From: Eric Sandeen Subject: More testing: 4x parallel 2G writes, sequential reads Date: Wed, 07 Nov 2007 16:42:59 -0600 Message-ID: <47323F73.5080708@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: ext4 development Return-path: Received: from mx1.redhat.com ([66.187.233.31]:39440 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752151AbXKGWnD (ORCPT ); Wed, 7 Nov 2007 17:43:03 -0500 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.1) with ESMTP id lA7Mh1V0001604 for ; Wed, 7 Nov 2007 17:43:01 -0500 Received: from lacrosse.corp.redhat.com (lacrosse.corp.redhat.com [172.16.52.154]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id lA7Mh1Yr017595 for ; Wed, 7 Nov 2007 17:43:01 -0500 Received: from [10.15.80.10] (neon.msp.redhat.com [10.15.80.10]) by lacrosse.corp.redhat.com (8.12.11.20060308/8.11.6) with ESMTP id lA7Mgxk2004134 for ; Wed, 7 Nov 2007 17:43:00 -0500 Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org I tried ext4 vs. xfs doing 4 parallel 2G IO writes in 1M units to 4 different subdirectories of the root of the filesystem: http://people.redhat.com/esandeen/seekwatcher/ext4_4_threads.png http://people.redhat.com/esandeen/seekwatcher/xfs_4_threads.png http://people.redhat.com/esandeen/seekwatcher/ext4_xfs_4_threads.png and then read them back sequentially: http://people.redhat.com/esandeen/seekwatcher/ext4_4_threads_read.png http://people.redhat.com/esandeen/seekwatcher/xfs_4_threads_read.png http://people.redhat.com/esandeen/seekwatcher/ext4_xfs_4_read_threads.png At the end of the write, ext4 had on the order of 400 extents/file, xfs had on the order of 30 extents/file. It's clear especially from the read graph that ext4 is interleaving the 4 files, in about 5M chunks on average. Throughput seems comparable between ext4 & xfs nonetheless. Again this was on a decent HW raid so seek penalties are probably not too bad. -Eric