Battery saving tip

ikoz

Battery life is usually less than expected due to unoptimized software and processors clocking too high. On my devices, I set the CPU governor to 'powersave', which reduces power usage but also performance.
There are multiple scaling governor settings which might not be available on all devices (depends on kernel configuration)

performance : high frequency; slightly increased performance and battery consumption
powersave : low frequency; reduced performance and superior batter life
schedutil : changes according to the scheduler (default on my device)

This command list the available governors to set for each core (should be more than those I listed above)
sudo cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors
Report which governors are currently selected for each core:
sudo cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
Set the scaling governor to powersave to every core:
echo "powersave" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

The commands above do not need mounting root as read-write, any change is reverted on reboot.
I tried to make an app for configuring these (a while ago) but I had trouble with sudo.

Linus67

@ikoz
The commands still work. I still need to check how much money can be saved using them.
Good idea for an app

ikoz

@Linus67 Yes, these commands will always work on any Linux device since they rely on kernel APIs. Be aware of the noticeable performance impact, while powersave governor increases efficiency (performance per watt), it can increase latency on old devices.
About the app, I thought it would be better if it were part of a larger "power saver" app since a single app with 3 buttons that not only is unconfined but also needs root access seems unecessary.

Linus67

@ikoz
The scripts work perfectly, but I’ve had no luck with the desktop shortcut.

[Desktop Entry]
Name=Powersave ON
Exec=/home/phablet/powersave_on.sh
Terminal=false
Type=Application
Icon=/home/phablet/powersave_on.png

Anyway, let’s test how much power this actually saves.
On the Pixel 3a, I only notice a slight drop in performance.

ikoz

@Linus67 it needs to be ran as root. Sudo is interactive in terminal so it won't work, but pkexec is the GUI equivalent so it should launch a popup for the password. Alternatively set the suid bit of the script to make it always run as root without password (and ensure the file is not writable by phablet as that would allow local privilege escalation).