Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753358Ab2FEVhm (ORCPT ); Tue, 5 Jun 2012 17:37:42 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42430 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968Ab2FEVhk convert rfc822-to-8bit (ORCPT ); Tue, 5 Jun 2012 17:37:40 -0400 Message-ID: <1338932241.2749.62.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: Tue, 05 Jun 2012 23:37:21 +0200 In-Reply-To: <20120605212947.GA8686@linux.vnet.ibm.com> References: <87zk8iioam.fsf@rustcorp.com.au> <1338881971.28282.150.camel@twins> <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> 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: 936 Lines: 23 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'? 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. If you don't bring them down far enough to unplug, should you still be calling it hotplug? Ideally I think there'd be a file in your cpuset which if opened and written to will flush all pending bits (timers, workqueues, the lot) and return when this is done (and maybe provide O_ASYNC writes to not wait for completion). -- 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/