On Sat, 12 Feb 2005 22:52:46 +0300
Alexey Kuznetsov [off-list ref] wrote:

Exactly. That's why the next test should be with disabled TSO in 2.6.9.
If too rare PSHs were a problem, it will show as the same disaster there.

[ And, to be honest, in this case, I daresay MacOS X may be left with its bugs
  alone. Or we could help it with something like setting PSH when we are in slow
  start and each half of CWND after completion of slow start. Or just set
  PSH on each frame. ]

Setting it every other frame would fix the problem, just forcing it to
miss header prediction path is what is needed to avoid the silly delayed
ACK behavior.  And PSH is one way to do that.