I'm running Linux 1.3.59 and I see funny behavior with
large packets. We've got a Myrinet card in the
machine that has an MTU of 8432 bytes. Perhaps
Linux hasn't ever needed to deal with messages larger
than 4k?
In the test below, the sender is a Pentium Linux box
and the receiver is an UltraSparc.
UDP UNIDIRECTIONAL SEND TEST to mercury-t
Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec
32767 16 5.00 38276 0 0.98
65536 5.00 25101 0.64
32767 32 4.99 39106 0 2.01
65536 4.99 25924 1.33
32767 64 4.99 35958 0 3.69
65536 4.99 25434 2.61
32767 128 5.00 32272 0 6.61
65536 5.00 24575 5.03
32767 256 4.99 30747 0 12.61
65536 4.99 23231 9.53
32767 512 5.00 23738 0 19.46
65536 5.00 22950 18.81
32767 1024 5.00 14321 0 23.47
65536 5.00 14320 23.46
32767 2048 5.00 7849 0 25.74
65536 5.00 7849 25.74
32767 4096 4.99 4154 0 27.25
65536 4.99 4154 27.25
32767 8192 4.99 6 0 0.08
65536 4.99 6 0.08
32767 16384 4.99 3 0 0.08
65536 4.99 3 0.08
32767 32768 4.99 1 0 0.05
65536 4.99 1 0.05