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DOI: 10.4230/OASIcs.WCET.2014.93

Identifying Relevant Parameters to Improve WCET Analysis

Authors: Jakob Zwirchmayr, Pascal Sotin, Armelle Bonenfant, Denis Claraz, and Philippe Cuenot

Published in: OASIcs, Volume 39, 14th International Workshop on Worst-Case Execution Time Analysis (2014)

Abstract

Highly-configurable systems usually depend on a large number of parameters imposed by both hardware and software configuration. Due to the pessimistic assumptions of WCET analysis, if left unspecified, they deteriorate the quality of WCET analysis. In such a case, supplying the WCET analyzer with additional information about parameters (a scenario), e.g. possible variable ranges or values, allows reducing WCET over-estimation, either by improving the estimate, or by validating the initial estimate for a specific configuration or mode of execution. Nevertheless, exhaustively specifying constraints on all parameters is usually infeasible and identifying relevant ones (i.e. those impacting the WCET) is difficult. To address this issue, we propose the branching statement analysis, which uses a source-based heuristic to compute branch weights and that aims at listing unbalanced conditionals that correspond to system parameters. The goal is to help system-experts identify and formulate concise scenarios about modes or configurations that have a positive impact on the quality of the WCET analysis.

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Jakob Zwirchmayr, Pascal Sotin, Armelle Bonenfant, Denis Claraz, and Philippe Cuenot. Identifying Relevant Parameters to Improve WCET Analysis. In 14th International Workshop on Worst-Case Execution Time Analysis. Open Access Series in Informatics (OASIcs), Volume 39, pp. 93-102, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2014)

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@InProceedings{zwirchmayr_et_al:OASIcs.WCET.2014.93,
  author =	{Zwirchmayr, Jakob and Sotin, Pascal and Bonenfant, Armelle and Claraz, Denis and Cuenot, Philippe},
  title =	{{Identifying Relevant Parameters to Improve WCET Analysis}},
  booktitle =	{14th International Workshop on Worst-Case Execution Time Analysis},
  pages =	{93--102},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-69-9},
  ISSN =	{2190-6807},
  year =	{2014},
  volume =	{39},
  editor =	{Falk, Heiko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2014.93},
  URN =		{urn:nbn:de:0030-drops-46085},
  doi =		{10.4230/OASIcs.WCET.2014.93},
  annote =	{Keywords: WCET Accuracy, Modes and Configuration, Flow Facts, Scenario Specification}
}

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DOI: 10.4230/OASIcs.WCET.2013.53

The Auspicious Couple: Symbolic Execution and WCET Analysis

Authors: Armin Biere, Jens Knoop, Laura Kovács, and Jakob Zwirchmayr

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

Abstract

We have recently shown that symbolic execution together with the implicit path enumeration technique can successfully be applied in the Worst-Case Execution Time (WCET) analysis of programs. Symbolic execution offers a precise framework for program analysis and tracks complex program properties by analyzing single program paths in isolation. This path-wise program exploration of symbolic execution is, however, computationally expensive, which often prevents full symbolic analysis of larger applications: the number of paths in a program increases exponentially with the number of conditionals, a situation denoted as the path explosion problem. Therefore, for applying symbolic execution in the timing analysis of programs, we propose to use WCET analysis as a guidance for symbolic execution in order to avoid full symbolic coverage of the program. By focusing only on paths or program fragments that are relevant for WCET analysis, we keep the computational costs of symbolic execution low. Our WCET analysis also profits from the precise results derived via symbolic execution. In this article we describe how use-cases of symbolic execution are materialized in the r-TuBound toolchain and present new applications of WCET-guided symbolic execution for WCET analysis. The new applications of selective symbolic execution are based on reducing the effort of symbolic analysis by focusing only on relevant program fragments. By using partial symbolic program coverage obtained by selective symbolic execution, we improve the WCET analysis and keep the effort for symbolic execution low.

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Armin Biere, Jens Knoop, Laura Kovács, and Jakob Zwirchmayr. The Auspicious Couple: Symbolic Execution and WCET Analysis. In 13th International Workshop on Worst-Case Execution Time Analysis. Open Access Series in Informatics (OASIcs), Volume 30, pp. 53-63, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2013)

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@InProceedings{biere_et_al:OASIcs.WCET.2013.53,
  author =	{Biere, Armin and Knoop, Jens and Kov\'{a}cs, Laura and Zwirchmayr, Jakob},
  title =	{{The Auspicious Couple: Symbolic Execution and WCET Analysis}},
  booktitle =	{13th International Workshop on Worst-Case Execution Time Analysis},
  pages =	{53--63},
  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-dev.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2013.53},
  URN =		{urn:nbn:de:0030-drops-41225},
  doi =		{10.4230/OASIcs.WCET.2013.53},
  annote =	{Keywords: WCET analysis, Symbolic execution, WCET refinement, Flow Facts}
}

Document

DOI: 10.4230/LIPIcs.ICLP.2010.303

Cutting-Edge Timing Analysis Techniques

Authors: Jakob Zwirchmayr

Published in: LIPIcs, Volume 7, Technical Communications of the 26th International Conference on Logic Programming (2010)

Abstract

This text gives an overview about my current research in timing analysis at the Vienna University of Technology. After a short introduction to the topic follows the description of an approach relying on CLP, the implicit path enumeration technique (IPET). This technique is also used in a tool developed at the institute of Computer Languages (TuBound). Current timing analysis tools suffer from a few flaws worth further investigation in order to achieve better results than current state-of-the-art timing analysis tools.

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Jakob Zwirchmayr. Cutting-Edge Timing Analysis Techniques. In Technical Communications of the 26th International Conference on Logic Programming. Leibniz International Proceedings in Informatics (LIPIcs), Volume 7, pp. 303-305, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{zwirchmayr:LIPIcs.ICLP.2010.303,
  author =	{Zwirchmayr, Jakob},
  title =	{{Cutting-Edge Timing Analysis Techniques}},
  booktitle =	{Technical Communications of the 26th International Conference on Logic Programming},
  pages =	{303--305},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-17-0},
  ISSN =	{1868-8969},
  year =	{2010},
  volume =	{7},
  editor =	{Hermenegildo, Manuel and Schaub, Torsten},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ICLP.2010.303},
  URN =		{urn:nbn:de:0030-drops-26140},
  doi =		{10.4230/LIPIcs.ICLP.2010.303},
  annote =	{Keywords: Verification, timing analysis, hard real-time systems, static analysis, worst-case execution time, loop-invariants, nested loop, symbolic computation,}
}

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Identifying Relevant Parameters to Improve WCET Analysis

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The Auspicious Couple: Symbolic Execution and WCET Analysis

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Cutting-Edge Timing Analysis Techniques

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