Re: [Qemu-devel] [PATCH 2/2] vhost-user: only seek a reply if needed in set_mem_table

[Maxime Coquelin]

On 09/08/2016 05:15 PM, Michael S. Tsirkin wrote:
> On Thu, Sep 08, 2016 at 10:34:10AM +0200, Maxime Coquelin wrote:
> > The goal of this patch is to only request a sync (reply_ack,
> > or get_features) in set_mem_table only when necessary.
> >
> > It should not be necessary the first time we set the table,
> > or when we add a new regions which hadn't been merged with an
> > existing ones.
>
> I'm not sure I get the second part. If we don't sync,
> can't use of memory by guest bypass the request?
> Might this cause the backend to fail?
> I guess backend could try to recover by flushing the
> message queue, but if so, we probably should document this.
> And if not, why do we care about merged regions?

You are right, this is not working for the second part,
it was a misunderstanding from my side.

Now, for the first set_mem_table_call, Prerna is right,
the client having negotiated the reply_ack, we should wait for it.


I propose we drop patch 2, and only pick the first one.

Michael, ok for you?

Thanks,
Maxime