How to allocate virtual processor cores?

[arowe123]

Hello,

In the virtual machine settings, there is an option to set the number of process cores for the VM. Now assume I have a 4 core proc with HT, so 8 threads, can I set the vm to "have" 6 cores? Is there any actual benefit to doing so, and how are the host's resources actually allocated? Would the VM have effectively 6 threads on the host to work with?

Thanks

[wila]

Hi,

You could, but your performance would likely be worse as you are creating CPU scheduling issues between the VM and your host.

A good rule of thumb is to not give your VM more as half as what is available (and preferable one less virtual CPU)

So in your case I would stay under 4 cores for the guest.

--

Wil

[arowe123]

so if N = number of threads available on my processor, The rule of thumb is N/2 - 1. Or in my case, I should allocate three threads?

[wila]

Hi,

To be clear, it's a rule of thumb I use for hosted virtualisation products from VMware, such as Workstation and Fusion.

So yes, 3 virtual CPUs or even less.

There can always be exceptions, but if you want get good performance on all your VMs then the above is my recommendation.

It allows you to spin up multiple VMs of that configuration and even on moderate workloads it tends to work very well.

--

Wil