Software-based energy savings

Conclusions

Tweaking the right controls lets users fight power hogs on laptops and desktops. Some tips are fairly easy to implement, but for others, you will need to delve more deeply into your system settings. In all cases, the reward for your work will be vastly improved battery life on notebooks and power savings in the long run.

Laptop Mode Tools

Configuration file: /etc/laptop-mode/laptop-mode.conf

Activity monitor: /proc/sys/vm/laptop-mode (1 = aktiv)

The Laptop Mode Tools are disabled by default on Ubuntu. To enable, change the value false in the ENABLE_LAPTOP_MODE=false line of the /etc/default/acpi-support file to true. The Powersave daemon provides functionality similar to the Laptop Mode tools on openSUSE.

Glossar

DPMS

Display Power Management Signaling is a method of using the graphics card to trigger monitor power state changes with three energy-saving states: Standby, Suspend, and Power off. Both devices need to support this approach.

C States

Sleep or idle states for ACPI-capable processors. Five levels range from C0 to C4. The higher the number, the less power the CPU uses.

The Author

Karsten Reich studied history and computer science at the Technical University of Dresden, Germany. He's been interested in computers since he was a child, and got started with Linux on Debian 3.0 (Woody).

He covers software, with the occasional hardware test as a Contributing Editor for our sister publications EasyLinux and LinuxUser.

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