Way to check if GPU is currently being used without preventing it from going into D3cold (powered off)?

[qwertychouskie]

As far as I can tell, any query through NVML/nvidia-smi will keep the GPU awake even when it would otherwise go into D3cold (a.k.a. powered off). This creates a problem for any system monitor utility that monitors GPU usage in that they will cause significant battery drain on laptops by keeping the dGPU powered on.

cat /sys/class/drm/card1/device/power_state will tell me if the device is already in D3cold, but it only switches after around 10 seconds of inactivity, while most system monitors refresh around once per second, and each refresh resets that ~10 second timer, meaning the GPU never sleeps.

One weird behavior I have noted is that NVML queries take much longer (~800ms to query all the displayed data vs ~200ms) if nothing else is active on the dGPU, even though it is not powered off.

This issue isn't exclusive to the open kernel module, but this is the best place I found to ask.

See also https://gitlab.com/mission-center-devs/mission-center/-/issues/30 and Syllo/nvtop#230