Hi,
I'm not sure if I understsnd the concept...
Isn't it a question of demand and supply.
You say..
which will measure how much voltage/power is needed at a given time
My understanding is different.
I see it like a diesel engine and an electric crane. The diesel engine does not need to know beforehand how much stones the crane has to lift.
The stones create a demand of power ... and the job of the diesel engine is to deliver this power. No need to measure, no need for a special crane motor, no need for communication, no need fo intelligence.
The diesel engine just needs to keep frequency and voltage constsnt.
The same is true for the power supply of a processor. It needs to keep the voltage constant...but the processor draws the current that then results in power.
For sure you may put in some intelligence ... but this usually is software controlled.
An example:
When you don't move the mouse of a PC for a longer time, then the software detects this, and may switch OFF your monitor.
Klaus