Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements

On 15 Sep 2016, at 13:41, Christoph Hellwig [off-list ref] wrote:

On Thu, Sep 15, 2016 at 01:39:11PM +0100, Alex Bligh wrote:

quoted

That's probably right in the case of file-based back ends that
are running on a Linux OS. But gonbdserver for instance supports
(e.g.) Ceph based backends, where each connection might be talking
to a completely separate ceph node, and there may be no cache
consistency between connections.

Yes, if you don't have a cache coherent backend you are generally
screwed with a multiqueue protocol.

I wonder if the ability to support multiqueue should be visible
in the negotiation stage. That would allow the client to refuse
to select multiqueue where it isn't safe.

Wouter?

-- 
Alex Bligh