Date: Tue, 1 Sep 2009 22:31:28 +0200
From: Bruno =?UTF-8?B?UHLDqW1vbnQ=?= <bonbons@linux-vserver.org>
To: Ed Cashin <ecashin@coraid.com>
Cc: apw@canonical.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/1] aoe: ensure we initialise the request_queue
 correctly
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On Tue, 01 September 2009 Ed Cashin <ecashin@coraid.com> wrote:

> On Sat Aug 29 09:43:54 EDT 2009, bonbons@linux-vserver.org wrote:
> ...
> > I finished bisecting the NULL object and ended up at this commit:
> >   cd43e26f071524647e660706b784ebcbefbd2e44
> > 
> >   block: Expose stacked device queues in sysfs
> > 
> >   Currently stacking devices do not have a queue directory in sysfs.
> >   However, many of the I/O characteristics like sector size, maximum
> >   request size, etc. are queue properties.
> > 
> >   This patch enables the queue directory for MD/DM devices.  The
> > elevator code has been modified to deal with queues that do not
> > have an I/O scheduler.
> > 
> >   Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> >   Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> > 
> > 
> > This seems to generate /sys/block/$device/queue and its contents for
> > everyone who is using queues, not just for those queues that have a
> > non-NULL queue->request_fn.
> 
> Thanks much for doing that.  It makes sense that this change would
> have caused it to suddenly matter whether the unused queue is
> initialized.
> 
> The patch looks fine to me.

Would it make sense to fine-tune the values reported by sys-fs in the
queue details so they match with the AoE device (as a separate
enhancement patch)?

Sure the queue itself won't use them, but some user-space tools might
be interested in this data.

I've not checked what information is provided by AoE protocol or can
be deducted from interface MTU.

Bruno
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