From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759143Ab2BKE1M (ORCPT ); Fri, 10 Feb 2012 23:27:12 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:33597 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753728Ab2BKE1J (ORCPT ); Fri, 10 Feb 2012 23:27:09 -0500 Message-ID: <4F35EE11.5010202@linux.vnet.ibm.com> Date: Sat, 11 Feb 2012 09:56:57 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux i686; rv:9.0) Gecko/20111222 Thunderbird/9.0 MIME-Version: 1.0 To: Peter Zijlstra CC: "Rafael J. Wysocki" , Alan Stern , paulmck@linux.vnet.ibm.com, Ingo Molnar , paul@paulmenage.org, tj@kernel.org, frank.rowand@am.sony.com, pjt@google.com, tglx@linutronix.de, lizf@cn.fujitsu.com, prashanth@linux.vnet.ibm.com, vatsa@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "akpm@linux-foundation.org" Subject: Re: [PATCH 0/4] CPU hotplug, cpusets: Fix CPU online handling related to cpusets References: <201202102339.02702.rjw@sisk.pl> <1328926042.2476.3.camel@laptop> In-Reply-To: <1328926042.2476.3.camel@laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit x-cbid: 12021104-2000-0000-0000-00000660749C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2012 07:37 AM, Peter Zijlstra wrote: > On Fri, 2012-02-10 at 23:39 +0100, Rafael J. Wysocki wrote: >> >>> I don't see why not. Presumably no CPUs will be added or removed while >>> the system is asleep. >> >> ACPI explicitly forbids that level of hardware reconfiguration in a sleep >> state (even in S4), AFAICS. Still, people may try to do that ... > > I'm ok with breaking that :-) If its really really important to someone > we (him most likely) could fix it by detecting the topology changed over > the suspend and do a fixup. Assuming it actually gets that far. > > Srivatsa, wanna give this (the proposal to not modify cpusets on > CPU_TASKS_FROZEN) a try? > Sure! After you pointed out that CPU Hotplug is destructive in general and hence it is not a good idea to put back online CPUs to cpusets, the next thing I thought of trying was a special case handling for suspend/resume alone, IOW, not calling the cpuset update upon CPU_TASKS_FROZEN. So, yes, I'll write up a patch for that and post it soon :-) Regards, Srivatsa S. Bhat