kernel/sched/cputime.c

   1 #include <linux/cpufreq.h>
   2 #include <linux/export.h>
   3 #include <linux/sched.h>
   4 #include <linux/tsacct_kern.h>
   5 #include <linux/kernel_stat.h>
   6 #include <linux/static_key.h>
   7 #include <linux/context_tracking.h>
   8 #include "sched.h"
   9
  10
  11 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
  12
  13 /*
  14  * There are no locks covering percpu hardirq/softirq time.
  15  * They are only modified in vtime_account, on corresponding CPU
  16  * with interrupts disabled. So, writes are safe.
  17  * They are read and saved off onto struct rq in update_rq_clock().
  18  * This may result in other CPU reading this CPU's irq time and can
  19  * race with irq/vtime_account on this CPU. We would either get old
  20  * or new value with a side effect of accounting a slice of irq time to wrong
  21  * task when irq is in progress while we read rq->clock. That is a worthy
  22  * compromise in place of having locks on each irq in account_system_time.
  23  */
  24 DEFINE_PER_CPU(u64, cpu_hardirq_time);
  25 DEFINE_PER_CPU(u64, cpu_softirq_time);
  26
  27 static DEFINE_PER_CPU(u64, irq_start_time);
  28 static int sched_clock_irqtime;
  29
  30 void enable_sched_clock_irqtime(void)
  31 {
  32         sched_clock_irqtime = 1;
  33 }
  34
  35 void disable_sched_clock_irqtime(void)
  36 {
  37         sched_clock_irqtime = 0;
  38 }
  39
  40 #ifndef CONFIG_64BIT
  41 DEFINE_PER_CPU(seqcount_t, irq_time_seq);
  42 #endif /* CONFIG_64BIT */
  43
  44 /*
  45  * Called before incrementing preempt_count on {soft,}irq_enter
  46  * and before decrementing preempt_count on {soft,}irq_exit.
  47  */
  48 void irqtime_account_irq(struct task_struct *curr)
  49 {
  50         unsigned long flags;
  51         s64 delta;
  52         int cpu;
  53
  54         if (!sched_clock_irqtime)
  55                 return;
  56
  57         local_irq_save(flags);
  58
  59         cpu = smp_processor_id();
  60         delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
  61         __this_cpu_add(irq_start_time, delta);
  62
  63         irq_time_write_begin();
  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 (hardirq_count())
  71                 __this_cpu_add(cpu_hardirq_time, delta);
  72         else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
  73                 __this_cpu_add(cpu_softirq_time, delta);
  74
  75         irq_time_write_end();
  76         local_irq_restore(flags);
  77 }
  78 EXPORT_SYMBOL_GPL(irqtime_account_irq);
  79
  80 static int irqtime_account_hi_update(void)
  81 {
  82         u64 *cpustat = kcpustat_this_cpu->cpustat;
  83         unsigned long flags;
  84         u64 latest_ns;
  85         int ret = 0;
  86
  87         local_irq_save(flags);
  88         latest_ns = this_cpu_read(cpu_hardirq_time);
  89         if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
  90                 ret = 1;
  91         local_irq_restore(flags);
  92         return ret;
  93 }
  94
  95 static int irqtime_account_si_update(void)
  96 {
  97         u64 *cpustat = kcpustat_this_cpu->cpustat;
  98         unsigned long flags;
  99         u64 latest_ns;
 100         int ret = 0;
 101
 102         local_irq_save(flags);
 103         latest_ns = this_cpu_read(cpu_softirq_time);
 104         if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
 105                 ret = 1;
 106         local_irq_restore(flags);
 107         return ret;
 108 }
 109
 110 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
 111
 112 #define sched_clock_irqtime     (0)
 113
 114 #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
 115
 116 static inline void task_group_account_field(struct task_struct *p, int index,
 117                                             u64 tmp)
 118 {
 119         /*
 120          * Since all updates are sure to touch the root cgroup, we
 121          * get ourselves ahead and touch it first. If the root cgroup
 122          * is the only cgroup, then nothing else should be necessary.
 123          *
 124          */
 125         __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
 126
 127         cpuacct_account_field(p, index, tmp);
 128 }
 129
 130 /*
 131  * Account user cpu time to a process.
 132  * @p: the process that the cpu time gets accounted to
 133  * @cputime: the cpu time spent in user space since the last update
 134  * @cputime_scaled: cputime scaled by cpu frequency
 135  */
 136 void account_user_time(struct task_struct *p, cputime_t cputime,
 137                        cputime_t cputime_scaled)
 138 {
 139         int index;
 140
 141         /* Add user time to process. */
 142         p->utime += cputime;
 143         p->utimescaled += cputime_scaled;
 144         account_group_user_time(p, cputime);
 145
 146         index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
 147
 148         /* Add user time to cpustat. */
 149         task_group_account_field(p, index, (__force u64) cputime);
 150
 151         /* Account for user time used */
 152         acct_account_cputime(p);
 153
 154 #ifdef CONFIG_CPU_FREQ_STAT
 155         /* Account power usage for user time */
 156         acct_update_power(p, cputime);
 157 #endif
 158 }
 159
 160 /*
 161  * Account guest cpu time to a process.
 162  * @p: the process that the cpu time gets accounted to
 163  * @cputime: the cpu time spent in virtual machine since the last update
 164  * @cputime_scaled: cputime scaled by cpu frequency
 165  */
 166 static void account_guest_time(struct task_struct *p, cputime_t cputime,
 167                                cputime_t cputime_scaled)
 168 {
 169         u64 *cpustat = kcpustat_this_cpu->cpustat;
 170
 171         /* Add guest time to process. */
 172         p->utime += cputime;
 173         p->utimescaled += cputime_scaled;
 174         account_group_user_time(p, cputime);
 175         p->gtime += cputime;
 176
 177         /* Add guest time to cpustat. */
 178         if (TASK_NICE(p) > 0) {
 179                 cpustat[CPUTIME_NICE] += (__force u64) cputime;
 180                 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
 181         } else {
 182                 cpustat[CPUTIME_USER] += (__force u64) cputime;
 183                 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
 184         }
 185 }
 186
 187 /*
 188  * Account system cpu time to a process and desired cpustat field
 189  * @p: the process that the cpu time gets accounted to
 190  * @cputime: the cpu time spent in kernel space since the last update
 191  * @cputime_scaled: cputime scaled by cpu frequency
 192  * @target_cputime64: pointer to cpustat field that has to be updated
 193  */
 194 static inline
 195 void __account_system_time(struct task_struct *p, cputime_t cputime,
 196                         cputime_t cputime_scaled, int index)
 197 {
 198         /* Add system time to process. */
 199         p->stime += cputime;
 200         p->stimescaled += cputime_scaled;
 201         account_group_system_time(p, cputime);
 202
 203         /* Add system time to cpustat. */
 204         task_group_account_field(p, index, (__force u64) cputime);
 205
 206         /* Account for system time used */
 207         acct_account_cputime(p);
 208
 209 #ifdef CONFIG_CPU_FREQ_STAT
 210         /* Account power usage for system time */
 211         acct_update_power(p, cputime);
 212 #endif
 213 }
 214
 215 /*
 216  * Account system cpu time to a process.
 217  * @p: the process that the cpu time gets accounted to
 218  * @hardirq_offset: the offset to subtract from hardirq_count()
 219  * @cputime: the cpu time spent in kernel space since the last update
 220  * @cputime_scaled: cputime scaled by cpu frequency
 221  */
 222 void account_system_time(struct task_struct *p, int hardirq_offset,
 223                          cputime_t cputime, cputime_t cputime_scaled)
 224 {
 225         int index;
 226
 227         if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
 228                 account_guest_time(p, cputime, cputime_scaled);
 229                 return;
 230         }
 231
 232         if (hardirq_count() - hardirq_offset)
 233                 index = CPUTIME_IRQ;
 234         else if (in_serving_softirq())
 235                 index = CPUTIME_SOFTIRQ;
 236         else
 237                 index = CPUTIME_SYSTEM;
 238
 239         __account_system_time(p, cputime, cputime_scaled, index);
 240 }
 241
 242 /*
 243  * Account for involuntary wait time.
 244  * @cputime: the cpu time spent in involuntary wait
 245  */
 246 void account_steal_time(cputime_t cputime)
 247 {
 248         u64 *cpustat = kcpustat_this_cpu->cpustat;
 249
 250         cpustat[CPUTIME_STEAL] += (__force u64) cputime;
 251 }
 252
 253 /*
 254  * Account for idle time.
 255  * @cputime: the cpu time spent in idle wait
 256  */
 257 void account_idle_time(cputime_t cputime)
 258 {
 259         u64 *cpustat = kcpustat_this_cpu->cpustat;
 260         struct rq *rq = this_rq();
 261
 262         if (atomic_read(&rq->nr_iowait) > 0)
 263                 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
 264         else
 265                 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
 266 }
 267
 268 static __always_inline bool steal_account_process_tick(void)
 269 {
 270 #ifdef CONFIG_PARAVIRT
 271         if (static_key_false(&paravirt_steal_enabled)) {
 272                 u64 steal, st = 0;
 273
 274                 steal = paravirt_steal_clock(smp_processor_id());
 275                 steal -= this_rq()->prev_steal_time;
 276
 277                 st = steal_ticks(steal);
 278                 this_rq()->prev_steal_time += st * TICK_NSEC;
 279
 280                 account_steal_time(st);
 281                 return st;
 282         }
 283 #endif
 284         return false;
 285 }
 286
 287 /*
 288  * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
 289  * tasks (sum on group iteration) belonging to @tsk's group.
 290  */
 291 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 292 {
 293         struct signal_struct *sig = tsk->signal;
 294         cputime_t utime, stime;
 295         struct task_struct *t;
 296
 297         times->utime = sig->utime;
 298         times->stime = sig->stime;
 299         times->sum_exec_runtime = sig->sum_sched_runtime;
 300
 301         rcu_read_lock();
 302         /* make sure we can trust tsk->thread_group list */
 303         if (!likely(pid_alive(tsk)))
 304                 goto out;
 305
 306         t = tsk;
 307         do {
 308                 task_cputime(t, &utime, &stime);
 309                 times->utime += utime;
 310                 times->stime += stime;
 311                 times->sum_exec_runtime += task_sched_runtime(t);
 312         } while_each_thread(tsk, t);
 313 out:
 314         rcu_read_unlock();
 315 }
 316
 317 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
 318 /*
 319  * Account a tick to a process and cpustat
 320  * @p: the process that the cpu time gets accounted to
 321  * @user_tick: is the tick from userspace
 322  * @rq: the pointer to rq
 323  *
 324  * Tick demultiplexing follows the order
 325  * - pending hardirq update
 326  * - pending softirq update
 327  * - user_time
 328  * - idle_time
 329  * - system time
 330  *   - check for guest_time
 331  *   - else account as system_time
 332  *
 333  * Check for hardirq is done both for system and user time as there is
 334  * no timer going off while we are on hardirq and hence we may never get an
 335  * opportunity to update it solely in system time.
 336  * p->stime and friends are only updated on system time and not on irq
 337  * softirq as those do not count in task exec_runtime any more.
 338  */
 339 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 340                                          struct rq *rq, int ticks)
 341 {
 342         cputime_t scaled = cputime_to_scaled(cputime_one_jiffy);
 343         u64 cputime = (__force u64) cputime_one_jiffy;
 344         u64 *cpustat = kcpustat_this_cpu->cpustat;
 345
 346         if (steal_account_process_tick())
 347                 return;
 348
 349         cputime *= ticks;
 350         scaled *= ticks;
 351
 352         if (irqtime_account_hi_update()) {
 353                 cpustat[CPUTIME_IRQ] += cputime;
 354         } else if (irqtime_account_si_update()) {
 355                 cpustat[CPUTIME_SOFTIRQ] += cputime;
 356         } else if (this_cpu_ksoftirqd() == p) {
 357                 /*
 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.
 361                  */
 362                 __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ);
 363         } else if (user_tick) {
 364                 account_user_time(p, cputime, scaled);
 365         } else if (p == rq->idle) {
 366                 account_idle_time(cputime);
 367         } else if (p->flags & PF_VCPU) { /* System time or guest time */
 368                 account_guest_time(p, cputime, scaled);
 369         } else {
 370                 __account_system_time(p, cputime, scaled,       CPUTIME_SYSTEM);
 371         }
 372 }
 373
 374 static void irqtime_account_idle_ticks(int ticks)
 375 {
 376         struct rq *rq = this_rq();
 377
 378         irqtime_account_process_tick(current, 0, rq, ticks);
 379 }
 380 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
 381 static inline void irqtime_account_idle_ticks(int ticks) {}
 382 static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 383                                                 struct rq *rq, int nr_ticks) {}
 384 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 385
 386 /*
 387  * Use precise platform statistics if available:
 388  */
 389 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 390
 391 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
 392 void vtime_task_switch(struct task_struct *prev)
 393 {
 394         if (!vtime_accounting_enabled())
 395                 return;
 396
 397         if (is_idle_task(prev))
 398                 vtime_account_idle(prev);
 399         else
 400                 vtime_account_system(prev);
 401
 402 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 403         vtime_account_user(prev);
 404 #endif
 405         arch_vtime_task_switch(prev);
 406 }
 407 #endif
 408
 409 /*
 410  * Archs that account the whole time spent in the idle task
 411  * (outside irq) as idle time can rely on this and just implement
 412  * vtime_account_system() and vtime_account_idle(). Archs that
 413  * have other meaning of the idle time (s390 only includes the
 414  * time spent by the CPU when it's in low power mode) must override
 415  * vtime_account().
 416  */
 417 #ifndef __ARCH_HAS_VTIME_ACCOUNT
 418 void vtime_account_irq_enter(struct task_struct *tsk)
 419 {
 420         if (!vtime_accounting_enabled())
 421                 return;
 422
 423         if (!in_interrupt()) {
 424                 /*
 425                  * If we interrupted user, context_tracking_in_user()
 426                  * is 1 because the context tracking don't hook
 427                  * on irq entry/exit. This way we know if
 428                  * we need to flush user time on kernel entry.
 429                  */
 430                 if (context_tracking_in_user()) {
 431                         vtime_account_user(tsk);
 432                         return;
 433                 }
 434
 435                 if (is_idle_task(tsk)) {
 436                         vtime_account_idle(tsk);
 437                         return;
 438                 }
 439         }
 440         vtime_account_system(tsk);
 441 }
 442 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
 443 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
 444 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 445
 446
 447 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 448 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 449 {
 450         *ut = p->utime;
 451         *st = p->stime;
 452 }
 453
 454 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 455 {
 456         struct task_cputime cputime;
 457
 458         thread_group_cputime(p, &cputime);
 459
 460         *ut = cputime.utime;
 461         *st = cputime.stime;
 462 }
 463 #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 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 void account_process_tick(struct task_struct *p, int user_tick)
 470 {
 471         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
 472         struct rq *rq = this_rq();
 473
 474         if (vtime_accounting_enabled())
 475                 return;
 476
 477         if (sched_clock_irqtime) {
 478                 irqtime_account_process_tick(p, user_tick, rq, 1);
 479                 return;
 480         }
 481
 482         if (steal_account_process_tick())
 483                 return;
 484
 485         if (user_tick)
 486                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
 487         else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
 488                 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
 489                                     one_jiffy_scaled);
 490         else
 491                 account_idle_time(cputime_one_jiffy);
 492 }
 493
 494 /*
 495  * Account multiple ticks of steal time.
 496  * @p: the process from which the cpu time has been stolen
 497  * @ticks: number of stolen ticks
 498  */
 499 void account_steal_ticks(unsigned long ticks)
 500 {
 501         account_steal_time(jiffies_to_cputime(ticks));
 502 }
 503
 504 /*
 505  * Account multiple ticks of idle time.
 506  * @ticks: number of stolen ticks
 507  */
 508 void account_idle_ticks(unsigned long ticks)
 509 {
 510
 511         if (sched_clock_irqtime) {
 512                 irqtime_account_idle_ticks(ticks);
 513                 return;
 514         }
 515
 516         account_idle_time(jiffies_to_cputime(ticks));
 517 }
 518
 519 /*
 520  * Perform (stime * rtime) / total, but avoid multiplication overflow by
 521  * loosing precision when the numbers are big.
 522  */
 523 static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
 524 {
 525         u64 scaled;
 526
 527         for (;;) {
 528                 /* Make sure "rtime" is the bigger of stime/rtime */
 529                 if (stime > rtime) {
 530                         u64 tmp = rtime; rtime = stime; stime = tmp;
 531                 }
 532
 533                 /* Make sure 'total' fits in 32 bits */
 534                 if (total >> 32)
 535                         goto drop_precision;
 536
 537                 /* Does rtime (and thus stime) fit in 32 bits? */
 538                 if (!(rtime >> 32))
 539                         break;
 540
 541                 /* Can we just balance rtime/stime rather than dropping bits? */
 542                 if (stime >> 31)
 543                         goto drop_precision;
 544
 545                 /* We can grow stime and shrink rtime and try to make them both fit */
 546                 stime <<= 1;
 547                 rtime >>= 1;
 548                 continue;
 549
 550 drop_precision:
 551                 /* We drop from rtime, it has more bits than stime */
 552                 rtime >>= 1;
 553                 total >>= 1;
 554         }
 555
 556         /*
 557          * Make sure gcc understands that this is a 32x32->64 multiply,
 558          * followed by a 64/32->64 divide.
 559          */
 560         scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
 561         return (__force cputime_t) scaled;
 562 }
 563
 564 /*
 565  * Adjust tick based cputime random precision against scheduler
 566  * runtime accounting.
 567  */
 568 static void cputime_adjust(struct task_cputime *curr,
 569                            struct cputime *prev,
 570                            cputime_t *ut, cputime_t *st)
 571 {
 572         cputime_t rtime, stime, utime;
 573
 574         if (vtime_accounting_enabled()) {
 575                 *ut = curr->utime;
 576                 *st = curr->stime;
 577                 return;
 578         }
 579
 580         /*
 581          * Tick based cputime accounting depend on random scheduling
 582          * timeslices of a task to be interrupted or not by the timer.
 583          * Depending on these circumstances, the number of these interrupts
 584          * may be over or under-optimistic, matching the real user and system
 585          * cputime with a variable precision.
 586          *
 587          * Fix this by scaling these tick based values against the total
 588          * runtime accounted by the CFS scheduler.
 589          */
 590         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 591
 592         /*
 593          * Update userspace visible utime/stime values only if actual execution
 594          * time is bigger than already exported. Note that can happen, that we
 595          * provided bigger values due to scaling inaccuracy on big numbers.
 596          */
 597         if (prev->stime + prev->utime >= rtime)
 598                 goto out;
 599
 600         stime = curr->stime;
 601         utime = curr->utime;
 602
 603         if (utime == 0) {
 604                 stime = rtime;
 605         } else if (stime == 0) {
 606                 utime = rtime;
 607         } else {
 608                 cputime_t total = stime + utime;
 609
 610                 stime = scale_stime((__force u64)stime,
 611                                     (__force u64)rtime, (__force u64)total);
 612                 utime = rtime - stime;
 613         }
 614
 615         /*
 616          * If the tick based count grows faster than the scheduler one,
 617          * the result of the scaling may go backward.
 618          * Let's enforce monotonicity.
 619          */
 620         prev->stime = max(prev->stime, stime);
 621         prev->utime = max(prev->utime, utime);
 622
 623 out:
 624         *ut = prev->utime;
 625         *st = prev->stime;
 626 }
 627
 628 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 629 {
 630         struct task_cputime cputime = {
 631                 .sum_exec_runtime = p->se.sum_exec_runtime,
 632         };
 633
 634         task_cputime(p, &cputime.utime, &cputime.stime);
 635         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 636 }
 637
 638 /*
 639  * Must be called with siglock held.
 640  */
 641 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 642 {
 643         struct task_cputime cputime;
 644
 645         thread_group_cputime(p, &cputime);
 646         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 647 }
 648 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 649
 650 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 651 static unsigned long long vtime_delta(struct task_struct *tsk)
 652 {
 653         unsigned long long clock;
 654
 655         clock = local_clock();
 656         if (clock < tsk->vtime_snap)
 657                 return 0;
 658
 659         return clock - tsk->vtime_snap;
 660 }
 661
 662 static cputime_t get_vtime_delta(struct task_struct *tsk)
 663 {
 664         unsigned long long delta = vtime_delta(tsk);
 665
 666         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
 667         tsk->vtime_snap += delta;
 668
 669         /* CHECKME: always safe to convert nsecs to cputime? */
 670         return nsecs_to_cputime(delta);
 671 }
 672
 673 static void __vtime_account_system(struct task_struct *tsk)
 674 {
 675         cputime_t delta_cpu = get_vtime_delta(tsk);
 676
 677         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 678 }
 679
 680 void vtime_account_system(struct task_struct *tsk)
 681 {
 682         if (!vtime_accounting_enabled())
 683                 return;
 684
 685         write_seqlock(&tsk->vtime_seqlock);
 686         __vtime_account_system(tsk);
 687         write_sequnlock(&tsk->vtime_seqlock);
 688 }
 689
 690 void vtime_account_irq_exit(struct task_struct *tsk)
 691 {
 692         if (!vtime_accounting_enabled())
 693                 return;
 694
 695         write_seqlock(&tsk->vtime_seqlock);
 696         if (context_tracking_in_user())
 697                 tsk->vtime_snap_whence = VTIME_USER;
 698         __vtime_account_system(tsk);
 699         write_sequnlock(&tsk->vtime_seqlock);
 700 }
 701
 702 void vtime_account_user(struct task_struct *tsk)
 703 {
 704         cputime_t delta_cpu;
 705
 706         if (!vtime_accounting_enabled())
 707                 return;
 708
 709         delta_cpu = get_vtime_delta(tsk);
 710
 711         write_seqlock(&tsk->vtime_seqlock);
 712         tsk->vtime_snap_whence = VTIME_SYS;
 713         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 714         write_sequnlock(&tsk->vtime_seqlock);
 715 }
 716
 717 void vtime_user_enter(struct task_struct *tsk)
 718 {
 719         if (!vtime_accounting_enabled())
 720                 return;
 721
 722         write_seqlock(&tsk->vtime_seqlock);
 723         tsk->vtime_snap_whence = VTIME_USER;
 724         __vtime_account_system(tsk);
 725         write_sequnlock(&tsk->vtime_seqlock);
 726 }
 727
 728 void vtime_guest_enter(struct task_struct *tsk)
 729 {
 730         write_seqlock(&tsk->vtime_seqlock);
 731         __vtime_account_system(tsk);
 732         current->flags |= PF_VCPU;
 733         write_sequnlock(&tsk->vtime_seqlock);
 734 }
 735
 736 void vtime_guest_exit(struct task_struct *tsk)
 737 {
 738         write_seqlock(&tsk->vtime_seqlock);
 739         __vtime_account_system(tsk);
 740         current->flags &= ~PF_VCPU;
 741         write_sequnlock(&tsk->vtime_seqlock);
 742 }
 743
 744 void vtime_account_idle(struct task_struct *tsk)
 745 {
 746         cputime_t delta_cpu = get_vtime_delta(tsk);
 747
 748         account_idle_time(delta_cpu);
 749 }
 750
 751 bool vtime_accounting_enabled(void)
 752 {
 753         return context_tracking_active();
 754 }
 755
 756 void arch_vtime_task_switch(struct task_struct *prev)
 757 {
 758         write_seqlock(&prev->vtime_seqlock);
 759         prev->vtime_snap_whence = VTIME_SLEEPING;
 760         write_sequnlock(&prev->vtime_seqlock);
 761
 762         write_seqlock(&current->vtime_seqlock);
 763         current->vtime_snap_whence = VTIME_SYS;
 764         current->vtime_snap = sched_clock_cpu(smp_processor_id());
 765         write_sequnlock(&current->vtime_seqlock);
 766 }
 767
 768 void vtime_init_idle(struct task_struct *t, int cpu)
 769 {
 770         unsigned long flags;
 771
 772         write_seqlock_irqsave(&t->vtime_seqlock, flags);
 773         t->vtime_snap_whence = VTIME_SYS;
 774         t->vtime_snap = sched_clock_cpu(cpu);
 775         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
 776 }
 777
 778 cputime_t task_gtime(struct task_struct *t)
 779 {
 780         unsigned int seq;
 781         cputime_t gtime;
 782
 783         do {
 784                 seq = read_seqbegin(&t->vtime_seqlock);
 785
 786                 gtime = t->gtime;
 787                 if (t->flags & PF_VCPU)
 788                         gtime += vtime_delta(t);
 789
 790         } while (read_seqretry(&t->vtime_seqlock, seq));
 791
 792         return gtime;
 793 }
 794
 795 /*
 796  * Fetch cputime raw values from fields of task_struct and
 797  * add up the pending nohz execution time since the last
 798  * cputime snapshot.
 799  */
 800 static void
 801 fetch_task_cputime(struct task_struct *t,
 802                    cputime_t *u_dst, cputime_t *s_dst,
 803                    cputime_t *u_src, cputime_t *s_src,
 804                    cputime_t *udelta, cputime_t *sdelta)
 805 {
 806         unsigned int seq;
 807         unsigned long long delta;
 808
 809         do {
 810                 *udelta = 0;
 811                 *sdelta = 0;
 812
 813                 seq = read_seqbegin(&t->vtime_seqlock);
 814
 815                 if (u_dst)
 816                         *u_dst = *u_src;
 817                 if (s_dst)
 818                         *s_dst = *s_src;
 819
 820                 /* Task is sleeping, nothing to add */
 821                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
 822                     is_idle_task(t))
 823                         continue;
 824
 825                 delta = vtime_delta(t);
 826
 827                 /*
 828                  * Task runs either in user or kernel space, add pending nohz time to
 829                  * the right place.
 830                  */
 831                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
 832                         *udelta = delta;
 833                 } else {
 834                         if (t->vtime_snap_whence == VTIME_SYS)
 835                                 *sdelta = delta;
 836                 }
 837         } while (read_seqretry(&t->vtime_seqlock, seq));
 838 }
 839
 840
 841 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 842 {
 843         cputime_t udelta, sdelta;
 844
 845         fetch_task_cputime(t, utime, stime, &t->utime,
 846                            &t->stime, &udelta, &sdelta);
 847         if (utime)
 848                 *utime += udelta;
 849         if (stime)
 850                 *stime += sdelta;
 851 }
 852
 853 void task_cputime_scaled(struct task_struct *t,
 854                          cputime_t *utimescaled, cputime_t *stimescaled)
 855 {
 856         cputime_t udelta, sdelta;
 857
 858         fetch_task_cputime(t, utimescaled, stimescaled,
 859                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
 860         if (utimescaled)
 861                 *utimescaled += cputime_to_scaled(udelta);
 862         if (stimescaled)
 863                 *stimescaled += cputime_to_scaled(sdelta);
 864 }
 865 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */