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Commit 277a4a9b authored by Paolo Valente's avatar Paolo Valente Committed by Jens Axboe
Browse files

block, bfq: give a better name to bfq_bfqq_may_idle 



The actual goal of the function bfq_bfqq_may_idle is to tell whether
it is better to perform device idling (more precisely: I/O-dispatch
plugging) for the input bfq_queue, either to boost throughput or to
preserve service guarantees. This commit improves the name of the
function accordingly.

Tested-by: default avatarHolger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: default avatarOleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9fae8dd5

block/bfq-iosched.c

+8 −8
Original line number Diff line number Diff line
@@ -634,7 +634,7 @@ static bool bfq_differentiated_weights(struct bfq_data *bfqd) 
 * The following function returns true if every queue must receive the

 * same share of the throughput (this condition is used when deciding

 * whether idling may be disabled, see the comments in the function

 * bfq_bfqq_may_idle()).

 * bfq_better_to_idle()).

 *

 * Such a scenario occurs when:

 * 1) all active queues have the same weight,
@@ -3355,7 +3355,7 @@ static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) 
 * issues taken into account are not trivial. We discuss these issues

 * individually while introducing the variables.

 */

static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)

static bool bfq_better_to_idle(struct bfq_queue *bfqq)

{

	struct bfq_data *bfqd = bfqq->bfqd;

	bool rot_without_queueing =
@@ -3588,19 +3588,19 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) 
}



/*

 * If the in-service queue is empty but the function bfq_bfqq_may_idle

 * If the in-service queue is empty but the function bfq_better_to_idle

 * returns true, then:

 * 1) the queue must remain in service and cannot be expired, and

 * 2) the device must be idled to wait for the possible arrival of a new

 *    request for the queue.

 * See the comments on the function bfq_bfqq_may_idle for the reasons

 * See the comments on the function bfq_better_to_idle for the reasons

 * why performing device idling is the best choice to boost the throughput

 * and preserve service guarantees when bfq_bfqq_may_idle itself

 * and preserve service guarantees when bfq_better_to_idle itself

 * returns true.

 */

static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)

{

	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_may_idle(bfqq);

	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_better_to_idle(bfqq);

}



/*
@@ -3686,7 +3686,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) 
	 * may idle after their completion, then keep it anyway.

	 */

	if (bfq_bfqq_wait_request(bfqq) ||

	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {

	    (bfqq->dispatched != 0 && bfq_better_to_idle(bfqq))) {

		bfqq = NULL;

		goto keep_queue;

	}
@@ -4734,7 +4734,7 @@ static void bfq_completed_request(struct bfq_queue *bfqq, struct bfq_data *bfqd) 
					BFQQE_BUDGET_TIMEOUT);

		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&

			 (bfqq->dispatched == 0 ||

			  !bfq_bfqq_may_idle(bfqq)))

			  !bfq_better_to_idle(bfqq)))

			bfq_bfqq_expire(bfqd, bfqq, false,

					BFQQE_NO_MORE_REQUESTS);

	}