Bug ID 4341092: ~40% permanent GPU usage, but all GPU processes are idle (Ubuntu 23.10)

nvtop showing ~40% permanent usage, with all gpu processes idle (since Ubuntu 23.10 - see screenshot)

I have tried killing off gpu processes but it nothing seems to have an effect.
Running latest Gnome 45 desktop. Dual 2060RTX, x399 TR4 mobo.

I thought nvtop detects all GPU-bound processes?

Thinking maybe Nsight Shader Profiler might give some insight into this mystery.
Is that the right way to determine what this mysterious load is actually doing?

Can you please attach a bug report log?

If your screen configuration is using the composition pipeline then that might explain the usage. Note that both the GPU core and the memory are running at very low clock frequencies so even the minimal load generated by the composition pipeline could easily account for 40% usage.

I am away from the lab right now, but found this was already reported here.

@generix gave the same answer you just did (high % at low freq) so pretty sure it is the composition pipeline (it is enabled for both my dual monitors).

Strange I did not see it until the major version upgrade of 23.10 (same hardware).
Possibly a similar bug has resurfaced in the kernel modules, not at the process level.
Will generate a bug report log before I apply the solution and attach it here.

Thanks very much.

Meanwhile, back in the lab … it was indeed the composition pipeline causing this behaviour.

I had to turn off Force Composition Pipeline in nvidia-settings for both of my dual displays to resolve this issue.
If even just one display has this setting, the ‘high % at low freq’ issue returns.

As requested, please find the nvidia-bug-report.log attached to Bug ID: 4341092 (I generated this before turning off the composition pipeline).

Note: not seeing any screen tearing with Force Composition Pipeline in nvidia-settings off. I see that Gnome 45 includes the latest mutter compositor. Been using Nvidia/Linux systems for a long time so forcing the composition pipeline on was just a (very) old habit.

Note: it would be nice of nvtop included kernel level GPU usage stats. I honestly thought I had some sort of crypto/AI malware infection when nvtop GPU process level stats reported no activity (0% usage - see above screenshot).

Thanks again.

Is it possible that the GPU was locked to a higher clock in the older configuration? The utilization percentage is a function of the power state and there have been a few power improvements here and there.

There was no GPU locking in Gnome/22.04 afaik. Nor did I force any freq locks.

Seems to be a regression, since this issue has surfaced before and was fixed.

It seems to stem from both the Gnome compositor and the NV compositor running at the same time. Could be a Gnome regression.

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