Purpose: The script shows the rdma transfer rate[MB/s] for each rds connection.
It also shows histograms of inverse bandwidth in nsecs/KB [Avg number of nsecs
to transfer 1KB of data].

Arguments: None

Output format: [src-ip, dst-ip, tos, <r/w>] <Data transfer rate in MB/s>

Sample output: Shown below.
# ./rds_rdma_xfer_rate.d
2022 Oct 25 10:25:17
[<connection> op]                        MB/s
2022 Oct 25 10:25:27
[<192.168.100.125,192.168.100.124,0> r] 1059
2022 Oct 25 10:25:37
[<192.168.100.125,192.168.100.124,0> r] 1059
2022 Oct 25 10:25:47
[<192.168.100.125,192.168.100.124,0> r] 1056
2022 Oct 25 10:25:57
[<192.168.100.125,192.168.100.124,0> r] 1049
^C  << ---------- Press Cntr+c and stop the script to get histogram output.
2022 Oct 25 10:26:06 - Histogram of inverse bandwidth reported in nsecs/KB
[<192.168.100.125,192.168.100.124,0> r]

           value  ------------- Distribution ------------- count
             128 |                                         0
             256 |@@                                       15827
             512 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@   373157
            1024 |                                         3040
            2048 |                                         0

Transfer rdma bytes of 1 MB size.
# rds-stress
waiting for incoming connection on 0.0.0.0:4000
accepted connection from 192.168.100.124:34403 on 192.168.100.125:4000
negotiated options, tasks will start in 2 seconds
Starting up....
tsks   tx/s   rx/s  tx+rx K/s    mbi K/s    mbo K/s tx us/c   rtt us cpu %
   1      0   2411    2556.60 2467191.36       0.00    0.00     0.00 -1.00
   1      0   2403    2548.11 2458041.90       0.00    0.00     0.00 -1.00
   1      0   2502    2653.08 2559294.20       0.00    0.00     0.00 -1.00
   1      0   2382    2525.92 2436633.90       0.00    0.00     0.00 -1.00
   1      0   2396    2540.57 2449799.92       0.00    0.00     0.00 -1.00

# rds-stress -r 192.168.100.124 -s 192.168.100.125 -D 1M -o -M 1
connecting to 192.168.100.125:4000
negotiated options, tasks will start in 2 seconds
Starting up....
tsks   tx/s   rx/s  tx+rx K/s    mbi K/s    mbo K/s tx us/c   rtt us cpu %
   1   2410      0    2557.84       0.00 2466458.36   75.45   402.28 -1.00
   1   2401      0    2548.27       0.00 2458193.82   74.44   404.07 -1.00
   1   2499      0    2652.33       0.00 2558571.75   72.08   387.50 -1.00
   1   2380      0    2525.99       0.00 2436703.32   74.09   407.52 -1.00

# ./rds_rdma_xfer_rate.d
2022 Oct 25 10:32:05
[<connection> op]                        MB/s
2022 Oct 25 10:32:15
[<192.168.100.125,192.168.100.124,0> r] 2365
2022 Oct 25 10:32:25
[<192.168.100.125,192.168.100.124,0> r] 2424
2022 Oct 25 10:32:35
[<192.168.100.125,192.168.100.124,0> r] 2398
2022 Oct 25 10:32:45
[<192.168.100.125,192.168.100.124,0> r] 2443
^C
2022 Oct 25 10:32:47 - Histogram of inverse bandwidth reported in nsecs/KB
[<192.168.100.125,192.168.100.124,0> r]

           value  ------------- Distribution ------------- count
              64 |                                         0
             128 |                                         1
             256 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 101206
             512 |                                         1
            1024 |                                         0