Dear list,
I am currently trying to tune my R52n ath9k minipci card for maximum 
performance in a \
high interference city environment. Mode is 802.11n in the 5 GHz band.

What I see is better download compared to an R52 ath5k in 802.11a mode, but 
worse \
upload. I suspect either that the 802.11n modulation is less robust to noise OR 
that \
AMSDU aggregation is in use and is worsening resiliency to interference. See 
this \
monitoring screenshot: https://pasteboard.co/o8ykSMG.png The first part is 
802.11a, \
the second is 802.11n, and the third was obtained by limiting the uplink to 
legacy \
rates by:

iw dev wlan0 set bitrates legacy-5 6 9 12 18 ht-mcs-5

The problem: Unfortunately, the result of that is that only the 6 Mb/s rate is 
used. \
When I allow any ht-mcs-5 rate, none of the legacy rates is ever selected and 
the \
throughput is worse. It seems that the wandering minstrel algorithm is failing. 
The \
other side is a Mikrotik router and it freely mixes legacy and mcs rates to get 
\
optimal throughput, the Linux driver does not. 1. How would I debug this? Last 
time I \
did it in Madwifi, minstrel had some debug stats in procfs. 2. How to find out 
if \
AMSDU aggregation is in use and to disable it to see if that is the thing 
hurting \
performance?

The kernel version is 4.9.0 from Debian.

Thanks for your insights, Tomas Vondra

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