One of my special interests is power management (PM).
While discussing if a display powermanagement option really should be in guidance‘s displayconfig, I had a look where
PM-related options are living in kcontrol at the moment.
It was quite a shocking experience.
Assuming I want to optimize my laptop for battery lifetime, where are the places I have to go in
kcontrol, what assumption do I have to understand? Let’s have a look.
- display power management comes to my mind, go to Peripherals -> Display -> Power
Control - Most WiFi card drivers offer a powe saving mode, go to Internet & Network ->
Wireless Network - Power Control -> Laptop Battery offers actions for events when battery is
running out and also some ACPI controls which make suspend modes and CPU power saving modes
available – if setup correctly, also there’s a battery monitor - My installation also has modules for IBM Thinkpad laptops (mostly for buttons / ACPI
events) and a Sony VAIO module which aims to make the battery status of two batteries available (I
have neither of those models, so these modules are of no use for me.)
I think the most easy thing for the novice user with respect to getting the laptop draining less
power is getting hopelessly lost.
The solution to this problem, however, is not trivial. Power management is related to a lot of
different areas, suspend modes such as suspend-to-ram, suspend-to-disk, power management of
different devices such as wireless adapters and the display play a role, but there’s obviously more
to it. I encountered that when designing the display powermanagement tab for guidance’s
displayconfig. It seems related to a screensaver (although a screensaver is no more than some eye
candy toy on more recent hardware), but DPMS is some sort of extreme screensaver. Then there’s CPU
states (C1 through C4 on some systems, although that’s really nothing the user should ever
notice).
The big question is: How can power management be handled in a sensible way?
That is without having duplicate configuration options.
The approach I’ve taken now in guidance
is offering a DPMS tab, mostly for practical reasons, with a button to configure the screensaver
which just starts the screensaver configuration module. I’m not sure if we’re going to keep it this
way, though.
If you’re also interested in this area, please drop me an e-mail at sebas@kde.nl. Maybe this
topic can also have profit by some discussion at aKademy
2005, which I’m going to attend.