From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753218Ab3KAO2I (ORCPT ); Fri, 1 Nov 2013 10:28:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2996 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710Ab3KAO2F (ORCPT ); Fri, 1 Nov 2013 10:28:05 -0400 Message-ID: <5273BA58.6010404@redhat.com> Date: Fri, 01 Nov 2013 10:27:36 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Peter Zijlstra CC: Mel Gorman , mingo@kernel.org, prarit@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH -tip] fix race between stop_two_cpus and stop_cpus References: <20131031163144.0fd27457@annuminas.surriel.com> <20131101110825.GX2400@suse.de> <52739244.3060209@redhat.com> <20131101134424.GA32685@suse.de> <20131101142404.GG19466@laptop.lan> In-Reply-To: <20131101142404.GG19466@laptop.lan> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/01/2013 10:24 AM, Peter Zijlstra wrote: > On Fri, Nov 01, 2013 at 01:44:24PM +0000, Mel Gorman wrote: >> Ok, I see your point now but still wonder if this is too specialised >> for what we are trying to do. Could it have been done with a read-write >> semaphore with the global stop_cpus taking it for write and stop_two_cpus >> taking it for read? > > rwsem for read is still global state.. That said it should be fairly > easy to use lglock for this. I'll rewrite the patch using lglocks, that should make things more readable. -- All rights reversed