1 #include <linux/export.h>
2 #include <linux/sched.h>
3 #include <linux/tsacct_kern.h>
4 #include <linux/kernel_stat.h>
5 #include <linux/static_key.h>
9 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
12 * There are no locks covering percpu hardirq/softirq time.
13 * They are only modified in vtime_account, on corresponding CPU
14 * with interrupts disabled. So, writes are safe.
15 * They are read and saved off onto struct rq in update_rq_clock().
16 * This may result in other CPU reading this CPU's irq time and can
17 * race with irq/vtime_account on this CPU. We would either get old
18 * or new value with a side effect of accounting a slice of irq time to wrong
19 * task when irq is in progress while we read rq->clock. That is a worthy
20 * compromise in place of having locks on each irq in account_system_time.
22 DEFINE_PER_CPU(u64, cpu_hardirq_time);
23 DEFINE_PER_CPU(u64, cpu_softirq_time);
25 static DEFINE_PER_CPU(u64, irq_start_time);
26 static int sched_clock_irqtime;
28 void enable_sched_clock_irqtime(void)
30 sched_clock_irqtime = 1;
33 void disable_sched_clock_irqtime(void)
35 sched_clock_irqtime = 0;
39 DEFINE_PER_CPU(seqcount_t, irq_time_seq);
40 #endif /* CONFIG_64BIT */
43 * Called before incrementing preempt_count on {soft,}irq_enter
44 * and before decrementing preempt_count on {soft,}irq_exit.
46 void irqtime_account_irq(struct task_struct *curr)
52 if (!sched_clock_irqtime)
55 local_irq_save(flags);
57 cpu = smp_processor_id();
58 delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
59 __this_cpu_add(irq_start_time, delta);
61 irq_time_write_begin();
63 * We do not account for softirq time from ksoftirqd here.
64 * We want to continue accounting softirq time to ksoftirqd thread
65 * in that case, so as not to confuse scheduler with a special task
66 * that do not consume any time, but still wants to run.
69 __this_cpu_add(cpu_hardirq_time, delta);
70 else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
71 __this_cpu_add(cpu_softirq_time, delta);
74 local_irq_restore(flags);
76 EXPORT_SYMBOL_GPL(irqtime_account_irq);
78 static int irqtime_account_hi_update(void)
80 u64 *cpustat = kcpustat_this_cpu->cpustat;
85 local_irq_save(flags);
86 latest_ns = this_cpu_read(cpu_hardirq_time);
87 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
89 local_irq_restore(flags);
93 static int irqtime_account_si_update(void)
95 u64 *cpustat = kcpustat_this_cpu->cpustat;
100 local_irq_save(flags);
101 latest_ns = this_cpu_read(cpu_softirq_time);
102 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
104 local_irq_restore(flags);
108 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
110 #define sched_clock_irqtime (0)
112 #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
114 static inline void task_group_account_field(struct task_struct *p, int index,
117 #ifdef CONFIG_CGROUP_CPUACCT
118 struct kernel_cpustat *kcpustat;
122 * Since all updates are sure to touch the root cgroup, we
123 * get ourselves ahead and touch it first. If the root cgroup
124 * is the only cgroup, then nothing else should be necessary.
127 __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
129 #ifdef CONFIG_CGROUP_CPUACCT
130 if (unlikely(!cpuacct_subsys.active))
135 while (ca && (ca != &root_cpuacct)) {
136 kcpustat = this_cpu_ptr(ca->cpustat);
137 kcpustat->cpustat[index] += tmp;
145 * Account user cpu time to a process.
146 * @p: the process that the cpu time gets accounted to
147 * @cputime: the cpu time spent in user space since the last update
148 * @cputime_scaled: cputime scaled by cpu frequency
150 void account_user_time(struct task_struct *p, cputime_t cputime,
151 cputime_t cputime_scaled)
155 /* Add user time to process. */
157 p->utimescaled += cputime_scaled;
158 account_group_user_time(p, cputime);
160 index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
162 /* Add user time to cpustat. */
163 task_group_account_field(p, index, (__force u64) cputime);
165 /* Account for user time used */
166 acct_update_integrals(p);
170 * Account guest cpu time to a process.
171 * @p: the process that the cpu time gets accounted to
172 * @cputime: the cpu time spent in virtual machine since the last update
173 * @cputime_scaled: cputime scaled by cpu frequency
175 static void account_guest_time(struct task_struct *p, cputime_t cputime,
176 cputime_t cputime_scaled)
178 u64 *cpustat = kcpustat_this_cpu->cpustat;
180 /* Add guest time to process. */
182 p->utimescaled += cputime_scaled;
183 account_group_user_time(p, cputime);
186 /* Add guest time to cpustat. */
187 if (TASK_NICE(p) > 0) {
188 cpustat[CPUTIME_NICE] += (__force u64) cputime;
189 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
191 cpustat[CPUTIME_USER] += (__force u64) cputime;
192 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
197 * Account system cpu time to a process and desired cpustat field
198 * @p: the process that the cpu time gets accounted to
199 * @cputime: the cpu time spent in kernel space since the last update
200 * @cputime_scaled: cputime scaled by cpu frequency
201 * @target_cputime64: pointer to cpustat field that has to be updated
204 void __account_system_time(struct task_struct *p, cputime_t cputime,
205 cputime_t cputime_scaled, int index)
207 /* Add system time to process. */
209 p->stimescaled += cputime_scaled;
210 account_group_system_time(p, cputime);
212 /* Add system time to cpustat. */
213 task_group_account_field(p, index, (__force u64) cputime);
215 /* Account for system time used */
216 acct_update_integrals(p);
220 * Account system cpu time to a process.
221 * @p: the process that the cpu time gets accounted to
222 * @hardirq_offset: the offset to subtract from hardirq_count()
223 * @cputime: the cpu time spent in kernel space since the last update
224 * @cputime_scaled: cputime scaled by cpu frequency
226 void account_system_time(struct task_struct *p, int hardirq_offset,
227 cputime_t cputime, cputime_t cputime_scaled)
231 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
232 account_guest_time(p, cputime, cputime_scaled);
236 if (hardirq_count() - hardirq_offset)
238 else if (in_serving_softirq())
239 index = CPUTIME_SOFTIRQ;
241 index = CPUTIME_SYSTEM;
243 __account_system_time(p, cputime, cputime_scaled, index);
247 * Account for involuntary wait time.
248 * @cputime: the cpu time spent in involuntary wait
250 void account_steal_time(cputime_t cputime)
252 u64 *cpustat = kcpustat_this_cpu->cpustat;
254 cpustat[CPUTIME_STEAL] += (__force u64) cputime;
258 * Account for idle time.
259 * @cputime: the cpu time spent in idle wait
261 void account_idle_time(cputime_t cputime)
263 u64 *cpustat = kcpustat_this_cpu->cpustat;
264 struct rq *rq = this_rq();
266 if (atomic_read(&rq->nr_iowait) > 0)
267 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
269 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
272 static __always_inline bool steal_account_process_tick(void)
274 #ifdef CONFIG_PARAVIRT
275 if (static_key_false(¶virt_steal_enabled)) {
278 steal = paravirt_steal_clock(smp_processor_id());
279 steal -= this_rq()->prev_steal_time;
281 st = steal_ticks(steal);
282 this_rq()->prev_steal_time += st * TICK_NSEC;
284 account_steal_time(st);
292 * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
293 * tasks (sum on group iteration) belonging to @tsk's group.
295 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
297 struct signal_struct *sig = tsk->signal;
298 struct task_struct *t;
300 times->utime = sig->utime;
301 times->stime = sig->stime;
302 times->sum_exec_runtime = sig->sum_sched_runtime;
305 /* make sure we can trust tsk->thread_group list */
306 if (!likely(pid_alive(tsk)))
311 times->utime += t->utime;
312 times->stime += t->stime;
313 times->sum_exec_runtime += task_sched_runtime(t);
314 } while_each_thread(tsk, t);
319 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
321 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
323 * Account a tick to a process and cpustat
324 * @p: the process that the cpu time gets accounted to
325 * @user_tick: is the tick from userspace
326 * @rq: the pointer to rq
328 * Tick demultiplexing follows the order
329 * - pending hardirq update
330 * - pending softirq update
334 * - check for guest_time
335 * - else account as system_time
337 * Check for hardirq is done both for system and user time as there is
338 * no timer going off while we are on hardirq and hence we may never get an
339 * opportunity to update it solely in system time.
340 * p->stime and friends are only updated on system time and not on irq
341 * softirq as those do not count in task exec_runtime any more.
343 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
346 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
347 u64 *cpustat = kcpustat_this_cpu->cpustat;
349 if (steal_account_process_tick())
352 if (irqtime_account_hi_update()) {
353 cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
354 } else if (irqtime_account_si_update()) {
355 cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
356 } else if (this_cpu_ksoftirqd() == p) {
358 * ksoftirqd time do not get accounted in cpu_softirq_time.
359 * So, we have to handle it separately here.
360 * Also, p->stime needs to be updated for ksoftirqd.
362 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
364 } else if (user_tick) {
365 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
366 } else if (p == rq->idle) {
367 account_idle_time(cputime_one_jiffy);
368 } else if (p->flags & PF_VCPU) { /* System time or guest time */
369 account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
371 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
376 static void irqtime_account_idle_ticks(int ticks)
379 struct rq *rq = this_rq();
381 for (i = 0; i < ticks; i++)
382 irqtime_account_process_tick(current, 0, rq);
384 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
385 static void irqtime_account_idle_ticks(int ticks) {}
386 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
388 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
391 * Account a single tick of cpu time.
392 * @p: the process that the cpu time gets accounted to
393 * @user_tick: indicates if the tick is a user or a system tick
395 void account_process_tick(struct task_struct *p, int user_tick)
397 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
398 struct rq *rq = this_rq();
400 if (sched_clock_irqtime) {
401 irqtime_account_process_tick(p, user_tick, rq);
405 if (steal_account_process_tick())
409 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
410 else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
411 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
414 account_idle_time(cputime_one_jiffy);
418 * Account multiple ticks of steal time.
419 * @p: the process from which the cpu time has been stolen
420 * @ticks: number of stolen ticks
422 void account_steal_ticks(unsigned long ticks)
424 account_steal_time(jiffies_to_cputime(ticks));
428 * Account multiple ticks of idle time.
429 * @ticks: number of stolen ticks
431 void account_idle_ticks(unsigned long ticks)
434 if (sched_clock_irqtime) {
435 irqtime_account_idle_ticks(ticks);
439 account_idle_time(jiffies_to_cputime(ticks));
445 * Use precise platform statistics if available:
447 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
448 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
454 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
456 struct task_cputime cputime;
458 thread_group_cputime(p, &cputime);
464 void vtime_account_system_irqsafe(struct task_struct *tsk)
468 local_irq_save(flags);
469 vtime_account_system(tsk);
470 local_irq_restore(flags);
472 EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
474 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
475 void vtime_task_switch(struct task_struct *prev)
477 if (is_idle_task(prev))
478 vtime_account_idle(prev);
480 vtime_account_system(prev);
482 vtime_account_user(prev);
483 arch_vtime_task_switch(prev);
488 * Archs that account the whole time spent in the idle task
489 * (outside irq) as idle time can rely on this and just implement
490 * vtime_account_system() and vtime_account_idle(). Archs that
491 * have other meaning of the idle time (s390 only includes the
492 * time spent by the CPU when it's in low power mode) must override
495 #ifndef __ARCH_HAS_VTIME_ACCOUNT
496 void vtime_account(struct task_struct *tsk)
498 if (in_interrupt() || !is_idle_task(tsk))
499 vtime_account_system(tsk);
501 vtime_account_idle(tsk);
503 EXPORT_SYMBOL_GPL(vtime_account);
504 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
508 #ifndef nsecs_to_cputime
509 # define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
512 static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
514 u64 temp = (__force u64) rtime;
516 temp *= (__force u64) utime;
518 if (sizeof(cputime_t) == 4)
519 temp = div_u64(temp, (__force u32) total);
521 temp = div64_u64(temp, (__force u64) total);
523 return (__force cputime_t) temp;
527 * Adjust tick based cputime random precision against scheduler
528 * runtime accounting.
530 static void cputime_adjust(struct task_cputime *curr,
531 struct cputime *prev,
532 cputime_t *ut, cputime_t *st)
534 cputime_t rtime, utime, total;
537 total = utime + curr->stime;
540 * Tick based cputime accounting depend on random scheduling
541 * timeslices of a task to be interrupted or not by the timer.
542 * Depending on these circumstances, the number of these interrupts
543 * may be over or under-optimistic, matching the real user and system
544 * cputime with a variable precision.
546 * Fix this by scaling these tick based values against the total
547 * runtime accounted by the CFS scheduler.
549 rtime = nsecs_to_cputime(curr->sum_exec_runtime);
552 utime = scale_utime(utime, rtime, total);
557 * If the tick based count grows faster than the scheduler one,
558 * the result of the scaling may go backward.
559 * Let's enforce monotonicity.
561 prev->utime = max(prev->utime, utime);
562 prev->stime = max(prev->stime, rtime - prev->utime);
568 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
570 struct task_cputime cputime = {
573 .sum_exec_runtime = p->se.sum_exec_runtime,
576 cputime_adjust(&cputime, &p->prev_cputime, ut, st);
580 * Must be called with siglock held.
582 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
584 struct task_cputime cputime;
586 thread_group_cputime(p, &cputime);
587 cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);