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Date: Wed, 6 Nov 2002 18:33:25 -0500
From: Adam Kropelin <akropel1@rochester.rr.com>
To: Patrick Mansfield <patmans@us.ibm.com>
Cc: Jens Axboe <axboe@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: 2.5.46: ide-cd cdrecord (almost) success report
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On Wed, Nov 06, 2002 at 10:11:44AM -0800, Patrick Mansfield wrote:
> On Wed, Nov 06, 2002 at 10:56:56AM -0500, Adam Kropelin wrote:
> > On Wed, Nov 06, 2002 at 08:22:23AM +0100, Jens Axboe wrote:
> > > On Tue, Nov 05 2002, Adam Kropelin wrote:
> > > > Still without coaster I tried one more thing...
> > > > 'dd if=/dev/zero of=foo bs=1M' in parallel with another burn. That one
> > > > did it in. ;) I'm running ext3 and the writeout load totally killed
> > > > burn, which isn't surprising. I was asking for it, I know. What happened
> > > 
> > > Really, this should work. The deadline scheduler should handle this just
> > > fine in fact. Which device is your burner and which device is the hard
> > > drive? It sounds like a bug.
> > 
> > Hard disk is sdc on onboard AIC7xxx.
> > Writer is hdc, the only device on the secondary onboard IDE channel.
> > All other disks (IDE & SCSI) were idle during the test.
> 
> What queue depth is the AIC setting?
> 
> SCSI in 2.5.x no longer copies the request, so if you have a queue
> depth larger than the allocated requests there might not be
> any free requests left for the blk layer to play with.
> 
> AIC default queue depth is 253 (with 2.5.46 queue depth can be set to 1

Are you talking tcq depth here? Best as I can tell, 2.5.46 defaults to
16. Lowering it to 2 doesn't seem to help.

> queue depth). You can modify .config, or pass boot/module options to
> lower it.

If I've misunderstood you, please clue me in and I'll give it a shot...

--Adam
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