@article{DeubzerMottokMargulletal., author = {Deubzer, Michael and Mottok, J{\"u}rgen and Margull, Ulrich and Niemetz, Michael and Wirrer, Gerhard}, title = {Efficient Scheduling of Reliable Automotive Multi-core Systems with PD² by Weakening ERfair Task System Requirements}, series = {Automotive Safety and Security}, journal = {Automotive Safety and Security}, pages = {53 -- 67}, abstract = {Partly Proportionate fair (Partly-Pfair) scheduling, which allows task migration at runtime and assigns each task processing time with regard to its weight, makes it possible to build highly efficient embedded multi-core systems. Due to its non-work-conserving behavior, which might leave the CPU idle even when tasks are ready to execute, tasks finish only shortly before their deadlines are reached. Benefits are lower task jitter, but additional workload, e.g. through interrupts, can lead to deadline violations. In this paper we present a work-conserving extension of Partly-Pfair scheduling, called PERfair scheduling and the algorithm P-ERfair-PD2 which applies Pfair modifications used for Partly-Pfair on the concept of ERfairness and PD2 policies. With a simulation based schedulability examination we show for multiple time base (MTB) task sets that P-ERfair- PD2 has the same performance as Partly-Pfair-PD2. Additionally, we show that P-ERfair- PD2 has a much higher robustness against perturbations, and therefore it is well suited for embedded domains, especially for the Automotive domain.}, language = {en} } @article{DeubzerSchillerMottoketal., author = {Deubzer, Michael and Schiller, Frank and Mottok, J{\"u}rgen and Niemetz, Michael and Margull, Ulrich}, title = {Effizientes Multicore-Scheduling in Eingebetteten Systemen - Teil 1: Algorithmen f{\"u}r zuverl{\"a}ssige Echtzeitsysteme}, series = {atp - Automatisierungstechnische Praxis}, journal = {atp - Automatisierungstechnische Praxis}, number = {9}, pages = {60 -- 67}, abstract = {Eingebettete Systeme unterliegen neben den funktionalen Anforderungen besonders nicht funktionalen Qualit{\"a}tsanforderungen wie Effizienz, Zuverl{\"a}ssigkeit und Echtzeitf{\"a}higkeit. Mit steigendem Bedarf an Rechenkapazit{\"a}t k{\"o}nnen bisherige Konzepte zur Leistungssteigerung von Singlecore-Systemen jedoch nicht mehr eingesetzt werden - der Umstieg auf Multicore-Systeme wird erforderlich. Im ersten Teil dieser Arbeit werden eine m{\"o}gliche Prozessorarchitektur f{\"u}r zuk{\"u}nftige Automotive Multicore-Systeme und die Abstraktion der Software f{\"u}r diese Systeme vorgestellt. Nach einer Klassifkation von Multicore-Scheduling-Algorithmen pr{\"a}sentieren wir exemplarisch einen Algorithmus mit statischer Taskallokation und einen Algorithmus mit dynamischer Taskallokation. Bei beiden Algorithmen handelt es sich um eine {\"U}berf{\"u}hrung theoretisch behandelter Algorithmen auf Automotive Systeme.}, language = {de} } @inproceedings{SchorerKuntzMottok, author = {Schorer, Michael and Kuntz, Stefan and Mottok, J{\"u}rgen}, title = {Verification of Behavioral Compatibility in the Virtual Integration Methodology}, series = {8th IEEE Workshop on Intelligent Solutions in Embedded Systems,Heraklion, Greece, July 2010}, booktitle = {8th IEEE Workshop on Intelligent Solutions in Embedded Systems,Heraklion, Greece, July 2010}, doi = {10.1109/WISES.2010.5548424}, pages = {35 -- 42}, abstract = {The advantages of component-based systems include reuse of generic components as well as adaption through variants. However, they bare a high risk of containing incompatibilities between components, due to the lack of control over the integration-relevant aspects of their components. Current development processes are able to detect incompatibilities between components only at very late stages of system development. The Virtual Integration methodology is an approach to detect and to solve compatibility issues during early stages of system design. The methodology supports developers with a set of measures to reduce the risk of incompatibilities to a minimum at each abstraction layer of their system architecture. Realtime requirements of embedded systems make it necessary to support the methodology with a formal model, which can describe dynamic properties of these systems. In our approach, we use interface automata because they offer a lightweight formalism to describe the behavior of components and to verify their compatibility based on these descriptions. In a feasibility study we show, to which extend interface automata are adequate for the foresaid purpose in the automotive application field.}, language = {en} } @article{DeubzerSchillerMottoketal., author = {Deubzer, Michael and Schiller, Frank and Mottok, J{\"u}rgen and Niemetz, Michael and Margull, Ulrich}, title = {Effizientes Multicore-Scheduling in Eingebetteten Systemen - Teil 2: Ein simulationsbasierter Ansatz zum Vergleich von Scheduling-Algorithmen}, series = {atp - Automatisierungstechnische Praxis}, volume = {52}, journal = {atp - Automatisierungstechnische Praxis}, number = {10}, abstract = {Eingebettete Systeme unterliegen neben den funktionalen Anforderungen besonders nichtfunktionalen Qualit{\"a}tsanforderungen wie Effizienz, Zuverl{\"a}ssigkeit und Echtzeitf{\"a}higkeit. Mit steigendem Bedarf an Rechenkapazit{\"a}t k{\"o}nnen bisherige Konzepte zur Leistungssteigerung von Singlecore-Systemen jedoch nicht mehr eingesetzt werden - der Umstieg auf Multicore-Systeme wird erforderlich. Im zweiten Teil dieser Arbeit wird ein simulationsbasierter Ansatz zum Vergleich von Multicore-Scheduling-Algorithmen vorgestellt, mit dem Algorithmen f{\"u}r Multicore-Systeme mit voller Migration und dynamischer Task-Priorit{\"a}t untersucht werden. Wir erweitern diesen Ansatz um ein Verfahren zur Untersuchung einer Tasksetmenge mit stochastisch beschriebenen Eigenschaften und vergleichen ihn mit den im Teil 1 beschriebenen Algorithmen BinPacking-EDF und P-ERfair-PD² f{\"u}r eine Gruppe von Automotive Powertrain Systemen.}, language = {de} } @inproceedings{DeubzerMargullMottoketal., author = {Deubzer, Michael and Margull, Ulrich and Mottok, J{\"u}rgen and Niemetz, Michael and Wirrer, Gerhard}, title = {Partly Proportionate Fair Multiprocessor Scheduling of Heterogeneous Task Systems}, series = {5th Embedded Real Time Software and Systems Conference, May 2010}, booktitle = {5th Embedded Real Time Software and Systems Conference, May 2010}, abstract = {Proportionate fair (Pfair) scheduling, which allows task migration at runtime and assigns each task processing time with regard to its weight, is one of the most efficient group of SMP multiprocessor scheduling algorithms known up to now. Drawbacks are tight requirements to the task system, namely the restriction to periodic task systems with synchronized task activation, quantized task execution time, and implicit task deadline. Most likely, a typical embedded real-time system does not fulfill these requirements. In this paper we address violations of these requirements. For heterogeneous task systems, we define the multiple time base (MTB) task system, which is a less pessimistic model than sporadic task systems and is used for automotive systems. We apply the concept of Pfair scheduling to MTB task systems, called partly proportionate fair (Partly-Pfair) scheduling. The restrictions on MTB task systems required for Partly-Pfair ness are weaker than restrictions on periodic task systems required for Pfair ness. In a simulation based study we examined the performance of Partly-Pfair-PD and found it capable to schedule feasible MTB task sets causing a load of up to 100\% of the system capacity.}, language = {en} } @inproceedings{BaerwaldHauffMottok, author = {B{\"a}rwald, Andreas and Hauff, Harald and Mottok, J{\"u}rgen}, title = {Qualification and Certification of Development Tools for Safety-Critical Applications}, series = {Automotive Safety \& Security}, booktitle = {Automotive Safety \& Security}, pages = {135 -- 149}, abstract = {This paper presents an overview on qualification and certification of tools used in the phases of the safety lifecycle for safety-critical applications, either for development or for verification and validation. Software development tools are widely used in the development of safety-critical software systems. More verification and validation procedures will be automated by software tools to reduce time consuming manual testing. The impact of software tools on functional safety is discussed. Based on normative regulations like IEC 61508 and ISO DIS 26262 different approaches for tool qualification and certification are presented.}, language = {en} } @inproceedings{SteindlMottokMeier, author = {Steindl, Michael and Mottok, J{\"u}rgen and Meier, Hans}, title = {SES-based Framework for Fault-tolerant Systems}, series = {8th IEEE Workshop on Intelligent Solutions in Embedded Systems, Heraklion, Greece, July 2010}, booktitle = {8th IEEE Workshop on Intelligent Solutions in Embedded Systems, Heraklion, Greece, July 2010}, doi = {10.1109/WISES.2010.5548427}, pages = {12 -- 16}, abstract = {Embedded real-time systems are often used in harsh environments, for example engine control systems in automotive vehicles. In such ECUs (Engine Control Unit) faults can lead to serious accidents. In this paper we propose a safety embedded architecture based on coded processing. This framework only needs two channels to provide fault tolerance and allows the detection and identification of permanent and transient faults. Once a fault is detected by an observer unit the SES guard makes it visible and initiates a suitable failure reaction.}, language = {en} } @article{BaerwaldHauffMottok, author = {B{\"a}rwald, Andreas and Hauff, Harald and Mottok, J{\"u}rgen}, title = {Certification of safety relevant systems - Benefits of using pre-certified components}, series = {Automotive Safety and Security}, journal = {Automotive Safety and Security}, language = {en} } @inproceedings{StappertJonssonMottoketal., author = {Stappert, Friedhelm and Jonsson, Jan and Mottok, J{\"u}rgen and Johansson, Rolf}, title = {A Design Framework for End-to-End Timing Constrained Automotive}, series = {5th Embedded Real Time Software and Systems Conference (ERTS2 2010), May 2010, Toulouse, France}, booktitle = {5th Embedded Real Time Software and Systems Conference (ERTS2 2010), May 2010, Toulouse, France}, language = {en} } @inproceedings{KraemerMottokMeier, author = {Kr{\"a}mer, Stefan and Mottok, J{\"u}rgen and Meier, Hans}, title = {Osek-basierende Implementierung des LLREF-Scheduling-Algorithmus f{\"u}r eine Dual-Core-Architektur}, series = {2. Landshuter Symposium Mikrosystemtechnik, Tagungsband, 24. une 25. Februar 2010, Hochschule Landshut}, booktitle = {2. Landshuter Symposium Mikrosystemtechnik, Tagungsband, 24. une 25. Februar 2010, Hochschule Landshut}, pages = {343 -- 349}, language = {de} }