laptop-mode-tool not working in Arch Linux

Question

I've installed laptop-mode-tools and optional dependencies on Arch Linux. Then I've enabled laptop-mode.service and rebooted the system.

If I check if the service is actually working according to this (Para 3. Is Laptop Mode Enabled?) I get the following:

$ cat /proc/sys/vm/laptop_mode
0

The file /var/run/laptop-mode-enabled is not found. Finally systemctl tells me:

laptop-mode.service         loaded active exited    Laptop Mode Tools

All the above "symptoms" tell me that the laptop-mode service is not actually working.

What am I missing?

EDIT I have noticed that $ cat /proc/sys/vm/laptop_mode gives 0 even after doing thinks like in my answer below if I boot up on battery. Then if I connect the ac adapter for a few seconds and then disconnect it, $ cat /proc/sys/vm/laptop_mode will give 2. In any case now my battery seems to last much longer

Answer 1

Edit: I've switched to tlp (https://wiki.archlinux.org/index.php/TLP) which seems to work much better (at least in my experience) and works out of the box.

Old answer:

I think I found the solution: I have installed the following packages via yaourt:

$ pacman -S acpid bluez-utils wireless_tools cpupower

and then enabled the relevant services

$ systemctl enable acpid.service
$ systemctl enable cpupower.service
$ systemctl enable fancontrol
$ sensors-detect
$ systemctl enable lm_sensors.service

finally I have disabled/re-enabled laptop-mode.service (not sure it is actually needed):

$ systemctl disable laptop-mode.service
$ systemctl enable laptop-mode.service

and rebooted the system.

Now:

$ cat /proc/sys/vm/laptop_mode
2

that according to official documentation should confirm that service is actually running.

UPDATE

I have noticed that $ cat /proc/sys/vm/laptop_mode gives 0 if I boot up on battery with charge below 90%. Then if I connect the ac adapter for a few seconds and then disconnect it (or manually restart laptop-mode.service), $ cat /proc/sys/vm/laptop_mode will give 2. In any case now my battery seems to last much longer.