Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 26 Jul 2002 14:52:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 26 Jul 2002 14:52:37 -0400 Received: from pc-62-30-72-138-ed.blueyonder.co.uk ([62.30.72.138]:55681 "EHLO sisko.scot.redhat.com") by vger.kernel.org with ESMTP id ; Fri, 26 Jul 2002 14:52:37 -0400 Date: Fri, 26 Jul 2002 19:55:28 +0100 From: "Stephen C. Tweedie" To: Steven Cole Cc: "Stephen C. Tweedie" , Andrew Morton , linux-kernel@vger.kernel.org, Steven Cole Subject: Re: 2.5.28, dbench results with ext3 significantly lower than with ext2. Message-ID: <20020726195528.B2299@redhat.com> References: <1027701923.3148.10.camel@spc9.esa.lanl.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <1027701923.3148.10.camel@spc9.esa.lanl.gov>; from elenstev@mesatop.com on Fri, Jul 26, 2002 at 10:45:23AM -0600 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 898 Lines: 22 Hi, On Fri, Jul 26, 2002 at 10:45:23AM -0600, Steven Cole wrote: > I found that dbench gives significantly lower numbers when > the partition on which it is run is mounted as ext3. Yes, especially with ext3 using its default 5-second commit intervals and ext2 using 30 second timeouts for its own bdflush. dbench does a lot of IO to temporary files, writing large amounts of data and then shortly deleting it. If it can run fast enough to delete the data before it hits disk, it goes _much_ faster, so you end up measuring cache speed and not disk speed. ext3 is particulary hurt by that given its shorted default commit timeouts. Cheers, Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/