You may need multiple terminals to run many workers, but the here's what will run the master;
locust -f benchmark.py --host http://0.0.0.0:8000 -u 2000 -r 50 --master
This is what will spin up a worker.
locust -f benchmark.py --worker --master-bind-host=0.0.0.0 --master-bind-port 8089