Messages in this thread | | | Date | Fri, 9 Apr 2010 09:29:16 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH] cfq-iosched: Fix the incorrect timeslice accounting with forced_dispatch. |
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On Thu, Apr 08 2010, Divyesh Shah wrote: > 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.
Good catch, applied for 2.6.34.
-- Jens Axboe
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