From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265215AbUGQQpA (ORCPT ); Sat, 17 Jul 2004 12:45:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266182AbUGQQpA (ORCPT ); Sat, 17 Jul 2004 12:45:00 -0400 Received: from mtvcafw.SGI.COM ([192.48.171.6]:29390 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S265215AbUGQQo7 (ORCPT ); Sat, 17 Jul 2004 12:44:59 -0400 From: Jesse Barnes To: Nick Piggin Subject: Re: [PATCH] reduce inter-node balancing frequency Date: Sat, 17 Jul 2004 12:44:11 -0400 User-Agent: KMail/1.6.2 Cc: "Martin J. Bligh" , linux-kernel , John Hawkes References: <200407151829.20069.jbarnes@engr.sgi.com> <200407161045.38983.jbarnes@engr.sgi.com> <40F8965E.6070809@yahoo.com.au> In-Reply-To: <40F8965E.6070809@yahoo.com.au> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200407171244.11008.jbarnes@engr.sgi.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday, July 16, 2004 11:00 pm, Nick Piggin wrote: > Out of interest, what sort of performance problems are you seeing with > this high rate of global balancing? I have a couple of patches to cut down > runqueue locking to almost zero in interrupt paths, although I imagine the > main problem you are having is pulling a cacheline off every remote CPU > when calculating runqueue loads? John might remember the details, I didn't get a backtrace this time. When we boot with the default values on a 512p system, it livelocks shortly after init starts. I *think* what's happening is that a the global rebalance value is shorter than the time it takes to do the global rebalance, due to cacheline contention. Jesse