Re: [WIP] mac80211: AMPDU rx reorder timeout timer

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2010-07-27 at 08:20 +0200, Christian Lamparter wrote:
> This (rather _unfinished_ :-D ) patch adds a timer which
> if trigger schedules the automatic release of all expired
> A-MPDU frames. This implementation has the advantage that
> all queued-up MPDU will now arrive in the network core
> within a timely manner.
> 
> In my "experiments", the patch helped to ironed out the
> sudden throughput drops that have been _killing_ my
> average tcp performance ever since I can remember.

But why is your BA session so damaged to start with? This is not a
normal situtation!

> But there is a catch: The logs will quickly fill up with:
> "release an RX reorder frame due to timeout on earlier frames".
> and the package loss will goes through the roof...
> 
> Now, I can think of several reasons why this could happen:
> 	1. we don't wait long enough for the HT peer to
> 		finish their _retry_ procedure?
> 
> 	2. previously - when the stream simply _stopped_ - we had
> 		to wait until the tcp retry kick in again. So we had
> 		some "silent" periods and therefore less noise from
> 		the reordering code?
> 
> 	3. ->bugs<- but where are they?

I'm having a hard time understanding this patch, can you split out the
no-op code reorg parts or explain what it does?

johannes