From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755968AbZBTVyA (ORCPT ); Fri, 20 Feb 2009 16:54:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754289AbZBTVxv (ORCPT ); Fri, 20 Feb 2009 16:53:51 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:48943 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753749AbZBTVxu (ORCPT ); Fri, 20 Feb 2009 16:53:50 -0500 Date: Fri, 20 Feb 2009 22:53:18 +0100 From: Ingo Molnar To: Arjan van de Ven Cc: Vaidyanathan Srinivasan , 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: <20090220215318.GA30665@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090220115745.43d202d6@infradead.org> 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 * Arjan van de Ven wrote: > On Fri, 20 Feb 2009 17:07:37 +0100 > Ingo Molnar wrote: > > > > > * Vaidyanathan Srinivasan wrote: > > > > > > I'd also suggest to not do that rather ugly > > > > enable_timer_migration per-cpu variable, but simply reuse > > > > the existing nohz.load_balancer as a target CPU. > > > > > > This is a good idea to automatically bias the timers. But > > > this nohz.load_balancer is a very fast moving target and we > > > will need some heuristics to estimate overall system idleness > > > before moving the timers. > > > > > > I would agree that the power saving load balancer has a good > > > view of the system and can potentially guide the timer biasing > > > framework. > > > > Yeah, it's a fast moving target, but it already concentrates > > the load somewhat. > > > > I wonder if the real answer for this isn't to have timers be > considered schedulable-entities and have the regular scheduler > decide where they actually run. hm, not sure - it's a bit heavy for that. Ingo