XP Guest with 4 cores assigned?

[John_Leask]

I noticed in this post that it is possible to assign more than just two cores to a VM under workstation, though it is obviously not supported. I thought I'd give this a try to boost performance of a XP SP 3 guest, but I'm not having much luck.

The guest shows all 4 cores in the device manager, but only two show up as being utilized in the task manager. This fusion thread indicates that the problem is down to XP seeing the core as 4 seperate physical processors, when it only supports a max of 2 processors (though more cores as long a no more than 2 physical CPUs).

Am I simply out of luck with more cores in an XP guest? Is it time to upgrade the guest?

Am I likely to have stability issues using this unsupported tweak?

Thanks.

[AndreTheGiant · Accepted solution]

Have a look at this thread:

Andre

[John_Leask]

Very nice!

Thanks, that did the job perfectly - I now have the following in the .vmx file:

cpuid.supportsMulticore = "TRUE"

cpuid.coresPerSocket = "2"

numvcpus = "4"

Task Manager in the guest now shows all 4 cores, and they're all being utilized.

I guess it might make more sense for me to set the coresPerSocket to 4, so it looks like a single quad core cpu (the system has 2 quad core xeons) in case something gets confused seeing four X5560 cores looking like two dual core cpu's, but I'll hold off on that for now as it seems to be working fine.

Now I also need to figure out if it makes sense to have hyperthreading enabled - will both the guest and host perform better with the guest having 4 of the 8 real cores, rather than 4 hyperthreaded cores from the 16. Maybe something to try on a rainy day...