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/vmalloc.h>
38 #include <linux/blkdev.h>
39 #include <linux/delay.h>
40 #include <linux/smp.h>
41 #include <linux/threads.h>
42 #include <linux/timer.h>
43 #include <linux/rcupdate.h>
44 #include <linux/cpu.h>
45 #include <linux/cpuset.h>
46 #include <linux/percpu.h>
47 #include <linux/kthread.h>
48 #include <linux/seq_file.h>
49 #include <linux/syscalls.h>
50 #include <linux/times.h>
51 #include <linux/acct.h>
54 #include <asm/unistd.h>
57 * Convert user-nice values [ -20 ... 0 ... 19 ]
58 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
61 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
62 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
63 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
66 * 'User priority' is the nice value converted to something we
67 * can work with better when scaling various scheduler parameters,
68 * it's a [ 0 ... 39 ] range.
70 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
71 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
72 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
75 * Some helpers for converting nanosecond timing to jiffy resolution
77 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
78 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
81 * These are the 'tuning knobs' of the scheduler:
83 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
84 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
85 * Timeslices get refilled after they expire.
87 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
88 #define DEF_TIMESLICE (100 * HZ / 1000)
89 #define ON_RUNQUEUE_WEIGHT 30
90 #define CHILD_PENALTY 95
91 #define PARENT_PENALTY 100
93 #define PRIO_BONUS_RATIO 25
94 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
95 #define INTERACTIVE_DELTA 2
96 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
97 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
98 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
101 * If a task is 'interactive' then we reinsert it in the active
102 * array after it has expired its current timeslice. (it will not
103 * continue to run immediately, it will still roundrobin with
104 * other interactive tasks.)
106 * This part scales the interactivity limit depending on niceness.
108 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
109 * Here are a few examples of different nice levels:
111 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
112 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
113 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
114 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
115 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
117 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
118 * priority range a task can explore, a value of '1' means the
119 * task is rated interactive.)
121 * Ie. nice +19 tasks can never get 'interactive' enough to be
122 * reinserted into the active array. And only heavily CPU-hog nice -20
123 * tasks will be expired. Default nice 0 tasks are somewhere between,
124 * it takes some effort for them to get interactive, but it's not
128 #define CURRENT_BONUS(p) \
129 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
132 #define GRANULARITY (10 * HZ / 1000 ? : 1)
135 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
136 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
139 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
140 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
143 #define SCALE(v1,v1_max,v2_max) \
144 (v1) * (v2_max) / (v1_max)
147 (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
149 #define TASK_INTERACTIVE(p) \
150 ((p)->prio <= (p)->static_prio - DELTA(p))
152 #define INTERACTIVE_SLEEP(p) \
153 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
154 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
156 #define TASK_PREEMPTS_CURR(p, rq) \
157 ((p)->prio < (rq)->curr->prio)
160 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
161 * to time slice values: [800ms ... 100ms ... 5ms]
163 * The higher a thread's priority, the bigger timeslices
164 * it gets during one round of execution. But even the lowest
165 * priority thread gets MIN_TIMESLICE worth of execution time.
168 #define SCALE_PRIO(x, prio) \
169 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
171 static unsigned int task_timeslice(task_t
*p
)
173 if (p
->static_prio
< NICE_TO_PRIO(0))
174 return SCALE_PRIO(DEF_TIMESLICE
*4, p
->static_prio
);
176 return SCALE_PRIO(DEF_TIMESLICE
, p
->static_prio
);
178 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
179 < (long long) (sd)->cache_hot_time)
181 void __put_task_struct_cb(struct rcu_head
*rhp
)
183 __put_task_struct(container_of(rhp
, struct task_struct
, rcu
));
186 EXPORT_SYMBOL_GPL(__put_task_struct_cb
);
189 * These are the runqueue data structures:
192 #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
194 typedef struct runqueue runqueue_t
;
197 unsigned int nr_active
;
198 unsigned long bitmap
[BITMAP_SIZE
];
199 struct list_head queue
[MAX_PRIO
];
203 * This is the main, per-CPU runqueue data structure.
205 * Locking rule: those places that want to lock multiple runqueues
206 * (such as the load balancing or the thread migration code), lock
207 * acquire operations must be ordered by ascending &runqueue.
213 * nr_running and cpu_load should be in the same cacheline because
214 * remote CPUs use both these fields when doing load calculation.
216 unsigned long nr_running
;
218 unsigned long prio_bias
;
219 unsigned long cpu_load
[3];
221 unsigned long long nr_switches
;
224 * This is part of a global counter where only the total sum
225 * over all CPUs matters. A task can increase this counter on
226 * one CPU and if it got migrated afterwards it may decrease
227 * it on another CPU. Always updated under the runqueue lock:
229 unsigned long nr_uninterruptible
;
231 unsigned long expired_timestamp
;
232 unsigned long long timestamp_last_tick
;
234 struct mm_struct
*prev_mm
;
235 prio_array_t
*active
, *expired
, arrays
[2];
236 int best_expired_prio
;
240 struct sched_domain
*sd
;
242 /* For active balancing */
246 task_t
*migration_thread
;
247 struct list_head migration_queue
;
250 #ifdef CONFIG_SCHEDSTATS
252 struct sched_info rq_sched_info
;
254 /* sys_sched_yield() stats */
255 unsigned long yld_exp_empty
;
256 unsigned long yld_act_empty
;
257 unsigned long yld_both_empty
;
258 unsigned long yld_cnt
;
260 /* schedule() stats */
261 unsigned long sched_switch
;
262 unsigned long sched_cnt
;
263 unsigned long sched_goidle
;
265 /* try_to_wake_up() stats */
266 unsigned long ttwu_cnt
;
267 unsigned long ttwu_local
;
271 static DEFINE_PER_CPU(struct runqueue
, runqueues
);
274 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
275 * See detach_destroy_domains: synchronize_sched for details.
277 * The domain tree of any CPU may only be accessed from within
278 * preempt-disabled sections.
280 #define for_each_domain(cpu, domain) \
281 for (domain = rcu_dereference(cpu_rq(cpu)->sd); domain; domain = domain->parent)
283 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
284 #define this_rq() (&__get_cpu_var(runqueues))
285 #define task_rq(p) cpu_rq(task_cpu(p))
286 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
288 #ifndef prepare_arch_switch
289 # define prepare_arch_switch(next) do { } while (0)
291 #ifndef finish_arch_switch
292 # define finish_arch_switch(prev) do { } while (0)
295 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
296 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
298 return rq
->curr
== p
;
301 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
305 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
307 #ifdef CONFIG_DEBUG_SPINLOCK
308 /* this is a valid case when another task releases the spinlock */
309 rq
->lock
.owner
= current
;
311 spin_unlock_irq(&rq
->lock
);
314 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
315 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
320 return rq
->curr
== p
;
324 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
328 * We can optimise this out completely for !SMP, because the
329 * SMP rebalancing from interrupt is the only thing that cares
334 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
335 spin_unlock_irq(&rq
->lock
);
337 spin_unlock(&rq
->lock
);
341 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
345 * After ->oncpu is cleared, the task can be moved to a different CPU.
346 * We must ensure this doesn't happen until the switch is completely
352 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
356 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
359 * task_rq_lock - lock the runqueue a given task resides on and disable
360 * interrupts. Note the ordering: we can safely lookup the task_rq without
361 * explicitly disabling preemption.
363 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
369 local_irq_save(*flags
);
371 spin_lock(&rq
->lock
);
372 if (unlikely(rq
!= task_rq(p
))) {
373 spin_unlock_irqrestore(&rq
->lock
, *flags
);
374 goto repeat_lock_task
;
379 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
382 spin_unlock_irqrestore(&rq
->lock
, *flags
);
385 #ifdef CONFIG_SCHEDSTATS
387 * bump this up when changing the output format or the meaning of an existing
388 * format, so that tools can adapt (or abort)
390 #define SCHEDSTAT_VERSION 12
392 static int show_schedstat(struct seq_file
*seq
, void *v
)
396 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
397 seq_printf(seq
, "timestamp %lu\n", jiffies
);
398 for_each_online_cpu(cpu
) {
399 runqueue_t
*rq
= cpu_rq(cpu
);
401 struct sched_domain
*sd
;
405 /* runqueue-specific stats */
407 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
408 cpu
, rq
->yld_both_empty
,
409 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
410 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
411 rq
->ttwu_cnt
, rq
->ttwu_local
,
412 rq
->rq_sched_info
.cpu_time
,
413 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
415 seq_printf(seq
, "\n");
418 /* domain-specific stats */
420 for_each_domain(cpu
, sd
) {
421 enum idle_type itype
;
422 char mask_str
[NR_CPUS
];
424 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
425 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
426 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
428 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
430 sd
->lb_balanced
[itype
],
431 sd
->lb_failed
[itype
],
432 sd
->lb_imbalance
[itype
],
433 sd
->lb_gained
[itype
],
434 sd
->lb_hot_gained
[itype
],
435 sd
->lb_nobusyq
[itype
],
436 sd
->lb_nobusyg
[itype
]);
438 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
439 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
440 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
441 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
442 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
450 static int schedstat_open(struct inode
*inode
, struct file
*file
)
452 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
453 char *buf
= kmalloc(size
, GFP_KERNEL
);
459 res
= single_open(file
, show_schedstat
, NULL
);
461 m
= file
->private_data
;
469 struct file_operations proc_schedstat_operations
= {
470 .open
= schedstat_open
,
473 .release
= single_release
,
476 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
477 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
478 #else /* !CONFIG_SCHEDSTATS */
479 # define schedstat_inc(rq, field) do { } while (0)
480 # define schedstat_add(rq, field, amt) do { } while (0)
484 * rq_lock - lock a given runqueue and disable interrupts.
486 static inline runqueue_t
*this_rq_lock(void)
493 spin_lock(&rq
->lock
);
498 #ifdef CONFIG_SCHEDSTATS
500 * Called when a process is dequeued from the active array and given
501 * the cpu. We should note that with the exception of interactive
502 * tasks, the expired queue will become the active queue after the active
503 * queue is empty, without explicitly dequeuing and requeuing tasks in the
504 * expired queue. (Interactive tasks may be requeued directly to the
505 * active queue, thus delaying tasks in the expired queue from running;
506 * see scheduler_tick()).
508 * This function is only called from sched_info_arrive(), rather than
509 * dequeue_task(). Even though a task may be queued and dequeued multiple
510 * times as it is shuffled about, we're really interested in knowing how
511 * long it was from the *first* time it was queued to the time that it
514 static inline void sched_info_dequeued(task_t
*t
)
516 t
->sched_info
.last_queued
= 0;
520 * Called when a task finally hits the cpu. We can now calculate how
521 * long it was waiting to run. We also note when it began so that we
522 * can keep stats on how long its timeslice is.
524 static inline void sched_info_arrive(task_t
*t
)
526 unsigned long now
= jiffies
, diff
= 0;
527 struct runqueue
*rq
= task_rq(t
);
529 if (t
->sched_info
.last_queued
)
530 diff
= now
- t
->sched_info
.last_queued
;
531 sched_info_dequeued(t
);
532 t
->sched_info
.run_delay
+= diff
;
533 t
->sched_info
.last_arrival
= now
;
534 t
->sched_info
.pcnt
++;
539 rq
->rq_sched_info
.run_delay
+= diff
;
540 rq
->rq_sched_info
.pcnt
++;
544 * Called when a process is queued into either the active or expired
545 * array. The time is noted and later used to determine how long we
546 * had to wait for us to reach the cpu. Since the expired queue will
547 * become the active queue after active queue is empty, without dequeuing
548 * and requeuing any tasks, we are interested in queuing to either. It
549 * is unusual but not impossible for tasks to be dequeued and immediately
550 * requeued in the same or another array: this can happen in sched_yield(),
551 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
554 * This function is only called from enqueue_task(), but also only updates
555 * the timestamp if it is already not set. It's assumed that
556 * sched_info_dequeued() will clear that stamp when appropriate.
558 static inline void sched_info_queued(task_t
*t
)
560 if (!t
->sched_info
.last_queued
)
561 t
->sched_info
.last_queued
= jiffies
;
565 * Called when a process ceases being the active-running process, either
566 * voluntarily or involuntarily. Now we can calculate how long we ran.
568 static inline void sched_info_depart(task_t
*t
)
570 struct runqueue
*rq
= task_rq(t
);
571 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
573 t
->sched_info
.cpu_time
+= diff
;
576 rq
->rq_sched_info
.cpu_time
+= diff
;
580 * Called when tasks are switched involuntarily due, typically, to expiring
581 * their time slice. (This may also be called when switching to or from
582 * the idle task.) We are only called when prev != next.
584 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
586 struct runqueue
*rq
= task_rq(prev
);
589 * prev now departs the cpu. It's not interesting to record
590 * stats about how efficient we were at scheduling the idle
593 if (prev
!= rq
->idle
)
594 sched_info_depart(prev
);
596 if (next
!= rq
->idle
)
597 sched_info_arrive(next
);
600 #define sched_info_queued(t) do { } while (0)
601 #define sched_info_switch(t, next) do { } while (0)
602 #endif /* CONFIG_SCHEDSTATS */
605 * Adding/removing a task to/from a priority array:
607 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
610 list_del(&p
->run_list
);
611 if (list_empty(array
->queue
+ p
->prio
))
612 __clear_bit(p
->prio
, array
->bitmap
);
615 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
617 sched_info_queued(p
);
618 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
619 __set_bit(p
->prio
, array
->bitmap
);
625 * Put task to the end of the run list without the overhead of dequeue
626 * followed by enqueue.
628 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
630 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
633 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
635 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
636 __set_bit(p
->prio
, array
->bitmap
);
642 * effective_prio - return the priority that is based on the static
643 * priority but is modified by bonuses/penalties.
645 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
646 * into the -5 ... 0 ... +5 bonus/penalty range.
648 * We use 25% of the full 0...39 priority range so that:
650 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
651 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
653 * Both properties are important to certain workloads.
655 static int effective_prio(task_t
*p
)
662 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
664 prio
= p
->static_prio
- bonus
;
665 if (prio
< MAX_RT_PRIO
)
667 if (prio
> MAX_PRIO
-1)
673 static inline void inc_prio_bias(runqueue_t
*rq
, int prio
)
675 rq
->prio_bias
+= MAX_PRIO
- prio
;
678 static inline void dec_prio_bias(runqueue_t
*rq
, int prio
)
680 rq
->prio_bias
-= MAX_PRIO
- prio
;
683 static inline void inc_nr_running(task_t
*p
, runqueue_t
*rq
)
687 if (p
!= rq
->migration_thread
)
689 * The migration thread does the actual balancing. Do
690 * not bias by its priority as the ultra high priority
691 * will skew balancing adversely.
693 inc_prio_bias(rq
, p
->prio
);
695 inc_prio_bias(rq
, p
->static_prio
);
698 static inline void dec_nr_running(task_t
*p
, runqueue_t
*rq
)
702 if (p
!= rq
->migration_thread
)
703 dec_prio_bias(rq
, p
->prio
);
705 dec_prio_bias(rq
, p
->static_prio
);
708 static inline void inc_prio_bias(runqueue_t
*rq
, int prio
)
712 static inline void dec_prio_bias(runqueue_t
*rq
, int prio
)
716 static inline void inc_nr_running(task_t
*p
, runqueue_t
*rq
)
721 static inline void dec_nr_running(task_t
*p
, runqueue_t
*rq
)
728 * __activate_task - move a task to the runqueue.
730 static inline void __activate_task(task_t
*p
, runqueue_t
*rq
)
732 enqueue_task(p
, rq
->active
);
733 inc_nr_running(p
, rq
);
737 * __activate_idle_task - move idle task to the _front_ of runqueue.
739 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
741 enqueue_task_head(p
, rq
->active
);
742 inc_nr_running(p
, rq
);
745 static int recalc_task_prio(task_t
*p
, unsigned long long now
)
747 /* Caller must always ensure 'now >= p->timestamp' */
748 unsigned long long __sleep_time
= now
- p
->timestamp
;
749 unsigned long sleep_time
;
751 if (__sleep_time
> NS_MAX_SLEEP_AVG
)
752 sleep_time
= NS_MAX_SLEEP_AVG
;
754 sleep_time
= (unsigned long)__sleep_time
;
756 if (likely(sleep_time
> 0)) {
758 * User tasks that sleep a long time are categorised as
759 * idle and will get just interactive status to stay active &
760 * prevent them suddenly becoming cpu hogs and starving
763 if (p
->mm
&& p
->activated
!= -1 &&
764 sleep_time
> INTERACTIVE_SLEEP(p
)) {
765 p
->sleep_avg
= JIFFIES_TO_NS(MAX_SLEEP_AVG
-
769 * The lower the sleep avg a task has the more
770 * rapidly it will rise with sleep time.
772 sleep_time
*= (MAX_BONUS
- CURRENT_BONUS(p
)) ? : 1;
775 * Tasks waking from uninterruptible sleep are
776 * limited in their sleep_avg rise as they
777 * are likely to be waiting on I/O
779 if (p
->activated
== -1 && p
->mm
) {
780 if (p
->sleep_avg
>= INTERACTIVE_SLEEP(p
))
782 else if (p
->sleep_avg
+ sleep_time
>=
783 INTERACTIVE_SLEEP(p
)) {
784 p
->sleep_avg
= INTERACTIVE_SLEEP(p
);
790 * This code gives a bonus to interactive tasks.
792 * The boost works by updating the 'average sleep time'
793 * value here, based on ->timestamp. The more time a
794 * task spends sleeping, the higher the average gets -
795 * and the higher the priority boost gets as well.
797 p
->sleep_avg
+= sleep_time
;
799 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
800 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
804 return effective_prio(p
);
808 * activate_task - move a task to the runqueue and do priority recalculation
810 * Update all the scheduling statistics stuff. (sleep average
811 * calculation, priority modifiers, etc.)
813 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
815 unsigned long long now
;
820 /* Compensate for drifting sched_clock */
821 runqueue_t
*this_rq
= this_rq();
822 now
= (now
- this_rq
->timestamp_last_tick
)
823 + rq
->timestamp_last_tick
;
828 p
->prio
= recalc_task_prio(p
, now
);
831 * This checks to make sure it's not an uninterruptible task
832 * that is now waking up.
836 * Tasks which were woken up by interrupts (ie. hw events)
837 * are most likely of interactive nature. So we give them
838 * the credit of extending their sleep time to the period
839 * of time they spend on the runqueue, waiting for execution
840 * on a CPU, first time around:
846 * Normal first-time wakeups get a credit too for
847 * on-runqueue time, but it will be weighted down:
854 __activate_task(p
, rq
);
858 * deactivate_task - remove a task from the runqueue.
860 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
862 dec_nr_running(p
, rq
);
863 dequeue_task(p
, p
->array
);
868 * resched_task - mark a task 'to be rescheduled now'.
870 * On UP this means the setting of the need_resched flag, on SMP it
871 * might also involve a cross-CPU call to trigger the scheduler on
875 static void resched_task(task_t
*p
)
879 assert_spin_locked(&task_rq(p
)->lock
);
881 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
884 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
887 if (cpu
== smp_processor_id())
890 /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */
892 if (!test_tsk_thread_flag(p
, TIF_POLLING_NRFLAG
))
893 smp_send_reschedule(cpu
);
896 static inline void resched_task(task_t
*p
)
898 assert_spin_locked(&task_rq(p
)->lock
);
899 set_tsk_need_resched(p
);
904 * task_curr - is this task currently executing on a CPU?
905 * @p: the task in question.
907 inline int task_curr(const task_t
*p
)
909 return cpu_curr(task_cpu(p
)) == p
;
914 struct list_head list
;
919 struct completion done
;
923 * The task's runqueue lock must be held.
924 * Returns true if you have to wait for migration thread.
926 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
928 runqueue_t
*rq
= task_rq(p
);
931 * If the task is not on a runqueue (and not running), then
932 * it is sufficient to simply update the task's cpu field.
934 if (!p
->array
&& !task_running(rq
, p
)) {
935 set_task_cpu(p
, dest_cpu
);
939 init_completion(&req
->done
);
941 req
->dest_cpu
= dest_cpu
;
942 list_add(&req
->list
, &rq
->migration_queue
);
947 * wait_task_inactive - wait for a thread to unschedule.
949 * The caller must ensure that the task *will* unschedule sometime soon,
950 * else this function might spin for a *long* time. This function can't
951 * be called with interrupts off, or it may introduce deadlock with
952 * smp_call_function() if an IPI is sent by the same process we are
953 * waiting to become inactive.
955 void wait_task_inactive(task_t
*p
)
962 rq
= task_rq_lock(p
, &flags
);
963 /* Must be off runqueue entirely, not preempted. */
964 if (unlikely(p
->array
|| task_running(rq
, p
))) {
965 /* If it's preempted, we yield. It could be a while. */
966 preempted
= !task_running(rq
, p
);
967 task_rq_unlock(rq
, &flags
);
973 task_rq_unlock(rq
, &flags
);
977 * kick_process - kick a running thread to enter/exit the kernel
978 * @p: the to-be-kicked thread
980 * Cause a process which is running on another CPU to enter
981 * kernel-mode, without any delay. (to get signals handled.)
983 * NOTE: this function doesnt have to take the runqueue lock,
984 * because all it wants to ensure is that the remote task enters
985 * the kernel. If the IPI races and the task has been migrated
986 * to another CPU then no harm is done and the purpose has been
989 void kick_process(task_t
*p
)
995 if ((cpu
!= smp_processor_id()) && task_curr(p
))
996 smp_send_reschedule(cpu
);
1001 * Return a low guess at the load of a migration-source cpu.
1003 * We want to under-estimate the load of migration sources, to
1004 * balance conservatively.
1006 static inline unsigned long __source_load(int cpu
, int type
, enum idle_type idle
)
1008 runqueue_t
*rq
= cpu_rq(cpu
);
1009 unsigned long running
= rq
->nr_running
;
1010 unsigned long source_load
, cpu_load
= rq
->cpu_load
[type
-1],
1011 load_now
= running
* SCHED_LOAD_SCALE
;
1014 source_load
= load_now
;
1016 source_load
= min(cpu_load
, load_now
);
1018 if (running
> 1 || (idle
== NOT_IDLE
&& running
))
1020 * If we are busy rebalancing the load is biased by
1021 * priority to create 'nice' support across cpus. When
1022 * idle rebalancing we should only bias the source_load if
1023 * there is more than one task running on that queue to
1024 * prevent idle rebalance from trying to pull tasks from a
1025 * queue with only one running task.
1027 source_load
= source_load
* rq
->prio_bias
/ running
;
1032 static inline unsigned long source_load(int cpu
, int type
)
1034 return __source_load(cpu
, type
, NOT_IDLE
);
1038 * Return a high guess at the load of a migration-target cpu
1040 static inline unsigned long __target_load(int cpu
, int type
, enum idle_type idle
)
1042 runqueue_t
*rq
= cpu_rq(cpu
);
1043 unsigned long running
= rq
->nr_running
;
1044 unsigned long target_load
, cpu_load
= rq
->cpu_load
[type
-1],
1045 load_now
= running
* SCHED_LOAD_SCALE
;
1048 target_load
= load_now
;
1050 target_load
= max(cpu_load
, load_now
);
1052 if (running
> 1 || (idle
== NOT_IDLE
&& running
))
1053 target_load
= target_load
* rq
->prio_bias
/ running
;
1058 static inline unsigned long target_load(int cpu
, int type
)
1060 return __target_load(cpu
, type
, NOT_IDLE
);
1064 * find_idlest_group finds and returns the least busy CPU group within the
1067 static struct sched_group
*
1068 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1070 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1071 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1072 int load_idx
= sd
->forkexec_idx
;
1073 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1076 unsigned long load
, avg_load
;
1080 /* Skip over this group if it has no CPUs allowed */
1081 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1084 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1086 /* Tally up the load of all CPUs in the group */
1089 for_each_cpu_mask(i
, group
->cpumask
) {
1090 /* Bias balancing toward cpus of our domain */
1092 load
= source_load(i
, load_idx
);
1094 load
= target_load(i
, load_idx
);
1099 /* Adjust by relative CPU power of the group */
1100 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1103 this_load
= avg_load
;
1105 } else if (avg_load
< min_load
) {
1106 min_load
= avg_load
;
1110 group
= group
->next
;
1111 } while (group
!= sd
->groups
);
1113 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1119 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1122 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1125 unsigned long load
, min_load
= ULONG_MAX
;
1129 /* Traverse only the allowed CPUs */
1130 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1132 for_each_cpu_mask(i
, tmp
) {
1133 load
= source_load(i
, 0);
1135 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1145 * sched_balance_self: balance the current task (running on cpu) in domains
1146 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1149 * Balance, ie. select the least loaded group.
1151 * Returns the target CPU number, or the same CPU if no balancing is needed.
1153 * preempt must be disabled.
1155 static int sched_balance_self(int cpu
, int flag
)
1157 struct task_struct
*t
= current
;
1158 struct sched_domain
*tmp
, *sd
= NULL
;
1160 for_each_domain(cpu
, tmp
)
1161 if (tmp
->flags
& flag
)
1166 struct sched_group
*group
;
1171 group
= find_idlest_group(sd
, t
, cpu
);
1175 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1176 if (new_cpu
== -1 || new_cpu
== cpu
)
1179 /* Now try balancing at a lower domain level */
1183 weight
= cpus_weight(span
);
1184 for_each_domain(cpu
, tmp
) {
1185 if (weight
<= cpus_weight(tmp
->span
))
1187 if (tmp
->flags
& flag
)
1190 /* while loop will break here if sd == NULL */
1196 #endif /* CONFIG_SMP */
1199 * wake_idle() will wake a task on an idle cpu if task->cpu is
1200 * not idle and an idle cpu is available. The span of cpus to
1201 * search starts with cpus closest then further out as needed,
1202 * so we always favor a closer, idle cpu.
1204 * Returns the CPU we should wake onto.
1206 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1207 static int wake_idle(int cpu
, task_t
*p
)
1210 struct sched_domain
*sd
;
1216 for_each_domain(cpu
, sd
) {
1217 if (sd
->flags
& SD_WAKE_IDLE
) {
1218 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1219 for_each_cpu_mask(i
, tmp
) {
1230 static inline int wake_idle(int cpu
, task_t
*p
)
1237 * try_to_wake_up - wake up a thread
1238 * @p: the to-be-woken-up thread
1239 * @state: the mask of task states that can be woken
1240 * @sync: do a synchronous wakeup?
1242 * Put it on the run-queue if it's not already there. The "current"
1243 * thread is always on the run-queue (except when the actual
1244 * re-schedule is in progress), and as such you're allowed to do
1245 * the simpler "current->state = TASK_RUNNING" to mark yourself
1246 * runnable without the overhead of this.
1248 * returns failure only if the task is already active.
1250 static int try_to_wake_up(task_t
*p
, unsigned int state
, int sync
)
1252 int cpu
, this_cpu
, success
= 0;
1253 unsigned long flags
;
1257 unsigned long load
, this_load
;
1258 struct sched_domain
*sd
, *this_sd
= NULL
;
1262 rq
= task_rq_lock(p
, &flags
);
1263 old_state
= p
->state
;
1264 if (!(old_state
& state
))
1271 this_cpu
= smp_processor_id();
1274 if (unlikely(task_running(rq
, p
)))
1279 schedstat_inc(rq
, ttwu_cnt
);
1280 if (cpu
== this_cpu
) {
1281 schedstat_inc(rq
, ttwu_local
);
1285 for_each_domain(this_cpu
, sd
) {
1286 if (cpu_isset(cpu
, sd
->span
)) {
1287 schedstat_inc(sd
, ttwu_wake_remote
);
1293 if (p
->last_waker_cpu
!= this_cpu
)
1296 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1300 * Check for affine wakeup and passive balancing possibilities.
1303 int idx
= this_sd
->wake_idx
;
1304 unsigned int imbalance
;
1306 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1308 load
= source_load(cpu
, idx
);
1309 this_load
= target_load(this_cpu
, idx
);
1311 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1313 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1314 unsigned long tl
= this_load
;
1316 * If sync wakeup then subtract the (maximum possible)
1317 * effect of the currently running task from the load
1318 * of the current CPU:
1321 tl
-= SCHED_LOAD_SCALE
;
1324 tl
+ target_load(cpu
, idx
) <= SCHED_LOAD_SCALE
) ||
1325 100*(tl
+ SCHED_LOAD_SCALE
) <= imbalance
*load
) {
1327 * This domain has SD_WAKE_AFFINE and
1328 * p is cache cold in this domain, and
1329 * there is no bad imbalance.
1331 schedstat_inc(this_sd
, ttwu_move_affine
);
1337 * Start passive balancing when half the imbalance_pct
1340 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1341 if (imbalance
*this_load
<= 100*load
) {
1342 schedstat_inc(this_sd
, ttwu_move_balance
);
1348 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1350 new_cpu
= wake_idle(new_cpu
, p
);
1351 if (new_cpu
!= cpu
) {
1352 set_task_cpu(p
, new_cpu
);
1353 task_rq_unlock(rq
, &flags
);
1354 /* might preempt at this point */
1355 rq
= task_rq_lock(p
, &flags
);
1356 old_state
= p
->state
;
1357 if (!(old_state
& state
))
1362 this_cpu
= smp_processor_id();
1366 p
->last_waker_cpu
= this_cpu
;
1369 #endif /* CONFIG_SMP */
1370 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1371 rq
->nr_uninterruptible
--;
1373 * Tasks on involuntary sleep don't earn
1374 * sleep_avg beyond just interactive state.
1380 * Tasks that have marked their sleep as noninteractive get
1381 * woken up without updating their sleep average. (i.e. their
1382 * sleep is handled in a priority-neutral manner, no priority
1383 * boost and no penalty.)
1385 if (old_state
& TASK_NONINTERACTIVE
)
1386 __activate_task(p
, rq
);
1388 activate_task(p
, rq
, cpu
== this_cpu
);
1390 * Sync wakeups (i.e. those types of wakeups where the waker
1391 * has indicated that it will leave the CPU in short order)
1392 * don't trigger a preemption, if the woken up task will run on
1393 * this cpu. (in this case the 'I will reschedule' promise of
1394 * the waker guarantees that the freshly woken up task is going
1395 * to be considered on this CPU.)
1397 if (!sync
|| cpu
!= this_cpu
) {
1398 if (TASK_PREEMPTS_CURR(p
, rq
))
1399 resched_task(rq
->curr
);
1404 p
->state
= TASK_RUNNING
;
1406 task_rq_unlock(rq
, &flags
);
1411 int fastcall
wake_up_process(task_t
*p
)
1413 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1414 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1417 EXPORT_SYMBOL(wake_up_process
);
1419 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1421 return try_to_wake_up(p
, state
, 0);
1425 * Perform scheduler related setup for a newly forked process p.
1426 * p is forked by current.
1428 void fastcall
sched_fork(task_t
*p
, int clone_flags
)
1430 int cpu
= get_cpu();
1433 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1435 set_task_cpu(p
, cpu
);
1438 * We mark the process as running here, but have not actually
1439 * inserted it onto the runqueue yet. This guarantees that
1440 * nobody will actually run it, and a signal or other external
1441 * event cannot wake it up and insert it on the runqueue either.
1443 p
->state
= TASK_RUNNING
;
1444 INIT_LIST_HEAD(&p
->run_list
);
1446 #ifdef CONFIG_SCHEDSTATS
1447 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1449 #if defined(CONFIG_SMP)
1450 p
->last_waker_cpu
= cpu
;
1451 #if defined(__ARCH_WANT_UNLOCKED_CTXSW)
1455 #ifdef CONFIG_PREEMPT
1456 /* Want to start with kernel preemption disabled. */
1457 task_thread_info(p
)->preempt_count
= 1;
1460 * Share the timeslice between parent and child, thus the
1461 * total amount of pending timeslices in the system doesn't change,
1462 * resulting in more scheduling fairness.
1464 local_irq_disable();
1465 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1467 * The remainder of the first timeslice might be recovered by
1468 * the parent if the child exits early enough.
1470 p
->first_time_slice
= 1;
1471 current
->time_slice
>>= 1;
1472 p
->timestamp
= sched_clock();
1473 if (unlikely(!current
->time_slice
)) {
1475 * This case is rare, it happens when the parent has only
1476 * a single jiffy left from its timeslice. Taking the
1477 * runqueue lock is not a problem.
1479 current
->time_slice
= 1;
1487 * wake_up_new_task - wake up a newly created task for the first time.
1489 * This function will do some initial scheduler statistics housekeeping
1490 * that must be done for every newly created context, then puts the task
1491 * on the runqueue and wakes it.
1493 void fastcall
wake_up_new_task(task_t
*p
, unsigned long clone_flags
)
1495 unsigned long flags
;
1497 runqueue_t
*rq
, *this_rq
;
1499 rq
= task_rq_lock(p
, &flags
);
1500 BUG_ON(p
->state
!= TASK_RUNNING
);
1501 this_cpu
= smp_processor_id();
1505 * We decrease the sleep average of forking parents
1506 * and children as well, to keep max-interactive tasks
1507 * from forking tasks that are max-interactive. The parent
1508 * (current) is done further down, under its lock.
1510 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1511 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1513 p
->prio
= effective_prio(p
);
1515 if (likely(cpu
== this_cpu
)) {
1516 if (!(clone_flags
& CLONE_VM
)) {
1518 * The VM isn't cloned, so we're in a good position to
1519 * do child-runs-first in anticipation of an exec. This
1520 * usually avoids a lot of COW overhead.
1522 if (unlikely(!current
->array
))
1523 __activate_task(p
, rq
);
1525 p
->prio
= current
->prio
;
1526 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1527 p
->array
= current
->array
;
1528 p
->array
->nr_active
++;
1529 inc_nr_running(p
, rq
);
1533 /* Run child last */
1534 __activate_task(p
, rq
);
1536 * We skip the following code due to cpu == this_cpu
1538 * task_rq_unlock(rq, &flags);
1539 * this_rq = task_rq_lock(current, &flags);
1543 this_rq
= cpu_rq(this_cpu
);
1546 * Not the local CPU - must adjust timestamp. This should
1547 * get optimised away in the !CONFIG_SMP case.
1549 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1550 + rq
->timestamp_last_tick
;
1551 __activate_task(p
, rq
);
1552 if (TASK_PREEMPTS_CURR(p
, rq
))
1553 resched_task(rq
->curr
);
1556 * Parent and child are on different CPUs, now get the
1557 * parent runqueue to update the parent's ->sleep_avg:
1559 task_rq_unlock(rq
, &flags
);
1560 this_rq
= task_rq_lock(current
, &flags
);
1562 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1563 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1564 task_rq_unlock(this_rq
, &flags
);
1568 * Potentially available exiting-child timeslices are
1569 * retrieved here - this way the parent does not get
1570 * penalized for creating too many threads.
1572 * (this cannot be used to 'generate' timeslices
1573 * artificially, because any timeslice recovered here
1574 * was given away by the parent in the first place.)
1576 void fastcall
sched_exit(task_t
*p
)
1578 unsigned long flags
;
1582 * If the child was a (relative-) CPU hog then decrease
1583 * the sleep_avg of the parent as well.
1585 rq
= task_rq_lock(p
->parent
, &flags
);
1586 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1587 p
->parent
->time_slice
+= p
->time_slice
;
1588 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1589 p
->parent
->time_slice
= task_timeslice(p
);
1591 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1592 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1593 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1595 task_rq_unlock(rq
, &flags
);
1599 * prepare_task_switch - prepare to switch tasks
1600 * @rq: the runqueue preparing to switch
1601 * @next: the task we are going to switch to.
1603 * This is called with the rq lock held and interrupts off. It must
1604 * be paired with a subsequent finish_task_switch after the context
1607 * prepare_task_switch sets up locking and calls architecture specific
1610 static inline void prepare_task_switch(runqueue_t
*rq
, task_t
*next
)
1612 prepare_lock_switch(rq
, next
);
1613 prepare_arch_switch(next
);
1617 * finish_task_switch - clean up after a task-switch
1618 * @rq: runqueue associated with task-switch
1619 * @prev: the thread we just switched away from.
1621 * finish_task_switch must be called after the context switch, paired
1622 * with a prepare_task_switch call before the context switch.
1623 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1624 * and do any other architecture-specific cleanup actions.
1626 * Note that we may have delayed dropping an mm in context_switch(). If
1627 * so, we finish that here outside of the runqueue lock. (Doing it
1628 * with the lock held can cause deadlocks; see schedule() for
1631 static inline void finish_task_switch(runqueue_t
*rq
, task_t
*prev
)
1632 __releases(rq
->lock
)
1634 struct mm_struct
*mm
= rq
->prev_mm
;
1635 unsigned long prev_task_flags
;
1640 * A task struct has one reference for the use as "current".
1641 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1642 * calls schedule one last time. The schedule call will never return,
1643 * and the scheduled task must drop that reference.
1644 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1645 * still held, otherwise prev could be scheduled on another cpu, die
1646 * there before we look at prev->state, and then the reference would
1648 * Manfred Spraul <manfred@colorfullife.com>
1650 prev_task_flags
= prev
->flags
;
1651 finish_arch_switch(prev
);
1652 finish_lock_switch(rq
, prev
);
1655 if (unlikely(prev_task_flags
& PF_DEAD
))
1656 put_task_struct(prev
);
1660 * schedule_tail - first thing a freshly forked thread must call.
1661 * @prev: the thread we just switched away from.
1663 asmlinkage
void schedule_tail(task_t
*prev
)
1664 __releases(rq
->lock
)
1666 runqueue_t
*rq
= this_rq();
1667 finish_task_switch(rq
, prev
);
1668 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1669 /* In this case, finish_task_switch does not reenable preemption */
1672 if (current
->set_child_tid
)
1673 put_user(current
->pid
, current
->set_child_tid
);
1677 * context_switch - switch to the new MM and the new
1678 * thread's register state.
1681 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1683 struct mm_struct
*mm
= next
->mm
;
1684 struct mm_struct
*oldmm
= prev
->active_mm
;
1686 if (unlikely(!mm
)) {
1687 next
->active_mm
= oldmm
;
1688 atomic_inc(&oldmm
->mm_count
);
1689 enter_lazy_tlb(oldmm
, next
);
1691 switch_mm(oldmm
, mm
, next
);
1693 if (unlikely(!prev
->mm
)) {
1694 prev
->active_mm
= NULL
;
1695 WARN_ON(rq
->prev_mm
);
1696 rq
->prev_mm
= oldmm
;
1699 /* Here we just switch the register state and the stack. */
1700 switch_to(prev
, next
, prev
);
1706 * nr_running, nr_uninterruptible and nr_context_switches:
1708 * externally visible scheduler statistics: current number of runnable
1709 * threads, current number of uninterruptible-sleeping threads, total
1710 * number of context switches performed since bootup.
1712 unsigned long nr_running(void)
1714 unsigned long i
, sum
= 0;
1716 for_each_online_cpu(i
)
1717 sum
+= cpu_rq(i
)->nr_running
;
1722 unsigned long nr_uninterruptible(void)
1724 unsigned long i
, sum
= 0;
1727 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1730 * Since we read the counters lockless, it might be slightly
1731 * inaccurate. Do not allow it to go below zero though:
1733 if (unlikely((long)sum
< 0))
1739 unsigned long long nr_context_switches(void)
1741 unsigned long long i
, sum
= 0;
1744 sum
+= cpu_rq(i
)->nr_switches
;
1749 unsigned long nr_iowait(void)
1751 unsigned long i
, sum
= 0;
1754 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1762 * double_rq_lock - safely lock two runqueues
1764 * Note this does not disable interrupts like task_rq_lock,
1765 * you need to do so manually before calling.
1767 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1768 __acquires(rq1
->lock
)
1769 __acquires(rq2
->lock
)
1772 spin_lock(&rq1
->lock
);
1773 __acquire(rq2
->lock
); /* Fake it out ;) */
1776 spin_lock(&rq1
->lock
);
1777 spin_lock(&rq2
->lock
);
1779 spin_lock(&rq2
->lock
);
1780 spin_lock(&rq1
->lock
);
1786 * double_rq_unlock - safely unlock two runqueues
1788 * Note this does not restore interrupts like task_rq_unlock,
1789 * you need to do so manually after calling.
1791 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1792 __releases(rq1
->lock
)
1793 __releases(rq2
->lock
)
1795 spin_unlock(&rq1
->lock
);
1797 spin_unlock(&rq2
->lock
);
1799 __release(rq2
->lock
);
1803 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1805 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1806 __releases(this_rq
->lock
)
1807 __acquires(busiest
->lock
)
1808 __acquires(this_rq
->lock
)
1810 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1811 if (busiest
< this_rq
) {
1812 spin_unlock(&this_rq
->lock
);
1813 spin_lock(&busiest
->lock
);
1814 spin_lock(&this_rq
->lock
);
1816 spin_lock(&busiest
->lock
);
1821 * If dest_cpu is allowed for this process, migrate the task to it.
1822 * This is accomplished by forcing the cpu_allowed mask to only
1823 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1824 * the cpu_allowed mask is restored.
1826 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1828 migration_req_t req
;
1830 unsigned long flags
;
1832 rq
= task_rq_lock(p
, &flags
);
1833 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1834 || unlikely(cpu_is_offline(dest_cpu
)))
1837 /* force the process onto the specified CPU */
1838 if (migrate_task(p
, dest_cpu
, &req
)) {
1839 /* Need to wait for migration thread (might exit: take ref). */
1840 struct task_struct
*mt
= rq
->migration_thread
;
1841 get_task_struct(mt
);
1842 task_rq_unlock(rq
, &flags
);
1843 wake_up_process(mt
);
1844 put_task_struct(mt
);
1845 wait_for_completion(&req
.done
);
1849 task_rq_unlock(rq
, &flags
);
1853 * sched_exec - execve() is a valuable balancing opportunity, because at
1854 * this point the task has the smallest effective memory and cache footprint.
1856 void sched_exec(void)
1858 int new_cpu
, this_cpu
= get_cpu();
1859 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
1861 if (new_cpu
!= this_cpu
)
1862 sched_migrate_task(current
, new_cpu
);
1866 * pull_task - move a task from a remote runqueue to the local runqueue.
1867 * Both runqueues must be locked.
1870 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1871 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1873 dequeue_task(p
, src_array
);
1874 dec_nr_running(p
, src_rq
);
1875 set_task_cpu(p
, this_cpu
);
1876 inc_nr_running(p
, this_rq
);
1877 enqueue_task(p
, this_array
);
1878 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1879 + this_rq
->timestamp_last_tick
;
1881 * Note that idle threads have a prio of MAX_PRIO, for this test
1882 * to be always true for them.
1884 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1885 resched_task(this_rq
->curr
);
1889 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1892 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1893 struct sched_domain
*sd
, enum idle_type idle
,
1897 * We do not migrate tasks that are:
1898 * 1) running (obviously), or
1899 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1900 * 3) are cache-hot on their current CPU.
1902 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1906 if (task_running(rq
, p
))
1910 * Aggressive migration if:
1911 * 1) task is cache cold, or
1912 * 2) too many balance attempts have failed.
1915 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1918 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1924 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1925 * as part of a balancing operation within "domain". Returns the number of
1928 * Called with both runqueues locked.
1930 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1931 unsigned long max_nr_move
, struct sched_domain
*sd
,
1932 enum idle_type idle
, int *all_pinned
)
1934 prio_array_t
*array
, *dst_array
;
1935 struct list_head
*head
, *curr
;
1936 int idx
, pulled
= 0, pinned
= 0;
1939 if (max_nr_move
== 0)
1945 * We first consider expired tasks. Those will likely not be
1946 * executed in the near future, and they are most likely to
1947 * be cache-cold, thus switching CPUs has the least effect
1950 if (busiest
->expired
->nr_active
) {
1951 array
= busiest
->expired
;
1952 dst_array
= this_rq
->expired
;
1954 array
= busiest
->active
;
1955 dst_array
= this_rq
->active
;
1959 /* Start searching at priority 0: */
1963 idx
= sched_find_first_bit(array
->bitmap
);
1965 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1966 if (idx
>= MAX_PRIO
) {
1967 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1968 array
= busiest
->active
;
1969 dst_array
= this_rq
->active
;
1975 head
= array
->queue
+ idx
;
1978 tmp
= list_entry(curr
, task_t
, run_list
);
1982 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1989 #ifdef CONFIG_SCHEDSTATS
1990 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1991 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1994 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1997 /* We only want to steal up to the prescribed number of tasks. */
1998 if (pulled
< max_nr_move
) {
2006 * Right now, this is the only place pull_task() is called,
2007 * so we can safely collect pull_task() stats here rather than
2008 * inside pull_task().
2010 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2013 *all_pinned
= pinned
;
2018 * find_busiest_group finds and returns the busiest CPU group within the
2019 * domain. It calculates and returns the number of tasks which should be
2020 * moved to restore balance via the imbalance parameter.
2022 static struct sched_group
*
2023 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2024 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
)
2026 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2027 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2028 unsigned long max_pull
;
2031 max_load
= this_load
= total_load
= total_pwr
= 0;
2032 if (idle
== NOT_IDLE
)
2033 load_idx
= sd
->busy_idx
;
2034 else if (idle
== NEWLY_IDLE
)
2035 load_idx
= sd
->newidle_idx
;
2037 load_idx
= sd
->idle_idx
;
2044 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2046 /* Tally up the load of all CPUs in the group */
2049 for_each_cpu_mask(i
, group
->cpumask
) {
2050 if (*sd_idle
&& !idle_cpu(i
))
2053 /* Bias balancing toward cpus of our domain */
2055 load
= __target_load(i
, load_idx
, idle
);
2057 load
= __source_load(i
, load_idx
, idle
);
2062 total_load
+= avg_load
;
2063 total_pwr
+= group
->cpu_power
;
2065 /* Adjust by relative CPU power of the group */
2066 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2069 this_load
= avg_load
;
2071 } else if (avg_load
> max_load
) {
2072 max_load
= avg_load
;
2075 group
= group
->next
;
2076 } while (group
!= sd
->groups
);
2078 if (!busiest
|| this_load
>= max_load
|| max_load
<= SCHED_LOAD_SCALE
)
2081 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2083 if (this_load
>= avg_load
||
2084 100*max_load
<= sd
->imbalance_pct
*this_load
)
2088 * We're trying to get all the cpus to the average_load, so we don't
2089 * want to push ourselves above the average load, nor do we wish to
2090 * reduce the max loaded cpu below the average load, as either of these
2091 * actions would just result in more rebalancing later, and ping-pong
2092 * tasks around. Thus we look for the minimum possible imbalance.
2093 * Negative imbalances (*we* are more loaded than anyone else) will
2094 * be counted as no imbalance for these purposes -- we can't fix that
2095 * by pulling tasks to us. Be careful of negative numbers as they'll
2096 * appear as very large values with unsigned longs.
2099 /* Don't want to pull so many tasks that a group would go idle */
2100 max_pull
= min(max_load
- avg_load
, max_load
- SCHED_LOAD_SCALE
);
2102 /* How much load to actually move to equalise the imbalance */
2103 *imbalance
= min(max_pull
* busiest
->cpu_power
,
2104 (avg_load
- this_load
) * this->cpu_power
)
2107 if (*imbalance
< SCHED_LOAD_SCALE
) {
2108 unsigned long pwr_now
= 0, pwr_move
= 0;
2111 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
2117 * OK, we don't have enough imbalance to justify moving tasks,
2118 * however we may be able to increase total CPU power used by
2122 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
2123 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
2124 pwr_now
/= SCHED_LOAD_SCALE
;
2126 /* Amount of load we'd subtract */
2127 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
2129 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
2132 /* Amount of load we'd add */
2133 if (max_load
*busiest
->cpu_power
<
2134 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
2135 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
2137 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
2138 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
2139 pwr_move
/= SCHED_LOAD_SCALE
;
2141 /* Move if we gain throughput */
2142 if (pwr_move
<= pwr_now
)
2149 /* Get rid of the scaling factor, rounding down as we divide */
2150 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
2160 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2162 static runqueue_t
*find_busiest_queue(struct sched_group
*group
,
2163 enum idle_type idle
)
2165 unsigned long load
, max_load
= 0;
2166 runqueue_t
*busiest
= NULL
;
2169 for_each_cpu_mask(i
, group
->cpumask
) {
2170 load
= __source_load(i
, 0, idle
);
2172 if (load
> max_load
) {
2174 busiest
= cpu_rq(i
);
2182 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2183 * so long as it is large enough.
2185 #define MAX_PINNED_INTERVAL 512
2188 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2189 * tasks if there is an imbalance.
2191 * Called with this_rq unlocked.
2193 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
2194 struct sched_domain
*sd
, enum idle_type idle
)
2196 struct sched_group
*group
;
2197 runqueue_t
*busiest
;
2198 unsigned long imbalance
;
2199 int nr_moved
, all_pinned
= 0;
2200 int active_balance
= 0;
2203 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2206 schedstat_inc(sd
, lb_cnt
[idle
]);
2208 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
);
2210 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2214 busiest
= find_busiest_queue(group
, idle
);
2216 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2220 BUG_ON(busiest
== this_rq
);
2222 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2225 if (busiest
->nr_running
> 1) {
2227 * Attempt to move tasks. If find_busiest_group has found
2228 * an imbalance but busiest->nr_running <= 1, the group is
2229 * still unbalanced. nr_moved simply stays zero, so it is
2230 * correctly treated as an imbalance.
2232 double_rq_lock(this_rq
, busiest
);
2233 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2234 imbalance
, sd
, idle
, &all_pinned
);
2235 double_rq_unlock(this_rq
, busiest
);
2237 /* All tasks on this runqueue were pinned by CPU affinity */
2238 if (unlikely(all_pinned
))
2243 schedstat_inc(sd
, lb_failed
[idle
]);
2244 sd
->nr_balance_failed
++;
2246 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2248 spin_lock(&busiest
->lock
);
2250 /* don't kick the migration_thread, if the curr
2251 * task on busiest cpu can't be moved to this_cpu
2253 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2254 spin_unlock(&busiest
->lock
);
2256 goto out_one_pinned
;
2259 if (!busiest
->active_balance
) {
2260 busiest
->active_balance
= 1;
2261 busiest
->push_cpu
= this_cpu
;
2264 spin_unlock(&busiest
->lock
);
2266 wake_up_process(busiest
->migration_thread
);
2269 * We've kicked active balancing, reset the failure
2272 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2275 sd
->nr_balance_failed
= 0;
2277 if (likely(!active_balance
)) {
2278 /* We were unbalanced, so reset the balancing interval */
2279 sd
->balance_interval
= sd
->min_interval
;
2282 * If we've begun active balancing, start to back off. This
2283 * case may not be covered by the all_pinned logic if there
2284 * is only 1 task on the busy runqueue (because we don't call
2287 if (sd
->balance_interval
< sd
->max_interval
)
2288 sd
->balance_interval
*= 2;
2291 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2296 schedstat_inc(sd
, lb_balanced
[idle
]);
2298 sd
->nr_balance_failed
= 0;
2301 /* tune up the balancing interval */
2302 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2303 (sd
->balance_interval
< sd
->max_interval
))
2304 sd
->balance_interval
*= 2;
2306 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2312 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2313 * tasks if there is an imbalance.
2315 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2316 * this_rq is locked.
2318 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2319 struct sched_domain
*sd
)
2321 struct sched_group
*group
;
2322 runqueue_t
*busiest
= NULL
;
2323 unsigned long imbalance
;
2327 if (sd
->flags
& SD_SHARE_CPUPOWER
)
2330 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2331 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
, &sd_idle
);
2333 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2337 busiest
= find_busiest_queue(group
, NEWLY_IDLE
);
2339 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2343 BUG_ON(busiest
== this_rq
);
2345 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2348 if (busiest
->nr_running
> 1) {
2349 /* Attempt to move tasks */
2350 double_lock_balance(this_rq
, busiest
);
2351 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2352 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2353 spin_unlock(&busiest
->lock
);
2357 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2358 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2361 sd
->nr_balance_failed
= 0;
2366 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2367 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2369 sd
->nr_balance_failed
= 0;
2374 * idle_balance is called by schedule() if this_cpu is about to become
2375 * idle. Attempts to pull tasks from other CPUs.
2377 static inline void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2379 struct sched_domain
*sd
;
2381 for_each_domain(this_cpu
, sd
) {
2382 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2383 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2384 /* We've pulled tasks over so stop searching */
2392 * active_load_balance is run by migration threads. It pushes running tasks
2393 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2394 * running on each physical CPU where possible, and avoids physical /
2395 * logical imbalances.
2397 * Called with busiest_rq locked.
2399 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2401 struct sched_domain
*sd
;
2402 runqueue_t
*target_rq
;
2403 int target_cpu
= busiest_rq
->push_cpu
;
2405 if (busiest_rq
->nr_running
<= 1)
2406 /* no task to move */
2409 target_rq
= cpu_rq(target_cpu
);
2412 * This condition is "impossible", if it occurs
2413 * we need to fix it. Originally reported by
2414 * Bjorn Helgaas on a 128-cpu setup.
2416 BUG_ON(busiest_rq
== target_rq
);
2418 /* move a task from busiest_rq to target_rq */
2419 double_lock_balance(busiest_rq
, target_rq
);
2421 /* Search for an sd spanning us and the target CPU. */
2422 for_each_domain(target_cpu
, sd
)
2423 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2424 cpu_isset(busiest_cpu
, sd
->span
))
2427 if (unlikely(sd
== NULL
))
2430 schedstat_inc(sd
, alb_cnt
);
2432 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1, sd
, SCHED_IDLE
, NULL
))
2433 schedstat_inc(sd
, alb_pushed
);
2435 schedstat_inc(sd
, alb_failed
);
2437 spin_unlock(&target_rq
->lock
);
2441 * rebalance_tick will get called every timer tick, on every CPU.
2443 * It checks each scheduling domain to see if it is due to be balanced,
2444 * and initiates a balancing operation if so.
2446 * Balancing parameters are set up in arch_init_sched_domains.
2449 /* Don't have all balancing operations going off at once */
2450 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2452 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2453 enum idle_type idle
)
2455 unsigned long old_load
, this_load
;
2456 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2457 struct sched_domain
*sd
;
2460 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2461 /* Update our load */
2462 for (i
= 0; i
< 3; i
++) {
2463 unsigned long new_load
= this_load
;
2465 old_load
= this_rq
->cpu_load
[i
];
2467 * Round up the averaging division if load is increasing. This
2468 * prevents us from getting stuck on 9 if the load is 10, for
2471 if (new_load
> old_load
)
2472 new_load
+= scale
-1;
2473 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2476 for_each_domain(this_cpu
, sd
) {
2477 unsigned long interval
;
2479 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2482 interval
= sd
->balance_interval
;
2483 if (idle
!= SCHED_IDLE
)
2484 interval
*= sd
->busy_factor
;
2486 /* scale ms to jiffies */
2487 interval
= msecs_to_jiffies(interval
);
2488 if (unlikely(!interval
))
2491 if (j
- sd
->last_balance
>= interval
) {
2492 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2494 * We've pulled tasks over so either we're no
2495 * longer idle, or one of our SMT siblings is
2500 sd
->last_balance
+= interval
;
2506 * on UP we do not need to balance between CPUs:
2508 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2511 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2516 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2519 #ifdef CONFIG_SCHED_SMT
2520 spin_lock(&rq
->lock
);
2522 * If an SMT sibling task has been put to sleep for priority
2523 * reasons reschedule the idle task to see if it can now run.
2525 if (rq
->nr_running
) {
2526 resched_task(rq
->idle
);
2529 spin_unlock(&rq
->lock
);
2534 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2536 EXPORT_PER_CPU_SYMBOL(kstat
);
2539 * This is called on clock ticks and on context switches.
2540 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2542 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2543 unsigned long long now
)
2545 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2546 p
->sched_time
+= now
- last
;
2550 * Return current->sched_time plus any more ns on the sched_clock
2551 * that have not yet been banked.
2553 unsigned long long current_sched_time(const task_t
*tsk
)
2555 unsigned long long ns
;
2556 unsigned long flags
;
2557 local_irq_save(flags
);
2558 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2559 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2560 local_irq_restore(flags
);
2565 * We place interactive tasks back into the active array, if possible.
2567 * To guarantee that this does not starve expired tasks we ignore the
2568 * interactivity of a task if the first expired task had to wait more
2569 * than a 'reasonable' amount of time. This deadline timeout is
2570 * load-dependent, as the frequency of array switched decreases with
2571 * increasing number of running tasks. We also ignore the interactivity
2572 * if a better static_prio task has expired:
2574 #define EXPIRED_STARVING(rq) \
2575 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2576 (jiffies - (rq)->expired_timestamp >= \
2577 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2578 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2581 * Account user cpu time to a process.
2582 * @p: the process that the cpu time gets accounted to
2583 * @hardirq_offset: the offset to subtract from hardirq_count()
2584 * @cputime: the cpu time spent in user space since the last update
2586 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2588 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2591 p
->utime
= cputime_add(p
->utime
, cputime
);
2593 /* Add user time to cpustat. */
2594 tmp
= cputime_to_cputime64(cputime
);
2595 if (TASK_NICE(p
) > 0)
2596 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2598 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2602 * Account system cpu time to a process.
2603 * @p: the process that the cpu time gets accounted to
2604 * @hardirq_offset: the offset to subtract from hardirq_count()
2605 * @cputime: the cpu time spent in kernel space since the last update
2607 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2610 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2611 runqueue_t
*rq
= this_rq();
2614 p
->stime
= cputime_add(p
->stime
, cputime
);
2616 /* Add system time to cpustat. */
2617 tmp
= cputime_to_cputime64(cputime
);
2618 if (hardirq_count() - hardirq_offset
)
2619 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2620 else if (softirq_count())
2621 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2622 else if (p
!= rq
->idle
)
2623 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2624 else if (atomic_read(&rq
->nr_iowait
) > 0)
2625 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2627 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2628 /* Account for system time used */
2629 acct_update_integrals(p
);
2633 * Account for involuntary wait time.
2634 * @p: the process from which the cpu time has been stolen
2635 * @steal: the cpu time spent in involuntary wait
2637 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2639 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2640 cputime64_t tmp
= cputime_to_cputime64(steal
);
2641 runqueue_t
*rq
= this_rq();
2643 if (p
== rq
->idle
) {
2644 p
->stime
= cputime_add(p
->stime
, steal
);
2645 if (atomic_read(&rq
->nr_iowait
) > 0)
2646 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2648 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2650 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2654 * This function gets called by the timer code, with HZ frequency.
2655 * We call it with interrupts disabled.
2657 * It also gets called by the fork code, when changing the parent's
2660 void scheduler_tick(void)
2662 int cpu
= smp_processor_id();
2663 runqueue_t
*rq
= this_rq();
2664 task_t
*p
= current
;
2665 unsigned long long now
= sched_clock();
2667 update_cpu_clock(p
, rq
, now
);
2669 rq
->timestamp_last_tick
= now
;
2671 if (p
== rq
->idle
) {
2672 if (wake_priority_sleeper(rq
))
2674 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2678 /* Task might have expired already, but not scheduled off yet */
2679 if (p
->array
!= rq
->active
) {
2680 set_tsk_need_resched(p
);
2683 spin_lock(&rq
->lock
);
2685 * The task was running during this tick - update the
2686 * time slice counter. Note: we do not update a thread's
2687 * priority until it either goes to sleep or uses up its
2688 * timeslice. This makes it possible for interactive tasks
2689 * to use up their timeslices at their highest priority levels.
2693 * RR tasks need a special form of timeslice management.
2694 * FIFO tasks have no timeslices.
2696 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2697 p
->time_slice
= task_timeslice(p
);
2698 p
->first_time_slice
= 0;
2699 set_tsk_need_resched(p
);
2701 /* put it at the end of the queue: */
2702 requeue_task(p
, rq
->active
);
2706 if (!--p
->time_slice
) {
2707 dequeue_task(p
, rq
->active
);
2708 set_tsk_need_resched(p
);
2709 p
->prio
= effective_prio(p
);
2710 p
->time_slice
= task_timeslice(p
);
2711 p
->first_time_slice
= 0;
2713 if (!rq
->expired_timestamp
)
2714 rq
->expired_timestamp
= jiffies
;
2715 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2716 enqueue_task(p
, rq
->expired
);
2717 if (p
->static_prio
< rq
->best_expired_prio
)
2718 rq
->best_expired_prio
= p
->static_prio
;
2720 enqueue_task(p
, rq
->active
);
2723 * Prevent a too long timeslice allowing a task to monopolize
2724 * the CPU. We do this by splitting up the timeslice into
2727 * Note: this does not mean the task's timeslices expire or
2728 * get lost in any way, they just might be preempted by
2729 * another task of equal priority. (one with higher
2730 * priority would have preempted this task already.) We
2731 * requeue this task to the end of the list on this priority
2732 * level, which is in essence a round-robin of tasks with
2735 * This only applies to tasks in the interactive
2736 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2738 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2739 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2740 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2741 (p
->array
== rq
->active
)) {
2743 requeue_task(p
, rq
->active
);
2744 set_tsk_need_resched(p
);
2748 spin_unlock(&rq
->lock
);
2750 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2753 #ifdef CONFIG_SCHED_SMT
2754 static inline void wakeup_busy_runqueue(runqueue_t
*rq
)
2756 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
2757 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
2758 resched_task(rq
->idle
);
2761 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2763 struct sched_domain
*tmp
, *sd
= NULL
;
2764 cpumask_t sibling_map
;
2767 for_each_domain(this_cpu
, tmp
)
2768 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2775 * Unlock the current runqueue because we have to lock in
2776 * CPU order to avoid deadlocks. Caller knows that we might
2777 * unlock. We keep IRQs disabled.
2779 spin_unlock(&this_rq
->lock
);
2781 sibling_map
= sd
->span
;
2783 for_each_cpu_mask(i
, sibling_map
)
2784 spin_lock(&cpu_rq(i
)->lock
);
2786 * We clear this CPU from the mask. This both simplifies the
2787 * inner loop and keps this_rq locked when we exit:
2789 cpu_clear(this_cpu
, sibling_map
);
2791 for_each_cpu_mask(i
, sibling_map
) {
2792 runqueue_t
*smt_rq
= cpu_rq(i
);
2794 wakeup_busy_runqueue(smt_rq
);
2797 for_each_cpu_mask(i
, sibling_map
)
2798 spin_unlock(&cpu_rq(i
)->lock
);
2800 * We exit with this_cpu's rq still held and IRQs
2806 * number of 'lost' timeslices this task wont be able to fully
2807 * utilize, if another task runs on a sibling. This models the
2808 * slowdown effect of other tasks running on siblings:
2810 static inline unsigned long smt_slice(task_t
*p
, struct sched_domain
*sd
)
2812 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
2815 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2817 struct sched_domain
*tmp
, *sd
= NULL
;
2818 cpumask_t sibling_map
;
2819 prio_array_t
*array
;
2823 for_each_domain(this_cpu
, tmp
)
2824 if (tmp
->flags
& SD_SHARE_CPUPOWER
)
2831 * The same locking rules and details apply as for
2832 * wake_sleeping_dependent():
2834 spin_unlock(&this_rq
->lock
);
2835 sibling_map
= sd
->span
;
2836 for_each_cpu_mask(i
, sibling_map
)
2837 spin_lock(&cpu_rq(i
)->lock
);
2838 cpu_clear(this_cpu
, sibling_map
);
2841 * Establish next task to be run - it might have gone away because
2842 * we released the runqueue lock above:
2844 if (!this_rq
->nr_running
)
2846 array
= this_rq
->active
;
2847 if (!array
->nr_active
)
2848 array
= this_rq
->expired
;
2849 BUG_ON(!array
->nr_active
);
2851 p
= list_entry(array
->queue
[sched_find_first_bit(array
->bitmap
)].next
,
2854 for_each_cpu_mask(i
, sibling_map
) {
2855 runqueue_t
*smt_rq
= cpu_rq(i
);
2856 task_t
*smt_curr
= smt_rq
->curr
;
2858 /* Kernel threads do not participate in dependent sleeping */
2859 if (!p
->mm
|| !smt_curr
->mm
|| rt_task(p
))
2860 goto check_smt_task
;
2863 * If a user task with lower static priority than the
2864 * running task on the SMT sibling is trying to schedule,
2865 * delay it till there is proportionately less timeslice
2866 * left of the sibling task to prevent a lower priority
2867 * task from using an unfair proportion of the
2868 * physical cpu's resources. -ck
2870 if (rt_task(smt_curr
)) {
2872 * With real time tasks we run non-rt tasks only
2873 * per_cpu_gain% of the time.
2875 if ((jiffies
% DEF_TIMESLICE
) >
2876 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2879 if (smt_curr
->static_prio
< p
->static_prio
&&
2880 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2881 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
2885 if ((!smt_curr
->mm
&& smt_curr
!= smt_rq
->idle
) ||
2889 wakeup_busy_runqueue(smt_rq
);
2894 * Reschedule a lower priority task on the SMT sibling for
2895 * it to be put to sleep, or wake it up if it has been put to
2896 * sleep for priority reasons to see if it should run now.
2899 if ((jiffies
% DEF_TIMESLICE
) >
2900 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2901 resched_task(smt_curr
);
2903 if (TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2904 smt_slice(p
, sd
) > task_timeslice(smt_curr
))
2905 resched_task(smt_curr
);
2907 wakeup_busy_runqueue(smt_rq
);
2911 for_each_cpu_mask(i
, sibling_map
)
2912 spin_unlock(&cpu_rq(i
)->lock
);
2916 static inline void wake_sleeping_dependent(int this_cpu
, runqueue_t
*this_rq
)
2920 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
)
2926 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2928 void fastcall
add_preempt_count(int val
)
2933 BUG_ON((preempt_count() < 0));
2934 preempt_count() += val
;
2936 * Spinlock count overflowing soon?
2938 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2940 EXPORT_SYMBOL(add_preempt_count
);
2942 void fastcall
sub_preempt_count(int val
)
2947 BUG_ON(val
> preempt_count());
2949 * Is the spinlock portion underflowing?
2951 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2952 preempt_count() -= val
;
2954 EXPORT_SYMBOL(sub_preempt_count
);
2959 * schedule() is the main scheduler function.
2961 asmlinkage
void __sched
schedule(void)
2964 task_t
*prev
, *next
;
2966 prio_array_t
*array
;
2967 struct list_head
*queue
;
2968 unsigned long long now
;
2969 unsigned long run_time
;
2970 int cpu
, idx
, new_prio
;
2973 * Test if we are atomic. Since do_exit() needs to call into
2974 * schedule() atomically, we ignore that path for now.
2975 * Otherwise, whine if we are scheduling when we should not be.
2977 if (likely(!current
->exit_state
)) {
2978 if (unlikely(in_atomic())) {
2979 printk(KERN_ERR
"scheduling while atomic: "
2981 current
->comm
, preempt_count(), current
->pid
);
2985 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2990 release_kernel_lock(prev
);
2991 need_resched_nonpreemptible
:
2995 * The idle thread is not allowed to schedule!
2996 * Remove this check after it has been exercised a bit.
2998 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2999 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
3003 schedstat_inc(rq
, sched_cnt
);
3004 now
= sched_clock();
3005 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
3006 run_time
= now
- prev
->timestamp
;
3007 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
3010 run_time
= NS_MAX_SLEEP_AVG
;
3013 * Tasks charged proportionately less run_time at high sleep_avg to
3014 * delay them losing their interactive status
3016 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
3018 spin_lock_irq(&rq
->lock
);
3020 if (unlikely(prev
->flags
& PF_DEAD
))
3021 prev
->state
= EXIT_DEAD
;
3023 switch_count
= &prev
->nivcsw
;
3024 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3025 switch_count
= &prev
->nvcsw
;
3026 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3027 unlikely(signal_pending(prev
))))
3028 prev
->state
= TASK_RUNNING
;
3030 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
3031 rq
->nr_uninterruptible
++;
3032 deactivate_task(prev
, rq
);
3036 cpu
= smp_processor_id();
3037 if (unlikely(!rq
->nr_running
)) {
3039 idle_balance(cpu
, rq
);
3040 if (!rq
->nr_running
) {
3042 rq
->expired_timestamp
= 0;
3043 wake_sleeping_dependent(cpu
, rq
);
3045 * wake_sleeping_dependent() might have released
3046 * the runqueue, so break out if we got new
3049 if (!rq
->nr_running
)
3053 if (dependent_sleeper(cpu
, rq
)) {
3058 * dependent_sleeper() releases and reacquires the runqueue
3059 * lock, hence go into the idle loop if the rq went
3062 if (unlikely(!rq
->nr_running
))
3067 if (unlikely(!array
->nr_active
)) {
3069 * Switch the active and expired arrays.
3071 schedstat_inc(rq
, sched_switch
);
3072 rq
->active
= rq
->expired
;
3073 rq
->expired
= array
;
3075 rq
->expired_timestamp
= 0;
3076 rq
->best_expired_prio
= MAX_PRIO
;
3079 idx
= sched_find_first_bit(array
->bitmap
);
3080 queue
= array
->queue
+ idx
;
3081 next
= list_entry(queue
->next
, task_t
, run_list
);
3083 if (!rt_task(next
) && next
->activated
> 0) {
3084 unsigned long long delta
= now
- next
->timestamp
;
3085 if (unlikely((long long)(now
- next
->timestamp
) < 0))
3088 if (next
->activated
== 1)
3089 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
3091 array
= next
->array
;
3092 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
3094 if (unlikely(next
->prio
!= new_prio
)) {
3095 dequeue_task(next
, array
);
3096 next
->prio
= new_prio
;
3097 enqueue_task(next
, array
);
3099 requeue_task(next
, array
);
3101 next
->activated
= 0;
3103 if (next
== rq
->idle
)
3104 schedstat_inc(rq
, sched_goidle
);
3106 prefetch_stack(next
);
3107 clear_tsk_need_resched(prev
);
3108 rcu_qsctr_inc(task_cpu(prev
));
3110 update_cpu_clock(prev
, rq
, now
);
3112 prev
->sleep_avg
-= run_time
;
3113 if ((long)prev
->sleep_avg
<= 0)
3114 prev
->sleep_avg
= 0;
3115 prev
->timestamp
= prev
->last_ran
= now
;
3117 sched_info_switch(prev
, next
);
3118 if (likely(prev
!= next
)) {
3119 next
->timestamp
= now
;
3124 prepare_task_switch(rq
, next
);
3125 prev
= context_switch(rq
, prev
, next
);
3128 * this_rq must be evaluated again because prev may have moved
3129 * CPUs since it called schedule(), thus the 'rq' on its stack
3130 * frame will be invalid.
3132 finish_task_switch(this_rq(), prev
);
3134 spin_unlock_irq(&rq
->lock
);
3137 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3138 goto need_resched_nonpreemptible
;
3139 preempt_enable_no_resched();
3140 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3144 EXPORT_SYMBOL(schedule
);
3146 #ifdef CONFIG_PREEMPT
3148 * this is is the entry point to schedule() from in-kernel preemption
3149 * off of preempt_enable. Kernel preemptions off return from interrupt
3150 * occur there and call schedule directly.
3152 asmlinkage
void __sched
preempt_schedule(void)
3154 struct thread_info
*ti
= current_thread_info();
3155 #ifdef CONFIG_PREEMPT_BKL
3156 struct task_struct
*task
= current
;
3157 int saved_lock_depth
;
3160 * If there is a non-zero preempt_count or interrupts are disabled,
3161 * we do not want to preempt the current task. Just return..
3163 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
3167 add_preempt_count(PREEMPT_ACTIVE
);
3169 * We keep the big kernel semaphore locked, but we
3170 * clear ->lock_depth so that schedule() doesnt
3171 * auto-release the semaphore:
3173 #ifdef CONFIG_PREEMPT_BKL
3174 saved_lock_depth
= task
->lock_depth
;
3175 task
->lock_depth
= -1;
3178 #ifdef CONFIG_PREEMPT_BKL
3179 task
->lock_depth
= saved_lock_depth
;
3181 sub_preempt_count(PREEMPT_ACTIVE
);
3183 /* we could miss a preemption opportunity between schedule and now */
3185 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3189 EXPORT_SYMBOL(preempt_schedule
);
3192 * this is is the entry point to schedule() from kernel preemption
3193 * off of irq context.
3194 * Note, that this is called and return with irqs disabled. This will
3195 * protect us against recursive calling from irq.
3197 asmlinkage
void __sched
preempt_schedule_irq(void)
3199 struct thread_info
*ti
= current_thread_info();
3200 #ifdef CONFIG_PREEMPT_BKL
3201 struct task_struct
*task
= current
;
3202 int saved_lock_depth
;
3204 /* Catch callers which need to be fixed*/
3205 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3208 add_preempt_count(PREEMPT_ACTIVE
);
3210 * We keep the big kernel semaphore locked, but we
3211 * clear ->lock_depth so that schedule() doesnt
3212 * auto-release the semaphore:
3214 #ifdef CONFIG_PREEMPT_BKL
3215 saved_lock_depth
= task
->lock_depth
;
3216 task
->lock_depth
= -1;
3220 local_irq_disable();
3221 #ifdef CONFIG_PREEMPT_BKL
3222 task
->lock_depth
= saved_lock_depth
;
3224 sub_preempt_count(PREEMPT_ACTIVE
);
3226 /* we could miss a preemption opportunity between schedule and now */
3228 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3232 #endif /* CONFIG_PREEMPT */
3234 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3237 task_t
*p
= curr
->private;
3238 return try_to_wake_up(p
, mode
, sync
);
3241 EXPORT_SYMBOL(default_wake_function
);
3244 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3245 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3246 * number) then we wake all the non-exclusive tasks and one exclusive task.
3248 * There are circumstances in which we can try to wake a task which has already
3249 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3250 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3252 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3253 int nr_exclusive
, int sync
, void *key
)
3255 struct list_head
*tmp
, *next
;
3257 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3260 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3261 flags
= curr
->flags
;
3262 if (curr
->func(curr
, mode
, sync
, key
) &&
3263 (flags
& WQ_FLAG_EXCLUSIVE
) &&
3270 * __wake_up - wake up threads blocked on a waitqueue.
3272 * @mode: which threads
3273 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3274 * @key: is directly passed to the wakeup function
3276 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3277 int nr_exclusive
, void *key
)
3279 unsigned long flags
;
3281 spin_lock_irqsave(&q
->lock
, flags
);
3282 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3283 spin_unlock_irqrestore(&q
->lock
, flags
);
3286 EXPORT_SYMBOL(__wake_up
);
3289 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3291 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3293 __wake_up_common(q
, mode
, 1, 0, NULL
);
3297 * __wake_up_sync - wake up threads blocked on a waitqueue.
3299 * @mode: which threads
3300 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3302 * The sync wakeup differs that the waker knows that it will schedule
3303 * away soon, so while the target thread will be woken up, it will not
3304 * be migrated to another CPU - ie. the two threads are 'synchronized'
3305 * with each other. This can prevent needless bouncing between CPUs.
3307 * On UP it can prevent extra preemption.
3310 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3312 unsigned long flags
;
3318 if (unlikely(!nr_exclusive
))
3321 spin_lock_irqsave(&q
->lock
, flags
);
3322 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3323 spin_unlock_irqrestore(&q
->lock
, flags
);
3325 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3327 void fastcall
complete(struct completion
*x
)
3329 unsigned long flags
;
3331 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3333 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3335 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3337 EXPORT_SYMBOL(complete
);
3339 void fastcall
complete_all(struct completion
*x
)
3341 unsigned long flags
;
3343 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3344 x
->done
+= UINT_MAX
/2;
3345 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3347 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3349 EXPORT_SYMBOL(complete_all
);
3351 void fastcall __sched
wait_for_completion(struct completion
*x
)
3354 spin_lock_irq(&x
->wait
.lock
);
3356 DECLARE_WAITQUEUE(wait
, current
);
3358 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3359 __add_wait_queue_tail(&x
->wait
, &wait
);
3361 __set_current_state(TASK_UNINTERRUPTIBLE
);
3362 spin_unlock_irq(&x
->wait
.lock
);
3364 spin_lock_irq(&x
->wait
.lock
);
3366 __remove_wait_queue(&x
->wait
, &wait
);
3369 spin_unlock_irq(&x
->wait
.lock
);
3371 EXPORT_SYMBOL(wait_for_completion
);
3373 unsigned long fastcall __sched
3374 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3378 spin_lock_irq(&x
->wait
.lock
);
3380 DECLARE_WAITQUEUE(wait
, current
);
3382 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3383 __add_wait_queue_tail(&x
->wait
, &wait
);
3385 __set_current_state(TASK_UNINTERRUPTIBLE
);
3386 spin_unlock_irq(&x
->wait
.lock
);
3387 timeout
= schedule_timeout(timeout
);
3388 spin_lock_irq(&x
->wait
.lock
);
3390 __remove_wait_queue(&x
->wait
, &wait
);
3394 __remove_wait_queue(&x
->wait
, &wait
);
3398 spin_unlock_irq(&x
->wait
.lock
);
3401 EXPORT_SYMBOL(wait_for_completion_timeout
);
3403 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3409 spin_lock_irq(&x
->wait
.lock
);
3411 DECLARE_WAITQUEUE(wait
, current
);
3413 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3414 __add_wait_queue_tail(&x
->wait
, &wait
);
3416 if (signal_pending(current
)) {
3418 __remove_wait_queue(&x
->wait
, &wait
);
3421 __set_current_state(TASK_INTERRUPTIBLE
);
3422 spin_unlock_irq(&x
->wait
.lock
);
3424 spin_lock_irq(&x
->wait
.lock
);
3426 __remove_wait_queue(&x
->wait
, &wait
);
3430 spin_unlock_irq(&x
->wait
.lock
);
3434 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3436 unsigned long fastcall __sched
3437 wait_for_completion_interruptible_timeout(struct completion
*x
,
3438 unsigned long timeout
)
3442 spin_lock_irq(&x
->wait
.lock
);
3444 DECLARE_WAITQUEUE(wait
, current
);
3446 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3447 __add_wait_queue_tail(&x
->wait
, &wait
);
3449 if (signal_pending(current
)) {
3450 timeout
= -ERESTARTSYS
;
3451 __remove_wait_queue(&x
->wait
, &wait
);
3454 __set_current_state(TASK_INTERRUPTIBLE
);
3455 spin_unlock_irq(&x
->wait
.lock
);
3456 timeout
= schedule_timeout(timeout
);
3457 spin_lock_irq(&x
->wait
.lock
);
3459 __remove_wait_queue(&x
->wait
, &wait
);
3463 __remove_wait_queue(&x
->wait
, &wait
);
3467 spin_unlock_irq(&x
->wait
.lock
);
3470 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3473 #define SLEEP_ON_VAR \
3474 unsigned long flags; \
3475 wait_queue_t wait; \
3476 init_waitqueue_entry(&wait, current);
3478 #define SLEEP_ON_HEAD \
3479 spin_lock_irqsave(&q->lock,flags); \
3480 __add_wait_queue(q, &wait); \
3481 spin_unlock(&q->lock);
3483 #define SLEEP_ON_TAIL \
3484 spin_lock_irq(&q->lock); \
3485 __remove_wait_queue(q, &wait); \
3486 spin_unlock_irqrestore(&q->lock, flags);
3488 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3492 current
->state
= TASK_INTERRUPTIBLE
;
3499 EXPORT_SYMBOL(interruptible_sleep_on
);
3501 long fastcall __sched
3502 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3506 current
->state
= TASK_INTERRUPTIBLE
;
3509 timeout
= schedule_timeout(timeout
);
3515 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3517 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3521 current
->state
= TASK_UNINTERRUPTIBLE
;
3528 EXPORT_SYMBOL(sleep_on
);
3530 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3534 current
->state
= TASK_UNINTERRUPTIBLE
;
3537 timeout
= schedule_timeout(timeout
);
3543 EXPORT_SYMBOL(sleep_on_timeout
);
3545 void set_user_nice(task_t
*p
, long nice
)
3547 unsigned long flags
;
3548 prio_array_t
*array
;
3550 int old_prio
, new_prio
, delta
;
3552 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3555 * We have to be careful, if called from sys_setpriority(),
3556 * the task might be in the middle of scheduling on another CPU.
3558 rq
= task_rq_lock(p
, &flags
);
3560 * The RT priorities are set via sched_setscheduler(), but we still
3561 * allow the 'normal' nice value to be set - but as expected
3562 * it wont have any effect on scheduling until the task is
3566 p
->static_prio
= NICE_TO_PRIO(nice
);
3571 dequeue_task(p
, array
);
3572 dec_prio_bias(rq
, p
->static_prio
);
3576 new_prio
= NICE_TO_PRIO(nice
);
3577 delta
= new_prio
- old_prio
;
3578 p
->static_prio
= NICE_TO_PRIO(nice
);
3582 enqueue_task(p
, array
);
3583 inc_prio_bias(rq
, p
->static_prio
);
3585 * If the task increased its priority or is running and
3586 * lowered its priority, then reschedule its CPU:
3588 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3589 resched_task(rq
->curr
);
3592 task_rq_unlock(rq
, &flags
);
3595 EXPORT_SYMBOL(set_user_nice
);
3598 * can_nice - check if a task can reduce its nice value
3602 int can_nice(const task_t
*p
, const int nice
)
3604 /* convert nice value [19,-20] to rlimit style value [1,40] */
3605 int nice_rlim
= 20 - nice
;
3606 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3607 capable(CAP_SYS_NICE
));
3610 #ifdef __ARCH_WANT_SYS_NICE
3613 * sys_nice - change the priority of the current process.
3614 * @increment: priority increment
3616 * sys_setpriority is a more generic, but much slower function that
3617 * does similar things.
3619 asmlinkage
long sys_nice(int increment
)
3625 * Setpriority might change our priority at the same moment.
3626 * We don't have to worry. Conceptually one call occurs first
3627 * and we have a single winner.
3629 if (increment
< -40)
3634 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3640 if (increment
< 0 && !can_nice(current
, nice
))
3643 retval
= security_task_setnice(current
, nice
);
3647 set_user_nice(current
, nice
);
3654 * task_prio - return the priority value of a given task.
3655 * @p: the task in question.
3657 * This is the priority value as seen by users in /proc.
3658 * RT tasks are offset by -200. Normal tasks are centered
3659 * around 0, value goes from -16 to +15.
3661 int task_prio(const task_t
*p
)
3663 return p
->prio
- MAX_RT_PRIO
;
3667 * task_nice - return the nice value of a given task.
3668 * @p: the task in question.
3670 int task_nice(const task_t
*p
)
3672 return TASK_NICE(p
);
3674 EXPORT_SYMBOL_GPL(task_nice
);
3677 * idle_cpu - is a given cpu idle currently?
3678 * @cpu: the processor in question.
3680 int idle_cpu(int cpu
)
3682 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3686 * idle_task - return the idle task for a given cpu.
3687 * @cpu: the processor in question.
3689 task_t
*idle_task(int cpu
)
3691 return cpu_rq(cpu
)->idle
;
3695 * find_process_by_pid - find a process with a matching PID value.
3696 * @pid: the pid in question.
3698 static inline task_t
*find_process_by_pid(pid_t pid
)
3700 return pid
? find_task_by_pid(pid
) : current
;
3703 /* Actually do priority change: must hold rq lock. */
3704 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3708 p
->rt_priority
= prio
;
3709 if (policy
!= SCHED_NORMAL
)
3710 p
->prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
3712 p
->prio
= p
->static_prio
;
3716 * sched_setscheduler - change the scheduling policy and/or RT priority of
3718 * @p: the task in question.
3719 * @policy: new policy.
3720 * @param: structure containing the new RT priority.
3722 int sched_setscheduler(struct task_struct
*p
, int policy
,
3723 struct sched_param
*param
)
3726 int oldprio
, oldpolicy
= -1;
3727 prio_array_t
*array
;
3728 unsigned long flags
;
3732 /* double check policy once rq lock held */
3734 policy
= oldpolicy
= p
->policy
;
3735 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3736 policy
!= SCHED_NORMAL
)
3739 * Valid priorities for SCHED_FIFO and SCHED_RR are
3740 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3742 if (param
->sched_priority
< 0 ||
3743 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3744 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3746 if ((policy
== SCHED_NORMAL
) != (param
->sched_priority
== 0))
3750 * Allow unprivileged RT tasks to decrease priority:
3752 if (!capable(CAP_SYS_NICE
)) {
3753 /* can't change policy */
3754 if (policy
!= p
->policy
&&
3755 !p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3757 /* can't increase priority */
3758 if (policy
!= SCHED_NORMAL
&&
3759 param
->sched_priority
> p
->rt_priority
&&
3760 param
->sched_priority
>
3761 p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3763 /* can't change other user's priorities */
3764 if ((current
->euid
!= p
->euid
) &&
3765 (current
->euid
!= p
->uid
))
3769 retval
= security_task_setscheduler(p
, policy
, param
);
3773 * To be able to change p->policy safely, the apropriate
3774 * runqueue lock must be held.
3776 rq
= task_rq_lock(p
, &flags
);
3777 /* recheck policy now with rq lock held */
3778 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3779 policy
= oldpolicy
= -1;
3780 task_rq_unlock(rq
, &flags
);
3785 deactivate_task(p
, rq
);
3787 __setscheduler(p
, policy
, param
->sched_priority
);
3789 __activate_task(p
, rq
);
3791 * Reschedule if we are currently running on this runqueue and
3792 * our priority decreased, or if we are not currently running on
3793 * this runqueue and our priority is higher than the current's
3795 if (task_running(rq
, p
)) {
3796 if (p
->prio
> oldprio
)
3797 resched_task(rq
->curr
);
3798 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3799 resched_task(rq
->curr
);
3801 task_rq_unlock(rq
, &flags
);
3804 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3807 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3810 struct sched_param lparam
;
3811 struct task_struct
*p
;
3813 if (!param
|| pid
< 0)
3815 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3817 read_lock_irq(&tasklist_lock
);
3818 p
= find_process_by_pid(pid
);
3820 read_unlock_irq(&tasklist_lock
);
3823 retval
= sched_setscheduler(p
, policy
, &lparam
);
3824 read_unlock_irq(&tasklist_lock
);
3829 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3830 * @pid: the pid in question.
3831 * @policy: new policy.
3832 * @param: structure containing the new RT priority.
3834 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3835 struct sched_param __user
*param
)
3837 return do_sched_setscheduler(pid
, policy
, param
);
3841 * sys_sched_setparam - set/change the RT priority of a thread
3842 * @pid: the pid in question.
3843 * @param: structure containing the new RT priority.
3845 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3847 return do_sched_setscheduler(pid
, -1, param
);
3851 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3852 * @pid: the pid in question.
3854 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3856 int retval
= -EINVAL
;
3863 read_lock(&tasklist_lock
);
3864 p
= find_process_by_pid(pid
);
3866 retval
= security_task_getscheduler(p
);
3870 read_unlock(&tasklist_lock
);
3877 * sys_sched_getscheduler - get the RT priority of a thread
3878 * @pid: the pid in question.
3879 * @param: structure containing the RT priority.
3881 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3883 struct sched_param lp
;
3884 int retval
= -EINVAL
;
3887 if (!param
|| pid
< 0)
3890 read_lock(&tasklist_lock
);
3891 p
= find_process_by_pid(pid
);
3896 retval
= security_task_getscheduler(p
);
3900 lp
.sched_priority
= p
->rt_priority
;
3901 read_unlock(&tasklist_lock
);
3904 * This one might sleep, we cannot do it with a spinlock held ...
3906 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3912 read_unlock(&tasklist_lock
);
3916 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3920 cpumask_t cpus_allowed
;
3923 read_lock(&tasklist_lock
);
3925 p
= find_process_by_pid(pid
);
3927 read_unlock(&tasklist_lock
);
3928 unlock_cpu_hotplug();
3933 * It is not safe to call set_cpus_allowed with the
3934 * tasklist_lock held. We will bump the task_struct's
3935 * usage count and then drop tasklist_lock.
3938 read_unlock(&tasklist_lock
);
3941 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3942 !capable(CAP_SYS_NICE
))
3945 cpus_allowed
= cpuset_cpus_allowed(p
);
3946 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3947 retval
= set_cpus_allowed(p
, new_mask
);
3951 unlock_cpu_hotplug();
3955 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3956 cpumask_t
*new_mask
)
3958 if (len
< sizeof(cpumask_t
)) {
3959 memset(new_mask
, 0, sizeof(cpumask_t
));
3960 } else if (len
> sizeof(cpumask_t
)) {
3961 len
= sizeof(cpumask_t
);
3963 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3967 * sys_sched_setaffinity - set the cpu affinity of a process
3968 * @pid: pid of the process
3969 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3970 * @user_mask_ptr: user-space pointer to the new cpu mask
3972 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3973 unsigned long __user
*user_mask_ptr
)
3978 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3982 return sched_setaffinity(pid
, new_mask
);
3986 * Represents all cpu's present in the system
3987 * In systems capable of hotplug, this map could dynamically grow
3988 * as new cpu's are detected in the system via any platform specific
3989 * method, such as ACPI for e.g.
3992 cpumask_t cpu_present_map __read_mostly
;
3993 EXPORT_SYMBOL(cpu_present_map
);
3996 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
3997 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4000 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4006 read_lock(&tasklist_lock
);
4009 p
= find_process_by_pid(pid
);
4014 cpus_and(*mask
, p
->cpus_allowed
, cpu_possible_map
);
4017 read_unlock(&tasklist_lock
);
4018 unlock_cpu_hotplug();
4026 * sys_sched_getaffinity - get the cpu affinity of a process
4027 * @pid: pid of the process
4028 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4029 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4031 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4032 unsigned long __user
*user_mask_ptr
)
4037 if (len
< sizeof(cpumask_t
))
4040 ret
= sched_getaffinity(pid
, &mask
);
4044 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4047 return sizeof(cpumask_t
);
4051 * sys_sched_yield - yield the current processor to other threads.
4053 * this function yields the current CPU by moving the calling thread
4054 * to the expired array. If there are no other threads running on this
4055 * CPU then this function will return.
4057 asmlinkage
long sys_sched_yield(void)
4059 runqueue_t
*rq
= this_rq_lock();
4060 prio_array_t
*array
= current
->array
;
4061 prio_array_t
*target
= rq
->expired
;
4063 schedstat_inc(rq
, yld_cnt
);
4065 * We implement yielding by moving the task into the expired
4068 * (special rule: RT tasks will just roundrobin in the active
4071 if (rt_task(current
))
4072 target
= rq
->active
;
4074 if (array
->nr_active
== 1) {
4075 schedstat_inc(rq
, yld_act_empty
);
4076 if (!rq
->expired
->nr_active
)
4077 schedstat_inc(rq
, yld_both_empty
);
4078 } else if (!rq
->expired
->nr_active
)
4079 schedstat_inc(rq
, yld_exp_empty
);
4081 if (array
!= target
) {
4082 dequeue_task(current
, array
);
4083 enqueue_task(current
, target
);
4086 * requeue_task is cheaper so perform that if possible.
4088 requeue_task(current
, array
);
4091 * Since we are going to call schedule() anyway, there's
4092 * no need to preempt or enable interrupts:
4094 __release(rq
->lock
);
4095 _raw_spin_unlock(&rq
->lock
);
4096 preempt_enable_no_resched();
4103 static inline void __cond_resched(void)
4106 * The BKS might be reacquired before we have dropped
4107 * PREEMPT_ACTIVE, which could trigger a second
4108 * cond_resched() call.
4110 if (unlikely(preempt_count()))
4113 add_preempt_count(PREEMPT_ACTIVE
);
4115 sub_preempt_count(PREEMPT_ACTIVE
);
4116 } while (need_resched());
4119 int __sched
cond_resched(void)
4121 if (need_resched()) {
4128 EXPORT_SYMBOL(cond_resched
);
4131 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4132 * call schedule, and on return reacquire the lock.
4134 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4135 * operations here to prevent schedule() from being called twice (once via
4136 * spin_unlock(), once by hand).
4138 int cond_resched_lock(spinlock_t
*lock
)
4142 if (need_lockbreak(lock
)) {
4148 if (need_resched()) {
4149 _raw_spin_unlock(lock
);
4150 preempt_enable_no_resched();
4158 EXPORT_SYMBOL(cond_resched_lock
);
4160 int __sched
cond_resched_softirq(void)
4162 BUG_ON(!in_softirq());
4164 if (need_resched()) {
4165 __local_bh_enable();
4173 EXPORT_SYMBOL(cond_resched_softirq
);
4177 * yield - yield the current processor to other threads.
4179 * this is a shortcut for kernel-space yielding - it marks the
4180 * thread runnable and calls sys_sched_yield().
4182 void __sched
yield(void)
4184 set_current_state(TASK_RUNNING
);
4188 EXPORT_SYMBOL(yield
);
4191 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4192 * that process accounting knows that this is a task in IO wait state.
4194 * But don't do that if it is a deliberate, throttling IO wait (this task
4195 * has set its backing_dev_info: the queue against which it should throttle)
4197 void __sched
io_schedule(void)
4199 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4201 atomic_inc(&rq
->nr_iowait
);
4203 atomic_dec(&rq
->nr_iowait
);
4206 EXPORT_SYMBOL(io_schedule
);
4208 long __sched
io_schedule_timeout(long timeout
)
4210 struct runqueue
*rq
= &per_cpu(runqueues
, raw_smp_processor_id());
4213 atomic_inc(&rq
->nr_iowait
);
4214 ret
= schedule_timeout(timeout
);
4215 atomic_dec(&rq
->nr_iowait
);
4220 * sys_sched_get_priority_max - return maximum RT priority.
4221 * @policy: scheduling class.
4223 * this syscall returns the maximum rt_priority that can be used
4224 * by a given scheduling class.
4226 asmlinkage
long sys_sched_get_priority_max(int policy
)
4233 ret
= MAX_USER_RT_PRIO
-1;
4243 * sys_sched_get_priority_min - return minimum RT priority.
4244 * @policy: scheduling class.
4246 * this syscall returns the minimum rt_priority that can be used
4247 * by a given scheduling class.
4249 asmlinkage
long sys_sched_get_priority_min(int policy
)
4265 * sys_sched_rr_get_interval - return the default timeslice of a process.
4266 * @pid: pid of the process.
4267 * @interval: userspace pointer to the timeslice value.
4269 * this syscall writes the default timeslice value of a given process
4270 * into the user-space timespec buffer. A value of '0' means infinity.
4273 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4275 int retval
= -EINVAL
;
4283 read_lock(&tasklist_lock
);
4284 p
= find_process_by_pid(pid
);
4288 retval
= security_task_getscheduler(p
);
4292 jiffies_to_timespec(p
->policy
& SCHED_FIFO
?
4293 0 : task_timeslice(p
), &t
);
4294 read_unlock(&tasklist_lock
);
4295 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4299 read_unlock(&tasklist_lock
);
4303 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4305 if (list_empty(&p
->children
)) return NULL
;
4306 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4309 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4311 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
4312 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4315 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4317 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
4318 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4321 static void show_task(task_t
*p
)
4325 unsigned long free
= 0;
4326 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
4328 printk("%-13.13s ", p
->comm
);
4329 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4330 if (state
< ARRAY_SIZE(stat_nam
))
4331 printk(stat_nam
[state
]);
4334 #if (BITS_PER_LONG == 32)
4335 if (state
== TASK_RUNNING
)
4336 printk(" running ");
4338 printk(" %08lX ", thread_saved_pc(p
));
4340 if (state
== TASK_RUNNING
)
4341 printk(" running task ");
4343 printk(" %016lx ", thread_saved_pc(p
));
4345 #ifdef CONFIG_DEBUG_STACK_USAGE
4347 unsigned long *n
= end_of_stack(p
);
4350 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4353 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4354 if ((relative
= eldest_child(p
)))
4355 printk("%5d ", relative
->pid
);
4358 if ((relative
= younger_sibling(p
)))
4359 printk("%7d", relative
->pid
);
4362 if ((relative
= older_sibling(p
)))
4363 printk(" %5d", relative
->pid
);
4367 printk(" (L-TLB)\n");
4369 printk(" (NOTLB)\n");
4371 if (state
!= TASK_RUNNING
)
4372 show_stack(p
, NULL
);
4375 void show_state(void)
4379 #if (BITS_PER_LONG == 32)
4382 printk(" task PC pid father child younger older\n");
4386 printk(" task PC pid father child younger older\n");
4388 read_lock(&tasklist_lock
);
4389 do_each_thread(g
, p
) {
4391 * reset the NMI-timeout, listing all files on a slow
4392 * console might take alot of time:
4394 touch_nmi_watchdog();
4396 } while_each_thread(g
, p
);
4398 read_unlock(&tasklist_lock
);
4399 mutex_debug_show_all_locks();
4403 * init_idle - set up an idle thread for a given CPU
4404 * @idle: task in question
4405 * @cpu: cpu the idle task belongs to
4407 * NOTE: this function does not set the idle thread's NEED_RESCHED
4408 * flag, to make booting more robust.
4410 void __devinit
init_idle(task_t
*idle
, int cpu
)
4412 runqueue_t
*rq
= cpu_rq(cpu
);
4413 unsigned long flags
;
4415 idle
->sleep_avg
= 0;
4417 idle
->prio
= MAX_PRIO
;
4418 idle
->state
= TASK_RUNNING
;
4419 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4420 set_task_cpu(idle
, cpu
);
4422 spin_lock_irqsave(&rq
->lock
, flags
);
4423 rq
->curr
= rq
->idle
= idle
;
4424 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4427 spin_unlock_irqrestore(&rq
->lock
, flags
);
4429 /* Set the preempt count _outside_ the spinlocks! */
4430 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4431 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4433 task_thread_info(idle
)->preempt_count
= 0;
4438 * In a system that switches off the HZ timer nohz_cpu_mask
4439 * indicates which cpus entered this state. This is used
4440 * in the rcu update to wait only for active cpus. For system
4441 * which do not switch off the HZ timer nohz_cpu_mask should
4442 * always be CPU_MASK_NONE.
4444 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4448 * This is how migration works:
4450 * 1) we queue a migration_req_t structure in the source CPU's
4451 * runqueue and wake up that CPU's migration thread.
4452 * 2) we down() the locked semaphore => thread blocks.
4453 * 3) migration thread wakes up (implicitly it forces the migrated
4454 * thread off the CPU)
4455 * 4) it gets the migration request and checks whether the migrated
4456 * task is still in the wrong runqueue.
4457 * 5) if it's in the wrong runqueue then the migration thread removes
4458 * it and puts it into the right queue.
4459 * 6) migration thread up()s the semaphore.
4460 * 7) we wake up and the migration is done.
4464 * Change a given task's CPU affinity. Migrate the thread to a
4465 * proper CPU and schedule it away if the CPU it's executing on
4466 * is removed from the allowed bitmask.
4468 * NOTE: the caller must have a valid reference to the task, the
4469 * task must not exit() & deallocate itself prematurely. The
4470 * call is not atomic; no spinlocks may be held.
4472 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4474 unsigned long flags
;
4476 migration_req_t req
;
4479 rq
= task_rq_lock(p
, &flags
);
4480 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4485 p
->cpus_allowed
= new_mask
;
4486 /* Can the task run on the task's current CPU? If so, we're done */
4487 if (cpu_isset(task_cpu(p
), new_mask
))
4490 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4491 /* Need help from migration thread: drop lock and wait. */
4492 task_rq_unlock(rq
, &flags
);
4493 wake_up_process(rq
->migration_thread
);
4494 wait_for_completion(&req
.done
);
4495 tlb_migrate_finish(p
->mm
);
4499 task_rq_unlock(rq
, &flags
);
4503 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4506 * Move (not current) task off this cpu, onto dest cpu. We're doing
4507 * this because either it can't run here any more (set_cpus_allowed()
4508 * away from this CPU, or CPU going down), or because we're
4509 * attempting to rebalance this task on exec (sched_exec).
4511 * So we race with normal scheduler movements, but that's OK, as long
4512 * as the task is no longer on this CPU.
4514 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4516 runqueue_t
*rq_dest
, *rq_src
;
4518 if (unlikely(cpu_is_offline(dest_cpu
)))
4521 rq_src
= cpu_rq(src_cpu
);
4522 rq_dest
= cpu_rq(dest_cpu
);
4524 double_rq_lock(rq_src
, rq_dest
);
4525 /* Already moved. */
4526 if (task_cpu(p
) != src_cpu
)
4528 /* Affinity changed (again). */
4529 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4532 set_task_cpu(p
, dest_cpu
);
4535 * Sync timestamp with rq_dest's before activating.
4536 * The same thing could be achieved by doing this step
4537 * afterwards, and pretending it was a local activate.
4538 * This way is cleaner and logically correct.
4540 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4541 + rq_dest
->timestamp_last_tick
;
4542 deactivate_task(p
, rq_src
);
4543 activate_task(p
, rq_dest
, 0);
4544 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4545 resched_task(rq_dest
->curr
);
4549 double_rq_unlock(rq_src
, rq_dest
);
4553 * migration_thread - this is a highprio system thread that performs
4554 * thread migration by bumping thread off CPU then 'pushing' onto
4557 static int migration_thread(void *data
)
4560 int cpu
= (long)data
;
4563 BUG_ON(rq
->migration_thread
!= current
);
4565 set_current_state(TASK_INTERRUPTIBLE
);
4566 while (!kthread_should_stop()) {
4567 struct list_head
*head
;
4568 migration_req_t
*req
;
4572 spin_lock_irq(&rq
->lock
);
4574 if (cpu_is_offline(cpu
)) {
4575 spin_unlock_irq(&rq
->lock
);
4579 if (rq
->active_balance
) {
4580 active_load_balance(rq
, cpu
);
4581 rq
->active_balance
= 0;
4584 head
= &rq
->migration_queue
;
4586 if (list_empty(head
)) {
4587 spin_unlock_irq(&rq
->lock
);
4589 set_current_state(TASK_INTERRUPTIBLE
);
4592 req
= list_entry(head
->next
, migration_req_t
, list
);
4593 list_del_init(head
->next
);
4595 spin_unlock(&rq
->lock
);
4596 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4599 complete(&req
->done
);
4601 __set_current_state(TASK_RUNNING
);
4605 /* Wait for kthread_stop */
4606 set_current_state(TASK_INTERRUPTIBLE
);
4607 while (!kthread_should_stop()) {
4609 set_current_state(TASK_INTERRUPTIBLE
);
4611 __set_current_state(TASK_RUNNING
);
4615 #ifdef CONFIG_HOTPLUG_CPU
4616 /* Figure out where task on dead CPU should go, use force if neccessary. */
4617 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4623 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4624 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4625 dest_cpu
= any_online_cpu(mask
);
4627 /* On any allowed CPU? */
4628 if (dest_cpu
== NR_CPUS
)
4629 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4631 /* No more Mr. Nice Guy. */
4632 if (dest_cpu
== NR_CPUS
) {
4633 cpus_setall(tsk
->cpus_allowed
);
4634 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4637 * Don't tell them about moving exiting tasks or
4638 * kernel threads (both mm NULL), since they never
4641 if (tsk
->mm
&& printk_ratelimit())
4642 printk(KERN_INFO
"process %d (%s) no "
4643 "longer affine to cpu%d\n",
4644 tsk
->pid
, tsk
->comm
, dead_cpu
);
4646 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4650 * While a dead CPU has no uninterruptible tasks queued at this point,
4651 * it might still have a nonzero ->nr_uninterruptible counter, because
4652 * for performance reasons the counter is not stricly tracking tasks to
4653 * their home CPUs. So we just add the counter to another CPU's counter,
4654 * to keep the global sum constant after CPU-down:
4656 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4658 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4659 unsigned long flags
;
4661 local_irq_save(flags
);
4662 double_rq_lock(rq_src
, rq_dest
);
4663 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4664 rq_src
->nr_uninterruptible
= 0;
4665 double_rq_unlock(rq_src
, rq_dest
);
4666 local_irq_restore(flags
);
4669 /* Run through task list and migrate tasks from the dead cpu. */
4670 static void migrate_live_tasks(int src_cpu
)
4672 struct task_struct
*tsk
, *t
;
4674 write_lock_irq(&tasklist_lock
);
4676 do_each_thread(t
, tsk
) {
4680 if (task_cpu(tsk
) == src_cpu
)
4681 move_task_off_dead_cpu(src_cpu
, tsk
);
4682 } while_each_thread(t
, tsk
);
4684 write_unlock_irq(&tasklist_lock
);
4687 /* Schedules idle task to be the next runnable task on current CPU.
4688 * It does so by boosting its priority to highest possible and adding it to
4689 * the _front_ of runqueue. Used by CPU offline code.
4691 void sched_idle_next(void)
4693 int cpu
= smp_processor_id();
4694 runqueue_t
*rq
= this_rq();
4695 struct task_struct
*p
= rq
->idle
;
4696 unsigned long flags
;
4698 /* cpu has to be offline */
4699 BUG_ON(cpu_online(cpu
));
4701 /* Strictly not necessary since rest of the CPUs are stopped by now
4702 * and interrupts disabled on current cpu.
4704 spin_lock_irqsave(&rq
->lock
, flags
);
4706 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4707 /* Add idle task to _front_ of it's priority queue */
4708 __activate_idle_task(p
, rq
);
4710 spin_unlock_irqrestore(&rq
->lock
, flags
);
4713 /* Ensures that the idle task is using init_mm right before its cpu goes
4716 void idle_task_exit(void)
4718 struct mm_struct
*mm
= current
->active_mm
;
4720 BUG_ON(cpu_online(smp_processor_id()));
4723 switch_mm(mm
, &init_mm
, current
);
4727 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4729 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4731 /* Must be exiting, otherwise would be on tasklist. */
4732 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4734 /* Cannot have done final schedule yet: would have vanished. */
4735 BUG_ON(tsk
->flags
& PF_DEAD
);
4737 get_task_struct(tsk
);
4740 * Drop lock around migration; if someone else moves it,
4741 * that's OK. No task can be added to this CPU, so iteration is
4744 spin_unlock_irq(&rq
->lock
);
4745 move_task_off_dead_cpu(dead_cpu
, tsk
);
4746 spin_lock_irq(&rq
->lock
);
4748 put_task_struct(tsk
);
4751 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4752 static void migrate_dead_tasks(unsigned int dead_cpu
)
4755 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4757 for (arr
= 0; arr
< 2; arr
++) {
4758 for (i
= 0; i
< MAX_PRIO
; i
++) {
4759 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4760 while (!list_empty(list
))
4761 migrate_dead(dead_cpu
,
4762 list_entry(list
->next
, task_t
,
4767 #endif /* CONFIG_HOTPLUG_CPU */
4770 * migration_call - callback that gets triggered when a CPU is added.
4771 * Here we can start up the necessary migration thread for the new CPU.
4773 static int migration_call(struct notifier_block
*nfb
, unsigned long action
,
4776 int cpu
= (long)hcpu
;
4777 struct task_struct
*p
;
4778 struct runqueue
*rq
;
4779 unsigned long flags
;
4782 case CPU_UP_PREPARE
:
4783 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4786 p
->flags
|= PF_NOFREEZE
;
4787 kthread_bind(p
, cpu
);
4788 /* Must be high prio: stop_machine expects to yield to it. */
4789 rq
= task_rq_lock(p
, &flags
);
4790 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4791 task_rq_unlock(rq
, &flags
);
4792 cpu_rq(cpu
)->migration_thread
= p
;
4795 /* Strictly unneccessary, as first user will wake it. */
4796 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4798 #ifdef CONFIG_HOTPLUG_CPU
4799 case CPU_UP_CANCELED
:
4800 /* Unbind it from offline cpu so it can run. Fall thru. */
4801 kthread_bind(cpu_rq(cpu
)->migration_thread
,
4802 any_online_cpu(cpu_online_map
));
4803 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4804 cpu_rq(cpu
)->migration_thread
= NULL
;
4807 migrate_live_tasks(cpu
);
4809 kthread_stop(rq
->migration_thread
);
4810 rq
->migration_thread
= NULL
;
4811 /* Idle task back to normal (off runqueue, low prio) */
4812 rq
= task_rq_lock(rq
->idle
, &flags
);
4813 deactivate_task(rq
->idle
, rq
);
4814 rq
->idle
->static_prio
= MAX_PRIO
;
4815 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4816 migrate_dead_tasks(cpu
);
4817 task_rq_unlock(rq
, &flags
);
4818 migrate_nr_uninterruptible(rq
);
4819 BUG_ON(rq
->nr_running
!= 0);
4821 /* No need to migrate the tasks: it was best-effort if
4822 * they didn't do lock_cpu_hotplug(). Just wake up
4823 * the requestors. */
4824 spin_lock_irq(&rq
->lock
);
4825 while (!list_empty(&rq
->migration_queue
)) {
4826 migration_req_t
*req
;
4827 req
= list_entry(rq
->migration_queue
.next
,
4828 migration_req_t
, list
);
4829 list_del_init(&req
->list
);
4830 complete(&req
->done
);
4832 spin_unlock_irq(&rq
->lock
);
4839 /* Register at highest priority so that task migration (migrate_all_tasks)
4840 * happens before everything else.
4842 static struct notifier_block __devinitdata migration_notifier
= {
4843 .notifier_call
= migration_call
,
4847 int __init
migration_init(void)
4849 void *cpu
= (void *)(long)smp_processor_id();
4850 /* Start one for boot CPU. */
4851 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4852 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4853 register_cpu_notifier(&migration_notifier
);
4859 #undef SCHED_DOMAIN_DEBUG
4860 #ifdef SCHED_DOMAIN_DEBUG
4861 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4866 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4870 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4875 struct sched_group
*group
= sd
->groups
;
4876 cpumask_t groupmask
;
4878 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4879 cpus_clear(groupmask
);
4882 for (i
= 0; i
< level
+ 1; i
++)
4884 printk("domain %d: ", level
);
4886 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4887 printk("does not load-balance\n");
4889 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4893 printk("span %s\n", str
);
4895 if (!cpu_isset(cpu
, sd
->span
))
4896 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4897 if (!cpu_isset(cpu
, group
->cpumask
))
4898 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4901 for (i
= 0; i
< level
+ 2; i
++)
4907 printk(KERN_ERR
"ERROR: group is NULL\n");
4911 if (!group
->cpu_power
) {
4913 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4916 if (!cpus_weight(group
->cpumask
)) {
4918 printk(KERN_ERR
"ERROR: empty group\n");
4921 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4923 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4926 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4928 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4931 group
= group
->next
;
4932 } while (group
!= sd
->groups
);
4935 if (!cpus_equal(sd
->span
, groupmask
))
4936 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4942 if (!cpus_subset(groupmask
, sd
->span
))
4943 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4949 #define sched_domain_debug(sd, cpu) {}
4952 static int sd_degenerate(struct sched_domain
*sd
)
4954 if (cpus_weight(sd
->span
) == 1)
4957 /* Following flags need at least 2 groups */
4958 if (sd
->flags
& (SD_LOAD_BALANCE
|
4959 SD_BALANCE_NEWIDLE
|
4962 if (sd
->groups
!= sd
->groups
->next
)
4966 /* Following flags don't use groups */
4967 if (sd
->flags
& (SD_WAKE_IDLE
|
4975 static int sd_parent_degenerate(struct sched_domain
*sd
,
4976 struct sched_domain
*parent
)
4978 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
4980 if (sd_degenerate(parent
))
4983 if (!cpus_equal(sd
->span
, parent
->span
))
4986 /* Does parent contain flags not in child? */
4987 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
4988 if (cflags
& SD_WAKE_AFFINE
)
4989 pflags
&= ~SD_WAKE_BALANCE
;
4990 /* Flags needing groups don't count if only 1 group in parent */
4991 if (parent
->groups
== parent
->groups
->next
) {
4992 pflags
&= ~(SD_LOAD_BALANCE
|
4993 SD_BALANCE_NEWIDLE
|
4997 if (~cflags
& pflags
)
5004 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5005 * hold the hotplug lock.
5007 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5009 runqueue_t
*rq
= cpu_rq(cpu
);
5010 struct sched_domain
*tmp
;
5012 /* Remove the sched domains which do not contribute to scheduling. */
5013 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5014 struct sched_domain
*parent
= tmp
->parent
;
5017 if (sd_parent_degenerate(tmp
, parent
))
5018 tmp
->parent
= parent
->parent
;
5021 if (sd
&& sd_degenerate(sd
))
5024 sched_domain_debug(sd
, cpu
);
5026 rcu_assign_pointer(rq
->sd
, sd
);
5029 /* cpus with isolated domains */
5030 static cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
5032 /* Setup the mask of cpus configured for isolated domains */
5033 static int __init
isolated_cpu_setup(char *str
)
5035 int ints
[NR_CPUS
], i
;
5037 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5038 cpus_clear(cpu_isolated_map
);
5039 for (i
= 1; i
<= ints
[0]; i
++)
5040 if (ints
[i
] < NR_CPUS
)
5041 cpu_set(ints
[i
], cpu_isolated_map
);
5045 __setup ("isolcpus=", isolated_cpu_setup
);
5048 * init_sched_build_groups takes an array of groups, the cpumask we wish
5049 * to span, and a pointer to a function which identifies what group a CPU
5050 * belongs to. The return value of group_fn must be a valid index into the
5051 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
5052 * keep track of groups covered with a cpumask_t).
5054 * init_sched_build_groups will build a circular linked list of the groups
5055 * covered by the given span, and will set each group's ->cpumask correctly,
5056 * and ->cpu_power to 0.
5058 static void init_sched_build_groups(struct sched_group groups
[], cpumask_t span
,
5059 int (*group_fn
)(int cpu
))
5061 struct sched_group
*first
= NULL
, *last
= NULL
;
5062 cpumask_t covered
= CPU_MASK_NONE
;
5065 for_each_cpu_mask(i
, span
) {
5066 int group
= group_fn(i
);
5067 struct sched_group
*sg
= &groups
[group
];
5070 if (cpu_isset(i
, covered
))
5073 sg
->cpumask
= CPU_MASK_NONE
;
5076 for_each_cpu_mask(j
, span
) {
5077 if (group_fn(j
) != group
)
5080 cpu_set(j
, covered
);
5081 cpu_set(j
, sg
->cpumask
);
5092 #define SD_NODES_PER_DOMAIN 16
5095 * Self-tuning task migration cost measurement between source and target CPUs.
5097 * This is done by measuring the cost of manipulating buffers of varying
5098 * sizes. For a given buffer-size here are the steps that are taken:
5100 * 1) the source CPU reads+dirties a shared buffer
5101 * 2) the target CPU reads+dirties the same shared buffer
5103 * We measure how long they take, in the following 4 scenarios:
5105 * - source: CPU1, target: CPU2 | cost1
5106 * - source: CPU2, target: CPU1 | cost2
5107 * - source: CPU1, target: CPU1 | cost3
5108 * - source: CPU2, target: CPU2 | cost4
5110 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5111 * the cost of migration.
5113 * We then start off from a small buffer-size and iterate up to larger
5114 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5115 * doing a maximum search for the cost. (The maximum cost for a migration
5116 * normally occurs when the working set size is around the effective cache
5119 #define SEARCH_SCOPE 2
5120 #define MIN_CACHE_SIZE (64*1024U)
5121 #define DEFAULT_CACHE_SIZE (5*1024*1024U)
5122 #define ITERATIONS 2
5123 #define SIZE_THRESH 130
5124 #define COST_THRESH 130
5127 * The migration cost is a function of 'domain distance'. Domain
5128 * distance is the number of steps a CPU has to iterate down its
5129 * domain tree to share a domain with the other CPU. The farther
5130 * two CPUs are from each other, the larger the distance gets.
5132 * Note that we use the distance only to cache measurement results,
5133 * the distance value is not used numerically otherwise. When two
5134 * CPUs have the same distance it is assumed that the migration
5135 * cost is the same. (this is a simplification but quite practical)
5137 #define MAX_DOMAIN_DISTANCE 32
5139 static unsigned long long migration_cost
[MAX_DOMAIN_DISTANCE
] =
5140 { [ 0 ... MAX_DOMAIN_DISTANCE
-1 ] = -1LL };
5143 * Allow override of migration cost - in units of microseconds.
5144 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5145 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5147 static int __init
migration_cost_setup(char *str
)
5149 int ints
[MAX_DOMAIN_DISTANCE
+1], i
;
5151 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5153 printk("#ints: %d\n", ints
[0]);
5154 for (i
= 1; i
<= ints
[0]; i
++) {
5155 migration_cost
[i
-1] = (unsigned long long)ints
[i
]*1000;
5156 printk("migration_cost[%d]: %Ld\n", i
-1, migration_cost
[i
-1]);
5161 __setup ("migration_cost=", migration_cost_setup
);
5164 * Global multiplier (divisor) for migration-cutoff values,
5165 * in percentiles. E.g. use a value of 150 to get 1.5 times
5166 * longer cache-hot cutoff times.
5168 * (We scale it from 100 to 128 to long long handling easier.)
5171 #define MIGRATION_FACTOR_SCALE 128
5173 static unsigned int migration_factor
= MIGRATION_FACTOR_SCALE
;
5175 static int __init
setup_migration_factor(char *str
)
5177 get_option(&str
, &migration_factor
);
5178 migration_factor
= migration_factor
* MIGRATION_FACTOR_SCALE
/ 100;
5182 __setup("migration_factor=", setup_migration_factor
);
5185 * Estimated distance of two CPUs, measured via the number of domains
5186 * we have to pass for the two CPUs to be in the same span:
5188 static unsigned long domain_distance(int cpu1
, int cpu2
)
5190 unsigned long distance
= 0;
5191 struct sched_domain
*sd
;
5193 for_each_domain(cpu1
, sd
) {
5194 WARN_ON(!cpu_isset(cpu1
, sd
->span
));
5195 if (cpu_isset(cpu2
, sd
->span
))
5199 if (distance
>= MAX_DOMAIN_DISTANCE
) {
5201 distance
= MAX_DOMAIN_DISTANCE
-1;
5207 static unsigned int migration_debug
;
5209 static int __init
setup_migration_debug(char *str
)
5211 get_option(&str
, &migration_debug
);
5215 __setup("migration_debug=", setup_migration_debug
);
5218 * Maximum cache-size that the scheduler should try to measure.
5219 * Architectures with larger caches should tune this up during
5220 * bootup. Gets used in the domain-setup code (i.e. during SMP
5223 unsigned int max_cache_size
;
5225 static int __init
setup_max_cache_size(char *str
)
5227 get_option(&str
, &max_cache_size
);
5231 __setup("max_cache_size=", setup_max_cache_size
);
5234 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5235 * is the operation that is timed, so we try to generate unpredictable
5236 * cachemisses that still end up filling the L2 cache:
5238 static void touch_cache(void *__cache
, unsigned long __size
)
5240 unsigned long size
= __size
/sizeof(long), chunk1
= size
/3,
5242 unsigned long *cache
= __cache
;
5245 for (i
= 0; i
< size
/6; i
+= 8) {
5248 case 1: cache
[size
-1-i
]++;
5249 case 2: cache
[chunk1
-i
]++;
5250 case 3: cache
[chunk1
+i
]++;
5251 case 4: cache
[chunk2
-i
]++;
5252 case 5: cache
[chunk2
+i
]++;
5258 * Measure the cache-cost of one task migration. Returns in units of nsec.
5260 static unsigned long long measure_one(void *cache
, unsigned long size
,
5261 int source
, int target
)
5263 cpumask_t mask
, saved_mask
;
5264 unsigned long long t0
, t1
, t2
, t3
, cost
;
5266 saved_mask
= current
->cpus_allowed
;
5269 * Flush source caches to RAM and invalidate them:
5274 * Migrate to the source CPU:
5276 mask
= cpumask_of_cpu(source
);
5277 set_cpus_allowed(current
, mask
);
5278 WARN_ON(smp_processor_id() != source
);
5281 * Dirty the working set:
5284 touch_cache(cache
, size
);
5288 * Migrate to the target CPU, dirty the L2 cache and access
5289 * the shared buffer. (which represents the working set
5290 * of a migrated task.)
5292 mask
= cpumask_of_cpu(target
);
5293 set_cpus_allowed(current
, mask
);
5294 WARN_ON(smp_processor_id() != target
);
5297 touch_cache(cache
, size
);
5300 cost
= t1
-t0
+ t3
-t2
;
5302 if (migration_debug
>= 2)
5303 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5304 source
, target
, t1
-t0
, t1
-t0
, t3
-t2
, cost
);
5306 * Flush target caches to RAM and invalidate them:
5310 set_cpus_allowed(current
, saved_mask
);
5316 * Measure a series of task migrations and return the average
5317 * result. Since this code runs early during bootup the system
5318 * is 'undisturbed' and the average latency makes sense.
5320 * The algorithm in essence auto-detects the relevant cache-size,
5321 * so it will properly detect different cachesizes for different
5322 * cache-hierarchies, depending on how the CPUs are connected.
5324 * Architectures can prime the upper limit of the search range via
5325 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5327 static unsigned long long
5328 measure_cost(int cpu1
, int cpu2
, void *cache
, unsigned int size
)
5330 unsigned long long cost1
, cost2
;
5334 * Measure the migration cost of 'size' bytes, over an
5335 * average of 10 runs:
5337 * (We perturb the cache size by a small (0..4k)
5338 * value to compensate size/alignment related artifacts.
5339 * We also subtract the cost of the operation done on
5345 * dry run, to make sure we start off cache-cold on cpu1,
5346 * and to get any vmalloc pagefaults in advance:
5348 measure_one(cache
, size
, cpu1
, cpu2
);
5349 for (i
= 0; i
< ITERATIONS
; i
++)
5350 cost1
+= measure_one(cache
, size
- i
*1024, cpu1
, cpu2
);
5352 measure_one(cache
, size
, cpu2
, cpu1
);
5353 for (i
= 0; i
< ITERATIONS
; i
++)
5354 cost1
+= measure_one(cache
, size
- i
*1024, cpu2
, cpu1
);
5357 * (We measure the non-migrating [cached] cost on both
5358 * cpu1 and cpu2, to handle CPUs with different speeds)
5362 measure_one(cache
, size
, cpu1
, cpu1
);
5363 for (i
= 0; i
< ITERATIONS
; i
++)
5364 cost2
+= measure_one(cache
, size
- i
*1024, cpu1
, cpu1
);
5366 measure_one(cache
, size
, cpu2
, cpu2
);
5367 for (i
= 0; i
< ITERATIONS
; i
++)
5368 cost2
+= measure_one(cache
, size
- i
*1024, cpu2
, cpu2
);
5371 * Get the per-iteration migration cost:
5373 do_div(cost1
, 2*ITERATIONS
);
5374 do_div(cost2
, 2*ITERATIONS
);
5376 return cost1
- cost2
;
5379 static unsigned long long measure_migration_cost(int cpu1
, int cpu2
)
5381 unsigned long long max_cost
= 0, fluct
= 0, avg_fluct
= 0;
5382 unsigned int max_size
, size
, size_found
= 0;
5383 long long cost
= 0, prev_cost
;
5387 * Search from max_cache_size*5 down to 64K - the real relevant
5388 * cachesize has to lie somewhere inbetween.
5390 if (max_cache_size
) {
5391 max_size
= max(max_cache_size
* SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5392 size
= max(max_cache_size
/ SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5395 * Since we have no estimation about the relevant
5398 max_size
= DEFAULT_CACHE_SIZE
* SEARCH_SCOPE
;
5399 size
= MIN_CACHE_SIZE
;
5402 if (!cpu_online(cpu1
) || !cpu_online(cpu2
)) {
5403 printk("cpu %d and %d not both online!\n", cpu1
, cpu2
);
5408 * Allocate the working set:
5410 cache
= vmalloc(max_size
);
5412 printk("could not vmalloc %d bytes for cache!\n", 2*max_size
);
5413 return 1000000; // return 1 msec on very small boxen
5416 while (size
<= max_size
) {
5418 cost
= measure_cost(cpu1
, cpu2
, cache
, size
);
5424 if (max_cost
< cost
) {
5430 * Calculate average fluctuation, we use this to prevent
5431 * noise from triggering an early break out of the loop:
5433 fluct
= abs(cost
- prev_cost
);
5434 avg_fluct
= (avg_fluct
+ fluct
)/2;
5436 if (migration_debug
)
5437 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): (%8Ld %8Ld)\n",
5439 (long)cost
/ 1000000,
5440 ((long)cost
/ 100000) % 10,
5441 (long)max_cost
/ 1000000,
5442 ((long)max_cost
/ 100000) % 10,
5443 domain_distance(cpu1
, cpu2
),
5447 * If we iterated at least 20% past the previous maximum,
5448 * and the cost has dropped by more than 20% already,
5449 * (taking fluctuations into account) then we assume to
5450 * have found the maximum and break out of the loop early:
5452 if (size_found
&& (size
*100 > size_found
*SIZE_THRESH
))
5453 if (cost
+avg_fluct
<= 0 ||
5454 max_cost
*100 > (cost
+avg_fluct
)*COST_THRESH
) {
5456 if (migration_debug
)
5457 printk("-> found max.\n");
5461 * Increase the cachesize in 5% steps:
5463 size
= size
* 20 / 19;
5466 if (migration_debug
)
5467 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
5468 cpu1
, cpu2
, size_found
, max_cost
);
5473 * A task is considered 'cache cold' if at least 2 times
5474 * the worst-case cost of migration has passed.
5476 * (this limit is only listened to if the load-balancing
5477 * situation is 'nice' - if there is a large imbalance we
5478 * ignore it for the sake of CPU utilization and
5479 * processing fairness.)
5481 return 2 * max_cost
* migration_factor
/ MIGRATION_FACTOR_SCALE
;
5484 static void calibrate_migration_costs(const cpumask_t
*cpu_map
)
5486 int cpu1
= -1, cpu2
= -1, cpu
, orig_cpu
= raw_smp_processor_id();
5487 unsigned long j0
, j1
, distance
, max_distance
= 0;
5488 struct sched_domain
*sd
;
5493 * First pass - calculate the cacheflush times:
5495 for_each_cpu_mask(cpu1
, *cpu_map
) {
5496 for_each_cpu_mask(cpu2
, *cpu_map
) {
5499 distance
= domain_distance(cpu1
, cpu2
);
5500 max_distance
= max(max_distance
, distance
);
5502 * No result cached yet?
5504 if (migration_cost
[distance
] == -1LL)
5505 migration_cost
[distance
] =
5506 measure_migration_cost(cpu1
, cpu2
);
5510 * Second pass - update the sched domain hierarchy with
5511 * the new cache-hot-time estimations:
5513 for_each_cpu_mask(cpu
, *cpu_map
) {
5515 for_each_domain(cpu
, sd
) {
5516 sd
->cache_hot_time
= migration_cost
[distance
];
5523 if (migration_debug
)
5524 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
5532 printk("migration_cost=");
5533 for (distance
= 0; distance
<= max_distance
; distance
++) {
5536 printk("%ld", (long)migration_cost
[distance
] / 1000);
5540 if (migration_debug
)
5541 printk("migration: %ld seconds\n", (j1
-j0
)/HZ
);
5544 * Move back to the original CPU. NUMA-Q gets confused
5545 * if we migrate to another quad during bootup.
5547 if (raw_smp_processor_id() != orig_cpu
) {
5548 cpumask_t mask
= cpumask_of_cpu(orig_cpu
),
5549 saved_mask
= current
->cpus_allowed
;
5551 set_cpus_allowed(current
, mask
);
5552 set_cpus_allowed(current
, saved_mask
);
5559 * find_next_best_node - find the next node to include in a sched_domain
5560 * @node: node whose sched_domain we're building
5561 * @used_nodes: nodes already in the sched_domain
5563 * Find the next node to include in a given scheduling domain. Simply
5564 * finds the closest node not already in the @used_nodes map.
5566 * Should use nodemask_t.
5568 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5570 int i
, n
, val
, min_val
, best_node
= 0;
5574 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5575 /* Start at @node */
5576 n
= (node
+ i
) % MAX_NUMNODES
;
5578 if (!nr_cpus_node(n
))
5581 /* Skip already used nodes */
5582 if (test_bit(n
, used_nodes
))
5585 /* Simple min distance search */
5586 val
= node_distance(node
, n
);
5588 if (val
< min_val
) {
5594 set_bit(best_node
, used_nodes
);
5599 * sched_domain_node_span - get a cpumask for a node's sched_domain
5600 * @node: node whose cpumask we're constructing
5601 * @size: number of nodes to include in this span
5603 * Given a node, construct a good cpumask for its sched_domain to span. It
5604 * should be one that prevents unnecessary balancing, but also spreads tasks
5607 static cpumask_t
sched_domain_node_span(int node
)
5610 cpumask_t span
, nodemask
;
5611 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5614 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5616 nodemask
= node_to_cpumask(node
);
5617 cpus_or(span
, span
, nodemask
);
5618 set_bit(node
, used_nodes
);
5620 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5621 int next_node
= find_next_best_node(node
, used_nodes
);
5622 nodemask
= node_to_cpumask(next_node
);
5623 cpus_or(span
, span
, nodemask
);
5631 * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
5632 * can switch it on easily if needed.
5634 #ifdef CONFIG_SCHED_SMT
5635 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5636 static struct sched_group sched_group_cpus
[NR_CPUS
];
5637 static int cpu_to_cpu_group(int cpu
)
5643 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5644 static struct sched_group sched_group_phys
[NR_CPUS
];
5645 static int cpu_to_phys_group(int cpu
)
5647 #ifdef CONFIG_SCHED_SMT
5648 return first_cpu(cpu_sibling_map
[cpu
]);
5656 * The init_sched_build_groups can't handle what we want to do with node
5657 * groups, so roll our own. Now each node has its own list of groups which
5658 * gets dynamically allocated.
5660 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5661 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5663 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5664 static struct sched_group
*sched_group_allnodes_bycpu
[NR_CPUS
];
5666 static int cpu_to_allnodes_group(int cpu
)
5668 return cpu_to_node(cpu
);
5673 * Build sched domains for a given set of cpus and attach the sched domains
5674 * to the individual cpus
5676 void build_sched_domains(const cpumask_t
*cpu_map
)
5680 struct sched_group
**sched_group_nodes
= NULL
;
5681 struct sched_group
*sched_group_allnodes
= NULL
;
5684 * Allocate the per-node list of sched groups
5686 sched_group_nodes
= kmalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
5688 if (!sched_group_nodes
) {
5689 printk(KERN_WARNING
"Can not alloc sched group node list\n");
5692 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
5696 * Set up domains for cpus specified by the cpu_map.
5698 for_each_cpu_mask(i
, *cpu_map
) {
5700 struct sched_domain
*sd
= NULL
, *p
;
5701 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
5703 cpus_and(nodemask
, nodemask
, *cpu_map
);
5706 if (cpus_weight(*cpu_map
)
5707 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
5708 if (!sched_group_allnodes
) {
5709 sched_group_allnodes
5710 = kmalloc(sizeof(struct sched_group
)
5713 if (!sched_group_allnodes
) {
5715 "Can not alloc allnodes sched group\n");
5718 sched_group_allnodes_bycpu
[i
]
5719 = sched_group_allnodes
;
5721 sd
= &per_cpu(allnodes_domains
, i
);
5722 *sd
= SD_ALLNODES_INIT
;
5723 sd
->span
= *cpu_map
;
5724 group
= cpu_to_allnodes_group(i
);
5725 sd
->groups
= &sched_group_allnodes
[group
];
5730 sd
= &per_cpu(node_domains
, i
);
5732 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
5734 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5738 sd
= &per_cpu(phys_domains
, i
);
5739 group
= cpu_to_phys_group(i
);
5741 sd
->span
= nodemask
;
5743 sd
->groups
= &sched_group_phys
[group
];
5745 #ifdef CONFIG_SCHED_SMT
5747 sd
= &per_cpu(cpu_domains
, i
);
5748 group
= cpu_to_cpu_group(i
);
5749 *sd
= SD_SIBLING_INIT
;
5750 sd
->span
= cpu_sibling_map
[i
];
5751 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5753 sd
->groups
= &sched_group_cpus
[group
];
5757 #ifdef CONFIG_SCHED_SMT
5758 /* Set up CPU (sibling) groups */
5759 for_each_cpu_mask(i
, *cpu_map
) {
5760 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
5761 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
5762 if (i
!= first_cpu(this_sibling_map
))
5765 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
5770 /* Set up physical groups */
5771 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5772 cpumask_t nodemask
= node_to_cpumask(i
);
5774 cpus_and(nodemask
, nodemask
, *cpu_map
);
5775 if (cpus_empty(nodemask
))
5778 init_sched_build_groups(sched_group_phys
, nodemask
,
5779 &cpu_to_phys_group
);
5783 /* Set up node groups */
5784 if (sched_group_allnodes
)
5785 init_sched_build_groups(sched_group_allnodes
, *cpu_map
,
5786 &cpu_to_allnodes_group
);
5788 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5789 /* Set up node groups */
5790 struct sched_group
*sg
, *prev
;
5791 cpumask_t nodemask
= node_to_cpumask(i
);
5792 cpumask_t domainspan
;
5793 cpumask_t covered
= CPU_MASK_NONE
;
5796 cpus_and(nodemask
, nodemask
, *cpu_map
);
5797 if (cpus_empty(nodemask
)) {
5798 sched_group_nodes
[i
] = NULL
;
5802 domainspan
= sched_domain_node_span(i
);
5803 cpus_and(domainspan
, domainspan
, *cpu_map
);
5805 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5806 sched_group_nodes
[i
] = sg
;
5807 for_each_cpu_mask(j
, nodemask
) {
5808 struct sched_domain
*sd
;
5809 sd
= &per_cpu(node_domains
, j
);
5811 if (sd
->groups
== NULL
) {
5812 /* Turn off balancing if we have no groups */
5818 "Can not alloc domain group for node %d\n", i
);
5822 sg
->cpumask
= nodemask
;
5823 cpus_or(covered
, covered
, nodemask
);
5826 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
5827 cpumask_t tmp
, notcovered
;
5828 int n
= (i
+ j
) % MAX_NUMNODES
;
5830 cpus_complement(notcovered
, covered
);
5831 cpus_and(tmp
, notcovered
, *cpu_map
);
5832 cpus_and(tmp
, tmp
, domainspan
);
5833 if (cpus_empty(tmp
))
5836 nodemask
= node_to_cpumask(n
);
5837 cpus_and(tmp
, tmp
, nodemask
);
5838 if (cpus_empty(tmp
))
5841 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5844 "Can not alloc domain group for node %d\n", j
);
5849 cpus_or(covered
, covered
, tmp
);
5853 prev
->next
= sched_group_nodes
[i
];
5857 /* Calculate CPU power for physical packages and nodes */
5858 for_each_cpu_mask(i
, *cpu_map
) {
5860 struct sched_domain
*sd
;
5861 #ifdef CONFIG_SCHED_SMT
5862 sd
= &per_cpu(cpu_domains
, i
);
5863 power
= SCHED_LOAD_SCALE
;
5864 sd
->groups
->cpu_power
= power
;
5867 sd
= &per_cpu(phys_domains
, i
);
5868 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5869 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5870 sd
->groups
->cpu_power
= power
;
5873 sd
= &per_cpu(allnodes_domains
, i
);
5875 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5876 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5877 sd
->groups
->cpu_power
= power
;
5883 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5884 struct sched_group
*sg
= sched_group_nodes
[i
];
5890 for_each_cpu_mask(j
, sg
->cpumask
) {
5891 struct sched_domain
*sd
;
5894 sd
= &per_cpu(phys_domains
, j
);
5895 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5897 * Only add "power" once for each
5902 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5903 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5905 sg
->cpu_power
+= power
;
5908 if (sg
!= sched_group_nodes
[i
])
5913 /* Attach the domains */
5914 for_each_cpu_mask(i
, *cpu_map
) {
5915 struct sched_domain
*sd
;
5916 #ifdef CONFIG_SCHED_SMT
5917 sd
= &per_cpu(cpu_domains
, i
);
5919 sd
= &per_cpu(phys_domains
, i
);
5921 cpu_attach_domain(sd
, i
);
5924 * Tune cache-hot values:
5926 calibrate_migration_costs(cpu_map
);
5929 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5931 static void arch_init_sched_domains(const cpumask_t
*cpu_map
)
5933 cpumask_t cpu_default_map
;
5936 * Setup mask for cpus without special case scheduling requirements.
5937 * For now this just excludes isolated cpus, but could be used to
5938 * exclude other special cases in the future.
5940 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
5942 build_sched_domains(&cpu_default_map
);
5945 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
5951 for_each_cpu_mask(cpu
, *cpu_map
) {
5952 struct sched_group
*sched_group_allnodes
5953 = sched_group_allnodes_bycpu
[cpu
];
5954 struct sched_group
**sched_group_nodes
5955 = sched_group_nodes_bycpu
[cpu
];
5957 if (sched_group_allnodes
) {
5958 kfree(sched_group_allnodes
);
5959 sched_group_allnodes_bycpu
[cpu
] = NULL
;
5962 if (!sched_group_nodes
)
5965 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5966 cpumask_t nodemask
= node_to_cpumask(i
);
5967 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5969 cpus_and(nodemask
, nodemask
, *cpu_map
);
5970 if (cpus_empty(nodemask
))
5980 if (oldsg
!= sched_group_nodes
[i
])
5983 kfree(sched_group_nodes
);
5984 sched_group_nodes_bycpu
[cpu
] = NULL
;
5990 * Detach sched domains from a group of cpus specified in cpu_map
5991 * These cpus will now be attached to the NULL domain
5993 static inline void detach_destroy_domains(const cpumask_t
*cpu_map
)
5997 for_each_cpu_mask(i
, *cpu_map
)
5998 cpu_attach_domain(NULL
, i
);
5999 synchronize_sched();
6000 arch_destroy_sched_domains(cpu_map
);
6004 * Partition sched domains as specified by the cpumasks below.
6005 * This attaches all cpus from the cpumasks to the NULL domain,
6006 * waits for a RCU quiescent period, recalculates sched
6007 * domain information and then attaches them back to the
6008 * correct sched domains
6009 * Call with hotplug lock held
6011 void partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
6013 cpumask_t change_map
;
6015 cpus_and(*partition1
, *partition1
, cpu_online_map
);
6016 cpus_and(*partition2
, *partition2
, cpu_online_map
);
6017 cpus_or(change_map
, *partition1
, *partition2
);
6019 /* Detach sched domains from all of the affected cpus */
6020 detach_destroy_domains(&change_map
);
6021 if (!cpus_empty(*partition1
))
6022 build_sched_domains(partition1
);
6023 if (!cpus_empty(*partition2
))
6024 build_sched_domains(partition2
);
6027 #ifdef CONFIG_HOTPLUG_CPU
6029 * Force a reinitialization of the sched domains hierarchy. The domains
6030 * and groups cannot be updated in place without racing with the balancing
6031 * code, so we temporarily attach all running cpus to the NULL domain
6032 * which will prevent rebalancing while the sched domains are recalculated.
6034 static int update_sched_domains(struct notifier_block
*nfb
,
6035 unsigned long action
, void *hcpu
)
6038 case CPU_UP_PREPARE
:
6039 case CPU_DOWN_PREPARE
:
6040 detach_destroy_domains(&cpu_online_map
);
6043 case CPU_UP_CANCELED
:
6044 case CPU_DOWN_FAILED
:
6048 * Fall through and re-initialise the domains.
6055 /* The hotplug lock is already held by cpu_up/cpu_down */
6056 arch_init_sched_domains(&cpu_online_map
);
6062 void __init
sched_init_smp(void)
6065 arch_init_sched_domains(&cpu_online_map
);
6066 unlock_cpu_hotplug();
6067 /* XXX: Theoretical race here - CPU may be hotplugged now */
6068 hotcpu_notifier(update_sched_domains
, 0);
6071 void __init
sched_init_smp(void)
6074 #endif /* CONFIG_SMP */
6076 int in_sched_functions(unsigned long addr
)
6078 /* Linker adds these: start and end of __sched functions */
6079 extern char __sched_text_start
[], __sched_text_end
[];
6080 return in_lock_functions(addr
) ||
6081 (addr
>= (unsigned long)__sched_text_start
6082 && addr
< (unsigned long)__sched_text_end
);
6085 void __init
sched_init(void)
6090 for (i
= 0; i
< NR_CPUS
; i
++) {
6091 prio_array_t
*array
;
6094 spin_lock_init(&rq
->lock
);
6096 rq
->active
= rq
->arrays
;
6097 rq
->expired
= rq
->arrays
+ 1;
6098 rq
->best_expired_prio
= MAX_PRIO
;
6102 for (j
= 1; j
< 3; j
++)
6103 rq
->cpu_load
[j
] = 0;
6104 rq
->active_balance
= 0;
6106 rq
->migration_thread
= NULL
;
6107 INIT_LIST_HEAD(&rq
->migration_queue
);
6109 atomic_set(&rq
->nr_iowait
, 0);
6111 for (j
= 0; j
< 2; j
++) {
6112 array
= rq
->arrays
+ j
;
6113 for (k
= 0; k
< MAX_PRIO
; k
++) {
6114 INIT_LIST_HEAD(array
->queue
+ k
);
6115 __clear_bit(k
, array
->bitmap
);
6117 // delimiter for bitsearch
6118 __set_bit(MAX_PRIO
, array
->bitmap
);
6123 * The boot idle thread does lazy MMU switching as well:
6125 atomic_inc(&init_mm
.mm_count
);
6126 enter_lazy_tlb(&init_mm
, current
);
6129 * Make us the idle thread. Technically, schedule() should not be
6130 * called from this thread, however somewhere below it might be,
6131 * but because we are the idle thread, we just pick up running again
6132 * when this runqueue becomes "idle".
6134 init_idle(current
, smp_processor_id());
6137 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6138 void __might_sleep(char *file
, int line
)
6140 #if defined(in_atomic)
6141 static unsigned long prev_jiffy
; /* ratelimiting */
6143 if ((in_atomic() || irqs_disabled()) &&
6144 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6145 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6147 prev_jiffy
= jiffies
;
6148 printk(KERN_ERR
"Debug: sleeping function called from invalid"
6149 " context at %s:%d\n", file
, line
);
6150 printk("in_atomic():%d, irqs_disabled():%d\n",
6151 in_atomic(), irqs_disabled());
6156 EXPORT_SYMBOL(__might_sleep
);
6159 #ifdef CONFIG_MAGIC_SYSRQ
6160 void normalize_rt_tasks(void)
6162 struct task_struct
*p
;
6163 prio_array_t
*array
;
6164 unsigned long flags
;
6167 read_lock_irq(&tasklist_lock
);
6168 for_each_process (p
) {
6172 rq
= task_rq_lock(p
, &flags
);
6176 deactivate_task(p
, task_rq(p
));
6177 __setscheduler(p
, SCHED_NORMAL
, 0);
6179 __activate_task(p
, task_rq(p
));
6180 resched_task(rq
->curr
);
6183 task_rq_unlock(rq
, &flags
);
6185 read_unlock_irq(&tasklist_lock
);
6188 #endif /* CONFIG_MAGIC_SYSRQ */
6192 * These functions are only useful for the IA64 MCA handling.
6194 * They can only be called when the whole system has been
6195 * stopped - every CPU needs to be quiescent, and no scheduling
6196 * activity can take place. Using them for anything else would
6197 * be a serious bug, and as a result, they aren't even visible
6198 * under any other configuration.
6202 * curr_task - return the current task for a given cpu.
6203 * @cpu: the processor in question.
6205 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6207 task_t
*curr_task(int cpu
)
6209 return cpu_curr(cpu
);
6213 * set_curr_task - set the current task for a given cpu.
6214 * @cpu: the processor in question.
6215 * @p: the task pointer to set.
6217 * Description: This function must only be used when non-maskable interrupts
6218 * are serviced on a separate stack. It allows the architecture to switch the
6219 * notion of the current task on a cpu in a non-blocking manner. This function
6220 * must be called with all CPU's synchronized, and interrupts disabled, the
6221 * and caller must save the original value of the current task (see
6222 * curr_task() above) and restore that value before reenabling interrupts and
6223 * re-starting the system.
6225 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6227 void set_curr_task(int cpu
, task_t
*p
)