Ran iperf3 on my Mellanox ConnectX-4 100 Gbps IB card:
ran with the command:
server:
iperf -s
client:
iperf -c <<ip>> -i 1 -P 4
92.7 Gbps (out of 100 Gbps possible). Not too shabby and ALMOST the 96-97-ish Gbps that I am able to get with the Infiniband bandwidth testing/benchmarking tools.
(This is between two AMD Ryzen 9 5950X client nodes via a Mellanox externally managed MSB-7890 36-port 100 Gbps IB switch.)