ib_write_bw doesnt show BW peak

[marcomontevechi1]

Hi, im using perftest to benchmark two servers in a point-to-point connection. After doing: ib_write_bw -D 10 -d mlx5_0 in server 1 and ib_write_bw -D 10 -d mlx5_0 <server_1_ip> n server two i get the result:

************************************
* Waiting for client to connect... *
************************************
---------------------------------------------------------------------------------------
                    RDMA_Write BW Test
 Dual-port       : OFF      Device         : mlx5_0
 Number of qps   : 1        Transport type : IB
 Connection type : RC       Using SRQ      : OFF
 PCIe relax order: ON
 ibv_wr* API     : ON
 CQ Moderation   : 1
 Mtu             : 4096[B]
 Link type       : Ethernet
 GID index       : 3
 Max inline data : 0[B]
 rdma_cm QPs     : OFF
 Data ex. method : Ethernet
---------------------------------------------------------------------------------------
 local address: LID 0000 QPN 0x0108 PSN 0x63ad7d RKey 0x17eedf VAddr 0x007f760c947000
 GID: 00:00:00:00:00:00:00:00:00:00:255:255:10:255:255:05
 remote address: LID 0000 QPN 0x0076 PSN 0xf3810c RKey 0x201600 VAddr 0x007fbb4c981000
 GID: 00:00:00:00:00:00:00:00:00:00:255:255:10:255:255:04
---------------------------------------------------------------------------------------
 #bytes     #iterations    BW peak[MB/sec]    BW average[MB/sec]   MsgRate[Mpps]
 65536      664644           0.00               6923.47        0.110775
---------------------------------------------------------------------------------------

Perftest's README seems to say that -N should disable peak monitoring but by default it is enabled. Why am i seeing peak BW equal to zero? Thanks

[sshaulnv]

You are using -D flag. this flag set the test type to be DURATION instead of ITERATIONS. when test type is DURATION, the BW peak calculation is disabled: https://github.com/linux-rdma/perftest/blob/c09edf9d2af30ad2d50b564d7e8aa977c05ce40d/src/perftest_parameters.c#L1210