Comment 603 for bug 59695

The laptop-mode-tools webpage says:

"
3. Is Laptop Mode Enabled?
How do I check if laptop mode is enabled?

Execute cat /proc/sys/vm/laptop_mode. If it contains a nonzero value, then laptop mode is enabled, if it says 0, then it isn't.
What's /var/run/laptop-mode-enabled got to do with things?

Well, this file is created and destroyed by the laptop-mode init script to enable/disable laptop mode activity. If this file is not present, then laptop mode tools will not do a thing except disable itself, even when you unplug your computer from the mains.
And what about /etc/default/laptop-mode?

That's only supported for backward compatibility with the old Ubuntu laptop-mode package. It contains a setting using which you can enable or disable laptop mode entirely.
"
[http://samwel.tk/laptop_mode/faq]

But you probably have already seen it, I guess.