KDE4 power consumption issues

[Lubos Lunak]

On Sunday 11 of November 2007, Sebastian Kuegler wrote:
> I've had a look at how KDE4 performs on laptops, using the powertop
> utility. KDE4 currently performs poorly WRT to the number of wakeups, the
> good news is that large parts can probably be blamed on knotify4 not
> playing nicely yet.
>
> Here are some more detailed results:
>
> Wakeups per second
>
> 		KDE3	KDE4 (composited)	KDE4 (no composite)
> ------------------------------------------------------------------------
> KNotify(4):	.4	887 (!)			955
> KWin		1	70			0
> Total:		41	1260 (!)		1108 (!)
>
> Time in C3	99.8%	82.9%			93.3%
...
> In my data, KDE4 wakes up the CPU less than without compositing, this is
> probably measurement errors. In other test runs, I've seen the number of
> wakeups go down when I disabled the composite features in kwin.
>
> The worst offender in KDE4 is obviously knotify. KWin composite doesn't
> play really nice either (on an idle desktop, it should sleep, no?)

 I think there are currently more important problems than [refresh rate] 
wakeups per second. Besides, if you run on battery and find this to be a 
problem, you don't want to use compositing at all anyway. And that's only 
wakeups BTW, there are no repaints when idle. Such minor things have to wait 
(but you can send a patch indeed).

-- 
Lubos Lunak
KDE developer
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