From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753342Ab0CWN1W (ORCPT ); Tue, 23 Mar 2010 09:27:22 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:51629 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351Ab0CWN1V (ORCPT ); Tue, 23 Mar 2010 09:27:21 -0400 Date: Tue, 23 Mar 2010 14:27:19 +0100 From: Jens Axboe To: Pawel S Cc: linux-kernel@vger.kernel.org, Ben Gamari , tytso , Nick Piggin , Ingo Molnar , Andrew Morton Subject: Re: Poor interactive performance with I/O loads with fsync()ing Message-ID: <20100323132719.GY5768@kernel.dk> References: <8c4cf08c1003230428t274b8ca8y13d67d65b8830dd7@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c4cf08c1003230428t274b8ca8y13d67d65b8830dd7@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 23 2010, Pawel S wrote: > Hello > > I am experiencing very similar issue. My system is a regular desktop > PC and it suffers from very high I/O latencies (sometimes desktop > "hangs" for eight seconds or more) when copying large files. I tried > kernels up to 2.6.34-rc2, but without luck. This issue was raised at > Phoronix forums and Arjan (from Intel) noticed it can be VM related: > > http://www.phoronix.com/forums/showpost.php?p=114975&postcount=51 > > Here is my perf timechart where you can notice I/O "steals" CPU from > the other tasks: > > http://hotfile.com/dl/30596827/ebe566b/output.svg.gz.html It's also been my sneaking suspicion that swap is involved. I had lots of RAM in anything I use, even the laptop and workstation. I'll try and run some tests with lower memory and force it into swap, I've seen nasty hangs that way. -- Jens Axboe