Bug 386333

Summary:	Heavy stuttering with KWin and triple buffering
Product:	[Plasma] kwin	Reporter:	Steffen Coenen <tardingens>
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	hensoko, tardingens
Priority:	NOR
Version First Reported In:	5.11.2
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Steffen Coenen 2017-10-29 19:52:19 UTC

Using triple buffering leads to stuttering of window contents while KWin effects remain smooth. The stutter can be observed both on my desktop using the NVIDIA blob and on my Ivy Bridge laptop using the free Intel driver. If I recall correctly, I observed similar issues on an AMD card but I can not test this anymore since I do not have the card anymore. Forcing double buffering with KWIN_TRIPLE_BUFFER=0 seems to fix the problems. Another workaround is to set MaxFPS and RefreshRate to 70. The problem affects both OpenGL with GLX and OpenGL ES using EGL.

Steps to reproduce:
1. Start kwin_x11 with KWIN_TRIPLE_BUFFER=1
2. Start glxgears
3. Stutter should be visible

In comparison, KWin shouldn't stutter when used with KWIN_TRIPLE_BUFFER=0

This website can be pretty useful to test for stuttering too:
https://www.testufo.com/stutter#demo=smooth&foreground=ffffff&background=000000&pps=720

There are multiple other bug reports which might describe the same issue:
https://bugs.kde.org/show_bug.cgi?id=381444
https://bugs.kde.org/show_bug.cgi?id=353038
https://bugs.kde.org/show_bug.cgi?id=344433
https://bugs.kde.org/show_bug.cgi?id=351700

Comment 1 Martin Flöser 2017-10-29 20:15:19 UTC

Please provide output of 
qdbus org.kde.KWin /KWin supportInformation

When the problem is visible.

Comment 2 Steffen Coenen 2017-10-29 20:31:48 UTC

https://paste.fedoraproject.org/paste/cZ9C9rGxJPsw0lHd6MtKYw/raw
qdbus org.kde.KWin /KWin supportInformation

Comment 3 Hendrik Sokolowski 2017-10-29 20:48:38 UTC

Got the same problem with an i5-3320M using internal graphics and official intel drivers (Fedora 26 with linux 4.13.9).

drivers:
cairo.i686 					 1.15.4-25.intel20171
cairo.x86_64 					 1.15.4-25.intel20171
cairo-gobject.i686 				 1.15.4-25.intel20171
cairo-gobject.x86_64 				 1.15.4-25.intel20171
intel-gpu-tools.x86_64 				 1:1.18-25.intel20171
intel-graphics-update-tool.x86_64 		 2.0.5-25.intel20171
intellinuxgraphics-repo.noarch 			 2.0.5-25.intel20171
libva-intel-driver.x86_64 			 1.8.0-25.intel20171
xorg-x11-drv-intel.x86_64 			 2.99.917-28.20160929.fc26

kwin-startup:
OpenGL vendor string:                   Intel Open Source Technology Center
OpenGL renderer string:                 Mesa DRI Intel(R) Ivybridge Mobile 
OpenGL version string:                  4.2 (Core Profile) Mesa 17.2.2
OpenGL shading language version string: 4.20
Driver:                                 Intel
GPU class:                              IvyBridge
OpenGL version:                         4.2
GLSL version:                           4.20
Mesa version:                           17.2.2
Linux kernel version:                   4.13.9
Requires strict binding:                yes
GLSL shaders:                           yes
Texture NPOT support:                   yes
Virtual Machine:                        no

qdbus org.kde.KWin /KWin supportInformation:
https://paste.fedoraproject.org/paste/kZtjEemRGVlc4PEkozVbMw/raw

Comment 4 Martin Flöser 2017-10-30 06:43:43 UTC


*** This bug has been marked as a duplicate of bug 344433 ***