[Bloat] Bufferbloat Paper

[Toke Høiland-Jørgensen]

Stephen Hemminger <shemminger at vyatta.com>
writes:

> The tone of the paper is a bit of "if academics don't analyze it to
> death it must not exist". The facts are interesting, but the
> interpretation ignores the human element. If human's perceive delay
> "Daddy the Internet is slow", then they will change their behavior to
> avoid the problem: "it hurts when I download, so I will do it later".

Well severe latency spikes caused by bufferbloat are relatively
transient in nature. If connections were constantly severely bloated the
internet would be unusable and the problem would probably (hopefully?)
have been spotted and fixed long ago. As far as I can tell from their
graphs, ~5% of connections to "residential" hosts exhibit added delays
of >=400 milliseconds, a delay that is certainly noticeable and would
make interactive applications (gaming, voip etc) pretty much unusable.

Now, I may be jumping to conclusions here, but I couldn't find anything
about how their samples were distributed. However, assuming the worst,
if these are 5% of all connections to all peers, each peer will have a
latency spike of at least 400 milliseconds for one second every 20
seconds (on average). Which is certainly enough to make a phone call
choppy, or get you killed in a fast-paced FPS.

It would be interesting if a large-scale test like this could flush out
how big a percentage of hosts do occasionally experience bufferbloat,
and how many never do.

-Toke

-- 
Toke Høiland-Jørgensen
toke at toke.dk
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