| As real-time devices are gradually applied to various scenarios,the types and application areas of real-time systems have also been continuously enriched and expanded.Sporadic real-time systems are real-time systems with occasional tasks in periodic tasks,and are commonly used in industrial control,unmanned driving,and aerospace.In order to solve the problem of high resource consumption and poor performance of the scheduling consumption system in an accidental real-time system,an overload control strategy(MDTIC)suitable for sporadic real-time systems is proposed.MDTIC contains overload determination and overload handling in two parts.First,use the maximum steal time and the minimum and deferral time to judge the overload condition of the system,then use the inaccurate calculation and candidate solution table according to the result of the overload determination,and achieve the purpose of reducing the occasional real-time system overload by discarding some insignificant tasks.In order to verify the effectiveness and practicability of MDTIC control strategy,the occasional real-time system scheduling algorithm MIEDF based on MDTIC strategy,PID control and EDF scheduling algorithm was designed and implemented.PID control is a simple and efficient parameter control strategy.Because of the different operating environment and time of the system,it will cause the actual running time of the task in the scheduling algorithm to deviate from the expected running time in the system design process.Therefore,PID control strategy is added to strengthen The fault tolerance of the MIEDF scheduling algorithm.Through experiments,MDTIC strategy can not only accurately and quickly determine the system load conditions,according to the severity of overload adjustment to be scheduled task set,while reducing the system load to ensure that as many tasks as possible to run effectively,and thus ensure the system's work efficiency.In addition,the MDTIC overload control strategy can make up for the defects of the EDF algorithm in overload processing and effectively exert its superiority.Therefore,MIEDF can accumulate more mission value under overload conditions and have higher success rate of tasks than traditional scheduling algorithms and recent related improved scheduling algorithms. |
