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Documents authored by Merriam, Nicholas


Document
Hybrid measurement-based WCET analysis at the source level using object-level traces

Authors: Adam Betts, Nicholas Merriam, and Guillem Bernat

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


Abstract
Hybrid measurement-based approaches to worst-case execution time (WCET) analysis combine measured execution times of small program segments using static analysis of the larger software structure. In order to make the necessary measurements, instrumentation code is added to generate a timestamped trace from the running program. The intrusive presence of this instrumentation code incurs a timing penalty, widely referred to as the probe effect. However, recent years have seen the emergence of trace capability at the hardware level, effectively opening the door to probe-free analysis. Relying on hardware support forces the WCET analysis to the object-code level, since that is all that is known by the hardware. A major disadvantage of this is that it is expensive for a typical software engineer to interpret the results, since most engineers are familiar with the source code but not the object code. Meaningful WCET analysis involves not just running a tool to obtain an overall WCET value but also understanding which sections of code consume most of the WCET in order that corrective actions, such as optimisation, can be applied if the WCET value is too large. The main contribution of this paper is a mechanism by which hybrid WCET analysis can still be performed at the source level when the timestamped trace has been collected at the object level by state-of-the-art hardware. This allows existing, commercial tools, such as \rapitime{}, to operate without the need for intrusive instrumentation and thus without the probe effect.

Cite as

Adam Betts, Nicholas Merriam, and Guillem Bernat. Hybrid measurement-based WCET analysis at the source level using object-level traces. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 54-63, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2010)


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@InProceedings{betts_et_al:OASIcs.WCET.2010.54,
  author =	{Betts, Adam and Merriam, Nicholas and Bernat, Guillem},
  title =	{{Hybrid measurement-based WCET analysis at the source level using object-level traces}},
  booktitle =	{10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
  pages =	{54--63},
  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.2010.54},
  URN =		{urn:nbn:de:0030-drops-28255},
  doi =		{10.4230/OASIcs.WCET.2010.54},
  annote =	{Keywords: WCET analysis, hybrid analysis, trace}
}
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}
}
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