cpuunits option: no effects (nor evidence

[esteco]

Hello people,
i cannot find any difference in VM performance (wether it be a KVM or an OVZ container) when I change the cpuunit value in its configuration.

I can set it successfully (vzctl set 205 --cpuunits 100000 --save) and I can read the new value both from the VM option tab in the web gui and from the vm conf file in the ssh terminal. But when I test the VM performance (phoronix test suite) i see no difference between tests with different cpuunit values.

Morover, if I "ps -ef" on the host, I see no evidence of the parameter in the running vms processes.
Any hint? what's wrong with my setup? How can I red from the console the current value?
Thank you

 

[dietmar]

cpuunits is a relative value, so it only makes sense if you run more than one VM/CT.

 

[esteco]

Thank you for your reply.

Where can I find some hints on properly configuring a VM for max performance on the host?
The PVE host is a a 8 core AMD Opteron 4130 @2.6GHz, 128 Gb ram, OS on 15Krpm SAS Raid disks.
I am runnng 3 VMs, 2KVM and one OpenVZ container. All share the same specs: dual cpu with 4Gb RAM, RAW vdisk on local storage. What changes between VMs is cpu configuration and options (as asked above).

OS is Ubuntu 14, the benchmarking suite is phoronix-test-suite, results are similar between KVMs, noticeably worse on OpenVZ. My reference is a an old 16 core Intel Xeon X5550 @2.67GHz server, 24GB RAM that run circles arount the AMD (around twice the AMD CPU performance).

Thanks again

 

[spirit]

also, cpuunit is not enabled with qemu if a virtio device is defined.