RE: Unable to use multiple CPUs inside an HVM

"David Levinger" <davidl@xxxxxxxxxxxxxxxxxxx> · Mon, 21 Apr 2008 16:05:40 -0700 (PDT)

Title: Unable to use multiple CPUs inside an HVM

You were 100% correct Andrew.  The problem
was with how I configured XP, though I seriously thought I knew better.  I
sysprepped my image and redid it with the “multi-processor” hal and voila I now
see and utilize both cores.  The odd part, however, is that the time required
to complete a processor intensive operation seems to remain almost the same. 
Instead of using 50% of the available host CPU it now using 100% but estimates
only a tem minute savings in processing time… Whaaaaat?

I still feel like I’m missing something
rather important, but at least both CPUs are now available for use.

d

From: Andrew Cathrow
[mailto:acathrow@xxxxxxxxxx] 

Sent: Sunday, April 20, 2008 11:12
AM

To: David Levinger

Cc: fedora-xen@xxxxxxxxxx

Subject: Re:  Unable
to use multiple CPUs inside an HVM

When Windows installed selects the HAL library appropriate the the
hardware. If you install on a single CPU system then the uniprocessor HAL is
installed.

If you then add a second vcpu to the guest then the windows HAL won't see it. 

You'll need to replace Window's hal. See links below for some background. I
don't think there is a Microsoft *supported* way to do this but I've done this
a number of times without issue on XP and 2000, but I've not tried this on
2003, 2008 or Vista

http://support.microsoft.com/kb/309283/en-us

http://support.microsoft.com/default.aspx?scid=kb;EN-US;237556

On Sat, 2008-04-19 at 10:40 -0700, David Levinger wrote:

Hey Guys,

I have a
fully virtualized XP guest that is set to have 2 VCPUs and in the guest I see 2
CPUs but when it is under heavy load it only utilizes 1 of the physical cores.

Both xm and
virsh show that the guest only has 1 CPU, but my config file and the guest show
it should have 2.

What am I
missing? How can I get this guest to have access to both cores?

Thanks!

David

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