Worst-case temporal analysis of real-time dynamic streaming applications
FM Firew Siyoum · TU/e Research Portal · 2014
Contemporary embedded wireless and multimedia applications are typically implemented on a Multiprocessor System-on-Chip (MPSoC) for power and performance reasons.The MPSoC commonly comprises heterogeneous resources that are shared between multiple applications under different scheduling policies.These applications have strict real-time constraints such as worst-case throughput and maximum end-to-end latency.It is crucial to guarantee that such constraints are satisfied at all operating conditions.Simulation and measurement-based analysis techniques cannot guarantee worst-case temporal bounds, since it is impractical to cover all possible system behaviors.Thus, analytical techniques are often used to compute conservative temporal bounds.In particular, dataflow models of computation (MoCs) have been widely used to model and analyse streaming applications.A challenge to dataflow-based design-time analysis of present-day streaming applications is their dynamic execution behavior.These applications change their graph structure, data rates and computation loads, depending on their operating modes.A conservative static dataflow model, such as Synchronous Dataflow (SDF), abstracts from such varying operating modes for the sake of analysability.However, the abstraction leads to overly pessimistic temporal bounds.This further leads to unnecessarily large resource allocations to guarantee real-time latency and throughput requirements.Thus, a refined temporal analysis that considers the different operating modes is crucial to compute tight real-time temporal bounds and, consequently, avoid unnecessary overallocation of scarce MPSoC resources.Moreover, the temporal analysis should be fast enough to efficiently explore the application mapping design-space through an iterative process.To that end, this thesis presents a number of contributions that form a framework to analytically determine real-time temporal bounds of streaming applications that are mapped onto a heterogeneous MPSoC platform.