7 Search Results for "Ulbrich, Peter"


Document
A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems

Authors: Tim Rheinfels, Maximilian Gaukler, and Peter Ulbrich

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)


Abstract
The increasing complexity of real-time systems, comprising control tasks interacting with physics and non-control tasks, comes with substantial challenges: meeting various non-functional requirements implies conflicting design goals and a pronounced gap between worst and average-case resource requirements up to the overall timeliness being unverifiable. Mixed-criticality systems (MCS) is a well-known mitigation concept that operates the system in different criticality levels with timing guarantees given only to the subset of critical tasks. However, in many real-world applications, the criticality of control tasks is tied to the system’s physical state and control deviation, with safety specifications becoming a crucial design objective. Monitoring the physical state and adapting scheduling is inaccessible to MCS but has been dedicated mainly to control engineering approaches such as self-triggered (model-predictive) control. These, however, are hard to integrate with scheduling or expensive at run-time. This paper explores the potential of linking both worlds and elevating the physical state to a criticality criterion. We, therefore, propose a dedicated state estimation that can be leveraged as a run-time monitor for criticality mode changes. For this purpose, we develop a highly efficient one-dimensional state abstraction to be computed within the operating system’s scheduling. Furthermore, we show how to limit abstraction pessimism by feeding back state measurements robustly. The paper focuses on the control fundamentals and outlines how to leverage this new tool in adaptive scheduling. Our experimental results substantiate the efficiency and applicability of our approach.

Cite as

Tim Rheinfels, Maximilian Gaukler, and Peter Ulbrich. A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 11:1-11:26, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{rheinfels_et_al:LIPIcs.ECRTS.2023.11,
  author =	{Rheinfels, Tim and Gaukler, Maximilian and Ulbrich, Peter},
  title =	{{A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{11:1--11:26},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.11},
  URN =		{urn:nbn:de:0030-drops-180405},
  doi =		{10.4230/LIPIcs.ECRTS.2023.11},
  annote =	{Keywords: Real-time Control, Mixed-Criticality, Switched Systems, State Monitoring}
}
Document
Artifact
A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems (Artifact)

Authors: Tim Rheinfels, Maximilian Gaukler, and Peter Ulbrich

Published in: DARTS, Volume 9, Issue 1, Special Issue of the 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)


Abstract
The increasing complexity of real-time control systems, comprising control tasks interacting with physics and non-control tasks, comes with substantial challenges: meeting various non-functional requirements implies conflicting design goals and a pronounced gap between worst and average-case resource requirements up to the overall timeliness being unverifiable. Mixed-criticality systems (MCS) are a well-known mitigation concept that operate the system in different criticality levels with timing guarantees given only to the subset of critical tasks. In many real-world applications, the criticality of control applications is tied to the system’s physical state and control deviation, with safety specifications becoming a crucial design objective. Monitoring the physical state and adapting scheduling is inaccessible to MCS but has been dedicated mainly to control engineering approaches such as self-triggered (model-predictive) control. These, however, are hard to schedule or expensive at run time. This paper explores the potential of linking both worlds and elevating the physical state to a criticality criterion. We, therefore, propose a dedicated state estimation that can be leveraged as a run-time monitor for criticality mode changes. For this purpose, we develop a highly efficient one-dimensional state abstraction to be computed within the operating system’s scheduling. Furthermore, we show how to limit abstraction pessimism by feeding back state measurements robustly. The paper focuses on the control fundamentals and outlines how to leverage this new tool in adaptive scheduling. Our experimental results substantiate the efficiency and applicability of our approach.

Cite as

Tim Rheinfels, Maximilian Gaukler, and Peter Ulbrich. A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems (Artifact). In Special Issue of the 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Dagstuhl Artifacts Series (DARTS), Volume 9, Issue 1, pp. 1:1-1:3, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@Article{rheinfels_et_al:DARTS.9.1.1,
  author =	{Rheinfels, Tim and Gaukler, Maximilian and Ulbrich, Peter},
  title =	{{A New Perspective on Criticality: Efficient State Abstraction and Run-Time Monitoring of Mixed-Criticality Real-Time Control Systems (Artifact)}},
  pages =	{1:1--1:3},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2023},
  volume =	{9},
  number =	{1},
  editor =	{Rheinfels, Tim and Gaukler, Maximilian and Ulbrich, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.9.1.1},
  URN =		{urn:nbn:de:0030-drops-180229},
  doi =		{10.4230/DARTS.9.1.1},
  annote =	{Keywords: Real-time Control, Mixed-Criticality, Switched Systems, State Monitoring}
}
Document
A Hybrid Programming Language for Formal Modeling and Verification of Hybrid Systems

Authors: Eduard Kamburjan, Stefan Mitsch, and Reiner Hähnle

Published in: LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems. Leibniz Transactions on Embedded Systems, Volume 8, Issue 2


Abstract
Designing and modeling complex cyber-physical systems (CPS) faces the double challenge of combined discrete-continuous dynamics and concurrent behavior. Existing formal modeling and verification languages for CPS expose the underlying proof search technology. They lack high-level structuring elements and are not efficiently executable. The ensuing modeling gap renders formal CPS models hard to understand and to validate. We propose a high-level programming-based approach to formal modeling and verification of hybrid systems as a hybrid extension of an Active Objects language. Well-structured hybrid active programs and requirements allow automatic, reachability-preserving translation into differential dynamic logic, a logic for hybrid (discrete-continuous) programs. Verification is achieved by discharging the resulting formulas with the theorem prover KeYmaera X. We demonstrate the usability of our approach with case studies.

Cite as

Eduard Kamburjan, Stefan Mitsch, and Reiner Hähnle. A Hybrid Programming Language for Formal Modeling and Verification of Hybrid Systems. In LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems. Leibniz Transactions on Embedded Systems, Volume 8, Issue 2, pp. 04:1-04:34, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@Article{kamburjan_et_al:LITES.8.2.4,
  author =	{Kamburjan, Eduard and Mitsch, Stefan and H\"{a}hnle, Reiner},
  title =	{{A Hybrid Programming Language for Formal Modeling and Verification of Hybrid Systems}},
  booktitle =	{LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems},
  pages =	{04:1--04:34},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2022},
  volume =	{8},
  number =	{2},
  editor =	{Kamburjan, Eduard and Mitsch, Stefan and H\"{a}hnle, Reiner},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES.8.2.4},
  doi =		{10.4230/LITES.8.2.4},
  annote =	{Keywords: Active Objects, Differential Dynamic Logic, Hybrid Systems}
}
Document
TASKers: A Whole-System Generator for Benchmarking Real-Time-System Analyses

Authors: Christian Eichler, Tobias Distler, Peter Ulbrich, Peter Wägemann, and Wolfgang Schröder-Preikschat

Published in: OASIcs, Volume 63, 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)


Abstract
Implementation-based benchmarking of timing and schedulability analyses requires system code that can be executed on real hardware and has defined properties, for example, known worst-case execution times (WCETs) of tasks. Traditional approaches for creating benchmarks with such characteristics often result in implementations that do not resemble real-world systems, either due to work only being simulated by means of busy waiting, or because tasks have no control-flow dependencies between each other. In this paper, we address this problem with TASKers, a generator that constructs realistic benchmark systems with predefined properties. To achieve this, TASKers composes patterns of real-world programs to generate tasks that produce known outputs and exhibit preconfigured WCETs when being executed with certain inputs. Using this knowledge during the generation process, TASKers is able to specifically introduce inter-task control-flow dependencies by mapping the output of one task to the input of another.

Cite as

Christian Eichler, Tobias Distler, Peter Ulbrich, Peter Wägemann, and Wolfgang Schröder-Preikschat. TASKers: A Whole-System Generator for Benchmarking Real-Time-System Analyses. In 18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018). Open Access Series in Informatics (OASIcs), Volume 63, pp. 6:1-6:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{eichler_et_al:OASIcs.WCET.2018.6,
  author =	{Eichler, Christian and Distler, Tobias and Ulbrich, Peter and W\"{a}gemann, Peter and Schr\"{o}der-Preikschat, Wolfgang},
  title =	{{TASKers: A Whole-System Generator for Benchmarking Real-Time-System Analyses}},
  booktitle =	{18th International Workshop on Worst-Case Execution Time Analysis (WCET 2018)},
  pages =	{6:1--6:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-073-6},
  ISSN =	{2190-6807},
  year =	{2018},
  volume =	{63},
  editor =	{Brandner, Florian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2018.6},
  URN =		{urn:nbn:de:0030-drops-97528},
  doi =		{10.4230/OASIcs.WCET.2018.6},
  annote =	{Keywords: benchmarking real-time-system analyses, task-set generation, whole-system generation, static timing analysis, WCET analysis}
}
Document
Whole-System Worst-Case Energy-Consumption Analysis for Energy-Constrained Real-Time Systems

Authors: Peter Wägemann, Christian Dietrich, Tobias Distler, Peter Ulbrich, and Wolfgang Schröder-Preikschat

Published in: LIPIcs, Volume 106, 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)


Abstract
Although internal devices (e.g., memory, timers) and external devices (e.g., transceivers, sensors) significantly contribute to the energy consumption of an embedded real-time system, their impact on the worst-case response energy consumption (WCRE) of tasks is usually not adequately taken into account. Most WCRE analysis techniques, for example, only focus on the processor and therefore do not consider the energy consumption of other hardware units. Apart from that, the typical approach for dealing with devices is to assume that all of them are always activated, which leads to high WCRE overestimations in the general case where a system switches off the devices that are currently not needed in order to minimize energy consumption. In this paper, we present SysWCEC, an approach that addresses these problems by enabling static WCRE analysis for entire real-time systems, including internal as well as external devices. For this purpose, SysWCEC introduces a novel abstraction, the power-state-transition graph, which contains information about the worst-case energy consumption of all possible execution paths. To construct the graph, SysWCEC decomposes the analyzed real-time system into blocks during which the set of active devices in the system does not change and is consequently able to precisely handle devices being dynamically activated or deactivated.

Cite as

Peter Wägemann, Christian Dietrich, Tobias Distler, Peter Ulbrich, and Wolfgang Schröder-Preikschat. Whole-System Worst-Case Energy-Consumption Analysis for Energy-Constrained Real-Time Systems. In 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 106, pp. 24:1-24:25, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@InProceedings{wagemann_et_al:LIPIcs.ECRTS.2018.24,
  author =	{W\"{a}gemann, Peter and Dietrich, Christian and Distler, Tobias and Ulbrich, Peter and Schr\"{o}der-Preikschat, Wolfgang},
  title =	{{Whole-System Worst-Case Energy-Consumption Analysis for Energy-Constrained Real-Time Systems}},
  booktitle =	{30th Euromicro Conference on Real-Time Systems (ECRTS 2018)},
  pages =	{24:1--24:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-075-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{106},
  editor =	{Altmeyer, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2018.24},
  URN =		{urn:nbn:de:0030-drops-89795},
  doi =		{10.4230/LIPIcs.ECRTS.2018.24},
  annote =	{Keywords: energy-constrained real-time systems, worst-case energy consumption (WCEC), worst-case response energy consumption (WCRE), static whole-system analysis}
}
Document
Whole-System WCEC Analysis for Energy-Constrained Real-Time Systems (Artifact)

Authors: Peter Wägemann, Christian Dietrich, Tobias Distler, Peter Ulbrich, and Wolfgang Schröder-Preikschat

Published in: DARTS, Volume 4, Issue 2, Special Issue of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)


Abstract
Although internal devices (e.g., memory, timers) and external devices (e.g., sensors, transceivers) significantly contribute to the energy consumption of an embedded real-time system, their impact on the worst-case response energy consumption (WCRE) of tasks is usually not adequately taken into account. Most WCRE analysis techniques only focus on the processor and neglect the energy consumption of other hardware units that are temporarily activated and deactivated in the system. To solve the problem of system-wide energy-consumption analysis, we present SysWCEC, an approach that addresses these problems by enabling static WCRE analysis for entire real-time systems, including internal as well as external devices. For this purpose, SysWCEC introduces a novel abstraction, the power-state--transition graph, which contains information about the worst-case energy consumption of all possible execution paths. To construct the graph, SysWCEC decomposes the analyzed real-time system into blocks during which the set of active devices in the system does not change and is consequently able to precisely handle devices being dynamically activated or deactivated. In this artifact evaluation, which accompanies our related conference paper, we present easy to reproduce WCRE analyses with the SysWCEC framework using several benchmarks. The artifact comprises the generation of the power-state--transition graph from a given benchmark system and the formulation of an integer linear program whose solution eventually yields safe WCRE bounds.

Cite as

Peter Wägemann, Christian Dietrich, Tobias Distler, Peter Ulbrich, and Wolfgang Schröder-Preikschat. Whole-System WCEC Analysis for Energy-Constrained Real-Time Systems (Artifact). In Special Issue of the 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Dagstuhl Artifacts Series (DARTS), Volume 4, Issue 2, pp. 7:1-7:4, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)


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@Article{wagemann_et_al:DARTS.4.2.7,
  author =	{W\"{a}gemann, Peter and Dietrich, Christian and Distler, Tobias and Ulbrich, Peter and Schr\"{o}der-Preikschat, Wolfgang},
  title =	{{Whole-System WCEC Analysis for Energy-Constrained Real-Time Systems (Artifact)}},
  pages =	{7:1--7:4},
  journal =	{Dagstuhl Artifacts Series},
  ISSN =	{2509-8195},
  year =	{2018},
  volume =	{4},
  number =	{2},
  editor =	{W\"{a}gemann, Peter and Dietrich, Christian and Distler, Tobias and Ulbrich, Peter and Schr\"{o}der-Preikschat, Wolfgang},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DARTS.4.2.7},
  URN =		{urn:nbn:de:0030-drops-89756},
  doi =		{10.4230/DARTS.4.2.7},
  annote =	{Keywords: energy-constrained real-time systems, worst-case energy consumption (WCEC), worst-case response energy consumption (WCRE), static whole-system analysi}
}
Document
Characterizing Data Dependence Constraints for Dynamic Reliability Using n-Queens Attack Domains

Authors: Eric W. D. Rozier, Kristin Y. Rozier, and Ulya Bayram

Published in: LITES, Volume 4, Issue 1 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 1


Abstract
As data centers attempt to cope with the exponential growth of data, new techniques for intelligent, software-defined data centers (SDDC) are being developed to confront the scale and pace of changing resources and requirements.  For cost-constrained environments, like those increasingly present in scientific research labs, SDDCs also may provide better reliability and performability with no additional hardware through the use of dynamic syndrome allocation. To do so, the middleware layers of SDDCs must be able to calculate and account for complex dependence relationships to determine an optimal data layout.  This challenge is exacerbated by the growth of constraints on the dependence problem when available resources are both large (due to a higher number of syndromes that can be stored) and small (due to the lack of available space for syndrome allocation). We present a quantitative method for characterizing these challenges using an analysis of attack domains for high-dimension variants of the $n$-queens problem that enables performable solutions via the SMT solver Z3. We demonstrate correctness of our technique, and provide experimental evidence of its efficacy; our implementation is publicly available.

Cite as

Eric W. D. Rozier, Kristin Y. Rozier, and Ulya Bayram. Characterizing Data Dependence Constraints for Dynamic Reliability Using n-Queens Attack Domains. In LITES, Volume 4, Issue 1 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 1, pp. 05:1-05:26, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2017)


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@Article{rozier_et_al:LITES-v004-i001-a005,
  author =	{Rozier, Eric W. D. and Rozier, Kristin Y. and Bayram, Ulya},
  title =	{{Characterizing Data Dependence Constraints for Dynamic Reliability Using n-Queens Attack Domains}},
  booktitle =	{LITES, Volume 4, Issue 1 (2017)},
  pages =	{05:1--05:26},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2017},
  volume =	{4},
  number =	{1},
  editor =	{Rozier, Eric W. D. and Rozier, Kristin Y. and Bayram, Ulya},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v004-i001-a005},
  doi =		{10.4230/LITES-v004-i001-a005},
  annote =	{Keywords: SMT, Data dependence, n-queens}
}
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