[ofa-general] [Bug 450] New: IPoIB BW drop (measured with iperf) with mtu=1500 on x86 RH4UP3

[bugzilla-daemon at lists.openfabrics.org]

https://bugs.openfabrics.org/show_bug.cgi?id=450

           Summary: IPoIB BW drop (measured with iperf) with mtu=1500 on x86
                    RH4UP3
           Product: OpenFabrics Linux
           Version: 1.2alpha1
          Platform: X86
        OS/Version: RHEL 4
            Status: NEW
          Severity: major
          Priority: P2
         Component: IPoIB
        AssignedTo: bugzilla at openib.org
        ReportedBy: monil at voltaire.com


Reproduced by using iperf default parameters TCP BW test (iperf -s / iperf -c
-i 1) over ipoib ibterface with mtu=-1500, on _32bit_ RH4-U3 we see major
performance drop (from 1.3Gb downto 50Mb).

We do not see the same behavior on 64 bit OS or mtu=2044.


[root at src2 ~]# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 MByte (default)
------------------------------------------------------------
[  4] local 172.16.0.120 port 5001 connected with 172.16.0.121 port 35022
[  4]  0.0-28.6 sec  3.52 GBytes  1.06 Gbits/sec

[root at sink2 ~]# iperf -c 172.16.0.120 -i 1 -t 1000
------------------------------------------------------------
Client connecting to 172.16.0.120, TCP port 5001
TCP window size: 8.00 MByte (default)
------------------------------------------------------------
[  3] local 172.16.0.121 port 35022 connected with 172.16.0.120 port 5001
[  3]  0.0- 1.0 sec    153 MBytes  1.28 Gbits/sec
[  3]  1.0- 2.0 sec    153 MBytes  1.29 Gbits/sec
[  3]  2.0- 3.0 sec    153 MBytes  1.29 Gbits/sec
[  3]  3.0- 4.0 sec    153 MBytes  1.28 Gbits/sec
[  3]  4.0- 5.0 sec    153 MBytes  1.29 Gbits/sec
[  3]  5.0- 6.0 sec    153 MBytes  1.29 Gbits/sec
[  3]  6.0- 7.0 sec    153 MBytes  1.28 Gbits/sec
[  3]  7.0- 8.0 sec    153 MBytes  1.28 Gbits/sec
[  3]  8.0- 9.0 sec    153 MBytes  1.28 Gbits/sec
[  3]  9.0-10.0 sec    153 MBytes  1.28 Gbits/sec
[  3] 10.0-11.0 sec    154 MBytes  1.29 Gbits/sec
[  3] 11.0-12.0 sec    154 MBytes  1.29 Gbits/sec
[  3] 12.0-13.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 13.0-14.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 14.0-15.0 sec    153 MBytes  1.28 Gbits/sec
[  3] 15.0-16.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 16.0-17.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 17.0-18.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 18.0-19.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 19.0-20.0 sec    153 MBytes  1.28 Gbits/sec
[  3] 20.0-21.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 21.0-22.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 22.0-23.0 sec    153 MBytes  1.29 Gbits/sec
[  3] 23.0-24.0 sec  44.3 MBytes    372 Mbits/sec
[  3] 24.0-25.0 sec  7.92 MBytes  66.5 Mbits/sec
[  3] 25.0-26.0 sec  7.98 MBytes  66.9 Mbits/sec
[  3] 26.0-27.0 sec  7.97 MBytes  66.8 Mbits/sec
[root at sink2 ~]#


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