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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> | |
1da177e4 | 29 | |
96f951ed | 30 | #include <asm/switch_to.h> |
5517d86b | 31 | #include <asm/tlb.h> |
fd4a61e0 MB |
32 | #ifdef CONFIG_PARAVIRT |
33 | #include <asm/paravirt.h> | |
34 | #endif | |
1da177e4 | 35 | |
029632fb | 36 | #include "sched.h" |
ea138446 | 37 | #include "../workqueue_internal.h" |
29d5e047 | 38 | #include "../smpboot.h" |
6e0534f2 | 39 | |
a8d154b0 | 40 | #define CREATE_TRACE_POINTS |
ad8d75ff | 41 | #include <trace/events/sched.h> |
a8d154b0 | 42 | |
029632fb | 43 | DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); |
dc61b1d6 | 44 | |
bf5c91ba IM |
45 | /* |
46 | * Debugging: various feature bits | |
47 | */ | |
f00b45c1 | 48 | |
f00b45c1 PZ |
49 | #define SCHED_FEAT(name, enabled) \ |
50 | (1UL << __SCHED_FEAT_##name) * enabled | | |
51 | ||
bf5c91ba | 52 | const_debug unsigned int sysctl_sched_features = |
391e43da | 53 | #include "features.h" |
f00b45c1 PZ |
54 | 0; |
55 | ||
56 | #undef SCHED_FEAT | |
57 | ||
b82d9fdd PZ |
58 | /* |
59 | * Number of tasks to iterate in a single balance run. | |
60 | * Limited because this is done with IRQs disabled. | |
61 | */ | |
62 | const_debug unsigned int sysctl_sched_nr_migrate = 32; | |
63 | ||
e9e9250b PZ |
64 | /* |
65 | * period over which we average the RT time consumption, measured | |
66 | * in ms. | |
67 | * | |
68 | * default: 1s | |
69 | */ | |
70 | const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; | |
71 | ||
fa85ae24 | 72 | /* |
d1ccc66d | 73 | * period over which we measure -rt task CPU usage in us. |
fa85ae24 PZ |
74 | * default: 1s |
75 | */ | |
9f0c1e56 | 76 | unsigned int sysctl_sched_rt_period = 1000000; |
fa85ae24 | 77 | |
029632fb | 78 | __read_mostly int scheduler_running; |
6892b75e | 79 | |
9f0c1e56 PZ |
80 | /* |
81 | * part of the period that we allow rt tasks to run in us. | |
82 | * default: 0.95s | |
83 | */ | |
84 | int sysctl_sched_rt_runtime = 950000; | |
fa85ae24 | 85 | |
d1ccc66d | 86 | /* CPUs with isolated domains */ |
3fa0818b RR |
87 | cpumask_var_t cpu_isolated_map; |
88 | ||
3e71a462 PZ |
89 | /* |
90 | * __task_rq_lock - lock the rq @p resides on. | |
91 | */ | |
eb580751 | 92 | struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
3e71a462 PZ |
93 | __acquires(rq->lock) |
94 | { | |
95 | struct rq *rq; | |
96 | ||
97 | lockdep_assert_held(&p->pi_lock); | |
98 | ||
99 | for (;;) { | |
100 | rq = task_rq(p); | |
101 | raw_spin_lock(&rq->lock); | |
102 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
d8ac8971 | 103 | rq_pin_lock(rq, rf); |
3e71a462 PZ |
104 | return rq; |
105 | } | |
106 | raw_spin_unlock(&rq->lock); | |
107 | ||
108 | while (unlikely(task_on_rq_migrating(p))) | |
109 | cpu_relax(); | |
110 | } | |
111 | } | |
112 | ||
113 | /* | |
114 | * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. | |
115 | */ | |
eb580751 | 116 | struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf) |
3e71a462 PZ |
117 | __acquires(p->pi_lock) |
118 | __acquires(rq->lock) | |
119 | { | |
120 | struct rq *rq; | |
121 | ||
122 | for (;;) { | |
eb580751 | 123 | raw_spin_lock_irqsave(&p->pi_lock, rf->flags); |
3e71a462 PZ |
124 | rq = task_rq(p); |
125 | raw_spin_lock(&rq->lock); | |
126 | /* | |
127 | * move_queued_task() task_rq_lock() | |
128 | * | |
129 | * ACQUIRE (rq->lock) | |
130 | * [S] ->on_rq = MIGRATING [L] rq = task_rq() | |
131 | * WMB (__set_task_cpu()) ACQUIRE (rq->lock); | |
132 | * [S] ->cpu = new_cpu [L] task_rq() | |
133 | * [L] ->on_rq | |
134 | * RELEASE (rq->lock) | |
135 | * | |
136 | * If we observe the old cpu in task_rq_lock, the acquire of | |
137 | * the old rq->lock will fully serialize against the stores. | |
138 | * | |
d1ccc66d | 139 | * If we observe the new CPU in task_rq_lock, the acquire will |
3e71a462 PZ |
140 | * pair with the WMB to ensure we must then also see migrating. |
141 | */ | |
142 | if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) { | |
d8ac8971 | 143 | rq_pin_lock(rq, rf); |
3e71a462 PZ |
144 | return rq; |
145 | } | |
146 | raw_spin_unlock(&rq->lock); | |
eb580751 | 147 | raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags); |
3e71a462 PZ |
148 | |
149 | while (unlikely(task_on_rq_migrating(p))) | |
150 | cpu_relax(); | |
151 | } | |
152 | } | |
153 | ||
535b9552 IM |
154 | /* |
155 | * RQ-clock updating methods: | |
156 | */ | |
157 | ||
158 | static void update_rq_clock_task(struct rq *rq, s64 delta) | |
159 | { | |
160 | /* | |
161 | * In theory, the compile should just see 0 here, and optimize out the call | |
162 | * to sched_rt_avg_update. But I don't trust it... | |
163 | */ | |
164 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
165 | s64 steal = 0, irq_delta = 0; | |
166 | #endif | |
167 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING | |
168 | irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; | |
169 | ||
170 | /* | |
171 | * Since irq_time is only updated on {soft,}irq_exit, we might run into | |
172 | * this case when a previous update_rq_clock() happened inside a | |
173 | * {soft,}irq region. | |
174 | * | |
175 | * When this happens, we stop ->clock_task and only update the | |
176 | * prev_irq_time stamp to account for the part that fit, so that a next | |
177 | * update will consume the rest. This ensures ->clock_task is | |
178 | * monotonic. | |
179 | * | |
180 | * It does however cause some slight miss-attribution of {soft,}irq | |
181 | * time, a more accurate solution would be to update the irq_time using | |
182 | * the current rq->clock timestamp, except that would require using | |
183 | * atomic ops. | |
184 | */ | |
185 | if (irq_delta > delta) | |
186 | irq_delta = delta; | |
187 | ||
188 | rq->prev_irq_time += irq_delta; | |
189 | delta -= irq_delta; | |
190 | #endif | |
191 | #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING | |
192 | if (static_key_false((¶virt_steal_rq_enabled))) { | |
193 | steal = paravirt_steal_clock(cpu_of(rq)); | |
194 | steal -= rq->prev_steal_time_rq; | |
195 | ||
196 | if (unlikely(steal > delta)) | |
197 | steal = delta; | |
198 | ||
199 | rq->prev_steal_time_rq += steal; | |
200 | delta -= steal; | |
201 | } | |
202 | #endif | |
203 | ||
204 | rq->clock_task += delta; | |
205 | ||
206 | #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) | |
207 | if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY)) | |
208 | sched_rt_avg_update(rq, irq_delta + steal); | |
209 | #endif | |
210 | } | |
211 | ||
212 | void update_rq_clock(struct rq *rq) | |
213 | { | |
214 | s64 delta; | |
215 | ||
216 | lockdep_assert_held(&rq->lock); | |
217 | ||
218 | if (rq->clock_update_flags & RQCF_ACT_SKIP) | |
219 | return; | |
220 | ||
221 | #ifdef CONFIG_SCHED_DEBUG | |
26ae58d2 PZ |
222 | if (sched_feat(WARN_DOUBLE_CLOCK)) |
223 | SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); | |
535b9552 IM |
224 | rq->clock_update_flags |= RQCF_UPDATED; |
225 | #endif | |
26ae58d2 | 226 | |
535b9552 IM |
227 | delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; |
228 | if (delta < 0) | |
229 | return; | |
230 | rq->clock += delta; | |
231 | update_rq_clock_task(rq, delta); | |
232 | } | |
233 | ||
234 | ||
8f4d37ec PZ |
235 | #ifdef CONFIG_SCHED_HRTICK |
236 | /* | |
237 | * Use HR-timers to deliver accurate preemption points. | |
8f4d37ec | 238 | */ |
8f4d37ec | 239 | |
8f4d37ec PZ |
240 | static void hrtick_clear(struct rq *rq) |
241 | { | |
242 | if (hrtimer_active(&rq->hrtick_timer)) | |
243 | hrtimer_cancel(&rq->hrtick_timer); | |
244 | } | |
245 | ||
8f4d37ec PZ |
246 | /* |
247 | * High-resolution timer tick. | |
248 | * Runs from hardirq context with interrupts disabled. | |
249 | */ | |
250 | static enum hrtimer_restart hrtick(struct hrtimer *timer) | |
251 | { | |
252 | struct rq *rq = container_of(timer, struct rq, hrtick_timer); | |
8a8c69c3 | 253 | struct rq_flags rf; |
8f4d37ec PZ |
254 | |
255 | WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); | |
256 | ||
8a8c69c3 | 257 | rq_lock(rq, &rf); |
3e51f33f | 258 | update_rq_clock(rq); |
8f4d37ec | 259 | rq->curr->sched_class->task_tick(rq, rq->curr, 1); |
8a8c69c3 | 260 | rq_unlock(rq, &rf); |
8f4d37ec PZ |
261 | |
262 | return HRTIMER_NORESTART; | |
263 | } | |
264 | ||
95e904c7 | 265 | #ifdef CONFIG_SMP |
971ee28c | 266 | |
4961b6e1 | 267 | static void __hrtick_restart(struct rq *rq) |
971ee28c PZ |
268 | { |
269 | struct hrtimer *timer = &rq->hrtick_timer; | |
971ee28c | 270 | |
4961b6e1 | 271 | hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED); |
971ee28c PZ |
272 | } |
273 | ||
31656519 PZ |
274 | /* |
275 | * called from hardirq (IPI) context | |
276 | */ | |
277 | static void __hrtick_start(void *arg) | |
b328ca18 | 278 | { |
31656519 | 279 | struct rq *rq = arg; |
8a8c69c3 | 280 | struct rq_flags rf; |
b328ca18 | 281 | |
8a8c69c3 | 282 | rq_lock(rq, &rf); |
971ee28c | 283 | __hrtick_restart(rq); |
31656519 | 284 | rq->hrtick_csd_pending = 0; |
8a8c69c3 | 285 | rq_unlock(rq, &rf); |
b328ca18 PZ |
286 | } |
287 | ||
31656519 PZ |
288 | /* |
289 | * Called to set the hrtick timer state. | |
290 | * | |
291 | * called with rq->lock held and irqs disabled | |
292 | */ | |
029632fb | 293 | void hrtick_start(struct rq *rq, u64 delay) |
b328ca18 | 294 | { |
31656519 | 295 | struct hrtimer *timer = &rq->hrtick_timer; |
177ef2a6 | 296 | ktime_t time; |
297 | s64 delta; | |
298 | ||
299 | /* | |
300 | * Don't schedule slices shorter than 10000ns, that just | |
301 | * doesn't make sense and can cause timer DoS. | |
302 | */ | |
303 | delta = max_t(s64, delay, 10000LL); | |
304 | time = ktime_add_ns(timer->base->get_time(), delta); | |
b328ca18 | 305 | |
cc584b21 | 306 | hrtimer_set_expires(timer, time); |
31656519 PZ |
307 | |
308 | if (rq == this_rq()) { | |
971ee28c | 309 | __hrtick_restart(rq); |
31656519 | 310 | } else if (!rq->hrtick_csd_pending) { |
c46fff2a | 311 | smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd); |
31656519 PZ |
312 | rq->hrtick_csd_pending = 1; |
313 | } | |
b328ca18 PZ |
314 | } |
315 | ||
31656519 PZ |
316 | #else |
317 | /* | |
318 | * Called to set the hrtick timer state. | |
319 | * | |
320 | * called with rq->lock held and irqs disabled | |
321 | */ | |
029632fb | 322 | void hrtick_start(struct rq *rq, u64 delay) |
31656519 | 323 | { |
86893335 WL |
324 | /* |
325 | * Don't schedule slices shorter than 10000ns, that just | |
326 | * doesn't make sense. Rely on vruntime for fairness. | |
327 | */ | |
328 | delay = max_t(u64, delay, 10000LL); | |
4961b6e1 TG |
329 | hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay), |
330 | HRTIMER_MODE_REL_PINNED); | |
31656519 | 331 | } |
31656519 | 332 | #endif /* CONFIG_SMP */ |
8f4d37ec | 333 | |
31656519 | 334 | static void init_rq_hrtick(struct rq *rq) |
8f4d37ec | 335 | { |
31656519 PZ |
336 | #ifdef CONFIG_SMP |
337 | rq->hrtick_csd_pending = 0; | |
8f4d37ec | 338 | |
31656519 PZ |
339 | rq->hrtick_csd.flags = 0; |
340 | rq->hrtick_csd.func = __hrtick_start; | |
341 | rq->hrtick_csd.info = rq; | |
342 | #endif | |
8f4d37ec | 343 | |
31656519 PZ |
344 | hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
345 | rq->hrtick_timer.function = hrtick; | |
8f4d37ec | 346 | } |
006c75f1 | 347 | #else /* CONFIG_SCHED_HRTICK */ |
8f4d37ec PZ |
348 | static inline void hrtick_clear(struct rq *rq) |
349 | { | |
350 | } | |
351 | ||
8f4d37ec PZ |
352 | static inline void init_rq_hrtick(struct rq *rq) |
353 | { | |
354 | } | |
006c75f1 | 355 | #endif /* CONFIG_SCHED_HRTICK */ |
8f4d37ec | 356 | |
5529578a FW |
357 | /* |
358 | * cmpxchg based fetch_or, macro so it works for different integer types | |
359 | */ | |
360 | #define fetch_or(ptr, mask) \ | |
361 | ({ \ | |
362 | typeof(ptr) _ptr = (ptr); \ | |
363 | typeof(mask) _mask = (mask); \ | |
364 | typeof(*_ptr) _old, _val = *_ptr; \ | |
365 | \ | |
366 | for (;;) { \ | |
367 | _old = cmpxchg(_ptr, _val, _val | _mask); \ | |
368 | if (_old == _val) \ | |
369 | break; \ | |
370 | _val = _old; \ | |
371 | } \ | |
372 | _old; \ | |
373 | }) | |
374 | ||
e3baac47 | 375 | #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) |
fd99f91a PZ |
376 | /* |
377 | * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, | |
378 | * this avoids any races wrt polling state changes and thereby avoids | |
379 | * spurious IPIs. | |
380 | */ | |
381 | static bool set_nr_and_not_polling(struct task_struct *p) | |
382 | { | |
383 | struct thread_info *ti = task_thread_info(p); | |
384 | return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG); | |
385 | } | |
e3baac47 PZ |
386 | |
387 | /* | |
388 | * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set. | |
389 | * | |
390 | * If this returns true, then the idle task promises to call | |
391 | * sched_ttwu_pending() and reschedule soon. | |
392 | */ | |
393 | static bool set_nr_if_polling(struct task_struct *p) | |
394 | { | |
395 | struct thread_info *ti = task_thread_info(p); | |
316c1608 | 396 | typeof(ti->flags) old, val = READ_ONCE(ti->flags); |
e3baac47 PZ |
397 | |
398 | for (;;) { | |
399 | if (!(val & _TIF_POLLING_NRFLAG)) | |
400 | return false; | |
401 | if (val & _TIF_NEED_RESCHED) | |
402 | return true; | |
403 | old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED); | |
404 | if (old == val) | |
405 | break; | |
406 | val = old; | |
407 | } | |
408 | return true; | |
409 | } | |
410 | ||
fd99f91a PZ |
411 | #else |
412 | static bool set_nr_and_not_polling(struct task_struct *p) | |
413 | { | |
414 | set_tsk_need_resched(p); | |
415 | return true; | |
416 | } | |
e3baac47 PZ |
417 | |
418 | #ifdef CONFIG_SMP | |
419 | static bool set_nr_if_polling(struct task_struct *p) | |
420 | { | |
421 | return false; | |
422 | } | |
423 | #endif | |
fd99f91a PZ |
424 | #endif |
425 | ||
76751049 PZ |
426 | void wake_q_add(struct wake_q_head *head, struct task_struct *task) |
427 | { | |
428 | struct wake_q_node *node = &task->wake_q; | |
429 | ||
430 | /* | |
431 | * Atomically grab the task, if ->wake_q is !nil already it means | |
432 | * its already queued (either by us or someone else) and will get the | |
433 | * wakeup due to that. | |
434 | * | |
435 | * This cmpxchg() implies a full barrier, which pairs with the write | |
58fe9c46 | 436 | * barrier implied by the wakeup in wake_up_q(). |
76751049 PZ |
437 | */ |
438 | if (cmpxchg(&node->next, NULL, WAKE_Q_TAIL)) | |
439 | return; | |
440 | ||
441 | get_task_struct(task); | |
442 | ||
443 | /* | |
444 | * The head is context local, there can be no concurrency. | |
445 | */ | |
446 | *head->lastp = node; | |
447 | head->lastp = &node->next; | |
448 | } | |
449 | ||
450 | void wake_up_q(struct wake_q_head *head) | |
451 | { | |
452 | struct wake_q_node *node = head->first; | |
453 | ||
454 | while (node != WAKE_Q_TAIL) { | |
455 | struct task_struct *task; | |
456 | ||
457 | task = container_of(node, struct task_struct, wake_q); | |
458 | BUG_ON(!task); | |
d1ccc66d | 459 | /* Task can safely be re-inserted now: */ |
76751049 PZ |
460 | node = node->next; |
461 | task->wake_q.next = NULL; | |
462 | ||
463 | /* | |
464 | * wake_up_process() implies a wmb() to pair with the queueing | |
465 | * in wake_q_add() so as not to miss wakeups. | |
466 | */ | |
467 | wake_up_process(task); | |
468 | put_task_struct(task); | |
469 | } | |
470 | } | |
471 | ||
c24d20db | 472 | /* |
8875125e | 473 | * resched_curr - mark rq's current task 'to be rescheduled now'. |
c24d20db IM |
474 | * |
475 | * On UP this means the setting of the need_resched flag, on SMP it | |
476 | * might also involve a cross-CPU call to trigger the scheduler on | |
477 | * the target CPU. | |
478 | */ | |
8875125e | 479 | void resched_curr(struct rq *rq) |
c24d20db | 480 | { |
8875125e | 481 | struct task_struct *curr = rq->curr; |
c24d20db IM |
482 | int cpu; |
483 | ||
8875125e | 484 | lockdep_assert_held(&rq->lock); |
c24d20db | 485 | |
8875125e | 486 | if (test_tsk_need_resched(curr)) |
c24d20db IM |
487 | return; |
488 | ||
8875125e | 489 | cpu = cpu_of(rq); |
fd99f91a | 490 | |
f27dde8d | 491 | if (cpu == smp_processor_id()) { |
8875125e | 492 | set_tsk_need_resched(curr); |
f27dde8d | 493 | set_preempt_need_resched(); |
c24d20db | 494 | return; |
f27dde8d | 495 | } |
c24d20db | 496 | |
8875125e | 497 | if (set_nr_and_not_polling(curr)) |
c24d20db | 498 | smp_send_reschedule(cpu); |
dfc68f29 AL |
499 | else |
500 | trace_sched_wake_idle_without_ipi(cpu); | |
c24d20db IM |
501 | } |
502 | ||
029632fb | 503 | void resched_cpu(int cpu) |
c24d20db IM |
504 | { |
505 | struct rq *rq = cpu_rq(cpu); | |
506 | unsigned long flags; | |
507 | ||
05fa785c | 508 | if (!raw_spin_trylock_irqsave(&rq->lock, flags)) |
c24d20db | 509 | return; |
8875125e | 510 | resched_curr(rq); |
05fa785c | 511 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
c24d20db | 512 | } |
06d8308c | 513 | |
b021fe3e | 514 | #ifdef CONFIG_SMP |
3451d024 | 515 | #ifdef CONFIG_NO_HZ_COMMON |
83cd4fe2 | 516 | /* |
d1ccc66d IM |
517 | * In the semi idle case, use the nearest busy CPU for migrating timers |
518 | * from an idle CPU. This is good for power-savings. | |
83cd4fe2 VP |
519 | * |
520 | * We don't do similar optimization for completely idle system, as | |
d1ccc66d IM |
521 | * selecting an idle CPU will add more delays to the timers than intended |
522 | * (as that CPU's timer base may not be uptodate wrt jiffies etc). | |
83cd4fe2 | 523 | */ |
bc7a34b8 | 524 | int get_nohz_timer_target(void) |
83cd4fe2 | 525 | { |
bc7a34b8 | 526 | int i, cpu = smp_processor_id(); |
83cd4fe2 VP |
527 | struct sched_domain *sd; |
528 | ||
9642d18e | 529 | if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu)) |
6201b4d6 VK |
530 | return cpu; |
531 | ||
057f3fad | 532 | rcu_read_lock(); |
83cd4fe2 | 533 | for_each_domain(cpu, sd) { |
057f3fad | 534 | for_each_cpu(i, sched_domain_span(sd)) { |
44496922 WL |
535 | if (cpu == i) |
536 | continue; | |
537 | ||
538 | if (!idle_cpu(i) && is_housekeeping_cpu(i)) { | |
057f3fad PZ |
539 | cpu = i; |
540 | goto unlock; | |
541 | } | |
542 | } | |
83cd4fe2 | 543 | } |
9642d18e VH |
544 | |
545 | if (!is_housekeeping_cpu(cpu)) | |
546 | cpu = housekeeping_any_cpu(); | |
057f3fad PZ |
547 | unlock: |
548 | rcu_read_unlock(); | |
83cd4fe2 VP |
549 | return cpu; |
550 | } | |
d1ccc66d | 551 | |
06d8308c TG |
552 | /* |
553 | * When add_timer_on() enqueues a timer into the timer wheel of an | |
554 | * idle CPU then this timer might expire before the next timer event | |
555 | * which is scheduled to wake up that CPU. In case of a completely | |
556 | * idle system the next event might even be infinite time into the | |
557 | * future. wake_up_idle_cpu() ensures that the CPU is woken up and | |
558 | * leaves the inner idle loop so the newly added timer is taken into | |
559 | * account when the CPU goes back to idle and evaluates the timer | |
560 | * wheel for the next timer event. | |
561 | */ | |
1c20091e | 562 | static void wake_up_idle_cpu(int cpu) |
06d8308c TG |
563 | { |
564 | struct rq *rq = cpu_rq(cpu); | |
565 | ||
566 | if (cpu == smp_processor_id()) | |
567 | return; | |
568 | ||
67b9ca70 | 569 | if (set_nr_and_not_polling(rq->idle)) |
06d8308c | 570 | smp_send_reschedule(cpu); |
dfc68f29 AL |
571 | else |
572 | trace_sched_wake_idle_without_ipi(cpu); | |
45bf76df IM |
573 | } |
574 | ||
c5bfece2 | 575 | static bool wake_up_full_nohz_cpu(int cpu) |
1c20091e | 576 | { |
53c5fa16 FW |
577 | /* |
578 | * We just need the target to call irq_exit() and re-evaluate | |
579 | * the next tick. The nohz full kick at least implies that. | |
580 | * If needed we can still optimize that later with an | |
581 | * empty IRQ. | |
582 | */ | |
379d9ecb PM |
583 | if (cpu_is_offline(cpu)) |
584 | return true; /* Don't try to wake offline CPUs. */ | |
c5bfece2 | 585 | if (tick_nohz_full_cpu(cpu)) { |
1c20091e FW |
586 | if (cpu != smp_processor_id() || |
587 | tick_nohz_tick_stopped()) | |
53c5fa16 | 588 | tick_nohz_full_kick_cpu(cpu); |
1c20091e FW |
589 | return true; |
590 | } | |
591 | ||
592 | return false; | |
593 | } | |
594 | ||
379d9ecb PM |
595 | /* |
596 | * Wake up the specified CPU. If the CPU is going offline, it is the | |
597 | * caller's responsibility to deal with the lost wakeup, for example, | |
598 | * by hooking into the CPU_DEAD notifier like timers and hrtimers do. | |
599 | */ | |
1c20091e FW |
600 | void wake_up_nohz_cpu(int cpu) |
601 | { | |
c5bfece2 | 602 | if (!wake_up_full_nohz_cpu(cpu)) |
1c20091e FW |
603 | wake_up_idle_cpu(cpu); |
604 | } | |
605 | ||
ca38062e | 606 | static inline bool got_nohz_idle_kick(void) |
45bf76df | 607 | { |
1c792db7 | 608 | int cpu = smp_processor_id(); |
873b4c65 VG |
609 | |
610 | if (!test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu))) | |
611 | return false; | |
612 | ||
613 | if (idle_cpu(cpu) && !need_resched()) | |
614 | return true; | |
615 | ||
616 | /* | |
617 | * We can't run Idle Load Balance on this CPU for this time so we | |
618 | * cancel it and clear NOHZ_BALANCE_KICK | |
619 | */ | |
620 | clear_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); | |
621 | return false; | |
45bf76df IM |
622 | } |
623 | ||
3451d024 | 624 | #else /* CONFIG_NO_HZ_COMMON */ |
45bf76df | 625 | |
ca38062e | 626 | static inline bool got_nohz_idle_kick(void) |
2069dd75 | 627 | { |
ca38062e | 628 | return false; |
2069dd75 PZ |
629 | } |
630 | ||
3451d024 | 631 | #endif /* CONFIG_NO_HZ_COMMON */ |
d842de87 | 632 | |
ce831b38 | 633 | #ifdef CONFIG_NO_HZ_FULL |
76d92ac3 | 634 | bool sched_can_stop_tick(struct rq *rq) |
ce831b38 | 635 | { |
76d92ac3 FW |
636 | int fifo_nr_running; |
637 | ||
638 | /* Deadline tasks, even if single, need the tick */ | |
639 | if (rq->dl.dl_nr_running) | |
640 | return false; | |
641 | ||
1e78cdbd | 642 | /* |
2548d546 PZ |
643 | * If there are more than one RR tasks, we need the tick to effect the |
644 | * actual RR behaviour. | |
1e78cdbd | 645 | */ |
76d92ac3 FW |
646 | if (rq->rt.rr_nr_running) { |
647 | if (rq->rt.rr_nr_running == 1) | |
648 | return true; | |
649 | else | |
650 | return false; | |
1e78cdbd RR |
651 | } |
652 | ||
2548d546 PZ |
653 | /* |
654 | * If there's no RR tasks, but FIFO tasks, we can skip the tick, no | |
655 | * forced preemption between FIFO tasks. | |
656 | */ | |
657 | fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running; | |
658 | if (fifo_nr_running) | |
659 | return true; | |
660 | ||
661 | /* | |
662 | * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left; | |
663 | * if there's more than one we need the tick for involuntary | |
664 | * preemption. | |
665 | */ | |
666 | if (rq->nr_running > 1) | |
541b8264 | 667 | return false; |
ce831b38 | 668 | |
541b8264 | 669 | return true; |
ce831b38 FW |
670 | } |
671 | #endif /* CONFIG_NO_HZ_FULL */ | |
d842de87 | 672 | |
029632fb | 673 | void sched_avg_update(struct rq *rq) |
18d95a28 | 674 | { |
e9e9250b PZ |
675 | s64 period = sched_avg_period(); |
676 | ||
78becc27 | 677 | while ((s64)(rq_clock(rq) - rq->age_stamp) > period) { |
0d98bb26 WD |
678 | /* |
679 | * Inline assembly required to prevent the compiler | |
680 | * optimising this loop into a divmod call. | |
681 | * See __iter_div_u64_rem() for another example of this. | |
682 | */ | |
683 | asm("" : "+rm" (rq->age_stamp)); | |
e9e9250b PZ |
684 | rq->age_stamp += period; |
685 | rq->rt_avg /= 2; | |
686 | } | |
18d95a28 PZ |
687 | } |
688 | ||
6d6bc0ad | 689 | #endif /* CONFIG_SMP */ |
18d95a28 | 690 | |
a790de99 PT |
691 | #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ |
692 | (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) | |
c09595f6 | 693 | /* |
8277434e PT |
694 | * Iterate task_group tree rooted at *from, calling @down when first entering a |
695 | * node and @up when leaving it for the final time. | |
696 | * | |
697 | * Caller must hold rcu_lock or sufficient equivalent. | |
c09595f6 | 698 | */ |
029632fb | 699 | int walk_tg_tree_from(struct task_group *from, |
8277434e | 700 | tg_visitor down, tg_visitor up, void *data) |
c09595f6 PZ |
701 | { |
702 | struct task_group *parent, *child; | |
eb755805 | 703 | int ret; |
c09595f6 | 704 | |
8277434e PT |
705 | parent = from; |
706 | ||
c09595f6 | 707 | down: |
eb755805 PZ |
708 | ret = (*down)(parent, data); |
709 | if (ret) | |
8277434e | 710 | goto out; |
c09595f6 PZ |
711 | list_for_each_entry_rcu(child, &parent->children, siblings) { |
712 | parent = child; | |
713 | goto down; | |
714 | ||
715 | up: | |
716 | continue; | |
717 | } | |
eb755805 | 718 | ret = (*up)(parent, data); |
8277434e PT |
719 | if (ret || parent == from) |
720 | goto out; | |
c09595f6 PZ |
721 | |
722 | child = parent; | |
723 | parent = parent->parent; | |
724 | if (parent) | |
725 | goto up; | |
8277434e | 726 | out: |
eb755805 | 727 | return ret; |
c09595f6 PZ |
728 | } |
729 | ||
029632fb | 730 | int tg_nop(struct task_group *tg, void *data) |
eb755805 | 731 | { |
e2b245f8 | 732 | return 0; |
eb755805 | 733 | } |
18d95a28 PZ |
734 | #endif |
735 | ||
45bf76df IM |
736 | static void set_load_weight(struct task_struct *p) |
737 | { | |
f05998d4 NR |
738 | int prio = p->static_prio - MAX_RT_PRIO; |
739 | struct load_weight *load = &p->se.load; | |
740 | ||
dd41f596 IM |
741 | /* |
742 | * SCHED_IDLE tasks get minimal weight: | |
743 | */ | |
20f9cd2a | 744 | if (idle_policy(p->policy)) { |
c8b28116 | 745 | load->weight = scale_load(WEIGHT_IDLEPRIO); |
f05998d4 | 746 | load->inv_weight = WMULT_IDLEPRIO; |
dd41f596 IM |
747 | return; |
748 | } | |
71f8bd46 | 749 | |
ed82b8a1 AK |
750 | load->weight = scale_load(sched_prio_to_weight[prio]); |
751 | load->inv_weight = sched_prio_to_wmult[prio]; | |
71f8bd46 IM |
752 | } |
753 | ||
1de64443 | 754 | static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags) |
2087a1ad | 755 | { |
0a67d1ee PZ |
756 | if (!(flags & ENQUEUE_NOCLOCK)) |
757 | update_rq_clock(rq); | |
758 | ||
1de64443 PZ |
759 | if (!(flags & ENQUEUE_RESTORE)) |
760 | sched_info_queued(rq, p); | |
0a67d1ee | 761 | |
371fd7e7 | 762 | p->sched_class->enqueue_task(rq, p, flags); |
71f8bd46 IM |
763 | } |
764 | ||
1de64443 | 765 | static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags) |
71f8bd46 | 766 | { |
0a67d1ee PZ |
767 | if (!(flags & DEQUEUE_NOCLOCK)) |
768 | update_rq_clock(rq); | |
769 | ||
1de64443 PZ |
770 | if (!(flags & DEQUEUE_SAVE)) |
771 | sched_info_dequeued(rq, p); | |
0a67d1ee | 772 | |
371fd7e7 | 773 | p->sched_class->dequeue_task(rq, p, flags); |
71f8bd46 IM |
774 | } |
775 | ||
029632fb | 776 | void activate_task(struct rq *rq, struct task_struct *p, int flags) |
1e3c88bd PZ |
777 | { |
778 | if (task_contributes_to_load(p)) | |
779 | rq->nr_uninterruptible--; | |
780 | ||
371fd7e7 | 781 | enqueue_task(rq, p, flags); |
1e3c88bd PZ |
782 | } |
783 | ||
029632fb | 784 | void deactivate_task(struct rq *rq, struct task_struct *p, int flags) |
1e3c88bd PZ |
785 | { |
786 | if (task_contributes_to_load(p)) | |
787 | rq->nr_uninterruptible++; | |
788 | ||
371fd7e7 | 789 | dequeue_task(rq, p, flags); |
1e3c88bd PZ |
790 | } |
791 | ||
14531189 | 792 | /* |
dd41f596 | 793 | * __normal_prio - return the priority that is based on the static prio |
14531189 | 794 | */ |
14531189 IM |
795 | static inline int __normal_prio(struct task_struct *p) |
796 | { | |
dd41f596 | 797 | return p->static_prio; |
14531189 IM |
798 | } |
799 | ||
b29739f9 IM |
800 | /* |
801 | * Calculate the expected normal priority: i.e. priority | |
802 | * without taking RT-inheritance into account. Might be | |
803 | * boosted by interactivity modifiers. Changes upon fork, | |
804 | * setprio syscalls, and whenever the interactivity | |
805 | * estimator recalculates. | |
806 | */ | |
36c8b586 | 807 | static inline int normal_prio(struct task_struct *p) |
b29739f9 IM |
808 | { |
809 | int prio; | |
810 | ||
aab03e05 DF |
811 | if (task_has_dl_policy(p)) |
812 | prio = MAX_DL_PRIO-1; | |
813 | else if (task_has_rt_policy(p)) | |
b29739f9 IM |
814 | prio = MAX_RT_PRIO-1 - p->rt_priority; |
815 | else | |
816 | prio = __normal_prio(p); | |
817 | return prio; | |
818 | } | |
819 | ||
820 | /* | |
821 | * Calculate the current priority, i.e. the priority | |
822 | * taken into account by the scheduler. This value might | |
823 | * be boosted by RT tasks, or might be boosted by | |
824 | * interactivity modifiers. Will be RT if the task got | |
825 | * RT-boosted. If not then it returns p->normal_prio. | |
826 | */ | |
36c8b586 | 827 | static int effective_prio(struct task_struct *p) |
b29739f9 IM |
828 | { |
829 | p->normal_prio = normal_prio(p); | |
830 | /* | |
831 | * If we are RT tasks or we were boosted to RT priority, | |
832 | * keep the priority unchanged. Otherwise, update priority | |
833 | * to the normal priority: | |
834 | */ | |
835 | if (!rt_prio(p->prio)) | |
836 | return p->normal_prio; | |
837 | return p->prio; | |
838 | } | |
839 | ||
1da177e4 LT |
840 | /** |
841 | * task_curr - is this task currently executing on a CPU? | |
842 | * @p: the task in question. | |
e69f6186 YB |
843 | * |
844 | * Return: 1 if the task is currently executing. 0 otherwise. | |
1da177e4 | 845 | */ |
36c8b586 | 846 | inline int task_curr(const struct task_struct *p) |
1da177e4 LT |
847 | { |
848 | return cpu_curr(task_cpu(p)) == p; | |
849 | } | |
850 | ||
67dfa1b7 | 851 | /* |
4c9a4bc8 PZ |
852 | * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock, |
853 | * use the balance_callback list if you want balancing. | |
854 | * | |
855 | * this means any call to check_class_changed() must be followed by a call to | |
856 | * balance_callback(). | |
67dfa1b7 | 857 | */ |
cb469845 SR |
858 | static inline void check_class_changed(struct rq *rq, struct task_struct *p, |
859 | const struct sched_class *prev_class, | |
da7a735e | 860 | int oldprio) |
cb469845 SR |
861 | { |
862 | if (prev_class != p->sched_class) { | |
863 | if (prev_class->switched_from) | |
da7a735e | 864 | prev_class->switched_from(rq, p); |
4c9a4bc8 | 865 | |
da7a735e | 866 | p->sched_class->switched_to(rq, p); |
2d3d891d | 867 | } else if (oldprio != p->prio || dl_task(p)) |
da7a735e | 868 | p->sched_class->prio_changed(rq, p, oldprio); |
cb469845 SR |
869 | } |
870 | ||
029632fb | 871 | void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) |
1e5a7405 PZ |
872 | { |
873 | const struct sched_class *class; | |
874 | ||
875 | if (p->sched_class == rq->curr->sched_class) { | |
876 | rq->curr->sched_class->check_preempt_curr(rq, p, flags); | |
877 | } else { | |
878 | for_each_class(class) { | |
879 | if (class == rq->curr->sched_class) | |
880 | break; | |
881 | if (class == p->sched_class) { | |
8875125e | 882 | resched_curr(rq); |
1e5a7405 PZ |
883 | break; |
884 | } | |
885 | } | |
886 | } | |
887 | ||
888 | /* | |
889 | * A queue event has occurred, and we're going to schedule. In | |
890 | * this case, we can save a useless back to back clock update. | |
891 | */ | |
da0c1e65 | 892 | if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr)) |
9edfbfed | 893 | rq_clock_skip_update(rq, true); |
1e5a7405 PZ |
894 | } |
895 | ||
1da177e4 | 896 | #ifdef CONFIG_SMP |
5cc389bc PZ |
897 | /* |
898 | * This is how migration works: | |
899 | * | |
900 | * 1) we invoke migration_cpu_stop() on the target CPU using | |
901 | * stop_one_cpu(). | |
902 | * 2) stopper starts to run (implicitly forcing the migrated thread | |
903 | * off the CPU) | |
904 | * 3) it checks whether the migrated task is still in the wrong runqueue. | |
905 | * 4) if it's in the wrong runqueue then the migration thread removes | |
906 | * it and puts it into the right queue. | |
907 | * 5) stopper completes and stop_one_cpu() returns and the migration | |
908 | * is done. | |
909 | */ | |
910 | ||
911 | /* | |
912 | * move_queued_task - move a queued task to new rq. | |
913 | * | |
914 | * Returns (locked) new rq. Old rq's lock is released. | |
915 | */ | |
8a8c69c3 PZ |
916 | static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, |
917 | struct task_struct *p, int new_cpu) | |
5cc389bc | 918 | { |
5cc389bc PZ |
919 | lockdep_assert_held(&rq->lock); |
920 | ||
5cc389bc | 921 | p->on_rq = TASK_ON_RQ_MIGRATING; |
15ff991e | 922 | dequeue_task(rq, p, DEQUEUE_NOCLOCK); |
5cc389bc | 923 | set_task_cpu(p, new_cpu); |
8a8c69c3 | 924 | rq_unlock(rq, rf); |
5cc389bc PZ |
925 | |
926 | rq = cpu_rq(new_cpu); | |
927 | ||
8a8c69c3 | 928 | rq_lock(rq, rf); |
5cc389bc | 929 | BUG_ON(task_cpu(p) != new_cpu); |
5cc389bc | 930 | enqueue_task(rq, p, 0); |
3ea94de1 | 931 | p->on_rq = TASK_ON_RQ_QUEUED; |
5cc389bc PZ |
932 | check_preempt_curr(rq, p, 0); |
933 | ||
934 | return rq; | |
935 | } | |
936 | ||
937 | struct migration_arg { | |
938 | struct task_struct *task; | |
939 | int dest_cpu; | |
940 | }; | |
941 | ||
942 | /* | |
d1ccc66d | 943 | * Move (not current) task off this CPU, onto the destination CPU. We're doing |
5cc389bc PZ |
944 | * this because either it can't run here any more (set_cpus_allowed() |
945 | * away from this CPU, or CPU going down), or because we're | |
946 | * attempting to rebalance this task on exec (sched_exec). | |
947 | * | |
948 | * So we race with normal scheduler movements, but that's OK, as long | |
949 | * as the task is no longer on this CPU. | |
5cc389bc | 950 | */ |
8a8c69c3 PZ |
951 | static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, |
952 | struct task_struct *p, int dest_cpu) | |
5cc389bc | 953 | { |
955dbdf4 TH |
954 | if (p->flags & PF_KTHREAD) { |
955 | if (unlikely(!cpu_online(dest_cpu))) | |
956 | return rq; | |
957 | } else { | |
958 | if (unlikely(!cpu_active(dest_cpu))) | |
959 | return rq; | |
960 | } | |
5cc389bc PZ |
961 | |
962 | /* Affinity changed (again). */ | |
0c98d344 | 963 | if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) |
5e16bbc2 | 964 | return rq; |
5cc389bc | 965 | |
15ff991e | 966 | update_rq_clock(rq); |
8a8c69c3 | 967 | rq = move_queued_task(rq, rf, p, dest_cpu); |
5e16bbc2 PZ |
968 | |
969 | return rq; | |
5cc389bc PZ |
970 | } |
971 | ||
972 | /* | |
973 | * migration_cpu_stop - this will be executed by a highprio stopper thread | |
974 | * and performs thread migration by bumping thread off CPU then | |
975 | * 'pushing' onto another runqueue. | |
976 | */ | |
977 | static int migration_cpu_stop(void *data) | |
978 | { | |
979 | struct migration_arg *arg = data; | |
5e16bbc2 PZ |
980 | struct task_struct *p = arg->task; |
981 | struct rq *rq = this_rq(); | |
8a8c69c3 | 982 | struct rq_flags rf; |
5cc389bc PZ |
983 | |
984 | /* | |
d1ccc66d IM |
985 | * The original target CPU might have gone down and we might |
986 | * be on another CPU but it doesn't matter. | |
5cc389bc PZ |
987 | */ |
988 | local_irq_disable(); | |
989 | /* | |
990 | * We need to explicitly wake pending tasks before running | |
991 | * __migrate_task() such that we will not miss enforcing cpus_allowed | |
992 | * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test. | |
993 | */ | |
994 | sched_ttwu_pending(); | |
5e16bbc2 PZ |
995 | |
996 | raw_spin_lock(&p->pi_lock); | |
8a8c69c3 | 997 | rq_lock(rq, &rf); |
5e16bbc2 PZ |
998 | /* |
999 | * If task_rq(p) != rq, it cannot be migrated here, because we're | |
1000 | * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because | |
1001 | * we're holding p->pi_lock. | |
1002 | */ | |
bf89a304 CC |
1003 | if (task_rq(p) == rq) { |
1004 | if (task_on_rq_queued(p)) | |
8a8c69c3 | 1005 | rq = __migrate_task(rq, &rf, p, arg->dest_cpu); |
bf89a304 CC |
1006 | else |
1007 | p->wake_cpu = arg->dest_cpu; | |
1008 | } | |
8a8c69c3 | 1009 | rq_unlock(rq, &rf); |
5e16bbc2 PZ |
1010 | raw_spin_unlock(&p->pi_lock); |
1011 | ||
5cc389bc PZ |
1012 | local_irq_enable(); |
1013 | return 0; | |
1014 | } | |
1015 | ||
c5b28038 PZ |
1016 | /* |
1017 | * sched_class::set_cpus_allowed must do the below, but is not required to | |
1018 | * actually call this function. | |
1019 | */ | |
1020 | void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask) | |
5cc389bc | 1021 | { |
5cc389bc PZ |
1022 | cpumask_copy(&p->cpus_allowed, new_mask); |
1023 | p->nr_cpus_allowed = cpumask_weight(new_mask); | |
1024 | } | |
1025 | ||
c5b28038 PZ |
1026 | void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) |
1027 | { | |
6c37067e PZ |
1028 | struct rq *rq = task_rq(p); |
1029 | bool queued, running; | |
1030 | ||
c5b28038 | 1031 | lockdep_assert_held(&p->pi_lock); |
6c37067e PZ |
1032 | |
1033 | queued = task_on_rq_queued(p); | |
1034 | running = task_current(rq, p); | |
1035 | ||
1036 | if (queued) { | |
1037 | /* | |
1038 | * Because __kthread_bind() calls this on blocked tasks without | |
1039 | * holding rq->lock. | |
1040 | */ | |
1041 | lockdep_assert_held(&rq->lock); | |
7a57f32a | 1042 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
6c37067e PZ |
1043 | } |
1044 | if (running) | |
1045 | put_prev_task(rq, p); | |
1046 | ||
c5b28038 | 1047 | p->sched_class->set_cpus_allowed(p, new_mask); |
6c37067e | 1048 | |
6c37067e | 1049 | if (queued) |
7134b3e9 | 1050 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
a399d233 | 1051 | if (running) |
b2bf6c31 | 1052 | set_curr_task(rq, p); |
c5b28038 PZ |
1053 | } |
1054 | ||
5cc389bc PZ |
1055 | /* |
1056 | * Change a given task's CPU affinity. Migrate the thread to a | |
1057 | * proper CPU and schedule it away if the CPU it's executing on | |
1058 | * is removed from the allowed bitmask. | |
1059 | * | |
1060 | * NOTE: the caller must have a valid reference to the task, the | |
1061 | * task must not exit() & deallocate itself prematurely. The | |
1062 | * call is not atomic; no spinlocks may be held. | |
1063 | */ | |
25834c73 PZ |
1064 | static int __set_cpus_allowed_ptr(struct task_struct *p, |
1065 | const struct cpumask *new_mask, bool check) | |
5cc389bc | 1066 | { |
e9d867a6 | 1067 | const struct cpumask *cpu_valid_mask = cpu_active_mask; |
5cc389bc | 1068 | unsigned int dest_cpu; |
eb580751 PZ |
1069 | struct rq_flags rf; |
1070 | struct rq *rq; | |
5cc389bc PZ |
1071 | int ret = 0; |
1072 | ||
eb580751 | 1073 | rq = task_rq_lock(p, &rf); |
a499c3ea | 1074 | update_rq_clock(rq); |
5cc389bc | 1075 | |
e9d867a6 PZI |
1076 | if (p->flags & PF_KTHREAD) { |
1077 | /* | |
1078 | * Kernel threads are allowed on online && !active CPUs | |
1079 | */ | |
1080 | cpu_valid_mask = cpu_online_mask; | |
1081 | } | |
1082 | ||
25834c73 PZ |
1083 | /* |
1084 | * Must re-check here, to close a race against __kthread_bind(), | |
1085 | * sched_setaffinity() is not guaranteed to observe the flag. | |
1086 | */ | |
1087 | if (check && (p->flags & PF_NO_SETAFFINITY)) { | |
1088 | ret = -EINVAL; | |
1089 | goto out; | |
1090 | } | |
1091 | ||
5cc389bc PZ |
1092 | if (cpumask_equal(&p->cpus_allowed, new_mask)) |
1093 | goto out; | |
1094 | ||
e9d867a6 | 1095 | if (!cpumask_intersects(new_mask, cpu_valid_mask)) { |
5cc389bc PZ |
1096 | ret = -EINVAL; |
1097 | goto out; | |
1098 | } | |
1099 | ||
1100 | do_set_cpus_allowed(p, new_mask); | |
1101 | ||
e9d867a6 PZI |
1102 | if (p->flags & PF_KTHREAD) { |
1103 | /* | |
1104 | * For kernel threads that do indeed end up on online && | |
d1ccc66d | 1105 | * !active we want to ensure they are strict per-CPU threads. |
e9d867a6 PZI |
1106 | */ |
1107 | WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) && | |
1108 | !cpumask_intersects(new_mask, cpu_active_mask) && | |
1109 | p->nr_cpus_allowed != 1); | |
1110 | } | |
1111 | ||
5cc389bc PZ |
1112 | /* Can the task run on the task's current CPU? If so, we're done */ |
1113 | if (cpumask_test_cpu(task_cpu(p), new_mask)) | |
1114 | goto out; | |
1115 | ||
e9d867a6 | 1116 | dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask); |
5cc389bc PZ |
1117 | if (task_running(rq, p) || p->state == TASK_WAKING) { |
1118 | struct migration_arg arg = { p, dest_cpu }; | |
1119 | /* Need help from migration thread: drop lock and wait. */ | |
eb580751 | 1120 | task_rq_unlock(rq, p, &rf); |
5cc389bc PZ |
1121 | stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); |
1122 | tlb_migrate_finish(p->mm); | |
1123 | return 0; | |
cbce1a68 PZ |
1124 | } else if (task_on_rq_queued(p)) { |
1125 | /* | |
1126 | * OK, since we're going to drop the lock immediately | |
1127 | * afterwards anyway. | |
1128 | */ | |
8a8c69c3 | 1129 | rq = move_queued_task(rq, &rf, p, dest_cpu); |
cbce1a68 | 1130 | } |
5cc389bc | 1131 | out: |
eb580751 | 1132 | task_rq_unlock(rq, p, &rf); |
5cc389bc PZ |
1133 | |
1134 | return ret; | |
1135 | } | |
25834c73 PZ |
1136 | |
1137 | int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) | |
1138 | { | |
1139 | return __set_cpus_allowed_ptr(p, new_mask, false); | |
1140 | } | |
5cc389bc PZ |
1141 | EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); |
1142 | ||
dd41f596 | 1143 | void set_task_cpu(struct task_struct *p, unsigned int new_cpu) |
c65cc870 | 1144 | { |
e2912009 PZ |
1145 | #ifdef CONFIG_SCHED_DEBUG |
1146 | /* | |
1147 | * We should never call set_task_cpu() on a blocked task, | |
1148 | * ttwu() will sort out the placement. | |
1149 | */ | |
077614ee | 1150 | WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && |
e2336f6e | 1151 | !p->on_rq); |
0122ec5b | 1152 | |
3ea94de1 JP |
1153 | /* |
1154 | * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING, | |
1155 | * because schedstat_wait_{start,end} rebase migrating task's wait_start | |
1156 | * time relying on p->on_rq. | |
1157 | */ | |
1158 | WARN_ON_ONCE(p->state == TASK_RUNNING && | |
1159 | p->sched_class == &fair_sched_class && | |
1160 | (p->on_rq && !task_on_rq_migrating(p))); | |
1161 | ||
0122ec5b | 1162 | #ifdef CONFIG_LOCKDEP |
6c6c54e1 PZ |
1163 | /* |
1164 | * The caller should hold either p->pi_lock or rq->lock, when changing | |
1165 | * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. | |
1166 | * | |
1167 | * sched_move_task() holds both and thus holding either pins the cgroup, | |
8323f26c | 1168 | * see task_group(). |
6c6c54e1 PZ |
1169 | * |
1170 | * Furthermore, all task_rq users should acquire both locks, see | |
1171 | * task_rq_lock(). | |
1172 | */ | |
0122ec5b PZ |
1173 | WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || |
1174 | lockdep_is_held(&task_rq(p)->lock))); | |
1175 | #endif | |
4ff9083b PZ |
1176 | /* |
1177 | * Clearly, migrating tasks to offline CPUs is a fairly daft thing. | |
1178 | */ | |
1179 | WARN_ON_ONCE(!cpu_online(new_cpu)); | |
e2912009 PZ |
1180 | #endif |
1181 | ||
de1d7286 | 1182 | trace_sched_migrate_task(p, new_cpu); |
cbc34ed1 | 1183 | |
0c69774e | 1184 | if (task_cpu(p) != new_cpu) { |
0a74bef8 | 1185 | if (p->sched_class->migrate_task_rq) |
5a4fd036 | 1186 | p->sched_class->migrate_task_rq(p); |
0c69774e | 1187 | p->se.nr_migrations++; |
ff303e66 | 1188 | perf_event_task_migrate(p); |
0c69774e | 1189 | } |
dd41f596 IM |
1190 | |
1191 | __set_task_cpu(p, new_cpu); | |
c65cc870 IM |
1192 | } |
1193 | ||
ac66f547 PZ |
1194 | static void __migrate_swap_task(struct task_struct *p, int cpu) |
1195 | { | |
da0c1e65 | 1196 | if (task_on_rq_queued(p)) { |
ac66f547 | 1197 | struct rq *src_rq, *dst_rq; |
8a8c69c3 | 1198 | struct rq_flags srf, drf; |
ac66f547 PZ |
1199 | |
1200 | src_rq = task_rq(p); | |
1201 | dst_rq = cpu_rq(cpu); | |
1202 | ||
8a8c69c3 PZ |
1203 | rq_pin_lock(src_rq, &srf); |
1204 | rq_pin_lock(dst_rq, &drf); | |
1205 | ||
3ea94de1 | 1206 | p->on_rq = TASK_ON_RQ_MIGRATING; |
ac66f547 PZ |
1207 | deactivate_task(src_rq, p, 0); |
1208 | set_task_cpu(p, cpu); | |
1209 | activate_task(dst_rq, p, 0); | |
3ea94de1 | 1210 | p->on_rq = TASK_ON_RQ_QUEUED; |
ac66f547 | 1211 | check_preempt_curr(dst_rq, p, 0); |
8a8c69c3 PZ |
1212 | |
1213 | rq_unpin_lock(dst_rq, &drf); | |
1214 | rq_unpin_lock(src_rq, &srf); | |
1215 | ||
ac66f547 PZ |
1216 | } else { |
1217 | /* | |
1218 | * Task isn't running anymore; make it appear like we migrated | |
1219 | * it before it went to sleep. This means on wakeup we make the | |
d1ccc66d | 1220 | * previous CPU our target instead of where it really is. |
ac66f547 PZ |
1221 | */ |
1222 | p->wake_cpu = cpu; | |
1223 | } | |
1224 | } | |
1225 | ||
1226 | struct migration_swap_arg { | |
1227 | struct task_struct *src_task, *dst_task; | |
1228 | int src_cpu, dst_cpu; | |
1229 | }; | |
1230 | ||
1231 | static int migrate_swap_stop(void *data) | |
1232 | { | |
1233 | struct migration_swap_arg *arg = data; | |
1234 | struct rq *src_rq, *dst_rq; | |
1235 | int ret = -EAGAIN; | |
1236 | ||
62694cd5 PZ |
1237 | if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu)) |
1238 | return -EAGAIN; | |
1239 | ||
ac66f547 PZ |
1240 | src_rq = cpu_rq(arg->src_cpu); |
1241 | dst_rq = cpu_rq(arg->dst_cpu); | |
1242 | ||
74602315 PZ |
1243 | double_raw_lock(&arg->src_task->pi_lock, |
1244 | &arg->dst_task->pi_lock); | |
ac66f547 | 1245 | double_rq_lock(src_rq, dst_rq); |
62694cd5 | 1246 | |
ac66f547 PZ |
1247 | if (task_cpu(arg->dst_task) != arg->dst_cpu) |
1248 | goto unlock; | |
1249 | ||
1250 | if (task_cpu(arg->src_task) != arg->src_cpu) | |
1251 | goto unlock; | |
1252 | ||
0c98d344 | 1253 | if (!cpumask_test_cpu(arg->dst_cpu, &arg->src_task->cpus_allowed)) |
ac66f547 PZ |
1254 | goto unlock; |
1255 | ||
0c98d344 | 1256 | if (!cpumask_test_cpu(arg->src_cpu, &arg->dst_task->cpus_allowed)) |
ac66f547 PZ |
1257 | goto unlock; |
1258 | ||
1259 | __migrate_swap_task(arg->src_task, arg->dst_cpu); | |
1260 | __migrate_swap_task(arg->dst_task, arg->src_cpu); | |
1261 | ||
1262 | ret = 0; | |
1263 | ||
1264 | unlock: | |
1265 | double_rq_unlock(src_rq, dst_rq); | |
74602315 PZ |
1266 | raw_spin_unlock(&arg->dst_task->pi_lock); |
1267 | raw_spin_unlock(&arg->src_task->pi_lock); | |
ac66f547 PZ |
1268 | |
1269 | return ret; | |
1270 | } | |
1271 | ||
1272 | /* | |
1273 | * Cross migrate two tasks | |
1274 | */ | |
1275 | int migrate_swap(struct task_struct *cur, struct task_struct *p) | |
1276 | { | |
1277 | struct migration_swap_arg arg; | |
1278 | int ret = -EINVAL; | |
1279 | ||
ac66f547 PZ |
1280 | arg = (struct migration_swap_arg){ |
1281 | .src_task = cur, | |
1282 | .src_cpu = task_cpu(cur), | |
1283 | .dst_task = p, | |
1284 | .dst_cpu = task_cpu(p), | |
1285 | }; | |
1286 | ||
1287 | if (arg.src_cpu == arg.dst_cpu) | |
1288 | goto out; | |
1289 | ||
6acce3ef PZ |
1290 | /* |
1291 | * These three tests are all lockless; this is OK since all of them | |
1292 | * will be re-checked with proper locks held further down the line. | |
1293 | */ | |
ac66f547 PZ |
1294 | if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu)) |
1295 | goto out; | |
1296 | ||
0c98d344 | 1297 | if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed)) |
ac66f547 PZ |
1298 | goto out; |
1299 | ||
0c98d344 | 1300 | if (!cpumask_test_cpu(arg.src_cpu, &arg.dst_task->cpus_allowed)) |
ac66f547 PZ |
1301 | goto out; |
1302 | ||
286549dc | 1303 | trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); |
ac66f547 PZ |
1304 | ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); |
1305 | ||
1306 | out: | |
ac66f547 PZ |
1307 | return ret; |
1308 | } | |
1309 | ||
1da177e4 LT |
1310 | /* |
1311 | * wait_task_inactive - wait for a thread to unschedule. | |
1312 | * | |
85ba2d86 RM |
1313 | * If @match_state is nonzero, it's the @p->state value just checked and |
1314 | * not expected to change. If it changes, i.e. @p might have woken up, | |
1315 | * then return zero. When we succeed in waiting for @p to be off its CPU, | |
1316 | * we return a positive number (its total switch count). If a second call | |
1317 | * a short while later returns the same number, the caller can be sure that | |
1318 | * @p has remained unscheduled the whole time. | |
1319 | * | |
1da177e4 LT |
1320 | * The caller must ensure that the task *will* unschedule sometime soon, |
1321 | * else this function might spin for a *long* time. This function can't | |
1322 | * be called with interrupts off, or it may introduce deadlock with | |
1323 | * smp_call_function() if an IPI is sent by the same process we are | |
1324 | * waiting to become inactive. | |
1325 | */ | |
85ba2d86 | 1326 | unsigned long wait_task_inactive(struct task_struct *p, long match_state) |
1da177e4 | 1327 | { |
da0c1e65 | 1328 | int running, queued; |
eb580751 | 1329 | struct rq_flags rf; |
85ba2d86 | 1330 | unsigned long ncsw; |
70b97a7f | 1331 | struct rq *rq; |
1da177e4 | 1332 | |
3a5c359a AK |
1333 | for (;;) { |
1334 | /* | |
1335 | * We do the initial early heuristics without holding | |
1336 | * any task-queue locks at all. We'll only try to get | |
1337 | * the runqueue lock when things look like they will | |
1338 | * work out! | |
1339 | */ | |
1340 | rq = task_rq(p); | |
fa490cfd | 1341 | |
3a5c359a AK |
1342 | /* |
1343 | * If the task is actively running on another CPU | |
1344 | * still, just relax and busy-wait without holding | |
1345 | * any locks. | |
1346 | * | |
1347 | * NOTE! Since we don't hold any locks, it's not | |
1348 | * even sure that "rq" stays as the right runqueue! | |
1349 | * But we don't care, since "task_running()" will | |
1350 | * return false if the runqueue has changed and p | |
1351 | * is actually now running somewhere else! | |
1352 | */ | |
85ba2d86 RM |
1353 | while (task_running(rq, p)) { |
1354 | if (match_state && unlikely(p->state != match_state)) | |
1355 | return 0; | |
3a5c359a | 1356 | cpu_relax(); |
85ba2d86 | 1357 | } |
fa490cfd | 1358 | |
3a5c359a AK |
1359 | /* |
1360 | * Ok, time to look more closely! We need the rq | |
1361 | * lock now, to be *sure*. If we're wrong, we'll | |
1362 | * just go back and repeat. | |
1363 | */ | |
eb580751 | 1364 | rq = task_rq_lock(p, &rf); |
27a9da65 | 1365 | trace_sched_wait_task(p); |
3a5c359a | 1366 | running = task_running(rq, p); |
da0c1e65 | 1367 | queued = task_on_rq_queued(p); |
85ba2d86 | 1368 | ncsw = 0; |
f31e11d8 | 1369 | if (!match_state || p->state == match_state) |
93dcf55f | 1370 | ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ |
eb580751 | 1371 | task_rq_unlock(rq, p, &rf); |
fa490cfd | 1372 | |
85ba2d86 RM |
1373 | /* |
1374 | * If it changed from the expected state, bail out now. | |
1375 | */ | |
1376 | if (unlikely(!ncsw)) | |
1377 | break; | |
1378 | ||
3a5c359a AK |
1379 | /* |
1380 | * Was it really running after all now that we | |
1381 | * checked with the proper locks actually held? | |
1382 | * | |
1383 | * Oops. Go back and try again.. | |
1384 | */ | |
1385 | if (unlikely(running)) { | |
1386 | cpu_relax(); | |
1387 | continue; | |
1388 | } | |
fa490cfd | 1389 | |
3a5c359a AK |
1390 | /* |
1391 | * It's not enough that it's not actively running, | |
1392 | * it must be off the runqueue _entirely_, and not | |
1393 | * preempted! | |
1394 | * | |
80dd99b3 | 1395 | * So if it was still runnable (but just not actively |
3a5c359a AK |
1396 | * running right now), it's preempted, and we should |
1397 | * yield - it could be a while. | |
1398 | */ | |
da0c1e65 | 1399 | if (unlikely(queued)) { |
8b0e1953 | 1400 | ktime_t to = NSEC_PER_SEC / HZ; |
8eb90c30 TG |
1401 | |
1402 | set_current_state(TASK_UNINTERRUPTIBLE); | |
1403 | schedule_hrtimeout(&to, HRTIMER_MODE_REL); | |
3a5c359a AK |
1404 | continue; |
1405 | } | |
fa490cfd | 1406 | |
3a5c359a AK |
1407 | /* |
1408 | * Ahh, all good. It wasn't running, and it wasn't | |
1409 | * runnable, which means that it will never become | |
1410 | * running in the future either. We're all done! | |
1411 | */ | |
1412 | break; | |
1413 | } | |
85ba2d86 RM |
1414 | |
1415 | return ncsw; | |
1da177e4 LT |
1416 | } |
1417 | ||
1418 | /*** | |
1419 | * kick_process - kick a running thread to enter/exit the kernel | |
1420 | * @p: the to-be-kicked thread | |
1421 | * | |
1422 | * Cause a process which is running on another CPU to enter | |
1423 | * kernel-mode, without any delay. (to get signals handled.) | |
1424 | * | |
25985edc | 1425 | * NOTE: this function doesn't have to take the runqueue lock, |
1da177e4 LT |
1426 | * because all it wants to ensure is that the remote task enters |
1427 | * the kernel. If the IPI races and the task has been migrated | |
1428 | * to another CPU then no harm is done and the purpose has been | |
1429 | * achieved as well. | |
1430 | */ | |
36c8b586 | 1431 | void kick_process(struct task_struct *p) |
1da177e4 LT |
1432 | { |
1433 | int cpu; | |
1434 | ||
1435 | preempt_disable(); | |
1436 | cpu = task_cpu(p); | |
1437 | if ((cpu != smp_processor_id()) && task_curr(p)) | |
1438 | smp_send_reschedule(cpu); | |
1439 | preempt_enable(); | |
1440 | } | |
b43e3521 | 1441 | EXPORT_SYMBOL_GPL(kick_process); |
1da177e4 | 1442 | |
30da688e | 1443 | /* |
013fdb80 | 1444 | * ->cpus_allowed is protected by both rq->lock and p->pi_lock |
e9d867a6 PZI |
1445 | * |
1446 | * A few notes on cpu_active vs cpu_online: | |
1447 | * | |
1448 | * - cpu_active must be a subset of cpu_online | |
1449 | * | |
1450 | * - on cpu-up we allow per-cpu kthreads on the online && !active cpu, | |
1451 | * see __set_cpus_allowed_ptr(). At this point the newly online | |
d1ccc66d | 1452 | * CPU isn't yet part of the sched domains, and balancing will not |
e9d867a6 PZI |
1453 | * see it. |
1454 | * | |
d1ccc66d | 1455 | * - on CPU-down we clear cpu_active() to mask the sched domains and |
e9d867a6 | 1456 | * avoid the load balancer to place new tasks on the to be removed |
d1ccc66d | 1457 | * CPU. Existing tasks will remain running there and will be taken |
e9d867a6 PZI |
1458 | * off. |
1459 | * | |
1460 | * This means that fallback selection must not select !active CPUs. | |
1461 | * And can assume that any active CPU must be online. Conversely | |
1462 | * select_task_rq() below may allow selection of !active CPUs in order | |
1463 | * to satisfy the above rules. | |
30da688e | 1464 | */ |
5da9a0fb PZ |
1465 | static int select_fallback_rq(int cpu, struct task_struct *p) |
1466 | { | |
aa00d89c TC |
1467 | int nid = cpu_to_node(cpu); |
1468 | const struct cpumask *nodemask = NULL; | |
2baab4e9 PZ |
1469 | enum { cpuset, possible, fail } state = cpuset; |
1470 | int dest_cpu; | |
5da9a0fb | 1471 | |
aa00d89c | 1472 | /* |
d1ccc66d IM |
1473 | * If the node that the CPU is on has been offlined, cpu_to_node() |
1474 | * will return -1. There is no CPU on the node, and we should | |
1475 | * select the CPU on the other node. | |
aa00d89c TC |
1476 | */ |
1477 | if (nid != -1) { | |
1478 | nodemask = cpumask_of_node(nid); | |
1479 | ||
1480 | /* Look for allowed, online CPU in same node. */ | |
1481 | for_each_cpu(dest_cpu, nodemask) { | |
aa00d89c TC |
1482 | if (!cpu_active(dest_cpu)) |
1483 | continue; | |
0c98d344 | 1484 | if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed)) |
aa00d89c TC |
1485 | return dest_cpu; |
1486 | } | |
2baab4e9 | 1487 | } |
5da9a0fb | 1488 | |
2baab4e9 PZ |
1489 | for (;;) { |
1490 | /* Any allowed, online CPU? */ | |
0c98d344 | 1491 | for_each_cpu(dest_cpu, &p->cpus_allowed) { |
feb245e3 TH |
1492 | if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) |
1493 | continue; | |
1494 | if (!cpu_online(dest_cpu)) | |
2baab4e9 PZ |
1495 | continue; |
1496 | goto out; | |
1497 | } | |
5da9a0fb | 1498 | |
e73e85f0 | 1499 | /* No more Mr. Nice Guy. */ |
2baab4e9 PZ |
1500 | switch (state) { |
1501 | case cpuset: | |
e73e85f0 ON |
1502 | if (IS_ENABLED(CONFIG_CPUSETS)) { |
1503 | cpuset_cpus_allowed_fallback(p); | |
1504 | state = possible; | |
1505 | break; | |
1506 | } | |
d1ccc66d | 1507 | /* Fall-through */ |
2baab4e9 PZ |
1508 | case possible: |
1509 | do_set_cpus_allowed(p, cpu_possible_mask); | |
1510 | state = fail; | |
1511 | break; | |
1512 | ||
1513 | case fail: | |
1514 | BUG(); | |
1515 | break; | |
1516 | } | |
1517 | } | |
1518 | ||
1519 | out: | |
1520 | if (state != cpuset) { | |
1521 | /* | |
1522 | * Don't tell them about moving exiting tasks or | |
1523 | * kernel threads (both mm NULL), since they never | |
1524 | * leave kernel. | |
1525 | */ | |
1526 | if (p->mm && printk_ratelimit()) { | |
aac74dc4 | 1527 | printk_deferred("process %d (%s) no longer affine to cpu%d\n", |
2baab4e9 PZ |
1528 | task_pid_nr(p), p->comm, cpu); |
1529 | } | |
5da9a0fb PZ |
1530 | } |
1531 | ||
1532 | return dest_cpu; | |
1533 | } | |
1534 | ||
e2912009 | 1535 | /* |
013fdb80 | 1536 | * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. |
e2912009 | 1537 | */ |
970b13ba | 1538 | static inline |
ac66f547 | 1539 | int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) |
970b13ba | 1540 | { |
cbce1a68 PZ |
1541 | lockdep_assert_held(&p->pi_lock); |
1542 | ||
4b53a341 | 1543 | if (p->nr_cpus_allowed > 1) |
6c1d9410 | 1544 | cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags); |
e9d867a6 | 1545 | else |
0c98d344 | 1546 | cpu = cpumask_any(&p->cpus_allowed); |
e2912009 PZ |
1547 | |
1548 | /* | |
1549 | * In order not to call set_task_cpu() on a blocking task we need | |
1550 | * to rely on ttwu() to place the task on a valid ->cpus_allowed | |
d1ccc66d | 1551 | * CPU. |
e2912009 PZ |
1552 | * |
1553 | * Since this is common to all placement strategies, this lives here. | |
1554 | * | |
1555 | * [ this allows ->select_task() to simply return task_cpu(p) and | |
1556 | * not worry about this generic constraint ] | |
1557 | */ | |
0c98d344 | 1558 | if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) || |
70f11205 | 1559 | !cpu_online(cpu))) |
5da9a0fb | 1560 | cpu = select_fallback_rq(task_cpu(p), p); |
e2912009 PZ |
1561 | |
1562 | return cpu; | |
970b13ba | 1563 | } |
09a40af5 MG |
1564 | |
1565 | static void update_avg(u64 *avg, u64 sample) | |
1566 | { | |
1567 | s64 diff = sample - *avg; | |
1568 | *avg += diff >> 3; | |
1569 | } | |
25834c73 | 1570 | |
f5832c19 NP |
1571 | void sched_set_stop_task(int cpu, struct task_struct *stop) |
1572 | { | |
1573 | struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; | |
1574 | struct task_struct *old_stop = cpu_rq(cpu)->stop; | |
1575 | ||
1576 | if (stop) { | |
1577 | /* | |
1578 | * Make it appear like a SCHED_FIFO task, its something | |
1579 | * userspace knows about and won't get confused about. | |
1580 | * | |
1581 | * Also, it will make PI more or less work without too | |
1582 | * much confusion -- but then, stop work should not | |
1583 | * rely on PI working anyway. | |
1584 | */ | |
1585 | sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); | |
1586 | ||
1587 | stop->sched_class = &stop_sched_class; | |
1588 | } | |
1589 | ||
1590 | cpu_rq(cpu)->stop = stop; | |
1591 | ||
1592 | if (old_stop) { | |
1593 | /* | |
1594 | * Reset it back to a normal scheduling class so that | |
1595 | * it can die in pieces. | |
1596 | */ | |
1597 | old_stop->sched_class = &rt_sched_class; | |
1598 | } | |
1599 | } | |
1600 | ||
25834c73 PZ |
1601 | #else |
1602 | ||
1603 | static inline int __set_cpus_allowed_ptr(struct task_struct *p, | |
1604 | const struct cpumask *new_mask, bool check) | |
1605 | { | |
1606 | return set_cpus_allowed_ptr(p, new_mask); | |
1607 | } | |
1608 | ||
5cc389bc | 1609 | #endif /* CONFIG_SMP */ |
970b13ba | 1610 | |
d7c01d27 | 1611 | static void |
b84cb5df | 1612 | ttwu_stat(struct task_struct *p, int cpu, int wake_flags) |
9ed3811a | 1613 | { |
4fa8d299 | 1614 | struct rq *rq; |
b84cb5df | 1615 | |
4fa8d299 JP |
1616 | if (!schedstat_enabled()) |
1617 | return; | |
1618 | ||
1619 | rq = this_rq(); | |
d7c01d27 | 1620 | |
4fa8d299 JP |
1621 | #ifdef CONFIG_SMP |
1622 | if (cpu == rq->cpu) { | |
ae92882e JP |
1623 | schedstat_inc(rq->ttwu_local); |
1624 | schedstat_inc(p->se.statistics.nr_wakeups_local); | |
d7c01d27 PZ |
1625 | } else { |
1626 | struct sched_domain *sd; | |
1627 | ||
ae92882e | 1628 | schedstat_inc(p->se.statistics.nr_wakeups_remote); |
057f3fad | 1629 | rcu_read_lock(); |
4fa8d299 | 1630 | for_each_domain(rq->cpu, sd) { |
d7c01d27 | 1631 | if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { |
ae92882e | 1632 | schedstat_inc(sd->ttwu_wake_remote); |
d7c01d27 PZ |
1633 | break; |
1634 | } | |
1635 | } | |
057f3fad | 1636 | rcu_read_unlock(); |
d7c01d27 | 1637 | } |
f339b9dc PZ |
1638 | |
1639 | if (wake_flags & WF_MIGRATED) | |
ae92882e | 1640 | schedstat_inc(p->se.statistics.nr_wakeups_migrate); |
d7c01d27 PZ |
1641 | #endif /* CONFIG_SMP */ |
1642 | ||
ae92882e JP |
1643 | schedstat_inc(rq->ttwu_count); |
1644 | schedstat_inc(p->se.statistics.nr_wakeups); | |
d7c01d27 PZ |
1645 | |
1646 | if (wake_flags & WF_SYNC) | |
ae92882e | 1647 | schedstat_inc(p->se.statistics.nr_wakeups_sync); |
d7c01d27 PZ |
1648 | } |
1649 | ||
1de64443 | 1650 | static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) |
d7c01d27 | 1651 | { |
9ed3811a | 1652 | activate_task(rq, p, en_flags); |
da0c1e65 | 1653 | p->on_rq = TASK_ON_RQ_QUEUED; |
c2f7115e | 1654 | |
d1ccc66d | 1655 | /* If a worker is waking up, notify the workqueue: */ |
c2f7115e PZ |
1656 | if (p->flags & PF_WQ_WORKER) |
1657 | wq_worker_waking_up(p, cpu_of(rq)); | |
9ed3811a TH |
1658 | } |
1659 | ||
23f41eeb PZ |
1660 | /* |
1661 | * Mark the task runnable and perform wakeup-preemption. | |
1662 | */ | |
e7904a28 | 1663 | static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags, |
d8ac8971 | 1664 | struct rq_flags *rf) |
9ed3811a | 1665 | { |
9ed3811a | 1666 | check_preempt_curr(rq, p, wake_flags); |
9ed3811a | 1667 | p->state = TASK_RUNNING; |
fbd705a0 PZ |
1668 | trace_sched_wakeup(p); |
1669 | ||
9ed3811a | 1670 | #ifdef CONFIG_SMP |
4c9a4bc8 PZ |
1671 | if (p->sched_class->task_woken) { |
1672 | /* | |
cbce1a68 PZ |
1673 | * Our task @p is fully woken up and running; so its safe to |
1674 | * drop the rq->lock, hereafter rq is only used for statistics. | |
4c9a4bc8 | 1675 | */ |
d8ac8971 | 1676 | rq_unpin_lock(rq, rf); |
9ed3811a | 1677 | p->sched_class->task_woken(rq, p); |
d8ac8971 | 1678 | rq_repin_lock(rq, rf); |
4c9a4bc8 | 1679 | } |
9ed3811a | 1680 | |
e69c6341 | 1681 | if (rq->idle_stamp) { |
78becc27 | 1682 | u64 delta = rq_clock(rq) - rq->idle_stamp; |
9bd721c5 | 1683 | u64 max = 2*rq->max_idle_balance_cost; |
9ed3811a | 1684 | |
abfafa54 JL |
1685 | update_avg(&rq->avg_idle, delta); |
1686 | ||
1687 | if (rq->avg_idle > max) | |
9ed3811a | 1688 | rq->avg_idle = max; |
abfafa54 | 1689 | |
9ed3811a TH |
1690 | rq->idle_stamp = 0; |
1691 | } | |
1692 | #endif | |
1693 | } | |
1694 | ||
c05fbafb | 1695 | static void |
e7904a28 | 1696 | ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, |
d8ac8971 | 1697 | struct rq_flags *rf) |
c05fbafb | 1698 | { |
77558e4d | 1699 | int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK; |
b5179ac7 | 1700 | |
cbce1a68 PZ |
1701 | lockdep_assert_held(&rq->lock); |
1702 | ||
c05fbafb PZ |
1703 | #ifdef CONFIG_SMP |
1704 | if (p->sched_contributes_to_load) | |
1705 | rq->nr_uninterruptible--; | |
b5179ac7 | 1706 | |
b5179ac7 | 1707 | if (wake_flags & WF_MIGRATED) |
59efa0ba | 1708 | en_flags |= ENQUEUE_MIGRATED; |
c05fbafb PZ |
1709 | #endif |
1710 | ||
b5179ac7 | 1711 | ttwu_activate(rq, p, en_flags); |
d8ac8971 | 1712 | ttwu_do_wakeup(rq, p, wake_flags, rf); |
c05fbafb PZ |
1713 | } |
1714 | ||
1715 | /* | |
1716 | * Called in case the task @p isn't fully descheduled from its runqueue, | |
1717 | * in this case we must do a remote wakeup. Its a 'light' wakeup though, | |
1718 | * since all we need to do is flip p->state to TASK_RUNNING, since | |
1719 | * the task is still ->on_rq. | |
1720 | */ | |
1721 | static int ttwu_remote(struct task_struct *p, int wake_flags) | |
1722 | { | |
eb580751 | 1723 | struct rq_flags rf; |
c05fbafb PZ |
1724 | struct rq *rq; |
1725 | int ret = 0; | |
1726 | ||
eb580751 | 1727 | rq = __task_rq_lock(p, &rf); |
da0c1e65 | 1728 | if (task_on_rq_queued(p)) { |
1ad4ec0d FW |
1729 | /* check_preempt_curr() may use rq clock */ |
1730 | update_rq_clock(rq); | |
d8ac8971 | 1731 | ttwu_do_wakeup(rq, p, wake_flags, &rf); |
c05fbafb PZ |
1732 | ret = 1; |
1733 | } | |
eb580751 | 1734 | __task_rq_unlock(rq, &rf); |
c05fbafb PZ |
1735 | |
1736 | return ret; | |
1737 | } | |
1738 | ||
317f3941 | 1739 | #ifdef CONFIG_SMP |
e3baac47 | 1740 | void sched_ttwu_pending(void) |
317f3941 PZ |
1741 | { |
1742 | struct rq *rq = this_rq(); | |
fa14ff4a | 1743 | struct llist_node *llist = llist_del_all(&rq->wake_list); |
73215849 | 1744 | struct task_struct *p, *t; |
d8ac8971 | 1745 | struct rq_flags rf; |
317f3941 | 1746 | |
e3baac47 PZ |
1747 | if (!llist) |
1748 | return; | |
1749 | ||
8a8c69c3 | 1750 | rq_lock_irqsave(rq, &rf); |
77558e4d | 1751 | update_rq_clock(rq); |
317f3941 | 1752 | |
73215849 BP |
1753 | llist_for_each_entry_safe(p, t, llist, wake_entry) |
1754 | ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); | |
317f3941 | 1755 | |
8a8c69c3 | 1756 | rq_unlock_irqrestore(rq, &rf); |
317f3941 PZ |
1757 | } |
1758 | ||
1759 | void scheduler_ipi(void) | |
1760 | { | |
f27dde8d PZ |
1761 | /* |
1762 | * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting | |
1763 | * TIF_NEED_RESCHED remotely (for the first time) will also send | |
1764 | * this IPI. | |
1765 | */ | |
8cb75e0c | 1766 | preempt_fold_need_resched(); |
f27dde8d | 1767 | |
fd2ac4f4 | 1768 | if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) |
c5d753a5 PZ |
1769 | return; |
1770 | ||
1771 | /* | |
1772 | * Not all reschedule IPI handlers call irq_enter/irq_exit, since | |
1773 | * traditionally all their work was done from the interrupt return | |
1774 | * path. Now that we actually do some work, we need to make sure | |
1775 | * we do call them. | |
1776 | * | |
1777 | * Some archs already do call them, luckily irq_enter/exit nest | |
1778 | * properly. | |
1779 | * | |
1780 | * Arguably we should visit all archs and update all handlers, | |
1781 | * however a fair share of IPIs are still resched only so this would | |
1782 | * somewhat pessimize the simple resched case. | |
1783 | */ | |
1784 | irq_enter(); | |
fa14ff4a | 1785 | sched_ttwu_pending(); |
ca38062e SS |
1786 | |
1787 | /* | |
1788 | * Check if someone kicked us for doing the nohz idle load balance. | |
1789 | */ | |
873b4c65 | 1790 | if (unlikely(got_nohz_idle_kick())) { |
6eb57e0d | 1791 | this_rq()->idle_balance = 1; |
ca38062e | 1792 | raise_softirq_irqoff(SCHED_SOFTIRQ); |
6eb57e0d | 1793 | } |
c5d753a5 | 1794 | irq_exit(); |
317f3941 PZ |
1795 | } |
1796 | ||
b7e7ade3 | 1797 | static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags) |
317f3941 | 1798 | { |
e3baac47 PZ |
1799 | struct rq *rq = cpu_rq(cpu); |
1800 | ||
b7e7ade3 PZ |
1801 | p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED); |
1802 | ||
e3baac47 PZ |
1803 | if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) { |
1804 | if (!set_nr_if_polling(rq->idle)) | |
1805 | smp_send_reschedule(cpu); | |
1806 | else | |
1807 | trace_sched_wake_idle_without_ipi(cpu); | |
1808 | } | |
317f3941 | 1809 | } |
d6aa8f85 | 1810 | |
f6be8af1 CL |
1811 | void wake_up_if_idle(int cpu) |
1812 | { | |
1813 | struct rq *rq = cpu_rq(cpu); | |
8a8c69c3 | 1814 | struct rq_flags rf; |
f6be8af1 | 1815 | |
fd7de1e8 AL |
1816 | rcu_read_lock(); |
1817 | ||
1818 | if (!is_idle_task(rcu_dereference(rq->curr))) | |
1819 | goto out; | |
f6be8af1 CL |
1820 | |
1821 | if (set_nr_if_polling(rq->idle)) { | |
1822 | trace_sched_wake_idle_without_ipi(cpu); | |
1823 | } else { | |
8a8c69c3 | 1824 | rq_lock_irqsave(rq, &rf); |
f6be8af1 CL |
1825 | if (is_idle_task(rq->curr)) |
1826 | smp_send_reschedule(cpu); | |
d1ccc66d | 1827 | /* Else CPU is not idle, do nothing here: */ |
8a8c69c3 | 1828 | rq_unlock_irqrestore(rq, &rf); |
f6be8af1 | 1829 | } |
fd7de1e8 AL |
1830 | |
1831 | out: | |
1832 | rcu_read_unlock(); | |
f6be8af1 CL |
1833 | } |
1834 | ||
39be3501 | 1835 | bool cpus_share_cache(int this_cpu, int that_cpu) |
518cd623 PZ |
1836 | { |
1837 | return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); | |
1838 | } | |
d6aa8f85 | 1839 | #endif /* CONFIG_SMP */ |
317f3941 | 1840 | |
b5179ac7 | 1841 | static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) |
c05fbafb PZ |
1842 | { |
1843 | struct rq *rq = cpu_rq(cpu); | |
d8ac8971 | 1844 | struct rq_flags rf; |
c05fbafb | 1845 | |
17d9f311 | 1846 | #if defined(CONFIG_SMP) |
39be3501 | 1847 | if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { |
d1ccc66d | 1848 | sched_clock_cpu(cpu); /* Sync clocks across CPUs */ |
b7e7ade3 | 1849 | ttwu_queue_remote(p, cpu, wake_flags); |
317f3941 PZ |
1850 | return; |
1851 | } | |
1852 | #endif | |
1853 | ||
8a8c69c3 | 1854 | rq_lock(rq, &rf); |
77558e4d | 1855 | update_rq_clock(rq); |
d8ac8971 | 1856 | ttwu_do_activate(rq, p, wake_flags, &rf); |
8a8c69c3 | 1857 | rq_unlock(rq, &rf); |
9ed3811a TH |
1858 | } |
1859 | ||
8643cda5 PZ |
1860 | /* |
1861 | * Notes on Program-Order guarantees on SMP systems. | |
1862 | * | |
1863 | * MIGRATION | |
1864 | * | |
1865 | * The basic program-order guarantee on SMP systems is that when a task [t] | |
d1ccc66d IM |
1866 | * migrates, all its activity on its old CPU [c0] happens-before any subsequent |
1867 | * execution on its new CPU [c1]. | |
8643cda5 PZ |
1868 | * |
1869 | * For migration (of runnable tasks) this is provided by the following means: | |
1870 | * | |
1871 | * A) UNLOCK of the rq(c0)->lock scheduling out task t | |
1872 | * B) migration for t is required to synchronize *both* rq(c0)->lock and | |
1873 | * rq(c1)->lock (if not at the same time, then in that order). | |
1874 | * C) LOCK of the rq(c1)->lock scheduling in task | |
1875 | * | |
1876 | * Transitivity guarantees that B happens after A and C after B. | |
1877 | * Note: we only require RCpc transitivity. | |
d1ccc66d | 1878 | * Note: the CPU doing B need not be c0 or c1 |
8643cda5 PZ |
1879 | * |
1880 | * Example: | |
1881 | * | |
1882 | * CPU0 CPU1 CPU2 | |
1883 | * | |
1884 | * LOCK rq(0)->lock | |
1885 | * sched-out X | |
1886 | * sched-in Y | |
1887 | * UNLOCK rq(0)->lock | |
1888 | * | |
1889 | * LOCK rq(0)->lock // orders against CPU0 | |
1890 | * dequeue X | |
1891 | * UNLOCK rq(0)->lock | |
1892 | * | |
1893 | * LOCK rq(1)->lock | |
1894 | * enqueue X | |
1895 | * UNLOCK rq(1)->lock | |
1896 | * | |
1897 | * LOCK rq(1)->lock // orders against CPU2 | |
1898 | * sched-out Z | |
1899 | * sched-in X | |
1900 | * UNLOCK rq(1)->lock | |
1901 | * | |
1902 | * | |
1903 | * BLOCKING -- aka. SLEEP + WAKEUP | |
1904 | * | |
1905 | * For blocking we (obviously) need to provide the same guarantee as for | |
1906 | * migration. However the means are completely different as there is no lock | |
1907 | * chain to provide order. Instead we do: | |
1908 | * | |
1909 | * 1) smp_store_release(X->on_cpu, 0) | |
1f03e8d2 | 1910 | * 2) smp_cond_load_acquire(!X->on_cpu) |
8643cda5 PZ |
1911 | * |
1912 | * Example: | |
1913 | * | |
1914 | * CPU0 (schedule) CPU1 (try_to_wake_up) CPU2 (schedule) | |
1915 | * | |
1916 | * LOCK rq(0)->lock LOCK X->pi_lock | |
1917 | * dequeue X | |
1918 | * sched-out X | |
1919 | * smp_store_release(X->on_cpu, 0); | |
1920 | * | |
1f03e8d2 | 1921 | * smp_cond_load_acquire(&X->on_cpu, !VAL); |
8643cda5 PZ |
1922 | * X->state = WAKING |
1923 | * set_task_cpu(X,2) | |
1924 | * | |
1925 | * LOCK rq(2)->lock | |
1926 | * enqueue X | |
1927 | * X->state = RUNNING | |
1928 | * UNLOCK rq(2)->lock | |
1929 | * | |
1930 | * LOCK rq(2)->lock // orders against CPU1 | |
1931 | * sched-out Z | |
1932 | * sched-in X | |
1933 | * UNLOCK rq(2)->lock | |
1934 | * | |
1935 | * UNLOCK X->pi_lock | |
1936 | * UNLOCK rq(0)->lock | |
1937 | * | |
1938 | * | |
1939 | * However; for wakeups there is a second guarantee we must provide, namely we | |
1940 | * must observe the state that lead to our wakeup. That is, not only must our | |
1941 | * task observe its own prior state, it must also observe the stores prior to | |
1942 | * its wakeup. | |
1943 | * | |
1944 | * This means that any means of doing remote wakeups must order the CPU doing | |
1945 | * the wakeup against the CPU the task is going to end up running on. This, | |
1946 | * however, is already required for the regular Program-Order guarantee above, | |
1f03e8d2 | 1947 | * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). |
8643cda5 PZ |
1948 | * |
1949 | */ | |
1950 | ||
9ed3811a | 1951 | /** |
1da177e4 | 1952 | * try_to_wake_up - wake up a thread |
9ed3811a | 1953 | * @p: the thread to be awakened |
1da177e4 | 1954 | * @state: the mask of task states that can be woken |
9ed3811a | 1955 | * @wake_flags: wake modifier flags (WF_*) |
1da177e4 | 1956 | * |
a2250238 | 1957 | * If (@state & @p->state) @p->state = TASK_RUNNING. |
1da177e4 | 1958 | * |
a2250238 PZ |
1959 | * If the task was not queued/runnable, also place it back on a runqueue. |
1960 | * | |
1961 | * Atomic against schedule() which would dequeue a task, also see | |
1962 | * set_current_state(). | |
1963 | * | |
1964 | * Return: %true if @p->state changes (an actual wakeup was done), | |
1965 | * %false otherwise. | |
1da177e4 | 1966 | */ |
e4a52bcb PZ |
1967 | static int |
1968 | try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) | |
1da177e4 | 1969 | { |
1da177e4 | 1970 | unsigned long flags; |
c05fbafb | 1971 | int cpu, success = 0; |
2398f2c6 | 1972 | |
e0acd0a6 ON |
1973 | /* |
1974 | * If we are going to wake up a thread waiting for CONDITION we | |
1975 | * need to ensure that CONDITION=1 done by the caller can not be | |
1976 | * reordered with p->state check below. This pairs with mb() in | |
1977 | * set_current_state() the waiting thread does. | |
1978 | */ | |
013fdb80 | 1979 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
d89e588c | 1980 | smp_mb__after_spinlock(); |
e9c84311 | 1981 | if (!(p->state & state)) |
1da177e4 LT |
1982 | goto out; |
1983 | ||
fbd705a0 PZ |
1984 | trace_sched_waking(p); |
1985 | ||
d1ccc66d IM |
1986 | /* We're going to change ->state: */ |
1987 | success = 1; | |
1da177e4 | 1988 | cpu = task_cpu(p); |
1da177e4 | 1989 | |
135e8c92 BS |
1990 | /* |
1991 | * Ensure we load p->on_rq _after_ p->state, otherwise it would | |
1992 | * be possible to, falsely, observe p->on_rq == 0 and get stuck | |
1993 | * in smp_cond_load_acquire() below. | |
1994 | * | |
1995 | * sched_ttwu_pending() try_to_wake_up() | |
1996 | * [S] p->on_rq = 1; [L] P->state | |
1997 | * UNLOCK rq->lock -----. | |
1998 | * \ | |
1999 | * +--- RMB | |
2000 | * schedule() / | |
2001 | * LOCK rq->lock -----' | |
2002 | * UNLOCK rq->lock | |
2003 | * | |
2004 | * [task p] | |
2005 | * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq | |
2006 | * | |
2007 | * Pairs with the UNLOCK+LOCK on rq->lock from the | |
2008 | * last wakeup of our task and the schedule that got our task | |
2009 | * current. | |
2010 | */ | |
2011 | smp_rmb(); | |
c05fbafb PZ |
2012 | if (p->on_rq && ttwu_remote(p, wake_flags)) |
2013 | goto stat; | |
1da177e4 | 2014 | |
1da177e4 | 2015 | #ifdef CONFIG_SMP |
ecf7d01c PZ |
2016 | /* |
2017 | * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be | |
2018 | * possible to, falsely, observe p->on_cpu == 0. | |
2019 | * | |
2020 | * One must be running (->on_cpu == 1) in order to remove oneself | |
2021 | * from the runqueue. | |
2022 | * | |
2023 | * [S] ->on_cpu = 1; [L] ->on_rq | |
2024 | * UNLOCK rq->lock | |
2025 | * RMB | |
2026 | * LOCK rq->lock | |
2027 | * [S] ->on_rq = 0; [L] ->on_cpu | |
2028 | * | |
2029 | * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock | |
2030 | * from the consecutive calls to schedule(); the first switching to our | |
2031 | * task, the second putting it to sleep. | |
2032 | */ | |
2033 | smp_rmb(); | |
2034 | ||
e9c84311 | 2035 | /* |
d1ccc66d | 2036 | * If the owning (remote) CPU is still in the middle of schedule() with |
c05fbafb | 2037 | * this task as prev, wait until its done referencing the task. |
b75a2253 PZ |
2038 | * |
2039 | * Pairs with the smp_store_release() in finish_lock_switch(). | |
2040 | * | |
2041 | * This ensures that tasks getting woken will be fully ordered against | |
2042 | * their previous state and preserve Program Order. | |
0970d299 | 2043 | */ |
1f03e8d2 | 2044 | smp_cond_load_acquire(&p->on_cpu, !VAL); |
1da177e4 | 2045 | |
a8e4f2ea | 2046 | p->sched_contributes_to_load = !!task_contributes_to_load(p); |
e9c84311 | 2047 | p->state = TASK_WAKING; |
e7693a36 | 2048 | |
e33a9bba TH |
2049 | if (p->in_iowait) { |
2050 | delayacct_blkio_end(); | |
2051 | atomic_dec(&task_rq(p)->nr_iowait); | |
2052 | } | |
2053 | ||
ac66f547 | 2054 | cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); |
f339b9dc PZ |
2055 | if (task_cpu(p) != cpu) { |
2056 | wake_flags |= WF_MIGRATED; | |
e4a52bcb | 2057 | set_task_cpu(p, cpu); |
f339b9dc | 2058 | } |
e33a9bba TH |
2059 | |
2060 | #else /* CONFIG_SMP */ | |
2061 | ||
2062 | if (p->in_iowait) { | |
2063 | delayacct_blkio_end(); | |
2064 | atomic_dec(&task_rq(p)->nr_iowait); | |
2065 | } | |
2066 | ||
1da177e4 | 2067 | #endif /* CONFIG_SMP */ |
1da177e4 | 2068 | |
b5179ac7 | 2069 | ttwu_queue(p, cpu, wake_flags); |
c05fbafb | 2070 | stat: |
4fa8d299 | 2071 | ttwu_stat(p, cpu, wake_flags); |
1da177e4 | 2072 | out: |
013fdb80 | 2073 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 LT |
2074 | |
2075 | return success; | |
2076 | } | |
2077 | ||
21aa9af0 TH |
2078 | /** |
2079 | * try_to_wake_up_local - try to wake up a local task with rq lock held | |
2080 | * @p: the thread to be awakened | |
bf50f0e8 | 2081 | * @rf: request-queue flags for pinning |
21aa9af0 | 2082 | * |
2acca55e | 2083 | * Put @p on the run-queue if it's not already there. The caller must |
21aa9af0 | 2084 | * ensure that this_rq() is locked, @p is bound to this_rq() and not |
2acca55e | 2085 | * the current task. |
21aa9af0 | 2086 | */ |
d8ac8971 | 2087 | static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf) |
21aa9af0 TH |
2088 | { |
2089 | struct rq *rq = task_rq(p); | |
21aa9af0 | 2090 | |
383efcd0 TH |
2091 | if (WARN_ON_ONCE(rq != this_rq()) || |
2092 | WARN_ON_ONCE(p == current)) | |
2093 | return; | |
2094 | ||
21aa9af0 TH |
2095 | lockdep_assert_held(&rq->lock); |
2096 | ||
2acca55e | 2097 | if (!raw_spin_trylock(&p->pi_lock)) { |
cbce1a68 PZ |
2098 | /* |
2099 | * This is OK, because current is on_cpu, which avoids it being | |
2100 | * picked for load-balance and preemption/IRQs are still | |
2101 | * disabled avoiding further scheduler activity on it and we've | |
2102 | * not yet picked a replacement task. | |
2103 | */ | |
8a8c69c3 | 2104 | rq_unlock(rq, rf); |
2acca55e | 2105 | raw_spin_lock(&p->pi_lock); |
8a8c69c3 | 2106 | rq_relock(rq, rf); |
2acca55e PZ |
2107 | } |
2108 | ||
21aa9af0 | 2109 | if (!(p->state & TASK_NORMAL)) |
2acca55e | 2110 | goto out; |
21aa9af0 | 2111 | |
fbd705a0 PZ |
2112 | trace_sched_waking(p); |
2113 | ||
e33a9bba TH |
2114 | if (!task_on_rq_queued(p)) { |
2115 | if (p->in_iowait) { | |
2116 | delayacct_blkio_end(); | |
2117 | atomic_dec(&rq->nr_iowait); | |
2118 | } | |
bce4dc80 | 2119 | ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK); |
e33a9bba | 2120 | } |
d7c01d27 | 2121 | |
d8ac8971 | 2122 | ttwu_do_wakeup(rq, p, 0, rf); |
4fa8d299 | 2123 | ttwu_stat(p, smp_processor_id(), 0); |
2acca55e PZ |
2124 | out: |
2125 | raw_spin_unlock(&p->pi_lock); | |
21aa9af0 TH |
2126 | } |
2127 | ||
50fa610a DH |
2128 | /** |
2129 | * wake_up_process - Wake up a specific process | |
2130 | * @p: The process to be woken up. | |
2131 | * | |
2132 | * Attempt to wake up the nominated process and move it to the set of runnable | |
e69f6186 YB |
2133 | * processes. |
2134 | * | |
2135 | * Return: 1 if the process was woken up, 0 if it was already running. | |
50fa610a DH |
2136 | * |
2137 | * It may be assumed that this function implies a write memory barrier before | |
2138 | * changing the task state if and only if any tasks are woken up. | |
2139 | */ | |
7ad5b3a5 | 2140 | int wake_up_process(struct task_struct *p) |
1da177e4 | 2141 | { |
9067ac85 | 2142 | return try_to_wake_up(p, TASK_NORMAL, 0); |
1da177e4 | 2143 | } |
1da177e4 LT |
2144 | EXPORT_SYMBOL(wake_up_process); |
2145 | ||
7ad5b3a5 | 2146 | int wake_up_state(struct task_struct *p, unsigned int state) |
1da177e4 LT |
2147 | { |
2148 | return try_to_wake_up(p, state, 0); | |
2149 | } | |
2150 | ||
1da177e4 LT |
2151 | /* |
2152 | * Perform scheduler related setup for a newly forked process p. | |
2153 | * p is forked by current. | |
dd41f596 IM |
2154 | * |
2155 | * __sched_fork() is basic setup used by init_idle() too: | |
2156 | */ | |
5e1576ed | 2157 | static void __sched_fork(unsigned long clone_flags, struct task_struct *p) |
dd41f596 | 2158 | { |
fd2f4419 PZ |
2159 | p->on_rq = 0; |
2160 | ||
2161 | p->se.on_rq = 0; | |
dd41f596 IM |
2162 | p->se.exec_start = 0; |
2163 | p->se.sum_exec_runtime = 0; | |
f6cf891c | 2164 | p->se.prev_sum_exec_runtime = 0; |
6c594c21 | 2165 | p->se.nr_migrations = 0; |
da7a735e | 2166 | p->se.vruntime = 0; |
fd2f4419 | 2167 | INIT_LIST_HEAD(&p->se.group_node); |
6cfb0d5d | 2168 | |
ad936d86 BP |
2169 | #ifdef CONFIG_FAIR_GROUP_SCHED |
2170 | p->se.cfs_rq = NULL; | |
2171 | #endif | |
2172 | ||
6cfb0d5d | 2173 | #ifdef CONFIG_SCHEDSTATS |
cb251765 | 2174 | /* Even if schedstat is disabled, there should not be garbage */ |
41acab88 | 2175 | memset(&p->se.statistics, 0, sizeof(p->se.statistics)); |
6cfb0d5d | 2176 | #endif |
476d139c | 2177 | |
aab03e05 | 2178 | RB_CLEAR_NODE(&p->dl.rb_node); |
40767b0d | 2179 | init_dl_task_timer(&p->dl); |
209a0cbd | 2180 | init_dl_inactive_task_timer(&p->dl); |
a5e7be3b | 2181 | __dl_clear_params(p); |
aab03e05 | 2182 | |
fa717060 | 2183 | INIT_LIST_HEAD(&p->rt.run_list); |
ff77e468 PZ |
2184 | p->rt.timeout = 0; |
2185 | p->rt.time_slice = sched_rr_timeslice; | |
2186 | p->rt.on_rq = 0; | |
2187 | p->rt.on_list = 0; | |
476d139c | 2188 | |
e107be36 AK |
2189 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
2190 | INIT_HLIST_HEAD(&p->preempt_notifiers); | |
2191 | #endif | |
cbee9f88 PZ |
2192 | |
2193 | #ifdef CONFIG_NUMA_BALANCING | |
2194 | if (p->mm && atomic_read(&p->mm->mm_users) == 1) { | |
7e8d16b6 | 2195 | p->mm->numa_next_scan = jiffies + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); |
cbee9f88 PZ |
2196 | p->mm->numa_scan_seq = 0; |
2197 | } | |
2198 | ||
5e1576ed RR |
2199 | if (clone_flags & CLONE_VM) |
2200 | p->numa_preferred_nid = current->numa_preferred_nid; | |
2201 | else | |
2202 | p->numa_preferred_nid = -1; | |
2203 | ||
cbee9f88 PZ |
2204 | p->node_stamp = 0ULL; |
2205 | p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0; | |
4b96a29b | 2206 | p->numa_scan_period = sysctl_numa_balancing_scan_delay; |
cbee9f88 | 2207 | p->numa_work.next = &p->numa_work; |
44dba3d5 | 2208 | p->numa_faults = NULL; |
7e2703e6 RR |
2209 | p->last_task_numa_placement = 0; |
2210 | p->last_sum_exec_runtime = 0; | |
8c8a743c | 2211 | |
8c8a743c | 2212 | p->numa_group = NULL; |
cbee9f88 | 2213 | #endif /* CONFIG_NUMA_BALANCING */ |
dd41f596 IM |
2214 | } |
2215 | ||
2a595721 SD |
2216 | DEFINE_STATIC_KEY_FALSE(sched_numa_balancing); |
2217 | ||
1a687c2e | 2218 | #ifdef CONFIG_NUMA_BALANCING |
c3b9bc5b | 2219 | |
1a687c2e MG |
2220 | void set_numabalancing_state(bool enabled) |
2221 | { | |
2222 | if (enabled) | |
2a595721 | 2223 | static_branch_enable(&sched_numa_balancing); |
1a687c2e | 2224 | else |
2a595721 | 2225 | static_branch_disable(&sched_numa_balancing); |
1a687c2e | 2226 | } |
54a43d54 AK |
2227 | |
2228 | #ifdef CONFIG_PROC_SYSCTL | |
2229 | int sysctl_numa_balancing(struct ctl_table *table, int write, | |
2230 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2231 | { | |
2232 | struct ctl_table t; | |
2233 | int err; | |
2a595721 | 2234 | int state = static_branch_likely(&sched_numa_balancing); |
54a43d54 AK |
2235 | |
2236 | if (write && !capable(CAP_SYS_ADMIN)) | |
2237 | return -EPERM; | |
2238 | ||
2239 | t = *table; | |
2240 | t.data = &state; | |
2241 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2242 | if (err < 0) | |
2243 | return err; | |
2244 | if (write) | |
2245 | set_numabalancing_state(state); | |
2246 | return err; | |
2247 | } | |
2248 | #endif | |
2249 | #endif | |
dd41f596 | 2250 | |
4698f88c JP |
2251 | #ifdef CONFIG_SCHEDSTATS |
2252 | ||
cb251765 | 2253 | DEFINE_STATIC_KEY_FALSE(sched_schedstats); |
4698f88c | 2254 | static bool __initdata __sched_schedstats = false; |
cb251765 | 2255 | |
cb251765 MG |
2256 | static void set_schedstats(bool enabled) |
2257 | { | |
2258 | if (enabled) | |
2259 | static_branch_enable(&sched_schedstats); | |
2260 | else | |
2261 | static_branch_disable(&sched_schedstats); | |
2262 | } | |
2263 | ||
2264 | void force_schedstat_enabled(void) | |
2265 | { | |
2266 | if (!schedstat_enabled()) { | |
2267 | pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n"); | |
2268 | static_branch_enable(&sched_schedstats); | |
2269 | } | |
2270 | } | |
2271 | ||
2272 | static int __init setup_schedstats(char *str) | |
2273 | { | |
2274 | int ret = 0; | |
2275 | if (!str) | |
2276 | goto out; | |
2277 | ||
4698f88c JP |
2278 | /* |
2279 | * This code is called before jump labels have been set up, so we can't | |
2280 | * change the static branch directly just yet. Instead set a temporary | |
2281 | * variable so init_schedstats() can do it later. | |
2282 | */ | |
cb251765 | 2283 | if (!strcmp(str, "enable")) { |
4698f88c | 2284 | __sched_schedstats = true; |
cb251765 MG |
2285 | ret = 1; |
2286 | } else if (!strcmp(str, "disable")) { | |
4698f88c | 2287 | __sched_schedstats = false; |
cb251765 MG |
2288 | ret = 1; |
2289 | } | |
2290 | out: | |
2291 | if (!ret) | |
2292 | pr_warn("Unable to parse schedstats=\n"); | |
2293 | ||
2294 | return ret; | |
2295 | } | |
2296 | __setup("schedstats=", setup_schedstats); | |
2297 | ||
4698f88c JP |
2298 | static void __init init_schedstats(void) |
2299 | { | |
2300 | set_schedstats(__sched_schedstats); | |
2301 | } | |
2302 | ||
cb251765 MG |
2303 | #ifdef CONFIG_PROC_SYSCTL |
2304 | int sysctl_schedstats(struct ctl_table *table, int write, | |
2305 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
2306 | { | |
2307 | struct ctl_table t; | |
2308 | int err; | |
2309 | int state = static_branch_likely(&sched_schedstats); | |
2310 | ||
2311 | if (write && !capable(CAP_SYS_ADMIN)) | |
2312 | return -EPERM; | |
2313 | ||
2314 | t = *table; | |
2315 | t.data = &state; | |
2316 | err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); | |
2317 | if (err < 0) | |
2318 | return err; | |
2319 | if (write) | |
2320 | set_schedstats(state); | |
2321 | return err; | |
2322 | } | |
4698f88c JP |
2323 | #endif /* CONFIG_PROC_SYSCTL */ |
2324 | #else /* !CONFIG_SCHEDSTATS */ | |
2325 | static inline void init_schedstats(void) {} | |
2326 | #endif /* CONFIG_SCHEDSTATS */ | |
dd41f596 IM |
2327 | |
2328 | /* | |
2329 | * fork()/clone()-time setup: | |
2330 | */ | |
aab03e05 | 2331 | int sched_fork(unsigned long clone_flags, struct task_struct *p) |
dd41f596 | 2332 | { |
0122ec5b | 2333 | unsigned long flags; |
dd41f596 IM |
2334 | int cpu = get_cpu(); |
2335 | ||
5e1576ed | 2336 | __sched_fork(clone_flags, p); |
06b83b5f | 2337 | /* |
7dc603c9 | 2338 | * We mark the process as NEW here. This guarantees that |
06b83b5f PZ |
2339 | * nobody will actually run it, and a signal or other external |
2340 | * event cannot wake it up and insert it on the runqueue either. | |
2341 | */ | |
7dc603c9 | 2342 | p->state = TASK_NEW; |
dd41f596 | 2343 | |
c350a04e MG |
2344 | /* |
2345 | * Make sure we do not leak PI boosting priority to the child. | |
2346 | */ | |
2347 | p->prio = current->normal_prio; | |
2348 | ||
b9dc29e7 MG |
2349 | /* |
2350 | * Revert to default priority/policy on fork if requested. | |
2351 | */ | |
2352 | if (unlikely(p->sched_reset_on_fork)) { | |
aab03e05 | 2353 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
b9dc29e7 | 2354 | p->policy = SCHED_NORMAL; |
6c697bdf | 2355 | p->static_prio = NICE_TO_PRIO(0); |
c350a04e MG |
2356 | p->rt_priority = 0; |
2357 | } else if (PRIO_TO_NICE(p->static_prio) < 0) | |
2358 | p->static_prio = NICE_TO_PRIO(0); | |
2359 | ||
2360 | p->prio = p->normal_prio = __normal_prio(p); | |
2361 | set_load_weight(p); | |
6c697bdf | 2362 | |
b9dc29e7 MG |
2363 | /* |
2364 | * We don't need the reset flag anymore after the fork. It has | |
2365 | * fulfilled its duty: | |
2366 | */ | |
2367 | p->sched_reset_on_fork = 0; | |
2368 | } | |
ca94c442 | 2369 | |
aab03e05 DF |
2370 | if (dl_prio(p->prio)) { |
2371 | put_cpu(); | |
2372 | return -EAGAIN; | |
2373 | } else if (rt_prio(p->prio)) { | |
2374 | p->sched_class = &rt_sched_class; | |
2375 | } else { | |
2ddbf952 | 2376 | p->sched_class = &fair_sched_class; |
aab03e05 | 2377 | } |
b29739f9 | 2378 | |
7dc603c9 | 2379 | init_entity_runnable_average(&p->se); |
cd29fe6f | 2380 | |
86951599 PZ |
2381 | /* |
2382 | * The child is not yet in the pid-hash so no cgroup attach races, | |
2383 | * and the cgroup is pinned to this child due to cgroup_fork() | |
2384 | * is ran before sched_fork(). | |
2385 | * | |
2386 | * Silence PROVE_RCU. | |
2387 | */ | |
0122ec5b | 2388 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
e210bffd | 2389 | /* |
d1ccc66d | 2390 | * We're setting the CPU for the first time, we don't migrate, |
e210bffd PZ |
2391 | * so use __set_task_cpu(). |
2392 | */ | |
2393 | __set_task_cpu(p, cpu); | |
2394 | if (p->sched_class->task_fork) | |
2395 | p->sched_class->task_fork(p); | |
0122ec5b | 2396 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
5f3edc1b | 2397 | |
f6db8347 | 2398 | #ifdef CONFIG_SCHED_INFO |
dd41f596 | 2399 | if (likely(sched_info_on())) |
52f17b6c | 2400 | memset(&p->sched_info, 0, sizeof(p->sched_info)); |
1da177e4 | 2401 | #endif |
3ca7a440 PZ |
2402 | #if defined(CONFIG_SMP) |
2403 | p->on_cpu = 0; | |
4866cde0 | 2404 | #endif |
01028747 | 2405 | init_task_preempt_count(p); |
806c09a7 | 2406 | #ifdef CONFIG_SMP |
917b627d | 2407 | plist_node_init(&p->pushable_tasks, MAX_PRIO); |
1baca4ce | 2408 | RB_CLEAR_NODE(&p->pushable_dl_tasks); |
806c09a7 | 2409 | #endif |
917b627d | 2410 | |
476d139c | 2411 | put_cpu(); |
aab03e05 | 2412 | return 0; |
1da177e4 LT |
2413 | } |
2414 | ||
332ac17e DF |
2415 | unsigned long to_ratio(u64 period, u64 runtime) |
2416 | { | |
2417 | if (runtime == RUNTIME_INF) | |
c52f14d3 | 2418 | return BW_UNIT; |
332ac17e DF |
2419 | |
2420 | /* | |
2421 | * Doing this here saves a lot of checks in all | |
2422 | * the calling paths, and returning zero seems | |
2423 | * safe for them anyway. | |
2424 | */ | |
2425 | if (period == 0) | |
2426 | return 0; | |
2427 | ||
c52f14d3 | 2428 | return div64_u64(runtime << BW_SHIFT, period); |
332ac17e DF |
2429 | } |
2430 | ||
1da177e4 LT |
2431 | /* |
2432 | * wake_up_new_task - wake up a newly created task for the first time. | |
2433 | * | |
2434 | * This function will do some initial scheduler statistics housekeeping | |
2435 | * that must be done for every newly created context, then puts the task | |
2436 | * on the runqueue and wakes it. | |
2437 | */ | |
3e51e3ed | 2438 | void wake_up_new_task(struct task_struct *p) |
1da177e4 | 2439 | { |
eb580751 | 2440 | struct rq_flags rf; |
dd41f596 | 2441 | struct rq *rq; |
fabf318e | 2442 | |
eb580751 | 2443 | raw_spin_lock_irqsave(&p->pi_lock, rf.flags); |
7dc603c9 | 2444 | p->state = TASK_RUNNING; |
fabf318e PZ |
2445 | #ifdef CONFIG_SMP |
2446 | /* | |
2447 | * Fork balancing, do it here and not earlier because: | |
2448 | * - cpus_allowed can change in the fork path | |
d1ccc66d | 2449 | * - any previously selected CPU might disappear through hotplug |
e210bffd PZ |
2450 | * |
2451 | * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, | |
2452 | * as we're not fully set-up yet. | |
fabf318e | 2453 | */ |
e210bffd | 2454 | __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); |
0017d735 | 2455 | #endif |
b7fa30c9 | 2456 | rq = __task_rq_lock(p, &rf); |
4126bad6 | 2457 | update_rq_clock(rq); |
2b8c41da | 2458 | post_init_entity_util_avg(&p->se); |
0017d735 | 2459 | |
7a57f32a | 2460 | activate_task(rq, p, ENQUEUE_NOCLOCK); |
da0c1e65 | 2461 | p->on_rq = TASK_ON_RQ_QUEUED; |
fbd705a0 | 2462 | trace_sched_wakeup_new(p); |
a7558e01 | 2463 | check_preempt_curr(rq, p, WF_FORK); |
9a897c5a | 2464 | #ifdef CONFIG_SMP |
0aaafaab PZ |
2465 | if (p->sched_class->task_woken) { |
2466 | /* | |
2467 | * Nothing relies on rq->lock after this, so its fine to | |
2468 | * drop it. | |
2469 | */ | |
d8ac8971 | 2470 | rq_unpin_lock(rq, &rf); |
efbbd05a | 2471 | p->sched_class->task_woken(rq, p); |
d8ac8971 | 2472 | rq_repin_lock(rq, &rf); |
0aaafaab | 2473 | } |
9a897c5a | 2474 | #endif |
eb580751 | 2475 | task_rq_unlock(rq, p, &rf); |
1da177e4 LT |
2476 | } |
2477 | ||
e107be36 AK |
2478 | #ifdef CONFIG_PREEMPT_NOTIFIERS |
2479 | ||
1cde2930 PZ |
2480 | static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE; |
2481 | ||
2ecd9d29 PZ |
2482 | void preempt_notifier_inc(void) |
2483 | { | |
2484 | static_key_slow_inc(&preempt_notifier_key); | |
2485 | } | |
2486 | EXPORT_SYMBOL_GPL(preempt_notifier_inc); | |
2487 | ||
2488 | void preempt_notifier_dec(void) | |
2489 | { | |
2490 | static_key_slow_dec(&preempt_notifier_key); | |
2491 | } | |
2492 | EXPORT_SYMBOL_GPL(preempt_notifier_dec); | |
2493 | ||
e107be36 | 2494 | /** |
80dd99b3 | 2495 | * preempt_notifier_register - tell me when current is being preempted & rescheduled |
421cee29 | 2496 | * @notifier: notifier struct to register |
e107be36 AK |
2497 | */ |
2498 | void preempt_notifier_register(struct preempt_notifier *notifier) | |
2499 | { | |
2ecd9d29 PZ |
2500 | if (!static_key_false(&preempt_notifier_key)) |
2501 | WARN(1, "registering preempt_notifier while notifiers disabled\n"); | |
2502 | ||
e107be36 AK |
2503 | hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); |
2504 | } | |
2505 | EXPORT_SYMBOL_GPL(preempt_notifier_register); | |
2506 | ||
2507 | /** | |
2508 | * preempt_notifier_unregister - no longer interested in preemption notifications | |
421cee29 | 2509 | * @notifier: notifier struct to unregister |
e107be36 | 2510 | * |
d84525a8 | 2511 | * This is *not* safe to call from within a preemption notifier. |
e107be36 AK |
2512 | */ |
2513 | void preempt_notifier_unregister(struct preempt_notifier *notifier) | |
2514 | { | |
2515 | hlist_del(¬ifier->link); | |
2516 | } | |
2517 | EXPORT_SYMBOL_GPL(preempt_notifier_unregister); | |
2518 | ||
1cde2930 | 2519 | static void __fire_sched_in_preempt_notifiers(struct task_struct *curr) |
e107be36 AK |
2520 | { |
2521 | struct preempt_notifier *notifier; | |
e107be36 | 2522 | |
b67bfe0d | 2523 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
e107be36 AK |
2524 | notifier->ops->sched_in(notifier, raw_smp_processor_id()); |
2525 | } | |
2526 | ||
1cde2930 PZ |
2527 | static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
2528 | { | |
2529 | if (static_key_false(&preempt_notifier_key)) | |
2530 | __fire_sched_in_preempt_notifiers(curr); | |
2531 | } | |
2532 | ||
e107be36 | 2533 | static void |
1cde2930 PZ |
2534 | __fire_sched_out_preempt_notifiers(struct task_struct *curr, |
2535 | struct task_struct *next) | |
e107be36 AK |
2536 | { |
2537 | struct preempt_notifier *notifier; | |
e107be36 | 2538 | |
b67bfe0d | 2539 | hlist_for_each_entry(notifier, &curr->preempt_notifiers, link) |
e107be36 AK |
2540 | notifier->ops->sched_out(notifier, next); |
2541 | } | |
2542 | ||
1cde2930 PZ |
2543 | static __always_inline void |
2544 | fire_sched_out_preempt_notifiers(struct task_struct *curr, | |
2545 | struct task_struct *next) | |
2546 | { | |
2547 | if (static_key_false(&preempt_notifier_key)) | |
2548 | __fire_sched_out_preempt_notifiers(curr, next); | |
2549 | } | |
2550 | ||
6d6bc0ad | 2551 | #else /* !CONFIG_PREEMPT_NOTIFIERS */ |
e107be36 | 2552 | |
1cde2930 | 2553 | static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr) |
e107be36 AK |
2554 | { |
2555 | } | |
2556 | ||
1cde2930 | 2557 | static inline void |
e107be36 AK |
2558 | fire_sched_out_preempt_notifiers(struct task_struct *curr, |
2559 | struct task_struct *next) | |
2560 | { | |
2561 | } | |
2562 | ||
6d6bc0ad | 2563 | #endif /* CONFIG_PREEMPT_NOTIFIERS */ |
e107be36 | 2564 | |
4866cde0 NP |
2565 | /** |
2566 | * prepare_task_switch - prepare to switch tasks | |
2567 | * @rq: the runqueue preparing to switch | |
421cee29 | 2568 | * @prev: the current task that is being switched out |
4866cde0 NP |
2569 | * @next: the task we are going to switch to. |
2570 | * | |
2571 | * This is called with the rq lock held and interrupts off. It must | |
2572 | * be paired with a subsequent finish_task_switch after the context | |
2573 | * switch. | |
2574 | * | |
2575 | * prepare_task_switch sets up locking and calls architecture specific | |
2576 | * hooks. | |
2577 | */ | |
e107be36 AK |
2578 | static inline void |
2579 | prepare_task_switch(struct rq *rq, struct task_struct *prev, | |
2580 | struct task_struct *next) | |
4866cde0 | 2581 | { |
43148951 | 2582 | sched_info_switch(rq, prev, next); |
fe4b04fa | 2583 | perf_event_task_sched_out(prev, next); |
e107be36 | 2584 | fire_sched_out_preempt_notifiers(prev, next); |
4866cde0 NP |
2585 | prepare_lock_switch(rq, next); |
2586 | prepare_arch_switch(next); | |
2587 | } | |
2588 | ||
1da177e4 LT |
2589 | /** |
2590 | * finish_task_switch - clean up after a task-switch | |
2591 | * @prev: the thread we just switched away from. | |
2592 | * | |
4866cde0 NP |
2593 | * finish_task_switch must be called after the context switch, paired |
2594 | * with a prepare_task_switch call before the context switch. | |
2595 | * finish_task_switch will reconcile locking set up by prepare_task_switch, | |
2596 | * and do any other architecture-specific cleanup actions. | |
1da177e4 LT |
2597 | * |
2598 | * Note that we may have delayed dropping an mm in context_switch(). If | |
41a2d6cf | 2599 | * so, we finish that here outside of the runqueue lock. (Doing it |
1da177e4 LT |
2600 | * with the lock held can cause deadlocks; see schedule() for |
2601 | * details.) | |
dfa50b60 ON |
2602 | * |
2603 | * The context switch have flipped the stack from under us and restored the | |
2604 | * local variables which were saved when this task called schedule() in the | |
2605 | * past. prev == current is still correct but we need to recalculate this_rq | |
2606 | * because prev may have moved to another CPU. | |
1da177e4 | 2607 | */ |
dfa50b60 | 2608 | static struct rq *finish_task_switch(struct task_struct *prev) |
1da177e4 LT |
2609 | __releases(rq->lock) |
2610 | { | |
dfa50b60 | 2611 | struct rq *rq = this_rq(); |
1da177e4 | 2612 | struct mm_struct *mm = rq->prev_mm; |
55a101f8 | 2613 | long prev_state; |
1da177e4 | 2614 | |
609ca066 PZ |
2615 | /* |
2616 | * The previous task will have left us with a preempt_count of 2 | |
2617 | * because it left us after: | |
2618 | * | |
2619 | * schedule() | |
2620 | * preempt_disable(); // 1 | |
2621 | * __schedule() | |
2622 | * raw_spin_lock_irq(&rq->lock) // 2 | |
2623 | * | |
2624 | * Also, see FORK_PREEMPT_COUNT. | |
2625 | */ | |
e2bf1c4b PZ |
2626 | if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET, |
2627 | "corrupted preempt_count: %s/%d/0x%x\n", | |
2628 | current->comm, current->pid, preempt_count())) | |
2629 | preempt_count_set(FORK_PREEMPT_COUNT); | |
609ca066 | 2630 | |
1da177e4 LT |
2631 | rq->prev_mm = NULL; |
2632 | ||
2633 | /* | |
2634 | * A task struct has one reference for the use as "current". | |
c394cc9f | 2635 | * If a task dies, then it sets TASK_DEAD in tsk->state and calls |
55a101f8 ON |
2636 | * schedule one last time. The schedule call will never return, and |
2637 | * the scheduled task must drop that reference. | |
95913d97 PZ |
2638 | * |
2639 | * We must observe prev->state before clearing prev->on_cpu (in | |
2640 | * finish_lock_switch), otherwise a concurrent wakeup can get prev | |
2641 | * running on another CPU and we could rave with its RUNNING -> DEAD | |
2642 | * transition, resulting in a double drop. | |
1da177e4 | 2643 | */ |
55a101f8 | 2644 | prev_state = prev->state; |
bf9fae9f | 2645 | vtime_task_switch(prev); |
a8d757ef | 2646 | perf_event_task_sched_in(prev, current); |
22e4ebb9 MD |
2647 | /* |
2648 | * The membarrier system call requires a full memory barrier | |
2649 | * after storing to rq->curr, before going back to user-space. | |
2650 | * | |
2651 | * TODO: This smp_mb__after_unlock_lock can go away if PPC end | |
2652 | * up adding a full barrier to switch_mm(), or we should figure | |
2653 | * out if a smp_mb__after_unlock_lock is really the proper API | |
2654 | * to use. | |
2655 | */ | |
2656 | smp_mb__after_unlock_lock(); | |
4866cde0 | 2657 | finish_lock_switch(rq, prev); |
01f23e16 | 2658 | finish_arch_post_lock_switch(); |
e8fa1362 | 2659 | |
e107be36 | 2660 | fire_sched_in_preempt_notifiers(current); |
1da177e4 LT |
2661 | if (mm) |
2662 | mmdrop(mm); | |
c394cc9f | 2663 | if (unlikely(prev_state == TASK_DEAD)) { |
e6c390f2 DF |
2664 | if (prev->sched_class->task_dead) |
2665 | prev->sched_class->task_dead(prev); | |
2666 | ||
c6fd91f0 | 2667 | /* |
2668 | * Remove function-return probe instances associated with this | |
2669 | * task and put them back on the free list. | |
9761eea8 | 2670 | */ |
c6fd91f0 | 2671 | kprobe_flush_task(prev); |
68f24b08 AL |
2672 | |
2673 | /* Task is done with its stack. */ | |
2674 | put_task_stack(prev); | |
2675 | ||
1da177e4 | 2676 | put_task_struct(prev); |
c6fd91f0 | 2677 | } |
99e5ada9 | 2678 | |
de734f89 | 2679 | tick_nohz_task_switch(); |
dfa50b60 | 2680 | return rq; |
1da177e4 LT |
2681 | } |
2682 | ||
3f029d3c GH |
2683 | #ifdef CONFIG_SMP |
2684 | ||
3f029d3c | 2685 | /* rq->lock is NOT held, but preemption is disabled */ |
e3fca9e7 | 2686 | static void __balance_callback(struct rq *rq) |
3f029d3c | 2687 | { |
e3fca9e7 PZ |
2688 | struct callback_head *head, *next; |
2689 | void (*func)(struct rq *rq); | |
2690 | unsigned long flags; | |
3f029d3c | 2691 | |
e3fca9e7 PZ |
2692 | raw_spin_lock_irqsave(&rq->lock, flags); |
2693 | head = rq->balance_callback; | |
2694 | rq->balance_callback = NULL; | |
2695 | while (head) { | |
2696 | func = (void (*)(struct rq *))head->func; | |
2697 | next = head->next; | |
2698 | head->next = NULL; | |
2699 | head = next; | |
3f029d3c | 2700 | |
e3fca9e7 | 2701 | func(rq); |
3f029d3c | 2702 | } |
e3fca9e7 PZ |
2703 | raw_spin_unlock_irqrestore(&rq->lock, flags); |
2704 | } | |
2705 | ||
2706 | static inline void balance_callback(struct rq *rq) | |
2707 | { | |
2708 | if (unlikely(rq->balance_callback)) | |
2709 | __balance_callback(rq); | |
3f029d3c GH |
2710 | } |
2711 | ||
2712 | #else | |
da19ab51 | 2713 | |
e3fca9e7 | 2714 | static inline void balance_callback(struct rq *rq) |
3f029d3c | 2715 | { |
1da177e4 LT |
2716 | } |
2717 | ||
3f029d3c GH |
2718 | #endif |
2719 | ||
1da177e4 LT |
2720 | /** |
2721 | * schedule_tail - first thing a freshly forked thread must call. | |
2722 | * @prev: the thread we just switched away from. | |
2723 | */ | |
722a9f92 | 2724 | asmlinkage __visible void schedule_tail(struct task_struct *prev) |
1da177e4 LT |
2725 | __releases(rq->lock) |
2726 | { | |
1a43a14a | 2727 | struct rq *rq; |
da19ab51 | 2728 | |
609ca066 PZ |
2729 | /* |
2730 | * New tasks start with FORK_PREEMPT_COUNT, see there and | |
2731 | * finish_task_switch() for details. | |
2732 | * | |
2733 | * finish_task_switch() will drop rq->lock() and lower preempt_count | |
2734 | * and the preempt_enable() will end up enabling preemption (on | |
2735 | * PREEMPT_COUNT kernels). | |
2736 | */ | |
2737 | ||
dfa50b60 | 2738 | rq = finish_task_switch(prev); |
e3fca9e7 | 2739 | balance_callback(rq); |
1a43a14a | 2740 | preempt_enable(); |
70b97a7f | 2741 | |
1da177e4 | 2742 | if (current->set_child_tid) |
b488893a | 2743 | put_user(task_pid_vnr(current), current->set_child_tid); |
1da177e4 LT |
2744 | } |
2745 | ||
2746 | /* | |
dfa50b60 | 2747 | * context_switch - switch to the new MM and the new thread's register state. |
1da177e4 | 2748 | */ |
04936948 | 2749 | static __always_inline struct rq * |
70b97a7f | 2750 | context_switch(struct rq *rq, struct task_struct *prev, |
d8ac8971 | 2751 | struct task_struct *next, struct rq_flags *rf) |
1da177e4 | 2752 | { |
dd41f596 | 2753 | struct mm_struct *mm, *oldmm; |
1da177e4 | 2754 | |
e107be36 | 2755 | prepare_task_switch(rq, prev, next); |
fe4b04fa | 2756 | |
dd41f596 IM |
2757 | mm = next->mm; |
2758 | oldmm = prev->active_mm; | |
9226d125 ZA |
2759 | /* |
2760 | * For paravirt, this is coupled with an exit in switch_to to | |
2761 | * combine the page table reload and the switch backend into | |
2762 | * one hypercall. | |
2763 | */ | |
224101ed | 2764 | arch_start_context_switch(prev); |
9226d125 | 2765 | |
31915ab4 | 2766 | if (!mm) { |
1da177e4 | 2767 | next->active_mm = oldmm; |
f1f10076 | 2768 | mmgrab(oldmm); |
1da177e4 LT |
2769 | enter_lazy_tlb(oldmm, next); |
2770 | } else | |
f98db601 | 2771 | switch_mm_irqs_off(oldmm, mm, next); |
1da177e4 | 2772 | |
31915ab4 | 2773 | if (!prev->mm) { |
1da177e4 | 2774 | prev->active_mm = NULL; |
1da177e4 LT |
2775 | rq->prev_mm = oldmm; |
2776 | } | |
92509b73 | 2777 | |
cb42c9a3 | 2778 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
92509b73 | 2779 | |
3a5f5e48 IM |
2780 | /* |
2781 | * Since the runqueue lock will be released by the next | |
2782 | * task (which is an invalid locking op but in the case | |
2783 | * of the scheduler it's an obvious special-case), so we | |
2784 | * do an early lockdep release here: | |
2785 | */ | |
d8ac8971 | 2786 | rq_unpin_lock(rq, rf); |
8a25d5de | 2787 | spin_release(&rq->lock.dep_map, 1, _THIS_IP_); |
1da177e4 LT |
2788 | |
2789 | /* Here we just switch the register state and the stack. */ | |
2790 | switch_to(prev, next, prev); | |
dd41f596 | 2791 | barrier(); |
dfa50b60 ON |
2792 | |
2793 | return finish_task_switch(prev); | |
1da177e4 LT |
2794 | } |
2795 | ||
2796 | /* | |
1c3e8264 | 2797 | * nr_running and nr_context_switches: |
1da177e4 LT |
2798 | * |
2799 | * externally visible scheduler statistics: current number of runnable | |
1c3e8264 | 2800 | * threads, total number of context switches performed since bootup. |
1da177e4 LT |
2801 | */ |
2802 | unsigned long nr_running(void) | |
2803 | { | |
2804 | unsigned long i, sum = 0; | |
2805 | ||
2806 | for_each_online_cpu(i) | |
2807 | sum += cpu_rq(i)->nr_running; | |
2808 | ||
2809 | return sum; | |
f711f609 | 2810 | } |
1da177e4 | 2811 | |
2ee507c4 | 2812 | /* |
d1ccc66d | 2813 | * Check if only the current task is running on the CPU. |
00cc1633 DD |
2814 | * |
2815 | * Caution: this function does not check that the caller has disabled | |
2816 | * preemption, thus the result might have a time-of-check-to-time-of-use | |
2817 | * race. The caller is responsible to use it correctly, for example: | |
2818 | * | |
2819 | * - from a non-preemptable section (of course) | |
2820 | * | |
2821 | * - from a thread that is bound to a single CPU | |
2822 | * | |
2823 | * - in a loop with very short iterations (e.g. a polling loop) | |
2ee507c4 TC |
2824 | */ |
2825 | bool single_task_running(void) | |
2826 | { | |
00cc1633 | 2827 | return raw_rq()->nr_running == 1; |
2ee507c4 TC |
2828 | } |
2829 | EXPORT_SYMBOL(single_task_running); | |
2830 | ||
1da177e4 | 2831 | unsigned long long nr_context_switches(void) |
46cb4b7c | 2832 | { |
cc94abfc SR |
2833 | int i; |
2834 | unsigned long long sum = 0; | |
46cb4b7c | 2835 | |
0a945022 | 2836 | for_each_possible_cpu(i) |
1da177e4 | 2837 | sum += cpu_rq(i)->nr_switches; |
46cb4b7c | 2838 | |
1da177e4 LT |
2839 | return sum; |
2840 | } | |
483b4ee6 | 2841 | |
e33a9bba TH |
2842 | /* |
2843 | * IO-wait accounting, and how its mostly bollocks (on SMP). | |
2844 | * | |
2845 | * The idea behind IO-wait account is to account the idle time that we could | |
2846 | * have spend running if it were not for IO. That is, if we were to improve the | |
2847 | * storage performance, we'd have a proportional reduction in IO-wait time. | |
2848 | * | |
2849 | * This all works nicely on UP, where, when a task blocks on IO, we account | |
2850 | * idle time as IO-wait, because if the storage were faster, it could've been | |
2851 | * running and we'd not be idle. | |
2852 | * | |
2853 | * This has been extended to SMP, by doing the same for each CPU. This however | |
2854 | * is broken. | |
2855 | * | |
2856 | * Imagine for instance the case where two tasks block on one CPU, only the one | |
2857 | * CPU will have IO-wait accounted, while the other has regular idle. Even | |
2858 | * though, if the storage were faster, both could've ran at the same time, | |
2859 | * utilising both CPUs. | |
2860 | * | |
2861 | * This means, that when looking globally, the current IO-wait accounting on | |
2862 | * SMP is a lower bound, by reason of under accounting. | |
2863 | * | |
2864 | * Worse, since the numbers are provided per CPU, they are sometimes | |
2865 | * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly | |
2866 | * associated with any one particular CPU, it can wake to another CPU than it | |
2867 | * blocked on. This means the per CPU IO-wait number is meaningless. | |
2868 | * | |
2869 | * Task CPU affinities can make all that even more 'interesting'. | |
2870 | */ | |
2871 | ||
1da177e4 LT |
2872 | unsigned long nr_iowait(void) |
2873 | { | |
2874 | unsigned long i, sum = 0; | |
483b4ee6 | 2875 | |
0a945022 | 2876 | for_each_possible_cpu(i) |
1da177e4 | 2877 | sum += atomic_read(&cpu_rq(i)->nr_iowait); |
46cb4b7c | 2878 | |
1da177e4 LT |
2879 | return sum; |
2880 | } | |
483b4ee6 | 2881 | |
e33a9bba TH |
2882 | /* |
2883 | * Consumers of these two interfaces, like for example the cpufreq menu | |
2884 | * governor are using nonsensical data. Boosting frequency for a CPU that has | |
2885 | * IO-wait which might not even end up running the task when it does become | |
2886 | * runnable. | |
2887 | */ | |
2888 | ||
8c215bd3 | 2889 | unsigned long nr_iowait_cpu(int cpu) |
69d25870 | 2890 | { |
8c215bd3 | 2891 | struct rq *this = cpu_rq(cpu); |
69d25870 AV |
2892 | return atomic_read(&this->nr_iowait); |
2893 | } | |
46cb4b7c | 2894 | |
372ba8cb MG |
2895 | void get_iowait_load(unsigned long *nr_waiters, unsigned long *load) |
2896 | { | |
3289bdb4 PZ |
2897 | struct rq *rq = this_rq(); |
2898 | *nr_waiters = atomic_read(&rq->nr_iowait); | |
2899 | *load = rq->load.weight; | |
372ba8cb MG |
2900 | } |
2901 | ||
dd41f596 | 2902 | #ifdef CONFIG_SMP |
8a0be9ef | 2903 | |
46cb4b7c | 2904 | /* |
38022906 PZ |
2905 | * sched_exec - execve() is a valuable balancing opportunity, because at |
2906 | * this point the task has the smallest effective memory and cache footprint. | |
46cb4b7c | 2907 | */ |
38022906 | 2908 | void sched_exec(void) |
46cb4b7c | 2909 | { |
38022906 | 2910 | struct task_struct *p = current; |
1da177e4 | 2911 | unsigned long flags; |
0017d735 | 2912 | int dest_cpu; |
46cb4b7c | 2913 | |
8f42ced9 | 2914 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
ac66f547 | 2915 | dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0); |
0017d735 PZ |
2916 | if (dest_cpu == smp_processor_id()) |
2917 | goto unlock; | |
38022906 | 2918 | |
8f42ced9 | 2919 | if (likely(cpu_active(dest_cpu))) { |
969c7921 | 2920 | struct migration_arg arg = { p, dest_cpu }; |
46cb4b7c | 2921 | |
8f42ced9 PZ |
2922 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
2923 | stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); | |
1da177e4 LT |
2924 | return; |
2925 | } | |
0017d735 | 2926 | unlock: |
8f42ced9 | 2927 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 | 2928 | } |
dd41f596 | 2929 | |
1da177e4 LT |
2930 | #endif |
2931 | ||
1da177e4 | 2932 | DEFINE_PER_CPU(struct kernel_stat, kstat); |
3292beb3 | 2933 | DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); |
1da177e4 LT |
2934 | |
2935 | EXPORT_PER_CPU_SYMBOL(kstat); | |
3292beb3 | 2936 | EXPORT_PER_CPU_SYMBOL(kernel_cpustat); |
1da177e4 | 2937 | |
6075620b GG |
2938 | /* |
2939 | * The function fair_sched_class.update_curr accesses the struct curr | |
2940 | * and its field curr->exec_start; when called from task_sched_runtime(), | |
2941 | * we observe a high rate of cache misses in practice. | |
2942 | * Prefetching this data results in improved performance. | |
2943 | */ | |
2944 | static inline void prefetch_curr_exec_start(struct task_struct *p) | |
2945 | { | |
2946 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
2947 | struct sched_entity *curr = (&p->se)->cfs_rq->curr; | |
2948 | #else | |
2949 | struct sched_entity *curr = (&task_rq(p)->cfs)->curr; | |
2950 | #endif | |
2951 | prefetch(curr); | |
2952 | prefetch(&curr->exec_start); | |
2953 | } | |
2954 | ||
c5f8d995 HS |
2955 | /* |
2956 | * Return accounted runtime for the task. | |
2957 | * In case the task is currently running, return the runtime plus current's | |
2958 | * pending runtime that have not been accounted yet. | |
2959 | */ | |
2960 | unsigned long long task_sched_runtime(struct task_struct *p) | |
2961 | { | |
eb580751 | 2962 | struct rq_flags rf; |
c5f8d995 | 2963 | struct rq *rq; |
6e998916 | 2964 | u64 ns; |
c5f8d995 | 2965 | |
911b2898 PZ |
2966 | #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) |
2967 | /* | |
2968 | * 64-bit doesn't need locks to atomically read a 64bit value. | |
2969 | * So we have a optimization chance when the task's delta_exec is 0. | |
2970 | * Reading ->on_cpu is racy, but this is ok. | |
2971 | * | |
d1ccc66d IM |
2972 | * If we race with it leaving CPU, we'll take a lock. So we're correct. |
2973 | * If we race with it entering CPU, unaccounted time is 0. This is | |
911b2898 | 2974 | * indistinguishable from the read occurring a few cycles earlier. |
4036ac15 MG |
2975 | * If we see ->on_cpu without ->on_rq, the task is leaving, and has |
2976 | * been accounted, so we're correct here as well. | |
911b2898 | 2977 | */ |
da0c1e65 | 2978 | if (!p->on_cpu || !task_on_rq_queued(p)) |
911b2898 PZ |
2979 | return p->se.sum_exec_runtime; |
2980 | #endif | |
2981 | ||
eb580751 | 2982 | rq = task_rq_lock(p, &rf); |
6e998916 SG |
2983 | /* |
2984 | * Must be ->curr _and_ ->on_rq. If dequeued, we would | |
2985 | * project cycles that may never be accounted to this | |
2986 | * thread, breaking clock_gettime(). | |
2987 | */ | |
2988 | if (task_current(rq, p) && task_on_rq_queued(p)) { | |
6075620b | 2989 | prefetch_curr_exec_start(p); |
6e998916 SG |
2990 | update_rq_clock(rq); |
2991 | p->sched_class->update_curr(rq); | |
2992 | } | |
2993 | ns = p->se.sum_exec_runtime; | |
eb580751 | 2994 | task_rq_unlock(rq, p, &rf); |
c5f8d995 HS |
2995 | |
2996 | return ns; | |
2997 | } | |
48f24c4d | 2998 | |
7835b98b CL |
2999 | /* |
3000 | * This function gets called by the timer code, with HZ frequency. | |
3001 | * We call it with interrupts disabled. | |
7835b98b CL |
3002 | */ |
3003 | void scheduler_tick(void) | |
3004 | { | |
7835b98b CL |
3005 | int cpu = smp_processor_id(); |
3006 | struct rq *rq = cpu_rq(cpu); | |
dd41f596 | 3007 | struct task_struct *curr = rq->curr; |
8a8c69c3 | 3008 | struct rq_flags rf; |
3e51f33f PZ |
3009 | |
3010 | sched_clock_tick(); | |
dd41f596 | 3011 | |
8a8c69c3 PZ |
3012 | rq_lock(rq, &rf); |
3013 | ||
3e51f33f | 3014 | update_rq_clock(rq); |
fa85ae24 | 3015 | curr->sched_class->task_tick(rq, curr, 0); |
cee1afce | 3016 | cpu_load_update_active(rq); |
3289bdb4 | 3017 | calc_global_load_tick(rq); |
8a8c69c3 PZ |
3018 | |
3019 | rq_unlock(rq, &rf); | |
7835b98b | 3020 | |
e9d2b064 | 3021 | perf_event_task_tick(); |
e220d2dc | 3022 | |
e418e1c2 | 3023 | #ifdef CONFIG_SMP |
6eb57e0d | 3024 | rq->idle_balance = idle_cpu(cpu); |
7caff66f | 3025 | trigger_load_balance(rq); |
e418e1c2 | 3026 | #endif |
265f22a9 | 3027 | rq_last_tick_reset(rq); |
1da177e4 LT |
3028 | } |
3029 | ||
265f22a9 FW |
3030 | #ifdef CONFIG_NO_HZ_FULL |
3031 | /** | |
3032 | * scheduler_tick_max_deferment | |
3033 | * | |
3034 | * Keep at least one tick per second when a single | |
3035 | * active task is running because the scheduler doesn't | |
3036 | * yet completely support full dynticks environment. | |
3037 | * | |
3038 | * This makes sure that uptime, CFS vruntime, load | |
3039 | * balancing, etc... continue to move forward, even | |
3040 | * with a very low granularity. | |
e69f6186 YB |
3041 | * |
3042 | * Return: Maximum deferment in nanoseconds. | |
265f22a9 FW |
3043 | */ |
3044 | u64 scheduler_tick_max_deferment(void) | |
3045 | { | |
3046 | struct rq *rq = this_rq(); | |
316c1608 | 3047 | unsigned long next, now = READ_ONCE(jiffies); |
265f22a9 FW |
3048 | |
3049 | next = rq->last_sched_tick + HZ; | |
3050 | ||
3051 | if (time_before_eq(next, now)) | |
3052 | return 0; | |
3053 | ||
8fe8ff09 | 3054 | return jiffies_to_nsecs(next - now); |
1da177e4 | 3055 | } |
265f22a9 | 3056 | #endif |
1da177e4 | 3057 | |
7e49fcce SR |
3058 | #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ |
3059 | defined(CONFIG_PREEMPT_TRACER)) | |
47252cfb SR |
3060 | /* |
3061 | * If the value passed in is equal to the current preempt count | |
3062 | * then we just disabled preemption. Start timing the latency. | |
3063 | */ | |
3064 | static inline void preempt_latency_start(int val) | |
3065 | { | |
3066 | if (preempt_count() == val) { | |
3067 | unsigned long ip = get_lock_parent_ip(); | |
3068 | #ifdef CONFIG_DEBUG_PREEMPT | |
3069 | current->preempt_disable_ip = ip; | |
3070 | #endif | |
3071 | trace_preempt_off(CALLER_ADDR0, ip); | |
3072 | } | |
3073 | } | |
7e49fcce | 3074 | |
edafe3a5 | 3075 | void preempt_count_add(int val) |
1da177e4 | 3076 | { |
6cd8a4bb | 3077 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3078 | /* |
3079 | * Underflow? | |
3080 | */ | |
9a11b49a IM |
3081 | if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) |
3082 | return; | |
6cd8a4bb | 3083 | #endif |
bdb43806 | 3084 | __preempt_count_add(val); |
6cd8a4bb | 3085 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3086 | /* |
3087 | * Spinlock count overflowing soon? | |
3088 | */ | |
33859f7f MOS |
3089 | DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= |
3090 | PREEMPT_MASK - 10); | |
6cd8a4bb | 3091 | #endif |
47252cfb | 3092 | preempt_latency_start(val); |
1da177e4 | 3093 | } |
bdb43806 | 3094 | EXPORT_SYMBOL(preempt_count_add); |
edafe3a5 | 3095 | NOKPROBE_SYMBOL(preempt_count_add); |
1da177e4 | 3096 | |
47252cfb SR |
3097 | /* |
3098 | * If the value passed in equals to the current preempt count | |
3099 | * then we just enabled preemption. Stop timing the latency. | |
3100 | */ | |
3101 | static inline void preempt_latency_stop(int val) | |
3102 | { | |
3103 | if (preempt_count() == val) | |
3104 | trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); | |
3105 | } | |
3106 | ||
edafe3a5 | 3107 | void preempt_count_sub(int val) |
1da177e4 | 3108 | { |
6cd8a4bb | 3109 | #ifdef CONFIG_DEBUG_PREEMPT |
1da177e4 LT |
3110 | /* |
3111 | * Underflow? | |
3112 | */ | |
01e3eb82 | 3113 | if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) |
9a11b49a | 3114 | return; |
1da177e4 LT |
3115 | /* |
3116 | * Is the spinlock portion underflowing? | |
3117 | */ | |
9a11b49a IM |
3118 | if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && |
3119 | !(preempt_count() & PREEMPT_MASK))) | |
3120 | return; | |
6cd8a4bb | 3121 | #endif |
9a11b49a | 3122 | |
47252cfb | 3123 | preempt_latency_stop(val); |
bdb43806 | 3124 | __preempt_count_sub(val); |
1da177e4 | 3125 | } |
bdb43806 | 3126 | EXPORT_SYMBOL(preempt_count_sub); |
edafe3a5 | 3127 | NOKPROBE_SYMBOL(preempt_count_sub); |
1da177e4 | 3128 | |
47252cfb SR |
3129 | #else |
3130 | static inline void preempt_latency_start(int val) { } | |
3131 | static inline void preempt_latency_stop(int val) { } | |
1da177e4 LT |
3132 | #endif |
3133 | ||
59ddbcb2 IM |
3134 | static inline unsigned long get_preempt_disable_ip(struct task_struct *p) |
3135 | { | |
3136 | #ifdef CONFIG_DEBUG_PREEMPT | |
3137 | return p->preempt_disable_ip; | |
3138 | #else | |
3139 | return 0; | |
3140 | #endif | |
3141 | } | |
3142 | ||
1da177e4 | 3143 | /* |
dd41f596 | 3144 | * Print scheduling while atomic bug: |
1da177e4 | 3145 | */ |
dd41f596 | 3146 | static noinline void __schedule_bug(struct task_struct *prev) |
1da177e4 | 3147 | { |
d1c6d149 VN |
3148 | /* Save this before calling printk(), since that will clobber it */ |
3149 | unsigned long preempt_disable_ip = get_preempt_disable_ip(current); | |
3150 | ||
664dfa65 DJ |
3151 | if (oops_in_progress) |
3152 | return; | |
3153 | ||
3df0fc5b PZ |
3154 | printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", |
3155 | prev->comm, prev->pid, preempt_count()); | |
838225b4 | 3156 | |
dd41f596 | 3157 | debug_show_held_locks(prev); |
e21f5b15 | 3158 | print_modules(); |
dd41f596 IM |
3159 | if (irqs_disabled()) |
3160 | print_irqtrace_events(prev); | |
d1c6d149 VN |
3161 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
3162 | && in_atomic_preempt_off()) { | |
8f47b187 | 3163 | pr_err("Preemption disabled at:"); |
d1c6d149 | 3164 | print_ip_sym(preempt_disable_ip); |
8f47b187 TG |
3165 | pr_cont("\n"); |
3166 | } | |
748c7201 DBO |
3167 | if (panic_on_warn) |
3168 | panic("scheduling while atomic\n"); | |
3169 | ||
6135fc1e | 3170 | dump_stack(); |
373d4d09 | 3171 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
dd41f596 | 3172 | } |
1da177e4 | 3173 | |
dd41f596 IM |
3174 | /* |
3175 | * Various schedule()-time debugging checks and statistics: | |
3176 | */ | |
3177 | static inline void schedule_debug(struct task_struct *prev) | |
3178 | { | |
0d9e2632 | 3179 | #ifdef CONFIG_SCHED_STACK_END_CHECK |
29d64551 JH |
3180 | if (task_stack_end_corrupted(prev)) |
3181 | panic("corrupted stack end detected inside scheduler\n"); | |
0d9e2632 | 3182 | #endif |
b99def8b | 3183 | |
1dc0fffc | 3184 | if (unlikely(in_atomic_preempt_off())) { |
dd41f596 | 3185 | __schedule_bug(prev); |
1dc0fffc PZ |
3186 | preempt_count_set(PREEMPT_DISABLED); |
3187 | } | |
b3fbab05 | 3188 | rcu_sleep_check(); |
dd41f596 | 3189 | |
1da177e4 LT |
3190 | profile_hit(SCHED_PROFILING, __builtin_return_address(0)); |
3191 | ||
ae92882e | 3192 | schedstat_inc(this_rq()->sched_count); |
dd41f596 IM |
3193 | } |
3194 | ||
3195 | /* | |
3196 | * Pick up the highest-prio task: | |
3197 | */ | |
3198 | static inline struct task_struct * | |
d8ac8971 | 3199 | pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
dd41f596 | 3200 | { |
49ee5768 | 3201 | const struct sched_class *class; |
dd41f596 | 3202 | struct task_struct *p; |
1da177e4 LT |
3203 | |
3204 | /* | |
0ba87bb2 PZ |
3205 | * Optimization: we know that if all tasks are in the fair class we can |
3206 | * call that function directly, but only if the @prev task wasn't of a | |
3207 | * higher scheduling class, because otherwise those loose the | |
3208 | * opportunity to pull in more work from other CPUs. | |
1da177e4 | 3209 | */ |
0ba87bb2 PZ |
3210 | if (likely((prev->sched_class == &idle_sched_class || |
3211 | prev->sched_class == &fair_sched_class) && | |
3212 | rq->nr_running == rq->cfs.h_nr_running)) { | |
3213 | ||
d8ac8971 | 3214 | p = fair_sched_class.pick_next_task(rq, prev, rf); |
6ccdc84b PZ |
3215 | if (unlikely(p == RETRY_TASK)) |
3216 | goto again; | |
3217 | ||
d1ccc66d | 3218 | /* Assumes fair_sched_class->next == idle_sched_class */ |
6ccdc84b | 3219 | if (unlikely(!p)) |
d8ac8971 | 3220 | p = idle_sched_class.pick_next_task(rq, prev, rf); |
6ccdc84b PZ |
3221 | |
3222 | return p; | |
1da177e4 LT |
3223 | } |
3224 | ||
37e117c0 | 3225 | again: |
34f971f6 | 3226 | for_each_class(class) { |
d8ac8971 | 3227 | p = class->pick_next_task(rq, prev, rf); |
37e117c0 PZ |
3228 | if (p) { |
3229 | if (unlikely(p == RETRY_TASK)) | |
3230 | goto again; | |
dd41f596 | 3231 | return p; |
37e117c0 | 3232 | } |
dd41f596 | 3233 | } |
34f971f6 | 3234 | |
d1ccc66d IM |
3235 | /* The idle class should always have a runnable task: */ |
3236 | BUG(); | |
dd41f596 | 3237 | } |
1da177e4 | 3238 | |
dd41f596 | 3239 | /* |
c259e01a | 3240 | * __schedule() is the main scheduler function. |
edde96ea PE |
3241 | * |
3242 | * The main means of driving the scheduler and thus entering this function are: | |
3243 | * | |
3244 | * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. | |
3245 | * | |
3246 | * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return | |
3247 | * paths. For example, see arch/x86/entry_64.S. | |
3248 | * | |
3249 | * To drive preemption between tasks, the scheduler sets the flag in timer | |
3250 | * interrupt handler scheduler_tick(). | |
3251 | * | |
3252 | * 3. Wakeups don't really cause entry into schedule(). They add a | |
3253 | * task to the run-queue and that's it. | |
3254 | * | |
3255 | * Now, if the new task added to the run-queue preempts the current | |
3256 | * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets | |
3257 | * called on the nearest possible occasion: | |
3258 | * | |
3259 | * - If the kernel is preemptible (CONFIG_PREEMPT=y): | |
3260 | * | |
3261 | * - in syscall or exception context, at the next outmost | |
3262 | * preempt_enable(). (this might be as soon as the wake_up()'s | |
3263 | * spin_unlock()!) | |
3264 | * | |
3265 | * - in IRQ context, return from interrupt-handler to | |
3266 | * preemptible context | |
3267 | * | |
3268 | * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) | |
3269 | * then at the next: | |
3270 | * | |
3271 | * - cond_resched() call | |
3272 | * - explicit schedule() call | |
3273 | * - return from syscall or exception to user-space | |
3274 | * - return from interrupt-handler to user-space | |
bfd9b2b5 | 3275 | * |
b30f0e3f | 3276 | * WARNING: must be called with preemption disabled! |
dd41f596 | 3277 | */ |
499d7955 | 3278 | static void __sched notrace __schedule(bool preempt) |
dd41f596 IM |
3279 | { |
3280 | struct task_struct *prev, *next; | |
67ca7bde | 3281 | unsigned long *switch_count; |
d8ac8971 | 3282 | struct rq_flags rf; |
dd41f596 | 3283 | struct rq *rq; |
31656519 | 3284 | int cpu; |
dd41f596 | 3285 | |
dd41f596 IM |
3286 | cpu = smp_processor_id(); |
3287 | rq = cpu_rq(cpu); | |
dd41f596 | 3288 | prev = rq->curr; |
dd41f596 | 3289 | |
dd41f596 | 3290 | schedule_debug(prev); |
1da177e4 | 3291 | |
31656519 | 3292 | if (sched_feat(HRTICK)) |
f333fdc9 | 3293 | hrtick_clear(rq); |
8f4d37ec | 3294 | |
46a5d164 | 3295 | local_irq_disable(); |
bcbfdd01 | 3296 | rcu_note_context_switch(preempt); |
46a5d164 | 3297 | |
e0acd0a6 ON |
3298 | /* |
3299 | * Make sure that signal_pending_state()->signal_pending() below | |
3300 | * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE) | |
3301 | * done by the caller to avoid the race with signal_wake_up(). | |
3302 | */ | |
8a8c69c3 | 3303 | rq_lock(rq, &rf); |
d89e588c | 3304 | smp_mb__after_spinlock(); |
1da177e4 | 3305 | |
d1ccc66d IM |
3306 | /* Promote REQ to ACT */ |
3307 | rq->clock_update_flags <<= 1; | |
bce4dc80 | 3308 | update_rq_clock(rq); |
9edfbfed | 3309 | |
246d86b5 | 3310 | switch_count = &prev->nivcsw; |
fc13aeba | 3311 | if (!preempt && prev->state) { |
21aa9af0 | 3312 | if (unlikely(signal_pending_state(prev->state, prev))) { |
1da177e4 | 3313 | prev->state = TASK_RUNNING; |
21aa9af0 | 3314 | } else { |
bce4dc80 | 3315 | deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK); |
2acca55e PZ |
3316 | prev->on_rq = 0; |
3317 | ||
e33a9bba TH |
3318 | if (prev->in_iowait) { |
3319 | atomic_inc(&rq->nr_iowait); | |
3320 | delayacct_blkio_start(); | |
3321 | } | |
3322 | ||
21aa9af0 | 3323 | /* |
2acca55e PZ |
3324 | * If a worker went to sleep, notify and ask workqueue |
3325 | * whether it wants to wake up a task to maintain | |
3326 | * concurrency. | |
21aa9af0 TH |
3327 | */ |
3328 | if (prev->flags & PF_WQ_WORKER) { | |
3329 | struct task_struct *to_wakeup; | |
3330 | ||
9b7f6597 | 3331 | to_wakeup = wq_worker_sleeping(prev); |
21aa9af0 | 3332 | if (to_wakeup) |
d8ac8971 | 3333 | try_to_wake_up_local(to_wakeup, &rf); |
21aa9af0 | 3334 | } |
21aa9af0 | 3335 | } |
dd41f596 | 3336 | switch_count = &prev->nvcsw; |
1da177e4 LT |
3337 | } |
3338 | ||
d8ac8971 | 3339 | next = pick_next_task(rq, prev, &rf); |
f26f9aff | 3340 | clear_tsk_need_resched(prev); |
f27dde8d | 3341 | clear_preempt_need_resched(); |
1da177e4 | 3342 | |
1da177e4 | 3343 | if (likely(prev != next)) { |
1da177e4 LT |
3344 | rq->nr_switches++; |
3345 | rq->curr = next; | |
22e4ebb9 MD |
3346 | /* |
3347 | * The membarrier system call requires each architecture | |
3348 | * to have a full memory barrier after updating | |
3349 | * rq->curr, before returning to user-space. For TSO | |
3350 | * (e.g. x86), the architecture must provide its own | |
3351 | * barrier in switch_mm(). For weakly ordered machines | |
3352 | * for which spin_unlock() acts as a full memory | |
3353 | * barrier, finish_lock_switch() in common code takes | |
3354 | * care of this barrier. For weakly ordered machines for | |
3355 | * which spin_unlock() acts as a RELEASE barrier (only | |
3356 | * arm64 and PowerPC), arm64 has a full barrier in | |
3357 | * switch_to(), and PowerPC has | |
3358 | * smp_mb__after_unlock_lock() before | |
3359 | * finish_lock_switch(). | |
3360 | */ | |
1da177e4 LT |
3361 | ++*switch_count; |
3362 | ||
c73464b1 | 3363 | trace_sched_switch(preempt, prev, next); |
d1ccc66d IM |
3364 | |
3365 | /* Also unlocks the rq: */ | |
3366 | rq = context_switch(rq, prev, next, &rf); | |
cbce1a68 | 3367 | } else { |
cb42c9a3 | 3368 | rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP); |
8a8c69c3 | 3369 | rq_unlock_irq(rq, &rf); |
cbce1a68 | 3370 | } |
1da177e4 | 3371 | |
e3fca9e7 | 3372 | balance_callback(rq); |
1da177e4 | 3373 | } |
c259e01a | 3374 | |
9af6528e PZ |
3375 | void __noreturn do_task_dead(void) |
3376 | { | |
3377 | /* | |
3378 | * The setting of TASK_RUNNING by try_to_wake_up() may be delayed | |
3379 | * when the following two conditions become true. | |
3380 | * - There is race condition of mmap_sem (It is acquired by | |
3381 | * exit_mm()), and | |
3382 | * - SMI occurs before setting TASK_RUNINNG. | |
3383 | * (or hypervisor of virtual machine switches to other guest) | |
3384 | * As a result, we may become TASK_RUNNING after becoming TASK_DEAD | |
3385 | * | |
3386 | * To avoid it, we have to wait for releasing tsk->pi_lock which | |
3387 | * is held by try_to_wake_up() | |
3388 | */ | |
23a9b748 PM |
3389 | raw_spin_lock_irq(¤t->pi_lock); |
3390 | raw_spin_unlock_irq(¤t->pi_lock); | |
9af6528e | 3391 | |
d1ccc66d | 3392 | /* Causes final put_task_struct in finish_task_switch(): */ |
9af6528e | 3393 | __set_current_state(TASK_DEAD); |
d1ccc66d IM |
3394 | |
3395 | /* Tell freezer to ignore us: */ | |
3396 | current->flags |= PF_NOFREEZE; | |
3397 | ||
9af6528e PZ |
3398 | __schedule(false); |
3399 | BUG(); | |
d1ccc66d IM |
3400 | |
3401 | /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */ | |
9af6528e | 3402 | for (;;) |
d1ccc66d | 3403 | cpu_relax(); |
9af6528e PZ |
3404 | } |
3405 | ||
9c40cef2 TG |
3406 | static inline void sched_submit_work(struct task_struct *tsk) |
3407 | { | |
3c7d5184 | 3408 | if (!tsk->state || tsk_is_pi_blocked(tsk)) |
9c40cef2 TG |
3409 | return; |
3410 | /* | |
3411 | * If we are going to sleep and we have plugged IO queued, | |
3412 | * make sure to submit it to avoid deadlocks. | |
3413 | */ | |
3414 | if (blk_needs_flush_plug(tsk)) | |
3415 | blk_schedule_flush_plug(tsk); | |
3416 | } | |
3417 | ||
722a9f92 | 3418 | asmlinkage __visible void __sched schedule(void) |
c259e01a | 3419 | { |
9c40cef2 TG |
3420 | struct task_struct *tsk = current; |
3421 | ||
3422 | sched_submit_work(tsk); | |
bfd9b2b5 | 3423 | do { |
b30f0e3f | 3424 | preempt_disable(); |
fc13aeba | 3425 | __schedule(false); |
b30f0e3f | 3426 | sched_preempt_enable_no_resched(); |
bfd9b2b5 | 3427 | } while (need_resched()); |
c259e01a | 3428 | } |
1da177e4 LT |
3429 | EXPORT_SYMBOL(schedule); |
3430 | ||
8663effb SRV |
3431 | /* |
3432 | * synchronize_rcu_tasks() makes sure that no task is stuck in preempted | |
3433 | * state (have scheduled out non-voluntarily) by making sure that all | |
3434 | * tasks have either left the run queue or have gone into user space. | |
3435 | * As idle tasks do not do either, they must not ever be preempted | |
3436 | * (schedule out non-voluntarily). | |
3437 | * | |
3438 | * schedule_idle() is similar to schedule_preempt_disable() except that it | |
3439 | * never enables preemption because it does not call sched_submit_work(). | |
3440 | */ | |
3441 | void __sched schedule_idle(void) | |
3442 | { | |
3443 | /* | |
3444 | * As this skips calling sched_submit_work(), which the idle task does | |
3445 | * regardless because that function is a nop when the task is in a | |
3446 | * TASK_RUNNING state, make sure this isn't used someplace that the | |
3447 | * current task can be in any other state. Note, idle is always in the | |
3448 | * TASK_RUNNING state. | |
3449 | */ | |
3450 | WARN_ON_ONCE(current->state); | |
3451 | do { | |
3452 | __schedule(false); | |
3453 | } while (need_resched()); | |
3454 | } | |
3455 | ||
91d1aa43 | 3456 | #ifdef CONFIG_CONTEXT_TRACKING |
722a9f92 | 3457 | asmlinkage __visible void __sched schedule_user(void) |
20ab65e3 FW |
3458 | { |
3459 | /* | |
3460 | * If we come here after a random call to set_need_resched(), | |
3461 | * or we have been woken up remotely but the IPI has not yet arrived, | |
3462 | * we haven't yet exited the RCU idle mode. Do it here manually until | |
3463 | * we find a better solution. | |
7cc78f8f AL |
3464 | * |
3465 | * NB: There are buggy callers of this function. Ideally we | |
c467ea76 | 3466 | * should warn if prev_state != CONTEXT_USER, but that will trigger |
7cc78f8f | 3467 | * too frequently to make sense yet. |
20ab65e3 | 3468 | */ |
7cc78f8f | 3469 | enum ctx_state prev_state = exception_enter(); |
20ab65e3 | 3470 | schedule(); |
7cc78f8f | 3471 | exception_exit(prev_state); |
20ab65e3 FW |
3472 | } |
3473 | #endif | |
3474 | ||
c5491ea7 TG |
3475 | /** |
3476 | * schedule_preempt_disabled - called with preemption disabled | |
3477 | * | |
3478 | * Returns with preemption disabled. Note: preempt_count must be 1 | |
3479 | */ | |
3480 | void __sched schedule_preempt_disabled(void) | |
3481 | { | |
ba74c144 | 3482 | sched_preempt_enable_no_resched(); |
c5491ea7 TG |
3483 | schedule(); |
3484 | preempt_disable(); | |
3485 | } | |
3486 | ||
06b1f808 | 3487 | static void __sched notrace preempt_schedule_common(void) |
a18b5d01 FW |
3488 | { |
3489 | do { | |
47252cfb SR |
3490 | /* |
3491 | * Because the function tracer can trace preempt_count_sub() | |
3492 | * and it also uses preempt_enable/disable_notrace(), if | |
3493 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3494 | * by the function tracer will call this function again and | |
3495 | * cause infinite recursion. | |
3496 | * | |
3497 | * Preemption must be disabled here before the function | |
3498 | * tracer can trace. Break up preempt_disable() into two | |
3499 | * calls. One to disable preemption without fear of being | |
3500 | * traced. The other to still record the preemption latency, | |
3501 | * which can also be traced by the function tracer. | |
3502 | */ | |
499d7955 | 3503 | preempt_disable_notrace(); |
47252cfb | 3504 | preempt_latency_start(1); |
fc13aeba | 3505 | __schedule(true); |
47252cfb | 3506 | preempt_latency_stop(1); |
499d7955 | 3507 | preempt_enable_no_resched_notrace(); |
a18b5d01 FW |
3508 | |
3509 | /* | |
3510 | * Check again in case we missed a preemption opportunity | |
3511 | * between schedule and now. | |
3512 | */ | |
a18b5d01 FW |
3513 | } while (need_resched()); |
3514 | } | |
3515 | ||
1da177e4 LT |
3516 | #ifdef CONFIG_PREEMPT |
3517 | /* | |
2ed6e34f | 3518 | * this is the entry point to schedule() from in-kernel preemption |
41a2d6cf | 3519 | * off of preempt_enable. Kernel preemptions off return from interrupt |
1da177e4 LT |
3520 | * occur there and call schedule directly. |
3521 | */ | |
722a9f92 | 3522 | asmlinkage __visible void __sched notrace preempt_schedule(void) |
1da177e4 | 3523 | { |
1da177e4 LT |
3524 | /* |
3525 | * If there is a non-zero preempt_count or interrupts are disabled, | |
41a2d6cf | 3526 | * we do not want to preempt the current task. Just return.. |
1da177e4 | 3527 | */ |
fbb00b56 | 3528 | if (likely(!preemptible())) |
1da177e4 LT |
3529 | return; |
3530 | ||
a18b5d01 | 3531 | preempt_schedule_common(); |
1da177e4 | 3532 | } |
376e2424 | 3533 | NOKPROBE_SYMBOL(preempt_schedule); |
1da177e4 | 3534 | EXPORT_SYMBOL(preempt_schedule); |
009f60e2 | 3535 | |
009f60e2 | 3536 | /** |
4eaca0a8 | 3537 | * preempt_schedule_notrace - preempt_schedule called by tracing |
009f60e2 ON |
3538 | * |
3539 | * The tracing infrastructure uses preempt_enable_notrace to prevent | |
3540 | * recursion and tracing preempt enabling caused by the tracing | |
3541 | * infrastructure itself. But as tracing can happen in areas coming | |
3542 | * from userspace or just about to enter userspace, a preempt enable | |
3543 | * can occur before user_exit() is called. This will cause the scheduler | |
3544 | * to be called when the system is still in usermode. | |
3545 | * | |
3546 | * To prevent this, the preempt_enable_notrace will use this function | |
3547 | * instead of preempt_schedule() to exit user context if needed before | |
3548 | * calling the scheduler. | |
3549 | */ | |
4eaca0a8 | 3550 | asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) |
009f60e2 ON |
3551 | { |
3552 | enum ctx_state prev_ctx; | |
3553 | ||
3554 | if (likely(!preemptible())) | |
3555 | return; | |
3556 | ||
3557 | do { | |
47252cfb SR |
3558 | /* |
3559 | * Because the function tracer can trace preempt_count_sub() | |
3560 | * and it also uses preempt_enable/disable_notrace(), if | |
3561 | * NEED_RESCHED is set, the preempt_enable_notrace() called | |
3562 | * by the function tracer will call this function again and | |
3563 | * cause infinite recursion. | |
3564 | * | |
3565 | * Preemption must be disabled here before the function | |
3566 | * tracer can trace. Break up preempt_disable() into two | |
3567 | * calls. One to disable preemption without fear of being | |
3568 | * traced. The other to still record the preemption latency, | |
3569 | * which can also be traced by the function tracer. | |
3570 | */ | |
3d8f74dd | 3571 | preempt_disable_notrace(); |
47252cfb | 3572 | preempt_latency_start(1); |
009f60e2 ON |
3573 | /* |
3574 | * Needs preempt disabled in case user_exit() is traced | |
3575 | * and the tracer calls preempt_enable_notrace() causing | |
3576 | * an infinite recursion. | |
3577 | */ | |
3578 | prev_ctx = exception_enter(); | |
fc13aeba | 3579 | __schedule(true); |
009f60e2 ON |
3580 | exception_exit(prev_ctx); |
3581 | ||
47252cfb | 3582 | preempt_latency_stop(1); |
3d8f74dd | 3583 | preempt_enable_no_resched_notrace(); |
009f60e2 ON |
3584 | } while (need_resched()); |
3585 | } | |
4eaca0a8 | 3586 | EXPORT_SYMBOL_GPL(preempt_schedule_notrace); |
009f60e2 | 3587 | |
32e475d7 | 3588 | #endif /* CONFIG_PREEMPT */ |
1da177e4 LT |
3589 | |
3590 | /* | |
2ed6e34f | 3591 | * this is the entry point to schedule() from kernel preemption |
1da177e4 LT |
3592 | * off of irq context. |
3593 | * Note, that this is called and return with irqs disabled. This will | |
3594 | * protect us against recursive calling from irq. | |
3595 | */ | |
722a9f92 | 3596 | asmlinkage __visible void __sched preempt_schedule_irq(void) |
1da177e4 | 3597 | { |
b22366cd | 3598 | enum ctx_state prev_state; |
6478d880 | 3599 | |
2ed6e34f | 3600 | /* Catch callers which need to be fixed */ |
f27dde8d | 3601 | BUG_ON(preempt_count() || !irqs_disabled()); |
1da177e4 | 3602 | |
b22366cd FW |
3603 | prev_state = exception_enter(); |
3604 | ||
3a5c359a | 3605 | do { |
3d8f74dd | 3606 | preempt_disable(); |
3a5c359a | 3607 | local_irq_enable(); |
fc13aeba | 3608 | __schedule(true); |
3a5c359a | 3609 | local_irq_disable(); |
3d8f74dd | 3610 | sched_preempt_enable_no_resched(); |
5ed0cec0 | 3611 | } while (need_resched()); |
b22366cd FW |
3612 | |
3613 | exception_exit(prev_state); | |
1da177e4 LT |
3614 | } |
3615 | ||
ac6424b9 | 3616 | int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags, |
95cdf3b7 | 3617 | void *key) |
1da177e4 | 3618 | { |
63859d4f | 3619 | return try_to_wake_up(curr->private, mode, wake_flags); |
1da177e4 | 3620 | } |
1da177e4 LT |
3621 | EXPORT_SYMBOL(default_wake_function); |
3622 | ||
b29739f9 IM |
3623 | #ifdef CONFIG_RT_MUTEXES |
3624 | ||
acd58620 PZ |
3625 | static inline int __rt_effective_prio(struct task_struct *pi_task, int prio) |
3626 | { | |
3627 | if (pi_task) | |
3628 | prio = min(prio, pi_task->prio); | |
3629 | ||
3630 | return prio; | |
3631 | } | |
3632 | ||
3633 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3634 | { | |
3635 | struct task_struct *pi_task = rt_mutex_get_top_task(p); | |
3636 | ||
3637 | return __rt_effective_prio(pi_task, prio); | |
3638 | } | |
3639 | ||
b29739f9 IM |
3640 | /* |
3641 | * rt_mutex_setprio - set the current priority of a task | |
acd58620 PZ |
3642 | * @p: task to boost |
3643 | * @pi_task: donor task | |
b29739f9 IM |
3644 | * |
3645 | * This function changes the 'effective' priority of a task. It does | |
3646 | * not touch ->normal_prio like __setscheduler(). | |
3647 | * | |
c365c292 TG |
3648 | * Used by the rt_mutex code to implement priority inheritance |
3649 | * logic. Call site only calls if the priority of the task changed. | |
b29739f9 | 3650 | */ |
acd58620 | 3651 | void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) |
b29739f9 | 3652 | { |
acd58620 | 3653 | int prio, oldprio, queued, running, queue_flag = |
7a57f32a | 3654 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
83ab0aa0 | 3655 | const struct sched_class *prev_class; |
eb580751 PZ |
3656 | struct rq_flags rf; |
3657 | struct rq *rq; | |
b29739f9 | 3658 | |
acd58620 PZ |
3659 | /* XXX used to be waiter->prio, not waiter->task->prio */ |
3660 | prio = __rt_effective_prio(pi_task, p->normal_prio); | |
3661 | ||
3662 | /* | |
3663 | * If nothing changed; bail early. | |
3664 | */ | |
3665 | if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio)) | |
3666 | return; | |
b29739f9 | 3667 | |
eb580751 | 3668 | rq = __task_rq_lock(p, &rf); |
80f5c1b8 | 3669 | update_rq_clock(rq); |
acd58620 PZ |
3670 | /* |
3671 | * Set under pi_lock && rq->lock, such that the value can be used under | |
3672 | * either lock. | |
3673 | * | |
3674 | * Note that there is loads of tricky to make this pointer cache work | |
3675 | * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to | |
3676 | * ensure a task is de-boosted (pi_task is set to NULL) before the | |
3677 | * task is allowed to run again (and can exit). This ensures the pointer | |
3678 | * points to a blocked task -- which guaratees the task is present. | |
3679 | */ | |
3680 | p->pi_top_task = pi_task; | |
3681 | ||
3682 | /* | |
3683 | * For FIFO/RR we only need to set prio, if that matches we're done. | |
3684 | */ | |
3685 | if (prio == p->prio && !dl_prio(prio)) | |
3686 | goto out_unlock; | |
b29739f9 | 3687 | |
1c4dd99b TG |
3688 | /* |
3689 | * Idle task boosting is a nono in general. There is one | |
3690 | * exception, when PREEMPT_RT and NOHZ is active: | |
3691 | * | |
3692 | * The idle task calls get_next_timer_interrupt() and holds | |
3693 | * the timer wheel base->lock on the CPU and another CPU wants | |
3694 | * to access the timer (probably to cancel it). We can safely | |
3695 | * ignore the boosting request, as the idle CPU runs this code | |
3696 | * with interrupts disabled and will complete the lock | |
3697 | * protected section without being interrupted. So there is no | |
3698 | * real need to boost. | |
3699 | */ | |
3700 | if (unlikely(p == rq->idle)) { | |
3701 | WARN_ON(p != rq->curr); | |
3702 | WARN_ON(p->pi_blocked_on); | |
3703 | goto out_unlock; | |
3704 | } | |
3705 | ||
b91473ff | 3706 | trace_sched_pi_setprio(p, pi_task); |
d5f9f942 | 3707 | oldprio = p->prio; |
ff77e468 PZ |
3708 | |
3709 | if (oldprio == prio) | |
3710 | queue_flag &= ~DEQUEUE_MOVE; | |
3711 | ||
83ab0aa0 | 3712 | prev_class = p->sched_class; |
da0c1e65 | 3713 | queued = task_on_rq_queued(p); |
051a1d1a | 3714 | running = task_current(rq, p); |
da0c1e65 | 3715 | if (queued) |
ff77e468 | 3716 | dequeue_task(rq, p, queue_flag); |
0e1f3483 | 3717 | if (running) |
f3cd1c4e | 3718 | put_prev_task(rq, p); |
dd41f596 | 3719 | |
2d3d891d DF |
3720 | /* |
3721 | * Boosting condition are: | |
3722 | * 1. -rt task is running and holds mutex A | |
3723 | * --> -dl task blocks on mutex A | |
3724 | * | |
3725 | * 2. -dl task is running and holds mutex A | |
3726 | * --> -dl task blocks on mutex A and could preempt the | |
3727 | * running task | |
3728 | */ | |
3729 | if (dl_prio(prio)) { | |
466af29b ON |
3730 | if (!dl_prio(p->normal_prio) || |
3731 | (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) { | |
2d3d891d | 3732 | p->dl.dl_boosted = 1; |
ff77e468 | 3733 | queue_flag |= ENQUEUE_REPLENISH; |
2d3d891d DF |
3734 | } else |
3735 | p->dl.dl_boosted = 0; | |
aab03e05 | 3736 | p->sched_class = &dl_sched_class; |
2d3d891d DF |
3737 | } else if (rt_prio(prio)) { |
3738 | if (dl_prio(oldprio)) | |
3739 | p->dl.dl_boosted = 0; | |
3740 | if (oldprio < prio) | |
ff77e468 | 3741 | queue_flag |= ENQUEUE_HEAD; |
dd41f596 | 3742 | p->sched_class = &rt_sched_class; |
2d3d891d DF |
3743 | } else { |
3744 | if (dl_prio(oldprio)) | |
3745 | p->dl.dl_boosted = 0; | |
746db944 BS |
3746 | if (rt_prio(oldprio)) |
3747 | p->rt.timeout = 0; | |
dd41f596 | 3748 | p->sched_class = &fair_sched_class; |
2d3d891d | 3749 | } |
dd41f596 | 3750 | |
b29739f9 IM |
3751 | p->prio = prio; |
3752 | ||
da0c1e65 | 3753 | if (queued) |
ff77e468 | 3754 | enqueue_task(rq, p, queue_flag); |
a399d233 | 3755 | if (running) |
b2bf6c31 | 3756 | set_curr_task(rq, p); |
cb469845 | 3757 | |
da7a735e | 3758 | check_class_changed(rq, p, prev_class, oldprio); |
1c4dd99b | 3759 | out_unlock: |
d1ccc66d IM |
3760 | /* Avoid rq from going away on us: */ |
3761 | preempt_disable(); | |
eb580751 | 3762 | __task_rq_unlock(rq, &rf); |
4c9a4bc8 PZ |
3763 | |
3764 | balance_callback(rq); | |
3765 | preempt_enable(); | |
b29739f9 | 3766 | } |
acd58620 PZ |
3767 | #else |
3768 | static inline int rt_effective_prio(struct task_struct *p, int prio) | |
3769 | { | |
3770 | return prio; | |
3771 | } | |
b29739f9 | 3772 | #endif |
d50dde5a | 3773 | |
36c8b586 | 3774 | void set_user_nice(struct task_struct *p, long nice) |
1da177e4 | 3775 | { |
49bd21ef PZ |
3776 | bool queued, running; |
3777 | int old_prio, delta; | |
eb580751 | 3778 | struct rq_flags rf; |
70b97a7f | 3779 | struct rq *rq; |
1da177e4 | 3780 | |
75e45d51 | 3781 | if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE) |
1da177e4 LT |
3782 | return; |
3783 | /* | |
3784 | * We have to be careful, if called from sys_setpriority(), | |
3785 | * the task might be in the middle of scheduling on another CPU. | |
3786 | */ | |
eb580751 | 3787 | rq = task_rq_lock(p, &rf); |
2fb8d367 PZ |
3788 | update_rq_clock(rq); |
3789 | ||
1da177e4 LT |
3790 | /* |
3791 | * The RT priorities are set via sched_setscheduler(), but we still | |
3792 | * allow the 'normal' nice value to be set - but as expected | |
3793 | * it wont have any effect on scheduling until the task is | |
aab03e05 | 3794 | * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR: |
1da177e4 | 3795 | */ |
aab03e05 | 3796 | if (task_has_dl_policy(p) || task_has_rt_policy(p)) { |
1da177e4 LT |
3797 | p->static_prio = NICE_TO_PRIO(nice); |
3798 | goto out_unlock; | |
3799 | } | |
da0c1e65 | 3800 | queued = task_on_rq_queued(p); |
49bd21ef | 3801 | running = task_current(rq, p); |
da0c1e65 | 3802 | if (queued) |
7a57f32a | 3803 | dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); |
49bd21ef PZ |
3804 | if (running) |
3805 | put_prev_task(rq, p); | |
1da177e4 | 3806 | |
1da177e4 | 3807 | p->static_prio = NICE_TO_PRIO(nice); |
2dd73a4f | 3808 | set_load_weight(p); |
b29739f9 IM |
3809 | old_prio = p->prio; |
3810 | p->prio = effective_prio(p); | |
3811 | delta = p->prio - old_prio; | |
1da177e4 | 3812 | |
da0c1e65 | 3813 | if (queued) { |
7134b3e9 | 3814 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
1da177e4 | 3815 | /* |
d5f9f942 AM |
3816 | * If the task increased its priority or is running and |
3817 | * lowered its priority, then reschedule its CPU: | |
1da177e4 | 3818 | */ |
d5f9f942 | 3819 | if (delta < 0 || (delta > 0 && task_running(rq, p))) |
8875125e | 3820 | resched_curr(rq); |
1da177e4 | 3821 | } |
49bd21ef PZ |
3822 | if (running) |
3823 | set_curr_task(rq, p); | |
1da177e4 | 3824 | out_unlock: |
eb580751 | 3825 | task_rq_unlock(rq, p, &rf); |
1da177e4 | 3826 | } |
1da177e4 LT |
3827 | EXPORT_SYMBOL(set_user_nice); |
3828 | ||
e43379f1 MM |
3829 | /* |
3830 | * can_nice - check if a task can reduce its nice value | |
3831 | * @p: task | |
3832 | * @nice: nice value | |
3833 | */ | |
36c8b586 | 3834 | int can_nice(const struct task_struct *p, const int nice) |
e43379f1 | 3835 | { |
d1ccc66d | 3836 | /* Convert nice value [19,-20] to rlimit style value [1,40]: */ |
7aa2c016 | 3837 | int nice_rlim = nice_to_rlimit(nice); |
48f24c4d | 3838 | |
78d7d407 | 3839 | return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || |
e43379f1 MM |
3840 | capable(CAP_SYS_NICE)); |
3841 | } | |
3842 | ||
1da177e4 LT |
3843 | #ifdef __ARCH_WANT_SYS_NICE |
3844 | ||
3845 | /* | |
3846 | * sys_nice - change the priority of the current process. | |
3847 | * @increment: priority increment | |
3848 | * | |
3849 | * sys_setpriority is a more generic, but much slower function that | |
3850 | * does similar things. | |
3851 | */ | |
5add95d4 | 3852 | SYSCALL_DEFINE1(nice, int, increment) |
1da177e4 | 3853 | { |
48f24c4d | 3854 | long nice, retval; |
1da177e4 LT |
3855 | |
3856 | /* | |
3857 | * Setpriority might change our priority at the same moment. | |
3858 | * We don't have to worry. Conceptually one call occurs first | |
3859 | * and we have a single winner. | |
3860 | */ | |
a9467fa3 | 3861 | increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH); |
d0ea0268 | 3862 | nice = task_nice(current) + increment; |
1da177e4 | 3863 | |
a9467fa3 | 3864 | nice = clamp_val(nice, MIN_NICE, MAX_NICE); |
e43379f1 MM |
3865 | if (increment < 0 && !can_nice(current, nice)) |
3866 | return -EPERM; | |
3867 | ||
1da177e4 LT |
3868 | retval = security_task_setnice(current, nice); |
3869 | if (retval) | |
3870 | return retval; | |
3871 | ||
3872 | set_user_nice(current, nice); | |
3873 | return 0; | |
3874 | } | |
3875 | ||
3876 | #endif | |
3877 | ||
3878 | /** | |
3879 | * task_prio - return the priority value of a given task. | |
3880 | * @p: the task in question. | |
3881 | * | |
e69f6186 | 3882 | * Return: The priority value as seen by users in /proc. |
1da177e4 LT |
3883 | * RT tasks are offset by -200. Normal tasks are centered |
3884 | * around 0, value goes from -16 to +15. | |
3885 | */ | |
36c8b586 | 3886 | int task_prio(const struct task_struct *p) |
1da177e4 LT |
3887 | { |
3888 | return p->prio - MAX_RT_PRIO; | |
3889 | } | |
3890 | ||
1da177e4 | 3891 | /** |
d1ccc66d | 3892 | * idle_cpu - is a given CPU idle currently? |
1da177e4 | 3893 | * @cpu: the processor in question. |
e69f6186 YB |
3894 | * |
3895 | * Return: 1 if the CPU is currently idle. 0 otherwise. | |
1da177e4 LT |
3896 | */ |
3897 | int idle_cpu(int cpu) | |
3898 | { | |
908a3283 TG |
3899 | struct rq *rq = cpu_rq(cpu); |
3900 | ||
3901 | if (rq->curr != rq->idle) | |
3902 | return 0; | |
3903 | ||
3904 | if (rq->nr_running) | |
3905 | return 0; | |
3906 | ||
3907 | #ifdef CONFIG_SMP | |
3908 | if (!llist_empty(&rq->wake_list)) | |
3909 | return 0; | |
3910 | #endif | |
3911 | ||
3912 | return 1; | |
1da177e4 LT |
3913 | } |
3914 | ||
1da177e4 | 3915 | /** |
d1ccc66d | 3916 | * idle_task - return the idle task for a given CPU. |
1da177e4 | 3917 | * @cpu: the processor in question. |
e69f6186 | 3918 | * |
d1ccc66d | 3919 | * Return: The idle task for the CPU @cpu. |
1da177e4 | 3920 | */ |
36c8b586 | 3921 | struct task_struct *idle_task(int cpu) |
1da177e4 LT |
3922 | { |
3923 | return cpu_rq(cpu)->idle; | |
3924 | } | |
3925 | ||
3926 | /** | |
3927 | * find_process_by_pid - find a process with a matching PID value. | |
3928 | * @pid: the pid in question. | |
e69f6186 YB |
3929 | * |
3930 | * The task of @pid, if found. %NULL otherwise. | |
1da177e4 | 3931 | */ |
a9957449 | 3932 | static struct task_struct *find_process_by_pid(pid_t pid) |
1da177e4 | 3933 | { |
228ebcbe | 3934 | return pid ? find_task_by_vpid(pid) : current; |
1da177e4 LT |
3935 | } |
3936 | ||
c13db6b1 SR |
3937 | /* |
3938 | * sched_setparam() passes in -1 for its policy, to let the functions | |
3939 | * it calls know not to change it. | |
3940 | */ | |
3941 | #define SETPARAM_POLICY -1 | |
3942 | ||
c365c292 TG |
3943 | static void __setscheduler_params(struct task_struct *p, |
3944 | const struct sched_attr *attr) | |
1da177e4 | 3945 | { |
d50dde5a DF |
3946 | int policy = attr->sched_policy; |
3947 | ||
c13db6b1 | 3948 | if (policy == SETPARAM_POLICY) |
39fd8fd2 PZ |
3949 | policy = p->policy; |
3950 | ||
1da177e4 | 3951 | p->policy = policy; |
d50dde5a | 3952 | |
aab03e05 DF |
3953 | if (dl_policy(policy)) |
3954 | __setparam_dl(p, attr); | |
39fd8fd2 | 3955 | else if (fair_policy(policy)) |
d50dde5a DF |
3956 | p->static_prio = NICE_TO_PRIO(attr->sched_nice); |
3957 | ||
39fd8fd2 PZ |
3958 | /* |
3959 | * __sched_setscheduler() ensures attr->sched_priority == 0 when | |
3960 | * !rt_policy. Always setting this ensures that things like | |
3961 | * getparam()/getattr() don't report silly values for !rt tasks. | |
3962 | */ | |
3963 | p->rt_priority = attr->sched_priority; | |
383afd09 | 3964 | p->normal_prio = normal_prio(p); |
c365c292 TG |
3965 | set_load_weight(p); |
3966 | } | |
39fd8fd2 | 3967 | |
c365c292 TG |
3968 | /* Actually do priority change: must hold pi & rq lock. */ |
3969 | static void __setscheduler(struct rq *rq, struct task_struct *p, | |
0782e63b | 3970 | const struct sched_attr *attr, bool keep_boost) |
c365c292 TG |
3971 | { |
3972 | __setscheduler_params(p, attr); | |
d50dde5a | 3973 | |
383afd09 | 3974 | /* |
0782e63b TG |
3975 | * Keep a potential priority boosting if called from |
3976 | * sched_setscheduler(). | |
383afd09 | 3977 | */ |
acd58620 | 3978 | p->prio = normal_prio(p); |
0782e63b | 3979 | if (keep_boost) |
acd58620 | 3980 | p->prio = rt_effective_prio(p, p->prio); |
383afd09 | 3981 | |
aab03e05 DF |
3982 | if (dl_prio(p->prio)) |
3983 | p->sched_class = &dl_sched_class; | |
3984 | else if (rt_prio(p->prio)) | |
ffd44db5 PZ |
3985 | p->sched_class = &rt_sched_class; |
3986 | else | |
3987 | p->sched_class = &fair_sched_class; | |
1da177e4 | 3988 | } |
aab03e05 | 3989 | |
c69e8d9c | 3990 | /* |
d1ccc66d | 3991 | * Check the target process has a UID that matches the current process's: |
c69e8d9c DH |
3992 | */ |
3993 | static bool check_same_owner(struct task_struct *p) | |
3994 | { | |
3995 | const struct cred *cred = current_cred(), *pcred; | |
3996 | bool match; | |
3997 | ||
3998 | rcu_read_lock(); | |
3999 | pcred = __task_cred(p); | |
9c806aa0 EB |
4000 | match = (uid_eq(cred->euid, pcred->euid) || |
4001 | uid_eq(cred->euid, pcred->uid)); | |
c69e8d9c DH |
4002 | rcu_read_unlock(); |
4003 | return match; | |
4004 | } | |
4005 | ||
d50dde5a DF |
4006 | static int __sched_setscheduler(struct task_struct *p, |
4007 | const struct sched_attr *attr, | |
dbc7f069 | 4008 | bool user, bool pi) |
1da177e4 | 4009 | { |
383afd09 SR |
4010 | int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : |
4011 | MAX_RT_PRIO - 1 - attr->sched_priority; | |
da0c1e65 | 4012 | int retval, oldprio, oldpolicy = -1, queued, running; |
0782e63b | 4013 | int new_effective_prio, policy = attr->sched_policy; |
83ab0aa0 | 4014 | const struct sched_class *prev_class; |
eb580751 | 4015 | struct rq_flags rf; |
ca94c442 | 4016 | int reset_on_fork; |
7a57f32a | 4017 | int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; |
eb580751 | 4018 | struct rq *rq; |
1da177e4 | 4019 | |
896bbb25 SRV |
4020 | /* The pi code expects interrupts enabled */ |
4021 | BUG_ON(pi && in_interrupt()); | |
1da177e4 | 4022 | recheck: |
d1ccc66d | 4023 | /* Double check policy once rq lock held: */ |
ca94c442 LP |
4024 | if (policy < 0) { |
4025 | reset_on_fork = p->sched_reset_on_fork; | |
1da177e4 | 4026 | policy = oldpolicy = p->policy; |
ca94c442 | 4027 | } else { |
7479f3c9 | 4028 | reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK); |
ca94c442 | 4029 | |
20f9cd2a | 4030 | if (!valid_policy(policy)) |
ca94c442 LP |
4031 | return -EINVAL; |
4032 | } | |
4033 | ||
2d4283e9 LA |
4034 | if (attr->sched_flags & |
4035 | ~(SCHED_FLAG_RESET_ON_FORK | SCHED_FLAG_RECLAIM)) | |
7479f3c9 PZ |
4036 | return -EINVAL; |
4037 | ||
1da177e4 LT |
4038 | /* |
4039 | * Valid priorities for SCHED_FIFO and SCHED_RR are | |
dd41f596 IM |
4040 | * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, |
4041 | * SCHED_BATCH and SCHED_IDLE is 0. | |
1da177e4 | 4042 | */ |
0bb040a4 | 4043 | if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || |
d50dde5a | 4044 | (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) |
1da177e4 | 4045 | return -EINVAL; |
aab03e05 DF |
4046 | if ((dl_policy(policy) && !__checkparam_dl(attr)) || |
4047 | (rt_policy(policy) != (attr->sched_priority != 0))) | |
1da177e4 LT |
4048 | return -EINVAL; |
4049 | ||
37e4ab3f OC |
4050 | /* |
4051 | * Allow unprivileged RT tasks to decrease priority: | |
4052 | */ | |
961ccddd | 4053 | if (user && !capable(CAP_SYS_NICE)) { |
d50dde5a | 4054 | if (fair_policy(policy)) { |
d0ea0268 | 4055 | if (attr->sched_nice < task_nice(p) && |
eaad4513 | 4056 | !can_nice(p, attr->sched_nice)) |
d50dde5a DF |
4057 | return -EPERM; |
4058 | } | |
4059 | ||
e05606d3 | 4060 | if (rt_policy(policy)) { |
a44702e8 ON |
4061 | unsigned long rlim_rtprio = |
4062 | task_rlimit(p, RLIMIT_RTPRIO); | |
8dc3e909 | 4063 | |
d1ccc66d | 4064 | /* Can't set/change the rt policy: */ |
8dc3e909 ON |
4065 | if (policy != p->policy && !rlim_rtprio) |
4066 | return -EPERM; | |
4067 | ||
d1ccc66d | 4068 | /* Can't increase priority: */ |
d50dde5a DF |
4069 | if (attr->sched_priority > p->rt_priority && |
4070 | attr->sched_priority > rlim_rtprio) | |
8dc3e909 ON |
4071 | return -EPERM; |
4072 | } | |
c02aa73b | 4073 | |
d44753b8 JL |
4074 | /* |
4075 | * Can't set/change SCHED_DEADLINE policy at all for now | |
4076 | * (safest behavior); in the future we would like to allow | |
4077 | * unprivileged DL tasks to increase their relative deadline | |
4078 | * or reduce their runtime (both ways reducing utilization) | |
4079 | */ | |
4080 | if (dl_policy(policy)) | |
4081 | return -EPERM; | |
4082 | ||
dd41f596 | 4083 | /* |
c02aa73b DH |
4084 | * Treat SCHED_IDLE as nice 20. Only allow a switch to |
4085 | * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. | |
dd41f596 | 4086 | */ |
20f9cd2a | 4087 | if (idle_policy(p->policy) && !idle_policy(policy)) { |
d0ea0268 | 4088 | if (!can_nice(p, task_nice(p))) |
c02aa73b DH |
4089 | return -EPERM; |
4090 | } | |
5fe1d75f | 4091 | |
d1ccc66d | 4092 | /* Can't change other user's priorities: */ |
c69e8d9c | 4093 | if (!check_same_owner(p)) |
37e4ab3f | 4094 | return -EPERM; |
ca94c442 | 4095 | |
d1ccc66d | 4096 | /* Normal users shall not reset the sched_reset_on_fork flag: */ |
ca94c442 LP |
4097 | if (p->sched_reset_on_fork && !reset_on_fork) |
4098 | return -EPERM; | |
37e4ab3f | 4099 | } |
1da177e4 | 4100 | |
725aad24 | 4101 | if (user) { |
b0ae1981 | 4102 | retval = security_task_setscheduler(p); |
725aad24 JF |
4103 | if (retval) |
4104 | return retval; | |
4105 | } | |
4106 | ||
b29739f9 | 4107 | /* |
d1ccc66d | 4108 | * Make sure no PI-waiters arrive (or leave) while we are |
b29739f9 | 4109 | * changing the priority of the task: |
0122ec5b | 4110 | * |
25985edc | 4111 | * To be able to change p->policy safely, the appropriate |
1da177e4 LT |
4112 | * runqueue lock must be held. |
4113 | */ | |
eb580751 | 4114 | rq = task_rq_lock(p, &rf); |
80f5c1b8 | 4115 | update_rq_clock(rq); |
dc61b1d6 | 4116 | |
34f971f6 | 4117 | /* |
d1ccc66d | 4118 | * Changing the policy of the stop threads its a very bad idea: |
34f971f6 PZ |
4119 | */ |
4120 | if (p == rq->stop) { | |
eb580751 | 4121 | task_rq_unlock(rq, p, &rf); |
34f971f6 PZ |
4122 | return -EINVAL; |
4123 | } | |
4124 | ||
a51e9198 | 4125 | /* |
d6b1e911 TG |
4126 | * If not changing anything there's no need to proceed further, |
4127 | * but store a possible modification of reset_on_fork. | |
a51e9198 | 4128 | */ |
d50dde5a | 4129 | if (unlikely(policy == p->policy)) { |
d0ea0268 | 4130 | if (fair_policy(policy) && attr->sched_nice != task_nice(p)) |
d50dde5a DF |
4131 | goto change; |
4132 | if (rt_policy(policy) && attr->sched_priority != p->rt_priority) | |
4133 | goto change; | |
75381608 | 4134 | if (dl_policy(policy) && dl_param_changed(p, attr)) |
aab03e05 | 4135 | goto change; |
d50dde5a | 4136 | |
d6b1e911 | 4137 | p->sched_reset_on_fork = reset_on_fork; |
eb580751 | 4138 | task_rq_unlock(rq, p, &rf); |
a51e9198 DF |
4139 | return 0; |
4140 | } | |
d50dde5a | 4141 | change: |
a51e9198 | 4142 | |
dc61b1d6 | 4143 | if (user) { |
332ac17e | 4144 | #ifdef CONFIG_RT_GROUP_SCHED |
dc61b1d6 PZ |
4145 | /* |
4146 | * Do not allow realtime tasks into groups that have no runtime | |
4147 | * assigned. | |
4148 | */ | |
4149 | if (rt_bandwidth_enabled() && rt_policy(policy) && | |
f4493771 MG |
4150 | task_group(p)->rt_bandwidth.rt_runtime == 0 && |
4151 | !task_group_is_autogroup(task_group(p))) { | |
eb580751 | 4152 | task_rq_unlock(rq, p, &rf); |
dc61b1d6 PZ |
4153 | return -EPERM; |
4154 | } | |
dc61b1d6 | 4155 | #endif |
332ac17e DF |
4156 | #ifdef CONFIG_SMP |
4157 | if (dl_bandwidth_enabled() && dl_policy(policy)) { | |
4158 | cpumask_t *span = rq->rd->span; | |
332ac17e DF |
4159 | |
4160 | /* | |
4161 | * Don't allow tasks with an affinity mask smaller than | |
4162 | * the entire root_domain to become SCHED_DEADLINE. We | |
4163 | * will also fail if there's no bandwidth available. | |
4164 | */ | |
e4099a5e PZ |
4165 | if (!cpumask_subset(span, &p->cpus_allowed) || |
4166 | rq->rd->dl_bw.bw == 0) { | |
eb580751 | 4167 | task_rq_unlock(rq, p, &rf); |
332ac17e DF |
4168 | return -EPERM; |
4169 | } | |
4170 | } | |
4171 | #endif | |
4172 | } | |
dc61b1d6 | 4173 | |
d1ccc66d | 4174 | /* Re-check policy now with rq lock held: */ |
1da177e4 LT |
4175 | if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { |
4176 | policy = oldpolicy = -1; | |
eb580751 | 4177 | task_rq_unlock(rq, p, &rf); |
1da177e4 LT |
4178 | goto recheck; |
4179 | } | |
332ac17e DF |
4180 | |
4181 | /* | |
4182 | * If setscheduling to SCHED_DEADLINE (or changing the parameters | |
4183 | * of a SCHED_DEADLINE task) we need to check if enough bandwidth | |
4184 | * is available. | |
4185 | */ | |
06a76fe0 | 4186 | if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) { |
eb580751 | 4187 | task_rq_unlock(rq, p, &rf); |
332ac17e DF |
4188 | return -EBUSY; |
4189 | } | |
4190 | ||
c365c292 TG |
4191 | p->sched_reset_on_fork = reset_on_fork; |
4192 | oldprio = p->prio; | |
4193 | ||
dbc7f069 PZ |
4194 | if (pi) { |
4195 | /* | |
4196 | * Take priority boosted tasks into account. If the new | |
4197 | * effective priority is unchanged, we just store the new | |
4198 | * normal parameters and do not touch the scheduler class and | |
4199 | * the runqueue. This will be done when the task deboost | |
4200 | * itself. | |
4201 | */ | |
acd58620 | 4202 | new_effective_prio = rt_effective_prio(p, newprio); |
ff77e468 PZ |
4203 | if (new_effective_prio == oldprio) |
4204 | queue_flags &= ~DEQUEUE_MOVE; | |
c365c292 TG |
4205 | } |
4206 | ||
da0c1e65 | 4207 | queued = task_on_rq_queued(p); |
051a1d1a | 4208 | running = task_current(rq, p); |
da0c1e65 | 4209 | if (queued) |
ff77e468 | 4210 | dequeue_task(rq, p, queue_flags); |
0e1f3483 | 4211 | if (running) |
f3cd1c4e | 4212 | put_prev_task(rq, p); |
f6b53205 | 4213 | |
83ab0aa0 | 4214 | prev_class = p->sched_class; |
dbc7f069 | 4215 | __setscheduler(rq, p, attr, pi); |
f6b53205 | 4216 | |
da0c1e65 | 4217 | if (queued) { |
81a44c54 TG |
4218 | /* |
4219 | * We enqueue to tail when the priority of a task is | |
4220 | * increased (user space view). | |
4221 | */ | |
ff77e468 PZ |
4222 | if (oldprio < p->prio) |
4223 | queue_flags |= ENQUEUE_HEAD; | |
1de64443 | 4224 | |
ff77e468 | 4225 | enqueue_task(rq, p, queue_flags); |
81a44c54 | 4226 | } |
a399d233 | 4227 | if (running) |
b2bf6c31 | 4228 | set_curr_task(rq, p); |
cb469845 | 4229 | |
da7a735e | 4230 | check_class_changed(rq, p, prev_class, oldprio); |
d1ccc66d IM |
4231 | |
4232 | /* Avoid rq from going away on us: */ | |
4233 | preempt_disable(); | |
eb580751 | 4234 | task_rq_unlock(rq, p, &rf); |
b29739f9 | 4235 | |
dbc7f069 PZ |
4236 | if (pi) |
4237 | rt_mutex_adjust_pi(p); | |
95e02ca9 | 4238 | |
d1ccc66d | 4239 | /* Run balance callbacks after we've adjusted the PI chain: */ |
4c9a4bc8 PZ |
4240 | balance_callback(rq); |
4241 | preempt_enable(); | |
95e02ca9 | 4242 | |
1da177e4 LT |
4243 | return 0; |
4244 | } | |
961ccddd | 4245 | |
7479f3c9 PZ |
4246 | static int _sched_setscheduler(struct task_struct *p, int policy, |
4247 | const struct sched_param *param, bool check) | |
4248 | { | |
4249 | struct sched_attr attr = { | |
4250 | .sched_policy = policy, | |
4251 | .sched_priority = param->sched_priority, | |
4252 | .sched_nice = PRIO_TO_NICE(p->static_prio), | |
4253 | }; | |
4254 | ||
c13db6b1 SR |
4255 | /* Fixup the legacy SCHED_RESET_ON_FORK hack. */ |
4256 | if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) { | |
7479f3c9 PZ |
4257 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; |
4258 | policy &= ~SCHED_RESET_ON_FORK; | |
4259 | attr.sched_policy = policy; | |
4260 | } | |
4261 | ||
dbc7f069 | 4262 | return __sched_setscheduler(p, &attr, check, true); |
7479f3c9 | 4263 | } |
961ccddd RR |
4264 | /** |
4265 | * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. | |
4266 | * @p: the task in question. | |
4267 | * @policy: new policy. | |
4268 | * @param: structure containing the new RT priority. | |
4269 | * | |
e69f6186 YB |
4270 | * Return: 0 on success. An error code otherwise. |
4271 | * | |
961ccddd RR |
4272 | * NOTE that the task may be already dead. |
4273 | */ | |
4274 | int sched_setscheduler(struct task_struct *p, int policy, | |
fe7de49f | 4275 | const struct sched_param *param) |
961ccddd | 4276 | { |
7479f3c9 | 4277 | return _sched_setscheduler(p, policy, param, true); |
961ccddd | 4278 | } |
1da177e4 LT |
4279 | EXPORT_SYMBOL_GPL(sched_setscheduler); |
4280 | ||
d50dde5a DF |
4281 | int sched_setattr(struct task_struct *p, const struct sched_attr *attr) |
4282 | { | |
dbc7f069 | 4283 | return __sched_setscheduler(p, attr, true, true); |
d50dde5a DF |
4284 | } |
4285 | EXPORT_SYMBOL_GPL(sched_setattr); | |
4286 | ||
961ccddd RR |
4287 | /** |
4288 | * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. | |
4289 | * @p: the task in question. | |
4290 | * @policy: new policy. | |
4291 | * @param: structure containing the new RT priority. | |
4292 | * | |
4293 | * Just like sched_setscheduler, only don't bother checking if the | |
4294 | * current context has permission. For example, this is needed in | |
4295 | * stop_machine(): we create temporary high priority worker threads, | |
4296 | * but our caller might not have that capability. | |
e69f6186 YB |
4297 | * |
4298 | * Return: 0 on success. An error code otherwise. | |
961ccddd RR |
4299 | */ |
4300 | int sched_setscheduler_nocheck(struct task_struct *p, int policy, | |
fe7de49f | 4301 | const struct sched_param *param) |
961ccddd | 4302 | { |
7479f3c9 | 4303 | return _sched_setscheduler(p, policy, param, false); |
961ccddd | 4304 | } |
84778472 | 4305 | EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck); |
961ccddd | 4306 | |
95cdf3b7 IM |
4307 | static int |
4308 | do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) | |
1da177e4 | 4309 | { |
1da177e4 LT |
4310 | struct sched_param lparam; |
4311 | struct task_struct *p; | |
36c8b586 | 4312 | int retval; |
1da177e4 LT |
4313 | |
4314 | if (!param || pid < 0) | |
4315 | return -EINVAL; | |
4316 | if (copy_from_user(&lparam, param, sizeof(struct sched_param))) | |
4317 | return -EFAULT; | |
5fe1d75f ON |
4318 | |
4319 | rcu_read_lock(); | |
4320 | retval = -ESRCH; | |
1da177e4 | 4321 | p = find_process_by_pid(pid); |
5fe1d75f ON |
4322 | if (p != NULL) |
4323 | retval = sched_setscheduler(p, policy, &lparam); | |
4324 | rcu_read_unlock(); | |
36c8b586 | 4325 | |
1da177e4 LT |
4326 | return retval; |
4327 | } | |
4328 | ||
d50dde5a DF |
4329 | /* |
4330 | * Mimics kernel/events/core.c perf_copy_attr(). | |
4331 | */ | |
d1ccc66d | 4332 | static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) |
d50dde5a DF |
4333 | { |
4334 | u32 size; | |
4335 | int ret; | |
4336 | ||
4337 | if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) | |
4338 | return -EFAULT; | |
4339 | ||
d1ccc66d | 4340 | /* Zero the full structure, so that a short copy will be nice: */ |
d50dde5a DF |
4341 | memset(attr, 0, sizeof(*attr)); |
4342 | ||
4343 | ret = get_user(size, &uattr->size); | |
4344 | if (ret) | |
4345 | return ret; | |
4346 | ||
d1ccc66d IM |
4347 | /* Bail out on silly large: */ |
4348 | if (size > PAGE_SIZE) | |
d50dde5a DF |
4349 | goto err_size; |
4350 | ||
d1ccc66d IM |
4351 | /* ABI compatibility quirk: */ |
4352 | if (!size) | |
d50dde5a DF |
4353 | size = SCHED_ATTR_SIZE_VER0; |
4354 | ||
4355 | if (size < SCHED_ATTR_SIZE_VER0) | |
4356 | goto err_size; | |
4357 | ||
4358 | /* | |
4359 | * If we're handed a bigger struct than we know of, | |
4360 | * ensure all the unknown bits are 0 - i.e. new | |
4361 | * user-space does not rely on any kernel feature | |
4362 | * extensions we dont know about yet. | |
4363 | */ | |
4364 | if (size > sizeof(*attr)) { | |
4365 | unsigned char __user *addr; | |
4366 | unsigned char __user *end; | |
4367 | unsigned char val; | |
4368 | ||
4369 | addr = (void __user *)uattr + sizeof(*attr); | |
4370 | end = (void __user *)uattr + size; | |
4371 | ||
4372 | for (; addr < end; addr++) { | |
4373 | ret = get_user(val, addr); | |
4374 | if (ret) | |
4375 | return ret; | |
4376 | if (val) | |
4377 | goto err_size; | |
4378 | } | |
4379 | size = sizeof(*attr); | |
4380 | } | |
4381 | ||
4382 | ret = copy_from_user(attr, uattr, size); | |
4383 | if (ret) | |
4384 | return -EFAULT; | |
4385 | ||
4386 | /* | |
d1ccc66d | 4387 | * XXX: Do we want to be lenient like existing syscalls; or do we want |
d50dde5a DF |
4388 | * to be strict and return an error on out-of-bounds values? |
4389 | */ | |
75e45d51 | 4390 | attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE); |
d50dde5a | 4391 | |
e78c7bca | 4392 | return 0; |
d50dde5a DF |
4393 | |
4394 | err_size: | |
4395 | put_user(sizeof(*attr), &uattr->size); | |
e78c7bca | 4396 | return -E2BIG; |
d50dde5a DF |
4397 | } |
4398 | ||
1da177e4 LT |
4399 | /** |
4400 | * sys_sched_setscheduler - set/change the scheduler policy and RT priority | |
4401 | * @pid: the pid in question. | |
4402 | * @policy: new policy. | |
4403 | * @param: structure containing the new RT priority. | |
e69f6186 YB |
4404 | * |
4405 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4406 | */ |
d1ccc66d | 4407 | SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param) |
1da177e4 | 4408 | { |
c21761f1 JB |
4409 | if (policy < 0) |
4410 | return -EINVAL; | |
4411 | ||
1da177e4 LT |
4412 | return do_sched_setscheduler(pid, policy, param); |
4413 | } | |
4414 | ||
4415 | /** | |
4416 | * sys_sched_setparam - set/change the RT priority of a thread | |
4417 | * @pid: the pid in question. | |
4418 | * @param: structure containing the new RT priority. | |
e69f6186 YB |
4419 | * |
4420 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4421 | */ |
5add95d4 | 4422 | SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) |
1da177e4 | 4423 | { |
c13db6b1 | 4424 | return do_sched_setscheduler(pid, SETPARAM_POLICY, param); |
1da177e4 LT |
4425 | } |
4426 | ||
d50dde5a DF |
4427 | /** |
4428 | * sys_sched_setattr - same as above, but with extended sched_attr | |
4429 | * @pid: the pid in question. | |
5778fccf | 4430 | * @uattr: structure containing the extended parameters. |
db66d756 | 4431 | * @flags: for future extension. |
d50dde5a | 4432 | */ |
6d35ab48 PZ |
4433 | SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr, |
4434 | unsigned int, flags) | |
d50dde5a DF |
4435 | { |
4436 | struct sched_attr attr; | |
4437 | struct task_struct *p; | |
4438 | int retval; | |
4439 | ||
6d35ab48 | 4440 | if (!uattr || pid < 0 || flags) |
d50dde5a DF |
4441 | return -EINVAL; |
4442 | ||
143cf23d MK |
4443 | retval = sched_copy_attr(uattr, &attr); |
4444 | if (retval) | |
4445 | return retval; | |
d50dde5a | 4446 | |
b14ed2c2 | 4447 | if ((int)attr.sched_policy < 0) |
dbdb2275 | 4448 | return -EINVAL; |
d50dde5a DF |
4449 | |
4450 | rcu_read_lock(); | |
4451 | retval = -ESRCH; | |
4452 | p = find_process_by_pid(pid); | |
4453 | if (p != NULL) | |
4454 | retval = sched_setattr(p, &attr); | |
4455 | rcu_read_unlock(); | |
4456 | ||
4457 | return retval; | |
4458 | } | |
4459 | ||
1da177e4 LT |
4460 | /** |
4461 | * sys_sched_getscheduler - get the policy (scheduling class) of a thread | |
4462 | * @pid: the pid in question. | |
e69f6186 YB |
4463 | * |
4464 | * Return: On success, the policy of the thread. Otherwise, a negative error | |
4465 | * code. | |
1da177e4 | 4466 | */ |
5add95d4 | 4467 | SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) |
1da177e4 | 4468 | { |
36c8b586 | 4469 | struct task_struct *p; |
3a5c359a | 4470 | int retval; |
1da177e4 LT |
4471 | |
4472 | if (pid < 0) | |
3a5c359a | 4473 | return -EINVAL; |
1da177e4 LT |
4474 | |
4475 | retval = -ESRCH; | |
5fe85be0 | 4476 | rcu_read_lock(); |
1da177e4 LT |
4477 | p = find_process_by_pid(pid); |
4478 | if (p) { | |
4479 | retval = security_task_getscheduler(p); | |
4480 | if (!retval) | |
ca94c442 LP |
4481 | retval = p->policy |
4482 | | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); | |
1da177e4 | 4483 | } |
5fe85be0 | 4484 | rcu_read_unlock(); |
1da177e4 LT |
4485 | return retval; |
4486 | } | |
4487 | ||
4488 | /** | |
ca94c442 | 4489 | * sys_sched_getparam - get the RT priority of a thread |
1da177e4 LT |
4490 | * @pid: the pid in question. |
4491 | * @param: structure containing the RT priority. | |
e69f6186 YB |
4492 | * |
4493 | * Return: On success, 0 and the RT priority is in @param. Otherwise, an error | |
4494 | * code. | |
1da177e4 | 4495 | */ |
5add95d4 | 4496 | SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) |
1da177e4 | 4497 | { |
ce5f7f82 | 4498 | struct sched_param lp = { .sched_priority = 0 }; |
36c8b586 | 4499 | struct task_struct *p; |
3a5c359a | 4500 | int retval; |
1da177e4 LT |
4501 | |
4502 | if (!param || pid < 0) | |
3a5c359a | 4503 | return -EINVAL; |
1da177e4 | 4504 | |
5fe85be0 | 4505 | rcu_read_lock(); |
1da177e4 LT |
4506 | p = find_process_by_pid(pid); |
4507 | retval = -ESRCH; | |
4508 | if (!p) | |
4509 | goto out_unlock; | |
4510 | ||
4511 | retval = security_task_getscheduler(p); | |
4512 | if (retval) | |
4513 | goto out_unlock; | |
4514 | ||
ce5f7f82 PZ |
4515 | if (task_has_rt_policy(p)) |
4516 | lp.sched_priority = p->rt_priority; | |
5fe85be0 | 4517 | rcu_read_unlock(); |
1da177e4 LT |
4518 | |
4519 | /* | |
4520 | * This one might sleep, we cannot do it with a spinlock held ... | |
4521 | */ | |
4522 | retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; | |
4523 | ||
1da177e4 LT |
4524 | return retval; |
4525 | ||
4526 | out_unlock: | |
5fe85be0 | 4527 | rcu_read_unlock(); |
1da177e4 LT |
4528 | return retval; |
4529 | } | |
4530 | ||
d50dde5a DF |
4531 | static int sched_read_attr(struct sched_attr __user *uattr, |
4532 | struct sched_attr *attr, | |
4533 | unsigned int usize) | |
4534 | { | |
4535 | int ret; | |
4536 | ||
4537 | if (!access_ok(VERIFY_WRITE, uattr, usize)) | |
4538 | return -EFAULT; | |
4539 | ||
4540 | /* | |
4541 | * If we're handed a smaller struct than we know of, | |
4542 | * ensure all the unknown bits are 0 - i.e. old | |
4543 | * user-space does not get uncomplete information. | |
4544 | */ | |
4545 | if (usize < sizeof(*attr)) { | |
4546 | unsigned char *addr; | |
4547 | unsigned char *end; | |
4548 | ||
4549 | addr = (void *)attr + usize; | |
4550 | end = (void *)attr + sizeof(*attr); | |
4551 | ||
4552 | for (; addr < end; addr++) { | |
4553 | if (*addr) | |
22400674 | 4554 | return -EFBIG; |
d50dde5a DF |
4555 | } |
4556 | ||
4557 | attr->size = usize; | |
4558 | } | |
4559 | ||
4efbc454 | 4560 | ret = copy_to_user(uattr, attr, attr->size); |
d50dde5a DF |
4561 | if (ret) |
4562 | return -EFAULT; | |
4563 | ||
22400674 | 4564 | return 0; |
d50dde5a DF |
4565 | } |
4566 | ||
4567 | /** | |
aab03e05 | 4568 | * sys_sched_getattr - similar to sched_getparam, but with sched_attr |
d50dde5a | 4569 | * @pid: the pid in question. |
5778fccf | 4570 | * @uattr: structure containing the extended parameters. |
d50dde5a | 4571 | * @size: sizeof(attr) for fwd/bwd comp. |
db66d756 | 4572 | * @flags: for future extension. |
d50dde5a | 4573 | */ |
6d35ab48 PZ |
4574 | SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, |
4575 | unsigned int, size, unsigned int, flags) | |
d50dde5a DF |
4576 | { |
4577 | struct sched_attr attr = { | |
4578 | .size = sizeof(struct sched_attr), | |
4579 | }; | |
4580 | struct task_struct *p; | |
4581 | int retval; | |
4582 | ||
4583 | if (!uattr || pid < 0 || size > PAGE_SIZE || | |
6d35ab48 | 4584 | size < SCHED_ATTR_SIZE_VER0 || flags) |
d50dde5a DF |
4585 | return -EINVAL; |
4586 | ||
4587 | rcu_read_lock(); | |
4588 | p = find_process_by_pid(pid); | |
4589 | retval = -ESRCH; | |
4590 | if (!p) | |
4591 | goto out_unlock; | |
4592 | ||
4593 | retval = security_task_getscheduler(p); | |
4594 | if (retval) | |
4595 | goto out_unlock; | |
4596 | ||
4597 | attr.sched_policy = p->policy; | |
7479f3c9 PZ |
4598 | if (p->sched_reset_on_fork) |
4599 | attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK; | |
aab03e05 DF |
4600 | if (task_has_dl_policy(p)) |
4601 | __getparam_dl(p, &attr); | |
4602 | else if (task_has_rt_policy(p)) | |
d50dde5a DF |
4603 | attr.sched_priority = p->rt_priority; |
4604 | else | |
d0ea0268 | 4605 | attr.sched_nice = task_nice(p); |
d50dde5a DF |
4606 | |
4607 | rcu_read_unlock(); | |
4608 | ||
4609 | retval = sched_read_attr(uattr, &attr, size); | |
4610 | return retval; | |
4611 | ||
4612 | out_unlock: | |
4613 | rcu_read_unlock(); | |
4614 | return retval; | |
4615 | } | |
4616 | ||
96f874e2 | 4617 | long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) |
1da177e4 | 4618 | { |
5a16f3d3 | 4619 | cpumask_var_t cpus_allowed, new_mask; |
36c8b586 IM |
4620 | struct task_struct *p; |
4621 | int retval; | |
1da177e4 | 4622 | |
23f5d142 | 4623 | rcu_read_lock(); |
1da177e4 LT |
4624 | |
4625 | p = find_process_by_pid(pid); | |
4626 | if (!p) { | |
23f5d142 | 4627 | rcu_read_unlock(); |
1da177e4 LT |
4628 | return -ESRCH; |
4629 | } | |
4630 | ||
23f5d142 | 4631 | /* Prevent p going away */ |
1da177e4 | 4632 | get_task_struct(p); |
23f5d142 | 4633 | rcu_read_unlock(); |
1da177e4 | 4634 | |
14a40ffc TH |
4635 | if (p->flags & PF_NO_SETAFFINITY) { |
4636 | retval = -EINVAL; | |
4637 | goto out_put_task; | |
4638 | } | |
5a16f3d3 RR |
4639 | if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { |
4640 | retval = -ENOMEM; | |
4641 | goto out_put_task; | |
4642 | } | |
4643 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { | |
4644 | retval = -ENOMEM; | |
4645 | goto out_free_cpus_allowed; | |
4646 | } | |
1da177e4 | 4647 | retval = -EPERM; |
4c44aaaf EB |
4648 | if (!check_same_owner(p)) { |
4649 | rcu_read_lock(); | |
4650 | if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { | |
4651 | rcu_read_unlock(); | |
16303ab2 | 4652 | goto out_free_new_mask; |
4c44aaaf EB |
4653 | } |
4654 | rcu_read_unlock(); | |
4655 | } | |
1da177e4 | 4656 | |
b0ae1981 | 4657 | retval = security_task_setscheduler(p); |
e7834f8f | 4658 | if (retval) |
16303ab2 | 4659 | goto out_free_new_mask; |
e7834f8f | 4660 | |
e4099a5e PZ |
4661 | |
4662 | cpuset_cpus_allowed(p, cpus_allowed); | |
4663 | cpumask_and(new_mask, in_mask, cpus_allowed); | |
4664 | ||
332ac17e DF |
4665 | /* |
4666 | * Since bandwidth control happens on root_domain basis, | |
4667 | * if admission test is enabled, we only admit -deadline | |
4668 | * tasks allowed to run on all the CPUs in the task's | |
4669 | * root_domain. | |
4670 | */ | |
4671 | #ifdef CONFIG_SMP | |
f1e3a093 KT |
4672 | if (task_has_dl_policy(p) && dl_bandwidth_enabled()) { |
4673 | rcu_read_lock(); | |
4674 | if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) { | |
332ac17e | 4675 | retval = -EBUSY; |
f1e3a093 | 4676 | rcu_read_unlock(); |
16303ab2 | 4677 | goto out_free_new_mask; |
332ac17e | 4678 | } |
f1e3a093 | 4679 | rcu_read_unlock(); |
332ac17e DF |
4680 | } |
4681 | #endif | |
49246274 | 4682 | again: |
25834c73 | 4683 | retval = __set_cpus_allowed_ptr(p, new_mask, true); |
1da177e4 | 4684 | |
8707d8b8 | 4685 | if (!retval) { |
5a16f3d3 RR |
4686 | cpuset_cpus_allowed(p, cpus_allowed); |
4687 | if (!cpumask_subset(new_mask, cpus_allowed)) { | |
8707d8b8 PM |
4688 | /* |
4689 | * We must have raced with a concurrent cpuset | |
4690 | * update. Just reset the cpus_allowed to the | |
4691 | * cpuset's cpus_allowed | |
4692 | */ | |
5a16f3d3 | 4693 | cpumask_copy(new_mask, cpus_allowed); |
8707d8b8 PM |
4694 | goto again; |
4695 | } | |
4696 | } | |
16303ab2 | 4697 | out_free_new_mask: |
5a16f3d3 RR |
4698 | free_cpumask_var(new_mask); |
4699 | out_free_cpus_allowed: | |
4700 | free_cpumask_var(cpus_allowed); | |
4701 | out_put_task: | |
1da177e4 | 4702 | put_task_struct(p); |
1da177e4 LT |
4703 | return retval; |
4704 | } | |
4705 | ||
4706 | static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, | |
96f874e2 | 4707 | struct cpumask *new_mask) |
1da177e4 | 4708 | { |
96f874e2 RR |
4709 | if (len < cpumask_size()) |
4710 | cpumask_clear(new_mask); | |
4711 | else if (len > cpumask_size()) | |
4712 | len = cpumask_size(); | |
4713 | ||
1da177e4 LT |
4714 | return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; |
4715 | } | |
4716 | ||
4717 | /** | |
d1ccc66d | 4718 | * sys_sched_setaffinity - set the CPU affinity of a process |
1da177e4 LT |
4719 | * @pid: pid of the process |
4720 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
d1ccc66d | 4721 | * @user_mask_ptr: user-space pointer to the new CPU mask |
e69f6186 YB |
4722 | * |
4723 | * Return: 0 on success. An error code otherwise. | |
1da177e4 | 4724 | */ |
5add95d4 HC |
4725 | SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, |
4726 | unsigned long __user *, user_mask_ptr) | |
1da177e4 | 4727 | { |
5a16f3d3 | 4728 | cpumask_var_t new_mask; |
1da177e4 LT |
4729 | int retval; |
4730 | ||
5a16f3d3 RR |
4731 | if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) |
4732 | return -ENOMEM; | |
1da177e4 | 4733 | |
5a16f3d3 RR |
4734 | retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); |
4735 | if (retval == 0) | |
4736 | retval = sched_setaffinity(pid, new_mask); | |
4737 | free_cpumask_var(new_mask); | |
4738 | return retval; | |
1da177e4 LT |
4739 | } |
4740 | ||
96f874e2 | 4741 | long sched_getaffinity(pid_t pid, struct cpumask *mask) |
1da177e4 | 4742 | { |
36c8b586 | 4743 | struct task_struct *p; |
31605683 | 4744 | unsigned long flags; |
1da177e4 | 4745 | int retval; |
1da177e4 | 4746 | |
23f5d142 | 4747 | rcu_read_lock(); |
1da177e4 LT |
4748 | |
4749 | retval = -ESRCH; | |
4750 | p = find_process_by_pid(pid); | |
4751 | if (!p) | |
4752 | goto out_unlock; | |
4753 | ||
e7834f8f DQ |
4754 | retval = security_task_getscheduler(p); |
4755 | if (retval) | |
4756 | goto out_unlock; | |
4757 | ||
013fdb80 | 4758 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
6acce3ef | 4759 | cpumask_and(mask, &p->cpus_allowed, cpu_active_mask); |
013fdb80 | 4760 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
1da177e4 LT |
4761 | |
4762 | out_unlock: | |
23f5d142 | 4763 | rcu_read_unlock(); |
1da177e4 | 4764 | |
9531b62f | 4765 | return retval; |
1da177e4 LT |
4766 | } |
4767 | ||
4768 | /** | |
d1ccc66d | 4769 | * sys_sched_getaffinity - get the CPU affinity of a process |
1da177e4 LT |
4770 | * @pid: pid of the process |
4771 | * @len: length in bytes of the bitmask pointed to by user_mask_ptr | |
d1ccc66d | 4772 | * @user_mask_ptr: user-space pointer to hold the current CPU mask |
e69f6186 | 4773 | * |
599b4840 ZW |
4774 | * Return: size of CPU mask copied to user_mask_ptr on success. An |
4775 | * error code otherwise. | |
1da177e4 | 4776 | */ |
5add95d4 HC |
4777 | SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, |
4778 | unsigned long __user *, user_mask_ptr) | |
1da177e4 LT |
4779 | { |
4780 | int ret; | |
f17c8607 | 4781 | cpumask_var_t mask; |
1da177e4 | 4782 | |
84fba5ec | 4783 | if ((len * BITS_PER_BYTE) < nr_cpu_ids) |
cd3d8031 KM |
4784 | return -EINVAL; |
4785 | if (len & (sizeof(unsigned long)-1)) | |
1da177e4 LT |
4786 | return -EINVAL; |
4787 | ||
f17c8607 RR |
4788 | if (!alloc_cpumask_var(&mask, GFP_KERNEL)) |
4789 | return -ENOMEM; | |
1da177e4 | 4790 | |
f17c8607 RR |
4791 | ret = sched_getaffinity(pid, mask); |
4792 | if (ret == 0) { | |
8bc037fb | 4793 | size_t retlen = min_t(size_t, len, cpumask_size()); |
cd3d8031 KM |
4794 | |
4795 | if (copy_to_user(user_mask_ptr, mask, retlen)) | |
f17c8607 RR |
4796 | ret = -EFAULT; |
4797 | else | |
cd3d8031 | 4798 | ret = retlen; |
f17c8607 RR |
4799 | } |
4800 | free_cpumask_var(mask); | |
1da177e4 | 4801 | |
f17c8607 | 4802 | return ret; |
1da177e4 LT |
4803 | } |
4804 | ||
4805 | /** | |
4806 | * sys_sched_yield - yield the current processor to other threads. | |
4807 | * | |
dd41f596 IM |
4808 | * This function yields the current CPU to other tasks. If there are no |
4809 | * other threads running on this CPU then this function will return. | |
e69f6186 YB |
4810 | * |
4811 | * Return: 0. | |
1da177e4 | 4812 | */ |
5add95d4 | 4813 | SYSCALL_DEFINE0(sched_yield) |
1da177e4 | 4814 | { |
8a8c69c3 PZ |
4815 | struct rq_flags rf; |
4816 | struct rq *rq; | |
4817 | ||
4818 | local_irq_disable(); | |
4819 | rq = this_rq(); | |
4820 | rq_lock(rq, &rf); | |
1da177e4 | 4821 | |
ae92882e | 4822 | schedstat_inc(rq->yld_count); |
4530d7ab | 4823 | current->sched_class->yield_task(rq); |
1da177e4 LT |
4824 | |
4825 | /* | |
4826 | * Since we are going to call schedule() anyway, there's | |
4827 | * no need to preempt or enable interrupts: | |
4828 | */ | |
8a8c69c3 PZ |
4829 | preempt_disable(); |
4830 | rq_unlock(rq, &rf); | |
ba74c144 | 4831 | sched_preempt_enable_no_resched(); |
1da177e4 LT |
4832 | |
4833 | schedule(); | |
4834 | ||
4835 | return 0; | |
4836 | } | |
4837 | ||
35a773a0 | 4838 | #ifndef CONFIG_PREEMPT |
02b67cc3 | 4839 | int __sched _cond_resched(void) |
1da177e4 | 4840 | { |
fe32d3cd | 4841 | if (should_resched(0)) { |
a18b5d01 | 4842 | preempt_schedule_common(); |
1da177e4 LT |
4843 | return 1; |
4844 | } | |
4845 | return 0; | |
4846 | } | |
02b67cc3 | 4847 | EXPORT_SYMBOL(_cond_resched); |
35a773a0 | 4848 | #endif |
1da177e4 LT |
4849 | |
4850 | /* | |
613afbf8 | 4851 | * __cond_resched_lock() - if a reschedule is pending, drop the given lock, |
1da177e4 LT |
4852 | * call schedule, and on return reacquire the lock. |
4853 | * | |
41a2d6cf | 4854 | * This works OK both with and without CONFIG_PREEMPT. We do strange low-level |
1da177e4 LT |
4855 | * operations here to prevent schedule() from being called twice (once via |
4856 | * spin_unlock(), once by hand). | |
4857 | */ | |
613afbf8 | 4858 | int __cond_resched_lock(spinlock_t *lock) |
1da177e4 | 4859 | { |
fe32d3cd | 4860 | int resched = should_resched(PREEMPT_LOCK_OFFSET); |
6df3cecb JK |
4861 | int ret = 0; |
4862 | ||
f607c668 PZ |
4863 | lockdep_assert_held(lock); |
4864 | ||
4a81e832 | 4865 | if (spin_needbreak(lock) || resched) { |
1da177e4 | 4866 | spin_unlock(lock); |
d86ee480 | 4867 | if (resched) |
a18b5d01 | 4868 | preempt_schedule_common(); |
95c354fe NP |
4869 | else |
4870 | cpu_relax(); | |
6df3cecb | 4871 | ret = 1; |
1da177e4 | 4872 | spin_lock(lock); |
1da177e4 | 4873 | } |
6df3cecb | 4874 | return ret; |
1da177e4 | 4875 | } |
613afbf8 | 4876 | EXPORT_SYMBOL(__cond_resched_lock); |
1da177e4 | 4877 | |
613afbf8 | 4878 | int __sched __cond_resched_softirq(void) |
1da177e4 LT |
4879 | { |
4880 | BUG_ON(!in_softirq()); | |
4881 | ||
fe32d3cd | 4882 | if (should_resched(SOFTIRQ_DISABLE_OFFSET)) { |
98d82567 | 4883 | local_bh_enable(); |
a18b5d01 | 4884 | preempt_schedule_common(); |
1da177e4 LT |
4885 | local_bh_disable(); |
4886 | return 1; | |
4887 | } | |
4888 | return 0; | |
4889 | } | |
613afbf8 | 4890 | EXPORT_SYMBOL(__cond_resched_softirq); |
1da177e4 | 4891 | |
1da177e4 LT |
4892 | /** |
4893 | * yield - yield the current processor to other threads. | |
4894 | * | |
8e3fabfd PZ |
4895 | * Do not ever use this function, there's a 99% chance you're doing it wrong. |
4896 | * | |
4897 | * The scheduler is at all times free to pick the calling task as the most | |
4898 | * eligible task to run, if removing the yield() call from your code breaks | |
4899 | * it, its already broken. | |
4900 | * | |
4901 | * Typical broken usage is: | |
4902 | * | |
4903 | * while (!event) | |
d1ccc66d | 4904 | * yield(); |
8e3fabfd PZ |
4905 | * |
4906 | * where one assumes that yield() will let 'the other' process run that will | |
4907 | * make event true. If the current task is a SCHED_FIFO task that will never | |
4908 | * happen. Never use yield() as a progress guarantee!! | |
4909 | * | |
4910 | * If you want to use yield() to wait for something, use wait_event(). | |
4911 | * If you want to use yield() to be 'nice' for others, use cond_resched(). | |
4912 | * If you still want to use yield(), do not! | |
1da177e4 LT |
4913 | */ |
4914 | void __sched yield(void) | |
4915 | { | |
4916 | set_current_state(TASK_RUNNING); | |
4917 | sys_sched_yield(); | |
4918 | } | |
1da177e4 LT |
4919 | EXPORT_SYMBOL(yield); |
4920 | ||
d95f4122 MG |
4921 | /** |
4922 | * yield_to - yield the current processor to another thread in | |
4923 | * your thread group, or accelerate that thread toward the | |
4924 | * processor it's on. | |
16addf95 RD |
4925 | * @p: target task |
4926 | * @preempt: whether task preemption is allowed or not | |
d95f4122 MG |
4927 | * |
4928 | * It's the caller's job to ensure that the target task struct | |
4929 | * can't go away on us before we can do any checks. | |
4930 | * | |
e69f6186 | 4931 | * Return: |
7b270f60 PZ |
4932 | * true (>0) if we indeed boosted the target task. |
4933 | * false (0) if we failed to boost the target. | |
4934 | * -ESRCH if there's no task to yield to. | |
d95f4122 | 4935 | */ |
fa93384f | 4936 | int __sched yield_to(struct task_struct *p, bool preempt) |
d95f4122 MG |
4937 | { |
4938 | struct task_struct *curr = current; | |
4939 | struct rq *rq, *p_rq; | |
4940 | unsigned long flags; | |
c3c18640 | 4941 | int yielded = 0; |
d95f4122 MG |
4942 | |
4943 | local_irq_save(flags); | |
4944 | rq = this_rq(); | |
4945 | ||
4946 | again: | |
4947 | p_rq = task_rq(p); | |
7b270f60 PZ |
4948 | /* |
4949 | * If we're the only runnable task on the rq and target rq also | |
4950 | * has only one task, there's absolutely no point in yielding. | |
4951 | */ | |
4952 | if (rq->nr_running == 1 && p_rq->nr_running == 1) { | |
4953 | yielded = -ESRCH; | |
4954 | goto out_irq; | |
4955 | } | |
4956 | ||
d95f4122 | 4957 | double_rq_lock(rq, p_rq); |
39e24d8f | 4958 | if (task_rq(p) != p_rq) { |
d95f4122 MG |
4959 | double_rq_unlock(rq, p_rq); |
4960 | goto again; | |
4961 | } | |
4962 | ||
4963 | if (!curr->sched_class->yield_to_task) | |
7b270f60 | 4964 | goto out_unlock; |
d95f4122 MG |
4965 | |
4966 | if (curr->sched_class != p->sched_class) | |
7b270f60 | 4967 | goto out_unlock; |
d95f4122 MG |
4968 | |
4969 | if (task_running(p_rq, p) || p->state) | |
7b270f60 | 4970 | goto out_unlock; |
d95f4122 MG |
4971 | |
4972 | yielded = curr->sched_class->yield_to_task(rq, p, preempt); | |
6d1cafd8 | 4973 | if (yielded) { |
ae92882e | 4974 | schedstat_inc(rq->yld_count); |
6d1cafd8 VP |
4975 | /* |
4976 | * Make p's CPU reschedule; pick_next_entity takes care of | |
4977 | * fairness. | |
4978 | */ | |
4979 | if (preempt && rq != p_rq) | |
8875125e | 4980 | resched_curr(p_rq); |
6d1cafd8 | 4981 | } |
d95f4122 | 4982 | |
7b270f60 | 4983 | out_unlock: |
d95f4122 | 4984 | double_rq_unlock(rq, p_rq); |
7b270f60 | 4985 | out_irq: |
d95f4122 MG |
4986 | local_irq_restore(flags); |
4987 | ||
7b270f60 | 4988 | if (yielded > 0) |
d95f4122 MG |
4989 | schedule(); |
4990 | ||
4991 | return yielded; | |
4992 | } | |
4993 | EXPORT_SYMBOL_GPL(yield_to); | |
4994 | ||
10ab5643 TH |
4995 | int io_schedule_prepare(void) |
4996 | { | |
4997 | int old_iowait = current->in_iowait; | |
4998 | ||
4999 | current->in_iowait = 1; | |
5000 | blk_schedule_flush_plug(current); | |
5001 | ||
5002 | return old_iowait; | |
5003 | } | |
5004 | ||
5005 | void io_schedule_finish(int token) | |
5006 | { | |
5007 | current->in_iowait = token; | |
5008 | } | |
5009 | ||
1da177e4 | 5010 | /* |
41a2d6cf | 5011 | * This task is about to go to sleep on IO. Increment rq->nr_iowait so |
1da177e4 | 5012 | * that process accounting knows that this is a task in IO wait state. |
1da177e4 | 5013 | */ |
1da177e4 LT |
5014 | long __sched io_schedule_timeout(long timeout) |
5015 | { | |
10ab5643 | 5016 | int token; |
1da177e4 LT |
5017 | long ret; |
5018 | ||
10ab5643 | 5019 | token = io_schedule_prepare(); |
1da177e4 | 5020 | ret = schedule_timeout(timeout); |
10ab5643 | 5021 | io_schedule_finish(token); |
9cff8ade | 5022 | |
1da177e4 LT |
5023 | return ret; |
5024 | } | |
9cff8ade | 5025 | EXPORT_SYMBOL(io_schedule_timeout); |
1da177e4 | 5026 | |
10ab5643 TH |
5027 | void io_schedule(void) |
5028 | { | |
5029 | int token; | |
5030 | ||
5031 | token = io_schedule_prepare(); | |
5032 | schedule(); | |
5033 | io_schedule_finish(token); | |
5034 | } | |
5035 | EXPORT_SYMBOL(io_schedule); | |
5036 | ||
1da177e4 LT |
5037 | /** |
5038 | * sys_sched_get_priority_max - return maximum RT priority. | |
5039 | * @policy: scheduling class. | |
5040 | * | |
e69f6186 YB |
5041 | * Return: On success, this syscall returns the maximum |
5042 | * rt_priority that can be used by a given scheduling class. | |
5043 | * On failure, a negative error code is returned. | |
1da177e4 | 5044 | */ |
5add95d4 | 5045 | SYSCALL_DEFINE1(sched_get_priority_max, int, policy) |
1da177e4 LT |
5046 | { |
5047 | int ret = -EINVAL; | |
5048 | ||
5049 | switch (policy) { | |
5050 | case SCHED_FIFO: | |
5051 | case SCHED_RR: | |
5052 | ret = MAX_USER_RT_PRIO-1; | |
5053 | break; | |
aab03e05 | 5054 | case SCHED_DEADLINE: |
1da177e4 | 5055 | case SCHED_NORMAL: |
b0a9499c | 5056 | case SCHED_BATCH: |
dd41f596 | 5057 | case SCHED_IDLE: |
1da177e4 LT |
5058 | ret = 0; |
5059 | break; | |
5060 | } | |
5061 | return ret; | |
5062 | } | |
5063 | ||
5064 | /** | |
5065 | * sys_sched_get_priority_min - return minimum RT priority. | |
5066 | * @policy: scheduling class. | |
5067 | * | |
e69f6186 YB |
5068 | * Return: On success, this syscall returns the minimum |
5069 | * rt_priority that can be used by a given scheduling class. | |
5070 | * On failure, a negative error code is returned. | |
1da177e4 | 5071 | */ |
5add95d4 | 5072 | SYSCALL_DEFINE1(sched_get_priority_min, int, policy) |
1da177e4 LT |
5073 | { |
5074 | int ret = -EINVAL; | |
5075 | ||
5076 | switch (policy) { | |
5077 | case SCHED_FIFO: | |
5078 | case SCHED_RR: | |
5079 | ret = 1; | |
5080 | break; | |
aab03e05 | 5081 | case SCHED_DEADLINE: |
1da177e4 | 5082 | case SCHED_NORMAL: |
b0a9499c | 5083 | case SCHED_BATCH: |
dd41f596 | 5084 | case SCHED_IDLE: |
1da177e4 LT |
5085 | ret = 0; |
5086 | } | |
5087 | return ret; | |
5088 | } | |
5089 | ||
5090 | /** | |
5091 | * sys_sched_rr_get_interval - return the default timeslice of a process. | |
5092 | * @pid: pid of the process. | |
5093 | * @interval: userspace pointer to the timeslice value. | |
5094 | * | |
5095 | * this syscall writes the default timeslice value of a given process | |
5096 | * into the user-space timespec buffer. A value of '0' means infinity. | |
e69f6186 YB |
5097 | * |
5098 | * Return: On success, 0 and the timeslice is in @interval. Otherwise, | |
5099 | * an error code. | |
1da177e4 | 5100 | */ |
17da2bd9 | 5101 | SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, |
754fe8d2 | 5102 | struct timespec __user *, interval) |
1da177e4 | 5103 | { |
36c8b586 | 5104 | struct task_struct *p; |
a4ec24b4 | 5105 | unsigned int time_slice; |
eb580751 PZ |
5106 | struct rq_flags rf; |
5107 | struct timespec t; | |
dba091b9 | 5108 | struct rq *rq; |
3a5c359a | 5109 | int retval; |
1da177e4 LT |
5110 | |
5111 | if (pid < 0) | |
3a5c359a | 5112 | return -EINVAL; |
1da177e4 LT |
5113 | |
5114 | retval = -ESRCH; | |
1a551ae7 | 5115 | rcu_read_lock(); |
1da177e4 LT |
5116 | p = find_process_by_pid(pid); |
5117 | if (!p) | |
5118 | goto out_unlock; | |
5119 | ||
5120 | retval = security_task_getscheduler(p); | |
5121 | if (retval) | |
5122 | goto out_unlock; | |
5123 | ||
eb580751 | 5124 | rq = task_rq_lock(p, &rf); |
a57beec5 PZ |
5125 | time_slice = 0; |
5126 | if (p->sched_class->get_rr_interval) | |
5127 | time_slice = p->sched_class->get_rr_interval(rq, p); | |
eb580751 | 5128 | task_rq_unlock(rq, p, &rf); |
a4ec24b4 | 5129 | |
1a551ae7 | 5130 | rcu_read_unlock(); |
a4ec24b4 | 5131 | jiffies_to_timespec(time_slice, &t); |
1da177e4 | 5132 | retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; |
1da177e4 | 5133 | return retval; |
3a5c359a | 5134 | |
1da177e4 | 5135 | out_unlock: |
1a551ae7 | 5136 | rcu_read_unlock(); |
1da177e4 LT |
5137 | return retval; |
5138 | } | |
5139 | ||
82a1fcb9 | 5140 | void sched_show_task(struct task_struct *p) |
1da177e4 | 5141 | { |
1da177e4 | 5142 | unsigned long free = 0; |
4e79752c | 5143 | int ppid; |
c930b2c0 | 5144 | |
38200502 TH |
5145 | if (!try_get_task_stack(p)) |
5146 | return; | |
20435d84 XX |
5147 | |
5148 | printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p)); | |
5149 | ||
5150 | if (p->state == TASK_RUNNING) | |
3df0fc5b | 5151 | printk(KERN_CONT " running task "); |
1da177e4 | 5152 | #ifdef CONFIG_DEBUG_STACK_USAGE |
7c9f8861 | 5153 | free = stack_not_used(p); |
1da177e4 | 5154 | #endif |
a90e984c | 5155 | ppid = 0; |
4e79752c | 5156 | rcu_read_lock(); |
a90e984c ON |
5157 | if (pid_alive(p)) |
5158 | ppid = task_pid_nr(rcu_dereference(p->real_parent)); | |
4e79752c | 5159 | rcu_read_unlock(); |
3df0fc5b | 5160 | printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, |
4e79752c | 5161 | task_pid_nr(p), ppid, |
aa47b7e0 | 5162 | (unsigned long)task_thread_info(p)->flags); |
1da177e4 | 5163 | |
3d1cb205 | 5164 | print_worker_info(KERN_INFO, p); |
5fb5e6de | 5165 | show_stack(p, NULL); |
38200502 | 5166 | put_task_stack(p); |
1da177e4 LT |
5167 | } |
5168 | ||
5d68cc95 PZ |
5169 | static inline bool |
5170 | state_filter_match(unsigned long state_filter, struct task_struct *p) | |
5171 | { | |
5172 | /* no filter, everything matches */ | |
5173 | if (!state_filter) | |
5174 | return true; | |
5175 | ||
5176 | /* filter, but doesn't match */ | |
5177 | if (!(p->state & state_filter)) | |
5178 | return false; | |
5179 | ||
5180 | /* | |
5181 | * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows | |
5182 | * TASK_KILLABLE). | |
5183 | */ | |
5184 | if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE) | |
5185 | return false; | |
5186 | ||
5187 | return true; | |
5188 | } | |
5189 | ||
5190 | ||
e59e2ae2 | 5191 | void show_state_filter(unsigned long state_filter) |
1da177e4 | 5192 | { |
36c8b586 | 5193 | struct task_struct *g, *p; |
1da177e4 | 5194 | |
4bd77321 | 5195 | #if BITS_PER_LONG == 32 |
3df0fc5b PZ |
5196 | printk(KERN_INFO |
5197 | " task PC stack pid father\n"); | |
1da177e4 | 5198 | #else |
3df0fc5b PZ |
5199 | printk(KERN_INFO |
5200 | " task PC stack pid father\n"); | |
1da177e4 | 5201 | #endif |
510f5acc | 5202 | rcu_read_lock(); |
5d07f420 | 5203 | for_each_process_thread(g, p) { |
1da177e4 LT |
5204 | /* |
5205 | * reset the NMI-timeout, listing all files on a slow | |
25985edc | 5206 | * console might take a lot of time: |
57675cb9 AR |
5207 | * Also, reset softlockup watchdogs on all CPUs, because |
5208 | * another CPU might be blocked waiting for us to process | |
5209 | * an IPI. | |
1da177e4 LT |
5210 | */ |
5211 | touch_nmi_watchdog(); | |
57675cb9 | 5212 | touch_all_softlockup_watchdogs(); |
5d68cc95 | 5213 | if (state_filter_match(state_filter, p)) |
82a1fcb9 | 5214 | sched_show_task(p); |
5d07f420 | 5215 | } |
1da177e4 | 5216 | |
dd41f596 | 5217 | #ifdef CONFIG_SCHED_DEBUG |
fb90a6e9 RV |
5218 | if (!state_filter) |
5219 | sysrq_sched_debug_show(); | |
dd41f596 | 5220 | #endif |
510f5acc | 5221 | rcu_read_unlock(); |
e59e2ae2 IM |
5222 | /* |
5223 | * Only show locks if all tasks are dumped: | |
5224 | */ | |
93335a21 | 5225 | if (!state_filter) |
e59e2ae2 | 5226 | debug_show_all_locks(); |
1da177e4 LT |
5227 | } |
5228 | ||
f340c0d1 IM |
5229 | /** |
5230 | * init_idle - set up an idle thread for a given CPU | |
5231 | * @idle: task in question | |
d1ccc66d | 5232 | * @cpu: CPU the idle task belongs to |
f340c0d1 IM |
5233 | * |
5234 | * NOTE: this function does not set the idle thread's NEED_RESCHED | |
5235 | * flag, to make booting more robust. | |
5236 | */ | |
0db0628d | 5237 | void init_idle(struct task_struct *idle, int cpu) |
1da177e4 | 5238 | { |
70b97a7f | 5239 | struct rq *rq = cpu_rq(cpu); |
1da177e4 LT |
5240 | unsigned long flags; |
5241 | ||
25834c73 PZ |
5242 | raw_spin_lock_irqsave(&idle->pi_lock, flags); |
5243 | raw_spin_lock(&rq->lock); | |
5cbd54ef | 5244 | |
5e1576ed | 5245 | __sched_fork(0, idle); |
06b83b5f | 5246 | idle->state = TASK_RUNNING; |
dd41f596 | 5247 | idle->se.exec_start = sched_clock(); |
c1de45ca | 5248 | idle->flags |= PF_IDLE; |
dd41f596 | 5249 | |
e1b77c92 MR |
5250 | kasan_unpoison_task_stack(idle); |
5251 | ||
de9b8f5d PZ |
5252 | #ifdef CONFIG_SMP |
5253 | /* | |
5254 | * Its possible that init_idle() gets called multiple times on a task, | |
5255 | * in that case do_set_cpus_allowed() will not do the right thing. | |
5256 | * | |
5257 | * And since this is boot we can forgo the serialization. | |
5258 | */ | |
5259 | set_cpus_allowed_common(idle, cpumask_of(cpu)); | |
5260 | #endif | |
6506cf6c PZ |
5261 | /* |
5262 | * We're having a chicken and egg problem, even though we are | |
d1ccc66d | 5263 | * holding rq->lock, the CPU isn't yet set to this CPU so the |
6506cf6c PZ |
5264 | * lockdep check in task_group() will fail. |
5265 | * | |
5266 | * Similar case to sched_fork(). / Alternatively we could | |
5267 | * use task_rq_lock() here and obtain the other rq->lock. | |
5268 | * | |
5269 | * Silence PROVE_RCU | |
5270 | */ | |
5271 | rcu_read_lock(); | |
dd41f596 | 5272 | __set_task_cpu(idle, cpu); |
6506cf6c | 5273 | rcu_read_unlock(); |
1da177e4 | 5274 | |
1da177e4 | 5275 | rq->curr = rq->idle = idle; |
da0c1e65 | 5276 | idle->on_rq = TASK_ON_RQ_QUEUED; |
de9b8f5d | 5277 | #ifdef CONFIG_SMP |
3ca7a440 | 5278 | idle->on_cpu = 1; |
4866cde0 | 5279 | #endif |
25834c73 PZ |
5280 | raw_spin_unlock(&rq->lock); |
5281 | raw_spin_unlock_irqrestore(&idle->pi_lock, flags); | |
1da177e4 LT |
5282 | |
5283 | /* Set the preempt count _outside_ the spinlocks! */ | |
01028747 | 5284 | init_idle_preempt_count(idle, cpu); |
55cd5340 | 5285 | |
dd41f596 IM |
5286 | /* |
5287 | * The idle tasks have their own, simple scheduling class: | |
5288 | */ | |
5289 | idle->sched_class = &idle_sched_class; | |
868baf07 | 5290 | ftrace_graph_init_idle_task(idle, cpu); |
45eacc69 | 5291 | vtime_init_idle(idle, cpu); |
de9b8f5d | 5292 | #ifdef CONFIG_SMP |
f1c6f1a7 CE |
5293 | sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); |
5294 | #endif | |
19978ca6 IM |
5295 | } |
5296 | ||
e1d4eeec NP |
5297 | #ifdef CONFIG_SMP |
5298 | ||
f82f8042 JL |
5299 | int cpuset_cpumask_can_shrink(const struct cpumask *cur, |
5300 | const struct cpumask *trial) | |
5301 | { | |
06a76fe0 | 5302 | int ret = 1; |
f82f8042 | 5303 | |
bb2bc55a MG |
5304 | if (!cpumask_weight(cur)) |
5305 | return ret; | |
5306 | ||
06a76fe0 | 5307 | ret = dl_cpuset_cpumask_can_shrink(cur, trial); |
f82f8042 JL |
5308 | |
5309 | return ret; | |
5310 | } | |
5311 | ||
7f51412a JL |
5312 | int task_can_attach(struct task_struct *p, |
5313 | const struct cpumask *cs_cpus_allowed) | |
5314 | { | |
5315 | int ret = 0; | |
5316 | ||
5317 | /* | |
5318 | * Kthreads which disallow setaffinity shouldn't be moved | |
d1ccc66d | 5319 | * to a new cpuset; we don't want to change their CPU |
7f51412a JL |
5320 | * affinity and isolating such threads by their set of |
5321 | * allowed nodes is unnecessary. Thus, cpusets are not | |
5322 | * applicable for such threads. This prevents checking for | |
5323 | * success of set_cpus_allowed_ptr() on all attached tasks | |
5324 | * before cpus_allowed may be changed. | |
5325 | */ | |
5326 | if (p->flags & PF_NO_SETAFFINITY) { | |
5327 | ret = -EINVAL; | |
5328 | goto out; | |
5329 | } | |
5330 | ||
7f51412a | 5331 | if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, |
06a76fe0 NP |
5332 | cs_cpus_allowed)) |
5333 | ret = dl_task_can_attach(p, cs_cpus_allowed); | |
7f51412a | 5334 | |
7f51412a JL |
5335 | out: |
5336 | return ret; | |
5337 | } | |
5338 | ||
f2cb1360 | 5339 | bool sched_smp_initialized __read_mostly; |
e26fbffd | 5340 | |
e6628d5b MG |
5341 | #ifdef CONFIG_NUMA_BALANCING |
5342 | /* Migrate current task p to target_cpu */ | |
5343 | int migrate_task_to(struct task_struct *p, int target_cpu) | |
5344 | { | |
5345 | struct migration_arg arg = { p, target_cpu }; | |
5346 | int curr_cpu = task_cpu(p); | |
5347 | ||
5348 | if (curr_cpu == target_cpu) | |
5349 | return 0; | |
5350 | ||
0c98d344 | 5351 | if (!cpumask_test_cpu(target_cpu, &p->cpus_allowed)) |
e6628d5b MG |
5352 | return -EINVAL; |
5353 | ||
5354 | /* TODO: This is not properly updating schedstats */ | |
5355 | ||
286549dc | 5356 | trace_sched_move_numa(p, curr_cpu, target_cpu); |
e6628d5b MG |
5357 | return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); |
5358 | } | |
0ec8aa00 PZ |
5359 | |
5360 | /* | |
5361 | * Requeue a task on a given node and accurately track the number of NUMA | |
5362 | * tasks on the runqueues | |
5363 | */ | |
5364 | void sched_setnuma(struct task_struct *p, int nid) | |
5365 | { | |
da0c1e65 | 5366 | bool queued, running; |
eb580751 PZ |
5367 | struct rq_flags rf; |
5368 | struct rq *rq; | |
0ec8aa00 | 5369 | |
eb580751 | 5370 | rq = task_rq_lock(p, &rf); |
da0c1e65 | 5371 | queued = task_on_rq_queued(p); |
0ec8aa00 PZ |
5372 | running = task_current(rq, p); |
5373 | ||
da0c1e65 | 5374 | if (queued) |
1de64443 | 5375 | dequeue_task(rq, p, DEQUEUE_SAVE); |
0ec8aa00 | 5376 | if (running) |
f3cd1c4e | 5377 | put_prev_task(rq, p); |
0ec8aa00 PZ |
5378 | |
5379 | p->numa_preferred_nid = nid; | |
0ec8aa00 | 5380 | |
da0c1e65 | 5381 | if (queued) |
7134b3e9 | 5382 | enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); |
a399d233 | 5383 | if (running) |
b2bf6c31 | 5384 | set_curr_task(rq, p); |
eb580751 | 5385 | task_rq_unlock(rq, p, &rf); |
0ec8aa00 | 5386 | } |
5cc389bc | 5387 | #endif /* CONFIG_NUMA_BALANCING */ |
f7b4cddc | 5388 | |
1da177e4 | 5389 | #ifdef CONFIG_HOTPLUG_CPU |
054b9108 | 5390 | /* |
d1ccc66d | 5391 | * Ensure that the idle task is using init_mm right before its CPU goes |
48c5ccae | 5392 | * offline. |
054b9108 | 5393 | */ |
48c5ccae | 5394 | void idle_task_exit(void) |
1da177e4 | 5395 | { |
48c5ccae | 5396 | struct mm_struct *mm = current->active_mm; |
e76bd8d9 | 5397 | |
48c5ccae | 5398 | BUG_ON(cpu_online(smp_processor_id())); |
e76bd8d9 | 5399 | |
a53efe5f | 5400 | if (mm != &init_mm) { |
252d2a41 | 5401 | switch_mm(mm, &init_mm, current); |
a53efe5f MS |
5402 | finish_arch_post_lock_switch(); |
5403 | } | |
48c5ccae | 5404 | mmdrop(mm); |
1da177e4 LT |
5405 | } |
5406 | ||
5407 | /* | |
5d180232 PZ |
5408 | * Since this CPU is going 'away' for a while, fold any nr_active delta |
5409 | * we might have. Assumes we're called after migrate_tasks() so that the | |
d60585c5 TG |
5410 | * nr_active count is stable. We need to take the teardown thread which |
5411 | * is calling this into account, so we hand in adjust = 1 to the load | |
5412 | * calculation. | |
5d180232 PZ |
5413 | * |
5414 | * Also see the comment "Global load-average calculations". | |
1da177e4 | 5415 | */ |
5d180232 | 5416 | static void calc_load_migrate(struct rq *rq) |
1da177e4 | 5417 | { |
d60585c5 | 5418 | long delta = calc_load_fold_active(rq, 1); |
5d180232 PZ |
5419 | if (delta) |
5420 | atomic_long_add(delta, &calc_load_tasks); | |
1da177e4 LT |
5421 | } |
5422 | ||
3f1d2a31 PZ |
5423 | static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) |
5424 | { | |
5425 | } | |
5426 | ||
5427 | static const struct sched_class fake_sched_class = { | |
5428 | .put_prev_task = put_prev_task_fake, | |
5429 | }; | |
5430 | ||
5431 | static struct task_struct fake_task = { | |
5432 | /* | |
5433 | * Avoid pull_{rt,dl}_task() | |
5434 | */ | |
5435 | .prio = MAX_PRIO + 1, | |
5436 | .sched_class = &fake_sched_class, | |
5437 | }; | |
5438 | ||
48f24c4d | 5439 | /* |
48c5ccae PZ |
5440 | * Migrate all tasks from the rq, sleeping tasks will be migrated by |
5441 | * try_to_wake_up()->select_task_rq(). | |
5442 | * | |
5443 | * Called with rq->lock held even though we'er in stop_machine() and | |
5444 | * there's no concurrency possible, we hold the required locks anyway | |
5445 | * because of lock validation efforts. | |
1da177e4 | 5446 | */ |
8a8c69c3 | 5447 | static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf) |
1da177e4 | 5448 | { |
5e16bbc2 | 5449 | struct rq *rq = dead_rq; |
48c5ccae | 5450 | struct task_struct *next, *stop = rq->stop; |
8a8c69c3 | 5451 | struct rq_flags orf = *rf; |
48c5ccae | 5452 | int dest_cpu; |
1da177e4 LT |
5453 | |
5454 | /* | |
48c5ccae PZ |
5455 | * Fudge the rq selection such that the below task selection loop |
5456 | * doesn't get stuck on the currently eligible stop task. | |
5457 | * | |
5458 | * We're currently inside stop_machine() and the rq is either stuck | |
5459 | * in the stop_machine_cpu_stop() loop, or we're executing this code, | |
5460 | * either way we should never end up calling schedule() until we're | |
5461 | * done here. | |
1da177e4 | 5462 | */ |
48c5ccae | 5463 | rq->stop = NULL; |
48f24c4d | 5464 | |
77bd3970 FW |
5465 | /* |
5466 | * put_prev_task() and pick_next_task() sched | |
5467 | * class method both need to have an up-to-date | |
5468 | * value of rq->clock[_task] | |
5469 | */ | |
5470 | update_rq_clock(rq); | |
5471 | ||
5e16bbc2 | 5472 | for (;;) { |
48c5ccae PZ |
5473 | /* |
5474 | * There's this thread running, bail when that's the only | |
d1ccc66d | 5475 | * remaining thread: |
48c5ccae PZ |
5476 | */ |
5477 | if (rq->nr_running == 1) | |
dd41f596 | 5478 | break; |
48c5ccae | 5479 | |
cbce1a68 | 5480 | /* |
d1ccc66d | 5481 | * pick_next_task() assumes pinned rq->lock: |
cbce1a68 | 5482 | */ |
8a8c69c3 | 5483 | next = pick_next_task(rq, &fake_task, rf); |
48c5ccae | 5484 | BUG_ON(!next); |
5b713a3d | 5485 | put_prev_task(rq, next); |
e692ab53 | 5486 | |
5473e0cc WL |
5487 | /* |
5488 | * Rules for changing task_struct::cpus_allowed are holding | |
5489 | * both pi_lock and rq->lock, such that holding either | |
5490 | * stabilizes the mask. | |
5491 | * | |
5492 | * Drop rq->lock is not quite as disastrous as it usually is | |
5493 | * because !cpu_active at this point, which means load-balance | |
5494 | * will not interfere. Also, stop-machine. | |
5495 | */ | |
8a8c69c3 | 5496 | rq_unlock(rq, rf); |
5473e0cc | 5497 | raw_spin_lock(&next->pi_lock); |
8a8c69c3 | 5498 | rq_relock(rq, rf); |
5473e0cc WL |
5499 | |
5500 | /* | |
5501 | * Since we're inside stop-machine, _nothing_ should have | |
5502 | * changed the task, WARN if weird stuff happened, because in | |
5503 | * that case the above rq->lock drop is a fail too. | |
5504 | */ | |
5505 | if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) { | |
5506 | raw_spin_unlock(&next->pi_lock); | |
5507 | continue; | |
5508 | } | |
5509 | ||
48c5ccae | 5510 | /* Find suitable destination for @next, with force if needed. */ |
5e16bbc2 | 5511 | dest_cpu = select_fallback_rq(dead_rq->cpu, next); |
8a8c69c3 | 5512 | rq = __migrate_task(rq, rf, next, dest_cpu); |
5e16bbc2 | 5513 | if (rq != dead_rq) { |
8a8c69c3 | 5514 | rq_unlock(rq, rf); |
5e16bbc2 | 5515 | rq = dead_rq; |
8a8c69c3 PZ |
5516 | *rf = orf; |
5517 | rq_relock(rq, rf); | |
5e16bbc2 | 5518 | } |
5473e0cc | 5519 | raw_spin_unlock(&next->pi_lock); |
1da177e4 | 5520 | } |
dce48a84 | 5521 | |
48c5ccae | 5522 | rq->stop = stop; |
dce48a84 | 5523 | } |
1da177e4 LT |
5524 | #endif /* CONFIG_HOTPLUG_CPU */ |
5525 | ||
f2cb1360 | 5526 | void set_rq_online(struct rq *rq) |
1f11eb6a GH |
5527 | { |
5528 | if (!rq->online) { | |
5529 | const struct sched_class *class; | |
5530 | ||
c6c4927b | 5531 | cpumask_set_cpu(rq->cpu, rq->rd->online); |
1f11eb6a GH |
5532 | rq->online = 1; |
5533 | ||
5534 | for_each_class(class) { | |
5535 | if (class->rq_online) | |
5536 | class->rq_online(rq); | |
5537 | } | |
5538 | } | |
5539 | } | |
5540 | ||
f2cb1360 | 5541 | void set_rq_offline(struct rq *rq) |
1f11eb6a GH |
5542 | { |
5543 | if (rq->online) { | |
5544 | const struct sched_class *class; | |
5545 | ||
5546 | for_each_class(class) { | |
5547 | if (class->rq_offline) | |
5548 | class->rq_offline(rq); | |
5549 | } | |
5550 | ||
c6c4927b | 5551 | cpumask_clear_cpu(rq->cpu, rq->rd->online); |
1f11eb6a GH |
5552 | rq->online = 0; |
5553 | } | |
5554 | } | |
5555 | ||
9cf7243d | 5556 | static void set_cpu_rq_start_time(unsigned int cpu) |
1da177e4 | 5557 | { |
969c7921 | 5558 | struct rq *rq = cpu_rq(cpu); |
1da177e4 | 5559 | |
a803f026 CM |
5560 | rq->age_stamp = sched_clock_cpu(cpu); |
5561 | } | |
5562 | ||
d1ccc66d IM |
5563 | /* |
5564 | * used to mark begin/end of suspend/resume: | |
5565 | */ | |
5566 | static int num_cpus_frozen; | |
d35be8ba | 5567 | |
1da177e4 | 5568 | /* |
3a101d05 TH |
5569 | * Update cpusets according to cpu_active mask. If cpusets are |
5570 | * disabled, cpuset_update_active_cpus() becomes a simple wrapper | |
5571 | * around partition_sched_domains(). | |
d35be8ba SB |
5572 | * |
5573 | * If we come here as part of a suspend/resume, don't touch cpusets because we | |
5574 | * want to restore it back to its original state upon resume anyway. | |
1da177e4 | 5575 | */ |
40190a78 | 5576 | static void cpuset_cpu_active(void) |
e761b772 | 5577 | { |
40190a78 | 5578 | if (cpuhp_tasks_frozen) { |
d35be8ba SB |
5579 | /* |
5580 | * num_cpus_frozen tracks how many CPUs are involved in suspend | |
5581 | * resume sequence. As long as this is not the last online | |
5582 | * operation in the resume sequence, just build a single sched | |
5583 | * domain, ignoring cpusets. | |
5584 | */ | |
50e76632 PZ |
5585 | partition_sched_domains(1, NULL, NULL); |
5586 | if (--num_cpus_frozen) | |
135fb3e1 | 5587 | return; |
d35be8ba SB |
5588 | /* |
5589 | * This is the last CPU online operation. So fall through and | |
5590 | * restore the original sched domains by considering the | |
5591 | * cpuset configurations. | |
5592 | */ | |
50e76632 | 5593 | cpuset_force_rebuild(); |
3a101d05 | 5594 | } |
30e03acd | 5595 | cpuset_update_active_cpus(); |
3a101d05 | 5596 | } |
e761b772 | 5597 | |
40190a78 | 5598 | static int cpuset_cpu_inactive(unsigned int cpu) |
3a101d05 | 5599 | { |
40190a78 | 5600 | if (!cpuhp_tasks_frozen) { |
06a76fe0 | 5601 | if (dl_cpu_busy(cpu)) |
135fb3e1 | 5602 | return -EBUSY; |
30e03acd | 5603 | cpuset_update_active_cpus(); |
135fb3e1 | 5604 | } else { |
d35be8ba SB |
5605 | num_cpus_frozen++; |
5606 | partition_sched_domains(1, NULL, NULL); | |
e761b772 | 5607 | } |
135fb3e1 | 5608 | return 0; |
e761b772 | 5609 | } |
e761b772 | 5610 | |
40190a78 | 5611 | int sched_cpu_activate(unsigned int cpu) |
135fb3e1 | 5612 | { |
7d976699 | 5613 | struct rq *rq = cpu_rq(cpu); |
8a8c69c3 | 5614 | struct rq_flags rf; |
7d976699 | 5615 | |
40190a78 | 5616 | set_cpu_active(cpu, true); |
135fb3e1 | 5617 | |
40190a78 | 5618 | if (sched_smp_initialized) { |
135fb3e1 | 5619 | sched_domains_numa_masks_set(cpu); |
40190a78 | 5620 | cpuset_cpu_active(); |
e761b772 | 5621 | } |
7d976699 TG |
5622 | |
5623 | /* | |
5624 | * Put the rq online, if not already. This happens: | |
5625 | * | |
5626 | * 1) In the early boot process, because we build the real domains | |
d1ccc66d | 5627 | * after all CPUs have been brought up. |
7d976699 TG |
5628 | * |
5629 | * 2) At runtime, if cpuset_cpu_active() fails to rebuild the | |
5630 | * domains. | |
5631 | */ | |
8a8c69c3 | 5632 | rq_lock_irqsave(rq, &rf); |
7d976699 TG |
5633 | if (rq->rd) { |
5634 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5635 | set_rq_online(rq); | |
5636 | } | |
8a8c69c3 | 5637 | rq_unlock_irqrestore(rq, &rf); |
7d976699 TG |
5638 | |
5639 | update_max_interval(); | |
5640 | ||
40190a78 | 5641 | return 0; |
135fb3e1 TG |
5642 | } |
5643 | ||
40190a78 | 5644 | int sched_cpu_deactivate(unsigned int cpu) |
135fb3e1 | 5645 | { |
135fb3e1 TG |
5646 | int ret; |
5647 | ||
40190a78 | 5648 | set_cpu_active(cpu, false); |
b2454caa PZ |
5649 | /* |
5650 | * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU | |
5651 | * users of this state to go away such that all new such users will | |
5652 | * observe it. | |
5653 | * | |
b2454caa PZ |
5654 | * Do sync before park smpboot threads to take care the rcu boost case. |
5655 | */ | |
d7d34d5e | 5656 | synchronize_rcu_mult(call_rcu, call_rcu_sched); |
40190a78 TG |
5657 | |
5658 | if (!sched_smp_initialized) | |
5659 | return 0; | |
5660 | ||
5661 | ret = cpuset_cpu_inactive(cpu); | |
5662 | if (ret) { | |
5663 | set_cpu_active(cpu, true); | |
5664 | return ret; | |
135fb3e1 | 5665 | } |
40190a78 TG |
5666 | sched_domains_numa_masks_clear(cpu); |
5667 | return 0; | |
135fb3e1 TG |
5668 | } |
5669 | ||
94baf7a5 TG |
5670 | static void sched_rq_cpu_starting(unsigned int cpu) |
5671 | { | |
5672 | struct rq *rq = cpu_rq(cpu); | |
5673 | ||
5674 | rq->calc_load_update = calc_load_update; | |
94baf7a5 TG |
5675 | update_max_interval(); |
5676 | } | |
5677 | ||
135fb3e1 TG |
5678 | int sched_cpu_starting(unsigned int cpu) |
5679 | { | |
5680 | set_cpu_rq_start_time(cpu); | |
94baf7a5 | 5681 | sched_rq_cpu_starting(cpu); |
135fb3e1 | 5682 | return 0; |
e761b772 | 5683 | } |
e761b772 | 5684 | |
f2785ddb TG |
5685 | #ifdef CONFIG_HOTPLUG_CPU |
5686 | int sched_cpu_dying(unsigned int cpu) | |
5687 | { | |
5688 | struct rq *rq = cpu_rq(cpu); | |
8a8c69c3 | 5689 | struct rq_flags rf; |
f2785ddb TG |
5690 | |
5691 | /* Handle pending wakeups and then migrate everything off */ | |
5692 | sched_ttwu_pending(); | |
8a8c69c3 PZ |
5693 | |
5694 | rq_lock_irqsave(rq, &rf); | |
f2785ddb TG |
5695 | if (rq->rd) { |
5696 | BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); | |
5697 | set_rq_offline(rq); | |
5698 | } | |
8a8c69c3 | 5699 | migrate_tasks(rq, &rf); |
f2785ddb | 5700 | BUG_ON(rq->nr_running != 1); |
8a8c69c3 PZ |
5701 | rq_unlock_irqrestore(rq, &rf); |
5702 | ||
f2785ddb TG |
5703 | calc_load_migrate(rq); |
5704 | update_max_interval(); | |
20a5c8cc | 5705 | nohz_balance_exit_idle(cpu); |
e5ef27d0 | 5706 | hrtick_clear(rq); |
f2785ddb TG |
5707 | return 0; |
5708 | } | |
5709 | #endif | |
5710 | ||
1b568f0a PZ |
5711 | #ifdef CONFIG_SCHED_SMT |
5712 | DEFINE_STATIC_KEY_FALSE(sched_smt_present); | |
5713 | ||
5714 | static void sched_init_smt(void) | |
5715 | { | |
5716 | /* | |
5717 | * We've enumerated all CPUs and will assume that if any CPU | |
5718 | * has SMT siblings, CPU0 will too. | |
5719 | */ | |
5720 | if (cpumask_weight(cpu_smt_mask(0)) > 1) | |
5721 | static_branch_enable(&sched_smt_present); | |
5722 | } | |
5723 | #else | |
5724 | static inline void sched_init_smt(void) { } | |
5725 | #endif | |
5726 | ||
1da177e4 LT |
5727 | void __init sched_init_smp(void) |
5728 | { | |
dcc30a35 RR |
5729 | cpumask_var_t non_isolated_cpus; |
5730 | ||
5731 | alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); | |
5c1e1767 | 5732 | |
cb83b629 PZ |
5733 | sched_init_numa(); |
5734 | ||
6acce3ef PZ |
5735 | /* |
5736 | * There's no userspace yet to cause hotplug operations; hence all the | |
d1ccc66d | 5737 | * CPU masks are stable and all blatant races in the below code cannot |
6acce3ef PZ |
5738 | * happen. |
5739 | */ | |
712555ee | 5740 | mutex_lock(&sched_domains_mutex); |
8d5dc512 | 5741 | sched_init_domains(cpu_active_mask); |
dcc30a35 RR |
5742 | cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); |
5743 | if (cpumask_empty(non_isolated_cpus)) | |
5744 | cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); | |
712555ee | 5745 | mutex_unlock(&sched_domains_mutex); |
e761b772 | 5746 | |
5c1e1767 | 5747 | /* Move init over to a non-isolated CPU */ |
dcc30a35 | 5748 | if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) |
5c1e1767 | 5749 | BUG(); |
19978ca6 | 5750 | sched_init_granularity(); |
dcc30a35 | 5751 | free_cpumask_var(non_isolated_cpus); |
4212823f | 5752 | |
0e3900e6 | 5753 | init_sched_rt_class(); |
1baca4ce | 5754 | init_sched_dl_class(); |
1b568f0a PZ |
5755 | |
5756 | sched_init_smt(); | |
5757 | ||
e26fbffd | 5758 | sched_smp_initialized = true; |
1da177e4 | 5759 | } |
e26fbffd TG |
5760 | |
5761 | static int __init migration_init(void) | |
5762 | { | |
94baf7a5 | 5763 | sched_rq_cpu_starting(smp_processor_id()); |
e26fbffd | 5764 | return 0; |
1da177e4 | 5765 | } |
e26fbffd TG |
5766 | early_initcall(migration_init); |
5767 | ||
1da177e4 LT |
5768 | #else |
5769 | void __init sched_init_smp(void) | |
5770 | { | |
19978ca6 | 5771 | sched_init_granularity(); |
1da177e4 LT |
5772 | } |
5773 | #endif /* CONFIG_SMP */ | |
5774 | ||
5775 | int in_sched_functions(unsigned long addr) | |
5776 | { | |
1da177e4 LT |
5777 | return in_lock_functions(addr) || |
5778 | (addr >= (unsigned long)__sched_text_start | |
5779 | && addr < (unsigned long)__sched_text_end); | |
5780 | } | |
5781 | ||
029632fb | 5782 | #ifdef CONFIG_CGROUP_SCHED |
27b4b931 LZ |
5783 | /* |
5784 | * Default task group. | |
5785 | * Every task in system belongs to this group at bootup. | |
5786 | */ | |
029632fb | 5787 | struct task_group root_task_group; |
35cf4e50 | 5788 | LIST_HEAD(task_groups); |
b0367629 WL |
5789 | |
5790 | /* Cacheline aligned slab cache for task_group */ | |
5791 | static struct kmem_cache *task_group_cache __read_mostly; | |
052f1dc7 | 5792 | #endif |
6f505b16 | 5793 | |
e6252c3e | 5794 | DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); |
10e2f1ac | 5795 | DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); |
6f505b16 | 5796 | |
1da177e4 LT |
5797 | void __init sched_init(void) |
5798 | { | |
dd41f596 | 5799 | int i, j; |
434d53b0 MT |
5800 | unsigned long alloc_size = 0, ptr; |
5801 | ||
9881b024 | 5802 | sched_clock_init(); |
5822a454 | 5803 | wait_bit_init(); |
9dcb8b68 | 5804 | |
434d53b0 MT |
5805 | #ifdef CONFIG_FAIR_GROUP_SCHED |
5806 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5807 | #endif | |
5808 | #ifdef CONFIG_RT_GROUP_SCHED | |
5809 | alloc_size += 2 * nr_cpu_ids * sizeof(void **); | |
5810 | #endif | |
434d53b0 | 5811 | if (alloc_size) { |
36b7b6d4 | 5812 | ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); |
434d53b0 MT |
5813 | |
5814 | #ifdef CONFIG_FAIR_GROUP_SCHED | |
07e06b01 | 5815 | root_task_group.se = (struct sched_entity **)ptr; |
434d53b0 MT |
5816 | ptr += nr_cpu_ids * sizeof(void **); |
5817 | ||
07e06b01 | 5818 | root_task_group.cfs_rq = (struct cfs_rq **)ptr; |
434d53b0 | 5819 | ptr += nr_cpu_ids * sizeof(void **); |
eff766a6 | 5820 | |
6d6bc0ad | 5821 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
434d53b0 | 5822 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5823 | root_task_group.rt_se = (struct sched_rt_entity **)ptr; |
434d53b0 MT |
5824 | ptr += nr_cpu_ids * sizeof(void **); |
5825 | ||
07e06b01 | 5826 | root_task_group.rt_rq = (struct rt_rq **)ptr; |
eff766a6 PZ |
5827 | ptr += nr_cpu_ids * sizeof(void **); |
5828 | ||
6d6bc0ad | 5829 | #endif /* CONFIG_RT_GROUP_SCHED */ |
b74e6278 | 5830 | } |
df7c8e84 | 5831 | #ifdef CONFIG_CPUMASK_OFFSTACK |
b74e6278 AT |
5832 | for_each_possible_cpu(i) { |
5833 | per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( | |
5834 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
10e2f1ac PZ |
5835 | per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( |
5836 | cpumask_size(), GFP_KERNEL, cpu_to_node(i)); | |
434d53b0 | 5837 | } |
b74e6278 | 5838 | #endif /* CONFIG_CPUMASK_OFFSTACK */ |
dd41f596 | 5839 | |
d1ccc66d IM |
5840 | init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); |
5841 | init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime()); | |
332ac17e | 5842 | |
57d885fe GH |
5843 | #ifdef CONFIG_SMP |
5844 | init_defrootdomain(); | |
5845 | #endif | |
5846 | ||
d0b27fa7 | 5847 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5848 | init_rt_bandwidth(&root_task_group.rt_bandwidth, |
d0b27fa7 | 5849 | global_rt_period(), global_rt_runtime()); |
6d6bc0ad | 5850 | #endif /* CONFIG_RT_GROUP_SCHED */ |
d0b27fa7 | 5851 | |
7c941438 | 5852 | #ifdef CONFIG_CGROUP_SCHED |
b0367629 WL |
5853 | task_group_cache = KMEM_CACHE(task_group, 0); |
5854 | ||
07e06b01 YZ |
5855 | list_add(&root_task_group.list, &task_groups); |
5856 | INIT_LIST_HEAD(&root_task_group.children); | |
f4d6f6c2 | 5857 | INIT_LIST_HEAD(&root_task_group.siblings); |
5091faa4 | 5858 | autogroup_init(&init_task); |
7c941438 | 5859 | #endif /* CONFIG_CGROUP_SCHED */ |
6f505b16 | 5860 | |
0a945022 | 5861 | for_each_possible_cpu(i) { |
70b97a7f | 5862 | struct rq *rq; |
1da177e4 LT |
5863 | |
5864 | rq = cpu_rq(i); | |
05fa785c | 5865 | raw_spin_lock_init(&rq->lock); |
7897986b | 5866 | rq->nr_running = 0; |
dce48a84 TG |
5867 | rq->calc_load_active = 0; |
5868 | rq->calc_load_update = jiffies + LOAD_FREQ; | |
acb5a9ba | 5869 | init_cfs_rq(&rq->cfs); |
07c54f7a AV |
5870 | init_rt_rq(&rq->rt); |
5871 | init_dl_rq(&rq->dl); | |
dd41f596 | 5872 | #ifdef CONFIG_FAIR_GROUP_SCHED |
029632fb | 5873 | root_task_group.shares = ROOT_TASK_GROUP_LOAD; |
6f505b16 | 5874 | INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); |
9c2791f9 | 5875 | rq->tmp_alone_branch = &rq->leaf_cfs_rq_list; |
354d60c2 | 5876 | /* |
d1ccc66d | 5877 | * How much CPU bandwidth does root_task_group get? |
354d60c2 DG |
5878 | * |
5879 | * In case of task-groups formed thr' the cgroup filesystem, it | |
d1ccc66d IM |
5880 | * gets 100% of the CPU resources in the system. This overall |
5881 | * system CPU resource is divided among the tasks of | |
07e06b01 | 5882 | * root_task_group and its child task-groups in a fair manner, |
354d60c2 DG |
5883 | * based on each entity's (task or task-group's) weight |
5884 | * (se->load.weight). | |
5885 | * | |
07e06b01 | 5886 | * In other words, if root_task_group has 10 tasks of weight |
354d60c2 | 5887 | * 1024) and two child groups A0 and A1 (of weight 1024 each), |
d1ccc66d | 5888 | * then A0's share of the CPU resource is: |
354d60c2 | 5889 | * |
0d905bca | 5890 | * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% |
354d60c2 | 5891 | * |
07e06b01 YZ |
5892 | * We achieve this by letting root_task_group's tasks sit |
5893 | * directly in rq->cfs (i.e root_task_group->se[] = NULL). | |
354d60c2 | 5894 | */ |
ab84d31e | 5895 | init_cfs_bandwidth(&root_task_group.cfs_bandwidth); |
07e06b01 | 5896 | init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); |
354d60c2 DG |
5897 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
5898 | ||
5899 | rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; | |
052f1dc7 | 5900 | #ifdef CONFIG_RT_GROUP_SCHED |
07e06b01 | 5901 | init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); |
dd41f596 | 5902 | #endif |
1da177e4 | 5903 | |
dd41f596 IM |
5904 | for (j = 0; j < CPU_LOAD_IDX_MAX; j++) |
5905 | rq->cpu_load[j] = 0; | |
fdf3e95d | 5906 | |
1da177e4 | 5907 | #ifdef CONFIG_SMP |
41c7ce9a | 5908 | rq->sd = NULL; |
57d885fe | 5909 | rq->rd = NULL; |
ca6d75e6 | 5910 | rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE; |
e3fca9e7 | 5911 | rq->balance_callback = NULL; |
1da177e4 | 5912 | rq->active_balance = 0; |
dd41f596 | 5913 | rq->next_balance = jiffies; |
1da177e4 | 5914 | rq->push_cpu = 0; |
0a2966b4 | 5915 | rq->cpu = i; |
1f11eb6a | 5916 | rq->online = 0; |
eae0c9df MG |
5917 | rq->idle_stamp = 0; |
5918 | rq->avg_idle = 2*sysctl_sched_migration_cost; | |
9bd721c5 | 5919 | rq->max_idle_balance_cost = sysctl_sched_migration_cost; |
367456c7 PZ |
5920 | |
5921 | INIT_LIST_HEAD(&rq->cfs_tasks); | |
5922 | ||
dc938520 | 5923 | rq_attach_root(rq, &def_root_domain); |
3451d024 | 5924 | #ifdef CONFIG_NO_HZ_COMMON |
9fd81dd5 | 5925 | rq->last_load_update_tick = jiffies; |
1c792db7 | 5926 | rq->nohz_flags = 0; |
83cd4fe2 | 5927 | #endif |
265f22a9 FW |
5928 | #ifdef CONFIG_NO_HZ_FULL |
5929 | rq->last_sched_tick = 0; | |
5930 | #endif | |
9fd81dd5 | 5931 | #endif /* CONFIG_SMP */ |
8f4d37ec | 5932 | init_rq_hrtick(rq); |
1da177e4 | 5933 | atomic_set(&rq->nr_iowait, 0); |
1da177e4 LT |
5934 | } |
5935 | ||
2dd73a4f | 5936 | set_load_weight(&init_task); |
b50f60ce | 5937 | |
1da177e4 LT |
5938 | /* |
5939 | * The boot idle thread does lazy MMU switching as well: | |
5940 | */ | |
f1f10076 | 5941 | mmgrab(&init_mm); |
1da177e4 LT |
5942 | enter_lazy_tlb(&init_mm, current); |
5943 | ||
5944 | /* | |
5945 | * Make us the idle thread. Technically, schedule() should not be | |
5946 | * called from this thread, however somewhere below it might be, | |
5947 | * but because we are the idle thread, we just pick up running again | |
5948 | * when this runqueue becomes "idle". | |
5949 | */ | |
5950 | init_idle(current, smp_processor_id()); | |
dce48a84 TG |
5951 | |
5952 | calc_load_update = jiffies + LOAD_FREQ; | |
5953 | ||
bf4d83f6 | 5954 | #ifdef CONFIG_SMP |
bdddd296 RR |
5955 | /* May be allocated at isolcpus cmdline parse time */ |
5956 | if (cpu_isolated_map == NULL) | |
5957 | zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); | |
29d5e047 | 5958 | idle_thread_set_boot_cpu(); |
9cf7243d | 5959 | set_cpu_rq_start_time(smp_processor_id()); |
029632fb PZ |
5960 | #endif |
5961 | init_sched_fair_class(); | |
6a7b3dc3 | 5962 | |
4698f88c JP |
5963 | init_schedstats(); |
5964 | ||
6892b75e | 5965 | scheduler_running = 1; |
1da177e4 LT |
5966 | } |
5967 | ||
d902db1e | 5968 | #ifdef CONFIG_DEBUG_ATOMIC_SLEEP |
e4aafea2 FW |
5969 | static inline int preempt_count_equals(int preempt_offset) |
5970 | { | |
da7142e2 | 5971 | int nested = preempt_count() + rcu_preempt_depth(); |
e4aafea2 | 5972 | |
4ba8216c | 5973 | return (nested == preempt_offset); |
e4aafea2 FW |
5974 | } |
5975 | ||
d894837f | 5976 | void __might_sleep(const char *file, int line, int preempt_offset) |
1da177e4 | 5977 | { |
8eb23b9f PZ |
5978 | /* |
5979 | * Blocking primitives will set (and therefore destroy) current->state, | |
5980 | * since we will exit with TASK_RUNNING make sure we enter with it, | |
5981 | * otherwise we will destroy state. | |
5982 | */ | |
00845eb9 | 5983 | WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change, |
8eb23b9f PZ |
5984 | "do not call blocking ops when !TASK_RUNNING; " |
5985 | "state=%lx set at [<%p>] %pS\n", | |
5986 | current->state, | |
5987 | (void *)current->task_state_change, | |
00845eb9 | 5988 | (void *)current->task_state_change); |
8eb23b9f | 5989 | |
3427445a PZ |
5990 | ___might_sleep(file, line, preempt_offset); |
5991 | } | |
5992 | EXPORT_SYMBOL(__might_sleep); | |
5993 | ||
5994 | void ___might_sleep(const char *file, int line, int preempt_offset) | |
1da177e4 | 5995 | { |
d1ccc66d IM |
5996 | /* Ratelimiting timestamp: */ |
5997 | static unsigned long prev_jiffy; | |
5998 | ||
d1c6d149 | 5999 | unsigned long preempt_disable_ip; |
1da177e4 | 6000 | |
d1ccc66d IM |
6001 | /* WARN_ON_ONCE() by default, no rate limit required: */ |
6002 | rcu_sleep_check(); | |
6003 | ||
db273be2 TG |
6004 | if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && |
6005 | !is_idle_task(current)) || | |
1c3c5eab TG |
6006 | system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING || |
6007 | oops_in_progress) | |
aef745fc | 6008 | return; |
1c3c5eab | 6009 | |
aef745fc IM |
6010 | if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) |
6011 | return; | |
6012 | prev_jiffy = jiffies; | |
6013 | ||
d1ccc66d | 6014 | /* Save this before calling printk(), since that will clobber it: */ |
d1c6d149 VN |
6015 | preempt_disable_ip = get_preempt_disable_ip(current); |
6016 | ||
3df0fc5b PZ |
6017 | printk(KERN_ERR |
6018 | "BUG: sleeping function called from invalid context at %s:%d\n", | |
6019 | file, line); | |
6020 | printk(KERN_ERR | |
6021 | "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", | |
6022 | in_atomic(), irqs_disabled(), | |
6023 | current->pid, current->comm); | |
aef745fc | 6024 | |
a8b686b3 ES |
6025 | if (task_stack_end_corrupted(current)) |
6026 | printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); | |
6027 | ||
aef745fc IM |
6028 | debug_show_held_locks(current); |
6029 | if (irqs_disabled()) | |
6030 | print_irqtrace_events(current); | |
d1c6d149 VN |
6031 | if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) |
6032 | && !preempt_count_equals(preempt_offset)) { | |
8f47b187 | 6033 | pr_err("Preemption disabled at:"); |
d1c6d149 | 6034 | print_ip_sym(preempt_disable_ip); |
8f47b187 TG |
6035 | pr_cont("\n"); |
6036 | } | |
aef745fc | 6037 | dump_stack(); |
f0b22e39 | 6038 | add_taint(TAINT_WARN, LOCKDEP_STILL_OK); |
1da177e4 | 6039 | } |
3427445a | 6040 | EXPORT_SYMBOL(___might_sleep); |
1da177e4 LT |
6041 | #endif |
6042 | ||
6043 | #ifdef CONFIG_MAGIC_SYSRQ | |
dbc7f069 | 6044 | void normalize_rt_tasks(void) |
3a5e4dc1 | 6045 | { |
dbc7f069 | 6046 | struct task_struct *g, *p; |
d50dde5a DF |
6047 | struct sched_attr attr = { |
6048 | .sched_policy = SCHED_NORMAL, | |
6049 | }; | |
1da177e4 | 6050 | |
3472eaa1 | 6051 | read_lock(&tasklist_lock); |
5d07f420 | 6052 | for_each_process_thread(g, p) { |
178be793 IM |
6053 | /* |
6054 | * Only normalize user tasks: | |
6055 | */ | |
3472eaa1 | 6056 | if (p->flags & PF_KTHREAD) |
178be793 IM |
6057 | continue; |
6058 | ||
4fa8d299 JP |
6059 | p->se.exec_start = 0; |
6060 | schedstat_set(p->se.statistics.wait_start, 0); | |
6061 | schedstat_set(p->se.statistics.sleep_start, 0); | |
6062 | schedstat_set(p->se.statistics.block_start, 0); | |
dd41f596 | 6063 | |
aab03e05 | 6064 | if (!dl_task(p) && !rt_task(p)) { |
dd41f596 IM |
6065 | /* |
6066 | * Renice negative nice level userspace | |
6067 | * tasks back to 0: | |
6068 | */ | |
3472eaa1 | 6069 | if (task_nice(p) < 0) |
dd41f596 | 6070 | set_user_nice(p, 0); |
1da177e4 | 6071 | continue; |
dd41f596 | 6072 | } |
1da177e4 | 6073 | |
dbc7f069 | 6074 | __sched_setscheduler(p, &attr, false, false); |
5d07f420 | 6075 | } |
3472eaa1 | 6076 | read_unlock(&tasklist_lock); |
1da177e4 LT |
6077 | } |
6078 | ||
6079 | #endif /* CONFIG_MAGIC_SYSRQ */ | |
1df5c10a | 6080 | |
67fc4e0c | 6081 | #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) |
1df5c10a | 6082 | /* |
67fc4e0c | 6083 | * These functions are only useful for the IA64 MCA handling, or kdb. |
1df5c10a LT |
6084 | * |
6085 | * They can only be called when the whole system has been | |
6086 | * stopped - every CPU needs to be quiescent, and no scheduling | |
6087 | * activity can take place. Using them for anything else would | |
6088 | * be a serious bug, and as a result, they aren't even visible | |
6089 | * under any other configuration. | |
6090 | */ | |
6091 | ||
6092 | /** | |
d1ccc66d | 6093 | * curr_task - return the current task for a given CPU. |
1df5c10a LT |
6094 | * @cpu: the processor in question. |
6095 | * | |
6096 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
e69f6186 YB |
6097 | * |
6098 | * Return: The current task for @cpu. | |
1df5c10a | 6099 | */ |
36c8b586 | 6100 | struct task_struct *curr_task(int cpu) |
1df5c10a LT |
6101 | { |
6102 | return cpu_curr(cpu); | |
6103 | } | |
6104 | ||
67fc4e0c JW |
6105 | #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ |
6106 | ||
6107 | #ifdef CONFIG_IA64 | |
1df5c10a | 6108 | /** |
d1ccc66d | 6109 | * set_curr_task - set the current task for a given CPU. |
1df5c10a LT |
6110 | * @cpu: the processor in question. |
6111 | * @p: the task pointer to set. | |
6112 | * | |
6113 | * Description: This function must only be used when non-maskable interrupts | |
41a2d6cf | 6114 | * are serviced on a separate stack. It allows the architecture to switch the |
d1ccc66d | 6115 | * notion of the current task on a CPU in a non-blocking manner. This function |
1df5c10a LT |
6116 | * must be called with all CPU's synchronized, and interrupts disabled, the |
6117 | * and caller must save the original value of the current task (see | |
6118 | * curr_task() above) and restore that value before reenabling interrupts and | |
6119 | * re-starting the system. | |
6120 | * | |
6121 | * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! | |
6122 | */ | |
a458ae2e | 6123 | void ia64_set_curr_task(int cpu, struct task_struct *p) |
1df5c10a LT |
6124 | { |
6125 | cpu_curr(cpu) = p; | |
6126 | } | |
6127 | ||
6128 | #endif | |
29f59db3 | 6129 | |
7c941438 | 6130 | #ifdef CONFIG_CGROUP_SCHED |
029632fb PZ |
6131 | /* task_group_lock serializes the addition/removal of task groups */ |
6132 | static DEFINE_SPINLOCK(task_group_lock); | |
6133 | ||
2f5177f0 | 6134 | static void sched_free_group(struct task_group *tg) |
bccbe08a PZ |
6135 | { |
6136 | free_fair_sched_group(tg); | |
6137 | free_rt_sched_group(tg); | |
e9aa1dd1 | 6138 | autogroup_free(tg); |
b0367629 | 6139 | kmem_cache_free(task_group_cache, tg); |
bccbe08a PZ |
6140 | } |
6141 | ||
6142 | /* allocate runqueue etc for a new task group */ | |
ec7dc8ac | 6143 | struct task_group *sched_create_group(struct task_group *parent) |
bccbe08a PZ |
6144 | { |
6145 | struct task_group *tg; | |
bccbe08a | 6146 | |
b0367629 | 6147 | tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO); |
bccbe08a PZ |
6148 | if (!tg) |
6149 | return ERR_PTR(-ENOMEM); | |
6150 | ||
ec7dc8ac | 6151 | if (!alloc_fair_sched_group(tg, parent)) |
bccbe08a PZ |
6152 | goto err; |
6153 | ||
ec7dc8ac | 6154 | if (!alloc_rt_sched_group(tg, parent)) |
bccbe08a PZ |
6155 | goto err; |
6156 | ||
ace783b9 LZ |
6157 | return tg; |
6158 | ||
6159 | err: | |
2f5177f0 | 6160 | sched_free_group(tg); |
ace783b9 LZ |
6161 | return ERR_PTR(-ENOMEM); |
6162 | } | |
6163 | ||
6164 | void sched_online_group(struct task_group *tg, struct task_group *parent) | |
6165 | { | |
6166 | unsigned long flags; | |
6167 | ||
8ed36996 | 6168 | spin_lock_irqsave(&task_group_lock, flags); |
6f505b16 | 6169 | list_add_rcu(&tg->list, &task_groups); |
f473aa5e | 6170 | |
d1ccc66d IM |
6171 | /* Root should already exist: */ |
6172 | WARN_ON(!parent); | |
f473aa5e PZ |
6173 | |
6174 | tg->parent = parent; | |
f473aa5e | 6175 | INIT_LIST_HEAD(&tg->children); |
09f2724a | 6176 | list_add_rcu(&tg->siblings, &parent->children); |
8ed36996 | 6177 | spin_unlock_irqrestore(&task_group_lock, flags); |
8663e24d PZ |
6178 | |
6179 | online_fair_sched_group(tg); | |
29f59db3 SV |
6180 | } |
6181 | ||
9b5b7751 | 6182 | /* rcu callback to free various structures associated with a task group */ |
2f5177f0 | 6183 | static void sched_free_group_rcu(struct rcu_head *rhp) |
29f59db3 | 6184 | { |
d1ccc66d | 6185 | /* Now it should be safe to free those cfs_rqs: */ |
2f5177f0 | 6186 | sched_free_group(container_of(rhp, struct task_group, rcu)); |
29f59db3 SV |
6187 | } |
6188 | ||
4cf86d77 | 6189 | void sched_destroy_group(struct task_group *tg) |
ace783b9 | 6190 | { |
d1ccc66d | 6191 | /* Wait for possible concurrent references to cfs_rqs complete: */ |
2f5177f0 | 6192 | call_rcu(&tg->rcu, sched_free_group_rcu); |
ace783b9 LZ |
6193 | } |
6194 | ||
6195 | void sched_offline_group(struct task_group *tg) | |
29f59db3 | 6196 | { |
8ed36996 | 6197 | unsigned long flags; |
29f59db3 | 6198 | |
d1ccc66d | 6199 | /* End participation in shares distribution: */ |
6fe1f348 | 6200 | unregister_fair_sched_group(tg); |
3d4b47b4 PZ |
6201 | |
6202 | spin_lock_irqsave(&task_group_lock, flags); | |
6f505b16 | 6203 | list_del_rcu(&tg->list); |
f473aa5e | 6204 | list_del_rcu(&tg->siblings); |
8ed36996 | 6205 | spin_unlock_irqrestore(&task_group_lock, flags); |
29f59db3 SV |
6206 | } |
6207 | ||
ea86cb4b | 6208 | static void sched_change_group(struct task_struct *tsk, int type) |
29f59db3 | 6209 | { |
8323f26c | 6210 | struct task_group *tg; |
29f59db3 | 6211 | |
f7b8a47d KT |
6212 | /* |
6213 | * All callers are synchronized by task_rq_lock(); we do not use RCU | |
6214 | * which is pointless here. Thus, we pass "true" to task_css_check() | |
6215 | * to prevent lockdep warnings. | |
6216 | */ | |
6217 | tg = container_of(task_css_check(tsk, cpu_cgrp_id, true), | |
8323f26c PZ |
6218 | struct task_group, css); |
6219 | tg = autogroup_task_group(tsk, tg); | |
6220 | tsk->sched_task_group = tg; | |
6221 | ||
810b3817 | 6222 | #ifdef CONFIG_FAIR_GROUP_SCHED |
ea86cb4b VG |
6223 | if (tsk->sched_class->task_change_group) |
6224 | tsk->sched_class->task_change_group(tsk, type); | |
b2b5ce02 | 6225 | else |
810b3817 | 6226 | #endif |
b2b5ce02 | 6227 | set_task_rq(tsk, task_cpu(tsk)); |
ea86cb4b VG |
6228 | } |
6229 | ||
6230 | /* | |
6231 | * Change task's runqueue when it moves between groups. | |
6232 | * | |
6233 | * The caller of this function should have put the task in its new group by | |
6234 | * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect | |
6235 | * its new group. | |
6236 | */ | |
6237 | void sched_move_task(struct task_struct *tsk) | |
6238 | { | |
7a57f32a PZ |
6239 | int queued, running, queue_flags = |
6240 | DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; | |
ea86cb4b VG |
6241 | struct rq_flags rf; |
6242 | struct rq *rq; | |
6243 | ||
6244 | rq = task_rq_lock(tsk, &rf); | |
1b1d6225 | 6245 | update_rq_clock(rq); |
ea86cb4b VG |
6246 | |
6247 | running = task_current(rq, tsk); | |
6248 | queued = task_on_rq_queued(tsk); | |
6249 | ||
6250 | if (queued) | |
7a57f32a | 6251 | dequeue_task(rq, tsk, queue_flags); |
bb3bac2c | 6252 | if (running) |
ea86cb4b VG |
6253 | put_prev_task(rq, tsk); |
6254 | ||
6255 | sched_change_group(tsk, TASK_MOVE_GROUP); | |
810b3817 | 6256 | |
da0c1e65 | 6257 | if (queued) |
7a57f32a | 6258 | enqueue_task(rq, tsk, queue_flags); |
bb3bac2c | 6259 | if (running) |
b2bf6c31 | 6260 | set_curr_task(rq, tsk); |
29f59db3 | 6261 | |
eb580751 | 6262 | task_rq_unlock(rq, tsk, &rf); |
29f59db3 | 6263 | } |
68318b8e | 6264 | |
a7c6d554 | 6265 | static inline struct task_group *css_tg(struct cgroup_subsys_state *css) |
68318b8e | 6266 | { |
a7c6d554 | 6267 | return css ? container_of(css, struct task_group, css) : NULL; |
68318b8e SV |
6268 | } |
6269 | ||
eb95419b TH |
6270 | static struct cgroup_subsys_state * |
6271 | cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) | |
68318b8e | 6272 | { |
eb95419b TH |
6273 | struct task_group *parent = css_tg(parent_css); |
6274 | struct task_group *tg; | |
68318b8e | 6275 | |
eb95419b | 6276 | if (!parent) { |
68318b8e | 6277 | /* This is early initialization for the top cgroup */ |
07e06b01 | 6278 | return &root_task_group.css; |
68318b8e SV |
6279 | } |
6280 | ||
ec7dc8ac | 6281 | tg = sched_create_group(parent); |
68318b8e SV |
6282 | if (IS_ERR(tg)) |
6283 | return ERR_PTR(-ENOMEM); | |
6284 | ||
68318b8e SV |
6285 | return &tg->css; |
6286 | } | |
6287 | ||
96b77745 KK |
6288 | /* Expose task group only after completing cgroup initialization */ |
6289 | static int cpu_cgroup_css_online(struct cgroup_subsys_state *css) | |
6290 | { | |
6291 | struct task_group *tg = css_tg(css); | |
6292 | struct task_group *parent = css_tg(css->parent); | |
6293 | ||
6294 | if (parent) | |
6295 | sched_online_group(tg, parent); | |
6296 | return 0; | |
6297 | } | |
6298 | ||
2f5177f0 | 6299 | static void cpu_cgroup_css_released(struct cgroup_subsys_state *css) |
ace783b9 | 6300 | { |
eb95419b | 6301 | struct task_group *tg = css_tg(css); |
ace783b9 | 6302 | |
2f5177f0 | 6303 | sched_offline_group(tg); |
ace783b9 LZ |
6304 | } |
6305 | ||
eb95419b | 6306 | static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) |
68318b8e | 6307 | { |
eb95419b | 6308 | struct task_group *tg = css_tg(css); |
68318b8e | 6309 | |
2f5177f0 PZ |
6310 | /* |
6311 | * Relies on the RCU grace period between css_released() and this. | |
6312 | */ | |
6313 | sched_free_group(tg); | |
ace783b9 LZ |
6314 | } |
6315 | ||
ea86cb4b VG |
6316 | /* |
6317 | * This is called before wake_up_new_task(), therefore we really only | |
6318 | * have to set its group bits, all the other stuff does not apply. | |
6319 | */ | |
b53202e6 | 6320 | static void cpu_cgroup_fork(struct task_struct *task) |
eeb61e53 | 6321 | { |
ea86cb4b VG |
6322 | struct rq_flags rf; |
6323 | struct rq *rq; | |
6324 | ||
6325 | rq = task_rq_lock(task, &rf); | |
6326 | ||
80f5c1b8 | 6327 | update_rq_clock(rq); |
ea86cb4b VG |
6328 | sched_change_group(task, TASK_SET_GROUP); |
6329 | ||
6330 | task_rq_unlock(rq, task, &rf); | |
eeb61e53 KT |
6331 | } |
6332 | ||
1f7dd3e5 | 6333 | static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) |
68318b8e | 6334 | { |
bb9d97b6 | 6335 | struct task_struct *task; |
1f7dd3e5 | 6336 | struct cgroup_subsys_state *css; |
7dc603c9 | 6337 | int ret = 0; |
bb9d97b6 | 6338 | |
1f7dd3e5 | 6339 | cgroup_taskset_for_each(task, css, tset) { |
b68aa230 | 6340 | #ifdef CONFIG_RT_GROUP_SCHED |
eb95419b | 6341 | if (!sched_rt_can_attach(css_tg(css), task)) |
bb9d97b6 | 6342 | return -EINVAL; |
b68aa230 | 6343 | #else |
bb9d97b6 TH |
6344 | /* We don't support RT-tasks being in separate groups */ |
6345 | if (task->sched_class != &fair_sched_class) | |
6346 | return -EINVAL; | |
b68aa230 | 6347 | #endif |
7dc603c9 PZ |
6348 | /* |
6349 | * Serialize against wake_up_new_task() such that if its | |
6350 | * running, we're sure to observe its full state. | |
6351 | */ | |
6352 | raw_spin_lock_irq(&task->pi_lock); | |
6353 | /* | |
6354 | * Avoid calling sched_move_task() before wake_up_new_task() | |
6355 | * has happened. This would lead to problems with PELT, due to | |
6356 | * move wanting to detach+attach while we're not attached yet. | |
6357 | */ | |
6358 | if (task->state == TASK_NEW) | |
6359 | ret = -EINVAL; | |
6360 | raw_spin_unlock_irq(&task->pi_lock); | |
6361 | ||
6362 | if (ret) | |
6363 | break; | |
bb9d97b6 | 6364 | } |
7dc603c9 | 6365 | return ret; |
be367d09 | 6366 | } |
68318b8e | 6367 | |
1f7dd3e5 | 6368 | static void cpu_cgroup_attach(struct cgroup_taskset *tset) |
68318b8e | 6369 | { |
bb9d97b6 | 6370 | struct task_struct *task; |
1f7dd3e5 | 6371 | struct cgroup_subsys_state *css; |
bb9d97b6 | 6372 | |
1f7dd3e5 | 6373 | cgroup_taskset_for_each(task, css, tset) |
bb9d97b6 | 6374 | sched_move_task(task); |
68318b8e SV |
6375 | } |
6376 | ||
052f1dc7 | 6377 | #ifdef CONFIG_FAIR_GROUP_SCHED |
182446d0 TH |
6378 | static int cpu_shares_write_u64(struct cgroup_subsys_state *css, |
6379 | struct cftype *cftype, u64 shareval) | |
68318b8e | 6380 | { |
182446d0 | 6381 | return sched_group_set_shares(css_tg(css), scale_load(shareval)); |
68318b8e SV |
6382 | } |
6383 | ||
182446d0 TH |
6384 | static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css, |
6385 | struct cftype *cft) | |
68318b8e | 6386 | { |
182446d0 | 6387 | struct task_group *tg = css_tg(css); |
68318b8e | 6388 | |
c8b28116 | 6389 | return (u64) scale_load_down(tg->shares); |
68318b8e | 6390 | } |
ab84d31e PT |
6391 | |
6392 | #ifdef CONFIG_CFS_BANDWIDTH | |
a790de99 PT |
6393 | static DEFINE_MUTEX(cfs_constraints_mutex); |
6394 | ||
ab84d31e PT |
6395 | const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ |
6396 | const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ | |
6397 | ||
a790de99 PT |
6398 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); |
6399 | ||
ab84d31e PT |
6400 | static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) |
6401 | { | |
56f570e5 | 6402 | int i, ret = 0, runtime_enabled, runtime_was_enabled; |
029632fb | 6403 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
ab84d31e PT |
6404 | |
6405 | if (tg == &root_task_group) | |
6406 | return -EINVAL; | |
6407 | ||
6408 | /* | |
6409 | * Ensure we have at some amount of bandwidth every period. This is | |
6410 | * to prevent reaching a state of large arrears when throttled via | |
6411 | * entity_tick() resulting in prolonged exit starvation. | |
6412 | */ | |
6413 | if (quota < min_cfs_quota_period || period < min_cfs_quota_period) | |
6414 | return -EINVAL; | |
6415 | ||
6416 | /* | |
6417 | * Likewise, bound things on the otherside by preventing insane quota | |
6418 | * periods. This also allows us to normalize in computing quota | |
6419 | * feasibility. | |
6420 | */ | |
6421 | if (period > max_cfs_quota_period) | |
6422 | return -EINVAL; | |
6423 | ||
0e59bdae KT |
6424 | /* |
6425 | * Prevent race between setting of cfs_rq->runtime_enabled and | |
6426 | * unthrottle_offline_cfs_rqs(). | |
6427 | */ | |
6428 | get_online_cpus(); | |
a790de99 PT |
6429 | mutex_lock(&cfs_constraints_mutex); |
6430 | ret = __cfs_schedulable(tg, period, quota); | |
6431 | if (ret) | |
6432 | goto out_unlock; | |
6433 | ||
58088ad0 | 6434 | runtime_enabled = quota != RUNTIME_INF; |
56f570e5 | 6435 | runtime_was_enabled = cfs_b->quota != RUNTIME_INF; |
1ee14e6c BS |
6436 | /* |
6437 | * If we need to toggle cfs_bandwidth_used, off->on must occur | |
6438 | * before making related changes, and on->off must occur afterwards | |
6439 | */ | |
6440 | if (runtime_enabled && !runtime_was_enabled) | |
6441 | cfs_bandwidth_usage_inc(); | |
ab84d31e PT |
6442 | raw_spin_lock_irq(&cfs_b->lock); |
6443 | cfs_b->period = ns_to_ktime(period); | |
6444 | cfs_b->quota = quota; | |
58088ad0 | 6445 | |
a9cf55b2 | 6446 | __refill_cfs_bandwidth_runtime(cfs_b); |
d1ccc66d IM |
6447 | |
6448 | /* Restart the period timer (if active) to handle new period expiry: */ | |
77a4d1a1 PZ |
6449 | if (runtime_enabled) |
6450 | start_cfs_bandwidth(cfs_b); | |
d1ccc66d | 6451 | |
ab84d31e PT |
6452 | raw_spin_unlock_irq(&cfs_b->lock); |
6453 | ||
0e59bdae | 6454 | for_each_online_cpu(i) { |
ab84d31e | 6455 | struct cfs_rq *cfs_rq = tg->cfs_rq[i]; |
029632fb | 6456 | struct rq *rq = cfs_rq->rq; |
8a8c69c3 | 6457 | struct rq_flags rf; |
ab84d31e | 6458 | |
8a8c69c3 | 6459 | rq_lock_irq(rq, &rf); |
58088ad0 | 6460 | cfs_rq->runtime_enabled = runtime_enabled; |
ab84d31e | 6461 | cfs_rq->runtime_remaining = 0; |
671fd9da | 6462 | |
029632fb | 6463 | if (cfs_rq->throttled) |
671fd9da | 6464 | unthrottle_cfs_rq(cfs_rq); |
8a8c69c3 | 6465 | rq_unlock_irq(rq, &rf); |
ab84d31e | 6466 | } |
1ee14e6c BS |
6467 | if (runtime_was_enabled && !runtime_enabled) |
6468 | cfs_bandwidth_usage_dec(); | |
a790de99 PT |
6469 | out_unlock: |
6470 | mutex_unlock(&cfs_constraints_mutex); | |
0e59bdae | 6471 | put_online_cpus(); |
ab84d31e | 6472 | |
a790de99 | 6473 | return ret; |
ab84d31e PT |
6474 | } |
6475 | ||
6476 | int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) | |
6477 | { | |
6478 | u64 quota, period; | |
6479 | ||
029632fb | 6480 | period = ktime_to_ns(tg->cfs_bandwidth.period); |
ab84d31e PT |
6481 | if (cfs_quota_us < 0) |
6482 | quota = RUNTIME_INF; | |
6483 | else | |
6484 | quota = (u64)cfs_quota_us * NSEC_PER_USEC; | |
6485 | ||
6486 | return tg_set_cfs_bandwidth(tg, period, quota); | |
6487 | } | |
6488 | ||
6489 | long tg_get_cfs_quota(struct task_group *tg) | |
6490 | { | |
6491 | u64 quota_us; | |
6492 | ||
029632fb | 6493 | if (tg->cfs_bandwidth.quota == RUNTIME_INF) |
ab84d31e PT |
6494 | return -1; |
6495 | ||
029632fb | 6496 | quota_us = tg->cfs_bandwidth.quota; |
ab84d31e PT |
6497 | do_div(quota_us, NSEC_PER_USEC); |
6498 | ||
6499 | return quota_us; | |
6500 | } | |
6501 | ||
6502 | int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) | |
6503 | { | |
6504 | u64 quota, period; | |
6505 | ||
6506 | period = (u64)cfs_period_us * NSEC_PER_USEC; | |
029632fb | 6507 | quota = tg->cfs_bandwidth.quota; |
ab84d31e | 6508 | |
ab84d31e PT |
6509 | return tg_set_cfs_bandwidth(tg, period, quota); |
6510 | } | |
6511 | ||
6512 | long tg_get_cfs_period(struct task_group *tg) | |
6513 | { | |
6514 | u64 cfs_period_us; | |
6515 | ||
029632fb | 6516 | cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); |
ab84d31e PT |
6517 | do_div(cfs_period_us, NSEC_PER_USEC); |
6518 | ||
6519 | return cfs_period_us; | |
6520 | } | |
6521 | ||
182446d0 TH |
6522 | static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css, |
6523 | struct cftype *cft) | |
ab84d31e | 6524 | { |
182446d0 | 6525 | return tg_get_cfs_quota(css_tg(css)); |
ab84d31e PT |
6526 | } |
6527 | ||
182446d0 TH |
6528 | static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css, |
6529 | struct cftype *cftype, s64 cfs_quota_us) | |
ab84d31e | 6530 | { |
182446d0 | 6531 | return tg_set_cfs_quota(css_tg(css), cfs_quota_us); |
ab84d31e PT |
6532 | } |
6533 | ||
182446d0 TH |
6534 | static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css, |
6535 | struct cftype *cft) | |
ab84d31e | 6536 | { |
182446d0 | 6537 | return tg_get_cfs_period(css_tg(css)); |
ab84d31e PT |
6538 | } |
6539 | ||
182446d0 TH |
6540 | static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css, |
6541 | struct cftype *cftype, u64 cfs_period_us) | |
ab84d31e | 6542 | { |
182446d0 | 6543 | return tg_set_cfs_period(css_tg(css), cfs_period_us); |
ab84d31e PT |
6544 | } |
6545 | ||
a790de99 PT |
6546 | struct cfs_schedulable_data { |
6547 | struct task_group *tg; | |
6548 | u64 period, quota; | |
6549 | }; | |
6550 | ||
6551 | /* | |
6552 | * normalize group quota/period to be quota/max_period | |
6553 | * note: units are usecs | |
6554 | */ | |
6555 | static u64 normalize_cfs_quota(struct task_group *tg, | |
6556 | struct cfs_schedulable_data *d) | |
6557 | { | |
6558 | u64 quota, period; | |
6559 | ||
6560 | if (tg == d->tg) { | |
6561 | period = d->period; | |
6562 | quota = d->quota; | |
6563 | } else { | |
6564 | period = tg_get_cfs_period(tg); | |
6565 | quota = tg_get_cfs_quota(tg); | |
6566 | } | |
6567 | ||
6568 | /* note: these should typically be equivalent */ | |
6569 | if (quota == RUNTIME_INF || quota == -1) | |
6570 | return RUNTIME_INF; | |
6571 | ||
6572 | return to_ratio(period, quota); | |
6573 | } | |
6574 | ||
6575 | static int tg_cfs_schedulable_down(struct task_group *tg, void *data) | |
6576 | { | |
6577 | struct cfs_schedulable_data *d = data; | |
029632fb | 6578 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
a790de99 PT |
6579 | s64 quota = 0, parent_quota = -1; |
6580 | ||
6581 | if (!tg->parent) { | |
6582 | quota = RUNTIME_INF; | |
6583 | } else { | |
029632fb | 6584 | struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; |
a790de99 PT |
6585 | |
6586 | quota = normalize_cfs_quota(tg, d); | |
9c58c79a | 6587 | parent_quota = parent_b->hierarchical_quota; |
a790de99 PT |
6588 | |
6589 | /* | |
d1ccc66d IM |
6590 | * Ensure max(child_quota) <= parent_quota, inherit when no |
6591 | * limit is set: | |
a790de99 PT |
6592 | */ |
6593 | if (quota == RUNTIME_INF) | |
6594 | quota = parent_quota; | |
6595 | else if (parent_quota != RUNTIME_INF && quota > parent_quota) | |
6596 | return -EINVAL; | |
6597 | } | |
9c58c79a | 6598 | cfs_b->hierarchical_quota = quota; |
a790de99 PT |
6599 | |
6600 | return 0; | |
6601 | } | |
6602 | ||
6603 | static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) | |
6604 | { | |
8277434e | 6605 | int ret; |
a790de99 PT |
6606 | struct cfs_schedulable_data data = { |
6607 | .tg = tg, | |
6608 | .period = period, | |
6609 | .quota = quota, | |
6610 | }; | |
6611 | ||
6612 | if (quota != RUNTIME_INF) { | |
6613 | do_div(data.period, NSEC_PER_USEC); | |
6614 | do_div(data.quota, NSEC_PER_USEC); | |
6615 | } | |
6616 | ||
8277434e PT |
6617 | rcu_read_lock(); |
6618 | ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); | |
6619 | rcu_read_unlock(); | |
6620 | ||
6621 | return ret; | |
a790de99 | 6622 | } |
e8da1b18 | 6623 | |
2da8ca82 | 6624 | static int cpu_stats_show(struct seq_file *sf, void *v) |
e8da1b18 | 6625 | { |
2da8ca82 | 6626 | struct task_group *tg = css_tg(seq_css(sf)); |
029632fb | 6627 | struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; |
e8da1b18 | 6628 | |
44ffc75b TH |
6629 | seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods); |
6630 | seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled); | |
6631 | seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time); | |
e8da1b18 NR |
6632 | |
6633 | return 0; | |
6634 | } | |
ab84d31e | 6635 | #endif /* CONFIG_CFS_BANDWIDTH */ |
6d6bc0ad | 6636 | #endif /* CONFIG_FAIR_GROUP_SCHED */ |
68318b8e | 6637 | |
052f1dc7 | 6638 | #ifdef CONFIG_RT_GROUP_SCHED |
182446d0 TH |
6639 | static int cpu_rt_runtime_write(struct cgroup_subsys_state *css, |
6640 | struct cftype *cft, s64 val) | |
6f505b16 | 6641 | { |
182446d0 | 6642 | return sched_group_set_rt_runtime(css_tg(css), val); |
6f505b16 PZ |
6643 | } |
6644 | ||
182446d0 TH |
6645 | static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css, |
6646 | struct cftype *cft) | |
6f505b16 | 6647 | { |
182446d0 | 6648 | return sched_group_rt_runtime(css_tg(css)); |
6f505b16 | 6649 | } |
d0b27fa7 | 6650 | |
182446d0 TH |
6651 | static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css, |
6652 | struct cftype *cftype, u64 rt_period_us) | |
d0b27fa7 | 6653 | { |
182446d0 | 6654 | return sched_group_set_rt_period(css_tg(css), rt_period_us); |
d0b27fa7 PZ |
6655 | } |
6656 | ||
182446d0 TH |
6657 | static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css, |
6658 | struct cftype *cft) | |
d0b27fa7 | 6659 | { |
182446d0 | 6660 | return sched_group_rt_period(css_tg(css)); |
d0b27fa7 | 6661 | } |
6d6bc0ad | 6662 | #endif /* CONFIG_RT_GROUP_SCHED */ |
6f505b16 | 6663 | |
fe5c7cc2 | 6664 | static struct cftype cpu_files[] = { |
052f1dc7 | 6665 | #ifdef CONFIG_FAIR_GROUP_SCHED |
fe5c7cc2 PM |
6666 | { |
6667 | .name = "shares", | |
f4c753b7 PM |
6668 | .read_u64 = cpu_shares_read_u64, |
6669 | .write_u64 = cpu_shares_write_u64, | |
fe5c7cc2 | 6670 | }, |
052f1dc7 | 6671 | #endif |
ab84d31e PT |
6672 | #ifdef CONFIG_CFS_BANDWIDTH |
6673 | { | |
6674 | .name = "cfs_quota_us", | |
6675 | .read_s64 = cpu_cfs_quota_read_s64, | |
6676 | .write_s64 = cpu_cfs_quota_write_s64, | |
6677 | }, | |
6678 | { | |
6679 | .name = "cfs_period_us", | |
6680 | .read_u64 = cpu_cfs_period_read_u64, | |
6681 | .write_u64 = cpu_cfs_period_write_u64, | |
6682 | }, | |
e8da1b18 NR |
6683 | { |
6684 | .name = "stat", | |
2da8ca82 | 6685 | .seq_show = cpu_stats_show, |
e8da1b18 | 6686 | }, |
ab84d31e | 6687 | #endif |
052f1dc7 | 6688 | #ifdef CONFIG_RT_GROUP_SCHED |
6f505b16 | 6689 | { |
9f0c1e56 | 6690 | .name = "rt_runtime_us", |
06ecb27c PM |
6691 | .read_s64 = cpu_rt_runtime_read, |
6692 | .write_s64 = cpu_rt_runtime_write, | |
6f505b16 | 6693 | }, |
d0b27fa7 PZ |
6694 | { |
6695 | .name = "rt_period_us", | |
f4c753b7 PM |
6696 | .read_u64 = cpu_rt_period_read_uint, |
6697 | .write_u64 = cpu_rt_period_write_uint, | |
d0b27fa7 | 6698 | }, |
052f1dc7 | 6699 | #endif |
d1ccc66d | 6700 | { } /* Terminate */ |
68318b8e SV |
6701 | }; |
6702 | ||
073219e9 | 6703 | struct cgroup_subsys cpu_cgrp_subsys = { |
92fb9748 | 6704 | .css_alloc = cpu_cgroup_css_alloc, |
96b77745 | 6705 | .css_online = cpu_cgroup_css_online, |
2f5177f0 | 6706 | .css_released = cpu_cgroup_css_released, |
92fb9748 | 6707 | .css_free = cpu_cgroup_css_free, |
eeb61e53 | 6708 | .fork = cpu_cgroup_fork, |
bb9d97b6 TH |
6709 | .can_attach = cpu_cgroup_can_attach, |
6710 | .attach = cpu_cgroup_attach, | |
5577964e | 6711 | .legacy_cftypes = cpu_files, |
b38e42e9 | 6712 | .early_init = true, |
68318b8e SV |
6713 | }; |
6714 | ||
052f1dc7 | 6715 | #endif /* CONFIG_CGROUP_SCHED */ |
d842de87 | 6716 | |
b637a328 PM |
6717 | void dump_cpu_task(int cpu) |
6718 | { | |
6719 | pr_info("Task dump for CPU %d:\n", cpu); | |
6720 | sched_show_task(cpu_curr(cpu)); | |
6721 | } | |
ed82b8a1 AK |
6722 | |
6723 | /* | |
6724 | * Nice levels are multiplicative, with a gentle 10% change for every | |
6725 | * nice level changed. I.e. when a CPU-bound task goes from nice 0 to | |
6726 | * nice 1, it will get ~10% less CPU time than another CPU-bound task | |
6727 | * that remained on nice 0. | |
6728 | * | |
6729 | * The "10% effect" is relative and cumulative: from _any_ nice level, | |
6730 | * if you go up 1 level, it's -10% CPU usage, if you go down 1 level | |
6731 | * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25. | |
6732 | * If a task goes up by ~10% and another task goes down by ~10% then | |
6733 | * the relative distance between them is ~25%.) | |
6734 | */ | |
6735 | const int sched_prio_to_weight[40] = { | |
6736 | /* -20 */ 88761, 71755, 56483, 46273, 36291, | |
6737 | /* -15 */ 29154, 23254, 18705, 14949, 11916, | |
6738 | /* -10 */ 9548, 7620, 6100, 4904, 3906, | |
6739 | /* -5 */ 3121, 2501, 1991, 1586, 1277, | |
6740 | /* 0 */ 1024, 820, 655, 526, 423, | |
6741 | /* 5 */ 335, 272, 215, 172, 137, | |
6742 | /* 10 */ 110, 87, 70, 56, 45, | |
6743 | /* 15 */ 36, 29, 23, 18, 15, | |
6744 | }; | |
6745 | ||
6746 | /* | |
6747 | * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated. | |
6748 | * | |
6749 | * In cases where the weight does not change often, we can use the | |
6750 | * precalculated inverse to speed up arithmetics by turning divisions | |
6751 | * into multiplications: | |
6752 | */ | |
6753 | const u32 sched_prio_to_wmult[40] = { | |
6754 | /* -20 */ 48388, 59856, 76040, 92818, 118348, | |
6755 | /* -15 */ 147320, 184698, 229616, 287308, 360437, | |
6756 | /* -10 */ 449829, 563644, 704093, 875809, 1099582, | |
6757 | /* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326, | |
6758 | /* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587, | |
6759 | /* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126, | |
6760 | /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, | |
6761 | /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, | |
6762 | }; |