This paper is concerned with a scheduling problem that occurs in service systems, where customers are classified as `ordinary' and `special'. Ordinary customers can be served on any service facility, while special customers can be served only on the flexible service facilities. Customers arrive dynamically over time and their needs become known upon arrival. We assume any service, once started, will be carried out to its completion. In this paper, we study the worst-case performance of service policies used in practice. In particular, we evaluate three classes of service policies: policies with priority, policies without priority, and their combinations. We obtain tight worst-case performance bounds for all service policies considered.
Journal of Scheduling; DOI: 10.1007/s10951-008-0075-7