KDE4 power consumption issues

[Hamish Rodda]

On Mon, 12 Nov 2007 02:49:27 am 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%
>
> (lower numbers == better, except for the C3 time, where higher percentage
> is better) The tests have been run with a fully-loaded KDE desktop, some
> applications open (konqi, kwrite, konsole, mostly). The results are not
> 100% accurate, but should give a fairly good idea of how we perform
> currently.
>
> 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?) Konsole,
> kwrite and konqueror are also not totally quite yet, they're performing a
> bit worse than their KDE3 counterparts, not sure why.

FYI, I've noticed during a debugging session of kdevelop that 
KAcceleratorManager has a timer which goes off very frequently.  Don't know 
if that's new though.  I would have thought this timer could be removed and 
an event filter installed instead, but I haven't looked into it.

Cheers,
Hamish.
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