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This paper proposes an approach to modelling and analysis of distributed real-time actor systems, which is based on the Uppaal statistical model checker (SMC). SMC was chosen because it automatizes simulations, offers a temporal logic language to formalize specifications and exploits statistical techniques to infer quantitative measures about a model. The approach is integrated in a system life-cycle...
This paper proposes an extension to dataflow models with timing specifications to facilitate the construction of deterministic, platform independent, precisely timed models of software in cyber-physical systems (CPS). Dataflow models are often used to describe the software/cyber part of a CPS, owing to their succinct and analyzable representation of computation and concurrency. To capture the interaction...
Providing guarantees on the system behavior is mandatory in order to let the robots enter our every-day life. Among these guarantees, proving the fulfillment of real-time constraints on the software is a key issue, as their violation could result into unexpected and unsafe behaviors. In this paper, we present a methodology to guarantee real-time constraints on component-based software architectures...
Embedded systems for critical applications are typically specified with requirements on predictable timing and safety. While ensuring predictable timing, the RTFM-lang (Real-Time For the Masses) model of computation (MoC) currently lacks memory access protection among real-time tasks. In this paper, we discuss how to safely verify task execution given a specification using the RTFM-MoC. Furthermore,...
SDRAM is a shared resource in modern multi-core platforms executing multiple real-time (RT) streaming applications. It is crucial to analyze the minimum guaranteed SDRAM bandwidth to ensure that the requirements of the RT streaming applications are always satisfied. However, deriving the worstcase bandwidth (WCBW) is challenging because of the diverse memory traffic with variable transaction sizes...
While common task models in real-time analysis assume a task as being activated by a single event and producing a single outgoing event after its full completion, the event dependency analysis extended the model to allow for multiple outgoing events to occur already during the run-time of a single job. It uses the structure of a timing-annotated control flow graph to calculate the maximal densities...
In this paper a novel schedulability analysis technique of real-time systems is presented. The developed approach is based on the consideration of the reachability graph of the (untimed) underlying Petri net of the studied model. The schedulability analysis is then conducted in two steps. Once a feasible firing sequence (called occurrence sequence) is highlighted, this sequence is then described under...
Construction of a Real-Time System (RTS) out of a number of pre-fabricated pieces of software, otherwise known as components, is a pervasive area of interest. Typically, only relocatable object code of the component is shipped to the customer, so that it can later be linked into the overall application. Source code is therefore withheld, and disassembling of the object code is normally disallowed...
Static timing analysis of a hard real-time application is necessary to ensure that task-level timing deadlines are always met. In many cases, it is preferable to include details about the operating environment to ensure precise timing analysis. However, adding an environment model increases the overall state space being analyzed, which can result in longer analysis time. In this paper, we present...
Modern computing systems have adopted multicore architectures and multiprocessor systems on chip (MPSoCs) for accommodating the increasing demand on computation power. However, performance boosting is constrained by shared resources, such as buses, main memory, DMA, etc.This paper analyzes the worst-case completion (response) time for real-time tasks when time division multiple access (TDMA) policies...
Safety-critical hard real time systems as the flight control computer in avionics or airbag control software in the automotive industry need to be validated for their correct behavior. Besides the functional correctness, timely task completion is essential, i.e. the worst-case execution time (WCET) of each task in the system has to be determined. Saarland University and AbsInt GmbH have successfully...
Component-based development approaches are becoming commonplace in business applications: they must therefore have some merit. In striking contrast to that, their penetration in the industrial practice of high-integrity real-time systems is virtually nil. This oddity needs explaining. In this paper we reflect on the presumed reasons of this situation and elaborate on possible systematic remedies....
The Real-Time Calculus (RTC) framework proposed in [Chakraborty et al., DATE 2003] and subsequently extended in [Wandeler et al., Real-Time Systems 29(2-3), 2005] and a number of other papers is geared towards the analysis of real-time systems that process various types of streaming data. The main strength of RTC is a count-based abstraction, where arrival patterns of event streams are specified as...
Component-based development (CBD) of software, with its successes in enterprise computing, has the promise of being a good development model due to its cost effectiveness and potential for achieving high quality of components by virtue of reuse. However, for systems with dependability concerns, such as real-time systems, a major challenge in using CBD consists of predicting dependability attributes,...
Round-Robin scheduling is the most popular time triggered scheduling policy, and has been widely used in communication networks for the last decades. It is an efficient scheduling technique for integration of unrelated system parts, but the worst-case timing depends on the system properties in a very complex way. The existing works on response time analysis of task scheduled under Round-Robin determine...
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