Add apply_to_page_range() which applies a function to a pte range
[linux-2.6-block.git] / kernel / sched.c
CommitLineData
1da177e4
LT
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 */
20
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>
c59ede7b 30#include <linux/capability.h>
1da177e4
LT
31#include <linux/completion.h>
32#include <linux/kernel_stat.h>
9a11b49a 33#include <linux/debug_locks.h>
1da177e4
LT
34#include <linux/security.h>
35#include <linux/notifier.h>
36#include <linux/profile.h>
7dfb7103 37#include <linux/freezer.h>
198e2f18 38#include <linux/vmalloc.h>
1da177e4
LT
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>
8f0ab514 52#include <linux/tsacct_kern.h>
c6fd91f0 53#include <linux/kprobes.h>
0ff92245 54#include <linux/delayacct.h>
1da177e4
LT
55#include <asm/tlb.h>
56
57#include <asm/unistd.h>
58
b035b6de
AD
59/*
60 * Scheduler clock - returns current time in nanosec units.
61 * This is default implementation.
62 * Architectures and sub-architectures can override this.
63 */
64unsigned long long __attribute__((weak)) sched_clock(void)
65{
66 return (unsigned long long)jiffies * (1000000000 / HZ);
67}
68
1da177e4
LT
69/*
70 * Convert user-nice values [ -20 ... 0 ... 19 ]
71 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
72 * and back.
73 */
74#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
75#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
76#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
77
78/*
79 * 'User priority' is the nice value converted to something we
80 * can work with better when scaling various scheduler parameters,
81 * it's a [ 0 ... 39 ] range.
82 */
83#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
84#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
85#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
86
87/*
88 * Some helpers for converting nanosecond timing to jiffy resolution
89 */
90#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
91#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
92
93/*
94 * These are the 'tuning knobs' of the scheduler:
95 *
96 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
97 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
98 * Timeslices get refilled after they expire.
99 */
100#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
101#define DEF_TIMESLICE (100 * HZ / 1000)
102#define ON_RUNQUEUE_WEIGHT 30
103#define CHILD_PENALTY 95
104#define PARENT_PENALTY 100
105#define EXIT_WEIGHT 3
106#define PRIO_BONUS_RATIO 25
107#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
108#define INTERACTIVE_DELTA 2
109#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
110#define STARVATION_LIMIT (MAX_SLEEP_AVG)
111#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
112
113/*
114 * If a task is 'interactive' then we reinsert it in the active
115 * array after it has expired its current timeslice. (it will not
116 * continue to run immediately, it will still roundrobin with
117 * other interactive tasks.)
118 *
119 * This part scales the interactivity limit depending on niceness.
120 *
121 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
122 * Here are a few examples of different nice levels:
123 *
124 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
125 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
126 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
127 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
128 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
129 *
130 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
131 * priority range a task can explore, a value of '1' means the
132 * task is rated interactive.)
133 *
134 * Ie. nice +19 tasks can never get 'interactive' enough to be
135 * reinserted into the active array. And only heavily CPU-hog nice -20
136 * tasks will be expired. Default nice 0 tasks are somewhere between,
137 * it takes some effort for them to get interactive, but it's not
138 * too hard.
139 */
140
141#define CURRENT_BONUS(p) \
142 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
143 MAX_SLEEP_AVG)
144
145#define GRANULARITY (10 * HZ / 1000 ? : 1)
146
147#ifdef CONFIG_SMP
148#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
149 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
150 num_online_cpus())
151#else
152#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
153 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
154#endif
155
156#define SCALE(v1,v1_max,v2_max) \
157 (v1) * (v2_max) / (v1_max)
158
159#define DELTA(p) \
013d3868
MA
160 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
161 INTERACTIVE_DELTA)
1da177e4
LT
162
163#define TASK_INTERACTIVE(p) \
164 ((p)->prio <= (p)->static_prio - DELTA(p))
165
166#define INTERACTIVE_SLEEP(p) \
167 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
168 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
169
170#define TASK_PREEMPTS_CURR(p, rq) \
171 ((p)->prio < (rq)->curr->prio)
172
1da177e4 173#define SCALE_PRIO(x, prio) \
2dd73a4f 174 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
1da177e4 175
2dd73a4f 176static unsigned int static_prio_timeslice(int static_prio)
1da177e4 177{
2dd73a4f
PW
178 if (static_prio < NICE_TO_PRIO(0))
179 return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
1da177e4 180 else
2dd73a4f 181 return SCALE_PRIO(DEF_TIMESLICE, static_prio);
1da177e4 182}
2dd73a4f 183
91fcdd4e
BP
184/*
185 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
186 * to time slice values: [800ms ... 100ms ... 5ms]
187 *
188 * The higher a thread's priority, the bigger timeslices
189 * it gets during one round of execution. But even the lowest
190 * priority thread gets MIN_TIMESLICE worth of execution time.
191 */
192
36c8b586 193static inline unsigned int task_timeslice(struct task_struct *p)
2dd73a4f
PW
194{
195 return static_prio_timeslice(p->static_prio);
196}
197
1da177e4
LT
198/*
199 * These are the runqueue data structures:
200 */
201
1da177e4
LT
202struct prio_array {
203 unsigned int nr_active;
d444886e 204 DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */
1da177e4
LT
205 struct list_head queue[MAX_PRIO];
206};
207
208/*
209 * This is the main, per-CPU runqueue data structure.
210 *
211 * Locking rule: those places that want to lock multiple runqueues
212 * (such as the load balancing or the thread migration code), lock
213 * acquire operations must be ordered by ascending &runqueue.
214 */
70b97a7f 215struct rq {
1da177e4
LT
216 spinlock_t lock;
217
218 /*
219 * nr_running and cpu_load should be in the same cacheline because
220 * remote CPUs use both these fields when doing load calculation.
221 */
222 unsigned long nr_running;
2dd73a4f 223 unsigned long raw_weighted_load;
1da177e4 224#ifdef CONFIG_SMP
7897986b 225 unsigned long cpu_load[3];
1da177e4
LT
226#endif
227 unsigned long long nr_switches;
228
229 /*
230 * This is part of a global counter where only the total sum
231 * over all CPUs matters. A task can increase this counter on
232 * one CPU and if it got migrated afterwards it may decrease
233 * it on another CPU. Always updated under the runqueue lock:
234 */
235 unsigned long nr_uninterruptible;
236
237 unsigned long expired_timestamp;
b18ec803
MG
238 /* Cached timestamp set by update_cpu_clock() */
239 unsigned long long most_recent_timestamp;
36c8b586 240 struct task_struct *curr, *idle;
c9819f45 241 unsigned long next_balance;
1da177e4 242 struct mm_struct *prev_mm;
70b97a7f 243 struct prio_array *active, *expired, arrays[2];
1da177e4
LT
244 int best_expired_prio;
245 atomic_t nr_iowait;
246
247#ifdef CONFIG_SMP
248 struct sched_domain *sd;
249
250 /* For active balancing */
251 int active_balance;
252 int push_cpu;
0a2966b4 253 int cpu; /* cpu of this runqueue */
1da177e4 254
36c8b586 255 struct task_struct *migration_thread;
1da177e4
LT
256 struct list_head migration_queue;
257#endif
258
259#ifdef CONFIG_SCHEDSTATS
260 /* latency stats */
261 struct sched_info rq_sched_info;
262
263 /* sys_sched_yield() stats */
264 unsigned long yld_exp_empty;
265 unsigned long yld_act_empty;
266 unsigned long yld_both_empty;
267 unsigned long yld_cnt;
268
269 /* schedule() stats */
270 unsigned long sched_switch;
271 unsigned long sched_cnt;
272 unsigned long sched_goidle;
273
274 /* try_to_wake_up() stats */
275 unsigned long ttwu_cnt;
276 unsigned long ttwu_local;
277#endif
fcb99371 278 struct lock_class_key rq_lock_key;
1da177e4
LT
279};
280
70b97a7f 281static DEFINE_PER_CPU(struct rq, runqueues);
1da177e4 282
0a2966b4
CL
283static inline int cpu_of(struct rq *rq)
284{
285#ifdef CONFIG_SMP
286 return rq->cpu;
287#else
288 return 0;
289#endif
290}
291
674311d5
NP
292/*
293 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
1a20ff27 294 * See detach_destroy_domains: synchronize_sched for details.
674311d5
NP
295 *
296 * The domain tree of any CPU may only be accessed from within
297 * preempt-disabled sections.
298 */
48f24c4d
IM
299#define for_each_domain(cpu, __sd) \
300 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
1da177e4
LT
301
302#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
303#define this_rq() (&__get_cpu_var(runqueues))
304#define task_rq(p) cpu_rq(task_cpu(p))
305#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
306
1da177e4 307#ifndef prepare_arch_switch
4866cde0
NP
308# define prepare_arch_switch(next) do { } while (0)
309#endif
310#ifndef finish_arch_switch
311# define finish_arch_switch(prev) do { } while (0)
312#endif
313
314#ifndef __ARCH_WANT_UNLOCKED_CTXSW
70b97a7f 315static inline int task_running(struct rq *rq, struct task_struct *p)
4866cde0
NP
316{
317 return rq->curr == p;
318}
319
70b97a7f 320static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
4866cde0
NP
321{
322}
323
70b97a7f 324static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
4866cde0 325{
da04c035
IM
326#ifdef CONFIG_DEBUG_SPINLOCK
327 /* this is a valid case when another task releases the spinlock */
328 rq->lock.owner = current;
329#endif
8a25d5de
IM
330 /*
331 * If we are tracking spinlock dependencies then we have to
332 * fix up the runqueue lock - which gets 'carried over' from
333 * prev into current:
334 */
335 spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
336
4866cde0
NP
337 spin_unlock_irq(&rq->lock);
338}
339
340#else /* __ARCH_WANT_UNLOCKED_CTXSW */
70b97a7f 341static inline int task_running(struct rq *rq, struct task_struct *p)
4866cde0
NP
342{
343#ifdef CONFIG_SMP
344 return p->oncpu;
345#else
346 return rq->curr == p;
347#endif
348}
349
70b97a7f 350static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
4866cde0
NP
351{
352#ifdef CONFIG_SMP
353 /*
354 * We can optimise this out completely for !SMP, because the
355 * SMP rebalancing from interrupt is the only thing that cares
356 * here.
357 */
358 next->oncpu = 1;
359#endif
360#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
361 spin_unlock_irq(&rq->lock);
362#else
363 spin_unlock(&rq->lock);
364#endif
365}
366
70b97a7f 367static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
4866cde0
NP
368{
369#ifdef CONFIG_SMP
370 /*
371 * After ->oncpu is cleared, the task can be moved to a different CPU.
372 * We must ensure this doesn't happen until the switch is completely
373 * finished.
374 */
375 smp_wmb();
376 prev->oncpu = 0;
377#endif
378#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
379 local_irq_enable();
1da177e4 380#endif
4866cde0
NP
381}
382#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
1da177e4 383
b29739f9
IM
384/*
385 * __task_rq_lock - lock the runqueue a given task resides on.
386 * Must be called interrupts disabled.
387 */
70b97a7f 388static inline struct rq *__task_rq_lock(struct task_struct *p)
b29739f9
IM
389 __acquires(rq->lock)
390{
70b97a7f 391 struct rq *rq;
b29739f9
IM
392
393repeat_lock_task:
394 rq = task_rq(p);
395 spin_lock(&rq->lock);
396 if (unlikely(rq != task_rq(p))) {
397 spin_unlock(&rq->lock);
398 goto repeat_lock_task;
399 }
400 return rq;
401}
402
1da177e4
LT
403/*
404 * task_rq_lock - lock the runqueue a given task resides on and disable
405 * interrupts. Note the ordering: we can safely lookup the task_rq without
406 * explicitly disabling preemption.
407 */
70b97a7f 408static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
1da177e4
LT
409 __acquires(rq->lock)
410{
70b97a7f 411 struct rq *rq;
1da177e4
LT
412
413repeat_lock_task:
414 local_irq_save(*flags);
415 rq = task_rq(p);
416 spin_lock(&rq->lock);
417 if (unlikely(rq != task_rq(p))) {
418 spin_unlock_irqrestore(&rq->lock, *flags);
419 goto repeat_lock_task;
420 }
421 return rq;
422}
423
70b97a7f 424static inline void __task_rq_unlock(struct rq *rq)
b29739f9
IM
425 __releases(rq->lock)
426{
427 spin_unlock(&rq->lock);
428}
429
70b97a7f 430static inline void task_rq_unlock(struct rq *rq, unsigned long *flags)
1da177e4
LT
431 __releases(rq->lock)
432{
433 spin_unlock_irqrestore(&rq->lock, *flags);
434}
435
436#ifdef CONFIG_SCHEDSTATS
437/*
438 * bump this up when changing the output format or the meaning of an existing
439 * format, so that tools can adapt (or abort)
440 */
06066714 441#define SCHEDSTAT_VERSION 14
1da177e4
LT
442
443static int show_schedstat(struct seq_file *seq, void *v)
444{
445 int cpu;
446
447 seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
448 seq_printf(seq, "timestamp %lu\n", jiffies);
449 for_each_online_cpu(cpu) {
70b97a7f 450 struct rq *rq = cpu_rq(cpu);
1da177e4
LT
451#ifdef CONFIG_SMP
452 struct sched_domain *sd;
453 int dcnt = 0;
454#endif
455
456 /* runqueue-specific stats */
457 seq_printf(seq,
458 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
459 cpu, rq->yld_both_empty,
460 rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
461 rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
462 rq->ttwu_cnt, rq->ttwu_local,
463 rq->rq_sched_info.cpu_time,
464 rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
465
466 seq_printf(seq, "\n");
467
468#ifdef CONFIG_SMP
469 /* domain-specific stats */
674311d5 470 preempt_disable();
1da177e4
LT
471 for_each_domain(cpu, sd) {
472 enum idle_type itype;
473 char mask_str[NR_CPUS];
474
475 cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
476 seq_printf(seq, "domain%d %s", dcnt++, mask_str);
477 for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
478 itype++) {
33859f7f
MOS
479 seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu "
480 "%lu",
1da177e4
LT
481 sd->lb_cnt[itype],
482 sd->lb_balanced[itype],
483 sd->lb_failed[itype],
484 sd->lb_imbalance[itype],
485 sd->lb_gained[itype],
486 sd->lb_hot_gained[itype],
487 sd->lb_nobusyq[itype],
06066714 488 sd->lb_nobusyg[itype]);
1da177e4 489 }
33859f7f
MOS
490 seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu"
491 " %lu %lu %lu\n",
1da177e4 492 sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
68767a0a
NP
493 sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
494 sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
33859f7f
MOS
495 sd->ttwu_wake_remote, sd->ttwu_move_affine,
496 sd->ttwu_move_balance);
1da177e4 497 }
674311d5 498 preempt_enable();
1da177e4
LT
499#endif
500 }
501 return 0;
502}
503
504static int schedstat_open(struct inode *inode, struct file *file)
505{
506 unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
507 char *buf = kmalloc(size, GFP_KERNEL);
508 struct seq_file *m;
509 int res;
510
511 if (!buf)
512 return -ENOMEM;
513 res = single_open(file, show_schedstat, NULL);
514 if (!res) {
515 m = file->private_data;
516 m->buf = buf;
517 m->size = size;
518 } else
519 kfree(buf);
520 return res;
521}
522
15ad7cdc 523const struct file_operations proc_schedstat_operations = {
1da177e4
LT
524 .open = schedstat_open,
525 .read = seq_read,
526 .llseek = seq_lseek,
527 .release = single_release,
528};
529
52f17b6c
CS
530/*
531 * Expects runqueue lock to be held for atomicity of update
532 */
533static inline void
534rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
535{
536 if (rq) {
537 rq->rq_sched_info.run_delay += delta_jiffies;
538 rq->rq_sched_info.pcnt++;
539 }
540}
541
542/*
543 * Expects runqueue lock to be held for atomicity of update
544 */
545static inline void
546rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
547{
548 if (rq)
549 rq->rq_sched_info.cpu_time += delta_jiffies;
550}
1da177e4
LT
551# define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
552# define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
553#else /* !CONFIG_SCHEDSTATS */
52f17b6c
CS
554static inline void
555rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies)
556{}
557static inline void
558rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies)
559{}
1da177e4
LT
560# define schedstat_inc(rq, field) do { } while (0)
561# define schedstat_add(rq, field, amt) do { } while (0)
562#endif
563
564/*
cc2a73b5 565 * this_rq_lock - lock this runqueue and disable interrupts.
1da177e4 566 */
70b97a7f 567static inline struct rq *this_rq_lock(void)
1da177e4
LT
568 __acquires(rq->lock)
569{
70b97a7f 570 struct rq *rq;
1da177e4
LT
571
572 local_irq_disable();
573 rq = this_rq();
574 spin_lock(&rq->lock);
575
576 return rq;
577}
578
52f17b6c 579#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1da177e4
LT
580/*
581 * Called when a process is dequeued from the active array and given
582 * the cpu. We should note that with the exception of interactive
583 * tasks, the expired queue will become the active queue after the active
584 * queue is empty, without explicitly dequeuing and requeuing tasks in the
585 * expired queue. (Interactive tasks may be requeued directly to the
586 * active queue, thus delaying tasks in the expired queue from running;
587 * see scheduler_tick()).
588 *
589 * This function is only called from sched_info_arrive(), rather than
590 * dequeue_task(). Even though a task may be queued and dequeued multiple
591 * times as it is shuffled about, we're really interested in knowing how
592 * long it was from the *first* time it was queued to the time that it
593 * finally hit a cpu.
594 */
36c8b586 595static inline void sched_info_dequeued(struct task_struct *t)
1da177e4
LT
596{
597 t->sched_info.last_queued = 0;
598}
599
600/*
601 * Called when a task finally hits the cpu. We can now calculate how
602 * long it was waiting to run. We also note when it began so that we
603 * can keep stats on how long its timeslice is.
604 */
36c8b586 605static void sched_info_arrive(struct task_struct *t)
1da177e4 606{
52f17b6c 607 unsigned long now = jiffies, delta_jiffies = 0;
1da177e4
LT
608
609 if (t->sched_info.last_queued)
52f17b6c 610 delta_jiffies = now - t->sched_info.last_queued;
1da177e4 611 sched_info_dequeued(t);
52f17b6c 612 t->sched_info.run_delay += delta_jiffies;
1da177e4
LT
613 t->sched_info.last_arrival = now;
614 t->sched_info.pcnt++;
615
52f17b6c 616 rq_sched_info_arrive(task_rq(t), delta_jiffies);
1da177e4
LT
617}
618
619/*
620 * Called when a process is queued into either the active or expired
621 * array. The time is noted and later used to determine how long we
622 * had to wait for us to reach the cpu. Since the expired queue will
623 * become the active queue after active queue is empty, without dequeuing
624 * and requeuing any tasks, we are interested in queuing to either. It
625 * is unusual but not impossible for tasks to be dequeued and immediately
626 * requeued in the same or another array: this can happen in sched_yield(),
627 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
628 * to runqueue.
629 *
630 * This function is only called from enqueue_task(), but also only updates
631 * the timestamp if it is already not set. It's assumed that
632 * sched_info_dequeued() will clear that stamp when appropriate.
633 */
36c8b586 634static inline void sched_info_queued(struct task_struct *t)
1da177e4 635{
52f17b6c
CS
636 if (unlikely(sched_info_on()))
637 if (!t->sched_info.last_queued)
638 t->sched_info.last_queued = jiffies;
1da177e4
LT
639}
640
641/*
642 * Called when a process ceases being the active-running process, either
643 * voluntarily or involuntarily. Now we can calculate how long we ran.
644 */
36c8b586 645static inline void sched_info_depart(struct task_struct *t)
1da177e4 646{
52f17b6c 647 unsigned long delta_jiffies = jiffies - t->sched_info.last_arrival;
1da177e4 648
52f17b6c
CS
649 t->sched_info.cpu_time += delta_jiffies;
650 rq_sched_info_depart(task_rq(t), delta_jiffies);
1da177e4
LT
651}
652
653/*
654 * Called when tasks are switched involuntarily due, typically, to expiring
655 * their time slice. (This may also be called when switching to or from
656 * the idle task.) We are only called when prev != next.
657 */
36c8b586 658static inline void
52f17b6c 659__sched_info_switch(struct task_struct *prev, struct task_struct *next)
1da177e4 660{
70b97a7f 661 struct rq *rq = task_rq(prev);
1da177e4
LT
662
663 /*
664 * prev now departs the cpu. It's not interesting to record
665 * stats about how efficient we were at scheduling the idle
666 * process, however.
667 */
668 if (prev != rq->idle)
669 sched_info_depart(prev);
670
671 if (next != rq->idle)
672 sched_info_arrive(next);
673}
52f17b6c
CS
674static inline void
675sched_info_switch(struct task_struct *prev, struct task_struct *next)
676{
677 if (unlikely(sched_info_on()))
678 __sched_info_switch(prev, next);
679}
1da177e4
LT
680#else
681#define sched_info_queued(t) do { } while (0)
682#define sched_info_switch(t, next) do { } while (0)
52f17b6c 683#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
1da177e4
LT
684
685/*
686 * Adding/removing a task to/from a priority array:
687 */
70b97a7f 688static void dequeue_task(struct task_struct *p, struct prio_array *array)
1da177e4
LT
689{
690 array->nr_active--;
691 list_del(&p->run_list);
692 if (list_empty(array->queue + p->prio))
693 __clear_bit(p->prio, array->bitmap);
694}
695
70b97a7f 696static void enqueue_task(struct task_struct *p, struct prio_array *array)
1da177e4
LT
697{
698 sched_info_queued(p);
699 list_add_tail(&p->run_list, array->queue + p->prio);
700 __set_bit(p->prio, array->bitmap);
701 array->nr_active++;
702 p->array = array;
703}
704
705/*
706 * Put task to the end of the run list without the overhead of dequeue
707 * followed by enqueue.
708 */
70b97a7f 709static void requeue_task(struct task_struct *p, struct prio_array *array)
1da177e4
LT
710{
711 list_move_tail(&p->run_list, array->queue + p->prio);
712}
713
70b97a7f
IM
714static inline void
715enqueue_task_head(struct task_struct *p, struct prio_array *array)
1da177e4
LT
716{
717 list_add(&p->run_list, array->queue + p->prio);
718 __set_bit(p->prio, array->bitmap);
719 array->nr_active++;
720 p->array = array;
721}
722
723/*
b29739f9 724 * __normal_prio - return the priority that is based on the static
1da177e4
LT
725 * priority but is modified by bonuses/penalties.
726 *
727 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
728 * into the -5 ... 0 ... +5 bonus/penalty range.
729 *
730 * We use 25% of the full 0...39 priority range so that:
731 *
732 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
733 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
734 *
735 * Both properties are important to certain workloads.
736 */
b29739f9 737
36c8b586 738static inline int __normal_prio(struct task_struct *p)
1da177e4
LT
739{
740 int bonus, prio;
741
1da177e4
LT
742 bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
743
744 prio = p->static_prio - bonus;
745 if (prio < MAX_RT_PRIO)
746 prio = MAX_RT_PRIO;
747 if (prio > MAX_PRIO-1)
748 prio = MAX_PRIO-1;
749 return prio;
750}
751
2dd73a4f
PW
752/*
753 * To aid in avoiding the subversion of "niceness" due to uneven distribution
754 * of tasks with abnormal "nice" values across CPUs the contribution that
755 * each task makes to its run queue's load is weighted according to its
756 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
757 * scaled version of the new time slice allocation that they receive on time
758 * slice expiry etc.
759 */
760
761/*
762 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
763 * If static_prio_timeslice() is ever changed to break this assumption then
764 * this code will need modification
765 */
766#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
767#define LOAD_WEIGHT(lp) \
768 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
769#define PRIO_TO_LOAD_WEIGHT(prio) \
770 LOAD_WEIGHT(static_prio_timeslice(prio))
771#define RTPRIO_TO_LOAD_WEIGHT(rp) \
772 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
773
36c8b586 774static void set_load_weight(struct task_struct *p)
2dd73a4f 775{
b29739f9 776 if (has_rt_policy(p)) {
2dd73a4f
PW
777#ifdef CONFIG_SMP
778 if (p == task_rq(p)->migration_thread)
779 /*
780 * The migration thread does the actual balancing.
781 * Giving its load any weight will skew balancing
782 * adversely.
783 */
784 p->load_weight = 0;
785 else
786#endif
787 p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
788 } else
789 p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
790}
791
36c8b586 792static inline void
70b97a7f 793inc_raw_weighted_load(struct rq *rq, const struct task_struct *p)
2dd73a4f
PW
794{
795 rq->raw_weighted_load += p->load_weight;
796}
797
36c8b586 798static inline void
70b97a7f 799dec_raw_weighted_load(struct rq *rq, const struct task_struct *p)
2dd73a4f
PW
800{
801 rq->raw_weighted_load -= p->load_weight;
802}
803
70b97a7f 804static inline void inc_nr_running(struct task_struct *p, struct rq *rq)
2dd73a4f
PW
805{
806 rq->nr_running++;
807 inc_raw_weighted_load(rq, p);
808}
809
70b97a7f 810static inline void dec_nr_running(struct task_struct *p, struct rq *rq)
2dd73a4f
PW
811{
812 rq->nr_running--;
813 dec_raw_weighted_load(rq, p);
814}
815
b29739f9
IM
816/*
817 * Calculate the expected normal priority: i.e. priority
818 * without taking RT-inheritance into account. Might be
819 * boosted by interactivity modifiers. Changes upon fork,
820 * setprio syscalls, and whenever the interactivity
821 * estimator recalculates.
822 */
36c8b586 823static inline int normal_prio(struct task_struct *p)
b29739f9
IM
824{
825 int prio;
826
827 if (has_rt_policy(p))
828 prio = MAX_RT_PRIO-1 - p->rt_priority;
829 else
830 prio = __normal_prio(p);
831 return prio;
832}
833
834/*
835 * Calculate the current priority, i.e. the priority
836 * taken into account by the scheduler. This value might
837 * be boosted by RT tasks, or might be boosted by
838 * interactivity modifiers. Will be RT if the task got
839 * RT-boosted. If not then it returns p->normal_prio.
840 */
36c8b586 841static int effective_prio(struct task_struct *p)
b29739f9
IM
842{
843 p->normal_prio = normal_prio(p);
844 /*
845 * If we are RT tasks or we were boosted to RT priority,
846 * keep the priority unchanged. Otherwise, update priority
847 * to the normal priority:
848 */
849 if (!rt_prio(p->prio))
850 return p->normal_prio;
851 return p->prio;
852}
853
1da177e4
LT
854/*
855 * __activate_task - move a task to the runqueue.
856 */
70b97a7f 857static void __activate_task(struct task_struct *p, struct rq *rq)
1da177e4 858{
70b97a7f 859 struct prio_array *target = rq->active;
d425b274 860
f1adad78 861 if (batch_task(p))
d425b274
CK
862 target = rq->expired;
863 enqueue_task(p, target);
2dd73a4f 864 inc_nr_running(p, rq);
1da177e4
LT
865}
866
867/*
868 * __activate_idle_task - move idle task to the _front_ of runqueue.
869 */
70b97a7f 870static inline void __activate_idle_task(struct task_struct *p, struct rq *rq)
1da177e4
LT
871{
872 enqueue_task_head(p, rq->active);
2dd73a4f 873 inc_nr_running(p, rq);
1da177e4
LT
874}
875
b29739f9
IM
876/*
877 * Recalculate p->normal_prio and p->prio after having slept,
878 * updating the sleep-average too:
879 */
36c8b586 880static int recalc_task_prio(struct task_struct *p, unsigned long long now)
1da177e4
LT
881{
882 /* Caller must always ensure 'now >= p->timestamp' */
72d2854d 883 unsigned long sleep_time = now - p->timestamp;
1da177e4 884
d425b274 885 if (batch_task(p))
b0a9499c 886 sleep_time = 0;
1da177e4
LT
887
888 if (likely(sleep_time > 0)) {
889 /*
72d2854d
CK
890 * This ceiling is set to the lowest priority that would allow
891 * a task to be reinserted into the active array on timeslice
892 * completion.
1da177e4 893 */
72d2854d 894 unsigned long ceiling = INTERACTIVE_SLEEP(p);
e72ff0bb 895
72d2854d
CK
896 if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) {
897 /*
898 * Prevents user tasks from achieving best priority
899 * with one single large enough sleep.
900 */
901 p->sleep_avg = ceiling;
902 /*
903 * Using INTERACTIVE_SLEEP() as a ceiling places a
904 * nice(0) task 1ms sleep away from promotion, and
905 * gives it 700ms to round-robin with no chance of
906 * being demoted. This is more than generous, so
907 * mark this sleep as non-interactive to prevent the
908 * on-runqueue bonus logic from intervening should
909 * this task not receive cpu immediately.
910 */
911 p->sleep_type = SLEEP_NONINTERACTIVE;
1da177e4 912 } else {
1da177e4
LT
913 /*
914 * Tasks waking from uninterruptible sleep are
915 * limited in their sleep_avg rise as they
916 * are likely to be waiting on I/O
917 */
3dee386e 918 if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) {
72d2854d 919 if (p->sleep_avg >= ceiling)
1da177e4
LT
920 sleep_time = 0;
921 else if (p->sleep_avg + sleep_time >=
72d2854d
CK
922 ceiling) {
923 p->sleep_avg = ceiling;
924 sleep_time = 0;
1da177e4
LT
925 }
926 }
927
928 /*
929 * This code gives a bonus to interactive tasks.
930 *
931 * The boost works by updating the 'average sleep time'
932 * value here, based on ->timestamp. The more time a
933 * task spends sleeping, the higher the average gets -
934 * and the higher the priority boost gets as well.
935 */
936 p->sleep_avg += sleep_time;
937
1da177e4 938 }
72d2854d
CK
939 if (p->sleep_avg > NS_MAX_SLEEP_AVG)
940 p->sleep_avg = NS_MAX_SLEEP_AVG;
1da177e4
LT
941 }
942
a3464a10 943 return effective_prio(p);
1da177e4
LT
944}
945
946/*
947 * activate_task - move a task to the runqueue and do priority recalculation
948 *
949 * Update all the scheduling statistics stuff. (sleep average
950 * calculation, priority modifiers, etc.)
951 */
70b97a7f 952static void activate_task(struct task_struct *p, struct rq *rq, int local)
1da177e4
LT
953{
954 unsigned long long now;
955
62ab616d
CK
956 if (rt_task(p))
957 goto out;
958
1da177e4
LT
959 now = sched_clock();
960#ifdef CONFIG_SMP
961 if (!local) {
962 /* Compensate for drifting sched_clock */
70b97a7f 963 struct rq *this_rq = this_rq();
b18ec803
MG
964 now = (now - this_rq->most_recent_timestamp)
965 + rq->most_recent_timestamp;
1da177e4
LT
966 }
967#endif
968
ece8a684
IM
969 /*
970 * Sleep time is in units of nanosecs, so shift by 20 to get a
971 * milliseconds-range estimation of the amount of time that the task
972 * spent sleeping:
973 */
974 if (unlikely(prof_on == SLEEP_PROFILING)) {
975 if (p->state == TASK_UNINTERRUPTIBLE)
976 profile_hits(SLEEP_PROFILING, (void *)get_wchan(p),
977 (now - p->timestamp) >> 20);
978 }
979
62ab616d 980 p->prio = recalc_task_prio(p, now);
1da177e4
LT
981
982 /*
983 * This checks to make sure it's not an uninterruptible task
984 * that is now waking up.
985 */
3dee386e 986 if (p->sleep_type == SLEEP_NORMAL) {
1da177e4
LT
987 /*
988 * Tasks which were woken up by interrupts (ie. hw events)
989 * are most likely of interactive nature. So we give them
990 * the credit of extending their sleep time to the period
991 * of time they spend on the runqueue, waiting for execution
992 * on a CPU, first time around:
993 */
994 if (in_interrupt())
3dee386e 995 p->sleep_type = SLEEP_INTERRUPTED;
1da177e4
LT
996 else {
997 /*
998 * Normal first-time wakeups get a credit too for
999 * on-runqueue time, but it will be weighted down:
1000 */
3dee386e 1001 p->sleep_type = SLEEP_INTERACTIVE;
1da177e4
LT
1002 }
1003 }
1004 p->timestamp = now;
62ab616d 1005out:
1da177e4
LT
1006 __activate_task(p, rq);
1007}
1008
1009/*
1010 * deactivate_task - remove a task from the runqueue.
1011 */
70b97a7f 1012static void deactivate_task(struct task_struct *p, struct rq *rq)
1da177e4 1013{
2dd73a4f 1014 dec_nr_running(p, rq);
1da177e4
LT
1015 dequeue_task(p, p->array);
1016 p->array = NULL;
1017}
1018
1019/*
1020 * resched_task - mark a task 'to be rescheduled now'.
1021 *
1022 * On UP this means the setting of the need_resched flag, on SMP it
1023 * might also involve a cross-CPU call to trigger the scheduler on
1024 * the target CPU.
1025 */
1026#ifdef CONFIG_SMP
495ab9c0
AK
1027
1028#ifndef tsk_is_polling
1029#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1030#endif
1031
36c8b586 1032static void resched_task(struct task_struct *p)
1da177e4 1033{
64c7c8f8 1034 int cpu;
1da177e4
LT
1035
1036 assert_spin_locked(&task_rq(p)->lock);
1037
64c7c8f8
NP
1038 if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED)))
1039 return;
1040
1041 set_tsk_thread_flag(p, TIF_NEED_RESCHED);
1da177e4 1042
64c7c8f8
NP
1043 cpu = task_cpu(p);
1044 if (cpu == smp_processor_id())
1045 return;
1046
495ab9c0 1047 /* NEED_RESCHED must be visible before we test polling */
64c7c8f8 1048 smp_mb();
495ab9c0 1049 if (!tsk_is_polling(p))
64c7c8f8 1050 smp_send_reschedule(cpu);
1da177e4
LT
1051}
1052#else
36c8b586 1053static inline void resched_task(struct task_struct *p)
1da177e4 1054{
64c7c8f8 1055 assert_spin_locked(&task_rq(p)->lock);
1da177e4
LT
1056 set_tsk_need_resched(p);
1057}
1058#endif
1059
1060/**
1061 * task_curr - is this task currently executing on a CPU?
1062 * @p: the task in question.
1063 */
36c8b586 1064inline int task_curr(const struct task_struct *p)
1da177e4
LT
1065{
1066 return cpu_curr(task_cpu(p)) == p;
1067}
1068
2dd73a4f
PW
1069/* Used instead of source_load when we know the type == 0 */
1070unsigned long weighted_cpuload(const int cpu)
1071{
1072 return cpu_rq(cpu)->raw_weighted_load;
1073}
1074
1da177e4 1075#ifdef CONFIG_SMP
70b97a7f 1076struct migration_req {
1da177e4 1077 struct list_head list;
1da177e4 1078
36c8b586 1079 struct task_struct *task;
1da177e4
LT
1080 int dest_cpu;
1081
1da177e4 1082 struct completion done;
70b97a7f 1083};
1da177e4
LT
1084
1085/*
1086 * The task's runqueue lock must be held.
1087 * Returns true if you have to wait for migration thread.
1088 */
36c8b586 1089static int
70b97a7f 1090migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
1da177e4 1091{
70b97a7f 1092 struct rq *rq = task_rq(p);
1da177e4
LT
1093
1094 /*
1095 * If the task is not on a runqueue (and not running), then
1096 * it is sufficient to simply update the task's cpu field.
1097 */
1098 if (!p->array && !task_running(rq, p)) {
1099 set_task_cpu(p, dest_cpu);
1100 return 0;
1101 }
1102
1103 init_completion(&req->done);
1da177e4
LT
1104 req->task = p;
1105 req->dest_cpu = dest_cpu;
1106 list_add(&req->list, &rq->migration_queue);
48f24c4d 1107
1da177e4
LT
1108 return 1;
1109}
1110
1111/*
1112 * wait_task_inactive - wait for a thread to unschedule.
1113 *
1114 * The caller must ensure that the task *will* unschedule sometime soon,
1115 * else this function might spin for a *long* time. This function can't
1116 * be called with interrupts off, or it may introduce deadlock with
1117 * smp_call_function() if an IPI is sent by the same process we are
1118 * waiting to become inactive.
1119 */
36c8b586 1120void wait_task_inactive(struct task_struct *p)
1da177e4
LT
1121{
1122 unsigned long flags;
70b97a7f 1123 struct rq *rq;
1da177e4
LT
1124 int preempted;
1125
1126repeat:
1127 rq = task_rq_lock(p, &flags);
1128 /* Must be off runqueue entirely, not preempted. */
1129 if (unlikely(p->array || task_running(rq, p))) {
1130 /* If it's preempted, we yield. It could be a while. */
1131 preempted = !task_running(rq, p);
1132 task_rq_unlock(rq, &flags);
1133 cpu_relax();
1134 if (preempted)
1135 yield();
1136 goto repeat;
1137 }
1138 task_rq_unlock(rq, &flags);
1139}
1140
1141/***
1142 * kick_process - kick a running thread to enter/exit the kernel
1143 * @p: the to-be-kicked thread
1144 *
1145 * Cause a process which is running on another CPU to enter
1146 * kernel-mode, without any delay. (to get signals handled.)
1147 *
1148 * NOTE: this function doesnt have to take the runqueue lock,
1149 * because all it wants to ensure is that the remote task enters
1150 * the kernel. If the IPI races and the task has been migrated
1151 * to another CPU then no harm is done and the purpose has been
1152 * achieved as well.
1153 */
36c8b586 1154void kick_process(struct task_struct *p)
1da177e4
LT
1155{
1156 int cpu;
1157
1158 preempt_disable();
1159 cpu = task_cpu(p);
1160 if ((cpu != smp_processor_id()) && task_curr(p))
1161 smp_send_reschedule(cpu);
1162 preempt_enable();
1163}
1164
1165/*
2dd73a4f
PW
1166 * Return a low guess at the load of a migration-source cpu weighted
1167 * according to the scheduling class and "nice" value.
1da177e4
LT
1168 *
1169 * We want to under-estimate the load of migration sources, to
1170 * balance conservatively.
1171 */
a2000572 1172static inline unsigned long source_load(int cpu, int type)
1da177e4 1173{
70b97a7f 1174 struct rq *rq = cpu_rq(cpu);
2dd73a4f 1175
3b0bd9bc 1176 if (type == 0)
2dd73a4f 1177 return rq->raw_weighted_load;
b910472d 1178
2dd73a4f 1179 return min(rq->cpu_load[type-1], rq->raw_weighted_load);
1da177e4
LT
1180}
1181
1182/*
2dd73a4f
PW
1183 * Return a high guess at the load of a migration-target cpu weighted
1184 * according to the scheduling class and "nice" value.
1da177e4 1185 */
a2000572 1186static inline unsigned long target_load(int cpu, int type)
1da177e4 1187{
70b97a7f 1188 struct rq *rq = cpu_rq(cpu);
2dd73a4f 1189
7897986b 1190 if (type == 0)
2dd73a4f 1191 return rq->raw_weighted_load;
3b0bd9bc 1192
2dd73a4f
PW
1193 return max(rq->cpu_load[type-1], rq->raw_weighted_load);
1194}
1195
1196/*
1197 * Return the average load per task on the cpu's run queue
1198 */
1199static inline unsigned long cpu_avg_load_per_task(int cpu)
1200{
70b97a7f 1201 struct rq *rq = cpu_rq(cpu);
2dd73a4f
PW
1202 unsigned long n = rq->nr_running;
1203
48f24c4d 1204 return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE;
1da177e4
LT
1205}
1206
147cbb4b
NP
1207/*
1208 * find_idlest_group finds and returns the least busy CPU group within the
1209 * domain.
1210 */
1211static struct sched_group *
1212find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
1213{
1214 struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
1215 unsigned long min_load = ULONG_MAX, this_load = 0;
1216 int load_idx = sd->forkexec_idx;
1217 int imbalance = 100 + (sd->imbalance_pct-100)/2;
1218
1219 do {
1220 unsigned long load, avg_load;
1221 int local_group;
1222 int i;
1223
da5a5522
BD
1224 /* Skip over this group if it has no CPUs allowed */
1225 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
1226 goto nextgroup;
1227
147cbb4b 1228 local_group = cpu_isset(this_cpu, group->cpumask);
147cbb4b
NP
1229
1230 /* Tally up the load of all CPUs in the group */
1231 avg_load = 0;
1232
1233 for_each_cpu_mask(i, group->cpumask) {
1234 /* Bias balancing toward cpus of our domain */
1235 if (local_group)
1236 load = source_load(i, load_idx);
1237 else
1238 load = target_load(i, load_idx);
1239
1240 avg_load += load;
1241 }
1242
1243 /* Adjust by relative CPU power of the group */
1244 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
1245
1246 if (local_group) {
1247 this_load = avg_load;
1248 this = group;
1249 } else if (avg_load < min_load) {
1250 min_load = avg_load;
1251 idlest = group;
1252 }
da5a5522 1253nextgroup:
147cbb4b
NP
1254 group = group->next;
1255 } while (group != sd->groups);
1256
1257 if (!idlest || 100*this_load < imbalance*min_load)
1258 return NULL;
1259 return idlest;
1260}
1261
1262/*
0feaece9 1263 * find_idlest_cpu - find the idlest cpu among the cpus in group.
147cbb4b 1264 */
95cdf3b7
IM
1265static int
1266find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
147cbb4b 1267{
da5a5522 1268 cpumask_t tmp;
147cbb4b
NP
1269 unsigned long load, min_load = ULONG_MAX;
1270 int idlest = -1;
1271 int i;
1272
da5a5522
BD
1273 /* Traverse only the allowed CPUs */
1274 cpus_and(tmp, group->cpumask, p->cpus_allowed);
1275
1276 for_each_cpu_mask(i, tmp) {
2dd73a4f 1277 load = weighted_cpuload(i);
147cbb4b
NP
1278
1279 if (load < min_load || (load == min_load && i == this_cpu)) {
1280 min_load = load;
1281 idlest = i;
1282 }
1283 }
1284
1285 return idlest;
1286}
1287
476d139c
NP
1288/*
1289 * sched_balance_self: balance the current task (running on cpu) in domains
1290 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1291 * SD_BALANCE_EXEC.
1292 *
1293 * Balance, ie. select the least loaded group.
1294 *
1295 * Returns the target CPU number, or the same CPU if no balancing is needed.
1296 *
1297 * preempt must be disabled.
1298 */
1299static int sched_balance_self(int cpu, int flag)
1300{
1301 struct task_struct *t = current;
1302 struct sched_domain *tmp, *sd = NULL;
147cbb4b 1303
c96d145e 1304 for_each_domain(cpu, tmp) {
5c45bf27
SS
1305 /*
1306 * If power savings logic is enabled for a domain, stop there.
1307 */
1308 if (tmp->flags & SD_POWERSAVINGS_BALANCE)
1309 break;
476d139c
NP
1310 if (tmp->flags & flag)
1311 sd = tmp;
c96d145e 1312 }
476d139c
NP
1313
1314 while (sd) {
1315 cpumask_t span;
1316 struct sched_group *group;
1a848870
SS
1317 int new_cpu, weight;
1318
1319 if (!(sd->flags & flag)) {
1320 sd = sd->child;
1321 continue;
1322 }
476d139c
NP
1323
1324 span = sd->span;
1325 group = find_idlest_group(sd, t, cpu);
1a848870
SS
1326 if (!group) {
1327 sd = sd->child;
1328 continue;
1329 }
476d139c 1330
da5a5522 1331 new_cpu = find_idlest_cpu(group, t, cpu);
1a848870
SS
1332 if (new_cpu == -1 || new_cpu == cpu) {
1333 /* Now try balancing at a lower domain level of cpu */
1334 sd = sd->child;
1335 continue;
1336 }
476d139c 1337
1a848870 1338 /* Now try balancing at a lower domain level of new_cpu */
476d139c 1339 cpu = new_cpu;
476d139c
NP
1340 sd = NULL;
1341 weight = cpus_weight(span);
1342 for_each_domain(cpu, tmp) {
1343 if (weight <= cpus_weight(tmp->span))
1344 break;
1345 if (tmp->flags & flag)
1346 sd = tmp;
1347 }
1348 /* while loop will break here if sd == NULL */
1349 }
1350
1351 return cpu;
1352}
1353
1354#endif /* CONFIG_SMP */
1da177e4
LT
1355
1356/*
1357 * wake_idle() will wake a task on an idle cpu if task->cpu is
1358 * not idle and an idle cpu is available. The span of cpus to
1359 * search starts with cpus closest then further out as needed,
1360 * so we always favor a closer, idle cpu.
1361 *
1362 * Returns the CPU we should wake onto.
1363 */
1364#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
36c8b586 1365static int wake_idle(int cpu, struct task_struct *p)
1da177e4
LT
1366{
1367 cpumask_t tmp;
1368 struct sched_domain *sd;
1369 int i;
1370
1371 if (idle_cpu(cpu))
1372 return cpu;
1373
1374 for_each_domain(cpu, sd) {
1375 if (sd->flags & SD_WAKE_IDLE) {
e0f364f4 1376 cpus_and(tmp, sd->span, p->cpus_allowed);
1da177e4
LT
1377 for_each_cpu_mask(i, tmp) {
1378 if (idle_cpu(i))
1379 return i;
1380 }
1381 }
e0f364f4
NP
1382 else
1383 break;
1da177e4
LT
1384 }
1385 return cpu;
1386}
1387#else
36c8b586 1388static inline int wake_idle(int cpu, struct task_struct *p)
1da177e4
LT
1389{
1390 return cpu;
1391}
1392#endif
1393
1394/***
1395 * try_to_wake_up - wake up a thread
1396 * @p: the to-be-woken-up thread
1397 * @state: the mask of task states that can be woken
1398 * @sync: do a synchronous wakeup?
1399 *
1400 * Put it on the run-queue if it's not already there. The "current"
1401 * thread is always on the run-queue (except when the actual
1402 * re-schedule is in progress), and as such you're allowed to do
1403 * the simpler "current->state = TASK_RUNNING" to mark yourself
1404 * runnable without the overhead of this.
1405 *
1406 * returns failure only if the task is already active.
1407 */
36c8b586 1408static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
1da177e4
LT
1409{
1410 int cpu, this_cpu, success = 0;
1411 unsigned long flags;
1412 long old_state;
70b97a7f 1413 struct rq *rq;
1da177e4 1414#ifdef CONFIG_SMP
7897986b 1415 struct sched_domain *sd, *this_sd = NULL;
70b97a7f 1416 unsigned long load, this_load;
1da177e4
LT
1417 int new_cpu;
1418#endif
1419
1420 rq = task_rq_lock(p, &flags);
1421 old_state = p->state;
1422 if (!(old_state & state))
1423 goto out;
1424
1425 if (p->array)
1426 goto out_running;
1427
1428 cpu = task_cpu(p);
1429 this_cpu = smp_processor_id();
1430
1431#ifdef CONFIG_SMP
1432 if (unlikely(task_running(rq, p)))
1433 goto out_activate;
1434
7897986b
NP
1435 new_cpu = cpu;
1436
1da177e4
LT
1437 schedstat_inc(rq, ttwu_cnt);
1438 if (cpu == this_cpu) {
1439 schedstat_inc(rq, ttwu_local);
7897986b
NP
1440 goto out_set_cpu;
1441 }
1442
1443 for_each_domain(this_cpu, sd) {
1444 if (cpu_isset(cpu, sd->span)) {
1445 schedstat_inc(sd, ttwu_wake_remote);
1446 this_sd = sd;
1447 break;
1da177e4
LT
1448 }
1449 }
1da177e4 1450
7897986b 1451 if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1da177e4
LT
1452 goto out_set_cpu;
1453
1da177e4 1454 /*
7897986b 1455 * Check for affine wakeup and passive balancing possibilities.
1da177e4 1456 */
7897986b
NP
1457 if (this_sd) {
1458 int idx = this_sd->wake_idx;
1459 unsigned int imbalance;
1da177e4 1460
a3f21bce
NP
1461 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1462
7897986b
NP
1463 load = source_load(cpu, idx);
1464 this_load = target_load(this_cpu, idx);
1da177e4 1465
7897986b
NP
1466 new_cpu = this_cpu; /* Wake to this CPU if we can */
1467
a3f21bce
NP
1468 if (this_sd->flags & SD_WAKE_AFFINE) {
1469 unsigned long tl = this_load;
33859f7f
MOS
1470 unsigned long tl_per_task;
1471
1472 tl_per_task = cpu_avg_load_per_task(this_cpu);
2dd73a4f 1473
1da177e4 1474 /*
a3f21bce
NP
1475 * If sync wakeup then subtract the (maximum possible)
1476 * effect of the currently running task from the load
1477 * of the current CPU:
1da177e4 1478 */
a3f21bce 1479 if (sync)
2dd73a4f 1480 tl -= current->load_weight;
a3f21bce
NP
1481
1482 if ((tl <= load &&
2dd73a4f
PW
1483 tl + target_load(cpu, idx) <= tl_per_task) ||
1484 100*(tl + p->load_weight) <= imbalance*load) {
a3f21bce
NP
1485 /*
1486 * This domain has SD_WAKE_AFFINE and
1487 * p is cache cold in this domain, and
1488 * there is no bad imbalance.
1489 */
1490 schedstat_inc(this_sd, ttwu_move_affine);
1491 goto out_set_cpu;
1492 }
1493 }
1494
1495 /*
1496 * Start passive balancing when half the imbalance_pct
1497 * limit is reached.
1498 */
1499 if (this_sd->flags & SD_WAKE_BALANCE) {
1500 if (imbalance*this_load <= 100*load) {
1501 schedstat_inc(this_sd, ttwu_move_balance);
1502 goto out_set_cpu;
1503 }
1da177e4
LT
1504 }
1505 }
1506
1507 new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
1508out_set_cpu:
1509 new_cpu = wake_idle(new_cpu, p);
1510 if (new_cpu != cpu) {
1511 set_task_cpu(p, new_cpu);
1512 task_rq_unlock(rq, &flags);
1513 /* might preempt at this point */
1514 rq = task_rq_lock(p, &flags);
1515 old_state = p->state;
1516 if (!(old_state & state))
1517 goto out;
1518 if (p->array)
1519 goto out_running;
1520
1521 this_cpu = smp_processor_id();
1522 cpu = task_cpu(p);
1523 }
1524
1525out_activate:
1526#endif /* CONFIG_SMP */
1527 if (old_state == TASK_UNINTERRUPTIBLE) {
1528 rq->nr_uninterruptible--;
1529 /*
1530 * Tasks on involuntary sleep don't earn
1531 * sleep_avg beyond just interactive state.
1532 */
3dee386e 1533 p->sleep_type = SLEEP_NONINTERACTIVE;
e7c38cb4 1534 } else
1da177e4 1535
d79fc0fc
IM
1536 /*
1537 * Tasks that have marked their sleep as noninteractive get
e7c38cb4
CK
1538 * woken up with their sleep average not weighted in an
1539 * interactive way.
d79fc0fc 1540 */
e7c38cb4
CK
1541 if (old_state & TASK_NONINTERACTIVE)
1542 p->sleep_type = SLEEP_NONINTERACTIVE;
1543
1544
1545 activate_task(p, rq, cpu == this_cpu);
1da177e4
LT
1546 /*
1547 * Sync wakeups (i.e. those types of wakeups where the waker
1548 * has indicated that it will leave the CPU in short order)
1549 * don't trigger a preemption, if the woken up task will run on
1550 * this cpu. (in this case the 'I will reschedule' promise of
1551 * the waker guarantees that the freshly woken up task is going
1552 * to be considered on this CPU.)
1553 */
1da177e4
LT
1554 if (!sync || cpu != this_cpu) {
1555 if (TASK_PREEMPTS_CURR(p, rq))
1556 resched_task(rq->curr);
1557 }
1558 success = 1;
1559
1560out_running:
1561 p->state = TASK_RUNNING;
1562out:
1563 task_rq_unlock(rq, &flags);
1564
1565 return success;
1566}
1567
36c8b586 1568int fastcall wake_up_process(struct task_struct *p)
1da177e4
LT
1569{
1570 return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1571 TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1572}
1da177e4
LT
1573EXPORT_SYMBOL(wake_up_process);
1574
36c8b586 1575int fastcall wake_up_state(struct task_struct *p, unsigned int state)
1da177e4
LT
1576{
1577 return try_to_wake_up(p, state, 0);
1578}
1579
bc947631 1580static void task_running_tick(struct rq *rq, struct task_struct *p);
1da177e4
LT
1581/*
1582 * Perform scheduler related setup for a newly forked process p.
1583 * p is forked by current.
1584 */
36c8b586 1585void fastcall sched_fork(struct task_struct *p, int clone_flags)
1da177e4 1586{
476d139c
NP
1587 int cpu = get_cpu();
1588
1589#ifdef CONFIG_SMP
1590 cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1591#endif
1592 set_task_cpu(p, cpu);
1593
1da177e4
LT
1594 /*
1595 * We mark the process as running here, but have not actually
1596 * inserted it onto the runqueue yet. This guarantees that
1597 * nobody will actually run it, and a signal or other external
1598 * event cannot wake it up and insert it on the runqueue either.
1599 */
1600 p->state = TASK_RUNNING;
b29739f9
IM
1601
1602 /*
1603 * Make sure we do not leak PI boosting priority to the child:
1604 */
1605 p->prio = current->normal_prio;
1606
1da177e4
LT
1607 INIT_LIST_HEAD(&p->run_list);
1608 p->array = NULL;
52f17b6c
CS
1609#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1610 if (unlikely(sched_info_on()))
1611 memset(&p->sched_info, 0, sizeof(p->sched_info));
1da177e4 1612#endif
d6077cb8 1613#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4866cde0
NP
1614 p->oncpu = 0;
1615#endif
1da177e4 1616#ifdef CONFIG_PREEMPT
4866cde0 1617 /* Want to start with kernel preemption disabled. */
a1261f54 1618 task_thread_info(p)->preempt_count = 1;
1da177e4
LT
1619#endif
1620 /*
1621 * Share the timeslice between parent and child, thus the
1622 * total amount of pending timeslices in the system doesn't change,
1623 * resulting in more scheduling fairness.
1624 */
1625 local_irq_disable();
1626 p->time_slice = (current->time_slice + 1) >> 1;
1627 /*
1628 * The remainder of the first timeslice might be recovered by
1629 * the parent if the child exits early enough.
1630 */
1631 p->first_time_slice = 1;
1632 current->time_slice >>= 1;
1633 p->timestamp = sched_clock();
1634 if (unlikely(!current->time_slice)) {
1635 /*
1636 * This case is rare, it happens when the parent has only
1637 * a single jiffy left from its timeslice. Taking the
1638 * runqueue lock is not a problem.
1639 */
1640 current->time_slice = 1;
bc947631 1641 task_running_tick(cpu_rq(cpu), current);
476d139c
NP
1642 }
1643 local_irq_enable();
1644 put_cpu();
1da177e4
LT
1645}
1646
1647/*
1648 * wake_up_new_task - wake up a newly created task for the first time.
1649 *
1650 * This function will do some initial scheduler statistics housekeeping
1651 * that must be done for every newly created context, then puts the task
1652 * on the runqueue and wakes it.
1653 */
36c8b586 1654void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
1da177e4 1655{
70b97a7f 1656 struct rq *rq, *this_rq;
1da177e4
LT
1657 unsigned long flags;
1658 int this_cpu, cpu;
1da177e4
LT
1659
1660 rq = task_rq_lock(p, &flags);
147cbb4b 1661 BUG_ON(p->state != TASK_RUNNING);
1da177e4 1662 this_cpu = smp_processor_id();
147cbb4b 1663 cpu = task_cpu(p);
1da177e4 1664
1da177e4
LT
1665 /*
1666 * We decrease the sleep average of forking parents
1667 * and children as well, to keep max-interactive tasks
1668 * from forking tasks that are max-interactive. The parent
1669 * (current) is done further down, under its lock.
1670 */
1671 p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
1672 CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1673
1674 p->prio = effective_prio(p);
1675
1676 if (likely(cpu == this_cpu)) {
1677 if (!(clone_flags & CLONE_VM)) {
1678 /*
1679 * The VM isn't cloned, so we're in a good position to
1680 * do child-runs-first in anticipation of an exec. This
1681 * usually avoids a lot of COW overhead.
1682 */
1683 if (unlikely(!current->array))
1684 __activate_task(p, rq);
1685 else {
1686 p->prio = current->prio;
b29739f9 1687 p->normal_prio = current->normal_prio;
1da177e4
LT
1688 list_add_tail(&p->run_list, &current->run_list);
1689 p->array = current->array;
1690 p->array->nr_active++;
2dd73a4f 1691 inc_nr_running(p, rq);
1da177e4
LT
1692 }
1693 set_need_resched();
1694 } else
1695 /* Run child last */
1696 __activate_task(p, rq);
1697 /*
1698 * We skip the following code due to cpu == this_cpu
1699 *
1700 * task_rq_unlock(rq, &flags);
1701 * this_rq = task_rq_lock(current, &flags);
1702 */
1703 this_rq = rq;
1704 } else {
1705 this_rq = cpu_rq(this_cpu);
1706
1707 /*
1708 * Not the local CPU - must adjust timestamp. This should
1709 * get optimised away in the !CONFIG_SMP case.
1710 */
b18ec803
MG
1711 p->timestamp = (p->timestamp - this_rq->most_recent_timestamp)
1712 + rq->most_recent_timestamp;
1da177e4
LT
1713 __activate_task(p, rq);
1714 if (TASK_PREEMPTS_CURR(p, rq))
1715 resched_task(rq->curr);
1716
1717 /*
1718 * Parent and child are on different CPUs, now get the
1719 * parent runqueue to update the parent's ->sleep_avg:
1720 */
1721 task_rq_unlock(rq, &flags);
1722 this_rq = task_rq_lock(current, &flags);
1723 }
1724 current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
1725 PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1726 task_rq_unlock(this_rq, &flags);
1727}
1728
1729/*
1730 * Potentially available exiting-child timeslices are
1731 * retrieved here - this way the parent does not get
1732 * penalized for creating too many threads.
1733 *
1734 * (this cannot be used to 'generate' timeslices
1735 * artificially, because any timeslice recovered here
1736 * was given away by the parent in the first place.)
1737 */
36c8b586 1738void fastcall sched_exit(struct task_struct *p)
1da177e4
LT
1739{
1740 unsigned long flags;
70b97a7f 1741 struct rq *rq;
1da177e4
LT
1742
1743 /*
1744 * If the child was a (relative-) CPU hog then decrease
1745 * the sleep_avg of the parent as well.
1746 */
1747 rq = task_rq_lock(p->parent, &flags);
889dfafe 1748 if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) {
1da177e4
LT
1749 p->parent->time_slice += p->time_slice;
1750 if (unlikely(p->parent->time_slice > task_timeslice(p)))
1751 p->parent->time_slice = task_timeslice(p);
1752 }
1753 if (p->sleep_avg < p->parent->sleep_avg)
1754 p->parent->sleep_avg = p->parent->sleep_avg /
1755 (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
1756 (EXIT_WEIGHT + 1);
1757 task_rq_unlock(rq, &flags);
1758}
1759
4866cde0
NP
1760/**
1761 * prepare_task_switch - prepare to switch tasks
1762 * @rq: the runqueue preparing to switch
1763 * @next: the task we are going to switch to.
1764 *
1765 * This is called with the rq lock held and interrupts off. It must
1766 * be paired with a subsequent finish_task_switch after the context
1767 * switch.
1768 *
1769 * prepare_task_switch sets up locking and calls architecture specific
1770 * hooks.
1771 */
70b97a7f 1772static inline void prepare_task_switch(struct rq *rq, struct task_struct *next)
4866cde0
NP
1773{
1774 prepare_lock_switch(rq, next);
1775 prepare_arch_switch(next);
1776}
1777
1da177e4
LT
1778/**
1779 * finish_task_switch - clean up after a task-switch
344babaa 1780 * @rq: runqueue associated with task-switch
1da177e4
LT
1781 * @prev: the thread we just switched away from.
1782 *
4866cde0
NP
1783 * finish_task_switch must be called after the context switch, paired
1784 * with a prepare_task_switch call before the context switch.
1785 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1786 * and do any other architecture-specific cleanup actions.
1da177e4
LT
1787 *
1788 * Note that we may have delayed dropping an mm in context_switch(). If
1789 * so, we finish that here outside of the runqueue lock. (Doing it
1790 * with the lock held can cause deadlocks; see schedule() for
1791 * details.)
1792 */
70b97a7f 1793static inline void finish_task_switch(struct rq *rq, struct task_struct *prev)
1da177e4
LT
1794 __releases(rq->lock)
1795{
1da177e4 1796 struct mm_struct *mm = rq->prev_mm;
55a101f8 1797 long prev_state;
1da177e4
LT
1798
1799 rq->prev_mm = NULL;
1800
1801 /*
1802 * A task struct has one reference for the use as "current".
c394cc9f 1803 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
55a101f8
ON
1804 * schedule one last time. The schedule call will never return, and
1805 * the scheduled task must drop that reference.
c394cc9f 1806 * The test for TASK_DEAD must occur while the runqueue locks are
1da177e4
LT
1807 * still held, otherwise prev could be scheduled on another cpu, die
1808 * there before we look at prev->state, and then the reference would
1809 * be dropped twice.
1810 * Manfred Spraul <manfred@colorfullife.com>
1811 */
55a101f8 1812 prev_state = prev->state;
4866cde0
NP
1813 finish_arch_switch(prev);
1814 finish_lock_switch(rq, prev);
1da177e4
LT
1815 if (mm)
1816 mmdrop(mm);
c394cc9f 1817 if (unlikely(prev_state == TASK_DEAD)) {
c6fd91f0 1818 /*
1819 * Remove function-return probe instances associated with this
1820 * task and put them back on the free list.
1821 */
1822 kprobe_flush_task(prev);
1da177e4 1823 put_task_struct(prev);
c6fd91f0 1824 }
1da177e4
LT
1825}
1826
1827/**
1828 * schedule_tail - first thing a freshly forked thread must call.
1829 * @prev: the thread we just switched away from.
1830 */
36c8b586 1831asmlinkage void schedule_tail(struct task_struct *prev)
1da177e4
LT
1832 __releases(rq->lock)
1833{
70b97a7f
IM
1834 struct rq *rq = this_rq();
1835
4866cde0
NP
1836 finish_task_switch(rq, prev);
1837#ifdef __ARCH_WANT_UNLOCKED_CTXSW
1838 /* In this case, finish_task_switch does not reenable preemption */
1839 preempt_enable();
1840#endif
1da177e4
LT
1841 if (current->set_child_tid)
1842 put_user(current->pid, current->set_child_tid);
1843}
1844
1845/*
1846 * context_switch - switch to the new MM and the new
1847 * thread's register state.
1848 */
36c8b586 1849static inline struct task_struct *
70b97a7f 1850context_switch(struct rq *rq, struct task_struct *prev,
36c8b586 1851 struct task_struct *next)
1da177e4
LT
1852{
1853 struct mm_struct *mm = next->mm;
1854 struct mm_struct *oldmm = prev->active_mm;
1855
9226d125
ZA
1856 /*
1857 * For paravirt, this is coupled with an exit in switch_to to
1858 * combine the page table reload and the switch backend into
1859 * one hypercall.
1860 */
1861 arch_enter_lazy_cpu_mode();
1862
beed33a8 1863 if (!mm) {
1da177e4
LT
1864 next->active_mm = oldmm;
1865 atomic_inc(&oldmm->mm_count);
1866 enter_lazy_tlb(oldmm, next);
1867 } else
1868 switch_mm(oldmm, mm, next);
1869
beed33a8 1870 if (!prev->mm) {
1da177e4
LT
1871 prev->active_mm = NULL;
1872 WARN_ON(rq->prev_mm);
1873 rq->prev_mm = oldmm;
1874 }
3a5f5e48
IM
1875 /*
1876 * Since the runqueue lock will be released by the next
1877 * task (which is an invalid locking op but in the case
1878 * of the scheduler it's an obvious special-case), so we
1879 * do an early lockdep release here:
1880 */
1881#ifndef __ARCH_WANT_UNLOCKED_CTXSW
8a25d5de 1882 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
3a5f5e48 1883#endif
1da177e4
LT
1884
1885 /* Here we just switch the register state and the stack. */
1886 switch_to(prev, next, prev);
1887
1888 return prev;
1889}
1890
1891/*
1892 * nr_running, nr_uninterruptible and nr_context_switches:
1893 *
1894 * externally visible scheduler statistics: current number of runnable
1895 * threads, current number of uninterruptible-sleeping threads, total
1896 * number of context switches performed since bootup.
1897 */
1898unsigned long nr_running(void)
1899{
1900 unsigned long i, sum = 0;
1901
1902 for_each_online_cpu(i)
1903 sum += cpu_rq(i)->nr_running;
1904
1905 return sum;
1906}
1907
1908unsigned long nr_uninterruptible(void)
1909{
1910 unsigned long i, sum = 0;
1911
0a945022 1912 for_each_possible_cpu(i)
1da177e4
LT
1913 sum += cpu_rq(i)->nr_uninterruptible;
1914
1915 /*
1916 * Since we read the counters lockless, it might be slightly
1917 * inaccurate. Do not allow it to go below zero though:
1918 */
1919 if (unlikely((long)sum < 0))
1920 sum = 0;
1921
1922 return sum;
1923}
1924
1925unsigned long long nr_context_switches(void)
1926{
cc94abfc
SR
1927 int i;
1928 unsigned long long sum = 0;
1da177e4 1929
0a945022 1930 for_each_possible_cpu(i)
1da177e4
LT
1931 sum += cpu_rq(i)->nr_switches;
1932
1933 return sum;
1934}
1935
1936unsigned long nr_iowait(void)
1937{
1938 unsigned long i, sum = 0;
1939
0a945022 1940 for_each_possible_cpu(i)
1da177e4
LT
1941 sum += atomic_read(&cpu_rq(i)->nr_iowait);
1942
1943 return sum;
1944}
1945
db1b1fef
JS
1946unsigned long nr_active(void)
1947{
1948 unsigned long i, running = 0, uninterruptible = 0;
1949
1950 for_each_online_cpu(i) {
1951 running += cpu_rq(i)->nr_running;
1952 uninterruptible += cpu_rq(i)->nr_uninterruptible;
1953 }
1954
1955 if (unlikely((long)uninterruptible < 0))
1956 uninterruptible = 0;
1957
1958 return running + uninterruptible;
1959}
1960
1da177e4
LT
1961#ifdef CONFIG_SMP
1962
48f24c4d
IM
1963/*
1964 * Is this task likely cache-hot:
1965 */
1966static inline int
1967task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd)
1968{
1969 return (long long)(now - p->last_ran) < (long long)sd->cache_hot_time;
1970}
1971
1da177e4
LT
1972/*
1973 * double_rq_lock - safely lock two runqueues
1974 *
1975 * Note this does not disable interrupts like task_rq_lock,
1976 * you need to do so manually before calling.
1977 */
70b97a7f 1978static void double_rq_lock(struct rq *rq1, struct rq *rq2)
1da177e4
LT
1979 __acquires(rq1->lock)
1980 __acquires(rq2->lock)
1981{
054b9108 1982 BUG_ON(!irqs_disabled());
1da177e4
LT
1983 if (rq1 == rq2) {
1984 spin_lock(&rq1->lock);
1985 __acquire(rq2->lock); /* Fake it out ;) */
1986 } else {
c96d145e 1987 if (rq1 < rq2) {
1da177e4
LT
1988 spin_lock(&rq1->lock);
1989 spin_lock(&rq2->lock);
1990 } else {
1991 spin_lock(&rq2->lock);
1992 spin_lock(&rq1->lock);
1993 }
1994 }
1995}
1996
1997/*
1998 * double_rq_unlock - safely unlock two runqueues
1999 *
2000 * Note this does not restore interrupts like task_rq_unlock,
2001 * you need to do so manually after calling.
2002 */
70b97a7f 2003static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
1da177e4
LT
2004 __releases(rq1->lock)
2005 __releases(rq2->lock)
2006{
2007 spin_unlock(&rq1->lock);
2008 if (rq1 != rq2)
2009 spin_unlock(&rq2->lock);
2010 else
2011 __release(rq2->lock);
2012}
2013
2014/*
2015 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2016 */
70b97a7f 2017static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
1da177e4
LT
2018 __releases(this_rq->lock)
2019 __acquires(busiest->lock)
2020 __acquires(this_rq->lock)
2021{
054b9108
KK
2022 if (unlikely(!irqs_disabled())) {
2023 /* printk() doesn't work good under rq->lock */
2024 spin_unlock(&this_rq->lock);
2025 BUG_ON(1);
2026 }
1da177e4 2027 if (unlikely(!spin_trylock(&busiest->lock))) {
c96d145e 2028 if (busiest < this_rq) {
1da177e4
LT
2029 spin_unlock(&this_rq->lock);
2030 spin_lock(&busiest->lock);
2031 spin_lock(&this_rq->lock);
2032 } else
2033 spin_lock(&busiest->lock);
2034 }
2035}
2036
1da177e4
LT
2037/*
2038 * If dest_cpu is allowed for this process, migrate the task to it.
2039 * This is accomplished by forcing the cpu_allowed mask to only
2040 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2041 * the cpu_allowed mask is restored.
2042 */
36c8b586 2043static void sched_migrate_task(struct task_struct *p, int dest_cpu)
1da177e4 2044{
70b97a7f 2045 struct migration_req req;
1da177e4 2046 unsigned long flags;
70b97a7f 2047 struct rq *rq;
1da177e4
LT
2048
2049 rq = task_rq_lock(p, &flags);
2050 if (!cpu_isset(dest_cpu, p->cpus_allowed)
2051 || unlikely(cpu_is_offline(dest_cpu)))
2052 goto out;
2053
2054 /* force the process onto the specified CPU */
2055 if (migrate_task(p, dest_cpu, &req)) {
2056 /* Need to wait for migration thread (might exit: take ref). */
2057 struct task_struct *mt = rq->migration_thread;
36c8b586 2058
1da177e4
LT
2059 get_task_struct(mt);
2060 task_rq_unlock(rq, &flags);
2061 wake_up_process(mt);
2062 put_task_struct(mt);
2063 wait_for_completion(&req.done);
36c8b586 2064
1da177e4
LT
2065 return;
2066 }
2067out:
2068 task_rq_unlock(rq, &flags);
2069}
2070
2071/*
476d139c
NP
2072 * sched_exec - execve() is a valuable balancing opportunity, because at
2073 * this point the task has the smallest effective memory and cache footprint.
1da177e4
LT
2074 */
2075void sched_exec(void)
2076{
1da177e4 2077 int new_cpu, this_cpu = get_cpu();
476d139c 2078 new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
1da177e4 2079 put_cpu();
476d139c
NP
2080 if (new_cpu != this_cpu)
2081 sched_migrate_task(current, new_cpu);
1da177e4
LT
2082}
2083
2084/*
2085 * pull_task - move a task from a remote runqueue to the local runqueue.
2086 * Both runqueues must be locked.
2087 */
70b97a7f
IM
2088static void pull_task(struct rq *src_rq, struct prio_array *src_array,
2089 struct task_struct *p, struct rq *this_rq,
2090 struct prio_array *this_array, int this_cpu)
1da177e4
LT
2091{
2092 dequeue_task(p, src_array);
2dd73a4f 2093 dec_nr_running(p, src_rq);
1da177e4 2094 set_task_cpu(p, this_cpu);
2dd73a4f 2095 inc_nr_running(p, this_rq);
1da177e4 2096 enqueue_task(p, this_array);
b18ec803
MG
2097 p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
2098 + this_rq->most_recent_timestamp;
1da177e4
LT
2099 /*
2100 * Note that idle threads have a prio of MAX_PRIO, for this test
2101 * to be always true for them.
2102 */
2103 if (TASK_PREEMPTS_CURR(p, this_rq))
2104 resched_task(this_rq->curr);
2105}
2106
2107/*
2108 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2109 */
858119e1 2110static
70b97a7f 2111int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
95cdf3b7
IM
2112 struct sched_domain *sd, enum idle_type idle,
2113 int *all_pinned)
1da177e4
LT
2114{
2115 /*
2116 * We do not migrate tasks that are:
2117 * 1) running (obviously), or
2118 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2119 * 3) are cache-hot on their current CPU.
2120 */
1da177e4
LT
2121 if (!cpu_isset(this_cpu, p->cpus_allowed))
2122 return 0;
81026794
NP
2123 *all_pinned = 0;
2124
2125 if (task_running(rq, p))
2126 return 0;
1da177e4
LT
2127
2128 /*
2129 * Aggressive migration if:
cafb20c1 2130 * 1) task is cache cold, or
1da177e4
LT
2131 * 2) too many balance attempts have failed.
2132 */
2133
b18ec803
MG
2134 if (sd->nr_balance_failed > sd->cache_nice_tries) {
2135#ifdef CONFIG_SCHEDSTATS
2136 if (task_hot(p, rq->most_recent_timestamp, sd))
2137 schedstat_inc(sd, lb_hot_gained[idle]);
2138#endif
1da177e4 2139 return 1;
b18ec803 2140 }
1da177e4 2141
b18ec803 2142 if (task_hot(p, rq->most_recent_timestamp, sd))
81026794 2143 return 0;
1da177e4
LT
2144 return 1;
2145}
2146
615052dc 2147#define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
48f24c4d 2148
1da177e4 2149/*
2dd73a4f
PW
2150 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2151 * load from busiest to this_rq, as part of a balancing operation within
2152 * "domain". Returns the number of tasks moved.
1da177e4
LT
2153 *
2154 * Called with both runqueues locked.
2155 */
70b97a7f 2156static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
2dd73a4f
PW
2157 unsigned long max_nr_move, unsigned long max_load_move,
2158 struct sched_domain *sd, enum idle_type idle,
2159 int *all_pinned)
1da177e4 2160{
48f24c4d
IM
2161 int idx, pulled = 0, pinned = 0, this_best_prio, best_prio,
2162 best_prio_seen, skip_for_load;
70b97a7f 2163 struct prio_array *array, *dst_array;
1da177e4 2164 struct list_head *head, *curr;
36c8b586 2165 struct task_struct *tmp;
2dd73a4f 2166 long rem_load_move;
1da177e4 2167
2dd73a4f 2168 if (max_nr_move == 0 || max_load_move == 0)
1da177e4
LT
2169 goto out;
2170
2dd73a4f 2171 rem_load_move = max_load_move;
81026794 2172 pinned = 1;
615052dc 2173 this_best_prio = rq_best_prio(this_rq);
48f24c4d 2174 best_prio = rq_best_prio(busiest);
615052dc
PW
2175 /*
2176 * Enable handling of the case where there is more than one task
2177 * with the best priority. If the current running task is one
48f24c4d 2178 * of those with prio==best_prio we know it won't be moved
615052dc
PW
2179 * and therefore it's safe to override the skip (based on load) of
2180 * any task we find with that prio.
2181 */
48f24c4d 2182 best_prio_seen = best_prio == busiest->curr->prio;
81026794 2183
1da177e4
LT
2184 /*
2185 * We first consider expired tasks. Those will likely not be
2186 * executed in the near future, and they are most likely to
2187 * be cache-cold, thus switching CPUs has the least effect
2188 * on them.
2189 */
2190 if (busiest->expired->nr_active) {
2191 array = busiest->expired;
2192 dst_array = this_rq->expired;
2193 } else {
2194 array = busiest->active;
2195 dst_array = this_rq->active;
2196 }
2197
2198new_array:
2199 /* Start searching at priority 0: */
2200 idx = 0;
2201skip_bitmap:
2202 if (!idx)
2203 idx = sched_find_first_bit(array->bitmap);
2204 else
2205 idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
2206 if (idx >= MAX_PRIO) {
2207 if (array == busiest->expired && busiest->active->nr_active) {
2208 array = busiest->active;
2209 dst_array = this_rq->active;
2210 goto new_array;
2211 }
2212 goto out;
2213 }
2214
2215 head = array->queue + idx;
2216 curr = head->prev;
2217skip_queue:
36c8b586 2218 tmp = list_entry(curr, struct task_struct, run_list);
1da177e4
LT
2219
2220 curr = curr->prev;
2221
50ddd969
PW
2222 /*
2223 * To help distribute high priority tasks accross CPUs we don't
2224 * skip a task if it will be the highest priority task (i.e. smallest
2225 * prio value) on its new queue regardless of its load weight
2226 */
615052dc
PW
2227 skip_for_load = tmp->load_weight > rem_load_move;
2228 if (skip_for_load && idx < this_best_prio)
48f24c4d 2229 skip_for_load = !best_prio_seen && idx == best_prio;
615052dc 2230 if (skip_for_load ||
2dd73a4f 2231 !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
48f24c4d
IM
2232
2233 best_prio_seen |= idx == best_prio;
1da177e4
LT
2234 if (curr != head)
2235 goto skip_queue;
2236 idx++;
2237 goto skip_bitmap;
2238 }
2239
1da177e4
LT
2240 pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
2241 pulled++;
2dd73a4f 2242 rem_load_move -= tmp->load_weight;
1da177e4 2243
2dd73a4f
PW
2244 /*
2245 * We only want to steal up to the prescribed number of tasks
2246 * and the prescribed amount of weighted load.
2247 */
2248 if (pulled < max_nr_move && rem_load_move > 0) {
615052dc
PW
2249 if (idx < this_best_prio)
2250 this_best_prio = idx;
1da177e4
LT
2251 if (curr != head)
2252 goto skip_queue;
2253 idx++;
2254 goto skip_bitmap;
2255 }
2256out:
2257 /*
2258 * Right now, this is the only place pull_task() is called,
2259 * so we can safely collect pull_task() stats here rather than
2260 * inside pull_task().
2261 */
2262 schedstat_add(sd, lb_gained[idle], pulled);
81026794
NP
2263
2264 if (all_pinned)
2265 *all_pinned = pinned;
1da177e4
LT
2266 return pulled;
2267}
2268
2269/*
2270 * find_busiest_group finds and returns the busiest CPU group within the
48f24c4d
IM
2271 * domain. It calculates and returns the amount of weighted load which
2272 * should be moved to restore balance via the imbalance parameter.
1da177e4
LT
2273 */
2274static struct sched_group *
2275find_busiest_group(struct sched_domain *sd, int this_cpu,
0a2966b4 2276 unsigned long *imbalance, enum idle_type idle, int *sd_idle,
783609c6 2277 cpumask_t *cpus, int *balance)
1da177e4
LT
2278{
2279 struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
2280 unsigned long max_load, avg_load, total_load, this_load, total_pwr;
0c117f1b 2281 unsigned long max_pull;
2dd73a4f
PW
2282 unsigned long busiest_load_per_task, busiest_nr_running;
2283 unsigned long this_load_per_task, this_nr_running;
7897986b 2284 int load_idx;
5c45bf27
SS
2285#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2286 int power_savings_balance = 1;
2287 unsigned long leader_nr_running = 0, min_load_per_task = 0;
2288 unsigned long min_nr_running = ULONG_MAX;
2289 struct sched_group *group_min = NULL, *group_leader = NULL;
2290#endif
1da177e4
LT
2291
2292 max_load = this_load = total_load = total_pwr = 0;
2dd73a4f
PW
2293 busiest_load_per_task = busiest_nr_running = 0;
2294 this_load_per_task = this_nr_running = 0;
7897986b
NP
2295 if (idle == NOT_IDLE)
2296 load_idx = sd->busy_idx;
2297 else if (idle == NEWLY_IDLE)
2298 load_idx = sd->newidle_idx;
2299 else
2300 load_idx = sd->idle_idx;
1da177e4
LT
2301
2302 do {
5c45bf27 2303 unsigned long load, group_capacity;
1da177e4
LT
2304 int local_group;
2305 int i;
783609c6 2306 unsigned int balance_cpu = -1, first_idle_cpu = 0;
2dd73a4f 2307 unsigned long sum_nr_running, sum_weighted_load;
1da177e4
LT
2308
2309 local_group = cpu_isset(this_cpu, group->cpumask);
2310
783609c6
SS
2311 if (local_group)
2312 balance_cpu = first_cpu(group->cpumask);
2313
1da177e4 2314 /* Tally up the load of all CPUs in the group */
2dd73a4f 2315 sum_weighted_load = sum_nr_running = avg_load = 0;
1da177e4
LT
2316
2317 for_each_cpu_mask(i, group->cpumask) {
0a2966b4
CL
2318 struct rq *rq;
2319
2320 if (!cpu_isset(i, *cpus))
2321 continue;
2322
2323 rq = cpu_rq(i);
2dd73a4f 2324
5969fe06
NP
2325 if (*sd_idle && !idle_cpu(i))
2326 *sd_idle = 0;
2327
1da177e4 2328 /* Bias balancing toward cpus of our domain */
783609c6
SS
2329 if (local_group) {
2330 if (idle_cpu(i) && !first_idle_cpu) {
2331 first_idle_cpu = 1;
2332 balance_cpu = i;
2333 }
2334
a2000572 2335 load = target_load(i, load_idx);
783609c6 2336 } else
a2000572 2337 load = source_load(i, load_idx);
1da177e4
LT
2338
2339 avg_load += load;
2dd73a4f
PW
2340 sum_nr_running += rq->nr_running;
2341 sum_weighted_load += rq->raw_weighted_load;
1da177e4
LT
2342 }
2343
783609c6
SS
2344 /*
2345 * First idle cpu or the first cpu(busiest) in this sched group
2346 * is eligible for doing load balancing at this and above
2347 * domains.
2348 */
2349 if (local_group && balance_cpu != this_cpu && balance) {
2350 *balance = 0;
2351 goto ret;
2352 }
2353
1da177e4
LT
2354 total_load += avg_load;
2355 total_pwr += group->cpu_power;
2356
2357 /* Adjust by relative CPU power of the group */
2358 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
2359
5c45bf27
SS
2360 group_capacity = group->cpu_power / SCHED_LOAD_SCALE;
2361
1da177e4
LT
2362 if (local_group) {
2363 this_load = avg_load;
2364 this = group;
2dd73a4f
PW
2365 this_nr_running = sum_nr_running;
2366 this_load_per_task = sum_weighted_load;
2367 } else if (avg_load > max_load &&
5c45bf27 2368 sum_nr_running > group_capacity) {
1da177e4
LT
2369 max_load = avg_load;
2370 busiest = group;
2dd73a4f
PW
2371 busiest_nr_running = sum_nr_running;
2372 busiest_load_per_task = sum_weighted_load;
1da177e4 2373 }
5c45bf27
SS
2374
2375#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2376 /*
2377 * Busy processors will not participate in power savings
2378 * balance.
2379 */
2380 if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2381 goto group_next;
2382
2383 /*
2384 * If the local group is idle or completely loaded
2385 * no need to do power savings balance at this domain
2386 */
2387 if (local_group && (this_nr_running >= group_capacity ||
2388 !this_nr_running))
2389 power_savings_balance = 0;
2390
2391 /*
2392 * If a group is already running at full capacity or idle,
2393 * don't include that group in power savings calculations
2394 */
2395 if (!power_savings_balance || sum_nr_running >= group_capacity
2396 || !sum_nr_running)
2397 goto group_next;
2398
2399 /*
2400 * Calculate the group which has the least non-idle load.
2401 * This is the group from where we need to pick up the load
2402 * for saving power
2403 */
2404 if ((sum_nr_running < min_nr_running) ||
2405 (sum_nr_running == min_nr_running &&
2406 first_cpu(group->cpumask) <
2407 first_cpu(group_min->cpumask))) {
2408 group_min = group;
2409 min_nr_running = sum_nr_running;
2410 min_load_per_task = sum_weighted_load /
2411 sum_nr_running;
2412 }
2413
2414 /*
2415 * Calculate the group which is almost near its
2416 * capacity but still has some space to pick up some load
2417 * from other group and save more power
2418 */
48f24c4d 2419 if (sum_nr_running <= group_capacity - 1) {
5c45bf27
SS
2420 if (sum_nr_running > leader_nr_running ||
2421 (sum_nr_running == leader_nr_running &&
2422 first_cpu(group->cpumask) >
2423 first_cpu(group_leader->cpumask))) {
2424 group_leader = group;
2425 leader_nr_running = sum_nr_running;
2426 }
48f24c4d 2427 }
5c45bf27
SS
2428group_next:
2429#endif
1da177e4
LT
2430 group = group->next;
2431 } while (group != sd->groups);
2432
2dd73a4f 2433 if (!busiest || this_load >= max_load || busiest_nr_running == 0)
1da177e4
LT
2434 goto out_balanced;
2435
2436 avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
2437
2438 if (this_load >= avg_load ||
2439 100*max_load <= sd->imbalance_pct*this_load)
2440 goto out_balanced;
2441
2dd73a4f 2442 busiest_load_per_task /= busiest_nr_running;
1da177e4
LT
2443 /*
2444 * We're trying to get all the cpus to the average_load, so we don't
2445 * want to push ourselves above the average load, nor do we wish to
2446 * reduce the max loaded cpu below the average load, as either of these
2447 * actions would just result in more rebalancing later, and ping-pong
2448 * tasks around. Thus we look for the minimum possible imbalance.
2449 * Negative imbalances (*we* are more loaded than anyone else) will
2450 * be counted as no imbalance for these purposes -- we can't fix that
2451 * by pulling tasks to us. Be careful of negative numbers as they'll
2452 * appear as very large values with unsigned longs.
2453 */
2dd73a4f
PW
2454 if (max_load <= busiest_load_per_task)
2455 goto out_balanced;
2456
2457 /*
2458 * In the presence of smp nice balancing, certain scenarios can have
2459 * max load less than avg load(as we skip the groups at or below
2460 * its cpu_power, while calculating max_load..)
2461 */
2462 if (max_load < avg_load) {
2463 *imbalance = 0;
2464 goto small_imbalance;
2465 }
0c117f1b
SS
2466
2467 /* Don't want to pull so many tasks that a group would go idle */
2dd73a4f 2468 max_pull = min(max_load - avg_load, max_load - busiest_load_per_task);
0c117f1b 2469
1da177e4 2470 /* How much load to actually move to equalise the imbalance */
0c117f1b 2471 *imbalance = min(max_pull * busiest->cpu_power,
1da177e4
LT
2472 (avg_load - this_load) * this->cpu_power)
2473 / SCHED_LOAD_SCALE;
2474
2dd73a4f
PW
2475 /*
2476 * if *imbalance is less than the average load per runnable task
2477 * there is no gaurantee that any tasks will be moved so we'll have
2478 * a think about bumping its value to force at least one task to be
2479 * moved
2480 */
2481 if (*imbalance < busiest_load_per_task) {
48f24c4d 2482 unsigned long tmp, pwr_now, pwr_move;
2dd73a4f
PW
2483 unsigned int imbn;
2484
2485small_imbalance:
2486 pwr_move = pwr_now = 0;
2487 imbn = 2;
2488 if (this_nr_running) {
2489 this_load_per_task /= this_nr_running;
2490 if (busiest_load_per_task > this_load_per_task)
2491 imbn = 1;
2492 } else
2493 this_load_per_task = SCHED_LOAD_SCALE;
1da177e4 2494
2dd73a4f
PW
2495 if (max_load - this_load >= busiest_load_per_task * imbn) {
2496 *imbalance = busiest_load_per_task;
1da177e4
LT
2497 return busiest;
2498 }
2499
2500 /*
2501 * OK, we don't have enough imbalance to justify moving tasks,
2502 * however we may be able to increase total CPU power used by
2503 * moving them.
2504 */
2505
2dd73a4f
PW
2506 pwr_now += busiest->cpu_power *
2507 min(busiest_load_per_task, max_load);
2508 pwr_now += this->cpu_power *
2509 min(this_load_per_task, this_load);
1da177e4
LT
2510 pwr_now /= SCHED_LOAD_SCALE;
2511
2512 /* Amount of load we'd subtract */
33859f7f
MOS
2513 tmp = busiest_load_per_task * SCHED_LOAD_SCALE /
2514 busiest->cpu_power;
1da177e4 2515 if (max_load > tmp)
2dd73a4f
PW
2516 pwr_move += busiest->cpu_power *
2517 min(busiest_load_per_task, max_load - tmp);
1da177e4
LT
2518
2519 /* Amount of load we'd add */
33859f7f
MOS
2520 if (max_load * busiest->cpu_power <
2521 busiest_load_per_task * SCHED_LOAD_SCALE)
2522 tmp = max_load * busiest->cpu_power / this->cpu_power;
1da177e4 2523 else
33859f7f
MOS
2524 tmp = busiest_load_per_task * SCHED_LOAD_SCALE /
2525 this->cpu_power;
2526 pwr_move += this->cpu_power *
2527 min(this_load_per_task, this_load + tmp);
1da177e4
LT
2528 pwr_move /= SCHED_LOAD_SCALE;
2529
2530 /* Move if we gain throughput */
2531 if (pwr_move <= pwr_now)
2532 goto out_balanced;
2533
2dd73a4f 2534 *imbalance = busiest_load_per_task;
1da177e4
LT
2535 }
2536
1da177e4
LT
2537 return busiest;
2538
2539out_balanced:
5c45bf27
SS
2540#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2541 if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
2542 goto ret;
1da177e4 2543
5c45bf27
SS
2544 if (this == group_leader && group_leader != group_min) {
2545 *imbalance = min_load_per_task;
2546 return group_min;
2547 }
5c45bf27 2548#endif
783609c6 2549ret:
1da177e4
LT
2550 *imbalance = 0;
2551 return NULL;
2552}
2553
2554/*
2555 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2556 */
70b97a7f 2557static struct rq *
48f24c4d 2558find_busiest_queue(struct sched_group *group, enum idle_type idle,
0a2966b4 2559 unsigned long imbalance, cpumask_t *cpus)
1da177e4 2560{
70b97a7f 2561 struct rq *busiest = NULL, *rq;
2dd73a4f 2562 unsigned long max_load = 0;
1da177e4
LT
2563 int i;
2564
2565 for_each_cpu_mask(i, group->cpumask) {
0a2966b4
CL
2566
2567 if (!cpu_isset(i, *cpus))
2568 continue;
2569
48f24c4d 2570 rq = cpu_rq(i);
2dd73a4f 2571
48f24c4d 2572 if (rq->nr_running == 1 && rq->raw_weighted_load > imbalance)
2dd73a4f 2573 continue;
1da177e4 2574
48f24c4d
IM
2575 if (rq->raw_weighted_load > max_load) {
2576 max_load = rq->raw_weighted_load;
2577 busiest = rq;
1da177e4
LT
2578 }
2579 }
2580
2581 return busiest;
2582}
2583
77391d71
NP
2584/*
2585 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2586 * so long as it is large enough.
2587 */
2588#define MAX_PINNED_INTERVAL 512
2589
48f24c4d
IM
2590static inline unsigned long minus_1_or_zero(unsigned long n)
2591{
2592 return n > 0 ? n - 1 : 0;
2593}
2594
1da177e4
LT
2595/*
2596 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2597 * tasks if there is an imbalance.
1da177e4 2598 */
70b97a7f 2599static int load_balance(int this_cpu, struct rq *this_rq,
783609c6
SS
2600 struct sched_domain *sd, enum idle_type idle,
2601 int *balance)
1da177e4 2602{
48f24c4d 2603 int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
1da177e4 2604 struct sched_group *group;
1da177e4 2605 unsigned long imbalance;
70b97a7f 2606 struct rq *busiest;
0a2966b4 2607 cpumask_t cpus = CPU_MASK_ALL;
fe2eea3f 2608 unsigned long flags;
5969fe06 2609
89c4710e
SS
2610 /*
2611 * When power savings policy is enabled for the parent domain, idle
2612 * sibling can pick up load irrespective of busy siblings. In this case,
2613 * let the state of idle sibling percolate up as IDLE, instead of
2614 * portraying it as NOT_IDLE.
2615 */
5c45bf27 2616 if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
89c4710e 2617 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06 2618 sd_idle = 1;
1da177e4 2619
1da177e4
LT
2620 schedstat_inc(sd, lb_cnt[idle]);
2621
0a2966b4
CL
2622redo:
2623 group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
783609c6
SS
2624 &cpus, balance);
2625
06066714 2626 if (*balance == 0)
783609c6 2627 goto out_balanced;
783609c6 2628
1da177e4
LT
2629 if (!group) {
2630 schedstat_inc(sd, lb_nobusyg[idle]);
2631 goto out_balanced;
2632 }
2633
0a2966b4 2634 busiest = find_busiest_queue(group, idle, imbalance, &cpus);
1da177e4
LT
2635 if (!busiest) {
2636 schedstat_inc(sd, lb_nobusyq[idle]);
2637 goto out_balanced;
2638 }
2639
db935dbd 2640 BUG_ON(busiest == this_rq);
1da177e4
LT
2641
2642 schedstat_add(sd, lb_imbalance[idle], imbalance);
2643
2644 nr_moved = 0;
2645 if (busiest->nr_running > 1) {
2646 /*
2647 * Attempt to move tasks. If find_busiest_group has found
2648 * an imbalance but busiest->nr_running <= 1, the group is
2649 * still unbalanced. nr_moved simply stays zero, so it is
2650 * correctly treated as an imbalance.
2651 */
fe2eea3f 2652 local_irq_save(flags);
e17224bf 2653 double_rq_lock(this_rq, busiest);
1da177e4 2654 nr_moved = move_tasks(this_rq, this_cpu, busiest,
48f24c4d
IM
2655 minus_1_or_zero(busiest->nr_running),
2656 imbalance, sd, idle, &all_pinned);
e17224bf 2657 double_rq_unlock(this_rq, busiest);
fe2eea3f 2658 local_irq_restore(flags);
81026794
NP
2659
2660 /* All tasks on this runqueue were pinned by CPU affinity */
0a2966b4
CL
2661 if (unlikely(all_pinned)) {
2662 cpu_clear(cpu_of(busiest), cpus);
2663 if (!cpus_empty(cpus))
2664 goto redo;
81026794 2665 goto out_balanced;
0a2966b4 2666 }
1da177e4 2667 }
81026794 2668
1da177e4
LT
2669 if (!nr_moved) {
2670 schedstat_inc(sd, lb_failed[idle]);
2671 sd->nr_balance_failed++;
2672
2673 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
1da177e4 2674
fe2eea3f 2675 spin_lock_irqsave(&busiest->lock, flags);
fa3b6ddc
SS
2676
2677 /* don't kick the migration_thread, if the curr
2678 * task on busiest cpu can't be moved to this_cpu
2679 */
2680 if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) {
fe2eea3f 2681 spin_unlock_irqrestore(&busiest->lock, flags);
fa3b6ddc
SS
2682 all_pinned = 1;
2683 goto out_one_pinned;
2684 }
2685
1da177e4
LT
2686 if (!busiest->active_balance) {
2687 busiest->active_balance = 1;
2688 busiest->push_cpu = this_cpu;
81026794 2689 active_balance = 1;
1da177e4 2690 }
fe2eea3f 2691 spin_unlock_irqrestore(&busiest->lock, flags);
81026794 2692 if (active_balance)
1da177e4
LT
2693 wake_up_process(busiest->migration_thread);
2694
2695 /*
2696 * We've kicked active balancing, reset the failure
2697 * counter.
2698 */
39507451 2699 sd->nr_balance_failed = sd->cache_nice_tries+1;
1da177e4 2700 }
81026794 2701 } else
1da177e4
LT
2702 sd->nr_balance_failed = 0;
2703
81026794 2704 if (likely(!active_balance)) {
1da177e4
LT
2705 /* We were unbalanced, so reset the balancing interval */
2706 sd->balance_interval = sd->min_interval;
81026794
NP
2707 } else {
2708 /*
2709 * If we've begun active balancing, start to back off. This
2710 * case may not be covered by the all_pinned logic if there
2711 * is only 1 task on the busy runqueue (because we don't call
2712 * move_tasks).
2713 */
2714 if (sd->balance_interval < sd->max_interval)
2715 sd->balance_interval *= 2;
1da177e4
LT
2716 }
2717
5c45bf27 2718 if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
89c4710e 2719 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06 2720 return -1;
1da177e4
LT
2721 return nr_moved;
2722
2723out_balanced:
1da177e4
LT
2724 schedstat_inc(sd, lb_balanced[idle]);
2725
16cfb1c0 2726 sd->nr_balance_failed = 0;
fa3b6ddc
SS
2727
2728out_one_pinned:
1da177e4 2729 /* tune up the balancing interval */
77391d71
NP
2730 if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
2731 (sd->balance_interval < sd->max_interval))
1da177e4
LT
2732 sd->balance_interval *= 2;
2733
48f24c4d 2734 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
89c4710e 2735 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06 2736 return -1;
1da177e4
LT
2737 return 0;
2738}
2739
2740/*
2741 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2742 * tasks if there is an imbalance.
2743 *
2744 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2745 * this_rq is locked.
2746 */
48f24c4d 2747static int
70b97a7f 2748load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
1da177e4
LT
2749{
2750 struct sched_group *group;
70b97a7f 2751 struct rq *busiest = NULL;
1da177e4
LT
2752 unsigned long imbalance;
2753 int nr_moved = 0;
5969fe06 2754 int sd_idle = 0;
0a2966b4 2755 cpumask_t cpus = CPU_MASK_ALL;
5969fe06 2756
89c4710e
SS
2757 /*
2758 * When power savings policy is enabled for the parent domain, idle
2759 * sibling can pick up load irrespective of busy siblings. In this case,
2760 * let the state of idle sibling percolate up as IDLE, instead of
2761 * portraying it as NOT_IDLE.
2762 */
2763 if (sd->flags & SD_SHARE_CPUPOWER &&
2764 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06 2765 sd_idle = 1;
1da177e4
LT
2766
2767 schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
0a2966b4
CL
2768redo:
2769 group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE,
783609c6 2770 &sd_idle, &cpus, NULL);
1da177e4 2771 if (!group) {
1da177e4 2772 schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
16cfb1c0 2773 goto out_balanced;
1da177e4
LT
2774 }
2775
0a2966b4
CL
2776 busiest = find_busiest_queue(group, NEWLY_IDLE, imbalance,
2777 &cpus);
db935dbd 2778 if (!busiest) {
1da177e4 2779 schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
16cfb1c0 2780 goto out_balanced;
1da177e4
LT
2781 }
2782
db935dbd
NP
2783 BUG_ON(busiest == this_rq);
2784
1da177e4 2785 schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
d6d5cfaf
NP
2786
2787 nr_moved = 0;
2788 if (busiest->nr_running > 1) {
2789 /* Attempt to move tasks */
2790 double_lock_balance(this_rq, busiest);
2791 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2dd73a4f 2792 minus_1_or_zero(busiest->nr_running),
81026794 2793 imbalance, sd, NEWLY_IDLE, NULL);
d6d5cfaf 2794 spin_unlock(&busiest->lock);
0a2966b4
CL
2795
2796 if (!nr_moved) {
2797 cpu_clear(cpu_of(busiest), cpus);
2798 if (!cpus_empty(cpus))
2799 goto redo;
2800 }
d6d5cfaf
NP
2801 }
2802
5969fe06 2803 if (!nr_moved) {
1da177e4 2804 schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
89c4710e
SS
2805 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
2806 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06
NP
2807 return -1;
2808 } else
16cfb1c0 2809 sd->nr_balance_failed = 0;
1da177e4 2810
1da177e4 2811 return nr_moved;
16cfb1c0
NP
2812
2813out_balanced:
2814 schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
48f24c4d 2815 if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
89c4710e 2816 !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
5969fe06 2817 return -1;
16cfb1c0 2818 sd->nr_balance_failed = 0;
48f24c4d 2819
16cfb1c0 2820 return 0;
1da177e4
LT
2821}
2822
2823/*
2824 * idle_balance is called by schedule() if this_cpu is about to become
2825 * idle. Attempts to pull tasks from other CPUs.
2826 */
70b97a7f 2827static void idle_balance(int this_cpu, struct rq *this_rq)
1da177e4
LT
2828{
2829 struct sched_domain *sd;
1bd77f2d
CL
2830 int pulled_task = 0;
2831 unsigned long next_balance = jiffies + 60 * HZ;
1da177e4
LT
2832
2833 for_each_domain(this_cpu, sd) {
2834 if (sd->flags & SD_BALANCE_NEWIDLE) {
48f24c4d 2835 /* If we've pulled tasks over stop searching: */
1bd77f2d
CL
2836 pulled_task = load_balance_newidle(this_cpu,
2837 this_rq, sd);
2838 if (time_after(next_balance,
2839 sd->last_balance + sd->balance_interval))
2840 next_balance = sd->last_balance
2841 + sd->balance_interval;
2842 if (pulled_task)
1da177e4 2843 break;
1da177e4
LT
2844 }
2845 }
1bd77f2d
CL
2846 if (!pulled_task)
2847 /*
2848 * We are going idle. next_balance may be set based on
2849 * a busy processor. So reset next_balance.
2850 */
2851 this_rq->next_balance = next_balance;
1da177e4
LT
2852}
2853
2854/*
2855 * active_load_balance is run by migration threads. It pushes running tasks
2856 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2857 * running on each physical CPU where possible, and avoids physical /
2858 * logical imbalances.
2859 *
2860 * Called with busiest_rq locked.
2861 */
70b97a7f 2862static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
1da177e4 2863{
39507451 2864 int target_cpu = busiest_rq->push_cpu;
70b97a7f
IM
2865 struct sched_domain *sd;
2866 struct rq *target_rq;
39507451 2867
48f24c4d 2868 /* Is there any task to move? */
39507451 2869 if (busiest_rq->nr_running <= 1)
39507451
NP
2870 return;
2871
2872 target_rq = cpu_rq(target_cpu);
1da177e4
LT
2873
2874 /*
39507451
NP
2875 * This condition is "impossible", if it occurs
2876 * we need to fix it. Originally reported by
2877 * Bjorn Helgaas on a 128-cpu setup.
1da177e4 2878 */
39507451 2879 BUG_ON(busiest_rq == target_rq);
1da177e4 2880
39507451
NP
2881 /* move a task from busiest_rq to target_rq */
2882 double_lock_balance(busiest_rq, target_rq);
2883
2884 /* Search for an sd spanning us and the target CPU. */
c96d145e 2885 for_each_domain(target_cpu, sd) {
39507451 2886 if ((sd->flags & SD_LOAD_BALANCE) &&
48f24c4d 2887 cpu_isset(busiest_cpu, sd->span))
39507451 2888 break;
c96d145e 2889 }
39507451 2890
48f24c4d
IM
2891 if (likely(sd)) {
2892 schedstat_inc(sd, alb_cnt);
39507451 2893
48f24c4d
IM
2894 if (move_tasks(target_rq, target_cpu, busiest_rq, 1,
2895 RTPRIO_TO_LOAD_WEIGHT(100), sd, SCHED_IDLE,
2896 NULL))
2897 schedstat_inc(sd, alb_pushed);
2898 else
2899 schedstat_inc(sd, alb_failed);
2900 }
39507451 2901 spin_unlock(&target_rq->lock);
1da177e4
LT
2902}
2903
7835b98b 2904static void update_load(struct rq *this_rq)
1da177e4 2905{
7835b98b 2906 unsigned long this_load;
ff91691b 2907 unsigned int i, scale;
1da177e4 2908
2dd73a4f 2909 this_load = this_rq->raw_weighted_load;
48f24c4d
IM
2910
2911 /* Update our load: */
ff91691b 2912 for (i = 0, scale = 1; i < 3; i++, scale += scale) {
48f24c4d
IM
2913 unsigned long old_load, new_load;
2914
ff91691b
NP
2915 /* scale is effectively 1 << i now, and >> i divides by scale */
2916
7897986b 2917 old_load = this_rq->cpu_load[i];
48f24c4d 2918 new_load = this_load;
7897986b
NP
2919 /*
2920 * Round up the averaging division if load is increasing. This
2921 * prevents us from getting stuck on 9 if the load is 10, for
2922 * example.
2923 */
2924 if (new_load > old_load)
2925 new_load += scale-1;
ff91691b 2926 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
7897986b 2927 }
7835b98b
CL
2928}
2929
2930/*
c9819f45 2931 * run_rebalance_domains is triggered when needed from the scheduler tick.
7835b98b
CL
2932 *
2933 * It checks each scheduling domain to see if it is due to be balanced,
2934 * and initiates a balancing operation if so.
2935 *
2936 * Balancing parameters are set up in arch_init_sched_domains.
2937 */
08c183f3 2938static DEFINE_SPINLOCK(balancing);
7835b98b 2939
c9819f45 2940static void run_rebalance_domains(struct softirq_action *h)
7835b98b 2941{
783609c6 2942 int this_cpu = smp_processor_id(), balance = 1;
c9819f45 2943 struct rq *this_rq = cpu_rq(this_cpu);
7835b98b
CL
2944 unsigned long interval;
2945 struct sched_domain *sd;
e418e1c2
CL
2946 /*
2947 * We are idle if there are no processes running. This
2948 * is valid even if we are the idle process (SMT).
2949 */
2950 enum idle_type idle = !this_rq->nr_running ?
2951 SCHED_IDLE : NOT_IDLE;
c9819f45
CL
2952 /* Earliest time when we have to call run_rebalance_domains again */
2953 unsigned long next_balance = jiffies + 60*HZ;
1da177e4
LT
2954
2955 for_each_domain(this_cpu, sd) {
1da177e4
LT
2956 if (!(sd->flags & SD_LOAD_BALANCE))
2957 continue;
2958
2959 interval = sd->balance_interval;
2960 if (idle != SCHED_IDLE)
2961 interval *= sd->busy_factor;
2962
2963 /* scale ms to jiffies */
2964 interval = msecs_to_jiffies(interval);
2965 if (unlikely(!interval))
2966 interval = 1;
2967
08c183f3
CL
2968 if (sd->flags & SD_SERIALIZE) {
2969 if (!spin_trylock(&balancing))
2970 goto out;
2971 }
2972
c9819f45 2973 if (time_after_eq(jiffies, sd->last_balance + interval)) {
783609c6 2974 if (load_balance(this_cpu, this_rq, sd, idle, &balance)) {
fa3b6ddc
SS
2975 /*
2976 * We've pulled tasks over so either we're no
5969fe06
NP
2977 * longer idle, or one of our SMT siblings is
2978 * not idle.
2979 */
1da177e4
LT
2980 idle = NOT_IDLE;
2981 }
1bd77f2d 2982 sd->last_balance = jiffies;
1da177e4 2983 }
08c183f3
CL
2984 if (sd->flags & SD_SERIALIZE)
2985 spin_unlock(&balancing);
2986out:
c9819f45
CL
2987 if (time_after(next_balance, sd->last_balance + interval))
2988 next_balance = sd->last_balance + interval;
783609c6
SS
2989
2990 /*
2991 * Stop the load balance at this level. There is another
2992 * CPU in our sched group which is doing load balancing more
2993 * actively.
2994 */
2995 if (!balance)
2996 break;
1da177e4 2997 }
c9819f45 2998 this_rq->next_balance = next_balance;
1da177e4
LT
2999}
3000#else
3001/*
3002 * on UP we do not need to balance between CPUs:
3003 */
70b97a7f 3004static inline void idle_balance(int cpu, struct rq *rq)
1da177e4
LT
3005{
3006}
3007#endif
3008
1da177e4
LT
3009DEFINE_PER_CPU(struct kernel_stat, kstat);
3010
3011EXPORT_PER_CPU_SYMBOL(kstat);
3012
3013/*
3014 * This is called on clock ticks and on context switches.
3015 * Bank in p->sched_time the ns elapsed since the last tick or switch.
3016 */
48f24c4d 3017static inline void
70b97a7f 3018update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now)
1da177e4 3019{
b18ec803
MG
3020 p->sched_time += now - p->last_ran;
3021 p->last_ran = rq->most_recent_timestamp = now;
1da177e4
LT
3022}
3023
3024/*
3025 * Return current->sched_time plus any more ns on the sched_clock
3026 * that have not yet been banked.
3027 */
36c8b586 3028unsigned long long current_sched_time(const struct task_struct *p)
1da177e4
LT
3029{
3030 unsigned long long ns;
3031 unsigned long flags;
48f24c4d 3032
1da177e4 3033 local_irq_save(flags);
b18ec803 3034 ns = p->sched_time + sched_clock() - p->last_ran;
1da177e4 3035 local_irq_restore(flags);
48f24c4d 3036
1da177e4
LT
3037 return ns;
3038}
3039
f1adad78
LT
3040/*
3041 * We place interactive tasks back into the active array, if possible.
3042 *
3043 * To guarantee that this does not starve expired tasks we ignore the
3044 * interactivity of a task if the first expired task had to wait more
3045 * than a 'reasonable' amount of time. This deadline timeout is
3046 * load-dependent, as the frequency of array switched decreases with
3047 * increasing number of running tasks. We also ignore the interactivity
3048 * if a better static_prio task has expired:
3049 */
70b97a7f 3050static inline int expired_starving(struct rq *rq)
48f24c4d
IM
3051{
3052 if (rq->curr->static_prio > rq->best_expired_prio)
3053 return 1;
3054 if (!STARVATION_LIMIT || !rq->expired_timestamp)
3055 return 0;
3056 if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)
3057 return 1;
3058 return 0;
3059}
f1adad78 3060
1da177e4
LT
3061/*
3062 * Account user cpu time to a process.
3063 * @p: the process that the cpu time gets accounted to
3064 * @hardirq_offset: the offset to subtract from hardirq_count()
3065 * @cputime: the cpu time spent in user space since the last update
3066 */
3067void account_user_time(struct task_struct *p, cputime_t cputime)
3068{
3069 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3070 cputime64_t tmp;
3071
3072 p->utime = cputime_add(p->utime, cputime);
3073
3074 /* Add user time to cpustat. */
3075 tmp = cputime_to_cputime64(cputime);
3076 if (TASK_NICE(p) > 0)
3077 cpustat->nice = cputime64_add(cpustat->nice, tmp);
3078 else
3079 cpustat->user = cputime64_add(cpustat->user, tmp);
3080}
3081
3082/*
3083 * Account system cpu time to a process.
3084 * @p: the process that the cpu time gets accounted to
3085 * @hardirq_offset: the offset to subtract from hardirq_count()
3086 * @cputime: the cpu time spent in kernel space since the last update
3087 */
3088void account_system_time(struct task_struct *p, int hardirq_offset,
3089 cputime_t cputime)
3090{
3091 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
70b97a7f 3092 struct rq *rq = this_rq();
1da177e4
LT
3093 cputime64_t tmp;
3094
3095 p->stime = cputime_add(p->stime, cputime);
3096
3097 /* Add system time to cpustat. */
3098 tmp = cputime_to_cputime64(cputime);
3099 if (hardirq_count() - hardirq_offset)
3100 cpustat->irq = cputime64_add(cpustat->irq, tmp);
3101 else if (softirq_count())
3102 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3103 else if (p != rq->idle)
3104 cpustat->system = cputime64_add(cpustat->system, tmp);
3105 else if (atomic_read(&rq->nr_iowait) > 0)
3106 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3107 else
3108 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3109 /* Account for system time used */
3110 acct_update_integrals(p);
1da177e4
LT
3111}
3112
3113/*
3114 * Account for involuntary wait time.
3115 * @p: the process from which the cpu time has been stolen
3116 * @steal: the cpu time spent in involuntary wait
3117 */
3118void account_steal_time(struct task_struct *p, cputime_t steal)
3119{
3120 struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3121 cputime64_t tmp = cputime_to_cputime64(steal);
70b97a7f 3122 struct rq *rq = this_rq();
1da177e4
LT
3123
3124 if (p == rq->idle) {
3125 p->stime = cputime_add(p->stime, steal);
3126 if (atomic_read(&rq->nr_iowait) > 0)
3127 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
3128 else
3129 cpustat->idle = cputime64_add(cpustat->idle, tmp);
3130 } else
3131 cpustat->steal = cputime64_add(cpustat->steal, tmp);
3132}
3133
7835b98b 3134static void task_running_tick(struct rq *rq, struct task_struct *p)
1da177e4 3135{
1da177e4 3136 if (p->array != rq->active) {
7835b98b 3137 /* Task has expired but was not scheduled yet */
1da177e4 3138 set_tsk_need_resched(p);
7835b98b 3139 return;
1da177e4
LT
3140 }
3141 spin_lock(&rq->lock);
3142 /*
3143 * The task was running during this tick - update the
3144 * time slice counter. Note: we do not update a thread's
3145 * priority until it either goes to sleep or uses up its
3146 * timeslice. This makes it possible for interactive tasks
3147 * to use up their timeslices at their highest priority levels.
3148 */
3149 if (rt_task(p)) {
3150 /*
3151 * RR tasks need a special form of timeslice management.
3152 * FIFO tasks have no timeslices.
3153 */
3154 if ((p->policy == SCHED_RR) && !--p->time_slice) {
3155 p->time_slice = task_timeslice(p);
3156 p->first_time_slice = 0;
3157 set_tsk_need_resched(p);
3158
3159 /* put it at the end of the queue: */
3160 requeue_task(p, rq->active);
3161 }
3162 goto out_unlock;
3163 }
3164 if (!--p->time_slice) {
3165 dequeue_task(p, rq->active);
3166 set_tsk_need_resched(p);
3167 p->prio = effective_prio(p);
3168 p->time_slice = task_timeslice(p);
3169 p->first_time_slice = 0;
3170
3171 if (!rq->expired_timestamp)
3172 rq->expired_timestamp = jiffies;
48f24c4d 3173 if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {
1da177e4
LT
3174 enqueue_task(p, rq->expired);
3175 if (p->static_prio < rq->best_expired_prio)
3176 rq->best_expired_prio = p->static_prio;
3177 } else
3178 enqueue_task(p, rq->active);
3179 } else {
3180 /*
3181 * Prevent a too long timeslice allowing a task to monopolize
3182 * the CPU. We do this by splitting up the timeslice into
3183 * smaller pieces.
3184 *
3185 * Note: this does not mean the task's timeslices expire or
3186 * get lost in any way, they just might be preempted by
3187 * another task of equal priority. (one with higher
3188 * priority would have preempted this task already.) We
3189 * requeue this task to the end of the list on this priority
3190 * level, which is in essence a round-robin of tasks with
3191 * equal priority.
3192 *
3193 * This only applies to tasks in the interactive
3194 * delta range with at least TIMESLICE_GRANULARITY to requeue.
3195 */
3196 if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
3197 p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
3198 (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
3199 (p->array == rq->active)) {
3200
3201 requeue_task(p, rq->active);
3202 set_tsk_need_resched(p);
3203 }
3204 }
3205out_unlock:
3206 spin_unlock(&rq->lock);
7835b98b
CL
3207}
3208
3209/*
3210 * This function gets called by the timer code, with HZ frequency.
3211 * We call it with interrupts disabled.
3212 *
3213 * It also gets called by the fork code, when changing the parent's
3214 * timeslices.
3215 */
3216void scheduler_tick(void)
3217{
3218 unsigned long long now = sched_clock();
3219 struct task_struct *p = current;
3220 int cpu = smp_processor_id();
3221 struct rq *rq = cpu_rq(cpu);
7835b98b
CL
3222
3223 update_cpu_clock(p, rq, now);
3224
69f7c0a1 3225 if (p != rq->idle)
7835b98b 3226 task_running_tick(rq, p);
e418e1c2 3227#ifdef CONFIG_SMP
7835b98b 3228 update_load(rq);
c9819f45
CL
3229 if (time_after_eq(jiffies, rq->next_balance))
3230 raise_softirq(SCHED_SOFTIRQ);
e418e1c2 3231#endif
1da177e4
LT
3232}
3233
1da177e4
LT
3234#if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3235
3236void fastcall add_preempt_count(int val)
3237{
3238 /*
3239 * Underflow?
3240 */
9a11b49a
IM
3241 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3242 return;
1da177e4
LT
3243 preempt_count() += val;
3244 /*
3245 * Spinlock count overflowing soon?
3246 */
33859f7f
MOS
3247 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3248 PREEMPT_MASK - 10);
1da177e4
LT
3249}
3250EXPORT_SYMBOL(add_preempt_count);
3251
3252void fastcall sub_preempt_count(int val)
3253{
3254 /*
3255 * Underflow?
3256 */
9a11b49a
IM
3257 if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3258 return;
1da177e4
LT
3259 /*
3260 * Is the spinlock portion underflowing?
3261 */
9a11b49a
IM
3262 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3263 !(preempt_count() & PREEMPT_MASK)))
3264 return;
3265
1da177e4
LT
3266 preempt_count() -= val;
3267}
3268EXPORT_SYMBOL(sub_preempt_count);
3269
3270#endif
3271
3dee386e
CK
3272static inline int interactive_sleep(enum sleep_type sleep_type)
3273{
3274 return (sleep_type == SLEEP_INTERACTIVE ||
3275 sleep_type == SLEEP_INTERRUPTED);
3276}
3277
1da177e4
LT
3278/*
3279 * schedule() is the main scheduler function.
3280 */
3281asmlinkage void __sched schedule(void)
3282{
36c8b586 3283 struct task_struct *prev, *next;
70b97a7f 3284 struct prio_array *array;
1da177e4
LT
3285 struct list_head *queue;
3286 unsigned long long now;
3287 unsigned long run_time;
a3464a10 3288 int cpu, idx, new_prio;
48f24c4d 3289 long *switch_count;
70b97a7f 3290 struct rq *rq;
1da177e4
LT
3291
3292 /*
3293 * Test if we are atomic. Since do_exit() needs to call into
3294 * schedule() atomically, we ignore that path for now.
3295 * Otherwise, whine if we are scheduling when we should not be.
3296 */
77e4bfbc
AM
3297 if (unlikely(in_atomic() && !current->exit_state)) {
3298 printk(KERN_ERR "BUG: scheduling while atomic: "
3299 "%s/0x%08x/%d\n",
3300 current->comm, preempt_count(), current->pid);
a4c410f0 3301 debug_show_held_locks(current);
3117df04
IM
3302 if (irqs_disabled())
3303 print_irqtrace_events(current);
77e4bfbc 3304 dump_stack();
1da177e4
LT
3305 }
3306 profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3307
3308need_resched:
3309 preempt_disable();
3310 prev = current;
3311 release_kernel_lock(prev);
3312need_resched_nonpreemptible:
3313 rq = this_rq();
3314
3315 /*
3316 * The idle thread is not allowed to schedule!
3317 * Remove this check after it has been exercised a bit.
3318 */
3319 if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
3320 printk(KERN_ERR "bad: scheduling from the idle thread!\n");
3321 dump_stack();
3322 }
3323
3324 schedstat_inc(rq, sched_cnt);
3325 now = sched_clock();
238628ed 3326 if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
1da177e4 3327 run_time = now - prev->timestamp;
238628ed 3328 if (unlikely((long long)(now - prev->timestamp) < 0))
1da177e4
LT
3329 run_time = 0;
3330 } else
3331 run_time = NS_MAX_SLEEP_AVG;
3332
3333 /*
3334 * Tasks charged proportionately less run_time at high sleep_avg to
3335 * delay them losing their interactive status
3336 */
3337 run_time /= (CURRENT_BONUS(prev) ? : 1);
3338
3339 spin_lock_irq(&rq->lock);
3340
1da177e4
LT
3341 switch_count = &prev->nivcsw;
3342 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3343 switch_count = &prev->nvcsw;
3344 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
3345 unlikely(signal_pending(prev))))
3346 prev->state = TASK_RUNNING;
3347 else {
3348 if (prev->state == TASK_UNINTERRUPTIBLE)
3349 rq->nr_uninterruptible++;
3350 deactivate_task(prev, rq);
3351 }
3352 }
3353
3354 cpu = smp_processor_id();
3355 if (unlikely(!rq->nr_running)) {
1da177e4
LT
3356 idle_balance(cpu, rq);
3357 if (!rq->nr_running) {
3358 next = rq->idle;
3359 rq->expired_timestamp = 0;
1da177e4
LT
3360 goto switch_tasks;
3361 }
1da177e4
LT
3362 }
3363
3364 array = rq->active;
3365 if (unlikely(!array->nr_active)) {
3366 /*
3367 * Switch the active and expired arrays.
3368 */
3369 schedstat_inc(rq, sched_switch);
3370 rq->active = rq->expired;
3371 rq->expired = array;
3372 array = rq->active;
3373 rq->expired_timestamp = 0;
3374 rq->best_expired_prio = MAX_PRIO;
3375 }
3376
3377 idx = sched_find_first_bit(array->bitmap);
3378 queue = array->queue + idx;
36c8b586 3379 next = list_entry(queue->next, struct task_struct, run_list);
1da177e4 3380
3dee386e 3381 if (!rt_task(next) && interactive_sleep(next->sleep_type)) {
1da177e4 3382 unsigned long long delta = now - next->timestamp;
238628ed 3383 if (unlikely((long long)(now - next->timestamp) < 0))
1da177e4
LT
3384 delta = 0;
3385
3dee386e 3386 if (next->sleep_type == SLEEP_INTERACTIVE)
1da177e4
LT
3387 delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
3388
3389 array = next->array;
a3464a10
CS
3390 new_prio = recalc_task_prio(next, next->timestamp + delta);
3391
3392 if (unlikely(next->prio != new_prio)) {
3393 dequeue_task(next, array);
3394 next->prio = new_prio;
3395 enqueue_task(next, array);
7c4bb1f9 3396 }
1da177e4 3397 }
3dee386e 3398 next->sleep_type = SLEEP_NORMAL;
1da177e4
LT
3399switch_tasks:
3400 if (next == rq->idle)
3401 schedstat_inc(rq, sched_goidle);
3402 prefetch(next);
383f2835 3403 prefetch_stack(next);
1da177e4
LT
3404 clear_tsk_need_resched(prev);
3405 rcu_qsctr_inc(task_cpu(prev));
3406
3407 update_cpu_clock(prev, rq, now);
3408
3409 prev->sleep_avg -= run_time;
3410 if ((long)prev->sleep_avg <= 0)
3411 prev->sleep_avg = 0;
3412 prev->timestamp = prev->last_ran = now;
3413
3414 sched_info_switch(prev, next);
3415 if (likely(prev != next)) {
c1e16aa2 3416 next->timestamp = next->last_ran = now;
1da177e4
LT
3417 rq->nr_switches++;
3418 rq->curr = next;
3419 ++*switch_count;
3420
4866cde0 3421 prepare_task_switch(rq, next);
1da177e4
LT
3422 prev = context_switch(rq, prev, next);
3423 barrier();
4866cde0
NP
3424 /*
3425 * this_rq must be evaluated again because prev may have moved
3426 * CPUs since it called schedule(), thus the 'rq' on its stack
3427 * frame will be invalid.
3428 */
3429 finish_task_switch(this_rq(), prev);
1da177e4
LT
3430 } else
3431 spin_unlock_irq(&rq->lock);
3432
3433 prev = current;
3434 if (unlikely(reacquire_kernel_lock(prev) < 0))
3435 goto need_resched_nonpreemptible;
3436 preempt_enable_no_resched();
3437 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3438 goto need_resched;
3439}
1da177e4
LT
3440EXPORT_SYMBOL(schedule);
3441
3442#ifdef CONFIG_PREEMPT
3443/*
2ed6e34f 3444 * this is the entry point to schedule() from in-kernel preemption
1da177e4
LT
3445 * off of preempt_enable. Kernel preemptions off return from interrupt
3446 * occur there and call schedule directly.
3447 */
3448asmlinkage void __sched preempt_schedule(void)
3449{
3450 struct thread_info *ti = current_thread_info();
3451#ifdef CONFIG_PREEMPT_BKL
3452 struct task_struct *task = current;
3453 int saved_lock_depth;
3454#endif
3455 /*
3456 * If there is a non-zero preempt_count or interrupts are disabled,
3457 * we do not want to preempt the current task. Just return..
3458 */
beed33a8 3459 if (likely(ti->preempt_count || irqs_disabled()))
1da177e4
LT
3460 return;
3461
3462need_resched:
3463 add_preempt_count(PREEMPT_ACTIVE);
3464 /*
3465 * We keep the big kernel semaphore locked, but we
3466 * clear ->lock_depth so that schedule() doesnt
3467 * auto-release the semaphore:
3468 */
3469#ifdef CONFIG_PREEMPT_BKL
3470 saved_lock_depth = task->lock_depth;
3471 task->lock_depth = -1;
3472#endif
3473 schedule();
3474#ifdef CONFIG_PREEMPT_BKL
3475 task->lock_depth = saved_lock_depth;
3476#endif
3477 sub_preempt_count(PREEMPT_ACTIVE);
3478
3479 /* we could miss a preemption opportunity between schedule and now */
3480 barrier();
3481 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3482 goto need_resched;
3483}
1da177e4
LT
3484EXPORT_SYMBOL(preempt_schedule);
3485
3486/*
2ed6e34f 3487 * this is the entry point to schedule() from kernel preemption
1da177e4
LT
3488 * off of irq context.
3489 * Note, that this is called and return with irqs disabled. This will
3490 * protect us against recursive calling from irq.
3491 */
3492asmlinkage void __sched preempt_schedule_irq(void)
3493{
3494 struct thread_info *ti = current_thread_info();
3495#ifdef CONFIG_PREEMPT_BKL
3496 struct task_struct *task = current;
3497 int saved_lock_depth;
3498#endif
2ed6e34f 3499 /* Catch callers which need to be fixed */
1da177e4
LT
3500 BUG_ON(ti->preempt_count || !irqs_disabled());
3501
3502need_resched:
3503 add_preempt_count(PREEMPT_ACTIVE);
3504 /*
3505 * We keep the big kernel semaphore locked, but we
3506 * clear ->lock_depth so that schedule() doesnt
3507 * auto-release the semaphore:
3508 */
3509#ifdef CONFIG_PREEMPT_BKL
3510 saved_lock_depth = task->lock_depth;
3511 task->lock_depth = -1;
3512#endif
3513 local_irq_enable();
3514 schedule();
3515 local_irq_disable();
3516#ifdef CONFIG_PREEMPT_BKL
3517 task->lock_depth = saved_lock_depth;
3518#endif
3519 sub_preempt_count(PREEMPT_ACTIVE);
3520
3521 /* we could miss a preemption opportunity between schedule and now */
3522 barrier();
3523 if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3524 goto need_resched;
3525}
3526
3527#endif /* CONFIG_PREEMPT */
3528
95cdf3b7
IM
3529int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
3530 void *key)
1da177e4 3531{
48f24c4d 3532 return try_to_wake_up(curr->private, mode, sync);
1da177e4 3533}
1da177e4
LT
3534EXPORT_SYMBOL(default_wake_function);
3535
3536/*
3537 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3538 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3539 * number) then we wake all the non-exclusive tasks and one exclusive task.
3540 *
3541 * There are circumstances in which we can try to wake a task which has already
3542 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3543 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3544 */
3545static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3546 int nr_exclusive, int sync, void *key)
3547{
3548 struct list_head *tmp, *next;
3549
3550 list_for_each_safe(tmp, next, &q->task_list) {
48f24c4d
IM
3551 wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list);
3552 unsigned flags = curr->flags;
3553
1da177e4 3554 if (curr->func(curr, mode, sync, key) &&
48f24c4d 3555 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
1da177e4
LT
3556 break;
3557 }
3558}
3559
3560/**
3561 * __wake_up - wake up threads blocked on a waitqueue.
3562 * @q: the waitqueue
3563 * @mode: which threads
3564 * @nr_exclusive: how many wake-one or wake-many threads to wake up
67be2dd1 3565 * @key: is directly passed to the wakeup function
1da177e4
LT
3566 */
3567void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
95cdf3b7 3568 int nr_exclusive, void *key)
1da177e4
LT
3569{
3570 unsigned long flags;
3571
3572 spin_lock_irqsave(&q->lock, flags);
3573 __wake_up_common(q, mode, nr_exclusive, 0, key);
3574 spin_unlock_irqrestore(&q->lock, flags);
3575}
1da177e4
LT
3576EXPORT_SYMBOL(__wake_up);
3577
3578/*
3579 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3580 */
3581void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3582{
3583 __wake_up_common(q, mode, 1, 0, NULL);
3584}
3585
3586/**
67be2dd1 3587 * __wake_up_sync - wake up threads blocked on a waitqueue.
1da177e4
LT
3588 * @q: the waitqueue
3589 * @mode: which threads
3590 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3591 *
3592 * The sync wakeup differs that the waker knows that it will schedule
3593 * away soon, so while the target thread will be woken up, it will not
3594 * be migrated to another CPU - ie. the two threads are 'synchronized'
3595 * with each other. This can prevent needless bouncing between CPUs.
3596 *
3597 * On UP it can prevent extra preemption.
3598 */
95cdf3b7
IM
3599void fastcall
3600__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
1da177e4
LT
3601{
3602 unsigned long flags;
3603 int sync = 1;
3604
3605 if (unlikely(!q))
3606 return;
3607
3608 if (unlikely(!nr_exclusive))
3609 sync = 0;
3610
3611 spin_lock_irqsave(&q->lock, flags);
3612 __wake_up_common(q, mode, nr_exclusive, sync, NULL);
3613 spin_unlock_irqrestore(&q->lock, flags);
3614}
3615EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
3616
3617void fastcall complete(struct completion *x)
3618{
3619 unsigned long flags;
3620
3621 spin_lock_irqsave(&x->wait.lock, flags);
3622 x->done++;
3623 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3624 1, 0, NULL);
3625 spin_unlock_irqrestore(&x->wait.lock, flags);
3626}
3627EXPORT_SYMBOL(complete);
3628
3629void fastcall complete_all(struct completion *x)
3630{
3631 unsigned long flags;
3632
3633 spin_lock_irqsave(&x->wait.lock, flags);
3634 x->done += UINT_MAX/2;
3635 __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3636 0, 0, NULL);
3637 spin_unlock_irqrestore(&x->wait.lock, flags);
3638}
3639EXPORT_SYMBOL(complete_all);
3640
3641void fastcall __sched wait_for_completion(struct completion *x)
3642{
3643 might_sleep();
48f24c4d 3644
1da177e4
LT
3645 spin_lock_irq(&x->wait.lock);
3646 if (!x->done) {
3647 DECLARE_WAITQUEUE(wait, current);
3648
3649 wait.flags |= WQ_FLAG_EXCLUSIVE;
3650 __add_wait_queue_tail(&x->wait, &wait);
3651 do {
3652 __set_current_state(TASK_UNINTERRUPTIBLE);
3653 spin_unlock_irq(&x->wait.lock);
3654 schedule();
3655 spin_lock_irq(&x->wait.lock);
3656 } while (!x->done);
3657 __remove_wait_queue(&x->wait, &wait);
3658 }
3659 x->done--;
3660 spin_unlock_irq(&x->wait.lock);
3661}
3662EXPORT_SYMBOL(wait_for_completion);
3663
3664unsigned long fastcall __sched
3665wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3666{
3667 might_sleep();
3668
3669 spin_lock_irq(&x->wait.lock);
3670 if (!x->done) {
3671 DECLARE_WAITQUEUE(wait, current);
3672
3673 wait.flags |= WQ_FLAG_EXCLUSIVE;
3674 __add_wait_queue_tail(&x->wait, &wait);
3675 do {
3676 __set_current_state(TASK_UNINTERRUPTIBLE);
3677 spin_unlock_irq(&x->wait.lock);
3678 timeout = schedule_timeout(timeout);
3679 spin_lock_irq(&x->wait.lock);
3680 if (!timeout) {
3681 __remove_wait_queue(&x->wait, &wait);
3682 goto out;
3683 }
3684 } while (!x->done);
3685 __remove_wait_queue(&x->wait, &wait);
3686 }
3687 x->done--;
3688out:
3689 spin_unlock_irq(&x->wait.lock);
3690 return timeout;
3691}
3692EXPORT_SYMBOL(wait_for_completion_timeout);
3693
3694int fastcall __sched wait_for_completion_interruptible(struct completion *x)
3695{
3696 int ret = 0;
3697
3698 might_sleep();
3699
3700 spin_lock_irq(&x->wait.lock);
3701 if (!x->done) {
3702 DECLARE_WAITQUEUE(wait, current);
3703
3704 wait.flags |= WQ_FLAG_EXCLUSIVE;
3705 __add_wait_queue_tail(&x->wait, &wait);
3706 do {
3707 if (signal_pending(current)) {
3708 ret = -ERESTARTSYS;
3709 __remove_wait_queue(&x->wait, &wait);
3710 goto out;
3711 }
3712 __set_current_state(TASK_INTERRUPTIBLE);
3713 spin_unlock_irq(&x->wait.lock);
3714 schedule();
3715 spin_lock_irq(&x->wait.lock);
3716 } while (!x->done);
3717 __remove_wait_queue(&x->wait, &wait);
3718 }
3719 x->done--;
3720out:
3721 spin_unlock_irq(&x->wait.lock);
3722
3723 return ret;
3724}
3725EXPORT_SYMBOL(wait_for_completion_interruptible);
3726
3727unsigned long fastcall __sched
3728wait_for_completion_interruptible_timeout(struct completion *x,
3729 unsigned long timeout)
3730{
3731 might_sleep();
3732
3733 spin_lock_irq(&x->wait.lock);
3734 if (!x->done) {
3735 DECLARE_WAITQUEUE(wait, current);
3736
3737 wait.flags |= WQ_FLAG_EXCLUSIVE;
3738 __add_wait_queue_tail(&x->wait, &wait);
3739 do {
3740 if (signal_pending(current)) {
3741 timeout = -ERESTARTSYS;
3742 __remove_wait_queue(&x->wait, &wait);
3743 goto out;
3744 }
3745 __set_current_state(TASK_INTERRUPTIBLE);
3746 spin_unlock_irq(&x->wait.lock);
3747 timeout = schedule_timeout(timeout);
3748 spin_lock_irq(&x->wait.lock);
3749 if (!timeout) {
3750 __remove_wait_queue(&x->wait, &wait);
3751 goto out;
3752 }
3753 } while (!x->done);
3754 __remove_wait_queue(&x->wait, &wait);
3755 }
3756 x->done--;
3757out:
3758 spin_unlock_irq(&x->wait.lock);
3759 return timeout;
3760}
3761EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3762
3763
3764#define SLEEP_ON_VAR \
3765 unsigned long flags; \
3766 wait_queue_t wait; \
3767 init_waitqueue_entry(&wait, current);
3768
3769#define SLEEP_ON_HEAD \
3770 spin_lock_irqsave(&q->lock,flags); \
3771 __add_wait_queue(q, &wait); \
3772 spin_unlock(&q->lock);
3773
3774#define SLEEP_ON_TAIL \
3775 spin_lock_irq(&q->lock); \
3776 __remove_wait_queue(q, &wait); \
3777 spin_unlock_irqrestore(&q->lock, flags);
3778
3779void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
3780{
3781 SLEEP_ON_VAR
3782
3783 current->state = TASK_INTERRUPTIBLE;
3784
3785 SLEEP_ON_HEAD
3786 schedule();
3787 SLEEP_ON_TAIL
3788}
1da177e4
LT
3789EXPORT_SYMBOL(interruptible_sleep_on);
3790
95cdf3b7
IM
3791long fastcall __sched
3792interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
1da177e4
LT
3793{
3794 SLEEP_ON_VAR
3795
3796 current->state = TASK_INTERRUPTIBLE;
3797
3798 SLEEP_ON_HEAD
3799 timeout = schedule_timeout(timeout);
3800 SLEEP_ON_TAIL
3801
3802 return timeout;
3803}
1da177e4
LT
3804EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3805
3806void fastcall __sched sleep_on(wait_queue_head_t *q)
3807{
3808 SLEEP_ON_VAR
3809
3810 current->state = TASK_UNINTERRUPTIBLE;
3811
3812 SLEEP_ON_HEAD
3813 schedule();
3814 SLEEP_ON_TAIL
3815}
1da177e4
LT
3816EXPORT_SYMBOL(sleep_on);
3817
3818long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3819{
3820 SLEEP_ON_VAR
3821
3822 current->state = TASK_UNINTERRUPTIBLE;
3823
3824 SLEEP_ON_HEAD
3825 timeout = schedule_timeout(timeout);
3826 SLEEP_ON_TAIL
3827
3828 return timeout;
3829}
3830
3831EXPORT_SYMBOL(sleep_on_timeout);
3832
b29739f9
IM
3833#ifdef CONFIG_RT_MUTEXES
3834
3835/*
3836 * rt_mutex_setprio - set the current priority of a task
3837 * @p: task
3838 * @prio: prio value (kernel-internal form)
3839 *
3840 * This function changes the 'effective' priority of a task. It does
3841 * not touch ->normal_prio like __setscheduler().
3842 *
3843 * Used by the rt_mutex code to implement priority inheritance logic.
3844 */
36c8b586 3845void rt_mutex_setprio(struct task_struct *p, int prio)
b29739f9 3846{
70b97a7f 3847 struct prio_array *array;
b29739f9 3848 unsigned long flags;
70b97a7f 3849 struct rq *rq;
b29739f9
IM
3850 int oldprio;
3851
3852 BUG_ON(prio < 0 || prio > MAX_PRIO);
3853
3854 rq = task_rq_lock(p, &flags);
3855
3856 oldprio = p->prio;
3857 array = p->array;
3858 if (array)
3859 dequeue_task(p, array);
3860 p->prio = prio;
3861
3862 if (array) {
3863 /*
3864 * If changing to an RT priority then queue it
3865 * in the active array!
3866 */
3867 if (rt_task(p))
3868 array = rq->active;
3869 enqueue_task(p, array);
3870 /*
3871 * Reschedule if we are currently running on this runqueue and
3872 * our priority decreased, or if we are not currently running on
3873 * this runqueue and our priority is higher than the current's
3874 */
3875 if (task_running(rq, p)) {
3876 if (p->prio > oldprio)
3877 resched_task(rq->curr);
3878 } else if (TASK_PREEMPTS_CURR(p, rq))
3879 resched_task(rq->curr);
3880 }
3881 task_rq_unlock(rq, &flags);
3882}
3883
3884#endif
3885
36c8b586 3886void set_user_nice(struct task_struct *p, long nice)
1da177e4 3887{
70b97a7f 3888 struct prio_array *array;
48f24c4d 3889 int old_prio, delta;
1da177e4 3890 unsigned long flags;
70b97a7f 3891 struct rq *rq;
1da177e4
LT
3892
3893 if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3894 return;
3895 /*
3896 * We have to be careful, if called from sys_setpriority(),
3897 * the task might be in the middle of scheduling on another CPU.
3898 */
3899 rq = task_rq_lock(p, &flags);
3900 /*
3901 * The RT priorities are set via sched_setscheduler(), but we still
3902 * allow the 'normal' nice value to be set - but as expected
3903 * it wont have any effect on scheduling until the task is
b0a9499c 3904 * not SCHED_NORMAL/SCHED_BATCH:
1da177e4 3905 */
b29739f9 3906 if (has_rt_policy(p)) {
1da177e4
LT
3907 p->static_prio = NICE_TO_PRIO(nice);
3908 goto out_unlock;
3909 }
3910 array = p->array;
2dd73a4f 3911 if (array) {
1da177e4 3912 dequeue_task(p, array);
2dd73a4f
PW
3913 dec_raw_weighted_load(rq, p);
3914 }
1da177e4 3915
1da177e4 3916 p->static_prio = NICE_TO_PRIO(nice);
2dd73a4f 3917 set_load_weight(p);
b29739f9
IM
3918 old_prio = p->prio;
3919 p->prio = effective_prio(p);
3920 delta = p->prio - old_prio;
1da177e4
LT
3921
3922 if (array) {
3923 enqueue_task(p, array);
2dd73a4f 3924 inc_raw_weighted_load(rq, p);
1da177e4
LT
3925 /*
3926 * If the task increased its priority or is running and
3927 * lowered its priority, then reschedule its CPU:
3928 */
3929 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3930 resched_task(rq->curr);
3931 }
3932out_unlock:
3933 task_rq_unlock(rq, &flags);
3934}
1da177e4
LT
3935EXPORT_SYMBOL(set_user_nice);
3936
e43379f1
MM
3937/*
3938 * can_nice - check if a task can reduce its nice value
3939 * @p: task
3940 * @nice: nice value
3941 */
36c8b586 3942int can_nice(const struct task_struct *p, const int nice)
e43379f1 3943{
024f4747
MM
3944 /* convert nice value [19,-20] to rlimit style value [1,40] */
3945 int nice_rlim = 20 - nice;
48f24c4d 3946
e43379f1
MM
3947 return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
3948 capable(CAP_SYS_NICE));
3949}
3950
1da177e4
LT
3951#ifdef __ARCH_WANT_SYS_NICE
3952
3953/*
3954 * sys_nice - change the priority of the current process.
3955 * @increment: priority increment
3956 *
3957 * sys_setpriority is a more generic, but much slower function that
3958 * does similar things.
3959 */
3960asmlinkage long sys_nice(int increment)
3961{
48f24c4d 3962 long nice, retval;
1da177e4
LT
3963
3964 /*
3965 * Setpriority might change our priority at the same moment.
3966 * We don't have to worry. Conceptually one call occurs first
3967 * and we have a single winner.
3968 */
e43379f1
MM
3969 if (increment < -40)
3970 increment = -40;
1da177e4
LT
3971 if (increment > 40)
3972 increment = 40;
3973
3974 nice = PRIO_TO_NICE(current->static_prio) + increment;
3975 if (nice < -20)
3976 nice = -20;
3977 if (nice > 19)
3978 nice = 19;
3979
e43379f1
MM
3980 if (increment < 0 && !can_nice(current, nice))
3981 return -EPERM;
3982
1da177e4
LT
3983 retval = security_task_setnice(current, nice);
3984 if (retval)
3985 return retval;
3986
3987 set_user_nice(current, nice);
3988 return 0;
3989}
3990
3991#endif
3992
3993/**
3994 * task_prio - return the priority value of a given task.
3995 * @p: the task in question.
3996 *
3997 * This is the priority value as seen by users in /proc.
3998 * RT tasks are offset by -200. Normal tasks are centered
3999 * around 0, value goes from -16 to +15.
4000 */
36c8b586 4001int task_prio(const struct task_struct *p)
1da177e4
LT
4002{
4003 return p->prio - MAX_RT_PRIO;
4004}
4005
4006/**
4007 * task_nice - return the nice value of a given task.
4008 * @p: the task in question.
4009 */
36c8b586 4010int task_nice(const struct task_struct *p)
1da177e4
LT
4011{
4012 return TASK_NICE(p);
4013}
1da177e4 4014EXPORT_SYMBOL_GPL(task_nice);
1da177e4
LT
4015
4016/**
4017 * idle_cpu - is a given cpu idle currently?
4018 * @cpu: the processor in question.
4019 */
4020int idle_cpu(int cpu)
4021{
4022 return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4023}
4024
1da177e4
LT
4025/**
4026 * idle_task - return the idle task for a given cpu.
4027 * @cpu: the processor in question.
4028 */
36c8b586 4029struct task_struct *idle_task(int cpu)
1da177e4
LT
4030{
4031 return cpu_rq(cpu)->idle;
4032}
4033
4034/**
4035 * find_process_by_pid - find a process with a matching PID value.
4036 * @pid: the pid in question.
4037 */
36c8b586 4038static inline struct task_struct *find_process_by_pid(pid_t pid)
1da177e4
LT
4039{
4040 return pid ? find_task_by_pid(pid) : current;
4041}
4042
4043/* Actually do priority change: must hold rq lock. */
4044static void __setscheduler(struct task_struct *p, int policy, int prio)
4045{
4046 BUG_ON(p->array);
48f24c4d 4047
1da177e4
LT
4048 p->policy = policy;
4049 p->rt_priority = prio;
b29739f9
IM
4050 p->normal_prio = normal_prio(p);
4051 /* we are holding p->pi_lock already */
4052 p->prio = rt_mutex_getprio(p);
4053 /*
4054 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
4055 */
4056 if (policy == SCHED_BATCH)
4057 p->sleep_avg = 0;
2dd73a4f 4058 set_load_weight(p);
1da177e4
LT
4059}
4060
4061/**
72fd4a35 4062 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
1da177e4
LT
4063 * @p: the task in question.
4064 * @policy: new policy.
4065 * @param: structure containing the new RT priority.
5fe1d75f 4066 *
72fd4a35 4067 * NOTE that the task may be already dead.
1da177e4 4068 */
95cdf3b7
IM
4069int sched_setscheduler(struct task_struct *p, int policy,
4070 struct sched_param *param)
1da177e4 4071{
48f24c4d 4072 int retval, oldprio, oldpolicy = -1;
70b97a7f 4073 struct prio_array *array;
1da177e4 4074 unsigned long flags;
70b97a7f 4075 struct rq *rq;
1da177e4 4076
66e5393a
SR
4077 /* may grab non-irq protected spin_locks */
4078 BUG_ON(in_interrupt());
1da177e4
LT
4079recheck:
4080 /* double check policy once rq lock held */
4081 if (policy < 0)
4082 policy = oldpolicy = p->policy;
4083 else if (policy != SCHED_FIFO && policy != SCHED_RR &&
b0a9499c
IM
4084 policy != SCHED_NORMAL && policy != SCHED_BATCH)
4085 return -EINVAL;
1da177e4
LT
4086 /*
4087 * Valid priorities for SCHED_FIFO and SCHED_RR are
b0a9499c
IM
4088 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
4089 * SCHED_BATCH is 0.
1da177e4
LT
4090 */
4091 if (param->sched_priority < 0 ||
95cdf3b7 4092 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
d46523ea 4093 (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
1da177e4 4094 return -EINVAL;
57a6f51c 4095 if (is_rt_policy(policy) != (param->sched_priority != 0))
1da177e4
LT
4096 return -EINVAL;
4097
37e4ab3f
OC
4098 /*
4099 * Allow unprivileged RT tasks to decrease priority:
4100 */
4101 if (!capable(CAP_SYS_NICE)) {
8dc3e909
ON
4102 if (is_rt_policy(policy)) {
4103 unsigned long rlim_rtprio;
4104 unsigned long flags;
4105
4106 if (!lock_task_sighand(p, &flags))
4107 return -ESRCH;
4108 rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur;
4109 unlock_task_sighand(p, &flags);
4110
4111 /* can't set/change the rt policy */
4112 if (policy != p->policy && !rlim_rtprio)
4113 return -EPERM;
4114
4115 /* can't increase priority */
4116 if (param->sched_priority > p->rt_priority &&
4117 param->sched_priority > rlim_rtprio)
4118 return -EPERM;
4119 }
5fe1d75f 4120
37e4ab3f
OC
4121 /* can't change other user's priorities */
4122 if ((current->euid != p->euid) &&
4123 (current->euid != p->uid))
4124 return -EPERM;
4125 }
1da177e4
LT
4126
4127 retval = security_task_setscheduler(p, policy, param);
4128 if (retval)
4129 return retval;
b29739f9
IM
4130 /*
4131 * make sure no PI-waiters arrive (or leave) while we are
4132 * changing the priority of the task:
4133 */
4134 spin_lock_irqsave(&p->pi_lock, flags);
1da177e4
LT
4135 /*
4136 * To be able to change p->policy safely, the apropriate
4137 * runqueue lock must be held.
4138 */
b29739f9 4139 rq = __task_rq_lock(p);
1da177e4
LT
4140 /* recheck policy now with rq lock held */
4141 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4142 policy = oldpolicy = -1;
b29739f9
IM
4143 __task_rq_unlock(rq);
4144 spin_unlock_irqrestore(&p->pi_lock, flags);
1da177e4
LT
4145 goto recheck;
4146 }
4147 array = p->array;
4148 if (array)
4149 deactivate_task(p, rq);
4150 oldprio = p->prio;
4151 __setscheduler(p, policy, param->sched_priority);
4152 if (array) {
4153 __activate_task(p, rq);
4154 /*
4155 * Reschedule if we are currently running on this runqueue and
4156 * our priority decreased, or if we are not currently running on
4157 * this runqueue and our priority is higher than the current's
4158 */
4159 if (task_running(rq, p)) {
4160 if (p->prio > oldprio)
4161 resched_task(rq->curr);
4162 } else if (TASK_PREEMPTS_CURR(p, rq))
4163 resched_task(rq->curr);
4164 }
b29739f9
IM
4165 __task_rq_unlock(rq);
4166 spin_unlock_irqrestore(&p->pi_lock, flags);
4167
95e02ca9
TG
4168 rt_mutex_adjust_pi(p);
4169
1da177e4
LT
4170 return 0;
4171}
4172EXPORT_SYMBOL_GPL(sched_setscheduler);
4173
95cdf3b7
IM
4174static int
4175do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
1da177e4 4176{
1da177e4
LT
4177 struct sched_param lparam;
4178 struct task_struct *p;
36c8b586 4179 int retval;
1da177e4
LT
4180
4181 if (!param || pid < 0)
4182 return -EINVAL;
4183 if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4184 return -EFAULT;
5fe1d75f
ON
4185
4186 rcu_read_lock();
4187 retval = -ESRCH;
1da177e4 4188 p = find_process_by_pid(pid);
5fe1d75f
ON
4189 if (p != NULL)
4190 retval = sched_setscheduler(p, policy, &lparam);
4191 rcu_read_unlock();
36c8b586 4192
1da177e4
LT
4193 return retval;
4194}
4195
4196/**
4197 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4198 * @pid: the pid in question.
4199 * @policy: new policy.
4200 * @param: structure containing the new RT priority.
4201 */
4202asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
4203 struct sched_param __user *param)
4204{
c21761f1
JB
4205 /* negative values for policy are not valid */
4206 if (policy < 0)
4207 return -EINVAL;
4208
1da177e4
LT
4209 return do_sched_setscheduler(pid, policy, param);
4210}
4211
4212/**
4213 * sys_sched_setparam - set/change the RT priority of a thread
4214 * @pid: the pid in question.
4215 * @param: structure containing the new RT priority.
4216 */
4217asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
4218{
4219 return do_sched_setscheduler(pid, -1, param);
4220}
4221
4222/**
4223 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4224 * @pid: the pid in question.
4225 */
4226asmlinkage long sys_sched_getscheduler(pid_t pid)
4227{
36c8b586 4228 struct task_struct *p;
1da177e4 4229 int retval = -EINVAL;
1da177e4
LT
4230
4231 if (pid < 0)
4232 goto out_nounlock;
4233
4234 retval = -ESRCH;
4235 read_lock(&tasklist_lock);
4236 p = find_process_by_pid(pid);
4237 if (p) {
4238 retval = security_task_getscheduler(p);
4239 if (!retval)
4240 retval = p->policy;
4241 }
4242 read_unlock(&tasklist_lock);
4243
4244out_nounlock:
4245 return retval;
4246}
4247
4248/**
4249 * sys_sched_getscheduler - get the RT priority of a thread
4250 * @pid: the pid in question.
4251 * @param: structure containing the RT priority.
4252 */
4253asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
4254{
4255 struct sched_param lp;
36c8b586 4256 struct task_struct *p;
1da177e4 4257 int retval = -EINVAL;
1da177e4
LT
4258
4259 if (!param || pid < 0)
4260 goto out_nounlock;
4261
4262 read_lock(&tasklist_lock);
4263 p = find_process_by_pid(pid);
4264 retval = -ESRCH;
4265 if (!p)
4266 goto out_unlock;
4267
4268 retval = security_task_getscheduler(p);
4269 if (retval)
4270 goto out_unlock;
4271
4272 lp.sched_priority = p->rt_priority;
4273 read_unlock(&tasklist_lock);
4274
4275 /*
4276 * This one might sleep, we cannot do it with a spinlock held ...
4277 */
4278 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4279
4280out_nounlock:
4281 return retval;
4282
4283out_unlock:
4284 read_unlock(&tasklist_lock);
4285 return retval;
4286}
4287
4288long sched_setaffinity(pid_t pid, cpumask_t new_mask)
4289{
1da177e4 4290 cpumask_t cpus_allowed;
36c8b586
IM
4291 struct task_struct *p;
4292 int retval;
1da177e4
LT
4293
4294 lock_cpu_hotplug();
4295 read_lock(&tasklist_lock);
4296
4297 p = find_process_by_pid(pid);
4298 if (!p) {
4299 read_unlock(&tasklist_lock);
4300 unlock_cpu_hotplug();
4301 return -ESRCH;
4302 }
4303
4304 /*
4305 * It is not safe to call set_cpus_allowed with the
4306 * tasklist_lock held. We will bump the task_struct's
4307 * usage count and then drop tasklist_lock.
4308 */
4309 get_task_struct(p);
4310 read_unlock(&tasklist_lock);
4311
4312 retval = -EPERM;
4313 if ((current->euid != p->euid) && (current->euid != p->uid) &&
4314 !capable(CAP_SYS_NICE))
4315 goto out_unlock;
4316
e7834f8f
DQ
4317 retval = security_task_setscheduler(p, 0, NULL);
4318 if (retval)
4319 goto out_unlock;
4320
1da177e4
LT
4321 cpus_allowed = cpuset_cpus_allowed(p);
4322 cpus_and(new_mask, new_mask, cpus_allowed);
4323 retval = set_cpus_allowed(p, new_mask);
4324
4325out_unlock:
4326 put_task_struct(p);
4327 unlock_cpu_hotplug();
4328 return retval;
4329}
4330
4331static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4332 cpumask_t *new_mask)
4333{
4334 if (len < sizeof(cpumask_t)) {
4335 memset(new_mask, 0, sizeof(cpumask_t));
4336 } else if (len > sizeof(cpumask_t)) {
4337 len = sizeof(cpumask_t);
4338 }
4339 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4340}
4341
4342/**
4343 * sys_sched_setaffinity - set the cpu affinity of a process
4344 * @pid: pid of the process
4345 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4346 * @user_mask_ptr: user-space pointer to the new cpu mask
4347 */
4348asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
4349 unsigned long __user *user_mask_ptr)
4350{
4351 cpumask_t new_mask;
4352 int retval;
4353
4354 retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
4355 if (retval)
4356 return retval;
4357
4358 return sched_setaffinity(pid, new_mask);
4359}
4360
4361/*
4362 * Represents all cpu's present in the system
4363 * In systems capable of hotplug, this map could dynamically grow
4364 * as new cpu's are detected in the system via any platform specific
4365 * method, such as ACPI for e.g.
4366 */
4367
4cef0c61 4368cpumask_t cpu_present_map __read_mostly;
1da177e4
LT
4369EXPORT_SYMBOL(cpu_present_map);
4370
4371#ifndef CONFIG_SMP
4cef0c61 4372cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
e16b38f7
GB
4373EXPORT_SYMBOL(cpu_online_map);
4374
4cef0c61 4375cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
e16b38f7 4376EXPORT_SYMBOL(cpu_possible_map);
1da177e4
LT
4377#endif
4378
4379long sched_getaffinity(pid_t pid, cpumask_t *mask)
4380{
36c8b586 4381 struct task_struct *p;
1da177e4 4382 int retval;
1da177e4
LT
4383
4384 lock_cpu_hotplug();
4385 read_lock(&tasklist_lock);
4386
4387 retval = -ESRCH;
4388 p = find_process_by_pid(pid);
4389 if (!p)
4390 goto out_unlock;
4391
e7834f8f
DQ
4392 retval = security_task_getscheduler(p);
4393 if (retval)
4394 goto out_unlock;
4395
2f7016d9 4396 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
1da177e4
LT
4397
4398out_unlock:
4399 read_unlock(&tasklist_lock);
4400 unlock_cpu_hotplug();
4401 if (retval)
4402 return retval;
4403
4404 return 0;
4405}
4406
4407/**
4408 * sys_sched_getaffinity - get the cpu affinity of a process
4409 * @pid: pid of the process
4410 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4411 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4412 */
4413asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
4414 unsigned long __user *user_mask_ptr)
4415{
4416 int ret;
4417 cpumask_t mask;
4418
4419 if (len < sizeof(cpumask_t))
4420 return -EINVAL;
4421
4422 ret = sched_getaffinity(pid, &mask);
4423 if (ret < 0)
4424 return ret;
4425
4426 if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
4427 return -EFAULT;
4428
4429 return sizeof(cpumask_t);
4430}
4431
4432/**
4433 * sys_sched_yield - yield the current processor to other threads.
4434 *
72fd4a35 4435 * This function yields the current CPU by moving the calling thread
1da177e4
LT
4436 * to the expired array. If there are no other threads running on this
4437 * CPU then this function will return.
4438 */
4439asmlinkage long sys_sched_yield(void)
4440{
70b97a7f
IM
4441 struct rq *rq = this_rq_lock();
4442 struct prio_array *array = current->array, *target = rq->expired;
1da177e4
LT
4443
4444 schedstat_inc(rq, yld_cnt);
4445 /*
4446 * We implement yielding by moving the task into the expired
4447 * queue.
4448 *
4449 * (special rule: RT tasks will just roundrobin in the active
4450 * array.)
4451 */
4452 if (rt_task(current))
4453 target = rq->active;
4454
5927ad78 4455 if (array->nr_active == 1) {
1da177e4
LT
4456 schedstat_inc(rq, yld_act_empty);
4457 if (!rq->expired->nr_active)
4458 schedstat_inc(rq, yld_both_empty);
4459 } else if (!rq->expired->nr_active)
4460 schedstat_inc(rq, yld_exp_empty);
4461
4462 if (array != target) {
4463 dequeue_task(current, array);
4464 enqueue_task(current, target);
4465 } else
4466 /*
4467 * requeue_task is cheaper so perform that if possible.
4468 */
4469 requeue_task(current, array);
4470
4471 /*
4472 * Since we are going to call schedule() anyway, there's
4473 * no need to preempt or enable interrupts:
4474 */
4475 __release(rq->lock);
8a25d5de 4476 spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
1da177e4
LT
4477 _raw_spin_unlock(&rq->lock);
4478 preempt_enable_no_resched();
4479
4480 schedule();
4481
4482 return 0;
4483}
4484
e7b38404 4485static void __cond_resched(void)
1da177e4 4486{
8e0a43d8
IM
4487#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4488 __might_sleep(__FILE__, __LINE__);
4489#endif
5bbcfd90
IM
4490 /*
4491 * The BKS might be reacquired before we have dropped
4492 * PREEMPT_ACTIVE, which could trigger a second
4493 * cond_resched() call.
4494 */
1da177e4
LT
4495 do {
4496 add_preempt_count(PREEMPT_ACTIVE);
4497 schedule();
4498 sub_preempt_count(PREEMPT_ACTIVE);
4499 } while (need_resched());
4500}
4501
4502int __sched cond_resched(void)
4503{
9414232f
IM
4504 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
4505 system_state == SYSTEM_RUNNING) {
1da177e4
LT
4506 __cond_resched();
4507 return 1;
4508 }
4509 return 0;
4510}
1da177e4
LT
4511EXPORT_SYMBOL(cond_resched);
4512
4513/*
4514 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4515 * call schedule, and on return reacquire the lock.
4516 *
4517 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4518 * operations here to prevent schedule() from being called twice (once via
4519 * spin_unlock(), once by hand).
4520 */
95cdf3b7 4521int cond_resched_lock(spinlock_t *lock)
1da177e4 4522{
6df3cecb
JK
4523 int ret = 0;
4524
1da177e4
LT
4525 if (need_lockbreak(lock)) {
4526 spin_unlock(lock);
4527 cpu_relax();
6df3cecb 4528 ret = 1;
1da177e4
LT
4529 spin_lock(lock);
4530 }
9414232f 4531 if (need_resched() && system_state == SYSTEM_RUNNING) {
8a25d5de 4532 spin_release(&lock->dep_map, 1, _THIS_IP_);
1da177e4
LT
4533 _raw_spin_unlock(lock);
4534 preempt_enable_no_resched();
4535 __cond_resched();
6df3cecb 4536 ret = 1;
1da177e4 4537 spin_lock(lock);
1da177e4 4538 }
6df3cecb 4539 return ret;
1da177e4 4540}
1da177e4
LT
4541EXPORT_SYMBOL(cond_resched_lock);
4542
4543int __sched cond_resched_softirq(void)
4544{
4545 BUG_ON(!in_softirq());
4546
9414232f 4547 if (need_resched() && system_state == SYSTEM_RUNNING) {
de30a2b3
IM
4548 raw_local_irq_disable();
4549 _local_bh_enable();
4550 raw_local_irq_enable();
1da177e4
LT
4551 __cond_resched();
4552 local_bh_disable();
4553 return 1;
4554 }
4555 return 0;
4556}
1da177e4
LT
4557EXPORT_SYMBOL(cond_resched_softirq);
4558
1da177e4
LT
4559/**
4560 * yield - yield the current processor to other threads.
4561 *
72fd4a35 4562 * This is a shortcut for kernel-space yielding - it marks the
1da177e4
LT
4563 * thread runnable and calls sys_sched_yield().
4564 */
4565void __sched yield(void)
4566{
4567 set_current_state(TASK_RUNNING);
4568 sys_sched_yield();
4569}
1da177e4
LT
4570EXPORT_SYMBOL(yield);
4571
4572/*
4573 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4574 * that process accounting knows that this is a task in IO wait state.
4575 *
4576 * But don't do that if it is a deliberate, throttling IO wait (this task
4577 * has set its backing_dev_info: the queue against which it should throttle)
4578 */
4579void __sched io_schedule(void)
4580{
70b97a7f 4581 struct rq *rq = &__raw_get_cpu_var(runqueues);
1da177e4 4582
0ff92245 4583 delayacct_blkio_start();
1da177e4
LT
4584 atomic_inc(&rq->nr_iowait);
4585 schedule();
4586 atomic_dec(&rq->nr_iowait);
0ff92245 4587 delayacct_blkio_end();
1da177e4 4588}
1da177e4
LT
4589EXPORT_SYMBOL(io_schedule);
4590
4591long __sched io_schedule_timeout(long timeout)
4592{
70b97a7f 4593 struct rq *rq = &__raw_get_cpu_var(runqueues);
1da177e4
LT
4594 long ret;
4595
0ff92245 4596 delayacct_blkio_start();
1da177e4
LT
4597 atomic_inc(&rq->nr_iowait);
4598 ret = schedule_timeout(timeout);
4599 atomic_dec(&rq->nr_iowait);
0ff92245 4600 delayacct_blkio_end();
1da177e4
LT
4601 return ret;
4602}
4603
4604/**
4605 * sys_sched_get_priority_max - return maximum RT priority.
4606 * @policy: scheduling class.
4607 *
4608 * this syscall returns the maximum rt_priority that can be used
4609 * by a given scheduling class.
4610 */
4611asmlinkage long sys_sched_get_priority_max(int policy)
4612{
4613 int ret = -EINVAL;
4614
4615 switch (policy) {
4616 case SCHED_FIFO:
4617 case SCHED_RR:
4618 ret = MAX_USER_RT_PRIO-1;
4619 break;
4620 case SCHED_NORMAL:
b0a9499c 4621 case SCHED_BATCH:
1da177e4
LT
4622 ret = 0;
4623 break;
4624 }
4625 return ret;
4626}
4627
4628/**
4629 * sys_sched_get_priority_min - return minimum RT priority.
4630 * @policy: scheduling class.
4631 *
4632 * this syscall returns the minimum rt_priority that can be used
4633 * by a given scheduling class.
4634 */
4635asmlinkage long sys_sched_get_priority_min(int policy)
4636{
4637 int ret = -EINVAL;
4638
4639 switch (policy) {
4640 case SCHED_FIFO:
4641 case SCHED_RR:
4642 ret = 1;
4643 break;
4644 case SCHED_NORMAL:
b0a9499c 4645 case SCHED_BATCH:
1da177e4
LT
4646 ret = 0;
4647 }
4648 return ret;
4649}
4650
4651/**
4652 * sys_sched_rr_get_interval - return the default timeslice of a process.
4653 * @pid: pid of the process.
4654 * @interval: userspace pointer to the timeslice value.
4655 *
4656 * this syscall writes the default timeslice value of a given process
4657 * into the user-space timespec buffer. A value of '0' means infinity.
4658 */
4659asmlinkage
4660long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
4661{
36c8b586 4662 struct task_struct *p;
1da177e4
LT
4663 int retval = -EINVAL;
4664 struct timespec t;
1da177e4
LT
4665
4666 if (pid < 0)
4667 goto out_nounlock;
4668
4669 retval = -ESRCH;
4670 read_lock(&tasklist_lock);
4671 p = find_process_by_pid(pid);
4672 if (!p)
4673 goto out_unlock;
4674
4675 retval = security_task_getscheduler(p);
4676 if (retval)
4677 goto out_unlock;
4678
b78709cf 4679 jiffies_to_timespec(p->policy == SCHED_FIFO ?
1da177e4
LT
4680 0 : task_timeslice(p), &t);
4681 read_unlock(&tasklist_lock);
4682 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4683out_nounlock:
4684 return retval;
4685out_unlock:
4686 read_unlock(&tasklist_lock);
4687 return retval;
4688}
4689
2ed6e34f 4690static const char stat_nam[] = "RSDTtZX";
36c8b586
IM
4691
4692static void show_task(struct task_struct *p)
1da177e4 4693{
1da177e4 4694 unsigned long free = 0;
36c8b586 4695 unsigned state;
1da177e4 4696
1da177e4 4697 state = p->state ? __ffs(p->state) + 1 : 0;
2ed6e34f
AM
4698 printk("%-13.13s %c", p->comm,
4699 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
1da177e4
LT
4700#if (BITS_PER_LONG == 32)
4701 if (state == TASK_RUNNING)
4702 printk(" running ");
4703 else
4704 printk(" %08lX ", thread_saved_pc(p));
4705#else
4706 if (state == TASK_RUNNING)
4707 printk(" running task ");
4708 else
4709 printk(" %016lx ", thread_saved_pc(p));
4710#endif
4711#ifdef CONFIG_DEBUG_STACK_USAGE
4712 {
10ebffde 4713 unsigned long *n = end_of_stack(p);
1da177e4
LT
4714 while (!*n)
4715 n++;
10ebffde 4716 free = (unsigned long)n - (unsigned long)end_of_stack(p);
1da177e4
LT
4717 }
4718#endif
35f6f753 4719 printk("%5lu %5d %6d", free, p->pid, p->parent->pid);
1da177e4
LT
4720 if (!p->mm)
4721 printk(" (L-TLB)\n");
4722 else
4723 printk(" (NOTLB)\n");
4724
4725 if (state != TASK_RUNNING)
4726 show_stack(p, NULL);
4727}
4728
e59e2ae2 4729void show_state_filter(unsigned long state_filter)
1da177e4 4730{
36c8b586 4731 struct task_struct *g, *p;
1da177e4
LT
4732
4733#if (BITS_PER_LONG == 32)
4734 printk("\n"
301827ac
CC
4735 " free sibling\n");
4736 printk(" task PC stack pid father child younger older\n");
1da177e4
LT
4737#else
4738 printk("\n"
301827ac
CC
4739 " free sibling\n");
4740 printk(" task PC stack pid father child younger older\n");
1da177e4
LT
4741#endif
4742 read_lock(&tasklist_lock);
4743 do_each_thread(g, p) {
4744 /*
4745 * reset the NMI-timeout, listing all files on a slow
4746 * console might take alot of time:
4747 */
4748 touch_nmi_watchdog();
39bc89fd 4749 if (!state_filter || (p->state & state_filter))
e59e2ae2 4750 show_task(p);
1da177e4
LT
4751 } while_each_thread(g, p);
4752
4753 read_unlock(&tasklist_lock);
e59e2ae2
IM
4754 /*
4755 * Only show locks if all tasks are dumped:
4756 */
4757 if (state_filter == -1)
4758 debug_show_all_locks();
1da177e4
LT
4759}
4760
f340c0d1
IM
4761/**
4762 * init_idle - set up an idle thread for a given CPU
4763 * @idle: task in question
4764 * @cpu: cpu the idle task belongs to
4765 *
4766 * NOTE: this function does not set the idle thread's NEED_RESCHED
4767 * flag, to make booting more robust.
4768 */
5c1e1767 4769void __cpuinit init_idle(struct task_struct *idle, int cpu)
1da177e4 4770{
70b97a7f 4771 struct rq *rq = cpu_rq(cpu);
1da177e4
LT
4772 unsigned long flags;
4773
81c29a85 4774 idle->timestamp = sched_clock();
1da177e4
LT
4775 idle->sleep_avg = 0;
4776 idle->array = NULL;
b29739f9 4777 idle->prio = idle->normal_prio = MAX_PRIO;
1da177e4
LT
4778 idle->state = TASK_RUNNING;
4779 idle->cpus_allowed = cpumask_of_cpu(cpu);
4780 set_task_cpu(idle, cpu);
4781
4782 spin_lock_irqsave(&rq->lock, flags);
4783 rq->curr = rq->idle = idle;
4866cde0
NP
4784#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4785 idle->oncpu = 1;
4786#endif
1da177e4
LT
4787 spin_unlock_irqrestore(&rq->lock, flags);
4788
4789 /* Set the preempt count _outside_ the spinlocks! */
4790#if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
a1261f54 4791 task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
1da177e4 4792#else
a1261f54 4793 task_thread_info(idle)->preempt_count = 0;
1da177e4
LT
4794#endif
4795}
4796
4797/*
4798 * In a system that switches off the HZ timer nohz_cpu_mask
4799 * indicates which cpus entered this state. This is used
4800 * in the rcu update to wait only for active cpus. For system
4801 * which do not switch off the HZ timer nohz_cpu_mask should
4802 * always be CPU_MASK_NONE.
4803 */
4804cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
4805
4806#ifdef CONFIG_SMP
4807/*
4808 * This is how migration works:
4809 *
70b97a7f 4810 * 1) we queue a struct migration_req structure in the source CPU's
1da177e4
LT
4811 * runqueue and wake up that CPU's migration thread.
4812 * 2) we down() the locked semaphore => thread blocks.
4813 * 3) migration thread wakes up (implicitly it forces the migrated
4814 * thread off the CPU)
4815 * 4) it gets the migration request and checks whether the migrated
4816 * task is still in the wrong runqueue.
4817 * 5) if it's in the wrong runqueue then the migration thread removes
4818 * it and puts it into the right queue.
4819 * 6) migration thread up()s the semaphore.
4820 * 7) we wake up and the migration is done.
4821 */
4822
4823/*
4824 * Change a given task's CPU affinity. Migrate the thread to a
4825 * proper CPU and schedule it away if the CPU it's executing on
4826 * is removed from the allowed bitmask.
4827 *
4828 * NOTE: the caller must have a valid reference to the task, the
4829 * task must not exit() & deallocate itself prematurely. The
4830 * call is not atomic; no spinlocks may be held.
4831 */
36c8b586 4832int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
1da177e4 4833{
70b97a7f 4834 struct migration_req req;
1da177e4 4835 unsigned long flags;
70b97a7f 4836 struct rq *rq;
48f24c4d 4837 int ret = 0;
1da177e4
LT
4838
4839 rq = task_rq_lock(p, &flags);
4840 if (!cpus_intersects(new_mask, cpu_online_map)) {
4841 ret = -EINVAL;
4842 goto out;
4843 }
4844
4845 p->cpus_allowed = new_mask;
4846 /* Can the task run on the task's current CPU? If so, we're done */
4847 if (cpu_isset(task_cpu(p), new_mask))
4848 goto out;
4849
4850 if (migrate_task(p, any_online_cpu(new_mask), &req)) {
4851 /* Need help from migration thread: drop lock and wait. */
4852 task_rq_unlock(rq, &flags);
4853 wake_up_process(rq->migration_thread);
4854 wait_for_completion(&req.done);
4855 tlb_migrate_finish(p->mm);
4856 return 0;
4857 }
4858out:
4859 task_rq_unlock(rq, &flags);
48f24c4d 4860
1da177e4
LT
4861 return ret;
4862}
1da177e4
LT
4863EXPORT_SYMBOL_GPL(set_cpus_allowed);
4864
4865/*
4866 * Move (not current) task off this cpu, onto dest cpu. We're doing
4867 * this because either it can't run here any more (set_cpus_allowed()
4868 * away from this CPU, or CPU going down), or because we're
4869 * attempting to rebalance this task on exec (sched_exec).
4870 *
4871 * So we race with normal scheduler movements, but that's OK, as long
4872 * as the task is no longer on this CPU.
efc30814
KK
4873 *
4874 * Returns non-zero if task was successfully migrated.
1da177e4 4875 */
efc30814 4876static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
1da177e4 4877{
70b97a7f 4878 struct rq *rq_dest, *rq_src;
efc30814 4879 int ret = 0;
1da177e4
LT
4880
4881 if (unlikely(cpu_is_offline(dest_cpu)))
efc30814 4882 return ret;
1da177e4
LT
4883
4884 rq_src = cpu_rq(src_cpu);
4885 rq_dest = cpu_rq(dest_cpu);
4886
4887 double_rq_lock(rq_src, rq_dest);
4888 /* Already moved. */
4889 if (task_cpu(p) != src_cpu)
4890 goto out;
4891 /* Affinity changed (again). */
4892 if (!cpu_isset(dest_cpu, p->cpus_allowed))
4893 goto out;
4894
4895 set_task_cpu(p, dest_cpu);
4896 if (p->array) {
4897 /*
4898 * Sync timestamp with rq_dest's before activating.
4899 * The same thing could be achieved by doing this step
4900 * afterwards, and pretending it was a local activate.
4901 * This way is cleaner and logically correct.
4902 */
b18ec803
MG
4903 p->timestamp = p->timestamp - rq_src->most_recent_timestamp
4904 + rq_dest->most_recent_timestamp;
1da177e4 4905 deactivate_task(p, rq_src);
0a565f79 4906 __activate_task(p, rq_dest);
1da177e4
LT
4907 if (TASK_PREEMPTS_CURR(p, rq_dest))
4908 resched_task(rq_dest->curr);
4909 }
efc30814 4910 ret = 1;
1da177e4
LT
4911out:
4912 double_rq_unlock(rq_src, rq_dest);
efc30814 4913 return ret;
1da177e4
LT
4914}
4915
4916/*
4917 * migration_thread - this is a highprio system thread that performs
4918 * thread migration by bumping thread off CPU then 'pushing' onto
4919 * another runqueue.
4920 */
95cdf3b7 4921static int migration_thread(void *data)
1da177e4 4922{
1da177e4 4923 int cpu = (long)data;
70b97a7f 4924 struct rq *rq;
1da177e4
LT
4925
4926 rq = cpu_rq(cpu);
4927 BUG_ON(rq->migration_thread != current);
4928
4929 set_current_state(TASK_INTERRUPTIBLE);
4930 while (!kthread_should_stop()) {
70b97a7f 4931 struct migration_req *req;
1da177e4 4932 struct list_head *head;
1da177e4 4933
3e1d1d28 4934 try_to_freeze();
1da177e4
LT
4935
4936 spin_lock_irq(&rq->lock);
4937
4938 if (cpu_is_offline(cpu)) {
4939 spin_unlock_irq(&rq->lock);
4940 goto wait_to_die;
4941 }
4942
4943 if (rq->active_balance) {
4944 active_load_balance(rq, cpu);
4945 rq->active_balance = 0;
4946 }
4947
4948 head = &rq->migration_queue;
4949
4950 if (list_empty(head)) {
4951 spin_unlock_irq(&rq->lock);
4952 schedule();
4953 set_current_state(TASK_INTERRUPTIBLE);
4954 continue;
4955 }
70b97a7f 4956 req = list_entry(head->next, struct migration_req, list);
1da177e4
LT
4957 list_del_init(head->next);
4958
674311d5
NP
4959 spin_unlock(&rq->lock);
4960 __migrate_task(req->task, cpu, req->dest_cpu);
4961 local_irq_enable();
1da177e4
LT
4962
4963 complete(&req->done);
4964 }
4965 __set_current_state(TASK_RUNNING);
4966 return 0;
4967
4968wait_to_die:
4969 /* Wait for kthread_stop */
4970 set_current_state(TASK_INTERRUPTIBLE);
4971 while (!kthread_should_stop()) {
4972 schedule();
4973 set_current_state(TASK_INTERRUPTIBLE);
4974 }
4975 __set_current_state(TASK_RUNNING);
4976 return 0;
4977}
4978
4979#ifdef CONFIG_HOTPLUG_CPU
054b9108
KK
4980/*
4981 * Figure out where task on dead CPU should go, use force if neccessary.
4982 * NOTE: interrupts should be disabled by the caller
4983 */
48f24c4d 4984static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
1da177e4 4985{
efc30814 4986 unsigned long flags;
1da177e4 4987 cpumask_t mask;
70b97a7f
IM
4988 struct rq *rq;
4989 int dest_cpu;
1da177e4 4990
efc30814 4991restart:
1da177e4
LT
4992 /* On same node? */
4993 mask = node_to_cpumask(cpu_to_node(dead_cpu));
48f24c4d 4994 cpus_and(mask, mask, p->cpus_allowed);
1da177e4
LT
4995 dest_cpu = any_online_cpu(mask);
4996
4997 /* On any allowed CPU? */
4998 if (dest_cpu == NR_CPUS)
48f24c4d 4999 dest_cpu = any_online_cpu(p->cpus_allowed);
1da177e4
LT
5000
5001 /* No more Mr. Nice Guy. */
5002 if (dest_cpu == NR_CPUS) {
48f24c4d
IM
5003 rq = task_rq_lock(p, &flags);
5004 cpus_setall(p->cpus_allowed);
5005 dest_cpu = any_online_cpu(p->cpus_allowed);
efc30814 5006 task_rq_unlock(rq, &flags);
1da177e4
LT
5007
5008 /*
5009 * Don't tell them about moving exiting tasks or
5010 * kernel threads (both mm NULL), since they never
5011 * leave kernel.
5012 */
48f24c4d 5013 if (p->mm && printk_ratelimit())
1da177e4
LT
5014 printk(KERN_INFO "process %d (%s) no "
5015 "longer affine to cpu%d\n",
48f24c4d 5016 p->pid, p->comm, dead_cpu);
1da177e4 5017 }
48f24c4d 5018 if (!__migrate_task(p, dead_cpu, dest_cpu))
efc30814 5019 goto restart;
1da177e4
LT
5020}
5021
5022/*
5023 * While a dead CPU has no uninterruptible tasks queued at this point,
5024 * it might still have a nonzero ->nr_uninterruptible counter, because
5025 * for performance reasons the counter is not stricly tracking tasks to
5026 * their home CPUs. So we just add the counter to another CPU's counter,
5027 * to keep the global sum constant after CPU-down:
5028 */
70b97a7f 5029static void migrate_nr_uninterruptible(struct rq *rq_src)
1da177e4 5030{
70b97a7f 5031 struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL));
1da177e4
LT
5032 unsigned long flags;
5033
5034 local_irq_save(flags);
5035 double_rq_lock(rq_src, rq_dest);
5036 rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5037 rq_src->nr_uninterruptible = 0;
5038 double_rq_unlock(rq_src, rq_dest);
5039 local_irq_restore(flags);
5040}
5041
5042/* Run through task list and migrate tasks from the dead cpu. */
5043static void migrate_live_tasks(int src_cpu)
5044{
48f24c4d 5045 struct task_struct *p, *t;
1da177e4
LT
5046
5047 write_lock_irq(&tasklist_lock);
5048
48f24c4d
IM
5049 do_each_thread(t, p) {
5050 if (p == current)
1da177e4
LT
5051 continue;
5052
48f24c4d
IM
5053 if (task_cpu(p) == src_cpu)
5054 move_task_off_dead_cpu(src_cpu, p);
5055 } while_each_thread(t, p);
1da177e4
LT
5056
5057 write_unlock_irq(&tasklist_lock);
5058}
5059
5060/* Schedules idle task to be the next runnable task on current CPU.
5061 * It does so by boosting its priority to highest possible and adding it to
48f24c4d 5062 * the _front_ of the runqueue. Used by CPU offline code.
1da177e4
LT
5063 */
5064void sched_idle_next(void)
5065{
48f24c4d 5066 int this_cpu = smp_processor_id();
70b97a7f 5067 struct rq *rq = cpu_rq(this_cpu);
1da177e4
LT
5068 struct task_struct *p = rq->idle;
5069 unsigned long flags;
5070
5071 /* cpu has to be offline */
48f24c4d 5072 BUG_ON(cpu_online(this_cpu));
1da177e4 5073
48f24c4d
IM
5074 /*
5075 * Strictly not necessary since rest of the CPUs are stopped by now
5076 * and interrupts disabled on the current cpu.
1da177e4
LT
5077 */
5078 spin_lock_irqsave(&rq->lock, flags);
5079
5080 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
48f24c4d
IM
5081
5082 /* Add idle task to the _front_ of its priority queue: */
1da177e4
LT
5083 __activate_idle_task(p, rq);
5084
5085 spin_unlock_irqrestore(&rq->lock, flags);
5086}
5087
48f24c4d
IM
5088/*
5089 * Ensures that the idle task is using init_mm right before its cpu goes
1da177e4
LT
5090 * offline.
5091 */
5092void idle_task_exit(void)
5093{
5094 struct mm_struct *mm = current->active_mm;
5095
5096 BUG_ON(cpu_online(smp_processor_id()));
5097
5098 if (mm != &init_mm)
5099 switch_mm(mm, &init_mm, current);
5100 mmdrop(mm);
5101}
5102
054b9108 5103/* called under rq->lock with disabled interrupts */
36c8b586 5104static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
1da177e4 5105{
70b97a7f 5106 struct rq *rq = cpu_rq(dead_cpu);
1da177e4
LT
5107
5108 /* Must be exiting, otherwise would be on tasklist. */
48f24c4d 5109 BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
1da177e4
LT
5110
5111 /* Cannot have done final schedule yet: would have vanished. */
c394cc9f 5112 BUG_ON(p->state == TASK_DEAD);
1da177e4 5113
48f24c4d 5114 get_task_struct(p);
1da177e4
LT
5115
5116 /*
5117 * Drop lock around migration; if someone else moves it,
5118 * that's OK. No task can be added to this CPU, so iteration is
5119 * fine.
054b9108 5120 * NOTE: interrupts should be left disabled --dev@
1da177e4 5121 */
054b9108 5122 spin_unlock(&rq->lock);
48f24c4d 5123 move_task_off_dead_cpu(dead_cpu, p);
054b9108 5124 spin_lock(&rq->lock);
1da177e4 5125
48f24c4d 5126 put_task_struct(p);
1da177e4
LT
5127}
5128
5129/* release_task() removes task from tasklist, so we won't find dead tasks. */
5130static void migrate_dead_tasks(unsigned int dead_cpu)
5131{
70b97a7f 5132 struct rq *rq = cpu_rq(dead_cpu);
48f24c4d 5133 unsigned int arr, i;
1da177e4
LT
5134
5135 for (arr = 0; arr < 2; arr++) {
5136 for (i = 0; i < MAX_PRIO; i++) {
5137 struct list_head *list = &rq->arrays[arr].queue[i];
48f24c4d 5138
1da177e4 5139 while (!list_empty(list))
36c8b586
IM
5140 migrate_dead(dead_cpu, list_entry(list->next,
5141 struct task_struct, run_list));
1da177e4
LT
5142 }
5143 }
5144}
5145#endif /* CONFIG_HOTPLUG_CPU */
5146
5147/*
5148 * migration_call - callback that gets triggered when a CPU is added.
5149 * Here we can start up the necessary migration thread for the new CPU.
5150 */
48f24c4d
IM
5151static int __cpuinit
5152migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
1da177e4 5153{
1da177e4 5154 struct task_struct *p;
48f24c4d 5155 int cpu = (long)hcpu;
1da177e4 5156 unsigned long flags;
70b97a7f 5157 struct rq *rq;
1da177e4
LT
5158
5159 switch (action) {
5160 case CPU_UP_PREPARE:
5161 p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
5162 if (IS_ERR(p))
5163 return NOTIFY_BAD;
5164 p->flags |= PF_NOFREEZE;
5165 kthread_bind(p, cpu);
5166 /* Must be high prio: stop_machine expects to yield to it. */
5167 rq = task_rq_lock(p, &flags);
5168 __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1);
5169 task_rq_unlock(rq, &flags);
5170 cpu_rq(cpu)->migration_thread = p;
5171 break;
48f24c4d 5172
1da177e4
LT
5173 case CPU_ONLINE:
5174 /* Strictly unneccessary, as first user will wake it. */
5175 wake_up_process(cpu_rq(cpu)->migration_thread);
5176 break;
48f24c4d 5177
1da177e4
LT
5178#ifdef CONFIG_HOTPLUG_CPU
5179 case CPU_UP_CANCELED:
fc75cdfa
HC
5180 if (!cpu_rq(cpu)->migration_thread)
5181 break;
1da177e4 5182 /* Unbind it from offline cpu so it can run. Fall thru. */
a4c4af7c
HC
5183 kthread_bind(cpu_rq(cpu)->migration_thread,
5184 any_online_cpu(cpu_online_map));
1da177e4
LT
5185 kthread_stop(cpu_rq(cpu)->migration_thread);
5186 cpu_rq(cpu)->migration_thread = NULL;
5187 break;
48f24c4d 5188
1da177e4
LT
5189 case CPU_DEAD:
5190 migrate_live_tasks(cpu);
5191 rq = cpu_rq(cpu);
5192 kthread_stop(rq->migration_thread);
5193 rq->migration_thread = NULL;
5194 /* Idle task back to normal (off runqueue, low prio) */
5195 rq = task_rq_lock(rq->idle, &flags);
5196 deactivate_task(rq->idle, rq);
5197 rq->idle->static_prio = MAX_PRIO;
5198 __setscheduler(rq->idle, SCHED_NORMAL, 0);
5199 migrate_dead_tasks(cpu);
5200 task_rq_unlock(rq, &flags);
5201 migrate_nr_uninterruptible(rq);
5202 BUG_ON(rq->nr_running != 0);
5203
5204 /* No need to migrate the tasks: it was best-effort if
5205 * they didn't do lock_cpu_hotplug(). Just wake up
5206 * the requestors. */
5207 spin_lock_irq(&rq->lock);
5208 while (!list_empty(&rq->migration_queue)) {
70b97a7f
IM
5209 struct migration_req *req;
5210
1da177e4 5211 req = list_entry(rq->migration_queue.next,
70b97a7f 5212 struct migration_req, list);
1da177e4
LT
5213 list_del_init(&req->list);
5214 complete(&req->done);
5215 }
5216 spin_unlock_irq(&rq->lock);
5217 break;
5218#endif
5219 }
5220 return NOTIFY_OK;
5221}
5222
5223/* Register at highest priority so that task migration (migrate_all_tasks)
5224 * happens before everything else.
5225 */
26c2143b 5226static struct notifier_block __cpuinitdata migration_notifier = {
1da177e4
LT
5227 .notifier_call = migration_call,
5228 .priority = 10
5229};
5230
5231int __init migration_init(void)
5232{
5233 void *cpu = (void *)(long)smp_processor_id();
07dccf33 5234 int err;
48f24c4d
IM
5235
5236 /* Start one for the boot CPU: */
07dccf33
AM
5237 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5238 BUG_ON(err == NOTIFY_BAD);
1da177e4
LT
5239 migration_call(&migration_notifier, CPU_ONLINE, cpu);
5240 register_cpu_notifier(&migration_notifier);
48f24c4d 5241
1da177e4
LT
5242 return 0;
5243}
5244#endif
5245
5246#ifdef CONFIG_SMP
1a20ff27 5247#undef SCHED_DOMAIN_DEBUG
1da177e4
LT
5248#ifdef SCHED_DOMAIN_DEBUG
5249static void sched_domain_debug(struct sched_domain *sd, int cpu)
5250{
5251 int level = 0;
5252
41c7ce9a
NP
5253 if (!sd) {
5254 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5255 return;
5256 }
5257
1da177e4
LT
5258 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5259
5260 do {
5261 int i;
5262 char str[NR_CPUS];
5263 struct sched_group *group = sd->groups;
5264 cpumask_t groupmask;
5265
5266 cpumask_scnprintf(str, NR_CPUS, sd->span);
5267 cpus_clear(groupmask);
5268
5269 printk(KERN_DEBUG);
5270 for (i = 0; i < level + 1; i++)
5271 printk(" ");
5272 printk("domain %d: ", level);
5273
5274 if (!(sd->flags & SD_LOAD_BALANCE)) {
5275 printk("does not load-balance\n");
5276 if (sd->parent)
33859f7f
MOS
5277 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5278 " has parent");
1da177e4
LT
5279 break;
5280 }
5281
5282 printk("span %s\n", str);
5283
5284 if (!cpu_isset(cpu, sd->span))
33859f7f
MOS
5285 printk(KERN_ERR "ERROR: domain->span does not contain "
5286 "CPU%d\n", cpu);
1da177e4 5287 if (!cpu_isset(cpu, group->cpumask))
33859f7f
MOS
5288 printk(KERN_ERR "ERROR: domain->groups does not contain"
5289 " CPU%d\n", cpu);
1da177e4
LT
5290
5291 printk(KERN_DEBUG);
5292 for (i = 0; i < level + 2; i++)
5293 printk(" ");
5294 printk("groups:");
5295 do {
5296 if (!group) {
5297 printk("\n");
5298 printk(KERN_ERR "ERROR: group is NULL\n");
5299 break;
5300 }
5301
5302 if (!group->cpu_power) {
5303 printk("\n");
33859f7f
MOS
5304 printk(KERN_ERR "ERROR: domain->cpu_power not "
5305 "set\n");
1da177e4
LT
5306 }
5307
5308 if (!cpus_weight(group->cpumask)) {
5309 printk("\n");
5310 printk(KERN_ERR "ERROR: empty group\n");
5311 }
5312
5313 if (cpus_intersects(groupmask, group->cpumask)) {
5314 printk("\n");
5315 printk(KERN_ERR "ERROR: repeated CPUs\n");
5316 }
5317
5318 cpus_or(groupmask, groupmask, group->cpumask);
5319
5320 cpumask_scnprintf(str, NR_CPUS, group->cpumask);
5321 printk(" %s", str);
5322
5323 group = group->next;
5324 } while (group != sd->groups);
5325 printk("\n");
5326
5327 if (!cpus_equal(sd->span, groupmask))
33859f7f
MOS
5328 printk(KERN_ERR "ERROR: groups don't span "
5329 "domain->span\n");
1da177e4
LT
5330
5331 level++;
5332 sd = sd->parent;
33859f7f
MOS
5333 if (!sd)
5334 continue;
1da177e4 5335
33859f7f
MOS
5336 if (!cpus_subset(groupmask, sd->span))
5337 printk(KERN_ERR "ERROR: parent span is not a superset "
5338 "of domain->span\n");
1da177e4
LT
5339
5340 } while (sd);
5341}
5342#else
48f24c4d 5343# define sched_domain_debug(sd, cpu) do { } while (0)
1da177e4
LT
5344#endif
5345
1a20ff27 5346static int sd_degenerate(struct sched_domain *sd)
245af2c7
SS
5347{
5348 if (cpus_weight(sd->span) == 1)
5349 return 1;
5350
5351 /* Following flags need at least 2 groups */
5352 if (sd->flags & (SD_LOAD_BALANCE |
5353 SD_BALANCE_NEWIDLE |
5354 SD_BALANCE_FORK |
89c4710e
SS
5355 SD_BALANCE_EXEC |
5356 SD_SHARE_CPUPOWER |
5357 SD_SHARE_PKG_RESOURCES)) {
245af2c7
SS
5358 if (sd->groups != sd->groups->next)
5359 return 0;
5360 }
5361
5362 /* Following flags don't use groups */
5363 if (sd->flags & (SD_WAKE_IDLE |
5364 SD_WAKE_AFFINE |
5365 SD_WAKE_BALANCE))
5366 return 0;
5367
5368 return 1;
5369}
5370
48f24c4d
IM
5371static int
5372sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
245af2c7
SS
5373{
5374 unsigned long cflags = sd->flags, pflags = parent->flags;
5375
5376 if (sd_degenerate(parent))
5377 return 1;
5378
5379 if (!cpus_equal(sd->span, parent->span))
5380 return 0;
5381
5382 /* Does parent contain flags not in child? */
5383 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5384 if (cflags & SD_WAKE_AFFINE)
5385 pflags &= ~SD_WAKE_BALANCE;
5386 /* Flags needing groups don't count if only 1 group in parent */
5387 if (parent->groups == parent->groups->next) {
5388 pflags &= ~(SD_LOAD_BALANCE |
5389 SD_BALANCE_NEWIDLE |
5390 SD_BALANCE_FORK |
89c4710e
SS
5391 SD_BALANCE_EXEC |
5392 SD_SHARE_CPUPOWER |
5393 SD_SHARE_PKG_RESOURCES);
245af2c7
SS
5394 }
5395 if (~cflags & pflags)
5396 return 0;
5397
5398 return 1;
5399}
5400
1da177e4
LT
5401/*
5402 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5403 * hold the hotplug lock.
5404 */
9c1cfda2 5405static void cpu_attach_domain(struct sched_domain *sd, int cpu)
1da177e4 5406{
70b97a7f 5407 struct rq *rq = cpu_rq(cpu);
245af2c7
SS
5408 struct sched_domain *tmp;
5409
5410 /* Remove the sched domains which do not contribute to scheduling. */
5411 for (tmp = sd; tmp; tmp = tmp->parent) {
5412 struct sched_domain *parent = tmp->parent;
5413 if (!parent)
5414 break;
1a848870 5415 if (sd_parent_degenerate(tmp, parent)) {
245af2c7 5416 tmp->parent = parent->parent;
1a848870
SS
5417 if (parent->parent)
5418 parent->parent->child = tmp;
5419 }
245af2c7
SS
5420 }
5421
1a848870 5422 if (sd && sd_degenerate(sd)) {
245af2c7 5423 sd = sd->parent;
1a848870
SS
5424 if (sd)
5425 sd->child = NULL;
5426 }
1da177e4
LT
5427
5428 sched_domain_debug(sd, cpu);
5429
674311d5 5430 rcu_assign_pointer(rq->sd, sd);
1da177e4
LT
5431}
5432
5433/* cpus with isolated domains */
67af63a6 5434static cpumask_t cpu_isolated_map = CPU_MASK_NONE;
1da177e4
LT
5435
5436/* Setup the mask of cpus configured for isolated domains */
5437static int __init isolated_cpu_setup(char *str)
5438{
5439 int ints[NR_CPUS], i;
5440
5441 str = get_options(str, ARRAY_SIZE(ints), ints);
5442 cpus_clear(cpu_isolated_map);
5443 for (i = 1; i <= ints[0]; i++)
5444 if (ints[i] < NR_CPUS)
5445 cpu_set(ints[i], cpu_isolated_map);
5446 return 1;
5447}
5448
5449__setup ("isolcpus=", isolated_cpu_setup);
5450
5451/*
6711cab4
SS
5452 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5453 * to a function which identifies what group(along with sched group) a CPU
5454 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5455 * (due to the fact that we keep track of groups covered with a cpumask_t).
1da177e4
LT
5456 *
5457 * init_sched_build_groups will build a circular linked list of the groups
5458 * covered by the given span, and will set each group's ->cpumask correctly,
5459 * and ->cpu_power to 0.
5460 */
a616058b 5461static void
6711cab4
SS
5462init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map,
5463 int (*group_fn)(int cpu, const cpumask_t *cpu_map,
5464 struct sched_group **sg))
1da177e4
LT
5465{
5466 struct sched_group *first = NULL, *last = NULL;
5467 cpumask_t covered = CPU_MASK_NONE;
5468 int i;
5469
5470 for_each_cpu_mask(i, span) {
6711cab4
SS
5471 struct sched_group *sg;
5472 int group = group_fn(i, cpu_map, &sg);
1da177e4
LT
5473 int j;
5474
5475 if (cpu_isset(i, covered))
5476 continue;
5477
5478 sg->cpumask = CPU_MASK_NONE;
5479 sg->cpu_power = 0;
5480
5481 for_each_cpu_mask(j, span) {
6711cab4 5482 if (group_fn(j, cpu_map, NULL) != group)
1da177e4
LT
5483 continue;
5484
5485 cpu_set(j, covered);
5486 cpu_set(j, sg->cpumask);
5487 }
5488 if (!first)
5489 first = sg;
5490 if (last)
5491 last->next = sg;
5492 last = sg;
5493 }
5494 last->next = first;
5495}
5496
9c1cfda2 5497#define SD_NODES_PER_DOMAIN 16
1da177e4 5498
198e2f18 5499/*
5500 * Self-tuning task migration cost measurement between source and target CPUs.
5501 *
5502 * This is done by measuring the cost of manipulating buffers of varying
5503 * sizes. For a given buffer-size here are the steps that are taken:
5504 *
5505 * 1) the source CPU reads+dirties a shared buffer
5506 * 2) the target CPU reads+dirties the same shared buffer
5507 *
5508 * We measure how long they take, in the following 4 scenarios:
5509 *
5510 * - source: CPU1, target: CPU2 | cost1
5511 * - source: CPU2, target: CPU1 | cost2
5512 * - source: CPU1, target: CPU1 | cost3
5513 * - source: CPU2, target: CPU2 | cost4
5514 *
5515 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5516 * the cost of migration.
5517 *
5518 * We then start off from a small buffer-size and iterate up to larger
5519 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5520 * doing a maximum search for the cost. (The maximum cost for a migration
5521 * normally occurs when the working set size is around the effective cache
5522 * size.)
5523 */
5524#define SEARCH_SCOPE 2
5525#define MIN_CACHE_SIZE (64*1024U)
5526#define DEFAULT_CACHE_SIZE (5*1024*1024U)
70b4d63e 5527#define ITERATIONS 1
198e2f18 5528#define SIZE_THRESH 130
5529#define COST_THRESH 130
5530
5531/*
5532 * The migration cost is a function of 'domain distance'. Domain
5533 * distance is the number of steps a CPU has to iterate down its
5534 * domain tree to share a domain with the other CPU. The farther
5535 * two CPUs are from each other, the larger the distance gets.
5536 *
5537 * Note that we use the distance only to cache measurement results,
5538 * the distance value is not used numerically otherwise. When two
5539 * CPUs have the same distance it is assumed that the migration
5540 * cost is the same. (this is a simplification but quite practical)
5541 */
5542#define MAX_DOMAIN_DISTANCE 32
5543
5544static unsigned long long migration_cost[MAX_DOMAIN_DISTANCE] =
4bbf39c2
IM
5545 { [ 0 ... MAX_DOMAIN_DISTANCE-1 ] =
5546/*
5547 * Architectures may override the migration cost and thus avoid
5548 * boot-time calibration. Unit is nanoseconds. Mostly useful for
5549 * virtualized hardware:
5550 */
5551#ifdef CONFIG_DEFAULT_MIGRATION_COST
5552 CONFIG_DEFAULT_MIGRATION_COST
5553#else
5554 -1LL
5555#endif
5556};
198e2f18 5557
5558/*
5559 * Allow override of migration cost - in units of microseconds.
5560 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5561 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5562 */
5563static int __init migration_cost_setup(char *str)
5564{
5565 int ints[MAX_DOMAIN_DISTANCE+1], i;
5566
5567 str = get_options(str, ARRAY_SIZE(ints), ints);
5568
5569 printk("#ints: %d\n", ints[0]);
5570 for (i = 1; i <= ints[0]; i++) {
5571 migration_cost[i-1] = (unsigned long long)ints[i]*1000;
5572 printk("migration_cost[%d]: %Ld\n", i-1, migration_cost[i-1]);
5573 }
5574 return 1;
5575}
5576
5577__setup ("migration_cost=", migration_cost_setup);
5578
5579/*
5580 * Global multiplier (divisor) for migration-cutoff values,
5581 * in percentiles. E.g. use a value of 150 to get 1.5 times
5582 * longer cache-hot cutoff times.
5583 *
5584 * (We scale it from 100 to 128 to long long handling easier.)
5585 */
5586
5587#define MIGRATION_FACTOR_SCALE 128
5588
5589static unsigned int migration_factor = MIGRATION_FACTOR_SCALE;
5590
5591static int __init setup_migration_factor(char *str)
5592{
5593 get_option(&str, &migration_factor);
5594 migration_factor = migration_factor * MIGRATION_FACTOR_SCALE / 100;
5595 return 1;
5596}
5597
5598__setup("migration_factor=", setup_migration_factor);
5599
5600/*
5601 * Estimated distance of two CPUs, measured via the number of domains
5602 * we have to pass for the two CPUs to be in the same span:
5603 */
5604static unsigned long domain_distance(int cpu1, int cpu2)
5605{
5606 unsigned long distance = 0;
5607 struct sched_domain *sd;
5608
5609 for_each_domain(cpu1, sd) {
5610 WARN_ON(!cpu_isset(cpu1, sd->span));
5611 if (cpu_isset(cpu2, sd->span))
5612 return distance;
5613 distance++;
5614 }
5615 if (distance >= MAX_DOMAIN_DISTANCE) {
5616 WARN_ON(1);
5617 distance = MAX_DOMAIN_DISTANCE-1;
5618 }
5619
5620 return distance;
5621}
5622
5623static unsigned int migration_debug;
5624
5625static int __init setup_migration_debug(char *str)
5626{
5627 get_option(&str, &migration_debug);
5628 return 1;
5629}
5630
5631__setup("migration_debug=", setup_migration_debug);
5632
5633/*
5634 * Maximum cache-size that the scheduler should try to measure.
5635 * Architectures with larger caches should tune this up during
5636 * bootup. Gets used in the domain-setup code (i.e. during SMP
5637 * bootup).
5638 */
5639unsigned int max_cache_size;
5640
5641static int __init setup_max_cache_size(char *str)
5642{
5643 get_option(&str, &max_cache_size);
5644 return 1;
5645}
5646
5647__setup("max_cache_size=", setup_max_cache_size);
5648
5649/*
5650 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5651 * is the operation that is timed, so we try to generate unpredictable
5652 * cachemisses that still end up filling the L2 cache:
5653 */
5654static void touch_cache(void *__cache, unsigned long __size)
5655{
33859f7f
MOS
5656 unsigned long size = __size / sizeof(long);
5657 unsigned long chunk1 = size / 3;
5658 unsigned long chunk2 = 2 * size / 3;
198e2f18 5659 unsigned long *cache = __cache;
5660 int i;
5661
5662 for (i = 0; i < size/6; i += 8) {
5663 switch (i % 6) {
5664 case 0: cache[i]++;
5665 case 1: cache[size-1-i]++;
5666 case 2: cache[chunk1-i]++;
5667 case 3: cache[chunk1+i]++;
5668 case 4: cache[chunk2-i]++;
5669 case 5: cache[chunk2+i]++;
5670 }
5671 }
5672}
5673
5674/*
5675 * Measure the cache-cost of one task migration. Returns in units of nsec.
5676 */
48f24c4d
IM
5677static unsigned long long
5678measure_one(void *cache, unsigned long size, int source, int target)
198e2f18 5679{
5680 cpumask_t mask, saved_mask;
5681 unsigned long long t0, t1, t2, t3, cost;
5682
5683 saved_mask = current->cpus_allowed;
5684
5685 /*
5686 * Flush source caches to RAM and invalidate them:
5687 */
5688 sched_cacheflush();
5689
5690 /*
5691 * Migrate to the source CPU:
5692 */
5693 mask = cpumask_of_cpu(source);
5694 set_cpus_allowed(current, mask);
5695 WARN_ON(smp_processor_id() != source);
5696
5697 /*
5698 * Dirty the working set:
5699 */
5700 t0 = sched_clock();
5701 touch_cache(cache, size);
5702 t1 = sched_clock();
5703
5704 /*
5705 * Migrate to the target CPU, dirty the L2 cache and access
5706 * the shared buffer. (which represents the working set
5707 * of a migrated task.)
5708 */
5709 mask = cpumask_of_cpu(target);
5710 set_cpus_allowed(current, mask);
5711 WARN_ON(smp_processor_id() != target);
5712
5713 t2 = sched_clock();
5714 touch_cache(cache, size);
5715 t3 = sched_clock();
5716
5717 cost = t1-t0 + t3-t2;
5718
5719 if (migration_debug >= 2)
5720 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5721 source, target, t1-t0, t1-t0, t3-t2, cost);
5722 /*
5723 * Flush target caches to RAM and invalidate them:
5724 */
5725 sched_cacheflush();
5726
5727 set_cpus_allowed(current, saved_mask);
5728
5729 return cost;
5730}
5731
5732/*
5733 * Measure a series of task migrations and return the average
5734 * result. Since this code runs early during bootup the system
5735 * is 'undisturbed' and the average latency makes sense.
5736 *
5737 * The algorithm in essence auto-detects the relevant cache-size,
5738 * so it will properly detect different cachesizes for different
5739 * cache-hierarchies, depending on how the CPUs are connected.
5740 *
5741 * Architectures can prime the upper limit of the search range via
5742 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5743 */
5744static unsigned long long
5745measure_cost(int cpu1, int cpu2, void *cache, unsigned int size)
5746{
5747 unsigned long long cost1, cost2;
5748 int i;
5749
5750 /*
5751 * Measure the migration cost of 'size' bytes, over an
5752 * average of 10 runs:
5753 *
5754 * (We perturb the cache size by a small (0..4k)
5755 * value to compensate size/alignment related artifacts.
5756 * We also subtract the cost of the operation done on
5757 * the same CPU.)
5758 */
5759 cost1 = 0;
5760
5761 /*
5762 * dry run, to make sure we start off cache-cold on cpu1,
5763 * and to get any vmalloc pagefaults in advance:
5764 */
5765 measure_one(cache, size, cpu1, cpu2);
5766 for (i = 0; i < ITERATIONS; i++)
33859f7f 5767 cost1 += measure_one(cache, size - i * 1024, cpu1, cpu2);
198e2f18 5768
5769 measure_one(cache, size, cpu2, cpu1);
5770 for (i = 0; i < ITERATIONS; i++)
33859f7f 5771 cost1 += measure_one(cache, size - i * 1024, cpu2, cpu1);
198e2f18 5772
5773 /*
5774 * (We measure the non-migrating [cached] cost on both
5775 * cpu1 and cpu2, to handle CPUs with different speeds)
5776 */
5777 cost2 = 0;
5778
5779 measure_one(cache, size, cpu1, cpu1);
5780 for (i = 0; i < ITERATIONS; i++)
33859f7f 5781 cost2 += measure_one(cache, size - i * 1024, cpu1, cpu1);
198e2f18 5782
5783 measure_one(cache, size, cpu2, cpu2);
5784 for (i = 0; i < ITERATIONS; i++)
33859f7f 5785 cost2 += measure_one(cache, size - i * 1024, cpu2, cpu2);
198e2f18 5786
5787 /*
5788 * Get the per-iteration migration cost:
5789 */
33859f7f
MOS
5790 do_div(cost1, 2 * ITERATIONS);
5791 do_div(cost2, 2 * ITERATIONS);
198e2f18 5792
5793 return cost1 - cost2;
5794}
5795
5796static unsigned long long measure_migration_cost(int cpu1, int cpu2)
5797{
5798 unsigned long long max_cost = 0, fluct = 0, avg_fluct = 0;
5799 unsigned int max_size, size, size_found = 0;
5800 long long cost = 0, prev_cost;
5801 void *cache;
5802
5803 /*
5804 * Search from max_cache_size*5 down to 64K - the real relevant
5805 * cachesize has to lie somewhere inbetween.
5806 */
5807 if (max_cache_size) {
5808 max_size = max(max_cache_size * SEARCH_SCOPE, MIN_CACHE_SIZE);
5809 size = max(max_cache_size / SEARCH_SCOPE, MIN_CACHE_SIZE);
5810 } else {
5811 /*
5812 * Since we have no estimation about the relevant
5813 * search range
5814 */
5815 max_size = DEFAULT_CACHE_SIZE * SEARCH_SCOPE;
5816 size = MIN_CACHE_SIZE;
5817 }
5818
5819 if (!cpu_online(cpu1) || !cpu_online(cpu2)) {
5820 printk("cpu %d and %d not both online!\n", cpu1, cpu2);
5821 return 0;
5822 }
5823
5824 /*
5825 * Allocate the working set:
5826 */
5827 cache = vmalloc(max_size);
5828 if (!cache) {
33859f7f 5829 printk("could not vmalloc %d bytes for cache!\n", 2 * max_size);
2ed6e34f 5830 return 1000000; /* return 1 msec on very small boxen */
198e2f18 5831 }
5832
5833 while (size <= max_size) {
5834 prev_cost = cost;
5835 cost = measure_cost(cpu1, cpu2, cache, size);
5836
5837 /*
5838 * Update the max:
5839 */
5840 if (cost > 0) {
5841 if (max_cost < cost) {
5842 max_cost = cost;
5843 size_found = size;
5844 }
5845 }
5846 /*
5847 * Calculate average fluctuation, we use this to prevent
5848 * noise from triggering an early break out of the loop:
5849 */
5850 fluct = abs(cost - prev_cost);
5851 avg_fluct = (avg_fluct + fluct)/2;
5852
5853 if (migration_debug)
33859f7f
MOS
5854 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): "
5855 "(%8Ld %8Ld)\n",
198e2f18 5856 cpu1, cpu2, size,
5857 (long)cost / 1000000,
5858 ((long)cost / 100000) % 10,
5859 (long)max_cost / 1000000,
5860 ((long)max_cost / 100000) % 10,
5861 domain_distance(cpu1, cpu2),
5862 cost, avg_fluct);
5863
5864 /*
5865 * If we iterated at least 20% past the previous maximum,
5866 * and the cost has dropped by more than 20% already,
5867 * (taking fluctuations into account) then we assume to
5868 * have found the maximum and break out of the loop early:
5869 */
5870 if (size_found && (size*100 > size_found*SIZE_THRESH))
5871 if (cost+avg_fluct <= 0 ||
5872 max_cost*100 > (cost+avg_fluct)*COST_THRESH) {
5873
5874 if (migration_debug)
5875 printk("-> found max.\n");
5876 break;
5877 }
5878 /*
70b4d63e 5879 * Increase the cachesize in 10% steps:
198e2f18 5880 */
70b4d63e 5881 size = size * 10 / 9;
198e2f18 5882 }
5883
5884 if (migration_debug)
5885 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
5886 cpu1, cpu2, size_found, max_cost);
5887
5888 vfree(cache);
5889
5890 /*
5891 * A task is considered 'cache cold' if at least 2 times
5892 * the worst-case cost of migration has passed.
5893 *
5894 * (this limit is only listened to if the load-balancing
5895 * situation is 'nice' - if there is a large imbalance we
5896 * ignore it for the sake of CPU utilization and
5897 * processing fairness.)
5898 */
5899 return 2 * max_cost * migration_factor / MIGRATION_FACTOR_SCALE;
5900}
5901
5902static void calibrate_migration_costs(const cpumask_t *cpu_map)
5903{
5904 int cpu1 = -1, cpu2 = -1, cpu, orig_cpu = raw_smp_processor_id();
5905 unsigned long j0, j1, distance, max_distance = 0;
5906 struct sched_domain *sd;
5907
5908 j0 = jiffies;
5909
5910 /*
5911 * First pass - calculate the cacheflush times:
5912 */
5913 for_each_cpu_mask(cpu1, *cpu_map) {
5914 for_each_cpu_mask(cpu2, *cpu_map) {
5915 if (cpu1 == cpu2)
5916 continue;
5917 distance = domain_distance(cpu1, cpu2);
5918 max_distance = max(max_distance, distance);
5919 /*
5920 * No result cached yet?
5921 */
5922 if (migration_cost[distance] == -1LL)
5923 migration_cost[distance] =
5924 measure_migration_cost(cpu1, cpu2);
5925 }
5926 }
5927 /*
5928 * Second pass - update the sched domain hierarchy with
5929 * the new cache-hot-time estimations:
5930 */
5931 for_each_cpu_mask(cpu, *cpu_map) {
5932 distance = 0;
5933 for_each_domain(cpu, sd) {
5934 sd->cache_hot_time = migration_cost[distance];
5935 distance++;
5936 }
5937 }
5938 /*
5939 * Print the matrix:
5940 */
5941 if (migration_debug)
5942 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
5943 max_cache_size,
5944#ifdef CONFIG_X86
5945 cpu_khz/1000
5946#else
5947 -1
5948#endif
5949 );
33859f7f
MOS
5950 if (system_state == SYSTEM_BOOTING && num_online_cpus() > 1) {
5951 printk("migration_cost=");
5952 for (distance = 0; distance <= max_distance; distance++) {
5953 if (distance)
5954 printk(",");
5955 printk("%ld", (long)migration_cost[distance] / 1000);
bd576c95 5956 }
33859f7f 5957 printk("\n");
198e2f18 5958 }
198e2f18 5959 j1 = jiffies;
5960 if (migration_debug)
33859f7f 5961 printk("migration: %ld seconds\n", (j1-j0) / HZ);
198e2f18 5962
5963 /*
5964 * Move back to the original CPU. NUMA-Q gets confused
5965 * if we migrate to another quad during bootup.
5966 */
5967 if (raw_smp_processor_id() != orig_cpu) {
5968 cpumask_t mask = cpumask_of_cpu(orig_cpu),
5969 saved_mask = current->cpus_allowed;
5970
5971 set_cpus_allowed(current, mask);
5972 set_cpus_allowed(current, saved_mask);
5973 }
5974}
5975
9c1cfda2 5976#ifdef CONFIG_NUMA
198e2f18 5977
9c1cfda2
JH
5978/**
5979 * find_next_best_node - find the next node to include in a sched_domain
5980 * @node: node whose sched_domain we're building
5981 * @used_nodes: nodes already in the sched_domain
5982 *
5983 * Find the next node to include in a given scheduling domain. Simply
5984 * finds the closest node not already in the @used_nodes map.
5985 *
5986 * Should use nodemask_t.
5987 */
5988static int find_next_best_node(int node, unsigned long *used_nodes)
5989{
5990 int i, n, val, min_val, best_node = 0;
5991
5992 min_val = INT_MAX;
5993
5994 for (i = 0; i < MAX_NUMNODES; i++) {
5995 /* Start at @node */
5996 n = (node + i) % MAX_NUMNODES;
5997
5998 if (!nr_cpus_node(n))
5999 continue;
6000
6001 /* Skip already used nodes */
6002 if (test_bit(n, used_nodes))
6003 continue;
6004
6005 /* Simple min distance search */
6006 val = node_distance(node, n);
6007
6008 if (val < min_val) {
6009 min_val = val;
6010 best_node = n;
6011 }
6012 }
6013
6014 set_bit(best_node, used_nodes);
6015 return best_node;
6016}
6017
6018/**
6019 * sched_domain_node_span - get a cpumask for a node's sched_domain
6020 * @node: node whose cpumask we're constructing
6021 * @size: number of nodes to include in this span
6022 *
6023 * Given a node, construct a good cpumask for its sched_domain to span. It
6024 * should be one that prevents unnecessary balancing, but also spreads tasks
6025 * out optimally.
6026 */
6027static cpumask_t sched_domain_node_span(int node)
6028{
9c1cfda2 6029 DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
48f24c4d
IM
6030 cpumask_t span, nodemask;
6031 int i;
9c1cfda2
JH
6032
6033 cpus_clear(span);
6034 bitmap_zero(used_nodes, MAX_NUMNODES);
6035
6036 nodemask = node_to_cpumask(node);
6037 cpus_or(span, span, nodemask);
6038 set_bit(node, used_nodes);
6039
6040 for (i = 1; i < SD_NODES_PER_DOMAIN; i++) {
6041 int next_node = find_next_best_node(node, used_nodes);
48f24c4d 6042
9c1cfda2
JH
6043 nodemask = node_to_cpumask(next_node);
6044 cpus_or(span, span, nodemask);
6045 }
6046
6047 return span;
6048}
6049#endif
6050
5c45bf27 6051int sched_smt_power_savings = 0, sched_mc_power_savings = 0;
48f24c4d 6052
9c1cfda2 6053/*
48f24c4d 6054 * SMT sched-domains:
9c1cfda2 6055 */
1da177e4
LT
6056#ifdef CONFIG_SCHED_SMT
6057static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
6711cab4 6058static DEFINE_PER_CPU(struct sched_group, sched_group_cpus);
48f24c4d 6059
6711cab4
SS
6060static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map,
6061 struct sched_group **sg)
1da177e4 6062{
6711cab4
SS
6063 if (sg)
6064 *sg = &per_cpu(sched_group_cpus, cpu);
1da177e4
LT
6065 return cpu;
6066}
6067#endif
6068
48f24c4d
IM
6069/*
6070 * multi-core sched-domains:
6071 */
1e9f28fa
SS
6072#ifdef CONFIG_SCHED_MC
6073static DEFINE_PER_CPU(struct sched_domain, core_domains);
6711cab4 6074static DEFINE_PER_CPU(struct sched_group, sched_group_core);
1e9f28fa
SS
6075#endif
6076
6077#if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6711cab4
SS
6078static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
6079 struct sched_group **sg)
1e9f28fa 6080{
6711cab4 6081 int group;
a616058b
SS
6082 cpumask_t mask = cpu_sibling_map[cpu];
6083 cpus_and(mask, mask, *cpu_map);
6711cab4
SS
6084 group = first_cpu(mask);
6085 if (sg)
6086 *sg = &per_cpu(sched_group_core, group);
6087 return group;
1e9f28fa
SS
6088}
6089#elif defined(CONFIG_SCHED_MC)
6711cab4
SS
6090static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map,
6091 struct sched_group **sg)
1e9f28fa 6092{
6711cab4
SS
6093 if (sg)
6094 *sg = &per_cpu(sched_group_core, cpu);
1e9f28fa
SS
6095 return cpu;
6096}
6097#endif
6098
1da177e4 6099static DEFINE_PER_CPU(struct sched_domain, phys_domains);
6711cab4 6100static DEFINE_PER_CPU(struct sched_group, sched_group_phys);
48f24c4d 6101
6711cab4
SS
6102static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map,
6103 struct sched_group **sg)
1da177e4 6104{
6711cab4 6105 int group;
48f24c4d 6106#ifdef CONFIG_SCHED_MC
1e9f28fa 6107 cpumask_t mask = cpu_coregroup_map(cpu);
a616058b 6108 cpus_and(mask, mask, *cpu_map);
6711cab4 6109 group = first_cpu(mask);
1e9f28fa 6110#elif defined(CONFIG_SCHED_SMT)
a616058b
SS
6111 cpumask_t mask = cpu_sibling_map[cpu];
6112 cpus_and(mask, mask, *cpu_map);
6711cab4 6113 group = first_cpu(mask);
1da177e4 6114#else
6711cab4 6115 group = cpu;
1da177e4 6116#endif
6711cab4
SS
6117 if (sg)
6118 *sg = &per_cpu(sched_group_phys, group);
6119 return group;
1da177e4
LT
6120}
6121
6122#ifdef CONFIG_NUMA
1da177e4 6123/*
9c1cfda2
JH
6124 * The init_sched_build_groups can't handle what we want to do with node
6125 * groups, so roll our own. Now each node has its own list of groups which
6126 * gets dynamically allocated.
1da177e4 6127 */
9c1cfda2 6128static DEFINE_PER_CPU(struct sched_domain, node_domains);
d1b55138 6129static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
1da177e4 6130
9c1cfda2 6131static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
6711cab4 6132static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes);
9c1cfda2 6133
6711cab4
SS
6134static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map,
6135 struct sched_group **sg)
9c1cfda2 6136{
6711cab4
SS
6137 cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu));
6138 int group;
6139
6140 cpus_and(nodemask, nodemask, *cpu_map);
6141 group = first_cpu(nodemask);
6142
6143 if (sg)
6144 *sg = &per_cpu(sched_group_allnodes, group);
6145 return group;
1da177e4 6146}
6711cab4 6147
08069033
SS
6148static void init_numa_sched_groups_power(struct sched_group *group_head)
6149{
6150 struct sched_group *sg = group_head;
6151 int j;
6152
6153 if (!sg)
6154 return;
6155next_sg:
6156 for_each_cpu_mask(j, sg->cpumask) {
6157 struct sched_domain *sd;
6158
6159 sd = &per_cpu(phys_domains, j);
6160 if (j != first_cpu(sd->groups->cpumask)) {
6161 /*
6162 * Only add "power" once for each
6163 * physical package.
6164 */
6165 continue;
6166 }
6167
6168 sg->cpu_power += sd->groups->cpu_power;
6169 }
6170 sg = sg->next;
6171 if (sg != group_head)
6172 goto next_sg;
6173}
1da177e4
LT
6174#endif
6175
a616058b 6176#ifdef CONFIG_NUMA
51888ca2
SV
6177/* Free memory allocated for various sched_group structures */
6178static void free_sched_groups(const cpumask_t *cpu_map)
6179{
a616058b 6180 int cpu, i;
51888ca2
SV
6181
6182 for_each_cpu_mask(cpu, *cpu_map) {
51888ca2
SV
6183 struct sched_group **sched_group_nodes
6184 = sched_group_nodes_bycpu[cpu];
6185
51888ca2
SV
6186 if (!sched_group_nodes)
6187 continue;
6188
6189 for (i = 0; i < MAX_NUMNODES; i++) {
6190 cpumask_t nodemask = node_to_cpumask(i);
6191 struct sched_group *oldsg, *sg = sched_group_nodes[i];
6192
6193 cpus_and(nodemask, nodemask, *cpu_map);
6194 if (cpus_empty(nodemask))
6195 continue;
6196
6197 if (sg == NULL)
6198 continue;
6199 sg = sg->next;
6200next_sg:
6201 oldsg = sg;
6202 sg = sg->next;
6203 kfree(oldsg);
6204 if (oldsg != sched_group_nodes[i])
6205 goto next_sg;
6206 }
6207 kfree(sched_group_nodes);
6208 sched_group_nodes_bycpu[cpu] = NULL;
6209 }
51888ca2 6210}
a616058b
SS
6211#else
6212static void free_sched_groups(const cpumask_t *cpu_map)
6213{
6214}
6215#endif
51888ca2 6216
89c4710e
SS
6217/*
6218 * Initialize sched groups cpu_power.
6219 *
6220 * cpu_power indicates the capacity of sched group, which is used while
6221 * distributing the load between different sched groups in a sched domain.
6222 * Typically cpu_power for all the groups in a sched domain will be same unless
6223 * there are asymmetries in the topology. If there are asymmetries, group
6224 * having more cpu_power will pickup more load compared to the group having
6225 * less cpu_power.
6226 *
6227 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6228 * the maximum number of tasks a group can handle in the presence of other idle
6229 * or lightly loaded groups in the same sched domain.
6230 */
6231static void init_sched_groups_power(int cpu, struct sched_domain *sd)
6232{
6233 struct sched_domain *child;
6234 struct sched_group *group;
6235
6236 WARN_ON(!sd || !sd->groups);
6237
6238 if (cpu != first_cpu(sd->groups->cpumask))
6239 return;
6240
6241 child = sd->child;
6242
6243 /*
6244 * For perf policy, if the groups in child domain share resources
6245 * (for example cores sharing some portions of the cache hierarchy
6246 * or SMT), then set this domain groups cpu_power such that each group
6247 * can handle only one task, when there are other idle groups in the
6248 * same sched domain.
6249 */
6250 if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) &&
6251 (child->flags &
6252 (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) {
6253 sd->groups->cpu_power = SCHED_LOAD_SCALE;
6254 return;
6255 }
6256
6257 sd->groups->cpu_power = 0;
6258
6259 /*
6260 * add cpu_power of each child group to this groups cpu_power
6261 */
6262 group = child->groups;
6263 do {
6264 sd->groups->cpu_power += group->cpu_power;
6265 group = group->next;
6266 } while (group != child->groups);
6267}
6268
1da177e4 6269/*
1a20ff27
DG
6270 * Build sched domains for a given set of cpus and attach the sched domains
6271 * to the individual cpus
1da177e4 6272 */
51888ca2 6273static int build_sched_domains(const cpumask_t *cpu_map)
1da177e4
LT
6274{
6275 int i;
89c4710e 6276 struct sched_domain *sd;
d1b55138
JH
6277#ifdef CONFIG_NUMA
6278 struct sched_group **sched_group_nodes = NULL;
6711cab4 6279 int sd_allnodes = 0;
d1b55138
JH
6280
6281 /*
6282 * Allocate the per-node list of sched groups
6283 */
51888ca2 6284 sched_group_nodes = kzalloc(sizeof(struct sched_group*)*MAX_NUMNODES,
d3a5aa98 6285 GFP_KERNEL);
d1b55138
JH
6286 if (!sched_group_nodes) {
6287 printk(KERN_WARNING "Can not alloc sched group node list\n");
51888ca2 6288 return -ENOMEM;
d1b55138
JH
6289 }
6290 sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
6291#endif
1da177e4
LT
6292
6293 /*
1a20ff27 6294 * Set up domains for cpus specified by the cpu_map.
1da177e4 6295 */
1a20ff27 6296 for_each_cpu_mask(i, *cpu_map) {
1da177e4
LT
6297 struct sched_domain *sd = NULL, *p;
6298 cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
6299
1a20ff27 6300 cpus_and(nodemask, nodemask, *cpu_map);
1da177e4
LT
6301
6302#ifdef CONFIG_NUMA
d1b55138 6303 if (cpus_weight(*cpu_map)
9c1cfda2
JH
6304 > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
6305 sd = &per_cpu(allnodes_domains, i);
6306 *sd = SD_ALLNODES_INIT;
6307 sd->span = *cpu_map;
6711cab4 6308 cpu_to_allnodes_group(i, cpu_map, &sd->groups);
9c1cfda2 6309 p = sd;
6711cab4 6310 sd_allnodes = 1;
9c1cfda2
JH
6311 } else
6312 p = NULL;
6313
1da177e4 6314 sd = &per_cpu(node_domains, i);
1da177e4 6315 *sd = SD_NODE_INIT;
9c1cfda2
JH
6316 sd->span = sched_domain_node_span(cpu_to_node(i));
6317 sd->parent = p;
1a848870
SS
6318 if (p)
6319 p->child = sd;
9c1cfda2 6320 cpus_and(sd->span, sd->span, *cpu_map);
1da177e4
LT
6321#endif
6322
6323 p = sd;
6324 sd = &per_cpu(phys_domains, i);
1da177e4
LT
6325 *sd = SD_CPU_INIT;
6326 sd->span = nodemask;
6327 sd->parent = p;
1a848870
SS
6328 if (p)
6329 p->child = sd;
6711cab4 6330 cpu_to_phys_group(i, cpu_map, &sd->groups);
1da177e4 6331
1e9f28fa
SS
6332#ifdef CONFIG_SCHED_MC
6333 p = sd;
6334 sd = &per_cpu(core_domains, i);
1e9f28fa
SS
6335 *sd = SD_MC_INIT;
6336 sd->span = cpu_coregroup_map(i);
6337 cpus_and(sd->span, sd->span, *cpu_map);
6338 sd->parent = p;
1a848870 6339 p->child = sd;
6711cab4 6340 cpu_to_core_group(i, cpu_map, &sd->groups);
1e9f28fa
SS
6341#endif
6342
1da177e4
LT
6343#ifdef CONFIG_SCHED_SMT
6344 p = sd;
6345 sd = &per_cpu(cpu_domains, i);
1da177e4
LT
6346 *sd = SD_SIBLING_INIT;
6347 sd->span = cpu_sibling_map[i];
1a20ff27 6348 cpus_and(sd->span, sd->span, *cpu_map);
1da177e4 6349 sd->parent = p;
1a848870 6350 p->child = sd;
6711cab4 6351 cpu_to_cpu_group(i, cpu_map, &sd->groups);
1da177e4
LT
6352#endif
6353 }
6354
6355#ifdef CONFIG_SCHED_SMT
6356 /* Set up CPU (sibling) groups */
9c1cfda2 6357 for_each_cpu_mask(i, *cpu_map) {
1da177e4 6358 cpumask_t this_sibling_map = cpu_sibling_map[i];
1a20ff27 6359 cpus_and(this_sibling_map, this_sibling_map, *cpu_map);
1da177e4
LT
6360 if (i != first_cpu(this_sibling_map))
6361 continue;
6362
6711cab4 6363 init_sched_build_groups(this_sibling_map, cpu_map, &cpu_to_cpu_group);
1da177e4
LT
6364 }
6365#endif
6366
1e9f28fa
SS
6367#ifdef CONFIG_SCHED_MC
6368 /* Set up multi-core groups */
6369 for_each_cpu_mask(i, *cpu_map) {
6370 cpumask_t this_core_map = cpu_coregroup_map(i);
6371 cpus_and(this_core_map, this_core_map, *cpu_map);
6372 if (i != first_cpu(this_core_map))
6373 continue;
6711cab4 6374 init_sched_build_groups(this_core_map, cpu_map, &cpu_to_core_group);
1e9f28fa
SS
6375 }
6376#endif
6377
6378
1da177e4
LT
6379 /* Set up physical groups */
6380 for (i = 0; i < MAX_NUMNODES; i++) {
6381 cpumask_t nodemask = node_to_cpumask(i);
6382
1a20ff27 6383 cpus_and(nodemask, nodemask, *cpu_map);
1da177e4
LT
6384 if (cpus_empty(nodemask))
6385 continue;
6386
6711cab4 6387 init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group);
1da177e4
LT
6388 }
6389
6390#ifdef CONFIG_NUMA
6391 /* Set up node groups */
6711cab4
SS
6392 if (sd_allnodes)
6393 init_sched_build_groups(*cpu_map, cpu_map, &cpu_to_allnodes_group);
9c1cfda2
JH
6394
6395 for (i = 0; i < MAX_NUMNODES; i++) {
6396 /* Set up node groups */
6397 struct sched_group *sg, *prev;
6398 cpumask_t nodemask = node_to_cpumask(i);
6399 cpumask_t domainspan;
6400 cpumask_t covered = CPU_MASK_NONE;
6401 int j;
6402
6403 cpus_and(nodemask, nodemask, *cpu_map);
d1b55138
JH
6404 if (cpus_empty(nodemask)) {
6405 sched_group_nodes[i] = NULL;
9c1cfda2 6406 continue;
d1b55138 6407 }
9c1cfda2
JH
6408
6409 domainspan = sched_domain_node_span(i);
6410 cpus_and(domainspan, domainspan, *cpu_map);
6411
15f0b676 6412 sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
51888ca2
SV
6413 if (!sg) {
6414 printk(KERN_WARNING "Can not alloc domain group for "
6415 "node %d\n", i);
6416 goto error;
6417 }
9c1cfda2
JH
6418 sched_group_nodes[i] = sg;
6419 for_each_cpu_mask(j, nodemask) {
6420 struct sched_domain *sd;
6421 sd = &per_cpu(node_domains, j);
6422 sd->groups = sg;
9c1cfda2
JH
6423 }
6424 sg->cpu_power = 0;
6425 sg->cpumask = nodemask;
51888ca2 6426 sg->next = sg;
9c1cfda2
JH
6427 cpus_or(covered, covered, nodemask);
6428 prev = sg;
6429
6430 for (j = 0; j < MAX_NUMNODES; j++) {
6431 cpumask_t tmp, notcovered;
6432 int n = (i + j) % MAX_NUMNODES;
6433
6434 cpus_complement(notcovered, covered);
6435 cpus_and(tmp, notcovered, *cpu_map);
6436 cpus_and(tmp, tmp, domainspan);
6437 if (cpus_empty(tmp))
6438 break;
6439
6440 nodemask = node_to_cpumask(n);
6441 cpus_and(tmp, tmp, nodemask);
6442 if (cpus_empty(tmp))
6443 continue;
6444
15f0b676
SV
6445 sg = kmalloc_node(sizeof(struct sched_group),
6446 GFP_KERNEL, i);
9c1cfda2
JH
6447 if (!sg) {
6448 printk(KERN_WARNING
6449 "Can not alloc domain group for node %d\n", j);
51888ca2 6450 goto error;
9c1cfda2
JH
6451 }
6452 sg->cpu_power = 0;
6453 sg->cpumask = tmp;
51888ca2 6454 sg->next = prev->next;
9c1cfda2
JH
6455 cpus_or(covered, covered, tmp);
6456 prev->next = sg;
6457 prev = sg;
6458 }
9c1cfda2 6459 }
1da177e4
LT
6460#endif
6461
6462 /* Calculate CPU power for physical packages and nodes */
5c45bf27 6463#ifdef CONFIG_SCHED_SMT
1a20ff27 6464 for_each_cpu_mask(i, *cpu_map) {
1da177e4 6465 sd = &per_cpu(cpu_domains, i);
89c4710e 6466 init_sched_groups_power(i, sd);
5c45bf27 6467 }
1da177e4 6468#endif
1e9f28fa 6469#ifdef CONFIG_SCHED_MC
5c45bf27 6470 for_each_cpu_mask(i, *cpu_map) {
1e9f28fa 6471 sd = &per_cpu(core_domains, i);
89c4710e 6472 init_sched_groups_power(i, sd);
5c45bf27
SS
6473 }
6474#endif
1e9f28fa 6475
5c45bf27 6476 for_each_cpu_mask(i, *cpu_map) {
1da177e4 6477 sd = &per_cpu(phys_domains, i);
89c4710e 6478 init_sched_groups_power(i, sd);
1da177e4
LT
6479 }
6480
9c1cfda2 6481#ifdef CONFIG_NUMA
08069033
SS
6482 for (i = 0; i < MAX_NUMNODES; i++)
6483 init_numa_sched_groups_power(sched_group_nodes[i]);
9c1cfda2 6484
6711cab4
SS
6485 if (sd_allnodes) {
6486 struct sched_group *sg;
f712c0c7 6487
6711cab4 6488 cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg);
f712c0c7
SS
6489 init_numa_sched_groups_power(sg);
6490 }
9c1cfda2
JH
6491#endif
6492
1da177e4 6493 /* Attach the domains */
1a20ff27 6494 for_each_cpu_mask(i, *cpu_map) {
1da177e4
LT
6495 struct sched_domain *sd;
6496#ifdef CONFIG_SCHED_SMT
6497 sd = &per_cpu(cpu_domains, i);
1e9f28fa
SS
6498#elif defined(CONFIG_SCHED_MC)
6499 sd = &per_cpu(core_domains, i);
1da177e4
LT
6500#else
6501 sd = &per_cpu(phys_domains, i);
6502#endif
6503 cpu_attach_domain(sd, i);
6504 }
198e2f18 6505 /*
6506 * Tune cache-hot values:
6507 */
6508 calibrate_migration_costs(cpu_map);
51888ca2
SV
6509
6510 return 0;
6511
a616058b 6512#ifdef CONFIG_NUMA
51888ca2
SV
6513error:
6514 free_sched_groups(cpu_map);
6515 return -ENOMEM;
a616058b 6516#endif
1da177e4 6517}
1a20ff27
DG
6518/*
6519 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6520 */
51888ca2 6521static int arch_init_sched_domains(const cpumask_t *cpu_map)
1a20ff27
DG
6522{
6523 cpumask_t cpu_default_map;
51888ca2 6524 int err;
1da177e4 6525
1a20ff27
DG
6526 /*
6527 * Setup mask for cpus without special case scheduling requirements.
6528 * For now this just excludes isolated cpus, but could be used to
6529 * exclude other special cases in the future.
6530 */
6531 cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map);
6532
51888ca2
SV
6533 err = build_sched_domains(&cpu_default_map);
6534
6535 return err;
1a20ff27
DG
6536}
6537
6538static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
1da177e4 6539{
51888ca2 6540 free_sched_groups(cpu_map);
9c1cfda2 6541}
1da177e4 6542
1a20ff27
DG
6543/*
6544 * Detach sched domains from a group of cpus specified in cpu_map
6545 * These cpus will now be attached to the NULL domain
6546 */
858119e1 6547static void detach_destroy_domains(const cpumask_t *cpu_map)
1a20ff27
DG
6548{
6549 int i;
6550
6551 for_each_cpu_mask(i, *cpu_map)
6552 cpu_attach_domain(NULL, i);
6553 synchronize_sched();
6554 arch_destroy_sched_domains(cpu_map);
6555}
6556
6557/*
6558 * Partition sched domains as specified by the cpumasks below.
6559 * This attaches all cpus from the cpumasks to the NULL domain,
6560 * waits for a RCU quiescent period, recalculates sched
6561 * domain information and then attaches them back to the
6562 * correct sched domains
6563 * Call with hotplug lock held
6564 */
51888ca2 6565int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2)
1a20ff27
DG
6566{
6567 cpumask_t change_map;
51888ca2 6568 int err = 0;
1a20ff27
DG
6569
6570 cpus_and(*partition1, *partition1, cpu_online_map);
6571 cpus_and(*partition2, *partition2, cpu_online_map);
6572 cpus_or(change_map, *partition1, *partition2);
6573
6574 /* Detach sched domains from all of the affected cpus */
6575 detach_destroy_domains(&change_map);
6576 if (!cpus_empty(*partition1))
51888ca2
SV
6577 err = build_sched_domains(partition1);
6578 if (!err && !cpus_empty(*partition2))
6579 err = build_sched_domains(partition2);
6580
6581 return err;
1a20ff27
DG
6582}
6583
5c45bf27
SS
6584#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6585int arch_reinit_sched_domains(void)
6586{
6587 int err;
6588
6589 lock_cpu_hotplug();
6590 detach_destroy_domains(&cpu_online_map);
6591 err = arch_init_sched_domains(&cpu_online_map);
6592 unlock_cpu_hotplug();
6593
6594 return err;
6595}
6596
6597static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt)
6598{
6599 int ret;
6600
6601 if (buf[0] != '0' && buf[0] != '1')
6602 return -EINVAL;
6603
6604 if (smt)
6605 sched_smt_power_savings = (buf[0] == '1');
6606 else
6607 sched_mc_power_savings = (buf[0] == '1');
6608
6609 ret = arch_reinit_sched_domains();
6610
6611 return ret ? ret : count;
6612}
6613
6614int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls)
6615{
6616 int err = 0;
48f24c4d 6617
5c45bf27
SS
6618#ifdef CONFIG_SCHED_SMT
6619 if (smt_capable())
6620 err = sysfs_create_file(&cls->kset.kobj,
6621 &attr_sched_smt_power_savings.attr);
6622#endif
6623#ifdef CONFIG_SCHED_MC
6624 if (!err && mc_capable())
6625 err = sysfs_create_file(&cls->kset.kobj,
6626 &attr_sched_mc_power_savings.attr);
6627#endif
6628 return err;
6629}
6630#endif
6631
6632#ifdef CONFIG_SCHED_MC
6633static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page)
6634{
6635 return sprintf(page, "%u\n", sched_mc_power_savings);
6636}
48f24c4d
IM
6637static ssize_t sched_mc_power_savings_store(struct sys_device *dev,
6638 const char *buf, size_t count)
5c45bf27
SS
6639{
6640 return sched_power_savings_store(buf, count, 0);
6641}
6642SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show,
6643 sched_mc_power_savings_store);
6644#endif
6645
6646#ifdef CONFIG_SCHED_SMT
6647static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page)
6648{
6649 return sprintf(page, "%u\n", sched_smt_power_savings);
6650}
48f24c4d
IM
6651static ssize_t sched_smt_power_savings_store(struct sys_device *dev,
6652 const char *buf, size_t count)
5c45bf27
SS
6653{
6654 return sched_power_savings_store(buf, count, 1);
6655}
6656SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show,
6657 sched_smt_power_savings_store);
6658#endif
6659
1da177e4
LT
6660/*
6661 * Force a reinitialization of the sched domains hierarchy. The domains
6662 * and groups cannot be updated in place without racing with the balancing
41c7ce9a 6663 * code, so we temporarily attach all running cpus to the NULL domain
1da177e4
LT
6664 * which will prevent rebalancing while the sched domains are recalculated.
6665 */
6666static int update_sched_domains(struct notifier_block *nfb,
6667 unsigned long action, void *hcpu)
6668{
1da177e4
LT
6669 switch (action) {
6670 case CPU_UP_PREPARE:
6671 case CPU_DOWN_PREPARE:
1a20ff27 6672 detach_destroy_domains(&cpu_online_map);
1da177e4
LT
6673 return NOTIFY_OK;
6674
6675 case CPU_UP_CANCELED:
6676 case CPU_DOWN_FAILED:
6677 case CPU_ONLINE:
6678 case CPU_DEAD:
6679 /*
6680 * Fall through and re-initialise the domains.
6681 */
6682 break;
6683 default:
6684 return NOTIFY_DONE;
6685 }
6686
6687 /* The hotplug lock is already held by cpu_up/cpu_down */
1a20ff27 6688 arch_init_sched_domains(&cpu_online_map);
1da177e4
LT
6689
6690 return NOTIFY_OK;
6691}
1da177e4
LT
6692
6693void __init sched_init_smp(void)
6694{
5c1e1767
NP
6695 cpumask_t non_isolated_cpus;
6696
1da177e4 6697 lock_cpu_hotplug();
1a20ff27 6698 arch_init_sched_domains(&cpu_online_map);
e5e5673f 6699 cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
5c1e1767
NP
6700 if (cpus_empty(non_isolated_cpus))
6701 cpu_set(smp_processor_id(), non_isolated_cpus);
1da177e4
LT
6702 unlock_cpu_hotplug();
6703 /* XXX: Theoretical race here - CPU may be hotplugged now */
6704 hotcpu_notifier(update_sched_domains, 0);
5c1e1767
NP
6705
6706 /* Move init over to a non-isolated CPU */
6707 if (set_cpus_allowed(current, non_isolated_cpus) < 0)
6708 BUG();
1da177e4
LT
6709}
6710#else
6711void __init sched_init_smp(void)
6712{
6713}
6714#endif /* CONFIG_SMP */
6715
6716int in_sched_functions(unsigned long addr)
6717{
6718 /* Linker adds these: start and end of __sched functions */
6719 extern char __sched_text_start[], __sched_text_end[];
48f24c4d 6720
1da177e4
LT
6721 return in_lock_functions(addr) ||
6722 (addr >= (unsigned long)__sched_text_start
6723 && addr < (unsigned long)__sched_text_end);
6724}
6725
6726void __init sched_init(void)
6727{
1da177e4
LT
6728 int i, j, k;
6729
0a945022 6730 for_each_possible_cpu(i) {
70b97a7f
IM
6731 struct prio_array *array;
6732 struct rq *rq;
1da177e4
LT
6733
6734 rq = cpu_rq(i);
6735 spin_lock_init(&rq->lock);
fcb99371 6736 lockdep_set_class(&rq->lock, &rq->rq_lock_key);
7897986b 6737 rq->nr_running = 0;
1da177e4
LT
6738 rq->active = rq->arrays;
6739 rq->expired = rq->arrays + 1;
6740 rq->best_expired_prio = MAX_PRIO;
6741
6742#ifdef CONFIG_SMP
41c7ce9a 6743 rq->sd = NULL;
7897986b
NP
6744 for (j = 1; j < 3; j++)
6745 rq->cpu_load[j] = 0;
1da177e4
LT
6746 rq->active_balance = 0;
6747 rq->push_cpu = 0;
0a2966b4 6748 rq->cpu = i;
1da177e4
LT
6749 rq->migration_thread = NULL;
6750 INIT_LIST_HEAD(&rq->migration_queue);
6751#endif
6752 atomic_set(&rq->nr_iowait, 0);
6753
6754 for (j = 0; j < 2; j++) {
6755 array = rq->arrays + j;
6756 for (k = 0; k < MAX_PRIO; k++) {
6757 INIT_LIST_HEAD(array->queue + k);
6758 __clear_bit(k, array->bitmap);
6759 }
6760 // delimiter for bitsearch
6761 __set_bit(MAX_PRIO, array->bitmap);
6762 }
6763 }
6764
2dd73a4f 6765 set_load_weight(&init_task);
b50f60ce 6766
c9819f45
CL
6767#ifdef CONFIG_SMP
6768 open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL);
6769#endif
6770
b50f60ce
HC
6771#ifdef CONFIG_RT_MUTEXES
6772 plist_head_init(&init_task.pi_waiters, &init_task.pi_lock);
6773#endif
6774
1da177e4
LT
6775 /*
6776 * The boot idle thread does lazy MMU switching as well:
6777 */
6778 atomic_inc(&init_mm.mm_count);
6779 enter_lazy_tlb(&init_mm, current);
6780
6781 /*
6782 * Make us the idle thread. Technically, schedule() should not be
6783 * called from this thread, however somewhere below it might be,
6784 * but because we are the idle thread, we just pick up running again
6785 * when this runqueue becomes "idle".
6786 */
6787 init_idle(current, smp_processor_id());
6788}
6789
6790#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6791void __might_sleep(char *file, int line)
6792{
48f24c4d 6793#ifdef in_atomic
1da177e4
LT
6794 static unsigned long prev_jiffy; /* ratelimiting */
6795
6796 if ((in_atomic() || irqs_disabled()) &&
6797 system_state == SYSTEM_RUNNING && !oops_in_progress) {
6798 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
6799 return;
6800 prev_jiffy = jiffies;
91368d73 6801 printk(KERN_ERR "BUG: sleeping function called from invalid"
1da177e4
LT
6802 " context at %s:%d\n", file, line);
6803 printk("in_atomic():%d, irqs_disabled():%d\n",
6804 in_atomic(), irqs_disabled());
a4c410f0 6805 debug_show_held_locks(current);
3117df04
IM
6806 if (irqs_disabled())
6807 print_irqtrace_events(current);
1da177e4
LT
6808 dump_stack();
6809 }
6810#endif
6811}
6812EXPORT_SYMBOL(__might_sleep);
6813#endif
6814
6815#ifdef CONFIG_MAGIC_SYSRQ
6816void normalize_rt_tasks(void)
6817{
70b97a7f 6818 struct prio_array *array;
1da177e4 6819 struct task_struct *p;
1da177e4 6820 unsigned long flags;
70b97a7f 6821 struct rq *rq;
1da177e4
LT
6822
6823 read_lock_irq(&tasklist_lock);
c96d145e 6824 for_each_process(p) {
1da177e4
LT
6825 if (!rt_task(p))
6826 continue;
6827
b29739f9
IM
6828 spin_lock_irqsave(&p->pi_lock, flags);
6829 rq = __task_rq_lock(p);
1da177e4
LT
6830
6831 array = p->array;
6832 if (array)
6833 deactivate_task(p, task_rq(p));
6834 __setscheduler(p, SCHED_NORMAL, 0);
6835 if (array) {
6836 __activate_task(p, task_rq(p));
6837 resched_task(rq->curr);
6838 }
6839
b29739f9
IM
6840 __task_rq_unlock(rq);
6841 spin_unlock_irqrestore(&p->pi_lock, flags);
1da177e4
LT
6842 }
6843 read_unlock_irq(&tasklist_lock);
6844}
6845
6846#endif /* CONFIG_MAGIC_SYSRQ */
1df5c10a
LT
6847
6848#ifdef CONFIG_IA64
6849/*
6850 * These functions are only useful for the IA64 MCA handling.
6851 *
6852 * They can only be called when the whole system has been
6853 * stopped - every CPU needs to be quiescent, and no scheduling
6854 * activity can take place. Using them for anything else would
6855 * be a serious bug, and as a result, they aren't even visible
6856 * under any other configuration.
6857 */
6858
6859/**
6860 * curr_task - return the current task for a given cpu.
6861 * @cpu: the processor in question.
6862 *
6863 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6864 */
36c8b586 6865struct task_struct *curr_task(int cpu)
1df5c10a
LT
6866{
6867 return cpu_curr(cpu);
6868}
6869
6870/**
6871 * set_curr_task - set the current task for a given cpu.
6872 * @cpu: the processor in question.
6873 * @p: the task pointer to set.
6874 *
6875 * Description: This function must only be used when non-maskable interrupts
6876 * are serviced on a separate stack. It allows the architecture to switch the
6877 * notion of the current task on a cpu in a non-blocking manner. This function
6878 * must be called with all CPU's synchronized, and interrupts disabled, the
6879 * and caller must save the original value of the current task (see
6880 * curr_task() above) and restore that value before reenabling interrupts and
6881 * re-starting the system.
6882 *
6883 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
6884 */
36c8b586 6885void set_curr_task(int cpu, struct task_struct *p)
1df5c10a
LT
6886{
6887 cpu_curr(cpu) = p;
6888}
6889
6890#endif