https://bugs.kde.org/show_bug.cgi?id=520748
Bug ID: 520748
Summary: UI Freeze in xdg-desktop-portal-kde (file picker) when
secondary headless NVIDIA GPU is under 100% compute
load on Wayland
Classification: Plasma
Product: xdg-desktop-portal-kde
Version First unspecified
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
1. System Environment
* OS: CachyOS (Arch Linux based)
* Desktop Environment: KDE Plasma (Wayland session)
* GPU 1 (Compute/Headless): NVIDIA RTX 3090 (card1)
* GPU 2 (Display): NVIDIA GTX 1660 Super (card2)
* NVIDIA Driver: Proprietary 595.71.05
* Browser: Firefox 151.0.2 (Native Wayland)
2. Description of the Problem
I am using a dual-GPU setup where my display is physically connected
exclusively to the GTX 1660 Super (card2). The RTX 3090 (card1) is used purely
as a headless compute card for heavy AI generation tasks (e.g., PyTorch/CUDA
via ComfyUI).
When the RTX 3090 is under 100% compute load, opening a file picker dialog (via
xdg-desktop-portal-kde) from the browser causes the entire desktop/UI to freeze
or stall for several seconds before the dialog finally appears.
3. Steps to Reproduce
1. Run a heavy CUDA/compute workload strictly on the headless GPU (RTX 3090 /
card1), pushing it to 100% utilization.
2. Ensure the Wayland session and the browser are running on the display GPU
(GTX 1660 Super / card2).
3. In the browser, trigger an action that opens the system file picker (e.g.,
clicking an "Upload Image" button).
4. Expected Result
The file picker dialog should open instantly, as the display GPU (1660 Super)
is completely idle and should handle the UI rendering independently.
5. Actual Result
The system file picker hangs for a few seconds. It appears that KDE/Portal is
aggressively polling all DRM/EGL devices (including the heavily saturated RTX
3090) before drawing the dialog, and the NVIDIA driver is blocking/timing out
the response due to the extreme compute load.
6. Additional Context & Troubleshooting Done
* I have explicitly set KWIN_DRM_DEVICES=/dev/dri/card2 in /etc/environment to
force KWin to ignore card1.
* The issue persists despite these workarounds. Drag-and-dropping files
directly from Dolphin to the browser bypasses the freeze entirely, confirming
the issue is strictly related to the xdg-desktop-portal-kde initialization /
GPU polling mechanism.
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