Date: Fri, 8 Feb 2008 10:11:51 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Paul Clements <paul.clements@steeleye.com>, linux-kernel@vger.kernel.org,
       nbd-general@lists.sourceforge.net, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH 1/1] NBD: make nbd default to deadline I/O scheduler
Message-Id: <20080208101151.935b575c.akpm@linux-foundation.org>
In-Reply-To: <20080208093341.b4d02e22.randy.dunlap@oracle.com>
References: <47AC87AE.9040408@steeleye.com>
	<20080208093341.b4d02e22.randy.dunlap@oracle.com>
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On Fri, 8 Feb 2008 09:33:41 -0800 Randy Dunlap <randy.dunlap@oracle.com> wrote:

> On Fri, 08 Feb 2008 11:47:42 -0500 Paul Clements wrote:
> 
> > There have been numerous reports of problems with nbd and cfq. Deadline 
> > gives better performance for nbd, anyway, so let's use it by default.

Please define "problems".  If it's just "slowness" then we can live with
that, but I'd hope that Jens is aware and that it's understood.

It it's "hangs" or "oopses" then we panic.

> so what happens with this patch on cfq-only or as-only kernels?

I assume the elevator_init() call fails and the default elevator continues
to be used.  Perhaps an informative printk is needed.

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