Beyond Linux® From Scratch (System V Edition) - Version r12.4-1328

Chapter 12. System Utilities

Power-profiles-daemon-0.30

Introduction to Power-profiles-daemon

The Power-profiles-daemon package provides a program that allows modification of the system power/behavior state. This is used on many laptops and can be used by a Desktop Environment to activate power saving or performance CPU governors through dbus. On other systems, Power-profiles-daemon can be used as a streamlined way to set the CPU governor in order to increase system performance at the cost of energy usage.

[Note]

Note

This version of BLFS may not build or run some packages properly if LFS or dependencies have been updated since the most recent stable version of the System V books.

Package Information

Power-profiles-daemon Dependencies

Required

Polkit-127, PyGObject-3.54.5 (pycairo is not needed), and UPower-1.91.1

Optional

GTK-Doc-1.35.1, The rest are for the tests, dbusmock-0.38.1, umockdev-0.19.4, isort, and mccabe

Kernel Configuration

Enable the following options in the kernel configuration and recompile the kernel if necessary: 

Power management and ACPI options --->
  CPU Frequency scaling --->
    -*-   CPU Frequency scaling                                       [CPU_FREQ]
    -*-     'performance' governor                    [CPU_FREQ_GOV_PERFORMANCE]
    <*/M>   'powersave' governor                        [CPU_FREQ_GOV_POWERSAVE]
    # Select if CPU is Intel:
    [ /*]   Intel P state control                             [X86_INTEL_PSTATE]
    # Select if CPU is AMD:
    [ /*]   AMD Processor P-State driver                        [X86_AMD_PSTATE]

Device Drivers --->
  # Some drivers under this submenu provide "platform profile" support
  # and power-profiles-daemon can take advantage from platform profiles;
  # select a driver if suitable for your platform:
  [ /*] X86 Platform Specific Device Drivers --->         [X86_PLATFORM_DEVICES]

Select the appropriate sub-options that appear when the above options are selected. As much as possible, the layout should be the same as in kernel configuration menus.

Installation of Power-profiles-daemon

Install Power-profiles-daemon by running the following commands: 

mkdir build &&
cd build &&

meson setup                        \
      --prefix=/usr                \
      --buildtype=release          \
      -D gtk_doc=false             \
      -D tests=false               \
      -D systemdsystemunitdir=/tmp \
      .. &&
ninja

If you have installed the external dependencies, to test the results issue: ninja test.

Now, as the root user: 

ninja install

Now, clean up an unneeded systemd unit installed into /tmp: 

rm -fv /tmp/power-profiles-daemon.service

Create a directory required for persistent power states after reboot: 

install -vdm755 /var/lib/power-profiles-daemon

Command Explanations

-D gtk_doc=false: Prevents building the documentation. Remove this if you have GTK-Doc installed and wish to build the documentation.

-D tests=false: Prevents building the tests because they cannot be run within the boundaries of BLFS. Remove this if you have installed the external dependencies and wish to run the tests.

-D systemdsystemunitdir=/tmp: Removes the dependency on systemd.

Configuring Power-profiles-daemon

Boot Script

To automatically start the power-profiles-daemon when the system is rebooted, install the /etc/rc.d/init.d/power-profiles-daemon bootscript from the blfs-bootscripts-20251220 as the root user: 

make install-power-profiles-daemon

Select a Power Profile

To list all supported power profiles, issue: 

powerprofilesctl

To activate a power profile (for example performance), issue: 

powerprofilesctl set performance

Some desktop environments (for example GNOME and KDE) also provide a graphical interface to interact with power-profiles-daemon and activate a power profile.

The activated power profile is automatically stored in /var/lib/power-profiles-daemon/state.ini and power-profiles-daemon will read it out and activate it again on the next boot if the bootscript is installed as above.

[Caution]

Caution

On some older systems power-profiles-daemon will appear to install and indicate correct values, but will not actually work. To check this, run cat /sys/devices/system/cpu/cpufreq/policy0/scaling_driver. If the result is not "intel_pstate" but instead "intel_cpufreq" (or similar on AMD systems), then power changes must be made manually.

To change power states manually, first check to see what governors are available with: cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_governors. Then set the desired governor as the root user with: 

gov=performance
for CPUFREQ in /sys/devices/system/cpu/cpufreq/policy*/scaling_governor; do
  echo -n ${gov} > ${CPUFREQ}
done

If you are setting the scaling_governor to "performance", be careful about heat and battery issues with extended use.

Contents

Installed Program: powerprofilesctl
Installed Libraries: None
Installed Directories: None

Short Descriptions

powerprofilesctl

This allows the user to set the power governor of the CPU.