tree 62afdbc8eb90393e768d0770c20fc9b2c7e8e042
parent 02246c41171097ceab3246f6dc251ac89de6004b
author Divyesh Shah <dpshah@google.com> 1270798197 +0200
committer Jens Axboe <jens.axboe@oracle.com> 1270798197 +0200

cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch

When CFQ dispatches requests forcefully due to a barrier or changing iosched,
it runs through all cfqq's dispatching requests and then expires each queue.
However, it does not activate a cfqq before flushing its IOs resulting in
using stale values for computing slice_used.
This patch fixes it by calling activate queue before flushing reuqests from
each queue.

This is useful mostly for barrier requests because when the iosched is changing
it really doesnt matter if we have incorrect accounting since we're going to
break down all structures anyway.

We also now expire the current timeslice before moving on with the dispatch
to accurately account slice used for that cfqq.

Signed-off-by: Divyesh Shah<dpshah@google.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>