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block, bfq: readd missing reset of parent-entity service

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The received-service counter needs to be equal to 0 when an entity is
set in service. Unfortunately, commit "block, bfq: fix service being
wrongly set to zero in case of preemption" mistakenly removed the
resetting of this counter for the parent entities of the bfq_queue
being set in service. This commit fixes this issue by resetting
service for parent entities, directly on the expiration of the
in-service bfq_queue.

Fixes: 9fae8dd59f ("block, bfq: fix service being wrongly set to zero in case of preemption")
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Paolo Valente 2018-08-16 18:51:15 +02:00 committed by Jens Axboe
parent df60f6e835
commit 8a511ba5fe
1 changed files with 21 additions and 0 deletions
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21
block/bfq-iosched.c
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@ -3298,6 +3298,27 @@ void bfq_bfqq_expire(struct bfq_data *bfqd,
*/
} else
entity->service = 0;
/*
* Reset the received-service counter for every parent entity.
* Differently from what happens with bfqq->entity.service,
* the resetting of this counter never needs to be postponed
* for parent entities. In fact, in case bfqq may have a
* chance to go on being served using the last, partially
* consumed budget, bfqq->entity.service needs to be kept,
* because if bfqq then actually goes on being served using
* the same budget, the last value of bfqq->entity.service is
* needed to properly decrement bfqq->entity.budget by the
* portion already consumed. In contrast, it is not necessary
* to keep entity->service for parent entities too, because
* the bubble up of the new value of bfqq->entity.budget will
* make sure that the budgets of parent entities are correct,
* even in case bfqq and thus parent entities go on receiving
* service with the same budget.
*/
entity = entity->parent;
for_each_entity(entity)
entity->service = 0;
}
/*