Pinning CPUs in OVM (Xen) and deploying multiple guests?

Fugazi1000

Due to some Oracle licence restrictions I am considering the use of Oracle VM Server.


Is it possible to have multiple guest OS instances use the same 'pinned' CPUs or Cores? i.e. can I manually overcommit a resource, or once I use a specific CPU and core for the 1st VM guest, I can no longer use it for another. Can anyone confirm?

This to apply to OVM v3.1

undomiel

I know in Xen you can pin multiple vcpus to the same cpu so I would make the assumption that you can in OVM. I have not used OVM though so I can't give you a definitive answer.

Fugazi1000

Thanks undomiel.

Can I ask the same question about ESX 5.1?

Is it possible to have a number of guests, have affinity to the same pCPU? If it is possible, then what is the maximum 'ratio'?


Perhaps I will pose it another way. I have a single socket, hex core host with hyperthreading disabled. So 6 cores.

I create 8 virtual machines, each with 2 vCPUs. I set affinity for each VM to 3 pCPUs (as per VMware recommendation).

So:

VM1 - pCPU 0,1,2
VM2 - pCPU 0,1,2
VM3 - pCPU 0,1,2
VM4 - pCPU 0,1,2
VM5 - pCPU 3,4,5
VM6 - pCPU 3,4,5
VM7 - pCPU 3,4,5
VM8 - pCPU 3,4,5

Ignoring the potential inefficiency and loss of features. Is this a valid configuration please?

undomiel

I've never run into any maximum pinned cpu limits. I would imagine that you could pin as many vCPUs to a single pCPU as you want, albeit you'll have to suffer with the performance issues of such a configuration.