| 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 | #ifdef CONFIG_PARAVIRT |
| 9 | #include <asm/paravirt.h> |
| 10 | #endif |
| 11 | |
| 12 | |
| 13 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING |
| 14 | |
| 15 | /* |
| 16 | * There are no locks covering percpu hardirq/softirq time. |
| 17 | * They are only modified in vtime_account, on corresponding CPU |
| 18 | * with interrupts disabled. So, writes are safe. |
| 19 | * They are read and saved off onto struct rq in update_rq_clock(). |
| 20 | * This may result in other CPU reading this CPU's irq time and can |
| 21 | * race with irq/vtime_account on this CPU. We would either get old |
| 22 | * or new value with a side effect of accounting a slice of irq time to wrong |
| 23 | * task when irq is in progress while we read rq->clock. That is a worthy |
| 24 | * compromise in place of having locks on each irq in account_system_time. |
| 25 | */ |
| 26 | DEFINE_PER_CPU(u64, cpu_hardirq_time); |
| 27 | DEFINE_PER_CPU(u64, cpu_softirq_time); |
| 28 | |
| 29 | static DEFINE_PER_CPU(u64, irq_start_time); |
| 30 | static int sched_clock_irqtime; |
| 31 | |
| 32 | void enable_sched_clock_irqtime(void) |
| 33 | { |
| 34 | sched_clock_irqtime = 1; |
| 35 | } |
| 36 | |
| 37 | void disable_sched_clock_irqtime(void) |
| 38 | { |
| 39 | sched_clock_irqtime = 0; |
| 40 | } |
| 41 | |
| 42 | #ifndef CONFIG_64BIT |
| 43 | DEFINE_PER_CPU(seqcount_t, irq_time_seq); |
| 44 | #endif /* CONFIG_64BIT */ |
| 45 | |
| 46 | /* |
| 47 | * Called before incrementing preempt_count on {soft,}irq_enter |
| 48 | * and before decrementing preempt_count on {soft,}irq_exit. |
| 49 | */ |
| 50 | void irqtime_account_irq(struct task_struct *curr) |
| 51 | { |
| 52 | unsigned long flags; |
| 53 | s64 delta; |
| 54 | int cpu; |
| 55 | |
| 56 | if (!sched_clock_irqtime) |
| 57 | return; |
| 58 | |
| 59 | local_irq_save(flags); |
| 60 | |
| 61 | cpu = smp_processor_id(); |
| 62 | delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); |
| 63 | __this_cpu_add(irq_start_time, delta); |
| 64 | |
| 65 | irq_time_write_begin(); |
| 66 | /* |
| 67 | * We do not account for softirq time from ksoftirqd here. |
| 68 | * We want to continue accounting softirq time to ksoftirqd thread |
| 69 | * in that case, so as not to confuse scheduler with a special task |
| 70 | * that do not consume any time, but still wants to run. |
| 71 | */ |
| 72 | if (hardirq_count()) |
| 73 | __this_cpu_add(cpu_hardirq_time, delta); |
| 74 | else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) |
| 75 | __this_cpu_add(cpu_softirq_time, delta); |
| 76 | |
| 77 | irq_time_write_end(); |
| 78 | local_irq_restore(flags); |
| 79 | } |
| 80 | EXPORT_SYMBOL_GPL(irqtime_account_irq); |
| 81 | |
| 82 | static int irqtime_account_hi_update(void) |
| 83 | { |
| 84 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 85 | unsigned long flags; |
| 86 | u64 latest_ns; |
| 87 | int ret = 0; |
| 88 | |
| 89 | local_irq_save(flags); |
| 90 | latest_ns = this_cpu_read(cpu_hardirq_time); |
| 91 | if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ]) |
| 92 | ret = 1; |
| 93 | local_irq_restore(flags); |
| 94 | return ret; |
| 95 | } |
| 96 | |
| 97 | static int irqtime_account_si_update(void) |
| 98 | { |
| 99 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 100 | unsigned long flags; |
| 101 | u64 latest_ns; |
| 102 | int ret = 0; |
| 103 | |
| 104 | local_irq_save(flags); |
| 105 | latest_ns = this_cpu_read(cpu_softirq_time); |
| 106 | if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ]) |
| 107 | ret = 1; |
| 108 | local_irq_restore(flags); |
| 109 | return ret; |
| 110 | } |
| 111 | |
| 112 | #else /* CONFIG_IRQ_TIME_ACCOUNTING */ |
| 113 | |
| 114 | #define sched_clock_irqtime (0) |
| 115 | |
| 116 | #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */ |
| 117 | |
| 118 | static inline void task_group_account_field(struct task_struct *p, int index, |
| 119 | u64 tmp) |
| 120 | { |
| 121 | /* |
| 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. |
| 125 | * |
| 126 | */ |
| 127 | __this_cpu_add(kernel_cpustat.cpustat[index], tmp); |
| 128 | |
| 129 | cpuacct_account_field(p, index, tmp); |
| 130 | } |
| 131 | |
| 132 | /* |
| 133 | * Account user cpu time to a process. |
| 134 | * @p: the process that the cpu time gets accounted to |
| 135 | * @cputime: the cpu time spent in user space since the last update |
| 136 | * @cputime_scaled: cputime scaled by cpu frequency |
| 137 | */ |
| 138 | void account_user_time(struct task_struct *p, cputime_t cputime, |
| 139 | cputime_t cputime_scaled) |
| 140 | { |
| 141 | int index; |
| 142 | |
| 143 | /* Add user time to process. */ |
| 144 | p->utime += cputime; |
| 145 | p->utimescaled += cputime_scaled; |
| 146 | account_group_user_time(p, cputime); |
| 147 | |
| 148 | index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER; |
| 149 | |
| 150 | /* Add user time to cpustat. */ |
| 151 | task_group_account_field(p, index, (__force u64) cputime); |
| 152 | |
| 153 | /* Account for user time used */ |
| 154 | acct_account_cputime(p); |
| 155 | } |
| 156 | |
| 157 | /* |
| 158 | * Account guest cpu time to a process. |
| 159 | * @p: the process that the cpu time gets accounted to |
| 160 | * @cputime: the cpu time spent in virtual machine since the last update |
| 161 | * @cputime_scaled: cputime scaled by cpu frequency |
| 162 | */ |
| 163 | static void account_guest_time(struct task_struct *p, cputime_t cputime, |
| 164 | cputime_t cputime_scaled) |
| 165 | { |
| 166 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 167 | |
| 168 | /* Add guest time to process. */ |
| 169 | p->utime += cputime; |
| 170 | p->utimescaled += cputime_scaled; |
| 171 | account_group_user_time(p, cputime); |
| 172 | p->gtime += cputime; |
| 173 | |
| 174 | /* Add guest time to cpustat. */ |
| 175 | if (task_nice(p) > 0) { |
| 176 | cpustat[CPUTIME_NICE] += (__force u64) cputime; |
| 177 | cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime; |
| 178 | } else { |
| 179 | cpustat[CPUTIME_USER] += (__force u64) cputime; |
| 180 | cpustat[CPUTIME_GUEST] += (__force u64) cputime; |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * Account system cpu time to a process and desired cpustat field |
| 186 | * @p: the process that the cpu time gets accounted to |
| 187 | * @cputime: the cpu time spent in kernel space since the last update |
| 188 | * @cputime_scaled: cputime scaled by cpu frequency |
| 189 | * @target_cputime64: pointer to cpustat field that has to be updated |
| 190 | */ |
| 191 | static inline |
| 192 | void __account_system_time(struct task_struct *p, cputime_t cputime, |
| 193 | cputime_t cputime_scaled, int index) |
| 194 | { |
| 195 | /* Add system time to process. */ |
| 196 | p->stime += cputime; |
| 197 | p->stimescaled += cputime_scaled; |
| 198 | account_group_system_time(p, cputime); |
| 199 | |
| 200 | /* Add system time to cpustat. */ |
| 201 | task_group_account_field(p, index, (__force u64) cputime); |
| 202 | |
| 203 | /* Account for system time used */ |
| 204 | acct_account_cputime(p); |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * Account system cpu time to a process. |
| 209 | * @p: the process that the cpu time gets accounted to |
| 210 | * @hardirq_offset: the offset to subtract from hardirq_count() |
| 211 | * @cputime: the cpu time spent in kernel space since the last update |
| 212 | * @cputime_scaled: cputime scaled by cpu frequency |
| 213 | */ |
| 214 | void account_system_time(struct task_struct *p, int hardirq_offset, |
| 215 | cputime_t cputime, cputime_t cputime_scaled) |
| 216 | { |
| 217 | int index; |
| 218 | |
| 219 | if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { |
| 220 | account_guest_time(p, cputime, cputime_scaled); |
| 221 | return; |
| 222 | } |
| 223 | |
| 224 | if (hardirq_count() - hardirq_offset) |
| 225 | index = CPUTIME_IRQ; |
| 226 | else if (in_serving_softirq()) |
| 227 | index = CPUTIME_SOFTIRQ; |
| 228 | else |
| 229 | index = CPUTIME_SYSTEM; |
| 230 | |
| 231 | __account_system_time(p, cputime, cputime_scaled, index); |
| 232 | } |
| 233 | |
| 234 | /* |
| 235 | * Account for involuntary wait time. |
| 236 | * @cputime: the cpu time spent in involuntary wait |
| 237 | */ |
| 238 | void account_steal_time(cputime_t cputime) |
| 239 | { |
| 240 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 241 | |
| 242 | cpustat[CPUTIME_STEAL] += (__force u64) cputime; |
| 243 | } |
| 244 | |
| 245 | /* |
| 246 | * Account for idle time. |
| 247 | * @cputime: the cpu time spent in idle wait |
| 248 | */ |
| 249 | void account_idle_time(cputime_t cputime) |
| 250 | { |
| 251 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 252 | struct rq *rq = this_rq(); |
| 253 | |
| 254 | if (atomic_read(&rq->nr_iowait) > 0) |
| 255 | cpustat[CPUTIME_IOWAIT] += (__force u64) cputime; |
| 256 | else |
| 257 | cpustat[CPUTIME_IDLE] += (__force u64) cputime; |
| 258 | } |
| 259 | |
| 260 | static __always_inline bool steal_account_process_tick(void) |
| 261 | { |
| 262 | #ifdef CONFIG_PARAVIRT |
| 263 | if (static_key_false(¶virt_steal_enabled)) { |
| 264 | u64 steal; |
| 265 | unsigned long steal_jiffies; |
| 266 | |
| 267 | steal = paravirt_steal_clock(smp_processor_id()); |
| 268 | steal -= this_rq()->prev_steal_time; |
| 269 | |
| 270 | /* |
| 271 | * steal is in nsecs but our caller is expecting steal |
| 272 | * time in jiffies. Lets cast the result to jiffies |
| 273 | * granularity and account the rest on the next rounds. |
| 274 | */ |
| 275 | steal_jiffies = nsecs_to_jiffies(steal); |
| 276 | this_rq()->prev_steal_time += jiffies_to_nsecs(steal_jiffies); |
| 277 | |
| 278 | account_steal_time(jiffies_to_cputime(steal_jiffies)); |
| 279 | return steal_jiffies; |
| 280 | } |
| 281 | #endif |
| 282 | return false; |
| 283 | } |
| 284 | |
| 285 | /* |
| 286 | * Accumulate raw cputime values of dead tasks (sig->[us]time) and live |
| 287 | * tasks (sum on group iteration) belonging to @tsk's group. |
| 288 | */ |
| 289 | void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) |
| 290 | { |
| 291 | struct signal_struct *sig = tsk->signal; |
| 292 | cputime_t utime, stime; |
| 293 | struct task_struct *t; |
| 294 | unsigned int seq, nextseq; |
| 295 | unsigned long flags; |
| 296 | |
| 297 | rcu_read_lock(); |
| 298 | /* Attempt a lockless read on the first round. */ |
| 299 | nextseq = 0; |
| 300 | do { |
| 301 | seq = nextseq; |
| 302 | flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq); |
| 303 | times->utime = sig->utime; |
| 304 | times->stime = sig->stime; |
| 305 | times->sum_exec_runtime = sig->sum_sched_runtime; |
| 306 | |
| 307 | for_each_thread(tsk, t) { |
| 308 | task_cputime(t, &utime, &stime); |
| 309 | times->utime += utime; |
| 310 | times->stime += stime; |
| 311 | times->sum_exec_runtime += task_sched_runtime(t); |
| 312 | } |
| 313 | /* If lockless access failed, take the lock. */ |
| 314 | nextseq = 1; |
| 315 | } while (need_seqretry(&sig->stats_lock, seq)); |
| 316 | done_seqretry_irqrestore(&sig->stats_lock, seq, flags); |
| 317 | rcu_read_unlock(); |
| 318 | } |
| 319 | |
| 320 | #ifdef CONFIG_IRQ_TIME_ACCOUNTING |
| 321 | /* |
| 322 | * Account a tick to a process and cpustat |
| 323 | * @p: the process that the cpu time gets accounted to |
| 324 | * @user_tick: is the tick from userspace |
| 325 | * @rq: the pointer to rq |
| 326 | * |
| 327 | * Tick demultiplexing follows the order |
| 328 | * - pending hardirq update |
| 329 | * - pending softirq update |
| 330 | * - user_time |
| 331 | * - idle_time |
| 332 | * - system time |
| 333 | * - check for guest_time |
| 334 | * - else account as system_time |
| 335 | * |
| 336 | * Check for hardirq is done both for system and user time as there is |
| 337 | * no timer going off while we are on hardirq and hence we may never get an |
| 338 | * opportunity to update it solely in system time. |
| 339 | * p->stime and friends are only updated on system time and not on irq |
| 340 | * softirq as those do not count in task exec_runtime any more. |
| 341 | */ |
| 342 | static void irqtime_account_process_tick(struct task_struct *p, int user_tick, |
| 343 | struct rq *rq, int ticks) |
| 344 | { |
| 345 | cputime_t scaled = cputime_to_scaled(cputime_one_jiffy); |
| 346 | u64 cputime = (__force u64) cputime_one_jiffy; |
| 347 | u64 *cpustat = kcpustat_this_cpu->cpustat; |
| 348 | |
| 349 | if (steal_account_process_tick()) |
| 350 | return; |
| 351 | |
| 352 | cputime *= ticks; |
| 353 | scaled *= ticks; |
| 354 | |
| 355 | if (irqtime_account_hi_update()) { |
| 356 | cpustat[CPUTIME_IRQ] += cputime; |
| 357 | } else if (irqtime_account_si_update()) { |
| 358 | cpustat[CPUTIME_SOFTIRQ] += cputime; |
| 359 | } else if (this_cpu_ksoftirqd() == p) { |
| 360 | /* |
| 361 | * ksoftirqd time do not get accounted in cpu_softirq_time. |
| 362 | * So, we have to handle it separately here. |
| 363 | * Also, p->stime needs to be updated for ksoftirqd. |
| 364 | */ |
| 365 | __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ); |
| 366 | } else if (user_tick) { |
| 367 | account_user_time(p, cputime, scaled); |
| 368 | } else if (p == rq->idle) { |
| 369 | account_idle_time(cputime); |
| 370 | } else if (p->flags & PF_VCPU) { /* System time or guest time */ |
| 371 | account_guest_time(p, cputime, scaled); |
| 372 | } else { |
| 373 | __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM); |
| 374 | } |
| 375 | } |
| 376 | |
| 377 | static void irqtime_account_idle_ticks(int ticks) |
| 378 | { |
| 379 | struct rq *rq = this_rq(); |
| 380 | |
| 381 | irqtime_account_process_tick(current, 0, rq, ticks); |
| 382 | } |
| 383 | #else /* CONFIG_IRQ_TIME_ACCOUNTING */ |
| 384 | static inline void irqtime_account_idle_ticks(int ticks) {} |
| 385 | static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick, |
| 386 | struct rq *rq, int nr_ticks) {} |
| 387 | #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ |
| 388 | |
| 389 | /* |
| 390 | * Use precise platform statistics if available: |
| 391 | */ |
| 392 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING |
| 393 | |
| 394 | #ifndef __ARCH_HAS_VTIME_TASK_SWITCH |
| 395 | void vtime_common_task_switch(struct task_struct *prev) |
| 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_common_account_irq_enter(struct task_struct *tsk) |
| 419 | { |
| 420 | if (!in_interrupt()) { |
| 421 | /* |
| 422 | * If we interrupted user, context_tracking_in_user() |
| 423 | * is 1 because the context tracking don't hook |
| 424 | * on irq entry/exit. This way we know if |
| 425 | * we need to flush user time on kernel entry. |
| 426 | */ |
| 427 | if (context_tracking_in_user()) { |
| 428 | vtime_account_user(tsk); |
| 429 | return; |
| 430 | } |
| 431 | |
| 432 | if (is_idle_task(tsk)) { |
| 433 | vtime_account_idle(tsk); |
| 434 | return; |
| 435 | } |
| 436 | } |
| 437 | vtime_account_system(tsk); |
| 438 | } |
| 439 | EXPORT_SYMBOL_GPL(vtime_common_account_irq_enter); |
| 440 | #endif /* __ARCH_HAS_VTIME_ACCOUNT */ |
| 441 | #endif /* CONFIG_VIRT_CPU_ACCOUNTING */ |
| 442 | |
| 443 | |
| 444 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
| 445 | void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) |
| 446 | { |
| 447 | *ut = p->utime; |
| 448 | *st = p->stime; |
| 449 | } |
| 450 | EXPORT_SYMBOL_GPL(task_cputime_adjusted); |
| 451 | |
| 452 | void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) |
| 453 | { |
| 454 | struct task_cputime cputime; |
| 455 | |
| 456 | thread_group_cputime(p, &cputime); |
| 457 | |
| 458 | *ut = cputime.utime; |
| 459 | *st = cputime.stime; |
| 460 | } |
| 461 | #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ |
| 462 | /* |
| 463 | * Account a single tick of cpu time. |
| 464 | * @p: the process that the cpu time gets accounted to |
| 465 | * @user_tick: indicates if the tick is a user or a system tick |
| 466 | */ |
| 467 | void account_process_tick(struct task_struct *p, int user_tick) |
| 468 | { |
| 469 | cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); |
| 470 | struct rq *rq = this_rq(); |
| 471 | |
| 472 | if (vtime_accounting_cpu_enabled()) |
| 473 | return; |
| 474 | |
| 475 | if (sched_clock_irqtime) { |
| 476 | irqtime_account_process_tick(p, user_tick, rq, 1); |
| 477 | return; |
| 478 | } |
| 479 | |
| 480 | if (steal_account_process_tick()) |
| 481 | return; |
| 482 | |
| 483 | if (user_tick) |
| 484 | account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); |
| 485 | else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) |
| 486 | account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy, |
| 487 | one_jiffy_scaled); |
| 488 | else |
| 489 | account_idle_time(cputime_one_jiffy); |
| 490 | } |
| 491 | |
| 492 | /* |
| 493 | * Account multiple ticks of steal time. |
| 494 | * @p: the process from which the cpu time has been stolen |
| 495 | * @ticks: number of stolen ticks |
| 496 | */ |
| 497 | void account_steal_ticks(unsigned long ticks) |
| 498 | { |
| 499 | account_steal_time(jiffies_to_cputime(ticks)); |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * Account multiple ticks of idle time. |
| 504 | * @ticks: number of stolen ticks |
| 505 | */ |
| 506 | void account_idle_ticks(unsigned long ticks) |
| 507 | { |
| 508 | |
| 509 | if (sched_clock_irqtime) { |
| 510 | irqtime_account_idle_ticks(ticks); |
| 511 | return; |
| 512 | } |
| 513 | |
| 514 | account_idle_time(jiffies_to_cputime(ticks)); |
| 515 | } |
| 516 | |
| 517 | /* |
| 518 | * Perform (stime * rtime) / total, but avoid multiplication overflow by |
| 519 | * loosing precision when the numbers are big. |
| 520 | */ |
| 521 | static cputime_t scale_stime(u64 stime, u64 rtime, u64 total) |
| 522 | { |
| 523 | u64 scaled; |
| 524 | |
| 525 | for (;;) { |
| 526 | /* Make sure "rtime" is the bigger of stime/rtime */ |
| 527 | if (stime > rtime) |
| 528 | swap(rtime, stime); |
| 529 | |
| 530 | /* Make sure 'total' fits in 32 bits */ |
| 531 | if (total >> 32) |
| 532 | goto drop_precision; |
| 533 | |
| 534 | /* Does rtime (and thus stime) fit in 32 bits? */ |
| 535 | if (!(rtime >> 32)) |
| 536 | break; |
| 537 | |
| 538 | /* Can we just balance rtime/stime rather than dropping bits? */ |
| 539 | if (stime >> 31) |
| 540 | goto drop_precision; |
| 541 | |
| 542 | /* We can grow stime and shrink rtime and try to make them both fit */ |
| 543 | stime <<= 1; |
| 544 | rtime >>= 1; |
| 545 | continue; |
| 546 | |
| 547 | drop_precision: |
| 548 | /* We drop from rtime, it has more bits than stime */ |
| 549 | rtime >>= 1; |
| 550 | total >>= 1; |
| 551 | } |
| 552 | |
| 553 | /* |
| 554 | * Make sure gcc understands that this is a 32x32->64 multiply, |
| 555 | * followed by a 64/32->64 divide. |
| 556 | */ |
| 557 | scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total); |
| 558 | return (__force cputime_t) scaled; |
| 559 | } |
| 560 | |
| 561 | /* |
| 562 | * Adjust tick based cputime random precision against scheduler runtime |
| 563 | * accounting. |
| 564 | * |
| 565 | * Tick based cputime accounting depend on random scheduling timeslices of a |
| 566 | * task to be interrupted or not by the timer. Depending on these |
| 567 | * circumstances, the number of these interrupts may be over or |
| 568 | * under-optimistic, matching the real user and system cputime with a variable |
| 569 | * precision. |
| 570 | * |
| 571 | * Fix this by scaling these tick based values against the total runtime |
| 572 | * accounted by the CFS scheduler. |
| 573 | * |
| 574 | * This code provides the following guarantees: |
| 575 | * |
| 576 | * stime + utime == rtime |
| 577 | * stime_i+1 >= stime_i, utime_i+1 >= utime_i |
| 578 | * |
| 579 | * Assuming that rtime_i+1 >= rtime_i. |
| 580 | */ |
| 581 | static void cputime_adjust(struct task_cputime *curr, |
| 582 | struct prev_cputime *prev, |
| 583 | cputime_t *ut, cputime_t *st) |
| 584 | { |
| 585 | cputime_t rtime, stime, utime; |
| 586 | unsigned long flags; |
| 587 | |
| 588 | /* Serialize concurrent callers such that we can honour our guarantees */ |
| 589 | raw_spin_lock_irqsave(&prev->lock, flags); |
| 590 | rtime = nsecs_to_cputime(curr->sum_exec_runtime); |
| 591 | |
| 592 | /* |
| 593 | * This is possible under two circumstances: |
| 594 | * - rtime isn't monotonic after all (a bug); |
| 595 | * - we got reordered by the lock. |
| 596 | * |
| 597 | * In both cases this acts as a filter such that the rest of the code |
| 598 | * can assume it is monotonic regardless of anything else. |
| 599 | */ |
| 600 | if (prev->stime + prev->utime >= rtime) |
| 601 | goto out; |
| 602 | |
| 603 | stime = curr->stime; |
| 604 | utime = curr->utime; |
| 605 | |
| 606 | if (utime == 0) { |
| 607 | stime = rtime; |
| 608 | goto update; |
| 609 | } |
| 610 | |
| 611 | if (stime == 0) { |
| 612 | utime = rtime; |
| 613 | goto update; |
| 614 | } |
| 615 | |
| 616 | stime = scale_stime((__force u64)stime, (__force u64)rtime, |
| 617 | (__force u64)(stime + utime)); |
| 618 | |
| 619 | /* |
| 620 | * Make sure stime doesn't go backwards; this preserves monotonicity |
| 621 | * for utime because rtime is monotonic. |
| 622 | * |
| 623 | * utime_i+1 = rtime_i+1 - stime_i |
| 624 | * = rtime_i+1 - (rtime_i - utime_i) |
| 625 | * = (rtime_i+1 - rtime_i) + utime_i |
| 626 | * >= utime_i |
| 627 | */ |
| 628 | if (stime < prev->stime) |
| 629 | stime = prev->stime; |
| 630 | utime = rtime - stime; |
| 631 | |
| 632 | /* |
| 633 | * Make sure utime doesn't go backwards; this still preserves |
| 634 | * monotonicity for stime, analogous argument to above. |
| 635 | */ |
| 636 | if (utime < prev->utime) { |
| 637 | utime = prev->utime; |
| 638 | stime = rtime - utime; |
| 639 | } |
| 640 | |
| 641 | update: |
| 642 | prev->stime = stime; |
| 643 | prev->utime = utime; |
| 644 | out: |
| 645 | *ut = prev->utime; |
| 646 | *st = prev->stime; |
| 647 | raw_spin_unlock_irqrestore(&prev->lock, flags); |
| 648 | } |
| 649 | |
| 650 | void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) |
| 651 | { |
| 652 | struct task_cputime cputime = { |
| 653 | .sum_exec_runtime = p->se.sum_exec_runtime, |
| 654 | }; |
| 655 | |
| 656 | task_cputime(p, &cputime.utime, &cputime.stime); |
| 657 | cputime_adjust(&cputime, &p->prev_cputime, ut, st); |
| 658 | } |
| 659 | EXPORT_SYMBOL_GPL(task_cputime_adjusted); |
| 660 | |
| 661 | void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) |
| 662 | { |
| 663 | struct task_cputime cputime; |
| 664 | |
| 665 | thread_group_cputime(p, &cputime); |
| 666 | cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st); |
| 667 | } |
| 668 | #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ |
| 669 | |
| 670 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN |
| 671 | static cputime_t vtime_delta(struct task_struct *tsk) |
| 672 | { |
| 673 | unsigned long now = READ_ONCE(jiffies); |
| 674 | |
| 675 | if (time_before(now, (unsigned long)tsk->vtime_snap)) |
| 676 | return 0; |
| 677 | |
| 678 | return jiffies_to_cputime(now - tsk->vtime_snap); |
| 679 | } |
| 680 | |
| 681 | static cputime_t get_vtime_delta(struct task_struct *tsk) |
| 682 | { |
| 683 | unsigned long now = READ_ONCE(jiffies); |
| 684 | unsigned long delta = now - tsk->vtime_snap; |
| 685 | |
| 686 | WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); |
| 687 | tsk->vtime_snap = now; |
| 688 | |
| 689 | return jiffies_to_cputime(delta); |
| 690 | } |
| 691 | |
| 692 | static void __vtime_account_system(struct task_struct *tsk) |
| 693 | { |
| 694 | cputime_t delta_cpu = get_vtime_delta(tsk); |
| 695 | |
| 696 | account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu)); |
| 697 | } |
| 698 | |
| 699 | void vtime_account_system(struct task_struct *tsk) |
| 700 | { |
| 701 | if (!vtime_delta(tsk)) |
| 702 | return; |
| 703 | |
| 704 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 705 | __vtime_account_system(tsk); |
| 706 | write_seqcount_end(&tsk->vtime_seqcount); |
| 707 | } |
| 708 | |
| 709 | void vtime_gen_account_irq_exit(struct task_struct *tsk) |
| 710 | { |
| 711 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 712 | if (vtime_delta(tsk)) |
| 713 | __vtime_account_system(tsk); |
| 714 | if (context_tracking_in_user()) |
| 715 | tsk->vtime_snap_whence = VTIME_USER; |
| 716 | write_seqcount_end(&tsk->vtime_seqcount); |
| 717 | } |
| 718 | |
| 719 | void vtime_account_user(struct task_struct *tsk) |
| 720 | { |
| 721 | cputime_t delta_cpu; |
| 722 | |
| 723 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 724 | tsk->vtime_snap_whence = VTIME_SYS; |
| 725 | if (vtime_delta(tsk)) { |
| 726 | delta_cpu = get_vtime_delta(tsk); |
| 727 | account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu)); |
| 728 | } |
| 729 | write_seqcount_end(&tsk->vtime_seqcount); |
| 730 | } |
| 731 | |
| 732 | void vtime_user_enter(struct task_struct *tsk) |
| 733 | { |
| 734 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 735 | if (vtime_delta(tsk)) |
| 736 | __vtime_account_system(tsk); |
| 737 | tsk->vtime_snap_whence = VTIME_USER; |
| 738 | write_seqcount_end(&tsk->vtime_seqcount); |
| 739 | } |
| 740 | |
| 741 | void vtime_guest_enter(struct task_struct *tsk) |
| 742 | { |
| 743 | /* |
| 744 | * The flags must be updated under the lock with |
| 745 | * the vtime_snap flush and update. |
| 746 | * That enforces a right ordering and update sequence |
| 747 | * synchronization against the reader (task_gtime()) |
| 748 | * that can thus safely catch up with a tickless delta. |
| 749 | */ |
| 750 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 751 | if (vtime_delta(tsk)) |
| 752 | __vtime_account_system(tsk); |
| 753 | current->flags |= PF_VCPU; |
| 754 | write_seqcount_end(&tsk->vtime_seqcount); |
| 755 | } |
| 756 | EXPORT_SYMBOL_GPL(vtime_guest_enter); |
| 757 | |
| 758 | void vtime_guest_exit(struct task_struct *tsk) |
| 759 | { |
| 760 | write_seqcount_begin(&tsk->vtime_seqcount); |
| 761 | __vtime_account_system(tsk); |
| 762 | current->flags &= ~PF_VCPU; |
| 763 | write_seqcount_end(&tsk->vtime_seqcount); |
| 764 | } |
| 765 | EXPORT_SYMBOL_GPL(vtime_guest_exit); |
| 766 | |
| 767 | void vtime_account_idle(struct task_struct *tsk) |
| 768 | { |
| 769 | cputime_t delta_cpu = get_vtime_delta(tsk); |
| 770 | |
| 771 | account_idle_time(delta_cpu); |
| 772 | } |
| 773 | |
| 774 | void arch_vtime_task_switch(struct task_struct *prev) |
| 775 | { |
| 776 | write_seqcount_begin(&prev->vtime_seqcount); |
| 777 | prev->vtime_snap_whence = VTIME_INACTIVE; |
| 778 | write_seqcount_end(&prev->vtime_seqcount); |
| 779 | |
| 780 | write_seqcount_begin(¤t->vtime_seqcount); |
| 781 | current->vtime_snap_whence = VTIME_SYS; |
| 782 | current->vtime_snap = jiffies; |
| 783 | write_seqcount_end(¤t->vtime_seqcount); |
| 784 | } |
| 785 | |
| 786 | void vtime_init_idle(struct task_struct *t, int cpu) |
| 787 | { |
| 788 | unsigned long flags; |
| 789 | |
| 790 | local_irq_save(flags); |
| 791 | write_seqcount_begin(&t->vtime_seqcount); |
| 792 | t->vtime_snap_whence = VTIME_SYS; |
| 793 | t->vtime_snap = jiffies; |
| 794 | write_seqcount_end(&t->vtime_seqcount); |
| 795 | local_irq_restore(flags); |
| 796 | } |
| 797 | |
| 798 | cputime_t task_gtime(struct task_struct *t) |
| 799 | { |
| 800 | unsigned int seq; |
| 801 | cputime_t gtime; |
| 802 | |
| 803 | if (!vtime_accounting_enabled()) |
| 804 | return t->gtime; |
| 805 | |
| 806 | do { |
| 807 | seq = read_seqcount_begin(&t->vtime_seqcount); |
| 808 | |
| 809 | gtime = t->gtime; |
| 810 | if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU) |
| 811 | gtime += vtime_delta(t); |
| 812 | |
| 813 | } while (read_seqcount_retry(&t->vtime_seqcount, seq)); |
| 814 | |
| 815 | return gtime; |
| 816 | } |
| 817 | |
| 818 | /* |
| 819 | * Fetch cputime raw values from fields of task_struct and |
| 820 | * add up the pending nohz execution time since the last |
| 821 | * cputime snapshot. |
| 822 | */ |
| 823 | static void |
| 824 | fetch_task_cputime(struct task_struct *t, |
| 825 | cputime_t *u_dst, cputime_t *s_dst, |
| 826 | cputime_t *u_src, cputime_t *s_src, |
| 827 | cputime_t *udelta, cputime_t *sdelta) |
| 828 | { |
| 829 | unsigned int seq; |
| 830 | unsigned long long delta; |
| 831 | |
| 832 | do { |
| 833 | *udelta = 0; |
| 834 | *sdelta = 0; |
| 835 | |
| 836 | seq = read_seqcount_begin(&t->vtime_seqcount); |
| 837 | |
| 838 | if (u_dst) |
| 839 | *u_dst = *u_src; |
| 840 | if (s_dst) |
| 841 | *s_dst = *s_src; |
| 842 | |
| 843 | /* Task is sleeping, nothing to add */ |
| 844 | if (t->vtime_snap_whence == VTIME_INACTIVE || |
| 845 | is_idle_task(t)) |
| 846 | continue; |
| 847 | |
| 848 | delta = vtime_delta(t); |
| 849 | |
| 850 | /* |
| 851 | * Task runs either in user or kernel space, add pending nohz time to |
| 852 | * the right place. |
| 853 | */ |
| 854 | if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) { |
| 855 | *udelta = delta; |
| 856 | } else { |
| 857 | if (t->vtime_snap_whence == VTIME_SYS) |
| 858 | *sdelta = delta; |
| 859 | } |
| 860 | } while (read_seqcount_retry(&t->vtime_seqcount, seq)); |
| 861 | } |
| 862 | |
| 863 | |
| 864 | void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) |
| 865 | { |
| 866 | cputime_t udelta, sdelta; |
| 867 | |
| 868 | if (!vtime_accounting_enabled()) { |
| 869 | if (utime) |
| 870 | *utime = t->utime; |
| 871 | if (stime) |
| 872 | *stime = t->stime; |
| 873 | return; |
| 874 | } |
| 875 | |
| 876 | fetch_task_cputime(t, utime, stime, &t->utime, |
| 877 | &t->stime, &udelta, &sdelta); |
| 878 | if (utime) |
| 879 | *utime += udelta; |
| 880 | if (stime) |
| 881 | *stime += sdelta; |
| 882 | } |
| 883 | |
| 884 | void task_cputime_scaled(struct task_struct *t, |
| 885 | cputime_t *utimescaled, cputime_t *stimescaled) |
| 886 | { |
| 887 | cputime_t udelta, sdelta; |
| 888 | |
| 889 | if (!vtime_accounting_enabled()) { |
| 890 | if (utimescaled) |
| 891 | *utimescaled = t->utimescaled; |
| 892 | if (stimescaled) |
| 893 | *stimescaled = t->stimescaled; |
| 894 | return; |
| 895 | } |
| 896 | |
| 897 | fetch_task_cputime(t, utimescaled, stimescaled, |
| 898 | &t->utimescaled, &t->stimescaled, &udelta, &sdelta); |
| 899 | if (utimescaled) |
| 900 | *utimescaled += cputime_to_scaled(udelta); |
| 901 | if (stimescaled) |
| 902 | *stimescaled += cputime_to_scaled(sdelta); |
| 903 | } |
| 904 | #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */ |