From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752552AbZCKCPZ (ORCPT ); Tue, 10 Mar 2009 22:15:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751438AbZCKCPM (ORCPT ); Tue, 10 Mar 2009 22:15:12 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:65484 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751162AbZCKCPL (ORCPT ); Tue, 10 Mar 2009 22:15:11 -0400 Message-ID: <49B71EB5.1030608@cn.fujitsu.com> Date: Wed, 11 Mar 2009 10:15:17 +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] cpuacct: reduce one NULL check in fast-path Content-Type: text/plain; charset=UTF-8 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 --- kernel/sched.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 9bb6d24..bc8a91e 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -9768,10 +9768,11 @@ 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 = percpu_ptr(ca->cpuusage, cpu); *cpuusage += cputime; - } + ca = ca->parent; + } while (ca); } struct cgroup_subsys cpuacct_subsys = { -- 1.5.4.rc3