Subject: request->ioprio
From: Fernando Luis =?ISO-8859-1?Q?V=E1zquez?= Cao 
	<fernando@oss.ntt.co.jp>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: rusty@rustcorp.com.au, linux-kernel@vger.kernel.org
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Organization: NTT Open Source Software Center
Date: Wed, 06 Aug 2008 18:32:38 +0900
Message-Id: <1218015158.4419.58.camel@sebastian.kern.oss.ntt.co.jp>
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(CCing LKML)

Hi Jens, Rusty,

Trying to implement i/o tracking all the way up to the page cache (so
that cfq and the future cgroup-based I/O controllers can schedule
buffered I/O properly) I noticed that struct request's ioprio is
initialized but never used for I/O scheduling purposes. Indeed there
seems to be one single user of this member: virtio_blk. Virtio uses
struct request's ioprio in the request() function of the virtio block
driver, which just copies the ioprio value to the output header of
virtblk_req.

Is this the intended use of struct request's ioprio? Is it OK for device
drivers to use it? If the answer two the previous to questions is no I
would like to send some clean-up patches.

- Fernando

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