#include #include #include #include #include #include #include "sched.h" #ifdef CONFIG_PARAVIRT #include #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING /* * There are no locks covering percpu hardirq/softirq time. * They are only modified in vtime_account, on corresponding CPU * with interrupts disabled. So, writes are safe. * They are read and saved off onto struct rq in update_rq_clock(). * This may result in other CPU reading this CPU's irq time and can * race with irq/vtime_account on this CPU. We would either get old * or new value with a side effect of accounting a slice of irq time to wrong * task when irq is in progress while we read rq->clock. That is a worthy * compromise in place of having locks on each irq in account_system_time. */ DEFINE_PER_CPU(u64, cpu_hardirq_time); DEFINE_PER_CPU(u64, cpu_softirq_time); static DEFINE_PER_CPU(u64, irq_start_time); static int sched_clock_irqtime; void enable_sched_clock_irqtime(void) { sched_clock_irqtime = 1; } void disable_sched_clock_irqtime(void) { sched_clock_irqtime = 0; } #ifndef CONFIG_64BIT DEFINE_PER_CPU(seqcount_t, irq_time_seq); #endif /* CONFIG_64BIT */ /* * Called before incrementing preempt_count on {soft,}irq_enter * and before decrementing preempt_count on {soft,}irq_exit. */ void irqtime_account_irq(struct task_struct *curr) { s64 delta; int cpu; if (!sched_clock_irqtime) return; cpu = smp_processor_id(); delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); __this_cpu_add(irq_start_time, delta); irq_time_write_begin(); /* * We do not account for softirq time from ksoftirqd here. * We want to continue accounting softirq time to ksoftirqd thread * in that case, so as not to confuse scheduler with a special task * that do not consume any time, but still wants to run. */ if (hardirq_count()) __this_cpu_add(cpu_hardirq_time, delta); else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) __this_cpu_add(cpu_softirq_time, delta); irq_time_write_end(); } EXPORT_SYMBOL_GPL(irqtime_account_irq); static cputime_t irqtime_account_hi_update(cputime_t maxtime) { u64 *cpustat = kcpustat_this_cpu->cpustat; unsigned long flags; cputime_t irq_cputime; local_irq_save(flags); irq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_hardirq_time)) - cpustat[CPUTIME_IRQ]; irq_cputime = min(irq_cputime, maxtime); cpustat[CPUTIME_IRQ] += irq_cputime; local_irq_restore(flags); return irq_cputime; } static cputime_t irqtime_account_si_update(cputime_t maxtime) { u64 *cpustat = kcpustat_this_cpu->cpustat; unsigned long flags; cputime_t softirq_cputime; local_irq_save(flags); softirq_cputime = nsecs_to_cputime64(this_cpu_read(cpu_softirq_time)) - cpustat[CPUTIME_SOFTIRQ]; softirq_cputime = min(softirq_cputime, maxtime); cpustat[CPUTIME_SOFTIRQ] += softirq_cputime; local_irq_restore(flags); return softirq_cputime; } #else /* CONFIG_IRQ_TIME_ACCOUNTING */ #define sched_clock_irqtime (0) static cputime_t irqtime_account_hi_update(cputime_t dummy) { return 0; } static cputime_t irqtime_account_si_update(cputime_t dummy) { return 0; } #endif /* !CONFIG_IRQ_TIME_ACCOUNTING */ static inline void task_group_account_field(struct task_struct *p, int index, u64 tmp) { /* * Since all updates are sure to touch the root cgroup, we * get ourselves ahead and touch it first. If the root cgroup * is the only cgroup, then nothing else should be necessary. * */ __this_cpu_add(kernel_cpustat.cpustat[index], tmp); cpuacct_account_field(p, index, tmp); } /* * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in user space since the last update * @cputime_scaled: cputime scaled by cpu frequency */ void account_user_time(struct task_struct *p, cputime_t cputime, cputime_t cputime_scaled) { int index; /* Add user time to process. */ p->utime += cputime; p->utimescaled += cputime_scaled; account_group_user_time(p, cputime); index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER; /* Add user time to cpustat. */ task_group_account_field(p, index, (__force u64) cputime); /* Account for user time used */ acct_account_cputime(p); } /* * Account guest cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in virtual machine since the last update * @cputime_scaled: cputime scaled by cpu frequency */ static void account_guest_time(struct task_struct *p, cputime_t cputime, cputime_t cputime_scaled) { u64 *cpustat = kcpustat_this_cpu->cpustat; /* Add guest time to process. */ p->utime += cputime; p->utimescaled += cputime_scaled; account_group_user_time(p, cputime); p->gtime += cputime; /* Add guest time to cpustat. */ if (task_nice(p) > 0) { cpustat[CPUTIME_NICE] += (__force u64) cputime; cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime; } else { cpustat[CPUTIME_USER] += (__force u64) cputime; cpustat[CPUTIME_GUEST] += (__force u64) cputime; } } /* * Account system cpu time to a process and desired cpustat field * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in kernel space since the last update * @cputime_scaled: cputime scaled by cpu frequency * @target_cputime64: pointer to cpustat field that has to be updated */ static inline void __account_system_time(struct task_struct *p, cputime_t cputime, cputime_t cputime_scaled, int index) { /* Add system time to process. */ p->stime += cputime; p->stimescaled += cputime_scaled; account_group_system_time(p, cputime); /* Add system time to cpustat. */ task_group_account_field(p, index, (__force u64) cputime); /* Account for system time used */ acct_account_cputime(p); } /* * Account system cpu time to a process. * @p: the process that the cpu time gets accounted to * @hardirq_offset: the offset to subtract from hardirq_count() * @cputime: the cpu time spent in kernel space since the last update * @cputime_scaled: cputime scaled by cpu frequency */ void account_system_time(struct task_struct *p, int hardirq_offset, cputime_t cputime, cputime_t cputime_scaled) { int index; if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { account_guest_time(p, cputime, cputime_scaled); return; } if (hardirq_count() - hardirq_offset) index = CPUTIME_IRQ; else if (in_serving_softirq()) index = CPUTIME_SOFTIRQ; else index = CPUTIME_SYSTEM; __account_system_time(p, cputime, cputime_scaled, index); } /* * Account for involuntary wait time. * @cputime: the cpu time spent in involuntary wait */ void account_steal_time(cputime_t cputime) { u64 *cpustat = kcpustat_this_cpu->cpustat; cpustat[CPUTIME_STEAL] += (__force u64) cputime; } /* * Account for idle time. * @cputime: the cpu time spent in idle wait */ void account_idle_time(cputime_t cputime) { u64 *cpustat = kcpustat_this_cpu->cpustat; struct rq *rq = this_rq(); if (atomic_read(&rq->nr_iowait) > 0) cpustat[CPUTIME_IOWAIT] += (__force u64) cputime; else cpustat[CPUTIME_IDLE] += (__force u64) cputime; } static __always_inline cputime_t steal_account_process_time(cputime_t maxtime) { #ifdef CONFIG_PARAVIRT if (static_key_false(¶virt_steal_enabled)) { cputime_t steal_cputime; u64 steal; steal = paravirt_steal_clock(smp_processor_id()); steal -= this_rq()->prev_steal_time; steal_cputime = min(nsecs_to_cputime(steal), maxtime); account_steal_time(steal_cputime); this_rq()->prev_steal_time += cputime_to_nsecs(steal_cputime); return steal_cputime; } #endif return 0; } /* * Account how much elapsed time was spent in steal, irq, or softirq time. */ static inline cputime_t account_other_time(cputime_t max) { cputime_t accounted; accounted = steal_account_process_time(max); if (accounted < max) accounted += irqtime_account_hi_update(max - accounted); if (accounted < max) accounted += irqtime_account_si_update(max - accounted); return accounted; } /* * Accumulate raw cputime values of dead tasks (sig->[us]time) and live * tasks (sum on group iteration) belonging to @tsk's group. */ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) { struct signal_struct *sig = tsk->signal; cputime_t utime, stime; struct task_struct *t; unsigned int seq, nextseq; unsigned long flags; rcu_read_lock(); /* Attempt a lockless read on the first round. */ nextseq = 0; do { seq = nextseq; flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq); times->utime = sig->utime; times->stime = sig->stime; times->sum_exec_runtime = sig->sum_sched_runtime; for_each_thread(tsk, t) { task_cputime(t, &utime, &stime); times->utime += utime; times->stime += stime; times->sum_exec_runtime += task_sched_runtime(t); } /* If lockless access failed, take the lock. */ nextseq = 1; } while (need_seqretry(&sig->stats_lock, seq)); done_seqretry_irqrestore(&sig->stats_lock, seq, flags); rcu_read_unlock(); } #ifdef CONFIG_IRQ_TIME_ACCOUNTING /* * Account a tick to a process and cpustat * @p: the process that the cpu time gets accounted to * @user_tick: is the tick from userspace * @rq: the pointer to rq * * Tick demultiplexing follows the order * - pending hardirq update * - pending softirq update * - user_time * - idle_time * - system time * - check for guest_time * - else account as system_time * * Check for hardirq is done both for system and user time as there is * no timer going off while we are on hardirq and hence we may never get an * opportunity to update it solely in system time. * p->stime and friends are only updated on system time and not on irq * softirq as those do not count in task exec_runtime any more. */ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, struct rq *rq, int ticks) { u64 cputime = (__force u64) cputime_one_jiffy * ticks; cputime_t scaled, other; /* * When returning from idle, many ticks can get accounted at * once, including some ticks of steal, irq, and softirq time. * Subtract those ticks from the amount of time accounted to * idle, or potentially user or system time. Due to rounding, * other time can exceed ticks occasionally. */ other = account_other_time(cputime); if (other >= cputime) return; cputime -= other; scaled = cputime_to_scaled(cputime); if (this_cpu_ksoftirqd() == p) { /* * ksoftirqd time do not get accounted in cpu_softirq_time. * So, we have to handle it separately here. * Also, p->stime needs to be updated for ksoftirqd. */ __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ); } else if (user_tick) { account_user_time(p, cputime, scaled); } else if (p == rq->idle) { account_idle_time(cputime); } else if (p->flags & PF_VCPU) { /* System time or guest time */ account_guest_time(p, cputime, scaled); } else { __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM); } } static void irqtime_account_idle_ticks(int ticks) { struct rq *rq = this_rq(); irqtime_account_process_tick(current, 0, rq, ticks); } #else /* CONFIG_IRQ_TIME_ACCOUNTING */ static inline void irqtime_account_idle_ticks(int ticks) {} static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick, struct rq *rq, int nr_ticks) {} #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ /* * Use precise platform statistics if available: */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING #ifndef __ARCH_HAS_VTIME_TASK_SWITCH void vtime_common_task_switch(struct task_struct *prev) { if (is_idle_task(prev)) vtime_account_idle(prev); else vtime_account_system(prev); #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE vtime_account_user(prev); #endif arch_vtime_task_switch(prev); } #endif #endif /* CONFIG_VIRT_CPU_ACCOUNTING */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE /* * Archs that account the whole time spent in the idle task * (outside irq) as idle time can rely on this and just implement * vtime_account_system() and vtime_account_idle(). Archs that * have other meaning of the idle time (s390 only includes the * time spent by the CPU when it's in low power mode) must override * vtime_account(). */ #ifndef __ARCH_HAS_VTIME_ACCOUNT void vtime_account_irq_enter(struct task_struct *tsk) { if (!in_interrupt() && is_idle_task(tsk)) vtime_account_idle(tsk); else vtime_account_system(tsk); } EXPORT_SYMBOL_GPL(vtime_account_irq_enter); #endif /* __ARCH_HAS_VTIME_ACCOUNT */ void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) { *ut = p->utime; *st = p->stime; } EXPORT_SYMBOL_GPL(task_cputime_adjusted); void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct task_cputime cputime; thread_group_cputime(p, &cputime); *ut = cputime.utime; *st = cputime.stime; } #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ /* * Account a single tick of cpu time. * @p: the process that the cpu time gets accounted to * @user_tick: indicates if the tick is a user or a system tick */ void account_process_tick(struct task_struct *p, int user_tick) { cputime_t cputime, scaled, steal; struct rq *rq = this_rq(); if (vtime_accounting_cpu_enabled()) return; if (sched_clock_irqtime) { irqtime_account_process_tick(p, user_tick, rq, 1); return; } cputime = cputime_one_jiffy; steal = steal_account_process_time(cputime); if (steal >= cputime) return; cputime -= steal; scaled = cputime_to_scaled(cputime); if (user_tick) account_user_time(p, cputime, scaled); else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) account_system_time(p, HARDIRQ_OFFSET, cputime, scaled); else account_idle_time(cputime); } /* * Account multiple ticks of idle time. * @ticks: number of stolen ticks */ void account_idle_ticks(unsigned long ticks) { cputime_t cputime, steal; if (sched_clock_irqtime) { irqtime_account_idle_ticks(ticks); return; } cputime = cputime_one_jiffy; steal = steal_account_process_time(cputime); if (steal >= cputime) return; cputime -= steal; account_idle_time(cputime); } /* * Perform (stime * rtime) / total, but avoid multiplication overflow by * loosing precision when the numbers are big. */ static cputime_t scale_stime(u64 stime, u64 rtime, u64 total) { u64 scaled; for (;;) { /* Make sure "rtime" is the bigger of stime/rtime */ if (stime > rtime) swap(rtime, stime); /* Make sure 'total' fits in 32 bits */ if (total >> 32) goto drop_precision; /* Does rtime (and thus stime) fit in 32 bits? */ if (!(rtime >> 32)) break; /* Can we just balance rtime/stime rather than dropping bits? */ if (stime >> 31) goto drop_precision; /* We can grow stime and shrink rtime and try to make them both fit */ stime <<= 1; rtime >>= 1; continue; drop_precision: /* We drop from rtime, it has more bits than stime */ rtime >>= 1; total >>= 1; } /* * Make sure gcc understands that this is a 32x32->64 multiply, * followed by a 64/32->64 divide. */ scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total); return (__force cputime_t) scaled; } /* * Adjust tick based cputime random precision against scheduler runtime * accounting. * * Tick based cputime accounting depend on random scheduling timeslices of a * task to be interrupted or not by the timer. Depending on these * circumstances, the number of these interrupts may be over or * under-optimistic, matching the real user and system cputime with a variable * precision. * * Fix this by scaling these tick based values against the total runtime * accounted by the CFS scheduler. * * This code provides the following guarantees: * * stime + utime == rtime * stime_i+1 >= stime_i, utime_i+1 >= utime_i * * Assuming that rtime_i+1 >= rtime_i. */ static void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev, cputime_t *ut, cputime_t *st) { cputime_t rtime, stime, utime; unsigned long flags; /* Serialize concurrent callers such that we can honour our guarantees */ raw_spin_lock_irqsave(&prev->lock, flags); rtime = nsecs_to_cputime(curr->sum_exec_runtime); /* * This is possible under two circumstances: * - rtime isn't monotonic after all (a bug); * - we got reordered by the lock. * * In both cases this acts as a filter such that the rest of the code * can assume it is monotonic regardless of anything else. */ if (prev->stime + prev->utime >= rtime) goto out; stime = curr->stime; utime = curr->utime; if (utime == 0) { stime = rtime; goto update; } if (stime == 0) { utime = rtime; goto update; } stime = scale_stime((__force u64)stime, (__force u64)rtime, (__force u64)(stime + utime)); /* * Make sure stime doesn't go backwards; this preserves monotonicity * for utime because rtime is monotonic. * * utime_i+1 = rtime_i+1 - stime_i * = rtime_i+1 - (rtime_i - utime_i) * = (rtime_i+1 - rtime_i) + utime_i * >= utime_i */ if (stime < prev->stime) stime = prev->stime; utime = rtime - stime; /* * Make sure utime doesn't go backwards; this still preserves * monotonicity for stime, analogous argument to above. */ if (utime < prev->utime) { utime = prev->utime; stime = rtime - utime; } update: prev->stime = stime; prev->utime = utime; out: *ut = prev->utime; *st = prev->stime; raw_spin_unlock_irqrestore(&prev->lock, flags); } void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct task_cputime cputime = { .sum_exec_runtime = p->se.sum_exec_runtime, }; task_cputime(p, &cputime.utime, &cputime.stime); cputime_adjust(&cputime, &p->prev_cputime, ut, st); } EXPORT_SYMBOL_GPL(task_cputime_adjusted); void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st) { struct task_cputime cputime; thread_group_cputime(p, &cputime); cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st); } #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN static cputime_t vtime_delta(struct task_struct *tsk) { unsigned long now = READ_ONCE(jiffies); if (time_before(now, (unsigned long)tsk->vtime_snap)) return 0; return jiffies_to_cputime(now - tsk->vtime_snap); } static cputime_t get_vtime_delta(struct task_struct *tsk) { unsigned long now = READ_ONCE(jiffies); cputime_t delta, other; delta = jiffies_to_cputime(now - tsk->vtime_snap); other = account_other_time(delta); WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); tsk->vtime_snap = now; return delta - other; } static void __vtime_account_system(struct task_struct *tsk) { cputime_t delta_cpu = get_vtime_delta(tsk); account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu)); } void vtime_account_system(struct task_struct *tsk) { if (!vtime_delta(tsk)) return; write_seqcount_begin(&tsk->vtime_seqcount); __vtime_account_system(tsk); write_seqcount_end(&tsk->vtime_seqcount); } void vtime_account_user(struct task_struct *tsk) { cputime_t delta_cpu; write_seqcount_begin(&tsk->vtime_seqcount); tsk->vtime_snap_whence = VTIME_SYS; if (vtime_delta(tsk)) { delta_cpu = get_vtime_delta(tsk); account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu)); } write_seqcount_end(&tsk->vtime_seqcount); } void vtime_user_enter(struct task_struct *tsk) { write_seqcount_begin(&tsk->vtime_seqcount); if (vtime_delta(tsk)) __vtime_account_system(tsk); tsk->vtime_snap_whence = VTIME_USER; write_seqcount_end(&tsk->vtime_seqcount); } void vtime_guest_enter(struct task_struct *tsk) { /* * The flags must be updated under the lock with * the vtime_snap flush and update. * That enforces a right ordering and update sequence * synchronization against the reader (task_gtime()) * that can thus safely catch up with a tickless delta. */ write_seqcount_begin(&tsk->vtime_seqcount); if (vtime_delta(tsk)) __vtime_account_system(tsk); current->flags |= PF_VCPU; write_seqcount_end(&tsk->vtime_seqcount); } EXPORT_SYMBOL_GPL(vtime_guest_enter); void vtime_guest_exit(struct task_struct *tsk) { write_seqcount_begin(&tsk->vtime_seqcount); __vtime_account_system(tsk); current->flags &= ~PF_VCPU; write_seqcount_end(&tsk->vtime_seqcount); } EXPORT_SYMBOL_GPL(vtime_guest_exit); void vtime_account_idle(struct task_struct *tsk) { cputime_t delta_cpu = get_vtime_delta(tsk); account_idle_time(delta_cpu); } void arch_vtime_task_switch(struct task_struct *prev) { write_seqcount_begin(&prev->vtime_seqcount); prev->vtime_snap_whence = VTIME_INACTIVE; write_seqcount_end(&prev->vtime_seqcount); write_seqcount_begin(¤t->vtime_seqcount); current->vtime_snap_whence = VTIME_SYS; current->vtime_snap = jiffies; write_seqcount_end(¤t->vtime_seqcount); } void vtime_init_idle(struct task_struct *t, int cpu) { unsigned long flags; local_irq_save(flags); write_seqcount_begin(&t->vtime_seqcount); t->vtime_snap_whence = VTIME_SYS; t->vtime_snap = jiffies; write_seqcount_end(&t->vtime_seqcount); local_irq_restore(flags); } cputime_t task_gtime(struct task_struct *t) { unsigned int seq; cputime_t gtime; if (!vtime_accounting_enabled()) return t->gtime; do { seq = read_seqcount_begin(&t->vtime_seqcount); gtime = t->gtime; if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU) gtime += vtime_delta(t); } while (read_seqcount_retry(&t->vtime_seqcount, seq)); return gtime; } /* * Fetch cputime raw values from fields of task_struct and * add up the pending nohz execution time since the last * cputime snapshot. */ static void fetch_task_cputime(struct task_struct *t, cputime_t *u_dst, cputime_t *s_dst, cputime_t *u_src, cputime_t *s_src, cputime_t *udelta, cputime_t *sdelta) { unsigned int seq; unsigned long long delta; do { *udelta = 0; *sdelta = 0; seq = read_seqcount_begin(&t->vtime_seqcount); if (u_dst) *u_dst = *u_src; if (s_dst) *s_dst = *s_src; /* Task is sleeping, nothing to add */ if (t->vtime_snap_whence == VTIME_INACTIVE || is_idle_task(t)) continue; delta = vtime_delta(t); /* * Task runs either in user or kernel space, add pending nohz time to * the right place. */ if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) { *udelta = delta; } else { if (t->vtime_snap_whence == VTIME_SYS) *sdelta = delta; } } while (read_seqcount_retry(&t->vtime_seqcount, seq)); } void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime) { cputime_t udelta, sdelta; if (!vtime_accounting_enabled()) { if (utime) *utime = t->utime; if (stime) *stime = t->stime; return; } fetch_task_cputime(t, utime, stime, &t->utime, &t->stime, &udelta, &sdelta); if (utime) *utime += udelta; if (stime) *stime += sdelta; } void task_cputime_scaled(struct task_struct *t, cputime_t *utimescaled, cputime_t *stimescaled) { cputime_t udelta, sdelta; if (!vtime_accounting_enabled()) { if (utimescaled) *utimescaled = t->utimescaled; if (stimescaled) *stimescaled = t->stimescaled; return; } fetch_task_cputime(t, utimescaled, stimescaled, &t->utimescaled, &t->stimescaled, &udelta, &sdelta); if (utimescaled) *utimescaled += cputime_to_scaled(udelta); if (stimescaled) *stimescaled += cputime_to_scaled(sdelta); } #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */