[one-users] Some questions about overcommitment in OpenNebula 4.2 using KVM

[Michał Madziar]

On 2013-10-16 14:42, Gerry O'Brien wrote:
> Hi,
>
>     Do you know if the CPU parameter has any effect on the amount of
> real cpu used, e.g. if I set the CPU parameter to 0.1 will this limit
> the actual cpu usage?

libvirt uses cgroups, so yes, it does.

>
>     Also, can the monitor driver be  configured to report multiples of
> memory and allow memory overcommitment in the same way?

Just assign whatever you want to $total_memory in kvm.rb, but keep in
mind that if ballooned/deduplicated pages will start to differ either
swap will be used (which will probably kill the host) or oomkiller will
kick in.

Example:
$total_cpu = 2000
$free_cpu = $total_cpu - $used_cpu
$total_memory = $total_memory.to_i+$free_memory.to_i
$free_memory = $total_memory - $used_memory.to_i
print_info("HYPERVISOR","kvm")
#...

Dashboard charts will look strange but it seems to work.