Re: SMP and Xen

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Jan 02, 2007 at 10:52:43AM -0500, Steven M. Bellovin wrote:
> I have a dual-processor machine I'm using for Xen.  A few questions...
> 
> First -- is it safe to use SMP with Xen?  I've heard contradictory
> opinions on this.  This is Xen3.0.3 on 4.0beta2.

I have a server here with 2 hyperthreaded dual-core intel CPUs. Xen sees
8 CPUs, and runs fine

> 
> Second -- should my Dom0 see both CPUs?  Currently, it does not.

It will see all physical cpus (cpu0, cpu1, etc ...) but only one vcpu for
now.

> 
> Third -- is there any performance benefit to setting 'vcpus' to 2 (for
> a DomU that would benefit from that)?  That is, will a DomU actually
> run on more than one CPU?

A linux domU will (I have one with 8 vcpus on the abobe server), a NetBSD
domU won't for now. Adding SMP surport to NetBSD/Xen is on my todo list, but
it will take some time ...

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--