Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Simple CPU accounting cgroup controller
4 : */
5 :
6 : #ifdef CONFIG_IRQ_TIME_ACCOUNTING
7 :
8 : /*
9 : * There are no locks covering percpu hardirq/softirq time.
10 : * They are only modified in vtime_account, on corresponding CPU
11 : * with interrupts disabled. So, writes are safe.
12 : * They are read and saved off onto struct rq in update_rq_clock().
13 : * This may result in other CPU reading this CPU's irq time and can
14 : * race with irq/vtime_account on this CPU. We would either get old
15 : * or new value with a side effect of accounting a slice of irq time to wrong
16 : * task when irq is in progress while we read rq->clock. That is a worthy
17 : * compromise in place of having locks on each irq in account_system_time.
18 : */
19 : DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
20 :
21 : static int sched_clock_irqtime;
22 :
23 : void enable_sched_clock_irqtime(void)
24 : {
25 : sched_clock_irqtime = 1;
26 : }
27 :
28 : void disable_sched_clock_irqtime(void)
29 : {
30 : sched_clock_irqtime = 0;
31 : }
32 :
33 : static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
34 : enum cpu_usage_stat idx)
35 : {
36 : u64 *cpustat = kcpustat_this_cpu->cpustat;
37 :
38 : u64_stats_update_begin(&irqtime->sync);
39 : cpustat[idx] += delta;
40 : irqtime->total += delta;
41 : irqtime->tick_delta += delta;
42 : u64_stats_update_end(&irqtime->sync);
43 : }
44 :
45 : /*
46 : * Called after incrementing preempt_count on {soft,}irq_enter
47 : * and before decrementing preempt_count on {soft,}irq_exit.
48 : */
49 : void irqtime_account_irq(struct task_struct *curr, unsigned int offset)
50 : {
51 : struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
52 : unsigned int pc;
53 : s64 delta;
54 : int cpu;
55 :
56 : if (!sched_clock_irqtime)
57 : return;
58 :
59 : cpu = smp_processor_id();
60 : delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
61 : irqtime->irq_start_time += delta;
62 : pc = irq_count() - offset;
63 :
64 : /*
65 : * We do not account for softirq time from ksoftirqd here.
66 : * We want to continue accounting softirq time to ksoftirqd thread
67 : * in that case, so as not to confuse scheduler with a special task
68 : * that do not consume any time, but still wants to run.
69 : */
70 : if (pc & HARDIRQ_MASK)
71 : irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
72 : else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd())
73 : irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
74 : }
75 :
76 : static u64 irqtime_tick_accounted(u64 maxtime)
77 : {
78 : struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
79 : u64 delta;
80 :
81 : delta = min(irqtime->tick_delta, maxtime);
82 : irqtime->tick_delta -= delta;
83 :
84 : return delta;
85 : }
86 :
87 : #else /* CONFIG_IRQ_TIME_ACCOUNTING */
88 :
89 : #define sched_clock_irqtime (0)
90 :
91 : static u64 irqtime_tick_accounted(u64 dummy)
92 : {
93 : return 0;
94 : }
95 :
96 : #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
97 :
98 : static inline void task_group_account_field(struct task_struct *p, int index,
99 : u64 tmp)
100 : {
101 : /*
102 : * Since all updates are sure to touch the root cgroup, we
103 : * get ourselves ahead and touch it first. If the root cgroup
104 : * is the only cgroup, then nothing else should be necessary.
105 : *
106 : */
107 12 : __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
108 :
109 12 : cgroup_account_cputime_field(p, index, tmp);
110 : }
111 :
112 : /*
113 : * Account user CPU time to a process.
114 : * @p: the process that the CPU time gets accounted to
115 : * @cputime: the CPU time spent in user space since the last update
116 : */
117 0 : void account_user_time(struct task_struct *p, u64 cputime)
118 : {
119 : int index;
120 :
121 : /* Add user time to process. */
122 12 : p->utime += cputime;
123 12 : account_group_user_time(p, cputime);
124 :
125 24 : index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
126 :
127 : /* Add user time to cpustat. */
128 24 : task_group_account_field(p, index, cputime);
129 :
130 : /* Account for user time used */
131 12 : acct_account_cputime(p);
132 0 : }
133 :
134 : /*
135 : * Account guest CPU time to a process.
136 : * @p: the process that the CPU time gets accounted to
137 : * @cputime: the CPU time spent in virtual machine since the last update
138 : */
139 0 : void account_guest_time(struct task_struct *p, u64 cputime)
140 : {
141 0 : u64 *cpustat = kcpustat_this_cpu->cpustat;
142 :
143 : /* Add guest time to process. */
144 0 : p->utime += cputime;
145 0 : account_group_user_time(p, cputime);
146 0 : p->gtime += cputime;
147 :
148 : /* Add guest time to cpustat. */
149 0 : if (task_nice(p) > 0) {
150 0 : task_group_account_field(p, CPUTIME_NICE, cputime);
151 0 : cpustat[CPUTIME_GUEST_NICE] += cputime;
152 : } else {
153 0 : task_group_account_field(p, CPUTIME_USER, cputime);
154 0 : cpustat[CPUTIME_GUEST] += cputime;
155 : }
156 0 : }
157 :
158 : /*
159 : * Account system CPU time to a process and desired cpustat field
160 : * @p: the process that the CPU time gets accounted to
161 : * @cputime: the CPU time spent in kernel space since the last update
162 : * @index: pointer to cpustat field that has to be updated
163 : */
164 0 : void account_system_index_time(struct task_struct *p,
165 : u64 cputime, enum cpu_usage_stat index)
166 : {
167 : /* Add system time to process. */
168 0 : p->stime += cputime;
169 0 : account_group_system_time(p, cputime);
170 :
171 : /* Add system time to cpustat. */
172 0 : task_group_account_field(p, index, cputime);
173 :
174 : /* Account for system time used */
175 0 : acct_account_cputime(p);
176 0 : }
177 :
178 : /*
179 : * Account system CPU time to a process.
180 : * @p: the process that the CPU time gets accounted to
181 : * @hardirq_offset: the offset to subtract from hardirq_count()
182 : * @cputime: the CPU time spent in kernel space since the last update
183 : */
184 0 : void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
185 : {
186 : int index;
187 :
188 0 : if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
189 0 : account_guest_time(p, cputime);
190 0 : return;
191 : }
192 :
193 0 : if (hardirq_count() - hardirq_offset)
194 : index = CPUTIME_IRQ;
195 0 : else if (in_serving_softirq())
196 : index = CPUTIME_SOFTIRQ;
197 : else
198 0 : index = CPUTIME_SYSTEM;
199 :
200 0 : account_system_index_time(p, cputime, index);
201 : }
202 :
203 : /*
204 : * Account for involuntary wait time.
205 : * @cputime: the CPU time spent in involuntary wait
206 : */
207 0 : void account_steal_time(u64 cputime)
208 : {
209 0 : u64 *cpustat = kcpustat_this_cpu->cpustat;
210 :
211 0 : cpustat[CPUTIME_STEAL] += cputime;
212 0 : }
213 :
214 : /*
215 : * Account for idle time.
216 : * @cputime: the CPU time spent in idle wait
217 : */
218 0 : void account_idle_time(u64 cputime)
219 : {
220 1 : u64 *cpustat = kcpustat_this_cpu->cpustat;
221 1 : struct rq *rq = this_rq();
222 :
223 2 : if (atomic_read(&rq->nr_iowait) > 0)
224 0 : cpustat[CPUTIME_IOWAIT] += cputime;
225 : else
226 1 : cpustat[CPUTIME_IDLE] += cputime;
227 0 : }
228 :
229 : /*
230 : * When a guest is interrupted for a longer amount of time, missed clock
231 : * ticks are not redelivered later. Due to that, this function may on
232 : * occasion account more time than the calling functions think elapsed.
233 : */
234 : static __always_inline u64 steal_account_process_time(u64 maxtime)
235 : {
236 : #ifdef CONFIG_PARAVIRT
237 : if (static_key_false(¶virt_steal_enabled)) {
238 : u64 steal;
239 :
240 : steal = paravirt_steal_clock(smp_processor_id());
241 : steal -= this_rq()->prev_steal_time;
242 : steal = min(steal, maxtime);
243 : account_steal_time(steal);
244 : this_rq()->prev_steal_time += steal;
245 :
246 : return steal;
247 : }
248 : #endif
249 : return 0;
250 : }
251 :
252 : /*
253 : * Account how much elapsed time was spent in steal, irq, or softirq time.
254 : */
255 : static inline u64 account_other_time(u64 max)
256 : {
257 : u64 accounted;
258 :
259 : lockdep_assert_irqs_disabled();
260 :
261 : accounted = steal_account_process_time(max);
262 :
263 : if (accounted < max)
264 : accounted += irqtime_tick_accounted(max - accounted);
265 :
266 : return accounted;
267 : }
268 :
269 : #ifdef CONFIG_64BIT
270 : static inline u64 read_sum_exec_runtime(struct task_struct *t)
271 : {
272 : return t->se.sum_exec_runtime;
273 : }
274 : #else
275 : static u64 read_sum_exec_runtime(struct task_struct *t)
276 : {
277 : u64 ns;
278 : struct rq_flags rf;
279 : struct rq *rq;
280 :
281 : rq = task_rq_lock(t, &rf);
282 : ns = t->se.sum_exec_runtime;
283 : task_rq_unlock(rq, t, &rf);
284 :
285 : return ns;
286 : }
287 : #endif
288 :
289 : /*
290 : * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
291 : * tasks (sum on group iteration) belonging to @tsk's group.
292 : */
293 0 : void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
294 : {
295 0 : struct signal_struct *sig = tsk->signal;
296 : u64 utime, stime;
297 : struct task_struct *t;
298 : unsigned int seq, nextseq;
299 : unsigned long flags;
300 :
301 : /*
302 : * Update current task runtime to account pending time since last
303 : * scheduler action or thread_group_cputime() call. This thread group
304 : * might have other running tasks on different CPUs, but updating
305 : * their runtime can affect syscall performance, so we skip account
306 : * those pending times and rely only on values updated on tick or
307 : * other scheduler action.
308 : */
309 0 : if (same_thread_group(current, tsk))
310 0 : (void) task_sched_runtime(current);
311 :
312 : rcu_read_lock();
313 : /* Attempt a lockless read on the first round. */
314 0 : nextseq = 0;
315 : do {
316 0 : seq = nextseq;
317 0 : flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
318 0 : times->utime = sig->utime;
319 0 : times->stime = sig->stime;
320 0 : times->sum_exec_runtime = sig->sum_sched_runtime;
321 :
322 0 : for_each_thread(tsk, t) {
323 0 : task_cputime(t, &utime, &stime);
324 0 : times->utime += utime;
325 0 : times->stime += stime;
326 0 : times->sum_exec_runtime += read_sum_exec_runtime(t);
327 : }
328 : /* If lockless access failed, take the lock. */
329 0 : nextseq = 1;
330 0 : } while (need_seqretry(&sig->stats_lock, seq));
331 0 : done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
332 : rcu_read_unlock();
333 0 : }
334 :
335 : #ifdef CONFIG_IRQ_TIME_ACCOUNTING
336 : /*
337 : * Account a tick to a process and cpustat
338 : * @p: the process that the CPU time gets accounted to
339 : * @user_tick: is the tick from userspace
340 : * @rq: the pointer to rq
341 : *
342 : * Tick demultiplexing follows the order
343 : * - pending hardirq update
344 : * - pending softirq update
345 : * - user_time
346 : * - idle_time
347 : * - system time
348 : * - check for guest_time
349 : * - else account as system_time
350 : *
351 : * Check for hardirq is done both for system and user time as there is
352 : * no timer going off while we are on hardirq and hence we may never get an
353 : * opportunity to update it solely in system time.
354 : * p->stime and friends are only updated on system time and not on irq
355 : * softirq as those do not count in task exec_runtime any more.
356 : */
357 : static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
358 : int ticks)
359 : {
360 : u64 other, cputime = TICK_NSEC * ticks;
361 :
362 : /*
363 : * When returning from idle, many ticks can get accounted at
364 : * once, including some ticks of steal, irq, and softirq time.
365 : * Subtract those ticks from the amount of time accounted to
366 : * idle, or potentially user or system time. Due to rounding,
367 : * other time can exceed ticks occasionally.
368 : */
369 : other = account_other_time(ULONG_MAX);
370 : if (other >= cputime)
371 : return;
372 :
373 : cputime -= other;
374 :
375 : if (this_cpu_ksoftirqd() == p) {
376 : /*
377 : * ksoftirqd time do not get accounted in cpu_softirq_time.
378 : * So, we have to handle it separately here.
379 : * Also, p->stime needs to be updated for ksoftirqd.
380 : */
381 : account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
382 : } else if (user_tick) {
383 : account_user_time(p, cputime);
384 : } else if (p == this_rq()->idle) {
385 : account_idle_time(cputime);
386 : } else if (p->flags & PF_VCPU) { /* System time or guest time */
387 : account_guest_time(p, cputime);
388 : } else {
389 : account_system_index_time(p, cputime, CPUTIME_SYSTEM);
390 : }
391 : }
392 :
393 : static void irqtime_account_idle_ticks(int ticks)
394 : {
395 : irqtime_account_process_tick(current, 0, ticks);
396 : }
397 : #else /* CONFIG_IRQ_TIME_ACCOUNTING */
398 : static inline void irqtime_account_idle_ticks(int ticks) { }
399 : static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
400 : int nr_ticks) { }
401 : #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
402 :
403 : /*
404 : * Use precise platform statistics if available:
405 : */
406 : #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
407 :
408 : # ifndef __ARCH_HAS_VTIME_TASK_SWITCH
409 : void vtime_task_switch(struct task_struct *prev)
410 : {
411 : if (is_idle_task(prev))
412 : vtime_account_idle(prev);
413 : else
414 : vtime_account_kernel(prev);
415 :
416 : vtime_flush(prev);
417 : arch_vtime_task_switch(prev);
418 : }
419 : # endif
420 :
421 : void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
422 : {
423 : unsigned int pc = irq_count() - offset;
424 :
425 : if (pc & HARDIRQ_OFFSET) {
426 : vtime_account_hardirq(tsk);
427 : } else if (pc & SOFTIRQ_OFFSET) {
428 : vtime_account_softirq(tsk);
429 : } else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
430 : is_idle_task(tsk)) {
431 : vtime_account_idle(tsk);
432 : } else {
433 : vtime_account_kernel(tsk);
434 : }
435 : }
436 :
437 : void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
438 : u64 *ut, u64 *st)
439 : {
440 : *ut = curr->utime;
441 : *st = curr->stime;
442 : }
443 :
444 : void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
445 : {
446 : *ut = p->utime;
447 : *st = p->stime;
448 : }
449 : EXPORT_SYMBOL_GPL(task_cputime_adjusted);
450 :
451 : void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
452 : {
453 : struct task_cputime cputime;
454 :
455 : thread_group_cputime(p, &cputime);
456 :
457 : *ut = cputime.utime;
458 : *st = cputime.stime;
459 : }
460 :
461 : #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE: */
462 :
463 : /*
464 : * Account a single tick of CPU time.
465 : * @p: the process that the CPU time gets accounted to
466 : * @user_tick: indicates if the tick is a user or a system tick
467 : */
468 13 : void account_process_tick(struct task_struct *p, int user_tick)
469 : {
470 : u64 cputime, steal;
471 :
472 : if (vtime_accounting_enabled_this_cpu())
473 : return;
474 :
475 : if (sched_clock_irqtime) {
476 : irqtime_account_process_tick(p, user_tick, 1);
477 : return;
478 : }
479 :
480 13 : cputime = TICK_NSEC;
481 13 : steal = steal_account_process_time(ULONG_MAX);
482 :
483 : if (steal >= cputime)
484 : return;
485 :
486 13 : cputime -= steal;
487 :
488 13 : if (user_tick)
489 : account_user_time(p, cputime);
490 2 : else if ((p != this_rq()->idle) || (irq_count() != HARDIRQ_OFFSET))
491 0 : account_system_time(p, HARDIRQ_OFFSET, cputime);
492 : else
493 : account_idle_time(cputime);
494 : }
495 :
496 : /*
497 : * Account multiple ticks of idle time.
498 : * @ticks: number of stolen ticks
499 : */
500 0 : void account_idle_ticks(unsigned long ticks)
501 : {
502 : u64 cputime, steal;
503 :
504 : if (sched_clock_irqtime) {
505 : irqtime_account_idle_ticks(ticks);
506 : return;
507 : }
508 :
509 0 : cputime = ticks * TICK_NSEC;
510 0 : steal = steal_account_process_time(ULONG_MAX);
511 :
512 0 : if (steal >= cputime)
513 : return;
514 :
515 0 : cputime -= steal;
516 : account_idle_time(cputime);
517 : }
518 :
519 : /*
520 : * Adjust tick based cputime random precision against scheduler runtime
521 : * accounting.
522 : *
523 : * Tick based cputime accounting depend on random scheduling timeslices of a
524 : * task to be interrupted or not by the timer. Depending on these
525 : * circumstances, the number of these interrupts may be over or
526 : * under-optimistic, matching the real user and system cputime with a variable
527 : * precision.
528 : *
529 : * Fix this by scaling these tick based values against the total runtime
530 : * accounted by the CFS scheduler.
531 : *
532 : * This code provides the following guarantees:
533 : *
534 : * stime + utime == rtime
535 : * stime_i+1 >= stime_i, utime_i+1 >= utime_i
536 : *
537 : * Assuming that rtime_i+1 >= rtime_i.
538 : */
539 0 : void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
540 : u64 *ut, u64 *st)
541 : {
542 : u64 rtime, stime, utime;
543 : unsigned long flags;
544 :
545 : /* Serialize concurrent callers such that we can honour our guarantees */
546 0 : raw_spin_lock_irqsave(&prev->lock, flags);
547 0 : rtime = curr->sum_exec_runtime;
548 :
549 : /*
550 : * This is possible under two circumstances:
551 : * - rtime isn't monotonic after all (a bug);
552 : * - we got reordered by the lock.
553 : *
554 : * In both cases this acts as a filter such that the rest of the code
555 : * can assume it is monotonic regardless of anything else.
556 : */
557 0 : if (prev->stime + prev->utime >= rtime)
558 : goto out;
559 :
560 0 : stime = curr->stime;
561 0 : utime = curr->utime;
562 :
563 : /*
564 : * If either stime or utime are 0, assume all runtime is userspace.
565 : * Once a task gets some ticks, the monotonicity code at 'update:'
566 : * will ensure things converge to the observed ratio.
567 : */
568 0 : if (stime == 0) {
569 : utime = rtime;
570 : goto update;
571 : }
572 :
573 0 : if (utime == 0) {
574 : stime = rtime;
575 : goto update;
576 : }
577 :
578 0 : stime = mul_u64_u64_div_u64(stime, rtime, stime + utime);
579 :
580 : update:
581 : /*
582 : * Make sure stime doesn't go backwards; this preserves monotonicity
583 : * for utime because rtime is monotonic.
584 : *
585 : * utime_i+1 = rtime_i+1 - stime_i
586 : * = rtime_i+1 - (rtime_i - utime_i)
587 : * = (rtime_i+1 - rtime_i) + utime_i
588 : * >= utime_i
589 : */
590 0 : if (stime < prev->stime)
591 0 : stime = prev->stime;
592 0 : utime = rtime - stime;
593 :
594 : /*
595 : * Make sure utime doesn't go backwards; this still preserves
596 : * monotonicity for stime, analogous argument to above.
597 : */
598 0 : if (utime < prev->utime) {
599 0 : utime = prev->utime;
600 0 : stime = rtime - utime;
601 : }
602 :
603 0 : prev->stime = stime;
604 0 : prev->utime = utime;
605 : out:
606 0 : *ut = prev->utime;
607 0 : *st = prev->stime;
608 0 : raw_spin_unlock_irqrestore(&prev->lock, flags);
609 0 : }
610 :
611 0 : void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
612 : {
613 0 : struct task_cputime cputime = {
614 0 : .sum_exec_runtime = p->se.sum_exec_runtime,
615 : };
616 :
617 0 : if (task_cputime(p, &cputime.utime, &cputime.stime))
618 : cputime.sum_exec_runtime = task_sched_runtime(p);
619 0 : cputime_adjust(&cputime, &p->prev_cputime, ut, st);
620 0 : }
621 : EXPORT_SYMBOL_GPL(task_cputime_adjusted);
622 :
623 0 : void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
624 : {
625 : struct task_cputime cputime;
626 :
627 0 : thread_group_cputime(p, &cputime);
628 0 : cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
629 0 : }
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 : bool 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 : int ret;
837 :
838 : if (!vtime_accounting_enabled()) {
839 : *utime = t->utime;
840 : *stime = t->stime;
841 : return false;
842 : }
843 :
844 : do {
845 : ret = false;
846 : seq = read_seqcount_begin(&vtime->seqcount);
847 :
848 : *utime = t->utime;
849 : *stime = t->stime;
850 :
851 : /* Task is sleeping or idle, nothing to add */
852 : if (vtime->state < VTIME_SYS)
853 : continue;
854 :
855 : ret = true;
856 : delta = vtime_delta(vtime);
857 :
858 : /*
859 : * Task runs either in user (including guest) or kernel space,
860 : * add pending nohz time to the right place.
861 : */
862 : if (vtime->state == VTIME_SYS)
863 : *stime += vtime->stime + delta;
864 : else
865 : *utime += vtime->utime + delta;
866 : } while (read_seqcount_retry(&vtime->seqcount, seq));
867 :
868 : return ret;
869 : }
870 :
871 : static int vtime_state_fetch(struct vtime *vtime, int cpu)
872 : {
873 : int state = READ_ONCE(vtime->state);
874 :
875 : /*
876 : * We raced against a context switch, fetch the
877 : * kcpustat task again.
878 : */
879 : if (vtime->cpu != cpu && vtime->cpu != -1)
880 : return -EAGAIN;
881 :
882 : /*
883 : * Two possible things here:
884 : * 1) We are seeing the scheduling out task (prev) or any past one.
885 : * 2) We are seeing the scheduling in task (next) but it hasn't
886 : * passed though vtime_task_switch() yet so the pending
887 : * cputime of the prev task may not be flushed yet.
888 : *
889 : * Case 1) is ok but 2) is not. So wait for a safe VTIME state.
890 : */
891 : if (state == VTIME_INACTIVE)
892 : return -EAGAIN;
893 :
894 : return state;
895 : }
896 :
897 : static u64 kcpustat_user_vtime(struct vtime *vtime)
898 : {
899 : if (vtime->state == VTIME_USER)
900 : return vtime->utime + vtime_delta(vtime);
901 : else if (vtime->state == VTIME_GUEST)
902 : return vtime->gtime + vtime_delta(vtime);
903 : return 0;
904 : }
905 :
906 : static int kcpustat_field_vtime(u64 *cpustat,
907 : struct task_struct *tsk,
908 : enum cpu_usage_stat usage,
909 : int cpu, u64 *val)
910 : {
911 : struct vtime *vtime = &tsk->vtime;
912 : unsigned int seq;
913 :
914 : do {
915 : int state;
916 :
917 : seq = read_seqcount_begin(&vtime->seqcount);
918 :
919 : state = vtime_state_fetch(vtime, cpu);
920 : if (state < 0)
921 : return state;
922 :
923 : *val = cpustat[usage];
924 :
925 : /*
926 : * Nice VS unnice cputime accounting may be inaccurate if
927 : * the nice value has changed since the last vtime update.
928 : * But proper fix would involve interrupting target on nice
929 : * updates which is a no go on nohz_full (although the scheduler
930 : * may still interrupt the target if rescheduling is needed...)
931 : */
932 : switch (usage) {
933 : case CPUTIME_SYSTEM:
934 : if (state == VTIME_SYS)
935 : *val += vtime->stime + vtime_delta(vtime);
936 : break;
937 : case CPUTIME_USER:
938 : if (task_nice(tsk) <= 0)
939 : *val += kcpustat_user_vtime(vtime);
940 : break;
941 : case CPUTIME_NICE:
942 : if (task_nice(tsk) > 0)
943 : *val += kcpustat_user_vtime(vtime);
944 : break;
945 : case CPUTIME_GUEST:
946 : if (state == VTIME_GUEST && task_nice(tsk) <= 0)
947 : *val += vtime->gtime + vtime_delta(vtime);
948 : break;
949 : case CPUTIME_GUEST_NICE:
950 : if (state == VTIME_GUEST && task_nice(tsk) > 0)
951 : *val += vtime->gtime + vtime_delta(vtime);
952 : break;
953 : default:
954 : break;
955 : }
956 : } while (read_seqcount_retry(&vtime->seqcount, seq));
957 :
958 : return 0;
959 : }
960 :
961 : u64 kcpustat_field(struct kernel_cpustat *kcpustat,
962 : enum cpu_usage_stat usage, int cpu)
963 : {
964 : u64 *cpustat = kcpustat->cpustat;
965 : u64 val = cpustat[usage];
966 : struct rq *rq;
967 : int err;
968 :
969 : if (!vtime_accounting_enabled_cpu(cpu))
970 : return val;
971 :
972 : rq = cpu_rq(cpu);
973 :
974 : for (;;) {
975 : struct task_struct *curr;
976 :
977 : rcu_read_lock();
978 : curr = rcu_dereference(rq->curr);
979 : if (WARN_ON_ONCE(!curr)) {
980 : rcu_read_unlock();
981 : return cpustat[usage];
982 : }
983 :
984 : err = kcpustat_field_vtime(cpustat, curr, usage, cpu, &val);
985 : rcu_read_unlock();
986 :
987 : if (!err)
988 : return val;
989 :
990 : cpu_relax();
991 : }
992 : }
993 : EXPORT_SYMBOL_GPL(kcpustat_field);
994 :
995 : static int kcpustat_cpu_fetch_vtime(struct kernel_cpustat *dst,
996 : const struct kernel_cpustat *src,
997 : struct task_struct *tsk, int cpu)
998 : {
999 : struct vtime *vtime = &tsk->vtime;
1000 : unsigned int seq;
1001 :
1002 : do {
1003 : u64 *cpustat;
1004 : u64 delta;
1005 : int state;
1006 :
1007 : seq = read_seqcount_begin(&vtime->seqcount);
1008 :
1009 : state = vtime_state_fetch(vtime, cpu);
1010 : if (state < 0)
1011 : return state;
1012 :
1013 : *dst = *src;
1014 : cpustat = dst->cpustat;
1015 :
1016 : /* Task is sleeping, dead or idle, nothing to add */
1017 : if (state < VTIME_SYS)
1018 : continue;
1019 :
1020 : delta = vtime_delta(vtime);
1021 :
1022 : /*
1023 : * Task runs either in user (including guest) or kernel space,
1024 : * add pending nohz time to the right place.
1025 : */
1026 : if (state == VTIME_SYS) {
1027 : cpustat[CPUTIME_SYSTEM] += vtime->stime + delta;
1028 : } else if (state == VTIME_USER) {
1029 : if (task_nice(tsk) > 0)
1030 : cpustat[CPUTIME_NICE] += vtime->utime + delta;
1031 : else
1032 : cpustat[CPUTIME_USER] += vtime->utime + delta;
1033 : } else {
1034 : WARN_ON_ONCE(state != VTIME_GUEST);
1035 : if (task_nice(tsk) > 0) {
1036 : cpustat[CPUTIME_GUEST_NICE] += vtime->gtime + delta;
1037 : cpustat[CPUTIME_NICE] += vtime->gtime + delta;
1038 : } else {
1039 : cpustat[CPUTIME_GUEST] += vtime->gtime + delta;
1040 : cpustat[CPUTIME_USER] += vtime->gtime + delta;
1041 : }
1042 : }
1043 : } while (read_seqcount_retry(&vtime->seqcount, seq));
1044 :
1045 : return 0;
1046 : }
1047 :
1048 : void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu)
1049 : {
1050 : const struct kernel_cpustat *src = &kcpustat_cpu(cpu);
1051 : struct rq *rq;
1052 : int err;
1053 :
1054 : if (!vtime_accounting_enabled_cpu(cpu)) {
1055 : *dst = *src;
1056 : return;
1057 : }
1058 :
1059 : rq = cpu_rq(cpu);
1060 :
1061 : for (;;) {
1062 : struct task_struct *curr;
1063 :
1064 : rcu_read_lock();
1065 : curr = rcu_dereference(rq->curr);
1066 : if (WARN_ON_ONCE(!curr)) {
1067 : rcu_read_unlock();
1068 : *dst = *src;
1069 : return;
1070 : }
1071 :
1072 : err = kcpustat_cpu_fetch_vtime(dst, src, curr, cpu);
1073 : rcu_read_unlock();
1074 :
1075 : if (!err)
1076 : return;
1077 :
1078 : cpu_relax();
1079 : }
1080 : }
1081 : EXPORT_SYMBOL_GPL(kcpustat_cpu_fetch);
1082 :
1083 : #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
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