From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266955AbUBMMgI (ORCPT ); Fri, 13 Feb 2004 07:36:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266959AbUBMMgI (ORCPT ); Fri, 13 Feb 2004 07:36:08 -0500 Received: from columba.eur.3com.com ([161.71.171.238]:53965 "EHLO columba.eur.3com.com") by vger.kernel.org with ESMTP id S266955AbUBMMgF (ORCPT ); Fri, 13 Feb 2004 07:36:05 -0500 Message-ID: <402CC4AE.7050904@jburgess.uklinux.net> Date: Fri, 13 Feb 2004 12:35:58 +0000 From: Jon Burgess User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6) Gecko/20040113 X-Accept-Language: en-gb, en-us, en MIME-Version: 1.0 To: Andrew Morton CC: Jon Burgess , linux-kernel@vger.kernel.org Subject: Re: ext2/3 performance regression in 2.6 vs 2.4 for small interleaved writes References: <402A7CA0.9040409@jburgess.uklinux.net> <20040212015626.48631555.akpm@osdl.org> In-Reply-To: <20040212015626.48631555.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: >What filesytem was that with? > > I re-ran the tests again last night and founfd that I had made one mistake in my description. The really poor results occured with the *ext3* filesystem, not ext2. "mount" was telling me that the contents of /etc/fstab which was ext2 - but the kernel actually had it mounted it as ext3. I think I might be able to give a little insight to the "0.34MB/s" and "0.48MB/s" numbers. I think these numbers closely match the theoretical performance rate when a single 4kB write occurs per disk rotation. 4kB * 5400RPM / 60 seconds = 360 kB/s 4kB * 7200RPM / 60 seconds = 480 kB/s Perhaps the drives that I am running the test on do not have write-caching enabled. By the time the first 4kB write has completed the drive may need to wait a complete rotation before it can do the next write. I don't think it quite explains the difference between ext2 and ext3. Any ideas? Below are the resuls of ext2/ext3 tests on a new Seagate 80Gb SATA, 8MB Cache, model ST380023AS. The ext3 results are a lot better, perhaps this drive has write caching enabled. Num streams |1 1 |2 2 |4 4 Filesystem |Write Read |Write Read |Write Read ------------------------------|--------------|-------------- Ext2 |40.17 43.07 |10.88 21.49 |10.13 11.41 ext3-journal |16.06 42.24 | 7.56 16.28 | 7.17 11.25 ext3-ordered |37.31 43.12 | 4.64 15.33 | 5.25 11.28 ext3-writeback |37.33 42.93 | 4.00 14.88 | 2.97 11.26 Jon