Xen / NetBSD CPU configs (performance)

["Niels Dettenbach" <nd%syndicat.com@localhost>]

Dear netbsd users,

hope this is not to off-topic here (same question goes to Xen project lists):

Currently i run different NetBSD DomUs on a Xen Dom0 which is located on a 2x 
Quad-Core XEON (Intel). The DomUs have access up to 4 CPU cores (mainly 
shared), while the DomU sees this only one (virtual) CPU. 

The DomUs acting as different internet servers (whith more or less load) - this 
means many / most of the running applications are able to participate from a 
SMP / MP environment (i.e. Apache, Streaming Servers, Mailservers...).

Is this DomUs CPU configuration (4->1) optimal from a performance view?

Or: Will NetBSD DomUs acting better when they get more then a single (virtual) 
CPU or should i let Xen / Dom0 do the CPU sheduling? 

Do you have experiences about the optimum cpu/vcpu setup or ratio (i.e. 4->1 or 
4->2)?

Many thanks for any hint.
Cheers,

Niels.
---
Niels Dettenbach
http://www.syndicat.com