From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751993Ab3C1EOt (ORCPT ); Thu, 28 Mar 2013 00:14:49 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:35405 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751898Ab3C1EOs (ORCPT ); Thu, 28 Mar 2013 00:14:48 -0400 Message-ID: <5153C35F.10706@huawei.com> Date: Thu, 28 Mar 2013 12:13:19 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Ingo Molnar CC: Peter Zijlstra , LKML Subject: [PATCH 6/7] cpuacct: Remove redundant NULL checks in cpuacct_acount_field() References: <5153C2D6.7050103@huawei.com> In-Reply-To: <5153C2D6.7050103@huawei.com> Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.68.215] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a micro optimazation for a hot path. - We don't need to check if @ca returned from task_ca() is NULL. - We don't need to check if @ca returned from parent_ca() is NULL. Signed-off-by: Li Zefan --- kernel/sched/cpuacct.c | 4 ++-- kernel/sched/cpuacct.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index b2aaaba..071ae8d 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -237,10 +237,10 @@ void cpuacct_account_field(struct task_struct *p, int index, u64 val) rcu_read_lock(); ca = task_ca(p); - while (ca && (ca != &root_cpuacct)) { + while (ca != &root_cpuacct) { kcpustat = this_cpu_ptr(ca->cpustat); kcpustat->cpustat[index] += val; - ca = parent_ca(ca); + ca = __parent_ca(ca); } rcu_read_unlock(); } diff --git a/kernel/sched/cpuacct.h b/kernel/sched/cpuacct.h index 45c1682..b2f79ad 100644 --- a/kernel/sched/cpuacct.h +++ b/kernel/sched/cpuacct.h @@ -34,6 +34,11 @@ static inline struct cpuacct *task_ca(struct task_struct *tsk) struct cpuacct, css); } +static inline struct cpuacct *__parent_ca(struct cpuacct *ca) +{ + return cgroup_ca(ca->css.cgroup->parent); +} + static inline struct cpuacct *parent_ca(struct cpuacct *ca) { if (!ca->css.cgroup->parent) -- 1.8.0.2