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Documents authored by Lokuciejewski, Paul


Document
WCET-aware Software Based Cache Partitioning for Multi-Task Real-Time Systems

Authors: Sascha Plazar, Paul Lokuciejewski, and Peter Marwedel

Published in: OASIcs, Volume 10, 9th International Workshop on Worst-Case Execution Time Analysis (WCET'09) (2009)


Abstract
Caches are a source of unpredictability since it is very difficult to predict if a memory access results in a cache hit or miss. In systems running multiple tasks steered by a preempting scheduler, it is even impossible to determine the cache behavior since interrupt-driven schedulers lead to unknown points of time for context switches. Partitioned caches are already used in multi-task environments to increase the cache hit ratio by avoiding mutual eviction of tasks from the cache. For real-time systems, the upper bound of the execution time is one of the most important metrics, called the Worst-Case Execution Time (WCET). In this paper, we use partitioning of instruction caches as a technique to achieve tighter WCET estimations since tasks can not be evicted from their partition by other tasks. We propose a novel WCET-aware cache partitioning algorithm, which determines the optimal partition size for each task with focus on decreasing the system's WCET for a given set of possible partition sizes. Employing this algorithm, we are able to decrease the WCET depending on the number of tasks in a set by up to 34%. On average, reductions between 12% and 19% can be achieved.

Cite as

Sascha Plazar, Paul Lokuciejewski, and Peter Marwedel. WCET-aware Software Based Cache Partitioning for Multi-Task Real-Time Systems. In 9th International Workshop on Worst-Case Execution Time Analysis (WCET'09). Open Access Series in Informatics (OASIcs), Volume 10, pp. 1-11, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2009)


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@InProceedings{plazar_et_al:OASIcs.WCET.2009.2286,
  author =	{Plazar, Sascha and Lokuciejewski, Paul and Marwedel, Peter},
  title =	{{WCET-aware Software Based Cache Partitioning for Multi-Task Real-Time Systems}},
  booktitle =	{9th International Workshop on Worst-Case Execution Time Analysis (WCET'09)},
  pages =	{1--11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-14-9},
  ISSN =	{2190-6807},
  year =	{2009},
  volume =	{10},
  editor =	{Holsti, Niklas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.WCET.2009.2286},
  URN =		{urn:nbn:de:0030-drops-22860},
  doi =		{10.4230/OASIcs.WCET.2009.2286},
  annote =	{Keywords: WCET analysis, cache partitioning}
}
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
Design of a WCET-Aware C Compiler

Authors: Heiko Falk, Paul Lokuciejewski, and Henrik Theiling

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


Abstract
This paper presents techniques to tightly integrate worst-case execution time information into a compiler framework. Currently, a tight integration of WCET information into the compilation process is strongly desired, but only some ad-hoc approaches have been reported currently. Previous publications mainly used self-written WCET estimators with very limited functionality and preciseness during compilation. A very tight integration of a high quality industry-relevant WCET analyzer into a compiler was not yet achieved up to now. This work is the first to present techniques capable of achieving such a tight coupling between a compiler and the WCET analyzer aiT. This is done by automatically translating the assembly-like contents of the compiler's low-level intermediate representation (LLIR) to aiT's exchange format CRL2. Additionally, the results produced by the WCET analyzer are automatically collected and re-imported into the compiler infrastructure. The work described in this paper is smoothly integrated into a C compiler environment for the Infineon TriCore processor. It opens up new possibilities for the design of WCET-aware optimizations in the future. The concepts for extending the compiler infrastructure are kept very general so that they are not limited to WCET information. Rather, it is possible to use our structures also for multi-objective optimization of e.g. best-case execution time (BCET) or energy dissipation.

Cite as

Heiko Falk, Paul Lokuciejewski, and Henrik Theiling. Design of a WCET-Aware C Compiler. 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{falk_et_al:OASIcs.WCET.2006.673,
  author =	{Falk, Heiko and Lokuciejewski, Paul and Theiling, Henrik},
  title =	{{Design of a WCET-Aware C Compiler}},
  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.2006.673},
  URN =		{urn:nbn:de:0030-drops-6733},
  doi =		{10.4230/OASIcs.WCET.2006.673},
  annote =	{Keywords: WCET, compiler, multi-objective, intermediate representation, ICD-C, LLIR, CRL2, aiT}
}
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