How do I activate Powertop only when my laptop is running on the battery?

Question

I don't want powertop to reduce performance while my laptop is plugged in.

Answer 1

Use acpi_listen

Terminal -> acpi_listen

Example : Unplug your power supply and you will see something like this ...

ac_adapter ACPI0003:00 00000080 00000000 <--- Important
processor LNXCPU:00 00000081 00000000
processor LNXCPU:01 00000081 00000000
processor LNXCPU:02 00000081 00000000
processor LNXCPU:03 00000081 00000000
battery PNP0C0A:00 00000080 00000001

Under /etc/acpi/events create a file :

sudo nano /etc/acpi/events/switch-to-battery.sh

event=ac_adapter ACPI0003:00 00000080 00000000
action=powertop --auto-tune

Make ist executable:

chmod u+x /etc/acpi/events/switch-to-battery.sh