[Cake] A few puzzling Cake results

Jonathan Morton chromatix99 at gmail.com
Tue Apr 17 10:03:12 EDT 2018

> On 17 Apr, 2018, at 12:42 pm, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> - The TCP RTT of the 32 flows is *way* higher for Cake. FQ-CoDel
>  controls TCP flow latency to around 65 ms, while for Cake it is all
>  the way up around the 180ms mark. Is the Codel version in Cake too
>  lenient, or what is going on here?

A recent change was to increase the target dynamically so that at least 4 MTUs per flow could fit in each queue without AQM activity.  That should improve throughput in high-contention scenarios, but it does come at the expense of intra-flow latency when it's relevant.

To see whether Diffserv actually prioritises correctly, you'll need to increase the number of bulk flows beyond the point where the VoIP flow no longer receives the bandwidth it needs purely from its fair share of the link.

 - Jonathan Morton

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