Scheduling and priority mapping for static real-time middleware

This paper presents a middleware real-time scheduling technique for static, distributed, real-time applications. The technique uses global deadline mo notonic priority assignment to clients and the Distributed Priority Ceiling protocol to provide concurrency control and priorities for server executio n. The paper presents a new algorithm for mapping the potentially large num ber of unique global priorities required by this scheduling technique to th e restricted set of priorities provided by commercial real-time operating s ystems. This algorithm is called Lowest Overlap First Priority Mapping; we prove that it is optimal among direct priority mapping algorithms. This pap er also presents the implementation of these real-time middleware schedulin g techniques in a Scheduling Service that meets the interface proposed for such a service in the Real-Time CORBA 1.0 standard. Our prototype Schedulin g Service is integrated with the commercial PERTS tool that provides schedu lability analysis and automated generation of global and local priorities f or clients and servers.