Bug 324049

Summary:	Screen tearing after upgrade to KDE 4.11, nVidia propriatery driver, no tearing with KDE 4.10.4
Product:	[Plasma] kwin	Reporter:	svenssonsven8
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	major	CC:	lucidlytwisted, sancho-p, thebenj88
Priority:	NOR
Version:	4.11.0
Target Milestone:	---
Platform:	Kubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description svenssonsven8 2013-08-26 07:13:55 UTC

I run Kubuntu 12.10 with Kubuntu Backports PPA enabled. After I upgraded to KDE 4.11 from this PPA, I started noticing significant screen tearing while moving open windows for instance. I didn't had any tearing problems in 4.10.4.
After I boot to desktop, for a few seconds there is no tearing and then it suddenly starts and never goes away. I found the following workaround though:

System settings > Desktop effects > Advanced and set the compositing type to opengl 3.1 > Apply> back to opengl 2.0> Apply to make the tearing go away. However, as soon I reboot, the tearing is back and I have to redo the whole procedure again.

It is as though the settings are not sticking after a reboot.

Reproducible: Always

Steps to Reproduce:
1. Boot to desktop, immediately open a window (dolphin instance will do)
2. Move the window around, there is no tearing
3. After a few seconds, suddenly, the tearing appears
4. Go to System settings > Desktop effects > Advanced and set the compositing type to opengl 3.1 > Apply> back to opengl 2.0> Apply
5. No tearing for the remainder of desktop session
6. Reboot
7. The tearing is back in the same way as in steps 2-3
Actual Results:  
The tearing is clearly visible after few seconds on every boot to desktop

Expected Results:  
No tearing should appear, as was the case in KDE 4.10.4

nVidia 260 GTX
Propriatery nVidia driver 310.XX (will have to look up the exact version)
The same driver was in use before upgrade with no tearing.
KDE 4.11.0

Comment 1 Thomas Lübking 2013-08-26 07:23:46 UTC


*** This bug has been marked as a duplicate of bug 322060 ***

Comment 2 svenssonsven8 2013-08-26 07:41:14 UTC

Hi Thomas,

thank you for pointing me to the correct bug report, which I unfortunately couldn't find on my own before reporting this one. I apologize for that.

Reading the comments there, I am unable to determine whether there is a workaround and when/if we can expect a patch that will fix the issue.

Can we hope for a fix in next version of 4.11?

Thank you in advance Thomas.

Comment 3 svenssonsven8 2013-08-26 07:50:53 UTC

Hi Thomas,

thank you for pointing me to the correct bug report, which I unfortunately couldn't find on my own before reporting this one. I apologize for that.

Reading the comments there, I am unable to determine whether there is a workaround and when/if we can expect a patch that will fix the issue.

Can we hope for a fix in next version of 4.11?

Thank you in advance Thomas.

Comment 4 Thomas Lübking 2013-08-26 09:05:14 UTC

override triple buffer detection:
export KWIN_TRIPLE_BUFFER=1

if you don't have triple buffering enabled and don't intend to, force the nvidia blob to use usleep yielding
export __GL_YIELD="USLEEP"

you can auto-export them for the session in ~/.kde/env scripts

we'll probably defer triple buffering detectin a bit for the next point release - no idea why it doesn't work duriNg startup for too many ppl

Comment 5 svenssonsven8 2013-08-26 10:06:12 UTC

Thank you for your fast reply.

I will try your suggestions when I get home tonight.

Glad to hear that it is a known issue and is being worked on.

Thanks once again Thomas.

Kind Regards,
Veroslav

Comment 6 Ben R 2013-09-16 09:06:33 UTC

Hi, I'd like to add that Thomas' triple buffer override worked for me. I'm currently using KDE 4.11 & the proprietary nvidia drivers (325.15). Hope that helps.

Comment 7 Aleksandru 2014-01-06 15:45:17 UTC

Bug appeared with the version of KDE 4.11.0
Not depends on the version of the nvidia drivers.

Comment 8 Thomas Lübking 2014-01-06 17:41:55 UTC

vsync didn't actually work in pre-4.11 versions at all (see bug #307965) and if neither triple buffering or usleep yielding is present, you drop back into *exactly* that code.

check bug #322060 and the attached script on how to either activate triple buffering, convince KWin that its available (cannot be queried) or export USLEEP yielding to enter vsync'd always swapping path.