Deficit round robin

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Deficit round robin (DRR)[1], also deficit weighted round robin (DWRR), is a modified weighted round robin scheduling discipline. DRR was proposed by M. Shreedhar and G. Varghese in 1995. It can handle packets of variable size without knowing their mean size. A maximum packet size number is subtracted from the packet length, and packets that exceed that number are held back until the next visit of the scheduler.

WRR serves every nonempty queue whereas DRR serves packets at the head of every nonempty queue which deficit counter is greater than the packet's size. If it is lower then deficit counter is increased by some given value called quantum. Deficit counter is decreased by the size of packets being served.

Compared with Fair queueing (FQ) scheduler that has complexity of O(log(n)) (n is the number of active flows), the complexity of DRR is O(1).

[edit] See also

[edit] References

  1. ^ Shreedhar, M.; Varghese,G. (October 1995). "Efficient fair queueing using deficit round robin". ACM SIGCOMM Computer Communication Review 25 (4). ISSN 0146-4833. 

[edit] External links


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Efficient fair queueing using deficit round robin Source Applications, Technologies, Architectures, and Protocols for Computer Communication archive Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication table of contents Cambridge, Massachusetts, United States Year of Publication: 1995 ISSN:0146-4833 Authors M. Shreedhar Microsoft Corporation George Varghese Washington University in St. Louis. Sponsor SIGCOMM: ACM Special Interest Group on Data Communication Publisher ACM Press New York, NY, USA

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