From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932773AbXCYJFd (ORCPT ); Sun, 25 Mar 2007 05:05:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933215AbXCYJFd (ORCPT ); Sun, 25 Mar 2007 05:05:33 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:47815 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932773AbXCYJFc (ORCPT ); Sun, 25 Mar 2007 05:05:32 -0400 Date: Sun, 25 Mar 2007 11:04:53 +0200 From: Ingo Molnar To: Con Kolivas Cc: linux list , malc , zwane@infradead.org, ck list , Andrew Morton , Thomas Gleixner Subject: Re: [patch] sched: accurate user accounting Message-ID: <20070325090453.GA30423@elte.hu> References: <200703251159.03616.kernel@kolivas.org> <20070325075134.GA14453@elte.hu> <200703251839.24148.kernel@kolivas.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200703251839.24148.kernel@kolivas.org> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Con Kolivas wrote: > > +/* > > + * Some helpers for converting nanosecond timing to jiffy resolution > > + */ > > +#define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) > > +#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) > > + > > This hunk is already in mainline so it will be double defined now. yeah. Updated patch below. Ingo ----------------------> Subject: [patch] sched: accurate user accounting From: Con Kolivas Currently we only do cpu accounting to userspace based on what is actually happening precisely on each tick. The accuracy of that accounting gets progressively worse the lower HZ is. As we already keep accounting of nanosecond resolution we can accurately track user cpu, nice cpu and idle cpu if we move the accounting to update_cpu_clock with a nanosecond cpu_usage_stat entry. This increases overhead slightly but avoids the problem of tick aliasing errors making accounting unreliable. Signed-off-by: Con Kolivas Signed-off-by: Ingo Molnar --- include/linux/kernel_stat.h | 3 ++ include/linux/sched.h | 2 - kernel/sched.c | 46 +++++++++++++++++++++++++++++++++++++++++--- kernel/timer.c | 5 +--- 4 files changed, 49 insertions(+), 7 deletions(-) Index: linux/include/linux/kernel_stat.h =================================================================== --- linux.orig/include/linux/kernel_stat.h +++ linux/include/linux/kernel_stat.h @@ -16,11 +16,14 @@ struct cpu_usage_stat { cputime64_t user; + cputime64_t user_ns; cputime64_t nice; + cputime64_t nice_ns; cputime64_t system; cputime64_t softirq; cputime64_t irq; cputime64_t idle; + cputime64_t idle_ns; cputime64_t iowait; cputime64_t steal; }; Index: linux/include/linux/sched.h =================================================================== --- linux.orig/include/linux/sched.h +++ linux/include/linux/sched.h @@ -882,7 +882,7 @@ struct task_struct { int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ unsigned long rt_priority; - cputime_t utime, stime; + cputime_t utime, utime_ns, stime; unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ Index: linux/kernel/sched.c =================================================================== --- linux.orig/kernel/sched.c +++ linux/kernel/sched.c @@ -3017,8 +3017,50 @@ EXPORT_PER_CPU_SYMBOL(kstat); static inline void update_cpu_clock(struct task_struct *p, struct rq *rq, unsigned long long now) { - p->sched_time += now - p->last_ran; + struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; + cputime64_t time_diff = now - p->last_ran; + + p->sched_time += time_diff; p->last_ran = rq->most_recent_timestamp = now; + if (p != rq->idle) { + cputime_t utime_diff = time_diff; + + if (TASK_NICE(p) > 0) { + cpustat->nice_ns = cputime64_add(cpustat->nice_ns, + time_diff); + if (NS_TO_JIFFIES(cpustat->nice_ns) > 1) { + cpustat->nice_ns = + cputime64_sub(cpustat->nice_ns, + JIFFIES_TO_NS(1)); + cpustat->nice = + cputime64_add(cpustat->nice, 1); + } + } else { + cpustat->user_ns = cputime64_add(cpustat->user_ns, + time_diff); + if (NS_TO_JIFFIES(cpustat->user_ns) > 1) { + cpustat->user_ns = + cputime64_sub(cpustat->user_ns, + JIFFIES_TO_NS(1)); + cpustat ->user = + cputime64_add(cpustat->user, 1); + } + } + p->utime_ns = cputime_add(p->utime_ns, utime_diff); + if (NS_TO_JIFFIES(p->utime_ns) > 1) { + p->utime_ns = cputime_sub(p->utime_ns, + JIFFIES_TO_NS(1)); + p->utime = cputime_add(p->utime, + jiffies_to_cputime(1)); + } + } else { + cpustat->idle_ns = cputime64_add(cpustat->idle_ns, time_diff); + if (NS_TO_JIFFIES(cpustat->idle_ns) > 1) { + cpustat->idle_ns = cputime64_sub(cpustat->idle_ns, + JIFFIES_TO_NS(1)); + cpustat->idle = cputime64_add(cpustat->idle, 1); + } + } } /* @@ -3104,8 +3146,6 @@ void account_system_time(struct task_str cpustat->system = cputime64_add(cpustat->system, tmp); else if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, tmp); - else - cpustat->idle = cputime64_add(cpustat->idle, tmp); /* Account for system time used */ acct_update_integrals(p); } Index: linux/kernel/timer.c =================================================================== --- linux.orig/kernel/timer.c +++ linux/kernel/timer.c @@ -1196,10 +1196,9 @@ void update_process_times(int user_tick) int cpu = smp_processor_id(); /* Note: this timer irq context must be accounted for as well. */ - if (user_tick) - account_user_time(p, jiffies_to_cputime(1)); - else + if (!user_tick) account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); + /* User time is accounted for in update_cpu_clock in sched.c */ run_local_timers(); if (rcu_pending(cpu)) rcu_check_callbacks(cpu, user_tick);