Events needed to determine specific overheads

[andre-merzky]

For some unit states, part of the time a unit spends in that state can be considered overhead, and other parts not. For example, the time a unit spends in the scheduler waiting for a free core is not overhead, as that time would be spend waiting even in the ideal (theoretical) case -- but the time from when a core becomes available to when the unit leaves the scheduler with that core assigned, that time is implementation overhead.

To measure those times, RA needs to expose certain profiling events, and needs to enable the user to correlate those events to state transition events of specific units.

Specifically, we need two events supported right now

• the time a core becomes available (see above)
• the time a unit was spawned (== control handed over to the system)