A real Pay Per Use billing feature

As a new user, I´m really excited with OpenNebula possibilities and I would like to suggest (or check if it is possible) to use Showback module in other way, not just charging for Provisioned resources but charge using a metered usage of resources (CPU/Memory/Disk). I guess that this will open a world of new possiblities.

We understand the motivation for this request, but besides CPU is not trivial to know the Memory and Disk consumption of a guestOS.