From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267626AbUGWLDQ (ORCPT ); Fri, 23 Jul 2004 07:03:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267627AbUGWLDQ (ORCPT ); Fri, 23 Jul 2004 07:03:16 -0400 Received: from mx1.elte.hu ([157.181.1.137]:53169 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S267626AbUGWLDO (ORCPT ); Fri, 23 Jul 2004 07:03:14 -0400 Date: Fri, 23 Jul 2004 13:04:30 +0200 From: Ingo Molnar To: Paolo Ciarrocchi Cc: linux-kernel@vger.kernel.org, Rudo Thomas , Matt Heler Subject: Re: [patch] voluntary-preempt-2.6.8-rc2-I3 Message-ID: <20040723110430.GA3787@elte.hu> References: <20040722100657.GA14909@elte.hu> <20040722160055.GA4837@ss1000.ms.mff.cuni.cz> <20040722161941.GA23972@elte.hu> <20040722172428.GA5632@ss1000.ms.mff.cuni.cz> <20040722175457.GA5855@ss1000.ms.mff.cuni.cz> <20040722180142.GC30059@elte.hu> <20040722180821.GA377@elte.hu> <20040722181426.GA892@elte.hu> <20040723104246.GA2752@elte.hu> <4d8e3fd30407230358141e0e58@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4d8e3fd30407230358141e0e58@mail.gmail.com> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Paolo Ciarrocchi wrote: > > i've uploaded the -I3 voluntary-preempt patch: > > > > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8-rc2-I3 > > > > it mainly fixes an ext3 livelock that could result in long delays during > > heavy commit traffic. > > Hello Ingo, do you have any measurement of the improvement available ? it's a bug in the patch, not really a latency fix. When this (rare) condition under heavy write traffic occurs then kjournald would loop for many seconds (or tens of seconds) in __journal_clean_checkpoint_list(), effectively hanging the system. The system is still preemptible but the user cannot do much with it. Note that this condition is not present in the vanilla kernel, it got introduced by earlier versions of voluntary-preempt. Ingo