Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Simple CPU accounting cgroup controller
4 : */
5 : #include "sched.h"
6 :
7 : #ifdef CONFIG_IRQ_TIME_ACCOUNTING
8 :
9 : /*
10 : * There are no locks covering percpu hardirq/softirq time.
11 : * They are only modified in vtime_account, on corresponding CPU
12 : * with interrupts disabled. So, writes are safe.
13 : * They are read and saved off onto struct rq in update_rq_clock().
14 : * This may result in other CPU reading this CPU's irq time and can
15 : * race with irq/vtime_account on this CPU. We would either get old
16 : * or new value with a side effect of accounting a slice of irq time to wrong
17 : * task when irq is in progress while we read rq->clock. That is a worthy
18 : * compromise in place of having locks on each irq in account_system_time.
19 : */
20 : DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
21 :
22 : static int sched_clock_irqtime;
23 :
24 : void enable_sched_clock_irqtime(void)
25 : {
26 : sched_clock_irqtime = 1;
27 : }
28 :
29 : void disable_sched_clock_irqtime(void)
30 : {
31 : sched_clock_irqtime = 0;
32 : }
33 :
34 : static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
35 : enum cpu_usage_stat idx)
36 : {
37 : u64 *cpustat = kcpustat_this_cpu->cpustat;
38 :
39 : u64_stats_update_begin(&irqtime->sync);
40 : cpustat[idx] += delta;
41 : irqtime->total += delta;
42 : irqtime->tick_delta += delta;
43 : u64_stats_update_end(&irqtime->sync);
44 : }
45 :
46 : /*
47 : * Called after incrementing preempt_count on {soft,}irq_enter
48 : * and before decrementing preempt_count on {soft,}irq_exit.
49 : */
50 : void irqtime_account_irq(struct task_struct *curr, unsigned int offset)
51 : {
52 : struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
53 : unsigned int pc;
54 : s64 delta;
55 : int cpu;
56 :
57 : if (!sched_clock_irqtime)
58 : return;
59 :
60 : cpu = smp_processor_id();
61 : delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
62 : irqtime->irq_start_time += delta;
63 : pc = preempt_count() - offset;
64 :
65 : /*
66 : * We do not account for softirq time from ksoftirqd here.
67 : * We want to continue accounting softirq time to ksoftirqd thread
68 : * in that case, so as not to confuse scheduler with a special task
69 : * that do not consume any time, but still wants to run.
70 : */
71 : if (pc & HARDIRQ_MASK)
72 : irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
73 : else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd())
74 : irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
75 : }
76 :
77 : static u64 irqtime_tick_accounted(u64 maxtime)
78 : {
79 : struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
80 : u64 delta;
81 :
82 : delta = min(irqtime->tick_delta, maxtime);
83 : irqtime->tick_delta -= delta;
84 :
85 : return delta;
86 : }
87 :
88 : #else /* CONFIG_IRQ_TIME_ACCOUNTING */
89 :
90 : #define sched_clock_irqtime (0)
91 :
92 : static u64 irqtime_tick_accounted(u64 dummy)
93 : {
94 : return 0;
95 : }
96 :
97 : #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
98 :
99 15235 : static inline void task_group_account_field(struct task_struct *p, int index,
100 : u64 tmp)
101 : {
102 : /*
103 : * Since all updates are sure to touch the root cgroup, we
104 : * get ourselves ahead and touch it first. If the root cgroup
105 : * is the only cgroup, then nothing else should be necessary.
106 : *
107 : */
108 15235 : __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
109 :
110 15235 : cgroup_account_cputime_field(p, index, tmp);
111 15421 : }
112 :
113 : /*
114 : * Account user CPU time to a process.
115 : * @p: the process that the CPU time gets accounted to
116 : * @cputime: the CPU time spent in user space since the last update
117 : */
118 604 : void account_user_time(struct task_struct *p, u64 cputime)
119 : {
120 604 : int index;
121 :
122 : /* Add user time to process. */
123 604 : p->utime += cputime;
124 604 : account_group_user_time(p, cputime);
125 :
126 605 : index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
127 :
128 : /* Add user time to cpustat. */
129 605 : task_group_account_field(p, index, cputime);
130 :
131 : /* Account for user time used */
132 604 : acct_account_cputime(p);
133 606 : }
134 :
135 : /*
136 : * Account guest CPU time to a process.
137 : * @p: the process that the CPU time gets accounted to
138 : * @cputime: the CPU time spent in virtual machine since the last update
139 : */
140 0 : void account_guest_time(struct task_struct *p, u64 cputime)
141 : {
142 0 : u64 *cpustat = kcpustat_this_cpu->cpustat;
143 :
144 : /* Add guest time to process. */
145 0 : p->utime += cputime;
146 0 : account_group_user_time(p, cputime);
147 0 : p->gtime += cputime;
148 :
149 : /* Add guest time to cpustat. */
150 0 : if (task_nice(p) > 0) {
151 0 : cpustat[CPUTIME_NICE] += cputime;
152 0 : cpustat[CPUTIME_GUEST_NICE] += cputime;
153 : } else {
154 0 : cpustat[CPUTIME_USER] += cputime;
155 0 : cpustat[CPUTIME_GUEST] += cputime;
156 : }
157 0 : }
158 :
159 : /*
160 : * Account system CPU time to a process and desired cpustat field
161 : * @p: the process that the CPU time gets accounted to
162 : * @cputime: the CPU time spent in kernel space since the last update
163 : * @index: pointer to cpustat field that has to be updated
164 : */
165 14470 : void account_system_index_time(struct task_struct *p,
166 : u64 cputime, enum cpu_usage_stat index)
167 : {
168 : /* Add system time to process. */
169 14470 : p->stime += cputime;
170 14470 : account_group_system_time(p, cputime);
171 :
172 : /* Add system time to cpustat. */
173 14785 : task_group_account_field(p, index, cputime);
174 :
175 : /* Account for system time used */
176 14824 : acct_account_cputime(p);
177 14852 : }
178 :
179 : /*
180 : * Account system CPU time to a process.
181 : * @p: the process that the CPU time gets accounted to
182 : * @hardirq_offset: the offset to subtract from hardirq_count()
183 : * @cputime: the CPU time spent in kernel space since the last update
184 : */
185 14540 : void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
186 : {
187 14540 : int index;
188 :
189 14540 : if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
190 0 : account_guest_time(p, cputime);
191 0 : return;
192 : }
193 :
194 14540 : if (hardirq_count() - hardirq_offset)
195 : index = CPUTIME_IRQ;
196 14651 : else if (in_serving_softirq())
197 : index = CPUTIME_SOFTIRQ;
198 : else
199 11966 : index = CPUTIME_SYSTEM;
200 :
201 14540 : account_system_index_time(p, cputime, index);
202 : }
203 :
204 : /*
205 : * Account for involuntary wait time.
206 : * @cputime: the CPU time spent in involuntary wait
207 : */
208 25652 : void account_steal_time(u64 cputime)
209 : {
210 0 : u64 *cpustat = kcpustat_this_cpu->cpustat;
211 :
212 25770 : cpustat[CPUTIME_STEAL] += cputime;
213 0 : }
214 :
215 : /*
216 : * Account for idle time.
217 : * @cputime: the CPU time spent in idle wait
218 : */
219 10370 : void account_idle_time(u64 cputime)
220 : {
221 10370 : u64 *cpustat = kcpustat_this_cpu->cpustat;
222 10372 : struct rq *rq = this_rq();
223 :
224 10418 : if (atomic_read(&rq->nr_iowait) > 0)
225 95 : cpustat[CPUTIME_IOWAIT] += cputime;
226 : else
227 10333 : cpustat[CPUTIME_IDLE] += cputime;
228 10428 : }
229 :
230 : /*
231 : * When a guest is interrupted for a longer amount of time, missed clock
232 : * ticks are not redelivered later. Due to that, this function may on
233 : * occasion account more time than the calling functions think elapsed.
234 : */
235 25286 : static __always_inline u64 steal_account_process_time(u64 maxtime)
236 : {
237 : #ifdef CONFIG_PARAVIRT
238 101787 : if (static_key_false(¶virt_steal_enabled)) {
239 25469 : u64 steal;
240 :
241 25469 : steal = paravirt_steal_clock(smp_processor_id());
242 25626 : steal -= this_rq()->prev_steal_time;
243 25652 : steal = min(steal, maxtime);
244 25652 : account_steal_time(steal);
245 25770 : this_rq()->prev_steal_time += steal;
246 :
247 695 : return steal;
248 : }
249 : #endif
250 : return 0;
251 : }
252 :
253 : /*
254 : * Account how much elapsed time was spent in steal, irq, or softirq time.
255 : */
256 : static inline u64 account_other_time(u64 max)
257 : {
258 : u64 accounted;
259 :
260 : lockdep_assert_irqs_disabled();
261 :
262 : accounted = steal_account_process_time(max);
263 :
264 : if (accounted < max)
265 : accounted += irqtime_tick_accounted(max - accounted);
266 :
267 : return accounted;
268 : }
269 :
270 : #ifdef CONFIG_64BIT
271 1045 : static inline u64 read_sum_exec_runtime(struct task_struct *t)
272 : {
273 1045 : return t->se.sum_exec_runtime;
274 : }
275 : #else
276 : static u64 read_sum_exec_runtime(struct task_struct *t)
277 : {
278 : u64 ns;
279 : struct rq_flags rf;
280 : struct rq *rq;
281 :
282 : rq = task_rq_lock(t, &rf);
283 : ns = t->se.sum_exec_runtime;
284 : task_rq_unlock(rq, t, &rf);
285 :
286 : return ns;
287 : }
288 : #endif
289 :
290 : /*
291 : * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
292 : * tasks (sum on group iteration) belonging to @tsk's group.
293 : */
294 1045 : void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
295 : {
296 1045 : struct signal_struct *sig = tsk->signal;
297 1045 : u64 utime, stime;
298 1045 : struct task_struct *t;
299 1045 : unsigned int seq, nextseq;
300 1045 : unsigned long flags;
301 :
302 : /*
303 : * Update current task runtime to account pending time since last
304 : * scheduler action or thread_group_cputime() call. This thread group
305 : * might have other running tasks on different CPUs, but updating
306 : * their runtime can affect syscall performance, so we skip account
307 : * those pending times and rely only on values updated on tick or
308 : * other scheduler action.
309 : */
310 1045 : if (same_thread_group(current, tsk))
311 49 : (void) task_sched_runtime(current);
312 :
313 1045 : rcu_read_lock();
314 : /* Attempt a lockless read on the first round. */
315 : nextseq = 0;
316 1045 : do {
317 1045 : seq = nextseq;
318 2090 : flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
319 1045 : times->utime = sig->utime;
320 1045 : times->stime = sig->stime;
321 1045 : times->sum_exec_runtime = sig->sum_sched_runtime;
322 :
323 2090 : for_each_thread(tsk, t) {
324 1045 : task_cputime(t, &utime, &stime);
325 1045 : times->utime += utime;
326 1045 : times->stime += stime;
327 1045 : times->sum_exec_runtime += read_sum_exec_runtime(t);
328 : }
329 : /* If lockless access failed, take the lock. */
330 1045 : nextseq = 1;
331 2090 : } while (need_seqretry(&sig->stats_lock, seq));
332 1045 : done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
333 1045 : rcu_read_unlock();
334 1045 : }
335 :
336 : #ifdef CONFIG_IRQ_TIME_ACCOUNTING
337 : /*
338 : * Account a tick to a process and cpustat
339 : * @p: the process that the CPU time gets accounted to
340 : * @user_tick: is the tick from userspace
341 : * @rq: the pointer to rq
342 : *
343 : * Tick demultiplexing follows the order
344 : * - pending hardirq update
345 : * - pending softirq update
346 : * - user_time
347 : * - idle_time
348 : * - system time
349 : * - check for guest_time
350 : * - else account as system_time
351 : *
352 : * Check for hardirq is done both for system and user time as there is
353 : * no timer going off while we are on hardirq and hence we may never get an
354 : * opportunity to update it solely in system time.
355 : * p->stime and friends are only updated on system time and not on irq
356 : * softirq as those do not count in task exec_runtime any more.
357 : */
358 : static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
359 : int ticks)
360 : {
361 : u64 other, cputime = TICK_NSEC * ticks;
362 :
363 : /*
364 : * When returning from idle, many ticks can get accounted at
365 : * once, including some ticks of steal, irq, and softirq time.
366 : * Subtract those ticks from the amount of time accounted to
367 : * idle, or potentially user or system time. Due to rounding,
368 : * other time can exceed ticks occasionally.
369 : */
370 : other = account_other_time(ULONG_MAX);
371 : if (other >= cputime)
372 : return;
373 :
374 : cputime -= other;
375 :
376 : if (this_cpu_ksoftirqd() == p) {
377 : /*
378 : * ksoftirqd time do not get accounted in cpu_softirq_time.
379 : * So, we have to handle it separately here.
380 : * Also, p->stime needs to be updated for ksoftirqd.
381 : */
382 : account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
383 : } else if (user_tick) {
384 : account_user_time(p, cputime);
385 : } else if (p == this_rq()->idle) {
386 : account_idle_time(cputime);
387 : } else if (p->flags & PF_VCPU) { /* System time or guest time */
388 : account_guest_time(p, cputime);
389 : } else {
390 : account_system_index_time(p, cputime, CPUTIME_SYSTEM);
391 : }
392 : }
393 :
394 : static void irqtime_account_idle_ticks(int ticks)
395 : {
396 : irqtime_account_process_tick(current, 0, ticks);
397 : }
398 : #else /* CONFIG_IRQ_TIME_ACCOUNTING */
399 : static inline void irqtime_account_idle_ticks(int ticks) { }
400 : static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
401 : int nr_ticks) { }
402 : #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
403 :
404 : /*
405 : * Use precise platform statistics if available:
406 : */
407 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
408 :
409 : # ifndef __ARCH_HAS_VTIME_TASK_SWITCH
410 : void vtime_task_switch(struct task_struct *prev)
411 : {
412 : if (is_idle_task(prev))
413 : vtime_account_idle(prev);
414 : else
415 : vtime_account_kernel(prev);
416 :
417 : vtime_flush(prev);
418 : arch_vtime_task_switch(prev);
419 : }
420 : # endif
421 :
422 : void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
423 : {
424 : unsigned int pc = preempt_count() - offset;
425 :
426 : if (pc & HARDIRQ_OFFSET) {
427 : vtime_account_hardirq(tsk);
428 : } else if (pc & SOFTIRQ_OFFSET) {
429 : vtime_account_softirq(tsk);
430 : } else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
431 : is_idle_task(tsk)) {
432 : vtime_account_idle(tsk);
433 : } else {
434 : vtime_account_kernel(tsk);
435 : }
436 : }
437 :
438 : void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
439 : u64 *ut, u64 *st)
440 : {
441 : *ut = curr->utime;
442 : *st = curr->stime;
443 : }
444 :
445 : void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
446 : {
447 : *ut = p->utime;
448 : *st = p->stime;
449 : }
450 : EXPORT_SYMBOL_GPL(task_cputime_adjusted);
451 :
452 : void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
453 : {
454 : struct task_cputime cputime;
455 :
456 : thread_group_cputime(p, &cputime);
457 :
458 : *ut = cputime.utime;
459 : *st = cputime.stime;
460 : }
461 :
462 : #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE: */
463 :
464 : /*
465 : * Account a single tick of CPU time.
466 : * @p: the process that the CPU time gets accounted to
467 : * @user_tick: indicates if the tick is a user or a system tick
468 : */
469 24591 : void account_process_tick(struct task_struct *p, int user_tick)
470 : {
471 24591 : u64 cputime, steal;
472 :
473 24591 : if (vtime_accounting_enabled_this_cpu())
474 : return;
475 :
476 24591 : if (sched_clock_irqtime) {
477 : irqtime_account_process_tick(p, user_tick, 1);
478 : return;
479 : }
480 :
481 24591 : cputime = TICK_NSEC;
482 24591 : steal = steal_account_process_time(ULONG_MAX);
483 :
484 25191 : if (steal >= cputime)
485 : return;
486 :
487 25146 : cputime -= steal;
488 :
489 25146 : if (user_tick)
490 606 : account_user_time(p, cputime);
491 24540 : else if ((p != this_rq()->idle) || (irq_count() != HARDIRQ_OFFSET))
492 14818 : account_system_time(p, HARDIRQ_OFFSET, cputime);
493 : else
494 9736 : account_idle_time(cputime);
495 : }
496 :
497 : /*
498 : * Account multiple ticks of idle time.
499 : * @ticks: number of stolen ticks
500 : */
501 695 : void account_idle_ticks(unsigned long ticks)
502 : {
503 695 : u64 cputime, steal;
504 :
505 695 : if (sched_clock_irqtime) {
506 : irqtime_account_idle_ticks(ticks);
507 : return;
508 : }
509 :
510 695 : cputime = ticks * TICK_NSEC;
511 695 : steal = steal_account_process_time(ULONG_MAX);
512 :
513 695 : if (steal >= cputime)
514 : return;
515 :
516 695 : cputime -= steal;
517 695 : account_idle_time(cputime);
518 : }
519 :
520 : /*
521 : * Adjust tick based cputime random precision against scheduler runtime
522 : * accounting.
523 : *
524 : * Tick based cputime accounting depend on random scheduling timeslices of a
525 : * task to be interrupted or not by the timer. Depending on these
526 : * circumstances, the number of these interrupts may be over or
527 : * under-optimistic, matching the real user and system cputime with a variable
528 : * precision.
529 : *
530 : * Fix this by scaling these tick based values against the total runtime
531 : * accounted by the CFS scheduler.
532 : *
533 : * This code provides the following guarantees:
534 : *
535 : * stime + utime == rtime
536 : * stime_i+1 >= stime_i, utime_i+1 >= utime_i
537 : *
538 : * Assuming that rtime_i+1 >= rtime_i.
539 : */
540 1045 : void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
541 : u64 *ut, u64 *st)
542 : {
543 1045 : u64 rtime, stime, utime;
544 1045 : unsigned long flags;
545 :
546 : /* Serialize concurrent callers such that we can honour our guarantees */
547 1045 : raw_spin_lock_irqsave(&prev->lock, flags);
548 1045 : rtime = curr->sum_exec_runtime;
549 :
550 : /*
551 : * This is possible under two circumstances:
552 : * - rtime isn't monotonic after all (a bug);
553 : * - we got reordered by the lock.
554 : *
555 : * In both cases this acts as a filter such that the rest of the code
556 : * can assume it is monotonic regardless of anything else.
557 : */
558 1045 : if (prev->stime + prev->utime >= rtime)
559 23 : goto out;
560 :
561 1022 : stime = curr->stime;
562 1022 : utime = curr->utime;
563 :
564 : /*
565 : * If either stime or utime are 0, assume all runtime is userspace.
566 : * Once a task gets some ticks, the monotonicy code at 'update:'
567 : * will ensure things converge to the observed ratio.
568 : */
569 1022 : if (stime == 0) {
570 44 : utime = rtime;
571 44 : goto update;
572 : }
573 :
574 978 : if (utime == 0) {
575 773 : stime = rtime;
576 773 : goto update;
577 : }
578 :
579 205 : stime = mul_u64_u64_div_u64(stime, rtime, stime + utime);
580 :
581 1022 : update:
582 : /*
583 : * Make sure stime doesn't go backwards; this preserves monotonicity
584 : * for utime because rtime is monotonic.
585 : *
586 : * utime_i+1 = rtime_i+1 - stime_i
587 : * = rtime_i+1 - (rtime_i - utime_i)
588 : * = (rtime_i+1 - rtime_i) + utime_i
589 : * >= utime_i
590 : */
591 1022 : if (stime < prev->stime)
592 : stime = prev->stime;
593 1022 : utime = rtime - stime;
594 :
595 : /*
596 : * Make sure utime doesn't go backwards; this still preserves
597 : * monotonicity for stime, analogous argument to above.
598 : */
599 1022 : if (utime < prev->utime) {
600 13 : utime = prev->utime;
601 13 : stime = rtime - utime;
602 : }
603 :
604 1022 : prev->stime = stime;
605 1022 : prev->utime = utime;
606 1045 : out:
607 1045 : *ut = prev->utime;
608 1045 : *st = prev->stime;
609 1045 : raw_spin_unlock_irqrestore(&prev->lock, flags);
610 1045 : }
611 :
612 0 : void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
613 : {
614 0 : struct task_cputime cputime = {
615 0 : .sum_exec_runtime = p->se.sum_exec_runtime,
616 : };
617 :
618 0 : task_cputime(p, &cputime.utime, &cputime.stime);
619 0 : cputime_adjust(&cputime, &p->prev_cputime, ut, st);
620 0 : }
621 : EXPORT_SYMBOL_GPL(task_cputime_adjusted);
622 :
623 1045 : void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
624 : {
625 1045 : struct task_cputime cputime;
626 :
627 1045 : thread_group_cputime(p, &cputime);
628 1045 : cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
629 1045 : }
630 : #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
631 :
632 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
633 : static u64 vtime_delta(struct vtime *vtime)
634 : {
635 : unsigned long long clock;
636 :
637 : clock = sched_clock();
638 : if (clock < vtime->starttime)
639 : return 0;
640 :
641 : return clock - vtime->starttime;
642 : }
643 :
644 : static u64 get_vtime_delta(struct vtime *vtime)
645 : {
646 : u64 delta = vtime_delta(vtime);
647 : u64 other;
648 :
649 : /*
650 : * Unlike tick based timing, vtime based timing never has lost
651 : * ticks, and no need for steal time accounting to make up for
652 : * lost ticks. Vtime accounts a rounded version of actual
653 : * elapsed time. Limit account_other_time to prevent rounding
654 : * errors from causing elapsed vtime to go negative.
655 : */
656 : other = account_other_time(delta);
657 : WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
658 : vtime->starttime += delta;
659 :
660 : return delta - other;
661 : }
662 :
663 : static void vtime_account_system(struct task_struct *tsk,
664 : struct vtime *vtime)
665 : {
666 : vtime->stime += get_vtime_delta(vtime);
667 : if (vtime->stime >= TICK_NSEC) {
668 : account_system_time(tsk, irq_count(), vtime->stime);
669 : vtime->stime = 0;
670 : }
671 : }
672 :
673 : static void vtime_account_guest(struct task_struct *tsk,
674 : struct vtime *vtime)
675 : {
676 : vtime->gtime += get_vtime_delta(vtime);
677 : if (vtime->gtime >= TICK_NSEC) {
678 : account_guest_time(tsk, vtime->gtime);
679 : vtime->gtime = 0;
680 : }
681 : }
682 :
683 : static void __vtime_account_kernel(struct task_struct *tsk,
684 : struct vtime *vtime)
685 : {
686 : /* We might have scheduled out from guest path */
687 : if (vtime->state == VTIME_GUEST)
688 : vtime_account_guest(tsk, vtime);
689 : else
690 : vtime_account_system(tsk, vtime);
691 : }
692 :
693 : void vtime_account_kernel(struct task_struct *tsk)
694 : {
695 : struct vtime *vtime = &tsk->vtime;
696 :
697 : if (!vtime_delta(vtime))
698 : return;
699 :
700 : write_seqcount_begin(&vtime->seqcount);
701 : __vtime_account_kernel(tsk, vtime);
702 : write_seqcount_end(&vtime->seqcount);
703 : }
704 :
705 : void vtime_user_enter(struct task_struct *tsk)
706 : {
707 : struct vtime *vtime = &tsk->vtime;
708 :
709 : write_seqcount_begin(&vtime->seqcount);
710 : vtime_account_system(tsk, vtime);
711 : vtime->state = VTIME_USER;
712 : write_seqcount_end(&vtime->seqcount);
713 : }
714 :
715 : void vtime_user_exit(struct task_struct *tsk)
716 : {
717 : struct vtime *vtime = &tsk->vtime;
718 :
719 : write_seqcount_begin(&vtime->seqcount);
720 : vtime->utime += get_vtime_delta(vtime);
721 : if (vtime->utime >= TICK_NSEC) {
722 : account_user_time(tsk, vtime->utime);
723 : vtime->utime = 0;
724 : }
725 : vtime->state = VTIME_SYS;
726 : write_seqcount_end(&vtime->seqcount);
727 : }
728 :
729 : void vtime_guest_enter(struct task_struct *tsk)
730 : {
731 : struct vtime *vtime = &tsk->vtime;
732 : /*
733 : * The flags must be updated under the lock with
734 : * the vtime_starttime flush and update.
735 : * That enforces a right ordering and update sequence
736 : * synchronization against the reader (task_gtime())
737 : * that can thus safely catch up with a tickless delta.
738 : */
739 : write_seqcount_begin(&vtime->seqcount);
740 : vtime_account_system(tsk, vtime);
741 : tsk->flags |= PF_VCPU;
742 : vtime->state = VTIME_GUEST;
743 : write_seqcount_end(&vtime->seqcount);
744 : }
745 : EXPORT_SYMBOL_GPL(vtime_guest_enter);
746 :
747 : void vtime_guest_exit(struct task_struct *tsk)
748 : {
749 : struct vtime *vtime = &tsk->vtime;
750 :
751 : write_seqcount_begin(&vtime->seqcount);
752 : vtime_account_guest(tsk, vtime);
753 : tsk->flags &= ~PF_VCPU;
754 : vtime->state = VTIME_SYS;
755 : write_seqcount_end(&vtime->seqcount);
756 : }
757 : EXPORT_SYMBOL_GPL(vtime_guest_exit);
758 :
759 : void vtime_account_idle(struct task_struct *tsk)
760 : {
761 : account_idle_time(get_vtime_delta(&tsk->vtime));
762 : }
763 :
764 : void vtime_task_switch_generic(struct task_struct *prev)
765 : {
766 : struct vtime *vtime = &prev->vtime;
767 :
768 : write_seqcount_begin(&vtime->seqcount);
769 : if (vtime->state == VTIME_IDLE)
770 : vtime_account_idle(prev);
771 : else
772 : __vtime_account_kernel(prev, vtime);
773 : vtime->state = VTIME_INACTIVE;
774 : vtime->cpu = -1;
775 : write_seqcount_end(&vtime->seqcount);
776 :
777 : vtime = ¤t->vtime;
778 :
779 : write_seqcount_begin(&vtime->seqcount);
780 : if (is_idle_task(current))
781 : vtime->state = VTIME_IDLE;
782 : else if (current->flags & PF_VCPU)
783 : vtime->state = VTIME_GUEST;
784 : else
785 : vtime->state = VTIME_SYS;
786 : vtime->starttime = sched_clock();
787 : vtime->cpu = smp_processor_id();
788 : write_seqcount_end(&vtime->seqcount);
789 : }
790 :
791 : void vtime_init_idle(struct task_struct *t, int cpu)
792 : {
793 : struct vtime *vtime = &t->vtime;
794 : unsigned long flags;
795 :
796 : local_irq_save(flags);
797 : write_seqcount_begin(&vtime->seqcount);
798 : vtime->state = VTIME_IDLE;
799 : vtime->starttime = sched_clock();
800 : vtime->cpu = cpu;
801 : write_seqcount_end(&vtime->seqcount);
802 : local_irq_restore(flags);
803 : }
804 :
805 : u64 task_gtime(struct task_struct *t)
806 : {
807 : struct vtime *vtime = &t->vtime;
808 : unsigned int seq;
809 : u64 gtime;
810 :
811 : if (!vtime_accounting_enabled())
812 : return t->gtime;
813 :
814 : do {
815 : seq = read_seqcount_begin(&vtime->seqcount);
816 :
817 : gtime = t->gtime;
818 : if (vtime->state == VTIME_GUEST)
819 : gtime += vtime->gtime + vtime_delta(vtime);
820 :
821 : } while (read_seqcount_retry(&vtime->seqcount, seq));
822 :
823 : return gtime;
824 : }
825 :
826 : /*
827 : * Fetch cputime raw values from fields of task_struct and
828 : * add up the pending nohz execution time since the last
829 : * cputime snapshot.
830 : */
831 : void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
832 : {
833 : struct vtime *vtime = &t->vtime;
834 : unsigned int seq;
835 : u64 delta;
836 :
837 : if (!vtime_accounting_enabled()) {
838 : *utime = t->utime;
839 : *stime = t->stime;
840 : return;
841 : }
842 :
843 : do {
844 : seq = read_seqcount_begin(&vtime->seqcount);
845 :
846 : *utime = t->utime;
847 : *stime = t->stime;
848 :
849 : /* Task is sleeping or idle, nothing to add */
850 : if (vtime->state < VTIME_SYS)
851 : continue;
852 :
853 : delta = vtime_delta(vtime);
854 :
855 : /*
856 : * Task runs either in user (including guest) or kernel space,
857 : * add pending nohz time to the right place.
858 : */
859 : if (vtime->state == VTIME_SYS)
860 : *stime += vtime->stime + delta;
861 : else
862 : *utime += vtime->utime + delta;
863 : } while (read_seqcount_retry(&vtime->seqcount, seq));
864 : }
865 :
866 : static int vtime_state_fetch(struct vtime *vtime, int cpu)
867 : {
868 : int state = READ_ONCE(vtime->state);
869 :
870 : /*
871 : * We raced against a context switch, fetch the
872 : * kcpustat task again.
873 : */
874 : if (vtime->cpu != cpu && vtime->cpu != -1)
875 : return -EAGAIN;
876 :
877 : /*
878 : * Two possible things here:
879 : * 1) We are seeing the scheduling out task (prev) or any past one.
880 : * 2) We are seeing the scheduling in task (next) but it hasn't
881 : * passed though vtime_task_switch() yet so the pending
882 : * cputime of the prev task may not be flushed yet.
883 : *
884 : * Case 1) is ok but 2) is not. So wait for a safe VTIME state.
885 : */
886 : if (state == VTIME_INACTIVE)
887 : return -EAGAIN;
888 :
889 : return state;
890 : }
891 :
892 : static u64 kcpustat_user_vtime(struct vtime *vtime)
893 : {
894 : if (vtime->state == VTIME_USER)
895 : return vtime->utime + vtime_delta(vtime);
896 : else if (vtime->state == VTIME_GUEST)
897 : return vtime->gtime + vtime_delta(vtime);
898 : return 0;
899 : }
900 :
901 : static int kcpustat_field_vtime(u64 *cpustat,
902 : struct task_struct *tsk,
903 : enum cpu_usage_stat usage,
904 : int cpu, u64 *val)
905 : {
906 : struct vtime *vtime = &tsk->vtime;
907 : unsigned int seq;
908 :
909 : do {
910 : int state;
911 :
912 : seq = read_seqcount_begin(&vtime->seqcount);
913 :
914 : state = vtime_state_fetch(vtime, cpu);
915 : if (state < 0)
916 : return state;
917 :
918 : *val = cpustat[usage];
919 :
920 : /*
921 : * Nice VS unnice cputime accounting may be inaccurate if
922 : * the nice value has changed since the last vtime update.
923 : * But proper fix would involve interrupting target on nice
924 : * updates which is a no go on nohz_full (although the scheduler
925 : * may still interrupt the target if rescheduling is needed...)
926 : */
927 : switch (usage) {
928 : case CPUTIME_SYSTEM:
929 : if (state == VTIME_SYS)
930 : *val += vtime->stime + vtime_delta(vtime);
931 : break;
932 : case CPUTIME_USER:
933 : if (task_nice(tsk) <= 0)
934 : *val += kcpustat_user_vtime(vtime);
935 : break;
936 : case CPUTIME_NICE:
937 : if (task_nice(tsk) > 0)
938 : *val += kcpustat_user_vtime(vtime);
939 : break;
940 : case CPUTIME_GUEST:
941 : if (state == VTIME_GUEST && task_nice(tsk) <= 0)
942 : *val += vtime->gtime + vtime_delta(vtime);
943 : break;
944 : case CPUTIME_GUEST_NICE:
945 : if (state == VTIME_GUEST && task_nice(tsk) > 0)
946 : *val += vtime->gtime + vtime_delta(vtime);
947 : break;
948 : default:
949 : break;
950 : }
951 : } while (read_seqcount_retry(&vtime->seqcount, seq));
952 :
953 : return 0;
954 : }
955 :
956 : u64 kcpustat_field(struct kernel_cpustat *kcpustat,
957 : enum cpu_usage_stat usage, int cpu)
958 : {
959 : u64 *cpustat = kcpustat->cpustat;
960 : u64 val = cpustat[usage];
961 : struct rq *rq;
962 : int err;
963 :
964 : if (!vtime_accounting_enabled_cpu(cpu))
965 : return val;
966 :
967 : rq = cpu_rq(cpu);
968 :
969 : for (;;) {
970 : struct task_struct *curr;
971 :
972 : rcu_read_lock();
973 : curr = rcu_dereference(rq->curr);
974 : if (WARN_ON_ONCE(!curr)) {
975 : rcu_read_unlock();
976 : return cpustat[usage];
977 : }
978 :
979 : err = kcpustat_field_vtime(cpustat, curr, usage, cpu, &val);
980 : rcu_read_unlock();
981 :
982 : if (!err)
983 : return val;
984 :
985 : cpu_relax();
986 : }
987 : }
988 : EXPORT_SYMBOL_GPL(kcpustat_field);
989 :
990 : static int kcpustat_cpu_fetch_vtime(struct kernel_cpustat *dst,
991 : const struct kernel_cpustat *src,
992 : struct task_struct *tsk, int cpu)
993 : {
994 : struct vtime *vtime = &tsk->vtime;
995 : unsigned int seq;
996 :
997 : do {
998 : u64 *cpustat;
999 : u64 delta;
1000 : int state;
1001 :
1002 : seq = read_seqcount_begin(&vtime->seqcount);
1003 :
1004 : state = vtime_state_fetch(vtime, cpu);
1005 : if (state < 0)
1006 : return state;
1007 :
1008 : *dst = *src;
1009 : cpustat = dst->cpustat;
1010 :
1011 : /* Task is sleeping, dead or idle, nothing to add */
1012 : if (state < VTIME_SYS)
1013 : continue;
1014 :
1015 : delta = vtime_delta(vtime);
1016 :
1017 : /*
1018 : * Task runs either in user (including guest) or kernel space,
1019 : * add pending nohz time to the right place.
1020 : */
1021 : if (state == VTIME_SYS) {
1022 : cpustat[CPUTIME_SYSTEM] += vtime->stime + delta;
1023 : } else if (state == VTIME_USER) {
1024 : if (task_nice(tsk) > 0)
1025 : cpustat[CPUTIME_NICE] += vtime->utime + delta;
1026 : else
1027 : cpustat[CPUTIME_USER] += vtime->utime + delta;
1028 : } else {
1029 : WARN_ON_ONCE(state != VTIME_GUEST);
1030 : if (task_nice(tsk) > 0) {
1031 : cpustat[CPUTIME_GUEST_NICE] += vtime->gtime + delta;
1032 : cpustat[CPUTIME_NICE] += vtime->gtime + delta;
1033 : } else {
1034 : cpustat[CPUTIME_GUEST] += vtime->gtime + delta;
1035 : cpustat[CPUTIME_USER] += vtime->gtime + delta;
1036 : }
1037 : }
1038 : } while (read_seqcount_retry(&vtime->seqcount, seq));
1039 :
1040 : return 0;
1041 : }
1042 :
1043 : void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu)
1044 : {
1045 : const struct kernel_cpustat *src = &kcpustat_cpu(cpu);
1046 : struct rq *rq;
1047 : int err;
1048 :
1049 : if (!vtime_accounting_enabled_cpu(cpu)) {
1050 : *dst = *src;
1051 : return;
1052 : }
1053 :
1054 : rq = cpu_rq(cpu);
1055 :
1056 : for (;;) {
1057 : struct task_struct *curr;
1058 :
1059 : rcu_read_lock();
1060 : curr = rcu_dereference(rq->curr);
1061 : if (WARN_ON_ONCE(!curr)) {
1062 : rcu_read_unlock();
1063 : *dst = *src;
1064 : return;
1065 : }
1066 :
1067 : err = kcpustat_cpu_fetch_vtime(dst, src, curr, cpu);
1068 : rcu_read_unlock();
1069 :
1070 : if (!err)
1071 : return;
1072 :
1073 : cpu_relax();
1074 : }
1075 : }
1076 : EXPORT_SYMBOL_GPL(kcpustat_cpu_fetch);
1077 :
1078 : #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
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