virtualbox.org

There is the possibility of monitoring resource (OS: linux,windows) in VirtualBox [The percentage of usage CPU and RAM]?
EXAMPLE: Utilization at system startup...

There are already built-in system monitors for each OS. Do you suggest that VirtualBox implements something similar? For every OS that it runs?

Why?

See the manual, section 8.35, "Vboxmanage metrics". I used to use these for a heartbeat, early on in my office server virtualization project.

You have to "setup" the metrics monitors, then you can "query" the metrics info.