From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967741AbXEIDaT (ORCPT ); Tue, 8 May 2007 23:30:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S967498AbXEIDaF (ORCPT ); Tue, 8 May 2007 23:30:05 -0400 Received: from mail.gmx.net ([213.165.64.20]:47174 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754293AbXEIDaB (ORCPT ); Tue, 8 May 2007 23:30:01 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX18pOThOwvIpGdOIaEwPx1aS94OuaOkvpPEOgX87dC z4I/MZnRfkRbe+ Subject: Re: multi-second freezes with current GIT? From: Mike Galbraith To: David Miller Cc: linux-kernel@vger.kernel.org In-Reply-To: <20070508.184458.21594839.davem@davemloft.net> References: <20070508.184458.21594839.davem@davemloft.net> Content-Type: text/plain Date: Wed, 09 May 2007 05:29:20 +0200 Message-Id: <1178681360.7487.59.camel@Homer.simpson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-05-08 at 18:44 -0700, David Miller wrote: > I've been noticing this off and on for the past week or so. > > The system seems to jam up for several seconds, anything that would > need to read from disk just sits there during this time. I think it's > correlated with generating a lot of dirty write data. > > My mouse moves around in X etc. so it really is only processes that > need to read from disk that get stuck. > > Perhaps it's a side effect of those dirty ratio changes Linus made to > start off the 2.6.22 merge cycle? Uhoh, that seems highly likely. I think those changes may have been triggered by my repeatable and truly horrible system stalls when writing to an ext3 data=ordered nearly full filesystem. Anything that does fdatasync() and/or fsync() can cause very bad experiences indeed. KDE's little menu/program launcher doohickey does fdatasync() for some odd reason, which has utterly killed my entire GUI for up to and including 20 minutes at a whack. Switching to data=writeback cured those horrors. Lowering the dirty ratio reduced the agony of data=ordered tremendously, but didn't make it even remotely acceptable. -Mike