CPU cores limits for small builds

[axrusar]

Hi guys.
This must be a pretty newbie question, please do not shoot me

I am setting up a home Proxmox server for my nextcloud and a few very light usage VMs.
I have a regular desktop with an Intel I7-6700. 4 cores/8 threads. No server motherboard or xeon/epyc.
So basically there are 8 available CPUs, and i would like to understand how the VE manages them when setting up virtual machines.

So if i have 8 cpus available.. that means i will run out of cores setting up 4 VMs with 2 CPUs each? (assuming they are running all at the same time), or i can keep
setting up more VMs, and Proxmox is able to assign CPU resources to whatever VM needs power at the moment?
Do i actually need to leave a CPU alone available for proxmox itself to run?

My confusion is coming from looking for example at cloud computing providers, they usually have the options Dedicated CPU vs shared,
so i am wondering if Proxmox can share the same CPUs among all the VMs, (assuming they are not loaded 100% of course), or once you fire a VM, the CPUs are exclusively
locked to that specific VM and not available anymore to the rest of the server?

Excuse my broken English.. im not a native EN speaker.

Thank you guys!!!

 

[Dunuin]

A VM is just a KVM process and Proxmox VE will hypervise those processes cross all your CPU threads. So wouldn't be a problem to have for example 16 vCPUs across all your VMs even if you got only 4 physical cores. Of cause only as long as those vCPUs are idleing most of the time. A 4 cores 8 threads CPU might be able to handle 500% CPU time. So all vCPUs together only got 500% of CPU time to work with. So 5x vCPU at 100% utilization or 10x vCPUs at 50% or 20x vCPUs at 25% and so on.
But don't assign your VMs more vCPUs then needed or otherwise it will get slow because the process queue is building up.