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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * kernel/sched.c | |
3 | * | |
4 | * Kernel scheduler and related syscalls | |
5 | * | |
6 | * Copyright (C) 1991-2002 Linus Torvalds | |
7 | * | |
8 | * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and | |
9 | * make semaphores SMP safe | |
10 | * 1998-11-19 Implemented schedule_timeout() and related stuff | |
11 | * by Andrea Arcangeli | |
12 | * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: | |
13 | * hybrid priority-list and round-robin design with | |
14 | * an array-switch method of distributing timeslices | |
15 | * and per-CPU runqueues. Cleanups and useful suggestions | |
16 | * by Davide Libenzi, preemptible kernel bits by Robert Love. | |
17 | * 2003-09-03 Interactivity tuning by Con Kolivas. | |
18 | * 2004-04-02 Scheduler domains code by Nick Piggin | |
19 | */ | |
20 | ||
21 | #include <linux/mm.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/nmi.h> | |
24 | #include <linux/init.h> | |
25 | #include <asm/uaccess.h> | |
26 | #include <linux/highmem.h> | |
27 | #include <linux/smp_lock.h> | |
28 | #include <asm/mmu_context.h> | |
29 | #include <linux/interrupt.h> | |
c59ede7b | 30 | #include <linux/capability.h> |
1da177e4 LT |
31 | #include <linux/completion.h> |
32 | #include <linux/kernel_stat.h> | |
9a11b49a | 33 | #include <linux/debug_locks.h> |
1da177e4 LT |
34 | #include <linux/security.h> |
35 | #include <linux/notifier.h> | |
36 | #include <linux/profile.h> | |
7dfb7103 | 37 | #include <linux/freezer.h> |
198e2f18 | 38 | #include <linux/vmalloc.h> |
1da177e4 LT |
39 | #include <linux/blkdev.h> |
40 | #include <linux/delay.h> | |
41 | #include <linux/smp.h> | |
42 | #include <linux/threads.h> | |
43 | #include <linux/timer.h> | |
44 | #include <linux/rcupdate.h> | |
45 | #include <linux/cpu.h> | |
46 | #include <linux/cpuset.h> | |
47 | #include <linux/percpu.h> | |
48 | #include <linux/kthread.h> | |
49 | #include <linux/seq_file.h> | |
50 | #include <linux/syscalls.h> | |
51 | #include <linux/times.h> | |
8f0ab514 | 52 | #include <linux/tsacct_kern.h> |
c6fd91f0 | 53 | #include <linux/kprobes.h> |
0ff92245 | 54 | #include <linux/delayacct.h> |
1da177e4 LT |
55 | #include <asm/tlb.h> |
56 | ||
57 | #include <asm/unistd.h> | |
58 | ||
59 | /* | |
60 | * Convert user-nice values [ -20 ... 0 ... 19 ] | |
61 | * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ], | |
62 | * and back. | |
63 | */ | |
64 | #define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20) | |
65 | #define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20) | |
66 | #define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio) | |
67 | ||
68 | /* | |
69 | * 'User priority' is the nice value converted to something we | |
70 | * can work with better when scaling various scheduler parameters, | |
71 | * it's a [ 0 ... 39 ] range. | |
72 | */ | |
73 | #define USER_PRIO(p) ((p)-MAX_RT_PRIO) | |
74 | #define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio) | |
75 | #define MAX_USER_PRIO (USER_PRIO(MAX_PRIO)) | |
76 | ||
77 | /* | |
78 | * Some helpers for converting nanosecond timing to jiffy resolution | |
79 | */ | |
80 | #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) | |
81 | #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) | |
82 | ||
83 | /* | |
84 | * These are the 'tuning knobs' of the scheduler: | |
85 | * | |
86 | * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger), | |
87 | * default timeslice is 100 msecs, maximum timeslice is 800 msecs. | |
88 | * Timeslices get refilled after they expire. | |
89 | */ | |
90 | #define MIN_TIMESLICE max(5 * HZ / 1000, 1) | |
91 | #define DEF_TIMESLICE (100 * HZ / 1000) | |
92 | #define ON_RUNQUEUE_WEIGHT 30 | |
93 | #define CHILD_PENALTY 95 | |
94 | #define PARENT_PENALTY 100 | |
95 | #define EXIT_WEIGHT 3 | |
96 | #define PRIO_BONUS_RATIO 25 | |
97 | #define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100) | |
98 | #define INTERACTIVE_DELTA 2 | |
99 | #define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS) | |
100 | #define STARVATION_LIMIT (MAX_SLEEP_AVG) | |
101 | #define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG)) | |
102 | ||
103 | /* | |
104 | * If a task is 'interactive' then we reinsert it in the active | |
105 | * array after it has expired its current timeslice. (it will not | |
106 | * continue to run immediately, it will still roundrobin with | |
107 | * other interactive tasks.) | |
108 | * | |
109 | * This part scales the interactivity limit depending on niceness. | |
110 | * | |
111 | * We scale it linearly, offset by the INTERACTIVE_DELTA delta. | |
112 | * Here are a few examples of different nice levels: | |
113 | * | |
114 | * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0] | |
115 | * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0] | |
116 | * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0] | |
117 | * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0] | |
118 | * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0] | |
119 | * | |
120 | * (the X axis represents the possible -5 ... 0 ... +5 dynamic | |
121 | * priority range a task can explore, a value of '1' means the | |
122 | * task is rated interactive.) | |
123 | * | |
124 | * Ie. nice +19 tasks can never get 'interactive' enough to be | |
125 | * reinserted into the active array. And only heavily CPU-hog nice -20 | |
126 | * tasks will be expired. Default nice 0 tasks are somewhere between, | |
127 | * it takes some effort for them to get interactive, but it's not | |
128 | * too hard. | |
129 | */ | |
130 | ||
131 | #define CURRENT_BONUS(p) \ | |
132 | (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \ | |
133 | MAX_SLEEP_AVG) | |
134 | ||
135 | #define GRANULARITY (10 * HZ / 1000 ? : 1) | |
136 | ||
137 | #ifdef CONFIG_SMP | |
138 | #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ | |
139 | (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \ | |
140 | num_online_cpus()) | |
141 | #else | |
142 | #define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ | |
143 | (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1))) | |
144 | #endif | |
145 | ||
146 | #define SCALE(v1,v1_max,v2_max) \ | |
147 | (v1) * (v2_max) / (v1_max) | |
148 | ||
149 | #define DELTA(p) \ | |
013d3868 MA |
150 | (SCALE(TASK_NICE(p) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \ |
151 | INTERACTIVE_DELTA) | |
1da177e4 LT |
152 | |
153 | #define TASK_INTERACTIVE(p) \ | |
154 | ((p)->prio <= (p)->static_prio - DELTA(p)) | |
155 | ||
156 | #define INTERACTIVE_SLEEP(p) \ | |
157 | (JIFFIES_TO_NS(MAX_SLEEP_AVG * \ | |
158 | (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1)) | |
159 | ||
160 | #define TASK_PREEMPTS_CURR(p, rq) \ | |
161 | ((p)->prio < (rq)->curr->prio) | |
162 | ||
1da177e4 | 163 | #define SCALE_PRIO(x, prio) \ |
2dd73a4f | 164 | max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO / 2), MIN_TIMESLICE) |
1da177e4 | 165 | |
2dd73a4f | 166 | static unsigned int static_prio_timeslice(int static_prio) |
1da177e4 | 167 | { |
2dd73a4f PW |
168 | if (static_prio < NICE_TO_PRIO(0)) |
169 | return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio); | |
1da177e4 | 170 | else |
2dd73a4f | 171 | return SCALE_PRIO(DEF_TIMESLICE, static_prio); |
1da177e4 | 172 | } |
2dd73a4f | 173 | |
91fcdd4e BP |
174 | /* |
175 | * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ] | |
176 | * to time slice values: [800ms ... 100ms ... 5ms] | |
177 | * | |
178 | * The higher a thread's priority, the bigger timeslices | |
179 | * it gets during one round of execution. But even the lowest | |
180 | * priority thread gets MIN_TIMESLICE worth of execution time. | |
181 | */ | |
182 | ||
36c8b586 | 183 | static inline unsigned int task_timeslice(struct task_struct *p) |
2dd73a4f PW |
184 | { |
185 | return static_prio_timeslice(p->static_prio); | |
186 | } | |
187 | ||
1da177e4 LT |
188 | /* |
189 | * These are the runqueue data structures: | |
190 | */ | |
191 | ||
1da177e4 LT |
192 | struct prio_array { |
193 | unsigned int nr_active; | |
d444886e | 194 | DECLARE_BITMAP(bitmap, MAX_PRIO+1); /* include 1 bit for delimiter */ |
1da177e4 LT |
195 | struct list_head queue[MAX_PRIO]; |
196 | }; | |
197 | ||
198 | /* | |
199 | * This is the main, per-CPU runqueue data structure. | |
200 | * | |
201 | * Locking rule: those places that want to lock multiple runqueues | |
202 | * (such as the load balancing or the thread migration code), lock | |
203 | * acquire operations must be ordered by ascending &runqueue. | |
204 | */ | |
70b97a7f | 205 | struct rq { |
1da177e4 LT |
206 | spinlock_t lock; |
207 | ||
208 | /* | |
209 | * nr_running and cpu_load should be in the same cacheline because | |
210 | * remote CPUs use both these fields when doing load calculation. | |
211 | */ | |
212 | unsigned long nr_running; | |
2dd73a4f | 213 | unsigned long raw_weighted_load; |
1da177e4 | 214 | #ifdef CONFIG_SMP |
7897986b | 215 | unsigned long cpu_load[3]; |
1da177e4 LT |
216 | #endif |
217 | unsigned long long nr_switches; | |
218 | ||
219 | /* | |
220 | * This is part of a global counter where only the total sum | |
221 | * over all CPUs matters. A task can increase this counter on | |
222 | * one CPU and if it got migrated afterwards it may decrease | |
223 | * it on another CPU. Always updated under the runqueue lock: | |
224 | */ | |
225 | unsigned long nr_uninterruptible; | |
226 | ||
227 | unsigned long expired_timestamp; | |
228 | unsigned long long timestamp_last_tick; | |
36c8b586 | 229 | struct task_struct *curr, *idle; |
c9819f45 | 230 | unsigned long next_balance; |
1da177e4 | 231 | struct mm_struct *prev_mm; |
70b97a7f | 232 | struct prio_array *active, *expired, arrays[2]; |
1da177e4 LT |
233 | int best_expired_prio; |
234 | atomic_t nr_iowait; | |
235 | ||
236 | #ifdef CONFIG_SMP | |
237 | struct sched_domain *sd; | |
238 | ||
239 | /* For active balancing */ | |
240 | int active_balance; | |
241 | int push_cpu; | |
0a2966b4 | 242 | int cpu; /* cpu of this runqueue */ |
1da177e4 | 243 | |
36c8b586 | 244 | struct task_struct *migration_thread; |
1da177e4 LT |
245 | struct list_head migration_queue; |
246 | #endif | |
247 | ||
248 | #ifdef CONFIG_SCHEDSTATS | |
249 | /* latency stats */ | |
250 | struct sched_info rq_sched_info; | |
251 | ||
252 | /* sys_sched_yield() stats */ | |
253 | unsigned long yld_exp_empty; | |
254 | unsigned long yld_act_empty; | |
255 | unsigned long yld_both_empty; | |
256 | unsigned long yld_cnt; | |
257 | ||
258 | /* schedule() stats */ | |
259 | unsigned long sched_switch; | |
260 | unsigned long sched_cnt; | |
261 | unsigned long sched_goidle; | |
262 | ||
263 | /* try_to_wake_up() stats */ | |
264 | unsigned long ttwu_cnt; | |
265 | unsigned long ttwu_local; | |
266 | #endif | |
fcb99371 | 267 | struct lock_class_key rq_lock_key; |
1da177e4 LT |
268 | }; |
269 | ||
70b97a7f | 270 | static DEFINE_PER_CPU(struct rq, runqueues); |
1da177e4 | 271 | |
0a2966b4 CL |
272 | static inline int cpu_of(struct rq *rq) |
273 | { | |
274 | #ifdef CONFIG_SMP | |
275 | return rq->cpu; | |
276 | #else | |
277 | return 0; | |
278 | #endif | |
279 | } | |
280 | ||
674311d5 NP |
281 | /* |
282 | * The domain tree (rq->sd) is protected by RCU's quiescent state transition. | |
1a20ff27 | 283 | * See detach_destroy_domains: synchronize_sched for details. |
674311d5 NP |
284 | * |
285 | * The domain tree of any CPU may only be accessed from within | |
286 | * preempt-disabled sections. | |
287 | */ | |
48f24c4d IM |
288 | #define for_each_domain(cpu, __sd) \ |
289 | for (__sd = rcu_dereference(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent) | |
1da177e4 LT |
290 | |
291 | #define cpu_rq(cpu) (&per_cpu(runqueues, (cpu))) | |
292 | #define this_rq() (&__get_cpu_var(runqueues)) | |
293 | #define task_rq(p) cpu_rq(task_cpu(p)) | |
294 | #define cpu_curr(cpu) (cpu_rq(cpu)->curr) | |
295 | ||
1da177e4 | 296 | #ifndef prepare_arch_switch |
4866cde0 NP |
297 | # define prepare_arch_switch(next) do { } while (0) |
298 | #endif | |
299 | #ifndef finish_arch_switch | |
300 | # define finish_arch_switch(prev) do { } while (0) | |
301 | #endif | |
302 | ||
303 | #ifndef __ARCH_WANT_UNLOCKED_CTXSW | |
70b97a7f | 304 | static inline int task_running(struct rq *rq, struct task_struct *p) |
4866cde0 NP |
305 | { |
306 | return rq->curr == p; | |
307 | } | |
308 | ||
70b97a7f | 309 | static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) |
4866cde0 NP |
310 | { |
311 | } | |
312 | ||
70b97a7f | 313 | static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) |
4866cde0 | 314 | { |
da04c035 IM |
315 | #ifdef CONFIG_DEBUG_SPINLOCK |
316 | /* this is a valid case when another task releases the spinlock */ | |
317 | rq->lock.owner = current; | |
318 | #endif | |
8a25d5de IM |
319 | /* |
320 | * If we are tracking spinlock dependencies then we have to | |
321 | * fix up the runqueue lock - which gets 'carried over' from | |
322 | * prev into current: | |
323 | */ | |
324 | spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_); | |
325 | ||
4866cde0 NP |
326 | spin_unlock_irq(&rq->lock); |
327 | } | |
328 | ||
329 | #else /* __ARCH_WANT_UNLOCKED_CTXSW */ | |
70b97a7f | 330 | static inline int task_running(struct rq *rq, struct task_struct *p) |
4866cde0 NP |
331 | { |
332 | #ifdef CONFIG_SMP | |
333 | return p->oncpu; | |
334 | #else | |
335 | return rq->curr == p; | |
336 | #endif | |
337 | } | |
338 | ||
70b97a7f | 339 | static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) |
4866cde0 NP |
340 | { |
341 | #ifdef CONFIG_SMP | |
342 | /* | |
343 | * We can optimise this out completely for !SMP, because the | |
344 | * SMP rebalancing from interrupt is the only thing that cares | |
345 | * here. | |
346 | */ | |
347 | next->oncpu = 1; | |
348 | #endif | |
349 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW | |
350 | spin_unlock_irq(&rq->lock); | |
351 | #else | |
352 | spin_unlock(&rq->lock); | |
353 | #endif | |
354 | } | |
355 | ||
70b97a7f | 356 | static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) |
4866cde0 NP |
357 | { |
358 | #ifdef CONFIG_SMP | |
359 | /* | |
360 | * After ->oncpu is cleared, the task can be moved to a different CPU. | |
361 | * We must ensure this doesn't happen until the switch is completely | |
362 | * finished. | |
363 | */ | |
364 | smp_wmb(); | |
365 | prev->oncpu = 0; | |
366 | #endif | |
367 | #ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW | |
368 | local_irq_enable(); | |
1da177e4 | 369 | #endif |
4866cde0 NP |
370 | } |
371 | #endif /* __ARCH_WANT_UNLOCKED_CTXSW */ | |
1da177e4 | 372 | |
b29739f9 IM |
373 | /* |
374 | * __task_rq_lock - lock the runqueue a given task resides on. | |
375 | * Must be called interrupts disabled. | |
376 | */ | |
70b97a7f | 377 | static inline struct rq *__task_rq_lock(struct task_struct *p) |
b29739f9 IM |
378 | __acquires(rq->lock) |
379 | { | |
70b97a7f | 380 | struct rq *rq; |
b29739f9 IM |
381 | |
382 | repeat_lock_task: | |
383 | rq = task_rq(p); | |
384 | spin_lock(&rq->lock); | |
385 | if (unlikely(rq != task_rq(p))) { | |
386 | spin_unlock(&rq->lock); | |
387 | goto repeat_lock_task; | |
388 | } | |
389 | return rq; | |
390 | } | |
391 | ||
1da177e4 LT |
392 | /* |
393 | * task_rq_lock - lock the runqueue a given task resides on and disable | |
394 | * interrupts. Note the ordering: we can safely lookup the task_rq without | |
395 | * explicitly disabling preemption. | |
396 | */ | |
70b97a7f | 397 | static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags) |
1da177e4 LT |
398 | __acquires(rq->lock) |
399 | { | |
70b97a7f | 400 | struct rq *rq; |
1da177e4 LT |
401 | |
402 | repeat_lock_task: | |
403 | local_irq_save(*flags); | |
404 | rq = task_rq(p); | |
405 | spin_lock(&rq->lock); | |
406 | if (unlikely(rq != task_rq(p))) { | |
407 | spin_unlock_irqrestore(&rq->lock, *flags); | |
408 | goto repeat_lock_task; | |
409 | } | |
410 | return rq; | |
411 | } | |
412 | ||
70b97a7f | 413 | static inline void __task_rq_unlock(struct rq *rq) |
b29739f9 IM |
414 | __releases(rq->lock) |
415 | { | |
416 | spin_unlock(&rq->lock); | |
417 | } | |
418 | ||
70b97a7f | 419 | static inline void task_rq_unlock(struct rq *rq, unsigned long *flags) |
1da177e4 LT |
420 | __releases(rq->lock) |
421 | { | |
422 | spin_unlock_irqrestore(&rq->lock, *flags); | |
423 | } | |
424 | ||
425 | #ifdef CONFIG_SCHEDSTATS | |
426 | /* | |
427 | * bump this up when changing the output format or the meaning of an existing | |
428 | * format, so that tools can adapt (or abort) | |
429 | */ | |
68767a0a | 430 | #define SCHEDSTAT_VERSION 12 |
1da177e4 LT |
431 | |
432 | static int show_schedstat(struct seq_file *seq, void *v) | |
433 | { | |
434 | int cpu; | |
435 | ||
436 | seq_printf(seq, "version %d\n", SCHEDSTAT_VERSION); | |
437 | seq_printf(seq, "timestamp %lu\n", jiffies); | |
438 | for_each_online_cpu(cpu) { | |
70b97a7f | 439 | struct rq *rq = cpu_rq(cpu); |
1da177e4 LT |
440 | #ifdef CONFIG_SMP |
441 | struct sched_domain *sd; | |
442 | int dcnt = 0; | |
443 | #endif | |
444 | ||
445 | /* runqueue-specific stats */ | |
446 | seq_printf(seq, | |
447 | "cpu%d %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu", | |
448 | cpu, rq->yld_both_empty, | |
449 | rq->yld_act_empty, rq->yld_exp_empty, rq->yld_cnt, | |
450 | rq->sched_switch, rq->sched_cnt, rq->sched_goidle, | |
451 | rq->ttwu_cnt, rq->ttwu_local, | |
452 | rq->rq_sched_info.cpu_time, | |
453 | rq->rq_sched_info.run_delay, rq->rq_sched_info.pcnt); | |
454 | ||
455 | seq_printf(seq, "\n"); | |
456 | ||
457 | #ifdef CONFIG_SMP | |
458 | /* domain-specific stats */ | |
674311d5 | 459 | preempt_disable(); |
1da177e4 LT |
460 | for_each_domain(cpu, sd) { |
461 | enum idle_type itype; | |
462 | char mask_str[NR_CPUS]; | |
463 | ||
464 | cpumask_scnprintf(mask_str, NR_CPUS, sd->span); | |
465 | seq_printf(seq, "domain%d %s", dcnt++, mask_str); | |
466 | for (itype = SCHED_IDLE; itype < MAX_IDLE_TYPES; | |
467 | itype++) { | |
468 | seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu", | |
469 | sd->lb_cnt[itype], | |
470 | sd->lb_balanced[itype], | |
471 | sd->lb_failed[itype], | |
472 | sd->lb_imbalance[itype], | |
473 | sd->lb_gained[itype], | |
474 | sd->lb_hot_gained[itype], | |
475 | sd->lb_nobusyq[itype], | |
476 | sd->lb_nobusyg[itype]); | |
477 | } | |
68767a0a | 478 | seq_printf(seq, " %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n", |
1da177e4 | 479 | sd->alb_cnt, sd->alb_failed, sd->alb_pushed, |
68767a0a NP |
480 | sd->sbe_cnt, sd->sbe_balanced, sd->sbe_pushed, |
481 | sd->sbf_cnt, sd->sbf_balanced, sd->sbf_pushed, | |
1da177e4 LT |
482 | sd->ttwu_wake_remote, sd->ttwu_move_affine, sd->ttwu_move_balance); |
483 | } | |
674311d5 | 484 | preempt_enable(); |
1da177e4 LT |
485 | #endif |
486 | } | |
487 | return 0; | |
488 | } | |
489 | ||
490 | static int schedstat_open(struct inode *inode, struct file *file) | |
491 | { | |
492 | unsigned int size = PAGE_SIZE * (1 + num_online_cpus() / 32); | |
493 | char *buf = kmalloc(size, GFP_KERNEL); | |
494 | struct seq_file *m; | |
495 | int res; | |
496 | ||
497 | if (!buf) | |
498 | return -ENOMEM; | |
499 | res = single_open(file, show_schedstat, NULL); | |
500 | if (!res) { | |
501 | m = file->private_data; | |
502 | m->buf = buf; | |
503 | m->size = size; | |
504 | } else | |
505 | kfree(buf); | |
506 | return res; | |
507 | } | |
508 | ||
15ad7cdc | 509 | const struct file_operations proc_schedstat_operations = { |
1da177e4 LT |
510 | .open = schedstat_open, |
511 | .read = seq_read, | |
512 | .llseek = seq_lseek, | |
513 | .release = single_release, | |
514 | }; | |
515 | ||
52f17b6c CS |
516 | /* |
517 | * Expects runqueue lock to be held for atomicity of update | |
518 | */ | |
519 | static inline void | |
520 | rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies) | |
521 | { | |
522 | if (rq) { | |
523 | rq->rq_sched_info.run_delay += delta_jiffies; | |
524 | rq->rq_sched_info.pcnt++; | |
525 | } | |
526 | } | |
527 | ||
528 | /* | |
529 | * Expects runqueue lock to be held for atomicity of update | |
530 | */ | |
531 | static inline void | |
532 | rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies) | |
533 | { | |
534 | if (rq) | |
535 | rq->rq_sched_info.cpu_time += delta_jiffies; | |
536 | } | |
1da177e4 LT |
537 | # define schedstat_inc(rq, field) do { (rq)->field++; } while (0) |
538 | # define schedstat_add(rq, field, amt) do { (rq)->field += (amt); } while (0) | |
539 | #else /* !CONFIG_SCHEDSTATS */ | |
52f17b6c CS |
540 | static inline void |
541 | rq_sched_info_arrive(struct rq *rq, unsigned long delta_jiffies) | |
542 | {} | |
543 | static inline void | |
544 | rq_sched_info_depart(struct rq *rq, unsigned long delta_jiffies) | |
545 | {} | |
1da177e4 LT |
546 | # define schedstat_inc(rq, field) do { } while (0) |
547 | # define schedstat_add(rq, field, amt) do { } while (0) | |
548 | #endif | |
549 | ||
550 | /* | |
cc2a73b5 | 551 | * this_rq_lock - lock this runqueue and disable interrupts. |
1da177e4 | 552 | */ |
70b97a7f | 553 | static inline struct rq *this_rq_lock(void) |
1da177e4 LT |
554 | __acquires(rq->lock) |
555 | { | |
70b97a7f | 556 | struct rq *rq; |
1da177e4 LT |
557 | |
558 | local_irq_disable(); | |
559 | rq = this_rq(); | |
560 | spin_lock(&rq->lock); | |
561 | ||
562 | return rq; | |
563 | } | |
564 | ||
52f17b6c | 565 | #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) |
1da177e4 LT |
566 | /* |
567 | * Called when a process is dequeued from the active array and given | |
568 | * the cpu. We should note that with the exception of interactive | |
569 | * tasks, the expired queue will become the active queue after the active | |
570 | * queue is empty, without explicitly dequeuing and requeuing tasks in the | |
571 | * expired queue. (Interactive tasks may be requeued directly to the | |
572 | * active queue, thus delaying tasks in the expired queue from running; | |
573 | * see scheduler_tick()). | |
574 | * | |
575 | * This function is only called from sched_info_arrive(), rather than | |
576 | * dequeue_task(). Even though a task may be queued and dequeued multiple | |
577 | * times as it is shuffled about, we're really interested in knowing how | |
578 | * long it was from the *first* time it was queued to the time that it | |
579 | * finally hit a cpu. | |
580 | */ | |
36c8b586 | 581 | static inline void sched_info_dequeued(struct task_struct *t) |
1da177e4 LT |
582 | { |
583 | t->sched_info.last_queued = 0; | |
584 | } | |
585 | ||
586 | /* | |
587 | * Called when a task finally hits the cpu. We can now calculate how | |
588 | * long it was waiting to run. We also note when it began so that we | |
589 | * can keep stats on how long its timeslice is. | |
590 | */ | |
36c8b586 | 591 | static void sched_info_arrive(struct task_struct *t) |
1da177e4 | 592 | { |
52f17b6c | 593 | unsigned long now = jiffies, delta_jiffies = 0; |
1da177e4 LT |
594 | |
595 | if (t->sched_info.last_queued) | |
52f17b6c | 596 | delta_jiffies = now - t->sched_info.last_queued; |
1da177e4 | 597 | sched_info_dequeued(t); |
52f17b6c | 598 | t->sched_info.run_delay += delta_jiffies; |
1da177e4 LT |
599 | t->sched_info.last_arrival = now; |
600 | t->sched_info.pcnt++; | |
601 | ||
52f17b6c | 602 | rq_sched_info_arrive(task_rq(t), delta_jiffies); |
1da177e4 LT |
603 | } |
604 | ||
605 | /* | |
606 | * Called when a process is queued into either the active or expired | |
607 | * array. The time is noted and later used to determine how long we | |
608 | * had to wait for us to reach the cpu. Since the expired queue will | |
609 | * become the active queue after active queue is empty, without dequeuing | |
610 | * and requeuing any tasks, we are interested in queuing to either. It | |
611 | * is unusual but not impossible for tasks to be dequeued and immediately | |
612 | * requeued in the same or another array: this can happen in sched_yield(), | |
613 | * set_user_nice(), and even load_balance() as it moves tasks from runqueue | |
614 | * to runqueue. | |
615 | * | |
616 | * This function is only called from enqueue_task(), but also only updates | |
617 | * the timestamp if it is already not set. It's assumed that | |
618 | * sched_info_dequeued() will clear that stamp when appropriate. | |
619 | */ | |
36c8b586 | 620 | static inline void sched_info_queued(struct task_struct *t) |
1da177e4 | 621 | { |
52f17b6c CS |
622 | if (unlikely(sched_info_on())) |
623 | if (!t->sched_info.last_queued) | |
624 | t->sched_info.last_queued = jiffies; | |
1da177e4 LT |
625 | } |
626 | ||
627 | /* | |
628 | * Called when a process ceases being the active-running process, either | |
629 | * voluntarily or involuntarily. Now we can calculate how long we ran. | |
630 | */ | |
36c8b586 | 631 | static inline void sched_info_depart(struct task_struct *t) |
1da177e4 | 632 | { |
52f17b6c | 633 | unsigned long delta_jiffies = jiffies - t->sched_info.last_arrival; |
1da177e4 | 634 | |
52f17b6c CS |
635 | t->sched_info.cpu_time += delta_jiffies; |
636 | rq_sched_info_depart(task_rq(t), delta_jiffies); | |
1da177e4 LT |
637 | } |
638 | ||
639 | /* | |
640 | * Called when tasks are switched involuntarily due, typically, to expiring | |
641 | * their time slice. (This may also be called when switching to or from | |
642 | * the idle task.) We are only called when prev != next. | |
643 | */ | |
36c8b586 | 644 | static inline void |
52f17b6c | 645 | __sched_info_switch(struct task_struct *prev, struct task_struct *next) |
1da177e4 | 646 | { |
70b97a7f | 647 | struct rq *rq = task_rq(prev); |
1da177e4 LT |
648 | |
649 | /* | |
650 | * prev now departs the cpu. It's not interesting to record | |
651 | * stats about how efficient we were at scheduling the idle | |
652 | * process, however. | |
653 | */ | |
654 | if (prev != rq->idle) | |
655 | sched_info_depart(prev); | |
656 | ||
657 | if (next != rq->idle) | |
658 | sched_info_arrive(next); | |
659 | } | |
52f17b6c CS |
660 | static inline void |
661 | sched_info_switch(struct task_struct *prev, struct task_struct *next) | |
662 | { | |
663 | if (unlikely(sched_info_on())) | |
664 | __sched_info_switch(prev, next); | |
665 | } | |
1da177e4 LT |
666 | #else |
667 | #define sched_info_queued(t) do { } while (0) | |
668 | #define sched_info_switch(t, next) do { } while (0) | |
52f17b6c | 669 | #endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */ |
1da177e4 LT |
670 | |
671 | /* | |
672 | * Adding/removing a task to/from a priority array: | |
673 | */ | |
70b97a7f | 674 | static void dequeue_task(struct task_struct *p, struct prio_array *array) |
1da177e4 LT |
675 | { |
676 | array->nr_active--; | |
677 | list_del(&p->run_list); | |
678 | if (list_empty(array->queue + p->prio)) | |
679 | __clear_bit(p->prio, array->bitmap); | |
680 | } | |
681 | ||
70b97a7f | 682 | static void enqueue_task(struct task_struct *p, struct prio_array *array) |
1da177e4 LT |
683 | { |
684 | sched_info_queued(p); | |
685 | list_add_tail(&p->run_list, array->queue + p->prio); | |
686 | __set_bit(p->prio, array->bitmap); | |
687 | array->nr_active++; | |
688 | p->array = array; | |
689 | } | |
690 | ||
691 | /* | |
692 | * Put task to the end of the run list without the overhead of dequeue | |
693 | * followed by enqueue. | |
694 | */ | |
70b97a7f | 695 | static void requeue_task(struct task_struct *p, struct prio_array *array) |
1da177e4 LT |
696 | { |
697 | list_move_tail(&p->run_list, array->queue + p->prio); | |
698 | } | |
699 | ||
70b97a7f IM |
700 | static inline void |
701 | enqueue_task_head(struct task_struct *p, struct prio_array *array) | |
1da177e4 LT |
702 | { |
703 | list_add(&p->run_list, array->queue + p->prio); | |
704 | __set_bit(p->prio, array->bitmap); | |
705 | array->nr_active++; | |
706 | p->array = array; | |
707 | } | |
708 | ||
709 | /* | |
b29739f9 | 710 | * __normal_prio - return the priority that is based on the static |
1da177e4 LT |
711 | * priority but is modified by bonuses/penalties. |
712 | * | |
713 | * We scale the actual sleep average [0 .... MAX_SLEEP_AVG] | |
714 | * into the -5 ... 0 ... +5 bonus/penalty range. | |
715 | * | |
716 | * We use 25% of the full 0...39 priority range so that: | |
717 | * | |
718 | * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs. | |
719 | * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks. | |
720 | * | |
721 | * Both properties are important to certain workloads. | |
722 | */ | |
b29739f9 | 723 | |
36c8b586 | 724 | static inline int __normal_prio(struct task_struct *p) |
1da177e4 LT |
725 | { |
726 | int bonus, prio; | |
727 | ||
1da177e4 LT |
728 | bonus = CURRENT_BONUS(p) - MAX_BONUS / 2; |
729 | ||
730 | prio = p->static_prio - bonus; | |
731 | if (prio < MAX_RT_PRIO) | |
732 | prio = MAX_RT_PRIO; | |
733 | if (prio > MAX_PRIO-1) | |
734 | prio = MAX_PRIO-1; | |
735 | return prio; | |
736 | } | |
737 | ||
2dd73a4f PW |
738 | /* |
739 | * To aid in avoiding the subversion of "niceness" due to uneven distribution | |
740 | * of tasks with abnormal "nice" values across CPUs the contribution that | |
741 | * each task makes to its run queue's load is weighted according to its | |
742 | * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a | |
743 | * scaled version of the new time slice allocation that they receive on time | |
744 | * slice expiry etc. | |
745 | */ | |
746 | ||
747 | /* | |
748 | * Assume: static_prio_timeslice(NICE_TO_PRIO(0)) == DEF_TIMESLICE | |
749 | * If static_prio_timeslice() is ever changed to break this assumption then | |
750 | * this code will need modification | |
751 | */ | |
752 | #define TIME_SLICE_NICE_ZERO DEF_TIMESLICE | |
753 | #define LOAD_WEIGHT(lp) \ | |
754 | (((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO) | |
755 | #define PRIO_TO_LOAD_WEIGHT(prio) \ | |
756 | LOAD_WEIGHT(static_prio_timeslice(prio)) | |
757 | #define RTPRIO_TO_LOAD_WEIGHT(rp) \ | |
758 | (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp)) | |
759 | ||
36c8b586 | 760 | static void set_load_weight(struct task_struct *p) |
2dd73a4f | 761 | { |
b29739f9 | 762 | if (has_rt_policy(p)) { |
2dd73a4f PW |
763 | #ifdef CONFIG_SMP |
764 | if (p == task_rq(p)->migration_thread) | |
765 | /* | |
766 | * The migration thread does the actual balancing. | |
767 | * Giving its load any weight will skew balancing | |
768 | * adversely. | |
769 | */ | |
770 | p->load_weight = 0; | |
771 | else | |
772 | #endif | |
773 | p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority); | |
774 | } else | |
775 | p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio); | |
776 | } | |
777 | ||
36c8b586 | 778 | static inline void |
70b97a7f | 779 | inc_raw_weighted_load(struct rq *rq, const struct task_struct *p) |
2dd73a4f PW |
780 | { |
781 | rq->raw_weighted_load += p->load_weight; | |
782 | } | |
783 | ||
36c8b586 | 784 | static inline void |
70b97a7f | 785 | dec_raw_weighted_load(struct rq *rq, const struct task_struct *p) |
2dd73a4f PW |
786 | { |
787 | rq->raw_weighted_load -= p->load_weight; | |
788 | } | |
789 | ||
70b97a7f | 790 | static inline void inc_nr_running(struct task_struct *p, struct rq *rq) |
2dd73a4f PW |
791 | { |
792 | rq->nr_running++; | |
793 | inc_raw_weighted_load(rq, p); | |
794 | } | |
795 | ||
70b97a7f | 796 | static inline void dec_nr_running(struct task_struct *p, struct rq *rq) |
2dd73a4f PW |
797 | { |
798 | rq->nr_running--; | |
799 | dec_raw_weighted_load(rq, p); | |
800 | } | |
801 | ||
b29739f9 IM |
802 | /* |
803 | * Calculate the expected normal priority: i.e. priority | |
804 | * without taking RT-inheritance into account. Might be | |
805 | * boosted by interactivity modifiers. Changes upon fork, | |
806 | * setprio syscalls, and whenever the interactivity | |
807 | * estimator recalculates. | |
808 | */ | |
36c8b586 | 809 | static inline int normal_prio(struct task_struct *p) |
b29739f9 IM |
810 | { |
811 | int prio; | |
812 | ||
813 | if (has_rt_policy(p)) | |
814 | prio = MAX_RT_PRIO-1 - p->rt_priority; | |
815 | else | |
816 | prio = __normal_prio(p); | |
817 | return prio; | |
818 | } | |
819 | ||
820 | /* | |
821 | * Calculate the current priority, i.e. the priority | |
822 | * taken into account by the scheduler. This value might | |
823 | * be boosted by RT tasks, or might be boosted by | |
824 | * interactivity modifiers. Will be RT if the task got | |
825 | * RT-boosted. If not then it returns p->normal_prio. | |
826 | */ | |
36c8b586 | 827 | static int effective_prio(struct task_struct *p) |
b29739f9 IM |
828 | { |
829 | p->normal_prio = normal_prio(p); | |
830 | /* | |
831 | * If we are RT tasks or we were boosted to RT priority, | |
832 | * keep the priority unchanged. Otherwise, update priority | |
833 | * to the normal priority: | |
834 | */ | |
835 | if (!rt_prio(p->prio)) | |
836 | return p->normal_prio; | |
837 | return p->prio; | |
838 | } | |
839 | ||
1da177e4 LT |
840 | /* |
841 | * __activate_task - move a task to the runqueue. | |
842 | */ | |
70b97a7f | 843 | static void __activate_task(struct task_struct *p, struct rq *rq) |
1da177e4 | 844 | { |
70b97a7f | 845 | struct prio_array *target = rq->active; |
d425b274 | 846 | |
f1adad78 | 847 | if (batch_task(p)) |
d425b274 CK |
848 | target = rq->expired; |
849 | enqueue_task(p, target); | |
2dd73a4f | 850 | inc_nr_running(p, rq); |
1da177e4 LT |
851 | } |
852 | ||
853 | /* | |
854 | * __activate_idle_task - move idle task to the _front_ of runqueue. | |
855 | */ | |
70b97a7f | 856 | static inline void __activate_idle_task(struct task_struct *p, struct rq *rq) |
1da177e4 LT |
857 | { |
858 | enqueue_task_head(p, rq->active); | |
2dd73a4f | 859 | inc_nr_running(p, rq); |
1da177e4 LT |
860 | } |
861 | ||
b29739f9 IM |
862 | /* |
863 | * Recalculate p->normal_prio and p->prio after having slept, | |
864 | * updating the sleep-average too: | |
865 | */ | |
36c8b586 | 866 | static int recalc_task_prio(struct task_struct *p, unsigned long long now) |
1da177e4 LT |
867 | { |
868 | /* Caller must always ensure 'now >= p->timestamp' */ | |
72d2854d | 869 | unsigned long sleep_time = now - p->timestamp; |
1da177e4 | 870 | |
d425b274 | 871 | if (batch_task(p)) |
b0a9499c | 872 | sleep_time = 0; |
1da177e4 LT |
873 | |
874 | if (likely(sleep_time > 0)) { | |
875 | /* | |
72d2854d CK |
876 | * This ceiling is set to the lowest priority that would allow |
877 | * a task to be reinserted into the active array on timeslice | |
878 | * completion. | |
1da177e4 | 879 | */ |
72d2854d | 880 | unsigned long ceiling = INTERACTIVE_SLEEP(p); |
e72ff0bb | 881 | |
72d2854d CK |
882 | if (p->mm && sleep_time > ceiling && p->sleep_avg < ceiling) { |
883 | /* | |
884 | * Prevents user tasks from achieving best priority | |
885 | * with one single large enough sleep. | |
886 | */ | |
887 | p->sleep_avg = ceiling; | |
888 | /* | |
889 | * Using INTERACTIVE_SLEEP() as a ceiling places a | |
890 | * nice(0) task 1ms sleep away from promotion, and | |
891 | * gives it 700ms to round-robin with no chance of | |
892 | * being demoted. This is more than generous, so | |
893 | * mark this sleep as non-interactive to prevent the | |
894 | * on-runqueue bonus logic from intervening should | |
895 | * this task not receive cpu immediately. | |
896 | */ | |
897 | p->sleep_type = SLEEP_NONINTERACTIVE; | |
1da177e4 | 898 | } else { |
1da177e4 LT |
899 | /* |
900 | * Tasks waking from uninterruptible sleep are | |
901 | * limited in their sleep_avg rise as they | |
902 | * are likely to be waiting on I/O | |
903 | */ | |
3dee386e | 904 | if (p->sleep_type == SLEEP_NONINTERACTIVE && p->mm) { |
72d2854d | 905 | if (p->sleep_avg >= ceiling) |
1da177e4 LT |
906 | sleep_time = 0; |
907 | else if (p->sleep_avg + sleep_time >= | |
72d2854d CK |
908 | ceiling) { |
909 | p->sleep_avg = ceiling; | |
910 | sleep_time = 0; | |
1da177e4 LT |
911 | } |
912 | } | |
913 | ||
914 | /* | |
915 | * This code gives a bonus to interactive tasks. | |
916 | * | |
917 | * The boost works by updating the 'average sleep time' | |
918 | * value here, based on ->timestamp. The more time a | |
919 | * task spends sleeping, the higher the average gets - | |
920 | * and the higher the priority boost gets as well. | |
921 | */ | |
922 | p->sleep_avg += sleep_time; | |
923 | ||
1da177e4 | 924 | } |
72d2854d CK |
925 | if (p->sleep_avg > NS_MAX_SLEEP_AVG) |
926 | p->sleep_avg = NS_MAX_SLEEP_AVG; | |
1da177e4 LT |
927 | } |
928 | ||
a3464a10 | 929 | return effective_prio(p); |
1da177e4 LT |
930 | } |
931 | ||
932 | /* | |
933 | * activate_task - move a task to the runqueue and do priority recalculation | |
934 | * | |
935 | * Update all the scheduling statistics stuff. (sleep average | |
936 | * calculation, priority modifiers, etc.) | |
937 | */ | |
70b97a7f | 938 | static void activate_task(struct task_struct *p, struct rq *rq, int local) |
1da177e4 LT |
939 | { |
940 | unsigned long long now; | |
941 | ||
942 | now = sched_clock(); | |
943 | #ifdef CONFIG_SMP | |
944 | if (!local) { | |
945 | /* Compensate for drifting sched_clock */ | |
70b97a7f | 946 | struct rq *this_rq = this_rq(); |
1da177e4 LT |
947 | now = (now - this_rq->timestamp_last_tick) |
948 | + rq->timestamp_last_tick; | |
949 | } | |
950 | #endif | |
951 | ||
ece8a684 IM |
952 | /* |
953 | * Sleep time is in units of nanosecs, so shift by 20 to get a | |
954 | * milliseconds-range estimation of the amount of time that the task | |
955 | * spent sleeping: | |
956 | */ | |
957 | if (unlikely(prof_on == SLEEP_PROFILING)) { | |
958 | if (p->state == TASK_UNINTERRUPTIBLE) | |
959 | profile_hits(SLEEP_PROFILING, (void *)get_wchan(p), | |
960 | (now - p->timestamp) >> 20); | |
961 | } | |
962 | ||
a47ab937 KC |
963 | if (!rt_task(p)) |
964 | p->prio = recalc_task_prio(p, now); | |
1da177e4 LT |
965 | |
966 | /* | |
967 | * This checks to make sure it's not an uninterruptible task | |
968 | * that is now waking up. | |
969 | */ | |
3dee386e | 970 | if (p->sleep_type == SLEEP_NORMAL) { |
1da177e4 LT |
971 | /* |
972 | * Tasks which were woken up by interrupts (ie. hw events) | |
973 | * are most likely of interactive nature. So we give them | |
974 | * the credit of extending their sleep time to the period | |
975 | * of time they spend on the runqueue, waiting for execution | |
976 | * on a CPU, first time around: | |
977 | */ | |
978 | if (in_interrupt()) | |
3dee386e | 979 | p->sleep_type = SLEEP_INTERRUPTED; |
1da177e4 LT |
980 | else { |
981 | /* | |
982 | * Normal first-time wakeups get a credit too for | |
983 | * on-runqueue time, but it will be weighted down: | |
984 | */ | |
3dee386e | 985 | p->sleep_type = SLEEP_INTERACTIVE; |
1da177e4 LT |
986 | } |
987 | } | |
988 | p->timestamp = now; | |
989 | ||
990 | __activate_task(p, rq); | |
991 | } | |
992 | ||
993 | /* | |
994 | * deactivate_task - remove a task from the runqueue. | |
995 | */ | |
70b97a7f | 996 | static void deactivate_task(struct task_struct *p, struct rq *rq) |
1da177e4 | 997 | { |
2dd73a4f | 998 | dec_nr_running(p, rq); |
1da177e4 LT |
999 | dequeue_task(p, p->array); |
1000 | p->array = NULL; | |
1001 | } | |
1002 | ||
1003 | /* | |
1004 | * resched_task - mark a task 'to be rescheduled now'. | |
1005 | * | |
1006 | * On UP this means the setting of the need_resched flag, on SMP it | |
1007 | * might also involve a cross-CPU call to trigger the scheduler on | |
1008 | * the target CPU. | |
1009 | */ | |
1010 | #ifdef CONFIG_SMP | |
495ab9c0 AK |
1011 | |
1012 | #ifndef tsk_is_polling | |
1013 | #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG) | |
1014 | #endif | |
1015 | ||
36c8b586 | 1016 | static void resched_task(struct task_struct *p) |
1da177e4 | 1017 | { |
64c7c8f8 | 1018 | int cpu; |
1da177e4 LT |
1019 | |
1020 | assert_spin_locked(&task_rq(p)->lock); | |
1021 | ||
64c7c8f8 NP |
1022 | if (unlikely(test_tsk_thread_flag(p, TIF_NEED_RESCHED))) |
1023 | return; | |
1024 | ||
1025 | set_tsk_thread_flag(p, TIF_NEED_RESCHED); | |
1da177e4 | 1026 | |
64c7c8f8 NP |
1027 | cpu = task_cpu(p); |
1028 | if (cpu == smp_processor_id()) | |
1029 | return; | |
1030 | ||
495ab9c0 | 1031 | /* NEED_RESCHED must be visible before we test polling */ |
64c7c8f8 | 1032 | smp_mb(); |
495ab9c0 | 1033 | if (!tsk_is_polling(p)) |
64c7c8f8 | 1034 | smp_send_reschedule(cpu); |
1da177e4 LT |
1035 | } |
1036 | #else | |
36c8b586 | 1037 | static inline void resched_task(struct task_struct *p) |
1da177e4 | 1038 | { |
64c7c8f8 | 1039 | assert_spin_locked(&task_rq(p)->lock); |
1da177e4 LT |
1040 | set_tsk_need_resched(p); |
1041 | } | |
1042 | #endif | |
1043 | ||
1044 | /** | |
1045 | * task_curr - is this task currently executing on a CPU? | |
1046 | * @p: the task in question. | |
1047 | */ | |
36c8b586 | 1048 | inline int task_curr(const struct task_struct *p) |
1da177e4 LT |
1049 | { |
1050 | return cpu_curr(task_cpu(p)) == p; | |
1051 | } | |
1052 | ||
2dd73a4f PW |
1053 | /* Used instead of source_load when we know the type == 0 */ |
1054 | unsigned long weighted_cpuload(const int cpu) | |
1055 | { | |
1056 | return cpu_rq(cpu)->raw_weighted_load; | |
1057 | } | |
1058 | ||
1da177e4 | 1059 | #ifdef CONFIG_SMP |
70b97a7f | 1060 | struct migration_req { |
1da177e4 | 1061 | struct list_head list; |
1da177e4 | 1062 | |
36c8b586 | 1063 | struct task_struct *task; |
1da177e4 LT |
1064 | int dest_cpu; |
1065 | ||
1da177e4 | 1066 | struct completion done; |
70b97a7f | 1067 | }; |
1da177e4 LT |
1068 | |
1069 | /* | |
1070 | * The task's runqueue lock must be held. | |
1071 | * Returns true if you have to wait for migration thread. | |
1072 | */ | |
36c8b586 | 1073 | static int |
70b97a7f | 1074 | migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req) |
1da177e4 | 1075 | { |
70b97a7f | 1076 | struct rq *rq = task_rq(p); |
1da177e4 LT |
1077 | |
1078 | /* | |
1079 | * If the task is not on a runqueue (and not running), then | |
1080 | * it is sufficient to simply update the task's cpu field. | |
1081 | */ | |
1082 | if (!p->array && !task_running(rq, p)) { | |
1083 | set_task_cpu(p, dest_cpu); | |
1084 | return 0; | |
1085 | } | |
1086 | ||
1087 | init_completion(&req->done); | |
1da177e4 LT |
1088 | req->task = p; |
1089 | req->dest_cpu = dest_cpu; | |
1090 | list_add(&req->list, &rq->migration_queue); | |
48f24c4d | 1091 | |
1da177e4 LT |
1092 | return 1; |
1093 | } | |
1094 | ||
1095 | /* | |
1096 | * wait_task_inactive - wait for a thread to unschedule. | |
1097 | * | |
1098 | * The caller must ensure that the task *will* unschedule sometime soon, | |
1099 | * else this function might spin for a *long* time. This function can't | |
1100 | * be called with interrupts off, or it may introduce deadlock with | |
1101 | * smp_call_function() if an IPI is sent by the same process we are | |
1102 | * waiting to become inactive. | |
1103 | */ | |
36c8b586 | 1104 | void wait_task_inactive(struct task_struct *p) |
1da177e4 LT |
1105 | { |
1106 | unsigned long flags; | |
70b97a7f | 1107 | struct rq *rq; |
1da177e4 LT |
1108 | int preempted; |
1109 | ||
1110 | repeat: | |
1111 | rq = task_rq_lock(p, &flags); | |
1112 | /* Must be off runqueue entirely, not preempted. */ | |
1113 | if (unlikely(p->array || task_running(rq, p))) { | |
1114 | /* If it's preempted, we yield. It could be a while. */ | |
1115 | preempted = !task_running(rq, p); | |
1116 | task_rq_unlock(rq, &flags); | |
1117 | cpu_relax(); | |
1118 | if (preempted) | |
1119 | yield(); | |
1120 | goto repeat; | |
1121 | } | |
1122 | task_rq_unlock(rq, &flags); | |
1123 | } | |
1124 | ||
1125 | /*** | |
1126 | * kick_process - kick a running thread to enter/exit the kernel | |
1127 | * @p: the to-be-kicked thread | |
1128 | * | |
1129 | * Cause a process which is running on another CPU to enter | |
1130 | * kernel-mode, without any delay. (to get signals handled.) | |
1131 | * | |
1132 | * NOTE: this function doesnt have to take the runqueue lock, | |
1133 | * because all it wants to ensure is that the remote task enters | |
1134 | * the kernel. If the IPI races and the task has been migrated | |
1135 | * to another CPU then no harm is done and the purpose has been | |
1136 | * achieved as well. | |
1137 | */ | |
36c8b586 | 1138 | void kick_process(struct task_struct *p) |
1da177e4 LT |
1139 | { |
1140 | int cpu; | |
1141 | ||
1142 | preempt_disable(); | |
1143 | cpu = task_cpu(p); | |
1144 | if ((cpu != smp_processor_id()) && task_curr(p)) | |
1145 | smp_send_reschedule(cpu); | |
1146 | preempt_enable(); | |
1147 | } | |
1148 | ||
1149 | /* | |
2dd73a4f PW |
1150 | * Return a low guess at the load of a migration-source cpu weighted |
1151 | * according to the scheduling class and "nice" value. | |
1da177e4 LT |
1152 | * |
1153 | * We want to under-estimate the load of migration sources, to | |
1154 | * balance conservatively. | |
1155 | */ | |
a2000572 | 1156 | static inline unsigned long source_load(int cpu, int type) |
1da177e4 | 1157 | { |
70b97a7f | 1158 | struct rq *rq = cpu_rq(cpu); |
2dd73a4f | 1159 | |
3b0bd9bc | 1160 | if (type == 0) |
2dd73a4f | 1161 | return rq->raw_weighted_load; |
b910472d | 1162 | |
2dd73a4f | 1163 | return min(rq->cpu_load[type-1], rq->raw_weighted_load); |
1da177e4 LT |
1164 | } |
1165 | ||
1166 | /* | |
2dd73a4f PW |
1167 | * Return a high guess at the load of a migration-target cpu weighted |
1168 | * according to the scheduling class and "nice" value. | |
1da177e4 | 1169 | */ |
a2000572 | 1170 | static inline unsigned long target_load(int cpu, int type) |
1da177e4 | 1171 | { |
70b97a7f | 1172 | struct rq *rq = cpu_rq(cpu); |
2dd73a4f | 1173 | |
7897986b | 1174 | if (type == 0) |
2dd73a4f | 1175 | return rq->raw_weighted_load; |
3b0bd9bc | 1176 | |
2dd73a4f PW |
1177 | return max(rq->cpu_load[type-1], rq->raw_weighted_load); |
1178 | } | |
1179 | ||
1180 | /* | |
1181 | * Return the average load per task on the cpu's run queue | |
1182 | */ | |
1183 | static inline unsigned long cpu_avg_load_per_task(int cpu) | |
1184 | { | |
70b97a7f | 1185 | struct rq *rq = cpu_rq(cpu); |
2dd73a4f PW |
1186 | unsigned long n = rq->nr_running; |
1187 | ||
48f24c4d | 1188 | return n ? rq->raw_weighted_load / n : SCHED_LOAD_SCALE; |
1da177e4 LT |
1189 | } |
1190 | ||
147cbb4b NP |
1191 | /* |
1192 | * find_idlest_group finds and returns the least busy CPU group within the | |
1193 | * domain. | |
1194 | */ | |
1195 | static struct sched_group * | |
1196 | find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) | |
1197 | { | |
1198 | struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups; | |
1199 | unsigned long min_load = ULONG_MAX, this_load = 0; | |
1200 | int load_idx = sd->forkexec_idx; | |
1201 | int imbalance = 100 + (sd->imbalance_pct-100)/2; | |
1202 | ||
1203 | do { | |
1204 | unsigned long load, avg_load; | |
1205 | int local_group; | |
1206 | int i; | |
1207 | ||
da5a5522 BD |
1208 | /* Skip over this group if it has no CPUs allowed */ |
1209 | if (!cpus_intersects(group->cpumask, p->cpus_allowed)) | |
1210 | goto nextgroup; | |
1211 | ||
147cbb4b | 1212 | local_group = cpu_isset(this_cpu, group->cpumask); |
147cbb4b NP |
1213 | |
1214 | /* Tally up the load of all CPUs in the group */ | |
1215 | avg_load = 0; | |
1216 | ||
1217 | for_each_cpu_mask(i, group->cpumask) { | |
1218 | /* Bias balancing toward cpus of our domain */ | |
1219 | if (local_group) | |
1220 | load = source_load(i, load_idx); | |
1221 | else | |
1222 | load = target_load(i, load_idx); | |
1223 | ||
1224 | avg_load += load; | |
1225 | } | |
1226 | ||
1227 | /* Adjust by relative CPU power of the group */ | |
1228 | avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power; | |
1229 | ||
1230 | if (local_group) { | |
1231 | this_load = avg_load; | |
1232 | this = group; | |
1233 | } else if (avg_load < min_load) { | |
1234 | min_load = avg_load; | |
1235 | idlest = group; | |
1236 | } | |
da5a5522 | 1237 | nextgroup: |
147cbb4b NP |
1238 | group = group->next; |
1239 | } while (group != sd->groups); | |
1240 | ||
1241 | if (!idlest || 100*this_load < imbalance*min_load) | |
1242 | return NULL; | |
1243 | return idlest; | |
1244 | } | |
1245 | ||
1246 | /* | |
0feaece9 | 1247 | * find_idlest_cpu - find the idlest cpu among the cpus in group. |
147cbb4b | 1248 | */ |
95cdf3b7 IM |
1249 | static int |
1250 | find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) | |
147cbb4b | 1251 | { |
da5a5522 | 1252 | cpumask_t tmp; |
147cbb4b NP |
1253 | unsigned long load, min_load = ULONG_MAX; |
1254 | int idlest = -1; | |
1255 | int i; | |
1256 | ||
da5a5522 BD |
1257 | /* Traverse only the allowed CPUs */ |
1258 | cpus_and(tmp, group->cpumask, p->cpus_allowed); | |
1259 | ||
1260 | for_each_cpu_mask(i, tmp) { | |
2dd73a4f | 1261 | load = weighted_cpuload(i); |
147cbb4b NP |
1262 | |
1263 | if (load < min_load || (load == min_load && i == this_cpu)) { | |
1264 | min_load = load; | |
1265 | idlest = i; | |
1266 | } | |
1267 | } | |
1268 | ||
1269 | return idlest; | |
1270 | } | |
1271 | ||
476d139c NP |
1272 | /* |
1273 | * sched_balance_self: balance the current task (running on cpu) in domains | |
1274 | * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and | |
1275 | * SD_BALANCE_EXEC. | |
1276 | * | |
1277 | * Balance, ie. select the least loaded group. | |
1278 | * | |
1279 | * Returns the target CPU number, or the same CPU if no balancing is needed. | |
1280 | * | |
1281 | * preempt must be disabled. | |
1282 | */ | |
1283 | static int sched_balance_self(int cpu, int flag) | |
1284 | { | |
1285 | struct task_struct *t = current; | |
1286 | struct sched_domain *tmp, *sd = NULL; | |
147cbb4b | 1287 | |
c96d145e | 1288 | for_each_domain(cpu, tmp) { |
5c45bf27 SS |
1289 | /* |
1290 | * If power savings logic is enabled for a domain, stop there. | |
1291 | */ | |
1292 | if (tmp->flags & SD_POWERSAVINGS_BALANCE) | |
1293 | break; | |
476d139c NP |
1294 | if (tmp->flags & flag) |
1295 | sd = tmp; | |
c96d145e | 1296 | } |
476d139c NP |
1297 | |
1298 | while (sd) { | |
1299 | cpumask_t span; | |
1300 | struct sched_group *group; | |
1a848870 SS |
1301 | int new_cpu, weight; |
1302 | ||
1303 | if (!(sd->flags & flag)) { | |
1304 | sd = sd->child; | |
1305 | continue; | |
1306 | } | |
476d139c NP |
1307 | |
1308 | span = sd->span; | |
1309 | group = find_idlest_group(sd, t, cpu); | |
1a848870 SS |
1310 | if (!group) { |
1311 | sd = sd->child; | |
1312 | continue; | |
1313 | } | |
476d139c | 1314 | |
da5a5522 | 1315 | new_cpu = find_idlest_cpu(group, t, cpu); |
1a848870 SS |
1316 | if (new_cpu == -1 || new_cpu == cpu) { |
1317 | /* Now try balancing at a lower domain level of cpu */ | |
1318 | sd = sd->child; | |
1319 | continue; | |
1320 | } | |
476d139c | 1321 | |
1a848870 | 1322 | /* Now try balancing at a lower domain level of new_cpu */ |
476d139c | 1323 | cpu = new_cpu; |
476d139c NP |
1324 | sd = NULL; |
1325 | weight = cpus_weight(span); | |
1326 | for_each_domain(cpu, tmp) { | |
1327 | if (weight <= cpus_weight(tmp->span)) | |
1328 | break; | |
1329 | if (tmp->flags & flag) | |
1330 | sd = tmp; | |
1331 | } | |
1332 | /* while loop will break here if sd == NULL */ | |
1333 | } | |
1334 | ||
1335 | return cpu; | |
1336 | } | |
1337 | ||
1338 | #endif /* CONFIG_SMP */ | |
1da177e4 LT |
1339 | |
1340 | /* | |
1341 | * wake_idle() will wake a task on an idle cpu if task->cpu is | |
1342 | * not idle and an idle cpu is available. The span of cpus to | |
1343 | * search starts with cpus closest then further out as needed, | |
1344 | * so we always favor a closer, idle cpu. | |
1345 | * | |
1346 | * Returns the CPU we should wake onto. | |
1347 | */ | |
1348 | #if defined(ARCH_HAS_SCHED_WAKE_IDLE) | |
36c8b586 | 1349 | static int wake_idle(int cpu, struct task_struct *p) |
1da177e4 LT |
1350 | { |
1351 | cpumask_t tmp; | |
1352 | struct sched_domain *sd; | |
1353 | int i; | |
1354 | ||
1355 | if (idle_cpu(cpu)) | |
1356 | return cpu; | |
1357 | ||
1358 | for_each_domain(cpu, sd) { | |
1359 | if (sd->flags & SD_WAKE_IDLE) { | |
e0f364f4 | 1360 | cpus_and(tmp, sd->span, p->cpus_allowed); |
1da177e4 LT |
1361 | for_each_cpu_mask(i, tmp) { |
1362 | if (idle_cpu(i)) | |
1363 | return i; | |
1364 | } | |
1365 | } | |
e0f364f4 NP |
1366 | else |
1367 | break; | |
1da177e4 LT |
1368 | } |
1369 | return cpu; | |
1370 | } | |
1371 | #else | |
36c8b586 | 1372 | static inline int wake_idle(int cpu, struct task_struct *p) |
1da177e4 LT |
1373 | { |
1374 | return cpu; | |
1375 | } | |
1376 | #endif | |
1377 | ||
1378 | /*** | |
1379 | * try_to_wake_up - wake up a thread | |
1380 | * @p: the to-be-woken-up thread | |
1381 | * @state: the mask of task states that can be woken | |
1382 | * @sync: do a synchronous wakeup? | |
1383 | * | |
1384 | * Put it on the run-queue if it's not already there. The "current" | |
1385 | * thread is always on the run-queue (except when the actual | |
1386 | * re-schedule is in progress), and as such you're allowed to do | |
1387 | * the simpler "current->state = TASK_RUNNING" to mark yourself | |
1388 | * runnable without the overhead of this. | |
1389 | * | |
1390 | * returns failure only if the task is already active. | |
1391 | */ | |
36c8b586 | 1392 | static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) |
1da177e4 LT |
1393 | { |
1394 | int cpu, this_cpu, success = 0; | |
1395 | unsigned long flags; | |
1396 | long old_state; | |
70b97a7f | 1397 | struct rq *rq; |
1da177e4 | 1398 | #ifdef CONFIG_SMP |
7897986b | 1399 | struct sched_domain *sd, *this_sd = NULL; |
70b97a7f | 1400 | unsigned long load, this_load; |
1da177e4 LT |
1401 | int new_cpu; |
1402 | #endif | |
1403 | ||
1404 | rq = task_rq_lock(p, &flags); | |
1405 | old_state = p->state; | |
1406 | if (!(old_state & state)) | |
1407 | goto out; | |
1408 | ||
1409 | if (p->array) | |
1410 | goto out_running; | |
1411 | ||
1412 | cpu = task_cpu(p); | |
1413 | this_cpu = smp_processor_id(); | |
1414 | ||
1415 | #ifdef CONFIG_SMP | |
1416 | if (unlikely(task_running(rq, p))) | |
1417 | goto out_activate; | |
1418 | ||
7897986b NP |
1419 | new_cpu = cpu; |
1420 | ||
1da177e4 LT |
1421 | schedstat_inc(rq, ttwu_cnt); |
1422 | if (cpu == this_cpu) { | |
1423 | schedstat_inc(rq, ttwu_local); | |
7897986b NP |
1424 | goto out_set_cpu; |
1425 | } | |
1426 | ||
1427 | for_each_domain(this_cpu, sd) { | |
1428 | if (cpu_isset(cpu, sd->span)) { | |
1429 | schedstat_inc(sd, ttwu_wake_remote); | |
1430 | this_sd = sd; | |
1431 | break; | |
1da177e4 LT |
1432 | } |
1433 | } | |
1da177e4 | 1434 | |
7897986b | 1435 | if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed))) |
1da177e4 LT |
1436 | goto out_set_cpu; |
1437 | ||
1da177e4 | 1438 | /* |
7897986b | 1439 | * Check for affine wakeup and passive balancing possibilities. |
1da177e4 | 1440 | */ |
7897986b NP |
1441 | if (this_sd) { |
1442 | int idx = this_sd->wake_idx; | |
1443 | unsigned int imbalance; | |
1da177e4 | 1444 | |
a3f21bce NP |
1445 | imbalance = 100 + (this_sd->imbalance_pct - 100) / 2; |
1446 | ||
7897986b NP |
1447 | load = source_load(cpu, idx); |
1448 | this_load = target_load(this_cpu, idx); | |
1da177e4 | 1449 | |
7897986b NP |
1450 | new_cpu = this_cpu; /* Wake to this CPU if we can */ |
1451 | ||
a3f21bce NP |
1452 | if (this_sd->flags & SD_WAKE_AFFINE) { |
1453 | unsigned long tl = this_load; | |
2dd73a4f PW |
1454 | unsigned long tl_per_task = cpu_avg_load_per_task(this_cpu); |
1455 | ||
1da177e4 | 1456 | /* |
a3f21bce NP |
1457 | * If sync wakeup then subtract the (maximum possible) |
1458 | * effect of the currently running task from the load | |
1459 | * of the current CPU: | |
1da177e4 | 1460 | */ |
a3f21bce | 1461 | if (sync) |
2dd73a4f | 1462 | tl -= current->load_weight; |
a3f21bce NP |
1463 | |
1464 | if ((tl <= load && | |
2dd73a4f PW |
1465 | tl + target_load(cpu, idx) <= tl_per_task) || |
1466 | 100*(tl + p->load_weight) <= imbalance*load) { | |
a3f21bce NP |
1467 | /* |
1468 | * This domain has SD_WAKE_AFFINE and | |
1469 | * p is cache cold in this domain, and | |
1470 | * there is no bad imbalance. | |
1471 | */ | |
1472 | schedstat_inc(this_sd, ttwu_move_affine); | |
1473 | goto out_set_cpu; | |
1474 | } | |
1475 | } | |
1476 | ||
1477 | /* | |
1478 | * Start passive balancing when half the imbalance_pct | |
1479 | * limit is reached. | |
1480 | */ | |
1481 | if (this_sd->flags & SD_WAKE_BALANCE) { | |
1482 | if (imbalance*this_load <= 100*load) { | |
1483 | schedstat_inc(this_sd, ttwu_move_balance); | |
1484 | goto out_set_cpu; | |
1485 | } | |
1da177e4 LT |
1486 | } |
1487 | } | |
1488 | ||
1489 | new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */ | |
1490 | out_set_cpu: | |
1491 | new_cpu = wake_idle(new_cpu, p); | |
1492 | if (new_cpu != cpu) { | |
1493 | set_task_cpu(p, new_cpu); | |
1494 | task_rq_unlock(rq, &flags); | |
1495 | /* might preempt at this point */ | |
1496 | rq = task_rq_lock(p, &flags); | |
1497 | old_state = p->state; | |
1498 | if (!(old_state & state)) | |
1499 | goto out; | |
1500 | if (p->array) | |
1501 | goto out_running; | |
1502 | ||
1503 | this_cpu = smp_processor_id(); | |
1504 | cpu = task_cpu(p); | |
1505 | } | |
1506 | ||
1507 | out_activate: | |
1508 | #endif /* CONFIG_SMP */ | |
1509 | if (old_state == TASK_UNINTERRUPTIBLE) { | |
1510 | rq->nr_uninterruptible--; | |
1511 | /* | |
1512 | * Tasks on involuntary sleep don't earn | |
1513 | * sleep_avg beyond just interactive state. | |
1514 | */ | |
3dee386e | 1515 | p->sleep_type = SLEEP_NONINTERACTIVE; |
e7c38cb4 | 1516 | } else |
1da177e4 | 1517 | |
d79fc0fc IM |
1518 | /* |
1519 | * Tasks that have marked their sleep as noninteractive get | |
e7c38cb4 CK |
1520 | * woken up with their sleep average not weighted in an |
1521 | * interactive way. | |
d79fc0fc | 1522 | */ |
e7c38cb4 CK |
1523 | if (old_state & TASK_NONINTERACTIVE) |
1524 | p->sleep_type = SLEEP_NONINTERACTIVE; | |
1525 | ||
1526 | ||
1527 | activate_task(p, rq, cpu == this_cpu); | |
1da177e4 LT |
1528 | /* |
1529 | * Sync wakeups (i.e. those types of wakeups where the waker | |
1530 | * has indicated that it will leave the CPU in short order) | |
1531 | * don't trigger a preemption, if the woken up task will run on | |
1532 | * this cpu. (in this case the 'I will reschedule' promise of | |
1533 | * the waker guarantees that the freshly woken up task is going | |
1534 | * to be considered on this CPU.) | |
1535 | */ | |
1da177e4 LT |
1536 | if (!sync || cpu != this_cpu) { |
1537 | if (TASK_PREEMPTS_CURR(p, rq)) | |
1538 | resched_task(rq->curr); | |
1539 | } | |
1540 | success = 1; | |
1541 | ||
1542 | out_running: | |
1543 | p->state = TASK_RUNNING; | |
1544 | out: | |
1545 | task_rq_unlock(rq, &flags); | |
1546 | ||
1547 | return success; | |
1548 | } | |
1549 | ||
36c8b586 | 1550 | int fastcall wake_up_process(struct task_struct *p) |
1da177e4 LT |
1551 | { |
1552 | return try_to_wake_up(p, TASK_STOPPED | TASK_TRACED | | |
1553 | TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE, 0); | |
1554 | } | |
1da177e4 LT |
1555 | EXPORT_SYMBOL(wake_up_process); |
1556 | ||
36c8b586 | 1557 | int fastcall wake_up_state(struct task_struct *p, unsigned int state) |
1da177e4 LT |
1558 | { |
1559 | return try_to_wake_up(p, state, 0); | |
1560 | } | |
1561 | ||
1da177e4 LT |
1562 | /* |
1563 | * Perform scheduler related setup for a newly forked process p. | |
1564 | * p is forked by current. | |
1565 | */ | |
36c8b586 | 1566 | void fastcall sched_fork(struct task_struct *p, int clone_flags) |
1da177e4 | 1567 | { |
476d139c NP |
1568 | int cpu = get_cpu(); |
1569 | ||
1570 | #ifdef CONFIG_SMP | |
1571 | cpu = sched_balance_self(cpu, SD_BALANCE_FORK); | |
1572 | #endif | |
1573 | set_task_cpu(p, cpu); | |
1574 | ||
1da177e4 LT |
1575 | /* |
1576 | * We mark the process as running here, but have not actually | |
1577 | * inserted it onto the runqueue yet. This guarantees that | |
1578 | * nobody will actually run it, and a signal or other external | |
1579 | * event cannot wake it up and insert it on the runqueue either. | |
1580 | */ | |
1581 | p->state = TASK_RUNNING; | |
b29739f9 IM |
1582 | |
1583 | /* | |
1584 | * Make sure we do not leak PI boosting priority to the child: | |
1585 | */ | |
1586 | p->prio = current->normal_prio; | |
1587 | ||
1da177e4 LT |
1588 | INIT_LIST_HEAD(&p->run_list); |
1589 | p->array = NULL; | |
52f17b6c CS |
1590 | #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) |
1591 | if (unlikely(sched_info_on())) | |
1592 | memset(&p->sched_info, 0, sizeof(p->sched_info)); | |
1da177e4 | 1593 | #endif |
d6077cb8 | 1594 | #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) |
4866cde0 NP |
1595 | p->oncpu = 0; |
1596 | #endif | |
1da177e4 | 1597 | #ifdef CONFIG_PREEMPT |
4866cde0 | 1598 | /* Want to start with kernel preemption disabled. */ |
a1261f54 | 1599 | task_thread_info(p)->preempt_count = 1; |
1da177e4 LT |
1600 | #endif |
1601 | /* | |
1602 | * Share the timeslice between parent and child, thus the | |
1603 | * total amount of pending timeslices in the system doesn't change, | |
1604 | * resulting in more scheduling fairness. | |
1605 | */ | |
1606 | local_irq_disable(); | |
1607 | p->time_slice = (current->time_slice + 1) >> 1; | |
1608 | /* | |
1609 | * The remainder of the first timeslice might be recovered by | |
1610 | * the parent if the child exits early enough. | |
1611 | */ | |
1612 | p->first_time_slice = 1; | |
1613 | current->time_slice >>= 1; | |
1614 | p->timestamp = sched_clock(); | |
1615 | if (unlikely(!current->time_slice)) { | |
1616 | /* | |
1617 | * This case is rare, it happens when the parent has only | |
1618 | * a single jiffy left from its timeslice. Taking the | |
1619 | * runqueue lock is not a problem. | |
1620 | */ | |
1621 | current->time_slice = 1; | |
1da177e4 | 1622 | scheduler_tick(); |
476d139c NP |
1623 | } |
1624 | local_irq_enable(); | |
1625 | put_cpu(); | |
1da177e4 LT |
1626 | } |
1627 | ||
1628 | /* | |
1629 | * wake_up_new_task - wake up a newly created task for the first time. | |
1630 | * | |
1631 | * This function will do some initial scheduler statistics housekeeping | |
1632 | * that must be done for every newly created context, then puts the task | |
1633 | * on the runqueue and wakes it. | |
1634 | */ | |
36c8b586 | 1635 | void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) |
1da177e4 | 1636 | { |
70b97a7f | 1637 | struct rq *rq, *this_rq; |
1da177e4 LT |
1638 | unsigned long flags; |
1639 | int this_cpu, cpu; | |
1da177e4 LT |
1640 | |
1641 | rq = task_rq_lock(p, &flags); | |
147cbb4b | 1642 | BUG_ON(p->state != TASK_RUNNING); |
1da177e4 | 1643 | this_cpu = smp_processor_id(); |
147cbb4b | 1644 | cpu = task_cpu(p); |
1da177e4 | 1645 | |
1da177e4 LT |
1646 | /* |
1647 | * We decrease the sleep average of forking parents | |
1648 | * and children as well, to keep max-interactive tasks | |
1649 | * from forking tasks that are max-interactive. The parent | |
1650 | * (current) is done further down, under its lock. | |
1651 | */ | |
1652 | p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) * | |
1653 | CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); | |
1654 | ||
1655 | p->prio = effective_prio(p); | |
1656 | ||
1657 | if (likely(cpu == this_cpu)) { | |
1658 | if (!(clone_flags & CLONE_VM)) { | |
1659 | /* | |
1660 | * The VM isn't cloned, so we're in a good position to | |
1661 | * do child-runs-first in anticipation of an exec. This | |
1662 | * usually avoids a lot of COW overhead. | |
1663 | */ | |
1664 | if (unlikely(!current->array)) | |
1665 | __activate_task(p, rq); | |
1666 | else { | |
1667 | p->prio = current->prio; | |
b29739f9 | 1668 | p->normal_prio = current->normal_prio; |
1da177e4 LT |
1669 | list_add_tail(&p->run_list, ¤t->run_list); |
1670 | p->array = current->array; | |
1671 | p->array->nr_active++; | |
2dd73a4f | 1672 | inc_nr_running(p, rq); |
1da177e4 LT |
1673 | } |
1674 | set_need_resched(); | |
1675 | } else | |
1676 | /* Run child last */ | |
1677 | __activate_task(p, rq); | |
1678 | /* | |
1679 | * We skip the following code due to cpu == this_cpu | |
1680 | * | |
1681 | * task_rq_unlock(rq, &flags); | |
1682 | * this_rq = task_rq_lock(current, &flags); | |
1683 | */ | |
1684 | this_rq = rq; | |
1685 | } else { | |
1686 | this_rq = cpu_rq(this_cpu); | |
1687 | ||
1688 | /* | |
1689 | * Not the local CPU - must adjust timestamp. This should | |
1690 | * get optimised away in the !CONFIG_SMP case. | |
1691 | */ | |
1692 | p->timestamp = (p->timestamp - this_rq->timestamp_last_tick) | |
1693 | + rq->timestamp_last_tick; | |
1694 | __activate_task(p, rq); | |
1695 | if (TASK_PREEMPTS_CURR(p, rq)) | |
1696 | resched_task(rq->curr); | |
1697 | ||
1698 | /* | |
1699 | * Parent and child are on different CPUs, now get the | |
1700 | * parent runqueue to update the parent's ->sleep_avg: | |
1701 | */ | |
1702 | task_rq_unlock(rq, &flags); | |
1703 | this_rq = task_rq_lock(current, &flags); | |
1704 | } | |
1705 | current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) * | |
1706 | PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); | |
1707 | task_rq_unlock(this_rq, &flags); | |
1708 | } | |
1709 | ||
1710 | /* | |
1711 | * Potentially available exiting-child timeslices are | |
1712 | * retrieved here - this way the parent does not get | |
1713 | * penalized for creating too many threads. | |
1714 | * | |
1715 | * (this cannot be used to 'generate' timeslices | |
1716 | * artificially, because any timeslice recovered here | |
1717 | * was given away by the parent in the first place.) | |
1718 | */ | |
36c8b586 | 1719 | void fastcall sched_exit(struct task_struct *p) |
1da177e4 LT |
1720 | { |
1721 | unsigned long flags; | |
70b97a7f | 1722 | struct rq *rq; |
1da177e4 LT |
1723 | |
1724 | /* | |
1725 | * If the child was a (relative-) CPU hog then decrease | |
1726 | * the sleep_avg of the parent as well. | |
1727 | */ | |
1728 | rq = task_rq_lock(p->parent, &flags); | |
889dfafe | 1729 | if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) { |
1da177e4 LT |
1730 | p->parent->time_slice += p->time_slice; |
1731 | if (unlikely(p->parent->time_slice > task_timeslice(p))) | |
1732 | p->parent->time_slice = task_timeslice(p); | |
1733 | } | |
1734 | if (p->sleep_avg < p->parent->sleep_avg) | |
1735 | p->parent->sleep_avg = p->parent->sleep_avg / | |
1736 | (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg / | |
1737 | (EXIT_WEIGHT + 1); | |
1738 | task_rq_unlock(rq, &flags); | |
1739 | } | |
1740 | ||
4866cde0 NP |
1741 | /** |
1742 | * prepare_task_switch - prepare to switch tasks | |
1743 | * @rq: the runqueue preparing to switch | |
1744 | * @next: the task we are going to switch to. | |
1745 | * | |
1746 | * This is called with the rq lock held and interrupts off. It must | |
1747 | * be paired with a subsequent finish_task_switch after the context | |
1748 | * switch. | |
1749 | * | |
1750 | * prepare_task_switch sets up locking and calls architecture specific | |
1751 | * hooks. | |
1752 | */ | |
70b97a7f | 1753 | static inline void prepare_task_switch(struct rq *rq, struct task_struct *next) |
4866cde0 NP |
1754 | { |
1755 | prepare_lock_switch(rq, next); | |
1756 | prepare_arch_switch(next); | |
1757 | } | |
1758 | ||
1da177e4 LT |
1759 | /** |
1760 | * finish_task_switch - clean up after a task-switch | |
344babaa | 1761 | * @rq: runqueue associated with task-switch |
1da177e4 LT |
1762 | * @prev: the thread we just switched away from. |
1763 | * | |
4866cde0 NP |
1764 | * finish_task_switch must be called after the context switch, paired |
1765 | * with a prepare_task_switch call before the context switch. | |
1766 | * finish_task_switch will reconcile locking set up by prepare_task_switch, | |
1767 | * and do any other architecture-specific cleanup actions. | |
1da177e4 LT |
1768 | * |
1769 | * Note that we may have delayed dropping an mm in context_switch(). If | |
1770 | * so, we finish that here outside of the runqueue lock. (Doing it | |
1771 | * with the lock held can cause deadlocks; see schedule() for | |
1772 | * details.) | |
1773 | */ | |
70b97a7f | 1774 | static inline void finish_task_switch(struct rq *rq, struct task_struct *prev) |
1da177e4 LT |
1775 | __releases(rq->lock) |
1776 | { | |
1da177e4 | 1777 | struct mm_struct *mm = rq->prev_mm; |
55a101f8 | 1778 | long prev_state; |
1da177e4 LT |
1779 | |
1780 | rq->prev_mm = NULL; | |
1781 | ||
1782 | /* | |
1783 | * A task struct has one reference for the use as "current". | |
c394cc9f | 1784 | * If a task dies, then it sets TASK_DEAD in tsk->state and calls |
55a101f8 ON |
1785 | * schedule one last time. The schedule call will never return, and |
1786 | * the scheduled task must drop that reference. | |
c394cc9f | 1787 | * The test for TASK_DEAD must occur while the runqueue locks are |
1da177e4 LT |
1788 | * still held, otherwise prev could be scheduled on another cpu, die |
1789 | * there before we look at prev->state, and then the reference would | |
1790 | * be dropped twice. | |
1791 | * Manfred Spraul <manfred@colorfullife.com> | |
1792 | */ | |
55a101f8 | 1793 | prev_state = prev->state; |
4866cde0 NP |
1794 | finish_arch_switch(prev); |
1795 | finish_lock_switch(rq, prev); | |
1da177e4 LT |
1796 | if (mm) |
1797 | mmdrop(mm); | |
c394cc9f | 1798 | if (unlikely(prev_state == TASK_DEAD)) { |
c6fd91f0 | 1799 | /* |
1800 | * Remove function-return probe instances associated with this | |
1801 | * task and put them back on the free list. | |
1802 | */ | |
1803 | kprobe_flush_task(prev); | |
1da177e4 | 1804 | put_task_struct(prev); |
c6fd91f0 | 1805 | } |
1da177e4 LT |
1806 | } |
1807 | ||
1808 | /** | |
1809 | * schedule_tail - first thing a freshly forked thread must call. | |
1810 | * @prev: the thread we just switched away from. | |
1811 | */ | |
36c8b586 | 1812 | asmlinkage void schedule_tail(struct task_struct *prev) |
1da177e4 LT |
1813 | __releases(rq->lock) |
1814 | { | |
70b97a7f IM |
1815 | struct rq *rq = this_rq(); |
1816 | ||
4866cde0 NP |
1817 | finish_task_switch(rq, prev); |
1818 | #ifdef __ARCH_WANT_UNLOCKED_CTXSW | |
1819 | /* In this case, finish_task_switch does not reenable preemption */ | |
1820 | preempt_enable(); | |
1821 | #endif | |
1da177e4 LT |
1822 | if (current->set_child_tid) |
1823 | put_user(current->pid, current->set_child_tid); | |
1824 | } | |
1825 | ||
1826 | /* | |
1827 | * context_switch - switch to the new MM and the new | |
1828 | * thread's register state. | |
1829 | */ | |
36c8b586 | 1830 | static inline struct task_struct * |
70b97a7f | 1831 | context_switch(struct rq *rq, struct task_struct *prev, |
36c8b586 | 1832 | struct task_struct *next) |
1da177e4 LT |
1833 | { |
1834 | struct mm_struct *mm = next->mm; | |
1835 | struct mm_struct *oldmm = prev->active_mm; | |
1836 | ||
beed33a8 | 1837 | if (!mm) { |
1da177e4 LT |
1838 | next->active_mm = oldmm; |
1839 | atomic_inc(&oldmm->mm_count); | |
1840 | enter_lazy_tlb(oldmm, next); | |
1841 | } else | |
1842 | switch_mm(oldmm, mm, next); | |
1843 | ||
beed33a8 | 1844 | if (!prev->mm) { |
1da177e4 LT |
1845 | prev->active_mm = NULL; |
1846 | WARN_ON(rq->prev_mm); | |
1847 | rq->prev_mm = oldmm; | |
1848 | } | |
3a5f5e48 IM |
1849 | /* |
1850 | * Since the runqueue lock will be released by the next | |
1851 | * task (which is an invalid locking op but in the case | |
1852 | * of the scheduler it's an obvious special-case), so we | |
1853 | * do an early lockdep release here: | |
1854 | */ | |
1855 | #ifndef __ARCH_WANT_UNLOCKED_CTXSW | |
8a25d5de | 1856 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); |
3a5f5e48 | 1857 | #endif |
1da177e4 LT |
1858 | |
1859 | /* Here we just switch the register state and the stack. */ | |
1860 | switch_to(prev, next, prev); | |
1861 | ||
1862 | return prev; | |
1863 | } | |
1864 | ||
1865 | /* | |
1866 | * nr_running, nr_uninterruptible and nr_context_switches: | |
1867 | * | |
1868 | * externally visible scheduler statistics: current number of runnable | |
1869 | * threads, current number of uninterruptible-sleeping threads, total | |
1870 | * number of context switches performed since bootup. | |
1871 | */ | |
1872 | unsigned long nr_running(void) | |
1873 | { | |
1874 | unsigned long i, sum = 0; | |
1875 | ||
1876 | for_each_online_cpu(i) | |
1877 | sum += cpu_rq(i)->nr_running; | |
1878 | ||
1879 | return sum; | |
1880 | } | |
1881 | ||
1882 | unsigned long nr_uninterruptible(void) | |
1883 | { | |
1884 | unsigned long i, sum = 0; | |
1885 | ||
0a945022 | 1886 | for_each_possible_cpu(i) |
1da177e4 LT |
1887 | sum += cpu_rq(i)->nr_uninterruptible; |
1888 | ||
1889 | /* | |
1890 | * Since we read the counters lockless, it might be slightly | |
1891 | * inaccurate. Do not allow it to go below zero though: | |
1892 | */ | |
1893 | if (unlikely((long)sum < 0)) | |
1894 | sum = 0; | |
1895 | ||
1896 | return sum; | |
1897 | } | |
1898 | ||
1899 | unsigned long long nr_context_switches(void) | |
1900 | { | |
cc94abfc SR |
1901 | int i; |
1902 | unsigned long long sum = 0; | |
1da177e4 | 1903 | |
0a945022 | 1904 | for_each_possible_cpu(i) |
1da177e4 LT |
1905 | sum += cpu_rq(i)->nr_switches; |
1906 | ||
1907 | return sum; | |
1908 | } | |
1909 | ||
1910 | unsigned long nr_iowait(void) | |
1911 | { | |
1912 | unsigned long i, sum = 0; | |
1913 | ||
0a945022 | 1914 | for_each_possible_cpu(i) |
1da177e4 LT |
1915 | sum += atomic_read(&cpu_rq(i)->nr_iowait); |
1916 | ||
1917 | return sum; | |
1918 | } | |
1919 | ||
db1b1fef JS |
1920 | unsigned long nr_active(void) |
1921 | { | |
1922 | unsigned long i, running = 0, uninterruptible = 0; | |
1923 | ||
1924 | for_each_online_cpu(i) { | |
1925 | running += cpu_rq(i)->nr_running; | |
1926 | uninterruptible += cpu_rq(i)->nr_uninterruptible; | |
1927 | } | |
1928 | ||
1929 | if (unlikely((long)uninterruptible < 0)) | |
1930 | uninterruptible = 0; | |
1931 | ||
1932 | return running + uninterruptible; | |
1933 | } | |
1934 | ||
1da177e4 LT |
1935 | #ifdef CONFIG_SMP |
1936 | ||
48f24c4d IM |
1937 | /* |
1938 | * Is this task likely cache-hot: | |
1939 | */ | |
1940 | static inline int | |
1941 | task_hot(struct task_struct *p, unsigned long long now, struct sched_domain *sd) | |
1942 | { | |
1943 | return (long long)(now - p->last_ran) < (long long)sd->cache_hot_time; | |
1944 | } | |
1945 | ||
1da177e4 LT |
1946 | /* |
1947 | * double_rq_lock - safely lock two runqueues | |
1948 | * | |
1949 | * Note this does not disable interrupts like task_rq_lock, | |
1950 | * you need to do so manually before calling. | |
1951 | */ | |
70b97a7f | 1952 | static void double_rq_lock(struct rq *rq1, struct rq *rq2) |
1da177e4 LT |
1953 | __acquires(rq1->lock) |
1954 | __acquires(rq2->lock) | |
1955 | { | |
054b9108 | 1956 | BUG_ON(!irqs_disabled()); |
1da177e4 LT |
1957 | if (rq1 == rq2) { |
1958 | spin_lock(&rq1->lock); | |
1959 | __acquire(rq2->lock); /* Fake it out ;) */ | |
1960 | } else { | |
c96d145e | 1961 | if (rq1 < rq2) { |
1da177e4 LT |
1962 | spin_lock(&rq1->lock); |
1963 | spin_lock(&rq2->lock); | |
1964 | } else { | |
1965 | spin_lock(&rq2->lock); | |
1966 | spin_lock(&rq1->lock); | |
1967 | } | |
1968 | } | |
1969 | } | |
1970 | ||
1971 | /* | |
1972 | * double_rq_unlock - safely unlock two runqueues | |
1973 | * | |
1974 | * Note this does not restore interrupts like task_rq_unlock, | |
1975 | * you need to do so manually after calling. | |
1976 | */ | |
70b97a7f | 1977 | static void double_rq_unlock(struct rq *rq1, struct rq *rq2) |
1da177e4 LT |
1978 | __releases(rq1->lock) |
1979 | __releases(rq2->lock) | |
1980 | { | |
1981 | spin_unlock(&rq1->lock); | |
1982 | if (rq1 != rq2) | |
1983 | spin_unlock(&rq2->lock); | |
1984 | else | |
1985 | __release(rq2->lock); | |
1986 | } | |
1987 | ||
1988 | /* | |
1989 | * double_lock_balance - lock the busiest runqueue, this_rq is locked already. | |
1990 | */ | |
70b97a7f | 1991 | static void double_lock_balance(struct rq *this_rq, struct rq *busiest) |
1da177e4 LT |
1992 | __releases(this_rq->lock) |
1993 | __acquires(busiest->lock) | |
1994 | __acquires(this_rq->lock) | |
1995 | { | |
054b9108 KK |
1996 | if (unlikely(!irqs_disabled())) { |
1997 | /* printk() doesn't work good under rq->lock */ | |
1998 | spin_unlock(&this_rq->lock); | |
1999 | BUG_ON(1); | |
2000 | } | |
1da177e4 | 2001 | if (unlikely(!spin_trylock(&busiest->lock))) { |
c96d145e | 2002 | if (busiest < this_rq) { |
1da177e4 LT |
2003 | spin_unlock(&this_rq->lock); |
2004 | spin_lock(&busiest->lock); | |
2005 | spin_lock(&this_rq->lock); | |
2006 | } else | |
2007 | spin_lock(&busiest->lock); | |
2008 | } | |
2009 | } | |
2010 | ||
1da177e4 LT |
2011 | /* |
2012 | * If dest_cpu is allowed for this process, migrate the task to it. | |
2013 | * This is accomplished by forcing the cpu_allowed mask to only | |
2014 | * allow dest_cpu, which will force the cpu onto dest_cpu. Then | |
2015 | * the cpu_allowed mask is restored. | |
2016 | */ | |
36c8b586 | 2017 | static void sched_migrate_task(struct task_struct *p, int dest_cpu) |
1da177e4 | 2018 | { |
70b97a7f | 2019 | struct migration_req req; |
1da177e4 | 2020 | unsigned long flags; |
70b97a7f | 2021 | struct rq *rq; |
1da177e4 LT |
2022 | |
2023 | rq = task_rq_lock(p, &flags); | |
2024 | if (!cpu_isset(dest_cpu, p->cpus_allowed) | |
2025 | || unlikely(cpu_is_offline(dest_cpu))) | |
2026 | goto out; | |
2027 | ||
2028 | /* force the process onto the specified CPU */ | |
2029 | if (migrate_task(p, dest_cpu, &req)) { | |
2030 | /* Need to wait for migration thread (might exit: take ref). */ | |
2031 | struct task_struct *mt = rq->migration_thread; | |
36c8b586 | 2032 | |
1da177e4 LT |
2033 | get_task_struct(mt); |
2034 | task_rq_unlock(rq, &flags); | |
2035 | wake_up_process(mt); | |
2036 | put_task_struct(mt); | |
2037 | wait_for_completion(&req.done); | |
36c8b586 | 2038 | |
1da177e4 LT |
2039 | return; |
2040 | } | |
2041 | out: | |
2042 | task_rq_unlock(rq, &flags); | |
2043 | } | |
2044 | ||
2045 | /* | |
476d139c NP |
2046 | * sched_exec - execve() is a valuable balancing opportunity, because at |
2047 | * this point the task has the smallest effective memory and cache footprint. | |
1da177e4 LT |
2048 | */ |
2049 | void sched_exec(void) | |
2050 | { | |
1da177e4 | 2051 | int new_cpu, this_cpu = get_cpu(); |
476d139c | 2052 | new_cpu = sched_balance_self(this_cpu, SD_BALANCE_EXEC); |
1da177e4 | 2053 | put_cpu(); |
476d139c NP |
2054 | if (new_cpu != this_cpu) |
2055 | sched_migrate_task(current, new_cpu); | |
1da177e4 LT |
2056 | } |
2057 | ||
2058 | /* | |
2059 | * pull_task - move a task from a remote runqueue to the local runqueue. | |
2060 | * Both runqueues must be locked. | |
2061 | */ | |
70b97a7f IM |
2062 | static void pull_task(struct rq *src_rq, struct prio_array *src_array, |
2063 | struct task_struct *p, struct rq *this_rq, | |
2064 | struct prio_array *this_array, int this_cpu) | |
1da177e4 LT |
2065 | { |
2066 | dequeue_task(p, src_array); | |
2dd73a4f | 2067 | dec_nr_running(p, src_rq); |
1da177e4 | 2068 | set_task_cpu(p, this_cpu); |
2dd73a4f | 2069 | inc_nr_running(p, this_rq); |
1da177e4 LT |
2070 | enqueue_task(p, this_array); |
2071 | p->timestamp = (p->timestamp - src_rq->timestamp_last_tick) | |
2072 | + this_rq->timestamp_last_tick; | |
2073 | /* | |
2074 | * Note that idle threads have a prio of MAX_PRIO, for this test | |
2075 | * to be always true for them. | |
2076 | */ | |
2077 | if (TASK_PREEMPTS_CURR(p, this_rq)) | |
2078 | resched_task(this_rq->curr); | |
2079 | } | |
2080 | ||
2081 | /* | |
2082 | * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? | |
2083 | */ | |
858119e1 | 2084 | static |
70b97a7f | 2085 | int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, |
95cdf3b7 IM |
2086 | struct sched_domain *sd, enum idle_type idle, |
2087 | int *all_pinned) | |
1da177e4 LT |
2088 | { |
2089 | /* | |
2090 | * We do not migrate tasks that are: | |
2091 | * 1) running (obviously), or | |
2092 | * 2) cannot be migrated to this CPU due to cpus_allowed, or | |
2093 | * 3) are cache-hot on their current CPU. | |
2094 | */ | |
1da177e4 LT |
2095 | if (!cpu_isset(this_cpu, p->cpus_allowed)) |
2096 | return 0; | |
81026794 NP |
2097 | *all_pinned = 0; |
2098 | ||
2099 | if (task_running(rq, p)) | |
2100 | return 0; | |
1da177e4 LT |
2101 | |
2102 | /* | |
2103 | * Aggressive migration if: | |
cafb20c1 | 2104 | * 1) task is cache cold, or |
1da177e4 LT |
2105 | * 2) too many balance attempts have failed. |
2106 | */ | |
2107 | ||
cafb20c1 | 2108 | if (sd->nr_balance_failed > sd->cache_nice_tries) |
1da177e4 LT |
2109 | return 1; |
2110 | ||
2111 | if (task_hot(p, rq->timestamp_last_tick, sd)) | |
81026794 | 2112 | return 0; |
1da177e4 LT |
2113 | return 1; |
2114 | } | |
2115 | ||
615052dc | 2116 | #define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio) |
48f24c4d | 2117 | |
1da177e4 | 2118 | /* |
2dd73a4f PW |
2119 | * move_tasks tries to move up to max_nr_move tasks and max_load_move weighted |
2120 | * load from busiest to this_rq, as part of a balancing operation within | |
2121 | * "domain". Returns the number of tasks moved. | |
1da177e4 LT |
2122 | * |
2123 | * Called with both runqueues locked. | |
2124 | */ | |
70b97a7f | 2125 | static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, |
2dd73a4f PW |
2126 | unsigned long max_nr_move, unsigned long max_load_move, |
2127 | struct sched_domain *sd, enum idle_type idle, | |
2128 | int *all_pinned) | |
1da177e4 | 2129 | { |
48f24c4d IM |
2130 | int idx, pulled = 0, pinned = 0, this_best_prio, best_prio, |
2131 | best_prio_seen, skip_for_load; | |
70b97a7f | 2132 | struct prio_array *array, *dst_array; |
1da177e4 | 2133 | struct list_head *head, *curr; |
36c8b586 | 2134 | struct task_struct *tmp; |
2dd73a4f | 2135 | long rem_load_move; |
1da177e4 | 2136 | |
2dd73a4f | 2137 | if (max_nr_move == 0 || max_load_move == 0) |
1da177e4 LT |
2138 | goto out; |
2139 | ||
2dd73a4f | 2140 | rem_load_move = max_load_move; |
81026794 | 2141 | pinned = 1; |
615052dc | 2142 | this_best_prio = rq_best_prio(this_rq); |
48f24c4d | 2143 | best_prio = rq_best_prio(busiest); |
615052dc PW |
2144 | /* |
2145 | * Enable handling of the case where there is more than one task | |
2146 | * with the best priority. If the current running task is one | |
48f24c4d | 2147 | * of those with prio==best_prio we know it won't be moved |
615052dc PW |
2148 | * and therefore it's safe to override the skip (based on load) of |
2149 | * any task we find with that prio. | |
2150 | */ | |
48f24c4d | 2151 | best_prio_seen = best_prio == busiest->curr->prio; |
81026794 | 2152 | |
1da177e4 LT |
2153 | /* |
2154 | * We first consider expired tasks. Those will likely not be | |
2155 | * executed in the near future, and they are most likely to | |
2156 | * be cache-cold, thus switching CPUs has the least effect | |
2157 | * on them. | |
2158 | */ | |
2159 | if (busiest->expired->nr_active) { | |
2160 | array = busiest->expired; | |
2161 | dst_array = this_rq->expired; | |
2162 | } else { | |
2163 | array = busiest->active; | |
2164 | dst_array = this_rq->active; | |
2165 | } | |
2166 | ||
2167 | new_array: | |
2168 | /* Start searching at priority 0: */ | |
2169 | idx = 0; | |
2170 | skip_bitmap: | |
2171 | if (!idx) | |
2172 | idx = sched_find_first_bit(array->bitmap); | |
2173 | else | |
2174 | idx = find_next_bit(array->bitmap, MAX_PRIO, idx); | |
2175 | if (idx >= MAX_PRIO) { | |
2176 | if (array == busiest->expired && busiest->active->nr_active) { | |
2177 | array = busiest->active; | |
2178 | dst_array = this_rq->active; | |
2179 | goto new_array; | |
2180 | } | |
2181 | goto out; | |
2182 | } | |
2183 | ||
2184 | head = array->queue + idx; | |
2185 | curr = head->prev; | |
2186 | skip_queue: | |
36c8b586 | 2187 | tmp = list_entry(curr, struct task_struct, run_list); |
1da177e4 LT |
2188 | |
2189 | curr = curr->prev; | |
2190 | ||
50ddd969 PW |
2191 | /* |
2192 | * To help distribute high priority tasks accross CPUs we don't | |
2193 | * skip a task if it will be the highest priority task (i.e. smallest | |
2194 | * prio value) on its new queue regardless of its load weight | |
2195 | */ | |
615052dc PW |
2196 | skip_for_load = tmp->load_weight > rem_load_move; |
2197 | if (skip_for_load && idx < this_best_prio) | |
48f24c4d | 2198 | skip_for_load = !best_prio_seen && idx == best_prio; |
615052dc | 2199 | if (skip_for_load || |
2dd73a4f | 2200 | !can_migrate_task(tmp, busiest, this_cpu, sd, idle, &pinned)) { |
48f24c4d IM |
2201 | |
2202 | best_prio_seen |= idx == best_prio; | |
1da177e4 LT |
2203 | if (curr != head) |
2204 | goto skip_queue; | |
2205 | idx++; | |
2206 | goto skip_bitmap; | |
2207 | } | |
2208 | ||
2209 | #ifdef CONFIG_SCHEDSTATS | |
2210 | if (task_hot(tmp, busiest->timestamp_last_tick, sd)) | |
2211 | schedstat_inc(sd, lb_hot_gained[idle]); | |
2212 | #endif | |
2213 | ||
2214 | pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu); | |
2215 | pulled++; | |
2dd73a4f | 2216 | rem_load_move -= tmp->load_weight; |
1da177e4 | 2217 | |
2dd73a4f PW |
2218 | /* |
2219 | * We only want to steal up to the prescribed number of tasks | |
2220 | * and the prescribed amount of weighted load. | |
2221 | */ | |
2222 | if (pulled < max_nr_move && rem_load_move > 0) { | |
615052dc PW |
2223 | if (idx < this_best_prio) |
2224 | this_best_prio = idx; | |
1da177e4 LT |
2225 | if (curr != head) |
2226 | goto skip_queue; | |
2227 | idx++; | |
2228 | goto skip_bitmap; | |
2229 | } | |
2230 | out: | |
2231 | /* | |
2232 | * Right now, this is the only place pull_task() is called, | |
2233 | * so we can safely collect pull_task() stats here rather than | |
2234 | * inside pull_task(). | |
2235 | */ | |
2236 | schedstat_add(sd, lb_gained[idle], pulled); | |
81026794 NP |
2237 | |
2238 | if (all_pinned) | |
2239 | *all_pinned = pinned; | |
1da177e4 LT |
2240 | return pulled; |
2241 | } | |
2242 | ||
2243 | /* | |
2244 | * find_busiest_group finds and returns the busiest CPU group within the | |
48f24c4d IM |
2245 | * domain. It calculates and returns the amount of weighted load which |
2246 | * should be moved to restore balance via the imbalance parameter. | |
1da177e4 LT |
2247 | */ |
2248 | static struct sched_group * | |
2249 | find_busiest_group(struct sched_domain *sd, int this_cpu, | |
0a2966b4 CL |
2250 | unsigned long *imbalance, enum idle_type idle, int *sd_idle, |
2251 | cpumask_t *cpus) | |
1da177e4 LT |
2252 | { |
2253 | struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups; | |
2254 | unsigned long max_load, avg_load, total_load, this_load, total_pwr; | |
0c117f1b | 2255 | unsigned long max_pull; |
2dd73a4f PW |
2256 | unsigned long busiest_load_per_task, busiest_nr_running; |
2257 | unsigned long this_load_per_task, this_nr_running; | |
7897986b | 2258 | int load_idx; |
5c45bf27 SS |
2259 | #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) |
2260 | int power_savings_balance = 1; | |
2261 | unsigned long leader_nr_running = 0, min_load_per_task = 0; | |
2262 | unsigned long min_nr_running = ULONG_MAX; | |
2263 | struct sched_group *group_min = NULL, *group_leader = NULL; | |
2264 | #endif | |
1da177e4 LT |
2265 | |
2266 | max_load = this_load = total_load = total_pwr = 0; | |
2dd73a4f PW |
2267 | busiest_load_per_task = busiest_nr_running = 0; |
2268 | this_load_per_task = this_nr_running = 0; | |
7897986b NP |
2269 | if (idle == NOT_IDLE) |
2270 | load_idx = sd->busy_idx; | |
2271 | else if (idle == NEWLY_IDLE) | |
2272 | load_idx = sd->newidle_idx; | |
2273 | else | |
2274 | load_idx = sd->idle_idx; | |
1da177e4 LT |
2275 | |
2276 | do { | |
5c45bf27 | 2277 | unsigned long load, group_capacity; |
1da177e4 LT |
2278 | int local_group; |
2279 | int i; | |
2dd73a4f | 2280 | unsigned long sum_nr_running, sum_weighted_load; |
1da177e4 LT |
2281 | |
2282 | local_group = cpu_isset(this_cpu, group->cpumask); | |
2283 | ||
2284 | /* Tally up the load of all CPUs in the group */ | |
2dd73a4f | 2285 | sum_weighted_load = sum_nr_running = avg_load = 0; |
1da177e4 LT |
2286 | |
2287 | for_each_cpu_mask(i, group->cpumask) { | |
0a2966b4 CL |
2288 | struct rq *rq; |
2289 | ||
2290 | if (!cpu_isset(i, *cpus)) | |
2291 | continue; | |
2292 | ||
2293 | rq = cpu_rq(i); | |
2dd73a4f | 2294 | |
5969fe06 NP |
2295 | if (*sd_idle && !idle_cpu(i)) |
2296 | *sd_idle = 0; | |
2297 | ||
1da177e4 LT |
2298 | /* Bias balancing toward cpus of our domain */ |
2299 | if (local_group) | |
a2000572 | 2300 | load = target_load(i, load_idx); |
1da177e4 | 2301 | else |
a2000572 | 2302 | load = source_load(i, load_idx); |
1da177e4 LT |
2303 | |
2304 | avg_load += load; | |
2dd73a4f PW |
2305 | sum_nr_running += rq->nr_running; |
2306 | sum_weighted_load += rq->raw_weighted_load; | |
1da177e4 LT |
2307 | } |
2308 | ||
2309 | total_load += avg_load; | |
2310 | total_pwr += group->cpu_power; | |
2311 | ||
2312 | /* Adjust by relative CPU power of the group */ | |
2313 | avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power; | |
2314 | ||
5c45bf27 SS |
2315 | group_capacity = group->cpu_power / SCHED_LOAD_SCALE; |
2316 | ||
1da177e4 LT |
2317 | if (local_group) { |
2318 | this_load = avg_load; | |
2319 | this = group; | |
2dd73a4f PW |
2320 | this_nr_running = sum_nr_running; |
2321 | this_load_per_task = sum_weighted_load; | |
2322 | } else if (avg_load > max_load && | |
5c45bf27 | 2323 | sum_nr_running > group_capacity) { |
1da177e4 LT |
2324 | max_load = avg_load; |
2325 | busiest = group; | |
2dd73a4f PW |
2326 | busiest_nr_running = sum_nr_running; |
2327 | busiest_load_per_task = sum_weighted_load; | |
1da177e4 | 2328 | } |
5c45bf27 SS |
2329 | |
2330 | #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) | |
2331 | /* | |
2332 | * Busy processors will not participate in power savings | |
2333 | * balance. | |
2334 | */ | |
2335 | if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) | |
2336 | goto group_next; | |
2337 | ||
2338 | /* | |
2339 | * If the local group is idle or completely loaded | |
2340 | * no need to do power savings balance at this domain | |
2341 | */ | |
2342 | if (local_group && (this_nr_running >= group_capacity || | |
2343 | !this_nr_running)) | |
2344 | power_savings_balance = 0; | |
2345 | ||
2346 | /* | |
2347 | * If a group is already running at full capacity or idle, | |
2348 | * don't include that group in power savings calculations | |
2349 | */ | |
2350 | if (!power_savings_balance || sum_nr_running >= group_capacity | |
2351 | || !sum_nr_running) | |
2352 | goto group_next; | |
2353 | ||
2354 | /* | |
2355 | * Calculate the group which has the least non-idle load. | |
2356 | * This is the group from where we need to pick up the load | |
2357 | * for saving power | |
2358 | */ | |
2359 | if ((sum_nr_running < min_nr_running) || | |
2360 | (sum_nr_running == min_nr_running && | |
2361 | first_cpu(group->cpumask) < | |
2362 | first_cpu(group_min->cpumask))) { | |
2363 | group_min = group; | |
2364 | min_nr_running = sum_nr_running; | |
2365 | min_load_per_task = sum_weighted_load / | |
2366 | sum_nr_running; | |
2367 | } | |
2368 | ||
2369 | /* | |
2370 | * Calculate the group which is almost near its | |
2371 | * capacity but still has some space to pick up some load | |
2372 | * from other group and save more power | |
2373 | */ | |
48f24c4d | 2374 | if (sum_nr_running <= group_capacity - 1) { |
5c45bf27 SS |
2375 | if (sum_nr_running > leader_nr_running || |
2376 | (sum_nr_running == leader_nr_running && | |
2377 | first_cpu(group->cpumask) > | |
2378 | first_cpu(group_leader->cpumask))) { | |
2379 | group_leader = group; | |
2380 | leader_nr_running = sum_nr_running; | |
2381 | } | |
48f24c4d | 2382 | } |
5c45bf27 SS |
2383 | group_next: |
2384 | #endif | |
1da177e4 LT |
2385 | group = group->next; |
2386 | } while (group != sd->groups); | |
2387 | ||
2dd73a4f | 2388 | if (!busiest || this_load >= max_load || busiest_nr_running == 0) |
1da177e4 LT |
2389 | goto out_balanced; |
2390 | ||
2391 | avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr; | |
2392 | ||
2393 | if (this_load >= avg_load || | |
2394 | 100*max_load <= sd->imbalance_pct*this_load) | |
2395 | goto out_balanced; | |
2396 | ||
2dd73a4f | 2397 | busiest_load_per_task /= busiest_nr_running; |
1da177e4 LT |
2398 | /* |
2399 | * We're trying to get all the cpus to the average_load, so we don't | |
2400 | * want to push ourselves above the average load, nor do we wish to | |
2401 | * reduce the max loaded cpu below the average load, as either of these | |
2402 | * actions would just result in more rebalancing later, and ping-pong | |
2403 | * tasks around. Thus we look for the minimum possible imbalance. | |
2404 | * Negative imbalances (*we* are more loaded than anyone else) will | |
2405 | * be counted as no imbalance for these purposes -- we can't fix that | |
2406 | * by pulling tasks to us. Be careful of negative numbers as they'll | |
2407 | * appear as very large values with unsigned longs. | |
2408 | */ | |
2dd73a4f PW |
2409 | if (max_load <= busiest_load_per_task) |
2410 | goto out_balanced; | |
2411 | ||
2412 | /* | |
2413 | * In the presence of smp nice balancing, certain scenarios can have | |
2414 | * max load less than avg load(as we skip the groups at or below | |
2415 | * its cpu_power, while calculating max_load..) | |
2416 | */ | |
2417 | if (max_load < avg_load) { | |
2418 | *imbalance = 0; | |
2419 | goto small_imbalance; | |
2420 | } | |
0c117f1b SS |
2421 | |
2422 | /* Don't want to pull so many tasks that a group would go idle */ | |
2dd73a4f | 2423 | max_pull = min(max_load - avg_load, max_load - busiest_load_per_task); |
0c117f1b | 2424 | |
1da177e4 | 2425 | /* How much load to actually move to equalise the imbalance */ |
0c117f1b | 2426 | *imbalance = min(max_pull * busiest->cpu_power, |
1da177e4 LT |
2427 | (avg_load - this_load) * this->cpu_power) |
2428 | / SCHED_LOAD_SCALE; | |
2429 | ||
2dd73a4f PW |
2430 | /* |
2431 | * if *imbalance is less than the average load per runnable task | |
2432 | * there is no gaurantee that any tasks will be moved so we'll have | |
2433 | * a think about bumping its value to force at least one task to be | |
2434 | * moved | |
2435 | */ | |
2436 | if (*imbalance < busiest_load_per_task) { | |
48f24c4d | 2437 | unsigned long tmp, pwr_now, pwr_move; |
2dd73a4f PW |
2438 | unsigned int imbn; |
2439 | ||
2440 | small_imbalance: | |
2441 | pwr_move = pwr_now = 0; | |
2442 | imbn = 2; | |
2443 | if (this_nr_running) { | |
2444 | this_load_per_task /= this_nr_running; | |
2445 | if (busiest_load_per_task > this_load_per_task) | |
2446 | imbn = 1; | |
2447 | } else | |
2448 | this_load_per_task = SCHED_LOAD_SCALE; | |
1da177e4 | 2449 | |
2dd73a4f PW |
2450 | if (max_load - this_load >= busiest_load_per_task * imbn) { |
2451 | *imbalance = busiest_load_per_task; | |
1da177e4 LT |
2452 | return busiest; |
2453 | } | |
2454 | ||
2455 | /* | |
2456 | * OK, we don't have enough imbalance to justify moving tasks, | |
2457 | * however we may be able to increase total CPU power used by | |
2458 | * moving them. | |
2459 | */ | |
2460 | ||
2dd73a4f PW |
2461 | pwr_now += busiest->cpu_power * |
2462 | min(busiest_load_per_task, max_load); | |
2463 | pwr_now += this->cpu_power * | |
2464 | min(this_load_per_task, this_load); | |
1da177e4 LT |
2465 | pwr_now /= SCHED_LOAD_SCALE; |
2466 | ||
2467 | /* Amount of load we'd subtract */ | |
2dd73a4f | 2468 | tmp = busiest_load_per_task*SCHED_LOAD_SCALE/busiest->cpu_power; |
1da177e4 | 2469 | if (max_load > tmp) |
2dd73a4f PW |
2470 | pwr_move += busiest->cpu_power * |
2471 | min(busiest_load_per_task, max_load - tmp); | |
1da177e4 LT |
2472 | |
2473 | /* Amount of load we'd add */ | |
2474 | if (max_load*busiest->cpu_power < | |
2dd73a4f | 2475 | busiest_load_per_task*SCHED_LOAD_SCALE) |
1da177e4 LT |
2476 | tmp = max_load*busiest->cpu_power/this->cpu_power; |
2477 | else | |
2dd73a4f PW |
2478 | tmp = busiest_load_per_task*SCHED_LOAD_SCALE/this->cpu_power; |
2479 | pwr_move += this->cpu_power*min(this_load_per_task, this_load + tmp); | |
1da177e4 LT |
2480 | pwr_move /= SCHED_LOAD_SCALE; |
2481 | ||
2482 | /* Move if we gain throughput */ | |
2483 | if (pwr_move <= pwr_now) | |
2484 | goto out_balanced; | |
2485 | ||
2dd73a4f | 2486 | *imbalance = busiest_load_per_task; |
1da177e4 LT |
2487 | } |
2488 | ||
1da177e4 LT |
2489 | return busiest; |
2490 | ||
2491 | out_balanced: | |
5c45bf27 SS |
2492 | #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) |
2493 | if (idle == NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) | |
2494 | goto ret; | |
1da177e4 | 2495 | |
5c45bf27 SS |
2496 | if (this == group_leader && group_leader != group_min) { |
2497 | *imbalance = min_load_per_task; | |
2498 | return group_min; | |
2499 | } | |
2500 | ret: | |
2501 | #endif | |
1da177e4 LT |
2502 | *imbalance = 0; |
2503 | return NULL; | |
2504 | } | |
2505 | ||
2506 | /* | |
2507 | * find_busiest_queue - find the busiest runqueue among the cpus in group. | |
2508 | */ | |
70b97a7f | 2509 | static struct rq * |
48f24c4d | 2510 | find_busiest_queue(struct sched_group *group, enum idle_type idle, |
0a2966b4 | 2511 | unsigned long imbalance, cpumask_t *cpus) |
1da177e4 | 2512 | { |
70b97a7f | 2513 | struct rq *busiest = NULL, *rq; |
2dd73a4f | 2514 | unsigned long max_load = 0; |
1da177e4 LT |
2515 | int i; |
2516 | ||
2517 | for_each_cpu_mask(i, group->cpumask) { | |
0a2966b4 CL |
2518 | |
2519 | if (!cpu_isset(i, *cpus)) | |
2520 | continue; | |
2521 | ||
48f24c4d | 2522 | rq = cpu_rq(i); |
2dd73a4f | 2523 | |
48f24c4d | 2524 | if (rq->nr_running == 1 && rq->raw_weighted_load > imbalance) |
2dd73a4f | 2525 | continue; |
1da177e4 | 2526 | |
48f24c4d IM |
2527 | if (rq->raw_weighted_load > max_load) { |
2528 | max_load = rq->raw_weighted_load; | |
2529 | busiest = rq; | |
1da177e4 LT |
2530 | } |
2531 | } | |
2532 | ||
2533 | return busiest; | |
2534 | } | |
2535 | ||
77391d71 NP |
2536 | /* |
2537 | * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but | |
2538 | * so long as it is large enough. | |
2539 | */ | |
2540 | #define MAX_PINNED_INTERVAL 512 | |
2541 | ||
48f24c4d IM |
2542 | static inline unsigned long minus_1_or_zero(unsigned long n) |
2543 | { | |
2544 | return n > 0 ? n - 1 : 0; | |
2545 | } | |
2546 | ||
1da177e4 LT |
2547 | /* |
2548 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
2549 | * tasks if there is an imbalance. | |
1da177e4 | 2550 | */ |
70b97a7f | 2551 | static int load_balance(int this_cpu, struct rq *this_rq, |
1da177e4 LT |
2552 | struct sched_domain *sd, enum idle_type idle) |
2553 | { | |
48f24c4d | 2554 | int nr_moved, all_pinned = 0, active_balance = 0, sd_idle = 0; |
1da177e4 | 2555 | struct sched_group *group; |
1da177e4 | 2556 | unsigned long imbalance; |
70b97a7f | 2557 | struct rq *busiest; |
0a2966b4 | 2558 | cpumask_t cpus = CPU_MASK_ALL; |
fe2eea3f | 2559 | unsigned long flags; |
5969fe06 | 2560 | |
89c4710e SS |
2561 | /* |
2562 | * When power savings policy is enabled for the parent domain, idle | |
2563 | * sibling can pick up load irrespective of busy siblings. In this case, | |
2564 | * let the state of idle sibling percolate up as IDLE, instead of | |
2565 | * portraying it as NOT_IDLE. | |
2566 | */ | |
5c45bf27 | 2567 | if (idle != NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER && |
89c4710e | 2568 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) |
5969fe06 | 2569 | sd_idle = 1; |
1da177e4 | 2570 | |
1da177e4 LT |
2571 | schedstat_inc(sd, lb_cnt[idle]); |
2572 | ||
0a2966b4 CL |
2573 | redo: |
2574 | group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle, | |
2575 | &cpus); | |
1da177e4 LT |
2576 | if (!group) { |
2577 | schedstat_inc(sd, lb_nobusyg[idle]); | |
2578 | goto out_balanced; | |
2579 | } | |
2580 | ||
0a2966b4 | 2581 | busiest = find_busiest_queue(group, idle, imbalance, &cpus); |
1da177e4 LT |
2582 | if (!busiest) { |
2583 | schedstat_inc(sd, lb_nobusyq[idle]); | |
2584 | goto out_balanced; | |
2585 | } | |
2586 | ||
db935dbd | 2587 | BUG_ON(busiest == this_rq); |
1da177e4 LT |
2588 | |
2589 | schedstat_add(sd, lb_imbalance[idle], imbalance); | |
2590 | ||
2591 | nr_moved = 0; | |
2592 | if (busiest->nr_running > 1) { | |
2593 | /* | |
2594 | * Attempt to move tasks. If find_busiest_group has found | |
2595 | * an imbalance but busiest->nr_running <= 1, the group is | |
2596 | * still unbalanced. nr_moved simply stays zero, so it is | |
2597 | * correctly treated as an imbalance. | |
2598 | */ | |
fe2eea3f | 2599 | local_irq_save(flags); |
e17224bf | 2600 | double_rq_lock(this_rq, busiest); |
1da177e4 | 2601 | nr_moved = move_tasks(this_rq, this_cpu, busiest, |
48f24c4d IM |
2602 | minus_1_or_zero(busiest->nr_running), |
2603 | imbalance, sd, idle, &all_pinned); | |
e17224bf | 2604 | double_rq_unlock(this_rq, busiest); |
fe2eea3f | 2605 | local_irq_restore(flags); |
81026794 NP |
2606 | |
2607 | /* All tasks on this runqueue were pinned by CPU affinity */ | |
0a2966b4 CL |
2608 | if (unlikely(all_pinned)) { |
2609 | cpu_clear(cpu_of(busiest), cpus); | |
2610 | if (!cpus_empty(cpus)) | |
2611 | goto redo; | |
81026794 | 2612 | goto out_balanced; |
0a2966b4 | 2613 | } |
1da177e4 | 2614 | } |
81026794 | 2615 | |
1da177e4 LT |
2616 | if (!nr_moved) { |
2617 | schedstat_inc(sd, lb_failed[idle]); | |
2618 | sd->nr_balance_failed++; | |
2619 | ||
2620 | if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { | |
1da177e4 | 2621 | |
fe2eea3f | 2622 | spin_lock_irqsave(&busiest->lock, flags); |
fa3b6ddc SS |
2623 | |
2624 | /* don't kick the migration_thread, if the curr | |
2625 | * task on busiest cpu can't be moved to this_cpu | |
2626 | */ | |
2627 | if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) { | |
fe2eea3f | 2628 | spin_unlock_irqrestore(&busiest->lock, flags); |
fa3b6ddc SS |
2629 | all_pinned = 1; |
2630 | goto out_one_pinned; | |
2631 | } | |
2632 | ||
1da177e4 LT |
2633 | if (!busiest->active_balance) { |
2634 | busiest->active_balance = 1; | |
2635 | busiest->push_cpu = this_cpu; | |
81026794 | 2636 | active_balance = 1; |
1da177e4 | 2637 | } |
fe2eea3f | 2638 | spin_unlock_irqrestore(&busiest->lock, flags); |
81026794 | 2639 | if (active_balance) |
1da177e4 LT |
2640 | wake_up_process(busiest->migration_thread); |
2641 | ||
2642 | /* | |
2643 | * We've kicked active balancing, reset the failure | |
2644 | * counter. | |
2645 | */ | |
39507451 | 2646 | sd->nr_balance_failed = sd->cache_nice_tries+1; |
1da177e4 | 2647 | } |
81026794 | 2648 | } else |
1da177e4 LT |
2649 | sd->nr_balance_failed = 0; |
2650 | ||
81026794 | 2651 | if (likely(!active_balance)) { |
1da177e4 LT |
2652 | /* We were unbalanced, so reset the balancing interval */ |
2653 | sd->balance_interval = sd->min_interval; | |
81026794 NP |
2654 | } else { |
2655 | /* | |
2656 | * If we've begun active balancing, start to back off. This | |
2657 | * case may not be covered by the all_pinned logic if there | |
2658 | * is only 1 task on the busy runqueue (because we don't call | |
2659 | * move_tasks). | |
2660 | */ | |
2661 | if (sd->balance_interval < sd->max_interval) | |
2662 | sd->balance_interval *= 2; | |
1da177e4 LT |
2663 | } |
2664 | ||
5c45bf27 | 2665 | if (!nr_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER && |
89c4710e | 2666 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) |
5969fe06 | 2667 | return -1; |
1da177e4 LT |
2668 | return nr_moved; |
2669 | ||
2670 | out_balanced: | |
1da177e4 LT |
2671 | schedstat_inc(sd, lb_balanced[idle]); |
2672 | ||
16cfb1c0 | 2673 | sd->nr_balance_failed = 0; |
fa3b6ddc SS |
2674 | |
2675 | out_one_pinned: | |
1da177e4 | 2676 | /* tune up the balancing interval */ |
77391d71 NP |
2677 | if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) || |
2678 | (sd->balance_interval < sd->max_interval)) | |
1da177e4 LT |
2679 | sd->balance_interval *= 2; |
2680 | ||
48f24c4d | 2681 | if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && |
89c4710e | 2682 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) |
5969fe06 | 2683 | return -1; |
1da177e4 LT |
2684 | return 0; |
2685 | } | |
2686 | ||
2687 | /* | |
2688 | * Check this_cpu to ensure it is balanced within domain. Attempt to move | |
2689 | * tasks if there is an imbalance. | |
2690 | * | |
2691 | * Called from schedule when this_rq is about to become idle (NEWLY_IDLE). | |
2692 | * this_rq is locked. | |
2693 | */ | |
48f24c4d | 2694 | static int |
70b97a7f | 2695 | load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd) |
1da177e4 LT |
2696 | { |
2697 | struct sched_group *group; | |
70b97a7f | 2698 | struct rq *busiest = NULL; |
1da177e4 LT |
2699 | unsigned long imbalance; |
2700 | int nr_moved = 0; | |
5969fe06 | 2701 | int sd_idle = 0; |
0a2966b4 | 2702 | cpumask_t cpus = CPU_MASK_ALL; |
5969fe06 | 2703 | |
89c4710e SS |
2704 | /* |
2705 | * When power savings policy is enabled for the parent domain, idle | |
2706 | * sibling can pick up load irrespective of busy siblings. In this case, | |
2707 | * let the state of idle sibling percolate up as IDLE, instead of | |
2708 | * portraying it as NOT_IDLE. | |
2709 | */ | |
2710 | if (sd->flags & SD_SHARE_CPUPOWER && | |
2711 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) | |
5969fe06 | 2712 | sd_idle = 1; |
1da177e4 LT |
2713 | |
2714 | schedstat_inc(sd, lb_cnt[NEWLY_IDLE]); | |
0a2966b4 CL |
2715 | redo: |
2716 | group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE, | |
2717 | &sd_idle, &cpus); | |
1da177e4 | 2718 | if (!group) { |
1da177e4 | 2719 | schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]); |
16cfb1c0 | 2720 | goto out_balanced; |
1da177e4 LT |
2721 | } |
2722 | ||
0a2966b4 CL |
2723 | busiest = find_busiest_queue(group, NEWLY_IDLE, imbalance, |
2724 | &cpus); | |
db935dbd | 2725 | if (!busiest) { |
1da177e4 | 2726 | schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]); |
16cfb1c0 | 2727 | goto out_balanced; |
1da177e4 LT |
2728 | } |
2729 | ||
db935dbd NP |
2730 | BUG_ON(busiest == this_rq); |
2731 | ||
1da177e4 | 2732 | schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance); |
d6d5cfaf NP |
2733 | |
2734 | nr_moved = 0; | |
2735 | if (busiest->nr_running > 1) { | |
2736 | /* Attempt to move tasks */ | |
2737 | double_lock_balance(this_rq, busiest); | |
2738 | nr_moved = move_tasks(this_rq, this_cpu, busiest, | |
2dd73a4f | 2739 | minus_1_or_zero(busiest->nr_running), |
81026794 | 2740 | imbalance, sd, NEWLY_IDLE, NULL); |
d6d5cfaf | 2741 | spin_unlock(&busiest->lock); |
0a2966b4 CL |
2742 | |
2743 | if (!nr_moved) { | |
2744 | cpu_clear(cpu_of(busiest), cpus); | |
2745 | if (!cpus_empty(cpus)) | |
2746 | goto redo; | |
2747 | } | |
d6d5cfaf NP |
2748 | } |
2749 | ||
5969fe06 | 2750 | if (!nr_moved) { |
1da177e4 | 2751 | schedstat_inc(sd, lb_failed[NEWLY_IDLE]); |
89c4710e SS |
2752 | if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && |
2753 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) | |
5969fe06 NP |
2754 | return -1; |
2755 | } else | |
16cfb1c0 | 2756 | sd->nr_balance_failed = 0; |
1da177e4 | 2757 | |
1da177e4 | 2758 | return nr_moved; |
16cfb1c0 NP |
2759 | |
2760 | out_balanced: | |
2761 | schedstat_inc(sd, lb_balanced[NEWLY_IDLE]); | |
48f24c4d | 2762 | if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER && |
89c4710e | 2763 | !test_sd_parent(sd, SD_POWERSAVINGS_BALANCE)) |
5969fe06 | 2764 | return -1; |
16cfb1c0 | 2765 | sd->nr_balance_failed = 0; |
48f24c4d | 2766 | |
16cfb1c0 | 2767 | return 0; |
1da177e4 LT |
2768 | } |
2769 | ||
2770 | /* | |
2771 | * idle_balance is called by schedule() if this_cpu is about to become | |
2772 | * idle. Attempts to pull tasks from other CPUs. | |
2773 | */ | |
70b97a7f | 2774 | static void idle_balance(int this_cpu, struct rq *this_rq) |
1da177e4 LT |
2775 | { |
2776 | struct sched_domain *sd; | |
1bd77f2d CL |
2777 | int pulled_task = 0; |
2778 | unsigned long next_balance = jiffies + 60 * HZ; | |
1da177e4 LT |
2779 | |
2780 | for_each_domain(this_cpu, sd) { | |
2781 | if (sd->flags & SD_BALANCE_NEWIDLE) { | |
48f24c4d | 2782 | /* If we've pulled tasks over stop searching: */ |
1bd77f2d CL |
2783 | pulled_task = load_balance_newidle(this_cpu, |
2784 | this_rq, sd); | |
2785 | if (time_after(next_balance, | |
2786 | sd->last_balance + sd->balance_interval)) | |
2787 | next_balance = sd->last_balance | |
2788 | + sd->balance_interval; | |
2789 | if (pulled_task) | |
1da177e4 | 2790 | break; |
1da177e4 LT |
2791 | } |
2792 | } | |
1bd77f2d CL |
2793 | if (!pulled_task) |
2794 | /* | |
2795 | * We are going idle. next_balance may be set based on | |
2796 | * a busy processor. So reset next_balance. | |
2797 | */ | |
2798 | this_rq->next_balance = next_balance; | |
1da177e4 LT |
2799 | } |
2800 | ||
2801 | /* | |
2802 | * active_load_balance is run by migration threads. It pushes running tasks | |
2803 | * off the busiest CPU onto idle CPUs. It requires at least 1 task to be | |
2804 | * running on each physical CPU where possible, and avoids physical / | |
2805 | * logical imbalances. | |
2806 | * | |
2807 | * Called with busiest_rq locked. | |
2808 | */ | |
70b97a7f | 2809 | static void active_load_balance(struct rq *busiest_rq, int busiest_cpu) |
1da177e4 | 2810 | { |
39507451 | 2811 | int target_cpu = busiest_rq->push_cpu; |
70b97a7f IM |
2812 | struct sched_domain *sd; |
2813 | struct rq *target_rq; | |
39507451 | 2814 | |
48f24c4d | 2815 | /* Is there any task to move? */ |
39507451 | 2816 | if (busiest_rq->nr_running <= 1) |
39507451 NP |
2817 | return; |
2818 | ||
2819 | target_rq = cpu_rq(target_cpu); | |
1da177e4 LT |
2820 | |
2821 | /* | |
39507451 NP |
2822 | * This condition is "impossible", if it occurs |
2823 | * we need to fix it. Originally reported by | |
2824 | * Bjorn Helgaas on a 128-cpu setup. | |
1da177e4 | 2825 | */ |
39507451 | 2826 | BUG_ON(busiest_rq == target_rq); |
1da177e4 | 2827 | |
39507451 NP |
2828 | /* move a task from busiest_rq to target_rq */ |
2829 | double_lock_balance(busiest_rq, target_rq); | |
2830 | ||
2831 | /* Search for an sd spanning us and the target CPU. */ | |
c96d145e | 2832 | for_each_domain(target_cpu, sd) { |
39507451 | 2833 | if ((sd->flags & SD_LOAD_BALANCE) && |
48f24c4d | 2834 | cpu_isset(busiest_cpu, sd->span)) |
39507451 | 2835 | break; |
c96d145e | 2836 | } |
39507451 | 2837 | |
48f24c4d IM |
2838 | if (likely(sd)) { |
2839 | schedstat_inc(sd, alb_cnt); | |
39507451 | 2840 | |
48f24c4d IM |
2841 | if (move_tasks(target_rq, target_cpu, busiest_rq, 1, |
2842 | RTPRIO_TO_LOAD_WEIGHT(100), sd, SCHED_IDLE, | |
2843 | NULL)) | |
2844 | schedstat_inc(sd, alb_pushed); | |
2845 | else | |
2846 | schedstat_inc(sd, alb_failed); | |
2847 | } | |
39507451 | 2848 | spin_unlock(&target_rq->lock); |
1da177e4 LT |
2849 | } |
2850 | ||
7835b98b | 2851 | static void update_load(struct rq *this_rq) |
1da177e4 | 2852 | { |
7835b98b | 2853 | unsigned long this_load; |
48f24c4d | 2854 | int i, scale; |
1da177e4 | 2855 | |
2dd73a4f | 2856 | this_load = this_rq->raw_weighted_load; |
48f24c4d IM |
2857 | |
2858 | /* Update our load: */ | |
2859 | for (i = 0, scale = 1; i < 3; i++, scale <<= 1) { | |
2860 | unsigned long old_load, new_load; | |
2861 | ||
7897986b | 2862 | old_load = this_rq->cpu_load[i]; |
48f24c4d | 2863 | new_load = this_load; |
7897986b NP |
2864 | /* |
2865 | * Round up the averaging division if load is increasing. This | |
2866 | * prevents us from getting stuck on 9 if the load is 10, for | |
2867 | * example. | |
2868 | */ | |
2869 | if (new_load > old_load) | |
2870 | new_load += scale-1; | |
2871 | this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale; | |
2872 | } | |
7835b98b CL |
2873 | } |
2874 | ||
2875 | /* | |
c9819f45 | 2876 | * run_rebalance_domains is triggered when needed from the scheduler tick. |
7835b98b CL |
2877 | * |
2878 | * It checks each scheduling domain to see if it is due to be balanced, | |
2879 | * and initiates a balancing operation if so. | |
2880 | * | |
2881 | * Balancing parameters are set up in arch_init_sched_domains. | |
2882 | */ | |
2883 | ||
c9819f45 | 2884 | static void run_rebalance_domains(struct softirq_action *h) |
7835b98b | 2885 | { |
c9819f45 CL |
2886 | int this_cpu = smp_processor_id(); |
2887 | struct rq *this_rq = cpu_rq(this_cpu); | |
7835b98b CL |
2888 | unsigned long interval; |
2889 | struct sched_domain *sd; | |
e418e1c2 CL |
2890 | /* |
2891 | * We are idle if there are no processes running. This | |
2892 | * is valid even if we are the idle process (SMT). | |
2893 | */ | |
2894 | enum idle_type idle = !this_rq->nr_running ? | |
2895 | SCHED_IDLE : NOT_IDLE; | |
c9819f45 CL |
2896 | /* Earliest time when we have to call run_rebalance_domains again */ |
2897 | unsigned long next_balance = jiffies + 60*HZ; | |
1da177e4 LT |
2898 | |
2899 | for_each_domain(this_cpu, sd) { | |
1da177e4 LT |
2900 | if (!(sd->flags & SD_LOAD_BALANCE)) |
2901 | continue; | |
2902 | ||
2903 | interval = sd->balance_interval; | |
2904 | if (idle != SCHED_IDLE) | |
2905 | interval *= sd->busy_factor; | |
2906 | ||
2907 | /* scale ms to jiffies */ | |
2908 | interval = msecs_to_jiffies(interval); | |
2909 | if (unlikely(!interval)) | |
2910 | interval = 1; | |
2911 | ||
c9819f45 | 2912 | if (time_after_eq(jiffies, sd->last_balance + interval)) { |
1da177e4 | 2913 | if (load_balance(this_cpu, this_rq, sd, idle)) { |
fa3b6ddc SS |
2914 | /* |
2915 | * We've pulled tasks over so either we're no | |
5969fe06 NP |
2916 | * longer idle, or one of our SMT siblings is |
2917 | * not idle. | |
2918 | */ | |
1da177e4 LT |
2919 | idle = NOT_IDLE; |
2920 | } | |
1bd77f2d | 2921 | sd->last_balance = jiffies; |
1da177e4 | 2922 | } |
c9819f45 CL |
2923 | if (time_after(next_balance, sd->last_balance + interval)) |
2924 | next_balance = sd->last_balance + interval; | |
1da177e4 | 2925 | } |
c9819f45 | 2926 | this_rq->next_balance = next_balance; |
1da177e4 LT |
2927 | } |
2928 | #else | |
2929 | /* | |
2930 | * on UP we do not need to balance between CPUs: | |
2931 | */ | |
70b97a7f | 2932 | static inline void idle_balance(int cpu, struct rq *rq) |
1da177e4 LT |
2933 | { |
2934 | } | |
2935 | #endif | |
2936 | ||
e418e1c2 | 2937 | static inline void wake_priority_sleeper(struct rq *rq) |
1da177e4 | 2938 | { |
1da177e4 | 2939 | #ifdef CONFIG_SCHED_SMT |
571f6d2f | 2940 | if (!rq->nr_running) |
e418e1c2 | 2941 | return; |
571f6d2f | 2942 | |
1da177e4 LT |
2943 | spin_lock(&rq->lock); |
2944 | /* | |
2945 | * If an SMT sibling task has been put to sleep for priority | |
2946 | * reasons reschedule the idle task to see if it can now run. | |
2947 | */ | |
e418e1c2 | 2948 | if (rq->nr_running) |
1da177e4 | 2949 | resched_task(rq->idle); |
1da177e4 LT |
2950 | spin_unlock(&rq->lock); |
2951 | #endif | |
1da177e4 LT |
2952 | } |
2953 | ||
2954 | DEFINE_PER_CPU(struct kernel_stat, kstat); | |
2955 | ||
2956 | EXPORT_PER_CPU_SYMBOL(kstat); | |
2957 | ||
2958 | /* | |
2959 | * This is called on clock ticks and on context switches. | |
2960 | * Bank in p->sched_time the ns elapsed since the last tick or switch. | |
2961 | */ | |
48f24c4d | 2962 | static inline void |
70b97a7f | 2963 | update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now) |
1da177e4 | 2964 | { |
48f24c4d | 2965 | p->sched_time += now - max(p->timestamp, rq->timestamp_last_tick); |
1da177e4 LT |
2966 | } |
2967 | ||
2968 | /* | |
2969 | * Return current->sched_time plus any more ns on the sched_clock | |
2970 | * that have not yet been banked. | |
2971 | */ | |
36c8b586 | 2972 | unsigned long long current_sched_time(const struct task_struct *p) |
1da177e4 LT |
2973 | { |
2974 | unsigned long long ns; | |
2975 | unsigned long flags; | |
48f24c4d | 2976 | |
1da177e4 | 2977 | local_irq_save(flags); |
48f24c4d IM |
2978 | ns = max(p->timestamp, task_rq(p)->timestamp_last_tick); |
2979 | ns = p->sched_time + sched_clock() - ns; | |
1da177e4 | 2980 | local_irq_restore(flags); |
48f24c4d | 2981 | |
1da177e4 LT |
2982 | return ns; |
2983 | } | |
2984 | ||
f1adad78 LT |
2985 | /* |
2986 | * We place interactive tasks back into the active array, if possible. | |
2987 | * | |
2988 | * To guarantee that this does not starve expired tasks we ignore the | |
2989 | * interactivity of a task if the first expired task had to wait more | |
2990 | * than a 'reasonable' amount of time. This deadline timeout is | |
2991 | * load-dependent, as the frequency of array switched decreases with | |
2992 | * increasing number of running tasks. We also ignore the interactivity | |
2993 | * if a better static_prio task has expired: | |
2994 | */ | |
70b97a7f | 2995 | static inline int expired_starving(struct rq *rq) |
48f24c4d IM |
2996 | { |
2997 | if (rq->curr->static_prio > rq->best_expired_prio) | |
2998 | return 1; | |
2999 | if (!STARVATION_LIMIT || !rq->expired_timestamp) | |
3000 | return 0; | |
3001 | if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running) | |
3002 | return 1; | |
3003 | return 0; | |
3004 | } | |
f1adad78 | 3005 | |
1da177e4 LT |
3006 | /* |
3007 | * Account user cpu time to a process. | |
3008 | * @p: the process that the cpu time gets accounted to | |
3009 | * @hardirq_offset: the offset to subtract from hardirq_count() | |
3010 | * @cputime: the cpu time spent in user space since the last update | |
3011 | */ | |
3012 | void account_user_time(struct task_struct *p, cputime_t cputime) | |
3013 | { | |
3014 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
3015 | cputime64_t tmp; | |
3016 | ||
3017 | p->utime = cputime_add(p->utime, cputime); | |
3018 | ||
3019 | /* Add user time to cpustat. */ | |
3020 | tmp = cputime_to_cputime64(cputime); | |
3021 | if (TASK_NICE(p) > 0) | |
3022 | cpustat->nice = cputime64_add(cpustat->nice, tmp); | |
3023 | else | |
3024 | cpustat->user = cputime64_add(cpustat->user, tmp); | |
3025 | } | |
3026 | ||
3027 | /* | |
3028 | * Account system cpu time to a process. | |
3029 | * @p: the process that the cpu time gets accounted to | |
3030 | * @hardirq_offset: the offset to subtract from hardirq_count() | |
3031 | * @cputime: the cpu time spent in kernel space since the last update | |
3032 | */ | |
3033 | void account_system_time(struct task_struct *p, int hardirq_offset, | |
3034 | cputime_t cputime) | |
3035 | { | |
3036 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
70b97a7f | 3037 | struct rq *rq = this_rq(); |
1da177e4 LT |
3038 | cputime64_t tmp; |
3039 | ||
3040 | p->stime = cputime_add(p->stime, cputime); | |
3041 | ||
3042 | /* Add system time to cpustat. */ | |
3043 | tmp = cputime_to_cputime64(cputime); | |
3044 | if (hardirq_count() - hardirq_offset) | |
3045 | cpustat->irq = cputime64_add(cpustat->irq, tmp); | |
3046 | else if (softirq_count()) | |
3047 | cpustat->softirq = cputime64_add(cpustat->softirq, tmp); | |
3048 | else if (p != rq->idle) | |
3049 | cpustat->system = cputime64_add(cpustat->system, tmp); | |
3050 | else if (atomic_read(&rq->nr_iowait) > 0) | |
3051 | cpustat->iowait = cputime64_add(cpustat->iowait, tmp); | |
3052 | else | |
3053 | cpustat->idle = cputime64_add(cpustat->idle, tmp); | |
3054 | /* Account for system time used */ | |
3055 | acct_update_integrals(p); | |
1da177e4 LT |
3056 | } |
3057 | ||
3058 | /* | |
3059 | * Account for involuntary wait time. | |
3060 | * @p: the process from which the cpu time has been stolen | |
3061 | * @steal: the cpu time spent in involuntary wait | |
3062 | */ | |
3063 | void account_steal_time(struct task_struct *p, cputime_t steal) | |
3064 | { | |
3065 | struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; | |
3066 | cputime64_t tmp = cputime_to_cputime64(steal); | |
70b97a7f | 3067 | struct rq *rq = this_rq(); |
1da177e4 LT |
3068 | |
3069 | if (p == rq->idle) { | |
3070 | p->stime = cputime_add(p->stime, steal); | |
3071 | if (atomic_read(&rq->nr_iowait) > 0) | |
3072 | cpustat->iowait = cputime64_add(cpustat->iowait, tmp); | |
3073 | else | |
3074 | cpustat->idle = cputime64_add(cpustat->idle, tmp); | |
3075 | } else | |
3076 | cpustat->steal = cputime64_add(cpustat->steal, tmp); | |
3077 | } | |
3078 | ||
7835b98b | 3079 | static void task_running_tick(struct rq *rq, struct task_struct *p) |
1da177e4 | 3080 | { |
1da177e4 | 3081 | if (p->array != rq->active) { |
7835b98b | 3082 | /* Task has expired but was not scheduled yet */ |
1da177e4 | 3083 | set_tsk_need_resched(p); |
7835b98b | 3084 | return; |
1da177e4 LT |
3085 | } |
3086 | spin_lock(&rq->lock); | |
3087 | /* | |
3088 | * The task was running during this tick - update the | |
3089 | * time slice counter. Note: we do not update a thread's | |
3090 | * priority until it either goes to sleep or uses up its | |
3091 | * timeslice. This makes it possible for interactive tasks | |
3092 | * to use up their timeslices at their highest priority levels. | |
3093 | */ | |
3094 | if (rt_task(p)) { | |
3095 | /* | |
3096 | * RR tasks need a special form of timeslice management. | |
3097 | * FIFO tasks have no timeslices. | |
3098 | */ | |
3099 | if ((p->policy == SCHED_RR) && !--p->time_slice) { | |
3100 | p->time_slice = task_timeslice(p); | |
3101 | p->first_time_slice = 0; | |
3102 | set_tsk_need_resched(p); | |
3103 | ||
3104 | /* put it at the end of the queue: */ | |
3105 | requeue_task(p, rq->active); | |
3106 | } | |
3107 | goto out_unlock; | |
3108 | } | |
3109 | if (!--p->time_slice) { | |
3110 | dequeue_task(p, rq->active); | |
3111 | set_tsk_need_resched(p); | |
3112 | p->prio = effective_prio(p); | |
3113 | p->time_slice = task_timeslice(p); | |
3114 | p->first_time_slice = 0; | |
3115 | ||
3116 | if (!rq->expired_timestamp) | |
3117 | rq->expired_timestamp = jiffies; | |
48f24c4d | 3118 | if (!TASK_INTERACTIVE(p) || expired_starving(rq)) { |
1da177e4 LT |
3119 | enqueue_task(p, rq->expired); |
3120 | if (p->static_prio < rq->best_expired_prio) | |
3121 | rq->best_expired_prio = p->static_prio; | |
3122 | } else | |
3123 | enqueue_task(p, rq->active); | |
3124 | } else { | |
3125 | /* | |
3126 | * Prevent a too long timeslice allowing a task to monopolize | |
3127 | * the CPU. We do this by splitting up the timeslice into | |
3128 | * smaller pieces. | |
3129 | * | |
3130 | * Note: this does not mean the task's timeslices expire or | |
3131 | * get lost in any way, they just might be preempted by | |
3132 | * another task of equal priority. (one with higher | |
3133 | * priority would have preempted this task already.) We | |
3134 | * requeue this task to the end of the list on this priority | |
3135 | * level, which is in essence a round-robin of tasks with | |
3136 | * equal priority. | |
3137 | * | |
3138 | * This only applies to tasks in the interactive | |
3139 | * delta range with at least TIMESLICE_GRANULARITY to requeue. | |
3140 | */ | |
3141 | if (TASK_INTERACTIVE(p) && !((task_timeslice(p) - | |
3142 | p->time_slice) % TIMESLICE_GRANULARITY(p)) && | |
3143 | (p->time_slice >= TIMESLICE_GRANULARITY(p)) && | |
3144 | (p->array == rq->active)) { | |
3145 | ||
3146 | requeue_task(p, rq->active); | |
3147 | set_tsk_need_resched(p); | |
3148 | } | |
3149 | } | |
3150 | out_unlock: | |
3151 | spin_unlock(&rq->lock); | |
7835b98b CL |
3152 | } |
3153 | ||
3154 | /* | |
3155 | * This function gets called by the timer code, with HZ frequency. | |
3156 | * We call it with interrupts disabled. | |
3157 | * | |
3158 | * It also gets called by the fork code, when changing the parent's | |
3159 | * timeslices. | |
3160 | */ | |
3161 | void scheduler_tick(void) | |
3162 | { | |
3163 | unsigned long long now = sched_clock(); | |
3164 | struct task_struct *p = current; | |
3165 | int cpu = smp_processor_id(); | |
3166 | struct rq *rq = cpu_rq(cpu); | |
7835b98b CL |
3167 | |
3168 | update_cpu_clock(p, rq, now); | |
3169 | ||
3170 | rq->timestamp_last_tick = now; | |
3171 | ||
e418e1c2 | 3172 | if (p == rq->idle) |
7835b98b | 3173 | /* Task on the idle queue */ |
e418e1c2 CL |
3174 | wake_priority_sleeper(rq); |
3175 | else | |
7835b98b | 3176 | task_running_tick(rq, p); |
e418e1c2 | 3177 | #ifdef CONFIG_SMP |
7835b98b | 3178 | update_load(rq); |
c9819f45 CL |
3179 | if (time_after_eq(jiffies, rq->next_balance)) |
3180 | raise_softirq(SCHED_SOFTIRQ); | |
e418e1c2 | 3181 | #endif |
1da177e4 LT |
3182 | } |
3183 | ||
3184 | #ifdef CONFIG_SCHED_SMT | |
70b97a7f | 3185 | static inline void wakeup_busy_runqueue(struct rq *rq) |
fc38ed75 CK |
3186 | { |
3187 | /* If an SMT runqueue is sleeping due to priority reasons wake it up */ | |
3188 | if (rq->curr == rq->idle && rq->nr_running) | |
3189 | resched_task(rq->idle); | |
3190 | } | |
3191 | ||
c96d145e KC |
3192 | /* |
3193 | * Called with interrupt disabled and this_rq's runqueue locked. | |
3194 | */ | |
3195 | static void wake_sleeping_dependent(int this_cpu) | |
1da177e4 | 3196 | { |
41c7ce9a | 3197 | struct sched_domain *tmp, *sd = NULL; |
1da177e4 LT |
3198 | int i; |
3199 | ||
c96d145e KC |
3200 | for_each_domain(this_cpu, tmp) { |
3201 | if (tmp->flags & SD_SHARE_CPUPOWER) { | |
41c7ce9a | 3202 | sd = tmp; |
c96d145e KC |
3203 | break; |
3204 | } | |
3205 | } | |
41c7ce9a NP |
3206 | |
3207 | if (!sd) | |
1da177e4 LT |
3208 | return; |
3209 | ||
c96d145e | 3210 | for_each_cpu_mask(i, sd->span) { |
70b97a7f | 3211 | struct rq *smt_rq = cpu_rq(i); |
1da177e4 | 3212 | |
c96d145e KC |
3213 | if (i == this_cpu) |
3214 | continue; | |
3215 | if (unlikely(!spin_trylock(&smt_rq->lock))) | |
3216 | continue; | |
3217 | ||
fc38ed75 | 3218 | wakeup_busy_runqueue(smt_rq); |
c96d145e | 3219 | spin_unlock(&smt_rq->lock); |
1da177e4 | 3220 | } |
1da177e4 LT |
3221 | } |
3222 | ||
67f9a619 IM |
3223 | /* |
3224 | * number of 'lost' timeslices this task wont be able to fully | |
3225 | * utilize, if another task runs on a sibling. This models the | |
3226 | * slowdown effect of other tasks running on siblings: | |
3227 | */ | |
36c8b586 IM |
3228 | static inline unsigned long |
3229 | smt_slice(struct task_struct *p, struct sched_domain *sd) | |
67f9a619 IM |
3230 | { |
3231 | return p->time_slice * (100 - sd->per_cpu_gain) / 100; | |
3232 | } | |
3233 | ||
c96d145e KC |
3234 | /* |
3235 | * To minimise lock contention and not have to drop this_rq's runlock we only | |
3236 | * trylock the sibling runqueues and bypass those runqueues if we fail to | |
3237 | * acquire their lock. As we only trylock the normal locking order does not | |
3238 | * need to be obeyed. | |
3239 | */ | |
36c8b586 | 3240 | static int |
70b97a7f | 3241 | dependent_sleeper(int this_cpu, struct rq *this_rq, struct task_struct *p) |
1da177e4 | 3242 | { |
41c7ce9a | 3243 | struct sched_domain *tmp, *sd = NULL; |
1da177e4 | 3244 | int ret = 0, i; |
1da177e4 | 3245 | |
c96d145e KC |
3246 | /* kernel/rt threads do not participate in dependent sleeping */ |
3247 | if (!p->mm || rt_task(p)) | |
3248 | return 0; | |
3249 | ||
3250 | for_each_domain(this_cpu, tmp) { | |
3251 | if (tmp->flags & SD_SHARE_CPUPOWER) { | |
41c7ce9a | 3252 | sd = tmp; |
c96d145e KC |
3253 | break; |
3254 | } | |
3255 | } | |
41c7ce9a NP |
3256 | |
3257 | if (!sd) | |
1da177e4 LT |
3258 | return 0; |
3259 | ||
c96d145e | 3260 | for_each_cpu_mask(i, sd->span) { |
36c8b586 | 3261 | struct task_struct *smt_curr; |
70b97a7f | 3262 | struct rq *smt_rq; |
1da177e4 | 3263 | |
c96d145e KC |
3264 | if (i == this_cpu) |
3265 | continue; | |
1da177e4 | 3266 | |
c96d145e KC |
3267 | smt_rq = cpu_rq(i); |
3268 | if (unlikely(!spin_trylock(&smt_rq->lock))) | |
3269 | continue; | |
1da177e4 | 3270 | |
c96d145e | 3271 | smt_curr = smt_rq->curr; |
1da177e4 | 3272 | |
c96d145e KC |
3273 | if (!smt_curr->mm) |
3274 | goto unlock; | |
fc38ed75 | 3275 | |
1da177e4 LT |
3276 | /* |
3277 | * If a user task with lower static priority than the | |
3278 | * running task on the SMT sibling is trying to schedule, | |
3279 | * delay it till there is proportionately less timeslice | |
3280 | * left of the sibling task to prevent a lower priority | |
3281 | * task from using an unfair proportion of the | |
3282 | * physical cpu's resources. -ck | |
3283 | */ | |
fc38ed75 CK |
3284 | if (rt_task(smt_curr)) { |
3285 | /* | |
3286 | * With real time tasks we run non-rt tasks only | |
3287 | * per_cpu_gain% of the time. | |
3288 | */ | |
3289 | if ((jiffies % DEF_TIMESLICE) > | |
3290 | (sd->per_cpu_gain * DEF_TIMESLICE / 100)) | |
3291 | ret = 1; | |
c96d145e | 3292 | } else { |
67f9a619 IM |
3293 | if (smt_curr->static_prio < p->static_prio && |
3294 | !TASK_PREEMPTS_CURR(p, smt_rq) && | |
3295 | smt_slice(smt_curr, sd) > task_timeslice(p)) | |
fc38ed75 | 3296 | ret = 1; |
fc38ed75 | 3297 | } |
c96d145e KC |
3298 | unlock: |
3299 | spin_unlock(&smt_rq->lock); | |
1da177e4 | 3300 | } |
1da177e4 LT |
3301 | return ret; |
3302 | } | |
3303 | #else | |
c96d145e | 3304 | static inline void wake_sleeping_dependent(int this_cpu) |
1da177e4 LT |
3305 | { |
3306 | } | |
48f24c4d | 3307 | static inline int |
70b97a7f | 3308 | dependent_sleeper(int this_cpu, struct rq *this_rq, struct task_struct *p) |
1da177e4 LT |
3309 | { |
3310 | return 0; | |
3311 | } | |
3312 | #endif | |
3313 | ||
3314 | #if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT) | |
3315 | ||
3316 | void fastcall add_preempt_count(int val) | |
3317 | { | |
3318 | /* | |
3319 | * Underflow? | |
3320 | */ | |
9a11b49a IM |
3321 | if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) |
3322 | return; | |
1da177e4 LT |
3323 | preempt_count() += val; |
3324 | /* | |
3325 | * Spinlock count overflowing soon? | |
3326 | */ | |
9a11b49a | 3327 | DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= PREEMPT_MASK-10); |
1da177e4 LT |
3328 | } |
3329 | EXPORT_SYMBOL(add_preempt_count); | |
3330 | ||
3331 | void fastcall sub_preempt_count(int val) | |
3332 | { | |
3333 | /* | |
3334 | * Underflow? | |
3335 | */ | |
9a11b49a IM |
3336 | if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) |
3337 | return; | |
1da177e4 LT |
3338 | /* |
3339 | * Is the spinlock portion underflowing? | |
3340 | */ | |
9a11b49a IM |
3341 | if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && |
3342 | !(preempt_count() & PREEMPT_MASK))) | |
3343 | return; | |
3344 | ||
1da177e4 LT |
3345 | preempt_count() -= val; |
3346 | } | |
3347 | EXPORT_SYMBOL(sub_preempt_count); | |
3348 | ||
3349 | #endif | |
3350 | ||
3dee386e CK |
3351 | static inline int interactive_sleep(enum sleep_type sleep_type) |
3352 | { | |
3353 | return (sleep_type == SLEEP_INTERACTIVE || | |
3354 | sleep_type == SLEEP_INTERRUPTED); | |
3355 | } | |
3356 | ||
1da177e4 LT |
3357 | /* |
3358 | * schedule() is the main scheduler function. | |
3359 | */ | |
3360 | asmlinkage void __sched schedule(void) | |
3361 | { | |
36c8b586 | 3362 | struct task_struct *prev, *next; |
70b97a7f | 3363 | struct prio_array *array; |
1da177e4 LT |
3364 | struct list_head *queue; |
3365 | unsigned long long now; | |
3366 | unsigned long run_time; | |
a3464a10 | 3367 | int cpu, idx, new_prio; |
48f24c4d | 3368 | long *switch_count; |
70b97a7f | 3369 | struct rq *rq; |
1da177e4 LT |
3370 | |
3371 | /* | |
3372 | * Test if we are atomic. Since do_exit() needs to call into | |
3373 | * schedule() atomically, we ignore that path for now. | |
3374 | * Otherwise, whine if we are scheduling when we should not be. | |
3375 | */ | |
77e4bfbc AM |
3376 | if (unlikely(in_atomic() && !current->exit_state)) { |
3377 | printk(KERN_ERR "BUG: scheduling while atomic: " | |
3378 | "%s/0x%08x/%d\n", | |
3379 | current->comm, preempt_count(), current->pid); | |
a4c410f0 | 3380 | debug_show_held_locks(current); |
77e4bfbc | 3381 | dump_stack(); |
1da177e4 LT |
3382 | } |
3383 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); | |
3384 | ||
3385 | need_resched: | |
3386 | preempt_disable(); | |
3387 | prev = current; | |
3388 | release_kernel_lock(prev); | |
3389 | need_resched_nonpreemptible: | |
3390 | rq = this_rq(); | |
3391 | ||
3392 | /* | |
3393 | * The idle thread is not allowed to schedule! | |
3394 | * Remove this check after it has been exercised a bit. | |
3395 | */ | |
3396 | if (unlikely(prev == rq->idle) && prev->state != TASK_RUNNING) { | |
3397 | printk(KERN_ERR "bad: scheduling from the idle thread!\n"); | |
3398 | dump_stack(); | |
3399 | } | |
3400 | ||
3401 | schedstat_inc(rq, sched_cnt); | |
3402 | now = sched_clock(); | |
238628ed | 3403 | if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) { |
1da177e4 | 3404 | run_time = now - prev->timestamp; |
238628ed | 3405 | if (unlikely((long long)(now - prev->timestamp) < 0)) |
1da177e4 LT |
3406 | run_time = 0; |
3407 | } else | |
3408 | run_time = NS_MAX_SLEEP_AVG; | |
3409 | ||
3410 | /* | |
3411 | * Tasks charged proportionately less run_time at high sleep_avg to | |
3412 | * delay them losing their interactive status | |
3413 | */ | |
3414 | run_time /= (CURRENT_BONUS(prev) ? : 1); | |
3415 | ||
3416 | spin_lock_irq(&rq->lock); | |
3417 | ||
1da177e4 LT |
3418 | switch_count = &prev->nivcsw; |
3419 | if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { | |
3420 | switch_count = &prev->nvcsw; | |
3421 | if (unlikely((prev->state & TASK_INTERRUPTIBLE) && | |
3422 | unlikely(signal_pending(prev)))) | |
3423 | prev->state = TASK_RUNNING; | |
3424 | else { | |
3425 | if (prev->state == TASK_UNINTERRUPTIBLE) | |
3426 | rq->nr_uninterruptible++; | |
3427 | deactivate_task(prev, rq); | |
3428 | } | |
3429 | } | |
3430 | ||
3431 | cpu = smp_processor_id(); | |
3432 | if (unlikely(!rq->nr_running)) { | |
1da177e4 LT |
3433 | idle_balance(cpu, rq); |
3434 | if (!rq->nr_running) { | |
3435 | next = rq->idle; | |
3436 | rq->expired_timestamp = 0; | |
c96d145e | 3437 | wake_sleeping_dependent(cpu); |
1da177e4 LT |
3438 | goto switch_tasks; |
3439 | } | |
1da177e4 LT |
3440 | } |
3441 | ||
3442 | array = rq->active; | |
3443 | if (unlikely(!array->nr_active)) { | |
3444 | /* | |
3445 | * Switch the active and expired arrays. | |
3446 | */ | |
3447 | schedstat_inc(rq, sched_switch); | |
3448 | rq->active = rq->expired; | |
3449 | rq->expired = array; | |
3450 | array = rq->active; | |
3451 | rq->expired_timestamp = 0; | |
3452 | rq->best_expired_prio = MAX_PRIO; | |
3453 | } | |
3454 | ||
3455 | idx = sched_find_first_bit(array->bitmap); | |
3456 | queue = array->queue + idx; | |
36c8b586 | 3457 | next = list_entry(queue->next, struct task_struct, run_list); |
1da177e4 | 3458 | |
3dee386e | 3459 | if (!rt_task(next) && interactive_sleep(next->sleep_type)) { |
1da177e4 | 3460 | unsigned long long delta = now - next->timestamp; |
238628ed | 3461 | if (unlikely((long long)(now - next->timestamp) < 0)) |
1da177e4 LT |
3462 | delta = 0; |
3463 | ||
3dee386e | 3464 | if (next->sleep_type == SLEEP_INTERACTIVE) |
1da177e4 LT |
3465 | delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128; |
3466 | ||
3467 | array = next->array; | |
a3464a10 CS |
3468 | new_prio = recalc_task_prio(next, next->timestamp + delta); |
3469 | ||
3470 | if (unlikely(next->prio != new_prio)) { | |
3471 | dequeue_task(next, array); | |
3472 | next->prio = new_prio; | |
3473 | enqueue_task(next, array); | |
7c4bb1f9 | 3474 | } |
1da177e4 | 3475 | } |
3dee386e | 3476 | next->sleep_type = SLEEP_NORMAL; |
c96d145e KC |
3477 | if (dependent_sleeper(cpu, rq, next)) |
3478 | next = rq->idle; | |
1da177e4 LT |
3479 | switch_tasks: |
3480 | if (next == rq->idle) | |
3481 | schedstat_inc(rq, sched_goidle); | |
3482 | prefetch(next); | |
383f2835 | 3483 | prefetch_stack(next); |
1da177e4 LT |
3484 | clear_tsk_need_resched(prev); |
3485 | rcu_qsctr_inc(task_cpu(prev)); | |
3486 | ||
3487 | update_cpu_clock(prev, rq, now); | |
3488 | ||
3489 | prev->sleep_avg -= run_time; | |
3490 | if ((long)prev->sleep_avg <= 0) | |
3491 | prev->sleep_avg = 0; | |
3492 | prev->timestamp = prev->last_ran = now; | |
3493 | ||
3494 | sched_info_switch(prev, next); | |
3495 | if (likely(prev != next)) { | |
3496 | next->timestamp = now; | |
3497 | rq->nr_switches++; | |
3498 | rq->curr = next; | |
3499 | ++*switch_count; | |
3500 | ||
4866cde0 | 3501 | prepare_task_switch(rq, next); |
1da177e4 LT |
3502 | prev = context_switch(rq, prev, next); |
3503 | barrier(); | |
4866cde0 NP |
3504 | /* |
3505 | * this_rq must be evaluated again because prev may have moved | |
3506 | * CPUs since it called schedule(), thus the 'rq' on its stack | |
3507 | * frame will be invalid. | |
3508 | */ | |
3509 | finish_task_switch(this_rq(), prev); | |
1da177e4 LT |
3510 | } else |
3511 | spin_unlock_irq(&rq->lock); | |
3512 | ||
3513 | prev = current; | |
3514 | if (unlikely(reacquire_kernel_lock(prev) < 0)) | |
3515 | goto need_resched_nonpreemptible; | |
3516 | preempt_enable_no_resched(); | |
3517 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
3518 | goto need_resched; | |
3519 | } | |
1da177e4 LT |
3520 | EXPORT_SYMBOL(schedule); |
3521 | ||
3522 | #ifdef CONFIG_PREEMPT | |
3523 | /* | |
2ed6e34f | 3524 | * this is the entry point to schedule() from in-kernel preemption |
1da177e4 LT |
3525 | * off of preempt_enable. Kernel preemptions off return from interrupt |
3526 | * occur there and call schedule directly. | |
3527 | */ | |
3528 | asmlinkage void __sched preempt_schedule(void) | |
3529 | { | |
3530 | struct thread_info *ti = current_thread_info(); | |
3531 | #ifdef CONFIG_PREEMPT_BKL | |
3532 | struct task_struct *task = current; | |
3533 | int saved_lock_depth; | |
3534 | #endif | |
3535 | /* | |
3536 | * If there is a non-zero preempt_count or interrupts are disabled, | |
3537 | * we do not want to preempt the current task. Just return.. | |
3538 | */ | |
beed33a8 | 3539 | if (likely(ti->preempt_count || irqs_disabled())) |
1da177e4 LT |
3540 | return; |
3541 | ||
3542 | need_resched: | |
3543 | add_preempt_count(PREEMPT_ACTIVE); | |
3544 | /* | |
3545 | * We keep the big kernel semaphore locked, but we | |
3546 | * clear ->lock_depth so that schedule() doesnt | |
3547 | * auto-release the semaphore: | |
3548 | */ | |
3549 | #ifdef CONFIG_PREEMPT_BKL | |
3550 | saved_lock_depth = task->lock_depth; | |
3551 | task->lock_depth = -1; | |
3552 | #endif | |
3553 | schedule(); | |
3554 | #ifdef CONFIG_PREEMPT_BKL | |
3555 | task->lock_depth = saved_lock_depth; | |
3556 | #endif | |
3557 | sub_preempt_count(PREEMPT_ACTIVE); | |
3558 | ||
3559 | /* we could miss a preemption opportunity between schedule and now */ | |
3560 | barrier(); | |
3561 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
3562 | goto need_resched; | |
3563 | } | |
1da177e4 LT |
3564 | EXPORT_SYMBOL(preempt_schedule); |
3565 | ||
3566 | /* | |
2ed6e34f | 3567 | * this is the entry point to schedule() from kernel preemption |
1da177e4 LT |
3568 | * off of irq context. |
3569 | * Note, that this is called and return with irqs disabled. This will | |
3570 | * protect us against recursive calling from irq. | |
3571 | */ | |
3572 | asmlinkage void __sched preempt_schedule_irq(void) | |
3573 | { | |
3574 | struct thread_info *ti = current_thread_info(); | |
3575 | #ifdef CONFIG_PREEMPT_BKL | |
3576 | struct task_struct *task = current; | |
3577 | int saved_lock_depth; | |
3578 | #endif | |
2ed6e34f | 3579 | /* Catch callers which need to be fixed */ |
1da177e4 LT |
3580 | BUG_ON(ti->preempt_count || !irqs_disabled()); |
3581 | ||
3582 | need_resched: | |
3583 | add_preempt_count(PREEMPT_ACTIVE); | |
3584 | /* | |
3585 | * We keep the big kernel semaphore locked, but we | |
3586 | * clear ->lock_depth so that schedule() doesnt | |
3587 | * auto-release the semaphore: | |
3588 | */ | |
3589 | #ifdef CONFIG_PREEMPT_BKL | |
3590 | saved_lock_depth = task->lock_depth; | |
3591 | task->lock_depth = -1; | |
3592 | #endif | |
3593 | local_irq_enable(); | |
3594 | schedule(); | |
3595 | local_irq_disable(); | |
3596 | #ifdef CONFIG_PREEMPT_BKL | |
3597 | task->lock_depth = saved_lock_depth; | |
3598 | #endif | |
3599 | sub_preempt_count(PREEMPT_ACTIVE); | |
3600 | ||
3601 | /* we could miss a preemption opportunity between schedule and now */ | |
3602 | barrier(); | |
3603 | if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) | |
3604 | goto need_resched; | |
3605 | } | |
3606 | ||
3607 | #endif /* CONFIG_PREEMPT */ | |
3608 | ||
95cdf3b7 IM |
3609 | int default_wake_function(wait_queue_t *curr, unsigned mode, int sync, |
3610 | void *key) | |
1da177e4 | 3611 | { |
48f24c4d | 3612 | return try_to_wake_up(curr->private, mode, sync); |
1da177e4 | 3613 | } |
1da177e4 LT |
3614 | EXPORT_SYMBOL(default_wake_function); |
3615 | ||
3616 | /* | |
3617 | * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just | |
3618 | * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve | |
3619 | * number) then we wake all the non-exclusive tasks and one exclusive task. | |
3620 | * | |
3621 | * There are circumstances in which we can try to wake a task which has already | |
3622 | * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns | |
3623 | * zero in this (rare) case, and we handle it by continuing to scan the queue. | |
3624 | */ | |
3625 | static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, | |
3626 | int nr_exclusive, int sync, void *key) | |
3627 | { | |
3628 | struct list_head *tmp, *next; | |
3629 | ||
3630 | list_for_each_safe(tmp, next, &q->task_list) { | |
48f24c4d IM |
3631 | wait_queue_t *curr = list_entry(tmp, wait_queue_t, task_list); |
3632 | unsigned flags = curr->flags; | |
3633 | ||
1da177e4 | 3634 | if (curr->func(curr, mode, sync, key) && |
48f24c4d | 3635 | (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) |
1da177e4 LT |
3636 | break; |
3637 | } | |
3638 | } | |
3639 | ||
3640 | /** | |
3641 | * __wake_up - wake up threads blocked on a waitqueue. | |
3642 | * @q: the waitqueue | |
3643 | * @mode: which threads | |
3644 | * @nr_exclusive: how many wake-one or wake-many threads to wake up | |
67be2dd1 | 3645 | * @key: is directly passed to the wakeup function |
1da177e4 LT |
3646 | */ |
3647 | void fastcall __wake_up(wait_queue_head_t *q, unsigned int mode, | |
95cdf3b7 | 3648 | int nr_exclusive, void *key) |
1da177e4 LT |
3649 | { |
3650 | unsigned long flags; | |
3651 | ||
3652 | spin_lock_irqsave(&q->lock, flags); | |
3653 | __wake_up_common(q, mode, nr_exclusive, 0, key); | |
3654 | spin_unlock_irqrestore(&q->lock, flags); | |
3655 | } | |
1da177e4 LT |
3656 | EXPORT_SYMBOL(__wake_up); |
3657 | ||
3658 | /* | |
3659 | * Same as __wake_up but called with the spinlock in wait_queue_head_t held. | |
3660 | */ | |
3661 | void fastcall __wake_up_locked(wait_queue_head_t *q, unsigned int mode) | |
3662 | { | |
3663 | __wake_up_common(q, mode, 1, 0, NULL); | |
3664 | } | |
3665 | ||
3666 | /** | |
67be2dd1 | 3667 | * __wake_up_sync - wake up threads blocked on a waitqueue. |
1da177e4 LT |
3668 | * @q: the waitqueue |
3669 | * @mode: which threads | |
3670 | * @nr_exclusive: how many wake-one or wake-many threads to wake up | |
3671 | * | |
3672 | * The sync wakeup differs that the waker knows that it will schedule | |
3673 | * away soon, so while the target thread will be woken up, it will not | |
3674 | * be migrated to another CPU - ie. the two threads are 'synchronized' | |
3675 | * with each other. This can prevent needless bouncing between CPUs. | |
3676 | * | |
3677 | * On UP it can prevent extra preemption. | |
3678 | */ | |
95cdf3b7 IM |
3679 | void fastcall |
3680 | __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) | |
1da177e4 LT |
3681 | { |
3682 | unsigned long flags; | |
3683 | int sync = 1; | |
3684 | ||
3685 | if (unlikely(!q)) | |
3686 | return; | |
3687 | ||
3688 | if (unlikely(!nr_exclusive)) | |
3689 | sync = 0; | |
3690 | ||
3691 | spin_lock_irqsave(&q->lock, flags); | |
3692 | __wake_up_common(q, mode, nr_exclusive, sync, NULL); | |
3693 | spin_unlock_irqrestore(&q->lock, flags); | |
3694 | } | |
3695 | EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ | |
3696 | ||
3697 | void fastcall complete(struct completion *x) | |
3698 | { | |
3699 | unsigned long flags; | |
3700 | ||
3701 | spin_lock_irqsave(&x->wait.lock, flags); | |
3702 | x->done++; | |
3703 | __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, | |
3704 | 1, 0, NULL); | |
3705 | spin_unlock_irqrestore(&x->wait.lock, flags); | |
3706 | } | |
3707 | EXPORT_SYMBOL(complete); | |
3708 | ||
3709 | void fastcall complete_all(struct completion *x) | |
3710 | { | |
3711 | unsigned long flags; | |
3712 | ||
3713 | spin_lock_irqsave(&x->wait.lock, flags); | |
3714 | x->done += UINT_MAX/2; | |
3715 | __wake_up_common(&x->wait, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, | |
3716 | 0, 0, NULL); | |
3717 | spin_unlock_irqrestore(&x->wait.lock, flags); | |
3718 | } | |
3719 | EXPORT_SYMBOL(complete_all); | |
3720 | ||
3721 | void fastcall __sched wait_for_completion(struct completion *x) | |
3722 | { | |
3723 | might_sleep(); | |
48f24c4d | 3724 | |
1da177e4 LT |
3725 | spin_lock_irq(&x->wait.lock); |
3726 | if (!x->done) { | |
3727 | DECLARE_WAITQUEUE(wait, current); | |
3728 | ||
3729 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3730 | __add_wait_queue_tail(&x->wait, &wait); | |
3731 | do { | |
3732 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
3733 | spin_unlock_irq(&x->wait.lock); | |
3734 | schedule(); | |
3735 | spin_lock_irq(&x->wait.lock); | |
3736 | } while (!x->done); | |
3737 | __remove_wait_queue(&x->wait, &wait); | |
3738 | } | |
3739 | x->done--; | |
3740 | spin_unlock_irq(&x->wait.lock); | |
3741 | } | |
3742 | EXPORT_SYMBOL(wait_for_completion); | |
3743 | ||
3744 | unsigned long fastcall __sched | |
3745 | wait_for_completion_timeout(struct completion *x, unsigned long timeout) | |
3746 | { | |
3747 | might_sleep(); | |
3748 | ||
3749 | spin_lock_irq(&x->wait.lock); | |
3750 | if (!x->done) { | |
3751 | DECLARE_WAITQUEUE(wait, current); | |
3752 | ||
3753 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3754 | __add_wait_queue_tail(&x->wait, &wait); | |
3755 | do { | |
3756 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
3757 | spin_unlock_irq(&x->wait.lock); | |
3758 | timeout = schedule_timeout(timeout); | |
3759 | spin_lock_irq(&x->wait.lock); | |
3760 | if (!timeout) { | |
3761 | __remove_wait_queue(&x->wait, &wait); | |
3762 | goto out; | |
3763 | } | |
3764 | } while (!x->done); | |
3765 | __remove_wait_queue(&x->wait, &wait); | |
3766 | } | |
3767 | x->done--; | |
3768 | out: | |
3769 | spin_unlock_irq(&x->wait.lock); | |
3770 | return timeout; | |
3771 | } | |
3772 | EXPORT_SYMBOL(wait_for_completion_timeout); | |
3773 | ||
3774 | int fastcall __sched wait_for_completion_interruptible(struct completion *x) | |
3775 | { | |
3776 | int ret = 0; | |
3777 | ||
3778 | might_sleep(); | |
3779 | ||
3780 | spin_lock_irq(&x->wait.lock); | |
3781 | if (!x->done) { | |
3782 | DECLARE_WAITQUEUE(wait, current); | |
3783 | ||
3784 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3785 | __add_wait_queue_tail(&x->wait, &wait); | |
3786 | do { | |
3787 | if (signal_pending(current)) { | |
3788 | ret = -ERESTARTSYS; | |
3789 | __remove_wait_queue(&x->wait, &wait); | |
3790 | goto out; | |
3791 | } | |
3792 | __set_current_state(TASK_INTERRUPTIBLE); | |
3793 | spin_unlock_irq(&x->wait.lock); | |
3794 | schedule(); | |
3795 | spin_lock_irq(&x->wait.lock); | |
3796 | } while (!x->done); | |
3797 | __remove_wait_queue(&x->wait, &wait); | |
3798 | } | |
3799 | x->done--; | |
3800 | out: | |
3801 | spin_unlock_irq(&x->wait.lock); | |
3802 | ||
3803 | return ret; | |
3804 | } | |
3805 | EXPORT_SYMBOL(wait_for_completion_interruptible); | |
3806 | ||
3807 | unsigned long fastcall __sched | |
3808 | wait_for_completion_interruptible_timeout(struct completion *x, | |
3809 | unsigned long timeout) | |
3810 | { | |
3811 | might_sleep(); | |
3812 | ||
3813 | spin_lock_irq(&x->wait.lock); | |
3814 | if (!x->done) { | |
3815 | DECLARE_WAITQUEUE(wait, current); | |
3816 | ||
3817 | wait.flags |= WQ_FLAG_EXCLUSIVE; | |
3818 | __add_wait_queue_tail(&x->wait, &wait); | |
3819 | do { | |
3820 | if (signal_pending(current)) { | |
3821 | timeout = -ERESTARTSYS; | |
3822 | __remove_wait_queue(&x->wait, &wait); | |
3823 | goto out; | |
3824 | } | |
3825 | __set_current_state(TASK_INTERRUPTIBLE); | |
3826 | spin_unlock_irq(&x->wait.lock); | |
3827 | timeout = schedule_timeout(timeout); | |
3828 | spin_lock_irq(&x->wait.lock); | |
3829 | if (!timeout) { | |
3830 | __remove_wait_queue(&x->wait, &wait); | |
3831 | goto out; | |
3832 | } | |
3833 | } while (!x->done); | |
3834 | __remove_wait_queue(&x->wait, &wait); | |
3835 | } | |
3836 | x->done--; | |
3837 | out: | |
3838 | spin_unlock_irq(&x->wait.lock); | |
3839 | return timeout; | |
3840 | } | |
3841 | EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); | |
3842 | ||
3843 | ||
3844 | #define SLEEP_ON_VAR \ | |
3845 | unsigned long flags; \ | |
3846 | wait_queue_t wait; \ | |
3847 | init_waitqueue_entry(&wait, current); | |
3848 | ||
3849 | #define SLEEP_ON_HEAD \ | |
3850 | spin_lock_irqsave(&q->lock,flags); \ | |
3851 | __add_wait_queue(q, &wait); \ | |
3852 | spin_unlock(&q->lock); | |
3853 | ||
3854 | #define SLEEP_ON_TAIL \ | |
3855 | spin_lock_irq(&q->lock); \ | |
3856 | __remove_wait_queue(q, &wait); \ | |
3857 | spin_unlock_irqrestore(&q->lock, flags); | |
3858 | ||
3859 | void fastcall __sched interruptible_sleep_on(wait_queue_head_t *q) | |
3860 | { | |
3861 | SLEEP_ON_VAR | |
3862 | ||
3863 | current->state = TASK_INTERRUPTIBLE; | |
3864 | ||
3865 | SLEEP_ON_HEAD | |
3866 | schedule(); | |
3867 | SLEEP_ON_TAIL | |
3868 | } | |
1da177e4 LT |
3869 | EXPORT_SYMBOL(interruptible_sleep_on); |
3870 | ||
95cdf3b7 IM |
3871 | long fastcall __sched |
3872 | interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) | |
1da177e4 LT |
3873 | { |
3874 | SLEEP_ON_VAR | |
3875 | ||
3876 | current->state = TASK_INTERRUPTIBLE; | |
3877 | ||
3878 | SLEEP_ON_HEAD | |
3879 | timeout = schedule_timeout(timeout); | |
3880 | SLEEP_ON_TAIL | |
3881 | ||
3882 | return timeout; | |
3883 | } | |
1da177e4 LT |
3884 | EXPORT_SYMBOL(interruptible_sleep_on_timeout); |
3885 | ||
3886 | void fastcall __sched sleep_on(wait_queue_head_t *q) | |
3887 | { | |
3888 | SLEEP_ON_VAR | |
3889 | ||
3890 | current->state = TASK_UNINTERRUPTIBLE; | |
3891 | ||
3892 | SLEEP_ON_HEAD | |
3893 | schedule(); | |
3894 | SLEEP_ON_TAIL | |
3895 | } | |
1da177e4 LT |
3896 | EXPORT_SYMBOL(sleep_on); |
3897 | ||
3898 | long fastcall __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) | |
3899 | { | |
3900 | SLEEP_ON_VAR | |
3901 | ||
3902 | current->state = TASK_UNINTERRUPTIBLE; | |
3903 | ||
3904 | SLEEP_ON_HEAD | |
3905 | timeout = schedule_timeout(timeout); | |
3906 | SLEEP_ON_TAIL | |
3907 | ||
3908 | return timeout; | |
3909 | } | |
3910 | ||
3911 | EXPORT_SYMBOL(sleep_on_timeout); | |
3912 | ||
b29739f9 IM |
3913 | #ifdef CONFIG_RT_MUTEXES |
3914 | ||
3915 | /* | |
3916 | * rt_mutex_setprio - set the current priority of a task | |
3917 | * @p: task | |
3918 | * @prio: prio value (kernel-internal form) | |
3919 | * | |
3920 | * This function changes the 'effective' priority of a task. It does | |
3921 | * not touch ->normal_prio like __setscheduler(). | |
3922 | * | |
3923 | * Used by the rt_mutex code to implement priority inheritance logic. | |
3924 | */ | |
36c8b586 | 3925 | void rt_mutex_setprio(struct task_struct *p, int prio) |
b29739f9 | 3926 | { |
70b97a7f | 3927 | struct prio_array *array; |
b29739f9 | 3928 | unsigned long flags; |
70b97a7f | 3929 | struct rq *rq; |
b29739f9 IM |
3930 | int oldprio; |
3931 | ||
3932 | BUG_ON(prio < 0 || prio > MAX_PRIO); | |
3933 | ||
3934 | rq = task_rq_lock(p, &flags); | |
3935 | ||
3936 | oldprio = p->prio; | |
3937 | array = p->array; | |
3938 | if (array) | |
3939 | dequeue_task(p, array); | |
3940 | p->prio = prio; | |
3941 | ||
3942 | if (array) { | |
3943 | /* | |
3944 | * If changing to an RT priority then queue it | |
3945 | * in the active array! | |
3946 | */ | |
3947 | if (rt_task(p)) | |
3948 | array = rq->active; | |
3949 | enqueue_task(p, array); | |
3950 | /* | |
3951 | * Reschedule if we are currently running on this runqueue and | |
3952 | * our priority decreased, or if we are not currently running on | |
3953 | * this runqueue and our priority is higher than the current's | |
3954 | */ | |
3955 | if (task_running(rq, p)) { | |
3956 | if (p->prio > oldprio) | |
3957 | resched_task(rq->curr); | |
3958 | } else if (TASK_PREEMPTS_CURR(p, rq)) | |
3959 | resched_task(rq->curr); | |
3960 | } | |
3961 | task_rq_unlock(rq, &flags); | |
3962 | } | |
3963 | ||
3964 | #endif | |
3965 | ||
36c8b586 | 3966 | void set_user_nice(struct task_struct *p, long nice) |
1da177e4 | 3967 | { |
70b97a7f | 3968 | struct prio_array *array; |
48f24c4d | 3969 | int old_prio, delta; |
1da177e4 | 3970 | unsigned long flags; |
70b97a7f | 3971 | struct rq *rq; |
1da177e4 LT |
3972 | |
3973 | if (TASK_NICE(p) == nice || nice < -20 || nice > 19) | |
3974 | return; | |
3975 | /* | |
3976 | * We have to be careful, if called from sys_setpriority(), | |
3977 | * the task might be in the middle of scheduling on another CPU. | |
3978 | */ | |
3979 | rq = task_rq_lock(p, &flags); | |
3980 | /* | |
3981 | * The RT priorities are set via sched_setscheduler(), but we still | |
3982 | * allow the 'normal' nice value to be set - but as expected | |
3983 | * it wont have any effect on scheduling until the task is | |
b0a9499c | 3984 | * not SCHED_NORMAL/SCHED_BATCH: |
1da177e4 | 3985 | */ |
b29739f9 | 3986 | if (has_rt_policy(p)) { |
1da177e4 LT |
3987 | p->static_prio = NICE_TO_PRIO(nice); |
3988 | goto out_unlock; | |
3989 | } | |
3990 | array = p->array; | |
2dd73a4f | 3991 | if (array) { |
1da177e4 | 3992 | dequeue_task(p, array); |
2dd73a4f PW |
3993 | dec_raw_weighted_load(rq, p); |
3994 | } | |
1da177e4 | 3995 | |
1da177e4 | 3996 | p->static_prio = NICE_TO_PRIO(nice); |
2dd73a4f | 3997 | set_load_weight(p); |
b29739f9 IM |
3998 | old_prio = p->prio; |
3999 | p->prio = effective_prio(p); | |
4000 | delta = p->prio - old_prio; | |
1da177e4 LT |
4001 | |
4002 | if (array) { | |
4003 | enqueue_task(p, array); | |
2dd73a4f | 4004 | inc_raw_weighted_load(rq, p); |
1da177e4 LT |
4005 | /* |
4006 | * If the task increased its priority or is running and | |
4007 | * lowered its priority, then reschedule its CPU: | |
4008 | */ | |
4009 | if (delta < 0 || (delta > 0 && task_running(rq, p))) | |
4010 | resched_task(rq->curr); | |
4011 | } | |
4012 | out_unlock: | |
4013 | task_rq_unlock(rq, &flags); | |
4014 | } | |
1da177e4 LT |
4015 | EXPORT_SYMBOL(set_user_nice); |
4016 | ||
e43379f1 MM |
4017 | /* |
4018 | * can_nice - check if a task can reduce its nice value | |
4019 | * @p: task | |
4020 | * @nice: nice value | |
4021 | */ | |
36c8b586 | 4022 | int can_nice(const struct task_struct *p, const int nice) |
e43379f1 | 4023 | { |
024f4747 MM |
4024 | /* convert nice value [19,-20] to rlimit style value [1,40] */ |
4025 | int nice_rlim = 20 - nice; | |
48f24c4d | 4026 | |
e43379f1 MM |
4027 | return (nice_rlim <= p->signal->rlim[RLIMIT_NICE].rlim_cur || |
4028 | capable(CAP_SYS_NICE)); | |
4029 | } | |
4030 | ||
1da177e4 LT |
4031 | #ifdef __ARCH_WANT_SYS_NICE |
4032 | ||
4033 | /* | |
4034 | * sys_nice - change the priority of the current process. | |
4035 | * @increment: priority increment | |
4036 | * | |
4037 | * sys_setpriority is a more generic, but much slower function that | |
4038 | * does similar things. | |
4039 | */ | |
4040 | asmlinkage long sys_nice(int increment) | |
4041 | { | |
48f24c4d | 4042 | long nice, retval; |
1da177e4 LT |
4043 | |
4044 | /* | |
4045 | * Setpriority might change our priority at the same moment. | |
4046 | * We don't have to worry. Conceptually one call occurs first | |
4047 | * and we have a single winner. | |
4048 | */ | |
e43379f1 MM |
4049 | if (increment < -40) |
4050 | increment = -40; | |
1da177e4 LT |
4051 | if (increment > 40) |
4052 | increment = 40; | |
4053 | ||
4054 | nice = PRIO_TO_NICE(current->static_prio) + increment; | |
4055 | if (nice < -20) | |
4056 | nice = -20; | |
4057 | if (nice > 19) | |
4058 | nice = 19; | |
4059 | ||
e43379f1 MM |
4060 | if (increment < 0 && !can_nice(current, nice)) |
4061 | return -EPERM; | |
4062 | ||
1da177e4 LT |
4063 | retval = security_task_setnice(current, nice); |
4064 | if (retval) | |
4065 | return retval; | |
4066 | ||
4067 | set_user_nice(current, nice); | |
4068 | return 0; | |
4069 | } | |
4070 | ||
4071 | #endif | |
4072 | ||
4073 | /** | |
4074 | * task_prio - return the priority value of a given task. | |
4075 | * @p: the task in question. | |
4076 | * | |
4077 | * This is the priority value as seen by users in /proc. | |
4078 | * RT tasks are offset by -200. Normal tasks are centered | |
4079 | * around 0, value goes from -16 to +15. | |
4080 | */ | |
36c8b586 | 4081 | int task_prio(const struct task_struct *p) |
1da177e4 LT |
4082 | { |
4083 | return p->prio - MAX_RT_PRIO; | |
4084 | } | |
4085 | ||
4086 | /** | |
4087 | * task_nice - return the nice value of a given task. | |
4088 | * @p: the task in question. | |
4089 | */ | |
36c8b586 | 4090 | int task_nice(const struct task_struct *p) |
1da177e4 LT |
4091 | { |
4092 | return TASK_NICE(p); | |
4093 | } | |
1da177e4 | 4094 | EXPORT_SYMBOL_GPL(task_nice); |
1da177e4 LT |
4095 | |
4096 | /** | |
4097 | * idle_cpu - is a given cpu idle currently? | |
4098 | * @cpu: the processor in question. | |
4099 | */ | |
4100 | int idle_cpu(int cpu) | |
4101 | { | |
4102 | return cpu_curr(cpu) == cpu_rq(cpu)->idle; | |
4103 | } | |
4104 | ||
1da177e4 LT |
4105 | /** |
4106 | * idle_task - return the idle task for a given cpu. | |
4107 | * @cpu: the processor in question. | |
4108 | */ | |
36c8b586 | 4109 | struct task_struct *idle_task(int cpu) |
1da177e4 LT |
4110 | { |
4111 | return cpu_rq(cpu)->idle; | |
4112 | } | |
4113 | ||
4114 | /** | |
4115 | * find_process_by_pid - find a process with a matching PID value. | |
4116 | * @pid: the pid in question. | |
4117 | */ | |
36c8b586 | 4118 | static inline struct task_struct *find_process_by_pid(pid_t pid) |
1da177e4 LT |
4119 | { |
4120 | return pid ? find_task_by_pid(pid) : current; | |
4121 | } | |
4122 | ||
4123 | /* Actually do priority change: must hold rq lock. */ | |
4124 | static void __setscheduler(struct task_struct *p, int policy, int prio) | |
4125 | { | |
4126 | BUG_ON(p->array); | |
48f24c4d | 4127 | |
1da177e4 LT |
4128 | p->policy = policy; |
4129 | p->rt_priority = prio; | |
b29739f9 IM |
4130 | p->normal_prio = normal_prio(p); |
4131 | /* we are holding p->pi_lock already */ | |
4132 | p->prio = rt_mutex_getprio(p); | |
4133 | /* | |
4134 | * SCHED_BATCH tasks are treated as perpetual CPU hogs: | |
4135 | */ | |
4136 | if (policy == SCHED_BATCH) | |
4137 | p->sleep_avg = 0; | |
2dd73a4f | 4138 | set_load_weight(p); |
1da177e4 LT |
4139 | } |
4140 | ||
4141 | /** | |
4142 | * sched_setscheduler - change the scheduling policy and/or RT priority of | |
4143 | * a thread. | |
4144 | * @p: the task in question. | |
4145 | * @policy: new policy. | |
4146 | * @param: structure containing the new RT priority. | |
5fe1d75f ON |
4147 | * |
4148 | * NOTE: the task may be already dead | |
1da177e4 | 4149 | */ |
95cdf3b7 IM |
4150 | int sched_setscheduler(struct task_struct *p, int policy, |
4151 | struct sched_param *param) | |
1da177e4 | 4152 | { |
48f24c4d | 4153 | int retval, oldprio, oldpolicy = -1; |
70b97a7f | 4154 | struct prio_array *array; |
1da177e4 | 4155 | unsigned long flags; |
70b97a7f | 4156 | struct rq *rq; |
1da177e4 | 4157 | |
66e5393a SR |
4158 | /* may grab non-irq protected spin_locks */ |
4159 | BUG_ON(in_interrupt()); | |
1da177e4 LT |
4160 | recheck: |
4161 | /* double check policy once rq lock held */ | |
4162 | if (policy < 0) | |
4163 | policy = oldpolicy = p->policy; | |
4164 | else if (policy != SCHED_FIFO && policy != SCHED_RR && | |
b0a9499c IM |
4165 | policy != SCHED_NORMAL && policy != SCHED_BATCH) |
4166 | return -EINVAL; | |
1da177e4 LT |
4167 | /* |
4168 | * Valid priorities for SCHED_FIFO and SCHED_RR are | |
b0a9499c IM |
4169 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL and |
4170 | * SCHED_BATCH is 0. | |
1da177e4 LT |
4171 | */ |
4172 | if (param->sched_priority < 0 || | |
95cdf3b7 | 4173 | (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || |
d46523ea | 4174 | (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) |
1da177e4 | 4175 | return -EINVAL; |
57a6f51c | 4176 | if (is_rt_policy(policy) != (param->sched_priority != 0)) |
1da177e4 LT |
4177 | return -EINVAL; |
4178 | ||
37e4ab3f OC |
4179 | /* |
4180 | * Allow unprivileged RT tasks to decrease priority: | |
4181 | */ | |
4182 | if (!capable(CAP_SYS_NICE)) { | |
8dc3e909 ON |
4183 | if (is_rt_policy(policy)) { |
4184 | unsigned long rlim_rtprio; | |
4185 | unsigned long flags; | |
4186 | ||
4187 | if (!lock_task_sighand(p, &flags)) | |
4188 | return -ESRCH; | |
4189 | rlim_rtprio = p->signal->rlim[RLIMIT_RTPRIO].rlim_cur; | |
4190 | unlock_task_sighand(p, &flags); | |
4191 | ||
4192 | /* can't set/change the rt policy */ | |
4193 | if (policy != p->policy && !rlim_rtprio) | |
4194 | return -EPERM; | |
4195 | ||
4196 | /* can't increase priority */ | |
4197 | if (param->sched_priority > p->rt_priority && | |
4198 | param->sched_priority > rlim_rtprio) | |
4199 | return -EPERM; | |
4200 | } | |
5fe1d75f | 4201 | |
37e4ab3f OC |
4202 | /* can't change other user's priorities */ |
4203 | if ((current->euid != p->euid) && | |
4204 | (current->euid != p->uid)) | |
4205 | return -EPERM; | |
4206 | } | |
1da177e4 LT |
4207 | |
4208 | retval = security_task_setscheduler(p, policy, param); | |
4209 | if (retval) | |
4210 | return retval; | |
b29739f9 IM |
4211 | /* |
4212 | * make sure no PI-waiters arrive (or leave) while we are | |
4213 | * changing the priority of the task: | |
4214 | */ | |
4215 | spin_lock_irqsave(&p->pi_lock, flags); | |
1da177e4 LT |
4216 | /* |
4217 | * To be able to change p->policy safely, the apropriate | |
4218 | * runqueue lock must be held. | |
4219 | */ | |
b29739f9 | 4220 | rq = __task_rq_lock(p); |
1da177e4 LT |
4221 | /* recheck policy now with rq lock held */ |
4222 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { | |
4223 | policy = oldpolicy = -1; | |
b29739f9 IM |
4224 | __task_rq_unlock(rq); |
4225 | spin_unlock_irqrestore(&p->pi_lock, flags); | |
1da177e4 LT |
4226 | goto recheck; |
4227 | } | |
4228 | array = p->array; | |
4229 | if (array) | |
4230 | deactivate_task(p, rq); | |
4231 | oldprio = p->prio; | |
4232 | __setscheduler(p, policy, param->sched_priority); | |
4233 | if (array) { | |
4234 | __activate_task(p, rq); | |
4235 | /* | |
4236 | * Reschedule if we are currently running on this runqueue and | |
4237 | * our priority decreased, or if we are not currently running on | |
4238 | * this runqueue and our priority is higher than the current's | |
4239 | */ | |
4240 | if (task_running(rq, p)) { | |
4241 | if (p->prio > oldprio) | |
4242 | resched_task(rq->curr); | |
4243 | } else if (TASK_PREEMPTS_CURR(p, rq)) | |
4244 | resched_task(rq->curr); | |
4245 | } | |
b29739f9 IM |
4246 | __task_rq_unlock(rq); |
4247 | spin_unlock_irqrestore(&p->pi_lock, flags); | |
4248 | ||
95e02ca9 TG |
4249 | rt_mutex_adjust_pi(p); |
4250 | ||
1da177e4 LT |
4251 | return 0; |
4252 | } | |
4253 | EXPORT_SYMBOL_GPL(sched_setscheduler); | |
4254 | ||
95cdf3b7 IM |
4255 | static int |
4256 | do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) | |
1da177e4 | 4257 | { |
1da177e4 LT |
4258 | struct sched_param lparam; |
4259 | struct task_struct *p; | |
36c8b586 | 4260 | int retval; |
1da177e4 LT |
4261 | |
4262 | if (!param || pid < 0) | |
4263 | return -EINVAL; | |
4264 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) | |
4265 | return -EFAULT; | |
5fe1d75f ON |
4266 | |
4267 | rcu_read_lock(); | |
4268 | retval = -ESRCH; | |
1da177e4 | 4269 | p = find_process_by_pid(pid); |
5fe1d75f ON |
4270 | if (p != NULL) |
4271 | retval = sched_setscheduler(p, policy, &lparam); | |
4272 | rcu_read_unlock(); | |
36c8b586 | 4273 | |
1da177e4 LT |
4274 | return retval; |
4275 | } | |
4276 | ||
4277 | /** | |
4278 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority | |
4279 | * @pid: the pid in question. | |
4280 | * @policy: new policy. | |
4281 | * @param: structure containing the new RT priority. | |
4282 | */ | |
4283 | asmlinkage long sys_sched_setscheduler(pid_t pid, int policy, | |
4284 | struct sched_param __user *param) | |
4285 | { | |
c21761f1 JB |
4286 | /* negative values for policy are not valid */ |
4287 | if (policy < 0) | |
4288 | return -EINVAL; | |
4289 | ||
1da177e4 LT |
4290 | return do_sched_setscheduler(pid, policy, param); |
4291 | } | |
4292 | ||
4293 | /** | |
4294 | * sys_sched_setparam - set/change the RT priority of a thread | |
4295 | * @pid: the pid in question. | |
4296 | * @param: structure containing the new RT priority. | |
4297 | */ | |
4298 | asmlinkage long sys_sched_setparam(pid_t pid, struct sched_param __user *param) | |
4299 | { | |
4300 | return do_sched_setscheduler(pid, -1, param); | |
4301 | } | |
4302 | ||
4303 | /** | |
4304 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread | |
4305 | * @pid: the pid in question. | |
4306 | */ | |
4307 | asmlinkage long sys_sched_getscheduler(pid_t pid) | |
4308 | { | |
36c8b586 | 4309 | struct task_struct *p; |
1da177e4 | 4310 | int retval = -EINVAL; |
1da177e4 LT |
4311 | |
4312 | if (pid < 0) | |
4313 | goto out_nounlock; | |
4314 | ||
4315 | retval = -ESRCH; | |
4316 | read_lock(&tasklist_lock); | |
4317 | p = find_process_by_pid(pid); | |
4318 | if (p) { | |
4319 | retval = security_task_getscheduler(p); | |
4320 | if (!retval) | |
4321 | retval = p->policy; | |
4322 | } | |
4323 | read_unlock(&tasklist_lock); | |
4324 | ||
4325 | out_nounlock: | |
4326 | return retval; | |
4327 | } | |
4328 | ||
4329 | /** | |
4330 | * sys_sched_getscheduler - get the RT priority of a thread | |
4331 | * @pid: the pid in question. | |
4332 | * @param: structure containing the RT priority. | |
4333 | */ | |
4334 | asmlinkage long sys_sched_getparam(pid_t pid, struct sched_param __user *param) | |
4335 | { | |
4336 | struct sched_param lp; | |
36c8b586 | 4337 | struct task_struct *p; |
1da177e4 | 4338 | int retval = -EINVAL; |
1da177e4 LT |
4339 | |
4340 | if (!param || pid < 0) | |
4341 | goto out_nounlock; | |
4342 | ||
4343 | read_lock(&tasklist_lock); | |
4344 | p = find_process_by_pid(pid); | |
4345 | retval = -ESRCH; | |
4346 | if (!p) | |
4347 | goto out_unlock; | |
4348 | ||
4349 | retval = security_task_getscheduler(p); | |
4350 | if (retval) | |
4351 | goto out_unlock; | |
4352 | ||
4353 | lp.sched_priority = p->rt_priority; | |
4354 | read_unlock(&tasklist_lock); | |
4355 | ||
4356 | /* | |
4357 | * This one might sleep, we cannot do it with a spinlock held ... | |
4358 | */ | |
4359 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; | |
4360 | ||
4361 | out_nounlock: | |
4362 | return retval; | |
4363 | ||
4364 | out_unlock: | |
4365 | read_unlock(&tasklist_lock); | |
4366 | return retval; | |
4367 | } | |
4368 | ||
4369 | long sched_setaffinity(pid_t pid, cpumask_t new_mask) | |
4370 | { | |
1da177e4 | 4371 | cpumask_t cpus_allowed; |
36c8b586 IM |
4372 | struct task_struct *p; |
4373 | int retval; | |
1da177e4 LT |
4374 | |
4375 | lock_cpu_hotplug(); | |
4376 | read_lock(&tasklist_lock); | |
4377 | ||
4378 | p = find_process_by_pid(pid); | |
4379 | if (!p) { | |
4380 | read_unlock(&tasklist_lock); | |
4381 | unlock_cpu_hotplug(); | |
4382 | return -ESRCH; | |
4383 | } | |
4384 | ||
4385 | /* | |
4386 | * It is not safe to call set_cpus_allowed with the | |
4387 | * tasklist_lock held. We will bump the task_struct's | |
4388 | * usage count and then drop tasklist_lock. | |
4389 | */ | |
4390 | get_task_struct(p); | |
4391 | read_unlock(&tasklist_lock); | |
4392 | ||
4393 | retval = -EPERM; | |
4394 | if ((current->euid != p->euid) && (current->euid != p->uid) && | |
4395 | !capable(CAP_SYS_NICE)) | |
4396 | goto out_unlock; | |
4397 | ||
e7834f8f DQ |
4398 | retval = security_task_setscheduler(p, 0, NULL); |
4399 | if (retval) | |
4400 | goto out_unlock; | |
4401 | ||
1da177e4 LT |
4402 | cpus_allowed = cpuset_cpus_allowed(p); |
4403 | cpus_and(new_mask, new_mask, cpus_allowed); | |
4404 | retval = set_cpus_allowed(p, new_mask); | |
4405 | ||
4406 | out_unlock: | |
4407 | put_task_struct(p); | |
4408 | unlock_cpu_hotplug(); | |
4409 | return retval; | |
4410 | } | |
4411 | ||
4412 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, | |
4413 | cpumask_t *new_mask) | |
4414 | { | |
4415 | if (len < sizeof(cpumask_t)) { | |
4416 | memset(new_mask, 0, sizeof(cpumask_t)); | |
4417 | } else if (len > sizeof(cpumask_t)) { | |
4418 | len = sizeof(cpumask_t); | |
4419 | } | |
4420 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; | |
4421 | } | |
4422 | ||
4423 | /** | |
4424 | * sys_sched_setaffinity - set the cpu affinity of a process | |
4425 | * @pid: pid of the process | |
4426 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
4427 | * @user_mask_ptr: user-space pointer to the new cpu mask | |
4428 | */ | |
4429 | asmlinkage long sys_sched_setaffinity(pid_t pid, unsigned int len, | |
4430 | unsigned long __user *user_mask_ptr) | |
4431 | { | |
4432 | cpumask_t new_mask; | |
4433 | int retval; | |
4434 | ||
4435 | retval = get_user_cpu_mask(user_mask_ptr, len, &new_mask); | |
4436 | if (retval) | |
4437 | return retval; | |
4438 | ||
4439 | return sched_setaffinity(pid, new_mask); | |
4440 | } | |
4441 | ||
4442 | /* | |
4443 | * Represents all cpu's present in the system | |
4444 | * In systems capable of hotplug, this map could dynamically grow | |
4445 | * as new cpu's are detected in the system via any platform specific | |
4446 | * method, such as ACPI for e.g. | |
4447 | */ | |
4448 | ||
4cef0c61 | 4449 | cpumask_t cpu_present_map __read_mostly; |
1da177e4 LT |
4450 | EXPORT_SYMBOL(cpu_present_map); |
4451 | ||
4452 | #ifndef CONFIG_SMP | |
4cef0c61 | 4453 | cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL; |
e16b38f7 GB |
4454 | EXPORT_SYMBOL(cpu_online_map); |
4455 | ||
4cef0c61 | 4456 | cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL; |
e16b38f7 | 4457 | EXPORT_SYMBOL(cpu_possible_map); |
1da177e4 LT |
4458 | #endif |
4459 | ||
4460 | long sched_getaffinity(pid_t pid, cpumask_t *mask) | |
4461 | { | |
36c8b586 | 4462 | struct task_struct *p; |
1da177e4 | 4463 | int retval; |
1da177e4 LT |
4464 | |
4465 | lock_cpu_hotplug(); | |
4466 | read_lock(&tasklist_lock); | |
4467 | ||
4468 | retval = -ESRCH; | |
4469 | p = find_process_by_pid(pid); | |
4470 | if (!p) | |
4471 | goto out_unlock; | |
4472 | ||
e7834f8f DQ |
4473 | retval = security_task_getscheduler(p); |
4474 | if (retval) | |
4475 | goto out_unlock; | |
4476 | ||
2f7016d9 | 4477 | cpus_and(*mask, p->cpus_allowed, cpu_online_map); |
1da177e4 LT |
4478 | |
4479 | out_unlock: | |
4480 | read_unlock(&tasklist_lock); | |
4481 | unlock_cpu_hotplug(); | |
4482 | if (retval) | |
4483 | return retval; | |
4484 | ||
4485 | return 0; | |
4486 | } | |
4487 | ||
4488 | /** | |
4489 | * sys_sched_getaffinity - get the cpu affinity of a process | |
4490 | * @pid: pid of the process | |
4491 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
4492 | * @user_mask_ptr: user-space pointer to hold the current cpu mask | |
4493 | */ | |
4494 | asmlinkage long sys_sched_getaffinity(pid_t pid, unsigned int len, | |
4495 | unsigned long __user *user_mask_ptr) | |
4496 | { | |
4497 | int ret; | |
4498 | cpumask_t mask; | |
4499 | ||
4500 | if (len < sizeof(cpumask_t)) | |
4501 | return -EINVAL; | |
4502 | ||
4503 | ret = sched_getaffinity(pid, &mask); | |
4504 | if (ret < 0) | |
4505 | return ret; | |
4506 | ||
4507 | if (copy_to_user(user_mask_ptr, &mask, sizeof(cpumask_t))) | |
4508 | return -EFAULT; | |
4509 | ||
4510 | return sizeof(cpumask_t); | |
4511 | } | |
4512 | ||
4513 | /** | |
4514 | * sys_sched_yield - yield the current processor to other threads. | |
4515 | * | |
4516 | * this function yields the current CPU by moving the calling thread | |
4517 | * to the expired array. If there are no other threads running on this | |
4518 | * CPU then this function will return. | |
4519 | */ | |
4520 | asmlinkage long sys_sched_yield(void) | |
4521 | { | |
70b97a7f IM |
4522 | struct rq *rq = this_rq_lock(); |
4523 | struct prio_array *array = current->array, *target = rq->expired; | |
1da177e4 LT |
4524 | |
4525 | schedstat_inc(rq, yld_cnt); | |
4526 | /* | |
4527 | * We implement yielding by moving the task into the expired | |
4528 | * queue. | |
4529 | * | |
4530 | * (special rule: RT tasks will just roundrobin in the active | |
4531 | * array.) | |
4532 | */ | |
4533 | if (rt_task(current)) | |
4534 | target = rq->active; | |
4535 | ||
5927ad78 | 4536 | if (array->nr_active == 1) { |
1da177e4 LT |
4537 | schedstat_inc(rq, yld_act_empty); |
4538 | if (!rq->expired->nr_active) | |
4539 | schedstat_inc(rq, yld_both_empty); | |
4540 | } else if (!rq->expired->nr_active) | |
4541 | schedstat_inc(rq, yld_exp_empty); | |
4542 | ||
4543 | if (array != target) { | |
4544 | dequeue_task(current, array); | |
4545 | enqueue_task(current, target); | |
4546 | } else | |
4547 | /* | |
4548 | * requeue_task is cheaper so perform that if possible. | |
4549 | */ | |
4550 | requeue_task(current, array); | |
4551 | ||
4552 | /* | |
4553 | * Since we are going to call schedule() anyway, there's | |
4554 | * no need to preempt or enable interrupts: | |
4555 | */ | |
4556 | __release(rq->lock); | |
8a25d5de | 4557 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); |
1da177e4 LT |
4558 | _raw_spin_unlock(&rq->lock); |
4559 | preempt_enable_no_resched(); | |
4560 | ||
4561 | schedule(); | |
4562 | ||
4563 | return 0; | |
4564 | } | |
4565 | ||
2d7d2535 | 4566 | static inline int __resched_legal(int expected_preempt_count) |
e7b38404 | 4567 | { |
2d7d2535 | 4568 | if (unlikely(preempt_count() != expected_preempt_count)) |
e7b38404 AM |
4569 | return 0; |
4570 | if (unlikely(system_state != SYSTEM_RUNNING)) | |
4571 | return 0; | |
4572 | return 1; | |
4573 | } | |
4574 | ||
4575 | static void __cond_resched(void) | |
1da177e4 | 4576 | { |
8e0a43d8 IM |
4577 | #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP |
4578 | __might_sleep(__FILE__, __LINE__); | |
4579 | #endif | |
5bbcfd90 IM |
4580 | /* |
4581 | * The BKS might be reacquired before we have dropped | |
4582 | * PREEMPT_ACTIVE, which could trigger a second | |
4583 | * cond_resched() call. | |
4584 | */ | |
1da177e4 LT |
4585 | do { |
4586 | add_preempt_count(PREEMPT_ACTIVE); | |
4587 | schedule(); | |
4588 | sub_preempt_count(PREEMPT_ACTIVE); | |
4589 | } while (need_resched()); | |
4590 | } | |
4591 | ||
4592 | int __sched cond_resched(void) | |
4593 | { | |
2d7d2535 | 4594 | if (need_resched() && __resched_legal(0)) { |
1da177e4 LT |
4595 | __cond_resched(); |
4596 | return 1; | |
4597 | } | |
4598 | return 0; | |
4599 | } | |
1da177e4 LT |
4600 | EXPORT_SYMBOL(cond_resched); |
4601 | ||
4602 | /* | |
4603 | * cond_resched_lock() - if a reschedule is pending, drop the given lock, | |
4604 | * call schedule, and on return reacquire the lock. | |
4605 | * | |
4606 | * This works OK both with and without CONFIG_PREEMPT. We do strange low-level | |
4607 | * operations here to prevent schedule() from being called twice (once via | |
4608 | * spin_unlock(), once by hand). | |
4609 | */ | |
95cdf3b7 | 4610 | int cond_resched_lock(spinlock_t *lock) |
1da177e4 | 4611 | { |
6df3cecb JK |
4612 | int ret = 0; |
4613 | ||
1da177e4 LT |
4614 | if (need_lockbreak(lock)) { |
4615 | spin_unlock(lock); | |
4616 | cpu_relax(); | |
6df3cecb | 4617 | ret = 1; |
1da177e4 LT |
4618 | spin_lock(lock); |
4619 | } | |
2d7d2535 | 4620 | if (need_resched() && __resched_legal(1)) { |
8a25d5de | 4621 | spin_release(&lock->dep_map, 1, _THIS_IP_); |
1da177e4 LT |
4622 | _raw_spin_unlock(lock); |
4623 | preempt_enable_no_resched(); | |
4624 | __cond_resched(); | |
6df3cecb | 4625 | ret = 1; |
1da177e4 | 4626 | spin_lock(lock); |
1da177e4 | 4627 | } |
6df3cecb | 4628 | return ret; |
1da177e4 | 4629 | } |
1da177e4 LT |
4630 | EXPORT_SYMBOL(cond_resched_lock); |
4631 | ||
4632 | int __sched cond_resched_softirq(void) | |
4633 | { | |
4634 | BUG_ON(!in_softirq()); | |
4635 | ||
2d7d2535 | 4636 | if (need_resched() && __resched_legal(0)) { |
de30a2b3 IM |
4637 | raw_local_irq_disable(); |
4638 | _local_bh_enable(); | |
4639 | raw_local_irq_enable(); | |
1da177e4 LT |
4640 | __cond_resched(); |
4641 | local_bh_disable(); | |
4642 | return 1; | |
4643 | } | |
4644 | return 0; | |
4645 | } | |
1da177e4 LT |
4646 | EXPORT_SYMBOL(cond_resched_softirq); |
4647 | ||
1da177e4 LT |
4648 | /** |
4649 | * yield - yield the current processor to other threads. | |
4650 | * | |
4651 | * this is a shortcut for kernel-space yielding - it marks the | |
4652 | * thread runnable and calls sys_sched_yield(). | |
4653 | */ | |
4654 | void __sched yield(void) | |
4655 | { | |
4656 | set_current_state(TASK_RUNNING); | |
4657 | sys_sched_yield(); | |
4658 | } | |
1da177e4 LT |
4659 | EXPORT_SYMBOL(yield); |
4660 | ||
4661 | /* | |
4662 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so | |
4663 | * that process accounting knows that this is a task in IO wait state. | |
4664 | * | |
4665 | * But don't do that if it is a deliberate, throttling IO wait (this task | |
4666 | * has set its backing_dev_info: the queue against which it should throttle) | |
4667 | */ | |
4668 | void __sched io_schedule(void) | |
4669 | { | |
70b97a7f | 4670 | struct rq *rq = &__raw_get_cpu_var(runqueues); |
1da177e4 | 4671 | |
0ff92245 | 4672 | delayacct_blkio_start(); |
1da177e4 LT |
4673 | atomic_inc(&rq->nr_iowait); |
4674 | schedule(); | |
4675 | atomic_dec(&rq->nr_iowait); | |
0ff92245 | 4676 | delayacct_blkio_end(); |
1da177e4 | 4677 | } |
1da177e4 LT |
4678 | EXPORT_SYMBOL(io_schedule); |
4679 | ||
4680 | long __sched io_schedule_timeout(long timeout) | |
4681 | { | |
70b97a7f | 4682 | struct rq *rq = &__raw_get_cpu_var(runqueues); |
1da177e4 LT |
4683 | long ret; |
4684 | ||
0ff92245 | 4685 | delayacct_blkio_start(); |
1da177e4 LT |
4686 | atomic_inc(&rq->nr_iowait); |
4687 | ret = schedule_timeout(timeout); | |
4688 | atomic_dec(&rq->nr_iowait); | |
0ff92245 | 4689 | delayacct_blkio_end(); |
1da177e4 LT |
4690 | return ret; |
4691 | } | |
4692 | ||
4693 | /** | |
4694 | * sys_sched_get_priority_max - return maximum RT priority. | |
4695 | * @policy: scheduling class. | |
4696 | * | |
4697 | * this syscall returns the maximum rt_priority that can be used | |
4698 | * by a given scheduling class. | |
4699 | */ | |
4700 | asmlinkage long sys_sched_get_priority_max(int policy) | |
4701 | { | |
4702 | int ret = -EINVAL; | |
4703 | ||
4704 | switch (policy) { | |
4705 | case SCHED_FIFO: | |
4706 | case SCHED_RR: | |
4707 | ret = MAX_USER_RT_PRIO-1; | |
4708 | break; | |
4709 | case SCHED_NORMAL: | |
b0a9499c | 4710 | case SCHED_BATCH: |
1da177e4 LT |
4711 | ret = 0; |
4712 | break; | |
4713 | } | |
4714 | return ret; | |
4715 | } | |
4716 | ||
4717 | /** | |
4718 | * sys_sched_get_priority_min - return minimum RT priority. | |
4719 | * @policy: scheduling class. | |
4720 | * | |
4721 | * this syscall returns the minimum rt_priority that can be used | |
4722 | * by a given scheduling class. | |
4723 | */ | |
4724 | asmlinkage long sys_sched_get_priority_min(int policy) | |
4725 | { | |
4726 | int ret = -EINVAL; | |
4727 | ||
4728 | switch (policy) { | |
4729 | case SCHED_FIFO: | |
4730 | case SCHED_RR: | |
4731 | ret = 1; | |
4732 | break; | |
4733 | case SCHED_NORMAL: | |
b0a9499c | 4734 | case SCHED_BATCH: |
1da177e4 LT |
4735 | ret = 0; |
4736 | } | |
4737 | return ret; | |
4738 | } | |
4739 | ||
4740 | /** | |
4741 | * sys_sched_rr_get_interval - return the default timeslice of a process. | |
4742 | * @pid: pid of the process. | |
4743 | * @interval: userspace pointer to the timeslice value. | |
4744 | * | |
4745 | * this syscall writes the default timeslice value of a given process | |
4746 | * into the user-space timespec buffer. A value of '0' means infinity. | |
4747 | */ | |
4748 | asmlinkage | |
4749 | long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval) | |
4750 | { | |
36c8b586 | 4751 | struct task_struct *p; |
1da177e4 LT |
4752 | int retval = -EINVAL; |
4753 | struct timespec t; | |
1da177e4 LT |
4754 | |
4755 | if (pid < 0) | |
4756 | goto out_nounlock; | |
4757 | ||
4758 | retval = -ESRCH; | |
4759 | read_lock(&tasklist_lock); | |
4760 | p = find_process_by_pid(pid); | |
4761 | if (!p) | |
4762 | goto out_unlock; | |
4763 | ||
4764 | retval = security_task_getscheduler(p); | |
4765 | if (retval) | |
4766 | goto out_unlock; | |
4767 | ||
b78709cf | 4768 | jiffies_to_timespec(p->policy == SCHED_FIFO ? |
1da177e4 LT |
4769 | 0 : task_timeslice(p), &t); |
4770 | read_unlock(&tasklist_lock); | |
4771 | retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; | |
4772 | out_nounlock: | |
4773 | return retval; | |
4774 | out_unlock: | |
4775 | read_unlock(&tasklist_lock); | |
4776 | return retval; | |
4777 | } | |
4778 | ||
4779 | static inline struct task_struct *eldest_child(struct task_struct *p) | |
4780 | { | |
48f24c4d IM |
4781 | if (list_empty(&p->children)) |
4782 | return NULL; | |
1da177e4 LT |
4783 | return list_entry(p->children.next,struct task_struct,sibling); |
4784 | } | |
4785 | ||
4786 | static inline struct task_struct *older_sibling(struct task_struct *p) | |
4787 | { | |
48f24c4d IM |
4788 | if (p->sibling.prev==&p->parent->children) |
4789 | return NULL; | |
1da177e4 LT |
4790 | return list_entry(p->sibling.prev,struct task_struct,sibling); |
4791 | } | |
4792 | ||
4793 | static inline struct task_struct *younger_sibling(struct task_struct *p) | |
4794 | { | |
48f24c4d IM |
4795 | if (p->sibling.next==&p->parent->children) |
4796 | return NULL; | |
1da177e4 LT |
4797 | return list_entry(p->sibling.next,struct task_struct,sibling); |
4798 | } | |
4799 | ||
2ed6e34f | 4800 | static const char stat_nam[] = "RSDTtZX"; |
36c8b586 IM |
4801 | |
4802 | static void show_task(struct task_struct *p) | |
1da177e4 | 4803 | { |
36c8b586 | 4804 | struct task_struct *relative; |
1da177e4 | 4805 | unsigned long free = 0; |
36c8b586 | 4806 | unsigned state; |
1da177e4 | 4807 | |
1da177e4 | 4808 | state = p->state ? __ffs(p->state) + 1 : 0; |
2ed6e34f AM |
4809 | printk("%-13.13s %c", p->comm, |
4810 | state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); | |
1da177e4 LT |
4811 | #if (BITS_PER_LONG == 32) |
4812 | if (state == TASK_RUNNING) | |
4813 | printk(" running "); | |
4814 | else | |
4815 | printk(" %08lX ", thread_saved_pc(p)); | |
4816 | #else | |
4817 | if (state == TASK_RUNNING) | |
4818 | printk(" running task "); | |
4819 | else | |
4820 | printk(" %016lx ", thread_saved_pc(p)); | |
4821 | #endif | |
4822 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
4823 | { | |
10ebffde | 4824 | unsigned long *n = end_of_stack(p); |
1da177e4 LT |
4825 | while (!*n) |
4826 | n++; | |
10ebffde | 4827 | free = (unsigned long)n - (unsigned long)end_of_stack(p); |
1da177e4 LT |
4828 | } |
4829 | #endif | |
4830 | printk("%5lu %5d %6d ", free, p->pid, p->parent->pid); | |
4831 | if ((relative = eldest_child(p))) | |
4832 | printk("%5d ", relative->pid); | |
4833 | else | |
4834 | printk(" "); | |
4835 | if ((relative = younger_sibling(p))) | |
4836 | printk("%7d", relative->pid); | |
4837 | else | |
4838 | printk(" "); | |
4839 | if ((relative = older_sibling(p))) | |
4840 | printk(" %5d", relative->pid); | |
4841 | else | |
4842 | printk(" "); | |
4843 | if (!p->mm) | |
4844 | printk(" (L-TLB)\n"); | |
4845 | else | |
4846 | printk(" (NOTLB)\n"); | |
4847 | ||
4848 | if (state != TASK_RUNNING) | |
4849 | show_stack(p, NULL); | |
4850 | } | |
4851 | ||
e59e2ae2 | 4852 | void show_state_filter(unsigned long state_filter) |
1da177e4 | 4853 | { |
36c8b586 | 4854 | struct task_struct *g, *p; |
1da177e4 LT |
4855 | |
4856 | #if (BITS_PER_LONG == 32) | |
4857 | printk("\n" | |
301827ac CC |
4858 | " free sibling\n"); |
4859 | printk(" task PC stack pid father child younger older\n"); | |
1da177e4 LT |
4860 | #else |
4861 | printk("\n" | |
301827ac CC |
4862 | " free sibling\n"); |
4863 | printk(" task PC stack pid father child younger older\n"); | |
1da177e4 LT |
4864 | #endif |
4865 | read_lock(&tasklist_lock); | |
4866 | do_each_thread(g, p) { | |
4867 | /* | |
4868 | * reset the NMI-timeout, listing all files on a slow | |
4869 | * console might take alot of time: | |
4870 | */ | |
4871 | touch_nmi_watchdog(); | |
e59e2ae2 IM |
4872 | if (p->state & state_filter) |
4873 | show_task(p); | |
1da177e4 LT |
4874 | } while_each_thread(g, p); |
4875 | ||
4876 | read_unlock(&tasklist_lock); | |
e59e2ae2 IM |
4877 | /* |
4878 | * Only show locks if all tasks are dumped: | |
4879 | */ | |
4880 | if (state_filter == -1) | |
4881 | debug_show_all_locks(); | |
1da177e4 LT |
4882 | } |
4883 | ||
f340c0d1 IM |
4884 | /** |
4885 | * init_idle - set up an idle thread for a given CPU | |
4886 | * @idle: task in question | |
4887 | * @cpu: cpu the idle task belongs to | |
4888 | * | |
4889 | * NOTE: this function does not set the idle thread's NEED_RESCHED | |
4890 | * flag, to make booting more robust. | |
4891 | */ | |
5c1e1767 | 4892 | void __cpuinit init_idle(struct task_struct *idle, int cpu) |
1da177e4 | 4893 | { |
70b97a7f | 4894 | struct rq *rq = cpu_rq(cpu); |
1da177e4 LT |
4895 | unsigned long flags; |
4896 | ||
81c29a85 | 4897 | idle->timestamp = sched_clock(); |
1da177e4 LT |
4898 | idle->sleep_avg = 0; |
4899 | idle->array = NULL; | |
b29739f9 | 4900 | idle->prio = idle->normal_prio = MAX_PRIO; |
1da177e4 LT |
4901 | idle->state = TASK_RUNNING; |
4902 | idle->cpus_allowed = cpumask_of_cpu(cpu); | |
4903 | set_task_cpu(idle, cpu); | |
4904 | ||
4905 | spin_lock_irqsave(&rq->lock, flags); | |
4906 | rq->curr = rq->idle = idle; | |
4866cde0 NP |
4907 | #if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) |
4908 | idle->oncpu = 1; | |
4909 | #endif | |
1da177e4 LT |
4910 | spin_unlock_irqrestore(&rq->lock, flags); |
4911 | ||
4912 | /* Set the preempt count _outside_ the spinlocks! */ | |
4913 | #if defined(CONFIG_PREEMPT) && !defined(CONFIG_PREEMPT_BKL) | |
a1261f54 | 4914 | task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0); |
1da177e4 | 4915 | #else |
a1261f54 | 4916 | task_thread_info(idle)->preempt_count = 0; |
1da177e4 LT |
4917 | #endif |
4918 | } | |
4919 | ||
4920 | /* | |
4921 | * In a system that switches off the HZ timer nohz_cpu_mask | |
4922 | * indicates which cpus entered this state. This is used | |
4923 | * in the rcu update to wait only for active cpus. For system | |
4924 | * which do not switch off the HZ timer nohz_cpu_mask should | |
4925 | * always be CPU_MASK_NONE. | |
4926 | */ | |
4927 | cpumask_t nohz_cpu_mask = CPU_MASK_NONE; | |
4928 | ||
4929 | #ifdef CONFIG_SMP | |
4930 | /* | |
4931 | * This is how migration works: | |
4932 | * | |
70b97a7f | 4933 | * 1) we queue a struct migration_req structure in the source CPU's |
1da177e4 LT |
4934 | * runqueue and wake up that CPU's migration thread. |
4935 | * 2) we down() the locked semaphore => thread blocks. | |
4936 | * 3) migration thread wakes up (implicitly it forces the migrated | |
4937 | * thread off the CPU) | |
4938 | * 4) it gets the migration request and checks whether the migrated | |
4939 | * task is still in the wrong runqueue. | |
4940 | * 5) if it's in the wrong runqueue then the migration thread removes | |
4941 | * it and puts it into the right queue. | |
4942 | * 6) migration thread up()s the semaphore. | |
4943 | * 7) we wake up and the migration is done. | |
4944 | */ | |
4945 | ||
4946 | /* | |
4947 | * Change a given task's CPU affinity. Migrate the thread to a | |
4948 | * proper CPU and schedule it away if the CPU it's executing on | |
4949 | * is removed from the allowed bitmask. | |
4950 | * | |
4951 | * NOTE: the caller must have a valid reference to the task, the | |
4952 | * task must not exit() & deallocate itself prematurely. The | |
4953 | * call is not atomic; no spinlocks may be held. | |
4954 | */ | |
36c8b586 | 4955 | int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask) |
1da177e4 | 4956 | { |
70b97a7f | 4957 | struct migration_req req; |
1da177e4 | 4958 | unsigned long flags; |
70b97a7f | 4959 | struct rq *rq; |
48f24c4d | 4960 | int ret = 0; |
1da177e4 LT |
4961 | |
4962 | rq = task_rq_lock(p, &flags); | |
4963 | if (!cpus_intersects(new_mask, cpu_online_map)) { | |
4964 | ret = -EINVAL; | |
4965 | goto out; | |
4966 | } | |
4967 | ||
4968 | p->cpus_allowed = new_mask; | |
4969 | /* Can the task run on the task's current CPU? If so, we're done */ | |
4970 | if (cpu_isset(task_cpu(p), new_mask)) | |
4971 | goto out; | |
4972 | ||
4973 | if (migrate_task(p, any_online_cpu(new_mask), &req)) { | |
4974 | /* Need help from migration thread: drop lock and wait. */ | |
4975 | task_rq_unlock(rq, &flags); | |
4976 | wake_up_process(rq->migration_thread); | |
4977 | wait_for_completion(&req.done); | |
4978 | tlb_migrate_finish(p->mm); | |
4979 | return 0; | |
4980 | } | |
4981 | out: | |
4982 | task_rq_unlock(rq, &flags); | |
48f24c4d | 4983 | |
1da177e4 LT |
4984 | return ret; |
4985 | } | |
1da177e4 LT |
4986 | EXPORT_SYMBOL_GPL(set_cpus_allowed); |
4987 | ||
4988 | /* | |
4989 | * Move (not current) task off this cpu, onto dest cpu. We're doing | |
4990 | * this because either it can't run here any more (set_cpus_allowed() | |
4991 | * away from this CPU, or CPU going down), or because we're | |
4992 | * attempting to rebalance this task on exec (sched_exec). | |
4993 | * | |
4994 | * So we race with normal scheduler movements, but that's OK, as long | |
4995 | * as the task is no longer on this CPU. | |
efc30814 KK |
4996 | * |
4997 | * Returns non-zero if task was successfully migrated. | |
1da177e4 | 4998 | */ |
efc30814 | 4999 | static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) |
1da177e4 | 5000 | { |
70b97a7f | 5001 | struct rq *rq_dest, *rq_src; |
efc30814 | 5002 | int ret = 0; |
1da177e4 LT |
5003 | |
5004 | if (unlikely(cpu_is_offline(dest_cpu))) | |
efc30814 | 5005 | return ret; |
1da177e4 LT |
5006 | |
5007 | rq_src = cpu_rq(src_cpu); | |
5008 | rq_dest = cpu_rq(dest_cpu); | |
5009 | ||
5010 | double_rq_lock(rq_src, rq_dest); | |
5011 | /* Already moved. */ | |
5012 | if (task_cpu(p) != src_cpu) | |
5013 | goto out; | |
5014 | /* Affinity changed (again). */ | |
5015 | if (!cpu_isset(dest_cpu, p->cpus_allowed)) | |
5016 | goto out; | |
5017 | ||
5018 | set_task_cpu(p, dest_cpu); | |
5019 | if (p->array) { | |
5020 | /* | |
5021 | * Sync timestamp with rq_dest's before activating. | |
5022 | * The same thing could be achieved by doing this step | |
5023 | * afterwards, and pretending it was a local activate. | |
5024 | * This way is cleaner and logically correct. | |
5025 | */ | |
5026 | p->timestamp = p->timestamp - rq_src->timestamp_last_tick | |
5027 | + rq_dest->timestamp_last_tick; | |
5028 | deactivate_task(p, rq_src); | |
0a565f79 | 5029 | __activate_task(p, rq_dest); |
1da177e4 LT |
5030 | if (TASK_PREEMPTS_CURR(p, rq_dest)) |
5031 | resched_task(rq_dest->curr); | |
5032 | } | |
efc30814 | 5033 | ret = 1; |
1da177e4 LT |
5034 | out: |
5035 | double_rq_unlock(rq_src, rq_dest); | |
efc30814 | 5036 | return ret; |
1da177e4 LT |
5037 | } |
5038 | ||
5039 | /* | |
5040 | * migration_thread - this is a highprio system thread that performs | |
5041 | * thread migration by bumping thread off CPU then 'pushing' onto | |
5042 | * another runqueue. | |
5043 | */ | |
95cdf3b7 | 5044 | static int migration_thread(void *data) |
1da177e4 | 5045 | { |
1da177e4 | 5046 | int cpu = (long)data; |
70b97a7f | 5047 | struct rq *rq; |
1da177e4 LT |
5048 | |
5049 | rq = cpu_rq(cpu); | |
5050 | BUG_ON(rq->migration_thread != current); | |
5051 | ||
5052 | set_current_state(TASK_INTERRUPTIBLE); | |
5053 | while (!kthread_should_stop()) { | |
70b97a7f | 5054 | struct migration_req *req; |
1da177e4 | 5055 | struct list_head *head; |
1da177e4 | 5056 | |
3e1d1d28 | 5057 | try_to_freeze(); |
1da177e4 LT |
5058 | |
5059 | spin_lock_irq(&rq->lock); | |
5060 | ||
5061 | if (cpu_is_offline(cpu)) { | |
5062 | spin_unlock_irq(&rq->lock); | |
5063 | goto wait_to_die; | |
5064 | } | |
5065 | ||
5066 | if (rq->active_balance) { | |
5067 | active_load_balance(rq, cpu); | |
5068 | rq->active_balance = 0; | |
5069 | } | |
5070 | ||
5071 | head = &rq->migration_queue; | |
5072 | ||
5073 | if (list_empty(head)) { | |
5074 | spin_unlock_irq(&rq->lock); | |
5075 | schedule(); | |
5076 | set_current_state(TASK_INTERRUPTIBLE); | |
5077 | continue; | |
5078 | } | |
70b97a7f | 5079 | req = list_entry(head->next, struct migration_req, list); |
1da177e4 LT |
5080 | list_del_init(head->next); |
5081 | ||
674311d5 NP |
5082 | spin_unlock(&rq->lock); |
5083 | __migrate_task(req->task, cpu, req->dest_cpu); | |
5084 | local_irq_enable(); | |
1da177e4 LT |
5085 | |
5086 | complete(&req->done); | |
5087 | } | |
5088 | __set_current_state(TASK_RUNNING); | |
5089 | return 0; | |
5090 | ||
5091 | wait_to_die: | |
5092 | /* Wait for kthread_stop */ | |
5093 | set_current_state(TASK_INTERRUPTIBLE); | |
5094 | while (!kthread_should_stop()) { | |
5095 | schedule(); | |
5096 | set_current_state(TASK_INTERRUPTIBLE); | |
5097 | } | |
5098 | __set_current_state(TASK_RUNNING); | |
5099 | return 0; | |
5100 | } | |
5101 | ||
5102 | #ifdef CONFIG_HOTPLUG_CPU | |
054b9108 KK |
5103 | /* |
5104 | * Figure out where task on dead CPU should go, use force if neccessary. | |
5105 | * NOTE: interrupts should be disabled by the caller | |
5106 | */ | |
48f24c4d | 5107 | static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p) |
1da177e4 | 5108 | { |
efc30814 | 5109 | unsigned long flags; |
1da177e4 | 5110 | cpumask_t mask; |
70b97a7f IM |
5111 | struct rq *rq; |
5112 | int dest_cpu; | |
1da177e4 | 5113 | |
efc30814 | 5114 | restart: |
1da177e4 LT |
5115 | /* On same node? */ |
5116 | mask = node_to_cpumask(cpu_to_node(dead_cpu)); | |
48f24c4d | 5117 | cpus_and(mask, mask, p->cpus_allowed); |
1da177e4 LT |
5118 | dest_cpu = any_online_cpu(mask); |
5119 | ||
5120 | /* On any allowed CPU? */ | |
5121 | if (dest_cpu == NR_CPUS) | |
48f24c4d | 5122 | dest_cpu = any_online_cpu(p->cpus_allowed); |
1da177e4 LT |
5123 | |
5124 | /* No more Mr. Nice Guy. */ | |
5125 | if (dest_cpu == NR_CPUS) { | |
48f24c4d IM |
5126 | rq = task_rq_lock(p, &flags); |
5127 | cpus_setall(p->cpus_allowed); | |
5128 | dest_cpu = any_online_cpu(p->cpus_allowed); | |
efc30814 | 5129 | task_rq_unlock(rq, &flags); |
1da177e4 LT |
5130 | |
5131 | /* | |
5132 | * Don't tell them about moving exiting tasks or | |
5133 | * kernel threads (both mm NULL), since they never | |
5134 | * leave kernel. | |
5135 | */ | |
48f24c4d | 5136 | if (p->mm && printk_ratelimit()) |
1da177e4 LT |
5137 | printk(KERN_INFO "process %d (%s) no " |
5138 | "longer affine to cpu%d\n", | |
48f24c4d | 5139 | p->pid, p->comm, dead_cpu); |
1da177e4 | 5140 | } |
48f24c4d | 5141 | if (!__migrate_task(p, dead_cpu, dest_cpu)) |
efc30814 | 5142 | goto restart; |
1da177e4 LT |
5143 | } |
5144 | ||
5145 | /* | |
5146 | * While a dead CPU has no uninterruptible tasks queued at this point, | |
5147 | * it might still have a nonzero ->nr_uninterruptible counter, because | |
5148 | * for performance reasons the counter is not stricly tracking tasks to | |
5149 | * their home CPUs. So we just add the counter to another CPU's counter, | |
5150 | * to keep the global sum constant after CPU-down: | |
5151 | */ | |
70b97a7f | 5152 | static void migrate_nr_uninterruptible(struct rq *rq_src) |
1da177e4 | 5153 | { |
70b97a7f | 5154 | struct rq *rq_dest = cpu_rq(any_online_cpu(CPU_MASK_ALL)); |
1da177e4 LT |
5155 | unsigned long flags; |
5156 | ||
5157 | local_irq_save(flags); | |
5158 | double_rq_lock(rq_src, rq_dest); | |
5159 | rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible; | |
5160 | rq_src->nr_uninterruptible = 0; | |
5161 | double_rq_unlock(rq_src, rq_dest); | |
5162 | local_irq_restore(flags); | |
5163 | } | |
5164 | ||
5165 | /* Run through task list and migrate tasks from the dead cpu. */ | |
5166 | static void migrate_live_tasks(int src_cpu) | |
5167 | { | |
48f24c4d | 5168 | struct task_struct *p, *t; |
1da177e4 LT |
5169 | |
5170 | write_lock_irq(&tasklist_lock); | |
5171 | ||
48f24c4d IM |
5172 | do_each_thread(t, p) { |
5173 | if (p == current) | |
1da177e4 LT |
5174 | continue; |
5175 | ||
48f24c4d IM |
5176 | if (task_cpu(p) == src_cpu) |
5177 | move_task_off_dead_cpu(src_cpu, p); | |
5178 | } while_each_thread(t, p); | |
1da177e4 LT |
5179 | |
5180 | write_unlock_irq(&tasklist_lock); | |
5181 | } | |
5182 | ||
5183 | /* Schedules idle task to be the next runnable task on current CPU. | |
5184 | * It does so by boosting its priority to highest possible and adding it to | |
48f24c4d | 5185 | * the _front_ of the runqueue. Used by CPU offline code. |
1da177e4 LT |
5186 | */ |
5187 | void sched_idle_next(void) | |
5188 | { | |
48f24c4d | 5189 | int this_cpu = smp_processor_id(); |
70b97a7f | 5190 | struct rq *rq = cpu_rq(this_cpu); |
1da177e4 LT |
5191 | struct task_struct *p = rq->idle; |
5192 | unsigned long flags; | |
5193 | ||
5194 | /* cpu has to be offline */ | |
48f24c4d | 5195 | BUG_ON(cpu_online(this_cpu)); |
1da177e4 | 5196 | |
48f24c4d IM |
5197 | /* |
5198 | * Strictly not necessary since rest of the CPUs are stopped by now | |
5199 | * and interrupts disabled on the current cpu. | |
1da177e4 LT |
5200 | */ |
5201 | spin_lock_irqsave(&rq->lock, flags); | |
5202 | ||
5203 | __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1); | |
48f24c4d IM |
5204 | |
5205 | /* Add idle task to the _front_ of its priority queue: */ | |
1da177e4 LT |
5206 | __activate_idle_task(p, rq); |
5207 | ||
5208 | spin_unlock_irqrestore(&rq->lock, flags); | |
5209 | } | |
5210 | ||
48f24c4d IM |
5211 | /* |
5212 | * Ensures that the idle task is using init_mm right before its cpu goes | |
1da177e4 LT |
5213 | * offline. |
5214 | */ | |
5215 | void idle_task_exit(void) | |
5216 | { | |
5217 | struct mm_struct *mm = current->active_mm; | |
5218 | ||
5219 | BUG_ON(cpu_online(smp_processor_id())); | |
5220 | ||
5221 | if (mm != &init_mm) | |
5222 | switch_mm(mm, &init_mm, current); | |
5223 | mmdrop(mm); | |
5224 | } | |
5225 | ||
054b9108 | 5226 | /* called under rq->lock with disabled interrupts */ |
36c8b586 | 5227 | static void migrate_dead(unsigned int dead_cpu, struct task_struct *p) |
1da177e4 | 5228 | { |
70b97a7f | 5229 | struct rq *rq = cpu_rq(dead_cpu); |
1da177e4 LT |
5230 | |
5231 | /* Must be exiting, otherwise would be on tasklist. */ | |
48f24c4d | 5232 | BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD); |
1da177e4 LT |
5233 | |
5234 | /* Cannot have done final schedule yet: would have vanished. */ | |
c394cc9f | 5235 | BUG_ON(p->state == TASK_DEAD); |
1da177e4 | 5236 | |
48f24c4d | 5237 | get_task_struct(p); |
1da177e4 LT |
5238 | |
5239 | /* | |
5240 | * Drop lock around migration; if someone else moves it, | |
5241 | * that's OK. No task can be added to this CPU, so iteration is | |
5242 | * fine. | |
054b9108 | 5243 | * NOTE: interrupts should be left disabled --dev@ |
1da177e4 | 5244 | */ |
054b9108 | 5245 | spin_unlock(&rq->lock); |
48f24c4d | 5246 | move_task_off_dead_cpu(dead_cpu, p); |
054b9108 | 5247 | spin_lock(&rq->lock); |
1da177e4 | 5248 | |
48f24c4d | 5249 | put_task_struct(p); |
1da177e4 LT |
5250 | } |
5251 | ||
5252 | /* release_task() removes task from tasklist, so we won't find dead tasks. */ | |
5253 | static void migrate_dead_tasks(unsigned int dead_cpu) | |
5254 | { | |
70b97a7f | 5255 | struct rq *rq = cpu_rq(dead_cpu); |
48f24c4d | 5256 | unsigned int arr, i; |
1da177e4 LT |
5257 | |
5258 | for (arr = 0; arr < 2; arr++) { | |
5259 | for (i = 0; i < MAX_PRIO; i++) { | |
5260 | struct list_head *list = &rq->arrays[arr].queue[i]; | |
48f24c4d | 5261 | |
1da177e4 | 5262 | while (!list_empty(list)) |
36c8b586 IM |
5263 | migrate_dead(dead_cpu, list_entry(list->next, |
5264 | struct task_struct, run_list)); | |
1da177e4 LT |
5265 | } |
5266 | } | |
5267 | } | |
5268 | #endif /* CONFIG_HOTPLUG_CPU */ | |
5269 | ||
5270 | /* | |
5271 | * migration_call - callback that gets triggered when a CPU is added. | |
5272 | * Here we can start up the necessary migration thread for the new CPU. | |
5273 | */ | |
48f24c4d IM |
5274 | static int __cpuinit |
5275 | migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) | |
1da177e4 | 5276 | { |
1da177e4 | 5277 | struct task_struct *p; |
48f24c4d | 5278 | int cpu = (long)hcpu; |
1da177e4 | 5279 | unsigned long flags; |
70b97a7f | 5280 | struct rq *rq; |
1da177e4 LT |
5281 | |
5282 | switch (action) { | |
5283 | case CPU_UP_PREPARE: | |
5284 | p = kthread_create(migration_thread, hcpu, "migration/%d",cpu); | |
5285 | if (IS_ERR(p)) | |
5286 | return NOTIFY_BAD; | |
5287 | p->flags |= PF_NOFREEZE; | |
5288 | kthread_bind(p, cpu); | |
5289 | /* Must be high prio: stop_machine expects to yield to it. */ | |
5290 | rq = task_rq_lock(p, &flags); | |
5291 | __setscheduler(p, SCHED_FIFO, MAX_RT_PRIO-1); | |
5292 | task_rq_unlock(rq, &flags); | |
5293 | cpu_rq(cpu)->migration_thread = p; | |
5294 | break; | |
48f24c4d | 5295 | |
1da177e4 LT |
5296 | case CPU_ONLINE: |
5297 | /* Strictly unneccessary, as first user will wake it. */ | |
5298 | wake_up_process(cpu_rq(cpu)->migration_thread); | |
5299 | break; | |
48f24c4d | 5300 | |
1da177e4 LT |
5301 | #ifdef CONFIG_HOTPLUG_CPU |
5302 | case CPU_UP_CANCELED: | |
fc75cdfa HC |
5303 | if (!cpu_rq(cpu)->migration_thread) |
5304 | break; | |
1da177e4 | 5305 | /* Unbind it from offline cpu so it can run. Fall thru. */ |
a4c4af7c HC |
5306 | kthread_bind(cpu_rq(cpu)->migration_thread, |
5307 | any_online_cpu(cpu_online_map)); | |
1da177e4 LT |
5308 | kthread_stop(cpu_rq(cpu)->migration_thread); |
5309 | cpu_rq(cpu)->migration_thread = NULL; | |
5310 | break; | |
48f24c4d | 5311 | |
1da177e4 LT |
5312 | case CPU_DEAD: |
5313 | migrate_live_tasks(cpu); | |
5314 | rq = cpu_rq(cpu); | |
5315 | kthread_stop(rq->migration_thread); | |
5316 | rq->migration_thread = NULL; | |
5317 | /* Idle task back to normal (off runqueue, low prio) */ | |
5318 | rq = task_rq_lock(rq->idle, &flags); | |
5319 | deactivate_task(rq->idle, rq); | |
5320 | rq->idle->static_prio = MAX_PRIO; | |
5321 | __setscheduler(rq->idle, SCHED_NORMAL, 0); | |
5322 | migrate_dead_tasks(cpu); | |
5323 | task_rq_unlock(rq, &flags); | |
5324 | migrate_nr_uninterruptible(rq); | |
5325 | BUG_ON(rq->nr_running != 0); | |
5326 | ||
5327 | /* No need to migrate the tasks: it was best-effort if | |
5328 | * they didn't do lock_cpu_hotplug(). Just wake up | |
5329 | * the requestors. */ | |
5330 | spin_lock_irq(&rq->lock); | |
5331 | while (!list_empty(&rq->migration_queue)) { | |
70b97a7f IM |
5332 | struct migration_req *req; |
5333 | ||
1da177e4 | 5334 | req = list_entry(rq->migration_queue.next, |
70b97a7f | 5335 | struct migration_req, list); |
1da177e4 LT |
5336 | list_del_init(&req->list); |
5337 | complete(&req->done); | |
5338 | } | |
5339 | spin_unlock_irq(&rq->lock); | |
5340 | break; | |
5341 | #endif | |
5342 | } | |
5343 | return NOTIFY_OK; | |
5344 | } | |
5345 | ||
5346 | /* Register at highest priority so that task migration (migrate_all_tasks) | |
5347 | * happens before everything else. | |
5348 | */ | |
26c2143b | 5349 | static struct notifier_block __cpuinitdata migration_notifier = { |
1da177e4 LT |
5350 | .notifier_call = migration_call, |
5351 | .priority = 10 | |
5352 | }; | |
5353 | ||
5354 | int __init migration_init(void) | |
5355 | { | |
5356 | void *cpu = (void *)(long)smp_processor_id(); | |
07dccf33 | 5357 | int err; |
48f24c4d IM |
5358 | |
5359 | /* Start one for the boot CPU: */ | |
07dccf33 AM |
5360 | err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); |
5361 | BUG_ON(err == NOTIFY_BAD); | |
1da177e4 LT |
5362 | migration_call(&migration_notifier, CPU_ONLINE, cpu); |
5363 | register_cpu_notifier(&migration_notifier); | |
48f24c4d | 5364 | |
1da177e4 LT |
5365 | return 0; |
5366 | } | |
5367 | #endif | |
5368 | ||
5369 | #ifdef CONFIG_SMP | |
1a20ff27 | 5370 | #undef SCHED_DOMAIN_DEBUG |
1da177e4 LT |
5371 | #ifdef SCHED_DOMAIN_DEBUG |
5372 | static void sched_domain_debug(struct sched_domain *sd, int cpu) | |
5373 | { | |
5374 | int level = 0; | |
5375 | ||
41c7ce9a NP |
5376 | if (!sd) { |
5377 | printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); | |
5378 | return; | |
5379 | } | |
5380 | ||
1da177e4 LT |
5381 | printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); |
5382 | ||
5383 | do { | |
5384 | int i; | |
5385 | char str[NR_CPUS]; | |
5386 | struct sched_group *group = sd->groups; | |
5387 | cpumask_t groupmask; | |
5388 | ||
5389 | cpumask_scnprintf(str, NR_CPUS, sd->span); | |
5390 | cpus_clear(groupmask); | |
5391 | ||
5392 | printk(KERN_DEBUG); | |
5393 | for (i = 0; i < level + 1; i++) | |
5394 | printk(" "); | |
5395 | printk("domain %d: ", level); | |
5396 | ||
5397 | if (!(sd->flags & SD_LOAD_BALANCE)) { | |
5398 | printk("does not load-balance\n"); | |
5399 | if (sd->parent) | |
5400 | printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent"); | |
5401 | break; | |
5402 | } | |
5403 | ||
5404 | printk("span %s\n", str); | |
5405 | ||
5406 | if (!cpu_isset(cpu, sd->span)) | |
5407 | printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu); | |
5408 | if (!cpu_isset(cpu, group->cpumask)) | |
5409 | printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu); | |
5410 | ||
5411 | printk(KERN_DEBUG); | |
5412 | for (i = 0; i < level + 2; i++) | |
5413 | printk(" "); | |
5414 | printk("groups:"); | |
5415 | do { | |
5416 | if (!group) { | |
5417 | printk("\n"); | |
5418 | printk(KERN_ERR "ERROR: group is NULL\n"); | |
5419 | break; | |
5420 | } | |
5421 | ||
5422 | if (!group->cpu_power) { | |
5423 | printk("\n"); | |
5424 | printk(KERN_ERR "ERROR: domain->cpu_power not set\n"); | |
5425 | } | |
5426 | ||
5427 | if (!cpus_weight(group->cpumask)) { | |
5428 | printk("\n"); | |
5429 | printk(KERN_ERR "ERROR: empty group\n"); | |
5430 | } | |
5431 | ||
5432 | if (cpus_intersects(groupmask, group->cpumask)) { | |
5433 | printk("\n"); | |
5434 | printk(KERN_ERR "ERROR: repeated CPUs\n"); | |
5435 | } | |
5436 | ||
5437 | cpus_or(groupmask, groupmask, group->cpumask); | |
5438 | ||
5439 | cpumask_scnprintf(str, NR_CPUS, group->cpumask); | |
5440 | printk(" %s", str); | |
5441 | ||
5442 | group = group->next; | |
5443 | } while (group != sd->groups); | |
5444 | printk("\n"); | |
5445 | ||
5446 | if (!cpus_equal(sd->span, groupmask)) | |
5447 | printk(KERN_ERR "ERROR: groups don't span domain->span\n"); | |
5448 | ||
5449 | level++; | |
5450 | sd = sd->parent; | |
5451 | ||
5452 | if (sd) { | |
5453 | if (!cpus_subset(groupmask, sd->span)) | |
5454 | printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n"); | |
5455 | } | |
5456 | ||
5457 | } while (sd); | |
5458 | } | |
5459 | #else | |
48f24c4d | 5460 | # define sched_domain_debug(sd, cpu) do { } while (0) |
1da177e4 LT |
5461 | #endif |
5462 | ||
1a20ff27 | 5463 | static int sd_degenerate(struct sched_domain *sd) |
245af2c7 SS |
5464 | { |
5465 | if (cpus_weight(sd->span) == 1) | |
5466 | return 1; | |
5467 | ||
5468 | /* Following flags need at least 2 groups */ | |
5469 | if (sd->flags & (SD_LOAD_BALANCE | | |
5470 | SD_BALANCE_NEWIDLE | | |
5471 | SD_BALANCE_FORK | | |
89c4710e SS |
5472 | SD_BALANCE_EXEC | |
5473 | SD_SHARE_CPUPOWER | | |
5474 | SD_SHARE_PKG_RESOURCES)) { | |
245af2c7 SS |
5475 | if (sd->groups != sd->groups->next) |
5476 | return 0; | |
5477 | } | |
5478 | ||
5479 | /* Following flags don't use groups */ | |
5480 | if (sd->flags & (SD_WAKE_IDLE | | |
5481 | SD_WAKE_AFFINE | | |
5482 | SD_WAKE_BALANCE)) | |
5483 | return 0; | |
5484 | ||
5485 | return 1; | |
5486 | } | |
5487 | ||
48f24c4d IM |
5488 | static int |
5489 | sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) | |
245af2c7 SS |
5490 | { |
5491 | unsigned long cflags = sd->flags, pflags = parent->flags; | |
5492 | ||
5493 | if (sd_degenerate(parent)) | |
5494 | return 1; | |
5495 | ||
5496 | if (!cpus_equal(sd->span, parent->span)) | |
5497 | return 0; | |
5498 | ||
5499 | /* Does parent contain flags not in child? */ | |
5500 | /* WAKE_BALANCE is a subset of WAKE_AFFINE */ | |
5501 | if (cflags & SD_WAKE_AFFINE) | |
5502 | pflags &= ~SD_WAKE_BALANCE; | |
5503 | /* Flags needing groups don't count if only 1 group in parent */ | |
5504 | if (parent->groups == parent->groups->next) { | |
5505 | pflags &= ~(SD_LOAD_BALANCE | | |
5506 | SD_BALANCE_NEWIDLE | | |
5507 | SD_BALANCE_FORK | | |
89c4710e SS |
5508 | SD_BALANCE_EXEC | |
5509 | SD_SHARE_CPUPOWER | | |
5510 | SD_SHARE_PKG_RESOURCES); | |
245af2c7 SS |
5511 | } |
5512 | if (~cflags & pflags) | |
5513 | return 0; | |
5514 | ||
5515 | return 1; | |
5516 | } | |
5517 | ||
1da177e4 LT |
5518 | /* |
5519 | * Attach the domain 'sd' to 'cpu' as its base domain. Callers must | |
5520 | * hold the hotplug lock. | |
5521 | */ | |
9c1cfda2 | 5522 | static void cpu_attach_domain(struct sched_domain *sd, int cpu) |
1da177e4 | 5523 | { |
70b97a7f | 5524 | struct rq *rq = cpu_rq(cpu); |
245af2c7 SS |
5525 | struct sched_domain *tmp; |
5526 | ||
5527 | /* Remove the sched domains which do not contribute to scheduling. */ | |
5528 | for (tmp = sd; tmp; tmp = tmp->parent) { | |
5529 | struct sched_domain *parent = tmp->parent; | |
5530 | if (!parent) | |
5531 | break; | |
1a848870 | 5532 | if (sd_parent_degenerate(tmp, parent)) { |
245af2c7 | 5533 | tmp->parent = parent->parent; |
1a848870 SS |
5534 | if (parent->parent) |
5535 | parent->parent->child = tmp; | |
5536 | } | |
245af2c7 SS |
5537 | } |
5538 | ||
1a848870 | 5539 | if (sd && sd_degenerate(sd)) { |
245af2c7 | 5540 | sd = sd->parent; |
1a848870 SS |
5541 | if (sd) |
5542 | sd->child = NULL; | |
5543 | } | |
1da177e4 LT |
5544 | |
5545 | sched_domain_debug(sd, cpu); | |
5546 | ||
674311d5 | 5547 | rcu_assign_pointer(rq->sd, sd); |
1da177e4 LT |
5548 | } |
5549 | ||
5550 | /* cpus with isolated domains */ | |
5c1e1767 | 5551 | static cpumask_t __cpuinitdata cpu_isolated_map = CPU_MASK_NONE; |
1da177e4 LT |
5552 | |
5553 | /* Setup the mask of cpus configured for isolated domains */ | |
5554 | static int __init isolated_cpu_setup(char *str) | |
5555 | { | |
5556 | int ints[NR_CPUS], i; | |
5557 | ||
5558 | str = get_options(str, ARRAY_SIZE(ints), ints); | |
5559 | cpus_clear(cpu_isolated_map); | |
5560 | for (i = 1; i <= ints[0]; i++) | |
5561 | if (ints[i] < NR_CPUS) | |
5562 | cpu_set(ints[i], cpu_isolated_map); | |
5563 | return 1; | |
5564 | } | |
5565 | ||
5566 | __setup ("isolcpus=", isolated_cpu_setup); | |
5567 | ||
5568 | /* | |
6711cab4 SS |
5569 | * init_sched_build_groups takes the cpumask we wish to span, and a pointer |
5570 | * to a function which identifies what group(along with sched group) a CPU | |
5571 | * belongs to. The return value of group_fn must be a >= 0 and < NR_CPUS | |
5572 | * (due to the fact that we keep track of groups covered with a cpumask_t). | |
1da177e4 LT |
5573 | * |
5574 | * init_sched_build_groups will build a circular linked list of the groups | |
5575 | * covered by the given span, and will set each group's ->cpumask correctly, | |
5576 | * and ->cpu_power to 0. | |
5577 | */ | |
a616058b | 5578 | static void |
6711cab4 SS |
5579 | init_sched_build_groups(cpumask_t span, const cpumask_t *cpu_map, |
5580 | int (*group_fn)(int cpu, const cpumask_t *cpu_map, | |
5581 | struct sched_group **sg)) | |
1da177e4 LT |
5582 | { |
5583 | struct sched_group *first = NULL, *last = NULL; | |
5584 | cpumask_t covered = CPU_MASK_NONE; | |
5585 | int i; | |
5586 | ||
5587 | for_each_cpu_mask(i, span) { | |
6711cab4 SS |
5588 | struct sched_group *sg; |
5589 | int group = group_fn(i, cpu_map, &sg); | |
1da177e4 LT |
5590 | int j; |
5591 | ||
5592 | if (cpu_isset(i, covered)) | |
5593 | continue; | |
5594 | ||
5595 | sg->cpumask = CPU_MASK_NONE; | |
5596 | sg->cpu_power = 0; | |
5597 | ||
5598 | for_each_cpu_mask(j, span) { | |
6711cab4 | 5599 | if (group_fn(j, cpu_map, NULL) != group) |
1da177e4 LT |
5600 | continue; |
5601 | ||
5602 | cpu_set(j, covered); | |
5603 | cpu_set(j, sg->cpumask); | |
5604 | } | |
5605 | if (!first) | |
5606 | first = sg; | |
5607 | if (last) | |
5608 | last->next = sg; | |
5609 | last = sg; | |
5610 | } | |
5611 | last->next = first; | |
5612 | } | |
5613 | ||
9c1cfda2 | 5614 | #define SD_NODES_PER_DOMAIN 16 |
1da177e4 | 5615 | |
198e2f18 | 5616 | /* |
5617 | * Self-tuning task migration cost measurement between source and target CPUs. | |
5618 | * | |
5619 | * This is done by measuring the cost of manipulating buffers of varying | |
5620 | * sizes. For a given buffer-size here are the steps that are taken: | |
5621 | * | |
5622 | * 1) the source CPU reads+dirties a shared buffer | |
5623 | * 2) the target CPU reads+dirties the same shared buffer | |
5624 | * | |
5625 | * We measure how long they take, in the following 4 scenarios: | |
5626 | * | |
5627 | * - source: CPU1, target: CPU2 | cost1 | |
5628 | * - source: CPU2, target: CPU1 | cost2 | |
5629 | * - source: CPU1, target: CPU1 | cost3 | |
5630 | * - source: CPU2, target: CPU2 | cost4 | |
5631 | * | |
5632 | * We then calculate the cost3+cost4-cost1-cost2 difference - this is | |
5633 | * the cost of migration. | |
5634 | * | |
5635 | * We then start off from a small buffer-size and iterate up to larger | |
5636 | * buffer sizes, in 5% steps - measuring each buffer-size separately, and | |
5637 | * doing a maximum search for the cost. (The maximum cost for a migration | |
5638 | * normally occurs when the working set size is around the effective cache | |
5639 | * size.) | |
5640 | */ | |
5641 | #define SEARCH_SCOPE 2 | |
5642 | #define MIN_CACHE_SIZE (64*1024U) | |
5643 | #define DEFAULT_CACHE_SIZE (5*1024*1024U) | |
70b4d63e | 5644 | #define ITERATIONS 1 |
198e2f18 | 5645 | #define SIZE_THRESH 130 |
5646 | #define COST_THRESH 130 | |
5647 | ||
5648 | /* | |
5649 | * The migration cost is a function of 'domain distance'. Domain | |
5650 | * distance is the number of steps a CPU has to iterate down its | |
5651 | * domain tree to share a domain with the other CPU. The farther | |
5652 | * two CPUs are from each other, the larger the distance gets. | |
5653 | * | |
5654 | * Note that we use the distance only to cache measurement results, | |
5655 | * the distance value is not used numerically otherwise. When two | |
5656 | * CPUs have the same distance it is assumed that the migration | |
5657 | * cost is the same. (this is a simplification but quite practical) | |
5658 | */ | |
5659 | #define MAX_DOMAIN_DISTANCE 32 | |
5660 | ||
5661 | static unsigned long long migration_cost[MAX_DOMAIN_DISTANCE] = | |
4bbf39c2 IM |
5662 | { [ 0 ... MAX_DOMAIN_DISTANCE-1 ] = |
5663 | /* | |
5664 | * Architectures may override the migration cost and thus avoid | |
5665 | * boot-time calibration. Unit is nanoseconds. Mostly useful for | |
5666 | * virtualized hardware: | |
5667 | */ | |
5668 | #ifdef CONFIG_DEFAULT_MIGRATION_COST | |
5669 | CONFIG_DEFAULT_MIGRATION_COST | |
5670 | #else | |
5671 | -1LL | |
5672 | #endif | |
5673 | }; | |
198e2f18 | 5674 | |
5675 | /* | |
5676 | * Allow override of migration cost - in units of microseconds. | |
5677 | * E.g. migration_cost=1000,2000,3000 will set up a level-1 cost | |
5678 | * of 1 msec, level-2 cost of 2 msecs and level3 cost of 3 msecs: | |
5679 | */ | |
5680 | static int __init migration_cost_setup(char *str) | |
5681 | { | |
5682 | int ints[MAX_DOMAIN_DISTANCE+1], i; | |
5683 | ||
5684 | str = get_options(str, ARRAY_SIZE(ints), ints); | |
5685 | ||
5686 | printk("#ints: %d\n", ints[0]); | |
5687 | for (i = 1; i <= ints[0]; i++) { | |
5688 | migration_cost[i-1] = (unsigned long long)ints[i]*1000; | |
5689 | printk("migration_cost[%d]: %Ld\n", i-1, migration_cost[i-1]); | |
5690 | } | |
5691 | return 1; | |
5692 | } | |
5693 | ||
5694 | __setup ("migration_cost=", migration_cost_setup); | |
5695 | ||
5696 | /* | |
5697 | * Global multiplier (divisor) for migration-cutoff values, | |
5698 | * in percentiles. E.g. use a value of 150 to get 1.5 times | |
5699 | * longer cache-hot cutoff times. | |
5700 | * | |
5701 | * (We scale it from 100 to 128 to long long handling easier.) | |
5702 | */ | |
5703 | ||
5704 | #define MIGRATION_FACTOR_SCALE 128 | |
5705 | ||
5706 | static unsigned int migration_factor = MIGRATION_FACTOR_SCALE; | |
5707 | ||
5708 | static int __init setup_migration_factor(char *str) | |
5709 | { | |
5710 | get_option(&str, &migration_factor); | |
5711 | migration_factor = migration_factor * MIGRATION_FACTOR_SCALE / 100; | |
5712 | return 1; | |
5713 | } | |
5714 | ||
5715 | __setup("migration_factor=", setup_migration_factor); | |
5716 | ||
5717 | /* | |
5718 | * Estimated distance of two CPUs, measured via the number of domains | |
5719 | * we have to pass for the two CPUs to be in the same span: | |
5720 | */ | |
5721 | static unsigned long domain_distance(int cpu1, int cpu2) | |
5722 | { | |
5723 | unsigned long distance = 0; | |
5724 | struct sched_domain *sd; | |
5725 | ||
5726 | for_each_domain(cpu1, sd) { | |
5727 | WARN_ON(!cpu_isset(cpu1, sd->span)); | |
5728 | if (cpu_isset(cpu2, sd->span)) | |
5729 | return distance; | |
5730 | distance++; | |
5731 | } | |
5732 | if (distance >= MAX_DOMAIN_DISTANCE) { | |
5733 | WARN_ON(1); | |
5734 | distance = MAX_DOMAIN_DISTANCE-1; | |
5735 | } | |
5736 | ||
5737 | return distance; | |
5738 | } | |
5739 | ||
5740 | static unsigned int migration_debug; | |
5741 | ||
5742 | static int __init setup_migration_debug(char *str) | |
5743 | { | |
5744 | get_option(&str, &migration_debug); | |
5745 | return 1; | |
5746 | } | |
5747 | ||
5748 | __setup("migration_debug=", setup_migration_debug); | |
5749 | ||
5750 | /* | |
5751 | * Maximum cache-size that the scheduler should try to measure. | |
5752 | * Architectures with larger caches should tune this up during | |
5753 | * bootup. Gets used in the domain-setup code (i.e. during SMP | |
5754 | * bootup). | |
5755 | */ | |
5756 | unsigned int max_cache_size; | |
5757 | ||
5758 | static int __init setup_max_cache_size(char *str) | |
5759 | { | |
5760 | get_option(&str, &max_cache_size); | |
5761 | return 1; | |
5762 | } | |
5763 | ||
5764 | __setup("max_cache_size=", setup_max_cache_size); | |
5765 | ||
5766 | /* | |
5767 | * Dirty a big buffer in a hard-to-predict (for the L2 cache) way. This | |
5768 | * is the operation that is timed, so we try to generate unpredictable | |
5769 | * cachemisses that still end up filling the L2 cache: | |
5770 | */ | |
5771 | static void touch_cache(void *__cache, unsigned long __size) | |
5772 | { | |
5773 | unsigned long size = __size/sizeof(long), chunk1 = size/3, | |
5774 | chunk2 = 2*size/3; | |
5775 | unsigned long *cache = __cache; | |
5776 | int i; | |
5777 | ||
5778 | for (i = 0; i < size/6; i += 8) { | |
5779 | switch (i % 6) { | |
5780 | case 0: cache[i]++; | |
5781 | case 1: cache[size-1-i]++; | |
5782 | case 2: cache[chunk1-i]++; | |
5783 | case 3: cache[chunk1+i]++; | |
5784 | case 4: cache[chunk2-i]++; | |
5785 | case 5: cache[chunk2+i]++; | |
5786 | } | |
5787 | } | |
5788 | } | |
5789 | ||
5790 | /* | |
5791 | * Measure the cache-cost of one task migration. Returns in units of nsec. | |
5792 | */ | |
48f24c4d IM |
5793 | static unsigned long long |
5794 | measure_one(void *cache, unsigned long size, int source, int target) | |
198e2f18 | 5795 | { |
5796 | cpumask_t mask, saved_mask; | |
5797 | unsigned long long t0, t1, t2, t3, cost; | |
5798 | ||
5799 | saved_mask = current->cpus_allowed; | |
5800 | ||
5801 | /* | |
5802 | * Flush source caches to RAM and invalidate them: | |
5803 | */ | |
5804 | sched_cacheflush(); | |
5805 | ||
5806 | /* | |
5807 | * Migrate to the source CPU: | |
5808 | */ | |
5809 | mask = cpumask_of_cpu(source); | |
5810 | set_cpus_allowed(current, mask); | |
5811 | WARN_ON(smp_processor_id() != source); | |
5812 | ||
5813 | /* | |
5814 | * Dirty the working set: | |
5815 | */ | |
5816 | t0 = sched_clock(); | |
5817 | touch_cache(cache, size); | |
5818 | t1 = sched_clock(); | |
5819 | ||
5820 | /* | |
5821 | * Migrate to the target CPU, dirty the L2 cache and access | |
5822 | * the shared buffer. (which represents the working set | |
5823 | * of a migrated task.) | |
5824 | */ | |
5825 | mask = cpumask_of_cpu(target); | |
5826 | set_cpus_allowed(current, mask); | |
5827 | WARN_ON(smp_processor_id() != target); | |
5828 | ||
5829 | t2 = sched_clock(); | |
5830 | touch_cache(cache, size); | |
5831 | t3 = sched_clock(); | |
5832 | ||
5833 | cost = t1-t0 + t3-t2; | |
5834 | ||
5835 | if (migration_debug >= 2) | |
5836 | printk("[%d->%d]: %8Ld %8Ld %8Ld => %10Ld.\n", | |
5837 | source, target, t1-t0, t1-t0, t3-t2, cost); | |
5838 | /* | |
5839 | * Flush target caches to RAM and invalidate them: | |
5840 | */ | |
5841 | sched_cacheflush(); | |
5842 | ||
5843 | set_cpus_allowed(current, saved_mask); | |
5844 | ||
5845 | return cost; | |
5846 | } | |
5847 | ||
5848 | /* | |
5849 | * Measure a series of task migrations and return the average | |
5850 | * result. Since this code runs early during bootup the system | |
5851 | * is 'undisturbed' and the average latency makes sense. | |
5852 | * | |
5853 | * The algorithm in essence auto-detects the relevant cache-size, | |
5854 | * so it will properly detect different cachesizes for different | |
5855 | * cache-hierarchies, depending on how the CPUs are connected. | |
5856 | * | |
5857 | * Architectures can prime the upper limit of the search range via | |
5858 | * max_cache_size, otherwise the search range defaults to 20MB...64K. | |
5859 | */ | |
5860 | static unsigned long long | |
5861 | measure_cost(int cpu1, int cpu2, void *cache, unsigned int size) | |
5862 | { | |
5863 | unsigned long long cost1, cost2; | |
5864 | int i; | |
5865 | ||
5866 | /* | |
5867 | * Measure the migration cost of 'size' bytes, over an | |
5868 | * average of 10 runs: | |
5869 | * | |
5870 | * (We perturb the cache size by a small (0..4k) | |
5871 | * value to compensate size/alignment related artifacts. | |
5872 | * We also subtract the cost of the operation done on | |
5873 | * the same CPU.) | |
5874 | */ | |
5875 | cost1 = 0; | |
5876 | ||
5877 | /* | |
5878 | * dry run, to make sure we start off cache-cold on cpu1, | |
5879 | * and to get any vmalloc pagefaults in advance: | |
5880 | */ | |
5881 | measure_one(cache, size, cpu1, cpu2); | |
5882 | for (i = 0; i < ITERATIONS; i++) | |
5883 | cost1 += measure_one(cache, size - i*1024, cpu1, cpu2); | |
5884 | ||
5885 | measure_one(cache, size, cpu2, cpu1); | |
5886 | for (i = 0; i < ITERATIONS; i++) | |
5887 | cost1 += measure_one(cache, size - i*1024, cpu2, cpu1); | |
5888 | ||
5889 | /* | |
5890 | * (We measure the non-migrating [cached] cost on both | |
5891 | * cpu1 and cpu2, to handle CPUs with different speeds) | |
5892 | */ | |
5893 | cost2 = 0; | |
5894 | ||
5895 | measure_one(cache, size, cpu1, cpu1); | |
5896 | for (i = 0; i < ITERATIONS; i++) | |
5897 | cost2 += measure_one(cache, size - i*1024, cpu1, cpu1); | |
5898 | ||
5899 | measure_one(cache, size, cpu2, cpu2); | |
5900 | for (i = 0; i < ITERATIONS; i++) | |
5901 | cost2 += measure_one(cache, size - i*1024, cpu2, cpu2); | |
5902 | ||
5903 | /* | |
5904 | * Get the per-iteration migration cost: | |
5905 | */ | |
5906 | do_div(cost1, 2*ITERATIONS); | |
5907 | do_div(cost2, 2*ITERATIONS); | |
5908 | ||
5909 | return cost1 - cost2; | |
5910 | } | |
5911 | ||
5912 | static unsigned long long measure_migration_cost(int cpu1, int cpu2) | |
5913 | { | |
5914 | unsigned long long max_cost = 0, fluct = 0, avg_fluct = 0; | |
5915 | unsigned int max_size, size, size_found = 0; | |
5916 | long long cost = 0, prev_cost; | |
5917 | void *cache; | |
5918 | ||
5919 | /* | |
5920 | * Search from max_cache_size*5 down to 64K - the real relevant | |
5921 | * cachesize has to lie somewhere inbetween. | |
5922 | */ | |
5923 | if (max_cache_size) { | |
5924 | max_size = max(max_cache_size * SEARCH_SCOPE, MIN_CACHE_SIZE); | |
5925 | size = max(max_cache_size / SEARCH_SCOPE, MIN_CACHE_SIZE); | |
5926 | } else { | |
5927 | /* | |
5928 | * Since we have no estimation about the relevant | |
5929 | * search range | |
5930 | */ | |
5931 | max_size = DEFAULT_CACHE_SIZE * SEARCH_SCOPE; | |
5932 | size = MIN_CACHE_SIZE; | |
5933 | } | |
5934 | ||
5935 | if (!cpu_online(cpu1) || !cpu_online(cpu2)) { | |
5936 | printk("cpu %d and %d not both online!\n", cpu1, cpu2); | |
5937 | return 0; | |
5938 | } | |
5939 | ||
5940 | /* | |
5941 | * Allocate the working set: | |
5942 | */ | |
5943 | cache = vmalloc(max_size); | |
5944 | if (!cache) { | |
5945 | printk("could not vmalloc %d bytes for cache!\n", 2*max_size); | |
2ed6e34f | 5946 | return 1000000; /* return 1 msec on very small boxen */ |
198e2f18 | 5947 | } |
5948 | ||
5949 | while (size <= max_size) { | |
5950 | prev_cost = cost; | |
5951 | cost = measure_cost(cpu1, cpu2, cache, size); | |
5952 | ||
5953 | /* | |
5954 | * Update the max: | |
5955 | */ | |
5956 | if (cost > 0) { | |
5957 | if (max_cost < cost) { | |
5958 | max_cost = cost; | |
5959 | size_found = size; | |
5960 | } | |
5961 | } | |
5962 | /* | |
5963 | * Calculate average fluctuation, we use this to prevent | |
5964 | * noise from triggering an early break out of the loop: | |
5965 | */ | |
5966 | fluct = abs(cost - prev_cost); | |
5967 | avg_fluct = (avg_fluct + fluct)/2; | |
5968 | ||
5969 | if (migration_debug) | |
5970 | printk("-> [%d][%d][%7d] %3ld.%ld [%3ld.%ld] (%ld): (%8Ld %8Ld)\n", | |
5971 | cpu1, cpu2, size, | |
5972 | (long)cost / 1000000, | |
5973 | ((long)cost / 100000) % 10, | |
5974 | (long)max_cost / 1000000, | |
5975 | ((long)max_cost / 100000) % 10, | |
5976 | domain_distance(cpu1, cpu2), | |
5977 | cost, avg_fluct); | |
5978 | ||
5979 | /* | |
5980 | * If we iterated at least 20% past the previous maximum, | |
5981 | * and the cost has dropped by more than 20% already, | |
5982 | * (taking fluctuations into account) then we assume to | |
5983 | * have found the maximum and break out of the loop early: | |
5984 | */ | |
5985 | if (size_found && (size*100 > size_found*SIZE_THRESH)) | |
5986 | if (cost+avg_fluct <= 0 || | |
5987 | max_cost*100 > (cost+avg_fluct)*COST_THRESH) { | |
5988 | ||
5989 | if (migration_debug) | |
5990 | printk("-> found max.\n"); | |
5991 | break; | |
5992 | } | |
5993 | /* | |
70b4d63e | 5994 | * Increase the cachesize in 10% steps: |
198e2f18 | 5995 | */ |
70b4d63e | 5996 | size = size * 10 / 9; |
198e2f18 | 5997 | } |
5998 | ||
5999 | if (migration_debug) | |
6000 | printk("[%d][%d] working set size found: %d, cost: %Ld\n", | |
6001 | cpu1, cpu2, size_found, max_cost); | |
6002 | ||
6003 | vfree(cache); | |
6004 | ||
6005 | /* | |
6006 | * A task is considered 'cache cold' if at least 2 times | |
6007 | * the worst-case cost of migration has passed. | |
6008 | * | |
6009 | * (this limit is only listened to if the load-balancing | |
6010 | * situation is 'nice' - if there is a large imbalance we | |
6011 | * ignore it for the sake of CPU utilization and | |
6012 | * processing fairness.) | |
6013 | */ | |
6014 | return 2 * max_cost * migration_factor / MIGRATION_FACTOR_SCALE; | |
6015 | } | |
6016 | ||
6017 | static void calibrate_migration_costs(const cpumask_t *cpu_map) | |
6018 | { | |
6019 | int cpu1 = -1, cpu2 = -1, cpu, orig_cpu = raw_smp_processor_id(); | |
6020 | unsigned long j0, j1, distance, max_distance = 0; | |
6021 | struct sched_domain *sd; | |
6022 | ||
6023 | j0 = jiffies; | |
6024 | ||
6025 | /* | |
6026 | * First pass - calculate the cacheflush times: | |
6027 | */ | |
6028 | for_each_cpu_mask(cpu1, *cpu_map) { | |
6029 | for_each_cpu_mask(cpu2, *cpu_map) { | |
6030 | if (cpu1 == cpu2) | |
6031 | continue; | |
6032 | distance = domain_distance(cpu1, cpu2); | |
6033 | max_distance = max(max_distance, distance); | |
6034 | /* | |
6035 | * No result cached yet? | |
6036 | */ | |
6037 | if (migration_cost[distance] == -1LL) | |
6038 | migration_cost[distance] = | |
6039 | measure_migration_cost(cpu1, cpu2); | |
6040 | } | |
6041 | } | |
6042 | /* | |
6043 | * Second pass - update the sched domain hierarchy with | |
6044 | * the new cache-hot-time estimations: | |
6045 | */ | |
6046 | for_each_cpu_mask(cpu, *cpu_map) { | |
6047 | distance = 0; | |
6048 | for_each_domain(cpu, sd) { | |
6049 | sd->cache_hot_time = migration_cost[distance]; | |
6050 | distance++; | |
6051 | } | |
6052 | } | |
6053 | /* | |
6054 | * Print the matrix: | |
6055 | */ | |
6056 | if (migration_debug) | |
6057 | printk("migration: max_cache_size: %d, cpu: %d MHz:\n", | |
6058 | max_cache_size, | |
6059 | #ifdef CONFIG_X86 | |
6060 | cpu_khz/1000 | |
6061 | #else | |
6062 | -1 | |
6063 | #endif | |
6064 | ); | |
bd576c95 | 6065 | if (system_state == SYSTEM_BOOTING) { |
74732646 DJ |
6066 | if (num_online_cpus() > 1) { |
6067 | printk("migration_cost="); | |
6068 | for (distance = 0; distance <= max_distance; distance++) { | |
6069 | if (distance) | |
6070 | printk(","); | |
6071 | printk("%ld", (long)migration_cost[distance] / 1000); | |
6072 | } | |
6073 | printk("\n"); | |
bd576c95 | 6074 | } |
198e2f18 | 6075 | } |
198e2f18 | 6076 | j1 = jiffies; |
6077 | if (migration_debug) | |
6078 | printk("migration: %ld seconds\n", (j1-j0)/HZ); | |
6079 | ||
6080 | /* | |
6081 | * Move back to the original CPU. NUMA-Q gets confused | |
6082 | * if we migrate to another quad during bootup. | |
6083 | */ | |
6084 | if (raw_smp_processor_id() != orig_cpu) { | |
6085 | cpumask_t mask = cpumask_of_cpu(orig_cpu), | |
6086 | saved_mask = current->cpus_allowed; | |
6087 | ||
6088 | set_cpus_allowed(current, mask); | |
6089 | set_cpus_allowed(current, saved_mask); | |
6090 | } | |
6091 | } | |
6092 | ||
9c1cfda2 | 6093 | #ifdef CONFIG_NUMA |
198e2f18 | 6094 | |
9c1cfda2 JH |
6095 | /** |
6096 | * find_next_best_node - find the next node to include in a sched_domain | |
6097 | * @node: node whose sched_domain we're building | |
6098 | * @used_nodes: nodes already in the sched_domain | |
6099 | * | |
6100 | * Find the next node to include in a given scheduling domain. Simply | |
6101 | * finds the closest node not already in the @used_nodes map. | |
6102 | * | |
6103 | * Should use nodemask_t. | |
6104 | */ | |
6105 | static int find_next_best_node(int node, unsigned long *used_nodes) | |
6106 | { | |
6107 | int i, n, val, min_val, best_node = 0; | |
6108 | ||
6109 | min_val = INT_MAX; | |
6110 | ||
6111 | for (i = 0; i < MAX_NUMNODES; i++) { | |
6112 | /* Start at @node */ | |
6113 | n = (node + i) % MAX_NUMNODES; | |
6114 | ||
6115 | if (!nr_cpus_node(n)) | |
6116 | continue; | |
6117 | ||
6118 | /* Skip already used nodes */ | |
6119 | if (test_bit(n, used_nodes)) | |
6120 | continue; | |
6121 | ||
6122 | /* Simple min distance search */ | |
6123 | val = node_distance(node, n); | |
6124 | ||
6125 | if (val < min_val) { | |
6126 | min_val = val; | |
6127 | best_node = n; | |
6128 | } | |
6129 | } | |
6130 | ||
6131 | set_bit(best_node, used_nodes); | |
6132 | return best_node; | |
6133 | } | |
6134 | ||
6135 | /** | |
6136 | * sched_domain_node_span - get a cpumask for a node's sched_domain | |
6137 | * @node: node whose cpumask we're constructing | |
6138 | * @size: number of nodes to include in this span | |
6139 | * | |
6140 | * Given a node, construct a good cpumask for its sched_domain to span. It | |
6141 | * should be one that prevents unnecessary balancing, but also spreads tasks | |
6142 | * out optimally. | |
6143 | */ | |
6144 | static cpumask_t sched_domain_node_span(int node) | |
6145 | { | |
9c1cfda2 | 6146 | DECLARE_BITMAP(used_nodes, MAX_NUMNODES); |
48f24c4d IM |
6147 | cpumask_t span, nodemask; |
6148 | int i; | |
9c1cfda2 JH |
6149 | |
6150 | cpus_clear(span); | |
6151 | bitmap_zero(used_nodes, MAX_NUMNODES); | |
6152 | ||
6153 | nodemask = node_to_cpumask(node); | |
6154 | cpus_or(span, span, nodemask); | |
6155 | set_bit(node, used_nodes); | |
6156 | ||
6157 | for (i = 1; i < SD_NODES_PER_DOMAIN; i++) { | |
6158 | int next_node = find_next_best_node(node, used_nodes); | |
48f24c4d | 6159 | |
9c1cfda2 JH |
6160 | nodemask = node_to_cpumask(next_node); |
6161 | cpus_or(span, span, nodemask); | |
6162 | } | |
6163 | ||
6164 | return span; | |
6165 | } | |
6166 | #endif | |
6167 | ||
5c45bf27 | 6168 | int sched_smt_power_savings = 0, sched_mc_power_savings = 0; |
48f24c4d | 6169 | |
9c1cfda2 | 6170 | /* |
48f24c4d | 6171 | * SMT sched-domains: |
9c1cfda2 | 6172 | */ |
1da177e4 LT |
6173 | #ifdef CONFIG_SCHED_SMT |
6174 | static DEFINE_PER_CPU(struct sched_domain, cpu_domains); | |
6711cab4 | 6175 | static DEFINE_PER_CPU(struct sched_group, sched_group_cpus); |
48f24c4d | 6176 | |
6711cab4 SS |
6177 | static int cpu_to_cpu_group(int cpu, const cpumask_t *cpu_map, |
6178 | struct sched_group **sg) | |
1da177e4 | 6179 | { |
6711cab4 SS |
6180 | if (sg) |
6181 | *sg = &per_cpu(sched_group_cpus, cpu); | |
1da177e4 LT |
6182 | return cpu; |
6183 | } | |
6184 | #endif | |
6185 | ||
48f24c4d IM |
6186 | /* |
6187 | * multi-core sched-domains: | |
6188 | */ | |
1e9f28fa SS |
6189 | #ifdef CONFIG_SCHED_MC |
6190 | static DEFINE_PER_CPU(struct sched_domain, core_domains); | |
6711cab4 | 6191 | static DEFINE_PER_CPU(struct sched_group, sched_group_core); |
1e9f28fa SS |
6192 | #endif |
6193 | ||
6194 | #if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_SMT) | |
6711cab4 SS |
6195 | static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map, |
6196 | struct sched_group **sg) | |
1e9f28fa | 6197 | { |
6711cab4 | 6198 | int group; |
a616058b SS |
6199 | cpumask_t mask = cpu_sibling_map[cpu]; |
6200 | cpus_and(mask, mask, *cpu_map); | |
6711cab4 SS |
6201 | group = first_cpu(mask); |
6202 | if (sg) | |
6203 | *sg = &per_cpu(sched_group_core, group); | |
6204 | return group; | |
1e9f28fa SS |
6205 | } |
6206 | #elif defined(CONFIG_SCHED_MC) | |
6711cab4 SS |
6207 | static int cpu_to_core_group(int cpu, const cpumask_t *cpu_map, |
6208 | struct sched_group **sg) | |
1e9f28fa | 6209 | { |
6711cab4 SS |
6210 | if (sg) |
6211 | *sg = &per_cpu(sched_group_core, cpu); | |
1e9f28fa SS |
6212 | return cpu; |
6213 | } | |
6214 | #endif | |
6215 | ||
1da177e4 | 6216 | static DEFINE_PER_CPU(struct sched_domain, phys_domains); |
6711cab4 | 6217 | static DEFINE_PER_CPU(struct sched_group, sched_group_phys); |
48f24c4d | 6218 | |
6711cab4 SS |
6219 | static int cpu_to_phys_group(int cpu, const cpumask_t *cpu_map, |
6220 | struct sched_group **sg) | |
1da177e4 | 6221 | { |
6711cab4 | 6222 | int group; |
48f24c4d | 6223 | #ifdef CONFIG_SCHED_MC |
1e9f28fa | 6224 | cpumask_t mask = cpu_coregroup_map(cpu); |
a616058b | 6225 | cpus_and(mask, mask, *cpu_map); |
6711cab4 | 6226 | group = first_cpu(mask); |
1e9f28fa | 6227 | #elif defined(CONFIG_SCHED_SMT) |
a616058b SS |
6228 | cpumask_t mask = cpu_sibling_map[cpu]; |
6229 | cpus_and(mask, mask, *cpu_map); | |
6711cab4 | 6230 | group = first_cpu(mask); |
1da177e4 | 6231 | #else |
6711cab4 | 6232 | group = cpu; |
1da177e4 | 6233 | #endif |
6711cab4 SS |
6234 | if (sg) |
6235 | *sg = &per_cpu(sched_group_phys, group); | |
6236 | return group; | |
1da177e4 LT |
6237 | } |
6238 | ||
6239 | #ifdef CONFIG_NUMA | |
1da177e4 | 6240 | /* |
9c1cfda2 JH |
6241 | * The init_sched_build_groups can't handle what we want to do with node |
6242 | * groups, so roll our own. Now each node has its own list of groups which | |
6243 | * gets dynamically allocated. | |
1da177e4 | 6244 | */ |
9c1cfda2 | 6245 | static DEFINE_PER_CPU(struct sched_domain, node_domains); |
d1b55138 | 6246 | static struct sched_group **sched_group_nodes_bycpu[NR_CPUS]; |
1da177e4 | 6247 | |
9c1cfda2 | 6248 | static DEFINE_PER_CPU(struct sched_domain, allnodes_domains); |
6711cab4 | 6249 | static DEFINE_PER_CPU(struct sched_group, sched_group_allnodes); |
9c1cfda2 | 6250 | |
6711cab4 SS |
6251 | static int cpu_to_allnodes_group(int cpu, const cpumask_t *cpu_map, |
6252 | struct sched_group **sg) | |
9c1cfda2 | 6253 | { |
6711cab4 SS |
6254 | cpumask_t nodemask = node_to_cpumask(cpu_to_node(cpu)); |
6255 | int group; | |
6256 | ||
6257 | cpus_and(nodemask, nodemask, *cpu_map); | |
6258 | group = first_cpu(nodemask); | |
6259 | ||
6260 | if (sg) | |
6261 | *sg = &per_cpu(sched_group_allnodes, group); | |
6262 | return group; | |
1da177e4 | 6263 | } |
6711cab4 | 6264 | |
08069033 SS |
6265 | static void init_numa_sched_groups_power(struct sched_group *group_head) |
6266 | { | |
6267 | struct sched_group *sg = group_head; | |
6268 | int j; | |
6269 | ||
6270 | if (!sg) | |
6271 | return; | |
6272 | next_sg: | |
6273 | for_each_cpu_mask(j, sg->cpumask) { | |
6274 | struct sched_domain *sd; | |
6275 | ||
6276 | sd = &per_cpu(phys_domains, j); | |
6277 | if (j != first_cpu(sd->groups->cpumask)) { | |
6278 | /* | |
6279 | * Only add "power" once for each | |
6280 | * physical package. | |
6281 | */ | |
6282 | continue; | |
6283 | } | |
6284 | ||
6285 | sg->cpu_power += sd->groups->cpu_power; | |
6286 | } | |
6287 | sg = sg->next; | |
6288 | if (sg != group_head) | |
6289 | goto next_sg; | |
6290 | } | |
1da177e4 LT |
6291 | #endif |
6292 | ||
a616058b | 6293 | #ifdef CONFIG_NUMA |
51888ca2 SV |
6294 | /* Free memory allocated for various sched_group structures */ |
6295 | static void free_sched_groups(const cpumask_t *cpu_map) | |
6296 | { | |
a616058b | 6297 | int cpu, i; |
51888ca2 SV |
6298 | |
6299 | for_each_cpu_mask(cpu, *cpu_map) { | |
51888ca2 SV |
6300 | struct sched_group **sched_group_nodes |
6301 | = sched_group_nodes_bycpu[cpu]; | |
6302 | ||
51888ca2 SV |
6303 | if (!sched_group_nodes) |
6304 | continue; | |
6305 | ||
6306 | for (i = 0; i < MAX_NUMNODES; i++) { | |
6307 | cpumask_t nodemask = node_to_cpumask(i); | |
6308 | struct sched_group *oldsg, *sg = sched_group_nodes[i]; | |
6309 | ||
6310 | cpus_and(nodemask, nodemask, *cpu_map); | |
6311 | if (cpus_empty(nodemask)) | |
6312 | continue; | |
6313 | ||
6314 | if (sg == NULL) | |
6315 | continue; | |
6316 | sg = sg->next; | |
6317 | next_sg: | |
6318 | oldsg = sg; | |
6319 | sg = sg->next; | |
6320 | kfree(oldsg); | |
6321 | if (oldsg != sched_group_nodes[i]) | |
6322 | goto next_sg; | |
6323 | } | |
6324 | kfree(sched_group_nodes); | |
6325 | sched_group_nodes_bycpu[cpu] = NULL; | |
6326 | } | |
51888ca2 | 6327 | } |
a616058b SS |
6328 | #else |
6329 | static void free_sched_groups(const cpumask_t *cpu_map) | |
6330 | { | |
6331 | } | |
6332 | #endif | |
51888ca2 | 6333 | |
89c4710e SS |
6334 | /* |
6335 | * Initialize sched groups cpu_power. | |
6336 | * | |
6337 | * cpu_power indicates the capacity of sched group, which is used while | |
6338 | * distributing the load between different sched groups in a sched domain. | |
6339 | * Typically cpu_power for all the groups in a sched domain will be same unless | |
6340 | * there are asymmetries in the topology. If there are asymmetries, group | |
6341 | * having more cpu_power will pickup more load compared to the group having | |
6342 | * less cpu_power. | |
6343 | * | |
6344 | * cpu_power will be a multiple of SCHED_LOAD_SCALE. This multiple represents | |
6345 | * the maximum number of tasks a group can handle in the presence of other idle | |
6346 | * or lightly loaded groups in the same sched domain. | |
6347 | */ | |
6348 | static void init_sched_groups_power(int cpu, struct sched_domain *sd) | |
6349 | { | |
6350 | struct sched_domain *child; | |
6351 | struct sched_group *group; | |
6352 | ||
6353 | WARN_ON(!sd || !sd->groups); | |
6354 | ||
6355 | if (cpu != first_cpu(sd->groups->cpumask)) | |
6356 | return; | |
6357 | ||
6358 | child = sd->child; | |
6359 | ||
6360 | /* | |
6361 | * For perf policy, if the groups in child domain share resources | |
6362 | * (for example cores sharing some portions of the cache hierarchy | |
6363 | * or SMT), then set this domain groups cpu_power such that each group | |
6364 | * can handle only one task, when there are other idle groups in the | |
6365 | * same sched domain. | |
6366 | */ | |
6367 | if (!child || (!(sd->flags & SD_POWERSAVINGS_BALANCE) && | |
6368 | (child->flags & | |
6369 | (SD_SHARE_CPUPOWER | SD_SHARE_PKG_RESOURCES)))) { | |
6370 | sd->groups->cpu_power = SCHED_LOAD_SCALE; | |
6371 | return; | |
6372 | } | |
6373 | ||
6374 | sd->groups->cpu_power = 0; | |
6375 | ||
6376 | /* | |
6377 | * add cpu_power of each child group to this groups cpu_power | |
6378 | */ | |
6379 | group = child->groups; | |
6380 | do { | |
6381 | sd->groups->cpu_power += group->cpu_power; | |
6382 | group = group->next; | |
6383 | } while (group != child->groups); | |
6384 | } | |
6385 | ||
1da177e4 | 6386 | /* |
1a20ff27 DG |
6387 | * Build sched domains for a given set of cpus and attach the sched domains |
6388 | * to the individual cpus | |
1da177e4 | 6389 | */ |
51888ca2 | 6390 | static int build_sched_domains(const cpumask_t *cpu_map) |
1da177e4 LT |
6391 | { |
6392 | int i; | |
89c4710e | 6393 | struct sched_domain *sd; |
d1b55138 JH |
6394 | #ifdef CONFIG_NUMA |
6395 | struct sched_group **sched_group_nodes = NULL; | |
6711cab4 | 6396 | int sd_allnodes = 0; |
d1b55138 JH |
6397 | |
6398 | /* | |
6399 | * Allocate the per-node list of sched groups | |
6400 | */ | |
51888ca2 | 6401 | sched_group_nodes = kzalloc(sizeof(struct sched_group*)*MAX_NUMNODES, |
d3a5aa98 | 6402 | GFP_KERNEL); |
d1b55138 JH |
6403 | if (!sched_group_nodes) { |
6404 | printk(KERN_WARNING "Can not alloc sched group node list\n"); | |
51888ca2 | 6405 | return -ENOMEM; |
d1b55138 JH |
6406 | } |
6407 | sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes; | |
6408 | #endif | |
1da177e4 LT |
6409 | |
6410 | /* | |
1a20ff27 | 6411 | * Set up domains for cpus specified by the cpu_map. |
1da177e4 | 6412 | */ |
1a20ff27 | 6413 | for_each_cpu_mask(i, *cpu_map) { |
1da177e4 LT |
6414 | struct sched_domain *sd = NULL, *p; |
6415 | cpumask_t nodemask = node_to_cpumask(cpu_to_node(i)); | |
6416 | ||
1a20ff27 | 6417 | cpus_and(nodemask, nodemask, *cpu_map); |
1da177e4 LT |
6418 | |
6419 | #ifdef CONFIG_NUMA | |
d1b55138 | 6420 | if (cpus_weight(*cpu_map) |
9c1cfda2 JH |
6421 | > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) { |
6422 | sd = &per_cpu(allnodes_domains, i); | |
6423 | *sd = SD_ALLNODES_INIT; | |
6424 | sd->span = *cpu_map; | |
6711cab4 | 6425 | cpu_to_allnodes_group(i, cpu_map, &sd->groups); |
9c1cfda2 | 6426 | p = sd; |
6711cab4 | 6427 | sd_allnodes = 1; |
9c1cfda2 JH |
6428 | } else |
6429 | p = NULL; | |
6430 | ||
1da177e4 | 6431 | sd = &per_cpu(node_domains, i); |
1da177e4 | 6432 | *sd = SD_NODE_INIT; |
9c1cfda2 JH |
6433 | sd->span = sched_domain_node_span(cpu_to_node(i)); |
6434 | sd->parent = p; | |
1a848870 SS |
6435 | if (p) |
6436 | p->child = sd; | |
9c1cfda2 | 6437 | cpus_and(sd->span, sd->span, *cpu_map); |
1da177e4 LT |
6438 | #endif |
6439 | ||
6440 | p = sd; | |
6441 | sd = &per_cpu(phys_domains, i); | |
1da177e4 LT |
6442 | *sd = SD_CPU_INIT; |
6443 | sd->span = nodemask; | |
6444 | sd->parent = p; | |
1a848870 SS |
6445 | if (p) |
6446 | p->child = sd; | |
6711cab4 | 6447 | cpu_to_phys_group(i, cpu_map, &sd->groups); |
1da177e4 | 6448 | |
1e9f28fa SS |
6449 | #ifdef CONFIG_SCHED_MC |
6450 | p = sd; | |
6451 | sd = &per_cpu(core_domains, i); | |
1e9f28fa SS |
6452 | *sd = SD_MC_INIT; |
6453 | sd->span = cpu_coregroup_map(i); | |
6454 | cpus_and(sd->span, sd->span, *cpu_map); | |
6455 | sd->parent = p; | |
1a848870 | 6456 | p->child = sd; |
6711cab4 | 6457 | cpu_to_core_group(i, cpu_map, &sd->groups); |
1e9f28fa SS |
6458 | #endif |
6459 | ||
1da177e4 LT |
6460 | #ifdef CONFIG_SCHED_SMT |
6461 | p = sd; | |
6462 | sd = &per_cpu(cpu_domains, i); | |
1da177e4 LT |
6463 | *sd = SD_SIBLING_INIT; |
6464 | sd->span = cpu_sibling_map[i]; | |
1a20ff27 | 6465 | cpus_and(sd->span, sd->span, *cpu_map); |
1da177e4 | 6466 | sd->parent = p; |
1a848870 | 6467 | p->child = sd; |
6711cab4 | 6468 | cpu_to_cpu_group(i, cpu_map, &sd->groups); |
1da177e4 LT |
6469 | #endif |
6470 | } | |
6471 | ||
6472 | #ifdef CONFIG_SCHED_SMT | |
6473 | /* Set up CPU (sibling) groups */ | |
9c1cfda2 | 6474 | for_each_cpu_mask(i, *cpu_map) { |
1da177e4 | 6475 | cpumask_t this_sibling_map = cpu_sibling_map[i]; |
1a20ff27 | 6476 | cpus_and(this_sibling_map, this_sibling_map, *cpu_map); |
1da177e4 LT |
6477 | if (i != first_cpu(this_sibling_map)) |
6478 | continue; | |
6479 | ||
6711cab4 | 6480 | init_sched_build_groups(this_sibling_map, cpu_map, &cpu_to_cpu_group); |
1da177e4 LT |
6481 | } |
6482 | #endif | |
6483 | ||
1e9f28fa SS |
6484 | #ifdef CONFIG_SCHED_MC |
6485 | /* Set up multi-core groups */ | |
6486 | for_each_cpu_mask(i, *cpu_map) { | |
6487 | cpumask_t this_core_map = cpu_coregroup_map(i); | |
6488 | cpus_and(this_core_map, this_core_map, *cpu_map); | |
6489 | if (i != first_cpu(this_core_map)) | |
6490 | continue; | |
6711cab4 | 6491 | init_sched_build_groups(this_core_map, cpu_map, &cpu_to_core_group); |
1e9f28fa SS |
6492 | } |
6493 | #endif | |
6494 | ||
6495 | ||
1da177e4 LT |
6496 | /* Set up physical groups */ |
6497 | for (i = 0; i < MAX_NUMNODES; i++) { | |
6498 | cpumask_t nodemask = node_to_cpumask(i); | |
6499 | ||
1a20ff27 | 6500 | cpus_and(nodemask, nodemask, *cpu_map); |
1da177e4 LT |
6501 | if (cpus_empty(nodemask)) |
6502 | continue; | |
6503 | ||
6711cab4 | 6504 | init_sched_build_groups(nodemask, cpu_map, &cpu_to_phys_group); |
1da177e4 LT |
6505 | } |
6506 | ||
6507 | #ifdef CONFIG_NUMA | |
6508 | /* Set up node groups */ | |
6711cab4 SS |
6509 | if (sd_allnodes) |
6510 | init_sched_build_groups(*cpu_map, cpu_map, &cpu_to_allnodes_group); | |
9c1cfda2 JH |
6511 | |
6512 | for (i = 0; i < MAX_NUMNODES; i++) { | |
6513 | /* Set up node groups */ | |
6514 | struct sched_group *sg, *prev; | |
6515 | cpumask_t nodemask = node_to_cpumask(i); | |
6516 | cpumask_t domainspan; | |
6517 | cpumask_t covered = CPU_MASK_NONE; | |
6518 | int j; | |
6519 | ||
6520 | cpus_and(nodemask, nodemask, *cpu_map); | |
d1b55138 JH |
6521 | if (cpus_empty(nodemask)) { |
6522 | sched_group_nodes[i] = NULL; | |
9c1cfda2 | 6523 | continue; |
d1b55138 | 6524 | } |
9c1cfda2 JH |
6525 | |
6526 | domainspan = sched_domain_node_span(i); | |
6527 | cpus_and(domainspan, domainspan, *cpu_map); | |
6528 | ||
15f0b676 | 6529 | sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i); |
51888ca2 SV |
6530 | if (!sg) { |
6531 | printk(KERN_WARNING "Can not alloc domain group for " | |
6532 | "node %d\n", i); | |
6533 | goto error; | |
6534 | } | |
9c1cfda2 JH |
6535 | sched_group_nodes[i] = sg; |
6536 | for_each_cpu_mask(j, nodemask) { | |
6537 | struct sched_domain *sd; | |
6538 | sd = &per_cpu(node_domains, j); | |
6539 | sd->groups = sg; | |
9c1cfda2 JH |
6540 | } |
6541 | sg->cpu_power = 0; | |
6542 | sg->cpumask = nodemask; | |
51888ca2 | 6543 | sg->next = sg; |
9c1cfda2 JH |
6544 | cpus_or(covered, covered, nodemask); |
6545 | prev = sg; | |
6546 | ||
6547 | for (j = 0; j < MAX_NUMNODES; j++) { | |
6548 | cpumask_t tmp, notcovered; | |
6549 | int n = (i + j) % MAX_NUMNODES; | |
6550 | ||
6551 | cpus_complement(notcovered, covered); | |
6552 | cpus_and(tmp, notcovered, *cpu_map); | |
6553 | cpus_and(tmp, tmp, domainspan); | |
6554 | if (cpus_empty(tmp)) | |
6555 | break; | |
6556 | ||
6557 | nodemask = node_to_cpumask(n); | |
6558 | cpus_and(tmp, tmp, nodemask); | |
6559 | if (cpus_empty(tmp)) | |
6560 | continue; | |
6561 | ||
15f0b676 SV |
6562 | sg = kmalloc_node(sizeof(struct sched_group), |
6563 | GFP_KERNEL, i); | |
9c1cfda2 JH |
6564 | if (!sg) { |
6565 | printk(KERN_WARNING | |
6566 | "Can not alloc domain group for node %d\n", j); | |
51888ca2 | 6567 | goto error; |
9c1cfda2 JH |
6568 | } |
6569 | sg->cpu_power = 0; | |
6570 | sg->cpumask = tmp; | |
51888ca2 | 6571 | sg->next = prev->next; |
9c1cfda2 JH |
6572 | cpus_or(covered, covered, tmp); |
6573 | prev->next = sg; | |
6574 | prev = sg; | |
6575 | } | |
9c1cfda2 | 6576 | } |
1da177e4 LT |
6577 | #endif |
6578 | ||
6579 | /* Calculate CPU power for physical packages and nodes */ | |
5c45bf27 | 6580 | #ifdef CONFIG_SCHED_SMT |
1a20ff27 | 6581 | for_each_cpu_mask(i, *cpu_map) { |
1da177e4 | 6582 | sd = &per_cpu(cpu_domains, i); |
89c4710e | 6583 | init_sched_groups_power(i, sd); |
5c45bf27 | 6584 | } |
1da177e4 | 6585 | #endif |
1e9f28fa | 6586 | #ifdef CONFIG_SCHED_MC |
5c45bf27 | 6587 | for_each_cpu_mask(i, *cpu_map) { |
1e9f28fa | 6588 | sd = &per_cpu(core_domains, i); |
89c4710e | 6589 | init_sched_groups_power(i, sd); |
5c45bf27 SS |
6590 | } |
6591 | #endif | |
1e9f28fa | 6592 | |
5c45bf27 | 6593 | for_each_cpu_mask(i, *cpu_map) { |
1da177e4 | 6594 | sd = &per_cpu(phys_domains, i); |
89c4710e | 6595 | init_sched_groups_power(i, sd); |
1da177e4 LT |
6596 | } |
6597 | ||
9c1cfda2 | 6598 | #ifdef CONFIG_NUMA |
08069033 SS |
6599 | for (i = 0; i < MAX_NUMNODES; i++) |
6600 | init_numa_sched_groups_power(sched_group_nodes[i]); | |
9c1cfda2 | 6601 | |
6711cab4 SS |
6602 | if (sd_allnodes) { |
6603 | struct sched_group *sg; | |
f712c0c7 | 6604 | |
6711cab4 | 6605 | cpu_to_allnodes_group(first_cpu(*cpu_map), cpu_map, &sg); |
f712c0c7 SS |
6606 | init_numa_sched_groups_power(sg); |
6607 | } | |
9c1cfda2 JH |
6608 | #endif |
6609 | ||
1da177e4 | 6610 | /* Attach the domains */ |
1a20ff27 | 6611 | for_each_cpu_mask(i, *cpu_map) { |
1da177e4 LT |
6612 | struct sched_domain *sd; |
6613 | #ifdef CONFIG_SCHED_SMT | |
6614 | sd = &per_cpu(cpu_domains, i); | |
1e9f28fa SS |
6615 | #elif defined(CONFIG_SCHED_MC) |
6616 | sd = &per_cpu(core_domains, i); | |
1da177e4 LT |
6617 | #else |
6618 | sd = &per_cpu(phys_domains, i); | |
6619 | #endif | |
6620 | cpu_attach_domain(sd, i); | |
6621 | } | |
198e2f18 | 6622 | /* |
6623 | * Tune cache-hot values: | |
6624 | */ | |
6625 | calibrate_migration_costs(cpu_map); | |
51888ca2 SV |
6626 | |
6627 | return 0; | |
6628 | ||
a616058b | 6629 | #ifdef CONFIG_NUMA |
51888ca2 SV |
6630 | error: |
6631 | free_sched_groups(cpu_map); | |
6632 | return -ENOMEM; | |
a616058b | 6633 | #endif |
1da177e4 | 6634 | } |
1a20ff27 DG |
6635 | /* |
6636 | * Set up scheduler domains and groups. Callers must hold the hotplug lock. | |
6637 | */ | |
51888ca2 | 6638 | static int arch_init_sched_domains(const cpumask_t *cpu_map) |
1a20ff27 DG |
6639 | { |
6640 | cpumask_t cpu_default_map; | |
51888ca2 | 6641 | int err; |
1da177e4 | 6642 | |
1a20ff27 DG |
6643 | /* |
6644 | * Setup mask for cpus without special case scheduling requirements. | |
6645 | * For now this just excludes isolated cpus, but could be used to | |
6646 | * exclude other special cases in the future. | |
6647 | */ | |
6648 | cpus_andnot(cpu_default_map, *cpu_map, cpu_isolated_map); | |
6649 | ||
51888ca2 SV |
6650 | err = build_sched_domains(&cpu_default_map); |
6651 | ||
6652 | return err; | |
1a20ff27 DG |
6653 | } |
6654 | ||
6655 | static void arch_destroy_sched_domains(const cpumask_t *cpu_map) | |
1da177e4 | 6656 | { |
51888ca2 | 6657 | free_sched_groups(cpu_map); |
9c1cfda2 | 6658 | } |
1da177e4 | 6659 | |
1a20ff27 DG |
6660 | /* |
6661 | * Detach sched domains from a group of cpus specified in cpu_map | |
6662 | * These cpus will now be attached to the NULL domain | |
6663 | */ | |
858119e1 | 6664 | static void detach_destroy_domains(const cpumask_t *cpu_map) |
1a20ff27 DG |
6665 | { |
6666 | int i; | |
6667 | ||
6668 | for_each_cpu_mask(i, *cpu_map) | |
6669 | cpu_attach_domain(NULL, i); | |
6670 | synchronize_sched(); | |
6671 | arch_destroy_sched_domains(cpu_map); | |
6672 | } | |
6673 | ||
6674 | /* | |
6675 | * Partition sched domains as specified by the cpumasks below. | |
6676 | * This attaches all cpus from the cpumasks to the NULL domain, | |
6677 | * waits for a RCU quiescent period, recalculates sched | |
6678 | * domain information and then attaches them back to the | |
6679 | * correct sched domains | |
6680 | * Call with hotplug lock held | |
6681 | */ | |
51888ca2 | 6682 | int partition_sched_domains(cpumask_t *partition1, cpumask_t *partition2) |
1a20ff27 DG |
6683 | { |
6684 | cpumask_t change_map; | |
51888ca2 | 6685 | int err = 0; |
1a20ff27 DG |
6686 | |
6687 | cpus_and(*partition1, *partition1, cpu_online_map); | |
6688 | cpus_and(*partition2, *partition2, cpu_online_map); | |
6689 | cpus_or(change_map, *partition1, *partition2); | |
6690 | ||
6691 | /* Detach sched domains from all of the affected cpus */ | |
6692 | detach_destroy_domains(&change_map); | |
6693 | if (!cpus_empty(*partition1)) | |
51888ca2 SV |
6694 | err = build_sched_domains(partition1); |
6695 | if (!err && !cpus_empty(*partition2)) | |
6696 | err = build_sched_domains(partition2); | |
6697 | ||
6698 | return err; | |
1a20ff27 DG |
6699 | } |
6700 | ||
5c45bf27 SS |
6701 | #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) |
6702 | int arch_reinit_sched_domains(void) | |
6703 | { | |
6704 | int err; | |
6705 | ||
6706 | lock_cpu_hotplug(); | |
6707 | detach_destroy_domains(&cpu_online_map); | |
6708 | err = arch_init_sched_domains(&cpu_online_map); | |
6709 | unlock_cpu_hotplug(); | |
6710 | ||
6711 | return err; | |
6712 | } | |
6713 | ||
6714 | static ssize_t sched_power_savings_store(const char *buf, size_t count, int smt) | |
6715 | { | |
6716 | int ret; | |
6717 | ||
6718 | if (buf[0] != '0' && buf[0] != '1') | |
6719 | return -EINVAL; | |
6720 | ||
6721 | if (smt) | |
6722 | sched_smt_power_savings = (buf[0] == '1'); | |
6723 | else | |
6724 | sched_mc_power_savings = (buf[0] == '1'); | |
6725 | ||
6726 | ret = arch_reinit_sched_domains(); | |
6727 | ||
6728 | return ret ? ret : count; | |
6729 | } | |
6730 | ||
6731 | int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls) | |
6732 | { | |
6733 | int err = 0; | |
48f24c4d | 6734 | |
5c45bf27 SS |
6735 | #ifdef CONFIG_SCHED_SMT |
6736 | if (smt_capable()) | |
6737 | err = sysfs_create_file(&cls->kset.kobj, | |
6738 | &attr_sched_smt_power_savings.attr); | |
6739 | #endif | |
6740 | #ifdef CONFIG_SCHED_MC | |
6741 | if (!err && mc_capable()) | |
6742 | err = sysfs_create_file(&cls->kset.kobj, | |
6743 | &attr_sched_mc_power_savings.attr); | |
6744 | #endif | |
6745 | return err; | |
6746 | } | |
6747 | #endif | |
6748 | ||
6749 | #ifdef CONFIG_SCHED_MC | |
6750 | static ssize_t sched_mc_power_savings_show(struct sys_device *dev, char *page) | |
6751 | { | |
6752 | return sprintf(page, "%u\n", sched_mc_power_savings); | |
6753 | } | |
48f24c4d IM |
6754 | static ssize_t sched_mc_power_savings_store(struct sys_device *dev, |
6755 | const char *buf, size_t count) | |
5c45bf27 SS |
6756 | { |
6757 | return sched_power_savings_store(buf, count, 0); | |
6758 | } | |
6759 | SYSDEV_ATTR(sched_mc_power_savings, 0644, sched_mc_power_savings_show, | |
6760 | sched_mc_power_savings_store); | |
6761 | #endif | |
6762 | ||
6763 | #ifdef CONFIG_SCHED_SMT | |
6764 | static ssize_t sched_smt_power_savings_show(struct sys_device *dev, char *page) | |
6765 | { | |
6766 | return sprintf(page, "%u\n", sched_smt_power_savings); | |
6767 | } | |
48f24c4d IM |
6768 | static ssize_t sched_smt_power_savings_store(struct sys_device *dev, |
6769 | const char *buf, size_t count) | |
5c45bf27 SS |
6770 | { |
6771 | return sched_power_savings_store(buf, count, 1); | |
6772 | } | |
6773 | SYSDEV_ATTR(sched_smt_power_savings, 0644, sched_smt_power_savings_show, | |
6774 | sched_smt_power_savings_store); | |
6775 | #endif | |
6776 | ||
1da177e4 LT |
6777 | /* |
6778 | * Force a reinitialization of the sched domains hierarchy. The domains | |
6779 | * and groups cannot be updated in place without racing with the balancing | |
41c7ce9a | 6780 | * code, so we temporarily attach all running cpus to the NULL domain |
1da177e4 LT |
6781 | * which will prevent rebalancing while the sched domains are recalculated. |
6782 | */ | |
6783 | static int update_sched_domains(struct notifier_block *nfb, | |
6784 | unsigned long action, void *hcpu) | |
6785 | { | |
1da177e4 LT |
6786 | switch (action) { |
6787 | case CPU_UP_PREPARE: | |
6788 | case CPU_DOWN_PREPARE: | |
1a20ff27 | 6789 | detach_destroy_domains(&cpu_online_map); |
1da177e4 LT |
6790 | return NOTIFY_OK; |
6791 | ||
6792 | case CPU_UP_CANCELED: | |
6793 | case CPU_DOWN_FAILED: | |
6794 | case CPU_ONLINE: | |
6795 | case CPU_DEAD: | |
6796 | /* | |
6797 | * Fall through and re-initialise the domains. | |
6798 | */ | |
6799 | break; | |
6800 | default: | |
6801 | return NOTIFY_DONE; | |
6802 | } | |
6803 | ||
6804 | /* The hotplug lock is already held by cpu_up/cpu_down */ | |
1a20ff27 | 6805 | arch_init_sched_domains(&cpu_online_map); |
1da177e4 LT |
6806 | |
6807 | return NOTIFY_OK; | |
6808 | } | |
1da177e4 LT |
6809 | |
6810 | void __init sched_init_smp(void) | |
6811 | { | |
5c1e1767 NP |
6812 | cpumask_t non_isolated_cpus; |
6813 | ||
1da177e4 | 6814 | lock_cpu_hotplug(); |
1a20ff27 | 6815 | arch_init_sched_domains(&cpu_online_map); |
5c1e1767 NP |
6816 | cpus_andnot(non_isolated_cpus, cpu_online_map, cpu_isolated_map); |
6817 | if (cpus_empty(non_isolated_cpus)) | |
6818 | cpu_set(smp_processor_id(), non_isolated_cpus); | |
1da177e4 LT |
6819 | unlock_cpu_hotplug(); |
6820 | /* XXX: Theoretical race here - CPU may be hotplugged now */ | |
6821 | hotcpu_notifier(update_sched_domains, 0); | |
5c1e1767 NP |
6822 | |
6823 | /* Move init over to a non-isolated CPU */ | |
6824 | if (set_cpus_allowed(current, non_isolated_cpus) < 0) | |
6825 | BUG(); | |
1da177e4 LT |
6826 | } |
6827 | #else | |
6828 | void __init sched_init_smp(void) | |
6829 | { | |
6830 | } | |
6831 | #endif /* CONFIG_SMP */ | |
6832 | ||
6833 | int in_sched_functions(unsigned long addr) | |
6834 | { | |
6835 | /* Linker adds these: start and end of __sched functions */ | |
6836 | extern char __sched_text_start[], __sched_text_end[]; | |
48f24c4d | 6837 | |
1da177e4 LT |
6838 | return in_lock_functions(addr) || |
6839 | (addr >= (unsigned long)__sched_text_start | |
6840 | && addr < (unsigned long)__sched_text_end); | |
6841 | } | |
6842 | ||
6843 | void __init sched_init(void) | |
6844 | { | |
1da177e4 LT |
6845 | int i, j, k; |
6846 | ||
0a945022 | 6847 | for_each_possible_cpu(i) { |
70b97a7f IM |
6848 | struct prio_array *array; |
6849 | struct rq *rq; | |
1da177e4 LT |
6850 | |
6851 | rq = cpu_rq(i); | |
6852 | spin_lock_init(&rq->lock); | |
fcb99371 | 6853 | lockdep_set_class(&rq->lock, &rq->rq_lock_key); |
7897986b | 6854 | rq->nr_running = 0; |
1da177e4 LT |
6855 | rq->active = rq->arrays; |
6856 | rq->expired = rq->arrays + 1; | |
6857 | rq->best_expired_prio = MAX_PRIO; | |
6858 | ||
6859 | #ifdef CONFIG_SMP | |
41c7ce9a | 6860 | rq->sd = NULL; |
7897986b NP |
6861 | for (j = 1; j < 3; j++) |
6862 | rq->cpu_load[j] = 0; | |
1da177e4 LT |
6863 | rq->active_balance = 0; |
6864 | rq->push_cpu = 0; | |
0a2966b4 | 6865 | rq->cpu = i; |
1da177e4 LT |
6866 | rq->migration_thread = NULL; |
6867 | INIT_LIST_HEAD(&rq->migration_queue); | |
6868 | #endif | |
6869 | atomic_set(&rq->nr_iowait, 0); | |
6870 | ||
6871 | for (j = 0; j < 2; j++) { | |
6872 | array = rq->arrays + j; | |
6873 | for (k = 0; k < MAX_PRIO; k++) { | |
6874 | INIT_LIST_HEAD(array->queue + k); | |
6875 | __clear_bit(k, array->bitmap); | |
6876 | } | |
6877 | // delimiter for bitsearch | |
6878 | __set_bit(MAX_PRIO, array->bitmap); | |
6879 | } | |
6880 | } | |
6881 | ||
2dd73a4f | 6882 | set_load_weight(&init_task); |
b50f60ce | 6883 | |
c9819f45 CL |
6884 | #ifdef CONFIG_SMP |
6885 | open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL); | |
6886 | #endif | |
6887 | ||
b50f60ce HC |
6888 | #ifdef CONFIG_RT_MUTEXES |
6889 | plist_head_init(&init_task.pi_waiters, &init_task.pi_lock); | |
6890 | #endif | |
6891 | ||
1da177e4 LT |
6892 | /* |
6893 | * The boot idle thread does lazy MMU switching as well: | |
6894 | */ | |
6895 | atomic_inc(&init_mm.mm_count); | |
6896 | enter_lazy_tlb(&init_mm, current); | |
6897 | ||
6898 | /* | |
6899 | * Make us the idle thread. Technically, schedule() should not be | |
6900 | * called from this thread, however somewhere below it might be, | |
6901 | * but because we are the idle thread, we just pick up running again | |
6902 | * when this runqueue becomes "idle". | |
6903 | */ | |
6904 | init_idle(current, smp_processor_id()); | |
6905 | } | |
6906 | ||
6907 | #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP | |
6908 | void __might_sleep(char *file, int line) | |
6909 | { | |
48f24c4d | 6910 | #ifdef in_atomic |
1da177e4 LT |
6911 | static unsigned long prev_jiffy; /* ratelimiting */ |
6912 | ||
6913 | if ((in_atomic() || irqs_disabled()) && | |
6914 | system_state == SYSTEM_RUNNING && !oops_in_progress) { | |
6915 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) | |
6916 | return; | |
6917 | prev_jiffy = jiffies; | |
91368d73 | 6918 | printk(KERN_ERR "BUG: sleeping function called from invalid" |
1da177e4 LT |
6919 | " context at %s:%d\n", file, line); |
6920 | printk("in_atomic():%d, irqs_disabled():%d\n", | |
6921 | in_atomic(), irqs_disabled()); | |
a4c410f0 | 6922 | debug_show_held_locks(current); |
1da177e4 LT |
6923 | dump_stack(); |
6924 | } | |
6925 | #endif | |
6926 | } | |
6927 | EXPORT_SYMBOL(__might_sleep); | |
6928 | #endif | |
6929 | ||
6930 | #ifdef CONFIG_MAGIC_SYSRQ | |
6931 | void normalize_rt_tasks(void) | |
6932 | { | |
70b97a7f | 6933 | struct prio_array *array; |
1da177e4 | 6934 | struct task_struct *p; |
1da177e4 | 6935 | unsigned long flags; |
70b97a7f | 6936 | struct rq *rq; |
1da177e4 LT |
6937 | |
6938 | read_lock_irq(&tasklist_lock); | |
c96d145e | 6939 | for_each_process(p) { |
1da177e4 LT |
6940 | if (!rt_task(p)) |
6941 | continue; | |
6942 | ||
b29739f9 IM |
6943 | spin_lock_irqsave(&p->pi_lock, flags); |
6944 | rq = __task_rq_lock(p); | |
1da177e4 LT |
6945 | |
6946 | array = p->array; | |
6947 | if (array) | |
6948 | deactivate_task(p, task_rq(p)); | |
6949 | __setscheduler(p, SCHED_NORMAL, 0); | |
6950 | if (array) { | |
6951 | __activate_task(p, task_rq(p)); | |
6952 | resched_task(rq->curr); | |
6953 | } | |
6954 | ||
b29739f9 IM |
6955 | __task_rq_unlock(rq); |
6956 | spin_unlock_irqrestore(&p->pi_lock, flags); | |
1da177e4 LT |
6957 | } |
6958 | read_unlock_irq(&tasklist_lock); | |
6959 | } | |
6960 | ||
6961 | #endif /* CONFIG_MAGIC_SYSRQ */ | |
1df5c10a LT |
6962 | |
6963 | #ifdef CONFIG_IA64 | |
6964 | /* | |
6965 | * These functions are only useful for the IA64 MCA handling. | |
6966 | * | |
6967 | * They can only be called when the whole system has been | |
6968 | * stopped - every CPU needs to be quiescent, and no scheduling | |
6969 | * activity can take place. Using them for anything else would | |
6970 | * be a serious bug, and as a result, they aren't even visible | |
6971 | * under any other configuration. | |
6972 | */ | |
6973 | ||
6974 | /** | |
6975 | * curr_task - return the current task for a given cpu. | |
6976 | * @cpu: the processor in question. | |
6977 | * | |
6978 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6979 | */ | |
36c8b586 | 6980 | struct task_struct *curr_task(int cpu) |
1df5c10a LT |
6981 | { |
6982 | return cpu_curr(cpu); | |
6983 | } | |
6984 | ||
6985 | /** | |
6986 | * set_curr_task - set the current task for a given cpu. | |
6987 | * @cpu: the processor in question. | |
6988 | * @p: the task pointer to set. | |
6989 | * | |
6990 | * Description: This function must only be used when non-maskable interrupts | |
6991 | * are serviced on a separate stack. It allows the architecture to switch the | |
6992 | * notion of the current task on a cpu in a non-blocking manner. This function | |
6993 | * must be called with all CPU's synchronized, and interrupts disabled, the | |
6994 | * and caller must save the original value of the current task (see | |
6995 | * curr_task() above) and restore that value before reenabling interrupts and | |
6996 | * re-starting the system. | |
6997 | * | |
6998 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6999 | */ | |
36c8b586 | 7000 | void set_curr_task(int cpu, struct task_struct *p) |
1df5c10a LT |
7001 | { |
7002 | cpu_curr(cpu) = p; | |
7003 | } | |
7004 | ||
7005 | #endif |