Introduces parameter of 'g_host_tags' for testing hostwide tags. Not observe performance drop in the following test: 1) no 'host_tags', hw queue depth is 16, and 1 hw queue modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 host_tags=0 submit_queues=1 hw_queue_depth=16 2) 'host_tags', global hw queue depth is 16, and 8 hw queues modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 host_tags=1 submit_queues=8 hw_queue_depth=16 3) fio test command: fio --bs=4k --ioengine=libaio --iodepth=16 --filename=/dev/nullb0:/dev/nullb1:/dev/nullb2:/dev/nullb3 --direct=1 --runtime=30 --numjobs=16 --rw=randread --name=test --group_reporting --gtod_reduce=1 Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- drivers/block/null_blk_main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c index 447d635c79a2..3c04446f3649 100644 --- a/drivers/block/null_blk_main.c +++ b/drivers/block/null_blk_main.c @@ -91,6 +91,10 @@ static int g_submit_queues = 1; module_param_named(submit_queues, g_submit_queues, int, 0444); MODULE_PARM_DESC(submit_queues, "Number of submission queues"); +static int g_host_tags = 0; +module_param_named(host_tags, g_host_tags, int, S_IRUGO); +MODULE_PARM_DESC(host_tags, "All submission queues share one tags"); + static int g_home_node = NUMA_NO_NODE; module_param_named(home_node, g_home_node, int, 0444); MODULE_PARM_DESC(home_node, "Home node for the device"); @@ -1554,6 +1558,8 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set) set->flags = BLK_MQ_F_SHOULD_MERGE; if (g_no_sched) set->flags |= BLK_MQ_F_NO_SCHED; + if (g_host_tags) + set->flags |= BLK_MQ_F_HOST_TAGS; set->driver_data = NULL; if ((nullb && nullb->dev->blocking) || g_blocking) -- 2.20.1
