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?