Enabling power management on Debian 5 ( 29 Nov 2011 )

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Enabling power management on Debian

Debian 5 supports CPU power management, but it is not installed by default, at least when using the most basic install (for example, for use as an NFS server).

Contents [hide] 1 Installation of CPU Power Management Components 2 Configuration of CPU Power Management Policy 3 Permanent Configuration 4 Power Management Values 5 See Also

Installation of CPU Power Management Components

apt-get install cpufrequtils sysfsutils

Configuration of CPU Power Management Policy

• Determine the CPU type,

cat /proc/cpuinfo | grep "model name"

• Enable the correct driver for the CPU type using modprobe (see table below), for example

modprobe p4_clockmod

• Select the desired power saving mode (the 'CPU Policy Governor', see table below), for example

modprobe cpufreq_conservative

• Determine the list of CPUs present (for example cpu0 and cpu1 might be reported),

dir /sys/devices/system/cpu

• Apply the policy to the CPU(s). Note that this must be applied to each cpu reported above,

echo conservative | tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo conservative | tee /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

• Confirm the configuration:

cpufreq-info

Permanent Configuration

• Apply the driver and power save mode to /etc/modules (see tables below for parameters),

echo p4_clockmod | tee -a /etc/modules
echo cpufreq_conservative | tee -a /etc/modules

• Enable the policy by editing /etc/sysfs.conf using nano. Add a line for each cpu reported using the desired policy per table above,

devices/system/cpu/cpu0/cpufreq/scaling_governor = conservative
devices/system/cpu/cpu1/cpufreq/scaling_governor = conservative

Power Management Values

CPU Type	Driver Name	modprobe example	/etc/modules example
AMD K6	powernow_k6	modprobe powernow_k6	echo powernow_k6 | tee -a /etc/modules
AMD K7	powernow_k7	modprobe powernow_k7	echo powernow_k7 | tee -a /etc/modules
AMD K8	powernow_k8	modprobe powernow_k8	echo powernow_k8 | tee -a /etc/modules
Generic Driver	acpi_cpufreq	modprobe acpi_cpufreq	echo acpi_cpufreq | tee -a /etc/modules
Pentium M	speedstep_centrino	modprobe speedstep_centrino	echo speedstep_centrino | tee -a /etc/modules
Pentium 4	p4_clockmod	modprobe p4_clockmod	echo powernow_k6 | tee -a /etc/modules

Policy Name	Description	modprobe
cpufreq_performance	Maintains the highest speed - no power saving	modprobe cpufreq_performance
cpufreq_powersave	Maintains the lowest speed - maximum power saving	modprobe cpufreq_powersave
cpufreq_ondemand	Dynamic adjustment, tailored for performance	modprobe cpufreq_ondemand
cpufreq_conservative	Dynamic adjustment, tailored for power saving	modprobe cpufreq_conservative

Policy Name	Permanent example	/etc/sysfs.conf
cpufreq_performance	echo cpufreq_performance | tee -a /etc/modules	devices/system/cpu/cpu0/cpufreq/scaling_governor = performance
cpufreq_powersave	echo cpufreq_powersave | tee -a /etc/modules	devices/system/cpu/cpu0/cpufreq/scaling_governor = powersave
cpufreq_ondemand	echo cpufreq_ondemand | tee -a /etc/modules	devices/system/cpu/cpu0/cpufreq/scaling_governor = ondemand
cpufreq_conservative	echo cpufreq_conservative | tee -a /etc/modules	devices/system/cpu/cpu0/cpufreq/scaling_governor = conservative

See Also

• Installing vmware tools on Debian 5
• Creating an NFS Server on Debian
• Debian

This page was last modified on 29 November 2011, at 13:37

http://blog.peacon.co.uk/wiki/Enabling_power_management_on_Debian