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/capability.h>
31 #include <linux/completion.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/security.h>
34 #include <linux/notifier.h>
35 #include <linux/profile.h>
36 #include <linux/suspend.h>
37 #include <linux/blkdev.h>
38 #include <linux/delay.h>
39 #include <linux/smp.h>
40 #include <linux/threads.h>
41 #include <linux/timer.h>
42 #include <linux/rcupdate.h>
43 #include <linux/cpu.h>
44 #include <linux/cpuset.h>
45 #include <linux/percpu.h>
46 #include <linux/kthread.h>
47 #include <linux/seq_file.h>
48 #include <linux/syscalls.h>
49 #include <linux/times.h>
50 #include <linux/acct.h>
53 #include <asm/unistd.h>
56 * Convert user-nice values [ -20 ... 0 ... 19 ]
57 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
60 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
61 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
62 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
65 * 'User priority' is the nice value converted to something we
66 * can work with better when scaling various scheduler parameters,
67 * it's a [ 0 ... 39 ] range.
69 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
70 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
71 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
74 * Some helpers for converting nanosecond timing to jiffy resolution
76 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
77 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
80 * These are the 'tuning knobs' of the scheduler:
82 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
83 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
84 * Timeslices get refilled after they expire.
86 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
87 #define DEF_TIMESLICE (100 * HZ / 1000)
88 #define ON_RUNQUEUE_WEIGHT 30
89 #define CHILD_PENALTY 95
90 #define PARENT_PENALTY 100
92 #define PRIO_BONUS_RATIO 25
93 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
94 #define INTERACTIVE_DELTA 2
95 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
96 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
97 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
100 * If a task is 'interactive' then we reinsert it in the active
101 * array after it has expired its current timeslice. (it will not
102 * continue to run immediately, it will still roundrobin with
103 * other interactive tasks.)
105 * This part scales the interactivity limit depending on niceness.
107 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
108 * Here are a few examples of different nice levels:
110 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
111 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
112 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
113 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
114 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
116 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
117 * priority range a task can explore, a value of '1' means the
118 * task is rated interactive.)
120 * Ie. nice +19 tasks can never get 'interactive' enough to be
121 * reinserted into the active array. And only heavily CPU-hog nice -20
122 * tasks will be expired. Default nice 0 tasks are somewhere between,
123 * it takes some effort for them to get interactive, but it's not
127 #define CURRENT_BONUS(p) \
128 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
131 #define GRANULARITY (10 * HZ / 1000 ? : 1)
134 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
135 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
138 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
139 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
142 #define SCALE(v1,v1_max,v2_max) \
143 (v1) * (v2_max) / (v1_max)
146 (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
148 #define TASK_INTERACTIVE(p) \
149 ((p)->prio <= (p)->static_prio - DELTA(p))
151 #define INTERACTIVE_SLEEP(p) \
152 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
153 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
155 #define TASK_PREEMPTS_CURR(p, rq) \
156 ((p)->prio < (rq)->curr->prio)
159 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
160 * to time slice values: [800ms ... 100ms ... 5ms]
162 * The higher a thread's priority, the bigger timeslices
163 * it gets during one round of execution. But even the lowest
164 * priority thread gets MIN_TIMESLICE worth of execution time.
167 #define SCALE_PRIO(x, prio) \
168 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
170 static unsigned int task_timeslice(task_t
*p
)
172 if (p
->static_prio
< NICE_TO_PRIO(0))
173 return SCALE_PRIO(DEF_TIMESLICE
*4, p
->static_prio
);
175 return SCALE_PRIO(DEF_TIMESLICE
, p
->static_prio
);
177 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
178 < (long long) (sd)->cache_hot_time)
180 void __put_task_struct_cb(struct rcu_head
*rhp
)
182 __put_task_struct(container_of(rhp
, struct task_struct
, rcu
));
185 EXPORT_SYMBOL_GPL(__put_task_struct_cb
);
188 * These are the runqueue data structures:
191 #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
193 typedef struct runqueue runqueue_t
;
196 unsigned int nr_active
;
197 unsigned long bitmap
[BITMAP_SIZE
];
198 struct list_head queue
[MAX_PRIO
];
202 * This is the main, per-CPU runqueue data structure.
204 * Locking rule: those places that want to lock multiple runqueues
205 * (such as the load balancing or the thread migration code), lock
206 * acquire operations must be ordered by ascending &runqueue.
212 * nr_running and cpu_load should be in the same cacheline because
213 * remote CPUs use both these fields when doing load calculation.
215 unsigned long nr_running
;
217 unsigned long prio_bias
;
218 unsigned long cpu_load
[3];
220 unsigned long long nr_switches
;
223 * This is part of a global counter where only the total sum
224 * over all CPUs matters. A task can increase this counter on
225 * one CPU and if it got migrated afterwards it may decrease
226 * it on another CPU. Always updated under the runqueue lock:
228 unsigned long nr_uninterruptible
;
230 unsigned long expired_timestamp
;
231 unsigned long long timestamp_last_tick
;
233 struct mm_struct
*prev_mm
;
234 prio_array_t
*active
, *expired
, arrays
[2];
235 int best_expired_prio
;
239 struct sched_domain
*sd
;
241 /* For active balancing */
245 task_t
*migration_thread
;
246 struct list_head migration_queue
;
249 #ifdef CONFIG_SCHEDSTATS
251 struct sched_info rq_sched_info
;
253 /* sys_sched_yield() stats */
254 unsigned long yld_exp_empty
;
255 unsigned long yld_act_empty
;
256 unsigned long yld_both_empty
;
257 unsigned long yld_cnt
;
259 /* schedule() stats */
260 unsigned long sched_switch
;
261 unsigned long sched_cnt
;
262 unsigned long sched_goidle
;
264 /* try_to_wake_up() stats */
265 unsigned long ttwu_cnt
;
266 unsigned long ttwu_local
;
270 static DEFINE_PER_CPU(struct runqueue
, runqueues
);
273 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
274 * See detach_destroy_domains: synchronize_sched for details.
276 * The domain tree of any CPU may only be accessed from within
277 * preempt-disabled sections.
279 #define for_each_domain(cpu, domain) \
280 for (domain = rcu_dereference(cpu_rq(cpu)->sd); domain; domain = domain->parent)
282 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
283 #define this_rq() (&__get_cpu_var(runqueues))
284 #define task_rq(p) cpu_rq(task_cpu(p))
285 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
287 #ifndef prepare_arch_switch
288 # define prepare_arch_switch(next) do { } while (0)
290 #ifndef finish_arch_switch
291 # define finish_arch_switch(prev) do { } while (0)
294 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
295 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
297 return rq
->curr
== p
;
300 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
304 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
306 #ifdef CONFIG_DEBUG_SPINLOCK
307 /* this is a valid case when another task releases the spinlock */
308 rq
->lock
.owner
= current
;
310 spin_unlock_irq(&rq
->lock
);
313 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
314 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
319 return rq
->curr
== p
;
323 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
327 * We can optimise this out completely for !SMP, because the
328 * SMP rebalancing from interrupt is the only thing that cares
333 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
334 spin_unlock_irq(&rq
->lock
);
336 spin_unlock(&rq
->lock
);
340 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
344 * After ->oncpu is cleared, the task can be moved to a different CPU.
345 * We must ensure this doesn't happen until the switch is completely
351 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
355 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
358 * task_rq_lock - lock the runqueue a given task resides on and disable
359 * interrupts. Note the ordering: we can safely lookup the task_rq without
360 * explicitly disabling preemption.
362 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
368 local_irq_save(*flags
);
370 spin_lock(&rq
->lock
);
371 if (unlikely(rq
!= task_rq(p
))) {
372 spin_unlock_irqrestore(&rq
->lock
, *flags
);
373 goto repeat_lock_task
;
378 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
381 spin_unlock_irqrestore(&rq
->lock
, *flags
);
384 #ifdef CONFIG_SCHEDSTATS
386 * bump this up when changing the output format or the meaning of an existing
387 * format, so that tools can adapt (or abort)
389 #define SCHEDSTAT_VERSION 12
391 static int show_schedstat(struct seq_file
*seq
, void *v
)
395 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
396 seq_printf(seq
, "timestamp %lu\n", jiffies
);
397 for_each_online_cpu(cpu
) {
398 runqueue_t
*rq
= cpu_rq(cpu
);
400 struct sched_domain
*sd
;
404 /* runqueue-specific stats */
406 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
407 cpu
, rq
->yld_both_empty
,
408 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
409 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
410 rq
->ttwu_cnt
, rq
->ttwu_local
,
411 rq
->rq_sched_info
.cpu_time
,
412 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
414 seq_printf(seq
, "\n");
417 /* domain-specific stats */
419 for_each_domain(cpu
, sd
) {
420 enum idle_type itype
;
421 char mask_str
[NR_CPUS
];
423 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
424 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
425 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
427 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
429 sd
->lb_balanced
[itype
],
430 sd
->lb_failed
[itype
],
431 sd
->lb_imbalance
[itype
],
432 sd
->lb_gained
[itype
],
433 sd
->lb_hot_gained
[itype
],
434 sd
->lb_nobusyq
[itype
],
435 sd
->lb_nobusyg
[itype
]);
437 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
438 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
439 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
440 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
441 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
449 static int schedstat_open(struct inode
*inode
, struct file
*file
)
451 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
452 char *buf
= kmalloc(size
, GFP_KERNEL
);
458 res
= single_open(file
, show_schedstat
, NULL
);
460 m
= file
->private_data
;
468 struct file_operations proc_schedstat_operations
= {
469 .open
= schedstat_open
,
472 .release
= single_release
,
475 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
476 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
477 #else /* !CONFIG_SCHEDSTATS */
478 # define schedstat_inc(rq, field) do { } while (0)
479 # define schedstat_add(rq, field, amt) do { } while (0)
483 * rq_lock - lock a given runqueue and disable interrupts.
485 static inline runqueue_t
*this_rq_lock(void)
492 spin_lock(&rq
->lock
);
497 #ifdef CONFIG_SCHEDSTATS
499 * Called when a process is dequeued from the active array and given
500 * the cpu. We should note that with the exception of interactive
501 * tasks, the expired queue will become the active queue after the active
502 * queue is empty, without explicitly dequeuing and requeuing tasks in the
503 * expired queue. (Interactive tasks may be requeued directly to the
504 * active queue, thus delaying tasks in the expired queue from running;
505 * see scheduler_tick()).
507 * This function is only called from sched_info_arrive(), rather than
508 * dequeue_task(). Even though a task may be queued and dequeued multiple
509 * times as it is shuffled about, we're really interested in knowing how
510 * long it was from the *first* time it was queued to the time that it
513 static inline void sched_info_dequeued(task_t
*t
)
515 t
->sched_info
.last_queued
= 0;
519 * Called when a task finally hits the cpu. We can now calculate how
520 * long it was waiting to run. We also note when it began so that we
521 * can keep stats on how long its timeslice is.
523 static inline void sched_info_arrive(task_t
*t
)
525 unsigned long now
= jiffies
, diff
= 0;
526 struct runqueue
*rq
= task_rq(t
);
528 if (t
->sched_info
.last_queued
)
529 diff
= now
- t
->sched_info
.last_queued
;
530 sched_info_dequeued(t
);
531 t
->sched_info
.run_delay
+= diff
;
532 t
->sched_info
.last_arrival
= now
;
533 t
->sched_info
.pcnt
++;
538 rq
->rq_sched_info
.run_delay
+= diff
;
539 rq
->rq_sched_info
.pcnt
++;
543 * Called when a process is queued into either the active or expired
544 * array. The time is noted and later used to determine how long we
545 * had to wait for us to reach the cpu. Since the expired queue will
546 * become the active queue after active queue is empty, without dequeuing
547 * and requeuing any tasks, we are interested in queuing to either. It
548 * is unusual but not impossible for tasks to be dequeued and immediately
549 * requeued in the same or another array: this can happen in sched_yield(),
550 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
553 * This function is only called from enqueue_task(), but also only updates
554 * the timestamp if it is already not set. It's assumed that
555 * sched_info_dequeued() will clear that stamp when appropriate.
557 static inline void sched_info_queued(task_t
*t
)
559 if (!t
->sched_info
.last_queued
)
560 t
->sched_info
.last_queued
= jiffies
;
564 * Called when a process ceases being the active-running process, either
565 * voluntarily or involuntarily. Now we can calculate how long we ran.
567 static inline void sched_info_depart(task_t
*t
)
569 struct runqueue
*rq
= task_rq(t
);
570 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
572 t
->sched_info
.cpu_time
+= diff
;
575 rq
->rq_sched_info
.cpu_time
+= diff
;
579 * Called when tasks are switched involuntarily due, typically, to expiring
580 * their time slice. (This may also be called when switching to or from
581 * the idle task.) We are only called when prev != next.
583 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
585 struct runqueue
*rq
= task_rq(prev
);
588 * prev now departs the cpu. It's not interesting to record
589 * stats about how efficient we were at scheduling the idle
592 if (prev
!= rq
->idle
)
593 sched_info_depart(prev
);
595 if (next
!= rq
->idle
)
596 sched_info_arrive(next
);
599 #define sched_info_queued(t) do { } while (0)
600 #define sched_info_switch(t, next) do { } while (0)
601 #endif /* CONFIG_SCHEDSTATS */
604 * Adding/removing a task to/from a priority array:
606 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
609 list_del(&p
->run_list
);
610 if (list_empty(array
->queue
+ p
->prio
))
611 __clear_bit(p
->prio
, array
->bitmap
);
614 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
616 sched_info_queued(p
);
617 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
618 __set_bit(p
->prio
, array
->bitmap
);
624 * Put task to the end of the run list without the overhead of dequeue
625 * followed by enqueue.
627 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
629 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
632 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
634 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
635 __set_bit(p
->prio
, array
->bitmap
);
641 * effective_prio - return the priority that is based on the static
642 * priority but is modified by bonuses/penalties.
644 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
645 * into the -5 ... 0 ... +5 bonus/penalty range.
647 * We use 25% of the full 0...39 priority range so that:
649 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
650 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
652 * Both properties are important to certain workloads.
654 static int effective_prio(task_t
*p
)
661 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
663 prio
= p
->static_prio
- bonus
;
664 if (prio
< MAX_RT_PRIO
)
666 if (prio
> MAX_PRIO
-1)
672 static inline void inc_prio_bias(runqueue_t
*rq
, int prio
)
674 rq
->prio_bias
+= MAX_PRIO
- prio
;
677 static inline void dec_prio_bias(runqueue_t
*rq
, int prio
)
679 rq
->prio_bias
-= MAX_PRIO
- prio
;
682 static inline void inc_nr_running(task_t
*p
, runqueue_t
*rq
)
686 if (p
!= rq
->migration_thread
)
688 * The migration thread does the actual balancing. Do
689 * not bias by its priority as the ultra high priority
690 * will skew balancing adversely.
692 inc_prio_bias(rq
, p
->prio
);
694 inc_prio_bias(rq
, p
->static_prio
);
697 static inline void dec_nr_running(task_t
*p
, runqueue_t
*rq
)
701 if (p
!= rq
->migration_thread
)
702 dec_prio_bias(rq
, p
->prio
);
704 dec_prio_bias(rq
, p
->static_prio
);
707 static inline void inc_prio_bias(runqueue_t
*rq
, int prio
)
711 static inline void dec_prio_bias(runqueue_t
*rq
, int prio
)
715 static inline void inc_nr_running(task_t
*p
, runqueue_t
*rq
)
720 static inline void dec_nr_running(task_t
*p
, runqueue_t
*rq
)
727 * __activate_task - move a task to the runqueue.
729 static inline void __activate_task(task_t
*p
, runqueue_t
*rq
)
731 enqueue_task(p
, rq
->active
);
732 inc_nr_running(p
, rq
);
736 * __activate_idle_task - move idle task to the _front_ of runqueue.
738 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
740 enqueue_task_head(p
, rq
->active
);
741 inc_nr_running(p
, rq
);
744 static int recalc_task_prio(task_t
*p
, unsigned long long now
)
746 /* Caller must always ensure 'now >= p->timestamp' */
747 unsigned long long __sleep_time
= now
- p
->timestamp
;
748 unsigned long sleep_time
;
750 if (__sleep_time
> NS_MAX_SLEEP_AVG
)
751 sleep_time
= NS_MAX_SLEEP_AVG
;
753 sleep_time
= (unsigned long)__sleep_time
;
755 if (likely(sleep_time
> 0)) {
757 * User tasks that sleep a long time are categorised as
758 * idle and will get just interactive status to stay active &
759 * prevent them suddenly becoming cpu hogs and starving
762 if (p
->mm
&& p
->activated
!= -1 &&
763 sleep_time
> INTERACTIVE_SLEEP(p
)) {
764 p
->sleep_avg
= JIFFIES_TO_NS(MAX_SLEEP_AVG
-
768 * The lower the sleep avg a task has the more
769 * rapidly it will rise with sleep time.
771 sleep_time
*= (MAX_BONUS
- CURRENT_BONUS(p
)) ? : 1;
774 * Tasks waking from uninterruptible sleep are
775 * limited in their sleep_avg rise as they
776 * are likely to be waiting on I/O
778 if (p
->activated
== -1 && p
->mm
) {
779 if (p
->sleep_avg
>= INTERACTIVE_SLEEP(p
))
781 else if (p
->sleep_avg
+ sleep_time
>=
782 INTERACTIVE_SLEEP(p
)) {
783 p
->sleep_avg
= INTERACTIVE_SLEEP(p
);
789 * This code gives a bonus to interactive tasks.
791 * The boost works by updating the 'average sleep time'
792 * value here, based on ->timestamp. The more time a
793 * task spends sleeping, the higher the average gets -
794 * and the higher the priority boost gets as well.
796 p
->sleep_avg
+= sleep_time
;
798 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
799 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
803 return effective_prio(p
);
807 * activate_task - move a task to the runqueue and do priority recalculation
809 * Update all the scheduling statistics stuff. (sleep average
810 * calculation, priority modifiers, etc.)
812 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
814 unsigned long long now
;
819 /* Compensate for drifting sched_clock */
820 runqueue_t
*this_rq
= this_rq();
821 now
= (now
- this_rq
->timestamp_last_tick
)
822 + rq
->timestamp_last_tick
;
827 p
->prio
= recalc_task_prio(p
, now
);
830 * This checks to make sure it's not an uninterruptible task
831 * that is now waking up.
835 * Tasks which were woken up by interrupts (ie. hw events)
836 * are most likely of interactive nature. So we give them
837 * the credit of extending their sleep time to the period
838 * of time they spend on the runqueue, waiting for execution
839 * on a CPU, first time around:
845 * Normal first-time wakeups get a credit too for
846 * on-runqueue time, but it will be weighted down:
853 __activate_task(p
, rq
);
857 * deactivate_task - remove a task from the runqueue.
859 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
861 dec_nr_running(p
, rq
);
862 dequeue_task(p
, p
->array
);
867 * resched_task - mark a task 'to be rescheduled now'.
869 * On UP this means the setting of the need_resched flag, on SMP it
870 * might also involve a cross-CPU call to trigger the scheduler on
874 static void resched_task(task_t
*p
)
878 assert_spin_locked(&task_rq(p
)->lock
);
880 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
883 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
886 if (cpu
== smp_processor_id())
889 /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */
891 if (!test_tsk_thread_flag(p
, TIF_POLLING_NRFLAG
))
892 smp_send_reschedule(cpu
);
895 static inline void resched_task(task_t
*p
)
897 assert_spin_locked(&task_rq(p
)->lock
);
898 set_tsk_need_resched(p
);
903 * task_curr - is this task currently executing on a CPU?
904 * @p: the task in question.
906 inline int task_curr(const task_t
*p
)
908 return cpu_curr(task_cpu(p
)) == p
;
913 struct list_head list
;
918 struct completion done
;
922 * The task's runqueue lock must be held.
923 * Returns true if you have to wait for migration thread.
925 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
927 runqueue_t
*rq
= task_rq(p
);
930 * If the task is not on a runqueue (and not running), then
931 * it is sufficient to simply update the task's cpu field.
933 if (!p
->array
&& !task_running(rq
, p
)) {
934 set_task_cpu(p
, dest_cpu
);
938 init_completion(&req
->done
);
940 req
->dest_cpu
= dest_cpu
;
941 list_add(&req
->list
, &rq
->migration_queue
);
946 * wait_task_inactive - wait for a thread to unschedule.
948 * The caller must ensure that the task *will* unschedule sometime soon,
949 * else this function might spin for a *long* time. This function can't
950 * be called with interrupts off, or it may introduce deadlock with
951 * smp_call_function() if an IPI is sent by the same process we are
952 * waiting to become inactive.
954 void wait_task_inactive(task_t
*p
)
961 rq
= task_rq_lock(p
, &flags
);
962 /* Must be off runqueue entirely, not preempted. */
963 if (unlikely(p
->array
|| task_running(rq
, p
))) {
964 /* If it's preempted, we yield. It could be a while. */
965 preempted
= !task_running(rq
, p
);
966 task_rq_unlock(rq
, &flags
);
972 task_rq_unlock(rq
, &flags
);
976 * kick_process - kick a running thread to enter/exit the kernel
977 * @p: the to-be-kicked thread
979 * Cause a process which is running on another CPU to enter
980 * kernel-mode, without any delay. (to get signals handled.)
982 * NOTE: this function doesnt have to take the runqueue lock,
983 * because all it wants to ensure is that the remote task enters
984 * the kernel. If the IPI races and the task has been migrated
985 * to another CPU then no harm is done and the purpose has been
988 void kick_process(task_t
*p
)
994 if ((cpu
!= smp_processor_id()) && task_curr(p
))
995 smp_send_reschedule(cpu
);
1000 * Return a low guess at the load of a migration-source cpu.
1002 * We want to under-estimate the load of migration sources, to
1003 * balance conservatively.
1005 static inline unsigned long __source_load(int cpu
, int type
, enum idle_type idle
)
1007 runqueue_t
*rq
= cpu_rq(cpu
);
1008 unsigned long running
= rq
->nr_running
;
1009 unsigned long source_load
, cpu_load
= rq
->cpu_load
[type
-1],
1010 load_now
= running
* SCHED_LOAD_SCALE
;
1013 source_load
= load_now
;
1015 source_load
= min(cpu_load
, load_now
);
1017 if (running
> 1 || (idle
== NOT_IDLE
&& running
))
1019 * If we are busy rebalancing the load is biased by
1020 * priority to create 'nice' support across cpus. When
1021 * idle rebalancing we should only bias the source_load if
1022 * there is more than one task running on that queue to
1023 * prevent idle rebalance from trying to pull tasks from a
1024 * queue with only one running task.
1026 source_load
= source_load
* rq
->prio_bias
/ running
;
1031 static inline unsigned long source_load(int cpu
, int type
)
1033 return __source_load(cpu
, type
, NOT_IDLE
);
1037 * Return a high guess at the load of a migration-target cpu
1039 static inline unsigned long __target_load(int cpu
, int type
, enum idle_type idle
)
1041 runqueue_t
*rq
= cpu_rq(cpu
);
1042 unsigned long running
= rq
->nr_running
;
1043 unsigned long target_load
, cpu_load
= rq
->cpu_load
[type
-1],
1044 load_now
= running
* SCHED_LOAD_SCALE
;
1047 target_load
= load_now
;
1049 target_load
= max(cpu_load
, load_now
);
1051 if (running
> 1 || (idle
== NOT_IDLE
&& running
))
1052 target_load
= target_load
* rq
->prio_bias
/ running
;
1057 static inline unsigned long target_load(int cpu
, int type
)
1059 return __target_load(cpu
, type
, NOT_IDLE
);
1063 * find_idlest_group finds and returns the least busy CPU group within the
1066 static struct sched_group
*
1067 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1069 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1070 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1071 int load_idx
= sd
->forkexec_idx
;
1072 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1075 unsigned long load
, avg_load
;
1079 /* Skip over this group if it has no CPUs allowed */
1080 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1083 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1085 /* Tally up the load of all CPUs in the group */
1088 for_each_cpu_mask(i
, group
->cpumask
) {
1089 /* Bias balancing toward cpus of our domain */
1091 load
= source_load(i
, load_idx
);
1093 load
= target_load(i
, load_idx
);
1098 /* Adjust by relative CPU power of the group */
1099 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1102 this_load
= avg_load
;
1104 } else if (avg_load
< min_load
) {
1105 min_load
= avg_load
;
1109 group
= group
->next
;
1110 } while (group
!= sd
->groups
);
1112 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1118 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1121 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1124 unsigned long load
, min_load
= ULONG_MAX
;
1128 /* Traverse only the allowed CPUs */
1129 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1131 for_each_cpu_mask(i
, tmp
) {
1132 load
= source_load(i
, 0);
1134 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1144 * sched_balance_self: balance the current task (running on cpu) in domains
1145 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1148 * Balance, ie. select the least loaded group.
1150 * Returns the target CPU number, or the same CPU if no balancing is needed.
1152 * preempt must be disabled.
1154 static int sched_balance_self(int cpu
, int flag
)
1156 struct task_struct
*t
= current
;
1157 struct sched_domain
*tmp
, *sd
= NULL
;
1159 for_each_domain(cpu
, tmp
)
1160 if (tmp
->flags
& flag
)
1165 struct sched_group
*group
;
1170 group
= find_idlest_group(sd
, t
, cpu
);
1174 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1175 if (new_cpu
== -1 || new_cpu
== cpu
)
1178 /* Now try balancing at a lower domain level */
1182 weight
= cpus_weight(span
);
1183 for_each_domain(cpu
, tmp
) {
1184 if (weight
<= cpus_weight(tmp
->span
))
1186 if (tmp
->flags
& flag
)
1189 /* while loop will break here if sd == NULL */
1195 #endif /* CONFIG_SMP */
1198 * wake_idle() will wake a task on an idle cpu if task->cpu is
1199 * not idle and an idle cpu is available. The span of cpus to
1200 * search starts with cpus closest then further out as needed,
1201 * so we always favor a closer, idle cpu.
1203 * Returns the CPU we should wake onto.
1205 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1206 static int wake_idle(int cpu
, task_t
*p
)
1209 struct sched_domain
*sd
;
1215 for_each_domain(cpu
, sd
) {
1216 if (sd
->flags
& SD_WAKE_IDLE
) {
1217 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1218 for_each_cpu_mask(i
, tmp
) {
1229 static inline int wake_idle(int cpu
, task_t
*p
)
1236 * try_to_wake_up - wake up a thread
1237 * @p: the to-be-woken-up thread
1238 * @state: the mask of task states that can be woken
1239 * @sync: do a synchronous wakeup?
1241 * Put it on the run-queue if it's not already there. The "current"
1242 * thread is always on the run-queue (except when the actual
1243 * re-schedule is in progress), and as such you're allowed to do
1244 * the simpler "current->state = TASK_RUNNING" to mark yourself
1245 * runnable without the overhead of this.
1247 * returns failure only if the task is already active.
1249 static int try_to_wake_up(task_t
*p
, unsigned int state
, int sync
)
1251 int cpu
, this_cpu
, success
= 0;
1252 unsigned long flags
;
1256 unsigned long load
, this_load
;
1257 struct sched_domain
*sd
, *this_sd
= NULL
;
1261 rq
= task_rq_lock(p
, &flags
);
1262 old_state
= p
->state
;
1263 if (!(old_state
& state
))
1270 this_cpu
= smp_processor_id();
1273 if (unlikely(task_running(rq
, p
)))
1278 schedstat_inc(rq
, ttwu_cnt
);
1279 if (cpu
== this_cpu
) {
1280 schedstat_inc(rq
, ttwu_local
);
1284 for_each_domain(this_cpu
, sd
) {
1285 if (cpu_isset(cpu
, sd
->span
)) {
1286 schedstat_inc(sd
, ttwu_wake_remote
);
1292 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1296 * Check for affine wakeup and passive balancing possibilities.
1299 int idx
= this_sd
->wake_idx
;
1300 unsigned int imbalance
;
1302 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1304 load
= source_load(cpu
, idx
);
1305 this_load
= target_load(this_cpu
, idx
);
1307 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1309 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1310 unsigned long tl
= this_load
;
1312 * If sync wakeup then subtract the (maximum possible)
1313 * effect of the currently running task from the load
1314 * of the current CPU:
1317 tl
-= SCHED_LOAD_SCALE
;
1320 tl
+ target_load(cpu
, idx
) <= SCHED_LOAD_SCALE
) ||
1321 100*(tl
+ SCHED_LOAD_SCALE
) <= imbalance
*load
) {
1323 * This domain has SD_WAKE_AFFINE and
1324 * p is cache cold in this domain, and
1325 * there is no bad imbalance.
1327 schedstat_inc(this_sd
, ttwu_move_affine
);
1333 * Start passive balancing when half the imbalance_pct
1336 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1337 if (imbalance
*this_load
<= 100*load
) {
1338 schedstat_inc(this_sd
, ttwu_move_balance
);
1344 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1346 new_cpu
= wake_idle(new_cpu
, p
);
1347 if (new_cpu
!= cpu
) {
1348 set_task_cpu(p
, new_cpu
);
1349 task_rq_unlock(rq
, &flags
);
1350 /* might preempt at this point */
1351 rq
= task_rq_lock(p
, &flags
);
1352 old_state
= p
->state
;
1353 if (!(old_state
& state
))
1358 this_cpu
= smp_processor_id();
1363 #endif /* CONFIG_SMP */
1364 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1365 rq
->nr_uninterruptible
--;
1367 * Tasks on involuntary sleep don't earn
1368 * sleep_avg beyond just interactive state.
1374 * Tasks that have marked their sleep as noninteractive get
1375 * woken up without updating their sleep average. (i.e. their
1376 * sleep is handled in a priority-neutral manner, no priority
1377 * boost and no penalty.)
1379 if (old_state
& TASK_NONINTERACTIVE
)
1380 __activate_task(p
, rq
);
1382 activate_task(p
, rq
, cpu
== this_cpu
);
1384 * Sync wakeups (i.e. those types of wakeups where the waker
1385 * has indicated that it will leave the CPU in short order)
1386 * don't trigger a preemption, if the woken up task will run on
1387 * this cpu. (in this case the 'I will reschedule' promise of
1388 * the waker guarantees that the freshly woken up task is going
1389 * to be considered on this CPU.)
1391 if (!sync
|| cpu
!= this_cpu
) {
1392 if (TASK_PREEMPTS_CURR(p
, rq
))
1393 resched_task(rq
->curr
);
1398 p
->state
= TASK_RUNNING
;
1400 task_rq_unlock(rq
, &flags
);
1405 int fastcall
wake_up_process(task_t
*p
)
1407 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1408 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1411 EXPORT_SYMBOL(wake_up_process
);
1413 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1415 return try_to_wake_up(p
, state
, 0);
1419 * Perform scheduler related setup for a newly forked process p.
1420 * p is forked by current.
1422 void fastcall
sched_fork(task_t
*p
, int clone_flags
)
1424 int cpu
= get_cpu();
1427 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1429 set_task_cpu(p
, cpu
);
1432 * We mark the process as running here, but have not actually
1433 * inserted it onto the runqueue yet. This guarantees that
1434 * nobody will actually run it, and a signal or other external
1435 * event cannot wake it up and insert it on the runqueue either.
1437 p
->state
= TASK_RUNNING
;
1438 INIT_LIST_HEAD(&p
->run_list
);
1440 #ifdef CONFIG_SCHEDSTATS
1441 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1443 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1446 #ifdef CONFIG_PREEMPT
1447 /* Want to start with kernel preemption disabled. */
1448 task_thread_info(p
)->preempt_count
= 1;
1451 * Share the timeslice between parent and child, thus the
1452 * total amount of pending timeslices in the system doesn't change,
1453 * resulting in more scheduling fairness.
1455 local_irq_disable();
1456 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1458 * The remainder of the first timeslice might be recovered by
1459 * the parent if the child exits early enough.
1461 p
->first_time_slice
= 1;
1462 current
->time_slice
>>= 1;
1463 p
->timestamp
= sched_clock();
1464 if (unlikely(!current
->time_slice
)) {
1466 * This case is rare, it happens when the parent has only
1467 * a single jiffy left from its timeslice. Taking the
1468 * runqueue lock is not a problem.
1470 current
->time_slice
= 1;
1478 * wake_up_new_task - wake up a newly created task for the first time.
1480 * This function will do some initial scheduler statistics housekeeping
1481 * that must be done for every newly created context, then puts the task
1482 * on the runqueue and wakes it.
1484 void fastcall
wake_up_new_task(task_t
*p
, unsigned long clone_flags
)
1486 unsigned long flags
;
1488 runqueue_t
*rq
, *this_rq
;
1490 rq
= task_rq_lock(p
, &flags
);
1491 BUG_ON(p
->state
!= TASK_RUNNING
);
1492 this_cpu
= smp_processor_id();
1496 * We decrease the sleep average of forking parents
1497 * and children as well, to keep max-interactive tasks
1498 * from forking tasks that are max-interactive. The parent
1499 * (current) is done further down, under its lock.
1501 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1502 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1504 p
->prio
= effective_prio(p
);
1506 if (likely(cpu
== this_cpu
)) {
1507 if (!(clone_flags
& CLONE_VM
)) {
1509 * The VM isn't cloned, so we're in a good position to
1510 * do child-runs-first in anticipation of an exec. This
1511 * usually avoids a lot of COW overhead.
1513 if (unlikely(!current
->array
))
1514 __activate_task(p
, rq
);
1516 p
->prio
= current
->prio
;
1517 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1518 p
->array
= current
->array
;
1519 p
->array
->nr_active
++;
1520 inc_nr_running(p
, rq
);
1524 /* Run child last */
1525 __activate_task(p
, rq
);
1527 * We skip the following code due to cpu == this_cpu
1529 * task_rq_unlock(rq, &flags);
1530 * this_rq = task_rq_lock(current, &flags);
1534 this_rq
= cpu_rq(this_cpu
);
1537 * Not the local CPU - must adjust timestamp. This should
1538 * get optimised away in the !CONFIG_SMP case.
1540 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1541 + rq
->timestamp_last_tick
;
1542 __activate_task(p
, rq
);
1543 if (TASK_PREEMPTS_CURR(p
, rq
))
1544 resched_task(rq
->curr
);
1547 * Parent and child are on different CPUs, now get the
1548 * parent runqueue to update the parent's ->sleep_avg:
1550 task_rq_unlock(rq
, &flags
);
1551 this_rq
= task_rq_lock(current
, &flags
);
1553 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1554 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1555 task_rq_unlock(this_rq
, &flags
);
1559 * Potentially available exiting-child timeslices are
1560 * retrieved here - this way the parent does not get
1561 * penalized for creating too many threads.
1563 * (this cannot be used to 'generate' timeslices
1564 * artificially, because any timeslice recovered here
1565 * was given away by the parent in the first place.)
1567 void fastcall
sched_exit(task_t
*p
)
1569 unsigned long flags
;
1573 * If the child was a (relative-) CPU hog then decrease
1574 * the sleep_avg of the parent as well.
1576 rq
= task_rq_lock(p
->parent
, &flags
);
1577 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1578 p
->parent
->time_slice
+= p
->time_slice
;
1579 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1580 p
->parent
->time_slice
= task_timeslice(p
);
1582 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1583 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1584 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1586 task_rq_unlock(rq
, &flags
);
1590 * prepare_task_switch - prepare to switch tasks
1591 * @rq: the runqueue preparing to switch
1592 * @next: the task we are going to switch to.
1594 * This is called with the rq lock held and interrupts off. It must
1595 * be paired with a subsequent finish_task_switch after the context
1598 * prepare_task_switch sets up locking and calls architecture specific
1601 static inline void prepare_task_switch(runqueue_t
*rq
, task_t
*next
)
1603 prepare_lock_switch(rq
, next
);
1604 prepare_arch_switch(next
);
1608 * finish_task_switch - clean up after a task-switch
1609 * @rq: runqueue associated with task-switch
1610 * @prev: the thread we just switched away from.
1612 * finish_task_switch must be called after the context switch, paired
1613 * with a prepare_task_switch call before the context switch.
1614 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1615 * and do any other architecture-specific cleanup actions.
1617 * Note that we may have delayed dropping an mm in context_switch(). If
1618 * so, we finish that here outside of the runqueue lock. (Doing it
1619 * with the lock held can cause deadlocks; see schedule() for
1622 static inline void finish_task_switch(runqueue_t
*rq
, task_t
*prev
)
1623 __releases(rq
->lock
)
1625 struct mm_struct
*mm
= rq
->prev_mm
;
1626 unsigned long prev_task_flags
;
1631 * A task struct has one reference for the use as "current".
1632 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1633 * calls schedule one last time. The schedule call will never return,
1634 * and the scheduled task must drop that reference.
1635 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1636 * still held, otherwise prev could be scheduled on another cpu, die
1637 * there before we look at prev->state, and then the reference would
1639 * Manfred Spraul <manfred@colorfullife.com>
1641 prev_task_flags
= prev
->flags
;
1642 finish_arch_switch(prev
);
1643 finish_lock_switch(rq
, prev
);
1646 if (unlikely(prev_task_flags
& PF_DEAD
))
1647 put_task_struct(prev
);
1651 * schedule_tail - first thing a freshly forked thread must call.
1652 * @prev: the thread we just switched away from.
1654 asmlinkage
void schedule_tail(task_t
*prev
)
1655 __releases(rq
->lock
)
1657 runqueue_t
*rq
= this_rq();
1658 finish_task_switch(rq
, prev
);
1659 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1660 /* In this case, finish_task_switch does not reenable preemption */
1663 if (current
->set_child_tid
)
1664 put_user(current
->pid
, current
->set_child_tid
);
1668 * context_switch - switch to the new MM and the new
1669 * thread's register state.
1672 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1674 struct mm_struct
*mm
= next
->mm
;
1675 struct mm_struct
*oldmm
= prev
->active_mm
;
1677 if (unlikely(!mm
)) {
1678 next
->active_mm
= oldmm
;
1679 atomic_inc(&oldmm
->mm_count
);
1680 enter_lazy_tlb(oldmm
, next
);
1682 switch_mm(oldmm
, mm
, next
);
1684 if (unlikely(!prev
->mm
)) {
1685 prev
->active_mm
= NULL
;
1686 WARN_ON(rq
->prev_mm
);
1687 rq
->prev_mm
= oldmm
;
1690 /* Here we just switch the register state and the stack. */
1691 switch_to(prev
, next
, prev
);
1697 * nr_running, nr_uninterruptible and nr_context_switches:
1699 * externally visible scheduler statistics: current number of runnable
1700 * threads, current number of uninterruptible-sleeping threads, total
1701 * number of context switches performed since bootup.
1703 unsigned long nr_running(void)
1705 unsigned long i
, sum
= 0;
1707 for_each_online_cpu(i
)
1708 sum
+= cpu_rq(i
)->nr_running
;
1713 unsigned long nr_uninterruptible(void)
1715 unsigned long i
, sum
= 0;
1718 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1721 * Since we read the counters lockless, it might be slightly
1722 * inaccurate. Do not allow it to go below zero though:
1724 if (unlikely((long)sum
< 0))
1730 unsigned long long nr_context_switches(void)
1732 unsigned long long i
, sum
= 0;
1735 sum
+= cpu_rq(i
)->nr_switches
;
1740 unsigned long nr_iowait(void)
1742 unsigned long i
, sum
= 0;
1745 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1753 * double_rq_lock - safely lock two runqueues
1755 * Note this does not disable interrupts like task_rq_lock,
1756 * you need to do so manually before calling.
1758 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1759 __acquires(rq1
->lock
)
1760 __acquires(rq2
->lock
)
1763 spin_lock(&rq1
->lock
);
1764 __acquire(rq2
->lock
); /* Fake it out ;) */
1767 spin_lock(&rq1
->lock
);
1768 spin_lock(&rq2
->lock
);
1770 spin_lock(&rq2
->lock
);
1771 spin_lock(&rq1
->lock
);
1777 * double_rq_unlock - safely unlock two runqueues
1779 * Note this does not restore interrupts like task_rq_unlock,
1780 * you need to do so manually after calling.
1782 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1783 __releases(rq1
->lock
)
1784 __releases(rq2
->lock
)
1786 spin_unlock(&rq1
->lock
);
1788 spin_unlock(&rq2
->lock
);
1790 __release(rq2
->lock
);
1794 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1796 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1797 __releases(this_rq
->lock
)
1798 __acquires(busiest
->lock
)
1799 __acquires(this_rq
->lock
)
1801 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1802 if (busiest
< this_rq
) {
1803 spin_unlock(&this_rq
->lock
);
1804 spin_lock(&busiest
->lock
);
1805 spin_lock(&this_rq
->lock
);
1807 spin_lock(&busiest
->lock
);
1812 * If dest_cpu is allowed for this process, migrate the task to it.
1813 * This is accomplished by forcing the cpu_allowed mask to only
1814 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1815 * the cpu_allowed mask is restored.
1817 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1819 migration_req_t req
;
1821 unsigned long flags
;
1823 rq
= task_rq_lock(p
, &flags
);
1824 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1825 || unlikely(cpu_is_offline(dest_cpu
)))
1828 /* force the process onto the specified CPU */
1829 if (migrate_task(p
, dest_cpu
, &req
)) {
1830 /* Need to wait for migration thread (might exit: take ref). */
1831 struct task_struct
*mt
= rq
->migration_thread
;
1832 get_task_struct(mt
);
1833 task_rq_unlock(rq
, &flags
);
1834 wake_up_process(mt
);
1835 put_task_struct(mt
);
1836 wait_for_completion(&req
.done
);
1840 task_rq_unlock(rq
, &flags
);
1844 * sched_exec - execve() is a valuable balancing opportunity, because at
1845 * this point the task has the smallest effective memory and cache footprint.
1847 void sched_exec(void)
1849 int new_cpu
, this_cpu
= get_cpu();
1850 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
1852 if (new_cpu
!= this_cpu
)
1853 sched_migrate_task(current
, new_cpu
);
1857 * pull_task - move a task from a remote runqueue to the local runqueue.
1858 * Both runqueues must be locked.
1861 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1862 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1864 dequeue_task(p
, src_array
);
1865 dec_nr_running(p
, src_rq
);
1866 set_task_cpu(p
, this_cpu
);
1867 inc_nr_running(p
, this_rq
);
1868 enqueue_task(p
, this_array
);
1869 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1870 + this_rq
->timestamp_last_tick
;
1872 * Note that idle threads have a prio of MAX_PRIO, for this test
1873 * to be always true for them.
1875 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1876 resched_task(this_rq
->curr
);
1880 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1883 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1884 struct sched_domain
*sd
, enum idle_type idle
,
1888 * We do not migrate tasks that are:
1889 * 1) running (obviously), or
1890 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1891 * 3) are cache-hot on their current CPU.
1893 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1897 if (task_running(rq
, p
))
1901 * Aggressive migration if:
1902 * 1) task is cache cold, or
1903 * 2) too many balance attempts have failed.
1906 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1909 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1915 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1916 * as part of a balancing operation within "domain". Returns the number of
1919 * Called with both runqueues locked.
1921 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1922 unsigned long max_nr_move
, struct sched_domain
*sd
,
1923 enum idle_type idle
, int *all_pinned
)
1925 prio_array_t
*array
, *dst_array
;
1926 struct list_head
*head
, *curr
;
1927 int idx
, pulled
= 0, pinned
= 0;
1930 if (max_nr_move
== 0)
1936 * We first consider expired tasks. Those will likely not be
1937 * executed in the near future, and they are most likely to
1938 * be cache-cold, thus switching CPUs has the least effect
1941 if (busiest
->expired
->nr_active
) {
1942 array
= busiest
->expired
;
1943 dst_array
= this_rq
->expired
;
1945 array
= busiest
->active
;
1946 dst_array
= this_rq
->active
;
1950 /* Start searching at priority 0: */
1954 idx
= sched_find_first_bit(array
->bitmap
);
1956 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1957 if (idx
>= MAX_PRIO
) {
1958 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1959 array
= busiest
->active
;
1960 dst_array
= this_rq
->active
;
1966 head
= array
->queue
+ idx
;
1969 tmp
= list_entry(curr
, task_t
, run_list
);
1973 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1980 #ifdef CONFIG_SCHEDSTATS
1981 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1982 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1985 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1988 /* We only want to steal up to the prescribed number of tasks. */
1989 if (pulled
< max_nr_move
) {
1997 * Right now, this is the only place pull_task() is called,
1998 * so we can safely collect pull_task() stats here rather than
1999 * inside pull_task().
2001 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2004 *all_pinned
= pinned
;
2009 * find_busiest_group finds and returns the busiest CPU group within the
2010 * domain. It calculates and returns the number of tasks which should be
2011 * moved to restore balance via the imbalance parameter.
2013 static struct sched_group
*
2014 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2015 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
)
2017 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2018 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2019 unsigned long max_pull
;
2022 max_load
= this_load
= total_load
= total_pwr
= 0;
2023 if (idle
== NOT_IDLE
)
2024 load_idx
= sd
->busy_idx
;
2025 else if (idle
== NEWLY_IDLE
)
2026 load_idx
= sd
->newidle_idx
;
2028 load_idx
= sd
->idle_idx
;
2035 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2037 /* Tally up the load of all CPUs in the group */
2040 for_each_cpu_mask(i
, group
->cpumask
) {
2041 if (*sd_idle
&& !idle_cpu(i
))
2044 /* Bias balancing toward cpus of our domain */
2046 load
= __target_load(i
, load_idx
, idle
);
2048 load
= __source_load(i
, load_idx
, idle
);
2053 total_load
+= avg_load
;
2054 total_pwr
+= group
->cpu_power
;
2056 /* Adjust by relative CPU power of the group */
2057 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2060 this_load
= avg_load
;
2062 } else if (avg_load
> max_load
) {
2063 max_load
= avg_load
;
2066 group
= group
->next
;
2067 } while (group
!= sd
->groups
);
2069 if (!busiest
|| this_load
>= max_load
|| max_load
<= SCHED_LOAD_SCALE
)
2072 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2074 if (this_load
>= avg_load
||
2075 100*max_load
<= sd
->imbalance_pct
*this_load
)
2079 * We're trying to get all the cpus to the average_load, so we don't
2080 * want to push ourselves above the average load, nor do we wish to
2081 * reduce the max loaded cpu below the average load, as either of these
2082 * actions would just result in more rebalancing later, and ping-pong
2083 * tasks around. Thus we look for the minimum possible imbalance.
2084 * Negative imbalances (*we* are more loaded than anyone else) will
2085 * be counted as no imbalance for these purposes -- we can't fix that
2086 * by pulling tasks to us. Be careful of negative numbers as they'll
2087 * appear as very large values with unsigned longs.
2090 /* Don't want to pull so many tasks that a group would go idle */
2091 max_pull
= min(max_load
- avg_load
, max_load
- SCHED_LOAD_SCALE
);
2093 /* How much load to actually move to equalise the imbalance */
2094 *imbalance
= min(max_pull
* busiest
->cpu_power
,
2095 (avg_load
- this_load
) * this->cpu_power
)
2098 if (*imbalance
< SCHED_LOAD_SCALE
) {
2099 unsigned long pwr_now
= 0, pwr_move
= 0;
2102 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
2108 * OK, we don't have enough imbalance to justify moving tasks,
2109 * however we may be able to increase total CPU power used by
2113 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
2114 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
2115 pwr_now
/= SCHED_LOAD_SCALE
;
2117 /* Amount of load we'd subtract */
2118 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
2120 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
2123 /* Amount of load we'd add */
2124 if (max_load
*busiest
->cpu_power
<
2125 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
2126 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
2128 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
2129 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
2130 pwr_move
/= SCHED_LOAD_SCALE
;
2132 /* Move if we gain throughput */
2133 if (pwr_move
<= pwr_now
)
2140 /* Get rid of the scaling factor, rounding down as we divide */
2141 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
2151 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2153 static runqueue_t
*find_busiest_queue(struct sched_group
*group
,
2154 enum idle_type idle
)
2156 unsigned long load
, max_load
= 0;
2157 runqueue_t
*busiest
= NULL
;
2160 for_each_cpu_mask(i
, group
->cpumask
) {
2161 load
= __source_load(i
, 0, idle
);
2163 if (load
> max_load
) {
2165 busiest
= cpu_rq(i
);
2173 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2174 * so long as it is large enough.
2176 #define MAX_PINNED_INTERVAL 512
2179 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2180 * tasks if there is an imbalance.
2182 * Called with this_rq unlocked.
2184 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
2185 struct sched_domain
*sd
, enum idle_type idle
)
2187 struct sched_group
*group
;
2188 runqueue_t
*busiest
;
2189 unsigned long imbalance
;
2190 int nr_moved
, all_pinned
= 0;
2191 int active_balance
= 0;
2194 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2197 schedstat_inc(sd
, lb_cnt
[idle
]);
2199 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
);
2201 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2205 busiest
= find_busiest_queue(group
, idle
);
2207 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2211 BUG_ON(busiest
== this_rq
);
2213 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2216 if (busiest
->nr_running
> 1) {
2218 * Attempt to move tasks. If find_busiest_group has found
2219 * an imbalance but busiest->nr_running <= 1, the group is
2220 * still unbalanced. nr_moved simply stays zero, so it is
2221 * correctly treated as an imbalance.
2223 double_rq_lock(this_rq
, busiest
);
2224 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2225 imbalance
, sd
, idle
, &all_pinned
);
2226 double_rq_unlock(this_rq
, busiest
);
2228 /* All tasks on this runqueue were pinned by CPU affinity */
2229 if (unlikely(all_pinned
))
2234 schedstat_inc(sd
, lb_failed
[idle
]);
2235 sd
->nr_balance_failed
++;
2237 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2239 spin_lock(&busiest
->lock
);
2241 /* don't kick the migration_thread, if the curr
2242 * task on busiest cpu can't be moved to this_cpu
2244 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2245 spin_unlock(&busiest
->lock
);
2247 goto out_one_pinned
;
2250 if (!busiest
->active_balance
) {
2251 busiest
->active_balance
= 1;
2252 busiest
->push_cpu
= this_cpu
;
2255 spin_unlock(&busiest
->lock
);
2257 wake_up_process(busiest
->migration_thread
);
2260 * We've kicked active balancing, reset the failure
2263 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2266 sd
->nr_balance_failed
= 0;
2268 if (likely(!active_balance
)) {
2269 /* We were unbalanced, so reset the balancing interval */
2270 sd
->balance_interval
= sd
->min_interval
;
2273 * If we've begun active balancing, start to back off. This
2274 * case may not be covered by the all_pinned logic if there
2275 * is only 1 task on the busy runqueue (because we don't call
2278 if (sd
->balance_interval
< sd
->max_interval
)
2279 sd
->balance_interval
*= 2;
2282 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2287 schedstat_inc(sd
, lb_balanced
[idle
]);
2289 sd
->nr_balance_failed
= 0;
2292 /* tune up the balancing interval */
2293 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2294 (sd
->balance_interval
< sd
->max_interval
))
2295 sd
->balance_interval
*= 2;
2297 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2303 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2304 * tasks if there is an imbalance.
2306 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2307 * this_rq is locked.
2309 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2310 struct sched_domain
*sd
)
2312 struct sched_group
*group
;
2313 runqueue_t
*busiest
= NULL
;
2314 unsigned long imbalance
;
2318 if (sd
->flags
& SD_SHARE_CPUPOWER
)
2321 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2322 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
, &sd_idle
);
2324 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2328 busiest
= find_busiest_queue(group
, NEWLY_IDLE
);
2330 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2334 BUG_ON(busiest
== this_rq
);
2336 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2339 if (busiest
->nr_running
> 1) {
2340 /* Attempt to move tasks */
2341 double_lock_balance(this_rq
, busiest
);
2342 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2343 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2344 spin_unlock(&busiest
->lock
);
2348 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2349 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2352 sd
->nr_balance_failed
= 0;
2357 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2358 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2360 sd
->nr_balance_failed
= 0;
2365 * idle_balance is called by schedule() if this_cpu is about to become
2366 * idle. Attempts to pull tasks from other CPUs.
2368 static inline void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2370 struct sched_domain
*sd
;
2372 for_each_domain(this_cpu
, sd
) {
2373 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2374 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2375 /* We've pulled tasks over so stop searching */
2383 * active_load_balance is run by migration threads. It pushes running tasks
2384 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2385 * running on each physical CPU where possible, and avoids physical /
2386 * logical imbalances.
2388 * Called with busiest_rq locked.
2390 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2392 struct sched_domain
*sd
;
2393 runqueue_t
*target_rq
;
2394 int target_cpu
= busiest_rq
->push_cpu
;
2396 if (busiest_rq
->nr_running
<= 1)
2397 /* no task to move */
2400 target_rq
= cpu_rq(target_cpu
);
2403 * This condition is "impossible", if it occurs
2404 * we need to fix it. Originally reported by
2405 * Bjorn Helgaas on a 128-cpu setup.
2407 BUG_ON(busiest_rq
== target_rq
);
2409 /* move a task from busiest_rq to target_rq */
2410 double_lock_balance(busiest_rq
, target_rq
);
2412 /* Search for an sd spanning us and the target CPU. */
2413 for_each_domain(target_cpu
, sd
)
2414 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2415 cpu_isset(busiest_cpu
, sd
->span
))
2418 if (unlikely(sd
== NULL
))
2421 schedstat_inc(sd
, alb_cnt
);
2423 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1, sd
, SCHED_IDLE
, NULL
))
2424 schedstat_inc(sd
, alb_pushed
);
2426 schedstat_inc(sd
, alb_failed
);
2428 spin_unlock(&target_rq
->lock
);
2432 * rebalance_tick will get called every timer tick, on every CPU.
2434 * It checks each scheduling domain to see if it is due to be balanced,
2435 * and initiates a balancing operation if so.
2437 * Balancing parameters are set up in arch_init_sched_domains.
2440 /* Don't have all balancing operations going off at once */
2441 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2443 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2444 enum idle_type idle
)
2446 unsigned long old_load
, this_load
;
2447 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2448 struct sched_domain
*sd
;
2451 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2452 /* Update our load */
2453 for (i
= 0; i
< 3; i
++) {
2454 unsigned long new_load
= this_load
;
2456 old_load
= this_rq
->cpu_load
[i
];
2458 * Round up the averaging division if load is increasing. This
2459 * prevents us from getting stuck on 9 if the load is 10, for
2462 if (new_load
> old_load
)
2463 new_load
+= scale
-1;
2464 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2467 for_each_domain(this_cpu
, sd
) {
2468 unsigned long interval
;
2470 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2473 interval
= sd
->balance_interval
;
2474 if (idle
!= SCHED_IDLE
)
2475 interval
*= sd
->busy_factor
;
2477 /* scale ms to jiffies */
2478 interval
= msecs_to_jiffies(interval
);
2479 if (unlikely(!interval
))
2482 if (j
- sd
->last_balance
>= interval
) {
2483 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2485 * We've pulled tasks over so either we're no
2486 * longer idle, or one of our SMT siblings is
2491 sd
->last_balance
+= interval
;
2497 * on UP we do not need to balance between CPUs:
2499 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2502 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2507 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2510 #ifdef CONFIG_SCHED_SMT
2511 spin_lock(&rq
->lock
);
2513 * If an SMT sibling task has been put to sleep for priority
2514 * reasons reschedule the idle task to see if it can now run.
2516 if (rq
->nr_running
) {
2517 resched_task(rq
->idle
);
2520 spin_unlock(&rq
->lock
);
2525 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2527 EXPORT_PER_CPU_SYMBOL(kstat
);
2530 * This is called on clock ticks and on context switches.
2531 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2533 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2534 unsigned long long now
)
2536 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2537 p
->sched_time
+= now
- last
;
2541 * Return current->sched_time plus any more ns on the sched_clock
2542 * that have not yet been banked.
2544 unsigned long long current_sched_time(const task_t
*tsk
)
2546 unsigned long long ns
;
2547 unsigned long flags
;
2548 local_irq_save(flags
);
2549 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2550 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2551 local_irq_restore(flags
);
2556 * We place interactive tasks back into the active array, if possible.
2558 * To guarantee that this does not starve expired tasks we ignore the
2559 * interactivity of a task if the first expired task had to wait more
2560 * than a 'reasonable' amount of time. This deadline timeout is
2561 * load-dependent, as the frequency of array switched decreases with
2562 * increasing number of running tasks. We also ignore the interactivity
2563 * if a better static_prio task has expired:
2565 #define EXPIRED_STARVING(rq) \
2566 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2567 (jiffies - (rq)->expired_timestamp >= \
2568 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2569 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2572 * Account user cpu time to a process.
2573 * @p: the process that the cpu time gets accounted to
2574 * @hardirq_offset: the offset to subtract from hardirq_count()
2575 * @cputime: the cpu time spent in user space since the last update
2577 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2579 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2582 p
->utime
= cputime_add(p
->utime
, cputime
);
2584 /* Add user time to cpustat. */
2585 tmp
= cputime_to_cputime64(cputime
);
2586 if (TASK_NICE(p
) > 0)
2587 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2589 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2593 * Account system cpu time to a process.
2594 * @p: the process that the cpu time gets accounted to
2595 * @hardirq_offset: the offset to subtract from hardirq_count()
2596 * @cputime: the cpu time spent in kernel space since the last update
2598 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2601 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2602 runqueue_t
*rq
= this_rq();
2605 p
->stime
= cputime_add(p
->stime
, cputime
);
2607 /* Add system time to cpustat. */
2608 tmp
= cputime_to_cputime64(cputime
);
2609 if (hardirq_count() - hardirq_offset
)
2610 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2611 else if (softirq_count())
2612 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2613 else if (p
!= rq
->idle
)
2614 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2615 else if (atomic_read(&rq
->nr_iowait
) > 0)
2616 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2618 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2619 /* Account for system time used */
2620 acct_update_integrals(p
);
2624 * Account for involuntary wait time.
2625 * @p: the process from which the cpu time has been stolen
2626 * @steal: the cpu time spent in involuntary wait
2628 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2630 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2631 cputime64_t tmp
= cputime_to_cputime64(steal
);
2632 runqueue_t
*rq
= this_rq();
2634 if (p
== rq
->idle
) {
2635 p
->stime
= cputime_add(p
->stime
, steal
);
2636 if (atomic_read(&rq
->nr_iowait
) > 0)
2637 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2639 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2641 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2645 * This function gets called by the timer code, with HZ frequency.
2646 * We call it with interrupts disabled.
2648 * It also gets called by the fork code, when changing the parent's
2651 void scheduler_tick(void)
2653 int cpu
= smp_processor_id();
2654 runqueue_t
*rq
= this_rq();
2655 task_t
*p
= current
;
2656 unsigned long long now
= sched_clock();
2658 update_cpu_clock(p
, rq
, now
);
2660 rq
->timestamp_last_tick
= now
;
2662 if (p
== rq
->idle
) {
2663 if (wake_priority_sleeper(rq
))
2665 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2669 /* Task might have expired already, but not scheduled off yet */
2670 if (p
->array
!= rq
->active
) {
2671 set_tsk_need_resched(p
);
2674 spin_lock(&rq
->lock
);
2676 * The task was running during this tick - update the
2677 * time slice counter. Note: we do not update a thread's
2678 * priority until it either goes to sleep or uses up its
2679 * timeslice. This makes it possible for interactive tasks
2680 * to use up their timeslices at their highest priority levels.
2684 * RR tasks need a special form of timeslice management.
2685 * FIFO tasks have no timeslices.
2687 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2688 p
->time_slice
= task_timeslice(p
);
2689 p
->first_time_slice
= 0;
2690 set_tsk_need_resched(p
);
2692 /* put it at the end of the queue: */
2693 requeue_task(p
, rq
->active
);
2697 if (!--p
->time_slice
) {
2698 dequeue_task(p
, rq
->active
);
2699 set_tsk_need_resched(p
);
2700 p
->prio
= effective_prio(p
);
2701 p
->time_slice
= task_timeslice(p
);
2702 p
->first_time_slice
= 0;
2704 if (!rq
->expired_timestamp
)
2705 rq
->expired_timestamp
= jiffies
;
2706 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2707 enqueue_task(p
, rq
->expired
);
2708 if (p
->static_prio
< rq
->best_expired_prio
)
2709 rq
->best_expired_prio
= p
->static_prio
;
2711 enqueue_task(p
, rq
->active
);
2714 * Prevent a too long timeslice allowing a task to monopolize
2715 * the CPU. We do this by splitting up the timeslice into
2718 * Note: this does not mean the task's timeslices expire or
2719 * get lost in any way, they just might be preempted by
2720 * another task of equal priority. (one with higher
2721 * priority would have preempted this task already.) We
2722 * requeue this task to the end of the list on this priority
2723 * level, which is in essence a round-robin of tasks with
2726 * This only applies to tasks in the interactive
2727 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2729 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2730 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2731 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2732 (p
->array
== rq
->active
)) {
2734 requeue_task(p
, rq
->active
);
2735 set_tsk_need_resched(p
);
2739 spin_unlock(&rq
->lock
);
2741 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2744 #ifdef CONFIG_SCHED_SMT
2745 static inline void wakeup_busy_runqueue(runqueue_t
*rq
)
2747 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
2748 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
2749 resched_task(rq
->idle
);
2752 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2754 struct sched_domain
*tmp
, *sd
= NULL
;
2755 cpumask_t sibling_map
;
2758 for_each_domain(this_cpu
, tmp
)
2759 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2766 * Unlock the current runqueue because we have to lock in
2767 * CPU order to avoid deadlocks. Caller knows that we might
2768 * unlock. We keep IRQs disabled.
2770 spin_unlock(&this_rq
->lock
);
2772 sibling_map
= sd
->span
;
2774 for_each_cpu_mask(i
, sibling_map
)
2775 spin_lock(&cpu_rq(i
)->lock
);
2777 * We clear this CPU from the mask. This both simplifies the
2778 * inner loop and keps this_rq locked when we exit:
2780 cpu_clear(this_cpu
, sibling_map
);
2782 for_each_cpu_mask(i
, sibling_map
) {
2783 runqueue_t
*smt_rq
= cpu_rq(i
);
2785 wakeup_busy_runqueue(smt_rq
);
2788 for_each_cpu_mask(i
, sibling_map
)
2789 spin_unlock(&cpu_rq(i
)->lock
);
2791 * We exit with this_cpu's rq still held and IRQs
2797 * number of 'lost' timeslices this task wont be able to fully
2798 * utilize, if another task runs on a sibling. This models the
2799 * slowdown effect of other tasks running on siblings:
2801 static inline unsigned long smt_slice(task_t
*p
, struct sched_domain
*sd
)
2803 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
2806 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2808 struct sched_domain
*tmp
, *sd
= NULL
;
2809 cpumask_t sibling_map
;
2810 prio_array_t
*array
;
2814 for_each_domain(this_cpu
, tmp
)
2815 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2822 * The same locking rules and details apply as for
2823 * wake_sleeping_dependent():
2825 spin_unlock(&this_rq
->lock
);
2826 sibling_map
= sd
->span
;
2827 for_each_cpu_mask(i
, sibling_map
)
2828 spin_lock(&cpu_rq(i
)->lock
);
2829 cpu_clear(this_cpu
, sibling_map
);
2832 * Establish next task to be run - it might have gone away because
2833 * we released the runqueue lock above:
2835 if (!this_rq
->nr_running
)
2837 array
= this_rq
->active
;
2838 if (!array
->nr_active
)
2839 array
= this_rq
->expired
;
2840 BUG_ON(!array
->nr_active
);
2842 p
= list_entry(array
->queue
[sched_find_first_bit(array
->bitmap
)].next
,
2845 for_each_cpu_mask(i
, sibling_map
) {
2846 runqueue_t
*smt_rq
= cpu_rq(i
);
2847 task_t
*smt_curr
= smt_rq
->curr
;
2849 /* Kernel threads do not participate in dependent sleeping */
2850 if (!p
->mm
|| !smt_curr
->mm
|| rt_task(p
))
2851 goto check_smt_task
;
2854 * If a user task with lower static priority than the
2855 * running task on the SMT sibling is trying to schedule,
2856 * delay it till there is proportionately less timeslice
2857 * left of the sibling task to prevent a lower priority
2858 * task from using an unfair proportion of the
2859 * physical cpu's resources. -ck
2861 if (rt_task(smt_curr
)) {
2863 * With real time tasks we run non-rt tasks only
2864 * per_cpu_gain% of the time.
2866 if ((jiffies
% DEF_TIMESLICE
) >
2867 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2870 if (smt_curr
->static_prio
< p
->static_prio
&&
2871 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2872 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
2876 if ((!smt_curr
->mm
&& smt_curr
!= smt_rq
->idle
) ||
2880 wakeup_busy_runqueue(smt_rq
);
2885 * Reschedule a lower priority task on the SMT sibling for
2886 * it to be put to sleep, or wake it up if it has been put to
2887 * sleep for priority reasons to see if it should run now.
2890 if ((jiffies
% DEF_TIMESLICE
) >
2891 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2892 resched_task(smt_curr
);
2894 if (TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2895 smt_slice(p
, sd
) > task_timeslice(smt_curr
))
2896 resched_task(smt_curr
);
2898 wakeup_busy_runqueue(smt_rq
);
2902 for_each_cpu_mask(i
, sibling_map
)
2903 spin_unlock(&cpu_rq(i
)->lock
);
2907 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2911 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2917 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2919 void fastcall
add_preempt_count(int val
)
2924 BUG_ON((preempt_count() < 0));
2925 preempt_count() += val
;
2927 * Spinlock count overflowing soon?
2929 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2931 EXPORT_SYMBOL(add_preempt_count
);
2933 void fastcall
sub_preempt_count(int val
)
2938 BUG_ON(val
> preempt_count());
2940 * Is the spinlock portion underflowing?
2942 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2943 preempt_count() -= val
;
2945 EXPORT_SYMBOL(sub_preempt_count
);
2950 * schedule() is the main scheduler function.
2952 asmlinkage
void __sched
schedule(void)
2955 task_t
*prev
, *next
;
2957 prio_array_t
*array
;
2958 struct list_head
*queue
;
2959 unsigned long long now
;
2960 unsigned long run_time
;
2961 int cpu
, idx
, new_prio
;
2964 * Test if we are atomic. Since do_exit() needs to call into
2965 * schedule() atomically, we ignore that path for now.
2966 * Otherwise, whine if we are scheduling when we should not be.
2968 if (likely(!current
->exit_state
)) {
2969 if (unlikely(in_atomic())) {
2970 printk(KERN_ERR
"scheduling while atomic: "
2972 current
->comm
, preempt_count(), current
->pid
);
2976 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2981 release_kernel_lock(prev
);
2982 need_resched_nonpreemptible
:
2986 * The idle thread is not allowed to schedule!
2987 * Remove this check after it has been exercised a bit.
2989 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2990 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
2994 schedstat_inc(rq
, sched_cnt
);
2995 now
= sched_clock();
2996 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
2997 run_time
= now
- prev
->timestamp
;
2998 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
3001 run_time
= NS_MAX_SLEEP_AVG
;
3004 * Tasks charged proportionately less run_time at high sleep_avg to
3005 * delay them losing their interactive status
3007 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
3009 spin_lock_irq(&rq
->lock
);
3011 if (unlikely(prev
->flags
& PF_DEAD
))
3012 prev
->state
= EXIT_DEAD
;
3014 switch_count
= &prev
->nivcsw
;
3015 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3016 switch_count
= &prev
->nvcsw
;
3017 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3018 unlikely(signal_pending(prev
))))
3019 prev
->state
= TASK_RUNNING
;
3021 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
3022 rq
->nr_uninterruptible
++;
3023 deactivate_task(prev
, rq
);
3027 cpu
= smp_processor_id();
3028 if (unlikely(!rq
->nr_running
)) {
3030 idle_balance(cpu
, rq
);
3031 if (!rq
->nr_running
) {
3033 rq
->expired_timestamp
= 0;
3034 wake_sleeping_dependent(cpu
, rq
);
3036 * wake_sleeping_dependent() might have released
3037 * the runqueue, so break out if we got new
3040 if (!rq
->nr_running
)
3044 if (dependent_sleeper(cpu
, rq
)) {
3049 * dependent_sleeper() releases and reacquires the runqueue
3050 * lock, hence go into the idle loop if the rq went
3053 if (unlikely(!rq
->nr_running
))
3058 if (unlikely(!array
->nr_active
)) {
3060 * Switch the active and expired arrays.
3062 schedstat_inc(rq
, sched_switch
);
3063 rq
->active
= rq
->expired
;
3064 rq
->expired
= array
;
3066 rq
->expired_timestamp
= 0;
3067 rq
->best_expired_prio
= MAX_PRIO
;
3070 idx
= sched_find_first_bit(array
->bitmap
);
3071 queue
= array
->queue
+ idx
;
3072 next
= list_entry(queue
->next
, task_t
, run_list
);
3074 if (!rt_task(next
) && next
->activated
> 0) {
3075 unsigned long long delta
= now
- next
->timestamp
;
3076 if (unlikely((long long)(now
- next
->timestamp
) < 0))
3079 if (next
->activated
== 1)
3080 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
3082 array
= next
->array
;
3083 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
3085 if (unlikely(next
->prio
!= new_prio
)) {
3086 dequeue_task(next
, array
);
3087 next
->prio
= new_prio
;
3088 enqueue_task(next
, array
);
3090 requeue_task(next
, array
);
3092 next
->activated
= 0;
3094 if (next
== rq
->idle
)
3095 schedstat_inc(rq
, sched_goidle
);
3097 prefetch_stack(next
);
3098 clear_tsk_need_resched(prev
);
3099 rcu_qsctr_inc(task_cpu(prev
));
3101 update_cpu_clock(prev
, rq
, now
);
3103 prev
->sleep_avg
-= run_time
;
3104 if ((long)prev
->sleep_avg
<= 0)
3105 prev
->sleep_avg
= 0;
3106 prev
->timestamp
= prev
->last_ran
= now
;
3108 sched_info_switch(prev
, next
);
3109 if (likely(prev
!= next
)) {
3110 next
->timestamp
= now
;
3115 prepare_task_switch(rq
, next
);
3116 prev
= context_switch(rq
, prev
, next
);
3119 * this_rq must be evaluated again because prev may have moved
3120 * CPUs since it called schedule(), thus the 'rq' on its stack
3121 * frame will be invalid.
3123 finish_task_switch(this_rq(), prev
);
3125 spin_unlock_irq(&rq
->lock
);
3128 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3129 goto need_resched_nonpreemptible
;
3130 preempt_enable_no_resched();
3131 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3135 EXPORT_SYMBOL(schedule
);
3137 #ifdef CONFIG_PREEMPT
3139 * this is is the entry point to schedule() from in-kernel preemption
3140 * off of preempt_enable. Kernel preemptions off return from interrupt
3141 * occur there and call schedule directly.
3143 asmlinkage
void __sched
preempt_schedule(void)
3145 struct thread_info
*ti
= current_thread_info();
3146 #ifdef CONFIG_PREEMPT_BKL
3147 struct task_struct
*task
= current
;
3148 int saved_lock_depth
;
3151 * If there is a non-zero preempt_count or interrupts are disabled,
3152 * we do not want to preempt the current task. Just return..
3154 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
3158 add_preempt_count(PREEMPT_ACTIVE
);
3160 * We keep the big kernel semaphore locked, but we
3161 * clear ->lock_depth so that schedule() doesnt
3162 * auto-release the semaphore:
3164 #ifdef CONFIG_PREEMPT_BKL
3165 saved_lock_depth
= task
->lock_depth
;
3166 task
->lock_depth
= -1;
3169 #ifdef CONFIG_PREEMPT_BKL
3170 task
->lock_depth
= saved_lock_depth
;
3172 sub_preempt_count(PREEMPT_ACTIVE
);
3174 /* we could miss a preemption opportunity between schedule and now */
3176 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3180 EXPORT_SYMBOL(preempt_schedule
);
3183 * this is is the entry point to schedule() from kernel preemption
3184 * off of irq context.
3185 * Note, that this is called and return with irqs disabled. This will
3186 * protect us against recursive calling from irq.
3188 asmlinkage
void __sched
preempt_schedule_irq(void)
3190 struct thread_info
*ti
= current_thread_info();
3191 #ifdef CONFIG_PREEMPT_BKL
3192 struct task_struct
*task
= current
;
3193 int saved_lock_depth
;
3195 /* Catch callers which need to be fixed*/
3196 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3199 add_preempt_count(PREEMPT_ACTIVE
);
3201 * We keep the big kernel semaphore locked, but we
3202 * clear ->lock_depth so that schedule() doesnt
3203 * auto-release the semaphore:
3205 #ifdef CONFIG_PREEMPT_BKL
3206 saved_lock_depth
= task
->lock_depth
;
3207 task
->lock_depth
= -1;
3211 local_irq_disable();
3212 #ifdef CONFIG_PREEMPT_BKL
3213 task
->lock_depth
= saved_lock_depth
;
3215 sub_preempt_count(PREEMPT_ACTIVE
);
3217 /* we could miss a preemption opportunity between schedule and now */
3219 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3223 #endif /* CONFIG_PREEMPT */
3225 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3228 task_t
*p
= curr
->private;
3229 return try_to_wake_up(p
, mode
, sync
);
3232 EXPORT_SYMBOL(default_wake_function
);
3235 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3236 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3237 * number) then we wake all the non-exclusive tasks and one exclusive task.
3239 * There are circumstances in which we can try to wake a task which has already
3240 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3241 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3243 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3244 int nr_exclusive
, int sync
, void *key
)
3246 struct list_head
*tmp
, *next
;
3248 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3251 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3252 flags
= curr
->flags
;
3253 if (curr
->func(curr
, mode
, sync
, key
) &&
3254 (flags
& WQ_FLAG_EXCLUSIVE
) &&
3261 * __wake_up - wake up threads blocked on a waitqueue.
3263 * @mode: which threads
3264 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3265 * @key: is directly passed to the wakeup function
3267 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3268 int nr_exclusive
, void *key
)
3270 unsigned long flags
;
3272 spin_lock_irqsave(&q
->lock
, flags
);
3273 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3274 spin_unlock_irqrestore(&q
->lock
, flags
);
3277 EXPORT_SYMBOL(__wake_up
);
3280 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3282 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3284 __wake_up_common(q
, mode
, 1, 0, NULL
);
3288 * __wake_up_sync - wake up threads blocked on a waitqueue.
3290 * @mode: which threads
3291 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3293 * The sync wakeup differs that the waker knows that it will schedule
3294 * away soon, so while the target thread will be woken up, it will not
3295 * be migrated to another CPU - ie. the two threads are 'synchronized'
3296 * with each other. This can prevent needless bouncing between CPUs.
3298 * On UP it can prevent extra preemption.
3301 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3303 unsigned long flags
;
3309 if (unlikely(!nr_exclusive
))
3312 spin_lock_irqsave(&q
->lock
, flags
);
3313 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3314 spin_unlock_irqrestore(&q
->lock
, flags
);
3316 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3318 void fastcall
complete(struct completion
*x
)
3320 unsigned long flags
;
3322 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3324 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3326 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3328 EXPORT_SYMBOL(complete
);
3330 void fastcall
complete_all(struct completion
*x
)
3332 unsigned long flags
;
3334 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3335 x
->done
+= UINT_MAX
/2;
3336 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3338 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3340 EXPORT_SYMBOL(complete_all
);
3342 void fastcall __sched
wait_for_completion(struct completion
*x
)
3345 spin_lock_irq(&x
->wait
.lock
);
3347 DECLARE_WAITQUEUE(wait
, current
);
3349 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3350 __add_wait_queue_tail(&x
->wait
, &wait
);
3352 __set_current_state(TASK_UNINTERRUPTIBLE
);
3353 spin_unlock_irq(&x
->wait
.lock
);
3355 spin_lock_irq(&x
->wait
.lock
);
3357 __remove_wait_queue(&x
->wait
, &wait
);
3360 spin_unlock_irq(&x
->wait
.lock
);
3362 EXPORT_SYMBOL(wait_for_completion
);
3364 unsigned long fastcall __sched
3365 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3369 spin_lock_irq(&x
->wait
.lock
);
3371 DECLARE_WAITQUEUE(wait
, current
);
3373 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3374 __add_wait_queue_tail(&x
->wait
, &wait
);
3376 __set_current_state(TASK_UNINTERRUPTIBLE
);
3377 spin_unlock_irq(&x
->wait
.lock
);
3378 timeout
= schedule_timeout(timeout
);
3379 spin_lock_irq(&x
->wait
.lock
);
3381 __remove_wait_queue(&x
->wait
, &wait
);
3385 __remove_wait_queue(&x
->wait
, &wait
);
3389 spin_unlock_irq(&x
->wait
.lock
);
3392 EXPORT_SYMBOL(wait_for_completion_timeout
);
3394 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3400 spin_lock_irq(&x
->wait
.lock
);
3402 DECLARE_WAITQUEUE(wait
, current
);
3404 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3405 __add_wait_queue_tail(&x
->wait
, &wait
);
3407 if (signal_pending(current
)) {
3409 __remove_wait_queue(&x
->wait
, &wait
);
3412 __set_current_state(TASK_INTERRUPTIBLE
);
3413 spin_unlock_irq(&x
->wait
.lock
);
3415 spin_lock_irq(&x
->wait
.lock
);
3417 __remove_wait_queue(&x
->wait
, &wait
);
3421 spin_unlock_irq(&x
->wait
.lock
);
3425 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3427 unsigned long fastcall __sched
3428 wait_for_completion_interruptible_timeout(struct completion
*x
,
3429 unsigned long timeout
)
3433 spin_lock_irq(&x
->wait
.lock
);
3435 DECLARE_WAITQUEUE(wait
, current
);
3437 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3438 __add_wait_queue_tail(&x
->wait
, &wait
);
3440 if (signal_pending(current
)) {
3441 timeout
= -ERESTARTSYS
;
3442 __remove_wait_queue(&x
->wait
, &wait
);
3445 __set_current_state(TASK_INTERRUPTIBLE
);
3446 spin_unlock_irq(&x
->wait
.lock
);
3447 timeout
= schedule_timeout(timeout
);
3448 spin_lock_irq(&x
->wait
.lock
);
3450 __remove_wait_queue(&x
->wait
, &wait
);
3454 __remove_wait_queue(&x
->wait
, &wait
);
3458 spin_unlock_irq(&x
->wait
.lock
);
3461 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3464 #define SLEEP_ON_VAR \
3465 unsigned long flags; \
3466 wait_queue_t wait; \
3467 init_waitqueue_entry(&wait, current);
3469 #define SLEEP_ON_HEAD \
3470 spin_lock_irqsave(&q->lock,flags); \
3471 __add_wait_queue(q, &wait); \
3472 spin_unlock(&q->lock);
3474 #define SLEEP_ON_TAIL \
3475 spin_lock_irq(&q->lock); \
3476 __remove_wait_queue(q, &wait); \
3477 spin_unlock_irqrestore(&q->lock, flags);
3479 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3483 current
->state
= TASK_INTERRUPTIBLE
;
3490 EXPORT_SYMBOL(interruptible_sleep_on
);
3492 long fastcall __sched
3493 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3497 current
->state
= TASK_INTERRUPTIBLE
;
3500 timeout
= schedule_timeout(timeout
);
3506 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3508 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3512 current
->state
= TASK_UNINTERRUPTIBLE
;
3519 EXPORT_SYMBOL(sleep_on
);
3521 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3525 current
->state
= TASK_UNINTERRUPTIBLE
;
3528 timeout
= schedule_timeout(timeout
);
3534 EXPORT_SYMBOL(sleep_on_timeout
);
3536 void set_user_nice(task_t
*p
, long nice
)
3538 unsigned long flags
;
3539 prio_array_t
*array
;
3541 int old_prio
, new_prio
, delta
;
3543 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3546 * We have to be careful, if called from sys_setpriority(),
3547 * the task might be in the middle of scheduling on another CPU.
3549 rq
= task_rq_lock(p
, &flags
);
3551 * The RT priorities are set via sched_setscheduler(), but we still
3552 * allow the 'normal' nice value to be set - but as expected
3553 * it wont have any effect on scheduling until the task is
3557 p
->static_prio
= NICE_TO_PRIO(nice
);
3562 dequeue_task(p
, array
);
3563 dec_prio_bias(rq
, p
->static_prio
);
3567 new_prio
= NICE_TO_PRIO(nice
);
3568 delta
= new_prio
- old_prio
;
3569 p
->static_prio
= NICE_TO_PRIO(nice
);
3573 enqueue_task(p
, array
);
3574 inc_prio_bias(rq
, p
->static_prio
);
3576 * If the task increased its priority or is running and
3577 * lowered its priority, then reschedule its CPU:
3579 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3580 resched_task(rq
->curr
);
3583 task_rq_unlock(rq
, &flags
);
3586 EXPORT_SYMBOL(set_user_nice
);
3589 * can_nice - check if a task can reduce its nice value
3593 int can_nice(const task_t
*p
, const int nice
)
3595 /* convert nice value [19,-20] to rlimit style value [1,40] */
3596 int nice_rlim
= 20 - nice
;
3597 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3598 capable(CAP_SYS_NICE
));
3601 #ifdef __ARCH_WANT_SYS_NICE
3604 * sys_nice - change the priority of the current process.
3605 * @increment: priority increment
3607 * sys_setpriority is a more generic, but much slower function that
3608 * does similar things.
3610 asmlinkage
long sys_nice(int increment
)
3616 * Setpriority might change our priority at the same moment.
3617 * We don't have to worry. Conceptually one call occurs first
3618 * and we have a single winner.
3620 if (increment
< -40)
3625 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3631 if (increment
< 0 && !can_nice(current
, nice
))
3634 retval
= security_task_setnice(current
, nice
);
3638 set_user_nice(current
, nice
);
3645 * task_prio - return the priority value of a given task.
3646 * @p: the task in question.
3648 * This is the priority value as seen by users in /proc.
3649 * RT tasks are offset by -200. Normal tasks are centered
3650 * around 0, value goes from -16 to +15.
3652 int task_prio(const task_t
*p
)
3654 return p
->prio
- MAX_RT_PRIO
;
3658 * task_nice - return the nice value of a given task.
3659 * @p: the task in question.
3661 int task_nice(const task_t
*p
)
3663 return TASK_NICE(p
);
3665 EXPORT_SYMBOL_GPL(task_nice
);
3668 * idle_cpu - is a given cpu idle currently?
3669 * @cpu: the processor in question.
3671 int idle_cpu(int cpu
)
3673 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3677 * idle_task - return the idle task for a given cpu.
3678 * @cpu: the processor in question.
3680 task_t
*idle_task(int cpu
)
3682 return cpu_rq(cpu
)->idle
;
3686 * find_process_by_pid - find a process with a matching PID value.
3687 * @pid: the pid in question.
3689 static inline task_t
*find_process_by_pid(pid_t pid
)
3691 return pid
? find_task_by_pid(pid
) : current
;
3694 /* Actually do priority change: must hold rq lock. */
3695 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3699 p
->rt_priority
= prio
;
3700 if (policy
!= SCHED_NORMAL
)
3701 p
->prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
3703 p
->prio
= p
->static_prio
;
3707 * sched_setscheduler - change the scheduling policy and/or RT priority of
3709 * @p: the task in question.
3710 * @policy: new policy.
3711 * @param: structure containing the new RT priority.
3713 int sched_setscheduler(struct task_struct
*p
, int policy
,
3714 struct sched_param
*param
)
3717 int oldprio
, oldpolicy
= -1;
3718 prio_array_t
*array
;
3719 unsigned long flags
;
3723 /* double check policy once rq lock held */
3725 policy
= oldpolicy
= p
->policy
;
3726 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3727 policy
!= SCHED_NORMAL
)
3730 * Valid priorities for SCHED_FIFO and SCHED_RR are
3731 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3733 if (param
->sched_priority
< 0 ||
3734 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3735 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3737 if ((policy
== SCHED_NORMAL
) != (param
->sched_priority
== 0))
3741 * Allow unprivileged RT tasks to decrease priority:
3743 if (!capable(CAP_SYS_NICE
)) {
3744 /* can't change policy */
3745 if (policy
!= p
->policy
&&
3746 !p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3748 /* can't increase priority */
3749 if (policy
!= SCHED_NORMAL
&&
3750 param
->sched_priority
> p
->rt_priority
&&
3751 param
->sched_priority
>
3752 p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3754 /* can't change other user's priorities */
3755 if ((current
->euid
!= p
->euid
) &&
3756 (current
->euid
!= p
->uid
))
3760 retval
= security_task_setscheduler(p
, policy
, param
);
3764 * To be able to change p->policy safely, the apropriate
3765 * runqueue lock must be held.
3767 rq
= task_rq_lock(p
, &flags
);
3768 /* recheck policy now with rq lock held */
3769 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3770 policy
= oldpolicy
= -1;
3771 task_rq_unlock(rq
, &flags
);
3776 deactivate_task(p
, rq
);
3778 __setscheduler(p
, policy
, param
->sched_priority
);
3780 __activate_task(p
, rq
);
3782 * Reschedule if we are currently running on this runqueue and
3783 * our priority decreased, or if we are not currently running on
3784 * this runqueue and our priority is higher than the current's
3786 if (task_running(rq
, p
)) {
3787 if (p
->prio
> oldprio
)
3788 resched_task(rq
->curr
);
3789 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3790 resched_task(rq
->curr
);
3792 task_rq_unlock(rq
, &flags
);
3795 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3798 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3801 struct sched_param lparam
;
3802 struct task_struct
*p
;
3804 if (!param
|| pid
< 0)
3806 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3808 read_lock_irq(&tasklist_lock
);
3809 p
= find_process_by_pid(pid
);
3811 read_unlock_irq(&tasklist_lock
);
3814 retval
= sched_setscheduler(p
, policy
, &lparam
);
3815 read_unlock_irq(&tasklist_lock
);
3820 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3821 * @pid: the pid in question.
3822 * @policy: new policy.
3823 * @param: structure containing the new RT priority.
3825 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3826 struct sched_param __user
*param
)
3828 return do_sched_setscheduler(pid
, policy
, param
);
3832 * sys_sched_setparam - set/change the RT priority of a thread
3833 * @pid: the pid in question.
3834 * @param: structure containing the new RT priority.
3836 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3838 return do_sched_setscheduler(pid
, -1, param
);
3842 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3843 * @pid: the pid in question.
3845 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3847 int retval
= -EINVAL
;
3854 read_lock(&tasklist_lock
);
3855 p
= find_process_by_pid(pid
);
3857 retval
= security_task_getscheduler(p
);
3861 read_unlock(&tasklist_lock
);
3868 * sys_sched_getscheduler - get the RT priority of a thread
3869 * @pid: the pid in question.
3870 * @param: structure containing the RT priority.
3872 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3874 struct sched_param lp
;
3875 int retval
= -EINVAL
;
3878 if (!param
|| pid
< 0)
3881 read_lock(&tasklist_lock
);
3882 p
= find_process_by_pid(pid
);
3887 retval
= security_task_getscheduler(p
);
3891 lp
.sched_priority
= p
->rt_priority
;
3892 read_unlock(&tasklist_lock
);
3895 * This one might sleep, we cannot do it with a spinlock held ...
3897 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3903 read_unlock(&tasklist_lock
);
3907 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3911 cpumask_t cpus_allowed
;
3914 read_lock(&tasklist_lock
);
3916 p
= find_process_by_pid(pid
);
3918 read_unlock(&tasklist_lock
);
3919 unlock_cpu_hotplug();
3924 * It is not safe to call set_cpus_allowed with the
3925 * tasklist_lock held. We will bump the task_struct's
3926 * usage count and then drop tasklist_lock.
3929 read_unlock(&tasklist_lock
);
3932 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3933 !capable(CAP_SYS_NICE
))
3936 cpus_allowed
= cpuset_cpus_allowed(p
);
3937 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3938 retval
= set_cpus_allowed(p
, new_mask
);
3942 unlock_cpu_hotplug();
3946 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3947 cpumask_t
*new_mask
)
3949 if (len
< sizeof(cpumask_t
)) {
3950 memset(new_mask
, 0, sizeof(cpumask_t
));
3951 } else if (len
> sizeof(cpumask_t
)) {
3952 len
= sizeof(cpumask_t
);
3954 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3958 * sys_sched_setaffinity - set the cpu affinity of a process
3959 * @pid: pid of the process
3960 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3961 * @user_mask_ptr: user-space pointer to the new cpu mask
3963 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3964 unsigned long __user
*user_mask_ptr
)
3969 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3973 return sched_setaffinity(pid
, new_mask
);
3977 * Represents all cpu's present in the system
3978 * In systems capable of hotplug, this map could dynamically grow
3979 * as new cpu's are detected in the system via any platform specific
3980 * method, such as ACPI for e.g.
3983 cpumask_t cpu_present_map __read_mostly
;
3984 EXPORT_SYMBOL(cpu_present_map
);
3987 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
3988 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
3991 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
3997 read_lock(&tasklist_lock
);
4000 p
= find_process_by_pid(pid
);
4005 cpus_and(*mask
, p
->cpus_allowed
, cpu_possible_map
);
4008 read_unlock(&tasklist_lock
);
4009 unlock_cpu_hotplug();
4017 * sys_sched_getaffinity - get the cpu affinity of a process
4018 * @pid: pid of the process
4019 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4020 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4022 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4023 unsigned long __user
*user_mask_ptr
)
4028 if (len
< sizeof(cpumask_t
))
4031 ret
= sched_getaffinity(pid
, &mask
);
4035 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4038 return sizeof(cpumask_t
);
4042 * sys_sched_yield - yield the current processor to other threads.
4044 * this function yields the current CPU by moving the calling thread
4045 * to the expired array. If there are no other threads running on this
4046 * CPU then this function will return.
4048 asmlinkage
long sys_sched_yield(void)
4050 runqueue_t
*rq
= this_rq_lock();
4051 prio_array_t
*array
= current
->array
;
4052 prio_array_t
*target
= rq
->expired
;
4054 schedstat_inc(rq
, yld_cnt
);
4056 * We implement yielding by moving the task into the expired
4059 * (special rule: RT tasks will just roundrobin in the active
4062 if (rt_task(current
))
4063 target
= rq
->active
;
4065 if (array
->nr_active
== 1) {
4066 schedstat_inc(rq
, yld_act_empty
);
4067 if (!rq
->expired
->nr_active
)
4068 schedstat_inc(rq
, yld_both_empty
);
4069 } else if (!rq
->expired
->nr_active
)
4070 schedstat_inc(rq
, yld_exp_empty
);
4072 if (array
!= target
) {
4073 dequeue_task(current
, array
);
4074 enqueue_task(current
, target
);
4077 * requeue_task is cheaper so perform that if possible.
4079 requeue_task(current
, array
);
4082 * Since we are going to call schedule() anyway, there's
4083 * no need to preempt or enable interrupts:
4085 __release(rq
->lock
);
4086 _raw_spin_unlock(&rq
->lock
);
4087 preempt_enable_no_resched();
4094 static inline void __cond_resched(void)
4097 * The BKS might be reacquired before we have dropped
4098 * PREEMPT_ACTIVE, which could trigger a second
4099 * cond_resched() call.
4101 if (unlikely(preempt_count()))
4104 add_preempt_count(PREEMPT_ACTIVE
);
4106 sub_preempt_count(PREEMPT_ACTIVE
);
4107 } while (need_resched());
4110 int __sched
cond_resched(void)
4112 if (need_resched()) {
4119 EXPORT_SYMBOL(cond_resched
);
4122 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4123 * call schedule, and on return reacquire the lock.
4125 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4126 * operations here to prevent schedule() from being called twice (once via
4127 * spin_unlock(), once by hand).
4129 int cond_resched_lock(spinlock_t
*lock
)
4133 if (need_lockbreak(lock
)) {
4139 if (need_resched()) {
4140 _raw_spin_unlock(lock
);
4141 preempt_enable_no_resched();
4149 EXPORT_SYMBOL(cond_resched_lock
);
4151 int __sched
cond_resched_softirq(void)
4153 BUG_ON(!in_softirq());
4155 if (need_resched()) {
4156 __local_bh_enable();
4164 EXPORT_SYMBOL(cond_resched_softirq
);
4168 * yield - yield the current processor to other threads.
4170 * this is a shortcut for kernel-space yielding - it marks the
4171 * thread runnable and calls sys_sched_yield().
4173 void __sched
yield(void)
4175 set_current_state(TASK_RUNNING
);
4179 EXPORT_SYMBOL(yield
);
4182 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4183 * that process accounting knows that this is a task in IO wait state.
4185 * But don't do that if it is a deliberate, throttling IO wait (this task
4186 * has set its backing_dev_info: the queue against which it should throttle)
4188 void __sched
io_schedule(void)
4190 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4192 atomic_inc(&rq
->nr_iowait
);
4194 atomic_dec(&rq
->nr_iowait
);
4197 EXPORT_SYMBOL(io_schedule
);
4199 long __sched
io_schedule_timeout(long timeout
)
4201 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4204 atomic_inc(&rq
->nr_iowait
);
4205 ret
= schedule_timeout(timeout
);
4206 atomic_dec(&rq
->nr_iowait
);
4211 * sys_sched_get_priority_max - return maximum RT priority.
4212 * @policy: scheduling class.
4214 * this syscall returns the maximum rt_priority that can be used
4215 * by a given scheduling class.
4217 asmlinkage
long sys_sched_get_priority_max(int policy
)
4224 ret
= MAX_USER_RT_PRIO
-1;
4234 * sys_sched_get_priority_min - return minimum RT priority.
4235 * @policy: scheduling class.
4237 * this syscall returns the minimum rt_priority that can be used
4238 * by a given scheduling class.
4240 asmlinkage
long sys_sched_get_priority_min(int policy
)
4256 * sys_sched_rr_get_interval - return the default timeslice of a process.
4257 * @pid: pid of the process.
4258 * @interval: userspace pointer to the timeslice value.
4260 * this syscall writes the default timeslice value of a given process
4261 * into the user-space timespec buffer. A value of '0' means infinity.
4264 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4266 int retval
= -EINVAL
;
4274 read_lock(&tasklist_lock
);
4275 p
= find_process_by_pid(pid
);
4279 retval
= security_task_getscheduler(p
);
4283 jiffies_to_timespec(p
->policy
& SCHED_FIFO
?
4284 0 : task_timeslice(p
), &t
);
4285 read_unlock(&tasklist_lock
);
4286 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4290 read_unlock(&tasklist_lock
);
4294 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4296 if (list_empty(&p
->children
)) return NULL
;
4297 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4300 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4302 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
4303 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4306 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4308 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
4309 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4312 static void show_task(task_t
*p
)
4316 unsigned long free
= 0;
4317 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
4319 printk("%-13.13s ", p
->comm
);
4320 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4321 if (state
< ARRAY_SIZE(stat_nam
))
4322 printk(stat_nam
[state
]);
4325 #if (BITS_PER_LONG == 32)
4326 if (state
== TASK_RUNNING
)
4327 printk(" running ");
4329 printk(" %08lX ", thread_saved_pc(p
));
4331 if (state
== TASK_RUNNING
)
4332 printk(" running task ");
4334 printk(" %016lx ", thread_saved_pc(p
));
4336 #ifdef CONFIG_DEBUG_STACK_USAGE
4338 unsigned long *n
= end_of_stack(p
);
4341 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4344 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4345 if ((relative
= eldest_child(p
)))
4346 printk("%5d ", relative
->pid
);
4349 if ((relative
= younger_sibling(p
)))
4350 printk("%7d", relative
->pid
);
4353 if ((relative
= older_sibling(p
)))
4354 printk(" %5d", relative
->pid
);
4358 printk(" (L-TLB)\n");
4360 printk(" (NOTLB)\n");
4362 if (state
!= TASK_RUNNING
)
4363 show_stack(p
, NULL
);
4366 void show_state(void)
4370 #if (BITS_PER_LONG == 32)
4373 printk(" task PC pid father child younger older\n");
4377 printk(" task PC pid father child younger older\n");
4379 read_lock(&tasklist_lock
);
4380 do_each_thread(g
, p
) {
4382 * reset the NMI-timeout, listing all files on a slow
4383 * console might take alot of time:
4385 touch_nmi_watchdog();
4387 } while_each_thread(g
, p
);
4389 read_unlock(&tasklist_lock
);
4390 mutex_debug_show_all_locks();
4394 * init_idle - set up an idle thread for a given CPU
4395 * @idle: task in question
4396 * @cpu: cpu the idle task belongs to
4398 * NOTE: this function does not set the idle thread's NEED_RESCHED
4399 * flag, to make booting more robust.
4401 void __devinit
init_idle(task_t
*idle
, int cpu
)
4403 runqueue_t
*rq
= cpu_rq(cpu
);
4404 unsigned long flags
;
4406 idle
->sleep_avg
= 0;
4408 idle
->prio
= MAX_PRIO
;
4409 idle
->state
= TASK_RUNNING
;
4410 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4411 set_task_cpu(idle
, cpu
);
4413 spin_lock_irqsave(&rq
->lock
, flags
);
4414 rq
->curr
= rq
->idle
= idle
;
4415 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4418 spin_unlock_irqrestore(&rq
->lock
, flags
);
4420 /* Set the preempt count _outside_ the spinlocks! */
4421 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4422 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4424 task_thread_info(idle
)->preempt_count
= 0;
4429 * In a system that switches off the HZ timer nohz_cpu_mask
4430 * indicates which cpus entered this state. This is used
4431 * in the rcu update to wait only for active cpus. For system
4432 * which do not switch off the HZ timer nohz_cpu_mask should
4433 * always be CPU_MASK_NONE.
4435 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4439 * This is how migration works:
4441 * 1) we queue a migration_req_t structure in the source CPU's
4442 * runqueue and wake up that CPU's migration thread.
4443 * 2) we down() the locked semaphore => thread blocks.
4444 * 3) migration thread wakes up (implicitly it forces the migrated
4445 * thread off the CPU)
4446 * 4) it gets the migration request and checks whether the migrated
4447 * task is still in the wrong runqueue.
4448 * 5) if it's in the wrong runqueue then the migration thread removes
4449 * it and puts it into the right queue.
4450 * 6) migration thread up()s the semaphore.
4451 * 7) we wake up and the migration is done.
4455 * Change a given task's CPU affinity. Migrate the thread to a
4456 * proper CPU and schedule it away if the CPU it's executing on
4457 * is removed from the allowed bitmask.
4459 * NOTE: the caller must have a valid reference to the task, the
4460 * task must not exit() & deallocate itself prematurely. The
4461 * call is not atomic; no spinlocks may be held.
4463 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4465 unsigned long flags
;
4467 migration_req_t req
;
4470 rq
= task_rq_lock(p
, &flags
);
4471 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4476 p
->cpus_allowed
= new_mask
;
4477 /* Can the task run on the task's current CPU? If so, we're done */
4478 if (cpu_isset(task_cpu(p
), new_mask
))
4481 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4482 /* Need help from migration thread: drop lock and wait. */
4483 task_rq_unlock(rq
, &flags
);
4484 wake_up_process(rq
->migration_thread
);
4485 wait_for_completion(&req
.done
);
4486 tlb_migrate_finish(p
->mm
);
4490 task_rq_unlock(rq
, &flags
);
4494 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4497 * Move (not current) task off this cpu, onto dest cpu. We're doing
4498 * this because either it can't run here any more (set_cpus_allowed()
4499 * away from this CPU, or CPU going down), or because we're
4500 * attempting to rebalance this task on exec (sched_exec).
4502 * So we race with normal scheduler movements, but that's OK, as long
4503 * as the task is no longer on this CPU.
4505 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4507 runqueue_t
*rq_dest
, *rq_src
;
4509 if (unlikely(cpu_is_offline(dest_cpu
)))
4512 rq_src
= cpu_rq(src_cpu
);
4513 rq_dest
= cpu_rq(dest_cpu
);
4515 double_rq_lock(rq_src
, rq_dest
);
4516 /* Already moved. */
4517 if (task_cpu(p
) != src_cpu
)
4519 /* Affinity changed (again). */
4520 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4523 set_task_cpu(p
, dest_cpu
);
4526 * Sync timestamp with rq_dest's before activating.
4527 * The same thing could be achieved by doing this step
4528 * afterwards, and pretending it was a local activate.
4529 * This way is cleaner and logically correct.
4531 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4532 + rq_dest
->timestamp_last_tick
;
4533 deactivate_task(p
, rq_src
);
4534 activate_task(p
, rq_dest
, 0);
4535 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4536 resched_task(rq_dest
->curr
);
4540 double_rq_unlock(rq_src
, rq_dest
);
4544 * migration_thread - this is a highprio system thread that performs
4545 * thread migration by bumping thread off CPU then 'pushing' onto
4548 static int migration_thread(void *data
)
4551 int cpu
= (long)data
;
4554 BUG_ON(rq
->migration_thread
!= current
);
4556 set_current_state(TASK_INTERRUPTIBLE
);
4557 while (!kthread_should_stop()) {
4558 struct list_head
*head
;
4559 migration_req_t
*req
;
4563 spin_lock_irq(&rq
->lock
);
4565 if (cpu_is_offline(cpu
)) {
4566 spin_unlock_irq(&rq
->lock
);
4570 if (rq
->active_balance
) {
4571 active_load_balance(rq
, cpu
);
4572 rq
->active_balance
= 0;
4575 head
= &rq
->migration_queue
;
4577 if (list_empty(head
)) {
4578 spin_unlock_irq(&rq
->lock
);
4580 set_current_state(TASK_INTERRUPTIBLE
);
4583 req
= list_entry(head
->next
, migration_req_t
, list
);
4584 list_del_init(head
->next
);
4586 spin_unlock(&rq
->lock
);
4587 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4590 complete(&req
->done
);
4592 __set_current_state(TASK_RUNNING
);
4596 /* Wait for kthread_stop */
4597 set_current_state(TASK_INTERRUPTIBLE
);
4598 while (!kthread_should_stop()) {
4600 set_current_state(TASK_INTERRUPTIBLE
);
4602 __set_current_state(TASK_RUNNING
);
4606 #ifdef CONFIG_HOTPLUG_CPU
4607 /* Figure out where task on dead CPU should go, use force if neccessary. */
4608 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4614 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4615 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4616 dest_cpu
= any_online_cpu(mask
);
4618 /* On any allowed CPU? */
4619 if (dest_cpu
== NR_CPUS
)
4620 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4622 /* No more Mr. Nice Guy. */
4623 if (dest_cpu
== NR_CPUS
) {
4624 cpus_setall(tsk
->cpus_allowed
);
4625 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4628 * Don't tell them about moving exiting tasks or
4629 * kernel threads (both mm NULL), since they never
4632 if (tsk
->mm
&& printk_ratelimit())
4633 printk(KERN_INFO
"process %d (%s) no "
4634 "longer affine to cpu%d\n",
4635 tsk
->pid
, tsk
->comm
, dead_cpu
);
4637 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4641 * While a dead CPU has no uninterruptible tasks queued at this point,
4642 * it might still have a nonzero ->nr_uninterruptible counter, because
4643 * for performance reasons the counter is not stricly tracking tasks to
4644 * their home CPUs. So we just add the counter to another CPU's counter,
4645 * to keep the global sum constant after CPU-down:
4647 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4649 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4650 unsigned long flags
;
4652 local_irq_save(flags
);
4653 double_rq_lock(rq_src
, rq_dest
);
4654 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4655 rq_src
->nr_uninterruptible
= 0;
4656 double_rq_unlock(rq_src
, rq_dest
);
4657 local_irq_restore(flags
);
4660 /* Run through task list and migrate tasks from the dead cpu. */
4661 static void migrate_live_tasks(int src_cpu
)
4663 struct task_struct
*tsk
, *t
;
4665 write_lock_irq(&tasklist_lock
);
4667 do_each_thread(t
, tsk
) {
4671 if (task_cpu(tsk
) == src_cpu
)
4672 move_task_off_dead_cpu(src_cpu
, tsk
);
4673 } while_each_thread(t
, tsk
);
4675 write_unlock_irq(&tasklist_lock
);
4678 /* Schedules idle task to be the next runnable task on current CPU.
4679 * It does so by boosting its priority to highest possible and adding it to
4680 * the _front_ of runqueue. Used by CPU offline code.
4682 void sched_idle_next(void)
4684 int cpu
= smp_processor_id();
4685 runqueue_t
*rq
= this_rq();
4686 struct task_struct
*p
= rq
->idle
;
4687 unsigned long flags
;
4689 /* cpu has to be offline */
4690 BUG_ON(cpu_online(cpu
));
4692 /* Strictly not necessary since rest of the CPUs are stopped by now
4693 * and interrupts disabled on current cpu.
4695 spin_lock_irqsave(&rq
->lock
, flags
);
4697 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4698 /* Add idle task to _front_ of it's priority queue */
4699 __activate_idle_task(p
, rq
);
4701 spin_unlock_irqrestore(&rq
->lock
, flags
);
4704 /* Ensures that the idle task is using init_mm right before its cpu goes
4707 void idle_task_exit(void)
4709 struct mm_struct
*mm
= current
->active_mm
;
4711 BUG_ON(cpu_online(smp_processor_id()));
4714 switch_mm(mm
, &init_mm
, current
);
4718 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4720 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4722 /* Must be exiting, otherwise would be on tasklist. */
4723 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4725 /* Cannot have done final schedule yet: would have vanished. */
4726 BUG_ON(tsk
->flags
& PF_DEAD
);
4728 get_task_struct(tsk
);
4731 * Drop lock around migration; if someone else moves it,
4732 * that's OK. No task can be added to this CPU, so iteration is
4735 spin_unlock_irq(&rq
->lock
);
4736 move_task_off_dead_cpu(dead_cpu
, tsk
);
4737 spin_lock_irq(&rq
->lock
);
4739 put_task_struct(tsk
);
4742 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4743 static void migrate_dead_tasks(unsigned int dead_cpu
)
4746 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4748 for (arr
= 0; arr
< 2; arr
++) {
4749 for (i
= 0; i
< MAX_PRIO
; i
++) {
4750 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4751 while (!list_empty(list
))
4752 migrate_dead(dead_cpu
,
4753 list_entry(list
->next
, task_t
,
4758 #endif /* CONFIG_HOTPLUG_CPU */
4761 * migration_call - callback that gets triggered when a CPU is added.
4762 * Here we can start up the necessary migration thread for the new CPU.
4764 static int migration_call(struct notifier_block
*nfb
, unsigned long action
,
4767 int cpu
= (long)hcpu
;
4768 struct task_struct
*p
;
4769 struct runqueue
*rq
;
4770 unsigned long flags
;
4773 case CPU_UP_PREPARE
:
4774 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4777 p
->flags
|= PF_NOFREEZE
;
4778 kthread_bind(p
, cpu
);
4779 /* Must be high prio: stop_machine expects to yield to it. */
4780 rq
= task_rq_lock(p
, &flags
);
4781 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4782 task_rq_unlock(rq
, &flags
);
4783 cpu_rq(cpu
)->migration_thread
= p
;
4786 /* Strictly unneccessary, as first user will wake it. */
4787 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4789 #ifdef CONFIG_HOTPLUG_CPU
4790 case CPU_UP_CANCELED
:
4791 /* Unbind it from offline cpu so it can run. Fall thru. */
4792 kthread_bind(cpu_rq(cpu
)->migration_thread
,
4793 any_online_cpu(cpu_online_map
));
4794 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4795 cpu_rq(cpu
)->migration_thread
= NULL
;
4798 migrate_live_tasks(cpu
);
4800 kthread_stop(rq
->migration_thread
);
4801 rq
->migration_thread
= NULL
;
4802 /* Idle task back to normal (off runqueue, low prio) */
4803 rq
= task_rq_lock(rq
->idle
, &flags
);
4804 deactivate_task(rq
->idle
, rq
);
4805 rq
->idle
->static_prio
= MAX_PRIO
;
4806 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4807 migrate_dead_tasks(cpu
);
4808 task_rq_unlock(rq
, &flags
);
4809 migrate_nr_uninterruptible(rq
);
4810 BUG_ON(rq
->nr_running
!= 0);
4812 /* No need to migrate the tasks: it was best-effort if
4813 * they didn't do lock_cpu_hotplug(). Just wake up
4814 * the requestors. */
4815 spin_lock_irq(&rq
->lock
);
4816 while (!list_empty(&rq
->migration_queue
)) {
4817 migration_req_t
*req
;
4818 req
= list_entry(rq
->migration_queue
.next
,
4819 migration_req_t
, list
);
4820 list_del_init(&req
->list
);
4821 complete(&req
->done
);
4823 spin_unlock_irq(&rq
->lock
);
4830 /* Register at highest priority so that task migration (migrate_all_tasks)
4831 * happens before everything else.
4833 static struct notifier_block __devinitdata migration_notifier
= {
4834 .notifier_call
= migration_call
,
4838 int __init
migration_init(void)
4840 void *cpu
= (void *)(long)smp_processor_id();
4841 /* Start one for boot CPU. */
4842 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4843 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4844 register_cpu_notifier(&migration_notifier
);
4850 #undef SCHED_DOMAIN_DEBUG
4851 #ifdef SCHED_DOMAIN_DEBUG
4852 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4857 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4861 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4866 struct sched_group
*group
= sd
->groups
;
4867 cpumask_t groupmask
;
4869 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4870 cpus_clear(groupmask
);
4873 for (i
= 0; i
< level
+ 1; i
++)
4875 printk("domain %d: ", level
);
4877 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4878 printk("does not load-balance\n");
4880 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4884 printk("span %s\n", str
);
4886 if (!cpu_isset(cpu
, sd
->span
))
4887 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4888 if (!cpu_isset(cpu
, group
->cpumask
))
4889 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4892 for (i
= 0; i
< level
+ 2; i
++)
4898 printk(KERN_ERR
"ERROR: group is NULL\n");
4902 if (!group
->cpu_power
) {
4904 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4907 if (!cpus_weight(group
->cpumask
)) {
4909 printk(KERN_ERR
"ERROR: empty group\n");
4912 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4914 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4917 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4919 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4922 group
= group
->next
;
4923 } while (group
!= sd
->groups
);
4926 if (!cpus_equal(sd
->span
, groupmask
))
4927 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4933 if (!cpus_subset(groupmask
, sd
->span
))
4934 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4940 #define sched_domain_debug(sd, cpu) {}
4943 static int sd_degenerate(struct sched_domain
*sd
)
4945 if (cpus_weight(sd
->span
) == 1)
4948 /* Following flags need at least 2 groups */
4949 if (sd
->flags
& (SD_LOAD_BALANCE
|
4950 SD_BALANCE_NEWIDLE
|
4953 if (sd
->groups
!= sd
->groups
->next
)
4957 /* Following flags don't use groups */
4958 if (sd
->flags
& (SD_WAKE_IDLE
|
4966 static int sd_parent_degenerate(struct sched_domain
*sd
,
4967 struct sched_domain
*parent
)
4969 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
4971 if (sd_degenerate(parent
))
4974 if (!cpus_equal(sd
->span
, parent
->span
))
4977 /* Does parent contain flags not in child? */
4978 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
4979 if (cflags
& SD_WAKE_AFFINE
)
4980 pflags
&= ~SD_WAKE_BALANCE
;
4981 /* Flags needing groups don't count if only 1 group in parent */
4982 if (parent
->groups
== parent
->groups
->next
) {
4983 pflags
&= ~(SD_LOAD_BALANCE
|
4984 SD_BALANCE_NEWIDLE
|
4988 if (~cflags
& pflags
)
4995 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4996 * hold the hotplug lock.
4998 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5000 runqueue_t
*rq
= cpu_rq(cpu
);
5001 struct sched_domain
*tmp
;
5003 /* Remove the sched domains which do not contribute to scheduling. */
5004 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5005 struct sched_domain
*parent
= tmp
->parent
;
5008 if (sd_parent_degenerate(tmp
, parent
))
5009 tmp
->parent
= parent
->parent
;
5012 if (sd
&& sd_degenerate(sd
))
5015 sched_domain_debug(sd
, cpu
);
5017 rcu_assign_pointer(rq
->sd
, sd
);
5020 /* cpus with isolated domains */
5021 static cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
5023 /* Setup the mask of cpus configured for isolated domains */
5024 static int __init
isolated_cpu_setup(char *str
)
5026 int ints
[NR_CPUS
], i
;
5028 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5029 cpus_clear(cpu_isolated_map
);
5030 for (i
= 1; i
<= ints
[0]; i
++)
5031 if (ints
[i
] < NR_CPUS
)
5032 cpu_set(ints
[i
], cpu_isolated_map
);
5036 __setup ("isolcpus=", isolated_cpu_setup
);
5039 * init_sched_build_groups takes an array of groups, the cpumask we wish
5040 * to span, and a pointer to a function which identifies what group a CPU
5041 * belongs to. The return value of group_fn must be a valid index into the
5042 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
5043 * keep track of groups covered with a cpumask_t).
5045 * init_sched_build_groups will build a circular linked list of the groups
5046 * covered by the given span, and will set each group's ->cpumask correctly,
5047 * and ->cpu_power to 0.
5049 static void init_sched_build_groups(struct sched_group groups
[], cpumask_t span
,
5050 int (*group_fn
)(int cpu
))
5052 struct sched_group
*first
= NULL
, *last
= NULL
;
5053 cpumask_t covered
= CPU_MASK_NONE
;
5056 for_each_cpu_mask(i
, span
) {
5057 int group
= group_fn(i
);
5058 struct sched_group
*sg
= &groups
[group
];
5061 if (cpu_isset(i
, covered
))
5064 sg
->cpumask
= CPU_MASK_NONE
;
5067 for_each_cpu_mask(j
, span
) {
5068 if (group_fn(j
) != group
)
5071 cpu_set(j
, covered
);
5072 cpu_set(j
, sg
->cpumask
);
5083 #define SD_NODES_PER_DOMAIN 16
5087 * find_next_best_node - find the next node to include in a sched_domain
5088 * @node: node whose sched_domain we're building
5089 * @used_nodes: nodes already in the sched_domain
5091 * Find the next node to include in a given scheduling domain. Simply
5092 * finds the closest node not already in the @used_nodes map.
5094 * Should use nodemask_t.
5096 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5098 int i
, n
, val
, min_val
, best_node
= 0;
5102 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5103 /* Start at @node */
5104 n
= (node
+ i
) % MAX_NUMNODES
;
5106 if (!nr_cpus_node(n
))
5109 /* Skip already used nodes */
5110 if (test_bit(n
, used_nodes
))
5113 /* Simple min distance search */
5114 val
= node_distance(node
, n
);
5116 if (val
< min_val
) {
5122 set_bit(best_node
, used_nodes
);
5127 * sched_domain_node_span - get a cpumask for a node's sched_domain
5128 * @node: node whose cpumask we're constructing
5129 * @size: number of nodes to include in this span
5131 * Given a node, construct a good cpumask for its sched_domain to span. It
5132 * should be one that prevents unnecessary balancing, but also spreads tasks
5135 static cpumask_t
sched_domain_node_span(int node
)
5138 cpumask_t span
, nodemask
;
5139 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5142 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5144 nodemask
= node_to_cpumask(node
);
5145 cpus_or(span
, span
, nodemask
);
5146 set_bit(node
, used_nodes
);
5148 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5149 int next_node
= find_next_best_node(node
, used_nodes
);
5150 nodemask
= node_to_cpumask(next_node
);
5151 cpus_or(span
, span
, nodemask
);
5159 * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
5160 * can switch it on easily if needed.
5162 #ifdef CONFIG_SCHED_SMT
5163 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5164 static struct sched_group sched_group_cpus
[NR_CPUS
];
5165 static int cpu_to_cpu_group(int cpu
)
5171 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5172 static struct sched_group sched_group_phys
[NR_CPUS
];
5173 static int cpu_to_phys_group(int cpu
)
5175 #ifdef CONFIG_SCHED_SMT
5176 return first_cpu(cpu_sibling_map
[cpu
]);
5184 * The init_sched_build_groups can't handle what we want to do with node
5185 * groups, so roll our own. Now each node has its own list of groups which
5186 * gets dynamically allocated.
5188 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5189 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5191 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5192 static struct sched_group
*sched_group_allnodes_bycpu
[NR_CPUS
];
5194 static int cpu_to_allnodes_group(int cpu
)
5196 return cpu_to_node(cpu
);
5201 * Build sched domains for a given set of cpus and attach the sched domains
5202 * to the individual cpus
5204 void build_sched_domains(const cpumask_t
*cpu_map
)
5208 struct sched_group
**sched_group_nodes
= NULL
;
5209 struct sched_group
*sched_group_allnodes
= NULL
;
5212 * Allocate the per-node list of sched groups
5214 sched_group_nodes
= kmalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
5216 if (!sched_group_nodes
) {
5217 printk(KERN_WARNING
"Can not alloc sched group node list\n");
5220 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
5224 * Set up domains for cpus specified by the cpu_map.
5226 for_each_cpu_mask(i
, *cpu_map
) {
5228 struct sched_domain
*sd
= NULL
, *p
;
5229 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
5231 cpus_and(nodemask
, nodemask
, *cpu_map
);
5234 if (cpus_weight(*cpu_map
)
5235 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
5236 if (!sched_group_allnodes
) {
5237 sched_group_allnodes
5238 = kmalloc(sizeof(struct sched_group
)
5241 if (!sched_group_allnodes
) {
5243 "Can not alloc allnodes sched group\n");
5246 sched_group_allnodes_bycpu
[i
]
5247 = sched_group_allnodes
;
5249 sd
= &per_cpu(allnodes_domains
, i
);
5250 *sd
= SD_ALLNODES_INIT
;
5251 sd
->span
= *cpu_map
;
5252 group
= cpu_to_allnodes_group(i
);
5253 sd
->groups
= &sched_group_allnodes
[group
];
5258 sd
= &per_cpu(node_domains
, i
);
5260 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
5262 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5266 sd
= &per_cpu(phys_domains
, i
);
5267 group
= cpu_to_phys_group(i
);
5269 sd
->span
= nodemask
;
5271 sd
->groups
= &sched_group_phys
[group
];
5273 #ifdef CONFIG_SCHED_SMT
5275 sd
= &per_cpu(cpu_domains
, i
);
5276 group
= cpu_to_cpu_group(i
);
5277 *sd
= SD_SIBLING_INIT
;
5278 sd
->span
= cpu_sibling_map
[i
];
5279 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5281 sd
->groups
= &sched_group_cpus
[group
];
5285 #ifdef CONFIG_SCHED_SMT
5286 /* Set up CPU (sibling) groups */
5287 for_each_cpu_mask(i
, *cpu_map
) {
5288 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
5289 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
5290 if (i
!= first_cpu(this_sibling_map
))
5293 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
5298 /* Set up physical groups */
5299 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5300 cpumask_t nodemask
= node_to_cpumask(i
);
5302 cpus_and(nodemask
, nodemask
, *cpu_map
);
5303 if (cpus_empty(nodemask
))
5306 init_sched_build_groups(sched_group_phys
, nodemask
,
5307 &cpu_to_phys_group
);
5311 /* Set up node groups */
5312 if (sched_group_allnodes
)
5313 init_sched_build_groups(sched_group_allnodes
, *cpu_map
,
5314 &cpu_to_allnodes_group
);
5316 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5317 /* Set up node groups */
5318 struct sched_group
*sg
, *prev
;
5319 cpumask_t nodemask
= node_to_cpumask(i
);
5320 cpumask_t domainspan
;
5321 cpumask_t covered
= CPU_MASK_NONE
;
5324 cpus_and(nodemask
, nodemask
, *cpu_map
);
5325 if (cpus_empty(nodemask
)) {
5326 sched_group_nodes
[i
] = NULL
;
5330 domainspan
= sched_domain_node_span(i
);
5331 cpus_and(domainspan
, domainspan
, *cpu_map
);
5333 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5334 sched_group_nodes
[i
] = sg
;
5335 for_each_cpu_mask(j
, nodemask
) {
5336 struct sched_domain
*sd
;
5337 sd
= &per_cpu(node_domains
, j
);
5339 if (sd
->groups
== NULL
) {
5340 /* Turn off balancing if we have no groups */
5346 "Can not alloc domain group for node %d\n", i
);
5350 sg
->cpumask
= nodemask
;
5351 cpus_or(covered
, covered
, nodemask
);
5354 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
5355 cpumask_t tmp
, notcovered
;
5356 int n
= (i
+ j
) % MAX_NUMNODES
;
5358 cpus_complement(notcovered
, covered
);
5359 cpus_and(tmp
, notcovered
, *cpu_map
);
5360 cpus_and(tmp
, tmp
, domainspan
);
5361 if (cpus_empty(tmp
))
5364 nodemask
= node_to_cpumask(n
);
5365 cpus_and(tmp
, tmp
, nodemask
);
5366 if (cpus_empty(tmp
))
5369 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5372 "Can not alloc domain group for node %d\n", j
);
5377 cpus_or(covered
, covered
, tmp
);
5381 prev
->next
= sched_group_nodes
[i
];
5385 /* Calculate CPU power for physical packages and nodes */
5386 for_each_cpu_mask(i
, *cpu_map
) {
5388 struct sched_domain
*sd
;
5389 #ifdef CONFIG_SCHED_SMT
5390 sd
= &per_cpu(cpu_domains
, i
);
5391 power
= SCHED_LOAD_SCALE
;
5392 sd
->groups
->cpu_power
= power
;
5395 sd
= &per_cpu(phys_domains
, i
);
5396 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5397 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5398 sd
->groups
->cpu_power
= power
;
5401 sd
= &per_cpu(allnodes_domains
, i
);
5403 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5404 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5405 sd
->groups
->cpu_power
= power
;
5411 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5412 struct sched_group
*sg
= sched_group_nodes
[i
];
5418 for_each_cpu_mask(j
, sg
->cpumask
) {
5419 struct sched_domain
*sd
;
5422 sd
= &per_cpu(phys_domains
, j
);
5423 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5425 * Only add "power" once for each
5430 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5431 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5433 sg
->cpu_power
+= power
;
5436 if (sg
!= sched_group_nodes
[i
])
5441 /* Attach the domains */
5442 for_each_cpu_mask(i
, *cpu_map
) {
5443 struct sched_domain
*sd
;
5444 #ifdef CONFIG_SCHED_SMT
5445 sd
= &per_cpu(cpu_domains
, i
);
5447 sd
= &per_cpu(phys_domains
, i
);
5449 cpu_attach_domain(sd
, i
);
5453 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5455 static void arch_init_sched_domains(const cpumask_t
*cpu_map
)
5457 cpumask_t cpu_default_map
;
5460 * Setup mask for cpus without special case scheduling requirements.
5461 * For now this just excludes isolated cpus, but could be used to
5462 * exclude other special cases in the future.
5464 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
5466 build_sched_domains(&cpu_default_map
);
5469 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
5475 for_each_cpu_mask(cpu
, *cpu_map
) {
5476 struct sched_group
*sched_group_allnodes
5477 = sched_group_allnodes_bycpu
[cpu
];
5478 struct sched_group
**sched_group_nodes
5479 = sched_group_nodes_bycpu
[cpu
];
5481 if (sched_group_allnodes
) {
5482 kfree(sched_group_allnodes
);
5483 sched_group_allnodes_bycpu
[cpu
] = NULL
;
5486 if (!sched_group_nodes
)
5489 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5490 cpumask_t nodemask
= node_to_cpumask(i
);
5491 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5493 cpus_and(nodemask
, nodemask
, *cpu_map
);
5494 if (cpus_empty(nodemask
))
5504 if (oldsg
!= sched_group_nodes
[i
])
5507 kfree(sched_group_nodes
);
5508 sched_group_nodes_bycpu
[cpu
] = NULL
;
5514 * Detach sched domains from a group of cpus specified in cpu_map
5515 * These cpus will now be attached to the NULL domain
5517 static inline void detach_destroy_domains(const cpumask_t
*cpu_map
)
5521 for_each_cpu_mask(i
, *cpu_map
)
5522 cpu_attach_domain(NULL
, i
);
5523 synchronize_sched();
5524 arch_destroy_sched_domains(cpu_map
);
5528 * Partition sched domains as specified by the cpumasks below.
5529 * This attaches all cpus from the cpumasks to the NULL domain,
5530 * waits for a RCU quiescent period, recalculates sched
5531 * domain information and then attaches them back to the
5532 * correct sched domains
5533 * Call with hotplug lock held
5535 void partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
5537 cpumask_t change_map
;
5539 cpus_and(*partition1
, *partition1
, cpu_online_map
);
5540 cpus_and(*partition2
, *partition2
, cpu_online_map
);
5541 cpus_or(change_map
, *partition1
, *partition2
);
5543 /* Detach sched domains from all of the affected cpus */
5544 detach_destroy_domains(&change_map
);
5545 if (!cpus_empty(*partition1
))
5546 build_sched_domains(partition1
);
5547 if (!cpus_empty(*partition2
))
5548 build_sched_domains(partition2
);
5551 #ifdef CONFIG_HOTPLUG_CPU
5553 * Force a reinitialization of the sched domains hierarchy. The domains
5554 * and groups cannot be updated in place without racing with the balancing
5555 * code, so we temporarily attach all running cpus to the NULL domain
5556 * which will prevent rebalancing while the sched domains are recalculated.
5558 static int update_sched_domains(struct notifier_block
*nfb
,
5559 unsigned long action
, void *hcpu
)
5562 case CPU_UP_PREPARE
:
5563 case CPU_DOWN_PREPARE
:
5564 detach_destroy_domains(&cpu_online_map
);
5567 case CPU_UP_CANCELED
:
5568 case CPU_DOWN_FAILED
:
5572 * Fall through and re-initialise the domains.
5579 /* The hotplug lock is already held by cpu_up/cpu_down */
5580 arch_init_sched_domains(&cpu_online_map
);
5586 void __init
sched_init_smp(void)
5589 arch_init_sched_domains(&cpu_online_map
);
5590 unlock_cpu_hotplug();
5591 /* XXX: Theoretical race here - CPU may be hotplugged now */
5592 hotcpu_notifier(update_sched_domains
, 0);
5595 void __init
sched_init_smp(void)
5598 #endif /* CONFIG_SMP */
5600 int in_sched_functions(unsigned long addr
)
5602 /* Linker adds these: start and end of __sched functions */
5603 extern char __sched_text_start
[], __sched_text_end
[];
5604 return in_lock_functions(addr
) ||
5605 (addr
>= (unsigned long)__sched_text_start
5606 && addr
< (unsigned long)__sched_text_end
);
5609 void __init
sched_init(void)
5614 for (i
= 0; i
< NR_CPUS
; i
++) {
5615 prio_array_t
*array
;
5618 spin_lock_init(&rq
->lock
);
5620 rq
->active
= rq
->arrays
;
5621 rq
->expired
= rq
->arrays
+ 1;
5622 rq
->best_expired_prio
= MAX_PRIO
;
5626 for (j
= 1; j
< 3; j
++)
5627 rq
->cpu_load
[j
] = 0;
5628 rq
->active_balance
= 0;
5630 rq
->migration_thread
= NULL
;
5631 INIT_LIST_HEAD(&rq
->migration_queue
);
5633 atomic_set(&rq
->nr_iowait
, 0);
5635 for (j
= 0; j
< 2; j
++) {
5636 array
= rq
->arrays
+ j
;
5637 for (k
= 0; k
< MAX_PRIO
; k
++) {
5638 INIT_LIST_HEAD(array
->queue
+ k
);
5639 __clear_bit(k
, array
->bitmap
);
5641 // delimiter for bitsearch
5642 __set_bit(MAX_PRIO
, array
->bitmap
);
5647 * The boot idle thread does lazy MMU switching as well:
5649 atomic_inc(&init_mm
.mm_count
);
5650 enter_lazy_tlb(&init_mm
, current
);
5653 * Make us the idle thread. Technically, schedule() should not be
5654 * called from this thread, however somewhere below it might be,
5655 * but because we are the idle thread, we just pick up running again
5656 * when this runqueue becomes "idle".
5658 init_idle(current
, smp_processor_id());
5661 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
5662 void __might_sleep(char *file
, int line
)
5664 #if defined(in_atomic)
5665 static unsigned long prev_jiffy
; /* ratelimiting */
5667 if ((in_atomic() || irqs_disabled()) &&
5668 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
5669 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
5671 prev_jiffy
= jiffies
;
5672 printk(KERN_ERR
"Debug: sleeping function called from invalid"
5673 " context at %s:%d\n", file
, line
);
5674 printk("in_atomic():%d, irqs_disabled():%d\n",
5675 in_atomic(), irqs_disabled());
5680 EXPORT_SYMBOL(__might_sleep
);
5683 #ifdef CONFIG_MAGIC_SYSRQ
5684 void normalize_rt_tasks(void)
5686 struct task_struct
*p
;
5687 prio_array_t
*array
;
5688 unsigned long flags
;
5691 read_lock_irq(&tasklist_lock
);
5692 for_each_process (p
) {
5696 rq
= task_rq_lock(p
, &flags
);
5700 deactivate_task(p
, task_rq(p
));
5701 __setscheduler(p
, SCHED_NORMAL
, 0);
5703 __activate_task(p
, task_rq(p
));
5704 resched_task(rq
->curr
);
5707 task_rq_unlock(rq
, &flags
);
5709 read_unlock_irq(&tasklist_lock
);
5712 #endif /* CONFIG_MAGIC_SYSRQ */
5716 * These functions are only useful for the IA64 MCA handling.
5718 * They can only be called when the whole system has been
5719 * stopped - every CPU needs to be quiescent, and no scheduling
5720 * activity can take place. Using them for anything else would
5721 * be a serious bug, and as a result, they aren't even visible
5722 * under any other configuration.
5726 * curr_task - return the current task for a given cpu.
5727 * @cpu: the processor in question.
5729 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
5731 task_t
*curr_task(int cpu
)
5733 return cpu_curr(cpu
);
5737 * set_curr_task - set the current task for a given cpu.
5738 * @cpu: the processor in question.
5739 * @p: the task pointer to set.
5741 * Description: This function must only be used when non-maskable interrupts
5742 * are serviced on a separate stack. It allows the architecture to switch the
5743 * notion of the current task on a cpu in a non-blocking manner. This function
5744 * must be called with all CPU's synchronized, and interrupts disabled, the
5745 * and caller must save the original value of the current task (see
5746 * curr_task() above) and restore that value before reenabling interrupts and
5747 * re-starting the system.
5749 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
5751 void set_curr_task(int cpu
, task_t
*p
)