David> I wish you had started the thread by mentioning this
    David> specific patch, we wasted an enormous amount of precious
    David> developer time speculating and asking for arbitrary tests
    David> to be run in order to narrow down the problem, yet you knew
    David> the specific change that introduced the performance
    David> regression already...

Sorry, you're right.  I was a little confused because I had a memory of
Michael's original email (http://lkml.org/lkml/2006/3/6/150) quoting a
changelog entry, but looking back at the message, it was quoting
something completely different and misleading.

I think the most interesting email in the old thread is
http://openib.org/pipermail/openib-general/2005-October/012482.html
which shows that reverting 314324121 (the "stretch ACK performance
killer" fix) gives ~400 Mbit/sec in extra IPoIB performance.

 - R.