vcpu to cpu ratio

[dplsdev]

Hello,

I would like to know if (and how) there's a way on proxmox to assign a different percentage of real cpu for the virtual machine's cores.
Example: 1 CPU core VPS equal to 80% of real core.

Thanks

 

[leesteken]

Example: 1 CPU core VPS equal to 80% of real core.

You can set the CPU Limit (under Advanced options) to 0.8 times the number of VCPUs (which is by default the Cores times the Sockets), but this is an overall limit (not per core).
See the manual for more detailed information: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_cpu

 

[dplsdev]

You can set the CPU Limit (under Advanced options) to 0.8 times the number of VCPUs (which is by default the Cores times the Sockets), but this is an overall limit (not per core).
See the manual for more detailed information: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_cpu

CPU Limit to 0.8 means that if the user has 2 cores, he can use 80% of those, correct?

 

[leesteken]

CPU Limit to 0.8 means that if the user has 2 cores, he can use 80% of those, correct?

Not exactly; it could also be 100% of one core and 60% of another core. It's an overall limit, not per core.

 

[dplsdev]

Thanks, I read the guide and understood. I got one last question.
Does it apply after I reboot the vm or immediately?

 

[leesteken]

Does it apply after I reboot the vm or immediately?

I looks like it's applied immediately since the VM configuration is changed immediately instead of marked as changed. That's really easy to test yourself. In my test the limit kicked in immediately on a VM with a constant load. For a VM with 2 cores set the CPU Limit to 1.6.