https://bugs.kde.org/show_bug.cgi?id=496941
Bug ID: 496941
Summary: Compositor performance slow with Nvidia GPU, AMD iGPU
Classification: Plasma
Product: kwin
Version: 6.2.4
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: performance
Assignee: kwin-bugs-n...@kde.org
Reporter: glora...@icloud.com
Target Milestone: ---
SUMMARY
Hello!
I have a laptop with an Nvidia GPU, and an AMD iGPU. The setup is as follows:
for the internal display, and HDMI port, the Nvidia GPU's output is passed
through the iGPU, and when using a USB-C DisplayPort, the output is directly
connected to the Nvidia GPU.
When connecting to the DisplayPort, to the dGPU, the performance of KWin
degrades severely, and can't maintain a smooth refresh rate (I know the
performance overlay isn't supposed to be used for debugging; it reports a quite
low ~40fps though, which feels about right for what I'm seeing). The monitor
connected in this case is a 1440p 165Hz display. HDR and VRR do not make any
difference.
Connecting this display through the HDMI port, which passes through the iGPU,
everything fine. Higher resolution displays also do work smoothly when they are
connected to the HDMI port. The only difference I found in that case, is that
the kwin_wayland process uses the iGPU for compositing, and when connected
directly to the dGPU, it uses that Nvidia card for compositing.
I'm not sure how to go about troubleshooting this issue, if anything is needed
from the system, do ask. Thanks!
STEPS TO REPRODUCE
1. Have a laptop with an AMD iGPU and Nvidia dGPU
2. Connect directly to Nvidia dGPU
3. Observe
OBSERVED RESULT
Performance of the compositor is degraded when rendered with the dGPU.
EXPECTED RESULT
Performance of the compositor is on par with, or better than the iGPU, when
using the more powerful dGPU.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.0
Kernel Version: 6.12.1-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800HS with Radeon Graphics
Memory: 15.0 GiB of RAM
Graphics Processor: AMD Radeon Graphics
ADDITIONAL INFORMATION
Nvidia driver version: 565.57.01
dGPU: NVIDIA GeForce RTX 3050 Laptop GPU
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