Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752549AbcLFCc4 (ORCPT ); Mon, 5 Dec 2016 21:32:56 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:34644 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752257AbcLFCco (ORCPT ); Mon, 5 Dec 2016 21:32:44 -0500 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Tony Luck , Wanpeng Li , Peter Zijlstra , Michael Ellerman , Heiko Carstens , Benjamin Herrenschmidt , Thomas Gleixner , Paul Mackerras , Ingo Molnar , Fenghua Yu , Rik van Riel , Martin Schwidefsky , Stanislaw Gruszka Subject: [PATCH 07/10] powerpc/vtime: Accumulate cputime and account only on tick/task switch Date: Tue, 6 Dec 2016 03:32:20 +0100 Message-Id: <1480991543-6557-8-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1480991543-6557-1-git-send-email-fweisbec@gmail.com> References: <1480991543-6557-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6709 Lines: 226 Currently CONFIG_VIRT_CPU_ACCOUNTING_NATIVE 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. Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Heiko Carstens Cc: Martin Schwidefsky Cc: Tony Luck Cc: Fenghua Yu Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Stanislaw Gruszka Cc: Wanpeng Li Signed-off-by: Frederic Weisbecker --- 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 9625fec..093588a 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)) + return scan_dispatch_log(stop_tb); - if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) { - stolen = scan_dispatch_log(stop_tb); - acct->stime -= stolen; - } - - 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); - delta = vtime_delta(tsk, &sys_scaled, &stolen); - account_system_time(tsk, 0, delta); - tsk->stimescaled += sys_scaled; - if (stolen) - account_steal_time(stolen); + stime = vtime_delta(tsk, &stime_scaled, &steal_time); + + stime -= min(stime, steal_time); + acct->steal_time += steal_time; + + 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 */ -- 2.7.4