https://bugs.kde.org/show_bug.cgi?id=504188
Bug ID: 504188
Summary: kwin_wayland defaults to llvmpipe (software rendering)
on Intel 11th Gen Iris Xe
Classification: Plasma
Product: kwin
Version: 6.3.4
Platform: Other
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: jacobnaon...@gmail.com
Target Milestone: ---
SUMMARY
kwin_wayland defaults to llvmpipe (software rendering) on Intel 11th Gen Iris
Xe, causing very high CPU usage; MESA_LOADER_DRIVER_OVERRIDE=iris fixes it.
STEPS TO REPRODUCE
- Use a system with an Intel 11th Generation CPU (i7-1165G7 in my case) with
integrated Iris Xe graphics.
- Install Kubuntu 25.04
- Log into a Plasma Wayland session.
OBSERVED RESULT
The kwin_wayland process consumes a very high percentage of CPU (80-90%) even
when the desktop is idle, causing the basically the entire system to lag,
including the cursor.
intel_gpu_top shows minimal (1-2%) usage on the "Render/3D" engine of the
integrated GPU
perf report for the kwin_wayland process shows that the majority of CPU time is
spent in llvmpipe and libgallium functions, so it's doing software rendering.
EXPECTED RESULT
kwin_wayland should utilize the Intel Iris Xe GPU for hardware-accelerated
rendering.
CPU usage for kwin_wayland should be low when the desktop is idle.
intel_gpu_top should show appropriate GPU level for desktop compositing.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 25.04
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.3
ADDITIONAL INFORMATION
CPU: Intel 11th Generation Core i7-1165G7 (with Iris Xe Graphics)
The X11 session works correctly with hardware acceleration and normal CPU
usage.
The issue is resolved by setting the environment variable
MESA_LOADER_DRIVER_OVERRIDE=iris for the Plasma Wayland session (by creating
~/.config/plasma-workspace/env/90-mesa_iris_override.sh with export
MESA_LOADER_DRIVER_OVERRIDE=iris and making it executable).
Initial perf report:
"Samples: 937K of event 'cycles:P', Event count (approx.): 915207451975
Children Self Command Shared Object Symbol
+ 12.52% 0.00% llvmpipe-0 libc.so.6 [.]
__GI___clone3
+ 12.52% 0.00% llvmpipe-0 libc.so.6 [.]
start_thread
+ 12.52% 0.00% llvmpipe-0 libgallium-25.0.3-1ubuntu2.so [.]
0x000078d4c57cfb9c
+ 12.51% 0.00%
llvmpipe-0 libgallium-25.0.3-1ubuntu2.so [.] 0x000078d4c5b9431f"
dmesg output (related to i915 or drm) shows the kernel driver loading, but
Wayland session still defaulted to llvmpipe
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