From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Tony Battersby" <tonyb@cybernetics.com>
Subject: RE: [PATCH RFC 0/4] use scatter lists for all block pc	requests	and simplify hw handlers
Date: Tue, 7 Jun 2005 09:34:00 -0400
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To: dougg@torque.net, 'James Bottomley' <James.Bottomley@SteelEye.com>
Cc: 'Mike Christie' <michaelc@cs.wisc.edu>, 'device-mapper development' <dm-devel@redhat.com>, 'linux-scsi' <linux-scsi@vger.kernel.org>, 'Jens Axboe' <axboe@suse.de>, LIRANS@il.ibm.com

> James Bottomley wrote:
> > Well ... while I've got your attention, the only complexity I see to
> > converting sg is the hd->iovec_count != 0 case, which is doing
vectored
> > SG from user land.
> >
> > This can be implemented (basically you do multiple bio attachment to
a
> > request), and probably in the block layer (since block SG_IO would
then
> > pick up the capability).
> >
> > How important is this functionality?  Are there any applications
using
> > it?
>
> I don't think it is important and I'm not aware of any
> real world applications that are using it. Naturally,
> I will find out if that is actually true after it
> gets removed.

My company (Cybernetics) sells several products that run embedded Linux
which use the userspace scatter-gather capability of the SG driver.
They are still running the 2.4 kernel series, but we will probably
switch to 2.6 at some point.

Anthony J. Battersby
Cybernetics