Linux CPU scaling helper

This tool lets you switch performance preferences on Linux for CPUs with cpufreq driver (no need for cpufreq-utils). Features:

• Get current modes for CPU cores
• Set new mode for all cores
• Enable/disable "extreme powersave mode" (that is, force the lowest possible frequency for all cores)

Usage, simplest case

The simplest way to use this script is just download it and run as root (see examples).

wget https://raw.githubusercontent.com/kolayne/linux-cpu-scaling-helper/master/cpu.sh
chmod +x cpu.sh
sudo cpu.sh get

That's it! 🎉

Run as non-root

To let (some) users other than root run the script, perform the following initial setup (as root):

1. Create a group for users allowed to run the script: groupadd cpu_tuners

2. Add user(s) to the group: usermod -aG cpu_tuners $USER

3. Create a systemd service to set appropriate permissions on system files:

   • Copy the service file: cp update_sysfs_cpu_permissions.service /etc/systemd/system/

   • Run systemctl enable --now update_sysfs_cpu_permissions.service to set permissions this time, and enable the service to run on every boot (needed because permissions of virtual files do not survive shutdown/reboot).

Run automatically on charger connect/disconnect events

It might also be convenient to run the script on laptop charger connect/disconnect events (via udev). For that:

1. If you have several partitions, put the script on the root partition for it to run when udev discovers the charging hardware. For example, cp ./cpu.sh /usr/local/bin/cpu.

2. Put the path to your script to the 99-cpu_energy_preference_on_charger.rules file.

3. Put the rules file to the rules directory: cp 99-cpu_energy_preference_on_charger.rules /etc/udev/rules.d/

Examples

Manual running examples:

./cpu.sh get          # View current preferences
./cpu.sh list         # List valid options for `set` (for the first core)
./cpu.sh set default  # Set a mode for all cores
./cpu.sh extreme      # Enter extreme powersave mode (force lowest possible frequency)
./cpu.sh unextreme    # Exit extreme powersave mode