[Cake] [Codel] hard limit codel

Toke Høiland-Jørgensen toke at toke.dk
Thu Apr 16 07:50:53 EDT 2015

Rich Brown <richb.hanover at gmail.com> writes:

> Please don't fisk this. The paper is *way* too long to be worth a
> sentence-by-sentence refutation of every inaccuracy or outright
> wrong-headed understanding of Codel... :-)

I think this paragraph pretty much sums it up:

"Actually, the throughput of hard limit CoDel is signifi- cantly lower
than the original CoDel only when the RTT is large (500ms), the
bandwidth is high (64 Mbps) with only one TCP flow, in which case the
throughput is only 4.1 Mbps, 63% lower than that of the original CoDel.
Though it may seem to be a significant loss, we argue that it is
acceptable because even in the worst case, a bit rate of 4 Mbps is
sufficient to support today’s 720p videos. The link utilization is much
higher when either of the three conditions changes."

Surely, 4Mbps is enough for everybody?

I'll add, though, that I have seen the sentiment expressed here ("we
need to limit the max delay of CoDel") in other contexts. And, well,
delay spikes *is* a problem!


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