Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758868AbZD2Cb1 (ORCPT ); Tue, 28 Apr 2009 22:31:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752298AbZD2CbS (ORCPT ); Tue, 28 Apr 2009 22:31:18 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:46553 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751918AbZD2CbS (ORCPT ); Tue, 28 Apr 2009 22:31:18 -0400 From: KOSAKI Motohiro To: bharata@linux.vnet.ibm.com Subject: Re: [PATCH] cpuacct: VIRT_CPU_ACCOUNTING don't prevent percpu cputime count Cc: kosaki.motohiro@jp.fujitsu.com, LKML , Balaji Rao , Dhaval Giani , KAMEZAWA Hiroyuki , Peter Zijlstra , Balbir Singh , Ingo Molnar , Martin Schwidefsky , seto.hidetoshi@jp.fujitsu.com In-Reply-To: <20090428103701.GE3825@in.ibm.com> References: <20090428165203.EBD5.A69D9226@jp.fujitsu.com> <20090428103701.GE3825@in.ibm.com> Message-Id: <20090429110629.4B05.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 [ja] Date: Wed, 29 Apr 2009 11:31:14 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1094 Lines: 29 > > > > > 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. It's nice joke. but not constructive. but another idea and another patch are always welcome. -- 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/