On Wed, Jul 15, 2020 at 02:29:04PM +0100, Alex Bennée wrote:
> Stefan Hajnoczi <stefanha@redhat.com> writes:
> > On Tue, Jul 14, 2020 at 10:43:36PM +0100, Alex Bennée wrote:
> >> Finally I'm curious if this is just a problem avoided by the s390
> >> channel approach? Does the use of messages over a channel just avoid the
> >> sort of bouncing back and forth that other hypervisors have to do when
> >> emulating a device?
> >
> > What does "bouncing back and forth" mean exactly?
> 
> Context switching between guest and hypervisor.

I have CCed Cornelia Huck, who can explain the lifecycle of an I/O
request on s390 channel I/O.

Stefan