From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 11 Dec 2001 18:43:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 11 Dec 2001 18:43:46 -0500 Received: from 12-234-19-19.client.attbi.com ([12.234.19.19]:13325 "HELO ocean.lucon.org") by vger.kernel.org with SMTP id ; Tue, 11 Dec 2001 18:43:34 -0500 Date: Tue, 11 Dec 2001 15:43:31 -0800 From: "H . J . Lu" To: Linux 1394 Cc: linux kernel , andrea@suse.de Subject: Re: Slow Disk I/O with QPS M3 80GB HD Message-ID: <20011211154331.A32433@lucon.org> In-Reply-To: <20011210203452.A3250@lucon.org> <20011210235708.A17743@lucon.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20011210235708.A17743@lucon.org>; from hjl@lucon.org on Mon, Dec 10, 2001 at 11:57:08PM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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. H.J.