https://bugs.kde.org/show_bug.cgi?id=527116
--- Comment #4 from Harald Weissmueller <[email protected]> --- Did some more experiments and found out that the stuttering problem is gone when switching to "prefer color accuracy" in the display configuration settings. The stutter only happens with "prefer efficiency". I also tried out environment variables that looked interesting but nothing there changed the problem besides "KWIN_DRM_NO_AMS=1". I tried "KWIN_FORCE_SW_CURSOR=1" and "KWIN_DRM_OVERRIDE_SAFETY_MARGIN=2000" and ...=3000. So the problem is happening in this combination: * fullscreen window on the left monitor, not the right monitor * "prefer efficiency" setting enabled for color * KWIN_DRM_NO_DIRECT_SCANOUT=1 The monitors are 4K resolution at 144 Hz and are both the same model and different ICC profiles for each. The two ICC color profiles I'm using were created by DisplayCal and have no calibration curves and have "XYZ LUT + matrix" for the profiling part of the file. But I also tried color profiles "none" and that also has the stuttering issue. Also, a mistake I made earlier: I thought that the "showcompositing" effect suppresses the problem but that's not correct, only the "showfps" and "showpaint" effects suppress the stuttering. The stutter also looks a bit suspicious with regards to the fps, it looks like it's stuttering at 72 fps or 48 fps or 36 fps according to what the vsynctester.com website javascript is seeing in Firefox and that's 144 Hz / 2 or 3 or 4. I could see 72 Hz on the refresh rate overlay that's built into the monitor when VRR is enabled. Just now I also noticed that direct scanout doesn't seem to activate for a fullscreen window on the right monitor, only on the left monitor. Maybe that's somehow related to why the stuttering issue is only on the left monitor. When a fullscreen window is covering the screen, I notice that the showcompositing effect is drawing an outline for where the Plasma panel is on my right monitor but not my left monitor. I have panels on both monitors. -- You are receiving this mail because: You are watching all bug changes.
