Predictable threads for dynamic, hard real-time environments

Next-generation, hard real-time systems will require new, flexible functionality and guaranteed, predictable performance. This paper describes the UMass Spring threads package, designed specifically for multiprocessing in dynamic, hard real-time environments. This package is unique because of its support for new thread semantics for real-time processing. Predictable creation and execution of threads is achieved because of an underlying predictable kernel, the UMass Spring kernel. Design decisions and lessons learned while implementing the threads package are presented. Measurements affirm the predictability of this implementation on a representative multiprocessor platform. The adoption of the threads package in the UMass Spring kernel results in additional performance improvements, which include reduced context switching overhead and reduced average-case memory access durations.