Some use examples:
$ sudo latency_histogram.py -i eth0 -t src "dst port 26000"
$ sudo latency_histogram.py -i eth0 -t dst "src port 26000"
$ sudo latency_histogram.py -t dst --iface eth0 "src host 168.119.137.110"
$ sudo latency_histogram.py -t src --iface eth0 "dst host 168.119.137.110"
Example output: