From mboxrd@z Thu Jan 1 00:00:00 1970 From: Szabolcs Szakacsits Subject: Re: XFS vs Elevators (was Re: [PATCH RFC] nilfs2: continuous snapshotting file system) Date: Fri, 22 Aug 2008 15:44:29 +0300 (MET DST) Message-ID: References: <200808201613.AA00212@capsicum.lab.ntt.co.jp> <20080820143916.1a7eddab.akpm@linux-foundation.org> <20080821021259.GA5706@disturbed> <20080821051508.GB5706@disturbed> <20080821060418.GC5706@disturbed> <20080821082532.GE5706@disturbed> <20080822022459.GL5706@disturbed> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com To: Dave Chinner Return-path: Received: from emh06.mail.saunalahti.fi ([62.142.5.116]:43179 "EHLO emh06.mail.saunalahti.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755036AbYHVMmA (ORCPT ); Fri, 22 Aug 2008 08:42:00 -0400 In-Reply-To: <20080822022459.GL5706@disturbed> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, 22 Aug 2008, Dave Chinner wrote: > On Thu, Aug 21, 2008 at 08:33:50PM +0300, Szabolcs Szakacsits wrote: > > > The 'nobarrier' mount option made a big improvement: > > INteresting. Barriers make only a little difference on my laptop; > 10-20% slower. But yes, barriers will have this effect on XFS. > > If you've got NCQ, then you'd do better to turn off write caching > on the drive, turn off barriers and use NCQ to give you back the > performance that the write cache used to. That is, of course, > assuming the NCQ implementation doesn't suck.... Write cache off, nobarrier and AHCI NCQ lowered the XFS result: MB/s Runtime (s) ----- ----------- btrfs unstable 17.09 572 ext3 13.24 877 btrfs 0.16 12.33 793 ntfs-3g unstable 11.52 673 nilfs2 2nd+ runs 11.29 674 reiserfs 8.38 966 xfs nobarrier 7.89 949 nilfs2 1st run 4.95 3800 xfs nobarrier, ncq, wc off 3.81 1973 xfs 1.88 3901 Szaka -- NTFS-3G: http://ntfs-3g.org