From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968793AbXG3Vu0 (ORCPT ); Mon, 30 Jul 2007 17:50:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S967979AbXG3VuL (ORCPT ); Mon, 30 Jul 2007 17:50:11 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:40753 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967923AbXG3VuJ (ORCPT ); Mon, 30 Jul 2007 17:50:09 -0400 Subject: Re: [PATCH RT] Fix RT balancing tasks pulling From: Josh Triplett To: =?ISO-8859-1?Q?S=E9bastien_Dugu=E9?= Cc: Linux RT Users , linux-kernel , Ingo Molnar , Thomas Gleixner , Jean Pierre Dion , Darren Hart , john stultz In-Reply-To: <20070724154202.224f12e8@frecb000686.frec.bull.fr> References: <20070724154202.224f12e8@frecb000686.frec.bull.fr> Content-Type: text/plain; charset=utf-8 Date: Mon, 30 Jul 2007 14:50:34 -0700 Message-Id: <1185832234.3334.35.camel@josh-work.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.6.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-07-24 at 15:42 +0200, Sébastien Dugué wrote: > this one-liner fixes a bug in balance_rt_tasks() which sometimes manifests by > having a lower prio task being scheduled while a higher prio task is sitting > waiting on another runqueue. > > This is pretty hard to reproduce on low cpu count machines, for example, I > had to have sched_football run in a loop for ~38h before it failed on a dual HT > Xeon box. Very impressive find, and this does seem to improve things in some cases. However, with 2.6.22.1-rt8, which includes this patch, I still managed to get some failures after a few hours on an 8-way (quad dual-core) box. Preliminary results so far: 420 Final ball position: 0 2 Final ball position: 1 - Josh Triplett