Define __KERN_ORG__ inserted to differenciate between original scheduler and our...
[projects/modsched/linux.git] / kernel / sched / cputime.c
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>
6 #include <linux/context_tracking.h>
7 #include "sched.h"
8
9
10 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
11
12 /*
13  * There are no locks covering percpu hardirq/softirq time.
14  * They are only modified in vtime_account, on corresponding CPU
15  * with interrupts disabled. So, writes are safe.
16  * They are read and saved off onto struct rq in update_rq_clock().
17  * This may result in other CPU reading this CPU's irq time and can
18  * race with irq/vtime_account on this CPU. We would either get old
19  * or new value with a side effect of accounting a slice of irq time to wrong
20  * task when irq is in progress while we read rq->clock. That is a worthy
21  * compromise in place of having locks on each irq in account_system_time.
22  */
23 DEFINE_PER_CPU(u64, cpu_hardirq_time);
24 DEFINE_PER_CPU(u64, cpu_softirq_time);
25
26 static DEFINE_PER_CPU(u64, irq_start_time);
27 static int sched_clock_irqtime;
28
29 void enable_sched_clock_irqtime(void)
30 {
31         sched_clock_irqtime = 1;
32 }
33
34 void disable_sched_clock_irqtime(void)
35 {
36         sched_clock_irqtime = 0;
37 }
38
39 #ifndef CONFIG_64BIT
40 DEFINE_PER_CPU(seqcount_t, irq_time_seq);
41 #endif /* CONFIG_64BIT */
42
43 /*
44  * Called before incrementing preempt_count on {soft,}irq_enter
45  * and before decrementing preempt_count on {soft,}irq_exit.
46  */
47 void irqtime_account_irq(struct task_struct *curr)
48 {
49         unsigned long flags;
50         s64 delta;
51         int cpu;
52
53         if (!sched_clock_irqtime)
54                 return;
55
56         local_irq_save(flags);
57
58         cpu = smp_processor_id();
59         delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
60         __this_cpu_add(irq_start_time, delta);
61
62         irq_time_write_begin();
63         /*
64          * We do not account for softirq time from ksoftirqd here.
65          * We want to continue accounting softirq time to ksoftirqd thread
66          * in that case, so as not to confuse scheduler with a special task
67          * that do not consume any time, but still wants to run.
68          */
69         if (hardirq_count())
70                 __this_cpu_add(cpu_hardirq_time, delta);
71         else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
72                 __this_cpu_add(cpu_softirq_time, delta);
73
74         irq_time_write_end();
75         local_irq_restore(flags);
76 }
77 EXPORT_SYMBOL_GPL(irqtime_account_irq);
78
79 static int irqtime_account_hi_update(void)
80 {
81         u64 *cpustat = kcpustat_this_cpu->cpustat;
82         unsigned long flags;
83         u64 latest_ns;
84         int ret = 0;
85
86         local_irq_save(flags);
87         latest_ns = this_cpu_read(cpu_hardirq_time);
88         if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
89                 ret = 1;
90         local_irq_restore(flags);
91         return ret;
92 }
93
94 static int irqtime_account_si_update(void)
95 {
96         u64 *cpustat = kcpustat_this_cpu->cpustat;
97         unsigned long flags;
98         u64 latest_ns;
99         int ret = 0;
100
101         local_irq_save(flags);
102         latest_ns = this_cpu_read(cpu_softirq_time);
103         if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
104                 ret = 1;
105         local_irq_restore(flags);
106         return ret;
107 }
108
109 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
110
111 #define sched_clock_irqtime     (0)
112
113 #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
114
115 static inline void task_group_account_field(struct task_struct *p, int index,
116                                             u64 tmp)
117 {
118 #ifdef CONFIG_CGROUP_CPUACCT
119         struct kernel_cpustat *kcpustat;
120         struct cpuacct *ca;
121 #endif
122         /*
123          * Since all updates are sure to touch the root cgroup, we
124          * get ourselves ahead and touch it first. If the root cgroup
125          * is the only cgroup, then nothing else should be necessary.
126          *
127          */
128         __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
129
130 #ifdef CONFIG_CGROUP_CPUACCT
131         if (unlikely(!cpuacct_subsys.active))
132                 return;
133
134         rcu_read_lock();
135         ca = task_ca(p);
136         while (ca && (ca != &root_cpuacct)) {
137                 kcpustat = this_cpu_ptr(ca->cpustat);
138                 kcpustat->cpustat[index] += tmp;
139                 ca = parent_ca(ca);
140         }
141         rcu_read_unlock();
142 #endif
143 }
144
145 /*
146  * Account user cpu time to a process.
147  * @p: the process that the cpu time gets accounted to
148  * @cputime: the cpu time spent in user space since the last update
149  * @cputime_scaled: cputime scaled by cpu frequency
150  */
151 void account_user_time(struct task_struct *p, cputime_t cputime,
152                        cputime_t cputime_scaled)
153 {
154         int index;
155
156         /* Add user time to process. */
157         p->utime += cputime;
158         p->utimescaled += cputime_scaled;
159         account_group_user_time(p, cputime);
160
161         index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
162
163         /* Add user time to cpustat. */
164         task_group_account_field(p, index, (__force u64) cputime);
165
166         /* Account for user time used */
167         acct_account_cputime(p);
168 }
169
170 /*
171  * Account guest cpu time to a process.
172  * @p: the process that the cpu time gets accounted to
173  * @cputime: the cpu time spent in virtual machine since the last update
174  * @cputime_scaled: cputime scaled by cpu frequency
175  */
176 static void account_guest_time(struct task_struct *p, cputime_t cputime,
177                                cputime_t cputime_scaled)
178 {
179         u64 *cpustat = kcpustat_this_cpu->cpustat;
180
181         /* Add guest time to process. */
182         p->utime += cputime;
183         p->utimescaled += cputime_scaled;
184         account_group_user_time(p, cputime);
185         p->gtime += cputime;
186
187         /* Add guest time to cpustat. */
188         if (TASK_NICE(p) > 0) {
189                 cpustat[CPUTIME_NICE] += (__force u64) cputime;
190                 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
191         } else {
192                 cpustat[CPUTIME_USER] += (__force u64) cputime;
193                 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
194         }
195 }
196
197 /*
198  * Account system cpu time to a process and desired cpustat field
199  * @p: the process that the cpu time gets accounted to
200  * @cputime: the cpu time spent in kernel space since the last update
201  * @cputime_scaled: cputime scaled by cpu frequency
202  * @target_cputime64: pointer to cpustat field that has to be updated
203  */
204 static inline
205 void __account_system_time(struct task_struct *p, cputime_t cputime,
206                         cputime_t cputime_scaled, int index)
207 {
208         /* Add system time to process. */
209         p->stime += cputime;
210         p->stimescaled += cputime_scaled;
211         account_group_system_time(p, cputime);
212
213         /* Add system time to cpustat. */
214         task_group_account_field(p, index, (__force u64) cputime);
215
216         /* Account for system time used */
217         acct_account_cputime(p);
218 }
219
220 /*
221  * Account system cpu time to a process.
222  * @p: the process that the cpu time gets accounted to
223  * @hardirq_offset: the offset to subtract from hardirq_count()
224  * @cputime: the cpu time spent in kernel space since the last update
225  * @cputime_scaled: cputime scaled by cpu frequency
226  */
227 void account_system_time(struct task_struct *p, int hardirq_offset,
228                          cputime_t cputime, cputime_t cputime_scaled)
229 {
230         int index;
231
232         if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
233                 account_guest_time(p, cputime, cputime_scaled);
234                 return;
235         }
236
237         if (hardirq_count() - hardirq_offset)
238                 index = CPUTIME_IRQ;
239         else if (in_serving_softirq())
240                 index = CPUTIME_SOFTIRQ;
241         else
242                 index = CPUTIME_SYSTEM;
243
244         __account_system_time(p, cputime, cputime_scaled, index);
245 }
246
247 /*
248  * Account for involuntary wait time.
249  * @cputime: the cpu time spent in involuntary wait
250  */
251 void account_steal_time(cputime_t cputime)
252 {
253         u64 *cpustat = kcpustat_this_cpu->cpustat;
254
255         cpustat[CPUTIME_STEAL] += (__force u64) cputime;
256 }
257
258 /*
259  * Account for idle time.
260  * @cputime: the cpu time spent in idle wait
261  */
262 void account_idle_time(cputime_t cputime)
263 {
264         u64 *cpustat = kcpustat_this_cpu->cpustat;
265         struct rq *rq = this_rq();
266
267         if (atomic_read(&rq->nr_iowait) > 0)
268                 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
269         else
270                 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
271 }
272
273 static __always_inline bool steal_account_process_tick(void)
274 {
275 #ifdef CONFIG_PARAVIRT
276         if (static_key_false(&paravirt_steal_enabled)) {
277                 u64 steal, st = 0;
278
279                 steal = paravirt_steal_clock(smp_processor_id());
280                 steal -= this_rq()->prev_steal_time;
281
282                 st = steal_ticks(steal);
283                 this_rq()->prev_steal_time += st * TICK_NSEC;
284
285                 account_steal_time(st);
286                 return st;
287         }
288 #endif
289         return false;
290 }
291
292 /*
293  * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
294  * tasks (sum on group iteration) belonging to @tsk's group.
295  */
296 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
297 {
298         struct signal_struct *sig = tsk->signal;
299         cputime_t utime, stime;
300         struct task_struct *t;
301
302         times->utime = sig->utime;
303         times->stime = sig->stime;
304         times->sum_exec_runtime = sig->sum_sched_runtime;
305
306         rcu_read_lock();
307         /* make sure we can trust tsk->thread_group list */
308         if (!likely(pid_alive(tsk)))
309                 goto out;
310
311         t = tsk;
312         do {
313                 task_cputime(t, &utime, &stime);
314                 times->utime += utime;
315                 times->stime += stime;
316                 times->sum_exec_runtime += task_sched_runtime(t);
317         } while_each_thread(tsk, t);
318 out:
319         rcu_read_unlock();
320 }
321
322 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
323 /*
324  * Account a tick to a process and cpustat
325  * @p: the process that the cpu time gets accounted to
326  * @user_tick: is the tick from userspace
327  * @rq: the pointer to rq
328  *
329  * Tick demultiplexing follows the order
330  * - pending hardirq update
331  * - pending softirq update
332  * - user_time
333  * - idle_time
334  * - system time
335  *   - check for guest_time
336  *   - else account as system_time
337  *
338  * Check for hardirq is done both for system and user time as there is
339  * no timer going off while we are on hardirq and hence we may never get an
340  * opportunity to update it solely in system time.
341  * p->stime and friends are only updated on system time and not on irq
342  * softirq as those do not count in task exec_runtime any more.
343  */
344 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
345                                                 struct rq *rq)
346 {
347         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
348         u64 *cpustat = kcpustat_this_cpu->cpustat;
349
350         if (steal_account_process_tick())
351                 return;
352
353         if (irqtime_account_hi_update()) {
354                 cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
355         } else if (irqtime_account_si_update()) {
356                 cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
357         } else if (this_cpu_ksoftirqd() == p) {
358                 /*
359                  * ksoftirqd time do not get accounted in cpu_softirq_time.
360                  * So, we have to handle it separately here.
361                  * Also, p->stime needs to be updated for ksoftirqd.
362                  */
363                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
364                                         CPUTIME_SOFTIRQ);
365         } else if (user_tick) {
366                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
367         } else if (p == rq->idle) {
368                 account_idle_time(cputime_one_jiffy);
369         } else if (p->flags & PF_VCPU) { /* System time or guest time */
370                 account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
371         } else {
372                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
373                                         CPUTIME_SYSTEM);
374         }
375 }
376
377 static void irqtime_account_idle_ticks(int ticks)
378 {
379         int i;
380         struct rq *rq = this_rq();
381
382         for (i = 0; i < ticks; i++)
383                 irqtime_account_process_tick(current, 0, rq);
384 }
385 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
386 static inline void irqtime_account_idle_ticks(int ticks) {}
387 static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
388                                                 struct rq *rq) {}
389 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
390
391 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
392 /*
393  * Account a single tick of cpu time.
394  * @p: the process that the cpu time gets accounted to
395  * @user_tick: indicates if the tick is a user or a system tick
396  */
397 void account_process_tick(struct task_struct *p, int user_tick)
398 {
399         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
400         struct rq *rq = this_rq();
401
402         if (vtime_accounting_enabled())
403                 return;
404
405         if (sched_clock_irqtime) {
406                 irqtime_account_process_tick(p, user_tick, rq);
407                 return;
408         }
409
410         if (steal_account_process_tick())
411                 return;
412
413         if (user_tick)
414                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
415         else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
416                 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
417                                     one_jiffy_scaled);
418         else
419                 account_idle_time(cputime_one_jiffy);
420 }
421
422 /*
423  * Account multiple ticks of steal time.
424  * @p: the process from which the cpu time has been stolen
425  * @ticks: number of stolen ticks
426  */
427 void account_steal_ticks(unsigned long ticks)
428 {
429         account_steal_time(jiffies_to_cputime(ticks));
430 }
431
432 /*
433  * Account multiple ticks of idle time.
434  * @ticks: number of stolen ticks
435  */
436 void account_idle_ticks(unsigned long ticks)
437 {
438
439         if (sched_clock_irqtime) {
440                 irqtime_account_idle_ticks(ticks);
441                 return;
442         }
443
444         account_idle_time(jiffies_to_cputime(ticks));
445 }
446 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
447
448 /*
449  * Use precise platform statistics if available:
450  */
451 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
452 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
453 {
454         *ut = p->utime;
455         *st = p->stime;
456 }
457
458 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
459 {
460         struct task_cputime cputime;
461
462         thread_group_cputime(p, &cputime);
463
464         *ut = cputime.utime;
465         *st = cputime.stime;
466 }
467
468 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
469 void vtime_task_switch(struct task_struct *prev)
470 {
471         if (!vtime_accounting_enabled())
472                 return;
473
474         if (is_idle_task(prev))
475                 vtime_account_idle(prev);
476         else
477                 vtime_account_system(prev);
478
479 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
480         vtime_account_user(prev);
481 #endif
482         arch_vtime_task_switch(prev);
483 }
484 #endif
485
486 /*
487  * Archs that account the whole time spent in the idle task
488  * (outside irq) as idle time can rely on this and just implement
489  * vtime_account_system() and vtime_account_idle(). Archs that
490  * have other meaning of the idle time (s390 only includes the
491  * time spent by the CPU when it's in low power mode) must override
492  * vtime_account().
493  */
494 #ifndef __ARCH_HAS_VTIME_ACCOUNT
495 void vtime_account_irq_enter(struct task_struct *tsk)
496 {
497         if (!vtime_accounting_enabled())
498                 return;
499
500         if (!in_interrupt()) {
501                 /*
502                  * If we interrupted user, context_tracking_in_user()
503                  * is 1 because the context tracking don't hook
504                  * on irq entry/exit. This way we know if
505                  * we need to flush user time on kernel entry.
506                  */
507                 if (context_tracking_in_user()) {
508                         vtime_account_user(tsk);
509                         return;
510                 }
511
512                 if (is_idle_task(tsk)) {
513                         vtime_account_idle(tsk);
514                         return;
515                 }
516         }
517         vtime_account_system(tsk);
518 }
519 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
520 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
521
522 #else /* !CONFIG_VIRT_CPU_ACCOUNTING */
523
524 static cputime_t scale_stime(cputime_t stime, cputime_t rtime, cputime_t total)
525 {
526         u64 temp = (__force u64) rtime;
527
528         temp *= (__force u64) stime;
529
530         if (sizeof(cputime_t) == 4)
531                 temp = div_u64(temp, (__force u32) total);
532         else
533                 temp = div64_u64(temp, (__force u64) total);
534
535         return (__force cputime_t) temp;
536 }
537
538 /*
539  * Adjust tick based cputime random precision against scheduler
540  * runtime accounting.
541  */
542 static void cputime_adjust(struct task_cputime *curr,
543                            struct cputime *prev,
544                            cputime_t *ut, cputime_t *st)
545 {
546         cputime_t rtime, stime, total;
547
548         stime = curr->stime;
549         total = stime + curr->utime;
550
551         /*
552          * Tick based cputime accounting depend on random scheduling
553          * timeslices of a task to be interrupted or not by the timer.
554          * Depending on these circumstances, the number of these interrupts
555          * may be over or under-optimistic, matching the real user and system
556          * cputime with a variable precision.
557          *
558          * Fix this by scaling these tick based values against the total
559          * runtime accounted by the CFS scheduler.
560          */
561         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
562
563         if (total)
564                 stime = scale_stime(stime, rtime, total);
565         else
566                 stime = rtime;
567
568         /*
569          * If the tick based count grows faster than the scheduler one,
570          * the result of the scaling may go backward.
571          * Let's enforce monotonicity.
572          */
573         prev->stime = max(prev->stime, stime);
574         prev->utime = max(prev->utime, rtime - prev->stime);
575
576         *ut = prev->utime;
577         *st = prev->stime;
578 }
579
580 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
581 {
582         struct task_cputime cputime = {
583                 .sum_exec_runtime = p->se.sum_exec_runtime,
584         };
585
586         task_cputime(p, &cputime.utime, &cputime.stime);
587         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
588 }
589
590 /*
591  * Must be called with siglock held.
592  */
593 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
594 {
595         struct task_cputime cputime;
596
597         thread_group_cputime(p, &cputime);
598         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
599 }
600 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
601
602 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
603 static unsigned long long vtime_delta(struct task_struct *tsk)
604 {
605         unsigned long long clock;
606
607         clock = local_clock();
608         if (clock < tsk->vtime_snap)
609                 return 0;
610
611         return clock - tsk->vtime_snap;
612 }
613
614 static cputime_t get_vtime_delta(struct task_struct *tsk)
615 {
616         unsigned long long delta = vtime_delta(tsk);
617
618         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
619         tsk->vtime_snap += delta;
620
621         /* CHECKME: always safe to convert nsecs to cputime? */
622         return nsecs_to_cputime(delta);
623 }
624
625 static void __vtime_account_system(struct task_struct *tsk)
626 {
627         cputime_t delta_cpu = get_vtime_delta(tsk);
628
629         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
630 }
631
632 void vtime_account_system(struct task_struct *tsk)
633 {
634         if (!vtime_accounting_enabled())
635                 return;
636
637         write_seqlock(&tsk->vtime_seqlock);
638         __vtime_account_system(tsk);
639         write_sequnlock(&tsk->vtime_seqlock);
640 }
641
642 void vtime_account_irq_exit(struct task_struct *tsk)
643 {
644         if (!vtime_accounting_enabled())
645                 return;
646
647         write_seqlock(&tsk->vtime_seqlock);
648         if (context_tracking_in_user())
649                 tsk->vtime_snap_whence = VTIME_USER;
650         __vtime_account_system(tsk);
651         write_sequnlock(&tsk->vtime_seqlock);
652 }
653
654 void vtime_account_user(struct task_struct *tsk)
655 {
656         cputime_t delta_cpu;
657
658         if (!vtime_accounting_enabled())
659                 return;
660
661         delta_cpu = get_vtime_delta(tsk);
662
663         write_seqlock(&tsk->vtime_seqlock);
664         tsk->vtime_snap_whence = VTIME_SYS;
665         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
666         write_sequnlock(&tsk->vtime_seqlock);
667 }
668
669 void vtime_user_enter(struct task_struct *tsk)
670 {
671         if (!vtime_accounting_enabled())
672                 return;
673
674         write_seqlock(&tsk->vtime_seqlock);
675         tsk->vtime_snap_whence = VTIME_USER;
676         __vtime_account_system(tsk);
677         write_sequnlock(&tsk->vtime_seqlock);
678 }
679
680 void vtime_guest_enter(struct task_struct *tsk)
681 {
682         write_seqlock(&tsk->vtime_seqlock);
683         __vtime_account_system(tsk);
684         current->flags |= PF_VCPU;
685         write_sequnlock(&tsk->vtime_seqlock);
686 }
687
688 void vtime_guest_exit(struct task_struct *tsk)
689 {
690         write_seqlock(&tsk->vtime_seqlock);
691         __vtime_account_system(tsk);
692         current->flags &= ~PF_VCPU;
693         write_sequnlock(&tsk->vtime_seqlock);
694 }
695
696 void vtime_account_idle(struct task_struct *tsk)
697 {
698         cputime_t delta_cpu = get_vtime_delta(tsk);
699
700         account_idle_time(delta_cpu);
701 }
702
703 bool vtime_accounting_enabled(void)
704 {
705         return context_tracking_active();
706 }
707
708 void arch_vtime_task_switch(struct task_struct *prev)
709 {
710         write_seqlock(&prev->vtime_seqlock);
711         prev->vtime_snap_whence = VTIME_SLEEPING;
712         write_sequnlock(&prev->vtime_seqlock);
713
714         write_seqlock(&current->vtime_seqlock);
715         current->vtime_snap_whence = VTIME_SYS;
716         current->vtime_snap = sched_clock();
717         write_sequnlock(&current->vtime_seqlock);
718 }
719
720 void vtime_init_idle(struct task_struct *t)
721 {
722         unsigned long flags;
723
724         write_seqlock_irqsave(&t->vtime_seqlock, flags);
725         t->vtime_snap_whence = VTIME_SYS;
726         t->vtime_snap = sched_clock();
727         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
728 }
729
730 cputime_t task_gtime(struct task_struct *t)
731 {
732         unsigned int seq;
733         cputime_t gtime;
734
735         do {
736                 seq = read_seqbegin(&t->vtime_seqlock);
737
738                 gtime = t->gtime;
739                 if (t->flags & PF_VCPU)
740                         gtime += vtime_delta(t);
741
742         } while (read_seqretry(&t->vtime_seqlock, seq));
743
744         return gtime;
745 }
746
747 /*
748  * Fetch cputime raw values from fields of task_struct and
749  * add up the pending nohz execution time since the last
750  * cputime snapshot.
751  */
752 static void
753 fetch_task_cputime(struct task_struct *t,
754                    cputime_t *u_dst, cputime_t *s_dst,
755                    cputime_t *u_src, cputime_t *s_src,
756                    cputime_t *udelta, cputime_t *sdelta)
757 {
758         unsigned int seq;
759         unsigned long long delta;
760
761         do {
762                 *udelta = 0;
763                 *sdelta = 0;
764
765                 seq = read_seqbegin(&t->vtime_seqlock);
766
767                 if (u_dst)
768                         *u_dst = *u_src;
769                 if (s_dst)
770                         *s_dst = *s_src;
771
772                 /* Task is sleeping, nothing to add */
773                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
774                     is_idle_task(t))
775                         continue;
776
777                 delta = vtime_delta(t);
778
779                 /*
780                  * Task runs either in user or kernel space, add pending nohz time to
781                  * the right place.
782                  */
783                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
784                         *udelta = delta;
785                 } else {
786                         if (t->vtime_snap_whence == VTIME_SYS)
787                                 *sdelta = delta;
788                 }
789         } while (read_seqretry(&t->vtime_seqlock, seq));
790 }
791
792
793 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
794 {
795         cputime_t udelta, sdelta;
796
797         fetch_task_cputime(t, utime, stime, &t->utime,
798                            &t->stime, &udelta, &sdelta);
799         if (utime)
800                 *utime += udelta;
801         if (stime)
802                 *stime += sdelta;
803 }
804
805 void task_cputime_scaled(struct task_struct *t,
806                          cputime_t *utimescaled, cputime_t *stimescaled)
807 {
808         cputime_t udelta, sdelta;
809
810         fetch_task_cputime(t, utimescaled, stimescaled,
811                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
812         if (utimescaled)
813                 *utimescaled += cputime_to_scaled(udelta);
814         if (stimescaled)
815                 *stimescaled += cputime_to_scaled(sdelta);
816 }
817 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */