ia64/linux-2.6.18-xen.hg

view kernel/sched.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents 3e8752eb6d9c
children
line source
1 /*
2 * kernel/sched.c
3 *
4 * Kernel scheduler and related syscalls
5 *
6 * Copyright (C) 1991-2002 Linus Torvalds
7 *
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
11 * by Andrea Arcangeli
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
19 */
21 #include <linux/mm.h>
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/debug_locks.h>
34 #include <linux/security.h>
35 #include <linux/notifier.h>
36 #include <linux/profile.h>
37 #include <linux/suspend.h>
38 #include <linux/vmalloc.h>
39 #include <linux/blkdev.h>
40 #include <linux/delay.h>
41 #include <linux/smp.h>
42 #include <linux/threads.h>
43 #include <linux/timer.h>
44 #include <linux/rcupdate.h>
45 #include <linux/cpu.h>
46 #include <linux/cpuset.h>
47 #include <linux/percpu.h>
48 #include <linux/kthread.h>
49 #include <linux/seq_file.h>
50 #include <linux/syscalls.h>
51 #include <linux/times.h>
52 #include <linux/acct.h>
53 #include <linux/kprobes.h>
54 #include <linux/delayacct.h>
55 #include <asm/tlb.h>
57 #include <asm/unistd.h>
59 /*
60 * Convert user-nice values [ -20 ... 0 ... 19 ]
61 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
62 * and back.
63 */
64 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
65 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
66 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
68 /*
69 * 'User priority' is the nice value converted to something we
70 * can work with better when scaling various scheduler parameters,
71 * it's a [ 0 ... 39 ] range.
72 */
73 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
74 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
75 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
77 /*
78 * Some helpers for converting nanosecond timing to jiffy resolution
79 */
80 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
81 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
83 /*
84 * These are the 'tuning knobs' of the scheduler:
85 *
86 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
87 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
88 * Timeslices get refilled after they expire.
89 */
90 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
91 #define DEF_TIMESLICE (100 * HZ / 1000)
92 #define ON_RUNQUEUE_WEIGHT 30
93 #define CHILD_PENALTY 95
94 #define PARENT_PENALTY 100
95 #define EXIT_WEIGHT 3
96 #define PRIO_BONUS_RATIO 25
97 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
98 #define INTERACTIVE_DELTA 2
99 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
100 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
101 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
103 /*
104 * If a task is 'interactive' then we reinsert it in the active
105 * array after it has expired its current timeslice. (it will not
106 * continue to run immediately, it will still roundrobin with
107 * other interactive tasks.)
108 *
109 * This part scales the interactivity limit depending on niceness.
110 *
111 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
112 * Here are a few examples of different nice levels:
113 *
114 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
115 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
116 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
117 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
118 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
119 *
120 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
121 * priority range a task can explore, a value of '1' means the
122 * task is rated interactive.)
123 *
124 * Ie. nice +19 tasks can never get 'interactive' enough to be
125 * reinserted into the active array. And only heavily CPU-hog nice -20
126 * tasks will be expired. Default nice 0 tasks are somewhere between,
127 * it takes some effort for them to get interactive, but it's not
128 * too hard.
129 */
131 #define CURRENT_BONUS(p) \
132 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
133 MAX_SLEEP_AVG)
135 #define GRANULARITY (10 * HZ / 1000 ? : 1)
137 #ifdef CONFIG_SMP
138 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
139 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
140 num_online_cpus())
141 #else
142 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
143 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
144 #endif
146 #define SCALE(v1,v1_max,v2_max) \
147 (v1) * (v2_max) / (v1_max)
149 #define DELTA(p) \
150 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
151 INTERACTIVE_DELTA)
153 #define TASK_INTERACTIVE(p) \
154 ((p)->prio <= (p)->static_prio - DELTA(p))
156 #define INTERACTIVE_SLEEP(p) \
157 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
158 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
160 #define TASK_PREEMPTS_CURR(p, rq) \
161 ((p)->prio < (rq)->curr->prio)
163 /*
164 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
165 * to time slice values: [800ms ... 100ms ... 5ms]
166 *
167 * The higher a thread's priority, the bigger timeslices
168 * it gets during one round of execution. But even the lowest
169 * priority thread gets MIN_TIMESLICE worth of execution time.
170 */
172 #define SCALE_PRIO(x, prio) \
173 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
175 static unsigned int static_prio_timeslice(int static_prio)
176 {
177 if (static_prio < NICE_TO_PRIO(0))
178 return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
179 else
180 return SCALE_PRIO(DEF_TIMESLICE, static_prio);
181 }
183 static inline unsigned int task_timeslice(struct task_struct *p)
184 {
185 return static_prio_timeslice(p->static_prio);
186 }
188 /*
189 * These are the runqueue data structures:
190 */
192 struct prio_array {
193 unsigned int nr_active;
194 DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */
195 struct list_head queue[MAX_PRIO];
196 };
198 /*
199 * This is the main, per-CPU runqueue data structure.
200 *
201 * Locking rule: those places that want to lock multiple runqueues
202 * (such as the load balancing or the thread migration code), lock
203 * acquire operations must be ordered by ascending &runqueue.
204 */
205 struct rq {
206 spinlock_t lock;
208 /*
209 * nr_running and cpu_load should be in the same cacheline because
210 * remote CPUs use both these fields when doing load calculation.
211 */
212 unsigned long nr_running;
213 unsigned long raw_weighted_load;
214 #ifdef CONFIG_SMP
215 unsigned long cpu_load[3];
216 #endif
217 unsigned long long nr_switches;
219 /*
220 * This is part of a global counter where only the total sum
221 * over all CPUs matters. A task can increase this counter on
222 * one CPU and if it got migrated afterwards it may decrease
223 * it on another CPU. Always updated under the runqueue lock:
224 */
225 unsigned long nr_uninterruptible;
227 unsigned long expired_timestamp;
228 unsigned long long timestamp_last_tick;
229 struct task_struct *curr, *idle;
230 struct mm_struct *prev_mm;
231 struct prio_array *active, *expired, arrays[2];
232 int best_expired_prio;
233 atomic_t nr_iowait;
235 #ifdef CONFIG_SMP
236 struct sched_domain *sd;
238 /* For active balancing */
239 int active_balance;
240 int push_cpu;
241 int cpu; /* cpu of this runqueue */
243 struct task_struct *migration_thread;
244 struct list_head migration_queue;
245 #endif
247 #ifdef CONFIG_SCHEDSTATS
248 /* latency stats */
249 struct sched_info rq_sched_info;
251 /* sys_sched_yield() stats */
252 unsigned long yld_exp_empty;
253 unsigned long yld_act_empty;
254 unsigned long yld_both_empty;
255 unsigned long yld_cnt;
257 /* schedule() stats */
258 unsigned long sched_switch;
259 unsigned long sched_cnt;
260 unsigned long sched_goidle;
262 /* try_to_wake_up() stats */
263 unsigned long ttwu_cnt;
264 unsigned long ttwu_local;
265 #endif
266 struct lock_class_key rq_lock_key;
267 };
269 static DEFINE_PER_CPU(struct rq, runqueues);
271 static inline int cpu_of(struct rq *rq)
272 {
273 #ifdef CONFIG_SMP
274 return rq->cpu;
275 #else
276 return 0;
277 #endif
278 }
280 /*
281 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
282 * See detach_destroy_domains: synchronize_sched for details.
283 *
284 * The domain tree of any CPU may only be accessed from within
285 * preempt-disabled sections.
286 */
287 #define for_each_domain(cpu, __sd) \
288 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
290 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
291 #define this_rq() (&__get_cpu_var(runqueues))
292 #define task_rq(p) cpu_rq(task_cpu(p))
293 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
295 #ifndef prepare_arch_switch
296 # define prepare_arch_switch(next) do { } while (0)
297 #endif
298 #ifndef finish_arch_switch
299 # define finish_arch_switch(prev) do { } while (0)
300 #endif
302 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
303 static inline int task_running(struct rq *rq, struct task_struct *p)
304 {
305 return rq->curr == p;
306 }
308 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
309 {
310 }
312 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
313 {
314 #ifdef CONFIG_DEBUG_SPINLOCK
315 /* this is a valid case when another task releases the spinlock */
316 rq->lock.owner = current;
317 #endif
318 /*
319 * If we are tracking spinlock dependencies then we have to
320 * fix up the runqueue lock - which gets 'carried over' from
321 * prev into current:
322 */
323 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
325 spin_unlock_irq(&rq->lock);
326 }
328 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
329 static inline int task_running(struct rq *rq, struct task_struct *p)
330 {
331 #ifdef CONFIG_SMP
332 return p->oncpu;
333 #else
334 return rq->curr == p;
335 #endif
336 }
338 static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
339 {
340 #ifdef CONFIG_SMP
341 /*
342 * We can optimise this out completely for !SMP, because the
343 * SMP rebalancing from interrupt is the only thing that cares
344 * here.
345 */
346 next->oncpu = 1;
347 #endif
348 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
349 spin_unlock_irq(&rq->lock);
350 #else
351 spin_unlock(&rq->lock);
352 #endif
353 }
355 static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
356 {
357 #ifdef CONFIG_SMP
358 /*
359 * After ->oncpu is cleared, the task can be moved to a different CPU.
360 * We must ensure this doesn't happen until the switch is completely
361 * finished.
362 */
363 smp_wmb();
364 prev->oncpu = 0;
365 #endif
366 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
367 local_irq_enable();
368 #endif
369 }
370 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
372 /*
373 * __task_rq_lock - lock the runqueue a given task resides on.
374 * Must be called interrupts disabled.
375 */
376 static inline struct rq *__task_rq_lock(struct task_struct *p)
377 __acquires(rq->lock)
378 {
379 struct rq *rq;
381 repeat_lock_task:
382 rq = task_rq(p);
383 spin_lock(&rq->lock);
384 if (unlikely(rq != task_rq(p))) {
385 spin_unlock(&rq->lock);
386 goto repeat_lock_task;
387 }
388 return rq;
389 }
391 /*
392 * task_rq_lock - lock the runqueue a given task resides on and disable
393 * interrupts. Note the ordering: we can safely lookup the task_rq without
394 * explicitly disabling preemption.
395 */
396 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
397 __acquires(rq->lock)
398 {
399 struct rq *rq;
401 repeat_lock_task:
402 local_irq_save(*flags);
403 rq = task_rq(p);
404 spin_lock(&rq->lock);
405 if (unlikely(rq != task_rq(p))) {
406 spin_unlock_irqrestore(&rq->lock, *flags);
407 goto repeat_lock_task;
408 }
409 return rq;
410 }
412 static inline void __task_rq_unlock(struct rq *rq)
413 __releases(rq->lock)
414 {
415 spin_unlock(&rq->lock);
416 }
418 static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
419 __releases(rq->lock)
420 {
421 spin_unlock_irqrestore(&rq->lock, *flags);
422 }
424 #ifdef CONFIG_SCHEDSTATS
425 /*
426 * bump this up when changing the output format or the meaning of an existing
427 * format, so that tools can adapt (or abort)
428 */
429 #define SCHEDSTAT_VERSION 12
431 static int show_schedstat(struct seq_file *seq, void *v)
432 {
433 int cpu;
435 seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
436 seq_printf(seq, "timestamp %lu\n", jiffies);
437 for_each_online_cpu(cpu) {
438 struct rq *rq = cpu_rq(cpu);
439 #ifdef CONFIG_SMP
440 struct sched_domain *sd;
441 int dcnt = 0;
442 #endif
444 /* runqueue-specific stats */
445 seq_printf(seq,
446 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
447 cpu, rq->yld_both_empty,
448 rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
449 rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
450 rq->ttwu_cnt, rq->ttwu_local,
451 rq->rq_sched_info.cpu_time,
452 rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
454 seq_printf(seq, "\n");
456 #ifdef CONFIG_SMP
457 /* domain-specific stats */
458 preempt_disable();
459 for_each_domain(cpu, sd) {
460 enum idle_type itype;
461 char mask_str[NR_CPUS];
463 cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
464 seq_printf(seq, "domain%d %s", dcnt++, mask_str);
465 for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
466 itype++) {
467 seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu",
468 sd->lb_cnt[itype],
469 sd->lb_balanced[itype],
470 sd->lb_failed[itype],
471 sd->lb_imbalance[itype],
472 sd->lb_gained[itype],
473 sd->lb_hot_gained[itype],
474 sd->lb_nobusyq[itype],
475 sd->lb_nobusyg[itype]);
476 }
477 seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
478 sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
479 sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
480 sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
481 sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
482 }
483 preempt_enable();
484 #endif
485 }
486 return 0;
487 }
489 static int schedstat_open(struct inode *inode, struct file *file)
490 {
491 unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
492 char *buf = kmalloc(size, GFP_KERNEL);
493 struct seq_file *m;
494 int res;
496 if (!buf)
497 return -ENOMEM;
498 res = single_open(file, show_schedstat, NULL);
499 if (!res) {
500 m = file->private_data;
501 m->buf = buf;
502 m->size = size;
503 } else
504 kfree(buf);
505 return res;
506 }
508 struct file_operations proc_schedstat_operations = {
509 .open = schedstat_open,
510 .read = seq_read,
511 .llseek = seq_lseek,
512 .release = single_release,
513 };
515 /*
516 * Expects runqueue lock to be held for atomicity of update
517 */
518 static inline void
519 rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
520 {
521 if (rq) {
522 rq->rq_sched_info.run_delay += delta_jiffies;
523 rq->rq_sched_info.pcnt++;
524 }
525 }
527 /*
528 * Expects runqueue lock to be held for atomicity of update
529 */
530 static inline void
531 rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
532 {
533 if (rq)
534 rq->rq_sched_info.cpu_time += delta_jiffies;
535 }
536 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
537 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
538 #else /* !CONFIG_SCHEDSTATS */
539 static inline void
540 rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
541 {}
542 static inline void
543 rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
544 {}
545 # define schedstat_inc(rq, field) do { } while (0)
546 # define schedstat_add(rq, field, amt) do { } while (0)
547 #endif
549 /*
550 * rq_lock - lock a given runqueue and disable interrupts.
551 */
552 static inline struct rq *this_rq_lock(void)
553 __acquires(rq->lock)
554 {
555 struct rq *rq;
557 local_irq_disable();
558 rq = this_rq();
559 spin_lock(&rq->lock);
561 return rq;
562 }
564 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
565 /*
566 * Called when a process is dequeued from the active array and given
567 * the cpu. We should note that with the exception of interactive
568 * tasks, the expired queue will become the active queue after the active
569 * queue is empty, without explicitly dequeuing and requeuing tasks in the
570 * expired queue. (Interactive tasks may be requeued directly to the
571 * active queue, thus delaying tasks in the expired queue from running;
572 * see scheduler_tick()).
573 *
574 * This function is only called from sched_info_arrive(), rather than
575 * dequeue_task(). Even though a task may be queued and dequeued multiple
576 * times as it is shuffled about, we're really interested in knowing how
577 * long it was from the *first* time it was queued to the time that it
578 * finally hit a cpu.
579 */
580 static inline void sched_info_dequeued(struct task_struct *t)
581 {
582 t->sched_info.last_queued = 0;
583 }
585 /*
586 * Called when a task finally hits the cpu. We can now calculate how
587 * long it was waiting to run. We also note when it began so that we
588 * can keep stats on how long its timeslice is.
589 */
590 static void sched_info_arrive(struct task_struct *t)
591 {
592 unsigned long now = jiffies, delta_jiffies = 0;
594 if (t->sched_info.last_queued)
595 delta_jiffies = now - t->sched_info.last_queued;
596 sched_info_dequeued(t);
597 t->sched_info.run_delay += delta_jiffies;
598 t->sched_info.last_arrival = now;
599 t->sched_info.pcnt++;
601 rq_sched_info_arrive(task_rq(t), delta_jiffies);
602 }
604 /*
605 * Called when a process is queued into either the active or expired
606 * array. The time is noted and later used to determine how long we
607 * had to wait for us to reach the cpu. Since the expired queue will
608 * become the active queue after active queue is empty, without dequeuing
609 * and requeuing any tasks, we are interested in queuing to either. It
610 * is unusual but not impossible for tasks to be dequeued and immediately
611 * requeued in the same or another array: this can happen in sched_yield(),
612 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
613 * to runqueue.
614 *
615 * This function is only called from enqueue_task(), but also only updates
616 * the timestamp if it is already not set. It's assumed that
617 * sched_info_dequeued() will clear that stamp when appropriate.
618 */
619 static inline void sched_info_queued(struct task_struct *t)
620 {
621 if (unlikely(sched_info_on()))
622 if (!t->sched_info.last_queued)
623 t->sched_info.last_queued = jiffies;
624 }
626 /*
627 * Called when a process ceases being the active-running process, either
628 * voluntarily or involuntarily. Now we can calculate how long we ran.
629 */
630 static inline void sched_info_depart(struct task_struct *t)
631 {
632 unsigned long delta_jiffies = jiffies - t->sched_info.last_arrival;
634 t->sched_info.cpu_time += delta_jiffies;
635 rq_sched_info_depart(task_rq(t), delta_jiffies);
636 }
638 /*
639 * Called when tasks are switched involuntarily due, typically, to expiring
640 * their time slice. (This may also be called when switching to or from
641 * the idle task.) We are only called when prev != next.
642 */
643 static inline void
644 __sched_info_switch(struct task_struct *prev, struct task_struct *next)
645 {
646 struct rq *rq = task_rq(prev);
648 /*
649 * prev now departs the cpu. It's not interesting to record
650 * stats about how efficient we were at scheduling the idle
651 * process, however.
652 */
653 if (prev != rq->idle)
654 sched_info_depart(prev);
656 if (next != rq->idle)
657 sched_info_arrive(next);
658 }
659 static inline void
660 sched_info_switch(struct task_struct *prev, struct task_struct *next)
661 {
662 if (unlikely(sched_info_on()))
663 __sched_info_switch(prev, next);
664 }
665 #else
666 #define sched_info_queued(t) do { } while (0)
667 #define sched_info_switch(t, next) do { } while (0)
668 #endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
670 /*
671 * Adding/removing a task to/from a priority array:
672 */
673 static void dequeue_task(struct task_struct *p, struct prio_array *array)
674 {
675 array->nr_active--;
676 list_del(&p->run_list);
677 if (list_empty(array->queue + p->prio))
678 __clear_bit(p->prio, array->bitmap);
679 }
681 static void enqueue_task(struct task_struct *p, struct prio_array *array)
682 {
683 sched_info_queued(p);
684 list_add_tail(&p->run_list, array->queue + p->prio);
685 __set_bit(p->prio, array->bitmap);
686 array->nr_active++;
687 p->array = array;
688 }
690 /*
691 * Put task to the end of the run list without the overhead of dequeue
692 * followed by enqueue.
693 */
694 static void requeue_task(struct task_struct *p, struct prio_array *array)
695 {
696 list_move_tail(&p->run_list, array->queue + p->prio);
697 }
699 static inline void
700 enqueue_task_head(struct task_struct *p, struct prio_array *array)
701 {
702 list_add(&p->run_list, array->queue + p->prio);
703 __set_bit(p->prio, array->bitmap);
704 array->nr_active++;
705 p->array = array;
706 }
708 /*
709 * __normal_prio - return the priority that is based on the static
710 * priority but is modified by bonuses/penalties.
711 *
712 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
713 * into the -5 ... 0 ... +5 bonus/penalty range.
714 *
715 * We use 25% of the full 0...39 priority range so that:
716 *
717 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
718 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
719 *
720 * Both properties are important to certain workloads.
721 */
723 static inline int __normal_prio(struct task_struct *p)
724 {
725 int bonus, prio;
727 bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
729 prio = p->static_prio - bonus;
730 if (prio < MAX_RT_PRIO)
731 prio = MAX_RT_PRIO;
732 if (prio > MAX_PRIO-1)
733 prio = MAX_PRIO-1;
734 return prio;
735 }
737 /*
738 * To aid in avoiding the subversion of "niceness" due to uneven distribution
739 * of tasks with abnormal "nice" values across CPUs the contribution that
740 * each task makes to its run queue's load is weighted according to its
741 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
742 * scaled version of the new time slice allocation that they receive on time
743 * slice expiry etc.
744 */
746 /*
747 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
748 * If static_prio_timeslice() is ever changed to break this assumption then
749 * this code will need modification
750 */
751 #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
752 #define LOAD_WEIGHT(lp) \
753 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
754 #define PRIO_TO_LOAD_WEIGHT(prio) \
755 LOAD_WEIGHT(static_prio_timeslice(prio))
756 #define RTPRIO_TO_LOAD_WEIGHT(rp) \
757 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
759 static void set_load_weight(struct task_struct *p)
760 {
761 if (has_rt_policy(p)) {
762 #ifdef CONFIG_SMP
763 if (p == task_rq(p)->migration_thread)
764 /*
765 * The migration thread does the actual balancing.
766 * Giving its load any weight will skew balancing
767 * adversely.
768 */
769 p->load_weight = 0;
770 else
771 #endif
772 p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
773 } else
774 p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
775 }
777 static inline void
778 inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
779 {
780 rq->raw_weighted_load += p->load_weight;
781 }
783 static inline void
784 dec_raw_weighted_load(struct rq *rq, const struct task_struct *p)
785 {
786 rq->raw_weighted_load -= p->load_weight;
787 }
789 static inline void inc_nr_running(struct task_struct *p, struct rq *rq)
790 {
791 rq->nr_running++;
792 inc_raw_weighted_load(rq, p);
793 }
795 static inline void dec_nr_running(struct task_struct *p, struct rq *rq)
796 {
797 rq->nr_running--;
798 dec_raw_weighted_load(rq, p);
799 }
801 /*
802 * Calculate the expected normal priority: i.e. priority
803 * without taking RT-inheritance into account. Might be
804 * boosted by interactivity modifiers. Changes upon fork,
805 * setprio syscalls, and whenever the interactivity
806 * estimator recalculates.
807 */
808 static inline int normal_prio(struct task_struct *p)
809 {
810 int prio;
812 if (has_rt_policy(p))
813 prio = MAX_RT_PRIO-1 - p->rt_priority;
814 else
815 prio = __normal_prio(p);
816 return prio;
817 }
819 /*
820 * Calculate the current priority, i.e. the priority
821 * taken into account by the scheduler. This value might
822 * be boosted by RT tasks, or might be boosted by
823 * interactivity modifiers. Will be RT if the task got
824 * RT-boosted. If not then it returns p->normal_prio.
825 */
826 static int effective_prio(struct task_struct *p)
827 {
828 p->normal_prio = normal_prio(p);
829 /*
830 * If we are RT tasks or we were boosted to RT priority,
831 * keep the priority unchanged. Otherwise, update priority
832 * to the normal priority:
833 */
834 if (!rt_prio(p->prio))
835 return p->normal_prio;
836 return p->prio;
837 }
839 /*
840 * __activate_task - move a task to the runqueue.
841 */
842 static void __activate_task(struct task_struct *p, struct rq *rq)
843 {
844 struct prio_array *target = rq->active;
846 if (batch_task(p))
847 target = rq->expired;
848 enqueue_task(p, target);
849 inc_nr_running(p, rq);
850 }
852 /*
853 * __activate_idle_task - move idle task to the _front_ of runqueue.
854 */
855 static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
856 {
857 enqueue_task_head(p, rq->active);
858 inc_nr_running(p, rq);
859 }
861 /*
862 * Recalculate p->normal_prio and p->prio after having slept,
863 * updating the sleep-average too:
864 */
865 static int recalc_task_prio(struct task_struct *p, unsigned long long now)
866 {
867 /* Caller must always ensure 'now >= p->timestamp' */
868 unsigned long sleep_time = now - p->timestamp;
870 if (batch_task(p))
871 sleep_time = 0;
873 if (likely(sleep_time > 0)) {
874 /*
875 * This ceiling is set to the lowest priority that would allow
876 * a task to be reinserted into the active array on timeslice
877 * completion.
878 */
879 unsigned long ceiling = INTERACTIVE_SLEEP(p);
881 if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
882 /*
883 * Prevents user tasks from achieving best priority
884 * with one single large enough sleep.
885 */
886 p->sleep_avg = ceiling;
887 /*
888 * Using INTERACTIVE_SLEEP() as a ceiling places a
889 * nice(0) task 1ms sleep away from promotion, and
890 * gives it 700ms to round-robin with no chance of
891 * being demoted. This is more than generous, so
892 * mark this sleep as non-interactive to prevent the
893 * on-runqueue bonus logic from intervening should
894 * this task not receive cpu immediately.
895 */
896 p->sleep_type = SLEEP_NONINTERACTIVE;
897 } else {
898 /*
899 * Tasks waking from uninterruptible sleep are
900 * limited in their sleep_avg rise as they
901 * are likely to be waiting on I/O
902 */
903 if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) {
904 if (p->sleep_avg >= ceiling)
905 sleep_time = 0;
906 else if (p->sleep_avg + sleep_time >=
907 ceiling) {
908 p->sleep_avg = ceiling;
909 sleep_time = 0;
910 }
911 }
913 /*
914 * This code gives a bonus to interactive tasks.
915 *
916 * The boost works by updating the 'average sleep time'
917 * value here, based on ->timestamp. The more time a
918 * task spends sleeping, the higher the average gets -
919 * and the higher the priority boost gets as well.
920 */
921 p->sleep_avg += sleep_time;
923 }
924 if (p->sleep_avg > NS_MAX_SLEEP_AVG)
925 p->sleep_avg = NS_MAX_SLEEP_AVG;
926 }
928 return effective_prio(p);
929 }
931 /*
932 * activate_task - move a task to the runqueue and do priority recalculation
933 *
934 * Update all the scheduling statistics stuff. (sleep average
935 * calculation, priority modifiers, etc.)
936 */
937 static void activate_task(struct task_struct *p, struct rq *rq, int local)
938 {
939 unsigned long long now;
941 now = sched_clock();
942 #ifdef CONFIG_SMP
943 if (!local) {
944 /* Compensate for drifting sched_clock */
945 struct rq *this_rq = this_rq();
946 now = (now - this_rq->timestamp_last_tick)
947 + rq->timestamp_last_tick;
948 }
949 #endif
951 if (!rt_task(p))
952 p->prio = recalc_task_prio(p, now);
954 /*
955 * This checks to make sure it's not an uninterruptible task
956 * that is now waking up.
957 */
958 if (p->sleep_type == SLEEP_NORMAL) {
959 /*
960 * Tasks which were woken up by interrupts (ie. hw events)
961 * are most likely of interactive nature. So we give them
962 * the credit of extending their sleep time to the period
963 * of time they spend on the runqueue, waiting for execution
964 * on a CPU, first time around:
965 */
966 if (in_interrupt())
967 p->sleep_type = SLEEP_INTERRUPTED;
968 else {
969 /*
970 * Normal first-time wakeups get a credit too for
971 * on-runqueue time, but it will be weighted down:
972 */
973 p->sleep_type = SLEEP_INTERACTIVE;
974 }
975 }
976 p->timestamp = now;
978 __activate_task(p, rq);
979 }
981 /*
982 * deactivate_task - remove a task from the runqueue.
983 */
984 static void deactivate_task(struct task_struct *p, struct rq *rq)
985 {
986 dec_nr_running(p, rq);
987 dequeue_task(p, p->array);
988 p->array = NULL;
989 }
991 /*
992 * resched_task - mark a task 'to be rescheduled now'.
993 *
994 * On UP this means the setting of the need_resched flag, on SMP it
995 * might also involve a cross-CPU call to trigger the scheduler on
996 * the target CPU.
997 */
998 #ifdef CONFIG_SMP
1000 #ifndef tsk_is_polling
1001 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1002 #endif
1004 static void resched_task(struct task_struct *p)
1006 int cpu;
1008 assert_spin_locked(&task_rq(p)->lock);
1010 if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
1011 return;
1013 set_tsk_thread_flag(p, TIF_NEED_RESCHED);
1015 cpu = task_cpu(p);
1016 if (cpu == smp_processor_id())
1017 return;
1019 /* NEED_RESCHED must be visible before we test polling */
1020 smp_mb();
1021 if (!tsk_is_polling(p))
1022 smp_send_reschedule(cpu);
1024 #else
1025 static inline void resched_task(struct task_struct *p)
1027 assert_spin_locked(&task_rq(p)->lock);
1028 set_tsk_need_resched(p);
1030 #endif
1032 /**
1033 * task_curr - is this task currently executing on a CPU?
1034 * @p: the task in question.
1035 */
1036 inline int task_curr(const struct task_struct *p)
1038 return cpu_curr(task_cpu(p)) == p;
1041 /* Used instead of source_load when we know the type == 0 */
1042 unsigned long weighted_cpuload(const int cpu)
1044 return cpu_rq(cpu)->raw_weighted_load;
1047 #ifdef CONFIG_SMP
1048 struct migration_req {
1049 struct list_head list;
1051 struct task_struct *task;
1052 int dest_cpu;
1054 struct completion done;
1055 };
1057 /*
1058 * The task's runqueue lock must be held.
1059 * Returns true if you have to wait for migration thread.
1060 */
1061 static int
1062 migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1064 struct rq *rq = task_rq(p);
1066 /*
1067 * If the task is not on a runqueue (and not running), then
1068 * it is sufficient to simply update the task's cpu field.
1069 */
1070 if (!p->array && !task_running(rq, p)) {
1071 set_task_cpu(p, dest_cpu);
1072 return 0;
1075 init_completion(&req->done);
1076 req->task = p;
1077 req->dest_cpu = dest_cpu;
1078 list_add(&req->list, &rq->migration_queue);
1080 return 1;
1083 /*
1084 * wait_task_inactive - wait for a thread to unschedule.
1086 * The caller must ensure that the task *will* unschedule sometime soon,
1087 * else this function might spin for a *long* time. This function can't
1088 * be called with interrupts off, or it may introduce deadlock with
1089 * smp_call_function() if an IPI is sent by the same process we are
1090 * waiting to become inactive.
1091 */
1092 void wait_task_inactive(struct task_struct *p)
1094 unsigned long flags;
1095 struct rq *rq;
1096 int preempted;
1098 repeat:
1099 rq = task_rq_lock(p, &flags);
1100 /* Must be off runqueue entirely, not preempted. */
1101 if (unlikely(p->array || task_running(rq, p))) {
1102 /* If it's preempted, we yield. It could be a while. */
1103 preempted = !task_running(rq, p);
1104 task_rq_unlock(rq, &flags);
1105 cpu_relax();
1106 if (preempted)
1107 yield();
1108 goto repeat;
1110 task_rq_unlock(rq, &flags);
1113 /***
1114 * kick_process - kick a running thread to enter/exit the kernel
1115 * @p: the to-be-kicked thread
1117 * Cause a process which is running on another CPU to enter
1118 * kernel-mode, without any delay. (to get signals handled.)
1120 * NOTE: this function doesnt have to take the runqueue lock,
1121 * because all it wants to ensure is that the remote task enters
1122 * the kernel. If the IPI races and the task has been migrated
1123 * to another CPU then no harm is done and the purpose has been
1124 * achieved as well.
1125 */
1126 void kick_process(struct task_struct *p)
1128 int cpu;
1130 preempt_disable();
1131 cpu = task_cpu(p);
1132 if ((cpu != smp_processor_id()) && task_curr(p))
1133 smp_send_reschedule(cpu);
1134 preempt_enable();
1137 /*
1138 * Return a low guess at the load of a migration-source cpu weighted
1139 * according to the scheduling class and "nice" value.
1141 * We want to under-estimate the load of migration sources, to
1142 * balance conservatively.
1143 */
1144 static inline unsigned long source_load(int cpu, int type)
1146 struct rq *rq = cpu_rq(cpu);
1148 if (type == 0)
1149 return rq->raw_weighted_load;
1151 return min(rq->cpu_load[type-1], rq->raw_weighted_load);
1154 /*
1155 * Return a high guess at the load of a migration-target cpu weighted
1156 * according to the scheduling class and "nice" value.
1157 */
1158 static inline unsigned long target_load(int cpu, int type)
1160 struct rq *rq = cpu_rq(cpu);
1162 if (type == 0)
1163 return rq->raw_weighted_load;
1165 return max(rq->cpu_load[type-1], rq->raw_weighted_load);
1168 /*
1169 * Return the average load per task on the cpu's run queue
1170 */
1171 static inline unsigned long cpu_avg_load_per_task(int cpu)
1173 struct rq *rq = cpu_rq(cpu);
1174 unsigned long n = rq->nr_running;
1176 return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE;
1179 /*
1180 * find_idlest_group finds and returns the least busy CPU group within the
1181 * domain.
1182 */
1183 static struct sched_group *
1184 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
1186 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1187 unsigned long min_load = ULONG_MAX, this_load = 0;
1188 int load_idx = sd->forkexec_idx;
1189 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1191 do {
1192 unsigned long load, avg_load;
1193 int local_group;
1194 int i;
1196 /* Skip over this group if it has no CPUs allowed */
1197 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
1198 goto nextgroup;
1200 local_group = cpu_isset(this_cpu, group->cpumask);
1202 /* Tally up the load of all CPUs in the group */
1203 avg_load = 0;
1205 for_each_cpu_mask(i, group->cpumask) {
1206 /* Bias balancing toward cpus of our domain */
1207 if (local_group)
1208 load = source_load(i, load_idx);
1209 else
1210 load = target_load(i, load_idx);
1212 avg_load += load;
1215 /* Adjust by relative CPU power of the group */
1216 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
1218 if (local_group) {
1219 this_load = avg_load;
1220 this = group;
1221 } else if (avg_load < min_load) {
1222 min_load = avg_load;
1223 idlest = group;
1225 nextgroup:
1226 group = group->next;
1227 } while (group != sd->groups);
1229 if (!idlest || 100*this_load < imbalance*min_load)
1230 return NULL;
1231 return idlest;
1234 /*
1235 * find_idlest_queue - find the idlest runqueue among the cpus in group.
1236 */
1237 static int
1238 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1240 cpumask_t tmp;
1241 unsigned long load, min_load = ULONG_MAX;
1242 int idlest = -1;
1243 int i;
1245 /* Traverse only the allowed CPUs */
1246 cpus_and(tmp, group->cpumask, p->cpus_allowed);
1248 for_each_cpu_mask(i, tmp) {
1249 load = weighted_cpuload(i);
1251 if (load < min_load || (load == min_load && i == this_cpu)) {
1252 min_load = load;
1253 idlest = i;
1257 return idlest;
1260 /*
1261 * sched_balance_self: balance the current task (running on cpu) in domains
1262 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1263 * SD_BALANCE_EXEC.
1265 * Balance, ie. select the least loaded group.
1267 * Returns the target CPU number, or the same CPU if no balancing is needed.
1269 * preempt must be disabled.
1270 */
1271 static int sched_balance_self(int cpu, int flag)
1273 struct task_struct *t = current;
1274 struct sched_domain *tmp, *sd = NULL;
1276 for_each_domain(cpu, tmp) {
1277 /*
1278 * If power savings logic is enabled for a domain, stop there.
1279 */
1280 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1281 break;
1282 if (tmp->flags & flag)
1283 sd = tmp;
1286 while (sd) {
1287 cpumask_t span;
1288 struct sched_group *group;
1289 int new_cpu;
1290 int weight;
1292 span = sd->span;
1293 group = find_idlest_group(sd, t, cpu);
1294 if (!group)
1295 goto nextlevel;
1297 new_cpu = find_idlest_cpu(group, t, cpu);
1298 if (new_cpu == -1 || new_cpu == cpu)
1299 goto nextlevel;
1301 /* Now try balancing at a lower domain level */
1302 cpu = new_cpu;
1303 nextlevel:
1304 sd = NULL;
1305 weight = cpus_weight(span);
1306 for_each_domain(cpu, tmp) {
1307 if (weight <= cpus_weight(tmp->span))
1308 break;
1309 if (tmp->flags & flag)
1310 sd = tmp;
1312 /* while loop will break here if sd == NULL */
1315 return cpu;
1318 #endif /* CONFIG_SMP */
1320 /*
1321 * wake_idle() will wake a task on an idle cpu if task->cpu is
1322 * not idle and an idle cpu is available. The span of cpus to
1323 * search starts with cpus closest then further out as needed,
1324 * so we always favor a closer, idle cpu.
1326 * Returns the CPU we should wake onto.
1327 */
1328 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1329 static int wake_idle(int cpu, struct task_struct *p)
1331 cpumask_t tmp;
1332 struct sched_domain *sd;
1333 int i;
1335 if (idle_cpu(cpu))
1336 return cpu;
1338 for_each_domain(cpu, sd) {
1339 if (sd->flags & SD_WAKE_IDLE) {
1340 cpus_and(tmp, sd->span, p->cpus_allowed);
1341 for_each_cpu_mask(i, tmp) {
1342 if (idle_cpu(i))
1343 return i;
1346 else
1347 break;
1349 return cpu;
1351 #else
1352 static inline int wake_idle(int cpu, struct task_struct *p)
1354 return cpu;
1356 #endif
1358 /***
1359 * try_to_wake_up - wake up a thread
1360 * @p: the to-be-woken-up thread
1361 * @state: the mask of task states that can be woken
1362 * @sync: do a synchronous wakeup?
1364 * Put it on the run-queue if it's not already there. The "current"
1365 * thread is always on the run-queue (except when the actual
1366 * re-schedule is in progress), and as such you're allowed to do
1367 * the simpler "current->state = TASK_RUNNING" to mark yourself
1368 * runnable without the overhead of this.
1370 * returns failure only if the task is already active.
1371 */
1372 static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
1374 int cpu, this_cpu, success = 0;
1375 unsigned long flags;
1376 long old_state;
1377 struct rq *rq;
1378 #ifdef CONFIG_SMP
1379 struct sched_domain *sd, *this_sd = NULL;
1380 unsigned long load, this_load;
1381 int new_cpu;
1382 #endif
1384 rq = task_rq_lock(p, &flags);
1385 old_state = p->state;
1386 if (!(old_state & state))
1387 goto out;
1389 if (p->array)
1390 goto out_running;
1392 cpu = task_cpu(p);
1393 this_cpu = smp_processor_id();
1395 #ifdef CONFIG_SMP
1396 if (unlikely(task_running(rq, p)))
1397 goto out_activate;
1399 new_cpu = cpu;
1401 schedstat_inc(rq, ttwu_cnt);
1402 if (cpu == this_cpu) {
1403 schedstat_inc(rq, ttwu_local);
1404 goto out_set_cpu;
1407 for_each_domain(this_cpu, sd) {
1408 if (cpu_isset(cpu, sd->span)) {
1409 schedstat_inc(sd, ttwu_wake_remote);
1410 this_sd = sd;
1411 break;
1415 if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1416 goto out_set_cpu;
1418 /*
1419 * Check for affine wakeup and passive balancing possibilities.
1420 */
1421 if (this_sd) {
1422 int idx = this_sd->wake_idx;
1423 unsigned int imbalance;
1425 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1427 load = source_load(cpu, idx);
1428 this_load = target_load(this_cpu, idx);
1430 new_cpu = this_cpu; /* Wake to this CPU if we can */
1432 if (this_sd->flags & SD_WAKE_AFFINE) {
1433 unsigned long tl = this_load;
1434 unsigned long tl_per_task = cpu_avg_load_per_task(this_cpu);
1436 /*
1437 * If sync wakeup then subtract the (maximum possible)
1438 * effect of the currently running task from the load
1439 * of the current CPU:
1440 */
1441 if (sync)
1442 tl -= current->load_weight;
1444 if ((tl <= load &&
1445 tl + target_load(cpu, idx) <= tl_per_task) ||
1446 100*(tl + p->load_weight) <= imbalance*load) {
1447 /*
1448 * This domain has SD_WAKE_AFFINE and
1449 * p is cache cold in this domain, and
1450 * there is no bad imbalance.
1451 */
1452 schedstat_inc(this_sd, ttwu_move_affine);
1453 goto out_set_cpu;
1457 /*
1458 * Start passive balancing when half the imbalance_pct
1459 * limit is reached.
1460 */
1461 if (this_sd->flags & SD_WAKE_BALANCE) {
1462 if (imbalance*this_load <= 100*load) {
1463 schedstat_inc(this_sd, ttwu_move_balance);
1464 goto out_set_cpu;
1469 new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
1470 out_set_cpu:
1471 new_cpu = wake_idle(new_cpu, p);
1472 if (new_cpu != cpu) {
1473 set_task_cpu(p, new_cpu);
1474 task_rq_unlock(rq, &flags);
1475 /* might preempt at this point */
1476 rq = task_rq_lock(p, &flags);
1477 old_state = p->state;
1478 if (!(old_state & state))
1479 goto out;
1480 if (p->array)
1481 goto out_running;
1483 this_cpu = smp_processor_id();
1484 cpu = task_cpu(p);
1487 out_activate:
1488 #endif /* CONFIG_SMP */
1489 if (old_state == TASK_UNINTERRUPTIBLE) {
1490 rq->nr_uninterruptible--;
1491 /*
1492 * Tasks on involuntary sleep don't earn
1493 * sleep_avg beyond just interactive state.
1494 */
1495 p->sleep_type = SLEEP_NONINTERACTIVE;
1496 } else
1498 /*
1499 * Tasks that have marked their sleep as noninteractive get
1500 * woken up with their sleep average not weighted in an
1501 * interactive way.
1502 */
1503 if (old_state & TASK_NONINTERACTIVE)
1504 p->sleep_type = SLEEP_NONINTERACTIVE;
1507 activate_task(p, rq, cpu == this_cpu);
1508 /*
1509 * Sync wakeups (i.e. those types of wakeups where the waker
1510 * has indicated that it will leave the CPU in short order)
1511 * don't trigger a preemption, if the woken up task will run on
1512 * this cpu. (in this case the 'I will reschedule' promise of
1513 * the waker guarantees that the freshly woken up task is going
1514 * to be considered on this CPU.)
1515 */
1516 if (!sync || cpu != this_cpu) {
1517 if (TASK_PREEMPTS_CURR(p, rq))
1518 resched_task(rq->curr);
1520 success = 1;
1522 out_running:
1523 p->state = TASK_RUNNING;
1524 out:
1525 task_rq_unlock(rq, &flags);
1527 return success;
1530 int fastcall wake_up_process(struct task_struct *p)
1532 return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1533 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1535 EXPORT_SYMBOL(wake_up_process);
1537 int fastcall wake_up_state(struct task_struct *p, unsigned int state)
1539 return try_to_wake_up(p, state, 0);
1542 /*
1543 * Perform scheduler related setup for a newly forked process p.
1544 * p is forked by current.
1545 */
1546 void fastcall sched_fork(struct task_struct *p, int clone_flags)
1548 int cpu = get_cpu();
1550 #ifdef CONFIG_SMP
1551 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1552 #endif
1553 set_task_cpu(p, cpu);
1555 /*
1556 * We mark the process as running here, but have not actually
1557 * inserted it onto the runqueue yet. This guarantees that
1558 * nobody will actually run it, and a signal or other external
1559 * event cannot wake it up and insert it on the runqueue either.
1560 */
1561 p->state = TASK_RUNNING;
1563 /*
1564 * Make sure we do not leak PI boosting priority to the child:
1565 */
1566 p->prio = current->normal_prio;
1568 INIT_LIST_HEAD(&p->run_list);
1569 p->array = NULL;
1570 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1571 if (unlikely(sched_info_on()))
1572 memset(&p->sched_info, 0, sizeof(p->sched_info));
1573 #endif
1574 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1575 p->oncpu = 0;
1576 #endif
1577 #ifdef CONFIG_PREEMPT
1578 /* Want to start with kernel preemption disabled. */
1579 task_thread_info(p)->preempt_count = 1;
1580 #endif
1581 /*
1582 * Share the timeslice between parent and child, thus the
1583 * total amount of pending timeslices in the system doesn't change,
1584 * resulting in more scheduling fairness.
1585 */
1586 local_irq_disable();
1587 p->time_slice = (current->time_slice + 1) >> 1;
1588 /*
1589 * The remainder of the first timeslice might be recovered by
1590 * the parent if the child exits early enough.
1591 */
1592 p->first_time_slice = 1;
1593 current->time_slice >>= 1;
1594 p->timestamp = sched_clock();
1595 if (unlikely(!current->time_slice)) {
1596 /*
1597 * This case is rare, it happens when the parent has only
1598 * a single jiffy left from its timeslice. Taking the
1599 * runqueue lock is not a problem.
1600 */
1601 current->time_slice = 1;
1602 scheduler_tick();
1604 local_irq_enable();
1605 put_cpu();
1608 /*
1609 * wake_up_new_task - wake up a newly created task for the first time.
1611 * This function will do some initial scheduler statistics housekeeping
1612 * that must be done for every newly created context, then puts the task
1613 * on the runqueue and wakes it.
1614 */
1615 void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
1617 struct rq *rq, *this_rq;
1618 unsigned long flags;
1619 int this_cpu, cpu;
1621 rq = task_rq_lock(p, &flags);
1622 BUG_ON(p->state != TASK_RUNNING);
1623 this_cpu = smp_processor_id();
1624 cpu = task_cpu(p);
1626 /*
1627 * We decrease the sleep average of forking parents
1628 * and children as well, to keep max-interactive tasks
1629 * from forking tasks that are max-interactive. The parent
1630 * (current) is done further down, under its lock.
1631 */
1632 p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
1633 CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1635 p->prio = effective_prio(p);
1637 if (likely(cpu == this_cpu)) {
1638 if (!(clone_flags & CLONE_VM)) {
1639 /*
1640 * The VM isn't cloned, so we're in a good position to
1641 * do child-runs-first in anticipation of an exec. This
1642 * usually avoids a lot of COW overhead.
1643 */
1644 if (unlikely(!current->array))
1645 __activate_task(p, rq);
1646 else {
1647 p->prio = current->prio;
1648 p->normal_prio = current->normal_prio;
1649 list_add_tail(&p->run_list, &current->run_list);
1650 p->array = current->array;
1651 p->array->nr_active++;
1652 inc_nr_running(p, rq);
1654 set_need_resched();
1655 } else
1656 /* Run child last */
1657 __activate_task(p, rq);
1658 /*
1659 * We skip the following code due to cpu == this_cpu
1661 * task_rq_unlock(rq, &flags);
1662 * this_rq = task_rq_lock(current, &flags);
1663 */
1664 this_rq = rq;
1665 } else {
1666 this_rq = cpu_rq(this_cpu);
1668 /*
1669 * Not the local CPU - must adjust timestamp. This should
1670 * get optimised away in the !CONFIG_SMP case.
1671 */
1672 p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
1673 + rq->timestamp_last_tick;
1674 __activate_task(p, rq);
1675 if (TASK_PREEMPTS_CURR(p, rq))
1676 resched_task(rq->curr);
1678 /*
1679 * Parent and child are on different CPUs, now get the
1680 * parent runqueue to update the parent's ->sleep_avg:
1681 */
1682 task_rq_unlock(rq, &flags);
1683 this_rq = task_rq_lock(current, &flags);
1685 current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
1686 PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1687 task_rq_unlock(this_rq, &flags);
1690 /*
1691 * Potentially available exiting-child timeslices are
1692 * retrieved here - this way the parent does not get
1693 * penalized for creating too many threads.
1695 * (this cannot be used to 'generate' timeslices
1696 * artificially, because any timeslice recovered here
1697 * was given away by the parent in the first place.)
1698 */
1699 void fastcall sched_exit(struct task_struct *p)
1701 unsigned long flags;
1702 struct rq *rq;
1704 /*
1705 * If the child was a (relative-) CPU hog then decrease
1706 * the sleep_avg of the parent as well.
1707 */
1708 rq = task_rq_lock(p->parent, &flags);
1709 if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) {
1710 p->parent->time_slice += p->time_slice;
1711 if (unlikely(p->parent->time_slice > task_timeslice(p)))
1712 p->parent->time_slice = task_timeslice(p);
1714 if (p->sleep_avg < p->parent->sleep_avg)
1715 p->parent->sleep_avg = p->parent->sleep_avg /
1716 (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
1717 (EXIT_WEIGHT + 1);
1718 task_rq_unlock(rq, &flags);
1721 /**
1722 * prepare_task_switch - prepare to switch tasks
1723 * @rq: the runqueue preparing to switch
1724 * @next: the task we are going to switch to.
1726 * This is called with the rq lock held and interrupts off. It must
1727 * be paired with a subsequent finish_task_switch after the context
1728 * switch.
1730 * prepare_task_switch sets up locking and calls architecture specific
1731 * hooks.
1732 */
1733 static inline void prepare_task_switch(struct rq *rq, struct task_struct *next)
1735 prepare_lock_switch(rq, next);
1736 prepare_arch_switch(next);
1739 /**
1740 * finish_task_switch - clean up after a task-switch
1741 * @rq: runqueue associated with task-switch
1742 * @prev: the thread we just switched away from.
1744 * finish_task_switch must be called after the context switch, paired
1745 * with a prepare_task_switch call before the context switch.
1746 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1747 * and do any other architecture-specific cleanup actions.
1749 * Note that we may have delayed dropping an mm in context_switch(). If
1750 * so, we finish that here outside of the runqueue lock. (Doing it
1751 * with the lock held can cause deadlocks; see schedule() for
1752 * details.)
1753 */
1754 static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
1755 __releases(rq->lock)
1757 struct mm_struct *mm = rq->prev_mm;
1758 unsigned long prev_task_flags;
1760 rq->prev_mm = NULL;
1762 /*
1763 * A task struct has one reference for the use as "current".
1764 * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1765 * calls schedule one last time. The schedule call will never return,
1766 * and the scheduled task must drop that reference.
1767 * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1768 * still held, otherwise prev could be scheduled on another cpu, die
1769 * there before we look at prev->state, and then the reference would
1770 * be dropped twice.
1771 * Manfred Spraul <manfred@colorfullife.com>
1772 */
1773 prev_task_flags = prev->flags;
1774 finish_arch_switch(prev);
1775 finish_lock_switch(rq, prev);
1776 if (mm)
1777 mmdrop(mm);
1778 if (unlikely(prev_task_flags & PF_DEAD)) {
1779 /*
1780 * Remove function-return probe instances associated with this
1781 * task and put them back on the free list.
1782 */
1783 kprobe_flush_task(prev);
1784 put_task_struct(prev);
1788 /**
1789 * schedule_tail - first thing a freshly forked thread must call.
1790 * @prev: the thread we just switched away from.
1791 */
1792 asmlinkage void schedule_tail(struct task_struct *prev)
1793 __releases(rq->lock)
1795 struct rq *rq = this_rq();
1797 finish_task_switch(rq, prev);
1798 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1799 /* In this case, finish_task_switch does not reenable preemption */
1800 preempt_enable();
1801 #endif
1802 if (current->set_child_tid)
1803 put_user(current->pid, current->set_child_tid);
1806 /*
1807 * context_switch - switch to the new MM and the new
1808 * thread's register state.
1809 */
1810 static inline struct task_struct *
1811 context_switch(struct rq *rq, struct task_struct *prev,
1812 struct task_struct *next)
1814 struct mm_struct *mm = next->mm;
1815 struct mm_struct *oldmm = prev->active_mm;
1817 if (unlikely(!mm)) {
1818 next->active_mm = oldmm;
1819 atomic_inc(&oldmm->mm_count);
1820 enter_lazy_tlb(oldmm, next);
1821 } else
1822 switch_mm(oldmm, mm, next);
1824 if (unlikely(!prev->mm)) {
1825 prev->active_mm = NULL;
1826 WARN_ON(rq->prev_mm);
1827 rq->prev_mm = oldmm;
1829 /*
1830 * Since the runqueue lock will be released by the next
1831 * task (which is an invalid locking op but in the case
1832 * of the scheduler it's an obvious special-case), so we
1833 * do an early lockdep release here:
1834 */
1835 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1836 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
1837 #endif
1839 /* Here we just switch the register state and the stack. */
1840 switch_to(prev, next, prev);
1842 return prev;
1845 /*
1846 * nr_running, nr_uninterruptible and nr_context_switches:
1848 * externally visible scheduler statistics: current number of runnable
1849 * threads, current number of uninterruptible-sleeping threads, total
1850 * number of context switches performed since bootup.
1851 */
1852 unsigned long nr_running(void)
1854 unsigned long i, sum = 0;
1856 for_each_online_cpu(i)
1857 sum += cpu_rq(i)->nr_running;
1859 return sum;
1862 unsigned long nr_uninterruptible(void)
1864 unsigned long i, sum = 0;
1866 for_each_possible_cpu(i)
1867 sum += cpu_rq(i)->nr_uninterruptible;
1869 /*
1870 * Since we read the counters lockless, it might be slightly
1871 * inaccurate. Do not allow it to go below zero though:
1872 */
1873 if (unlikely((long)sum < 0))
1874 sum = 0;
1876 return sum;
1879 unsigned long long nr_context_switches(void)
1881 int i;
1882 unsigned long long sum = 0;
1884 for_each_possible_cpu(i)
1885 sum += cpu_rq(i)->nr_switches;
1887 return sum;
1890 unsigned long nr_iowait(void)
1892 unsigned long i, sum = 0;
1894 for_each_possible_cpu(i)
1895 sum += atomic_read(&cpu_rq(i)->nr_iowait);
1897 return sum;
1900 unsigned long nr_active(void)
1902 unsigned long i, running = 0, uninterruptible = 0;
1904 for_each_online_cpu(i) {
1905 running += cpu_rq(i)->nr_running;
1906 uninterruptible += cpu_rq(i)->nr_uninterruptible;
1909 if (unlikely((long)uninterruptible < 0))
1910 uninterruptible = 0;
1912 return running + uninterruptible;
1915 #ifdef CONFIG_SMP
1917 /*
1918 * Is this task likely cache-hot:
1919 */
1920 static inline int
1921 task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
1923 return (long long)(now - p->last_ran) < (long long)sd->cache_hot_time;
1926 /*
1927 * double_rq_lock - safely lock two runqueues
1929 * Note this does not disable interrupts like task_rq_lock,
1930 * you need to do so manually before calling.
1931 */
1932 static void double_rq_lock(struct rq *rq1, struct rq *rq2)
1933 __acquires(rq1->lock)
1934 __acquires(rq2->lock)
1936 if (rq1 == rq2) {
1937 spin_lock(&rq1->lock);
1938 __acquire(rq2->lock); /* Fake it out ;) */
1939 } else {
1940 if (rq1 < rq2) {
1941 spin_lock(&rq1->lock);
1942 spin_lock(&rq2->lock);
1943 } else {
1944 spin_lock(&rq2->lock);
1945 spin_lock(&rq1->lock);
1950 /*
1951 * double_rq_unlock - safely unlock two runqueues
1953 * Note this does not restore interrupts like task_rq_unlock,
1954 * you need to do so manually after calling.
1955 */
1956 static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
1957 __releases(rq1->lock)
1958 __releases(rq2->lock)
1960 spin_unlock(&rq1->lock);
1961 if (rq1 != rq2)
1962 spin_unlock(&rq2->lock);
1963 else
1964 __release(rq2->lock);
1967 /*
1968 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1969 */
1970 static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
1971 __releases(this_rq->lock)
1972 __acquires(busiest->lock)
1973 __acquires(this_rq->lock)
1975 if (unlikely(!spin_trylock(&busiest->lock))) {
1976 if (busiest < this_rq) {
1977 spin_unlock(&this_rq->lock);
1978 spin_lock(&busiest->lock);
1979 spin_lock(&this_rq->lock);
1980 } else
1981 spin_lock(&busiest->lock);
1985 /*
1986 * If dest_cpu is allowed for this process, migrate the task to it.
1987 * This is accomplished by forcing the cpu_allowed mask to only
1988 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
1989 * the cpu_allowed mask is restored.
1990 */
1991 static void sched_migrate_task(struct task_struct *p, int dest_cpu)
1993 struct migration_req req;
1994 unsigned long flags;
1995 struct rq *rq;
1997 rq = task_rq_lock(p, &flags);
1998 if (!cpu_isset(dest_cpu, p->cpus_allowed)
1999 || unlikely(cpu_is_offline(dest_cpu)))
2000 goto out;
2002 /* force the process onto the specified CPU */
2003 if (migrate_task(p, dest_cpu, &req)) {
2004 /* Need to wait for migration thread (might exit: take ref). */
2005 struct task_struct *mt = rq->migration_thread;
2007 get_task_struct(mt);
2008 task_rq_unlock(rq, &flags);
2009 wake_up_process(mt);
2010 put_task_struct(mt);
2011 wait_for_completion(&req.done);
2013 return;
2015 out:
2016 task_rq_unlock(rq, &flags);
2019 /*
2020 * sched_exec - execve() is a valuable balancing opportunity, because at
2021 * this point the task has the smallest effective memory and cache footprint.
2022 */
2023 void sched_exec(void)
2025 int new_cpu, this_cpu = get_cpu();
2026 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
2027 put_cpu();
2028 if (new_cpu != this_cpu)
2029 sched_migrate_task(current, new_cpu);
2032 /*
2033 * pull_task - move a task from a remote runqueue to the local runqueue.
2034 * Both runqueues must be locked.
2035 */
2036 static void pull_task(struct rq *src_rq, struct prio_array *src_array,
2037 struct task_struct *p, struct rq *this_rq,
2038 struct prio_array *this_array, int this_cpu)
2040 dequeue_task(p, src_array);
2041 dec_nr_running(p, src_rq);
2042 set_task_cpu(p, this_cpu);
2043 inc_nr_running(p, this_rq);
2044 enqueue_task(p, this_array);
2045 p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
2046 + this_rq->timestamp_last_tick;
2047 /*
2048 * Note that idle threads have a prio of MAX_PRIO, for this test
2049 * to be always true for them.
2050 */
2051 if (TASK_PREEMPTS_CURR(p, this_rq))
2052 resched_task(this_rq->curr);
2055 /*
2056 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2057 */
2058 static
2059 int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
2060 struct sched_domain *sd, enum idle_type idle,
2061 int *all_pinned)
2063 /*
2064 * We do not migrate tasks that are:
2065 * 1) running (obviously), or
2066 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2067 * 3) are cache-hot on their current CPU.
2068 */
2069 if (!cpu_isset(this_cpu, p->cpus_allowed))
2070 return 0;
2071 *all_pinned = 0;
2073 if (task_running(rq, p))
2074 return 0;
2076 /*
2077 * Aggressive migration if:
2078 * 1) task is cache cold, or
2079 * 2) too many balance attempts have failed.
2080 */
2082 if (sd->nr_balance_failed > sd->cache_nice_tries)
2083 return 1;
2085 if (task_hot(p, rq->timestamp_last_tick, sd))
2086 return 0;
2087 return 1;
2090 #define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
2092 /*
2093 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2094 * load from busiest to this_rq, as part of a balancing operation within
2095 * "domain". Returns the number of tasks moved.
2097 * Called with both runqueues locked.
2098 */
2099 static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2100 unsigned long max_nr_move, unsigned long max_load_move,
2101 struct sched_domain *sd, enum idle_type idle,
2102 int *all_pinned)
2104 int idx, pulled = 0, pinned = 0, this_best_prio, best_prio,
2105 best_prio_seen, skip_for_load;
2106 struct prio_array *array, *dst_array;
2107 struct list_head *head, *curr;
2108 struct task_struct *tmp;
2109 long rem_load_move;
2111 if (max_nr_move == 0 || max_load_move == 0)
2112 goto out;
2114 rem_load_move = max_load_move;
2115 pinned = 1;
2116 this_best_prio = rq_best_prio(this_rq);
2117 best_prio = rq_best_prio(busiest);
2118 /*
2119 * Enable handling of the case where there is more than one task
2120 * with the best priority. If the current running task is one
2121 * of those with prio==best_prio we know it won't be moved
2122 * and therefore it's safe to override the skip (based on load) of
2123 * any task we find with that prio.
2124 */
2125 best_prio_seen = best_prio == busiest->curr->prio;
2127 /*
2128 * We first consider expired tasks. Those will likely not be
2129 * executed in the near future, and they are most likely to
2130 * be cache-cold, thus switching CPUs has the least effect
2131 * on them.
2132 */
2133 if (busiest->expired->nr_active) {
2134 array = busiest->expired;
2135 dst_array = this_rq->expired;
2136 } else {
2137 array = busiest->active;
2138 dst_array = this_rq->active;
2141 new_array:
2142 /* Start searching at priority 0: */
2143 idx = 0;
2144 skip_bitmap:
2145 if (!idx)
2146 idx = sched_find_first_bit(array->bitmap);
2147 else
2148 idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
2149 if (idx >= MAX_PRIO) {
2150 if (array == busiest->expired && busiest->active->nr_active) {
2151 array = busiest->active;
2152 dst_array = this_rq->active;
2153 goto new_array;
2155 goto out;
2158 head = array->queue + idx;
2159 curr = head->prev;
2160 skip_queue:
2161 tmp = list_entry(curr, struct task_struct, run_list);
2163 curr = curr->prev;
2165 /*
2166 * To help distribute high priority tasks accross CPUs we don't
2167 * skip a task if it will be the highest priority task (i.e. smallest
2168 * prio value) on its new queue regardless of its load weight
2169 */
2170 skip_for_load = tmp->load_weight > rem_load_move;
2171 if (skip_for_load && idx < this_best_prio)
2172 skip_for_load = !best_prio_seen && idx == best_prio;
2173 if (skip_for_load ||
2174 !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
2176 best_prio_seen |= idx == best_prio;
2177 if (curr != head)
2178 goto skip_queue;
2179 idx++;
2180 goto skip_bitmap;
2183 #ifdef CONFIG_SCHEDSTATS
2184 if (task_hot(tmp, busiest->timestamp_last_tick, sd))
2185 schedstat_inc(sd, lb_hot_gained[idle]);
2186 #endif
2188 pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
2189 pulled++;
2190 rem_load_move -= tmp->load_weight;
2192 /*
2193 * We only want to steal up to the prescribed number of tasks
2194 * and the prescribed amount of weighted load.
2195 */
2196 if (pulled < max_nr_move && rem_load_move > 0) {
2197 if (idx < this_best_prio)
2198 this_best_prio = idx;
2199 if (curr != head)
2200 goto skip_queue;
2201 idx++;
2202 goto skip_bitmap;
2204 out:
2205 /*
2206 * Right now, this is the only place pull_task() is called,
2207 * so we can safely collect pull_task() stats here rather than
2208 * inside pull_task().
2209 */
2210 schedstat_add(sd, lb_gained[idle], pulled);
2212 if (all_pinned)
2213 *all_pinned = pinned;
2214 return pulled;
2217 /*
2218 * find_busiest_group finds and returns the busiest CPU group within the
2219 * domain. It calculates and returns the amount of weighted load which
2220 * should be moved to restore balance via the imbalance parameter.
2221 */
2222 static struct sched_group *
2223 find_busiest_group(struct sched_domain *sd, int this_cpu,
2224 unsigned long *imbalance, enum idle_type idle, int *sd_idle,
2225 cpumask_t *cpus)
2227 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
2228 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
2229 unsigned long max_pull;
2230 unsigned long busiest_load_per_task, busiest_nr_running;
2231 unsigned long this_load_per_task, this_nr_running;
2232 int load_idx;
2233 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2234 int power_savings_balance = 1;
2235 unsigned long leader_nr_running = 0, min_load_per_task = 0;
2236 unsigned long min_nr_running = ULONG_MAX;
2237 struct sched_group *group_min = NULL, *group_leader = NULL;
2238 #endif
2240 max_load = this_load = total_load = total_pwr = 0;
2241 busiest_load_per_task = busiest_nr_running = 0;
2242 this_load_per_task = this_nr_running = 0;
2243 if (idle == NOT_IDLE)
2244 load_idx = sd->busy_idx;
2245 else if (idle == NEWLY_IDLE)
2246 load_idx = sd->newidle_idx;
2247 else
2248 load_idx = sd->idle_idx;
2250 do {
2251 unsigned long load, group_capacity;
2252 int local_group;
2253 int i;
2254 unsigned long sum_nr_running, sum_weighted_load;
2256 local_group = cpu_isset(this_cpu, group->cpumask);
2258 /* Tally up the load of all CPUs in the group */
2259 sum_weighted_load = sum_nr_running = avg_load = 0;
2261 for_each_cpu_mask(i, group->cpumask) {
2262 struct rq *rq;
2264 if (!cpu_isset(i, *cpus))
2265 continue;
2267 rq = cpu_rq(i);
2269 if (*sd_idle && !idle_cpu(i))
2270 *sd_idle = 0;
2272 /* Bias balancing toward cpus of our domain */
2273 if (local_group)
2274 load = target_load(i, load_idx);
2275 else
2276 load = source_load(i, load_idx);
2278 avg_load += load;
2279 sum_nr_running += rq->nr_running;
2280 sum_weighted_load += rq->raw_weighted_load;
2283 total_load += avg_load;
2284 total_pwr += group->cpu_power;
2286 /* Adjust by relative CPU power of the group */
2287 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
2289 group_capacity = group->cpu_power / SCHED_LOAD_SCALE;
2291 if (local_group) {
2292 this_load = avg_load;
2293 this = group;
2294 this_nr_running = sum_nr_running;
2295 this_load_per_task = sum_weighted_load;
2296 } else if (avg_load > max_load &&
2297 sum_nr_running > group_capacity) {
2298 max_load = avg_load;
2299 busiest = group;
2300 busiest_nr_running = sum_nr_running;
2301 busiest_load_per_task = sum_weighted_load;
2304 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2305 /*
2306 * Busy processors will not participate in power savings
2307 * balance.
2308 */
2309 if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2310 goto group_next;
2312 /*
2313 * If the local group is idle or completely loaded
2314 * no need to do power savings balance at this domain
2315 */
2316 if (local_group && (this_nr_running >= group_capacity ||
2317 !this_nr_running))
2318 power_savings_balance = 0;
2320 /*
2321 * If a group is already running at full capacity or idle,
2322 * don't include that group in power savings calculations
2323 */
2324 if (!power_savings_balance || sum_nr_running >= group_capacity
2325 || !sum_nr_running)
2326 goto group_next;
2328 /*
2329 * Calculate the group which has the least non-idle load.
2330 * This is the group from where we need to pick up the load
2331 * for saving power
2332 */
2333 if ((sum_nr_running < min_nr_running) ||
2334 (sum_nr_running == min_nr_running &&
2335 first_cpu(group->cpumask) <
2336 first_cpu(group_min->cpumask))) {
2337 group_min = group;
2338 min_nr_running = sum_nr_running;
2339 min_load_per_task = sum_weighted_load /
2340 sum_nr_running;
2343 /*
2344 * Calculate the group which is almost near its
2345 * capacity but still has some space to pick up some load
2346 * from other group and save more power
2347 */
2348 if (sum_nr_running <= group_capacity - 1) {
2349 if (sum_nr_running > leader_nr_running ||
2350 (sum_nr_running == leader_nr_running &&
2351 first_cpu(group->cpumask) >
2352 first_cpu(group_leader->cpumask))) {
2353 group_leader = group;
2354 leader_nr_running = sum_nr_running;
2357 group_next:
2358 #endif
2359 group = group->next;
2360 } while (group != sd->groups);
2362 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
2363 goto out_balanced;
2365 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
2367 if (this_load >= avg_load ||
2368 100*max_load <= sd->imbalance_pct*this_load)
2369 goto out_balanced;
2371 busiest_load_per_task /= busiest_nr_running;
2372 /*
2373 * We're trying to get all the cpus to the average_load, so we don't
2374 * want to push ourselves above the average load, nor do we wish to
2375 * reduce the max loaded cpu below the average load, as either of these
2376 * actions would just result in more rebalancing later, and ping-pong
2377 * tasks around. Thus we look for the minimum possible imbalance.
2378 * Negative imbalances (*we* are more loaded than anyone else) will
2379 * be counted as no imbalance for these purposes -- we can't fix that
2380 * by pulling tasks to us. Be careful of negative numbers as they'll
2381 * appear as very large values with unsigned longs.
2382 */
2383 if (max_load <= busiest_load_per_task)
2384 goto out_balanced;
2386 /*
2387 * In the presence of smp nice balancing, certain scenarios can have
2388 * max load less than avg load(as we skip the groups at or below
2389 * its cpu_power, while calculating max_load..)
2390 */
2391 if (max_load < avg_load) {
2392 *imbalance = 0;
2393 goto small_imbalance;
2396 /* Don't want to pull so many tasks that a group would go idle */
2397 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
2399 /* How much load to actually move to equalise the imbalance */
2400 *imbalance = min(max_pull * busiest->cpu_power,
2401 (avg_load - this_load) * this->cpu_power)
2402 / SCHED_LOAD_SCALE;
2404 /*
2405 * if *imbalance is less than the average load per runnable task
2406 * there is no gaurantee that any tasks will be moved so we'll have
2407 * a think about bumping its value to force at least one task to be
2408 * moved
2409 */
2410 if (*imbalance < busiest_load_per_task) {
2411 unsigned long tmp, pwr_now, pwr_move;
2412 unsigned int imbn;
2414 small_imbalance:
2415 pwr_move = pwr_now = 0;
2416 imbn = 2;
2417 if (this_nr_running) {
2418 this_load_per_task /= this_nr_running;
2419 if (busiest_load_per_task > this_load_per_task)
2420 imbn = 1;
2421 } else
2422 this_load_per_task = SCHED_LOAD_SCALE;
2424 if (max_load - this_load >= busiest_load_per_task * imbn) {
2425 *imbalance = busiest_load_per_task;
2426 return busiest;
2429 /*
2430 * OK, we don't have enough imbalance to justify moving tasks,
2431 * however we may be able to increase total CPU power used by
2432 * moving them.
2433 */
2435 pwr_now += busiest->cpu_power *
2436 min(busiest_load_per_task, max_load);
2437 pwr_now += this->cpu_power *
2438 min(this_load_per_task, this_load);
2439 pwr_now /= SCHED_LOAD_SCALE;
2441 /* Amount of load we'd subtract */
2442 tmp = busiest_load_per_task*SCHED_LOAD_SCALE/busiest->cpu_power;
2443 if (max_load > tmp)
2444 pwr_move += busiest->cpu_power *
2445 min(busiest_load_per_task, max_load - tmp);
2447 /* Amount of load we'd add */
2448 if (max_load*busiest->cpu_power <
2449 busiest_load_per_task*SCHED_LOAD_SCALE)
2450 tmp = max_load*busiest->cpu_power/this->cpu_power;
2451 else
2452 tmp = busiest_load_per_task*SCHED_LOAD_SCALE/this->cpu_power;
2453 pwr_move += this->cpu_power*min(this_load_per_task, this_load + tmp);
2454 pwr_move /= SCHED_LOAD_SCALE;
2456 /* Move if we gain throughput */
2457 if (pwr_move <= pwr_now)
2458 goto out_balanced;
2460 *imbalance = busiest_load_per_task;
2463 return busiest;
2465 out_balanced:
2466 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2467 if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2468 goto ret;
2470 if (this == group_leader && group_leader != group_min) {
2471 *imbalance = min_load_per_task;
2472 return group_min;
2474 ret:
2475 #endif
2476 *imbalance = 0;
2477 return NULL;
2480 /*
2481 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2482 */
2483 static struct rq *
2484 find_busiest_queue(struct sched_group *group, enum idle_type idle,
2485 unsigned long imbalance, cpumask_t *cpus)
2487 struct rq *busiest = NULL, *rq;
2488 unsigned long max_load = 0;
2489 int i;
2491 for_each_cpu_mask(i, group->cpumask) {
2493 if (!cpu_isset(i, *cpus))
2494 continue;
2496 rq = cpu_rq(i);
2498 if (rq->nr_running == 1 && rq->raw_weighted_load > imbalance)
2499 continue;
2501 if (rq->raw_weighted_load > max_load) {
2502 max_load = rq->raw_weighted_load;
2503 busiest = rq;
2507 return busiest;
2510 /*
2511 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2512 * so long as it is large enough.
2513 */
2514 #define MAX_PINNED_INTERVAL 512
2516 static inline unsigned long minus_1_or_zero(unsigned long n)
2518 return n > 0 ? n - 1 : 0;
2521 /*
2522 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2523 * tasks if there is an imbalance.
2525 * Called with this_rq unlocked.
2526 */
2527 static int load_balance(int this_cpu, struct rq *this_rq,
2528 struct sched_domain *sd, enum idle_type idle)
2530 int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
2531 struct sched_group *group;
2532 unsigned long imbalance;
2533 struct rq *busiest;
2534 cpumask_t cpus = CPU_MASK_ALL;
2536 if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
2537 !sched_smt_power_savings)
2538 sd_idle = 1;
2540 schedstat_inc(sd, lb_cnt[idle]);
2542 redo:
2543 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
2544 &cpus);
2545 if (!group) {
2546 schedstat_inc(sd, lb_nobusyg[idle]);
2547 goto out_balanced;
2550 busiest = find_busiest_queue(group, idle, imbalance, &cpus);
2551 if (!busiest) {
2552 schedstat_inc(sd, lb_nobusyq[idle]);
2553 goto out_balanced;
2556 BUG_ON(busiest == this_rq);
2558 schedstat_add(sd, lb_imbalance[idle], imbalance);
2560 nr_moved = 0;
2561 if (busiest->nr_running > 1) {
2562 /*
2563 * Attempt to move tasks. If find_busiest_group has found
2564 * an imbalance but busiest->nr_running <= 1, the group is
2565 * still unbalanced. nr_moved simply stays zero, so it is
2566 * correctly treated as an imbalance.
2567 */
2568 double_rq_lock(this_rq, busiest);
2569 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2570 minus_1_or_zero(busiest->nr_running),
2571 imbalance, sd, idle, &all_pinned);
2572 double_rq_unlock(this_rq, busiest);
2574 /* All tasks on this runqueue were pinned by CPU affinity */
2575 if (unlikely(all_pinned)) {
2576 cpu_clear(cpu_of(busiest), cpus);
2577 if (!cpus_empty(cpus))
2578 goto redo;
2579 goto out_balanced;
2583 if (!nr_moved) {
2584 schedstat_inc(sd, lb_failed[idle]);
2585 sd->nr_balance_failed++;
2587 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
2589 spin_lock(&busiest->lock);
2591 /* don't kick the migration_thread, if the curr
2592 * task on busiest cpu can't be moved to this_cpu
2593 */
2594 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
2595 spin_unlock(&busiest->lock);
2596 all_pinned = 1;
2597 goto out_one_pinned;
2600 if (!busiest->active_balance) {
2601 busiest->active_balance = 1;
2602 busiest->push_cpu = this_cpu;
2603 active_balance = 1;
2605 spin_unlock(&busiest->lock);
2606 if (active_balance)
2607 wake_up_process(busiest->migration_thread);
2609 /*
2610 * We've kicked active balancing, reset the failure
2611 * counter.
2612 */
2613 sd->nr_balance_failed = sd->cache_nice_tries+1;
2615 } else
2616 sd->nr_balance_failed = 0;
2618 if (likely(!active_balance)) {
2619 /* We were unbalanced, so reset the balancing interval */
2620 sd->balance_interval = sd->min_interval;
2621 } else {
2622 /*
2623 * If we've begun active balancing, start to back off. This
2624 * case may not be covered by the all_pinned logic if there
2625 * is only 1 task on the busy runqueue (because we don't call
2626 * move_tasks).
2627 */
2628 if (sd->balance_interval < sd->max_interval)
2629 sd->balance_interval *= 2;
2632 if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2633 !sched_smt_power_savings)
2634 return -1;
2635 return nr_moved;
2637 out_balanced:
2638 schedstat_inc(sd, lb_balanced[idle]);
2640 sd->nr_balance_failed = 0;
2642 out_one_pinned:
2643 /* tune up the balancing interval */
2644 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
2645 (sd->balance_interval < sd->max_interval))
2646 sd->balance_interval *= 2;
2648 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2649 !sched_smt_power_savings)
2650 return -1;
2651 return 0;
2654 /*
2655 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2656 * tasks if there is an imbalance.
2658 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2659 * this_rq is locked.
2660 */
2661 static int
2662 load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
2664 struct sched_group *group;
2665 struct rq *busiest = NULL;
2666 unsigned long imbalance;
2667 int nr_moved = 0;
2668 int sd_idle = 0;
2669 cpumask_t cpus = CPU_MASK_ALL;
2671 if (sd->flags & SD_SHARE_CPUPOWER && !sched_smt_power_savings)
2672 sd_idle = 1;
2674 schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
2675 redo:
2676 group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE,
2677 &sd_idle, &cpus);
2678 if (!group) {
2679 schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
2680 goto out_balanced;
2683 busiest = find_busiest_queue(group, NEWLY_IDLE, imbalance,
2684 &cpus);
2685 if (!busiest) {
2686 schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
2687 goto out_balanced;
2690 BUG_ON(busiest == this_rq);
2692 schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
2694 nr_moved = 0;
2695 if (busiest->nr_running > 1) {
2696 /* Attempt to move tasks */
2697 double_lock_balance(this_rq, busiest);
2698 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2699 minus_1_or_zero(busiest->nr_running),
2700 imbalance, sd, NEWLY_IDLE, NULL);
2701 spin_unlock(&busiest->lock);
2703 if (!nr_moved) {
2704 cpu_clear(cpu_of(busiest), cpus);
2705 if (!cpus_empty(cpus))
2706 goto redo;
2710 if (!nr_moved) {
2711 schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
2712 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER)
2713 return -1;
2714 } else
2715 sd->nr_balance_failed = 0;
2717 return nr_moved;
2719 out_balanced:
2720 schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
2721 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2722 !sched_smt_power_savings)
2723 return -1;
2724 sd->nr_balance_failed = 0;
2726 return 0;
2729 /*
2730 * idle_balance is called by schedule() if this_cpu is about to become
2731 * idle. Attempts to pull tasks from other CPUs.
2732 */
2733 static void idle_balance(int this_cpu, struct rq *this_rq)
2735 struct sched_domain *sd;
2737 for_each_domain(this_cpu, sd) {
2738 if (sd->flags & SD_BALANCE_NEWIDLE) {
2739 /* If we've pulled tasks over stop searching: */
2740 if (load_balance_newidle(this_cpu, this_rq, sd))
2741 break;
2746 /*
2747 * active_load_balance is run by migration threads. It pushes running tasks
2748 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2749 * running on each physical CPU where possible, and avoids physical /
2750 * logical imbalances.
2752 * Called with busiest_rq locked.
2753 */
2754 static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
2756 int target_cpu = busiest_rq->push_cpu;
2757 struct sched_domain *sd;
2758 struct rq *target_rq;
2760 /* Is there any task to move? */
2761 if (busiest_rq->nr_running <= 1)
2762 return;
2764 target_rq = cpu_rq(target_cpu);
2766 /*
2767 * This condition is "impossible", if it occurs
2768 * we need to fix it. Originally reported by
2769 * Bjorn Helgaas on a 128-cpu setup.
2770 */
2771 BUG_ON(busiest_rq == target_rq);
2773 /* move a task from busiest_rq to target_rq */
2774 double_lock_balance(busiest_rq, target_rq);
2776 /* Search for an sd spanning us and the target CPU. */
2777 for_each_domain(target_cpu, sd) {
2778 if ((sd->flags & SD_LOAD_BALANCE) &&
2779 cpu_isset(busiest_cpu, sd->span))
2780 break;
2783 if (likely(sd)) {
2784 schedstat_inc(sd, alb_cnt);
2786 if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
2787 RTPRIO_TO_LOAD_WEIGHT(100), sd, SCHED_IDLE,
2788 NULL))
2789 schedstat_inc(sd, alb_pushed);
2790 else
2791 schedstat_inc(sd, alb_failed);
2793 spin_unlock(&target_rq->lock);
2796 /*
2797 * rebalance_tick will get called every timer tick, on every CPU.
2799 * It checks each scheduling domain to see if it is due to be balanced,
2800 * and initiates a balancing operation if so.
2802 * Balancing parameters are set up in arch_init_sched_domains.
2803 */
2805 /* Don't have all balancing operations going off at once: */
2806 static inline unsigned long cpu_offset(int cpu)
2808 return jiffies + cpu * HZ / NR_CPUS;
2811 static void
2812 rebalance_tick(int this_cpu, struct rq *this_rq, enum idle_type idle)
2814 unsigned long this_load, interval, j = cpu_offset(this_cpu);
2815 struct sched_domain *sd;
2816 int i, scale;
2818 this_load = this_rq->raw_weighted_load;
2820 /* Update our load: */
2821 for (i = 0, scale = 1; i < 3; i++, scale <<= 1) {
2822 unsigned long old_load, new_load;
2824 old_load = this_rq->cpu_load[i];
2825 new_load = this_load;
2826 /*
2827 * Round up the averaging division if load is increasing. This
2828 * prevents us from getting stuck on 9 if the load is 10, for
2829 * example.
2830 */
2831 if (new_load > old_load)
2832 new_load += scale-1;
2833 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale;
2836 for_each_domain(this_cpu, sd) {
2837 if (!(sd->flags & SD_LOAD_BALANCE))
2838 continue;
2840 interval = sd->balance_interval;
2841 if (idle != SCHED_IDLE)
2842 interval *= sd->busy_factor;
2844 /* scale ms to jiffies */
2845 interval = msecs_to_jiffies(interval);
2846 if (unlikely(!interval))
2847 interval = 1;
2849 if (j - sd->last_balance >= interval) {
2850 if (load_balance(this_cpu, this_rq, sd, idle)) {
2851 /*
2852 * We've pulled tasks over so either we're no
2853 * longer idle, or one of our SMT siblings is
2854 * not idle.
2855 */
2856 idle = NOT_IDLE;
2858 sd->last_balance += interval;
2862 #else
2863 /*
2864 * on UP we do not need to balance between CPUs:
2865 */
2866 static inline void rebalance_tick(int cpu, struct rq *rq, enum idle_type idle)
2869 static inline void idle_balance(int cpu, struct rq *rq)
2872 #endif
2874 static inline int wake_priority_sleeper(struct rq *rq)
2876 int ret = 0;
2878 #ifdef CONFIG_SCHED_SMT
2879 spin_lock(&rq->lock);
2880 /*
2881 * If an SMT sibling task has been put to sleep for priority
2882 * reasons reschedule the idle task to see if it can now run.
2883 */
2884 if (rq->nr_running) {
2885 resched_task(rq->idle);
2886 ret = 1;
2888 spin_unlock(&rq->lock);
2889 #endif
2890 return ret;
2893 DEFINE_PER_CPU(struct kernel_stat, kstat);
2895 EXPORT_PER_CPU_SYMBOL(kstat);
2897 /*
2898 * This is called on clock ticks and on context switches.
2899 * Bank in p->sched_time the ns elapsed since the last tick or switch.
2900 */
2901 static inline void
2902 update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now)
2904 p->sched_time += now - max(p->timestamp, rq->timestamp_last_tick);
2907 /*
2908 * Return current->sched_time plus any more ns on the sched_clock
2909 * that have not yet been banked.
2910 */
2911 unsigned long long current_sched_time(const struct task_struct *p)
2913 unsigned long long ns;
2914 unsigned long flags;
2916 local_irq_save(flags);
2917 ns = max(p->timestamp, task_rq(p)->timestamp_last_tick);
2918 ns = p->sched_time + sched_clock() - ns;
2919 local_irq_restore(flags);
2921 return ns;
2924 /*
2925 * We place interactive tasks back into the active array, if possible.
2927 * To guarantee that this does not starve expired tasks we ignore the
2928 * interactivity of a task if the first expired task had to wait more
2929 * than a 'reasonable' amount of time. This deadline timeout is
2930 * load-dependent, as the frequency of array switched decreases with
2931 * increasing number of running tasks. We also ignore the interactivity
2932 * if a better static_prio task has expired:
2933 */
2934 static inline int expired_starving(struct rq *rq)
2936 if (rq->curr->static_prio > rq->best_expired_prio)
2937 return 1;
2938 if (!STARVATION_LIMIT || !rq->expired_timestamp)
2939 return 0;
2940 if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
2941 return 1;
2942 return 0;
2945 /*
2946 * Account user cpu time to a process.
2947 * @p: the process that the cpu time gets accounted to
2948 * @hardirq_offset: the offset to subtract from hardirq_count()
2949 * @cputime: the cpu time spent in user space since the last update
2950 */
2951 void account_user_time(struct task_struct *p, cputime_t cputime)
2953 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2954 cputime64_t tmp;
2956 p->utime = cputime_add(p->utime, cputime);
2958 /* Add user time to cpustat. */
2959 tmp = cputime_to_cputime64(cputime);
2960 if (TASK_NICE(p) > 0)
2961 cpustat->nice = cputime64_add(cpustat->nice, tmp);
2962 else
2963 cpustat->user = cputime64_add(cpustat->user, tmp);
2966 /*
2967 * Account system cpu time to a process.
2968 * @p: the process that the cpu time gets accounted to
2969 * @hardirq_offset: the offset to subtract from hardirq_count()
2970 * @cputime: the cpu time spent in kernel space since the last update
2971 */
2972 void account_system_time(struct task_struct *p, int hardirq_offset,
2973 cputime_t cputime)
2975 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2976 struct rq *rq = this_rq();
2977 cputime64_t tmp;
2979 p->stime = cputime_add(p->stime, cputime);
2981 /* Add system time to cpustat. */
2982 tmp = cputime_to_cputime64(cputime);
2983 if (hardirq_count() - hardirq_offset)
2984 cpustat->irq = cputime64_add(cpustat->irq, tmp);
2985 else if (softirq_count())
2986 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
2987 else if (p != rq->idle)
2988 cpustat->system = cputime64_add(cpustat->system, tmp);
2989 else if (atomic_read(&rq->nr_iowait) > 0)
2990 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
2991 else
2992 cpustat->idle = cputime64_add(cpustat->idle, tmp);
2993 /* Account for system time used */
2994 acct_update_integrals(p);
2997 /*
2998 * Account for involuntary wait time.
2999 * @p: the process from which the cpu time has been stolen
3000 * @steal: the cpu time spent in involuntary wait
3001 */
3002 void account_steal_time(struct task_struct *p, cputime_t steal)
3004 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3005 cputime64_t tmp = cputime_to_cputime64(steal);
3006 struct rq *rq = this_rq();
3008 if (p == rq->idle) {
3009 p->stime = cputime_add(p->stime, steal);
3010 if (atomic_read(&rq->nr_iowait) > 0)
3011 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3012 else
3013 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3014 } else
3015 cpustat->steal = cputime64_add(cpustat->steal, tmp);
3018 /*
3019 * This function gets called by the timer code, with HZ frequency.
3020 * We call it with interrupts disabled.
3022 * It also gets called by the fork code, when changing the parent's
3023 * timeslices.
3024 */
3025 void scheduler_tick(void)
3027 unsigned long long now = sched_clock();
3028 struct task_struct *p = current;
3029 int cpu = smp_processor_id();
3030 struct rq *rq = cpu_rq(cpu);
3032 update_cpu_clock(p, rq, now);
3034 rq->timestamp_last_tick = now;
3036 if (p == rq->idle) {
3037 if (wake_priority_sleeper(rq))
3038 goto out;
3039 rebalance_tick(cpu, rq, SCHED_IDLE);
3040 return;
3043 /* Task might have expired already, but not scheduled off yet */
3044 if (p->array != rq->active) {
3045 set_tsk_need_resched(p);
3046 goto out;
3048 spin_lock(&rq->lock);
3049 /*
3050 * The task was running during this tick - update the
3051 * time slice counter. Note: we do not update a thread's
3052 * priority until it either goes to sleep or uses up its
3053 * timeslice. This makes it possible for interactive tasks
3054 * to use up their timeslices at their highest priority levels.
3055 */
3056 if (rt_task(p)) {
3057 /*
3058 * RR tasks need a special form of timeslice management.
3059 * FIFO tasks have no timeslices.
3060 */
3061 if ((p->policy == SCHED_RR) && !--p->time_slice) {
3062 p->time_slice = task_timeslice(p);
3063 p->first_time_slice = 0;
3064 set_tsk_need_resched(p);
3066 /* put it at the end of the queue: */
3067 requeue_task(p, rq->active);
3069 goto out_unlock;
3071 if (!--p->time_slice) {
3072 dequeue_task(p, rq->active);
3073 set_tsk_need_resched(p);
3074 p->prio = effective_prio(p);
3075 p->time_slice = task_timeslice(p);
3076 p->first_time_slice = 0;
3078 if (!rq->expired_timestamp)
3079 rq->expired_timestamp = jiffies;
3080 if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
3081 enqueue_task(p, rq->expired);
3082 if (p->static_prio < rq->best_expired_prio)
3083 rq->best_expired_prio = p->static_prio;
3084 } else
3085 enqueue_task(p, rq->active);
3086 } else {
3087 /*
3088 * Prevent a too long timeslice allowing a task to monopolize
3089 * the CPU. We do this by splitting up the timeslice into
3090 * smaller pieces.
3092 * Note: this does not mean the task's timeslices expire or
3093 * get lost in any way, they just might be preempted by
3094 * another task of equal priority. (one with higher
3095 * priority would have preempted this task already.) We
3096 * requeue this task to the end of the list on this priority
3097 * level, which is in essence a round-robin of tasks with
3098 * equal priority.
3100 * This only applies to tasks in the interactive
3101 * delta range with at least TIMESLICE_GRANULARITY to requeue.
3102 */
3103 if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
3104 p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
3105 (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
3106 (p->array == rq->active)) {
3108 requeue_task(p, rq->active);
3109 set_tsk_need_resched(p);
3112 out_unlock:
3113 spin_unlock(&rq->lock);
3114 out:
3115 rebalance_tick(cpu, rq, NOT_IDLE);
3118 #ifdef CONFIG_SCHED_SMT
3119 static inline void wakeup_busy_runqueue(struct rq *rq)
3121 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
3122 if (rq->curr == rq->idle && rq->nr_running)
3123 resched_task(rq->idle);
3126 /*
3127 * Called with interrupt disabled and this_rq's runqueue locked.
3128 */
3129 static void wake_sleeping_dependent(int this_cpu)
3131 struct sched_domain *tmp, *sd = NULL;
3132 int i;
3134 for_each_domain(this_cpu, tmp) {
3135 if (tmp->flags & SD_SHARE_CPUPOWER) {
3136 sd = tmp;
3137 break;
3141 if (!sd)
3142 return;
3144 for_each_cpu_mask(i, sd->span) {
3145 struct rq *smt_rq = cpu_rq(i);
3147 if (i == this_cpu)
3148 continue;
3149 if (unlikely(!spin_trylock(&smt_rq->lock)))
3150 continue;
3152 wakeup_busy_runqueue(smt_rq);
3153 spin_unlock(&smt_rq->lock);
3157 /*
3158 * number of 'lost' timeslices this task wont be able to fully
3159 * utilize, if another task runs on a sibling. This models the
3160 * slowdown effect of other tasks running on siblings:
3161 */
3162 static inline unsigned long
3163 smt_slice(struct task_struct *p, struct sched_domain *sd)
3165 return p->time_slice * (100 - sd->per_cpu_gain) / 100;
3168 /*
3169 * To minimise lock contention and not have to drop this_rq's runlock we only
3170 * trylock the sibling runqueues and bypass those runqueues if we fail to
3171 * acquire their lock. As we only trylock the normal locking order does not
3172 * need to be obeyed.
3173 */
3174 static int
3175 dependent_sleeper(int this_cpu, struct rq *this_rq, struct task_struct *p)
3177 struct sched_domain *tmp, *sd = NULL;
3178 int ret = 0, i;
3180 /* kernel/rt threads do not participate in dependent sleeping */
3181 if (!p->mm || rt_task(p))
3182 return 0;
3184 for_each_domain(this_cpu, tmp) {
3185 if (tmp->flags & SD_SHARE_CPUPOWER) {
3186 sd = tmp;
3187 break;
3191 if (!sd)
3192 return 0;
3194 for_each_cpu_mask(i, sd->span) {
3195 struct task_struct *smt_curr;
3196 struct rq *smt_rq;
3198 if (i == this_cpu)
3199 continue;
3201 smt_rq = cpu_rq(i);
3202 if (unlikely(!spin_trylock(&smt_rq->lock)))
3203 continue;
3205 smt_curr = smt_rq->curr;
3207 if (!smt_curr->mm)
3208 goto unlock;
3210 /*
3211 * If a user task with lower static priority than the
3212 * running task on the SMT sibling is trying to schedule,
3213 * delay it till there is proportionately less timeslice
3214 * left of the sibling task to prevent a lower priority
3215 * task from using an unfair proportion of the
3216 * physical cpu's resources. -ck
3217 */
3218 if (rt_task(smt_curr)) {
3219 /*
3220 * With real time tasks we run non-rt tasks only
3221 * per_cpu_gain% of the time.
3222 */
3223 if ((jiffies % DEF_TIMESLICE) >
3224 (sd->per_cpu_gain * DEF_TIMESLICE / 100))
3225 ret = 1;
3226 } else {
3227 if (smt_curr->static_prio < p->static_prio &&
3228 !TASK_PREEMPTS_CURR(p, smt_rq) &&
3229 smt_slice(smt_curr, sd) > task_timeslice(p))
3230 ret = 1;
3232 unlock:
3233 spin_unlock(&smt_rq->lock);
3235 return ret;
3237 #else
3238 static inline void wake_sleeping_dependent(int this_cpu)
3241 static inline int
3242 dependent_sleeper(int this_cpu, struct rq *this_rq, struct task_struct *p)
3244 return 0;
3246 #endif
3248 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3250 void fastcall add_preempt_count(int val)
3252 /*
3253 * Underflow?
3254 */
3255 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3256 return;
3257 preempt_count() += val;
3258 /*
3259 * Spinlock count overflowing soon?
3260 */
3261 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10);
3263 EXPORT_SYMBOL(add_preempt_count);
3265 void fastcall sub_preempt_count(int val)
3267 /*
3268 * Underflow?
3269 */
3270 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3271 return;
3272 /*
3273 * Is the spinlock portion underflowing?
3274 */
3275 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3276 !(preempt_count() & PREEMPT_MASK)))
3277 return;
3279 preempt_count() -= val;
3281 EXPORT_SYMBOL(sub_preempt_count);
3283 #endif
3285 static inline int interactive_sleep(enum sleep_type sleep_type)
3287 return (sleep_type == SLEEP_INTERACTIVE ||
3288 sleep_type == SLEEP_INTERRUPTED);
3291 /*
3292 * schedule() is the main scheduler function.
3293 */
3294 asmlinkage void __sched schedule(void)
3296 struct task_struct *prev, *next;
3297 struct prio_array *array;
3298 struct list_head *queue;
3299 unsigned long long now;
3300 unsigned long run_time;
3301 int cpu, idx, new_prio;
3302 long *switch_count;
3303 struct rq *rq;
3305 /*
3306 * Test if we are atomic. Since do_exit() needs to call into
3307 * schedule() atomically, we ignore that path for now.
3308 * Otherwise, whine if we are scheduling when we should not be.
3309 */
3310 if (unlikely(in_atomic() && !current->exit_state)) {
3311 printk(KERN_ERR "BUG: scheduling while atomic: "
3312 "%s/0x%08x/%d\n",
3313 current->comm, preempt_count(), current->pid);
3314 dump_stack();
3316 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3318 need_resched:
3319 preempt_disable();
3320 prev = current;
3321 release_kernel_lock(prev);
3322 need_resched_nonpreemptible:
3323 rq = this_rq();
3325 /*
3326 * The idle thread is not allowed to schedule!
3327 * Remove this check after it has been exercised a bit.
3328 */
3329 if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
3330 printk(KERN_ERR "bad: scheduling from the idle thread!\n");
3331 dump_stack();
3334 schedstat_inc(rq, sched_cnt);
3335 now = sched_clock();
3336 if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
3337 run_time = now - prev->timestamp;
3338 if (unlikely((long long)(now - prev->timestamp) < 0))
3339 run_time = 0;
3340 } else
3341 run_time = NS_MAX_SLEEP_AVG;
3343 /*
3344 * Tasks charged proportionately less run_time at high sleep_avg to
3345 * delay them losing their interactive status
3346 */
3347 run_time /= (CURRENT_BONUS(prev) ? : 1);
3349 spin_lock_irq(&rq->lock);
3351 if (unlikely(prev->flags & PF_DEAD))
3352 prev->state = EXIT_DEAD;
3354 switch_count = &prev->nivcsw;
3355 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3356 switch_count = &prev->nvcsw;
3357 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
3358 unlikely(signal_pending(prev))))
3359 prev->state = TASK_RUNNING;
3360 else {
3361 if (prev->state == TASK_UNINTERRUPTIBLE)
3362 rq->nr_uninterruptible++;
3363 deactivate_task(prev, rq);
3367 cpu = smp_processor_id();
3368 if (unlikely(!rq->nr_running)) {
3369 idle_balance(cpu, rq);
3370 if (!rq->nr_running) {
3371 next = rq->idle;
3372 rq->expired_timestamp = 0;
3373 wake_sleeping_dependent(cpu);
3374 goto switch_tasks;
3378 array = rq->active;
3379 if (unlikely(!array->nr_active)) {
3380 /*
3381 * Switch the active and expired arrays.
3382 */
3383 schedstat_inc(rq, sched_switch);
3384 rq->active = rq->expired;
3385 rq->expired = array;
3386 array = rq->active;
3387 rq->expired_timestamp = 0;
3388 rq->best_expired_prio = MAX_PRIO;
3391 idx = sched_find_first_bit(array->bitmap);
3392 queue = array->queue + idx;
3393 next = list_entry(queue->next, struct task_struct, run_list);
3395 if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
3396 unsigned long long delta = now - next->timestamp;
3397 if (unlikely((long long)(now - next->timestamp) < 0))
3398 delta = 0;
3400 if (next->sleep_type == SLEEP_INTERACTIVE)
3401 delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
3403 array = next->array;
3404 new_prio = recalc_task_prio(next, next->timestamp + delta);
3406 if (unlikely(next->prio != new_prio)) {
3407 dequeue_task(next, array);
3408 next->prio = new_prio;
3409 enqueue_task(next, array);
3412 next->sleep_type = SLEEP_NORMAL;
3413 if (dependent_sleeper(cpu, rq, next))
3414 next = rq->idle;
3415 switch_tasks:
3416 if (next == rq->idle)
3417 schedstat_inc(rq, sched_goidle);
3418 prefetch(next);
3419 prefetch_stack(next);
3420 clear_tsk_need_resched(prev);
3421 rcu_qsctr_inc(task_cpu(prev));
3423 update_cpu_clock(prev, rq, now);
3425 prev->sleep_avg -= run_time;
3426 if ((long)prev->sleep_avg <= 0)
3427 prev->sleep_avg = 0;
3428 prev->timestamp = prev->last_ran = now;
3430 sched_info_switch(prev, next);
3431 if (likely(prev != next)) {
3432 next->timestamp = now;
3433 rq->nr_switches++;
3434 rq->curr = next;
3435 ++*switch_count;
3437 prepare_task_switch(rq, next);
3438 prev = context_switch(rq, prev, next);
3439 barrier();
3440 /*
3441 * this_rq must be evaluated again because prev may have moved
3442 * CPUs since it called schedule(), thus the 'rq' on its stack
3443 * frame will be invalid.
3444 */
3445 finish_task_switch(this_rq(), prev);
3446 } else
3447 spin_unlock_irq(&rq->lock);
3449 prev = current;
3450 if (unlikely(reacquire_kernel_lock(prev) < 0))
3451 goto need_resched_nonpreemptible;
3452 preempt_enable_no_resched();
3453 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3454 goto need_resched;
3456 EXPORT_SYMBOL(schedule);
3458 #ifdef CONFIG_PREEMPT
3459 /*
3460 * this is the entry point to schedule() from in-kernel preemption
3461 * off of preempt_enable. Kernel preemptions off return from interrupt
3462 * occur there and call schedule directly.
3463 */
3464 asmlinkage void __sched preempt_schedule(void)
3466 struct thread_info *ti = current_thread_info();
3467 #ifdef CONFIG_PREEMPT_BKL
3468 struct task_struct *task = current;
3469 int saved_lock_depth;
3470 #endif
3471 /*
3472 * If there is a non-zero preempt_count or interrupts are disabled,
3473 * we do not want to preempt the current task. Just return..
3474 */
3475 if (unlikely(ti->preempt_count || irqs_disabled()))
3476 return;
3478 need_resched:
3479 add_preempt_count(PREEMPT_ACTIVE);
3480 /*
3481 * We keep the big kernel semaphore locked, but we
3482 * clear ->lock_depth so that schedule() doesnt
3483 * auto-release the semaphore:
3484 */
3485 #ifdef CONFIG_PREEMPT_BKL
3486 saved_lock_depth = task->lock_depth;
3487 task->lock_depth = -1;
3488 #endif
3489 schedule();
3490 #ifdef CONFIG_PREEMPT_BKL
3491 task->lock_depth = saved_lock_depth;
3492 #endif
3493 sub_preempt_count(PREEMPT_ACTIVE);
3495 /* we could miss a preemption opportunity between schedule and now */
3496 barrier();
3497 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3498 goto need_resched;
3500 EXPORT_SYMBOL(preempt_schedule);
3502 /*
3503 * this is the entry point to schedule() from kernel preemption
3504 * off of irq context.
3505 * Note, that this is called and return with irqs disabled. This will
3506 * protect us against recursive calling from irq.
3507 */
3508 asmlinkage void __sched preempt_schedule_irq(void)
3510 struct thread_info *ti = current_thread_info();
3511 #ifdef CONFIG_PREEMPT_BKL
3512 struct task_struct *task = current;
3513 int saved_lock_depth;
3514 #endif
3515 /* Catch callers which need to be fixed */
3516 BUG_ON(ti->preempt_count || !irqs_disabled());
3518 need_resched:
3519 add_preempt_count(PREEMPT_ACTIVE);
3520 /*
3521 * We keep the big kernel semaphore locked, but we
3522 * clear ->lock_depth so that schedule() doesnt
3523 * auto-release the semaphore:
3524 */
3525 #ifdef CONFIG_PREEMPT_BKL
3526 saved_lock_depth = task->lock_depth;
3527 task->lock_depth = -1;
3528 #endif
3529 local_irq_enable();
3530 schedule();
3531 local_irq_disable();
3532 #ifdef CONFIG_PREEMPT_BKL
3533 task->lock_depth = saved_lock_depth;
3534 #endif
3535 sub_preempt_count(PREEMPT_ACTIVE);
3537 /* we could miss a preemption opportunity between schedule and now */
3538 barrier();
3539 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3540 goto need_resched;
3543 #endif /* CONFIG_PREEMPT */
3545 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
3546 void *key)
3548 return try_to_wake_up(curr->private, mode, sync);
3550 EXPORT_SYMBOL(default_wake_function);
3552 /*
3553 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3554 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3555 * number) then we wake all the non-exclusive tasks and one exclusive task.
3557 * There are circumstances in which we can try to wake a task which has already
3558 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3559 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3560 */
3561 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3562 int nr_exclusive, int sync, void *key)
3564 struct list_head *tmp, *next;
3566 list_for_each_safe(tmp, next, &q->task_list) {
3567 wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
3568 unsigned flags = curr->flags;
3570 if (curr->func(curr, mode, sync, key) &&
3571 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
3572 break;
3576 /**
3577 * __wake_up - wake up threads blocked on a waitqueue.
3578 * @q: the waitqueue
3579 * @mode: which threads
3580 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3581 * @key: is directly passed to the wakeup function
3582 */
3583 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
3584 int nr_exclusive, void *key)
3586 unsigned long flags;
3588 spin_lock_irqsave(&q->lock, flags);
3589 __wake_up_common(q, mode, nr_exclusive, 0, key);
3590 spin_unlock_irqrestore(&q->lock, flags);
3592 EXPORT_SYMBOL(__wake_up);
3594 /*
3595 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3596 */
3597 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3599 __wake_up_common(q, mode, 1, 0, NULL);
3602 /**
3603 * __wake_up_sync - wake up threads blocked on a waitqueue.
3604 * @q: the waitqueue
3605 * @mode: which threads
3606 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3608 * The sync wakeup differs that the waker knows that it will schedule
3609 * away soon, so while the target thread will be woken up, it will not
3610 * be migrated to another CPU - ie. the two threads are 'synchronized'
3611 * with each other. This can prevent needless bouncing between CPUs.
3613 * On UP it can prevent extra preemption.
3614 */
3615 void fastcall
3616 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3618 unsigned long flags;
3619 int sync = 1;
3621 if (unlikely(!q))
3622 return;
3624 if (unlikely(!nr_exclusive))
3625 sync = 0;
3627 spin_lock_irqsave(&q->lock, flags);
3628 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
3629 spin_unlock_irqrestore(&q->lock, flags);
3631 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
3633 void fastcall complete(struct completion *x)
3635 unsigned long flags;
3637 spin_lock_irqsave(&x->wait.lock, flags);
3638 x->done++;
3639 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3640 1, 0, NULL);
3641 spin_unlock_irqrestore(&x->wait.lock, flags);
3643 EXPORT_SYMBOL(complete);
3645 void fastcall complete_all(struct completion *x)
3647 unsigned long flags;
3649 spin_lock_irqsave(&x->wait.lock, flags);
3650 x->done += UINT_MAX/2;
3651 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3652 0, 0, NULL);
3653 spin_unlock_irqrestore(&x->wait.lock, flags);
3655 EXPORT_SYMBOL(complete_all);
3657 void fastcall __sched wait_for_completion(struct completion *x)
3659 might_sleep();
3661 spin_lock_irq(&x->wait.lock);
3662 if (!x->done) {
3663 DECLARE_WAITQUEUE(wait, current);
3665 wait.flags |= WQ_FLAG_EXCLUSIVE;
3666 __add_wait_queue_tail(&x->wait, &wait);
3667 do {
3668 __set_current_state(TASK_UNINTERRUPTIBLE);
3669 spin_unlock_irq(&x->wait.lock);
3670 schedule();
3671 spin_lock_irq(&x->wait.lock);
3672 } while (!x->done);
3673 __remove_wait_queue(&x->wait, &wait);
3675 x->done--;
3676 spin_unlock_irq(&x->wait.lock);
3678 EXPORT_SYMBOL(wait_for_completion);
3680 unsigned long fastcall __sched
3681 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3683 might_sleep();
3685 spin_lock_irq(&x->wait.lock);
3686 if (!x->done) {
3687 DECLARE_WAITQUEUE(wait, current);
3689 wait.flags |= WQ_FLAG_EXCLUSIVE;
3690 __add_wait_queue_tail(&x->wait, &wait);
3691 do {
3692 __set_current_state(TASK_UNINTERRUPTIBLE);
3693 spin_unlock_irq(&x->wait.lock);
3694 timeout = schedule_timeout(timeout);
3695 spin_lock_irq(&x->wait.lock);
3696 if (!timeout) {
3697 __remove_wait_queue(&x->wait, &wait);
3698 goto out;
3700 } while (!x->done);
3701 __remove_wait_queue(&x->wait, &wait);
3703 x->done--;
3704 out:
3705 spin_unlock_irq(&x->wait.lock);
3706 return timeout;
3708 EXPORT_SYMBOL(wait_for_completion_timeout);
3710 int fastcall __sched wait_for_completion_interruptible(struct completion *x)
3712 int ret = 0;
3714 might_sleep();
3716 spin_lock_irq(&x->wait.lock);
3717 if (!x->done) {
3718 DECLARE_WAITQUEUE(wait, current);
3720 wait.flags |= WQ_FLAG_EXCLUSIVE;
3721 __add_wait_queue_tail(&x->wait, &wait);
3722 do {
3723 if (signal_pending(current)) {
3724 ret = -ERESTARTSYS;
3725 __remove_wait_queue(&x->wait, &wait);
3726 goto out;
3728 __set_current_state(TASK_INTERRUPTIBLE);
3729 spin_unlock_irq(&x->wait.lock);
3730 schedule();
3731 spin_lock_irq(&x->wait.lock);
3732 } while (!x->done);
3733 __remove_wait_queue(&x->wait, &wait);
3735 x->done--;
3736 out:
3737 spin_unlock_irq(&x->wait.lock);
3739 return ret;
3741 EXPORT_SYMBOL(wait_for_completion_interruptible);
3743 unsigned long fastcall __sched
3744 wait_for_completion_interruptible_timeout(struct completion *x,
3745 unsigned long timeout)
3747 might_sleep();
3749 spin_lock_irq(&x->wait.lock);
3750 if (!x->done) {
3751 DECLARE_WAITQUEUE(wait, current);
3753 wait.flags |= WQ_FLAG_EXCLUSIVE;
3754 __add_wait_queue_tail(&x->wait, &wait);
3755 do {
3756 if (signal_pending(current)) {
3757 timeout = -ERESTARTSYS;
3758 __remove_wait_queue(&x->wait, &wait);
3759 goto out;
3761 __set_current_state(TASK_INTERRUPTIBLE);
3762 spin_unlock_irq(&x->wait.lock);
3763 timeout = schedule_timeout(timeout);
3764 spin_lock_irq(&x->wait.lock);
3765 if (!timeout) {
3766 __remove_wait_queue(&x->wait, &wait);
3767 goto out;
3769 } while (!x->done);
3770 __remove_wait_queue(&x->wait, &wait);
3772 x->done--;
3773 out:
3774 spin_unlock_irq(&x->wait.lock);
3775 return timeout;
3777 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3780 #define SLEEP_ON_VAR \
3781 unsigned long flags; \
3782 wait_queue_t wait; \
3783 init_waitqueue_entry(&wait, current);
3785 #define SLEEP_ON_HEAD \
3786 spin_lock_irqsave(&q->lock,flags); \
3787 __add_wait_queue(q, &wait); \
3788 spin_unlock(&q->lock);
3790 #define SLEEP_ON_TAIL \
3791 spin_lock_irq(&q->lock); \
3792 __remove_wait_queue(q, &wait); \
3793 spin_unlock_irqrestore(&q->lock, flags);
3795 void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
3797 SLEEP_ON_VAR
3799 current->state = TASK_INTERRUPTIBLE;
3801 SLEEP_ON_HEAD
3802 schedule();
3803 SLEEP_ON_TAIL
3805 EXPORT_SYMBOL(interruptible_sleep_on);
3807 long fastcall __sched
3808 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3810 SLEEP_ON_VAR
3812 current->state = TASK_INTERRUPTIBLE;
3814 SLEEP_ON_HEAD
3815 timeout = schedule_timeout(timeout);
3816 SLEEP_ON_TAIL
3818 return timeout;
3820 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3822 void fastcall __sched sleep_on(wait_queue_head_t *q)
3824 SLEEP_ON_VAR
3826 current->state = TASK_UNINTERRUPTIBLE;
3828 SLEEP_ON_HEAD
3829 schedule();
3830 SLEEP_ON_TAIL
3832 EXPORT_SYMBOL(sleep_on);
3834 long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3836 SLEEP_ON_VAR
3838 current->state = TASK_UNINTERRUPTIBLE;
3840 SLEEP_ON_HEAD
3841 timeout = schedule_timeout(timeout);
3842 SLEEP_ON_TAIL
3844 return timeout;
3847 EXPORT_SYMBOL(sleep_on_timeout);
3849 #ifdef CONFIG_RT_MUTEXES
3851 /*
3852 * rt_mutex_setprio - set the current priority of a task
3853 * @p: task
3854 * @prio: prio value (kernel-internal form)
3856 * This function changes the 'effective' priority of a task. It does
3857 * not touch ->normal_prio like __setscheduler().
3859 * Used by the rt_mutex code to implement priority inheritance logic.
3860 */
3861 void rt_mutex_setprio(struct task_struct *p, int prio)
3863 struct prio_array *array;
3864 unsigned long flags;
3865 struct rq *rq;
3866 int oldprio;
3868 BUG_ON(prio < 0 || prio > MAX_PRIO);
3870 rq = task_rq_lock(p, &flags);
3872 oldprio = p->prio;
3873 array = p->array;
3874 if (array)
3875 dequeue_task(p, array);
3876 p->prio = prio;
3878 if (array) {
3879 /*
3880 * If changing to an RT priority then queue it
3881 * in the active array!
3882 */
3883 if (rt_task(p))
3884 array = rq->active;
3885 enqueue_task(p, array);
3886 /*
3887 * Reschedule if we are currently running on this runqueue and
3888 * our priority decreased, or if we are not currently running on
3889 * this runqueue and our priority is higher than the current's
3890 */
3891 if (task_running(rq, p)) {
3892 if (p->prio > oldprio)
3893 resched_task(rq->curr);
3894 } else if (TASK_PREEMPTS_CURR(p, rq))
3895 resched_task(rq->curr);
3897 task_rq_unlock(rq, &flags);
3900 #endif
3902 void set_user_nice(struct task_struct *p, long nice)
3904 struct prio_array *array;
3905 int old_prio, delta;
3906 unsigned long flags;
3907 struct rq *rq;
3909 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3910 return;
3911 /*
3912 * We have to be careful, if called from sys_setpriority(),
3913 * the task might be in the middle of scheduling on another CPU.
3914 */
3915 rq = task_rq_lock(p, &flags);
3916 /*
3917 * The RT priorities are set via sched_setscheduler(), but we still
3918 * allow the 'normal' nice value to be set - but as expected
3919 * it wont have any effect on scheduling until the task is
3920 * not SCHED_NORMAL/SCHED_BATCH:
3921 */
3922 if (has_rt_policy(p)) {
3923 p->static_prio = NICE_TO_PRIO(nice);
3924 goto out_unlock;
3926 array = p->array;
3927 if (array) {
3928 dequeue_task(p, array);
3929 dec_raw_weighted_load(rq, p);
3932 p->static_prio = NICE_TO_PRIO(nice);
3933 set_load_weight(p);
3934 old_prio = p->prio;
3935 p->prio = effective_prio(p);
3936 delta = p->prio - old_prio;
3938 if (array) {
3939 enqueue_task(p, array);
3940 inc_raw_weighted_load(rq, p);
3941 /*
3942 * If the task increased its priority or is running and
3943 * lowered its priority, then reschedule its CPU:
3944 */
3945 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3946 resched_task(rq->curr);
3948 out_unlock:
3949 task_rq_unlock(rq, &flags);
3951 EXPORT_SYMBOL(set_user_nice);
3953 /*
3954 * can_nice - check if a task can reduce its nice value
3955 * @p: task
3956 * @nice: nice value
3957 */
3958 int can_nice(const struct task_struct *p, const int nice)
3960 /* convert nice value [19,-20] to rlimit style value [1,40] */
3961 int nice_rlim = 20 - nice;
3963 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
3964 capable(CAP_SYS_NICE));
3967 #ifdef __ARCH_WANT_SYS_NICE
3969 /*
3970 * sys_nice - change the priority of the current process.
3971 * @increment: priority increment
3973 * sys_setpriority is a more generic, but much slower function that
3974 * does similar things.
3975 */
3976 asmlinkage long sys_nice(int increment)
3978 long nice, retval;
3980 /*
3981 * Setpriority might change our priority at the same moment.
3982 * We don't have to worry. Conceptually one call occurs first
3983 * and we have a single winner.
3984 */
3985 if (increment < -40)
3986 increment = -40;
3987 if (increment > 40)
3988 increment = 40;
3990 nice = PRIO_TO_NICE(current->static_prio) + increment;
3991 if (nice < -20)
3992 nice = -20;
3993 if (nice > 19)
3994 nice = 19;
3996 if (increment < 0 && !can_nice(current, nice))
3997 return -EPERM;
3999 retval = security_task_setnice(current, nice);
4000 if (retval)
4001 return retval;
4003 set_user_nice(current, nice);
4004 return 0;
4007 #endif
4009 /**
4010 * task_prio - return the priority value of a given task.
4011 * @p: the task in question.
4013 * This is the priority value as seen by users in /proc.
4014 * RT tasks are offset by -200. Normal tasks are centered
4015 * around 0, value goes from -16 to +15.
4016 */
4017 int task_prio(const struct task_struct *p)
4019 return p->prio - MAX_RT_PRIO;
4022 /**
4023 * task_nice - return the nice value of a given task.
4024 * @p: the task in question.
4025 */
4026 int task_nice(const struct task_struct *p)
4028 return TASK_NICE(p);
4030 EXPORT_SYMBOL_GPL(task_nice);
4032 /**
4033 * idle_cpu - is a given cpu idle currently?
4034 * @cpu: the processor in question.
4035 */
4036 int idle_cpu(int cpu)
4038 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4041 /**
4042 * idle_task - return the idle task for a given cpu.
4043 * @cpu: the processor in question.
4044 */
4045 struct task_struct *idle_task(int cpu)
4047 return cpu_rq(cpu)->idle;
4050 /**
4051 * find_process_by_pid - find a process with a matching PID value.
4052 * @pid: the pid in question.
4053 */
4054 static inline struct task_struct *find_process_by_pid(pid_t pid)
4056 return pid ? find_task_by_pid(pid) : current;
4059 /* Actually do priority change: must hold rq lock. */
4060 static void __setscheduler(struct task_struct *p, int policy, int prio)
4062 BUG_ON(p->array);
4064 p->policy = policy;
4065 p->rt_priority = prio;
4066 p->normal_prio = normal_prio(p);
4067 /* we are holding p->pi_lock already */
4068 p->prio = rt_mutex_getprio(p);
4069 /*
4070 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
4071 */
4072 if (policy == SCHED_BATCH)
4073 p->sleep_avg = 0;
4074 set_load_weight(p);
4077 /**
4078 * sched_setscheduler - change the scheduling policy and/or RT priority of
4079 * a thread.
4080 * @p: the task in question.
4081 * @policy: new policy.
4082 * @param: structure containing the new RT priority.
4083 */
4084 int sched_setscheduler(struct task_struct *p, int policy,
4085 struct sched_param *param)
4087 int retval, oldprio, oldpolicy = -1;
4088 struct prio_array *array;
4089 unsigned long flags;
4090 struct rq *rq;
4092 /* may grab non-irq protected spin_locks */
4093 BUG_ON(in_interrupt());
4094 recheck:
4095 /* double check policy once rq lock held */
4096 if (policy < 0)
4097 policy = oldpolicy = p->policy;
4098 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
4099 policy != SCHED_NORMAL && policy != SCHED_BATCH)
4100 return -EINVAL;
4101 /*
4102 * Valid priorities for SCHED_FIFO and SCHED_RR are
4103 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
4104 * SCHED_BATCH is 0.
4105 */
4106 if (param->sched_priority < 0 ||
4107 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4108 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4109 return -EINVAL;
4110 if ((policy == SCHED_NORMAL || policy == SCHED_BATCH)
4111 != (param->sched_priority == 0))
4112 return -EINVAL;
4114 /*
4115 * Allow unprivileged RT tasks to decrease priority:
4116 */
4117 if (!capable(CAP_SYS_NICE)) {
4118 /*
4119 * can't change policy, except between SCHED_NORMAL
4120 * and SCHED_BATCH:
4121 */
4122 if (((policy != SCHED_NORMAL && p->policy != SCHED_BATCH) &&
4123 (policy != SCHED_BATCH && p->policy != SCHED_NORMAL)) &&
4124 !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
4125 return -EPERM;
4126 /* can't increase priority */
4127 if ((policy != SCHED_NORMAL && policy != SCHED_BATCH) &&
4128 param->sched_priority > p->rt_priority &&
4129 param->sched_priority >
4130 p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
4131 return -EPERM;
4132 /* can't change other user's priorities */
4133 if ((current->euid != p->euid) &&
4134 (current->euid != p->uid))
4135 return -EPERM;
4138 retval = security_task_setscheduler(p, policy, param);
4139 if (retval)
4140 return retval;
4141 /*
4142 * make sure no PI-waiters arrive (or leave) while we are
4143 * changing the priority of the task:
4144 */
4145 spin_lock_irqsave(&p->pi_lock, flags);
4146 /*
4147 * To be able to change p->policy safely, the apropriate
4148 * runqueue lock must be held.
4149 */
4150 rq = __task_rq_lock(p);
4151 /* recheck policy now with rq lock held */
4152 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4153 policy = oldpolicy = -1;
4154 __task_rq_unlock(rq);
4155 spin_unlock_irqrestore(&p->pi_lock, flags);
4156 goto recheck;
4158 array = p->array;
4159 if (array)
4160 deactivate_task(p, rq);
4161 oldprio = p->prio;
4162 __setscheduler(p, policy, param->sched_priority);
4163 if (array) {
4164 __activate_task(p, rq);
4165 /*
4166 * Reschedule if we are currently running on this runqueue and
4167 * our priority decreased, or if we are not currently running on
4168 * this runqueue and our priority is higher than the current's
4169 */
4170 if (task_running(rq, p)) {
4171 if (p->prio > oldprio)
4172 resched_task(rq->curr);
4173 } else if (TASK_PREEMPTS_CURR(p, rq))
4174 resched_task(rq->curr);
4176 __task_rq_unlock(rq);
4177 spin_unlock_irqrestore(&p->pi_lock, flags);
4179 rt_mutex_adjust_pi(p);
4181 return 0;
4183 EXPORT_SYMBOL_GPL(sched_setscheduler);
4185 static int
4186 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4188 struct sched_param lparam;
4189 struct task_struct *p;
4190 int retval;
4192 if (!param || pid < 0)
4193 return -EINVAL;
4194 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4195 return -EFAULT;
4196 read_lock_irq(&tasklist_lock);
4197 p = find_process_by_pid(pid);
4198 if (!p) {
4199 read_unlock_irq(&tasklist_lock);
4200 return -ESRCH;
4202 retval = sched_setscheduler(p, policy, &lparam);
4203 read_unlock_irq(&tasklist_lock);
4205 return retval;
4208 /**
4209 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4210 * @pid: the pid in question.
4211 * @policy: new policy.
4212 * @param: structure containing the new RT priority.
4213 */
4214 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
4215 struct sched_param __user *param)
4217 /* negative values for policy are not valid */
4218 if (policy < 0)
4219 return -EINVAL;
4221 return do_sched_setscheduler(pid, policy, param);
4224 /**
4225 * sys_sched_setparam - set/change the RT priority of a thread
4226 * @pid: the pid in question.
4227 * @param: structure containing the new RT priority.
4228 */
4229 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
4231 return do_sched_setscheduler(pid, -1, param);
4234 /**
4235 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4236 * @pid: the pid in question.
4237 */
4238 asmlinkage long sys_sched_getscheduler(pid_t pid)
4240 struct task_struct *p;
4241 int retval = -EINVAL;
4243 if (pid < 0)
4244 goto out_nounlock;
4246 retval = -ESRCH;
4247 read_lock(&tasklist_lock);
4248 p = find_process_by_pid(pid);
4249 if (p) {
4250 retval = security_task_getscheduler(p);
4251 if (!retval)
4252 retval = p->policy;
4254 read_unlock(&tasklist_lock);
4256 out_nounlock:
4257 return retval;
4260 /**
4261 * sys_sched_getscheduler - get the RT priority of a thread
4262 * @pid: the pid in question.
4263 * @param: structure containing the RT priority.
4264 */
4265 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
4267 struct sched_param lp;
4268 struct task_struct *p;
4269 int retval = -EINVAL;
4271 if (!param || pid < 0)
4272 goto out_nounlock;
4274 read_lock(&tasklist_lock);
4275 p = find_process_by_pid(pid);
4276 retval = -ESRCH;
4277 if (!p)
4278 goto out_unlock;
4280 retval = security_task_getscheduler(p);
4281 if (retval)
4282 goto out_unlock;
4284 lp.sched_priority = p->rt_priority;
4285 read_unlock(&tasklist_lock);
4287 /*
4288 * This one might sleep, we cannot do it with a spinlock held ...
4289 */
4290 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4292 out_nounlock:
4293 return retval;
4295 out_unlock:
4296 read_unlock(&tasklist_lock);
4297 return retval;
4300 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
4302 cpumask_t cpus_allowed;
4303 struct task_struct *p;
4304 int retval;
4306 lock_cpu_hotplug();
4307 read_lock(&tasklist_lock);
4309 p = find_process_by_pid(pid);
4310 if (!p) {
4311 read_unlock(&tasklist_lock);
4312 unlock_cpu_hotplug();
4313 return -ESRCH;
4316 /*
4317 * It is not safe to call set_cpus_allowed with the
4318 * tasklist_lock held. We will bump the task_struct's
4319 * usage count and then drop tasklist_lock.
4320 */
4321 get_task_struct(p);
4322 read_unlock(&tasklist_lock);
4324 retval = -EPERM;
4325 if ((current->euid != p->euid) && (current->euid != p->uid) &&
4326 !capable(CAP_SYS_NICE))
4327 goto out_unlock;
4329 retval = security_task_setscheduler(p, 0, NULL);
4330 if (retval)
4331 goto out_unlock;
4333 cpus_allowed = cpuset_cpus_allowed(p);
4334 cpus_and(new_mask, new_mask, cpus_allowed);
4335 retval = set_cpus_allowed(p, new_mask);
4337 out_unlock:
4338 put_task_struct(p);
4339 unlock_cpu_hotplug();
4340 return retval;
4343 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4344 cpumask_t *new_mask)
4346 if (len < sizeof(cpumask_t)) {
4347 memset(new_mask, 0, sizeof(cpumask_t));
4348 } else if (len > sizeof(cpumask_t)) {
4349 len = sizeof(cpumask_t);
4351 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4354 /**
4355 * sys_sched_setaffinity - set the cpu affinity of a process
4356 * @pid: pid of the process
4357 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4358 * @user_mask_ptr: user-space pointer to the new cpu mask
4359 */
4360 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
4361 unsigned long __user *user_mask_ptr)
4363 cpumask_t new_mask;
4364 int retval;
4366 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
4367 if (retval)
4368 return retval;
4370 return sched_setaffinity(pid, new_mask);
4373 /*
4374 * Represents all cpu's present in the system
4375 * In systems capable of hotplug, this map could dynamically grow
4376 * as new cpu's are detected in the system via any platform specific
4377 * method, such as ACPI for e.g.
4378 */
4380 cpumask_t cpu_present_map __read_mostly;
4381 EXPORT_SYMBOL(cpu_present_map);
4383 #ifndef CONFIG_SMP
4384 cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
4385 cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
4386 #endif
4388 long sched_getaffinity(pid_t pid, cpumask_t *mask)
4390 struct task_struct *p;
4391 int retval;
4393 lock_cpu_hotplug();
4394 read_lock(&tasklist_lock);
4396 retval = -ESRCH;
4397 p = find_process_by_pid(pid);
4398 if (!p)
4399 goto out_unlock;
4401 retval = security_task_getscheduler(p);
4402 if (retval)
4403 goto out_unlock;
4405 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
4407 out_unlock:
4408 read_unlock(&tasklist_lock);
4409 unlock_cpu_hotplug();
4410 if (retval)
4411 return retval;
4413 return 0;
4416 /**
4417 * sys_sched_getaffinity - get the cpu affinity of a process
4418 * @pid: pid of the process
4419 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4420 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4421 */
4422 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
4423 unsigned long __user *user_mask_ptr)
4425 int ret;
4426 cpumask_t mask;
4428 if (len < sizeof(cpumask_t))
4429 return -EINVAL;
4431 ret = sched_getaffinity(pid, &mask);
4432 if (ret < 0)
4433 return ret;
4435 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
4436 return -EFAULT;
4438 return sizeof(cpumask_t);
4441 /**
4442 * sys_sched_yield - yield the current processor to other threads.
4444 * this function yields the current CPU by moving the calling thread
4445 * to the expired array. If there are no other threads running on this
4446 * CPU then this function will return.
4447 */
4448 asmlinkage long sys_sched_yield(void)
4450 struct rq *rq = this_rq_lock();
4451 struct prio_array *array = current->array, *target = rq->expired;
4453 schedstat_inc(rq, yld_cnt);
4454 /*
4455 * We implement yielding by moving the task into the expired
4456 * queue.
4458 * (special rule: RT tasks will just roundrobin in the active
4459 * array.)
4460 */
4461 if (rt_task(current))
4462 target = rq->active;
4464 if (array->nr_active == 1) {
4465 schedstat_inc(rq, yld_act_empty);
4466 if (!rq->expired->nr_active)
4467 schedstat_inc(rq, yld_both_empty);
4468 } else if (!rq->expired->nr_active)
4469 schedstat_inc(rq, yld_exp_empty);
4471 if (array != target) {
4472 dequeue_task(current, array);
4473 enqueue_task(current, target);
4474 } else
4475 /*
4476 * requeue_task is cheaper so perform that if possible.
4477 */
4478 requeue_task(current, array);
4480 /*
4481 * Since we are going to call schedule() anyway, there's
4482 * no need to preempt or enable interrupts:
4483 */
4484 __release(rq->lock);
4485 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4486 _raw_spin_unlock(&rq->lock);
4487 preempt_enable_no_resched();
4489 schedule();
4491 return 0;
4494 static inline int __resched_legal(int expected_preempt_count)
4496 if (unlikely(preempt_count() != expected_preempt_count))
4497 return 0;
4498 if (unlikely(system_state != SYSTEM_RUNNING))
4499 return 0;
4500 return 1;
4503 static void __cond_resched(void)
4505 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4506 __might_sleep(__FILE__, __LINE__);
4507 #endif
4508 /*
4509 * The BKS might be reacquired before we have dropped
4510 * PREEMPT_ACTIVE, which could trigger a second
4511 * cond_resched() call.
4512 */
4513 do {
4514 add_preempt_count(PREEMPT_ACTIVE);
4515 schedule();
4516 sub_preempt_count(PREEMPT_ACTIVE);
4517 } while (need_resched());
4520 int __sched cond_resched(void)
4522 if (need_resched() && __resched_legal(0)) {
4523 __cond_resched();
4524 return 1;
4526 return 0;
4528 EXPORT_SYMBOL(cond_resched);
4530 /*
4531 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4532 * call schedule, and on return reacquire the lock.
4534 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4535 * operations here to prevent schedule() from being called twice (once via
4536 * spin_unlock(), once by hand).
4537 */
4538 int cond_resched_lock(spinlock_t *lock)
4540 int ret = 0;
4542 if (need_lockbreak(lock)) {
4543 spin_unlock(lock);
4544 cpu_relax();
4545 ret = 1;
4546 spin_lock(lock);
4548 if (need_resched() && __resched_legal(1)) {
4549 spin_release(&lock->dep_map, 1, _THIS_IP_);
4550 _raw_spin_unlock(lock);
4551 preempt_enable_no_resched();
4552 __cond_resched();
4553 ret = 1;
4554 spin_lock(lock);
4556 return ret;
4558 EXPORT_SYMBOL(cond_resched_lock);
4560 int __sched cond_resched_softirq(void)
4562 BUG_ON(!in_softirq());
4564 if (need_resched() && __resched_legal(0)) {
4565 raw_local_irq_disable();
4566 _local_bh_enable();
4567 raw_local_irq_enable();
4568 __cond_resched();
4569 local_bh_disable();
4570 return 1;
4572 return 0;
4574 EXPORT_SYMBOL(cond_resched_softirq);
4576 /**
4577 * yield - yield the current processor to other threads.
4579 * this is a shortcut for kernel-space yielding - it marks the
4580 * thread runnable and calls sys_sched_yield().
4581 */
4582 void __sched yield(void)
4584 set_current_state(TASK_RUNNING);
4585 sys_sched_yield();
4587 EXPORT_SYMBOL(yield);
4589 /*
4590 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4591 * that process accounting knows that this is a task in IO wait state.
4593 * But don't do that if it is a deliberate, throttling IO wait (this task
4594 * has set its backing_dev_info: the queue against which it should throttle)
4595 */
4596 void __sched io_schedule(void)
4598 struct rq *rq = &__raw_get_cpu_var(runqueues);
4600 delayacct_blkio_start();
4601 atomic_inc(&rq->nr_iowait);
4602 schedule();
4603 atomic_dec(&rq->nr_iowait);
4604 delayacct_blkio_end();
4606 EXPORT_SYMBOL(io_schedule);
4608 long __sched io_schedule_timeout(long timeout)
4610 struct rq *rq = &__raw_get_cpu_var(runqueues);
4611 long ret;
4613 delayacct_blkio_start();
4614 atomic_inc(&rq->nr_iowait);
4615 ret = schedule_timeout(timeout);
4616 atomic_dec(&rq->nr_iowait);
4617 delayacct_blkio_end();
4618 return ret;
4621 /**
4622 * sys_sched_get_priority_max - return maximum RT priority.
4623 * @policy: scheduling class.
4625 * this syscall returns the maximum rt_priority that can be used
4626 * by a given scheduling class.
4627 */
4628 asmlinkage long sys_sched_get_priority_max(int policy)
4630 int ret = -EINVAL;
4632 switch (policy) {
4633 case SCHED_FIFO:
4634 case SCHED_RR:
4635 ret = MAX_USER_RT_PRIO-1;
4636 break;
4637 case SCHED_NORMAL:
4638 case SCHED_BATCH:
4639 ret = 0;
4640 break;
4642 return ret;
4645 /**
4646 * sys_sched_get_priority_min - return minimum RT priority.
4647 * @policy: scheduling class.
4649 * this syscall returns the minimum rt_priority that can be used
4650 * by a given scheduling class.
4651 */
4652 asmlinkage long sys_sched_get_priority_min(int policy)
4654 int ret = -EINVAL;
4656 switch (policy) {
4657 case SCHED_FIFO:
4658 case SCHED_RR:
4659 ret = 1;
4660 break;
4661 case SCHED_NORMAL:
4662 case SCHED_BATCH:
4663 ret = 0;
4665 return ret;
4668 /**
4669 * sys_sched_rr_get_interval - return the default timeslice of a process.
4670 * @pid: pid of the process.
4671 * @interval: userspace pointer to the timeslice value.
4673 * this syscall writes the default timeslice value of a given process
4674 * into the user-space timespec buffer. A value of '0' means infinity.
4675 */
4676 asmlinkage
4677 long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
4679 struct task_struct *p;
4680 int retval = -EINVAL;
4681 struct timespec t;
4683 if (pid < 0)
4684 goto out_nounlock;
4686 retval = -ESRCH;
4687 read_lock(&tasklist_lock);
4688 p = find_process_by_pid(pid);
4689 if (!p)
4690 goto out_unlock;
4692 retval = security_task_getscheduler(p);
4693 if (retval)
4694 goto out_unlock;
4696 jiffies_to_timespec(p->policy == SCHED_FIFO ?
4697 0 : task_timeslice(p), &t);
4698 read_unlock(&tasklist_lock);
4699 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4700 out_nounlock:
4701 return retval;
4702 out_unlock:
4703 read_unlock(&tasklist_lock);
4704 return retval;
4707 static inline struct task_struct *eldest_child(struct task_struct *p)
4709 if (list_empty(&p->children))
4710 return NULL;
4711 return list_entry(p->children.next,struct task_struct,sibling);
4714 static inline struct task_struct *older_sibling(struct task_struct *p)
4716 if (p->sibling.prev==&p->parent->children)
4717 return NULL;
4718 return list_entry(p->sibling.prev,struct task_struct,sibling);
4721 static inline struct task_struct *younger_sibling(struct task_struct *p)
4723 if (p->sibling.next==&p->parent->children)
4724 return NULL;
4725 return list_entry(p->sibling.next,struct task_struct,sibling);
4728 static const char stat_nam[] = "RSDTtZX";
4730 static void show_task(struct task_struct *p)
4732 struct task_struct *relative;
4733 unsigned long free = 0;
4734 unsigned state;
4736 state = p->state ? __ffs(p->state) + 1 : 0;
4737 printk("%-13.13s %c", p->comm,
4738 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4739 #if (BITS_PER_LONG == 32)
4740 if (state == TASK_RUNNING)
4741 printk(" running ");
4742 else
4743 printk(" %08lX ", thread_saved_pc(p));
4744 #else
4745 if (state == TASK_RUNNING)
4746 printk(" running task ");
4747 else
4748 printk(" %016lx ", thread_saved_pc(p));
4749 #endif
4750 #ifdef CONFIG_DEBUG_STACK_USAGE
4752 unsigned long *n = end_of_stack(p);
4753 while (!*n)
4754 n++;
4755 free = (unsigned long)n - (unsigned long)end_of_stack(p);
4757 #endif
4758 printk("%5lu %5d %6d ", free, p->pid, p->parent->pid);
4759 if ((relative = eldest_child(p)))
4760 printk("%5d ", relative->pid);
4761 else
4762 printk(" ");
4763 if ((relative = younger_sibling(p)))
4764 printk("%7d", relative->pid);
4765 else
4766 printk(" ");
4767 if ((relative = older_sibling(p)))
4768 printk(" %5d", relative->pid);
4769 else
4770 printk(" ");
4771 if (!p->mm)
4772 printk(" (L-TLB)\n");
4773 else
4774 printk(" (NOTLB)\n");
4776 if (state != TASK_RUNNING)
4777 show_stack(p, NULL);
4780 void show_state(void)
4782 struct task_struct *g, *p;
4784 #if (BITS_PER_LONG == 32)
4785 printk("\n"
4786 " sibling\n");
4787 printk(" task PC pid father child younger older\n");
4788 #else
4789 printk("\n"
4790 " sibling\n");
4791 printk(" task PC pid father child younger older\n");
4792 #endif
4793 read_lock(&tasklist_lock);
4794 do_each_thread(g, p) {
4795 /*
4796 * reset the NMI-timeout, listing all files on a slow
4797 * console might take alot of time:
4798 */
4799 touch_nmi_watchdog();
4800 show_task(p);
4801 } while_each_thread(g, p);
4803 read_unlock(&tasklist_lock);
4804 debug_show_all_locks();
4807 /**
4808 * init_idle - set up an idle thread for a given CPU
4809 * @idle: task in question
4810 * @cpu: cpu the idle task belongs to
4812 * NOTE: this function does not set the idle thread's NEED_RESCHED
4813 * flag, to make booting more robust.
4814 */
4815 void __devinit init_idle(struct task_struct *idle, int cpu)
4817 struct rq *rq = cpu_rq(cpu);
4818 unsigned long flags;
4820 idle->timestamp = sched_clock();
4821 idle->sleep_avg = 0;
4822 idle->array = NULL;
4823 idle->prio = idle->normal_prio = MAX_PRIO;
4824 idle->state = TASK_RUNNING;
4825 idle->cpus_allowed = cpumask_of_cpu(cpu);
4826 set_task_cpu(idle, cpu);
4828 spin_lock_irqsave(&rq->lock, flags);
4829 rq->curr = rq->idle = idle;
4830 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4831 idle->oncpu = 1;
4832 #endif
4833 spin_unlock_irqrestore(&rq->lock, flags);
4835 /* Set the preempt count _outside_ the spinlocks! */
4836 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4837 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
4838 #else
4839 task_thread_info(idle)->preempt_count = 0;
4840 #endif
4843 /*
4844 * In a system that switches off the HZ timer nohz_cpu_mask
4845 * indicates which cpus entered this state. This is used
4846 * in the rcu update to wait only for active cpus. For system
4847 * which do not switch off the HZ timer nohz_cpu_mask should
4848 * always be CPU_MASK_NONE.
4849 */
4850 cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
4852 #ifdef CONFIG_SMP
4853 /*
4854 * This is how migration works:
4856 * 1) we queue a struct migration_req structure in the source CPU's
4857 * runqueue and wake up that CPU's migration thread.
4858 * 2) we down() the locked semaphore => thread blocks.
4859 * 3) migration thread wakes up (implicitly it forces the migrated
4860 * thread off the CPU)
4861 * 4) it gets the migration request and checks whether the migrated
4862 * task is still in the wrong runqueue.
4863 * 5) if it's in the wrong runqueue then the migration thread removes
4864 * it and puts it into the right queue.
4865 * 6) migration thread up()s the semaphore.
4866 * 7) we wake up and the migration is done.
4867 */
4869 /*
4870 * Change a given task's CPU affinity. Migrate the thread to a
4871 * proper CPU and schedule it away if the CPU it's executing on
4872 * is removed from the allowed bitmask.
4874 * NOTE: the caller must have a valid reference to the task, the
4875 * task must not exit() & deallocate itself prematurely. The
4876 * call is not atomic; no spinlocks may be held.
4877 */
4878 int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
4880 struct migration_req req;
4881 unsigned long flags;
4882 struct rq *rq;
4883 int ret = 0;
4885 rq = task_rq_lock(p, &flags);
4886 if (!cpus_intersects(new_mask, cpu_online_map)) {
4887 ret = -EINVAL;
4888 goto out;
4891 p->cpus_allowed = new_mask;
4892 /* Can the task run on the task's current CPU? If so, we're done */
4893 if (cpu_isset(task_cpu(p), new_mask))
4894 goto out;
4896 if (migrate_task(p, any_online_cpu(new_mask), &req)) {
4897 /* Need help from migration thread: drop lock and wait. */
4898 task_rq_unlock(rq, &flags);
4899 wake_up_process(rq->migration_thread);
4900 wait_for_completion(&req.done);
4901 tlb_migrate_finish(p->mm);
4902 return 0;
4904 out:
4905 task_rq_unlock(rq, &flags);
4907 return ret;
4909 EXPORT_SYMBOL_GPL(set_cpus_allowed);
4911 /*
4912 * Move (not current) task off this cpu, onto dest cpu. We're doing
4913 * this because either it can't run here any more (set_cpus_allowed()
4914 * away from this CPU, or CPU going down), or because we're
4915 * attempting to rebalance this task on exec (sched_exec).
4917 * So we race with normal scheduler movements, but that's OK, as long
4918 * as the task is no longer on this CPU.
4920 * Returns non-zero if task was successfully migrated.
4921 */
4922 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4924 struct rq *rq_dest, *rq_src;
4925 int ret = 0;
4927 if (unlikely(cpu_is_offline(dest_cpu)))
4928 return ret;
4930 rq_src = cpu_rq(src_cpu);
4931 rq_dest = cpu_rq(dest_cpu);
4933 double_rq_lock(rq_src, rq_dest);
4934 /* Already moved. */
4935 if (task_cpu(p) != src_cpu)
4936 goto out;
4937 /* Affinity changed (again). */
4938 if (!cpu_isset(dest_cpu, p->cpus_allowed))
4939 goto out;
4941 set_task_cpu(p, dest_cpu);
4942 if (p->array) {
4943 /*
4944 * Sync timestamp with rq_dest's before activating.
4945 * The same thing could be achieved by doing this step
4946 * afterwards, and pretending it was a local activate.
4947 * This way is cleaner and logically correct.
4948 */
4949 p->timestamp = p->timestamp - rq_src->timestamp_last_tick
4950 + rq_dest->timestamp_last_tick;
4951 deactivate_task(p, rq_src);
4952 __activate_task(p, rq_dest);
4953 if (TASK_PREEMPTS_CURR(p, rq_dest))
4954 resched_task(rq_dest->curr);
4956 ret = 1;
4957 out:
4958 double_rq_unlock(rq_src, rq_dest);
4959 return ret;
4962 /*
4963 * migration_thread - this is a highprio system thread that performs
4964 * thread migration by bumping thread off CPU then 'pushing' onto
4965 * another runqueue.
4966 */
4967 static int migration_thread(void *data)
4969 int cpu = (long)data;
4970 struct rq *rq;
4972 rq = cpu_rq(cpu);
4973 BUG_ON(rq->migration_thread != current);
4975 set_current_state(TASK_INTERRUPTIBLE);
4976 while (!kthread_should_stop()) {
4977 struct migration_req *req;
4978 struct list_head *head;
4980 try_to_freeze();
4982 spin_lock_irq(&rq->lock);
4984 if (cpu_is_offline(cpu)) {
4985 spin_unlock_irq(&rq->lock);
4986 goto wait_to_die;
4989 if (rq->active_balance) {
4990 active_load_balance(rq, cpu);
4991 rq->active_balance = 0;
4994 head = &rq->migration_queue;
4996 if (list_empty(head)) {
4997 spin_unlock_irq(&rq->lock);
4998 schedule();
4999 set_current_state(TASK_INTERRUPTIBLE);
5000 continue;
5002 req = list_entry(head->next, struct migration_req, list);
5003 list_del_init(head->next);
5005 spin_unlock(&rq->lock);
5006 __migrate_task(req->task, cpu, req->dest_cpu);
5007 local_irq_enable();
5009 complete(&req->done);
5011 __set_current_state(TASK_RUNNING);
5012 return 0;
5014 wait_to_die:
5015 /* Wait for kthread_stop */
5016 set_current_state(TASK_INTERRUPTIBLE);
5017 while (!kthread_should_stop()) {
5018 schedule();
5019 set_current_state(TASK_INTERRUPTIBLE);
5021 __set_current_state(TASK_RUNNING);
5022 return 0;
5025 #ifdef CONFIG_HOTPLUG_CPU
5026 /* Figure out where task on dead CPU should go, use force if neccessary. */
5027 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
5029 unsigned long flags;
5030 cpumask_t mask;
5031 struct rq *rq;
5032 int dest_cpu;
5034 restart:
5035 /* On same node? */
5036 mask = node_to_cpumask(cpu_to_node(dead_cpu));
5037 cpus_and(mask, mask, p->cpus_allowed);
5038 dest_cpu = any_online_cpu(mask);
5040 /* On any allowed CPU? */
5041 if (dest_cpu == NR_CPUS)
5042 dest_cpu = any_online_cpu(p->cpus_allowed);
5044 /* No more Mr. Nice Guy. */
5045 if (dest_cpu == NR_CPUS) {
5046 rq = task_rq_lock(p, &flags);
5047 cpus_setall(p->cpus_allowed);
5048 dest_cpu = any_online_cpu(p->cpus_allowed);
5049 task_rq_unlock(rq, &flags);
5051 /*
5052 * Don't tell them about moving exiting tasks or
5053 * kernel threads (both mm NULL), since they never
5054 * leave kernel.
5055 */
5056 if (p->mm && printk_ratelimit())
5057 printk(KERN_INFO "process %d (%s) no "
5058 "longer affine to cpu%d\n",
5059 p->pid, p->comm, dead_cpu);
5061 if (!__migrate_task(p, dead_cpu, dest_cpu))
5062 goto restart;
5065 /*
5066 * While a dead CPU has no uninterruptible tasks queued at this point,
5067 * it might still have a nonzero ->nr_uninterruptible counter, because
5068 * for performance reasons the counter is not stricly tracking tasks to
5069 * their home CPUs. So we just add the counter to another CPU's counter,
5070 * to keep the global sum constant after CPU-down:
5071 */
5072 static void migrate_nr_uninterruptible(struct rq *rq_src)
5074 struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
5075 unsigned long flags;
5077 local_irq_save(flags);
5078 double_rq_lock(rq_src, rq_dest);
5079 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5080 rq_src->nr_uninterruptible = 0;
5081 double_rq_unlock(rq_src, rq_dest);
5082 local_irq_restore(flags);
5085 /* Run through task list and migrate tasks from the dead cpu. */
5086 static void migrate_live_tasks(int src_cpu)
5088 struct task_struct *p, *t;
5090 write_lock_irq(&tasklist_lock);
5092 do_each_thread(t, p) {
5093 if (p == current)
5094 continue;
5096 if (task_cpu(p) == src_cpu)
5097 move_task_off_dead_cpu(src_cpu, p);
5098 } while_each_thread(t, p);
5100 write_unlock_irq(&tasklist_lock);
5103 /* Schedules idle task to be the next runnable task on current CPU.
5104 * It does so by boosting its priority to highest possible and adding it to
5105 * the _front_ of the runqueue. Used by CPU offline code.
5106 */
5107 void sched_idle_next(void)
5109 int this_cpu = smp_processor_id();
5110 struct rq *rq = cpu_rq(this_cpu);
5111 struct task_struct *p = rq->idle;
5112 unsigned long flags;
5114 /* cpu has to be offline */
5115 BUG_ON(cpu_online(this_cpu));
5117 /*
5118 * Strictly not necessary since rest of the CPUs are stopped by now
5119 * and interrupts disabled on the current cpu.
5120 */
5121 spin_lock_irqsave(&rq->lock, flags);
5123 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
5125 /* Add idle task to the _front_ of its priority queue: */
5126 __activate_idle_task(p, rq);
5128 spin_unlock_irqrestore(&rq->lock, flags);
5131 /*
5132 * Ensures that the idle task is using init_mm right before its cpu goes
5133 * offline.
5134 */
5135 void idle_task_exit(void)
5137 struct mm_struct *mm = current->active_mm;
5139 BUG_ON(cpu_online(smp_processor_id()));
5141 if (mm != &init_mm)
5142 switch_mm(mm, &init_mm, current);
5143 mmdrop(mm);
5146 static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
5148 struct rq *rq = cpu_rq(dead_cpu);
5150 /* Must be exiting, otherwise would be on tasklist. */
5151 BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
5153 /* Cannot have done final schedule yet: would have vanished. */
5154 BUG_ON(p->flags & PF_DEAD);
5156 get_task_struct(p);
5158 /*
5159 * Drop lock around migration; if someone else moves it,
5160 * that's OK. No task can be added to this CPU, so iteration is
5161 * fine.
5162 */
5163 spin_unlock_irq(&rq->lock);
5164 move_task_off_dead_cpu(dead_cpu, p);
5165 spin_lock_irq(&rq->lock);
5167 put_task_struct(p);
5170 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5171 static void migrate_dead_tasks(unsigned int dead_cpu)
5173 struct rq *rq = cpu_rq(dead_cpu);
5174 unsigned int arr, i;
5176 for (arr = 0; arr < 2; arr++) {
5177 for (i = 0; i < MAX_PRIO; i++) {
5178 struct list_head *list = &rq->arrays[arr].queue[i];
5180 while (!list_empty(list))
5181 migrate_dead(dead_cpu, list_entry(list->next,
5182 struct task_struct, run_list));
5186 #endif /* CONFIG_HOTPLUG_CPU */
5188 /*
5189 * migration_call - callback that gets triggered when a CPU is added.
5190 * Here we can start up the necessary migration thread for the new CPU.
5191 */
5192 static int __cpuinit
5193 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5195 struct task_struct *p;
5196 int cpu = (long)hcpu;
5197 unsigned long flags;
5198 struct rq *rq;
5200 switch (action) {
5201 case CPU_UP_PREPARE:
5202 p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
5203 if (IS_ERR(p))
5204 return NOTIFY_BAD;
5205 p->flags |= PF_NOFREEZE;
5206 kthread_bind(p, cpu);
5207 /* Must be high prio: stop_machine expects to yield to it. */
5208 rq = task_rq_lock(p, &flags);
5209 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
5210 task_rq_unlock(rq, &flags);
5211 cpu_rq(cpu)->migration_thread = p;
5212 break;
5214 case CPU_ONLINE:
5215 /* Strictly unneccessary, as first user will wake it. */
5216 wake_up_process(cpu_rq(cpu)->migration_thread);
5217 break;
5219 #ifdef CONFIG_HOTPLUG_CPU
5220 case CPU_UP_CANCELED:
5221 if (!cpu_rq(cpu)->migration_thread)
5222 break;
5223 /* Unbind it from offline cpu so it can run. Fall thru. */
5224 kthread_bind(cpu_rq(cpu)->migration_thread,
5225 any_online_cpu(cpu_online_map));
5226 kthread_stop(cpu_rq(cpu)->migration_thread);
5227 cpu_rq(cpu)->migration_thread = NULL;
5228 break;
5230 case CPU_DEAD:
5231 migrate_live_tasks(cpu);
5232 rq = cpu_rq(cpu);
5233 kthread_stop(rq->migration_thread);
5234 rq->migration_thread = NULL;
5235 /* Idle task back to normal (off runqueue, low prio) */
5236 rq = task_rq_lock(rq->idle, &flags);
5237 deactivate_task(rq->idle, rq);
5238 rq->idle->static_prio = MAX_PRIO;
5239 __setscheduler(rq->idle, SCHED_NORMAL, 0);
5240 migrate_dead_tasks(cpu);
5241 task_rq_unlock(rq, &flags);
5242 migrate_nr_uninterruptible(rq);
5243 BUG_ON(rq->nr_running != 0);
5245 /* No need to migrate the tasks: it was best-effort if
5246 * they didn't do lock_cpu_hotplug(). Just wake up
5247 * the requestors. */
5248 spin_lock_irq(&rq->lock);
5249 while (!list_empty(&rq->migration_queue)) {
5250 struct migration_req *req;
5252 req = list_entry(rq->migration_queue.next,
5253 struct migration_req, list);
5254 list_del_init(&req->list);
5255 complete(&req->done);
5257 spin_unlock_irq(&rq->lock);
5258 break;
5259 #endif
5261 return NOTIFY_OK;
5264 /* Register at highest priority so that task migration (migrate_all_tasks)
5265 * happens before everything else.
5266 */
5267 static struct notifier_block __cpuinitdata migration_notifier = {
5268 .notifier_call = migration_call,
5269 .priority = 10
5270 };
5272 int __init migration_init(void)
5274 void *cpu = (void *)(long)smp_processor_id();
5276 /* Start one for the boot CPU: */
5277 migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5278 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5279 register_cpu_notifier(&migration_notifier);
5281 return 0;
5283 #endif
5285 #ifdef CONFIG_SMP
5286 #undef SCHED_DOMAIN_DEBUG
5287 #ifdef SCHED_DOMAIN_DEBUG
5288 static void sched_domain_debug(struct sched_domain *sd, int cpu)
5290 int level = 0;
5292 if (!sd) {
5293 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5294 return;
5297 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5299 do {
5300 int i;
5301 char str[NR_CPUS];
5302 struct sched_group *group = sd->groups;
5303 cpumask_t groupmask;
5305 cpumask_scnprintf(str, NR_CPUS, sd->span);
5306 cpus_clear(groupmask);
5308 printk(KERN_DEBUG);
5309 for (i = 0; i < level + 1; i++)
5310 printk(" ");
5311 printk("domain %d: ", level);
5313 if (!(sd->flags & SD_LOAD_BALANCE)) {
5314 printk("does not load-balance\n");
5315 if (sd->parent)
5316 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent");
5317 break;
5320 printk("span %s\n", str);
5322 if (!cpu_isset(cpu, sd->span))
5323 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
5324 if (!cpu_isset(cpu, group->cpumask))
5325 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
5327 printk(KERN_DEBUG);
5328 for (i = 0; i < level + 2; i++)
5329 printk(" ");
5330 printk("groups:");
5331 do {
5332 if (!group) {
5333 printk("\n");
5334 printk(KERN_ERR "ERROR: group is NULL\n");
5335 break;
5338 if (!group->cpu_power) {
5339 printk("\n");
5340 printk(KERN_ERR "ERROR: domain->cpu_power not set\n");
5343 if (!cpus_weight(group->cpumask)) {
5344 printk("\n");
5345 printk(KERN_ERR "ERROR: empty group\n");
5348 if (cpus_intersects(groupmask, group->cpumask)) {
5349 printk("\n");
5350 printk(KERN_ERR "ERROR: repeated CPUs\n");
5353 cpus_or(groupmask, groupmask, group->cpumask);
5355 cpumask_scnprintf(str, NR_CPUS, group->cpumask);
5356 printk(" %s", str);
5358 group = group->next;
5359 } while (group != sd->groups);
5360 printk("\n");
5362 if (!cpus_equal(sd->span, groupmask))
5363 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5365 level++;
5366 sd = sd->parent;
5368 if (sd) {
5369 if (!cpus_subset(groupmask, sd->span))
5370 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
5373 } while (sd);
5375 #else
5376 # define sched_domain_debug(sd, cpu) do { } while (0)
5377 #endif
5379 static int sd_degenerate(struct sched_domain *sd)
5381 if (cpus_weight(sd->span) == 1)
5382 return 1;
5384 /* Following flags need at least 2 groups */
5385 if (sd->flags & (SD_LOAD_BALANCE |
5386 SD_BALANCE_NEWIDLE |
5387 SD_BALANCE_FORK |
5388 SD_BALANCE_EXEC)) {
5389 if (sd->groups != sd->groups->next)
5390 return 0;
5393 /* Following flags don't use groups */
5394 if (sd->flags & (SD_WAKE_IDLE |
5395 SD_WAKE_AFFINE |
5396 SD_WAKE_BALANCE))
5397 return 0;
5399 return 1;
5402 static int
5403 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5405 unsigned long cflags = sd->flags, pflags = parent->flags;
5407 if (sd_degenerate(parent))
5408 return 1;
5410 if (!cpus_equal(sd->span, parent->span))
5411 return 0;
5413 /* Does parent contain flags not in child? */
5414 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5415 if (cflags & SD_WAKE_AFFINE)
5416 pflags &= ~SD_WAKE_BALANCE;
5417 /* Flags needing groups don't count if only 1 group in parent */
5418 if (parent->groups == parent->groups->next) {
5419 pflags &= ~(SD_LOAD_BALANCE |
5420 SD_BALANCE_NEWIDLE |
5421 SD_BALANCE_FORK |
5422 SD_BALANCE_EXEC);
5424 if (~cflags & pflags)
5425 return 0;
5427 return 1;
5430 /*
5431 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5432 * hold the hotplug lock.
5433 */
5434 static void cpu_attach_domain(struct sched_domain *sd, int cpu)
5436 struct rq *rq = cpu_rq(cpu);
5437 struct sched_domain *tmp;
5439 /* Remove the sched domains which do not contribute to scheduling. */
5440 for (tmp = sd; tmp; tmp = tmp->parent) {
5441 struct sched_domain *parent = tmp->parent;
5442 if (!parent)
5443 break;
5444 if (sd_parent_degenerate(tmp, parent))
5445 tmp->parent = parent->parent;
5448 if (sd && sd_degenerate(sd))
5449 sd = sd->parent;
5451 sched_domain_debug(sd, cpu);
5453 rcu_assign_pointer(rq->sd, sd);
5456 /* cpus with isolated domains */
5457 static cpumask_t __devinitdata cpu_isolated_map = CPU_MASK_NONE;
5459 /* Setup the mask of cpus configured for isolated domains */
5460 static int __init isolated_cpu_setup(char *str)
5462 int ints[NR_CPUS], i;
5464 str = get_options(str, ARRAY_SIZE(ints), ints);
5465 cpus_clear(cpu_isolated_map);
5466 for (i = 1; i <= ints[0]; i++)
5467 if (ints[i] < NR_CPUS)
5468 cpu_set(ints[i], cpu_isolated_map);
5469 return 1;
5472 __setup ("isolcpus=", isolated_cpu_setup);
5474 /*
5475 * init_sched_build_groups takes an array of groups, the cpumask we wish
5476 * to span, and a pointer to a function which identifies what group a CPU
5477 * belongs to. The return value of group_fn must be a valid index into the
5478 * groups[] array, and must be >= 0 and < NR_CPUS (due to the fact that we
5479 * keep track of groups covered with a cpumask_t).
5481 * init_sched_build_groups will build a circular linked list of the groups
5482 * covered by the given span, and will set each group's ->cpumask correctly,
5483 * and ->cpu_power to 0.
5484 */
5485 static void init_sched_build_groups(struct sched_group groups[], cpumask_t span,
5486 int (*group_fn)(int cpu))
5488 struct sched_group *first = NULL, *last = NULL;
5489 cpumask_t covered = CPU_MASK_NONE;
5490 int i;
5492 for_each_cpu_mask(i, span) {
5493 int group = group_fn(i);
5494 struct sched_group *sg = &groups[group];
5495 int j;
5497 if (cpu_isset(i, covered))
5498 continue;
5500 sg->cpumask = CPU_MASK_NONE;
5501 sg->cpu_power = 0;
5503 for_each_cpu_mask(j, span) {
5504 if (group_fn(j) != group)
5505 continue;
5507 cpu_set(j, covered);
5508 cpu_set(j, sg->cpumask);
5510 if (!first)
5511 first = sg;
5512 if (last)
5513 last->next = sg;
5514 last = sg;
5516 last->next = first;
5519 #define SD_NODES_PER_DOMAIN 16
5521 /*
5522 * Self-tuning task migration cost measurement between source and target CPUs.
5524 * This is done by measuring the cost of manipulating buffers of varying
5525 * sizes. For a given buffer-size here are the steps that are taken:
5527 * 1) the source CPU reads+dirties a shared buffer
5528 * 2) the target CPU reads+dirties the same shared buffer
5530 * We measure how long they take, in the following 4 scenarios:
5532 * - source: CPU1, target: CPU2 | cost1
5533 * - source: CPU2, target: CPU1 | cost2
5534 * - source: CPU1, target: CPU1 | cost3
5535 * - source: CPU2, target: CPU2 | cost4
5537 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5538 * the cost of migration.
5540 * We then start off from a small buffer-size and iterate up to larger
5541 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5542 * doing a maximum search for the cost. (The maximum cost for a migration
5543 * normally occurs when the working set size is around the effective cache
5544 * size.)
5545 */
5546 #define SEARCH_SCOPE 2
5547 #define MIN_CACHE_SIZE (64*1024U)
5548 #define DEFAULT_CACHE_SIZE (5*1024*1024U)
5549 #define ITERATIONS 1
5550 #define SIZE_THRESH 130
5551 #define COST_THRESH 130
5553 /*
5554 * The migration cost is a function of 'domain distance'. Domain
5555 * distance is the number of steps a CPU has to iterate down its
5556 * domain tree to share a domain with the other CPU. The farther
5557 * two CPUs are from each other, the larger the distance gets.
5559 * Note that we use the distance only to cache measurement results,
5560 * the distance value is not used numerically otherwise. When two
5561 * CPUs have the same distance it is assumed that the migration
5562 * cost is the same. (this is a simplification but quite practical)
5563 */
5564 #define MAX_DOMAIN_DISTANCE 32
5566 static unsigned long long migration_cost[MAX_DOMAIN_DISTANCE] =
5567 { [ 0 ... MAX_DOMAIN_DISTANCE-1 ] =
5568 /*
5569 * Architectures may override the migration cost and thus avoid
5570 * boot-time calibration. Unit is nanoseconds. Mostly useful for
5571 * virtualized hardware:
5572 */
5573 #ifdef CONFIG_DEFAULT_MIGRATION_COST
5574 CONFIG_DEFAULT_MIGRATION_COST
5575 #else
5576 -1LL
5577 #endif
5578 };
5580 /*
5581 * Allow override of migration cost - in units of microseconds.
5582 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5583 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5584 */
5585 static int __init migration_cost_setup(char *str)
5587 int ints[MAX_DOMAIN_DISTANCE+1], i;
5589 str = get_options(str, ARRAY_SIZE(ints), ints);
5591 printk("#ints: %d\n", ints[0]);
5592 for (i = 1; i <= ints[0]; i++) {
5593 migration_cost[i-1] = (unsigned long long)ints[i]*1000;
5594 printk("migration_cost[%d]: %Ld\n", i-1, migration_cost[i-1]);
5596 return 1;
5599 __setup ("migration_cost=", migration_cost_setup);
5601 /*
5602 * Global multiplier (divisor) for migration-cutoff values,
5603 * in percentiles. E.g. use a value of 150 to get 1.5 times
5604 * longer cache-hot cutoff times.
5606 * (We scale it from 100 to 128 to long long handling easier.)
5607 */
5609 #define MIGRATION_FACTOR_SCALE 128
5611 static unsigned int migration_factor = MIGRATION_FACTOR_SCALE;
5613 static int __init setup_migration_factor(char *str)
5615 get_option(&str, &migration_factor);
5616 migration_factor = migration_factor * MIGRATION_FACTOR_SCALE / 100;
5617 return 1;
5620 __setup("migration_factor=", setup_migration_factor);
5622 /*
5623 * Estimated distance of two CPUs, measured via the number of domains
5624 * we have to pass for the two CPUs to be in the same span:
5625 */
5626 static unsigned long domain_distance(int cpu1, int cpu2)
5628 unsigned long distance = 0;
5629 struct sched_domain *sd;
5631 for_each_domain(cpu1, sd) {
5632 WARN_ON(!cpu_isset(cpu1, sd->span));
5633 if (cpu_isset(cpu2, sd->span))
5634 return distance;
5635 distance++;
5637 if (distance >= MAX_DOMAIN_DISTANCE) {
5638 WARN_ON(1);
5639 distance = MAX_DOMAIN_DISTANCE-1;
5642 return distance;
5645 static unsigned int migration_debug;
5647 static int __init setup_migration_debug(char *str)
5649 get_option(&str, &migration_debug);
5650 return 1;
5653 __setup("migration_debug=", setup_migration_debug);
5655 /*
5656 * Maximum cache-size that the scheduler should try to measure.
5657 * Architectures with larger caches should tune this up during
5658 * bootup. Gets used in the domain-setup code (i.e. during SMP
5659 * bootup).
5660 */
5661 unsigned int max_cache_size;
5663 static int __init setup_max_cache_size(char *str)
5665 get_option(&str, &max_cache_size);
5666 return 1;
5669 __setup("max_cache_size=", setup_max_cache_size);
5671 /*
5672 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5673 * is the operation that is timed, so we try to generate unpredictable
5674 * cachemisses that still end up filling the L2 cache:
5675 */
5676 static void touch_cache(void *__cache, unsigned long __size)
5678 unsigned long size = __size/sizeof(long), chunk1 = size/3,
5679 chunk2 = 2*size/3;
5680 unsigned long *cache = __cache;
5681 int i;
5683 for (i = 0; i < size/6; i += 8) {
5684 switch (i % 6) {
5685 case 0: cache[i]++;
5686 case 1: cache[size-1-i]++;
5687 case 2: cache[chunk1-i]++;
5688 case 3: cache[chunk1+i]++;
5689 case 4: cache[chunk2-i]++;
5690 case 5: cache[chunk2+i]++;
5695 /*
5696 * Measure the cache-cost of one task migration. Returns in units of nsec.
5697 */
5698 static unsigned long long
5699 measure_one(void *cache, unsigned long size, int source, int target)
5701 cpumask_t mask, saved_mask;
5702 unsigned long long t0, t1, t2, t3, cost;
5704 saved_mask = current->cpus_allowed;
5706 /*
5707 * Flush source caches to RAM and invalidate them:
5708 */
5709 sched_cacheflush();
5711 /*
5712 * Migrate to the source CPU:
5713 */
5714 mask = cpumask_of_cpu(source);
5715 set_cpus_allowed(current, mask);
5716 WARN_ON(smp_processor_id() != source);
5718 /*
5719 * Dirty the working set:
5720 */
5721 t0 = sched_clock();
5722 touch_cache(cache, size);
5723 t1 = sched_clock();
5725 /*
5726 * Migrate to the target CPU, dirty the L2 cache and access
5727 * the shared buffer. (which represents the working set
5728 * of a migrated task.)
5729 */
5730 mask = cpumask_of_cpu(target);
5731 set_cpus_allowed(current, mask);
5732 WARN_ON(smp_processor_id() != target);
5734 t2 = sched_clock();
5735 touch_cache(cache, size);
5736 t3 = sched_clock();
5738 cost = t1-t0 + t3-t2;
5740 if (migration_debug >= 2)
5741 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5742 source, target, t1-t0, t1-t0, t3-t2, cost);
5743 /*
5744 * Flush target caches to RAM and invalidate them:
5745 */
5746 sched_cacheflush();
5748 set_cpus_allowed(current, saved_mask);
5750 return cost;
5753 /*
5754 * Measure a series of task migrations and return the average
5755 * result. Since this code runs early during bootup the system
5756 * is 'undisturbed' and the average latency makes sense.
5758 * The algorithm in essence auto-detects the relevant cache-size,
5759 * so it will properly detect different cachesizes for different
5760 * cache-hierarchies, depending on how the CPUs are connected.
5762 * Architectures can prime the upper limit of the search range via
5763 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5764 */
5765 static unsigned long long
5766 measure_cost(int cpu1, int cpu2, void *cache, unsigned int size)
5768 unsigned long long cost1, cost2;
5769 int i;
5771 /*
5772 * Measure the migration cost of 'size' bytes, over an
5773 * average of 10 runs:
5775 * (We perturb the cache size by a small (0..4k)
5776 * value to compensate size/alignment related artifacts.
5777 * We also subtract the cost of the operation done on
5778 * the same CPU.)
5779 */
5780 cost1 = 0;
5782 /*
5783 * dry run, to make sure we start off cache-cold on cpu1,
5784 * and to get any vmalloc pagefaults in advance:
5785 */
5786 measure_one(cache, size, cpu1, cpu2);
5787 for (i = 0; i < ITERATIONS; i++)
5788 cost1 += measure_one(cache, size - i*1024, cpu1, cpu2);
5790 measure_one(cache, size, cpu2, cpu1);
5791 for (i = 0; i < ITERATIONS; i++)
5792 cost1 += measure_one(cache, size - i*1024, cpu2, cpu1);
5794 /*
5795 * (We measure the non-migrating [cached] cost on both
5796 * cpu1 and cpu2, to handle CPUs with different speeds)
5797 */
5798 cost2 = 0;
5800 measure_one(cache, size, cpu1, cpu1);
5801 for (i = 0; i < ITERATIONS; i++)
5802 cost2 += measure_one(cache, size - i*1024, cpu1, cpu1);
5804 measure_one(cache, size, cpu2, cpu2);
5805 for (i = 0; i < ITERATIONS; i++)
5806 cost2 += measure_one(cache, size - i*1024, cpu2, cpu2);
5808 /*
5809 * Get the per-iteration migration cost:
5810 */
5811 do_div(cost1, 2*ITERATIONS);
5812 do_div(cost2, 2*ITERATIONS);
5814 return cost1 - cost2;
5817 static unsigned long long measure_migration_cost(int cpu1, int cpu2)
5819 unsigned long long max_cost = 0, fluct = 0, avg_fluct = 0;
5820 unsigned int max_size, size, size_found = 0;
5821 long long cost = 0, prev_cost;
5822 void *cache;
5824 /*
5825 * Search from max_cache_size*5 down to 64K - the real relevant
5826 * cachesize has to lie somewhere inbetween.
5827 */
5828 if (max_cache_size) {
5829 max_size = max(max_cache_size * SEARCH_SCOPE, MIN_CACHE_SIZE);
5830 size = max(max_cache_size / SEARCH_SCOPE, MIN_CACHE_SIZE);
5831 } else {
5832 /*
5833 * Since we have no estimation about the relevant
5834 * search range
5835 */
5836 max_size = DEFAULT_CACHE_SIZE * SEARCH_SCOPE;
5837 size = MIN_CACHE_SIZE;
5840 if (!cpu_online(cpu1) || !cpu_online(cpu2)) {
5841 printk("cpu %d and %d not both online!\n", cpu1, cpu2);
5842 return 0;
5845 /*
5846 * Allocate the working set:
5847 */
5848 cache = vmalloc(max_size);
5849 if (!cache) {
5850 printk("could not vmalloc %d bytes for cache!\n", 2*max_size);
5851 return 1000000; /* return 1 msec on very small boxen */
5854 while (size <= max_size) {
5855 prev_cost = cost;
5856 cost = measure_cost(cpu1, cpu2, cache, size);
5858 /*
5859 * Update the max:
5860 */
5861 if (cost > 0) {
5862 if (max_cost < cost) {
5863 max_cost = cost;
5864 size_found = size;
5867 /*
5868 * Calculate average fluctuation, we use this to prevent
5869 * noise from triggering an early break out of the loop:
5870 */
5871 fluct = abs(cost - prev_cost);
5872 avg_fluct = (avg_fluct + fluct)/2;
5874 if (migration_debug)
5875 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): (%8Ld %8Ld)\n",
5876 cpu1, cpu2, size,
5877 (long)cost / 1000000,
5878 ((long)cost / 100000) % 10,
5879 (long)max_cost / 1000000,
5880 ((long)max_cost / 100000) % 10,
5881 domain_distance(cpu1, cpu2),
5882 cost, avg_fluct);
5884 /*
5885 * If we iterated at least 20% past the previous maximum,
5886 * and the cost has dropped by more than 20% already,
5887 * (taking fluctuations into account) then we assume to
5888 * have found the maximum and break out of the loop early:
5889 */
5890 if (size_found && (size*100 > size_found*SIZE_THRESH))
5891 if (cost+avg_fluct <= 0 ||
5892 max_cost*100 > (cost+avg_fluct)*COST_THRESH) {
5894 if (migration_debug)
5895 printk("-> found max.\n");
5896 break;
5898 /*
5899 * Increase the cachesize in 10% steps:
5900 */
5901 size = size * 10 / 9;
5904 if (migration_debug)
5905 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
5906 cpu1, cpu2, size_found, max_cost);
5908 vfree(cache);
5910 /*
5911 * A task is considered 'cache cold' if at least 2 times
5912 * the worst-case cost of migration has passed.
5914 * (this limit is only listened to if the load-balancing
5915 * situation is 'nice' - if there is a large imbalance we
5916 * ignore it for the sake of CPU utilization and
5917 * processing fairness.)
5918 */
5919 return 2 * max_cost * migration_factor / MIGRATION_FACTOR_SCALE;
5922 static void calibrate_migration_costs(const cpumask_t *cpu_map)
5924 int cpu1 = -1, cpu2 = -1, cpu, orig_cpu = raw_smp_processor_id();
5925 unsigned long j0, j1, distance, max_distance = 0;
5926 struct sched_domain *sd;
5928 j0 = jiffies;
5930 /*
5931 * First pass - calculate the cacheflush times:
5932 */
5933 for_each_cpu_mask(cpu1, *cpu_map) {
5934 for_each_cpu_mask(cpu2, *cpu_map) {
5935 if (cpu1 == cpu2)
5936 continue;
5937 distance = domain_distance(cpu1, cpu2);
5938 max_distance = max(max_distance, distance);
5939 /*
5940 * No result cached yet?
5941 */
5942 if (migration_cost[distance] == -1LL)
5943 migration_cost[distance] =
5944 measure_migration_cost(cpu1, cpu2);
5947 /*
5948 * Second pass - update the sched domain hierarchy with
5949 * the new cache-hot-time estimations:
5950 */
5951 for_each_cpu_mask(cpu, *cpu_map) {
5952 distance = 0;
5953 for_each_domain(cpu, sd) {
5954 sd->cache_hot_time = migration_cost[distance];
5955 distance++;
5958 /*
5959 * Print the matrix:
5960 */
5961 if (migration_debug)
5962 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
5963 max_cache_size,
5964 #ifdef CONFIG_X86
5965 cpu_khz/1000
5966 #else
5967 -1
5968 #endif
5969 );
5970 if (system_state == SYSTEM_BOOTING) {
5971 printk("migration_cost=");
5972 for (distance = 0; distance <= max_distance; distance++) {
5973 if (distance)
5974 printk(",");
5975 printk("%ld", (long)migration_cost[distance] / 1000);
5977 printk("\n");
5979 j1 = jiffies;
5980 if (migration_debug)
5981 printk("migration: %ld seconds\n", (j1-j0)/HZ);
5983 /*
5984 * Move back to the original CPU. NUMA-Q gets confused
5985 * if we migrate to another quad during bootup.
5986 */
5987 if (raw_smp_processor_id() != orig_cpu) {
5988 cpumask_t mask = cpumask_of_cpu(orig_cpu),
5989 saved_mask = current->cpus_allowed;
5991 set_cpus_allowed(current, mask);
5992 set_cpus_allowed(current, saved_mask);
5996 #ifdef CONFIG_NUMA
5998 /**
5999 * find_next_best_node - find the next node to include in a sched_domain
6000 * @node: node whose sched_domain we're building
6001 * @used_nodes: nodes already in the sched_domain
6003 * Find the next node to include in a given scheduling domain. Simply
6004 * finds the closest node not already in the @used_nodes map.
6006 * Should use nodemask_t.
6007 */
6008 static int find_next_best_node(int node, unsigned long *used_nodes)
6010 int i, n, val, min_val, best_node = 0;
6012 min_val = INT_MAX;
6014 for (i = 0; i < MAX_NUMNODES; i++) {
6015 /* Start at @node */
6016 n = (node + i) % MAX_NUMNODES;
6018 if (!nr_cpus_node(n))
6019 continue;
6021 /* Skip already used nodes */
6022 if (test_bit(n, used_nodes))
6023 continue;
6025 /* Simple min distance search */
6026 val = node_distance(node, n);
6028 if (val < min_val) {
6029 min_val = val;
6030 best_node = n;
6034 set_bit(best_node, used_nodes);
6035 return best_node;
6038 /**
6039 * sched_domain_node_span - get a cpumask for a node's sched_domain
6040 * @node: node whose cpumask we're constructing
6041 * @size: number of nodes to include in this span
6043 * Given a node, construct a good cpumask for its sched_domain to span. It
6044 * should be one that prevents unnecessary balancing, but also spreads tasks
6045 * out optimally.
6046 */
6047 static cpumask_t sched_domain_node_span(int node)
6049 DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
6050 cpumask_t span, nodemask;
6051 int i;
6053 cpus_clear(span);
6054 bitmap_zero(used_nodes, MAX_NUMNODES);
6056 nodemask = node_to_cpumask(node);
6057 cpus_or(span, span, nodemask);
6058 set_bit(node, used_nodes);
6060 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
6061 int next_node = find_next_best_node(node, used_nodes);
6063 nodemask = node_to_cpumask(next_node);
6064 cpus_or(span, span, nodemask);
6067 return span;
6069 #endif
6071 int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
6073 /*
6074 * SMT sched-domains:
6075 */
6076 #ifdef CONFIG_SCHED_SMT
6077 static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
6078 static struct sched_group sched_group_cpus[NR_CPUS];
6080 static int cpu_to_cpu_group(int cpu)
6082 return cpu;
6084 #endif
6086 /*
6087 * multi-core sched-domains:
6088 */
6089 #ifdef CONFIG_SCHED_MC
6090 static DEFINE_PER_CPU(struct sched_domain, core_domains);
6091 static struct sched_group *sched_group_core_bycpu[NR_CPUS];
6092 #endif
6094 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6095 static int cpu_to_core_group(int cpu)
6097 return first_cpu(cpu_sibling_map[cpu]);
6099 #elif defined(CONFIG_SCHED_MC)
6100 static int cpu_to_core_group(int cpu)
6102 return cpu;
6104 #endif
6106 static DEFINE_PER_CPU(struct sched_domain, phys_domains);
6107 static struct sched_group *sched_group_phys_bycpu[NR_CPUS];
6109 static int cpu_to_phys_group(int cpu)
6111 #ifdef CONFIG_SCHED_MC
6112 cpumask_t mask = cpu_coregroup_map(cpu);
6113 return first_cpu(mask);
6114 #elif defined(CONFIG_SCHED_SMT)
6115 return first_cpu(cpu_sibling_map[cpu]);
6116 #else
6117 return cpu;
6118 #endif
6121 #ifdef CONFIG_NUMA
6122 /*
6123 * The init_sched_build_groups can't handle what we want to do with node
6124 * groups, so roll our own. Now each node has its own list of groups which
6125 * gets dynamically allocated.
6126 */
6127 static DEFINE_PER_CPU(struct sched_domain, node_domains);
6128 static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
6130 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
6131 static struct sched_group *sched_group_allnodes_bycpu[NR_CPUS];
6133 static int cpu_to_allnodes_group(int cpu)
6135 return cpu_to_node(cpu);
6137 static void init_numa_sched_groups_power(struct sched_group *group_head)
6139 struct sched_group *sg = group_head;
6140 int j;
6142 if (!sg)
6143 return;
6144 next_sg:
6145 for_each_cpu_mask(j, sg->cpumask) {
6146 struct sched_domain *sd;
6148 sd = &per_cpu(phys_domains, j);
6149 if (j != first_cpu(sd->groups->cpumask)) {
6150 /*
6151 * Only add "power" once for each
6152 * physical package.
6153 */
6154 continue;
6157 sg->cpu_power += sd->groups->cpu_power;
6159 sg = sg->next;
6160 if (sg != group_head)
6161 goto next_sg;
6163 #endif
6165 /* Free memory allocated for various sched_group structures */
6166 static void free_sched_groups(const cpumask_t *cpu_map)
6168 int cpu;
6169 #ifdef CONFIG_NUMA
6170 int i;
6172 for_each_cpu_mask(cpu, *cpu_map) {
6173 struct sched_group *sched_group_allnodes
6174 = sched_group_allnodes_bycpu[cpu];
6175 struct sched_group **sched_group_nodes
6176 = sched_group_nodes_bycpu[cpu];
6178 if (sched_group_allnodes) {
6179 kfree(sched_group_allnodes);
6180 sched_group_allnodes_bycpu[cpu] = NULL;
6183 if (!sched_group_nodes)
6184 continue;
6186 for (i = 0; i < MAX_NUMNODES; i++) {
6187 cpumask_t nodemask = node_to_cpumask(i);
6188 struct sched_group *oldsg, *sg = sched_group_nodes[i];
6190 cpus_and(nodemask, nodemask, *cpu_map);
6191 if (cpus_empty(nodemask))
6192 continue;
6194 if (sg == NULL)
6195 continue;
6196 sg = sg->next;
6197 next_sg:
6198 oldsg = sg;
6199 sg = sg->next;
6200 kfree(oldsg);
6201 if (oldsg != sched_group_nodes[i])
6202 goto next_sg;
6204 kfree(sched_group_nodes);
6205 sched_group_nodes_bycpu[cpu] = NULL;
6207 #endif
6208 for_each_cpu_mask(cpu, *cpu_map) {
6209 if (sched_group_phys_bycpu[cpu]) {
6210 kfree(sched_group_phys_bycpu[cpu]);
6211 sched_group_phys_bycpu[cpu] = NULL;
6213 #ifdef CONFIG_SCHED_MC
6214 if (sched_group_core_bycpu[cpu]) {
6215 kfree(sched_group_core_bycpu[cpu]);
6216 sched_group_core_bycpu[cpu] = NULL;
6218 #endif
6222 /*
6223 * Build sched domains for a given set of cpus and attach the sched domains
6224 * to the individual cpus
6225 */
6226 static int build_sched_domains(const cpumask_t *cpu_map)
6228 int i;
6229 struct sched_group *sched_group_phys = NULL;
6230 #ifdef CONFIG_SCHED_MC
6231 struct sched_group *sched_group_core = NULL;
6232 #endif
6233 #ifdef CONFIG_NUMA
6234 struct sched_group **sched_group_nodes = NULL;
6235 struct sched_group *sched_group_allnodes = NULL;
6237 /*
6238 * Allocate the per-node list of sched groups
6239 */
6240 sched_group_nodes = kzalloc(sizeof(struct sched_group*)*MAX_NUMNODES,
6241 GFP_KERNEL);
6242 if (!sched_group_nodes) {
6243 printk(KERN_WARNING "Can not alloc sched group node list\n");
6244 return -ENOMEM;
6246 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
6247 #endif
6249 /*
6250 * Set up domains for cpus specified by the cpu_map.
6251 */
6252 for_each_cpu_mask(i, *cpu_map) {
6253 int group;
6254 struct sched_domain *sd = NULL, *p;
6255 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
6257 cpus_and(nodemask, nodemask, *cpu_map);
6259 #ifdef CONFIG_NUMA
6260 if (cpus_weight(*cpu_map)
6261 > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
6262 if (!sched_group_allnodes) {
6263 sched_group_allnodes
6264 = kmalloc(sizeof(struct sched_group)
6265 * MAX_NUMNODES,
6266 GFP_KERNEL);
6267 if (!sched_group_allnodes) {
6268 printk(KERN_WARNING
6269 "Can not alloc allnodes sched group\n");
6270 goto error;
6272 sched_group_allnodes_bycpu[i]
6273 = sched_group_allnodes;
6275 sd = &per_cpu(allnodes_domains, i);
6276 *sd = SD_ALLNODES_INIT;
6277 sd->span = *cpu_map;
6278 group = cpu_to_allnodes_group(i);
6279 sd->groups = &sched_group_allnodes[group];
6280 p = sd;
6281 } else
6282 p = NULL;
6284 sd = &per_cpu(node_domains, i);
6285 *sd = SD_NODE_INIT;
6286 sd->span = sched_domain_node_span(cpu_to_node(i));
6287 sd->parent = p;
6288 cpus_and(sd->span, sd->span, *cpu_map);
6289 #endif
6291 if (!sched_group_phys) {
6292 sched_group_phys
6293 = kmalloc(sizeof(struct sched_group) * NR_CPUS,
6294 GFP_KERNEL);
6295 if (!sched_group_phys) {
6296 printk (KERN_WARNING "Can not alloc phys sched"
6297 "group\n");
6298 goto error;
6300 sched_group_phys_bycpu[i] = sched_group_phys;
6303 p = sd;
6304 sd = &per_cpu(phys_domains, i);
6305 group = cpu_to_phys_group(i);
6306 *sd = SD_CPU_INIT;
6307 sd->span = nodemask;
6308 sd->parent = p;
6309 sd->groups = &sched_group_phys[group];
6311 #ifdef CONFIG_SCHED_MC
6312 if (!sched_group_core) {
6313 sched_group_core
6314 = kmalloc(sizeof(struct sched_group) * NR_CPUS,
6315 GFP_KERNEL);
6316 if (!sched_group_core) {
6317 printk (KERN_WARNING "Can not alloc core sched"
6318 "group\n");
6319 goto error;
6321 sched_group_core_bycpu[i] = sched_group_core;
6324 p = sd;
6325 sd = &per_cpu(core_domains, i);
6326 group = cpu_to_core_group(i);
6327 *sd = SD_MC_INIT;
6328 sd->span = cpu_coregroup_map(i);
6329 cpus_and(sd->span, sd->span, *cpu_map);
6330 sd->parent = p;
6331 sd->groups = &sched_group_core[group];
6332 #endif
6334 #ifdef CONFIG_SCHED_SMT
6335 p = sd;
6336 sd = &per_cpu(cpu_domains, i);
6337 group = cpu_to_cpu_group(i);
6338 *sd = SD_SIBLING_INIT;
6339 sd->span = cpu_sibling_map[i];
6340 cpus_and(sd->span, sd->span, *cpu_map);
6341 sd->parent = p;
6342 sd->groups = &sched_group_cpus[group];
6343 #endif
6346 #ifdef CONFIG_SCHED_SMT
6347 /* Set up CPU (sibling) groups */
6348 for_each_cpu_mask(i, *cpu_map) {
6349 cpumask_t this_sibling_map = cpu_sibling_map[i];
6350 cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
6351 if (i != first_cpu(this_sibling_map))
6352 continue;
6354 init_sched_build_groups(sched_group_cpus, this_sibling_map,
6355 &cpu_to_cpu_group);
6357 #endif
6359 #ifdef CONFIG_SCHED_MC
6360 /* Set up multi-core groups */
6361 for_each_cpu_mask(i, *cpu_map) {
6362 cpumask_t this_core_map = cpu_coregroup_map(i);
6363 cpus_and(this_core_map, this_core_map, *cpu_map);
6364 if (i != first_cpu(this_core_map))
6365 continue;
6366 init_sched_build_groups(sched_group_core, this_core_map,
6367 &cpu_to_core_group);
6369 #endif
6372 /* Set up physical groups */
6373 for (i = 0; i < MAX_NUMNODES; i++) {
6374 cpumask_t nodemask = node_to_cpumask(i);
6376 cpus_and(nodemask, nodemask, *cpu_map);
6377 if (cpus_empty(nodemask))
6378 continue;
6380 init_sched_build_groups(sched_group_phys, nodemask,
6381 &cpu_to_phys_group);
6384 #ifdef CONFIG_NUMA
6385 /* Set up node groups */
6386 if (sched_group_allnodes)
6387 init_sched_build_groups(sched_group_allnodes, *cpu_map,
6388 &cpu_to_allnodes_group);
6390 for (i = 0; i < MAX_NUMNODES; i++) {
6391 /* Set up node groups */
6392 struct sched_group *sg, *prev;
6393 cpumask_t nodemask = node_to_cpumask(i);
6394 cpumask_t domainspan;
6395 cpumask_t covered = CPU_MASK_NONE;
6396 int j;
6398 cpus_and(nodemask, nodemask, *cpu_map);
6399 if (cpus_empty(nodemask)) {
6400 sched_group_nodes[i] = NULL;
6401 continue;
6404 domainspan = sched_domain_node_span(i);
6405 cpus_and(domainspan, domainspan, *cpu_map);
6407 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
6408 if (!sg) {
6409 printk(KERN_WARNING "Can not alloc domain group for "
6410 "node %d\n", i);
6411 goto error;
6413 sched_group_nodes[i] = sg;
6414 for_each_cpu_mask(j, nodemask) {
6415 struct sched_domain *sd;
6416 sd = &per_cpu(node_domains, j);
6417 sd->groups = sg;
6419 sg->cpu_power = 0;
6420 sg->cpumask = nodemask;
6421 sg->next = sg;
6422 cpus_or(covered, covered, nodemask);
6423 prev = sg;
6425 for (j = 0; j < MAX_NUMNODES; j++) {
6426 cpumask_t tmp, notcovered;
6427 int n = (i + j) % MAX_NUMNODES;
6429 cpus_complement(notcovered, covered);
6430 cpus_and(tmp, notcovered, *cpu_map);
6431 cpus_and(tmp, tmp, domainspan);
6432 if (cpus_empty(tmp))
6433 break;
6435 nodemask = node_to_cpumask(n);
6436 cpus_and(tmp, tmp, nodemask);
6437 if (cpus_empty(tmp))
6438 continue;
6440 sg = kmalloc_node(sizeof(struct sched_group),
6441 GFP_KERNEL, i);
6442 if (!sg) {
6443 printk(KERN_WARNING
6444 "Can not alloc domain group for node %d\n", j);
6445 goto error;
6447 sg->cpu_power = 0;
6448 sg->cpumask = tmp;
6449 sg->next = prev->next;
6450 cpus_or(covered, covered, tmp);
6451 prev->next = sg;
6452 prev = sg;
6455 #endif
6457 /* Calculate CPU power for physical packages and nodes */
6458 #ifdef CONFIG_SCHED_SMT
6459 for_each_cpu_mask(i, *cpu_map) {
6460 struct sched_domain *sd;
6461 sd = &per_cpu(cpu_domains, i);
6462 sd->groups->cpu_power = SCHED_LOAD_SCALE;
6464 #endif
6465 #ifdef CONFIG_SCHED_MC
6466 for_each_cpu_mask(i, *cpu_map) {
6467 int power;
6468 struct sched_domain *sd;
6469 sd = &per_cpu(core_domains, i);
6470 if (sched_smt_power_savings)
6471 power = SCHED_LOAD_SCALE * cpus_weight(sd->groups->cpumask);
6472 else
6473 power = SCHED_LOAD_SCALE + (cpus_weight(sd->groups->cpumask)-1)
6474 * SCHED_LOAD_SCALE / 10;
6475 sd->groups->cpu_power = power;
6477 #endif
6479 for_each_cpu_mask(i, *cpu_map) {
6480 struct sched_domain *sd;
6481 #ifdef CONFIG_SCHED_MC
6482 sd = &per_cpu(phys_domains, i);
6483 if (i != first_cpu(sd->groups->cpumask))
6484 continue;
6486 sd->groups->cpu_power = 0;
6487 if (sched_mc_power_savings || sched_smt_power_savings) {
6488 int j;
6490 for_each_cpu_mask(j, sd->groups->cpumask) {
6491 struct sched_domain *sd1;
6492 sd1 = &per_cpu(core_domains, j);
6493 /*
6494 * for each core we will add once
6495 * to the group in physical domain
6496 */
6497 if (j != first_cpu(sd1->groups->cpumask))
6498 continue;
6500 if (sched_smt_power_savings)
6501 sd->groups->cpu_power += sd1->groups->cpu_power;
6502 else
6503 sd->groups->cpu_power += SCHED_LOAD_SCALE;
6505 } else
6506 /*
6507 * This has to be < 2 * SCHED_LOAD_SCALE
6508 * Lets keep it SCHED_LOAD_SCALE, so that
6509 * while calculating NUMA group's cpu_power
6510 * we can simply do
6511 * numa_group->cpu_power += phys_group->cpu_power;
6513 * See "only add power once for each physical pkg"
6514 * comment below
6515 */
6516 sd->groups->cpu_power = SCHED_LOAD_SCALE;
6517 #else
6518 int power;
6519 sd = &per_cpu(phys_domains, i);
6520 if (sched_smt_power_savings)
6521 power = SCHED_LOAD_SCALE * cpus_weight(sd->groups->cpumask);
6522 else
6523 power = SCHED_LOAD_SCALE;
6524 sd->groups->cpu_power = power;
6525 #endif
6528 #ifdef CONFIG_NUMA
6529 for (i = 0; i < MAX_NUMNODES; i++)
6530 init_numa_sched_groups_power(sched_group_nodes[i]);
6532 if (sched_group_allnodes) {
6533 int group = cpu_to_allnodes_group(first_cpu(*cpu_map));
6534 struct sched_group *sg = &sched_group_allnodes[group];
6536 init_numa_sched_groups_power(sg);
6538 #endif
6540 /* Attach the domains */
6541 for_each_cpu_mask(i, *cpu_map) {
6542 struct sched_domain *sd;
6543 #ifdef CONFIG_SCHED_SMT
6544 sd = &per_cpu(cpu_domains, i);
6545 #elif defined(CONFIG_SCHED_MC)
6546 sd = &per_cpu(core_domains, i);
6547 #else
6548 sd = &per_cpu(phys_domains, i);
6549 #endif
6550 cpu_attach_domain(sd, i);
6552 /*
6553 * Tune cache-hot values:
6554 */
6555 calibrate_migration_costs(cpu_map);
6557 return 0;
6559 error:
6560 free_sched_groups(cpu_map);
6561 return -ENOMEM;
6563 /*
6564 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6565 */
6566 static int arch_init_sched_domains(const cpumask_t *cpu_map)
6568 cpumask_t cpu_default_map;
6569 int err;
6571 /*
6572 * Setup mask for cpus without special case scheduling requirements.
6573 * For now this just excludes isolated cpus, but could be used to
6574 * exclude other special cases in the future.
6575 */
6576 cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
6578 err = build_sched_domains(&cpu_default_map);
6580 return err;
6583 static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
6585 free_sched_groups(cpu_map);
6588 /*
6589 * Detach sched domains from a group of cpus specified in cpu_map
6590 * These cpus will now be attached to the NULL domain
6591 */
6592 static void detach_destroy_domains(const cpumask_t *cpu_map)
6594 int i;
6596 for_each_cpu_mask(i, *cpu_map)
6597 cpu_attach_domain(NULL, i);
6598 synchronize_sched();
6599 arch_destroy_sched_domains(cpu_map);
6602 /*
6603 * Partition sched domains as specified by the cpumasks below.
6604 * This attaches all cpus from the cpumasks to the NULL domain,
6605 * waits for a RCU quiescent period, recalculates sched
6606 * domain information and then attaches them back to the
6607 * correct sched domains
6608 * Call with hotplug lock held
6609 */
6610 int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
6612 cpumask_t change_map;
6613 int err = 0;
6615 cpus_and(*partition1, *partition1, cpu_online_map);
6616 cpus_and(*partition2, *partition2, cpu_online_map);
6617 cpus_or(change_map, *partition1, *partition2);
6619 /* Detach sched domains from all of the affected cpus */
6620 detach_destroy_domains(&change_map);
6621 if (!cpus_empty(*partition1))
6622 err = build_sched_domains(partition1);
6623 if (!err && !cpus_empty(*partition2))
6624 err = build_sched_domains(partition2);
6626 return err;
6629 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6630 int arch_reinit_sched_domains(void)
6632 int err;
6634 lock_cpu_hotplug();
6635 detach_destroy_domains(&cpu_online_map);
6636 err = arch_init_sched_domains(&cpu_online_map);
6637 unlock_cpu_hotplug();
6639 return err;
6642 static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
6644 int ret;
6646 if (buf[0] != '0' && buf[0] != '1')
6647 return -EINVAL;
6649 if (smt)
6650 sched_smt_power_savings = (buf[0] == '1');
6651 else
6652 sched_mc_power_savings = (buf[0] == '1');
6654 ret = arch_reinit_sched_domains();
6656 return ret ? ret : count;
6659 int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
6661 int err = 0;
6663 #ifdef CONFIG_SCHED_SMT
6664 if (smt_capable())
6665 err = sysfs_create_file(&cls->kset.kobj,
6666 &attr_sched_smt_power_savings.attr);
6667 #endif
6668 #ifdef CONFIG_SCHED_MC
6669 if (!err && mc_capable())
6670 err = sysfs_create_file(&cls->kset.kobj,
6671 &attr_sched_mc_power_savings.attr);
6672 #endif
6673 return err;
6675 #endif
6677 #ifdef CONFIG_SCHED_MC
6678 static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
6680 return sprintf(page, "%u\n", sched_mc_power_savings);
6682 static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
6683 const char *buf, size_t count)
6685 return sched_power_savings_store(buf, count, 0);
6687 SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
6688 sched_mc_power_savings_store);
6689 #endif
6691 #ifdef CONFIG_SCHED_SMT
6692 static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
6694 return sprintf(page, "%u\n", sched_smt_power_savings);
6696 static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
6697 const char *buf, size_t count)
6699 return sched_power_savings_store(buf, count, 1);
6701 SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
6702 sched_smt_power_savings_store);
6703 #endif
6706 #ifdef CONFIG_HOTPLUG_CPU
6707 /*
6708 * Force a reinitialization of the sched domains hierarchy. The domains
6709 * and groups cannot be updated in place without racing with the balancing
6710 * code, so we temporarily attach all running cpus to the NULL domain
6711 * which will prevent rebalancing while the sched domains are recalculated.
6712 */
6713 static int update_sched_domains(struct notifier_block *nfb,
6714 unsigned long action, void *hcpu)
6716 switch (action) {
6717 case CPU_UP_PREPARE:
6718 case CPU_DOWN_PREPARE:
6719 detach_destroy_domains(&cpu_online_map);
6720 return NOTIFY_OK;
6722 case CPU_UP_CANCELED:
6723 case CPU_DOWN_FAILED:
6724 case CPU_ONLINE:
6725 case CPU_DEAD:
6726 /*
6727 * Fall through and re-initialise the domains.
6728 */
6729 break;
6730 default:
6731 return NOTIFY_DONE;
6734 /* The hotplug lock is already held by cpu_up/cpu_down */
6735 arch_init_sched_domains(&cpu_online_map);
6737 return NOTIFY_OK;
6739 #endif
6741 void __init sched_init_smp(void)
6743 lock_cpu_hotplug();
6744 arch_init_sched_domains(&cpu_online_map);
6745 unlock_cpu_hotplug();
6746 /* XXX: Theoretical race here - CPU may be hotplugged now */
6747 hotcpu_notifier(update_sched_domains, 0);
6749 #else
6750 void __init sched_init_smp(void)
6753 #endif /* CONFIG_SMP */
6755 int in_sched_functions(unsigned long addr)
6757 /* Linker adds these: start and end of __sched functions */
6758 extern char __sched_text_start[], __sched_text_end[];
6760 return in_lock_functions(addr) ||
6761 (addr >= (unsigned long)__sched_text_start
6762 && addr < (unsigned long)__sched_text_end);
6765 void __init sched_init(void)
6767 int i, j, k;
6769 for_each_possible_cpu(i) {
6770 struct prio_array *array;
6771 struct rq *rq;
6773 rq = cpu_rq(i);
6774 spin_lock_init(&rq->lock);
6775 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
6776 rq->nr_running = 0;
6777 rq->active = rq->arrays;
6778 rq->expired = rq->arrays + 1;
6779 rq->best_expired_prio = MAX_PRIO;
6781 #ifdef CONFIG_SMP
6782 rq->sd = NULL;
6783 for (j = 1; j < 3; j++)
6784 rq->cpu_load[j] = 0;
6785 rq->active_balance = 0;
6786 rq->push_cpu = 0;
6787 rq->cpu = i;
6788 rq->migration_thread = NULL;
6789 INIT_LIST_HEAD(&rq->migration_queue);
6790 #endif
6791 atomic_set(&rq->nr_iowait, 0);
6793 for (j = 0; j < 2; j++) {
6794 array = rq->arrays + j;
6795 for (k = 0; k < MAX_PRIO; k++) {
6796 INIT_LIST_HEAD(array->queue + k);
6797 __clear_bit(k, array->bitmap);
6799 // delimiter for bitsearch
6800 __set_bit(MAX_PRIO, array->bitmap);
6804 set_load_weight(&init_task);
6806 #ifdef CONFIG_RT_MUTEXES
6807 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
6808 #endif
6810 /*
6811 * The boot idle thread does lazy MMU switching as well:
6812 */
6813 atomic_inc(&init_mm.mm_count);
6814 enter_lazy_tlb(&init_mm, current);
6816 /*
6817 * Make us the idle thread. Technically, schedule() should not be
6818 * called from this thread, however somewhere below it might be,
6819 * but because we are the idle thread, we just pick up running again
6820 * when this runqueue becomes "idle".
6821 */
6822 init_idle(current, smp_processor_id());
6825 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6826 void __might_sleep(char *file, int line)
6828 #ifdef in_atomic
6829 static unsigned long prev_jiffy; /* ratelimiting */
6831 if ((in_atomic() || irqs_disabled()) &&
6832 system_state == SYSTEM_RUNNING && !oops_in_progress) {
6833 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6834 return;
6835 prev_jiffy = jiffies;
6836 printk(KERN_ERR "BUG: sleeping function called from invalid"
6837 " context at %s:%d\n", file, line);
6838 printk("in_atomic():%d, irqs_disabled():%d\n",
6839 in_atomic(), irqs_disabled());
6840 dump_stack();
6842 #endif
6844 EXPORT_SYMBOL(__might_sleep);
6845 #endif
6847 #ifdef CONFIG_MAGIC_SYSRQ
6848 void normalize_rt_tasks(void)
6850 struct prio_array *array;
6851 struct task_struct *p;
6852 unsigned long flags;
6853 struct rq *rq;
6855 read_lock_irq(&tasklist_lock);
6856 for_each_process(p) {
6857 if (!rt_task(p))
6858 continue;
6860 spin_lock_irqsave(&p->pi_lock, flags);
6861 rq = __task_rq_lock(p);
6863 array = p->array;
6864 if (array)
6865 deactivate_task(p, task_rq(p));
6866 __setscheduler(p, SCHED_NORMAL, 0);
6867 if (array) {
6868 __activate_task(p, task_rq(p));
6869 resched_task(rq->curr);
6872 __task_rq_unlock(rq);
6873 spin_unlock_irqrestore(&p->pi_lock, flags);
6875 read_unlock_irq(&tasklist_lock);
6878 #endif /* CONFIG_MAGIC_SYSRQ */
6880 #ifdef CONFIG_IA64
6881 /*
6882 * These functions are only useful for the IA64 MCA handling.
6884 * They can only be called when the whole system has been
6885 * stopped - every CPU needs to be quiescent, and no scheduling
6886 * activity can take place. Using them for anything else would
6887 * be a serious bug, and as a result, they aren't even visible
6888 * under any other configuration.
6889 */
6891 /**
6892 * curr_task - return the current task for a given cpu.
6893 * @cpu: the processor in question.
6895 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6896 */
6897 struct task_struct *curr_task(int cpu)
6899 return cpu_curr(cpu);
6902 /**
6903 * set_curr_task - set the current task for a given cpu.
6904 * @cpu: the processor in question.
6905 * @p: the task pointer to set.
6907 * Description: This function must only be used when non-maskable interrupts
6908 * are serviced on a separate stack. It allows the architecture to switch the
6909 * notion of the current task on a cpu in a non-blocking manner. This function
6910 * must be called with all CPU's synchronized, and interrupts disabled, the
6911 * and caller must save the original value of the current task (see
6912 * curr_task() above) and restore that value before reenabling interrupts and
6913 * re-starting the system.
6915 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6916 */
6917 void set_curr_task(int cpu, struct task_struct *p)
6919 cpu_curr(cpu) = p;
6922 #endif