User Manual

Rev 4.60
Mellanox Technologies
103
8.4.2 ib_read_lat
ib_read_lat calculates the latency of RDMA read 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 reads the memory of the other side only after the other side have read his
memory. Each of the sides samples the CPU clock each time they read the other side memory , in
order to calculate latency. Read is availible only in RC connection mode (as specified in IB spec).
8.4.2.1 ib_read_lat Synopsys
8.4.2.2 ib_read_lat Options
The table below lists the various flags of the command.
-b, --bidirectional Measures bidirectional bandwidth (default unidirectional)
-V, --version Displays version number
-g, --grh Use GRH with packets (mandatory for RoCE)
ib_read_lat [-i(b_port) ib_port] [-m(tu) mtu_size] [-s(ize) message_size] [-t(x-
depth) tx_size] [-n iteration_num] [-p(ort) PDT_port] [-o(uts) outstanding reads] [-
a(ll)] [-V(ersion)] [-C report cycles] [-H report histogram] [-U report unsorted]
Table 33 - ib_read_lat Flags and Options
Flag Description
-p, --port=<port> Listens on/connect to port <port> (default 18515)
-d, --ib-dev=<dev> Uses IB device <device guid> (default first device found)
-i, --ib-port=<port> Uses port <port> of IB device (default 1)
-m, --mtu=<mtu> The mtu size (default 1024)
-o, --outs=<num> The number of outstanding read/atom(default 4)
-s, --size=<size> The size of message to exchange (default 65536)
-a, --all Runs sizes from 2 till 2^23
-t, --tx-depth=<dep> The size of tx queue (default 100)
-n, --iters=<iters> The number of exchanges (at least 2, default 1000)
-C, --report-cycles Reports times in cpu cycle units (default microseconds)
-H, --report-histogram Print out all results (default print summary only)
-U, --report-unsorted (implies -
H)
Print out unsorted results (default sorted)
-V, --version Displays version number
Table 32 - ib_read_bw Flags and Options
Flag Description