Improved Smoothed Round Robin schedulers for high-speed packet networks

The Smoothed Round Robin (SRR) [7] packet scheduler is attractive for use in high-speed networks due to its very, low time complexity, but if is not suitable for real-time applications since it cannot provide tight delay bound. In this paper, we present two improved algorithms based on SRR, namely SRR+ 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.