On-line admission control and packet scheduling with interleaving

This paper presents a comprehensive study of the effect of job interleaving by preemption on the throughput of a single server where requests arrive with a given processing time and slack. The problem is to decide which requests to serve so as to maximize the server's utilization. This simple model captures many situations, both at the application (e.g., delivery of video) as well as at the network/transmission levels (e.g., scheduling of packets from input to output interface of a switch). The problem is on-line in nature, and thus we use competitive analysis for measuring the performance of our scheduling algorithms. We consider two modes of operation - with and without commitment - and derive upper and lower bounds for each case. Since competitive analysis is based on the worst-case scenario, the average-case performance of the algorithms is also examined by a simulation study.