Extend laptop battery life with CPU scaling

If you have a laptop with poor battery life, it is really annoying to have it run out when you're doing something important like word processing. Many computers support CPU scaling however, which is a way of making your processor use less power.

(Note that this post might look a bit intense, but it really isn't, it just has a few terminal commands)

The first step of this is to see what modes your CPU can use, so type

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

in a terminal. You should see a range of options, if not your CPU may not support scaling. My options are: "conservative ondemand userspace powersave performance".

At this point you should check the default for your CPU with:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

this will tell you which mode your computer is currently using so you can switch back to it later.

You can then tell your computer to use a certain mode on the CPU. If you're just taking notes at work you probably need no more than powersave (or your CPU's equivalent).

cpufreq-selector -c 0 -g powersave

Note that you must put your core number after the -c. If your CPU has a dual-core processor (2 cores), run this twice with "-c 0" and "-c 1" (and do the appropriate for triple/quad cores).

And that's it! You can check how your CPU is doing with

cat /proc/cpuinfo | grep "cpu MHz"

Try comparing it with performance mode to see the difference.