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Documents authored by Sainrat, Pascal


Document
Validation of Processor Timing Models Using Cycle-Accurate Timing Simulators

Authors: Alban Gruin, Thomas Carle, Christine Rochange, and Pascal Sainrat

Published in: OASIcs, Volume 114, 21th International Workshop on Worst-Case Execution Time Analysis (WCET 2023)


Abstract
We propose a workflow to help find errors in the processor models that are used to prove their timing predictability. Recently, several papers have modeled processor cores using formal models that represent how instructions progress through the pipeline in each execution cycle. However, such models grow with the complexity of the cores and they are built by hand, using a description of the core, usually the HDL-level code. Such a task is error-prone, and verifying that the model actually captures the core’s timing behavior is required, otherwise the proofs become useless. Our workflow simulates the execution of benchmark applications using the HDL specification of a core in order to extract timing information as well as other relevant information (e.g. cache miss events, branch mispredictions). This information is used to replay the execution in a simulator of the core timing model, and to determine whether or not the model accurately represents the execution timing of the instructions. To avoid writing the simulator by hand for each new core, or new variation of a core, we developed a compiler that translates the timing model of a core into a C++ program. We evaluated our approach on the open source MINOTAuR core and we show how it enabled us to detect and correct errors in its model.

Cite as

Alban Gruin, Thomas Carle, Christine Rochange, and Pascal Sainrat. Validation of Processor Timing Models Using Cycle-Accurate Timing Simulators. In 21th International Workshop on Worst-Case Execution Time Analysis (WCET 2023). Open Access Series in Informatics (OASIcs), Volume 114, pp. 2:1-2:12, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{gruin_et_al:OASIcs.WCET.2023.2,
  author =	{Gruin, Alban and Carle, Thomas and Rochange, Christine and Sainrat, Pascal},
  title =	{{Validation of Processor Timing Models Using Cycle-Accurate Timing Simulators}},
  booktitle =	{21th International Workshop on Worst-Case Execution Time Analysis (WCET 2023)},
  pages =	{2:1--2:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-293-8},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{114},
  editor =	{W\"{a}gemann, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2023.2},
  URN =		{urn:nbn:de:0030-drops-184319},
  doi =		{10.4230/OASIcs.WCET.2023.2},
  annote =	{Keywords: Processor model, timing predictability, simulator generation}
}
Document
Automatic WCET Analysis of Real-Time Parallel Applications

Authors: Haluk Ozaktas, Christine Rochange, and Pascal Sainrat

Published in: OASIcs, Volume 30, 13th International Workshop on Worst-Case Execution Time Analysis (2013)


Abstract
Tomorrow's real-time embedded systems will be built upon multicore architectures. This raises two challenges. First, shared resources should be arbitrated in such a way that the WCET of independent threads running concurrently can be computed: in this paper, we assume that timepredictable multicore architectures are available. The second challenge is to develop software that achieves a high level of performance without impairing timing predictability. We investigate parallel software based on the POSIX threads standard and we show how the WCET of a parallel program can be analysed. We report experimental results obtained for typical parallel programs with an extended version of the OTAWA toolset.

Cite as

Haluk Ozaktas, Christine Rochange, and Pascal Sainrat. Automatic WCET Analysis of Real-Time Parallel Applications. In 13th International Workshop on Worst-Case Execution Time Analysis. Open Access Series in Informatics (OASIcs), Volume 30, pp. 11-20, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)


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@InProceedings{ozaktas_et_al:OASIcs.WCET.2013.11,
  author =	{Ozaktas, Haluk and Rochange, Christine and Sainrat, Pascal},
  title =	{{Automatic WCET Analysis of Real-Time Parallel Applications}},
  booktitle =	{13th International Workshop on Worst-Case Execution Time Analysis},
  pages =	{11--20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-54-5},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{30},
  editor =	{Maiza, Claire},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2013.11},
  URN =		{urn:nbn:de:0030-drops-41186},
  doi =		{10.4230/OASIcs.WCET.2013.11},
  annote =	{Keywords: WCET analysis, parallel programming, thread synchronisation}
}
Document
Multi-architecture Value Analysis for Machine Code

Authors: Hugues Cassé, Florian Birée, and Pascal Sainrat

Published in: OASIcs, Volume 30, 13th International Workshop on Worst-Case Execution Time Analysis (2013)


Abstract
Safety verification of critical real-time embedded systems requires Worst Case Execution Time information (WCET). Among the existing approaches to estimate the WCET, static analysis at the machine code level has proven to get safe results. A lot of different architectures are used in real-time systems but no generic solution provides the ability to perform static analysis of values handled by machine instructions. Nonetheless, results of such analyses are worth to improve the precision of other analyzes like data cache, indirect branches, etc. This paper proposes a semantic language aimed at expressing semantics of machine instructions whatever the underlying instruction set is. This ensures abstraction and portability of the value analysis or any analysis based on the semantic expression of the instructions. As a proof of concept, we adapted and refined an existing analysis representing values as Circular-Linear Progression (CLP), that is, as a sparse integer interval effective to model pointers. In addition, we show how our semantic instructions allow to build back conditions of loop in order to refine the CLP values and improve the precision of the analysis.Both contributions have been implemented in our framework, OTAWA, and experimented on the Malärdalen benchmark to desmonstrate the effectiveness of the approach.

Cite as

Hugues Cassé, Florian Birée, and Pascal Sainrat. Multi-architecture Value Analysis for Machine Code. In 13th International Workshop on Worst-Case Execution Time Analysis. Open Access Series in Informatics (OASIcs), Volume 30, pp. 42-52, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)


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@InProceedings{casse_et_al:OASIcs.WCET.2013.42,
  author =	{Cass\'{e}, Hugues and Bir\'{e}e, Florian and Sainrat, Pascal},
  title =	{{Multi-architecture Value Analysis for Machine Code}},
  booktitle =	{13th International Workshop on Worst-Case Execution Time Analysis},
  pages =	{42--52},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-54-5},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{30},
  editor =	{Maiza, Claire},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2013.42},
  URN =		{urn:nbn:de:0030-drops-41211},
  doi =		{10.4230/OASIcs.WCET.2013.42},
  annote =	{Keywords: machine code, static analysis, value analysis, semantics}
}
Document
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
WCET 2008 -- Report from the Tool Challenge 2008 -- 8th Intl. Workshop on Worst-Case Execution Time (WCET) Analysis

Authors: Niklas Holsti, Jan Gustafsson, Guillem Bernat, Clément Ballabriga, Armelle Bonenfant, Roman Bourgade, Hugues Cassé, Daniel Cordes, Albrecht Kadlec, Raimund Kirner, Jens Knoop, Paul Lokuciejewski, Nicholas Merriam, Marianne de Michiel, Adrian Prantl, Bernhard Rieder, Christine Rochange, Pascal Sainrat, and Markus Schordan

Published in: OASIcs, Volume 8, 8th International Workshop on Worst-Case Execution Time Analysis (WCET'08) (2008)


Abstract
Following the successful WCET Tool Challenge in 2006, the second event in this series was organized in 2008, again with support from the ARTIST2 Network of Excellence. The WCET Tool Challenge 2008 (WCC'08) provides benchmark programs and poses a number of "analysis problems" about the dynamic, run-time properties of these programs. The participants are challenged to solve these problems with their program analysis tools. Two kinds of problems are defined: WCET problems, which ask for bounds on the execution time of chosen parts (subprograms) of the benchmarks, under given constraints on input data; and flow-analysis problems, which ask for bounds on the number of times certain parts of the benchmark can be executed, again under some constraints. We describe the organization of WCC'08, the benchmark programs, the participating tools, and the general results, successes, and failures. Most participants found WCC'08 to be a useful test of their tools. Unlike the 2006 Challenge, the WCC'08 participants include several tools for the same target (ARM7, LPC2138), and tools that combine measurements and static analysis, as well as pure static-analysis tools.

Cite as

Niklas Holsti, Jan Gustafsson, Guillem Bernat, Clément Ballabriga, Armelle Bonenfant, Roman Bourgade, Hugues Cassé, Daniel Cordes, Albrecht Kadlec, Raimund Kirner, Jens Knoop, Paul Lokuciejewski, Nicholas Merriam, Marianne de Michiel, Adrian Prantl, Bernhard Rieder, Christine Rochange, Pascal Sainrat, and Markus Schordan. WCET 2008 -- Report from the Tool Challenge 2008 -- 8th Intl. Workshop on Worst-Case Execution Time (WCET) Analysis. In 8th International Workshop on Worst-Case Execution Time Analysis (WCET'08). Open Access Series in Informatics (OASIcs), Volume 8, pp. 1-23, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2008)


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@InProceedings{holsti_et_al:OASIcs.WCET.2008.1663,
  author =	{Holsti, Niklas and Gustafsson, Jan and Bernat, Guillem and Ballabriga, Cl\'{e}ment and Bonenfant, Armelle and Bourgade, Roman and Cass\'{e}, Hugues and Cordes, Daniel and Kadlec, Albrecht and Kirner, Raimund and Knoop, Jens and Lokuciejewski, Paul and Merriam, Nicholas and de Michiel, Marianne and Prantl, Adrian and Rieder, Bernhard and Rochange, Christine and Sainrat, Pascal and Schordan, Markus},
  title =	{{WCET 2008 -- Report from the Tool Challenge 2008 -- 8th Intl. Workshop on Worst-Case Execution Time (WCET) Analysis}},
  booktitle =	{8th International Workshop on Worst-Case Execution Time Analysis (WCET'08)},
  pages =	{1--23},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-10-1},
  ISSN =	{2190-6807},
  year =	{2008},
  volume =	{8},
  editor =	{Kirner, Raimund},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2008.1663},
  URN =		{urn:nbn:de:0030-drops-16637},
  doi =		{10.4230/OASIcs.WCET.2008.1663},
  annote =	{Keywords: WCET analysis, benchmark}
}
Document
Combining Symbolic Execution and Path Enumeration in Worst-Case Execution Time Analysis

Authors: Djemai Kebbal and Pascal Sainrat

Published in: OASIcs, Volume 4, 6th International Workshop on Worst-Case Execution Time Analysis (WCET'06) (2006)


Abstract
his paper examines the problem of determining bounds on execution time of real-time programs. Execution time estimation is generally useful in real-time software verification phase, but may be used in other phases of the design and execution of real-time programs (scheduling, automatic parallelizing, etc.). This paper is devoted to the worst-case execution time (WCET) analysis. We present a static WCET analysis approach aimed to automatically extract flow information used in WCET estimate computing. The approach combines symbolic execution and path enumeration. The main idea is to avoid unfolding loops performed by symbolic execution-based approaches while providing tight and safe WCET estimate.

Cite as

Djemai Kebbal and Pascal Sainrat. Combining Symbolic Execution and Path Enumeration in Worst-Case Execution Time Analysis. In 6th International Workshop on Worst-Case Execution Time Analysis (WCET'06). Open Access Series in Informatics (OASIcs), Volume 4, pp. 1-6, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2006)


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@InProceedings{kebbal_et_al:OASIcs.WCET.2006.675,
  author =	{Kebbal, Djemai and Sainrat, Pascal},
  title =	{{Combining Symbolic Execution and Path Enumeration in Worst-Case Execution Time Analysis}},
  booktitle =	{6th International Workshop on Worst-Case Execution Time Analysis (WCET'06)},
  pages =	{1--6},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-03-3},
  ISSN =	{2190-6807},
  year =	{2006},
  volume =	{4},
  editor =	{Mueller, Frank},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2006.675},
  URN =		{urn:nbn:de:0030-drops-6753},
  doi =		{10.4230/OASIcs.WCET.2006.675},
  annote =	{Keywords: Static WCET analysis, flow analysis, symbolic execution, path enumeration, loop analysis}
}
Document
PapaBench: a Free Real-Time Benchmark

Authors: Fadia Nemer, Hugues Cassé, Pascal Sainrat, Jean-Paul Bahsoun, and Marianne De Michiel

Published in: OASIcs, Volume 4, 6th International Workshop on Worst-Case Execution Time Analysis (WCET'06) (2006)


Abstract
This paper presents PapaBench, a free real-time benchmark and compares it with the existing benchmark suites. It is designed to be valuable for experimental works in WCET computation and may be also useful for scheduling analysis. This bench is based on the Paparazzi project that represents a real-time application, developed to be embedded on different Unmanned Aerial Vehicles (UAV). In this paper, we explain the transformation process of Paparazzi applied to obtain the PapaBench. We provide a high level AADL model, which reflects the behaviors of each component of the system and their interactions. As the source project, Paparazzi, PapaBench is delivered under the GNU license and is freely available to all researchers. Unlike other usual benchmarks widely used for WCET computation, this one is based on a real and complete real-time embedded application.

Cite as

Fadia Nemer, Hugues Cassé, Pascal Sainrat, Jean-Paul Bahsoun, and Marianne De Michiel. PapaBench: a Free Real-Time Benchmark. In 6th International Workshop on Worst-Case Execution Time Analysis (WCET'06). Open Access Series in Informatics (OASIcs), Volume 4, pp. 1-6, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2006)


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@InProceedings{nemer_et_al:OASIcs.WCET.2006.678,
  author =	{Nemer, Fadia and Cass\'{e}, Hugues and Sainrat, Pascal and Bahsoun, Jean-Paul and De Michiel, Marianne},
  title =	{{PapaBench: a Free Real-Time Benchmark}},
  booktitle =	{6th International Workshop on Worst-Case Execution Time Analysis (WCET'06)},
  pages =	{1--6},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-03-3},
  ISSN =	{2190-6807},
  year =	{2006},
  volume =	{4},
  editor =	{Mueller, Frank},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2006.678},
  URN =		{urn:nbn:de:0030-drops-6783},
  doi =		{10.4230/OASIcs.WCET.2006.678},
  annote =	{Keywords: Real-Time Benchmark, Complete Application, Worst Case Execution Time (WCET) Computation, Modeling}
}
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