dm: add 'dm_mq_nr_hw_queues' and 'dm_mq_queue_depth' module params
authorMike Snitzer <snitzer@redhat.com>
Thu, 28 Jan 2016 21:52:56 +0000 (16:52 -0500)
committerMike Snitzer <snitzer@redhat.com>
Mon, 22 Feb 2016 17:07:10 +0000 (12:07 -0500)
commitfaad87df4b907605815c711dca613b3e7755e0d9
tree61a265ebab2d4e692649361ea72c2d5716bee69d
parentc91852ff081561d8793d2927e55f5c5deaea6bff
dm: add 'dm_mq_nr_hw_queues' and 'dm_mq_queue_depth' module params

Allow user to change these values via module params or sysfs.

'dm_mq_nr_hw_queues' defaults to 1 (max 32).

'dm_mq_queue_depth' defaults to 2048 (up from 64, which proved far too
small under moderate sized workloads -- the dm-multipath device would
continuously block waiting for tags (requests) to become available).
The maximum is BLK_MQ_MAX_DEPTH (currently 10240).

Keep in mind the total number of pre-allocated requests per
request-based dm-mq device is 'dm_mq_nr_hw_queues' * 'dm_mq_queue_depth'
(currently 2048).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm.c