Object technologies and real-time scheduling

Abstract

Any object-based real-time system gives rise to real-time scheduling issues not easily solved by use of standard scheduling methods, including: (1) the invocation of an object's method may imply the need for online schedulability analysis for the thread(s) able to execute method code, (2) parallelism internal to objects may result in the need to schedule multiple threads and target processors simultaneously, and (3) methods that invoke other methods as part of their execution give rise to hierarchically composed groups of to-be-scheduled real-time threads. The Rapid scheduler presented in this paper addresses such dynamic object-based real-time systems for target machines comprised of both multi- and uniprocessor machines. To address the variety of needs of object-based real-time systems, Rapid is 1) configurable to the target multiprocessor architecture, 2) dynamically re-configurable to changes in application requirements, 3) efficient in terms of processor utilization, and 4) effective in producing high quality schedules. Rapid's current implementation addresses hard deadline application, with future work concerning alternative formulations of timing constraints.