Yesterday I updated to KDE 4.11. I noticed huge horrid video tearing in KWin (more horrid than before).
After a while, I looked at the settings of KWin in systemsettings and saw there was a new composition type, "OpenGL 3.1". Wonderful, after years, the tearing went off! (or so it seems)
Then I rebooted. Tearing came back. Less than before, but it was there and it was pretty noticeable, specially when moving in Firefox with cursor keys. I did set KWin back to OpenGL 2.0 and then to OpenGL 3.1, and the tearing went off again.
I also noticed if I change from OpenGL 3.1 to OpenGL 2.0 it works too. It seems that I need to change the OpenGL version on every session. It does not matter which version I choose, but I have to change it in order to get rid of video tearing.
See bug #322060
There was a problem detecting triple buffering during startup, but that should be fixed.
Please ensure that triple buffering is enabled at all (/var/log/Xorg.0.log)
If it's not, please either enable it or export the yielding strategy.
If it is and you're sure to have 4.11.2, please run "kdebugdialog --fullmode", enable kwin (1212) and redirect the debug messages into some file (so we can see the output on triple buffering determination)
If it is *not* on nvidia, please attach the output of "qdbus org.kde.kwin /KWin supportInformation"
I added the TripleBuffer option and then it worked fine without tricks. Thanks :D
I read in the ArchLinux wiki TripleBuffer is enabled by default. Maybe it is not true?
Not for the nvidia blob:
(vsync != triple buffering)
You should however not be able to "trick" the system into (expensive) syncing.
Can you try disabling triple buffering again, re-login (ie. cause tearing), alter compositing ("fix" tearing), wait a minute (500 repaints to be more precise - move a window around, alt+tab or activate present windows or something. On constant 60fps repaints 500 frames =~ 8.3 secs) and dump the output of
qdbus org.kde.kwin /KWin supportInformation
thanks in advance ;-)
*** This bug has been marked as a duplicate of bug 322060 ***
Here it is. http://pastebin.kde.org/pii9bktfs
Painting blocks for vertical retrace: no
Something wrong here.
Should I do something with it?
No, but that smells like a bug and i wanted to record it here (pastebin will delete the post at some point)
Ok, I'm setting TripleBuffer on again then. I don't want to manually change composition type on every session.
Yes of course, sorry.
I just wanted to see the state in this condition (i maybe should have hinted that ;-)