[Bloat] [Cake] documentation review request and out of tree cake builds for openwrt/etc.

[Dave Taht]

On Thu, Apr 30, 2015 at 7:38 AM, Jonathan Morton <chromatix99 at gmail.com> wrote:
> It took me a while to get around to thinking about this, partly because my
> phone inexplicably refuses to believe snapon exists.

It has an old dnssec signed dns tree, using the isc dlv, which turned
out to somewhat break older versions of dnsmasq, if that helps any.
Dire need for some sysadmin help on bufferbloat.net, the cruft has accumulated.

> I have two possible explanations for these results. Maybe both apply to some
> extent.
>
> Dropping packets rather than marking them results in an increase in ack
> density in the reverse direction, because delayed acks get temporarily
> disabled. The strength of this effect depends on the BDP and the depth of
> delayed acks.

Hmm.

>
> Increasing the number of simultaneous flows might increase the CPU load of
> connection tracking for NAT. Are you shaping and doing NAT on the same box?
> I think this might be the basic reason for increased latency.

That particular setup (yurtlab) offloads the NAT to the cable modem.
The 110_11Mbit shaping was of course, done on the rangeley. It is
possible given the older kernel that perhaps I could be hitting the
same power mgmt issue that someone else here ran into earlier, or
merely the kernel is weird, or something new like xmit_more is messing
up life.

I returned to another location (gf) and tested 50mbit down/5mbit up
(cerowrt 3.10.50-1 in front of a live cablemodem, same two boxes
driving the test) up for much of the past 2 days, and on the same test
(rrul starting, then doing the dslreports test) observe expected
results, with the download having the normal brief spike, the upload
impact being nearly immeasurable, and the observed latency increase in
either direction, negligible.

http://snapon.lab.bufferbloat.net/~d/dslreports2/dslreports_vs_rrul_50_5mbit.png

verses the puzzling one:

http://snapon.lab.bufferbloat.net/~d/dsl/vsdslreports_at_the_sametime.png

So the next step for me is to get cake working in openwrt on hardware
fast enough to run at 110Mbit and returning to the yurtlab to try
it... but that won't be til sunday at best. Tho I almost got it built,
at least, last night. Still sorting through patches....





>
> - Jonathan Morton



-- 
Dave Täht
Open Networking needs **Open Source Hardware**

https://plus.google.com/u/0/+EricRaymond/posts/JqxCe2pFr67