From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932189AbWBQDQR (ORCPT ); Thu, 16 Feb 2006 22:16:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932257AbWBQDQR (ORCPT ); Thu, 16 Feb 2006 22:16:17 -0500 Received: from omta02ps.mx.bigpond.com ([144.140.83.154]:11367 "EHLO omta02ps.mx.bigpond.com") by vger.kernel.org with ESMTP id S932189AbWBQDQQ (ORCPT ); Thu, 16 Feb 2006 22:16:16 -0500 Message-ID: <43F53FFD.7020209@bigpond.net.au> Date: Fri, 17 Feb 2006 14:16:13 +1100 From: Peter Williams User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Siddha, Suresh B" CC: Andrew Morton , Linux Kernel Mailing List , npiggin@suse.de, Ingo Molnar , Steven Rostedt , Linus Torvalds , Con Kolivas Subject: Re: [PATCH] Fix smpnice high priority task hopping problem References: <43F3C9C6.5080606@bigpond.net.au> <20060216171357.A27025@unix-os.sc.intel.com> <43F53553.50904@bigpond.net.au> <43F53A42.2090909@bigpond.net.au> <20060216185837.C27025@unix-os.sc.intel.com> In-Reply-To: <20060216185837.C27025@unix-os.sc.intel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH PLAIN at omta02ps.mx.bigpond.com from [147.10.133.38] using ID pwil3058@bigpond.net.au at Fri, 17 Feb 2006 03:16:14 +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Siddha, Suresh B wrote: > On Fri, Feb 17, 2006 at 01:51:46PM +1100, Peter Williams wrote: > >>Peter Williams wrote: >> >>>There's a rational argument (IMHO) that this patch should be applied >>>even in the absence of the smpnice patches as it prevents >>>active_load_balance() doing unnecessary work. If this isn't good for >>>hypo threading then hypo threading is a special case and needs to handle >>>it as such. >> >>OK. The good news is that (my testing shows that) the "sched: fix >>smpnice abnormal nice anomalies" fixes the imbalance problem and the >>consequent CPU hopping. > > > Thats because find_busiest_group() is no longer showing the imbalance :) > Anyhow if I get time I will review this patch before I start my vacation. > Otherwise I assume Nick and Ingo will review this closely.. > > >>BUT I still think that this patch (modified if necessary to handle any >>HT special cases) should be applied. On a normal system, it will (as >>I've already said) stop active_load_balance() from doing a lot of >>unnecessary work INCLUDING holding the run queue locks for TWO run >>queues for no good reason. > > > Please see my earlier response to this.. I saw nothing there to convince me that this patch isn't worthwhile. Perhaps a better explanation would help me? Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce