On Sat, 19 Aug 2023 10:18:57 -0400 Willem de Bruijn wrote:

Right. Many devices only allow bringing all queues down at the same time.

Once a descriptor is posted and the ring head is written, there is no
way to retract that. Since waiting for the device to catch up is not
acceptable, the only option is to bring down the queue, right? Which
will imply bringing down the entire device on many devices. Not ideal,
but acceptable short term, imho.

That may be an incentive for vendors to support per-queue
start/stop/alloc/free. Maybe the ones that support RDMA already do?

Are you talking about HW devices, or virt? I thought most HW made 
in the last 10 years should be able to take down individual queues :o