From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752286Ab2GZLL2 (ORCPT ); Thu, 26 Jul 2012 07:11:28 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:36530 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882Ab2GZLL0 (ORCPT ); Thu, 26 Jul 2012 07:11:26 -0400 Message-ID: <501125D3.9050705@linux.vnet.ibm.com> Date: Thu, 26 Jul 2012 16:41:15 +0530 From: "Srivatsa S. Bhat" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Thomas Gleixner CC: Alan Stern , mingo@kernel.org, peterz@infradead.org, rusty@rustcorp.com.au, paulmck@linux.vnet.ibm.com, namhyung@kernel.org, tj@kernel.org, rjw@sisk.pl, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Arjan van de Ven Subject: Re: [RFC PATCH 0/6] CPU hotplug: Reverse invocation of notifiers during CPU hotplug References: <50101733.4030205@linux.vnet.ibm.com> <50102424.5010301@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12072611-8878-0000-0000-000003647697 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/26/2012 04:32 PM, Thomas Gleixner wrote: > On Wed, 25 Jul 2012, Srivatsa S. Bhat wrote: >> On 07/25/2012 10:00 PM, Thomas Gleixner wrote: >>> While I thought about having a full dependency tracking system, I'm >>> quite convinced by now, that hotplug is a rather linear sequence which >>> does not provide much room for paralell setup/teardown. >>> >> >> Pretty much, when considering hotplug of a single CPU. >> >> (But when considering booting, Arjan had proposed (while discussing >> about his asynchronous booting patch) that it would be good to split >> up physical vs logical parts of the booting/hotplug, so that the >> physical part can happen in parallel with other CPUs, while the >> logical online can be done serially, much later. Anyway, this is >> slightly off-topic here, since we are mainly talking about hotplug >> of a single cpu here. I just thought of putting a word about that >> here, since we are discussing hotplug redesign anyways..) > > Well, the nice thing about having a proper state machine is that you > can tell the code to advance the BP only to the "kick the other cpu" > step, which is before the first sync point, so you can leave the state > there and continue with "bring it fully online" later. > > So that feature comes basically for free. :) > Ah! Nice :-) Regards, Srivatsa S. Bhat