[Codel] [Cake] Proposing COBALT

Jonathan Morton chromatix99 at gmail.com
Thu May 26 08:33:54 EDT 2016

> On 24 May, 2016, at 18:52, Dave Täht <dave at taht.net> wrote:
> My last attempts with cake the way it was had it performing miserably at
> longer RTTs (try 50ms) vs codel or fq-codel - as in half the throughput
> achieved by codel, at that RTT.

There’s definitely something weird going on - as if the marks and drops reported by the stats are not actually occurring, except for the drops on queue overflow.

Testing 50:1 flows on 1:10 bandwidth, for example, the single flow is stuck below the aggregate throughput of the 50, suggesting strongly that its acks are not being thinned.  Cake used to be best-in-class on that very test.

I will investigate further.  But the solution may be to just perform the refactoring necessary to cleanly integrate COBALT, and eliminate subtle bugs by dint of simply sweeping away some unnecessarily gnarly code.  I think COBALT’s API is probably a lot easier to integrate into a complex qdisc than Codel’s.

 - Jonathan Morton

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