Re: [virtio-dev] Re: [Qemu-devel] [PATCH] qemu: Introduce VIRTIO_NET_F_STANDBY feature bit to virtio_net

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 26 Jun 2018 20:50:20 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Tue, Jun 26, 2018 at 05:08:13PM +0200, Cornelia Huck wrote:
> > On Fri, 22 Jun 2018 17:05:04 -0700
> > Siwei Liu <loseweigh@gmail.com> wrote:
> >   
> > > On Fri, Jun 22, 2018 at 3:33 PM, Michael S. Tsirkin <mst@redhat.com> wrote:  
> > > > I suspect the diveregence will be lost on most users though
> > > > simply because they don't even care about vfio. They just
> > > > want things to go fast.    
> > > 
> > > Like Jason said, VF isn't faster than virtio-net in all cases. It
> > > depends on the workload and performance metrics: throughput, latency,
> > > or packet per second.  
> > 
> > So, will it be guest/admin-controllable then where the traffic flows
> > through? Just because we do have a vf available after negotiation of
> > the feature bit, it does not necessarily mean we want to use it? Do we
> > (the guest) even want to make it visible in that case?  
> 
> I think these ideas belong to what Alex Duyck wanted to do:
> some kind of advanced device that isn't tied to
> any network interfaces and allows workload and performance
> specific tuning.
> 
> Way out of scope for a simple failover, and more importantly,
> no one is looking at even enumerating the problems involved,
> much less solving them.

So, for simplicity's sake, we need to rely on the host admin
configuring the vm for its guest's intended use case. Sounds fair, but
probably needs a note somewhere.