Verifying Weakly-Hard Real-Time Properties of Traffic Streams in Switched Networks

In this paper, we introduce the first verification method which is able to provide weakly-hard real-time guarantees for tasks and task chains in systems with multiple resources under partitioned scheduling with fixed priorities. Existing weakly-hard real-time verification techniques are restricted today to systems with a single resource. A weakly-hard real-time guarantee specifies an upper bound on the maximum number m of deadline misses of a task in a sequence of k consecutive executions. Such a guarantee is useful if a task can experience a bounded number of deadline misses without impacting the system mission. We present our verification method in the context of switched networks with traffic streams between nodes, and demonstrate its practical applicability in an automotive case study

Exploiting Execution Dynamics in Timing Analysis Using Job Sequences

International audienceWorst case design as needed for critical systems usually resorts to established methods for worst case response time analysis which rely on the worst case execution time of tasks and the minimum temporal distance between task activations. The result is often very pessimistic when compared to the real worst case load. Many feasible designs are therefore rejected under such analyses. Using worst case models based on job sequences rather than single jobs leads to less pessimistic results and makes worst case design more practical. This paper outlines existing modeling and analysis techniques which are based on job sequences and refers to several examples from automotive design where great benefits were demonstrated

System Level LET with Application to Automotive Design

The logical execution time (LET) programming model has been applied in the automotive industry to master multicore programming of large task systems with complex dependencies. Recent developments in electric powertrains and autonomous vehicle functions raise parallel programming from the multicore level to the vehicle level where the requirements for LET application do not hold any more. This paper introduces System Level LET (SL LET), an extension of LET with relaxed synchronization requirements. While related extensions have been proposed for specific scheduling and communication models before, SL LET can be used with a variety of scheduling algorithms and communication semantics. Furthermore, it can be applied to systems with combinations of LET and other programming models. Yet, SL LET allows end-to-end timing guarantees and preserves essential LET properties required for automotive systems. For illustration, we apply the model to an electric vehicle use case

Finite Ready Queues As a Mean for Overload Reduction in Weakly-Hard Real-Time Systems

International audienceFinite ready queues, implemented by buuers, are a system reality in embedded real-time computing systems and networks. The dimen-sioning of queues is subject to constraints in industrial practice, and often the queue capacity is suucient for typical system behavior but is not suucient in peak overload conditions. This may lead to overrow and consequently to the discarding of jobs. In this paper, we explore whether nite queue capacity can also be used as a mean of design in order to reduce workload peaks and thus shorten a transient overload phase. We present an analysis method which is to the best of our knowledge the rst one able to give (a) worst-case response times guarantees as well as (b) weakly-hard guarantees for tasks which are executed on a computing system with nite queues. Experimental results show that nite queue capacity may only a have weak overload limiting eeect. This unexpected outcome can be explained by the system behavior in the worst-case corner cases. The analysis shows nevertheless that a trade-oo between weakly-hard guarantees and queue sizes is possible

System Level LET with Application to Automotive Design

The logical execution time (LET) programming model has been applied in the automotive industry to master multicore programming of large task systems with complex dependencies. Recent developments in electric powertrains and autonomous vehicle functions raise parallel programming from the multicore level to the vehicle level where the requirements for LET application do not hold any more. This paper introduces System Level LET (SL LET), an extension of LET with relaxed synchronization requirements. While related extensions have been proposed for specific scheduling and communication models before, SL LET can be used with a variety of scheduling algorithms and communication semantics. Furthermore, it can be applied to systems with combinations of LET and other programming models. Yet, SL LET allows end-to-end timing guarantees and preserves essential LET properties required for automotive systems. For illustration, we apply the model to an electric vehicle use case