Low GPU utilization

Hi, I use the code DQN, I can run the code successfully, but I find the GPU utilization is really low, about 8%. I use the 2080Ti and I use the GPU by adding the code at the begining of the DQN file.

import os

os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
os.environ["CUDA_VISIBLE_DEVICES"] = "0"

How can I improve the GPU utilization? Thanks!!