Volume
OASIcs, Volume 15
10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)
-
Part of:
Series:
Open Access Series in Informatics (OASIcs)
Conference: Workshop on Worst-Case Execution Time Analysis (WCET)
Event
WCET 2010, July 6, 2010, Brussels, BelgiumEditor
Publication Details
- published at: 2010-11-26
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-939897-21-7
- DBLP: db/conf/wcet/wcet2010
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Document
Complete Volume
OASIcs, Volume 15, WCET'10, Complete Volume
Abstract
OASIcs, Volume 15, WCET'10, Complete Volume
Cite as
10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)
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@Proceedings{lisper:OASIcs.WCET.2010,
title = {{OASIcs, Volume 15, WCET'10, Complete Volume}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
series = {Open Access Series in Informatics (OASIcs)},
ISBN = {978-3-939897-21-7},
ISSN = {2190-6807},
year = {2012},
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},
URN = {urn:nbn:de:0030-drops-35771},
doi = {10.4230/OASIcs.WCET.2010},
annote = {Keywords: Performance of Systems, Software/Program Verification, Computers in Other Systems}
}
Document
Front Matter
Frontmatter, Preface, Table of Contents, Workshop Organization
Abstract
Frontmatter, Preface, Table of Contents, Workshop Organization.
Cite as
10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. i-ix, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{lisper:OASIcs.WCET.2010.i,
author = {Lisper, Bj\"{o}rn},
title = {{Frontmatter, Preface, Table of Contents, Workshop Organization}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {i--ix},
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.i},
URN = {urn:nbn:de:0030-drops-28195},
doi = {10.4230/OASIcs.WCET.2010.i},
annote = {Keywords: Frontmatter, Preface, Table of Contents, Workshop Organization}
}
Document
Timing Anomalies Reloaded
Abstract
Computing tight WCET bounds in the presence of timing anomalies - found in almost any modern hardware architecture - is a major challenge of timing analysis.
In this paper, we renew the discussion about timing anomalies, demonstrating that even simple hardware architectures are prone to timing anomalies. We furthermore complete the list of timing-anomalous cache replacement policies, proving that the most-recently-used replacement policy (MRU) also exhibits a domino effect.
Cite as
Gernot Gebhard. Timing Anomalies Reloaded. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 1-10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{gebhard:OASIcs.WCET.2010.1,
author = {Gebhard, Gernot},
title = {{Timing Anomalies Reloaded}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {1--10},
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.2010.1},
URN = {urn:nbn:de:0030-drops-28201},
doi = {10.4230/OASIcs.WCET.2010.1},
annote = {Keywords: Timing Anomalies, Domino Effects, MRU Replacement Policy, LEON2}
}
Document
Bounding the Effects of Resource Access Protocols on Cache Behavior
Abstract
The assumption of task independence has long been consubstantial with the formulation of many schedulability analysis techniques. That assumption is evidently advantageous for the mathematical formulation of the analysis equations, but ill fit to capture the actual behavior of the system. Resource sharing is one of the system design dimensions that break the assumption of task independence. By shaking the very foundations of the real-time analysis theory, the advent of multicore systems has caused resurgence of interest in resource sharing and synchronization protocols, and also dawned the fact that the assumption of task independence may be forever broken. Research in cache-aware schedulability analysis instead has paid very little attention to the impact that synchronization protocols may have on cache behavior. A blocked task may in fact incur time penalties similar in kind to those caused by preemption, in that some useful code or data already loaded in the cache may be evicted while the task is blocked. In this paper we characterize the sources of cache-related blocking delay (CRBD). We then provide a bound on the CRBD for three synchronization protocols of interest. The comparison between these bounds provides striking evidence that an informed choice of the synchronization protocol helps contain the perturbing effects of blocking on the cache state.
Cite as
Enrico Mezzetti, Marco Panunzio, and Tullio Vardanega. Bounding the Effects of Resource Access Protocols on Cache Behavior. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 11-22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{mezzetti_et_al:OASIcs.WCET.2010.11,
author = {Mezzetti, Enrico and Panunzio, Marco and Vardanega, Tullio},
title = {{Bounding the Effects of Resource Access Protocols on Cache Behavior}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {11--22},
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.2010.11},
URN = {urn:nbn:de:0030-drops-28217},
doi = {10.4230/OASIcs.WCET.2010.11},
annote = {Keywords: Resource access protocols, cache, worst-case response time}
}
Document
Toward Precise PLRU Cache Analysis
Abstract
Schedulability analysis for hard real-time systems requires bounds on the execution times of its tasks. To obtain useful bounds in the presence of caches, cache analysis is mandatory.
The subject-matter of this article is the static analysis of the tree-based PLRU cache replacement policy (pseudo least-recently used), for which the precision of analyses lags behind those of other policies. We introduce the term subtree distance, which is important for the update behavior of PLRU and closely linked to the peculiarity of PLRU that allows cache contents to be evicted in "logarithmic time". Based on an abstraction of subtree distance, we define a must-analysis that is more precise than prior ones by excluding spurious logarithmic-time eviction.
Cite as
Daniel Grund and Jan Reineke. Toward Precise PLRU Cache Analysis. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 23-35, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{grund_et_al:OASIcs.WCET.2010.23,
author = {Grund, Daniel and Reineke, Jan},
title = {{Toward Precise PLRU Cache Analysis}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {23--35},
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.2010.23},
URN = {urn:nbn:de:0030-drops-28226},
doi = {10.4230/OASIcs.WCET.2010.23},
annote = {Keywords: Cache Analysis, PLRU Replacement, PLRU Tree}
}
Document
Integrating Abstract Caches with Symbolic Pipeline Analysis
Abstract
Static worst-case execution time analysis of real-time tasks is based on abstract models that capture the timing behavior of the processor on which the tasks run. For complex processors, task-level execution time bounds are obtained by a state space exploration which involves the abstract model and the program. Partial state space exploration is not sound. Symbolic methods using binary decision diagrams (BDDs) allow for a full state space exploration of the pipeline, thereby maintaining soundness. Caches are too large to admit an efficient BDD representation. On the other hand, invariants of the cache state can be computed efficiently using abstract interpretation. How to integrate abstract caches with symbolic-state pipeline analysis is an open question. We propose a semi-symbolic domain to solve this problem. Statistical data from industrial-level software and WCET tools indicate that this new domain will enable an efficient analysis.
Cite as
Stephan Wilhelm and Christoph Cullmann. Integrating Abstract Caches with Symbolic Pipeline Analysis. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 36-43, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{wilhelm_et_al:OASIcs.WCET.2010.36,
author = {Wilhelm, Stephan and Cullmann, Christoph},
title = {{Integrating Abstract Caches with Symbolic Pipeline Analysis}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {36--43},
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.2010.36},
URN = {urn:nbn:de:0030-drops-28235},
doi = {10.4230/OASIcs.WCET.2010.36},
annote = {Keywords: WCET analysis, cache analysis, pipeline analysis}
}
Document
Realism in Statistical Analysis of Worst Case Execution Times
Abstract
This paper considers the use of Extreme Value Theory (EVT) to model worst-case execution times. In particular it considers the sacrifice that statistical methods make in the realism of their models in order to provide generality and precision, and if the sacrifice of realism can impact the safety of the model. The Gumbel distribution is assessed in terms of its assumption of continuous behaviour and its need for independent and identically distributed data. To ensure that predictions made by EVT estimations are safe, additional restrictions on their use are proposed and justified.
Cite as
David Griffin and Alan Burns. Realism in Statistical Analysis of Worst Case Execution Times. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 44-53, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{griffin_et_al:OASIcs.WCET.2010.44,
author = {Griffin, David and Burns, Alan},
title = {{Realism in Statistical Analysis of Worst Case Execution Times}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {44--53},
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.2010.44},
URN = {urn:nbn:de:0030-drops-28245},
doi = {10.4230/OASIcs.WCET.2010.44},
annote = {Keywords: WCET, Extreme value statistics, Gumbel distribution}
}
Document
Hybrid measurement-based WCET analysis at the source level using object-level traces
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
On the Use of Context Information for Precise Measurement-Based Execution Time Estimation
Abstract
The present paper investigates the influence of the execution history on the precision of measurement-based execution time estimates for embedded software. A new approach to timing analysis is presented which was designed to overcome the problems of existing static and dynamic methods. By partitioning the analyzed programs into easily traceable segments and by precisely controlling run-time measurements with on-chip tracing facilities, the new method is able to preserve information about the execution context of measured execution times. After an adequate number of measurements have been taken, this information can be used to precisely estimate the Worst-Case Execution Time of a program without being overly pessimistic.
Cite as
Stefan Stattelmann and Florian Martin. On the Use of Context Information for Precise Measurement-Based Execution Time Estimation. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 64-76, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{stattelmann_et_al:OASIcs.WCET.2010.64,
author = {Stattelmann, Stefan and Martin, Florian},
title = {{On the Use of Context Information for Precise Measurement-Based Execution Time Estimation}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {64--76},
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.2010.64},
URN = {urn:nbn:de:0030-drops-28269},
doi = {10.4230/OASIcs.WCET.2010.64},
annote = {Keywords: WCET analysis, trace, execution time measurement}
}
Document
A Code Policy Guaranteeing Fully Automated Path Analysis
Abstract
Calculating the worst-case execution time (WCET) of real-time tasks is still a tedious job. Programmers are required to provide additional information on the program flow, analyzing subtle, context dependent loop bounds manually. In this paper, we propose to restrict written and generated code to the class of programs with input-data independent loop counters. The proposed policy builds on the ideas of single-path code, but only requires partial input-data independence. It is always possible to find precise loop bounds for these programs, using an efficient variant of abstract execution. The systematic construction of tasks following the policy is facilitated by embedding knowledge on input-data dependence in function interfaces and types. Several algorithms and benchmarks are analyzed to show that this restriction is indeed a good candidate for removing the need for manual annotations.
Cite as
Benedikt Huber and Peter Puschner. A Code Policy Guaranteeing Fully Automated Path Analysis. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 77-88, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{huber_et_al:OASIcs.WCET.2010.77,
author = {Huber, Benedikt and Puschner, Peter},
title = {{A Code Policy Guaranteeing Fully Automated Path Analysis}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {77--88},
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.2010.77},
URN = {urn:nbn:de:0030-drops-28274},
doi = {10.4230/OASIcs.WCET.2010.77},
annote = {Keywords: WCET analysis, path analysis, single-path code, SSA form}
}
Document
WCET Computation of Safety-Critical Avionics Programs: Challenges, Achievements and Perspectives
Abstract
Time-critical avionics software products must compute their output in due time. If it is not the case, the safety of the avionics systems to which they belong might be affected. Consequently, the Worst Case Excution Time of the tasks of such programs must be computed safely, i.e., they must not be under-estimated. Since computing the exact WCET of a real-size software product task is not possible (undecidability), "safe WCET" means over-estimated WCET. Here we have an industrial issue in the sense that too over-estimating the WCET leads to a waste of CPU power. Hence, the computation a safe and precise WCET is the big challenge. Solutions to that problem cannot only rely on the technique for computing the WCET. Indeed, both hardware and software must be designed to be as deterministic as possible. For its Flight controls software products, Airbus has always been applying these principles but, since the A380, the use of more complex processors required to move from a technique based on measurements to a new one based on static analysis by Abstract Interpretation. Another kind of avionics applications are the so-called High-performance avionics software products, which are significantly less affected by - rare - delays in the computation of their outputs. In this case, the need for a "safe WCET" is less strong, hence opening the door to different other ways of computing it. In this context, the aim of the talk is to present the challenge of computing WCET in Airbus's industrial context, the achievements in this field and the evocation of some trends and perspectives.
Cite as
Jean Souyris. WCET Computation of Safety-Critical Avionics Programs: Challenges, Achievements and Perspectives. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, p. 89, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{souyris:OASIcs.WCET.2010.89,
author = {Souyris, Jean},
title = {{WCET Computation of Safety-Critical Avionics Programs: Challenges, Achievements and Perspectives}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {89--89},
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.2010.89},
URN = {urn:nbn:de:0030-drops-28284},
doi = {10.4230/OASIcs.WCET.2010.89},
annote = {Keywords: WCET analysis, avionics software, safety-critical system}
}
Document
WCET Analysis of a Parallel 3D Multigrid Solver Executed on the MERASA Multi-Core
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
Towards WCET Analysis of Multicore Architectures Using UPPAAL
Abstract
To take full advantage of the increasingly used shared-memory multicore architectures, software algorithms will need to be parallelized over multiple threads. This means that threads will have to share resources (e.g. some level of cache) and communicate and synchronize with each other. There already exist software libraries (e.g. OpenMP) used to explicitly parallelize available sequential C/C++ and Fortran code, which means that parallel code could be easily obtained.
To be able to use parallel software running on multicore architectures in embedded systems with hard real-time constraints, new WCET (Worst-Case Execution Time) analysis methods and tools must be developed. This paper investigates a method based on model-checking a system of timed automata using the UPPAAL tool box. It is found that it is possible to perform WCET analysis on (small) parallel systems using UPPAAL. We also show how to model thread synchronization using spinlock-like primitives.
Cite as
Andreas Gustavsson, Andreas Ermedahl, Björn Lisper, and Paul Pettersson. Towards WCET Analysis of Multicore Architectures Using UPPAAL. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 101-112, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{gustavsson_et_al:OASIcs.WCET.2010.101,
author = {Gustavsson, Andreas and Ermedahl, Andreas and Lisper, Bj\"{o}rn and Pettersson, Paul},
title = {{Towards WCET Analysis of Multicore Architectures Using UPPAAL}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {101--112},
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.2010.101},
URN = {urn:nbn:de:0030-drops-28304},
doi = {10.4230/OASIcs.WCET.2010.101},
annote = {Keywords: WCET, Multicore, Parallel, Thread Synchronization, Model-Checking, UPPAAL}
}
Document
METAMOC: Modular Execution Time Analysis using Model Checking
Abstract
Safe and tight worst-case execution times (WCETs) are important when scheduling hard real-time systems. This paper presents METAMOC, a modular method, based on model checking and static analysis, that determines safe and tight WCETs for programs running on platforms featuring caching and pipelining. The method works by constructing a UPPAAL model of the program being analysed and annotating the model with information from an inter-procedural value analysis. The program model is then combined with a model of the hardware platform and model checked for the WCET. Through support for the platforms ARM7, ARM9 and ATMEL AVR 8-bit, the modularity and retargetability of the method are demonstrated, as only the pipeline needs to be remodelled. Hardware modelling is performed in a state-of-the-art graphical modelling environment. Experiments on the Mälardalen WCET benchmark programs show that taking caching into account yields much tighter WCETs than without modelling caches, and that METAMOC is a sufficiently fast and versatile approach for WCET analysis.
Cite as
Andreas E. Dalsgaard, Mads Chr. Olesen, Martin Toft, René Rydhof Hansen, and Kim Guldstrand Larsen. METAMOC: Modular Execution Time Analysis using Model Checking. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 113-123, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{dalsgaard_et_al:OASIcs.WCET.2010.113,
author = {Dalsgaard, Andreas E. and Olesen, Mads Chr. and Toft, Martin and Hansen, Ren\'{e} Rydhof and Larsen, Kim Guldstrand},
title = {{METAMOC: Modular Execution Time Analysis using Model Checking}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {113--123},
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.2010.113},
URN = {urn:nbn:de:0030-drops-28319},
doi = {10.4230/OASIcs.WCET.2010.113},
annote = {Keywords: WCET analysis, timed automata, model checking, UPPAAL}
}
Document
Precomputing Memory Locations for Parametric Allocations
Abstract
Current worst-case execution time (WCET) analyses do not support programs using dynamic memory allocation. This is mainly due to the unpredictability of cache performance introduced by standard memory allocators. To overcome this problem, algorithms have been proposed that precompute static allocations for dynamically allocating programs with known numeric bounds on the number and sizes of allocated memory blocks. In this paper, we present a novel algorithm for computing such static allocations that can cope with parametric bounds on the number and sizes of allocated blocks. To demonstrate the usefulness of our approach, we precompute static allocations or a set of existing real-time applications and academic examples.
Cite as
Jörg Herter and Sebastian Altmeyer. Precomputing Memory Locations for Parametric Allocations. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 124-135, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{herter_et_al:OASIcs.WCET.2010.124,
author = {Herter, J\"{o}rg and Altmeyer, Sebastian},
title = {{Precomputing Memory Locations for Parametric Allocations}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {124--135},
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.2010.124},
URN = {urn:nbn:de:0030-drops-28320},
doi = {10.4230/OASIcs.WCET.2010.124},
annote = {Keywords: WCET analysis, cache analysis, dynamic/static memory allocation}
}
Document
The Mälardalen WCET Benchmarks: Past, Present And Future
Abstract
Modelling of real-time systems requires accurate and tight estimates of the Worst-Case Execution Time (WCET) of each task scheduled to run. In the past two decades, two main paradigms have emerged within the field of WCET analysis: static analysis and hybrid measurement-based analysis. These techniques have been succesfully implemented in prototype and commercial toolsets. Yet, comparison among the WCET estimates derived by such tools remains somewhat elusive as it requires a common set of benchmarks which serve a multitude of needs.
The Maelardalen WCET research group maintains a large number of WCET benchmark programs for this purpose. This paper describes properties of the existing benchmarks, including their relative strengths and weaknesses. We propose extensions to the benchmarks which will allow any type of WCET tool evaluate its results against other state-of-the-art tools, thus setting a high standard for future research and development.
We also propose an organization supporting the future work with the benchmarks. We suggest to form a committee with a responsibility for the benchmarks, and that the benchmark web site is transformed to an open wiki, with possibility for the WCET community to easily update the benchmarks.
Cite as
Jan Gustafsson, Adam Betts, Andreas Ermedahl, and Björn Lisper. The Mälardalen WCET Benchmarks: Past, Present And Future. In 10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010). Open Access Series in Informatics (OASIcs), Volume 15, pp. 136-146, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)
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@InProceedings{gustafsson_et_al:OASIcs.WCET.2010.136,
author = {Gustafsson, Jan and Betts, Adam and Ermedahl, Andreas and Lisper, Bj\"{o}rn},
title = {{The M\"{a}lardalen WCET Benchmarks: Past, Present And Future}},
booktitle = {10th International Workshop on Worst-Case Execution Time Analysis (WCET 2010)},
pages = {136--146},
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.2010.136},
URN = {urn:nbn:de:0030-drops-28336},
doi = {10.4230/OASIcs.WCET.2010.136},
annote = {Keywords: WCET analysis, benchmark}
}