From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765536AbXGYUzY (ORCPT ); Wed, 25 Jul 2007 16:55:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757841AbXGYUzN (ORCPT ); Wed, 25 Jul 2007 16:55:13 -0400 Received: from mx1.redhat.com ([66.187.233.31]:42154 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757034AbXGYUzM (ORCPT ); Wed, 25 Jul 2007 16:55:12 -0400 Message-ID: <46A7B8A9.4040400@redhat.com> Date: Wed, 25 Jul 2007 16:55:05 -0400 From: Chris Snook User-Agent: Thunderbird 2.0.0.0 (X11/20070419) MIME-Version: 1.0 To: Chris Friesen CC: Ingo Molnar , Tong Li , linux-kernel@vger.kernel.org Subject: Re: [RFC] scheduler: improve SMP fairness in CFS References: <20070725110159.GA15076@elte.hu> <20070725120358.GA30755@elte.hu> <20070725192442.GC4463@elte.hu> <46A7B4DE.4030301@nortel.com> In-Reply-To: <46A7B4DE.4030301@nortel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Chris Friesen wrote: > Ingo Molnar wrote: > >> the 3s is the problem: change that to 60s! We no way want to >> over-migrate for SMP fairness, the change i did gives us reasonable >> long-term SMP fairness without the need for high-rate rebalancing. > > Actually, I do have requirements from our engineering guys for > short-term fairness. They'd actually like decent fairness over even > shorter intervals...1 second would be nice, 2 is acceptable. > > They are willing to trade off random peak performance for predictability. > > Chris > The sysctls for CFS have nanosecond resolution. They default to millisecond-order values, but you can set them much lower. See sched_fair.c for the knobs and their explanations. -- Chris