K 10
svn:author
V 6
adrian
K 8
svn:date
V 27
2011-09-05T15:21:18.574378Z
K 7
svn:log
V 1330
As a temporary workaround, treat MCS error rates 5% higher than
the best rate as "ok" when picking a best rate.

This is all a hack to avoid having to implement the "correct"
solution, whatever that is. For example, minstrel calculates
a predicted A-MPDU throughput value based on the
average A-MPDU sub-frame count and per-rate TX success probability.

This, along with lowering sample_stats to 2 from 10 (ie, spend 2%
of TX time trying to sample alternate rates) seems to keep my TCP
TX mostly stable at around 120-130mbit for my testing.

TODO:

* The EWMA doesn't raise quickly enough and seems a bit wrong, eg:

[ 0 MCS: 250]      329:329      (100%) (EWMA  63.6%) T       22 F    0 avg   407 last 19144

.. how'd the EWMA come out to be 63% given a 100% success rate overall?
It made an incorrect judgement early on and hasn't yet had enough time
to correct it.

The sampling of other MCS rates is also not optimal - it shouldn't try
sampling all of them during the sample interval. Instead, come up with
a more intelligent way of picking the MCS rates to sample.

Finally, comparing MCS rates by number is incorrect. This really should
compare the per-rate throughput value, as higher MCS rate != higher
throughput.

But, as said above, this is "good enough" for local testing.
It shouldn't be merged into -HEAD like this.

END