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Commit | Line | Data |
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1da177e4 | 1 | /* |
391e43da | 2 | * kernel/sched/core.c |
1da177e4 | 3 | * |
d1ccc66d | 4 | * Core kernel scheduler code and related syscalls |
1da177e4 LT |
5 | * |
6 | * Copyright (C) 1991-2002 Linus Torvalds | |
1da177e4 | 7 | */ |
004172bd | 8 | #include <linux/sched.h> |
e6017571 | 9 | #include <linux/sched/clock.h> |
ae7e81c0 | 10 | #include <uapi/linux/sched/types.h> |
4f17722c | 11 | #include <linux/sched/loadavg.h> |
ef8bd77f | 12 | #include <linux/sched/hotplug.h> |
5822a454 | 13 | #include <linux/wait_bit.h> |
1da177e4 | 14 | #include <linux/cpuset.h> |
0ff92245 | 15 | #include <linux/delayacct.h> |
f1c6f1a7 | 16 | #include <linux/init_task.h> |
91d1aa43 | 17 | #include <linux/context_tracking.h> |
f9411ebe | 18 | #include <linux/rcupdate_wait.h> |
004172bd IM |
19 | |
20 | #include <linux/blkdev.h> | |
21 | #include <linux/kprobes.h> | |
22 | #include <linux/mmu_context.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/nmi.h> | |
6075620b | 25 | #include <linux/prefetch.h> |
004172bd IM |
26 | #include <linux/profile.h> |
27 | #include <linux/security.h> | |
28 | #include <linux/syscalls.h> | |
78634061 | 29 | #include <linux/sched/isolation.h> |
1da177e4 | 30 | |
96f951ed | 31 | #include <asm/switch_to.h> |
5517d86b | 32 | #include <asm/tlb.h> |
fd4a61e0 MB |
33 | #ifdef CONFIG_PARAVIRT |
34 | #include <asm/paravirt.h> | |
35 | #endif | |
1da177e4 | 36 | |
029632fb | 37 | #include "sched.h" |
ea138446 | 38 | #include "../workqueue_internal.h" |
29d5e047 | 39 | #include "../smpboot.h" |
6e0534f2 | 40 | |
a8d154b0 | 41 | #define CREATE_TRACE_POINTS |
ad8d75ff | 42 | #include <trace/events/sched.h> |
a8d154b0 | 43 | |
029632fb | 44 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); |
dc61b1d6 | 45 | |
bf5c91ba IM |
46 | /* |
47 | * Debugging: various feature bits | |
48 | */ | |
f00b45c1 | 49 | |
f00b45c1 PZ |
50 | #define SCHED_FEAT(name, enabled) \ |
51 | (1UL << __SCHED_FEAT_##name) * enabled | | |
52 | ||
bf5c91ba | 53 | const_debug unsigned int sysctl_sched_features = |
391e43da | 54 | #include "features.h" |
f00b45c1 PZ |
55 | 0; |
56 | ||
57 | #undef SCHED_FEAT | |
58 | ||
b82d9fdd PZ |
59 | /* |
60 | * Number of tasks to iterate in a single balance run. | |
61 | * Limited because this is done with IRQs disabled. | |
62 | */ | |
63 | const_debug unsigned int sysctl_sched_nr_migrate = 32; | |
64 | ||
e9e9250b PZ |
65 | /* |
66 | * period over which we average the RT time consumption, measured | |
67 | * in ms. | |
68 | * | |
69 | * default: 1s | |
70 | */ | |
71 | const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; | |
72 | ||
fa85ae24 | 73 | /* |
d1ccc66d | 74 | * period over which we measure -rt task CPU usage in us. |
fa85ae24 PZ |
75 | * default: 1s |
76 | */ | |
9f0c1e56 | 77 | unsigned int sysctl_sched_rt_period = 1000000; |
fa85ae24 | 78 | |
029632fb | 79 | __read_mostly int scheduler_running; |
6892b75e | 80 | |
9f0c1e56 PZ |
81 | /* |
82 | * part of the period that we allow rt tasks to run in us. | |
83 | * default: 0.95s | |
84 | */ | |
85 | int sysctl_sched_rt_runtime = 950000; | |
fa85ae24 | 86 | |
3e71a462 PZ |
87 | /* |
88 | * __task_rq_lock - lock the rq @p resides on. | |
89 | */ | |
eb580751 | 90 | struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
3e71a462 PZ |
91 | __acquires(rq->lock) |
92 | { | |
93 | struct rq *rq; | |
94 | ||
95 | lockdep_assert_held(&p->pi_lock); | |
96 | ||
97 | for (;;) { | |
98 | rq = task_rq(p); | |
99 | raw_spin_lock(&rq->lock); | |
100 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
d8ac8971 | 101 | rq_pin_lock(rq, rf); |
3e71a462 PZ |
102 | return rq; |
103 | } | |
104 | raw_spin_unlock(&rq->lock); | |
105 | ||
106 | while (unlikely(task_on_rq_migrating(p))) | |
107 | cpu_relax(); | |
108 | } | |
109 | } | |
110 | ||
111 | /* | |
112 | * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. | |
113 | */ | |
eb580751 | 114 | struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
3e71a462 PZ |
115 | __acquires(p->pi_lock) |
116 | __acquires(rq->lock) | |
117 | { | |
118 | struct rq *rq; | |
119 | ||
120 | for (;;) { | |
eb580751 | 121 | raw_spin_lock_irqsave(&p->pi_lock, rf->flags); |
3e71a462 PZ |
122 | rq = task_rq(p); |
123 | raw_spin_lock(&rq->lock); | |
124 | /* | |
125 | * move_queued_task() task_rq_lock() | |
126 | * | |
127 | * ACQUIRE (rq->lock) | |
128 | * [S] ->on_rq = MIGRATING [L] rq = task_rq() | |
129 | * WMB (__set_task_cpu()) ACQUIRE (rq->lock); | |
130 | * [S] ->cpu = new_cpu [L] task_rq() | |
131 | * [L] ->on_rq | |
132 | * RELEASE (rq->lock) | |
133 | * | |
134 | * If we observe the old cpu in task_rq_lock, the acquire of | |
135 | * the old rq->lock will fully serialize against the stores. | |
136 | * | |
d1ccc66d | 137 | * If we observe the new CPU in task_rq_lock, the acquire will |
3e71a462 PZ |
138 | * pair with the WMB to ensure we must then also see migrating. |
139 | */ | |
140 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
d8ac8971 | 141 | rq_pin_lock(rq, rf); |
3e71a462 PZ |
142 | return rq; |
143 | } | |
144 | raw_spin_unlock(&rq->lock); | |
eb580751 | 145 | raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); |
3e71a462 PZ |
146 | |
147 | while (unlikely(task_on_rq_migrating(p))) | |
148 | cpu_relax(); | |
149 | } | |
150 | } | |
151 | ||
535b9552 IM |
152 | /* |
153 | * RQ-clock updating methods: | |
154 | */ | |
155 | ||
156 | static void update_rq_clock_task(struct rq *rq, s64 delta) | |
157 | { | |
158 | /* | |
159 | * In theory, the compile should just see 0 here, and optimize out the call | |
160 | * to sched_rt_avg_update. But I don't trust it... | |
161 | */ | |
162 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
163 | s64 steal = 0, irq_delta = 0; | |
164 | #endif | |
165 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING | |
166 | irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; | |
167 | ||
168 | /* | |
169 | * Since irq_time is only updated on {soft,}irq_exit, we might run into | |
170 | * this case when a previous update_rq_clock() happened inside a | |
171 | * {soft,}irq region. | |
172 | * | |
173 | * When this happens, we stop ->clock_task and only update the | |
174 | * prev_irq_time stamp to account for the part that fit, so that a next | |
175 | * update will consume the rest. This ensures ->clock_task is | |
176 | * monotonic. | |
177 | * | |
178 | * It does however cause some slight miss-attribution of {soft,}irq | |
179 | * time, a more accurate solution would be to update the irq_time using | |
180 | * the current rq->clock timestamp, except that would require using | |
181 | * atomic ops. | |
182 | */ | |
183 | if (irq_delta > delta) | |
184 | irq_delta = delta; | |
185 | ||
186 | rq->prev_irq_time += irq_delta; | |
187 | delta -= irq_delta; | |
188 | #endif | |
189 | #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING | |
190 | if (static_key_false((¶virt_steal_rq_enabled))) { | |
191 | steal = paravirt_steal_clock(cpu_of(rq)); | |
192 | steal -= rq->prev_steal_time_rq; | |
193 | ||
194 | if (unlikely(steal > delta)) | |
195 | steal = delta; | |
196 | ||
197 | rq->prev_steal_time_rq += steal; | |
198 | delta -= steal; | |
199 | } | |
200 | #endif | |
201 | ||
202 | rq->clock_task += delta; | |
203 | ||
204 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
205 | if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) | |
206 | sched_rt_avg_update(rq, irq_delta + steal); | |
207 | #endif | |
208 | } | |
209 | ||
210 | void update_rq_clock(struct rq *rq) | |
211 | { | |
212 | s64 delta; | |
213 | ||
214 | lockdep_assert_held(&rq->lock); | |
215 | ||
216 | if (rq->clock_update_flags & RQCF_ACT_SKIP) | |
217 | return; | |
218 | ||
219 | #ifdef CONFIG_SCHED_DEBUG | |
26ae58d2 PZ |
220 | if (sched_feat(WARN_DOUBLE_CLOCK)) |
221 | SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); | |
535b9552 IM |
222 | rq->clock_update_flags |= RQCF_UPDATED; |
223 | #endif | |
26ae58d2 | 224 | |
535b9552 IM |
225 | delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; |
226 | if (delta < 0) | |
227 | return; | |
228 | rq->clock += delta; | |
229 | update_rq_clock_task(rq, delta); | |
230 | } | |
231 | ||
232 | ||
8f4d37ec PZ |
233 | #ifdef CONFIG_SCHED_HRTICK |
234 | /* | |
235 | * Use HR-timers to deliver accurate preemption points. | |
8f4d37ec | 236 | */ |
8f4d37ec | 237 | |
8f4d37ec PZ |
238 | static void hrtick_clear(struct rq *rq) |
239 | { | |
240 | if (hrtimer_active(&rq->hrtick_timer)) | |
241 | hrtimer_cancel(&rq->hrtick_timer); | |
242 | } | |
243 | ||
8f4d37ec PZ |
244 | /* |
245 | * High-resolution timer tick. | |
246 | * Runs from hardirq context with interrupts disabled. | |
247 | */ | |
248 | static enum hrtimer_restart hrtick(struct hrtimer *timer) | |
249 | { | |
250 | struct rq *rq = container_of(timer, struct rq, hrtick_timer); | |
8a8c69c3 | 251 | struct rq_flags rf; |
8f4d37ec PZ |
252 | |
253 | WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); | |
254 | ||
8a8c69c3 | 255 | rq_lock(rq, &rf); |
3e51f33f | 256 | update_rq_clock(rq); |
8f4d37ec | 257 | rq->curr->sched_class->task_tick(rq, rq->curr, 1); |
8a8c69c3 | 258 | rq_unlock(rq, &rf); |
8f4d37ec PZ |
259 | |
260 | return HRTIMER_NORESTART; | |
261 | } | |
262 | ||
95e904c7 | 263 | #ifdef CONFIG_SMP |
971ee28c | 264 | |
4961b6e1 | 265 | static void __hrtick_restart(struct rq *rq) |
971ee28c PZ |
266 | { |
267 | struct hrtimer *timer = &rq->hrtick_timer; | |
971ee28c | 268 | |
4961b6e1 | 269 | hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED); |
971ee28c PZ |
270 | } |
271 | ||
31656519 PZ |
272 | /* |
273 | * called from hardirq (IPI) context | |
274 | */ | |
275 | static void __hrtick_start(void *arg) | |
b328ca18 | 276 | { |
31656519 | 277 | struct rq *rq = arg; |
8a8c69c3 | 278 | struct rq_flags rf; |
b328ca18 | 279 | |
8a8c69c3 | 280 | rq_lock(rq, &rf); |
971ee28c | 281 | __hrtick_restart(rq); |
31656519 | 282 | rq->hrtick_csd_pending = 0; |
8a8c69c3 | 283 | rq_unlock(rq, &rf); |
b328ca18 PZ |
284 | } |
285 | ||
31656519 PZ |
286 | /* |
287 | * Called to set the hrtick timer state. | |
288 | * | |
289 | * called with rq->lock held and irqs disabled | |
290 | */ | |
029632fb | 291 | void hrtick_start(struct rq *rq, u64 delay) |
b328ca18 | 292 | { |
31656519 | 293 | struct hrtimer *timer = &rq->hrtick_timer; |
177ef2a6 | 294 | ktime_t time; |
295 | s64 delta; | |
296 | ||
297 | /* | |
298 | * Don't schedule slices shorter than 10000ns, that just | |
299 | * doesn't make sense and can cause timer DoS. | |
300 | */ | |
301 | delta = max_t(s64, delay, 10000LL); | |
302 | time = ktime_add_ns(timer->base->get_time(), delta); | |
b328ca18 | 303 | |
cc584b21 | 304 | hrtimer_set_expires(timer, time); |
31656519 PZ |
305 | |
306 | if (rq == this_rq()) { | |
971ee28c | 307 | __hrtick_restart(rq); |
31656519 | 308 | } else if (!rq->hrtick_csd_pending) { |
c46fff2a | 309 | smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); |
31656519 PZ |
310 | rq->hrtick_csd_pending = 1; |
311 | } | |
b328ca18 PZ |
312 | } |
313 | ||
31656519 PZ |
314 | #else |
315 | /* | |
316 | * Called to set the hrtick timer state. | |
317 | * | |
318 | * called with rq->lock held and irqs disabled | |
319 | */ | |
029632fb | 320 | void hrtick_start(struct rq *rq, u64 delay) |
31656519 | 321 | { |
86893335 WL |
322 | /* |
323 | * Don't schedule slices shorter than 10000ns, that just | |
324 | * doesn't make sense. Rely on vruntime for fairness. | |
325 | */ | |
326 | delay = max_t(u64, delay, 10000LL); | |
4961b6e1 TG |
327 | hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), |
328 | HRTIMER_MODE_REL_PINNED); | |
31656519 | 329 | } |
31656519 | 330 | #endif /* CONFIG_SMP */ |
8f4d37ec | 331 | |
31656519 | 332 | static void init_rq_hrtick(struct rq *rq) |
8f4d37ec | 333 | { |
31656519 PZ |
334 | #ifdef CONFIG_SMP |
335 | rq->hrtick_csd_pending = 0; | |
8f4d37ec | 336 | |
31656519 PZ |
337 | rq->hrtick_csd.flags = 0; |
338 | rq->hrtick_csd.func = __hrtick_start; | |
339 | rq->hrtick_csd.info = rq; | |
340 | #endif | |
8f4d37ec | 341 | |
31656519 PZ |
342 | hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
343 | rq->hrtick_timer.function = hrtick; | |
8f4d37ec | 344 | } |
006c75f1 | 345 | #else /* CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
346 | static inline void hrtick_clear(struct rq *rq) |
347 | { | |
348 | } | |
349 | ||
8f4d37ec PZ |
350 | static inline void init_rq_hrtick(struct rq *rq) |
351 | { | |
352 | } | |
006c75f1 | 353 | #endif /* CONFIG_SCHED_HRTICK */ |
8f4d37ec | 354 | |
5529578a FW |
355 | /* |
356 | * cmpxchg based fetch_or, macro so it works for different integer types | |
357 | */ | |
358 | #define fetch_or(ptr, mask) \ | |
359 | ({ \ | |
360 | typeof(ptr) _ptr = (ptr); \ | |
361 | typeof(mask) _mask = (mask); \ | |
362 | typeof(*_ptr) _old, _val = *_ptr; \ | |
363 | \ | |
364 | for (;;) { \ | |
365 | _old = cmpxchg(_ptr, _val, _val | _mask); \ | |
366 | if (_old == _val) \ | |
367 | break; \ | |
368 | _val = _old; \ | |
369 | } \ | |
370 | _old; \ | |
371 | }) | |
372 | ||
e3baac47 | 373 | #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) |
fd99f91a PZ |
374 | /* |
375 | * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, | |
376 | * this avoids any races wrt polling state changes and thereby avoids | |
377 | * spurious IPIs. | |
378 | */ | |
379 | static bool set_nr_and_not_polling(struct task_struct *p) | |
380 | { | |
381 | struct thread_info *ti = task_thread_info(p); | |
382 | return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); | |
383 | } | |
e3baac47 PZ |
384 | |
385 | /* | |
386 | * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. | |
387 | * | |
388 | * If this returns true, then the idle task promises to call | |
389 | * sched_ttwu_pending() and reschedule soon. | |
390 | */ | |
391 | static bool set_nr_if_polling(struct task_struct *p) | |
392 | { | |
393 | struct thread_info *ti = task_thread_info(p); | |
316c1608 | 394 | typeof(ti->flags) old, val = READ_ONCE(ti->flags); |
e3baac47 PZ |
395 | |
396 | for (;;) { | |
397 | if (!(val & _TIF_POLLING_NRFLAG)) | |
398 | return false; | |
399 | if (val & _TIF_NEED_RESCHED) | |
400 | return true; | |
401 | old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); | |
402 | if (old == val) | |
403 | break; | |
404 | val = old; | |
405 | } | |
406 | return true; | |
407 | } | |
408 | ||
fd99f91a PZ |
409 | #else |
410 | static bool set_nr_and_not_polling(struct task_struct *p) | |
411 | { | |
412 | set_tsk_need_resched(p); | |
413 | return true; | |
414 | } | |
e3baac47 PZ |
415 | |
416 | #ifdef CONFIG_SMP | |
417 | static bool set_nr_if_polling(struct task_struct *p) | |
418 | { | |
419 | return false; | |
420 | } | |
421 | #endif | |
fd99f91a PZ |
422 | #endif |
423 | ||
76751049 PZ |
424 | void wake_q_add(struct wake_q_head *head, struct task_struct *task) |
425 | { | |
426 | struct wake_q_node *node = &task->wake_q; | |
427 | ||
428 | /* | |
429 | * Atomically grab the task, if ->wake_q is !nil already it means | |
430 | * its already queued (either by us or someone else) and will get the | |
431 | * wakeup due to that. | |
432 | * | |
433 | * This cmpxchg() implies a full barrier, which pairs with the write | |
58fe9c46 | 434 | * barrier implied by the wakeup in wake_up_q(). |
76751049 PZ |
435 | */ |
436 | if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL)) | |
437 | return; | |
438 | ||
439 | get_task_struct(task); | |
440 | ||
441 | /* | |
442 | * The head is context local, there can be no concurrency. | |
443 | */ | |
444 | *head->lastp = node; | |
445 | head->lastp = &node->next; | |
446 | } | |
447 | ||
448 | void wake_up_q(struct wake_q_head *head) | |
449 | { | |
450 | struct wake_q_node *node = head->first; | |
451 | ||
452 | while (node != WAKE_Q_TAIL) { | |
453 | struct task_struct *task; | |
454 | ||
455 | task = container_of(node, struct task_struct, wake_q); | |
456 | BUG_ON(!task); | |
d1ccc66d | 457 | /* Task can safely be re-inserted now: */ |
76751049 PZ |
458 | node = node->next; |
459 | task->wake_q.next = NULL; | |
460 | ||
461 | /* | |
462 | * wake_up_process() implies a wmb() to pair with the queueing | |
463 | * in wake_q_add() so as not to miss wakeups. | |
464 | */ | |
465 | wake_up_process(task); | |
466 | put_task_struct(task); | |
467 | } | |
468 | } | |
469 | ||
c24d20db | 470 | /* |
8875125e | 471 | * resched_curr - mark rq's current task 'to be rescheduled now'. |
c24d20db IM |
472 | * |
473 | * On UP this means the setting of the need_resched flag, on SMP it | |
474 | * might also involve a cross-CPU call to trigger the scheduler on | |
475 | * the target CPU. | |
476 | */ | |
8875125e | 477 | void resched_curr(struct rq *rq) |
c24d20db | 478 | { |
8875125e | 479 | struct task_struct *curr = rq->curr; |
c24d20db IM |
480 | int cpu; |
481 | ||
8875125e | 482 | lockdep_assert_held(&rq->lock); |
c24d20db | 483 | |
8875125e | 484 | if (test_tsk_need_resched(curr)) |
c24d20db IM |
485 | return; |
486 | ||
8875125e | 487 | cpu = cpu_of(rq); |
fd99f91a | 488 | |
f27dde8d | 489 | if (cpu == smp_processor_id()) { |
8875125e | 490 | set_tsk_need_resched(curr); |
f27dde8d | 491 | set_preempt_need_resched(); |
c24d20db | 492 | return; |
f27dde8d | 493 | } |
c24d20db | 494 | |
8875125e | 495 | if (set_nr_and_not_polling(curr)) |
c24d20db | 496 | smp_send_reschedule(cpu); |
dfc68f29 AL |
497 | else |
498 | trace_sched_wake_idle_without_ipi(cpu); | |
c24d20db IM |
499 | } |
500 | ||
029632fb | 501 | void resched_cpu(int cpu) |
c24d20db IM |
502 | { |
503 | struct rq *rq = cpu_rq(cpu); | |
504 | unsigned long flags; | |
505 | ||
05fa785c | 506 | if (!raw_spin_trylock_irqsave(&rq->lock, flags)) |
c24d20db | 507 | return; |
8875125e | 508 | resched_curr(rq); |
05fa785c | 509 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
c24d20db | 510 | } |
06d8308c | 511 | |
b021fe3e | 512 | #ifdef CONFIG_SMP |
3451d024 | 513 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 | 514 | /* |
d1ccc66d IM |
515 | * In the semi idle case, use the nearest busy CPU for migrating timers |
516 | * from an idle CPU. This is good for power-savings. | |
83cd4fe2 VP |
517 | * |
518 | * We don't do similar optimization for completely idle system, as | |
d1ccc66d IM |
519 | * selecting an idle CPU will add more delays to the timers than intended |
520 | * (as that CPU's timer base may not be uptodate wrt jiffies etc). | |
83cd4fe2 | 521 | */ |
bc7a34b8 | 522 | int get_nohz_timer_target(void) |
83cd4fe2 | 523 | { |
bc7a34b8 | 524 | int i, cpu = smp_processor_id(); |
83cd4fe2 VP |
525 | struct sched_domain *sd; |
526 | ||
de201559 | 527 | if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
6201b4d6 VK |
528 | return cpu; |
529 | ||
057f3fad | 530 | rcu_read_lock(); |
83cd4fe2 | 531 | for_each_domain(cpu, sd) { |
057f3fad | 532 | for_each_cpu(i, sched_domain_span(sd)) { |
44496922 WL |
533 | if (cpu == i) |
534 | continue; | |
535 | ||
de201559 | 536 | if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) { |
057f3fad PZ |
537 | cpu = i; |
538 | goto unlock; | |
539 | } | |
540 | } | |
83cd4fe2 | 541 | } |
9642d18e | 542 | |
de201559 FW |
543 | if (!housekeeping_cpu(cpu, HK_FLAG_TIMER)) |
544 | cpu = housekeeping_any_cpu(HK_FLAG_TIMER); | |
057f3fad PZ |
545 | unlock: |
546 | rcu_read_unlock(); | |
83cd4fe2 VP |
547 | return cpu; |
548 | } | |
d1ccc66d | 549 | |
06d8308c TG |
550 | /* |
551 | * When add_timer_on() enqueues a timer into the timer wheel of an | |
552 | * idle CPU then this timer might expire before the next timer event | |
553 | * which is scheduled to wake up that CPU. In case of a completely | |
554 | * idle system the next event might even be infinite time into the | |
555 | * future. wake_up_idle_cpu() ensures that the CPU is woken up and | |
556 | * leaves the inner idle loop so the newly added timer is taken into | |
557 | * account when the CPU goes back to idle and evaluates the timer | |
558 | * wheel for the next timer event. | |
559 | */ | |
1c20091e | 560 | static void wake_up_idle_cpu(int cpu) |
06d8308c TG |
561 | { |
562 | struct rq *rq = cpu_rq(cpu); | |
563 | ||
564 | if (cpu == smp_processor_id()) | |
565 | return; | |
566 | ||
67b9ca70 | 567 | if (set_nr_and_not_polling(rq->idle)) |
06d8308c | 568 | smp_send_reschedule(cpu); |
dfc68f29 AL |
569 | else |
570 | trace_sched_wake_idle_without_ipi(cpu); | |
45bf76df IM |
571 | } |
572 | ||
c5bfece2 | 573 | static bool wake_up_full_nohz_cpu(int cpu) |
1c20091e | 574 | { |
53c5fa16 FW |
575 | /* |
576 | * We just need the target to call irq_exit() and re-evaluate | |
577 | * the next tick. The nohz full kick at least implies that. | |
578 | * If needed we can still optimize that later with an | |
579 | * empty IRQ. | |
580 | */ | |
379d9ecb PM |
581 | if (cpu_is_offline(cpu)) |
582 | return true; /* Don't try to wake offline CPUs. */ | |
c5bfece2 | 583 | if (tick_nohz_full_cpu(cpu)) { |
1c20091e FW |
584 | if (cpu != smp_processor_id() || |
585 | tick_nohz_tick_stopped()) | |
53c5fa16 | 586 | tick_nohz_full_kick_cpu(cpu); |
1c20091e FW |
587 | return true; |
588 | } | |
589 | ||
590 | return false; | |
591 | } | |
592 | ||
379d9ecb PM |
593 | /* |
594 | * Wake up the specified CPU. If the CPU is going offline, it is the | |
595 | * caller's responsibility to deal with the lost wakeup, for example, | |
596 | * by hooking into the CPU_DEAD notifier like timers and hrtimers do. | |
597 | */ | |
1c20091e FW |
598 | void wake_up_nohz_cpu(int cpu) |
599 | { | |
c5bfece2 | 600 | if (!wake_up_full_nohz_cpu(cpu)) |
1c20091e FW |
601 | wake_up_idle_cpu(cpu); |
602 | } | |
603 | ||
ca38062e | 604 | static inline bool got_nohz_idle_kick(void) |
45bf76df | 605 | { |
1c792db7 | 606 | int cpu = smp_processor_id(); |
873b4c65 VG |
607 | |
608 | if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) | |
609 | return false; | |
610 | ||
611 | if (idle_cpu(cpu) && !need_resched()) | |
612 | return true; | |
613 | ||
614 | /* | |
615 | * We can't run Idle Load Balance on this CPU for this time so we | |
616 | * cancel it and clear NOHZ_BALANCE_KICK | |
617 | */ | |
618 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); | |
619 | return false; | |
45bf76df IM |
620 | } |
621 | ||
3451d024 | 622 | #else /* CONFIG_NO_HZ_COMMON */ |
45bf76df | 623 | |
ca38062e | 624 | static inline bool got_nohz_idle_kick(void) |
2069dd75 | 625 | { |
ca38062e | 626 | return false; |
2069dd75 PZ |
627 | } |
628 | ||
3451d024 | 629 | #endif /* CONFIG_NO_HZ_COMMON */ |
d842de87 | 630 | |
ce831b38 | 631 | #ifdef CONFIG_NO_HZ_FULL |
76d92ac3 | 632 | bool sched_can_stop_tick(struct rq *rq) |
ce831b38 | 633 | { |
76d92ac3 FW |
634 | int fifo_nr_running; |
635 | ||
636 | /* Deadline tasks, even if single, need the tick */ | |
637 | if (rq->dl.dl_nr_running) | |
638 | return false; | |
639 | ||
1e78cdbd | 640 | /* |
2548d546 PZ |
641 | * If there are more than one RR tasks, we need the tick to effect the |
642 | * actual RR behaviour. | |
1e78cdbd | 643 | */ |
76d92ac3 FW |
644 | if (rq->rt.rr_nr_running) { |
645 | if (rq->rt.rr_nr_running == 1) | |
646 | return true; | |
647 | else | |
648 | return false; | |
1e78cdbd RR |
649 | } |
650 | ||
2548d546 PZ |
651 | /* |
652 | * If there's no RR tasks, but FIFO tasks, we can skip the tick, no | |
653 | * forced preemption between FIFO tasks. | |
654 | */ | |
655 | fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; | |
656 | if (fifo_nr_running) | |
657 | return true; | |
658 | ||
659 | /* | |
660 | * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; | |
661 | * if there's more than one we need the tick for involuntary | |
662 | * preemption. | |
663 | */ | |
664 | if (rq->nr_running > 1) | |
541b8264 | 665 | return false; |
ce831b38 | 666 | |
541b8264 | 667 | return true; |
ce831b38 FW |
668 | } |
669 | #endif /* CONFIG_NO_HZ_FULL */ | |
d842de87 | 670 | |
029632fb | 671 | void sched_avg_update(struct rq *rq) |
18d95a28 | 672 | { |
e9e9250b PZ |
673 | s64 period = sched_avg_period(); |
674 | ||
78becc27 | 675 | while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { |
0d98bb26 WD |
676 | /* |
677 | * Inline assembly required to prevent the compiler | |
678 | * optimising this loop into a divmod call. | |
679 | * See __iter_div_u64_rem() for another example of this. | |
680 | */ | |
681 | asm("" : "+rm" (rq->age_stamp)); | |
e9e9250b PZ |
682 | rq->age_stamp += period; |
683 | rq->rt_avg /= 2; | |
684 | } | |
18d95a28 PZ |
685 | } |
686 | ||
6d6bc0ad | 687 | #endif /* CONFIG_SMP */ |
18d95a28 | 688 | |
a790de99 PT |
689 | #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ |
690 | (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) | |
c09595f6 | 691 | /* |
8277434e PT |
692 | * Iterate task_group tree rooted at *from, calling @down when first entering a |
693 | * node and @up when leaving it for the final time. | |
694 | * | |
695 | * Caller must hold rcu_lock or sufficient equivalent. | |
c09595f6 | 696 | */ |
029632fb | 697 | int walk_tg_tree_from(struct task_group *from, |
8277434e | 698 | tg_visitor down, tg_visitor up, void *data) |
c09595f6 PZ |
699 | { |
700 | struct task_group *parent, *child; | |
eb755805 | 701 | int ret; |
c09595f6 | 702 | |
8277434e PT |
703 | parent = from; |
704 | ||
c09595f6 | 705 | down: |
eb755805 PZ |
706 | ret = (*down)(parent, data); |
707 | if (ret) | |
8277434e | 708 | goto out; |
c09595f6 PZ |
709 | list_for_each_entry_rcu(child, &parent->children, siblings) { |
710 | parent = child; | |
711 | goto down; | |
712 | ||
713 | up: | |
714 | continue; | |
715 | } | |
eb755805 | 716 | ret = (*up)(parent, data); |
8277434e PT |
717 | if (ret || parent == from) |
718 | goto out; | |
c09595f6 PZ |
719 | |
720 | child = parent; | |
721 | parent = parent->parent; | |
722 | if (parent) | |
723 | goto up; | |
8277434e | 724 | out: |
eb755805 | 725 | return ret; |
c09595f6 PZ |
726 | } |
727 | ||
029632fb | 728 | int tg_nop(struct task_group *tg, void *data) |
eb755805 | 729 | { |
e2b245f8 | 730 | return 0; |
eb755805 | 731 | } |
18d95a28 PZ |
732 | #endif |
733 | ||
9059393e | 734 | static void set_load_weight(struct task_struct *p, bool update_load) |
45bf76df | 735 | { |
f05998d4 NR |
736 | int prio = p->static_prio - MAX_RT_PRIO; |
737 | struct load_weight *load = &p->se.load; | |
738 | ||
dd41f596 IM |
739 | /* |
740 | * SCHED_IDLE tasks get minimal weight: | |
741 | */ | |
20f9cd2a | 742 | if (idle_policy(p->policy)) { |
c8b28116 | 743 | load->weight = scale_load(WEIGHT_IDLEPRIO); |
f05998d4 | 744 | load->inv_weight = WMULT_IDLEPRIO; |
dd41f596 IM |
745 | return; |
746 | } | |
71f8bd46 | 747 | |
9059393e VG |
748 | /* |
749 | * SCHED_OTHER tasks have to update their load when changing their | |
750 | * weight | |
751 | */ | |
752 | if (update_load && p->sched_class == &fair_sched_class) { | |
753 | reweight_task(p, prio); | |
754 | } else { | |
755 | load->weight = scale_load(sched_prio_to_weight[prio]); | |
756 | load->inv_weight = sched_prio_to_wmult[prio]; | |
757 | } | |
71f8bd46 IM |
758 | } |
759 | ||
1de64443 | 760 | static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) |
2087a1ad | 761 | { |
0a67d1ee PZ |
762 | if (!(flags & ENQUEUE_NOCLOCK)) |
763 | update_rq_clock(rq); | |
764 | ||
1de64443 PZ |
765 | if (!(flags & ENQUEUE_RESTORE)) |
766 | sched_info_queued(rq, p); | |
0a67d1ee | 767 | |
371fd7e7 | 768 | p->sched_class->enqueue_task(rq, p, flags); |
71f8bd46 IM |
769 | } |
770 | ||
1de64443 | 771 | static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) |
71f8bd46 | 772 | { |
0a67d1ee PZ |
773 | if (!(flags & DEQUEUE_NOCLOCK)) |
774 | update_rq_clock(rq); | |
775 | ||
1de64443 PZ |
776 | if (!(flags & DEQUEUE_SAVE)) |
777 | sched_info_dequeued(rq, p); | |
0a67d1ee | 778 | |
371fd7e7 | 779 | p->sched_class->dequeue_task(rq, p, flags); |
71f8bd46 IM |
780 | } |
781 | ||
029632fb | 782 | void activate_task(struct rq *rq, struct task_struct *p, int flags) |
1e3c88bd PZ |
783 | { |
784 | if (task_contributes_to_load(p)) | |
785 | rq->nr_uninterruptible--; | |
786 | ||
371fd7e7 | 787 | enqueue_task(rq, p, flags); |
1e3c88bd PZ |
788 | } |
789 | ||
029632fb | 790 | void deactivate_task(struct rq *rq, struct task_struct *p, int flags) |
1e3c88bd PZ |
791 | { |
792 | if (task_contributes_to_load(p)) | |
793 | rq->nr_uninterruptible++; | |
794 | ||
371fd7e7 | 795 | dequeue_task(rq, p, flags); |
1e3c88bd PZ |
796 | } |
797 | ||
14531189 | 798 | /* |
dd41f596 | 799 | * __normal_prio - return the priority that is based on the static prio |
14531189 | 800 | */ |
14531189 IM |
801 | static inline int __normal_prio(struct task_struct *p) |
802 | { | |
dd41f596 | 803 | return p->static_prio; |
14531189 IM |
804 | } |
805 | ||
b29739f9 IM |
806 | /* |
807 | * Calculate the expected normal priority: i.e. priority | |
808 | * without taking RT-inheritance into account. Might be | |
809 | * boosted by interactivity modifiers. Changes upon fork, | |
810 | * setprio syscalls, and whenever the interactivity | |
811 | * estimator recalculates. | |
812 | */ | |
36c8b586 | 813 | static inline int normal_prio(struct task_struct *p) |
b29739f9 IM |
814 | { |
815 | int prio; | |
816 | ||
aab03e05 DF |
817 | if (task_has_dl_policy(p)) |
818 | prio = MAX_DL_PRIO-1; | |
819 | else if (task_has_rt_policy(p)) | |
b29739f9 IM |
820 | prio = MAX_RT_PRIO-1 - p->rt_priority; |
821 | else | |
822 | prio = __normal_prio(p); | |
823 | return prio; | |
824 | } | |
825 | ||
826 | /* | |
827 | * Calculate the current priority, i.e. the priority | |
828 | * taken into account by the scheduler. This value might | |
829 | * be boosted by RT tasks, or might be boosted by | |
830 | * interactivity modifiers. Will be RT if the task got | |
831 | * RT-boosted. If not then it returns p->normal_prio. | |
832 | */ | |
36c8b586 | 833 | static int effective_prio(struct task_struct *p) |
b29739f9 IM |
834 | { |
835 | p->normal_prio = normal_prio(p); | |
836 | /* | |
837 | * If we are RT tasks or we were boosted to RT priority, | |
838 | * keep the priority unchanged. Otherwise, update priority | |
839 | * to the normal priority: | |
840 | */ | |
841 | if (!rt_prio(p->prio)) | |
842 | return p->normal_prio; | |
843 | return p->prio; | |
844 | } | |
845 | ||
1da177e4 LT |
846 | /** |
847 | * task_curr - is this task currently executing on a CPU? | |
848 | * @p: the task in question. | |
e69f6186 YB |
849 | * |
850 | * Return: 1 if the task is currently executing. 0 otherwise. | |
1da177e4 | 851 | */ |
36c8b586 | 852 | inline int task_curr(const struct task_struct *p) |
1da177e4 LT |
853 | { |
854 | return cpu_curr(task_cpu(p)) == p; | |
855 | } | |
856 | ||
67dfa1b7 | 857 | /* |
4c9a4bc8 PZ |
858 | * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, |
859 | * use the balance_callback list if you want balancing. | |
860 | * | |
861 | * this means any call to check_class_changed() must be followed by a call to | |
862 | * balance_callback(). | |
67dfa1b7 | 863 | */ |
cb469845 SR |
864 | static inline void check_class_changed(struct rq *rq, struct task_struct *p, |
865 | const struct sched_class *prev_class, | |
da7a735e | 866 | int oldprio) |
cb469845 SR |
867 | { |
868 | if (prev_class != p->sched_class) { | |
869 | if (prev_class->switched_from) | |
da7a735e | 870 | prev_class->switched_from(rq, p); |
4c9a4bc8 | 871 | |
da7a735e | 872 | p->sched_class->switched_to(rq, p); |
2d3d891d | 873 | } else if (oldprio != p->prio || dl_task(p)) |
da7a735e | 874 | p->sched_class->prio_changed(rq, p, oldprio); |
cb469845 SR |
875 | } |
876 | ||
029632fb | 877 | void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) |
1e5a7405 PZ |
878 | { |
879 | const struct sched_class *class; | |
880 | ||
881 | if (p->sched_class == rq->curr->sched_class) { | |
882 | rq->curr->sched_class->check_preempt_curr(rq, p, flags); | |
883 | } else { | |
884 | for_each_class(class) { | |
885 | if (class == rq->curr->sched_class) | |
886 | break; | |
887 | if (class == p->sched_class) { | |
8875125e | 888 | resched_curr(rq); |
1e5a7405 PZ |
889 | break; |
890 | } | |
891 | } | |
892 | } | |
893 | ||
894 | /* | |
895 | * A queue event has occurred, and we're going to schedule. In | |
896 | * this case, we can save a useless back to back clock update. | |
897 | */ | |
da0c1e65 | 898 | if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) |
9edfbfed | 899 | rq_clock_skip_update(rq, true); |
1e5a7405 PZ |
900 | } |
901 | ||
1da177e4 | 902 | #ifdef CONFIG_SMP |
5cc389bc PZ |
903 | /* |
904 | * This is how migration works: | |
905 | * | |
906 | * 1) we invoke migration_cpu_stop() on the target CPU using | |
907 | * stop_one_cpu(). | |
908 | * 2) stopper starts to run (implicitly forcing the migrated thread | |
909 | * off the CPU) | |
910 | * 3) it checks whether the migrated task is still in the wrong runqueue. | |
911 | * 4) if it's in the wrong runqueue then the migration thread removes | |
912 | * it and puts it into the right queue. | |
913 | * 5) stopper completes and stop_one_cpu() returns and the migration | |
914 | * is done. | |
915 | */ | |
916 | ||
917 | /* | |
918 | * move_queued_task - move a queued task to new rq. | |
919 | * | |
920 | * Returns (locked) new rq. Old rq's lock is released. | |
921 | */ | |
8a8c69c3 PZ |
922 | static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, |
923 | struct task_struct *p, int new_cpu) | |
5cc389bc | 924 | { |
5cc389bc PZ |
925 | lockdep_assert_held(&rq->lock); |
926 | ||
5cc389bc | 927 | p->on_rq = TASK_ON_RQ_MIGRATING; |
15ff991e | 928 | dequeue_task(rq, p, DEQUEUE_NOCLOCK); |
5cc389bc | 929 | set_task_cpu(p, new_cpu); |
8a8c69c3 | 930 | rq_unlock(rq, rf); |
5cc389bc PZ |
931 | |
932 | rq = cpu_rq(new_cpu); | |
933 | ||
8a8c69c3 | 934 | rq_lock(rq, rf); |
5cc389bc | 935 | BUG_ON(task_cpu(p) != new_cpu); |
5cc389bc | 936 | enqueue_task(rq, p, 0); |
3ea94de1 | 937 | p->on_rq = TASK_ON_RQ_QUEUED; |
5cc389bc PZ |
938 | check_preempt_curr(rq, p, 0); |
939 | ||
940 | return rq; | |
941 | } | |
942 | ||
943 | struct migration_arg { | |
944 | struct task_struct *task; | |
945 | int dest_cpu; | |
946 | }; | |
947 | ||
948 | /* | |
d1ccc66d | 949 | * Move (not current) task off this CPU, onto the destination CPU. We're doing |
5cc389bc PZ |
950 | * this because either it can't run here any more (set_cpus_allowed() |
951 | * away from this CPU, or CPU going down), or because we're | |
952 | * attempting to rebalance this task on exec (sched_exec). | |
953 | * | |
954 | * So we race with normal scheduler movements, but that's OK, as long | |
955 | * as the task is no longer on this CPU. | |
5cc389bc | 956 | */ |
8a8c69c3 PZ |
957 | static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, |
958 | struct task_struct *p, int dest_cpu) | |
5cc389bc | 959 | { |
955dbdf4 TH |
960 | if (p->flags & PF_KTHREAD) { |
961 | if (unlikely(!cpu_online(dest_cpu))) | |
962 | return rq; | |
963 | } else { | |
964 | if (unlikely(!cpu_active(dest_cpu))) | |
965 | return rq; | |
966 | } | |
5cc389bc PZ |
967 | |
968 | /* Affinity changed (again). */ | |
0c98d344 | 969 | if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) |
5e16bbc2 | 970 | return rq; |
5cc389bc | 971 | |
15ff991e | 972 | update_rq_clock(rq); |
8a8c69c3 | 973 | rq = move_queued_task(rq, rf, p, dest_cpu); |
5e16bbc2 PZ |
974 | |
975 | return rq; | |
5cc389bc PZ |
976 | } |
977 | ||
978 | /* | |
979 | * migration_cpu_stop - this will be executed by a highprio stopper thread | |
980 | * and performs thread migration by bumping thread off CPU then | |
981 | * 'pushing' onto another runqueue. | |
982 | */ | |
983 | static int migration_cpu_stop(void *data) | |
984 | { | |
985 | struct migration_arg *arg = data; | |
5e16bbc2 PZ |
986 | struct task_struct *p = arg->task; |
987 | struct rq *rq = this_rq(); | |
8a8c69c3 | 988 | struct rq_flags rf; |
5cc389bc PZ |
989 | |
990 | /* | |
d1ccc66d IM |
991 | * The original target CPU might have gone down and we might |
992 | * be on another CPU but it doesn't matter. | |
5cc389bc PZ |
993 | */ |
994 | local_irq_disable(); | |
995 | /* | |
996 | * We need to explicitly wake pending tasks before running | |
997 | * __migrate_task() such that we will not miss enforcing cpus_allowed | |
998 | * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. | |
999 | */ | |
1000 | sched_ttwu_pending(); | |
5e16bbc2 PZ |
1001 | |
1002 | raw_spin_lock(&p->pi_lock); | |
8a8c69c3 | 1003 | rq_lock(rq, &rf); |
5e16bbc2 PZ |
1004 | /* |
1005 | * If task_rq(p) != rq, it cannot be migrated here, because we're | |
1006 | * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because | |
1007 | * we're holding p->pi_lock. | |
1008 | */ | |
bf89a304 CC |
1009 | if (task_rq(p) == rq) { |
1010 | if (task_on_rq_queued(p)) | |
8a8c69c3 | 1011 | rq = __migrate_task(rq, &rf, p, arg->dest_cpu); |
bf89a304 CC |
1012 | else |
1013 | p->wake_cpu = arg->dest_cpu; | |
1014 | } | |
8a8c69c3 | 1015 | rq_unlock(rq, &rf); |
5e16bbc2 PZ |
1016 | raw_spin_unlock(&p->pi_lock); |
1017 | ||
5cc389bc PZ |
1018 | local_irq_enable(); |
1019 | return 0; | |
1020 | } | |
1021 | ||
c5b28038 PZ |
1022 | /* |
1023 | * sched_class::set_cpus_allowed must do the below, but is not required to | |
1024 | * actually call this function. | |
1025 | */ | |
1026 | void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) | |
5cc389bc | 1027 | { |
5cc389bc PZ |
1028 | cpumask_copy(&p->cpus_allowed, new_mask); |
1029 | p->nr_cpus_allowed = cpumask_weight(new_mask); | |
1030 | } | |
1031 | ||
c5b28038 PZ |
1032 | void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) |
1033 | { | |
6c37067e PZ |
1034 | struct rq *rq = task_rq(p); |
1035 | bool queued, running; | |
1036 | ||
c5b28038 | 1037 | lockdep_assert_held(&p->pi_lock); |
6c37067e PZ |
1038 | |
1039 | queued = task_on_rq_queued(p); | |
1040 | running = task_current(rq, p); | |
1041 | ||
1042 | if (queued) { | |
1043 | /* | |
1044 | * Because __kthread_bind() calls this on blocked tasks without | |
1045 | * holding rq->lock. | |
1046 | */ | |
1047 | lockdep_assert_held(&rq->lock); | |
7a57f32a | 1048 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
6c37067e PZ |
1049 | } |
1050 | if (running) | |
1051 | put_prev_task(rq, p); | |
1052 | ||
c5b28038 | 1053 | p->sched_class->set_cpus_allowed(p, new_mask); |
6c37067e | 1054 | |
6c37067e | 1055 | if (queued) |
7134b3e9 | 1056 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
a399d233 | 1057 | if (running) |
b2bf6c31 | 1058 | set_curr_task(rq, p); |
c5b28038 PZ |
1059 | } |
1060 | ||
5cc389bc PZ |
1061 | /* |
1062 | * Change a given task's CPU affinity. Migrate the thread to a | |
1063 | * proper CPU and schedule it away if the CPU it's executing on | |
1064 | * is removed from the allowed bitmask. | |
1065 | * | |
1066 | * NOTE: the caller must have a valid reference to the task, the | |
1067 | * task must not exit() & deallocate itself prematurely. The | |
1068 | * call is not atomic; no spinlocks may be held. | |
1069 | */ | |
25834c73 PZ |
1070 | static int __set_cpus_allowed_ptr(struct task_struct *p, |
1071 | const struct cpumask *new_mask, bool check) | |
5cc389bc | 1072 | { |
e9d867a6 | 1073 | const struct cpumask *cpu_valid_mask = cpu_active_mask; |
5cc389bc | 1074 | unsigned int dest_cpu; |
eb580751 PZ |
1075 | struct rq_flags rf; |
1076 | struct rq *rq; | |
5cc389bc PZ |
1077 | int ret = 0; |
1078 | ||
eb580751 | 1079 | rq = task_rq_lock(p, &rf); |
a499c3ea | 1080 | update_rq_clock(rq); |
5cc389bc | 1081 | |
e9d867a6 PZI |
1082 | if (p->flags & PF_KTHREAD) { |
1083 | /* | |
1084 | * Kernel threads are allowed on online && !active CPUs | |
1085 | */ | |
1086 | cpu_valid_mask = cpu_online_mask; | |
1087 | } | |
1088 | ||
25834c73 PZ |
1089 | /* |
1090 | * Must re-check here, to close a race against __kthread_bind(), | |
1091 | * sched_setaffinity() is not guaranteed to observe the flag. | |
1092 | */ | |
1093 | if (check && (p->flags & PF_NO_SETAFFINITY)) { | |
1094 | ret = -EINVAL; | |
1095 | goto out; | |
1096 | } | |
1097 | ||
5cc389bc PZ |
1098 | if (cpumask_equal(&p->cpus_allowed, new_mask)) |
1099 | goto out; | |
1100 | ||
e9d867a6 | 1101 | if (!cpumask_intersects(new_mask, cpu_valid_mask)) { |
5cc389bc PZ |
1102 | ret = -EINVAL; |
1103 | goto out; | |
1104 | } | |
1105 | ||
1106 | do_set_cpus_allowed(p, new_mask); | |
1107 | ||
e9d867a6 PZI |
1108 | if (p->flags & PF_KTHREAD) { |
1109 | /* | |
1110 | * For kernel threads that do indeed end up on online && | |
d1ccc66d | 1111 | * !active we want to ensure they are strict per-CPU threads. |
e9d867a6 PZI |
1112 | */ |
1113 | WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && | |
1114 | !cpumask_intersects(new_mask, cpu_active_mask) && | |
1115 | p->nr_cpus_allowed != 1); | |
1116 | } | |
1117 | ||
5cc389bc PZ |
1118 | /* Can the task run on the task's current CPU? If so, we're done */ |
1119 | if (cpumask_test_cpu(task_cpu(p), new_mask)) | |
1120 | goto out; | |
1121 | ||
e9d867a6 | 1122 | dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); |
5cc389bc PZ |
1123 | if (task_running(rq, p) || p->state == TASK_WAKING) { |
1124 | struct migration_arg arg = { p, dest_cpu }; | |
1125 | /* Need help from migration thread: drop lock and wait. */ | |
eb580751 | 1126 | task_rq_unlock(rq, p, &rf); |
5cc389bc PZ |
1127 | stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); |
1128 | tlb_migrate_finish(p->mm); | |
1129 | return 0; | |
cbce1a68 PZ |
1130 | } else if (task_on_rq_queued(p)) { |
1131 | /* | |
1132 | * OK, since we're going to drop the lock immediately | |
1133 | * afterwards anyway. | |
1134 | */ | |
8a8c69c3 | 1135 | rq = move_queued_task(rq, &rf, p, dest_cpu); |
cbce1a68 | 1136 | } |
5cc389bc | 1137 | out: |
eb580751 | 1138 | task_rq_unlock(rq, p, &rf); |
5cc389bc PZ |
1139 | |
1140 | return ret; | |
1141 | } | |
25834c73 PZ |
1142 | |
1143 | int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) | |
1144 | { | |
1145 | return __set_cpus_allowed_ptr(p, new_mask, false); | |
1146 | } | |
5cc389bc PZ |
1147 | EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); |
1148 | ||
dd41f596 | 1149 | void set_task_cpu(struct task_struct *p, unsigned int new_cpu) |
c65cc870 | 1150 | { |
e2912009 PZ |
1151 | #ifdef CONFIG_SCHED_DEBUG |
1152 | /* | |
1153 | * We should never call set_task_cpu() on a blocked task, | |
1154 | * ttwu() will sort out the placement. | |
1155 | */ | |
077614ee | 1156 | WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && |
e2336f6e | 1157 | !p->on_rq); |
0122ec5b | 1158 | |
3ea94de1 JP |
1159 | /* |
1160 | * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, | |
1161 | * because schedstat_wait_{start,end} rebase migrating task's wait_start | |
1162 | * time relying on p->on_rq. | |
1163 | */ | |
1164 | WARN_ON_ONCE(p->state == TASK_RUNNING && | |
1165 | p->sched_class == &fair_sched_class && | |
1166 | (p->on_rq && !task_on_rq_migrating(p))); | |
1167 | ||
0122ec5b | 1168 | #ifdef CONFIG_LOCKDEP |
6c6c54e1 PZ |
1169 | /* |
1170 | * The caller should hold either p->pi_lock or rq->lock, when changing | |
1171 | * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. | |
1172 | * | |
1173 | * sched_move_task() holds both and thus holding either pins the cgroup, | |
8323f26c | 1174 | * see task_group(). |
6c6c54e1 PZ |
1175 | * |
1176 | * Furthermore, all task_rq users should acquire both locks, see | |
1177 | * task_rq_lock(). | |
1178 | */ | |
0122ec5b PZ |
1179 | WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || |
1180 | lockdep_is_held(&task_rq(p)->lock))); | |
1181 | #endif | |
4ff9083b PZ |
1182 | /* |
1183 | * Clearly, migrating tasks to offline CPUs is a fairly daft thing. | |
1184 | */ | |
1185 | WARN_ON_ONCE(!cpu_online(new_cpu)); | |
e2912009 PZ |
1186 | #endif |
1187 | ||
de1d7286 | 1188 | trace_sched_migrate_task(p, new_cpu); |
cbc34ed1 | 1189 | |
0c69774e | 1190 | if (task_cpu(p) != new_cpu) { |
0a74bef8 | 1191 | if (p->sched_class->migrate_task_rq) |
5a4fd036 | 1192 | p->sched_class->migrate_task_rq(p); |
0c69774e | 1193 | p->se.nr_migrations++; |
ff303e66 | 1194 | perf_event_task_migrate(p); |
0c69774e | 1195 | } |
dd41f596 IM |
1196 | |
1197 | __set_task_cpu(p, new_cpu); | |
c65cc870 IM |
1198 | } |
1199 | ||
ac66f547 PZ |
1200 | static void __migrate_swap_task(struct task_struct *p, int cpu) |
1201 | { | |
da0c1e65 | 1202 | if (task_on_rq_queued(p)) { |
ac66f547 | 1203 | struct rq *src_rq, *dst_rq; |
8a8c69c3 | 1204 | struct rq_flags srf, drf; |
ac66f547 PZ |
1205 | |
1206 | src_rq = task_rq(p); | |
1207 | dst_rq = cpu_rq(cpu); | |
1208 | ||
8a8c69c3 PZ |
1209 | rq_pin_lock(src_rq, &srf); |
1210 | rq_pin_lock(dst_rq, &drf); | |
1211 | ||
3ea94de1 | 1212 | p->on_rq = TASK_ON_RQ_MIGRATING; |
ac66f547 PZ |
1213 | deactivate_task(src_rq, p, 0); |
1214 | set_task_cpu(p, cpu); | |
1215 | activate_task(dst_rq, p, 0); | |
3ea94de1 | 1216 | p->on_rq = TASK_ON_RQ_QUEUED; |
ac66f547 | 1217 | check_preempt_curr(dst_rq, p, 0); |
8a8c69c3 PZ |
1218 | |
1219 | rq_unpin_lock(dst_rq, &drf); | |
1220 | rq_unpin_lock(src_rq, &srf); | |
1221 | ||
ac66f547 PZ |
1222 | } else { |
1223 | /* | |
1224 | * Task isn't running anymore; make it appear like we migrated | |
1225 | * it before it went to sleep. This means on wakeup we make the | |
d1ccc66d | 1226 | * previous CPU our target instead of where it really is. |
ac66f547 PZ |
1227 | */ |
1228 | p->wake_cpu = cpu; | |
1229 | } | |
1230 | } | |
1231 | ||
1232 | struct migration_swap_arg { | |
1233 | struct task_struct *src_task, *dst_task; | |
1234 | int src_cpu, dst_cpu; | |
1235 | }; | |
1236 | ||
1237 | static int migrate_swap_stop(void *data) | |
1238 | { | |
1239 | struct migration_swap_arg *arg = data; | |
1240 | struct rq *src_rq, *dst_rq; | |
1241 | int ret = -EAGAIN; | |
1242 | ||
62694cd5 PZ |
1243 | if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) |
1244 | return -EAGAIN; | |
1245 | ||
ac66f547 PZ |
1246 | src_rq = cpu_rq(arg->src_cpu); |
1247 | dst_rq = cpu_rq(arg->dst_cpu); | |
1248 | ||
74602315 PZ |
1249 | double_raw_lock(&arg->src_task->pi_lock, |
1250 | &arg->dst_task->pi_lock); | |
ac66f547 | 1251 | double_rq_lock(src_rq, dst_rq); |
62694cd5 | 1252 | |
ac66f547 PZ |
1253 | if (task_cpu(arg->dst_task) != arg->dst_cpu) |
1254 | goto unlock; | |
1255 | ||
1256 | if (task_cpu(arg->src_task) != arg->src_cpu) | |
1257 | goto unlock; | |
1258 | ||
0c98d344 | 1259 | if (!cpumask_test_cpu(arg->dst_cpu, &arg->src_task->cpus_allowed)) |
ac66f547 PZ |
1260 | goto unlock; |
1261 | ||
0c98d344 | 1262 | if (!cpumask_test_cpu(arg->src_cpu, &arg->dst_task->cpus_allowed)) |
ac66f547 PZ |
1263 | goto unlock; |
1264 | ||
1265 | __migrate_swap_task(arg->src_task, arg->dst_cpu); | |
1266 | __migrate_swap_task(arg->dst_task, arg->src_cpu); | |
1267 | ||
1268 | ret = 0; | |
1269 | ||
1270 | unlock: | |
1271 | double_rq_unlock(src_rq, dst_rq); | |
74602315 PZ |
1272 | raw_spin_unlock(&arg->dst_task->pi_lock); |
1273 | raw_spin_unlock(&arg->src_task->pi_lock); | |
ac66f547 PZ |
1274 | |
1275 | return ret; | |
1276 | } | |
1277 | ||
1278 | /* | |
1279 | * Cross migrate two tasks | |
1280 | */ | |
1281 | int migrate_swap(struct task_struct *cur, struct task_struct *p) | |
1282 | { | |
1283 | struct migration_swap_arg arg; | |
1284 | int ret = -EINVAL; | |
1285 | ||
ac66f547 PZ |
1286 | arg = (struct migration_swap_arg){ |
1287 | .src_task = cur, | |
1288 | .src_cpu = task_cpu(cur), | |
1289 | .dst_task = p, | |
1290 | .dst_cpu = task_cpu(p), | |
1291 | }; | |
1292 | ||
1293 | if (arg.src_cpu == arg.dst_cpu) | |
1294 | goto out; | |
1295 | ||
6acce3ef PZ |
1296 | /* |
1297 | * These three tests are all lockless; this is OK since all of them | |
1298 | * will be re-checked with proper locks held further down the line. | |
1299 | */ | |
ac66f547 PZ |
1300 | if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) |
1301 | goto out; | |
1302 | ||
0c98d344 | 1303 | if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed)) |
ac66f547 PZ |
1304 | goto out; |
1305 | ||
0c98d344 | 1306 | if (!cpumask_test_cpu(arg.src_cpu, &arg.dst_task->cpus_allowed)) |
ac66f547 PZ |
1307 | goto out; |
1308 | ||
286549dc | 1309 | trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); |
ac66f547 PZ |
1310 | ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); |
1311 | ||
1312 | out: | |
ac66f547 PZ |
1313 | return ret; |
1314 | } | |
1315 | ||
1da177e4 LT |
1316 | /* |
1317 | * wait_task_inactive - wait for a thread to unschedule. | |
1318 | * | |
85ba2d86 RM |
1319 | * If @match_state is nonzero, it's the @p->state value just checked and |
1320 | * not expected to change. If it changes, i.e. @p might have woken up, | |
1321 | * then return zero. When we succeed in waiting for @p to be off its CPU, | |
1322 | * we return a positive number (its total switch count). If a second call | |
1323 | * a short while later returns the same number, the caller can be sure that | |
1324 | * @p has remained unscheduled the whole time. | |
1325 | * | |
1da177e4 LT |
1326 | * The caller must ensure that the task *will* unschedule sometime soon, |
1327 | * else this function might spin for a *long* time. This function can't | |
1328 | * be called with interrupts off, or it may introduce deadlock with | |
1329 | * smp_call_function() if an IPI is sent by the same process we are | |
1330 | * waiting to become inactive. | |
1331 | */ | |
85ba2d86 | 1332 | unsigned long wait_task_inactive(struct task_struct *p, long match_state) |
1da177e4 | 1333 | { |
da0c1e65 | 1334 | int running, queued; |
eb580751 | 1335 | struct rq_flags rf; |
85ba2d86 | 1336 | unsigned long ncsw; |
70b97a7f | 1337 | struct rq *rq; |
1da177e4 | 1338 | |
3a5c359a AK |
1339 | for (;;) { |
1340 | /* | |
1341 | * We do the initial early heuristics without holding | |
1342 | * any task-queue locks at all. We'll only try to get | |
1343 | * the runqueue lock when things look like they will | |
1344 | * work out! | |
1345 | */ | |
1346 | rq = task_rq(p); | |
fa490cfd | 1347 | |
3a5c359a AK |
1348 | /* |
1349 | * If the task is actively running on another CPU | |
1350 | * still, just relax and busy-wait without holding | |
1351 | * any locks. | |
1352 | * | |
1353 | * NOTE! Since we don't hold any locks, it's not | |
1354 | * even sure that "rq" stays as the right runqueue! | |
1355 | * But we don't care, since "task_running()" will | |
1356 | * return false if the runqueue has changed and p | |
1357 | * is actually now running somewhere else! | |
1358 | */ | |
85ba2d86 RM |
1359 | while (task_running(rq, p)) { |
1360 | if (match_state && unlikely(p->state != match_state)) | |
1361 | return 0; | |
3a5c359a | 1362 | cpu_relax(); |
85ba2d86 | 1363 | } |
fa490cfd | 1364 | |
3a5c359a AK |
1365 | /* |
1366 | * Ok, time to look more closely! We need the rq | |
1367 | * lock now, to be *sure*. If we're wrong, we'll | |
1368 | * just go back and repeat. | |
1369 | */ | |
eb580751 | 1370 | rq = task_rq_lock(p, &rf); |
27a9da65 | 1371 | trace_sched_wait_task(p); |
3a5c359a | 1372 | running = task_running(rq, p); |
da0c1e65 | 1373 | queued = task_on_rq_queued(p); |
85ba2d86 | 1374 | ncsw = 0; |
f31e11d8 | 1375 | if (!match_state || p->state == match_state) |
93dcf55f | 1376 | ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ |
eb580751 | 1377 | task_rq_unlock(rq, p, &rf); |
fa490cfd | 1378 | |
85ba2d86 RM |
1379 | /* |
1380 | * If it changed from the expected state, bail out now. | |
1381 | */ | |
1382 | if (unlikely(!ncsw)) | |
1383 | break; | |
1384 | ||
3a5c359a AK |
1385 | /* |
1386 | * Was it really running after all now that we | |
1387 | * checked with the proper locks actually held? | |
1388 | * | |
1389 | * Oops. Go back and try again.. | |
1390 | */ | |
1391 | if (unlikely(running)) { | |
1392 | cpu_relax(); | |
1393 | continue; | |
1394 | } | |
fa490cfd | 1395 | |
3a5c359a AK |
1396 | /* |
1397 | * It's not enough that it's not actively running, | |
1398 | * it must be off the runqueue _entirely_, and not | |
1399 | * preempted! | |
1400 | * | |
80dd99b3 | 1401 | * So if it was still runnable (but just not actively |
3a5c359a AK |
1402 | * running right now), it's preempted, and we should |
1403 | * yield - it could be a while. | |
1404 | */ | |
da0c1e65 | 1405 | if (unlikely(queued)) { |
8b0e1953 | 1406 | ktime_t to = NSEC_PER_SEC / HZ; |
8eb90c30 TG |
1407 | |
1408 | set_current_state(TASK_UNINTERRUPTIBLE); | |
1409 | schedule_hrtimeout(&to, HRTIMER_MODE_REL); | |
3a5c359a AK |
1410 | continue; |
1411 | } | |
fa490cfd | 1412 | |
3a5c359a AK |
1413 | /* |
1414 | * Ahh, all good. It wasn't running, and it wasn't | |
1415 | * runnable, which means that it will never become | |
1416 | * running in the future either. We're all done! | |
1417 | */ | |
1418 | break; | |
1419 | } | |
85ba2d86 RM |
1420 | |
1421 | return ncsw; | |
1da177e4 LT |
1422 | } |
1423 | ||
1424 | /*** | |
1425 | * kick_process - kick a running thread to enter/exit the kernel | |
1426 | * @p: the to-be-kicked thread | |
1427 | * | |
1428 | * Cause a process which is running on another CPU to enter | |
1429 | * kernel-mode, without any delay. (to get signals handled.) | |
1430 | * | |
25985edc | 1431 | * NOTE: this function doesn't have to take the runqueue lock, |
1da177e4 LT |
1432 | * because all it wants to ensure is that the remote task enters |
1433 | * the kernel. If the IPI races and the task has been migrated | |
1434 | * to another CPU then no harm is done and the purpose has been | |
1435 | * achieved as well. | |
1436 | */ | |
36c8b586 | 1437 | void kick_process(struct task_struct *p) |
1da177e4 LT |
1438 | { |
1439 | int cpu; | |
1440 | ||
1441 | preempt_disable(); | |
1442 | cpu = task_cpu(p); | |
1443 | if ((cpu != smp_processor_id()) && task_curr(p)) | |
1444 | smp_send_reschedule(cpu); | |
1445 | preempt_enable(); | |
1446 | } | |
b43e3521 | 1447 | EXPORT_SYMBOL_GPL(kick_process); |
1da177e4 | 1448 | |
30da688e | 1449 | /* |
013fdb80 | 1450 | * ->cpus_allowed is protected by both rq->lock and p->pi_lock |
e9d867a6 PZI |
1451 | * |
1452 | * A few notes on cpu_active vs cpu_online: | |
1453 | * | |
1454 | * - cpu_active must be a subset of cpu_online | |
1455 | * | |
1456 | * - on cpu-up we allow per-cpu kthreads on the online && !active cpu, | |
1457 | * see __set_cpus_allowed_ptr(). At this point the newly online | |
d1ccc66d | 1458 | * CPU isn't yet part of the sched domains, and balancing will not |
e9d867a6 PZI |
1459 | * see it. |
1460 | * | |
d1ccc66d | 1461 | * - on CPU-down we clear cpu_active() to mask the sched domains and |
e9d867a6 | 1462 | * avoid the load balancer to place new tasks on the to be removed |
d1ccc66d | 1463 | * CPU. Existing tasks will remain running there and will be taken |
e9d867a6 PZI |
1464 | * off. |
1465 | * | |
1466 | * This means that fallback selection must not select !active CPUs. | |
1467 | * And can assume that any active CPU must be online. Conversely | |
1468 | * select_task_rq() below may allow selection of !active CPUs in order | |
1469 | * to satisfy the above rules. | |
30da688e | 1470 | */ |
5da9a0fb PZ |
1471 | static int select_fallback_rq(int cpu, struct task_struct *p) |
1472 | { | |
aa00d89c TC |
1473 | int nid = cpu_to_node(cpu); |
1474 | const struct cpumask *nodemask = NULL; | |
2baab4e9 PZ |
1475 | enum { cpuset, possible, fail } state = cpuset; |
1476 | int dest_cpu; | |
5da9a0fb | 1477 | |
aa00d89c | 1478 | /* |
d1ccc66d IM |
1479 | * If the node that the CPU is on has been offlined, cpu_to_node() |
1480 | * will return -1. There is no CPU on the node, and we should | |
1481 | * select the CPU on the other node. | |
aa00d89c TC |
1482 | */ |
1483 | if (nid != -1) { | |
1484 | nodemask = cpumask_of_node(nid); | |
1485 | ||
1486 | /* Look for allowed, online CPU in same node. */ | |
1487 | for_each_cpu(dest_cpu, nodemask) { | |
aa00d89c TC |
1488 | if (!cpu_active(dest_cpu)) |
1489 | continue; | |
0c98d344 | 1490 | if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) |
aa00d89c TC |
1491 | return dest_cpu; |
1492 | } | |
2baab4e9 | 1493 | } |
5da9a0fb | 1494 | |
2baab4e9 PZ |
1495 | for (;;) { |
1496 | /* Any allowed, online CPU? */ | |
0c98d344 | 1497 | for_each_cpu(dest_cpu, &p->cpus_allowed) { |
feb245e3 TH |
1498 | if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) |
1499 | continue; | |
1500 | if (!cpu_online(dest_cpu)) | |
2baab4e9 PZ |
1501 | continue; |
1502 | goto out; | |
1503 | } | |
5da9a0fb | 1504 | |
e73e85f0 | 1505 | /* No more Mr. Nice Guy. */ |
2baab4e9 PZ |
1506 | switch (state) { |
1507 | case cpuset: | |
e73e85f0 ON |
1508 | if (IS_ENABLED(CONFIG_CPUSETS)) { |
1509 | cpuset_cpus_allowed_fallback(p); | |
1510 | state = possible; | |
1511 | break; | |
1512 | } | |
d1ccc66d | 1513 | /* Fall-through */ |
2baab4e9 PZ |
1514 | case possible: |
1515 | do_set_cpus_allowed(p, cpu_possible_mask); | |
1516 | state = fail; | |
1517 | break; | |
1518 | ||
1519 | case fail: | |
1520 | BUG(); | |
1521 | break; | |
1522 | } | |
1523 | } | |
1524 | ||
1525 | out: | |
1526 | if (state != cpuset) { | |
1527 | /* | |
1528 | * Don't tell them about moving exiting tasks or | |
1529 | * kernel threads (both mm NULL), since they never | |
1530 | * leave kernel. | |
1531 | */ | |
1532 | if (p->mm && printk_ratelimit()) { | |
aac74dc4 | 1533 | printk_deferred("process %d (%s) no longer affine to cpu%d\n", |
2baab4e9 PZ |
1534 | task_pid_nr(p), p->comm, cpu); |
1535 | } | |
5da9a0fb PZ |
1536 | } |
1537 | ||
1538 | return dest_cpu; | |
1539 | } | |
1540 | ||
e2912009 | 1541 | /* |
013fdb80 | 1542 | * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. |
e2912009 | 1543 | */ |
970b13ba | 1544 | static inline |
ac66f547 | 1545 | int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) |
970b13ba | 1546 | { |
cbce1a68 PZ |
1547 | lockdep_assert_held(&p->pi_lock); |
1548 | ||
4b53a341 | 1549 | if (p->nr_cpus_allowed > 1) |
6c1d9410 | 1550 | cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); |
e9d867a6 | 1551 | else |
0c98d344 | 1552 | cpu = cpumask_any(&p->cpus_allowed); |
e2912009 PZ |
1553 | |
1554 | /* | |
1555 | * In order not to call set_task_cpu() on a blocking task we need | |
1556 | * to rely on ttwu() to place the task on a valid ->cpus_allowed | |
d1ccc66d | 1557 | * CPU. |
e2912009 PZ |
1558 | * |
1559 | * Since this is common to all placement strategies, this lives here. | |
1560 | * | |
1561 | * [ this allows ->select_task() to simply return task_cpu(p) and | |
1562 | * not worry about this generic constraint ] | |
1563 | */ | |
0c98d344 | 1564 | if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) || |
70f11205 | 1565 | !cpu_online(cpu))) |
5da9a0fb | 1566 | cpu = select_fallback_rq(task_cpu(p), p); |
e2912009 PZ |
1567 | |
1568 | return cpu; | |
970b13ba | 1569 | } |
09a40af5 MG |
1570 | |
1571 | static void update_avg(u64 *avg, u64 sample) | |
1572 | { | |
1573 | s64 diff = sample - *avg; | |
1574 | *avg += diff >> 3; | |
1575 | } | |
25834c73 | 1576 | |
f5832c19 NP |
1577 | void sched_set_stop_task(int cpu, struct task_struct *stop) |
1578 | { | |
1579 | struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; | |
1580 | struct task_struct *old_stop = cpu_rq(cpu)->stop; | |
1581 | ||
1582 | if (stop) { | |
1583 | /* | |
1584 | * Make it appear like a SCHED_FIFO task, its something | |
1585 | * userspace knows about and won't get confused about. | |
1586 | * | |
1587 | * Also, it will make PI more or less work without too | |
1588 | * much confusion -- but then, stop work should not | |
1589 | * rely on PI working anyway. | |
1590 | */ | |
1591 | sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); | |
1592 | ||
1593 | stop->sched_class = &stop_sched_class; | |
1594 | } | |
1595 | ||
1596 | cpu_rq(cpu)->stop = stop; | |
1597 | ||
1598 | if (old_stop) { | |
1599 | /* | |
1600 | * Reset it back to a normal scheduling class so that | |
1601 | * it can die in pieces. | |
1602 | */ | |
1603 | old_stop->sched_class = &rt_sched_class; | |
1604 | } | |
1605 | } | |
1606 | ||
25834c73 PZ |
1607 | #else |
1608 | ||
1609 | static inline int __set_cpus_allowed_ptr(struct task_struct *p, | |
1610 | const struct cpumask *new_mask, bool check) | |
1611 | { | |
1612 | return set_cpus_allowed_ptr(p, new_mask); | |
1613 | } | |
1614 | ||
5cc389bc | 1615 | #endif /* CONFIG_SMP */ |
970b13ba | 1616 | |
d7c01d27 | 1617 | static void |
b84cb5df | 1618 | ttwu_stat(struct task_struct *p, int cpu, int wake_flags) |
9ed3811a | 1619 | { |
4fa8d299 | 1620 | struct rq *rq; |
b84cb5df | 1621 | |
4fa8d299 JP |
1622 | if (!schedstat_enabled()) |
1623 | return; | |
1624 | ||
1625 | rq = this_rq(); | |
d7c01d27 | 1626 | |
4fa8d299 JP |
1627 | #ifdef CONFIG_SMP |
1628 | if (cpu == rq->cpu) { | |
ae92882e JP |
1629 | schedstat_inc(rq->ttwu_local); |
1630 | schedstat_inc(p->se.statistics.nr_wakeups_local); | |
d7c01d27 PZ |
1631 | } else { |
1632 | struct sched_domain *sd; | |
1633 | ||
ae92882e | 1634 | schedstat_inc(p->se.statistics.nr_wakeups_remote); |
057f3fad | 1635 | rcu_read_lock(); |
4fa8d299 | 1636 | for_each_domain(rq->cpu, sd) { |
d7c01d27 | 1637 | if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { |
ae92882e | 1638 | schedstat_inc(sd->ttwu_wake_remote); |
d7c01d27 PZ |
1639 | break; |
1640 | } | |
1641 | } | |
057f3fad | 1642 | rcu_read_unlock(); |
d7c01d27 | 1643 | } |
f339b9dc PZ |
1644 | |
1645 | if (wake_flags & WF_MIGRATED) | |
ae92882e | 1646 | schedstat_inc(p->se.statistics.nr_wakeups_migrate); |
d7c01d27 PZ |
1647 | #endif /* CONFIG_SMP */ |
1648 | ||
ae92882e JP |
1649 | schedstat_inc(rq->ttwu_count); |
1650 | schedstat_inc(p->se.statistics.nr_wakeups); | |
d7c01d27 PZ |
1651 | |
1652 | if (wake_flags & WF_SYNC) | |
ae92882e | 1653 | schedstat_inc(p->se.statistics.nr_wakeups_sync); |
d7c01d27 PZ |
1654 | } |
1655 | ||
1de64443 | 1656 | static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) |
d7c01d27 | 1657 | { |
9ed3811a | 1658 | activate_task(rq, p, en_flags); |
da0c1e65 | 1659 | p->on_rq = TASK_ON_RQ_QUEUED; |
c2f7115e | 1660 | |
d1ccc66d | 1661 | /* If a worker is waking up, notify the workqueue: */ |
c2f7115e PZ |
1662 | if (p->flags & PF_WQ_WORKER) |
1663 | wq_worker_waking_up(p, cpu_of(rq)); | |
9ed3811a TH |
1664 | } |
1665 | ||
23f41eeb PZ |
1666 | /* |
1667 | * Mark the task runnable and perform wakeup-preemption. | |
1668 | */ | |
e7904a28 | 1669 | static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, |
d8ac8971 | 1670 | struct rq_flags *rf) |
9ed3811a | 1671 | { |
9ed3811a | 1672 | check_preempt_curr(rq, p, wake_flags); |
9ed3811a | 1673 | p->state = TASK_RUNNING; |
fbd705a0 PZ |
1674 | trace_sched_wakeup(p); |
1675 | ||
9ed3811a | 1676 | #ifdef CONFIG_SMP |
4c9a4bc8 PZ |
1677 | if (p->sched_class->task_woken) { |
1678 | /* | |
cbce1a68 PZ |
1679 | * Our task @p is fully woken up and running; so its safe to |
1680 | * drop the rq->lock, hereafter rq is only used for statistics. | |
4c9a4bc8 | 1681 | */ |
d8ac8971 | 1682 | rq_unpin_lock(rq, rf); |
9ed3811a | 1683 | p->sched_class->task_woken(rq, p); |
d8ac8971 | 1684 | rq_repin_lock(rq, rf); |
4c9a4bc8 | 1685 | } |
9ed3811a | 1686 | |
e69c6341 | 1687 | if (rq->idle_stamp) { |
78becc27 | 1688 | u64 delta = rq_clock(rq) - rq->idle_stamp; |
9bd721c5 | 1689 | u64 max = 2*rq->max_idle_balance_cost; |
9ed3811a | 1690 | |
abfafa54 JL |
1691 | update_avg(&rq->avg_idle, delta); |
1692 | ||
1693 | if (rq->avg_idle > max) | |
9ed3811a | 1694 | rq->avg_idle = max; |
abfafa54 | 1695 | |
9ed3811a TH |
1696 | rq->idle_stamp = 0; |
1697 | } | |
1698 | #endif | |
1699 | } | |
1700 | ||
c05fbafb | 1701 | static void |
e7904a28 | 1702 | ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, |
d8ac8971 | 1703 | struct rq_flags *rf) |
c05fbafb | 1704 | { |
77558e4d | 1705 | int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK; |
b5179ac7 | 1706 | |
cbce1a68 PZ |
1707 | lockdep_assert_held(&rq->lock); |
1708 | ||
c05fbafb PZ |
1709 | #ifdef CONFIG_SMP |
1710 | if (p->sched_contributes_to_load) | |
1711 | rq->nr_uninterruptible--; | |
b5179ac7 | 1712 | |
b5179ac7 | 1713 | if (wake_flags & WF_MIGRATED) |
59efa0ba | 1714 | en_flags |= ENQUEUE_MIGRATED; |
c05fbafb PZ |
1715 | #endif |
1716 | ||
b5179ac7 | 1717 | ttwu_activate(rq, p, en_flags); |
d8ac8971 | 1718 | ttwu_do_wakeup(rq, p, wake_flags, rf); |
c05fbafb PZ |
1719 | } |
1720 | ||
1721 | /* | |
1722 | * Called in case the task @p isn't fully descheduled from its runqueue, | |
1723 | * in this case we must do a remote wakeup. Its a 'light' wakeup though, | |
1724 | * since all we need to do is flip p->state to TASK_RUNNING, since | |
1725 | * the task is still ->on_rq. | |
1726 | */ | |
1727 | static int ttwu_remote(struct task_struct *p, int wake_flags) | |
1728 | { | |
eb580751 | 1729 | struct rq_flags rf; |
c05fbafb PZ |
1730 | struct rq *rq; |
1731 | int ret = 0; | |
1732 | ||
eb580751 | 1733 | rq = __task_rq_lock(p, &rf); |
da0c1e65 | 1734 | if (task_on_rq_queued(p)) { |
1ad4ec0d FW |
1735 | /* check_preempt_curr() may use rq clock */ |
1736 | update_rq_clock(rq); | |
d8ac8971 | 1737 | ttwu_do_wakeup(rq, p, wake_flags, &rf); |
c05fbafb PZ |
1738 | ret = 1; |
1739 | } | |
eb580751 | 1740 | __task_rq_unlock(rq, &rf); |
c05fbafb PZ |
1741 | |
1742 | return ret; | |
1743 | } | |
1744 | ||
317f3941 | 1745 | #ifdef CONFIG_SMP |
e3baac47 | 1746 | void sched_ttwu_pending(void) |
317f3941 PZ |
1747 | { |
1748 | struct rq *rq = this_rq(); | |
fa14ff4a | 1749 | struct llist_node *llist = llist_del_all(&rq->wake_list); |
73215849 | 1750 | struct task_struct *p, *t; |
d8ac8971 | 1751 | struct rq_flags rf; |
317f3941 | 1752 | |
e3baac47 PZ |
1753 | if (!llist) |
1754 | return; | |
1755 | ||
8a8c69c3 | 1756 | rq_lock_irqsave(rq, &rf); |
77558e4d | 1757 | update_rq_clock(rq); |
317f3941 | 1758 | |
73215849 BP |
1759 | llist_for_each_entry_safe(p, t, llist, wake_entry) |
1760 | ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); | |
317f3941 | 1761 | |
8a8c69c3 | 1762 | rq_unlock_irqrestore(rq, &rf); |
317f3941 PZ |
1763 | } |
1764 | ||
1765 | void scheduler_ipi(void) | |
1766 | { | |
f27dde8d PZ |
1767 | /* |
1768 | * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting | |
1769 | * TIF_NEED_RESCHED remotely (for the first time) will also send | |
1770 | * this IPI. | |
1771 | */ | |
8cb75e0c | 1772 | preempt_fold_need_resched(); |
f27dde8d | 1773 | |
fd2ac4f4 | 1774 | if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) |
c5d753a5 PZ |
1775 | return; |
1776 | ||
1777 | /* | |
1778 | * Not all reschedule IPI handlers call irq_enter/irq_exit, since | |
1779 | * traditionally all their work was done from the interrupt return | |
1780 | * path. Now that we actually do some work, we need to make sure | |
1781 | * we do call them. | |
1782 | * | |
1783 | * Some archs already do call them, luckily irq_enter/exit nest | |
1784 | * properly. | |
1785 | * | |
1786 | * Arguably we should visit all archs and update all handlers, | |
1787 | * however a fair share of IPIs are still resched only so this would | |
1788 | * somewhat pessimize the simple resched case. | |
1789 | */ | |
1790 | irq_enter(); | |
fa14ff4a | 1791 | sched_ttwu_pending(); |
ca38062e SS |
1792 | |
1793 | /* | |
1794 | * Check if someone kicked us for doing the nohz idle load balance. | |
1795 | */ | |
873b4c65 | 1796 | if (unlikely(got_nohz_idle_kick())) { |
6eb57e0d | 1797 | this_rq()->idle_balance = 1; |
ca38062e | 1798 | raise_softirq_irqoff(SCHED_SOFTIRQ); |
6eb57e0d | 1799 | } |
c5d753a5 | 1800 | irq_exit(); |
317f3941 PZ |
1801 | } |
1802 | ||
b7e7ade3 | 1803 | static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) |
317f3941 | 1804 | { |
e3baac47 PZ |
1805 | struct rq *rq = cpu_rq(cpu); |
1806 | ||
b7e7ade3 PZ |
1807 | p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); |
1808 | ||
e3baac47 PZ |
1809 | if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { |
1810 | if (!set_nr_if_polling(rq->idle)) | |
1811 | smp_send_reschedule(cpu); | |
1812 | else | |
1813 | trace_sched_wake_idle_without_ipi(cpu); | |
1814 | } | |
317f3941 | 1815 | } |
d6aa8f85 | 1816 | |
f6be8af1 CL |
1817 | void wake_up_if_idle(int cpu) |
1818 | { | |
1819 | struct rq *rq = cpu_rq(cpu); | |
8a8c69c3 | 1820 | struct rq_flags rf; |
f6be8af1 | 1821 | |
fd7de1e8 AL |
1822 | rcu_read_lock(); |
1823 | ||
1824 | if (!is_idle_task(rcu_dereference(rq->curr))) | |
1825 | goto out; | |
f6be8af1 CL |
1826 | |
1827 | if (set_nr_if_polling(rq->idle)) { | |
1828 | trace_sched_wake_idle_without_ipi(cpu); | |
1829 | } else { | |
8a8c69c3 | 1830 | rq_lock_irqsave(rq, &rf); |
f6be8af1 CL |
1831 | if (is_idle_task(rq->curr)) |
1832 | smp_send_reschedule(cpu); | |
d1ccc66d | 1833 | /* Else CPU is not idle, do nothing here: */ |
8a8c69c3 | 1834 | rq_unlock_irqrestore(rq, &rf); |
f6be8af1 | 1835 | } |
fd7de1e8 AL |
1836 | |
1837 | out: | |
1838 | rcu_read_unlock(); | |
f6be8af1 CL |
1839 | } |
1840 | ||
39be3501 | 1841 | bool cpus_share_cache(int this_cpu, int that_cpu) |
518cd623 PZ |
1842 | { |
1843 | return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); | |
1844 | } | |
d6aa8f85 | 1845 | #endif /* CONFIG_SMP */ |
317f3941 | 1846 | |
b5179ac7 | 1847 | static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) |
c05fbafb PZ |
1848 | { |
1849 | struct rq *rq = cpu_rq(cpu); | |
d8ac8971 | 1850 | struct rq_flags rf; |
c05fbafb | 1851 | |
17d9f311 | 1852 | #if defined(CONFIG_SMP) |
39be3501 | 1853 | if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { |
d1ccc66d | 1854 | sched_clock_cpu(cpu); /* Sync clocks across CPUs */ |
b7e7ade3 | 1855 | ttwu_queue_remote(p, cpu, wake_flags); |
317f3941 PZ |
1856 | return; |
1857 | } | |
1858 | #endif | |
1859 | ||
8a8c69c3 | 1860 | rq_lock(rq, &rf); |
77558e4d | 1861 | update_rq_clock(rq); |
d8ac8971 | 1862 | ttwu_do_activate(rq, p, wake_flags, &rf); |
8a8c69c3 | 1863 | rq_unlock(rq, &rf); |
9ed3811a TH |
1864 | } |
1865 | ||
8643cda5 PZ |
1866 | /* |
1867 | * Notes on Program-Order guarantees on SMP systems. | |
1868 | * | |
1869 | * MIGRATION | |
1870 | * | |
1871 | * The basic program-order guarantee on SMP systems is that when a task [t] | |
d1ccc66d IM |
1872 | * migrates, all its activity on its old CPU [c0] happens-before any subsequent |
1873 | * execution on its new CPU [c1]. | |
8643cda5 PZ |
1874 | * |
1875 | * For migration (of runnable tasks) this is provided by the following means: | |
1876 | * | |
1877 | * A) UNLOCK of the rq(c0)->lock scheduling out task t | |
1878 | * B) migration for t is required to synchronize *both* rq(c0)->lock and | |
1879 | * rq(c1)->lock (if not at the same time, then in that order). | |
1880 | * C) LOCK of the rq(c1)->lock scheduling in task | |
1881 | * | |
1882 | * Transitivity guarantees that B happens after A and C after B. | |
1883 | * Note: we only require RCpc transitivity. | |
d1ccc66d | 1884 | * Note: the CPU doing B need not be c0 or c1 |
8643cda5 PZ |
1885 | * |
1886 | * Example: | |
1887 | * | |
1888 | * CPU0 CPU1 CPU2 | |
1889 | * | |
1890 | * LOCK rq(0)->lock | |
1891 | * sched-out X | |
1892 | * sched-in Y | |
1893 | * UNLOCK rq(0)->lock | |
1894 | * | |
1895 | * LOCK rq(0)->lock // orders against CPU0 | |
1896 | * dequeue X | |
1897 | * UNLOCK rq(0)->lock | |
1898 | * | |
1899 | * LOCK rq(1)->lock | |
1900 | * enqueue X | |
1901 | * UNLOCK rq(1)->lock | |
1902 | * | |
1903 | * LOCK rq(1)->lock // orders against CPU2 | |
1904 | * sched-out Z | |
1905 | * sched-in X | |
1906 | * UNLOCK rq(1)->lock | |
1907 | * | |
1908 | * | |
1909 | * BLOCKING -- aka. SLEEP + WAKEUP | |
1910 | * | |
1911 | * For blocking we (obviously) need to provide the same guarantee as for | |
1912 | * migration. However the means are completely different as there is no lock | |
1913 | * chain to provide order. Instead we do: | |
1914 | * | |
1915 | * 1) smp_store_release(X->on_cpu, 0) | |
1f03e8d2 | 1916 | * 2) smp_cond_load_acquire(!X->on_cpu) |
8643cda5 PZ |
1917 | * |
1918 | * Example: | |
1919 | * | |
1920 | * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) | |
1921 | * | |
1922 | * LOCK rq(0)->lock LOCK X->pi_lock | |
1923 | * dequeue X | |
1924 | * sched-out X | |
1925 | * smp_store_release(X->on_cpu, 0); | |
1926 | * | |
1f03e8d2 | 1927 | * smp_cond_load_acquire(&X->on_cpu, !VAL); |
8643cda5 PZ |
1928 | * X->state = WAKING |
1929 | * set_task_cpu(X,2) | |
1930 | * | |
1931 | * LOCK rq(2)->lock | |
1932 | * enqueue X | |
1933 | * X->state = RUNNING | |
1934 | * UNLOCK rq(2)->lock | |
1935 | * | |
1936 | * LOCK rq(2)->lock // orders against CPU1 | |
1937 | * sched-out Z | |
1938 | * sched-in X | |
1939 | * UNLOCK rq(2)->lock | |
1940 | * | |
1941 | * UNLOCK X->pi_lock | |
1942 | * UNLOCK rq(0)->lock | |
1943 | * | |
1944 | * | |
1945 | * However; for wakeups there is a second guarantee we must provide, namely we | |
1946 | * must observe the state that lead to our wakeup. That is, not only must our | |
1947 | * task observe its own prior state, it must also observe the stores prior to | |
1948 | * its wakeup. | |
1949 | * | |
1950 | * This means that any means of doing remote wakeups must order the CPU doing | |
1951 | * the wakeup against the CPU the task is going to end up running on. This, | |
1952 | * however, is already required for the regular Program-Order guarantee above, | |
1f03e8d2 | 1953 | * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). |
8643cda5 PZ |
1954 | * |
1955 | */ | |
1956 | ||
9ed3811a | 1957 | /** |
1da177e4 | 1958 | * try_to_wake_up - wake up a thread |
9ed3811a | 1959 | * @p: the thread to be awakened |
1da177e4 | 1960 | * @state: the mask of task states that can be woken |
9ed3811a | 1961 | * @wake_flags: wake modifier flags (WF_*) |
1da177e4 | 1962 | * |
a2250238 | 1963 | * If (@state & @p->state) @p->state = TASK_RUNNING. |
1da177e4 | 1964 | * |
a2250238 PZ |
1965 | * If the task was not queued/runnable, also place it back on a runqueue. |
1966 | * | |
1967 | * Atomic against schedule() which would dequeue a task, also see | |
1968 | * set_current_state(). | |
1969 | * | |
1970 | * Return: %true if @p->state changes (an actual wakeup was done), | |
1971 | * %false otherwise. | |
1da177e4 | 1972 | */ |
e4a52bcb PZ |
1973 | static int |
1974 | try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) | |
1da177e4 | 1975 | { |
1da177e4 | 1976 | unsigned long flags; |
c05fbafb | 1977 | int cpu, success = 0; |
2398f2c6 | 1978 | |
e0acd0a6 ON |
1979 | /* |
1980 | * If we are going to wake up a thread waiting for CONDITION we | |
1981 | * need to ensure that CONDITION=1 done by the caller can not be | |
1982 | * reordered with p->state check below. This pairs with mb() in | |
1983 | * set_current_state() the waiting thread does. | |
1984 | */ | |
013fdb80 | 1985 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
d89e588c | 1986 | smp_mb__after_spinlock(); |
e9c84311 | 1987 | if (!(p->state & state)) |
1da177e4 LT |
1988 | goto out; |
1989 | ||
fbd705a0 PZ |
1990 | trace_sched_waking(p); |
1991 | ||
d1ccc66d IM |
1992 | /* We're going to change ->state: */ |
1993 | success = 1; | |
1da177e4 | 1994 | cpu = task_cpu(p); |
1da177e4 | 1995 | |
135e8c92 BS |
1996 | /* |
1997 | * Ensure we load p->on_rq _after_ p->state, otherwise it would | |
1998 | * be possible to, falsely, observe p->on_rq == 0 and get stuck | |
1999 | * in smp_cond_load_acquire() below. | |
2000 | * | |
2001 | * sched_ttwu_pending() try_to_wake_up() | |
2002 | * [S] p->on_rq = 1; [L] P->state | |
2003 | * UNLOCK rq->lock -----. | |
2004 | * \ | |
2005 | * +--- RMB | |
2006 | * schedule() / | |
2007 | * LOCK rq->lock -----' | |
2008 | * UNLOCK rq->lock | |
2009 | * | |
2010 | * [task p] | |
2011 | * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq | |
2012 | * | |
2013 | * Pairs with the UNLOCK+LOCK on rq->lock from the | |
2014 | * last wakeup of our task and the schedule that got our task | |
2015 | * current. | |
2016 | */ | |
2017 | smp_rmb(); | |
c05fbafb PZ |
2018 | if (p->on_rq && ttwu_remote(p, wake_flags)) |
2019 | goto stat; | |
1da177e4 | 2020 | |
1da177e4 | 2021 | #ifdef CONFIG_SMP |
ecf7d01c PZ |
2022 | /* |
2023 | * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be | |
2024 | * possible to, falsely, observe p->on_cpu == 0. | |
2025 | * | |
2026 | * One must be running (->on_cpu == 1) in order to remove oneself | |
2027 | * from the runqueue. | |
2028 | * | |
2029 | * [S] ->on_cpu = 1; [L] ->on_rq | |
2030 | * UNLOCK rq->lock | |
2031 | * RMB | |
2032 | * LOCK rq->lock | |
2033 | * [S] ->on_rq = 0; [L] ->on_cpu | |
2034 | * | |
2035 | * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock | |
2036 | * from the consecutive calls to schedule(); the first switching to our | |
2037 | * task, the second putting it to sleep. | |
2038 | */ | |
2039 | smp_rmb(); | |
2040 | ||
e9c84311 | 2041 | /* |
d1ccc66d | 2042 | * If the owning (remote) CPU is still in the middle of schedule() with |
c05fbafb | 2043 | * this task as prev, wait until its done referencing the task. |
b75a2253 PZ |
2044 | * |
2045 | * Pairs with the smp_store_release() in finish_lock_switch(). | |
2046 | * | |
2047 | * This ensures that tasks getting woken will be fully ordered against | |
2048 | * their previous state and preserve Program Order. | |
0970d299 | 2049 | */ |
1f03e8d2 | 2050 | smp_cond_load_acquire(&p->on_cpu, !VAL); |
1da177e4 | 2051 | |
a8e4f2ea | 2052 | p->sched_contributes_to_load = !!task_contributes_to_load(p); |
e9c84311 | 2053 | p->state = TASK_WAKING; |
e7693a36 | 2054 | |
e33a9bba TH |
2055 | if (p->in_iowait) { |
2056 | delayacct_blkio_end(); | |
2057 | atomic_dec(&task_rq(p)->nr_iowait); | |
2058 | } | |
2059 | ||
ac66f547 | 2060 | cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); |
f339b9dc PZ |
2061 | if (task_cpu(p) != cpu) { |
2062 | wake_flags |= WF_MIGRATED; | |
e4a52bcb | 2063 | set_task_cpu(p, cpu); |
f339b9dc | 2064 | } |
e33a9bba TH |
2065 | |
2066 | #else /* CONFIG_SMP */ | |
2067 | ||
2068 | if (p->in_iowait) { | |
2069 | delayacct_blkio_end(); | |
2070 | atomic_dec(&task_rq(p)->nr_iowait); | |
2071 | } | |
2072 | ||
1da177e4 | 2073 | #endif /* CONFIG_SMP */ |
1da177e4 | 2074 | |
b5179ac7 | 2075 | ttwu_queue(p, cpu, wake_flags); |
c05fbafb | 2076 | stat: |
4fa8d299 | 2077 | ttwu_stat(p, cpu, wake_flags); |
1da177e4 | 2078 | out: |
013fdb80 | 2079 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 LT |
2080 | |
2081 | return success; | |
2082 | } | |
2083 | ||
21aa9af0 TH |
2084 | /** |
2085 | * try_to_wake_up_local - try to wake up a local task with rq lock held | |
2086 | * @p: the thread to be awakened | |
bf50f0e8 | 2087 | * @rf: request-queue flags for pinning |
21aa9af0 | 2088 | * |
2acca55e | 2089 | * Put @p on the run-queue if it's not already there. The caller must |
21aa9af0 | 2090 | * ensure that this_rq() is locked, @p is bound to this_rq() and not |
2acca55e | 2091 | * the current task. |
21aa9af0 | 2092 | */ |
d8ac8971 | 2093 | static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf) |
21aa9af0 TH |
2094 | { |
2095 | struct rq *rq = task_rq(p); | |
21aa9af0 | 2096 | |
383efcd0 TH |
2097 | if (WARN_ON_ONCE(rq != this_rq()) || |
2098 | WARN_ON_ONCE(p == current)) | |
2099 | return; | |
2100 | ||
21aa9af0 TH |
2101 | lockdep_assert_held(&rq->lock); |
2102 | ||
2acca55e | 2103 | if (!raw_spin_trylock(&p->pi_lock)) { |
cbce1a68 PZ |
2104 | /* |
2105 | * This is OK, because current is on_cpu, which avoids it being | |
2106 | * picked for load-balance and preemption/IRQs are still | |
2107 | * disabled avoiding further scheduler activity on it and we've | |
2108 | * not yet picked a replacement task. | |
2109 | */ | |
8a8c69c3 | 2110 | rq_unlock(rq, rf); |
2acca55e | 2111 | raw_spin_lock(&p->pi_lock); |
8a8c69c3 | 2112 | rq_relock(rq, rf); |
2acca55e PZ |
2113 | } |
2114 | ||
21aa9af0 | 2115 | if (!(p->state & TASK_NORMAL)) |
2acca55e | 2116 | goto out; |
21aa9af0 | 2117 | |
fbd705a0 PZ |
2118 | trace_sched_waking(p); |
2119 | ||
e33a9bba TH |
2120 | if (!task_on_rq_queued(p)) { |
2121 | if (p->in_iowait) { | |
2122 | delayacct_blkio_end(); | |
2123 | atomic_dec(&rq->nr_iowait); | |
2124 | } | |
bce4dc80 | 2125 | ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK); |
e33a9bba | 2126 | } |
d7c01d27 | 2127 | |
d8ac8971 | 2128 | ttwu_do_wakeup(rq, p, 0, rf); |
4fa8d299 | 2129 | ttwu_stat(p, smp_processor_id(), 0); |
2acca55e PZ |
2130 | out: |
2131 | raw_spin_unlock(&p->pi_lock); | |
21aa9af0 TH |
2132 | } |
2133 | ||
50fa610a DH |
2134 | /** |
2135 | * wake_up_process - Wake up a specific process | |
2136 | * @p: The process to be woken up. | |
2137 | * | |
2138 | * Attempt to wake up the nominated process and move it to the set of runnable | |
e69f6186 YB |
2139 | * processes. |
2140 | * | |
2141 | * Return: 1 if the process was woken up, 0 if it was already running. | |
50fa610a DH |
2142 | * |
2143 | * It may be assumed that this function implies a write memory barrier before | |
2144 | * changing the task state if and only if any tasks are woken up. | |
2145 | */ | |
7ad5b3a5 | 2146 | int wake_up_process(struct task_struct *p) |
1da177e4 | 2147 | { |
9067ac85 | 2148 | return try_to_wake_up(p, TASK_NORMAL, 0); |
1da177e4 | 2149 | } |
1da177e4 LT |
2150 | EXPORT_SYMBOL(wake_up_process); |
2151 | ||
7ad5b3a5 | 2152 | int wake_up_state(struct task_struct *p, unsigned int state) |
1da177e4 LT |
2153 | { |
2154 | return try_to_wake_up(p, state, 0); | |
2155 | } | |
2156 | ||
1da177e4 LT |
2157 | /* |
2158 | * Perform scheduler related setup for a newly forked process p. | |
2159 | * p is forked by current. | |
dd41f596 IM |
2160 | * |
2161 | * __sched_fork() is basic setup used by init_idle() too: | |
2162 | */ | |
5e1576ed | 2163 | static void __sched_fork(unsigned long clone_flags, struct task_struct *p) |
dd41f596 | 2164 | { |
fd2f4419 PZ |
2165 | p->on_rq = 0; |
2166 | ||
2167 | p->se.on_rq = 0; | |
dd41f596 IM |
2168 | p->se.exec_start = 0; |
2169 | p->se.sum_exec_runtime = 0; | |
f6cf891c | 2170 | p->se.prev_sum_exec_runtime = 0; |
6c594c21 | 2171 | p->se.nr_migrations = 0; |
da7a735e | 2172 | p->se.vruntime = 0; |
fd2f4419 | 2173 | INIT_LIST_HEAD(&p->se.group_node); |
6cfb0d5d | 2174 | |
ad936d86 BP |
2175 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2176 | p->se.cfs_rq = NULL; | |
2177 | #endif | |
2178 | ||
6cfb0d5d | 2179 | #ifdef CONFIG_SCHEDSTATS |
cb251765 | 2180 | /* Even if schedstat is disabled, there should not be garbage */ |
41acab88 | 2181 | memset(&p->se.statistics, 0, sizeof(p->se.statistics)); |
6cfb0d5d | 2182 | #endif |
476d139c | 2183 | |
aab03e05 | 2184 | RB_CLEAR_NODE(&p->dl.rb_node); |
40767b0d | 2185 | init_dl_task_timer(&p->dl); |
209a0cbd | 2186 | init_dl_inactive_task_timer(&p->dl); |
a5e7be3b | 2187 | __dl_clear_params(p); |
aab03e05 | 2188 | |
fa717060 | 2189 | INIT_LIST_HEAD(&p->rt.run_list); |
ff77e468 PZ |
2190 | p->rt.timeout = 0; |
2191 | p->rt.time_slice = sched_rr_timeslice; | |
2192 | p->rt.on_rq = 0; | |
2193 | p->rt.on_list = 0; | |
476d139c | 2194 | |
e107be36 AK |
2195 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
2196 | INIT_HLIST_HEAD(&p->preempt_notifiers); | |
2197 | #endif | |
cbee9f88 PZ |
2198 | |
2199 | #ifdef CONFIG_NUMA_BALANCING | |
2200 | if (p->mm && atomic_read(&p->mm->mm_users) == 1) { | |
7e8d16b6 | 2201 | p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); |
cbee9f88 PZ |
2202 | p->mm->numa_scan_seq = 0; |
2203 | } | |
2204 | ||
5e1576ed RR |
2205 | if (clone_flags & CLONE_VM) |
2206 | p->numa_preferred_nid = current->numa_preferred_nid; | |
2207 | else | |
2208 | p->numa_preferred_nid = -1; | |
2209 | ||
cbee9f88 PZ |
2210 | p->node_stamp = 0ULL; |
2211 | p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; | |
4b96a29b | 2212 | p->numa_scan_period = sysctl_numa_balancing_scan_delay; |
cbee9f88 | 2213 | p->numa_work.next = &p->numa_work; |
44dba3d5 | 2214 | p->numa_faults = NULL; |
7e2703e6 RR |
2215 | p->last_task_numa_placement = 0; |
2216 | p->last_sum_exec_runtime = 0; | |
8c8a743c | 2217 | |
8c8a743c | 2218 | p->numa_group = NULL; |
cbee9f88 | 2219 | #endif /* CONFIG_NUMA_BALANCING */ |
dd41f596 IM |
2220 | } |
2221 | ||
2a595721 SD |
2222 | DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); |
2223 | ||
1a687c2e | 2224 | #ifdef CONFIG_NUMA_BALANCING |
c3b9bc5b | 2225 | |
1a687c2e MG |
2226 | void set_numabalancing_state(bool enabled) |
2227 | { | |
2228 | if (enabled) | |
2a595721 | 2229 | static_branch_enable(&sched_numa_balancing); |
1a687c2e | 2230 | else |
2a595721 | 2231 | static_branch_disable(&sched_numa_balancing); |
1a687c2e | 2232 | } |
54a43d54 AK |
2233 | |
2234 | #ifdef CONFIG_PROC_SYSCTL | |
2235 | int sysctl_numa_balancing(struct ctl_table *table, int write, | |
2236 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2237 | { | |
2238 | struct ctl_table t; | |
2239 | int err; | |
2a595721 | 2240 | int state = static_branch_likely(&sched_numa_balancing); |
54a43d54 AK |
2241 | |
2242 | if (write && !capable(CAP_SYS_ADMIN)) | |
2243 | return -EPERM; | |
2244 | ||
2245 | t = *table; | |
2246 | t.data = &state; | |
2247 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2248 | if (err < 0) | |
2249 | return err; | |
2250 | if (write) | |
2251 | set_numabalancing_state(state); | |
2252 | return err; | |
2253 | } | |
2254 | #endif | |
2255 | #endif | |
dd41f596 | 2256 | |
4698f88c JP |
2257 | #ifdef CONFIG_SCHEDSTATS |
2258 | ||
cb251765 | 2259 | DEFINE_STATIC_KEY_FALSE(sched_schedstats); |
4698f88c | 2260 | static bool __initdata __sched_schedstats = false; |
cb251765 | 2261 | |
cb251765 MG |
2262 | static void set_schedstats(bool enabled) |
2263 | { | |
2264 | if (enabled) | |
2265 | static_branch_enable(&sched_schedstats); | |
2266 | else | |
2267 | static_branch_disable(&sched_schedstats); | |
2268 | } | |
2269 | ||
2270 | void force_schedstat_enabled(void) | |
2271 | { | |
2272 | if (!schedstat_enabled()) { | |
2273 | pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); | |
2274 | static_branch_enable(&sched_schedstats); | |
2275 | } | |
2276 | } | |
2277 | ||
2278 | static int __init setup_schedstats(char *str) | |
2279 | { | |
2280 | int ret = 0; | |
2281 | if (!str) | |
2282 | goto out; | |
2283 | ||
4698f88c JP |
2284 | /* |
2285 | * This code is called before jump labels have been set up, so we can't | |
2286 | * change the static branch directly just yet. Instead set a temporary | |
2287 | * variable so init_schedstats() can do it later. | |
2288 | */ | |
cb251765 | 2289 | if (!strcmp(str, "enable")) { |
4698f88c | 2290 | __sched_schedstats = true; |
cb251765 MG |
2291 | ret = 1; |
2292 | } else if (!strcmp(str, "disable")) { | |
4698f88c | 2293 | __sched_schedstats = false; |
cb251765 MG |
2294 | ret = 1; |
2295 | } | |
2296 | out: | |
2297 | if (!ret) | |
2298 | pr_warn("Unable to parse schedstats=\n"); | |
2299 | ||
2300 | return ret; | |
2301 | } | |
2302 | __setup("schedstats=", setup_schedstats); | |
2303 | ||
4698f88c JP |
2304 | static void __init init_schedstats(void) |
2305 | { | |
2306 | set_schedstats(__sched_schedstats); | |
2307 | } | |
2308 | ||
cb251765 MG |
2309 | #ifdef CONFIG_PROC_SYSCTL |
2310 | int sysctl_schedstats(struct ctl_table *table, int write, | |
2311 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2312 | { | |
2313 | struct ctl_table t; | |
2314 | int err; | |
2315 | int state = static_branch_likely(&sched_schedstats); | |
2316 | ||
2317 | if (write && !capable(CAP_SYS_ADMIN)) | |
2318 | return -EPERM; | |
2319 | ||
2320 | t = *table; | |
2321 | t.data = &state; | |
2322 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2323 | if (err < 0) | |
2324 | return err; | |
2325 | if (write) | |
2326 | set_schedstats(state); | |
2327 | return err; | |
2328 | } | |
4698f88c JP |
2329 | #endif /* CONFIG_PROC_SYSCTL */ |
2330 | #else /* !CONFIG_SCHEDSTATS */ | |
2331 | static inline void init_schedstats(void) {} | |
2332 | #endif /* CONFIG_SCHEDSTATS */ | |
dd41f596 IM |
2333 | |
2334 | /* | |
2335 | * fork()/clone()-time setup: | |
2336 | */ | |
aab03e05 | 2337 | int sched_fork(unsigned long clone_flags, struct task_struct *p) |
dd41f596 | 2338 | { |
0122ec5b | 2339 | unsigned long flags; |
dd41f596 IM |
2340 | int cpu = get_cpu(); |
2341 | ||
5e1576ed | 2342 | __sched_fork(clone_flags, p); |
06b83b5f | 2343 | /* |
7dc603c9 | 2344 | * We mark the process as NEW here. This guarantees that |
06b83b5f PZ |
2345 | * nobody will actually run it, and a signal or other external |
2346 | * event cannot wake it up and insert it on the runqueue either. | |
2347 | */ | |
7dc603c9 | 2348 | p->state = TASK_NEW; |
dd41f596 | 2349 | |
c350a04e MG |
2350 | /* |
2351 | * Make sure we do not leak PI boosting priority to the child. | |
2352 | */ | |
2353 | p->prio = current->normal_prio; | |
2354 | ||
b9dc29e7 MG |
2355 | /* |
2356 | * Revert to default priority/policy on fork if requested. | |
2357 | */ | |
2358 | if (unlikely(p->sched_reset_on_fork)) { | |
aab03e05 | 2359 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
b9dc29e7 | 2360 | p->policy = SCHED_NORMAL; |
6c697bdf | 2361 | p->static_prio = NICE_TO_PRIO(0); |
c350a04e MG |
2362 | p->rt_priority = 0; |
2363 | } else if (PRIO_TO_NICE(p->static_prio) < 0) | |
2364 | p->static_prio = NICE_TO_PRIO(0); | |
2365 | ||
2366 | p->prio = p->normal_prio = __normal_prio(p); | |
9059393e | 2367 | set_load_weight(p, false); |
6c697bdf | 2368 | |
b9dc29e7 MG |
2369 | /* |
2370 | * We don't need the reset flag anymore after the fork. It has | |
2371 | * fulfilled its duty: | |
2372 | */ | |
2373 | p->sched_reset_on_fork = 0; | |
2374 | } | |
ca94c442 | 2375 | |
aab03e05 DF |
2376 | if (dl_prio(p->prio)) { |
2377 | put_cpu(); | |
2378 | return -EAGAIN; | |
2379 | } else if (rt_prio(p->prio)) { | |
2380 | p->sched_class = &rt_sched_class; | |
2381 | } else { | |
2ddbf952 | 2382 | p->sched_class = &fair_sched_class; |
aab03e05 | 2383 | } |
b29739f9 | 2384 | |
7dc603c9 | 2385 | init_entity_runnable_average(&p->se); |
cd29fe6f | 2386 | |
86951599 PZ |
2387 | /* |
2388 | * The child is not yet in the pid-hash so no cgroup attach races, | |
2389 | * and the cgroup is pinned to this child due to cgroup_fork() | |
2390 | * is ran before sched_fork(). | |
2391 | * | |
2392 | * Silence PROVE_RCU. | |
2393 | */ | |
0122ec5b | 2394 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
e210bffd | 2395 | /* |
d1ccc66d | 2396 | * We're setting the CPU for the first time, we don't migrate, |
e210bffd PZ |
2397 | * so use __set_task_cpu(). |
2398 | */ | |
2399 | __set_task_cpu(p, cpu); | |
2400 | if (p->sched_class->task_fork) | |
2401 | p->sched_class->task_fork(p); | |
0122ec5b | 2402 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
5f3edc1b | 2403 | |
f6db8347 | 2404 | #ifdef CONFIG_SCHED_INFO |
dd41f596 | 2405 | if (likely(sched_info_on())) |
52f17b6c | 2406 | memset(&p->sched_info, 0, sizeof(p->sched_info)); |
1da177e4 | 2407 | #endif |
3ca7a440 PZ |
2408 | #if defined(CONFIG_SMP) |
2409 | p->on_cpu = 0; | |
4866cde0 | 2410 | #endif |
01028747 | 2411 | init_task_preempt_count(p); |
806c09a7 | 2412 | #ifdef CONFIG_SMP |
917b627d | 2413 | plist_node_init(&p->pushable_tasks, MAX_PRIO); |
1baca4ce | 2414 | RB_CLEAR_NODE(&p->pushable_dl_tasks); |
806c09a7 | 2415 | #endif |
917b627d | 2416 | |
476d139c | 2417 | put_cpu(); |
aab03e05 | 2418 | return 0; |
1da177e4 LT |
2419 | } |
2420 | ||
332ac17e DF |
2421 | unsigned long to_ratio(u64 period, u64 runtime) |
2422 | { | |
2423 | if (runtime == RUNTIME_INF) | |
c52f14d3 | 2424 | return BW_UNIT; |
332ac17e DF |
2425 | |
2426 | /* | |
2427 | * Doing this here saves a lot of checks in all | |
2428 | * the calling paths, and returning zero seems | |
2429 | * safe for them anyway. | |
2430 | */ | |
2431 | if (period == 0) | |
2432 | return 0; | |
2433 | ||
c52f14d3 | 2434 | return div64_u64(runtime << BW_SHIFT, period); |
332ac17e DF |
2435 | } |
2436 | ||
1da177e4 LT |
2437 | /* |
2438 | * wake_up_new_task - wake up a newly created task for the first time. | |
2439 | * | |
2440 | * This function will do some initial scheduler statistics housekeeping | |
2441 | * that must be done for every newly created context, then puts the task | |
2442 | * on the runqueue and wakes it. | |
2443 | */ | |
3e51e3ed | 2444 | void wake_up_new_task(struct task_struct *p) |
1da177e4 | 2445 | { |
eb580751 | 2446 | struct rq_flags rf; |
dd41f596 | 2447 | struct rq *rq; |
fabf318e | 2448 | |
eb580751 | 2449 | raw_spin_lock_irqsave(&p->pi_lock, rf.flags); |
7dc603c9 | 2450 | p->state = TASK_RUNNING; |
fabf318e PZ |
2451 | #ifdef CONFIG_SMP |
2452 | /* | |
2453 | * Fork balancing, do it here and not earlier because: | |
2454 | * - cpus_allowed can change in the fork path | |
d1ccc66d | 2455 | * - any previously selected CPU might disappear through hotplug |
e210bffd PZ |
2456 | * |
2457 | * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, | |
2458 | * as we're not fully set-up yet. | |
fabf318e | 2459 | */ |
e210bffd | 2460 | __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); |
0017d735 | 2461 | #endif |
b7fa30c9 | 2462 | rq = __task_rq_lock(p, &rf); |
4126bad6 | 2463 | update_rq_clock(rq); |
2b8c41da | 2464 | post_init_entity_util_avg(&p->se); |
0017d735 | 2465 | |
7a57f32a | 2466 | activate_task(rq, p, ENQUEUE_NOCLOCK); |
da0c1e65 | 2467 | p->on_rq = TASK_ON_RQ_QUEUED; |
fbd705a0 | 2468 | trace_sched_wakeup_new(p); |
a7558e01 | 2469 | check_preempt_curr(rq, p, WF_FORK); |
9a897c5a | 2470 | #ifdef CONFIG_SMP |
0aaafaab PZ |
2471 | if (p->sched_class->task_woken) { |
2472 | /* | |
2473 | * Nothing relies on rq->lock after this, so its fine to | |
2474 | * drop it. | |
2475 | */ | |
d8ac8971 | 2476 | rq_unpin_lock(rq, &rf); |
efbbd05a | 2477 | p->sched_class->task_woken(rq, p); |
d8ac8971 | 2478 | rq_repin_lock(rq, &rf); |
0aaafaab | 2479 | } |
9a897c5a | 2480 | #endif |
eb580751 | 2481 | task_rq_unlock(rq, p, &rf); |
1da177e4 LT |
2482 | } |
2483 | ||
e107be36 AK |
2484 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
2485 | ||
1cde2930 PZ |
2486 | static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE; |
2487 | ||
2ecd9d29 PZ |
2488 | void preempt_notifier_inc(void) |
2489 | { | |
2490 | static_key_slow_inc(&preempt_notifier_key); | |
2491 | } | |
2492 | EXPORT_SYMBOL_GPL(preempt_notifier_inc); | |
2493 | ||
2494 | void preempt_notifier_dec(void) | |
2495 | { | |
2496 | static_key_slow_dec(&preempt_notifier_key); | |
2497 | } | |
2498 | EXPORT_SYMBOL_GPL(preempt_notifier_dec); | |
2499 | ||
e107be36 | 2500 | /** |
80dd99b3 | 2501 | * preempt_notifier_register - tell me when current is being preempted & rescheduled |
421cee29 | 2502 | * @notifier: notifier struct to register |
e107be36 AK |
2503 | */ |
2504 | void preempt_notifier_register(struct preempt_notifier *notifier) | |
2505 | { | |
2ecd9d29 PZ |
2506 | if (!static_key_false(&preempt_notifier_key)) |
2507 | WARN(1, "registering preempt_notifier while notifiers disabled\n"); | |
2508 | ||
e107be36 AK |
2509 | hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); |
2510 | } | |
2511 | EXPORT_SYMBOL_GPL(preempt_notifier_register); | |
2512 | ||
2513 | /** | |
2514 | * preempt_notifier_unregister - no longer interested in preemption notifications | |
421cee29 | 2515 | * @notifier: notifier struct to unregister |
e107be36 | 2516 | * |
d84525a8 | 2517 | * This is *not* safe to call from within a preemption notifier. |
e107be36 AK |
2518 | */ |
2519 | void preempt_notifier_unregister(struct preempt_notifier *notifier) | |
2520 | { | |
2521 | hlist_del(¬ifier->link); | |
2522 | } | |
2523 | EXPORT_SYMBOL_GPL(preempt_notifier_unregister); | |
2524 | ||
1cde2930 | 2525 | static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) |
e107be36 AK |
2526 | { |
2527 | struct preempt_notifier *notifier; | |
e107be36 | 2528 | |
b67bfe0d | 2529 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
e107be36 AK |
2530 | notifier->ops->sched_in(notifier, raw_smp_processor_id()); |
2531 | } | |
2532 | ||
1cde2930 PZ |
2533 | static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
2534 | { | |
2535 | if (static_key_false(&preempt_notifier_key)) | |
2536 | __fire_sched_in_preempt_notifiers(curr); | |
2537 | } | |
2538 | ||
e107be36 | 2539 | static void |
1cde2930 PZ |
2540 | __fire_sched_out_preempt_notifiers(struct task_struct *curr, |
2541 | struct task_struct *next) | |
e107be36 AK |
2542 | { |
2543 | struct preempt_notifier *notifier; | |
e107be36 | 2544 | |
b67bfe0d | 2545 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
e107be36 AK |
2546 | notifier->ops->sched_out(notifier, next); |
2547 | } | |
2548 | ||
1cde2930 PZ |
2549 | static __always_inline void |
2550 | fire_sched_out_preempt_notifiers(struct task_struct *curr, | |
2551 | struct task_struct *next) | |
2552 | { | |
2553 | if (static_key_false(&preempt_notifier_key)) | |
2554 | __fire_sched_out_preempt_notifiers(curr, next); | |
2555 | } | |
2556 | ||
6d6bc0ad | 2557 | #else /* !CONFIG_PREEMPT_NOTIFIERS */ |
e107be36 | 2558 | |
1cde2930 | 2559 | static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
e107be36 AK |
2560 | { |
2561 | } | |
2562 | ||
1cde2930 | 2563 | static inline void |
e107be36 AK |
2564 | fire_sched_out_preempt_notifiers(struct task_struct *curr, |
2565 | struct task_struct *next) | |
2566 | { | |
2567 | } | |
2568 | ||
6d6bc0ad | 2569 | #endif /* CONFIG_PREEMPT_NOTIFIERS */ |
e107be36 | 2570 | |
4866cde0 NP |
2571 | /** |
2572 | * prepare_task_switch - prepare to switch tasks | |
2573 | * @rq: the runqueue preparing to switch | |
421cee29 | 2574 | * @prev: the current task that is being switched out |
4866cde0 NP |
2575 | * @next: the task we are going to switch to. |
2576 | * | |
2577 | * This is called with the rq lock held and interrupts off. It must | |
2578 | * be paired with a subsequent finish_task_switch after the context | |
2579 | * switch. | |
2580 | * | |
2581 | * prepare_task_switch sets up locking and calls architecture specific | |
2582 | * hooks. | |
2583 | */ | |
e107be36 AK |
2584 | static inline void |
2585 | prepare_task_switch(struct rq *rq, struct task_struct *prev, | |
2586 | struct task_struct *next) | |
4866cde0 | 2587 | { |
43148951 | 2588 | sched_info_switch(rq, prev, next); |
fe4b04fa | 2589 | perf_event_task_sched_out(prev, next); |
e107be36 | 2590 | fire_sched_out_preempt_notifiers(prev, next); |
4866cde0 NP |
2591 | prepare_lock_switch(rq, next); |
2592 | prepare_arch_switch(next); | |
2593 | } | |
2594 | ||
1da177e4 LT |
2595 | /** |
2596 | * finish_task_switch - clean up after a task-switch | |
2597 | * @prev: the thread we just switched away from. | |
2598 | * | |
4866cde0 NP |
2599 | * finish_task_switch must be called after the context switch, paired |
2600 | * with a prepare_task_switch call before the context switch. | |
2601 | * finish_task_switch will reconcile locking set up by prepare_task_switch, | |
2602 | * and do any other architecture-specific cleanup actions. | |
1da177e4 LT |
2603 | * |
2604 | * Note that we may have delayed dropping an mm in context_switch(). If | |
41a2d6cf | 2605 | * so, we finish that here outside of the runqueue lock. (Doing it |
1da177e4 LT |
2606 | * with the lock held can cause deadlocks; see schedule() for |
2607 | * details.) | |
dfa50b60 ON |
2608 | * |
2609 | * The context switch have flipped the stack from under us and restored the | |
2610 | * local variables which were saved when this task called schedule() in the | |
2611 | * past. prev == current is still correct but we need to recalculate this_rq | |
2612 | * because prev may have moved to another CPU. | |
1da177e4 | 2613 | */ |
dfa50b60 | 2614 | static struct rq *finish_task_switch(struct task_struct *prev) |
1da177e4 LT |
2615 | __releases(rq->lock) |
2616 | { | |
dfa50b60 | 2617 | struct rq *rq = this_rq(); |
1da177e4 | 2618 | struct mm_struct *mm = rq->prev_mm; |
55a101f8 | 2619 | long prev_state; |
1da177e4 | 2620 | |
609ca066 PZ |
2621 | /* |
2622 | * The previous task will have left us with a preempt_count of 2 | |
2623 | * because it left us after: | |
2624 | * | |
2625 | * schedule() | |
2626 | * preempt_disable(); // 1 | |
2627 | * __schedule() | |
2628 | * raw_spin_lock_irq(&rq->lock) // 2 | |
2629 | * | |
2630 | * Also, see FORK_PREEMPT_COUNT. | |
2631 | */ | |
e2bf1c4b PZ |
2632 | if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, |
2633 | "corrupted preempt_count: %s/%d/0x%x\n", | |
2634 | current->comm, current->pid, preempt_count())) | |
2635 | preempt_count_set(FORK_PREEMPT_COUNT); | |
609ca066 | 2636 | |
1da177e4 LT |
2637 | rq->prev_mm = NULL; |
2638 | ||
2639 | /* | |
2640 | * A task struct has one reference for the use as "current". | |
c394cc9f | 2641 | * If a task dies, then it sets TASK_DEAD in tsk->state and calls |
55a101f8 ON |
2642 | * schedule one last time. The schedule call will never return, and |
2643 | * the scheduled task must drop that reference. | |
95913d97 PZ |
2644 | * |
2645 | * We must observe prev->state before clearing prev->on_cpu (in | |
2646 | * finish_lock_switch), otherwise a concurrent wakeup can get prev | |
2647 | * running on another CPU and we could rave with its RUNNING -> DEAD | |
2648 | * transition, resulting in a double drop. | |
1da177e4 | 2649 | */ |
55a101f8 | 2650 | prev_state = prev->state; |
bf9fae9f | 2651 | vtime_task_switch(prev); |
a8d757ef | 2652 | perf_event_task_sched_in(prev, current); |
22e4ebb9 MD |
2653 | /* |
2654 | * The membarrier system call requires a full memory barrier | |
2655 | * after storing to rq->curr, before going back to user-space. | |
2656 | * | |
2657 | * TODO: This smp_mb__after_unlock_lock can go away if PPC end | |
2658 | * up adding a full barrier to switch_mm(), or we should figure | |
2659 | * out if a smp_mb__after_unlock_lock is really the proper API | |
2660 | * to use. | |
2661 | */ | |
2662 | smp_mb__after_unlock_lock(); | |
4866cde0 | 2663 | finish_lock_switch(rq, prev); |
01f23e16 | 2664 | finish_arch_post_lock_switch(); |
e8fa1362 | 2665 | |
e107be36 | 2666 | fire_sched_in_preempt_notifiers(current); |
1da177e4 LT |
2667 | if (mm) |
2668 | mmdrop(mm); | |
c394cc9f | 2669 | if (unlikely(prev_state == TASK_DEAD)) { |
e6c390f2 DF |
2670 | if (prev->sched_class->task_dead) |
2671 | prev->sched_class->task_dead(prev); | |
2672 | ||
c6fd91f0 | 2673 | /* |
2674 | * Remove function-return probe instances associated with this | |
2675 | * task and put them back on the free list. | |
9761eea8 | 2676 | */ |
c6fd91f0 | 2677 | kprobe_flush_task(prev); |
68f24b08 AL |
2678 | |
2679 | /* Task is done with its stack. */ | |
2680 | put_task_stack(prev); | |
2681 | ||
1da177e4 | 2682 | put_task_struct(prev); |
c6fd91f0 | 2683 | } |
99e5ada9 | 2684 | |
de734f89 | 2685 | tick_nohz_task_switch(); |
dfa50b60 | 2686 | return rq; |
1da177e4 LT |
2687 | } |
2688 | ||
3f029d3c GH |
2689 | #ifdef CONFIG_SMP |
2690 | ||
3f029d3c | 2691 | /* rq->lock is NOT held, but preemption is disabled */ |
e3fca9e7 | 2692 | static void __balance_callback(struct rq *rq) |
3f029d3c | 2693 | { |
e3fca9e7 PZ |
2694 | struct callback_head *head, *next; |
2695 | void (*func)(struct rq *rq); | |
2696 | unsigned long flags; | |
3f029d3c | 2697 | |
e3fca9e7 PZ |
2698 | raw_spin_lock_irqsave(&rq->lock, flags); |
2699 | head = rq->balance_callback; | |
2700 | rq->balance_callback = NULL; | |
2701 | while (head) { | |
2702 | func = (void (*)(struct rq *))head->func; | |
2703 | next = head->next; | |
2704 | head->next = NULL; | |
2705 | head = next; | |
3f029d3c | 2706 | |
e3fca9e7 | 2707 | func(rq); |
3f029d3c | 2708 | } |
e3fca9e7 PZ |
2709 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
2710 | } | |
2711 | ||
2712 | static inline void balance_callback(struct rq *rq) | |
2713 | { | |
2714 | if (unlikely(rq->balance_callback)) | |
2715 | __balance_callback(rq); | |
3f029d3c GH |
2716 | } |
2717 | ||
2718 | #else | |
da19ab51 | 2719 | |
e3fca9e7 | 2720 | static inline void balance_callback(struct rq *rq) |
3f029d3c | 2721 | { |
1da177e4 LT |
2722 | } |
2723 | ||
3f029d3c GH |
2724 | #endif |
2725 | ||
1da177e4 LT |
2726 | /** |
2727 | * schedule_tail - first thing a freshly forked thread must call. | |
2728 | * @prev: the thread we just switched away from. | |
2729 | */ | |
722a9f92 | 2730 | asmlinkage __visible void schedule_tail(struct task_struct *prev) |
1da177e4 LT |
2731 | __releases(rq->lock) |
2732 | { | |
1a43a14a | 2733 | struct rq *rq; |
da19ab51 | 2734 | |
609ca066 PZ |
2735 | /* |
2736 | * New tasks start with FORK_PREEMPT_COUNT, see there and | |
2737 | * finish_task_switch() for details. | |
2738 | * | |
2739 | * finish_task_switch() will drop rq->lock() and lower preempt_count | |
2740 | * and the preempt_enable() will end up enabling preemption (on | |
2741 | * PREEMPT_COUNT kernels). | |
2742 | */ | |
2743 | ||
dfa50b60 | 2744 | rq = finish_task_switch(prev); |
e3fca9e7 | 2745 | balance_callback(rq); |
1a43a14a | 2746 | preempt_enable(); |
70b97a7f | 2747 | |
1da177e4 | 2748 | if (current->set_child_tid) |
b488893a | 2749 | put_user(task_pid_vnr(current), current->set_child_tid); |
1da177e4 LT |
2750 | } |
2751 | ||
2752 | /* | |
dfa50b60 | 2753 | * context_switch - switch to the new MM and the new thread's register state. |
1da177e4 | 2754 | */ |
04936948 | 2755 | static __always_inline struct rq * |
70b97a7f | 2756 | context_switch(struct rq *rq, struct task_struct *prev, |
d8ac8971 | 2757 | struct task_struct *next, struct rq_flags *rf) |
1da177e4 | 2758 | { |
dd41f596 | 2759 | struct mm_struct *mm, *oldmm; |
1da177e4 | 2760 | |
e107be36 | 2761 | prepare_task_switch(rq, prev, next); |
fe4b04fa | 2762 | |
dd41f596 IM |
2763 | mm = next->mm; |
2764 | oldmm = prev->active_mm; | |
9226d125 ZA |
2765 | /* |
2766 | * For paravirt, this is coupled with an exit in switch_to to | |
2767 | * combine the page table reload and the switch backend into | |
2768 | * one hypercall. | |
2769 | */ | |
224101ed | 2770 | arch_start_context_switch(prev); |
9226d125 | 2771 | |
31915ab4 | 2772 | if (!mm) { |
1da177e4 | 2773 | next->active_mm = oldmm; |
f1f10076 | 2774 | mmgrab(oldmm); |
1da177e4 LT |
2775 | enter_lazy_tlb(oldmm, next); |
2776 | } else | |
f98db601 | 2777 | switch_mm_irqs_off(oldmm, mm, next); |
1da177e4 | 2778 | |
31915ab4 | 2779 | if (!prev->mm) { |
1da177e4 | 2780 | prev->active_mm = NULL; |
1da177e4 LT |
2781 | rq->prev_mm = oldmm; |
2782 | } | |
92509b73 | 2783 | |
cb42c9a3 | 2784 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
92509b73 | 2785 | |
3a5f5e48 IM |
2786 | /* |
2787 | * Since the runqueue lock will be released by the next | |
2788 | * task (which is an invalid locking op but in the case | |
2789 | * of the scheduler it's an obvious special-case), so we | |
2790 | * do an early lockdep release here: | |
2791 | */ | |
d8ac8971 | 2792 | rq_unpin_lock(rq, rf); |
8a25d5de | 2793 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); |
1da177e4 LT |
2794 | |
2795 | /* Here we just switch the register state and the stack. */ | |
2796 | switch_to(prev, next, prev); | |
dd41f596 | 2797 | barrier(); |
dfa50b60 ON |
2798 | |
2799 | return finish_task_switch(prev); | |
1da177e4 LT |
2800 | } |
2801 | ||
2802 | /* | |
1c3e8264 | 2803 | * nr_running and nr_context_switches: |
1da177e4 LT |
2804 | * |
2805 | * externally visible scheduler statistics: current number of runnable | |
1c3e8264 | 2806 | * threads, total number of context switches performed since bootup. |
1da177e4 LT |
2807 | */ |
2808 | unsigned long nr_running(void) | |
2809 | { | |
2810 | unsigned long i, sum = 0; | |
2811 | ||
2812 | for_each_online_cpu(i) | |
2813 | sum += cpu_rq(i)->nr_running; | |
2814 | ||
2815 | return sum; | |
f711f609 | 2816 | } |
1da177e4 | 2817 | |
2ee507c4 | 2818 | /* |
d1ccc66d | 2819 | * Check if only the current task is running on the CPU. |
00cc1633 DD |
2820 | * |
2821 | * Caution: this function does not check that the caller has disabled | |
2822 | * preemption, thus the result might have a time-of-check-to-time-of-use | |
2823 | * race. The caller is responsible to use it correctly, for example: | |
2824 | * | |
2825 | * - from a non-preemptable section (of course) | |
2826 | * | |
2827 | * - from a thread that is bound to a single CPU | |
2828 | * | |
2829 | * - in a loop with very short iterations (e.g. a polling loop) | |
2ee507c4 TC |
2830 | */ |
2831 | bool single_task_running(void) | |
2832 | { | |
00cc1633 | 2833 | return raw_rq()->nr_running == 1; |
2ee507c4 TC |
2834 | } |
2835 | EXPORT_SYMBOL(single_task_running); | |
2836 | ||
1da177e4 | 2837 | unsigned long long nr_context_switches(void) |
46cb4b7c | 2838 | { |
cc94abfc SR |
2839 | int i; |
2840 | unsigned long long sum = 0; | |
46cb4b7c | 2841 | |
0a945022 | 2842 | for_each_possible_cpu(i) |
1da177e4 | 2843 | sum += cpu_rq(i)->nr_switches; |
46cb4b7c | 2844 | |
1da177e4 LT |
2845 | return sum; |
2846 | } | |
483b4ee6 | 2847 | |
e33a9bba TH |
2848 | /* |
2849 | * IO-wait accounting, and how its mostly bollocks (on SMP). | |
2850 | * | |
2851 | * The idea behind IO-wait account is to account the idle time that we could | |
2852 | * have spend running if it were not for IO. That is, if we were to improve the | |
2853 | * storage performance, we'd have a proportional reduction in IO-wait time. | |
2854 | * | |
2855 | * This all works nicely on UP, where, when a task blocks on IO, we account | |
2856 | * idle time as IO-wait, because if the storage were faster, it could've been | |
2857 | * running and we'd not be idle. | |
2858 | * | |
2859 | * This has been extended to SMP, by doing the same for each CPU. This however | |
2860 | * is broken. | |
2861 | * | |
2862 | * Imagine for instance the case where two tasks block on one CPU, only the one | |
2863 | * CPU will have IO-wait accounted, while the other has regular idle. Even | |
2864 | * though, if the storage were faster, both could've ran at the same time, | |
2865 | * utilising both CPUs. | |
2866 | * | |
2867 | * This means, that when looking globally, the current IO-wait accounting on | |
2868 | * SMP is a lower bound, by reason of under accounting. | |
2869 | * | |
2870 | * Worse, since the numbers are provided per CPU, they are sometimes | |
2871 | * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly | |
2872 | * associated with any one particular CPU, it can wake to another CPU than it | |
2873 | * blocked on. This means the per CPU IO-wait number is meaningless. | |
2874 | * | |
2875 | * Task CPU affinities can make all that even more 'interesting'. | |
2876 | */ | |
2877 | ||
1da177e4 LT |
2878 | unsigned long nr_iowait(void) |
2879 | { | |
2880 | unsigned long i, sum = 0; | |
483b4ee6 | 2881 | |
0a945022 | 2882 | for_each_possible_cpu(i) |
1da177e4 | 2883 | sum += atomic_read(&cpu_rq(i)->nr_iowait); |
46cb4b7c | 2884 | |
1da177e4 LT |
2885 | return sum; |
2886 | } | |
483b4ee6 | 2887 | |
e33a9bba TH |
2888 | /* |
2889 | * Consumers of these two interfaces, like for example the cpufreq menu | |
2890 | * governor are using nonsensical data. Boosting frequency for a CPU that has | |
2891 | * IO-wait which might not even end up running the task when it does become | |
2892 | * runnable. | |
2893 | */ | |
2894 | ||
8c215bd3 | 2895 | unsigned long nr_iowait_cpu(int cpu) |
69d25870 | 2896 | { |
8c215bd3 | 2897 | struct rq *this = cpu_rq(cpu); |
69d25870 AV |
2898 | return atomic_read(&this->nr_iowait); |
2899 | } | |
46cb4b7c | 2900 | |
372ba8cb MG |
2901 | void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) |
2902 | { | |
3289bdb4 PZ |
2903 | struct rq *rq = this_rq(); |
2904 | *nr_waiters = atomic_read(&rq->nr_iowait); | |
2905 | *load = rq->load.weight; | |
372ba8cb MG |
2906 | } |
2907 | ||
dd41f596 | 2908 | #ifdef CONFIG_SMP |
8a0be9ef | 2909 | |
46cb4b7c | 2910 | /* |
38022906 PZ |
2911 | * sched_exec - execve() is a valuable balancing opportunity, because at |
2912 | * this point the task has the smallest effective memory and cache footprint. | |
46cb4b7c | 2913 | */ |
38022906 | 2914 | void sched_exec(void) |
46cb4b7c | 2915 | { |
38022906 | 2916 | struct task_struct *p = current; |
1da177e4 | 2917 | unsigned long flags; |
0017d735 | 2918 | int dest_cpu; |
46cb4b7c | 2919 | |
8f42ced9 | 2920 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
ac66f547 | 2921 | dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); |
0017d735 PZ |
2922 | if (dest_cpu == smp_processor_id()) |
2923 | goto unlock; | |
38022906 | 2924 | |
8f42ced9 | 2925 | if (likely(cpu_active(dest_cpu))) { |
969c7921 | 2926 | struct migration_arg arg = { p, dest_cpu }; |
46cb4b7c | 2927 | |
8f42ced9 PZ |
2928 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
2929 | stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); | |
1da177e4 LT |
2930 | return; |
2931 | } | |
0017d735 | 2932 | unlock: |
8f42ced9 | 2933 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 | 2934 | } |
dd41f596 | 2935 | |
1da177e4 LT |
2936 | #endif |
2937 | ||
1da177e4 | 2938 | DEFINE_PER_CPU(struct kernel_stat, kstat); |
3292beb3 | 2939 | DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); |
1da177e4 LT |
2940 | |
2941 | EXPORT_PER_CPU_SYMBOL(kstat); | |
3292beb3 | 2942 | EXPORT_PER_CPU_SYMBOL(kernel_cpustat); |
1da177e4 | 2943 | |
6075620b GG |
2944 | /* |
2945 | * The function fair_sched_class.update_curr accesses the struct curr | |
2946 | * and its field curr->exec_start; when called from task_sched_runtime(), | |
2947 | * we observe a high rate of cache misses in practice. | |
2948 | * Prefetching this data results in improved performance. | |
2949 | */ | |
2950 | static inline void prefetch_curr_exec_start(struct task_struct *p) | |
2951 | { | |
2952 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
2953 | struct sched_entity *curr = (&p->se)->cfs_rq->curr; | |
2954 | #else | |
2955 | struct sched_entity *curr = (&task_rq(p)->cfs)->curr; | |
2956 | #endif | |
2957 | prefetch(curr); | |
2958 | prefetch(&curr->exec_start); | |
2959 | } | |
2960 | ||
c5f8d995 HS |
2961 | /* |
2962 | * Return accounted runtime for the task. | |
2963 | * In case the task is currently running, return the runtime plus current's | |
2964 | * pending runtime that have not been accounted yet. | |
2965 | */ | |
2966 | unsigned long long task_sched_runtime(struct task_struct *p) | |
2967 | { | |
eb580751 | 2968 | struct rq_flags rf; |
c5f8d995 | 2969 | struct rq *rq; |
6e998916 | 2970 | u64 ns; |
c5f8d995 | 2971 | |
911b2898 PZ |
2972 | #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) |
2973 | /* | |
2974 | * 64-bit doesn't need locks to atomically read a 64bit value. | |
2975 | * So we have a optimization chance when the task's delta_exec is 0. | |
2976 | * Reading ->on_cpu is racy, but this is ok. | |
2977 | * | |
d1ccc66d IM |
2978 | * If we race with it leaving CPU, we'll take a lock. So we're correct. |
2979 | * If we race with it entering CPU, unaccounted time is 0. This is | |
911b2898 | 2980 | * indistinguishable from the read occurring a few cycles earlier. |
4036ac15 MG |
2981 | * If we see ->on_cpu without ->on_rq, the task is leaving, and has |
2982 | * been accounted, so we're correct here as well. | |
911b2898 | 2983 | */ |
da0c1e65 | 2984 | if (!p->on_cpu || !task_on_rq_queued(p)) |
911b2898 PZ |
2985 | return p->se.sum_exec_runtime; |
2986 | #endif | |
2987 | ||
eb580751 | 2988 | rq = task_rq_lock(p, &rf); |
6e998916 SG |
2989 | /* |
2990 | * Must be ->curr _and_ ->on_rq. If dequeued, we would | |
2991 | * project cycles that may never be accounted to this | |
2992 | * thread, breaking clock_gettime(). | |
2993 | */ | |
2994 | if (task_current(rq, p) && task_on_rq_queued(p)) { | |
6075620b | 2995 | prefetch_curr_exec_start(p); |
6e998916 SG |
2996 | update_rq_clock(rq); |
2997 | p->sched_class->update_curr(rq); | |
2998 | } | |
2999 | ns = p->se.sum_exec_runtime; | |
eb580751 | 3000 | task_rq_unlock(rq, p, &rf); |
c5f8d995 HS |
3001 | |
3002 | return ns; | |
3003 | } | |
48f24c4d | 3004 | |
7835b98b CL |
3005 | /* |
3006 | * This function gets called by the timer code, with HZ frequency. | |
3007 | * We call it with interrupts disabled. | |
7835b98b CL |
3008 | */ |
3009 | void scheduler_tick(void) | |
3010 | { | |
7835b98b CL |
3011 | int cpu = smp_processor_id(); |
3012 | struct rq *rq = cpu_rq(cpu); | |
dd41f596 | 3013 | struct task_struct *curr = rq->curr; |
8a8c69c3 | 3014 | struct rq_flags rf; |
3e51f33f PZ |
3015 | |
3016 | sched_clock_tick(); | |
dd41f596 | 3017 | |
8a8c69c3 PZ |
3018 | rq_lock(rq, &rf); |
3019 | ||
3e51f33f | 3020 | update_rq_clock(rq); |
fa85ae24 | 3021 | curr->sched_class->task_tick(rq, curr, 0); |
cee1afce | 3022 | cpu_load_update_active(rq); |
3289bdb4 | 3023 | calc_global_load_tick(rq); |
8a8c69c3 PZ |
3024 | |
3025 | rq_unlock(rq, &rf); | |
7835b98b | 3026 | |
e9d2b064 | 3027 | perf_event_task_tick(); |
e220d2dc | 3028 | |
e418e1c2 | 3029 | #ifdef CONFIG_SMP |
6eb57e0d | 3030 | rq->idle_balance = idle_cpu(cpu); |
7caff66f | 3031 | trigger_load_balance(rq); |
e418e1c2 | 3032 | #endif |
265f22a9 | 3033 | rq_last_tick_reset(rq); |
1da177e4 LT |
3034 | } |
3035 | ||
265f22a9 FW |
3036 | #ifdef CONFIG_NO_HZ_FULL |
3037 | /** | |
3038 | * scheduler_tick_max_deferment | |
3039 | * | |
3040 | * Keep at least one tick per second when a single | |
3041 | * active task is running because the scheduler doesn't | |
3042 | * yet completely support full dynticks environment. | |
3043 | * | |
3044 | * This makes sure that uptime, CFS vruntime, load | |
3045 | * balancing, etc... continue to move forward, even | |
3046 | * with a very low granularity. | |
e69f6186 YB |
3047 | * |
3048 | * Return: Maximum deferment in nanoseconds. | |
265f22a9 FW |
3049 | */ |
3050 | u64 scheduler_tick_max_deferment(void) | |
3051 | { | |
3052 | struct rq *rq = this_rq(); | |
316c1608 | 3053 | unsigned long next, now = READ_ONCE(jiffies); |
265f22a9 FW |
3054 | |
3055 | next = rq->last_sched_tick + HZ; | |
3056 | ||
3057 | if (time_before_eq(next, now)) | |
3058 | return 0; | |
3059 | ||
8fe8ff09 | 3060 | return jiffies_to_nsecs(next - now); |
1da177e4 | 3061 | } |
265f22a9 | 3062 | #endif |
1da177e4 | 3063 | |
7e49fcce SR |
3064 | #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ |
3065 | defined(CONFIG_PREEMPT_TRACER)) | |
47252cfb SR |
3066 | /* |
3067 | * If the value passed in is equal to the current preempt count | |
3068 | * then we just disabled preemption. Start timing the latency. | |
3069 | */ | |
3070 | static inline void preempt_latency_start(int val) | |
3071 | { | |
3072 | if (preempt_count() == val) { | |
3073 | unsigned long ip = get_lock_parent_ip(); | |
3074 | #ifdef CONFIG_DEBUG_PREEMPT | |
3075 | current->preempt_disable_ip = ip; | |
3076 | #endif | |
3077 | trace_preempt_off(CALLER_ADDR0, ip); | |
3078 | } | |
3079 | } | |
7e49fcce | 3080 | |
edafe3a5 | 3081 | void preempt_count_add(int val) |
1da177e4 | 3082 | { |
6cd8a4bb | 3083 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3084 | /* |
3085 | * Underflow? | |
3086 | */ | |
9a11b49a IM |
3087 | if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) |
3088 | return; | |
6cd8a4bb | 3089 | #endif |
bdb43806 | 3090 | __preempt_count_add(val); |
6cd8a4bb | 3091 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3092 | /* |
3093 | * Spinlock count overflowing soon? | |
3094 | */ | |
33859f7f MOS |
3095 | DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= |
3096 | PREEMPT_MASK - 10); | |
6cd8a4bb | 3097 | #endif |
47252cfb | 3098 | preempt_latency_start(val); |
1da177e4 | 3099 | } |
bdb43806 | 3100 | EXPORT_SYMBOL(preempt_count_add); |
edafe3a5 | 3101 | NOKPROBE_SYMBOL(preempt_count_add); |
1da177e4 | 3102 | |
47252cfb SR |
3103 | /* |
3104 | * If the value passed in equals to the current preempt count | |
3105 | * then we just enabled preemption. Stop timing the latency. | |
3106 | */ | |
3107 | static inline void preempt_latency_stop(int val) | |
3108 | { | |
3109 | if (preempt_count() == val) | |
3110 | trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); | |
3111 | } | |
3112 | ||
edafe3a5 | 3113 | void preempt_count_sub(int val) |
1da177e4 | 3114 | { |
6cd8a4bb | 3115 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3116 | /* |
3117 | * Underflow? | |
3118 | */ | |
01e3eb82 | 3119 | if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) |
9a11b49a | 3120 | return; |
1da177e4 LT |
3121 | /* |
3122 | * Is the spinlock portion underflowing? | |
3123 | */ | |
9a11b49a IM |
3124 | if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && |
3125 | !(preempt_count() & PREEMPT_MASK))) | |
3126 | return; | |
6cd8a4bb | 3127 | #endif |
9a11b49a | 3128 | |
47252cfb | 3129 | preempt_latency_stop(val); |
bdb43806 | 3130 | __preempt_count_sub(val); |
1da177e4 | 3131 | } |
bdb43806 | 3132 | EXPORT_SYMBOL(preempt_count_sub); |
edafe3a5 | 3133 | NOKPROBE_SYMBOL(preempt_count_sub); |
1da177e4 | 3134 | |
47252cfb SR |
3135 | #else |
3136 | static inline void preempt_latency_start(int val) { } | |
3137 | static inline void preempt_latency_stop(int val) { } | |
1da177e4 LT |
3138 | #endif |
3139 | ||
59ddbcb2 IM |
3140 | static inline unsigned long get_preempt_disable_ip(struct task_struct *p) |
3141 | { | |
3142 | #ifdef CONFIG_DEBUG_PREEMPT | |
3143 | return p->preempt_disable_ip; | |
3144 | #else | |
3145 | return 0; | |
3146 | #endif | |
3147 | } | |
3148 | ||
1da177e4 | 3149 | /* |
dd41f596 | 3150 | * Print scheduling while atomic bug: |
1da177e4 | 3151 | */ |
dd41f596 | 3152 | static noinline void __schedule_bug(struct task_struct *prev) |
1da177e4 | 3153 | { |
d1c6d149 VN |
3154 | /* Save this before calling printk(), since that will clobber it */ |
3155 | unsigned long preempt_disable_ip = get_preempt_disable_ip(current); | |
3156 | ||
664dfa65 DJ |
3157 | if (oops_in_progress) |
3158 | return; | |
3159 | ||
3df0fc5b PZ |
3160 | printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", |
3161 | prev->comm, prev->pid, preempt_count()); | |
838225b4 | 3162 | |
dd41f596 | 3163 | debug_show_held_locks(prev); |
e21f5b15 | 3164 | print_modules(); |
dd41f596 IM |
3165 | if (irqs_disabled()) |
3166 | print_irqtrace_events(prev); | |
d1c6d149 VN |
3167 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
3168 | && in_atomic_preempt_off()) { | |
8f47b187 | 3169 | pr_err("Preemption disabled at:"); |
d1c6d149 | 3170 | print_ip_sym(preempt_disable_ip); |
8f47b187 TG |
3171 | pr_cont("\n"); |
3172 | } | |
748c7201 DBO |
3173 | if (panic_on_warn) |
3174 | panic("scheduling while atomic\n"); | |
3175 | ||
6135fc1e | 3176 | dump_stack(); |
373d4d09 | 3177 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
dd41f596 | 3178 | } |
1da177e4 | 3179 | |
dd41f596 IM |
3180 | /* |
3181 | * Various schedule()-time debugging checks and statistics: | |
3182 | */ | |
3183 | static inline void schedule_debug(struct task_struct *prev) | |
3184 | { | |
0d9e2632 | 3185 | #ifdef CONFIG_SCHED_STACK_END_CHECK |
29d64551 JH |
3186 | if (task_stack_end_corrupted(prev)) |
3187 | panic("corrupted stack end detected inside scheduler\n"); | |
0d9e2632 | 3188 | #endif |
b99def8b | 3189 | |
1dc0fffc | 3190 | if (unlikely(in_atomic_preempt_off())) { |
dd41f596 | 3191 | __schedule_bug(prev); |
1dc0fffc PZ |
3192 | preempt_count_set(PREEMPT_DISABLED); |
3193 | } | |
b3fbab05 | 3194 | rcu_sleep_check(); |
dd41f596 | 3195 | |
1da177e4 LT |
3196 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); |
3197 | ||
ae92882e | 3198 | schedstat_inc(this_rq()->sched_count); |
dd41f596 IM |
3199 | } |
3200 | ||
3201 | /* | |
3202 | * Pick up the highest-prio task: | |
3203 | */ | |
3204 | static inline struct task_struct * | |
d8ac8971 | 3205 | pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
dd41f596 | 3206 | { |
49ee5768 | 3207 | const struct sched_class *class; |
dd41f596 | 3208 | struct task_struct *p; |
1da177e4 LT |
3209 | |
3210 | /* | |
0ba87bb2 PZ |
3211 | * Optimization: we know that if all tasks are in the fair class we can |
3212 | * call that function directly, but only if the @prev task wasn't of a | |
3213 | * higher scheduling class, because otherwise those loose the | |
3214 | * opportunity to pull in more work from other CPUs. | |
1da177e4 | 3215 | */ |
0ba87bb2 PZ |
3216 | if (likely((prev->sched_class == &idle_sched_class || |
3217 | prev->sched_class == &fair_sched_class) && | |
3218 | rq->nr_running == rq->cfs.h_nr_running)) { | |
3219 | ||
d8ac8971 | 3220 | p = fair_sched_class.pick_next_task(rq, prev, rf); |
6ccdc84b PZ |
3221 | if (unlikely(p == RETRY_TASK)) |
3222 | goto again; | |
3223 | ||
d1ccc66d | 3224 | /* Assumes fair_sched_class->next == idle_sched_class */ |
6ccdc84b | 3225 | if (unlikely(!p)) |
d8ac8971 | 3226 | p = idle_sched_class.pick_next_task(rq, prev, rf); |
6ccdc84b PZ |
3227 | |
3228 | return p; | |
1da177e4 LT |
3229 | } |
3230 | ||
37e117c0 | 3231 | again: |
34f971f6 | 3232 | for_each_class(class) { |
d8ac8971 | 3233 | p = class->pick_next_task(rq, prev, rf); |
37e117c0 PZ |
3234 | if (p) { |
3235 | if (unlikely(p == RETRY_TASK)) | |
3236 | goto again; | |
dd41f596 | 3237 | return p; |
37e117c0 | 3238 | } |
dd41f596 | 3239 | } |
34f971f6 | 3240 | |
d1ccc66d IM |
3241 | /* The idle class should always have a runnable task: */ |
3242 | BUG(); | |
dd41f596 | 3243 | } |
1da177e4 | 3244 | |
dd41f596 | 3245 | /* |
c259e01a | 3246 | * __schedule() is the main scheduler function. |
edde96ea PE |
3247 | * |
3248 | * The main means of driving the scheduler and thus entering this function are: | |
3249 | * | |
3250 | * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. | |
3251 | * | |
3252 | * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return | |
3253 | * paths. For example, see arch/x86/entry_64.S. | |
3254 | * | |
3255 | * To drive preemption between tasks, the scheduler sets the flag in timer | |
3256 | * interrupt handler scheduler_tick(). | |
3257 | * | |
3258 | * 3. Wakeups don't really cause entry into schedule(). They add a | |
3259 | * task to the run-queue and that's it. | |
3260 | * | |
3261 | * Now, if the new task added to the run-queue preempts the current | |
3262 | * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets | |
3263 | * called on the nearest possible occasion: | |
3264 | * | |
3265 | * - If the kernel is preemptible (CONFIG_PREEMPT=y): | |
3266 | * | |
3267 | * - in syscall or exception context, at the next outmost | |
3268 | * preempt_enable(). (this might be as soon as the wake_up()'s | |
3269 | * spin_unlock()!) | |
3270 | * | |
3271 | * - in IRQ context, return from interrupt-handler to | |
3272 | * preemptible context | |
3273 | * | |
3274 | * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) | |
3275 | * then at the next: | |
3276 | * | |
3277 | * - cond_resched() call | |
3278 | * - explicit schedule() call | |
3279 | * - return from syscall or exception to user-space | |
3280 | * - return from interrupt-handler to user-space | |
bfd9b2b5 | 3281 | * |
b30f0e3f | 3282 | * WARNING: must be called with preemption disabled! |
dd41f596 | 3283 | */ |
499d7955 | 3284 | static void __sched notrace __schedule(bool preempt) |
dd41f596 IM |
3285 | { |
3286 | struct task_struct *prev, *next; | |
67ca7bde | 3287 | unsigned long *switch_count; |
d8ac8971 | 3288 | struct rq_flags rf; |
dd41f596 | 3289 | struct rq *rq; |
31656519 | 3290 | int cpu; |
dd41f596 | 3291 | |
dd41f596 IM |
3292 | cpu = smp_processor_id(); |
3293 | rq = cpu_rq(cpu); | |
dd41f596 | 3294 | prev = rq->curr; |
dd41f596 | 3295 | |
dd41f596 | 3296 | schedule_debug(prev); |
1da177e4 | 3297 | |
31656519 | 3298 | if (sched_feat(HRTICK)) |
f333fdc9 | 3299 | hrtick_clear(rq); |
8f4d37ec | 3300 | |
46a5d164 | 3301 | local_irq_disable(); |
bcbfdd01 | 3302 | rcu_note_context_switch(preempt); |
46a5d164 | 3303 | |
e0acd0a6 ON |
3304 | /* |
3305 | * Make sure that signal_pending_state()->signal_pending() below | |
3306 | * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) | |
3307 | * done by the caller to avoid the race with signal_wake_up(). | |
3308 | */ | |
8a8c69c3 | 3309 | rq_lock(rq, &rf); |
d89e588c | 3310 | smp_mb__after_spinlock(); |
1da177e4 | 3311 | |
d1ccc66d IM |
3312 | /* Promote REQ to ACT */ |
3313 | rq->clock_update_flags <<= 1; | |
bce4dc80 | 3314 | update_rq_clock(rq); |
9edfbfed | 3315 | |
246d86b5 | 3316 | switch_count = &prev->nivcsw; |
fc13aeba | 3317 | if (!preempt && prev->state) { |
21aa9af0 | 3318 | if (unlikely(signal_pending_state(prev->state, prev))) { |
1da177e4 | 3319 | prev->state = TASK_RUNNING; |
21aa9af0 | 3320 | } else { |
bce4dc80 | 3321 | deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK); |
2acca55e PZ |
3322 | prev->on_rq = 0; |
3323 | ||
e33a9bba TH |
3324 | if (prev->in_iowait) { |
3325 | atomic_inc(&rq->nr_iowait); | |
3326 | delayacct_blkio_start(); | |
3327 | } | |
3328 | ||
21aa9af0 | 3329 | /* |
2acca55e PZ |
3330 | * If a worker went to sleep, notify and ask workqueue |
3331 | * whether it wants to wake up a task to maintain | |
3332 | * concurrency. | |
21aa9af0 TH |
3333 | */ |
3334 | if (prev->flags & PF_WQ_WORKER) { | |
3335 | struct task_struct *to_wakeup; | |
3336 | ||
9b7f6597 | 3337 | to_wakeup = wq_worker_sleeping(prev); |
21aa9af0 | 3338 | if (to_wakeup) |
d8ac8971 | 3339 | try_to_wake_up_local(to_wakeup, &rf); |
21aa9af0 | 3340 | } |
21aa9af0 | 3341 | } |
dd41f596 | 3342 | switch_count = &prev->nvcsw; |
1da177e4 LT |
3343 | } |
3344 | ||
d8ac8971 | 3345 | next = pick_next_task(rq, prev, &rf); |
f26f9aff | 3346 | clear_tsk_need_resched(prev); |
f27dde8d | 3347 | clear_preempt_need_resched(); |
1da177e4 | 3348 | |
1da177e4 | 3349 | if (likely(prev != next)) { |
1da177e4 LT |
3350 | rq->nr_switches++; |
3351 | rq->curr = next; | |
22e4ebb9 MD |
3352 | /* |
3353 | * The membarrier system call requires each architecture | |
3354 | * to have a full memory barrier after updating | |
3355 | * rq->curr, before returning to user-space. For TSO | |
3356 | * (e.g. x86), the architecture must provide its own | |
3357 | * barrier in switch_mm(). For weakly ordered machines | |
3358 | * for which spin_unlock() acts as a full memory | |
3359 | * barrier, finish_lock_switch() in common code takes | |
3360 | * care of this barrier. For weakly ordered machines for | |
3361 | * which spin_unlock() acts as a RELEASE barrier (only | |
3362 | * arm64 and PowerPC), arm64 has a full barrier in | |
3363 | * switch_to(), and PowerPC has | |
3364 | * smp_mb__after_unlock_lock() before | |
3365 | * finish_lock_switch(). | |
3366 | */ | |
1da177e4 LT |
3367 | ++*switch_count; |
3368 | ||
c73464b1 | 3369 | trace_sched_switch(preempt, prev, next); |
d1ccc66d IM |
3370 | |
3371 | /* Also unlocks the rq: */ | |
3372 | rq = context_switch(rq, prev, next, &rf); | |
cbce1a68 | 3373 | } else { |
cb42c9a3 | 3374 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
8a8c69c3 | 3375 | rq_unlock_irq(rq, &rf); |
cbce1a68 | 3376 | } |
1da177e4 | 3377 | |
e3fca9e7 | 3378 | balance_callback(rq); |
1da177e4 | 3379 | } |
c259e01a | 3380 | |
9af6528e PZ |
3381 | void __noreturn do_task_dead(void) |
3382 | { | |
3383 | /* | |
3384 | * The setting of TASK_RUNNING by try_to_wake_up() may be delayed | |
3385 | * when the following two conditions become true. | |
3386 | * - There is race condition of mmap_sem (It is acquired by | |
3387 | * exit_mm()), and | |
3388 | * - SMI occurs before setting TASK_RUNINNG. | |
3389 | * (or hypervisor of virtual machine switches to other guest) | |
3390 | * As a result, we may become TASK_RUNNING after becoming TASK_DEAD | |
3391 | * | |
3392 | * To avoid it, we have to wait for releasing tsk->pi_lock which | |
3393 | * is held by try_to_wake_up() | |
3394 | */ | |
23a9b748 PM |
3395 | raw_spin_lock_irq(¤t->pi_lock); |
3396 | raw_spin_unlock_irq(¤t->pi_lock); | |
9af6528e | 3397 | |
d1ccc66d | 3398 | /* Causes final put_task_struct in finish_task_switch(): */ |
9af6528e | 3399 | __set_current_state(TASK_DEAD); |
d1ccc66d IM |
3400 | |
3401 | /* Tell freezer to ignore us: */ | |
3402 | current->flags |= PF_NOFREEZE; | |
3403 | ||
9af6528e PZ |
3404 | __schedule(false); |
3405 | BUG(); | |
d1ccc66d IM |
3406 | |
3407 | /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */ | |
9af6528e | 3408 | for (;;) |
d1ccc66d | 3409 | cpu_relax(); |
9af6528e PZ |
3410 | } |
3411 | ||
9c40cef2 TG |
3412 | static inline void sched_submit_work(struct task_struct *tsk) |
3413 | { | |
3c7d5184 | 3414 | if (!tsk->state || tsk_is_pi_blocked(tsk)) |
9c40cef2 TG |
3415 | return; |
3416 | /* | |
3417 | * If we are going to sleep and we have plugged IO queued, | |
3418 | * make sure to submit it to avoid deadlocks. | |
3419 | */ | |
3420 | if (blk_needs_flush_plug(tsk)) | |
3421 | blk_schedule_flush_plug(tsk); | |
3422 | } | |
3423 | ||
722a9f92 | 3424 | asmlinkage __visible void __sched schedule(void) |
c259e01a | 3425 | { |
9c40cef2 TG |
3426 | struct task_struct *tsk = current; |
3427 | ||
3428 | sched_submit_work(tsk); | |
bfd9b2b5 | 3429 | do { |
b30f0e3f | 3430 | preempt_disable(); |
fc13aeba | 3431 | __schedule(false); |
b30f0e3f | 3432 | sched_preempt_enable_no_resched(); |
bfd9b2b5 | 3433 | } while (need_resched()); |
c259e01a | 3434 | } |
1da177e4 LT |
3435 | EXPORT_SYMBOL(schedule); |
3436 | ||
8663effb SRV |
3437 | /* |
3438 | * synchronize_rcu_tasks() makes sure that no task is stuck in preempted | |
3439 | * state (have scheduled out non-voluntarily) by making sure that all | |
3440 | * tasks have either left the run queue or have gone into user space. | |
3441 | * As idle tasks do not do either, they must not ever be preempted | |
3442 | * (schedule out non-voluntarily). | |
3443 | * | |
3444 | * schedule_idle() is similar to schedule_preempt_disable() except that it | |
3445 | * never enables preemption because it does not call sched_submit_work(). | |
3446 | */ | |
3447 | void __sched schedule_idle(void) | |
3448 | { | |
3449 | /* | |
3450 | * As this skips calling sched_submit_work(), which the idle task does | |
3451 | * regardless because that function is a nop when the task is in a | |
3452 | * TASK_RUNNING state, make sure this isn't used someplace that the | |
3453 | * current task can be in any other state. Note, idle is always in the | |
3454 | * TASK_RUNNING state. | |
3455 | */ | |
3456 | WARN_ON_ONCE(current->state); | |
3457 | do { | |
3458 | __schedule(false); | |
3459 | } while (need_resched()); | |
3460 | } | |
3461 | ||
91d1aa43 | 3462 | #ifdef CONFIG_CONTEXT_TRACKING |
722a9f92 | 3463 | asmlinkage __visible void __sched schedule_user(void) |
20ab65e3 FW |
3464 | { |
3465 | /* | |
3466 | * If we come here after a random call to set_need_resched(), | |
3467 | * or we have been woken up remotely but the IPI has not yet arrived, | |
3468 | * we haven't yet exited the RCU idle mode. Do it here manually until | |
3469 | * we find a better solution. | |
7cc78f8f AL |
3470 | * |
3471 | * NB: There are buggy callers of this function. Ideally we | |
c467ea76 | 3472 | * should warn if prev_state != CONTEXT_USER, but that will trigger |
7cc78f8f | 3473 | * too frequently to make sense yet. |
20ab65e3 | 3474 | */ |
7cc78f8f | 3475 | enum ctx_state prev_state = exception_enter(); |
20ab65e3 | 3476 | schedule(); |
7cc78f8f | 3477 | exception_exit(prev_state); |
20ab65e3 FW |
3478 | } |
3479 | #endif | |
3480 | ||
c5491ea7 TG |
3481 | /** |
3482 | * schedule_preempt_disabled - called with preemption disabled | |
3483 | * | |
3484 | * Returns with preemption disabled. Note: preempt_count must be 1 | |
3485 | */ | |
3486 | void __sched schedule_preempt_disabled(void) | |
3487 | { | |
ba74c144 | 3488 | sched_preempt_enable_no_resched(); |
c5491ea7 TG |
3489 | schedule(); |
3490 | preempt_disable(); | |
3491 | } | |
3492 | ||
06b1f808 | 3493 | static void __sched notrace preempt_schedule_common(void) |
a18b5d01 FW |
3494 | { |
3495 | do { | |
47252cfb SR |
3496 | /* |
3497 | * Because the function tracer can trace preempt_count_sub() | |
3498 | * and it also uses preempt_enable/disable_notrace(), if | |
3499 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3500 | * by the function tracer will call this function again and | |
3501 | * cause infinite recursion. | |
3502 | * | |
3503 | * Preemption must be disabled here before the function | |
3504 | * tracer can trace. Break up preempt_disable() into two | |
3505 | * calls. One to disable preemption without fear of being | |
3506 | * traced. The other to still record the preemption latency, | |
3507 | * which can also be traced by the function tracer. | |
3508 | */ | |
499d7955 | 3509 | preempt_disable_notrace(); |
47252cfb | 3510 | preempt_latency_start(1); |
fc13aeba | 3511 | __schedule(true); |
47252cfb | 3512 | preempt_latency_stop(1); |
499d7955 | 3513 | preempt_enable_no_resched_notrace(); |
a18b5d01 FW |
3514 | |
3515 | /* | |
3516 | * Check again in case we missed a preemption opportunity | |
3517 | * between schedule and now. | |
3518 | */ | |
a18b5d01 FW |
3519 | } while (need_resched()); |
3520 | } | |
3521 | ||
1da177e4 LT |
3522 | #ifdef CONFIG_PREEMPT |
3523 | /* | |
2ed6e34f | 3524 | * this is the entry point to schedule() from in-kernel preemption |
41a2d6cf | 3525 | * off of preempt_enable. Kernel preemptions off return from interrupt |
1da177e4 LT |
3526 | * occur there and call schedule directly. |
3527 | */ | |
722a9f92 | 3528 | asmlinkage __visible void __sched notrace preempt_schedule(void) |
1da177e4 | 3529 | { |
1da177e4 LT |
3530 | /* |
3531 | * If there is a non-zero preempt_count or interrupts are disabled, | |
41a2d6cf | 3532 | * we do not want to preempt the current task. Just return.. |
1da177e4 | 3533 | */ |
fbb00b56 | 3534 | if (likely(!preemptible())) |
1da177e4 LT |
3535 | return; |
3536 | ||
a18b5d01 | 3537 | preempt_schedule_common(); |
1da177e4 | 3538 | } |
376e2424 | 3539 | NOKPROBE_SYMBOL(preempt_schedule); |
1da177e4 | 3540 | EXPORT_SYMBOL(preempt_schedule); |
009f60e2 | 3541 | |
009f60e2 | 3542 | /** |
4eaca0a8 | 3543 | * preempt_schedule_notrace - preempt_schedule called by tracing |
009f60e2 ON |
3544 | * |
3545 | * The tracing infrastructure uses preempt_enable_notrace to prevent | |
3546 | * recursion and tracing preempt enabling caused by the tracing | |
3547 | * infrastructure itself. But as tracing can happen in areas coming | |
3548 | * from userspace or just about to enter userspace, a preempt enable | |
3549 | * can occur before user_exit() is called. This will cause the scheduler | |
3550 | * to be called when the system is still in usermode. | |
3551 | * | |
3552 | * To prevent this, the preempt_enable_notrace will use this function | |
3553 | * instead of preempt_schedule() to exit user context if needed before | |
3554 | * calling the scheduler. | |
3555 | */ | |
4eaca0a8 | 3556 | asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) |
009f60e2 ON |
3557 | { |
3558 | enum ctx_state prev_ctx; | |
3559 | ||
3560 | if (likely(!preemptible())) | |
3561 | return; | |
3562 | ||
3563 | do { | |
47252cfb SR |
3564 | /* |
3565 | * Because the function tracer can trace preempt_count_sub() | |
3566 | * and it also uses preempt_enable/disable_notrace(), if | |
3567 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3568 | * by the function tracer will call this function again and | |
3569 | * cause infinite recursion. | |
3570 | * | |
3571 | * Preemption must be disabled here before the function | |
3572 | * tracer can trace. Break up preempt_disable() into two | |
3573 | * calls. One to disable preemption without fear of being | |
3574 | * traced. The other to still record the preemption latency, | |
3575 | * which can also be traced by the function tracer. | |
3576 | */ | |
3d8f74dd | 3577 | preempt_disable_notrace(); |
47252cfb | 3578 | preempt_latency_start(1); |
009f60e2 ON |
3579 | /* |
3580 | * Needs preempt disabled in case user_exit() is traced | |
3581 | * and the tracer calls preempt_enable_notrace() causing | |
3582 | * an infinite recursion. | |
3583 | */ | |
3584 | prev_ctx = exception_enter(); | |
fc13aeba | 3585 | __schedule(true); |
009f60e2 ON |
3586 | exception_exit(prev_ctx); |
3587 | ||
47252cfb | 3588 | preempt_latency_stop(1); |
3d8f74dd | 3589 | preempt_enable_no_resched_notrace(); |
009f60e2 ON |
3590 | } while (need_resched()); |
3591 | } | |
4eaca0a8 | 3592 | EXPORT_SYMBOL_GPL(preempt_schedule_notrace); |
009f60e2 | 3593 | |
32e475d7 | 3594 | #endif /* CONFIG_PREEMPT */ |
1da177e4 LT |
3595 | |
3596 | /* | |
2ed6e34f | 3597 | * this is the entry point to schedule() from kernel preemption |
1da177e4 LT |
3598 | * off of irq context. |
3599 | * Note, that this is called and return with irqs disabled. This will | |
3600 | * protect us against recursive calling from irq. | |
3601 | */ | |
722a9f92 | 3602 | asmlinkage __visible void __sched preempt_schedule_irq(void) |
1da177e4 | 3603 | { |
b22366cd | 3604 | enum ctx_state prev_state; |
6478d880 | 3605 | |
2ed6e34f | 3606 | /* Catch callers which need to be fixed */ |
f27dde8d | 3607 | BUG_ON(preempt_count() || !irqs_disabled()); |
1da177e4 | 3608 | |
b22366cd FW |
3609 | prev_state = exception_enter(); |
3610 | ||
3a5c359a | 3611 | do { |
3d8f74dd | 3612 | preempt_disable(); |
3a5c359a | 3613 | local_irq_enable(); |
fc13aeba | 3614 | __schedule(true); |
3a5c359a | 3615 | local_irq_disable(); |
3d8f74dd | 3616 | sched_preempt_enable_no_resched(); |
5ed0cec0 | 3617 | } while (need_resched()); |
b22366cd FW |
3618 | |
3619 | exception_exit(prev_state); | |
1da177e4 LT |
3620 | } |
3621 | ||
ac6424b9 | 3622 | int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags, |
95cdf3b7 | 3623 | void *key) |
1da177e4 | 3624 | { |
63859d4f | 3625 | return try_to_wake_up(curr->private, mode, wake_flags); |
1da177e4 | 3626 | } |
1da177e4 LT |
3627 | EXPORT_SYMBOL(default_wake_function); |
3628 | ||
b29739f9 IM |
3629 | #ifdef CONFIG_RT_MUTEXES |
3630 | ||
acd58620 PZ |
3631 | static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) |
3632 | { | |
3633 | if (pi_task) | |
3634 | prio = min(prio, pi_task->prio); | |
3635 | ||
3636 | return prio; | |
3637 | } | |
3638 | ||
3639 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3640 | { | |
3641 | struct task_struct *pi_task = rt_mutex_get_top_task(p); | |
3642 | ||
3643 | return __rt_effective_prio(pi_task, prio); | |
3644 | } | |
3645 | ||
b29739f9 IM |
3646 | /* |
3647 | * rt_mutex_setprio - set the current priority of a task | |
acd58620 PZ |
3648 | * @p: task to boost |
3649 | * @pi_task: donor task | |
b29739f9 IM |
3650 | * |
3651 | * This function changes the 'effective' priority of a task. It does | |
3652 | * not touch ->normal_prio like __setscheduler(). | |
3653 | * | |
c365c292 TG |
3654 | * Used by the rt_mutex code to implement priority inheritance |
3655 | * logic. Call site only calls if the priority of the task changed. | |
b29739f9 | 3656 | */ |
acd58620 | 3657 | void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) |
b29739f9 | 3658 | { |
acd58620 | 3659 | int prio, oldprio, queued, running, queue_flag = |
7a57f32a | 3660 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
83ab0aa0 | 3661 | const struct sched_class *prev_class; |
eb580751 PZ |
3662 | struct rq_flags rf; |
3663 | struct rq *rq; | |
b29739f9 | 3664 | |
acd58620 PZ |
3665 | /* XXX used to be waiter->prio, not waiter->task->prio */ |
3666 | prio = __rt_effective_prio(pi_task, p->normal_prio); | |
3667 | ||
3668 | /* | |
3669 | * If nothing changed; bail early. | |
3670 | */ | |
3671 | if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio)) | |
3672 | return; | |
b29739f9 | 3673 | |
eb580751 | 3674 | rq = __task_rq_lock(p, &rf); |
80f5c1b8 | 3675 | update_rq_clock(rq); |
acd58620 PZ |
3676 | /* |
3677 | * Set under pi_lock && rq->lock, such that the value can be used under | |
3678 | * either lock. | |
3679 | * | |
3680 | * Note that there is loads of tricky to make this pointer cache work | |
3681 | * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to | |
3682 | * ensure a task is de-boosted (pi_task is set to NULL) before the | |
3683 | * task is allowed to run again (and can exit). This ensures the pointer | |
3684 | * points to a blocked task -- which guaratees the task is present. | |
3685 | */ | |
3686 | p->pi_top_task = pi_task; | |
3687 | ||
3688 | /* | |
3689 | * For FIFO/RR we only need to set prio, if that matches we're done. | |
3690 | */ | |
3691 | if (prio == p->prio && !dl_prio(prio)) | |
3692 | goto out_unlock; | |
b29739f9 | 3693 | |
1c4dd99b TG |
3694 | /* |
3695 | * Idle task boosting is a nono in general. There is one | |
3696 | * exception, when PREEMPT_RT and NOHZ is active: | |
3697 | * | |
3698 | * The idle task calls get_next_timer_interrupt() and holds | |
3699 | * the timer wheel base->lock on the CPU and another CPU wants | |
3700 | * to access the timer (probably to cancel it). We can safely | |
3701 | * ignore the boosting request, as the idle CPU runs this code | |
3702 | * with interrupts disabled and will complete the lock | |
3703 | * protected section without being interrupted. So there is no | |
3704 | * real need to boost. | |
3705 | */ | |
3706 | if (unlikely(p == rq->idle)) { | |
3707 | WARN_ON(p != rq->curr); | |
3708 | WARN_ON(p->pi_blocked_on); | |
3709 | goto out_unlock; | |
3710 | } | |
3711 | ||
b91473ff | 3712 | trace_sched_pi_setprio(p, pi_task); |
d5f9f942 | 3713 | oldprio = p->prio; |
ff77e468 PZ |
3714 | |
3715 | if (oldprio == prio) | |
3716 | queue_flag &= ~DEQUEUE_MOVE; | |
3717 | ||
83ab0aa0 | 3718 | prev_class = p->sched_class; |
da0c1e65 | 3719 | queued = task_on_rq_queued(p); |
051a1d1a | 3720 | running = task_current(rq, p); |
da0c1e65 | 3721 | if (queued) |
ff77e468 | 3722 | dequeue_task(rq, p, queue_flag); |
0e1f3483 | 3723 | if (running) |
f3cd1c4e | 3724 | put_prev_task(rq, p); |
dd41f596 | 3725 | |
2d3d891d DF |
3726 | /* |
3727 | * Boosting condition are: | |
3728 | * 1. -rt task is running and holds mutex A | |
3729 | * --> -dl task blocks on mutex A | |
3730 | * | |
3731 | * 2. -dl task is running and holds mutex A | |
3732 | * --> -dl task blocks on mutex A and could preempt the | |
3733 | * running task | |
3734 | */ | |
3735 | if (dl_prio(prio)) { | |
466af29b ON |
3736 | if (!dl_prio(p->normal_prio) || |
3737 | (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { | |
2d3d891d | 3738 | p->dl.dl_boosted = 1; |
ff77e468 | 3739 | queue_flag |= ENQUEUE_REPLENISH; |
2d3d891d DF |
3740 | } else |
3741 | p->dl.dl_boosted = 0; | |
aab03e05 | 3742 | p->sched_class = &dl_sched_class; |
2d3d891d DF |
3743 | } else if (rt_prio(prio)) { |
3744 | if (dl_prio(oldprio)) | |
3745 | p->dl.dl_boosted = 0; | |
3746 | if (oldprio < prio) | |
ff77e468 | 3747 | queue_flag |= ENQUEUE_HEAD; |
dd41f596 | 3748 | p->sched_class = &rt_sched_class; |
2d3d891d DF |
3749 | } else { |
3750 | if (dl_prio(oldprio)) | |
3751 | p->dl.dl_boosted = 0; | |
746db944 BS |
3752 | if (rt_prio(oldprio)) |
3753 | p->rt.timeout = 0; | |
dd41f596 | 3754 | p->sched_class = &fair_sched_class; |
2d3d891d | 3755 | } |
dd41f596 | 3756 | |
b29739f9 IM |
3757 | p->prio = prio; |
3758 | ||
da0c1e65 | 3759 | if (queued) |
ff77e468 | 3760 | enqueue_task(rq, p, queue_flag); |
a399d233 | 3761 | if (running) |
b2bf6c31 | 3762 | set_curr_task(rq, p); |
cb469845 | 3763 | |
da7a735e | 3764 | check_class_changed(rq, p, prev_class, oldprio); |
1c4dd99b | 3765 | out_unlock: |
d1ccc66d IM |
3766 | /* Avoid rq from going away on us: */ |
3767 | preempt_disable(); | |
eb580751 | 3768 | __task_rq_unlock(rq, &rf); |
4c9a4bc8 PZ |
3769 | |
3770 | balance_callback(rq); | |
3771 | preempt_enable(); | |
b29739f9 | 3772 | } |
acd58620 PZ |
3773 | #else |
3774 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3775 | { | |
3776 | return prio; | |
3777 | } | |
b29739f9 | 3778 | #endif |
d50dde5a | 3779 | |
36c8b586 | 3780 | void set_user_nice(struct task_struct *p, long nice) |
1da177e4 | 3781 | { |
49bd21ef PZ |
3782 | bool queued, running; |
3783 | int old_prio, delta; | |
eb580751 | 3784 | struct rq_flags rf; |
70b97a7f | 3785 | struct rq *rq; |
1da177e4 | 3786 | |
75e45d51 | 3787 | if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) |
1da177e4 LT |
3788 | return; |
3789 | /* | |
3790 | * We have to be careful, if called from sys_setpriority(), | |
3791 | * the task might be in the middle of scheduling on another CPU. | |
3792 | */ | |
eb580751 | 3793 | rq = task_rq_lock(p, &rf); |
2fb8d367 PZ |
3794 | update_rq_clock(rq); |
3795 | ||
1da177e4 LT |
3796 | /* |
3797 | * The RT priorities are set via sched_setscheduler(), but we still | |
3798 | * allow the 'normal' nice value to be set - but as expected | |
3799 | * it wont have any effect on scheduling until the task is | |
aab03e05 | 3800 | * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: |
1da177e4 | 3801 | */ |
aab03e05 | 3802 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
1da177e4 LT |
3803 | p->static_prio = NICE_TO_PRIO(nice); |
3804 | goto out_unlock; | |
3805 | } | |
da0c1e65 | 3806 | queued = task_on_rq_queued(p); |
49bd21ef | 3807 | running = task_current(rq, p); |
da0c1e65 | 3808 | if (queued) |
7a57f32a | 3809 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
49bd21ef PZ |
3810 | if (running) |
3811 | put_prev_task(rq, p); | |
1da177e4 | 3812 | |
1da177e4 | 3813 | p->static_prio = NICE_TO_PRIO(nice); |
9059393e | 3814 | set_load_weight(p, true); |
b29739f9 IM |
3815 | old_prio = p->prio; |
3816 | p->prio = effective_prio(p); | |
3817 | delta = p->prio - old_prio; | |
1da177e4 | 3818 | |
da0c1e65 | 3819 | if (queued) { |
7134b3e9 | 3820 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
1da177e4 | 3821 | /* |
d5f9f942 AM |
3822 | * If the task increased its priority or is running and |
3823 | * lowered its priority, then reschedule its CPU: | |
1da177e4 | 3824 | */ |
d5f9f942 | 3825 | if (delta < 0 || (delta > 0 && task_running(rq, p))) |
8875125e | 3826 | resched_curr(rq); |
1da177e4 | 3827 | } |
49bd21ef PZ |
3828 | if (running) |
3829 | set_curr_task(rq, p); | |
1da177e4 | 3830 | out_unlock: |
eb580751 | 3831 | task_rq_unlock(rq, p, &rf); |
1da177e4 | 3832 | } |
1da177e4 LT |
3833 | EXPORT_SYMBOL(set_user_nice); |
3834 | ||
e43379f1 MM |
3835 | /* |
3836 | * can_nice - check if a task can reduce its nice value | |
3837 | * @p: task | |
3838 | * @nice: nice value | |
3839 | */ | |
36c8b586 | 3840 | int can_nice(const struct task_struct *p, const int nice) |
e43379f1 | 3841 | { |
d1ccc66d | 3842 | /* Convert nice value [19,-20] to rlimit style value [1,40]: */ |
7aa2c016 | 3843 | int nice_rlim = nice_to_rlimit(nice); |
48f24c4d | 3844 | |
78d7d407 | 3845 | return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || |
e43379f1 MM |
3846 | capable(CAP_SYS_NICE)); |
3847 | } | |
3848 | ||
1da177e4 LT |
3849 | #ifdef __ARCH_WANT_SYS_NICE |
3850 | ||
3851 | /* | |
3852 | * sys_nice - change the priority of the current process. | |
3853 | * @increment: priority increment | |
3854 | * | |
3855 | * sys_setpriority is a more generic, but much slower function that | |
3856 | * does similar things. | |
3857 | */ | |
5add95d4 | 3858 | SYSCALL_DEFINE1(nice, int, increment) |
1da177e4 | 3859 | { |
48f24c4d | 3860 | long nice, retval; |
1da177e4 LT |
3861 | |
3862 | /* | |
3863 | * Setpriority might change our priority at the same moment. | |
3864 | * We don't have to worry. Conceptually one call occurs first | |
3865 | * and we have a single winner. | |
3866 | */ | |
a9467fa3 | 3867 | increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); |
d0ea0268 | 3868 | nice = task_nice(current) + increment; |
1da177e4 | 3869 | |
a9467fa3 | 3870 | nice = clamp_val(nice, MIN_NICE, MAX_NICE); |
e43379f1 MM |
3871 | if (increment < 0 && !can_nice(current, nice)) |
3872 | return -EPERM; | |
3873 | ||
1da177e4 LT |
3874 | retval = security_task_setnice(current, nice); |
3875 | if (retval) | |
3876 | return retval; | |
3877 | ||
3878 | set_user_nice(current, nice); | |
3879 | return 0; | |
3880 | } | |
3881 | ||
3882 | #endif | |
3883 | ||
3884 | /** | |
3885 | * task_prio - return the priority value of a given task. | |
3886 | * @p: the task in question. | |
3887 | * | |
e69f6186 | 3888 | * Return: The priority value as seen by users in /proc. |
1da177e4 LT |
3889 | * RT tasks are offset by -200. Normal tasks are centered |
3890 | * around 0, value goes from -16 to +15. | |
3891 | */ | |
36c8b586 | 3892 | int task_prio(const struct task_struct *p) |
1da177e4 LT |
3893 | { |
3894 | return p->prio - MAX_RT_PRIO; | |
3895 | } | |
3896 | ||
1da177e4 | 3897 | /** |
d1ccc66d | 3898 | * idle_cpu - is a given CPU idle currently? |
1da177e4 | 3899 | * @cpu: the processor in question. |
e69f6186 YB |
3900 | * |
3901 | * Return: 1 if the CPU is currently idle. 0 otherwise. | |
1da177e4 LT |
3902 | */ |
3903 | int idle_cpu(int cpu) | |
3904 | { | |
908a3283 TG |
3905 | struct rq *rq = cpu_rq(cpu); |
3906 | ||
3907 | if (rq->curr != rq->idle) | |
3908 | return 0; | |
3909 | ||
3910 | if (rq->nr_running) | |
3911 | return 0; | |
3912 | ||
3913 | #ifdef CONFIG_SMP | |
3914 | if (!llist_empty(&rq->wake_list)) | |
3915 | return 0; | |
3916 | #endif | |
3917 | ||
3918 | return 1; | |
1da177e4 LT |
3919 | } |
3920 | ||
1da177e4 | 3921 | /** |
d1ccc66d | 3922 | * idle_task - return the idle task for a given CPU. |
1da177e4 | 3923 | * @cpu: the processor in question. |
e69f6186 | 3924 | * |
d1ccc66d | 3925 | * Return: The idle task for the CPU @cpu. |
1da177e4 | 3926 | */ |
36c8b586 | 3927 | struct task_struct *idle_task(int cpu) |
1da177e4 LT |
3928 | { |
3929 | return cpu_rq(cpu)->idle; | |
3930 | } | |
3931 | ||
3932 | /** | |
3933 | * find_process_by_pid - find a process with a matching PID value. | |
3934 | * @pid: the pid in question. | |
e69f6186 YB |
3935 | * |
3936 | * The task of @pid, if found. %NULL otherwise. | |
1da177e4 | 3937 | */ |
a9957449 | 3938 | static struct task_struct *find_process_by_pid(pid_t pid) |
1da177e4 | 3939 | { |
228ebcbe | 3940 | return pid ? find_task_by_vpid(pid) : current; |
1da177e4 LT |
3941 | } |
3942 | ||
c13db6b1 SR |
3943 | /* |
3944 | * sched_setparam() passes in -1 for its policy, to let the functions | |
3945 | * it calls know not to change it. | |
3946 | */ | |
3947 | #define SETPARAM_POLICY -1 | |
3948 | ||
c365c292 TG |
3949 | static void __setscheduler_params(struct task_struct *p, |
3950 | const struct sched_attr *attr) | |
1da177e4 | 3951 | { |
d50dde5a DF |
3952 | int policy = attr->sched_policy; |
3953 | ||
c13db6b1 | 3954 | if (policy == SETPARAM_POLICY) |
39fd8fd2 PZ |
3955 | policy = p->policy; |
3956 | ||
1da177e4 | 3957 | p->policy = policy; |
d50dde5a | 3958 | |
aab03e05 DF |
3959 | if (dl_policy(policy)) |
3960 | __setparam_dl(p, attr); | |
39fd8fd2 | 3961 | else if (fair_policy(policy)) |
d50dde5a DF |
3962 | p->static_prio = NICE_TO_PRIO(attr->sched_nice); |
3963 | ||
39fd8fd2 PZ |
3964 | /* |
3965 | * __sched_setscheduler() ensures attr->sched_priority == 0 when | |
3966 | * !rt_policy. Always setting this ensures that things like | |
3967 | * getparam()/getattr() don't report silly values for !rt tasks. | |
3968 | */ | |
3969 | p->rt_priority = attr->sched_priority; | |
383afd09 | 3970 | p->normal_prio = normal_prio(p); |
9059393e | 3971 | set_load_weight(p, true); |
c365c292 | 3972 | } |
39fd8fd2 | 3973 | |
c365c292 TG |
3974 | /* Actually do priority change: must hold pi & rq lock. */ |
3975 | static void __setscheduler(struct rq *rq, struct task_struct *p, | |
0782e63b | 3976 | const struct sched_attr *attr, bool keep_boost) |
c365c292 TG |
3977 | { |
3978 | __setscheduler_params(p, attr); | |
d50dde5a | 3979 | |
383afd09 | 3980 | /* |
0782e63b TG |
3981 | * Keep a potential priority boosting if called from |
3982 | * sched_setscheduler(). | |
383afd09 | 3983 | */ |
acd58620 | 3984 | p->prio = normal_prio(p); |
0782e63b | 3985 | if (keep_boost) |
acd58620 | 3986 | p->prio = rt_effective_prio(p, p->prio); |
383afd09 | 3987 | |
aab03e05 DF |
3988 | if (dl_prio(p->prio)) |
3989 | p->sched_class = &dl_sched_class; | |
3990 | else if (rt_prio(p->prio)) | |
ffd44db5 PZ |
3991 | p->sched_class = &rt_sched_class; |
3992 | else | |
3993 | p->sched_class = &fair_sched_class; | |
1da177e4 | 3994 | } |
aab03e05 | 3995 | |
c69e8d9c | 3996 | /* |
d1ccc66d | 3997 | * Check the target process has a UID that matches the current process's: |
c69e8d9c DH |
3998 | */ |
3999 | static bool check_same_owner(struct task_struct *p) | |
4000 | { | |
4001 | const struct cred *cred = current_cred(), *pcred; | |
4002 | bool match; | |
4003 | ||
4004 | rcu_read_lock(); | |
4005 | pcred = __task_cred(p); | |
9c806aa0 EB |
4006 | match = (uid_eq(cred->euid, pcred->euid) || |
4007 | uid_eq(cred->euid, pcred->uid)); | |
c69e8d9c DH |
4008 | rcu_read_unlock(); |
4009 | return match; | |
4010 | } | |
4011 | ||
d50dde5a DF |
4012 | static int __sched_setscheduler(struct task_struct *p, |
4013 | const struct sched_attr *attr, | |
dbc7f069 | 4014 | bool user, bool pi) |
1da177e4 | 4015 | { |
383afd09 SR |
4016 | int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : |
4017 | MAX_RT_PRIO - 1 - attr->sched_priority; | |
da0c1e65 | 4018 | int retval, oldprio, oldpolicy = -1, queued, running; |
0782e63b | 4019 | int new_effective_prio, policy = attr->sched_policy; |
83ab0aa0 | 4020 | const struct sched_class *prev_class; |
eb580751 | 4021 | struct rq_flags rf; |
ca94c442 | 4022 | int reset_on_fork; |
7a57f32a | 4023 | int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
eb580751 | 4024 | struct rq *rq; |
1da177e4 | 4025 | |
896bbb25 SRV |
4026 | /* The pi code expects interrupts enabled */ |
4027 | BUG_ON(pi && in_interrupt()); | |
1da177e4 | 4028 | recheck: |
d1ccc66d | 4029 | /* Double check policy once rq lock held: */ |
ca94c442 LP |
4030 | if (policy < 0) { |
4031 | reset_on_fork = p->sched_reset_on_fork; | |
1da177e4 | 4032 | policy = oldpolicy = p->policy; |
ca94c442 | 4033 | } else { |
7479f3c9 | 4034 | reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); |
ca94c442 | 4035 | |
20f9cd2a | 4036 | if (!valid_policy(policy)) |
ca94c442 LP |
4037 | return -EINVAL; |
4038 | } | |
4039 | ||
2d4283e9 LA |
4040 | if (attr->sched_flags & |
4041 | ~(SCHED_FLAG_RESET_ON_FORK | SCHED_FLAG_RECLAIM)) | |
7479f3c9 PZ |
4042 | return -EINVAL; |
4043 | ||
1da177e4 LT |
4044 | /* |
4045 | * Valid priorities for SCHED_FIFO and SCHED_RR are | |
dd41f596 IM |
4046 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, |
4047 | * SCHED_BATCH and SCHED_IDLE is 0. | |
1da177e4 | 4048 | */ |
0bb040a4 | 4049 | if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || |
d50dde5a | 4050 | (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) |
1da177e4 | 4051 | return -EINVAL; |
aab03e05 DF |
4052 | if ((dl_policy(policy) && !__checkparam_dl(attr)) || |
4053 | (rt_policy(policy) != (attr->sched_priority != 0))) | |
1da177e4 LT |
4054 | return -EINVAL; |
4055 | ||
37e4ab3f OC |
4056 | /* |
4057 | * Allow unprivileged RT tasks to decrease priority: | |
4058 | */ | |
961ccddd | 4059 | if (user && !capable(CAP_SYS_NICE)) { |
d50dde5a | 4060 | if (fair_policy(policy)) { |
d0ea0268 | 4061 | if (attr->sched_nice < task_nice(p) && |
eaad4513 | 4062 | !can_nice(p, attr->sched_nice)) |
d50dde5a DF |
4063 | return -EPERM; |
4064 | } | |
4065 | ||
e05606d3 | 4066 | if (rt_policy(policy)) { |
a44702e8 ON |
4067 | unsigned long rlim_rtprio = |
4068 | task_rlimit(p, RLIMIT_RTPRIO); | |
8dc3e909 | 4069 | |
d1ccc66d | 4070 | /* Can't set/change the rt policy: */ |
8dc3e909 ON |
4071 | if (policy != p->policy && !rlim_rtprio) |
4072 | return -EPERM; | |
4073 | ||
d1ccc66d | 4074 | /* Can't increase priority: */ |
d50dde5a DF |
4075 | if (attr->sched_priority > p->rt_priority && |
4076 | attr->sched_priority > rlim_rtprio) | |
8dc3e909 ON |
4077 | return -EPERM; |
4078 | } | |
c02aa73b | 4079 | |
d44753b8 JL |
4080 | /* |
4081 | * Can't set/change SCHED_DEADLINE policy at all for now | |
4082 | * (safest behavior); in the future we would like to allow | |
4083 | * unprivileged DL tasks to increase their relative deadline | |
4084 | * or reduce their runtime (both ways reducing utilization) | |
4085 | */ | |
4086 | if (dl_policy(policy)) | |
4087 | return -EPERM; | |
4088 | ||
dd41f596 | 4089 | /* |
c02aa73b DH |
4090 | * Treat SCHED_IDLE as nice 20. Only allow a switch to |
4091 | * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. | |
dd41f596 | 4092 | */ |
20f9cd2a | 4093 | if (idle_policy(p->policy) && !idle_policy(policy)) { |
d0ea0268 | 4094 | if (!can_nice(p, task_nice(p))) |
c02aa73b DH |
4095 | return -EPERM; |
4096 | } | |
5fe1d75f | 4097 | |
d1ccc66d | 4098 | /* Can't change other user's priorities: */ |
c69e8d9c | 4099 | if (!check_same_owner(p)) |
37e4ab3f | 4100 | return -EPERM; |
ca94c442 | 4101 | |
d1ccc66d | 4102 | /* Normal users shall not reset the sched_reset_on_fork flag: */ |
ca94c442 LP |
4103 | if (p->sched_reset_on_fork && !reset_on_fork) |
4104 | return -EPERM; | |
37e4ab3f | 4105 | } |
1da177e4 | 4106 | |
725aad24 | 4107 | if (user) { |
b0ae1981 | 4108 | retval = security_task_setscheduler(p); |
725aad24 JF |
4109 | if (retval) |
4110 | return retval; | |
4111 | } | |
4112 | ||
b29739f9 | 4113 | /* |
d1ccc66d | 4114 | * Make sure no PI-waiters arrive (or leave) while we are |
b29739f9 | 4115 | * changing the priority of the task: |
0122ec5b | 4116 | * |
25985edc | 4117 | * To be able to change p->policy safely, the appropriate |
1da177e4 LT |
4118 | * runqueue lock must be held. |
4119 | */ | |
eb580751 | 4120 | rq = task_rq_lock(p, &rf); |
80f5c1b8 | 4121 | update_rq_clock(rq); |
dc61b1d6 | 4122 | |
34f971f6 | 4123 | /* |
d1ccc66d | 4124 | * Changing the policy of the stop threads its a very bad idea: |
34f971f6 PZ |
4125 | */ |
4126 | if (p == rq->stop) { | |
eb580751 | 4127 | task_rq_unlock(rq, p, &rf); |
34f971f6 PZ |
4128 | return -EINVAL; |
4129 | } | |
4130 | ||
a51e9198 | 4131 | /* |
d6b1e911 TG |
4132 | * If not changing anything there's no need to proceed further, |
4133 | * but store a possible modification of reset_on_fork. | |
a51e9198 | 4134 | */ |
d50dde5a | 4135 | if (unlikely(policy == p->policy)) { |
d0ea0268 | 4136 | if (fair_policy(policy) && attr->sched_nice != task_nice(p)) |
d50dde5a DF |
4137 | goto change; |
4138 | if (rt_policy(policy) && attr->sched_priority != p->rt_priority) | |
4139 | goto change; | |
75381608 | 4140 | if (dl_policy(policy) && dl_param_changed(p, attr)) |
aab03e05 | 4141 | goto change; |
d50dde5a | 4142 | |
d6b1e911 | 4143 | p->sched_reset_on_fork = reset_on_fork; |
eb580751 | 4144 | task_rq_unlock(rq, p, &rf); |
a51e9198 DF |
4145 | return 0; |
4146 | } | |
d50dde5a | 4147 | change: |
a51e9198 | 4148 | |
dc61b1d6 | 4149 | if (user) { |
332ac17e | 4150 | #ifdef CONFIG_RT_GROUP_SCHED |
dc61b1d6 PZ |
4151 | /* |
4152 | * Do not allow realtime tasks into groups that have no runtime | |
4153 | * assigned. | |
4154 | */ | |
4155 | if (rt_bandwidth_enabled() && rt_policy(policy) && | |
f4493771 MG |
4156 | task_group(p)->rt_bandwidth.rt_runtime == 0 && |
4157 | !task_group_is_autogroup(task_group(p))) { | |
eb580751 | 4158 | task_rq_unlock(rq, p, &rf); |
dc61b1d6 PZ |
4159 | return -EPERM; |
4160 | } | |
dc61b1d6 | 4161 | #endif |
332ac17e DF |
4162 | #ifdef CONFIG_SMP |
4163 | if (dl_bandwidth_enabled() && dl_policy(policy)) { | |
4164 | cpumask_t *span = rq->rd->span; | |
332ac17e DF |
4165 | |
4166 | /* | |
4167 | * Don't allow tasks with an affinity mask smaller than | |
4168 | * the entire root_domain to become SCHED_DEADLINE. We | |
4169 | * will also fail if there's no bandwidth available. | |
4170 | */ | |
e4099a5e PZ |
4171 | if (!cpumask_subset(span, &p->cpus_allowed) || |
4172 | rq->rd->dl_bw.bw == 0) { | |
eb580751 | 4173 | task_rq_unlock(rq, p, &rf); |
332ac17e DF |
4174 | return -EPERM; |
4175 | } | |
4176 | } | |
4177 | #endif | |
4178 | } | |
dc61b1d6 | 4179 | |
d1ccc66d | 4180 | /* Re-check policy now with rq lock held: */ |
1da177e4 LT |
4181 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { |
4182 | policy = oldpolicy = -1; | |
eb580751 | 4183 | task_rq_unlock(rq, p, &rf); |
1da177e4 LT |
4184 | goto recheck; |
4185 | } | |
332ac17e DF |
4186 | |
4187 | /* | |
4188 | * If setscheduling to SCHED_DEADLINE (or changing the parameters | |
4189 | * of a SCHED_DEADLINE task) we need to check if enough bandwidth | |
4190 | * is available. | |
4191 | */ | |
06a76fe0 | 4192 | if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) { |
eb580751 | 4193 | task_rq_unlock(rq, p, &rf); |
332ac17e DF |
4194 | return -EBUSY; |
4195 | } | |
4196 | ||
c365c292 TG |
4197 | p->sched_reset_on_fork = reset_on_fork; |
4198 | oldprio = p->prio; | |
4199 | ||
dbc7f069 PZ |
4200 | if (pi) { |
4201 | /* | |
4202 | * Take priority boosted tasks into account. If the new | |
4203 | * effective priority is unchanged, we just store the new | |
4204 | * normal parameters and do not touch the scheduler class and | |
4205 | * the runqueue. This will be done when the task deboost | |
4206 | * itself. | |
4207 | */ | |
acd58620 | 4208 | new_effective_prio = rt_effective_prio(p, newprio); |
ff77e468 PZ |
4209 | if (new_effective_prio == oldprio) |
4210 | queue_flags &= ~DEQUEUE_MOVE; | |
c365c292 TG |
4211 | } |
4212 | ||
da0c1e65 | 4213 | queued = task_on_rq_queued(p); |
051a1d1a | 4214 | running = task_current(rq, p); |
da0c1e65 | 4215 | if (queued) |
ff77e468 | 4216 | dequeue_task(rq, p, queue_flags); |
0e1f3483 | 4217 | if (running) |
f3cd1c4e | 4218 | put_prev_task(rq, p); |
f6b53205 | 4219 | |
83ab0aa0 | 4220 | prev_class = p->sched_class; |
dbc7f069 | 4221 | __setscheduler(rq, p, attr, pi); |
f6b53205 | 4222 | |
da0c1e65 | 4223 | if (queued) { |
81a44c54 TG |
4224 | /* |
4225 | * We enqueue to tail when the priority of a task is | |
4226 | * increased (user space view). | |
4227 | */ | |
ff77e468 PZ |
4228 | if (oldprio < p->prio) |
4229 | queue_flags |= ENQUEUE_HEAD; | |
1de64443 | 4230 | |
ff77e468 | 4231 | enqueue_task(rq, p, queue_flags); |
81a44c54 | 4232 | } |
a399d233 | 4233 | if (running) |
b2bf6c31 | 4234 | set_curr_task(rq, p); |
cb469845 | 4235 | |
da7a735e | 4236 | check_class_changed(rq, p, prev_class, oldprio); |
d1ccc66d IM |
4237 | |
4238 | /* Avoid rq from going away on us: */ | |
4239 | preempt_disable(); | |
eb580751 | 4240 | task_rq_unlock(rq, p, &rf); |
b29739f9 | 4241 | |
dbc7f069 PZ |
4242 | if (pi) |
4243 | rt_mutex_adjust_pi(p); | |
95e02ca9 | 4244 | |
d1ccc66d | 4245 | /* Run balance callbacks after we've adjusted the PI chain: */ |
4c9a4bc8 PZ |
4246 | balance_callback(rq); |
4247 | preempt_enable(); | |
95e02ca9 | 4248 | |
1da177e4 LT |
4249 | return 0; |
4250 | } | |
961ccddd | 4251 | |
7479f3c9 PZ |
4252 | static int _sched_setscheduler(struct task_struct *p, int policy, |
4253 | const struct sched_param *param, bool check) | |
4254 | { | |
4255 | struct sched_attr attr = { | |
4256 | .sched_policy = policy, | |
4257 | .sched_priority = param->sched_priority, | |
4258 | .sched_nice = PRIO_TO_NICE(p->static_prio), | |
4259 | }; | |
4260 | ||
c13db6b1 SR |
4261 | /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ |
4262 | if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { | |
7479f3c9 PZ |
4263 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
4264 | policy &= ~SCHED_RESET_ON_FORK; | |
4265 | attr.sched_policy = policy; | |
4266 | } | |
4267 | ||
dbc7f069 | 4268 | return __sched_setscheduler(p, &attr, check, true); |
7479f3c9 | 4269 | } |
961ccddd RR |
4270 | /** |
4271 | * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. | |
4272 | * @p: the task in question. | |
4273 | * @policy: new policy. | |
4274 | * @param: structure containing the new RT priority. | |
4275 | * | |
e69f6186 YB |
4276 | * Return: 0 on success. An error code otherwise. |
4277 | * | |
961ccddd RR |
4278 | * NOTE that the task may be already dead. |
4279 | */ | |
4280 | int sched_setscheduler(struct task_struct *p, int policy, | |
fe7de49f | 4281 | const struct sched_param *param) |
961ccddd | 4282 | { |
7479f3c9 | 4283 | return _sched_setscheduler(p, policy, param, true); |
961ccddd | 4284 | } |
1da177e4 LT |
4285 | EXPORT_SYMBOL_GPL(sched_setscheduler); |
4286 | ||
d50dde5a DF |
4287 | int sched_setattr(struct task_struct *p, const struct sched_attr *attr) |
4288 | { | |
dbc7f069 | 4289 | return __sched_setscheduler(p, attr, true, true); |
d50dde5a DF |
4290 | } |
4291 | EXPORT_SYMBOL_GPL(sched_setattr); | |
4292 | ||
961ccddd RR |
4293 | /** |
4294 | * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. | |
4295 | * @p: the task in question. | |
4296 | * @policy: new policy. | |
4297 | * @param: structure containing the new RT priority. | |
4298 | * | |
4299 | * Just like sched_setscheduler, only don't bother checking if the | |
4300 | * current context has permission. For example, this is needed in | |
4301 | * stop_machine(): we create temporary high priority worker threads, | |
4302 | * but our caller might not have that capability. | |
e69f6186 YB |
4303 | * |
4304 | * Return: 0 on success. An error code otherwise. | |
961ccddd RR |
4305 | */ |
4306 | int sched_setscheduler_nocheck(struct task_struct *p, int policy, | |
fe7de49f | 4307 | const struct sched_param *param) |
961ccddd | 4308 | { |
7479f3c9 | 4309 | return _sched_setscheduler(p, policy, param, false); |
961ccddd | 4310 | } |
84778472 | 4311 | EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); |
961ccddd | 4312 | |
95cdf3b7 IM |
4313 | static int |
4314 | do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) | |
1da177e4 | 4315 | { |
1da177e4 LT |
4316 | struct sched_param lparam; |
4317 | struct task_struct *p; | |
36c8b586 | 4318 | int retval; |
1da177e4 LT |
4319 | |
4320 | if (!param || pid < 0) | |
4321 | return -EINVAL; | |
4322 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) | |
4323 | return -EFAULT; | |
5fe1d75f ON |
4324 | |
4325 | rcu_read_lock(); | |
4326 | retval = -ESRCH; | |
1da177e4 | 4327 | p = find_process_by_pid(pid); |
5fe1d75f ON |
4328 | if (p != NULL) |
4329 | retval = sched_setscheduler(p, policy, &lparam); | |
4330 | rcu_read_unlock(); | |
36c8b586 | 4331 | |
1da177e4 LT |
4332 | return retval; |
4333 | } | |
4334 | ||
d50dde5a DF |
4335 | /* |
4336 | * Mimics kernel/events/core.c perf_copy_attr(). | |
4337 | */ | |
d1ccc66d | 4338 | static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) |
d50dde5a DF |
4339 | { |
4340 | u32 size; | |
4341 | int ret; | |
4342 | ||
4343 | if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) | |
4344 | return -EFAULT; | |
4345 | ||
d1ccc66d | 4346 | /* Zero the full structure, so that a short copy will be nice: */ |
d50dde5a DF |
4347 | memset(attr, 0, sizeof(*attr)); |
4348 | ||
4349 | ret = get_user(size, &uattr->size); | |
4350 | if (ret) | |
4351 | return ret; | |
4352 | ||
d1ccc66d IM |
4353 | /* Bail out on silly large: */ |
4354 | if (size > PAGE_SIZE) | |
d50dde5a DF |
4355 | goto err_size; |
4356 | ||
d1ccc66d IM |
4357 | /* ABI compatibility quirk: */ |
4358 | if (!size) | |
d50dde5a DF |
4359 | size = SCHED_ATTR_SIZE_VER0; |
4360 | ||
4361 | if (size < SCHED_ATTR_SIZE_VER0) | |
4362 | goto err_size; | |
4363 | ||
4364 | /* | |
4365 | * If we're handed a bigger struct than we know of, | |
4366 | * ensure all the unknown bits are 0 - i.e. new | |
4367 | * user-space does not rely on any kernel feature | |
4368 | * extensions we dont know about yet. | |
4369 | */ | |
4370 | if (size > sizeof(*attr)) { | |
4371 | unsigned char __user *addr; | |
4372 | unsigned char __user *end; | |
4373 | unsigned char val; | |
4374 | ||
4375 | addr = (void __user *)uattr + sizeof(*attr); | |
4376 | end = (void __user *)uattr + size; | |
4377 | ||
4378 | for (; addr < end; addr++) { | |
4379 | ret = get_user(val, addr); | |
4380 | if (ret) | |
4381 | return ret; | |
4382 | if (val) | |
4383 | goto err_size; | |
4384 | } | |
4385 | size = sizeof(*attr); | |
4386 | } | |
4387 | ||
4388 | ret = copy_from_user(attr, uattr, size); | |
4389 | if (ret) | |
4390 | return -EFAULT; | |
4391 | ||
4392 | /* | |
d1ccc66d | 4393 | * XXX: Do we want to be lenient like existing syscalls; or do we want |
d50dde5a DF |
4394 | * to be strict and return an error on out-of-bounds values? |
4395 | */ | |
75e45d51 | 4396 | attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); |
d50dde5a | 4397 | |
e78c7bca | 4398 | return 0; |
d50dde5a DF |
4399 | |
4400 | err_size: | |
4401 | put_user(sizeof(*attr), &uattr->size); | |
e78c7bca | 4402 | return -E2BIG; |
d50dde5a DF |
4403 | } |
4404 | ||
1da177e4 LT |
4405 | /** |
4406 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority | |
4407 | * @pid: the pid in question. | |
4408 | * @policy: new policy. | |
4409 | * @param: structure containing the new RT priority. | |
e69f6186 YB |
4410 | * |
4411 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4412 | */ |
d1ccc66d | 4413 | SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param) |
1da177e4 | 4414 | { |
c21761f1 JB |
4415 | if (policy < 0) |
4416 | return -EINVAL; | |
4417 | ||
1da177e4 LT |
4418 | return do_sched_setscheduler(pid, policy, param); |
4419 | } | |
4420 | ||
4421 | /** | |
4422 | * sys_sched_setparam - set/change the RT priority of a thread | |
4423 | * @pid: the pid in question. | |
4424 | * @param: structure containing the new RT priority. | |
e69f6186 YB |
4425 | * |
4426 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4427 | */ |
5add95d4 | 4428 | SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) |
1da177e4 | 4429 | { |
c13db6b1 | 4430 | return do_sched_setscheduler(pid, SETPARAM_POLICY, param); |
1da177e4 LT |
4431 | } |
4432 | ||
d50dde5a DF |
4433 | /** |
4434 | * sys_sched_setattr - same as above, but with extended sched_attr | |
4435 | * @pid: the pid in question. | |
5778fccf | 4436 | * @uattr: structure containing the extended parameters. |
db66d756 | 4437 | * @flags: for future extension. |
d50dde5a | 4438 | */ |
6d35ab48 PZ |
4439 | SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, |
4440 | unsigned int, flags) | |
d50dde5a DF |
4441 | { |
4442 | struct sched_attr attr; | |
4443 | struct task_struct *p; | |
4444 | int retval; | |
4445 | ||
6d35ab48 | 4446 | if (!uattr || pid < 0 || flags) |
d50dde5a DF |
4447 | return -EINVAL; |
4448 | ||
143cf23d MK |
4449 | retval = sched_copy_attr(uattr, &attr); |
4450 | if (retval) | |
4451 | return retval; | |
d50dde5a | 4452 | |
b14ed2c2 | 4453 | if ((int)attr.sched_policy < 0) |
dbdb2275 | 4454 | return -EINVAL; |
d50dde5a DF |
4455 | |
4456 | rcu_read_lock(); | |
4457 | retval = -ESRCH; | |
4458 | p = find_process_by_pid(pid); | |
4459 | if (p != NULL) | |
4460 | retval = sched_setattr(p, &attr); | |
4461 | rcu_read_unlock(); | |
4462 | ||
4463 | return retval; | |
4464 | } | |
4465 | ||
1da177e4 LT |
4466 | /** |
4467 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread | |
4468 | * @pid: the pid in question. | |
e69f6186 YB |
4469 | * |
4470 | * Return: On success, the policy of the thread. Otherwise, a negative error | |
4471 | * code. | |
1da177e4 | 4472 | */ |
5add95d4 | 4473 | SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) |
1da177e4 | 4474 | { |
36c8b586 | 4475 | struct task_struct *p; |
3a5c359a | 4476 | int retval; |
1da177e4 LT |
4477 | |
4478 | if (pid < 0) | |
3a5c359a | 4479 | return -EINVAL; |
1da177e4 LT |
4480 | |
4481 | retval = -ESRCH; | |
5fe85be0 | 4482 | rcu_read_lock(); |
1da177e4 LT |
4483 | p = find_process_by_pid(pid); |
4484 | if (p) { | |
4485 | retval = security_task_getscheduler(p); | |
4486 | if (!retval) | |
ca94c442 LP |
4487 | retval = p->policy |
4488 | | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); | |
1da177e4 | 4489 | } |
5fe85be0 | 4490 | rcu_read_unlock(); |
1da177e4 LT |
4491 | return retval; |
4492 | } | |
4493 | ||
4494 | /** | |
ca94c442 | 4495 | * sys_sched_getparam - get the RT priority of a thread |
1da177e4 LT |
4496 | * @pid: the pid in question. |
4497 | * @param: structure containing the RT priority. | |
e69f6186 YB |
4498 | * |
4499 | * Return: On success, 0 and the RT priority is in @param. Otherwise, an error | |
4500 | * code. | |
1da177e4 | 4501 | */ |
5add95d4 | 4502 | SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) |
1da177e4 | 4503 | { |
ce5f7f82 | 4504 | struct sched_param lp = { .sched_priority = 0 }; |
36c8b586 | 4505 | struct task_struct *p; |
3a5c359a | 4506 | int retval; |
1da177e4 LT |
4507 | |
4508 | if (!param || pid < 0) | |
3a5c359a | 4509 | return -EINVAL; |
1da177e4 | 4510 | |
5fe85be0 | 4511 | rcu_read_lock(); |
1da177e4 LT |
4512 | p = find_process_by_pid(pid); |
4513 | retval = -ESRCH; | |
4514 | if (!p) | |
4515 | goto out_unlock; | |
4516 | ||
4517 | retval = security_task_getscheduler(p); | |
4518 | if (retval) | |
4519 | goto out_unlock; | |
4520 | ||
ce5f7f82 PZ |
4521 | if (task_has_rt_policy(p)) |
4522 | lp.sched_priority = p->rt_priority; | |
5fe85be0 | 4523 | rcu_read_unlock(); |
1da177e4 LT |
4524 | |
4525 | /* | |
4526 | * This one might sleep, we cannot do it with a spinlock held ... | |
4527 | */ | |
4528 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; | |
4529 | ||
1da177e4 LT |
4530 | return retval; |
4531 | ||
4532 | out_unlock: | |
5fe85be0 | 4533 | rcu_read_unlock(); |
1da177e4 LT |
4534 | return retval; |
4535 | } | |
4536 | ||
d50dde5a DF |
4537 | static int sched_read_attr(struct sched_attr __user *uattr, |
4538 | struct sched_attr *attr, | |
4539 | unsigned int usize) | |
4540 | { | |
4541 | int ret; | |
4542 | ||
4543 | if (!access_ok(VERIFY_WRITE, uattr, usize)) | |
4544 | return -EFAULT; | |
4545 | ||
4546 | /* | |
4547 | * If we're handed a smaller struct than we know of, | |
4548 | * ensure all the unknown bits are 0 - i.e. old | |
4549 | * user-space does not get uncomplete information. | |
4550 | */ | |
4551 | if (usize < sizeof(*attr)) { | |
4552 | unsigned char *addr; | |
4553 | unsigned char *end; | |
4554 | ||
4555 | addr = (void *)attr + usize; | |
4556 | end = (void *)attr + sizeof(*attr); | |
4557 | ||
4558 | for (; addr < end; addr++) { | |
4559 | if (*addr) | |
22400674 | 4560 | return -EFBIG; |
d50dde5a DF |
4561 | } |
4562 | ||
4563 | attr->size = usize; | |
4564 | } | |
4565 | ||
4efbc454 | 4566 | ret = copy_to_user(uattr, attr, attr->size); |
d50dde5a DF |
4567 | if (ret) |
4568 | return -EFAULT; | |
4569 | ||
22400674 | 4570 | return 0; |
d50dde5a DF |
4571 | } |
4572 | ||
4573 | /** | |
aab03e05 | 4574 | * sys_sched_getattr - similar to sched_getparam, but with sched_attr |
d50dde5a | 4575 | * @pid: the pid in question. |
5778fccf | 4576 | * @uattr: structure containing the extended parameters. |
d50dde5a | 4577 | * @size: sizeof(attr) for fwd/bwd comp. |
db66d756 | 4578 | * @flags: for future extension. |
d50dde5a | 4579 | */ |
6d35ab48 PZ |
4580 | SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, |
4581 | unsigned int, size, unsigned int, flags) | |
d50dde5a DF |
4582 | { |
4583 | struct sched_attr attr = { | |
4584 | .size = sizeof(struct sched_attr), | |
4585 | }; | |
4586 | struct task_struct *p; | |
4587 | int retval; | |
4588 | ||
4589 | if (!uattr || pid < 0 || size > PAGE_SIZE || | |
6d35ab48 | 4590 | size < SCHED_ATTR_SIZE_VER0 || flags) |
d50dde5a DF |
4591 | return -EINVAL; |
4592 | ||
4593 | rcu_read_lock(); | |
4594 | p = find_process_by_pid(pid); | |
4595 | retval = -ESRCH; | |
4596 | if (!p) | |
4597 | goto out_unlock; | |
4598 | ||
4599 | retval = security_task_getscheduler(p); | |
4600 | if (retval) | |
4601 | goto out_unlock; | |
4602 | ||
4603 | attr.sched_policy = p->policy; | |
7479f3c9 PZ |
4604 | if (p->sched_reset_on_fork) |
4605 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; | |
aab03e05 DF |
4606 | if (task_has_dl_policy(p)) |
4607 | __getparam_dl(p, &attr); | |
4608 | else if (task_has_rt_policy(p)) | |
d50dde5a DF |
4609 | attr.sched_priority = p->rt_priority; |
4610 | else | |
d0ea0268 | 4611 | attr.sched_nice = task_nice(p); |
d50dde5a DF |
4612 | |
4613 | rcu_read_unlock(); | |
4614 | ||
4615 | retval = sched_read_attr(uattr, &attr, size); | |
4616 | return retval; | |
4617 | ||
4618 | out_unlock: | |
4619 | rcu_read_unlock(); | |
4620 | return retval; | |
4621 | } | |
4622 | ||
96f874e2 | 4623 | long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) |
1da177e4 | 4624 | { |
5a16f3d3 | 4625 | cpumask_var_t cpus_allowed, new_mask; |
36c8b586 IM |
4626 | struct task_struct *p; |
4627 | int retval; | |
1da177e4 | 4628 | |
23f5d142 | 4629 | rcu_read_lock(); |
1da177e4 LT |
4630 | |
4631 | p = find_process_by_pid(pid); | |
4632 | if (!p) { | |
23f5d142 | 4633 | rcu_read_unlock(); |
1da177e4 LT |
4634 | return -ESRCH; |
4635 | } | |
4636 | ||
23f5d142 | 4637 | /* Prevent p going away */ |
1da177e4 | 4638 | get_task_struct(p); |
23f5d142 | 4639 | rcu_read_unlock(); |
1da177e4 | 4640 | |
14a40ffc TH |
4641 | if (p->flags & PF_NO_SETAFFINITY) { |
4642 | retval = -EINVAL; | |
4643 | goto out_put_task; | |
4644 | } | |
5a16f3d3 RR |
4645 | if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { |
4646 | retval = -ENOMEM; | |
4647 | goto out_put_task; | |
4648 | } | |
4649 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { | |
4650 | retval = -ENOMEM; | |
4651 | goto out_free_cpus_allowed; | |
4652 | } | |
1da177e4 | 4653 | retval = -EPERM; |
4c44aaaf EB |
4654 | if (!check_same_owner(p)) { |
4655 | rcu_read_lock(); | |
4656 | if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { | |
4657 | rcu_read_unlock(); | |
16303ab2 | 4658 | goto out_free_new_mask; |
4c44aaaf EB |
4659 | } |
4660 | rcu_read_unlock(); | |
4661 | } | |
1da177e4 | 4662 | |
b0ae1981 | 4663 | retval = security_task_setscheduler(p); |
e7834f8f | 4664 | if (retval) |
16303ab2 | 4665 | goto out_free_new_mask; |
e7834f8f | 4666 | |
e4099a5e PZ |
4667 | |
4668 | cpuset_cpus_allowed(p, cpus_allowed); | |
4669 | cpumask_and(new_mask, in_mask, cpus_allowed); | |
4670 | ||
332ac17e DF |
4671 | /* |
4672 | * Since bandwidth control happens on root_domain basis, | |
4673 | * if admission test is enabled, we only admit -deadline | |
4674 | * tasks allowed to run on all the CPUs in the task's | |
4675 | * root_domain. | |
4676 | */ | |
4677 | #ifdef CONFIG_SMP | |
f1e3a093 KT |
4678 | if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { |
4679 | rcu_read_lock(); | |
4680 | if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { | |
332ac17e | 4681 | retval = -EBUSY; |
f1e3a093 | 4682 | rcu_read_unlock(); |
16303ab2 | 4683 | goto out_free_new_mask; |
332ac17e | 4684 | } |
f1e3a093 | 4685 | rcu_read_unlock(); |
332ac17e DF |
4686 | } |
4687 | #endif | |
49246274 | 4688 | again: |
25834c73 | 4689 | retval = __set_cpus_allowed_ptr(p, new_mask, true); |
1da177e4 | 4690 | |
8707d8b8 | 4691 | if (!retval) { |
5a16f3d3 RR |
4692 | cpuset_cpus_allowed(p, cpus_allowed); |
4693 | if (!cpumask_subset(new_mask, cpus_allowed)) { | |
8707d8b8 PM |
4694 | /* |
4695 | * We must have raced with a concurrent cpuset | |
4696 | * update. Just reset the cpus_allowed to the | |
4697 | * cpuset's cpus_allowed | |
4698 | */ | |
5a16f3d3 | 4699 | cpumask_copy(new_mask, cpus_allowed); |
8707d8b8 PM |
4700 | goto again; |
4701 | } | |
4702 | } | |
16303ab2 | 4703 | out_free_new_mask: |
5a16f3d3 RR |
4704 | free_cpumask_var(new_mask); |
4705 | out_free_cpus_allowed: | |
4706 | free_cpumask_var(cpus_allowed); | |
4707 | out_put_task: | |
1da177e4 | 4708 | put_task_struct(p); |
1da177e4 LT |
4709 | return retval; |
4710 | } | |
4711 | ||
4712 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, | |
96f874e2 | 4713 | struct cpumask *new_mask) |
1da177e4 | 4714 | { |
96f874e2 RR |
4715 | if (len < cpumask_size()) |
4716 | cpumask_clear(new_mask); | |
4717 | else if (len > cpumask_size()) | |
4718 | len = cpumask_size(); | |
4719 | ||
1da177e4 LT |
4720 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; |
4721 | } | |
4722 | ||
4723 | /** | |
d1ccc66d | 4724 | * sys_sched_setaffinity - set the CPU affinity of a process |
1da177e4 LT |
4725 | * @pid: pid of the process |
4726 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
d1ccc66d | 4727 | * @user_mask_ptr: user-space pointer to the new CPU mask |
e69f6186 YB |
4728 | * |
4729 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4730 | */ |
5add95d4 HC |
4731 | SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, |
4732 | unsigned long __user *, user_mask_ptr) | |
1da177e4 | 4733 | { |
5a16f3d3 | 4734 | cpumask_var_t new_mask; |
1da177e4 LT |
4735 | int retval; |
4736 | ||
5a16f3d3 RR |
4737 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) |
4738 | return -ENOMEM; | |
1da177e4 | 4739 | |
5a16f3d3 RR |
4740 | retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); |
4741 | if (retval == 0) | |
4742 | retval = sched_setaffinity(pid, new_mask); | |
4743 | free_cpumask_var(new_mask); | |
4744 | return retval; | |
1da177e4 LT |
4745 | } |
4746 | ||
96f874e2 | 4747 | long sched_getaffinity(pid_t pid, struct cpumask *mask) |
1da177e4 | 4748 | { |
36c8b586 | 4749 | struct task_struct *p; |
31605683 | 4750 | unsigned long flags; |
1da177e4 | 4751 | int retval; |
1da177e4 | 4752 | |
23f5d142 | 4753 | rcu_read_lock(); |
1da177e4 LT |
4754 | |
4755 | retval = -ESRCH; | |
4756 | p = find_process_by_pid(pid); | |
4757 | if (!p) | |
4758 | goto out_unlock; | |
4759 | ||
e7834f8f DQ |
4760 | retval = security_task_getscheduler(p); |
4761 | if (retval) | |
4762 | goto out_unlock; | |
4763 | ||
013fdb80 | 4764 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
6acce3ef | 4765 | cpumask_and(mask, &p->cpus_allowed, cpu_active_mask); |
013fdb80 | 4766 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 LT |
4767 | |
4768 | out_unlock: | |
23f5d142 | 4769 | rcu_read_unlock(); |
1da177e4 | 4770 | |
9531b62f | 4771 | return retval; |
1da177e4 LT |
4772 | } |
4773 | ||
4774 | /** | |
d1ccc66d | 4775 | * sys_sched_getaffinity - get the CPU affinity of a process |
1da177e4 LT |
4776 | * @pid: pid of the process |
4777 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
d1ccc66d | 4778 | * @user_mask_ptr: user-space pointer to hold the current CPU mask |
e69f6186 | 4779 | * |
599b4840 ZW |
4780 | * Return: size of CPU mask copied to user_mask_ptr on success. An |
4781 | * error code otherwise. | |
1da177e4 | 4782 | */ |
5add95d4 HC |
4783 | SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, |
4784 | unsigned long __user *, user_mask_ptr) | |
1da177e4 LT |
4785 | { |
4786 | int ret; | |
f17c8607 | 4787 | cpumask_var_t mask; |
1da177e4 | 4788 | |
84fba5ec | 4789 | if ((len * BITS_PER_BYTE) < nr_cpu_ids) |
cd3d8031 KM |
4790 | return -EINVAL; |
4791 | if (len & (sizeof(unsigned long)-1)) | |
1da177e4 LT |
4792 | return -EINVAL; |
4793 | ||
f17c8607 RR |
4794 | if (!alloc_cpumask_var(&mask, GFP_KERNEL)) |
4795 | return -ENOMEM; | |
1da177e4 | 4796 | |
f17c8607 RR |
4797 | ret = sched_getaffinity(pid, mask); |
4798 | if (ret == 0) { | |
8bc037fb | 4799 | size_t retlen = min_t(size_t, len, cpumask_size()); |
cd3d8031 KM |
4800 | |
4801 | if (copy_to_user(user_mask_ptr, mask, retlen)) | |
f17c8607 RR |
4802 | ret = -EFAULT; |
4803 | else | |
cd3d8031 | 4804 | ret = retlen; |
f17c8607 RR |
4805 | } |
4806 | free_cpumask_var(mask); | |
1da177e4 | 4807 | |
f17c8607 | 4808 | return ret; |
1da177e4 LT |
4809 | } |
4810 | ||
4811 | /** | |
4812 | * sys_sched_yield - yield the current processor to other threads. | |
4813 | * | |
dd41f596 IM |
4814 | * This function yields the current CPU to other tasks. If there are no |
4815 | * other threads running on this CPU then this function will return. | |
e69f6186 YB |
4816 | * |
4817 | * Return: 0. | |
1da177e4 | 4818 | */ |
5add95d4 | 4819 | SYSCALL_DEFINE0(sched_yield) |
1da177e4 | 4820 | { |
8a8c69c3 PZ |
4821 | struct rq_flags rf; |
4822 | struct rq *rq; | |
4823 | ||
4824 | local_irq_disable(); | |
4825 | rq = this_rq(); | |
4826 | rq_lock(rq, &rf); | |
1da177e4 | 4827 | |
ae92882e | 4828 | schedstat_inc(rq->yld_count); |
4530d7ab | 4829 | current->sched_class->yield_task(rq); |
1da177e4 LT |
4830 | |
4831 | /* | |
4832 | * Since we are going to call schedule() anyway, there's | |
4833 | * no need to preempt or enable interrupts: | |
4834 | */ | |
8a8c69c3 PZ |
4835 | preempt_disable(); |
4836 | rq_unlock(rq, &rf); | |
ba74c144 | 4837 | sched_preempt_enable_no_resched(); |
1da177e4 LT |
4838 | |
4839 | schedule(); | |
4840 | ||
4841 | return 0; | |
4842 | } | |
4843 | ||
35a773a0 | 4844 | #ifndef CONFIG_PREEMPT |
02b67cc3 | 4845 | int __sched _cond_resched(void) |
1da177e4 | 4846 | { |
fe32d3cd | 4847 | if (should_resched(0)) { |
a18b5d01 | 4848 | preempt_schedule_common(); |
1da177e4 LT |
4849 | return 1; |
4850 | } | |
4851 | return 0; | |
4852 | } | |
02b67cc3 | 4853 | EXPORT_SYMBOL(_cond_resched); |
35a773a0 | 4854 | #endif |
1da177e4 LT |
4855 | |
4856 | /* | |
613afbf8 | 4857 | * __cond_resched_lock() - if a reschedule is pending, drop the given lock, |
1da177e4 LT |
4858 | * call schedule, and on return reacquire the lock. |
4859 | * | |
41a2d6cf | 4860 | * This works OK both with and without CONFIG_PREEMPT. We do strange low-level |
1da177e4 LT |
4861 | * operations here to prevent schedule() from being called twice (once via |
4862 | * spin_unlock(), once by hand). | |
4863 | */ | |
613afbf8 | 4864 | int __cond_resched_lock(spinlock_t *lock) |
1da177e4 | 4865 | { |
fe32d3cd | 4866 | int resched = should_resched(PREEMPT_LOCK_OFFSET); |
6df3cecb JK |
4867 | int ret = 0; |
4868 | ||
f607c668 PZ |
4869 | lockdep_assert_held(lock); |
4870 | ||
4a81e832 | 4871 | if (spin_needbreak(lock) || resched) { |
1da177e4 | 4872 | spin_unlock(lock); |
d86ee480 | 4873 | if (resched) |
a18b5d01 | 4874 | preempt_schedule_common(); |
95c354fe NP |
4875 | else |
4876 | cpu_relax(); | |
6df3cecb | 4877 | ret = 1; |
1da177e4 | 4878 | spin_lock(lock); |
1da177e4 | 4879 | } |
6df3cecb | 4880 | return ret; |
1da177e4 | 4881 | } |
613afbf8 | 4882 | EXPORT_SYMBOL(__cond_resched_lock); |
1da177e4 | 4883 | |
613afbf8 | 4884 | int __sched __cond_resched_softirq(void) |
1da177e4 LT |
4885 | { |
4886 | BUG_ON(!in_softirq()); | |
4887 | ||
fe32d3cd | 4888 | if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { |
98d82567 | 4889 | local_bh_enable(); |
a18b5d01 | 4890 | preempt_schedule_common(); |
1da177e4 LT |
4891 | local_bh_disable(); |
4892 | return 1; | |
4893 | } | |
4894 | return 0; | |
4895 | } | |
613afbf8 | 4896 | EXPORT_SYMBOL(__cond_resched_softirq); |
1da177e4 | 4897 | |
1da177e4 LT |
4898 | /** |
4899 | * yield - yield the current processor to other threads. | |
4900 | * | |
8e3fabfd PZ |
4901 | * Do not ever use this function, there's a 99% chance you're doing it wrong. |
4902 | * | |
4903 | * The scheduler is at all times free to pick the calling task as the most | |
4904 | * eligible task to run, if removing the yield() call from your code breaks | |
4905 | * it, its already broken. | |
4906 | * | |
4907 | * Typical broken usage is: | |
4908 | * | |
4909 | * while (!event) | |
d1ccc66d | 4910 | * yield(); |
8e3fabfd PZ |
4911 | * |
4912 | * where one assumes that yield() will let 'the other' process run that will | |
4913 | * make event true. If the current task is a SCHED_FIFO task that will never | |
4914 | * happen. Never use yield() as a progress guarantee!! | |
4915 | * | |
4916 | * If you want to use yield() to wait for something, use wait_event(). | |
4917 | * If you want to use yield() to be 'nice' for others, use cond_resched(). | |
4918 | * If you still want to use yield(), do not! | |
1da177e4 LT |
4919 | */ |
4920 | void __sched yield(void) | |
4921 | { | |
4922 | set_current_state(TASK_RUNNING); | |
4923 | sys_sched_yield(); | |
4924 | } | |
1da177e4 LT |
4925 | EXPORT_SYMBOL(yield); |
4926 | ||
d95f4122 MG |
4927 | /** |
4928 | * yield_to - yield the current processor to another thread in | |
4929 | * your thread group, or accelerate that thread toward the | |
4930 | * processor it's on. | |
16addf95 RD |
4931 | * @p: target task |
4932 | * @preempt: whether task preemption is allowed or not | |
d95f4122 MG |
4933 | * |
4934 | * It's the caller's job to ensure that the target task struct | |
4935 | * can't go away on us before we can do any checks. | |
4936 | * | |
e69f6186 | 4937 | * Return: |
7b270f60 PZ |
4938 | * true (>0) if we indeed boosted the target task. |
4939 | * false (0) if we failed to boost the target. | |
4940 | * -ESRCH if there's no task to yield to. | |
d95f4122 | 4941 | */ |
fa93384f | 4942 | int __sched yield_to(struct task_struct *p, bool preempt) |
d95f4122 MG |
4943 | { |
4944 | struct task_struct *curr = current; | |
4945 | struct rq *rq, *p_rq; | |
4946 | unsigned long flags; | |
c3c18640 | 4947 | int yielded = 0; |
d95f4122 MG |
4948 | |
4949 | local_irq_save(flags); | |
4950 | rq = this_rq(); | |
4951 | ||
4952 | again: | |
4953 | p_rq = task_rq(p); | |
7b270f60 PZ |
4954 | /* |
4955 | * If we're the only runnable task on the rq and target rq also | |
4956 | * has only one task, there's absolutely no point in yielding. | |
4957 | */ | |
4958 | if (rq->nr_running == 1 && p_rq->nr_running == 1) { | |
4959 | yielded = -ESRCH; | |
4960 | goto out_irq; | |
4961 | } | |
4962 | ||
d95f4122 | 4963 | double_rq_lock(rq, p_rq); |
39e24d8f | 4964 | if (task_rq(p) != p_rq) { |
d95f4122 MG |
4965 | double_rq_unlock(rq, p_rq); |
4966 | goto again; | |
4967 | } | |
4968 | ||
4969 | if (!curr->sched_class->yield_to_task) | |
7b270f60 | 4970 | goto out_unlock; |
d95f4122 MG |
4971 | |
4972 | if (curr->sched_class != p->sched_class) | |
7b270f60 | 4973 | goto out_unlock; |
d95f4122 MG |
4974 | |
4975 | if (task_running(p_rq, p) || p->state) | |
7b270f60 | 4976 | goto out_unlock; |
d95f4122 MG |
4977 | |
4978 | yielded = curr->sched_class->yield_to_task(rq, p, preempt); | |
6d1cafd8 | 4979 | if (yielded) { |
ae92882e | 4980 | schedstat_inc(rq->yld_count); |
6d1cafd8 VP |
4981 | /* |
4982 | * Make p's CPU reschedule; pick_next_entity takes care of | |
4983 | * fairness. | |
4984 | */ | |
4985 | if (preempt && rq != p_rq) | |
8875125e | 4986 | resched_curr(p_rq); |
6d1cafd8 | 4987 | } |
d95f4122 | 4988 | |
7b270f60 | 4989 | out_unlock: |
d95f4122 | 4990 | double_rq_unlock(rq, p_rq); |
7b270f60 | 4991 | out_irq: |
d95f4122 MG |
4992 | local_irq_restore(flags); |
4993 | ||
7b270f60 | 4994 | if (yielded > 0) |
d95f4122 MG |
4995 | schedule(); |
4996 | ||
4997 | return yielded; | |
4998 | } | |
4999 | EXPORT_SYMBOL_GPL(yield_to); | |
5000 | ||
10ab5643 TH |
5001 | int io_schedule_prepare(void) |
5002 | { | |
5003 | int old_iowait = current->in_iowait; | |
5004 | ||
5005 | current->in_iowait = 1; | |
5006 | blk_schedule_flush_plug(current); | |
5007 | ||
5008 | return old_iowait; | |
5009 | } | |
5010 | ||
5011 | void io_schedule_finish(int token) | |
5012 | { | |
5013 | current->in_iowait = token; | |
5014 | } | |
5015 | ||
1da177e4 | 5016 | /* |
41a2d6cf | 5017 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so |
1da177e4 | 5018 | * that process accounting knows that this is a task in IO wait state. |
1da177e4 | 5019 | */ |
1da177e4 LT |
5020 | long __sched io_schedule_timeout(long timeout) |
5021 | { | |
10ab5643 | 5022 | int token; |
1da177e4 LT |
5023 | long ret; |
5024 | ||
10ab5643 | 5025 | token = io_schedule_prepare(); |
1da177e4 | 5026 | ret = schedule_timeout(timeout); |
10ab5643 | 5027 | io_schedule_finish(token); |
9cff8ade | 5028 | |
1da177e4 LT |
5029 | return ret; |
5030 | } | |
9cff8ade | 5031 | EXPORT_SYMBOL(io_schedule_timeout); |
1da177e4 | 5032 | |
10ab5643 TH |
5033 | void io_schedule(void) |
5034 | { | |
5035 | int token; | |
5036 | ||
5037 | token = io_schedule_prepare(); | |
5038 | schedule(); | |
5039 | io_schedule_finish(token); | |
5040 | } | |
5041 | EXPORT_SYMBOL(io_schedule); | |
5042 | ||
1da177e4 LT |
5043 | /** |
5044 | * sys_sched_get_priority_max - return maximum RT priority. | |
5045 | * @policy: scheduling class. | |
5046 | * | |
e69f6186 YB |
5047 | * Return: On success, this syscall returns the maximum |
5048 | * rt_priority that can be used by a given scheduling class. | |
5049 | * On failure, a negative error code is returned. | |
1da177e4 | 5050 | */ |
5add95d4 | 5051 | SYSCALL_DEFINE1(sched_get_priority_max, int, policy) |
1da177e4 LT |
5052 | { |
5053 | int ret = -EINVAL; | |
5054 | ||
5055 | switch (policy) { | |
5056 | case SCHED_FIFO: | |
5057 | case SCHED_RR: | |
5058 | ret = MAX_USER_RT_PRIO-1; | |
5059 | break; | |
aab03e05 | 5060 | case SCHED_DEADLINE: |
1da177e4 | 5061 | case SCHED_NORMAL: |
b0a9499c | 5062 | case SCHED_BATCH: |
dd41f596 | 5063 | case SCHED_IDLE: |
1da177e4 LT |
5064 | ret = 0; |
5065 | break; | |
5066 | } | |
5067 | return ret; | |
5068 | } | |
5069 | ||
5070 | /** | |
5071 | * sys_sched_get_priority_min - return minimum RT priority. | |
5072 | * @policy: scheduling class. | |
5073 | * | |
e69f6186 YB |
5074 | * Return: On success, this syscall returns the minimum |
5075 | * rt_priority that can be used by a given scheduling class. | |
5076 | * On failure, a negative error code is returned. | |
1da177e4 | 5077 | */ |
5add95d4 | 5078 | SYSCALL_DEFINE1(sched_get_priority_min, int, policy) |
1da177e4 LT |
5079 | { |
5080 | int ret = -EINVAL; | |
5081 | ||
5082 | switch (policy) { | |
5083 | case SCHED_FIFO: | |
5084 | case SCHED_RR: | |
5085 | ret = 1; | |
5086 | break; | |
aab03e05 | 5087 | case SCHED_DEADLINE: |
1da177e4 | 5088 | case SCHED_NORMAL: |
b0a9499c | 5089 | case SCHED_BATCH: |
dd41f596 | 5090 | case SCHED_IDLE: |
1da177e4 LT |
5091 | ret = 0; |
5092 | } | |
5093 | return ret; | |
5094 | } | |
5095 | ||
5096 | /** | |
5097 | * sys_sched_rr_get_interval - return the default timeslice of a process. | |
5098 | * @pid: pid of the process. | |
5099 | * @interval: userspace pointer to the timeslice value. | |
5100 | * | |
5101 | * this syscall writes the default timeslice value of a given process | |
5102 | * into the user-space timespec buffer. A value of '0' means infinity. | |
e69f6186 YB |
5103 | * |
5104 | * Return: On success, 0 and the timeslice is in @interval. Otherwise, | |
5105 | * an error code. | |
1da177e4 | 5106 | */ |
17da2bd9 | 5107 | SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, |
754fe8d2 | 5108 | struct timespec __user *, interval) |
1da177e4 | 5109 | { |
36c8b586 | 5110 | struct task_struct *p; |
a4ec24b4 | 5111 | unsigned int time_slice; |
eb580751 PZ |
5112 | struct rq_flags rf; |
5113 | struct timespec t; | |
dba091b9 | 5114 | struct rq *rq; |
3a5c359a | 5115 | int retval; |
1da177e4 LT |
5116 | |
5117 | if (pid < 0) | |
3a5c359a | 5118 | return -EINVAL; |
1da177e4 LT |
5119 | |
5120 | retval = -ESRCH; | |
1a551ae7 | 5121 | rcu_read_lock(); |
1da177e4 LT |
5122 | p = find_process_by_pid(pid); |
5123 | if (!p) | |
5124 | goto out_unlock; | |
5125 | ||
5126 | retval = security_task_getscheduler(p); | |
5127 | if (retval) | |
5128 | goto out_unlock; | |
5129 | ||
eb580751 | 5130 | rq = task_rq_lock(p, &rf); |
a57beec5 PZ |
5131 | time_slice = 0; |
5132 | if (p->sched_class->get_rr_interval) | |
5133 | time_slice = p->sched_class->get_rr_interval(rq, p); | |
eb580751 | 5134 | task_rq_unlock(rq, p, &rf); |
a4ec24b4 | 5135 | |
1a551ae7 | 5136 | rcu_read_unlock(); |
a4ec24b4 | 5137 | jiffies_to_timespec(time_slice, &t); |
1da177e4 | 5138 | retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; |
1da177e4 | 5139 | return retval; |
3a5c359a | 5140 | |
1da177e4 | 5141 | out_unlock: |
1a551ae7 | 5142 | rcu_read_unlock(); |
1da177e4 LT |
5143 | return retval; |
5144 | } | |
5145 | ||
82a1fcb9 | 5146 | void sched_show_task(struct task_struct *p) |
1da177e4 | 5147 | { |
1da177e4 | 5148 | unsigned long free = 0; |
4e79752c | 5149 | int ppid; |
c930b2c0 | 5150 | |
38200502 TH |
5151 | if (!try_get_task_stack(p)) |
5152 | return; | |
20435d84 XX |
5153 | |
5154 | printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p)); | |
5155 | ||
5156 | if (p->state == TASK_RUNNING) | |
3df0fc5b | 5157 | printk(KERN_CONT " running task "); |
1da177e4 | 5158 | #ifdef CONFIG_DEBUG_STACK_USAGE |
7c9f8861 | 5159 | free = stack_not_used(p); |
1da177e4 | 5160 | #endif |
a90e984c | 5161 | ppid = 0; |
4e79752c | 5162 | rcu_read_lock(); |
a90e984c ON |
5163 | if (pid_alive(p)) |
5164 | ppid = task_pid_nr(rcu_dereference(p->real_parent)); | |
4e79752c | 5165 | rcu_read_unlock(); |
3df0fc5b | 5166 | printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, |
4e79752c | 5167 | task_pid_nr(p), ppid, |
aa47b7e0 | 5168 | (unsigned long)task_thread_info(p)->flags); |
1da177e4 | 5169 | |
3d1cb205 | 5170 | print_worker_info(KERN_INFO, p); |
5fb5e6de | 5171 | show_stack(p, NULL); |
38200502 | 5172 | put_task_stack(p); |
1da177e4 LT |
5173 | } |
5174 | ||
5d68cc95 PZ |
5175 | static inline bool |
5176 | state_filter_match(unsigned long state_filter, struct task_struct *p) | |
5177 | { | |
5178 | /* no filter, everything matches */ | |
5179 | if (!state_filter) | |
5180 | return true; | |
5181 | ||
5182 | /* filter, but doesn't match */ | |
5183 | if (!(p->state & state_filter)) | |
5184 | return false; | |
5185 | ||
5186 | /* | |
5187 | * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows | |
5188 | * TASK_KILLABLE). | |
5189 | */ | |
5190 | if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE) | |
5191 | return false; | |
5192 | ||
5193 | return true; | |
5194 | } | |
5195 | ||
5196 | ||
e59e2ae2 | 5197 | void show_state_filter(unsigned long state_filter) |
1da177e4 | 5198 | { |
36c8b586 | 5199 | struct task_struct *g, *p; |
1da177e4 | 5200 | |
4bd77321 | 5201 | #if BITS_PER_LONG == 32 |
3df0fc5b PZ |
5202 | printk(KERN_INFO |
5203 | " task PC stack pid father\n"); | |
1da177e4 | 5204 | #else |
3df0fc5b PZ |
5205 | printk(KERN_INFO |
5206 | " task PC stack pid father\n"); | |
1da177e4 | 5207 | #endif |
510f5acc | 5208 | rcu_read_lock(); |
5d07f420 | 5209 | for_each_process_thread(g, p) { |
1da177e4 LT |
5210 | /* |
5211 | * reset the NMI-timeout, listing all files on a slow | |
25985edc | 5212 | * console might take a lot of time: |
57675cb9 AR |
5213 | * Also, reset softlockup watchdogs on all CPUs, because |
5214 | * another CPU might be blocked waiting for us to process | |
5215 | * an IPI. | |
1da177e4 LT |
5216 | */ |
5217 | touch_nmi_watchdog(); | |
57675cb9 | 5218 | touch_all_softlockup_watchdogs(); |
5d68cc95 | 5219 | if (state_filter_match(state_filter, p)) |
82a1fcb9 | 5220 | sched_show_task(p); |
5d07f420 | 5221 | } |
1da177e4 | 5222 | |
dd41f596 | 5223 | #ifdef CONFIG_SCHED_DEBUG |
fb90a6e9 RV |
5224 | if (!state_filter) |
5225 | sysrq_sched_debug_show(); | |
dd41f596 | 5226 | #endif |
510f5acc | 5227 | rcu_read_unlock(); |
e59e2ae2 IM |
5228 | /* |
5229 | * Only show locks if all tasks are dumped: | |
5230 | */ | |
93335a21 | 5231 | if (!state_filter) |
e59e2ae2 | 5232 | debug_show_all_locks(); |
1da177e4 LT |
5233 | } |
5234 | ||
f340c0d1 IM |
5235 | /** |
5236 | * init_idle - set up an idle thread for a given CPU | |
5237 | * @idle: task in question | |
d1ccc66d | 5238 | * @cpu: CPU the idle task belongs to |
f340c0d1 IM |
5239 | * |
5240 | * NOTE: this function does not set the idle thread's NEED_RESCHED | |
5241 | * flag, to make booting more robust. | |
5242 | */ | |
0db0628d | 5243 | void init_idle(struct task_struct *idle, int cpu) |
1da177e4 | 5244 | { |
70b97a7f | 5245 | struct rq *rq = cpu_rq(cpu); |
1da177e4 LT |
5246 | unsigned long flags; |
5247 | ||
25834c73 PZ |
5248 | raw_spin_lock_irqsave(&idle->pi_lock, flags); |
5249 | raw_spin_lock(&rq->lock); | |
5cbd54ef | 5250 | |
5e1576ed | 5251 | __sched_fork(0, idle); |
06b83b5f | 5252 | idle->state = TASK_RUNNING; |
dd41f596 | 5253 | idle->se.exec_start = sched_clock(); |
c1de45ca | 5254 | idle->flags |= PF_IDLE; |
dd41f596 | 5255 | |
e1b77c92 MR |
5256 | kasan_unpoison_task_stack(idle); |
5257 | ||
de9b8f5d PZ |
5258 | #ifdef CONFIG_SMP |
5259 | /* | |
5260 | * Its possible that init_idle() gets called multiple times on a task, | |
5261 | * in that case do_set_cpus_allowed() will not do the right thing. | |
5262 | * | |
5263 | * And since this is boot we can forgo the serialization. | |
5264 | */ | |
5265 | set_cpus_allowed_common(idle, cpumask_of(cpu)); | |
5266 | #endif | |
6506cf6c PZ |
5267 | /* |
5268 | * We're having a chicken and egg problem, even though we are | |
d1ccc66d | 5269 | * holding rq->lock, the CPU isn't yet set to this CPU so the |
6506cf6c PZ |
5270 | * lockdep check in task_group() will fail. |
5271 | * | |
5272 | * Similar case to sched_fork(). / Alternatively we could | |
5273 | * use task_rq_lock() here and obtain the other rq->lock. | |
5274 | * | |
5275 | * Silence PROVE_RCU | |
5276 | */ | |
5277 | rcu_read_lock(); | |
dd41f596 | 5278 | __set_task_cpu(idle, cpu); |
6506cf6c | 5279 | rcu_read_unlock(); |
1da177e4 | 5280 | |
1da177e4 | 5281 | rq->curr = rq->idle = idle; |
da0c1e65 | 5282 | idle->on_rq = TASK_ON_RQ_QUEUED; |
de9b8f5d | 5283 | #ifdef CONFIG_SMP |
3ca7a440 | 5284 | idle->on_cpu = 1; |
4866cde0 | 5285 | #endif |
25834c73 PZ |
5286 | raw_spin_unlock(&rq->lock); |
5287 | raw_spin_unlock_irqrestore(&idle->pi_lock, flags); | |
1da177e4 LT |
5288 | |
5289 | /* Set the preempt count _outside_ the spinlocks! */ | |
01028747 | 5290 | init_idle_preempt_count(idle, cpu); |
55cd5340 | 5291 | |
dd41f596 IM |
5292 | /* |
5293 | * The idle tasks have their own, simple scheduling class: | |
5294 | */ | |
5295 | idle->sched_class = &idle_sched_class; | |
868baf07 | 5296 | ftrace_graph_init_idle_task(idle, cpu); |
45eacc69 | 5297 | vtime_init_idle(idle, cpu); |
de9b8f5d | 5298 | #ifdef CONFIG_SMP |
f1c6f1a7 CE |
5299 | sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); |
5300 | #endif | |
19978ca6 IM |
5301 | } |
5302 | ||
e1d4eeec NP |
5303 | #ifdef CONFIG_SMP |
5304 | ||
f82f8042 JL |
5305 | int cpuset_cpumask_can_shrink(const struct cpumask *cur, |
5306 | const struct cpumask *trial) | |
5307 | { | |
06a76fe0 | 5308 | int ret = 1; |
f82f8042 | 5309 | |
bb2bc55a MG |
5310 | if (!cpumask_weight(cur)) |
5311 | return ret; | |
5312 | ||
06a76fe0 | 5313 | ret = dl_cpuset_cpumask_can_shrink(cur, trial); |
f82f8042 JL |
5314 | |
5315 | return ret; | |
5316 | } | |
5317 | ||
7f51412a JL |
5318 | int task_can_attach(struct task_struct *p, |
5319 | const struct cpumask *cs_cpus_allowed) | |
5320 | { | |
5321 | int ret = 0; | |
5322 | ||
5323 | /* | |
5324 | * Kthreads which disallow setaffinity shouldn't be moved | |
d1ccc66d | 5325 | * to a new cpuset; we don't want to change their CPU |
7f51412a JL |
5326 | * affinity and isolating such threads by their set of |
5327 | * allowed nodes is unnecessary. Thus, cpusets are not | |
5328 | * applicable for such threads. This prevents checking for | |
5329 | * success of set_cpus_allowed_ptr() on all attached tasks | |
5330 | * before cpus_allowed may be changed. | |
5331 | */ | |
5332 | if (p->flags & PF_NO_SETAFFINITY) { | |
5333 | ret = -EINVAL; | |
5334 | goto out; | |
5335 | } | |
5336 | ||
7f51412a | 5337 | if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, |
06a76fe0 NP |
5338 | cs_cpus_allowed)) |
5339 | ret = dl_task_can_attach(p, cs_cpus_allowed); | |
7f51412a | 5340 | |
7f51412a JL |
5341 | out: |
5342 | return ret; | |
5343 | } | |
5344 | ||
f2cb1360 | 5345 | bool sched_smp_initialized __read_mostly; |
e26fbffd | 5346 | |
e6628d5b MG |
5347 | #ifdef CONFIG_NUMA_BALANCING |
5348 | /* Migrate current task p to target_cpu */ | |
5349 | int migrate_task_to(struct task_struct *p, int target_cpu) | |
5350 | { | |
5351 | struct migration_arg arg = { p, target_cpu }; | |
5352 | int curr_cpu = task_cpu(p); | |
5353 | ||
5354 | if (curr_cpu == target_cpu) | |
5355 | return 0; | |
5356 | ||
0c98d344 | 5357 | if (!cpumask_test_cpu(target_cpu, &p->cpus_allowed)) |
e6628d5b MG |
5358 | return -EINVAL; |
5359 | ||
5360 | /* TODO: This is not properly updating schedstats */ | |
5361 | ||
286549dc | 5362 | trace_sched_move_numa(p, curr_cpu, target_cpu); |
e6628d5b MG |
5363 | return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); |
5364 | } | |
0ec8aa00 PZ |
5365 | |
5366 | /* | |
5367 | * Requeue a task on a given node and accurately track the number of NUMA | |
5368 | * tasks on the runqueues | |
5369 | */ | |
5370 | void sched_setnuma(struct task_struct *p, int nid) | |
5371 | { | |
da0c1e65 | 5372 | bool queued, running; |
eb580751 PZ |
5373 | struct rq_flags rf; |
5374 | struct rq *rq; | |
0ec8aa00 | 5375 | |
eb580751 | 5376 | rq = task_rq_lock(p, &rf); |
da0c1e65 | 5377 | queued = task_on_rq_queued(p); |
0ec8aa00 PZ |
5378 | running = task_current(rq, p); |
5379 | ||
da0c1e65 | 5380 | if (queued) |
1de64443 | 5381 | dequeue_task(rq, p, DEQUEUE_SAVE); |
0ec8aa00 | 5382 | if (running) |
f3cd1c4e | 5383 | put_prev_task(rq, p); |
0ec8aa00 PZ |
5384 | |
5385 | p->numa_preferred_nid = nid; | |
0ec8aa00 | 5386 | |
da0c1e65 | 5387 | if (queued) |
7134b3e9 | 5388 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
a399d233 | 5389 | if (running) |
b2bf6c31 | 5390 | set_curr_task(rq, p); |
eb580751 | 5391 | task_rq_unlock(rq, p, &rf); |
0ec8aa00 | 5392 | } |
5cc389bc | 5393 | #endif /* CONFIG_NUMA_BALANCING */ |
f7b4cddc | 5394 | |
1da177e4 | 5395 | #ifdef CONFIG_HOTPLUG_CPU |
054b9108 | 5396 | /* |
d1ccc66d | 5397 | * Ensure that the idle task is using init_mm right before its CPU goes |
48c5ccae | 5398 | * offline. |
054b9108 | 5399 | */ |
48c5ccae | 5400 | void idle_task_exit(void) |
1da177e4 | 5401 | { |
48c5ccae | 5402 | struct mm_struct *mm = current->active_mm; |
e76bd8d9 | 5403 | |
48c5ccae | 5404 | BUG_ON(cpu_online(smp_processor_id())); |
e76bd8d9 | 5405 | |
a53efe5f | 5406 | if (mm != &init_mm) { |
252d2a41 | 5407 | switch_mm(mm, &init_mm, current); |
a53efe5f MS |
5408 | finish_arch_post_lock_switch(); |
5409 | } | |
48c5ccae | 5410 | mmdrop(mm); |
1da177e4 LT |
5411 | } |
5412 | ||
5413 | /* | |
5d180232 PZ |
5414 | * Since this CPU is going 'away' for a while, fold any nr_active delta |
5415 | * we might have. Assumes we're called after migrate_tasks() so that the | |
d60585c5 TG |
5416 | * nr_active count is stable. We need to take the teardown thread which |
5417 | * is calling this into account, so we hand in adjust = 1 to the load | |
5418 | * calculation. | |
5d180232 PZ |
5419 | * |
5420 | * Also see the comment "Global load-average calculations". | |
1da177e4 | 5421 | */ |
5d180232 | 5422 | static void calc_load_migrate(struct rq *rq) |
1da177e4 | 5423 | { |
d60585c5 | 5424 | long delta = calc_load_fold_active(rq, 1); |
5d180232 PZ |
5425 | if (delta) |
5426 | atomic_long_add(delta, &calc_load_tasks); | |
1da177e4 LT |
5427 | } |
5428 | ||
3f1d2a31 PZ |
5429 | static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) |
5430 | { | |
5431 | } | |
5432 | ||
5433 | static const struct sched_class fake_sched_class = { | |
5434 | .put_prev_task = put_prev_task_fake, | |
5435 | }; | |
5436 | ||
5437 | static struct task_struct fake_task = { | |
5438 | /* | |
5439 | * Avoid pull_{rt,dl}_task() | |
5440 | */ | |
5441 | .prio = MAX_PRIO + 1, | |
5442 | .sched_class = &fake_sched_class, | |
5443 | }; | |
5444 | ||
48f24c4d | 5445 | /* |
48c5ccae PZ |
5446 | * Migrate all tasks from the rq, sleeping tasks will be migrated by |
5447 | * try_to_wake_up()->select_task_rq(). | |
5448 | * | |
5449 | * Called with rq->lock held even though we'er in stop_machine() and | |
5450 | * there's no concurrency possible, we hold the required locks anyway | |
5451 | * because of lock validation efforts. | |
1da177e4 | 5452 | */ |
8a8c69c3 | 5453 | static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf) |
1da177e4 | 5454 | { |
5e16bbc2 | 5455 | struct rq *rq = dead_rq; |
48c5ccae | 5456 | struct task_struct *next, *stop = rq->stop; |
8a8c69c3 | 5457 | struct rq_flags orf = *rf; |
48c5ccae | 5458 | int dest_cpu; |
1da177e4 LT |
5459 | |
5460 | /* | |
48c5ccae PZ |
5461 | * Fudge the rq selection such that the below task selection loop |
5462 | * doesn't get stuck on the currently eligible stop task. | |
5463 | * | |
5464 | * We're currently inside stop_machine() and the rq is either stuck | |
5465 | * in the stop_machine_cpu_stop() loop, or we're executing this code, | |
5466 | * either way we should never end up calling schedule() until we're | |
5467 | * done here. | |
1da177e4 | 5468 | */ |
48c5ccae | 5469 | rq->stop = NULL; |
48f24c4d | 5470 | |
77bd3970 FW |
5471 | /* |
5472 | * put_prev_task() and pick_next_task() sched | |
5473 | * class method both need to have an up-to-date | |
5474 | * value of rq->clock[_task] | |
5475 | */ | |
5476 | update_rq_clock(rq); | |
5477 | ||
5e16bbc2 | 5478 | for (;;) { |
48c5ccae PZ |
5479 | /* |
5480 | * There's this thread running, bail when that's the only | |
d1ccc66d | 5481 | * remaining thread: |
48c5ccae PZ |
5482 | */ |
5483 | if (rq->nr_running == 1) | |
dd41f596 | 5484 | break; |
48c5ccae | 5485 | |
cbce1a68 | 5486 | /* |
d1ccc66d | 5487 | * pick_next_task() assumes pinned rq->lock: |
cbce1a68 | 5488 | */ |
8a8c69c3 | 5489 | next = pick_next_task(rq, &fake_task, rf); |
48c5ccae | 5490 | BUG_ON(!next); |
5b713a3d | 5491 | put_prev_task(rq, next); |
e692ab53 | 5492 | |
5473e0cc WL |
5493 | /* |
5494 | * Rules for changing task_struct::cpus_allowed are holding | |
5495 | * both pi_lock and rq->lock, such that holding either | |
5496 | * stabilizes the mask. | |
5497 | * | |
5498 | * Drop rq->lock is not quite as disastrous as it usually is | |
5499 | * because !cpu_active at this point, which means load-balance | |
5500 | * will not interfere. Also, stop-machine. | |
5501 | */ | |
8a8c69c3 | 5502 | rq_unlock(rq, rf); |
5473e0cc | 5503 | raw_spin_lock(&next->pi_lock); |
8a8c69c3 | 5504 | rq_relock(rq, rf); |
5473e0cc WL |
5505 | |
5506 | /* | |
5507 | * Since we're inside stop-machine, _nothing_ should have | |
5508 | * changed the task, WARN if weird stuff happened, because in | |
5509 | * that case the above rq->lock drop is a fail too. | |
5510 | */ | |
5511 | if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { | |
5512 | raw_spin_unlock(&next->pi_lock); | |
5513 | continue; | |
5514 | } | |
5515 | ||
48c5ccae | 5516 | /* Find suitable destination for @next, with force if needed. */ |
5e16bbc2 | 5517 | dest_cpu = select_fallback_rq(dead_rq->cpu, next); |
8a8c69c3 | 5518 | rq = __migrate_task(rq, rf, next, dest_cpu); |
5e16bbc2 | 5519 | if (rq != dead_rq) { |
8a8c69c3 | 5520 | rq_unlock(rq, rf); |
5e16bbc2 | 5521 | rq = dead_rq; |
8a8c69c3 PZ |
5522 | *rf = orf; |
5523 | rq_relock(rq, rf); | |
5e16bbc2 | 5524 | } |
5473e0cc | 5525 | raw_spin_unlock(&next->pi_lock); |
1da177e4 | 5526 | } |
dce48a84 | 5527 | |
48c5ccae | 5528 | rq->stop = stop; |
dce48a84 | 5529 | } |
1da177e4 LT |
5530 | #endif /* CONFIG_HOTPLUG_CPU */ |
5531 | ||
f2cb1360 | 5532 | void set_rq_online(struct rq *rq) |
1f11eb6a GH |
5533 | { |
5534 | if (!rq->online) { | |
5535 | const struct sched_class *class; | |
5536 | ||
c6c4927b | 5537 | cpumask_set_cpu(rq->cpu, rq->rd->online); |
1f11eb6a GH |
5538 | rq->online = 1; |
5539 | ||
5540 | for_each_class(class) { | |
5541 | if (class->rq_online) | |
5542 | class->rq_online(rq); | |
5543 | } | |
5544 | } | |
5545 | } | |
5546 | ||
f2cb1360 | 5547 | void set_rq_offline(struct rq *rq) |
1f11eb6a GH |
5548 | { |
5549 | if (rq->online) { | |
5550 | const struct sched_class *class; | |
5551 | ||
5552 | for_each_class(class) { | |
5553 | if (class->rq_offline) | |
5554 | class->rq_offline(rq); | |
5555 | } | |
5556 | ||
c6c4927b | 5557 | cpumask_clear_cpu(rq->cpu, rq->rd->online); |
1f11eb6a GH |
5558 | rq->online = 0; |
5559 | } | |
5560 | } | |
5561 | ||
9cf7243d | 5562 | static void set_cpu_rq_start_time(unsigned int cpu) |
1da177e4 | 5563 | { |
969c7921 | 5564 | struct rq *rq = cpu_rq(cpu); |
1da177e4 | 5565 | |
a803f026 CM |
5566 | rq->age_stamp = sched_clock_cpu(cpu); |
5567 | } | |
5568 | ||
d1ccc66d IM |
5569 | /* |
5570 | * used to mark begin/end of suspend/resume: | |
5571 | */ | |
5572 | static int num_cpus_frozen; | |
d35be8ba | 5573 | |
1da177e4 | 5574 | /* |
3a101d05 TH |
5575 | * Update cpusets according to cpu_active mask. If cpusets are |
5576 | * disabled, cpuset_update_active_cpus() becomes a simple wrapper | |
5577 | * around partition_sched_domains(). | |
d35be8ba SB |
5578 | * |
5579 | * If we come here as part of a suspend/resume, don't touch cpusets because we | |
5580 | * want to restore it back to its original state upon resume anyway. | |
1da177e4 | 5581 | */ |
40190a78 | 5582 | static void cpuset_cpu_active(void) |
e761b772 | 5583 | { |
40190a78 | 5584 | if (cpuhp_tasks_frozen) { |
d35be8ba SB |
5585 | /* |
5586 | * num_cpus_frozen tracks how many CPUs are involved in suspend | |
5587 | * resume sequence. As long as this is not the last online | |
5588 | * operation in the resume sequence, just build a single sched | |
5589 | * domain, ignoring cpusets. | |
5590 | */ | |
50e76632 PZ |
5591 | partition_sched_domains(1, NULL, NULL); |
5592 | if (--num_cpus_frozen) | |
135fb3e1 | 5593 | return; |
d35be8ba SB |
5594 | /* |
5595 | * This is the last CPU online operation. So fall through and | |
5596 | * restore the original sched domains by considering the | |
5597 | * cpuset configurations. | |
5598 | */ | |
50e76632 | 5599 | cpuset_force_rebuild(); |
3a101d05 | 5600 | } |
30e03acd | 5601 | cpuset_update_active_cpus(); |
3a101d05 | 5602 | } |
e761b772 | 5603 | |
40190a78 | 5604 | static int cpuset_cpu_inactive(unsigned int cpu) |
3a101d05 | 5605 | { |
40190a78 | 5606 | if (!cpuhp_tasks_frozen) { |
06a76fe0 | 5607 | if (dl_cpu_busy(cpu)) |
135fb3e1 | 5608 | return -EBUSY; |
30e03acd | 5609 | cpuset_update_active_cpus(); |
135fb3e1 | 5610 | } else { |
d35be8ba SB |
5611 | num_cpus_frozen++; |
5612 | partition_sched_domains(1, NULL, NULL); | |
e761b772 | 5613 | } |
135fb3e1 | 5614 | return 0; |
e761b772 | 5615 | } |
e761b772 | 5616 | |
40190a78 | 5617 | int sched_cpu_activate(unsigned int cpu) |
135fb3e1 | 5618 | { |
7d976699 | 5619 | struct rq *rq = cpu_rq(cpu); |
8a8c69c3 | 5620 | struct rq_flags rf; |
7d976699 | 5621 | |
40190a78 | 5622 | set_cpu_active(cpu, true); |
135fb3e1 | 5623 | |
40190a78 | 5624 | if (sched_smp_initialized) { |
135fb3e1 | 5625 | sched_domains_numa_masks_set(cpu); |
40190a78 | 5626 | cpuset_cpu_active(); |
e761b772 | 5627 | } |
7d976699 TG |
5628 | |
5629 | /* | |
5630 | * Put the rq online, if not already. This happens: | |
5631 | * | |
5632 | * 1) In the early boot process, because we build the real domains | |
d1ccc66d | 5633 | * after all CPUs have been brought up. |
7d976699 TG |
5634 | * |
5635 | * 2) At runtime, if cpuset_cpu_active() fails to rebuild the | |
5636 | * domains. | |
5637 | */ | |
8a8c69c3 | 5638 | rq_lock_irqsave(rq, &rf); |
7d976699 TG |
5639 | if (rq->rd) { |
5640 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5641 | set_rq_online(rq); | |
5642 | } | |
8a8c69c3 | 5643 | rq_unlock_irqrestore(rq, &rf); |
7d976699 TG |
5644 | |
5645 | update_max_interval(); | |
5646 | ||
40190a78 | 5647 | return 0; |
135fb3e1 TG |
5648 | } |
5649 | ||
40190a78 | 5650 | int sched_cpu_deactivate(unsigned int cpu) |
135fb3e1 | 5651 | { |
135fb3e1 TG |
5652 | int ret; |
5653 | ||
40190a78 | 5654 | set_cpu_active(cpu, false); |
b2454caa PZ |
5655 | /* |
5656 | * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU | |
5657 | * users of this state to go away such that all new such users will | |
5658 | * observe it. | |
5659 | * | |
b2454caa PZ |
5660 | * Do sync before park smpboot threads to take care the rcu boost case. |
5661 | */ | |
d7d34d5e | 5662 | synchronize_rcu_mult(call_rcu, call_rcu_sched); |
40190a78 TG |
5663 | |
5664 | if (!sched_smp_initialized) | |
5665 | return 0; | |
5666 | ||
5667 | ret = cpuset_cpu_inactive(cpu); | |
5668 | if (ret) { | |
5669 | set_cpu_active(cpu, true); | |
5670 | return ret; | |
135fb3e1 | 5671 | } |
40190a78 TG |
5672 | sched_domains_numa_masks_clear(cpu); |
5673 | return 0; | |
135fb3e1 TG |
5674 | } |
5675 | ||
94baf7a5 TG |
5676 | static void sched_rq_cpu_starting(unsigned int cpu) |
5677 | { | |
5678 | struct rq *rq = cpu_rq(cpu); | |
5679 | ||
5680 | rq->calc_load_update = calc_load_update; | |
94baf7a5 TG |
5681 | update_max_interval(); |
5682 | } | |
5683 | ||
135fb3e1 TG |
5684 | int sched_cpu_starting(unsigned int cpu) |
5685 | { | |
5686 | set_cpu_rq_start_time(cpu); | |
94baf7a5 | 5687 | sched_rq_cpu_starting(cpu); |
135fb3e1 | 5688 | return 0; |
e761b772 | 5689 | } |
e761b772 | 5690 | |
f2785ddb TG |
5691 | #ifdef CONFIG_HOTPLUG_CPU |
5692 | int sched_cpu_dying(unsigned int cpu) | |
5693 | { | |
5694 | struct rq *rq = cpu_rq(cpu); | |
8a8c69c3 | 5695 | struct rq_flags rf; |
f2785ddb TG |
5696 | |
5697 | /* Handle pending wakeups and then migrate everything off */ | |
5698 | sched_ttwu_pending(); | |
8a8c69c3 PZ |
5699 | |
5700 | rq_lock_irqsave(rq, &rf); | |
f2785ddb TG |
5701 | if (rq->rd) { |
5702 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5703 | set_rq_offline(rq); | |
5704 | } | |
8a8c69c3 | 5705 | migrate_tasks(rq, &rf); |
f2785ddb | 5706 | BUG_ON(rq->nr_running != 1); |
8a8c69c3 PZ |
5707 | rq_unlock_irqrestore(rq, &rf); |
5708 | ||
f2785ddb TG |
5709 | calc_load_migrate(rq); |
5710 | update_max_interval(); | |
20a5c8cc | 5711 | nohz_balance_exit_idle(cpu); |
e5ef27d0 | 5712 | hrtick_clear(rq); |
f2785ddb TG |
5713 | return 0; |
5714 | } | |
5715 | #endif | |
5716 | ||
1b568f0a PZ |
5717 | #ifdef CONFIG_SCHED_SMT |
5718 | DEFINE_STATIC_KEY_FALSE(sched_smt_present); | |
5719 | ||
5720 | static void sched_init_smt(void) | |
5721 | { | |
5722 | /* | |
5723 | * We've enumerated all CPUs and will assume that if any CPU | |
5724 | * has SMT siblings, CPU0 will too. | |
5725 | */ | |
5726 | if (cpumask_weight(cpu_smt_mask(0)) > 1) | |
5727 | static_branch_enable(&sched_smt_present); | |
5728 | } | |
5729 | #else | |
5730 | static inline void sched_init_smt(void) { } | |
5731 | #endif | |
5732 | ||
1da177e4 LT |
5733 | void __init sched_init_smp(void) |
5734 | { | |
cb83b629 PZ |
5735 | sched_init_numa(); |
5736 | ||
6acce3ef PZ |
5737 | /* |
5738 | * There's no userspace yet to cause hotplug operations; hence all the | |
d1ccc66d | 5739 | * CPU masks are stable and all blatant races in the below code cannot |
6acce3ef PZ |
5740 | * happen. |
5741 | */ | |
712555ee | 5742 | mutex_lock(&sched_domains_mutex); |
8d5dc512 | 5743 | sched_init_domains(cpu_active_mask); |
712555ee | 5744 | mutex_unlock(&sched_domains_mutex); |
e761b772 | 5745 | |
5c1e1767 | 5746 | /* Move init over to a non-isolated CPU */ |
edb93821 | 5747 | if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0) |
5c1e1767 | 5748 | BUG(); |
19978ca6 | 5749 | sched_init_granularity(); |
4212823f | 5750 | |
0e3900e6 | 5751 | init_sched_rt_class(); |
1baca4ce | 5752 | init_sched_dl_class(); |
1b568f0a PZ |
5753 | |
5754 | sched_init_smt(); | |
5755 | ||
e26fbffd | 5756 | sched_smp_initialized = true; |
1da177e4 | 5757 | } |
e26fbffd TG |
5758 | |
5759 | static int __init migration_init(void) | |
5760 | { | |
94baf7a5 | 5761 | sched_rq_cpu_starting(smp_processor_id()); |
e26fbffd | 5762 | return 0; |
1da177e4 | 5763 | } |
e26fbffd TG |
5764 | early_initcall(migration_init); |
5765 | ||
1da177e4 LT |
5766 | #else |
5767 | void __init sched_init_smp(void) | |
5768 | { | |
19978ca6 | 5769 | sched_init_granularity(); |
1da177e4 LT |
5770 | } |
5771 | #endif /* CONFIG_SMP */ | |
5772 | ||
5773 | int in_sched_functions(unsigned long addr) | |
5774 | { | |
1da177e4 LT |
5775 | return in_lock_functions(addr) || |
5776 | (addr >= (unsigned long)__sched_text_start | |
5777 | && addr < (unsigned long)__sched_text_end); | |
5778 | } | |
5779 | ||
029632fb | 5780 | #ifdef CONFIG_CGROUP_SCHED |
27b4b931 LZ |
5781 | /* |
5782 | * Default task group. | |
5783 | * Every task in system belongs to this group at bootup. | |
5784 | */ | |
029632fb | 5785 | struct task_group root_task_group; |
35cf4e50 | 5786 | LIST_HEAD(task_groups); |
b0367629 WL |
5787 | |
5788 | /* Cacheline aligned slab cache for task_group */ | |
5789 | static struct kmem_cache *task_group_cache __read_mostly; | |
052f1dc7 | 5790 | #endif |
6f505b16 | 5791 | |
e6252c3e | 5792 | DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); |
10e2f1ac | 5793 | DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); |
6f505b16 | 5794 | |
1da177e4 LT |
5795 | void __init sched_init(void) |
5796 | { | |
dd41f596 | 5797 | int i, j; |
434d53b0 MT |
5798 | unsigned long alloc_size = 0, ptr; |
5799 | ||
9881b024 | 5800 | sched_clock_init(); |
5822a454 | 5801 | wait_bit_init(); |
9dcb8b68 | 5802 | |
434d53b0 MT |
5803 | #ifdef CONFIG_FAIR_GROUP_SCHED |
5804 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5805 | #endif | |
5806 | #ifdef CONFIG_RT_GROUP_SCHED | |
5807 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5808 | #endif | |
434d53b0 | 5809 | if (alloc_size) { |
36b7b6d4 | 5810 | ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); |
434d53b0 MT |
5811 | |
5812 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
07e06b01 | 5813 | root_task_group.se = (struct sched_entity **)ptr; |
434d53b0 MT |
5814 | ptr += nr_cpu_ids * sizeof(void **); |
5815 | ||
07e06b01 | 5816 | root_task_group.cfs_rq = (struct cfs_rq **)ptr; |
434d53b0 | 5817 | ptr += nr_cpu_ids * sizeof(void **); |
eff766a6 | 5818 | |
6d6bc0ad | 5819 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
434d53b0 | 5820 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5821 | root_task_group.rt_se = (struct sched_rt_entity **)ptr; |
434d53b0 MT |
5822 | ptr += nr_cpu_ids * sizeof(void **); |
5823 | ||
07e06b01 | 5824 | root_task_group.rt_rq = (struct rt_rq **)ptr; |
eff766a6 PZ |
5825 | ptr += nr_cpu_ids * sizeof(void **); |
5826 | ||
6d6bc0ad | 5827 | #endif /* CONFIG_RT_GROUP_SCHED */ |
b74e6278 | 5828 | } |
df7c8e84 | 5829 | #ifdef CONFIG_CPUMASK_OFFSTACK |
b74e6278 AT |
5830 | for_each_possible_cpu(i) { |
5831 | per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( | |
5832 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
10e2f1ac PZ |
5833 | per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( |
5834 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
434d53b0 | 5835 | } |
b74e6278 | 5836 | #endif /* CONFIG_CPUMASK_OFFSTACK */ |
dd41f596 | 5837 | |
d1ccc66d IM |
5838 | init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); |
5839 | init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime()); | |
332ac17e | 5840 | |
57d885fe GH |
5841 | #ifdef CONFIG_SMP |
5842 | init_defrootdomain(); | |
5843 | #endif | |
5844 | ||
d0b27fa7 | 5845 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5846 | init_rt_bandwidth(&root_task_group.rt_bandwidth, |
d0b27fa7 | 5847 | global_rt_period(), global_rt_runtime()); |
6d6bc0ad | 5848 | #endif /* CONFIG_RT_GROUP_SCHED */ |
d0b27fa7 | 5849 | |
7c941438 | 5850 | #ifdef CONFIG_CGROUP_SCHED |
b0367629 WL |
5851 | task_group_cache = KMEM_CACHE(task_group, 0); |
5852 | ||
07e06b01 YZ |
5853 | list_add(&root_task_group.list, &task_groups); |
5854 | INIT_LIST_HEAD(&root_task_group.children); | |
f4d6f6c2 | 5855 | INIT_LIST_HEAD(&root_task_group.siblings); |
5091faa4 | 5856 | autogroup_init(&init_task); |
7c941438 | 5857 | #endif /* CONFIG_CGROUP_SCHED */ |
6f505b16 | 5858 | |
0a945022 | 5859 | for_each_possible_cpu(i) { |
70b97a7f | 5860 | struct rq *rq; |
1da177e4 LT |
5861 | |
5862 | rq = cpu_rq(i); | |
05fa785c | 5863 | raw_spin_lock_init(&rq->lock); |
7897986b | 5864 | rq->nr_running = 0; |
dce48a84 TG |
5865 | rq->calc_load_active = 0; |
5866 | rq->calc_load_update = jiffies + LOAD_FREQ; | |
acb5a9ba | 5867 | init_cfs_rq(&rq->cfs); |
07c54f7a AV |
5868 | init_rt_rq(&rq->rt); |
5869 | init_dl_rq(&rq->dl); | |
dd41f596 | 5870 | #ifdef CONFIG_FAIR_GROUP_SCHED |
029632fb | 5871 | root_task_group.shares = ROOT_TASK_GROUP_LOAD; |
6f505b16 | 5872 | INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); |
9c2791f9 | 5873 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; |
354d60c2 | 5874 | /* |
d1ccc66d | 5875 | * How much CPU bandwidth does root_task_group get? |
354d60c2 DG |
5876 | * |
5877 | * In case of task-groups formed thr' the cgroup filesystem, it | |
d1ccc66d IM |
5878 | * gets 100% of the CPU resources in the system. This overall |
5879 | * system CPU resource is divided among the tasks of | |
07e06b01 | 5880 | * root_task_group and its child task-groups in a fair manner, |
354d60c2 DG |
5881 | * based on each entity's (task or task-group's) weight |
5882 | * (se->load.weight). | |
5883 | * | |
07e06b01 | 5884 | * In other words, if root_task_group has 10 tasks of weight |
354d60c2 | 5885 | * 1024) and two child groups A0 and A1 (of weight 1024 each), |
d1ccc66d | 5886 | * then A0's share of the CPU resource is: |
354d60c2 | 5887 | * |
0d905bca | 5888 | * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% |
354d60c2 | 5889 | * |
07e06b01 YZ |
5890 | * We achieve this by letting root_task_group's tasks sit |
5891 | * directly in rq->cfs (i.e root_task_group->se[] = NULL). | |
354d60c2 | 5892 | */ |
ab84d31e | 5893 | init_cfs_bandwidth(&root_task_group.cfs_bandwidth); |
07e06b01 | 5894 | init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); |
354d60c2 DG |
5895 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
5896 | ||
5897 | rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; | |
052f1dc7 | 5898 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5899 | init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); |
dd41f596 | 5900 | #endif |
1da177e4 | 5901 | |
dd41f596 IM |
5902 | for (j = 0; j < CPU_LOAD_IDX_MAX; j++) |
5903 | rq->cpu_load[j] = 0; | |
fdf3e95d | 5904 | |
1da177e4 | 5905 | #ifdef CONFIG_SMP |
41c7ce9a | 5906 | rq->sd = NULL; |
57d885fe | 5907 | rq->rd = NULL; |
ca6d75e6 | 5908 | rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; |
e3fca9e7 | 5909 | rq->balance_callback = NULL; |
1da177e4 | 5910 | rq->active_balance = 0; |
dd41f596 | 5911 | rq->next_balance = jiffies; |
1da177e4 | 5912 | rq->push_cpu = 0; |
0a2966b4 | 5913 | rq->cpu = i; |
1f11eb6a | 5914 | rq->online = 0; |
eae0c9df MG |
5915 | rq->idle_stamp = 0; |
5916 | rq->avg_idle = 2*sysctl_sched_migration_cost; | |
9bd721c5 | 5917 | rq->max_idle_balance_cost = sysctl_sched_migration_cost; |
367456c7 PZ |
5918 | |
5919 | INIT_LIST_HEAD(&rq->cfs_tasks); | |
5920 | ||
dc938520 | 5921 | rq_attach_root(rq, &def_root_domain); |
3451d024 | 5922 | #ifdef CONFIG_NO_HZ_COMMON |
9fd81dd5 | 5923 | rq->last_load_update_tick = jiffies; |
1c792db7 | 5924 | rq->nohz_flags = 0; |
83cd4fe2 | 5925 | #endif |
265f22a9 FW |
5926 | #ifdef CONFIG_NO_HZ_FULL |
5927 | rq->last_sched_tick = 0; | |
5928 | #endif | |
9fd81dd5 | 5929 | #endif /* CONFIG_SMP */ |
8f4d37ec | 5930 | init_rq_hrtick(rq); |
1da177e4 | 5931 | atomic_set(&rq->nr_iowait, 0); |
1da177e4 LT |
5932 | } |
5933 | ||
9059393e | 5934 | set_load_weight(&init_task, false); |
b50f60ce | 5935 | |
1da177e4 LT |
5936 | /* |
5937 | * The boot idle thread does lazy MMU switching as well: | |
5938 | */ | |
f1f10076 | 5939 | mmgrab(&init_mm); |
1da177e4 LT |
5940 | enter_lazy_tlb(&init_mm, current); |
5941 | ||
5942 | /* | |
5943 | * Make us the idle thread. Technically, schedule() should not be | |
5944 | * called from this thread, however somewhere below it might be, | |
5945 | * but because we are the idle thread, we just pick up running again | |
5946 | * when this runqueue becomes "idle". | |
5947 | */ | |
5948 | init_idle(current, smp_processor_id()); | |
dce48a84 TG |
5949 | |
5950 | calc_load_update = jiffies + LOAD_FREQ; | |
5951 | ||
bf4d83f6 | 5952 | #ifdef CONFIG_SMP |
29d5e047 | 5953 | idle_thread_set_boot_cpu(); |
9cf7243d | 5954 | set_cpu_rq_start_time(smp_processor_id()); |
029632fb PZ |
5955 | #endif |
5956 | init_sched_fair_class(); | |
6a7b3dc3 | 5957 | |
4698f88c JP |
5958 | init_schedstats(); |
5959 | ||
6892b75e | 5960 | scheduler_running = 1; |
1da177e4 LT |
5961 | } |
5962 | ||
d902db1e | 5963 | #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
e4aafea2 FW |
5964 | static inline int preempt_count_equals(int preempt_offset) |
5965 | { | |
da7142e2 | 5966 | int nested = preempt_count() + rcu_preempt_depth(); |
e4aafea2 | 5967 | |
4ba8216c | 5968 | return (nested == preempt_offset); |
e4aafea2 FW |
5969 | } |
5970 | ||
d894837f | 5971 | void __might_sleep(const char *file, int line, int preempt_offset) |
1da177e4 | 5972 | { |
8eb23b9f PZ |
5973 | /* |
5974 | * Blocking primitives will set (and therefore destroy) current->state, | |
5975 | * since we will exit with TASK_RUNNING make sure we enter with it, | |
5976 | * otherwise we will destroy state. | |
5977 | */ | |
00845eb9 | 5978 | WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, |
8eb23b9f PZ |
5979 | "do not call blocking ops when !TASK_RUNNING; " |
5980 | "state=%lx set at [<%p>] %pS\n", | |
5981 | current->state, | |
5982 | (void *)current->task_state_change, | |
00845eb9 | 5983 | (void *)current->task_state_change); |
8eb23b9f | 5984 | |
3427445a PZ |
5985 | ___might_sleep(file, line, preempt_offset); |
5986 | } | |
5987 | EXPORT_SYMBOL(__might_sleep); | |
5988 | ||
5989 | void ___might_sleep(const char *file, int line, int preempt_offset) | |
1da177e4 | 5990 | { |
d1ccc66d IM |
5991 | /* Ratelimiting timestamp: */ |
5992 | static unsigned long prev_jiffy; | |
5993 | ||
d1c6d149 | 5994 | unsigned long preempt_disable_ip; |
1da177e4 | 5995 | |
d1ccc66d IM |
5996 | /* WARN_ON_ONCE() by default, no rate limit required: */ |
5997 | rcu_sleep_check(); | |
5998 | ||
db273be2 TG |
5999 | if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && |
6000 | !is_idle_task(current)) || | |
1c3c5eab TG |
6001 | system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || |
6002 | oops_in_progress) | |
aef745fc | 6003 | return; |
1c3c5eab | 6004 | |
aef745fc IM |
6005 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) |
6006 | return; | |
6007 | prev_jiffy = jiffies; | |
6008 | ||
d1ccc66d | 6009 | /* Save this before calling printk(), since that will clobber it: */ |
d1c6d149 VN |
6010 | preempt_disable_ip = get_preempt_disable_ip(current); |
6011 | ||
3df0fc5b PZ |
6012 | printk(KERN_ERR |
6013 | "BUG: sleeping function called from invalid context at %s:%d\n", | |
6014 | file, line); | |
6015 | printk(KERN_ERR | |
6016 | "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", | |
6017 | in_atomic(), irqs_disabled(), | |
6018 | current->pid, current->comm); | |
aef745fc | 6019 | |
a8b686b3 ES |
6020 | if (task_stack_end_corrupted(current)) |
6021 | printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); | |
6022 | ||
aef745fc IM |
6023 | debug_show_held_locks(current); |
6024 | if (irqs_disabled()) | |
6025 | print_irqtrace_events(current); | |
d1c6d149 VN |
6026 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
6027 | && !preempt_count_equals(preempt_offset)) { | |
8f47b187 | 6028 | pr_err("Preemption disabled at:"); |
d1c6d149 | 6029 | print_ip_sym(preempt_disable_ip); |
8f47b187 TG |
6030 | pr_cont("\n"); |
6031 | } | |
aef745fc | 6032 | dump_stack(); |
f0b22e39 | 6033 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
1da177e4 | 6034 | } |
3427445a | 6035 | EXPORT_SYMBOL(___might_sleep); |
1da177e4 LT |
6036 | #endif |
6037 | ||
6038 | #ifdef CONFIG_MAGIC_SYSRQ | |
dbc7f069 | 6039 | void normalize_rt_tasks(void) |
3a5e4dc1 | 6040 | { |
dbc7f069 | 6041 | struct task_struct *g, *p; |
d50dde5a DF |
6042 | struct sched_attr attr = { |
6043 | .sched_policy = SCHED_NORMAL, | |
6044 | }; | |
1da177e4 | 6045 | |
3472eaa1 | 6046 | read_lock(&tasklist_lock); |
5d07f420 | 6047 | for_each_process_thread(g, p) { |
178be793 IM |
6048 | /* |
6049 | * Only normalize user tasks: | |
6050 | */ | |
3472eaa1 | 6051 | if (p->flags & PF_KTHREAD) |
178be793 IM |
6052 | continue; |
6053 | ||
4fa8d299 JP |
6054 | p->se.exec_start = 0; |
6055 | schedstat_set(p->se.statistics.wait_start, 0); | |
6056 | schedstat_set(p->se.statistics.sleep_start, 0); | |
6057 | schedstat_set(p->se.statistics.block_start, 0); | |
dd41f596 | 6058 | |
aab03e05 | 6059 | if (!dl_task(p) && !rt_task(p)) { |
dd41f596 IM |
6060 | /* |
6061 | * Renice negative nice level userspace | |
6062 | * tasks back to 0: | |
6063 | */ | |
3472eaa1 | 6064 | if (task_nice(p) < 0) |
dd41f596 | 6065 | set_user_nice(p, 0); |
1da177e4 | 6066 | continue; |
dd41f596 | 6067 | } |
1da177e4 | 6068 | |
dbc7f069 | 6069 | __sched_setscheduler(p, &attr, false, false); |
5d07f420 | 6070 | } |
3472eaa1 | 6071 | read_unlock(&tasklist_lock); |
1da177e4 LT |
6072 | } |
6073 | ||
6074 | #endif /* CONFIG_MAGIC_SYSRQ */ | |
1df5c10a | 6075 | |
67fc4e0c | 6076 | #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) |
1df5c10a | 6077 | /* |
67fc4e0c | 6078 | * These functions are only useful for the IA64 MCA handling, or kdb. |
1df5c10a LT |
6079 | * |
6080 | * They can only be called when the whole system has been | |
6081 | * stopped - every CPU needs to be quiescent, and no scheduling | |
6082 | * activity can take place. Using them for anything else would | |
6083 | * be a serious bug, and as a result, they aren't even visible | |
6084 | * under any other configuration. | |
6085 | */ | |
6086 | ||
6087 | /** | |
d1ccc66d | 6088 | * curr_task - return the current task for a given CPU. |
1df5c10a LT |
6089 | * @cpu: the processor in question. |
6090 | * | |
6091 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
e69f6186 YB |
6092 | * |
6093 | * Return: The current task for @cpu. | |
1df5c10a | 6094 | */ |
36c8b586 | 6095 | struct task_struct *curr_task(int cpu) |
1df5c10a LT |
6096 | { |
6097 | return cpu_curr(cpu); | |
6098 | } | |
6099 | ||
67fc4e0c JW |
6100 | #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ |
6101 | ||
6102 | #ifdef CONFIG_IA64 | |
1df5c10a | 6103 | /** |
d1ccc66d | 6104 | * set_curr_task - set the current task for a given CPU. |
1df5c10a LT |
6105 | * @cpu: the processor in question. |
6106 | * @p: the task pointer to set. | |
6107 | * | |
6108 | * Description: This function must only be used when non-maskable interrupts | |
41a2d6cf | 6109 | * are serviced on a separate stack. It allows the architecture to switch the |
d1ccc66d | 6110 | * notion of the current task on a CPU in a non-blocking manner. This function |
1df5c10a LT |
6111 | * must be called with all CPU's synchronized, and interrupts disabled, the |
6112 | * and caller must save the original value of the current task (see | |
6113 | * curr_task() above) and restore that value before reenabling interrupts and | |
6114 | * re-starting the system. | |
6115 | * | |
6116 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6117 | */ | |
a458ae2e | 6118 | void ia64_set_curr_task(int cpu, struct task_struct *p) |
1df5c10a LT |
6119 | { |
6120 | cpu_curr(cpu) = p; | |
6121 | } | |
6122 | ||
6123 | #endif | |
29f59db3 | 6124 | |
7c941438 | 6125 | #ifdef CONFIG_CGROUP_SCHED |
029632fb PZ |
6126 | /* task_group_lock serializes the addition/removal of task groups */ |
6127 | static DEFINE_SPINLOCK(task_group_lock); | |
6128 | ||
2f5177f0 | 6129 | static void sched_free_group(struct task_group *tg) |
bccbe08a PZ |
6130 | { |
6131 | free_fair_sched_group(tg); | |
6132 | free_rt_sched_group(tg); | |
e9aa1dd1 | 6133 | autogroup_free(tg); |
b0367629 | 6134 | kmem_cache_free(task_group_cache, tg); |
bccbe08a PZ |
6135 | } |
6136 | ||
6137 | /* allocate runqueue etc for a new task group */ | |
ec7dc8ac | 6138 | struct task_group *sched_create_group(struct task_group *parent) |
bccbe08a PZ |
6139 | { |
6140 | struct task_group *tg; | |
bccbe08a | 6141 | |
b0367629 | 6142 | tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); |
bccbe08a PZ |
6143 | if (!tg) |
6144 | return ERR_PTR(-ENOMEM); | |
6145 | ||
ec7dc8ac | 6146 | if (!alloc_fair_sched_group(tg, parent)) |
bccbe08a PZ |
6147 | goto err; |
6148 | ||
ec7dc8ac | 6149 | if (!alloc_rt_sched_group(tg, parent)) |
bccbe08a PZ |
6150 | goto err; |
6151 | ||
ace783b9 LZ |
6152 | return tg; |
6153 | ||
6154 | err: | |
2f5177f0 | 6155 | sched_free_group(tg); |
ace783b9 LZ |
6156 | return ERR_PTR(-ENOMEM); |
6157 | } | |
6158 | ||
6159 | void sched_online_group(struct task_group *tg, struct task_group *parent) | |
6160 | { | |
6161 | unsigned long flags; | |
6162 | ||
8ed36996 | 6163 | spin_lock_irqsave(&task_group_lock, flags); |
6f505b16 | 6164 | list_add_rcu(&tg->list, &task_groups); |
f473aa5e | 6165 | |
d1ccc66d IM |
6166 | /* Root should already exist: */ |
6167 | WARN_ON(!parent); | |
f473aa5e PZ |
6168 | |
6169 | tg->parent = parent; | |
f473aa5e | 6170 | INIT_LIST_HEAD(&tg->children); |
09f2724a | 6171 | list_add_rcu(&tg->siblings, &parent->children); |
8ed36996 | 6172 | spin_unlock_irqrestore(&task_group_lock, flags); |
8663e24d PZ |
6173 | |
6174 | online_fair_sched_group(tg); | |
29f59db3 SV |
6175 | } |
6176 | ||
9b5b7751 | 6177 | /* rcu callback to free various structures associated with a task group */ |
2f5177f0 | 6178 | static void sched_free_group_rcu(struct rcu_head *rhp) |
29f59db3 | 6179 | { |
d1ccc66d | 6180 | /* Now it should be safe to free those cfs_rqs: */ |
2f5177f0 | 6181 | sched_free_group(container_of(rhp, struct task_group, rcu)); |
29f59db3 SV |
6182 | } |
6183 | ||
4cf86d77 | 6184 | void sched_destroy_group(struct task_group *tg) |
ace783b9 | 6185 | { |
d1ccc66d | 6186 | /* Wait for possible concurrent references to cfs_rqs complete: */ |
2f5177f0 | 6187 | call_rcu(&tg->rcu, sched_free_group_rcu); |
ace783b9 LZ |
6188 | } |
6189 | ||
6190 | void sched_offline_group(struct task_group *tg) | |
29f59db3 | 6191 | { |
8ed36996 | 6192 | unsigned long flags; |
29f59db3 | 6193 | |
d1ccc66d | 6194 | /* End participation in shares distribution: */ |
6fe1f348 | 6195 | unregister_fair_sched_group(tg); |
3d4b47b4 PZ |
6196 | |
6197 | spin_lock_irqsave(&task_group_lock, flags); | |
6f505b16 | 6198 | list_del_rcu(&tg->list); |
f473aa5e | 6199 | list_del_rcu(&tg->siblings); |
8ed36996 | 6200 | spin_unlock_irqrestore(&task_group_lock, flags); |
29f59db3 SV |
6201 | } |
6202 | ||
ea86cb4b | 6203 | static void sched_change_group(struct task_struct *tsk, int type) |
29f59db3 | 6204 | { |
8323f26c | 6205 | struct task_group *tg; |
29f59db3 | 6206 | |
f7b8a47d KT |
6207 | /* |
6208 | * All callers are synchronized by task_rq_lock(); we do not use RCU | |
6209 | * which is pointless here. Thus, we pass "true" to task_css_check() | |
6210 | * to prevent lockdep warnings. | |
6211 | */ | |
6212 | tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), | |
8323f26c PZ |
6213 | struct task_group, css); |
6214 | tg = autogroup_task_group(tsk, tg); | |
6215 | tsk->sched_task_group = tg; | |
6216 | ||
810b3817 | 6217 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b VG |
6218 | if (tsk->sched_class->task_change_group) |
6219 | tsk->sched_class->task_change_group(tsk, type); | |
b2b5ce02 | 6220 | else |
810b3817 | 6221 | #endif |
b2b5ce02 | 6222 | set_task_rq(tsk, task_cpu(tsk)); |
ea86cb4b VG |
6223 | } |
6224 | ||
6225 | /* | |
6226 | * Change task's runqueue when it moves between groups. | |
6227 | * | |
6228 | * The caller of this function should have put the task in its new group by | |
6229 | * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect | |
6230 | * its new group. | |
6231 | */ | |
6232 | void sched_move_task(struct task_struct *tsk) | |
6233 | { | |
7a57f32a PZ |
6234 | int queued, running, queue_flags = |
6235 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; | |
ea86cb4b VG |
6236 | struct rq_flags rf; |
6237 | struct rq *rq; | |
6238 | ||
6239 | rq = task_rq_lock(tsk, &rf); | |
1b1d6225 | 6240 | update_rq_clock(rq); |
ea86cb4b VG |
6241 | |
6242 | running = task_current(rq, tsk); | |
6243 | queued = task_on_rq_queued(tsk); | |
6244 | ||
6245 | if (queued) | |
7a57f32a | 6246 | dequeue_task(rq, tsk, queue_flags); |
bb3bac2c | 6247 | if (running) |
ea86cb4b VG |
6248 | put_prev_task(rq, tsk); |
6249 | ||
6250 | sched_change_group(tsk, TASK_MOVE_GROUP); | |
810b3817 | 6251 | |
da0c1e65 | 6252 | if (queued) |
7a57f32a | 6253 | enqueue_task(rq, tsk, queue_flags); |
bb3bac2c | 6254 | if (running) |
b2bf6c31 | 6255 | set_curr_task(rq, tsk); |
29f59db3 | 6256 | |
eb580751 | 6257 | task_rq_unlock(rq, tsk, &rf); |
29f59db3 | 6258 | } |
68318b8e | 6259 | |
a7c6d554 | 6260 | static inline struct task_group *css_tg(struct cgroup_subsys_state *css) |
68318b8e | 6261 | { |
a7c6d554 | 6262 | return css ? container_of(css, struct task_group, css) : NULL; |
68318b8e SV |
6263 | } |
6264 | ||
eb95419b TH |
6265 | static struct cgroup_subsys_state * |
6266 | cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) | |
68318b8e | 6267 | { |
eb95419b TH |
6268 | struct task_group *parent = css_tg(parent_css); |
6269 | struct task_group *tg; | |
68318b8e | 6270 | |
eb95419b | 6271 | if (!parent) { |
68318b8e | 6272 | /* This is early initialization for the top cgroup */ |
07e06b01 | 6273 | return &root_task_group.css; |
68318b8e SV |
6274 | } |
6275 | ||
ec7dc8ac | 6276 | tg = sched_create_group(parent); |
68318b8e SV |
6277 | if (IS_ERR(tg)) |
6278 | return ERR_PTR(-ENOMEM); | |
6279 | ||
68318b8e SV |
6280 | return &tg->css; |
6281 | } | |
6282 | ||
96b77745 KK |
6283 | /* Expose task group only after completing cgroup initialization */ |
6284 | static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) | |
6285 | { | |
6286 | struct task_group *tg = css_tg(css); | |
6287 | struct task_group *parent = css_tg(css->parent); | |
6288 | ||
6289 | if (parent) | |
6290 | sched_online_group(tg, parent); | |
6291 | return 0; | |
6292 | } | |
6293 | ||
2f5177f0 | 6294 | static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) |
ace783b9 | 6295 | { |
eb95419b | 6296 | struct task_group *tg = css_tg(css); |
ace783b9 | 6297 | |
2f5177f0 | 6298 | sched_offline_group(tg); |
ace783b9 LZ |
6299 | } |
6300 | ||
eb95419b | 6301 | static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) |
68318b8e | 6302 | { |
eb95419b | 6303 | struct task_group *tg = css_tg(css); |
68318b8e | 6304 | |
2f5177f0 PZ |
6305 | /* |
6306 | * Relies on the RCU grace period between css_released() and this. | |
6307 | */ | |
6308 | sched_free_group(tg); | |
ace783b9 LZ |
6309 | } |
6310 | ||
ea86cb4b VG |
6311 | /* |
6312 | * This is called before wake_up_new_task(), therefore we really only | |
6313 | * have to set its group bits, all the other stuff does not apply. | |
6314 | */ | |
b53202e6 | 6315 | static void cpu_cgroup_fork(struct task_struct *task) |
eeb61e53 | 6316 | { |
ea86cb4b VG |
6317 | struct rq_flags rf; |
6318 | struct rq *rq; | |
6319 | ||
6320 | rq = task_rq_lock(task, &rf); | |
6321 | ||
80f5c1b8 | 6322 | update_rq_clock(rq); |
ea86cb4b VG |
6323 | sched_change_group(task, TASK_SET_GROUP); |
6324 | ||
6325 | task_rq_unlock(rq, task, &rf); | |
eeb61e53 KT |
6326 | } |
6327 | ||
1f7dd3e5 | 6328 | static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) |
68318b8e | 6329 | { |
bb9d97b6 | 6330 | struct task_struct *task; |
1f7dd3e5 | 6331 | struct cgroup_subsys_state *css; |
7dc603c9 | 6332 | int ret = 0; |
bb9d97b6 | 6333 | |
1f7dd3e5 | 6334 | cgroup_taskset_for_each(task, css, tset) { |
b68aa230 | 6335 | #ifdef CONFIG_RT_GROUP_SCHED |
eb95419b | 6336 | if (!sched_rt_can_attach(css_tg(css), task)) |
bb9d97b6 | 6337 | return -EINVAL; |
b68aa230 | 6338 | #else |
bb9d97b6 TH |
6339 | /* We don't support RT-tasks being in separate groups */ |
6340 | if (task->sched_class != &fair_sched_class) | |
6341 | return -EINVAL; | |
b68aa230 | 6342 | #endif |
7dc603c9 PZ |
6343 | /* |
6344 | * Serialize against wake_up_new_task() such that if its | |
6345 | * running, we're sure to observe its full state. | |
6346 | */ | |
6347 | raw_spin_lock_irq(&task->pi_lock); | |
6348 | /* | |
6349 | * Avoid calling sched_move_task() before wake_up_new_task() | |
6350 | * has happened. This would lead to problems with PELT, due to | |
6351 | * move wanting to detach+attach while we're not attached yet. | |
6352 | */ | |
6353 | if (task->state == TASK_NEW) | |
6354 | ret = -EINVAL; | |
6355 | raw_spin_unlock_irq(&task->pi_lock); | |
6356 | ||
6357 | if (ret) | |
6358 | break; | |
bb9d97b6 | 6359 | } |
7dc603c9 | 6360 | return ret; |
be367d09 | 6361 | } |
68318b8e | 6362 | |
1f7dd3e5 | 6363 | static void cpu_cgroup_attach(struct cgroup_taskset *tset) |
68318b8e | 6364 | { |
bb9d97b6 | 6365 | struct task_struct *task; |
1f7dd3e5 | 6366 | struct cgroup_subsys_state *css; |
bb9d97b6 | 6367 | |
1f7dd3e5 | 6368 | cgroup_taskset_for_each(task, css, tset) |
bb9d97b6 | 6369 | sched_move_task(task); |
68318b8e SV |
6370 | } |
6371 | ||
052f1dc7 | 6372 | #ifdef CONFIG_FAIR_GROUP_SCHED |
182446d0 TH |
6373 | static int cpu_shares_write_u64(struct cgroup_subsys_state *css, |
6374 | struct cftype *cftype, u64 shareval) | |
68318b8e | 6375 | { |
182446d0 | 6376 | return sched_group_set_shares(css_tg(css), scale_load(shareval)); |
68318b8e SV |
6377 | } |
6378 | ||
182446d0 TH |
6379 | static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, |
6380 | struct cftype *cft) | |
68318b8e | 6381 | { |
182446d0 | 6382 | struct task_group *tg = css_tg(css); |
68318b8e | 6383 | |
c8b28116 | 6384 | return (u64) scale_load_down(tg->shares); |
68318b8e | 6385 | } |
ab84d31e PT |
6386 | |
6387 | #ifdef CONFIG_CFS_BANDWIDTH | |
a790de99 PT |
6388 | static DEFINE_MUTEX(cfs_constraints_mutex); |
6389 | ||
ab84d31e PT |
6390 | const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ |
6391 | const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ | |
6392 | ||
a790de99 PT |
6393 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); |
6394 | ||
ab84d31e PT |
6395 | static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) |
6396 | { | |
56f570e5 | 6397 | int i, ret = 0, runtime_enabled, runtime_was_enabled; |
029632fb | 6398 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
ab84d31e PT |
6399 | |
6400 | if (tg == &root_task_group) | |
6401 | return -EINVAL; | |
6402 | ||
6403 | /* | |
6404 | * Ensure we have at some amount of bandwidth every period. This is | |
6405 | * to prevent reaching a state of large arrears when throttled via | |
6406 | * entity_tick() resulting in prolonged exit starvation. | |
6407 | */ | |
6408 | if (quota < min_cfs_quota_period || period < min_cfs_quota_period) | |
6409 | return -EINVAL; | |
6410 | ||
6411 | /* | |
6412 | * Likewise, bound things on the otherside by preventing insane quota | |
6413 | * periods. This also allows us to normalize in computing quota | |
6414 | * feasibility. | |
6415 | */ | |
6416 | if (period > max_cfs_quota_period) | |
6417 | return -EINVAL; | |
6418 | ||
0e59bdae KT |
6419 | /* |
6420 | * Prevent race between setting of cfs_rq->runtime_enabled and | |
6421 | * unthrottle_offline_cfs_rqs(). | |
6422 | */ | |
6423 | get_online_cpus(); | |
a790de99 PT |
6424 | mutex_lock(&cfs_constraints_mutex); |
6425 | ret = __cfs_schedulable(tg, period, quota); | |
6426 | if (ret) | |
6427 | goto out_unlock; | |
6428 | ||
58088ad0 | 6429 | runtime_enabled = quota != RUNTIME_INF; |
56f570e5 | 6430 | runtime_was_enabled = cfs_b->quota != RUNTIME_INF; |
1ee14e6c BS |
6431 | /* |
6432 | * If we need to toggle cfs_bandwidth_used, off->on must occur | |
6433 | * before making related changes, and on->off must occur afterwards | |
6434 | */ | |
6435 | if (runtime_enabled && !runtime_was_enabled) | |
6436 | cfs_bandwidth_usage_inc(); | |
ab84d31e PT |
6437 | raw_spin_lock_irq(&cfs_b->lock); |
6438 | cfs_b->period = ns_to_ktime(period); | |
6439 | cfs_b->quota = quota; | |
58088ad0 | 6440 | |
a9cf55b2 | 6441 | __refill_cfs_bandwidth_runtime(cfs_b); |
d1ccc66d IM |
6442 | |
6443 | /* Restart the period timer (if active) to handle new period expiry: */ | |
77a4d1a1 PZ |
6444 | if (runtime_enabled) |
6445 | start_cfs_bandwidth(cfs_b); | |
d1ccc66d | 6446 | |
ab84d31e PT |
6447 | raw_spin_unlock_irq(&cfs_b->lock); |
6448 | ||
0e59bdae | 6449 | for_each_online_cpu(i) { |
ab84d31e | 6450 | struct cfs_rq *cfs_rq = tg->cfs_rq[i]; |
029632fb | 6451 | struct rq *rq = cfs_rq->rq; |
8a8c69c3 | 6452 | struct rq_flags rf; |
ab84d31e | 6453 | |
8a8c69c3 | 6454 | rq_lock_irq(rq, &rf); |
58088ad0 | 6455 | cfs_rq->runtime_enabled = runtime_enabled; |
ab84d31e | 6456 | cfs_rq->runtime_remaining = 0; |
671fd9da | 6457 | |
029632fb | 6458 | if (cfs_rq->throttled) |
671fd9da | 6459 | unthrottle_cfs_rq(cfs_rq); |
8a8c69c3 | 6460 | rq_unlock_irq(rq, &rf); |
ab84d31e | 6461 | } |
1ee14e6c BS |
6462 | if (runtime_was_enabled && !runtime_enabled) |
6463 | cfs_bandwidth_usage_dec(); | |
a790de99 PT |
6464 | out_unlock: |
6465 | mutex_unlock(&cfs_constraints_mutex); | |
0e59bdae | 6466 | put_online_cpus(); |
ab84d31e | 6467 | |
a790de99 | 6468 | return ret; |
ab84d31e PT |
6469 | } |
6470 | ||
6471 | int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) | |
6472 | { | |
6473 | u64 quota, period; | |
6474 | ||
029632fb | 6475 | period = ktime_to_ns(tg->cfs_bandwidth.period); |
ab84d31e PT |
6476 | if (cfs_quota_us < 0) |
6477 | quota = RUNTIME_INF; | |
6478 | else | |
6479 | quota = (u64)cfs_quota_us * NSEC_PER_USEC; | |
6480 | ||
6481 | return tg_set_cfs_bandwidth(tg, period, quota); | |
6482 | } | |
6483 | ||
6484 | long tg_get_cfs_quota(struct task_group *tg) | |
6485 | { | |
6486 | u64 quota_us; | |
6487 | ||
029632fb | 6488 | if (tg->cfs_bandwidth.quota == RUNTIME_INF) |
ab84d31e PT |
6489 | return -1; |
6490 | ||
029632fb | 6491 | quota_us = tg->cfs_bandwidth.quota; |
ab84d31e PT |
6492 | do_div(quota_us, NSEC_PER_USEC); |
6493 | ||
6494 | return quota_us; | |
6495 | } | |
6496 | ||
6497 | int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) | |
6498 | { | |
6499 | u64 quota, period; | |
6500 | ||
6501 | period = (u64)cfs_period_us * NSEC_PER_USEC; | |
029632fb | 6502 | quota = tg->cfs_bandwidth.quota; |
ab84d31e | 6503 | |
ab84d31e PT |
6504 | return tg_set_cfs_bandwidth(tg, period, quota); |
6505 | } | |
6506 | ||
6507 | long tg_get_cfs_period(struct task_group *tg) | |
6508 | { | |
6509 | u64 cfs_period_us; | |
6510 | ||
029632fb | 6511 | cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); |
ab84d31e PT |
6512 | do_div(cfs_period_us, NSEC_PER_USEC); |
6513 | ||
6514 | return cfs_period_us; | |
6515 | } | |
6516 | ||
182446d0 TH |
6517 | static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, |
6518 | struct cftype *cft) | |
ab84d31e | 6519 | { |
182446d0 | 6520 | return tg_get_cfs_quota(css_tg(css)); |
ab84d31e PT |
6521 | } |
6522 | ||
182446d0 TH |
6523 | static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, |
6524 | struct cftype *cftype, s64 cfs_quota_us) | |
ab84d31e | 6525 | { |
182446d0 | 6526 | return tg_set_cfs_quota(css_tg(css), cfs_quota_us); |
ab84d31e PT |
6527 | } |
6528 | ||
182446d0 TH |
6529 | static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, |
6530 | struct cftype *cft) | |
ab84d31e | 6531 | { |
182446d0 | 6532 | return tg_get_cfs_period(css_tg(css)); |
ab84d31e PT |
6533 | } |
6534 | ||
182446d0 TH |
6535 | static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, |
6536 | struct cftype *cftype, u64 cfs_period_us) | |
ab84d31e | 6537 | { |
182446d0 | 6538 | return tg_set_cfs_period(css_tg(css), cfs_period_us); |
ab84d31e PT |
6539 | } |
6540 | ||
a790de99 PT |
6541 | struct cfs_schedulable_data { |
6542 | struct task_group *tg; | |
6543 | u64 period, quota; | |
6544 | }; | |
6545 | ||
6546 | /* | |
6547 | * normalize group quota/period to be quota/max_period | |
6548 | * note: units are usecs | |
6549 | */ | |
6550 | static u64 normalize_cfs_quota(struct task_group *tg, | |
6551 | struct cfs_schedulable_data *d) | |
6552 | { | |
6553 | u64 quota, period; | |
6554 | ||
6555 | if (tg == d->tg) { | |
6556 | period = d->period; | |
6557 | quota = d->quota; | |
6558 | } else { | |
6559 | period = tg_get_cfs_period(tg); | |
6560 | quota = tg_get_cfs_quota(tg); | |
6561 | } | |
6562 | ||
6563 | /* note: these should typically be equivalent */ | |
6564 | if (quota == RUNTIME_INF || quota == -1) | |
6565 | return RUNTIME_INF; | |
6566 | ||
6567 | return to_ratio(period, quota); | |
6568 | } | |
6569 | ||
6570 | static int tg_cfs_schedulable_down(struct task_group *tg, void *data) | |
6571 | { | |
6572 | struct cfs_schedulable_data *d = data; | |
029632fb | 6573 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
a790de99 PT |
6574 | s64 quota = 0, parent_quota = -1; |
6575 | ||
6576 | if (!tg->parent) { | |
6577 | quota = RUNTIME_INF; | |
6578 | } else { | |
029632fb | 6579 | struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; |
a790de99 PT |
6580 | |
6581 | quota = normalize_cfs_quota(tg, d); | |
9c58c79a | 6582 | parent_quota = parent_b->hierarchical_quota; |
a790de99 PT |
6583 | |
6584 | /* | |
d1ccc66d IM |
6585 | * Ensure max(child_quota) <= parent_quota, inherit when no |
6586 | * limit is set: | |
a790de99 PT |
6587 | */ |
6588 | if (quota == RUNTIME_INF) | |
6589 | quota = parent_quota; | |
6590 | else if (parent_quota != RUNTIME_INF && quota > parent_quota) | |
6591 | return -EINVAL; | |
6592 | } | |
9c58c79a | 6593 | cfs_b->hierarchical_quota = quota; |
a790de99 PT |
6594 | |
6595 | return 0; | |
6596 | } | |
6597 | ||
6598 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) | |
6599 | { | |
8277434e | 6600 | int ret; |
a790de99 PT |
6601 | struct cfs_schedulable_data data = { |
6602 | .tg = tg, | |
6603 | .period = period, | |
6604 | .quota = quota, | |
6605 | }; | |
6606 | ||
6607 | if (quota != RUNTIME_INF) { | |
6608 | do_div(data.period, NSEC_PER_USEC); | |
6609 | do_div(data.quota, NSEC_PER_USEC); | |
6610 | } | |
6611 | ||
8277434e PT |
6612 | rcu_read_lock(); |
6613 | ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); | |
6614 | rcu_read_unlock(); | |
6615 | ||
6616 | return ret; | |
a790de99 | 6617 | } |
e8da1b18 | 6618 | |
2da8ca82 | 6619 | static int cpu_stats_show(struct seq_file *sf, void *v) |
e8da1b18 | 6620 | { |
2da8ca82 | 6621 | struct task_group *tg = css_tg(seq_css(sf)); |
029632fb | 6622 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
e8da1b18 | 6623 | |
44ffc75b TH |
6624 | seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); |
6625 | seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); | |
6626 | seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); | |
e8da1b18 NR |
6627 | |
6628 | return 0; | |
6629 | } | |
ab84d31e | 6630 | #endif /* CONFIG_CFS_BANDWIDTH */ |
6d6bc0ad | 6631 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
68318b8e | 6632 | |
052f1dc7 | 6633 | #ifdef CONFIG_RT_GROUP_SCHED |
182446d0 TH |
6634 | static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, |
6635 | struct cftype *cft, s64 val) | |
6f505b16 | 6636 | { |
182446d0 | 6637 | return sched_group_set_rt_runtime(css_tg(css), val); |
6f505b16 PZ |
6638 | } |
6639 | ||
182446d0 TH |
6640 | static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, |
6641 | struct cftype *cft) | |
6f505b16 | 6642 | { |
182446d0 | 6643 | return sched_group_rt_runtime(css_tg(css)); |
6f505b16 | 6644 | } |
d0b27fa7 | 6645 | |
182446d0 TH |
6646 | static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, |
6647 | struct cftype *cftype, u64 rt_period_us) | |
d0b27fa7 | 6648 | { |
182446d0 | 6649 | return sched_group_set_rt_period(css_tg(css), rt_period_us); |
d0b27fa7 PZ |
6650 | } |
6651 | ||
182446d0 TH |
6652 | static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, |
6653 | struct cftype *cft) | |
d0b27fa7 | 6654 | { |
182446d0 | 6655 | return sched_group_rt_period(css_tg(css)); |
d0b27fa7 | 6656 | } |
6d6bc0ad | 6657 | #endif /* CONFIG_RT_GROUP_SCHED */ |
6f505b16 | 6658 | |
fe5c7cc2 | 6659 | static struct cftype cpu_files[] = { |
052f1dc7 | 6660 | #ifdef CONFIG_FAIR_GROUP_SCHED |
fe5c7cc2 PM |
6661 | { |
6662 | .name = "shares", | |
f4c753b7 PM |
6663 | .read_u64 = cpu_shares_read_u64, |
6664 | .write_u64 = cpu_shares_write_u64, | |
fe5c7cc2 | 6665 | }, |
052f1dc7 | 6666 | #endif |
ab84d31e PT |
6667 | #ifdef CONFIG_CFS_BANDWIDTH |
6668 | { | |
6669 | .name = "cfs_quota_us", | |
6670 | .read_s64 = cpu_cfs_quota_read_s64, | |
6671 | .write_s64 = cpu_cfs_quota_write_s64, | |
6672 | }, | |
6673 | { | |
6674 | .name = "cfs_period_us", | |
6675 | .read_u64 = cpu_cfs_period_read_u64, | |
6676 | .write_u64 = cpu_cfs_period_write_u64, | |
6677 | }, | |
e8da1b18 NR |
6678 | { |
6679 | .name = "stat", | |
2da8ca82 | 6680 | .seq_show = cpu_stats_show, |
e8da1b18 | 6681 | }, |
ab84d31e | 6682 | #endif |
052f1dc7 | 6683 | #ifdef CONFIG_RT_GROUP_SCHED |
6f505b16 | 6684 | { |
9f0c1e56 | 6685 | .name = "rt_runtime_us", |
06ecb27c PM |
6686 | .read_s64 = cpu_rt_runtime_read, |
6687 | .write_s64 = cpu_rt_runtime_write, | |
6f505b16 | 6688 | }, |
d0b27fa7 PZ |
6689 | { |
6690 | .name = "rt_period_us", | |
f4c753b7 PM |
6691 | .read_u64 = cpu_rt_period_read_uint, |
6692 | .write_u64 = cpu_rt_period_write_uint, | |
d0b27fa7 | 6693 | }, |
052f1dc7 | 6694 | #endif |
d1ccc66d | 6695 | { } /* Terminate */ |
68318b8e SV |
6696 | }; |
6697 | ||
073219e9 | 6698 | struct cgroup_subsys cpu_cgrp_subsys = { |
92fb9748 | 6699 | .css_alloc = cpu_cgroup_css_alloc, |
96b77745 | 6700 | .css_online = cpu_cgroup_css_online, |
2f5177f0 | 6701 | .css_released = cpu_cgroup_css_released, |
92fb9748 | 6702 | .css_free = cpu_cgroup_css_free, |
eeb61e53 | 6703 | .fork = cpu_cgroup_fork, |
bb9d97b6 TH |
6704 | .can_attach = cpu_cgroup_can_attach, |
6705 | .attach = cpu_cgroup_attach, | |
5577964e | 6706 | .legacy_cftypes = cpu_files, |
b38e42e9 | 6707 | .early_init = true, |
68318b8e SV |
6708 | }; |
6709 | ||
052f1dc7 | 6710 | #endif /* CONFIG_CGROUP_SCHED */ |
d842de87 | 6711 | |
b637a328 PM |
6712 | void dump_cpu_task(int cpu) |
6713 | { | |
6714 | pr_info("Task dump for CPU %d:\n", cpu); | |
6715 | sched_show_task(cpu_curr(cpu)); | |
6716 | } | |
ed82b8a1 AK |
6717 | |
6718 | /* | |
6719 | * Nice levels are multiplicative, with a gentle 10% change for every | |
6720 | * nice level changed. I.e. when a CPU-bound task goes from nice 0 to | |
6721 | * nice 1, it will get ~10% less CPU time than another CPU-bound task | |
6722 | * that remained on nice 0. | |
6723 | * | |
6724 | * The "10% effect" is relative and cumulative: from _any_ nice level, | |
6725 | * if you go up 1 level, it's -10% CPU usage, if you go down 1 level | |
6726 | * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. | |
6727 | * If a task goes up by ~10% and another task goes down by ~10% then | |
6728 | * the relative distance between them is ~25%.) | |
6729 | */ | |
6730 | const int sched_prio_to_weight[40] = { | |
6731 | /* -20 */ 88761, 71755, 56483, 46273, 36291, | |
6732 | /* -15 */ 29154, 23254, 18705, 14949, 11916, | |
6733 | /* -10 */ 9548, 7620, 6100, 4904, 3906, | |
6734 | /* -5 */ 3121, 2501, 1991, 1586, 1277, | |
6735 | /* 0 */ 1024, 820, 655, 526, 423, | |
6736 | /* 5 */ 335, 272, 215, 172, 137, | |
6737 | /* 10 */ 110, 87, 70, 56, 45, | |
6738 | /* 15 */ 36, 29, 23, 18, 15, | |
6739 | }; | |
6740 | ||
6741 | /* | |
6742 | * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. | |
6743 | * | |
6744 | * In cases where the weight does not change often, we can use the | |
6745 | * precalculated inverse to speed up arithmetics by turning divisions | |
6746 | * into multiplications: | |
6747 | */ | |
6748 | const u32 sched_prio_to_wmult[40] = { | |
6749 | /* -20 */ 48388, 59856, 76040, 92818, 118348, | |
6750 | /* -15 */ 147320, 184698, 229616, 287308, 360437, | |
6751 | /* -10 */ 449829, 563644, 704093, 875809, 1099582, | |
6752 | /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, | |
6753 | /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, | |
6754 | /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, | |
6755 | /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, | |
6756 | /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, | |
6757 | }; |