In message <20010330154220.A13461@recourse.net>Michael Lyle writes

>On linux, we do about 97mbit/sec (filling up the TX rings on the card,
>so this corresponds to network saturation).  On NetBSD, we can do only
>about 65-70mbit/sec.  I have a feeling this has to do with serialization
>of various TCP/driver operations.  I've experimented lightly with turning
>up window sizes etc and it doesn't seem to have much effect.

Problems like this are hard to reproduce, which makes them hard to
diagnose. A timestamped `tcpdump' trace would show the dynamics of the
acutal TCP behaviour. That would give a lot of insight into what is
actually happening.

Exactly which kernel version are you using?  The 1.5 release, or
something else?  There were some issues with de-tuning checksum
throughput on certain kernel versions.

Also, are the two machines connected via a switch, or a shared medium?