A new update to Power Profiles Daemon in Ubuntu 24.04 brings about improved power efficiency for laptop users, especially those using modern AMD devices.
The update notes for the power-profiles-daemon package in Ubuntu 24.04 share that it’s now “battery-state aware”, leading some drivers to use a more power efficient state when the balanced profile is on battery.
Power profiles daemon may be a low-level process, but it presides over the Power Mode settings available in the Quick Settings menu. The settings include “balanced” (the default setting), “power saver”, and, when supported by certain drivers, “performance”. This recent update modifies the “balanced” setting.
If you have Intel or AMD hardware that can use P-State drivers (generally, these are Skylake and Zen 2 upwards), the “balanced” profile is now linked to a new balance_power Energy Performance Preference (EPP) profile instead of the balance_performance one.
When a power cable is connected to the laptop, the “balanced” mode transitions to the balance_performance profile behind the scenes. This implies that Ubuntu now possesses four power modes, albeit only three are visibly accessible in the GUI.
This update also raises the energy_perf_bias to 8 for Intel, which is a rise from 6.
As larger numbers indicate greater power efficiency, Intel users might—though I am not promising anything—experience enhanced power savings in Ubuntu 24.04 compared to preceding versions. The extent of this is influenced by other ongoing processes, device configuration, other settings, and many more factors.
P-state drivers offer more detailed, adaptable, and specific power and processor frequency scaling controls than acpi-cpufreq. However, the latter is still extensively employed in Linux distros due to its comprehensive hardware support and reliable functionality.
Want to know which power driver Ubuntu is using on your device? Open a Terminal window and run the following command (it doesn’t change anything, don’t worry):
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver
If able, the command prints the power governor/scaling driver in use (for each core), e.g, intel_pstate, amd_pstate, oracpi-cpufreq.
Other changes in power-profiles-daemon 0.21 include a crop of code optimisations, a flurry of fixes for the powerprofilesctl command-line tool, improved documentation, and autocompletion for both bash and ZSH (if install path provided for the latter).
Finally, the systemd service lockdown settings are said to now be “restricted even more”, which is reassuring (assuming you, unlike I, know what that means).
In all, a nice set of improvements and yet more reason to upgrade to Ubuntu 24.04 when it’s released (hopefully) on April 25, 2024.
Thanks Mario