From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Ledford Subject: Re: ide-scsi cmd_per_lun Date: Tue, 9 Jul 2002 18:00:14 -0400 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20020709180014.A12706@redhat.com> References: <000701c2278e$2dc723a0$e0019d89@cybernetics.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <000701c2278e$2dc723a0$e0019d89@cybernetics.com>; from tonyb@cybernetics.com on Tue, Jul 09, 2002 at 05:18:31PM -0400 List-Id: linux-scsi@vger.kernel.org To: Tony Battersby Cc: linux-scsi@vger.kernel.org On Tue, Jul 09, 2002 at 05:18:31PM -0400, Tony Battersby wrote: > > The problem boils down to the fact that ide-scsi relies on the mid-level > (old eh) to do the auto-sense. I was able to work around this problem by > setting cmd_per_lun: 1 in ide-scsi.h (vanilla 2.4.17). Doing this caused > the request sense command to make it to the drive before any other command > could sneak in and reset the sense data. Can anyone tell me if this is a > good solution? It is the appropriate setting for any driver that doesn't automatically request sense itself on check condition status returns. It does not solve the problem for tagged queue enabled devices though since they don't honor this field and will loose sense information, so in reality any driver that doesn't auto request sense data is broken to some extent. The new eh code requires that drivers auto request sense, so this is actually likely to be really broken in 2.5 at the moment since the old eh code is now gone. > Looking at the 2.4.19-rc1 source, I see an additional field > "can_queue: 10" in the template. Should this be changed too? I cannot use > 2.4.19 for the moment, so I can't experiment with it. No, this is only for the host wide queue, so if you had 5 ide-scsi devices that showed up, this limits the total number of commands sent to the ide-scsi driver to 10, which would be 2 each. Obviously, this is different than what you are trying to set and is only limited by what the ide-scsi driver can actually handle in terms of outstanding commands at a time. > > Thanks, > Anthony J. Battersby > Cybernetics > > - > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Doug Ledford 919-754-3700 x44233 Red Hat, Inc. 1801 Varsity Dr. Raleigh, NC 27606