From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936032Ab3DJNmv (ORCPT ); Wed, 10 Apr 2013 09:42:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59343 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576Ab3DJNmu (ORCPT ); Wed, 10 Apr 2013 09:42:50 -0400 Date: Wed, 10 Apr 2013 06:42:33 -0700 From: tip-bot for Li Zefan Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de, lizefan@huawei.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, lizefan@huawei.com In-Reply-To: <515536B7.6060602@huawei.com> References: <515536B7.6060602@huawei.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/cpuacct: Remove redundant NULL checks in cpuacct_acount_field() Git-Commit-ID: 5f40d804325e925409907e29f46ecb012090b6c2 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 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Wed, 10 Apr 2013 06:42:39 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5f40d804325e925409907e29f46ecb012090b6c2 Gitweb: http://git.kernel.org/tip/5f40d804325e925409907e29f46ecb012090b6c2 Author: Li Zefan AuthorDate: Fri, 29 Mar 2013 14:37:43 +0800 Committer: Ingo Molnar CommitDate: Wed, 10 Apr 2013 13:54:18 +0200 sched/cpuacct: Remove redundant NULL checks in cpuacct_acount_field() 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 Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/515536B7.6060602@huawei.com Signed-off-by: Ingo Molnar --- 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..b2f79ad1 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)