Improvement Research Of Scheduling Analysis Tool For Distributed Real-Time System

With the rapid development of information technology, computer systems which integrated networking and embedded features have been extensively researched, distributed real-time system appears. Because of the expansion of system scale with functional and non-functional properties, developers begin to focus on the higher level of abstraction rather than implementation details to consider the structural problems in software design stage. So model-based methods have been gradually used.Model-based method is treated as a natural expressionon by the developer's different professional knowledge and development demands of the objective world. In order to measure the performance of the system, early assessment of the model would reduce unnecessary risks of the loss of manpower and resources in the future. By verifying the properties of the system model, developers could receive the feedback directly, then make further efforts to optimize the model, thence improve the software system reliability, correctness and maintainability. After modified the model, the work can turn to other system development operations like automatic code generation, software testing, till the final completion of real-time reliable embedded systems in a distributed architecture.From the emergence of embedded systems, the attribute in time aspect are greatly concerned. For example, whether a distributed task is limited to complete specified action under the deadline, whether the overall task set meets end to end delay requirements, whether a variety of relationship in complex system environment would affect the task execution time, etc. Those are decidable to determine the task schedulability in system. Formal method provides a thought to solve the above problems. With the rigorous nature, formal approaches may apply at different software engineering activities to accurately present the state, the object and the result of action, and avoid the ambiguous specification of natural language, also provide the verification to confirm the correctness of the results achieved. Finite state machine is a typical formal method. Timed automata is a finite state machine increasing time constraints about system clock to express relationship between time and state. On this basis, in order to avoid the interference of the same permission level, the system needs a reasonable division between time and space to ensure the high credibility of embedded system.At first, this thesis abstracts task model of the distributed real-time target system, and introduces a scheduling checking tool using plug-in development and implementation in the theory of timed automata. Based on the basic framework of that tool, we refine on areas such as distributed multi-processor support, complex system environment, the clock expression and efficiency, and compare with the previous version. Subsequently, this thesis emphasizes the isolation and protection during the division of time and space of system and expand the partition concept. After that this thesis designs and implements a simulation module based on partition scheduling in conformity with the international standard ARTNC653 to enhance the target system's high reliability. At last, the thesis discusses mainstream system performance analysis methods in real-time currently, then summarizes Holistic scheduling, Real-Time Calculus and simulation method on characteristics and representative tools. Through the comparison with three performance testing benchmarks, the thesis evaluates various analytical tools till the advantage and pitfall conclusion.