On 02/03/2018 05:21 AM, Ming Lei wrote: > This patch introduces the parameter of 'g_global_tags' so that we can > test this feature by null_blk easiy. > > Not see obvious performance drop with global_tags when the whole hw > depth is kept as same: > > 1) no 'global_tags', each hw queue depth is 1, and 4 hw queues > modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 global_tags=0 submit_queues=4 hw_queue_depth=1 > > 2) 'global_tags', global hw queue depth is 4, and 4 hw queues > modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1 global_tags=0 submit_queues=4 hw_queue_depth=4 > > 3) fio test done in above two settings: > fio --bs=4k --size=512G --rw=randread --norandommap --direct=1 --ioengine=libaio --iodepth=4 --runtime=$RUNTIME --group_reporting=1 --name=nullb0 --filename=/dev/nullb0 --name=nullb1 --filename=/dev/nullb1 --name=nullb2 --filename=/dev/nullb2 --name=nullb3 --filename=/dev/nullb3 > > 1M IOPS can be reached in both above tests which is done in one VM. > > Cc: Hannes Reinecke <hare@xxxxxxx> > Cc: Arun Easi <arun.easi@xxxxxxxxxx> > Cc: Omar Sandoval <osandov@xxxxxx>, > Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>, > Cc: James Bottomley <james.bottomley@xxxxxxxxxxxxxxxxxxxxx>, > Cc: Christoph Hellwig <hch@xxxxxx>, > Cc: Don Brace <don.brace@xxxxxxxxxxxxx> > Cc: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx> > Cc: Peter Rivera <peter.rivera@xxxxxxxxxxxx> > Cc: Laurence Oberman <loberman@xxxxxxxxxx> > Cc: Mike Snitzer <snitzer@xxxxxxxxxx> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > drivers/block/null_blk.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c > index 287a09611c0f..ad0834efad42 100644 > --- a/drivers/block/null_blk.c > +++ b/drivers/block/null_blk.c > @@ -163,6 +163,10 @@ static int g_submit_queues = 1; > module_param_named(submit_queues, g_submit_queues, int, S_IRUGO); > MODULE_PARM_DESC(submit_queues, "Number of submission queues"); > > +static int g_global_tags = 0; > +module_param_named(global_tags, g_global_tags, int, S_IRUGO); > +MODULE_PARM_DESC(global_tags, "All submission queues share one tags"); > + > static int g_home_node = NUMA_NO_NODE; > module_param_named(home_node, g_home_node, int, S_IRUGO); > MODULE_PARM_DESC(home_node, "Home node for the device"); > @@ -1622,6 +1626,8 @@ 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_global_tags) > + set->flags |= BLK_MQ_F_GLOBAL_TAGS; > set->driver_data = NULL; > > if ((nullb && nullb->dev->blocking) || g_blocking) > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
