Commit bf572256 authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
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[PATCH] cfq-iosched: improve queue preemption 



Don't touch the current queues, just make sure that the wanted queue
is selected next. Simplifies the logic.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent dc72ef4a

block/cfq-iosched.c

+8 −6
Original line number Diff line number Diff line
@@ -1539,17 +1539,19 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, 
 */

static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)

{

	struct cfq_queue *__cfqq, *next;



	list_for_each_entry_safe(__cfqq, next, &cfqd->cur_rr, cfq_list)

		cfq_resort_rr_list(__cfqq, 1);

	cfq_slice_expired(cfqd, 1);



	if (!cfqq->slice_left)

		cfqq->slice_left = cfq_prio_to_slice(cfqd, cfqq) / 2;



	/*

	 * Put the new queue at the front of the of the current list,

	 * so we know that it will be selected next.

	 */

	BUG_ON(!cfq_cfqq_on_rr(cfqq));

	list_move(&cfqq->cfq_list, &cfqd->cur_rr);



	cfqq->slice_end = cfqq->slice_left + jiffies;

	cfq_slice_expired(cfqd, 1);

	__cfq_set_active_queue(cfqd, cfqq);

}



/*