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Documents authored by Ungerer, Theo

Document
DOI: 10.4230/LIPIcs.ECRTS.2018.13
Virtual Timing Isolation for Mixed-Criticality Systems

Authors: Johannes Freitag, Sascha Uhrig, and Theo Ungerer

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

Abstract
Commercial of the shelf multicore processors suffer from timing interferences between cores which complicates applying them in hard real-time systems like avionic applications. This paper proposes a virtual timing isolation of one main application running on one core from all other cores. The proposed technique is based on hardware external to the multicore processor and completely transparent to the main application i.e., no modifications of the software including the operating system are necessary. The basic idea is to apply a single-core execution based Worst Case Execution Time analysis and to accept a predefined slowdown during multicore execution. If the slowdown exceeds the acceptable bounds, interferences will be reduced by controlling the behavior of low-critical cores to keep the main application's progress inside the given bounds. Apart from the main goal of isolating the timing of the critical application a subgoal is also to efficiently use the other cores. For that purpose, three different mechanisms for controlling the non-critical cores are compared regarding efficient usage of the complete processor. Measuring the progress of the main application is performed by tracking the application's Fingerprint. This technology quantifies online any slowdown of execution compared to a given baseline (single-core execution). Several countermeasures to compensate unacceptable slowdowns are proposed and evaluated in this paper, together with an accuracy evaluation of the Fingerprinting. Our evaluations using the TACLeBench benchmark suite show that we can meet a given acceptable timing bound of 4 percent slowdown with a resulting real slowdown of only 3.27 percent in case of a pulse width modulated control and of 4.44 percent in the case of a frequency scaling control.
Cite as

Johannes Freitag, Sascha Uhrig, and Theo Ungerer. Virtual Timing Isolation for Mixed-Criticality Systems. In 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 106, pp. 13:1-13:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{freitag_et_al:LIPIcs.ECRTS.2018.13,
  author =	{Freitag, Johannes and Uhrig, Sascha and Ungerer, Theo},
  title =	{{Virtual Timing Isolation for Mixed-Criticality Systems}},
  booktitle =	{30th Euromicro Conference on Real-Time Systems (ECRTS 2018)},
  pages =	{13:1--13:23},
  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.2018.13},
  URN =		{urn:nbn:de:0030-drops-89904},
  doi =		{10.4230/LIPIcs.ECRTS.2018.13},
  annote =	{Keywords: multicore, hard real-time systems, timing isolation, safety-critical systems, mixed-criticality design and assurance}
}
Document
DOI: 10.4230/LITES-v004-i002-a002
EMSBench: Benchmark and Testbed for Reactive Real-Time Systems

Authors: Florian Kluge, Christine Rochange, and Theo Ungerer

Published in: LITES, Volume 4, Issue 2 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 2

Abstract
Benchmark suites for real-time embedded systems (RTES) usually contain only pure computations that are often used in this domain. They allow to evaluate computing performance, but do not reproduce the complexity and behaviour that is typical for such systems. Actual RTES have to interact with the physical environment, which is often reflected by code that is executed concurrently. In this article, we present the software package EMSBench that mimics such complex behaviour, and highlight some of its use cases. The benchmark code ems of EMSBench is based on the open-source engine management system (EMS) FreeEMS. Additionally, EMSBench contains a trace generator (tg) that provides input signals for ems and enables to execute ems close to reality. We provide detailed descriptions of the ems's execution behaviour and of trace generation. EMSBench can be used as test or benchmark program to compare different hardware platforms, e.g. in terms of schedulability. Also, we use EMSBench as a benchmark for static worst-case execution time (WCET) analysis and compare these results to measurements performed on existing hardware. Our results based on the OTAWA WCET estimation tool show WCET overestimations by the static analysis from 11.9% to 41.1% depending on the complexity of the analysed functions.
Cite as

Florian Kluge, Christine Rochange, and Theo Ungerer. EMSBench: Benchmark and Testbed for Reactive Real-Time Systems. In LITES, Volume 4, Issue 2 (2017). Leibniz Transactions on Embedded Systems, Volume 4, Issue 2, pp. 02:1-02:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@Article{kluge_et_al:LITES-v004-i002-a002,
  author =	{Kluge, Florian and Rochange, Christine and Ungerer, Theo},
  title =	{{EMSBench: Benchmark and Testbed for Reactive Real-Time Systems}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{02:1--02:23},
  ISSN =	{2199-2002},
  year =	{2017},
  volume =	{4},
  number =	{2},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v004-i002-a002},
  URN =		{urn:nbn:de:0030-drops-192698},
  doi =		{10.4230/LITES-v004-i002-a002},
  annote =	{Keywords: Real-time benchmark, WCET Analysis, Engine Management System}
}
Document
DOI: 10.4230/OASIcs.WCET.2016.10
Employing MPI Collectives for Timing Analysis on Embedded Multi-Cores

Authors: Martin Frieb, Alexander Stegmeier, Jörg Mische, and Theo Ungerer

Published in: OASIcs, Volume 55, 16th International Workshop on Worst-Case Execution Time Analysis (WCET 2016)

Abstract
Static WCET analysis of parallel programs running on shared-memory multicores suffers from high pessimism. Instead, distributed memory platforms which communicate via messages may be one solution for manycore systems. Message Passing Interface (MPI) is a standard for communication on these platforms. We show how its concept of collective operations can be employed for timing analysis. The idea is that the worst-case execution time (WCET) of a parallel program may be estimated by adding the WCET estimates of sequential program parts to the WCET estimates of communication parts. Therefore, we first analyse the two MPI operations MPI_Allreduce and MPI_Sendrecv. Employing these results, we make a timing analysis of the conjugate gradient (CG) benchmark from the NAS parallel benchmark suite.
Cite as

Martin Frieb, Alexander Stegmeier, Jörg Mische, and Theo Ungerer. Employing MPI Collectives for Timing Analysis on Embedded Multi-Cores. In 16th International Workshop on Worst-Case Execution Time Analysis (WCET 2016). Open Access Series in Informatics (OASIcs), Volume 55, pp. 10:1-10:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{frieb_et_al:OASIcs.WCET.2016.10,
  author =	{Frieb, Martin and Stegmeier, Alexander and Mische, J\"{o}rg and Ungerer, Theo},
  title =	{{Employing MPI Collectives for Timing Analysis on Embedded Multi-Cores}},
  booktitle =	{16th International Workshop on Worst-Case Execution Time Analysis (WCET 2016)},
  pages =	{10:1--10:11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-025-5},
  ISSN =	{2190-6807},
  year =	{2016},
  volume =	{55},
  editor =	{Schoeberl, Martin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2016.10},
  URN =		{urn:nbn:de:0030-drops-69034},
  doi =		{10.4230/OASIcs.WCET.2016.10},
  annote =	{Keywords: Real Time, Network on Chip, WCET, Timing Analysis, MPI}
}
Document
Complete Volume
DOI: 10.4230/OASIcs.PPES.2011
OASIcs, Volume 18, PPES'11, Complete Volume

Authors: Philipp Lucas, Lothar Thiele, Benoit Triquet, Theo Ungerer, and Reinhard Wilhelm

Published in: OASIcs, Volume 18, Bringing Theory to Practice: Predictability and Performance in Embedded Systems (2011)

Abstract
OASIcs, Volume 18, PPES'11, Complete Volume
Cite as

Bringing Theory to Practice: Predictability and Performance in Embedded Systems. Open Access Series in Informatics (OASIcs), Volume 18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)

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@Proceedings{lucas_et_al:OASIcs.PPES.2011,
  title =	{{OASIcs, Volume 18, PPES'11, Complete Volume}},
  booktitle =	{Bringing Theory to Practice: Predictability and Performance in Embedded Systems},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-28-6},
  ISSN =	{2190-6807},
  year =	{2012},
  volume =	{18},
  editor =	{Lucas, Philipp and Wilhelm, Reinhard},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.PPES.2011},
  URN =		{urn:nbn:de:0030-drops-35804},
  doi =		{10.4230/OASIcs.PPES.2011},
  annote =	{Keywords: Special-purpose and application-based systems\rbrack: Real-time and embedded systems}
}
Document
DOI: 10.4230/OASIcs.WCET.2010.90
WCET Analysis of a Parallel 3D Multigrid Solver Executed on the MERASA Multi-Core

Authors: Christine Rochange, Armelle Bonenfant, Pascal Sainrat, Mike Gerdes, Julian Wolf, Theo Ungerer, Zlatko Petrov, and Frantisek Mikulu

Published in: OASIcs, Volume 15, 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)

Abstract
To meet performance requirements as well as constraints on cost and power consumption, future embedded systems will be designed with multi-core processors. However, the question of timing analysability is raised with these architectures. In the MERASA project, a WCET-aware multi-core processor has been designed with the appropriate system software. They both guarantee that the WCET of tasks running on different cores can be safely analyzed since their possible interactions can be bounded. Nevertheless, computing the WCET of a parallel application is still not straightforward and a high-level preliminary analysis of the communication and synchronization patterns must be performed. In this paper, we report on our experience in evaluating the WCET of a parallel 3D multigrid solver code and we propose lines for further research on this topic.
Cite as

Christine Rochange, Armelle Bonenfant, Pascal Sainrat, Mike Gerdes, Julian Wolf, Theo Ungerer, Zlatko Petrov, and Frantisek Mikulu. WCET Analysis of a Parallel 3D Multigrid Solver Executed on the MERASA Multi-Core. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 90-100, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{rochange_et_al:OASIcs.WCET.2010.90,
  author =	{Rochange, Christine and Bonenfant, Armelle and Sainrat, Pascal and Gerdes, Mike and Wolf, Julian and Ungerer, Theo and Petrov, Zlatko and Mikulu, Frantisek},
  title =	{{WCET Analysis of a Parallel 3D Multigrid Solver Executed on the MERASA Multi-Core}},
  booktitle =	{10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
  pages =	{90--100},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-21-7},
  ISSN =	{2190-6807},
  year =	{2010},
  volume =	{15},
  editor =	{Lisper, Bj\"{o}rn},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2010.90},
  URN =		{urn:nbn:de:0030-drops-28298},
  doi =		{10.4230/OASIcs.WCET.2010.90},
  annote =	{Keywords: WCET analysis, multicore, timing predictability}
}
Document
DOI: 10.4230/DagSemProc.09201.6
Testing Run-time Evolving Systems

Authors: Tudor Dumitras, Frank Eliassen, Kurt Geihs, Henry Muccini, Andrea Polini, and Theo Ungerer

Published in: Dagstuhl Seminar Proceedings, Volume 9201, Self-Healing and Self-Adaptive Systems (2009)

Abstract
This document summarizes the results of the Working Group 4 - ``Testing'' - at the Dagstuhl Seminar 09201 ``Self-Healing and Self-Adaptive Systems'' (organized by A. Andrzejak, K. Geihs, O. Shehory and J. Wilkes). The seminar was held from May 10th 2009 to May 15th 2009 in Schloss Dagstuhl~--~Leibniz Center for Informatics.
Cite as

Tudor Dumitras, Frank Eliassen, Kurt Geihs, Henry Muccini, Andrea Polini, and Theo Ungerer. Testing Run-time Evolving Systems. In Self-Healing and Self-Adaptive Systems. Dagstuhl Seminar Proceedings, Volume 9201, pp. 1-7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{dumitras_et_al:DagSemProc.09201.6,
  author =	{Dumitras, Tudor and Eliassen, Frank and Geihs, Kurt and Muccini, Henry and Polini, Andrea and Ungerer, Theo},
  title =	{{Testing Run-time Evolving Systems}},
  booktitle =	{Self-Healing and Self-Adaptive Systems},
  pages =	{1--7},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{9201},
  editor =	{Artur Andrzejak and Kurt Geihs and Onn Shehory and John Wilkes},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09201.6},
  URN =		{urn:nbn:de:0030-drops-21065},
  doi =		{10.4230/DagSemProc.09201.6},
  annote =	{Keywords: Software Testing, Dynamically Evolving Systems}
}
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