[Cake] Modification of DRR with deficit saving

[Toke Høiland-Jørgensen]

This popped up in my Google Scholar notifications:

https://atlas.informatik.uni-tuebingen.de/~menth/papers/Menth18b.pdf

Basically, they are proposing to permit a queue to accumulate a larger
deficit while empty to allow light users to achieve the same throughput
as heavy users (users being an endpoint with potentially multiple
flows).

Not sure how useful this really is, but it's somewhat related to Cake's
src/dst user fairness feature, so may be of interest.

-Toke