Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761269AbXETBl6 (ORCPT ); Sat, 19 May 2007 21:41:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756757AbXETBlu (ORCPT ); Sat, 19 May 2007 21:41:50 -0400 Received: from omta04ps.mx.bigpond.com ([144.140.83.156]:32842 "EHLO omta04ps.mx.bigpond.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756622AbXETBlu (ORCPT ); Sat, 19 May 2007 21:41:50 -0400 Message-ID: <464FA753.7040206@bigpond.net.au> Date: Sun, 20 May 2007 11:41:39 +1000 From: Peter Williams User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Dmitry Adamushko CC: Ingo Molnar , Linux Kernel Subject: Re: [patch] CFS scheduler, -v12 References: <20070513153853.GA19846@elte.hu> <464A6698.3080400@bigpond.net.au> <20070516063625.GA9058@elte.hu> <464CE8FD.4070205@bigpond.net.au> <20070518071325.GB28702@elte.hu> <464DA61A.4040406@bigpond.net.au> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH PLAIN at oaamta08ps.mx.bigpond.com from [144.131.192.218] using ID pwil3058@bigpond.net.au at Sun, 20 May 2007 01:41:44 +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2078 Lines: 43 Dmitry Adamushko wrote: > On 18/05/07, Peter Williams wrote: >> [...] >> One thing that might work is to jitter the load balancing interval a >> bit. The reason I say this is that one of the characteristics of top >> and gkrellm is that they run at a more or less constant interval (and, >> in this case, X would also be following this pattern as it's doing >> screen updates for top and gkrellm) and this means that it's possible >> for the load balancing interval to synchronize with their intervals >> which in turn causes the observed problem. A jittered load balancing >> interval should break the synchronization. This would certainly be >> simpler than trying to change the move_task() logic for selecting which >> tasks to move. > > Just an(quick) another idea. Say, the load balancer would consider not > only p->load_weight but also something like Tw(task) = > (time_spent_on_runqueue / total_task's_runtime) * some_scale_constant > as an additional "load" component (OTOH, when a task starts, it takes > some time for this parameter to become meaningful). I guess, it could > address the scenarios your have described (but maybe break some others > as well :) ... > Any hints on why it's stupid? Well that is the kind of thing I was hoping to avoid for the reasons of complexity. I think that the actual implementation would be more complex than it sounds and possibly require multiple runs down the list of moveable tasks which would be bad for overhead. Basically, I don't think that the problem is serious enough to warrant a complex solution. But I may be wrong about how complex the implementation would be. Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/