Commit faad87df authored by Mike Snitzer's avatar Mike Snitzer
Browse files

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: default avatarMike Snitzer <snitzer@redhat.com>
parent c91852ff

drivers/md/dm.c

+25 −2
Original line number Diff line number Diff line
@@ -233,6 +233,12 @@ static bool use_blk_mq = true; 
static bool use_blk_mq = false;

#endif



#define DM_MQ_NR_HW_QUEUES 1

#define DM_MQ_QUEUE_DEPTH 2048



static unsigned dm_mq_nr_hw_queues = DM_MQ_NR_HW_QUEUES;

static unsigned dm_mq_queue_depth = DM_MQ_QUEUE_DEPTH;



bool dm_use_blk_mq(struct mapped_device *md)

{

	return md->use_blk_mq;
@@ -303,6 +309,17 @@ unsigned dm_get_reserved_rq_based_ios(void) 
}

EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);



static unsigned dm_get_blk_mq_nr_hw_queues(void)

{

	return __dm_get_module_param(&dm_mq_nr_hw_queues, 1, 32);

}



static unsigned dm_get_blk_mq_queue_depth(void)

{

	return __dm_get_module_param(&dm_mq_queue_depth,

				     DM_MQ_QUEUE_DEPTH, BLK_MQ_MAX_DEPTH);

}



static int __init local_init(void)

{

	int r = -ENOMEM;
@@ -2695,10 +2712,10 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) 


	memset(&md->tag_set, 0, sizeof(md->tag_set));

	md->tag_set.ops = &dm_mq_ops;

	md->tag_set.queue_depth = BLKDEV_MAX_RQ;

	md->tag_set.queue_depth = dm_get_blk_mq_queue_depth();

	md->tag_set.numa_node = NUMA_NO_NODE;

	md->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;

	md->tag_set.nr_hw_queues = 1;

	md->tag_set.nr_hw_queues = dm_get_blk_mq_nr_hw_queues();

	if (md_type == DM_TYPE_REQUEST_BASED) {

		/* make the memory for non-blk-mq clone part of the pdu */

		md->tag_set.cmd_size = sizeof(struct dm_rq_target_io) + sizeof(struct request);
@@ -3669,6 +3686,12 @@ MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools" 
module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");



module_param(dm_mq_nr_hw_queues, uint, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(dm_mq_nr_hw_queues, "Number of hardware queues for request-based dm-mq devices");



module_param(dm_mq_queue_depth, uint, S_IRUGO | S_IWUSR);

MODULE_PARM_DESC(dm_mq_queue_depth, "Queue depth for request-based dm-mq devices");



MODULE_DESCRIPTION(DM_NAME " driver");

MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");

MODULE_LICENSE("GPL");

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