To test the functionality of the IPoIB layer, it is possible to use any standard
IP network test tool and provide the
IP address of the IPoIB devices to be tested. For example, the ping command between the
IP addresses of the IPoIB devices should now work.
There are two different RDMA performance testing packages included with Red Hat Enterprise Linux, qperf and perftest. Either of these may be used to further test the performance of an RDMA network.
However, when using any of the applications that are part of the perftest
package, or using the qperf
application, there is a special note on address resolution. Even though the remote host is specified using an
address or host name of the IPoIB device, it is allowed for the test application to actually connect through a different RDMA interface. The reason for this is because the process of converting from the host name or
address to an RDMA address allows any valid RDMA address pair between the two machines to be used. If there are multiple ways for the client to connect to the server, then the programs might choose to use a different path if there is a problem with the path specified. For example, if there are two ports on each machine connected to the same InfiniBand subnet, and an
address for the second port on each machine is given, it is likely that the program will find the first port on each machine is a valid connection method and use them instead. In this case, command-line options to any of the perftest programs can be used to tell them which card and port to bind to, as was done with ibping
in Section 9.5, “Testing Early InfiniBand RDMA operation”
, in order to ensure that testing occurs over the specific ports required to be tested. For qperf
, the method of binding to ports is slightly different. The qperf
program operates as a server on one machine, listening on all devices (including non-RDMA devices). The client may connect to qperf
using any valid
address or host name for the server. Qperf
will first attempt to open a data connection and run the requested test(s) over the
address or host name given on the client command line, but if there is any problem using that address, qperf
will fall back to attempting to run the test on any valid path between the client and server. For this reason, to force qperf
to test over a specific link, use the
options to the qperf
client in order to force the test to run on a specific link.