cpufreq and schedulers instead of powerd

[Eric Kjeldergaard]

Hello all.  I hope this is the right place for such an item.

I've been pondering processor dynamic clocking for a while and
recently have been wondering if it is optimal to have the processor
rate chosen by a daemon as it is now, or rather integrate the
downclocking into the scheduler.  My reasoning largely is based on the
thought of overhead for switching processor speeds.  With modernish
processors (especially the Pentium-m) it seems that the time to change
operating frequencies is very low which would lead me to think that
something like a scheduler could take advantage of that and clock them
down faster and more often.  Also, schedulers (I've been looking
mainly at ULE) have more knowledge about processor usage than just the
current load which appears to be all that powerd looks at.  Does
anyone have any additional information on dynamic clock handling in OS
schedulers or information on why freebsd chose powerd over an
implementation in scheduler(s)?

Eric Kjeldergaard

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