Xen SMP DomU status (from cherry-xenmp)

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

Hello,
I've done some tests with the code from the cherry-xenmp branch.
After fixing some interrupt issues I could reenable using HYPERVISOR_block()
in the idle loop, so that domUs are not spinning when idle any more.

I've tested a i386 XEN3PAE_DOMU and amd64 XEN3_DOMU kernel.
Both could complete a build.sh -j12 release on a 8-CPU system, with
xen 4.1.1 and a NetBSD 5.1_STABLE dom0.
The i386 XEN3PAE_DOMU performances are good. It will eventually trigger
a bug in the hypervisor, I need to see if xen 4.1.2 is better in this
area.
The amd64 performances are not so good. Lots of time is spent in the
kernel and there's a hunge number of IPIs. I suspect this is related
to the APDP use in amd64, it may be possible to improve this.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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