From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757722AbZBTQIT (ORCPT ); Fri, 20 Feb 2009 11:08:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752367AbZBTQIG (ORCPT ); Fri, 20 Feb 2009 11:08:06 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:56178 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751927AbZBTQIF (ORCPT ); Fri, 20 Feb 2009 11:08:05 -0500 Date: Fri, 20 Feb 2009 17:07:37 +0100 From: Ingo Molnar To: Vaidyanathan Srinivasan Cc: 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, arjan@infradead.org, arun@linux.vnet.ibm.com, Vaidyanathan Srinivasan , Suresh Siddha Subject: Re: [RFC PATCH 0/4] timers: framework for migration between CPU Message-ID: <20090220160737.GC11294@elte.hu> References: <20090220125516.GB10232@linux.vnet.ibm.com> <20090220132145.GF26418@elte.hu> <20090220141415.GA27381@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090220141415.GA27381@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: > > 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. Ingo