Re: Packet throughput (and those iperf data rate) with mac80211/ath9k is 20% worse than net80211/madwifi

[Dave Taht <dave.taht@gmail.com>]

On Mon, Jan 30, 2017 at 8:17 AM, Toke H=C3=B8iland-J=C3=B8rgensen <toke@tok=
e.dk> wrote:
> Klaus Kinski <jpo234-1ViLX0X+lBKELgA04lAiVw@public.gmane.org> writes:
>
>> Hello all,
>>
>> this is a blast from the past, but something that still bothers me.
>> I have two systems with Atheros/QCA cards:
>>
>> System A:
>>   OS and driver: Linux 3.18.36 with last Madwifi/sample code from trunk
>>
>>   WLAN card: AR5413 (Senao EMP-8602 PLUS-S)
>>
>> System B:
>>   OS and driver: Linux 3.18.36 with mac80211/minstrel and ath9k from bac=
kports-4.2
>>
>>   WLAN card: AR9280 (Compex WLE200NX)
>>
>> While doing the performance measurements both systems are connected to a=
 reference system
>>
>> with a HF cable, so there should be no outside influences.
>>
>> Both systems are running in 802.11a mode on channel 40.
>> The following table shows 802.11 data packets sent from system A and B g=
enerated by
>>
>> iperf in UDP mode over a 2s interval:
>
> What version of iperf, and configured to which rate? Some versions of
> iperf will send its traffic in very large bursts (see
> http://burntchrome.blogspot.se/2016/09/iperf3-and-microbursts.html?m=3D1)
> which could cause the queue inside ath9k to overflow (it is only 123
> packets pre-4.10).
>
> Did you try the latest mac80211/ath9k from 4.10? The queueing structure
> changed dramatically, which would impact this, at least if it's a queue
> overflow problem...

Packet captures would be helpful. Aircaps, if possible, also.

> -Toke



--=20
Dave T=C3=A4ht
Let's go make home routers and wifi faster! With better software!
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