Communicating shared resources: A model for distributed real-time systems

Richard Gerber, University of Pennsylvania


The timing behavior of a real-time system depends not only on delays due to process synchronization, but also on the availability of shared resources. Most current real-time models capture delays due to process synchronization; however, they abstract out resource-specific details by assuming idealistic operating environments. On the other hand, scheduling and resource allocation algorithms used for real-time systems ignore the effect of process synchronization except for simple precedence relations between processes. To bridge the gap between these two disciplines, we have developed a methodology called Communicating Shared Resources, or CSR. In this dissertation we describe our approach to the specification and verification of real-time systems. Application processes are specified in the CSR application language, which includes language constructs that are essential in real-time settings, such as timeouts, deadlines, periodic processes, interrupts and exception-handling. Then, a configuration schema is used to map the processes to system resources, and to specify the physical communication links between them. To analyze and execute the entire system, we automatically translate the result of the mapping into the CCSR process algebra. CCSR characterizes CSR's resource-based computation model by a priority-sensitive, operational semantics. To do this, we have formulated a natural treatment of preemption, which is based not only on priority, but also on resource utilization and inter-resource synchronization. The preemption ordering leads to a compositional proof system, which allows the syntactic manipulation of CCSR terms. Using this proof system, we perform the algebraic verification of our original real-time system.

Subject Area

Computer science

Recommended Citation

Gerber, Richard, "Communicating shared resources: A model for distributed real-time systems" (1991). Dissertations available from ProQuest. AAI9200337.