Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Put the power modes in a list to make them easier to find.

Reviewed by: joel
MFC after: 1 week

Add -m and -M options to control the minimum and maximum frequency.

PR: bin/145063
Submitted by: Boris Kochergin <spawk at acm.poly.edu>
Reviewed by: cperciva
Approved by: rrs (mentor)
MFC after: 2 weeks

then -> than

MFC after: 1 day

Grammar and minor tweaks to powerd(8) man page.

PR: docs/133186
Approved by: ed (mentor)
MFC after: 2 weeks

Fix a typo higter->higher.

Spotted by: ganbold

Set of powerd enchancements:

1. Make it more SMP polite. Previous version uses average CPU load that
often leads to load underestimation. It make powerd with default
configuration unusable on systems with more then 2 CPUs. I propose to use
summary load instead of average one. IMO this is the best we can do without
specially tuned scheduler. Also as soon as measuring total load on SMP
systems is more useful then total idle, I have switched to it.

2. Make powerd's operation independent from number and size of frequency
levels. I have added internal frequency counter which translated into real
frequencies only on a last stage and only as good as gone. Some systems may
have only several power levels, while others - many of them, so adaptation
time with previous approach was completely different.

3. As part of previous I have changed adaptive mode to rise frequency on
demand up to 2 times and fall on 1/8 per time internal.

4. For desktop (AC-powered) systems I have added one more mode - "hiadaptive".
It rises frequency twice faster, drops it 4 times slower, prefers twice
lower CPU load and has additional delay before leaving the highest frequency
after the period of maximum load. This mode was specially made to improve
interactivity of the systems where operation capabilities are more
significant then power consumption, but keeping maximum frequency all the
time is not needed.

5. I have reduced default polling interval from 1/2 to 1/4 of second.
It is not so important for algorithm math now, but gives better system
interactivity.

Discussed on: mobile@

Add an abbreviation for adaptive mode, and document all the abreviations.

s/5.5/6.0/ in HISTORY section.

Discussed with: ru

-mdoc sweep.

Be more consistent with the rest of the manual page.

Accept "maximum" and "minimum" modes as well as their abbreviations.

MFC after: 2 weeks

Add '-P' option which allows to specify pidfile.

Fixed markup.

Approved by: re

Drop the default running value to 60% from 80%. Testing shows that we
cycle too much, wasting power if we trigger a jump to full speed too
easily. CPU-bound tasks quickly push idle below this level.

man page -> manual page

Change the default levels for adaptive mode to 80% and 90%. On a system
with moderate IO going on, system usage can hover around 65-77% even
though it would benefit from higher performance. Typically, only truly
idle systems pass the 90% mark so only demote then.

Import powerd(8), a utility for managing power consumption. Currently, it
just uses cpufreq(4) but in the future it should also do things like spin
down disks. This is based on the work by Colin Percival (called "estctrl").