When Heavy-Tailed and Light-Tailed Flows Compete: The Response Time Tail Under Generalized Max-Weight Scheduling
This paper focuses on the design and analysis of scheduling policies for multi-class queues, such as those found in wireless networks and high-speed switches. In this context, we study the response time tail under generalized max-weight policies in settings where the traffic flows are highly asymmetric. Specifically, we study an extreme setting with two traffic flows, one heavy-tailed, and one light-tailed. In this setting, we prove that classical max-weight scheduling, which is known to be throughput optimal, results in the light-tailed flow having heavy-tailed response times. However, we show that via a careful design of inter-queue scheduling policy (from the class of generalized max-weight policies) and intra-queue scheduling policies, it is possible to maintain throughput optimality, and guarantee light-tailed delays for the light-tailed flow, without affecting the response time tail for the heavy-tailed flow.
© 2013 IEEE. Date of Conference: 14-19 April 2013. Jayakrishnan Nair and Adam Wierman acknowledge the support of the NSF through grant CNS 0846025 and NetSE grant CNS 0911041, the ARO through MURI grant W911NF-08-1-0233, and Bell Labs, Alcatel-Lucent. Krishna Jagannathan's work was funded in part by ARO MURI grant W911NF-08-1-0238 and the Indo UK Advanced Technology Center (IUATC).