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Documents authored by Wildermann, Stefan

Document
Complete Volume
DOI: 10.4230/OASIcs.NG-RES.2024
OASIcs, Volume 117, NG-RES 2024, Complete Volume

Authors: Patrick Meumeu Yomsi and Stefan Wildermann

Published in: OASIcs, Volume 117, Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024)

Abstract
OASIcs, Volume 117, NG-RES 2024, Complete Volume
Cite as

Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024). Open Access Series in Informatics (OASIcs), Volume 117, pp. 1-62, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Proceedings{yomsi_et_al:OASIcs.NG-RES.2024,
  title =	{{OASIcs, Volume 117, NG-RES 2024, Complete Volume}},
  booktitle =	{Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024)},
  pages =	{1--62},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-313-3},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{117},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2024},
  URN =		{urn:nbn:de:0030-drops-197028},
  doi =		{10.4230/OASIcs.NG-RES.2024},
  annote =	{Keywords: OASIcs, Volume 117, NG-RES 2024, Complete Volume}
}
Document
Front Matter
DOI: 10.4230/OASIcs.NG-RES.2024.0
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Patrick Meumeu Yomsi and Stefan Wildermann

Published in: OASIcs, Volume 117, Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024)

Abstract
Front Matter, Table of Contents, Preface, Conference Organization
Cite as

Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024). Open Access Series in Informatics (OASIcs), Volume 117, pp. 0:i-0:x, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{yomsi_et_al:OASIcs.NG-RES.2024.0,
  author =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{Fifth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2024)},
  pages =	{0:i--0:x},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-313-3},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{117},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2024.0},
  URN =		{urn:nbn:de:0030-drops-197032},
  doi =		{10.4230/OASIcs.NG-RES.2024.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
DOI: 10.4230/OASIcs.NG-RES.2023.7
RAVEN: Reinforcement Learning for Generating Verifiable Run-Time Requirement Enforcers for MPSoCs

Authors: Khalil Esper, Jan Spieck, Pierre-Louis Sixdenier, Stefan Wildermann, and Jürgen Teich

Published in: OASIcs, Volume 108, Fourth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2023)

Abstract
In embedded systems, applications frequently have to meet non-functional requirements regarding, e.g., real-time or energy consumption constraints, when executing on a given MPSoC target platform. Feedback-based controllers have been proposed that react to transient environmental factors by adapting the DVFS settings or degree of parallelism following some predefined control strategy. However, it is, in general, not possible to give formal guarantees for the obtained controllers to satisfy a given set of non-functional requirements. Run-time requirement enforcement has emerged as a field of research for the enforcement of non-functional requirements at run-time, allowing to define and formally verify properties on respective control strategies specified by automata. However, techniques for the automatic generation of such controllers have not yet been established. In this paper, we propose a technique using reinforcement learning to automatically generate verifiable feedback-based enforcers. For that, we train a control policy based on a representative input sequence at design time. The learned control strategy is then transformed into a verifiable enforcement automaton which constitutes our run-time control model that can handle unseen input data. As a case study, we apply the approach to generate controllers that are able to increase the probability of satisfying a given set of requirement verification goals compared to multiple state-of-the-art approaches, as can be verified by model checkers.
Cite as

Khalil Esper, Jan Spieck, Pierre-Louis Sixdenier, Stefan Wildermann, and Jürgen Teich. RAVEN: Reinforcement Learning for Generating Verifiable Run-Time Requirement Enforcers for MPSoCs. In Fourth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2023). Open Access Series in Informatics (OASIcs), Volume 108, pp. 7:1-7:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{esper_et_al:OASIcs.NG-RES.2023.7,
  author =	{Esper, Khalil and Spieck, Jan and Sixdenier, Pierre-Louis and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{RAVEN: Reinforcement Learning for Generating Verifiable Run-Time Requirement Enforcers for MPSoCs}},
  booktitle =	{Fourth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2023)},
  pages =	{7:1--7:16},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-268-6},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{108},
  editor =	{Terraneo, Federico and Cattaneo, Daniele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2023.7},
  URN =		{urn:nbn:de:0030-drops-177380},
  doi =		{10.4230/OASIcs.NG-RES.2023.7},
  annote =	{Keywords: Verification, Runtime Requirement Enforcement, Reinforcement Learning}
}
Document
DOI: 10.4230/OASIcs.NG-RES.2022.2
Multi-Requirement Enforcement of Non-Functional Properties on MPSoCs Using Enforcement FSMs - A Case Study

Authors: Khalil Esper, Stefan Wildermann, and Jürgen Teich

Published in: OASIcs, Volume 98, Third Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2022)

Abstract
Embedded system applications usually have to meet real-time, energy or safety requirements on programs typically concurrently executed on a given MPSoC target platform. Enforcing such properties, e.g., by adapting the number of processors allocated to a program or by scaling the voltage/frequency mode of involved processors, is a difficult problem to solve, especially with a typically large varying environmental input (workload) per execution. In a previous work [Esper et al., 2021], we formalized the related enforcement problem using (a) finite state machines to model enforcement strategies, (b) discrete-time Markov chains to model the uncertain environment determining the system’s workload, and (c) the system response that defines the feedback for the reactive enforcer. In this paper, we apply that approach to specify and verify multi-requirement enforcement strategies and assess a case study for enforcing two independent requirements at the same time, i.e., latency and energy consumption. We evaluate and compare different enforcement strategies using probabilistic verification for the use case of an object detection application.
Cite as

Khalil Esper, Stefan Wildermann, and Jürgen Teich. Multi-Requirement Enforcement of Non-Functional Properties on MPSoCs Using Enforcement FSMs - A Case Study. In Third Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2022). Open Access Series in Informatics (OASIcs), Volume 98, pp. 2:1-2:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{esper_et_al:OASIcs.NG-RES.2022.2,
  author =	{Esper, Khalil and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{Multi-Requirement Enforcement of Non-Functional Properties on MPSoCs Using Enforcement FSMs - A Case Study}},
  booktitle =	{Third Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2022)},
  pages =	{2:1--2:13},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-221-1},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{98},
  editor =	{Bertogna, Marko and Terraneo, Federico and Reghenzani, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2022.2},
  URN =		{urn:nbn:de:0030-drops-161102},
  doi =		{10.4230/OASIcs.NG-RES.2022.2},
  annote =	{Keywords: Runtime Requirement Enforcement, Verification, Finite State Machine, Markov Chain, Energy Consumption, Probabilistic Model Cheking, PCTL, MPSoC}
}
Document
Invited Paper
DOI: 10.4230/OASIcs.NG-RES.2021.1
A Comparative Evaluation of Latency-Aware Energy Optimization Approaches in Many-Core Systems (Invited Paper)

Authors: Khalil Esper, Stefan Wildermann, and Jürgen Teich

Published in: OASIcs, Volume 87, Second Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2021)

Abstract
Many applications vary a lot in execution time depending on their workload. A prominent example is image processing applications, where the execution time is dependent on the content or the size of the processed input images. An interesting case is when these applications have quality-of-service requirements such as soft deadlines, that they should meet as good as possible. A further complicated case is when such applications have one or even multiple further objectives to optimize like, e.g., energy consumption. Approaches that dynamically adapt the processing resources to application needs under multiple optimization goals and constraints can be characterized into the application-specific and feedback-based techniques. Whereas application-specific approaches typically statically use an offline stage to determine the best configuration for each known workload, feedback-based approaches, using, e.g., control theory, adapt the system without the need of knowing the effect of workload on these goals. In this paper, we evaluate a state-of-the-art approach of each of the two categories and compare them for image processing applications in terms of energy consumption and number of deadline misses on a given many-core architecture. In addition, we propose a second feedback-based approach that is based on finite state machines (FSMs). The obtained results suggest that whereas the state-of-the-art application-specific approach is able to meet a specified latency deadline whenever possible while consuming the least amount of energy, it requires a perfect characterization of the workload on a given many-core system. If such knowledge is not available, the feedback-based approaches have their strengths in achieving comparable energy savings, but missing deadlines more often.
Cite as

Khalil Esper, Stefan Wildermann, and Jürgen Teich. A Comparative Evaluation of Latency-Aware Energy Optimization Approaches in Many-Core Systems (Invited Paper). In Second Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2021). Open Access Series in Informatics (OASIcs), Volume 87, pp. 1:1-1:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{esper_et_al:OASIcs.NG-RES.2021.1,
  author =	{Esper, Khalil and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{A Comparative Evaluation of Latency-Aware Energy Optimization Approaches in Many-Core Systems}},
  booktitle =	{Second Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2021)},
  pages =	{1:1--1:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-178-8},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{87},
  editor =	{Bertogna, Marko and Terraneo, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2021.1},
  URN =		{urn:nbn:de:0030-drops-134779},
  doi =		{10.4230/OASIcs.NG-RES.2021.1},
  annote =	{Keywords: energy optimization, control-theory, timing analysis, soft real-time, dynamic voltage and frequency scaling, finite state machines, multi-core, many-core}
}
Document
DOI: 10.4230/OASIcs.NG-RES.2020.5
Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems

Authors: Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich

Published in: OASIcs, Volume 77, Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020)

Abstract
Dynamic resource management strategies in embedded many-core systems rely on task migration to adapt the deployment (mapping) of applications dynamically, e.g., for thermal/power management or load balancing. In case of hard real-time applications, however, the current practice of on-line application adaptation is limited to reconfiguring the whole application between a set of statically computed mappings with statically verified timing guarantees. This heavily restricts the application’s adaptability. To enable hard real-time task migrations in many-core systems without relying on a static analysis, this paper presents (i) a predictable task migration mechanism supported with (ii) a lightweight migration timing analysis and (iii) a lightweight migration timing feasibility check which can be applied on-line to bound on the worst-case temporal overhead of a migration and examine the admissibility of this overhead w.r.t. the hard real-time requirements of the application. For a variety of applications and many-core platforms, we experimentally demonstrate the feasibility of hard real-time task migrations, the lightness of the proposed timing analysis and feasibility check for on-line use, and the advantage of the proposed task migration approach over mapping reconfiguration as the state-of-the-art real-time adaptation approach for many-core systems.
Cite as

Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich. Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems. In Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020). Open Access Series in Informatics (OASIcs), Volume 77, pp. 5:1-5:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{pourmohseni_et_al:OASIcs.NG-RES.2020.5,
  author =	{Pourmohseni, Behnaz and Smirnov, Fedor and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems}},
  booktitle =	{Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020)},
  pages =	{5:1--5:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-136-8},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{77},
  editor =	{Bertogna, Marko and Terraneo, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2020.5},
  URN =		{urn:nbn:de:0030-drops-117816},
  doi =		{10.4230/OASIcs.NG-RES.2020.5},
  annote =	{Keywords: Hard real-time, task migration, timing analysis, dynamic resource management, multi-core, many-core}
}
Document
DOI: 10.4230/LIPIcs.ECRTS.2019.12
Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems

Authors: Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich

Published in: LIPIcs, Volume 133, 31st Euromicro Conference on Real-Time Systems (ECRTS 2019)

Abstract
Composable many-core systems enable the independent development and analysis of applications which will be executed on a shared platform where the mix of concurrently executed applications may change dynamically at run time. For each individual application, an off-line DSE is performed to compute several mapping alternatives on the platform, offering Pareto-optimal trade-offs in terms of real-time guarantees, resource usage, etc. At run time, one mapping is then chosen to launch the application on demand. In this context, to enable an independent analysis of each individual application at design time, so-called inter-application isolation schemes are applied which specify temporal/spatial isolation policies between applications. State-of-the-art composable many-core systems are developed based on a fixed isolation scheme that is exclusively applied to every resource in every mapping of every application and use a timing analysis tailored to that isolation scheme to derive timing guarantees for each mapping. A fixed isolation scheme, however, heavily restricts the explored space of solutions and can, therefore, lead to suboptimality. Lifting this restriction necessitates a timing analysis that is applicable to mappings with an arbitrary mix of isolation schemes on different resources. To address this issue, in this paper, we (a) present an isolation-aware timing analysis that - unlike existing analyses - can handle multiple isolation schemes in combination within one mapping and delivers safe yet tight timing bounds by identifying and excluding interference scenarios that can never happen under the given combination of isolation schemes. Based on the timing analysis, we (b) present a DSE which explores the choices of isolation scheme per resource within each mapping and uses the proposed timing analysis for timing verification. Experimental results demonstrate that, for a variety of real-time applications and many-core platforms, the proposed approach achieves an improvement of up to 67% in the quality of delivered mappings compared to approaches based on a fixed isolation scheme.
Cite as

Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich. Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems. In 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 133, pp. 12:1-12:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{pourmohseni_et_al:LIPIcs.ECRTS.2019.12,
  author =	{Pourmohseni, Behnaz and Smirnov, Fedor and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems}},
  booktitle =	{31st Euromicro Conference on Real-Time Systems (ECRTS 2019)},
  pages =	{12:1--12:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-110-8},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{133},
  editor =	{Quinton, Sophie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2019.12},
  URN =		{urn:nbn:de:0030-drops-107491},
  doi =		{10.4230/LIPIcs.ECRTS.2019.12},
  annote =	{Keywords: Many-core systems, timing analysis, design space exploration (DSE), isolation scheme, predictability, composability}
}
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