Subject: Re: Slow wi0 ftp transfers after kernel upgrade?
To: None <>
From: David Young <>
List: tech-net
Date: 03/01/2003 22:39:59
On Sun, Mar 02, 2003 at 12:33:39PM +1100, Paul Ripke wrote:
> I upgraded my kernel (for a variety of reasons) from 20030128 sources 
> up to 20030218, then
> after discovering the problem, up to 20030301, in case it had been 
> fixed.

Between 1/28 and 2/18, it does not look to me like anything changed
in wi(4).

> BTW: I've also noticed that my wi0 appears to be asymmetric... I get 
> approx 180 KB/s in one
> direction (NetBSD sending) and 500+ KB/s in the other.

In Host AP mode, NetBSD does the WEP encryption for transmission.
Perhaps that explains the asymmetry?

> tcpdump shows 0.6 - 1.0 second pauses, which looks like a timeout to 
> me. is
> the laptop, is the NetBSD box.

I do not know what could explain the pauses. Does wi0 log anything during
the pauses? You might get to the bottom of this by running in debugging
mode. Add IEEE80211_DEBUG and WI_DEBUG to your kernel config and use
ddb to bump up wi_debug and ieee80211_debug.

> 2 Mbit sounds about right. What happened to DS11?

I don't know why it has adapted to 2Mb/s.

BTW, in Host AP mode, the Prism firmware accepts per-packet TX rates, but
wi(4) does not take advantage. It would be nice if somebody would program
a rate algorithm for the IEEE802.11 framework, especially since this will
be necessary for the "dumber" 802.11 cards coming to market. Lucent has
a technical report on rate adaptation which I can scare up for anybody
who is interested.


David Young             OJC Technologies      Engineering from the Right Brain
                        Urbana, IL * (217) 278-3933