RFC: powerd algorithms enhancements

[Sam Leffler]

The biggest problem I see with powerd is that when a system is running 
with a reduced clock frequency interrupts are not processed at full 
clock speed.  This, for example, breaks the ath driver which can 
generate interrupts very quickly when  h/w MIB counters overflow in a 
noisy environment.  Because processing happens at the reduced frequency 
until powerd gets to run it causes livelock (or perhaps powerd does not 
raise the clock frequency because it's only accounting for user code--I 
haven't looked).

There's been talk about temporarily boosting the clock frequency in the 
kernel when processing interrupts.

    Sam