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 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
[3];
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)
271 #ifndef prepare_arch_switch
272 # define prepare_arch_switch(next) do { } while (0)
274 #ifndef finish_arch_switch
275 # define finish_arch_switch(prev) do { } while (0)
278 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
279 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
281 return rq
->curr
== p
;
284 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
288 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
290 spin_unlock_irq(&rq
->lock
);
293 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
294 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
299 return rq
->curr
== p
;
303 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
307 * We can optimise this out completely for !SMP, because the
308 * SMP rebalancing from interrupt is the only thing that cares
313 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
314 spin_unlock_irq(&rq
->lock
);
316 spin_unlock(&rq
->lock
);
320 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
324 * After ->oncpu is cleared, the task can be moved to a different CPU.
325 * We must ensure this doesn't happen until the switch is completely
331 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
335 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
338 * task_rq_lock - lock the runqueue a given task resides on and disable
339 * interrupts. Note the ordering: we can safely lookup the task_rq without
340 * explicitly disabling preemption.
342 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
348 local_irq_save(*flags
);
350 spin_lock(&rq
->lock
);
351 if (unlikely(rq
!= task_rq(p
))) {
352 spin_unlock_irqrestore(&rq
->lock
, *flags
);
353 goto repeat_lock_task
;
358 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
361 spin_unlock_irqrestore(&rq
->lock
, *flags
);
364 #ifdef CONFIG_SCHEDSTATS
366 * bump this up when changing the output format or the meaning of an existing
367 * format, so that tools can adapt (or abort)
369 #define SCHEDSTAT_VERSION 12
371 static int show_schedstat(struct seq_file
*seq
, void *v
)
375 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
376 seq_printf(seq
, "timestamp %lu\n", jiffies
);
377 for_each_online_cpu(cpu
) {
378 runqueue_t
*rq
= cpu_rq(cpu
);
380 struct sched_domain
*sd
;
384 /* runqueue-specific stats */
386 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
387 cpu
, rq
->yld_both_empty
,
388 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
389 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
390 rq
->ttwu_cnt
, rq
->ttwu_local
,
391 rq
->rq_sched_info
.cpu_time
,
392 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
394 seq_printf(seq
, "\n");
397 /* domain-specific stats */
398 for_each_domain(cpu
, sd
) {
399 enum idle_type itype
;
400 char mask_str
[NR_CPUS
];
402 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
403 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
404 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
406 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
408 sd
->lb_balanced
[itype
],
409 sd
->lb_failed
[itype
],
410 sd
->lb_imbalance
[itype
],
411 sd
->lb_gained
[itype
],
412 sd
->lb_hot_gained
[itype
],
413 sd
->lb_nobusyq
[itype
],
414 sd
->lb_nobusyg
[itype
]);
416 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
417 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
418 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
419 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
420 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
427 static int schedstat_open(struct inode
*inode
, struct file
*file
)
429 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
430 char *buf
= kmalloc(size
, GFP_KERNEL
);
436 res
= single_open(file
, show_schedstat
, NULL
);
438 m
= file
->private_data
;
446 struct file_operations proc_schedstat_operations
= {
447 .open
= schedstat_open
,
450 .release
= single_release
,
453 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
454 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
455 #else /* !CONFIG_SCHEDSTATS */
456 # define schedstat_inc(rq, field) do { } while (0)
457 # define schedstat_add(rq, field, amt) do { } while (0)
461 * rq_lock - lock a given runqueue and disable interrupts.
463 static inline runqueue_t
*this_rq_lock(void)
470 spin_lock(&rq
->lock
);
475 #ifdef CONFIG_SCHEDSTATS
477 * Called when a process is dequeued from the active array and given
478 * the cpu. We should note that with the exception of interactive
479 * tasks, the expired queue will become the active queue after the active
480 * queue is empty, without explicitly dequeuing and requeuing tasks in the
481 * expired queue. (Interactive tasks may be requeued directly to the
482 * active queue, thus delaying tasks in the expired queue from running;
483 * see scheduler_tick()).
485 * This function is only called from sched_info_arrive(), rather than
486 * dequeue_task(). Even though a task may be queued and dequeued multiple
487 * times as it is shuffled about, we're really interested in knowing how
488 * long it was from the *first* time it was queued to the time that it
491 static inline void sched_info_dequeued(task_t
*t
)
493 t
->sched_info
.last_queued
= 0;
497 * Called when a task finally hits the cpu. We can now calculate how
498 * long it was waiting to run. We also note when it began so that we
499 * can keep stats on how long its timeslice is.
501 static inline void sched_info_arrive(task_t
*t
)
503 unsigned long now
= jiffies
, diff
= 0;
504 struct runqueue
*rq
= task_rq(t
);
506 if (t
->sched_info
.last_queued
)
507 diff
= now
- t
->sched_info
.last_queued
;
508 sched_info_dequeued(t
);
509 t
->sched_info
.run_delay
+= diff
;
510 t
->sched_info
.last_arrival
= now
;
511 t
->sched_info
.pcnt
++;
516 rq
->rq_sched_info
.run_delay
+= diff
;
517 rq
->rq_sched_info
.pcnt
++;
521 * Called when a process is queued into either the active or expired
522 * array. The time is noted and later used to determine how long we
523 * had to wait for us to reach the cpu. Since the expired queue will
524 * become the active queue after active queue is empty, without dequeuing
525 * and requeuing any tasks, we are interested in queuing to either. It
526 * is unusual but not impossible for tasks to be dequeued and immediately
527 * requeued in the same or another array: this can happen in sched_yield(),
528 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
531 * This function is only called from enqueue_task(), but also only updates
532 * the timestamp if it is already not set. It's assumed that
533 * sched_info_dequeued() will clear that stamp when appropriate.
535 static inline void sched_info_queued(task_t
*t
)
537 if (!t
->sched_info
.last_queued
)
538 t
->sched_info
.last_queued
= jiffies
;
542 * Called when a process ceases being the active-running process, either
543 * voluntarily or involuntarily. Now we can calculate how long we ran.
545 static inline void sched_info_depart(task_t
*t
)
547 struct runqueue
*rq
= task_rq(t
);
548 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
550 t
->sched_info
.cpu_time
+= diff
;
553 rq
->rq_sched_info
.cpu_time
+= diff
;
557 * Called when tasks are switched involuntarily due, typically, to expiring
558 * their time slice. (This may also be called when switching to or from
559 * the idle task.) We are only called when prev != next.
561 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
563 struct runqueue
*rq
= task_rq(prev
);
566 * prev now departs the cpu. It's not interesting to record
567 * stats about how efficient we were at scheduling the idle
570 if (prev
!= rq
->idle
)
571 sched_info_depart(prev
);
573 if (next
!= rq
->idle
)
574 sched_info_arrive(next
);
577 #define sched_info_queued(t) do { } while (0)
578 #define sched_info_switch(t, next) do { } while (0)
579 #endif /* CONFIG_SCHEDSTATS */
582 * Adding/removing a task to/from a priority array:
584 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
587 list_del(&p
->run_list
);
588 if (list_empty(array
->queue
+ p
->prio
))
589 __clear_bit(p
->prio
, array
->bitmap
);
592 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
594 sched_info_queued(p
);
595 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
596 __set_bit(p
->prio
, array
->bitmap
);
602 * Put task to the end of the run list without the overhead of dequeue
603 * followed by enqueue.
605 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
607 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
610 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
612 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
613 __set_bit(p
->prio
, array
->bitmap
);
619 * effective_prio - return the priority that is based on the static
620 * priority but is modified by bonuses/penalties.
622 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
623 * into the -5 ... 0 ... +5 bonus/penalty range.
625 * We use 25% of the full 0...39 priority range so that:
627 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
628 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
630 * Both properties are important to certain workloads.
632 static int effective_prio(task_t
*p
)
639 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
641 prio
= p
->static_prio
- bonus
;
642 if (prio
< MAX_RT_PRIO
)
644 if (prio
> MAX_PRIO
-1)
650 * __activate_task - move a task to the runqueue.
652 static inline void __activate_task(task_t
*p
, runqueue_t
*rq
)
654 enqueue_task(p
, rq
->active
);
659 * __activate_idle_task - move idle task to the _front_ of runqueue.
661 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
663 enqueue_task_head(p
, rq
->active
);
667 static void recalc_task_prio(task_t
*p
, unsigned long long now
)
669 /* Caller must always ensure 'now >= p->timestamp' */
670 unsigned long long __sleep_time
= now
- p
->timestamp
;
671 unsigned long sleep_time
;
673 if (__sleep_time
> NS_MAX_SLEEP_AVG
)
674 sleep_time
= NS_MAX_SLEEP_AVG
;
676 sleep_time
= (unsigned long)__sleep_time
;
678 if (likely(sleep_time
> 0)) {
680 * User tasks that sleep a long time are categorised as
681 * idle and will get just interactive status to stay active &
682 * prevent them suddenly becoming cpu hogs and starving
685 if (p
->mm
&& p
->activated
!= -1 &&
686 sleep_time
> INTERACTIVE_SLEEP(p
)) {
687 p
->sleep_avg
= JIFFIES_TO_NS(MAX_SLEEP_AVG
-
691 * The lower the sleep avg a task has the more
692 * rapidly it will rise with sleep time.
694 sleep_time
*= (MAX_BONUS
- CURRENT_BONUS(p
)) ? : 1;
697 * Tasks waking from uninterruptible sleep are
698 * limited in their sleep_avg rise as they
699 * are likely to be waiting on I/O
701 if (p
->activated
== -1 && p
->mm
) {
702 if (p
->sleep_avg
>= INTERACTIVE_SLEEP(p
))
704 else if (p
->sleep_avg
+ sleep_time
>=
705 INTERACTIVE_SLEEP(p
)) {
706 p
->sleep_avg
= INTERACTIVE_SLEEP(p
);
712 * This code gives a bonus to interactive tasks.
714 * The boost works by updating the 'average sleep time'
715 * value here, based on ->timestamp. The more time a
716 * task spends sleeping, the higher the average gets -
717 * and the higher the priority boost gets as well.
719 p
->sleep_avg
+= sleep_time
;
721 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
722 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
726 p
->prio
= effective_prio(p
);
730 * activate_task - move a task to the runqueue and do priority recalculation
732 * Update all the scheduling statistics stuff. (sleep average
733 * calculation, priority modifiers, etc.)
735 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
737 unsigned long long now
;
742 /* Compensate for drifting sched_clock */
743 runqueue_t
*this_rq
= this_rq();
744 now
= (now
- this_rq
->timestamp_last_tick
)
745 + rq
->timestamp_last_tick
;
749 recalc_task_prio(p
, now
);
752 * This checks to make sure it's not an uninterruptible task
753 * that is now waking up.
757 * Tasks which were woken up by interrupts (ie. hw events)
758 * are most likely of interactive nature. So we give them
759 * the credit of extending their sleep time to the period
760 * of time they spend on the runqueue, waiting for execution
761 * on a CPU, first time around:
767 * Normal first-time wakeups get a credit too for
768 * on-runqueue time, but it will be weighted down:
775 __activate_task(p
, rq
);
779 * deactivate_task - remove a task from the runqueue.
781 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
784 dequeue_task(p
, p
->array
);
789 * resched_task - mark a task 'to be rescheduled now'.
791 * On UP this means the setting of the need_resched flag, on SMP it
792 * might also involve a cross-CPU call to trigger the scheduler on
796 static void resched_task(task_t
*p
)
798 int need_resched
, nrpolling
;
800 assert_spin_locked(&task_rq(p
)->lock
);
802 /* minimise the chance of sending an interrupt to poll_idle() */
803 nrpolling
= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
804 need_resched
= test_and_set_tsk_thread_flag(p
,TIF_NEED_RESCHED
);
805 nrpolling
|= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
807 if (!need_resched
&& !nrpolling
&& (task_cpu(p
) != smp_processor_id()))
808 smp_send_reschedule(task_cpu(p
));
811 static inline void resched_task(task_t
*p
)
813 set_tsk_need_resched(p
);
818 * task_curr - is this task currently executing on a CPU?
819 * @p: the task in question.
821 inline int task_curr(const task_t
*p
)
823 return cpu_curr(task_cpu(p
)) == p
;
833 struct list_head list
;
834 enum request_type type
;
836 /* For REQ_MOVE_TASK */
840 /* For REQ_SET_DOMAIN */
841 struct sched_domain
*sd
;
843 struct completion done
;
847 * The task's runqueue lock must be held.
848 * Returns true if you have to wait for migration thread.
850 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
852 runqueue_t
*rq
= task_rq(p
);
855 * If the task is not on a runqueue (and not running), then
856 * it is sufficient to simply update the task's cpu field.
858 if (!p
->array
&& !task_running(rq
, p
)) {
859 set_task_cpu(p
, dest_cpu
);
863 init_completion(&req
->done
);
864 req
->type
= REQ_MOVE_TASK
;
866 req
->dest_cpu
= dest_cpu
;
867 list_add(&req
->list
, &rq
->migration_queue
);
872 * wait_task_inactive - wait for a thread to unschedule.
874 * The caller must ensure that the task *will* unschedule sometime soon,
875 * else this function might spin for a *long* time. This function can't
876 * be called with interrupts off, or it may introduce deadlock with
877 * smp_call_function() if an IPI is sent by the same process we are
878 * waiting to become inactive.
880 void wait_task_inactive(task_t
* p
)
887 rq
= task_rq_lock(p
, &flags
);
888 /* Must be off runqueue entirely, not preempted. */
889 if (unlikely(p
->array
|| task_running(rq
, p
))) {
890 /* If it's preempted, we yield. It could be a while. */
891 preempted
= !task_running(rq
, p
);
892 task_rq_unlock(rq
, &flags
);
898 task_rq_unlock(rq
, &flags
);
902 * kick_process - kick a running thread to enter/exit the kernel
903 * @p: the to-be-kicked thread
905 * Cause a process which is running on another CPU to enter
906 * kernel-mode, without any delay. (to get signals handled.)
908 * NOTE: this function doesnt have to take the runqueue lock,
909 * because all it wants to ensure is that the remote task enters
910 * the kernel. If the IPI races and the task has been migrated
911 * to another CPU then no harm is done and the purpose has been
914 void kick_process(task_t
*p
)
920 if ((cpu
!= smp_processor_id()) && task_curr(p
))
921 smp_send_reschedule(cpu
);
926 * Return a low guess at the load of a migration-source cpu.
928 * We want to under-estimate the load of migration sources, to
929 * balance conservatively.
931 static inline unsigned long source_load(int cpu
, int type
)
933 runqueue_t
*rq
= cpu_rq(cpu
);
934 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
938 return min(rq
->cpu_load
[type
-1], load_now
);
942 * Return a high guess at the load of a migration-target cpu
944 static inline unsigned long target_load(int cpu
, int type
)
946 runqueue_t
*rq
= cpu_rq(cpu
);
947 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
951 return max(rq
->cpu_load
[type
-1], load_now
);
955 * find_idlest_group finds and returns the least busy CPU group within the
958 static struct sched_group
*
959 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
961 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
962 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
963 int load_idx
= sd
->forkexec_idx
;
964 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
967 unsigned long load
, avg_load
;
971 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
972 /* XXX: put a cpus allowed check */
974 /* Tally up the load of all CPUs in the group */
977 for_each_cpu_mask(i
, group
->cpumask
) {
978 /* Bias balancing toward cpus of our domain */
980 load
= source_load(i
, load_idx
);
982 load
= target_load(i
, load_idx
);
987 /* Adjust by relative CPU power of the group */
988 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
991 this_load
= avg_load
;
993 } else if (avg_load
< min_load
) {
998 } while (group
!= sd
->groups
);
1000 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1006 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1008 static int find_idlest_cpu(struct sched_group
*group
, int this_cpu
)
1010 unsigned long load
, min_load
= ULONG_MAX
;
1014 for_each_cpu_mask(i
, group
->cpumask
) {
1015 load
= source_load(i
, 0);
1017 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1030 * wake_idle() will wake a task on an idle cpu if task->cpu is
1031 * not idle and an idle cpu is available. The span of cpus to
1032 * search starts with cpus closest then further out as needed,
1033 * so we always favor a closer, idle cpu.
1035 * Returns the CPU we should wake onto.
1037 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1038 static int wake_idle(int cpu
, task_t
*p
)
1041 struct sched_domain
*sd
;
1047 for_each_domain(cpu
, sd
) {
1048 if (sd
->flags
& SD_WAKE_IDLE
) {
1049 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1050 for_each_cpu_mask(i
, tmp
) {
1061 static inline int wake_idle(int cpu
, task_t
*p
)
1068 * try_to_wake_up - wake up a thread
1069 * @p: the to-be-woken-up thread
1070 * @state: the mask of task states that can be woken
1071 * @sync: do a synchronous wakeup?
1073 * Put it on the run-queue if it's not already there. The "current"
1074 * thread is always on the run-queue (except when the actual
1075 * re-schedule is in progress), and as such you're allowed to do
1076 * the simpler "current->state = TASK_RUNNING" to mark yourself
1077 * runnable without the overhead of this.
1079 * returns failure only if the task is already active.
1081 static int try_to_wake_up(task_t
* p
, unsigned int state
, int sync
)
1083 int cpu
, this_cpu
, success
= 0;
1084 unsigned long flags
;
1088 unsigned long load
, this_load
;
1089 struct sched_domain
*sd
, *this_sd
= NULL
;
1093 rq
= task_rq_lock(p
, &flags
);
1094 old_state
= p
->state
;
1095 if (!(old_state
& state
))
1102 this_cpu
= smp_processor_id();
1105 if (unlikely(task_running(rq
, p
)))
1110 schedstat_inc(rq
, ttwu_cnt
);
1111 if (cpu
== this_cpu
) {
1112 schedstat_inc(rq
, ttwu_local
);
1116 for_each_domain(this_cpu
, sd
) {
1117 if (cpu_isset(cpu
, sd
->span
)) {
1118 schedstat_inc(sd
, ttwu_wake_remote
);
1124 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1128 * Check for affine wakeup and passive balancing possibilities.
1131 int idx
= this_sd
->wake_idx
;
1132 unsigned int imbalance
;
1134 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1136 load
= source_load(cpu
, idx
);
1137 this_load
= target_load(this_cpu
, idx
);
1139 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1141 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1142 unsigned long tl
= this_load
;
1144 * If sync wakeup then subtract the (maximum possible)
1145 * effect of the currently running task from the load
1146 * of the current CPU:
1149 tl
-= SCHED_LOAD_SCALE
;
1152 tl
+ target_load(cpu
, idx
) <= SCHED_LOAD_SCALE
) ||
1153 100*(tl
+ SCHED_LOAD_SCALE
) <= imbalance
*load
) {
1155 * This domain has SD_WAKE_AFFINE and
1156 * p is cache cold in this domain, and
1157 * there is no bad imbalance.
1159 schedstat_inc(this_sd
, ttwu_move_affine
);
1165 * Start passive balancing when half the imbalance_pct
1168 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1169 if (imbalance
*this_load
<= 100*load
) {
1170 schedstat_inc(this_sd
, ttwu_move_balance
);
1176 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1178 new_cpu
= wake_idle(new_cpu
, p
);
1179 if (new_cpu
!= cpu
) {
1180 set_task_cpu(p
, new_cpu
);
1181 task_rq_unlock(rq
, &flags
);
1182 /* might preempt at this point */
1183 rq
= task_rq_lock(p
, &flags
);
1184 old_state
= p
->state
;
1185 if (!(old_state
& state
))
1190 this_cpu
= smp_processor_id();
1195 #endif /* CONFIG_SMP */
1196 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1197 rq
->nr_uninterruptible
--;
1199 * Tasks on involuntary sleep don't earn
1200 * sleep_avg beyond just interactive state.
1206 * Sync wakeups (i.e. those types of wakeups where the waker
1207 * has indicated that it will leave the CPU in short order)
1208 * don't trigger a preemption, if the woken up task will run on
1209 * this cpu. (in this case the 'I will reschedule' promise of
1210 * the waker guarantees that the freshly woken up task is going
1211 * to be considered on this CPU.)
1213 activate_task(p
, rq
, cpu
== this_cpu
);
1214 if (!sync
|| cpu
!= this_cpu
) {
1215 if (TASK_PREEMPTS_CURR(p
, rq
))
1216 resched_task(rq
->curr
);
1221 p
->state
= TASK_RUNNING
;
1223 task_rq_unlock(rq
, &flags
);
1228 int fastcall
wake_up_process(task_t
* p
)
1230 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1231 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1234 EXPORT_SYMBOL(wake_up_process
);
1236 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1238 return try_to_wake_up(p
, state
, 0);
1242 * Perform scheduler related setup for a newly forked process p.
1243 * p is forked by current.
1245 void fastcall
sched_fork(task_t
*p
)
1248 * We mark the process as running here, but have not actually
1249 * inserted it onto the runqueue yet. This guarantees that
1250 * nobody will actually run it, and a signal or other external
1251 * event cannot wake it up and insert it on the runqueue either.
1253 p
->state
= TASK_RUNNING
;
1254 INIT_LIST_HEAD(&p
->run_list
);
1256 #ifdef CONFIG_SCHEDSTATS
1257 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1259 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1262 #ifdef CONFIG_PREEMPT
1263 /* Want to start with kernel preemption disabled. */
1264 p
->thread_info
->preempt_count
= 1;
1267 * Share the timeslice between parent and child, thus the
1268 * total amount of pending timeslices in the system doesn't change,
1269 * resulting in more scheduling fairness.
1271 local_irq_disable();
1272 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1274 * The remainder of the first timeslice might be recovered by
1275 * the parent if the child exits early enough.
1277 p
->first_time_slice
= 1;
1278 current
->time_slice
>>= 1;
1279 p
->timestamp
= sched_clock();
1280 if (unlikely(!current
->time_slice
)) {
1282 * This case is rare, it happens when the parent has only
1283 * a single jiffy left from its timeslice. Taking the
1284 * runqueue lock is not a problem.
1286 current
->time_slice
= 1;
1296 * wake_up_new_task - wake up a newly created task for the first time.
1298 * This function will do some initial scheduler statistics housekeeping
1299 * that must be done for every newly created context, then puts the task
1300 * on the runqueue and wakes it.
1302 void fastcall
wake_up_new_task(task_t
* p
, unsigned long clone_flags
)
1304 unsigned long flags
;
1306 runqueue_t
*rq
, *this_rq
;
1308 struct sched_domain
*tmp
, *sd
= NULL
;
1311 rq
= task_rq_lock(p
, &flags
);
1312 BUG_ON(p
->state
!= TASK_RUNNING
);
1313 this_cpu
= smp_processor_id();
1317 for_each_domain(cpu
, tmp
)
1318 if (tmp
->flags
& SD_BALANCE_FORK
)
1323 struct sched_group
*group
;
1325 schedstat_inc(sd
, sbf_cnt
);
1327 group
= find_idlest_group(sd
, p
, cpu
);
1329 schedstat_inc(sd
, sbf_balanced
);
1330 goto no_forkbalance
;
1333 new_cpu
= find_idlest_cpu(group
, cpu
);
1334 if (new_cpu
== -1 || new_cpu
== cpu
) {
1335 schedstat_inc(sd
, sbf_balanced
);
1336 goto no_forkbalance
;
1339 if (cpu_isset(new_cpu
, p
->cpus_allowed
)) {
1340 schedstat_inc(sd
, sbf_pushed
);
1341 set_task_cpu(p
, new_cpu
);
1342 task_rq_unlock(rq
, &flags
);
1343 rq
= task_rq_lock(p
, &flags
);
1351 * We decrease the sleep average of forking parents
1352 * and children as well, to keep max-interactive tasks
1353 * from forking tasks that are max-interactive. The parent
1354 * (current) is done further down, under its lock.
1356 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1357 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1359 p
->prio
= effective_prio(p
);
1361 if (likely(cpu
== this_cpu
)) {
1362 if (!(clone_flags
& CLONE_VM
)) {
1364 * The VM isn't cloned, so we're in a good position to
1365 * do child-runs-first in anticipation of an exec. This
1366 * usually avoids a lot of COW overhead.
1368 if (unlikely(!current
->array
))
1369 __activate_task(p
, rq
);
1371 p
->prio
= current
->prio
;
1372 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1373 p
->array
= current
->array
;
1374 p
->array
->nr_active
++;
1379 /* Run child last */
1380 __activate_task(p
, rq
);
1382 * We skip the following code due to cpu == this_cpu
1384 * task_rq_unlock(rq, &flags);
1385 * this_rq = task_rq_lock(current, &flags);
1389 this_rq
= cpu_rq(this_cpu
);
1392 * Not the local CPU - must adjust timestamp. This should
1393 * get optimised away in the !CONFIG_SMP case.
1395 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1396 + rq
->timestamp_last_tick
;
1397 __activate_task(p
, rq
);
1398 if (TASK_PREEMPTS_CURR(p
, rq
))
1399 resched_task(rq
->curr
);
1402 * Parent and child are on different CPUs, now get the
1403 * parent runqueue to update the parent's ->sleep_avg:
1405 task_rq_unlock(rq
, &flags
);
1406 this_rq
= task_rq_lock(current
, &flags
);
1408 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1409 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1410 task_rq_unlock(this_rq
, &flags
);
1414 * Potentially available exiting-child timeslices are
1415 * retrieved here - this way the parent does not get
1416 * penalized for creating too many threads.
1418 * (this cannot be used to 'generate' timeslices
1419 * artificially, because any timeslice recovered here
1420 * was given away by the parent in the first place.)
1422 void fastcall
sched_exit(task_t
* p
)
1424 unsigned long flags
;
1428 * If the child was a (relative-) CPU hog then decrease
1429 * the sleep_avg of the parent as well.
1431 rq
= task_rq_lock(p
->parent
, &flags
);
1432 if (p
->first_time_slice
) {
1433 p
->parent
->time_slice
+= p
->time_slice
;
1434 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1435 p
->parent
->time_slice
= task_timeslice(p
);
1437 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1438 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1439 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1441 task_rq_unlock(rq
, &flags
);
1445 * prepare_task_switch - prepare to switch tasks
1446 * @rq: the runqueue preparing to switch
1447 * @next: the task we are going to switch to.
1449 * This is called with the rq lock held and interrupts off. It must
1450 * be paired with a subsequent finish_task_switch after the context
1453 * prepare_task_switch sets up locking and calls architecture specific
1456 static inline void prepare_task_switch(runqueue_t
*rq
, task_t
*next
)
1458 prepare_lock_switch(rq
, next
);
1459 prepare_arch_switch(next
);
1463 * finish_task_switch - clean up after a task-switch
1464 * @prev: the thread we just switched away from.
1466 * finish_task_switch must be called after the context switch, paired
1467 * with a prepare_task_switch call before the context switch.
1468 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1469 * and do any other architecture-specific cleanup actions.
1471 * Note that we may have delayed dropping an mm in context_switch(). If
1472 * so, we finish that here outside of the runqueue lock. (Doing it
1473 * with the lock held can cause deadlocks; see schedule() for
1476 static inline void finish_task_switch(runqueue_t
*rq
, task_t
*prev
)
1477 __releases(rq
->lock
)
1479 struct mm_struct
*mm
= rq
->prev_mm
;
1480 unsigned long prev_task_flags
;
1485 * A task struct has one reference for the use as "current".
1486 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1487 * calls schedule one last time. The schedule call will never return,
1488 * and the scheduled task must drop that reference.
1489 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1490 * still held, otherwise prev could be scheduled on another cpu, die
1491 * there before we look at prev->state, and then the reference would
1493 * Manfred Spraul <manfred@colorfullife.com>
1495 prev_task_flags
= prev
->flags
;
1496 finish_arch_switch(prev
);
1497 finish_lock_switch(rq
, prev
);
1500 if (unlikely(prev_task_flags
& PF_DEAD
))
1501 put_task_struct(prev
);
1505 * schedule_tail - first thing a freshly forked thread must call.
1506 * @prev: the thread we just switched away from.
1508 asmlinkage
void schedule_tail(task_t
*prev
)
1509 __releases(rq
->lock
)
1511 runqueue_t
*rq
= this_rq();
1512 finish_task_switch(rq
, prev
);
1513 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1514 /* In this case, finish_task_switch does not reenable preemption */
1517 if (current
->set_child_tid
)
1518 put_user(current
->pid
, current
->set_child_tid
);
1522 * context_switch - switch to the new MM and the new
1523 * thread's register state.
1526 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1528 struct mm_struct
*mm
= next
->mm
;
1529 struct mm_struct
*oldmm
= prev
->active_mm
;
1531 if (unlikely(!mm
)) {
1532 next
->active_mm
= oldmm
;
1533 atomic_inc(&oldmm
->mm_count
);
1534 enter_lazy_tlb(oldmm
, next
);
1536 switch_mm(oldmm
, mm
, next
);
1538 if (unlikely(!prev
->mm
)) {
1539 prev
->active_mm
= NULL
;
1540 WARN_ON(rq
->prev_mm
);
1541 rq
->prev_mm
= oldmm
;
1544 /* Here we just switch the register state and the stack. */
1545 switch_to(prev
, next
, prev
);
1551 * nr_running, nr_uninterruptible and nr_context_switches:
1553 * externally visible scheduler statistics: current number of runnable
1554 * threads, current number of uninterruptible-sleeping threads, total
1555 * number of context switches performed since bootup.
1557 unsigned long nr_running(void)
1559 unsigned long i
, sum
= 0;
1561 for_each_online_cpu(i
)
1562 sum
+= cpu_rq(i
)->nr_running
;
1567 unsigned long nr_uninterruptible(void)
1569 unsigned long i
, sum
= 0;
1572 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1575 * Since we read the counters lockless, it might be slightly
1576 * inaccurate. Do not allow it to go below zero though:
1578 if (unlikely((long)sum
< 0))
1584 unsigned long long nr_context_switches(void)
1586 unsigned long long i
, sum
= 0;
1589 sum
+= cpu_rq(i
)->nr_switches
;
1594 unsigned long nr_iowait(void)
1596 unsigned long i
, sum
= 0;
1599 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1607 * double_rq_lock - safely lock two runqueues
1609 * Note this does not disable interrupts like task_rq_lock,
1610 * you need to do so manually before calling.
1612 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1613 __acquires(rq1
->lock
)
1614 __acquires(rq2
->lock
)
1617 spin_lock(&rq1
->lock
);
1618 __acquire(rq2
->lock
); /* Fake it out ;) */
1621 spin_lock(&rq1
->lock
);
1622 spin_lock(&rq2
->lock
);
1624 spin_lock(&rq2
->lock
);
1625 spin_lock(&rq1
->lock
);
1631 * double_rq_unlock - safely unlock two runqueues
1633 * Note this does not restore interrupts like task_rq_unlock,
1634 * you need to do so manually after calling.
1636 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1637 __releases(rq1
->lock
)
1638 __releases(rq2
->lock
)
1640 spin_unlock(&rq1
->lock
);
1642 spin_unlock(&rq2
->lock
);
1644 __release(rq2
->lock
);
1648 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1650 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1651 __releases(this_rq
->lock
)
1652 __acquires(busiest
->lock
)
1653 __acquires(this_rq
->lock
)
1655 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1656 if (busiest
< this_rq
) {
1657 spin_unlock(&this_rq
->lock
);
1658 spin_lock(&busiest
->lock
);
1659 spin_lock(&this_rq
->lock
);
1661 spin_lock(&busiest
->lock
);
1666 * If dest_cpu is allowed for this process, migrate the task to it.
1667 * This is accomplished by forcing the cpu_allowed mask to only
1668 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1669 * the cpu_allowed mask is restored.
1671 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1673 migration_req_t req
;
1675 unsigned long flags
;
1677 rq
= task_rq_lock(p
, &flags
);
1678 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1679 || unlikely(cpu_is_offline(dest_cpu
)))
1682 /* force the process onto the specified CPU */
1683 if (migrate_task(p
, dest_cpu
, &req
)) {
1684 /* Need to wait for migration thread (might exit: take ref). */
1685 struct task_struct
*mt
= rq
->migration_thread
;
1686 get_task_struct(mt
);
1687 task_rq_unlock(rq
, &flags
);
1688 wake_up_process(mt
);
1689 put_task_struct(mt
);
1690 wait_for_completion(&req
.done
);
1694 task_rq_unlock(rq
, &flags
);
1698 * sched_exec(): find the highest-level, exec-balance-capable
1699 * domain and try to migrate the task to the least loaded CPU.
1701 * execve() is a valuable balancing opportunity, because at this point
1702 * the task has the smallest effective memory and cache footprint.
1704 void sched_exec(void)
1706 struct sched_domain
*tmp
, *sd
= NULL
;
1707 int new_cpu
, this_cpu
= get_cpu();
1709 for_each_domain(this_cpu
, tmp
)
1710 if (tmp
->flags
& SD_BALANCE_EXEC
)
1714 struct sched_group
*group
;
1715 schedstat_inc(sd
, sbe_cnt
);
1716 group
= find_idlest_group(sd
, current
, this_cpu
);
1718 schedstat_inc(sd
, sbe_balanced
);
1721 new_cpu
= find_idlest_cpu(group
, this_cpu
);
1722 if (new_cpu
== -1 || new_cpu
== this_cpu
) {
1723 schedstat_inc(sd
, sbe_balanced
);
1727 schedstat_inc(sd
, sbe_pushed
);
1729 sched_migrate_task(current
, new_cpu
);
1737 * pull_task - move a task from a remote runqueue to the local runqueue.
1738 * Both runqueues must be locked.
1741 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1742 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1744 dequeue_task(p
, src_array
);
1745 src_rq
->nr_running
--;
1746 set_task_cpu(p
, this_cpu
);
1747 this_rq
->nr_running
++;
1748 enqueue_task(p
, this_array
);
1749 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1750 + this_rq
->timestamp_last_tick
;
1752 * Note that idle threads have a prio of MAX_PRIO, for this test
1753 * to be always true for them.
1755 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1756 resched_task(this_rq
->curr
);
1760 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1763 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1764 struct sched_domain
*sd
, enum idle_type idle
, int *all_pinned
)
1767 * We do not migrate tasks that are:
1768 * 1) running (obviously), or
1769 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1770 * 3) are cache-hot on their current CPU.
1772 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1776 if (task_running(rq
, p
))
1780 * Aggressive migration if:
1781 * 1) task is cache cold, or
1782 * 2) too many balance attempts have failed.
1785 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1788 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1794 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1795 * as part of a balancing operation within "domain". Returns the number of
1798 * Called with both runqueues locked.
1800 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1801 unsigned long max_nr_move
, struct sched_domain
*sd
,
1802 enum idle_type idle
, int *all_pinned
)
1804 prio_array_t
*array
, *dst_array
;
1805 struct list_head
*head
, *curr
;
1806 int idx
, pulled
= 0, pinned
= 0;
1809 if (max_nr_move
== 0)
1815 * We first consider expired tasks. Those will likely not be
1816 * executed in the near future, and they are most likely to
1817 * be cache-cold, thus switching CPUs has the least effect
1820 if (busiest
->expired
->nr_active
) {
1821 array
= busiest
->expired
;
1822 dst_array
= this_rq
->expired
;
1824 array
= busiest
->active
;
1825 dst_array
= this_rq
->active
;
1829 /* Start searching at priority 0: */
1833 idx
= sched_find_first_bit(array
->bitmap
);
1835 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1836 if (idx
>= MAX_PRIO
) {
1837 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1838 array
= busiest
->active
;
1839 dst_array
= this_rq
->active
;
1845 head
= array
->queue
+ idx
;
1848 tmp
= list_entry(curr
, task_t
, run_list
);
1852 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1859 #ifdef CONFIG_SCHEDSTATS
1860 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1861 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1864 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1867 /* We only want to steal up to the prescribed number of tasks. */
1868 if (pulled
< max_nr_move
) {
1876 * Right now, this is the only place pull_task() is called,
1877 * so we can safely collect pull_task() stats here rather than
1878 * inside pull_task().
1880 schedstat_add(sd
, lb_gained
[idle
], pulled
);
1883 *all_pinned
= pinned
;
1888 * find_busiest_group finds and returns the busiest CPU group within the
1889 * domain. It calculates and returns the number of tasks which should be
1890 * moved to restore balance via the imbalance parameter.
1892 static struct sched_group
*
1893 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
1894 unsigned long *imbalance
, enum idle_type idle
)
1896 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1897 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
1900 max_load
= this_load
= total_load
= total_pwr
= 0;
1901 if (idle
== NOT_IDLE
)
1902 load_idx
= sd
->busy_idx
;
1903 else if (idle
== NEWLY_IDLE
)
1904 load_idx
= sd
->newidle_idx
;
1906 load_idx
= sd
->idle_idx
;
1913 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1915 /* Tally up the load of all CPUs in the group */
1918 for_each_cpu_mask(i
, group
->cpumask
) {
1919 /* Bias balancing toward cpus of our domain */
1921 load
= target_load(i
, load_idx
);
1923 load
= source_load(i
, load_idx
);
1928 total_load
+= avg_load
;
1929 total_pwr
+= group
->cpu_power
;
1931 /* Adjust by relative CPU power of the group */
1932 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1935 this_load
= avg_load
;
1937 } else if (avg_load
> max_load
) {
1938 max_load
= avg_load
;
1941 group
= group
->next
;
1942 } while (group
!= sd
->groups
);
1944 if (!busiest
|| this_load
>= max_load
)
1947 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
1949 if (this_load
>= avg_load
||
1950 100*max_load
<= sd
->imbalance_pct
*this_load
)
1954 * We're trying to get all the cpus to the average_load, so we don't
1955 * want to push ourselves above the average load, nor do we wish to
1956 * reduce the max loaded cpu below the average load, as either of these
1957 * actions would just result in more rebalancing later, and ping-pong
1958 * tasks around. Thus we look for the minimum possible imbalance.
1959 * Negative imbalances (*we* are more loaded than anyone else) will
1960 * be counted as no imbalance for these purposes -- we can't fix that
1961 * by pulling tasks to us. Be careful of negative numbers as they'll
1962 * appear as very large values with unsigned longs.
1964 /* How much load to actually move to equalise the imbalance */
1965 *imbalance
= min((max_load
- avg_load
) * busiest
->cpu_power
,
1966 (avg_load
- this_load
) * this->cpu_power
)
1969 if (*imbalance
< SCHED_LOAD_SCALE
) {
1970 unsigned long pwr_now
= 0, pwr_move
= 0;
1973 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
1979 * OK, we don't have enough imbalance to justify moving tasks,
1980 * however we may be able to increase total CPU power used by
1984 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
1985 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
1986 pwr_now
/= SCHED_LOAD_SCALE
;
1988 /* Amount of load we'd subtract */
1989 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
1991 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
1994 /* Amount of load we'd add */
1995 if (max_load
*busiest
->cpu_power
<
1996 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
1997 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
1999 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
2000 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
2001 pwr_move
/= SCHED_LOAD_SCALE
;
2003 /* Move if we gain throughput */
2004 if (pwr_move
<= pwr_now
)
2011 /* Get rid of the scaling factor, rounding down as we divide */
2012 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
2022 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2024 static runqueue_t
*find_busiest_queue(struct sched_group
*group
)
2026 unsigned long load
, max_load
= 0;
2027 runqueue_t
*busiest
= NULL
;
2030 for_each_cpu_mask(i
, group
->cpumask
) {
2031 load
= source_load(i
, 0);
2033 if (load
> max_load
) {
2035 busiest
= cpu_rq(i
);
2043 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2044 * tasks if there is an imbalance.
2046 * Called with this_rq unlocked.
2048 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
2049 struct sched_domain
*sd
, enum idle_type idle
)
2051 struct sched_group
*group
;
2052 runqueue_t
*busiest
;
2053 unsigned long imbalance
;
2054 int nr_moved
, all_pinned
;
2055 int active_balance
= 0;
2057 spin_lock(&this_rq
->lock
);
2058 schedstat_inc(sd
, lb_cnt
[idle
]);
2060 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
);
2062 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2066 busiest
= find_busiest_queue(group
);
2068 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2072 BUG_ON(busiest
== this_rq
);
2074 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2077 if (busiest
->nr_running
> 1) {
2079 * Attempt to move tasks. If find_busiest_group has found
2080 * an imbalance but busiest->nr_running <= 1, the group is
2081 * still unbalanced. nr_moved simply stays zero, so it is
2082 * correctly treated as an imbalance.
2084 double_lock_balance(this_rq
, busiest
);
2085 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2086 imbalance
, sd
, idle
,
2088 spin_unlock(&busiest
->lock
);
2090 /* All tasks on this runqueue were pinned by CPU affinity */
2091 if (unlikely(all_pinned
))
2095 spin_unlock(&this_rq
->lock
);
2098 schedstat_inc(sd
, lb_failed
[idle
]);
2099 sd
->nr_balance_failed
++;
2101 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2103 spin_lock(&busiest
->lock
);
2104 if (!busiest
->active_balance
) {
2105 busiest
->active_balance
= 1;
2106 busiest
->push_cpu
= this_cpu
;
2109 spin_unlock(&busiest
->lock
);
2111 wake_up_process(busiest
->migration_thread
);
2114 * We've kicked active balancing, reset the failure
2117 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2120 sd
->nr_balance_failed
= 0;
2122 if (likely(!active_balance
)) {
2123 /* We were unbalanced, so reset the balancing interval */
2124 sd
->balance_interval
= sd
->min_interval
;
2127 * If we've begun active balancing, start to back off. This
2128 * case may not be covered by the all_pinned logic if there
2129 * is only 1 task on the busy runqueue (because we don't call
2132 if (sd
->balance_interval
< sd
->max_interval
)
2133 sd
->balance_interval
*= 2;
2139 spin_unlock(&this_rq
->lock
);
2141 schedstat_inc(sd
, lb_balanced
[idle
]);
2143 sd
->nr_balance_failed
= 0;
2144 /* tune up the balancing interval */
2145 if (sd
->balance_interval
< sd
->max_interval
)
2146 sd
->balance_interval
*= 2;
2152 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2153 * tasks if there is an imbalance.
2155 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2156 * this_rq is locked.
2158 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2159 struct sched_domain
*sd
)
2161 struct sched_group
*group
;
2162 runqueue_t
*busiest
= NULL
;
2163 unsigned long imbalance
;
2166 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2167 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
);
2169 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2173 busiest
= find_busiest_queue(group
);
2175 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2179 BUG_ON(busiest
== this_rq
);
2181 /* Attempt to move tasks */
2182 double_lock_balance(this_rq
, busiest
);
2184 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2185 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2186 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2188 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2190 sd
->nr_balance_failed
= 0;
2192 spin_unlock(&busiest
->lock
);
2196 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2197 sd
->nr_balance_failed
= 0;
2202 * idle_balance is called by schedule() if this_cpu is about to become
2203 * idle. Attempts to pull tasks from other CPUs.
2205 static inline void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2207 struct sched_domain
*sd
;
2209 for_each_domain(this_cpu
, sd
) {
2210 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2211 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2212 /* We've pulled tasks over so stop searching */
2220 * active_load_balance is run by migration threads. It pushes running tasks
2221 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2222 * running on each physical CPU where possible, and avoids physical /
2223 * logical imbalances.
2225 * Called with busiest_rq locked.
2227 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2229 struct sched_domain
*sd
;
2230 runqueue_t
*target_rq
;
2231 int target_cpu
= busiest_rq
->push_cpu
;
2233 if (busiest_rq
->nr_running
<= 1)
2234 /* no task to move */
2237 target_rq
= cpu_rq(target_cpu
);
2240 * This condition is "impossible", if it occurs
2241 * we need to fix it. Originally reported by
2242 * Bjorn Helgaas on a 128-cpu setup.
2244 BUG_ON(busiest_rq
== target_rq
);
2246 /* move a task from busiest_rq to target_rq */
2247 double_lock_balance(busiest_rq
, target_rq
);
2249 /* Search for an sd spanning us and the target CPU. */
2250 for_each_domain(target_cpu
, sd
)
2251 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2252 cpu_isset(busiest_cpu
, sd
->span
))
2255 if (unlikely(sd
== NULL
))
2258 schedstat_inc(sd
, alb_cnt
);
2260 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1, sd
, SCHED_IDLE
, NULL
))
2261 schedstat_inc(sd
, alb_pushed
);
2263 schedstat_inc(sd
, alb_failed
);
2265 spin_unlock(&target_rq
->lock
);
2269 * rebalance_tick will get called every timer tick, on every CPU.
2271 * It checks each scheduling domain to see if it is due to be balanced,
2272 * and initiates a balancing operation if so.
2274 * Balancing parameters are set up in arch_init_sched_domains.
2277 /* Don't have all balancing operations going off at once */
2278 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2280 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2281 enum idle_type idle
)
2283 unsigned long old_load
, this_load
;
2284 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2285 struct sched_domain
*sd
;
2288 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2289 /* Update our load */
2290 for (i
= 0; i
< 3; i
++) {
2291 unsigned long new_load
= this_load
;
2293 old_load
= this_rq
->cpu_load
[i
];
2295 * Round up the averaging division if load is increasing. This
2296 * prevents us from getting stuck on 9 if the load is 10, for
2299 if (new_load
> old_load
)
2300 new_load
+= scale
-1;
2301 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2304 for_each_domain(this_cpu
, sd
) {
2305 unsigned long interval
;
2307 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2310 interval
= sd
->balance_interval
;
2311 if (idle
!= SCHED_IDLE
)
2312 interval
*= sd
->busy_factor
;
2314 /* scale ms to jiffies */
2315 interval
= msecs_to_jiffies(interval
);
2316 if (unlikely(!interval
))
2319 if (j
- sd
->last_balance
>= interval
) {
2320 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2321 /* We've pulled tasks over so no longer idle */
2324 sd
->last_balance
+= interval
;
2330 * on UP we do not need to balance between CPUs:
2332 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2335 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2340 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2343 #ifdef CONFIG_SCHED_SMT
2344 spin_lock(&rq
->lock
);
2346 * If an SMT sibling task has been put to sleep for priority
2347 * reasons reschedule the idle task to see if it can now run.
2349 if (rq
->nr_running
) {
2350 resched_task(rq
->idle
);
2353 spin_unlock(&rq
->lock
);
2358 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2360 EXPORT_PER_CPU_SYMBOL(kstat
);
2363 * This is called on clock ticks and on context switches.
2364 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2366 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2367 unsigned long long now
)
2369 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2370 p
->sched_time
+= now
- last
;
2374 * Return current->sched_time plus any more ns on the sched_clock
2375 * that have not yet been banked.
2377 unsigned long long current_sched_time(const task_t
*tsk
)
2379 unsigned long long ns
;
2380 unsigned long flags
;
2381 local_irq_save(flags
);
2382 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2383 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2384 local_irq_restore(flags
);
2389 * We place interactive tasks back into the active array, if possible.
2391 * To guarantee that this does not starve expired tasks we ignore the
2392 * interactivity of a task if the first expired task had to wait more
2393 * than a 'reasonable' amount of time. This deadline timeout is
2394 * load-dependent, as the frequency of array switched decreases with
2395 * increasing number of running tasks. We also ignore the interactivity
2396 * if a better static_prio task has expired:
2398 #define EXPIRED_STARVING(rq) \
2399 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2400 (jiffies - (rq)->expired_timestamp >= \
2401 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2402 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2405 * Account user cpu time to a process.
2406 * @p: the process that the cpu time gets accounted to
2407 * @hardirq_offset: the offset to subtract from hardirq_count()
2408 * @cputime: the cpu time spent in user space since the last update
2410 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2412 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2415 p
->utime
= cputime_add(p
->utime
, cputime
);
2417 /* Add user time to cpustat. */
2418 tmp
= cputime_to_cputime64(cputime
);
2419 if (TASK_NICE(p
) > 0)
2420 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2422 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2426 * Account system cpu time to a process.
2427 * @p: the process that the cpu time gets accounted to
2428 * @hardirq_offset: the offset to subtract from hardirq_count()
2429 * @cputime: the cpu time spent in kernel space since the last update
2431 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2434 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2435 runqueue_t
*rq
= this_rq();
2438 p
->stime
= cputime_add(p
->stime
, cputime
);
2440 /* Add system time to cpustat. */
2441 tmp
= cputime_to_cputime64(cputime
);
2442 if (hardirq_count() - hardirq_offset
)
2443 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2444 else if (softirq_count())
2445 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2446 else if (p
!= rq
->idle
)
2447 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2448 else if (atomic_read(&rq
->nr_iowait
) > 0)
2449 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2451 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2452 /* Account for system time used */
2453 acct_update_integrals(p
);
2454 /* Update rss highwater mark */
2455 update_mem_hiwater(p
);
2459 * Account for involuntary wait time.
2460 * @p: the process from which the cpu time has been stolen
2461 * @steal: the cpu time spent in involuntary wait
2463 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2465 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2466 cputime64_t tmp
= cputime_to_cputime64(steal
);
2467 runqueue_t
*rq
= this_rq();
2469 if (p
== rq
->idle
) {
2470 p
->stime
= cputime_add(p
->stime
, steal
);
2471 if (atomic_read(&rq
->nr_iowait
) > 0)
2472 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2474 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2476 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2480 * This function gets called by the timer code, with HZ frequency.
2481 * We call it with interrupts disabled.
2483 * It also gets called by the fork code, when changing the parent's
2486 void scheduler_tick(void)
2488 int cpu
= smp_processor_id();
2489 runqueue_t
*rq
= this_rq();
2490 task_t
*p
= current
;
2491 unsigned long long now
= sched_clock();
2493 update_cpu_clock(p
, rq
, now
);
2495 rq
->timestamp_last_tick
= now
;
2497 if (p
== rq
->idle
) {
2498 if (wake_priority_sleeper(rq
))
2500 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2504 /* Task might have expired already, but not scheduled off yet */
2505 if (p
->array
!= rq
->active
) {
2506 set_tsk_need_resched(p
);
2509 spin_lock(&rq
->lock
);
2511 * The task was running during this tick - update the
2512 * time slice counter. Note: we do not update a thread's
2513 * priority until it either goes to sleep or uses up its
2514 * timeslice. This makes it possible for interactive tasks
2515 * to use up their timeslices at their highest priority levels.
2519 * RR tasks need a special form of timeslice management.
2520 * FIFO tasks have no timeslices.
2522 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2523 p
->time_slice
= task_timeslice(p
);
2524 p
->first_time_slice
= 0;
2525 set_tsk_need_resched(p
);
2527 /* put it at the end of the queue: */
2528 requeue_task(p
, rq
->active
);
2532 if (!--p
->time_slice
) {
2533 dequeue_task(p
, rq
->active
);
2534 set_tsk_need_resched(p
);
2535 p
->prio
= effective_prio(p
);
2536 p
->time_slice
= task_timeslice(p
);
2537 p
->first_time_slice
= 0;
2539 if (!rq
->expired_timestamp
)
2540 rq
->expired_timestamp
= jiffies
;
2541 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2542 enqueue_task(p
, rq
->expired
);
2543 if (p
->static_prio
< rq
->best_expired_prio
)
2544 rq
->best_expired_prio
= p
->static_prio
;
2546 enqueue_task(p
, rq
->active
);
2549 * Prevent a too long timeslice allowing a task to monopolize
2550 * the CPU. We do this by splitting up the timeslice into
2553 * Note: this does not mean the task's timeslices expire or
2554 * get lost in any way, they just might be preempted by
2555 * another task of equal priority. (one with higher
2556 * priority would have preempted this task already.) We
2557 * requeue this task to the end of the list on this priority
2558 * level, which is in essence a round-robin of tasks with
2561 * This only applies to tasks in the interactive
2562 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2564 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2565 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2566 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2567 (p
->array
== rq
->active
)) {
2569 requeue_task(p
, rq
->active
);
2570 set_tsk_need_resched(p
);
2574 spin_unlock(&rq
->lock
);
2576 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2579 #ifdef CONFIG_SCHED_SMT
2580 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2582 struct sched_domain
*tmp
, *sd
= NULL
;
2583 cpumask_t sibling_map
;
2586 for_each_domain(this_cpu
, tmp
)
2587 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2594 * Unlock the current runqueue because we have to lock in
2595 * CPU order to avoid deadlocks. Caller knows that we might
2596 * unlock. We keep IRQs disabled.
2598 spin_unlock(&this_rq
->lock
);
2600 sibling_map
= sd
->span
;
2602 for_each_cpu_mask(i
, sibling_map
)
2603 spin_lock(&cpu_rq(i
)->lock
);
2605 * We clear this CPU from the mask. This both simplifies the
2606 * inner loop and keps this_rq locked when we exit:
2608 cpu_clear(this_cpu
, sibling_map
);
2610 for_each_cpu_mask(i
, sibling_map
) {
2611 runqueue_t
*smt_rq
= cpu_rq(i
);
2614 * If an SMT sibling task is sleeping due to priority
2615 * reasons wake it up now.
2617 if (smt_rq
->curr
== smt_rq
->idle
&& smt_rq
->nr_running
)
2618 resched_task(smt_rq
->idle
);
2621 for_each_cpu_mask(i
, sibling_map
)
2622 spin_unlock(&cpu_rq(i
)->lock
);
2624 * We exit with this_cpu's rq still held and IRQs
2629 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2631 struct sched_domain
*tmp
, *sd
= NULL
;
2632 cpumask_t sibling_map
;
2633 prio_array_t
*array
;
2637 for_each_domain(this_cpu
, tmp
)
2638 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2645 * The same locking rules and details apply as for
2646 * wake_sleeping_dependent():
2648 spin_unlock(&this_rq
->lock
);
2649 sibling_map
= sd
->span
;
2650 for_each_cpu_mask(i
, sibling_map
)
2651 spin_lock(&cpu_rq(i
)->lock
);
2652 cpu_clear(this_cpu
, sibling_map
);
2655 * Establish next task to be run - it might have gone away because
2656 * we released the runqueue lock above:
2658 if (!this_rq
->nr_running
)
2660 array
= this_rq
->active
;
2661 if (!array
->nr_active
)
2662 array
= this_rq
->expired
;
2663 BUG_ON(!array
->nr_active
);
2665 p
= list_entry(array
->queue
[sched_find_first_bit(array
->bitmap
)].next
,
2668 for_each_cpu_mask(i
, sibling_map
) {
2669 runqueue_t
*smt_rq
= cpu_rq(i
);
2670 task_t
*smt_curr
= smt_rq
->curr
;
2673 * If a user task with lower static priority than the
2674 * running task on the SMT sibling is trying to schedule,
2675 * delay it till there is proportionately less timeslice
2676 * left of the sibling task to prevent a lower priority
2677 * task from using an unfair proportion of the
2678 * physical cpu's resources. -ck
2680 if (((smt_curr
->time_slice
* (100 - sd
->per_cpu_gain
) / 100) >
2681 task_timeslice(p
) || rt_task(smt_curr
)) &&
2682 p
->mm
&& smt_curr
->mm
&& !rt_task(p
))
2686 * Reschedule a lower priority task on the SMT sibling,
2687 * or wake it up if it has been put to sleep for priority
2690 if ((((p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100) >
2691 task_timeslice(smt_curr
) || rt_task(p
)) &&
2692 smt_curr
->mm
&& p
->mm
&& !rt_task(smt_curr
)) ||
2693 (smt_curr
== smt_rq
->idle
&& smt_rq
->nr_running
))
2694 resched_task(smt_curr
);
2697 for_each_cpu_mask(i
, sibling_map
)
2698 spin_unlock(&cpu_rq(i
)->lock
);
2702 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2706 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2712 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2714 void fastcall
add_preempt_count(int val
)
2719 BUG_ON((preempt_count() < 0));
2720 preempt_count() += val
;
2722 * Spinlock count overflowing soon?
2724 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2726 EXPORT_SYMBOL(add_preempt_count
);
2728 void fastcall
sub_preempt_count(int val
)
2733 BUG_ON(val
> preempt_count());
2735 * Is the spinlock portion underflowing?
2737 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2738 preempt_count() -= val
;
2740 EXPORT_SYMBOL(sub_preempt_count
);
2745 * schedule() is the main scheduler function.
2747 asmlinkage
void __sched
schedule(void)
2750 task_t
*prev
, *next
;
2752 prio_array_t
*array
;
2753 struct list_head
*queue
;
2754 unsigned long long now
;
2755 unsigned long run_time
;
2759 * Test if we are atomic. Since do_exit() needs to call into
2760 * schedule() atomically, we ignore that path for now.
2761 * Otherwise, whine if we are scheduling when we should not be.
2763 if (likely(!current
->exit_state
)) {
2764 if (unlikely(in_atomic())) {
2765 printk(KERN_ERR
"scheduling while atomic: "
2767 current
->comm
, preempt_count(), current
->pid
);
2771 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2776 release_kernel_lock(prev
);
2777 need_resched_nonpreemptible
:
2781 * The idle thread is not allowed to schedule!
2782 * Remove this check after it has been exercised a bit.
2784 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2785 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
2789 schedstat_inc(rq
, sched_cnt
);
2790 now
= sched_clock();
2791 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
2792 run_time
= now
- prev
->timestamp
;
2793 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
2796 run_time
= NS_MAX_SLEEP_AVG
;
2799 * Tasks charged proportionately less run_time at high sleep_avg to
2800 * delay them losing their interactive status
2802 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
2804 spin_lock_irq(&rq
->lock
);
2806 if (unlikely(prev
->flags
& PF_DEAD
))
2807 prev
->state
= EXIT_DEAD
;
2809 switch_count
= &prev
->nivcsw
;
2810 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2811 switch_count
= &prev
->nvcsw
;
2812 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
2813 unlikely(signal_pending(prev
))))
2814 prev
->state
= TASK_RUNNING
;
2816 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
2817 rq
->nr_uninterruptible
++;
2818 deactivate_task(prev
, rq
);
2822 cpu
= smp_processor_id();
2823 if (unlikely(!rq
->nr_running
)) {
2825 idle_balance(cpu
, rq
);
2826 if (!rq
->nr_running
) {
2828 rq
->expired_timestamp
= 0;
2829 wake_sleeping_dependent(cpu
, rq
);
2831 * wake_sleeping_dependent() might have released
2832 * the runqueue, so break out if we got new
2835 if (!rq
->nr_running
)
2839 if (dependent_sleeper(cpu
, rq
)) {
2844 * dependent_sleeper() releases and reacquires the runqueue
2845 * lock, hence go into the idle loop if the rq went
2848 if (unlikely(!rq
->nr_running
))
2853 if (unlikely(!array
->nr_active
)) {
2855 * Switch the active and expired arrays.
2857 schedstat_inc(rq
, sched_switch
);
2858 rq
->active
= rq
->expired
;
2859 rq
->expired
= array
;
2861 rq
->expired_timestamp
= 0;
2862 rq
->best_expired_prio
= MAX_PRIO
;
2865 idx
= sched_find_first_bit(array
->bitmap
);
2866 queue
= array
->queue
+ idx
;
2867 next
= list_entry(queue
->next
, task_t
, run_list
);
2869 if (!rt_task(next
) && next
->activated
> 0) {
2870 unsigned long long delta
= now
- next
->timestamp
;
2871 if (unlikely((long long)(now
- next
->timestamp
) < 0))
2874 if (next
->activated
== 1)
2875 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
2877 array
= next
->array
;
2878 dequeue_task(next
, array
);
2879 recalc_task_prio(next
, next
->timestamp
+ delta
);
2880 enqueue_task(next
, array
);
2882 next
->activated
= 0;
2884 if (next
== rq
->idle
)
2885 schedstat_inc(rq
, sched_goidle
);
2887 clear_tsk_need_resched(prev
);
2888 rcu_qsctr_inc(task_cpu(prev
));
2890 update_cpu_clock(prev
, rq
, now
);
2892 prev
->sleep_avg
-= run_time
;
2893 if ((long)prev
->sleep_avg
<= 0)
2894 prev
->sleep_avg
= 0;
2895 prev
->timestamp
= prev
->last_ran
= now
;
2897 sched_info_switch(prev
, next
);
2898 if (likely(prev
!= next
)) {
2899 next
->timestamp
= now
;
2904 prepare_task_switch(rq
, next
);
2905 prev
= context_switch(rq
, prev
, next
);
2908 * this_rq must be evaluated again because prev may have moved
2909 * CPUs since it called schedule(), thus the 'rq' on its stack
2910 * frame will be invalid.
2912 finish_task_switch(this_rq(), prev
);
2914 spin_unlock_irq(&rq
->lock
);
2917 if (unlikely(reacquire_kernel_lock(prev
) < 0))
2918 goto need_resched_nonpreemptible
;
2919 preempt_enable_no_resched();
2920 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
2924 EXPORT_SYMBOL(schedule
);
2926 #ifdef CONFIG_PREEMPT
2928 * this is is the entry point to schedule() from in-kernel preemption
2929 * off of preempt_enable. Kernel preemptions off return from interrupt
2930 * occur there and call schedule directly.
2932 asmlinkage
void __sched
preempt_schedule(void)
2934 struct thread_info
*ti
= current_thread_info();
2935 #ifdef CONFIG_PREEMPT_BKL
2936 struct task_struct
*task
= current
;
2937 int saved_lock_depth
;
2940 * If there is a non-zero preempt_count or interrupts are disabled,
2941 * we do not want to preempt the current task. Just return..
2943 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
2947 add_preempt_count(PREEMPT_ACTIVE
);
2949 * We keep the big kernel semaphore locked, but we
2950 * clear ->lock_depth so that schedule() doesnt
2951 * auto-release the semaphore:
2953 #ifdef CONFIG_PREEMPT_BKL
2954 saved_lock_depth
= task
->lock_depth
;
2955 task
->lock_depth
= -1;
2958 #ifdef CONFIG_PREEMPT_BKL
2959 task
->lock_depth
= saved_lock_depth
;
2961 sub_preempt_count(PREEMPT_ACTIVE
);
2963 /* we could miss a preemption opportunity between schedule and now */
2965 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
2969 EXPORT_SYMBOL(preempt_schedule
);
2972 * this is is the entry point to schedule() from kernel preemption
2973 * off of irq context.
2974 * Note, that this is called and return with irqs disabled. This will
2975 * protect us against recursive calling from irq.
2977 asmlinkage
void __sched
preempt_schedule_irq(void)
2979 struct thread_info
*ti
= current_thread_info();
2980 #ifdef CONFIG_PREEMPT_BKL
2981 struct task_struct
*task
= current
;
2982 int saved_lock_depth
;
2984 /* Catch callers which need to be fixed*/
2985 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
2988 add_preempt_count(PREEMPT_ACTIVE
);
2990 * We keep the big kernel semaphore locked, but we
2991 * clear ->lock_depth so that schedule() doesnt
2992 * auto-release the semaphore:
2994 #ifdef CONFIG_PREEMPT_BKL
2995 saved_lock_depth
= task
->lock_depth
;
2996 task
->lock_depth
= -1;
3000 local_irq_disable();
3001 #ifdef CONFIG_PREEMPT_BKL
3002 task
->lock_depth
= saved_lock_depth
;
3004 sub_preempt_count(PREEMPT_ACTIVE
);
3006 /* we could miss a preemption opportunity between schedule and now */
3008 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3012 #endif /* CONFIG_PREEMPT */
3014 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
, void *key
)
3016 task_t
*p
= curr
->private;
3017 return try_to_wake_up(p
, mode
, sync
);
3020 EXPORT_SYMBOL(default_wake_function
);
3023 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3024 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3025 * number) then we wake all the non-exclusive tasks and one exclusive task.
3027 * There are circumstances in which we can try to wake a task which has already
3028 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3029 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3031 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3032 int nr_exclusive
, int sync
, void *key
)
3034 struct list_head
*tmp
, *next
;
3036 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3039 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3040 flags
= curr
->flags
;
3041 if (curr
->func(curr
, mode
, sync
, key
) &&
3042 (flags
& WQ_FLAG_EXCLUSIVE
) &&
3049 * __wake_up - wake up threads blocked on a waitqueue.
3051 * @mode: which threads
3052 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3053 * @key: is directly passed to the wakeup function
3055 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3056 int nr_exclusive
, void *key
)
3058 unsigned long flags
;
3060 spin_lock_irqsave(&q
->lock
, flags
);
3061 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3062 spin_unlock_irqrestore(&q
->lock
, flags
);
3065 EXPORT_SYMBOL(__wake_up
);
3068 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3070 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3072 __wake_up_common(q
, mode
, 1, 0, NULL
);
3076 * __wake_up_sync - wake up threads blocked on a waitqueue.
3078 * @mode: which threads
3079 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3081 * The sync wakeup differs that the waker knows that it will schedule
3082 * away soon, so while the target thread will be woken up, it will not
3083 * be migrated to another CPU - ie. the two threads are 'synchronized'
3084 * with each other. This can prevent needless bouncing between CPUs.
3086 * On UP it can prevent extra preemption.
3088 void fastcall
__wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3090 unsigned long flags
;
3096 if (unlikely(!nr_exclusive
))
3099 spin_lock_irqsave(&q
->lock
, flags
);
3100 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3101 spin_unlock_irqrestore(&q
->lock
, flags
);
3103 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3105 void fastcall
complete(struct completion
*x
)
3107 unsigned long flags
;
3109 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3111 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3113 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3115 EXPORT_SYMBOL(complete
);
3117 void fastcall
complete_all(struct completion
*x
)
3119 unsigned long flags
;
3121 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3122 x
->done
+= UINT_MAX
/2;
3123 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3125 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3127 EXPORT_SYMBOL(complete_all
);
3129 void fastcall __sched
wait_for_completion(struct completion
*x
)
3132 spin_lock_irq(&x
->wait
.lock
);
3134 DECLARE_WAITQUEUE(wait
, current
);
3136 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3137 __add_wait_queue_tail(&x
->wait
, &wait
);
3139 __set_current_state(TASK_UNINTERRUPTIBLE
);
3140 spin_unlock_irq(&x
->wait
.lock
);
3142 spin_lock_irq(&x
->wait
.lock
);
3144 __remove_wait_queue(&x
->wait
, &wait
);
3147 spin_unlock_irq(&x
->wait
.lock
);
3149 EXPORT_SYMBOL(wait_for_completion
);
3151 unsigned long fastcall __sched
3152 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3156 spin_lock_irq(&x
->wait
.lock
);
3158 DECLARE_WAITQUEUE(wait
, current
);
3160 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3161 __add_wait_queue_tail(&x
->wait
, &wait
);
3163 __set_current_state(TASK_UNINTERRUPTIBLE
);
3164 spin_unlock_irq(&x
->wait
.lock
);
3165 timeout
= schedule_timeout(timeout
);
3166 spin_lock_irq(&x
->wait
.lock
);
3168 __remove_wait_queue(&x
->wait
, &wait
);
3172 __remove_wait_queue(&x
->wait
, &wait
);
3176 spin_unlock_irq(&x
->wait
.lock
);
3179 EXPORT_SYMBOL(wait_for_completion_timeout
);
3181 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3187 spin_lock_irq(&x
->wait
.lock
);
3189 DECLARE_WAITQUEUE(wait
, current
);
3191 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3192 __add_wait_queue_tail(&x
->wait
, &wait
);
3194 if (signal_pending(current
)) {
3196 __remove_wait_queue(&x
->wait
, &wait
);
3199 __set_current_state(TASK_INTERRUPTIBLE
);
3200 spin_unlock_irq(&x
->wait
.lock
);
3202 spin_lock_irq(&x
->wait
.lock
);
3204 __remove_wait_queue(&x
->wait
, &wait
);
3208 spin_unlock_irq(&x
->wait
.lock
);
3212 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3214 unsigned long fastcall __sched
3215 wait_for_completion_interruptible_timeout(struct completion
*x
,
3216 unsigned long timeout
)
3220 spin_lock_irq(&x
->wait
.lock
);
3222 DECLARE_WAITQUEUE(wait
, current
);
3224 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3225 __add_wait_queue_tail(&x
->wait
, &wait
);
3227 if (signal_pending(current
)) {
3228 timeout
= -ERESTARTSYS
;
3229 __remove_wait_queue(&x
->wait
, &wait
);
3232 __set_current_state(TASK_INTERRUPTIBLE
);
3233 spin_unlock_irq(&x
->wait
.lock
);
3234 timeout
= schedule_timeout(timeout
);
3235 spin_lock_irq(&x
->wait
.lock
);
3237 __remove_wait_queue(&x
->wait
, &wait
);
3241 __remove_wait_queue(&x
->wait
, &wait
);
3245 spin_unlock_irq(&x
->wait
.lock
);
3248 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3251 #define SLEEP_ON_VAR \
3252 unsigned long flags; \
3253 wait_queue_t wait; \
3254 init_waitqueue_entry(&wait, current);
3256 #define SLEEP_ON_HEAD \
3257 spin_lock_irqsave(&q->lock,flags); \
3258 __add_wait_queue(q, &wait); \
3259 spin_unlock(&q->lock);
3261 #define SLEEP_ON_TAIL \
3262 spin_lock_irq(&q->lock); \
3263 __remove_wait_queue(q, &wait); \
3264 spin_unlock_irqrestore(&q->lock, flags);
3266 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3270 current
->state
= TASK_INTERRUPTIBLE
;
3277 EXPORT_SYMBOL(interruptible_sleep_on
);
3279 long fastcall __sched
interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3283 current
->state
= TASK_INTERRUPTIBLE
;
3286 timeout
= schedule_timeout(timeout
);
3292 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3294 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3298 current
->state
= TASK_UNINTERRUPTIBLE
;
3305 EXPORT_SYMBOL(sleep_on
);
3307 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3311 current
->state
= TASK_UNINTERRUPTIBLE
;
3314 timeout
= schedule_timeout(timeout
);
3320 EXPORT_SYMBOL(sleep_on_timeout
);
3322 void set_user_nice(task_t
*p
, long nice
)
3324 unsigned long flags
;
3325 prio_array_t
*array
;
3327 int old_prio
, new_prio
, delta
;
3329 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3332 * We have to be careful, if called from sys_setpriority(),
3333 * the task might be in the middle of scheduling on another CPU.
3335 rq
= task_rq_lock(p
, &flags
);
3337 * The RT priorities are set via sched_setscheduler(), but we still
3338 * allow the 'normal' nice value to be set - but as expected
3339 * it wont have any effect on scheduling until the task is
3343 p
->static_prio
= NICE_TO_PRIO(nice
);
3348 dequeue_task(p
, array
);
3351 new_prio
= NICE_TO_PRIO(nice
);
3352 delta
= new_prio
- old_prio
;
3353 p
->static_prio
= NICE_TO_PRIO(nice
);
3357 enqueue_task(p
, array
);
3359 * If the task increased its priority or is running and
3360 * lowered its priority, then reschedule its CPU:
3362 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3363 resched_task(rq
->curr
);
3366 task_rq_unlock(rq
, &flags
);
3369 EXPORT_SYMBOL(set_user_nice
);
3372 * can_nice - check if a task can reduce its nice value
3376 int can_nice(const task_t
*p
, const int nice
)
3378 /* convert nice value [19,-20] to rlimit style value [0,39] */
3379 int nice_rlim
= 19 - nice
;
3380 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3381 capable(CAP_SYS_NICE
));
3384 #ifdef __ARCH_WANT_SYS_NICE
3387 * sys_nice - change the priority of the current process.
3388 * @increment: priority increment
3390 * sys_setpriority is a more generic, but much slower function that
3391 * does similar things.
3393 asmlinkage
long sys_nice(int increment
)
3399 * Setpriority might change our priority at the same moment.
3400 * We don't have to worry. Conceptually one call occurs first
3401 * and we have a single winner.
3403 if (increment
< -40)
3408 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3414 if (increment
< 0 && !can_nice(current
, nice
))
3417 retval
= security_task_setnice(current
, nice
);
3421 set_user_nice(current
, nice
);
3428 * task_prio - return the priority value of a given task.
3429 * @p: the task in question.
3431 * This is the priority value as seen by users in /proc.
3432 * RT tasks are offset by -200. Normal tasks are centered
3433 * around 0, value goes from -16 to +15.
3435 int task_prio(const task_t
*p
)
3437 return p
->prio
- MAX_RT_PRIO
;
3441 * task_nice - return the nice value of a given task.
3442 * @p: the task in question.
3444 int task_nice(const task_t
*p
)
3446 return TASK_NICE(p
);
3450 * The only users of task_nice are binfmt_elf and binfmt_elf32.
3451 * binfmt_elf is no longer modular, but binfmt_elf32 still is.
3452 * Therefore, task_nice is needed if there is a compat_mode.
3454 #ifdef CONFIG_COMPAT
3455 EXPORT_SYMBOL_GPL(task_nice
);
3459 * idle_cpu - is a given cpu idle currently?
3460 * @cpu: the processor in question.
3462 int idle_cpu(int cpu
)
3464 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3467 EXPORT_SYMBOL_GPL(idle_cpu
);
3470 * idle_task - return the idle task for a given cpu.
3471 * @cpu: the processor in question.
3473 task_t
*idle_task(int cpu
)
3475 return cpu_rq(cpu
)->idle
;
3479 * find_process_by_pid - find a process with a matching PID value.
3480 * @pid: the pid in question.
3482 static inline task_t
*find_process_by_pid(pid_t pid
)
3484 return pid
? find_task_by_pid(pid
) : current
;
3487 /* Actually do priority change: must hold rq lock. */
3488 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3492 p
->rt_priority
= prio
;
3493 if (policy
!= SCHED_NORMAL
)
3494 p
->prio
= MAX_USER_RT_PRIO
-1 - p
->rt_priority
;
3496 p
->prio
= p
->static_prio
;
3500 * sched_setscheduler - change the scheduling policy and/or RT priority of
3502 * @p: the task in question.
3503 * @policy: new policy.
3504 * @param: structure containing the new RT priority.
3506 int sched_setscheduler(struct task_struct
*p
, int policy
, struct sched_param
*param
)
3509 int oldprio
, oldpolicy
= -1;
3510 prio_array_t
*array
;
3511 unsigned long flags
;
3515 /* double check policy once rq lock held */
3517 policy
= oldpolicy
= p
->policy
;
3518 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3519 policy
!= SCHED_NORMAL
)
3522 * Valid priorities for SCHED_FIFO and SCHED_RR are
3523 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3525 if (param
->sched_priority
< 0 ||
3526 param
->sched_priority
> MAX_USER_RT_PRIO
-1)
3528 if ((policy
== SCHED_NORMAL
) != (param
->sched_priority
== 0))
3531 if ((policy
== SCHED_FIFO
|| policy
== SCHED_RR
) &&
3532 param
->sched_priority
> p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
&&
3533 !capable(CAP_SYS_NICE
))
3535 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3536 !capable(CAP_SYS_NICE
))
3539 retval
= security_task_setscheduler(p
, policy
, param
);
3543 * To be able to change p->policy safely, the apropriate
3544 * runqueue lock must be held.
3546 rq
= task_rq_lock(p
, &flags
);
3547 /* recheck policy now with rq lock held */
3548 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3549 policy
= oldpolicy
= -1;
3550 task_rq_unlock(rq
, &flags
);
3555 deactivate_task(p
, rq
);
3557 __setscheduler(p
, policy
, param
->sched_priority
);
3559 __activate_task(p
, rq
);
3561 * Reschedule if we are currently running on this runqueue and
3562 * our priority decreased, or if we are not currently running on
3563 * this runqueue and our priority is higher than the current's
3565 if (task_running(rq
, p
)) {
3566 if (p
->prio
> oldprio
)
3567 resched_task(rq
->curr
);
3568 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3569 resched_task(rq
->curr
);
3571 task_rq_unlock(rq
, &flags
);
3574 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3576 static int do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3579 struct sched_param lparam
;
3580 struct task_struct
*p
;
3582 if (!param
|| pid
< 0)
3584 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3586 read_lock_irq(&tasklist_lock
);
3587 p
= find_process_by_pid(pid
);
3589 read_unlock_irq(&tasklist_lock
);
3592 retval
= sched_setscheduler(p
, policy
, &lparam
);
3593 read_unlock_irq(&tasklist_lock
);
3598 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3599 * @pid: the pid in question.
3600 * @policy: new policy.
3601 * @param: structure containing the new RT priority.
3603 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3604 struct sched_param __user
*param
)
3606 return do_sched_setscheduler(pid
, policy
, param
);
3610 * sys_sched_setparam - set/change the RT priority of a thread
3611 * @pid: the pid in question.
3612 * @param: structure containing the new RT priority.
3614 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3616 return do_sched_setscheduler(pid
, -1, param
);
3620 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3621 * @pid: the pid in question.
3623 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3625 int retval
= -EINVAL
;
3632 read_lock(&tasklist_lock
);
3633 p
= find_process_by_pid(pid
);
3635 retval
= security_task_getscheduler(p
);
3639 read_unlock(&tasklist_lock
);
3646 * sys_sched_getscheduler - get the RT priority of a thread
3647 * @pid: the pid in question.
3648 * @param: structure containing the RT priority.
3650 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3652 struct sched_param lp
;
3653 int retval
= -EINVAL
;
3656 if (!param
|| pid
< 0)
3659 read_lock(&tasklist_lock
);
3660 p
= find_process_by_pid(pid
);
3665 retval
= security_task_getscheduler(p
);
3669 lp
.sched_priority
= p
->rt_priority
;
3670 read_unlock(&tasklist_lock
);
3673 * This one might sleep, we cannot do it with a spinlock held ...
3675 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3681 read_unlock(&tasklist_lock
);
3685 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3689 cpumask_t cpus_allowed
;
3692 read_lock(&tasklist_lock
);
3694 p
= find_process_by_pid(pid
);
3696 read_unlock(&tasklist_lock
);
3697 unlock_cpu_hotplug();
3702 * It is not safe to call set_cpus_allowed with the
3703 * tasklist_lock held. We will bump the task_struct's
3704 * usage count and then drop tasklist_lock.
3707 read_unlock(&tasklist_lock
);
3710 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3711 !capable(CAP_SYS_NICE
))
3714 cpus_allowed
= cpuset_cpus_allowed(p
);
3715 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3716 retval
= set_cpus_allowed(p
, new_mask
);
3720 unlock_cpu_hotplug();
3724 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3725 cpumask_t
*new_mask
)
3727 if (len
< sizeof(cpumask_t
)) {
3728 memset(new_mask
, 0, sizeof(cpumask_t
));
3729 } else if (len
> sizeof(cpumask_t
)) {
3730 len
= sizeof(cpumask_t
);
3732 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3736 * sys_sched_setaffinity - set the cpu affinity of a process
3737 * @pid: pid of the process
3738 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3739 * @user_mask_ptr: user-space pointer to the new cpu mask
3741 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3742 unsigned long __user
*user_mask_ptr
)
3747 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3751 return sched_setaffinity(pid
, new_mask
);
3755 * Represents all cpu's present in the system
3756 * In systems capable of hotplug, this map could dynamically grow
3757 * as new cpu's are detected in the system via any platform specific
3758 * method, such as ACPI for e.g.
3761 cpumask_t cpu_present_map
;
3762 EXPORT_SYMBOL(cpu_present_map
);
3765 cpumask_t cpu_online_map
= CPU_MASK_ALL
;
3766 cpumask_t cpu_possible_map
= CPU_MASK_ALL
;
3769 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
3775 read_lock(&tasklist_lock
);
3778 p
= find_process_by_pid(pid
);
3783 cpus_and(*mask
, p
->cpus_allowed
, cpu_possible_map
);
3786 read_unlock(&tasklist_lock
);
3787 unlock_cpu_hotplug();
3795 * sys_sched_getaffinity - get the cpu affinity of a process
3796 * @pid: pid of the process
3797 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3798 * @user_mask_ptr: user-space pointer to hold the current cpu mask
3800 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
3801 unsigned long __user
*user_mask_ptr
)
3806 if (len
< sizeof(cpumask_t
))
3809 ret
= sched_getaffinity(pid
, &mask
);
3813 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
3816 return sizeof(cpumask_t
);
3820 * sys_sched_yield - yield the current processor to other threads.
3822 * this function yields the current CPU by moving the calling thread
3823 * to the expired array. If there are no other threads running on this
3824 * CPU then this function will return.
3826 asmlinkage
long sys_sched_yield(void)
3828 runqueue_t
*rq
= this_rq_lock();
3829 prio_array_t
*array
= current
->array
;
3830 prio_array_t
*target
= rq
->expired
;
3832 schedstat_inc(rq
, yld_cnt
);
3834 * We implement yielding by moving the task into the expired
3837 * (special rule: RT tasks will just roundrobin in the active
3840 if (rt_task(current
))
3841 target
= rq
->active
;
3843 if (current
->array
->nr_active
== 1) {
3844 schedstat_inc(rq
, yld_act_empty
);
3845 if (!rq
->expired
->nr_active
)
3846 schedstat_inc(rq
, yld_both_empty
);
3847 } else if (!rq
->expired
->nr_active
)
3848 schedstat_inc(rq
, yld_exp_empty
);
3850 if (array
!= target
) {
3851 dequeue_task(current
, array
);
3852 enqueue_task(current
, target
);
3855 * requeue_task is cheaper so perform that if possible.
3857 requeue_task(current
, array
);
3860 * Since we are going to call schedule() anyway, there's
3861 * no need to preempt or enable interrupts:
3863 __release(rq
->lock
);
3864 _raw_spin_unlock(&rq
->lock
);
3865 preempt_enable_no_resched();
3872 static inline void __cond_resched(void)
3875 add_preempt_count(PREEMPT_ACTIVE
);
3877 sub_preempt_count(PREEMPT_ACTIVE
);
3878 } while (need_resched());
3881 int __sched
cond_resched(void)
3883 if (need_resched()) {
3890 EXPORT_SYMBOL(cond_resched
);
3893 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
3894 * call schedule, and on return reacquire the lock.
3896 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
3897 * operations here to prevent schedule() from being called twice (once via
3898 * spin_unlock(), once by hand).
3900 int cond_resched_lock(spinlock_t
* lock
)
3904 if (need_lockbreak(lock
)) {
3910 if (need_resched()) {
3911 _raw_spin_unlock(lock
);
3912 preempt_enable_no_resched();
3920 EXPORT_SYMBOL(cond_resched_lock
);
3922 int __sched
cond_resched_softirq(void)
3924 BUG_ON(!in_softirq());
3926 if (need_resched()) {
3927 __local_bh_enable();
3935 EXPORT_SYMBOL(cond_resched_softirq
);
3939 * yield - yield the current processor to other threads.
3941 * this is a shortcut for kernel-space yielding - it marks the
3942 * thread runnable and calls sys_sched_yield().
3944 void __sched
yield(void)
3946 set_current_state(TASK_RUNNING
);
3950 EXPORT_SYMBOL(yield
);
3953 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
3954 * that process accounting knows that this is a task in IO wait state.
3956 * But don't do that if it is a deliberate, throttling IO wait (this task
3957 * has set its backing_dev_info: the queue against which it should throttle)
3959 void __sched
io_schedule(void)
3961 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
3963 atomic_inc(&rq
->nr_iowait
);
3965 atomic_dec(&rq
->nr_iowait
);
3968 EXPORT_SYMBOL(io_schedule
);
3970 long __sched
io_schedule_timeout(long timeout
)
3972 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
3975 atomic_inc(&rq
->nr_iowait
);
3976 ret
= schedule_timeout(timeout
);
3977 atomic_dec(&rq
->nr_iowait
);
3982 * sys_sched_get_priority_max - return maximum RT priority.
3983 * @policy: scheduling class.
3985 * this syscall returns the maximum rt_priority that can be used
3986 * by a given scheduling class.
3988 asmlinkage
long sys_sched_get_priority_max(int policy
)
3995 ret
= MAX_USER_RT_PRIO
-1;
4005 * sys_sched_get_priority_min - return minimum RT priority.
4006 * @policy: scheduling class.
4008 * this syscall returns the minimum rt_priority that can be used
4009 * by a given scheduling class.
4011 asmlinkage
long sys_sched_get_priority_min(int policy
)
4027 * sys_sched_rr_get_interval - return the default timeslice of a process.
4028 * @pid: pid of the process.
4029 * @interval: userspace pointer to the timeslice value.
4031 * this syscall writes the default timeslice value of a given process
4032 * into the user-space timespec buffer. A value of '0' means infinity.
4035 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4037 int retval
= -EINVAL
;
4045 read_lock(&tasklist_lock
);
4046 p
= find_process_by_pid(pid
);
4050 retval
= security_task_getscheduler(p
);
4054 jiffies_to_timespec(p
->policy
& SCHED_FIFO
?
4055 0 : task_timeslice(p
), &t
);
4056 read_unlock(&tasklist_lock
);
4057 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4061 read_unlock(&tasklist_lock
);
4065 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4067 if (list_empty(&p
->children
)) return NULL
;
4068 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4071 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4073 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
4074 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4077 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4079 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
4080 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4083 static void show_task(task_t
* p
)
4087 unsigned long free
= 0;
4088 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
4090 printk("%-13.13s ", p
->comm
);
4091 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4092 if (state
< ARRAY_SIZE(stat_nam
))
4093 printk(stat_nam
[state
]);
4096 #if (BITS_PER_LONG == 32)
4097 if (state
== TASK_RUNNING
)
4098 printk(" running ");
4100 printk(" %08lX ", thread_saved_pc(p
));
4102 if (state
== TASK_RUNNING
)
4103 printk(" running task ");
4105 printk(" %016lx ", thread_saved_pc(p
));
4107 #ifdef CONFIG_DEBUG_STACK_USAGE
4109 unsigned long * n
= (unsigned long *) (p
->thread_info
+1);
4112 free
= (unsigned long) n
- (unsigned long)(p
->thread_info
+1);
4115 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4116 if ((relative
= eldest_child(p
)))
4117 printk("%5d ", relative
->pid
);
4120 if ((relative
= younger_sibling(p
)))
4121 printk("%7d", relative
->pid
);
4124 if ((relative
= older_sibling(p
)))
4125 printk(" %5d", relative
->pid
);
4129 printk(" (L-TLB)\n");
4131 printk(" (NOTLB)\n");
4133 if (state
!= TASK_RUNNING
)
4134 show_stack(p
, NULL
);
4137 void show_state(void)
4141 #if (BITS_PER_LONG == 32)
4144 printk(" task PC pid father child younger older\n");
4148 printk(" task PC pid father child younger older\n");
4150 read_lock(&tasklist_lock
);
4151 do_each_thread(g
, p
) {
4153 * reset the NMI-timeout, listing all files on a slow
4154 * console might take alot of time:
4156 touch_nmi_watchdog();
4158 } while_each_thread(g
, p
);
4160 read_unlock(&tasklist_lock
);
4163 void __devinit
init_idle(task_t
*idle
, int cpu
)
4165 runqueue_t
*rq
= cpu_rq(cpu
);
4166 unsigned long flags
;
4168 idle
->sleep_avg
= 0;
4170 idle
->prio
= MAX_PRIO
;
4171 idle
->state
= TASK_RUNNING
;
4172 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4173 set_task_cpu(idle
, cpu
);
4175 spin_lock_irqsave(&rq
->lock
, flags
);
4176 rq
->curr
= rq
->idle
= idle
;
4177 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4180 set_tsk_need_resched(idle
);
4181 spin_unlock_irqrestore(&rq
->lock
, flags
);
4183 /* Set the preempt count _outside_ the spinlocks! */
4184 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4185 idle
->thread_info
->preempt_count
= (idle
->lock_depth
>= 0);
4187 idle
->thread_info
->preempt_count
= 0;
4192 * In a system that switches off the HZ timer nohz_cpu_mask
4193 * indicates which cpus entered this state. This is used
4194 * in the rcu update to wait only for active cpus. For system
4195 * which do not switch off the HZ timer nohz_cpu_mask should
4196 * always be CPU_MASK_NONE.
4198 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4202 * This is how migration works:
4204 * 1) we queue a migration_req_t structure in the source CPU's
4205 * runqueue and wake up that CPU's migration thread.
4206 * 2) we down() the locked semaphore => thread blocks.
4207 * 3) migration thread wakes up (implicitly it forces the migrated
4208 * thread off the CPU)
4209 * 4) it gets the migration request and checks whether the migrated
4210 * task is still in the wrong runqueue.
4211 * 5) if it's in the wrong runqueue then the migration thread removes
4212 * it and puts it into the right queue.
4213 * 6) migration thread up()s the semaphore.
4214 * 7) we wake up and the migration is done.
4218 * Change a given task's CPU affinity. Migrate the thread to a
4219 * proper CPU and schedule it away if the CPU it's executing on
4220 * is removed from the allowed bitmask.
4222 * NOTE: the caller must have a valid reference to the task, the
4223 * task must not exit() & deallocate itself prematurely. The
4224 * call is not atomic; no spinlocks may be held.
4226 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4228 unsigned long flags
;
4230 migration_req_t req
;
4233 rq
= task_rq_lock(p
, &flags
);
4234 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4239 p
->cpus_allowed
= new_mask
;
4240 /* Can the task run on the task's current CPU? If so, we're done */
4241 if (cpu_isset(task_cpu(p
), new_mask
))
4244 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4245 /* Need help from migration thread: drop lock and wait. */
4246 task_rq_unlock(rq
, &flags
);
4247 wake_up_process(rq
->migration_thread
);
4248 wait_for_completion(&req
.done
);
4249 tlb_migrate_finish(p
->mm
);
4253 task_rq_unlock(rq
, &flags
);
4257 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4260 * Move (not current) task off this cpu, onto dest cpu. We're doing
4261 * this because either it can't run here any more (set_cpus_allowed()
4262 * away from this CPU, or CPU going down), or because we're
4263 * attempting to rebalance this task on exec (sched_exec).
4265 * So we race with normal scheduler movements, but that's OK, as long
4266 * as the task is no longer on this CPU.
4268 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4270 runqueue_t
*rq_dest
, *rq_src
;
4272 if (unlikely(cpu_is_offline(dest_cpu
)))
4275 rq_src
= cpu_rq(src_cpu
);
4276 rq_dest
= cpu_rq(dest_cpu
);
4278 double_rq_lock(rq_src
, rq_dest
);
4279 /* Already moved. */
4280 if (task_cpu(p
) != src_cpu
)
4282 /* Affinity changed (again). */
4283 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4286 set_task_cpu(p
, dest_cpu
);
4289 * Sync timestamp with rq_dest's before activating.
4290 * The same thing could be achieved by doing this step
4291 * afterwards, and pretending it was a local activate.
4292 * This way is cleaner and logically correct.
4294 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4295 + rq_dest
->timestamp_last_tick
;
4296 deactivate_task(p
, rq_src
);
4297 activate_task(p
, rq_dest
, 0);
4298 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4299 resched_task(rq_dest
->curr
);
4303 double_rq_unlock(rq_src
, rq_dest
);
4307 * migration_thread - this is a highprio system thread that performs
4308 * thread migration by bumping thread off CPU then 'pushing' onto
4311 static int migration_thread(void * data
)
4314 int cpu
= (long)data
;
4317 BUG_ON(rq
->migration_thread
!= current
);
4319 set_current_state(TASK_INTERRUPTIBLE
);
4320 while (!kthread_should_stop()) {
4321 struct list_head
*head
;
4322 migration_req_t
*req
;
4324 if (current
->flags
& PF_FREEZE
)
4325 refrigerator(PF_FREEZE
);
4327 spin_lock_irq(&rq
->lock
);
4329 if (cpu_is_offline(cpu
)) {
4330 spin_unlock_irq(&rq
->lock
);
4334 if (rq
->active_balance
) {
4335 active_load_balance(rq
, cpu
);
4336 rq
->active_balance
= 0;
4339 head
= &rq
->migration_queue
;
4341 if (list_empty(head
)) {
4342 spin_unlock_irq(&rq
->lock
);
4344 set_current_state(TASK_INTERRUPTIBLE
);
4347 req
= list_entry(head
->next
, migration_req_t
, list
);
4348 list_del_init(head
->next
);
4350 if (req
->type
== REQ_MOVE_TASK
) {
4351 spin_unlock(&rq
->lock
);
4352 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4354 } else if (req
->type
== REQ_SET_DOMAIN
) {
4356 spin_unlock_irq(&rq
->lock
);
4358 spin_unlock_irq(&rq
->lock
);
4362 complete(&req
->done
);
4364 __set_current_state(TASK_RUNNING
);
4368 /* Wait for kthread_stop */
4369 set_current_state(TASK_INTERRUPTIBLE
);
4370 while (!kthread_should_stop()) {
4372 set_current_state(TASK_INTERRUPTIBLE
);
4374 __set_current_state(TASK_RUNNING
);
4378 #ifdef CONFIG_HOTPLUG_CPU
4379 /* Figure out where task on dead CPU should go, use force if neccessary. */
4380 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4386 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4387 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4388 dest_cpu
= any_online_cpu(mask
);
4390 /* On any allowed CPU? */
4391 if (dest_cpu
== NR_CPUS
)
4392 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4394 /* No more Mr. Nice Guy. */
4395 if (dest_cpu
== NR_CPUS
) {
4396 cpus_setall(tsk
->cpus_allowed
);
4397 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4400 * Don't tell them about moving exiting tasks or
4401 * kernel threads (both mm NULL), since they never
4404 if (tsk
->mm
&& printk_ratelimit())
4405 printk(KERN_INFO
"process %d (%s) no "
4406 "longer affine to cpu%d\n",
4407 tsk
->pid
, tsk
->comm
, dead_cpu
);
4409 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4413 * While a dead CPU has no uninterruptible tasks queued at this point,
4414 * it might still have a nonzero ->nr_uninterruptible counter, because
4415 * for performance reasons the counter is not stricly tracking tasks to
4416 * their home CPUs. So we just add the counter to another CPU's counter,
4417 * to keep the global sum constant after CPU-down:
4419 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4421 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4422 unsigned long flags
;
4424 local_irq_save(flags
);
4425 double_rq_lock(rq_src
, rq_dest
);
4426 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4427 rq_src
->nr_uninterruptible
= 0;
4428 double_rq_unlock(rq_src
, rq_dest
);
4429 local_irq_restore(flags
);
4432 /* Run through task list and migrate tasks from the dead cpu. */
4433 static void migrate_live_tasks(int src_cpu
)
4435 struct task_struct
*tsk
, *t
;
4437 write_lock_irq(&tasklist_lock
);
4439 do_each_thread(t
, tsk
) {
4443 if (task_cpu(tsk
) == src_cpu
)
4444 move_task_off_dead_cpu(src_cpu
, tsk
);
4445 } while_each_thread(t
, tsk
);
4447 write_unlock_irq(&tasklist_lock
);
4450 /* Schedules idle task to be the next runnable task on current CPU.
4451 * It does so by boosting its priority to highest possible and adding it to
4452 * the _front_ of runqueue. Used by CPU offline code.
4454 void sched_idle_next(void)
4456 int cpu
= smp_processor_id();
4457 runqueue_t
*rq
= this_rq();
4458 struct task_struct
*p
= rq
->idle
;
4459 unsigned long flags
;
4461 /* cpu has to be offline */
4462 BUG_ON(cpu_online(cpu
));
4464 /* Strictly not necessary since rest of the CPUs are stopped by now
4465 * and interrupts disabled on current cpu.
4467 spin_lock_irqsave(&rq
->lock
, flags
);
4469 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4470 /* Add idle task to _front_ of it's priority queue */
4471 __activate_idle_task(p
, rq
);
4473 spin_unlock_irqrestore(&rq
->lock
, flags
);
4476 /* Ensures that the idle task is using init_mm right before its cpu goes
4479 void idle_task_exit(void)
4481 struct mm_struct
*mm
= current
->active_mm
;
4483 BUG_ON(cpu_online(smp_processor_id()));
4486 switch_mm(mm
, &init_mm
, current
);
4490 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4492 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4494 /* Must be exiting, otherwise would be on tasklist. */
4495 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4497 /* Cannot have done final schedule yet: would have vanished. */
4498 BUG_ON(tsk
->flags
& PF_DEAD
);
4500 get_task_struct(tsk
);
4503 * Drop lock around migration; if someone else moves it,
4504 * that's OK. No task can be added to this CPU, so iteration is
4507 spin_unlock_irq(&rq
->lock
);
4508 move_task_off_dead_cpu(dead_cpu
, tsk
);
4509 spin_lock_irq(&rq
->lock
);
4511 put_task_struct(tsk
);
4514 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4515 static void migrate_dead_tasks(unsigned int dead_cpu
)
4518 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4520 for (arr
= 0; arr
< 2; arr
++) {
4521 for (i
= 0; i
< MAX_PRIO
; i
++) {
4522 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4523 while (!list_empty(list
))
4524 migrate_dead(dead_cpu
,
4525 list_entry(list
->next
, task_t
,
4530 #endif /* CONFIG_HOTPLUG_CPU */
4533 * migration_call - callback that gets triggered when a CPU is added.
4534 * Here we can start up the necessary migration thread for the new CPU.
4536 static int migration_call(struct notifier_block
*nfb
, unsigned long action
,
4539 int cpu
= (long)hcpu
;
4540 struct task_struct
*p
;
4541 struct runqueue
*rq
;
4542 unsigned long flags
;
4545 case CPU_UP_PREPARE
:
4546 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4549 p
->flags
|= PF_NOFREEZE
;
4550 kthread_bind(p
, cpu
);
4551 /* Must be high prio: stop_machine expects to yield to it. */
4552 rq
= task_rq_lock(p
, &flags
);
4553 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4554 task_rq_unlock(rq
, &flags
);
4555 cpu_rq(cpu
)->migration_thread
= p
;
4558 /* Strictly unneccessary, as first user will wake it. */
4559 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4561 #ifdef CONFIG_HOTPLUG_CPU
4562 case CPU_UP_CANCELED
:
4563 /* Unbind it from offline cpu so it can run. Fall thru. */
4564 kthread_bind(cpu_rq(cpu
)->migration_thread
,smp_processor_id());
4565 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4566 cpu_rq(cpu
)->migration_thread
= NULL
;
4569 migrate_live_tasks(cpu
);
4571 kthread_stop(rq
->migration_thread
);
4572 rq
->migration_thread
= NULL
;
4573 /* Idle task back to normal (off runqueue, low prio) */
4574 rq
= task_rq_lock(rq
->idle
, &flags
);
4575 deactivate_task(rq
->idle
, rq
);
4576 rq
->idle
->static_prio
= MAX_PRIO
;
4577 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4578 migrate_dead_tasks(cpu
);
4579 task_rq_unlock(rq
, &flags
);
4580 migrate_nr_uninterruptible(rq
);
4581 BUG_ON(rq
->nr_running
!= 0);
4583 /* No need to migrate the tasks: it was best-effort if
4584 * they didn't do lock_cpu_hotplug(). Just wake up
4585 * the requestors. */
4586 spin_lock_irq(&rq
->lock
);
4587 while (!list_empty(&rq
->migration_queue
)) {
4588 migration_req_t
*req
;
4589 req
= list_entry(rq
->migration_queue
.next
,
4590 migration_req_t
, list
);
4591 BUG_ON(req
->type
!= REQ_MOVE_TASK
);
4592 list_del_init(&req
->list
);
4593 complete(&req
->done
);
4595 spin_unlock_irq(&rq
->lock
);
4602 /* Register at highest priority so that task migration (migrate_all_tasks)
4603 * happens before everything else.
4605 static struct notifier_block __devinitdata migration_notifier
= {
4606 .notifier_call
= migration_call
,
4610 int __init
migration_init(void)
4612 void *cpu
= (void *)(long)smp_processor_id();
4613 /* Start one for boot CPU. */
4614 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4615 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4616 register_cpu_notifier(&migration_notifier
);
4622 #define SCHED_DOMAIN_DEBUG
4623 #ifdef SCHED_DOMAIN_DEBUG
4624 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4629 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4633 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4638 struct sched_group
*group
= sd
->groups
;
4639 cpumask_t groupmask
;
4641 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4642 cpus_clear(groupmask
);
4645 for (i
= 0; i
< level
+ 1; i
++)
4647 printk("domain %d: ", level
);
4649 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4650 printk("does not load-balance\n");
4652 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4656 printk("span %s\n", str
);
4658 if (!cpu_isset(cpu
, sd
->span
))
4659 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4660 if (!cpu_isset(cpu
, group
->cpumask
))
4661 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4664 for (i
= 0; i
< level
+ 2; i
++)
4670 printk(KERN_ERR
"ERROR: group is NULL\n");
4674 if (!group
->cpu_power
) {
4676 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4679 if (!cpus_weight(group
->cpumask
)) {
4681 printk(KERN_ERR
"ERROR: empty group\n");
4684 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4686 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4689 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4691 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4694 group
= group
->next
;
4695 } while (group
!= sd
->groups
);
4698 if (!cpus_equal(sd
->span
, groupmask
))
4699 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4705 if (!cpus_subset(groupmask
, sd
->span
))
4706 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4712 #define sched_domain_debug(sd, cpu) {}
4716 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4717 * hold the hotplug lock.
4719 void __devinit
cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
4721 migration_req_t req
;
4722 unsigned long flags
;
4723 runqueue_t
*rq
= cpu_rq(cpu
);
4726 sched_domain_debug(sd
, cpu
);
4728 spin_lock_irqsave(&rq
->lock
, flags
);
4730 if (cpu
== smp_processor_id() || !cpu_online(cpu
)) {
4733 init_completion(&req
.done
);
4734 req
.type
= REQ_SET_DOMAIN
;
4736 list_add(&req
.list
, &rq
->migration_queue
);
4740 spin_unlock_irqrestore(&rq
->lock
, flags
);
4743 wake_up_process(rq
->migration_thread
);
4744 wait_for_completion(&req
.done
);
4748 /* cpus with isolated domains */
4749 cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
4751 /* Setup the mask of cpus configured for isolated domains */
4752 static int __init
isolated_cpu_setup(char *str
)
4754 int ints
[NR_CPUS
], i
;
4756 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
4757 cpus_clear(cpu_isolated_map
);
4758 for (i
= 1; i
<= ints
[0]; i
++)
4759 if (ints
[i
] < NR_CPUS
)
4760 cpu_set(ints
[i
], cpu_isolated_map
);
4764 __setup ("isolcpus=", isolated_cpu_setup
);
4767 * init_sched_build_groups takes an array of groups, the cpumask we wish
4768 * to span, and a pointer to a function which identifies what group a CPU
4769 * belongs to. The return value of group_fn must be a valid index into the
4770 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
4771 * keep track of groups covered with a cpumask_t).
4773 * init_sched_build_groups will build a circular linked list of the groups
4774 * covered by the given span, and will set each group's ->cpumask correctly,
4775 * and ->cpu_power to 0.
4777 void __devinit
init_sched_build_groups(struct sched_group groups
[],
4778 cpumask_t span
, int (*group_fn
)(int cpu
))
4780 struct sched_group
*first
= NULL
, *last
= NULL
;
4781 cpumask_t covered
= CPU_MASK_NONE
;
4784 for_each_cpu_mask(i
, span
) {
4785 int group
= group_fn(i
);
4786 struct sched_group
*sg
= &groups
[group
];
4789 if (cpu_isset(i
, covered
))
4792 sg
->cpumask
= CPU_MASK_NONE
;
4795 for_each_cpu_mask(j
, span
) {
4796 if (group_fn(j
) != group
)
4799 cpu_set(j
, covered
);
4800 cpu_set(j
, sg
->cpumask
);
4812 #ifdef ARCH_HAS_SCHED_DOMAIN
4813 extern void __devinit
arch_init_sched_domains(void);
4814 extern void __devinit
arch_destroy_sched_domains(void);
4816 #ifdef CONFIG_SCHED_SMT
4817 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
4818 static struct sched_group sched_group_cpus
[NR_CPUS
];
4819 static int __devinit
cpu_to_cpu_group(int cpu
)
4825 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
4826 static struct sched_group sched_group_phys
[NR_CPUS
];
4827 static int __devinit
cpu_to_phys_group(int cpu
)
4829 #ifdef CONFIG_SCHED_SMT
4830 return first_cpu(cpu_sibling_map
[cpu
]);
4838 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
4839 static struct sched_group sched_group_nodes
[MAX_NUMNODES
];
4840 static int __devinit
cpu_to_node_group(int cpu
)
4842 return cpu_to_node(cpu
);
4846 #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
4848 * The domains setup code relies on siblings not spanning
4849 * multiple nodes. Make sure the architecture has a proper
4852 static void check_sibling_maps(void)
4856 for_each_online_cpu(i
) {
4857 for_each_cpu_mask(j
, cpu_sibling_map
[i
]) {
4858 if (cpu_to_node(i
) != cpu_to_node(j
)) {
4859 printk(KERN_INFO
"warning: CPU %d siblings map "
4860 "to different node - isolating "
4862 cpu_sibling_map
[i
] = cpumask_of_cpu(i
);
4871 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
4873 static void __devinit
arch_init_sched_domains(void)
4876 cpumask_t cpu_default_map
;
4878 #if defined(CONFIG_SCHED_SMT) && defined(CONFIG_NUMA)
4879 check_sibling_maps();
4882 * Setup mask for cpus without special case scheduling requirements.
4883 * For now this just excludes isolated cpus, but could be used to
4884 * exclude other special cases in the future.
4886 cpus_complement(cpu_default_map
, cpu_isolated_map
);
4887 cpus_and(cpu_default_map
, cpu_default_map
, cpu_online_map
);
4890 * Set up domains. Isolated domains just stay on the NULL domain.
4892 for_each_cpu_mask(i
, cpu_default_map
) {
4894 struct sched_domain
*sd
= NULL
, *p
;
4895 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
4897 cpus_and(nodemask
, nodemask
, cpu_default_map
);
4900 sd
= &per_cpu(node_domains
, i
);
4901 group
= cpu_to_node_group(i
);
4903 sd
->span
= cpu_default_map
;
4904 sd
->groups
= &sched_group_nodes
[group
];
4908 sd
= &per_cpu(phys_domains
, i
);
4909 group
= cpu_to_phys_group(i
);
4911 sd
->span
= nodemask
;
4913 sd
->groups
= &sched_group_phys
[group
];
4915 #ifdef CONFIG_SCHED_SMT
4917 sd
= &per_cpu(cpu_domains
, i
);
4918 group
= cpu_to_cpu_group(i
);
4919 *sd
= SD_SIBLING_INIT
;
4920 sd
->span
= cpu_sibling_map
[i
];
4921 cpus_and(sd
->span
, sd
->span
, cpu_default_map
);
4923 sd
->groups
= &sched_group_cpus
[group
];
4927 #ifdef CONFIG_SCHED_SMT
4928 /* Set up CPU (sibling) groups */
4929 for_each_online_cpu(i
) {
4930 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
4931 cpus_and(this_sibling_map
, this_sibling_map
, cpu_default_map
);
4932 if (i
!= first_cpu(this_sibling_map
))
4935 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
4940 /* Set up physical groups */
4941 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
4942 cpumask_t nodemask
= node_to_cpumask(i
);
4944 cpus_and(nodemask
, nodemask
, cpu_default_map
);
4945 if (cpus_empty(nodemask
))
4948 init_sched_build_groups(sched_group_phys
, nodemask
,
4949 &cpu_to_phys_group
);
4953 /* Set up node groups */
4954 init_sched_build_groups(sched_group_nodes
, cpu_default_map
,
4955 &cpu_to_node_group
);
4958 /* Calculate CPU power for physical packages and nodes */
4959 for_each_cpu_mask(i
, cpu_default_map
) {
4961 struct sched_domain
*sd
;
4962 #ifdef CONFIG_SCHED_SMT
4963 sd
= &per_cpu(cpu_domains
, i
);
4964 power
= SCHED_LOAD_SCALE
;
4965 sd
->groups
->cpu_power
= power
;
4968 sd
= &per_cpu(phys_domains
, i
);
4969 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
4970 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
4971 sd
->groups
->cpu_power
= power
;
4974 if (i
== first_cpu(sd
->groups
->cpumask
)) {
4975 /* Only add "power" once for each physical package. */
4976 sd
= &per_cpu(node_domains
, i
);
4977 sd
->groups
->cpu_power
+= power
;
4982 /* Attach the domains */
4983 for_each_online_cpu(i
) {
4984 struct sched_domain
*sd
;
4985 #ifdef CONFIG_SCHED_SMT
4986 sd
= &per_cpu(cpu_domains
, i
);
4988 sd
= &per_cpu(phys_domains
, i
);
4990 cpu_attach_domain(sd
, i
);
4994 #ifdef CONFIG_HOTPLUG_CPU
4995 static void __devinit
arch_destroy_sched_domains(void)
4997 /* Do nothing: everything is statically allocated. */
5001 #endif /* ARCH_HAS_SCHED_DOMAIN */
5003 #ifdef CONFIG_HOTPLUG_CPU
5005 * Force a reinitialization of the sched domains hierarchy. The domains
5006 * and groups cannot be updated in place without racing with the balancing
5007 * code, so we temporarily attach all running cpus to the NULL domain
5008 * which will prevent rebalancing while the sched domains are recalculated.
5010 static int update_sched_domains(struct notifier_block
*nfb
,
5011 unsigned long action
, void *hcpu
)
5016 case CPU_UP_PREPARE
:
5017 case CPU_DOWN_PREPARE
:
5018 for_each_online_cpu(i
)
5019 cpu_attach_domain(NULL
, i
);
5020 arch_destroy_sched_domains();
5023 case CPU_UP_CANCELED
:
5024 case CPU_DOWN_FAILED
:
5028 * Fall through and re-initialise the domains.
5035 /* The hotplug lock is already held by cpu_up/cpu_down */
5036 arch_init_sched_domains();
5042 void __init
sched_init_smp(void)
5045 arch_init_sched_domains();
5046 unlock_cpu_hotplug();
5047 /* XXX: Theoretical race here - CPU may be hotplugged now */
5048 hotcpu_notifier(update_sched_domains
, 0);
5051 void __init
sched_init_smp(void)
5054 #endif /* CONFIG_SMP */
5056 int in_sched_functions(unsigned long addr
)
5058 /* Linker adds these: start and end of __sched functions */
5059 extern char __sched_text_start
[], __sched_text_end
[];
5060 return in_lock_functions(addr
) ||
5061 (addr
>= (unsigned long)__sched_text_start
5062 && addr
< (unsigned long)__sched_text_end
);
5065 void __init
sched_init(void)
5070 for (i
= 0; i
< NR_CPUS
; i
++) {
5071 prio_array_t
*array
;
5074 spin_lock_init(&rq
->lock
);
5076 rq
->active
= rq
->arrays
;
5077 rq
->expired
= rq
->arrays
+ 1;
5078 rq
->best_expired_prio
= MAX_PRIO
;
5082 for (j
= 1; j
< 3; j
++)
5083 rq
->cpu_load
[j
] = 0;
5084 rq
->active_balance
= 0;
5086 rq
->migration_thread
= NULL
;
5087 INIT_LIST_HEAD(&rq
->migration_queue
);
5089 atomic_set(&rq
->nr_iowait
, 0);
5091 for (j
= 0; j
< 2; j
++) {
5092 array
= rq
->arrays
+ j
;
5093 for (k
= 0; k
< MAX_PRIO
; k
++) {
5094 INIT_LIST_HEAD(array
->queue
+ k
);
5095 __clear_bit(k
, array
->bitmap
);
5097 // delimiter for bitsearch
5098 __set_bit(MAX_PRIO
, array
->bitmap
);
5103 * The boot idle thread does lazy MMU switching as well:
5105 atomic_inc(&init_mm
.mm_count
);
5106 enter_lazy_tlb(&init_mm
, current
);
5109 * Make us the idle thread. Technically, schedule() should not be
5110 * called from this thread, however somewhere below it might be,
5111 * but because we are the idle thread, we just pick up running again
5112 * when this runqueue becomes "idle".
5114 init_idle(current
, smp_processor_id());
5117 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5118 void __might_sleep(char *file
, int line
)
5120 #if defined(in_atomic)
5121 static unsigned long prev_jiffy
; /* ratelimiting */
5123 if ((in_atomic() || irqs_disabled()) &&
5124 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
5125 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
5127 prev_jiffy
= jiffies
;
5128 printk(KERN_ERR
"Debug: sleeping function called from invalid"
5129 " context at %s:%d\n", file
, line
);
5130 printk("in_atomic():%d, irqs_disabled():%d\n",
5131 in_atomic(), irqs_disabled());
5136 EXPORT_SYMBOL(__might_sleep
);
5139 #ifdef CONFIG_MAGIC_SYSRQ
5140 void normalize_rt_tasks(void)
5142 struct task_struct
*p
;
5143 prio_array_t
*array
;
5144 unsigned long flags
;
5147 read_lock_irq(&tasklist_lock
);
5148 for_each_process (p
) {
5152 rq
= task_rq_lock(p
, &flags
);
5156 deactivate_task(p
, task_rq(p
));
5157 __setscheduler(p
, SCHED_NORMAL
, 0);
5159 __activate_task(p
, task_rq(p
));
5160 resched_task(rq
->curr
);
5163 task_rq_unlock(rq
, &flags
);
5165 read_unlock_irq(&tasklist_lock
);
5168 #endif /* CONFIG_MAGIC_SYSRQ */