dla always is off

[whk6688]

i run the command:

sudo python3 benchmark.py --model_name vgg19 --csv_file_path benchmark_csv/nx-benchmarks.csv --model_dir /home/wanghaikuan/code/jetson_benchmarks/download/

show: "Please close all other applications and Press Enter to continue..." then I pressed enter. cpu was low and i feel it did not start, then i pressed ctrl+c, i found it started. why?
and i found dla always is off.

thanks