Significant cursor lag when running GPU-heavy full-screen apps
Affected version
- Mutter 40.1
- GNOME Shell 40.1
- Mesa 21.0.3
- Kernel 5.12.6
Hardware is an AMD Ryzen 5 3400G APU, 4K display @ 60Hz.
Observed effect is worse with Wayland than X.
Bug summary
When running (full screen) GPU-heavy application under a Wayland GNOME Shell session, there is significant lag in the movement of the mouse cursor (and the framerate of GNOME Shell animations drops significantly, although this is excusable given the GPU workload). A good example of an app which demonstrates this is Gaia Sky 3.0.3 (astro visualisation, available in Flathub). It can also be observed to a lesser extent with the game 0 A.D.
The cursor lag is less noticeable (but still there) when running GNOME Shell under X. Cursor lag is undetectable in the same circumstances under Plasma on Wayland.
The GPU clock appears to be scaling up correctly during these tests.
Steps to reproduce
- Start a Wayland-based GNOME session.
- Install and run the GPU-heavy app (such as Gaia Sky).
- If no cursor is present, hit the Super key to go to the Activities Overview and observe movement there.
What did you expect to happen
Movement of mouse cursor remains smooth despite GPU workload. Ideally, GPU priority given to desktop effects so they remain smooth, even if the application ends up dropping frames.