Improved Smoothed Round Robin Schedulers for High-Speed Packet Networks

The smoothed round robin (SRR) packet scheduler is attractive for use in high-speed networks due to its very low time complexity, but it is not suitable for realtime applications since it cannot provide tight delay bound. In this paper, we present two improved algorithms based on SRR, namely SRR^c and SRR^#, which are based on novel matrix transform techniques. By transforming the irregular Weight Matrix of SRR into triangular and diagonal ones, SRR⁺ and SRR^# are able to evenly interleave flows based on their reserved rates even in skewed weight distributions. SRR⁺ and SRR^# provide bounded delay, whereas are still of low space and time complexities and are simple to implement in high-speed networks. The properties of SRR⁺ and SRR^# are addressed in detail through analysis and simulations. SRR⁺ and SRR^#, together with SRR and the recently developed G-3 scheduler [9] form a full spectrum of schedulers that provide tradeoffs among delay, time complexity, and space complexity.