Approximation of Generalized Processor Sharing With Interleaved Stratified Timer Wheels

Abstract

This paper presents Interleaved Stratified Timer Wheels as a novel priority queue data structure for traffic shaping and scheduling in packet-switched networks. The data structure is used to construct an efficient packet approximation of general processor sharing (GPS). This scheduler is the first of its kind by combining all desirable properties without any residual catch. In contrast to previous work, the scheduler presented here has constant and near-optimal delay and fairness properties, and can be implemented with O(1) algorithmic complexity, and has a low absolute execution overhead. The paper presents the priority queue data structure and the basic scheduling algorithm, along with several versions with different cost-performance trade-offs. A generalized analytical model for rate-controlled rounded time-stamp schedulers is developed and used to assess the scheduling properties of the different scheduler versions.