Commit 875feb63 authored Jan 06, 2010 by Divyesh Shah Committed by Jens Axboe Jan 11, 2010

cfq-iosched: Respect ioprio_class when preempting



In cfq_should_preempt(), we currently allow some cases where a non-RT request
can preempt an ongoing RT cfqq timeslice. This should not happen.
Examples include:

o A sync_noidle wl type non-RT request pre-empting a sync_noidle wl type cfqq
  on which we are idling.
o Once we have per-cgroup async queues, a non-RT sync request pre-empting a RT
  async cfqq.

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

parent 7af92f87

block/cfq-iosched.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -3076,6 +3076,12 @@ cfq_should_preempt(struct cfq_data cfqd, struct cfq_queue new_cfqq,
		if (cfq_class_idle(cfqq))
		return true;

		/*
		* Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
		*/
		if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
		return false;

		/*
		* if the new request is sync, but the currently running queue is
		* not, let the sync request have priority.