Kwin_wayland High CPU Usage and black screen after sleep on Fedora KDE 43

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Hello Fedorans!

This is a solution topic of the titled issue what may help other users.

High CPU Usage by kwin_wayland on Fedora 43 KDE (Wayland + AMD GPU)

Symptoms:

  • kwin_wayland process consuming 30-90% CPU usage after login
  • System becomes sluggish, fans spin up
  • Mesa logs show fallback to software rendering (llvmpipe)
  • No /dev/dri/renderD128 present
  • KDE Wayland session lacks GPU acceleration

Diagnosis:

Hardware

lspci | grep -i vga

01:00.0 VGA compatible controller: NVIDIA Corporation TU117M [GeForce GTX 1650 Ti Mobile] (rev a1)

05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir [Radeon Vega Series / Radeon Vega Mobile Series] (rev c6)

Kernel modules:

lsmod | grep amdgpu
→ amdgpu loaded

lsmod | grep nouveau
→ nouveau also loaded (potential DRM conflict)

journalctl --user -b | grep kwin_wayland

Mesa logs:

Failed to open drm node
No render nodes have been found
ZINK: failed to choose pdev
Falling back to llvmpipe

GRUB configuration:

GRUB_CMDLINE_LINUX="rhgb quiet nomodeset"

nomodeset disables early GPU driver init

Solution Steps

1. Remove nomodeset, enable render nodes

Edit GRUB:

sudo nano /etc/default/grub

Change the line:

GRUB_CMDLINE_LINUX="rhgb quiet drm.rnodes=1"

Then update the grub:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

2. Disable nouveau to avoid DRM conflicts

echo "blacklist nouveau" | sudo tee /etc/modprobe.d/disable-nouveau.conf
sudo dracut --force

3. (Optional ! ) Downgrade Mesa to stable 24.x

sudo dnf5 downgrade mesa-dri-drivers mesa-libGL mesa-vulkan-drivers

4. Reboot

reboot

5. Confirm GPU acceleration is active

ls /dev/dri | grep render
→ renderD128 ✅

To be sure llvmpipe is not primary

glxinfo | grep "OpenGL renderer"

OpenGL renderer string: AMD Radeon Graphics (radeonsi, renoir, ACO, DRM 3.64, 6.17.5-300.fc43.x86_64)

Outcome

  • kwin_wayland CPU usage normalized
  • Mesa uses hardware acceleration (no more llvmpipe)
  • /dev/dri/renderD128 present
  • KDE Wayland session is stable and responsive
  • Sleep/wake cycle works without black screen

I could not mark as solution, may admins check it.

2

Marking as solution for the OP

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