From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265663AbUBFW7i (ORCPT ); Fri, 6 Feb 2004 17:59:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265673AbUBFW7h (ORCPT ); Fri, 6 Feb 2004 17:59:37 -0500 Received: from mail-10.iinet.net.au ([203.59.3.42]:2769 "HELO mail.iinet.net.au") by vger.kernel.org with SMTP id S265663AbUBFW7a (ORCPT ); Fri, 6 Feb 2004 17:59:30 -0500 Message-ID: <40241AFC.9030603@cyberone.com.au> Date: Sat, 07 Feb 2004 09:53:48 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040122 Debian/1.6-1 X-Accept-Language: en MIME-Version: 1.0 To: "Martin J. Bligh" CC: Rick Lindsley , Anton Blanchard , akpm@osdl.org, linux-kernel@vger.kernel.org, dvhltc@us.ibm.com Subject: Re: [PATCH] Load balancing problem in 2.6.2-mm1 References: <200402061815.i16IFhY07073@owlet.beaverton.ibm.com> <207100000.1076092771@flay> <40240F07.9060105@cyberone.com.au> <225230000.1076107348@flay> In-Reply-To: <225230000.1076107348@flay> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Martin J. Bligh wrote: >>>It's the classic fairness vs throughput thing we've argued about before. >>>Most workloads don't have that static a number of processes, but it >>>probably does need to do it if the imbalance is persistent ... but much >>>more reluctantly than normal balancing. See the patch I sent out a bit >>>earlier to test it - that may be *too* extreme in the other direction, >>>but it should confirm what's going on, at least. >>> >>Yep. I've argued for fairness here, and that is presently what >>we get. Between nodes the threshold should probably be higher >>though. >> > >OK, but do you agree that the rate we rebalance things like 2 vs 1 should >be slower than the rate we rebalance 3 vs 1 ? Fairness is only relevant >over a long term imbalance anyway, so there should be a big damper on >"fairness only" rebalances. > > Well presently it happens at the same rate. This isn't bad though, because you just use the more conservative rate. Its probably not worth distinguishing the two cases. If a CPU becomes idle, it will attempt to balance immediately. >Moreover, as Rick pointed out, it's particularly futile over idle cpus ;-) > > I don't follow...