[Cerowrt-devel] increasing the *codel target for DSL at really low bandwidths

[Dave Taht]

I have struggled with really low bandwidths. Folk like fred have
really struggled with low bandwidths (to the point of switching to pie
on his workload, which has a 20ms target), and having got some
configuration info from maxime over free.fr (biggest ecn enabled
fq_codel'd deployment I know of), and finally having reasonable
confidence that the
htb to atm cell size compensation stuff is *fixed*...

I'd like to suggest to those with bandwidths under 5mbit try something
like this to calculate a larger target variable for *codel. (might
make sense on pie, too)

There are many significant variables at these speeds, not least of
which are fixed constants like iw10. It would not surprise me if we
needed to ramp up the curve even further below 1mbit, or double it
from what stands here. This curve is good down to almost 128kbit
before it overshoots the interval, which regardless needs to be
modified too...

suggestions? Who here runs at under a mbit on any form of technology?

#!/bin/sh
# 13000000us for 1 1500 byte packet at 1kbit.

bw_up=$1

delay=$((13500000/($bw_up)))
[ "$delay" -lt 5000 ] && delay=5000

echo target ${delay}us


-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html