LRE-TL: an optimal multiprocessor algorithm for sporadic task sets with unconstrained deadlines

This article presents a detailed discussion of LRE-TL (Local Remaining Execution - TL-plane), an algorithm that schedules hard real-time periodic and sporadic task sets with unconstrained deadlines on identical multiprocessors. The algorithm builds upon important concepts such as the TL-plane construct used in the development of the LLREF algorithm (Largest Local Remaining Execution First). This article identifies of the fundamental TL-plane scheduling principles used in the construction of LLREF. These simple principles are examined, identifying methods of simplifying the algorithm and allowing it to handle a more general task model. For example, we identify the principle that total local utilization can never increase within any TL-plane as long as a minimal number of tasks are executing. This observation leads to a straightforward approach for scheduling task arrivals within a TL-plane. In this manner LRE-TL can schedule sporadic tasks and tasks with unconstrained deadlines. Like ...

• Type: Journal
• Year: 2010
• Where: RTS
• Authors: Shelby Funk
• Keywords: Algorithm, RTS 2010, Task Sets, Unconstrained Deadlines