Running PowerTOP on boot on Void Linux
PowerTOP doesn't remember settings between restarts, so it needs to be executed on every boot. Here's how I did it on Void Linux with runit.
Runit executes every script in /etc/runit/core-services once on boot. So I created a /etc/runit/core-services/97-powertop.sh script:
msg "Powertop autotune..."
powertop --auto-tune
And made sure that it was executable with sudo chmod +x /etc/runit/core-services/97-powertop.sh.
Since PowerTOP's auto tune enables power management for every available device, my USB mouse kept turning off after 2 seconds of standby. In order to increase that delay to 10 minutes I changed the service file to this:
msg "Powertop autotune..."
echo $((10 * 60 * 1000)) > /sys/bus/usb/devices/1-1.6/power/autosuspend_delay_ms
powertop --auto-tune
The /sys/bus/.../autosuspend_delay_ms path will change depending on the device, so to discover it run sudo powertop and manually switch the flag in the Tunables tab.