qperf“, is one of the many tools used to measure bandwidth and latency between two nodes. qperf works over many transports including TCP/IP, RDMA, UDP, and SCTP. qperf measures throughput on different sockets in the IP stack.
To install qperf on a RedHat Based systems, use the below command.
# yum install qperf
To lists available tests, use the below command:
# qperf --help tests# qperf --help tests Miscellaneous conf Show configuration quit Cause the server to quit Socket Based rds_bw RDS streaming one way bandwidth rds_lat RDS one way latency sctp_bw SCTP streaming one way bandwidth sctp_lat SCTP one way latency tcp_bw TCP streaming one way bandwidth tcp_lat TCP one way latency udp_bw UDP streaming one way bandwidth udp_lat UDP one way latency RDMA Send/Receive rc_bi_bw RC streaming two way bandwidth rc_bw RC streaming one way bandwidth rc_lat RC one way latency uc_bi_bw UC streaming two way bandwidth uc_bw UC streaming one way bandwidth uc_lat UC one way latency ...
qperf has the notion of a “client” and “server” for testing network throughput between two systems. To use qperf, configure 2 machines:
- On the listener, run qperf without options.
- On the other machine, run “qperf [hostname] [options to test]“.
Few of the most commonly used qperf options are :
See the man page of qperf for more options.
Open firewall ports for qperf
The qperf server listens on TCP Port 19765 by default. This can be changed with the –listen_port option. This port will need to be allowed in any firewall present.
# iptables -I INPUT -m tcp --dport 19765 -j ACCEPT
If you are not on production systems or do not need iptables or firewald to be enabled, you can go ahead and simply disable them.
Measuring Bandwidth with qperf
To measure the network bandwidth between 2 servers, we have to configure one of them to server as the listener as shown below.
Now we can have the other system connect to the listener as a client machine. Use the command below to do so.
# qperf 192.168.104.112 tcp_bw tcp_bw: bw = 314 MB/sec
192.168.104.112 – is the lister machine (Server) IP address.
As with any performance test, you should not rely on 1 iteration of the test. Try the above command 3 or more times to find an average value.
Measuring Latency with qperf
As with the above example, we need to start the listener on one of the machines.
Use the below command on the client-server in order to measure the latency between 2 servers.
# qperf -vvs 192.168.104.112 tcp_lat tcp_lat: latency = 311 us msg_rate = 3.22 K/sec loc_send_bytes = 3.22 KB loc_recv_bytes = 3.22 KB loc_send_msgs = 3,218 loc_recv_msgs = 3,217 rem_send_bytes = 3.22 KB rem_recv_bytes = 3.22 KB rem_send_msgs = 3,217 rem_recv_msgs = 3,217
As shown in the output above, latency value is 311 Microseconds and then there are few other details as well. loc_xx shows details from the local system perspective and rem_xx shows the same from the remote system perspective. Refer man page of qperf for more options/verbosity.
There are Other tests available with qperf, including UDP bandwidth and latency, SCTP bandwidth and latency, and other protocols which run on RDMA. See the TESTS section of man qperf for more details.