Commit 511a2699 authored by Paolo Valente's avatar Paolo Valente Committed by Jens Axboe
Browse files

block, bfq: let also stably merged queues enjoy weight raising 



Merged bfq_queues are kept out of weight-raising (low-latency)
mechanisms. The reason is that these queues are usually created for
non-interactive and non-soft-real-time tasks. Yet this is not the case
for stably-merged queues. These queues are merged just because they
are created shortly after each other. So they may easily serve the I/O
of an interactive or soft-real time application, if the application
happens to spawn multiple processes.

To address this issue, this commits lets also stably-merged queued
enjoy weight raising.

Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20210619140948.98712-2-paolo.valente@linaro.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 76a80408

block/bfq-iosched.c

+14 −1
Original line number Diff line number Diff line
@@ -1729,10 +1729,23 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, 
		bfqq->entity.new_weight == 40;

	*interactive = !in_burst && idle_for_long_time &&

		bfqq->entity.new_weight == 40;

	/*

	 * Merged bfq_queues are kept out of weight-raising

	 * (low-latency) mechanisms. The reason is that these queues

	 * are usually created for non-interactive and

	 * non-soft-real-time tasks. Yet this is not the case for

	 * stably-merged queues. These queues are merged just because

	 * they are created shortly after each other. So they may

	 * easily serve the I/O of an interactive or soft-real time

	 * application, if the application happens to spawn multiple

	 * processes. So let also stably-merged queued enjoy weight

	 * raising.

	 */

	wr_or_deserves_wr = bfqd->low_latency &&

		(bfqq->wr_coeff > 1 ||

		 (bfq_bfqq_sync(bfqq) &&

		  bfqq->bic && (*interactive || soft_rt)));

		  (bfqq->bic || RQ_BIC(rq)->stably_merged) &&

		   (*interactive || soft_rt)));



	/*

	 * Using the last flag, update budget and check whether bfqq