vSphere 5 multicore vs multi virtual socket

Zaits

Hello Everyone,

vSphere 5 now allows you to configure the number of virtual sockets vs number of cores per socket, but I see very little documentation on the benefit of doing one vs the other besides licensing restrictions. I understand the whole concept of the old ways and how 1 core = 1vCPU which means server 2003 can only have 4 cores etc, but what I'm looking for is someone can explain the benefit from a CPU scheduling point of view. Does the hypervisor care if I assign 1 virtual socket and 4 cores vs 4 virtual sockets and 1 core? Will I gain a performance increase or decrease by doing one method verses another? Does this only matter for applications that can benefit from multiple threads?

If someone could shed some light on this topic I think that would be a real benefit to the community.

Thanks,

Zaits

MentholMoose

As far as I know it is only for Windows licensing. I have not heard of any performance considerations when choosing the number of cores per socket.

jibbajabba

A vCPU maps to a core of the physical CPU anyway - so performance wise it doesn't make a difference. It is indeed mainly for licensing purposes.

While this article is for vSphere 4 and how to do this manually, the explanation still applies

VMware KB: Setting the number of cores per CPU in a virtual machine