Re: [Xen-users] Re: Windows and Multiple CPUS?

["Nemeth, Tamas" <nice@xxxxxxxxxxxxxxx>]

Hi,

I've tried to run w2k3 server with multiple CPUs, but i had to realize
that a HVM virtualized w2k3 has some timing (clock) issues. Timing
becomes somehow imprecise. I tried it on 64bit hypervisor and 32bit
dom0, xen version 3.2.1. I tried to ping a host from a multiple VCPU
windows and the packets coming back seemed to arrive earlier then they
left the NIC, or something like this. Can you confirm this symtom?
(However it's possible, this is a problem of networking, not timing.)
This problem doesn't exist on single VCPU Windows HVM domUs.

Cheers

Tamas


2008. 09. 19, pÃntek keltezÃssel 14.46-kor Andrew Lyon ezt Ãrta:
> On Fri, Sep 19, 2008 at 2:39 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
> > Hi,
> >
> > Am I correct in thinking that when Xen is running on a multi-core /
> > smp system and several cpus are assigned to a VM they are "presented"
> > as multiple single core cpus rather than 1 or more multi-core cpus?
> >
> > Microsoft CPU limits are for physical sockets, not cores.
> >
> > Windows XP and Vista are limited to two physical cpus, running under
> > Xen the maximum cpus I have seen in task manager and system properties
> > is 2, although device manager shows all of the assigned cpus (up to
> > 8).
> >
> > Windows 2003 and 2008 standard edition are limited to 4 cpus, which is
> > the limit I find under Xen, again device manager shows all assigned
> > cpus (up to 8).
> >
> > Is there any way to make windows see the cpus as multi-core so that
> > all 8 cores can be used ?
> >
> > Andy
> >
> 
> I've also noticed that if I run "xm list" repeatedly as the VM is
> starting up I can actually see the cpus being initialized, the value
> matches the limit i find in windows:
> 
> A Windows 2003 R2 Standard Edition 32 Bit VM:
> 
> #grep vcpu Win2003x86.cfg
> vcpus=8
> 
> xm list (several times during boot process)
> 
> Win2003x86                                  24  2048     1
> Win2003x86                                  24  2048     2
> Win2003x86                                  24  2048     3
> Win2003x86                                  24  2048     4
> 
> But if i booted this version of windows on the raw hardware all 8 cpus
> would be utilized.
> 
> Andy
> 
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