Re: [virtio-dev] [PATCH] snd: Add virtio sound device specification

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> > In general if I have guest core affinity then hypervisor context
> > switching for that guest is in low 10s of uS (depends on hypervisor
> > of course and HW). This is good enough for low latency audio.

> That's why we are really curious how other people target such issues
> with audio virtualization. And that's why I'm not sure about the spec
> in this regard. We could say something like "you can activate
> zero-copy mode, but it's up to your HW, OS and luck", but it does not
> sound very nicely.

real-time stuff in virtual machines is tricky, and real-time audio isn't
special here.  I don't think there is a need to discuss that in the
device specification.

The part which is important for the virtual hardware is to design the it
in a way that the number of context switches (system calls, vmexits) is
minimized.

cheers,
  Gerd