Hi,

I have the same type of concern :

• I've developped a piece of software, using C language libvirt APIs, running on RHEL KVM host. It collects a lot of metrics counters from the KVM Hypervisor.
• May I use it on a host part of an OpenStack infra ?

Thanks for help.

J.P. Ribeauville

Are you sure that instances that do not consume CPU at the time you are watching are useless ?

(hint, hint: this is a multifaceted question)

I.e. your question is a valid one, but that is probably the wrong question to ask.

EDIT: But if the user set this VM up for a service that consume very little CPU but which is critical for him ?

You should have a look at over-subscription, so that you can launch more instances than you actually have physical resources in your compute node(s), if you have a lot of this kind of instances running.

in /etc/nova/nova.conf:

cpu_allocation_ratio
disk_allocation_ratio
ram_allocation_ratio

Take a look on virsh cpu-stats. It does not give percentage, but still can be useful.