RE: help: 802.11s bad performance with 802.11n enabled

["Paul Stoaks" <paul@foresight-mands.com>]

What kind of traffic are you pushing through (packet sizes?)  Are they fixed
size, fixed rate, or ...?

Paul


-----Original Message-----
From: linux-wireless-owner@vger.kernel.org
[mailto:linux-wireless-owner@vger.kernel.org] On Behalf Of Georgiewskiy
Yuriy
Sent: Monday, December 03, 2012 7:44 AM
To: Chaoxing Lin
Cc: linux-wireless@vger.kernel.org
Subject: RE: help: 802.11s bad performance with 802.11n enabled

On 2012-12-03 14:56 -0000, Chaoxing Lin wrote Georgiewskiy Yuriy:

CL>CL>For experiment, I changed ath9k driver to disable 802.11n packet
aggregation. The network becomes much better.
CL>CL>It's as stable as running 802.11a only mode.
CL>CL>So it seems that the aggregation plays a big role in in-stability of
802.11s network with 802.11n.
CL>CL>Any one has any idea why?
CL>
CL>Can you post a patch? i want test this too.
CL>
CL>The change is easy
CL>In ath9k/init.c
CL>Function ath9k_set_hw_capab()
CL>Replace below
CL>    if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_HT)
CL>         hw->flags |= IEEE80211_HW_AMPDU_AGGREGATION; with
CL>	hw->flags &= ~IEEE80211_HW_AMPDU_AGGREGATION;

On first look in my case disabled aggregation reduces packet loss, link is
more reliable, but it's also drop throughput to 15-20 Mbits/sec from about
~50 with aggregation enabled.

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