Abstract-In distributed real-time embedded systems (DRE), it is common to model an application as a set of task chains. Each chain is activated cyclically and must complete before an end-to-end deadline. Each task of the chain is bound to execute on a particular processing element. The complexity of designing and analyzing a DRE can be reduced by applying a component-based methodology: each pipeline can be seen as a component with its temporal characteristic summarized in its interface. Analysis can be carried out in two different steps: 1) derivation of the temporal interface of a component pipeline; 2) analysis of the whole system by integrating the temporal interfaces of the components. In this paper, we propose to describe the temporal interface of a task pipeline by a set of demand bound functions (dbf), one per each node on which the pipeline executes, and we describe an algorithm for computing the dbfs. First, we show that the scenario of strictly periodic activations is not the worst when the pipelines are sporadically activated. Then, we propose an exact algorithm for computing the dbfs. We show by experimental analysis that the computation time of the algorithm on pipelines with reasonable size is below one second on common PCs. Finally, we estimate the pessimism introduced by our analysis with respect to holistic analysis by an extensive set of simulations. Today's applications are often developed by different vendors, each one providing separate components. As the application is distributed over several processing elements, components are of distributed nature as well. For example, this is the typical scenario in the automotive context [1], [2] . In the analysis of such a system it is of key importance to ensure that (i) each vendor provides only a synthetic information on the developed component (called component interface), and (ii) the integration of the components is made only on the information contained in the interface. In real-time systems, a component is equipped also with a temporal interface that contains information related to the amount of computational resource required by the component over time. The analysis is then performed in two steps: in the first step, each component is analyzed in isolation, summarizing its temporal behavior with a (possibly small) set of temporal parameters. Such temporal parameters will
The paper work in REF framed an algorithm for the demand bound function (DBF) that is being as one of the core of our affirmed methodology.
The Demand Bound Function Interface of Distributed Sporadic Pipelines of Tasks Scheduled by EDF
2010 22nd Euromicro Conference on Real-Time Systems
2010 22nd Euromicro Conference on Real-Time Systems
Computer Science