From: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Date: Tue, 30 Oct 2007 09:40:13 +0000 (+0100)
Subject: Deadline iosched: Fix batching fairness
X-Git-Tag: v2.6.24-rc2~43^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f5d8aa6382eef2b26032c88656270bdae7f0c42;p=pandora-kernel.git

Deadline iosched: Fix batching fairness

After switching data directions, deadline always starts the next batch
from the lowest-sector request.  This gives excessive deadline expiries
and large latency and throughput disparity between high- and low-sector
requests; an order of magnitude in some tests.

This patch changes the batching behaviour so new batches start from the
request whose expiry is earliest.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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