User guide

A–Benchmark Programs
Benchmark 2: Measuring MPI Bandwidth Between Two Nodes
IB0054606-02 A A-5
Typical output might look like:
# OSU MPI Bandwidth Test v3.1.1
# Size Bandwidth (MB/s)
1 2.35
2 4.69
4 9.38
8 18.80
16 34.55
32 68.89
64 137.87
128 265.80
256 480.19
512 843.70
1024 1353.48
2048 1984.11
4096 2152.61
8192 2249.00
16384 2680.75
32768 2905.83
65536 3170.05
131072 3224.15
262144 3241.35
524288 3270.21
1048576 3286.05
2097152 3292.64
4194304 3283.87
The increase in measured bandwidth with the messages’ size is because the
contribution of each packet's overhead to the measured time becomes relatively
smaller.