From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754732AbZBZIh0 (ORCPT ); Thu, 26 Feb 2009 03:37:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752469AbZBZIhN (ORCPT ); Thu, 26 Feb 2009 03:37:13 -0500 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:59329 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752454AbZBZIhM (ORCPT ); Thu, 26 Feb 2009 03:37:12 -0500 Date: Thu, 26 Feb 2009 14:07:02 +0530 From: Balbir Singh To: Li Zefan Cc: Ingo Molnar , Peter Zijlstra , Paul Menage , LKML Subject: Re: [PATCH] cpuacct: add a branch prediction Message-ID: <20090226083702.GI11421@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <49A6475F.4000502@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <49A6475F.4000502@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Li Zefan [2009-02-26 15:40:15]: > cpuacct_charge() is in fast-path, and checking of !cpuacct_susys.active > always returns false after cpuacct has been initialized at system boot. > > Signed-off-by: Li Zefan > --- > kernel/sched.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c > index 410eec4..fd2f7fc 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -9589,7 +9589,7 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime) > struct cpuacct *ca; > int cpu; > > - if (!cpuacct_subsys.active) > + if (unlikely(!cpuacct_subsys.active)) What happens if most distros make cpuacct_subsys active? Can we decide on unlikely depending on how the system is configured? -- Balbir