[pve-devel] KVM with same cores as host is as slow as one core

[Stefan Priebe - Profihost AG]

Hi,

while benchmarking my kvm machines using unixbench i see the following
reproducable behaviour.

Host has 24 cores.

KVM Machine set to 2 cores: Unixbench Value 2514
KVM Machine set to 16 cores: Unixbench Value 6714
KVM Machine set to 24 cores: Unixbench Value 1742

Also i see a max of 105% CPU Usage of the KVM process when setting the
cores to 24.

While i'm seeing more than 1000% setting it to 16 cores.

Stefan