Bug 513593 - Mouse lag on Nvidia Optimus on Wayland
Summary: Mouse lag on Nvidia Optimus on Wayland
Status: REPORTED
Alias: None
Product: kwin
Classification: Plasma
Component: libinput (other bugs)
Version First Reported In: 6.5.4
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-12-19 23:12 UTC by Alberto Salvia Novella
Modified: 2025-12-20 02:05 UTC (History)
2 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:

Attachments
Add an attachment

Note You need to log in before you can comment on or make changes to this bug.
Description Alberto Salvia Novella 2025-12-19 23:12:55 UTC 
PROBLEM
- On Wayland, if you run any game on the dGPU, the mouse will experience severe input lag.

CAUSE
- The mouse is still rendered by the iGPU, which is unaware that the dGPU is running at maximum speed. So the iGPU stays at its lowest clocks.

TEST-CASE
1. Download: https://www.thedarkmod.com
2. Run it with: __GLX_VENDOR_LIBRARY_NAME="nvidia" ./thedarkmod.x64
3. Move the cursor around

SYSTEM
- Zenned OS
- Plasma 6.5.4
- Frameworks 6.21.0
- Qt 6.10.1
Comment 1 Alberto Salvia Novella 2025-12-19 23:16:41 UTC 
Here's how to temporally max the iGPU clocks:

On Intel:
cat /sys/class/drm/card*/gt_RP0_freq_mhz | sudo tee /sys/class/drm/card*/gt_min_freq_mhz

On AMD:
echo performance | sudo tee /sys/class/drm/card*/device/power_dpm_force_performance_level
Comment 3 Alberto Salvia Novella 2025-12-19 23:28:24 UTC 
Still I don't know if this shall be fixed in kwin, or in the nvidia-persistenced daemon in nvidia-open.

For the time being I have worked-around the bug on optimus-manager:
https://github.com/Askannz/optimus-manager/commit/d3376ef0a2fc2f5a9901790a8ee358125fc63951