[altq:1682] Re: Unstable cbq on Openbsd box

[Danny Kjærgaard <turtle@paradis.dk>]

It was the red.

but how can i configure it ? is there a doc/howto anywhre ?

thanks
----- Original Message -----
From: "Nicolas Christin" <nicolas@cs.virginia.edu>
To: "Danny Kjærgaard" <turtle@paradis.dk>
Cc: <altq@csl.sony.co.jp>
Sent: Thursday, October 17, 2002 10:21 PM
Subject: [altq:1681] Re: Unstable cbq on Openbsd box


On Thu, 17 Oct 2002, Danny Kjærgaard wrote:

> I measure the flow with the FTP client.

Generally, an FTP client doesn't provide a good estimate... Still:

> here's the output of altqstat:
[snip]
>      RED q_avg:5.68 xmit:6482 (forced:0 early:55 marked:0)
>         QCount: 7,      (qmax: 60)
>         AvgIdle: -55 [us],      (maxidle: 5737 minidle: -46875 [us])
[snip]

Try removing RED. Unless you really want a very low delay, it's
obviously misconfigured, the queue length is too low compared to the
maximum queue length, which could be the cause of unnecessary packet
drops ultimately resulting in throughput degradation. Yes, you do only
drop <1% of packets, but if - for some reason - all the drops happen
within a short time interval, that would explain it.

I'll look more carefully into this later, but see if things improve when
you don't use RED. Please provide a longer altqstat trace (~3-4
seconds around the time of the problem suffice), also, just one
iteration isn't good enough.

--
Nicolas Christin
Ph.D. Candidate, University of Virginia, Computer Science
http://www.cs.virginia.edu/~nicolas