block, bfq: consider also ioprio classes in symmetry detection
authorPaolo Valente <paolo.valente@linaro.org>
Tue, 29 Jan 2019 11:06:29 +0000 (12:06 +0100)
committerJens Axboe <axboe@kernel.dk>
Thu, 31 Jan 2019 19:50:23 +0000 (12:50 -0700)
commit73d58118498b14e4d2f2391105459b997b586ddc
tree71e72676425a3eaa6e6ebe582ce27994d1eafbf2
parent03e565e4204c6cf8687d995de5cafd0341503b4e
block, bfq: consider also ioprio classes in symmetry detection

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>
block/bfq-iosched.c
block/bfq-iosched.h
block/bfq-wf2q.c