Commit 0989c41b authored by Max Gurtovoy's avatar Max Gurtovoy Committed by Michael S. Tsirkin
Browse files

virtio-blk: add num_request_queues module parameter 



Sometimes a user would like to control the amount of request queues to
be created for a block device. For example, for limiting the memory
footprint of virtio-blk devices.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarMax Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20210902204622.54354-1-mgurtovoy@nvidia.com


Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 02746e26

drivers/block/virtio_blk.c

+22 −1
Original line number Diff line number Diff line
@@ -30,6 +30,25 @@ 
#define VIRTIO_BLK_INLINE_SG_CNT	2

#endif



static int virtblk_queue_count_set(const char *val,

		const struct kernel_param *kp)

{

	return param_set_uint_minmax(val, kp, 1, nr_cpu_ids);

}



static const struct kernel_param_ops queue_count_ops = {

	.set = virtblk_queue_count_set,

	.get = param_get_uint,

};



static unsigned int num_request_queues;

module_param_cb(num_request_queues, &queue_count_ops, &num_request_queues,

		0644);

MODULE_PARM_DESC(num_request_queues,

		 "Limit the number of request queues to use for blk device. "

		 "0 for no limit. "

		 "Values > nr_cpu_ids truncated to nr_cpu_ids.");



static int major;

static DEFINE_IDA(vd_index_ida);
@@ -553,7 +572,9 @@ static int init_vq(struct virtio_blk *vblk) 
	if (err)

		num_vqs = 1;



	num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs);

	num_vqs = min_t(unsigned int,

			min_not_zero(num_request_queues, nr_cpu_ids),

			num_vqs);



	vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);

	if (!vblk->vqs)