From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759697AbZELKLT (ORCPT ); Tue, 12 May 2009 06:11:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754214AbZELKLG (ORCPT ); Tue, 12 May 2009 06:11:06 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:53534 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750886AbZELKLD (ORCPT ); Tue, 12 May 2009 06:11:03 -0400 Date: Tue, 12 May 2009 15:40:57 +0530 From: Balbir Singh To: KOSAKI Motohiro Cc: Ingo Molnar , mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, schwidefsky@de.ibm.com, balajirrao@gmail.com, dhaval@linux.vnet.ibm.com, bharata@linux.vnet.ibm.com, tglx@linutronix.de, kamezawa.hiroyu@jp.fujitsu.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:sched/core] sched: cpuacct: Use bigger percpu counter batch values for stats counters Message-ID: <20090512101057.GD6351@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090511150709.GA23787@elte.hu> <20090512185836.D635.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090512185836.D635.A69D9226@jp.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 * KOSAKI Motohiro [2009-05-12 19:01:25]: > > > > * tip-bot for KOSAKI Motohiro wrote: > > > > > Commit-ID: 50fbed3bb72cbe38a665512771a91a96d028de46 > > > Gitweb: http://git.kernel.org/tip/50fbed3bb72cbe38a665512771a91a96d028de46 > > > Author: KOSAKI Motohiro > > > AuthorDate: Sat, 9 May 2009 19:14:58 +0900 > > > Committer: Ingo Molnar > > > CommitDate: Mon, 11 May 2009 14:32:57 +0200 > > > > > > sched: cpuacct: Use bigger percpu counter batch values for stats counters > > > > -tip testing found a build failure with this patch: > > > > kernel/sched.c:9278: error: ?$B!Fpercpu_counter_batch?$B!G undeclared (first use in this function) > > kernel/sched.c:9278: error: (Each undeclared identifier is reported only once > > kernel/sched.c:9278: error: for each function it appears in.) > > Oh, my fault again. Good catch! > > > > Changelog: > since V5 > - fix build error when UP > > since V4 > - move cpuacct_batch initialization into sched_init() > > since V3 > - rewirte patch description (thanks Bharata!) > - append read_mostly to cpuacct_batch > - cpuacct_batch is initialized by sched_init() > > since v2 > - revert using percpu_counter_sum() > > since v1 > - use percpu_counter_sum() instead percpu_counter_read() > > > --------------------------------------------------------- > Subject: [PATCH v6] cpuacct: Use bigger percpu counter batch values for stats counters on archs that have VIRT_CPU_ACCOUNTING=y > > percpu counters used to accumulate statistics in cpuacct controller use > the default batch value [max(2*nr_cpus, 32)] which can be too small for > archs that define VIRT_CPU_ACCOUNTING. In such archs, a tick could result in > cputime updates in the range of thousands. As a result, cpuacct_update_stats() > would end up acquiring the percpu counter spinlock on every tick which > is not good for performance. > > Let those architectures to have a bigger batch threshold so that percpu counter > spinlock isn't taken on every tick. This change doesn't affect the archs which > don't define VIRT_CPU_ACCOUNTING and they continue to have the default > percpu counter batch value. > > Cc: Balaji Rao > Cc: Dhaval Giani > Cc: KAMEZAWA Hiroyuki > Cc: Peter Zijlstra > Cc: Balbir Singh > Cc: Ingo Molnar > Cc: Martin Schwidefsky > Signed-off-by: Bharata B Rao > Signed-off-by: KOSAKI Motohiro > --- > kernel/sched.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > Index: b/kernel/sched.c > =================================================================== > --- a/kernel/sched.c 2009-05-12 13:12:59.000000000 +0900 > +++ b/kernel/sched.c 2009-05-12 13:28:53.000000000 +0900 > @@ -870,6 +870,8 @@ static __read_mostly int scheduler_runni > */ > int sysctl_sched_rt_runtime = 950000; > > +static __read_mostly s32 cpuacct_batch; > + > static inline u64 global_rt_period(void) > { > return (u64)sysctl_sched_rt_period * NSEC_PER_USEC; > @@ -9284,6 +9286,10 @@ void __init sched_init(void) > > perf_counter_init(); > > +#ifdef CONFIGCONFIG_SMP > + cpuacct_batch = jiffies_to_cputime(percpu_counter_batch); > +#endif Slow down and compile patches before sending them out.. please. That is a basic expectation if you expect it to be merged. -- Balbir