From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265708AbUBFWnY (ORCPT ); Fri, 6 Feb 2004 17:43:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265649AbUBFWnY (ORCPT ); Fri, 6 Feb 2004 17:43:24 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.106]:40422 "EHLO e6.ny.us.ibm.com") by vger.kernel.org with ESMTP id S266890AbUBFWmu (ORCPT ); Fri, 6 Feb 2004 17:42:50 -0500 Date: Fri, 06 Feb 2004 14:42:28 -0800 From: "Martin J. Bligh" To: Nick Piggin 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 Message-ID: <225230000.1076107348@flay> In-Reply-To: <40240F07.9060105@cyberone.com.au> References: <200402061815.i16IFhY07073@owlet.beaverton.ibm.com> <207100000.1076092771@flay> <40240F07.9060105@cyberone.com.au> X-Mailer: Mulberry/2.1.2 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> 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. Moreover, as Rick pointed out, it's particularly futile over idle cpus ;-) m.