How to configure cpudynd

NOTE!

See the Dynamic Frequency Scaling HOWTO on how to avoid using cpu frequency scaling daemons by using the kernel builtin ondemand governor.

In Debian, all you have to do is:

# apt-get install cpudyn

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

If you decide not to use the ACPI throttling functionality (as you certainly will on simple SpeedStep models like all T2x), cpudynd will work by exchanging the scaling governor: it will load the powersave governor by default and exchange it by the performance governor if the CPU load exceeds a certain level. Therefore, you have to make sure that those two governors can be used by the kernel, i.e. their modules (cpufreq_performance and cpufreq_powersave) are loaded properly.

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

# Cpudyn configure options

################################################
# COMMON OPTIONS
################################################
#
# Internal between idle ratio tests in 1/10 sec increments
#
INTERVAL=1

################################################
# CPUFREQ OPTIONS
################################################
#
# CPU idle work ratio to speed up
#
CPU_UP=0.5

#
# CPU idle work ratio to speed down
#
CPU_DOWN=0.9

#
# when using cputhrottling, what state to switch when speeding down
#
THROTTLING_LOW=7

################################################
# DISK OPTIONS
# (disabled by default)
################################################
#
# Timeout to put the disk in standby mode if there was no
# io during that period (in seconds)
#
#TIMEOUT=120

#
# Specified disks to spindown (comma separated devices)
#
# DISKS=/dev/hda,/dev/hdb

################################################
# EXTRA OPTIONS
################################################

# Available options are
# -acpi disables cpufreq and force the use of acpi
# -asus enables asus_acpi in some laptops
# -nice count also nice CPU usage as load as well
# -minf value Set the minimum CPU frequency in a value between 0.0 and 1.0
#
# EXTRA_OPTIONS=""