> > We can see a substantial drop in performance around packet
> > sizes of 100 bytes and 200 bytes. I assume this is a driver
> > problem.
>
> You aren't using the de driver by any chance?

Yes, he is.

I sent him a copy of matt's recent commit message for the de
driver which fixes a "transmit stall" problem.  I think the fact
that he gets improved performance when having the interface in
promiscuous mode fits well with the description in the commit
message, where a receive interrupt would (re)start the stalled
transmitter.

- H=E5vard