How to configure cpufreqd

In Debian, all you have to do is:

apt-get install cpufreqd

And in most cases it will work out of the box.

This is the default Debian config, but works well out of the box:

# this is a comment
#
# you need: 1 [General] section,
#           1 or more [Profile] sections
#                1 or more [Rule] sections
#
# a section ends at the first blank line
#
# [Rule] sample:
#           [Rule]
#           name=sample_rule
#           ac=on                    # (on/off)
#           battery_interval=0-10
#           cpu_interval=30-60
#           programs=xine,mplayer
#           profile=sample_profile
#
# [Profile] sample:
#           [Profile]
#           name=sample_profile
#           minfreq=10%
#           maxfreq=100%
#           policy=performance
#
# see CPUFREQD.CONF(5) manpage for a complete reference

[General]
pidfile=/var/run/cpufreqd.pid
poll_interval=2
pm_type=acpi #(acpi, apm or pmu)
# Uncomment the following line to enable ACPI workaround (see cpufreqd.conf(5)) # acpi_workaround=1
verbosity=4 #(if you want a minimal logging set to 5)

[Profile]
name=hi_boost
minfreq=66%
maxfreq=100%
policy=performance

[Profile]
name=medium_boost
minfreq=33%
maxfreq=66%
policy=performance

[Profile]
name=lo_boost
minfreq=0%
maxfreq=33%
policy=performance

[Profile]
name=lo_power
minfreq=0%
maxfreq=33%
policy=powersave

# conservative mode when not AC
[Rule]
name=conservative
ac=off                   # (on/off)
battery_interval=0-100
cpu_interval=0-40
cpu_nice_scale=1.5
delay_cycles=3
profile=lo_boost

# need some power
[Rule]
name=lo_cpu_boost
ac=off                   # (on/off)
battery_interval=0-100
cpu_interval=30-80
profile=medium_boost

# need big power (not if battery very low)
[Rule]
name=hi_cpu_boost
ac=off                   # (on/off)
battery_interval=50-100
cpu_interval=70-100
profile=medium_boost

# full power when AC
[Rule]
name=AC_on
ac=on                   # (on/off)
profile=hi_boost

# full power when watching DVDs and not AC:
# this is the last rule and takes less
# precedence with respect to the others
[Rule]
name=dvd_watching
ac=off                   # (on/off)
battery_interval=0-100
programs=xine,totem,vlc,avidemux
cpu_interval=0-100
profile=hi_boost

See How_to_make_use_of_Dynamic_Frequency_Scaling on how to avoid using cpu frequency scaling daemons.