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Message-ID: <1319018802.31281.YahooMailNeo@web161205.mail.bf1.yahoo.com> (sfid-20111019_121314_568298_E48C9181)
Date: Wed, 19 Oct 2011 03:06:42 -0700 (PDT)
From: Joerg Pommnitz <pommnitz@yahoo.com>
Reply-To: Joerg Pommnitz <pommnitz@yahoo.com>
Subject: Re: [ath5k-devel] Performance regression between Madwifi/net80211 and ath5k/mac80211
To: Bob Copeland <me@bobcopeland.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"ath5k-devel@lists.ath5k.org" <ath5k-devel@lists.ath5k.org>
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Bob,
real world work interfered back in June but now I have a few more data points.
I made a cross test with ath5k on Fedora 2.6.40 (e.g. 3.0) and Madwifi-0.9.4 on
2.6.23. The interesting observation is, that the ath5k bottleneck seems to be
on the transmission end, e.g if the iperf client is attached to ath5k, the
performance is consistently lower.

Here is a table:
ath5k-ath5k???? = iperf server attached to ath5k, iperf client attached to ath5k
madwifi-ath5k?? = iperf server attached to madwifi, iperf client attached to ath5k
ath5k-madwifi?? = iperf server attached to ath5k, iperf client attached to madwifi
madwifi-madwifi = iperf server attached to madwifi, iperf client attached to madwifi

Note that on iperf the server is the traffic sink (and the measurement point) and
the client is the traffic source. Measured traffic was UDP as generated by
iperf -c <ip of server> -u -b 54M -t 15

The test setup was as followed:
* 59db attenuation between the two boxes (calibrated HF cable)
* Frequency 5200MHz (eg. 802.11a channel 40)
* txpower 10dBm on both sides
* ANI disabled on Madwifi

*SLOW*??? ? *SLOW*??? ??? ? *FAST*??? ??? ? *FAST*
ath5k-ath5k madwifi-ath5k?? ath5k-madwifi?? madwifi-madwifi
27553680????27553680??? ??? 7426440??? ???? 33998160
28082880??? 28135800??? ??? 24866520??? ??? 33851160
28212240??? 28212240??? ??? 32281200??? ??? 33615960
28323960??? 28112280??? ??? 33033840??? ??? 34027560
28300440??? 28259280??? ??? 32363520??? ??? 34303920
28088760??? 28276920??? ??? 34739040??? ??? 34021680
28112280??? 28212240??? ??? 34874280??? ??? 34415640
28247520??? 28088760??? ??? 34298040??? ??? 33886440
28247520??? 28235760??? ??? 34004040??? ??? 34292160
28176960??? 28141680??? ??? 34944840??? ??? 34409760
27930000??? 28224000??? ??? 35015400??? ??? 34174560
28206360??? 28159320??? ??? 35085960??? ??? 34403880
28135800??? 28082880??? ??? 33574800??? ??? 33951120
28135800??? 28041720??? ??? 34986000??? ??? 34045200
28147560??? 27965280??? ??? 35133000??? ??? 34174560

I will run with tcpdump on a monitoring interface for the combination
ath5k sender and madwifi sender shortly. Where should I capture the trace?

-- 
Regards
Joerg


----- Urspr?ngliche Message -----
> Von: Bob Copeland <me@bobcopeland.com>
> An: Joerg Pommnitz <pommnitz@yahoo.com>
> Cc: linux-wireless@vger.kernel.org; ath5k-devel@lists.ath5k.org
> Gesendet: 13:02 Donnerstag, 30.Juni 2011
> Betreff: Re: [ath5k-devel] Performance regression between Madwifi/net80211 and ath5k/mac80211
>
> On Wed, Jun 22, 2011 at 11:07 AM, Joerg Pommnitz <pommnitz@yahoo.com>
> wrote:
>>>? I guess you'll? need more help from the HW people here.
>>
>>? Bob, Bruno, Felix, Luis, Nick: Do you read?
>
> I guess I would be interested to know if there are any obvious
> differences in the streams. E.g. taking a monitor mode capture
> near the receiver should show whether the received power is similar,
> whether the # of retransmissions is significantly higher in ath5k
> vs madwifi, whether packets are sent at the same bitrates, if there
> are any pauses where ath5k doesn't seem to be doing anything, etc.
>
> Would it be possible to do a few captures with your setup?
> --
> Bob Copeland %% www.bobcopeland.com
>