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 * Scheduler clock - returns current time in nanosec units.
61 * This is default implementation.
62 * Architectures and sub-architectures can override this.
64 unsigned long long __attribute__((weak
)) sched_clock(void)
66 return (unsigned long long)jiffies
* (1000000000 / HZ
);
70 * Convert user-nice values [ -20 ... 0 ... 19 ]
71 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
74 #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
75 #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
76 #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
79 * 'User priority' is the nice value converted to something we
80 * can work with better when scaling various scheduler parameters,
81 * it's a [ 0 ... 39 ] range.
83 #define USER_PRIO(p) ((p)-MAX_RT_PRIO)
84 #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
85 #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
88 * Some helpers for converting nanosecond timing to jiffy resolution
90 #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ))
91 #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))
94 * These are the 'tuning knobs' of the scheduler:
96 * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger),
97 * default timeslice is 100 msecs, maximum timeslice is 800 msecs.
98 * Timeslices get refilled after they expire.
100 #define MIN_TIMESLICE max(5 * HZ / 1000, 1)
101 #define DEF_TIMESLICE (100 * HZ / 1000)
102 #define ON_RUNQUEUE_WEIGHT 30
103 #define CHILD_PENALTY 95
104 #define PARENT_PENALTY 100
105 #define EXIT_WEIGHT 3
106 #define PRIO_BONUS_RATIO 25
107 #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
108 #define INTERACTIVE_DELTA 2
109 #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
110 #define STARVATION_LIMIT (MAX_SLEEP_AVG)
111 #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
114 * If a task is 'interactive' then we reinsert it in the active
115 * array after it has expired its current timeslice. (it will not
116 * continue to run immediately, it will still roundrobin with
117 * other interactive tasks.)
119 * This part scales the interactivity limit depending on niceness.
121 * We scale it linearly, offset by the INTERACTIVE_DELTA delta.
122 * Here are a few examples of different nice levels:
124 * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0]
125 * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0]
126 * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0]
127 * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0]
128 * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0]
130 * (the X axis represents the possible -5 ... 0 ... +5 dynamic
131 * priority range a task can explore, a value of '1' means the
132 * task is rated interactive.)
134 * Ie. nice +19 tasks can never get 'interactive' enough to be
135 * reinserted into the active array. And only heavily CPU-hog nice -20
136 * tasks will be expired. Default nice 0 tasks are somewhere between,
137 * it takes some effort for them to get interactive, but it's not
141 #define CURRENT_BONUS(p) \
142 (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \
145 #define GRANULARITY (10 * HZ / 1000 ? : 1)
148 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
149 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \
152 #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \
153 (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)))
156 #define SCALE(v1,v1_max,v2_max) \
157 (v1) * (v2_max) / (v1_max)
160 (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
163 #define TASK_INTERACTIVE(p) \
164 ((p)->prio <= (p)->static_prio - DELTA(p))
166 #define INTERACTIVE_SLEEP(p) \
167 (JIFFIES_TO_NS(MAX_SLEEP_AVG * \
168 (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1))
170 #define TASK_PREEMPTS_CURR(p, rq) \
171 ((p)->prio < (rq)->curr->prio)
173 #define SCALE_PRIO(x, prio) \
174 max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE)
176 static unsigned int static_prio_timeslice(int static_prio
)
178 if (static_prio
< NICE_TO_PRIO(0))
179 return SCALE_PRIO(DEF_TIMESLICE
* 4, static_prio
);
181 return SCALE_PRIO(DEF_TIMESLICE
, static_prio
);
185 * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ]
186 * to time slice values: [800ms ... 100ms ... 5ms]
188 * The higher a thread's priority, the bigger timeslices
189 * it gets during one round of execution. But even the lowest
190 * priority thread gets MIN_TIMESLICE worth of execution time.
193 static inline unsigned int task_timeslice(struct task_struct
*p
)
195 return static_prio_timeslice(p
->static_prio
);
199 * These are the runqueue data structures:
203 unsigned int nr_active
;
204 DECLARE_BITMAP(bitmap
, MAX_PRIO
+1); /* include 1 bit for delimiter */
205 struct list_head queue
[MAX_PRIO
];
209 * This is the main, per-CPU runqueue data structure.
211 * Locking rule: those places that want to lock multiple runqueues
212 * (such as the load balancing or the thread migration code), lock
213 * acquire operations must be ordered by ascending &runqueue.
219 * nr_running and cpu_load should be in the same cacheline because
220 * remote CPUs use both these fields when doing load calculation.
222 unsigned long nr_running
;
223 unsigned long raw_weighted_load
;
225 unsigned long cpu_load
[3];
227 unsigned long long nr_switches
;
230 * This is part of a global counter where only the total sum
231 * over all CPUs matters. A task can increase this counter on
232 * one CPU and if it got migrated afterwards it may decrease
233 * it on another CPU. Always updated under the runqueue lock:
235 unsigned long nr_uninterruptible
;
237 unsigned long expired_timestamp
;
238 /* Cached timestamp set by update_cpu_clock() */
239 unsigned long long most_recent_timestamp
;
240 struct task_struct
*curr
, *idle
;
241 unsigned long next_balance
;
242 struct mm_struct
*prev_mm
;
243 struct prio_array
*active
, *expired
, arrays
[2];
244 int best_expired_prio
;
248 struct sched_domain
*sd
;
250 /* For active balancing */
253 int cpu
; /* cpu of this runqueue */
255 struct task_struct
*migration_thread
;
256 struct list_head migration_queue
;
259 #ifdef CONFIG_SCHEDSTATS
261 struct sched_info rq_sched_info
;
263 /* sys_sched_yield() stats */
264 unsigned long yld_exp_empty
;
265 unsigned long yld_act_empty
;
266 unsigned long yld_both_empty
;
267 unsigned long yld_cnt
;
269 /* schedule() stats */
270 unsigned long sched_switch
;
271 unsigned long sched_cnt
;
272 unsigned long sched_goidle
;
274 /* try_to_wake_up() stats */
275 unsigned long ttwu_cnt
;
276 unsigned long ttwu_local
;
278 struct lock_class_key rq_lock_key
;
281 static DEFINE_PER_CPU(struct rq
, runqueues
);
283 static inline int cpu_of(struct rq
*rq
)
293 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
294 * See detach_destroy_domains: synchronize_sched for details.
296 * The domain tree of any CPU may only be accessed from within
297 * preempt-disabled sections.
299 #define for_each_domain(cpu, __sd) \
300 for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
302 #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
303 #define this_rq() (&__get_cpu_var(runqueues))
304 #define task_rq(p) cpu_rq(task_cpu(p))
305 #define cpu_curr(cpu) (cpu_rq(cpu)->curr)
307 #ifndef prepare_arch_switch
308 # define prepare_arch_switch(next) do { } while (0)
310 #ifndef finish_arch_switch
311 # define finish_arch_switch(prev) do { } while (0)
314 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
315 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
317 return rq
->curr
== p
;
320 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
324 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
326 #ifdef CONFIG_DEBUG_SPINLOCK
327 /* this is a valid case when another task releases the spinlock */
328 rq
->lock
.owner
= current
;
331 * If we are tracking spinlock dependencies then we have to
332 * fix up the runqueue lock - which gets 'carried over' from
335 spin_acquire(&rq
->lock
.dep_map
, 0, 0, _THIS_IP_
);
337 spin_unlock_irq(&rq
->lock
);
340 #else /* __ARCH_WANT_UNLOCKED_CTXSW */
341 static inline int task_running(struct rq
*rq
, struct task_struct
*p
)
346 return rq
->curr
== p
;
350 static inline void prepare_lock_switch(struct rq
*rq
, struct task_struct
*next
)
354 * We can optimise this out completely for !SMP, because the
355 * SMP rebalancing from interrupt is the only thing that cares
360 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
361 spin_unlock_irq(&rq
->lock
);
363 spin_unlock(&rq
->lock
);
367 static inline void finish_lock_switch(struct rq
*rq
, struct task_struct
*prev
)
371 * After ->oncpu is cleared, the task can be moved to a different CPU.
372 * We must ensure this doesn't happen until the switch is completely
378 #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
382 #endif /* __ARCH_WANT_UNLOCKED_CTXSW */
385 * __task_rq_lock - lock the runqueue a given task resides on.
386 * Must be called interrupts disabled.
388 static inline struct rq
*__task_rq_lock(struct task_struct
*p
)
395 spin_lock(&rq
->lock
);
396 if (unlikely(rq
!= task_rq(p
))) {
397 spin_unlock(&rq
->lock
);
398 goto repeat_lock_task
;
404 * task_rq_lock - lock the runqueue a given task resides on and disable
405 * interrupts. Note the ordering: we can safely lookup the task_rq without
406 * explicitly disabling preemption.
408 static struct rq
*task_rq_lock(struct task_struct
*p
, unsigned long *flags
)
414 local_irq_save(*flags
);
416 spin_lock(&rq
->lock
);
417 if (unlikely(rq
!= task_rq(p
))) {
418 spin_unlock_irqrestore(&rq
->lock
, *flags
);
419 goto repeat_lock_task
;
424 static inline void __task_rq_unlock(struct rq
*rq
)
427 spin_unlock(&rq
->lock
);
430 static inline void task_rq_unlock(struct rq
*rq
, unsigned long *flags
)
433 spin_unlock_irqrestore(&rq
->lock
, *flags
);
436 #ifdef CONFIG_SCHEDSTATS
438 * bump this up when changing the output format or the meaning of an existing
439 * format, so that tools can adapt (or abort)
441 #define SCHEDSTAT_VERSION 14
443 static int show_schedstat(struct seq_file
*seq
, void *v
)
447 seq_printf(seq
, "version %d\n", SCHEDSTAT_VERSION
);
448 seq_printf(seq
, "timestamp %lu\n", jiffies
);
449 for_each_online_cpu(cpu
) {
450 struct rq
*rq
= cpu_rq(cpu
);
452 struct sched_domain
*sd
;
456 /* runqueue-specific stats */
458 "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
459 cpu
, rq
->yld_both_empty
,
460 rq
->yld_act_empty
, rq
->yld_exp_empty
, rq
->yld_cnt
,
461 rq
->sched_switch
, rq
->sched_cnt
, rq
->sched_goidle
,
462 rq
->ttwu_cnt
, rq
->ttwu_local
,
463 rq
->rq_sched_info
.cpu_time
,
464 rq
->rq_sched_info
.run_delay
, rq
->rq_sched_info
.pcnt
);
466 seq_printf(seq
, "\n");
469 /* domain-specific stats */
471 for_each_domain(cpu
, sd
) {
472 enum idle_type itype
;
473 char mask_str
[NR_CPUS
];
475 cpumask_scnprintf(mask_str
, NR_CPUS
, sd
->span
);
476 seq_printf(seq
, "domain%d %s", dcnt
++, mask_str
);
477 for (itype
= SCHED_IDLE
; itype
< MAX_IDLE_TYPES
;
479 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu "
482 sd
->lb_balanced
[itype
],
483 sd
->lb_failed
[itype
],
484 sd
->lb_imbalance
[itype
],
485 sd
->lb_gained
[itype
],
486 sd
->lb_hot_gained
[itype
],
487 sd
->lb_nobusyq
[itype
],
488 sd
->lb_nobusyg
[itype
]);
490 seq_printf(seq
, " %lu %lu %lu %lu %lu %lu %lu %lu %lu"
492 sd
->alb_cnt
, sd
->alb_failed
, sd
->alb_pushed
,
493 sd
->sbe_cnt
, sd
->sbe_balanced
, sd
->sbe_pushed
,
494 sd
->sbf_cnt
, sd
->sbf_balanced
, sd
->sbf_pushed
,
495 sd
->ttwu_wake_remote
, sd
->ttwu_move_affine
,
496 sd
->ttwu_move_balance
);
504 static int schedstat_open(struct inode
*inode
, struct file
*file
)
506 unsigned int size
= PAGE_SIZE
* (1 + num_online_cpus() / 32);
507 char *buf
= kmalloc(size
, GFP_KERNEL
);
513 res
= single_open(file
, show_schedstat
, NULL
);
515 m
= file
->private_data
;
523 const struct file_operations proc_schedstat_operations
= {
524 .open
= schedstat_open
,
527 .release
= single_release
,
531 * Expects runqueue lock to be held for atomicity of update
534 rq_sched_info_arrive(struct rq
*rq
, unsigned long delta_jiffies
)
537 rq
->rq_sched_info
.run_delay
+= delta_jiffies
;
538 rq
->rq_sched_info
.pcnt
++;
543 * Expects runqueue lock to be held for atomicity of update
546 rq_sched_info_depart(struct rq
*rq
, unsigned long delta_jiffies
)
549 rq
->rq_sched_info
.cpu_time
+= delta_jiffies
;
551 # define schedstat_inc(rq, field) do { (rq)->field++; } while (0)
552 # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0)
553 #else /* !CONFIG_SCHEDSTATS */
555 rq_sched_info_arrive(struct rq
*rq
, unsigned long delta_jiffies
)
558 rq_sched_info_depart(struct rq
*rq
, unsigned long delta_jiffies
)
560 # define schedstat_inc(rq, field) do { } while (0)
561 # define schedstat_add(rq, field, amt) do { } while (0)
565 * this_rq_lock - lock this runqueue and disable interrupts.
567 static inline struct rq
*this_rq_lock(void)
574 spin_lock(&rq
->lock
);
579 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
581 * Called when a process is dequeued from the active array and given
582 * the cpu. We should note that with the exception of interactive
583 * tasks, the expired queue will become the active queue after the active
584 * queue is empty, without explicitly dequeuing and requeuing tasks in the
585 * expired queue. (Interactive tasks may be requeued directly to the
586 * active queue, thus delaying tasks in the expired queue from running;
587 * see scheduler_tick()).
589 * This function is only called from sched_info_arrive(), rather than
590 * dequeue_task(). Even though a task may be queued and dequeued multiple
591 * times as it is shuffled about, we're really interested in knowing how
592 * long it was from the *first* time it was queued to the time that it
595 static inline void sched_info_dequeued(struct task_struct
*t
)
597 t
->sched_info
.last_queued
= 0;
601 * Called when a task finally hits the cpu. We can now calculate how
602 * long it was waiting to run. We also note when it began so that we
603 * can keep stats on how long its timeslice is.
605 static void sched_info_arrive(struct task_struct
*t
)
607 unsigned long now
= jiffies
, delta_jiffies
= 0;
609 if (t
->sched_info
.last_queued
)
610 delta_jiffies
= now
- t
->sched_info
.last_queued
;
611 sched_info_dequeued(t
);
612 t
->sched_info
.run_delay
+= delta_jiffies
;
613 t
->sched_info
.last_arrival
= now
;
614 t
->sched_info
.pcnt
++;
616 rq_sched_info_arrive(task_rq(t
), delta_jiffies
);
620 * Called when a process is queued into either the active or expired
621 * array. The time is noted and later used to determine how long we
622 * had to wait for us to reach the cpu. Since the expired queue will
623 * become the active queue after active queue is empty, without dequeuing
624 * and requeuing any tasks, we are interested in queuing to either. It
625 * is unusual but not impossible for tasks to be dequeued and immediately
626 * requeued in the same or another array: this can happen in sched_yield(),
627 * set_user_nice(), and even load_balance() as it moves tasks from runqueue
630 * This function is only called from enqueue_task(), but also only updates
631 * the timestamp if it is already not set. It's assumed that
632 * sched_info_dequeued() will clear that stamp when appropriate.
634 static inline void sched_info_queued(struct task_struct
*t
)
636 if (unlikely(sched_info_on()))
637 if (!t
->sched_info
.last_queued
)
638 t
->sched_info
.last_queued
= jiffies
;
642 * Called when a process ceases being the active-running process, either
643 * voluntarily or involuntarily. Now we can calculate how long we ran.
645 static inline void sched_info_depart(struct task_struct
*t
)
647 unsigned long delta_jiffies
= jiffies
- t
->sched_info
.last_arrival
;
649 t
->sched_info
.cpu_time
+= delta_jiffies
;
650 rq_sched_info_depart(task_rq(t
), delta_jiffies
);
654 * Called when tasks are switched involuntarily due, typically, to expiring
655 * their time slice. (This may also be called when switching to or from
656 * the idle task.) We are only called when prev != next.
659 __sched_info_switch(struct task_struct
*prev
, struct task_struct
*next
)
661 struct rq
*rq
= task_rq(prev
);
664 * prev now departs the cpu. It's not interesting to record
665 * stats about how efficient we were at scheduling the idle
668 if (prev
!= rq
->idle
)
669 sched_info_depart(prev
);
671 if (next
!= rq
->idle
)
672 sched_info_arrive(next
);
675 sched_info_switch(struct task_struct
*prev
, struct task_struct
*next
)
677 if (unlikely(sched_info_on()))
678 __sched_info_switch(prev
, next
);
681 #define sched_info_queued(t) do { } while (0)
682 #define sched_info_switch(t, next) do { } while (0)
683 #endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */
686 * Adding/removing a task to/from a priority array:
688 static void dequeue_task(struct task_struct
*p
, struct prio_array
*array
)
691 list_del(&p
->run_list
);
692 if (list_empty(array
->queue
+ p
->prio
))
693 __clear_bit(p
->prio
, array
->bitmap
);
696 static void enqueue_task(struct task_struct
*p
, struct prio_array
*array
)
698 sched_info_queued(p
);
699 list_add_tail(&p
->run_list
, array
->queue
+ p
->prio
);
700 __set_bit(p
->prio
, array
->bitmap
);
706 * Put task to the end of the run list without the overhead of dequeue
707 * followed by enqueue.
709 static void requeue_task(struct task_struct
*p
, struct prio_array
*array
)
711 list_move_tail(&p
->run_list
, array
->queue
+ p
->prio
);
715 enqueue_task_head(struct task_struct
*p
, struct prio_array
*array
)
717 list_add(&p
->run_list
, array
->queue
+ p
->prio
);
718 __set_bit(p
->prio
, array
->bitmap
);
724 * __normal_prio - return the priority that is based on the static
725 * priority but is modified by bonuses/penalties.
727 * We scale the actual sleep average [0 .... MAX_SLEEP_AVG]
728 * into the -5 ... 0 ... +5 bonus/penalty range.
730 * We use 25% of the full 0...39 priority range so that:
732 * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs.
733 * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks.
735 * Both properties are important to certain workloads.
738 static inline int __normal_prio(struct task_struct
*p
)
742 bonus
= CURRENT_BONUS(p
) - MAX_BONUS
/ 2;
744 prio
= p
->static_prio
- bonus
;
745 if (prio
< MAX_RT_PRIO
)
747 if (prio
> MAX_PRIO
-1)
753 * To aid in avoiding the subversion of "niceness" due to uneven distribution
754 * of tasks with abnormal "nice" values across CPUs the contribution that
755 * each task makes to its run queue's load is weighted according to its
756 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
757 * scaled version of the new time slice allocation that they receive on time
762 * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE
763 * If static_prio_timeslice() is ever changed to break this assumption then
764 * this code will need modification
766 #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
767 #define LOAD_WEIGHT(lp) \
768 (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
769 #define PRIO_TO_LOAD_WEIGHT(prio) \
770 LOAD_WEIGHT(static_prio_timeslice(prio))
771 #define RTPRIO_TO_LOAD_WEIGHT(rp) \
772 (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
774 static void set_load_weight(struct task_struct
*p
)
776 if (has_rt_policy(p
)) {
778 if (p
== task_rq(p
)->migration_thread
)
780 * The migration thread does the actual balancing.
781 * Giving its load any weight will skew balancing
787 p
->load_weight
= RTPRIO_TO_LOAD_WEIGHT(p
->rt_priority
);
789 p
->load_weight
= PRIO_TO_LOAD_WEIGHT(p
->static_prio
);
793 inc_raw_weighted_load(struct rq
*rq
, const struct task_struct
*p
)
795 rq
->raw_weighted_load
+= p
->load_weight
;
799 dec_raw_weighted_load(struct rq
*rq
, const struct task_struct
*p
)
801 rq
->raw_weighted_load
-= p
->load_weight
;
804 static inline void inc_nr_running(struct task_struct
*p
, struct rq
*rq
)
807 inc_raw_weighted_load(rq
, p
);
810 static inline void dec_nr_running(struct task_struct
*p
, struct rq
*rq
)
813 dec_raw_weighted_load(rq
, p
);
817 * Calculate the expected normal priority: i.e. priority
818 * without taking RT-inheritance into account. Might be
819 * boosted by interactivity modifiers. Changes upon fork,
820 * setprio syscalls, and whenever the interactivity
821 * estimator recalculates.
823 static inline int normal_prio(struct task_struct
*p
)
827 if (has_rt_policy(p
))
828 prio
= MAX_RT_PRIO
-1 - p
->rt_priority
;
830 prio
= __normal_prio(p
);
835 * Calculate the current priority, i.e. the priority
836 * taken into account by the scheduler. This value might
837 * be boosted by RT tasks, or might be boosted by
838 * interactivity modifiers. Will be RT if the task got
839 * RT-boosted. If not then it returns p->normal_prio.
841 static int effective_prio(struct task_struct
*p
)
843 p
->normal_prio
= normal_prio(p
);
845 * If we are RT tasks or we were boosted to RT priority,
846 * keep the priority unchanged. Otherwise, update priority
847 * to the normal priority:
849 if (!rt_prio(p
->prio
))
850 return p
->normal_prio
;
855 * __activate_task - move a task to the runqueue.
857 static void __activate_task(struct task_struct
*p
, struct rq
*rq
)
859 struct prio_array
*target
= rq
->active
;
862 target
= rq
->expired
;
863 enqueue_task(p
, target
);
864 inc_nr_running(p
, rq
);
868 * __activate_idle_task - move idle task to the _front_ of runqueue.
870 static inline void __activate_idle_task(struct task_struct
*p
, struct rq
*rq
)
872 enqueue_task_head(p
, rq
->active
);
873 inc_nr_running(p
, rq
);
877 * Recalculate p->normal_prio and p->prio after having slept,
878 * updating the sleep-average too:
880 static int recalc_task_prio(struct task_struct
*p
, unsigned long long now
)
882 /* Caller must always ensure 'now >= p->timestamp' */
883 unsigned long sleep_time
= now
- p
->timestamp
;
888 if (likely(sleep_time
> 0)) {
890 * This ceiling is set to the lowest priority that would allow
891 * a task to be reinserted into the active array on timeslice
894 unsigned long ceiling
= INTERACTIVE_SLEEP(p
);
896 if (p
->mm
&& sleep_time
> ceiling
&& p
->sleep_avg
< ceiling
) {
898 * Prevents user tasks from achieving best priority
899 * with one single large enough sleep.
901 p
->sleep_avg
= ceiling
;
903 * Using INTERACTIVE_SLEEP() as a ceiling places a
904 * nice(0) task 1ms sleep away from promotion, and
905 * gives it 700ms to round-robin with no chance of
906 * being demoted. This is more than generous, so
907 * mark this sleep as non-interactive to prevent the
908 * on-runqueue bonus logic from intervening should
909 * this task not receive cpu immediately.
911 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
914 * Tasks waking from uninterruptible sleep are
915 * limited in their sleep_avg rise as they
916 * are likely to be waiting on I/O
918 if (p
->sleep_type
== SLEEP_NONINTERACTIVE
&& p
->mm
) {
919 if (p
->sleep_avg
>= ceiling
)
921 else if (p
->sleep_avg
+ sleep_time
>=
923 p
->sleep_avg
= ceiling
;
929 * This code gives a bonus to interactive tasks.
931 * The boost works by updating the 'average sleep time'
932 * value here, based on ->timestamp. The more time a
933 * task spends sleeping, the higher the average gets -
934 * and the higher the priority boost gets as well.
936 p
->sleep_avg
+= sleep_time
;
939 if (p
->sleep_avg
> NS_MAX_SLEEP_AVG
)
940 p
->sleep_avg
= NS_MAX_SLEEP_AVG
;
943 return effective_prio(p
);
947 * activate_task - move a task to the runqueue and do priority recalculation
949 * Update all the scheduling statistics stuff. (sleep average
950 * calculation, priority modifiers, etc.)
952 static void activate_task(struct task_struct
*p
, struct rq
*rq
, int local
)
954 unsigned long long now
;
962 /* Compensate for drifting sched_clock */
963 struct rq
*this_rq
= this_rq();
964 now
= (now
- this_rq
->most_recent_timestamp
)
965 + rq
->most_recent_timestamp
;
970 * Sleep time is in units of nanosecs, so shift by 20 to get a
971 * milliseconds-range estimation of the amount of time that the task
974 if (unlikely(prof_on
== SLEEP_PROFILING
)) {
975 if (p
->state
== TASK_UNINTERRUPTIBLE
)
976 profile_hits(SLEEP_PROFILING
, (void *)get_wchan(p
),
977 (now
- p
->timestamp
) >> 20);
980 p
->prio
= recalc_task_prio(p
, now
);
983 * This checks to make sure it's not an uninterruptible task
984 * that is now waking up.
986 if (p
->sleep_type
== SLEEP_NORMAL
) {
988 * Tasks which were woken up by interrupts (ie. hw events)
989 * are most likely of interactive nature. So we give them
990 * the credit of extending their sleep time to the period
991 * of time they spend on the runqueue, waiting for execution
992 * on a CPU, first time around:
995 p
->sleep_type
= SLEEP_INTERRUPTED
;
998 * Normal first-time wakeups get a credit too for
999 * on-runqueue time, but it will be weighted down:
1001 p
->sleep_type
= SLEEP_INTERACTIVE
;
1006 __activate_task(p
, rq
);
1010 * deactivate_task - remove a task from the runqueue.
1012 static void deactivate_task(struct task_struct
*p
, struct rq
*rq
)
1014 dec_nr_running(p
, rq
);
1015 dequeue_task(p
, p
->array
);
1020 * resched_task - mark a task 'to be rescheduled now'.
1022 * On UP this means the setting of the need_resched flag, on SMP it
1023 * might also involve a cross-CPU call to trigger the scheduler on
1028 #ifndef tsk_is_polling
1029 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1032 static void resched_task(struct task_struct
*p
)
1036 assert_spin_locked(&task_rq(p
)->lock
);
1038 if (unlikely(test_tsk_thread_flag(p
, TIF_NEED_RESCHED
)))
1041 set_tsk_thread_flag(p
, TIF_NEED_RESCHED
);
1044 if (cpu
== smp_processor_id())
1047 /* NEED_RESCHED must be visible before we test polling */
1049 if (!tsk_is_polling(p
))
1050 smp_send_reschedule(cpu
);
1053 static inline void resched_task(struct task_struct
*p
)
1055 assert_spin_locked(&task_rq(p
)->lock
);
1056 set_tsk_need_resched(p
);
1061 * task_curr - is this task currently executing on a CPU?
1062 * @p: the task in question.
1064 inline int task_curr(const struct task_struct
*p
)
1066 return cpu_curr(task_cpu(p
)) == p
;
1069 /* Used instead of source_load when we know the type == 0 */
1070 unsigned long weighted_cpuload(const int cpu
)
1072 return cpu_rq(cpu
)->raw_weighted_load
;
1076 struct migration_req
{
1077 struct list_head list
;
1079 struct task_struct
*task
;
1082 struct completion done
;
1086 * The task's runqueue lock must be held.
1087 * Returns true if you have to wait for migration thread.
1090 migrate_task(struct task_struct
*p
, int dest_cpu
, struct migration_req
*req
)
1092 struct rq
*rq
= task_rq(p
);
1095 * If the task is not on a runqueue (and not running), then
1096 * it is sufficient to simply update the task's cpu field.
1098 if (!p
->array
&& !task_running(rq
, p
)) {
1099 set_task_cpu(p
, dest_cpu
);
1103 init_completion(&req
->done
);
1105 req
->dest_cpu
= dest_cpu
;
1106 list_add(&req
->list
, &rq
->migration_queue
);
1112 * wait_task_inactive - wait for a thread to unschedule.
1114 * The caller must ensure that the task *will* unschedule sometime soon,
1115 * else this function might spin for a *long* time. This function can't
1116 * be called with interrupts off, or it may introduce deadlock with
1117 * smp_call_function() if an IPI is sent by the same process we are
1118 * waiting to become inactive.
1120 void wait_task_inactive(struct task_struct
*p
)
1122 unsigned long flags
;
1127 rq
= task_rq_lock(p
, &flags
);
1128 /* Must be off runqueue entirely, not preempted. */
1129 if (unlikely(p
->array
|| task_running(rq
, p
))) {
1130 /* If it's preempted, we yield. It could be a while. */
1131 preempted
= !task_running(rq
, p
);
1132 task_rq_unlock(rq
, &flags
);
1138 task_rq_unlock(rq
, &flags
);
1142 * kick_process - kick a running thread to enter/exit the kernel
1143 * @p: the to-be-kicked thread
1145 * Cause a process which is running on another CPU to enter
1146 * kernel-mode, without any delay. (to get signals handled.)
1148 * NOTE: this function doesnt have to take the runqueue lock,
1149 * because all it wants to ensure is that the remote task enters
1150 * the kernel. If the IPI races and the task has been migrated
1151 * to another CPU then no harm is done and the purpose has been
1154 void kick_process(struct task_struct
*p
)
1160 if ((cpu
!= smp_processor_id()) && task_curr(p
))
1161 smp_send_reschedule(cpu
);
1166 * Return a low guess at the load of a migration-source cpu weighted
1167 * according to the scheduling class and "nice" value.
1169 * We want to under-estimate the load of migration sources, to
1170 * balance conservatively.
1172 static inline unsigned long source_load(int cpu
, int type
)
1174 struct rq
*rq
= cpu_rq(cpu
);
1177 return rq
->raw_weighted_load
;
1179 return min(rq
->cpu_load
[type
-1], rq
->raw_weighted_load
);
1183 * Return a high guess at the load of a migration-target cpu weighted
1184 * according to the scheduling class and "nice" value.
1186 static inline unsigned long target_load(int cpu
, int type
)
1188 struct rq
*rq
= cpu_rq(cpu
);
1191 return rq
->raw_weighted_load
;
1193 return max(rq
->cpu_load
[type
-1], rq
->raw_weighted_load
);
1197 * Return the average load per task on the cpu's run queue
1199 static inline unsigned long cpu_avg_load_per_task(int cpu
)
1201 struct rq
*rq
= cpu_rq(cpu
);
1202 unsigned long n
= rq
->nr_running
;
1204 return n
? rq
->raw_weighted_load
/ n
: SCHED_LOAD_SCALE
;
1208 * find_idlest_group finds and returns the least busy CPU group within the
1211 static struct sched_group
*
1212 find_idlest_group(struct sched_domain
*sd
, struct task_struct
*p
, int this_cpu
)
1214 struct sched_group
*idlest
= NULL
, *this = NULL
, *group
= sd
->groups
;
1215 unsigned long min_load
= ULONG_MAX
, this_load
= 0;
1216 int load_idx
= sd
->forkexec_idx
;
1217 int imbalance
= 100 + (sd
->imbalance_pct
-100)/2;
1220 unsigned long load
, avg_load
;
1224 /* Skip over this group if it has no CPUs allowed */
1225 if (!cpus_intersects(group
->cpumask
, p
->cpus_allowed
))
1228 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
1230 /* Tally up the load of all CPUs in the group */
1233 for_each_cpu_mask(i
, group
->cpumask
) {
1234 /* Bias balancing toward cpus of our domain */
1236 load
= source_load(i
, load_idx
);
1238 load
= target_load(i
, load_idx
);
1243 /* Adjust by relative CPU power of the group */
1244 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
1247 this_load
= avg_load
;
1249 } else if (avg_load
< min_load
) {
1250 min_load
= avg_load
;
1254 group
= group
->next
;
1255 } while (group
!= sd
->groups
);
1257 if (!idlest
|| 100*this_load
< imbalance
*min_load
)
1263 * find_idlest_cpu - find the idlest cpu among the cpus in group.
1266 find_idlest_cpu(struct sched_group
*group
, struct task_struct
*p
, int this_cpu
)
1269 unsigned long load
, min_load
= ULONG_MAX
;
1273 /* Traverse only the allowed CPUs */
1274 cpus_and(tmp
, group
->cpumask
, p
->cpus_allowed
);
1276 for_each_cpu_mask(i
, tmp
) {
1277 load
= weighted_cpuload(i
);
1279 if (load
< min_load
|| (load
== min_load
&& i
== this_cpu
)) {
1289 * sched_balance_self: balance the current task (running on cpu) in domains
1290 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
1293 * Balance, ie. select the least loaded group.
1295 * Returns the target CPU number, or the same CPU if no balancing is needed.
1297 * preempt must be disabled.
1299 static int sched_balance_self(int cpu
, int flag
)
1301 struct task_struct
*t
= current
;
1302 struct sched_domain
*tmp
, *sd
= NULL
;
1304 for_each_domain(cpu
, tmp
) {
1306 * If power savings logic is enabled for a domain, stop there.
1308 if (tmp
->flags
& SD_POWERSAVINGS_BALANCE
)
1310 if (tmp
->flags
& flag
)
1316 struct sched_group
*group
;
1317 int new_cpu
, weight
;
1319 if (!(sd
->flags
& flag
)) {
1325 group
= find_idlest_group(sd
, t
, cpu
);
1331 new_cpu
= find_idlest_cpu(group
, t
, cpu
);
1332 if (new_cpu
== -1 || new_cpu
== cpu
) {
1333 /* Now try balancing at a lower domain level of cpu */
1338 /* Now try balancing at a lower domain level of new_cpu */
1341 weight
= cpus_weight(span
);
1342 for_each_domain(cpu
, tmp
) {
1343 if (weight
<= cpus_weight(tmp
->span
))
1345 if (tmp
->flags
& flag
)
1348 /* while loop will break here if sd == NULL */
1354 #endif /* CONFIG_SMP */
1357 * wake_idle() will wake a task on an idle cpu if task->cpu is
1358 * not idle and an idle cpu is available. The span of cpus to
1359 * search starts with cpus closest then further out as needed,
1360 * so we always favor a closer, idle cpu.
1362 * Returns the CPU we should wake onto.
1364 #if defined(ARCH_HAS_SCHED_WAKE_IDLE)
1365 static int wake_idle(int cpu
, struct task_struct
*p
)
1368 struct sched_domain
*sd
;
1374 for_each_domain(cpu
, sd
) {
1375 if (sd
->flags
& SD_WAKE_IDLE
) {
1376 cpus_and(tmp
, sd
->span
, p
->cpus_allowed
);
1377 for_each_cpu_mask(i
, tmp
) {
1388 static inline int wake_idle(int cpu
, struct task_struct
*p
)
1395 * try_to_wake_up - wake up a thread
1396 * @p: the to-be-woken-up thread
1397 * @state: the mask of task states that can be woken
1398 * @sync: do a synchronous wakeup?
1400 * Put it on the run-queue if it's not already there. The "current"
1401 * thread is always on the run-queue (except when the actual
1402 * re-schedule is in progress), and as such you're allowed to do
1403 * the simpler "current->state = TASK_RUNNING" to mark yourself
1404 * runnable without the overhead of this.
1406 * returns failure only if the task is already active.
1408 static int try_to_wake_up(struct task_struct
*p
, unsigned int state
, int sync
)
1410 int cpu
, this_cpu
, success
= 0;
1411 unsigned long flags
;
1415 struct sched_domain
*sd
, *this_sd
= NULL
;
1416 unsigned long load
, this_load
;
1420 rq
= task_rq_lock(p
, &flags
);
1421 old_state
= p
->state
;
1422 if (!(old_state
& state
))
1429 this_cpu
= smp_processor_id();
1432 if (unlikely(task_running(rq
, p
)))
1437 schedstat_inc(rq
, ttwu_cnt
);
1438 if (cpu
== this_cpu
) {
1439 schedstat_inc(rq
, ttwu_local
);
1443 for_each_domain(this_cpu
, sd
) {
1444 if (cpu_isset(cpu
, sd
->span
)) {
1445 schedstat_inc(sd
, ttwu_wake_remote
);
1451 if (unlikely(!cpu_isset(this_cpu
, p
->cpus_allowed
)))
1455 * Check for affine wakeup and passive balancing possibilities.
1458 int idx
= this_sd
->wake_idx
;
1459 unsigned int imbalance
;
1461 imbalance
= 100 + (this_sd
->imbalance_pct
- 100) / 2;
1463 load
= source_load(cpu
, idx
);
1464 this_load
= target_load(this_cpu
, idx
);
1466 new_cpu
= this_cpu
; /* Wake to this CPU if we can */
1468 if (this_sd
->flags
& SD_WAKE_AFFINE
) {
1469 unsigned long tl
= this_load
;
1470 unsigned long tl_per_task
;
1472 tl_per_task
= cpu_avg_load_per_task(this_cpu
);
1475 * If sync wakeup then subtract the (maximum possible)
1476 * effect of the currently running task from the load
1477 * of the current CPU:
1480 tl
-= current
->load_weight
;
1483 tl
+ target_load(cpu
, idx
) <= tl_per_task
) ||
1484 100*(tl
+ p
->load_weight
) <= imbalance
*load
) {
1486 * This domain has SD_WAKE_AFFINE and
1487 * p is cache cold in this domain, and
1488 * there is no bad imbalance.
1490 schedstat_inc(this_sd
, ttwu_move_affine
);
1496 * Start passive balancing when half the imbalance_pct
1499 if (this_sd
->flags
& SD_WAKE_BALANCE
) {
1500 if (imbalance
*this_load
<= 100*load
) {
1501 schedstat_inc(this_sd
, ttwu_move_balance
);
1507 new_cpu
= cpu
; /* Could not wake to this_cpu. Wake to cpu instead */
1509 new_cpu
= wake_idle(new_cpu
, p
);
1510 if (new_cpu
!= cpu
) {
1511 set_task_cpu(p
, new_cpu
);
1512 task_rq_unlock(rq
, &flags
);
1513 /* might preempt at this point */
1514 rq
= task_rq_lock(p
, &flags
);
1515 old_state
= p
->state
;
1516 if (!(old_state
& state
))
1521 this_cpu
= smp_processor_id();
1526 #endif /* CONFIG_SMP */
1527 if (old_state
== TASK_UNINTERRUPTIBLE
) {
1528 rq
->nr_uninterruptible
--;
1530 * Tasks on involuntary sleep don't earn
1531 * sleep_avg beyond just interactive state.
1533 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1537 * Tasks that have marked their sleep as noninteractive get
1538 * woken up with their sleep average not weighted in an
1541 if (old_state
& TASK_NONINTERACTIVE
)
1542 p
->sleep_type
= SLEEP_NONINTERACTIVE
;
1545 activate_task(p
, rq
, cpu
== this_cpu
);
1547 * Sync wakeups (i.e. those types of wakeups where the waker
1548 * has indicated that it will leave the CPU in short order)
1549 * don't trigger a preemption, if the woken up task will run on
1550 * this cpu. (in this case the 'I will reschedule' promise of
1551 * the waker guarantees that the freshly woken up task is going
1552 * to be considered on this CPU.)
1554 if (!sync
|| cpu
!= this_cpu
) {
1555 if (TASK_PREEMPTS_CURR(p
, rq
))
1556 resched_task(rq
->curr
);
1561 p
->state
= TASK_RUNNING
;
1563 task_rq_unlock(rq
, &flags
);
1568 int fastcall
wake_up_process(struct task_struct
*p
)
1570 return try_to_wake_up(p
, TASK_STOPPED
| TASK_TRACED
|
1571 TASK_INTERRUPTIBLE
| TASK_UNINTERRUPTIBLE
, 0);
1573 EXPORT_SYMBOL(wake_up_process
);
1575 int fastcall
wake_up_state(struct task_struct
*p
, unsigned int state
)
1577 return try_to_wake_up(p
, state
, 0);
1580 static void task_running_tick(struct rq
*rq
, struct task_struct
*p
);
1582 * Perform scheduler related setup for a newly forked process p.
1583 * p is forked by current.
1585 void fastcall
sched_fork(struct task_struct
*p
, int clone_flags
)
1587 int cpu
= get_cpu();
1590 cpu
= sched_balance_self(cpu
, SD_BALANCE_FORK
);
1592 set_task_cpu(p
, cpu
);
1595 * We mark the process as running here, but have not actually
1596 * inserted it onto the runqueue yet. This guarantees that
1597 * nobody will actually run it, and a signal or other external
1598 * event cannot wake it up and insert it on the runqueue either.
1600 p
->state
= TASK_RUNNING
;
1603 * Make sure we do not leak PI boosting priority to the child:
1605 p
->prio
= current
->normal_prio
;
1607 INIT_LIST_HEAD(&p
->run_list
);
1609 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1610 if (unlikely(sched_info_on()))
1611 memset(&p
->sched_info
, 0, sizeof(p
->sched_info
));
1613 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
1616 #ifdef CONFIG_PREEMPT
1617 /* Want to start with kernel preemption disabled. */
1618 task_thread_info(p
)->preempt_count
= 1;
1621 * Share the timeslice between parent and child, thus the
1622 * total amount of pending timeslices in the system doesn't change,
1623 * resulting in more scheduling fairness.
1625 local_irq_disable();
1626 p
->time_slice
= (current
->time_slice
+ 1) >> 1;
1628 * The remainder of the first timeslice might be recovered by
1629 * the parent if the child exits early enough.
1631 p
->first_time_slice
= 1;
1632 current
->time_slice
>>= 1;
1633 p
->timestamp
= sched_clock();
1634 if (unlikely(!current
->time_slice
)) {
1636 * This case is rare, it happens when the parent has only
1637 * a single jiffy left from its timeslice. Taking the
1638 * runqueue lock is not a problem.
1640 current
->time_slice
= 1;
1641 task_running_tick(cpu_rq(cpu
), current
);
1648 * wake_up_new_task - wake up a newly created task for the first time.
1650 * This function will do some initial scheduler statistics housekeeping
1651 * that must be done for every newly created context, then puts the task
1652 * on the runqueue and wakes it.
1654 void fastcall
wake_up_new_task(struct task_struct
*p
, unsigned long clone_flags
)
1656 struct rq
*rq
, *this_rq
;
1657 unsigned long flags
;
1660 rq
= task_rq_lock(p
, &flags
);
1661 BUG_ON(p
->state
!= TASK_RUNNING
);
1662 this_cpu
= smp_processor_id();
1666 * We decrease the sleep average of forking parents
1667 * and children as well, to keep max-interactive tasks
1668 * from forking tasks that are max-interactive. The parent
1669 * (current) is done further down, under its lock.
1671 p
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(p
) *
1672 CHILD_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1674 p
->prio
= effective_prio(p
);
1676 if (likely(cpu
== this_cpu
)) {
1677 if (!(clone_flags
& CLONE_VM
)) {
1679 * The VM isn't cloned, so we're in a good position to
1680 * do child-runs-first in anticipation of an exec. This
1681 * usually avoids a lot of COW overhead.
1683 if (unlikely(!current
->array
))
1684 __activate_task(p
, rq
);
1686 p
->prio
= current
->prio
;
1687 p
->normal_prio
= current
->normal_prio
;
1688 list_add_tail(&p
->run_list
, ¤t
->run_list
);
1689 p
->array
= current
->array
;
1690 p
->array
->nr_active
++;
1691 inc_nr_running(p
, rq
);
1695 /* Run child last */
1696 __activate_task(p
, rq
);
1698 * We skip the following code due to cpu == this_cpu
1700 * task_rq_unlock(rq, &flags);
1701 * this_rq = task_rq_lock(current, &flags);
1705 this_rq
= cpu_rq(this_cpu
);
1708 * Not the local CPU - must adjust timestamp. This should
1709 * get optimised away in the !CONFIG_SMP case.
1711 p
->timestamp
= (p
->timestamp
- this_rq
->most_recent_timestamp
)
1712 + rq
->most_recent_timestamp
;
1713 __activate_task(p
, rq
);
1714 if (TASK_PREEMPTS_CURR(p
, rq
))
1715 resched_task(rq
->curr
);
1718 * Parent and child are on different CPUs, now get the
1719 * parent runqueue to update the parent's ->sleep_avg:
1721 task_rq_unlock(rq
, &flags
);
1722 this_rq
= task_rq_lock(current
, &flags
);
1724 current
->sleep_avg
= JIFFIES_TO_NS(CURRENT_BONUS(current
) *
1725 PARENT_PENALTY
/ 100 * MAX_SLEEP_AVG
/ MAX_BONUS
);
1726 task_rq_unlock(this_rq
, &flags
);
1730 * Potentially available exiting-child timeslices are
1731 * retrieved here - this way the parent does not get
1732 * penalized for creating too many threads.
1734 * (this cannot be used to 'generate' timeslices
1735 * artificially, because any timeslice recovered here
1736 * was given away by the parent in the first place.)
1738 void fastcall
sched_exit(struct task_struct
*p
)
1740 unsigned long flags
;
1744 * If the child was a (relative-) CPU hog then decrease
1745 * the sleep_avg of the parent as well.
1747 rq
= task_rq_lock(p
->parent
, &flags
);
1748 if (p
->first_time_slice
&& task_cpu(p
) == task_cpu(p
->parent
)) {
1749 p
->parent
->time_slice
+= p
->time_slice
;
1750 if (unlikely(p
->parent
->time_slice
> task_timeslice(p
)))
1751 p
->parent
->time_slice
= task_timeslice(p
);
1753 if (p
->sleep_avg
< p
->parent
->sleep_avg
)
1754 p
->parent
->sleep_avg
= p
->parent
->sleep_avg
/
1755 (EXIT_WEIGHT
+ 1) * EXIT_WEIGHT
+ p
->sleep_avg
/
1757 task_rq_unlock(rq
, &flags
);
1761 * prepare_task_switch - prepare to switch tasks
1762 * @rq: the runqueue preparing to switch
1763 * @next: the task we are going to switch to.
1765 * This is called with the rq lock held and interrupts off. It must
1766 * be paired with a subsequent finish_task_switch after the context
1769 * prepare_task_switch sets up locking and calls architecture specific
1772 static inline void prepare_task_switch(struct rq
*rq
, struct task_struct
*next
)
1774 prepare_lock_switch(rq
, next
);
1775 prepare_arch_switch(next
);
1779 * finish_task_switch - clean up after a task-switch
1780 * @rq: runqueue associated with task-switch
1781 * @prev: the thread we just switched away from.
1783 * finish_task_switch must be called after the context switch, paired
1784 * with a prepare_task_switch call before the context switch.
1785 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1786 * and do any other architecture-specific cleanup actions.
1788 * Note that we may have delayed dropping an mm in context_switch(). If
1789 * so, we finish that here outside of the runqueue lock. (Doing it
1790 * with the lock held can cause deadlocks; see schedule() for
1793 static inline void finish_task_switch(struct rq
*rq
, struct task_struct
*prev
)
1794 __releases(rq
->lock
)
1796 struct mm_struct
*mm
= rq
->prev_mm
;
1802 * A task struct has one reference for the use as "current".
1803 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1804 * schedule one last time. The schedule call will never return, and
1805 * the scheduled task must drop that reference.
1806 * The test for TASK_DEAD must occur while the runqueue locks are
1807 * still held, otherwise prev could be scheduled on another cpu, die
1808 * there before we look at prev->state, and then the reference would
1810 * Manfred Spraul <manfred@colorfullife.com>
1812 prev_state
= prev
->state
;
1813 finish_arch_switch(prev
);
1814 finish_lock_switch(rq
, prev
);
1817 if (unlikely(prev_state
== TASK_DEAD
)) {
1819 * Remove function-return probe instances associated with this
1820 * task and put them back on the free list.
1822 kprobe_flush_task(prev
);
1823 put_task_struct(prev
);
1828 * schedule_tail - first thing a freshly forked thread must call.
1829 * @prev: the thread we just switched away from.
1831 asmlinkage
void schedule_tail(struct task_struct
*prev
)
1832 __releases(rq
->lock
)
1834 struct rq
*rq
= this_rq();
1836 finish_task_switch(rq
, prev
);
1837 #ifdef __ARCH_WANT_UNLOCKED_CTXSW
1838 /* In this case, finish_task_switch does not reenable preemption */
1841 if (current
->set_child_tid
)
1842 put_user(current
->pid
, current
->set_child_tid
);
1846 * context_switch - switch to the new MM and the new
1847 * thread's register state.
1849 static inline struct task_struct
*
1850 context_switch(struct rq
*rq
, struct task_struct
*prev
,
1851 struct task_struct
*next
)
1853 struct mm_struct
*mm
= next
->mm
;
1854 struct mm_struct
*oldmm
= prev
->active_mm
;
1857 * For paravirt, this is coupled with an exit in switch_to to
1858 * combine the page table reload and the switch backend into
1861 arch_enter_lazy_cpu_mode();
1864 next
->active_mm
= oldmm
;
1865 atomic_inc(&oldmm
->mm_count
);
1866 enter_lazy_tlb(oldmm
, next
);
1868 switch_mm(oldmm
, mm
, next
);
1871 prev
->active_mm
= NULL
;
1872 WARN_ON(rq
->prev_mm
);
1873 rq
->prev_mm
= oldmm
;
1876 * Since the runqueue lock will be released by the next
1877 * task (which is an invalid locking op but in the case
1878 * of the scheduler it's an obvious special-case), so we
1879 * do an early lockdep release here:
1881 #ifndef __ARCH_WANT_UNLOCKED_CTXSW
1882 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
1885 /* Here we just switch the register state and the stack. */
1886 switch_to(prev
, next
, prev
);
1892 * nr_running, nr_uninterruptible and nr_context_switches:
1894 * externally visible scheduler statistics: current number of runnable
1895 * threads, current number of uninterruptible-sleeping threads, total
1896 * number of context switches performed since bootup.
1898 unsigned long nr_running(void)
1900 unsigned long i
, sum
= 0;
1902 for_each_online_cpu(i
)
1903 sum
+= cpu_rq(i
)->nr_running
;
1908 unsigned long nr_uninterruptible(void)
1910 unsigned long i
, sum
= 0;
1912 for_each_possible_cpu(i
)
1913 sum
+= cpu_rq(i
)->nr_uninterruptible
;
1916 * Since we read the counters lockless, it might be slightly
1917 * inaccurate. Do not allow it to go below zero though:
1919 if (unlikely((long)sum
< 0))
1925 unsigned long long nr_context_switches(void)
1928 unsigned long long sum
= 0;
1930 for_each_possible_cpu(i
)
1931 sum
+= cpu_rq(i
)->nr_switches
;
1936 unsigned long nr_iowait(void)
1938 unsigned long i
, sum
= 0;
1940 for_each_possible_cpu(i
)
1941 sum
+= atomic_read(&cpu_rq(i
)->nr_iowait
);
1946 unsigned long nr_active(void)
1948 unsigned long i
, running
= 0, uninterruptible
= 0;
1950 for_each_online_cpu(i
) {
1951 running
+= cpu_rq(i
)->nr_running
;
1952 uninterruptible
+= cpu_rq(i
)->nr_uninterruptible
;
1955 if (unlikely((long)uninterruptible
< 0))
1956 uninterruptible
= 0;
1958 return running
+ uninterruptible
;
1964 * Is this task likely cache-hot:
1967 task_hot(struct task_struct
*p
, unsigned long long now
, struct sched_domain
*sd
)
1969 return (long long)(now
- p
->last_ran
) < (long long)sd
->cache_hot_time
;
1973 * double_rq_lock - safely lock two runqueues
1975 * Note this does not disable interrupts like task_rq_lock,
1976 * you need to do so manually before calling.
1978 static void double_rq_lock(struct rq
*rq1
, struct rq
*rq2
)
1979 __acquires(rq1
->lock
)
1980 __acquires(rq2
->lock
)
1982 BUG_ON(!irqs_disabled());
1984 spin_lock(&rq1
->lock
);
1985 __acquire(rq2
->lock
); /* Fake it out ;) */
1988 spin_lock(&rq1
->lock
);
1989 spin_lock(&rq2
->lock
);
1991 spin_lock(&rq2
->lock
);
1992 spin_lock(&rq1
->lock
);
1998 * double_rq_unlock - safely unlock two runqueues
2000 * Note this does not restore interrupts like task_rq_unlock,
2001 * you need to do so manually after calling.
2003 static void double_rq_unlock(struct rq
*rq1
, struct rq
*rq2
)
2004 __releases(rq1
->lock
)
2005 __releases(rq2
->lock
)
2007 spin_unlock(&rq1
->lock
);
2009 spin_unlock(&rq2
->lock
);
2011 __release(rq2
->lock
);
2015 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
2017 static void double_lock_balance(struct rq
*this_rq
, struct rq
*busiest
)
2018 __releases(this_rq
->lock
)
2019 __acquires(busiest
->lock
)
2020 __acquires(this_rq
->lock
)
2022 if (unlikely(!irqs_disabled())) {
2023 /* printk() doesn't work good under rq->lock */
2024 spin_unlock(&this_rq
->lock
);
2027 if (unlikely(!spin_trylock(&busiest
->lock
))) {
2028 if (busiest
< this_rq
) {
2029 spin_unlock(&this_rq
->lock
);
2030 spin_lock(&busiest
->lock
);
2031 spin_lock(&this_rq
->lock
);
2033 spin_lock(&busiest
->lock
);
2038 * If dest_cpu is allowed for this process, migrate the task to it.
2039 * This is accomplished by forcing the cpu_allowed mask to only
2040 * allow dest_cpu, which will force the cpu onto dest_cpu. Then
2041 * the cpu_allowed mask is restored.
2043 static void sched_migrate_task(struct task_struct
*p
, int dest_cpu
)
2045 struct migration_req req
;
2046 unsigned long flags
;
2049 rq
= task_rq_lock(p
, &flags
);
2050 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
)
2051 || unlikely(cpu_is_offline(dest_cpu
)))
2054 /* force the process onto the specified CPU */
2055 if (migrate_task(p
, dest_cpu
, &req
)) {
2056 /* Need to wait for migration thread (might exit: take ref). */
2057 struct task_struct
*mt
= rq
->migration_thread
;
2059 get_task_struct(mt
);
2060 task_rq_unlock(rq
, &flags
);
2061 wake_up_process(mt
);
2062 put_task_struct(mt
);
2063 wait_for_completion(&req
.done
);
2068 task_rq_unlock(rq
, &flags
);
2072 * sched_exec - execve() is a valuable balancing opportunity, because at
2073 * this point the task has the smallest effective memory and cache footprint.
2075 void sched_exec(void)
2077 int new_cpu
, this_cpu
= get_cpu();
2078 new_cpu
= sched_balance_self(this_cpu
, SD_BALANCE_EXEC
);
2080 if (new_cpu
!= this_cpu
)
2081 sched_migrate_task(current
, new_cpu
);
2085 * pull_task - move a task from a remote runqueue to the local runqueue.
2086 * Both runqueues must be locked.
2088 static void pull_task(struct rq
*src_rq
, struct prio_array
*src_array
,
2089 struct task_struct
*p
, struct rq
*this_rq
,
2090 struct prio_array
*this_array
, int this_cpu
)
2092 dequeue_task(p
, src_array
);
2093 dec_nr_running(p
, src_rq
);
2094 set_task_cpu(p
, this_cpu
);
2095 inc_nr_running(p
, this_rq
);
2096 enqueue_task(p
, this_array
);
2097 p
->timestamp
= (p
->timestamp
- src_rq
->most_recent_timestamp
)
2098 + this_rq
->most_recent_timestamp
;
2100 * Note that idle threads have a prio of MAX_PRIO, for this test
2101 * to be always true for them.
2103 if (TASK_PREEMPTS_CURR(p
, this_rq
))
2104 resched_task(this_rq
->curr
);
2108 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
2111 int can_migrate_task(struct task_struct
*p
, struct rq
*rq
, int this_cpu
,
2112 struct sched_domain
*sd
, enum idle_type idle
,
2116 * We do not migrate tasks that are:
2117 * 1) running (obviously), or
2118 * 2) cannot be migrated to this CPU due to cpus_allowed, or
2119 * 3) are cache-hot on their current CPU.
2121 if (!cpu_isset(this_cpu
, p
->cpus_allowed
))
2125 if (task_running(rq
, p
))
2129 * Aggressive migration if:
2130 * 1) task is cache cold, or
2131 * 2) too many balance attempts have failed.
2134 if (sd
->nr_balance_failed
> sd
->cache_nice_tries
) {
2135 #ifdef CONFIG_SCHEDSTATS
2136 if (task_hot(p
, rq
->most_recent_timestamp
, sd
))
2137 schedstat_inc(sd
, lb_hot_gained
[idle
]);
2142 if (task_hot(p
, rq
->most_recent_timestamp
, sd
))
2147 #define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
2150 * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
2151 * load from busiest to this_rq, as part of a balancing operation within
2152 * "domain". Returns the number of tasks moved.
2154 * Called with both runqueues locked.
2156 static int move_tasks(struct rq
*this_rq
, int this_cpu
, struct rq
*busiest
,
2157 unsigned long max_nr_move
, unsigned long max_load_move
,
2158 struct sched_domain
*sd
, enum idle_type idle
,
2161 int idx
, pulled
= 0, pinned
= 0, this_best_prio
, best_prio
,
2162 best_prio_seen
, skip_for_load
;
2163 struct prio_array
*array
, *dst_array
;
2164 struct list_head
*head
, *curr
;
2165 struct task_struct
*tmp
;
2168 if (max_nr_move
== 0 || max_load_move
== 0)
2171 rem_load_move
= max_load_move
;
2173 this_best_prio
= rq_best_prio(this_rq
);
2174 best_prio
= rq_best_prio(busiest
);
2176 * Enable handling of the case where there is more than one task
2177 * with the best priority. If the current running task is one
2178 * of those with prio==best_prio we know it won't be moved
2179 * and therefore it's safe to override the skip (based on load) of
2180 * any task we find with that prio.
2182 best_prio_seen
= best_prio
== busiest
->curr
->prio
;
2185 * We first consider expired tasks. Those will likely not be
2186 * executed in the near future, and they are most likely to
2187 * be cache-cold, thus switching CPUs has the least effect
2190 if (busiest
->expired
->nr_active
) {
2191 array
= busiest
->expired
;
2192 dst_array
= this_rq
->expired
;
2194 array
= busiest
->active
;
2195 dst_array
= this_rq
->active
;
2199 /* Start searching at priority 0: */
2203 idx
= sched_find_first_bit(array
->bitmap
);
2205 idx
= find_next_bit(array
->bitmap
, MAX_PRIO
, idx
);
2206 if (idx
>= MAX_PRIO
) {
2207 if (array
== busiest
->expired
&& busiest
->active
->nr_active
) {
2208 array
= busiest
->active
;
2209 dst_array
= this_rq
->active
;
2215 head
= array
->queue
+ idx
;
2218 tmp
= list_entry(curr
, struct task_struct
, run_list
);
2223 * To help distribute high priority tasks accross CPUs we don't
2224 * skip a task if it will be the highest priority task (i.e. smallest
2225 * prio value) on its new queue regardless of its load weight
2227 skip_for_load
= tmp
->load_weight
> rem_load_move
;
2228 if (skip_for_load
&& idx
< this_best_prio
)
2229 skip_for_load
= !best_prio_seen
&& idx
== best_prio
;
2230 if (skip_for_load
||
2231 !can_migrate_task(tmp
, busiest
, this_cpu
, sd
, idle
, &pinned
)) {
2233 best_prio_seen
|= idx
== best_prio
;
2240 pull_task(busiest
, array
, tmp
, this_rq
, dst_array
, this_cpu
);
2242 rem_load_move
-= tmp
->load_weight
;
2245 * We only want to steal up to the prescribed number of tasks
2246 * and the prescribed amount of weighted load.
2248 if (pulled
< max_nr_move
&& rem_load_move
> 0) {
2249 if (idx
< this_best_prio
)
2250 this_best_prio
= idx
;
2258 * Right now, this is the only place pull_task() is called,
2259 * so we can safely collect pull_task() stats here rather than
2260 * inside pull_task().
2262 schedstat_add(sd
, lb_gained
[idle
], pulled
);
2265 *all_pinned
= pinned
;
2270 * find_busiest_group finds and returns the busiest CPU group within the
2271 * domain. It calculates and returns the amount of weighted load which
2272 * should be moved to restore balance via the imbalance parameter.
2274 static struct sched_group
*
2275 find_busiest_group(struct sched_domain
*sd
, int this_cpu
,
2276 unsigned long *imbalance
, enum idle_type idle
, int *sd_idle
,
2277 cpumask_t
*cpus
, int *balance
)
2279 struct sched_group
*busiest
= NULL
, *this = NULL
, *group
= sd
->groups
;
2280 unsigned long max_load
, avg_load
, total_load
, this_load
, total_pwr
;
2281 unsigned long max_pull
;
2282 unsigned long busiest_load_per_task
, busiest_nr_running
;
2283 unsigned long this_load_per_task
, this_nr_running
;
2285 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2286 int power_savings_balance
= 1;
2287 unsigned long leader_nr_running
= 0, min_load_per_task
= 0;
2288 unsigned long min_nr_running
= ULONG_MAX
;
2289 struct sched_group
*group_min
= NULL
, *group_leader
= NULL
;
2292 max_load
= this_load
= total_load
= total_pwr
= 0;
2293 busiest_load_per_task
= busiest_nr_running
= 0;
2294 this_load_per_task
= this_nr_running
= 0;
2295 if (idle
== NOT_IDLE
)
2296 load_idx
= sd
->busy_idx
;
2297 else if (idle
== NEWLY_IDLE
)
2298 load_idx
= sd
->newidle_idx
;
2300 load_idx
= sd
->idle_idx
;
2303 unsigned long load
, group_capacity
;
2306 unsigned int balance_cpu
= -1, first_idle_cpu
= 0;
2307 unsigned long sum_nr_running
, sum_weighted_load
;
2309 local_group
= cpu_isset(this_cpu
, group
->cpumask
);
2312 balance_cpu
= first_cpu(group
->cpumask
);
2314 /* Tally up the load of all CPUs in the group */
2315 sum_weighted_load
= sum_nr_running
= avg_load
= 0;
2317 for_each_cpu_mask(i
, group
->cpumask
) {
2320 if (!cpu_isset(i
, *cpus
))
2325 if (*sd_idle
&& !idle_cpu(i
))
2328 /* Bias balancing toward cpus of our domain */
2330 if (idle_cpu(i
) && !first_idle_cpu
) {
2335 load
= target_load(i
, load_idx
);
2337 load
= source_load(i
, load_idx
);
2340 sum_nr_running
+= rq
->nr_running
;
2341 sum_weighted_load
+= rq
->raw_weighted_load
;
2345 * First idle cpu or the first cpu(busiest) in this sched group
2346 * is eligible for doing load balancing at this and above
2349 if (local_group
&& balance_cpu
!= this_cpu
&& balance
) {
2354 total_load
+= avg_load
;
2355 total_pwr
+= group
->cpu_power
;
2357 /* Adjust by relative CPU power of the group */
2358 avg_load
= (avg_load
* SCHED_LOAD_SCALE
) / group
->cpu_power
;
2360 group_capacity
= group
->cpu_power
/ SCHED_LOAD_SCALE
;
2363 this_load
= avg_load
;
2365 this_nr_running
= sum_nr_running
;
2366 this_load_per_task
= sum_weighted_load
;
2367 } else if (avg_load
> max_load
&&
2368 sum_nr_running
> group_capacity
) {
2369 max_load
= avg_load
;
2371 busiest_nr_running
= sum_nr_running
;
2372 busiest_load_per_task
= sum_weighted_load
;
2375 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2377 * Busy processors will not participate in power savings
2380 if (idle
== NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2384 * If the local group is idle or completely loaded
2385 * no need to do power savings balance at this domain
2387 if (local_group
&& (this_nr_running
>= group_capacity
||
2389 power_savings_balance
= 0;
2392 * If a group is already running at full capacity or idle,
2393 * don't include that group in power savings calculations
2395 if (!power_savings_balance
|| sum_nr_running
>= group_capacity
2400 * Calculate the group which has the least non-idle load.
2401 * This is the group from where we need to pick up the load
2404 if ((sum_nr_running
< min_nr_running
) ||
2405 (sum_nr_running
== min_nr_running
&&
2406 first_cpu(group
->cpumask
) <
2407 first_cpu(group_min
->cpumask
))) {
2409 min_nr_running
= sum_nr_running
;
2410 min_load_per_task
= sum_weighted_load
/
2415 * Calculate the group which is almost near its
2416 * capacity but still has some space to pick up some load
2417 * from other group and save more power
2419 if (sum_nr_running
<= group_capacity
- 1) {
2420 if (sum_nr_running
> leader_nr_running
||
2421 (sum_nr_running
== leader_nr_running
&&
2422 first_cpu(group
->cpumask
) >
2423 first_cpu(group_leader
->cpumask
))) {
2424 group_leader
= group
;
2425 leader_nr_running
= sum_nr_running
;
2430 group
= group
->next
;
2431 } while (group
!= sd
->groups
);
2433 if (!busiest
|| this_load
>= max_load
|| busiest_nr_running
== 0)
2436 avg_load
= (SCHED_LOAD_SCALE
* total_load
) / total_pwr
;
2438 if (this_load
>= avg_load
||
2439 100*max_load
<= sd
->imbalance_pct
*this_load
)
2442 busiest_load_per_task
/= busiest_nr_running
;
2444 * We're trying to get all the cpus to the average_load, so we don't
2445 * want to push ourselves above the average load, nor do we wish to
2446 * reduce the max loaded cpu below the average load, as either of these
2447 * actions would just result in more rebalancing later, and ping-pong
2448 * tasks around. Thus we look for the minimum possible imbalance.
2449 * Negative imbalances (*we* are more loaded than anyone else) will
2450 * be counted as no imbalance for these purposes -- we can't fix that
2451 * by pulling tasks to us. Be careful of negative numbers as they'll
2452 * appear as very large values with unsigned longs.
2454 if (max_load
<= busiest_load_per_task
)
2458 * In the presence of smp nice balancing, certain scenarios can have
2459 * max load less than avg load(as we skip the groups at or below
2460 * its cpu_power, while calculating max_load..)
2462 if (max_load
< avg_load
) {
2464 goto small_imbalance
;
2467 /* Don't want to pull so many tasks that a group would go idle */
2468 max_pull
= min(max_load
- avg_load
, max_load
- busiest_load_per_task
);
2470 /* How much load to actually move to equalise the imbalance */
2471 *imbalance
= min(max_pull
* busiest
->cpu_power
,
2472 (avg_load
- this_load
) * this->cpu_power
)
2476 * if *imbalance is less than the average load per runnable task
2477 * there is no gaurantee that any tasks will be moved so we'll have
2478 * a think about bumping its value to force at least one task to be
2481 if (*imbalance
< busiest_load_per_task
) {
2482 unsigned long tmp
, pwr_now
, pwr_move
;
2486 pwr_move
= pwr_now
= 0;
2488 if (this_nr_running
) {
2489 this_load_per_task
/= this_nr_running
;
2490 if (busiest_load_per_task
> this_load_per_task
)
2493 this_load_per_task
= SCHED_LOAD_SCALE
;
2495 if (max_load
- this_load
>= busiest_load_per_task
* imbn
) {
2496 *imbalance
= busiest_load_per_task
;
2501 * OK, we don't have enough imbalance to justify moving tasks,
2502 * however we may be able to increase total CPU power used by
2506 pwr_now
+= busiest
->cpu_power
*
2507 min(busiest_load_per_task
, max_load
);
2508 pwr_now
+= this->cpu_power
*
2509 min(this_load_per_task
, this_load
);
2510 pwr_now
/= SCHED_LOAD_SCALE
;
2512 /* Amount of load we'd subtract */
2513 tmp
= busiest_load_per_task
* SCHED_LOAD_SCALE
/
2516 pwr_move
+= busiest
->cpu_power
*
2517 min(busiest_load_per_task
, max_load
- tmp
);
2519 /* Amount of load we'd add */
2520 if (max_load
* busiest
->cpu_power
<
2521 busiest_load_per_task
* SCHED_LOAD_SCALE
)
2522 tmp
= max_load
* busiest
->cpu_power
/ this->cpu_power
;
2524 tmp
= busiest_load_per_task
* SCHED_LOAD_SCALE
/
2526 pwr_move
+= this->cpu_power
*
2527 min(this_load_per_task
, this_load
+ tmp
);
2528 pwr_move
/= SCHED_LOAD_SCALE
;
2530 /* Move if we gain throughput */
2531 if (pwr_move
<= pwr_now
)
2534 *imbalance
= busiest_load_per_task
;
2540 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
2541 if (idle
== NOT_IDLE
|| !(sd
->flags
& SD_POWERSAVINGS_BALANCE
))
2544 if (this == group_leader
&& group_leader
!= group_min
) {
2545 *imbalance
= min_load_per_task
;
2555 * find_busiest_queue - find the busiest runqueue among the cpus in group.
2558 find_busiest_queue(struct sched_group
*group
, enum idle_type idle
,
2559 unsigned long imbalance
, cpumask_t
*cpus
)
2561 struct rq
*busiest
= NULL
, *rq
;
2562 unsigned long max_load
= 0;
2565 for_each_cpu_mask(i
, group
->cpumask
) {
2567 if (!cpu_isset(i
, *cpus
))
2572 if (rq
->nr_running
== 1 && rq
->raw_weighted_load
> imbalance
)
2575 if (rq
->raw_weighted_load
> max_load
) {
2576 max_load
= rq
->raw_weighted_load
;
2585 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
2586 * so long as it is large enough.
2588 #define MAX_PINNED_INTERVAL 512
2590 static inline unsigned long minus_1_or_zero(unsigned long n
)
2592 return n
> 0 ? n
- 1 : 0;
2596 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2597 * tasks if there is an imbalance.
2599 static int load_balance(int this_cpu
, struct rq
*this_rq
,
2600 struct sched_domain
*sd
, enum idle_type idle
,
2603 int nr_moved
, all_pinned
= 0, active_balance
= 0, sd_idle
= 0;
2604 struct sched_group
*group
;
2605 unsigned long imbalance
;
2607 cpumask_t cpus
= CPU_MASK_ALL
;
2608 unsigned long flags
;
2611 * When power savings policy is enabled for the parent domain, idle
2612 * sibling can pick up load irrespective of busy siblings. In this case,
2613 * let the state of idle sibling percolate up as IDLE, instead of
2614 * portraying it as NOT_IDLE.
2616 if (idle
!= NOT_IDLE
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2617 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2620 schedstat_inc(sd
, lb_cnt
[idle
]);
2623 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, idle
, &sd_idle
,
2630 schedstat_inc(sd
, lb_nobusyg
[idle
]);
2634 busiest
= find_busiest_queue(group
, idle
, imbalance
, &cpus
);
2636 schedstat_inc(sd
, lb_nobusyq
[idle
]);
2640 BUG_ON(busiest
== this_rq
);
2642 schedstat_add(sd
, lb_imbalance
[idle
], imbalance
);
2645 if (busiest
->nr_running
> 1) {
2647 * Attempt to move tasks. If find_busiest_group has found
2648 * an imbalance but busiest->nr_running <= 1, the group is
2649 * still unbalanced. nr_moved simply stays zero, so it is
2650 * correctly treated as an imbalance.
2652 local_irq_save(flags
);
2653 double_rq_lock(this_rq
, busiest
);
2654 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2655 minus_1_or_zero(busiest
->nr_running
),
2656 imbalance
, sd
, idle
, &all_pinned
);
2657 double_rq_unlock(this_rq
, busiest
);
2658 local_irq_restore(flags
);
2660 /* All tasks on this runqueue were pinned by CPU affinity */
2661 if (unlikely(all_pinned
)) {
2662 cpu_clear(cpu_of(busiest
), cpus
);
2663 if (!cpus_empty(cpus
))
2670 schedstat_inc(sd
, lb_failed
[idle
]);
2671 sd
->nr_balance_failed
++;
2673 if (unlikely(sd
->nr_balance_failed
> sd
->cache_nice_tries
+2)) {
2675 spin_lock_irqsave(&busiest
->lock
, flags
);
2677 /* don't kick the migration_thread, if the curr
2678 * task on busiest cpu can't be moved to this_cpu
2680 if (!cpu_isset(this_cpu
, busiest
->curr
->cpus_allowed
)) {
2681 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2683 goto out_one_pinned
;
2686 if (!busiest
->active_balance
) {
2687 busiest
->active_balance
= 1;
2688 busiest
->push_cpu
= this_cpu
;
2691 spin_unlock_irqrestore(&busiest
->lock
, flags
);
2693 wake_up_process(busiest
->migration_thread
);
2696 * We've kicked active balancing, reset the failure
2699 sd
->nr_balance_failed
= sd
->cache_nice_tries
+1;
2702 sd
->nr_balance_failed
= 0;
2704 if (likely(!active_balance
)) {
2705 /* We were unbalanced, so reset the balancing interval */
2706 sd
->balance_interval
= sd
->min_interval
;
2709 * If we've begun active balancing, start to back off. This
2710 * case may not be covered by the all_pinned logic if there
2711 * is only 1 task on the busy runqueue (because we don't call
2714 if (sd
->balance_interval
< sd
->max_interval
)
2715 sd
->balance_interval
*= 2;
2718 if (!nr_moved
&& !sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2719 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2724 schedstat_inc(sd
, lb_balanced
[idle
]);
2726 sd
->nr_balance_failed
= 0;
2729 /* tune up the balancing interval */
2730 if ((all_pinned
&& sd
->balance_interval
< MAX_PINNED_INTERVAL
) ||
2731 (sd
->balance_interval
< sd
->max_interval
))
2732 sd
->balance_interval
*= 2;
2734 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2735 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2741 * Check this_cpu to ensure it is balanced within domain. Attempt to move
2742 * tasks if there is an imbalance.
2744 * Called from schedule when this_rq is about to become idle (NEWLY_IDLE).
2745 * this_rq is locked.
2748 load_balance_newidle(int this_cpu
, struct rq
*this_rq
, struct sched_domain
*sd
)
2750 struct sched_group
*group
;
2751 struct rq
*busiest
= NULL
;
2752 unsigned long imbalance
;
2755 cpumask_t cpus
= CPU_MASK_ALL
;
2758 * When power savings policy is enabled for the parent domain, idle
2759 * sibling can pick up load irrespective of busy siblings. In this case,
2760 * let the state of idle sibling percolate up as IDLE, instead of
2761 * portraying it as NOT_IDLE.
2763 if (sd
->flags
& SD_SHARE_CPUPOWER
&&
2764 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2767 schedstat_inc(sd
, lb_cnt
[NEWLY_IDLE
]);
2769 group
= find_busiest_group(sd
, this_cpu
, &imbalance
, NEWLY_IDLE
,
2770 &sd_idle
, &cpus
, NULL
);
2772 schedstat_inc(sd
, lb_nobusyg
[NEWLY_IDLE
]);
2776 busiest
= find_busiest_queue(group
, NEWLY_IDLE
, imbalance
,
2779 schedstat_inc(sd
, lb_nobusyq
[NEWLY_IDLE
]);
2783 BUG_ON(busiest
== this_rq
);
2785 schedstat_add(sd
, lb_imbalance
[NEWLY_IDLE
], imbalance
);
2788 if (busiest
->nr_running
> 1) {
2789 /* Attempt to move tasks */
2790 double_lock_balance(this_rq
, busiest
);
2791 nr_moved
= move_tasks(this_rq
, this_cpu
, busiest
,
2792 minus_1_or_zero(busiest
->nr_running
),
2793 imbalance
, sd
, NEWLY_IDLE
, NULL
);
2794 spin_unlock(&busiest
->lock
);
2797 cpu_clear(cpu_of(busiest
), cpus
);
2798 if (!cpus_empty(cpus
))
2804 schedstat_inc(sd
, lb_failed
[NEWLY_IDLE
]);
2805 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2806 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2809 sd
->nr_balance_failed
= 0;
2814 schedstat_inc(sd
, lb_balanced
[NEWLY_IDLE
]);
2815 if (!sd_idle
&& sd
->flags
& SD_SHARE_CPUPOWER
&&
2816 !test_sd_parent(sd
, SD_POWERSAVINGS_BALANCE
))
2818 sd
->nr_balance_failed
= 0;
2824 * idle_balance is called by schedule() if this_cpu is about to become
2825 * idle. Attempts to pull tasks from other CPUs.
2827 static void idle_balance(int this_cpu
, struct rq
*this_rq
)
2829 struct sched_domain
*sd
;
2830 int pulled_task
= 0;
2831 unsigned long next_balance
= jiffies
+ 60 * HZ
;
2833 for_each_domain(this_cpu
, sd
) {
2834 if (sd
->flags
& SD_BALANCE_NEWIDLE
) {
2835 /* If we've pulled tasks over stop searching: */
2836 pulled_task
= load_balance_newidle(this_cpu
,
2838 if (time_after(next_balance
,
2839 sd
->last_balance
+ sd
->balance_interval
))
2840 next_balance
= sd
->last_balance
2841 + sd
->balance_interval
;
2848 * We are going idle. next_balance may be set based on
2849 * a busy processor. So reset next_balance.
2851 this_rq
->next_balance
= next_balance
;
2855 * active_load_balance is run by migration threads. It pushes running tasks
2856 * off the busiest CPU onto idle CPUs. It requires at least 1 task to be
2857 * running on each physical CPU where possible, and avoids physical /
2858 * logical imbalances.
2860 * Called with busiest_rq locked.
2862 static void active_load_balance(struct rq
*busiest_rq
, int busiest_cpu
)
2864 int target_cpu
= busiest_rq
->push_cpu
;
2865 struct sched_domain
*sd
;
2866 struct rq
*target_rq
;
2868 /* Is there any task to move? */
2869 if (busiest_rq
->nr_running
<= 1)
2872 target_rq
= cpu_rq(target_cpu
);
2875 * This condition is "impossible", if it occurs
2876 * we need to fix it. Originally reported by
2877 * Bjorn Helgaas on a 128-cpu setup.
2879 BUG_ON(busiest_rq
== target_rq
);
2881 /* move a task from busiest_rq to target_rq */
2882 double_lock_balance(busiest_rq
, target_rq
);
2884 /* Search for an sd spanning us and the target CPU. */
2885 for_each_domain(target_cpu
, sd
) {
2886 if ((sd
->flags
& SD_LOAD_BALANCE
) &&
2887 cpu_isset(busiest_cpu
, sd
->span
))
2892 schedstat_inc(sd
, alb_cnt
);
2894 if (move_tasks(target_rq
, target_cpu
, busiest_rq
, 1,
2895 RTPRIO_TO_LOAD_WEIGHT(100), sd
, SCHED_IDLE
,
2897 schedstat_inc(sd
, alb_pushed
);
2899 schedstat_inc(sd
, alb_failed
);
2901 spin_unlock(&target_rq
->lock
);
2904 static void update_load(struct rq
*this_rq
)
2906 unsigned long this_load
;
2907 unsigned int i
, scale
;
2909 this_load
= this_rq
->raw_weighted_load
;
2911 /* Update our load: */
2912 for (i
= 0, scale
= 1; i
< 3; i
++, scale
+= scale
) {
2913 unsigned long old_load
, new_load
;
2915 /* scale is effectively 1 << i now, and >> i divides by scale */
2917 old_load
= this_rq
->cpu_load
[i
];
2918 new_load
= this_load
;
2920 * Round up the averaging division if load is increasing. This
2921 * prevents us from getting stuck on 9 if the load is 10, for
2924 if (new_load
> old_load
)
2925 new_load
+= scale
-1;
2926 this_rq
->cpu_load
[i
] = (old_load
*(scale
-1) + new_load
) >> i
;
2931 * run_rebalance_domains is triggered when needed from the scheduler tick.
2933 * It checks each scheduling domain to see if it is due to be balanced,
2934 * and initiates a balancing operation if so.
2936 * Balancing parameters are set up in arch_init_sched_domains.
2938 static DEFINE_SPINLOCK(balancing
);
2940 static void run_rebalance_domains(struct softirq_action
*h
)
2942 int this_cpu
= smp_processor_id(), balance
= 1;
2943 struct rq
*this_rq
= cpu_rq(this_cpu
);
2944 unsigned long interval
;
2945 struct sched_domain
*sd
;
2947 * We are idle if there are no processes running. This
2948 * is valid even if we are the idle process (SMT).
2950 enum idle_type idle
= !this_rq
->nr_running
?
2951 SCHED_IDLE
: NOT_IDLE
;
2952 /* Earliest time when we have to call run_rebalance_domains again */
2953 unsigned long next_balance
= jiffies
+ 60*HZ
;
2955 for_each_domain(this_cpu
, sd
) {
2956 if (!(sd
->flags
& SD_LOAD_BALANCE
))
2959 interval
= sd
->balance_interval
;
2960 if (idle
!= SCHED_IDLE
)
2961 interval
*= sd
->busy_factor
;
2963 /* scale ms to jiffies */
2964 interval
= msecs_to_jiffies(interval
);
2965 if (unlikely(!interval
))
2968 if (sd
->flags
& SD_SERIALIZE
) {
2969 if (!spin_trylock(&balancing
))
2973 if (time_after_eq(jiffies
, sd
->last_balance
+ interval
)) {
2974 if (load_balance(this_cpu
, this_rq
, sd
, idle
, &balance
)) {
2976 * We've pulled tasks over so either we're no
2977 * longer idle, or one of our SMT siblings is
2982 sd
->last_balance
= jiffies
;
2984 if (sd
->flags
& SD_SERIALIZE
)
2985 spin_unlock(&balancing
);
2987 if (time_after(next_balance
, sd
->last_balance
+ interval
))
2988 next_balance
= sd
->last_balance
+ interval
;
2991 * Stop the load balance at this level. There is another
2992 * CPU in our sched group which is doing load balancing more
2998 this_rq
->next_balance
= next_balance
;
3002 * on UP we do not need to balance between CPUs:
3004 static inline void idle_balance(int cpu
, struct rq
*rq
)
3009 static inline void wake_priority_sleeper(struct rq
*rq
)
3011 #ifdef CONFIG_SCHED_SMT
3012 if (!rq
->nr_running
)
3015 spin_lock(&rq
->lock
);
3017 * If an SMT sibling task has been put to sleep for priority
3018 * reasons reschedule the idle task to see if it can now run.
3021 resched_task(rq
->idle
);
3022 spin_unlock(&rq
->lock
);
3026 DEFINE_PER_CPU(struct kernel_stat
, kstat
);
3028 EXPORT_PER_CPU_SYMBOL(kstat
);
3031 * This is called on clock ticks and on context switches.
3032 * Bank in p->sched_time the ns elapsed since the last tick or switch.
3035 update_cpu_clock(struct task_struct
*p
, struct rq
*rq
, unsigned long long now
)
3037 p
->sched_time
+= now
- p
->last_ran
;
3038 p
->last_ran
= rq
->most_recent_timestamp
= now
;
3042 * Return current->sched_time plus any more ns on the sched_clock
3043 * that have not yet been banked.
3045 unsigned long long current_sched_time(const struct task_struct
*p
)
3047 unsigned long long ns
;
3048 unsigned long flags
;
3050 local_irq_save(flags
);
3051 ns
= p
->sched_time
+ sched_clock() - p
->last_ran
;
3052 local_irq_restore(flags
);
3058 * We place interactive tasks back into the active array, if possible.
3060 * To guarantee that this does not starve expired tasks we ignore the
3061 * interactivity of a task if the first expired task had to wait more
3062 * than a 'reasonable' amount of time. This deadline timeout is
3063 * load-dependent, as the frequency of array switched decreases with
3064 * increasing number of running tasks. We also ignore the interactivity
3065 * if a better static_prio task has expired:
3067 static inline int expired_starving(struct rq
*rq
)
3069 if (rq
->curr
->static_prio
> rq
->best_expired_prio
)
3071 if (!STARVATION_LIMIT
|| !rq
->expired_timestamp
)
3073 if (jiffies
- rq
->expired_timestamp
> STARVATION_LIMIT
* rq
->nr_running
)
3079 * Account user cpu time to a process.
3080 * @p: the process that the cpu time gets accounted to
3081 * @hardirq_offset: the offset to subtract from hardirq_count()
3082 * @cputime: the cpu time spent in user space since the last update
3084 void account_user_time(struct task_struct
*p
, cputime_t cputime
)
3086 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3089 p
->utime
= cputime_add(p
->utime
, cputime
);
3091 /* Add user time to cpustat. */
3092 tmp
= cputime_to_cputime64(cputime
);
3093 if (TASK_NICE(p
) > 0)
3094 cpustat
->nice
= cputime64_add(cpustat
->nice
, tmp
);
3096 cpustat
->user
= cputime64_add(cpustat
->user
, tmp
);
3100 * Account system cpu time to a process.
3101 * @p: the process that the cpu time gets accounted to
3102 * @hardirq_offset: the offset to subtract from hardirq_count()
3103 * @cputime: the cpu time spent in kernel space since the last update
3105 void account_system_time(struct task_struct
*p
, int hardirq_offset
,
3108 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3109 struct rq
*rq
= this_rq();
3112 p
->stime
= cputime_add(p
->stime
, cputime
);
3114 /* Add system time to cpustat. */
3115 tmp
= cputime_to_cputime64(cputime
);
3116 if (hardirq_count() - hardirq_offset
)
3117 cpustat
->irq
= cputime64_add(cpustat
->irq
, tmp
);
3118 else if (softirq_count())
3119 cpustat
->softirq
= cputime64_add(cpustat
->softirq
, tmp
);
3120 else if (p
!= rq
->idle
)
3121 cpustat
->system
= cputime64_add(cpustat
->system
, tmp
);
3122 else if (atomic_read(&rq
->nr_iowait
) > 0)
3123 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3125 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3126 /* Account for system time used */
3127 acct_update_integrals(p
);
3131 * Account for involuntary wait time.
3132 * @p: the process from which the cpu time has been stolen
3133 * @steal: the cpu time spent in involuntary wait
3135 void account_steal_time(struct task_struct
*p
, cputime_t steal
)
3137 struct cpu_usage_stat
*cpustat
= &kstat_this_cpu
.cpustat
;
3138 cputime64_t tmp
= cputime_to_cputime64(steal
);
3139 struct rq
*rq
= this_rq();
3141 if (p
== rq
->idle
) {
3142 p
->stime
= cputime_add(p
->stime
, steal
);
3143 if (atomic_read(&rq
->nr_iowait
) > 0)
3144 cpustat
->iowait
= cputime64_add(cpustat
->iowait
, tmp
);
3146 cpustat
->idle
= cputime64_add(cpustat
->idle
, tmp
);
3148 cpustat
->steal
= cputime64_add(cpustat
->steal
, tmp
);
3151 static void task_running_tick(struct rq
*rq
, struct task_struct
*p
)
3153 if (p
->array
!= rq
->active
) {
3154 /* Task has expired but was not scheduled yet */
3155 set_tsk_need_resched(p
);
3158 spin_lock(&rq
->lock
);
3160 * The task was running during this tick - update the
3161 * time slice counter. Note: we do not update a thread's
3162 * priority until it either goes to sleep or uses up its
3163 * timeslice. This makes it possible for interactive tasks
3164 * to use up their timeslices at their highest priority levels.
3168 * RR tasks need a special form of timeslice management.
3169 * FIFO tasks have no timeslices.
3171 if ((p
->policy
== SCHED_RR
) && !--p
->time_slice
) {
3172 p
->time_slice
= task_timeslice(p
);
3173 p
->first_time_slice
= 0;
3174 set_tsk_need_resched(p
);
3176 /* put it at the end of the queue: */
3177 requeue_task(p
, rq
->active
);
3181 if (!--p
->time_slice
) {
3182 dequeue_task(p
, rq
->active
);
3183 set_tsk_need_resched(p
);
3184 p
->prio
= effective_prio(p
);
3185 p
->time_slice
= task_timeslice(p
);
3186 p
->first_time_slice
= 0;
3188 if (!rq
->expired_timestamp
)
3189 rq
->expired_timestamp
= jiffies
;
3190 if (!TASK_INTERACTIVE(p
) || expired_starving(rq
)) {
3191 enqueue_task(p
, rq
->expired
);
3192 if (p
->static_prio
< rq
->best_expired_prio
)
3193 rq
->best_expired_prio
= p
->static_prio
;
3195 enqueue_task(p
, rq
->active
);
3198 * Prevent a too long timeslice allowing a task to monopolize
3199 * the CPU. We do this by splitting up the timeslice into
3202 * Note: this does not mean the task's timeslices expire or
3203 * get lost in any way, they just might be preempted by
3204 * another task of equal priority. (one with higher
3205 * priority would have preempted this task already.) We
3206 * requeue this task to the end of the list on this priority
3207 * level, which is in essence a round-robin of tasks with
3210 * This only applies to tasks in the interactive
3211 * delta range with at least TIMESLICE_GRANULARITY to requeue.
3213 if (TASK_INTERACTIVE(p
) && !((task_timeslice(p
) -
3214 p
->time_slice
) % TIMESLICE_GRANULARITY(p
)) &&
3215 (p
->time_slice
>= TIMESLICE_GRANULARITY(p
)) &&
3216 (p
->array
== rq
->active
)) {
3218 requeue_task(p
, rq
->active
);
3219 set_tsk_need_resched(p
);
3223 spin_unlock(&rq
->lock
);
3227 * This function gets called by the timer code, with HZ frequency.
3228 * We call it with interrupts disabled.
3230 * It also gets called by the fork code, when changing the parent's
3233 void scheduler_tick(void)
3235 unsigned long long now
= sched_clock();
3236 struct task_struct
*p
= current
;
3237 int cpu
= smp_processor_id();
3238 struct rq
*rq
= cpu_rq(cpu
);
3240 update_cpu_clock(p
, rq
, now
);
3243 /* Task on the idle queue */
3244 wake_priority_sleeper(rq
);
3246 task_running_tick(rq
, p
);
3249 if (time_after_eq(jiffies
, rq
->next_balance
))
3250 raise_softirq(SCHED_SOFTIRQ
);
3254 #ifdef CONFIG_SCHED_SMT
3255 static inline void wakeup_busy_runqueue(struct rq
*rq
)
3257 /* If an SMT runqueue is sleeping due to priority reasons wake it up */
3258 if (rq
->curr
== rq
->idle
&& rq
->nr_running
)
3259 resched_task(rq
->idle
);
3263 * Called with interrupt disabled and this_rq's runqueue locked.
3265 static void wake_sleeping_dependent(int this_cpu
)
3267 struct sched_domain
*tmp
, *sd
= NULL
;
3270 for_each_domain(this_cpu
, tmp
) {
3271 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
3280 for_each_cpu_mask(i
, sd
->span
) {
3281 struct rq
*smt_rq
= cpu_rq(i
);
3285 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
3288 wakeup_busy_runqueue(smt_rq
);
3289 spin_unlock(&smt_rq
->lock
);
3294 * number of 'lost' timeslices this task wont be able to fully
3295 * utilize, if another task runs on a sibling. This models the
3296 * slowdown effect of other tasks running on siblings:
3298 static inline unsigned long
3299 smt_slice(struct task_struct
*p
, struct sched_domain
*sd
)
3301 return p
->time_slice
* (100 - sd
->per_cpu_gain
) / 100;
3305 * To minimise lock contention and not have to drop this_rq's runlock we only
3306 * trylock the sibling runqueues and bypass those runqueues if we fail to
3307 * acquire their lock. As we only trylock the normal locking order does not
3308 * need to be obeyed.
3311 dependent_sleeper(int this_cpu
, struct rq
*this_rq
, struct task_struct
*p
)
3313 struct sched_domain
*tmp
, *sd
= NULL
;
3316 /* kernel/rt threads do not participate in dependent sleeping */
3317 if (!p
->mm
|| rt_task(p
))
3320 for_each_domain(this_cpu
, tmp
) {
3321 if (tmp
->flags
& SD_SHARE_CPUPOWER
) {
3330 for_each_cpu_mask(i
, sd
->span
) {
3331 struct task_struct
*smt_curr
;
3338 if (unlikely(!spin_trylock(&smt_rq
->lock
)))
3341 smt_curr
= smt_rq
->curr
;
3347 * If a user task with lower static priority than the
3348 * running task on the SMT sibling is trying to schedule,
3349 * delay it till there is proportionately less timeslice
3350 * left of the sibling task to prevent a lower priority
3351 * task from using an unfair proportion of the
3352 * physical cpu's resources. -ck
3354 if (rt_task(smt_curr
)) {
3356 * With real time tasks we run non-rt tasks only
3357 * per_cpu_gain% of the time.
3359 if ((jiffies
% DEF_TIMESLICE
) >
3360 (sd
->per_cpu_gain
* DEF_TIMESLICE
/ 100))
3363 if (smt_curr
->static_prio
< p
->static_prio
&&
3364 !TASK_PREEMPTS_CURR(p
, smt_rq
) &&
3365 smt_slice(smt_curr
, sd
) > task_timeslice(p
))
3369 spin_unlock(&smt_rq
->lock
);
3374 static inline void wake_sleeping_dependent(int this_cpu
)
3378 dependent_sleeper(int this_cpu
, struct rq
*this_rq
, struct task_struct
*p
)
3384 #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
3386 void fastcall
add_preempt_count(int val
)
3391 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3393 preempt_count() += val
;
3395 * Spinlock count overflowing soon?
3397 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK
) >=
3400 EXPORT_SYMBOL(add_preempt_count
);
3402 void fastcall
sub_preempt_count(int val
)
3407 if (DEBUG_LOCKS_WARN_ON(val
> preempt_count()))
3410 * Is the spinlock portion underflowing?
3412 if (DEBUG_LOCKS_WARN_ON((val
< PREEMPT_MASK
) &&
3413 !(preempt_count() & PREEMPT_MASK
)))
3416 preempt_count() -= val
;
3418 EXPORT_SYMBOL(sub_preempt_count
);
3422 static inline int interactive_sleep(enum sleep_type sleep_type
)
3424 return (sleep_type
== SLEEP_INTERACTIVE
||
3425 sleep_type
== SLEEP_INTERRUPTED
);
3429 * schedule() is the main scheduler function.
3431 asmlinkage
void __sched
schedule(void)
3433 struct task_struct
*prev
, *next
;
3434 struct prio_array
*array
;
3435 struct list_head
*queue
;
3436 unsigned long long now
;
3437 unsigned long run_time
;
3438 int cpu
, idx
, new_prio
;
3443 * Test if we are atomic. Since do_exit() needs to call into
3444 * schedule() atomically, we ignore that path for now.
3445 * Otherwise, whine if we are scheduling when we should not be.
3447 if (unlikely(in_atomic() && !current
->exit_state
)) {
3448 printk(KERN_ERR
"BUG: scheduling while atomic: "
3450 current
->comm
, preempt_count(), current
->pid
);
3451 debug_show_held_locks(current
);
3452 if (irqs_disabled())
3453 print_irqtrace_events(current
);
3456 profile_hit(SCHED_PROFILING
, __builtin_return_address(0));
3461 release_kernel_lock(prev
);
3462 need_resched_nonpreemptible
:
3466 * The idle thread is not allowed to schedule!
3467 * Remove this check after it has been exercised a bit.
3469 if (unlikely(prev
== rq
->idle
) && prev
->state
!= TASK_RUNNING
) {
3470 printk(KERN_ERR
"bad: scheduling from the idle thread!\n");
3474 schedstat_inc(rq
, sched_cnt
);
3475 now
= sched_clock();
3476 if (likely((long long)(now
- prev
->timestamp
) < NS_MAX_SLEEP_AVG
)) {
3477 run_time
= now
- prev
->timestamp
;
3478 if (unlikely((long long)(now
- prev
->timestamp
) < 0))
3481 run_time
= NS_MAX_SLEEP_AVG
;
3484 * Tasks charged proportionately less run_time at high sleep_avg to
3485 * delay them losing their interactive status
3487 run_time
/= (CURRENT_BONUS(prev
) ? : 1);
3489 spin_lock_irq(&rq
->lock
);
3491 switch_count
= &prev
->nivcsw
;
3492 if (prev
->state
&& !(preempt_count() & PREEMPT_ACTIVE
)) {
3493 switch_count
= &prev
->nvcsw
;
3494 if (unlikely((prev
->state
& TASK_INTERRUPTIBLE
) &&
3495 unlikely(signal_pending(prev
))))
3496 prev
->state
= TASK_RUNNING
;
3498 if (prev
->state
== TASK_UNINTERRUPTIBLE
)
3499 rq
->nr_uninterruptible
++;
3500 deactivate_task(prev
, rq
);
3504 cpu
= smp_processor_id();
3505 if (unlikely(!rq
->nr_running
)) {
3506 idle_balance(cpu
, rq
);
3507 if (!rq
->nr_running
) {
3509 rq
->expired_timestamp
= 0;
3510 wake_sleeping_dependent(cpu
);
3516 if (unlikely(!array
->nr_active
)) {
3518 * Switch the active and expired arrays.
3520 schedstat_inc(rq
, sched_switch
);
3521 rq
->active
= rq
->expired
;
3522 rq
->expired
= array
;
3524 rq
->expired_timestamp
= 0;
3525 rq
->best_expired_prio
= MAX_PRIO
;
3528 idx
= sched_find_first_bit(array
->bitmap
);
3529 queue
= array
->queue
+ idx
;
3530 next
= list_entry(queue
->next
, struct task_struct
, run_list
);
3532 if (!rt_task(next
) && interactive_sleep(next
->sleep_type
)) {
3533 unsigned long long delta
= now
- next
->timestamp
;
3534 if (unlikely((long long)(now
- next
->timestamp
) < 0))
3537 if (next
->sleep_type
== SLEEP_INTERACTIVE
)
3538 delta
= delta
* (ON_RUNQUEUE_WEIGHT
* 128 / 100) / 128;
3540 array
= next
->array
;
3541 new_prio
= recalc_task_prio(next
, next
->timestamp
+ delta
);
3543 if (unlikely(next
->prio
!= new_prio
)) {
3544 dequeue_task(next
, array
);
3545 next
->prio
= new_prio
;
3546 enqueue_task(next
, array
);
3549 next
->sleep_type
= SLEEP_NORMAL
;
3550 if (dependent_sleeper(cpu
, rq
, next
))
3553 if (next
== rq
->idle
)
3554 schedstat_inc(rq
, sched_goidle
);
3556 prefetch_stack(next
);
3557 clear_tsk_need_resched(prev
);
3558 rcu_qsctr_inc(task_cpu(prev
));
3560 update_cpu_clock(prev
, rq
, now
);
3562 prev
->sleep_avg
-= run_time
;
3563 if ((long)prev
->sleep_avg
<= 0)
3564 prev
->sleep_avg
= 0;
3565 prev
->timestamp
= prev
->last_ran
= now
;
3567 sched_info_switch(prev
, next
);
3568 if (likely(prev
!= next
)) {
3569 next
->timestamp
= now
;
3574 prepare_task_switch(rq
, next
);
3575 prev
= context_switch(rq
, prev
, next
);
3578 * this_rq must be evaluated again because prev may have moved
3579 * CPUs since it called schedule(), thus the 'rq' on its stack
3580 * frame will be invalid.
3582 finish_task_switch(this_rq(), prev
);
3584 spin_unlock_irq(&rq
->lock
);
3587 if (unlikely(reacquire_kernel_lock(prev
) < 0))
3588 goto need_resched_nonpreemptible
;
3589 preempt_enable_no_resched();
3590 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3593 EXPORT_SYMBOL(schedule
);
3595 #ifdef CONFIG_PREEMPT
3597 * this is the entry point to schedule() from in-kernel preemption
3598 * off of preempt_enable. Kernel preemptions off return from interrupt
3599 * occur there and call schedule directly.
3601 asmlinkage
void __sched
preempt_schedule(void)
3603 struct thread_info
*ti
= current_thread_info();
3604 #ifdef CONFIG_PREEMPT_BKL
3605 struct task_struct
*task
= current
;
3606 int saved_lock_depth
;
3609 * If there is a non-zero preempt_count or interrupts are disabled,
3610 * we do not want to preempt the current task. Just return..
3612 if (likely(ti
->preempt_count
|| irqs_disabled()))
3616 add_preempt_count(PREEMPT_ACTIVE
);
3618 * We keep the big kernel semaphore locked, but we
3619 * clear ->lock_depth so that schedule() doesnt
3620 * auto-release the semaphore:
3622 #ifdef CONFIG_PREEMPT_BKL
3623 saved_lock_depth
= task
->lock_depth
;
3624 task
->lock_depth
= -1;
3627 #ifdef CONFIG_PREEMPT_BKL
3628 task
->lock_depth
= saved_lock_depth
;
3630 sub_preempt_count(PREEMPT_ACTIVE
);
3632 /* we could miss a preemption opportunity between schedule and now */
3634 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3637 EXPORT_SYMBOL(preempt_schedule
);
3640 * this is the entry point to schedule() from kernel preemption
3641 * off of irq context.
3642 * Note, that this is called and return with irqs disabled. This will
3643 * protect us against recursive calling from irq.
3645 asmlinkage
void __sched
preempt_schedule_irq(void)
3647 struct thread_info
*ti
= current_thread_info();
3648 #ifdef CONFIG_PREEMPT_BKL
3649 struct task_struct
*task
= current
;
3650 int saved_lock_depth
;
3652 /* Catch callers which need to be fixed */
3653 BUG_ON(ti
->preempt_count
|| !irqs_disabled());
3656 add_preempt_count(PREEMPT_ACTIVE
);
3658 * We keep the big kernel semaphore locked, but we
3659 * clear ->lock_depth so that schedule() doesnt
3660 * auto-release the semaphore:
3662 #ifdef CONFIG_PREEMPT_BKL
3663 saved_lock_depth
= task
->lock_depth
;
3664 task
->lock_depth
= -1;
3668 local_irq_disable();
3669 #ifdef CONFIG_PREEMPT_BKL
3670 task
->lock_depth
= saved_lock_depth
;
3672 sub_preempt_count(PREEMPT_ACTIVE
);
3674 /* we could miss a preemption opportunity between schedule and now */
3676 if (unlikely(test_thread_flag(TIF_NEED_RESCHED
)))
3680 #endif /* CONFIG_PREEMPT */
3682 int default_wake_function(wait_queue_t
*curr
, unsigned mode
, int sync
,
3685 return try_to_wake_up(curr
->private, mode
, sync
);
3687 EXPORT_SYMBOL(default_wake_function
);
3690 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3691 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3692 * number) then we wake all the non-exclusive tasks and one exclusive task.
3694 * There are circumstances in which we can try to wake a task which has already
3695 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3696 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3698 static void __wake_up_common(wait_queue_head_t
*q
, unsigned int mode
,
3699 int nr_exclusive
, int sync
, void *key
)
3701 struct list_head
*tmp
, *next
;
3703 list_for_each_safe(tmp
, next
, &q
->task_list
) {
3704 wait_queue_t
*curr
= list_entry(tmp
, wait_queue_t
, task_list
);
3705 unsigned flags
= curr
->flags
;
3707 if (curr
->func(curr
, mode
, sync
, key
) &&
3708 (flags
& WQ_FLAG_EXCLUSIVE
) && !--nr_exclusive
)
3714 * __wake_up - wake up threads blocked on a waitqueue.
3716 * @mode: which threads
3717 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3718 * @key: is directly passed to the wakeup function
3720 void fastcall
__wake_up(wait_queue_head_t
*q
, unsigned int mode
,
3721 int nr_exclusive
, void *key
)
3723 unsigned long flags
;
3725 spin_lock_irqsave(&q
->lock
, flags
);
3726 __wake_up_common(q
, mode
, nr_exclusive
, 0, key
);
3727 spin_unlock_irqrestore(&q
->lock
, flags
);
3729 EXPORT_SYMBOL(__wake_up
);
3732 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3734 void fastcall
__wake_up_locked(wait_queue_head_t
*q
, unsigned int mode
)
3736 __wake_up_common(q
, mode
, 1, 0, NULL
);
3740 * __wake_up_sync - wake up threads blocked on a waitqueue.
3742 * @mode: which threads
3743 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3745 * The sync wakeup differs that the waker knows that it will schedule
3746 * away soon, so while the target thread will be woken up, it will not
3747 * be migrated to another CPU - ie. the two threads are 'synchronized'
3748 * with each other. This can prevent needless bouncing between CPUs.
3750 * On UP it can prevent extra preemption.
3753 __wake_up_sync(wait_queue_head_t
*q
, unsigned int mode
, int nr_exclusive
)
3755 unsigned long flags
;
3761 if (unlikely(!nr_exclusive
))
3764 spin_lock_irqsave(&q
->lock
, flags
);
3765 __wake_up_common(q
, mode
, nr_exclusive
, sync
, NULL
);
3766 spin_unlock_irqrestore(&q
->lock
, flags
);
3768 EXPORT_SYMBOL_GPL(__wake_up_sync
); /* For internal use only */
3770 void fastcall
complete(struct completion
*x
)
3772 unsigned long flags
;
3774 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3776 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3778 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3780 EXPORT_SYMBOL(complete
);
3782 void fastcall
complete_all(struct completion
*x
)
3784 unsigned long flags
;
3786 spin_lock_irqsave(&x
->wait
.lock
, flags
);
3787 x
->done
+= UINT_MAX
/2;
3788 __wake_up_common(&x
->wait
, TASK_UNINTERRUPTIBLE
| TASK_INTERRUPTIBLE
,
3790 spin_unlock_irqrestore(&x
->wait
.lock
, flags
);
3792 EXPORT_SYMBOL(complete_all
);
3794 void fastcall __sched
wait_for_completion(struct completion
*x
)
3798 spin_lock_irq(&x
->wait
.lock
);
3800 DECLARE_WAITQUEUE(wait
, current
);
3802 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3803 __add_wait_queue_tail(&x
->wait
, &wait
);
3805 __set_current_state(TASK_UNINTERRUPTIBLE
);
3806 spin_unlock_irq(&x
->wait
.lock
);
3808 spin_lock_irq(&x
->wait
.lock
);
3810 __remove_wait_queue(&x
->wait
, &wait
);
3813 spin_unlock_irq(&x
->wait
.lock
);
3815 EXPORT_SYMBOL(wait_for_completion
);
3817 unsigned long fastcall __sched
3818 wait_for_completion_timeout(struct completion
*x
, unsigned long timeout
)
3822 spin_lock_irq(&x
->wait
.lock
);
3824 DECLARE_WAITQUEUE(wait
, current
);
3826 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3827 __add_wait_queue_tail(&x
->wait
, &wait
);
3829 __set_current_state(TASK_UNINTERRUPTIBLE
);
3830 spin_unlock_irq(&x
->wait
.lock
);
3831 timeout
= schedule_timeout(timeout
);
3832 spin_lock_irq(&x
->wait
.lock
);
3834 __remove_wait_queue(&x
->wait
, &wait
);
3838 __remove_wait_queue(&x
->wait
, &wait
);
3842 spin_unlock_irq(&x
->wait
.lock
);
3845 EXPORT_SYMBOL(wait_for_completion_timeout
);
3847 int fastcall __sched
wait_for_completion_interruptible(struct completion
*x
)
3853 spin_lock_irq(&x
->wait
.lock
);
3855 DECLARE_WAITQUEUE(wait
, current
);
3857 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3858 __add_wait_queue_tail(&x
->wait
, &wait
);
3860 if (signal_pending(current
)) {
3862 __remove_wait_queue(&x
->wait
, &wait
);
3865 __set_current_state(TASK_INTERRUPTIBLE
);
3866 spin_unlock_irq(&x
->wait
.lock
);
3868 spin_lock_irq(&x
->wait
.lock
);
3870 __remove_wait_queue(&x
->wait
, &wait
);
3874 spin_unlock_irq(&x
->wait
.lock
);
3878 EXPORT_SYMBOL(wait_for_completion_interruptible
);
3880 unsigned long fastcall __sched
3881 wait_for_completion_interruptible_timeout(struct completion
*x
,
3882 unsigned long timeout
)
3886 spin_lock_irq(&x
->wait
.lock
);
3888 DECLARE_WAITQUEUE(wait
, current
);
3890 wait
.flags
|= WQ_FLAG_EXCLUSIVE
;
3891 __add_wait_queue_tail(&x
->wait
, &wait
);
3893 if (signal_pending(current
)) {
3894 timeout
= -ERESTARTSYS
;
3895 __remove_wait_queue(&x
->wait
, &wait
);
3898 __set_current_state(TASK_INTERRUPTIBLE
);
3899 spin_unlock_irq(&x
->wait
.lock
);
3900 timeout
= schedule_timeout(timeout
);
3901 spin_lock_irq(&x
->wait
.lock
);
3903 __remove_wait_queue(&x
->wait
, &wait
);
3907 __remove_wait_queue(&x
->wait
, &wait
);
3911 spin_unlock_irq(&x
->wait
.lock
);
3914 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout
);
3917 #define SLEEP_ON_VAR \
3918 unsigned long flags; \
3919 wait_queue_t wait; \
3920 init_waitqueue_entry(&wait, current);
3922 #define SLEEP_ON_HEAD \
3923 spin_lock_irqsave(&q->lock,flags); \
3924 __add_wait_queue(q, &wait); \
3925 spin_unlock(&q->lock);
3927 #define SLEEP_ON_TAIL \
3928 spin_lock_irq(&q->lock); \
3929 __remove_wait_queue(q, &wait); \
3930 spin_unlock_irqrestore(&q->lock, flags);
3932 void fastcall __sched
interruptible_sleep_on(wait_queue_head_t
*q
)
3936 current
->state
= TASK_INTERRUPTIBLE
;
3942 EXPORT_SYMBOL(interruptible_sleep_on
);
3944 long fastcall __sched
3945 interruptible_sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3949 current
->state
= TASK_INTERRUPTIBLE
;
3952 timeout
= schedule_timeout(timeout
);
3957 EXPORT_SYMBOL(interruptible_sleep_on_timeout
);
3959 void fastcall __sched
sleep_on(wait_queue_head_t
*q
)
3963 current
->state
= TASK_UNINTERRUPTIBLE
;
3969 EXPORT_SYMBOL(sleep_on
);
3971 long fastcall __sched
sleep_on_timeout(wait_queue_head_t
*q
, long timeout
)
3975 current
->state
= TASK_UNINTERRUPTIBLE
;
3978 timeout
= schedule_timeout(timeout
);
3984 EXPORT_SYMBOL(sleep_on_timeout
);
3986 #ifdef CONFIG_RT_MUTEXES
3989 * rt_mutex_setprio - set the current priority of a task
3991 * @prio: prio value (kernel-internal form)
3993 * This function changes the 'effective' priority of a task. It does
3994 * not touch ->normal_prio like __setscheduler().
3996 * Used by the rt_mutex code to implement priority inheritance logic.
3998 void rt_mutex_setprio(struct task_struct
*p
, int prio
)
4000 struct prio_array
*array
;
4001 unsigned long flags
;
4005 BUG_ON(prio
< 0 || prio
> MAX_PRIO
);
4007 rq
= task_rq_lock(p
, &flags
);
4012 dequeue_task(p
, array
);
4017 * If changing to an RT priority then queue it
4018 * in the active array!
4022 enqueue_task(p
, array
);
4024 * Reschedule if we are currently running on this runqueue and
4025 * our priority decreased, or if we are not currently running on
4026 * this runqueue and our priority is higher than the current's
4028 if (task_running(rq
, p
)) {
4029 if (p
->prio
> oldprio
)
4030 resched_task(rq
->curr
);
4031 } else if (TASK_PREEMPTS_CURR(p
, rq
))
4032 resched_task(rq
->curr
);
4034 task_rq_unlock(rq
, &flags
);
4039 void set_user_nice(struct task_struct
*p
, long nice
)
4041 struct prio_array
*array
;
4042 int old_prio
, delta
;
4043 unsigned long flags
;
4046 if (TASK_NICE(p
) == nice
|| nice
< -20 || nice
> 19)
4049 * We have to be careful, if called from sys_setpriority(),
4050 * the task might be in the middle of scheduling on another CPU.
4052 rq
= task_rq_lock(p
, &flags
);
4054 * The RT priorities are set via sched_setscheduler(), but we still
4055 * allow the 'normal' nice value to be set - but as expected
4056 * it wont have any effect on scheduling until the task is
4057 * not SCHED_NORMAL/SCHED_BATCH:
4059 if (has_rt_policy(p
)) {
4060 p
->static_prio
= NICE_TO_PRIO(nice
);
4065 dequeue_task(p
, array
);
4066 dec_raw_weighted_load(rq
, p
);
4069 p
->static_prio
= NICE_TO_PRIO(nice
);
4072 p
->prio
= effective_prio(p
);
4073 delta
= p
->prio
- old_prio
;
4076 enqueue_task(p
, array
);
4077 inc_raw_weighted_load(rq
, p
);
4079 * If the task increased its priority or is running and
4080 * lowered its priority, then reschedule its CPU:
4082 if (delta
< 0 || (delta
> 0 && task_running(rq
, p
)))
4083 resched_task(rq
->curr
);
4086 task_rq_unlock(rq
, &flags
);
4088 EXPORT_SYMBOL(set_user_nice
);
4091 * can_nice - check if a task can reduce its nice value
4095 int can_nice(const struct task_struct
*p
, const int nice
)
4097 /* convert nice value [19,-20] to rlimit style value [1,40] */
4098 int nice_rlim
= 20 - nice
;
4100 return (nice_rlim
<= p
->signal
->rlim
[RLIMIT_NICE
].rlim_cur
||
4101 capable(CAP_SYS_NICE
));
4104 #ifdef __ARCH_WANT_SYS_NICE
4107 * sys_nice - change the priority of the current process.
4108 * @increment: priority increment
4110 * sys_setpriority is a more generic, but much slower function that
4111 * does similar things.
4113 asmlinkage
long sys_nice(int increment
)
4118 * Setpriority might change our priority at the same moment.
4119 * We don't have to worry. Conceptually one call occurs first
4120 * and we have a single winner.
4122 if (increment
< -40)
4127 nice
= PRIO_TO_NICE(current
->static_prio
) + increment
;
4133 if (increment
< 0 && !can_nice(current
, nice
))
4136 retval
= security_task_setnice(current
, nice
);
4140 set_user_nice(current
, nice
);
4147 * task_prio - return the priority value of a given task.
4148 * @p: the task in question.
4150 * This is the priority value as seen by users in /proc.
4151 * RT tasks are offset by -200. Normal tasks are centered
4152 * around 0, value goes from -16 to +15.
4154 int task_prio(const struct task_struct
*p
)
4156 return p
->prio
- MAX_RT_PRIO
;
4160 * task_nice - return the nice value of a given task.
4161 * @p: the task in question.
4163 int task_nice(const struct task_struct
*p
)
4165 return TASK_NICE(p
);
4167 EXPORT_SYMBOL_GPL(task_nice
);
4170 * idle_cpu - is a given cpu idle currently?
4171 * @cpu: the processor in question.
4173 int idle_cpu(int cpu
)
4175 return cpu_curr(cpu
) == cpu_rq(cpu
)->idle
;
4179 * idle_task - return the idle task for a given cpu.
4180 * @cpu: the processor in question.
4182 struct task_struct
*idle_task(int cpu
)
4184 return cpu_rq(cpu
)->idle
;
4188 * find_process_by_pid - find a process with a matching PID value.
4189 * @pid: the pid in question.
4191 static inline struct task_struct
*find_process_by_pid(pid_t pid
)
4193 return pid
? find_task_by_pid(pid
) : current
;
4196 /* Actually do priority change: must hold rq lock. */
4197 static void __setscheduler(struct task_struct
*p
, int policy
, int prio
)
4202 p
->rt_priority
= prio
;
4203 p
->normal_prio
= normal_prio(p
);
4204 /* we are holding p->pi_lock already */
4205 p
->prio
= rt_mutex_getprio(p
);
4207 * SCHED_BATCH tasks are treated as perpetual CPU hogs:
4209 if (policy
== SCHED_BATCH
)
4215 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4216 * @p: the task in question.
4217 * @policy: new policy.
4218 * @param: structure containing the new RT priority.
4220 * NOTE that the task may be already dead.
4222 int sched_setscheduler(struct task_struct
*p
, int policy
,
4223 struct sched_param
*param
)
4225 int retval
, oldprio
, oldpolicy
= -1;
4226 struct prio_array
*array
;
4227 unsigned long flags
;
4230 /* may grab non-irq protected spin_locks */
4231 BUG_ON(in_interrupt());
4233 /* double check policy once rq lock held */
4235 policy
= oldpolicy
= p
->policy
;
4236 else if (policy
!= SCHED_FIFO
&& policy
!= SCHED_RR
&&
4237 policy
!= SCHED_NORMAL
&& policy
!= SCHED_BATCH
)
4240 * Valid priorities for SCHED_FIFO and SCHED_RR are
4241 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and
4244 if (param
->sched_priority
< 0 ||
4245 (p
->mm
&& param
->sched_priority
> MAX_USER_RT_PRIO
-1) ||
4246 (!p
->mm
&& param
->sched_priority
> MAX_RT_PRIO
-1))
4248 if (is_rt_policy(policy
) != (param
->sched_priority
!= 0))
4252 * Allow unprivileged RT tasks to decrease priority:
4254 if (!capable(CAP_SYS_NICE
)) {
4255 if (is_rt_policy(policy
)) {
4256 unsigned long rlim_rtprio
;
4257 unsigned long flags
;
4259 if (!lock_task_sighand(p
, &flags
))
4261 rlim_rtprio
= p
->signal
->rlim
[RLIMIT_RTPRIO
].rlim_cur
;
4262 unlock_task_sighand(p
, &flags
);
4264 /* can't set/change the rt policy */
4265 if (policy
!= p
->policy
&& !rlim_rtprio
)
4268 /* can't increase priority */
4269 if (param
->sched_priority
> p
->rt_priority
&&
4270 param
->sched_priority
> rlim_rtprio
)
4274 /* can't change other user's priorities */
4275 if ((current
->euid
!= p
->euid
) &&
4276 (current
->euid
!= p
->uid
))
4280 retval
= security_task_setscheduler(p
, policy
, param
);
4284 * make sure no PI-waiters arrive (or leave) while we are
4285 * changing the priority of the task:
4287 spin_lock_irqsave(&p
->pi_lock
, flags
);
4289 * To be able to change p->policy safely, the apropriate
4290 * runqueue lock must be held.
4292 rq
= __task_rq_lock(p
);
4293 /* recheck policy now with rq lock held */
4294 if (unlikely(oldpolicy
!= -1 && oldpolicy
!= p
->policy
)) {
4295 policy
= oldpolicy
= -1;
4296 __task_rq_unlock(rq
);
4297 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4302 deactivate_task(p
, rq
);
4304 __setscheduler(p
, policy
, param
->sched_priority
);
4306 __activate_task(p
, rq
);
4308 * Reschedule if we are currently running on this runqueue and
4309 * our priority decreased, or if we are not currently running on
4310 * this runqueue and our priority is higher than the current's
4312 if (task_running(rq
, p
)) {
4313 if (p
->prio
> oldprio
)
4314 resched_task(rq
->curr
);
4315 } else if (TASK_PREEMPTS_CURR(p
, rq
))
4316 resched_task(rq
->curr
);
4318 __task_rq_unlock(rq
);
4319 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
4321 rt_mutex_adjust_pi(p
);
4325 EXPORT_SYMBOL_GPL(sched_setscheduler
);
4328 do_sched_setscheduler(pid_t pid
, int policy
, struct sched_param __user
*param
)
4330 struct sched_param lparam
;
4331 struct task_struct
*p
;
4334 if (!param
|| pid
< 0)
4336 if (copy_from_user(&lparam
, param
, sizeof(struct sched_param
)))
4341 p
= find_process_by_pid(pid
);
4343 retval
= sched_setscheduler(p
, policy
, &lparam
);
4350 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4351 * @pid: the pid in question.
4352 * @policy: new policy.
4353 * @param: structure containing the new RT priority.
4355 asmlinkage
long sys_sched_setscheduler(pid_t pid
, int policy
,
4356 struct sched_param __user
*param
)
4358 /* negative values for policy are not valid */
4362 return do_sched_setscheduler(pid
, policy
, param
);
4366 * sys_sched_setparam - set/change the RT priority of a thread
4367 * @pid: the pid in question.
4368 * @param: structure containing the new RT priority.
4370 asmlinkage
long sys_sched_setparam(pid_t pid
, struct sched_param __user
*param
)
4372 return do_sched_setscheduler(pid
, -1, param
);
4376 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4377 * @pid: the pid in question.
4379 asmlinkage
long sys_sched_getscheduler(pid_t pid
)
4381 struct task_struct
*p
;
4382 int retval
= -EINVAL
;
4388 read_lock(&tasklist_lock
);
4389 p
= find_process_by_pid(pid
);
4391 retval
= security_task_getscheduler(p
);
4395 read_unlock(&tasklist_lock
);
4402 * sys_sched_getscheduler - get the RT priority of a thread
4403 * @pid: the pid in question.
4404 * @param: structure containing the RT priority.
4406 asmlinkage
long sys_sched_getparam(pid_t pid
, struct sched_param __user
*param
)
4408 struct sched_param lp
;
4409 struct task_struct
*p
;
4410 int retval
= -EINVAL
;
4412 if (!param
|| pid
< 0)
4415 read_lock(&tasklist_lock
);
4416 p
= find_process_by_pid(pid
);
4421 retval
= security_task_getscheduler(p
);
4425 lp
.sched_priority
= p
->rt_priority
;
4426 read_unlock(&tasklist_lock
);
4429 * This one might sleep, we cannot do it with a spinlock held ...
4431 retval
= copy_to_user(param
, &lp
, sizeof(*param
)) ? -EFAULT
: 0;
4437 read_unlock(&tasklist_lock
);
4441 long sched_setaffinity(pid_t pid
, cpumask_t new_mask
)
4443 cpumask_t cpus_allowed
;
4444 struct task_struct
*p
;
4448 read_lock(&tasklist_lock
);
4450 p
= find_process_by_pid(pid
);
4452 read_unlock(&tasklist_lock
);
4453 unlock_cpu_hotplug();
4458 * It is not safe to call set_cpus_allowed with the
4459 * tasklist_lock held. We will bump the task_struct's
4460 * usage count and then drop tasklist_lock.
4463 read_unlock(&tasklist_lock
);
4466 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
4467 !capable(CAP_SYS_NICE
))
4470 retval
= security_task_setscheduler(p
, 0, NULL
);
4474 cpus_allowed
= cpuset_cpus_allowed(p
);
4475 cpus_and(new_mask
, new_mask
, cpus_allowed
);
4476 retval
= set_cpus_allowed(p
, new_mask
);
4480 unlock_cpu_hotplug();
4484 static int get_user_cpu_mask(unsigned long __user
*user_mask_ptr
, unsigned len
,
4485 cpumask_t
*new_mask
)
4487 if (len
< sizeof(cpumask_t
)) {
4488 memset(new_mask
, 0, sizeof(cpumask_t
));
4489 } else if (len
> sizeof(cpumask_t
)) {
4490 len
= sizeof(cpumask_t
);
4492 return copy_from_user(new_mask
, user_mask_ptr
, len
) ? -EFAULT
: 0;
4496 * sys_sched_setaffinity - set the cpu affinity of a process
4497 * @pid: pid of the process
4498 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4499 * @user_mask_ptr: user-space pointer to the new cpu mask
4501 asmlinkage
long sys_sched_setaffinity(pid_t pid
, unsigned int len
,
4502 unsigned long __user
*user_mask_ptr
)
4507 retval
= get_user_cpu_mask(user_mask_ptr
, len
, &new_mask
);
4511 return sched_setaffinity(pid
, new_mask
);
4515 * Represents all cpu's present in the system
4516 * In systems capable of hotplug, this map could dynamically grow
4517 * as new cpu's are detected in the system via any platform specific
4518 * method, such as ACPI for e.g.
4521 cpumask_t cpu_present_map __read_mostly
;
4522 EXPORT_SYMBOL(cpu_present_map
);
4525 cpumask_t cpu_online_map __read_mostly
= CPU_MASK_ALL
;
4526 EXPORT_SYMBOL(cpu_online_map
);
4528 cpumask_t cpu_possible_map __read_mostly
= CPU_MASK_ALL
;
4529 EXPORT_SYMBOL(cpu_possible_map
);
4532 long sched_getaffinity(pid_t pid
, cpumask_t
*mask
)
4534 struct task_struct
*p
;
4538 read_lock(&tasklist_lock
);
4541 p
= find_process_by_pid(pid
);
4545 retval
= security_task_getscheduler(p
);
4549 cpus_and(*mask
, p
->cpus_allowed
, cpu_online_map
);
4552 read_unlock(&tasklist_lock
);
4553 unlock_cpu_hotplug();
4561 * sys_sched_getaffinity - get the cpu affinity of a process
4562 * @pid: pid of the process
4563 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4564 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4566 asmlinkage
long sys_sched_getaffinity(pid_t pid
, unsigned int len
,
4567 unsigned long __user
*user_mask_ptr
)
4572 if (len
< sizeof(cpumask_t
))
4575 ret
= sched_getaffinity(pid
, &mask
);
4579 if (copy_to_user(user_mask_ptr
, &mask
, sizeof(cpumask_t
)))
4582 return sizeof(cpumask_t
);
4586 * sys_sched_yield - yield the current processor to other threads.
4588 * This function yields the current CPU by moving the calling thread
4589 * to the expired array. If there are no other threads running on this
4590 * CPU then this function will return.
4592 asmlinkage
long sys_sched_yield(void)
4594 struct rq
*rq
= this_rq_lock();
4595 struct prio_array
*array
= current
->array
, *target
= rq
->expired
;
4597 schedstat_inc(rq
, yld_cnt
);
4599 * We implement yielding by moving the task into the expired
4602 * (special rule: RT tasks will just roundrobin in the active
4605 if (rt_task(current
))
4606 target
= rq
->active
;
4608 if (array
->nr_active
== 1) {
4609 schedstat_inc(rq
, yld_act_empty
);
4610 if (!rq
->expired
->nr_active
)
4611 schedstat_inc(rq
, yld_both_empty
);
4612 } else if (!rq
->expired
->nr_active
)
4613 schedstat_inc(rq
, yld_exp_empty
);
4615 if (array
!= target
) {
4616 dequeue_task(current
, array
);
4617 enqueue_task(current
, target
);
4620 * requeue_task is cheaper so perform that if possible.
4622 requeue_task(current
, array
);
4625 * Since we are going to call schedule() anyway, there's
4626 * no need to preempt or enable interrupts:
4628 __release(rq
->lock
);
4629 spin_release(&rq
->lock
.dep_map
, 1, _THIS_IP_
);
4630 _raw_spin_unlock(&rq
->lock
);
4631 preempt_enable_no_resched();
4638 static void __cond_resched(void)
4640 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
4641 __might_sleep(__FILE__
, __LINE__
);
4644 * The BKS might be reacquired before we have dropped
4645 * PREEMPT_ACTIVE, which could trigger a second
4646 * cond_resched() call.
4649 add_preempt_count(PREEMPT_ACTIVE
);
4651 sub_preempt_count(PREEMPT_ACTIVE
);
4652 } while (need_resched());
4655 int __sched
cond_resched(void)
4657 if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE
) &&
4658 system_state
== SYSTEM_RUNNING
) {
4664 EXPORT_SYMBOL(cond_resched
);
4667 * cond_resched_lock() - if a reschedule is pending, drop the given lock,
4668 * call schedule, and on return reacquire the lock.
4670 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4671 * operations here to prevent schedule() from being called twice (once via
4672 * spin_unlock(), once by hand).
4674 int cond_resched_lock(spinlock_t
*lock
)
4678 if (need_lockbreak(lock
)) {
4684 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4685 spin_release(&lock
->dep_map
, 1, _THIS_IP_
);
4686 _raw_spin_unlock(lock
);
4687 preempt_enable_no_resched();
4694 EXPORT_SYMBOL(cond_resched_lock
);
4696 int __sched
cond_resched_softirq(void)
4698 BUG_ON(!in_softirq());
4700 if (need_resched() && system_state
== SYSTEM_RUNNING
) {
4701 raw_local_irq_disable();
4703 raw_local_irq_enable();
4710 EXPORT_SYMBOL(cond_resched_softirq
);
4713 * yield - yield the current processor to other threads.
4715 * This is a shortcut for kernel-space yielding - it marks the
4716 * thread runnable and calls sys_sched_yield().
4718 void __sched
yield(void)
4720 set_current_state(TASK_RUNNING
);
4723 EXPORT_SYMBOL(yield
);
4726 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4727 * that process accounting knows that this is a task in IO wait state.
4729 * But don't do that if it is a deliberate, throttling IO wait (this task
4730 * has set its backing_dev_info: the queue against which it should throttle)
4732 void __sched
io_schedule(void)
4734 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4736 delayacct_blkio_start();
4737 atomic_inc(&rq
->nr_iowait
);
4739 atomic_dec(&rq
->nr_iowait
);
4740 delayacct_blkio_end();
4742 EXPORT_SYMBOL(io_schedule
);
4744 long __sched
io_schedule_timeout(long timeout
)
4746 struct rq
*rq
= &__raw_get_cpu_var(runqueues
);
4749 delayacct_blkio_start();
4750 atomic_inc(&rq
->nr_iowait
);
4751 ret
= schedule_timeout(timeout
);
4752 atomic_dec(&rq
->nr_iowait
);
4753 delayacct_blkio_end();
4758 * sys_sched_get_priority_max - return maximum RT priority.
4759 * @policy: scheduling class.
4761 * this syscall returns the maximum rt_priority that can be used
4762 * by a given scheduling class.
4764 asmlinkage
long sys_sched_get_priority_max(int policy
)
4771 ret
= MAX_USER_RT_PRIO
-1;
4782 * sys_sched_get_priority_min - return minimum RT priority.
4783 * @policy: scheduling class.
4785 * this syscall returns the minimum rt_priority that can be used
4786 * by a given scheduling class.
4788 asmlinkage
long sys_sched_get_priority_min(int policy
)
4805 * sys_sched_rr_get_interval - return the default timeslice of a process.
4806 * @pid: pid of the process.
4807 * @interval: userspace pointer to the timeslice value.
4809 * this syscall writes the default timeslice value of a given process
4810 * into the user-space timespec buffer. A value of '0' means infinity.
4813 long sys_sched_rr_get_interval(pid_t pid
, struct timespec __user
*interval
)
4815 struct task_struct
*p
;
4816 int retval
= -EINVAL
;
4823 read_lock(&tasklist_lock
);
4824 p
= find_process_by_pid(pid
);
4828 retval
= security_task_getscheduler(p
);
4832 jiffies_to_timespec(p
->policy
== SCHED_FIFO
?
4833 0 : task_timeslice(p
), &t
);
4834 read_unlock(&tasklist_lock
);
4835 retval
= copy_to_user(interval
, &t
, sizeof(t
)) ? -EFAULT
: 0;
4839 read_unlock(&tasklist_lock
);
4843 static inline struct task_struct
*eldest_child(struct task_struct
*p
)
4845 if (list_empty(&p
->children
))
4847 return list_entry(p
->children
.next
,struct task_struct
,sibling
);
4850 static inline struct task_struct
*older_sibling(struct task_struct
*p
)
4852 if (p
->sibling
.prev
==&p
->parent
->children
)
4854 return list_entry(p
->sibling
.prev
,struct task_struct
,sibling
);
4857 static inline struct task_struct
*younger_sibling(struct task_struct
*p
)
4859 if (p
->sibling
.next
==&p
->parent
->children
)
4861 return list_entry(p
->sibling
.next
,struct task_struct
,sibling
);
4864 static const char stat_nam
[] = "RSDTtZX";
4866 static void show_task(struct task_struct
*p
)
4868 struct task_struct
*relative
;
4869 unsigned long free
= 0;
4872 state
= p
->state
? __ffs(p
->state
) + 1 : 0;
4873 printk("%-13.13s %c", p
->comm
,
4874 state
< sizeof(stat_nam
) - 1 ? stat_nam
[state
] : '?');
4875 #if (BITS_PER_LONG == 32)
4876 if (state
== TASK_RUNNING
)
4877 printk(" running ");
4879 printk(" %08lX ", thread_saved_pc(p
));
4881 if (state
== TASK_RUNNING
)
4882 printk(" running task ");
4884 printk(" %016lx ", thread_saved_pc(p
));
4886 #ifdef CONFIG_DEBUG_STACK_USAGE
4888 unsigned long *n
= end_of_stack(p
);
4891 free
= (unsigned long)n
- (unsigned long)end_of_stack(p
);
4894 printk("%5lu %5d %6d ", free
, p
->pid
, p
->parent
->pid
);
4895 if ((relative
= eldest_child(p
)))
4896 printk("%5d ", relative
->pid
);
4899 if ((relative
= younger_sibling(p
)))
4900 printk("%7d", relative
->pid
);
4903 if ((relative
= older_sibling(p
)))
4904 printk(" %5d", relative
->pid
);
4908 printk(" (L-TLB)\n");
4910 printk(" (NOTLB)\n");
4912 if (state
!= TASK_RUNNING
)
4913 show_stack(p
, NULL
);
4916 void show_state_filter(unsigned long state_filter
)
4918 struct task_struct
*g
, *p
;
4920 #if (BITS_PER_LONG == 32)
4923 printk(" task PC stack pid father child younger older\n");
4927 printk(" task PC stack pid father child younger older\n");
4929 read_lock(&tasklist_lock
);
4930 do_each_thread(g
, p
) {
4932 * reset the NMI-timeout, listing all files on a slow
4933 * console might take alot of time:
4935 touch_nmi_watchdog();
4936 if (p
->state
& state_filter
)
4938 } while_each_thread(g
, p
);
4940 read_unlock(&tasklist_lock
);
4942 * Only show locks if all tasks are dumped:
4944 if (state_filter
== -1)
4945 debug_show_all_locks();
4949 * init_idle - set up an idle thread for a given CPU
4950 * @idle: task in question
4951 * @cpu: cpu the idle task belongs to
4953 * NOTE: this function does not set the idle thread's NEED_RESCHED
4954 * flag, to make booting more robust.
4956 void __cpuinit
init_idle(struct task_struct
*idle
, int cpu
)
4958 struct rq
*rq
= cpu_rq(cpu
);
4959 unsigned long flags
;
4961 idle
->timestamp
= sched_clock();
4962 idle
->sleep_avg
= 0;
4964 idle
->prio
= idle
->normal_prio
= MAX_PRIO
;
4965 idle
->state
= TASK_RUNNING
;
4966 idle
->cpus_allowed
= cpumask_of_cpu(cpu
);
4967 set_task_cpu(idle
, cpu
);
4969 spin_lock_irqsave(&rq
->lock
, flags
);
4970 rq
->curr
= rq
->idle
= idle
;
4971 #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4974 spin_unlock_irqrestore(&rq
->lock
, flags
);
4976 /* Set the preempt count _outside_ the spinlocks! */
4977 #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL)
4978 task_thread_info(idle
)->preempt_count
= (idle
->lock_depth
>= 0);
4980 task_thread_info(idle
)->preempt_count
= 0;
4985 * In a system that switches off the HZ timer nohz_cpu_mask
4986 * indicates which cpus entered this state. This is used
4987 * in the rcu update to wait only for active cpus. For system
4988 * which do not switch off the HZ timer nohz_cpu_mask should
4989 * always be CPU_MASK_NONE.
4991 cpumask_t nohz_cpu_mask
= CPU_MASK_NONE
;
4995 * This is how migration works:
4997 * 1) we queue a struct migration_req structure in the source CPU's
4998 * runqueue and wake up that CPU's migration thread.
4999 * 2) we down() the locked semaphore => thread blocks.
5000 * 3) migration thread wakes up (implicitly it forces the migrated
5001 * thread off the CPU)
5002 * 4) it gets the migration request and checks whether the migrated
5003 * task is still in the wrong runqueue.
5004 * 5) if it's in the wrong runqueue then the migration thread removes
5005 * it and puts it into the right queue.
5006 * 6) migration thread up()s the semaphore.
5007 * 7) we wake up and the migration is done.
5011 * Change a given task's CPU affinity. Migrate the thread to a
5012 * proper CPU and schedule it away if the CPU it's executing on
5013 * is removed from the allowed bitmask.
5015 * NOTE: the caller must have a valid reference to the task, the
5016 * task must not exit() & deallocate itself prematurely. The
5017 * call is not atomic; no spinlocks may be held.
5019 int set_cpus_allowed(struct task_struct
*p
, cpumask_t new_mask
)
5021 struct migration_req req
;
5022 unsigned long flags
;
5026 rq
= task_rq_lock(p
, &flags
);
5027 if (!cpus_intersects(new_mask
, cpu_online_map
)) {
5032 p
->cpus_allowed
= new_mask
;
5033 /* Can the task run on the task's current CPU? If so, we're done */
5034 if (cpu_isset(task_cpu(p
), new_mask
))
5037 if (migrate_task(p
, any_online_cpu(new_mask
), &req
)) {
5038 /* Need help from migration thread: drop lock and wait. */
5039 task_rq_unlock(rq
, &flags
);
5040 wake_up_process(rq
->migration_thread
);
5041 wait_for_completion(&req
.done
);
5042 tlb_migrate_finish(p
->mm
);
5046 task_rq_unlock(rq
, &flags
);
5050 EXPORT_SYMBOL_GPL(set_cpus_allowed
);
5053 * Move (not current) task off this cpu, onto dest cpu. We're doing
5054 * this because either it can't run here any more (set_cpus_allowed()
5055 * away from this CPU, or CPU going down), or because we're
5056 * attempting to rebalance this task on exec (sched_exec).
5058 * So we race with normal scheduler movements, but that's OK, as long
5059 * as the task is no longer on this CPU.
5061 * Returns non-zero if task was successfully migrated.
5063 static int __migrate_task(struct task_struct
*p
, int src_cpu
, int dest_cpu
)
5065 struct rq
*rq_dest
, *rq_src
;
5068 if (unlikely(cpu_is_offline(dest_cpu
)))
5071 rq_src
= cpu_rq(src_cpu
);
5072 rq_dest
= cpu_rq(dest_cpu
);
5074 double_rq_lock(rq_src
, rq_dest
);
5075 /* Already moved. */
5076 if (task_cpu(p
) != src_cpu
)
5078 /* Affinity changed (again). */
5079 if (!cpu_isset(dest_cpu
, p
->cpus_allowed
))
5082 set_task_cpu(p
, dest_cpu
);
5085 * Sync timestamp with rq_dest's before activating.
5086 * The same thing could be achieved by doing this step
5087 * afterwards, and pretending it was a local activate.
5088 * This way is cleaner and logically correct.
5090 p
->timestamp
= p
->timestamp
- rq_src
->most_recent_timestamp
5091 + rq_dest
->most_recent_timestamp
;
5092 deactivate_task(p
, rq_src
);
5093 __activate_task(p
, rq_dest
);
5094 if (TASK_PREEMPTS_CURR(p
, rq_dest
))
5095 resched_task(rq_dest
->curr
);
5099 double_rq_unlock(rq_src
, rq_dest
);
5104 * migration_thread - this is a highprio system thread that performs
5105 * thread migration by bumping thread off CPU then 'pushing' onto
5108 static int migration_thread(void *data
)
5110 int cpu
= (long)data
;
5114 BUG_ON(rq
->migration_thread
!= current
);
5116 set_current_state(TASK_INTERRUPTIBLE
);
5117 while (!kthread_should_stop()) {
5118 struct migration_req
*req
;
5119 struct list_head
*head
;
5123 spin_lock_irq(&rq
->lock
);
5125 if (cpu_is_offline(cpu
)) {
5126 spin_unlock_irq(&rq
->lock
);
5130 if (rq
->active_balance
) {
5131 active_load_balance(rq
, cpu
);
5132 rq
->active_balance
= 0;
5135 head
= &rq
->migration_queue
;
5137 if (list_empty(head
)) {
5138 spin_unlock_irq(&rq
->lock
);
5140 set_current_state(TASK_INTERRUPTIBLE
);
5143 req
= list_entry(head
->next
, struct migration_req
, list
);
5144 list_del_init(head
->next
);
5146 spin_unlock(&rq
->lock
);
5147 __migrate_task(req
->task
, cpu
, req
->dest_cpu
);
5150 complete(&req
->done
);
5152 __set_current_state(TASK_RUNNING
);
5156 /* Wait for kthread_stop */
5157 set_current_state(TASK_INTERRUPTIBLE
);
5158 while (!kthread_should_stop()) {
5160 set_current_state(TASK_INTERRUPTIBLE
);
5162 __set_current_state(TASK_RUNNING
);
5166 #ifdef CONFIG_HOTPLUG_CPU
5168 * Figure out where task on dead CPU should go, use force if neccessary.
5169 * NOTE: interrupts should be disabled by the caller
5171 static void move_task_off_dead_cpu(int dead_cpu
, struct task_struct
*p
)
5173 unsigned long flags
;
5180 mask
= node_to_cpumask(cpu_to_node(dead_cpu
));
5181 cpus_and(mask
, mask
, p
->cpus_allowed
);
5182 dest_cpu
= any_online_cpu(mask
);
5184 /* On any allowed CPU? */
5185 if (dest_cpu
== NR_CPUS
)
5186 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5188 /* No more Mr. Nice Guy. */
5189 if (dest_cpu
== NR_CPUS
) {
5190 rq
= task_rq_lock(p
, &flags
);
5191 cpus_setall(p
->cpus_allowed
);
5192 dest_cpu
= any_online_cpu(p
->cpus_allowed
);
5193 task_rq_unlock(rq
, &flags
);
5196 * Don't tell them about moving exiting tasks or
5197 * kernel threads (both mm NULL), since they never
5200 if (p
->mm
&& printk_ratelimit())
5201 printk(KERN_INFO
"process %d (%s) no "
5202 "longer affine to cpu%d\n",
5203 p
->pid
, p
->comm
, dead_cpu
);
5205 if (!__migrate_task(p
, dead_cpu
, dest_cpu
))
5210 * While a dead CPU has no uninterruptible tasks queued at this point,
5211 * it might still have a nonzero ->nr_uninterruptible counter, because
5212 * for performance reasons the counter is not stricly tracking tasks to
5213 * their home CPUs. So we just add the counter to another CPU's counter,
5214 * to keep the global sum constant after CPU-down:
5216 static void migrate_nr_uninterruptible(struct rq
*rq_src
)
5218 struct rq
*rq_dest
= cpu_rq(any_online_cpu(CPU_MASK_ALL
));
5219 unsigned long flags
;
5221 local_irq_save(flags
);
5222 double_rq_lock(rq_src
, rq_dest
);
5223 rq_dest
->nr_uninterruptible
+= rq_src
->nr_uninterruptible
;
5224 rq_src
->nr_uninterruptible
= 0;
5225 double_rq_unlock(rq_src
, rq_dest
);
5226 local_irq_restore(flags
);
5229 /* Run through task list and migrate tasks from the dead cpu. */
5230 static void migrate_live_tasks(int src_cpu
)
5232 struct task_struct
*p
, *t
;
5234 write_lock_irq(&tasklist_lock
);
5236 do_each_thread(t
, p
) {
5240 if (task_cpu(p
) == src_cpu
)
5241 move_task_off_dead_cpu(src_cpu
, p
);
5242 } while_each_thread(t
, p
);
5244 write_unlock_irq(&tasklist_lock
);
5247 /* Schedules idle task to be the next runnable task on current CPU.
5248 * It does so by boosting its priority to highest possible and adding it to
5249 * the _front_ of the runqueue. Used by CPU offline code.
5251 void sched_idle_next(void)
5253 int this_cpu
= smp_processor_id();
5254 struct rq
*rq
= cpu_rq(this_cpu
);
5255 struct task_struct
*p
= rq
->idle
;
5256 unsigned long flags
;
5258 /* cpu has to be offline */
5259 BUG_ON(cpu_online(this_cpu
));
5262 * Strictly not necessary since rest of the CPUs are stopped by now
5263 * and interrupts disabled on the current cpu.
5265 spin_lock_irqsave(&rq
->lock
, flags
);
5267 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5269 /* Add idle task to the _front_ of its priority queue: */
5270 __activate_idle_task(p
, rq
);
5272 spin_unlock_irqrestore(&rq
->lock
, flags
);
5276 * Ensures that the idle task is using init_mm right before its cpu goes
5279 void idle_task_exit(void)
5281 struct mm_struct
*mm
= current
->active_mm
;
5283 BUG_ON(cpu_online(smp_processor_id()));
5286 switch_mm(mm
, &init_mm
, current
);
5290 /* called under rq->lock with disabled interrupts */
5291 static void migrate_dead(unsigned int dead_cpu
, struct task_struct
*p
)
5293 struct rq
*rq
= cpu_rq(dead_cpu
);
5295 /* Must be exiting, otherwise would be on tasklist. */
5296 BUG_ON(p
->exit_state
!= EXIT_ZOMBIE
&& p
->exit_state
!= EXIT_DEAD
);
5298 /* Cannot have done final schedule yet: would have vanished. */
5299 BUG_ON(p
->state
== TASK_DEAD
);
5304 * Drop lock around migration; if someone else moves it,
5305 * that's OK. No task can be added to this CPU, so iteration is
5307 * NOTE: interrupts should be left disabled --dev@
5309 spin_unlock(&rq
->lock
);
5310 move_task_off_dead_cpu(dead_cpu
, p
);
5311 spin_lock(&rq
->lock
);
5316 /* release_task() removes task from tasklist, so we won't find dead tasks. */
5317 static void migrate_dead_tasks(unsigned int dead_cpu
)
5319 struct rq
*rq
= cpu_rq(dead_cpu
);
5320 unsigned int arr
, i
;
5322 for (arr
= 0; arr
< 2; arr
++) {
5323 for (i
= 0; i
< MAX_PRIO
; i
++) {
5324 struct list_head
*list
= &rq
->arrays
[arr
].queue
[i
];
5326 while (!list_empty(list
))
5327 migrate_dead(dead_cpu
, list_entry(list
->next
,
5328 struct task_struct
, run_list
));
5332 #endif /* CONFIG_HOTPLUG_CPU */
5335 * migration_call - callback that gets triggered when a CPU is added.
5336 * Here we can start up the necessary migration thread for the new CPU.
5338 static int __cpuinit
5339 migration_call(struct notifier_block
*nfb
, unsigned long action
, void *hcpu
)
5341 struct task_struct
*p
;
5342 int cpu
= (long)hcpu
;
5343 unsigned long flags
;
5347 case CPU_UP_PREPARE
:
5348 p
= kthread_create(migration_thread
, hcpu
, "migration/%d",cpu
);
5351 p
->flags
|= PF_NOFREEZE
;
5352 kthread_bind(p
, cpu
);
5353 /* Must be high prio: stop_machine expects to yield to it. */
5354 rq
= task_rq_lock(p
, &flags
);
5355 __setscheduler(p
, SCHED_FIFO
, MAX_RT_PRIO
-1);
5356 task_rq_unlock(rq
, &flags
);
5357 cpu_rq(cpu
)->migration_thread
= p
;
5361 /* Strictly unneccessary, as first user will wake it. */
5362 wake_up_process(cpu_rq(cpu
)->migration_thread
);
5365 #ifdef CONFIG_HOTPLUG_CPU
5366 case CPU_UP_CANCELED
:
5367 if (!cpu_rq(cpu
)->migration_thread
)
5369 /* Unbind it from offline cpu so it can run. Fall thru. */
5370 kthread_bind(cpu_rq(cpu
)->migration_thread
,
5371 any_online_cpu(cpu_online_map
));
5372 kthread_stop(cpu_rq(cpu
)->migration_thread
);
5373 cpu_rq(cpu
)->migration_thread
= NULL
;
5377 migrate_live_tasks(cpu
);
5379 kthread_stop(rq
->migration_thread
);
5380 rq
->migration_thread
= NULL
;
5381 /* Idle task back to normal (off runqueue, low prio) */
5382 rq
= task_rq_lock(rq
->idle
, &flags
);
5383 deactivate_task(rq
->idle
, rq
);
5384 rq
->idle
->static_prio
= MAX_PRIO
;
5385 __setscheduler(rq
->idle
, SCHED_NORMAL
, 0);
5386 migrate_dead_tasks(cpu
);
5387 task_rq_unlock(rq
, &flags
);
5388 migrate_nr_uninterruptible(rq
);
5389 BUG_ON(rq
->nr_running
!= 0);
5391 /* No need to migrate the tasks: it was best-effort if
5392 * they didn't do lock_cpu_hotplug(). Just wake up
5393 * the requestors. */
5394 spin_lock_irq(&rq
->lock
);
5395 while (!list_empty(&rq
->migration_queue
)) {
5396 struct migration_req
*req
;
5398 req
= list_entry(rq
->migration_queue
.next
,
5399 struct migration_req
, list
);
5400 list_del_init(&req
->list
);
5401 complete(&req
->done
);
5403 spin_unlock_irq(&rq
->lock
);
5410 /* Register at highest priority so that task migration (migrate_all_tasks)
5411 * happens before everything else.
5413 static struct notifier_block __cpuinitdata migration_notifier
= {
5414 .notifier_call
= migration_call
,
5418 int __init
migration_init(void)
5420 void *cpu
= (void *)(long)smp_processor_id();
5423 /* Start one for the boot CPU: */
5424 err
= migration_call(&migration_notifier
, CPU_UP_PREPARE
, cpu
);
5425 BUG_ON(err
== NOTIFY_BAD
);
5426 migration_call(&migration_notifier
, CPU_ONLINE
, cpu
);
5427 register_cpu_notifier(&migration_notifier
);
5434 #undef SCHED_DOMAIN_DEBUG
5435 #ifdef SCHED_DOMAIN_DEBUG
5436 static void sched_domain_debug(struct sched_domain
*sd
, int cpu
)
5441 printk(KERN_DEBUG
"CPU%d attaching NULL sched-domain.\n", cpu
);
5445 printk(KERN_DEBUG
"CPU%d attaching sched-domain:\n", cpu
);
5450 struct sched_group
*group
= sd
->groups
;
5451 cpumask_t groupmask
;
5453 cpumask_scnprintf(str
, NR_CPUS
, sd
->span
);
5454 cpus_clear(groupmask
);
5457 for (i
= 0; i
< level
+ 1; i
++)
5459 printk("domain %d: ", level
);
5461 if (!(sd
->flags
& SD_LOAD_BALANCE
)) {
5462 printk("does not load-balance\n");
5464 printk(KERN_ERR
"ERROR: !SD_LOAD_BALANCE domain"
5469 printk("span %s\n", str
);
5471 if (!cpu_isset(cpu
, sd
->span
))
5472 printk(KERN_ERR
"ERROR: domain->span does not contain "
5474 if (!cpu_isset(cpu
, group
->cpumask
))
5475 printk(KERN_ERR
"ERROR: domain->groups does not contain"
5479 for (i
= 0; i
< level
+ 2; i
++)
5485 printk(KERN_ERR
"ERROR: group is NULL\n");
5489 if (!group
->cpu_power
) {
5491 printk(KERN_ERR
"ERROR: domain->cpu_power not "
5495 if (!cpus_weight(group
->cpumask
)) {
5497 printk(KERN_ERR
"ERROR: empty group\n");
5500 if (cpus_intersects(groupmask
, group
->cpumask
)) {
5502 printk(KERN_ERR
"ERROR: repeated CPUs\n");
5505 cpus_or(groupmask
, groupmask
, group
->cpumask
);
5507 cpumask_scnprintf(str
, NR_CPUS
, group
->cpumask
);
5510 group
= group
->next
;
5511 } while (group
!= sd
->groups
);
5514 if (!cpus_equal(sd
->span
, groupmask
))
5515 printk(KERN_ERR
"ERROR: groups don't span "
5523 if (!cpus_subset(groupmask
, sd
->span
))
5524 printk(KERN_ERR
"ERROR: parent span is not a superset "
5525 "of domain->span\n");
5530 # define sched_domain_debug(sd, cpu) do { } while (0)
5533 static int sd_degenerate(struct sched_domain
*sd
)
5535 if (cpus_weight(sd
->span
) == 1)
5538 /* Following flags need at least 2 groups */
5539 if (sd
->flags
& (SD_LOAD_BALANCE
|
5540 SD_BALANCE_NEWIDLE
|
5544 SD_SHARE_PKG_RESOURCES
)) {
5545 if (sd
->groups
!= sd
->groups
->next
)
5549 /* Following flags don't use groups */
5550 if (sd
->flags
& (SD_WAKE_IDLE
|
5559 sd_parent_degenerate(struct sched_domain
*sd
, struct sched_domain
*parent
)
5561 unsigned long cflags
= sd
->flags
, pflags
= parent
->flags
;
5563 if (sd_degenerate(parent
))
5566 if (!cpus_equal(sd
->span
, parent
->span
))
5569 /* Does parent contain flags not in child? */
5570 /* WAKE_BALANCE is a subset of WAKE_AFFINE */
5571 if (cflags
& SD_WAKE_AFFINE
)
5572 pflags
&= ~SD_WAKE_BALANCE
;
5573 /* Flags needing groups don't count if only 1 group in parent */
5574 if (parent
->groups
== parent
->groups
->next
) {
5575 pflags
&= ~(SD_LOAD_BALANCE
|
5576 SD_BALANCE_NEWIDLE
|
5580 SD_SHARE_PKG_RESOURCES
);
5582 if (~cflags
& pflags
)
5589 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5590 * hold the hotplug lock.
5592 static void cpu_attach_domain(struct sched_domain
*sd
, int cpu
)
5594 struct rq
*rq
= cpu_rq(cpu
);
5595 struct sched_domain
*tmp
;
5597 /* Remove the sched domains which do not contribute to scheduling. */
5598 for (tmp
= sd
; tmp
; tmp
= tmp
->parent
) {
5599 struct sched_domain
*parent
= tmp
->parent
;
5602 if (sd_parent_degenerate(tmp
, parent
)) {
5603 tmp
->parent
= parent
->parent
;
5605 parent
->parent
->child
= tmp
;
5609 if (sd
&& sd_degenerate(sd
)) {
5615 sched_domain_debug(sd
, cpu
);
5617 rcu_assign_pointer(rq
->sd
, sd
);
5620 /* cpus with isolated domains */
5621 static cpumask_t cpu_isolated_map
= CPU_MASK_NONE
;
5623 /* Setup the mask of cpus configured for isolated domains */
5624 static int __init
isolated_cpu_setup(char *str
)
5626 int ints
[NR_CPUS
], i
;
5628 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5629 cpus_clear(cpu_isolated_map
);
5630 for (i
= 1; i
<= ints
[0]; i
++)
5631 if (ints
[i
] < NR_CPUS
)
5632 cpu_set(ints
[i
], cpu_isolated_map
);
5636 __setup ("isolcpus=", isolated_cpu_setup
);
5639 * init_sched_build_groups takes the cpumask we wish to span, and a pointer
5640 * to a function which identifies what group(along with sched group) a CPU
5641 * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS
5642 * (due to the fact that we keep track of groups covered with a cpumask_t).
5644 * init_sched_build_groups will build a circular linked list of the groups
5645 * covered by the given span, and will set each group's ->cpumask correctly,
5646 * and ->cpu_power to 0.
5649 init_sched_build_groups(cpumask_t span
, const cpumask_t
*cpu_map
,
5650 int (*group_fn
)(int cpu
, const cpumask_t
*cpu_map
,
5651 struct sched_group
**sg
))
5653 struct sched_group
*first
= NULL
, *last
= NULL
;
5654 cpumask_t covered
= CPU_MASK_NONE
;
5657 for_each_cpu_mask(i
, span
) {
5658 struct sched_group
*sg
;
5659 int group
= group_fn(i
, cpu_map
, &sg
);
5662 if (cpu_isset(i
, covered
))
5665 sg
->cpumask
= CPU_MASK_NONE
;
5668 for_each_cpu_mask(j
, span
) {
5669 if (group_fn(j
, cpu_map
, NULL
) != group
)
5672 cpu_set(j
, covered
);
5673 cpu_set(j
, sg
->cpumask
);
5684 #define SD_NODES_PER_DOMAIN 16
5687 * Self-tuning task migration cost measurement between source and target CPUs.
5689 * This is done by measuring the cost of manipulating buffers of varying
5690 * sizes. For a given buffer-size here are the steps that are taken:
5692 * 1) the source CPU reads+dirties a shared buffer
5693 * 2) the target CPU reads+dirties the same shared buffer
5695 * We measure how long they take, in the following 4 scenarios:
5697 * - source: CPU1, target: CPU2 | cost1
5698 * - source: CPU2, target: CPU1 | cost2
5699 * - source: CPU1, target: CPU1 | cost3
5700 * - source: CPU2, target: CPU2 | cost4
5702 * We then calculate the cost3+cost4-cost1-cost2 difference - this is
5703 * the cost of migration.
5705 * We then start off from a small buffer-size and iterate up to larger
5706 * buffer sizes, in 5% steps - measuring each buffer-size separately, and
5707 * doing a maximum search for the cost. (The maximum cost for a migration
5708 * normally occurs when the working set size is around the effective cache
5711 #define SEARCH_SCOPE 2
5712 #define MIN_CACHE_SIZE (64*1024U)
5713 #define DEFAULT_CACHE_SIZE (5*1024*1024U)
5714 #define ITERATIONS 1
5715 #define SIZE_THRESH 130
5716 #define COST_THRESH 130
5719 * The migration cost is a function of 'domain distance'. Domain
5720 * distance is the number of steps a CPU has to iterate down its
5721 * domain tree to share a domain with the other CPU. The farther
5722 * two CPUs are from each other, the larger the distance gets.
5724 * Note that we use the distance only to cache measurement results,
5725 * the distance value is not used numerically otherwise. When two
5726 * CPUs have the same distance it is assumed that the migration
5727 * cost is the same. (this is a simplification but quite practical)
5729 #define MAX_DOMAIN_DISTANCE 32
5731 static unsigned long long migration_cost
[MAX_DOMAIN_DISTANCE
] =
5732 { [ 0 ... MAX_DOMAIN_DISTANCE
-1 ] =
5734 * Architectures may override the migration cost and thus avoid
5735 * boot-time calibration. Unit is nanoseconds. Mostly useful for
5736 * virtualized hardware:
5738 #ifdef CONFIG_DEFAULT_MIGRATION_COST
5739 CONFIG_DEFAULT_MIGRATION_COST
5746 * Allow override of migration cost - in units of microseconds.
5747 * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost
5748 * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs:
5750 static int __init
migration_cost_setup(char *str
)
5752 int ints
[MAX_DOMAIN_DISTANCE
+1], i
;
5754 str
= get_options(str
, ARRAY_SIZE(ints
), ints
);
5756 printk("#ints: %d\n", ints
[0]);
5757 for (i
= 1; i
<= ints
[0]; i
++) {
5758 migration_cost
[i
-1] = (unsigned long long)ints
[i
]*1000;
5759 printk("migration_cost[%d]: %Ld\n", i
-1, migration_cost
[i
-1]);
5764 __setup ("migration_cost=", migration_cost_setup
);
5767 * Global multiplier (divisor) for migration-cutoff values,
5768 * in percentiles. E.g. use a value of 150 to get 1.5 times
5769 * longer cache-hot cutoff times.
5771 * (We scale it from 100 to 128 to long long handling easier.)
5774 #define MIGRATION_FACTOR_SCALE 128
5776 static unsigned int migration_factor
= MIGRATION_FACTOR_SCALE
;
5778 static int __init
setup_migration_factor(char *str
)
5780 get_option(&str
, &migration_factor
);
5781 migration_factor
= migration_factor
* MIGRATION_FACTOR_SCALE
/ 100;
5785 __setup("migration_factor=", setup_migration_factor
);
5788 * Estimated distance of two CPUs, measured via the number of domains
5789 * we have to pass for the two CPUs to be in the same span:
5791 static unsigned long domain_distance(int cpu1
, int cpu2
)
5793 unsigned long distance
= 0;
5794 struct sched_domain
*sd
;
5796 for_each_domain(cpu1
, sd
) {
5797 WARN_ON(!cpu_isset(cpu1
, sd
->span
));
5798 if (cpu_isset(cpu2
, sd
->span
))
5802 if (distance
>= MAX_DOMAIN_DISTANCE
) {
5804 distance
= MAX_DOMAIN_DISTANCE
-1;
5810 static unsigned int migration_debug
;
5812 static int __init
setup_migration_debug(char *str
)
5814 get_option(&str
, &migration_debug
);
5818 __setup("migration_debug=", setup_migration_debug
);
5821 * Maximum cache-size that the scheduler should try to measure.
5822 * Architectures with larger caches should tune this up during
5823 * bootup. Gets used in the domain-setup code (i.e. during SMP
5826 unsigned int max_cache_size
;
5828 static int __init
setup_max_cache_size(char *str
)
5830 get_option(&str
, &max_cache_size
);
5834 __setup("max_cache_size=", setup_max_cache_size
);
5837 * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This
5838 * is the operation that is timed, so we try to generate unpredictable
5839 * cachemisses that still end up filling the L2 cache:
5841 static void touch_cache(void *__cache
, unsigned long __size
)
5843 unsigned long size
= __size
/ sizeof(long);
5844 unsigned long chunk1
= size
/ 3;
5845 unsigned long chunk2
= 2 * size
/ 3;
5846 unsigned long *cache
= __cache
;
5849 for (i
= 0; i
< size
/6; i
+= 8) {
5852 case 1: cache
[size
-1-i
]++;
5853 case 2: cache
[chunk1
-i
]++;
5854 case 3: cache
[chunk1
+i
]++;
5855 case 4: cache
[chunk2
-i
]++;
5856 case 5: cache
[chunk2
+i
]++;
5862 * Measure the cache-cost of one task migration. Returns in units of nsec.
5864 static unsigned long long
5865 measure_one(void *cache
, unsigned long size
, int source
, int target
)
5867 cpumask_t mask
, saved_mask
;
5868 unsigned long long t0
, t1
, t2
, t3
, cost
;
5870 saved_mask
= current
->cpus_allowed
;
5873 * Flush source caches to RAM and invalidate them:
5878 * Migrate to the source CPU:
5880 mask
= cpumask_of_cpu(source
);
5881 set_cpus_allowed(current
, mask
);
5882 WARN_ON(smp_processor_id() != source
);
5885 * Dirty the working set:
5888 touch_cache(cache
, size
);
5892 * Migrate to the target CPU, dirty the L2 cache and access
5893 * the shared buffer. (which represents the working set
5894 * of a migrated task.)
5896 mask
= cpumask_of_cpu(target
);
5897 set_cpus_allowed(current
, mask
);
5898 WARN_ON(smp_processor_id() != target
);
5901 touch_cache(cache
, size
);
5904 cost
= t1
-t0
+ t3
-t2
;
5906 if (migration_debug
>= 2)
5907 printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n",
5908 source
, target
, t1
-t0
, t1
-t0
, t3
-t2
, cost
);
5910 * Flush target caches to RAM and invalidate them:
5914 set_cpus_allowed(current
, saved_mask
);
5920 * Measure a series of task migrations and return the average
5921 * result. Since this code runs early during bootup the system
5922 * is 'undisturbed' and the average latency makes sense.
5924 * The algorithm in essence auto-detects the relevant cache-size,
5925 * so it will properly detect different cachesizes for different
5926 * cache-hierarchies, depending on how the CPUs are connected.
5928 * Architectures can prime the upper limit of the search range via
5929 * max_cache_size, otherwise the search range defaults to 20MB...64K.
5931 static unsigned long long
5932 measure_cost(int cpu1
, int cpu2
, void *cache
, unsigned int size
)
5934 unsigned long long cost1
, cost2
;
5938 * Measure the migration cost of 'size' bytes, over an
5939 * average of 10 runs:
5941 * (We perturb the cache size by a small (0..4k)
5942 * value to compensate size/alignment related artifacts.
5943 * We also subtract the cost of the operation done on
5949 * dry run, to make sure we start off cache-cold on cpu1,
5950 * and to get any vmalloc pagefaults in advance:
5952 measure_one(cache
, size
, cpu1
, cpu2
);
5953 for (i
= 0; i
< ITERATIONS
; i
++)
5954 cost1
+= measure_one(cache
, size
- i
* 1024, cpu1
, cpu2
);
5956 measure_one(cache
, size
, cpu2
, cpu1
);
5957 for (i
= 0; i
< ITERATIONS
; i
++)
5958 cost1
+= measure_one(cache
, size
- i
* 1024, cpu2
, cpu1
);
5961 * (We measure the non-migrating [cached] cost on both
5962 * cpu1 and cpu2, to handle CPUs with different speeds)
5966 measure_one(cache
, size
, cpu1
, cpu1
);
5967 for (i
= 0; i
< ITERATIONS
; i
++)
5968 cost2
+= measure_one(cache
, size
- i
* 1024, cpu1
, cpu1
);
5970 measure_one(cache
, size
, cpu2
, cpu2
);
5971 for (i
= 0; i
< ITERATIONS
; i
++)
5972 cost2
+= measure_one(cache
, size
- i
* 1024, cpu2
, cpu2
);
5975 * Get the per-iteration migration cost:
5977 do_div(cost1
, 2 * ITERATIONS
);
5978 do_div(cost2
, 2 * ITERATIONS
);
5980 return cost1
- cost2
;
5983 static unsigned long long measure_migration_cost(int cpu1
, int cpu2
)
5985 unsigned long long max_cost
= 0, fluct
= 0, avg_fluct
= 0;
5986 unsigned int max_size
, size
, size_found
= 0;
5987 long long cost
= 0, prev_cost
;
5991 * Search from max_cache_size*5 down to 64K - the real relevant
5992 * cachesize has to lie somewhere inbetween.
5994 if (max_cache_size
) {
5995 max_size
= max(max_cache_size
* SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5996 size
= max(max_cache_size
/ SEARCH_SCOPE
, MIN_CACHE_SIZE
);
5999 * Since we have no estimation about the relevant
6002 max_size
= DEFAULT_CACHE_SIZE
* SEARCH_SCOPE
;
6003 size
= MIN_CACHE_SIZE
;
6006 if (!cpu_online(cpu1
) || !cpu_online(cpu2
)) {
6007 printk("cpu %d and %d not both online!\n", cpu1
, cpu2
);
6012 * Allocate the working set:
6014 cache
= vmalloc(max_size
);
6016 printk("could not vmalloc %d bytes for cache!\n", 2 * max_size
);
6017 return 1000000; /* return 1 msec on very small boxen */
6020 while (size
<= max_size
) {
6022 cost
= measure_cost(cpu1
, cpu2
, cache
, size
);
6028 if (max_cost
< cost
) {
6034 * Calculate average fluctuation, we use this to prevent
6035 * noise from triggering an early break out of the loop:
6037 fluct
= abs(cost
- prev_cost
);
6038 avg_fluct
= (avg_fluct
+ fluct
)/2;
6040 if (migration_debug
)
6041 printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): "
6044 (long)cost
/ 1000000,
6045 ((long)cost
/ 100000) % 10,
6046 (long)max_cost
/ 1000000,
6047 ((long)max_cost
/ 100000) % 10,
6048 domain_distance(cpu1
, cpu2
),
6052 * If we iterated at least 20% past the previous maximum,
6053 * and the cost has dropped by more than 20% already,
6054 * (taking fluctuations into account) then we assume to
6055 * have found the maximum and break out of the loop early:
6057 if (size_found
&& (size
*100 > size_found
*SIZE_THRESH
))
6058 if (cost
+avg_fluct
<= 0 ||
6059 max_cost
*100 > (cost
+avg_fluct
)*COST_THRESH
) {
6061 if (migration_debug
)
6062 printk("-> found max.\n");
6066 * Increase the cachesize in 10% steps:
6068 size
= size
* 10 / 9;
6071 if (migration_debug
)
6072 printk("[%d][%d] working set size found: %d, cost: %Ld\n",
6073 cpu1
, cpu2
, size_found
, max_cost
);
6078 * A task is considered 'cache cold' if at least 2 times
6079 * the worst-case cost of migration has passed.
6081 * (this limit is only listened to if the load-balancing
6082 * situation is 'nice' - if there is a large imbalance we
6083 * ignore it for the sake of CPU utilization and
6084 * processing fairness.)
6086 return 2 * max_cost
* migration_factor
/ MIGRATION_FACTOR_SCALE
;
6089 static void calibrate_migration_costs(const cpumask_t
*cpu_map
)
6091 int cpu1
= -1, cpu2
= -1, cpu
, orig_cpu
= raw_smp_processor_id();
6092 unsigned long j0
, j1
, distance
, max_distance
= 0;
6093 struct sched_domain
*sd
;
6098 * First pass - calculate the cacheflush times:
6100 for_each_cpu_mask(cpu1
, *cpu_map
) {
6101 for_each_cpu_mask(cpu2
, *cpu_map
) {
6104 distance
= domain_distance(cpu1
, cpu2
);
6105 max_distance
= max(max_distance
, distance
);
6107 * No result cached yet?
6109 if (migration_cost
[distance
] == -1LL)
6110 migration_cost
[distance
] =
6111 measure_migration_cost(cpu1
, cpu2
);
6115 * Second pass - update the sched domain hierarchy with
6116 * the new cache-hot-time estimations:
6118 for_each_cpu_mask(cpu
, *cpu_map
) {
6120 for_each_domain(cpu
, sd
) {
6121 sd
->cache_hot_time
= migration_cost
[distance
];
6128 if (migration_debug
)
6129 printk("migration: max_cache_size: %d, cpu: %d MHz:\n",
6137 if (system_state
== SYSTEM_BOOTING
&& num_online_cpus() > 1) {
6138 printk("migration_cost=");
6139 for (distance
= 0; distance
<= max_distance
; distance
++) {
6142 printk("%ld", (long)migration_cost
[distance
] / 1000);
6147 if (migration_debug
)
6148 printk("migration: %ld seconds\n", (j1
-j0
) / HZ
);
6151 * Move back to the original CPU. NUMA-Q gets confused
6152 * if we migrate to another quad during bootup.
6154 if (raw_smp_processor_id() != orig_cpu
) {
6155 cpumask_t mask
= cpumask_of_cpu(orig_cpu
),
6156 saved_mask
= current
->cpus_allowed
;
6158 set_cpus_allowed(current
, mask
);
6159 set_cpus_allowed(current
, saved_mask
);
6166 * find_next_best_node - find the next node to include in a sched_domain
6167 * @node: node whose sched_domain we're building
6168 * @used_nodes: nodes already in the sched_domain
6170 * Find the next node to include in a given scheduling domain. Simply
6171 * finds the closest node not already in the @used_nodes map.
6173 * Should use nodemask_t.
6175 static int find_next_best_node(int node
, unsigned long *used_nodes
)
6177 int i
, n
, val
, min_val
, best_node
= 0;
6181 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6182 /* Start at @node */
6183 n
= (node
+ i
) % MAX_NUMNODES
;
6185 if (!nr_cpus_node(n
))
6188 /* Skip already used nodes */
6189 if (test_bit(n
, used_nodes
))
6192 /* Simple min distance search */
6193 val
= node_distance(node
, n
);
6195 if (val
< min_val
) {
6201 set_bit(best_node
, used_nodes
);
6206 * sched_domain_node_span - get a cpumask for a node's sched_domain
6207 * @node: node whose cpumask we're constructing
6208 * @size: number of nodes to include in this span
6210 * Given a node, construct a good cpumask for its sched_domain to span. It
6211 * should be one that prevents unnecessary balancing, but also spreads tasks
6214 static cpumask_t
sched_domain_node_span(int node
)
6216 DECLARE_BITMAP(used_nodes
, MAX_NUMNODES
);
6217 cpumask_t span
, nodemask
;
6221 bitmap_zero(used_nodes
, MAX_NUMNODES
);
6223 nodemask
= node_to_cpumask(node
);
6224 cpus_or(span
, span
, nodemask
);
6225 set_bit(node
, used_nodes
);
6227 for (i
= 1; i
< SD_NODES_PER_DOMAIN
; i
++) {
6228 int next_node
= find_next_best_node(node
, used_nodes
);
6230 nodemask
= node_to_cpumask(next_node
);
6231 cpus_or(span
, span
, nodemask
);
6238 int sched_smt_power_savings
= 0, sched_mc_power_savings
= 0;
6241 * SMT sched-domains:
6243 #ifdef CONFIG_SCHED_SMT
6244 static DEFINE_PER_CPU(struct sched_domain
, cpu_domains
);
6245 static DEFINE_PER_CPU(struct sched_group
, sched_group_cpus
);
6247 static int cpu_to_cpu_group(int cpu
, const cpumask_t
*cpu_map
,
6248 struct sched_group
**sg
)
6251 *sg
= &per_cpu(sched_group_cpus
, cpu
);
6257 * multi-core sched-domains:
6259 #ifdef CONFIG_SCHED_MC
6260 static DEFINE_PER_CPU(struct sched_domain
, core_domains
);
6261 static DEFINE_PER_CPU(struct sched_group
, sched_group_core
);
6264 #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT)
6265 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6266 struct sched_group
**sg
)
6269 cpumask_t mask
= cpu_sibling_map
[cpu
];
6270 cpus_and(mask
, mask
, *cpu_map
);
6271 group
= first_cpu(mask
);
6273 *sg
= &per_cpu(sched_group_core
, group
);
6276 #elif defined(CONFIG_SCHED_MC)
6277 static int cpu_to_core_group(int cpu
, const cpumask_t
*cpu_map
,
6278 struct sched_group
**sg
)
6281 *sg
= &per_cpu(sched_group_core
, cpu
);
6286 static DEFINE_PER_CPU(struct sched_domain
, phys_domains
);
6287 static DEFINE_PER_CPU(struct sched_group
, sched_group_phys
);
6289 static int cpu_to_phys_group(int cpu
, const cpumask_t
*cpu_map
,
6290 struct sched_group
**sg
)
6293 #ifdef CONFIG_SCHED_MC
6294 cpumask_t mask
= cpu_coregroup_map(cpu
);
6295 cpus_and(mask
, mask
, *cpu_map
);
6296 group
= first_cpu(mask
);
6297 #elif defined(CONFIG_SCHED_SMT)
6298 cpumask_t mask
= cpu_sibling_map
[cpu
];
6299 cpus_and(mask
, mask
, *cpu_map
);
6300 group
= first_cpu(mask
);
6305 *sg
= &per_cpu(sched_group_phys
, group
);
6311 * The init_sched_build_groups can't handle what we want to do with node
6312 * groups, so roll our own. Now each node has its own list of groups which
6313 * gets dynamically allocated.
6315 static DEFINE_PER_CPU(struct sched_domain
, node_domains
);
6316 static struct sched_group
**sched_group_nodes_bycpu
[NR_CPUS
];
6318 static DEFINE_PER_CPU(struct sched_domain
, allnodes_domains
);
6319 static DEFINE_PER_CPU(struct sched_group
, sched_group_allnodes
);
6321 static int cpu_to_allnodes_group(int cpu
, const cpumask_t
*cpu_map
,
6322 struct sched_group
**sg
)
6324 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(cpu
));
6327 cpus_and(nodemask
, nodemask
, *cpu_map
);
6328 group
= first_cpu(nodemask
);
6331 *sg
= &per_cpu(sched_group_allnodes
, group
);
6335 static void init_numa_sched_groups_power(struct sched_group
*group_head
)
6337 struct sched_group
*sg
= group_head
;
6343 for_each_cpu_mask(j
, sg
->cpumask
) {
6344 struct sched_domain
*sd
;
6346 sd
= &per_cpu(phys_domains
, j
);
6347 if (j
!= first_cpu(sd
->groups
->cpumask
)) {
6349 * Only add "power" once for each
6355 sg
->cpu_power
+= sd
->groups
->cpu_power
;
6358 if (sg
!= group_head
)
6364 /* Free memory allocated for various sched_group structures */
6365 static void free_sched_groups(const cpumask_t
*cpu_map
)
6369 for_each_cpu_mask(cpu
, *cpu_map
) {
6370 struct sched_group
**sched_group_nodes
6371 = sched_group_nodes_bycpu
[cpu
];
6373 if (!sched_group_nodes
)
6376 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6377 cpumask_t nodemask
= node_to_cpumask(i
);
6378 struct sched_group
*oldsg
, *sg
= sched_group_nodes
[i
];
6380 cpus_and(nodemask
, nodemask
, *cpu_map
);
6381 if (cpus_empty(nodemask
))
6391 if (oldsg
!= sched_group_nodes
[i
])
6394 kfree(sched_group_nodes
);
6395 sched_group_nodes_bycpu
[cpu
] = NULL
;
6399 static void free_sched_groups(const cpumask_t
*cpu_map
)
6405 * Initialize sched groups cpu_power.
6407 * cpu_power indicates the capacity of sched group, which is used while
6408 * distributing the load between different sched groups in a sched domain.
6409 * Typically cpu_power for all the groups in a sched domain will be same unless
6410 * there are asymmetries in the topology. If there are asymmetries, group
6411 * having more cpu_power will pickup more load compared to the group having
6414 * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents
6415 * the maximum number of tasks a group can handle in the presence of other idle
6416 * or lightly loaded groups in the same sched domain.
6418 static void init_sched_groups_power(int cpu
, struct sched_domain
*sd
)
6420 struct sched_domain
*child
;
6421 struct sched_group
*group
;
6423 WARN_ON(!sd
|| !sd
->groups
);
6425 if (cpu
!= first_cpu(sd
->groups
->cpumask
))
6431 * For perf policy, if the groups in child domain share resources
6432 * (for example cores sharing some portions of the cache hierarchy
6433 * or SMT), then set this domain groups cpu_power such that each group
6434 * can handle only one task, when there are other idle groups in the
6435 * same sched domain.
6437 if (!child
|| (!(sd
->flags
& SD_POWERSAVINGS_BALANCE
) &&
6439 (SD_SHARE_CPUPOWER
| SD_SHARE_PKG_RESOURCES
)))) {
6440 sd
->groups
->cpu_power
= SCHED_LOAD_SCALE
;
6444 sd
->groups
->cpu_power
= 0;
6447 * add cpu_power of each child group to this groups cpu_power
6449 group
= child
->groups
;
6451 sd
->groups
->cpu_power
+= group
->cpu_power
;
6452 group
= group
->next
;
6453 } while (group
!= child
->groups
);
6457 * Build sched domains for a given set of cpus and attach the sched domains
6458 * to the individual cpus
6460 static int build_sched_domains(const cpumask_t
*cpu_map
)
6463 struct sched_domain
*sd
;
6465 struct sched_group
**sched_group_nodes
= NULL
;
6466 int sd_allnodes
= 0;
6469 * Allocate the per-node list of sched groups
6471 sched_group_nodes
= kzalloc(sizeof(struct sched_group
*)*MAX_NUMNODES
,
6473 if (!sched_group_nodes
) {
6474 printk(KERN_WARNING
"Can not alloc sched group node list\n");
6477 sched_group_nodes_bycpu
[first_cpu(*cpu_map
)] = sched_group_nodes
;
6481 * Set up domains for cpus specified by the cpu_map.
6483 for_each_cpu_mask(i
, *cpu_map
) {
6484 struct sched_domain
*sd
= NULL
, *p
;
6485 cpumask_t nodemask
= node_to_cpumask(cpu_to_node(i
));
6487 cpus_and(nodemask
, nodemask
, *cpu_map
);
6490 if (cpus_weight(*cpu_map
)
6491 > SD_NODES_PER_DOMAIN
*cpus_weight(nodemask
)) {
6492 sd
= &per_cpu(allnodes_domains
, i
);
6493 *sd
= SD_ALLNODES_INIT
;
6494 sd
->span
= *cpu_map
;
6495 cpu_to_allnodes_group(i
, cpu_map
, &sd
->groups
);
6501 sd
= &per_cpu(node_domains
, i
);
6503 sd
->span
= sched_domain_node_span(cpu_to_node(i
));
6507 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6511 sd
= &per_cpu(phys_domains
, i
);
6513 sd
->span
= nodemask
;
6517 cpu_to_phys_group(i
, cpu_map
, &sd
->groups
);
6519 #ifdef CONFIG_SCHED_MC
6521 sd
= &per_cpu(core_domains
, i
);
6523 sd
->span
= cpu_coregroup_map(i
);
6524 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6527 cpu_to_core_group(i
, cpu_map
, &sd
->groups
);
6530 #ifdef CONFIG_SCHED_SMT
6532 sd
= &per_cpu(cpu_domains
, i
);
6533 *sd
= SD_SIBLING_INIT
;
6534 sd
->span
= cpu_sibling_map
[i
];
6535 cpus_and(sd
->span
, sd
->span
, *cpu_map
);
6538 cpu_to_cpu_group(i
, cpu_map
, &sd
->groups
);
6542 #ifdef CONFIG_SCHED_SMT
6543 /* Set up CPU (sibling) groups */
6544 for_each_cpu_mask(i
, *cpu_map
) {
6545 cpumask_t this_sibling_map
= cpu_sibling_map
[i
];
6546 cpus_and(this_sibling_map
, this_sibling_map
, *cpu_map
);
6547 if (i
!= first_cpu(this_sibling_map
))
6550 init_sched_build_groups(this_sibling_map
, cpu_map
, &cpu_to_cpu_group
);
6554 #ifdef CONFIG_SCHED_MC
6555 /* Set up multi-core groups */
6556 for_each_cpu_mask(i
, *cpu_map
) {
6557 cpumask_t this_core_map
= cpu_coregroup_map(i
);
6558 cpus_and(this_core_map
, this_core_map
, *cpu_map
);
6559 if (i
!= first_cpu(this_core_map
))
6561 init_sched_build_groups(this_core_map
, cpu_map
, &cpu_to_core_group
);
6566 /* Set up physical groups */
6567 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6568 cpumask_t nodemask
= node_to_cpumask(i
);
6570 cpus_and(nodemask
, nodemask
, *cpu_map
);
6571 if (cpus_empty(nodemask
))
6574 init_sched_build_groups(nodemask
, cpu_map
, &cpu_to_phys_group
);
6578 /* Set up node groups */
6580 init_sched_build_groups(*cpu_map
, cpu_map
, &cpu_to_allnodes_group
);
6582 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
6583 /* Set up node groups */
6584 struct sched_group
*sg
, *prev
;
6585 cpumask_t nodemask
= node_to_cpumask(i
);
6586 cpumask_t domainspan
;
6587 cpumask_t covered
= CPU_MASK_NONE
;
6590 cpus_and(nodemask
, nodemask
, *cpu_map
);
6591 if (cpus_empty(nodemask
)) {
6592 sched_group_nodes
[i
] = NULL
;
6596 domainspan
= sched_domain_node_span(i
);
6597 cpus_and(domainspan
, domainspan
, *cpu_map
);
6599 sg
= kmalloc_node(sizeof(struct sched_group
), GFP_KERNEL
, i
);
6601 printk(KERN_WARNING
"Can not alloc domain group for "
6605 sched_group_nodes
[i
] = sg
;
6606 for_each_cpu_mask(j
, nodemask
) {
6607 struct sched_domain
*sd
;
6608 sd
= &per_cpu(node_domains
, j
);
6612 sg
->cpumask
= nodemask
;
6614 cpus_or(covered
, covered
, nodemask
);
6617 for (j
= 0; j
< MAX_NUMNODES
; j
++) {
6618 cpumask_t tmp
, notcovered
;
6619 int n
= (i
+ j
) % MAX_NUMNODES
;
6621 cpus_complement(notcovered
, covered
);
6622 cpus_and(tmp
, notcovered
, *cpu_map
);
6623 cpus_and(tmp
, tmp
, domainspan
);
6624 if (cpus_empty(tmp
))
6627 nodemask
= node_to_cpumask(n
);
6628 cpus_and(tmp
, tmp
, nodemask
);
6629 if (cpus_empty(tmp
))
6632 sg
= kmalloc_node(sizeof(struct sched_group
),
6636 "Can not alloc domain group for node %d\n", j
);
6641 sg
->next
= prev
->next
;
6642 cpus_or(covered
, covered
, tmp
);
6649 /* Calculate CPU power for physical packages and nodes */
6650 #ifdef CONFIG_SCHED_SMT
6651 for_each_cpu_mask(i
, *cpu_map
) {
6652 sd
= &per_cpu(cpu_domains
, i
);
6653 init_sched_groups_power(i
, sd
);
6656 #ifdef CONFIG_SCHED_MC
6657 for_each_cpu_mask(i
, *cpu_map
) {
6658 sd
= &per_cpu(core_domains
, i
);
6659 init_sched_groups_power(i
, sd
);
6663 for_each_cpu_mask(i
, *cpu_map
) {
6664 sd
= &per_cpu(phys_domains
, i
);
6665 init_sched_groups_power(i
, sd
);
6669 for (i
= 0; i
< MAX_NUMNODES
; i
++)
6670 init_numa_sched_groups_power(sched_group_nodes
[i
]);
6673 struct sched_group
*sg
;
6675 cpu_to_allnodes_group(first_cpu(*cpu_map
), cpu_map
, &sg
);
6676 init_numa_sched_groups_power(sg
);
6680 /* Attach the domains */
6681 for_each_cpu_mask(i
, *cpu_map
) {
6682 struct sched_domain
*sd
;
6683 #ifdef CONFIG_SCHED_SMT
6684 sd
= &per_cpu(cpu_domains
, i
);
6685 #elif defined(CONFIG_SCHED_MC)
6686 sd
= &per_cpu(core_domains
, i
);
6688 sd
= &per_cpu(phys_domains
, i
);
6690 cpu_attach_domain(sd
, i
);
6693 * Tune cache-hot values:
6695 calibrate_migration_costs(cpu_map
);
6701 free_sched_groups(cpu_map
);
6706 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
6708 static int arch_init_sched_domains(const cpumask_t
*cpu_map
)
6710 cpumask_t cpu_default_map
;
6714 * Setup mask for cpus without special case scheduling requirements.
6715 * For now this just excludes isolated cpus, but could be used to
6716 * exclude other special cases in the future.
6718 cpus_andnot(cpu_default_map
, *cpu_map
, cpu_isolated_map
);
6720 err
= build_sched_domains(&cpu_default_map
);
6725 static void arch_destroy_sched_domains(const cpumask_t
*cpu_map
)
6727 free_sched_groups(cpu_map
);
6731 * Detach sched domains from a group of cpus specified in cpu_map
6732 * These cpus will now be attached to the NULL domain
6734 static void detach_destroy_domains(const cpumask_t
*cpu_map
)
6738 for_each_cpu_mask(i
, *cpu_map
)
6739 cpu_attach_domain(NULL
, i
);
6740 synchronize_sched();
6741 arch_destroy_sched_domains(cpu_map
);
6745 * Partition sched domains as specified by the cpumasks below.
6746 * This attaches all cpus from the cpumasks to the NULL domain,
6747 * waits for a RCU quiescent period, recalculates sched
6748 * domain information and then attaches them back to the
6749 * correct sched domains
6750 * Call with hotplug lock held
6752 int partition_sched_domains(cpumask_t
*partition1
, cpumask_t
*partition2
)
6754 cpumask_t change_map
;
6757 cpus_and(*partition1
, *partition1
, cpu_online_map
);
6758 cpus_and(*partition2
, *partition2
, cpu_online_map
);
6759 cpus_or(change_map
, *partition1
, *partition2
);
6761 /* Detach sched domains from all of the affected cpus */
6762 detach_destroy_domains(&change_map
);
6763 if (!cpus_empty(*partition1
))
6764 err
= build_sched_domains(partition1
);
6765 if (!err
&& !cpus_empty(*partition2
))
6766 err
= build_sched_domains(partition2
);
6771 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
6772 int arch_reinit_sched_domains(void)
6777 detach_destroy_domains(&cpu_online_map
);
6778 err
= arch_init_sched_domains(&cpu_online_map
);
6779 unlock_cpu_hotplug();
6784 static ssize_t
sched_power_savings_store(const char *buf
, size_t count
, int smt
)
6788 if (buf
[0] != '0' && buf
[0] != '1')
6792 sched_smt_power_savings
= (buf
[0] == '1');
6794 sched_mc_power_savings
= (buf
[0] == '1');
6796 ret
= arch_reinit_sched_domains();
6798 return ret
? ret
: count
;
6801 int sched_create_sysfs_power_savings_entries(struct sysdev_class
*cls
)
6805 #ifdef CONFIG_SCHED_SMT
6807 err
= sysfs_create_file(&cls
->kset
.kobj
,
6808 &attr_sched_smt_power_savings
.attr
);
6810 #ifdef CONFIG_SCHED_MC
6811 if (!err
&& mc_capable())
6812 err
= sysfs_create_file(&cls
->kset
.kobj
,
6813 &attr_sched_mc_power_savings
.attr
);
6819 #ifdef CONFIG_SCHED_MC
6820 static ssize_t
sched_mc_power_savings_show(struct sys_device
*dev
, char *page
)
6822 return sprintf(page
, "%u\n", sched_mc_power_savings
);
6824 static ssize_t
sched_mc_power_savings_store(struct sys_device
*dev
,
6825 const char *buf
, size_t count
)
6827 return sched_power_savings_store(buf
, count
, 0);
6829 SYSDEV_ATTR(sched_mc_power_savings
, 0644, sched_mc_power_savings_show
,
6830 sched_mc_power_savings_store
);
6833 #ifdef CONFIG_SCHED_SMT
6834 static ssize_t
sched_smt_power_savings_show(struct sys_device
*dev
, char *page
)
6836 return sprintf(page
, "%u\n", sched_smt_power_savings
);
6838 static ssize_t
sched_smt_power_savings_store(struct sys_device
*dev
,
6839 const char *buf
, size_t count
)
6841 return sched_power_savings_store(buf
, count
, 1);
6843 SYSDEV_ATTR(sched_smt_power_savings
, 0644, sched_smt_power_savings_show
,
6844 sched_smt_power_savings_store
);
6848 * Force a reinitialization of the sched domains hierarchy. The domains
6849 * and groups cannot be updated in place without racing with the balancing
6850 * code, so we temporarily attach all running cpus to the NULL domain
6851 * which will prevent rebalancing while the sched domains are recalculated.
6853 static int update_sched_domains(struct notifier_block
*nfb
,
6854 unsigned long action
, void *hcpu
)
6857 case CPU_UP_PREPARE
:
6858 case CPU_DOWN_PREPARE
:
6859 detach_destroy_domains(&cpu_online_map
);
6862 case CPU_UP_CANCELED
:
6863 case CPU_DOWN_FAILED
:
6867 * Fall through and re-initialise the domains.
6874 /* The hotplug lock is already held by cpu_up/cpu_down */
6875 arch_init_sched_domains(&cpu_online_map
);
6880 void __init
sched_init_smp(void)
6882 cpumask_t non_isolated_cpus
;
6885 arch_init_sched_domains(&cpu_online_map
);
6886 cpus_andnot(non_isolated_cpus
, cpu_possible_map
, cpu_isolated_map
);
6887 if (cpus_empty(non_isolated_cpus
))
6888 cpu_set(smp_processor_id(), non_isolated_cpus
);
6889 unlock_cpu_hotplug();
6890 /* XXX: Theoretical race here - CPU may be hotplugged now */
6891 hotcpu_notifier(update_sched_domains
, 0);
6893 /* Move init over to a non-isolated CPU */
6894 if (set_cpus_allowed(current
, non_isolated_cpus
) < 0)
6898 void __init
sched_init_smp(void)
6901 #endif /* CONFIG_SMP */
6903 int in_sched_functions(unsigned long addr
)
6905 /* Linker adds these: start and end of __sched functions */
6906 extern char __sched_text_start
[], __sched_text_end
[];
6908 return in_lock_functions(addr
) ||
6909 (addr
>= (unsigned long)__sched_text_start
6910 && addr
< (unsigned long)__sched_text_end
);
6913 void __init
sched_init(void)
6917 for_each_possible_cpu(i
) {
6918 struct prio_array
*array
;
6922 spin_lock_init(&rq
->lock
);
6923 lockdep_set_class(&rq
->lock
, &rq
->rq_lock_key
);
6925 rq
->active
= rq
->arrays
;
6926 rq
->expired
= rq
->arrays
+ 1;
6927 rq
->best_expired_prio
= MAX_PRIO
;
6931 for (j
= 1; j
< 3; j
++)
6932 rq
->cpu_load
[j
] = 0;
6933 rq
->active_balance
= 0;
6936 rq
->migration_thread
= NULL
;
6937 INIT_LIST_HEAD(&rq
->migration_queue
);
6939 atomic_set(&rq
->nr_iowait
, 0);
6941 for (j
= 0; j
< 2; j
++) {
6942 array
= rq
->arrays
+ j
;
6943 for (k
= 0; k
< MAX_PRIO
; k
++) {
6944 INIT_LIST_HEAD(array
->queue
+ k
);
6945 __clear_bit(k
, array
->bitmap
);
6947 // delimiter for bitsearch
6948 __set_bit(MAX_PRIO
, array
->bitmap
);
6952 set_load_weight(&init_task
);
6955 open_softirq(SCHED_SOFTIRQ
, run_rebalance_domains
, NULL
);
6958 #ifdef CONFIG_RT_MUTEXES
6959 plist_head_init(&init_task
.pi_waiters
, &init_task
.pi_lock
);
6963 * The boot idle thread does lazy MMU switching as well:
6965 atomic_inc(&init_mm
.mm_count
);
6966 enter_lazy_tlb(&init_mm
, current
);
6969 * Make us the idle thread. Technically, schedule() should not be
6970 * called from this thread, however somewhere below it might be,
6971 * but because we are the idle thread, we just pick up running again
6972 * when this runqueue becomes "idle".
6974 init_idle(current
, smp_processor_id());
6977 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
6978 void __might_sleep(char *file
, int line
)
6981 static unsigned long prev_jiffy
; /* ratelimiting */
6983 if ((in_atomic() || irqs_disabled()) &&
6984 system_state
== SYSTEM_RUNNING
&& !oops_in_progress
) {
6985 if (time_before(jiffies
, prev_jiffy
+ HZ
) && prev_jiffy
)
6987 prev_jiffy
= jiffies
;
6988 printk(KERN_ERR
"BUG: sleeping function called from invalid"
6989 " context at %s:%d\n", file
, line
);
6990 printk("in_atomic():%d, irqs_disabled():%d\n",
6991 in_atomic(), irqs_disabled());
6992 debug_show_held_locks(current
);
6993 if (irqs_disabled())
6994 print_irqtrace_events(current
);
6999 EXPORT_SYMBOL(__might_sleep
);
7002 #ifdef CONFIG_MAGIC_SYSRQ
7003 void normalize_rt_tasks(void)
7005 struct prio_array
*array
;
7006 struct task_struct
*p
;
7007 unsigned long flags
;
7010 read_lock_irq(&tasklist_lock
);
7011 for_each_process(p
) {
7015 spin_lock_irqsave(&p
->pi_lock
, flags
);
7016 rq
= __task_rq_lock(p
);
7020 deactivate_task(p
, task_rq(p
));
7021 __setscheduler(p
, SCHED_NORMAL
, 0);
7023 __activate_task(p
, task_rq(p
));
7024 resched_task(rq
->curr
);
7027 __task_rq_unlock(rq
);
7028 spin_unlock_irqrestore(&p
->pi_lock
, flags
);
7030 read_unlock_irq(&tasklist_lock
);
7033 #endif /* CONFIG_MAGIC_SYSRQ */
7037 * These functions are only useful for the IA64 MCA handling.
7039 * They can only be called when the whole system has been
7040 * stopped - every CPU needs to be quiescent, and no scheduling
7041 * activity can take place. Using them for anything else would
7042 * be a serious bug, and as a result, they aren't even visible
7043 * under any other configuration.
7047 * curr_task - return the current task for a given cpu.
7048 * @cpu: the processor in question.
7050 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7052 struct task_struct
*curr_task(int cpu
)
7054 return cpu_curr(cpu
);
7058 * set_curr_task - set the current task for a given cpu.
7059 * @cpu: the processor in question.
7060 * @p: the task pointer to set.
7062 * Description: This function must only be used when non-maskable interrupts
7063 * are serviced on a separate stack. It allows the architecture to switch the
7064 * notion of the current task on a cpu in a non-blocking manner. This function
7065 * must be called with all CPU's synchronized, and interrupts disabled, the
7066 * and caller must save the original value of the current task (see
7067 * curr_task() above) and restore that value before reenabling interrupts and
7068 * re-starting the system.
7070 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
7072 void set_curr_task(int cpu
, struct task_struct
*p
)