From: Michael Tokarev Subject: Re: EXT4 is ~2X as slow as XFS (593MB/s vs 304MB/s) for writes? Date: Mon, 01 Mar 2010 17:48:16 +0300 Message-ID: <4B8BD3B0.3020502@msgid.tls.msk.ru> References: <4B886CA1.9050906@redhat.com> <4B887160.2090606@redhat.com> <4B887548.50508@redhat.com> <20100228054240.GE14646@thunk.org> <832C6227-BF34-43C2-8768-1308C00AB17F@sun.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , tytso@mit.edu, Eric Sandeen , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Alan Piszcz To: Justin Piszcz Return-path: Received: from isrv.corpit.ru ([81.13.33.159]:46256 "EHLO isrv.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751056Ab0CAOsS (ORCPT ); Mon, 1 Mar 2010 09:48:18 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Justin Piszcz wrote: > > On Mon, 1 Mar 2010, Andreas Dilger wrote: > >> On 2010-02-28, at 07:55, Justin Piszcz wrote: >>> === CREATE RAID-0 WITH 11 DISKS >> >> Have you tried testing with "nice" numbers of disks in your RAID set >> (e.g. 8 disks for RAID-0, 9 for RAID-5, 10 for RAID-6)? The mballoc >> code is really much better tuned for power-of-two sized allocations. > > Hi, > > Yes, the second system (RAID-5) has 8 disks and it shows the same > performance problems with ext4 and not XFS (as shown from previous > e-mail), where XFS usually got 500-600MiB/s for writes. > > http://groups.google.com/group/linux.kernel/browse_thread/thread/e7b189bcaa2c1cb4/ad6c2a54b678cf5f?show_docid=ad6c2a54b678cf5f&pli=1 > > > For the RAID-5 (from earlier testing): <- This one has 8 disks. Note that for RAID-5, the "nice" number of disks is 9 as Andreas said, not 8 as in your example. /mjt