4 * Kernel scheduler and related syscalls
6 * Copyright (C) 1991-2002 Linus Torvalds
8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9 * make semaphores SMP safe
10 * 1998-11-19 Implemented schedule_timeout() and related stuff
12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13 * hybrid priority-list and round-robin design with
14 * an array-switch method of distributing timeslices
15 * and per-CPU runqueues. Cleanups and useful suggestions
16 * by Davide Libenzi, preemptible kernel bits by Robert Love.
17 * 2003-09-03 Interactivity tuning by Con Kolivas.
18 * 2004-04-02 Scheduler domains code by Nick Piggin
22 #include <linux/module.h>
23 #include <linux/nmi.h>
24 #include <linux/init.h>
25 #include <asm/uaccess.h>
26 #include <linux/highmem.h>
27 #include <linux/smp_lock.h>
28 #include <asm/mmu_context.h>
29 #include <linux/interrupt.h>
30 #include <linux/capability.h>
31 #include <linux/completion.h>
32 #include <linux/kernel_stat.h>
33 #include <linux/debug_locks.h>
34 #include <linux/security.h>
35 #include <linux/notifier.h>
36 #include <linux/profile.h>
37 #include <linux/freezer.h>
38 #include <linux/vmalloc.h>
39 #include <linux/blkdev.h>
40 #include <linux/delay.h>
41 #include <linux/smp.h>
42 #include <linux/threads.h>
43 #include <linux/timer.h>
44 #include <linux/rcupdate.h>
45 #include <linux/cpu.h>
46 #include <linux/cpuset.h>
47 #include <linux/percpu.h>
48 #include <linux/kthread.h>
49 #include <linux/seq_file.h>
50 #include <linux/syscalls.h>
51 #include <linux/times.h>
52 #include <linux/tsacct_kern.h>
53 #include <linux/kprobes.h>
54 #include <linux/delayacct.h>
57 #include <asm/unistd.h>
60 * Convert user-nice values [ -20 ... 0 ... 19 ]
61 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
64 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
65 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
66 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
69 * 'User priority' is the nice value converted to something we
70 * can work with better when scaling various scheduler parameters,
71 * it's a [ 0 ... 39 ] range.
73 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
74 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
75 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
78 * Some helpers for converting nanosecond timing to jiffy resolution
80 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
81 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
84 * These are the 'tuning knobs' of the scheduler:
86 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
87 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
88 * Timeslices get refilled after they expire.
90 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
91 #define DEF_TIMESLICE (100 * HZ / 1000)
92 #define ON_RUNQUEUE_WEIGHT 30
93 #define CHILD_PENALTY 95
94 #define PARENT_PENALTY 100
96 #define PRIO_BONUS_RATIO 25
97 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
98 #define INTERACTIVE_DELTA 2
99 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
100 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
101 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
104 * If a task is 'interactive' then we reinsert it in the active
105 * array after it has expired its current timeslice. (it will not
106 * continue to run immediately, it will still roundrobin with
107 * other interactive tasks.)
109 * This part scales the interactivity limit depending on niceness.
111 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
112 * Here are a few examples of different nice levels:
114 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
115 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
116 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
117 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
118 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
120 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
121 * priority range a task can explore, a value of '1' means the
122 * task is rated interactive.)
124 * Ie. nice +19 tasks can never get 'interactive' enough to be
125 * reinserted into the active array. And only heavily CPU-hog nice -20
126 * tasks will be expired. Default nice 0 tasks are somewhere between,
127 * it takes some effort for them to get interactive, but it's not
131 #define CURRENT_BONUS(p) \
132 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
135 #define GRANULARITY (10 * HZ / 1000 ? : 1)
138 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
139 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
142 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
143 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
146 #define SCALE(v1,v1_max,v2_max) \
147 (v1) * (v2_max) / (v1_max)
150 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
153 #define TASK_INTERACTIVE(p) \
154 ((p)->prio <= (p)->static_prio - DELTA(p))
156 #define INTERACTIVE_SLEEP(p) \
157 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
158 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
160 #define TASK_PREEMPTS_CURR(p, rq) \
161 ((p)->prio < (rq)->curr->prio)
163 #define SCALE_PRIO(x, prio) \
164 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
166 static unsigned int static_prio_timeslice(int static_prio
)
168 if (static_prio
< NICE_TO_PRIO(0))
169 return SCALE_PRIO(DEF_TIMESLICE
* 4, static_prio
);
171 return SCALE_PRIO(DEF_TIMESLICE
, static_prio
);
175 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
176 * to time slice values: [800ms ... 100ms ... 5ms]
178 * The higher a thread's priority, the bigger timeslices
179 * it gets during one round of execution. But even the lowest
180 * priority thread gets MIN_TIMESLICE worth of execution time.
183 static inline unsigned int task_timeslice(struct task_struct
*p
)
185 return static_prio_timeslice(p
->static_prio
);
189 * These are the runqueue data structures:
193 unsigned int nr_active
;
194 DECLARE_BITMAP(bitmap
, MAX_PRIO
+1); /* include 1 bit for delimiter */
195 struct list_head queue
[MAX_PRIO
];
199 * This is the main, per-CPU runqueue data structure.
201 * Locking rule: those places that want to lock multiple runqueues
202 * (such as the load balancing or the thread migration code), lock
203 * acquire operations must be ordered by ascending &runqueue.
209 * nr_running and cpu_load should be in the same cacheline because
210 * remote CPUs use both these fields when doing load calculation.
212 unsigned long nr_running
;
213 unsigned long raw_weighted_load
;
215 unsigned long cpu_load
[3];
217 unsigned long long nr_switches
;
220 * This is part of a global counter where only the total sum
221 * over all CPUs matters. A task can increase this counter on
222 * one CPU and if it got migrated afterwards it may decrease
223 * it on another CPU. Always updated under the runqueue lock:
225 unsigned long nr_uninterruptible
;
227 unsigned long expired_timestamp
;
228 /* Cached timestamp set by update_cpu_clock() */
229 unsigned long long most_recent_timestamp
;
230 struct task_struct
*curr
, *idle
;
231 unsigned long next_balance
;
232 struct mm_struct
*prev_mm
;
233 struct prio_array
*active
, *expired
, arrays
[2];
234 int best_expired_prio
;
238 struct sched_domain
*sd
;
240 /* For active balancing */
243 int cpu
; /* cpu of this runqueue */
245 struct task_struct
*migration_thread
;
246 struct list_head migration_queue
;
249 #ifdef CONFIG_SCHEDSTATS
251 struct sched_info rq_sched_info
;
253 /* sys_sched_yield() stats */
254 unsigned long yld_exp_empty
;
255 unsigned long yld_act_empty
;
256 unsigned long yld_both_empty
;
257 unsigned long yld_cnt
;
259 /* schedule() stats */
260 unsigned long sched_switch
;
261 unsigned long sched_cnt
;
262 unsigned long sched_goidle
;
264 /* try_to_wake_up() stats */
265 unsigned long ttwu_cnt
;
266 unsigned long ttwu_local
;
268 struct lock_class_key rq_lock_key
;
271 static DEFINE_PER_CPU(struct rq
, runqueues
);
273 static inline int cpu_of(struct rq
*rq
)
283 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
284 * See detach_destroy_domains: synchronize_sched for details.
286 * The domain tree of any CPU may only be accessed from within
287 * preempt-disabled sections.
289 #define for_each_domain(cpu, __sd) \
290 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
292 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
293 #define this_rq() (&__get_cpu_var(runqueues))
294 #define task_rq(p) cpu_rq(task_cpu(p))
295 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
297 #ifndef prepare_arch_switch
298 # define prepare_arch_switch(next) do { } while (0)
300 #ifndef finish_arch_switch
301 # define finish_arch_switch(prev) do { } while (0)
304 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
305 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
307 return rq
->curr
== p
;
310 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
314 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
316 #ifdef CONFIG_DEBUG_SPINLOCK
317 /* this is a valid case when another task releases the spinlock */
318 rq
->lock
.owner
= current
;
321 * If we are tracking spinlock dependencies then we have to
322 * fix up the runqueue lock - which gets 'carried over' from
325 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
327 spin_unlock_irq(&rq
->lock
);
330 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
331 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
336 return rq
->curr
== p
;
340 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
344 * We can optimise this out completely for !SMP, because the
345 * SMP rebalancing from interrupt is the only thing that cares
350 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
351 spin_unlock_irq(&rq
->lock
);
353 spin_unlock(&rq
->lock
);
357 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
361 * After ->oncpu is cleared, the task can be moved to a different CPU.
362 * We must ensure this doesn't happen until the switch is completely
368 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
372 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
375 * __task_rq_lock - lock the runqueue a given task resides on.
376 * Must be called interrupts disabled.
378 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
385 spin_lock(&rq
->lock
);
386 if (unlikely(rq
!= task_rq(p
))) {
387 spin_unlock(&rq
->lock
);
388 goto repeat_lock_task
;
394 * task_rq_lock - lock the runqueue a given task resides on and disable
395 * interrupts. Note the ordering: we can safely lookup the task_rq without
396 * explicitly disabling preemption.
398 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
404 local_irq_save(*flags
);
406 spin_lock(&rq
->lock
);
407 if (unlikely(rq
!= task_rq(p
))) {
408 spin_unlock_irqrestore(&rq
->lock
, *flags
);
409 goto repeat_lock_task
;
414 static inline void __task_rq_unlock(struct rq
*rq
)
417 spin_unlock(&rq
->lock
);
420 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
423 spin_unlock_irqrestore(&rq
->lock
, *flags
);
426 #ifdef CONFIG_SCHEDSTATS
428 * bump this up when changing the output format or the meaning of an existing
429 * format, so that tools can adapt (or abort)
431 #define SCHEDSTAT_VERSION 14
433 static int show_schedstat(struct seq_file
*seq
, void *v
)
437 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
438 seq_printf(seq
, "timestamp %lu\n", jiffies
);
439 for_each_online_cpu(cpu
) {
440 struct rq
*rq
= cpu_rq(cpu
);
442 struct sched_domain
*sd
;
446 /* runqueue-specific stats */
448 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
449 cpu
, rq
->yld_both_empty
,
450 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
451 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
452 rq
->ttwu_cnt
, rq
->ttwu_local
,
453 rq
->rq_sched_info
.cpu_time
,
454 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
456 seq_printf(seq
, "\n");
459 /* domain-specific stats */
461 for_each_domain(cpu
, sd
) {
462 enum idle_type itype
;
463 char mask_str
[NR_CPUS
];
465 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
466 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
467 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
469 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu "
472 sd
->lb_balanced
[itype
],
473 sd
->lb_failed
[itype
],
474 sd
->lb_imbalance
[itype
],
475 sd
->lb_gained
[itype
],
476 sd
->lb_hot_gained
[itype
],
477 sd
->lb_nobusyq
[itype
],
478 sd
->lb_nobusyg
[itype
]);
480 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu"
482 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
483 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
484 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
485 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
,
486 sd
->ttwu_move_balance
);
494 static int schedstat_open(struct inode
*inode
, struct file
*file
)
496 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
497 char *buf
= kmalloc(size
, GFP_KERNEL
);
503 res
= single_open(file
, show_schedstat
, NULL
);
505 m
= file
->private_data
;
513 const struct file_operations proc_schedstat_operations
= {
514 .open
= schedstat_open
,
517 .release
= single_release
,
521 * Expects runqueue lock to be held for atomicity of update
524 rq_sched_info_arrive(struct rq
*rq
, unsigned long delta_jiffies
)
527 rq
->rq_sched_info
.run_delay
+= delta_jiffies
;
528 rq
->rq_sched_info
.pcnt
++;
533 * Expects runqueue lock to be held for atomicity of update
536 rq_sched_info_depart(struct rq
*rq
, unsigned long delta_jiffies
)
539 rq
->rq_sched_info
.cpu_time
+= delta_jiffies
;
541 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
542 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
543 #else /* !CONFIG_SCHEDSTATS */
545 rq_sched_info_arrive(struct rq
*rq
, unsigned long delta_jiffies
)
548 rq_sched_info_depart(struct rq
*rq
, unsigned long delta_jiffies
)
550 # define schedstat_inc(rq, field) do { } while (0)
551 # define schedstat_add(rq, field, amt) do { } while (0)
555 * this_rq_lock - lock this runqueue and disable interrupts.
557 static inline struct rq
*this_rq_lock(void)
564 spin_lock(&rq
->lock
);
569 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
571 * Called when a process is dequeued from the active array and given
572 * the cpu. We should note that with the exception of interactive
573 * tasks, the expired queue will become the active queue after the active
574 * queue is empty, without explicitly dequeuing and requeuing tasks in the
575 * expired queue. (Interactive tasks may be requeued directly to the
576 * active queue, thus delaying tasks in the expired queue from running;
577 * see scheduler_tick()).
579 * This function is only called from sched_info_arrive(), rather than
580 * dequeue_task(). Even though a task may be queued and dequeued multiple
581 * times as it is shuffled about, we're really interested in knowing how
582 * long it was from the *first* time it was queued to the time that it
585 static inline void sched_info_dequeued(struct task_struct
*t
)
587 t
->sched_info
.last_queued
= 0;
591 * Called when a task finally hits the cpu. We can now calculate how
592 * long it was waiting to run. We also note when it began so that we
593 * can keep stats on how long its timeslice is.
595 static void sched_info_arrive(struct task_struct
*t
)
597 unsigned long now
= jiffies
, delta_jiffies
= 0;
599 if (t
->sched_info
.last_queued
)
600 delta_jiffies
= now
- t
->sched_info
.last_queued
;
601 sched_info_dequeued(t
);
602 t
->sched_info
.run_delay
+= delta_jiffies
;
603 t
->sched_info
.last_arrival
= now
;
604 t
->sched_info
.pcnt
++;
606 rq_sched_info_arrive(task_rq(t
), delta_jiffies
);
610 * Called when a process is queued into either the active or expired
611 * array. The time is noted and later used to determine how long we
612 * had to wait for us to reach the cpu. Since the expired queue will
613 * become the active queue after active queue is empty, without dequeuing
614 * and requeuing any tasks, we are interested in queuing to either. It
615 * is unusual but not impossible for tasks to be dequeued and immediately
616 * requeued in the same or another array: this can happen in sched_yield(),
617 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
620 * This function is only called from enqueue_task(), but also only updates
621 * the timestamp if it is already not set. It's assumed that
622 * sched_info_dequeued() will clear that stamp when appropriate.
624 static inline void sched_info_queued(struct task_struct
*t
)
626 if (unlikely(sched_info_on()))
627 if (!t
->sched_info
.last_queued
)
628 t
->sched_info
.last_queued
= jiffies
;
632 * Called when a process ceases being the active-running process, either
633 * voluntarily or involuntarily. Now we can calculate how long we ran.
635 static inline void sched_info_depart(struct task_struct
*t
)
637 unsigned long delta_jiffies
= jiffies
- t
->sched_info
.last_arrival
;
639 t
->sched_info
.cpu_time
+= delta_jiffies
;
640 rq_sched_info_depart(task_rq(t
), delta_jiffies
);
644 * Called when tasks are switched involuntarily due, typically, to expiring
645 * their time slice. (This may also be called when switching to or from
646 * the idle task.) We are only called when prev != next.
649 __sched_info_switch(struct task_struct
*prev
, struct task_struct
*next
)
651 struct rq
*rq
= task_rq(prev
);
654 * prev now departs the cpu. It's not interesting to record
655 * stats about how efficient we were at scheduling the idle
658 if (prev
!= rq
->idle
)
659 sched_info_depart(prev
);
661 if (next
!= rq
->idle
)
662 sched_info_arrive(next
);
665 sched_info_switch(struct task_struct
*prev
, struct task_struct
*next
)
667 if (unlikely(sched_info_on()))
668 __sched_info_switch(prev
, next
);
671 #define sched_info_queued(t) do { } while (0)
672 #define sched_info_switch(t, next) do { } while (0)
673 #endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
676 * Adding/removing a task to/from a priority array:
678 static void dequeue_task(struct task_struct
*p
, struct prio_array
*array
)
681 list_del(&p
->run_list
);
682 if (list_empty(array
->queue
+ p
->prio
))
683 __clear_bit(p
->prio
, array
->bitmap
);
686 static void enqueue_task(struct task_struct
*p
, struct prio_array
*array
)
688 sched_info_queued(p
);
689 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
690 __set_bit(p
->prio
, array
->bitmap
);
696 * Put task to the end of the run list without the overhead of dequeue
697 * followed by enqueue.
699 static void requeue_task(struct task_struct
*p
, struct prio_array
*array
)
701 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
705 enqueue_task_head(struct task_struct
*p
, struct prio_array
*array
)
707 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
708 __set_bit(p
->prio
, array
->bitmap
);
714 * __normal_prio - return the priority that is based on the static
715 * priority but is modified by bonuses/penalties.
717 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
718 * into the -5 ... 0 ... +5 bonus/penalty range.
720 * We use 25% of the full 0...39 priority range so that:
722 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
723 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
725 * Both properties are important to certain workloads.
728 static inline int __normal_prio(struct task_struct
*p
)
732 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
734 prio
= p
->static_prio
- bonus
;
735 if (prio
< MAX_RT_PRIO
)
737 if (prio
> MAX_PRIO
-1)
743 * To aid in avoiding the subversion of "niceness" due to uneven distribution
744 * of tasks with abnormal "nice" values across CPUs the contribution that
745 * each task makes to its run queue's load is weighted according to its
746 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
747 * scaled version of the new time slice allocation that they receive on time
752 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
753 * If static_prio_timeslice() is ever changed to break this assumption then
754 * this code will need modification
756 #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
757 #define LOAD_WEIGHT(lp) \
758 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
759 #define PRIO_TO_LOAD_WEIGHT(prio) \
760 LOAD_WEIGHT(static_prio_timeslice(prio))
761 #define RTPRIO_TO_LOAD_WEIGHT(rp) \
762 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
764 static void set_load_weight(struct task_struct
*p
)
766 if (has_rt_policy(p
)) {
768 if (p
== task_rq(p
)->migration_thread
)
770 * The migration thread does the actual balancing.
771 * Giving its load any weight will skew balancing
777 p
->load_weight
= RTPRIO_TO_LOAD_WEIGHT(p
->rt_priority
);
779 p
->load_weight
= PRIO_TO_LOAD_WEIGHT(p
->static_prio
);
783 inc_raw_weighted_load(struct rq
*rq
, const struct task_struct
*p
)
785 rq
->raw_weighted_load
+= p
->load_weight
;
789 dec_raw_weighted_load(struct rq
*rq
, const struct task_struct
*p
)
791 rq
->raw_weighted_load
-= p
->load_weight
;
794 static inline void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
797 inc_raw_weighted_load(rq
, p
);
800 static inline void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
803 dec_raw_weighted_load(rq
, p
);
807 * Calculate the expected normal priority: i.e. priority
808 * without taking RT-inheritance into account. Might be
809 * boosted by interactivity modifiers. Changes upon fork,
810 * setprio syscalls, and whenever the interactivity
811 * estimator recalculates.
813 static inline int normal_prio(struct task_struct
*p
)
817 if (has_rt_policy(p
))
818 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
820 prio
= __normal_prio(p
);
825 * Calculate the current priority, i.e. the priority
826 * taken into account by the scheduler. This value might
827 * be boosted by RT tasks, or might be boosted by
828 * interactivity modifiers. Will be RT if the task got
829 * RT-boosted. If not then it returns p->normal_prio.
831 static int effective_prio(struct task_struct
*p
)
833 p
->normal_prio
= normal_prio(p
);
835 * If we are RT tasks or we were boosted to RT priority,
836 * keep the priority unchanged. Otherwise, update priority
837 * to the normal priority:
839 if (!rt_prio(p
->prio
))
840 return p
->normal_prio
;
845 * __activate_task - move a task to the runqueue.
847 static void __activate_task(struct task_struct
*p
, struct rq
*rq
)
849 struct prio_array
*target
= rq
->active
;
852 target
= rq
->expired
;
853 enqueue_task(p
, target
);
854 inc_nr_running(p
, rq
);
858 * __activate_idle_task - move idle task to the _front_ of runqueue.
860 static inline void __activate_idle_task(struct task_struct
*p
, struct rq
*rq
)
862 enqueue_task_head(p
, rq
->active
);
863 inc_nr_running(p
, rq
);
867 * Recalculate p->normal_prio and p->prio after having slept,
868 * updating the sleep-average too:
870 static int recalc_task_prio(struct task_struct
*p
, unsigned long long now
)
872 /* Caller must always ensure 'now >= p->timestamp' */
873 unsigned long sleep_time
= now
- p
->timestamp
;
878 if (likely(sleep_time
> 0)) {
880 * This ceiling is set to the lowest priority that would allow
881 * a task to be reinserted into the active array on timeslice
884 unsigned long ceiling
= INTERACTIVE_SLEEP(p
);
886 if (p
->mm
&& sleep_time
> ceiling
&& p
->sleep_avg
< ceiling
) {
888 * Prevents user tasks from achieving best priority
889 * with one single large enough sleep.
891 p
->sleep_avg
= ceiling
;
893 * Using INTERACTIVE_SLEEP() as a ceiling places a
894 * nice(0) task 1ms sleep away from promotion, and
895 * gives it 700ms to round-robin with no chance of
896 * being demoted. This is more than generous, so
897 * mark this sleep as non-interactive to prevent the
898 * on-runqueue bonus logic from intervening should
899 * this task not receive cpu immediately.
901 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
904 * Tasks waking from uninterruptible sleep are
905 * limited in their sleep_avg rise as they
906 * are likely to be waiting on I/O
908 if (p
->sleep_type
== SLEEP_NONINTERACTIVE
&& p
->mm
) {
909 if (p
->sleep_avg
>= ceiling
)
911 else if (p
->sleep_avg
+ sleep_time
>=
913 p
->sleep_avg
= ceiling
;
919 * This code gives a bonus to interactive tasks.
921 * The boost works by updating the 'average sleep time'
922 * value here, based on ->timestamp. The more time a
923 * task spends sleeping, the higher the average gets -
924 * and the higher the priority boost gets as well.
926 p
->sleep_avg
+= sleep_time
;
929 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
930 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
933 return effective_prio(p
);
937 * activate_task - move a task to the runqueue and do priority recalculation
939 * Update all the scheduling statistics stuff. (sleep average
940 * calculation, priority modifiers, etc.)
942 static void activate_task(struct task_struct
*p
, struct rq
*rq
, int local
)
944 unsigned long long now
;
952 /* Compensate for drifting sched_clock */
953 struct rq
*this_rq
= this_rq();
954 now
= (now
- this_rq
->most_recent_timestamp
)
955 + rq
->most_recent_timestamp
;
960 * Sleep time is in units of nanosecs, so shift by 20 to get a
961 * milliseconds-range estimation of the amount of time that the task
964 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
965 if (p
->state
== TASK_UNINTERRUPTIBLE
)
966 profile_hits(SLEEP_PROFILING
, (void *)get_wchan(p
),
967 (now
- p
->timestamp
) >> 20);
970 p
->prio
= recalc_task_prio(p
, now
);
973 * This checks to make sure it's not an uninterruptible task
974 * that is now waking up.
976 if (p
->sleep_type
== SLEEP_NORMAL
) {
978 * Tasks which were woken up by interrupts (ie. hw events)
979 * are most likely of interactive nature. So we give them
980 * the credit of extending their sleep time to the period
981 * of time they spend on the runqueue, waiting for execution
982 * on a CPU, first time around:
985 p
->sleep_type
= SLEEP_INTERRUPTED
;
988 * Normal first-time wakeups get a credit too for
989 * on-runqueue time, but it will be weighted down:
991 p
->sleep_type
= SLEEP_INTERACTIVE
;
996 __activate_task(p
, rq
);
1000 * deactivate_task - remove a task from the runqueue.
1002 static void deactivate_task(struct task_struct
*p
, struct rq
*rq
)
1004 dec_nr_running(p
, rq
);
1005 dequeue_task(p
, p
->array
);
1010 * resched_task - mark a task 'to be rescheduled now'.
1012 * On UP this means the setting of the need_resched flag, on SMP it
1013 * might also involve a cross-CPU call to trigger the scheduler on
1018 #ifndef tsk_is_polling
1019 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1022 static void resched_task(struct task_struct
*p
)
1026 assert_spin_locked(&task_rq(p
)->lock
);
1028 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
1031 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
1034 if (cpu
== smp_processor_id())
1037 /* NEED_RESCHED must be visible before we test polling */
1039 if (!tsk_is_polling(p
))
1040 smp_send_reschedule(cpu
);
1043 static inline void resched_task(struct task_struct
*p
)
1045 assert_spin_locked(&task_rq(p
)->lock
);
1046 set_tsk_need_resched(p
);
1051 * task_curr - is this task currently executing on a CPU?
1052 * @p: the task in question.
1054 inline int task_curr(const struct task_struct
*p
)
1056 return cpu_curr(task_cpu(p
)) == p
;
1059 /* Used instead of source_load when we know the type == 0 */
1060 unsigned long weighted_cpuload(const int cpu
)
1062 return cpu_rq(cpu
)->raw_weighted_load
;
1066 struct migration_req
{
1067 struct list_head list
;
1069 struct task_struct
*task
;
1072 struct completion done
;
1076 * The task's runqueue lock must be held.
1077 * Returns true if you have to wait for migration thread.
1080 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1082 struct rq
*rq
= task_rq(p
);
1085 * If the task is not on a runqueue (and not running), then
1086 * it is sufficient to simply update the task's cpu field.
1088 if (!p
->array
&& !task_running(rq
, p
)) {
1089 set_task_cpu(p
, dest_cpu
);
1093 init_completion(&req
->done
);
1095 req
->dest_cpu
= dest_cpu
;
1096 list_add(&req
->list
, &rq
->migration_queue
);
1102 * wait_task_inactive - wait for a thread to unschedule.
1104 * The caller must ensure that the task *will* unschedule sometime soon,
1105 * else this function might spin for a *long* time. This function can't
1106 * be called with interrupts off, or it may introduce deadlock with
1107 * smp_call_function() if an IPI is sent by the same process we are
1108 * waiting to become inactive.
1110 void wait_task_inactive(struct task_struct
*p
)
1112 unsigned long flags
;
1117 rq
= task_rq_lock(p
, &flags
);
1118 /* Must be off runqueue entirely, not preempted. */
1119 if (unlikely(p
->array
|| task_running(rq
, p
))) {
1120 /* If it's preempted, we yield. It could be a while. */
1121 preempted
= !task_running(rq
, p
);
1122 task_rq_unlock(rq
, &flags
);
1128 task_rq_unlock(rq
, &flags
);
1132 * kick_process - kick a running thread to enter/exit the kernel
1133 * @p: the to-be-kicked thread
1135 * Cause a process which is running on another CPU to enter
1136 * kernel-mode, without any delay. (to get signals handled.)
1138 * NOTE: this function doesnt have to take the runqueue lock,
1139 * because all it wants to ensure is that the remote task enters
1140 * the kernel. If the IPI races and the task has been migrated
1141 * to another CPU then no harm is done and the purpose has been
1144 void kick_process(struct task_struct
*p
)
1150 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1151 smp_send_reschedule(cpu
);
1156 * Return a low guess at the load of a migration-source cpu weighted
1157 * according to the scheduling class and "nice" value.
1159 * We want to under-estimate the load of migration sources, to
1160 * balance conservatively.
1162 static inline unsigned long source_load(int cpu
, int type
)
1164 struct rq
*rq
= cpu_rq(cpu
);
1167 return rq
->raw_weighted_load
;
1169 return min(rq
->cpu_load
[type
-1], rq
->raw_weighted_load
);
1173 * Return a high guess at the load of a migration-target cpu weighted
1174 * according to the scheduling class and "nice" value.
1176 static inline unsigned long target_load(int cpu
, int type
)
1178 struct rq
*rq
= cpu_rq(cpu
);
1181 return rq
->raw_weighted_load
;
1183 return max(rq
->cpu_load
[type
-1], rq
->raw_weighted_load
);
1187 * Return the average load per task on the cpu's run queue
1189 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1191 struct rq
*rq
= cpu_rq(cpu
);
1192 unsigned long n
= rq
->nr_running
;
1194 return n
? rq
->raw_weighted_load
/ n
: SCHED_LOAD_SCALE
;
1198 * find_idlest_group finds and returns the least busy CPU group within the
1201 static struct sched_group
*
1202 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1204 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1205 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1206 int load_idx
= sd
->forkexec_idx
;
1207 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1210 unsigned long load
, avg_load
;
1214 /* Skip over this group if it has no CPUs allowed */
1215 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1218 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1220 /* Tally up the load of all CPUs in the group */
1223 for_each_cpu_mask(i
, group
->cpumask
) {
1224 /* Bias balancing toward cpus of our domain */
1226 load
= source_load(i
, load_idx
);
1228 load
= target_load(i
, load_idx
);
1233 /* Adjust by relative CPU power of the group */
1234 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1237 this_load
= avg_load
;
1239 } else if (avg_load
< min_load
) {
1240 min_load
= avg_load
;
1244 group
= group
->next
;
1245 } while (group
!= sd
->groups
);
1247 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1253 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1256 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1259 unsigned long load
, min_load
= ULONG_MAX
;
1263 /* Traverse only the allowed CPUs */
1264 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1266 for_each_cpu_mask(i
, tmp
) {
1267 load
= weighted_cpuload(i
);
1269 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1279 * sched_balance_self: balance the current task (running on cpu) in domains
1280 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1283 * Balance, ie. select the least loaded group.
1285 * Returns the target CPU number, or the same CPU if no balancing is needed.
1287 * preempt must be disabled.
1289 static int sched_balance_self(int cpu
, int flag
)
1291 struct task_struct
*t
= current
;
1292 struct sched_domain
*tmp
, *sd
= NULL
;
1294 for_each_domain(cpu
, tmp
) {
1296 * If power savings logic is enabled for a domain, stop there.
1298 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1300 if (tmp
->flags
& flag
)
1306 struct sched_group
*group
;
1307 int new_cpu
, weight
;
1309 if (!(sd
->flags
& flag
)) {
1315 group
= find_idlest_group(sd
, t
, cpu
);
1321 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1322 if (new_cpu
== -1 || new_cpu
== cpu
) {
1323 /* Now try balancing at a lower domain level of cpu */
1328 /* Now try balancing at a lower domain level of new_cpu */
1331 weight
= cpus_weight(span
);
1332 for_each_domain(cpu
, tmp
) {
1333 if (weight
<= cpus_weight(tmp
->span
))
1335 if (tmp
->flags
& flag
)
1338 /* while loop will break here if sd == NULL */
1344 #endif /* CONFIG_SMP */
1347 * wake_idle() will wake a task on an idle cpu if task->cpu is
1348 * not idle and an idle cpu is available. The span of cpus to
1349 * search starts with cpus closest then further out as needed,
1350 * so we always favor a closer, idle cpu.
1352 * Returns the CPU we should wake onto.
1354 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1355 static int wake_idle(int cpu
, struct task_struct
*p
)
1358 struct sched_domain
*sd
;
1364 for_each_domain(cpu
, sd
) {
1365 if (sd
->flags
& SD_WAKE_IDLE
) {
1366 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1367 for_each_cpu_mask(i
, tmp
) {
1378 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1385 * try_to_wake_up - wake up a thread
1386 * @p: the to-be-woken-up thread
1387 * @state: the mask of task states that can be woken
1388 * @sync: do a synchronous wakeup?
1390 * Put it on the run-queue if it's not already there. The "current"
1391 * thread is always on the run-queue (except when the actual
1392 * re-schedule is in progress), and as such you're allowed to do
1393 * the simpler "current->state = TASK_RUNNING" to mark yourself
1394 * runnable without the overhead of this.
1396 * returns failure only if the task is already active.
1398 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1400 int cpu
, this_cpu
, success
= 0;
1401 unsigned long flags
;
1405 struct sched_domain
*sd
, *this_sd
= NULL
;
1406 unsigned long load
, this_load
;
1410 rq
= task_rq_lock(p
, &flags
);
1411 old_state
= p
->state
;
1412 if (!(old_state
& state
))
1419 this_cpu
= smp_processor_id();
1422 if (unlikely(task_running(rq
, p
)))
1427 schedstat_inc(rq
, ttwu_cnt
);
1428 if (cpu
== this_cpu
) {
1429 schedstat_inc(rq
, ttwu_local
);
1433 for_each_domain(this_cpu
, sd
) {
1434 if (cpu_isset(cpu
, sd
->span
)) {
1435 schedstat_inc(sd
, ttwu_wake_remote
);
1441 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1445 * Check for affine wakeup and passive balancing possibilities.
1448 int idx
= this_sd
->wake_idx
;
1449 unsigned int imbalance
;
1451 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1453 load
= source_load(cpu
, idx
);
1454 this_load
= target_load(this_cpu
, idx
);
1456 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1458 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1459 unsigned long tl
= this_load
;
1460 unsigned long tl_per_task
;
1462 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1465 * If sync wakeup then subtract the (maximum possible)
1466 * effect of the currently running task from the load
1467 * of the current CPU:
1470 tl
-= current
->load_weight
;
1473 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1474 100*(tl
+ p
->load_weight
) <= imbalance
*load
) {
1476 * This domain has SD_WAKE_AFFINE and
1477 * p is cache cold in this domain, and
1478 * there is no bad imbalance.
1480 schedstat_inc(this_sd
, ttwu_move_affine
);
1486 * Start passive balancing when half the imbalance_pct
1489 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1490 if (imbalance
*this_load
<= 100*load
) {
1491 schedstat_inc(this_sd
, ttwu_move_balance
);
1497 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1499 new_cpu
= wake_idle(new_cpu
, p
);
1500 if (new_cpu
!= cpu
) {
1501 set_task_cpu(p
, new_cpu
);
1502 task_rq_unlock(rq
, &flags
);
1503 /* might preempt at this point */
1504 rq
= task_rq_lock(p
, &flags
);
1505 old_state
= p
->state
;
1506 if (!(old_state
& state
))
1511 this_cpu
= smp_processor_id();
1516 #endif /* CONFIG_SMP */
1517 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1518 rq
->nr_uninterruptible
--;
1520 * Tasks on involuntary sleep don't earn
1521 * sleep_avg beyond just interactive state.
1523 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1527 * Tasks that have marked their sleep as noninteractive get
1528 * woken up with their sleep average not weighted in an
1531 if (old_state
& TASK_NONINTERACTIVE
)
1532 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1535 activate_task(p
, rq
, cpu
== this_cpu
);
1537 * Sync wakeups (i.e. those types of wakeups where the waker
1538 * has indicated that it will leave the CPU in short order)
1539 * don't trigger a preemption, if the woken up task will run on
1540 * this cpu. (in this case the 'I will reschedule' promise of
1541 * the waker guarantees that the freshly woken up task is going
1542 * to be considered on this CPU.)
1544 if (!sync
|| cpu
!= this_cpu
) {
1545 if (TASK_PREEMPTS_CURR(p
, rq
))
1546 resched_task(rq
->curr
);
1551 p
->state
= TASK_RUNNING
;
1553 task_rq_unlock(rq
, &flags
);
1558 int fastcall
wake_up_process(struct task_struct
*p
)
1560 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1561 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1563 EXPORT_SYMBOL(wake_up_process
);
1565 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1567 return try_to_wake_up(p
, state
, 0);
1570 static void task_running_tick(struct rq
*rq
, struct task_struct
*p
);
1572 * Perform scheduler related setup for a newly forked process p.
1573 * p is forked by current.
1575 void fastcall
sched_fork(struct task_struct
*p
, int clone_flags
)
1577 int cpu
= get_cpu();
1580 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1582 set_task_cpu(p
, cpu
);
1585 * We mark the process as running here, but have not actually
1586 * inserted it onto the runqueue yet. This guarantees that
1587 * nobody will actually run it, and a signal or other external
1588 * event cannot wake it up and insert it on the runqueue either.
1590 p
->state
= TASK_RUNNING
;
1593 * Make sure we do not leak PI boosting priority to the child:
1595 p
->prio
= current
->normal_prio
;
1597 INIT_LIST_HEAD(&p
->run_list
);
1599 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1600 if (unlikely(sched_info_on()))
1601 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1603 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1606 #ifdef CONFIG_PREEMPT
1607 /* Want to start with kernel preemption disabled. */
1608 task_thread_info(p
)->preempt_count
= 1;
1611 * Share the timeslice between parent and child, thus the
1612 * total amount of pending timeslices in the system doesn't change,
1613 * resulting in more scheduling fairness.
1615 local_irq_disable();
1616 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1618 * The remainder of the first timeslice might be recovered by
1619 * the parent if the child exits early enough.
1621 p
->first_time_slice
= 1;
1622 current
->time_slice
>>= 1;
1623 p
->timestamp
= sched_clock();
1624 if (unlikely(!current
->time_slice
)) {
1626 * This case is rare, it happens when the parent has only
1627 * a single jiffy left from its timeslice. Taking the
1628 * runqueue lock is not a problem.
1630 current
->time_slice
= 1;
1631 task_running_tick(cpu_rq(cpu
), current
);
1638 * wake_up_new_task - wake up a newly created task for the first time.
1640 * This function will do some initial scheduler statistics housekeeping
1641 * that must be done for every newly created context, then puts the task
1642 * on the runqueue and wakes it.
1644 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1646 struct rq
*rq
, *this_rq
;
1647 unsigned long flags
;
1650 rq
= task_rq_lock(p
, &flags
);
1651 BUG_ON(p
->state
!= TASK_RUNNING
);
1652 this_cpu
= smp_processor_id();
1656 * We decrease the sleep average of forking parents
1657 * and children as well, to keep max-interactive tasks
1658 * from forking tasks that are max-interactive. The parent
1659 * (current) is done further down, under its lock.
1661 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1662 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1664 p
->prio
= effective_prio(p
);
1666 if (likely(cpu
== this_cpu
)) {
1667 if (!(clone_flags
& CLONE_VM
)) {
1669 * The VM isn't cloned, so we're in a good position to
1670 * do child-runs-first in anticipation of an exec. This
1671 * usually avoids a lot of COW overhead.
1673 if (unlikely(!current
->array
))
1674 __activate_task(p
, rq
);
1676 p
->prio
= current
->prio
;
1677 p
->normal_prio
= current
->normal_prio
;
1678 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1679 p
->array
= current
->array
;
1680 p
->array
->nr_active
++;
1681 inc_nr_running(p
, rq
);
1685 /* Run child last */
1686 __activate_task(p
, rq
);
1688 * We skip the following code due to cpu == this_cpu
1690 * task_rq_unlock(rq, &flags);
1691 * this_rq = task_rq_lock(current, &flags);
1695 this_rq
= cpu_rq(this_cpu
);
1698 * Not the local CPU - must adjust timestamp. This should
1699 * get optimised away in the !CONFIG_SMP case.
1701 p
->timestamp
= (p
->timestamp
- this_rq
->most_recent_timestamp
)
1702 + rq
->most_recent_timestamp
;
1703 __activate_task(p
, rq
);
1704 if (TASK_PREEMPTS_CURR(p
, rq
))
1705 resched_task(rq
->curr
);
1708 * Parent and child are on different CPUs, now get the
1709 * parent runqueue to update the parent's ->sleep_avg:
1711 task_rq_unlock(rq
, &flags
);
1712 this_rq
= task_rq_lock(current
, &flags
);
1714 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1715 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1716 task_rq_unlock(this_rq
, &flags
);
1720 * Potentially available exiting-child timeslices are
1721 * retrieved here - this way the parent does not get
1722 * penalized for creating too many threads.
1724 * (this cannot be used to 'generate' timeslices
1725 * artificially, because any timeslice recovered here
1726 * was given away by the parent in the first place.)
1728 void fastcall
sched_exit(struct task_struct
*p
)
1730 unsigned long flags
;
1734 * If the child was a (relative-) CPU hog then decrease
1735 * the sleep_avg of the parent as well.
1737 rq
= task_rq_lock(p
->parent
, &flags
);
1738 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1739 p
->parent
->time_slice
+= p
->time_slice
;
1740 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1741 p
->parent
->time_slice
= task_timeslice(p
);
1743 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1744 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1745 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1747 task_rq_unlock(rq
, &flags
);
1751 * prepare_task_switch - prepare to switch tasks
1752 * @rq: the runqueue preparing to switch
1753 * @next: the task we are going to switch to.
1755 * This is called with the rq lock held and interrupts off. It must
1756 * be paired with a subsequent finish_task_switch after the context
1759 * prepare_task_switch sets up locking and calls architecture specific
1762 static inline void prepare_task_switch(struct rq
*rq
, struct task_struct
*next
)
1764 prepare_lock_switch(rq
, next
);
1765 prepare_arch_switch(next
);
1769 * finish_task_switch - clean up after a task-switch
1770 * @rq: runqueue associated with task-switch
1771 * @prev: the thread we just switched away from.
1773 * finish_task_switch must be called after the context switch, paired
1774 * with a prepare_task_switch call before the context switch.
1775 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1776 * and do any other architecture-specific cleanup actions.
1778 * Note that we may have delayed dropping an mm in context_switch(). If
1779 * so, we finish that here outside of the runqueue lock. (Doing it
1780 * with the lock held can cause deadlocks; see schedule() for
1783 static inline void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1784 __releases(rq
->lock
)
1786 struct mm_struct
*mm
= rq
->prev_mm
;
1792 * A task struct has one reference for the use as "current".
1793 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1794 * schedule one last time. The schedule call will never return, and
1795 * the scheduled task must drop that reference.
1796 * The test for TASK_DEAD must occur while the runqueue locks are
1797 * still held, otherwise prev could be scheduled on another cpu, die
1798 * there before we look at prev->state, and then the reference would
1800 * Manfred Spraul <manfred@colorfullife.com>
1802 prev_state
= prev
->state
;
1803 finish_arch_switch(prev
);
1804 finish_lock_switch(rq
, prev
);
1807 if (unlikely(prev_state
== TASK_DEAD
)) {
1809 * Remove function-return probe instances associated with this
1810 * task and put them back on the free list.
1812 kprobe_flush_task(prev
);
1813 put_task_struct(prev
);
1818 * schedule_tail - first thing a freshly forked thread must call.
1819 * @prev: the thread we just switched away from.
1821 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1822 __releases(rq
->lock
)
1824 struct rq
*rq
= this_rq();
1826 finish_task_switch(rq
, prev
);
1827 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1828 /* In this case, finish_task_switch does not reenable preemption */
1831 if (current
->set_child_tid
)
1832 put_user(current
->pid
, current
->set_child_tid
);
1836 * context_switch - switch to the new MM and the new
1837 * thread's register state.
1839 static inline struct task_struct
*
1840 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1841 struct task_struct
*next
)
1843 struct mm_struct
*mm
= next
->mm
;
1844 struct mm_struct
*oldmm
= prev
->active_mm
;
1847 next
->active_mm
= oldmm
;
1848 atomic_inc(&oldmm
->mm_count
);
1849 enter_lazy_tlb(oldmm
, next
);
1851 switch_mm(oldmm
, mm
, next
);
1854 prev
->active_mm
= NULL
;
1855 WARN_ON(rq
->prev_mm
);
1856 rq
->prev_mm
= oldmm
;
1859 * Since the runqueue lock will be released by the next
1860 * task (which is an invalid locking op but in the case
1861 * of the scheduler it's an obvious special-case), so we
1862 * do an early lockdep release here:
1864 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1865 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1868 /* Here we just switch the register state and the stack. */
1869 switch_to(prev
, next
, prev
);
1875 * nr_running, nr_uninterruptible and nr_context_switches:
1877 * externally visible scheduler statistics: current number of runnable
1878 * threads, current number of uninterruptible-sleeping threads, total
1879 * number of context switches performed since bootup.
1881 unsigned long nr_running(void)
1883 unsigned long i
, sum
= 0;
1885 for_each_online_cpu(i
)
1886 sum
+= cpu_rq(i
)->nr_running
;
1891 unsigned long nr_uninterruptible(void)
1893 unsigned long i
, sum
= 0;
1895 for_each_possible_cpu(i
)
1896 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1899 * Since we read the counters lockless, it might be slightly
1900 * inaccurate. Do not allow it to go below zero though:
1902 if (unlikely((long)sum
< 0))
1908 unsigned long long nr_context_switches(void)
1911 unsigned long long sum
= 0;
1913 for_each_possible_cpu(i
)
1914 sum
+= cpu_rq(i
)->nr_switches
;
1919 unsigned long nr_iowait(void)
1921 unsigned long i
, sum
= 0;
1923 for_each_possible_cpu(i
)
1924 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1929 unsigned long nr_active(void)
1931 unsigned long i
, running
= 0, uninterruptible
= 0;
1933 for_each_online_cpu(i
) {
1934 running
+= cpu_rq(i
)->nr_running
;
1935 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
1938 if (unlikely((long)uninterruptible
< 0))
1939 uninterruptible
= 0;
1941 return running
+ uninterruptible
;
1947 * Is this task likely cache-hot:
1950 task_hot(struct task_struct
*p
, unsigned long long now
, struct sched_domain
*sd
)
1952 return (long long)(now
- p
->last_ran
) < (long long)sd
->cache_hot_time
;
1956 * double_rq_lock - safely lock two runqueues
1958 * Note this does not disable interrupts like task_rq_lock,
1959 * you need to do so manually before calling.
1961 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
1962 __acquires(rq1
->lock
)
1963 __acquires(rq2
->lock
)
1965 BUG_ON(!irqs_disabled());
1967 spin_lock(&rq1
->lock
);
1968 __acquire(rq2
->lock
); /* Fake it out ;) */
1971 spin_lock(&rq1
->lock
);
1972 spin_lock(&rq2
->lock
);
1974 spin_lock(&rq2
->lock
);
1975 spin_lock(&rq1
->lock
);
1981 * double_rq_unlock - safely unlock two runqueues
1983 * Note this does not restore interrupts like task_rq_unlock,
1984 * you need to do so manually after calling.
1986 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
1987 __releases(rq1
->lock
)
1988 __releases(rq2
->lock
)
1990 spin_unlock(&rq1
->lock
);
1992 spin_unlock(&rq2
->lock
);
1994 __release(rq2
->lock
);
1998 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2000 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2001 __releases(this_rq
->lock
)
2002 __acquires(busiest
->lock
)
2003 __acquires(this_rq
->lock
)
2005 if (unlikely(!irqs_disabled())) {
2006 /* printk() doesn't work good under rq->lock */
2007 spin_unlock(&this_rq
->lock
);
2010 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2011 if (busiest
< this_rq
) {
2012 spin_unlock(&this_rq
->lock
);
2013 spin_lock(&busiest
->lock
);
2014 spin_lock(&this_rq
->lock
);
2016 spin_lock(&busiest
->lock
);
2021 * If dest_cpu is allowed for this process, migrate the task to it.
2022 * This is accomplished by forcing the cpu_allowed mask to only
2023 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2024 * the cpu_allowed mask is restored.
2026 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2028 struct migration_req req
;
2029 unsigned long flags
;
2032 rq
= task_rq_lock(p
, &flags
);
2033 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2034 || unlikely(cpu_is_offline(dest_cpu
)))
2037 /* force the process onto the specified CPU */
2038 if (migrate_task(p
, dest_cpu
, &req
)) {
2039 /* Need to wait for migration thread (might exit: take ref). */
2040 struct task_struct
*mt
= rq
->migration_thread
;
2042 get_task_struct(mt
);
2043 task_rq_unlock(rq
, &flags
);
2044 wake_up_process(mt
);
2045 put_task_struct(mt
);
2046 wait_for_completion(&req
.done
);
2051 task_rq_unlock(rq
, &flags
);
2055 * sched_exec - execve() is a valuable balancing opportunity, because at
2056 * this point the task has the smallest effective memory and cache footprint.
2058 void sched_exec(void)
2060 int new_cpu
, this_cpu
= get_cpu();
2061 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2063 if (new_cpu
!= this_cpu
)
2064 sched_migrate_task(current
, new_cpu
);
2068 * pull_task - move a task from a remote runqueue to the local runqueue.
2069 * Both runqueues must be locked.
2071 static void pull_task(struct rq
*src_rq
, struct prio_array
*src_array
,
2072 struct task_struct
*p
, struct rq
*this_rq
,
2073 struct prio_array
*this_array
, int this_cpu
)
2075 dequeue_task(p
, src_array
);
2076 dec_nr_running(p
, src_rq
);
2077 set_task_cpu(p
, this_cpu
);
2078 inc_nr_running(p
, this_rq
);
2079 enqueue_task(p
, this_array
);
2080 p
->timestamp
= (p
->timestamp
- src_rq
->most_recent_timestamp
)
2081 + this_rq
->most_recent_timestamp
;
2083 * Note that idle threads have a prio of MAX_PRIO, for this test
2084 * to be always true for them.
2086 if (TASK_PREEMPTS_CURR(p
, this_rq
))
2087 resched_task(this_rq
->curr
);
2091 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2094 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2095 struct sched_domain
*sd
, enum idle_type idle
,
2099 * We do not migrate tasks that are:
2100 * 1) running (obviously), or
2101 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2102 * 3) are cache-hot on their current CPU.
2104 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
2108 if (task_running(rq
, p
))
2112 * Aggressive migration if:
2113 * 1) task is cache cold, or
2114 * 2) too many balance attempts have failed.
2117 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2118 #ifdef CONFIG_SCHEDSTATS
2119 if (task_hot(p
, rq
->most_recent_timestamp
, sd
))
2120 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2125 if (task_hot(p
, rq
->most_recent_timestamp
, sd
))
2130 #define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
2133 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2134 * load from busiest to this_rq, as part of a balancing operation within
2135 * "domain". Returns the number of tasks moved.
2137 * Called with both runqueues locked.
2139 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2140 unsigned long max_nr_move
, unsigned long max_load_move
,
2141 struct sched_domain
*sd
, enum idle_type idle
,
2144 int idx
, pulled
= 0, pinned
= 0, this_best_prio
, best_prio
,
2145 best_prio_seen
, skip_for_load
;
2146 struct prio_array
*array
, *dst_array
;
2147 struct list_head
*head
, *curr
;
2148 struct task_struct
*tmp
;
2151 if (max_nr_move
== 0 || max_load_move
== 0)
2154 rem_load_move
= max_load_move
;
2156 this_best_prio
= rq_best_prio(this_rq
);
2157 best_prio
= rq_best_prio(busiest
);
2159 * Enable handling of the case where there is more than one task
2160 * with the best priority. If the current running task is one
2161 * of those with prio==best_prio we know it won't be moved
2162 * and therefore it's safe to override the skip (based on load) of
2163 * any task we find with that prio.
2165 best_prio_seen
= best_prio
== busiest
->curr
->prio
;
2168 * We first consider expired tasks. Those will likely not be
2169 * executed in the near future, and they are most likely to
2170 * be cache-cold, thus switching CPUs has the least effect
2173 if (busiest
->expired
->nr_active
) {
2174 array
= busiest
->expired
;
2175 dst_array
= this_rq
->expired
;
2177 array
= busiest
->active
;
2178 dst_array
= this_rq
->active
;
2182 /* Start searching at priority 0: */
2186 idx
= sched_find_first_bit(array
->bitmap
);
2188 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
2189 if (idx
>= MAX_PRIO
) {
2190 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
2191 array
= busiest
->active
;
2192 dst_array
= this_rq
->active
;
2198 head
= array
->queue
+ idx
;
2201 tmp
= list_entry(curr
, struct task_struct
, run_list
);
2206 * To help distribute high priority tasks accross CPUs we don't
2207 * skip a task if it will be the highest priority task (i.e. smallest
2208 * prio value) on its new queue regardless of its load weight
2210 skip_for_load
= tmp
->load_weight
> rem_load_move
;
2211 if (skip_for_load
&& idx
< this_best_prio
)
2212 skip_for_load
= !best_prio_seen
&& idx
== best_prio
;
2213 if (skip_for_load
||
2214 !can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2216 best_prio_seen
|= idx
== best_prio
;
2223 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
2225 rem_load_move
-= tmp
->load_weight
;
2228 * We only want to steal up to the prescribed number of tasks
2229 * and the prescribed amount of weighted load.
2231 if (pulled
< max_nr_move
&& rem_load_move
> 0) {
2232 if (idx
< this_best_prio
)
2233 this_best_prio
= idx
;
2241 * Right now, this is the only place pull_task() is called,
2242 * so we can safely collect pull_task() stats here rather than
2243 * inside pull_task().
2245 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2248 *all_pinned
= pinned
;
2253 * find_busiest_group finds and returns the busiest CPU group within the
2254 * domain. It calculates and returns the amount of weighted load which
2255 * should be moved to restore balance via the imbalance parameter.
2257 static struct sched_group
*
2258 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2259 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
,
2260 cpumask_t
*cpus
, int *balance
)
2262 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2263 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2264 unsigned long max_pull
;
2265 unsigned long busiest_load_per_task
, busiest_nr_running
;
2266 unsigned long this_load_per_task
, this_nr_running
;
2268 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2269 int power_savings_balance
= 1;
2270 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2271 unsigned long min_nr_running
= ULONG_MAX
;
2272 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2275 max_load
= this_load
= total_load
= total_pwr
= 0;
2276 busiest_load_per_task
= busiest_nr_running
= 0;
2277 this_load_per_task
= this_nr_running
= 0;
2278 if (idle
== NOT_IDLE
)
2279 load_idx
= sd
->busy_idx
;
2280 else if (idle
== NEWLY_IDLE
)
2281 load_idx
= sd
->newidle_idx
;
2283 load_idx
= sd
->idle_idx
;
2286 unsigned long load
, group_capacity
;
2289 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2290 unsigned long sum_nr_running
, sum_weighted_load
;
2292 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2295 balance_cpu
= first_cpu(group
->cpumask
);
2297 /* Tally up the load of all CPUs in the group */
2298 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2300 for_each_cpu_mask(i
, group
->cpumask
) {
2303 if (!cpu_isset(i
, *cpus
))
2308 if (*sd_idle
&& !idle_cpu(i
))
2311 /* Bias balancing toward cpus of our domain */
2313 if (idle_cpu(i
) && !first_idle_cpu
) {
2318 load
= target_load(i
, load_idx
);
2320 load
= source_load(i
, load_idx
);
2323 sum_nr_running
+= rq
->nr_running
;
2324 sum_weighted_load
+= rq
->raw_weighted_load
;
2328 * First idle cpu or the first cpu(busiest) in this sched group
2329 * is eligible for doing load balancing at this and above
2332 if (local_group
&& balance_cpu
!= this_cpu
&& balance
) {
2337 total_load
+= avg_load
;
2338 total_pwr
+= group
->cpu_power
;
2340 /* Adjust by relative CPU power of the group */
2341 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2343 group_capacity
= group
->cpu_power
/ SCHED_LOAD_SCALE
;
2346 this_load
= avg_load
;
2348 this_nr_running
= sum_nr_running
;
2349 this_load_per_task
= sum_weighted_load
;
2350 } else if (avg_load
> max_load
&&
2351 sum_nr_running
> group_capacity
) {
2352 max_load
= avg_load
;
2354 busiest_nr_running
= sum_nr_running
;
2355 busiest_load_per_task
= sum_weighted_load
;
2358 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2360 * Busy processors will not participate in power savings
2363 if (idle
== NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2367 * If the local group is idle or completely loaded
2368 * no need to do power savings balance at this domain
2370 if (local_group
&& (this_nr_running
>= group_capacity
||
2372 power_savings_balance
= 0;
2375 * If a group is already running at full capacity or idle,
2376 * don't include that group in power savings calculations
2378 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2383 * Calculate the group which has the least non-idle load.
2384 * This is the group from where we need to pick up the load
2387 if ((sum_nr_running
< min_nr_running
) ||
2388 (sum_nr_running
== min_nr_running
&&
2389 first_cpu(group
->cpumask
) <
2390 first_cpu(group_min
->cpumask
))) {
2392 min_nr_running
= sum_nr_running
;
2393 min_load_per_task
= sum_weighted_load
/
2398 * Calculate the group which is almost near its
2399 * capacity but still has some space to pick up some load
2400 * from other group and save more power
2402 if (sum_nr_running
<= group_capacity
- 1) {
2403 if (sum_nr_running
> leader_nr_running
||
2404 (sum_nr_running
== leader_nr_running
&&
2405 first_cpu(group
->cpumask
) >
2406 first_cpu(group_leader
->cpumask
))) {
2407 group_leader
= group
;
2408 leader_nr_running
= sum_nr_running
;
2413 group
= group
->next
;
2414 } while (group
!= sd
->groups
);
2416 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2419 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2421 if (this_load
>= avg_load
||
2422 100*max_load
<= sd
->imbalance_pct
*this_load
)
2425 busiest_load_per_task
/= busiest_nr_running
;
2427 * We're trying to get all the cpus to the average_load, so we don't
2428 * want to push ourselves above the average load, nor do we wish to
2429 * reduce the max loaded cpu below the average load, as either of these
2430 * actions would just result in more rebalancing later, and ping-pong
2431 * tasks around. Thus we look for the minimum possible imbalance.
2432 * Negative imbalances (*we* are more loaded than anyone else) will
2433 * be counted as no imbalance for these purposes -- we can't fix that
2434 * by pulling tasks to us. Be careful of negative numbers as they'll
2435 * appear as very large values with unsigned longs.
2437 if (max_load
<= busiest_load_per_task
)
2441 * In the presence of smp nice balancing, certain scenarios can have
2442 * max load less than avg load(as we skip the groups at or below
2443 * its cpu_power, while calculating max_load..)
2445 if (max_load
< avg_load
) {
2447 goto small_imbalance
;
2450 /* Don't want to pull so many tasks that a group would go idle */
2451 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2453 /* How much load to actually move to equalise the imbalance */
2454 *imbalance
= min(max_pull
* busiest
->cpu_power
,
2455 (avg_load
- this_load
) * this->cpu_power
)
2459 * if *imbalance is less than the average load per runnable task
2460 * there is no gaurantee that any tasks will be moved so we'll have
2461 * a think about bumping its value to force at least one task to be
2464 if (*imbalance
< busiest_load_per_task
) {
2465 unsigned long tmp
, pwr_now
, pwr_move
;
2469 pwr_move
= pwr_now
= 0;
2471 if (this_nr_running
) {
2472 this_load_per_task
/= this_nr_running
;
2473 if (busiest_load_per_task
> this_load_per_task
)
2476 this_load_per_task
= SCHED_LOAD_SCALE
;
2478 if (max_load
- this_load
>= busiest_load_per_task
* imbn
) {
2479 *imbalance
= busiest_load_per_task
;
2484 * OK, we don't have enough imbalance to justify moving tasks,
2485 * however we may be able to increase total CPU power used by
2489 pwr_now
+= busiest
->cpu_power
*
2490 min(busiest_load_per_task
, max_load
);
2491 pwr_now
+= this->cpu_power
*
2492 min(this_load_per_task
, this_load
);
2493 pwr_now
/= SCHED_LOAD_SCALE
;
2495 /* Amount of load we'd subtract */
2496 tmp
= busiest_load_per_task
* SCHED_LOAD_SCALE
/
2499 pwr_move
+= busiest
->cpu_power
*
2500 min(busiest_load_per_task
, max_load
- tmp
);
2502 /* Amount of load we'd add */
2503 if (max_load
* busiest
->cpu_power
<
2504 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2505 tmp
= max_load
* busiest
->cpu_power
/ this->cpu_power
;
2507 tmp
= busiest_load_per_task
* SCHED_LOAD_SCALE
/
2509 pwr_move
+= this->cpu_power
*
2510 min(this_load_per_task
, this_load
+ tmp
);
2511 pwr_move
/= SCHED_LOAD_SCALE
;
2513 /* Move if we gain throughput */
2514 if (pwr_move
<= pwr_now
)
2517 *imbalance
= busiest_load_per_task
;
2523 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2524 if (idle
== NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2527 if (this == group_leader
&& group_leader
!= group_min
) {
2528 *imbalance
= min_load_per_task
;
2538 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2541 find_busiest_queue(struct sched_group
*group
, enum idle_type idle
,
2542 unsigned long imbalance
, cpumask_t
*cpus
)
2544 struct rq
*busiest
= NULL
, *rq
;
2545 unsigned long max_load
= 0;
2548 for_each_cpu_mask(i
, group
->cpumask
) {
2550 if (!cpu_isset(i
, *cpus
))
2555 if (rq
->nr_running
== 1 && rq
->raw_weighted_load
> imbalance
)
2558 if (rq
->raw_weighted_load
> max_load
) {
2559 max_load
= rq
->raw_weighted_load
;
2568 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2569 * so long as it is large enough.
2571 #define MAX_PINNED_INTERVAL 512
2573 static inline unsigned long minus_1_or_zero(unsigned long n
)
2575 return n
> 0 ? n
- 1 : 0;
2579 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2580 * tasks if there is an imbalance.
2582 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2583 struct sched_domain
*sd
, enum idle_type idle
,
2586 int nr_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2587 struct sched_group
*group
;
2588 unsigned long imbalance
;
2590 cpumask_t cpus
= CPU_MASK_ALL
;
2591 unsigned long flags
;
2594 * When power savings policy is enabled for the parent domain, idle
2595 * sibling can pick up load irrespective of busy siblings. In this case,
2596 * let the state of idle sibling percolate up as IDLE, instead of
2597 * portraying it as NOT_IDLE.
2599 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2600 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2603 schedstat_inc(sd
, lb_cnt
[idle
]);
2606 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2613 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2617 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2619 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2623 BUG_ON(busiest
== this_rq
);
2625 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2628 if (busiest
->nr_running
> 1) {
2630 * Attempt to move tasks. If find_busiest_group has found
2631 * an imbalance but busiest->nr_running <= 1, the group is
2632 * still unbalanced. nr_moved simply stays zero, so it is
2633 * correctly treated as an imbalance.
2635 local_irq_save(flags
);
2636 double_rq_lock(this_rq
, busiest
);
2637 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2638 minus_1_or_zero(busiest
->nr_running
),
2639 imbalance
, sd
, idle
, &all_pinned
);
2640 double_rq_unlock(this_rq
, busiest
);
2641 local_irq_restore(flags
);
2643 /* All tasks on this runqueue were pinned by CPU affinity */
2644 if (unlikely(all_pinned
)) {
2645 cpu_clear(cpu_of(busiest
), cpus
);
2646 if (!cpus_empty(cpus
))
2653 schedstat_inc(sd
, lb_failed
[idle
]);
2654 sd
->nr_balance_failed
++;
2656 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2658 spin_lock_irqsave(&busiest
->lock
, flags
);
2660 /* don't kick the migration_thread, if the curr
2661 * task on busiest cpu can't be moved to this_cpu
2663 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2664 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2666 goto out_one_pinned
;
2669 if (!busiest
->active_balance
) {
2670 busiest
->active_balance
= 1;
2671 busiest
->push_cpu
= this_cpu
;
2674 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2676 wake_up_process(busiest
->migration_thread
);
2679 * We've kicked active balancing, reset the failure
2682 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2685 sd
->nr_balance_failed
= 0;
2687 if (likely(!active_balance
)) {
2688 /* We were unbalanced, so reset the balancing interval */
2689 sd
->balance_interval
= sd
->min_interval
;
2692 * If we've begun active balancing, start to back off. This
2693 * case may not be covered by the all_pinned logic if there
2694 * is only 1 task on the busy runqueue (because we don't call
2697 if (sd
->balance_interval
< sd
->max_interval
)
2698 sd
->balance_interval
*= 2;
2701 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2702 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2707 schedstat_inc(sd
, lb_balanced
[idle
]);
2709 sd
->nr_balance_failed
= 0;
2712 /* tune up the balancing interval */
2713 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2714 (sd
->balance_interval
< sd
->max_interval
))
2715 sd
->balance_interval
*= 2;
2717 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2718 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2724 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2725 * tasks if there is an imbalance.
2727 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2728 * this_rq is locked.
2731 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2733 struct sched_group
*group
;
2734 struct rq
*busiest
= NULL
;
2735 unsigned long imbalance
;
2738 cpumask_t cpus
= CPU_MASK_ALL
;
2741 * When power savings policy is enabled for the parent domain, idle
2742 * sibling can pick up load irrespective of busy siblings. In this case,
2743 * let the state of idle sibling percolate up as IDLE, instead of
2744 * portraying it as NOT_IDLE.
2746 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2747 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2750 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2752 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
,
2753 &sd_idle
, &cpus
, NULL
);
2755 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2759 busiest
= find_busiest_queue(group
, NEWLY_IDLE
, imbalance
,
2762 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2766 BUG_ON(busiest
== this_rq
);
2768 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2771 if (busiest
->nr_running
> 1) {
2772 /* Attempt to move tasks */
2773 double_lock_balance(this_rq
, busiest
);
2774 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2775 minus_1_or_zero(busiest
->nr_running
),
2776 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2777 spin_unlock(&busiest
->lock
);
2780 cpu_clear(cpu_of(busiest
), cpus
);
2781 if (!cpus_empty(cpus
))
2787 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2788 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2789 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2792 sd
->nr_balance_failed
= 0;
2797 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2798 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2799 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2801 sd
->nr_balance_failed
= 0;
2807 * idle_balance is called by schedule() if this_cpu is about to become
2808 * idle. Attempts to pull tasks from other CPUs.
2810 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2812 struct sched_domain
*sd
;
2813 int pulled_task
= 0;
2814 unsigned long next_balance
= jiffies
+ 60 * HZ
;
2816 for_each_domain(this_cpu
, sd
) {
2817 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2818 /* If we've pulled tasks over stop searching: */
2819 pulled_task
= load_balance_newidle(this_cpu
,
2821 if (time_after(next_balance
,
2822 sd
->last_balance
+ sd
->balance_interval
))
2823 next_balance
= sd
->last_balance
2824 + sd
->balance_interval
;
2831 * We are going idle. next_balance may be set based on
2832 * a busy processor. So reset next_balance.
2834 this_rq
->next_balance
= next_balance
;
2838 * active_load_balance is run by migration threads. It pushes running tasks
2839 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2840 * running on each physical CPU where possible, and avoids physical /
2841 * logical imbalances.
2843 * Called with busiest_rq locked.
2845 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
2847 int target_cpu
= busiest_rq
->push_cpu
;
2848 struct sched_domain
*sd
;
2849 struct rq
*target_rq
;
2851 /* Is there any task to move? */
2852 if (busiest_rq
->nr_running
<= 1)
2855 target_rq
= cpu_rq(target_cpu
);
2858 * This condition is "impossible", if it occurs
2859 * we need to fix it. Originally reported by
2860 * Bjorn Helgaas on a 128-cpu setup.
2862 BUG_ON(busiest_rq
== target_rq
);
2864 /* move a task from busiest_rq to target_rq */
2865 double_lock_balance(busiest_rq
, target_rq
);
2867 /* Search for an sd spanning us and the target CPU. */
2868 for_each_domain(target_cpu
, sd
) {
2869 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2870 cpu_isset(busiest_cpu
, sd
->span
))
2875 schedstat_inc(sd
, alb_cnt
);
2877 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1,
2878 RTPRIO_TO_LOAD_WEIGHT(100), sd
, SCHED_IDLE
,
2880 schedstat_inc(sd
, alb_pushed
);
2882 schedstat_inc(sd
, alb_failed
);
2884 spin_unlock(&target_rq
->lock
);
2887 static void update_load(struct rq
*this_rq
)
2889 unsigned long this_load
;
2892 this_load
= this_rq
->raw_weighted_load
;
2894 /* Update our load: */
2895 for (i
= 0, scale
= 1; i
< 3; i
++, scale
<<= 1) {
2896 unsigned long old_load
, new_load
;
2898 old_load
= this_rq
->cpu_load
[i
];
2899 new_load
= this_load
;
2901 * Round up the averaging division if load is increasing. This
2902 * prevents us from getting stuck on 9 if the load is 10, for
2905 if (new_load
> old_load
)
2906 new_load
+= scale
-1;
2907 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) / scale
;
2912 * run_rebalance_domains is triggered when needed from the scheduler tick.
2914 * It checks each scheduling domain to see if it is due to be balanced,
2915 * and initiates a balancing operation if so.
2917 * Balancing parameters are set up in arch_init_sched_domains.
2919 static DEFINE_SPINLOCK(balancing
);
2921 static void run_rebalance_domains(struct softirq_action
*h
)
2923 int this_cpu
= smp_processor_id(), balance
= 1;
2924 struct rq
*this_rq
= cpu_rq(this_cpu
);
2925 unsigned long interval
;
2926 struct sched_domain
*sd
;
2928 * We are idle if there are no processes running. This
2929 * is valid even if we are the idle process (SMT).
2931 enum idle_type idle
= !this_rq
->nr_running
?
2932 SCHED_IDLE
: NOT_IDLE
;
2933 /* Earliest time when we have to call run_rebalance_domains again */
2934 unsigned long next_balance
= jiffies
+ 60*HZ
;
2936 for_each_domain(this_cpu
, sd
) {
2937 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2940 interval
= sd
->balance_interval
;
2941 if (idle
!= SCHED_IDLE
)
2942 interval
*= sd
->busy_factor
;
2944 /* scale ms to jiffies */
2945 interval
= msecs_to_jiffies(interval
);
2946 if (unlikely(!interval
))
2949 if (sd
->flags
& SD_SERIALIZE
) {
2950 if (!spin_trylock(&balancing
))
2954 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
2955 if (load_balance(this_cpu
, this_rq
, sd
, idle
, &balance
)) {
2957 * We've pulled tasks over so either we're no
2958 * longer idle, or one of our SMT siblings is
2963 sd
->last_balance
= jiffies
;
2965 if (sd
->flags
& SD_SERIALIZE
)
2966 spin_unlock(&balancing
);
2968 if (time_after(next_balance
, sd
->last_balance
+ interval
))
2969 next_balance
= sd
->last_balance
+ interval
;
2972 * Stop the load balance at this level. There is another
2973 * CPU in our sched group which is doing load balancing more
2979 this_rq
->next_balance
= next_balance
;
2983 * on UP we do not need to balance between CPUs:
2985 static inline void idle_balance(int cpu
, struct rq
*rq
)
2990 static inline void wake_priority_sleeper(struct rq
*rq
)
2992 #ifdef CONFIG_SCHED_SMT
2993 if (!rq
->nr_running
)
2996 spin_lock(&rq
->lock
);
2998 * If an SMT sibling task has been put to sleep for priority
2999 * reasons reschedule the idle task to see if it can now run.
3002 resched_task(rq
->idle
);
3003 spin_unlock(&rq
->lock
);
3007 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3009 EXPORT_PER_CPU_SYMBOL(kstat
);
3012 * This is called on clock ticks and on context switches.
3013 * Bank in p->sched_time the ns elapsed since the last tick or switch.
3016 update_cpu_clock(struct task_struct
*p
, struct rq
*rq
, unsigned long long now
)
3018 p
->sched_time
+= now
- p
->last_ran
;
3019 p
->last_ran
= rq
->most_recent_timestamp
= now
;
3023 * Return current->sched_time plus any more ns on the sched_clock
3024 * that have not yet been banked.
3026 unsigned long long current_sched_time(const struct task_struct
*p
)
3028 unsigned long long ns
;
3029 unsigned long flags
;
3031 local_irq_save(flags
);
3032 ns
= p
->sched_time
+ sched_clock() - p
->last_ran
;
3033 local_irq_restore(flags
);
3039 * We place interactive tasks back into the active array, if possible.
3041 * To guarantee that this does not starve expired tasks we ignore the
3042 * interactivity of a task if the first expired task had to wait more
3043 * than a 'reasonable' amount of time. This deadline timeout is
3044 * load-dependent, as the frequency of array switched decreases with
3045 * increasing number of running tasks. We also ignore the interactivity
3046 * if a better static_prio task has expired:
3048 static inline int expired_starving(struct rq
*rq
)
3050 if (rq
->curr
->static_prio
> rq
->best_expired_prio
)
3052 if (!STARVATION_LIMIT
|| !rq
->expired_timestamp
)
3054 if (jiffies
- rq
->expired_timestamp
> STARVATION_LIMIT
* rq
->nr_running
)
3060 * Account user cpu time to a process.
3061 * @p: the process that the cpu time gets accounted to
3062 * @hardirq_offset: the offset to subtract from hardirq_count()
3063 * @cputime: the cpu time spent in user space since the last update
3065 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3067 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3070 p
->utime
= cputime_add(p
->utime
, cputime
);
3072 /* Add user time to cpustat. */
3073 tmp
= cputime_to_cputime64(cputime
);
3074 if (TASK_NICE(p
) > 0)
3075 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3077 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3081 * Account system cpu time to a process.
3082 * @p: the process that the cpu time gets accounted to
3083 * @hardirq_offset: the offset to subtract from hardirq_count()
3084 * @cputime: the cpu time spent in kernel space since the last update
3086 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3089 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3090 struct rq
*rq
= this_rq();
3093 p
->stime
= cputime_add(p
->stime
, cputime
);
3095 /* Add system time to cpustat. */
3096 tmp
= cputime_to_cputime64(cputime
);
3097 if (hardirq_count() - hardirq_offset
)
3098 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3099 else if (softirq_count())
3100 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3101 else if (p
!= rq
->idle
)
3102 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3103 else if (atomic_read(&rq
->nr_iowait
) > 0)
3104 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3106 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3107 /* Account for system time used */
3108 acct_update_integrals(p
);
3112 * Account for involuntary wait time.
3113 * @p: the process from which the cpu time has been stolen
3114 * @steal: the cpu time spent in involuntary wait
3116 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3118 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3119 cputime64_t tmp
= cputime_to_cputime64(steal
);
3120 struct rq
*rq
= this_rq();
3122 if (p
== rq
->idle
) {
3123 p
->stime
= cputime_add(p
->stime
, steal
);
3124 if (atomic_read(&rq
->nr_iowait
) > 0)
3125 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3127 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3129 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3132 static void task_running_tick(struct rq
*rq
, struct task_struct
*p
)
3134 if (p
->array
!= rq
->active
) {
3135 /* Task has expired but was not scheduled yet */
3136 set_tsk_need_resched(p
);
3139 spin_lock(&rq
->lock
);
3141 * The task was running during this tick - update the
3142 * time slice counter. Note: we do not update a thread's
3143 * priority until it either goes to sleep or uses up its
3144 * timeslice. This makes it possible for interactive tasks
3145 * to use up their timeslices at their highest priority levels.
3149 * RR tasks need a special form of timeslice management.
3150 * FIFO tasks have no timeslices.
3152 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
3153 p
->time_slice
= task_timeslice(p
);
3154 p
->first_time_slice
= 0;
3155 set_tsk_need_resched(p
);
3157 /* put it at the end of the queue: */
3158 requeue_task(p
, rq
->active
);
3162 if (!--p
->time_slice
) {
3163 dequeue_task(p
, rq
->active
);
3164 set_tsk_need_resched(p
);
3165 p
->prio
= effective_prio(p
);
3166 p
->time_slice
= task_timeslice(p
);
3167 p
->first_time_slice
= 0;
3169 if (!rq
->expired_timestamp
)
3170 rq
->expired_timestamp
= jiffies
;
3171 if (!TASK_INTERACTIVE(p
) || expired_starving(rq
)) {
3172 enqueue_task(p
, rq
->expired
);
3173 if (p
->static_prio
< rq
->best_expired_prio
)
3174 rq
->best_expired_prio
= p
->static_prio
;
3176 enqueue_task(p
, rq
->active
);
3179 * Prevent a too long timeslice allowing a task to monopolize
3180 * the CPU. We do this by splitting up the timeslice into
3183 * Note: this does not mean the task's timeslices expire or
3184 * get lost in any way, they just might be preempted by
3185 * another task of equal priority. (one with higher
3186 * priority would have preempted this task already.) We
3187 * requeue this task to the end of the list on this priority
3188 * level, which is in essence a round-robin of tasks with
3191 * This only applies to tasks in the interactive
3192 * delta range with at least TIMESLICE_GRANULARITY to requeue.
3194 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
3195 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
3196 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
3197 (p
->array
== rq
->active
)) {
3199 requeue_task(p
, rq
->active
);
3200 set_tsk_need_resched(p
);
3204 spin_unlock(&rq
->lock
);
3208 * This function gets called by the timer code, with HZ frequency.
3209 * We call it with interrupts disabled.
3211 * It also gets called by the fork code, when changing the parent's
3214 void scheduler_tick(void)
3216 unsigned long long now
= sched_clock();
3217 struct task_struct
*p
= current
;
3218 int cpu
= smp_processor_id();
3219 struct rq
*rq
= cpu_rq(cpu
);
3221 update_cpu_clock(p
, rq
, now
);
3224 /* Task on the idle queue */
3225 wake_priority_sleeper(rq
);
3227 task_running_tick(rq
, p
);
3230 if (time_after_eq(jiffies
, rq
->next_balance
))
3231 raise_softirq(SCHED_SOFTIRQ
);
3235 #ifdef CONFIG_SCHED_SMT
3236 static inline void wakeup_busy_runqueue(struct rq
*rq
)
3238 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
3239 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
3240 resched_task(rq
->idle
);
3244 * Called with interrupt disabled and this_rq's runqueue locked.
3246 static void wake_sleeping_dependent(int this_cpu
)
3248 struct sched_domain
*tmp
, *sd
= NULL
;
3251 for_each_domain(this_cpu
, tmp
) {
3252 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
3261 for_each_cpu_mask(i
, sd
->span
) {
3262 struct rq
*smt_rq
= cpu_rq(i
);
3266 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
3269 wakeup_busy_runqueue(smt_rq
);
3270 spin_unlock(&smt_rq
->lock
);
3275 * number of 'lost' timeslices this task wont be able to fully
3276 * utilize, if another task runs on a sibling. This models the
3277 * slowdown effect of other tasks running on siblings:
3279 static inline unsigned long
3280 smt_slice(struct task_struct
*p
, struct sched_domain
*sd
)
3282 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
3286 * To minimise lock contention and not have to drop this_rq's runlock we only
3287 * trylock the sibling runqueues and bypass those runqueues if we fail to
3288 * acquire their lock. As we only trylock the normal locking order does not
3289 * need to be obeyed.
3292 dependent_sleeper(int this_cpu
, struct rq
*this_rq
, struct task_struct
*p
)
3294 struct sched_domain
*tmp
, *sd
= NULL
;
3297 /* kernel/rt threads do not participate in dependent sleeping */
3298 if (!p
->mm
|| rt_task(p
))
3301 for_each_domain(this_cpu
, tmp
) {
3302 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
3311 for_each_cpu_mask(i
, sd
->span
) {
3312 struct task_struct
*smt_curr
;
3319 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
3322 smt_curr
= smt_rq
->curr
;
3328 * If a user task with lower static priority than the
3329 * running task on the SMT sibling is trying to schedule,
3330 * delay it till there is proportionately less timeslice
3331 * left of the sibling task to prevent a lower priority
3332 * task from using an unfair proportion of the
3333 * physical cpu's resources. -ck
3335 if (rt_task(smt_curr
)) {
3337 * With real time tasks we run non-rt tasks only
3338 * per_cpu_gain% of the time.
3340 if ((jiffies
% DEF_TIMESLICE
) >
3341 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
3344 if (smt_curr
->static_prio
< p
->static_prio
&&
3345 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
3346 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
3350 spin_unlock(&smt_rq
->lock
);
3355 static inline void wake_sleeping_dependent(int this_cpu
)
3359 dependent_sleeper(int this_cpu
, struct rq
*this_rq
, struct task_struct
*p
)
3365 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3367 void fastcall
add_preempt_count(int val
)
3372 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3374 preempt_count() += val
;
3376 * Spinlock count overflowing soon?
3378 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3381 EXPORT_SYMBOL(add_preempt_count
);
3383 void fastcall
sub_preempt_count(int val
)
3388 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3391 * Is the spinlock portion underflowing?
3393 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3394 !(preempt_count() & PREEMPT_MASK
)))
3397 preempt_count() -= val
;
3399 EXPORT_SYMBOL(sub_preempt_count
);
3403 static inline int interactive_sleep(enum sleep_type sleep_type
)
3405 return (sleep_type
== SLEEP_INTERACTIVE
||
3406 sleep_type
== SLEEP_INTERRUPTED
);
3410 * schedule() is the main scheduler function.
3412 asmlinkage
void __sched
schedule(void)
3414 struct task_struct
*prev
, *next
;
3415 struct prio_array
*array
;
3416 struct list_head
*queue
;
3417 unsigned long long now
;
3418 unsigned long run_time
;
3419 int cpu
, idx
, new_prio
;
3424 * Test if we are atomic. Since do_exit() needs to call into
3425 * schedule() atomically, we ignore that path for now.
3426 * Otherwise, whine if we are scheduling when we should not be.
3428 if (unlikely(in_atomic() && !current
->exit_state
)) {
3429 printk(KERN_ERR
"BUG: scheduling while atomic: "
3431 current
->comm
, preempt_count(), current
->pid
);
3432 debug_show_held_locks(current
);
3433 if (irqs_disabled())
3434 print_irqtrace_events(current
);
3437 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3442 release_kernel_lock(prev
);
3443 need_resched_nonpreemptible
:
3447 * The idle thread is not allowed to schedule!
3448 * Remove this check after it has been exercised a bit.
3450 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
3451 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
3455 schedstat_inc(rq
, sched_cnt
);
3456 now
= sched_clock();
3457 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
3458 run_time
= now
- prev
->timestamp
;
3459 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
3462 run_time
= NS_MAX_SLEEP_AVG
;
3465 * Tasks charged proportionately less run_time at high sleep_avg to
3466 * delay them losing their interactive status
3468 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
3470 spin_lock_irq(&rq
->lock
);
3472 switch_count
= &prev
->nivcsw
;
3473 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3474 switch_count
= &prev
->nvcsw
;
3475 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3476 unlikely(signal_pending(prev
))))
3477 prev
->state
= TASK_RUNNING
;
3479 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
3480 rq
->nr_uninterruptible
++;
3481 deactivate_task(prev
, rq
);
3485 cpu
= smp_processor_id();
3486 if (unlikely(!rq
->nr_running
)) {
3487 idle_balance(cpu
, rq
);
3488 if (!rq
->nr_running
) {
3490 rq
->expired_timestamp
= 0;
3491 wake_sleeping_dependent(cpu
);
3497 if (unlikely(!array
->nr_active
)) {
3499 * Switch the active and expired arrays.
3501 schedstat_inc(rq
, sched_switch
);
3502 rq
->active
= rq
->expired
;
3503 rq
->expired
= array
;
3505 rq
->expired_timestamp
= 0;
3506 rq
->best_expired_prio
= MAX_PRIO
;
3509 idx
= sched_find_first_bit(array
->bitmap
);
3510 queue
= array
->queue
+ idx
;
3511 next
= list_entry(queue
->next
, struct task_struct
, run_list
);
3513 if (!rt_task(next
) && interactive_sleep(next
->sleep_type
)) {
3514 unsigned long long delta
= now
- next
->timestamp
;
3515 if (unlikely((long long)(now
- next
->timestamp
) < 0))
3518 if (next
->sleep_type
== SLEEP_INTERACTIVE
)
3519 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
3521 array
= next
->array
;
3522 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
3524 if (unlikely(next
->prio
!= new_prio
)) {
3525 dequeue_task(next
, array
);
3526 next
->prio
= new_prio
;
3527 enqueue_task(next
, array
);
3530 next
->sleep_type
= SLEEP_NORMAL
;
3531 if (dependent_sleeper(cpu
, rq
, next
))
3534 if (next
== rq
->idle
)
3535 schedstat_inc(rq
, sched_goidle
);
3537 prefetch_stack(next
);
3538 clear_tsk_need_resched(prev
);
3539 rcu_qsctr_inc(task_cpu(prev
));
3541 update_cpu_clock(prev
, rq
, now
);
3543 prev
->sleep_avg
-= run_time
;
3544 if ((long)prev
->sleep_avg
<= 0)
3545 prev
->sleep_avg
= 0;
3546 prev
->timestamp
= prev
->last_ran
= now
;
3548 sched_info_switch(prev
, next
);
3549 if (likely(prev
!= next
)) {
3550 next
->timestamp
= now
;
3555 prepare_task_switch(rq
, next
);
3556 prev
= context_switch(rq
, prev
, next
);
3559 * this_rq must be evaluated again because prev may have moved
3560 * CPUs since it called schedule(), thus the 'rq' on its stack
3561 * frame will be invalid.
3563 finish_task_switch(this_rq(), prev
);
3565 spin_unlock_irq(&rq
->lock
);
3568 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3569 goto need_resched_nonpreemptible
;
3570 preempt_enable_no_resched();
3571 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3574 EXPORT_SYMBOL(schedule
);
3576 #ifdef CONFIG_PREEMPT
3578 * this is the entry point to schedule() from in-kernel preemption
3579 * off of preempt_enable. Kernel preemptions off return from interrupt
3580 * occur there and call schedule directly.
3582 asmlinkage
void __sched
preempt_schedule(void)
3584 struct thread_info
*ti
= current_thread_info();
3585 #ifdef CONFIG_PREEMPT_BKL
3586 struct task_struct
*task
= current
;
3587 int saved_lock_depth
;
3590 * If there is a non-zero preempt_count or interrupts are disabled,
3591 * we do not want to preempt the current task. Just return..
3593 if (likely(ti
->preempt_count
|| irqs_disabled()))
3597 add_preempt_count(PREEMPT_ACTIVE
);
3599 * We keep the big kernel semaphore locked, but we
3600 * clear ->lock_depth so that schedule() doesnt
3601 * auto-release the semaphore:
3603 #ifdef CONFIG_PREEMPT_BKL
3604 saved_lock_depth
= task
->lock_depth
;
3605 task
->lock_depth
= -1;
3608 #ifdef CONFIG_PREEMPT_BKL
3609 task
->lock_depth
= saved_lock_depth
;
3611 sub_preempt_count(PREEMPT_ACTIVE
);
3613 /* we could miss a preemption opportunity between schedule and now */
3615 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3618 EXPORT_SYMBOL(preempt_schedule
);
3621 * this is the entry point to schedule() from kernel preemption
3622 * off of irq context.
3623 * Note, that this is called and return with irqs disabled. This will
3624 * protect us against recursive calling from irq.
3626 asmlinkage
void __sched
preempt_schedule_irq(void)
3628 struct thread_info
*ti
= current_thread_info();
3629 #ifdef CONFIG_PREEMPT_BKL
3630 struct task_struct
*task
= current
;
3631 int saved_lock_depth
;
3633 /* Catch callers which need to be fixed */
3634 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3637 add_preempt_count(PREEMPT_ACTIVE
);
3639 * We keep the big kernel semaphore locked, but we
3640 * clear ->lock_depth so that schedule() doesnt
3641 * auto-release the semaphore:
3643 #ifdef CONFIG_PREEMPT_BKL
3644 saved_lock_depth
= task
->lock_depth
;
3645 task
->lock_depth
= -1;
3649 local_irq_disable();
3650 #ifdef CONFIG_PREEMPT_BKL
3651 task
->lock_depth
= saved_lock_depth
;
3653 sub_preempt_count(PREEMPT_ACTIVE
);
3655 /* we could miss a preemption opportunity between schedule and now */
3657 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3661 #endif /* CONFIG_PREEMPT */
3663 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3666 return try_to_wake_up(curr
->private, mode
, sync
);
3668 EXPORT_SYMBOL(default_wake_function
);
3671 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3672 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3673 * number) then we wake all the non-exclusive tasks and one exclusive task.
3675 * There are circumstances in which we can try to wake a task which has already
3676 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3677 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3679 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3680 int nr_exclusive
, int sync
, void *key
)
3682 struct list_head
*tmp
, *next
;
3684 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3685 wait_queue_t
*curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3686 unsigned flags
= curr
->flags
;
3688 if (curr
->func(curr
, mode
, sync
, key
) &&
3689 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3695 * __wake_up - wake up threads blocked on a waitqueue.
3697 * @mode: which threads
3698 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3699 * @key: is directly passed to the wakeup function
3701 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3702 int nr_exclusive
, void *key
)
3704 unsigned long flags
;
3706 spin_lock_irqsave(&q
->lock
, flags
);
3707 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3708 spin_unlock_irqrestore(&q
->lock
, flags
);
3710 EXPORT_SYMBOL(__wake_up
);
3713 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3715 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3717 __wake_up_common(q
, mode
, 1, 0, NULL
);
3721 * __wake_up_sync - wake up threads blocked on a waitqueue.
3723 * @mode: which threads
3724 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3726 * The sync wakeup differs that the waker knows that it will schedule
3727 * away soon, so while the target thread will be woken up, it will not
3728 * be migrated to another CPU - ie. the two threads are 'synchronized'
3729 * with each other. This can prevent needless bouncing between CPUs.
3731 * On UP it can prevent extra preemption.
3734 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3736 unsigned long flags
;
3742 if (unlikely(!nr_exclusive
))
3745 spin_lock_irqsave(&q
->lock
, flags
);
3746 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3747 spin_unlock_irqrestore(&q
->lock
, flags
);
3749 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3751 void fastcall
complete(struct completion
*x
)
3753 unsigned long flags
;
3755 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3757 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3759 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3761 EXPORT_SYMBOL(complete
);
3763 void fastcall
complete_all(struct completion
*x
)
3765 unsigned long flags
;
3767 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3768 x
->done
+= UINT_MAX
/2;
3769 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3771 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3773 EXPORT_SYMBOL(complete_all
);
3775 void fastcall __sched
wait_for_completion(struct completion
*x
)
3779 spin_lock_irq(&x
->wait
.lock
);
3781 DECLARE_WAITQUEUE(wait
, current
);
3783 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3784 __add_wait_queue_tail(&x
->wait
, &wait
);
3786 __set_current_state(TASK_UNINTERRUPTIBLE
);
3787 spin_unlock_irq(&x
->wait
.lock
);
3789 spin_lock_irq(&x
->wait
.lock
);
3791 __remove_wait_queue(&x
->wait
, &wait
);
3794 spin_unlock_irq(&x
->wait
.lock
);
3796 EXPORT_SYMBOL(wait_for_completion
);
3798 unsigned long fastcall __sched
3799 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3803 spin_lock_irq(&x
->wait
.lock
);
3805 DECLARE_WAITQUEUE(wait
, current
);
3807 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3808 __add_wait_queue_tail(&x
->wait
, &wait
);
3810 __set_current_state(TASK_UNINTERRUPTIBLE
);
3811 spin_unlock_irq(&x
->wait
.lock
);
3812 timeout
= schedule_timeout(timeout
);
3813 spin_lock_irq(&x
->wait
.lock
);
3815 __remove_wait_queue(&x
->wait
, &wait
);
3819 __remove_wait_queue(&x
->wait
, &wait
);
3823 spin_unlock_irq(&x
->wait
.lock
);
3826 EXPORT_SYMBOL(wait_for_completion_timeout
);
3828 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3834 spin_lock_irq(&x
->wait
.lock
);
3836 DECLARE_WAITQUEUE(wait
, current
);
3838 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3839 __add_wait_queue_tail(&x
->wait
, &wait
);
3841 if (signal_pending(current
)) {
3843 __remove_wait_queue(&x
->wait
, &wait
);
3846 __set_current_state(TASK_INTERRUPTIBLE
);
3847 spin_unlock_irq(&x
->wait
.lock
);
3849 spin_lock_irq(&x
->wait
.lock
);
3851 __remove_wait_queue(&x
->wait
, &wait
);
3855 spin_unlock_irq(&x
->wait
.lock
);
3859 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3861 unsigned long fastcall __sched
3862 wait_for_completion_interruptible_timeout(struct completion
*x
,
3863 unsigned long timeout
)
3867 spin_lock_irq(&x
->wait
.lock
);
3869 DECLARE_WAITQUEUE(wait
, current
);
3871 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3872 __add_wait_queue_tail(&x
->wait
, &wait
);
3874 if (signal_pending(current
)) {
3875 timeout
= -ERESTARTSYS
;
3876 __remove_wait_queue(&x
->wait
, &wait
);
3879 __set_current_state(TASK_INTERRUPTIBLE
);
3880 spin_unlock_irq(&x
->wait
.lock
);
3881 timeout
= schedule_timeout(timeout
);
3882 spin_lock_irq(&x
->wait
.lock
);
3884 __remove_wait_queue(&x
->wait
, &wait
);
3888 __remove_wait_queue(&x
->wait
, &wait
);
3892 spin_unlock_irq(&x
->wait
.lock
);
3895 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3898 #define SLEEP_ON_VAR \
3899 unsigned long flags; \
3900 wait_queue_t wait; \
3901 init_waitqueue_entry(&wait, current);
3903 #define SLEEP_ON_HEAD \
3904 spin_lock_irqsave(&q->lock,flags); \
3905 __add_wait_queue(q, &wait); \
3906 spin_unlock(&q->lock);
3908 #define SLEEP_ON_TAIL \
3909 spin_lock_irq(&q->lock); \
3910 __remove_wait_queue(q, &wait); \
3911 spin_unlock_irqrestore(&q->lock, flags);
3913 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3917 current
->state
= TASK_INTERRUPTIBLE
;
3923 EXPORT_SYMBOL(interruptible_sleep_on
);
3925 long fastcall __sched
3926 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3930 current
->state
= TASK_INTERRUPTIBLE
;
3933 timeout
= schedule_timeout(timeout
);
3938 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3940 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3944 current
->state
= TASK_UNINTERRUPTIBLE
;
3950 EXPORT_SYMBOL(sleep_on
);
3952 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3956 current
->state
= TASK_UNINTERRUPTIBLE
;
3959 timeout
= schedule_timeout(timeout
);
3965 EXPORT_SYMBOL(sleep_on_timeout
);
3967 #ifdef CONFIG_RT_MUTEXES
3970 * rt_mutex_setprio - set the current priority of a task
3972 * @prio: prio value (kernel-internal form)
3974 * This function changes the 'effective' priority of a task. It does
3975 * not touch ->normal_prio like __setscheduler().
3977 * Used by the rt_mutex code to implement priority inheritance logic.
3979 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
3981 struct prio_array
*array
;
3982 unsigned long flags
;
3986 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
3988 rq
= task_rq_lock(p
, &flags
);
3993 dequeue_task(p
, array
);
3998 * If changing to an RT priority then queue it
3999 * in the active array!
4003 enqueue_task(p
, array
);
4005 * Reschedule if we are currently running on this runqueue and
4006 * our priority decreased, or if we are not currently running on
4007 * this runqueue and our priority is higher than the current's
4009 if (task_running(rq
, p
)) {
4010 if (p
->prio
> oldprio
)
4011 resched_task(rq
->curr
);
4012 } else if (TASK_PREEMPTS_CURR(p
, rq
))
4013 resched_task(rq
->curr
);
4015 task_rq_unlock(rq
, &flags
);
4020 void set_user_nice(struct task_struct
*p
, long nice
)
4022 struct prio_array
*array
;
4023 int old_prio
, delta
;
4024 unsigned long flags
;
4027 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4030 * We have to be careful, if called from sys_setpriority(),
4031 * the task might be in the middle of scheduling on another CPU.
4033 rq
= task_rq_lock(p
, &flags
);
4035 * The RT priorities are set via sched_setscheduler(), but we still
4036 * allow the 'normal' nice value to be set - but as expected
4037 * it wont have any effect on scheduling until the task is
4038 * not SCHED_NORMAL/SCHED_BATCH:
4040 if (has_rt_policy(p
)) {
4041 p
->static_prio
= NICE_TO_PRIO(nice
);
4046 dequeue_task(p
, array
);
4047 dec_raw_weighted_load(rq
, p
);
4050 p
->static_prio
= NICE_TO_PRIO(nice
);
4053 p
->prio
= effective_prio(p
);
4054 delta
= p
->prio
- old_prio
;
4057 enqueue_task(p
, array
);
4058 inc_raw_weighted_load(rq
, p
);
4060 * If the task increased its priority or is running and
4061 * lowered its priority, then reschedule its CPU:
4063 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4064 resched_task(rq
->curr
);
4067 task_rq_unlock(rq
, &flags
);
4069 EXPORT_SYMBOL(set_user_nice
);
4072 * can_nice - check if a task can reduce its nice value
4076 int can_nice(const struct task_struct
*p
, const int nice
)
4078 /* convert nice value [19,-20] to rlimit style value [1,40] */
4079 int nice_rlim
= 20 - nice
;
4081 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4082 capable(CAP_SYS_NICE
));
4085 #ifdef __ARCH_WANT_SYS_NICE
4088 * sys_nice - change the priority of the current process.
4089 * @increment: priority increment
4091 * sys_setpriority is a more generic, but much slower function that
4092 * does similar things.
4094 asmlinkage
long sys_nice(int increment
)
4099 * Setpriority might change our priority at the same moment.
4100 * We don't have to worry. Conceptually one call occurs first
4101 * and we have a single winner.
4103 if (increment
< -40)
4108 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4114 if (increment
< 0 && !can_nice(current
, nice
))
4117 retval
= security_task_setnice(current
, nice
);
4121 set_user_nice(current
, nice
);
4128 * task_prio - return the priority value of a given task.
4129 * @p: the task in question.
4131 * This is the priority value as seen by users in /proc.
4132 * RT tasks are offset by -200. Normal tasks are centered
4133 * around 0, value goes from -16 to +15.
4135 int task_prio(const struct task_struct
*p
)
4137 return p
->prio
- MAX_RT_PRIO
;
4141 * task_nice - return the nice value of a given task.
4142 * @p: the task in question.
4144 int task_nice(const struct task_struct
*p
)
4146 return TASK_NICE(p
);
4148 EXPORT_SYMBOL_GPL(task_nice
);
4151 * idle_cpu - is a given cpu idle currently?
4152 * @cpu: the processor in question.
4154 int idle_cpu(int cpu
)
4156 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4160 * idle_task - return the idle task for a given cpu.
4161 * @cpu: the processor in question.
4163 struct task_struct
*idle_task(int cpu
)
4165 return cpu_rq(cpu
)->idle
;
4169 * find_process_by_pid - find a process with a matching PID value.
4170 * @pid: the pid in question.
4172 static inline struct task_struct
*find_process_by_pid(pid_t pid
)
4174 return pid
? find_task_by_pid(pid
) : current
;
4177 /* Actually do priority change: must hold rq lock. */
4178 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
4183 p
->rt_priority
= prio
;
4184 p
->normal_prio
= normal_prio(p
);
4185 /* we are holding p->pi_lock already */
4186 p
->prio
= rt_mutex_getprio(p
);
4188 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
4190 if (policy
== SCHED_BATCH
)
4196 * sched_setscheduler - change the scheduling policy and/or RT priority of
4198 * @p: the task in question.
4199 * @policy: new policy.
4200 * @param: structure containing the new RT priority.
4202 * NOTE: the task may be already dead
4204 int sched_setscheduler(struct task_struct
*p
, int policy
,
4205 struct sched_param
*param
)
4207 int retval
, oldprio
, oldpolicy
= -1;
4208 struct prio_array
*array
;
4209 unsigned long flags
;
4212 /* may grab non-irq protected spin_locks */
4213 BUG_ON(in_interrupt());
4215 /* double check policy once rq lock held */
4217 policy
= oldpolicy
= p
->policy
;
4218 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4219 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
)
4222 * Valid priorities for SCHED_FIFO and SCHED_RR are
4223 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
4226 if (param
->sched_priority
< 0 ||
4227 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4228 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4230 if (is_rt_policy(policy
) != (param
->sched_priority
!= 0))
4234 * Allow unprivileged RT tasks to decrease priority:
4236 if (!capable(CAP_SYS_NICE
)) {
4237 if (is_rt_policy(policy
)) {
4238 unsigned long rlim_rtprio
;
4239 unsigned long flags
;
4241 if (!lock_task_sighand(p
, &flags
))
4243 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4244 unlock_task_sighand(p
, &flags
);
4246 /* can't set/change the rt policy */
4247 if (policy
!= p
->policy
&& !rlim_rtprio
)
4250 /* can't increase priority */
4251 if (param
->sched_priority
> p
->rt_priority
&&
4252 param
->sched_priority
> rlim_rtprio
)
4256 /* can't change other user's priorities */
4257 if ((current
->euid
!= p
->euid
) &&
4258 (current
->euid
!= p
->uid
))
4262 retval
= security_task_setscheduler(p
, policy
, param
);
4266 * make sure no PI-waiters arrive (or leave) while we are
4267 * changing the priority of the task:
4269 spin_lock_irqsave(&p
->pi_lock
, flags
);
4271 * To be able to change p->policy safely, the apropriate
4272 * runqueue lock must be held.
4274 rq
= __task_rq_lock(p
);
4275 /* recheck policy now with rq lock held */
4276 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4277 policy
= oldpolicy
= -1;
4278 __task_rq_unlock(rq
);
4279 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4284 deactivate_task(p
, rq
);
4286 __setscheduler(p
, policy
, param
->sched_priority
);
4288 __activate_task(p
, rq
);
4290 * Reschedule if we are currently running on this runqueue and
4291 * our priority decreased, or if we are not currently running on
4292 * this runqueue and our priority is higher than the current's
4294 if (task_running(rq
, p
)) {
4295 if (p
->prio
> oldprio
)
4296 resched_task(rq
->curr
);
4297 } else if (TASK_PREEMPTS_CURR(p
, rq
))
4298 resched_task(rq
->curr
);
4300 __task_rq_unlock(rq
);
4301 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4303 rt_mutex_adjust_pi(p
);
4307 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4310 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4312 struct sched_param lparam
;
4313 struct task_struct
*p
;
4316 if (!param
|| pid
< 0)
4318 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4323 p
= find_process_by_pid(pid
);
4325 retval
= sched_setscheduler(p
, policy
, &lparam
);
4332 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4333 * @pid: the pid in question.
4334 * @policy: new policy.
4335 * @param: structure containing the new RT priority.
4337 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
4338 struct sched_param __user
*param
)
4340 /* negative values for policy are not valid */
4344 return do_sched_setscheduler(pid
, policy
, param
);
4348 * sys_sched_setparam - set/change the RT priority of a thread
4349 * @pid: the pid in question.
4350 * @param: structure containing the new RT priority.
4352 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4354 return do_sched_setscheduler(pid
, -1, param
);
4358 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4359 * @pid: the pid in question.
4361 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4363 struct task_struct
*p
;
4364 int retval
= -EINVAL
;
4370 read_lock(&tasklist_lock
);
4371 p
= find_process_by_pid(pid
);
4373 retval
= security_task_getscheduler(p
);
4377 read_unlock(&tasklist_lock
);
4384 * sys_sched_getscheduler - get the RT priority of a thread
4385 * @pid: the pid in question.
4386 * @param: structure containing the RT priority.
4388 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4390 struct sched_param lp
;
4391 struct task_struct
*p
;
4392 int retval
= -EINVAL
;
4394 if (!param
|| pid
< 0)
4397 read_lock(&tasklist_lock
);
4398 p
= find_process_by_pid(pid
);
4403 retval
= security_task_getscheduler(p
);
4407 lp
.sched_priority
= p
->rt_priority
;
4408 read_unlock(&tasklist_lock
);
4411 * This one might sleep, we cannot do it with a spinlock held ...
4413 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4419 read_unlock(&tasklist_lock
);
4423 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4425 cpumask_t cpus_allowed
;
4426 struct task_struct
*p
;
4430 read_lock(&tasklist_lock
);
4432 p
= find_process_by_pid(pid
);
4434 read_unlock(&tasklist_lock
);
4435 unlock_cpu_hotplug();
4440 * It is not safe to call set_cpus_allowed with the
4441 * tasklist_lock held. We will bump the task_struct's
4442 * usage count and then drop tasklist_lock.
4445 read_unlock(&tasklist_lock
);
4448 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4449 !capable(CAP_SYS_NICE
))
4452 retval
= security_task_setscheduler(p
, 0, NULL
);
4456 cpus_allowed
= cpuset_cpus_allowed(p
);
4457 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4458 retval
= set_cpus_allowed(p
, new_mask
);
4462 unlock_cpu_hotplug();
4466 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4467 cpumask_t
*new_mask
)
4469 if (len
< sizeof(cpumask_t
)) {
4470 memset(new_mask
, 0, sizeof(cpumask_t
));
4471 } else if (len
> sizeof(cpumask_t
)) {
4472 len
= sizeof(cpumask_t
);
4474 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4478 * sys_sched_setaffinity - set the cpu affinity of a process
4479 * @pid: pid of the process
4480 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4481 * @user_mask_ptr: user-space pointer to the new cpu mask
4483 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4484 unsigned long __user
*user_mask_ptr
)
4489 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4493 return sched_setaffinity(pid
, new_mask
);
4497 * Represents all cpu's present in the system
4498 * In systems capable of hotplug, this map could dynamically grow
4499 * as new cpu's are detected in the system via any platform specific
4500 * method, such as ACPI for e.g.
4503 cpumask_t cpu_present_map __read_mostly
;
4504 EXPORT_SYMBOL(cpu_present_map
);
4507 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4508 EXPORT_SYMBOL(cpu_online_map
);
4510 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4511 EXPORT_SYMBOL(cpu_possible_map
);
4514 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4516 struct task_struct
*p
;
4520 read_lock(&tasklist_lock
);
4523 p
= find_process_by_pid(pid
);
4527 retval
= security_task_getscheduler(p
);
4531 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4534 read_unlock(&tasklist_lock
);
4535 unlock_cpu_hotplug();
4543 * sys_sched_getaffinity - get the cpu affinity of a process
4544 * @pid: pid of the process
4545 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4546 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4548 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4549 unsigned long __user
*user_mask_ptr
)
4554 if (len
< sizeof(cpumask_t
))
4557 ret
= sched_getaffinity(pid
, &mask
);
4561 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4564 return sizeof(cpumask_t
);
4568 * sys_sched_yield - yield the current processor to other threads.
4570 * this function yields the current CPU by moving the calling thread
4571 * to the expired array. If there are no other threads running on this
4572 * CPU then this function will return.
4574 asmlinkage
long sys_sched_yield(void)
4576 struct rq
*rq
= this_rq_lock();
4577 struct prio_array
*array
= current
->array
, *target
= rq
->expired
;
4579 schedstat_inc(rq
, yld_cnt
);
4581 * We implement yielding by moving the task into the expired
4584 * (special rule: RT tasks will just roundrobin in the active
4587 if (rt_task(current
))
4588 target
= rq
->active
;
4590 if (array
->nr_active
== 1) {
4591 schedstat_inc(rq
, yld_act_empty
);
4592 if (!rq
->expired
->nr_active
)
4593 schedstat_inc(rq
, yld_both_empty
);
4594 } else if (!rq
->expired
->nr_active
)
4595 schedstat_inc(rq
, yld_exp_empty
);
4597 if (array
!= target
) {
4598 dequeue_task(current
, array
);
4599 enqueue_task(current
, target
);
4602 * requeue_task is cheaper so perform that if possible.
4604 requeue_task(current
, array
);
4607 * Since we are going to call schedule() anyway, there's
4608 * no need to preempt or enable interrupts:
4610 __release(rq
->lock
);
4611 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4612 _raw_spin_unlock(&rq
->lock
);
4613 preempt_enable_no_resched();
4620 static void __cond_resched(void)
4622 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4623 __might_sleep(__FILE__
, __LINE__
);
4626 * The BKS might be reacquired before we have dropped
4627 * PREEMPT_ACTIVE, which could trigger a second
4628 * cond_resched() call.
4631 add_preempt_count(PREEMPT_ACTIVE
);
4633 sub_preempt_count(PREEMPT_ACTIVE
);
4634 } while (need_resched());
4637 int __sched
cond_resched(void)
4639 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4640 system_state
== SYSTEM_RUNNING
) {
4646 EXPORT_SYMBOL(cond_resched
);
4649 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4650 * call schedule, and on return reacquire the lock.
4652 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4653 * operations here to prevent schedule() from being called twice (once via
4654 * spin_unlock(), once by hand).
4656 int cond_resched_lock(spinlock_t
*lock
)
4660 if (need_lockbreak(lock
)) {
4666 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4667 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4668 _raw_spin_unlock(lock
);
4669 preempt_enable_no_resched();
4676 EXPORT_SYMBOL(cond_resched_lock
);
4678 int __sched
cond_resched_softirq(void)
4680 BUG_ON(!in_softirq());
4682 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4683 raw_local_irq_disable();
4685 raw_local_irq_enable();
4692 EXPORT_SYMBOL(cond_resched_softirq
);
4695 * yield - yield the current processor to other threads.
4697 * this is a shortcut for kernel-space yielding - it marks the
4698 * thread runnable and calls sys_sched_yield().
4700 void __sched
yield(void)
4702 set_current_state(TASK_RUNNING
);
4705 EXPORT_SYMBOL(yield
);
4708 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4709 * that process accounting knows that this is a task in IO wait state.
4711 * But don't do that if it is a deliberate, throttling IO wait (this task
4712 * has set its backing_dev_info: the queue against which it should throttle)
4714 void __sched
io_schedule(void)
4716 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4718 delayacct_blkio_start();
4719 atomic_inc(&rq
->nr_iowait
);
4721 atomic_dec(&rq
->nr_iowait
);
4722 delayacct_blkio_end();
4724 EXPORT_SYMBOL(io_schedule
);
4726 long __sched
io_schedule_timeout(long timeout
)
4728 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4731 delayacct_blkio_start();
4732 atomic_inc(&rq
->nr_iowait
);
4733 ret
= schedule_timeout(timeout
);
4734 atomic_dec(&rq
->nr_iowait
);
4735 delayacct_blkio_end();
4740 * sys_sched_get_priority_max - return maximum RT priority.
4741 * @policy: scheduling class.
4743 * this syscall returns the maximum rt_priority that can be used
4744 * by a given scheduling class.
4746 asmlinkage
long sys_sched_get_priority_max(int policy
)
4753 ret
= MAX_USER_RT_PRIO
-1;
4764 * sys_sched_get_priority_min - return minimum RT priority.
4765 * @policy: scheduling class.
4767 * this syscall returns the minimum rt_priority that can be used
4768 * by a given scheduling class.
4770 asmlinkage
long sys_sched_get_priority_min(int policy
)
4787 * sys_sched_rr_get_interval - return the default timeslice of a process.
4788 * @pid: pid of the process.
4789 * @interval: userspace pointer to the timeslice value.
4791 * this syscall writes the default timeslice value of a given process
4792 * into the user-space timespec buffer. A value of '0' means infinity.
4795 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4797 struct task_struct
*p
;
4798 int retval
= -EINVAL
;
4805 read_lock(&tasklist_lock
);
4806 p
= find_process_by_pid(pid
);
4810 retval
= security_task_getscheduler(p
);
4814 jiffies_to_timespec(p
->policy
== SCHED_FIFO
?
4815 0 : task_timeslice(p
), &t
);
4816 read_unlock(&tasklist_lock
);
4817 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4821 read_unlock(&tasklist_lock
);
4825 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4827 if (list_empty(&p
->children
))
4829 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4832 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4834 if (p
->sibling
.prev
==&p
->parent
->children
)
4836 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4839 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4841 if (p
->sibling
.next
==&p
->parent
->children
)
4843 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4846 static const char stat_nam
[] = "RSDTtZX";
4848 static void show_task(struct task_struct
*p
)
4850 struct task_struct
*relative
;
4851 unsigned long free
= 0;
4854 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4855 printk("%-13.13s %c", p
->comm
,
4856 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4857 #if (BITS_PER_LONG == 32)
4858 if (state
== TASK_RUNNING
)
4859 printk(" running ");
4861 printk(" %08lX ", thread_saved_pc(p
));
4863 if (state
== TASK_RUNNING
)
4864 printk(" running task ");
4866 printk(" %016lx ", thread_saved_pc(p
));
4868 #ifdef CONFIG_DEBUG_STACK_USAGE
4870 unsigned long *n
= end_of_stack(p
);
4873 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4876 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4877 if ((relative
= eldest_child(p
)))
4878 printk("%5d ", relative
->pid
);
4881 if ((relative
= younger_sibling(p
)))
4882 printk("%7d", relative
->pid
);
4885 if ((relative
= older_sibling(p
)))
4886 printk(" %5d", relative
->pid
);
4890 printk(" (L-TLB)\n");
4892 printk(" (NOTLB)\n");
4894 if (state
!= TASK_RUNNING
)
4895 show_stack(p
, NULL
);
4898 void show_state_filter(unsigned long state_filter
)
4900 struct task_struct
*g
, *p
;
4902 #if (BITS_PER_LONG == 32)
4905 printk(" task PC stack pid father child younger older\n");
4909 printk(" task PC stack pid father child younger older\n");
4911 read_lock(&tasklist_lock
);
4912 do_each_thread(g
, p
) {
4914 * reset the NMI-timeout, listing all files on a slow
4915 * console might take alot of time:
4917 touch_nmi_watchdog();
4918 if (p
->state
& state_filter
)
4920 } while_each_thread(g
, p
);
4922 read_unlock(&tasklist_lock
);
4924 * Only show locks if all tasks are dumped:
4926 if (state_filter
== -1)
4927 debug_show_all_locks();
4931 * init_idle - set up an idle thread for a given CPU
4932 * @idle: task in question
4933 * @cpu: cpu the idle task belongs to
4935 * NOTE: this function does not set the idle thread's NEED_RESCHED
4936 * flag, to make booting more robust.
4938 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4940 struct rq
*rq
= cpu_rq(cpu
);
4941 unsigned long flags
;
4943 idle
->timestamp
= sched_clock();
4944 idle
->sleep_avg
= 0;
4946 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4947 idle
->state
= TASK_RUNNING
;
4948 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4949 set_task_cpu(idle
, cpu
);
4951 spin_lock_irqsave(&rq
->lock
, flags
);
4952 rq
->curr
= rq
->idle
= idle
;
4953 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4956 spin_unlock_irqrestore(&rq
->lock
, flags
);
4958 /* Set the preempt count _outside_ the spinlocks! */
4959 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4960 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4962 task_thread_info(idle
)->preempt_count
= 0;
4967 * In a system that switches off the HZ timer nohz_cpu_mask
4968 * indicates which cpus entered this state. This is used
4969 * in the rcu update to wait only for active cpus. For system
4970 * which do not switch off the HZ timer nohz_cpu_mask should
4971 * always be CPU_MASK_NONE.
4973 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4977 * This is how migration works:
4979 * 1) we queue a struct migration_req structure in the source CPU's
4980 * runqueue and wake up that CPU's migration thread.
4981 * 2) we down() the locked semaphore => thread blocks.
4982 * 3) migration thread wakes up (implicitly it forces the migrated
4983 * thread off the CPU)
4984 * 4) it gets the migration request and checks whether the migrated
4985 * task is still in the wrong runqueue.
4986 * 5) if it's in the wrong runqueue then the migration thread removes
4987 * it and puts it into the right queue.
4988 * 6) migration thread up()s the semaphore.
4989 * 7) we wake up and the migration is done.
4993 * Change a given task's CPU affinity. Migrate the thread to a
4994 * proper CPU and schedule it away if the CPU it's executing on
4995 * is removed from the allowed bitmask.
4997 * NOTE: the caller must have a valid reference to the task, the
4998 * task must not exit() & deallocate itself prematurely. The
4999 * call is not atomic; no spinlocks may be held.
5001 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5003 struct migration_req req
;
5004 unsigned long flags
;
5008 rq
= task_rq_lock(p
, &flags
);
5009 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5014 p
->cpus_allowed
= new_mask
;
5015 /* Can the task run on the task's current CPU? If so, we're done */
5016 if (cpu_isset(task_cpu(p
), new_mask
))
5019 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5020 /* Need help from migration thread: drop lock and wait. */
5021 task_rq_unlock(rq
, &flags
);
5022 wake_up_process(rq
->migration_thread
);
5023 wait_for_completion(&req
.done
);
5024 tlb_migrate_finish(p
->mm
);
5028 task_rq_unlock(rq
, &flags
);
5032 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5035 * Move (not current) task off this cpu, onto dest cpu. We're doing
5036 * this because either it can't run here any more (set_cpus_allowed()
5037 * away from this CPU, or CPU going down), or because we're
5038 * attempting to rebalance this task on exec (sched_exec).
5040 * So we race with normal scheduler movements, but that's OK, as long
5041 * as the task is no longer on this CPU.
5043 * Returns non-zero if task was successfully migrated.
5045 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5047 struct rq
*rq_dest
, *rq_src
;
5050 if (unlikely(cpu_is_offline(dest_cpu
)))
5053 rq_src
= cpu_rq(src_cpu
);
5054 rq_dest
= cpu_rq(dest_cpu
);
5056 double_rq_lock(rq_src
, rq_dest
);
5057 /* Already moved. */
5058 if (task_cpu(p
) != src_cpu
)
5060 /* Affinity changed (again). */
5061 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5064 set_task_cpu(p
, dest_cpu
);
5067 * Sync timestamp with rq_dest's before activating.
5068 * The same thing could be achieved by doing this step
5069 * afterwards, and pretending it was a local activate.
5070 * This way is cleaner and logically correct.
5072 p
->timestamp
= p
->timestamp
- rq_src
->most_recent_timestamp
5073 + rq_dest
->most_recent_timestamp
;
5074 deactivate_task(p
, rq_src
);
5075 __activate_task(p
, rq_dest
);
5076 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
5077 resched_task(rq_dest
->curr
);
5081 double_rq_unlock(rq_src
, rq_dest
);
5086 * migration_thread - this is a highprio system thread that performs
5087 * thread migration by bumping thread off CPU then 'pushing' onto
5090 static int migration_thread(void *data
)
5092 int cpu
= (long)data
;
5096 BUG_ON(rq
->migration_thread
!= current
);
5098 set_current_state(TASK_INTERRUPTIBLE
);
5099 while (!kthread_should_stop()) {
5100 struct migration_req
*req
;
5101 struct list_head
*head
;
5105 spin_lock_irq(&rq
->lock
);
5107 if (cpu_is_offline(cpu
)) {
5108 spin_unlock_irq(&rq
->lock
);
5112 if (rq
->active_balance
) {
5113 active_load_balance(rq
, cpu
);
5114 rq
->active_balance
= 0;
5117 head
= &rq
->migration_queue
;
5119 if (list_empty(head
)) {
5120 spin_unlock_irq(&rq
->lock
);
5122 set_current_state(TASK_INTERRUPTIBLE
);
5125 req
= list_entry(head
->next
, struct migration_req
, list
);
5126 list_del_init(head
->next
);
5128 spin_unlock(&rq
->lock
);
5129 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5132 complete(&req
->done
);
5134 __set_current_state(TASK_RUNNING
);
5138 /* Wait for kthread_stop */
5139 set_current_state(TASK_INTERRUPTIBLE
);
5140 while (!kthread_should_stop()) {
5142 set_current_state(TASK_INTERRUPTIBLE
);
5144 __set_current_state(TASK_RUNNING
);
5148 #ifdef CONFIG_HOTPLUG_CPU
5150 * Figure out where task on dead CPU should go, use force if neccessary.
5151 * NOTE: interrupts should be disabled by the caller
5153 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5155 unsigned long flags
;
5162 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5163 cpus_and(mask
, mask
, p
->cpus_allowed
);
5164 dest_cpu
= any_online_cpu(mask
);
5166 /* On any allowed CPU? */
5167 if (dest_cpu
== NR_CPUS
)
5168 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5170 /* No more Mr. Nice Guy. */
5171 if (dest_cpu
== NR_CPUS
) {
5172 rq
= task_rq_lock(p
, &flags
);
5173 cpus_setall(p
->cpus_allowed
);
5174 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5175 task_rq_unlock(rq
, &flags
);
5178 * Don't tell them about moving exiting tasks or
5179 * kernel threads (both mm NULL), since they never
5182 if (p
->mm
&& printk_ratelimit())
5183 printk(KERN_INFO
"process %d (%s) no "
5184 "longer affine to cpu%d\n",
5185 p
->pid
, p
->comm
, dead_cpu
);
5187 if (!__migrate_task(p
, dead_cpu
, dest_cpu
))
5192 * While a dead CPU has no uninterruptible tasks queued at this point,
5193 * it might still have a nonzero ->nr_uninterruptible counter, because
5194 * for performance reasons the counter is not stricly tracking tasks to
5195 * their home CPUs. So we just add the counter to another CPU's counter,
5196 * to keep the global sum constant after CPU-down:
5198 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5200 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5201 unsigned long flags
;
5203 local_irq_save(flags
);
5204 double_rq_lock(rq_src
, rq_dest
);
5205 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5206 rq_src
->nr_uninterruptible
= 0;
5207 double_rq_unlock(rq_src
, rq_dest
);
5208 local_irq_restore(flags
);
5211 /* Run through task list and migrate tasks from the dead cpu. */
5212 static void migrate_live_tasks(int src_cpu
)
5214 struct task_struct
*p
, *t
;
5216 write_lock_irq(&tasklist_lock
);
5218 do_each_thread(t
, p
) {
5222 if (task_cpu(p
) == src_cpu
)
5223 move_task_off_dead_cpu(src_cpu
, p
);
5224 } while_each_thread(t
, p
);
5226 write_unlock_irq(&tasklist_lock
);
5229 /* Schedules idle task to be the next runnable task on current CPU.
5230 * It does so by boosting its priority to highest possible and adding it to
5231 * the _front_ of the runqueue. Used by CPU offline code.
5233 void sched_idle_next(void)
5235 int this_cpu
= smp_processor_id();
5236 struct rq
*rq
= cpu_rq(this_cpu
);
5237 struct task_struct
*p
= rq
->idle
;
5238 unsigned long flags
;
5240 /* cpu has to be offline */
5241 BUG_ON(cpu_online(this_cpu
));
5244 * Strictly not necessary since rest of the CPUs are stopped by now
5245 * and interrupts disabled on the current cpu.
5247 spin_lock_irqsave(&rq
->lock
, flags
);
5249 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5251 /* Add idle task to the _front_ of its priority queue: */
5252 __activate_idle_task(p
, rq
);
5254 spin_unlock_irqrestore(&rq
->lock
, flags
);
5258 * Ensures that the idle task is using init_mm right before its cpu goes
5261 void idle_task_exit(void)
5263 struct mm_struct
*mm
= current
->active_mm
;
5265 BUG_ON(cpu_online(smp_processor_id()));
5268 switch_mm(mm
, &init_mm
, current
);
5272 /* called under rq->lock with disabled interrupts */
5273 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5275 struct rq
*rq
= cpu_rq(dead_cpu
);
5277 /* Must be exiting, otherwise would be on tasklist. */
5278 BUG_ON(p
->exit_state
!= EXIT_ZOMBIE
&& p
->exit_state
!= EXIT_DEAD
);
5280 /* Cannot have done final schedule yet: would have vanished. */
5281 BUG_ON(p
->state
== TASK_DEAD
);
5286 * Drop lock around migration; if someone else moves it,
5287 * that's OK. No task can be added to this CPU, so iteration is
5289 * NOTE: interrupts should be left disabled --dev@
5291 spin_unlock(&rq
->lock
);
5292 move_task_off_dead_cpu(dead_cpu
, p
);
5293 spin_lock(&rq
->lock
);
5298 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5299 static void migrate_dead_tasks(unsigned int dead_cpu
)
5301 struct rq
*rq
= cpu_rq(dead_cpu
);
5302 unsigned int arr
, i
;
5304 for (arr
= 0; arr
< 2; arr
++) {
5305 for (i
= 0; i
< MAX_PRIO
; i
++) {
5306 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
5308 while (!list_empty(list
))
5309 migrate_dead(dead_cpu
, list_entry(list
->next
,
5310 struct task_struct
, run_list
));
5314 #endif /* CONFIG_HOTPLUG_CPU */
5317 * migration_call - callback that gets triggered when a CPU is added.
5318 * Here we can start up the necessary migration thread for the new CPU.
5320 static int __cpuinit
5321 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5323 struct task_struct
*p
;
5324 int cpu
= (long)hcpu
;
5325 unsigned long flags
;
5329 case CPU_UP_PREPARE
:
5330 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
5333 p
->flags
|= PF_NOFREEZE
;
5334 kthread_bind(p
, cpu
);
5335 /* Must be high prio: stop_machine expects to yield to it. */
5336 rq
= task_rq_lock(p
, &flags
);
5337 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5338 task_rq_unlock(rq
, &flags
);
5339 cpu_rq(cpu
)->migration_thread
= p
;
5343 /* Strictly unneccessary, as first user will wake it. */
5344 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5347 #ifdef CONFIG_HOTPLUG_CPU
5348 case CPU_UP_CANCELED
:
5349 if (!cpu_rq(cpu
)->migration_thread
)
5351 /* Unbind it from offline cpu so it can run. Fall thru. */
5352 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5353 any_online_cpu(cpu_online_map
));
5354 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5355 cpu_rq(cpu
)->migration_thread
= NULL
;
5359 migrate_live_tasks(cpu
);
5361 kthread_stop(rq
->migration_thread
);
5362 rq
->migration_thread
= NULL
;
5363 /* Idle task back to normal (off runqueue, low prio) */
5364 rq
= task_rq_lock(rq
->idle
, &flags
);
5365 deactivate_task(rq
->idle
, rq
);
5366 rq
->idle
->static_prio
= MAX_PRIO
;
5367 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
5368 migrate_dead_tasks(cpu
);
5369 task_rq_unlock(rq
, &flags
);
5370 migrate_nr_uninterruptible(rq
);
5371 BUG_ON(rq
->nr_running
!= 0);
5373 /* No need to migrate the tasks: it was best-effort if
5374 * they didn't do lock_cpu_hotplug(). Just wake up
5375 * the requestors. */
5376 spin_lock_irq(&rq
->lock
);
5377 while (!list_empty(&rq
->migration_queue
)) {
5378 struct migration_req
*req
;
5380 req
= list_entry(rq
->migration_queue
.next
,
5381 struct migration_req
, list
);
5382 list_del_init(&req
->list
);
5383 complete(&req
->done
);
5385 spin_unlock_irq(&rq
->lock
);
5392 /* Register at highest priority so that task migration (migrate_all_tasks)
5393 * happens before everything else.
5395 static struct notifier_block __cpuinitdata migration_notifier
= {
5396 .notifier_call
= migration_call
,
5400 int __init
migration_init(void)
5402 void *cpu
= (void *)(long)smp_processor_id();
5405 /* Start one for the boot CPU: */
5406 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5407 BUG_ON(err
== NOTIFY_BAD
);
5408 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5409 register_cpu_notifier(&migration_notifier
);
5416 #undef SCHED_DOMAIN_DEBUG
5417 #ifdef SCHED_DOMAIN_DEBUG
5418 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5423 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5427 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5432 struct sched_group
*group
= sd
->groups
;
5433 cpumask_t groupmask
;
5435 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5436 cpus_clear(groupmask
);
5439 for (i
= 0; i
< level
+ 1; i
++)
5441 printk("domain %d: ", level
);
5443 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5444 printk("does not load-balance\n");
5446 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5451 printk("span %s\n", str
);
5453 if (!cpu_isset(cpu
, sd
->span
))
5454 printk(KERN_ERR
"ERROR: domain->span does not contain "
5456 if (!cpu_isset(cpu
, group
->cpumask
))
5457 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5461 for (i
= 0; i
< level
+ 2; i
++)
5467 printk(KERN_ERR
"ERROR: group is NULL\n");
5471 if (!group
->cpu_power
) {
5473 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5477 if (!cpus_weight(group
->cpumask
)) {
5479 printk(KERN_ERR
"ERROR: empty group\n");
5482 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5484 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5487 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5489 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5492 group
= group
->next
;
5493 } while (group
!= sd
->groups
);
5496 if (!cpus_equal(sd
->span
, groupmask
))
5497 printk(KERN_ERR
"ERROR: groups don't span "
5505 if (!cpus_subset(groupmask
, sd
->span
))
5506 printk(KERN_ERR
"ERROR: parent span is not a superset "
5507 "of domain->span\n");
5512 # define sched_domain_debug(sd, cpu) do { } while (0)
5515 static int sd_degenerate(struct sched_domain
*sd
)
5517 if (cpus_weight(sd
->span
) == 1)
5520 /* Following flags need at least 2 groups */
5521 if (sd
->flags
& (SD_LOAD_BALANCE
|
5522 SD_BALANCE_NEWIDLE
|
5526 SD_SHARE_PKG_RESOURCES
)) {
5527 if (sd
->groups
!= sd
->groups
->next
)
5531 /* Following flags don't use groups */
5532 if (sd
->flags
& (SD_WAKE_IDLE
|
5541 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5543 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5545 if (sd_degenerate(parent
))
5548 if (!cpus_equal(sd
->span
, parent
->span
))
5551 /* Does parent contain flags not in child? */
5552 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5553 if (cflags
& SD_WAKE_AFFINE
)
5554 pflags
&= ~SD_WAKE_BALANCE
;
5555 /* Flags needing groups don't count if only 1 group in parent */
5556 if (parent
->groups
== parent
->groups
->next
) {
5557 pflags
&= ~(SD_LOAD_BALANCE
|
5558 SD_BALANCE_NEWIDLE
|
5562 SD_SHARE_PKG_RESOURCES
);
5564 if (~cflags
& pflags
)
5571 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5572 * hold the hotplug lock.
5574 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5576 struct rq
*rq
= cpu_rq(cpu
);
5577 struct sched_domain
*tmp
;
5579 /* Remove the sched domains which do not contribute to scheduling. */
5580 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5581 struct sched_domain
*parent
= tmp
->parent
;
5584 if (sd_parent_degenerate(tmp
, parent
)) {
5585 tmp
->parent
= parent
->parent
;
5587 parent
->parent
->child
= tmp
;
5591 if (sd
&& sd_degenerate(sd
)) {
5597 sched_domain_debug(sd
, cpu
);
5599 rcu_assign_pointer(rq
->sd
, sd
);
5602 /* cpus with isolated domains */
5603 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5605 /* Setup the mask of cpus configured for isolated domains */
5606 static int __init
isolated_cpu_setup(char *str
)
5608 int ints
[NR_CPUS
], i
;
5610 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5611 cpus_clear(cpu_isolated_map
);
5612 for (i
= 1; i
<= ints
[0]; i
++)
5613 if (ints
[i
] < NR_CPUS
)
5614 cpu_set(ints
[i
], cpu_isolated_map
);
5618 __setup ("isolcpus=", isolated_cpu_setup
);
5621 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5622 * to a function which identifies what group(along with sched group) a CPU
5623 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5624 * (due to the fact that we keep track of groups covered with a cpumask_t).
5626 * init_sched_build_groups will build a circular linked list of the groups
5627 * covered by the given span, and will set each group's ->cpumask correctly,
5628 * and ->cpu_power to 0.
5631 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5632 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5633 struct sched_group
**sg
))
5635 struct sched_group
*first
= NULL
, *last
= NULL
;
5636 cpumask_t covered
= CPU_MASK_NONE
;
5639 for_each_cpu_mask(i
, span
) {
5640 struct sched_group
*sg
;
5641 int group
= group_fn(i
, cpu_map
, &sg
);
5644 if (cpu_isset(i
, covered
))
5647 sg
->cpumask
= CPU_MASK_NONE
;
5650 for_each_cpu_mask(j
, span
) {
5651 if (group_fn(j
, cpu_map
, NULL
) != group
)
5654 cpu_set(j
, covered
);
5655 cpu_set(j
, sg
->cpumask
);
5666 #define SD_NODES_PER_DOMAIN 16
5669 * Self-tuning task migration cost measurement between source and target CPUs.
5671 * This is done by measuring the cost of manipulating buffers of varying
5672 * sizes. For a given buffer-size here are the steps that are taken:
5674 * 1) the source CPU reads+dirties a shared buffer
5675 * 2) the target CPU reads+dirties the same shared buffer
5677 * We measure how long they take, in the following 4 scenarios:
5679 * - source: CPU1, target: CPU2 | cost1
5680 * - source: CPU2, target: CPU1 | cost2
5681 * - source: CPU1, target: CPU1 | cost3
5682 * - source: CPU2, target: CPU2 | cost4
5684 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5685 * the cost of migration.
5687 * We then start off from a small buffer-size and iterate up to larger
5688 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5689 * doing a maximum search for the cost. (The maximum cost for a migration
5690 * normally occurs when the working set size is around the effective cache
5693 #define SEARCH_SCOPE 2
5694 #define MIN_CACHE_SIZE (64*1024U)
5695 #define DEFAULT_CACHE_SIZE (5*1024*1024U)
5696 #define ITERATIONS 1
5697 #define SIZE_THRESH 130
5698 #define COST_THRESH 130
5701 * The migration cost is a function of 'domain distance'. Domain
5702 * distance is the number of steps a CPU has to iterate down its
5703 * domain tree to share a domain with the other CPU. The farther
5704 * two CPUs are from each other, the larger the distance gets.
5706 * Note that we use the distance only to cache measurement results,
5707 * the distance value is not used numerically otherwise. When two
5708 * CPUs have the same distance it is assumed that the migration
5709 * cost is the same. (this is a simplification but quite practical)
5711 #define MAX_DOMAIN_DISTANCE 32
5713 static unsigned long long migration_cost
[MAX_DOMAIN_DISTANCE
] =
5714 { [ 0 ... MAX_DOMAIN_DISTANCE
-1 ] =
5716 * Architectures may override the migration cost and thus avoid
5717 * boot-time calibration. Unit is nanoseconds. Mostly useful for
5718 * virtualized hardware:
5720 #ifdef CONFIG_DEFAULT_MIGRATION_COST
5721 CONFIG_DEFAULT_MIGRATION_COST
5728 * Allow override of migration cost - in units of microseconds.
5729 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5730 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5732 static int __init
migration_cost_setup(char *str
)
5734 int ints
[MAX_DOMAIN_DISTANCE
+1], i
;
5736 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5738 printk("#ints: %d\n", ints
[0]);
5739 for (i
= 1; i
<= ints
[0]; i
++) {
5740 migration_cost
[i
-1] = (unsigned long long)ints
[i
]*1000;
5741 printk("migration_cost[%d]: %Ld\n", i
-1, migration_cost
[i
-1]);
5746 __setup ("migration_cost=", migration_cost_setup
);
5749 * Global multiplier (divisor) for migration-cutoff values,
5750 * in percentiles. E.g. use a value of 150 to get 1.5 times
5751 * longer cache-hot cutoff times.
5753 * (We scale it from 100 to 128 to long long handling easier.)
5756 #define MIGRATION_FACTOR_SCALE 128
5758 static unsigned int migration_factor
= MIGRATION_FACTOR_SCALE
;
5760 static int __init
setup_migration_factor(char *str
)
5762 get_option(&str
, &migration_factor
);
5763 migration_factor
= migration_factor
* MIGRATION_FACTOR_SCALE
/ 100;
5767 __setup("migration_factor=", setup_migration_factor
);
5770 * Estimated distance of two CPUs, measured via the number of domains
5771 * we have to pass for the two CPUs to be in the same span:
5773 static unsigned long domain_distance(int cpu1
, int cpu2
)
5775 unsigned long distance
= 0;
5776 struct sched_domain
*sd
;
5778 for_each_domain(cpu1
, sd
) {
5779 WARN_ON(!cpu_isset(cpu1
, sd
->span
));
5780 if (cpu_isset(cpu2
, sd
->span
))
5784 if (distance
>= MAX_DOMAIN_DISTANCE
) {
5786 distance
= MAX_DOMAIN_DISTANCE
-1;
5792 static unsigned int migration_debug
;
5794 static int __init
setup_migration_debug(char *str
)
5796 get_option(&str
, &migration_debug
);
5800 __setup("migration_debug=", setup_migration_debug
);
5803 * Maximum cache-size that the scheduler should try to measure.
5804 * Architectures with larger caches should tune this up during
5805 * bootup. Gets used in the domain-setup code (i.e. during SMP
5808 unsigned int max_cache_size
;
5810 static int __init
setup_max_cache_size(char *str
)
5812 get_option(&str
, &max_cache_size
);
5816 __setup("max_cache_size=", setup_max_cache_size
);
5819 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5820 * is the operation that is timed, so we try to generate unpredictable
5821 * cachemisses that still end up filling the L2 cache:
5823 static void touch_cache(void *__cache
, unsigned long __size
)
5825 unsigned long size
= __size
/ sizeof(long);
5826 unsigned long chunk1
= size
/ 3;
5827 unsigned long chunk2
= 2 * size
/ 3;
5828 unsigned long *cache
= __cache
;
5831 for (i
= 0; i
< size
/6; i
+= 8) {
5834 case 1: cache
[size
-1-i
]++;
5835 case 2: cache
[chunk1
-i
]++;
5836 case 3: cache
[chunk1
+i
]++;
5837 case 4: cache
[chunk2
-i
]++;
5838 case 5: cache
[chunk2
+i
]++;
5844 * Measure the cache-cost of one task migration. Returns in units of nsec.
5846 static unsigned long long
5847 measure_one(void *cache
, unsigned long size
, int source
, int target
)
5849 cpumask_t mask
, saved_mask
;
5850 unsigned long long t0
, t1
, t2
, t3
, cost
;
5852 saved_mask
= current
->cpus_allowed
;
5855 * Flush source caches to RAM and invalidate them:
5860 * Migrate to the source CPU:
5862 mask
= cpumask_of_cpu(source
);
5863 set_cpus_allowed(current
, mask
);
5864 WARN_ON(smp_processor_id() != source
);
5867 * Dirty the working set:
5870 touch_cache(cache
, size
);
5874 * Migrate to the target CPU, dirty the L2 cache and access
5875 * the shared buffer. (which represents the working set
5876 * of a migrated task.)
5878 mask
= cpumask_of_cpu(target
);
5879 set_cpus_allowed(current
, mask
);
5880 WARN_ON(smp_processor_id() != target
);
5883 touch_cache(cache
, size
);
5886 cost
= t1
-t0
+ t3
-t2
;
5888 if (migration_debug
>= 2)
5889 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5890 source
, target
, t1
-t0
, t1
-t0
, t3
-t2
, cost
);
5892 * Flush target caches to RAM and invalidate them:
5896 set_cpus_allowed(current
, saved_mask
);
5902 * Measure a series of task migrations and return the average
5903 * result. Since this code runs early during bootup the system
5904 * is 'undisturbed' and the average latency makes sense.
5906 * The algorithm in essence auto-detects the relevant cache-size,
5907 * so it will properly detect different cachesizes for different
5908 * cache-hierarchies, depending on how the CPUs are connected.
5910 * Architectures can prime the upper limit of the search range via
5911 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5913 static unsigned long long
5914 measure_cost(int cpu1
, int cpu2
, void *cache
, unsigned int size
)
5916 unsigned long long cost1
, cost2
;
5920 * Measure the migration cost of 'size' bytes, over an
5921 * average of 10 runs:
5923 * (We perturb the cache size by a small (0..4k)
5924 * value to compensate size/alignment related artifacts.
5925 * We also subtract the cost of the operation done on
5931 * dry run, to make sure we start off cache-cold on cpu1,
5932 * and to get any vmalloc pagefaults in advance:
5934 measure_one(cache
, size
, cpu1
, cpu2
);
5935 for (i
= 0; i
< ITERATIONS
; i
++)
5936 cost1
+= measure_one(cache
, size
- i
* 1024, cpu1
, cpu2
);
5938 measure_one(cache
, size
, cpu2
, cpu1
);
5939 for (i
= 0; i
< ITERATIONS
; i
++)
5940 cost1
+= measure_one(cache
, size
- i
* 1024, cpu2
, cpu1
);
5943 * (We measure the non-migrating [cached] cost on both
5944 * cpu1 and cpu2, to handle CPUs with different speeds)
5948 measure_one(cache
, size
, cpu1
, cpu1
);
5949 for (i
= 0; i
< ITERATIONS
; i
++)
5950 cost2
+= measure_one(cache
, size
- i
* 1024, cpu1
, cpu1
);
5952 measure_one(cache
, size
, cpu2
, cpu2
);
5953 for (i
= 0; i
< ITERATIONS
; i
++)
5954 cost2
+= measure_one(cache
, size
- i
* 1024, cpu2
, cpu2
);
5957 * Get the per-iteration migration cost:
5959 do_div(cost1
, 2 * ITERATIONS
);
5960 do_div(cost2
, 2 * ITERATIONS
);
5962 return cost1
- cost2
;
5965 static unsigned long long measure_migration_cost(int cpu1
, int cpu2
)
5967 unsigned long long max_cost
= 0, fluct
= 0, avg_fluct
= 0;
5968 unsigned int max_size
, size
, size_found
= 0;
5969 long long cost
= 0, prev_cost
;
5973 * Search from max_cache_size*5 down to 64K - the real relevant
5974 * cachesize has to lie somewhere inbetween.
5976 if (max_cache_size
) {
5977 max_size
= max(max_cache_size
* SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5978 size
= max(max_cache_size
/ SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5981 * Since we have no estimation about the relevant
5984 max_size
= DEFAULT_CACHE_SIZE
* SEARCH_SCOPE
;
5985 size
= MIN_CACHE_SIZE
;
5988 if (!cpu_online(cpu1
) || !cpu_online(cpu2
)) {
5989 printk("cpu %d and %d not both online!\n", cpu1
, cpu2
);
5994 * Allocate the working set:
5996 cache
= vmalloc(max_size
);
5998 printk("could not vmalloc %d bytes for cache!\n", 2 * max_size
);
5999 return 1000000; /* return 1 msec on very small boxen */
6002 while (size
<= max_size
) {
6004 cost
= measure_cost(cpu1
, cpu2
, cache
, size
);
6010 if (max_cost
< cost
) {
6016 * Calculate average fluctuation, we use this to prevent
6017 * noise from triggering an early break out of the loop:
6019 fluct
= abs(cost
- prev_cost
);
6020 avg_fluct
= (avg_fluct
+ fluct
)/2;
6022 if (migration_debug
)
6023 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): "
6026 (long)cost
/ 1000000,
6027 ((long)cost
/ 100000) % 10,
6028 (long)max_cost
/ 1000000,
6029 ((long)max_cost
/ 100000) % 10,
6030 domain_distance(cpu1
, cpu2
),
6034 * If we iterated at least 20% past the previous maximum,
6035 * and the cost has dropped by more than 20% already,
6036 * (taking fluctuations into account) then we assume to
6037 * have found the maximum and break out of the loop early:
6039 if (size_found
&& (size
*100 > size_found
*SIZE_THRESH
))
6040 if (cost
+avg_fluct
<= 0 ||
6041 max_cost
*100 > (cost
+avg_fluct
)*COST_THRESH
) {
6043 if (migration_debug
)
6044 printk("-> found max.\n");
6048 * Increase the cachesize in 10% steps:
6050 size
= size
* 10 / 9;
6053 if (migration_debug
)
6054 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
6055 cpu1
, cpu2
, size_found
, max_cost
);
6060 * A task is considered 'cache cold' if at least 2 times
6061 * the worst-case cost of migration has passed.
6063 * (this limit is only listened to if the load-balancing
6064 * situation is 'nice' - if there is a large imbalance we
6065 * ignore it for the sake of CPU utilization and
6066 * processing fairness.)
6068 return 2 * max_cost
* migration_factor
/ MIGRATION_FACTOR_SCALE
;
6071 static void calibrate_migration_costs(const cpumask_t
*cpu_map
)
6073 int cpu1
= -1, cpu2
= -1, cpu
, orig_cpu
= raw_smp_processor_id();
6074 unsigned long j0
, j1
, distance
, max_distance
= 0;
6075 struct sched_domain
*sd
;
6080 * First pass - calculate the cacheflush times:
6082 for_each_cpu_mask(cpu1
, *cpu_map
) {
6083 for_each_cpu_mask(cpu2
, *cpu_map
) {
6086 distance
= domain_distance(cpu1
, cpu2
);
6087 max_distance
= max(max_distance
, distance
);
6089 * No result cached yet?
6091 if (migration_cost
[distance
] == -1LL)
6092 migration_cost
[distance
] =
6093 measure_migration_cost(cpu1
, cpu2
);
6097 * Second pass - update the sched domain hierarchy with
6098 * the new cache-hot-time estimations:
6100 for_each_cpu_mask(cpu
, *cpu_map
) {
6102 for_each_domain(cpu
, sd
) {
6103 sd
->cache_hot_time
= migration_cost
[distance
];
6110 if (migration_debug
)
6111 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
6119 if (system_state
== SYSTEM_BOOTING
&& num_online_cpus() > 1) {
6120 printk("migration_cost=");
6121 for (distance
= 0; distance
<= max_distance
; distance
++) {
6124 printk("%ld", (long)migration_cost
[distance
] / 1000);
6129 if (migration_debug
)
6130 printk("migration: %ld seconds\n", (j1
-j0
) / HZ
);
6133 * Move back to the original CPU. NUMA-Q gets confused
6134 * if we migrate to another quad during bootup.
6136 if (raw_smp_processor_id() != orig_cpu
) {
6137 cpumask_t mask
= cpumask_of_cpu(orig_cpu
),
6138 saved_mask
= current
->cpus_allowed
;
6140 set_cpus_allowed(current
, mask
);
6141 set_cpus_allowed(current
, saved_mask
);
6148 * find_next_best_node - find the next node to include in a sched_domain
6149 * @node: node whose sched_domain we're building
6150 * @used_nodes: nodes already in the sched_domain
6152 * Find the next node to include in a given scheduling domain. Simply
6153 * finds the closest node not already in the @used_nodes map.
6155 * Should use nodemask_t.
6157 static int find_next_best_node(int node
, unsigned long *used_nodes
)
6159 int i
, n
, val
, min_val
, best_node
= 0;
6163 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6164 /* Start at @node */
6165 n
= (node
+ i
) % MAX_NUMNODES
;
6167 if (!nr_cpus_node(n
))
6170 /* Skip already used nodes */
6171 if (test_bit(n
, used_nodes
))
6174 /* Simple min distance search */
6175 val
= node_distance(node
, n
);
6177 if (val
< min_val
) {
6183 set_bit(best_node
, used_nodes
);
6188 * sched_domain_node_span - get a cpumask for a node's sched_domain
6189 * @node: node whose cpumask we're constructing
6190 * @size: number of nodes to include in this span
6192 * Given a node, construct a good cpumask for its sched_domain to span. It
6193 * should be one that prevents unnecessary balancing, but also spreads tasks
6196 static cpumask_t
sched_domain_node_span(int node
)
6198 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
6199 cpumask_t span
, nodemask
;
6203 bitmap_zero(used_nodes
, MAX_NUMNODES
);
6205 nodemask
= node_to_cpumask(node
);
6206 cpus_or(span
, span
, nodemask
);
6207 set_bit(node
, used_nodes
);
6209 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6210 int next_node
= find_next_best_node(node
, used_nodes
);
6212 nodemask
= node_to_cpumask(next_node
);
6213 cpus_or(span
, span
, nodemask
);
6220 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
6223 * SMT sched-domains:
6225 #ifdef CONFIG_SCHED_SMT
6226 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
6227 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6229 static int cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
,
6230 struct sched_group
**sg
)
6233 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6239 * multi-core sched-domains:
6241 #ifdef CONFIG_SCHED_MC
6242 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6243 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6246 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6247 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6248 struct sched_group
**sg
)
6251 cpumask_t mask
= cpu_sibling_map
[cpu
];
6252 cpus_and(mask
, mask
, *cpu_map
);
6253 group
= first_cpu(mask
);
6255 *sg
= &per_cpu(sched_group_core
, group
);
6258 #elif defined(CONFIG_SCHED_MC)
6259 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6260 struct sched_group
**sg
)
6263 *sg
= &per_cpu(sched_group_core
, cpu
);
6268 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6269 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6271 static int cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
,
6272 struct sched_group
**sg
)
6275 #ifdef CONFIG_SCHED_MC
6276 cpumask_t mask
= cpu_coregroup_map(cpu
);
6277 cpus_and(mask
, mask
, *cpu_map
);
6278 group
= first_cpu(mask
);
6279 #elif defined(CONFIG_SCHED_SMT)
6280 cpumask_t mask
= cpu_sibling_map
[cpu
];
6281 cpus_and(mask
, mask
, *cpu_map
);
6282 group
= first_cpu(mask
);
6287 *sg
= &per_cpu(sched_group_phys
, group
);
6293 * The init_sched_build_groups can't handle what we want to do with node
6294 * groups, so roll our own. Now each node has its own list of groups which
6295 * gets dynamically allocated.
6297 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6298 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6300 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6301 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6303 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6304 struct sched_group
**sg
)
6306 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6309 cpus_and(nodemask
, nodemask
, *cpu_map
);
6310 group
= first_cpu(nodemask
);
6313 *sg
= &per_cpu(sched_group_allnodes
, group
);
6317 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6319 struct sched_group
*sg
= group_head
;
6325 for_each_cpu_mask(j
, sg
->cpumask
) {
6326 struct sched_domain
*sd
;
6328 sd
= &per_cpu(phys_domains
, j
);
6329 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6331 * Only add "power" once for each
6337 sg
->cpu_power
+= sd
->groups
->cpu_power
;
6340 if (sg
!= group_head
)
6346 /* Free memory allocated for various sched_group structures */
6347 static void free_sched_groups(const cpumask_t
*cpu_map
)
6351 for_each_cpu_mask(cpu
, *cpu_map
) {
6352 struct sched_group
**sched_group_nodes
6353 = sched_group_nodes_bycpu
[cpu
];
6355 if (!sched_group_nodes
)
6358 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6359 cpumask_t nodemask
= node_to_cpumask(i
);
6360 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6362 cpus_and(nodemask
, nodemask
, *cpu_map
);
6363 if (cpus_empty(nodemask
))
6373 if (oldsg
!= sched_group_nodes
[i
])
6376 kfree(sched_group_nodes
);
6377 sched_group_nodes_bycpu
[cpu
] = NULL
;
6381 static void free_sched_groups(const cpumask_t
*cpu_map
)
6387 * Initialize sched groups cpu_power.
6389 * cpu_power indicates the capacity of sched group, which is used while
6390 * distributing the load between different sched groups in a sched domain.
6391 * Typically cpu_power for all the groups in a sched domain will be same unless
6392 * there are asymmetries in the topology. If there are asymmetries, group
6393 * having more cpu_power will pickup more load compared to the group having
6396 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6397 * the maximum number of tasks a group can handle in the presence of other idle
6398 * or lightly loaded groups in the same sched domain.
6400 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6402 struct sched_domain
*child
;
6403 struct sched_group
*group
;
6405 WARN_ON(!sd
|| !sd
->groups
);
6407 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6413 * For perf policy, if the groups in child domain share resources
6414 * (for example cores sharing some portions of the cache hierarchy
6415 * or SMT), then set this domain groups cpu_power such that each group
6416 * can handle only one task, when there are other idle groups in the
6417 * same sched domain.
6419 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6421 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6422 sd
->groups
->cpu_power
= SCHED_LOAD_SCALE
;
6426 sd
->groups
->cpu_power
= 0;
6429 * add cpu_power of each child group to this groups cpu_power
6431 group
= child
->groups
;
6433 sd
->groups
->cpu_power
+= group
->cpu_power
;
6434 group
= group
->next
;
6435 } while (group
!= child
->groups
);
6439 * Build sched domains for a given set of cpus and attach the sched domains
6440 * to the individual cpus
6442 static int build_sched_domains(const cpumask_t
*cpu_map
)
6445 struct sched_domain
*sd
;
6447 struct sched_group
**sched_group_nodes
= NULL
;
6448 int sd_allnodes
= 0;
6451 * Allocate the per-node list of sched groups
6453 sched_group_nodes
= kzalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
6455 if (!sched_group_nodes
) {
6456 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6459 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6463 * Set up domains for cpus specified by the cpu_map.
6465 for_each_cpu_mask(i
, *cpu_map
) {
6466 struct sched_domain
*sd
= NULL
, *p
;
6467 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6469 cpus_and(nodemask
, nodemask
, *cpu_map
);
6472 if (cpus_weight(*cpu_map
)
6473 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6474 sd
= &per_cpu(allnodes_domains
, i
);
6475 *sd
= SD_ALLNODES_INIT
;
6476 sd
->span
= *cpu_map
;
6477 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6483 sd
= &per_cpu(node_domains
, i
);
6485 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6489 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6493 sd
= &per_cpu(phys_domains
, i
);
6495 sd
->span
= nodemask
;
6499 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6501 #ifdef CONFIG_SCHED_MC
6503 sd
= &per_cpu(core_domains
, i
);
6505 sd
->span
= cpu_coregroup_map(i
);
6506 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6509 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6512 #ifdef CONFIG_SCHED_SMT
6514 sd
= &per_cpu(cpu_domains
, i
);
6515 *sd
= SD_SIBLING_INIT
;
6516 sd
->span
= cpu_sibling_map
[i
];
6517 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6520 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6524 #ifdef CONFIG_SCHED_SMT
6525 /* Set up CPU (sibling) groups */
6526 for_each_cpu_mask(i
, *cpu_map
) {
6527 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
6528 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6529 if (i
!= first_cpu(this_sibling_map
))
6532 init_sched_build_groups(this_sibling_map
, cpu_map
, &cpu_to_cpu_group
);
6536 #ifdef CONFIG_SCHED_MC
6537 /* Set up multi-core groups */
6538 for_each_cpu_mask(i
, *cpu_map
) {
6539 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6540 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6541 if (i
!= first_cpu(this_core_map
))
6543 init_sched_build_groups(this_core_map
, cpu_map
, &cpu_to_core_group
);
6548 /* Set up physical groups */
6549 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6550 cpumask_t nodemask
= node_to_cpumask(i
);
6552 cpus_and(nodemask
, nodemask
, *cpu_map
);
6553 if (cpus_empty(nodemask
))
6556 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6560 /* Set up node groups */
6562 init_sched_build_groups(*cpu_map
, cpu_map
, &cpu_to_allnodes_group
);
6564 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6565 /* Set up node groups */
6566 struct sched_group
*sg
, *prev
;
6567 cpumask_t nodemask
= node_to_cpumask(i
);
6568 cpumask_t domainspan
;
6569 cpumask_t covered
= CPU_MASK_NONE
;
6572 cpus_and(nodemask
, nodemask
, *cpu_map
);
6573 if (cpus_empty(nodemask
)) {
6574 sched_group_nodes
[i
] = NULL
;
6578 domainspan
= sched_domain_node_span(i
);
6579 cpus_and(domainspan
, domainspan
, *cpu_map
);
6581 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6583 printk(KERN_WARNING
"Can not alloc domain group for "
6587 sched_group_nodes
[i
] = sg
;
6588 for_each_cpu_mask(j
, nodemask
) {
6589 struct sched_domain
*sd
;
6590 sd
= &per_cpu(node_domains
, j
);
6594 sg
->cpumask
= nodemask
;
6596 cpus_or(covered
, covered
, nodemask
);
6599 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6600 cpumask_t tmp
, notcovered
;
6601 int n
= (i
+ j
) % MAX_NUMNODES
;
6603 cpus_complement(notcovered
, covered
);
6604 cpus_and(tmp
, notcovered
, *cpu_map
);
6605 cpus_and(tmp
, tmp
, domainspan
);
6606 if (cpus_empty(tmp
))
6609 nodemask
= node_to_cpumask(n
);
6610 cpus_and(tmp
, tmp
, nodemask
);
6611 if (cpus_empty(tmp
))
6614 sg
= kmalloc_node(sizeof(struct sched_group
),
6618 "Can not alloc domain group for node %d\n", j
);
6623 sg
->next
= prev
->next
;
6624 cpus_or(covered
, covered
, tmp
);
6631 /* Calculate CPU power for physical packages and nodes */
6632 #ifdef CONFIG_SCHED_SMT
6633 for_each_cpu_mask(i
, *cpu_map
) {
6634 sd
= &per_cpu(cpu_domains
, i
);
6635 init_sched_groups_power(i
, sd
);
6638 #ifdef CONFIG_SCHED_MC
6639 for_each_cpu_mask(i
, *cpu_map
) {
6640 sd
= &per_cpu(core_domains
, i
);
6641 init_sched_groups_power(i
, sd
);
6645 for_each_cpu_mask(i
, *cpu_map
) {
6646 sd
= &per_cpu(phys_domains
, i
);
6647 init_sched_groups_power(i
, sd
);
6651 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6652 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6655 struct sched_group
*sg
;
6657 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6658 init_numa_sched_groups_power(sg
);
6662 /* Attach the domains */
6663 for_each_cpu_mask(i
, *cpu_map
) {
6664 struct sched_domain
*sd
;
6665 #ifdef CONFIG_SCHED_SMT
6666 sd
= &per_cpu(cpu_domains
, i
);
6667 #elif defined(CONFIG_SCHED_MC)
6668 sd
= &per_cpu(core_domains
, i
);
6670 sd
= &per_cpu(phys_domains
, i
);
6672 cpu_attach_domain(sd
, i
);
6675 * Tune cache-hot values:
6677 calibrate_migration_costs(cpu_map
);
6683 free_sched_groups(cpu_map
);
6688 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6690 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6692 cpumask_t cpu_default_map
;
6696 * Setup mask for cpus without special case scheduling requirements.
6697 * For now this just excludes isolated cpus, but could be used to
6698 * exclude other special cases in the future.
6700 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
6702 err
= build_sched_domains(&cpu_default_map
);
6707 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6709 free_sched_groups(cpu_map
);
6713 * Detach sched domains from a group of cpus specified in cpu_map
6714 * These cpus will now be attached to the NULL domain
6716 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6720 for_each_cpu_mask(i
, *cpu_map
)
6721 cpu_attach_domain(NULL
, i
);
6722 synchronize_sched();
6723 arch_destroy_sched_domains(cpu_map
);
6727 * Partition sched domains as specified by the cpumasks below.
6728 * This attaches all cpus from the cpumasks to the NULL domain,
6729 * waits for a RCU quiescent period, recalculates sched
6730 * domain information and then attaches them back to the
6731 * correct sched domains
6732 * Call with hotplug lock held
6734 int partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
6736 cpumask_t change_map
;
6739 cpus_and(*partition1
, *partition1
, cpu_online_map
);
6740 cpus_and(*partition2
, *partition2
, cpu_online_map
);
6741 cpus_or(change_map
, *partition1
, *partition2
);
6743 /* Detach sched domains from all of the affected cpus */
6744 detach_destroy_domains(&change_map
);
6745 if (!cpus_empty(*partition1
))
6746 err
= build_sched_domains(partition1
);
6747 if (!err
&& !cpus_empty(*partition2
))
6748 err
= build_sched_domains(partition2
);
6753 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6754 int arch_reinit_sched_domains(void)
6759 detach_destroy_domains(&cpu_online_map
);
6760 err
= arch_init_sched_domains(&cpu_online_map
);
6761 unlock_cpu_hotplug();
6766 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6770 if (buf
[0] != '0' && buf
[0] != '1')
6774 sched_smt_power_savings
= (buf
[0] == '1');
6776 sched_mc_power_savings
= (buf
[0] == '1');
6778 ret
= arch_reinit_sched_domains();
6780 return ret
? ret
: count
;
6783 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6787 #ifdef CONFIG_SCHED_SMT
6789 err
= sysfs_create_file(&cls
->kset
.kobj
,
6790 &attr_sched_smt_power_savings
.attr
);
6792 #ifdef CONFIG_SCHED_MC
6793 if (!err
&& mc_capable())
6794 err
= sysfs_create_file(&cls
->kset
.kobj
,
6795 &attr_sched_mc_power_savings
.attr
);
6801 #ifdef CONFIG_SCHED_MC
6802 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6804 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6806 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6807 const char *buf
, size_t count
)
6809 return sched_power_savings_store(buf
, count
, 0);
6811 SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6812 sched_mc_power_savings_store
);
6815 #ifdef CONFIG_SCHED_SMT
6816 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6818 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6820 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6821 const char *buf
, size_t count
)
6823 return sched_power_savings_store(buf
, count
, 1);
6825 SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6826 sched_smt_power_savings_store
);
6830 * Force a reinitialization of the sched domains hierarchy. The domains
6831 * and groups cannot be updated in place without racing with the balancing
6832 * code, so we temporarily attach all running cpus to the NULL domain
6833 * which will prevent rebalancing while the sched domains are recalculated.
6835 static int update_sched_domains(struct notifier_block
*nfb
,
6836 unsigned long action
, void *hcpu
)
6839 case CPU_UP_PREPARE
:
6840 case CPU_DOWN_PREPARE
:
6841 detach_destroy_domains(&cpu_online_map
);
6844 case CPU_UP_CANCELED
:
6845 case CPU_DOWN_FAILED
:
6849 * Fall through and re-initialise the domains.
6856 /* The hotplug lock is already held by cpu_up/cpu_down */
6857 arch_init_sched_domains(&cpu_online_map
);
6862 void __init
sched_init_smp(void)
6864 cpumask_t non_isolated_cpus
;
6867 arch_init_sched_domains(&cpu_online_map
);
6868 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6869 if (cpus_empty(non_isolated_cpus
))
6870 cpu_set(smp_processor_id(), non_isolated_cpus
);
6871 unlock_cpu_hotplug();
6872 /* XXX: Theoretical race here - CPU may be hotplugged now */
6873 hotcpu_notifier(update_sched_domains
, 0);
6875 /* Move init over to a non-isolated CPU */
6876 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6880 void __init
sched_init_smp(void)
6883 #endif /* CONFIG_SMP */
6885 int in_sched_functions(unsigned long addr
)
6887 /* Linker adds these: start and end of __sched functions */
6888 extern char __sched_text_start
[], __sched_text_end
[];
6890 return in_lock_functions(addr
) ||
6891 (addr
>= (unsigned long)__sched_text_start
6892 && addr
< (unsigned long)__sched_text_end
);
6895 void __init
sched_init(void)
6899 for_each_possible_cpu(i
) {
6900 struct prio_array
*array
;
6904 spin_lock_init(&rq
->lock
);
6905 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6907 rq
->active
= rq
->arrays
;
6908 rq
->expired
= rq
->arrays
+ 1;
6909 rq
->best_expired_prio
= MAX_PRIO
;
6913 for (j
= 1; j
< 3; j
++)
6914 rq
->cpu_load
[j
] = 0;
6915 rq
->active_balance
= 0;
6918 rq
->migration_thread
= NULL
;
6919 INIT_LIST_HEAD(&rq
->migration_queue
);
6921 atomic_set(&rq
->nr_iowait
, 0);
6923 for (j
= 0; j
< 2; j
++) {
6924 array
= rq
->arrays
+ j
;
6925 for (k
= 0; k
< MAX_PRIO
; k
++) {
6926 INIT_LIST_HEAD(array
->queue
+ k
);
6927 __clear_bit(k
, array
->bitmap
);
6929 // delimiter for bitsearch
6930 __set_bit(MAX_PRIO
, array
->bitmap
);
6934 set_load_weight(&init_task
);
6937 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6940 #ifdef CONFIG_RT_MUTEXES
6941 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6945 * The boot idle thread does lazy MMU switching as well:
6947 atomic_inc(&init_mm
.mm_count
);
6948 enter_lazy_tlb(&init_mm
, current
);
6951 * Make us the idle thread. Technically, schedule() should not be
6952 * called from this thread, however somewhere below it might be,
6953 * but because we are the idle thread, we just pick up running again
6954 * when this runqueue becomes "idle".
6956 init_idle(current
, smp_processor_id());
6959 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6960 void __might_sleep(char *file
, int line
)
6963 static unsigned long prev_jiffy
; /* ratelimiting */
6965 if ((in_atomic() || irqs_disabled()) &&
6966 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6967 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6969 prev_jiffy
= jiffies
;
6970 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6971 " context at %s:%d\n", file
, line
);
6972 printk("in_atomic():%d, irqs_disabled():%d\n",
6973 in_atomic(), irqs_disabled());
6974 debug_show_held_locks(current
);
6975 if (irqs_disabled())
6976 print_irqtrace_events(current
);
6981 EXPORT_SYMBOL(__might_sleep
);
6984 #ifdef CONFIG_MAGIC_SYSRQ
6985 void normalize_rt_tasks(void)
6987 struct prio_array
*array
;
6988 struct task_struct
*p
;
6989 unsigned long flags
;
6992 read_lock_irq(&tasklist_lock
);
6993 for_each_process(p
) {
6997 spin_lock_irqsave(&p
->pi_lock
, flags
);
6998 rq
= __task_rq_lock(p
);
7002 deactivate_task(p
, task_rq(p
));
7003 __setscheduler(p
, SCHED_NORMAL
, 0);
7005 __activate_task(p
, task_rq(p
));
7006 resched_task(rq
->curr
);
7009 __task_rq_unlock(rq
);
7010 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
7012 read_unlock_irq(&tasklist_lock
);
7015 #endif /* CONFIG_MAGIC_SYSRQ */
7019 * These functions are only useful for the IA64 MCA handling.
7021 * They can only be called when the whole system has been
7022 * stopped - every CPU needs to be quiescent, and no scheduling
7023 * activity can take place. Using them for anything else would
7024 * be a serious bug, and as a result, they aren't even visible
7025 * under any other configuration.
7029 * curr_task - return the current task for a given cpu.
7030 * @cpu: the processor in question.
7032 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7034 struct task_struct
*curr_task(int cpu
)
7036 return cpu_curr(cpu
);
7040 * set_curr_task - set the current task for a given cpu.
7041 * @cpu: the processor in question.
7042 * @p: the task pointer to set.
7044 * Description: This function must only be used when non-maskable interrupts
7045 * are serviced on a separate stack. It allows the architecture to switch the
7046 * notion of the current task on a cpu in a non-blocking manner. This function
7047 * must be called with all CPU's synchronized, and interrupts disabled, the
7048 * and caller must save the original value of the current task (see
7049 * curr_task() above) and restore that value before reenabling interrupts and
7050 * re-starting the system.
7052 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7054 void set_curr_task(int cpu
, struct task_struct
*p
)