If you are using DeepStream docker, there is /opt/nvidia/deepstream/deepstream/user_deepstream_python_apps_install.sh script to help you to install the necessary packages. You can copy the script out if you are working in local.
@Fiona.Chen I have tried your .c code in both deepstream-7.0 and deepstream-7.1 and still process getting created in GPU-0.
Please repeat the same deepstream_test3_app.c you have provided again and check if any process getting created in GPU-0 also. Run it for atleast 10 minutes and share us the nvidia-smi image as below for our better understanding.