From a19ff1a2cc9227f82e97836a8ee3e593f622eaf9 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 5 Jan 2017 18:11:47 +0100 Subject: [PATCH] sched/cputime, powerpc/vtime: Accumulate cputime and account only on tick/task switch Currently CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y accounts the cputime on any context boundary: irq entry/exit, guest entry/exit, context switch, etc... Calling functions such as account_system_time(), account_user_time() and such can be costly, especially if they are called on many fastpath such as twice per IRQ. Those functions do more than just accounting to kcpustat and task cputime. Depending on the config, some subsystems can perform unpleasant multiplications and divisions, among other things. So lets accumulate the cputime instead and delay the accounting on ticks and context switches only. Signed-off-by: Frederic Weisbecker Acked-by: Thomas Gleixner Cc: Benjamin Herrenschmidt Cc: Christian Borntraeger Cc: Fenghua Yu Cc: Heiko Carstens Cc: Linus Torvalds Cc: Martin Schwidefsky Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Rik van Riel Cc: Stanislaw Gruszka Cc: Tony Luck Cc: Wanpeng Li Link: http://lkml.kernel.org/r/1483636310-6557-8-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/time.c | 120 ++++++++++++++++++++++++------------- 1 file changed, 77 insertions(+), 43 deletions(-) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 714313ebf030..4255e6930ac1 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -280,17 +280,10 @@ void accumulate_stolen_time(void) static inline u64 calculate_stolen_time(u64 stop_tb) { - u64 stolen = 0; - struct cpu_accounting_data *acct = &local_paca->accounting; - - if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) { - stolen = scan_dispatch_log(stop_tb); - acct->stime -= stolen; - } + if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) + return scan_dispatch_log(stop_tb); - stolen += acct->steal_time; - acct->steal_time = 0; - return stolen; + return 0; } #else /* CONFIG_PPC_SPLPAR */ @@ -306,27 +299,26 @@ static inline u64 calculate_stolen_time(u64 stop_tb) * or soft irq state. */ static unsigned long vtime_delta(struct task_struct *tsk, - unsigned long *sys_scaled, - unsigned long *stolen) + unsigned long *stime_scaled, + unsigned long *steal_time) { unsigned long now, nowscaled, deltascaled; - unsigned long udelta, delta, user_scaled; + unsigned long stime; + unsigned long utime, utime_scaled; struct cpu_accounting_data *acct = get_accounting(tsk); WARN_ON_ONCE(!irqs_disabled()); now = mftb(); nowscaled = read_spurr(now); - acct->stime += now - acct->starttime; + stime = now - acct->starttime; acct->starttime = now; deltascaled = nowscaled - acct->startspurr; acct->startspurr = nowscaled; - *stolen = calculate_stolen_time(now); + *steal_time = calculate_stolen_time(now); - delta = acct->stime; - acct->stime = 0; - udelta = acct->utime - acct->utime_sspurr; + utime = acct->utime - acct->utime_sspurr; acct->utime_sspurr = acct->utime; /* @@ -339,39 +331,54 @@ static unsigned long vtime_delta(struct task_struct *tsk, * the user ticks get saved up in paca->user_time_scaled to be * used by account_process_tick. */ - *sys_scaled = delta; - user_scaled = udelta; - if (deltascaled != delta + udelta) { - if (udelta) { - *sys_scaled = deltascaled * delta / (delta + udelta); - user_scaled = deltascaled - *sys_scaled; + *stime_scaled = stime; + utime_scaled = utime; + if (deltascaled != stime + utime) { + if (utime) { + *stime_scaled = deltascaled * stime / (stime + utime); + utime_scaled = deltascaled - *stime_scaled; } else { - *sys_scaled = deltascaled; + *stime_scaled = deltascaled; } } - acct->utime_scaled += user_scaled; + acct->utime_scaled += utime_scaled; - return delta; + return stime; } void vtime_account_system(struct task_struct *tsk) { - unsigned long delta, sys_scaled, stolen; + unsigned long stime, stime_scaled, steal_time; + struct cpu_accounting_data *acct = get_accounting(tsk); + + stime = vtime_delta(tsk, &stime_scaled, &steal_time); + + stime -= min(stime, steal_time); + acct->steal_time += steal_time; - delta = vtime_delta(tsk, &sys_scaled, &stolen); - account_system_time(tsk, 0, delta); - tsk->stimescaled += sys_scaled; - if (stolen) - account_steal_time(stolen); + if ((tsk->flags & PF_VCPU) && !irq_count()) { + acct->gtime += stime; + acct->utime_scaled += stime_scaled; + } else { + if (hardirq_count()) + acct->hardirq_time += stime; + else if (in_serving_softirq()) + acct->softirq_time += stime; + else + acct->stime += stime; + + acct->stime_scaled += stime_scaled; + } } EXPORT_SYMBOL_GPL(vtime_account_system); void vtime_account_idle(struct task_struct *tsk) { - unsigned long delta, sys_scaled, stolen; + unsigned long stime, stime_scaled, steal_time; + struct cpu_accounting_data *acct = get_accounting(tsk); - delta = vtime_delta(tsk, &sys_scaled, &stolen); - account_idle_time(delta + stolen); + stime = vtime_delta(tsk, &stime_scaled, &steal_time); + acct->idle_time += stime + steal_time; } /* @@ -385,16 +392,45 @@ void vtime_account_idle(struct task_struct *tsk) */ void vtime_account_user(struct task_struct *tsk) { - cputime_t utime, utimescaled; struct cpu_accounting_data *acct = get_accounting(tsk); - utime = acct->utime; - utimescaled = acct->utime_scaled; + if (acct->utime) + account_user_time(tsk, acct->utime); + + if (acct->utime_scaled) + tsk->utimescaled += acct->utime_scaled; + + if (acct->gtime) + account_guest_time(tsk, acct->gtime); + + if (acct->steal_time) + account_steal_time(acct->steal_time); + + if (acct->idle_time) + account_idle_time(acct->idle_time); + + if (acct->stime) + account_system_index_time(tsk, acct->stime, CPUTIME_SYSTEM); + + if (acct->stime_scaled) + tsk->stimescaled += acct->stime_scaled; + + if (acct->hardirq_time) + account_system_index_time(tsk, acct->hardirq_time, CPUTIME_IRQ); + + if (acct->softirq_time) + account_system_index_time(tsk, acct->softirq_time, CPUTIME_SOFTIRQ); + acct->utime = 0; acct->utime_scaled = 0; acct->utime_sspurr = 0; - account_user_time(tsk, utime); - tsk->utimescaled += utimescaled; + acct->gtime = 0; + acct->steal_time = 0; + acct->idle_time = 0; + acct->stime = 0; + acct->stime_scaled = 0; + acct->hardirq_time = 0; + acct->softirq_time = 0; } #ifdef CONFIG_PPC32 @@ -409,8 +445,6 @@ void arch_vtime_task_switch(struct task_struct *prev) acct->starttime = get_accounting(prev)->starttime; acct->startspurr = get_accounting(prev)->startspurr; - acct->stime = 0; - acct->utime = 0; } #endif /* CONFIG_PPC32 */ -- 2.20.1