From: NeilBrown <neilb@suse.de>
Date: Wed, 19 Sep 2012 02:48:30 +0000 (+1000)
Subject: Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."
X-Git-Tag: v3.6-rc7~29^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a852d7b8a0cf29499905c9243fa6d3fb93898b82;p=pandora-kernel.git

Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."

This reverts commit 895e3c5c58a80bb9e4e05d9ac38b4f30e0f97d80.

While this patch seemed like a good idea and did help some workloads,
it hurts other workloads.
Large sequential O_DIRECT writes were faster,
Small random O_DIRECT writes were slower.

Other changes (batching RAID5 writes) have improved the sequential
writes using a different mechanism, so the net result of this patch
is definitely negative.  So revert it.

Reported-by: Shaohua Li <shli@kernel.org>
Tested-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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