Re: [Qemu-devel] [PATCH v5] vhost-user: add multi queue support

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, May 28, 2015 at 09:23:06AM +0800, Ouyang Changchun wrote:
> Based on patch by Nikolay Nikolaev:
> Vhost-user will implement the multi queue support in a similar way
> to what vhost already has - a separate thread for each queue.
> To enable the multi queue functionality - a new command line parameter
> "queues" is introduced for the vhost-user netdev.
> 
> Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>

So testing turned up a significant issue with the protocol extension in this
one.  Specifically, remote has no idea how many queues guest actually
wants to use (it's dynamic, guest changes this at any time).
We need support for enabling and disabling queues dynamically.

Given we are past hard freeze, and given no one uses this yet
(dpdk upstream did not merge supporting protocol),
I think the best thing to do is to disable this functionality for 2.4.
I will send a patch to do this shortly.

I do think this support is important, so me and Marcel will try work on
it in the coming several weeks, and to come up with a better protocol.
I hope we'll be able to have a replacement ready by the time 2.4
is released and 2.5 development opens up so it can be merged first
thing.

It also seems that it will also align better with the plans to use this
in upstream dpdk.

-- 
MST