Re: [PATCH v2 4/4] virtio-net: Add support for USO features

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

On Wed, Jul 31, 2024 at 08:04:24AM +0100, Daniel P. Berrangé wrote:
> On Tue, Jul 30, 2024 at 05:32:48PM -0400, Michael S. Tsirkin wrote:
> > On Tue, Jul 30, 2024 at 04:03:53PM -0400, Peter Xu wrote:
> > > On Tue, Jul 30, 2024 at 03:22:50PM -0400, Michael S. Tsirkin wrote:
> > > > This is not what we did historically. Why should we start now?
> > > 
> > > It's a matter of whether we still want migration to randomly fail, like
> > > what this patch does.
> > > 
> > > Or any better suggestions?  I'm definitely open to that.
> > > 
> > > Thanks,
> > > 
> > > -- 
> > > Peter Xu
> > 
> > Randomly is an overstatement. You need to switch between kernels
> > where this feature differs. We did it with a ton of features
> > in the past, donnu why we single out USO now.
> 
> This has been a problem with a ton of features in the past. We've
> ignored the problem, but that doesn't make it the right solution
> 
> With regards,
> Daniel

Pushing it to domain xml does not really help,
migration will still fail unexpectedly (after wasting
a ton of resources copying memory, and getting
a downtime bump, I might add).

The right solution is to have a tool that can query
backends, and that given the results from all of the cluster,
generate a set of parameters that will ensure migration works.
Kind of like qemu-img, but for migration.


-- 
MST