[PERF] Stuttering in Index

[reinux]

Describe the bug

I'm getting stuttering that looks like this:

Wouldn't be surprised if this has something to do with my NixOS config, which means it isn't the same environment as a more complete distro, but I'd appreciate any help I can get!

System Information (please complete the following information):

• Distribution: NixOS
• SteamVR version: 2.7.4
• Steam client version: 1726604483
• Opted into Steam client beta?: No
• Graphics driver version: 560.35.03
• Gist for SteamVR System Information: https://gist.github.com/reinux/9b6d709834c5ababf7af4f38ddb61e32

Performance Data (optional, but very helpful):

• CPU: Ryzen 7 3700X
• GPU: RTX 4090
• Gist for perf top: https://gist.github.com/reinux/4693ba310f781c8cc8e4c512a8c53479
• Link to gpuvis trace: (Can't capture)

Additional context

Seems to be similar to #219 .

Note: Commenters who are also experiencing this issue are encouraged to include the "System Information" and "Perf Data" sections in their replies.

[Corben78]

Stuttering has been reported since 555 driver, which enables the GSP firmware by default.
It can be disabled by kernel parameter nvidia.NVreg_EnableGpuFirmware=0 for the 555 driver, but not for 560 anmore:
NVIDIA/open-gpu-kernel-modules#667

[reinux]

Ah, nuts. Unless I'm missing something, it looks from discussions like there's no plan to address it yet either. I think 555 was giving me stability issues, but I'll give it a try again in a bit to see if that's the cause.

[toqu]

The kernel parameter nvidia.NVreg_EnableGpuFirmware=0 still works as expected with the 560 non-open driver.

NVIDIA/open-gpu-kernel-modules#667 states that the parameter is not working when the open driver is used.

I've double checked on my bench and can confirm that SteamVR stutters horribly with the default parameters. Supplying nvidia.NVreg_EnableGpuFirmware=0 improves the performance significantly.

[reinux]

That worked. Thanks!

Should we leave this open or close it? I'm not sure if this is something that can be addressed from the SteamVR side or if it's an nvidia issue.

[Corben78]

Thanks for the clarification. I remembered reading that on Linux the 560 driver would default to open kernel modules and no longer provide the closed ones.
I just tested myself with the nvidia-driver-560 package (not nvidia-driver-560-open) from the Ubuntu PPA, and it still works to disable the GSP firmware usage.