Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752628AbZKZFtC (ORCPT ); Thu, 26 Nov 2009 00:49:02 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752221AbZKZFtB (ORCPT ); Thu, 26 Nov 2009 00:49:01 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:34848 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752179AbZKZFtA (ORCPT ); Thu, 26 Nov 2009 00:49:00 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Message-ID: <4B0E16AE.906@jp.fujitsu.com> Date: Thu, 26 Nov 2009 14:48:30 +0900 From: Hidetoshi Seto User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: Stanislaw Gruszka , Ingo Molnar , Peter Zijlstra , Spencer Candland , Oleg Nesterov , Balbir Singh , =?ISO-8859-1?Q?Am=E9rico_Wang?= Subject: [PATCH -tip 1/3] introduce task_times() to replace task_{u,s}time() pair References: <4B061E9A.8040100@jp.fujitsu.com> <20091123102806.GD25978@dhcp-lab-161.englab.brq.redhat.com> <4B0B714C.9080607@jp.fujitsu.com> <4B0B8683.6020104@jp.fujitsu.com> In-Reply-To: <4B0B8683.6020104@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5333 Lines: 181 Functions task_{u,s}time() are called in pair in almost all cases. However task_stime() is implemented to call task_utime() from its inside, so such paired calls run task_utime() twice. It means we do heavy divisions (div_u64 + do_div) twice to get utime and stime which can be obtained at same time by one set of divisions. This patch introduces a function task_times(*tsk, *utime, *stime) to retrieve utime and stime at once in better, optimized way. Signed-off-by: Hidetoshi Seto --- fs/proc/array.c | 3 +- include/linux/sched.h | 1 + kernel/exit.c | 7 ++++- kernel/sched.c | 55 +++++++++++++++++++++++++++++++----------------- kernel/sys.c | 3 +- 5 files changed, 43 insertions(+), 26 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index e209f64..330deda 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -535,8 +535,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, if (!whole) { min_flt = task->min_flt; maj_flt = task->maj_flt; - utime = task_utime(task); - stime = task_stime(task); + task_times(task, &utime, &stime); gtime = task_gtime(task); } diff --git a/include/linux/sched.h b/include/linux/sched.h index 78ba664..fe6ae15 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1723,6 +1723,7 @@ static inline void put_task_struct(struct task_struct *t) extern cputime_t task_utime(struct task_struct *p); extern cputime_t task_stime(struct task_struct *p); extern cputime_t task_gtime(struct task_struct *p); +extern void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st); /* * Per process flags diff --git a/kernel/exit.c b/kernel/exit.c index e61891f..a19e429 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -91,6 +91,8 @@ static void __exit_signal(struct task_struct *tsk) if (atomic_dec_and_test(&sig->count)) posix_cpu_timers_exit_group(tsk); else { + cputime_t utime, stime; + /* * If there is any task waiting for the group exit * then notify it: @@ -110,8 +112,9 @@ static void __exit_signal(struct task_struct *tsk) * We won't ever get here for the group leader, since it * will have been the last reference on the signal_struct. */ - sig->utime = cputime_add(sig->utime, task_utime(tsk)); - sig->stime = cputime_add(sig->stime, task_stime(tsk)); + task_times(tsk, &utime, &stime); + sig->utime = cputime_add(sig->utime, utime); + sig->stime = cputime_add(sig->stime, stime); sig->gtime = cputime_add(sig->gtime, task_gtime(tsk)); sig->min_flt += tsk->min_flt; sig->maj_flt += tsk->maj_flt; diff --git a/kernel/sched.c b/kernel/sched.c index a57c6ae..4d5e1a2 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5155,6 +5155,14 @@ cputime_t task_stime(struct task_struct *p) { return p->stime; } + +void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) +{ + if (ut) + *ut = task_utime(p); + if (st) + *st = task_stime(p); +} #else #ifndef nsecs_to_cputime @@ -5162,41 +5170,48 @@ cputime_t task_stime(struct task_struct *p) msecs_to_cputime(div_u64((__nsecs), NSEC_PER_MSEC)) #endif -cputime_t task_utime(struct task_struct *p) +void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) { - cputime_t utime = p->utime, total = utime + p->stime; - u64 temp; + cputime_t rtime, utime = p->utime, total = utime + p->stime; /* * Use CFS's precise accounting: */ - temp = (u64)nsecs_to_cputime(p->se.sum_exec_runtime); + rtime = nsecs_to_cputime(p->se.sum_exec_runtime); if (total) { - temp *= utime; + u64 temp; + + temp = (u64)(rtime * utime); do_div(temp, total); - } - utime = (cputime_t)temp; + utime = (cputime_t)temp; + } else + utime = rtime; + /* + * Compare with previous values, to keep monotonicity: + */ p->prev_utime = max(p->prev_utime, utime); - return p->prev_utime; + p->prev_stime = max(p->prev_stime, rtime - p->prev_utime); + + if (ut) + *ut = p->prev_utime; + if (st) + *st = p->prev_stime; +} + +cputime_t task_utime(struct task_struct *p) +{ + cputime_t utime; + task_times(p, &utime, NULL); + return utime; } cputime_t task_stime(struct task_struct *p) { cputime_t stime; - - /* - * Use CFS's precise accounting. (we subtract utime from - * the total, to make sure the total observed by userspace - * grows monotonically - apps rely on that): - */ - stime = nsecs_to_cputime(p->se.sum_exec_runtime) - task_utime(p); - - if (stime >= 0) - p->prev_stime = max(p->prev_stime, stime); - - return p->prev_stime; + task_times(p, NULL, &stime); + return stime; } #endif diff --git a/kernel/sys.c b/kernel/sys.c index 255475d..b6caf1e 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1344,8 +1344,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r) utime = stime = cputime_zero; if (who == RUSAGE_THREAD) { - utime = task_utime(current); - stime = task_stime(current); + task_times(current, &utime, &stime); accumulate_thread_rusage(p, r); maxrss = p->signal->maxrss; goto out; -- 1.6.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/