From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754766AbZCLBXS (ORCPT ); Wed, 11 Mar 2009 21:23:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752210AbZCLBXB (ORCPT ); Wed, 11 Mar 2009 21:23:01 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:55338 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752054AbZCLBXA (ORCPT ); Wed, 11 Mar 2009 21:23:00 -0400 Message-ID: <49B863F5.2060400@cn.fujitsu.com> Date: Thu, 12 Mar 2009 09:23:01 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar CC: Peter Zijlstra , Paul Menage , Balbir Singh , Bharata B Rao , LKML Subject: [PATCH -tip] cpuacct: reduce one NULL check in fast-path References: <49B71EB5.1030608@cn.fujitsu.com> <20090311094744.GB13543@elte.hu> In-Reply-To: <20090311094744.GB13543@elte.hu> 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 In cpuacct_charge(), task_ca() will never return NULL, so change for(...) to do{}while(...) to save one NULL check. Signed-off-by: Li Zefan --- rebased on tip tree --- kernel/sched.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index d40964b..c167f38 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -9867,10 +9867,11 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime) cpu = task_cpu(tsk); ca = task_ca(tsk); - for (; ca; ca = ca->parent) { + do { u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); *cpuusage += cputime; - } + ca = ca->parent; + } while (ca); } struct cgroup_subsys cpuacct_subsys = { -- 1.5.4.rc3