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, 27 Aug 2002 18:18:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 27 Aug 2002 18:18:45 -0400 Received: from [212.112.174.180] ([212.112.174.180]:40591 "EHLO prometheus") by vger.kernel.org with ESMTP id ; Tue, 27 Aug 2002 18:18:44 -0400 Date: Wed, 28 Aug 2002 01:23:01 +0200 From: Peter Schuller To: linux-kernel@vger.kernel.org Subject: 53c1010 controller / LF-D200 DVD-RAM causes system lag Message-ID: <20020827232301.GA3181@prometheus.scode.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, I have been experiencing some annoying behavior with an LF-D200 DVD-RAM on my Tekram SCSI controller (SYM53c1010 chipset). I have tried all I can think of except different combinations or hardware which I don't have available. I have been unable to find any information this issues when searching the web. Problem: During heavy access, the entire system becomes "lagged". System CPU usage goes up (load skyrockets); keypresses and keyreleases are missed (missed interrupts?). This happens mostly in bursts, although key events are missed constantly when this happens. The problem is most pronounced when accessing a filesystem on the DVD-RAM; but also present when writing data to the device directly. It does not always happen. I can write a few megs with no problem. Even tens or hundreds of megs. My best guess at the moment is that I start seeing problems when the fs cache fills up and it flushes data to the disk. It does *not* consistently occur when sync:ing though (i.e. I can write, say, 10 meg and do a sync without any noticable problems). Also, as far as I know (but I am not certain) I can write any amount of data to the disk without problems while sync:ing once every 10 seconds or so - assuming the input is coming in more slowly than the speed of the DVD-RAM. I have not experimented a lot with this, but it was my initial observation when writing a tarball to the drive through netcat. I have tried a few different kernels; most recently 2.4.19. I have tried both version 1 and 2 of the sym53c8xx driver. I have a number of SCSI disks, one CD-ROM and one CD-burner on the controller. None of them exhibit any of these problems; it's just the DVD-RAM. The drive shows up as a CD-ROM device (/dev/scd*), and NOT as a regular disk (/dev/sd*). Wheather this is correct I do not know; but I do know that at least some other DVD-RAM:s show up as disks (based on what I've read in HOWTOs). As far as I have been able to tell I do not have any problems with cabling, SCSI resets, etc. AFAIK the symptomes are not consistent with such problems either. Could this be a kernel problem? If so, what can I do to help debug it? What other information should I provide? Thank you, -- / Peter Schuller, InfiDyne Technologies HB PGP userID: 0xE9758B7D or 'Peter Schuller ' Key retrival: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org