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Commit 6c80731c authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe
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cfq-iosched: Reorder checks in cfq_should_preempt() 



Move check for preemption by rt class up. There is no functional change
but it makes arguing about conditions simpler since we can be sure both
cfq queues are from the same ioprio class.

Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJan Kara <jack@suse.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent e795421e

block/cfq-iosched.c

+7 −6
Original line number Diff line number Diff line
@@ -3959,6 +3959,13 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 
	if (cfq_slice_used(cfqq))

		return true;



	/*

	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.

	 */

	if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))

		return true;



	WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);

	/* Allow preemption only if we are idling on sync-noidle tree */

	if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&

	    cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
@@ -3973,12 +3980,6 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 
	if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)

		return true;



	/*

	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.

	 */

	if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))

		return true;



	/* An idle queue should not be idle now for some reason */

	if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))

		return true;