User Manual

Rev 2.2-1.0.1
Mellanox Technologies
281
9.5.6 ib_write_lat
ib_write_lat calculates the latency of RDMA write operation of message_size between a pair of
machines. One acts as a server and the other as a client. They perform a ping pong benchmark on
which one side RDMA writes to the other side memory only after the other side wrote on his
memory. Each of the sides samples the CPU clock each time they write to the other side memory,
in order to calculate latency.
Synopsis
Server
ib_write_lat [options]
Client
ib_write_lat [options] <hostname>
Options
The table below lists the various flags of the command.
--pkey_index=<pkey index> PKey index to use for QP
--report-both Report RX & TX results separately on Bidirectinal BW
tests
--report_gbits Report Max/Average BW of test in Gbit/sec (instead of
MB/sec)
--run_infinitely Run test forever, print results every <duration> seconds
Table 55 - ib_write_lat Flags and Options
Flag Description
-a, --all Run sizes from 2 till 2^23
-c, --connection=<RC/XRC/UC/
DC>
Connection type RC/XRC/UC/DC (default RC)
-C, --report-cycles Report times in cpu cycle units (default microseconds)
-d, --ib-dev=<dev> Use IB device <dev> (default first device found)
-D, --duration Run test for a customized period of seconds.
-f, --margin Measure results within margins. (default=2sec)
-h, --help Show this help screen.
-H, --report-histogram Print out all results (default print summary only)
-i, --ib-port=<port> Use port <port> of IB device (default 1)
Table 54 - Additional ib_write_bw Flags and Options
Flag Description