From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 12 Dec 2001 03:29:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 12 Dec 2001 03:29:42 -0500 Received: from penguin.e-mind.com ([195.223.140.120]:63508 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Wed, 12 Dec 2001 03:29:29 -0500 Date: Wed, 12 Dec 2001 09:29:54 +0100 From: Andrea Arcangeli To: "H . J . Lu" Cc: Linux 1394 , linux kernel Subject: Re: Slow Disk I/O with QPS M3 80GB HD Message-ID: <20011212092954.N4801@athlon.random> In-Reply-To: <20011210203452.A3250@lucon.org> <20011210235708.A17743@lucon.org> <20011211154331.A32433@lucon.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.12i In-Reply-To: <20011211154331.A32433@lucon.org>; from hjl@lucon.org on Tue, Dec 11, 2001 at 03:43:31PM -0800 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 11, 2001 at 03:43:31PM -0800, H . J . Lu wrote: > On Mon, Dec 10, 2001 at 11:57:08PM -0800, H . J . Lu wrote: > > On Mon, Dec 10, 2001 at 08:34:52PM -0800, H . J . Lu wrote: > > > I have a very strange problem. The disk I/O of my QPS M3 80GB HD is > > > very slow under 2.4.10 and above. I got like 1.77 MB/s from hdparm. > > > But under 2.4.9, I got 14 MB/s on the same hardware. A 30GB HD has > > > consistent I/O performance under 2.4.9 and above on the same bus. Has > > > anyone else seen this? Does anyone have a large (>= 80GB) 1394 HD? > > > > > > > I did a binary search. 2.4.10-pre10 is the last good kernel. I got > > > > # hdparm -t /dev/sda > > > > /dev/sda: > > Timing buffered disk reads: 64 MB in 4.40 seconds = 14.55 MB/sec > > > > Even since 2.4.10-pre11 up to 2.4.16, I got about 1.77 MB/sec on the > > same hardware. However, I don't have problems with 80GB IDE HD. Has > > anyone seen I/O problems on large (>= 80GB) SCSI HD or HD with SCSI > > emulation? > > I tracked own the problem to 40_blkdev-pagecache-17 in the 2.4.10 > pre10aa1 patch. When it is applied, the disk I/O on some drives become > very slow. It not only happens to my 80GB 1394 HD, but also the second > IDE drive. Before the patch > > # hdparm -t /dev/hdd > > /dev/hdd: > Timing buffered disk reads: 64 MB in 8.02 seconds = 7.98 MB/sec > > After the patch > > # hdparm -t /dev/hdd > > /dev/hdd: > Timing buffered disk reads: 64 MB in 21.09 seconds = 3.03 MB/sec > > The slow down is not as bad as 1394. But it is still very significant. > I couldn't figure out why it only affects certain drives. do you have a 4k filesystm mounted on /dev/hdd? if so then you will get the same performance with latest 2.4 (precisely after 2.4.1). Andrea