low ath speed on 8.0-RC1

[Sam Leffler]

Denis Shaposhnikov wrote:
> Hello,
> 
> On Thu, 24 Sep 2009 19:46:41 -0700
> Sam Leffler <sam at freebsd.org> wrote:
> 
>>> May be do you know why I'm getting normal speed (2Mb/s) for some
>>> time after using "ifconfig bssid ..." command only?
>> When you set the bssid you reset the state of the tx rate control code
>> and that probably resets the tx rate to 24M.
> 
> Does it possible to disable tx rate control and lock wlan0 on
> OFDM/54Mbps? Think it isn't right tha I have only 900K of transfer speed
> without using of bssid command.

The bssid cmd is unrelated to your low tx rate; this is a byproduct of
(apparent) poor communication conditions.  All the cmd does is reset
state so the tx rate is yanked back to 24M from which it falls again to
where the rate control code believes is the right value.

For setting a fixed tx rate man ifconfig.  If you want to explore look
at enabling tx rate control msgs with

wlandebug rate

and/or look at sysctl dev.ath.0.sample_stats=-1.

	Sam