Bug 155694 - kwin causes many wakeups in compositing mode
Summary: kwin causes many wakeups in compositing mode
Alias: None
Product: kwin
Classification: Plasma
Component: compositing (show other bugs)
Version: unspecified
Platform: Ubuntu Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
Depends on:
Reported: 2008-01-13 23:42 UTC by Yves Glodt
Modified: 2008-10-11 10:20 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:


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Description Yves Glodt 2008-01-13 23:42:53 UTC
Version:            (using KDE KDE 4.0.0)
Installed from:    Ubuntu Packages
OS:                Linux


first, my congratulations for the great 4.0 release of KDE. I like it. You guys rock!

On my system (kubuntu feisty, intel driver, GM945 chipset) kwin causes around 65 wakeups/sec even while the system is idle, when run in compositing mode.

When I turn compositing off, powertop does not even list kwin anymore.

After reading http://bugs.kde.org/show_bug.cgi?id=152829 I tried using plastique instead of oxygen, but it does not make a change here, so I filed this under kwin.
Comment 1 Yves Glodt 2008-01-14 11:24:10 UTC
It should not matter, but I run gutsy and not feisty of course. Sorry for the mistake.

Btw, I tried today on another desktop-PC with onboard intel G915 graphics, and I see also around 65 wakeups. Without compositing again, kwin does not even appear in the list of processes in powertop.
Comment 2 Lubos Lunak 2008-01-14 23:07:16 UTC
The compositing repaint timer. Not really that important since compositing itself is not exactly resource-friendly.
Comment 3 Yves Glodt 2008-04-14 15:13:59 UTC
Out of curiosity... :-)

Would it be possible for kwin-compositing to be event based, instead of having a static timer? I guess kwin knows whenever an application paints something, and it could update the offscreen pixmap just in that case...?

Sorry in case I misunderstand the whole thing.

Apart of that, my respect to you Lubos for your work. Kwin compositing is really nice and makes using KDE even a better experience.
Comment 4 Raúl 2008-06-01 23:44:02 UTC
Any advance in this field?

Comment 5 James Horey 2008-06-09 00:22:46 UTC
This still occurs with KDE 4.1 Beta. Incidentally, Compiz wakes up between 11 - 20 times per second.
Comment 6 Yves Glodt 2008-06-09 08:54:22 UTC
On Ubuntu Hardy I measured even less than 10 wakeups for compiz, I remember around 6. But this probably depends on the amount of effects/plugins loaded.
Comment 7 Γιώργος Κυλάφας (Giorgos Kylafas) 2008-08-30 13:31:19 UTC
Judging by the commit message, the change in http://websvn.kde.org/?view=rev&revision=850941 by Lubos may have fixed this.
Comment 8 Lubos Lunak 2008-08-30 17:29:16 UTC
No, now :). r854913
Comment 9 Γιώργος Κυλάφας (Giorgos Kylafas) 2008-08-30 19:57:59 UTC
Thanks, this is great news!
I see the commit is against trunk, i.e. future 4.2.x. Any chance this fix will make it to 4.1.x, as well?
Comment 10 Yves Glodt 2008-08-31 03:11:32 UTC
Thank you Lubos, you definitely rock!
Comment 11 Lubos Lunak 2008-09-10 22:00:18 UTC
#9: Probably not. The fix can make whole compositing non-functional if there is a problem and needs more testing.
Comment 12 Yves Glodt 2008-10-11 10:20:08 UTC
I just dist-upgraded my aside-install of kubuntu intrepid, which, being based on kde 4.1, seems to have some compositing features backported from 4.2 trunk... :-)

There is cube, one can choose the window-switching effect, and ... wakeups of kwin are down to ~2 :-)))

I want to thank the kwin team for their great work!