ath 802.11g throughput in 6.2-RELEASE

[Sam Leffler]

Kernel Jake wrote:
> Since upgrading to 6.2-RELEASE from 6.0-RC1, I have seen lower ath0
> network throughput than I had previously.  I can't remember exactly what
> speeds I had prior to 6.2, but they were definitely greater than 11
> Mbps, probably closer to 48 Mbps.

The current tx rate != throughput; please provide more specifics.

> 
> When I used my old 6.0-RC1 kernel config file with 6.2-RELEASE, it
> contained "device ath_rate_onoe", and the speed was between 1 and 5 Mbps
> .  I then noticed that the 6.2 ath man page listed "device
> ath_rate_sample", so I changed my config to use "sample" instead of
> "onoe", and now I get around 11 Mbps.  But it still isn't as fast as it
> used to be.  Nothing changed in my environment other than my client
> (meaning physical layout, wireless channel, wap firmware, etc).

The "sample" rate control algorithm is much better than onoe for most
uses.  However if you prefer onoe for some reason you can just use it.

> 
> WAP: D-Link WRT54G ver.4, Firmware version 4.71.1 Hyperwrt 2.1b1 +
> Thibor15c
> NIC: D-Link DWL-G520 Rev.B3
> 
> % uname -a
> FreeBSD canary 6.2-RELEASE-p3 FreeBSD 6.2-RELEASE-p3 #0: Mon May 14
> 22:14:35 CDT 2007     jake at canary:/usr/src/sys/i386/compile/CANARY  i386
> 
> % dmesg | grep ath
> ath_hal: 0.9.17.2 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413)
> ath0: <Atheros 5212> mem 0xeb000000-0xeb00ffff irq 17 at device 14.0 on
> pci0
> ath0: Ethernet address: 00:11:95:92:72:55
> ath0: mac 7.9 phy 4.5 radio 5.6
> 
> % ifconfig ath0
> ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>        inet 192.168.1.55 netmask 0xffffff00 broadcast 192.168.1.255
>        inet 192.168.1.54 netmask 0xffffffff broadcast 192.168.1.54
>        ether 00:11:95:92:72:55
>        media: IEEE 802.11 Wireless Ethernet autoselect mode 11g (DS/11Mbps)
>        status: associated
>        ssid yagi channel 2 bssid 00:14:bf:27:f1:bc
>        authmode WPA privacy ON deftxkey UNDEF TKIP 2:128-bit TKIP 3:128-bit
>        txpowmax 36 bmiss 7 protmode OFF burst roaming MANUAL bintval 100

Look at the athstats tool in src/tools/tools/ath/athstats; it can
usually provide the info to explain issues at the MAC layer (given
enough experience reading the stats).  In particular watch for bursts of
errors when using athstats 1 that might indicate interference on the
channel.

	Sam