From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754688AbZBWLIA (ORCPT ); Mon, 23 Feb 2009 06:08:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752923AbZBWLHv (ORCPT ); Mon, 23 Feb 2009 06:07:51 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:58154 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752858AbZBWLHv (ORCPT ); Mon, 23 Feb 2009 06:07:51 -0500 Date: Mon, 23 Feb 2009 12:07:25 +0100 From: Ingo Molnar To: Vaidyanathan Srinivasan Cc: Balbir Singh , Arjan van de Ven , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, a.p.zijlstra@chello.nl, ego@in.ibm.com, tglx@linutronix.de, andi@firstfloor.org, venkatesh.pallipadi@intel.com, vatsa@linux.vnet.ibm.com, arun@linux.vnet.ibm.com, Suresh Siddha Subject: Re: [RFC PATCH 0/4] timers: framework for migration between CPU Message-ID: <20090223110725.GB17312@elte.hu> References: <20090220125516.GB10232@linux.vnet.ibm.com> <20090220132145.GF26418@elte.hu> <20090220141415.GA27381@dirshya.in.ibm.com> <20090220160737.GC11294@elte.hu> <20090220115745.43d202d6@infradead.org> <20090220215318.GA30665@elte.hu> <20090223075521.GA3725@balbir.in.ibm.com> <20090223091158.GJ9582@elte.hu> <20090223094850.GA10226@balbir.in.ibm.com> <20090223103814.GB8817@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090223103814.GB8817@dirshya.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Vaidyanathan Srinivasan wrote: > My understanding is that we will certainly have a sysfs > tunable to 'enable' timer migration or consolidation, similar > to the sched_mc=2 policy, but the actual set of CPUs to > evacuate and the correct set of target CPUs to consolidate > should come from the scheduler and not necessarily from the > user space. Yes. > The scheduler should be able to figure out the following > parameters: > > * Identify set of idle CPUs (CPU package) from which timers > can be removed > * Identify a semi-idle or idle CPU package to which the timers > can be moved > * Decide when to start moving timers as the system has large > number of idle CPUs > * Decide when to stop migrating as system becomes less idle > and utilisation increases > > Guiding all of the above decisions from user space may not be > fast enough. Exactly. Ingo