From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755221Ab0H0Sid (ORCPT ); Fri, 27 Aug 2010 14:38:33 -0400 Received: from mail.openrapids.net ([64.15.138.104]:60529 "EHLO blackscsi.openrapids.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752363Ab0H0Sib (ORCPT ); Fri, 27 Aug 2010 14:38:31 -0400 Date: Fri, 27 Aug 2010 14:38:30 -0400 From: Mathieu Desnoyers To: Mike Galbraith Cc: Peter Zijlstra , LKML , Linus Torvalds , Andrew Morton , Ingo Molnar , Steven Rostedt , Thomas Gleixner , Tony Lindgren Subject: Re: [RFC PATCH 00/11] sched: CFS low-latency features Message-ID: <20100827183830.GD22679@Krystal> References: <20100826180908.648103531@efficios.com> <1282849045.1975.1587.camel@laptop> <20100826234910.GB4194@Krystal> <1282894960.1975.1666.camel@laptop> <1282897192.7185.28.camel@marge.simson.net> <20100827154334.GE14926@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100827154334.GE14926@Krystal> X-Editor: vi X-Info: http://www.efficios.com X-Operating-System: Linux/2.6.26-2-686 (i686) X-Uptime: 14:37:55 up 216 days, 21:14, 4 users, load average: 0.05, 0.05, 0.00 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 * Mathieu Desnoyers (mathieu.desnoyers@efficios.com) wrote: > * Mike Galbraith (efault@gmx.de) wrote: > > On Fri, 2010-08-27 at 09:42 +0200, Peter Zijlstra wrote: > > > On Thu, 2010-08-26 at 19:49 -0400, Mathieu Desnoyers wrote: > > > > AFAIK, I don't think we would end up starving the system in any possible way. > > > > > > Correct, it does maintain fairness. > > > > > > > So far I cannot see a situation where selecting the next buddy would _not_ make > > > > sense in any kind of input-driven wakeups (interactive, timer, disk, network, > > > > etc). But maybe it's just a lack of imagination on my part. > > > > > > The risk is that you end up with always using next-buddy, and we tried > > > that a while back and that didn't work well for some, Mike might > > > remember. > > > > I turned it off because it was ripping spread apart badly, and last > > buddy did a better job of improving scalability without it. > > Maybe with the dyn min_vruntime feature proposed in this patchset we should > reconsider this. Spread being ripped apart is exactly what it addresses. I'm curious: which workload was showing this kind of problem exactly ? Thanks, Mathieu -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com