https://bugs.kde.org/show_bug.cgi?id=527749
[email protected] changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |[email protected] --- Comment #1 from [email protected] --- I can reproduce this with a different trigger: KWin software brightness instead of Night Color. Night Color is disabled on my system. SETUP - CachyOS, kernel 7.3.0-5-cachyos - KDE Plasma 6.8.1, KWin 6.8.1, KDE Frameworks 6.31.0, Qt 6.12.0, Wayland session - AMD Radeon RX 9070 XT (RDNA4, gfx1201), Mesa 26.2.5 - DP-2: Gigabyte M27Q, 2560x1440 @ 169.83 Hz, VRR range 48-170 Hz - DP-1: second monitor, 2560x1440 @ 143.97 Hz - Both outputs: brightness 65% done by KWin in software (DDC/CI not allowed), color profile sRGB, colorPowerTradeoff = PreferEfficiency, HDR off GAME RV There Yet? (Unreal Engine 5.6, D3D12) through proton-cachyos 11.0-20261015 (vkd3d-proton), using Wine's Wayland driver. Running it through XWayland was also bad. OBSERVED The game renders at 80-168 fps (measured from the engine's own frame counter in its log), but during gameplay the motion looks like about 30 fps. It becomes smooth the moment KWin composites the game instead of scanning it out directly: - opening the in-game pause menu (the cursor becomes visible) - alt-tabbing away from the game - loading the Show FPS effect: qdbus6 org.kde.KWin /Effects org.kde.kwin.Effects.loadEffect showfps ISOLATION - Raising brightness from 65% to 100% on DP-2 (kscreen-doctor output.DP-2.brightness.100), with Show FPS unloaded so direct scanout is possible again: smooth. - Did not help: VRR off, in-game V-Sync on (FIFO instead of immediate), borderless instead of exclusive fullscreen. So it looks like any non-neutral color transform (Night Color temperature or software brightness) breaks frame pacing while a fullscreen client is directly scanned out. Since it also happens on RDNA4 with software brightness, the title could be broadened to cover both triggers. -- You are receiving this mail because: You are watching all bug changes.
