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Commit 0c534e0a authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
Browse files

cfq-iosched: sort RT queues into the rbtree 



Currently CFQ does a linked insert into the current list for RT
queues. We can just factor the class into the rb insertion,
and then we don't have to treat RT queues in a special way. It's
faster, too.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent cc09e299

block/cfq-iosched.c

+12 −15
Original line number Diff line number Diff line
@@ -471,7 +471,16 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
		parent = *p;

		__cfqq = rb_entry(parent, struct cfq_queue, rb_node);



		if (rb_key < __cfqq->rb_key)

		/*

		 * sort RT queues first, we always want to give

		 * preference to them. after that, sort on the next

		 * service time.

		 */

		if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))

			p = &(*p)->rb_left;

		else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))

			p = &(*p)->rb_right;

		else if (rb_key < __cfqq->rb_key)

			p = &(*p)->rb_left;

		else {

			p = &(*p)->rb_right;
@@ -490,7 +499,6 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, 
static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)

{

	struct cfq_data *cfqd = cfqq->cfqd;

	struct list_head *n;



	/*

	 * Resorting requires the cfqq to be on the RR list already.
@@ -500,25 +508,14 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) 


	list_del_init(&cfqq->cfq_list);



	if (cfq_class_rt(cfqq)) {

		/*

		 * At to the front of the current list, but behind other

		 * RT queues.

		 */

		n = &cfqd->cur_rr;

		while (n->next != &cfqd->cur_rr)

			if (!cfq_class_rt(cfqq))

				break;



		list_add(&cfqq->cfq_list, n);

	} else if (cfq_class_idle(cfqq)) {

	if (cfq_class_idle(cfqq)) {

		/*

		 * IDLE goes to the tail of the idle list

		 */

		list_add_tail(&cfqq->cfq_list, &cfqd->idle_rr);

	} else {

		/*

		 * So we get here, ergo the queue is a regular best-effort queue

		 * RT and BE queues, sort into the rbtree

		 */

		cfq_service_tree_add(cfqd, cfqq);

	}