Improvement to Quick Processor-Demand Analysis for EDF-Scheduled Real-Time Systems

Earliest Deadline First (EDF) is an optimal scheduling algorithm for uniprocessor real-time systems. Quick Processor-demand Analysis (QPA) provides efficient and exact schedulability tests for EDF scheduling with arbitrary relative deadline. In this paper, we propose Improved Quick Processor-demand Analysis (QPA*) which is based on QPA. By extensive experiments, we show that QPA* can significantly reduce the required calculations to perform an exact test for unschedulable systems. We prove that the computation time for testing schedulable systems is hardly affected. Hence the required calculations for general systems can be significantly decreased.