From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Date: Tue, 26 Apr 2011 16:57:59 +0000 (-0400)
Subject: xen/blkback: Move the plugging/unplugging to a higher level.
X-Git-Tag: v3.0-rc1~162^2~16^2~26
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=97961ef46b9b5a6a7c918a38b898a7b3e49869f4;p=pandora-kernel.git

xen/blkback: Move the plugging/unplugging to a higher level.

We used to the plug/unplug on the submit_bio. But that means
if within a stream of WRITE, WRITE, WRITE,...,WRITE we have
one READ, it could stall the pipeline (as the 'submio_bio'
could trigger the unplug_fnc to be called and stall/sync
when doing the READ). Instead we want to move the unplugging
when the whole (or as a much as possible) ring buffer has been
processed. This also eliminates us doing plug/unplug for
each request.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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