From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 10 Mar 2003 06:21:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 10 Mar 2003 06:21:03 -0500 Received: from krusty.dt.E-Technik.Uni-Dortmund.DE ([129.217.163.1]:35087 "EHLO mail.dt.e-technik.uni-dortmund.de") by vger.kernel.org with ESMTP id ; Mon, 10 Mar 2003 06:21:02 -0500 Date: Mon, 10 Mar 2003 12:31:39 +0100 From: Matthias Andree To: Douglas Gilbert Cc: linux-kernel@vger.kernel.org Subject: Re: 2.4: high system load with SG_IO on IDE-SCSI: PIO? Message-ID: <20030310113139.GA6101@merlin.emma.line.org> Mail-Followup-To: Douglas Gilbert , linux-kernel@vger.kernel.org References: <3E6C2436.1000007@torque.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3E6C2436.1000007@torque.net> User-Agent: Mutt/1.5.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 10 Mar 2003, Douglas Gilbert wrote: > The experience from the early 2.4 series was that the ide > subsystem was too aggressive in its DMA settings for CD/DVD > burners. [My experience with scsi devices is that disks have > much better target implementations (i.e. more robust) than > CD/DVD devices and scanners.] Later versions of the 2.4 series ATAPI scanners? Cool stuff. Seriously, there is cheap ATAPI junk and there is serious stuff. > are a lot more conservative in their speed treatment of ATAPI > devices. The robustness comes at the expense of system load. Well, some amount of configurability would be nice for the ones of us who have working ATAPI hardware. Even if it's a boot-time parameter like "hdc=atapidma" or something (that's what FreeBSD does, with the boot-time variable hw.ata.atapi_dma, it defaults to 0 but drop hw.ata.atapi_dma="1" into /boot/loader.conf.local and have the machine talk DMA to ATAPI stuff). Am I missing such an option? I am currently facing the choice "switch to some other OS that talks DMA to my CD-writer" or "buy an ATAPI-SCSI-converter" (which is above 100 EUR). I'd like to have a third option to choose, tell the kernel "forget your sorrows and talk DMA." -- it could use a (user-space) whitelist, say "Plextor CD-R 4824TA 1.04 is fine". > ** Even though a CD writer appears as /dev/scd0 with ide-scsi > appropriately configured, the hdparm command can still be used > on /dev/hdd (for example, if the writer is the slave on the > second IDE bus). /sbin/hdparm -X66 -d1 -u1 happens at boot time (for hdc) -- still I'm facing unreasonably high system load when writing a CD. -- Matthias Andree