Measurement-Based Timing Analysis

Wenzel, Ingomar; Kirner, Raimund; Rieder, Bernhard; Puschner, Peter

doi:10.1007/978-3-540-88479-8_30

Cited by 59 publications

(40 citation statements)

References 9 publications

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“…Measurement-based timing analysis is a common practice for timing analysis on real processors in industrial domains that include space, automotive and elements of avionics [34], [17], [20]. End-to-end measurements are collected in controlled conditions and the ETB is derived by adding an engineering margin to the Longest Observed Execution Time (LOET) [20].…”

Section: Deriving Etb Under Different Contention Conditionsmentioning

confidence: 99%

Seeking Time-Composable Partitions of Tasks for COTS Multicore Processors

Fernández

Abella

Quiñones

et al. 2015

2015 IEEE 18th International Symposium on Real-Time Distributed Computing

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Abstract-The timing verification of real-time singlecore systems involves a timing analysis step that yields an Execution Time Bound (ETB) for each task, followed by a schedulability analysis step, where the scheduling attributes of the individual tasks, including the ETB, are studied from the system level perspective. The transition between those two steps involves accounting for the interference effects that arise when tasks contend for access to shared resource. The advent of multicore processors challenges the viability of this two-step approach because several complex contention effects at the processor level arise that cause tasks to be unable to make progress while actually holding the CPU, which are very difficult to tightly capture by simply inflating the tasks' ETB. In this paper we show how contention on access to hardware shared resources creates a circular dependence between the determination of tasks' ETB and their scheduling at run time. To help loosen this knot we present an approach that acknowledges different flavors of time composability, examining in detail the variant intended for partitioned scheduling, which we evaluate on two real processor boards used in the space domain.

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Section: Deriving Etb Under Different Contention Conditionsmentioning

confidence: 99%

Seeking Time-Composable Partitions of Tasks for COTS Multicore Processors

Fernández

Abella

Quiñones

et al. 2015

2015 IEEE 18th International Symposium on Real-Time Distributed Computing

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“…Consequently, various solutions for the low-level analysis of individual path fragments in the presence of caches, pipelines, and branch predictors were proposed (Li and Malik 1999;Lundqvist andStenström 1998, 1999;Stappert and Altenbernd 2000;Theiling and Ferdinand 1998;Schneider and Ferdinand 1999;Ferdinand et al 1999;Colin and Puaut 2000). In contrast to these model-based approach, measurement-based timing analysis (MBTA) proposed the use of timed execution traces of individual code constituents obtained runs of the code on the target hardware (Bernat et al 2002(Bernat et al , 2003Kirner et al 2005;Wenzel et al 2009;Stattelmann and Martin 2010). …”

Section: Related Workmentioning

confidence: 99%

“…Measurement-based timing analysis (MBTA) (Bernat et al 2002(Bernat et al , 2003Kirner et al 2005;Wenzel et al 2009;Stattelmann and Martin 2010) proposes the calculation of WCET estimates from a database of timed execution traces of code runs on the target hardware. Furthermore, many analysis tool chains rely on the Implicit Path Enumeration Technique (IPET) (Li and Malik 1995;Puschner and Schedl 1997;Li and Malik 1997) to calculate a global WCET estimate from WCET estimates of individual code constituents.…”

Section: Introductionmentioning

confidence: 99%

Calculating WCET estimates from timed traces

Zolda

Kirner

2015

Real-Time Syst

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Real-time systems engineers face a daunting duty: they must ensure that each task in their system can always meet its deadline. To analyse schedulability they must know the worst-case execution time (WCET) of each task. However, determining exact WCETs is practically infeasible in cost-constrained industrial settings involving real-life code and COTS hardware. Static analysis tools that could yield sufficiently tight WCET bounds are often unavailable. As a result, interest in portable analysis approaches like measurement-based timing analysis is growing. We present an approach based on integer linear programming (ILP) for calculating a WCET estimate from a given database of timed execution traces. Unlike previous work, our method specifically aims at reducing overestimation, by means of an automatic classification of code executions into scenarios with differing worst-case behaviour. To ease the integration into existing analysis tool chains, our method is based on the implicit path enumeration technique. It can thus reuse flow facts from other analysis tools and produces ILP problems that can be solved by off-the-shelf solvers.

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“…For example, the pWCET tool of Bernat et al [4] uses relatively fine-grained scoping, down to the basic-block level. In contrast, the philosophy of the MTime tool is to use a relatively coarse-grained scoping to reduce measurement error [67]. MTime is looking for a tradeoff between the maximum code length covered by sub-paths and the number of sub-paths to be measured.…”

Section: Epet (Path-oriented)mentioning

confidence: 99%

“…There are static WCET analysis approaches [18,58] and measurement-based timing analysis approaches [67,69] based on EPET.…”

Section: Epet (Path-oriented)mentioning

confidence: 99%

Beyond loop bounds: comparing annotation languages for worst-case execution time analysis

et al. 2010

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Worst-case execution time (WCET) analysis is concerned with computing a precise-as-possible bound for the maximum time the execution of a program can take. This information is indispensable for developing safety-critical real-time systems, e. g., in the avionics and automotive fields. Starting with the initial works of Chen, Mok, Puschner, Shaw, and others in the mid and late 1980s, WCET analysis turned into a well-established and vibrant field of research and development in academia and industry. The increasing number and diversity of hardware and software platforms and the ongoing rapid technological advancement became drivers for the development of a wide array of distinct methods and tools for WCET analysis. The precision, generality, and efficiency of these methods and tools depend much on the expressiveness and usability of the annotation languages that are used to describe feasible and infeasible program paths. In this article we survey the annotation languages which we consider formative for the field. By investigating and comparing their individual strengths and limitations with respect to a set of pivotal criteria, we provide a coherent overview of the state of the art. Identifying open issues, we encourage further research. This way, our approach is orthogonal and complementary to a recent approach of Wilhelm et al. who provide a thorough survey of WCET analysis methods and tools that have been developed and used in academia and industry.Keywords Worst-case execution time (WCET) analysis · Annotation languages · Path-oriented, constraint-oriented, and hierarchy-oriented WCET annotation languages · WCET annotation language challenge MotivationComputing the time that the execution of a program can take in the worst case is challenging. It requires to cope with analysis problems that are computationally intractable or undecidable. Tools and methods for worst-case execution time analysis (WCET) thus usually content themselves to computing an upper bound of the actual WCET. The precision, generality, and efficiency of these tools and methods depend much on the accurate description and identification of feasible and infeasible program paths. A program path is feasible, 123 412 R. Kirner et al. if there is an actual program execution taking this path; it is infeasible otherwise. In practice, this information is computed by fully automatic program analyses, where possible; it is manually provided by application programmers otherwise. In both cases this requires a dedicated language in order to annotate this information and to pass it on to a subsequent WCET analysis. Such a language is commonly called an annotation language. Over the past two decades, an array of conceptually quite diverse annotation languages has been proposed to support the needs of different WCET analysis methods and tools.In this article, we present a systematic and comprehensive comparison of the various approaches for WCET annotation languages. This acts on our suggestion of the WCET annotation language challenge [32] comple...

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Measurement-Based Timing Analysis

Cited by 59 publications

References 9 publications

Seeking Time-Composable Partitions of Tasks for COTS Multicore Processors

Seeking Time-Composable Partitions of Tasks for COTS Multicore Processors

Calculating WCET estimates from timed traces

Beyond loop bounds: comparing annotation languages for worst-case execution time analysis

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