#3 Flow control is not correct

[Greg Humphreys]

Because we use full MTU sized buffers on the server
side, and sometimes re-use those buffers, it's very
hard for the client to actually tell how much of the
server's memory it's using.

However, it's current estimate is very optimistic, and
the server can in fact be easily overrun if the
buffers are too large (try running psubmit with a one-
megabyte MTU, and watch your system's memory get
consumed quickly).