Research On Mixed-criticality Real-time Scheduling Algorithm

In modern safety-critical real-time embedded systems(such as automotive electronic systems,avionics systems),along with the increasing number of applications,the structure of the systems are more and more complex,considering performance,cost savings,functional diversification,safety and reliability,an increasingly important trend of these systems is the integration of componets with different levels of criticality onto a common hardware platform.In such a "mixed-criticality" system,different task with different criticality may interference and influence each other which would bring a lot of new scheduling problems.There are a lot of deficiencies exist in the current research on mixedcriticality system scheduling area(such as inadequate scheduling model,inflexible system design).In order to solve these problems,we use a method which is the combination of theory and practice to study the mixed-criticality real-time scheduling algorithm.The main research works are as follows:Firstly,taking into account that the most existing mixed-criticality scheduling algorithms only consider the case of dual-criticality systems,we introduce a new response time analysis algorithm which support for multi-criticality systems.Secondly,considering the current mixed-criticality scheduling algorithm will abandon the relatively low-critical tasks immediately in order to ensure the higher critical task execution when the system criticality increases,it is too negative,this paper based on the elastic scheduling model,proposed a elastic scheduling algorithm for mixed-criticality systems,handling the low-critical tasks positively.Experiments show that the algorithm is significantly improving the number of acceptable tasks.Finally,the existing scheduling algorithms studies mostly based on simulation experiment platform,such experiment results are too idealistic and did not considering the real system overhead(such as task migration overhead,system scheduling overhead).Therefore,this paper based on detailed analysis of the scheduling overhead,proposed an overhead-aware scheduling model,and implement the experiment platform on the Linux operating system,the scheduling algorithm is improved through the feedback of scheduling algorithm in the actual running,the overhead-aware experiment platform erected the bridges between theory and practice,which greatly enhance the practicability of the scheduling algorithm.