This is not a real issue to me, just reporting here as this behavior looks surprising to me. NVIDIA may check further.
I’m using a Xavier NX R32.4.3 and v4l2loopback 0.10 from dkms:
# Install v4l2loopback and utils
sudo apt-get update
sudo apt-get install v4l2loopback-dkms v4l2loopback-utils
# Create a virtual video node /dev/video1
sudo modprobe v4l2loopback exclusive_caps=1 video_nr=1
# The following command triggers this strange behavior. It doesn't happen if not using sudo.
# Not related to format nor resolution.
sudo v4l2loopback-ctl set-caps "video/x-raw, format=BGRx, width=640, height=480" /dev/video1
# Now this simple gstreamer pipeline that should not involve TF nor CUDA in this case stalls for 2 seconds and gives this trace from TF before starting:
gst-launch-1.0 videotestsrc ! video/x-raw, format=BGRx, width=640, height=480, framerate=30/1 ! identity drop-allocation=true ! v4l2sink device=/dev/video1
2020-08-15 13:03:56.920524: I tensorflow/stream_executor/platform/default/dso_loader.cc:48] Successfully opened dynamic library libcudart.so.10.2
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Pipeline is PREROLLED ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
...
Any idea what happens in this case ?
I have deepstream-5.0 installed and I suspect it’s related, but I cannot understand the difference after configuring the v4l2loopback node with sudo.
Indeed, this message is issued when gstreamer rebuilds the cache with deepstream plugins.
Do you have any idea why this v4l2loopback-ctl command with sudo triggers rebuilding the cache for standard user ?
This might be rather a gstreamer or v4l2loopback issue, but any sharing would be welcome for a better understanding.
Sorry I missed that topic update. The issue is that the above command invalidates gst cache…No idea why.
Clearing cache results in 2 extra seconds for rebuilding and extra trace.
Note that it happens only this special way (sudo v4l2loopback-ctl) that triggers this issue. No problem without sudo, or if later using sudo for gst-launch.