block, bfq: save & resume weight on a queue merge/split (fffca087) · Commits · 戴 / test

bfq saves the state of a queue each time a merge occurs, to be able to resume such a state when the queue is associated again with its original process, on a split. Unfortunately bfq does not save & restore also the weight of the queue. If the weight is not correctly resumed when the queue is recycled, then the weight of the recycled queue could differ from the weight of the original queue. This commit adds the missing save & resume of the weight. Tested-by:

Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by:

Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by:

Francesco Pollicino <fra.fra.800@gmail.com> Signed-off-by:

Paolo Valente <paolo.valente@linaro.org> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/bfq-iosched.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1028,6 +1028,7 @@ bfq_bfqq_resume_state(struct bfq_queue bfqq, struct bfq_data bfqd,
		else
		bfq_clear_bfqq_IO_bound(bfqq);

		bfqq->entity.new_weight = bic->saved_weight;
		bfqq->ttime = bic->saved_ttime;
		bfqq->wr_coeff = bic->saved_wr_coeff;
		bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
		@@ -2502,6 +2503,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
		if (!bic)
		return;

		bic->saved_weight = bfqq->entity.orig_weight;
		bic->saved_ttime = bfqq->ttime;
		bic->saved_has_short_ttime = bfq_bfqq_has_short_ttime(bfqq);
		bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);

block/bfq-iosched.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -404,6 +404,15 @@ struct bfq_io_cq {
		*/
		bool was_in_burst_list;

		/*
		* Save the weight when a merge occurs, to be able
		* to restore it in case of split. If the weight is not
		* correctly resumed when the queue is recycled,
		* then the weight of the recycled queue could differ
		* from the weight of the original queue.
		*/
		unsigned int saved_weight;

		/*
		* Similar to previous fields: save wr information.
		*/

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