RUDP + round robin + > adapters = problem

  • Terry Lemons
    Terry Lemons


    I'm using SLES 9 SP3 on Dell servers with four Gigabit Ethernet ports to perform some performance tests that involve bonding.  I'm currently using round-robin balance policy.

    If I plug just one of the four GigE adapters in, and run my application (which uses RUDP), I see ~114 MB/s; that's acceptable for a GigE adapter

    But if I plug in two of the four GigE adapters, and run my RUDP-based application, I see only 48 MB/s.  Three and four adapters plugged in yielded 41 MB/s and 40 MB/s respectively.

    I did not notice this behavior when I ran iperf in TCP mode.
    I did not notice this behavior when I ran my RUDP application with alb balance policy.

    So, what could it be about the combination of round-robin balance policy AND RDUP (Reliable UDP) that causes performance to drop hideously when more than one Gigabit Ethernet adapter is plugged in?