From: Steven Hayter <steven@hayter.me.uk>
To: Dan Aloni <da-x@monatomic.org>
Cc: Linux Kernel List <linux-kernel@vger.kernel.org>,
linux-scsi@vger.kernel.org, Mike Christie <michaelc@cs.wisc.edu>
Subject: Re: [PATCH] scsi_execute_async() should add to the tail of the queue
Date: Wed, 20 Dec 2006 20:40:29 +0000 [thread overview]
Message-ID: <45899FBD.9070803@hayter.me.uk> (raw)
In-Reply-To: <20061219000234.GA5330@localdomain>
Dan Aloni wrote:
> Hello,
>
> scsi_execute_async() has replaced scsi_do_req() a few versions ago,
> but it also incurred a change of behavior. I noticed that over-queuing
> a SCSI device using that function causes I/Os to be starved from
> low-level queuing for no justified reason.
>
> I think it makes much more sense to perserve the original behaviour
> of scsi_do_req() and add the request to the tail of the queue.
As far as I'm aware the way in which scsi_do_req() was to insert at the
head of the queue, leading to projects like SCST to come up with
scsi_do_req_fifo() as queuing multiple commands using scsi_do_req() with
constant head insertion might lead to out of order execution.
Just thought I'd throw some light on the history and what others have
done in the past.
Steve
next prev parent reply other threads:[~2006-12-20 21:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-19 0:02 [PATCH] scsi_execute_async() should add to the tail of the queue Dan Aloni
2006-12-20 20:40 ` Steven Hayter [this message]
2006-12-21 7:12 ` Dan Aloni
-- strict thread matches above, loose matches on Subject: below --
2006-12-19 8:35 Dan Aloni
2006-12-19 10:03 ` Arjan van de Ven
2006-12-19 10:34 ` Dan Aloni
2006-12-20 23:50 ` Jeremy Linton
2006-12-19 11:26 ` Jens Axboe
2006-12-19 18:34 ` Jon Escombe
2006-12-19 18:44 ` Jens Axboe
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