I am going to let the project team respond to the detail questions,
but I will respond to questions reguarding the "bigger picture".
>
> This seems specific to "idle" notification. Would it be useful to have
> something that dealt with other kinds of CPU state transitions as well?
> (C-states, for example?)
>
> -- Garrett
Predominantly, the issue to external devices is only idle, so that
they can take other actions to reduce power. Part of the assumption
here is that idle can absorb the extra latency required by the
callback and will reduce the impact to performance. Considering that
C/T/P-states will likely occur very frequently, having additional
notifications could circumvent the value of those state transitions.
Evolution of PAD (Power Aware Dispatcher) may change some of these
considerations, but for now this is the most we want to open the door.
---- Randy
