From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 26 Jul 2002 14:55:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 26 Jul 2002 14:55:23 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:15122 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Fri, 26 Jul 2002 14:55:23 -0400 Message-ID: <3D419B59.E99F74DC@zip.com.au> Date: Fri, 26 Jul 2002 11:56:25 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre8 i686) X-Accept-Language: en MIME-Version: 1.0 To: Steven Cole CC: "Stephen C. Tweedie" , linux-kernel@vger.kernel.org, Steven Cole Subject: Re: 2.5.28, dbench results with ext3 significantly lower than with ext2. References: <1027701923.3148.10.camel@spc9.esa.lanl.gov> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Steven Cole wrote: > > I found that dbench gives significantly lower numbers when > the partition on which it is run is mounted as ext3. > ext2 will force writeback when 40% of ZONE_NORMAL is dirty. That's normally >300 megabytes. ext3 will force writeback when 75% of the journal space is consumed by metadata. That's normally 24 megabytes. dbench generates a storm of metadata and data and then deletes it all. It consumes the journal space almost immediately and forces ext3 to do a lot of writeback. ext2 benefits because most of the metadata and data are deleted before they ever touch disk. If your application generates unusually high volumes of metadata and data and then immediately deletes it, ext3 may not be an appropriate filesystem. -