[SOLVED] 2 nodes, 1 showing CPU Core amount wrong

[proxmoxusergwm]

Hello guys,

just a quick question.

We have 2 servers/nodes in our environment, with 2 CPUs/sockets each.

One server has 2xCPUs with 14 cores each (total of 28 cores), and the other server has 2xCPUs with 18 cores each (total of 36 cores).

Now the question:
In the node overview, Proxmox is showing the server with the total 36 cores correct ("36 CPUs"), but it is showing the server wit the total 28 cores wrong (it says "56 CPUs"). We couldn't figure out why.

Can we change it? If yes, how?
Does it matter?
Should we then take that into account when allocating CPUs to our VMs on that server (allocating CPUs as if we had 56 CPUs)?

Best regards and thanks in advance guys!

 

[B.Otto]

That sounds like HyperThreading is not activated on one node. The count in 'CPU(s)' is the availiable Threads. For example, in our servers we have two Xeon Silver 4212 (12 Cores / 24 Threads each). Proxmox then shows

CPU(s) - 48 x Intel(R) Xeon(R) Silver 4214 CPU @ 2.20GHz (2 Sockets)

Please note that you dont have to 1:1 map vCPUs to Threads. Each core used by a VM is handled as one Thread in the underlying Linux Thread Scheduler, and the Scheduler takes care of balancing the actual load over its availiable threads.
There has also been a discussion about it a few days ago: https://forum.proxmox.com/threads/sockets-vs-cores-vs-threads-vs-vcpu-vs-cpu-units.110868/

 

[proxmoxusergwm]

Thanks for the fast reply, Benedikt!!

I will check out our HyperThreading settings.

Update Jul 06, 2022: Yes, it actually is our HyperThreading settings not being enabled on one node. Thanks again!