On Fri, Aug 26, 2016 at 11:40:48AM -0700, Steve Muckle wrote:

A policy of going to fmax on any RT activity will be detrimental
for power on many platforms. Often RT accounts for only a small amount
of CPU activity so sending the CPU frequency to fmax is overkill. Worse
still, some platforms may not be able to even complete the CPU frequency
change before the RT activity has already completed.

Cpufreq governors have not treated RT activity this way in the past so
it is not part of the expected semantics of the RT scheduling class. The
DL class offers guarantees about task completion and could be used for
this purpose.

Not entirely true. People have simply disabled cpufreq because of this.

Yes, RR/FIFO are a pain, but they should still be deterministic, and
variable cpufreq destroys that.

I realize that the fmax thing is annoying, but I'm not seeing how rt_avg
is much better.