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>

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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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86

block/bfq-iosched.c

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8

block/bfq-iosched.h

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12

block/bfq-wf2q.c

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