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block, bfq: consider also ioprio classes in symmetry detection

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In asymmetric scenarios, i.e., when some bfq_queue or bfq_group needs to
be guaranteed a different bandwidth than other bfq_queues or bfq_groups,
these service guaranteed can be provided only by plugging I/O dispatch,
completely or partially, when the queue in service remains temporarily
empty. A case where asymmetry is particularly strong is when some active
bfq_queues belong to a higher-priority class than some other active
bfq_queues. Unfortunately, this important case is not considered at all
in the code for detecting asymmetric scenarios. This commit adds the
missing logic.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Paolo Valente
2019-01-29 12:06:29 +01:00
committed by Jens Axboe
parent 03e565e420
commit 73d5811849
3 changed files with 59 additions and 47 deletions
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12
block/bfq-wf2q.c
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@@ -44,6 +44,12 @@ static unsigned int bfq_class_idx(struct bfq_entity *entity)
BFQ_DEFAULT_GRP_CLASS - 1;
}
unsigned int bfq_tot_busy_queues(struct bfq_data *bfqd)
{
return bfqd->busy_queues[0] + bfqd->busy_queues[1] +
bfqd->busy_queues[2];
}
static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
bool expiration);
@@ -1513,7 +1519,7 @@ struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
struct bfq_sched_data *sd;
struct bfq_queue *bfqq;
if (bfqd->busy_queues == 0)
if (bfq_tot_busy_queues(bfqd) == 0)
return NULL;
/*
@@ -1665,7 +1671,7 @@ void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bfq_clear_bfqq_busy(bfqq);
bfqd->busy_queues--;
bfqd->busy_queues[bfqq->ioprio_class - 1]--;
if (!bfqq->dispatched)
bfq_weights_tree_remove(bfqd, bfqq);
@@ -1688,7 +1694,7 @@ void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
bfq_activate_bfqq(bfqd, bfqq);
bfq_mark_bfqq_busy(bfqq);
bfqd->busy_queues++;
bfqd->busy_queues[bfqq->ioprio_class - 1]++;
if (!bfqq->dispatched)
if (bfqq->wr_coeff == 1)