CPU Type Model - VM

[Tdreissi]

Hello,

I have a server with an Intel Xeon Icelake CPU and now I want to configure the VMs according to the CPU.
As far as I understand and have read, it increases the performance and you can also use the CPU features.
Default kvmx64 is very limited.

See image


But I get errors when I start a VM for the first time.
kvm: warning: host doesn't support requested feature: MSR(10AH).taa-no [8-bit]
I read that you probably need a conf file.
/etc/pve/virtual-guest/cpu-models.conf
But I don't really understand the flags and options.

Can someone help me - thanks....

 

[MarkusF]

For the best performance choose the CPU type 'host'. This will set all flags according to your CPU.


"If you want an exact match, you can set the CPU type to host in which case the VM will have exactly the same CPU flags as your host system.

This has a downside though. If you want to do a live migration of VMs between different hosts, your VM might end up on a new system with a different CPU type or a different microcode version.If the CPU flags passed to the guest are missing, the QEMU process will stop. To remedy this QEMU has also its own virtual CPU types, that Proxmox VE uses by default."

https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_cpu_type

 

[Tdreissi]

Hi Markus,

thanks for the answer.

When setting up my clusters, I always make sure that they are all identical in terms of CPU & RAM.

And "host" is enough to be able to use all CPU features?
Why are there special settings for the CPU codename, when "host" is enough?

Bye....

 

[dhcolesj]

It's there for a few reasons I can think of but In the end it's about options and flexibility that's there for your liking.
You can choose to prioritize Performance or Flexibility in hardware purchases, or level out between them.
That's what draws me into Open Source the most. I get to choose, not some corporate knuckle head who thinks I should be forced to send him screen shots of my desktop every few seconds or minutes.

 

[BobhWasatch]

Why are there special settings for the CPU codename, when "host" is enough?

In case your cluster hosts aren't identical. You can choose a lowest common denominator.