This post is aimed for beginners and explains what is qperf command and supplies few examples.

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References

• qperf(1): Measure RDMA/IP performance - Linux man page

qperf is a Linux command that measures bandwidth and latency between two nodes.  It can work over TCP/IP as well as the RDMA transports.

On one of the nodes, qperf is typically run with no arguments designating it the server node.

One may then run qperf on a client node to obtain measurements such as bandwidth, latency and cpu utilization.

Note: For optimal RDMA performance please use perftest package, that is the formal Open Fabrics performance test package (e.g. ib_send_bw, ib_write_bw ...) - click here for the package.

Setup

Two hosts connected back to back or via a switch.

Before you start, make sure there is an IP connectivity on the required link.

Run on one host to be considered as the qperf server:

# qperf

Run on the second node considered as a qperf client command from this format

# qperf <server-ip-or-hostname> <test>

For Example:

# qperf 21.21.21.7 tcp_bw tcp_lat

tcp_bw:

    bw  =  2634 MB/sec

tcp_lat:

    latency  =  7 us

The values that you get depends on the network bandwidth, connectivity and congestion.

More options are available on the main page.