Commit 058efe00 authored by Vincent Fu's avatar Vincent Fu Committed by Jens Axboe
Browse files

null_blk: add module parameters for 4 options 



Add as module parameters these options:

memory_backed
discard
mbps
cache_size

Previously these could only be set via configfs.

Still missing is bad_blocks.

The kernel test robot found a documentation formatting issue in v1 of
this patch.

Reported-by: default avatarkernel test robot <lkp@intel.com>
Signed-off-by: default avatarVincent Fu <vincent.fu@samsung.com>
Link: https://lore.kernel.org/r/20220708174943.87787-2-vincent.fu@samsung.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ce11bdf9

Documentation/block/null_blk.rst

+22 −0
Original line number Diff line number Diff line
@@ -72,6 +72,28 @@ submit_queues=[1..nr_cpus]: Default: 1 
hw_queue_depth=[0..qdepth]: Default: 64

  The hardware queue depth of the device.



memory_backed=[0/1]: Default: 0

  Whether or not to use a memory buffer to respond to IO requests



  =  =============================================

  0  Transfer no data in response to IO requests

  1  Use a memory buffer to respond to IO requests

  =  =============================================



discard=[0/1]: Default: 0

  Support discard operations (requires memory-backed null_blk device).



  =  =====================================

  0  Do not support discard operations

  1  Enable support for discard operations

  =  =====================================



cache_size=[Size in MB]: Default: 0

  Cache size in MB for memory-backed device.



mbps=[Maximum bandwidth in MB/s]: Default: 0 (no limit)

  Bandwidth limit for device performance.



Multi-queue specific parameters

-------------------------------

drivers/block/null_blk/main.c

+20 −0
Original line number Diff line number Diff line
@@ -201,6 +201,22 @@ static bool g_use_per_node_hctx; 
module_param_named(use_per_node_hctx, g_use_per_node_hctx, bool, 0444);

MODULE_PARM_DESC(use_per_node_hctx, "Use per-node allocation for hardware context queues. Default: false");



static bool g_memory_backed;

module_param_named(memory_backed, g_memory_backed, bool, 0444);

MODULE_PARM_DESC(memory_backed, "Create a memory-backed block device. Default: false");



static bool g_discard;

module_param_named(discard, g_discard, bool, 0444);

MODULE_PARM_DESC(discard, "Support discard operations (requires memory-backed null_blk device). Default: false");



static unsigned long g_cache_size;

module_param_named(cache_size, g_cache_size, ulong, 0444);

MODULE_PARM_DESC(mbps, "Cache size in MiB for memory-backed device. Default: 0 (none)");



static unsigned int g_mbps;

module_param_named(mbps, g_mbps, uint, 0444);

MODULE_PARM_DESC(mbps, "Limit maximum bandwidth (in MiB/s). Default: 0 (no limit)");



static bool g_zoned;

module_param_named(zoned, g_zoned, bool, S_IRUGO);

MODULE_PARM_DESC(zoned, "Make device as a host-managed zoned block device. Default: false");
@@ -650,6 +666,10 @@ static struct nullb_device *null_alloc_dev(void) 
	dev->irqmode = g_irqmode;

	dev->hw_queue_depth = g_hw_queue_depth;

	dev->blocking = g_blocking;

	dev->memory_backed = g_memory_backed;

	dev->discard = g_discard;

	dev->cache_size = g_cache_size;

	dev->mbps = g_mbps;

	dev->use_per_node_hctx = g_use_per_node_hctx;

	dev->zoned = g_zoned;

	dev->zone_size = g_zone_size;