[BUG] vrserver high CPU use

[baracoder]

Describe the bug
vrserver uses 100% of a CPU core, even without any headset connected. CPU usage is much lower with WiVRn.
If other users don't observe this, it could be related to my dual GPU setup: Radeon 880M onboard and Radeon RX 9070 XT eGPU. Or it could be related to the virtual screen as it stays black. Using GNOME.

To Reproduce
Steps to reproduce the behavior:

1. Start SteamVR
2. Check CPU usage in htop - vrserver uses 100% CPU, 1 core

Expected behavior
A clear and concise description of what you expected to happen.

System Information (please complete the following information):
Please use the latest Steam beta client and SteamVR beta for your bug reports!

• Steam client version (build number or date): 1768528184
• SteamVR version: 2.14.5
• Distribution (e.g. Ubuntu): NixOS, Bazzite
• Steam runtime diagnostics: runtime-diag.txt
• Steam and SteamVR logs: steam-logs.tar.gz
• Minidumps: (No files found)

Additional context
Add any other context about the problem here.

[yoyobuae]

I've found the exact cause of this problem.

The CVRPipewireAppManager::PipewireThread() function in vrserver is constantly spinning and eating CPU cycles. Binary patching the function to instead return gets rid of the increased CPU use.

[misyltoad]

Thanks for the report. Can you send the output of pw-dump when in the bad state?

Ie. pw-dump &> dump.json and send the dump.json. Thanks!

[baracoder]

Great find! The screen mirror in SteamVR stays black for me, sometimes I can still move the cursor. I also experienced problems with wayvr screen mirroring when using Steam VR. That is also using pipewire with GNOME. Maybe this is related wayvr-org/wayvr#270

[KibblesTheKitten]

@baracoder steamvr can not capture the desktop on Wayland. For it you have to use x11. Or use wayvr. You could try using the x11 Wayland video bridge, but there is a chance of it being VERY unreliable. Steamvr desktop capture is already hit or miss on x11

[kitlith]

@misyltoad

here's dump.json from my system, while observing ~100% CPU usage from vrserver