Re: [PATCH V2 4/8] block: null_blk: introduce module parameter of 'g_global_tags'

[Omar Sandoval]

On Mon, Feb 05, 2018 at 11:20:31PM +0800, 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=1 
> 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: Arun Easi 
> Cc: Omar Sandoval ,
> Cc: "Martin K. Petersen" ,
> Cc: James Bottomley ,
> Cc: Christoph Hellwig ,
> Cc: Don Brace 
> Cc: Kashyap Desai 
> Cc: Peter Rivera 
> Cc: Mike Snitzer 
> Tested-by: Laurence Oberman 
> Reviewed-by: Hannes Reinecke 

The module parameter is just called "global_tags", not "g_global_tags",
right? The subject should say the former.

Otherwise,

Reviewed-by: Omar Sandoval 

> Signed-off-by: Ming Lei 
> ---
>  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)
> -- 
> 2.9.5
> 

RE: [PATCH V2 4/8] block: null_blk: introduce module parameter of 'g_global_tags'

[Don Brace]

> 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=1
> 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.
> 
I am getting 1.1M IOPS for both cases.

Tested-by: Don Brace 

[PATCH V2 4/8] block: null_blk: introduce module parameter of 'g_global_tags'

[Ming Lei]

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=1 
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: Arun Easi 
Cc: Omar Sandoval ,
Cc: "Martin K. Petersen" ,
Cc: James Bottomley ,
Cc: Christoph Hellwig ,
Cc: Don Brace 
Cc: Kashyap Desai 
Cc: Peter Rivera 
Cc: Mike Snitzer 
Tested-by: Laurence Oberman 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Ming Lei 
---
 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)
-- 
2.9.5