CPU Sockets vs. Cores/Socket

[mikeborschow]

I don't want to assume that I know what these are because I don't. These settings are in the KVM configuration section. What are they? What are good guidelines for setting them?

Thanks.

 

[dietmar]

I don't want to assume that I know what these are because I don't. These settings are in the KVM configuration section. What are they? What are good guidelines for setting them?

Thanks.

New KVM version can simulate Multi-core CPUs (Cores setting):

http://en.wikipedia.org/wiki/Multi-core_(computing)

A Socket is the place where you plug in the CPU.

So normaly you use:

cores: 1
socket: 1

which is also the default.

 

[mikeborschow]

If I wanted to assign "2 CPUs" to a virtual machine, what is the difference in performance between:

• 1 CPU socket and 2 Socket/Cores
  -vs-
• 2 CPU sockets and 1 Socket/Core

 

[dietmar]

If I wanted to assign "2 CPUs" to a virtual machine, what is the difference in performance between:

• 1 CPU socket and 2 Socket/Cores
  -vs-
• 2 CPU sockets and 1 Socket/Core

For some software licenses this can be a big difference.

Else it does not matter usually.

 

[mikeborschow]

So is it safe to assume that this is for immulation purposes and not related to actual hardware usage? Not to beat the subject to death, but let me ask this as well. Assuming the sofrware license is for one CPU and in the computer I have 2 quad core CPUs. Can I tell KVM 1 CPU Socket with 8 Socket/Cores?

 

[dietmar]

So is it safe to assume that this is for immulation purposes and not related to actual hardware usage?

yes - it simply starts "Socket*Cores" kvm threads.

Not to beat the subject to death, but let me ask this as well. Assuming the sofrware license is for one CPU and in the computer I have 2 quad core CPUs. Can I tell KVM 1 CPU Socket with 8 Socket/Cores?

yes, should work. (I guess you meant 1-Socket/8-Cores)