Limit of multiple nvv4l2h264enc & nvvidconv instances at the same time

There are 3 nvvidconv plugins in the command but somehow there is no loading on VIC(hardware converter): VIC_FREQ 0%@192 This is a bit strange. For optimal throughput of hardware converter you can run the engine at max clock:
Nvvideoconvert issue, nvvideoconvert in DS4 is better than Ds5? - #3 by DaneLLL

Also you can run like:

nvv4l2h264enc --> fpsdisplaysink text-overlay=0 video-sink=fakesink

And check if the three pipelines can achieve target fps. Here is a C patch for reference:
FPS in test apps. - #2 by DaneLLL