Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760045AbZD1Khe (ORCPT ); Tue, 28 Apr 2009 06:37:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753373AbZD1KhZ (ORCPT ); Tue, 28 Apr 2009 06:37:25 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:58962 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752334AbZD1KhY (ORCPT ); Tue, 28 Apr 2009 06:37:24 -0400 Date: Tue, 28 Apr 2009 16:07:01 +0530 From: Bharata B Rao To: KOSAKI Motohiro Cc: LKML , Balaji Rao , Dhaval Giani , KAMEZAWA Hiroyuki , Peter Zijlstra , Balbir Singh , Ingo Molnar , Martin Schwidefsky , seto.hidetoshi@jp.fujitsu.com Subject: Re: [PATCH] cpuacct: VIRT_CPU_ACCOUNTING don't prevent percpu cputime count Message-ID: <20090428103701.GE3825@in.ibm.com> Reply-To: bharata@linux.vnet.ibm.com References: <20090428163509.EBCF.A69D9226@jp.fujitsu.com> <20090428075055.GD3825@in.ibm.com> <20090428165203.EBD5.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090428165203.EBD5.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 Content-Length: 1195 Lines: 29 On Tue, Apr 28, 2009 at 05:10:47PM +0900, KOSAKI Motohiro wrote: > > On Tue, Apr 28, 2009 at 04:38:51PM +0900, KOSAKI Motohiro wrote: > > > > On Tue, Apr 28, 2009 at 03:53:32PM +0900, KOSAKI Motohiro wrote: > > > > > > > BTW, did you observe any real problem with the percpu counter spinlock ? > > > > > > No. > > > I review percpu_counter() caller recently and it seems stragen usage. > > > > > > > I should have phrased the question better ... > > > > So have you found any performance degradation with any benchmarks/workloads > > on archs which define VIRT_CPU_ACCOUNTING due to percpu_counter spinlock > > being taken on every tick ? If the answer is no, don't you think we could > > wait before making the kind of change you are proposing ? > > maybe, I don't understand your point. My point is, let us not make this change if it is not a real problem that has been observed on archs which define VIRT_CPU_ACCOUNTING. Regards, Bharata. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/