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
);
264 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
265 * See detach_destroy_domains: synchronize_sched for details.
267 * The domain tree of any CPU may only be accessed from within
268 * preempt-disabled sections.
270 #define for_each_domain(cpu, domain) \
271 for (domain = rcu_dereference(cpu_rq(cpu)->sd); domain; domain = domain->parent)
273 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
274 #define this_rq() (&__get_cpu_var(runqueues))
275 #define task_rq(p) cpu_rq(task_cpu(p))
276 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
278 #ifndef prepare_arch_switch
279 # define prepare_arch_switch(next) do { } while (0)
281 #ifndef finish_arch_switch
282 # define finish_arch_switch(prev) do { } while (0)
285 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
286 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
288 return rq
->curr
== p
;
291 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
295 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
297 #ifdef CONFIG_DEBUG_SPINLOCK
298 /* this is a valid case when another task releases the spinlock */
299 rq
->lock
.owner
= current
;
301 spin_unlock_irq(&rq
->lock
);
304 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
305 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
310 return rq
->curr
== p
;
314 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
318 * We can optimise this out completely for !SMP, because the
319 * SMP rebalancing from interrupt is the only thing that cares
324 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
325 spin_unlock_irq(&rq
->lock
);
327 spin_unlock(&rq
->lock
);
331 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
335 * After ->oncpu is cleared, the task can be moved to a different CPU.
336 * We must ensure this doesn't happen until the switch is completely
342 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
346 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
349 * task_rq_lock - lock the runqueue a given task resides on and disable
350 * interrupts. Note the ordering: we can safely lookup the task_rq without
351 * explicitly disabling preemption.
353 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
359 local_irq_save(*flags
);
361 spin_lock(&rq
->lock
);
362 if (unlikely(rq
!= task_rq(p
))) {
363 spin_unlock_irqrestore(&rq
->lock
, *flags
);
364 goto repeat_lock_task
;
369 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
372 spin_unlock_irqrestore(&rq
->lock
, *flags
);
375 #ifdef CONFIG_SCHEDSTATS
377 * bump this up when changing the output format or the meaning of an existing
378 * format, so that tools can adapt (or abort)
380 #define SCHEDSTAT_VERSION 12
382 static int show_schedstat(struct seq_file
*seq
, void *v
)
386 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
387 seq_printf(seq
, "timestamp %lu\n", jiffies
);
388 for_each_online_cpu(cpu
) {
389 runqueue_t
*rq
= cpu_rq(cpu
);
391 struct sched_domain
*sd
;
395 /* runqueue-specific stats */
397 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
398 cpu
, rq
->yld_both_empty
,
399 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
400 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
401 rq
->ttwu_cnt
, rq
->ttwu_local
,
402 rq
->rq_sched_info
.cpu_time
,
403 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
405 seq_printf(seq
, "\n");
408 /* domain-specific stats */
410 for_each_domain(cpu
, sd
) {
411 enum idle_type itype
;
412 char mask_str
[NR_CPUS
];
414 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
415 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
416 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
418 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
420 sd
->lb_balanced
[itype
],
421 sd
->lb_failed
[itype
],
422 sd
->lb_imbalance
[itype
],
423 sd
->lb_gained
[itype
],
424 sd
->lb_hot_gained
[itype
],
425 sd
->lb_nobusyq
[itype
],
426 sd
->lb_nobusyg
[itype
]);
428 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
429 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
430 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
431 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
432 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
440 static int schedstat_open(struct inode
*inode
, struct file
*file
)
442 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
443 char *buf
= kmalloc(size
, GFP_KERNEL
);
449 res
= single_open(file
, show_schedstat
, NULL
);
451 m
= file
->private_data
;
459 struct file_operations proc_schedstat_operations
= {
460 .open
= schedstat_open
,
463 .release
= single_release
,
466 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
467 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
468 #else /* !CONFIG_SCHEDSTATS */
469 # define schedstat_inc(rq, field) do { } while (0)
470 # define schedstat_add(rq, field, amt) do { } while (0)
474 * rq_lock - lock a given runqueue and disable interrupts.
476 static inline runqueue_t
*this_rq_lock(void)
483 spin_lock(&rq
->lock
);
488 #ifdef CONFIG_SCHEDSTATS
490 * Called when a process is dequeued from the active array and given
491 * the cpu. We should note that with the exception of interactive
492 * tasks, the expired queue will become the active queue after the active
493 * queue is empty, without explicitly dequeuing and requeuing tasks in the
494 * expired queue. (Interactive tasks may be requeued directly to the
495 * active queue, thus delaying tasks in the expired queue from running;
496 * see scheduler_tick()).
498 * This function is only called from sched_info_arrive(), rather than
499 * dequeue_task(). Even though a task may be queued and dequeued multiple
500 * times as it is shuffled about, we're really interested in knowing how
501 * long it was from the *first* time it was queued to the time that it
504 static inline void sched_info_dequeued(task_t
*t
)
506 t
->sched_info
.last_queued
= 0;
510 * Called when a task finally hits the cpu. We can now calculate how
511 * long it was waiting to run. We also note when it began so that we
512 * can keep stats on how long its timeslice is.
514 static inline void sched_info_arrive(task_t
*t
)
516 unsigned long now
= jiffies
, diff
= 0;
517 struct runqueue
*rq
= task_rq(t
);
519 if (t
->sched_info
.last_queued
)
520 diff
= now
- t
->sched_info
.last_queued
;
521 sched_info_dequeued(t
);
522 t
->sched_info
.run_delay
+= diff
;
523 t
->sched_info
.last_arrival
= now
;
524 t
->sched_info
.pcnt
++;
529 rq
->rq_sched_info
.run_delay
+= diff
;
530 rq
->rq_sched_info
.pcnt
++;
534 * Called when a process is queued into either the active or expired
535 * array. The time is noted and later used to determine how long we
536 * had to wait for us to reach the cpu. Since the expired queue will
537 * become the active queue after active queue is empty, without dequeuing
538 * and requeuing any tasks, we are interested in queuing to either. It
539 * is unusual but not impossible for tasks to be dequeued and immediately
540 * requeued in the same or another array: this can happen in sched_yield(),
541 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
544 * This function is only called from enqueue_task(), but also only updates
545 * the timestamp if it is already not set. It's assumed that
546 * sched_info_dequeued() will clear that stamp when appropriate.
548 static inline void sched_info_queued(task_t
*t
)
550 if (!t
->sched_info
.last_queued
)
551 t
->sched_info
.last_queued
= jiffies
;
555 * Called when a process ceases being the active-running process, either
556 * voluntarily or involuntarily. Now we can calculate how long we ran.
558 static inline void sched_info_depart(task_t
*t
)
560 struct runqueue
*rq
= task_rq(t
);
561 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
563 t
->sched_info
.cpu_time
+= diff
;
566 rq
->rq_sched_info
.cpu_time
+= diff
;
570 * Called when tasks are switched involuntarily due, typically, to expiring
571 * their time slice. (This may also be called when switching to or from
572 * the idle task.) We are only called when prev != next.
574 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
576 struct runqueue
*rq
= task_rq(prev
);
579 * prev now departs the cpu. It's not interesting to record
580 * stats about how efficient we were at scheduling the idle
583 if (prev
!= rq
->idle
)
584 sched_info_depart(prev
);
586 if (next
!= rq
->idle
)
587 sched_info_arrive(next
);
590 #define sched_info_queued(t) do { } while (0)
591 #define sched_info_switch(t, next) do { } while (0)
592 #endif /* CONFIG_SCHEDSTATS */
595 * Adding/removing a task to/from a priority array:
597 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
600 list_del(&p
->run_list
);
601 if (list_empty(array
->queue
+ p
->prio
))
602 __clear_bit(p
->prio
, array
->bitmap
);
605 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
607 sched_info_queued(p
);
608 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
609 __set_bit(p
->prio
, array
->bitmap
);
615 * Put task to the end of the run list without the overhead of dequeue
616 * followed by enqueue.
618 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
620 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
623 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
625 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
626 __set_bit(p
->prio
, array
->bitmap
);
632 * effective_prio - return the priority that is based on the static
633 * priority but is modified by bonuses/penalties.
635 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
636 * into the -5 ... 0 ... +5 bonus/penalty range.
638 * We use 25% of the full 0...39 priority range so that:
640 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
641 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
643 * Both properties are important to certain workloads.
645 static int effective_prio(task_t
*p
)
652 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
654 prio
= p
->static_prio
- bonus
;
655 if (prio
< MAX_RT_PRIO
)
657 if (prio
> MAX_PRIO
-1)
663 * __activate_task - move a task to the runqueue.
665 static inline void __activate_task(task_t
*p
, runqueue_t
*rq
)
667 enqueue_task(p
, rq
->active
);
672 * __activate_idle_task - move idle task to the _front_ of runqueue.
674 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
676 enqueue_task_head(p
, rq
->active
);
680 static int recalc_task_prio(task_t
*p
, unsigned long long now
)
682 /* Caller must always ensure 'now >= p->timestamp' */
683 unsigned long long __sleep_time
= now
- p
->timestamp
;
684 unsigned long sleep_time
;
686 if (__sleep_time
> NS_MAX_SLEEP_AVG
)
687 sleep_time
= NS_MAX_SLEEP_AVG
;
689 sleep_time
= (unsigned long)__sleep_time
;
691 if (likely(sleep_time
> 0)) {
693 * User tasks that sleep a long time are categorised as
694 * idle and will get just interactive status to stay active &
695 * prevent them suddenly becoming cpu hogs and starving
698 if (p
->mm
&& p
->activated
!= -1 &&
699 sleep_time
> INTERACTIVE_SLEEP(p
)) {
700 p
->sleep_avg
= JIFFIES_TO_NS(MAX_SLEEP_AVG
-
704 * The lower the sleep avg a task has the more
705 * rapidly it will rise with sleep time.
707 sleep_time
*= (MAX_BONUS
- CURRENT_BONUS(p
)) ? : 1;
710 * Tasks waking from uninterruptible sleep are
711 * limited in their sleep_avg rise as they
712 * are likely to be waiting on I/O
714 if (p
->activated
== -1 && p
->mm
) {
715 if (p
->sleep_avg
>= INTERACTIVE_SLEEP(p
))
717 else if (p
->sleep_avg
+ sleep_time
>=
718 INTERACTIVE_SLEEP(p
)) {
719 p
->sleep_avg
= INTERACTIVE_SLEEP(p
);
725 * This code gives a bonus to interactive tasks.
727 * The boost works by updating the 'average sleep time'
728 * value here, based on ->timestamp. The more time a
729 * task spends sleeping, the higher the average gets -
730 * and the higher the priority boost gets as well.
732 p
->sleep_avg
+= sleep_time
;
734 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
735 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
739 return effective_prio(p
);
743 * activate_task - move a task to the runqueue and do priority recalculation
745 * Update all the scheduling statistics stuff. (sleep average
746 * calculation, priority modifiers, etc.)
748 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
750 unsigned long long now
;
755 /* Compensate for drifting sched_clock */
756 runqueue_t
*this_rq
= this_rq();
757 now
= (now
- this_rq
->timestamp_last_tick
)
758 + rq
->timestamp_last_tick
;
762 p
->prio
= recalc_task_prio(p
, now
);
765 * This checks to make sure it's not an uninterruptible task
766 * that is now waking up.
770 * Tasks which were woken up by interrupts (ie. hw events)
771 * are most likely of interactive nature. So we give them
772 * the credit of extending their sleep time to the period
773 * of time they spend on the runqueue, waiting for execution
774 * on a CPU, first time around:
780 * Normal first-time wakeups get a credit too for
781 * on-runqueue time, but it will be weighted down:
788 __activate_task(p
, rq
);
792 * deactivate_task - remove a task from the runqueue.
794 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
797 dequeue_task(p
, p
->array
);
802 * resched_task - mark a task 'to be rescheduled now'.
804 * On UP this means the setting of the need_resched flag, on SMP it
805 * might also involve a cross-CPU call to trigger the scheduler on
809 static void resched_task(task_t
*p
)
811 int need_resched
, nrpolling
;
813 assert_spin_locked(&task_rq(p
)->lock
);
815 /* minimise the chance of sending an interrupt to poll_idle() */
816 nrpolling
= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
817 need_resched
= test_and_set_tsk_thread_flag(p
,TIF_NEED_RESCHED
);
818 nrpolling
|= test_tsk_thread_flag(p
,TIF_POLLING_NRFLAG
);
820 if (!need_resched
&& !nrpolling
&& (task_cpu(p
) != smp_processor_id()))
821 smp_send_reschedule(task_cpu(p
));
824 static inline void resched_task(task_t
*p
)
826 set_tsk_need_resched(p
);
831 * task_curr - is this task currently executing on a CPU?
832 * @p: the task in question.
834 inline int task_curr(const task_t
*p
)
836 return cpu_curr(task_cpu(p
)) == p
;
841 struct list_head list
;
846 struct completion done
;
850 * The task's runqueue lock must be held.
851 * Returns true if you have to wait for migration thread.
853 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
855 runqueue_t
*rq
= task_rq(p
);
858 * If the task is not on a runqueue (and not running), then
859 * it is sufficient to simply update the task's cpu field.
861 if (!p
->array
&& !task_running(rq
, p
)) {
862 set_task_cpu(p
, dest_cpu
);
866 init_completion(&req
->done
);
868 req
->dest_cpu
= dest_cpu
;
869 list_add(&req
->list
, &rq
->migration_queue
);
874 * wait_task_inactive - wait for a thread to unschedule.
876 * The caller must ensure that the task *will* unschedule sometime soon,
877 * else this function might spin for a *long* time. This function can't
878 * be called with interrupts off, or it may introduce deadlock with
879 * smp_call_function() if an IPI is sent by the same process we are
880 * waiting to become inactive.
882 void wait_task_inactive(task_t
*p
)
889 rq
= task_rq_lock(p
, &flags
);
890 /* Must be off runqueue entirely, not preempted. */
891 if (unlikely(p
->array
|| task_running(rq
, p
))) {
892 /* If it's preempted, we yield. It could be a while. */
893 preempted
= !task_running(rq
, p
);
894 task_rq_unlock(rq
, &flags
);
900 task_rq_unlock(rq
, &flags
);
904 * kick_process - kick a running thread to enter/exit the kernel
905 * @p: the to-be-kicked thread
907 * Cause a process which is running on another CPU to enter
908 * kernel-mode, without any delay. (to get signals handled.)
910 * NOTE: this function doesnt have to take the runqueue lock,
911 * because all it wants to ensure is that the remote task enters
912 * the kernel. If the IPI races and the task has been migrated
913 * to another CPU then no harm is done and the purpose has been
916 void kick_process(task_t
*p
)
922 if ((cpu
!= smp_processor_id()) && task_curr(p
))
923 smp_send_reschedule(cpu
);
928 * Return a low guess at the load of a migration-source cpu.
930 * We want to under-estimate the load of migration sources, to
931 * balance conservatively.
933 static inline unsigned long source_load(int cpu
, int type
)
935 runqueue_t
*rq
= cpu_rq(cpu
);
936 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
940 return min(rq
->cpu_load
[type
-1], load_now
);
944 * Return a high guess at the load of a migration-target cpu
946 static inline unsigned long target_load(int cpu
, int type
)
948 runqueue_t
*rq
= cpu_rq(cpu
);
949 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
953 return max(rq
->cpu_load
[type
-1], load_now
);
957 * find_idlest_group finds and returns the least busy CPU group within the
960 static struct sched_group
*
961 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
963 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
964 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
965 int load_idx
= sd
->forkexec_idx
;
966 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
969 unsigned long load
, avg_load
;
973 /* Skip over this group if it has no CPUs allowed */
974 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
977 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
979 /* Tally up the load of all CPUs in the group */
982 for_each_cpu_mask(i
, group
->cpumask
) {
983 /* Bias balancing toward cpus of our domain */
985 load
= source_load(i
, load_idx
);
987 load
= target_load(i
, load_idx
);
992 /* Adjust by relative CPU power of the group */
993 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
996 this_load
= avg_load
;
998 } else if (avg_load
< min_load
) {
1003 group
= group
->next
;
1004 } while (group
!= sd
->groups
);
1006 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1012 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1015 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1018 unsigned long load
, min_load
= ULONG_MAX
;
1022 /* Traverse only the allowed CPUs */
1023 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1025 for_each_cpu_mask(i
, tmp
) {
1026 load
= source_load(i
, 0);
1028 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1038 * sched_balance_self: balance the current task (running on cpu) in domains
1039 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1042 * Balance, ie. select the least loaded group.
1044 * Returns the target CPU number, or the same CPU if no balancing is needed.
1046 * preempt must be disabled.
1048 static int sched_balance_self(int cpu
, int flag
)
1050 struct task_struct
*t
= current
;
1051 struct sched_domain
*tmp
, *sd
= NULL
;
1053 for_each_domain(cpu
, tmp
)
1054 if (tmp
->flags
& flag
)
1059 struct sched_group
*group
;
1064 group
= find_idlest_group(sd
, t
, cpu
);
1068 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1069 if (new_cpu
== -1 || new_cpu
== cpu
)
1072 /* Now try balancing at a lower domain level */
1076 weight
= cpus_weight(span
);
1077 for_each_domain(cpu
, tmp
) {
1078 if (weight
<= cpus_weight(tmp
->span
))
1080 if (tmp
->flags
& flag
)
1083 /* while loop will break here if sd == NULL */
1089 #endif /* CONFIG_SMP */
1092 * wake_idle() will wake a task on an idle cpu if task->cpu is
1093 * not idle and an idle cpu is available. The span of cpus to
1094 * search starts with cpus closest then further out as needed,
1095 * so we always favor a closer, idle cpu.
1097 * Returns the CPU we should wake onto.
1099 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1100 static int wake_idle(int cpu
, task_t
*p
)
1103 struct sched_domain
*sd
;
1109 for_each_domain(cpu
, sd
) {
1110 if (sd
->flags
& SD_WAKE_IDLE
) {
1111 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1112 for_each_cpu_mask(i
, tmp
) {
1123 static inline int wake_idle(int cpu
, task_t
*p
)
1130 * try_to_wake_up - wake up a thread
1131 * @p: the to-be-woken-up thread
1132 * @state: the mask of task states that can be woken
1133 * @sync: do a synchronous wakeup?
1135 * Put it on the run-queue if it's not already there. The "current"
1136 * thread is always on the run-queue (except when the actual
1137 * re-schedule is in progress), and as such you're allowed to do
1138 * the simpler "current->state = TASK_RUNNING" to mark yourself
1139 * runnable without the overhead of this.
1141 * returns failure only if the task is already active.
1143 static int try_to_wake_up(task_t
*p
, unsigned int state
, int sync
)
1145 int cpu
, this_cpu
, success
= 0;
1146 unsigned long flags
;
1150 unsigned long load
, this_load
;
1151 struct sched_domain
*sd
, *this_sd
= NULL
;
1155 rq
= task_rq_lock(p
, &flags
);
1156 old_state
= p
->state
;
1157 if (!(old_state
& state
))
1164 this_cpu
= smp_processor_id();
1167 if (unlikely(task_running(rq
, p
)))
1172 schedstat_inc(rq
, ttwu_cnt
);
1173 if (cpu
== this_cpu
) {
1174 schedstat_inc(rq
, ttwu_local
);
1178 for_each_domain(this_cpu
, sd
) {
1179 if (cpu_isset(cpu
, sd
->span
)) {
1180 schedstat_inc(sd
, ttwu_wake_remote
);
1186 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1190 * Check for affine wakeup and passive balancing possibilities.
1193 int idx
= this_sd
->wake_idx
;
1194 unsigned int imbalance
;
1196 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1198 load
= source_load(cpu
, idx
);
1199 this_load
= target_load(this_cpu
, idx
);
1201 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1203 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1204 unsigned long tl
= this_load
;
1206 * If sync wakeup then subtract the (maximum possible)
1207 * effect of the currently running task from the load
1208 * of the current CPU:
1211 tl
-= SCHED_LOAD_SCALE
;
1214 tl
+ target_load(cpu
, idx
) <= SCHED_LOAD_SCALE
) ||
1215 100*(tl
+ SCHED_LOAD_SCALE
) <= imbalance
*load
) {
1217 * This domain has SD_WAKE_AFFINE and
1218 * p is cache cold in this domain, and
1219 * there is no bad imbalance.
1221 schedstat_inc(this_sd
, ttwu_move_affine
);
1227 * Start passive balancing when half the imbalance_pct
1230 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1231 if (imbalance
*this_load
<= 100*load
) {
1232 schedstat_inc(this_sd
, ttwu_move_balance
);
1238 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1240 new_cpu
= wake_idle(new_cpu
, p
);
1241 if (new_cpu
!= cpu
) {
1242 set_task_cpu(p
, new_cpu
);
1243 task_rq_unlock(rq
, &flags
);
1244 /* might preempt at this point */
1245 rq
= task_rq_lock(p
, &flags
);
1246 old_state
= p
->state
;
1247 if (!(old_state
& state
))
1252 this_cpu
= smp_processor_id();
1257 #endif /* CONFIG_SMP */
1258 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1259 rq
->nr_uninterruptible
--;
1261 * Tasks on involuntary sleep don't earn
1262 * sleep_avg beyond just interactive state.
1268 * Tasks that have marked their sleep as noninteractive get
1269 * woken up without updating their sleep average. (i.e. their
1270 * sleep is handled in a priority-neutral manner, no priority
1271 * boost and no penalty.)
1273 if (old_state
& TASK_NONINTERACTIVE
)
1274 __activate_task(p
, rq
);
1276 activate_task(p
, rq
, cpu
== this_cpu
);
1278 * Sync wakeups (i.e. those types of wakeups where the waker
1279 * has indicated that it will leave the CPU in short order)
1280 * don't trigger a preemption, if the woken up task will run on
1281 * this cpu. (in this case the 'I will reschedule' promise of
1282 * the waker guarantees that the freshly woken up task is going
1283 * to be considered on this CPU.)
1285 if (!sync
|| cpu
!= this_cpu
) {
1286 if (TASK_PREEMPTS_CURR(p
, rq
))
1287 resched_task(rq
->curr
);
1292 p
->state
= TASK_RUNNING
;
1294 task_rq_unlock(rq
, &flags
);
1299 int fastcall
wake_up_process(task_t
*p
)
1301 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1302 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1305 EXPORT_SYMBOL(wake_up_process
);
1307 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1309 return try_to_wake_up(p
, state
, 0);
1313 * Perform scheduler related setup for a newly forked process p.
1314 * p is forked by current.
1316 void fastcall
sched_fork(task_t
*p
, int clone_flags
)
1318 int cpu
= get_cpu();
1321 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1323 set_task_cpu(p
, cpu
);
1326 * We mark the process as running here, but have not actually
1327 * inserted it onto the runqueue yet. This guarantees that
1328 * nobody will actually run it, and a signal or other external
1329 * event cannot wake it up and insert it on the runqueue either.
1331 p
->state
= TASK_RUNNING
;
1332 INIT_LIST_HEAD(&p
->run_list
);
1334 #ifdef CONFIG_SCHEDSTATS
1335 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1337 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1340 #ifdef CONFIG_PREEMPT
1341 /* Want to start with kernel preemption disabled. */
1342 p
->thread_info
->preempt_count
= 1;
1345 * Share the timeslice between parent and child, thus the
1346 * total amount of pending timeslices in the system doesn't change,
1347 * resulting in more scheduling fairness.
1349 local_irq_disable();
1350 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1352 * The remainder of the first timeslice might be recovered by
1353 * the parent if the child exits early enough.
1355 p
->first_time_slice
= 1;
1356 current
->time_slice
>>= 1;
1357 p
->timestamp
= sched_clock();
1358 if (unlikely(!current
->time_slice
)) {
1360 * This case is rare, it happens when the parent has only
1361 * a single jiffy left from its timeslice. Taking the
1362 * runqueue lock is not a problem.
1364 current
->time_slice
= 1;
1372 * wake_up_new_task - wake up a newly created task for the first time.
1374 * This function will do some initial scheduler statistics housekeeping
1375 * that must be done for every newly created context, then puts the task
1376 * on the runqueue and wakes it.
1378 void fastcall
wake_up_new_task(task_t
*p
, unsigned long clone_flags
)
1380 unsigned long flags
;
1382 runqueue_t
*rq
, *this_rq
;
1384 rq
= task_rq_lock(p
, &flags
);
1385 BUG_ON(p
->state
!= TASK_RUNNING
);
1386 this_cpu
= smp_processor_id();
1390 * We decrease the sleep average of forking parents
1391 * and children as well, to keep max-interactive tasks
1392 * from forking tasks that are max-interactive. The parent
1393 * (current) is done further down, under its lock.
1395 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1396 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1398 p
->prio
= effective_prio(p
);
1400 if (likely(cpu
== this_cpu
)) {
1401 if (!(clone_flags
& CLONE_VM
)) {
1403 * The VM isn't cloned, so we're in a good position to
1404 * do child-runs-first in anticipation of an exec. This
1405 * usually avoids a lot of COW overhead.
1407 if (unlikely(!current
->array
))
1408 __activate_task(p
, rq
);
1410 p
->prio
= current
->prio
;
1411 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1412 p
->array
= current
->array
;
1413 p
->array
->nr_active
++;
1418 /* Run child last */
1419 __activate_task(p
, rq
);
1421 * We skip the following code due to cpu == this_cpu
1423 * task_rq_unlock(rq, &flags);
1424 * this_rq = task_rq_lock(current, &flags);
1428 this_rq
= cpu_rq(this_cpu
);
1431 * Not the local CPU - must adjust timestamp. This should
1432 * get optimised away in the !CONFIG_SMP case.
1434 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1435 + rq
->timestamp_last_tick
;
1436 __activate_task(p
, rq
);
1437 if (TASK_PREEMPTS_CURR(p
, rq
))
1438 resched_task(rq
->curr
);
1441 * Parent and child are on different CPUs, now get the
1442 * parent runqueue to update the parent's ->sleep_avg:
1444 task_rq_unlock(rq
, &flags
);
1445 this_rq
= task_rq_lock(current
, &flags
);
1447 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1448 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1449 task_rq_unlock(this_rq
, &flags
);
1453 * Potentially available exiting-child timeslices are
1454 * retrieved here - this way the parent does not get
1455 * penalized for creating too many threads.
1457 * (this cannot be used to 'generate' timeslices
1458 * artificially, because any timeslice recovered here
1459 * was given away by the parent in the first place.)
1461 void fastcall
sched_exit(task_t
*p
)
1463 unsigned long flags
;
1467 * If the child was a (relative-) CPU hog then decrease
1468 * the sleep_avg of the parent as well.
1470 rq
= task_rq_lock(p
->parent
, &flags
);
1471 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1472 p
->parent
->time_slice
+= p
->time_slice
;
1473 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1474 p
->parent
->time_slice
= task_timeslice(p
);
1476 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1477 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1478 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1480 task_rq_unlock(rq
, &flags
);
1484 * prepare_task_switch - prepare to switch tasks
1485 * @rq: the runqueue preparing to switch
1486 * @next: the task we are going to switch to.
1488 * This is called with the rq lock held and interrupts off. It must
1489 * be paired with a subsequent finish_task_switch after the context
1492 * prepare_task_switch sets up locking and calls architecture specific
1495 static inline void prepare_task_switch(runqueue_t
*rq
, task_t
*next
)
1497 prepare_lock_switch(rq
, next
);
1498 prepare_arch_switch(next
);
1502 * finish_task_switch - clean up after a task-switch
1503 * @rq: runqueue associated with task-switch
1504 * @prev: the thread we just switched away from.
1506 * finish_task_switch must be called after the context switch, paired
1507 * with a prepare_task_switch call before the context switch.
1508 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1509 * and do any other architecture-specific cleanup actions.
1511 * Note that we may have delayed dropping an mm in context_switch(). If
1512 * so, we finish that here outside of the runqueue lock. (Doing it
1513 * with the lock held can cause deadlocks; see schedule() for
1516 static inline void finish_task_switch(runqueue_t
*rq
, task_t
*prev
)
1517 __releases(rq
->lock
)
1519 struct mm_struct
*mm
= rq
->prev_mm
;
1520 unsigned long prev_task_flags
;
1525 * A task struct has one reference for the use as "current".
1526 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1527 * calls schedule one last time. The schedule call will never return,
1528 * and the scheduled task must drop that reference.
1529 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1530 * still held, otherwise prev could be scheduled on another cpu, die
1531 * there before we look at prev->state, and then the reference would
1533 * Manfred Spraul <manfred@colorfullife.com>
1535 prev_task_flags
= prev
->flags
;
1536 finish_arch_switch(prev
);
1537 finish_lock_switch(rq
, prev
);
1540 if (unlikely(prev_task_flags
& PF_DEAD
))
1541 put_task_struct(prev
);
1545 * schedule_tail - first thing a freshly forked thread must call.
1546 * @prev: the thread we just switched away from.
1548 asmlinkage
void schedule_tail(task_t
*prev
)
1549 __releases(rq
->lock
)
1551 runqueue_t
*rq
= this_rq();
1552 finish_task_switch(rq
, prev
);
1553 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1554 /* In this case, finish_task_switch does not reenable preemption */
1557 if (current
->set_child_tid
)
1558 put_user(current
->pid
, current
->set_child_tid
);
1562 * context_switch - switch to the new MM and the new
1563 * thread's register state.
1566 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1568 struct mm_struct
*mm
= next
->mm
;
1569 struct mm_struct
*oldmm
= prev
->active_mm
;
1571 if (unlikely(!mm
)) {
1572 next
->active_mm
= oldmm
;
1573 atomic_inc(&oldmm
->mm_count
);
1574 enter_lazy_tlb(oldmm
, next
);
1576 switch_mm(oldmm
, mm
, next
);
1578 if (unlikely(!prev
->mm
)) {
1579 prev
->active_mm
= NULL
;
1580 WARN_ON(rq
->prev_mm
);
1581 rq
->prev_mm
= oldmm
;
1584 /* Here we just switch the register state and the stack. */
1585 switch_to(prev
, next
, prev
);
1591 * nr_running, nr_uninterruptible and nr_context_switches:
1593 * externally visible scheduler statistics: current number of runnable
1594 * threads, current number of uninterruptible-sleeping threads, total
1595 * number of context switches performed since bootup.
1597 unsigned long nr_running(void)
1599 unsigned long i
, sum
= 0;
1601 for_each_online_cpu(i
)
1602 sum
+= cpu_rq(i
)->nr_running
;
1607 unsigned long nr_uninterruptible(void)
1609 unsigned long i
, sum
= 0;
1612 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1615 * Since we read the counters lockless, it might be slightly
1616 * inaccurate. Do not allow it to go below zero though:
1618 if (unlikely((long)sum
< 0))
1624 unsigned long long nr_context_switches(void)
1626 unsigned long long i
, sum
= 0;
1629 sum
+= cpu_rq(i
)->nr_switches
;
1634 unsigned long nr_iowait(void)
1636 unsigned long i
, sum
= 0;
1639 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1647 * double_rq_lock - safely lock two runqueues
1649 * Note this does not disable interrupts like task_rq_lock,
1650 * you need to do so manually before calling.
1652 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1653 __acquires(rq1
->lock
)
1654 __acquires(rq2
->lock
)
1657 spin_lock(&rq1
->lock
);
1658 __acquire(rq2
->lock
); /* Fake it out ;) */
1661 spin_lock(&rq1
->lock
);
1662 spin_lock(&rq2
->lock
);
1664 spin_lock(&rq2
->lock
);
1665 spin_lock(&rq1
->lock
);
1671 * double_rq_unlock - safely unlock two runqueues
1673 * Note this does not restore interrupts like task_rq_unlock,
1674 * you need to do so manually after calling.
1676 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1677 __releases(rq1
->lock
)
1678 __releases(rq2
->lock
)
1680 spin_unlock(&rq1
->lock
);
1682 spin_unlock(&rq2
->lock
);
1684 __release(rq2
->lock
);
1688 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1690 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1691 __releases(this_rq
->lock
)
1692 __acquires(busiest
->lock
)
1693 __acquires(this_rq
->lock
)
1695 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1696 if (busiest
< this_rq
) {
1697 spin_unlock(&this_rq
->lock
);
1698 spin_lock(&busiest
->lock
);
1699 spin_lock(&this_rq
->lock
);
1701 spin_lock(&busiest
->lock
);
1706 * If dest_cpu is allowed for this process, migrate the task to it.
1707 * This is accomplished by forcing the cpu_allowed mask to only
1708 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1709 * the cpu_allowed mask is restored.
1711 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1713 migration_req_t req
;
1715 unsigned long flags
;
1717 rq
= task_rq_lock(p
, &flags
);
1718 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1719 || unlikely(cpu_is_offline(dest_cpu
)))
1722 /* force the process onto the specified CPU */
1723 if (migrate_task(p
, dest_cpu
, &req
)) {
1724 /* Need to wait for migration thread (might exit: take ref). */
1725 struct task_struct
*mt
= rq
->migration_thread
;
1726 get_task_struct(mt
);
1727 task_rq_unlock(rq
, &flags
);
1728 wake_up_process(mt
);
1729 put_task_struct(mt
);
1730 wait_for_completion(&req
.done
);
1734 task_rq_unlock(rq
, &flags
);
1738 * sched_exec - execve() is a valuable balancing opportunity, because at
1739 * this point the task has the smallest effective memory and cache footprint.
1741 void sched_exec(void)
1743 int new_cpu
, this_cpu
= get_cpu();
1744 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
1746 if (new_cpu
!= this_cpu
)
1747 sched_migrate_task(current
, new_cpu
);
1751 * pull_task - move a task from a remote runqueue to the local runqueue.
1752 * Both runqueues must be locked.
1755 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1756 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1758 dequeue_task(p
, src_array
);
1759 src_rq
->nr_running
--;
1760 set_task_cpu(p
, this_cpu
);
1761 this_rq
->nr_running
++;
1762 enqueue_task(p
, this_array
);
1763 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1764 + this_rq
->timestamp_last_tick
;
1766 * Note that idle threads have a prio of MAX_PRIO, for this test
1767 * to be always true for them.
1769 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1770 resched_task(this_rq
->curr
);
1774 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1777 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1778 struct sched_domain
*sd
, enum idle_type idle
,
1782 * We do not migrate tasks that are:
1783 * 1) running (obviously), or
1784 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1785 * 3) are cache-hot on their current CPU.
1787 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1791 if (task_running(rq
, p
))
1795 * Aggressive migration if:
1796 * 1) task is cache cold, or
1797 * 2) too many balance attempts have failed.
1800 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1803 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1809 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1810 * as part of a balancing operation within "domain". Returns the number of
1813 * Called with both runqueues locked.
1815 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1816 unsigned long max_nr_move
, struct sched_domain
*sd
,
1817 enum idle_type idle
, int *all_pinned
)
1819 prio_array_t
*array
, *dst_array
;
1820 struct list_head
*head
, *curr
;
1821 int idx
, pulled
= 0, pinned
= 0;
1824 if (max_nr_move
== 0)
1830 * We first consider expired tasks. Those will likely not be
1831 * executed in the near future, and they are most likely to
1832 * be cache-cold, thus switching CPUs has the least effect
1835 if (busiest
->expired
->nr_active
) {
1836 array
= busiest
->expired
;
1837 dst_array
= this_rq
->expired
;
1839 array
= busiest
->active
;
1840 dst_array
= this_rq
->active
;
1844 /* Start searching at priority 0: */
1848 idx
= sched_find_first_bit(array
->bitmap
);
1850 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1851 if (idx
>= MAX_PRIO
) {
1852 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1853 array
= busiest
->active
;
1854 dst_array
= this_rq
->active
;
1860 head
= array
->queue
+ idx
;
1863 tmp
= list_entry(curr
, task_t
, run_list
);
1867 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1874 #ifdef CONFIG_SCHEDSTATS
1875 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1876 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1879 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1882 /* We only want to steal up to the prescribed number of tasks. */
1883 if (pulled
< max_nr_move
) {
1891 * Right now, this is the only place pull_task() is called,
1892 * so we can safely collect pull_task() stats here rather than
1893 * inside pull_task().
1895 schedstat_add(sd
, lb_gained
[idle
], pulled
);
1898 *all_pinned
= pinned
;
1903 * find_busiest_group finds and returns the busiest CPU group within the
1904 * domain. It calculates and returns the number of tasks which should be
1905 * moved to restore balance via the imbalance parameter.
1907 static struct sched_group
*
1908 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
1909 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
)
1911 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1912 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
1913 unsigned long max_pull
;
1916 max_load
= this_load
= total_load
= total_pwr
= 0;
1917 if (idle
== NOT_IDLE
)
1918 load_idx
= sd
->busy_idx
;
1919 else if (idle
== NEWLY_IDLE
)
1920 load_idx
= sd
->newidle_idx
;
1922 load_idx
= sd
->idle_idx
;
1929 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1931 /* Tally up the load of all CPUs in the group */
1934 for_each_cpu_mask(i
, group
->cpumask
) {
1935 if (*sd_idle
&& !idle_cpu(i
))
1938 /* Bias balancing toward cpus of our domain */
1940 load
= target_load(i
, load_idx
);
1942 load
= source_load(i
, load_idx
);
1947 total_load
+= avg_load
;
1948 total_pwr
+= group
->cpu_power
;
1950 /* Adjust by relative CPU power of the group */
1951 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1954 this_load
= avg_load
;
1956 } else if (avg_load
> max_load
) {
1957 max_load
= avg_load
;
1960 group
= group
->next
;
1961 } while (group
!= sd
->groups
);
1963 if (!busiest
|| this_load
>= max_load
|| max_load
<= SCHED_LOAD_SCALE
)
1966 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
1968 if (this_load
>= avg_load
||
1969 100*max_load
<= sd
->imbalance_pct
*this_load
)
1973 * We're trying to get all the cpus to the average_load, so we don't
1974 * want to push ourselves above the average load, nor do we wish to
1975 * reduce the max loaded cpu below the average load, as either of these
1976 * actions would just result in more rebalancing later, and ping-pong
1977 * tasks around. Thus we look for the minimum possible imbalance.
1978 * Negative imbalances (*we* are more loaded than anyone else) will
1979 * be counted as no imbalance for these purposes -- we can't fix that
1980 * by pulling tasks to us. Be careful of negative numbers as they'll
1981 * appear as very large values with unsigned longs.
1984 /* Don't want to pull so many tasks that a group would go idle */
1985 max_pull
= min(max_load
- avg_load
, max_load
- SCHED_LOAD_SCALE
);
1987 /* How much load to actually move to equalise the imbalance */
1988 *imbalance
= min(max_pull
* busiest
->cpu_power
,
1989 (avg_load
- this_load
) * this->cpu_power
)
1992 if (*imbalance
< SCHED_LOAD_SCALE
) {
1993 unsigned long pwr_now
= 0, pwr_move
= 0;
1996 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
2002 * OK, we don't have enough imbalance to justify moving tasks,
2003 * however we may be able to increase total CPU power used by
2007 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
2008 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
2009 pwr_now
/= SCHED_LOAD_SCALE
;
2011 /* Amount of load we'd subtract */
2012 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
2014 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
2017 /* Amount of load we'd add */
2018 if (max_load
*busiest
->cpu_power
<
2019 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
2020 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
2022 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
2023 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
2024 pwr_move
/= SCHED_LOAD_SCALE
;
2026 /* Move if we gain throughput */
2027 if (pwr_move
<= pwr_now
)
2034 /* Get rid of the scaling factor, rounding down as we divide */
2035 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
2045 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2047 static runqueue_t
*find_busiest_queue(struct sched_group
*group
)
2049 unsigned long load
, max_load
= 0;
2050 runqueue_t
*busiest
= NULL
;
2053 for_each_cpu_mask(i
, group
->cpumask
) {
2054 load
= source_load(i
, 0);
2056 if (load
> max_load
) {
2058 busiest
= cpu_rq(i
);
2066 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2067 * so long as it is large enough.
2069 #define MAX_PINNED_INTERVAL 512
2072 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2073 * tasks if there is an imbalance.
2075 * Called with this_rq unlocked.
2077 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
2078 struct sched_domain
*sd
, enum idle_type idle
)
2080 struct sched_group
*group
;
2081 runqueue_t
*busiest
;
2082 unsigned long imbalance
;
2083 int nr_moved
, all_pinned
= 0;
2084 int active_balance
= 0;
2087 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2090 schedstat_inc(sd
, lb_cnt
[idle
]);
2092 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
);
2094 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2098 busiest
= find_busiest_queue(group
);
2100 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2104 BUG_ON(busiest
== this_rq
);
2106 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2109 if (busiest
->nr_running
> 1) {
2111 * Attempt to move tasks. If find_busiest_group has found
2112 * an imbalance but busiest->nr_running <= 1, the group is
2113 * still unbalanced. nr_moved simply stays zero, so it is
2114 * correctly treated as an imbalance.
2116 double_rq_lock(this_rq
, busiest
);
2117 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2118 imbalance
, sd
, idle
, &all_pinned
);
2119 double_rq_unlock(this_rq
, busiest
);
2121 /* All tasks on this runqueue were pinned by CPU affinity */
2122 if (unlikely(all_pinned
))
2127 schedstat_inc(sd
, lb_failed
[idle
]);
2128 sd
->nr_balance_failed
++;
2130 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2132 spin_lock(&busiest
->lock
);
2134 /* don't kick the migration_thread, if the curr
2135 * task on busiest cpu can't be moved to this_cpu
2137 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2138 spin_unlock(&busiest
->lock
);
2140 goto out_one_pinned
;
2143 if (!busiest
->active_balance
) {
2144 busiest
->active_balance
= 1;
2145 busiest
->push_cpu
= this_cpu
;
2148 spin_unlock(&busiest
->lock
);
2150 wake_up_process(busiest
->migration_thread
);
2153 * We've kicked active balancing, reset the failure
2156 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2159 sd
->nr_balance_failed
= 0;
2161 if (likely(!active_balance
)) {
2162 /* We were unbalanced, so reset the balancing interval */
2163 sd
->balance_interval
= sd
->min_interval
;
2166 * If we've begun active balancing, start to back off. This
2167 * case may not be covered by the all_pinned logic if there
2168 * is only 1 task on the busy runqueue (because we don't call
2171 if (sd
->balance_interval
< sd
->max_interval
)
2172 sd
->balance_interval
*= 2;
2175 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2180 schedstat_inc(sd
, lb_balanced
[idle
]);
2182 sd
->nr_balance_failed
= 0;
2185 /* tune up the balancing interval */
2186 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2187 (sd
->balance_interval
< sd
->max_interval
))
2188 sd
->balance_interval
*= 2;
2190 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2196 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2197 * tasks if there is an imbalance.
2199 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2200 * this_rq is locked.
2202 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2203 struct sched_domain
*sd
)
2205 struct sched_group
*group
;
2206 runqueue_t
*busiest
= NULL
;
2207 unsigned long imbalance
;
2211 if (sd
->flags
& SD_SHARE_CPUPOWER
)
2214 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2215 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
, &sd_idle
);
2217 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2221 busiest
= find_busiest_queue(group
);
2223 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2227 BUG_ON(busiest
== this_rq
);
2229 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2232 if (busiest
->nr_running
> 1) {
2233 /* Attempt to move tasks */
2234 double_lock_balance(this_rq
, busiest
);
2235 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2236 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2237 spin_unlock(&busiest
->lock
);
2241 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2242 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2245 sd
->nr_balance_failed
= 0;
2250 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2251 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2253 sd
->nr_balance_failed
= 0;
2258 * idle_balance is called by schedule() if this_cpu is about to become
2259 * idle. Attempts to pull tasks from other CPUs.
2261 static inline void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2263 struct sched_domain
*sd
;
2265 for_each_domain(this_cpu
, sd
) {
2266 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2267 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2268 /* We've pulled tasks over so stop searching */
2276 * active_load_balance is run by migration threads. It pushes running tasks
2277 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2278 * running on each physical CPU where possible, and avoids physical /
2279 * logical imbalances.
2281 * Called with busiest_rq locked.
2283 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2285 struct sched_domain
*sd
;
2286 runqueue_t
*target_rq
;
2287 int target_cpu
= busiest_rq
->push_cpu
;
2289 if (busiest_rq
->nr_running
<= 1)
2290 /* no task to move */
2293 target_rq
= cpu_rq(target_cpu
);
2296 * This condition is "impossible", if it occurs
2297 * we need to fix it. Originally reported by
2298 * Bjorn Helgaas on a 128-cpu setup.
2300 BUG_ON(busiest_rq
== target_rq
);
2302 /* move a task from busiest_rq to target_rq */
2303 double_lock_balance(busiest_rq
, target_rq
);
2305 /* Search for an sd spanning us and the target CPU. */
2306 for_each_domain(target_cpu
, sd
)
2307 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2308 cpu_isset(busiest_cpu
, sd
->span
))
2311 if (unlikely(sd
== NULL
))
2314 schedstat_inc(sd
, alb_cnt
);
2316 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1, sd
, SCHED_IDLE
, NULL
))
2317 schedstat_inc(sd
, alb_pushed
);
2319 schedstat_inc(sd
, alb_failed
);
2321 spin_unlock(&target_rq
->lock
);
2325 * rebalance_tick will get called every timer tick, on every CPU.
2327 * It checks each scheduling domain to see if it is due to be balanced,
2328 * and initiates a balancing operation if so.
2330 * Balancing parameters are set up in arch_init_sched_domains.
2333 /* Don't have all balancing operations going off at once */
2334 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2336 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2337 enum idle_type idle
)
2339 unsigned long old_load
, this_load
;
2340 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2341 struct sched_domain
*sd
;
2344 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2345 /* Update our load */
2346 for (i
= 0; i
< 3; i
++) {
2347 unsigned long new_load
= this_load
;
2349 old_load
= this_rq
->cpu_load
[i
];
2351 * Round up the averaging division if load is increasing. This
2352 * prevents us from getting stuck on 9 if the load is 10, for
2355 if (new_load
> old_load
)
2356 new_load
+= scale
-1;
2357 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2360 for_each_domain(this_cpu
, sd
) {
2361 unsigned long interval
;
2363 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2366 interval
= sd
->balance_interval
;
2367 if (idle
!= SCHED_IDLE
)
2368 interval
*= sd
->busy_factor
;
2370 /* scale ms to jiffies */
2371 interval
= msecs_to_jiffies(interval
);
2372 if (unlikely(!interval
))
2375 if (j
- sd
->last_balance
>= interval
) {
2376 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2378 * We've pulled tasks over so either we're no
2379 * longer idle, or one of our SMT siblings is
2384 sd
->last_balance
+= interval
;
2390 * on UP we do not need to balance between CPUs:
2392 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2395 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2400 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2403 #ifdef CONFIG_SCHED_SMT
2404 spin_lock(&rq
->lock
);
2406 * If an SMT sibling task has been put to sleep for priority
2407 * reasons reschedule the idle task to see if it can now run.
2409 if (rq
->nr_running
) {
2410 resched_task(rq
->idle
);
2413 spin_unlock(&rq
->lock
);
2418 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2420 EXPORT_PER_CPU_SYMBOL(kstat
);
2423 * This is called on clock ticks and on context switches.
2424 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2426 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2427 unsigned long long now
)
2429 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2430 p
->sched_time
+= now
- last
;
2434 * Return current->sched_time plus any more ns on the sched_clock
2435 * that have not yet been banked.
2437 unsigned long long current_sched_time(const task_t
*tsk
)
2439 unsigned long long ns
;
2440 unsigned long flags
;
2441 local_irq_save(flags
);
2442 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2443 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2444 local_irq_restore(flags
);
2449 * We place interactive tasks back into the active array, if possible.
2451 * To guarantee that this does not starve expired tasks we ignore the
2452 * interactivity of a task if the first expired task had to wait more
2453 * than a 'reasonable' amount of time. This deadline timeout is
2454 * load-dependent, as the frequency of array switched decreases with
2455 * increasing number of running tasks. We also ignore the interactivity
2456 * if a better static_prio task has expired:
2458 #define EXPIRED_STARVING(rq) \
2459 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2460 (jiffies - (rq)->expired_timestamp >= \
2461 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2462 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2465 * Account user cpu time to a process.
2466 * @p: the process that the cpu time gets accounted to
2467 * @hardirq_offset: the offset to subtract from hardirq_count()
2468 * @cputime: the cpu time spent in user space since the last update
2470 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2472 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2475 p
->utime
= cputime_add(p
->utime
, cputime
);
2477 /* Add user time to cpustat. */
2478 tmp
= cputime_to_cputime64(cputime
);
2479 if (TASK_NICE(p
) > 0)
2480 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2482 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2486 * Account system cpu time to a process.
2487 * @p: the process that the cpu time gets accounted to
2488 * @hardirq_offset: the offset to subtract from hardirq_count()
2489 * @cputime: the cpu time spent in kernel space since the last update
2491 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2494 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2495 runqueue_t
*rq
= this_rq();
2498 p
->stime
= cputime_add(p
->stime
, cputime
);
2500 /* Add system time to cpustat. */
2501 tmp
= cputime_to_cputime64(cputime
);
2502 if (hardirq_count() - hardirq_offset
)
2503 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2504 else if (softirq_count())
2505 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2506 else if (p
!= rq
->idle
)
2507 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2508 else if (atomic_read(&rq
->nr_iowait
) > 0)
2509 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2511 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2512 /* Account for system time used */
2513 acct_update_integrals(p
);
2517 * Account for involuntary wait time.
2518 * @p: the process from which the cpu time has been stolen
2519 * @steal: the cpu time spent in involuntary wait
2521 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2523 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2524 cputime64_t tmp
= cputime_to_cputime64(steal
);
2525 runqueue_t
*rq
= this_rq();
2527 if (p
== rq
->idle
) {
2528 p
->stime
= cputime_add(p
->stime
, steal
);
2529 if (atomic_read(&rq
->nr_iowait
) > 0)
2530 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2532 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2534 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2538 * This function gets called by the timer code, with HZ frequency.
2539 * We call it with interrupts disabled.
2541 * It also gets called by the fork code, when changing the parent's
2544 void scheduler_tick(void)
2546 int cpu
= smp_processor_id();
2547 runqueue_t
*rq
= this_rq();
2548 task_t
*p
= current
;
2549 unsigned long long now
= sched_clock();
2551 update_cpu_clock(p
, rq
, now
);
2553 rq
->timestamp_last_tick
= now
;
2555 if (p
== rq
->idle
) {
2556 if (wake_priority_sleeper(rq
))
2558 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2562 /* Task might have expired already, but not scheduled off yet */
2563 if (p
->array
!= rq
->active
) {
2564 set_tsk_need_resched(p
);
2567 spin_lock(&rq
->lock
);
2569 * The task was running during this tick - update the
2570 * time slice counter. Note: we do not update a thread's
2571 * priority until it either goes to sleep or uses up its
2572 * timeslice. This makes it possible for interactive tasks
2573 * to use up their timeslices at their highest priority levels.
2577 * RR tasks need a special form of timeslice management.
2578 * FIFO tasks have no timeslices.
2580 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2581 p
->time_slice
= task_timeslice(p
);
2582 p
->first_time_slice
= 0;
2583 set_tsk_need_resched(p
);
2585 /* put it at the end of the queue: */
2586 requeue_task(p
, rq
->active
);
2590 if (!--p
->time_slice
) {
2591 dequeue_task(p
, rq
->active
);
2592 set_tsk_need_resched(p
);
2593 p
->prio
= effective_prio(p
);
2594 p
->time_slice
= task_timeslice(p
);
2595 p
->first_time_slice
= 0;
2597 if (!rq
->expired_timestamp
)
2598 rq
->expired_timestamp
= jiffies
;
2599 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2600 enqueue_task(p
, rq
->expired
);
2601 if (p
->static_prio
< rq
->best_expired_prio
)
2602 rq
->best_expired_prio
= p
->static_prio
;
2604 enqueue_task(p
, rq
->active
);
2607 * Prevent a too long timeslice allowing a task to monopolize
2608 * the CPU. We do this by splitting up the timeslice into
2611 * Note: this does not mean the task's timeslices expire or
2612 * get lost in any way, they just might be preempted by
2613 * another task of equal priority. (one with higher
2614 * priority would have preempted this task already.) We
2615 * requeue this task to the end of the list on this priority
2616 * level, which is in essence a round-robin of tasks with
2619 * This only applies to tasks in the interactive
2620 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2622 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2623 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2624 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2625 (p
->array
== rq
->active
)) {
2627 requeue_task(p
, rq
->active
);
2628 set_tsk_need_resched(p
);
2632 spin_unlock(&rq
->lock
);
2634 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2637 #ifdef CONFIG_SCHED_SMT
2638 static inline void wakeup_busy_runqueue(runqueue_t
*rq
)
2640 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
2641 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
2642 resched_task(rq
->idle
);
2645 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2647 struct sched_domain
*tmp
, *sd
= NULL
;
2648 cpumask_t sibling_map
;
2651 for_each_domain(this_cpu
, tmp
)
2652 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2659 * Unlock the current runqueue because we have to lock in
2660 * CPU order to avoid deadlocks. Caller knows that we might
2661 * unlock. We keep IRQs disabled.
2663 spin_unlock(&this_rq
->lock
);
2665 sibling_map
= sd
->span
;
2667 for_each_cpu_mask(i
, sibling_map
)
2668 spin_lock(&cpu_rq(i
)->lock
);
2670 * We clear this CPU from the mask. This both simplifies the
2671 * inner loop and keps this_rq locked when we exit:
2673 cpu_clear(this_cpu
, sibling_map
);
2675 for_each_cpu_mask(i
, sibling_map
) {
2676 runqueue_t
*smt_rq
= cpu_rq(i
);
2678 wakeup_busy_runqueue(smt_rq
);
2681 for_each_cpu_mask(i
, sibling_map
)
2682 spin_unlock(&cpu_rq(i
)->lock
);
2684 * We exit with this_cpu's rq still held and IRQs
2690 * number of 'lost' timeslices this task wont be able to fully
2691 * utilize, if another task runs on a sibling. This models the
2692 * slowdown effect of other tasks running on siblings:
2694 static inline unsigned long smt_slice(task_t
*p
, struct sched_domain
*sd
)
2696 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
2699 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2701 struct sched_domain
*tmp
, *sd
= NULL
;
2702 cpumask_t sibling_map
;
2703 prio_array_t
*array
;
2707 for_each_domain(this_cpu
, tmp
)
2708 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2715 * The same locking rules and details apply as for
2716 * wake_sleeping_dependent():
2718 spin_unlock(&this_rq
->lock
);
2719 sibling_map
= sd
->span
;
2720 for_each_cpu_mask(i
, sibling_map
)
2721 spin_lock(&cpu_rq(i
)->lock
);
2722 cpu_clear(this_cpu
, sibling_map
);
2725 * Establish next task to be run - it might have gone away because
2726 * we released the runqueue lock above:
2728 if (!this_rq
->nr_running
)
2730 array
= this_rq
->active
;
2731 if (!array
->nr_active
)
2732 array
= this_rq
->expired
;
2733 BUG_ON(!array
->nr_active
);
2735 p
= list_entry(array
->queue
[sched_find_first_bit(array
->bitmap
)].next
,
2738 for_each_cpu_mask(i
, sibling_map
) {
2739 runqueue_t
*smt_rq
= cpu_rq(i
);
2740 task_t
*smt_curr
= smt_rq
->curr
;
2742 /* Kernel threads do not participate in dependent sleeping */
2743 if (!p
->mm
|| !smt_curr
->mm
|| rt_task(p
))
2744 goto check_smt_task
;
2747 * If a user task with lower static priority than the
2748 * running task on the SMT sibling is trying to schedule,
2749 * delay it till there is proportionately less timeslice
2750 * left of the sibling task to prevent a lower priority
2751 * task from using an unfair proportion of the
2752 * physical cpu's resources. -ck
2754 if (rt_task(smt_curr
)) {
2756 * With real time tasks we run non-rt tasks only
2757 * per_cpu_gain% of the time.
2759 if ((jiffies
% DEF_TIMESLICE
) >
2760 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2763 if (smt_curr
->static_prio
< p
->static_prio
&&
2764 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2765 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
2769 if ((!smt_curr
->mm
&& smt_curr
!= smt_rq
->idle
) ||
2773 wakeup_busy_runqueue(smt_rq
);
2778 * Reschedule a lower priority task on the SMT sibling for
2779 * it to be put to sleep, or wake it up if it has been put to
2780 * sleep for priority reasons to see if it should run now.
2783 if ((jiffies
% DEF_TIMESLICE
) >
2784 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2785 resched_task(smt_curr
);
2787 if (TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2788 smt_slice(p
, sd
) > task_timeslice(smt_curr
))
2789 resched_task(smt_curr
);
2791 wakeup_busy_runqueue(smt_rq
);
2795 for_each_cpu_mask(i
, sibling_map
)
2796 spin_unlock(&cpu_rq(i
)->lock
);
2800 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2804 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2810 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2812 void fastcall
add_preempt_count(int val
)
2817 BUG_ON((preempt_count() < 0));
2818 preempt_count() += val
;
2820 * Spinlock count overflowing soon?
2822 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2824 EXPORT_SYMBOL(add_preempt_count
);
2826 void fastcall
sub_preempt_count(int val
)
2831 BUG_ON(val
> preempt_count());
2833 * Is the spinlock portion underflowing?
2835 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2836 preempt_count() -= val
;
2838 EXPORT_SYMBOL(sub_preempt_count
);
2843 * schedule() is the main scheduler function.
2845 asmlinkage
void __sched
schedule(void)
2848 task_t
*prev
, *next
;
2850 prio_array_t
*array
;
2851 struct list_head
*queue
;
2852 unsigned long long now
;
2853 unsigned long run_time
;
2854 int cpu
, idx
, new_prio
;
2857 * Test if we are atomic. Since do_exit() needs to call into
2858 * schedule() atomically, we ignore that path for now.
2859 * Otherwise, whine if we are scheduling when we should not be.
2861 if (likely(!current
->exit_state
)) {
2862 if (unlikely(in_atomic())) {
2863 printk(KERN_ERR
"scheduling while atomic: "
2865 current
->comm
, preempt_count(), current
->pid
);
2869 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2874 release_kernel_lock(prev
);
2875 need_resched_nonpreemptible
:
2879 * The idle thread is not allowed to schedule!
2880 * Remove this check after it has been exercised a bit.
2882 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2883 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
2887 schedstat_inc(rq
, sched_cnt
);
2888 now
= sched_clock();
2889 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
2890 run_time
= now
- prev
->timestamp
;
2891 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
2894 run_time
= NS_MAX_SLEEP_AVG
;
2897 * Tasks charged proportionately less run_time at high sleep_avg to
2898 * delay them losing their interactive status
2900 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
2902 spin_lock_irq(&rq
->lock
);
2904 if (unlikely(prev
->flags
& PF_DEAD
))
2905 prev
->state
= EXIT_DEAD
;
2907 switch_count
= &prev
->nivcsw
;
2908 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2909 switch_count
= &prev
->nvcsw
;
2910 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
2911 unlikely(signal_pending(prev
))))
2912 prev
->state
= TASK_RUNNING
;
2914 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
2915 rq
->nr_uninterruptible
++;
2916 deactivate_task(prev
, rq
);
2920 cpu
= smp_processor_id();
2921 if (unlikely(!rq
->nr_running
)) {
2923 idle_balance(cpu
, rq
);
2924 if (!rq
->nr_running
) {
2926 rq
->expired_timestamp
= 0;
2927 wake_sleeping_dependent(cpu
, rq
);
2929 * wake_sleeping_dependent() might have released
2930 * the runqueue, so break out if we got new
2933 if (!rq
->nr_running
)
2937 if (dependent_sleeper(cpu
, rq
)) {
2942 * dependent_sleeper() releases and reacquires the runqueue
2943 * lock, hence go into the idle loop if the rq went
2946 if (unlikely(!rq
->nr_running
))
2951 if (unlikely(!array
->nr_active
)) {
2953 * Switch the active and expired arrays.
2955 schedstat_inc(rq
, sched_switch
);
2956 rq
->active
= rq
->expired
;
2957 rq
->expired
= array
;
2959 rq
->expired_timestamp
= 0;
2960 rq
->best_expired_prio
= MAX_PRIO
;
2963 idx
= sched_find_first_bit(array
->bitmap
);
2964 queue
= array
->queue
+ idx
;
2965 next
= list_entry(queue
->next
, task_t
, run_list
);
2967 if (!rt_task(next
) && next
->activated
> 0) {
2968 unsigned long long delta
= now
- next
->timestamp
;
2969 if (unlikely((long long)(now
- next
->timestamp
) < 0))
2972 if (next
->activated
== 1)
2973 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
2975 array
= next
->array
;
2976 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
2978 if (unlikely(next
->prio
!= new_prio
)) {
2979 dequeue_task(next
, array
);
2980 next
->prio
= new_prio
;
2981 enqueue_task(next
, array
);
2983 requeue_task(next
, array
);
2985 next
->activated
= 0;
2987 if (next
== rq
->idle
)
2988 schedstat_inc(rq
, sched_goidle
);
2990 prefetch_stack(next
);
2991 clear_tsk_need_resched(prev
);
2992 rcu_qsctr_inc(task_cpu(prev
));
2994 update_cpu_clock(prev
, rq
, now
);
2996 prev
->sleep_avg
-= run_time
;
2997 if ((long)prev
->sleep_avg
<= 0)
2998 prev
->sleep_avg
= 0;
2999 prev
->timestamp
= prev
->last_ran
= now
;
3001 sched_info_switch(prev
, next
);
3002 if (likely(prev
!= next
)) {
3003 next
->timestamp
= now
;
3008 prepare_task_switch(rq
, next
);
3009 prev
= context_switch(rq
, prev
, next
);
3012 * this_rq must be evaluated again because prev may have moved
3013 * CPUs since it called schedule(), thus the 'rq' on its stack
3014 * frame will be invalid.
3016 finish_task_switch(this_rq(), prev
);
3018 spin_unlock_irq(&rq
->lock
);
3021 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3022 goto need_resched_nonpreemptible
;
3023 preempt_enable_no_resched();
3024 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3028 EXPORT_SYMBOL(schedule
);
3030 #ifdef CONFIG_PREEMPT
3032 * this is is the entry point to schedule() from in-kernel preemption
3033 * off of preempt_enable. Kernel preemptions off return from interrupt
3034 * occur there and call schedule directly.
3036 asmlinkage
void __sched
preempt_schedule(void)
3038 struct thread_info
*ti
= current_thread_info();
3039 #ifdef CONFIG_PREEMPT_BKL
3040 struct task_struct
*task
= current
;
3041 int saved_lock_depth
;
3044 * If there is a non-zero preempt_count or interrupts are disabled,
3045 * we do not want to preempt the current task. Just return..
3047 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
3051 add_preempt_count(PREEMPT_ACTIVE
);
3053 * We keep the big kernel semaphore locked, but we
3054 * clear ->lock_depth so that schedule() doesnt
3055 * auto-release the semaphore:
3057 #ifdef CONFIG_PREEMPT_BKL
3058 saved_lock_depth
= task
->lock_depth
;
3059 task
->lock_depth
= -1;
3062 #ifdef CONFIG_PREEMPT_BKL
3063 task
->lock_depth
= saved_lock_depth
;
3065 sub_preempt_count(PREEMPT_ACTIVE
);
3067 /* we could miss a preemption opportunity between schedule and now */
3069 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3073 EXPORT_SYMBOL(preempt_schedule
);
3076 * this is is the entry point to schedule() from kernel preemption
3077 * off of irq context.
3078 * Note, that this is called and return with irqs disabled. This will
3079 * protect us against recursive calling from irq.
3081 asmlinkage
void __sched
preempt_schedule_irq(void)
3083 struct thread_info
*ti
= current_thread_info();
3084 #ifdef CONFIG_PREEMPT_BKL
3085 struct task_struct
*task
= current
;
3086 int saved_lock_depth
;
3088 /* Catch callers which need to be fixed*/
3089 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3092 add_preempt_count(PREEMPT_ACTIVE
);
3094 * We keep the big kernel semaphore locked, but we
3095 * clear ->lock_depth so that schedule() doesnt
3096 * auto-release the semaphore:
3098 #ifdef CONFIG_PREEMPT_BKL
3099 saved_lock_depth
= task
->lock_depth
;
3100 task
->lock_depth
= -1;
3104 local_irq_disable();
3105 #ifdef CONFIG_PREEMPT_BKL
3106 task
->lock_depth
= saved_lock_depth
;
3108 sub_preempt_count(PREEMPT_ACTIVE
);
3110 /* we could miss a preemption opportunity between schedule and now */
3112 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3116 #endif /* CONFIG_PREEMPT */
3118 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3121 task_t
*p
= curr
->private;
3122 return try_to_wake_up(p
, mode
, sync
);
3125 EXPORT_SYMBOL(default_wake_function
);
3128 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3129 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3130 * number) then we wake all the non-exclusive tasks and one exclusive task.
3132 * There are circumstances in which we can try to wake a task which has already
3133 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3134 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3136 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3137 int nr_exclusive
, int sync
, void *key
)
3139 struct list_head
*tmp
, *next
;
3141 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3144 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3145 flags
= curr
->flags
;
3146 if (curr
->func(curr
, mode
, sync
, key
) &&
3147 (flags
& WQ_FLAG_EXCLUSIVE
) &&
3154 * __wake_up - wake up threads blocked on a waitqueue.
3156 * @mode: which threads
3157 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3158 * @key: is directly passed to the wakeup function
3160 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3161 int nr_exclusive
, void *key
)
3163 unsigned long flags
;
3165 spin_lock_irqsave(&q
->lock
, flags
);
3166 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3167 spin_unlock_irqrestore(&q
->lock
, flags
);
3170 EXPORT_SYMBOL(__wake_up
);
3173 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3175 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3177 __wake_up_common(q
, mode
, 1, 0, NULL
);
3181 * __wake_up_sync - wake up threads blocked on a waitqueue.
3183 * @mode: which threads
3184 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3186 * The sync wakeup differs that the waker knows that it will schedule
3187 * away soon, so while the target thread will be woken up, it will not
3188 * be migrated to another CPU - ie. the two threads are 'synchronized'
3189 * with each other. This can prevent needless bouncing between CPUs.
3191 * On UP it can prevent extra preemption.
3194 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3196 unsigned long flags
;
3202 if (unlikely(!nr_exclusive
))
3205 spin_lock_irqsave(&q
->lock
, flags
);
3206 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3207 spin_unlock_irqrestore(&q
->lock
, flags
);
3209 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3211 void fastcall
complete(struct completion
*x
)
3213 unsigned long flags
;
3215 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3217 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3219 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3221 EXPORT_SYMBOL(complete
);
3223 void fastcall
complete_all(struct completion
*x
)
3225 unsigned long flags
;
3227 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3228 x
->done
+= UINT_MAX
/2;
3229 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3231 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3233 EXPORT_SYMBOL(complete_all
);
3235 void fastcall __sched
wait_for_completion(struct completion
*x
)
3238 spin_lock_irq(&x
->wait
.lock
);
3240 DECLARE_WAITQUEUE(wait
, current
);
3242 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3243 __add_wait_queue_tail(&x
->wait
, &wait
);
3245 __set_current_state(TASK_UNINTERRUPTIBLE
);
3246 spin_unlock_irq(&x
->wait
.lock
);
3248 spin_lock_irq(&x
->wait
.lock
);
3250 __remove_wait_queue(&x
->wait
, &wait
);
3253 spin_unlock_irq(&x
->wait
.lock
);
3255 EXPORT_SYMBOL(wait_for_completion
);
3257 unsigned long fastcall __sched
3258 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3262 spin_lock_irq(&x
->wait
.lock
);
3264 DECLARE_WAITQUEUE(wait
, current
);
3266 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3267 __add_wait_queue_tail(&x
->wait
, &wait
);
3269 __set_current_state(TASK_UNINTERRUPTIBLE
);
3270 spin_unlock_irq(&x
->wait
.lock
);
3271 timeout
= schedule_timeout(timeout
);
3272 spin_lock_irq(&x
->wait
.lock
);
3274 __remove_wait_queue(&x
->wait
, &wait
);
3278 __remove_wait_queue(&x
->wait
, &wait
);
3282 spin_unlock_irq(&x
->wait
.lock
);
3285 EXPORT_SYMBOL(wait_for_completion_timeout
);
3287 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3293 spin_lock_irq(&x
->wait
.lock
);
3295 DECLARE_WAITQUEUE(wait
, current
);
3297 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3298 __add_wait_queue_tail(&x
->wait
, &wait
);
3300 if (signal_pending(current
)) {
3302 __remove_wait_queue(&x
->wait
, &wait
);
3305 __set_current_state(TASK_INTERRUPTIBLE
);
3306 spin_unlock_irq(&x
->wait
.lock
);
3308 spin_lock_irq(&x
->wait
.lock
);
3310 __remove_wait_queue(&x
->wait
, &wait
);
3314 spin_unlock_irq(&x
->wait
.lock
);
3318 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3320 unsigned long fastcall __sched
3321 wait_for_completion_interruptible_timeout(struct completion
*x
,
3322 unsigned long timeout
)
3326 spin_lock_irq(&x
->wait
.lock
);
3328 DECLARE_WAITQUEUE(wait
, current
);
3330 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3331 __add_wait_queue_tail(&x
->wait
, &wait
);
3333 if (signal_pending(current
)) {
3334 timeout
= -ERESTARTSYS
;
3335 __remove_wait_queue(&x
->wait
, &wait
);
3338 __set_current_state(TASK_INTERRUPTIBLE
);
3339 spin_unlock_irq(&x
->wait
.lock
);
3340 timeout
= schedule_timeout(timeout
);
3341 spin_lock_irq(&x
->wait
.lock
);
3343 __remove_wait_queue(&x
->wait
, &wait
);
3347 __remove_wait_queue(&x
->wait
, &wait
);
3351 spin_unlock_irq(&x
->wait
.lock
);
3354 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3357 #define SLEEP_ON_VAR \
3358 unsigned long flags; \
3359 wait_queue_t wait; \
3360 init_waitqueue_entry(&wait, current);
3362 #define SLEEP_ON_HEAD \
3363 spin_lock_irqsave(&q->lock,flags); \
3364 __add_wait_queue(q, &wait); \
3365 spin_unlock(&q->lock);
3367 #define SLEEP_ON_TAIL \
3368 spin_lock_irq(&q->lock); \
3369 __remove_wait_queue(q, &wait); \
3370 spin_unlock_irqrestore(&q->lock, flags);
3372 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3376 current
->state
= TASK_INTERRUPTIBLE
;
3383 EXPORT_SYMBOL(interruptible_sleep_on
);
3385 long fastcall __sched
3386 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3390 current
->state
= TASK_INTERRUPTIBLE
;
3393 timeout
= schedule_timeout(timeout
);
3399 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3401 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3405 current
->state
= TASK_UNINTERRUPTIBLE
;
3412 EXPORT_SYMBOL(sleep_on
);
3414 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3418 current
->state
= TASK_UNINTERRUPTIBLE
;
3421 timeout
= schedule_timeout(timeout
);
3427 EXPORT_SYMBOL(sleep_on_timeout
);
3429 void set_user_nice(task_t
*p
, long nice
)
3431 unsigned long flags
;
3432 prio_array_t
*array
;
3434 int old_prio
, new_prio
, delta
;
3436 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3439 * We have to be careful, if called from sys_setpriority(),
3440 * the task might be in the middle of scheduling on another CPU.
3442 rq
= task_rq_lock(p
, &flags
);
3444 * The RT priorities are set via sched_setscheduler(), but we still
3445 * allow the 'normal' nice value to be set - but as expected
3446 * it wont have any effect on scheduling until the task is
3450 p
->static_prio
= NICE_TO_PRIO(nice
);
3455 dequeue_task(p
, array
);
3458 new_prio
= NICE_TO_PRIO(nice
);
3459 delta
= new_prio
- old_prio
;
3460 p
->static_prio
= NICE_TO_PRIO(nice
);
3464 enqueue_task(p
, array
);
3466 * If the task increased its priority or is running and
3467 * lowered its priority, then reschedule its CPU:
3469 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3470 resched_task(rq
->curr
);
3473 task_rq_unlock(rq
, &flags
);
3476 EXPORT_SYMBOL(set_user_nice
);
3479 * can_nice - check if a task can reduce its nice value
3483 int can_nice(const task_t
*p
, const int nice
)
3485 /* convert nice value [19,-20] to rlimit style value [1,40] */
3486 int nice_rlim
= 20 - nice
;
3487 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3488 capable(CAP_SYS_NICE
));
3491 #ifdef __ARCH_WANT_SYS_NICE
3494 * sys_nice - change the priority of the current process.
3495 * @increment: priority increment
3497 * sys_setpriority is a more generic, but much slower function that
3498 * does similar things.
3500 asmlinkage
long sys_nice(int increment
)
3506 * Setpriority might change our priority at the same moment.
3507 * We don't have to worry. Conceptually one call occurs first
3508 * and we have a single winner.
3510 if (increment
< -40)
3515 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3521 if (increment
< 0 && !can_nice(current
, nice
))
3524 retval
= security_task_setnice(current
, nice
);
3528 set_user_nice(current
, nice
);
3535 * task_prio - return the priority value of a given task.
3536 * @p: the task in question.
3538 * This is the priority value as seen by users in /proc.
3539 * RT tasks are offset by -200. Normal tasks are centered
3540 * around 0, value goes from -16 to +15.
3542 int task_prio(const task_t
*p
)
3544 return p
->prio
- MAX_RT_PRIO
;
3548 * task_nice - return the nice value of a given task.
3549 * @p: the task in question.
3551 int task_nice(const task_t
*p
)
3553 return TASK_NICE(p
);
3555 EXPORT_SYMBOL_GPL(task_nice
);
3558 * idle_cpu - is a given cpu idle currently?
3559 * @cpu: the processor in question.
3561 int idle_cpu(int cpu
)
3563 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3567 * idle_task - return the idle task for a given cpu.
3568 * @cpu: the processor in question.
3570 task_t
*idle_task(int cpu
)
3572 return cpu_rq(cpu
)->idle
;
3576 * find_process_by_pid - find a process with a matching PID value.
3577 * @pid: the pid in question.
3579 static inline task_t
*find_process_by_pid(pid_t pid
)
3581 return pid
? find_task_by_pid(pid
) : current
;
3584 /* Actually do priority change: must hold rq lock. */
3585 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3589 p
->rt_priority
= prio
;
3590 if (policy
!= SCHED_NORMAL
)
3591 p
->prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
3593 p
->prio
= p
->static_prio
;
3597 * sched_setscheduler - change the scheduling policy and/or RT priority of
3599 * @p: the task in question.
3600 * @policy: new policy.
3601 * @param: structure containing the new RT priority.
3603 int sched_setscheduler(struct task_struct
*p
, int policy
,
3604 struct sched_param
*param
)
3607 int oldprio
, oldpolicy
= -1;
3608 prio_array_t
*array
;
3609 unsigned long flags
;
3613 /* double check policy once rq lock held */
3615 policy
= oldpolicy
= p
->policy
;
3616 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3617 policy
!= SCHED_NORMAL
)
3620 * Valid priorities for SCHED_FIFO and SCHED_RR are
3621 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3623 if (param
->sched_priority
< 0 ||
3624 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3625 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3627 if ((policy
== SCHED_NORMAL
) != (param
->sched_priority
== 0))
3631 * Allow unprivileged RT tasks to decrease priority:
3633 if (!capable(CAP_SYS_NICE
)) {
3634 /* can't change policy */
3635 if (policy
!= p
->policy
&&
3636 !p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3638 /* can't increase priority */
3639 if (policy
!= SCHED_NORMAL
&&
3640 param
->sched_priority
> p
->rt_priority
&&
3641 param
->sched_priority
>
3642 p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3644 /* can't change other user's priorities */
3645 if ((current
->euid
!= p
->euid
) &&
3646 (current
->euid
!= p
->uid
))
3650 retval
= security_task_setscheduler(p
, policy
, param
);
3654 * To be able to change p->policy safely, the apropriate
3655 * runqueue lock must be held.
3657 rq
= task_rq_lock(p
, &flags
);
3658 /* recheck policy now with rq lock held */
3659 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3660 policy
= oldpolicy
= -1;
3661 task_rq_unlock(rq
, &flags
);
3666 deactivate_task(p
, rq
);
3668 __setscheduler(p
, policy
, param
->sched_priority
);
3670 __activate_task(p
, rq
);
3672 * Reschedule if we are currently running on this runqueue and
3673 * our priority decreased, or if we are not currently running on
3674 * this runqueue and our priority is higher than the current's
3676 if (task_running(rq
, p
)) {
3677 if (p
->prio
> oldprio
)
3678 resched_task(rq
->curr
);
3679 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3680 resched_task(rq
->curr
);
3682 task_rq_unlock(rq
, &flags
);
3685 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3688 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3691 struct sched_param lparam
;
3692 struct task_struct
*p
;
3694 if (!param
|| pid
< 0)
3696 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3698 read_lock_irq(&tasklist_lock
);
3699 p
= find_process_by_pid(pid
);
3701 read_unlock_irq(&tasklist_lock
);
3704 retval
= sched_setscheduler(p
, policy
, &lparam
);
3705 read_unlock_irq(&tasklist_lock
);
3710 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3711 * @pid: the pid in question.
3712 * @policy: new policy.
3713 * @param: structure containing the new RT priority.
3715 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3716 struct sched_param __user
*param
)
3718 return do_sched_setscheduler(pid
, policy
, param
);
3722 * sys_sched_setparam - set/change the RT priority of a thread
3723 * @pid: the pid in question.
3724 * @param: structure containing the new RT priority.
3726 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3728 return do_sched_setscheduler(pid
, -1, param
);
3732 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3733 * @pid: the pid in question.
3735 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3737 int retval
= -EINVAL
;
3744 read_lock(&tasklist_lock
);
3745 p
= find_process_by_pid(pid
);
3747 retval
= security_task_getscheduler(p
);
3751 read_unlock(&tasklist_lock
);
3758 * sys_sched_getscheduler - get the RT priority of a thread
3759 * @pid: the pid in question.
3760 * @param: structure containing the RT priority.
3762 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3764 struct sched_param lp
;
3765 int retval
= -EINVAL
;
3768 if (!param
|| pid
< 0)
3771 read_lock(&tasklist_lock
);
3772 p
= find_process_by_pid(pid
);
3777 retval
= security_task_getscheduler(p
);
3781 lp
.sched_priority
= p
->rt_priority
;
3782 read_unlock(&tasklist_lock
);
3785 * This one might sleep, we cannot do it with a spinlock held ...
3787 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3793 read_unlock(&tasklist_lock
);
3797 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3801 cpumask_t cpus_allowed
;
3804 read_lock(&tasklist_lock
);
3806 p
= find_process_by_pid(pid
);
3808 read_unlock(&tasklist_lock
);
3809 unlock_cpu_hotplug();
3814 * It is not safe to call set_cpus_allowed with the
3815 * tasklist_lock held. We will bump the task_struct's
3816 * usage count and then drop tasklist_lock.
3819 read_unlock(&tasklist_lock
);
3822 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3823 !capable(CAP_SYS_NICE
))
3826 cpus_allowed
= cpuset_cpus_allowed(p
);
3827 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3828 retval
= set_cpus_allowed(p
, new_mask
);
3832 unlock_cpu_hotplug();
3836 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3837 cpumask_t
*new_mask
)
3839 if (len
< sizeof(cpumask_t
)) {
3840 memset(new_mask
, 0, sizeof(cpumask_t
));
3841 } else if (len
> sizeof(cpumask_t
)) {
3842 len
= sizeof(cpumask_t
);
3844 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3848 * sys_sched_setaffinity - set the cpu affinity of a process
3849 * @pid: pid of the process
3850 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3851 * @user_mask_ptr: user-space pointer to the new cpu mask
3853 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3854 unsigned long __user
*user_mask_ptr
)
3859 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3863 return sched_setaffinity(pid
, new_mask
);
3867 * Represents all cpu's present in the system
3868 * In systems capable of hotplug, this map could dynamically grow
3869 * as new cpu's are detected in the system via any platform specific
3870 * method, such as ACPI for e.g.
3873 cpumask_t cpu_present_map
;
3874 EXPORT_SYMBOL(cpu_present_map
);
3877 cpumask_t cpu_online_map
= CPU_MASK_ALL
;
3878 cpumask_t cpu_possible_map
= CPU_MASK_ALL
;
3881 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
3887 read_lock(&tasklist_lock
);
3890 p
= find_process_by_pid(pid
);
3895 cpus_and(*mask
, p
->cpus_allowed
, cpu_possible_map
);
3898 read_unlock(&tasklist_lock
);
3899 unlock_cpu_hotplug();
3907 * sys_sched_getaffinity - get the cpu affinity of a process
3908 * @pid: pid of the process
3909 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3910 * @user_mask_ptr: user-space pointer to hold the current cpu mask
3912 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
3913 unsigned long __user
*user_mask_ptr
)
3918 if (len
< sizeof(cpumask_t
))
3921 ret
= sched_getaffinity(pid
, &mask
);
3925 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
3928 return sizeof(cpumask_t
);
3932 * sys_sched_yield - yield the current processor to other threads.
3934 * this function yields the current CPU by moving the calling thread
3935 * to the expired array. If there are no other threads running on this
3936 * CPU then this function will return.
3938 asmlinkage
long sys_sched_yield(void)
3940 runqueue_t
*rq
= this_rq_lock();
3941 prio_array_t
*array
= current
->array
;
3942 prio_array_t
*target
= rq
->expired
;
3944 schedstat_inc(rq
, yld_cnt
);
3946 * We implement yielding by moving the task into the expired
3949 * (special rule: RT tasks will just roundrobin in the active
3952 if (rt_task(current
))
3953 target
= rq
->active
;
3955 if (array
->nr_active
== 1) {
3956 schedstat_inc(rq
, yld_act_empty
);
3957 if (!rq
->expired
->nr_active
)
3958 schedstat_inc(rq
, yld_both_empty
);
3959 } else if (!rq
->expired
->nr_active
)
3960 schedstat_inc(rq
, yld_exp_empty
);
3962 if (array
!= target
) {
3963 dequeue_task(current
, array
);
3964 enqueue_task(current
, target
);
3967 * requeue_task is cheaper so perform that if possible.
3969 requeue_task(current
, array
);
3972 * Since we are going to call schedule() anyway, there's
3973 * no need to preempt or enable interrupts:
3975 __release(rq
->lock
);
3976 _raw_spin_unlock(&rq
->lock
);
3977 preempt_enable_no_resched();
3984 static inline void __cond_resched(void)
3987 * The BKS might be reacquired before we have dropped
3988 * PREEMPT_ACTIVE, which could trigger a second
3989 * cond_resched() call.
3991 if (unlikely(preempt_count()))
3994 add_preempt_count(PREEMPT_ACTIVE
);
3996 sub_preempt_count(PREEMPT_ACTIVE
);
3997 } while (need_resched());
4000 int __sched
cond_resched(void)
4002 if (need_resched()) {
4009 EXPORT_SYMBOL(cond_resched
);
4012 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4013 * call schedule, and on return reacquire the lock.
4015 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4016 * operations here to prevent schedule() from being called twice (once via
4017 * spin_unlock(), once by hand).
4019 int cond_resched_lock(spinlock_t
*lock
)
4023 if (need_lockbreak(lock
)) {
4029 if (need_resched()) {
4030 _raw_spin_unlock(lock
);
4031 preempt_enable_no_resched();
4039 EXPORT_SYMBOL(cond_resched_lock
);
4041 int __sched
cond_resched_softirq(void)
4043 BUG_ON(!in_softirq());
4045 if (need_resched()) {
4046 __local_bh_enable();
4054 EXPORT_SYMBOL(cond_resched_softirq
);
4058 * yield - yield the current processor to other threads.
4060 * this is a shortcut for kernel-space yielding - it marks the
4061 * thread runnable and calls sys_sched_yield().
4063 void __sched
yield(void)
4065 set_current_state(TASK_RUNNING
);
4069 EXPORT_SYMBOL(yield
);
4072 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4073 * that process accounting knows that this is a task in IO wait state.
4075 * But don't do that if it is a deliberate, throttling IO wait (this task
4076 * has set its backing_dev_info: the queue against which it should throttle)
4078 void __sched
io_schedule(void)
4080 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4082 atomic_inc(&rq
->nr_iowait
);
4084 atomic_dec(&rq
->nr_iowait
);
4087 EXPORT_SYMBOL(io_schedule
);
4089 long __sched
io_schedule_timeout(long timeout
)
4091 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4094 atomic_inc(&rq
->nr_iowait
);
4095 ret
= schedule_timeout(timeout
);
4096 atomic_dec(&rq
->nr_iowait
);
4101 * sys_sched_get_priority_max - return maximum RT priority.
4102 * @policy: scheduling class.
4104 * this syscall returns the maximum rt_priority that can be used
4105 * by a given scheduling class.
4107 asmlinkage
long sys_sched_get_priority_max(int policy
)
4114 ret
= MAX_USER_RT_PRIO
-1;
4124 * sys_sched_get_priority_min - return minimum RT priority.
4125 * @policy: scheduling class.
4127 * this syscall returns the minimum rt_priority that can be used
4128 * by a given scheduling class.
4130 asmlinkage
long sys_sched_get_priority_min(int policy
)
4146 * sys_sched_rr_get_interval - return the default timeslice of a process.
4147 * @pid: pid of the process.
4148 * @interval: userspace pointer to the timeslice value.
4150 * this syscall writes the default timeslice value of a given process
4151 * into the user-space timespec buffer. A value of '0' means infinity.
4154 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4156 int retval
= -EINVAL
;
4164 read_lock(&tasklist_lock
);
4165 p
= find_process_by_pid(pid
);
4169 retval
= security_task_getscheduler(p
);
4173 jiffies_to_timespec(p
->policy
& SCHED_FIFO
?
4174 0 : task_timeslice(p
), &t
);
4175 read_unlock(&tasklist_lock
);
4176 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4180 read_unlock(&tasklist_lock
);
4184 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4186 if (list_empty(&p
->children
)) return NULL
;
4187 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4190 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4192 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
4193 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4196 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4198 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
4199 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4202 static void show_task(task_t
*p
)
4206 unsigned long free
= 0;
4207 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
4209 printk("%-13.13s ", p
->comm
);
4210 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4211 if (state
< ARRAY_SIZE(stat_nam
))
4212 printk(stat_nam
[state
]);
4215 #if (BITS_PER_LONG == 32)
4216 if (state
== TASK_RUNNING
)
4217 printk(" running ");
4219 printk(" %08lX ", thread_saved_pc(p
));
4221 if (state
== TASK_RUNNING
)
4222 printk(" running task ");
4224 printk(" %016lx ", thread_saved_pc(p
));
4226 #ifdef CONFIG_DEBUG_STACK_USAGE
4228 unsigned long *n
= (unsigned long *) (p
->thread_info
+1);
4231 free
= (unsigned long) n
- (unsigned long)(p
->thread_info
+1);
4234 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4235 if ((relative
= eldest_child(p
)))
4236 printk("%5d ", relative
->pid
);
4239 if ((relative
= younger_sibling(p
)))
4240 printk("%7d", relative
->pid
);
4243 if ((relative
= older_sibling(p
)))
4244 printk(" %5d", relative
->pid
);
4248 printk(" (L-TLB)\n");
4250 printk(" (NOTLB)\n");
4252 if (state
!= TASK_RUNNING
)
4253 show_stack(p
, NULL
);
4256 void show_state(void)
4260 #if (BITS_PER_LONG == 32)
4263 printk(" task PC pid father child younger older\n");
4267 printk(" task PC pid father child younger older\n");
4269 read_lock(&tasklist_lock
);
4270 do_each_thread(g
, p
) {
4272 * reset the NMI-timeout, listing all files on a slow
4273 * console might take alot of time:
4275 touch_nmi_watchdog();
4277 } while_each_thread(g
, p
);
4279 read_unlock(&tasklist_lock
);
4283 * init_idle - set up an idle thread for a given CPU
4284 * @idle: task in question
4285 * @cpu: cpu the idle task belongs to
4287 * NOTE: this function does not set the idle thread's NEED_RESCHED
4288 * flag, to make booting more robust.
4290 void __devinit
init_idle(task_t
*idle
, int cpu
)
4292 runqueue_t
*rq
= cpu_rq(cpu
);
4293 unsigned long flags
;
4295 idle
->sleep_avg
= 0;
4297 idle
->prio
= MAX_PRIO
;
4298 idle
->state
= TASK_RUNNING
;
4299 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4300 set_task_cpu(idle
, cpu
);
4302 spin_lock_irqsave(&rq
->lock
, flags
);
4303 rq
->curr
= rq
->idle
= idle
;
4304 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4307 spin_unlock_irqrestore(&rq
->lock
, flags
);
4309 /* Set the preempt count _outside_ the spinlocks! */
4310 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4311 idle
->thread_info
->preempt_count
= (idle
->lock_depth
>= 0);
4313 idle
->thread_info
->preempt_count
= 0;
4318 * In a system that switches off the HZ timer nohz_cpu_mask
4319 * indicates which cpus entered this state. This is used
4320 * in the rcu update to wait only for active cpus. For system
4321 * which do not switch off the HZ timer nohz_cpu_mask should
4322 * always be CPU_MASK_NONE.
4324 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4328 * This is how migration works:
4330 * 1) we queue a migration_req_t structure in the source CPU's
4331 * runqueue and wake up that CPU's migration thread.
4332 * 2) we down() the locked semaphore => thread blocks.
4333 * 3) migration thread wakes up (implicitly it forces the migrated
4334 * thread off the CPU)
4335 * 4) it gets the migration request and checks whether the migrated
4336 * task is still in the wrong runqueue.
4337 * 5) if it's in the wrong runqueue then the migration thread removes
4338 * it and puts it into the right queue.
4339 * 6) migration thread up()s the semaphore.
4340 * 7) we wake up and the migration is done.
4344 * Change a given task's CPU affinity. Migrate the thread to a
4345 * proper CPU and schedule it away if the CPU it's executing on
4346 * is removed from the allowed bitmask.
4348 * NOTE: the caller must have a valid reference to the task, the
4349 * task must not exit() & deallocate itself prematurely. The
4350 * call is not atomic; no spinlocks may be held.
4352 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4354 unsigned long flags
;
4356 migration_req_t req
;
4359 rq
= task_rq_lock(p
, &flags
);
4360 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4365 p
->cpus_allowed
= new_mask
;
4366 /* Can the task run on the task's current CPU? If so, we're done */
4367 if (cpu_isset(task_cpu(p
), new_mask
))
4370 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4371 /* Need help from migration thread: drop lock and wait. */
4372 task_rq_unlock(rq
, &flags
);
4373 wake_up_process(rq
->migration_thread
);
4374 wait_for_completion(&req
.done
);
4375 tlb_migrate_finish(p
->mm
);
4379 task_rq_unlock(rq
, &flags
);
4383 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4386 * Move (not current) task off this cpu, onto dest cpu. We're doing
4387 * this because either it can't run here any more (set_cpus_allowed()
4388 * away from this CPU, or CPU going down), or because we're
4389 * attempting to rebalance this task on exec (sched_exec).
4391 * So we race with normal scheduler movements, but that's OK, as long
4392 * as the task is no longer on this CPU.
4394 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4396 runqueue_t
*rq_dest
, *rq_src
;
4398 if (unlikely(cpu_is_offline(dest_cpu
)))
4401 rq_src
= cpu_rq(src_cpu
);
4402 rq_dest
= cpu_rq(dest_cpu
);
4404 double_rq_lock(rq_src
, rq_dest
);
4405 /* Already moved. */
4406 if (task_cpu(p
) != src_cpu
)
4408 /* Affinity changed (again). */
4409 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4412 set_task_cpu(p
, dest_cpu
);
4415 * Sync timestamp with rq_dest's before activating.
4416 * The same thing could be achieved by doing this step
4417 * afterwards, and pretending it was a local activate.
4418 * This way is cleaner and logically correct.
4420 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4421 + rq_dest
->timestamp_last_tick
;
4422 deactivate_task(p
, rq_src
);
4423 activate_task(p
, rq_dest
, 0);
4424 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4425 resched_task(rq_dest
->curr
);
4429 double_rq_unlock(rq_src
, rq_dest
);
4433 * migration_thread - this is a highprio system thread that performs
4434 * thread migration by bumping thread off CPU then 'pushing' onto
4437 static int migration_thread(void *data
)
4440 int cpu
= (long)data
;
4443 BUG_ON(rq
->migration_thread
!= current
);
4445 set_current_state(TASK_INTERRUPTIBLE
);
4446 while (!kthread_should_stop()) {
4447 struct list_head
*head
;
4448 migration_req_t
*req
;
4452 spin_lock_irq(&rq
->lock
);
4454 if (cpu_is_offline(cpu
)) {
4455 spin_unlock_irq(&rq
->lock
);
4459 if (rq
->active_balance
) {
4460 active_load_balance(rq
, cpu
);
4461 rq
->active_balance
= 0;
4464 head
= &rq
->migration_queue
;
4466 if (list_empty(head
)) {
4467 spin_unlock_irq(&rq
->lock
);
4469 set_current_state(TASK_INTERRUPTIBLE
);
4472 req
= list_entry(head
->next
, migration_req_t
, list
);
4473 list_del_init(head
->next
);
4475 spin_unlock(&rq
->lock
);
4476 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4479 complete(&req
->done
);
4481 __set_current_state(TASK_RUNNING
);
4485 /* Wait for kthread_stop */
4486 set_current_state(TASK_INTERRUPTIBLE
);
4487 while (!kthread_should_stop()) {
4489 set_current_state(TASK_INTERRUPTIBLE
);
4491 __set_current_state(TASK_RUNNING
);
4495 #ifdef CONFIG_HOTPLUG_CPU
4496 /* Figure out where task on dead CPU should go, use force if neccessary. */
4497 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4503 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4504 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4505 dest_cpu
= any_online_cpu(mask
);
4507 /* On any allowed CPU? */
4508 if (dest_cpu
== NR_CPUS
)
4509 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4511 /* No more Mr. Nice Guy. */
4512 if (dest_cpu
== NR_CPUS
) {
4513 cpus_setall(tsk
->cpus_allowed
);
4514 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4517 * Don't tell them about moving exiting tasks or
4518 * kernel threads (both mm NULL), since they never
4521 if (tsk
->mm
&& printk_ratelimit())
4522 printk(KERN_INFO
"process %d (%s) no "
4523 "longer affine to cpu%d\n",
4524 tsk
->pid
, tsk
->comm
, dead_cpu
);
4526 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4530 * While a dead CPU has no uninterruptible tasks queued at this point,
4531 * it might still have a nonzero ->nr_uninterruptible counter, because
4532 * for performance reasons the counter is not stricly tracking tasks to
4533 * their home CPUs. So we just add the counter to another CPU's counter,
4534 * to keep the global sum constant after CPU-down:
4536 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4538 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4539 unsigned long flags
;
4541 local_irq_save(flags
);
4542 double_rq_lock(rq_src
, rq_dest
);
4543 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4544 rq_src
->nr_uninterruptible
= 0;
4545 double_rq_unlock(rq_src
, rq_dest
);
4546 local_irq_restore(flags
);
4549 /* Run through task list and migrate tasks from the dead cpu. */
4550 static void migrate_live_tasks(int src_cpu
)
4552 struct task_struct
*tsk
, *t
;
4554 write_lock_irq(&tasklist_lock
);
4556 do_each_thread(t
, tsk
) {
4560 if (task_cpu(tsk
) == src_cpu
)
4561 move_task_off_dead_cpu(src_cpu
, tsk
);
4562 } while_each_thread(t
, tsk
);
4564 write_unlock_irq(&tasklist_lock
);
4567 /* Schedules idle task to be the next runnable task on current CPU.
4568 * It does so by boosting its priority to highest possible and adding it to
4569 * the _front_ of runqueue. Used by CPU offline code.
4571 void sched_idle_next(void)
4573 int cpu
= smp_processor_id();
4574 runqueue_t
*rq
= this_rq();
4575 struct task_struct
*p
= rq
->idle
;
4576 unsigned long flags
;
4578 /* cpu has to be offline */
4579 BUG_ON(cpu_online(cpu
));
4581 /* Strictly not necessary since rest of the CPUs are stopped by now
4582 * and interrupts disabled on current cpu.
4584 spin_lock_irqsave(&rq
->lock
, flags
);
4586 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4587 /* Add idle task to _front_ of it's priority queue */
4588 __activate_idle_task(p
, rq
);
4590 spin_unlock_irqrestore(&rq
->lock
, flags
);
4593 /* Ensures that the idle task is using init_mm right before its cpu goes
4596 void idle_task_exit(void)
4598 struct mm_struct
*mm
= current
->active_mm
;
4600 BUG_ON(cpu_online(smp_processor_id()));
4603 switch_mm(mm
, &init_mm
, current
);
4607 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4609 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4611 /* Must be exiting, otherwise would be on tasklist. */
4612 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4614 /* Cannot have done final schedule yet: would have vanished. */
4615 BUG_ON(tsk
->flags
& PF_DEAD
);
4617 get_task_struct(tsk
);
4620 * Drop lock around migration; if someone else moves it,
4621 * that's OK. No task can be added to this CPU, so iteration is
4624 spin_unlock_irq(&rq
->lock
);
4625 move_task_off_dead_cpu(dead_cpu
, tsk
);
4626 spin_lock_irq(&rq
->lock
);
4628 put_task_struct(tsk
);
4631 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4632 static void migrate_dead_tasks(unsigned int dead_cpu
)
4635 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4637 for (arr
= 0; arr
< 2; arr
++) {
4638 for (i
= 0; i
< MAX_PRIO
; i
++) {
4639 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4640 while (!list_empty(list
))
4641 migrate_dead(dead_cpu
,
4642 list_entry(list
->next
, task_t
,
4647 #endif /* CONFIG_HOTPLUG_CPU */
4650 * migration_call - callback that gets triggered when a CPU is added.
4651 * Here we can start up the necessary migration thread for the new CPU.
4653 static int migration_call(struct notifier_block
*nfb
, unsigned long action
,
4656 int cpu
= (long)hcpu
;
4657 struct task_struct
*p
;
4658 struct runqueue
*rq
;
4659 unsigned long flags
;
4662 case CPU_UP_PREPARE
:
4663 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4666 p
->flags
|= PF_NOFREEZE
;
4667 kthread_bind(p
, cpu
);
4668 /* Must be high prio: stop_machine expects to yield to it. */
4669 rq
= task_rq_lock(p
, &flags
);
4670 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4671 task_rq_unlock(rq
, &flags
);
4672 cpu_rq(cpu
)->migration_thread
= p
;
4675 /* Strictly unneccessary, as first user will wake it. */
4676 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4678 #ifdef CONFIG_HOTPLUG_CPU
4679 case CPU_UP_CANCELED
:
4680 /* Unbind it from offline cpu so it can run. Fall thru. */
4681 kthread_bind(cpu_rq(cpu
)->migration_thread
,
4682 any_online_cpu(cpu_online_map
));
4683 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4684 cpu_rq(cpu
)->migration_thread
= NULL
;
4687 migrate_live_tasks(cpu
);
4689 kthread_stop(rq
->migration_thread
);
4690 rq
->migration_thread
= NULL
;
4691 /* Idle task back to normal (off runqueue, low prio) */
4692 rq
= task_rq_lock(rq
->idle
, &flags
);
4693 deactivate_task(rq
->idle
, rq
);
4694 rq
->idle
->static_prio
= MAX_PRIO
;
4695 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4696 migrate_dead_tasks(cpu
);
4697 task_rq_unlock(rq
, &flags
);
4698 migrate_nr_uninterruptible(rq
);
4699 BUG_ON(rq
->nr_running
!= 0);
4701 /* No need to migrate the tasks: it was best-effort if
4702 * they didn't do lock_cpu_hotplug(). Just wake up
4703 * the requestors. */
4704 spin_lock_irq(&rq
->lock
);
4705 while (!list_empty(&rq
->migration_queue
)) {
4706 migration_req_t
*req
;
4707 req
= list_entry(rq
->migration_queue
.next
,
4708 migration_req_t
, list
);
4709 list_del_init(&req
->list
);
4710 complete(&req
->done
);
4712 spin_unlock_irq(&rq
->lock
);
4719 /* Register at highest priority so that task migration (migrate_all_tasks)
4720 * happens before everything else.
4722 static struct notifier_block __devinitdata migration_notifier
= {
4723 .notifier_call
= migration_call
,
4727 int __init
migration_init(void)
4729 void *cpu
= (void *)(long)smp_processor_id();
4730 /* Start one for boot CPU. */
4731 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4732 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4733 register_cpu_notifier(&migration_notifier
);
4739 #undef SCHED_DOMAIN_DEBUG
4740 #ifdef SCHED_DOMAIN_DEBUG
4741 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4746 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4750 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4755 struct sched_group
*group
= sd
->groups
;
4756 cpumask_t groupmask
;
4758 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4759 cpus_clear(groupmask
);
4762 for (i
= 0; i
< level
+ 1; i
++)
4764 printk("domain %d: ", level
);
4766 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4767 printk("does not load-balance\n");
4769 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4773 printk("span %s\n", str
);
4775 if (!cpu_isset(cpu
, sd
->span
))
4776 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4777 if (!cpu_isset(cpu
, group
->cpumask
))
4778 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4781 for (i
= 0; i
< level
+ 2; i
++)
4787 printk(KERN_ERR
"ERROR: group is NULL\n");
4791 if (!group
->cpu_power
) {
4793 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4796 if (!cpus_weight(group
->cpumask
)) {
4798 printk(KERN_ERR
"ERROR: empty group\n");
4801 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4803 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4806 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4808 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4811 group
= group
->next
;
4812 } while (group
!= sd
->groups
);
4815 if (!cpus_equal(sd
->span
, groupmask
))
4816 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4822 if (!cpus_subset(groupmask
, sd
->span
))
4823 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4829 #define sched_domain_debug(sd, cpu) {}
4832 static int sd_degenerate(struct sched_domain
*sd
)
4834 if (cpus_weight(sd
->span
) == 1)
4837 /* Following flags need at least 2 groups */
4838 if (sd
->flags
& (SD_LOAD_BALANCE
|
4839 SD_BALANCE_NEWIDLE
|
4842 if (sd
->groups
!= sd
->groups
->next
)
4846 /* Following flags don't use groups */
4847 if (sd
->flags
& (SD_WAKE_IDLE
|
4855 static int sd_parent_degenerate(struct sched_domain
*sd
,
4856 struct sched_domain
*parent
)
4858 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
4860 if (sd_degenerate(parent
))
4863 if (!cpus_equal(sd
->span
, parent
->span
))
4866 /* Does parent contain flags not in child? */
4867 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
4868 if (cflags
& SD_WAKE_AFFINE
)
4869 pflags
&= ~SD_WAKE_BALANCE
;
4870 /* Flags needing groups don't count if only 1 group in parent */
4871 if (parent
->groups
== parent
->groups
->next
) {
4872 pflags
&= ~(SD_LOAD_BALANCE
|
4873 SD_BALANCE_NEWIDLE
|
4877 if (~cflags
& pflags
)
4884 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4885 * hold the hotplug lock.
4887 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
4889 runqueue_t
*rq
= cpu_rq(cpu
);
4890 struct sched_domain
*tmp
;
4892 /* Remove the sched domains which do not contribute to scheduling. */
4893 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
4894 struct sched_domain
*parent
= tmp
->parent
;
4897 if (sd_parent_degenerate(tmp
, parent
))
4898 tmp
->parent
= parent
->parent
;
4901 if (sd
&& sd_degenerate(sd
))
4904 sched_domain_debug(sd
, cpu
);
4906 rcu_assign_pointer(rq
->sd
, sd
);
4909 /* cpus with isolated domains */
4910 static cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
4912 /* Setup the mask of cpus configured for isolated domains */
4913 static int __init
isolated_cpu_setup(char *str
)
4915 int ints
[NR_CPUS
], i
;
4917 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
4918 cpus_clear(cpu_isolated_map
);
4919 for (i
= 1; i
<= ints
[0]; i
++)
4920 if (ints
[i
] < NR_CPUS
)
4921 cpu_set(ints
[i
], cpu_isolated_map
);
4925 __setup ("isolcpus=", isolated_cpu_setup
);
4928 * init_sched_build_groups takes an array of groups, the cpumask we wish
4929 * to span, and a pointer to a function which identifies what group a CPU
4930 * belongs to. The return value of group_fn must be a valid index into the
4931 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
4932 * keep track of groups covered with a cpumask_t).
4934 * init_sched_build_groups will build a circular linked list of the groups
4935 * covered by the given span, and will set each group's ->cpumask correctly,
4936 * and ->cpu_power to 0.
4938 static void init_sched_build_groups(struct sched_group groups
[], cpumask_t span
,
4939 int (*group_fn
)(int cpu
))
4941 struct sched_group
*first
= NULL
, *last
= NULL
;
4942 cpumask_t covered
= CPU_MASK_NONE
;
4945 for_each_cpu_mask(i
, span
) {
4946 int group
= group_fn(i
);
4947 struct sched_group
*sg
= &groups
[group
];
4950 if (cpu_isset(i
, covered
))
4953 sg
->cpumask
= CPU_MASK_NONE
;
4956 for_each_cpu_mask(j
, span
) {
4957 if (group_fn(j
) != group
)
4960 cpu_set(j
, covered
);
4961 cpu_set(j
, sg
->cpumask
);
4972 #define SD_NODES_PER_DOMAIN 16
4976 * find_next_best_node - find the next node to include in a sched_domain
4977 * @node: node whose sched_domain we're building
4978 * @used_nodes: nodes already in the sched_domain
4980 * Find the next node to include in a given scheduling domain. Simply
4981 * finds the closest node not already in the @used_nodes map.
4983 * Should use nodemask_t.
4985 static int find_next_best_node(int node
, unsigned long *used_nodes
)
4987 int i
, n
, val
, min_val
, best_node
= 0;
4991 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
4992 /* Start at @node */
4993 n
= (node
+ i
) % MAX_NUMNODES
;
4995 if (!nr_cpus_node(n
))
4998 /* Skip already used nodes */
4999 if (test_bit(n
, used_nodes
))
5002 /* Simple min distance search */
5003 val
= node_distance(node
, n
);
5005 if (val
< min_val
) {
5011 set_bit(best_node
, used_nodes
);
5016 * sched_domain_node_span - get a cpumask for a node's sched_domain
5017 * @node: node whose cpumask we're constructing
5018 * @size: number of nodes to include in this span
5020 * Given a node, construct a good cpumask for its sched_domain to span. It
5021 * should be one that prevents unnecessary balancing, but also spreads tasks
5024 static cpumask_t
sched_domain_node_span(int node
)
5027 cpumask_t span
, nodemask
;
5028 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5031 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5033 nodemask
= node_to_cpumask(node
);
5034 cpus_or(span
, span
, nodemask
);
5035 set_bit(node
, used_nodes
);
5037 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5038 int next_node
= find_next_best_node(node
, used_nodes
);
5039 nodemask
= node_to_cpumask(next_node
);
5040 cpus_or(span
, span
, nodemask
);
5048 * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
5049 * can switch it on easily if needed.
5051 #ifdef CONFIG_SCHED_SMT
5052 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5053 static struct sched_group sched_group_cpus
[NR_CPUS
];
5054 static int cpu_to_cpu_group(int cpu
)
5060 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5061 static struct sched_group sched_group_phys
[NR_CPUS
];
5062 static int cpu_to_phys_group(int cpu
)
5064 #ifdef CONFIG_SCHED_SMT
5065 return first_cpu(cpu_sibling_map
[cpu
]);
5073 * The init_sched_build_groups can't handle what we want to do with node
5074 * groups, so roll our own. Now each node has its own list of groups which
5075 * gets dynamically allocated.
5077 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5078 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5080 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5081 static struct sched_group
*sched_group_allnodes_bycpu
[NR_CPUS
];
5083 static int cpu_to_allnodes_group(int cpu
)
5085 return cpu_to_node(cpu
);
5090 * Build sched domains for a given set of cpus and attach the sched domains
5091 * to the individual cpus
5093 void build_sched_domains(const cpumask_t
*cpu_map
)
5097 struct sched_group
**sched_group_nodes
= NULL
;
5098 struct sched_group
*sched_group_allnodes
= NULL
;
5101 * Allocate the per-node list of sched groups
5103 sched_group_nodes
= kmalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
5105 if (!sched_group_nodes
) {
5106 printk(KERN_WARNING
"Can not alloc sched group node list\n");
5109 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
5113 * Set up domains for cpus specified by the cpu_map.
5115 for_each_cpu_mask(i
, *cpu_map
) {
5117 struct sched_domain
*sd
= NULL
, *p
;
5118 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
5120 cpus_and(nodemask
, nodemask
, *cpu_map
);
5123 if (cpus_weight(*cpu_map
)
5124 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
5125 if (!sched_group_allnodes
) {
5126 sched_group_allnodes
5127 = kmalloc(sizeof(struct sched_group
)
5130 if (!sched_group_allnodes
) {
5132 "Can not alloc allnodes sched group\n");
5135 sched_group_allnodes_bycpu
[i
]
5136 = sched_group_allnodes
;
5138 sd
= &per_cpu(allnodes_domains
, i
);
5139 *sd
= SD_ALLNODES_INIT
;
5140 sd
->span
= *cpu_map
;
5141 group
= cpu_to_allnodes_group(i
);
5142 sd
->groups
= &sched_group_allnodes
[group
];
5147 sd
= &per_cpu(node_domains
, i
);
5149 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
5151 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5155 sd
= &per_cpu(phys_domains
, i
);
5156 group
= cpu_to_phys_group(i
);
5158 sd
->span
= nodemask
;
5160 sd
->groups
= &sched_group_phys
[group
];
5162 #ifdef CONFIG_SCHED_SMT
5164 sd
= &per_cpu(cpu_domains
, i
);
5165 group
= cpu_to_cpu_group(i
);
5166 *sd
= SD_SIBLING_INIT
;
5167 sd
->span
= cpu_sibling_map
[i
];
5168 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5170 sd
->groups
= &sched_group_cpus
[group
];
5174 #ifdef CONFIG_SCHED_SMT
5175 /* Set up CPU (sibling) groups */
5176 for_each_cpu_mask(i
, *cpu_map
) {
5177 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
5178 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
5179 if (i
!= first_cpu(this_sibling_map
))
5182 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
5187 /* Set up physical groups */
5188 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5189 cpumask_t nodemask
= node_to_cpumask(i
);
5191 cpus_and(nodemask
, nodemask
, *cpu_map
);
5192 if (cpus_empty(nodemask
))
5195 init_sched_build_groups(sched_group_phys
, nodemask
,
5196 &cpu_to_phys_group
);
5200 /* Set up node groups */
5201 if (sched_group_allnodes
)
5202 init_sched_build_groups(sched_group_allnodes
, *cpu_map
,
5203 &cpu_to_allnodes_group
);
5205 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5206 /* Set up node groups */
5207 struct sched_group
*sg
, *prev
;
5208 cpumask_t nodemask
= node_to_cpumask(i
);
5209 cpumask_t domainspan
;
5210 cpumask_t covered
= CPU_MASK_NONE
;
5213 cpus_and(nodemask
, nodemask
, *cpu_map
);
5214 if (cpus_empty(nodemask
)) {
5215 sched_group_nodes
[i
] = NULL
;
5219 domainspan
= sched_domain_node_span(i
);
5220 cpus_and(domainspan
, domainspan
, *cpu_map
);
5222 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5223 sched_group_nodes
[i
] = sg
;
5224 for_each_cpu_mask(j
, nodemask
) {
5225 struct sched_domain
*sd
;
5226 sd
= &per_cpu(node_domains
, j
);
5228 if (sd
->groups
== NULL
) {
5229 /* Turn off balancing if we have no groups */
5235 "Can not alloc domain group for node %d\n", i
);
5239 sg
->cpumask
= nodemask
;
5240 cpus_or(covered
, covered
, nodemask
);
5243 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
5244 cpumask_t tmp
, notcovered
;
5245 int n
= (i
+ j
) % MAX_NUMNODES
;
5247 cpus_complement(notcovered
, covered
);
5248 cpus_and(tmp
, notcovered
, *cpu_map
);
5249 cpus_and(tmp
, tmp
, domainspan
);
5250 if (cpus_empty(tmp
))
5253 nodemask
= node_to_cpumask(n
);
5254 cpus_and(tmp
, tmp
, nodemask
);
5255 if (cpus_empty(tmp
))
5258 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5261 "Can not alloc domain group for node %d\n", j
);
5266 cpus_or(covered
, covered
, tmp
);
5270 prev
->next
= sched_group_nodes
[i
];
5274 /* Calculate CPU power for physical packages and nodes */
5275 for_each_cpu_mask(i
, *cpu_map
) {
5277 struct sched_domain
*sd
;
5278 #ifdef CONFIG_SCHED_SMT
5279 sd
= &per_cpu(cpu_domains
, i
);
5280 power
= SCHED_LOAD_SCALE
;
5281 sd
->groups
->cpu_power
= power
;
5284 sd
= &per_cpu(phys_domains
, i
);
5285 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5286 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5287 sd
->groups
->cpu_power
= power
;
5290 sd
= &per_cpu(allnodes_domains
, i
);
5292 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5293 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5294 sd
->groups
->cpu_power
= power
;
5300 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5301 struct sched_group
*sg
= sched_group_nodes
[i
];
5307 for_each_cpu_mask(j
, sg
->cpumask
) {
5308 struct sched_domain
*sd
;
5311 sd
= &per_cpu(phys_domains
, j
);
5312 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5314 * Only add "power" once for each
5319 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5320 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5322 sg
->cpu_power
+= power
;
5325 if (sg
!= sched_group_nodes
[i
])
5330 /* Attach the domains */
5331 for_each_cpu_mask(i
, *cpu_map
) {
5332 struct sched_domain
*sd
;
5333 #ifdef CONFIG_SCHED_SMT
5334 sd
= &per_cpu(cpu_domains
, i
);
5336 sd
= &per_cpu(phys_domains
, i
);
5338 cpu_attach_domain(sd
, i
);
5342 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5344 static void arch_init_sched_domains(const cpumask_t
*cpu_map
)
5346 cpumask_t cpu_default_map
;
5349 * Setup mask for cpus without special case scheduling requirements.
5350 * For now this just excludes isolated cpus, but could be used to
5351 * exclude other special cases in the future.
5353 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
5355 build_sched_domains(&cpu_default_map
);
5358 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
5364 for_each_cpu_mask(cpu
, *cpu_map
) {
5365 struct sched_group
*sched_group_allnodes
5366 = sched_group_allnodes_bycpu
[cpu
];
5367 struct sched_group
**sched_group_nodes
5368 = sched_group_nodes_bycpu
[cpu
];
5370 if (sched_group_allnodes
) {
5371 kfree(sched_group_allnodes
);
5372 sched_group_allnodes_bycpu
[cpu
] = NULL
;
5375 if (!sched_group_nodes
)
5378 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5379 cpumask_t nodemask
= node_to_cpumask(i
);
5380 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5382 cpus_and(nodemask
, nodemask
, *cpu_map
);
5383 if (cpus_empty(nodemask
))
5393 if (oldsg
!= sched_group_nodes
[i
])
5396 kfree(sched_group_nodes
);
5397 sched_group_nodes_bycpu
[cpu
] = NULL
;
5403 * Detach sched domains from a group of cpus specified in cpu_map
5404 * These cpus will now be attached to the NULL domain
5406 static inline void detach_destroy_domains(const cpumask_t
*cpu_map
)
5410 for_each_cpu_mask(i
, *cpu_map
)
5411 cpu_attach_domain(NULL
, i
);
5412 synchronize_sched();
5413 arch_destroy_sched_domains(cpu_map
);
5417 * Partition sched domains as specified by the cpumasks below.
5418 * This attaches all cpus from the cpumasks to the NULL domain,
5419 * waits for a RCU quiescent period, recalculates sched
5420 * domain information and then attaches them back to the
5421 * correct sched domains
5422 * Call with hotplug lock held
5424 void partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
5426 cpumask_t change_map
;
5428 cpus_and(*partition1
, *partition1
, cpu_online_map
);
5429 cpus_and(*partition2
, *partition2
, cpu_online_map
);
5430 cpus_or(change_map
, *partition1
, *partition2
);
5432 /* Detach sched domains from all of the affected cpus */
5433 detach_destroy_domains(&change_map
);
5434 if (!cpus_empty(*partition1
))
5435 build_sched_domains(partition1
);
5436 if (!cpus_empty(*partition2
))
5437 build_sched_domains(partition2
);
5440 #ifdef CONFIG_HOTPLUG_CPU
5442 * Force a reinitialization of the sched domains hierarchy. The domains
5443 * and groups cannot be updated in place without racing with the balancing
5444 * code, so we temporarily attach all running cpus to the NULL domain
5445 * which will prevent rebalancing while the sched domains are recalculated.
5447 static int update_sched_domains(struct notifier_block
*nfb
,
5448 unsigned long action
, void *hcpu
)
5451 case CPU_UP_PREPARE
:
5452 case CPU_DOWN_PREPARE
:
5453 detach_destroy_domains(&cpu_online_map
);
5456 case CPU_UP_CANCELED
:
5457 case CPU_DOWN_FAILED
:
5461 * Fall through and re-initialise the domains.
5468 /* The hotplug lock is already held by cpu_up/cpu_down */
5469 arch_init_sched_domains(&cpu_online_map
);
5475 void __init
sched_init_smp(void)
5478 arch_init_sched_domains(&cpu_online_map
);
5479 unlock_cpu_hotplug();
5480 /* XXX: Theoretical race here - CPU may be hotplugged now */
5481 hotcpu_notifier(update_sched_domains
, 0);
5484 void __init
sched_init_smp(void)
5487 #endif /* CONFIG_SMP */
5489 int in_sched_functions(unsigned long addr
)
5491 /* Linker adds these: start and end of __sched functions */
5492 extern char __sched_text_start
[], __sched_text_end
[];
5493 return in_lock_functions(addr
) ||
5494 (addr
>= (unsigned long)__sched_text_start
5495 && addr
< (unsigned long)__sched_text_end
);
5498 void __init
sched_init(void)
5503 for (i
= 0; i
< NR_CPUS
; i
++) {
5504 prio_array_t
*array
;
5507 spin_lock_init(&rq
->lock
);
5509 rq
->active
= rq
->arrays
;
5510 rq
->expired
= rq
->arrays
+ 1;
5511 rq
->best_expired_prio
= MAX_PRIO
;
5515 for (j
= 1; j
< 3; j
++)
5516 rq
->cpu_load
[j
] = 0;
5517 rq
->active_balance
= 0;
5519 rq
->migration_thread
= NULL
;
5520 INIT_LIST_HEAD(&rq
->migration_queue
);
5522 atomic_set(&rq
->nr_iowait
, 0);
5524 for (j
= 0; j
< 2; j
++) {
5525 array
= rq
->arrays
+ j
;
5526 for (k
= 0; k
< MAX_PRIO
; k
++) {
5527 INIT_LIST_HEAD(array
->queue
+ k
);
5528 __clear_bit(k
, array
->bitmap
);
5530 // delimiter for bitsearch
5531 __set_bit(MAX_PRIO
, array
->bitmap
);
5536 * The boot idle thread does lazy MMU switching as well:
5538 atomic_inc(&init_mm
.mm_count
);
5539 enter_lazy_tlb(&init_mm
, current
);
5542 * Make us the idle thread. Technically, schedule() should not be
5543 * called from this thread, however somewhere below it might be,
5544 * but because we are the idle thread, we just pick up running again
5545 * when this runqueue becomes "idle".
5547 init_idle(current
, smp_processor_id());
5550 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5551 void __might_sleep(char *file
, int line
)
5553 #if defined(in_atomic)
5554 static unsigned long prev_jiffy
; /* ratelimiting */
5556 if ((in_atomic() || irqs_disabled()) &&
5557 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
5558 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
5560 prev_jiffy
= jiffies
;
5561 printk(KERN_ERR
"Debug: sleeping function called from invalid"
5562 " context at %s:%d\n", file
, line
);
5563 printk("in_atomic():%d, irqs_disabled():%d\n",
5564 in_atomic(), irqs_disabled());
5569 EXPORT_SYMBOL(__might_sleep
);
5572 #ifdef CONFIG_MAGIC_SYSRQ
5573 void normalize_rt_tasks(void)
5575 struct task_struct
*p
;
5576 prio_array_t
*array
;
5577 unsigned long flags
;
5580 read_lock_irq(&tasklist_lock
);
5581 for_each_process (p
) {
5585 rq
= task_rq_lock(p
, &flags
);
5589 deactivate_task(p
, task_rq(p
));
5590 __setscheduler(p
, SCHED_NORMAL
, 0);
5592 __activate_task(p
, task_rq(p
));
5593 resched_task(rq
->curr
);
5596 task_rq_unlock(rq
, &flags
);
5598 read_unlock_irq(&tasklist_lock
);
5601 #endif /* CONFIG_MAGIC_SYSRQ */
5605 * These functions are only useful for the IA64 MCA handling.
5607 * They can only be called when the whole system has been
5608 * stopped - every CPU needs to be quiescent, and no scheduling
5609 * activity can take place. Using them for anything else would
5610 * be a serious bug, and as a result, they aren't even visible
5611 * under any other configuration.
5615 * curr_task - return the current task for a given cpu.
5616 * @cpu: the processor in question.
5618 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
5620 task_t
*curr_task(int cpu
)
5622 return cpu_curr(cpu
);
5626 * set_curr_task - set the current task for a given cpu.
5627 * @cpu: the processor in question.
5628 * @p: the task pointer to set.
5630 * Description: This function must only be used when non-maskable interrupts
5631 * are serviced on a separate stack. It allows the architecture to switch the
5632 * notion of the current task on a cpu in a non-blocking manner. This function
5633 * must be called with all CPU's synchronized, and interrupts disabled, the
5634 * and caller must save the original value of the current task (see
5635 * curr_task() above) and restore that value before reenabling interrupts and
5636 * re-starting the system.
5638 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
5640 void set_curr_task(int cpu
, task_t
*p
)