From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754162AbZEIKPU (ORCPT ); Sat, 9 May 2009 06:15:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751228AbZEIKPE (ORCPT ); Sat, 9 May 2009 06:15:04 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:56368 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750936AbZEIKPB (ORCPT ); Sat, 9 May 2009 06:15:01 -0400 From: KOSAKI Motohiro To: KOSAKI Motohiro Subject: Re: [PATCH v3] cpuacct: VIRT_CPU_ACCOUNTING don't prevent percpu cputime count Cc: kosaki.motohiro@jp.fujitsu.com, Peter Zijlstra , Ingo Molnar , LKML , Bharata B Rao , Balaji Rao , Dhaval Giani , KAMEZAWA Hiroyuki , Balbir Singh , Martin Schwidefsky In-Reply-To: <20090509185145.3AD2.A69D9226@jp.fujitsu.com> References: <1241861925.6316.112.camel@laptop> <20090509185145.3AD2.A69D9226@jp.fujitsu.com> Message-Id: <20090509191430.3AD5.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Sat, 9 May 2009 19:14:58 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > On Sat, 2009-05-09 at 18:26 +0900, KOSAKI Motohiro wrote: > > > > > > Index: b/kernel/sched.c > > > =================================================================== > > > --- a/kernel/sched.c 2009-05-09 16:48:08.000000000 +0900 > > > +++ b/kernel/sched.c 2009-05-09 18:16:00.000000000 +0900 > > > @@ -824,8 +824,12 @@ static struct file_operations sched_feat > > > .release = single_release, > > > }; > > > > > > +static __read_mostly s32 cpuacct_batch; > > > + > > > static __init int sched_init_debug(void) > > > { > > > + cpuacct_batch = jiffies_to_cputime(percpu_counter_batch); > > > + > > > debugfs_create_file("sched_features", 0644, NULL, NULL, > > > &sched_feat_fops); > > > > I'm pretty user you can select cpu accounting without SCHED_DEBUG... > > Grr, yes, it's idiot ;) > I'll fix it soon. Done. Changelog: 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_debug() since v2 - revert using percpu_counter_sum() since v1 - use percpu_counter_sum() instead percpu_counter_read() --------------------------------------------------------- Subject: [PATCH v5] 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 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) Index: b/kernel/sched.c =================================================================== --- a/kernel/sched.c 2009-05-09 16:48:08.000000000 +0900 +++ b/kernel/sched.c 2009-05-09 18:57:35.000000000 +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 +9286,8 @@ void __init sched_init(void) perf_counter_init(); + cpuacct_batch = jiffies_to_cputime(percpu_counter_batch); + scheduler_running = 1; } @@ -10457,7 +10461,8 @@ static void cpuacct_update_stats(struct ca = task_ca(tsk); do { - percpu_counter_add(&ca->cpustat[idx], val); + __percpu_counter_add(&ca->cpustat[idx], val, cpuacct_batch); + ca = ca->parent; } while (ca); rcu_read_unlock();