SUMMARY After setting VRR policy to "Always" (or going fullscreen on "Automatic"), running Chromium with the Ozone hint property set to Wayland or auto, the browser fails to VSync unless the hardware cursor is moved (software cursor has no influence). STEPS TO REPRODUCE 1. Set VRR policy to "Always" or "Automatic" 2. Launch Chromium with the Wayland backend (and go fullscreen if VRR policy is set to "Automatic") OBSERVED RESULT The browser has a seemingly random frametime (easily observed with UFOTest, simply scrolling a website, or with a YouTube video), but while moving the mouse everything looks good - I get 165 FPS. (This isn't good for low framerate video playback though, as moving the mouse sets the refresh rate back to 165Hz.) EXPECTED RESULT Chromium's draw/swap calls should dictate the refresh rate in a stable manner. SOFTWARE/OS VERSIONS Linux: Arch Linux, kernel version 6.6.7-zen1-1-zen KDE Plasma Version: 5.91.0 (Plasma 6.0 Beta 2) KDE Frameworks Version: 5.247.0 Qt Version: 6.7.0beta1 ADDITIONAL INFORMATION Setting KWIN_FORCE_SW_CURSOR to 1 doesn't cause Chromium to sync properly while moving the mouse - could this have something to do with cursor plane separation?
This is almost certainly a chromium bug. It abuses presentation time to schedule its rendering, which does not work with VRR.
Can you report it upstream, Fililip?
Done https://bugs.chromium.org/p/chromium/issues/detail?id=1517884
*** Bug 480436 has been marked as a duplicate of this bug. ***