A real time budgeting method for module-level-pipelined bus based system using bus scenarios

In designing bus based systems with parallel and pipelined architecture, it is important to derive a real time budget (a specified execution time limit) for each task of a bus based system while satisfying given end-to-end real-time constraints of the entire system such as throughput and latency constraints. In this paper, we define a bus scenario representing a set of possible execution sequences of tasks and bus transfers executed in a bus based system. Then we propose a method for deriving real time budgets of all the tasks running in parallel and pipelined fashion from the pair of a system configuration (such as bus topology) and a bus scenario. In deriving such real time budgets, we consider computational complexity of each task, the amount of bus transfers and bus arbitration policies (e.g. fixed priority or time divided round robin based arbitration). We show that the proposed method is effective for designing several bus based systems such as MPEG decoders.