K 10
svn:author
V 6
adrian
K 8
svn:date
V 27
2011-09-05T06:11:17.610502Z
K 7
svn:log
V 1119
Make the default rate choice semi 11n aware.

There's a couple of bugs here which I'm trying to fix:

* There's a bit of code which marks all larger size bins as having failures
  if a smaller bin has a failure.
* If there's no large packet TX (say I'm doing an iperf TCP test in the opposite
  direction) then the 1600-byte bins all get marked with both TX failures and
  _successive_ TX failures.
* Thus when it's time to TX a large packet, all the rates are marked as
  invalid.

This commit fixes the first problem - that the default rate selection was simply
choosing the highest MCS rate (and thus MCS15 was being used on a two stream NIC)
and so things like DHCP may take a few retransmits.

It also fixes the problem where all those MCS rates are slowly marked as invalid
by failures in small packets; the only rate left over is the base rate
(6mbit for 11a).

This doesn't fix a related problem - where subsequent TXes doesn't ever probe the
higher rates. Because the successive failures exist, those rates aren't ever
selected. pick_sample_rate() should be trying those after a while - 10 seconds by
default.

END