powermanagement plans for KDE4

Sebastian Kügler sebas at kde.org
Fri Aug 10 14:43:53 BST 2007

Hi there,

During aKademy in Glasgow, Danny Kukawka Kevin Ottens and I sat together and 
discussed how powermanagement in KDE4 should look like. My personal plans are 
to align Kubuntu closely with that so we can prevent duplicate efforts in the 
future. Also, current powermanager has some architectural issues, which will 
be resolved with those plans.

The minutes of this meeting have been sent to KDE's hardware-devel 
mailinglist, you can find it archived at 
http://lists.kde.org/?l=kde-hardware-devel&m=118374720211142&w=2. Please read 
it carefully as its vital for understanding the plans laid out in this email.

First off, the problems I see with current powermanager are:

- It's written using PyQt, which gives us a memory penalty of ~8MB and makes 
  it start relatively slow for such an applet
- Its design uses polling, so it updates slow and keeps the CPU awake more 
  than absolutely needed

All those problems are addressed with the solution we're aiming for for KDE4.
There is a basic port of powermanager to PyQt4 in svn trunk, but that does not 
address the first issues, the second issues can be solved, but haven't been 
tackled yet. I probably won't put time into this.

A draft implementation of the Powermanagement Plasma DataEngine and a 
reference implementation of a battery applet are in 
http://websvn.kde.org/trunk/playground/base/plasma/. I also blogged about it, 
read http://vizzzion.org/?blogentry=716. 
I'm not up to date of the current state of kpowersave, but Danny can probably 
give details about its current state.

Finally, I'm happy that we're making progress towards sharing resources and 
having the powermanagement mess on a promising route forward (the userspace 
parts, at least). If people want to contribute to this solution, that'd be 

Please speak up and attach patches if you have problems with this idea. :-)

 http://www.kde.org | http://vizZzion.org |  GPG Key ID: 9119 0EF9 
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