock, which
1150 * schedule_tail drops. (in the common case it's this_rq()->lock,
1151 * but it also can be p->switch_lock.) So we compensate with a count
1152 * of 1. Also, we want to start with kernel preemption disabled.
1154 p
->thread_info
->preempt_count
= 1;
1157 * Share the timeslice between parent and child, thus the
1158 * total amount of pending timeslices in the system doesn't change,
1159 * resulting in more scheduling fairness.
1161 local_irq_disable();
1162 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1164 * The remainder of the first timeslice might be recovered by
1165 * the parent if the child exits early enough.
1167 p
->first_time_slice
= 1;
1168 current
->time_slice
>>= 1;
1169 p
->timestamp
= sched_clock();
1170 if (unlikely(!current
->time_slice
)) {
1172 * This case is rare, it happens when the parent has only
1173 * a single jiffy left from its timeslice. Taking the
1174 * runqueue lock is not a problem.
1176 current
->time_slice
= 1;
1186 * wake_up_new_task - wake up a newly created task for the first time.
1188 * This function will do some initial scheduler statistics housekeeping
1189 * that must be done for every newly created context, then puts the task
1190 * on the runqueue and wakes it.
1192 void fastcall
wake_up_new_task(task_t
* p
, unsigned long clone_flags
)
1194 unsigned long flags
;
1196 runqueue_t
*rq
, *this_rq
;
1198 rq
= task_rq_lock(p
, &flags
);
1200 this_cpu
= smp_processor_id();
1202 BUG_ON(p
->state
!= TASK_RUNNING
);
1205 * We decrease the sleep average of forking parents
1206 * and children as well, to keep max-interactive tasks
1207 * from forking tasks that are max-interactive. The parent
1208 * (current) is done further down, under its lock.
1210 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1211 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1213 p
->prio
= effective_prio(p
);
1215 if (likely(cpu
== this_cpu
)) {
1216 if (!(clone_flags
& CLONE_VM
)) {
1218 * The VM isn't cloned, so we're in a good position to
1219 * do child-runs-first in anticipation of an exec. This
1220 * usually avoids a lot of COW overhead.
1222 if (unlikely(!current
->array
))
1223 __activate_task(p
, rq
);
1225 p
->prio
= current
->prio
;
1226 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1227 p
->array
= current
->array
;
1228 p
->array
->nr_active
++;
1233 /* Run child last */
1234 __activate_task(p
, rq
);
1236 * We skip the following code due to cpu == this_cpu
1238 * task_rq_unlock(rq, &flags);
1239 * this_rq = task_rq_lock(current, &flags);
1243 this_rq
= cpu_rq(this_cpu
);
1246 * Not the local CPU - must adjust timestamp. This should
1247 * get optimised away in the !CONFIG_SMP case.
1249 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1250 + rq
->timestamp_last_tick
;
1251 __activate_task(p
, rq
);
1252 if (TASK_PREEMPTS_CURR(p
, rq
))
1253 resched_task(rq
->curr
);
1256 * Parent and child are on different CPUs, now get the
1257 * parent runqueue to update the parent's ->sleep_avg:
1259 task_rq_unlock(rq
, &flags
);
1260 this_rq
= task_rq_lock(current
, &flags
);
1262 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1263 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1264 task_rq_unlock(this_rq
, &flags
);
1268 * Potentially available exiting-child timeslices are
1269 * retrieved here - this way the parent does not get
1270 * penalized for creating too many threads.
1272 * (this cannot be used to 'generate' timeslices
1273 * artificially, because any timeslice recovered here
1274 * was given away by the parent in the first place.)
1276 void fastcall
sched_exit(task_t
* p
)
1278 unsigned long flags
;
1282 * If the child was a (relative-) CPU hog then decrease
1283 * the sleep_avg of the parent as well.
1285 rq
= task_rq_lock(p
->parent
, &flags
);
1286 if (p
->first_time_slice
) {
1287 p
->parent
->time_slice
+= p
->time_slice
;
1288 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1289 p
->parent
->time_slice
= task_timeslice(p
);
1291 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1292 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1293 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1295 task_rq_unlock(rq
, &flags
);
1299 * finish_task_switch - clean up after a task-switch
1300 * @prev: the thread we just switched away from.
1302 * We enter this with the runqueue still locked, and finish_arch_switch()
1303 * will unlock it along with doing any other architecture-specific cleanup
1306 * Note that we may have delayed dropping an mm in context_switch(). If
1307 * so, we finish that here outside of the runqueue lock. (Doing it
1308 * with the lock held can cause deadlocks; see schedule() for
1311 static inline void finish_task_switch(task_t
*prev
)
1312 __releases(rq
->lock
)
1314 runqueue_t
*rq
= this_rq();
1315 struct mm_struct
*mm
= rq
->prev_mm
;
1316 unsigned long prev_task_flags
;
1321 * A task struct has one reference for the use as "current".
1322 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1323 * calls schedule one last time. The schedule call will never return,
1324 * and the scheduled task must drop that reference.
1325 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1326 * still held, otherwise prev could be scheduled on another cpu, die
1327 * there before we look at prev->state, and then the reference would
1329 * Manfred Spraul <manfred@colorfullife.com>
1331 prev_task_flags
= prev
->flags
;
1332 finish_arch_switch(rq
, prev
);
1335 if (unlikely(prev_task_flags
& PF_DEAD
))
1336 put_task_struct(prev
);
1340 * schedule_tail - first thing a freshly forked thread must call.
1341 * @prev: the thread we just switched away from.
1343 asmlinkage
void schedule_tail(task_t
*prev
)
1344 __releases(rq
->lock
)
1346 finish_task_switch(prev
);
1348 if (current
->set_child_tid
)
1349 put_user(current
->pid
, current
->set_child_tid
);
1353 * context_switch - switch to the new MM and the new
1354 * thread's register state.
1357 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1359 struct mm_struct
*mm
= next
->mm
;
1360 struct mm_struct
*oldmm
= prev
->active_mm
;
1362 if (unlikely(!mm
)) {
1363 next
->active_mm
= oldmm
;
1364 atomic_inc(&oldmm
->mm_count
);
1365 enter_lazy_tlb(oldmm
, next
);
1367 switch_mm(oldmm
, mm
, next
);
1369 if (unlikely(!prev
->mm
)) {
1370 prev
->active_mm
= NULL
;
1371 WARN_ON(rq
->prev_mm
);
1372 rq
->prev_mm
= oldmm
;
1375 /* Here we just switch the register state and the stack. */
1376 switch_to(prev
, next
, prev
);
1382 * nr_running, nr_uninterruptible and nr_context_switches:
1384 * externally visible scheduler statistics: current number of runnable
1385 * threads, current number of uninterruptible-sleeping threads, total
1386 * number of context switches performed since bootup.
1388 unsigned long nr_running(void)
1390 unsigned long i
, sum
= 0;
1392 for_each_online_cpu(i
)
1393 sum
+= cpu_rq(i
)->nr_running
;
1398 unsigned long nr_uninterruptible(void)
1400 unsigned long i
, sum
= 0;
1403 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1406 * Since we read the counters lockless, it might be slightly
1407 * inaccurate. Do not allow it to go below zero though:
1409 if (unlikely((long)sum
< 0))
1415 unsigned long long nr_context_switches(void)
1417 unsigned long long i
, sum
= 0;
1420 sum
+= cpu_rq(i
)->nr_switches
;
1425 unsigned long nr_iowait(void)
1427 unsigned long i
, sum
= 0;
1430 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1438 * double_rq_lock - safely lock two runqueues
1440 * Note this does not disable interrupts like task_rq_lock,
1441 * you need to do so manually before calling.
1443 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1444 __acquires(rq1
->lock
)
1445 __acquires(rq2
->lock
)
1448 spin_lock(&rq1
->lock
);
1449 __acquire(rq2
->lock
); /* Fake it out ;) */
1452 spin_lock(&rq1
->lock
);
1453 spin_lock(&rq2
->lock
);
1455 spin_lock(&rq2
->lock
);
1456 spin_lock(&rq1
->lock
);
1462 * double_rq_unlock - safely unlock two runqueues
1464 * Note this does not restore interrupts like task_rq_unlock,
1465 * you need to do so manually after calling.
1467 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1468 __releases(rq1
->lock
)
1469 __releases(rq2
->lock
)
1471 spin_unlock(&rq1
->lock
);
1473 spin_unlock(&rq2
->lock
);
1475 __release(rq2
->lock
);
1479 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1481 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1482 __releases(this_rq
->lock
)
1483 __acquires(busiest
->lock
)
1484 __acquires(this_rq
->lock
)
1486 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1487 if (busiest
< this_rq
) {
1488 spin_unlock(&this_rq
->lock
);
1489 spin_lock(&busiest
->lock
);
1490 spin_lock(&this_rq
->lock
);
1492 spin_lock(&busiest
->lock
);
1497 * find_idlest_cpu - find the least busy runqueue.
1499 static int find_idlest_cpu(struct task_struct
*p
, int this_cpu
,
1500 struct sched_domain
*sd
)
1502 unsigned long load
, min_load
, this_load
;
1507 min_load
= ULONG_MAX
;
1509 cpus_and(mask
, sd
->span
, p
->cpus_allowed
);
1511 for_each_cpu_mask(i
, mask
) {
1512 load
= target_load(i
);
1514 if (load
< min_load
) {
1518 /* break out early on an idle CPU: */
1524 /* add +1 to account for the new task */
1525 this_load
= source_load(this_cpu
) + SCHED_LOAD_SCALE
;
1528 * Would with the addition of the new task to the
1529 * current CPU there be an imbalance between this
1530 * CPU and the idlest CPU?
1532 * Use half of the balancing threshold - new-context is
1533 * a good opportunity to balance.
1535 if (min_load
*(100 + (sd
->imbalance_pct
-100)/2) < this_load
*100)
1542 * If dest_cpu is allowed for this process, migrate the task to it.
1543 * This is accomplished by forcing the cpu_allowed mask to only
1544 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1545 * the cpu_allowed mask is restored.
1547 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1549 migration_req_t req
;
1551 unsigned long flags
;
1553 rq
= task_rq_lock(p
, &flags
);
1554 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1555 || unlikely(cpu_is_offline(dest_cpu
)))
1558 /* force the process onto the specified CPU */
1559 if (migrate_task(p
, dest_cpu
, &req
)) {
1560 /* Need to wait for migration thread (might exit: take ref). */
1561 struct task_struct
*mt
= rq
->migration_thread
;
1562 get_task_struct(mt
);
1563 task_rq_unlock(rq
, &flags
);
1564 wake_up_process(mt
);
1565 put_task_struct(mt
);
1566 wait_for_completion(&req
.done
);
1570 task_rq_unlock(rq
, &flags
);
1574 * sched_exec(): find the highest-level, exec-balance-capable
1575 * domain and try to migrate the task to the least loaded CPU.
1577 * execve() is a valuable balancing opportunity, because at this point
1578 * the task has the smallest effective memory and cache footprint.
1580 void sched_exec(void)
1582 struct sched_domain
*tmp
, *sd
= NULL
;
1583 int new_cpu
, this_cpu
= get_cpu();
1585 /* Prefer the current CPU if there's only this task running */
1586 if (this_rq()->nr_running
<= 1)
1589 for_each_domain(this_cpu
, tmp
)
1590 if (tmp
->flags
& SD_BALANCE_EXEC
)
1594 schedstat_inc(sd
, sbe_attempts
);
1595 new_cpu
= find_idlest_cpu(current
, this_cpu
, sd
);
1596 if (new_cpu
!= this_cpu
) {
1597 schedstat_inc(sd
, sbe_pushed
);
1599 sched_migrate_task(current
, new_cpu
);
1608 * pull_task - move a task from a remote runqueue to the local runqueue.
1609 * Both runqueues must be locked.
1612 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1613 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1615 dequeue_task(p
, src_array
);
1616 src_rq
->nr_running
--;
1617 set_task_cpu(p
, this_cpu
);
1618 this_rq
->nr_running
++;
1619 enqueue_task(p
, this_array
);
1620 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1621 + this_rq
->timestamp_last_tick
;
1623 * Note that idle threads have a prio of MAX_PRIO, for this test
1624 * to be always true for them.
1626 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1627 resched_task(this_rq
->curr
);
1631 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1634 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1635 struct sched_domain
*sd
, enum idle_type idle
, int *all_pinned
)
1638 * We do not migrate tasks that are:
1639 * 1) running (obviously), or
1640 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1641 * 3) are cache-hot on their current CPU.
1643 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1647 if (task_running(rq
, p
))
1651 * Aggressive migration if:
1652 * 1) the [whole] cpu is idle, or
1653 * 2) too many balance attempts have failed.
1656 if (cpu_and_siblings_are_idle(this_cpu
) || \
1657 sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1660 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1666 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1667 * as part of a balancing operation within "domain". Returns the number of
1670 * Called with both runqueues locked.
1672 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1673 unsigned long max_nr_move
, struct sched_domain
*sd
,
1674 enum idle_type idle
, int *all_pinned
)
1676 prio_array_t
*array
, *dst_array
;
1677 struct list_head
*head
, *curr
;
1678 int idx
, pulled
= 0, pinned
= 0;
1681 if (max_nr_move
== 0)
1687 * We first consider expired tasks. Those will likely not be
1688 * executed in the near future, and they are most likely to
1689 * be cache-cold, thus switching CPUs has the least effect
1692 if (busiest
->expired
->nr_active
) {
1693 array
= busiest
->expired
;
1694 dst_array
= this_rq
->expired
;
1696 array
= busiest
->active
;
1697 dst_array
= this_rq
->active
;
1701 /* Start searching at priority 0: */
1705 idx
= sched_find_first_bit(array
->bitmap
);
1707 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1708 if (idx
>= MAX_PRIO
) {
1709 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1710 array
= busiest
->active
;
1711 dst_array
= this_rq
->active
;
1717 head
= array
->queue
+ idx
;
1720 tmp
= list_entry(curr
, task_t
, run_list
);
1724 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1731 #ifdef CONFIG_SCHEDSTATS
1732 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1733 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1736 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1739 /* We only want to steal up to the prescribed number of tasks. */
1740 if (pulled
< max_nr_move
) {
1748 * Right now, this is the only place pull_task() is called,
1749 * so we can safely collect pull_task() stats here rather than
1750 * inside pull_task().
1752 schedstat_add(sd
, lb_gained
[idle
], pulled
);
1755 *all_pinned
= pinned
;
1760 * find_busiest_group finds and returns the busiest CPU group within the
1761 * domain. It calculates and returns the number of tasks which should be
1762 * moved to restore balance via the imbalance parameter.
1764 static struct sched_group
*
1765 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
1766 unsigned long *imbalance
, enum idle_type idle
)
1768 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1769 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
1771 max_load
= this_load
= total_load
= total_pwr
= 0;
1778 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1780 /* Tally up the load of all CPUs in the group */
1783 for_each_cpu_mask(i
, group
->cpumask
) {
1784 /* Bias balancing toward cpus of our domain */
1786 load
= target_load(i
);
1788 load
= source_load(i
);
1793 total_load
+= avg_load
;
1794 total_pwr
+= group
->cpu_power
;
1796 /* Adjust by relative CPU power of the group */
1797 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1800 this_load
= avg_load
;
1803 } else if (avg_load
> max_load
) {
1804 max_load
= avg_load
;
1808 group
= group
->next
;
1809 } while (group
!= sd
->groups
);
1811 if (!busiest
|| this_load
>= max_load
)
1814 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
1816 if (this_load
>= avg_load
||
1817 100*max_load
<= sd
->imbalance_pct
*this_load
)
1821 * We're trying to get all the cpus to the average_load, so we don't
1822 * want to push ourselves above the average load, nor do we wish to
1823 * reduce the max loaded cpu below the average load, as either of these
1824 * actions would just result in more rebalancing later, and ping-pong
1825 * tasks around. Thus we look for the minimum possible imbalance.
1826 * Negative imbalances (*we* are more loaded than anyone else) will
1827 * be counted as no imbalance for these purposes -- we can't fix that
1828 * by pulling tasks to us. Be careful of negative numbers as they'll
1829 * appear as very large values with unsigned longs.
1831 /* How much load to actually move to equalise the imbalance */
1832 *imbalance
= min((max_load
- avg_load
) * busiest
->cpu_power
,
1833 (avg_load
- this_load
) * this->cpu_power
)
1836 if (*imbalance
< SCHED_LOAD_SCALE
) {
1837 unsigned long pwr_now
= 0, pwr_move
= 0;
1840 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
1846 * OK, we don't have enough imbalance to justify moving tasks,
1847 * however we may be able to increase total CPU power used by
1851 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
1852 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
1853 pwr_now
/= SCHED_LOAD_SCALE
;
1855 /* Amount of load we'd subtract */
1856 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
1858 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
1861 /* Amount of load we'd add */
1862 if (max_load
*busiest
->cpu_power
<
1863 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
1864 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
1866 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
1867 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
1868 pwr_move
/= SCHED_LOAD_SCALE
;
1870 /* Move if we gain throughput */
1871 if (pwr_move
<= pwr_now
)
1878 /* Get rid of the scaling factor, rounding down as we divide */
1879 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
1884 if (busiest
&& (idle
== NEWLY_IDLE
||
1885 (idle
== SCHED_IDLE
&& max_load
> SCHED_LOAD_SCALE
)) ) {
1895 * find_busiest_queue - find the busiest runqueue among the cpus in group.
1897 static runqueue_t
*find_busiest_queue(struct sched_group
*group
)
1899 unsigned long load
, max_load
= 0;
1900 runqueue_t
*busiest
= NULL
;
1903 for_each_cpu_mask(i
, group
->cpumask
) {
1904 load
= source_load(i
);
1906 if (load
> max_load
) {
1908 busiest
= cpu_rq(i
);
1916 * Check this_cpu to ensure it is balanced within domain. Attempt to move
1917 * tasks if there is an imbalance.
1919 * Called with this_rq unlocked.
1921 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
1922 struct sched_domain
*sd
, enum idle_type idle
)
1924 struct sched_group
*group
;
1925 runqueue_t
*busiest
;
1926 unsigned long imbalance
;
1927 int nr_moved
, all_pinned
;
1928 int active_balance
= 0;
1930 spin_lock(&this_rq
->lock
);
1931 schedstat_inc(sd
, lb_cnt
[idle
]);
1933 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
);
1935 schedstat_inc(sd
, lb_nobusyg
[idle
]);
1939 busiest
= find_busiest_queue(group
);
1941 schedstat_inc(sd
, lb_nobusyq
[idle
]);
1946 * This should be "impossible", but since load
1947 * balancing is inherently racy and statistical,
1948 * it could happen in theory.
1950 if (unlikely(busiest
== this_rq
)) {
1955 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
1958 if (busiest
->nr_running
> 1) {
1960 * Attempt to move tasks. If find_busiest_group has found
1961 * an imbalance but busiest->nr_running <= 1, the group is
1962 * still unbalanced. nr_moved simply stays zero, so it is
1963 * correctly treated as an imbalance.
1965 double_lock_balance(this_rq
, busiest
);
1966 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
1967 imbalance
, sd
, idle
,
1969 spin_unlock(&busiest
->lock
);
1971 /* All tasks on this runqueue were pinned by CPU affinity */
1972 if (unlikely(all_pinned
))
1976 spin_unlock(&this_rq
->lock
);
1979 schedstat_inc(sd
, lb_failed
[idle
]);
1980 sd
->nr_balance_failed
++;
1982 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
1984 spin_lock(&busiest
->lock
);
1985 if (!busiest
->active_balance
) {
1986 busiest
->active_balance
= 1;
1987 busiest
->push_cpu
= this_cpu
;
1990 spin_unlock(&busiest
->lock
);
1992 wake_up_process(busiest
->migration_thread
);
1995 * We've kicked active balancing, reset the failure
1998 sd
->nr_balance_failed
= sd
->cache_nice_tries
;
2001 sd
->nr_balance_failed
= 0;
2003 if (likely(!active_balance
)) {
2004 /* We were unbalanced, so reset the balancing interval */
2005 sd
->balance_interval
= sd
->min_interval
;
2008 * If we've begun active balancing, start to back off. This
2009 * case may not be covered by the all_pinned logic if there
2010 * is only 1 task on the busy runqueue (because we don't call
2013 if (sd
->balance_interval
< sd
->max_interval
)
2014 sd
->balance_interval
*= 2;
2020 spin_unlock(&this_rq
->lock
);
2022 schedstat_inc(sd
, lb_balanced
[idle
]);
2024 sd
->nr_balance_failed
= 0;
2025 /* tune up the balancing interval */
2026 if (sd
->balance_interval
< sd
->max_interval
)
2027 sd
->balance_interval
*= 2;
2033 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2034 * tasks if there is an imbalance.
2036 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2037 * this_rq is locked.
2039 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2040 struct sched_domain
*sd
)
2042 struct sched_group
*group
;
2043 runqueue_t
*busiest
= NULL
;
2044 unsigned long imbalance
;
2047 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2048 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
);
2050 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2054 busiest
= find_busiest_queue(group
);
2055 if (!busiest
|| busiest
== this_rq
) {
2056 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2060 /* Attempt to move tasks */
2061 double_lock_balance(this_rq
, busiest
);
2063 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2064 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2065 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2067 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2069 sd
->nr_balance_failed
= 0;
2071 spin_unlock(&busiest
->lock
);
2075 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2076 sd
->nr_balance_failed
= 0;
2081 * idle_balance is called by schedule() if this_cpu is about to become
2082 * idle. Attempts to pull tasks from other CPUs.
2084 static inline void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2086 struct sched_domain
*sd
;
2088 for_each_domain(this_cpu
, sd
) {
2089 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2090 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2091 /* We've pulled tasks over so stop searching */
2099 * active_load_balance is run by migration threads. It pushes running tasks
2100 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2101 * running on each physical CPU where possible, and avoids physical /
2102 * logical imbalances.
2104 * Called with busiest_rq locked.
2106 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2108 struct sched_domain
*sd
;
2109 struct sched_group
*cpu_group
;
2110 runqueue_t
*target_rq
;
2111 cpumask_t visited_cpus
;
2115 * Search for suitable CPUs to push tasks to in successively higher
2116 * domains with SD_LOAD_BALANCE set.
2118 visited_cpus
= CPU_MASK_NONE
;
2119 for_each_domain(busiest_cpu
, sd
) {
2120 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2121 /* no more domains to search */
2124 schedstat_inc(sd
, alb_cnt
);
2126 cpu_group
= sd
->groups
;
2128 for_each_cpu_mask(cpu
, cpu_group
->cpumask
) {
2129 if (busiest_rq
->nr_running
<= 1)
2130 /* no more tasks left to move */
2132 if (cpu_isset(cpu
, visited_cpus
))
2134 cpu_set(cpu
, visited_cpus
);
2135 if (!cpu_and_siblings_are_idle(cpu
) || cpu
== busiest_cpu
)
2138 target_rq
= cpu_rq(cpu
);
2140 * This condition is "impossible", if it occurs
2141 * we need to fix it. Originally reported by
2142 * Bjorn Helgaas on a 128-cpu setup.
2144 BUG_ON(busiest_rq
== target_rq
);
2146 /* move a task from busiest_rq to target_rq */
2147 double_lock_balance(busiest_rq
, target_rq
);
2148 if (move_tasks(target_rq
, cpu
, busiest_rq
,
2149 1, sd
, SCHED_IDLE
, NULL
)) {
2150 schedstat_inc(sd
, alb_pushed
);
2152 schedstat_inc(sd
, alb_failed
);
2154 spin_unlock(&target_rq
->lock
);
2156 cpu_group
= cpu_group
->next
;
2157 } while (cpu_group
!= sd
->groups
);
2162 * rebalance_tick will get called every timer tick, on every CPU.
2164 * It checks each scheduling domain to see if it is due to be balanced,
2165 * and initiates a balancing operation if so.
2167 * Balancing parameters are set up in arch_init_sched_domains.
2170 /* Don't have all balancing operations going off at once */
2171 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2173 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2174 enum idle_type idle
)
2176 unsigned long old_load
, this_load
;
2177 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2178 struct sched_domain
*sd
;
2180 /* Update our load */
2181 old_load
= this_rq
->cpu_load
;
2182 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2184 * Round up the averaging division if load is increasing. This
2185 * prevents us from getting stuck on 9 if the load is 10, for
2188 if (this_load
> old_load
)
2190 this_rq
->cpu_load
= (old_load
+ this_load
) / 2;
2192 for_each_domain(this_cpu
, sd
) {
2193 unsigned long interval
;
2195 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2198 interval
= sd
->balance_interval
;
2199 if (idle
!= SCHED_IDLE
)
2200 interval
*= sd
->busy_factor
;
2202 /* scale ms to jiffies */
2203 interval
= msecs_to_jiffies(interval
);
2204 if (unlikely(!interval
))
2207 if (j
- sd
->last_balance
>= interval
) {
2208 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2209 /* We've pulled tasks over so no longer idle */
2212 sd
->last_balance
+= interval
;
2218 * on UP we do not need to balance between CPUs:
2220 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2223 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2228 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2231 #ifdef CONFIG_SCHED_SMT
2232 spin_lock(&rq
->lock
);
2234 * If an SMT sibling task has been put to sleep for priority
2235 * reasons reschedule the idle task to see if it can now run.
2237 if (rq
->nr_running
) {
2238 resched_task(rq
->idle
);
2241 spin_unlock(&rq
->lock
);
2246 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2248 EXPORT_PER_CPU_SYMBOL(kstat
);
2251 * This is called on clock ticks and on context switches.
2252 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2254 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2255 unsigned long long now
)
2257 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2258 p
->sched_time
+= now
- last
;
2262 * Return current->sched_time plus any more ns on the sched_clock
2263 * that have not yet been banked.
2265 unsigned long long current_sched_time(const task_t
*tsk
)
2267 unsigned long long ns
;
2268 unsigned long flags
;
2269 local_irq_save(flags
);
2270 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2271 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2272 local_irq_restore(flags
);
2277 * We place interactive tasks back into the active array, if possible.
2279 * To guarantee that this does not starve expired tasks we ignore the
2280 * interactivity of a task if the first expired task had to wait more
2281 * than a 'reasonable' amount of time. This deadline timeout is
2282 * load-dependent, as the frequency of array switched decreases with
2283 * increasing number of running tasks. We also ignore the interactivity
2284 * if a better static_prio task has expired:
2286 #define EXPIRED_STARVING(rq) \
2287 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2288 (jiffies - (rq)->expired_timestamp >= \
2289 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2290 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2293 * Account user cpu time to a process.
2294 * @p: the process that the cpu time gets accounted to
2295 * @hardirq_offset: the offset to subtract from hardirq_count()
2296 * @cputime: the cpu time spent in user space since the last update
2298 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2300 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2303 p
->utime
= cputime_add(p
->utime
, cputime
);
2305 /* Add user time to cpustat. */
2306 tmp
= cputime_to_cputime64(cputime
);
2307 if (TASK_NICE(p
) > 0)
2308 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2310 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2314 * Account system cpu time to a process.
2315 * @p: the process that the cpu time gets accounted to
2316 * @hardirq_offset: the offset to subtract from hardirq_count()
2317 * @cputime: the cpu time spent in kernel space since the last update
2319 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2322 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2323 runqueue_t
*rq
= this_rq();
2326 p
->stime
= cputime_add(p
->stime
, cputime
);
2328 /* Add system time to cpustat. */
2329 tmp
= cputime_to_cputime64(cputime
);
2330 if (hardirq_count() - hardirq_offset
)
2331 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2332 else if (softirq_count())
2333 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2334 else if (p
!= rq
->idle
)
2335 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2336 else if (atomic_read(&rq
->nr_iowait
) > 0)
2337 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2339 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2340 /* Account for system time used */
2341 acct_update_integrals(p
);
2342 /* Update rss highwater mark */
2343 update_mem_hiwater(p
);
2347 * Account for involuntary wait time.
2348 * @p: the process from which the cpu time has been stolen
2349 * @steal: the cpu time spent in involuntary wait
2351 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2353 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2354 cputime64_t tmp
= cputime_to_cputime64(steal
);
2355 runqueue_t
*rq
= this_rq();
2357 if (p
== rq
->idle
) {
2358 p
->stime
= cputime_add(p
->stime
, steal
);
2359 if (atomic_read(&rq
->nr_iowait
) > 0)
2360 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2362 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2364 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2368 * This function gets called by the timer code, with HZ frequency.
2369 * We call it with interrupts disabled.
2371 * It also gets called by the fork code, when changing the parent's
2374 void scheduler_tick(void)
2376 int cpu
= smp_processor_id();
2377 runqueue_t
*rq
= this_rq();
2378 task_t
*p
= current
;
2379 unsigned long long now
= sched_clock();
2381 update_cpu_clock(p
, rq
, now
);
2383 rq
->timestamp_last_tick
= now
;
2385 if (p
== rq
->idle
) {
2386 if (wake_priority_sleeper(rq
))
2388 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2392 /* Task might have expired already, but not scheduled off yet */
2393 if (p
->array
!= rq
->active
) {
2394 set_tsk_need_resched(p
);
2397 spin_lock(&rq
->lock
);
2399 * The task was running during this tick - update the
2400 * time slice counter. Note: we do not update a thread's
2401 * priority until it either goes to sleep or uses up its
2402 * timeslice. This makes it possible for interactive tasks
2403 * to use up their timeslices at their highest priority levels.
2407 * RR tasks need a special form of timeslice management.
2408 * FIFO tasks have no timeslices.
2410 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2411 p
->time_slice
= task_timeslice(p
);
2412 p
->first_time_slice
= 0;
2413 set_tsk_need_resched(p
);
2415 /* put it at the end of the queue: */
2416 requeue_task(p
, rq
->active
);
2420 if (!--p
->time_slice
) {
2421 dequeue_task(p
, rq
->active
);
2422 set_tsk_need_resched(p
);
2423 p
->prio
= effective_prio(p
);
2424 p
->time_slice
= task_timeslice(p
);
2425 p
->first_time_slice
= 0;
2427 if (!rq
->expired_timestamp
)
2428 rq
->expired_timestamp
= jiffies
;
2429 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2430 enqueue_task(p
, rq
->expired
);
2431 if (p
->static_prio
< rq
->best_expired_prio
)
2432 rq
->best_expired_prio
= p
->static_prio
;
2434 enqueue_task(p
, rq
->active
);
2437 * Prevent a too long timeslice allowing a task to monopolize
2438 * the CPU. We do this by splitting up the timeslice into
2441 * Note: this does not mean the task's timeslices expire or
2442 * get lost in any way, they just might be preempted by
2443 * another task of equal priority. (one with higher
2444 * priority would have preempted this task already.) We
2445 * requeue this task to the end of the list on this priority
2446 * level, which is in essence a round-robin of tasks with
2449 * This only applies to tasks in the interactive
2450 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2452 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2453 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2454 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2455 (p
->array
== rq
->active
)) {
2457 requeue_task(p
, rq
->active
);
2458 set_tsk_need_resched(p
);
2462 spin_unlock(&rq
->lock
);
2464 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2467 #ifdef CONFIG_SCHED_SMT
2468 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2470 struct sched_domain
*sd
= this_rq
->sd
;
2471 cpumask_t sibling_map
;
2474 if (!(sd
->flags
& SD_SHARE_CPUPOWER
))
2478 * Unlock the current runqueue because we have to lock in
2479 * CPU order to avoid deadlocks. Caller knows that we might
2480 * unlock. We keep IRQs disabled.
2482 spin_unlock(&this_rq
->lock
);
2484 sibling_map
= sd
->span
;
2486 for_each_cpu_mask(i
, sibling_map
)
2487 spin_lock(&cpu_rq(i
)->lock
);
2489 * We clear this CPU from the mask. This both simplifies the
2490 * inner loop and keps this_rq locked when we exit:
2492 cpu_clear(this_cpu
, sibling_map
);
2494 for_each_cpu_mask(i
, sibling_map
) {
2495 runqueue_t
*smt_rq
= cpu_rq(i
);
2498 * If an SMT sibling task is sleeping due to priority
2499 * reasons wake it up now.
2501 if (smt_rq
->curr
== smt_rq
->idle
&& smt_rq
->nr_running
)
2502 resched_task(smt_rq
->idle
);
2505 for_each_cpu_mask(i
, sibling_map
)
2506 spin_unlock(&cpu_rq(i
)->lock
);
2508 * We exit with this_cpu's rq still held and IRQs
2513 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2515 struct sched_domain
*sd
= this_rq
->sd
;
2516 cpumask_t sibling_map
;
2517 prio_array_t
*array
;
2521 if (!(sd
->flags
& SD_SHARE_CPUPOWER
))
2525 * The same locking rules and details apply as for
2526 * wake_sleeping_dependent():
2528 spin_unlock(&this_rq
->lock
);
2529 sibling_map
= sd
->span
;
2530 for_each_cpu_mask(i
, sibling_map
)
2531 spin_lock(&cpu_rq(i
)->lock
);
2532 cpu_clear(this_cpu
, sibling_map
);
2535 * Establish next task to be run - it might have gone away because
2536 * we released the runqueue lock above:
2538 if (!this_rq
->nr_running
)
2540 array
= this_rq
->active
;
2541 if (!array
->nr_active
)
2542 array
= this_rq
->expired
;
2543 BUG_ON(!array
->nr_active
);
2545 p
= list_entry(array
->queue
[sched_find_first_bit(array
->bitmap
)].next
,
2548 for_each_cpu_mask(i
, sibling_map
) {
2549 runqueue_t
*smt_rq
= cpu_rq(i
);
2550 task_t
*smt_curr
= smt_rq
->curr
;
2553 * If a user task with lower static priority than the
2554 * running task on the SMT sibling is trying to schedule,
2555 * delay it till there is proportionately less timeslice
2556 * left of the sibling task to prevent a lower priority
2557 * task from using an unfair proportion of the
2558 * physical cpu's resources. -ck
2560 if (((smt_curr
->time_slice
* (100 - sd
->per_cpu_gain
) / 100) >
2561 task_timeslice(p
) || rt_task(smt_curr
)) &&
2562 p
->mm
&& smt_curr
->mm
&& !rt_task(p
))
2566 * Reschedule a lower priority task on the SMT sibling,
2567 * or wake it up if it has been put to sleep for priority
2570 if ((((p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100) >
2571 task_timeslice(smt_curr
) || rt_task(p
)) &&
2572 smt_curr
->mm
&& p
->mm
&& !rt_task(smt_curr
)) ||
2573 (smt_curr
== smt_rq
->idle
&& smt_rq
->nr_running
))
2574 resched_task(smt_curr
);
2577 for_each_cpu_mask(i
, sibling_map
)
2578 spin_unlock(&cpu_rq(i
)->lock
);
2582 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2586 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2592 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2594 void fastcall
add_preempt_count(int val
)
2599 BUG_ON((preempt_count() < 0));
2600 preempt_count() += val
;
2602 * Spinlock count overflowing soon?
2604 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2606 EXPORT_SYMBOL(add_preempt_count
);
2608 void fastcall
sub_preempt_count(int val
)
2613 BUG_ON(val
> preempt_count());
2615 * Is the spinlock portion underflowing?
2617 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2618 preempt_count() -= val
;
2620 EXPORT_SYMBOL(sub_preempt_count
);
2625 * schedule() is the main scheduler function.
2627 asmlinkage
void __sched
schedule(void)
2630 task_t
*prev
, *next
;
2632 prio_array_t
*array
;
2633 struct list_head
*queue
;
2634 unsigned long long now
;
2635 unsigned long run_time
;
2639 * Test if we are atomic. Since do_exit() needs to call into
2640 * schedule() atomically, we ignore that path for now.
2641 * Otherwise, whine if we are scheduling when we should not be.
2643 if (likely(!current
->exit_state
)) {
2644 if (unlikely(in_atomic())) {
2645 printk(KERN_ERR
"scheduling while atomic: "
2647 current
->comm
, preempt_count(), current
->pid
);
2651 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2656 release_kernel_lock(prev
);
2657 need_resched_nonpreemptible
:
2661 * The idle thread is not allowed to schedule!
2662 * Remove this check after it has been exercised a bit.
2664 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2665 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
2669 schedstat_inc(rq
, sched_cnt
);
2670 now
= sched_clock();
2671 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
2672 run_time
= now
- prev
->timestamp
;
2673 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
2676 run_time
= NS_MAX_SLEEP_AVG
;
2679 * Tasks charged proportionately less run_time at high sleep_avg to
2680 * delay them losing their interactive status
2682 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
2684 spin_lock_irq(&rq
->lock
);
2686 if (unlikely(prev
->flags
& PF_DEAD
))
2687 prev
->state
= EXIT_DEAD
;
2689 switch_count
= &prev
->nivcsw
;
2690 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2691 switch_count
= &prev
->nvcsw
;
2692 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
2693 unlikely(signal_pending(prev
))))
2694 prev
->state
= TASK_RUNNING
;
2696 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
2697 rq
->nr_uninterruptible
++;
2698 deactivate_task(prev
, rq
);
2702 cpu
= smp_processor_id();
2703 if (unlikely(!rq
->nr_running
)) {
2705 idle_balance(cpu
, rq
);
2706 if (!rq
->nr_running
) {
2708 rq
->expired_timestamp
= 0;
2709 wake_sleeping_dependent(cpu
, rq
);
2711 * wake_sleeping_dependent() might have released
2712 * the runqueue, so break out if we got new
2715 if (!rq
->nr_running
)
2719 if (dependent_sleeper(cpu
, rq
)) {
2724 * dependent_sleeper() releases and reacquires the runqueue
2725 * lock, hence go into the idle loop if the rq went
2728 if (unlikely(!rq
->nr_running
))
2733 if (unlikely(!array
->nr_active
)) {
2735 * Switch the active and expired arrays.
2737 schedstat_inc(rq
, sched_switch
);
2738 rq
->active
= rq
->expired
;
2739 rq
->expired
= array
;
2741 rq
->expired_timestamp
= 0;
2742 rq
->best_expired_prio
= MAX_PRIO
;
2745 idx
= sched_find_first_bit(array
->bitmap
);
2746 queue
= array
->queue
+ idx
;
2747 next
= list_entry(queue
->next
, task_t
, run_list
);
2749 if (!rt_task(next
) && next
->activated
> 0) {
2750 unsigned long long delta
= now
- next
->timestamp
;
2751 if (unlikely((long long)(now
- next
->timestamp
) < 0))
2754 if (next
->activated
== 1)
2755 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
2757 array
= next
->array
;
2758 dequeue_task(next
, array
);
2759 recalc_task_prio(next
, next
->timestamp
+ delta
);
2760 enqueue_task(next
, array
);
2762 next
->activated
= 0;
2764 if (next
== rq
->idle
)
2765 schedstat_inc(rq
, sched_goidle
);
2767 clear_tsk_need_resched(prev
);
2768 rcu_qsctr_inc(task_cpu(prev
));
2770 update_cpu_clock(prev
, rq
, now
);
2772 prev
->sleep_avg
-= run_time
;
2773 if ((long)prev
->sleep_avg
<= 0)
2774 prev
->sleep_avg
= 0;
2775 prev
->timestamp
= prev
->last_ran
= now
;
2777 sched_info_switch(prev
, next
);
2778 if (likely(prev
!= next
)) {
2779 next
->timestamp
= now
;
2784 prepare_arch_switch(rq
, next
);
2785 prev
= context_switch(rq
, prev
, next
);
2788 finish_task_switch(prev
);
2790 spin_unlock_irq(&rq
->lock
);
2793 if (unlikely(reacquire_kernel_lock(prev
) < 0))
2794 goto need_resched_nonpreemptible
;
2795 preempt_enable_no_resched();
2796 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
2800 EXPORT_SYMBOL(schedule
);
2802 #ifdef CONFIG_PREEMPT
2804 * this is is the entry point to schedule() from in-kernel preemption
2805 * off of preempt_enable. Kernel preemptions off return from interrupt
2806 * occur there and call schedule directly.
2808 asmlinkage
void __sched
preempt_schedule(void)
2810 struct thread_info
*ti
= current_thread_info();
2811 #ifdef CONFIG_PREEMPT_BKL
2812 struct task_struct
*task
= current
;
2813 int saved_lock_depth
;
2816 * If there is a non-zero preempt_count or interrupts are disabled,
2817 * we do not want to preempt the current task. Just return..
2819 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
2823 add_preempt_count(PREEMPT_ACTIVE
);
2825 * We keep the big kernel semaphore locked, but we
2826 * clear ->lock_depth so that schedule() doesnt
2827 * auto-release the semaphore:
2829 #ifdef CONFIG_PREEMPT_BKL
2830 saved_lock_depth
= task
->lock_depth
;
2831 task
->lock_depth
= -1;
2834 #ifdef CONFIG_PREEMPT_BKL
2835 task
->lock_depth
= saved_lock_depth
;
2837 sub_preempt_count(PREEMPT_ACTIVE
);
2839 /* we could miss a preemption opportunity between schedule and now */
2841 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
2845 EXPORT_SYMBOL(preempt_schedule
);
2848 * this is is the entry point to schedule() from kernel preemption
2849 * off of irq context.
2850 * Note, that this is called and return with irqs disabled. This will
2851 * protect us against recursive calling from irq.
2853 asmlinkage
void __sched
preempt_schedule_irq(void)
2855 struct thread_info
*ti
= current_thread_info();
2856 #ifdef CONFIG_PREEMPT_BKL
2857 struct task_struct
*task
= current
;
2858 int saved_lock_depth
;
2860 /* Catch callers which need to be fixed*/
2861 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
2864 add_preempt_count(PREEMPT_ACTIVE
);
2866 * We keep the big kernel semaphore locked, but we
2867 * clear ->lock_depth so that schedule() doesnt
2868 * auto-release the semaphore:
2870 #ifdef CONFIG_PREEMPT_BKL
2871 saved_lock_depth
= task
->lock_depth
;
2872 task
->lock_depth
= -1;
2876 local_irq_disable();
2877 #ifdef CONFIG_PREEMPT_BKL
2878 task
->lock_depth
= saved_lock_depth
;
2880 sub_preempt_count(PREEMPT_ACTIVE
);
2882 /* we could miss a preemption opportunity between schedule and now */
2884 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
2888 #endif /* CONFIG_PREEMPT */
2890 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
, void *key
)
2892 task_t
*p
= curr
->private;
2893 return try_to_wake_up(p
, mode
, sync
);
2896 EXPORT_SYMBOL(default_wake_function
);
2899 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
2900 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
2901 * number) then we wake all the non-exclusive tasks and one exclusive task.
2903 * There are circumstances in which we can try to wake a task which has already
2904 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
2905 * zero in this (rare) case, and we handle it by continuing to scan the queue.
2907 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
2908 int nr_exclusive
, int sync
, void *key
)
2910 struct list_head
*tmp
, *next
;
2912 list_for_each_safe(tmp
, next
, &q
->task_list
) {
2915 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
2916 flags
= curr
->flags
;
2917 if (curr
->func(curr
, mode
, sync
, key
) &&
2918 (flags
& WQ_FLAG_EXCLUSIVE
) &&
2925 * __wake_up - wake up threads blocked on a waitqueue.
2927 * @mode: which threads
2928 * @nr_exclusive: how many wake-one or wake-many threads to wake up
2929 * @key: is directly passed to the wakeup function
2931 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
2932 int nr_exclusive
, void *key
)
2934 unsigned long flags
;
2936 spin_lock_irqsave(&q
->lock
, flags
);
2937 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
2938 spin_unlock_irqrestore(&q
->lock
, flags
);
2941 EXPORT_SYMBOL(__wake_up
);
2944 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
2946 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
2948 __wake_up_common(q
, mode
, 1, 0, NULL
);
2952 * __wake_up_sync - wake up threads blocked on a waitqueue.
2954 * @mode: which threads
2955 * @nr_exclusive: how many wake-one or wake-many threads to wake up
2957 * The sync wakeup differs that the waker knows that it will schedule
2958 * away soon, so while the target thread will be woken up, it will not
2959 * be migrated to another CPU - ie. the two threads are 'synchronized'
2960 * with each other. This can prevent needless bouncing between CPUs.
2962 * On UP it can prevent extra preemption.
2964 void fastcall
__wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
2966 unsigned long flags
;
2972 if (unlikely(!nr_exclusive
))
2975 spin_lock_irqsave(&q
->lock
, flags
);
2976 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
2977 spin_unlock_irqrestore(&q
->lock
, flags
);
2979 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
2981 void fastcall
complete(struct completion
*x
)
2983 unsigned long flags
;
2985 spin_lock_irqsave(&x
->wait
.lock
, flags
);
2987 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
2989 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
2991 EXPORT_SYMBOL(complete
);
2993 void fastcall
complete_all(struct completion
*x
)
2995 unsigned long flags
;
2997 spin_lock_irqsave(&x
->wait
.lock
, flags
);
2998 x
->done
+= UINT_MAX
/2;
2999 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3001 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3003 EXPORT_SYMBOL(complete_all
);
3005 void fastcall __sched
wait_for_completion(struct completion
*x
)
3008 spin_lock_irq(&x
->wait
.lock
);
3010 DECLARE_WAITQUEUE(wait
, current
);
3012 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3013 __add_wait_queue_tail(&x
->wait
, &wait
);
3015 __set_current_state(TASK_UNINTERRUPTIBLE
);
3016 spin_unlock_irq(&x
->wait
.lock
);
3018 spin_lock_irq(&x
->wait
.lock
);
3020 __remove_wait_queue(&x
->wait
, &wait
);
3023 spin_unlock_irq(&x
->wait
.lock
);
3025 EXPORT_SYMBOL(wait_for_completion
);
3027 unsigned long fastcall __sched
3028 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3032 spin_lock_irq(&x
->wait
.lock
);
3034 DECLARE_WAITQUEUE(wait
, current
);
3036 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3037 __add_wait_queue_tail(&x
->wait
, &wait
);
3039 __set_current_state(TASK_UNINTERRUPTIBLE
);
3040 spin_unlock_irq(&x
->wait
.lock
);
3041 timeout
= schedule_timeout(timeout
);
3042 spin_lock_irq(&x
->wait
.lock
);
3044 __remove_wait_queue(&x
->wait
, &wait
);
3048 __remove_wait_queue(&x
->wait
, &wait
);
3052 spin_unlock_irq(&x
->wait
.lock
);
3055 EXPORT_SYMBOL(wait_for_completion_timeout
);
3057 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3063 spin_lock_irq(&x
->wait
.lock
);
3065 DECLARE_WAITQUEUE(wait
, current
);
3067 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3068 __add_wait_queue_tail(&x
->wait
, &wait
);
3070 if (signal_pending(current
)) {
3072 __remove_wait_queue(&x
->wait
, &wait
);
3075 __set_current_state(TASK_INTERRUPTIBLE
);
3076 spin_unlock_irq(&x
->wait
.lock
);
3078 spin_lock_irq(&x
->wait
.lock
);
3080 __remove_wait_queue(&x
->wait
, &wait
);
3084 spin_unlock_irq(&x
->wait
.lock
);
3088 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3090 unsigned long fastcall __sched
3091 wait_for_completion_interruptible_timeout(struct completion
*x
,
3092 unsigned long timeout
)
3096 spin_lock_irq(&x
->wait
.lock
);
3098 DECLARE_WAITQUEUE(wait
, current
);
3100 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3101 __add_wait_queue_tail(&x
->wait
, &wait
);
3103 if (signal_pending(current
)) {
3104 timeout
= -ERESTARTSYS
;
3105 __remove_wait_queue(&x
->wait
, &wait
);
3108 __set_current_state(TASK_INTERRUPTIBLE
);
3109 spin_unlock_irq(&x
->wait
.lock
);
3110 timeout
= schedule_timeout(timeout
);
3111 spin_lock_irq(&x
->wait
.lock
);
3113 __remove_wait_queue(&x
->wait
, &wait
);
3117 __remove_wait_queue(&x
->wait
, &wait
);
3121 spin_unlock_irq(&x
->wait
.lock
);
3124 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3127 #define SLEEP_ON_VAR \
3128 unsigned long flags; \
3129 wait_queue_t wait; \
3130 init_waitqueue_entry(&wait, current);
3132 #define SLEEP_ON_HEAD \
3133 spin_lock_irqsave(&q->lock,flags); \
3134 __add_wait_queue(q, &wait); \
3135 spin_unlock(&q->lock);
3137 #define SLEEP_ON_TAIL \
3138 spin_lock_irq(&q->lock); \
3139 __remove_wait_queue(q, &wait); \
3140 spin_unlock_irqrestore(&q->lock, flags);
3142 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3146 current
->state
= TASK_INTERRUPTIBLE
;
3153 EXPORT_SYMBOL(interruptible_sleep_on
);
3155 long fastcall __sched
interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3159 current
->state
= TASK_INTERRUPTIBLE
;
3162 timeout
= schedule_timeout(timeout
);
3168 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3170 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3174 current
->state
= TASK_UNINTERRUPTIBLE
;
3181 EXPORT_SYMBOL(sleep_on
);
3183 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3187 current
->state
= TASK_UNINTERRUPTIBLE
;
3190 timeout
= schedule_timeout(timeout
);
3196 EXPORT_SYMBOL(sleep_on_timeout
);
3198 void set_user_nice(task_t
*p
, long nice
)
3200 unsigned long flags
;
3201 prio_array_t
*array
;
3203 int old_prio
, new_prio
, delta
;
3205 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3208 * We have to be careful, if called from sys_setpriority(),
3209 * the task might be in the middle of scheduling on another CPU.
3211 rq
= task_rq_lock(p
, &flags
);
3213 * The RT priorities are set via sched_setscheduler(), but we still
3214 * allow the 'normal' nice value to be set - but as expected
3215 * it wont have any effect on scheduling until the task is
3219 p
->static_prio
= NICE_TO_PRIO(nice
);
3224 dequeue_task(p
, array
);
3227 new_prio
= NICE_TO_PRIO(nice
);
3228 delta
= new_prio
- old_prio
;
3229 p
->static_prio
= NICE_TO_PRIO(nice
);
3233 enqueue_task(p
, array
);
3235 * If the task increased its priority or is running and
3236 * lowered its priority, then reschedule its CPU:
3238 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3239 resched_task(rq
->curr
);
3242 task_rq_unlock(rq
, &flags
);
3245 EXPORT_SYMBOL(set_user_nice
);
3248 * can_nice - check if a task can reduce its nice value
3252 int can_nice(const task_t
*p
, const int nice
)
3254 /* convert nice value [19,-20] to rlimit style value [0,39] */
3255 int nice_rlim
= 19 - nice
;
3256 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3257 capable(CAP_SYS_NICE
));
3260 #ifdef __ARCH_WANT_SYS_NICE
3263 * sys_nice - change the priority of the current process.
3264 * @increment: priority increment
3266 * sys_setpriority is a more generic, but much slower function that
3267 * does similar things.
3269 asmlinkage
long sys_nice(int increment
)
3275 * Setpriority might change our priority at the same moment.
3276 * We don't have to worry. Conceptually one call occurs first
3277 * and we have a single winner.
3279 if (increment
< -40)
3284 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3290 if (increment
< 0 && !can_nice(current
, nice
))
3293 retval
= security_task_setnice(current
, nice
);
3297 set_user_nice(current
, nice
);
3304 * task_prio - return the priority value of a given task.
3305 * @p: the task in question.
3307 * This is the priority value as seen by users in /proc.
3308 * RT tasks are offset by -200. Normal tasks are centered
3309 * around 0, value goes from -16 to +15.
3311 int task_prio(const task_t
*p
)
3313 return p
->prio
- MAX_RT_PRIO
;
3317 * task_nice - return the nice value of a given task.
3318 * @p: the task in question.
3320 int task_nice(const task_t
*p
)
3322 return TASK_NICE(p
);
3326 * The only users of task_nice are binfmt_elf and binfmt_elf32.
3327 * binfmt_elf is no longer modular, but binfmt_elf32 still is.
3328 * Therefore, task_nice is needed if there is a compat_mode.
3330 #ifdef CONFIG_COMPAT
3331 EXPORT_SYMBOL_GPL(task_nice
);
3335 * idle_cpu - is a given cpu idle currently?
3336 * @cpu: the processor in question.
3338 int idle_cpu(int cpu
)
3340 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3343 EXPORT_SYMBOL_GPL(idle_cpu
);
3346 * idle_task - return the idle task for a given cpu.
3347 * @cpu: the processor in question.
3349 task_t
*idle_task(int cpu
)
3351 return cpu_rq(cpu
)->idle
;
3355 * find_process_by_pid - find a process with a matching PID value.
3356 * @pid: the pid in question.
3358 static inline task_t
*find_process_by_pid(pid_t pid
)
3360 return pid
? find_task_by_pid(pid
) : current
;
3363 /* Actually do priority change: must hold rq lock. */
3364 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3368 p
->rt_priority
= prio
;
3369 if (policy
!= SCHED_NORMAL
)
3370 p
->prio
= MAX_USER_RT_PRIO
-1 - p
->rt_priority
;
3372 p
->prio
= p
->static_prio
;
3376 * sched_setscheduler - change the scheduling policy and/or RT priority of
3378 * @p: the task in question.
3379 * @policy: new policy.
3380 * @param: structure containing the new RT priority.
3382 int sched_setscheduler(struct task_struct
*p
, int policy
, struct sched_param
*param
)
3385 int oldprio
, oldpolicy
= -1;
3386 prio_array_t
*array
;
3387 unsigned long flags
;
3391 /* double check policy once rq lock held */
3393 policy
= oldpolicy
= p
->policy
;
3394 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3395 policy
!= SCHED_NORMAL
)
3398 * Valid priorities for SCHED_FIFO and SCHED_RR are
3399 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3401 if (param
->sched_priority
< 0 ||
3402 param
->sched_priority
> MAX_USER_RT_PRIO
-1)
3404 if ((policy
== SCHED_NORMAL
) != (param
->sched_priority
== 0))
3407 if ((policy
== SCHED_FIFO
|| policy
== SCHED_RR
) &&
3408 param
->sched_priority
> p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
&&
3409 !capable(CAP_SYS_NICE
))
3411 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3412 !capable(CAP_SYS_NICE
))
3415 retval
= security_task_setscheduler(p
, policy
, param
);
3419 * To be able to change p->policy safely, the apropriate
3420 * runqueue lock must be held.
3422 rq
= task_rq_lock(p
, &flags
);
3423 /* recheck policy now with rq lock held */
3424 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3425 policy
= oldpolicy
= -1;
3426 task_rq_unlock(rq
, &flags
);
3431 deactivate_task(p
, rq
);
3433 __setscheduler(p
, policy
, param
->sched_priority
);
3435 __activate_task(p
, rq
);
3437 * Reschedule if we are currently running on this runqueue and
3438 * our priority decreased, or if we are not currently running on
3439 * this runqueue and our priority is higher than the current's
3441 if (task_running(rq
, p
)) {
3442 if (p
->prio
> oldprio
)
3443 resched_task(rq
->curr
);
3444 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3445 resched_task(rq
->curr
);
3447 task_rq_unlock(rq
, &flags
);
3450 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3452 static int do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3455 struct sched_param lparam
;
3456 struct task_struct
*p
;
3458 if (!param
|| pid
< 0)
3460 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3462 read_lock_irq(&tasklist_lock
);
3463 p
= find_process_by_pid(pid
);
3465 read_unlock_irq(&tasklist_lock
);
3468 retval
= sched_setscheduler(p
, policy
, &lparam
);
3469 read_unlock_irq(&tasklist_lock
);
3474 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3475 * @pid: the pid in question.
3476 * @policy: new policy.
3477 * @param: structure containing the new RT priority.
3479 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3480 struct sched_param __user
*param
)
3482 return do_sched_setscheduler(pid
, policy
, param
);
3486 * sys_sched_setparam - set/change the RT priority of a thread
3487 * @pid: the pid in question.
3488 * @param: structure containing the new RT priority.
3490 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3492 return do_sched_setscheduler(pid
, -1, param
);
3496 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3497 * @pid: the pid in question.
3499 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3501 int retval
= -EINVAL
;
3508 read_lock(&tasklist_lock
);
3509 p
= find_process_by_pid(pid
);
3511 retval
= security_task_getscheduler(p
);
3515 read_unlock(&tasklist_lock
);
3522 * sys_sched_getscheduler - get the RT priority of a thread
3523 * @pid: the pid in question.
3524 * @param: structure containing the RT priority.
3526 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3528 struct sched_param lp
;
3529 int retval
= -EINVAL
;
3532 if (!param
|| pid
< 0)
3535 read_lock(&tasklist_lock
);
3536 p
= find_process_by_pid(pid
);
3541 retval
= security_task_getscheduler(p
);
3545 lp
.sched_priority
= p
->rt_priority
;
3546 read_unlock(&tasklist_lock
);
3549 * This one might sleep, we cannot do it with a spinlock held ...
3551 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3557 read_unlock(&tasklist_lock
);
3561 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3565 cpumask_t cpus_allowed
;
3568 read_lock(&tasklist_lock
);
3570 p
= find_process_by_pid(pid
);
3572 read_unlock(&tasklist_lock
);
3573 unlock_cpu_hotplug();
3578 * It is not safe to call set_cpus_allowed with the
3579 * tasklist_lock held. We will bump the task_struct's
3580 * usage count and then drop tasklist_lock.
3583 read_unlock(&tasklist_lock
);
3586 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3587 !capable(CAP_SYS_NICE
))
3590 cpus_allowed
= cpuset_cpus_allowed(p
);
3591 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3592 retval
= set_cpus_allowed(p
, new_mask
);
3596 unlock_cpu_hotplug();
3600 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3601 cpumask_t
*new_mask
)
3603 if (len
< sizeof(cpumask_t
)) {
3604 memset(new_mask
, 0, sizeof(cpumask_t
));
3605 } else if (len
> sizeof(cpumask_t
)) {
3606 len
= sizeof(cpumask_t
);
3608 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3612 * sys_sched_setaffinity - set the cpu affinity of a process
3613 * @pid: pid of the process
3614 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3615 * @user_mask_ptr: user-space pointer to the new cpu mask
3617 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3618 unsigned long __user
*user_mask_ptr
)
3623 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3627 return sched_setaffinity(pid
, new_mask
);
3631 * Represents all cpu's present in the system
3632 * In systems capable of hotplug, this map could dynamically grow
3633 * as new cpu's are detected in the system via any platform specific
3634 * method, such as ACPI for e.g.
3637 cpumask_t cpu_present_map
;
3638 EXPORT_SYMBOL(cpu_present_map
);
3641 cpumask_t cpu_online_map
= CPU_MASK_ALL
;
3642 cpumask_t cpu_possible_map
= CPU_MASK_ALL
;
3645 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
3651 read_lock(&tasklist_lock
);
3654 p
= find_process_by_pid(pid
);
3659 cpus_and(*mask
, p
->cpus_allowed
, cpu_possible_map
);
3662 read_unlock(&tasklist_lock
);
3663 unlock_cpu_hotplug();
3671 * sys_sched_getaffinity - get the cpu affinity of a process
3672 * @pid: pid of the process
3673 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3674 * @user_mask_ptr: user-space pointer to hold the current cpu mask
3676 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
3677 unsigned long __user
*user_mask_ptr
)
3682 if (len
< sizeof(cpumask_t
))
3685 ret
= sched_getaffinity(pid
, &mask
);
3689 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
3692 return sizeof(cpumask_t
);
3696 * sys_sched_yield - yield the current processor to other threads.
3698 * this function yields the current CPU by moving the calling thread
3699 * to the expired array. If there are no other threads running on this
3700 * CPU then this function will return.
3702 asmlinkage
long sys_sched_yield(void)
3704 runqueue_t
*rq
= this_rq_lock();
3705 prio_array_t
*array
= current
->array
;
3706 prio_array_t
*target
= rq
->expired
;
3708 schedstat_inc(rq
, yld_cnt
);
3710 * We implement yielding by moving the task into the expired
3713 * (special rule: RT tasks will just roundrobin in the active
3716 if (rt_task(current
))
3717 target
= rq
->active
;
3719 if (current
->array
->nr_active
== 1) {
3720 schedstat_inc(rq
, yld_act_empty
);
3721 if (!rq
->expired
->nr_active
)
3722 schedstat_inc(rq
, yld_both_empty
);
3723 } else if (!rq
->expired
->nr_active
)
3724 schedstat_inc(rq
, yld_exp_empty
);
3726 if (array
!= target
) {
3727 dequeue_task(current
, array
);
3728 enqueue_task(current
, target
);
3731 * requeue_task is cheaper so perform that if possible.
3733 requeue_task(current
, array
);
3736 * Since we are going to call schedule() anyway, there's
3737 * no need to preempt or enable interrupts:
3739 __release(rq
->lock
);
3740 _raw_spin_unlock(&rq
->lock
);
3741 preempt_enable_no_resched();
3748 static inline void __cond_resched(void)
3751 add_preempt_count(PREEMPT_ACTIVE
);
3753 sub_preempt_count(PREEMPT_ACTIVE
);
3754 } while (need_resched());
3757 int __sched
cond_resched(void)
3759 if (need_resched()) {
3766 EXPORT_SYMBOL(cond_resched
);
3769 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
3770 * call schedule, and on return reacquire the lock.
3772 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
3773 * operations here to prevent schedule() from being called twice (once via
3774 * spin_unlock(), once by hand).
3776 int cond_resched_lock(spinlock_t
* lock
)
3780 if (need_lockbreak(lock
)) {
3786 if (need_resched()) {
3787 _raw_spin_unlock(lock
);
3788 preempt_enable_no_resched();
3796 EXPORT_SYMBOL(cond_resched_lock
);
3798 int __sched
cond_resched_softirq(void)
3800 BUG_ON(!in_softirq());
3802 if (need_resched()) {
3803 __local_bh_enable();
3811 EXPORT_SYMBOL(cond_resched_softirq
);
3815 * yield - yield the current processor to other threads.
3817 * this is a shortcut for kernel-space yielding - it marks the
3818 * thread runnable and calls sys_sched_yield().
3820 void __sched
yield(void)
3822 set_current_state(TASK_RUNNING
);
3826 EXPORT_SYMBOL(yield
);
3829 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3830 * that process accounting knows that this is a task in IO wait state.
3832 * But don't do that if it is a deliberate, throttling IO wait (this task
3833 * has set its backing_dev_info: the queue against which it should throttle)
3835 void __sched
io_schedule(void)
3837 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
3839 atomic_inc(&rq
->nr_iowait
);
3841 atomic_dec(&rq
->nr_iowait
);
3844 EXPORT_SYMBOL(io_schedule
);
3846 long __sched
io_schedule_timeout(long timeout
)
3848 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
3851 atomic_inc(&rq
->nr_iowait
);
3852 ret
= schedule_timeout(timeout
);
3853 atomic_dec(&rq
->nr_iowait
);
3858 * sys_sched_get_priority_max - return maximum RT priority.
3859 * @policy: scheduling class.
3861 * this syscall returns the maximum rt_priority that can be used
3862 * by a given scheduling class.
3864 asmlinkage
long sys_sched_get_priority_max(int policy
)
3871 ret
= MAX_USER_RT_PRIO
-1;
3881 * sys_sched_get_priority_min - return minimum RT priority.
3882 * @policy: scheduling class.
3884 * this syscall returns the minimum rt_priority that can be used
3885 * by a given scheduling class.
3887 asmlinkage
long sys_sched_get_priority_min(int policy
)
3903 * sys_sched_rr_get_interval - return the default timeslice of a process.
3904 * @pid: pid of the process.
3905 * @interval: userspace pointer to the timeslice value.
3907 * this syscall writes the default timeslice value of a given process
3908 * into the user-space timespec buffer. A value of '0' means infinity.
3911 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
3913 int retval
= -EINVAL
;
3921 read_lock(&tasklist_lock
);
3922 p
= find_process_by_pid(pid
);
3926 retval
= security_task_getscheduler(p
);
3930 jiffies_to_timespec(p
->policy
& SCHED_FIFO
?
3931 0 : task_timeslice(p
), &t
);
3932 read_unlock(&tasklist_lock
);
3933 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
3937 read_unlock(&tasklist_lock
);
3941 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
3943 if (list_empty(&p
->children
)) return NULL
;
3944 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
3947 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
3949 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
3950 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
3953 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
3955 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
3956 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
3959 static void show_task(task_t
* p
)
3963 unsigned long free
= 0;
3964 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
3966 printk("%-13.13s ", p
->comm
);
3967 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
3968 if (state
< ARRAY_SIZE(stat_nam
))
3969 printk(stat_nam
[state
]);
3972 #if (BITS_PER_LONG == 32)
3973 if (state
== TASK_RUNNING
)
3974 printk(" running ");
3976 printk(" %08lX ", thread_saved_pc(p
));
3978 if (state
== TASK_RUNNING
)
3979 printk(" running task ");
3981 printk(" %016lx ", thread_saved_pc(p
));
3983 #ifdef CONFIG_DEBUG_STACK_USAGE
3985 unsigned long * n
= (unsigned long *) (p
->thread_info
+1);
3988 free
= (unsigned long) n
- (unsigned long)(p
->thread_info
+1);
3991 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
3992 if ((relative
= eldest_child(p
)))
3993 printk("%5d ", relative
->pid
);
3996 if ((relative
= younger_sibling(p
)))
3997 printk("%7d", relative
->pid
);
4000 if ((relative
= older_sibling(p
)))
4001 printk(" %5d", relative
->pid
);
4005 printk(" (L-TLB)\n");
4007 printk(" (NOTLB)\n");
4009 if (state
!= TASK_RUNNING
)
4010 show_stack(p
, NULL
);
4013 void show_state(void)
4017 #if (BITS_PER_LONG == 32)
4020 printk(" task PC pid father child younger older\n");
4024 printk(" task PC pid father child younger older\n");
4026 read_lock(&tasklist_lock
);
4027 do_each_thread(g
, p
) {
4029 * reset the NMI-timeout, listing all files on a slow
4030 * console might take alot of time:
4032 touch_nmi_watchdog();
4034 } while_each_thread(g
, p
);
4036 read_unlock(&tasklist_lock
);
4039 void __devinit
init_idle(task_t
*idle
, int cpu
)
4041 runqueue_t
*rq
= cpu_rq(cpu
);
4042 unsigned long flags
;
4044 idle
->sleep_avg
= 0;
4046 idle
->prio
= MAX_PRIO
;
4047 idle
->state
= TASK_RUNNING
;
4048 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4049 set_task_cpu(idle
, cpu
);
4051 spin_lock_irqsave(&rq
->lock
, flags
);
4052 rq
->curr
= rq
->idle
= idle
;
4053 set_tsk_need_resched(idle
);
4054 spin_unlock_irqrestore(&rq
->lock
, flags
);
4056 /* Set the preempt count _outside_ the spinlocks! */
4057 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4058 idle
->thread_info
->preempt_count
= (idle
->lock_depth
>= 0);
4060 idle
->thread_info
->preempt_count
= 0;
4065 * In a system that switches off the HZ timer nohz_cpu_mask
4066 * indicates which cpus entered this state. This is used
4067 * in the rcu update to wait only for active cpus. For system
4068 * which do not switch off the HZ timer nohz_cpu_mask should
4069 * always be CPU_MASK_NONE.
4071 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4075 * This is how migration works:
4077 * 1) we queue a migration_req_t structure in the source CPU's
4078 * runqueue and wake up that CPU's migration thread.
4079 * 2) we down() the locked semaphore => thread blocks.
4080 * 3) migration thread wakes up (implicitly it forces the migrated
4081 * thread off the CPU)
4082 * 4) it gets the migration request and checks whether the migrated
4083 * task is still in the wrong runqueue.
4084 * 5) if it's in the wrong runqueue then the migration thread removes
4085 * it and puts it into the right queue.
4086 * 6) migration thread up()s the semaphore.
4087 * 7) we wake up and the migration is done.
4091 * Change a given task's CPU affinity. Migrate the thread to a
4092 * proper CPU and schedule it away if the CPU it's executing on
4093 * is removed from the allowed bitmask.
4095 * NOTE: the caller must have a valid reference to the task, the
4096 * task must not exit() & deallocate itself prematurely. The
4097 * call is not atomic; no spinlocks may be held.
4099 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4101 unsigned long flags
;
4103 migration_req_t req
;
4106 rq
= task_rq_lock(p
, &flags
);
4107 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4112 p
->cpus_allowed
= new_mask
;
4113 /* Can the task run on the task's current CPU? If so, we're done */
4114 if (cpu_isset(task_cpu(p
), new_mask
))
4117 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4118 /* Need help from migration thread: drop lock and wait. */
4119 task_rq_unlock(rq
, &flags
);
4120 wake_up_process(rq
->migration_thread
);
4121 wait_for_completion(&req
.done
);
4122 tlb_migrate_finish(p
->mm
);
4126 task_rq_unlock(rq
, &flags
);
4130 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4133 * Move (not current) task off this cpu, onto dest cpu. We're doing
4134 * this because either it can't run here any more (set_cpus_allowed()
4135 * away from this CPU, or CPU going down), or because we're
4136 * attempting to rebalance this task on exec (sched_exec).
4138 * So we race with normal scheduler movements, but that's OK, as long
4139 * as the task is no longer on this CPU.
4141 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4143 runqueue_t
*rq_dest
, *rq_src
;
4145 if (unlikely(cpu_is_offline(dest_cpu
)))
4148 rq_src
= cpu_rq(src_cpu
);
4149 rq_dest
= cpu_rq(dest_cpu
);
4151 double_rq_lock(rq_src
, rq_dest
);
4152 /* Already moved. */
4153 if (task_cpu(p
) != src_cpu
)
4155 /* Affinity changed (again). */
4156 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4159 set_task_cpu(p
, dest_cpu
);
4162 * Sync timestamp with rq_dest's before activating.
4163 * The same thing could be achieved by doing this step
4164 * afterwards, and pretending it was a local activate.
4165 * This way is cleaner and logically correct.
4167 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4168 + rq_dest
->timestamp_last_tick
;
4169 deactivate_task(p
, rq_src
);
4170 activate_task(p
, rq_dest
, 0);
4171 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4172 resched_task(rq_dest
->curr
);
4176 double_rq_unlock(rq_src
, rq_dest
);
4180 * migration_thread - this is a highprio system thread that performs
4181 * thread migration by bumping thread off CPU then 'pushing' onto
4184 static int migration_thread(void * data
)
4187 int cpu
= (long)data
;
4190 BUG_ON(rq
->migration_thread
!= current
);
4192 set_current_state(TASK_INTERRUPTIBLE
);
4193 while (!kthread_should_stop()) {
4194 struct list_head
*head
;
4195 migration_req_t
*req
;
4197 if (current
->flags
& PF_FREEZE
)
4198 refrigerator(PF_FREEZE
);
4200 spin_lock_irq(&rq
->lock
);
4202 if (cpu_is_offline(cpu
)) {
4203 spin_unlock_irq(&rq
->lock
);
4207 if (rq
->active_balance
) {
4208 active_load_balance(rq
, cpu
);
4209 rq
->active_balance
= 0;
4212 head
= &rq
->migration_queue
;
4214 if (list_empty(head
)) {
4215 spin_unlock_irq(&rq
->lock
);
4217 set_current_state(TASK_INTERRUPTIBLE
);
4220 req
= list_entry(head
->next
, migration_req_t
, list
);
4221 list_del_init(head
->next
);
4223 if (req
->type
== REQ_MOVE_TASK
) {
4224 spin_unlock(&rq
->lock
);
4225 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4227 } else if (req
->type
== REQ_SET_DOMAIN
) {
4229 spin_unlock_irq(&rq
->lock
);
4231 spin_unlock_irq(&rq
->lock
);
4235 complete(&req
->done
);
4237 __set_current_state(TASK_RUNNING
);
4241 /* Wait for kthread_stop */
4242 set_current_state(TASK_INTERRUPTIBLE
);
4243 while (!kthread_should_stop()) {
4245 set_current_state(TASK_INTERRUPTIBLE
);
4247 __set_current_state(TASK_RUNNING
);
4251 #ifdef CONFIG_HOTPLUG_CPU
4252 /* Figure out where task on dead CPU should go, use force if neccessary. */
4253 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4259 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4260 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4261 dest_cpu
= any_online_cpu(mask
);
4263 /* On any allowed CPU? */
4264 if (dest_cpu
== NR_CPUS
)
4265 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4267 /* No more Mr. Nice Guy. */
4268 if (dest_cpu
== NR_CPUS
) {
4269 cpus_setall(tsk
->cpus_allowed
);
4270 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4273 * Don't tell them about moving exiting tasks or
4274 * kernel threads (both mm NULL), since they never
4277 if (tsk
->mm
&& printk_ratelimit())
4278 printk(KERN_INFO
"process %d (%s) no "
4279 "longer affine to cpu%d\n",
4280 tsk
->pid
, tsk
->comm
, dead_cpu
);
4282 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4286 * While a dead CPU has no uninterruptible tasks queued at this point,
4287 * it might still have a nonzero ->nr_uninterruptible counter, because
4288 * for performance reasons the counter is not stricly tracking tasks to
4289 * their home CPUs. So we just add the counter to another CPU's counter,
4290 * to keep the global sum constant after CPU-down:
4292 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4294 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4295 unsigned long flags
;
4297 local_irq_save(flags
);
4298 double_rq_lock(rq_src
, rq_dest
);
4299 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4300 rq_src
->nr_uninterruptible
= 0;
4301 double_rq_unlock(rq_src
, rq_dest
);
4302 local_irq_restore(flags
);
4305 /* Run through task list and migrate tasks from the dead cpu. */
4306 static void migrate_live_tasks(int src_cpu
)
4308 struct task_struct
*tsk
, *t
;
4310 write_lock_irq(&tasklist_lock
);
4312 do_each_thread(t
, tsk
) {
4316 if (task_cpu(tsk
) == src_cpu
)
4317 move_task_off_dead_cpu(src_cpu
, tsk
);
4318 } while_each_thread(t
, tsk
);
4320 write_unlock_irq(&tasklist_lock
);
4323 /* Schedules idle task to be the next runnable task on current CPU.
4324 * It does so by boosting its priority to highest possible and adding it to
4325 * the _front_ of runqueue. Used by CPU offline code.
4327 void sched_idle_next(void)
4329 int cpu
= smp_processor_id();
4330 runqueue_t
*rq
= this_rq();
4331 struct task_struct
*p
= rq
->idle
;
4332 unsigned long flags
;
4334 /* cpu has to be offline */
4335 BUG_ON(cpu_online(cpu
));
4337 /* Strictly not necessary since rest of the CPUs are stopped by now
4338 * and interrupts disabled on current cpu.
4340 spin_lock_irqsave(&rq
->lock
, flags
);
4342 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4343 /* Add idle task to _front_ of it's priority queue */
4344 __activate_idle_task(p
, rq
);
4346 spin_unlock_irqrestore(&rq
->lock
, flags
);
4349 /* Ensures that the idle task is using init_mm right before its cpu goes
4352 void idle_task_exit(void)
4354 struct mm_struct
*mm
= current
->active_mm
;
4356 BUG_ON(cpu_online(smp_processor_id()));
4359 switch_mm(mm
, &init_mm
, current
);
4363 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4365 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4367 /* Must be exiting, otherwise would be on tasklist. */
4368 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4370 /* Cannot have done final schedule yet: would have vanished. */
4371 BUG_ON(tsk
->flags
& PF_DEAD
);
4373 get_task_struct(tsk
);
4376 * Drop lock around migration; if someone else moves it,
4377 * that's OK. No task can be added to this CPU, so iteration is
4380 spin_unlock_irq(&rq
->lock
);
4381 move_task_off_dead_cpu(dead_cpu
, tsk
);
4382 spin_lock_irq(&rq
->lock
);
4384 put_task_struct(tsk
);
4387 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4388 static void migrate_dead_tasks(unsigned int dead_cpu
)
4391 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4393 for (arr
= 0; arr
< 2; arr
++) {
4394 for (i
= 0; i
< MAX_PRIO
; i
++) {
4395 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4396 while (!list_empty(list
))
4397 migrate_dead(dead_cpu
,
4398 list_entry(list
->next
, task_t
,
4403 #endif /* CONFIG_HOTPLUG_CPU */
4406 * migration_call - callback that gets triggered when a CPU is added.
4407 * Here we can start up the necessary migration thread for the new CPU.
4409 static int migration_call(struct notifier_block
*nfb
, unsigned long action
,
4412 int cpu
= (long)hcpu
;
4413 struct task_struct
*p
;
4414 struct runqueue
*rq
;
4415 unsigned long flags
;
4418 case CPU_UP_PREPARE
:
4419 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4422 p
->flags
|= PF_NOFREEZE
;
4423 kthread_bind(p
, cpu
);
4424 /* Must be high prio: stop_machine expects to yield to it. */
4425 rq
= task_rq_lock(p
, &flags
);
4426 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4427 task_rq_unlock(rq
, &flags
);
4428 cpu_rq(cpu
)->migration_thread
= p
;
4431 /* Strictly unneccessary, as first user will wake it. */
4432 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4434 #ifdef CONFIG_HOTPLUG_CPU
4435 case CPU_UP_CANCELED
:
4436 /* Unbind it from offline cpu so it can run. Fall thru. */
4437 kthread_bind(cpu_rq(cpu
)->migration_thread
,smp_processor_id());
4438 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4439 cpu_rq(cpu
)->migration_thread
= NULL
;
4442 migrate_live_tasks(cpu
);
4444 kthread_stop(rq
->migration_thread
);
4445 rq
->migration_thread
= NULL
;
4446 /* Idle task back to normal (off runqueue, low prio) */
4447 rq
= task_rq_lock(rq
->idle
, &flags
);
4448 deactivate_task(rq
->idle
, rq
);
4449 rq
->idle
->static_prio
= MAX_PRIO
;
4450 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4451 migrate_dead_tasks(cpu
);
4452 task_rq_unlock(rq
, &flags
);
4453 migrate_nr_uninterruptible(rq
);
4454 BUG_ON(rq
->nr_running
!= 0);
4456 /* No need to migrate the tasks: it was best-effort if
4457 * they didn't do lock_cpu_hotplug(). Just wake up
4458 * the requestors. */
4459 spin_lock_irq(&rq
->lock
);
4460 while (!list_empty(&rq
->migration_queue
)) {
4461 migration_req_t
*req
;
4462 req
= list_entry(rq
->migration_queue
.next
,
4463 migration_req_t
, list
);
4464 BUG_ON(req
->type
!= REQ_MOVE_TASK
);
4465 list_del_init(&req
->list
);
4466 complete(&req
->done
);
4468 spin_unlock_irq(&rq
->lock
);
4475 /* Register at highest priority so that task migration (migrate_all_tasks)
4476 * happens before everything else.
4478 static struct notifier_block __devinitdata migration_notifier
= {
4479 .notifier_call
= migration_call
,
4483 int __init
migration_init(void)
4485 void *cpu
= (void *)(long)smp_processor_id();
4486 /* Start one for boot CPU. */
4487 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4488 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4489 register_cpu_notifier(&migration_notifier
);
4495 #define SCHED_DOMAIN_DEBUG
4496 #ifdef SCHED_DOMAIN_DEBUG
4497 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4501 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4506 struct sched_group
*group
= sd
->groups
;
4507 cpumask_t groupmask
;
4509 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4510 cpus_clear(groupmask
);
4513 for (i
= 0; i
< level
+ 1; i
++)
4515 printk("domain %d: ", level
);
4517 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4518 printk("does not load-balance\n");
4520 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4524 printk("span %s\n", str
);
4526 if (!cpu_isset(cpu
, sd
->span
))
4527 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4528 if (!cpu_isset(cpu
, group
->cpumask
))
4529 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4532 for (i
= 0; i
< level
+ 2; i
++)
4538 printk(KERN_ERR
"ERROR: group is NULL\n");
4542 if (!group
->cpu_power
) {
4544 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4547 if (!cpus_weight(group
->cpumask
)) {
4549 printk(KERN_ERR
"ERROR: empty group\n");
4552 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4554 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4557 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4559 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4562 group
= group
->next
;
4563 } while (group
!= sd
->groups
);
4566 if (!cpus_equal(sd
->span
, groupmask
))
4567 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4573 if (!cpus_subset(groupmask
, sd
->span
))
4574 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4580 #define sched_domain_debug(sd, cpu) {}
4584 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4585 * hold the hotplug lock.
4587 void __devinit
cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
4589 migration_req_t req
;
4590 unsigned long flags
;
4591 runqueue_t
*rq
= cpu_rq(cpu
);
4594 sched_domain_debug(sd
, cpu
);
4596 spin_lock_irqsave(&rq
->lock
, flags
);
4598 if (cpu
== smp_processor_id() || !cpu_online(cpu
)) {
4601 init_completion(&req
.done
);
4602 req
.type
= REQ_SET_DOMAIN
;
4604 list_add(&req
.list
, &rq
->migration_queue
);
4608 spin_unlock_irqrestore(&rq
->lock
, flags
);
4611 wake_up_process(rq
->migration_thread
);
4612 wait_for_completion(&req
.done
);
4616 /* cpus with isolated domains */
4617 cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
4619 /* Setup the mask of cpus configured for isolated domains */
4620 static int __init
isolated_cpu_setup(char *str
)
4622 int ints
[NR_CPUS
], i
;
4624 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
4625 cpus_clear(cpu_isolated_map
);
4626 for (i
= 1; i
<= ints
[0]; i
++)
4627 if (ints
[i
] < NR_CPUS
)
4628 cpu_set(ints
[i
], cpu_isolated_map
);
4632 __setup ("isolcpus=", isolated_cpu_setup
);
4635 * init_sched_build_groups takes an array of groups, the cpumask we wish
4636 * to span, and a pointer to a function which identifies what group a CPU
4637 * belongs to. The return value of group_fn must be a valid index into the
4638 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
4639 * keep track of groups covered with a cpumask_t).
4641 * init_sched_build_groups will build a circular linked list of the groups
4642 * covered by the given span, and will set each group's ->cpumask correctly,
4643 * and ->cpu_power to 0.
4645 void __devinit
init_sched_build_groups(struct sched_group groups
[],
4646 cpumask_t span
, int (*group_fn
)(int cpu
))
4648 struct sched_group
*first
= NULL
, *last
= NULL
;
4649 cpumask_t covered
= CPU_MASK_NONE
;
4652 for_each_cpu_mask(i
, span
) {
4653 int group
= group_fn(i
);
4654 struct sched_group
*sg
= &groups
[group
];
4657 if (cpu_isset(i
, covered
))
4660 sg
->cpumask
= CPU_MASK_NONE
;
4663 for_each_cpu_mask(j
, span
) {
4664 if (group_fn(j
) != group
)
4667 cpu_set(j
, covered
);
4668 cpu_set(j
, sg
->cpumask
);
4680 #ifdef ARCH_HAS_SCHED_DOMAIN
4681 extern void __devinit
arch_init_sched_domains(void);
4682 extern void __devinit
arch_destroy_sched_domains(void);
4684 #ifdef CONFIG_SCHED_SMT
4685 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
4686 static struct sched_group sched_group_cpus
[NR_CPUS
];
4687 static int __devinit
cpu_to_cpu_group(int cpu
)
4693 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
4694 static struct sched_group sched_group_phys
[NR_CPUS
];
4695 static int __devinit
cpu_to_phys_group(int cpu
)
4697 #ifdef CONFIG_SCHED_SMT
4698 return first_cpu(cpu_sibling_map
[cpu
]);
4706 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
4707 static struct sched_group sched_group_nodes
[MAX_NUMNODES
];
4708 static int __devinit
cpu_to_node_group(int cpu
)
4710 return cpu_to_node(cpu
);
4714 #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
4716 * The domains setup code relies on siblings not spanning
4717 * multiple nodes. Make sure the architecture has a proper
4720 static void check_sibling_maps(void)
4724 for_each_online_cpu(i
) {
4725 for_each_cpu_mask(j
, cpu_sibling_map
[i
]) {
4726 if (cpu_to_node(i
) != cpu_to_node(j
)) {
4727 printk(KERN_INFO
"warning: CPU %d siblings map "
4728 "to different node - isolating "
4730 cpu_sibling_map
[i
] = cpumask_of_cpu(i
);
4739 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
4741 static void __devinit
arch_init_sched_domains(void)
4744 cpumask_t cpu_default_map
;
4746 #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
4747 check_sibling_maps();
4750 * Setup mask for cpus without special case scheduling requirements.
4751 * For now this just excludes isolated cpus, but could be used to
4752 * exclude other special cases in the future.
4754 cpus_complement(cpu_default_map
, cpu_isolated_map
);
4755 cpus_and(cpu_default_map
, cpu_default_map
, cpu_online_map
);
4758 * Set up domains. Isolated domains just stay on the dummy domain.
4760 for_each_cpu_mask(i
, cpu_default_map
) {
4762 struct sched_domain
*sd
= NULL
, *p
;
4763 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
4765 cpus_and(nodemask
, nodemask
, cpu_default_map
);
4768 sd
= &per_cpu(node_domains
, i
);
4769 group
= cpu_to_node_group(i
);
4771 sd
->span
= cpu_default_map
;
4772 sd
->groups
= &sched_group_nodes
[group
];
4776 sd
= &per_cpu(phys_domains
, i
);
4777 group
= cpu_to_phys_group(i
);
4779 sd
->span
= nodemask
;
4781 sd
->groups
= &sched_group_phys
[group
];
4783 #ifdef CONFIG_SCHED_SMT
4785 sd
= &per_cpu(cpu_domains
, i
);
4786 group
= cpu_to_cpu_group(i
);
4787 *sd
= SD_SIBLING_INIT
;
4788 sd
->span
= cpu_sibling_map
[i
];
4789 cpus_and(sd
->span
, sd
->span
, cpu_default_map
);
4791 sd
->groups
= &sched_group_cpus
[group
];
4795 #ifdef CONFIG_SCHED_SMT
4796 /* Set up CPU (sibling) groups */
4797 for_each_online_cpu(i
) {
4798 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
4799 cpus_and(this_sibling_map
, this_sibling_map
, cpu_default_map
);
4800 if (i
!= first_cpu(this_sibling_map
))
4803 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
4808 /* Set up physical groups */
4809 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
4810 cpumask_t nodemask
= node_to_cpumask(i
);
4812 cpus_and(nodemask
, nodemask
, cpu_default_map
);
4813 if (cpus_empty(nodemask
))
4816 init_sched_build_groups(sched_group_phys
, nodemask
,
4817 &cpu_to_phys_group
);
4821 /* Set up node groups */
4822 init_sched_build_groups(sched_group_nodes
, cpu_default_map
,
4823 &cpu_to_node_group
);
4826 /* Calculate CPU power for physical packages and nodes */
4827 for_each_cpu_mask(i
, cpu_default_map
) {
4829 struct sched_domain
*sd
;
4830 #ifdef CONFIG_SCHED_SMT
4831 sd
= &per_cpu(cpu_domains
, i
);
4832 power
= SCHED_LOAD_SCALE
;
4833 sd
->groups
->cpu_power
= power
;
4836 sd
= &per_cpu(phys_domains
, i
);
4837 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
4838 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
4839 sd
->groups
->cpu_power
= power
;
4842 if (i
== first_cpu(sd
->groups
->cpumask
)) {
4843 /* Only add "power" once for each physical package. */
4844 sd
= &per_cpu(node_domains
, i
);
4845 sd
->groups
->cpu_power
+= power
;
4850 /* Attach the domains */
4851 for_each_online_cpu(i
) {
4852 struct sched_domain
*sd
;
4853 #ifdef CONFIG_SCHED_SMT
4854 sd
= &per_cpu(cpu_domains
, i
);
4856 sd
= &per_cpu(phys_domains
, i
);
4858 cpu_attach_domain(sd
, i
);
4862 #ifdef CONFIG_HOTPLUG_CPU
4863 static void __devinit
arch_destroy_sched_domains(void)
4865 /* Do nothing: everything is statically allocated. */
4869 #endif /* ARCH_HAS_SCHED_DOMAIN */
4872 * Initial dummy domain for early boot and for hotplug cpu. Being static,
4873 * it is initialized to zero, so all balancing flags are cleared which is
4876 static struct sched_domain sched_domain_dummy
;
4878 #ifdef CONFIG_HOTPLUG_CPU
4880 * Force a reinitialization of the sched domains hierarchy. The domains
4881 * and groups cannot be updated in place without racing with the balancing
4882 * code, so we temporarily attach all running cpus to a "dummy" domain
4883 * which will prevent rebalancing while the sched domains are recalculated.
4885 static int update_sched_domains(struct notifier_block
*nfb
,
4886 unsigned long action
, void *hcpu
)
4891 case CPU_UP_PREPARE
:
4892 case CPU_DOWN_PREPARE
:
4893 for_each_online_cpu(i
)
4894 cpu_attach_domain(&sched_domain_dummy
, i
);
4895 arch_destroy_sched_domains();
4898 case CPU_UP_CANCELED
:
4899 case CPU_DOWN_FAILED
:
4903 * Fall through and re-initialise the domains.
4910 /* The hotplug lock is already held by cpu_up/cpu_down */
4911 arch_init_sched_domains();
4917 void __init
sched_init_smp(void)
4920 arch_init_sched_domains();
4921 unlock_cpu_hotplug();
4922 /* XXX: Theoretical race here - CPU may be hotplugged now */
4923 hotcpu_notifier(update_sched_domains
, 0);
4926 void __init
sched_init_smp(void)
4929 #endif /* CONFIG_SMP */
4931 int in_sched_functions(unsigned long addr
)
4933 /* Linker adds these: start and end of __sched functions */
4934 extern char __sched_text_start
[], __sched_text_end
[];
4935 return in_lock_functions(addr
) ||
4936 (addr
>= (unsigned long)__sched_text_start
4937 && addr
< (unsigned long)__sched_text_end
);
4940 void __init
sched_init(void)
4945 for (i
= 0; i
< NR_CPUS
; i
++) {
4946 prio_array_t
*array
;
4949 spin_lock_init(&rq
->lock
);
4950 rq
->active
= rq
->arrays
;
4951 rq
->expired
= rq
->arrays
+ 1;
4952 rq
->best_expired_prio
= MAX_PRIO
;
4955 rq
->sd
= &sched_domain_dummy
;
4957 rq
->active_balance
= 0;
4959 rq
->migration_thread
= NULL
;
4960 INIT_LIST_HEAD(&rq
->migration_queue
);
4962 atomic_set(&rq
->nr_iowait
, 0);
4964 for (j
= 0; j
< 2; j
++) {
4965 array
= rq
->arrays
+ j
;
4966 for (k
= 0; k
< MAX_PRIO
; k
++) {
4967 INIT_LIST_HEAD(array
->queue
+ k
);
4968 __clear_bit(k
, array
->bitmap
);
4970 // delimiter for bitsearch
4971 __set_bit(MAX_PRIO
, array
->bitmap
);
4976 * The boot idle thread does lazy MMU switching as well:
4978 atomic_inc(&init_mm
.mm_count
);
4979 enter_lazy_tlb(&init_mm
, current
);
4982 * Make us the idle thread. Technically, schedule() should not be
4983 * called from this thread, however somewhere below it might be,
4984 * but because we are the idle thread, we just pick up running again
4985 * when this runqueue becomes "idle".
4987 init_idle(current
, smp_processor_id());
4990 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4991 void __might_sleep(char *file
, int line
)
4993 #if defined(in_atomic)
4994 static unsigned long prev_jiffy
; /* ratelimiting */
4996 if ((in_atomic() || irqs_disabled()) &&
4997 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
4998 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
5000 prev_jiffy
= jiffies
;
5001 printk(KERN_ERR
"Debug: sleeping function called from invalid"
5002 " context at %s:%d\n", file
, line
);
5003 printk("in_atomic():%d, irqs_disabled():%d\n",
5004 in_atomic(), irqs_disabled());
5009 EXPORT_SYMBOL(__might_sleep
);
5012 #ifdef CONFIG_MAGIC_SYSRQ
5013 void normalize_rt_tasks(void)
5015 struct task_struct
*p
;
5016 prio_array_t
*array
;
5017 unsigned long flags
;
5020 read_lock_irq(&tasklist_lock
);
5021 for_each_process (p
) {
5025 rq
= task_rq_lock(p
, &flags
);
5029 deactivate_task(p
, task_rq(p
));
5030 __setscheduler(p
, SCHED_NORMAL
, 0);
5032 __activate_task(p
, task_rq(p
));
5033 resched_task(rq
->curr
);
5036 task_rq_unlock(rq
, &flags
);
5038 read_unlock_irq(&tasklist_lock
);
5041 #endif /* CONFIG_MAGIC_SYSRQ */