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>
52 #include <linux/kprobes.h>
55 #include <asm/unistd.h>
58 * Convert user-nice values [ -20 ... 0 ... 19 ]
59 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
62 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
63 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
64 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
67 * 'User priority' is the nice value converted to something we
68 * can work with better when scaling various scheduler parameters,
69 * it's a [ 0 ... 39 ] range.
71 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
72 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
73 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
76 * Some helpers for converting nanosecond timing to jiffy resolution
78 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
79 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
82 * These are the 'tuning knobs' of the scheduler:
84 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
85 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
86 * Timeslices get refilled after they expire.
88 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
89 #define DEF_TIMESLICE (100 * HZ / 1000)
90 #define ON_RUNQUEUE_WEIGHT 30
91 #define CHILD_PENALTY 95
92 #define PARENT_PENALTY 100
94 #define PRIO_BONUS_RATIO 25
95 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
96 #define INTERACTIVE_DELTA 2
97 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
98 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
99 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
102 * If a task is 'interactive' then we reinsert it in the active
103 * array after it has expired its current timeslice. (it will not
104 * continue to run immediately, it will still roundrobin with
105 * other interactive tasks.)
107 * This part scales the interactivity limit depending on niceness.
109 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
110 * Here are a few examples of different nice levels:
112 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
113 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
114 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
115 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
116 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
118 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
119 * priority range a task can explore, a value of '1' means the
120 * task is rated interactive.)
122 * Ie. nice +19 tasks can never get 'interactive' enough to be
123 * reinserted into the active array. And only heavily CPU-hog nice -20
124 * tasks will be expired. Default nice 0 tasks are somewhere between,
125 * it takes some effort for them to get interactive, but it's not
129 #define CURRENT_BONUS(p) \
130 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
133 #define GRANULARITY (10 * HZ / 1000 ? : 1)
136 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
137 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
140 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
141 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
144 #define SCALE(v1,v1_max,v2_max) \
145 (v1) * (v2_max) / (v1_max)
148 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
151 #define TASK_INTERACTIVE(p) \
152 ((p)->prio <= (p)->static_prio - DELTA(p))
154 #define INTERACTIVE_SLEEP(p) \
155 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
156 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
158 #define TASK_PREEMPTS_CURR(p, rq) \
159 ((p)->prio < (rq)->curr->prio)
162 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
163 * to time slice values: [800ms ... 100ms ... 5ms]
165 * The higher a thread's priority, the bigger timeslices
166 * it gets during one round of execution. But even the lowest
167 * priority thread gets MIN_TIMESLICE worth of execution time.
170 #define SCALE_PRIO(x, prio) \
171 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
173 static unsigned int task_timeslice(task_t
*p
)
175 if (p
->static_prio
< NICE_TO_PRIO(0))
176 return SCALE_PRIO(DEF_TIMESLICE
*4, p
->static_prio
);
178 return SCALE_PRIO(DEF_TIMESLICE
, p
->static_prio
);
180 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \
181 < (long long) (sd)->cache_hot_time)
184 * These are the runqueue data structures:
187 typedef struct runqueue runqueue_t
;
190 unsigned int nr_active
;
191 DECLARE_BITMAP(bitmap
, MAX_PRIO
+1); /* include 1 bit for delimiter */
192 struct list_head queue
[MAX_PRIO
];
196 * This is the main, per-CPU runqueue data structure.
198 * Locking rule: those places that want to lock multiple runqueues
199 * (such as the load balancing or the thread migration code), lock
200 * acquire operations must be ordered by ascending &runqueue.
206 * nr_running and cpu_load should be in the same cacheline because
207 * remote CPUs use both these fields when doing load calculation.
209 unsigned long nr_running
;
211 unsigned long cpu_load
[3];
213 unsigned long long nr_switches
;
216 * This is part of a global counter where only the total sum
217 * over all CPUs matters. A task can increase this counter on
218 * one CPU and if it got migrated afterwards it may decrease
219 * it on another CPU. Always updated under the runqueue lock:
221 unsigned long nr_uninterruptible
;
223 unsigned long expired_timestamp
;
224 unsigned long long timestamp_last_tick
;
226 struct mm_struct
*prev_mm
;
227 prio_array_t
*active
, *expired
, arrays
[2];
228 int best_expired_prio
;
232 struct sched_domain
*sd
;
234 /* For active balancing */
238 task_t
*migration_thread
;
239 struct list_head migration_queue
;
242 #ifdef CONFIG_SCHEDSTATS
244 struct sched_info rq_sched_info
;
246 /* sys_sched_yield() stats */
247 unsigned long yld_exp_empty
;
248 unsigned long yld_act_empty
;
249 unsigned long yld_both_empty
;
250 unsigned long yld_cnt
;
252 /* schedule() stats */
253 unsigned long sched_switch
;
254 unsigned long sched_cnt
;
255 unsigned long sched_goidle
;
257 /* try_to_wake_up() stats */
258 unsigned long ttwu_cnt
;
259 unsigned long ttwu_local
;
263 static DEFINE_PER_CPU(struct runqueue
, runqueues
);
266 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
267 * See detach_destroy_domains: synchronize_sched for details.
269 * The domain tree of any CPU may only be accessed from within
270 * preempt-disabled sections.
272 #define for_each_domain(cpu, domain) \
273 for (domain = rcu_dereference(cpu_rq(cpu)->sd); domain; domain = domain->parent)
275 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
276 #define this_rq() (&__get_cpu_var(runqueues))
277 #define task_rq(p) cpu_rq(task_cpu(p))
278 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
280 #ifndef prepare_arch_switch
281 # define prepare_arch_switch(next) do { } while (0)
283 #ifndef finish_arch_switch
284 # define finish_arch_switch(prev) do { } while (0)
287 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
288 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
290 return rq
->curr
== p
;
293 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
297 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
299 #ifdef CONFIG_DEBUG_SPINLOCK
300 /* this is a valid case when another task releases the spinlock */
301 rq
->lock
.owner
= current
;
303 spin_unlock_irq(&rq
->lock
);
306 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
307 static inline int task_running(runqueue_t
*rq
, task_t
*p
)
312 return rq
->curr
== p
;
316 static inline void prepare_lock_switch(runqueue_t
*rq
, task_t
*next
)
320 * We can optimise this out completely for !SMP, because the
321 * SMP rebalancing from interrupt is the only thing that cares
326 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
327 spin_unlock_irq(&rq
->lock
);
329 spin_unlock(&rq
->lock
);
333 static inline void finish_lock_switch(runqueue_t
*rq
, task_t
*prev
)
337 * After ->oncpu is cleared, the task can be moved to a different CPU.
338 * We must ensure this doesn't happen until the switch is completely
344 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
348 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
351 * task_rq_lock - lock the runqueue a given task resides on and disable
352 * interrupts. Note the ordering: we can safely lookup the task_rq without
353 * explicitly disabling preemption.
355 static inline runqueue_t
*task_rq_lock(task_t
*p
, unsigned long *flags
)
361 local_irq_save(*flags
);
363 spin_lock(&rq
->lock
);
364 if (unlikely(rq
!= task_rq(p
))) {
365 spin_unlock_irqrestore(&rq
->lock
, *flags
);
366 goto repeat_lock_task
;
371 static inline void task_rq_unlock(runqueue_t
*rq
, unsigned long *flags
)
374 spin_unlock_irqrestore(&rq
->lock
, *flags
);
377 #ifdef CONFIG_SCHEDSTATS
379 * bump this up when changing the output format or the meaning of an existing
380 * format, so that tools can adapt (or abort)
382 #define SCHEDSTAT_VERSION 12
384 static int show_schedstat(struct seq_file
*seq
, void *v
)
388 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
389 seq_printf(seq
, "timestamp %lu\n", jiffies
);
390 for_each_online_cpu(cpu
) {
391 runqueue_t
*rq
= cpu_rq(cpu
);
393 struct sched_domain
*sd
;
397 /* runqueue-specific stats */
399 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
400 cpu
, rq
->yld_both_empty
,
401 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
402 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
403 rq
->ttwu_cnt
, rq
->ttwu_local
,
404 rq
->rq_sched_info
.cpu_time
,
405 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
407 seq_printf(seq
, "\n");
410 /* domain-specific stats */
412 for_each_domain(cpu
, sd
) {
413 enum idle_type itype
;
414 char mask_str
[NR_CPUS
];
416 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
417 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
418 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
420 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu",
422 sd
->lb_balanced
[itype
],
423 sd
->lb_failed
[itype
],
424 sd
->lb_imbalance
[itype
],
425 sd
->lb_gained
[itype
],
426 sd
->lb_hot_gained
[itype
],
427 sd
->lb_nobusyq
[itype
],
428 sd
->lb_nobusyg
[itype
]);
430 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
431 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
432 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
433 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
434 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
, sd
->ttwu_move_balance
);
442 static int schedstat_open(struct inode
*inode
, struct file
*file
)
444 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
445 char *buf
= kmalloc(size
, GFP_KERNEL
);
451 res
= single_open(file
, show_schedstat
, NULL
);
453 m
= file
->private_data
;
461 struct file_operations proc_schedstat_operations
= {
462 .open
= schedstat_open
,
465 .release
= single_release
,
468 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
469 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
470 #else /* !CONFIG_SCHEDSTATS */
471 # define schedstat_inc(rq, field) do { } while (0)
472 # define schedstat_add(rq, field, amt) do { } while (0)
476 * rq_lock - lock a given runqueue and disable interrupts.
478 static inline runqueue_t
*this_rq_lock(void)
485 spin_lock(&rq
->lock
);
490 #ifdef CONFIG_SCHEDSTATS
492 * Called when a process is dequeued from the active array and given
493 * the cpu. We should note that with the exception of interactive
494 * tasks, the expired queue will become the active queue after the active
495 * queue is empty, without explicitly dequeuing and requeuing tasks in the
496 * expired queue. (Interactive tasks may be requeued directly to the
497 * active queue, thus delaying tasks in the expired queue from running;
498 * see scheduler_tick()).
500 * This function is only called from sched_info_arrive(), rather than
501 * dequeue_task(). Even though a task may be queued and dequeued multiple
502 * times as it is shuffled about, we're really interested in knowing how
503 * long it was from the *first* time it was queued to the time that it
506 static inline void sched_info_dequeued(task_t
*t
)
508 t
->sched_info
.last_queued
= 0;
512 * Called when a task finally hits the cpu. We can now calculate how
513 * long it was waiting to run. We also note when it began so that we
514 * can keep stats on how long its timeslice is.
516 static void sched_info_arrive(task_t
*t
)
518 unsigned long now
= jiffies
, diff
= 0;
519 struct runqueue
*rq
= task_rq(t
);
521 if (t
->sched_info
.last_queued
)
522 diff
= now
- t
->sched_info
.last_queued
;
523 sched_info_dequeued(t
);
524 t
->sched_info
.run_delay
+= diff
;
525 t
->sched_info
.last_arrival
= now
;
526 t
->sched_info
.pcnt
++;
531 rq
->rq_sched_info
.run_delay
+= diff
;
532 rq
->rq_sched_info
.pcnt
++;
536 * Called when a process is queued into either the active or expired
537 * array. The time is noted and later used to determine how long we
538 * had to wait for us to reach the cpu. Since the expired queue will
539 * become the active queue after active queue is empty, without dequeuing
540 * and requeuing any tasks, we are interested in queuing to either. It
541 * is unusual but not impossible for tasks to be dequeued and immediately
542 * requeued in the same or another array: this can happen in sched_yield(),
543 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
546 * This function is only called from enqueue_task(), but also only updates
547 * the timestamp if it is already not set. It's assumed that
548 * sched_info_dequeued() will clear that stamp when appropriate.
550 static inline void sched_info_queued(task_t
*t
)
552 if (!t
->sched_info
.last_queued
)
553 t
->sched_info
.last_queued
= jiffies
;
557 * Called when a process ceases being the active-running process, either
558 * voluntarily or involuntarily. Now we can calculate how long we ran.
560 static inline void sched_info_depart(task_t
*t
)
562 struct runqueue
*rq
= task_rq(t
);
563 unsigned long diff
= jiffies
- t
->sched_info
.last_arrival
;
565 t
->sched_info
.cpu_time
+= diff
;
568 rq
->rq_sched_info
.cpu_time
+= diff
;
572 * Called when tasks are switched involuntarily due, typically, to expiring
573 * their time slice. (This may also be called when switching to or from
574 * the idle task.) We are only called when prev != next.
576 static inline void sched_info_switch(task_t
*prev
, task_t
*next
)
578 struct runqueue
*rq
= task_rq(prev
);
581 * prev now departs the cpu. It's not interesting to record
582 * stats about how efficient we were at scheduling the idle
585 if (prev
!= rq
->idle
)
586 sched_info_depart(prev
);
588 if (next
!= rq
->idle
)
589 sched_info_arrive(next
);
592 #define sched_info_queued(t) do { } while (0)
593 #define sched_info_switch(t, next) do { } while (0)
594 #endif /* CONFIG_SCHEDSTATS */
597 * Adding/removing a task to/from a priority array:
599 static void dequeue_task(struct task_struct
*p
, prio_array_t
*array
)
602 list_del(&p
->run_list
);
603 if (list_empty(array
->queue
+ p
->prio
))
604 __clear_bit(p
->prio
, array
->bitmap
);
607 static void enqueue_task(struct task_struct
*p
, prio_array_t
*array
)
609 sched_info_queued(p
);
610 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
611 __set_bit(p
->prio
, array
->bitmap
);
617 * Put task to the end of the run list without the overhead of dequeue
618 * followed by enqueue.
620 static void requeue_task(struct task_struct
*p
, prio_array_t
*array
)
622 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
625 static inline void enqueue_task_head(struct task_struct
*p
, prio_array_t
*array
)
627 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
628 __set_bit(p
->prio
, array
->bitmap
);
634 * effective_prio - return the priority that is based on the static
635 * priority but is modified by bonuses/penalties.
637 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
638 * into the -5 ... 0 ... +5 bonus/penalty range.
640 * We use 25% of the full 0...39 priority range so that:
642 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
643 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
645 * Both properties are important to certain workloads.
647 static int effective_prio(task_t
*p
)
654 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
656 prio
= p
->static_prio
- bonus
;
657 if (prio
< MAX_RT_PRIO
)
659 if (prio
> MAX_PRIO
-1)
665 * __activate_task - move a task to the runqueue.
667 static void __activate_task(task_t
*p
, runqueue_t
*rq
)
669 prio_array_t
*target
= rq
->active
;
672 target
= rq
->expired
;
673 enqueue_task(p
, target
);
678 * __activate_idle_task - move idle task to the _front_ of runqueue.
680 static inline void __activate_idle_task(task_t
*p
, runqueue_t
*rq
)
682 enqueue_task_head(p
, rq
->active
);
686 static int recalc_task_prio(task_t
*p
, unsigned long long now
)
688 /* Caller must always ensure 'now >= p->timestamp' */
689 unsigned long sleep_time
= now
- p
->timestamp
;
694 if (likely(sleep_time
> 0)) {
696 * This ceiling is set to the lowest priority that would allow
697 * a task to be reinserted into the active array on timeslice
700 unsigned long ceiling
= INTERACTIVE_SLEEP(p
);
702 if (p
->mm
&& sleep_time
> ceiling
&& p
->sleep_avg
< ceiling
) {
704 * Prevents user tasks from achieving best priority
705 * with one single large enough sleep.
707 p
->sleep_avg
= ceiling
;
709 * Using INTERACTIVE_SLEEP() as a ceiling places a
710 * nice(0) task 1ms sleep away from promotion, and
711 * gives it 700ms to round-robin with no chance of
712 * being demoted. This is more than generous, so
713 * mark this sleep as non-interactive to prevent the
714 * on-runqueue bonus logic from intervening should
715 * this task not receive cpu immediately.
717 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
720 * Tasks waking from uninterruptible sleep are
721 * limited in their sleep_avg rise as they
722 * are likely to be waiting on I/O
724 if (p
->sleep_type
== SLEEP_NONINTERACTIVE
&& p
->mm
) {
725 if (p
->sleep_avg
>= ceiling
)
727 else if (p
->sleep_avg
+ sleep_time
>=
729 p
->sleep_avg
= ceiling
;
735 * This code gives a bonus to interactive tasks.
737 * The boost works by updating the 'average sleep time'
738 * value here, based on ->timestamp. The more time a
739 * task spends sleeping, the higher the average gets -
740 * and the higher the priority boost gets as well.
742 p
->sleep_avg
+= sleep_time
;
745 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
746 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
749 return effective_prio(p
);
753 * activate_task - move a task to the runqueue and do priority recalculation
755 * Update all the scheduling statistics stuff. (sleep average
756 * calculation, priority modifiers, etc.)
758 static void activate_task(task_t
*p
, runqueue_t
*rq
, int local
)
760 unsigned long long now
;
765 /* Compensate for drifting sched_clock */
766 runqueue_t
*this_rq
= this_rq();
767 now
= (now
- this_rq
->timestamp_last_tick
)
768 + rq
->timestamp_last_tick
;
773 p
->prio
= recalc_task_prio(p
, now
);
776 * This checks to make sure it's not an uninterruptible task
777 * that is now waking up.
779 if (p
->sleep_type
== SLEEP_NORMAL
) {
781 * Tasks which were woken up by interrupts (ie. hw events)
782 * are most likely of interactive nature. So we give them
783 * the credit of extending their sleep time to the period
784 * of time they spend on the runqueue, waiting for execution
785 * on a CPU, first time around:
788 p
->sleep_type
= SLEEP_INTERRUPTED
;
791 * Normal first-time wakeups get a credit too for
792 * on-runqueue time, but it will be weighted down:
794 p
->sleep_type
= SLEEP_INTERACTIVE
;
799 __activate_task(p
, rq
);
803 * deactivate_task - remove a task from the runqueue.
805 static void deactivate_task(struct task_struct
*p
, runqueue_t
*rq
)
808 dequeue_task(p
, p
->array
);
813 * resched_task - mark a task 'to be rescheduled now'.
815 * On UP this means the setting of the need_resched flag, on SMP it
816 * might also involve a cross-CPU call to trigger the scheduler on
821 #ifndef tsk_is_polling
822 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
825 static void resched_task(task_t
*p
)
829 assert_spin_locked(&task_rq(p
)->lock
);
831 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
834 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
837 if (cpu
== smp_processor_id())
840 /* NEED_RESCHED must be visible before we test polling */
842 if (!tsk_is_polling(p
))
843 smp_send_reschedule(cpu
);
846 static inline void resched_task(task_t
*p
)
848 assert_spin_locked(&task_rq(p
)->lock
);
849 set_tsk_need_resched(p
);
854 * task_curr - is this task currently executing on a CPU?
855 * @p: the task in question.
857 inline int task_curr(const task_t
*p
)
859 return cpu_curr(task_cpu(p
)) == p
;
864 struct list_head list
;
869 struct completion done
;
873 * The task's runqueue lock must be held.
874 * Returns true if you have to wait for migration thread.
876 static int migrate_task(task_t
*p
, int dest_cpu
, migration_req_t
*req
)
878 runqueue_t
*rq
= task_rq(p
);
881 * If the task is not on a runqueue (and not running), then
882 * it is sufficient to simply update the task's cpu field.
884 if (!p
->array
&& !task_running(rq
, p
)) {
885 set_task_cpu(p
, dest_cpu
);
889 init_completion(&req
->done
);
891 req
->dest_cpu
= dest_cpu
;
892 list_add(&req
->list
, &rq
->migration_queue
);
897 * wait_task_inactive - wait for a thread to unschedule.
899 * The caller must ensure that the task *will* unschedule sometime soon,
900 * else this function might spin for a *long* time. This function can't
901 * be called with interrupts off, or it may introduce deadlock with
902 * smp_call_function() if an IPI is sent by the same process we are
903 * waiting to become inactive.
905 void wait_task_inactive(task_t
*p
)
912 rq
= task_rq_lock(p
, &flags
);
913 /* Must be off runqueue entirely, not preempted. */
914 if (unlikely(p
->array
|| task_running(rq
, p
))) {
915 /* If it's preempted, we yield. It could be a while. */
916 preempted
= !task_running(rq
, p
);
917 task_rq_unlock(rq
, &flags
);
923 task_rq_unlock(rq
, &flags
);
927 * kick_process - kick a running thread to enter/exit the kernel
928 * @p: the to-be-kicked thread
930 * Cause a process which is running on another CPU to enter
931 * kernel-mode, without any delay. (to get signals handled.)
933 * NOTE: this function doesnt have to take the runqueue lock,
934 * because all it wants to ensure is that the remote task enters
935 * the kernel. If the IPI races and the task has been migrated
936 * to another CPU then no harm is done and the purpose has been
939 void kick_process(task_t
*p
)
945 if ((cpu
!= smp_processor_id()) && task_curr(p
))
946 smp_send_reschedule(cpu
);
951 * Return a low guess at the load of a migration-source cpu.
953 * We want to under-estimate the load of migration sources, to
954 * balance conservatively.
956 static inline unsigned long source_load(int cpu
, int type
)
958 runqueue_t
*rq
= cpu_rq(cpu
);
959 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
963 return min(rq
->cpu_load
[type
-1], load_now
);
967 * Return a high guess at the load of a migration-target cpu
969 static inline unsigned long target_load(int cpu
, int type
)
971 runqueue_t
*rq
= cpu_rq(cpu
);
972 unsigned long load_now
= rq
->nr_running
* SCHED_LOAD_SCALE
;
976 return max(rq
->cpu_load
[type
-1], load_now
);
980 * find_idlest_group finds and returns the least busy CPU group within the
983 static struct sched_group
*
984 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
986 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
987 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
988 int load_idx
= sd
->forkexec_idx
;
989 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
992 unsigned long load
, avg_load
;
996 /* Skip over this group if it has no CPUs allowed */
997 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1000 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1002 /* Tally up the load of all CPUs in the group */
1005 for_each_cpu_mask(i
, group
->cpumask
) {
1006 /* Bias balancing toward cpus of our domain */
1008 load
= source_load(i
, load_idx
);
1010 load
= target_load(i
, load_idx
);
1015 /* Adjust by relative CPU power of the group */
1016 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1019 this_load
= avg_load
;
1021 } else if (avg_load
< min_load
) {
1022 min_load
= avg_load
;
1026 group
= group
->next
;
1027 } while (group
!= sd
->groups
);
1029 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1035 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1038 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1041 unsigned long load
, min_load
= ULONG_MAX
;
1045 /* Traverse only the allowed CPUs */
1046 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1048 for_each_cpu_mask(i
, tmp
) {
1049 load
= source_load(i
, 0);
1051 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1061 * sched_balance_self: balance the current task (running on cpu) in domains
1062 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1065 * Balance, ie. select the least loaded group.
1067 * Returns the target CPU number, or the same CPU if no balancing is needed.
1069 * preempt must be disabled.
1071 static int sched_balance_self(int cpu
, int flag
)
1073 struct task_struct
*t
= current
;
1074 struct sched_domain
*tmp
, *sd
= NULL
;
1076 for_each_domain(cpu
, tmp
) {
1077 if (tmp
->flags
& flag
)
1083 struct sched_group
*group
;
1088 group
= find_idlest_group(sd
, t
, cpu
);
1092 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1093 if (new_cpu
== -1 || new_cpu
== cpu
)
1096 /* Now try balancing at a lower domain level */
1100 weight
= cpus_weight(span
);
1101 for_each_domain(cpu
, tmp
) {
1102 if (weight
<= cpus_weight(tmp
->span
))
1104 if (tmp
->flags
& flag
)
1107 /* while loop will break here if sd == NULL */
1113 #endif /* CONFIG_SMP */
1116 * wake_idle() will wake a task on an idle cpu if task->cpu is
1117 * not idle and an idle cpu is available. The span of cpus to
1118 * search starts with cpus closest then further out as needed,
1119 * so we always favor a closer, idle cpu.
1121 * Returns the CPU we should wake onto.
1123 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1124 static int wake_idle(int cpu
, task_t
*p
)
1127 struct sched_domain
*sd
;
1133 for_each_domain(cpu
, sd
) {
1134 if (sd
->flags
& SD_WAKE_IDLE
) {
1135 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1136 for_each_cpu_mask(i
, tmp
) {
1147 static inline int wake_idle(int cpu
, task_t
*p
)
1154 * try_to_wake_up - wake up a thread
1155 * @p: the to-be-woken-up thread
1156 * @state: the mask of task states that can be woken
1157 * @sync: do a synchronous wakeup?
1159 * Put it on the run-queue if it's not already there. The "current"
1160 * thread is always on the run-queue (except when the actual
1161 * re-schedule is in progress), and as such you're allowed to do
1162 * the simpler "current->state = TASK_RUNNING" to mark yourself
1163 * runnable without the overhead of this.
1165 * returns failure only if the task is already active.
1167 static int try_to_wake_up(task_t
*p
, unsigned int state
, int sync
)
1169 int cpu
, this_cpu
, success
= 0;
1170 unsigned long flags
;
1174 unsigned long load
, this_load
;
1175 struct sched_domain
*sd
, *this_sd
= NULL
;
1179 rq
= task_rq_lock(p
, &flags
);
1180 old_state
= p
->state
;
1181 if (!(old_state
& state
))
1188 this_cpu
= smp_processor_id();
1191 if (unlikely(task_running(rq
, p
)))
1196 schedstat_inc(rq
, ttwu_cnt
);
1197 if (cpu
== this_cpu
) {
1198 schedstat_inc(rq
, ttwu_local
);
1202 for_each_domain(this_cpu
, sd
) {
1203 if (cpu_isset(cpu
, sd
->span
)) {
1204 schedstat_inc(sd
, ttwu_wake_remote
);
1210 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1214 * Check for affine wakeup and passive balancing possibilities.
1217 int idx
= this_sd
->wake_idx
;
1218 unsigned int imbalance
;
1220 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1222 load
= source_load(cpu
, idx
);
1223 this_load
= target_load(this_cpu
, idx
);
1225 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1227 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1228 unsigned long tl
= this_load
;
1230 * If sync wakeup then subtract the (maximum possible)
1231 * effect of the currently running task from the load
1232 * of the current CPU:
1235 tl
-= SCHED_LOAD_SCALE
;
1238 tl
+ target_load(cpu
, idx
) <= SCHED_LOAD_SCALE
) ||
1239 100*(tl
+ SCHED_LOAD_SCALE
) <= imbalance
*load
) {
1241 * This domain has SD_WAKE_AFFINE and
1242 * p is cache cold in this domain, and
1243 * there is no bad imbalance.
1245 schedstat_inc(this_sd
, ttwu_move_affine
);
1251 * Start passive balancing when half the imbalance_pct
1254 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1255 if (imbalance
*this_load
<= 100*load
) {
1256 schedstat_inc(this_sd
, ttwu_move_balance
);
1262 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1264 new_cpu
= wake_idle(new_cpu
, p
);
1265 if (new_cpu
!= cpu
) {
1266 set_task_cpu(p
, new_cpu
);
1267 task_rq_unlock(rq
, &flags
);
1268 /* might preempt at this point */
1269 rq
= task_rq_lock(p
, &flags
);
1270 old_state
= p
->state
;
1271 if (!(old_state
& state
))
1276 this_cpu
= smp_processor_id();
1281 #endif /* CONFIG_SMP */
1282 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1283 rq
->nr_uninterruptible
--;
1285 * Tasks on involuntary sleep don't earn
1286 * sleep_avg beyond just interactive state.
1288 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1292 * Tasks that have marked their sleep as noninteractive get
1293 * woken up with their sleep average not weighted in an
1296 if (old_state
& TASK_NONINTERACTIVE
)
1297 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1300 activate_task(p
, rq
, cpu
== this_cpu
);
1302 * Sync wakeups (i.e. those types of wakeups where the waker
1303 * has indicated that it will leave the CPU in short order)
1304 * don't trigger a preemption, if the woken up task will run on
1305 * this cpu. (in this case the 'I will reschedule' promise of
1306 * the waker guarantees that the freshly woken up task is going
1307 * to be considered on this CPU.)
1309 if (!sync
|| cpu
!= this_cpu
) {
1310 if (TASK_PREEMPTS_CURR(p
, rq
))
1311 resched_task(rq
->curr
);
1316 p
->state
= TASK_RUNNING
;
1318 task_rq_unlock(rq
, &flags
);
1323 int fastcall
wake_up_process(task_t
*p
)
1325 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1326 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1329 EXPORT_SYMBOL(wake_up_process
);
1331 int fastcall
wake_up_state(task_t
*p
, unsigned int state
)
1333 return try_to_wake_up(p
, state
, 0);
1337 * Perform scheduler related setup for a newly forked process p.
1338 * p is forked by current.
1340 void fastcall
sched_fork(task_t
*p
, int clone_flags
)
1342 int cpu
= get_cpu();
1345 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1347 set_task_cpu(p
, cpu
);
1350 * We mark the process as running here, but have not actually
1351 * inserted it onto the runqueue yet. This guarantees that
1352 * nobody will actually run it, and a signal or other external
1353 * event cannot wake it up and insert it on the runqueue either.
1355 p
->state
= TASK_RUNNING
;
1356 INIT_LIST_HEAD(&p
->run_list
);
1358 #ifdef CONFIG_SCHEDSTATS
1359 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1361 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1364 #ifdef CONFIG_PREEMPT
1365 /* Want to start with kernel preemption disabled. */
1366 task_thread_info(p
)->preempt_count
= 1;
1369 * Share the timeslice between parent and child, thus the
1370 * total amount of pending timeslices in the system doesn't change,
1371 * resulting in more scheduling fairness.
1373 local_irq_disable();
1374 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1376 * The remainder of the first timeslice might be recovered by
1377 * the parent if the child exits early enough.
1379 p
->first_time_slice
= 1;
1380 current
->time_slice
>>= 1;
1381 p
->timestamp
= sched_clock();
1382 if (unlikely(!current
->time_slice
)) {
1384 * This case is rare, it happens when the parent has only
1385 * a single jiffy left from its timeslice. Taking the
1386 * runqueue lock is not a problem.
1388 current
->time_slice
= 1;
1396 * wake_up_new_task - wake up a newly created task for the first time.
1398 * This function will do some initial scheduler statistics housekeeping
1399 * that must be done for every newly created context, then puts the task
1400 * on the runqueue and wakes it.
1402 void fastcall
wake_up_new_task(task_t
*p
, unsigned long clone_flags
)
1404 unsigned long flags
;
1406 runqueue_t
*rq
, *this_rq
;
1408 rq
= task_rq_lock(p
, &flags
);
1409 BUG_ON(p
->state
!= TASK_RUNNING
);
1410 this_cpu
= smp_processor_id();
1414 * We decrease the sleep average of forking parents
1415 * and children as well, to keep max-interactive tasks
1416 * from forking tasks that are max-interactive. The parent
1417 * (current) is done further down, under its lock.
1419 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1420 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1422 p
->prio
= effective_prio(p
);
1424 if (likely(cpu
== this_cpu
)) {
1425 if (!(clone_flags
& CLONE_VM
)) {
1427 * The VM isn't cloned, so we're in a good position to
1428 * do child-runs-first in anticipation of an exec. This
1429 * usually avoids a lot of COW overhead.
1431 if (unlikely(!current
->array
))
1432 __activate_task(p
, rq
);
1434 p
->prio
= current
->prio
;
1435 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1436 p
->array
= current
->array
;
1437 p
->array
->nr_active
++;
1442 /* Run child last */
1443 __activate_task(p
, rq
);
1445 * We skip the following code due to cpu == this_cpu
1447 * task_rq_unlock(rq, &flags);
1448 * this_rq = task_rq_lock(current, &flags);
1452 this_rq
= cpu_rq(this_cpu
);
1455 * Not the local CPU - must adjust timestamp. This should
1456 * get optimised away in the !CONFIG_SMP case.
1458 p
->timestamp
= (p
->timestamp
- this_rq
->timestamp_last_tick
)
1459 + rq
->timestamp_last_tick
;
1460 __activate_task(p
, rq
);
1461 if (TASK_PREEMPTS_CURR(p
, rq
))
1462 resched_task(rq
->curr
);
1465 * Parent and child are on different CPUs, now get the
1466 * parent runqueue to update the parent's ->sleep_avg:
1468 task_rq_unlock(rq
, &flags
);
1469 this_rq
= task_rq_lock(current
, &flags
);
1471 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1472 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1473 task_rq_unlock(this_rq
, &flags
);
1477 * Potentially available exiting-child timeslices are
1478 * retrieved here - this way the parent does not get
1479 * penalized for creating too many threads.
1481 * (this cannot be used to 'generate' timeslices
1482 * artificially, because any timeslice recovered here
1483 * was given away by the parent in the first place.)
1485 void fastcall
sched_exit(task_t
*p
)
1487 unsigned long flags
;
1491 * If the child was a (relative-) CPU hog then decrease
1492 * the sleep_avg of the parent as well.
1494 rq
= task_rq_lock(p
->parent
, &flags
);
1495 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1496 p
->parent
->time_slice
+= p
->time_slice
;
1497 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1498 p
->parent
->time_slice
= task_timeslice(p
);
1500 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1501 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1502 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1504 task_rq_unlock(rq
, &flags
);
1508 * prepare_task_switch - prepare to switch tasks
1509 * @rq: the runqueue preparing to switch
1510 * @next: the task we are going to switch to.
1512 * This is called with the rq lock held and interrupts off. It must
1513 * be paired with a subsequent finish_task_switch after the context
1516 * prepare_task_switch sets up locking and calls architecture specific
1519 static inline void prepare_task_switch(runqueue_t
*rq
, task_t
*next
)
1521 prepare_lock_switch(rq
, next
);
1522 prepare_arch_switch(next
);
1526 * finish_task_switch - clean up after a task-switch
1527 * @rq: runqueue associated with task-switch
1528 * @prev: the thread we just switched away from.
1530 * finish_task_switch must be called after the context switch, paired
1531 * with a prepare_task_switch call before the context switch.
1532 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1533 * and do any other architecture-specific cleanup actions.
1535 * Note that we may have delayed dropping an mm in context_switch(). If
1536 * so, we finish that here outside of the runqueue lock. (Doing it
1537 * with the lock held can cause deadlocks; see schedule() for
1540 static inline void finish_task_switch(runqueue_t
*rq
, task_t
*prev
)
1541 __releases(rq
->lock
)
1543 struct mm_struct
*mm
= rq
->prev_mm
;
1544 unsigned long prev_task_flags
;
1549 * A task struct has one reference for the use as "current".
1550 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1551 * calls schedule one last time. The schedule call will never return,
1552 * and the scheduled task must drop that reference.
1553 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1554 * still held, otherwise prev could be scheduled on another cpu, die
1555 * there before we look at prev->state, and then the reference would
1557 * Manfred Spraul <manfred@colorfullife.com>
1559 prev_task_flags
= prev
->flags
;
1560 finish_arch_switch(prev
);
1561 finish_lock_switch(rq
, prev
);
1564 if (unlikely(prev_task_flags
& PF_DEAD
)) {
1566 * Remove function-return probe instances associated with this
1567 * task and put them back on the free list.
1569 kprobe_flush_task(prev
);
1570 put_task_struct(prev
);
1575 * schedule_tail - first thing a freshly forked thread must call.
1576 * @prev: the thread we just switched away from.
1578 asmlinkage
void schedule_tail(task_t
*prev
)
1579 __releases(rq
->lock
)
1581 runqueue_t
*rq
= this_rq();
1582 finish_task_switch(rq
, prev
);
1583 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1584 /* In this case, finish_task_switch does not reenable preemption */
1587 if (current
->set_child_tid
)
1588 put_user(current
->pid
, current
->set_child_tid
);
1592 * context_switch - switch to the new MM and the new
1593 * thread's register state.
1596 task_t
* context_switch(runqueue_t
*rq
, task_t
*prev
, task_t
*next
)
1598 struct mm_struct
*mm
= next
->mm
;
1599 struct mm_struct
*oldmm
= prev
->active_mm
;
1601 if (unlikely(!mm
)) {
1602 next
->active_mm
= oldmm
;
1603 atomic_inc(&oldmm
->mm_count
);
1604 enter_lazy_tlb(oldmm
, next
);
1606 switch_mm(oldmm
, mm
, next
);
1608 if (unlikely(!prev
->mm
)) {
1609 prev
->active_mm
= NULL
;
1610 WARN_ON(rq
->prev_mm
);
1611 rq
->prev_mm
= oldmm
;
1614 /* Here we just switch the register state and the stack. */
1615 switch_to(prev
, next
, prev
);
1621 * nr_running, nr_uninterruptible and nr_context_switches:
1623 * externally visible scheduler statistics: current number of runnable
1624 * threads, current number of uninterruptible-sleeping threads, total
1625 * number of context switches performed since bootup.
1627 unsigned long nr_running(void)
1629 unsigned long i
, sum
= 0;
1631 for_each_online_cpu(i
)
1632 sum
+= cpu_rq(i
)->nr_running
;
1637 unsigned long nr_uninterruptible(void)
1639 unsigned long i
, sum
= 0;
1641 for_each_possible_cpu(i
)
1642 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1645 * Since we read the counters lockless, it might be slightly
1646 * inaccurate. Do not allow it to go below zero though:
1648 if (unlikely((long)sum
< 0))
1654 unsigned long long nr_context_switches(void)
1657 unsigned long long sum
= 0;
1659 for_each_possible_cpu(i
)
1660 sum
+= cpu_rq(i
)->nr_switches
;
1665 unsigned long nr_iowait(void)
1667 unsigned long i
, sum
= 0;
1669 for_each_possible_cpu(i
)
1670 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1675 unsigned long nr_active(void)
1677 unsigned long i
, running
= 0, uninterruptible
= 0;
1679 for_each_online_cpu(i
) {
1680 running
+= cpu_rq(i
)->nr_running
;
1681 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
1684 if (unlikely((long)uninterruptible
< 0))
1685 uninterruptible
= 0;
1687 return running
+ uninterruptible
;
1693 * double_rq_lock - safely lock two runqueues
1695 * Note this does not disable interrupts like task_rq_lock,
1696 * you need to do so manually before calling.
1698 static void double_rq_lock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1699 __acquires(rq1
->lock
)
1700 __acquires(rq2
->lock
)
1703 spin_lock(&rq1
->lock
);
1704 __acquire(rq2
->lock
); /* Fake it out ;) */
1707 spin_lock(&rq1
->lock
);
1708 spin_lock(&rq2
->lock
);
1710 spin_lock(&rq2
->lock
);
1711 spin_lock(&rq1
->lock
);
1717 * double_rq_unlock - safely unlock two runqueues
1719 * Note this does not restore interrupts like task_rq_unlock,
1720 * you need to do so manually after calling.
1722 static void double_rq_unlock(runqueue_t
*rq1
, runqueue_t
*rq2
)
1723 __releases(rq1
->lock
)
1724 __releases(rq2
->lock
)
1726 spin_unlock(&rq1
->lock
);
1728 spin_unlock(&rq2
->lock
);
1730 __release(rq2
->lock
);
1734 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1736 static void double_lock_balance(runqueue_t
*this_rq
, runqueue_t
*busiest
)
1737 __releases(this_rq
->lock
)
1738 __acquires(busiest
->lock
)
1739 __acquires(this_rq
->lock
)
1741 if (unlikely(!spin_trylock(&busiest
->lock
))) {
1742 if (busiest
< this_rq
) {
1743 spin_unlock(&this_rq
->lock
);
1744 spin_lock(&busiest
->lock
);
1745 spin_lock(&this_rq
->lock
);
1747 spin_lock(&busiest
->lock
);
1752 * If dest_cpu is allowed for this process, migrate the task to it.
1753 * This is accomplished by forcing the cpu_allowed mask to only
1754 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1755 * the cpu_allowed mask is restored.
1757 static void sched_migrate_task(task_t
*p
, int dest_cpu
)
1759 migration_req_t req
;
1761 unsigned long flags
;
1763 rq
= task_rq_lock(p
, &flags
);
1764 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
1765 || unlikely(cpu_is_offline(dest_cpu
)))
1768 /* force the process onto the specified CPU */
1769 if (migrate_task(p
, dest_cpu
, &req
)) {
1770 /* Need to wait for migration thread (might exit: take ref). */
1771 struct task_struct
*mt
= rq
->migration_thread
;
1772 get_task_struct(mt
);
1773 task_rq_unlock(rq
, &flags
);
1774 wake_up_process(mt
);
1775 put_task_struct(mt
);
1776 wait_for_completion(&req
.done
);
1780 task_rq_unlock(rq
, &flags
);
1784 * sched_exec - execve() is a valuable balancing opportunity, because at
1785 * this point the task has the smallest effective memory and cache footprint.
1787 void sched_exec(void)
1789 int new_cpu
, this_cpu
= get_cpu();
1790 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
1792 if (new_cpu
!= this_cpu
)
1793 sched_migrate_task(current
, new_cpu
);
1797 * pull_task - move a task from a remote runqueue to the local runqueue.
1798 * Both runqueues must be locked.
1801 void pull_task(runqueue_t
*src_rq
, prio_array_t
*src_array
, task_t
*p
,
1802 runqueue_t
*this_rq
, prio_array_t
*this_array
, int this_cpu
)
1804 dequeue_task(p
, src_array
);
1805 src_rq
->nr_running
--;
1806 set_task_cpu(p
, this_cpu
);
1807 this_rq
->nr_running
++;
1808 enqueue_task(p
, this_array
);
1809 p
->timestamp
= (p
->timestamp
- src_rq
->timestamp_last_tick
)
1810 + this_rq
->timestamp_last_tick
;
1812 * Note that idle threads have a prio of MAX_PRIO, for this test
1813 * to be always true for them.
1815 if (TASK_PREEMPTS_CURR(p
, this_rq
))
1816 resched_task(this_rq
->curr
);
1820 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1823 int can_migrate_task(task_t
*p
, runqueue_t
*rq
, int this_cpu
,
1824 struct sched_domain
*sd
, enum idle_type idle
,
1828 * We do not migrate tasks that are:
1829 * 1) running (obviously), or
1830 * 2) cannot be migrated to this CPU due to cpus_allowed, or
1831 * 3) are cache-hot on their current CPU.
1833 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
1837 if (task_running(rq
, p
))
1841 * Aggressive migration if:
1842 * 1) task is cache cold, or
1843 * 2) too many balance attempts have failed.
1846 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
)
1849 if (task_hot(p
, rq
->timestamp_last_tick
, sd
))
1855 * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1856 * as part of a balancing operation within "domain". Returns the number of
1859 * Called with both runqueues locked.
1861 static int move_tasks(runqueue_t
*this_rq
, int this_cpu
, runqueue_t
*busiest
,
1862 unsigned long max_nr_move
, struct sched_domain
*sd
,
1863 enum idle_type idle
, int *all_pinned
)
1865 prio_array_t
*array
, *dst_array
;
1866 struct list_head
*head
, *curr
;
1867 int idx
, pulled
= 0, pinned
= 0;
1870 if (max_nr_move
== 0)
1876 * We first consider expired tasks. Those will likely not be
1877 * executed in the near future, and they are most likely to
1878 * be cache-cold, thus switching CPUs has the least effect
1881 if (busiest
->expired
->nr_active
) {
1882 array
= busiest
->expired
;
1883 dst_array
= this_rq
->expired
;
1885 array
= busiest
->active
;
1886 dst_array
= this_rq
->active
;
1890 /* Start searching at priority 0: */
1894 idx
= sched_find_first_bit(array
->bitmap
);
1896 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
1897 if (idx
>= MAX_PRIO
) {
1898 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
1899 array
= busiest
->active
;
1900 dst_array
= this_rq
->active
;
1906 head
= array
->queue
+ idx
;
1909 tmp
= list_entry(curr
, task_t
, run_list
);
1913 if (!can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
1920 #ifdef CONFIG_SCHEDSTATS
1921 if (task_hot(tmp
, busiest
->timestamp_last_tick
, sd
))
1922 schedstat_inc(sd
, lb_hot_gained
[idle
]);
1925 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
1928 /* We only want to steal up to the prescribed number of tasks. */
1929 if (pulled
< max_nr_move
) {
1937 * Right now, this is the only place pull_task() is called,
1938 * so we can safely collect pull_task() stats here rather than
1939 * inside pull_task().
1941 schedstat_add(sd
, lb_gained
[idle
], pulled
);
1944 *all_pinned
= pinned
;
1949 * find_busiest_group finds and returns the busiest CPU group within the
1950 * domain. It calculates and returns the number of tasks which should be
1951 * moved to restore balance via the imbalance parameter.
1953 static struct sched_group
*
1954 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
1955 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
)
1957 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1958 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
1959 unsigned long max_pull
;
1962 max_load
= this_load
= total_load
= total_pwr
= 0;
1963 if (idle
== NOT_IDLE
)
1964 load_idx
= sd
->busy_idx
;
1965 else if (idle
== NEWLY_IDLE
)
1966 load_idx
= sd
->newidle_idx
;
1968 load_idx
= sd
->idle_idx
;
1975 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1977 /* Tally up the load of all CPUs in the group */
1980 for_each_cpu_mask(i
, group
->cpumask
) {
1981 if (*sd_idle
&& !idle_cpu(i
))
1984 /* Bias balancing toward cpus of our domain */
1986 load
= target_load(i
, load_idx
);
1988 load
= source_load(i
, load_idx
);
1993 total_load
+= avg_load
;
1994 total_pwr
+= group
->cpu_power
;
1996 /* Adjust by relative CPU power of the group */
1997 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2000 this_load
= avg_load
;
2002 } else if (avg_load
> max_load
) {
2003 max_load
= avg_load
;
2006 group
= group
->next
;
2007 } while (group
!= sd
->groups
);
2009 if (!busiest
|| this_load
>= max_load
|| max_load
<= SCHED_LOAD_SCALE
)
2012 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2014 if (this_load
>= avg_load
||
2015 100*max_load
<= sd
->imbalance_pct
*this_load
)
2019 * We're trying to get all the cpus to the average_load, so we don't
2020 * want to push ourselves above the average load, nor do we wish to
2021 * reduce the max loaded cpu below the average load, as either of these
2022 * actions would just result in more rebalancing later, and ping-pong
2023 * tasks around. Thus we look for the minimum possible imbalance.
2024 * Negative imbalances (*we* are more loaded than anyone else) will
2025 * be counted as no imbalance for these purposes -- we can't fix that
2026 * by pulling tasks to us. Be careful of negative numbers as they'll
2027 * appear as very large values with unsigned longs.
2030 /* Don't want to pull so many tasks that a group would go idle */
2031 max_pull
= min(max_load
- avg_load
, max_load
- SCHED_LOAD_SCALE
);
2033 /* How much load to actually move to equalise the imbalance */
2034 *imbalance
= min(max_pull
* busiest
->cpu_power
,
2035 (avg_load
- this_load
) * this->cpu_power
)
2038 if (*imbalance
< SCHED_LOAD_SCALE
) {
2039 unsigned long pwr_now
= 0, pwr_move
= 0;
2042 if (max_load
- this_load
>= SCHED_LOAD_SCALE
*2) {
2048 * OK, we don't have enough imbalance to justify moving tasks,
2049 * however we may be able to increase total CPU power used by
2053 pwr_now
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
, max_load
);
2054 pwr_now
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
);
2055 pwr_now
/= SCHED_LOAD_SCALE
;
2057 /* Amount of load we'd subtract */
2058 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/busiest
->cpu_power
;
2060 pwr_move
+= busiest
->cpu_power
*min(SCHED_LOAD_SCALE
,
2063 /* Amount of load we'd add */
2064 if (max_load
*busiest
->cpu_power
<
2065 SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
)
2066 tmp
= max_load
*busiest
->cpu_power
/this->cpu_power
;
2068 tmp
= SCHED_LOAD_SCALE
*SCHED_LOAD_SCALE
/this->cpu_power
;
2069 pwr_move
+= this->cpu_power
*min(SCHED_LOAD_SCALE
, this_load
+ tmp
);
2070 pwr_move
/= SCHED_LOAD_SCALE
;
2072 /* Move if we gain throughput */
2073 if (pwr_move
<= pwr_now
)
2080 /* Get rid of the scaling factor, rounding down as we divide */
2081 *imbalance
= *imbalance
/ SCHED_LOAD_SCALE
;
2091 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2093 static runqueue_t
*find_busiest_queue(struct sched_group
*group
,
2094 enum idle_type idle
)
2096 unsigned long load
, max_load
= 0;
2097 runqueue_t
*busiest
= NULL
;
2100 for_each_cpu_mask(i
, group
->cpumask
) {
2101 load
= source_load(i
, 0);
2103 if (load
> max_load
) {
2105 busiest
= cpu_rq(i
);
2113 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2114 * so long as it is large enough.
2116 #define MAX_PINNED_INTERVAL 512
2119 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2120 * tasks if there is an imbalance.
2122 * Called with this_rq unlocked.
2124 static int load_balance(int this_cpu
, runqueue_t
*this_rq
,
2125 struct sched_domain
*sd
, enum idle_type idle
)
2127 struct sched_group
*group
;
2128 runqueue_t
*busiest
;
2129 unsigned long imbalance
;
2130 int nr_moved
, all_pinned
= 0;
2131 int active_balance
= 0;
2134 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2137 schedstat_inc(sd
, lb_cnt
[idle
]);
2139 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
);
2141 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2145 busiest
= find_busiest_queue(group
, idle
);
2147 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2151 BUG_ON(busiest
== this_rq
);
2153 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2156 if (busiest
->nr_running
> 1) {
2158 * Attempt to move tasks. If find_busiest_group has found
2159 * an imbalance but busiest->nr_running <= 1, the group is
2160 * still unbalanced. nr_moved simply stays zero, so it is
2161 * correctly treated as an imbalance.
2163 double_rq_lock(this_rq
, busiest
);
2164 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2165 imbalance
, sd
, idle
, &all_pinned
);
2166 double_rq_unlock(this_rq
, busiest
);
2168 /* All tasks on this runqueue were pinned by CPU affinity */
2169 if (unlikely(all_pinned
))
2174 schedstat_inc(sd
, lb_failed
[idle
]);
2175 sd
->nr_balance_failed
++;
2177 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2179 spin_lock(&busiest
->lock
);
2181 /* don't kick the migration_thread, if the curr
2182 * task on busiest cpu can't be moved to this_cpu
2184 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2185 spin_unlock(&busiest
->lock
);
2187 goto out_one_pinned
;
2190 if (!busiest
->active_balance
) {
2191 busiest
->active_balance
= 1;
2192 busiest
->push_cpu
= this_cpu
;
2195 spin_unlock(&busiest
->lock
);
2197 wake_up_process(busiest
->migration_thread
);
2200 * We've kicked active balancing, reset the failure
2203 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2206 sd
->nr_balance_failed
= 0;
2208 if (likely(!active_balance
)) {
2209 /* We were unbalanced, so reset the balancing interval */
2210 sd
->balance_interval
= sd
->min_interval
;
2213 * If we've begun active balancing, start to back off. This
2214 * case may not be covered by the all_pinned logic if there
2215 * is only 1 task on the busy runqueue (because we don't call
2218 if (sd
->balance_interval
< sd
->max_interval
)
2219 sd
->balance_interval
*= 2;
2222 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2227 schedstat_inc(sd
, lb_balanced
[idle
]);
2229 sd
->nr_balance_failed
= 0;
2232 /* tune up the balancing interval */
2233 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2234 (sd
->balance_interval
< sd
->max_interval
))
2235 sd
->balance_interval
*= 2;
2237 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2243 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2244 * tasks if there is an imbalance.
2246 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2247 * this_rq is locked.
2249 static int load_balance_newidle(int this_cpu
, runqueue_t
*this_rq
,
2250 struct sched_domain
*sd
)
2252 struct sched_group
*group
;
2253 runqueue_t
*busiest
= NULL
;
2254 unsigned long imbalance
;
2258 if (sd
->flags
& SD_SHARE_CPUPOWER
)
2261 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2262 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
, &sd_idle
);
2264 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2268 busiest
= find_busiest_queue(group
, NEWLY_IDLE
);
2270 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2274 BUG_ON(busiest
== this_rq
);
2276 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2279 if (busiest
->nr_running
> 1) {
2280 /* Attempt to move tasks */
2281 double_lock_balance(this_rq
, busiest
);
2282 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2283 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2284 spin_unlock(&busiest
->lock
);
2288 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2289 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2292 sd
->nr_balance_failed
= 0;
2297 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2298 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
)
2300 sd
->nr_balance_failed
= 0;
2305 * idle_balance is called by schedule() if this_cpu is about to become
2306 * idle. Attempts to pull tasks from other CPUs.
2308 static void idle_balance(int this_cpu
, runqueue_t
*this_rq
)
2310 struct sched_domain
*sd
;
2312 for_each_domain(this_cpu
, sd
) {
2313 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2314 if (load_balance_newidle(this_cpu
, this_rq
, sd
)) {
2315 /* We've pulled tasks over so stop searching */
2323 * active_load_balance is run by migration threads. It pushes running tasks
2324 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2325 * running on each physical CPU where possible, and avoids physical /
2326 * logical imbalances.
2328 * Called with busiest_rq locked.
2330 static void active_load_balance(runqueue_t
*busiest_rq
, int busiest_cpu
)
2332 struct sched_domain
*sd
;
2333 runqueue_t
*target_rq
;
2334 int target_cpu
= busiest_rq
->push_cpu
;
2336 if (busiest_rq
->nr_running
<= 1)
2337 /* no task to move */
2340 target_rq
= cpu_rq(target_cpu
);
2343 * This condition is "impossible", if it occurs
2344 * we need to fix it. Originally reported by
2345 * Bjorn Helgaas on a 128-cpu setup.
2347 BUG_ON(busiest_rq
== target_rq
);
2349 /* move a task from busiest_rq to target_rq */
2350 double_lock_balance(busiest_rq
, target_rq
);
2352 /* Search for an sd spanning us and the target CPU. */
2353 for_each_domain(target_cpu
, sd
) {
2354 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2355 cpu_isset(busiest_cpu
, sd
->span
))
2359 if (unlikely(sd
== NULL
))
2362 schedstat_inc(sd
, alb_cnt
);
2364 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1, sd
, SCHED_IDLE
, NULL
))
2365 schedstat_inc(sd
, alb_pushed
);
2367 schedstat_inc(sd
, alb_failed
);
2369 spin_unlock(&target_rq
->lock
);
2373 * rebalance_tick will get called every timer tick, on every CPU.
2375 * It checks each scheduling domain to see if it is due to be balanced,
2376 * and initiates a balancing operation if so.
2378 * Balancing parameters are set up in arch_init_sched_domains.
2381 /* Don't have all balancing operations going off at once */
2382 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2384 static void rebalance_tick(int this_cpu
, runqueue_t
*this_rq
,
2385 enum idle_type idle
)
2387 unsigned long old_load
, this_load
;
2388 unsigned long j
= jiffies
+ CPU_OFFSET(this_cpu
);
2389 struct sched_domain
*sd
;
2392 this_load
= this_rq
->nr_running
* SCHED_LOAD_SCALE
;
2393 /* Update our load */
2394 for (i
= 0; i
< 3; i
++) {
2395 unsigned long new_load
= this_load
;
2397 old_load
= this_rq
->cpu_load
[i
];
2399 * Round up the averaging division if load is increasing. This
2400 * prevents us from getting stuck on 9 if the load is 10, for
2403 if (new_load
> old_load
)
2404 new_load
+= scale
-1;
2405 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2408 for_each_domain(this_cpu
, sd
) {
2409 unsigned long interval
;
2411 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2414 interval
= sd
->balance_interval
;
2415 if (idle
!= SCHED_IDLE
)
2416 interval
*= sd
->busy_factor
;
2418 /* scale ms to jiffies */
2419 interval
= msecs_to_jiffies(interval
);
2420 if (unlikely(!interval
))
2423 if (j
- sd
->last_balance
>= interval
) {
2424 if (load_balance(this_cpu
, this_rq
, sd
, idle
)) {
2426 * We've pulled tasks over so either we're no
2427 * longer idle, or one of our SMT siblings is
2432 sd
->last_balance
+= interval
;
2438 * on UP we do not need to balance between CPUs:
2440 static inline void rebalance_tick(int cpu
, runqueue_t
*rq
, enum idle_type idle
)
2443 static inline void idle_balance(int cpu
, runqueue_t
*rq
)
2448 static inline int wake_priority_sleeper(runqueue_t
*rq
)
2451 #ifdef CONFIG_SCHED_SMT
2452 spin_lock(&rq
->lock
);
2454 * If an SMT sibling task has been put to sleep for priority
2455 * reasons reschedule the idle task to see if it can now run.
2457 if (rq
->nr_running
) {
2458 resched_task(rq
->idle
);
2461 spin_unlock(&rq
->lock
);
2466 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
2468 EXPORT_PER_CPU_SYMBOL(kstat
);
2471 * This is called on clock ticks and on context switches.
2472 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2474 static inline void update_cpu_clock(task_t
*p
, runqueue_t
*rq
,
2475 unsigned long long now
)
2477 unsigned long long last
= max(p
->timestamp
, rq
->timestamp_last_tick
);
2478 p
->sched_time
+= now
- last
;
2482 * Return current->sched_time plus any more ns on the sched_clock
2483 * that have not yet been banked.
2485 unsigned long long current_sched_time(const task_t
*tsk
)
2487 unsigned long long ns
;
2488 unsigned long flags
;
2489 local_irq_save(flags
);
2490 ns
= max(tsk
->timestamp
, task_rq(tsk
)->timestamp_last_tick
);
2491 ns
= tsk
->sched_time
+ (sched_clock() - ns
);
2492 local_irq_restore(flags
);
2497 * We place interactive tasks back into the active array, if possible.
2499 * To guarantee that this does not starve expired tasks we ignore the
2500 * interactivity of a task if the first expired task had to wait more
2501 * than a 'reasonable' amount of time. This deadline timeout is
2502 * load-dependent, as the frequency of array switched decreases with
2503 * increasing number of running tasks. We also ignore the interactivity
2504 * if a better static_prio task has expired:
2506 #define EXPIRED_STARVING(rq) \
2507 ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2508 (jiffies - (rq)->expired_timestamp >= \
2509 STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2510 ((rq)->curr->static_prio > (rq)->best_expired_prio))
2513 * Account user cpu time to a process.
2514 * @p: the process that the cpu time gets accounted to
2515 * @hardirq_offset: the offset to subtract from hardirq_count()
2516 * @cputime: the cpu time spent in user space since the last update
2518 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
2520 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2523 p
->utime
= cputime_add(p
->utime
, cputime
);
2525 /* Add user time to cpustat. */
2526 tmp
= cputime_to_cputime64(cputime
);
2527 if (TASK_NICE(p
) > 0)
2528 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
2530 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
2534 * Account system cpu time to a process.
2535 * @p: the process that the cpu time gets accounted to
2536 * @hardirq_offset: the offset to subtract from hardirq_count()
2537 * @cputime: the cpu time spent in kernel space since the last update
2539 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
2542 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2543 runqueue_t
*rq
= this_rq();
2546 p
->stime
= cputime_add(p
->stime
, cputime
);
2548 /* Add system time to cpustat. */
2549 tmp
= cputime_to_cputime64(cputime
);
2550 if (hardirq_count() - hardirq_offset
)
2551 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
2552 else if (softirq_count())
2553 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
2554 else if (p
!= rq
->idle
)
2555 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
2556 else if (atomic_read(&rq
->nr_iowait
) > 0)
2557 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2559 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2560 /* Account for system time used */
2561 acct_update_integrals(p
);
2565 * Account for involuntary wait time.
2566 * @p: the process from which the cpu time has been stolen
2567 * @steal: the cpu time spent in involuntary wait
2569 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
2571 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
2572 cputime64_t tmp
= cputime_to_cputime64(steal
);
2573 runqueue_t
*rq
= this_rq();
2575 if (p
== rq
->idle
) {
2576 p
->stime
= cputime_add(p
->stime
, steal
);
2577 if (atomic_read(&rq
->nr_iowait
) > 0)
2578 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
2580 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
2582 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
2586 * This function gets called by the timer code, with HZ frequency.
2587 * We call it with interrupts disabled.
2589 * It also gets called by the fork code, when changing the parent's
2592 void scheduler_tick(void)
2594 int cpu
= smp_processor_id();
2595 runqueue_t
*rq
= this_rq();
2596 task_t
*p
= current
;
2597 unsigned long long now
= sched_clock();
2599 update_cpu_clock(p
, rq
, now
);
2601 rq
->timestamp_last_tick
= now
;
2603 if (p
== rq
->idle
) {
2604 if (wake_priority_sleeper(rq
))
2606 rebalance_tick(cpu
, rq
, SCHED_IDLE
);
2610 /* Task might have expired already, but not scheduled off yet */
2611 if (p
->array
!= rq
->active
) {
2612 set_tsk_need_resched(p
);
2615 spin_lock(&rq
->lock
);
2617 * The task was running during this tick - update the
2618 * time slice counter. Note: we do not update a thread's
2619 * priority until it either goes to sleep or uses up its
2620 * timeslice. This makes it possible for interactive tasks
2621 * to use up their timeslices at their highest priority levels.
2625 * RR tasks need a special form of timeslice management.
2626 * FIFO tasks have no timeslices.
2628 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
2629 p
->time_slice
= task_timeslice(p
);
2630 p
->first_time_slice
= 0;
2631 set_tsk_need_resched(p
);
2633 /* put it at the end of the queue: */
2634 requeue_task(p
, rq
->active
);
2638 if (!--p
->time_slice
) {
2639 dequeue_task(p
, rq
->active
);
2640 set_tsk_need_resched(p
);
2641 p
->prio
= effective_prio(p
);
2642 p
->time_slice
= task_timeslice(p
);
2643 p
->first_time_slice
= 0;
2645 if (!rq
->expired_timestamp
)
2646 rq
->expired_timestamp
= jiffies
;
2647 if (!TASK_INTERACTIVE(p
) || EXPIRED_STARVING(rq
)) {
2648 enqueue_task(p
, rq
->expired
);
2649 if (p
->static_prio
< rq
->best_expired_prio
)
2650 rq
->best_expired_prio
= p
->static_prio
;
2652 enqueue_task(p
, rq
->active
);
2655 * Prevent a too long timeslice allowing a task to monopolize
2656 * the CPU. We do this by splitting up the timeslice into
2659 * Note: this does not mean the task's timeslices expire or
2660 * get lost in any way, they just might be preempted by
2661 * another task of equal priority. (one with higher
2662 * priority would have preempted this task already.) We
2663 * requeue this task to the end of the list on this priority
2664 * level, which is in essence a round-robin of tasks with
2667 * This only applies to tasks in the interactive
2668 * delta range with at least TIMESLICE_GRANULARITY to requeue.
2670 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
2671 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
2672 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
2673 (p
->array
== rq
->active
)) {
2675 requeue_task(p
, rq
->active
);
2676 set_tsk_need_resched(p
);
2680 spin_unlock(&rq
->lock
);
2682 rebalance_tick(cpu
, rq
, NOT_IDLE
);
2685 #ifdef CONFIG_SCHED_SMT
2686 static inline void wakeup_busy_runqueue(runqueue_t
*rq
)
2688 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
2689 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
2690 resched_task(rq
->idle
);
2694 * Called with interrupt disabled and this_rq's runqueue locked.
2696 static void wake_sleeping_dependent(int this_cpu
)
2698 struct sched_domain
*tmp
, *sd
= NULL
;
2701 for_each_domain(this_cpu
, tmp
) {
2702 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
2711 for_each_cpu_mask(i
, sd
->span
) {
2712 runqueue_t
*smt_rq
= cpu_rq(i
);
2716 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
2719 wakeup_busy_runqueue(smt_rq
);
2720 spin_unlock(&smt_rq
->lock
);
2725 * number of 'lost' timeslices this task wont be able to fully
2726 * utilize, if another task runs on a sibling. This models the
2727 * slowdown effect of other tasks running on siblings:
2729 static inline unsigned long smt_slice(task_t
*p
, struct sched_domain
*sd
)
2731 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
2735 * To minimise lock contention and not have to drop this_rq's runlock we only
2736 * trylock the sibling runqueues and bypass those runqueues if we fail to
2737 * acquire their lock. As we only trylock the normal locking order does not
2738 * need to be obeyed.
2740 static int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
, task_t
*p
)
2742 struct sched_domain
*tmp
, *sd
= NULL
;
2745 /* kernel/rt threads do not participate in dependent sleeping */
2746 if (!p
->mm
|| rt_task(p
))
2749 for_each_domain(this_cpu
, tmp
) {
2750 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
2759 for_each_cpu_mask(i
, sd
->span
) {
2767 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
2770 smt_curr
= smt_rq
->curr
;
2776 * If a user task with lower static priority than the
2777 * running task on the SMT sibling is trying to schedule,
2778 * delay it till there is proportionately less timeslice
2779 * left of the sibling task to prevent a lower priority
2780 * task from using an unfair proportion of the
2781 * physical cpu's resources. -ck
2783 if (rt_task(smt_curr
)) {
2785 * With real time tasks we run non-rt tasks only
2786 * per_cpu_gain% of the time.
2788 if ((jiffies
% DEF_TIMESLICE
) >
2789 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
2792 if (smt_curr
->static_prio
< p
->static_prio
&&
2793 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
2794 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
2798 spin_unlock(&smt_rq
->lock
);
2803 static inline void wake_sleeping_dependent(int this_cpu
)
2807 static inline int dependent_sleeper(int this_cpu
, runqueue_t
*this_rq
,
2814 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2816 void fastcall
add_preempt_count(int val
)
2821 BUG_ON((preempt_count() < 0));
2822 preempt_count() += val
;
2824 * Spinlock count overflowing soon?
2826 BUG_ON((preempt_count() & PREEMPT_MASK
) >= PREEMPT_MASK
-10);
2828 EXPORT_SYMBOL(add_preempt_count
);
2830 void fastcall
sub_preempt_count(int val
)
2835 BUG_ON(val
> preempt_count());
2837 * Is the spinlock portion underflowing?
2839 BUG_ON((val
< PREEMPT_MASK
) && !(preempt_count() & PREEMPT_MASK
));
2840 preempt_count() -= val
;
2842 EXPORT_SYMBOL(sub_preempt_count
);
2846 static inline int interactive_sleep(enum sleep_type sleep_type
)
2848 return (sleep_type
== SLEEP_INTERACTIVE
||
2849 sleep_type
== SLEEP_INTERRUPTED
);
2853 * schedule() is the main scheduler function.
2855 asmlinkage
void __sched
schedule(void)
2858 task_t
*prev
, *next
;
2860 prio_array_t
*array
;
2861 struct list_head
*queue
;
2862 unsigned long long now
;
2863 unsigned long run_time
;
2864 int cpu
, idx
, new_prio
;
2867 * Test if we are atomic. Since do_exit() needs to call into
2868 * schedule() atomically, we ignore that path for now.
2869 * Otherwise, whine if we are scheduling when we should not be.
2871 if (unlikely(in_atomic() && !current
->exit_state
)) {
2872 printk(KERN_ERR
"BUG: scheduling while atomic: "
2874 current
->comm
, preempt_count(), current
->pid
);
2877 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
2882 release_kernel_lock(prev
);
2883 need_resched_nonpreemptible
:
2887 * The idle thread is not allowed to schedule!
2888 * Remove this check after it has been exercised a bit.
2890 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
2891 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
2895 schedstat_inc(rq
, sched_cnt
);
2896 now
= sched_clock();
2897 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
2898 run_time
= now
- prev
->timestamp
;
2899 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
2902 run_time
= NS_MAX_SLEEP_AVG
;
2905 * Tasks charged proportionately less run_time at high sleep_avg to
2906 * delay them losing their interactive status
2908 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
2910 spin_lock_irq(&rq
->lock
);
2912 if (unlikely(prev
->flags
& PF_DEAD
))
2913 prev
->state
= EXIT_DEAD
;
2915 switch_count
= &prev
->nivcsw
;
2916 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
2917 switch_count
= &prev
->nvcsw
;
2918 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
2919 unlikely(signal_pending(prev
))))
2920 prev
->state
= TASK_RUNNING
;
2922 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
2923 rq
->nr_uninterruptible
++;
2924 deactivate_task(prev
, rq
);
2928 cpu
= smp_processor_id();
2929 if (unlikely(!rq
->nr_running
)) {
2930 idle_balance(cpu
, rq
);
2931 if (!rq
->nr_running
) {
2933 rq
->expired_timestamp
= 0;
2934 wake_sleeping_dependent(cpu
);
2940 if (unlikely(!array
->nr_active
)) {
2942 * Switch the active and expired arrays.
2944 schedstat_inc(rq
, sched_switch
);
2945 rq
->active
= rq
->expired
;
2946 rq
->expired
= array
;
2948 rq
->expired_timestamp
= 0;
2949 rq
->best_expired_prio
= MAX_PRIO
;
2952 idx
= sched_find_first_bit(array
->bitmap
);
2953 queue
= array
->queue
+ idx
;
2954 next
= list_entry(queue
->next
, task_t
, run_list
);
2956 if (!rt_task(next
) && interactive_sleep(next
->sleep_type
)) {
2957 unsigned long long delta
= now
- next
->timestamp
;
2958 if (unlikely((long long)(now
- next
->timestamp
) < 0))
2961 if (next
->sleep_type
== SLEEP_INTERACTIVE
)
2962 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
2964 array
= next
->array
;
2965 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
2967 if (unlikely(next
->prio
!= new_prio
)) {
2968 dequeue_task(next
, array
);
2969 next
->prio
= new_prio
;
2970 enqueue_task(next
, array
);
2973 next
->sleep_type
= SLEEP_NORMAL
;
2974 if (dependent_sleeper(cpu
, rq
, next
))
2977 if (next
== rq
->idle
)
2978 schedstat_inc(rq
, sched_goidle
);
2980 prefetch_stack(next
);
2981 clear_tsk_need_resched(prev
);
2982 rcu_qsctr_inc(task_cpu(prev
));
2984 update_cpu_clock(prev
, rq
, now
);
2986 prev
->sleep_avg
-= run_time
;
2987 if ((long)prev
->sleep_avg
<= 0)
2988 prev
->sleep_avg
= 0;
2989 prev
->timestamp
= prev
->last_ran
= now
;
2991 sched_info_switch(prev
, next
);
2992 if (likely(prev
!= next
)) {
2993 next
->timestamp
= now
;
2998 prepare_task_switch(rq
, next
);
2999 prev
= context_switch(rq
, prev
, next
);
3002 * this_rq must be evaluated again because prev may have moved
3003 * CPUs since it called schedule(), thus the 'rq' on its stack
3004 * frame will be invalid.
3006 finish_task_switch(this_rq(), prev
);
3008 spin_unlock_irq(&rq
->lock
);
3011 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3012 goto need_resched_nonpreemptible
;
3013 preempt_enable_no_resched();
3014 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3018 EXPORT_SYMBOL(schedule
);
3020 #ifdef CONFIG_PREEMPT
3022 * this is is the entry point to schedule() from in-kernel preemption
3023 * off of preempt_enable. Kernel preemptions off return from interrupt
3024 * occur there and call schedule directly.
3026 asmlinkage
void __sched
preempt_schedule(void)
3028 struct thread_info
*ti
= current_thread_info();
3029 #ifdef CONFIG_PREEMPT_BKL
3030 struct task_struct
*task
= current
;
3031 int saved_lock_depth
;
3034 * If there is a non-zero preempt_count or interrupts are disabled,
3035 * we do not want to preempt the current task. Just return..
3037 if (unlikely(ti
->preempt_count
|| irqs_disabled()))
3041 add_preempt_count(PREEMPT_ACTIVE
);
3043 * We keep the big kernel semaphore locked, but we
3044 * clear ->lock_depth so that schedule() doesnt
3045 * auto-release the semaphore:
3047 #ifdef CONFIG_PREEMPT_BKL
3048 saved_lock_depth
= task
->lock_depth
;
3049 task
->lock_depth
= -1;
3052 #ifdef CONFIG_PREEMPT_BKL
3053 task
->lock_depth
= saved_lock_depth
;
3055 sub_preempt_count(PREEMPT_ACTIVE
);
3057 /* we could miss a preemption opportunity between schedule and now */
3059 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3063 EXPORT_SYMBOL(preempt_schedule
);
3066 * this is is the entry point to schedule() from kernel preemption
3067 * off of irq context.
3068 * Note, that this is called and return with irqs disabled. This will
3069 * protect us against recursive calling from irq.
3071 asmlinkage
void __sched
preempt_schedule_irq(void)
3073 struct thread_info
*ti
= current_thread_info();
3074 #ifdef CONFIG_PREEMPT_BKL
3075 struct task_struct
*task
= current
;
3076 int saved_lock_depth
;
3078 /* Catch callers which need to be fixed*/
3079 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3082 add_preempt_count(PREEMPT_ACTIVE
);
3084 * We keep the big kernel semaphore locked, but we
3085 * clear ->lock_depth so that schedule() doesnt
3086 * auto-release the semaphore:
3088 #ifdef CONFIG_PREEMPT_BKL
3089 saved_lock_depth
= task
->lock_depth
;
3090 task
->lock_depth
= -1;
3094 local_irq_disable();
3095 #ifdef CONFIG_PREEMPT_BKL
3096 task
->lock_depth
= saved_lock_depth
;
3098 sub_preempt_count(PREEMPT_ACTIVE
);
3100 /* we could miss a preemption opportunity between schedule and now */
3102 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3106 #endif /* CONFIG_PREEMPT */
3108 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3111 task_t
*p
= curr
->private;
3112 return try_to_wake_up(p
, mode
, sync
);
3115 EXPORT_SYMBOL(default_wake_function
);
3118 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3119 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3120 * number) then we wake all the non-exclusive tasks and one exclusive task.
3122 * There are circumstances in which we can try to wake a task which has already
3123 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3124 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3126 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3127 int nr_exclusive
, int sync
, void *key
)
3129 struct list_head
*tmp
, *next
;
3131 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3134 curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3135 flags
= curr
->flags
;
3136 if (curr
->func(curr
, mode
, sync
, key
) &&
3137 (flags
& WQ_FLAG_EXCLUSIVE
) &&
3144 * __wake_up - wake up threads blocked on a waitqueue.
3146 * @mode: which threads
3147 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3148 * @key: is directly passed to the wakeup function
3150 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3151 int nr_exclusive
, void *key
)
3153 unsigned long flags
;
3155 spin_lock_irqsave(&q
->lock
, flags
);
3156 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3157 spin_unlock_irqrestore(&q
->lock
, flags
);
3160 EXPORT_SYMBOL(__wake_up
);
3163 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3165 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3167 __wake_up_common(q
, mode
, 1, 0, NULL
);
3171 * __wake_up_sync - wake up threads blocked on a waitqueue.
3173 * @mode: which threads
3174 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3176 * The sync wakeup differs that the waker knows that it will schedule
3177 * away soon, so while the target thread will be woken up, it will not
3178 * be migrated to another CPU - ie. the two threads are 'synchronized'
3179 * with each other. This can prevent needless bouncing between CPUs.
3181 * On UP it can prevent extra preemption.
3184 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3186 unsigned long flags
;
3192 if (unlikely(!nr_exclusive
))
3195 spin_lock_irqsave(&q
->lock
, flags
);
3196 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3197 spin_unlock_irqrestore(&q
->lock
, flags
);
3199 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3201 void fastcall
complete(struct completion
*x
)
3203 unsigned long flags
;
3205 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3207 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3209 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3211 EXPORT_SYMBOL(complete
);
3213 void fastcall
complete_all(struct completion
*x
)
3215 unsigned long flags
;
3217 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3218 x
->done
+= UINT_MAX
/2;
3219 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3221 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3223 EXPORT_SYMBOL(complete_all
);
3225 void fastcall __sched
wait_for_completion(struct completion
*x
)
3228 spin_lock_irq(&x
->wait
.lock
);
3230 DECLARE_WAITQUEUE(wait
, current
);
3232 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3233 __add_wait_queue_tail(&x
->wait
, &wait
);
3235 __set_current_state(TASK_UNINTERRUPTIBLE
);
3236 spin_unlock_irq(&x
->wait
.lock
);
3238 spin_lock_irq(&x
->wait
.lock
);
3240 __remove_wait_queue(&x
->wait
, &wait
);
3243 spin_unlock_irq(&x
->wait
.lock
);
3245 EXPORT_SYMBOL(wait_for_completion
);
3247 unsigned long fastcall __sched
3248 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3252 spin_lock_irq(&x
->wait
.lock
);
3254 DECLARE_WAITQUEUE(wait
, current
);
3256 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3257 __add_wait_queue_tail(&x
->wait
, &wait
);
3259 __set_current_state(TASK_UNINTERRUPTIBLE
);
3260 spin_unlock_irq(&x
->wait
.lock
);
3261 timeout
= schedule_timeout(timeout
);
3262 spin_lock_irq(&x
->wait
.lock
);
3264 __remove_wait_queue(&x
->wait
, &wait
);
3268 __remove_wait_queue(&x
->wait
, &wait
);
3272 spin_unlock_irq(&x
->wait
.lock
);
3275 EXPORT_SYMBOL(wait_for_completion_timeout
);
3277 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3283 spin_lock_irq(&x
->wait
.lock
);
3285 DECLARE_WAITQUEUE(wait
, current
);
3287 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3288 __add_wait_queue_tail(&x
->wait
, &wait
);
3290 if (signal_pending(current
)) {
3292 __remove_wait_queue(&x
->wait
, &wait
);
3295 __set_current_state(TASK_INTERRUPTIBLE
);
3296 spin_unlock_irq(&x
->wait
.lock
);
3298 spin_lock_irq(&x
->wait
.lock
);
3300 __remove_wait_queue(&x
->wait
, &wait
);
3304 spin_unlock_irq(&x
->wait
.lock
);
3308 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3310 unsigned long fastcall __sched
3311 wait_for_completion_interruptible_timeout(struct completion
*x
,
3312 unsigned long timeout
)
3316 spin_lock_irq(&x
->wait
.lock
);
3318 DECLARE_WAITQUEUE(wait
, current
);
3320 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3321 __add_wait_queue_tail(&x
->wait
, &wait
);
3323 if (signal_pending(current
)) {
3324 timeout
= -ERESTARTSYS
;
3325 __remove_wait_queue(&x
->wait
, &wait
);
3328 __set_current_state(TASK_INTERRUPTIBLE
);
3329 spin_unlock_irq(&x
->wait
.lock
);
3330 timeout
= schedule_timeout(timeout
);
3331 spin_lock_irq(&x
->wait
.lock
);
3333 __remove_wait_queue(&x
->wait
, &wait
);
3337 __remove_wait_queue(&x
->wait
, &wait
);
3341 spin_unlock_irq(&x
->wait
.lock
);
3344 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3347 #define SLEEP_ON_VAR \
3348 unsigned long flags; \
3349 wait_queue_t wait; \
3350 init_waitqueue_entry(&wait, current);
3352 #define SLEEP_ON_HEAD \
3353 spin_lock_irqsave(&q->lock,flags); \
3354 __add_wait_queue(q, &wait); \
3355 spin_unlock(&q->lock);
3357 #define SLEEP_ON_TAIL \
3358 spin_lock_irq(&q->lock); \
3359 __remove_wait_queue(q, &wait); \
3360 spin_unlock_irqrestore(&q->lock, flags);
3362 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3366 current
->state
= TASK_INTERRUPTIBLE
;
3373 EXPORT_SYMBOL(interruptible_sleep_on
);
3375 long fastcall __sched
3376 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3380 current
->state
= TASK_INTERRUPTIBLE
;
3383 timeout
= schedule_timeout(timeout
);
3389 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3391 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3395 current
->state
= TASK_UNINTERRUPTIBLE
;
3402 EXPORT_SYMBOL(sleep_on
);
3404 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3408 current
->state
= TASK_UNINTERRUPTIBLE
;
3411 timeout
= schedule_timeout(timeout
);
3417 EXPORT_SYMBOL(sleep_on_timeout
);
3419 void set_user_nice(task_t
*p
, long nice
)
3421 unsigned long flags
;
3422 prio_array_t
*array
;
3424 int old_prio
, new_prio
, delta
;
3426 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
3429 * We have to be careful, if called from sys_setpriority(),
3430 * the task might be in the middle of scheduling on another CPU.
3432 rq
= task_rq_lock(p
, &flags
);
3434 * The RT priorities are set via sched_setscheduler(), but we still
3435 * allow the 'normal' nice value to be set - but as expected
3436 * it wont have any effect on scheduling until the task is
3437 * not SCHED_NORMAL/SCHED_BATCH:
3440 p
->static_prio
= NICE_TO_PRIO(nice
);
3445 dequeue_task(p
, array
);
3448 new_prio
= NICE_TO_PRIO(nice
);
3449 delta
= new_prio
- old_prio
;
3450 p
->static_prio
= NICE_TO_PRIO(nice
);
3454 enqueue_task(p
, array
);
3456 * If the task increased its priority or is running and
3457 * lowered its priority, then reschedule its CPU:
3459 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
3460 resched_task(rq
->curr
);
3463 task_rq_unlock(rq
, &flags
);
3466 EXPORT_SYMBOL(set_user_nice
);
3469 * can_nice - check if a task can reduce its nice value
3473 int can_nice(const task_t
*p
, const int nice
)
3475 /* convert nice value [19,-20] to rlimit style value [1,40] */
3476 int nice_rlim
= 20 - nice
;
3477 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
3478 capable(CAP_SYS_NICE
));
3481 #ifdef __ARCH_WANT_SYS_NICE
3484 * sys_nice - change the priority of the current process.
3485 * @increment: priority increment
3487 * sys_setpriority is a more generic, but much slower function that
3488 * does similar things.
3490 asmlinkage
long sys_nice(int increment
)
3496 * Setpriority might change our priority at the same moment.
3497 * We don't have to worry. Conceptually one call occurs first
3498 * and we have a single winner.
3500 if (increment
< -40)
3505 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
3511 if (increment
< 0 && !can_nice(current
, nice
))
3514 retval
= security_task_setnice(current
, nice
);
3518 set_user_nice(current
, nice
);
3525 * task_prio - return the priority value of a given task.
3526 * @p: the task in question.
3528 * This is the priority value as seen by users in /proc.
3529 * RT tasks are offset by -200. Normal tasks are centered
3530 * around 0, value goes from -16 to +15.
3532 int task_prio(const task_t
*p
)
3534 return p
->prio
- MAX_RT_PRIO
;
3538 * task_nice - return the nice value of a given task.
3539 * @p: the task in question.
3541 int task_nice(const task_t
*p
)
3543 return TASK_NICE(p
);
3545 EXPORT_SYMBOL_GPL(task_nice
);
3548 * idle_cpu - is a given cpu idle currently?
3549 * @cpu: the processor in question.
3551 int idle_cpu(int cpu
)
3553 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
3557 * idle_task - return the idle task for a given cpu.
3558 * @cpu: the processor in question.
3560 task_t
*idle_task(int cpu
)
3562 return cpu_rq(cpu
)->idle
;
3566 * find_process_by_pid - find a process with a matching PID value.
3567 * @pid: the pid in question.
3569 static inline task_t
*find_process_by_pid(pid_t pid
)
3571 return pid
? find_task_by_pid(pid
) : current
;
3574 /* Actually do priority change: must hold rq lock. */
3575 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
3579 p
->rt_priority
= prio
;
3580 if (policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
) {
3581 p
->prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
3583 p
->prio
= p
->static_prio
;
3585 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
3587 if (policy
== SCHED_BATCH
)
3593 * sched_setscheduler - change the scheduling policy and/or RT priority of
3595 * @p: the task in question.
3596 * @policy: new policy.
3597 * @param: structure containing the new RT priority.
3599 int sched_setscheduler(struct task_struct
*p
, int policy
,
3600 struct sched_param
*param
)
3603 int oldprio
, oldpolicy
= -1;
3604 prio_array_t
*array
;
3605 unsigned long flags
;
3609 /* double check policy once rq lock held */
3611 policy
= oldpolicy
= p
->policy
;
3612 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
3613 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
)
3616 * Valid priorities for SCHED_FIFO and SCHED_RR are
3617 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
3620 if (param
->sched_priority
< 0 ||
3621 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
3622 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
3624 if ((policy
== SCHED_NORMAL
|| policy
== SCHED_BATCH
)
3625 != (param
->sched_priority
== 0))
3629 * Allow unprivileged RT tasks to decrease priority:
3631 if (!capable(CAP_SYS_NICE
)) {
3633 * can't change policy, except between SCHED_NORMAL
3636 if (((policy
!= SCHED_NORMAL
&& p
->policy
!= SCHED_BATCH
) &&
3637 (policy
!= SCHED_BATCH
&& p
->policy
!= SCHED_NORMAL
)) &&
3638 !p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3640 /* can't increase priority */
3641 if ((policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
) &&
3642 param
->sched_priority
> p
->rt_priority
&&
3643 param
->sched_priority
>
3644 p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
)
3646 /* can't change other user's priorities */
3647 if ((current
->euid
!= p
->euid
) &&
3648 (current
->euid
!= p
->uid
))
3652 retval
= security_task_setscheduler(p
, policy
, param
);
3656 * To be able to change p->policy safely, the apropriate
3657 * runqueue lock must be held.
3659 rq
= task_rq_lock(p
, &flags
);
3660 /* recheck policy now with rq lock held */
3661 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
3662 policy
= oldpolicy
= -1;
3663 task_rq_unlock(rq
, &flags
);
3668 deactivate_task(p
, rq
);
3670 __setscheduler(p
, policy
, param
->sched_priority
);
3672 __activate_task(p
, rq
);
3674 * Reschedule if we are currently running on this runqueue and
3675 * our priority decreased, or if we are not currently running on
3676 * this runqueue and our priority is higher than the current's
3678 if (task_running(rq
, p
)) {
3679 if (p
->prio
> oldprio
)
3680 resched_task(rq
->curr
);
3681 } else if (TASK_PREEMPTS_CURR(p
, rq
))
3682 resched_task(rq
->curr
);
3684 task_rq_unlock(rq
, &flags
);
3687 EXPORT_SYMBOL_GPL(sched_setscheduler
);
3690 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
3693 struct sched_param lparam
;
3694 struct task_struct
*p
;
3696 if (!param
|| pid
< 0)
3698 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
3700 read_lock_irq(&tasklist_lock
);
3701 p
= find_process_by_pid(pid
);
3703 read_unlock_irq(&tasklist_lock
);
3706 retval
= sched_setscheduler(p
, policy
, &lparam
);
3707 read_unlock_irq(&tasklist_lock
);
3712 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3713 * @pid: the pid in question.
3714 * @policy: new policy.
3715 * @param: structure containing the new RT priority.
3717 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
3718 struct sched_param __user
*param
)
3720 /* negative values for policy are not valid */
3724 return do_sched_setscheduler(pid
, policy
, param
);
3728 * sys_sched_setparam - set/change the RT priority of a thread
3729 * @pid: the pid in question.
3730 * @param: structure containing the new RT priority.
3732 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
3734 return do_sched_setscheduler(pid
, -1, param
);
3738 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3739 * @pid: the pid in question.
3741 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
3743 int retval
= -EINVAL
;
3750 read_lock(&tasklist_lock
);
3751 p
= find_process_by_pid(pid
);
3753 retval
= security_task_getscheduler(p
);
3757 read_unlock(&tasklist_lock
);
3764 * sys_sched_getscheduler - get the RT priority of a thread
3765 * @pid: the pid in question.
3766 * @param: structure containing the RT priority.
3768 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
3770 struct sched_param lp
;
3771 int retval
= -EINVAL
;
3774 if (!param
|| pid
< 0)
3777 read_lock(&tasklist_lock
);
3778 p
= find_process_by_pid(pid
);
3783 retval
= security_task_getscheduler(p
);
3787 lp
.sched_priority
= p
->rt_priority
;
3788 read_unlock(&tasklist_lock
);
3791 * This one might sleep, we cannot do it with a spinlock held ...
3793 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
3799 read_unlock(&tasklist_lock
);
3803 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
3807 cpumask_t cpus_allowed
;
3810 read_lock(&tasklist_lock
);
3812 p
= find_process_by_pid(pid
);
3814 read_unlock(&tasklist_lock
);
3815 unlock_cpu_hotplug();
3820 * It is not safe to call set_cpus_allowed with the
3821 * tasklist_lock held. We will bump the task_struct's
3822 * usage count and then drop tasklist_lock.
3825 read_unlock(&tasklist_lock
);
3828 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
3829 !capable(CAP_SYS_NICE
))
3832 retval
= security_task_setscheduler(p
, 0, NULL
);
3836 cpus_allowed
= cpuset_cpus_allowed(p
);
3837 cpus_and(new_mask
, new_mask
, cpus_allowed
);
3838 retval
= set_cpus_allowed(p
, new_mask
);
3842 unlock_cpu_hotplug();
3846 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
3847 cpumask_t
*new_mask
)
3849 if (len
< sizeof(cpumask_t
)) {
3850 memset(new_mask
, 0, sizeof(cpumask_t
));
3851 } else if (len
> sizeof(cpumask_t
)) {
3852 len
= sizeof(cpumask_t
);
3854 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
3858 * sys_sched_setaffinity - set the cpu affinity of a process
3859 * @pid: pid of the process
3860 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3861 * @user_mask_ptr: user-space pointer to the new cpu mask
3863 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
3864 unsigned long __user
*user_mask_ptr
)
3869 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
3873 return sched_setaffinity(pid
, new_mask
);
3877 * Represents all cpu's present in the system
3878 * In systems capable of hotplug, this map could dynamically grow
3879 * as new cpu's are detected in the system via any platform specific
3880 * method, such as ACPI for e.g.
3883 cpumask_t cpu_present_map __read_mostly
;
3884 EXPORT_SYMBOL(cpu_present_map
);
3887 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
3888 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
3891 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
3897 read_lock(&tasklist_lock
);
3900 p
= find_process_by_pid(pid
);
3904 retval
= security_task_getscheduler(p
);
3908 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
3911 read_unlock(&tasklist_lock
);
3912 unlock_cpu_hotplug();
3920 * sys_sched_getaffinity - get the cpu affinity of a process
3921 * @pid: pid of the process
3922 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3923 * @user_mask_ptr: user-space pointer to hold the current cpu mask
3925 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
3926 unsigned long __user
*user_mask_ptr
)
3931 if (len
< sizeof(cpumask_t
))
3934 ret
= sched_getaffinity(pid
, &mask
);
3938 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
3941 return sizeof(cpumask_t
);
3945 * sys_sched_yield - yield the current processor to other threads.
3947 * this function yields the current CPU by moving the calling thread
3948 * to the expired array. If there are no other threads running on this
3949 * CPU then this function will return.
3951 asmlinkage
long sys_sched_yield(void)
3953 runqueue_t
*rq
= this_rq_lock();
3954 prio_array_t
*array
= current
->array
;
3955 prio_array_t
*target
= rq
->expired
;
3957 schedstat_inc(rq
, yld_cnt
);
3959 * We implement yielding by moving the task into the expired
3962 * (special rule: RT tasks will just roundrobin in the active
3965 if (rt_task(current
))
3966 target
= rq
->active
;
3968 if (array
->nr_active
== 1) {
3969 schedstat_inc(rq
, yld_act_empty
);
3970 if (!rq
->expired
->nr_active
)
3971 schedstat_inc(rq
, yld_both_empty
);
3972 } else if (!rq
->expired
->nr_active
)
3973 schedstat_inc(rq
, yld_exp_empty
);
3975 if (array
!= target
) {
3976 dequeue_task(current
, array
);
3977 enqueue_task(current
, target
);
3980 * requeue_task is cheaper so perform that if possible.
3982 requeue_task(current
, array
);
3985 * Since we are going to call schedule() anyway, there's
3986 * no need to preempt or enable interrupts:
3988 __release(rq
->lock
);
3989 _raw_spin_unlock(&rq
->lock
);
3990 preempt_enable_no_resched();
3997 static inline void __cond_resched(void)
3999 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4000 __might_sleep(__FILE__
, __LINE__
);
4003 * The BKS might be reacquired before we have dropped
4004 * PREEMPT_ACTIVE, which could trigger a second
4005 * cond_resched() call.
4007 if (unlikely(preempt_count()))
4009 if (unlikely(system_state
!= SYSTEM_RUNNING
))
4012 add_preempt_count(PREEMPT_ACTIVE
);
4014 sub_preempt_count(PREEMPT_ACTIVE
);
4015 } while (need_resched());
4018 int __sched
cond_resched(void)
4020 if (need_resched()) {
4027 EXPORT_SYMBOL(cond_resched
);
4030 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4031 * call schedule, and on return reacquire the lock.
4033 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4034 * operations here to prevent schedule() from being called twice (once via
4035 * spin_unlock(), once by hand).
4037 int cond_resched_lock(spinlock_t
*lock
)
4041 if (need_lockbreak(lock
)) {
4047 if (need_resched()) {
4048 _raw_spin_unlock(lock
);
4049 preempt_enable_no_resched();
4057 EXPORT_SYMBOL(cond_resched_lock
);
4059 int __sched
cond_resched_softirq(void)
4061 BUG_ON(!in_softirq());
4063 if (need_resched()) {
4064 __local_bh_enable();
4072 EXPORT_SYMBOL(cond_resched_softirq
);
4076 * yield - yield the current processor to other threads.
4078 * this is a shortcut for kernel-space yielding - it marks the
4079 * thread runnable and calls sys_sched_yield().
4081 void __sched
yield(void)
4083 set_current_state(TASK_RUNNING
);
4087 EXPORT_SYMBOL(yield
);
4090 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4091 * that process accounting knows that this is a task in IO wait state.
4093 * But don't do that if it is a deliberate, throttling IO wait (this task
4094 * has set its backing_dev_info: the queue against which it should throttle)
4096 void __sched
io_schedule(void)
4098 struct runqueue
*rq
= &__raw_get_cpu_var(runqueues
);
4100 atomic_inc(&rq
->nr_iowait
);
4102 atomic_dec(&rq
->nr_iowait
);
4105 EXPORT_SYMBOL(io_schedule
);
4107 long __sched
io_schedule_timeout(long timeout
)
4109 struct runqueue
*rq
= &__raw_get_cpu_var(runqueues
);
4112 atomic_inc(&rq
->nr_iowait
);
4113 ret
= schedule_timeout(timeout
);
4114 atomic_dec(&rq
->nr_iowait
);
4119 * sys_sched_get_priority_max - return maximum RT priority.
4120 * @policy: scheduling class.
4122 * this syscall returns the maximum rt_priority that can be used
4123 * by a given scheduling class.
4125 asmlinkage
long sys_sched_get_priority_max(int policy
)
4132 ret
= MAX_USER_RT_PRIO
-1;
4143 * sys_sched_get_priority_min - return minimum RT priority.
4144 * @policy: scheduling class.
4146 * this syscall returns the minimum rt_priority that can be used
4147 * by a given scheduling class.
4149 asmlinkage
long sys_sched_get_priority_min(int policy
)
4166 * sys_sched_rr_get_interval - return the default timeslice of a process.
4167 * @pid: pid of the process.
4168 * @interval: userspace pointer to the timeslice value.
4170 * this syscall writes the default timeslice value of a given process
4171 * into the user-space timespec buffer. A value of '0' means infinity.
4174 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4176 int retval
= -EINVAL
;
4184 read_lock(&tasklist_lock
);
4185 p
= find_process_by_pid(pid
);
4189 retval
= security_task_getscheduler(p
);
4193 jiffies_to_timespec(p
->policy
== SCHED_FIFO
?
4194 0 : task_timeslice(p
), &t
);
4195 read_unlock(&tasklist_lock
);
4196 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4200 read_unlock(&tasklist_lock
);
4204 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4206 if (list_empty(&p
->children
)) return NULL
;
4207 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4210 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4212 if (p
->sibling
.prev
==&p
->parent
->children
) return NULL
;
4213 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4216 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4218 if (p
->sibling
.next
==&p
->parent
->children
) return NULL
;
4219 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4222 static void show_task(task_t
*p
)
4226 unsigned long free
= 0;
4227 static const char *stat_nam
[] = { "R", "S", "D", "T", "t", "Z", "X" };
4229 printk("%-13.13s ", p
->comm
);
4230 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4231 if (state
< ARRAY_SIZE(stat_nam
))
4232 printk(stat_nam
[state
]);
4235 #if (BITS_PER_LONG == 32)
4236 if (state
== TASK_RUNNING
)
4237 printk(" running ");
4239 printk(" %08lX ", thread_saved_pc(p
));
4241 if (state
== TASK_RUNNING
)
4242 printk(" running task ");
4244 printk(" %016lx ", thread_saved_pc(p
));
4246 #ifdef CONFIG_DEBUG_STACK_USAGE
4248 unsigned long *n
= end_of_stack(p
);
4251 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4254 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4255 if ((relative
= eldest_child(p
)))
4256 printk("%5d ", relative
->pid
);
4259 if ((relative
= younger_sibling(p
)))
4260 printk("%7d", relative
->pid
);
4263 if ((relative
= older_sibling(p
)))
4264 printk(" %5d", relative
->pid
);
4268 printk(" (L-TLB)\n");
4270 printk(" (NOTLB)\n");
4272 if (state
!= TASK_RUNNING
)
4273 show_stack(p
, NULL
);
4276 void show_state(void)
4280 #if (BITS_PER_LONG == 32)
4283 printk(" task PC pid father child younger older\n");
4287 printk(" task PC pid father child younger older\n");
4289 read_lock(&tasklist_lock
);
4290 do_each_thread(g
, p
) {
4292 * reset the NMI-timeout, listing all files on a slow
4293 * console might take alot of time:
4295 touch_nmi_watchdog();
4297 } while_each_thread(g
, p
);
4299 read_unlock(&tasklist_lock
);
4300 mutex_debug_show_all_locks();
4304 * init_idle - set up an idle thread for a given CPU
4305 * @idle: task in question
4306 * @cpu: cpu the idle task belongs to
4308 * NOTE: this function does not set the idle thread's NEED_RESCHED
4309 * flag, to make booting more robust.
4311 void __devinit
init_idle(task_t
*idle
, int cpu
)
4313 runqueue_t
*rq
= cpu_rq(cpu
);
4314 unsigned long flags
;
4316 idle
->timestamp
= sched_clock();
4317 idle
->sleep_avg
= 0;
4319 idle
->prio
= MAX_PRIO
;
4320 idle
->state
= TASK_RUNNING
;
4321 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4322 set_task_cpu(idle
, cpu
);
4324 spin_lock_irqsave(&rq
->lock
, flags
);
4325 rq
->curr
= rq
->idle
= idle
;
4326 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4329 spin_unlock_irqrestore(&rq
->lock
, flags
);
4331 /* Set the preempt count _outside_ the spinlocks! */
4332 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4333 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4335 task_thread_info(idle
)->preempt_count
= 0;
4340 * In a system that switches off the HZ timer nohz_cpu_mask
4341 * indicates which cpus entered this state. This is used
4342 * in the rcu update to wait only for active cpus. For system
4343 * which do not switch off the HZ timer nohz_cpu_mask should
4344 * always be CPU_MASK_NONE.
4346 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4350 * This is how migration works:
4352 * 1) we queue a migration_req_t structure in the source CPU's
4353 * runqueue and wake up that CPU's migration thread.
4354 * 2) we down() the locked semaphore => thread blocks.
4355 * 3) migration thread wakes up (implicitly it forces the migrated
4356 * thread off the CPU)
4357 * 4) it gets the migration request and checks whether the migrated
4358 * task is still in the wrong runqueue.
4359 * 5) if it's in the wrong runqueue then the migration thread removes
4360 * it and puts it into the right queue.
4361 * 6) migration thread up()s the semaphore.
4362 * 7) we wake up and the migration is done.
4366 * Change a given task's CPU affinity. Migrate the thread to a
4367 * proper CPU and schedule it away if the CPU it's executing on
4368 * is removed from the allowed bitmask.
4370 * NOTE: the caller must have a valid reference to the task, the
4371 * task must not exit() & deallocate itself prematurely. The
4372 * call is not atomic; no spinlocks may be held.
4374 int set_cpus_allowed(task_t
*p
, cpumask_t new_mask
)
4376 unsigned long flags
;
4378 migration_req_t req
;
4381 rq
= task_rq_lock(p
, &flags
);
4382 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
4387 p
->cpus_allowed
= new_mask
;
4388 /* Can the task run on the task's current CPU? If so, we're done */
4389 if (cpu_isset(task_cpu(p
), new_mask
))
4392 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
4393 /* Need help from migration thread: drop lock and wait. */
4394 task_rq_unlock(rq
, &flags
);
4395 wake_up_process(rq
->migration_thread
);
4396 wait_for_completion(&req
.done
);
4397 tlb_migrate_finish(p
->mm
);
4401 task_rq_unlock(rq
, &flags
);
4405 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
4408 * Move (not current) task off this cpu, onto dest cpu. We're doing
4409 * this because either it can't run here any more (set_cpus_allowed()
4410 * away from this CPU, or CPU going down), or because we're
4411 * attempting to rebalance this task on exec (sched_exec).
4413 * So we race with normal scheduler movements, but that's OK, as long
4414 * as the task is no longer on this CPU.
4416 static void __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
4418 runqueue_t
*rq_dest
, *rq_src
;
4420 if (unlikely(cpu_is_offline(dest_cpu
)))
4423 rq_src
= cpu_rq(src_cpu
);
4424 rq_dest
= cpu_rq(dest_cpu
);
4426 double_rq_lock(rq_src
, rq_dest
);
4427 /* Already moved. */
4428 if (task_cpu(p
) != src_cpu
)
4430 /* Affinity changed (again). */
4431 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
4434 set_task_cpu(p
, dest_cpu
);
4437 * Sync timestamp with rq_dest's before activating.
4438 * The same thing could be achieved by doing this step
4439 * afterwards, and pretending it was a local activate.
4440 * This way is cleaner and logically correct.
4442 p
->timestamp
= p
->timestamp
- rq_src
->timestamp_last_tick
4443 + rq_dest
->timestamp_last_tick
;
4444 deactivate_task(p
, rq_src
);
4445 activate_task(p
, rq_dest
, 0);
4446 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
4447 resched_task(rq_dest
->curr
);
4451 double_rq_unlock(rq_src
, rq_dest
);
4455 * migration_thread - this is a highprio system thread that performs
4456 * thread migration by bumping thread off CPU then 'pushing' onto
4459 static int migration_thread(void *data
)
4462 int cpu
= (long)data
;
4465 BUG_ON(rq
->migration_thread
!= current
);
4467 set_current_state(TASK_INTERRUPTIBLE
);
4468 while (!kthread_should_stop()) {
4469 struct list_head
*head
;
4470 migration_req_t
*req
;
4474 spin_lock_irq(&rq
->lock
);
4476 if (cpu_is_offline(cpu
)) {
4477 spin_unlock_irq(&rq
->lock
);
4481 if (rq
->active_balance
) {
4482 active_load_balance(rq
, cpu
);
4483 rq
->active_balance
= 0;
4486 head
= &rq
->migration_queue
;
4488 if (list_empty(head
)) {
4489 spin_unlock_irq(&rq
->lock
);
4491 set_current_state(TASK_INTERRUPTIBLE
);
4494 req
= list_entry(head
->next
, migration_req_t
, list
);
4495 list_del_init(head
->next
);
4497 spin_unlock(&rq
->lock
);
4498 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
4501 complete(&req
->done
);
4503 __set_current_state(TASK_RUNNING
);
4507 /* Wait for kthread_stop */
4508 set_current_state(TASK_INTERRUPTIBLE
);
4509 while (!kthread_should_stop()) {
4511 set_current_state(TASK_INTERRUPTIBLE
);
4513 __set_current_state(TASK_RUNNING
);
4517 #ifdef CONFIG_HOTPLUG_CPU
4518 /* Figure out where task on dead CPU should go, use force if neccessary. */
4519 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*tsk
)
4525 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
4526 cpus_and(mask
, mask
, tsk
->cpus_allowed
);
4527 dest_cpu
= any_online_cpu(mask
);
4529 /* On any allowed CPU? */
4530 if (dest_cpu
== NR_CPUS
)
4531 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4533 /* No more Mr. Nice Guy. */
4534 if (dest_cpu
== NR_CPUS
) {
4535 cpus_setall(tsk
->cpus_allowed
);
4536 dest_cpu
= any_online_cpu(tsk
->cpus_allowed
);
4539 * Don't tell them about moving exiting tasks or
4540 * kernel threads (both mm NULL), since they never
4543 if (tsk
->mm
&& printk_ratelimit())
4544 printk(KERN_INFO
"process %d (%s) no "
4545 "longer affine to cpu%d\n",
4546 tsk
->pid
, tsk
->comm
, dead_cpu
);
4548 __migrate_task(tsk
, dead_cpu
, dest_cpu
);
4552 * While a dead CPU has no uninterruptible tasks queued at this point,
4553 * it might still have a nonzero ->nr_uninterruptible counter, because
4554 * for performance reasons the counter is not stricly tracking tasks to
4555 * their home CPUs. So we just add the counter to another CPU's counter,
4556 * to keep the global sum constant after CPU-down:
4558 static void migrate_nr_uninterruptible(runqueue_t
*rq_src
)
4560 runqueue_t
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
4561 unsigned long flags
;
4563 local_irq_save(flags
);
4564 double_rq_lock(rq_src
, rq_dest
);
4565 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
4566 rq_src
->nr_uninterruptible
= 0;
4567 double_rq_unlock(rq_src
, rq_dest
);
4568 local_irq_restore(flags
);
4571 /* Run through task list and migrate tasks from the dead cpu. */
4572 static void migrate_live_tasks(int src_cpu
)
4574 struct task_struct
*tsk
, *t
;
4576 write_lock_irq(&tasklist_lock
);
4578 do_each_thread(t
, tsk
) {
4582 if (task_cpu(tsk
) == src_cpu
)
4583 move_task_off_dead_cpu(src_cpu
, tsk
);
4584 } while_each_thread(t
, tsk
);
4586 write_unlock_irq(&tasklist_lock
);
4589 /* Schedules idle task to be the next runnable task on current CPU.
4590 * It does so by boosting its priority to highest possible and adding it to
4591 * the _front_ of runqueue. Used by CPU offline code.
4593 void sched_idle_next(void)
4595 int cpu
= smp_processor_id();
4596 runqueue_t
*rq
= this_rq();
4597 struct task_struct
*p
= rq
->idle
;
4598 unsigned long flags
;
4600 /* cpu has to be offline */
4601 BUG_ON(cpu_online(cpu
));
4603 /* Strictly not necessary since rest of the CPUs are stopped by now
4604 * and interrupts disabled on current cpu.
4606 spin_lock_irqsave(&rq
->lock
, flags
);
4608 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4609 /* Add idle task to _front_ of it's priority queue */
4610 __activate_idle_task(p
, rq
);
4612 spin_unlock_irqrestore(&rq
->lock
, flags
);
4615 /* Ensures that the idle task is using init_mm right before its cpu goes
4618 void idle_task_exit(void)
4620 struct mm_struct
*mm
= current
->active_mm
;
4622 BUG_ON(cpu_online(smp_processor_id()));
4625 switch_mm(mm
, &init_mm
, current
);
4629 static void migrate_dead(unsigned int dead_cpu
, task_t
*tsk
)
4631 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4633 /* Must be exiting, otherwise would be on tasklist. */
4634 BUG_ON(tsk
->exit_state
!= EXIT_ZOMBIE
&& tsk
->exit_state
!= EXIT_DEAD
);
4636 /* Cannot have done final schedule yet: would have vanished. */
4637 BUG_ON(tsk
->flags
& PF_DEAD
);
4639 get_task_struct(tsk
);
4642 * Drop lock around migration; if someone else moves it,
4643 * that's OK. No task can be added to this CPU, so iteration is
4646 spin_unlock_irq(&rq
->lock
);
4647 move_task_off_dead_cpu(dead_cpu
, tsk
);
4648 spin_lock_irq(&rq
->lock
);
4650 put_task_struct(tsk
);
4653 /* release_task() removes task from tasklist, so we won't find dead tasks. */
4654 static void migrate_dead_tasks(unsigned int dead_cpu
)
4657 struct runqueue
*rq
= cpu_rq(dead_cpu
);
4659 for (arr
= 0; arr
< 2; arr
++) {
4660 for (i
= 0; i
< MAX_PRIO
; i
++) {
4661 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
4662 while (!list_empty(list
))
4663 migrate_dead(dead_cpu
,
4664 list_entry(list
->next
, task_t
,
4669 #endif /* CONFIG_HOTPLUG_CPU */
4672 * migration_call - callback that gets triggered when a CPU is added.
4673 * Here we can start up the necessary migration thread for the new CPU.
4675 static int __cpuinit
migration_call(struct notifier_block
*nfb
,
4676 unsigned long action
,
4679 int cpu
= (long)hcpu
;
4680 struct task_struct
*p
;
4681 struct runqueue
*rq
;
4682 unsigned long flags
;
4685 case CPU_UP_PREPARE
:
4686 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
4689 p
->flags
|= PF_NOFREEZE
;
4690 kthread_bind(p
, cpu
);
4691 /* Must be high prio: stop_machine expects to yield to it. */
4692 rq
= task_rq_lock(p
, &flags
);
4693 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
4694 task_rq_unlock(rq
, &flags
);
4695 cpu_rq(cpu
)->migration_thread
= p
;
4698 /* Strictly unneccessary, as first user will wake it. */
4699 wake_up_process(cpu_rq(cpu
)->migration_thread
);
4701 #ifdef CONFIG_HOTPLUG_CPU
4702 case CPU_UP_CANCELED
:
4703 if (!cpu_rq(cpu
)->migration_thread
)
4705 /* Unbind it from offline cpu so it can run. Fall thru. */
4706 kthread_bind(cpu_rq(cpu
)->migration_thread
,
4707 any_online_cpu(cpu_online_map
));
4708 kthread_stop(cpu_rq(cpu
)->migration_thread
);
4709 cpu_rq(cpu
)->migration_thread
= NULL
;
4712 migrate_live_tasks(cpu
);
4714 kthread_stop(rq
->migration_thread
);
4715 rq
->migration_thread
= NULL
;
4716 /* Idle task back to normal (off runqueue, low prio) */
4717 rq
= task_rq_lock(rq
->idle
, &flags
);
4718 deactivate_task(rq
->idle
, rq
);
4719 rq
->idle
->static_prio
= MAX_PRIO
;
4720 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
4721 migrate_dead_tasks(cpu
);
4722 task_rq_unlock(rq
, &flags
);
4723 migrate_nr_uninterruptible(rq
);
4724 BUG_ON(rq
->nr_running
!= 0);
4726 /* No need to migrate the tasks: it was best-effort if
4727 * they didn't do lock_cpu_hotplug(). Just wake up
4728 * the requestors. */
4729 spin_lock_irq(&rq
->lock
);
4730 while (!list_empty(&rq
->migration_queue
)) {
4731 migration_req_t
*req
;
4732 req
= list_entry(rq
->migration_queue
.next
,
4733 migration_req_t
, list
);
4734 list_del_init(&req
->list
);
4735 complete(&req
->done
);
4737 spin_unlock_irq(&rq
->lock
);
4744 /* Register at highest priority so that task migration (migrate_all_tasks)
4745 * happens before everything else.
4747 static struct notifier_block __cpuinitdata migration_notifier
= {
4748 .notifier_call
= migration_call
,
4752 int __init
migration_init(void)
4754 void *cpu
= (void *)(long)smp_processor_id();
4755 /* Start one for boot CPU. */
4756 migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
4757 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
4758 register_cpu_notifier(&migration_notifier
);
4764 #undef SCHED_DOMAIN_DEBUG
4765 #ifdef SCHED_DOMAIN_DEBUG
4766 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
4771 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
4775 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
4780 struct sched_group
*group
= sd
->groups
;
4781 cpumask_t groupmask
;
4783 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
4784 cpus_clear(groupmask
);
4787 for (i
= 0; i
< level
+ 1; i
++)
4789 printk("domain %d: ", level
);
4791 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
4792 printk("does not load-balance\n");
4794 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain has parent");
4798 printk("span %s\n", str
);
4800 if (!cpu_isset(cpu
, sd
->span
))
4801 printk(KERN_ERR
"ERROR: domain->span does not contain CPU%d\n", cpu
);
4802 if (!cpu_isset(cpu
, group
->cpumask
))
4803 printk(KERN_ERR
"ERROR: domain->groups does not contain CPU%d\n", cpu
);
4806 for (i
= 0; i
< level
+ 2; i
++)
4812 printk(KERN_ERR
"ERROR: group is NULL\n");
4816 if (!group
->cpu_power
) {
4818 printk(KERN_ERR
"ERROR: domain->cpu_power not set\n");
4821 if (!cpus_weight(group
->cpumask
)) {
4823 printk(KERN_ERR
"ERROR: empty group\n");
4826 if (cpus_intersects(groupmask
, group
->cpumask
)) {
4828 printk(KERN_ERR
"ERROR: repeated CPUs\n");
4831 cpus_or(groupmask
, groupmask
, group
->cpumask
);
4833 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
4836 group
= group
->next
;
4837 } while (group
!= sd
->groups
);
4840 if (!cpus_equal(sd
->span
, groupmask
))
4841 printk(KERN_ERR
"ERROR: groups don't span domain->span\n");
4847 if (!cpus_subset(groupmask
, sd
->span
))
4848 printk(KERN_ERR
"ERROR: parent span is not a superset of domain->span\n");
4854 #define sched_domain_debug(sd, cpu) {}
4857 static int sd_degenerate(struct sched_domain
*sd
)
4859 if (cpus_weight(sd
->span
) == 1)
4862 /* Following flags need at least 2 groups */
4863 if (sd
->flags
& (SD_LOAD_BALANCE
|
4864 SD_BALANCE_NEWIDLE
|
4867 if (sd
->groups
!= sd
->groups
->next
)
4871 /* Following flags don't use groups */
4872 if (sd
->flags
& (SD_WAKE_IDLE
|
4880 static int sd_parent_degenerate(struct sched_domain
*sd
,
4881 struct sched_domain
*parent
)
4883 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
4885 if (sd_degenerate(parent
))
4888 if (!cpus_equal(sd
->span
, parent
->span
))
4891 /* Does parent contain flags not in child? */
4892 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
4893 if (cflags
& SD_WAKE_AFFINE
)
4894 pflags
&= ~SD_WAKE_BALANCE
;
4895 /* Flags needing groups don't count if only 1 group in parent */
4896 if (parent
->groups
== parent
->groups
->next
) {
4897 pflags
&= ~(SD_LOAD_BALANCE
|
4898 SD_BALANCE_NEWIDLE
|
4902 if (~cflags
& pflags
)
4909 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
4910 * hold the hotplug lock.
4912 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
4914 runqueue_t
*rq
= cpu_rq(cpu
);
4915 struct sched_domain
*tmp
;
4917 /* Remove the sched domains which do not contribute to scheduling. */
4918 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
4919 struct sched_domain
*parent
= tmp
->parent
;
4922 if (sd_parent_degenerate(tmp
, parent
))
4923 tmp
->parent
= parent
->parent
;
4926 if (sd
&& sd_degenerate(sd
))
4929 sched_domain_debug(sd
, cpu
);
4931 rcu_assign_pointer(rq
->sd
, sd
);
4934 /* cpus with isolated domains */
4935 static cpumask_t __devinitdata cpu_isolated_map
= CPU_MASK_NONE
;
4937 /* Setup the mask of cpus configured for isolated domains */
4938 static int __init
isolated_cpu_setup(char *str
)
4940 int ints
[NR_CPUS
], i
;
4942 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
4943 cpus_clear(cpu_isolated_map
);
4944 for (i
= 1; i
<= ints
[0]; i
++)
4945 if (ints
[i
] < NR_CPUS
)
4946 cpu_set(ints
[i
], cpu_isolated_map
);
4950 __setup ("isolcpus=", isolated_cpu_setup
);
4953 * init_sched_build_groups takes an array of groups, the cpumask we wish
4954 * to span, and a pointer to a function which identifies what group a CPU
4955 * belongs to. The return value of group_fn must be a valid index into the
4956 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
4957 * keep track of groups covered with a cpumask_t).
4959 * init_sched_build_groups will build a circular linked list of the groups
4960 * covered by the given span, and will set each group's ->cpumask correctly,
4961 * and ->cpu_power to 0.
4963 static void init_sched_build_groups(struct sched_group groups
[], cpumask_t span
,
4964 int (*group_fn
)(int cpu
))
4966 struct sched_group
*first
= NULL
, *last
= NULL
;
4967 cpumask_t covered
= CPU_MASK_NONE
;
4970 for_each_cpu_mask(i
, span
) {
4971 int group
= group_fn(i
);
4972 struct sched_group
*sg
= &groups
[group
];
4975 if (cpu_isset(i
, covered
))
4978 sg
->cpumask
= CPU_MASK_NONE
;
4981 for_each_cpu_mask(j
, span
) {
4982 if (group_fn(j
) != group
)
4985 cpu_set(j
, covered
);
4986 cpu_set(j
, sg
->cpumask
);
4997 #define SD_NODES_PER_DOMAIN 16
5000 * Self-tuning task migration cost measurement between source and target CPUs.
5002 * This is done by measuring the cost of manipulating buffers of varying
5003 * sizes. For a given buffer-size here are the steps that are taken:
5005 * 1) the source CPU reads+dirties a shared buffer
5006 * 2) the target CPU reads+dirties the same shared buffer
5008 * We measure how long they take, in the following 4 scenarios:
5010 * - source: CPU1, target: CPU2 | cost1
5011 * - source: CPU2, target: CPU1 | cost2
5012 * - source: CPU1, target: CPU1 | cost3
5013 * - source: CPU2, target: CPU2 | cost4
5015 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5016 * the cost of migration.
5018 * We then start off from a small buffer-size and iterate up to larger
5019 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5020 * doing a maximum search for the cost. (The maximum cost for a migration
5021 * normally occurs when the working set size is around the effective cache
5024 #define SEARCH_SCOPE 2
5025 #define MIN_CACHE_SIZE (64*1024U)
5026 #define DEFAULT_CACHE_SIZE (5*1024*1024U)
5027 #define ITERATIONS 1
5028 #define SIZE_THRESH 130
5029 #define COST_THRESH 130
5032 * The migration cost is a function of 'domain distance'. Domain
5033 * distance is the number of steps a CPU has to iterate down its
5034 * domain tree to share a domain with the other CPU. The farther
5035 * two CPUs are from each other, the larger the distance gets.
5037 * Note that we use the distance only to cache measurement results,
5038 * the distance value is not used numerically otherwise. When two
5039 * CPUs have the same distance it is assumed that the migration
5040 * cost is the same. (this is a simplification but quite practical)
5042 #define MAX_DOMAIN_DISTANCE 32
5044 static unsigned long long migration_cost
[MAX_DOMAIN_DISTANCE
] =
5045 { [ 0 ... MAX_DOMAIN_DISTANCE
-1 ] =
5047 * Architectures may override the migration cost and thus avoid
5048 * boot-time calibration. Unit is nanoseconds. Mostly useful for
5049 * virtualized hardware:
5051 #ifdef CONFIG_DEFAULT_MIGRATION_COST
5052 CONFIG_DEFAULT_MIGRATION_COST
5059 * Allow override of migration cost - in units of microseconds.
5060 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5061 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5063 static int __init
migration_cost_setup(char *str
)
5065 int ints
[MAX_DOMAIN_DISTANCE
+1], i
;
5067 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5069 printk("#ints: %d\n", ints
[0]);
5070 for (i
= 1; i
<= ints
[0]; i
++) {
5071 migration_cost
[i
-1] = (unsigned long long)ints
[i
]*1000;
5072 printk("migration_cost[%d]: %Ld\n", i
-1, migration_cost
[i
-1]);
5077 __setup ("migration_cost=", migration_cost_setup
);
5080 * Global multiplier (divisor) for migration-cutoff values,
5081 * in percentiles. E.g. use a value of 150 to get 1.5 times
5082 * longer cache-hot cutoff times.
5084 * (We scale it from 100 to 128 to long long handling easier.)
5087 #define MIGRATION_FACTOR_SCALE 128
5089 static unsigned int migration_factor
= MIGRATION_FACTOR_SCALE
;
5091 static int __init
setup_migration_factor(char *str
)
5093 get_option(&str
, &migration_factor
);
5094 migration_factor
= migration_factor
* MIGRATION_FACTOR_SCALE
/ 100;
5098 __setup("migration_factor=", setup_migration_factor
);
5101 * Estimated distance of two CPUs, measured via the number of domains
5102 * we have to pass for the two CPUs to be in the same span:
5104 static unsigned long domain_distance(int cpu1
, int cpu2
)
5106 unsigned long distance
= 0;
5107 struct sched_domain
*sd
;
5109 for_each_domain(cpu1
, sd
) {
5110 WARN_ON(!cpu_isset(cpu1
, sd
->span
));
5111 if (cpu_isset(cpu2
, sd
->span
))
5115 if (distance
>= MAX_DOMAIN_DISTANCE
) {
5117 distance
= MAX_DOMAIN_DISTANCE
-1;
5123 static unsigned int migration_debug
;
5125 static int __init
setup_migration_debug(char *str
)
5127 get_option(&str
, &migration_debug
);
5131 __setup("migration_debug=", setup_migration_debug
);
5134 * Maximum cache-size that the scheduler should try to measure.
5135 * Architectures with larger caches should tune this up during
5136 * bootup. Gets used in the domain-setup code (i.e. during SMP
5139 unsigned int max_cache_size
;
5141 static int __init
setup_max_cache_size(char *str
)
5143 get_option(&str
, &max_cache_size
);
5147 __setup("max_cache_size=", setup_max_cache_size
);
5150 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5151 * is the operation that is timed, so we try to generate unpredictable
5152 * cachemisses that still end up filling the L2 cache:
5154 static void touch_cache(void *__cache
, unsigned long __size
)
5156 unsigned long size
= __size
/sizeof(long), chunk1
= size
/3,
5158 unsigned long *cache
= __cache
;
5161 for (i
= 0; i
< size
/6; i
+= 8) {
5164 case 1: cache
[size
-1-i
]++;
5165 case 2: cache
[chunk1
-i
]++;
5166 case 3: cache
[chunk1
+i
]++;
5167 case 4: cache
[chunk2
-i
]++;
5168 case 5: cache
[chunk2
+i
]++;
5174 * Measure the cache-cost of one task migration. Returns in units of nsec.
5176 static unsigned long long measure_one(void *cache
, unsigned long size
,
5177 int source
, int target
)
5179 cpumask_t mask
, saved_mask
;
5180 unsigned long long t0
, t1
, t2
, t3
, cost
;
5182 saved_mask
= current
->cpus_allowed
;
5185 * Flush source caches to RAM and invalidate them:
5190 * Migrate to the source CPU:
5192 mask
= cpumask_of_cpu(source
);
5193 set_cpus_allowed(current
, mask
);
5194 WARN_ON(smp_processor_id() != source
);
5197 * Dirty the working set:
5200 touch_cache(cache
, size
);
5204 * Migrate to the target CPU, dirty the L2 cache and access
5205 * the shared buffer. (which represents the working set
5206 * of a migrated task.)
5208 mask
= cpumask_of_cpu(target
);
5209 set_cpus_allowed(current
, mask
);
5210 WARN_ON(smp_processor_id() != target
);
5213 touch_cache(cache
, size
);
5216 cost
= t1
-t0
+ t3
-t2
;
5218 if (migration_debug
>= 2)
5219 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5220 source
, target
, t1
-t0
, t1
-t0
, t3
-t2
, cost
);
5222 * Flush target caches to RAM and invalidate them:
5226 set_cpus_allowed(current
, saved_mask
);
5232 * Measure a series of task migrations and return the average
5233 * result. Since this code runs early during bootup the system
5234 * is 'undisturbed' and the average latency makes sense.
5236 * The algorithm in essence auto-detects the relevant cache-size,
5237 * so it will properly detect different cachesizes for different
5238 * cache-hierarchies, depending on how the CPUs are connected.
5240 * Architectures can prime the upper limit of the search range via
5241 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5243 static unsigned long long
5244 measure_cost(int cpu1
, int cpu2
, void *cache
, unsigned int size
)
5246 unsigned long long cost1
, cost2
;
5250 * Measure the migration cost of 'size' bytes, over an
5251 * average of 10 runs:
5253 * (We perturb the cache size by a small (0..4k)
5254 * value to compensate size/alignment related artifacts.
5255 * We also subtract the cost of the operation done on
5261 * dry run, to make sure we start off cache-cold on cpu1,
5262 * and to get any vmalloc pagefaults in advance:
5264 measure_one(cache
, size
, cpu1
, cpu2
);
5265 for (i
= 0; i
< ITERATIONS
; i
++)
5266 cost1
+= measure_one(cache
, size
- i
*1024, cpu1
, cpu2
);
5268 measure_one(cache
, size
, cpu2
, cpu1
);
5269 for (i
= 0; i
< ITERATIONS
; i
++)
5270 cost1
+= measure_one(cache
, size
- i
*1024, cpu2
, cpu1
);
5273 * (We measure the non-migrating [cached] cost on both
5274 * cpu1 and cpu2, to handle CPUs with different speeds)
5278 measure_one(cache
, size
, cpu1
, cpu1
);
5279 for (i
= 0; i
< ITERATIONS
; i
++)
5280 cost2
+= measure_one(cache
, size
- i
*1024, cpu1
, cpu1
);
5282 measure_one(cache
, size
, cpu2
, cpu2
);
5283 for (i
= 0; i
< ITERATIONS
; i
++)
5284 cost2
+= measure_one(cache
, size
- i
*1024, cpu2
, cpu2
);
5287 * Get the per-iteration migration cost:
5289 do_div(cost1
, 2*ITERATIONS
);
5290 do_div(cost2
, 2*ITERATIONS
);
5292 return cost1
- cost2
;
5295 static unsigned long long measure_migration_cost(int cpu1
, int cpu2
)
5297 unsigned long long max_cost
= 0, fluct
= 0, avg_fluct
= 0;
5298 unsigned int max_size
, size
, size_found
= 0;
5299 long long cost
= 0, prev_cost
;
5303 * Search from max_cache_size*5 down to 64K - the real relevant
5304 * cachesize has to lie somewhere inbetween.
5306 if (max_cache_size
) {
5307 max_size
= max(max_cache_size
* SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5308 size
= max(max_cache_size
/ SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5311 * Since we have no estimation about the relevant
5314 max_size
= DEFAULT_CACHE_SIZE
* SEARCH_SCOPE
;
5315 size
= MIN_CACHE_SIZE
;
5318 if (!cpu_online(cpu1
) || !cpu_online(cpu2
)) {
5319 printk("cpu %d and %d not both online!\n", cpu1
, cpu2
);
5324 * Allocate the working set:
5326 cache
= vmalloc(max_size
);
5328 printk("could not vmalloc %d bytes for cache!\n", 2*max_size
);
5329 return 1000000; // return 1 msec on very small boxen
5332 while (size
<= max_size
) {
5334 cost
= measure_cost(cpu1
, cpu2
, cache
, size
);
5340 if (max_cost
< cost
) {
5346 * Calculate average fluctuation, we use this to prevent
5347 * noise from triggering an early break out of the loop:
5349 fluct
= abs(cost
- prev_cost
);
5350 avg_fluct
= (avg_fluct
+ fluct
)/2;
5352 if (migration_debug
)
5353 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): (%8Ld %8Ld)\n",
5355 (long)cost
/ 1000000,
5356 ((long)cost
/ 100000) % 10,
5357 (long)max_cost
/ 1000000,
5358 ((long)max_cost
/ 100000) % 10,
5359 domain_distance(cpu1
, cpu2
),
5363 * If we iterated at least 20% past the previous maximum,
5364 * and the cost has dropped by more than 20% already,
5365 * (taking fluctuations into account) then we assume to
5366 * have found the maximum and break out of the loop early:
5368 if (size_found
&& (size
*100 > size_found
*SIZE_THRESH
))
5369 if (cost
+avg_fluct
<= 0 ||
5370 max_cost
*100 > (cost
+avg_fluct
)*COST_THRESH
) {
5372 if (migration_debug
)
5373 printk("-> found max.\n");
5377 * Increase the cachesize in 10% steps:
5379 size
= size
* 10 / 9;
5382 if (migration_debug
)
5383 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
5384 cpu1
, cpu2
, size_found
, max_cost
);
5389 * A task is considered 'cache cold' if at least 2 times
5390 * the worst-case cost of migration has passed.
5392 * (this limit is only listened to if the load-balancing
5393 * situation is 'nice' - if there is a large imbalance we
5394 * ignore it for the sake of CPU utilization and
5395 * processing fairness.)
5397 return 2 * max_cost
* migration_factor
/ MIGRATION_FACTOR_SCALE
;
5400 static void calibrate_migration_costs(const cpumask_t
*cpu_map
)
5402 int cpu1
= -1, cpu2
= -1, cpu
, orig_cpu
= raw_smp_processor_id();
5403 unsigned long j0
, j1
, distance
, max_distance
= 0;
5404 struct sched_domain
*sd
;
5409 * First pass - calculate the cacheflush times:
5411 for_each_cpu_mask(cpu1
, *cpu_map
) {
5412 for_each_cpu_mask(cpu2
, *cpu_map
) {
5415 distance
= domain_distance(cpu1
, cpu2
);
5416 max_distance
= max(max_distance
, distance
);
5418 * No result cached yet?
5420 if (migration_cost
[distance
] == -1LL)
5421 migration_cost
[distance
] =
5422 measure_migration_cost(cpu1
, cpu2
);
5426 * Second pass - update the sched domain hierarchy with
5427 * the new cache-hot-time estimations:
5429 for_each_cpu_mask(cpu
, *cpu_map
) {
5431 for_each_domain(cpu
, sd
) {
5432 sd
->cache_hot_time
= migration_cost
[distance
];
5439 if (migration_debug
)
5440 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
5448 if (system_state
== SYSTEM_BOOTING
) {
5449 printk("migration_cost=");
5450 for (distance
= 0; distance
<= max_distance
; distance
++) {
5453 printk("%ld", (long)migration_cost
[distance
] / 1000);
5458 if (migration_debug
)
5459 printk("migration: %ld seconds\n", (j1
-j0
)/HZ
);
5462 * Move back to the original CPU. NUMA-Q gets confused
5463 * if we migrate to another quad during bootup.
5465 if (raw_smp_processor_id() != orig_cpu
) {
5466 cpumask_t mask
= cpumask_of_cpu(orig_cpu
),
5467 saved_mask
= current
->cpus_allowed
;
5469 set_cpus_allowed(current
, mask
);
5470 set_cpus_allowed(current
, saved_mask
);
5477 * find_next_best_node - find the next node to include in a sched_domain
5478 * @node: node whose sched_domain we're building
5479 * @used_nodes: nodes already in the sched_domain
5481 * Find the next node to include in a given scheduling domain. Simply
5482 * finds the closest node not already in the @used_nodes map.
5484 * Should use nodemask_t.
5486 static int find_next_best_node(int node
, unsigned long *used_nodes
)
5488 int i
, n
, val
, min_val
, best_node
= 0;
5492 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5493 /* Start at @node */
5494 n
= (node
+ i
) % MAX_NUMNODES
;
5496 if (!nr_cpus_node(n
))
5499 /* Skip already used nodes */
5500 if (test_bit(n
, used_nodes
))
5503 /* Simple min distance search */
5504 val
= node_distance(node
, n
);
5506 if (val
< min_val
) {
5512 set_bit(best_node
, used_nodes
);
5517 * sched_domain_node_span - get a cpumask for a node's sched_domain
5518 * @node: node whose cpumask we're constructing
5519 * @size: number of nodes to include in this span
5521 * Given a node, construct a good cpumask for its sched_domain to span. It
5522 * should be one that prevents unnecessary balancing, but also spreads tasks
5525 static cpumask_t
sched_domain_node_span(int node
)
5528 cpumask_t span
, nodemask
;
5529 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
5532 bitmap_zero(used_nodes
, MAX_NUMNODES
);
5534 nodemask
= node_to_cpumask(node
);
5535 cpus_or(span
, span
, nodemask
);
5536 set_bit(node
, used_nodes
);
5538 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
5539 int next_node
= find_next_best_node(node
, used_nodes
);
5540 nodemask
= node_to_cpumask(next_node
);
5541 cpus_or(span
, span
, nodemask
);
5549 * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
5550 * can switch it on easily if needed.
5552 #ifdef CONFIG_SCHED_SMT
5553 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
5554 static struct sched_group sched_group_cpus
[NR_CPUS
];
5555 static int cpu_to_cpu_group(int cpu
)
5561 #ifdef CONFIG_SCHED_MC
5562 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
5563 static struct sched_group sched_group_core
[NR_CPUS
];
5566 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
5567 static int cpu_to_core_group(int cpu
)
5569 return first_cpu(cpu_sibling_map
[cpu
]);
5571 #elif defined(CONFIG_SCHED_MC)
5572 static int cpu_to_core_group(int cpu
)
5578 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
5579 static struct sched_group sched_group_phys
[NR_CPUS
];
5580 static int cpu_to_phys_group(int cpu
)
5582 #if defined(CONFIG_SCHED_MC)
5583 cpumask_t mask
= cpu_coregroup_map(cpu
);
5584 return first_cpu(mask
);
5585 #elif defined(CONFIG_SCHED_SMT)
5586 return first_cpu(cpu_sibling_map
[cpu
]);
5594 * The init_sched_build_groups can't handle what we want to do with node
5595 * groups, so roll our own. Now each node has its own list of groups which
5596 * gets dynamically allocated.
5598 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
5599 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
5601 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
5602 static struct sched_group
*sched_group_allnodes_bycpu
[NR_CPUS
];
5604 static int cpu_to_allnodes_group(int cpu
)
5606 return cpu_to_node(cpu
);
5608 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
5610 struct sched_group
*sg
= group_head
;
5616 for_each_cpu_mask(j
, sg
->cpumask
) {
5617 struct sched_domain
*sd
;
5619 sd
= &per_cpu(phys_domains
, j
);
5620 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
5622 * Only add "power" once for each
5628 sg
->cpu_power
+= sd
->groups
->cpu_power
;
5631 if (sg
!= group_head
)
5637 * Build sched domains for a given set of cpus and attach the sched domains
5638 * to the individual cpus
5640 void build_sched_domains(const cpumask_t
*cpu_map
)
5644 struct sched_group
**sched_group_nodes
= NULL
;
5645 struct sched_group
*sched_group_allnodes
= NULL
;
5648 * Allocate the per-node list of sched groups
5650 sched_group_nodes
= kmalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
5652 if (!sched_group_nodes
) {
5653 printk(KERN_WARNING
"Can not alloc sched group node list\n");
5656 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
5660 * Set up domains for cpus specified by the cpu_map.
5662 for_each_cpu_mask(i
, *cpu_map
) {
5664 struct sched_domain
*sd
= NULL
, *p
;
5665 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
5667 cpus_and(nodemask
, nodemask
, *cpu_map
);
5670 if (cpus_weight(*cpu_map
)
5671 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
5672 if (!sched_group_allnodes
) {
5673 sched_group_allnodes
5674 = kmalloc(sizeof(struct sched_group
)
5677 if (!sched_group_allnodes
) {
5679 "Can not alloc allnodes sched group\n");
5682 sched_group_allnodes_bycpu
[i
]
5683 = sched_group_allnodes
;
5685 sd
= &per_cpu(allnodes_domains
, i
);
5686 *sd
= SD_ALLNODES_INIT
;
5687 sd
->span
= *cpu_map
;
5688 group
= cpu_to_allnodes_group(i
);
5689 sd
->groups
= &sched_group_allnodes
[group
];
5694 sd
= &per_cpu(node_domains
, i
);
5696 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
5698 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5702 sd
= &per_cpu(phys_domains
, i
);
5703 group
= cpu_to_phys_group(i
);
5705 sd
->span
= nodemask
;
5707 sd
->groups
= &sched_group_phys
[group
];
5709 #ifdef CONFIG_SCHED_MC
5711 sd
= &per_cpu(core_domains
, i
);
5712 group
= cpu_to_core_group(i
);
5714 sd
->span
= cpu_coregroup_map(i
);
5715 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5717 sd
->groups
= &sched_group_core
[group
];
5720 #ifdef CONFIG_SCHED_SMT
5722 sd
= &per_cpu(cpu_domains
, i
);
5723 group
= cpu_to_cpu_group(i
);
5724 *sd
= SD_SIBLING_INIT
;
5725 sd
->span
= cpu_sibling_map
[i
];
5726 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
5728 sd
->groups
= &sched_group_cpus
[group
];
5732 #ifdef CONFIG_SCHED_SMT
5733 /* Set up CPU (sibling) groups */
5734 for_each_cpu_mask(i
, *cpu_map
) {
5735 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
5736 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
5737 if (i
!= first_cpu(this_sibling_map
))
5740 init_sched_build_groups(sched_group_cpus
, this_sibling_map
,
5745 #ifdef CONFIG_SCHED_MC
5746 /* Set up multi-core groups */
5747 for_each_cpu_mask(i
, *cpu_map
) {
5748 cpumask_t this_core_map
= cpu_coregroup_map(i
);
5749 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
5750 if (i
!= first_cpu(this_core_map
))
5752 init_sched_build_groups(sched_group_core
, this_core_map
,
5753 &cpu_to_core_group
);
5758 /* Set up physical groups */
5759 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5760 cpumask_t nodemask
= node_to_cpumask(i
);
5762 cpus_and(nodemask
, nodemask
, *cpu_map
);
5763 if (cpus_empty(nodemask
))
5766 init_sched_build_groups(sched_group_phys
, nodemask
,
5767 &cpu_to_phys_group
);
5771 /* Set up node groups */
5772 if (sched_group_allnodes
)
5773 init_sched_build_groups(sched_group_allnodes
, *cpu_map
,
5774 &cpu_to_allnodes_group
);
5776 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5777 /* Set up node groups */
5778 struct sched_group
*sg
, *prev
;
5779 cpumask_t nodemask
= node_to_cpumask(i
);
5780 cpumask_t domainspan
;
5781 cpumask_t covered
= CPU_MASK_NONE
;
5784 cpus_and(nodemask
, nodemask
, *cpu_map
);
5785 if (cpus_empty(nodemask
)) {
5786 sched_group_nodes
[i
] = NULL
;
5790 domainspan
= sched_domain_node_span(i
);
5791 cpus_and(domainspan
, domainspan
, *cpu_map
);
5793 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5794 sched_group_nodes
[i
] = sg
;
5795 for_each_cpu_mask(j
, nodemask
) {
5796 struct sched_domain
*sd
;
5797 sd
= &per_cpu(node_domains
, j
);
5799 if (sd
->groups
== NULL
) {
5800 /* Turn off balancing if we have no groups */
5806 "Can not alloc domain group for node %d\n", i
);
5810 sg
->cpumask
= nodemask
;
5811 cpus_or(covered
, covered
, nodemask
);
5814 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
5815 cpumask_t tmp
, notcovered
;
5816 int n
= (i
+ j
) % MAX_NUMNODES
;
5818 cpus_complement(notcovered
, covered
);
5819 cpus_and(tmp
, notcovered
, *cpu_map
);
5820 cpus_and(tmp
, tmp
, domainspan
);
5821 if (cpus_empty(tmp
))
5824 nodemask
= node_to_cpumask(n
);
5825 cpus_and(tmp
, tmp
, nodemask
);
5826 if (cpus_empty(tmp
))
5829 sg
= kmalloc(sizeof(struct sched_group
), GFP_KERNEL
);
5832 "Can not alloc domain group for node %d\n", j
);
5837 cpus_or(covered
, covered
, tmp
);
5841 prev
->next
= sched_group_nodes
[i
];
5845 /* Calculate CPU power for physical packages and nodes */
5846 for_each_cpu_mask(i
, *cpu_map
) {
5848 struct sched_domain
*sd
;
5849 #ifdef CONFIG_SCHED_SMT
5850 sd
= &per_cpu(cpu_domains
, i
);
5851 power
= SCHED_LOAD_SCALE
;
5852 sd
->groups
->cpu_power
= power
;
5854 #ifdef CONFIG_SCHED_MC
5855 sd
= &per_cpu(core_domains
, i
);
5856 power
= SCHED_LOAD_SCALE
+ (cpus_weight(sd
->groups
->cpumask
)-1)
5857 * SCHED_LOAD_SCALE
/ 10;
5858 sd
->groups
->cpu_power
= power
;
5860 sd
= &per_cpu(phys_domains
, i
);
5863 * This has to be < 2 * SCHED_LOAD_SCALE
5864 * Lets keep it SCHED_LOAD_SCALE, so that
5865 * while calculating NUMA group's cpu_power
5867 * numa_group->cpu_power += phys_group->cpu_power;
5869 * See "only add power once for each physical pkg"
5872 sd
->groups
->cpu_power
= SCHED_LOAD_SCALE
;
5874 sd
= &per_cpu(phys_domains
, i
);
5875 power
= SCHED_LOAD_SCALE
+ SCHED_LOAD_SCALE
*
5876 (cpus_weight(sd
->groups
->cpumask
)-1) / 10;
5877 sd
->groups
->cpu_power
= power
;
5882 for (i
= 0; i
< MAX_NUMNODES
; i
++)
5883 init_numa_sched_groups_power(sched_group_nodes
[i
]);
5885 init_numa_sched_groups_power(sched_group_allnodes
);
5888 /* Attach the domains */
5889 for_each_cpu_mask(i
, *cpu_map
) {
5890 struct sched_domain
*sd
;
5891 #ifdef CONFIG_SCHED_SMT
5892 sd
= &per_cpu(cpu_domains
, i
);
5893 #elif defined(CONFIG_SCHED_MC)
5894 sd
= &per_cpu(core_domains
, i
);
5896 sd
= &per_cpu(phys_domains
, i
);
5898 cpu_attach_domain(sd
, i
);
5901 * Tune cache-hot values:
5903 calibrate_migration_costs(cpu_map
);
5906 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
5908 static void arch_init_sched_domains(const cpumask_t
*cpu_map
)
5910 cpumask_t cpu_default_map
;
5913 * Setup mask for cpus without special case scheduling requirements.
5914 * For now this just excludes isolated cpus, but could be used to
5915 * exclude other special cases in the future.
5917 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
5919 build_sched_domains(&cpu_default_map
);
5922 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
5928 for_each_cpu_mask(cpu
, *cpu_map
) {
5929 struct sched_group
*sched_group_allnodes
5930 = sched_group_allnodes_bycpu
[cpu
];
5931 struct sched_group
**sched_group_nodes
5932 = sched_group_nodes_bycpu
[cpu
];
5934 if (sched_group_allnodes
) {
5935 kfree(sched_group_allnodes
);
5936 sched_group_allnodes_bycpu
[cpu
] = NULL
;
5939 if (!sched_group_nodes
)
5942 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
5943 cpumask_t nodemask
= node_to_cpumask(i
);
5944 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
5946 cpus_and(nodemask
, nodemask
, *cpu_map
);
5947 if (cpus_empty(nodemask
))
5957 if (oldsg
!= sched_group_nodes
[i
])
5960 kfree(sched_group_nodes
);
5961 sched_group_nodes_bycpu
[cpu
] = NULL
;
5967 * Detach sched domains from a group of cpus specified in cpu_map
5968 * These cpus will now be attached to the NULL domain
5970 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
5974 for_each_cpu_mask(i
, *cpu_map
)
5975 cpu_attach_domain(NULL
, i
);
5976 synchronize_sched();
5977 arch_destroy_sched_domains(cpu_map
);
5981 * Partition sched domains as specified by the cpumasks below.
5982 * This attaches all cpus from the cpumasks to the NULL domain,
5983 * waits for a RCU quiescent period, recalculates sched
5984 * domain information and then attaches them back to the
5985 * correct sched domains
5986 * Call with hotplug lock held
5988 void partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
5990 cpumask_t change_map
;
5992 cpus_and(*partition1
, *partition1
, cpu_online_map
);
5993 cpus_and(*partition2
, *partition2
, cpu_online_map
);
5994 cpus_or(change_map
, *partition1
, *partition2
);
5996 /* Detach sched domains from all of the affected cpus */
5997 detach_destroy_domains(&change_map
);
5998 if (!cpus_empty(*partition1
))
5999 build_sched_domains(partition1
);
6000 if (!cpus_empty(*partition2
))
6001 build_sched_domains(partition2
);
6004 #ifdef CONFIG_HOTPLUG_CPU
6006 * Force a reinitialization of the sched domains hierarchy. The domains
6007 * and groups cannot be updated in place without racing with the balancing
6008 * code, so we temporarily attach all running cpus to the NULL domain
6009 * which will prevent rebalancing while the sched domains are recalculated.
6011 static int update_sched_domains(struct notifier_block
*nfb
,
6012 unsigned long action
, void *hcpu
)
6015 case CPU_UP_PREPARE
:
6016 case CPU_DOWN_PREPARE
:
6017 detach_destroy_domains(&cpu_online_map
);
6020 case CPU_UP_CANCELED
:
6021 case CPU_DOWN_FAILED
:
6025 * Fall through and re-initialise the domains.
6032 /* The hotplug lock is already held by cpu_up/cpu_down */
6033 arch_init_sched_domains(&cpu_online_map
);
6039 void __init
sched_init_smp(void)
6042 arch_init_sched_domains(&cpu_online_map
);
6043 unlock_cpu_hotplug();
6044 /* XXX: Theoretical race here - CPU may be hotplugged now */
6045 hotcpu_notifier(update_sched_domains
, 0);
6048 void __init
sched_init_smp(void)
6051 #endif /* CONFIG_SMP */
6053 int in_sched_functions(unsigned long addr
)
6055 /* Linker adds these: start and end of __sched functions */
6056 extern char __sched_text_start
[], __sched_text_end
[];
6057 return in_lock_functions(addr
) ||
6058 (addr
>= (unsigned long)__sched_text_start
6059 && addr
< (unsigned long)__sched_text_end
);
6062 void __init
sched_init(void)
6067 for_each_possible_cpu(i
) {
6068 prio_array_t
*array
;
6071 spin_lock_init(&rq
->lock
);
6073 rq
->active
= rq
->arrays
;
6074 rq
->expired
= rq
->arrays
+ 1;
6075 rq
->best_expired_prio
= MAX_PRIO
;
6079 for (j
= 1; j
< 3; j
++)
6080 rq
->cpu_load
[j
] = 0;
6081 rq
->active_balance
= 0;
6083 rq
->migration_thread
= NULL
;
6084 INIT_LIST_HEAD(&rq
->migration_queue
);
6086 atomic_set(&rq
->nr_iowait
, 0);
6088 for (j
= 0; j
< 2; j
++) {
6089 array
= rq
->arrays
+ j
;
6090 for (k
= 0; k
< MAX_PRIO
; k
++) {
6091 INIT_LIST_HEAD(array
->queue
+ k
);
6092 __clear_bit(k
, array
->bitmap
);
6094 // delimiter for bitsearch
6095 __set_bit(MAX_PRIO
, array
->bitmap
);
6100 * The boot idle thread does lazy MMU switching as well:
6102 atomic_inc(&init_mm
.mm_count
);
6103 enter_lazy_tlb(&init_mm
, current
);
6106 * Make us the idle thread. Technically, schedule() should not be
6107 * called from this thread, however somewhere below it might be,
6108 * but because we are the idle thread, we just pick up running again
6109 * when this runqueue becomes "idle".
6111 init_idle(current
, smp_processor_id());
6114 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6115 void __might_sleep(char *file
, int line
)
6117 #if defined(in_atomic)
6118 static unsigned long prev_jiffy
; /* ratelimiting */
6120 if ((in_atomic() || irqs_disabled()) &&
6121 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6122 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6124 prev_jiffy
= jiffies
;
6125 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6126 " context at %s:%d\n", file
, line
);
6127 printk("in_atomic():%d, irqs_disabled():%d\n",
6128 in_atomic(), irqs_disabled());
6133 EXPORT_SYMBOL(__might_sleep
);
6136 #ifdef CONFIG_MAGIC_SYSRQ
6137 void normalize_rt_tasks(void)
6139 struct task_struct
*p
;
6140 prio_array_t
*array
;
6141 unsigned long flags
;
6144 read_lock_irq(&tasklist_lock
);
6145 for_each_process(p
) {
6149 rq
= task_rq_lock(p
, &flags
);
6153 deactivate_task(p
, task_rq(p
));
6154 __setscheduler(p
, SCHED_NORMAL
, 0);
6156 __activate_task(p
, task_rq(p
));
6157 resched_task(rq
->curr
);
6160 task_rq_unlock(rq
, &flags
);
6162 read_unlock_irq(&tasklist_lock
);
6165 #endif /* CONFIG_MAGIC_SYSRQ */
6169 * These functions are only useful for the IA64 MCA handling.
6171 * They can only be called when the whole system has been
6172 * stopped - every CPU needs to be quiescent, and no scheduling
6173 * activity can take place. Using them for anything else would
6174 * be a serious bug, and as a result, they aren't even visible
6175 * under any other configuration.
6179 * curr_task - return the current task for a given cpu.
6180 * @cpu: the processor in question.
6182 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6184 task_t
*curr_task(int cpu
)
6186 return cpu_curr(cpu
);
6190 * set_curr_task - set the current task for a given cpu.
6191 * @cpu: the processor in question.
6192 * @p: the task pointer to set.
6194 * Description: This function must only be used when non-maskable interrupts
6195 * are serviced on a separate stack. It allows the architecture to switch the
6196 * notion of the current task on a cpu in a non-blocking manner. This function
6197 * must be called with all CPU's synchronized, and interrupts disabled, the
6198 * and caller must save the original value of the current task (see
6199 * curr_task() above) and restore that value before reenabling interrupts and
6200 * re-starting the system.
6202 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6204 void set_curr_task(int cpu
, task_t
*p
)