From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754892AbZBWLZl (ORCPT ); Mon, 23 Feb 2009 06:25:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753337AbZBWLZa (ORCPT ); Mon, 23 Feb 2009 06:25:30 -0500 Received: from e28smtp09.in.ibm.com ([59.145.155.9]:36223 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754750AbZBWLZ3 (ORCPT ); Mon, 23 Feb 2009 06:25:29 -0500 Date: Mon, 23 Feb 2009 16:55:17 +0530 From: Balbir Singh To: Ingo Molnar Cc: Vaidyanathan Srinivasan , 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: <20090223112517.GD10226@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <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> <20090223110725.GB17312@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090223110725.GB17312@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar [2009-02-23 12:07:25]: > > * 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. > OK, lets head that way for now. I've highlighted my concerns in a different email. Experimentation will definitely show us if they are justified or not. -- Balbir