Bug 323817

Summary:	Opengl 3.1 setting gets lost after reboot
Product:	[Plasma] kwin	Reporter:	Felix Michel <felix_michel>
Component:	scene-opengl	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal
Priority:	NOR
Version First Reported In:	4.11.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Felix Michel 2013-08-21 06:12:44 UTC

When I set compositing to opengl 3.1 i have no tearing and kwin is fast and slick. when i reboot i have some tearing and kwin is little bit slower, still fast. the problem is the tearing when scrolling or watching a full screen flash video. it seems that after the reboot the settings are changed back to opengl 2.0. I have an nvidia graphics card.

Reproducible: Always

Steps to Reproduce:
1. Set compositing type to opengl 3.1, no tearing
2. Reboot
Actual Results:  
after reboot there is again tearing.

Expected Results:  
the compositing type opengl 3.1 should be activated also after reboot.

Comment 1 Felix Michel 2013-08-21 06:22:45 UTC

*** Bug 323818 has been marked as a duplicate of this bug. ***

Comment 2 Thomas Lübking 2013-08-21 09:42:02 UTC

This has nothing to do with the GL version (if actually reset that's either due to HW support or a different bug) but a problem to reliably detect the availability of triple buffering. see dupe.

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

Comment 3 Felix Michel 2013-08-21 09:48:53 UTC

well, what i dont get then why do i have a performance and a tearing difference? no tearing if i reset the opengl option, but the tearing is present again when i reboot.

Comment 4 Thomas Lübking 2013-08-21 14:49:37 UTC

(In reply to comment #3)
> well, what i dont get then why do i have a performance and a tearing
> difference?

Did you read across the dupe?
In a nutshell: triple buffering is (likely) misdetected during login. Without either it or usleep yielding, swapping causes high cpu load, so it's forcefully deactivated.

W/o triple buffering, also chances raise to drop or miss a frame (because we stay in event processing as long as possible) and the event processing time naturally shortens as well -> seems slower.

-> Ensure to activate triple buffering and override the detection.