Ryzen 3600 -divide 6 cores / 12 threads

[mehargags]

Hello Everyone,
I got a Hetzner AX41 Ryzen 5 3600 Hexa-Core and want to host a few Windows KVM plus some Linux containers. Being new to the premise, I seek advise how I should divide the available 6 Cores / 12 Threads efficiently.

Between 2x Windows KVM -CPU set to "host" should I set 2 cores to each of them or can I set one of them to use 4 Cores ? I presume Cores inside Proxmox means "physical cores" and not the threads or else pls correct me.

Presuming 6 cores : I can divide 3+1+2 for Win1, Win2, LXD respectively
presuming threads, I can divide 4+4+4
please correct me if I get it wrong with threads

 

[t.lamprecht]

Hi,

Between 2x Windows KVM -CPU set to "host" should I set 2 cores to each of them or can I set one of them to use 4 Cores ? I presume Cores inside Proxmox means "physical cores" and not the threads or else pls correct me.

The CPU settings from the VM mean how many cores the VM will see, each of that core shows as thread on the host.

You cannot give on VM more cores (=threads) than the host can handle, KVM (the fast para-virtualization) cannot really handle that and it would not make sense, as there cannot run that many threads at the same time anyway.

But, the total core count of multiple VMs can be in sum bigger than available logical processors cores on your system.

I.e., you cannot have one VM with 13 cores, but you can have three VMs each having 12 cores.
They will then be scheduled fairly (or if you set CPU shares, then you can also give one VM more CPU time even if all have the same core count).

Most of the time the VMs do not need 100% of their cores all the time, so CPU "overcommitment" makes sense to do, it helps to use the resources of the hypervisor host more efficiently.
https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_cpu

Hope that helps a bit.

 

[mehargags]

Thanks... I understood most of it.
I will give it a go and ask back if other doubts come up.
Many thanks