Applying RMA to improve a high-speed, real time data acquisition system

Unlike other real-time systems, data acquisition applications spend most of their time performing synchronous and asynchronous I/O operations. This fact, that affects the tasks´ abilities to meet deadlines, can be modelled with some extensions to the classic rate monotonic schedulability test. In this paper, we address this issue by investigating a case study for the application of rate monotonic analysis (RMA) to data acquisition systems. We describe a technique for modelling tasks that perform asynchronous I/O at the end of their executing period; and we also show the logistic and technical problems that can arise when applying RMA at different stages during the development process of an application. We illustrate our ideas with a real-time data acquisition system that we have developed, characterized by a very heterogeneous architecture whose technological components have been pushed to the limits of their performance and capacity