Reliability Analysis of Task Model in Real-Time Fault-Tolerant Systems

One notable advantage of Model-Driven Architecture(MDA) method is that software developers could do sufficient analysis and tests on software models in the design phase, which helps construct high confidence on the expected software performance and behaviors. In this paper, we present a general reliability model, based on the relationship between real-time requirements and time costs of fault tolerance, to analyze reliability of the task execution model in real-time software design phase when using MDA method. This reliability model defines arrival rates of faults and fault-tolerant mechanisms to model non-permanent faults and the corresponding fault handling costs. By analyzing the probability of tasks being schedulable in the worst-case execution scenario, reliability and schedulability are combined into an unified analysis framework, and an algorithm for reliability analysis is also given under static priority scheduling. When no assumptions of fault occurrences made on the task model, this reliability model regresses to a generic schedulability model.