From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263593AbTL2Qmb (ORCPT ); Mon, 29 Dec 2003 11:42:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263595AbTL2Qmb (ORCPT ); Mon, 29 Dec 2003 11:42:31 -0500 Received: from ncc1701.cistron.net ([62.216.30.38]:50096 "EHLO ncc1701.cistron.net") by vger.kernel.org with ESMTP id S263593AbTL2Qma (ORCPT ); Mon, 29 Dec 2003 11:42:30 -0500 From: "Miquel van Smoorenburg" Subject: Re: Speed drop /dev/sda -> /dev/sda1 -> /dev/vg0/test (3ware/LVM) Date: Mon, 29 Dec 2003 16:42:29 +0000 (UTC) Organization: Cistron Group Message-ID: References: <20031229125412.GA28262@cistron.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Trace: ncc1701.cistron.net 1072716149 25417 62.216.29.200 (29 Dec 2003 16:42:29 GMT) X-Complaints-To: abuse@cistron.nl X-Newsreader: trn 4.0-test76 (Apr 2, 2001) Originator: miquels@cistron-office.nl (Miquel van Smoorenburg) To: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <20031229125412.GA28262@cistron.nl>, Miquel van Smoorenburg wrote: >Hello, > > I'm running Linux 2.6.0 with a 3ware 8506 controller in >hardware RAID5 mode. The RAID5 array is built of 7+1 200 MB SATA >disks. > >Now it appears that more "mappings" on the array have a bad >influence on speed. /dev/sda is the fastest, /dev/sda1 is quite >a bit slower, LVM on /dev/sda is slower yet and LVM on /dev/sda1 >is the slowest. For reference, I just took 2.4.24-pre2, applied the device-mapper patches to it, and re-ran the tests. Base performance on /dev/sda is a bit slower (70 MB/sec vs 80 MB/sec raw writespeed), but speeds on /dev/sda1 and /dev/vg0/test are exactly the same. So it doesn't look like a 3ware driver or LVM issue as those are basically the same between the 2.4 and 2.6 systems. Mike. -- When life hands you lemons, grab the salt and pass the tequila.