Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184Ab2FFMRj (ORCPT ); Wed, 6 Jun 2012 08:17:39 -0400 Received: from casper.infradead.org ([85.118.1.10]:34851 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752588Ab2FFMRi convert rfc822-to-8bit (ORCPT ); Wed, 6 Jun 2012 08:17:38 -0400 Message-ID: <1338985041.2749.107.camel@twins> Subject: Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi From: Peter Zijlstra To: paulmck@linux.vnet.ibm.com Cc: Thomas Gleixner , "Luck, Tony" , "Yu, Fenghua" , Rusty Russell , Ingo Molnar , H Peter Anvin , "Siddha, Suresh B" , "Mallick, Asit K" , Arjan Dan De Ven , linux-kernel , x86 , linux-pm , "Srivatsa S. Bhat" Date: Wed, 06 Jun 2012 14:17:21 +0200 In-Reply-To: <20120605220059.GV2388@linux.vnet.ibm.com> References: <3E5A0FA7E9CA944F9D5414FEC6C7122007727023@ORSMSX105.amr.corp.intel.com> <1338912565.2749.9.camel@twins> <3E5A0FA7E9CA944F9D5414FEC6C7122007728081@ORSMSX105.amr.corp.intel.com> <1338913190.2749.10.camel@twins> <3908561D78D1C84285E8C5FCA982C28F19300965@ORSMSX104.amr.corp.intel.com> <1338918625.2749.29.camel@twins> <1338925756.2749.36.camel@twins> <20120605212947.GA8686@linux.vnet.ibm.com> <1338932241.2749.62.camel@twins> <20120605220059.GV2388@linux.vnet.ibm.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1301 Lines: 29 On Tue, 2012-06-05 at 15:00 -0700, Paul E. McKenney wrote: > On Tue, Jun 05, 2012 at 11:37:21PM +0200, Peter Zijlstra wrote: > > On Tue, 2012-06-05 at 14:29 -0700, Paul E. McKenney wrote: > > > OK, I'll bite... Why not just use CPU hotplug to expel the timers? > > > > Currently? Can you say: 'kstopmachine'? > > So if CPU hotplug (or whatever you want to call it) stops using > kstopmachine, you are OK with it? It would be much better, still not ideal though. > > But its also a question of interface and naming. Do you want to have to > > iterate all cpus in your isolated set, do you want to bring them down > > far enough to physically unplug. Ideally no to both. > > For many use cases, it is indeed not necessary to get to a point where > the CPUs could be physically removed from the system. But CPU-failure > use cases would need the CPU to be fully deactivated. And many of the > hardware guys tell me that the CPU-failure case will be getting more > common, though I sure hope that they are wrong. Uhm, yeah, that doesn't sound right. -- 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/