Research For Scheduling Algorithm About Multi-type Real-time Task Set On Multiprocessor System

With the rapid development of computer technology,intelligent systems are widely used in industrial production,national defense,space exploration and other fields and become more complex,which show a trend of multiple processors to work together.Multi-type real-time task scheduling on the multiprocessor is one of key technology of complex intelligent systems,related to the industrial,defense and safety of human life and property,and thus attracted the attention of domestic and foreign experts.The current combination scheduling algorithm about multiple types of real-time task on multiprocessors,although considers the characteristics of the various tasks to a certain extent,but there is no better coordination between the various tasks.For the shortcomings of the current combination algorithm,we use two combination scheduling algorithm to schedule multi-type real-time task sets on the multiprocessor,to improve the responsiveness of the soft real-time tasks and the scheduling success rate of sporadic real-time tasks respectively on the premise of meeting the deadline of periodic hard real-time tasks.The main work is as follows.For the scheduling problem that multi-type real-time task set which consists of periodic hard real-time tasks,aperiodic soft real-time tasks and non real-time tasks on the homogeneous multiprocessor,while the current combination algorithms consider insufficiently the relationship between different types of real-time task,fpEDF(combined fixed priority algorithm and EDF algorithm)algorithm and RCSD(resource-centric with slack defragmentation)algorithm schedule multiple types of real-time task set in this paper.RCSD algorithm considers the characteristics that a certain slack time between the two actual scheduling periodic tasks,and properly adjust them to better schedule aperiodic tasks.The proposed combination algorithm ensures the periodic real-time tasks to meet the deadline,and improves effectively the responsiveness of aperiodic tasks.For the scheduling problems that multi-type real-time task set which consists of periodic hard real-time tasks,sporadic hard real-time tasks and aperiodic soft real-time tasks on heterogeneous multi-processor,the current combination algorithms have deficiencies that allowing processor to premature use.This paper uses UEDF algorithm and TCSD(task-centric with slack defragmentation)algorithm to schedule this type of multi-type real-time task set.UEDF algorithm schedules periodic real-time tasks to execute as less processors as possible on the premise of ensuring periodic real-time tasks to meet the deadline to set aside spare processor resources in order to facilitate the execution of sporadic task arriving in future;then take the advantages of TCSD algorithm to improve effectively the scheduling success rate of sporadic real-time tasks.The experiments in this paper verify the success rate of the two combination scheduling algorithms to schedule different types of real-time task sets on the homogeneous multiprocessor or heterogeneous multiprocessor.Based on the characteristics of different types of real-time tasks to generate different combination algorithms to schedule multiple types of real-time tasks,it verifies the effectiveness of the combination scheduling algorithm in paper,which is compared with various current scheduling algorithms.