powerd adaptive mode latching

Kevin Oberman oberman at es.net
Fri Jan 11 10:13:49 PST 2008

> Date: Fri, 11 Jan 2008 11:51:07 +0000
> From: "Igor Mozolevsky" <igor at hybrid-lab.co.uk>
> Sender: owner-freebsd-current at freebsd.org
> On 11/01/2008, Dag-Erling Smørgrav <des at des.no> wrote:
> > The whole point of powerd is to automatically adapt to the load.  If
> > your laptop "lags too much" powerd should detect that and increase the
> > CPU frequency.  However, poor interactive response can result when CPU
> > frequency fluctuates too quickly; perhaps your problem will go away with
> > Andrew's patch, which is intended to dampen such fluctuations?
> I was also thinking that the power increase probably shouldn't be
> linear, maybe there should be a choice of algs: 2-step, 50%-100%, etc.
> Normally you don't mind power dropping slowly, but for most things you
> don't want to wait N-seconds for the clock to be stepped up to its
> full throttle...

The part of powerd.c that controls this is very easy to understand and
modify. I write almost no C these days and I had no problems changing
the adaptive algorithm to try other things.

Try your idea and see how it works.
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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