iwn: Intel Centrino 6205 bad 11n performance

[Johannes Dieterich]

Dear Adrian

thanks a lot for the suggestion! Removing ht indeed improves the throughput
to 1.7 MB/s. Still far from the maximum of my uplink but sufficient for the
time being and much improved.

Concerning the non-existing maintainer: does it in this case even make
sense to file a PR?

Given how common the Intel WLAN NICs (unfortunately) are and how some
notebooks have white lists making a change to e.g. ath impossible, it is a
real bummer that nobody maintains it. Thanks for your work on ath, btw,
those NICs are working great nowadays!

Thanks again for the help!

Johannes


On Wed, Aug 20, 2014 at 12:30 AM, Adrian Chadd <adrian at freebsd.org> wrote:

> Hi,
>
> You can try disabling 11n (ifconfig -ht) but besides that, there's no
> real iwn maintainer or anyone who wants to get really nitty gritty
> into what the driver is doing. So until that happens, I think we're
> short of luck. :(
>
>
> -a
>
>
> On 19 August 2014 12:53, Johannes Dieterich <dieterich.joh at gmail.com>
> wrote:
> > Dear all,
> >
> > I have a Intel Centrino Advanced-N 6205 WLAN NIC in my Thinkpad using
> iwn.
> >
> > iwn0 at pci0:3:0:0:    class=0x028000 card=0x13118086 chip=0x00858086
> rev=0x34
> > hdr=0x00
> >     vendor     = 'Intel Corporation'
> >     device     = 'Centrino Advanced-N 6205 [Taylor Peak]'
> >     class      = network
> >
> > Unfortunately, I only get a rather bad speed using CURRENT (r270098) out
> of
> > the chip. It is connected to an 11n (on the 2.4 GHz band) network:
> >
> > wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu
> 1500
> >     nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> >     media: IEEE 802.11 Wireless Ethernet MCS mode 11ng
> >     status: associated
> >     ssid XXXXX channel 4 (2427 MHz 11g ht/20) bssid XXXXXXXXXX
> >     country US authmode WPA2/802.11i privacy ON deftxkey UNDEF
> >     TKIP 2:128-bit txpower 15 bmiss 10 scanvalid 60 bgscan bgscanintvl
> 300
> >     bgscanidle 250 roam:rssi 7 roam:rate 64 protmode CTS ampdulimit 64k
> >     ampdudensity 8 -amsdutx amsdurx shortgi wme roaming MANUAL
> >
> > I get a maximum of 900 KB/s of throughput (both in/out, approximated by
> > copying a large file using scp), within the network and to the outside
> > world. Running SuSE Linux on the notebook allows me to easily saturate my
> > uplink at > 3MB/s, didn't then further check within the network. I get no
> > log messages on FBSD from iwn and I am not located in a particularly
> noisy
> > neighborhood.
> >
> > The only performance issue I can find with this chip is one old report on
> > Ubuntu (http://ubuntuforums.org/showthread.php?t=1949571), where the 11n
> > seemed to be the culprit in the driver/firmware. Could this be an issue
> for
> > us as well (firmware problem?)?
> >
> > As my workhorse is FreeBSD, I'd love to fix this issue. How can I further
> > debug this issue and/or provide more data? I know that the status of iwn
> in
> > FBSD is difficult ATM but maybe there is hope?
> >
> > Best
> >
> > Johannes
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