Proxmox use only 1 cpu for hypervisor

[spearox]

Hello!

How can i setup more CPU to use for Hypervisor? I set big iptables rules and under attack one core gose up to 100% and freeze but i have 16 core for this.

 

[wolfgang]

Hi,
if you focus the VM/CT then you can set the vcpus on the Hardware/Resources Tap.

 

[spearox]

No, I not mean the VM/CT i mean the hypervisor. Aka Xen Dom0 configured to 1 core default. The proxmox use only 1 core if i see properly and i want to add more core to hypervisor.

 

[LnxBil]

This is IMHO not possible directly. There is no clean separation like in XEN with KVM/LXC on Linux.

But Wolfgang is right: If you set e.g. all cpu's except the first to all VMs, then the first will always be free.

 

[wolfgang]

In KVM vcpus are processes.
This is an other model then Xen.

 

[spearox]

So i can't add more core? And maybe i can free up the core1 from the vms?

 

[wolfgang]

I think you get somthing wrong.
In KVM all vcpus (VM cores / CT cores) are processes.

So is you have 2 Socket and 8 real cores on one Socked with Intel HT.
It is total 32 cores to use.

If a VM has 1 Socket and 16 cores you are able to use 50% of the cpu power of the host.
If a VM has 2 Socket and 16 cores you are able to use 100% of the cpu power of the host.

 

[fabian]

So i can't add more core? And maybe i can free up the core1 from the vms?

the hypervisor is (lightly) using all cores, because VMs don't get exclusive access to cores, they run as processes. normally, the hypervisor should not run anything that uses a lot of resources (except for the VMs and CTs).

if something running on the host is using only 1 CPU, that means that application is single-threaded, which in general cannot be changed by a setting. but some applications make this configurable, and you can limit processes using cgroups. so first, you need to find out which process is using that 1 core, and then you can find out whether this is an artifical limitation that can be changed, or whether it is just how that program was written.