From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Thu, 28 Dec 2006 01:51:28 -0800 (PST) Received: from deflector.emaze.net (deflector.emaze.net [213.178.220.4]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id kBS9pJqw024375 for ; Thu, 28 Dec 2006 01:51:21 -0800 Message-ID: <459394EA.3000304@emaze.net> Date: Thu, 28 Dec 2006 10:56:58 +0100 From: Francesco Degrassi MIME-Version: 1.0 Subject: Re: Possible performance problem introduced between kernel 2.6.15 and 2.6.17 on xfs code References: <458D4845.2010803@emaze.net> <458D4EEB.3060501@sandeen.net> <458DCB8D.3040804@emaze.net> <4592942C.5000306@sandeen.net> <4592B581.7080806@emaze.net> <20061227180542.GA6888@teal.hq.k1024.org> In-Reply-To: <20061227180542.GA6888@teal.hq.k1024.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: iusty@k1024.org Cc: Eric Sandeen , linux-xfs@oss.sgi.com Hi Iustin, i tried and it and indeed the performance problem does not manifest if i mount the xfs filesystem with the -o nobarrier option. Seems like we are a little bit closer to the real problem now. The code in gnomevfs-copy calls fadvice POSIX_FADV_DONTNEED (in gnome_vfs_forget_cache) and disabling this behaviour gets back normal performance, so it has something to do with that. Thanks for your help Francesco Iustin Pop wrote: > On Wed, Dec 27, 2006 at 07:03:45PM +0100, Francesco Degrassi wrote: >> I tried ext2, ext3, jfs, reiser3, vfat and the problem does not show up. >> Anyway i discovered that if i create a regular file in an XFS partition, >> create an XFS filesystem on it as if it was a regular block device, and >> mount it with the loop device, the problem does NOT manifest. >> So it seems to affect XFS filesystems on regular block devices only ? >> I'm confused. > > This is probably not related, but I remember that barriers were added > sometime between 2.6.15 and 2.6.17 and probably barriers are not enabled > on a loop filesystem. Maybe the gnome vfs thing does some sync which > force flushes or such. I'm no expert, just guessing. > > Just to invalidate this (probably wrong) guess, could you try to mount > /tmp with "-o nobarrier" and re-test? > > Iustin, who wishes md raid1 would support barriers.