c61ee3451a04443ca04cd4007c6297f3993cdfd0
[pandora-kernel.git] / kernel / sched.c
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>
30 #include <linux/completion.h>
31 #include <linux/kernel_stat.h>
32 #include <linux/security.h>
33 #include <linux/notifier.h>
34 #include <linux/profile.h>
35 #include <linux/suspend.h>
36 #include <linux/blkdev.h>
37 #include <linux/delay.h>
38 #include <linux/smp.h>
39 #include <linux/threads.h>
40 #include <linux/timer.h>
41 #include <linux/rcupdate.h>
42 #include <linux/cpu.h>
43 #include <linux/cpuset.h>
44 #include <linux/percpu.h>
45 #include <linux/kthread.h>
46 #include <linux/seq_file.h>
47 #include <linux/syscalls.h>
48 #include <linux/times.h>
49 #include <linux/acct.h>
50 #include <asm/tlb.h>
51
52 #include <asm/unistd.h>
53
54 /*
55  * Convert user-nice values [ -20 ... 0 ... 19 ]
56  * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
57  * and back.
58  */
59 #define NICE_TO_PRIO(nice)      (MAX_RT_PRIO + (nice) + 20)
60 #define PRIO_TO_NICE(prio)      ((prio) - MAX_RT_PRIO - 20)
61 #define TASK_NICE(p)            PRIO_TO_NICE((p)->static_prio)
62
63 /*
64  * 'User priority' is the nice value converted to something we
65  * can work with better when scaling various scheduler parameters,
66  * it's a [ 0 ... 39 ] range.
67  */
68 #define USER_PRIO(p)            ((p)-MAX_RT_PRIO)
69 #define TASK_USER_PRIO(p)       USER_PRIO((p)->static_prio)
70 #define MAX_USER_PRIO           (USER_PRIO(MAX_PRIO))
71
72 /*
73  * Some helpers for converting nanosecond timing to jiffy resolution
74  */
75 #define NS_TO_JIFFIES(TIME)     ((TIME) / (1000000000 / HZ))
76 #define JIFFIES_TO_NS(TIME)     ((TIME) * (1000000000 / HZ))
77
78 /*
79  * These are the 'tuning knobs' of the scheduler:
80  *
81  * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
82  * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
83  * Timeslices get refilled after they expire.
84  */
85 #define MIN_TIMESLICE           max(5 * HZ / 1000, 1)
86 #define DEF_TIMESLICE           (100 * HZ / 1000)
87 #define ON_RUNQUEUE_WEIGHT       30
88 #define CHILD_PENALTY            95
89 #define PARENT_PENALTY          100
90 #define EXIT_WEIGHT               3
91 #define PRIO_BONUS_RATIO         25
92 #define MAX_BONUS               (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
93 #define INTERACTIVE_DELTA         2
94 #define MAX_SLEEP_AVG           (DEF_TIMESLICE * MAX_BONUS)
95 #define STARVATION_LIMIT        (MAX_SLEEP_AVG)
96 #define NS_MAX_SLEEP_AVG        (JIFFIES_TO_NS(MAX_SLEEP_AVG))
97
98 /*
99  * If a task is 'interactive' then we reinsert it in the active
100  * array after it has expired its current timeslice. (it will not
101  * continue to run immediately, it will still roundrobin with
102  * other interactive tasks.)
103  *
104  * This part scales the interactivity limit depending on niceness.
105  *
106  * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
107  * Here are a few examples of different nice levels:
108  *
109  *  TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
110  *  TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
111  *  TASK_INTERACTIVE(  0): [1,1,1,1,0,0,0,0,0,0,0]
112  *  TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
113  *  TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
114  *
115  * (the X axis represents the possible -5 ... 0 ... +5 dynamic
116  *  priority range a task can explore, a value of '1' means the
117  *  task is rated interactive.)
118  *
119  * Ie. nice +19 tasks can never get 'interactive' enough to be
120  * reinserted into the active array. And only heavily CPU-hog nice -20
121  * tasks will be expired. Default nice 0 tasks are somewhere between,
122  * it takes some effort for them to get interactive, but it's not
123  * too hard.
124  */
125
126 #define CURRENT_BONUS(p) \
127         (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
128                 MAX_SLEEP_AVG)
129
130 #define GRANULARITY     (10 * HZ / 1000 ? : 1)
131
132 #ifdef CONFIG_SMP
133 #define TIMESLICE_GRANULARITY(p)        (GRANULARITY * \
134                 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
135                         num_online_cpus())
136 #else
137 #define TIMESLICE_GRANULARITY(p)        (GRANULARITY * \
138                 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
139 #endif
140
141 #define SCALE(v1,v1_max,v2_max) \
142         (v1) * (v2_max) / (v1_max)
143
144 #define DELTA(p) \
145         (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
146
147 #define TASK_INTERACTIVE(p) \
148         ((p)->prio <= (p)->static_prio - DELTA(p))
149
150 #define INTERACTIVE_SLEEP(p) \
151         (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
152                 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
153
154 #define TASK_PREEMPTS_CURR(p, rq) \
155         ((p)->prio < (rq)->curr->prio)
156
157 /*
158  * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
159  * to time slice values: [800ms ... 100ms ... 5ms]
160  *
161  * The higher a thread's priority, the bigger timeslices
162  * it gets during one round of execution. But even the lowest
163  * priority thread gets MIN_TIMESLICE worth of execution time.
164  */
165
166 #define SCALE_PRIO(x, prio) \
167         max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE)
168
169 static unsigned int task_timeslice(task_t *p)
170 {
171         if (p->static_prio < NICE_TO_PRIO(0))
172                 return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio);
173         else
174                 return SCALE_PRIO(DEF_TIMESLICE, p->static_prio);
175 }
176 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran)       \
177                                 < (long long) (sd)->cache_hot_time)
178
179 /*
180  * These are the runqueue data structures:
181  */
182
183 #define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long))
184
185 typedef struct runqueue runqueue_t;
186
187 struct prio_array {
188         unsigned int nr_active;
189         unsigned long bitmap[BITMAP_SIZE];
190         struct list_head queue[MAX_PRIO];
191 };
192
193 /*
194  * This is the main, per-CPU runqueue data structure.
195  *
196  * Locking rule: those places that want to lock multiple runqueues
197  * (such as the load balancing or the thread migration code), lock
198  * acquire operations must be ordered by ascending &runqueue.
199  */
200 struct runqueue {
201         spinlock_t lock;
202
203         /*
204          * nr_running and cpu_load should be in the same cacheline because
205          * remote CPUs use both these fields when doing load calculation.
206          */
207         unsigned long nr_running;
208 #ifdef CONFIG_SMP
209         unsigned long cpu_load[3];
210 #endif
211         unsigned long long nr_switches;
212
213         /*
214          * This is part of a global counter where only the total sum
215          * over all CPUs matters. A task can increase this counter on
216          * one CPU and if it got migrated afterwards it may decrease
217          * it on another CPU. Always updated under the runqueue lock:
218          */
219         unsigned long nr_uninterruptible;
220
221         unsigned long expired_timestamp;
222         unsigned long long timestamp_last_tick;
223         task_t *curr, *idle;
224         struct mm_struct *prev_mm;
225         prio_array_t *active, *expired, arrays[2];
226         int best_expired_prio;
227         atomic_t nr_iowait;
228
229 #ifdef CONFIG_SMP
230         struct sched_domain *sd;
231
232         /* For active balancing */
233         int active_balance;
234         int push_cpu;
235
236         task_t *migration_thread;
237         struct list_head migration_queue;
238 #endif
239
240 #ifdef CONFIG_SCHEDSTATS
241         /* latency stats */
242         struct sched_info rq_sched_info;
243
244         /* sys_sched_yield() stats */
245         unsigned long yld_exp_empty;
246         unsigned long yld_act_empty;
247         unsigned long yld_both_empty;
248         unsigned long yld_cnt;
249
250         /* schedule() stats */
251         unsigned long sched_switch;
252         unsigned long sched_cnt;
253         unsigned long sched_goidle;
254
255         /* try_to_wake_up() stats */
256         unsigned long ttwu_cnt;
257         unsigned long ttwu_local;
258 #endif
259 };
260
261 static DEFINE_PER_CPU(struct runqueue, runqueues);
262
263 /*
264  * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
265  * See detach_destroy_domains: synchronize_sched for details.
266  *
267  * The domain tree of any CPU may only be accessed from within
268  * preempt-disabled sections.
269  */
270 #define for_each_domain(cpu, domain) \
271 for (domain = rcu_dereference(cpu_rq(cpu)->sd); domain; domain = domain->parent)
272
273 #define cpu_rq(cpu)             (&per_cpu(runqueues, (cpu)))
274 #define this_rq()               (&__get_cpu_var(runqueues))
275 #define task_rq(p)              cpu_rq(task_cpu(p))
276 #define cpu_curr(cpu)           (cpu_rq(cpu)->curr)
277
278 #ifndef prepare_arch_switch
279 # define prepare_arch_switch(next)      do { } while (0)
280 #endif
281 #ifndef finish_arch_switch
282 # define finish_arch_switch(prev)       do { } while (0)
283 #endif
284
285 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
286 static inline int task_running(runqueue_t *rq, task_t *p)
287 {
288         return rq->curr == p;
289 }
290
291 static inline void prepare_lock_switch(runqueue_t *rq, task_t *next)
292 {
293 }
294
295 static inline void finish_lock_switch(runqueue_t *rq, task_t *prev)
296 {
297         spin_unlock_irq(&rq->lock);
298 }
299
300 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
301 static inline int task_running(runqueue_t *rq, task_t *p)
302 {
303 #ifdef CONFIG_SMP
304         return p->oncpu;
305 #else
306         return rq->curr == p;
307 #endif
308 }
309
310 static inline void prepare_lock_switch(runqueue_t *rq, task_t *next)
311 {
312 #ifdef CONFIG_SMP
313         /*
314          * We can optimise this out completely for !SMP, because the
315          * SMP rebalancing from interrupt is the only thing that cares
316          * here.
317          */
318         next->oncpu = 1;
319 #endif
320 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
321         spin_unlock_irq(&rq->lock);
322 #else
323         spin_unlock(&rq->lock);
324 #endif
325 }
326
327 static inline void finish_lock_switch(runqueue_t *rq, task_t *prev)
328 {
329 #ifdef CONFIG_SMP
330         /*
331          * After ->oncpu is cleared, the task can be moved to a different CPU.
332          * We must ensure this doesn't happen until the switch is completely
333          * finished.
334          */
335         smp_wmb();
336         prev->oncpu = 0;
337 #endif
338 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
339         local_irq_enable();
340 #endif
341 }
342 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
343
344 /*
345  * task_rq_lock - lock the runqueue a given task resides on and disable
346  * interrupts.  Note the ordering: we can safely lookup the task_rq without
347  * explicitly disabling preemption.
348  */
349 static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
350         __acquires(rq->lock)
351 {
352         struct runqueue *rq;
353
354 repeat_lock_task:
355         local_irq_save(*flags);
356         rq = task_rq(p);
357         spin_lock(&rq->lock);
358         if (unlikely(rq != task_rq(p))) {
359                 spin_unlock_irqrestore(&rq->lock, *flags);
360                 goto repeat_lock_task;
361         }
362         return rq;
363 }
364
365 static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
366         __releases(rq->lock)
367 {
368         spin_unlock_irqrestore(&rq->lock, *flags);
369 }
370
371 #ifdef CONFIG_SCHEDSTATS
372 /*
373  * bump this up when changing the output format or the meaning of an existing
374  * format, so that tools can adapt (or abort)
375  */
376 #define SCHEDSTAT_VERSION 12
377
378 static int show_schedstat(struct seq_file *seq, void *v)
379 {
380         int cpu;
381
382         seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION);
383         seq_printf(seq, "timestamp %lu\n", jiffies);
384         for_each_online_cpu(cpu) {
385                 runqueue_t *rq = cpu_rq(cpu);
386 #ifdef CONFIG_SMP
387                 struct sched_domain *sd;
388                 int dcnt = 0;
389 #endif
390
391                 /* runqueue-specific stats */
392                 seq_printf(seq,
393                     "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
394                     cpu, rq->yld_both_empty,
395                     rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt,
396                     rq->sched_switch, rq->sched_cnt, rq->sched_goidle,
397                     rq->ttwu_cnt, rq->ttwu_local,
398                     rq->rq_sched_info.cpu_time,
399                     rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt);
400
401                 seq_printf(seq, "\n");
402
403 #ifdef CONFIG_SMP
404                 /* domain-specific stats */
405                 preempt_disable();
406                 for_each_domain(cpu, sd) {
407                         enum idle_type itype;
408                         char mask_str[NR_CPUS];
409
410                         cpumask_scnprintf(mask_str, NR_CPUS, sd->span);
411                         seq_printf(seq, "domain%d %s", dcnt++, mask_str);
412                         for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES;
413                                         itype++) {
414                                 seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu",
415                                     sd->lb_cnt[itype],
416                                     sd->lb_balanced[itype],
417                                     sd->lb_failed[itype],
418                                     sd->lb_imbalance[itype],
419                                     sd->lb_gained[itype],
420                                     sd->lb_hot_gained[itype],
421                                     sd->lb_nobusyq[itype],
422                                     sd->lb_nobusyg[itype]);
423                         }
424                         seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n",
425                             sd->alb_cnt, sd->alb_failed, sd->alb_pushed,
426                             sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed,
427                             sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed,
428                             sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance);
429                 }
430                 preempt_enable();
431 #endif
432         }
433         return 0;
434 }
435
436 static int schedstat_open(struct inode *inode, struct file *file)
437 {
438         unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32);
439         char *buf = kmalloc(size, GFP_KERNEL);
440         struct seq_file *m;
441         int res;
442
443         if (!buf)
444                 return -ENOMEM;
445         res = single_open(file, show_schedstat, NULL);
446         if (!res) {
447                 m = file->private_data;
448                 m->buf = buf;
449                 m->size = size;
450         } else
451                 kfree(buf);
452         return res;
453 }
454
455 struct file_operations proc_schedstat_operations = {
456         .open    = schedstat_open,
457         .read    = seq_read,
458         .llseek  = seq_lseek,
459         .release = single_release,
460 };
461
462 # define schedstat_inc(rq, field)       do { (rq)->field++; } while (0)
463 # define schedstat_add(rq, field, amt)  do { (rq)->field += (amt); } while (0)
464 #else /* !CONFIG_SCHEDSTATS */
465 # define schedstat_inc(rq, field)       do { } while (0)
466 # define schedstat_add(rq, field, amt)  do { } while (0)
467 #endif
468
469 /*
470  * rq_lock - lock a given runqueue and disable interrupts.
471  */
472 static inline runqueue_t *this_rq_lock(void)
473         __acquires(rq->lock)
474 {
475         runqueue_t *rq;
476
477         local_irq_disable();
478         rq = this_rq();
479         spin_lock(&rq->lock);
480
481         return rq;
482 }
483
484 #ifdef CONFIG_SCHEDSTATS
485 /*
486  * Called when a process is dequeued from the active array and given
487  * the cpu.  We should note that with the exception of interactive
488  * tasks, the expired queue will become the active queue after the active
489  * queue is empty, without explicitly dequeuing and requeuing tasks in the
490  * expired queue.  (Interactive tasks may be requeued directly to the
491  * active queue, thus delaying tasks in the expired queue from running;
492  * see scheduler_tick()).
493  *
494  * This function is only called from sched_info_arrive(), rather than
495  * dequeue_task(). Even though a task may be queued and dequeued multiple
496  * times as it is shuffled about, we're really interested in knowing how
497  * long it was from the *first* time it was queued to the time that it
498  * finally hit a cpu.
499  */
500 static inline void sched_info_dequeued(task_t *t)
501 {
502         t->sched_info.last_queued = 0;
503 }
504
505 /*
506  * Called when a task finally hits the cpu.  We can now calculate how
507  * long it was waiting to run.  We also note when it began so that we
508  * can keep stats on how long its timeslice is.
509  */
510 static inline void sched_info_arrive(task_t *t)
511 {
512         unsigned long now = jiffies, diff = 0;
513         struct runqueue *rq = task_rq(t);
514
515         if (t->sched_info.last_queued)
516                 diff = now - t->sched_info.last_queued;
517         sched_info_dequeued(t);
518         t->sched_info.run_delay += diff;
519         t->sched_info.last_arrival = now;
520         t->sched_info.pcnt++;
521
522         if (!rq)
523                 return;
524
525         rq->rq_sched_info.run_delay += diff;
526         rq->rq_sched_info.pcnt++;
527 }
528
529 /*
530  * Called when a process is queued into either the active or expired
531  * array.  The time is noted and later used to determine how long we
532  * had to wait for us to reach the cpu.  Since the expired queue will
533  * become the active queue after active queue is empty, without dequeuing
534  * and requeuing any tasks, we are interested in queuing to either. It
535  * is unusual but not impossible for tasks to be dequeued and immediately
536  * requeued in the same or another array: this can happen in sched_yield(),
537  * set_user_nice(), and even load_balance() as it moves tasks from runqueue
538  * to runqueue.
539  *
540  * This function is only called from enqueue_task(), but also only updates
541  * the timestamp if it is already not set.  It's assumed that
542  * sched_info_dequeued() will clear that stamp when appropriate.
543  */
544 static inline void sched_info_queued(task_t *t)
545 {
546         if (!t->sched_info.last_queued)
547                 t->sched_info.last_queued = jiffies;
548 }
549
550 /*
551  * Called when a process ceases being the active-running process, either
552  * voluntarily or involuntarily.  Now we can calculate how long we ran.
553  */
554 static inline void sched_info_depart(task_t *t)
555 {
556         struct runqueue *rq = task_rq(t);
557         unsigned long diff = jiffies - t->sched_info.last_arrival;
558
559         t->sched_info.cpu_time += diff;
560
561         if (rq)
562                 rq->rq_sched_info.cpu_time += diff;
563 }
564
565 /*
566  * Called when tasks are switched involuntarily due, typically, to expiring
567  * their time slice.  (This may also be called when switching to or from
568  * the idle task.)  We are only called when prev != next.
569  */
570 static inline void sched_info_switch(task_t *prev, task_t *next)
571 {
572         struct runqueue *rq = task_rq(prev);
573
574         /*
575          * prev now departs the cpu.  It's not interesting to record
576          * stats about how efficient we were at scheduling the idle
577          * process, however.
578          */
579         if (prev != rq->idle)
580                 sched_info_depart(prev);
581
582         if (next != rq->idle)
583                 sched_info_arrive(next);
584 }
585 #else
586 #define sched_info_queued(t)            do { } while (0)
587 #define sched_info_switch(t, next)      do { } while (0)
588 #endif /* CONFIG_SCHEDSTATS */
589
590 /*
591  * Adding/removing a task to/from a priority array:
592  */
593 static void dequeue_task(struct task_struct *p, prio_array_t *array)
594 {
595         array->nr_active--;
596         list_del(&p->run_list);
597         if (list_empty(array->queue + p->prio))
598                 __clear_bit(p->prio, array->bitmap);
599 }
600
601 static void enqueue_task(struct task_struct *p, prio_array_t *array)
602 {
603         sched_info_queued(p);
604         list_add_tail(&p->run_list, array->queue + p->prio);
605         __set_bit(p->prio, array->bitmap);
606         array->nr_active++;
607         p->array = array;
608 }
609
610 /*
611  * Put task to the end of the run list without the overhead of dequeue
612  * followed by enqueue.
613  */
614 static void requeue_task(struct task_struct *p, prio_array_t *array)
615 {
616         list_move_tail(&p->run_list, array->queue + p->prio);
617 }
618
619 static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array)
620 {
621         list_add(&p->run_list, array->queue + p->prio);
622         __set_bit(p->prio, array->bitmap);
623         array->nr_active++;
624         p->array = array;
625 }
626
627 /*
628  * effective_prio - return the priority that is based on the static
629  * priority but is modified by bonuses/penalties.
630  *
631  * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
632  * into the -5 ... 0 ... +5 bonus/penalty range.
633  *
634  * We use 25% of the full 0...39 priority range so that:
635  *
636  * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
637  * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
638  *
639  * Both properties are important to certain workloads.
640  */
641 static int effective_prio(task_t *p)
642 {
643         int bonus, prio;
644
645         if (rt_task(p))
646                 return p->prio;
647
648         bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
649
650         prio = p->static_prio - bonus;
651         if (prio < MAX_RT_PRIO)
652                 prio = MAX_RT_PRIO;
653         if (prio > MAX_PRIO-1)
654                 prio = MAX_PRIO-1;
655         return prio;
656 }
657
658 /*
659  * __activate_task - move a task to the runqueue.
660  */
661 static inline void __activate_task(task_t *p, runqueue_t *rq)
662 {
663         enqueue_task(p, rq->active);
664         rq->nr_running++;
665 }
666
667 /*
668  * __activate_idle_task - move idle task to the _front_ of runqueue.
669  */
670 static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
671 {
672         enqueue_task_head(p, rq->active);
673         rq->nr_running++;
674 }
675
676 static int recalc_task_prio(task_t *p, unsigned long long now)
677 {
678         /* Caller must always ensure 'now >= p->timestamp' */
679         unsigned long long __sleep_time = now - p->timestamp;
680         unsigned long sleep_time;
681
682         if (__sleep_time > NS_MAX_SLEEP_AVG)
683                 sleep_time = NS_MAX_SLEEP_AVG;
684         else
685                 sleep_time = (unsigned long)__sleep_time;
686
687         if (likely(sleep_time > 0)) {
688                 /*
689                  * User tasks that sleep a long time are categorised as
690                  * idle and will get just interactive status to stay active &
691                  * prevent them suddenly becoming cpu hogs and starving
692                  * other processes.
693                  */
694                 if (p->mm && p->activated != -1 &&
695                         sleep_time > INTERACTIVE_SLEEP(p)) {
696                                 p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
697                                                 DEF_TIMESLICE);
698                 } else {
699                         /*
700                          * The lower the sleep avg a task has the more
701                          * rapidly it will rise with sleep time.
702                          */
703                         sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1;
704
705                         /*
706                          * Tasks waking from uninterruptible sleep are
707                          * limited in their sleep_avg rise as they
708                          * are likely to be waiting on I/O
709                          */
710                         if (p->activated == -1 && p->mm) {
711                                 if (p->sleep_avg >= INTERACTIVE_SLEEP(p))
712                                         sleep_time = 0;
713                                 else if (p->sleep_avg + sleep_time >=
714                                                 INTERACTIVE_SLEEP(p)) {
715                                         p->sleep_avg = INTERACTIVE_SLEEP(p);
716                                         sleep_time = 0;
717                                 }
718                         }
719
720                         /*
721                          * This code gives a bonus to interactive tasks.
722                          *
723                          * The boost works by updating the 'average sleep time'
724                          * value here, based on ->timestamp. The more time a
725                          * task spends sleeping, the higher the average gets -
726                          * and the higher the priority boost gets as well.
727                          */
728                         p->sleep_avg += sleep_time;
729
730                         if (p->sleep_avg > NS_MAX_SLEEP_AVG)
731                                 p->sleep_avg = NS_MAX_SLEEP_AVG;
732                 }
733         }
734
735         return effective_prio(p);
736 }
737
738 /*
739  * activate_task - move a task to the runqueue and do priority recalculation
740  *
741  * Update all the scheduling statistics stuff. (sleep average
742  * calculation, priority modifiers, etc.)
743  */
744 static void activate_task(task_t *p, runqueue_t *rq, int local)
745 {
746         unsigned long long now;
747
748         now = sched_clock();
749 #ifdef CONFIG_SMP
750         if (!local) {
751                 /* Compensate for drifting sched_clock */
752                 runqueue_t *this_rq = this_rq();
753                 now = (now - this_rq->timestamp_last_tick)
754                         + rq->timestamp_last_tick;
755         }
756 #endif
757
758         p->prio = recalc_task_prio(p, now);
759
760         /*
761          * This checks to make sure it's not an uninterruptible task
762          * that is now waking up.
763          */
764         if (!p->activated) {
765                 /*
766                  * Tasks which were woken up by interrupts (ie. hw events)
767                  * are most likely of interactive nature. So we give them
768                  * the credit of extending their sleep time to the period
769                  * of time they spend on the runqueue, waiting for execution
770                  * on a CPU, first time around:
771                  */
772                 if (in_interrupt())
773                         p->activated = 2;
774                 else {
775                         /*
776                          * Normal first-time wakeups get a credit too for
777                          * on-runqueue time, but it will be weighted down:
778                          */
779                         p->activated = 1;
780                 }
781         }
782         p->timestamp = now;
783
784         __activate_task(p, rq);
785 }
786
787 /*
788  * deactivate_task - remove a task from the runqueue.
789  */
790 static void deactivate_task(struct task_struct *p, runqueue_t *rq)
791 {
792         rq->nr_running--;
793         dequeue_task(p, p->array);
794         p->array = NULL;
795 }
796
797 /*
798  * resched_task - mark a task 'to be rescheduled now'.
799  *
800  * On UP this means the setting of the need_resched flag, on SMP it
801  * might also involve a cross-CPU call to trigger the scheduler on
802  * the target CPU.
803  */
804 #ifdef CONFIG_SMP
805 static void resched_task(task_t *p)
806 {
807         int need_resched, nrpolling;
808
809         assert_spin_locked(&task_rq(p)->lock);
810
811         /* minimise the chance of sending an interrupt to poll_idle() */
812         nrpolling = test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
813         need_resched = test_and_set_tsk_thread_flag(p,TIF_NEED_RESCHED);
814         nrpolling |= test_tsk_thread_flag(p,TIF_POLLING_NRFLAG);
815
816         if (!need_resched && !nrpolling && (task_cpu(p) != smp_processor_id()))
817                 smp_send_reschedule(task_cpu(p));
818 }
819 #else
820 static inline void resched_task(task_t *p)
821 {
822         set_tsk_need_resched(p);
823 }
824 #endif
825
826 /**
827  * task_curr - is this task currently executing on a CPU?
828  * @p: the task in question.
829  */
830 inline int task_curr(const task_t *p)
831 {
832         return cpu_curr(task_cpu(p)) == p;
833 }
834
835 #ifdef CONFIG_SMP
836 typedef struct {
837         struct list_head list;
838
839         task_t *task;
840         int dest_cpu;
841
842         struct completion done;
843 } migration_req_t;
844
845 /*
846  * The task's runqueue lock must be held.
847  * Returns true if you have to wait for migration thread.
848  */
849 static int migrate_task(task_t *p, int dest_cpu, migration_req_t *req)
850 {
851         runqueue_t *rq = task_rq(p);
852
853         /*
854          * If the task is not on a runqueue (and not running), then
855          * it is sufficient to simply update the task's cpu field.
856          */
857         if (!p->array && !task_running(rq, p)) {
858                 set_task_cpu(p, dest_cpu);
859                 return 0;
860         }
861
862         init_completion(&req->done);
863         req->task = p;
864         req->dest_cpu = dest_cpu;
865         list_add(&req->list, &rq->migration_queue);
866         return 1;
867 }
868
869 /*
870  * wait_task_inactive - wait for a thread to unschedule.
871  *
872  * The caller must ensure that the task *will* unschedule sometime soon,
873  * else this function might spin for a *long* time. This function can't
874  * be called with interrupts off, or it may introduce deadlock with
875  * smp_call_function() if an IPI is sent by the same process we are
876  * waiting to become inactive.
877  */
878 void wait_task_inactive(task_t *p)
879 {
880         unsigned long flags;
881         runqueue_t *rq;
882         int preempted;
883
884 repeat:
885         rq = task_rq_lock(p, &flags);
886         /* Must be off runqueue entirely, not preempted. */
887         if (unlikely(p->array || task_running(rq, p))) {
888                 /* If it's preempted, we yield.  It could be a while. */
889                 preempted = !task_running(rq, p);
890                 task_rq_unlock(rq, &flags);
891                 cpu_relax();
892                 if (preempted)
893                         yield();
894                 goto repeat;
895         }
896         task_rq_unlock(rq, &flags);
897 }
898
899 /***
900  * kick_process - kick a running thread to enter/exit the kernel
901  * @p: the to-be-kicked thread
902  *
903  * Cause a process which is running on another CPU to enter
904  * kernel-mode, without any delay. (to get signals handled.)
905  *
906  * NOTE: this function doesnt have to take the runqueue lock,
907  * because all it wants to ensure is that the remote task enters
908  * the kernel. If the IPI races and the task has been migrated
909  * to another CPU then no harm is done and the purpose has been
910  * achieved as well.
911  */
912 void kick_process(task_t *p)
913 {
914         int cpu;
915
916         preempt_disable();
917         cpu = task_cpu(p);
918         if ((cpu != smp_processor_id()) && task_curr(p))
919                 smp_send_reschedule(cpu);
920         preempt_enable();
921 }
922
923 /*
924  * Return a low guess at the load of a migration-source cpu.
925  *
926  * We want to under-estimate the load of migration sources, to
927  * balance conservatively.
928  */
929 static inline unsigned long source_load(int cpu, int type)
930 {
931         runqueue_t *rq = cpu_rq(cpu);
932         unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
933         if (type == 0)
934                 return load_now;
935
936         return min(rq->cpu_load[type-1], load_now);
937 }
938
939 /*
940  * Return a high guess at the load of a migration-target cpu
941  */
942 static inline unsigned long target_load(int cpu, int type)
943 {
944         runqueue_t *rq = cpu_rq(cpu);
945         unsigned long load_now = rq->nr_running * SCHED_LOAD_SCALE;
946         if (type == 0)
947                 return load_now;
948
949         return max(rq->cpu_load[type-1], load_now);
950 }
951
952 /*
953  * find_idlest_group finds and returns the least busy CPU group within the
954  * domain.
955  */
956 static struct sched_group *
957 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
958 {
959         struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups;
960         unsigned long min_load = ULONG_MAX, this_load = 0;
961         int load_idx = sd->forkexec_idx;
962         int imbalance = 100 + (sd->imbalance_pct-100)/2;
963
964         do {
965                 unsigned long load, avg_load;
966                 int local_group;
967                 int i;
968
969                 /* Skip over this group if it has no CPUs allowed */
970                 if (!cpus_intersects(group->cpumask, p->cpus_allowed))
971                         goto nextgroup;
972
973                 local_group = cpu_isset(this_cpu, group->cpumask);
974
975                 /* Tally up the load of all CPUs in the group */
976                 avg_load = 0;
977
978                 for_each_cpu_mask(i, group->cpumask) {
979                         /* Bias balancing toward cpus of our domain */
980                         if (local_group)
981                                 load = source_load(i, load_idx);
982                         else
983                                 load = target_load(i, load_idx);
984
985                         avg_load += load;
986                 }
987
988                 /* Adjust by relative CPU power of the group */
989                 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
990
991                 if (local_group) {
992                         this_load = avg_load;
993                         this = group;
994                 } else if (avg_load < min_load) {
995                         min_load = avg_load;
996                         idlest = group;
997                 }
998 nextgroup:
999                 group = group->next;
1000         } while (group != sd->groups);
1001
1002         if (!idlest || 100*this_load < imbalance*min_load)
1003                 return NULL;
1004         return idlest;
1005 }
1006
1007 /*
1008  * find_idlest_queue - find the idlest runqueue among the cpus in group.
1009  */
1010 static int
1011 find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
1012 {
1013         cpumask_t tmp;
1014         unsigned long load, min_load = ULONG_MAX;
1015         int idlest = -1;
1016         int i;
1017
1018         /* Traverse only the allowed CPUs */
1019         cpus_and(tmp, group->cpumask, p->cpus_allowed);
1020
1021         for_each_cpu_mask(i, tmp) {
1022                 load = source_load(i, 0);
1023
1024                 if (load < min_load || (load == min_load && i == this_cpu)) {
1025                         min_load = load;
1026                         idlest = i;
1027                 }
1028         }
1029
1030         return idlest;
1031 }
1032
1033 /*
1034  * sched_balance_self: balance the current task (running on cpu) in domains
1035  * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1036  * SD_BALANCE_EXEC.
1037  *
1038  * Balance, ie. select the least loaded group.
1039  *
1040  * Returns the target CPU number, or the same CPU if no balancing is needed.
1041  *
1042  * preempt must be disabled.
1043  */
1044 static int sched_balance_self(int cpu, int flag)
1045 {
1046         struct task_struct *t = current;
1047         struct sched_domain *tmp, *sd = NULL;
1048
1049         for_each_domain(cpu, tmp)
1050                 if (tmp->flags & flag)
1051                         sd = tmp;
1052
1053         while (sd) {
1054                 cpumask_t span;
1055                 struct sched_group *group;
1056                 int new_cpu;
1057                 int weight;
1058
1059                 span = sd->span;
1060                 group = find_idlest_group(sd, t, cpu);
1061                 if (!group)
1062                         goto nextlevel;
1063
1064                 new_cpu = find_idlest_cpu(group, t, cpu);
1065                 if (new_cpu == -1 || new_cpu == cpu)
1066                         goto nextlevel;
1067
1068                 /* Now try balancing at a lower domain level */
1069                 cpu = new_cpu;
1070 nextlevel:
1071                 sd = NULL;
1072                 weight = cpus_weight(span);
1073                 for_each_domain(cpu, tmp) {
1074                         if (weight <= cpus_weight(tmp->span))
1075                                 break;
1076                         if (tmp->flags & flag)
1077                                 sd = tmp;
1078                 }
1079                 /* while loop will break here if sd == NULL */
1080         }
1081
1082         return cpu;
1083 }
1084
1085 #endif /* CONFIG_SMP */
1086
1087 /*
1088  * wake_idle() will wake a task on an idle cpu if task->cpu is
1089  * not idle and an idle cpu is available.  The span of cpus to
1090  * search starts with cpus closest then further out as needed,
1091  * so we always favor a closer, idle cpu.
1092  *
1093  * Returns the CPU we should wake onto.
1094  */
1095 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1096 static int wake_idle(int cpu, task_t *p)
1097 {
1098         cpumask_t tmp;
1099         struct sched_domain *sd;
1100         int i;
1101
1102         if (idle_cpu(cpu))
1103                 return cpu;
1104
1105         for_each_domain(cpu, sd) {
1106                 if (sd->flags & SD_WAKE_IDLE) {
1107                         cpus_and(tmp, sd->span, p->cpus_allowed);
1108                         for_each_cpu_mask(i, tmp) {
1109                                 if (idle_cpu(i))
1110                                         return i;
1111                         }
1112                 }
1113                 else
1114                         break;
1115         }
1116         return cpu;
1117 }
1118 #else
1119 static inline int wake_idle(int cpu, task_t *p)
1120 {
1121         return cpu;
1122 }
1123 #endif
1124
1125 /***
1126  * try_to_wake_up - wake up a thread
1127  * @p: the to-be-woken-up thread
1128  * @state: the mask of task states that can be woken
1129  * @sync: do a synchronous wakeup?
1130  *
1131  * Put it on the run-queue if it's not already there. The "current"
1132  * thread is always on the run-queue (except when the actual
1133  * re-schedule is in progress), and as such you're allowed to do
1134  * the simpler "current->state = TASK_RUNNING" to mark yourself
1135  * runnable without the overhead of this.
1136  *
1137  * returns failure only if the task is already active.
1138  */
1139 static int try_to_wake_up(task_t *p, unsigned int state, int sync)
1140 {
1141         int cpu, this_cpu, success = 0;
1142         unsigned long flags;
1143         long old_state;
1144         runqueue_t *rq;
1145 #ifdef CONFIG_SMP
1146         unsigned long load, this_load;
1147         struct sched_domain *sd, *this_sd = NULL;
1148         int new_cpu;
1149 #endif
1150
1151         rq = task_rq_lock(p, &flags);
1152         old_state = p->state;
1153         if (!(old_state & state))
1154                 goto out;
1155
1156         if (p->array)
1157                 goto out_running;
1158
1159         cpu = task_cpu(p);
1160         this_cpu = smp_processor_id();
1161
1162 #ifdef CONFIG_SMP
1163         if (unlikely(task_running(rq, p)))
1164                 goto out_activate;
1165
1166         new_cpu = cpu;
1167
1168         schedstat_inc(rq, ttwu_cnt);
1169         if (cpu == this_cpu) {
1170                 schedstat_inc(rq, ttwu_local);
1171                 goto out_set_cpu;
1172         }
1173
1174         for_each_domain(this_cpu, sd) {
1175                 if (cpu_isset(cpu, sd->span)) {
1176                         schedstat_inc(sd, ttwu_wake_remote);
1177                         this_sd = sd;
1178                         break;
1179                 }
1180         }
1181
1182         if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
1183                 goto out_set_cpu;
1184
1185         /*
1186          * Check for affine wakeup and passive balancing possibilities.
1187          */
1188         if (this_sd) {
1189                 int idx = this_sd->wake_idx;
1190                 unsigned int imbalance;
1191
1192                 imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
1193
1194                 load = source_load(cpu, idx);
1195                 this_load = target_load(this_cpu, idx);
1196
1197                 new_cpu = this_cpu; /* Wake to this CPU if we can */
1198
1199                 if (this_sd->flags & SD_WAKE_AFFINE) {
1200                         unsigned long tl = this_load;
1201                         /*
1202                          * If sync wakeup then subtract the (maximum possible)
1203                          * effect of the currently running task from the load
1204                          * of the current CPU:
1205                          */
1206                         if (sync)
1207                                 tl -= SCHED_LOAD_SCALE;
1208
1209                         if ((tl <= load &&
1210                                 tl + target_load(cpu, idx) <= SCHED_LOAD_SCALE) ||
1211                                 100*(tl + SCHED_LOAD_SCALE) <= imbalance*load) {
1212                                 /*
1213                                  * This domain has SD_WAKE_AFFINE and
1214                                  * p is cache cold in this domain, and
1215                                  * there is no bad imbalance.
1216                                  */
1217                                 schedstat_inc(this_sd, ttwu_move_affine);
1218                                 goto out_set_cpu;
1219                         }
1220                 }
1221
1222                 /*
1223                  * Start passive balancing when half the imbalance_pct
1224                  * limit is reached.
1225                  */
1226                 if (this_sd->flags & SD_WAKE_BALANCE) {
1227                         if (imbalance*this_load <= 100*load) {
1228                                 schedstat_inc(this_sd, ttwu_move_balance);
1229                                 goto out_set_cpu;
1230                         }
1231                 }
1232         }
1233
1234         new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
1235 out_set_cpu:
1236         new_cpu = wake_idle(new_cpu, p);
1237         if (new_cpu != cpu) {
1238                 set_task_cpu(p, new_cpu);
1239                 task_rq_unlock(rq, &flags);
1240                 /* might preempt at this point */
1241                 rq = task_rq_lock(p, &flags);
1242                 old_state = p->state;
1243                 if (!(old_state & state))
1244                         goto out;
1245                 if (p->array)
1246                         goto out_running;
1247
1248                 this_cpu = smp_processor_id();
1249                 cpu = task_cpu(p);
1250         }
1251
1252 out_activate:
1253 #endif /* CONFIG_SMP */
1254         if (old_state == TASK_UNINTERRUPTIBLE) {
1255                 rq->nr_uninterruptible--;
1256                 /*
1257                  * Tasks on involuntary sleep don't earn
1258                  * sleep_avg beyond just interactive state.
1259                  */
1260                 p->activated = -1;
1261         }
1262
1263         /*
1264          * Tasks that have marked their sleep as noninteractive get
1265          * woken up without updating their sleep average. (i.e. their
1266          * sleep is handled in a priority-neutral manner, no priority
1267          * boost and no penalty.)
1268          */
1269         if (old_state & TASK_NONINTERACTIVE)
1270                 __activate_task(p, rq);
1271         else
1272                 activate_task(p, rq, cpu == this_cpu);
1273         /*
1274          * Sync wakeups (i.e. those types of wakeups where the waker
1275          * has indicated that it will leave the CPU in short order)
1276          * don't trigger a preemption, if the woken up task will run on
1277          * this cpu. (in this case the 'I will reschedule' promise of
1278          * the waker guarantees that the freshly woken up task is going
1279          * to be considered on this CPU.)
1280          */
1281         if (!sync || cpu != this_cpu) {
1282                 if (TASK_PREEMPTS_CURR(p, rq))
1283                         resched_task(rq->curr);
1284         }
1285         success = 1;
1286
1287 out_running:
1288         p->state = TASK_RUNNING;
1289 out:
1290         task_rq_unlock(rq, &flags);
1291
1292         return success;
1293 }
1294
1295 int fastcall wake_up_process(task_t *p)
1296 {
1297         return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
1298                                  TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0);
1299 }
1300
1301 EXPORT_SYMBOL(wake_up_process);
1302
1303 int fastcall wake_up_state(task_t *p, unsigned int state)
1304 {
1305         return try_to_wake_up(p, state, 0);
1306 }
1307
1308 /*
1309  * Perform scheduler related setup for a newly forked process p.
1310  * p is forked by current.
1311  */
1312 void fastcall sched_fork(task_t *p, int clone_flags)
1313 {
1314         int cpu = get_cpu();
1315
1316 #ifdef CONFIG_SMP
1317         cpu = sched_balance_self(cpu, SD_BALANCE_FORK);
1318 #endif
1319         set_task_cpu(p, cpu);
1320
1321         /*
1322          * We mark the process as running here, but have not actually
1323          * inserted it onto the runqueue yet. This guarantees that
1324          * nobody will actually run it, and a signal or other external
1325          * event cannot wake it up and insert it on the runqueue either.
1326          */
1327         p->state = TASK_RUNNING;
1328         INIT_LIST_HEAD(&p->run_list);
1329         p->array = NULL;
1330 #ifdef CONFIG_SCHEDSTATS
1331         memset(&p->sched_info, 0, sizeof(p->sched_info));
1332 #endif
1333 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1334         p->oncpu = 0;
1335 #endif
1336 #ifdef CONFIG_PREEMPT
1337         /* Want to start with kernel preemption disabled. */
1338         p->thread_info->preempt_count = 1;
1339 #endif
1340         /*
1341          * Share the timeslice between parent and child, thus the
1342          * total amount of pending timeslices in the system doesn't change,
1343          * resulting in more scheduling fairness.
1344          */
1345         local_irq_disable();
1346         p->time_slice = (current->time_slice + 1) >> 1;
1347         /*
1348          * The remainder of the first timeslice might be recovered by
1349          * the parent if the child exits early enough.
1350          */
1351         p->first_time_slice = 1;
1352         current->time_slice >>= 1;
1353         p->timestamp = sched_clock();
1354         if (unlikely(!current->time_slice)) {
1355                 /*
1356                  * This case is rare, it happens when the parent has only
1357                  * a single jiffy left from its timeslice. Taking the
1358                  * runqueue lock is not a problem.
1359                  */
1360                 current->time_slice = 1;
1361                 scheduler_tick();
1362         }
1363         local_irq_enable();
1364         put_cpu();
1365 }
1366
1367 /*
1368  * wake_up_new_task - wake up a newly created task for the first time.
1369  *
1370  * This function will do some initial scheduler statistics housekeeping
1371  * that must be done for every newly created context, then puts the task
1372  * on the runqueue and wakes it.
1373  */
1374 void fastcall wake_up_new_task(task_t *p, unsigned long clone_flags)
1375 {
1376         unsigned long flags;
1377         int this_cpu, cpu;
1378         runqueue_t *rq, *this_rq;
1379
1380         rq = task_rq_lock(p, &flags);
1381         BUG_ON(p->state != TASK_RUNNING);
1382         this_cpu = smp_processor_id();
1383         cpu = task_cpu(p);
1384
1385         /*
1386          * We decrease the sleep average of forking parents
1387          * and children as well, to keep max-interactive tasks
1388          * from forking tasks that are max-interactive. The parent
1389          * (current) is done further down, under its lock.
1390          */
1391         p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
1392                 CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1393
1394         p->prio = effective_prio(p);
1395
1396         if (likely(cpu == this_cpu)) {
1397                 if (!(clone_flags & CLONE_VM)) {
1398                         /*
1399                          * The VM isn't cloned, so we're in a good position to
1400                          * do child-runs-first in anticipation of an exec. This
1401                          * usually avoids a lot of COW overhead.
1402                          */
1403                         if (unlikely(!current->array))
1404                                 __activate_task(p, rq);
1405                         else {
1406                                 p->prio = current->prio;
1407                                 list_add_tail(&p->run_list, &current->run_list);
1408                                 p->array = current->array;
1409                                 p->array->nr_active++;
1410                                 rq->nr_running++;
1411                         }
1412                         set_need_resched();
1413                 } else
1414                         /* Run child last */
1415                         __activate_task(p, rq);
1416                 /*
1417                  * We skip the following code due to cpu == this_cpu
1418                  *
1419                  *   task_rq_unlock(rq, &flags);
1420                  *   this_rq = task_rq_lock(current, &flags);
1421                  */
1422                 this_rq = rq;
1423         } else {
1424                 this_rq = cpu_rq(this_cpu);
1425
1426                 /*
1427                  * Not the local CPU - must adjust timestamp. This should
1428                  * get optimised away in the !CONFIG_SMP case.
1429                  */
1430                 p->timestamp = (p->timestamp - this_rq->timestamp_last_tick)
1431                                         + rq->timestamp_last_tick;
1432                 __activate_task(p, rq);
1433                 if (TASK_PREEMPTS_CURR(p, rq))
1434                         resched_task(rq->curr);
1435
1436                 /*
1437                  * Parent and child are on different CPUs, now get the
1438                  * parent runqueue to update the parent's ->sleep_avg:
1439                  */
1440                 task_rq_unlock(rq, &flags);
1441                 this_rq = task_rq_lock(current, &flags);
1442         }
1443         current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
1444                 PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
1445         task_rq_unlock(this_rq, &flags);
1446 }
1447
1448 /*
1449  * Potentially available exiting-child timeslices are
1450  * retrieved here - this way the parent does not get
1451  * penalized for creating too many threads.
1452  *
1453  * (this cannot be used to 'generate' timeslices
1454  * artificially, because any timeslice recovered here
1455  * was given away by the parent in the first place.)
1456  */
1457 void fastcall sched_exit(task_t *p)
1458 {
1459         unsigned long flags;
1460         runqueue_t *rq;
1461
1462         /*
1463          * If the child was a (relative-) CPU hog then decrease
1464          * the sleep_avg of the parent as well.
1465          */
1466         rq = task_rq_lock(p->parent, &flags);
1467         if (p->first_time_slice) {
1468                 p->parent->time_slice += p->time_slice;
1469                 if (unlikely(p->parent->time_slice > task_timeslice(p)))
1470                         p->parent->time_slice = task_timeslice(p);
1471         }
1472         if (p->sleep_avg < p->parent->sleep_avg)
1473                 p->parent->sleep_avg = p->parent->sleep_avg /
1474                 (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg /
1475                 (EXIT_WEIGHT + 1);
1476         task_rq_unlock(rq, &flags);
1477 }
1478
1479 /**
1480  * prepare_task_switch - prepare to switch tasks
1481  * @rq: the runqueue preparing to switch
1482  * @next: the task we are going to switch to.
1483  *
1484  * This is called with the rq lock held and interrupts off. It must
1485  * be paired with a subsequent finish_task_switch after the context
1486  * switch.
1487  *
1488  * prepare_task_switch sets up locking and calls architecture specific
1489  * hooks.
1490  */
1491 static inline void prepare_task_switch(runqueue_t *rq, task_t *next)
1492 {
1493         prepare_lock_switch(rq, next);
1494         prepare_arch_switch(next);
1495 }
1496
1497 /**
1498  * finish_task_switch - clean up after a task-switch
1499  * @rq: runqueue associated with task-switch
1500  * @prev: the thread we just switched away from.
1501  *
1502  * finish_task_switch must be called after the context switch, paired
1503  * with a prepare_task_switch call before the context switch.
1504  * finish_task_switch will reconcile locking set up by prepare_task_switch,
1505  * and do any other architecture-specific cleanup actions.
1506  *
1507  * Note that we may have delayed dropping an mm in context_switch(). If
1508  * so, we finish that here outside of the runqueue lock.  (Doing it
1509  * with the lock held can cause deadlocks; see schedule() for
1510  * details.)
1511  */
1512 static inline void finish_task_switch(runqueue_t *rq, task_t *prev)
1513         __releases(rq->lock)
1514 {
1515         struct mm_struct *mm = rq->prev_mm;
1516         unsigned long prev_task_flags;
1517
1518         rq->prev_mm = NULL;
1519
1520         /*
1521          * A task struct has one reference for the use as "current".
1522          * If a task dies, then it sets EXIT_ZOMBIE in tsk->exit_state and
1523          * calls schedule one last time. The schedule call will never return,
1524          * and the scheduled task must drop that reference.
1525          * The test for EXIT_ZOMBIE must occur while the runqueue locks are
1526          * still held, otherwise prev could be scheduled on another cpu, die
1527          * there before we look at prev->state, and then the reference would
1528          * be dropped twice.
1529          *              Manfred Spraul <manfred@colorfullife.com>
1530          */
1531         prev_task_flags = prev->flags;
1532 #ifdef CONFIG_DEBUG_SPINLOCK
1533         /* this is a valid case when another task releases the spinlock */
1534         rq->lock.owner = current;
1535 #endif
1536         finish_arch_switch(prev);
1537         finish_lock_switch(rq, prev);
1538         if (mm)
1539                 mmdrop(mm);
1540         if (unlikely(prev_task_flags & PF_DEAD))
1541                 put_task_struct(prev);
1542 }
1543
1544 /**
1545  * schedule_tail - first thing a freshly forked thread must call.
1546  * @prev: the thread we just switched away from.
1547  */
1548 asmlinkage void schedule_tail(task_t *prev)
1549         __releases(rq->lock)
1550 {
1551         runqueue_t *rq = this_rq();
1552         finish_task_switch(rq, prev);
1553 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1554         /* In this case, finish_task_switch does not reenable preemption */
1555         preempt_enable();
1556 #endif
1557         if (current->set_child_tid)
1558                 put_user(current->pid, current->set_child_tid);
1559 }
1560
1561 /*
1562  * context_switch - switch to the new MM and the new
1563  * thread's register state.
1564  */
1565 static inline
1566 task_t * context_switch(runqueue_t *rq, task_t *prev, task_t *next)
1567 {
1568         struct mm_struct *mm = next->mm;
1569         struct mm_struct *oldmm = prev->active_mm;
1570
1571         if (unlikely(!mm)) {
1572                 next->active_mm = oldmm;
1573                 atomic_inc(&oldmm->mm_count);
1574                 enter_lazy_tlb(oldmm, next);
1575         } else
1576                 switch_mm(oldmm, mm, next);
1577
1578         if (unlikely(!prev->mm)) {
1579                 prev->active_mm = NULL;
1580                 WARN_ON(rq->prev_mm);
1581                 rq->prev_mm = oldmm;
1582         }
1583
1584         /* Here we just switch the register state and the stack. */
1585         switch_to(prev, next, prev);
1586
1587         return prev;
1588 }
1589
1590 /*
1591  * nr_running, nr_uninterruptible and nr_context_switches:
1592  *
1593  * externally visible scheduler statistics: current number of runnable
1594  * threads, current number of uninterruptible-sleeping threads, total
1595  * number of context switches performed since bootup.
1596  */
1597 unsigned long nr_running(void)
1598 {
1599         unsigned long i, sum = 0;
1600
1601         for_each_online_cpu(i)
1602                 sum += cpu_rq(i)->nr_running;
1603
1604         return sum;
1605 }
1606
1607 unsigned long nr_uninterruptible(void)
1608 {
1609         unsigned long i, sum = 0;
1610
1611         for_each_cpu(i)
1612                 sum += cpu_rq(i)->nr_uninterruptible;
1613
1614         /*
1615          * Since we read the counters lockless, it might be slightly
1616          * inaccurate. Do not allow it to go below zero though:
1617          */
1618         if (unlikely((long)sum < 0))
1619                 sum = 0;
1620
1621         return sum;
1622 }
1623
1624 unsigned long long nr_context_switches(void)
1625 {
1626         unsigned long long i, sum = 0;
1627
1628         for_each_cpu(i)
1629                 sum += cpu_rq(i)->nr_switches;
1630
1631         return sum;
1632 }
1633
1634 unsigned long nr_iowait(void)
1635 {
1636         unsigned long i, sum = 0;
1637
1638         for_each_cpu(i)
1639                 sum += atomic_read(&cpu_rq(i)->nr_iowait);
1640
1641         return sum;
1642 }
1643
1644 #ifdef CONFIG_SMP
1645
1646 /*
1647  * double_rq_lock - safely lock two runqueues
1648  *
1649  * Note this does not disable interrupts like task_rq_lock,
1650  * you need to do so manually before calling.
1651  */
1652 static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
1653         __acquires(rq1->lock)
1654         __acquires(rq2->lock)
1655 {
1656         if (rq1 == rq2) {
1657                 spin_lock(&rq1->lock);
1658                 __acquire(rq2->lock);   /* Fake it out ;) */
1659         } else {
1660                 if (rq1 < rq2) {
1661                         spin_lock(&rq1->lock);
1662                         spin_lock(&rq2->lock);
1663                 } else {
1664                         spin_lock(&rq2->lock);
1665                         spin_lock(&rq1->lock);
1666                 }
1667         }
1668 }
1669
1670 /*
1671  * double_rq_unlock - safely unlock two runqueues
1672  *
1673  * Note this does not restore interrupts like task_rq_unlock,
1674  * you need to do so manually after calling.
1675  */
1676 static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
1677         __releases(rq1->lock)
1678         __releases(rq2->lock)
1679 {
1680         spin_unlock(&rq1->lock);
1681         if (rq1 != rq2)
1682                 spin_unlock(&rq2->lock);
1683         else
1684                 __release(rq2->lock);
1685 }
1686
1687 /*
1688  * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1689  */
1690 static void double_lock_balance(runqueue_t *this_rq, runqueue_t *busiest)
1691         __releases(this_rq->lock)
1692         __acquires(busiest->lock)
1693         __acquires(this_rq->lock)
1694 {
1695         if (unlikely(!spin_trylock(&busiest->lock))) {
1696                 if (busiest < this_rq) {
1697                         spin_unlock(&this_rq->lock);
1698                         spin_lock(&busiest->lock);
1699                         spin_lock(&this_rq->lock);
1700                 } else
1701                         spin_lock(&busiest->lock);
1702         }
1703 }
1704
1705 /*
1706  * If dest_cpu is allowed for this process, migrate the task to it.
1707  * This is accomplished by forcing the cpu_allowed mask to only
1708  * allow dest_cpu, which will force the cpu onto dest_cpu.  Then
1709  * the cpu_allowed mask is restored.
1710  */
1711 static void sched_migrate_task(task_t *p, int dest_cpu)
1712 {
1713         migration_req_t req;
1714         runqueue_t *rq;
1715         unsigned long flags;
1716
1717         rq = task_rq_lock(p, &flags);
1718         if (!cpu_isset(dest_cpu, p->cpus_allowed)
1719             || unlikely(cpu_is_offline(dest_cpu)))
1720                 goto out;
1721
1722         /* force the process onto the specified CPU */
1723         if (migrate_task(p, dest_cpu, &req)) {
1724                 /* Need to wait for migration thread (might exit: take ref). */
1725                 struct task_struct *mt = rq->migration_thread;
1726                 get_task_struct(mt);
1727                 task_rq_unlock(rq, &flags);
1728                 wake_up_process(mt);
1729                 put_task_struct(mt);
1730                 wait_for_completion(&req.done);
1731                 return;
1732         }
1733 out:
1734         task_rq_unlock(rq, &flags);
1735 }
1736
1737 /*
1738  * sched_exec - execve() is a valuable balancing opportunity, because at
1739  * this point the task has the smallest effective memory and cache footprint.
1740  */
1741 void sched_exec(void)
1742 {
1743         int new_cpu, this_cpu = get_cpu();
1744         new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC);
1745         put_cpu();
1746         if (new_cpu != this_cpu)
1747                 sched_migrate_task(current, new_cpu);
1748 }
1749
1750 /*
1751  * pull_task - move a task from a remote runqueue to the local runqueue.
1752  * Both runqueues must be locked.
1753  */
1754 static inline
1755 void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p,
1756                runqueue_t *this_rq, prio_array_t *this_array, int this_cpu)
1757 {
1758         dequeue_task(p, src_array);
1759         src_rq->nr_running--;
1760         set_task_cpu(p, this_cpu);
1761         this_rq->nr_running++;
1762         enqueue_task(p, this_array);
1763         p->timestamp = (p->timestamp - src_rq->timestamp_last_tick)
1764                                 + this_rq->timestamp_last_tick;
1765         /*
1766          * Note that idle threads have a prio of MAX_PRIO, for this test
1767          * to be always true for them.
1768          */
1769         if (TASK_PREEMPTS_CURR(p, this_rq))
1770                 resched_task(this_rq->curr);
1771 }
1772
1773 /*
1774  * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
1775  */
1776 static inline
1777 int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
1778                      struct sched_domain *sd, enum idle_type idle,
1779                      int *all_pinned)
1780 {
1781         /*
1782          * We do not migrate tasks that are:
1783          * 1) running (obviously), or
1784          * 2) cannot be migrated to this CPU due to cpus_allowed, or
1785          * 3) are cache-hot on their current CPU.
1786          */
1787         if (!cpu_isset(this_cpu, p->cpus_allowed))
1788                 return 0;
1789         *all_pinned = 0;
1790
1791         if (task_running(rq, p))
1792                 return 0;
1793
1794         /*
1795          * Aggressive migration if:
1796          * 1) task is cache cold, or
1797          * 2) too many balance attempts have failed.
1798          */
1799
1800         if (sd->nr_balance_failed > sd->cache_nice_tries)
1801                 return 1;
1802
1803         if (task_hot(p, rq->timestamp_last_tick, sd))
1804                 return 0;
1805         return 1;
1806 }
1807
1808 /*
1809  * move_tasks tries to move up to max_nr_move tasks from busiest to this_rq,
1810  * as part of a balancing operation within "domain". Returns the number of
1811  * tasks moved.
1812  *
1813  * Called with both runqueues locked.
1814  */
1815 static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
1816                       unsigned long max_nr_move, struct sched_domain *sd,
1817                       enum idle_type idle, int *all_pinned)
1818 {
1819         prio_array_t *array, *dst_array;
1820         struct list_head *head, *curr;
1821         int idx, pulled = 0, pinned = 0;
1822         task_t *tmp;
1823
1824         if (max_nr_move == 0)
1825                 goto out;
1826
1827         pinned = 1;
1828
1829         /*
1830          * We first consider expired tasks. Those will likely not be
1831          * executed in the near future, and they are most likely to
1832          * be cache-cold, thus switching CPUs has the least effect
1833          * on them.
1834          */
1835         if (busiest->expired->nr_active) {
1836                 array = busiest->expired;
1837                 dst_array = this_rq->expired;
1838         } else {
1839                 array = busiest->active;
1840                 dst_array = this_rq->active;
1841         }
1842
1843 new_array:
1844         /* Start searching at priority 0: */
1845         idx = 0;
1846 skip_bitmap:
1847         if (!idx)
1848                 idx = sched_find_first_bit(array->bitmap);
1849         else
1850                 idx = find_next_bit(array->bitmap, MAX_PRIO, idx);
1851         if (idx >= MAX_PRIO) {
1852                 if (array == busiest->expired && busiest->active->nr_active) {
1853                         array = busiest->active;
1854                         dst_array = this_rq->active;
1855                         goto new_array;
1856                 }
1857                 goto out;
1858         }
1859
1860         head = array->queue + idx;
1861         curr = head->prev;
1862 skip_queue:
1863         tmp = list_entry(curr, task_t, run_list);
1864
1865         curr = curr->prev;
1866
1867         if (!can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) {
1868                 if (curr != head)
1869                         goto skip_queue;
1870                 idx++;
1871                 goto skip_bitmap;
1872         }
1873
1874 #ifdef CONFIG_SCHEDSTATS
1875         if (task_hot(tmp, busiest->timestamp_last_tick, sd))
1876                 schedstat_inc(sd, lb_hot_gained[idle]);
1877 #endif
1878
1879         pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu);
1880         pulled++;
1881
1882         /* We only want to steal up to the prescribed number of tasks. */
1883         if (pulled < max_nr_move) {
1884                 if (curr != head)
1885                         goto skip_queue;
1886                 idx++;
1887                 goto skip_bitmap;
1888         }
1889 out:
1890         /*
1891          * Right now, this is the only place pull_task() is called,
1892          * so we can safely collect pull_task() stats here rather than
1893          * inside pull_task().
1894          */
1895         schedstat_add(sd, lb_gained[idle], pulled);
1896
1897         if (all_pinned)
1898                 *all_pinned = pinned;
1899         return pulled;
1900 }
1901
1902 /*
1903  * find_busiest_group finds and returns the busiest CPU group within the
1904  * domain. It calculates and returns the number of tasks which should be
1905  * moved to restore balance via the imbalance parameter.
1906  */
1907 static struct sched_group *
1908 find_busiest_group(struct sched_domain *sd, int this_cpu,
1909                    unsigned long *imbalance, enum idle_type idle)
1910 {
1911         struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
1912         unsigned long max_load, avg_load, total_load, this_load, total_pwr;
1913         int load_idx;
1914
1915         max_load = this_load = total_load = total_pwr = 0;
1916         if (idle == NOT_IDLE)
1917                 load_idx = sd->busy_idx;
1918         else if (idle == NEWLY_IDLE)
1919                 load_idx = sd->newidle_idx;
1920         else
1921                 load_idx = sd->idle_idx;
1922
1923         do {
1924                 unsigned long load;
1925                 int local_group;
1926                 int i;
1927
1928                 local_group = cpu_isset(this_cpu, group->cpumask);
1929
1930                 /* Tally up the load of all CPUs in the group */
1931                 avg_load = 0;
1932
1933                 for_each_cpu_mask(i, group->cpumask) {
1934                         /* Bias balancing toward cpus of our domain */
1935                         if (local_group)
1936                                 load = target_load(i, load_idx);
1937                         else
1938                                 load = source_load(i, load_idx);
1939
1940                         avg_load += load;
1941                 }
1942
1943                 total_load += avg_load;
1944                 total_pwr += group->cpu_power;
1945
1946                 /* Adjust by relative CPU power of the group */
1947                 avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
1948
1949                 if (local_group) {
1950                         this_load = avg_load;
1951                         this = group;
1952                 } else if (avg_load > max_load) {
1953                         max_load = avg_load;
1954                         busiest = group;
1955                 }
1956                 group = group->next;
1957         } while (group != sd->groups);
1958
1959         if (!busiest || this_load >= max_load)
1960                 goto out_balanced;
1961
1962         avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
1963
1964         if (this_load >= avg_load ||
1965                         100*max_load <= sd->imbalance_pct*this_load)
1966                 goto out_balanced;
1967
1968         /*
1969          * We're trying to get all the cpus to the average_load, so we don't
1970          * want to push ourselves above the average load, nor do we wish to
1971          * reduce the max loaded cpu below the average load, as either of these
1972          * actions would just result in more rebalancing later, and ping-pong
1973          * tasks around. Thus we look for the minimum possible imbalance.
1974          * Negative imbalances (*we* are more loaded than anyone else) will
1975          * be counted as no imbalance for these purposes -- we can't fix that
1976          * by pulling tasks to us.  Be careful of negative numbers as they'll
1977          * appear as very large values with unsigned longs.
1978          */
1979         /* How much load to actually move to equalise the imbalance */
1980         *imbalance = min((max_load - avg_load) * busiest->cpu_power,
1981                                 (avg_load - this_load) * this->cpu_power)
1982                         / SCHED_LOAD_SCALE;
1983
1984         if (*imbalance < SCHED_LOAD_SCALE) {
1985                 unsigned long pwr_now = 0, pwr_move = 0;
1986                 unsigned long tmp;
1987
1988                 if (max_load - this_load >= SCHED_LOAD_SCALE*2) {
1989                         *imbalance = 1;
1990                         return busiest;
1991                 }
1992
1993                 /*
1994                  * OK, we don't have enough imbalance to justify moving tasks,
1995                  * however we may be able to increase total CPU power used by
1996                  * moving them.
1997                  */
1998
1999                 pwr_now += busiest->cpu_power*min(SCHED_LOAD_SCALE, max_load);
2000                 pwr_now += this->cpu_power*min(SCHED_LOAD_SCALE, this_load);
2001                 pwr_now /= SCHED_LOAD_SCALE;
2002
2003                 /* Amount of load we'd subtract */
2004                 tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/busiest->cpu_power;
2005                 if (max_load > tmp)
2006                         pwr_move += busiest->cpu_power*min(SCHED_LOAD_SCALE,
2007                                                         max_load - tmp);
2008
2009                 /* Amount of load we'd add */
2010                 if (max_load*busiest->cpu_power <
2011                                 SCHED_LOAD_SCALE*SCHED_LOAD_SCALE)
2012                         tmp = max_load*busiest->cpu_power/this->cpu_power;
2013                 else
2014                         tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
2015                 pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
2016                 pwr_move /= SCHED_LOAD_SCALE;
2017
2018                 /* Move if we gain throughput */
2019                 if (pwr_move <= pwr_now)
2020                         goto out_balanced;
2021
2022                 *imbalance = 1;
2023                 return busiest;
2024         }
2025
2026         /* Get rid of the scaling factor, rounding down as we divide */
2027         *imbalance = *imbalance / SCHED_LOAD_SCALE;
2028         return busiest;
2029
2030 out_balanced:
2031
2032         *imbalance = 0;
2033         return NULL;
2034 }
2035
2036 /*
2037  * find_busiest_queue - find the busiest runqueue among the cpus in group.
2038  */
2039 static runqueue_t *find_busiest_queue(struct sched_group *group)
2040 {
2041         unsigned long load, max_load = 0;
2042         runqueue_t *busiest = NULL;
2043         int i;
2044
2045         for_each_cpu_mask(i, group->cpumask) {
2046                 load = source_load(i, 0);
2047
2048                 if (load > max_load) {
2049                         max_load = load;
2050                         busiest = cpu_rq(i);
2051                 }
2052         }
2053
2054         return busiest;
2055 }
2056
2057 /*
2058  * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2059  * so long as it is large enough.
2060  */
2061 #define MAX_PINNED_INTERVAL     512
2062
2063 /*
2064  * Check this_cpu to ensure it is balanced within domain. Attempt to move
2065  * tasks if there is an imbalance.
2066  *
2067  * Called with this_rq unlocked.
2068  */
2069 static int load_balance(int this_cpu, runqueue_t *this_rq,
2070                         struct sched_domain *sd, enum idle_type idle)
2071 {
2072         struct sched_group *group;
2073         runqueue_t *busiest;
2074         unsigned long imbalance;
2075         int nr_moved, all_pinned = 0;
2076         int active_balance = 0;
2077
2078         spin_lock(&this_rq->lock);
2079         schedstat_inc(sd, lb_cnt[idle]);
2080
2081         group = find_busiest_group(sd, this_cpu, &imbalance, idle);
2082         if (!group) {
2083                 schedstat_inc(sd, lb_nobusyg[idle]);
2084                 goto out_balanced;
2085         }
2086
2087         busiest = find_busiest_queue(group);
2088         if (!busiest) {
2089                 schedstat_inc(sd, lb_nobusyq[idle]);
2090                 goto out_balanced;
2091         }
2092
2093         BUG_ON(busiest == this_rq);
2094
2095         schedstat_add(sd, lb_imbalance[idle], imbalance);
2096
2097         nr_moved = 0;
2098         if (busiest->nr_running > 1) {
2099                 /*
2100                  * Attempt to move tasks. If find_busiest_group has found
2101                  * an imbalance but busiest->nr_running <= 1, the group is
2102                  * still unbalanced. nr_moved simply stays zero, so it is
2103                  * correctly treated as an imbalance.
2104                  */
2105                 double_lock_balance(this_rq, busiest);
2106                 nr_moved = move_tasks(this_rq, this_cpu, busiest,
2107                                                 imbalance, sd, idle,
2108                                                 &all_pinned);
2109                 spin_unlock(&busiest->lock);
2110
2111                 /* All tasks on this runqueue were pinned by CPU affinity */
2112                 if (unlikely(all_pinned))
2113                         goto out_balanced;
2114         }
2115
2116         spin_unlock(&this_rq->lock);
2117
2118         if (!nr_moved) {
2119                 schedstat_inc(sd, lb_failed[idle]);
2120                 sd->nr_balance_failed++;
2121
2122                 if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
2123
2124                         spin_lock(&busiest->lock);
2125                         if (!busiest->active_balance) {
2126                                 busiest->active_balance = 1;
2127                                 busiest->push_cpu = this_cpu;
2128                                 active_balance = 1;
2129                         }
2130                         spin_unlock(&busiest->lock);
2131                         if (active_balance)
2132                                 wake_up_process(busiest->migration_thread);
2133
2134                         /*
2135                          * We've kicked active balancing, reset the failure
2136                          * counter.
2137                          */
2138                         sd->nr_balance_failed = sd->cache_nice_tries+1;
2139                 }
2140         } else
2141                 sd->nr_balance_failed = 0;
2142
2143         if (likely(!active_balance)) {
2144                 /* We were unbalanced, so reset the balancing interval */
2145                 sd->balance_interval = sd->min_interval;
2146         } else {
2147                 /*
2148                  * If we've begun active balancing, start to back off. This
2149                  * case may not be covered by the all_pinned logic if there
2150                  * is only 1 task on the busy runqueue (because we don't call
2151                  * move_tasks).
2152                  */
2153                 if (sd->balance_interval < sd->max_interval)
2154                         sd->balance_interval *= 2;
2155         }
2156
2157         return nr_moved;
2158
2159 out_balanced:
2160         spin_unlock(&this_rq->lock);
2161
2162         schedstat_inc(sd, lb_balanced[idle]);
2163
2164         sd->nr_balance_failed = 0;
2165         /* tune up the balancing interval */
2166         if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
2167                         (sd->balance_interval < sd->max_interval))
2168                 sd->balance_interval *= 2;
2169
2170         return 0;
2171 }
2172
2173 /*
2174  * Check this_cpu to ensure it is balanced within domain. Attempt to move
2175  * tasks if there is an imbalance.
2176  *
2177  * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2178  * this_rq is locked.
2179  */
2180 static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
2181                                 struct sched_domain *sd)
2182 {
2183         struct sched_group *group;
2184         runqueue_t *busiest = NULL;
2185         unsigned long imbalance;
2186         int nr_moved = 0;
2187
2188         schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);
2189         group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);
2190         if (!group) {
2191                 schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);
2192                 goto out_balanced;
2193         }
2194
2195         busiest = find_busiest_queue(group);
2196         if (!busiest) {
2197                 schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);
2198                 goto out_balanced;
2199         }
2200
2201         BUG_ON(busiest == this_rq);
2202
2203         /* Attempt to move tasks */
2204         double_lock_balance(this_rq, busiest);
2205
2206         schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
2207         nr_moved = move_tasks(this_rq, this_cpu, busiest,
2208                                         imbalance, sd, NEWLY_IDLE, NULL);
2209         if (!nr_moved)
2210                 schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
2211         else
2212                 sd->nr_balance_failed = 0;
2213
2214         spin_unlock(&busiest->lock);
2215         return nr_moved;
2216
2217 out_balanced:
2218         schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);
2219         sd->nr_balance_failed = 0;
2220         return 0;
2221 }
2222
2223 /*
2224  * idle_balance is called by schedule() if this_cpu is about to become
2225  * idle. Attempts to pull tasks from other CPUs.
2226  */
2227 static inline void idle_balance(int this_cpu, runqueue_t *this_rq)
2228 {
2229         struct sched_domain *sd;
2230
2231         for_each_domain(this_cpu, sd) {
2232                 if (sd->flags & SD_BALANCE_NEWIDLE) {
2233                         if (load_balance_newidle(this_cpu, this_rq, sd)) {
2234                                 /* We've pulled tasks over so stop searching */
2235                                 break;
2236                         }
2237                 }
2238         }
2239 }
2240
2241 /*
2242  * active_load_balance is run by migration threads. It pushes running tasks
2243  * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2244  * running on each physical CPU where possible, and avoids physical /
2245  * logical imbalances.
2246  *
2247  * Called with busiest_rq locked.
2248  */
2249 static void active_load_balance(runqueue_t *busiest_rq, int busiest_cpu)
2250 {
2251         struct sched_domain *sd;
2252         runqueue_t *target_rq;
2253         int target_cpu = busiest_rq->push_cpu;
2254
2255         if (busiest_rq->nr_running <= 1)
2256                 /* no task to move */
2257                 return;
2258
2259         target_rq = cpu_rq(target_cpu);
2260
2261         /*
2262          * This condition is "impossible", if it occurs
2263          * we need to fix it.  Originally reported by
2264          * Bjorn Helgaas on a 128-cpu setup.
2265          */
2266         BUG_ON(busiest_rq == target_rq);
2267
2268         /* move a task from busiest_rq to target_rq */
2269         double_lock_balance(busiest_rq, target_rq);
2270
2271         /* Search for an sd spanning us and the target CPU. */
2272         for_each_domain(target_cpu, sd)
2273                 if ((sd->flags & SD_LOAD_BALANCE) &&
2274                         cpu_isset(busiest_cpu, sd->span))
2275                                 break;
2276
2277         if (unlikely(sd == NULL))
2278                 goto out;
2279
2280         schedstat_inc(sd, alb_cnt);
2281
2282         if (move_tasks(target_rq, target_cpu, busiest_rq, 1, sd, SCHED_IDLE, NULL))
2283                 schedstat_inc(sd, alb_pushed);
2284         else
2285                 schedstat_inc(sd, alb_failed);
2286 out:
2287         spin_unlock(&target_rq->lock);
2288 }
2289
2290 /*
2291  * rebalance_tick will get called every timer tick, on every CPU.
2292  *
2293  * It checks each scheduling domain to see if it is due to be balanced,
2294  * and initiates a balancing operation if so.
2295  *
2296  * Balancing parameters are set up in arch_init_sched_domains.
2297  */
2298
2299 /* Don't have all balancing operations going off at once */
2300 #define CPU_OFFSET(cpu) (HZ * cpu / NR_CPUS)
2301
2302 static void rebalance_tick(int this_cpu, runqueue_t *this_rq,
2303                            enum idle_type idle)
2304 {
2305         unsigned long old_load, this_load;
2306         unsigned long j = jiffies + CPU_OFFSET(this_cpu);
2307         struct sched_domain *sd;
2308         int i;
2309
2310         this_load = this_rq->nr_running * SCHED_LOAD_SCALE;
2311         /* Update our load */
2312         for (i = 0; i < 3; i++) {
2313                 unsigned long new_load = this_load;
2314                 int scale = 1 << i;
2315                 old_load = this_rq->cpu_load[i];
2316                 /*
2317                  * Round up the averaging division if load is increasing. This
2318                  * prevents us from getting stuck on 9 if the load is 10, for
2319                  * example.
2320                  */
2321                 if (new_load > old_load)
2322                         new_load += scale-1;
2323                 this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale;
2324         }
2325
2326         for_each_domain(this_cpu, sd) {
2327                 unsigned long interval;
2328
2329                 if (!(sd->flags & SD_LOAD_BALANCE))
2330                         continue;
2331
2332                 interval = sd->balance_interval;
2333                 if (idle != SCHED_IDLE)
2334                         interval *= sd->busy_factor;
2335
2336                 /* scale ms to jiffies */
2337                 interval = msecs_to_jiffies(interval);
2338                 if (unlikely(!interval))
2339                         interval = 1;
2340
2341                 if (j - sd->last_balance >= interval) {
2342                         if (load_balance(this_cpu, this_rq, sd, idle)) {
2343                                 /* We've pulled tasks over so no longer idle */
2344                                 idle = NOT_IDLE;
2345                         }
2346                         sd->last_balance += interval;
2347                 }
2348         }
2349 }
2350 #else
2351 /*
2352  * on UP we do not need to balance between CPUs:
2353  */
2354 static inline void rebalance_tick(int cpu, runqueue_t *rq, enum idle_type idle)
2355 {
2356 }
2357 static inline void idle_balance(int cpu, runqueue_t *rq)
2358 {
2359 }
2360 #endif
2361
2362 static inline int wake_priority_sleeper(runqueue_t *rq)
2363 {
2364         int ret = 0;
2365 #ifdef CONFIG_SCHED_SMT
2366         spin_lock(&rq->lock);
2367         /*
2368          * If an SMT sibling task has been put to sleep for priority
2369          * reasons reschedule the idle task to see if it can now run.
2370          */
2371         if (rq->nr_running) {
2372                 resched_task(rq->idle);
2373                 ret = 1;
2374         }
2375         spin_unlock(&rq->lock);
2376 #endif
2377         return ret;
2378 }
2379
2380 DEFINE_PER_CPU(struct kernel_stat, kstat);
2381
2382 EXPORT_PER_CPU_SYMBOL(kstat);
2383
2384 /*
2385  * This is called on clock ticks and on context switches.
2386  * Bank in p->sched_time the ns elapsed since the last tick or switch.
2387  */
2388 static inline void update_cpu_clock(task_t *p, runqueue_t *rq,
2389                                     unsigned long long now)
2390 {
2391         unsigned long long last = max(p->timestamp, rq->timestamp_last_tick);
2392         p->sched_time += now - last;
2393 }
2394
2395 /*
2396  * Return current->sched_time plus any more ns on the sched_clock
2397  * that have not yet been banked.
2398  */
2399 unsigned long long current_sched_time(const task_t *tsk)
2400 {
2401         unsigned long long ns;
2402         unsigned long flags;
2403         local_irq_save(flags);
2404         ns = max(tsk->timestamp, task_rq(tsk)->timestamp_last_tick);
2405         ns = tsk->sched_time + (sched_clock() - ns);
2406         local_irq_restore(flags);
2407         return ns;
2408 }
2409
2410 /*
2411  * We place interactive tasks back into the active array, if possible.
2412  *
2413  * To guarantee that this does not starve expired tasks we ignore the
2414  * interactivity of a task if the first expired task had to wait more
2415  * than a 'reasonable' amount of time. This deadline timeout is
2416  * load-dependent, as the frequency of array switched decreases with
2417  * increasing number of running tasks. We also ignore the interactivity
2418  * if a better static_prio task has expired:
2419  */
2420 #define EXPIRED_STARVING(rq) \
2421         ((STARVATION_LIMIT && ((rq)->expired_timestamp && \
2422                 (jiffies - (rq)->expired_timestamp >= \
2423                         STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \
2424                         ((rq)->curr->static_prio > (rq)->best_expired_prio))
2425
2426 /*
2427  * Account user cpu time to a process.
2428  * @p: the process that the cpu time gets accounted to
2429  * @hardirq_offset: the offset to subtract from hardirq_count()
2430  * @cputime: the cpu time spent in user space since the last update
2431  */
2432 void account_user_time(struct task_struct *p, cputime_t cputime)
2433 {
2434         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2435         cputime64_t tmp;
2436
2437         p->utime = cputime_add(p->utime, cputime);
2438
2439         /* Add user time to cpustat. */
2440         tmp = cputime_to_cputime64(cputime);
2441         if (TASK_NICE(p) > 0)
2442                 cpustat->nice = cputime64_add(cpustat->nice, tmp);
2443         else
2444                 cpustat->user = cputime64_add(cpustat->user, tmp);
2445 }
2446
2447 /*
2448  * Account system cpu time to a process.
2449  * @p: the process that the cpu time gets accounted to
2450  * @hardirq_offset: the offset to subtract from hardirq_count()
2451  * @cputime: the cpu time spent in kernel space since the last update
2452  */
2453 void account_system_time(struct task_struct *p, int hardirq_offset,
2454                          cputime_t cputime)
2455 {
2456         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2457         runqueue_t *rq = this_rq();
2458         cputime64_t tmp;
2459
2460         p->stime = cputime_add(p->stime, cputime);
2461
2462         /* Add system time to cpustat. */
2463         tmp = cputime_to_cputime64(cputime);
2464         if (hardirq_count() - hardirq_offset)
2465                 cpustat->irq = cputime64_add(cpustat->irq, tmp);
2466         else if (softirq_count())
2467                 cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
2468         else if (p != rq->idle)
2469                 cpustat->system = cputime64_add(cpustat->system, tmp);
2470         else if (atomic_read(&rq->nr_iowait) > 0)
2471                 cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
2472         else
2473                 cpustat->idle = cputime64_add(cpustat->idle, tmp);
2474         /* Account for system time used */
2475         acct_update_integrals(p);
2476         /* Update rss highwater mark */
2477         update_mem_hiwater(p);
2478 }
2479
2480 /*
2481  * Account for involuntary wait time.
2482  * @p: the process from which the cpu time has been stolen
2483  * @steal: the cpu time spent in involuntary wait
2484  */
2485 void account_steal_time(struct task_struct *p, cputime_t steal)
2486 {
2487         struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2488         cputime64_t tmp = cputime_to_cputime64(steal);
2489         runqueue_t *rq = this_rq();
2490
2491         if (p == rq->idle) {
2492                 p->stime = cputime_add(p->stime, steal);
2493                 if (atomic_read(&rq->nr_iowait) > 0)
2494                         cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
2495                 else
2496                         cpustat->idle = cputime64_add(cpustat->idle, tmp);
2497         } else
2498                 cpustat->steal = cputime64_add(cpustat->steal, tmp);
2499 }
2500
2501 /*
2502  * This function gets called by the timer code, with HZ frequency.
2503  * We call it with interrupts disabled.
2504  *
2505  * It also gets called by the fork code, when changing the parent's
2506  * timeslices.
2507  */
2508 void scheduler_tick(void)
2509 {
2510         int cpu = smp_processor_id();
2511         runqueue_t *rq = this_rq();
2512         task_t *p = current;
2513         unsigned long long now = sched_clock();
2514
2515         update_cpu_clock(p, rq, now);
2516
2517         rq->timestamp_last_tick = now;
2518
2519         if (p == rq->idle) {
2520                 if (wake_priority_sleeper(rq))
2521                         goto out;
2522                 rebalance_tick(cpu, rq, SCHED_IDLE);
2523                 return;
2524         }
2525
2526         /* Task might have expired already, but not scheduled off yet */
2527         if (p->array != rq->active) {
2528                 set_tsk_need_resched(p);
2529                 goto out;
2530         }
2531         spin_lock(&rq->lock);
2532         /*
2533          * The task was running during this tick - update the
2534          * time slice counter. Note: we do not update a thread's
2535          * priority until it either goes to sleep or uses up its
2536          * timeslice. This makes it possible for interactive tasks
2537          * to use up their timeslices at their highest priority levels.
2538          */
2539         if (rt_task(p)) {
2540                 /*
2541                  * RR tasks need a special form of timeslice management.
2542                  * FIFO tasks have no timeslices.
2543                  */
2544                 if ((p->policy == SCHED_RR) && !--p->time_slice) {
2545                         p->time_slice = task_timeslice(p);
2546                         p->first_time_slice = 0;
2547                         set_tsk_need_resched(p);
2548
2549                         /* put it at the end of the queue: */
2550                         requeue_task(p, rq->active);
2551                 }
2552                 goto out_unlock;
2553         }
2554         if (!--p->time_slice) {
2555                 dequeue_task(p, rq->active);
2556                 set_tsk_need_resched(p);
2557                 p->prio = effective_prio(p);
2558                 p->time_slice = task_timeslice(p);
2559                 p->first_time_slice = 0;
2560
2561                 if (!rq->expired_timestamp)
2562                         rq->expired_timestamp = jiffies;
2563                 if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) {
2564                         enqueue_task(p, rq->expired);
2565                         if (p->static_prio < rq->best_expired_prio)
2566                                 rq->best_expired_prio = p->static_prio;
2567                 } else
2568                         enqueue_task(p, rq->active);
2569         } else {
2570                 /*
2571                  * Prevent a too long timeslice allowing a task to monopolize
2572                  * the CPU. We do this by splitting up the timeslice into
2573                  * smaller pieces.
2574                  *
2575                  * Note: this does not mean the task's timeslices expire or
2576                  * get lost in any way, they just might be preempted by
2577                  * another task of equal priority. (one with higher
2578                  * priority would have preempted this task already.) We
2579                  * requeue this task to the end of the list on this priority
2580                  * level, which is in essence a round-robin of tasks with
2581                  * equal priority.
2582                  *
2583                  * This only applies to tasks in the interactive
2584                  * delta range with at least TIMESLICE_GRANULARITY to requeue.
2585                  */
2586                 if (TASK_INTERACTIVE(p) && !((task_timeslice(p) -
2587                         p->time_slice) % TIMESLICE_GRANULARITY(p)) &&
2588                         (p->time_slice >= TIMESLICE_GRANULARITY(p)) &&
2589                         (p->array == rq->active)) {
2590
2591                         requeue_task(p, rq->active);
2592                         set_tsk_need_resched(p);
2593                 }
2594         }
2595 out_unlock:
2596         spin_unlock(&rq->lock);
2597 out:
2598         rebalance_tick(cpu, rq, NOT_IDLE);
2599 }
2600
2601 #ifdef CONFIG_SCHED_SMT
2602 static inline void wakeup_busy_runqueue(runqueue_t *rq)
2603 {
2604         /* If an SMT runqueue is sleeping due to priority reasons wake it up */
2605         if (rq->curr == rq->idle && rq->nr_running)
2606                 resched_task(rq->idle);
2607 }
2608
2609 static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
2610 {
2611         struct sched_domain *tmp, *sd = NULL;
2612         cpumask_t sibling_map;
2613         int i;
2614
2615         for_each_domain(this_cpu, tmp)
2616                 if (tmp->flags & SD_SHARE_CPUPOWER)
2617                         sd = tmp;
2618
2619         if (!sd)
2620                 return;
2621
2622         /*
2623          * Unlock the current runqueue because we have to lock in
2624          * CPU order to avoid deadlocks. Caller knows that we might
2625          * unlock. We keep IRQs disabled.
2626          */
2627         spin_unlock(&this_rq->lock);
2628
2629         sibling_map = sd->span;
2630
2631         for_each_cpu_mask(i, sibling_map)
2632                 spin_lock(&cpu_rq(i)->lock);
2633         /*
2634          * We clear this CPU from the mask. This both simplifies the
2635          * inner loop and keps this_rq locked when we exit:
2636          */
2637         cpu_clear(this_cpu, sibling_map);
2638
2639         for_each_cpu_mask(i, sibling_map) {
2640                 runqueue_t *smt_rq = cpu_rq(i);
2641
2642                 wakeup_busy_runqueue(smt_rq);
2643         }
2644
2645         for_each_cpu_mask(i, sibling_map)
2646                 spin_unlock(&cpu_rq(i)->lock);
2647         /*
2648          * We exit with this_cpu's rq still held and IRQs
2649          * still disabled:
2650          */
2651 }
2652
2653 /*
2654  * number of 'lost' timeslices this task wont be able to fully
2655  * utilize, if another task runs on a sibling. This models the
2656  * slowdown effect of other tasks running on siblings:
2657  */
2658 static inline unsigned long smt_slice(task_t *p, struct sched_domain *sd)
2659 {
2660         return p->time_slice * (100 - sd->per_cpu_gain) / 100;
2661 }
2662
2663 static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
2664 {
2665         struct sched_domain *tmp, *sd = NULL;
2666         cpumask_t sibling_map;
2667         prio_array_t *array;
2668         int ret = 0, i;
2669         task_t *p;
2670
2671         for_each_domain(this_cpu, tmp)
2672                 if (tmp->flags & SD_SHARE_CPUPOWER)
2673                         sd = tmp;
2674
2675         if (!sd)
2676                 return 0;
2677
2678         /*
2679          * The same locking rules and details apply as for
2680          * wake_sleeping_dependent():
2681          */
2682         spin_unlock(&this_rq->lock);
2683         sibling_map = sd->span;
2684         for_each_cpu_mask(i, sibling_map)
2685                 spin_lock(&cpu_rq(i)->lock);
2686         cpu_clear(this_cpu, sibling_map);
2687
2688         /*
2689          * Establish next task to be run - it might have gone away because
2690          * we released the runqueue lock above:
2691          */
2692         if (!this_rq->nr_running)
2693                 goto out_unlock;
2694         array = this_rq->active;
2695         if (!array->nr_active)
2696                 array = this_rq->expired;
2697         BUG_ON(!array->nr_active);
2698
2699         p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next,
2700                 task_t, run_list);
2701
2702         for_each_cpu_mask(i, sibling_map) {
2703                 runqueue_t *smt_rq = cpu_rq(i);
2704                 task_t *smt_curr = smt_rq->curr;
2705
2706                 /* Kernel threads do not participate in dependent sleeping */
2707                 if (!p->mm || !smt_curr->mm || rt_task(p))
2708                         goto check_smt_task;
2709
2710                 /*
2711                  * If a user task with lower static priority than the
2712                  * running task on the SMT sibling is trying to schedule,
2713                  * delay it till there is proportionately less timeslice
2714                  * left of the sibling task to prevent a lower priority
2715                  * task from using an unfair proportion of the
2716                  * physical cpu's resources. -ck
2717                  */
2718                 if (rt_task(smt_curr)) {
2719                         /*
2720                          * With real time tasks we run non-rt tasks only
2721                          * per_cpu_gain% of the time.
2722                          */
2723                         if ((jiffies % DEF_TIMESLICE) >
2724                                 (sd->per_cpu_gain * DEF_TIMESLICE / 100))
2725                                         ret = 1;
2726                 } else
2727                         if (smt_curr->static_prio < p->static_prio &&
2728                                 !TASK_PREEMPTS_CURR(p, smt_rq) &&
2729                                 smt_slice(smt_curr, sd) > task_timeslice(p))
2730                                         ret = 1;
2731
2732 check_smt_task:
2733                 if ((!smt_curr->mm && smt_curr != smt_rq->idle) ||
2734                         rt_task(smt_curr))
2735                                 continue;
2736                 if (!p->mm) {
2737                         wakeup_busy_runqueue(smt_rq);
2738                         continue;
2739                 }
2740
2741                 /*
2742                  * Reschedule a lower priority task on the SMT sibling for
2743                  * it to be put to sleep, or wake it up if it has been put to
2744                  * sleep for priority reasons to see if it should run now.
2745                  */
2746                 if (rt_task(p)) {
2747                         if ((jiffies % DEF_TIMESLICE) >
2748                                 (sd->per_cpu_gain * DEF_TIMESLICE / 100))
2749                                         resched_task(smt_curr);
2750                 } else {
2751                         if (TASK_PREEMPTS_CURR(p, smt_rq) &&
2752                                 smt_slice(p, sd) > task_timeslice(smt_curr))
2753                                         resched_task(smt_curr);
2754                         else
2755                                 wakeup_busy_runqueue(smt_rq);
2756                 }
2757         }
2758 out_unlock:
2759         for_each_cpu_mask(i, sibling_map)
2760                 spin_unlock(&cpu_rq(i)->lock);
2761         return ret;
2762 }
2763 #else
2764 static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
2765 {
2766 }
2767
2768 static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
2769 {
2770         return 0;
2771 }
2772 #endif
2773
2774 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
2775
2776 void fastcall add_preempt_count(int val)
2777 {
2778         /*
2779          * Underflow?
2780          */
2781         BUG_ON((preempt_count() < 0));
2782         preempt_count() += val;
2783         /*
2784          * Spinlock count overflowing soon?
2785          */
2786         BUG_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10);
2787 }
2788 EXPORT_SYMBOL(add_preempt_count);
2789
2790 void fastcall sub_preempt_count(int val)
2791 {
2792         /*
2793          * Underflow?
2794          */
2795         BUG_ON(val > preempt_count());
2796         /*
2797          * Is the spinlock portion underflowing?
2798          */
2799         BUG_ON((val < PREEMPT_MASK) && !(preempt_count() & PREEMPT_MASK));
2800         preempt_count() -= val;
2801 }
2802 EXPORT_SYMBOL(sub_preempt_count);
2803
2804 #endif
2805
2806 /*
2807  * schedule() is the main scheduler function.
2808  */
2809 asmlinkage void __sched schedule(void)
2810 {
2811         long *switch_count;
2812         task_t *prev, *next;
2813         runqueue_t *rq;
2814         prio_array_t *array;
2815         struct list_head *queue;
2816         unsigned long long now;
2817         unsigned long run_time;
2818         int cpu, idx, new_prio;
2819
2820         /*
2821          * Test if we are atomic.  Since do_exit() needs to call into
2822          * schedule() atomically, we ignore that path for now.
2823          * Otherwise, whine if we are scheduling when we should not be.
2824          */
2825         if (likely(!current->exit_state)) {
2826                 if (unlikely(in_atomic())) {
2827                         printk(KERN_ERR "scheduling while atomic: "
2828                                 "%s/0x%08x/%d\n",
2829                                 current->comm, preempt_count(), current->pid);
2830                         dump_stack();
2831                 }
2832         }
2833         profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2834
2835 need_resched:
2836         preempt_disable();
2837         prev = current;
2838         release_kernel_lock(prev);
2839 need_resched_nonpreemptible:
2840         rq = this_rq();
2841
2842         /*
2843          * The idle thread is not allowed to schedule!
2844          * Remove this check after it has been exercised a bit.
2845          */
2846         if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) {
2847                 printk(KERN_ERR "bad: scheduling from the idle thread!\n");
2848                 dump_stack();
2849         }
2850
2851         schedstat_inc(rq, sched_cnt);
2852         now = sched_clock();
2853         if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) {
2854                 run_time = now - prev->timestamp;
2855                 if (unlikely((long long)(now - prev->timestamp) < 0))
2856                         run_time = 0;
2857         } else
2858                 run_time = NS_MAX_SLEEP_AVG;
2859
2860         /*
2861          * Tasks charged proportionately less run_time at high sleep_avg to
2862          * delay them losing their interactive status
2863          */
2864         run_time /= (CURRENT_BONUS(prev) ? : 1);
2865
2866         spin_lock_irq(&rq->lock);
2867
2868         if (unlikely(prev->flags & PF_DEAD))
2869                 prev->state = EXIT_DEAD;
2870
2871         switch_count = &prev->nivcsw;
2872         if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2873                 switch_count = &prev->nvcsw;
2874                 if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
2875                                 unlikely(signal_pending(prev))))
2876                         prev->state = TASK_RUNNING;
2877                 else {
2878                         if (prev->state == TASK_UNINTERRUPTIBLE)
2879                                 rq->nr_uninterruptible++;
2880                         deactivate_task(prev, rq);
2881                 }
2882         }
2883
2884         cpu = smp_processor_id();
2885         if (unlikely(!rq->nr_running)) {
2886 go_idle:
2887                 idle_balance(cpu, rq);
2888                 if (!rq->nr_running) {
2889                         next = rq->idle;
2890                         rq->expired_timestamp = 0;
2891                         wake_sleeping_dependent(cpu, rq);
2892                         /*
2893                          * wake_sleeping_dependent() might have released
2894                          * the runqueue, so break out if we got new
2895                          * tasks meanwhile:
2896                          */
2897                         if (!rq->nr_running)
2898                                 goto switch_tasks;
2899                 }
2900         } else {
2901                 if (dependent_sleeper(cpu, rq)) {
2902                         next = rq->idle;
2903                         goto switch_tasks;
2904                 }
2905                 /*
2906                  * dependent_sleeper() releases and reacquires the runqueue
2907                  * lock, hence go into the idle loop if the rq went
2908                  * empty meanwhile:
2909                  */
2910                 if (unlikely(!rq->nr_running))
2911                         goto go_idle;
2912         }
2913
2914         array = rq->active;
2915         if (unlikely(!array->nr_active)) {
2916                 /*
2917                  * Switch the active and expired arrays.
2918                  */
2919                 schedstat_inc(rq, sched_switch);
2920                 rq->active = rq->expired;
2921                 rq->expired = array;
2922                 array = rq->active;
2923                 rq->expired_timestamp = 0;
2924                 rq->best_expired_prio = MAX_PRIO;
2925         }
2926
2927         idx = sched_find_first_bit(array->bitmap);
2928         queue = array->queue + idx;
2929         next = list_entry(queue->next, task_t, run_list);
2930
2931         if (!rt_task(next) && next->activated > 0) {
2932                 unsigned long long delta = now - next->timestamp;
2933                 if (unlikely((long long)(now - next->timestamp) < 0))
2934                         delta = 0;
2935
2936                 if (next->activated == 1)
2937                         delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128;
2938
2939                 array = next->array;
2940                 new_prio = recalc_task_prio(next, next->timestamp + delta);
2941
2942                 if (unlikely(next->prio != new_prio)) {
2943                         dequeue_task(next, array);
2944                         next->prio = new_prio;
2945                         enqueue_task(next, array);
2946                 } else
2947                         requeue_task(next, array);
2948         }
2949         next->activated = 0;
2950 switch_tasks:
2951         if (next == rq->idle)
2952                 schedstat_inc(rq, sched_goidle);
2953         prefetch(next);
2954         prefetch_stack(next);
2955         clear_tsk_need_resched(prev);
2956         rcu_qsctr_inc(task_cpu(prev));
2957
2958         update_cpu_clock(prev, rq, now);
2959
2960         prev->sleep_avg -= run_time;
2961         if ((long)prev->sleep_avg <= 0)
2962                 prev->sleep_avg = 0;
2963         prev->timestamp = prev->last_ran = now;
2964
2965         sched_info_switch(prev, next);
2966         if (likely(prev != next)) {
2967                 next->timestamp = now;
2968                 rq->nr_switches++;
2969                 rq->curr = next;
2970                 ++*switch_count;
2971
2972                 prepare_task_switch(rq, next);
2973                 prev = context_switch(rq, prev, next);
2974                 barrier();
2975                 /*
2976                  * this_rq must be evaluated again because prev may have moved
2977                  * CPUs since it called schedule(), thus the 'rq' on its stack
2978                  * frame will be invalid.
2979                  */
2980                 finish_task_switch(this_rq(), prev);
2981         } else
2982                 spin_unlock_irq(&rq->lock);
2983
2984         prev = current;
2985         if (unlikely(reacquire_kernel_lock(prev) < 0))
2986                 goto need_resched_nonpreemptible;
2987         preempt_enable_no_resched();
2988         if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
2989                 goto need_resched;
2990 }
2991
2992 EXPORT_SYMBOL(schedule);
2993
2994 #ifdef CONFIG_PREEMPT
2995 /*
2996  * this is is the entry point to schedule() from in-kernel preemption
2997  * off of preempt_enable.  Kernel preemptions off return from interrupt
2998  * occur there and call schedule directly.
2999  */
3000 asmlinkage void __sched preempt_schedule(void)
3001 {
3002         struct thread_info *ti = current_thread_info();
3003 #ifdef CONFIG_PREEMPT_BKL
3004         struct task_struct *task = current;
3005         int saved_lock_depth;
3006 #endif
3007         /*
3008          * If there is a non-zero preempt_count or interrupts are disabled,
3009          * we do not want to preempt the current task.  Just return..
3010          */
3011         if (unlikely(ti->preempt_count || irqs_disabled()))
3012                 return;
3013
3014 need_resched:
3015         add_preempt_count(PREEMPT_ACTIVE);
3016         /*
3017          * We keep the big kernel semaphore locked, but we
3018          * clear ->lock_depth so that schedule() doesnt
3019          * auto-release the semaphore:
3020          */
3021 #ifdef CONFIG_PREEMPT_BKL
3022         saved_lock_depth = task->lock_depth;
3023         task->lock_depth = -1;
3024 #endif
3025         schedule();
3026 #ifdef CONFIG_PREEMPT_BKL
3027         task->lock_depth = saved_lock_depth;
3028 #endif
3029         sub_preempt_count(PREEMPT_ACTIVE);
3030
3031         /* we could miss a preemption opportunity between schedule and now */
3032         barrier();
3033         if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3034                 goto need_resched;
3035 }
3036
3037 EXPORT_SYMBOL(preempt_schedule);
3038
3039 /*
3040  * this is is the entry point to schedule() from kernel preemption
3041  * off of irq context.
3042  * Note, that this is called and return with irqs disabled. This will
3043  * protect us against recursive calling from irq.
3044  */
3045 asmlinkage void __sched preempt_schedule_irq(void)
3046 {
3047         struct thread_info *ti = current_thread_info();
3048 #ifdef CONFIG_PREEMPT_BKL
3049         struct task_struct *task = current;
3050         int saved_lock_depth;
3051 #endif
3052         /* Catch callers which need to be fixed*/
3053         BUG_ON(ti->preempt_count || !irqs_disabled());
3054
3055 need_resched:
3056         add_preempt_count(PREEMPT_ACTIVE);
3057         /*
3058          * We keep the big kernel semaphore locked, but we
3059          * clear ->lock_depth so that schedule() doesnt
3060          * auto-release the semaphore:
3061          */
3062 #ifdef CONFIG_PREEMPT_BKL
3063         saved_lock_depth = task->lock_depth;
3064         task->lock_depth = -1;
3065 #endif
3066         local_irq_enable();
3067         schedule();
3068         local_irq_disable();
3069 #ifdef CONFIG_PREEMPT_BKL
3070         task->lock_depth = saved_lock_depth;
3071 #endif
3072         sub_preempt_count(PREEMPT_ACTIVE);
3073
3074         /* we could miss a preemption opportunity between schedule and now */
3075         barrier();
3076         if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
3077                 goto need_resched;
3078 }
3079
3080 #endif /* CONFIG_PREEMPT */
3081
3082 int default_wake_function(wait_queue_t *curr, unsigned mode, int sync,
3083                           void *key)
3084 {
3085         task_t *p = curr->private;
3086         return try_to_wake_up(p, mode, sync);
3087 }
3088
3089 EXPORT_SYMBOL(default_wake_function);
3090
3091 /*
3092  * The core wakeup function.  Non-exclusive wakeups (nr_exclusive == 0) just
3093  * wake everything up.  If it's an exclusive wakeup (nr_exclusive == small +ve
3094  * number) then we wake all the non-exclusive tasks and one exclusive task.
3095  *
3096  * There are circumstances in which we can try to wake a task which has already
3097  * started to run but is not in state TASK_RUNNING.  try_to_wake_up() returns
3098  * zero in this (rare) case, and we handle it by continuing to scan the queue.
3099  */
3100 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3101                              int nr_exclusive, int sync, void *key)
3102 {
3103         struct list_head *tmp, *next;
3104
3105         list_for_each_safe(tmp, next, &q->task_list) {
3106                 wait_queue_t *curr;
3107                 unsigned flags;
3108                 curr = list_entry(tmp, wait_queue_t, task_list);
3109                 flags = curr->flags;
3110                 if (curr->func(curr, mode, sync, key) &&
3111                     (flags & WQ_FLAG_EXCLUSIVE) &&
3112                     !--nr_exclusive)
3113                         break;
3114         }
3115 }
3116
3117 /**
3118  * __wake_up - wake up threads blocked on a waitqueue.
3119  * @q: the waitqueue
3120  * @mode: which threads
3121  * @nr_exclusive: how many wake-one or wake-many threads to wake up
3122  * @key: is directly passed to the wakeup function
3123  */
3124 void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode,
3125                         int nr_exclusive, void *key)
3126 {
3127         unsigned long flags;
3128
3129         spin_lock_irqsave(&q->lock, flags);
3130         __wake_up_common(q, mode, nr_exclusive, 0, key);
3131         spin_unlock_irqrestore(&q->lock, flags);
3132 }
3133
3134 EXPORT_SYMBOL(__wake_up);
3135
3136 /*
3137  * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3138  */
3139 void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3140 {
3141         __wake_up_common(q, mode, 1, 0, NULL);
3142 }
3143
3144 /**
3145  * __wake_up_sync - wake up threads blocked on a waitqueue.
3146  * @q: the waitqueue
3147  * @mode: which threads
3148  * @nr_exclusive: how many wake-one or wake-many threads to wake up
3149  *
3150  * The sync wakeup differs that the waker knows that it will schedule
3151  * away soon, so while the target thread will be woken up, it will not
3152  * be migrated to another CPU - ie. the two threads are 'synchronized'
3153  * with each other. This can prevent needless bouncing between CPUs.
3154  *
3155  * On UP it can prevent extra preemption.
3156  */
3157 void fastcall
3158 __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3159 {
3160         unsigned long flags;
3161         int sync = 1;
3162
3163         if (unlikely(!q))
3164                 return;
3165
3166         if (unlikely(!nr_exclusive))
3167                 sync = 0;
3168
3169         spin_lock_irqsave(&q->lock, flags);
3170         __wake_up_common(q, mode, nr_exclusive, sync, NULL);
3171         spin_unlock_irqrestore(&q->lock, flags);
3172 }
3173 EXPORT_SYMBOL_GPL(__wake_up_sync);      /* For internal use only */
3174
3175 void fastcall complete(struct completion *x)
3176 {
3177         unsigned long flags;
3178
3179         spin_lock_irqsave(&x->wait.lock, flags);
3180         x->done++;
3181         __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3182                          1, 0, NULL);
3183         spin_unlock_irqrestore(&x->wait.lock, flags);
3184 }
3185 EXPORT_SYMBOL(complete);
3186
3187 void fastcall complete_all(struct completion *x)
3188 {
3189         unsigned long flags;
3190
3191         spin_lock_irqsave(&x->wait.lock, flags);
3192         x->done += UINT_MAX/2;
3193         __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
3194                          0, 0, NULL);
3195         spin_unlock_irqrestore(&x->wait.lock, flags);
3196 }
3197 EXPORT_SYMBOL(complete_all);
3198
3199 void fastcall __sched wait_for_completion(struct completion *x)
3200 {
3201         might_sleep();
3202         spin_lock_irq(&x->wait.lock);
3203         if (!x->done) {
3204                 DECLARE_WAITQUEUE(wait, current);
3205
3206                 wait.flags |= WQ_FLAG_EXCLUSIVE;
3207                 __add_wait_queue_tail(&x->wait, &wait);
3208                 do {
3209                         __set_current_state(TASK_UNINTERRUPTIBLE);
3210                         spin_unlock_irq(&x->wait.lock);
3211                         schedule();
3212                         spin_lock_irq(&x->wait.lock);
3213                 } while (!x->done);
3214                 __remove_wait_queue(&x->wait, &wait);
3215         }
3216         x->done--;
3217         spin_unlock_irq(&x->wait.lock);
3218 }
3219 EXPORT_SYMBOL(wait_for_completion);
3220
3221 unsigned long fastcall __sched
3222 wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3223 {
3224         might_sleep();
3225
3226         spin_lock_irq(&x->wait.lock);
3227         if (!x->done) {
3228                 DECLARE_WAITQUEUE(wait, current);
3229
3230                 wait.flags |= WQ_FLAG_EXCLUSIVE;
3231                 __add_wait_queue_tail(&x->wait, &wait);
3232                 do {
3233                         __set_current_state(TASK_UNINTERRUPTIBLE);
3234                         spin_unlock_irq(&x->wait.lock);
3235                         timeout = schedule_timeout(timeout);
3236                         spin_lock_irq(&x->wait.lock);
3237                         if (!timeout) {
3238                                 __remove_wait_queue(&x->wait, &wait);
3239                                 goto out;
3240                         }
3241                 } while (!x->done);
3242                 __remove_wait_queue(&x->wait, &wait);
3243         }
3244         x->done--;
3245 out:
3246         spin_unlock_irq(&x->wait.lock);
3247         return timeout;
3248 }
3249 EXPORT_SYMBOL(wait_for_completion_timeout);
3250
3251 int fastcall __sched wait_for_completion_interruptible(struct completion *x)
3252 {
3253         int ret = 0;
3254
3255         might_sleep();
3256
3257         spin_lock_irq(&x->wait.lock);
3258         if (!x->done) {
3259                 DECLARE_WAITQUEUE(wait, current);
3260
3261                 wait.flags |= WQ_FLAG_EXCLUSIVE;
3262                 __add_wait_queue_tail(&x->wait, &wait);
3263                 do {
3264                         if (signal_pending(current)) {
3265                                 ret = -ERESTARTSYS;
3266                                 __remove_wait_queue(&x->wait, &wait);
3267                                 goto out;
3268                         }
3269                         __set_current_state(TASK_INTERRUPTIBLE);
3270                         spin_unlock_irq(&x->wait.lock);
3271                         schedule();
3272                         spin_lock_irq(&x->wait.lock);
3273                 } while (!x->done);
3274                 __remove_wait_queue(&x->wait, &wait);
3275         }
3276         x->done--;
3277 out:
3278         spin_unlock_irq(&x->wait.lock);
3279
3280         return ret;
3281 }
3282 EXPORT_SYMBOL(wait_for_completion_interruptible);
3283
3284 unsigned long fastcall __sched
3285 wait_for_completion_interruptible_timeout(struct completion *x,
3286                                           unsigned long timeout)
3287 {
3288         might_sleep();
3289
3290         spin_lock_irq(&x->wait.lock);
3291         if (!x->done) {
3292                 DECLARE_WAITQUEUE(wait, current);
3293
3294                 wait.flags |= WQ_FLAG_EXCLUSIVE;
3295                 __add_wait_queue_tail(&x->wait, &wait);
3296                 do {
3297                         if (signal_pending(current)) {
3298                                 timeout = -ERESTARTSYS;
3299                                 __remove_wait_queue(&x->wait, &wait);
3300                                 goto out;
3301                         }
3302                         __set_current_state(TASK_INTERRUPTIBLE);
3303                         spin_unlock_irq(&x->wait.lock);
3304                         timeout = schedule_timeout(timeout);
3305                         spin_lock_irq(&x->wait.lock);
3306                         if (!timeout) {
3307                                 __remove_wait_queue(&x->wait, &wait);
3308                                 goto out;
3309                         }
3310                 } while (!x->done);
3311                 __remove_wait_queue(&x->wait, &wait);
3312         }
3313         x->done--;
3314 out:
3315         spin_unlock_irq(&x->wait.lock);
3316         return timeout;
3317 }
3318 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3319
3320
3321 #define SLEEP_ON_VAR                                    \
3322         unsigned long flags;                            \
3323         wait_queue_t wait;                              \
3324         init_waitqueue_entry(&wait, current);
3325
3326 #define SLEEP_ON_HEAD                                   \
3327         spin_lock_irqsave(&q->lock,flags);              \
3328         __add_wait_queue(q, &wait);                     \
3329         spin_unlock(&q->lock);
3330
3331 #define SLEEP_ON_TAIL                                   \
3332         spin_lock_irq(&q->lock);                        \
3333         __remove_wait_queue(q, &wait);                  \
3334         spin_unlock_irqrestore(&q->lock, flags);
3335
3336 void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q)
3337 {
3338         SLEEP_ON_VAR
3339
3340         current->state = TASK_INTERRUPTIBLE;
3341
3342         SLEEP_ON_HEAD
3343         schedule();
3344         SLEEP_ON_TAIL
3345 }
3346
3347 EXPORT_SYMBOL(interruptible_sleep_on);
3348
3349 long fastcall __sched
3350 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3351 {
3352         SLEEP_ON_VAR
3353
3354         current->state = TASK_INTERRUPTIBLE;
3355
3356         SLEEP_ON_HEAD
3357         timeout = schedule_timeout(timeout);
3358         SLEEP_ON_TAIL
3359
3360         return timeout;
3361 }
3362
3363 EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3364
3365 void fastcall __sched sleep_on(wait_queue_head_t *q)
3366 {
3367         SLEEP_ON_VAR
3368
3369         current->state = TASK_UNINTERRUPTIBLE;
3370
3371         SLEEP_ON_HEAD
3372         schedule();
3373         SLEEP_ON_TAIL
3374 }
3375
3376 EXPORT_SYMBOL(sleep_on);
3377
3378 long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3379 {
3380         SLEEP_ON_VAR
3381
3382         current->state = TASK_UNINTERRUPTIBLE;
3383
3384         SLEEP_ON_HEAD
3385         timeout = schedule_timeout(timeout);
3386         SLEEP_ON_TAIL
3387
3388         return timeout;
3389 }
3390
3391 EXPORT_SYMBOL(sleep_on_timeout);
3392
3393 void set_user_nice(task_t *p, long nice)
3394 {
3395         unsigned long flags;
3396         prio_array_t *array;
3397         runqueue_t *rq;
3398         int old_prio, new_prio, delta;
3399
3400         if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3401                 return;
3402         /*
3403          * We have to be careful, if called from sys_setpriority(),
3404          * the task might be in the middle of scheduling on another CPU.
3405          */
3406         rq = task_rq_lock(p, &flags);
3407         /*
3408          * The RT priorities are set via sched_setscheduler(), but we still
3409          * allow the 'normal' nice value to be set - but as expected
3410          * it wont have any effect on scheduling until the task is
3411          * not SCHED_NORMAL:
3412          */
3413         if (rt_task(p)) {
3414                 p->static_prio = NICE_TO_PRIO(nice);
3415                 goto out_unlock;
3416         }
3417         array = p->array;
3418         if (array)
3419                 dequeue_task(p, array);
3420
3421         old_prio = p->prio;
3422         new_prio = NICE_TO_PRIO(nice);
3423         delta = new_prio - old_prio;
3424         p->static_prio = NICE_TO_PRIO(nice);
3425         p->prio += delta;
3426
3427         if (array) {
3428                 enqueue_task(p, array);
3429                 /*
3430                  * If the task increased its priority or is running and
3431                  * lowered its priority, then reschedule its CPU:
3432                  */
3433                 if (delta < 0 || (delta > 0 && task_running(rq, p)))
3434                         resched_task(rq->curr);
3435         }
3436 out_unlock:
3437         task_rq_unlock(rq, &flags);
3438 }
3439
3440 EXPORT_SYMBOL(set_user_nice);
3441
3442 /*
3443  * can_nice - check if a task can reduce its nice value
3444  * @p: task
3445  * @nice: nice value
3446  */
3447 int can_nice(const task_t *p, const int nice)
3448 {
3449         /* convert nice value [19,-20] to rlimit style value [1,40] */
3450         int nice_rlim = 20 - nice;
3451         return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur ||
3452                 capable(CAP_SYS_NICE));
3453 }
3454
3455 #ifdef __ARCH_WANT_SYS_NICE
3456
3457 /*
3458  * sys_nice - change the priority of the current process.
3459  * @increment: priority increment
3460  *
3461  * sys_setpriority is a more generic, but much slower function that
3462  * does similar things.
3463  */
3464 asmlinkage long sys_nice(int increment)
3465 {
3466         int retval;
3467         long nice;
3468
3469         /*
3470          * Setpriority might change our priority at the same moment.
3471          * We don't have to worry. Conceptually one call occurs first
3472          * and we have a single winner.
3473          */
3474         if (increment < -40)
3475                 increment = -40;
3476         if (increment > 40)
3477                 increment = 40;
3478
3479         nice = PRIO_TO_NICE(current->static_prio) + increment;
3480         if (nice < -20)
3481                 nice = -20;
3482         if (nice > 19)
3483                 nice = 19;
3484
3485         if (increment < 0 && !can_nice(current, nice))
3486                 return -EPERM;
3487
3488         retval = security_task_setnice(current, nice);
3489         if (retval)
3490                 return retval;
3491
3492         set_user_nice(current, nice);
3493         return 0;
3494 }
3495
3496 #endif
3497
3498 /**
3499  * task_prio - return the priority value of a given task.
3500  * @p: the task in question.
3501  *
3502  * This is the priority value as seen by users in /proc.
3503  * RT tasks are offset by -200. Normal tasks are centered
3504  * around 0, value goes from -16 to +15.
3505  */
3506 int task_prio(const task_t *p)
3507 {
3508         return p->prio - MAX_RT_PRIO;
3509 }
3510
3511 /**
3512  * task_nice - return the nice value of a given task.
3513  * @p: the task in question.
3514  */
3515 int task_nice(const task_t *p)
3516 {
3517         return TASK_NICE(p);
3518 }
3519 EXPORT_SYMBOL_GPL(task_nice);
3520
3521 /**
3522  * idle_cpu - is a given cpu idle currently?
3523  * @cpu: the processor in question.
3524  */
3525 int idle_cpu(int cpu)
3526 {
3527         return cpu_curr(cpu) == cpu_rq(cpu)->idle;
3528 }
3529
3530 EXPORT_SYMBOL_GPL(idle_cpu);
3531
3532 /**
3533  * idle_task - return the idle task for a given cpu.
3534  * @cpu: the processor in question.
3535  */
3536 task_t *idle_task(int cpu)
3537 {
3538         return cpu_rq(cpu)->idle;
3539 }
3540
3541 /**
3542  * find_process_by_pid - find a process with a matching PID value.
3543  * @pid: the pid in question.
3544  */
3545 static inline task_t *find_process_by_pid(pid_t pid)
3546 {
3547         return pid ? find_task_by_pid(pid) : current;
3548 }
3549
3550 /* Actually do priority change: must hold rq lock. */
3551 static void __setscheduler(struct task_struct *p, int policy, int prio)
3552 {
3553         BUG_ON(p->array);
3554         p->policy = policy;
3555         p->rt_priority = prio;
3556         if (policy != SCHED_NORMAL)
3557                 p->prio = MAX_RT_PRIO-1 - p->rt_priority;
3558         else
3559                 p->prio = p->static_prio;
3560 }
3561
3562 /**
3563  * sched_setscheduler - change the scheduling policy and/or RT priority of
3564  * a thread.
3565  * @p: the task in question.
3566  * @policy: new policy.
3567  * @param: structure containing the new RT priority.
3568  */
3569 int sched_setscheduler(struct task_struct *p, int policy,
3570                        struct sched_param *param)
3571 {
3572         int retval;
3573         int oldprio, oldpolicy = -1;
3574         prio_array_t *array;
3575         unsigned long flags;
3576         runqueue_t *rq;
3577
3578 recheck:
3579         /* double check policy once rq lock held */
3580         if (policy < 0)
3581                 policy = oldpolicy = p->policy;
3582         else if (policy != SCHED_FIFO && policy != SCHED_RR &&
3583                                 policy != SCHED_NORMAL)
3584                         return -EINVAL;
3585         /*
3586          * Valid priorities for SCHED_FIFO and SCHED_RR are
3587          * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL is 0.
3588          */
3589         if (param->sched_priority < 0 ||
3590             (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
3591             (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
3592                 return -EINVAL;
3593         if ((policy == SCHED_NORMAL) != (param->sched_priority == 0))
3594                 return -EINVAL;
3595
3596         /*
3597          * Allow unprivileged RT tasks to decrease priority:
3598          */
3599         if (!capable(CAP_SYS_NICE)) {
3600                 /* can't change policy */
3601                 if (policy != p->policy &&
3602                         !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
3603                         return -EPERM;
3604                 /* can't increase priority */
3605                 if (policy != SCHED_NORMAL &&
3606                     param->sched_priority > p->rt_priority &&
3607                     param->sched_priority >
3608                                 p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
3609                         return -EPERM;
3610                 /* can't change other user's priorities */
3611                 if ((current->euid != p->euid) &&
3612                     (current->euid != p->uid))
3613                         return -EPERM;
3614         }
3615
3616         retval = security_task_setscheduler(p, policy, param);
3617         if (retval)
3618                 return retval;
3619         /*
3620          * To be able to change p->policy safely, the apropriate
3621          * runqueue lock must be held.
3622          */
3623         rq = task_rq_lock(p, &flags);
3624         /* recheck policy now with rq lock held */
3625         if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3626                 policy = oldpolicy = -1;
3627                 task_rq_unlock(rq, &flags);
3628                 goto recheck;
3629         }
3630         array = p->array;
3631         if (array)
3632                 deactivate_task(p, rq);
3633         oldprio = p->prio;
3634         __setscheduler(p, policy, param->sched_priority);
3635         if (array) {
3636                 __activate_task(p, rq);
3637                 /*
3638                  * Reschedule if we are currently running on this runqueue and
3639                  * our priority decreased, or if we are not currently running on
3640                  * this runqueue and our priority is higher than the current's
3641                  */
3642                 if (task_running(rq, p)) {
3643                         if (p->prio > oldprio)
3644                                 resched_task(rq->curr);
3645                 } else if (TASK_PREEMPTS_CURR(p, rq))
3646                         resched_task(rq->curr);
3647         }
3648         task_rq_unlock(rq, &flags);
3649         return 0;
3650 }
3651 EXPORT_SYMBOL_GPL(sched_setscheduler);
3652
3653 static int
3654 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3655 {
3656         int retval;
3657         struct sched_param lparam;
3658         struct task_struct *p;
3659
3660         if (!param || pid < 0)
3661                 return -EINVAL;
3662         if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3663                 return -EFAULT;
3664         read_lock_irq(&tasklist_lock);
3665         p = find_process_by_pid(pid);
3666         if (!p) {
3667                 read_unlock_irq(&tasklist_lock);
3668                 return -ESRCH;
3669         }
3670         retval = sched_setscheduler(p, policy, &lparam);
3671         read_unlock_irq(&tasklist_lock);
3672         return retval;
3673 }
3674
3675 /**
3676  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3677  * @pid: the pid in question.
3678  * @policy: new policy.
3679  * @param: structure containing the new RT priority.
3680  */
3681 asmlinkage long sys_sched_setscheduler(pid_t pid, int policy,
3682                                        struct sched_param __user *param)
3683 {
3684         return do_sched_setscheduler(pid, policy, param);
3685 }
3686
3687 /**
3688  * sys_sched_setparam - set/change the RT priority of a thread
3689  * @pid: the pid in question.
3690  * @param: structure containing the new RT priority.
3691  */
3692 asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param)
3693 {
3694         return do_sched_setscheduler(pid, -1, param);
3695 }
3696
3697 /**
3698  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3699  * @pid: the pid in question.
3700  */
3701 asmlinkage long sys_sched_getscheduler(pid_t pid)
3702 {
3703         int retval = -EINVAL;
3704         task_t *p;
3705
3706         if (pid < 0)
3707                 goto out_nounlock;
3708
3709         retval = -ESRCH;
3710         read_lock(&tasklist_lock);
3711         p = find_process_by_pid(pid);
3712         if (p) {
3713                 retval = security_task_getscheduler(p);
3714                 if (!retval)
3715                         retval = p->policy;
3716         }
3717         read_unlock(&tasklist_lock);
3718
3719 out_nounlock:
3720         return retval;
3721 }
3722
3723 /**
3724  * sys_sched_getscheduler - get the RT priority of a thread
3725  * @pid: the pid in question.
3726  * @param: structure containing the RT priority.
3727  */
3728 asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param)
3729 {
3730         struct sched_param lp;
3731         int retval = -EINVAL;
3732         task_t *p;
3733
3734         if (!param || pid < 0)
3735                 goto out_nounlock;
3736
3737         read_lock(&tasklist_lock);
3738         p = find_process_by_pid(pid);
3739         retval = -ESRCH;
3740         if (!p)
3741                 goto out_unlock;
3742
3743         retval = security_task_getscheduler(p);
3744         if (retval)
3745                 goto out_unlock;
3746
3747         lp.sched_priority = p->rt_priority;
3748         read_unlock(&tasklist_lock);
3749
3750         /*
3751          * This one might sleep, we cannot do it with a spinlock held ...
3752          */
3753         retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3754
3755 out_nounlock:
3756         return retval;
3757
3758 out_unlock:
3759         read_unlock(&tasklist_lock);
3760         return retval;
3761 }
3762
3763 long sched_setaffinity(pid_t pid, cpumask_t new_mask)
3764 {
3765         task_t *p;
3766         int retval;
3767         cpumask_t cpus_allowed;
3768
3769         lock_cpu_hotplug();
3770         read_lock(&tasklist_lock);
3771
3772         p = find_process_by_pid(pid);
3773         if (!p) {
3774                 read_unlock(&tasklist_lock);
3775                 unlock_cpu_hotplug();
3776                 return -ESRCH;
3777         }
3778
3779         /*
3780          * It is not safe to call set_cpus_allowed with the
3781          * tasklist_lock held.  We will bump the task_struct's
3782          * usage count and then drop tasklist_lock.
3783          */
3784         get_task_struct(p);
3785         read_unlock(&tasklist_lock);
3786
3787         retval = -EPERM;
3788         if ((current->euid != p->euid) && (current->euid != p->uid) &&
3789                         !capable(CAP_SYS_NICE))
3790                 goto out_unlock;
3791
3792         cpus_allowed = cpuset_cpus_allowed(p);
3793         cpus_and(new_mask, new_mask, cpus_allowed);
3794         retval = set_cpus_allowed(p, new_mask);
3795
3796 out_unlock:
3797         put_task_struct(p);
3798         unlock_cpu_hotplug();
3799         return retval;
3800 }
3801
3802 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
3803                              cpumask_t *new_mask)
3804 {
3805         if (len < sizeof(cpumask_t)) {
3806                 memset(new_mask, 0, sizeof(cpumask_t));
3807         } else if (len > sizeof(cpumask_t)) {
3808                 len = sizeof(cpumask_t);
3809         }
3810         return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
3811 }
3812
3813 /**
3814  * sys_sched_setaffinity - set the cpu affinity of a process
3815  * @pid: pid of the process
3816  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3817  * @user_mask_ptr: user-space pointer to the new cpu mask
3818  */
3819 asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len,
3820                                       unsigned long __user *user_mask_ptr)
3821 {
3822         cpumask_t new_mask;
3823         int retval;
3824
3825         retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask);
3826         if (retval)
3827                 return retval;
3828
3829         return sched_setaffinity(pid, new_mask);
3830 }
3831
3832 /*
3833  * Represents all cpu's present in the system
3834  * In systems capable of hotplug, this map could dynamically grow
3835  * as new cpu's are detected in the system via any platform specific
3836  * method, such as ACPI for e.g.
3837  */
3838
3839 cpumask_t cpu_present_map;
3840 EXPORT_SYMBOL(cpu_present_map);
3841
3842 #ifndef CONFIG_SMP
3843 cpumask_t cpu_online_map = CPU_MASK_ALL;
3844 cpumask_t cpu_possible_map = CPU_MASK_ALL;
3845 #endif
3846
3847 long sched_getaffinity(pid_t pid, cpumask_t *mask)
3848 {
3849         int retval;
3850         task_t *p;
3851
3852         lock_cpu_hotplug();
3853         read_lock(&tasklist_lock);
3854
3855         retval = -ESRCH;
3856         p = find_process_by_pid(pid);
3857         if (!p)
3858                 goto out_unlock;
3859
3860         retval = 0;
3861         cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
3862
3863 out_unlock:
3864         read_unlock(&tasklist_lock);
3865         unlock_cpu_hotplug();
3866         if (retval)
3867                 return retval;
3868
3869         return 0;
3870 }
3871
3872 /**
3873  * sys_sched_getaffinity - get the cpu affinity of a process
3874  * @pid: pid of the process
3875  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
3876  * @user_mask_ptr: user-space pointer to hold the current cpu mask
3877  */
3878 asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len,
3879                                       unsigned long __user *user_mask_ptr)
3880 {
3881         int ret;
3882         cpumask_t mask;
3883
3884         if (len < sizeof(cpumask_t))
3885                 return -EINVAL;
3886
3887         ret = sched_getaffinity(pid, &mask);
3888         if (ret < 0)
3889                 return ret;
3890
3891         if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t)))
3892                 return -EFAULT;
3893
3894         return sizeof(cpumask_t);
3895 }
3896
3897 /**
3898  * sys_sched_yield - yield the current processor to other threads.
3899  *
3900  * this function yields the current CPU by moving the calling thread
3901  * to the expired array. If there are no other threads running on this
3902  * CPU then this function will return.
3903  */
3904 asmlinkage long sys_sched_yield(void)
3905 {
3906         runqueue_t *rq = this_rq_lock();
3907         prio_array_t *array = current->array;
3908         prio_array_t *target = rq->expired;
3909
3910         schedstat_inc(rq, yld_cnt);
3911         /*
3912          * We implement yielding by moving the task into the expired
3913          * queue.
3914          *
3915          * (special rule: RT tasks will just roundrobin in the active
3916          *  array.)
3917          */
3918         if (rt_task(current))
3919                 target = rq->active;
3920
3921         if (current->array->nr_active == 1) {
3922                 schedstat_inc(rq, yld_act_empty);
3923                 if (!rq->expired->nr_active)
3924                         schedstat_inc(rq, yld_both_empty);
3925         } else if (!