On Thu, Jul 4, 2013 at 7:12 PM, Warren Block <wbl...@wonkity.com> wrote:
> Attached is a proposed patch for -head that adds a "hyper" mode to powerd.
> Instead of slewing like the adaptive modes, this mode drops all the way to
> the lowest frequency when the system is idle, and jumps all the way to the
> highest frequency when there is any load.
> Subjectively, it seems more responsive for desktop use than hiadaptive
> mode. That's hard to benchmark. Power usage is another question. This
> mode might use less power than the adaptive modes, but that's also
> difficult to benchmark.
> Comments welcome.
I have not looked at the patch yet, but it should really only use EST and
not TC or throttling as many systems, when throttled and put into deep
sleep modes (C3 or lower) will hang.
Studies have shown (sorry, but since I retired I have lost the papers on
the subject) that best power efficiency is when the system is operated at
minimum performance when idle and maximum when not, so this is probably a
good idea for most any non-mobile system and most mobile system
applications. There are cases when you may be willing to pay a response
price to keep the battery alive a little longer when performing ongoing
activities that don't need large amounts of CPU like listening to music.
As I have often pointed out, TCC and throttling were never intended for
power management and I strongly recommend that they be disabled. OTOH, deep
sleep states are huge winners and should be used to their maximum. EST is a
smaller win, but can make a system seem sluggish, especially when added to
TCC or throttling.
R. Kevin Oberman, Network Engineer
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