The Research Of EDZL Real-time Scheduling Algorithm For Multiprocessor Systems

Real-time system is not only to ensure the correctness of logical task to run, but also to ensure that within a limited time to complete the assigned task. Otherwise, the real-time tasks to miss the deadline will result in serious consequences.Real-time scheduling algorithm in a real-time system is one of the core subjects. With the rapid development of computer technology, the application of multiprocessor real-time systems has become increasingly widespread. Real-time scheduling in multiprocessor systems more and more cause for concern. EDF (Earliest Deadline First) scheduling algorithm and LLF (Least Laxity First) scheduling algorithm have proven to be a single-processor systems optimal scheduling algorithm. However, in multiprocessor systems, this optimality fails, EDZL (Earliest Deadline Zero Laxity) scheduling algorithm is superior to the two algorithms.This paper starts from EDF scheduling model, and analyzes the optimality of EDF algorithm on a single processor system, but EDF algorithm in a multiprocessor system is not optimal. EDZL scheduling algorithm for multiprocessor system is introduced in this paper. EDZL algorithm is a improved algorithm of EDF algorithm.This paper studies EDZL scheduling algorithm more depth, including the properties of the EDZL algorithm, and comparing the EDF scheduling algorithm and EDZL scheduling algorithm. That EDZL Scheduling algorithm dominate EDF scheduling algorithm has proved.The schedulability of real-time scheduling algorithm is a measure of the reliability of a real-time system. EDZL algorithm is a job level dynamic priority algorithm, and the analysis with the conventional utilization method is difficult to determine schedulability of EDZL algorithm. This paper analyzes a job can tolerate the lower bound of interference, and other tasks on the job may have the upper bound of interference, by comparing these two bounds, proved sufficient conditions to the schedulability.For real-time system engineering design, a program is written for the schedulability test of EDZL scheduling algorithm. This program can test the task set in the real-time system, ensuring the reliability of the system used EDZL scheduling algorithms.