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[PERF] Constant stuttering, possibly caused by two 'vrserver' processes taking up 100% of a core each

steamvrclosed perf
ValveSoftware/SteamVR-for-Linux#726 · opened 2024-07-25 by ZhenyaPav · updated 2024-07-29 · 3 comments · github
ZZhenyaPav 2024-07-25 github

Describe the bug
Until about a month ago, SteamVR has worked quite smooth with ALVR, but now it is constantly stuttering, which can be seen both in the headset and on ALVR latency graph. The issue is present constantly, even when no game is launched, but is not visible on vrmonitor's timing graph

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Render latency (bottom gray part) is constantly changing up and down by about 5ms.

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In htop, I have noticed two vrserver processes, both with 100% CPU usage (so completely using one core each). This has not been the case before the issue appeared.

To Reproduce
Steps to reproduce the behavior:

  1. Start ALVR and SteamVR

Expected behavior
Little to no stuttering in the headset, smooth latency graph in ALVR.

System Information (please complete the following information):

  • Distribution: Arch
  • Desktop Environment: KDE Plasma on Wayland
  • SteamVR version: Beta 2.7.4, but also reproducible with non-beta and previous release.
  • Steam client version: 1.0.0.79-2
  • Opted into Steam client beta?: No
  • Graphics driver version: Mesa 24.1.4-arch1.2
  • Gist for SteamVR System Information: https://gist.github.com/ZhenyaPav/57e9ec9a68c9acab4d705413f63084ae

Performance Data (optional, but very helpful):

  • CPU: Ryzen 5600X
  • GPU: Radeon 7900XT
ZZhenyaPav 2024-07-25 github

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Also noticed that the render latency reported by ALVR is considerably higher than what SteamVR graph shows

ZZhenyaPav 2024-07-26 github

Asked around on Monado discord - there is at least one person on Arch with AMD GPU that has this issue as well, so it's likely not related to SteamVR.

ZZhenyaPav 2024-07-29 github

The issue has been fixed on ALVR side.

Nothing extracted yet.