When starting qemu with vhost-user-blk multiqueue(set num-queues to
more than 1), the vhost device will be started/stopped many times
(related to the queue num), as the vhost-user backend doesn't know the
exact number of queues used for this device.
The target have to stop and start the device once got a valid IO queue.
When stoping and starting the vhost device, the backend bdev io device
will be deleted and created repeatly.
If the backend bdev is a distribution system, the cost is large as the
network RTT.
In this patch, add a dummy_io_channel to hold a reference to the io
device, so that the io device will not be deleted.
Change-Id: I5737248ec52bee06342ff0873bb89fd0a51665c2
Signed-off-by: Li Feng <fengli@smartx.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/2020
Community-CI: Broadcom CI
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Xiaodong Liu <xiaodong.liu@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
bcc28e05d1