https://bugs.kde.org/show_bug.cgi?id=527749
Bug ID: 527749
Summary: Night Color temperature causes severe frame-pacing
issues in fullscreen games
Classification: Plasma
Product: kwin
Version First unspecified
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: night color
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Summary
I've noticed a significant frame-pacing issue when using Night Color with a
non-neutral daytime temperature on KWin Wayland. On my system, running KDE
Plasma 6.8.1 with an AMD RX 6650 XT, setting the daytime temperature to 6000 K
makes fullscreen games feel extremely choppy, even when the FPS is high.
Disabling Night Color immediately restores smooth gameplay.
I've been able to reproduce this in CS2 (native Vulkan), Arc Raiders (Proton),
and The Witcher 3. The issue occurs regardless of resolution or whether VRR is
enabled. It also seems to have started recently, as I wasn't experiencing this
behavior before.
CachyOS, kernel 7.3.0-4-cachyos
KDE Plasma 6.8.1, Wayland, KWin 6.8.1
AMD Radeon RX 6650 XT, amdgpu, Mesa 26.2.5
Ryzen 7 5700X3D, governor set to performance
DP-1, 1920x1080 @ 180 Hz, VRR 48–180 Hz
Night Color configuration
[NightColor]
Active=true
Mode=1 # Automatic
DayTemperature=6000
At runtime, Night Color reports currentTemperature=6000, daylight=true, and
enabled=true.
Since 6000 K is different from the neutral 6500 K setting, a non-neutral color
transformation is applied even during the day.
Set Night Color to Automatic and configure the daytime temperature to 6000
K,launch a game in fullscreen mode, Observe that the FPS remains high, but the
motion looks noticeably uneven and stuttery.
Disable Night Color temporarily and the game immediately becomes smooth again.
Behavior
The games become visibly choppy even though the FPS counter remains high.
Switching virtual desktops temporarily fixes it: Switching to another virtual
desktop and back restores smooth motion for approximately three seconds, after
which the stuttering returns.
KWin reports repeated atomic commit failures: During gameplay, the logs contain
repeated messages like this:
kwin_wayland[1311]: Atomic commit failed: EBUSY
I've counted 73 occurrences during a single boot, often clustered around gaming
sessions, including 39 within one minute. These messages stop appearing when
Night Color is disabled.
Disabling VRR doesn't help: Running kscreen-doctor output.DP-1.vrrpolicy.never
makes no noticeable difference.
Hypothesis
My suspicion is that applying a non-neutral color transformation prevents the
game's buffer from being promoted to a direct scanout plane. If that happens,
KWin may need to composite and transform every frame instead of letting the
display scan out the game's buffer directly.
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