GPU is enabled automatically

Hi all,
I am using the Jetson AGX Xavier board with Ubuntu 18.04.
Also, I am using YoloV3 with a camera and ROS to classify obstacles (darknet_ROS).
In the mentioned tutorial, there are some steps to enable GPU by using a CUDA (such as GPU = 1 CUDNN =1 OPENCV = 1).
But I noticed that when I ran YoloV3, the GPU is activated even without doing these steps (figure below).
My question: does the GPU is activated automatically when I launch the YoloV3?
Thank you.

CUDA 10.2 and cuDNN 8.0 are installed.
The link for YoloV3


Maybe GPU is used for other tasks, like rendering.
You can use profile to check if there is any CUDA job.