Re: [Xen-devel] credit1 scheduler question.

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Tue, Feb 7, 2012 at 8:12 PM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
> Hey George,
>
> I was wondering if you could explain in simple terms how the scheduler would
> handle per-physical CPU when there are say 16 guests (each guest is using
> one VCPU), 32 physical CPUs and dom0 is not restricted to any CPUs. Would
> the scheduler per physical CPU schedule: guest, dom0, guest, dom0, and so
> on; or would it be more random? (I assume that both guest and dom0 would do
> a hypercall yield too).

The scheduling would be random.  As far as I know, none of the
schedulers (sedf, credit1, or credit2) treat domain 0 differently from
any other domain.  Even guests which are very busy end up blocking
quite a bit, so the total runtime ends up being fairly random anyway.
Also, the dom0 vcpus are not pinned unless you specify dom0_pin_vcpus
on the xen command-line; so by default they will migrate freely around
the various cores.

Does that answer your question?

 -George

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