On Fri, Mar 19, 2010 at 12:42:02PM +0100, Jiri Denemark wrote:
> > > +/**
> > > + * virDomainMigrateSetMaxDowntime:
> > > + * @domain: a domain object
> > > + * @downtime: maximum tolerable downtime for live migration, in
nanoseconds
> > > + * @flags: fine-tuning flags, currently unused, use 0
> >
> > We discussed that previously, obviously the nanosecond accuracy is
> > not expected but most uses of durations in the API now use nanoseconds
> > and after all it's better to have something too fine grained than
> > too coarse there
>
> The virDomainJobInfo API is measuring in milliseconds actally. I'm not aware
> of any API using nanoseconds, so I think ms is fine for migrate downtime
Right, there's no other API taking nanoseconds. On the other hand I didn't
want to limit capabilities of hypervisors as, e.g., qemu supports nanoseconds
precision (although it won't be able fulfil that for sure). Milliseconds seem
to be enough these days and we can always add a flag requesting higher
precision in the future if it's required.
QEMU may support it, but there's no way migration of any active guests will
ever complete in < 1 ms, so nanosecond resolution is definitely overkill !
Daniel
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