> > Isn't the point to deliver max perf with min energy?
>
> The point is that your window of user experience is 16/8ms. If the workload completes
> interactively to fill that "QoS" at the current frequency without going over a utilisation
> threshold in that sliding window, you *do not want to go any higher*.


Wouldn't you want to run at lower voltage/frequency if possible?

Generally the point is changing V/F should be inexpensive to enable using the optimal V/F combo.

> So your 120MHz FIVR is completely and utterly pointless. You would be wasting energy at higher
> voltages for no gain in user performance.

Shifting to low voltage fast seems valuable, right?

> Fmax should only every be reached and triggered after
> continuous load of 2-3x of user experience window - current mobile phones do that in around 40-50ms,
> anything faster than that is waste of energy and battery life. These are not HW limitations, but
> learning the hard way what the most efficient way to design battery powered DVFS logic.

Would that change if V/F switch took nanoseconds and cost little energy?

Seems like you would want to dynamically adjust voltage...even if at fixed frequency.

David