From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752276AbbJOJ27 (ORCPT ); Thu, 15 Oct 2015 05:28:59 -0400 Received: from terminus.zytor.com ([198.137.202.10]:46196 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751760AbbJOJ2y (ORCPT ); Thu, 15 Oct 2015 05:28:54 -0400 Date: Thu, 15 Oct 2015 02:27:39 -0700 From: tip-bot for Jason Low Message-ID: Cc: hpa@zytor.com, linux-kernel@vger.kernel.org, linux@horizon.com, tglx@linutronix.de, jason.low2@hp.com, mingo@kernel.org, peterz@infradead.org, dave@stgolabs.net, rostedt@goodmis.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com Reply-To: tglx@linutronix.de, hpa@zytor.com, linux@horizon.com, linux-kernel@vger.kernel.org, peterz@infradead.org, dave@stgolabs.net, jason.low2@hp.com, mingo@kernel.org, rostedt@goodmis.org, paulmck@linux.vnet.ibm.com, oleg@redhat.com, fweisbec@gmail.com In-Reply-To: <1444849677-29330-2-git-send-email-jason.low2@hp.com> References: <1444849677-29330-2-git-send-email-jason.low2@hp.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] posix_cpu_timer: Optimize fastpath_timer_check( ) Git-Commit-ID: 7c177d994eb9637302b79e80d331f48dfbe26368 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 7c177d994eb9637302b79e80d331f48dfbe26368 Gitweb: http://git.kernel.org/tip/7c177d994eb9637302b79e80d331f48dfbe26368 Author: Jason Low AuthorDate: Wed, 14 Oct 2015 12:07:53 -0700 Committer: Thomas Gleixner CommitDate: Thu, 15 Oct 2015 11:23:41 +0200 posix_cpu_timer: Optimize fastpath_timer_check() In fastpath_timer_check(), the task_cputime() function is always called to compute the utime and stime values. However, this is not necessary if there are no per-thread timers to check for. This patch modifies the code such that we compute the task_cputime values only when there are per-thread timers set. Signed-off-by: Jason Low Reviewed-by: Oleg Nesterov Reviewed-by: Frederic Weisbecker Reviewed-by: Davidlohr Bueso Reviewed-by: George Spelvin Cc: Paul E. McKenney Cc: Steven Rostedt Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1444849677-29330-2-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner --- kernel/time/posix-cpu-timers.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 892e3da..aa4b6f4 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1117,17 +1117,12 @@ static inline int task_cputime_expired(const struct task_cputime *sample, static inline int fastpath_timer_check(struct task_struct *tsk) { struct signal_struct *sig; - cputime_t utime, stime; - - task_cputime(tsk, &utime, &stime); if (!task_cputime_zero(&tsk->cputime_expires)) { - struct task_cputime task_sample = { - .utime = utime, - .stime = stime, - .sum_exec_runtime = tsk->se.sum_exec_runtime - }; + struct task_cputime task_sample; + task_cputime(tsk, &task_sample.utime, &task_sample.stime); + task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime; if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) return 1; }