> Questions about the roadmap for 3.0 and SMP?
>
> Can a domU be a larger SMP than the underlying host, e.g. can
> one make a 5-way domU on a 4-way host?
Yes.
> How do SMP domUs get scheduled? For example, if there are 2
> 2-way domUs running on a 2-way host, can both domUs be
> running simultaneously (1 CPU from each) or does each SMP
> domU get scheduled en mass, using both host CPUs when running
> at all times?
Both doms could end up getting run at the same time, particularly if one
VCPU in each is idle.
> What is the expected loss in performance of running a domU
> with identical SMP characteristics to its host? In other
> words, if running a single 4-way domU on a 4-way host, what
> would one expect the performance loss to be?
Depends how much dom0 is being invoked to do IO. It''s a real pain if
you''ve got a 4 way machine with an IO intensive 4-way guest and dom0
running device drivers: you have 5 balls to keep in the air and only 4
hands. You might be better off hot-unplugging one of the guest''s VCPUs.
[NB the situation is even worse on a 2-core box]
> Can an SMP domU migrate to a host with less cpus, more cpus?
Yes, they will be able to.
Ian
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