eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
0
0
10.4230/OASIcs.WCET.2012
article
OASIcs, Volume 23, WCET'12, Complete Volume
Vardanega, Tullio
OASIcs, Volume 23, WCET'12, Complete Volume
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012/OASIcs.WCET.2012.pdf
[Special-Purpose and Application-Based Systems]: Real-time and embedded systems, [Performance of systems]: Modelling techniques, Performance attribute Software/Program Verification, Testing and Debugging, [Software Engineering]: Software Architectures – Domain-specific architectures, Patterns
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
i
xi
10.4230/OASIcs.WCET.2012.i
article
Frontmatter, Table of Contents, Preface, Workshop Organization, List of Authors
Vardanega, Tullio
Frontmatter, Table of Contents, Preface, Workshop Organization, List of Authors
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.i/OASIcs.WCET.2012.i.pdf
Frontmatter
Table of Contents
Preface
Workshop Organization
List of Authors
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
1
12
10.4230/OASIcs.WCET.2012.1
article
What is a Timing Anomaly?
Cassez, Franck
Hansen, René Rydhof
Olesen, Mads Chr.
Timing anomalies make worst-case execution time analysis much harder, because the analysis will have to consider all local choices. It has been widely recognised that certain hardware features are timing anomalous, while others are not. However, defining formally what a timing anomaly is, has been difficult.
We examine previous definitions of timing anomalies, and identify examples where they do not align with common observations. We then provide a definition for consistently slower hardware traces that can be used to define timing anomalies and aligns with common observations.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.1/OASIcs.WCET.2012.1.pdf
Timing anomalies
worst case execution time (WCET)
abstractions
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
13
24
10.4230/OASIcs.WCET.2012.13
article
An Empirical Evaluation of the Influence of the Load-Store Unit on WCET Analysis
Abdel Maksoud, Mohamed
Reineke, Jan
Due to the complexity of today’s micro-architectures, the micro-architectural analysis usually constitutes the most time-consuming step in worst-case execution time (WCET) analysis.
In this paper, we investigate the influence of the design of the load-store unit (LSU) in the PowerPC 7448 on WCET analysis. To this end, we introduce a simplified variant of the existing design of the LSU by reducing its queue sizes. Using AbsInt's aiT WCET analysis toolchain we determine the resulting WCET bounds and analysis times.
For the modified version of the LSU with reduced queue sizes, analysis time is reduced by more than 50% on a set of benchmarks from the Mälardalen suite, while there is little change in the WCET bound.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.13/OASIcs.WCET.2012.13.pdf
Empirical evaluation
architecture complexity effect
WCET analysis precision
WCET analysis performance
PowerPC 7448
Load-Store Unit
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
25
37
10.4230/OASIcs.WCET.2012.25
article
Computing Same Block Relations for Relational Cache Analysis
Wegener, Simon
In contrast to the classical cache analysis of Ferdinand, the relational cache analysis does not rely on precise address information. Instead, it uses same block relations between memory accesses to predict cache hits. The relational data cache analysis can thus also predict cache hits if fully unrolling a loop is not feasible during analysis, for example due to high memory consumption or long computation time. This paper proposes a static analysis based on abstract interpretation which is able to compute same block relations for relational cache analysis.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.25/OASIcs.WCET.2012.25.pdf
Cache Analysis
WCET Analysis
Real-time Systems
Static Program Analysis
Abstract Interpretation
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
38
47
10.4230/OASIcs.WCET.2012.38
article
Toward Static Timing Analysis of Parallel Software
Gustavsson, Andreas
Gustafsson, Jan
Lisper, Björn
The current trend within computer, and even real-time, systems is to incorporate parallel hardware, e.g., multicore processors, and parallel software. Thus, the ability to safely analyse such parallel systems, e.g., regarding the timing behaviour, becomes necessary. Static timing analysis is an approach to mathematically derive safe bounds on the execution time of a program, when executed on a given hardware platform. This paper presents an algorithm that statically analyses the timing of parallel software, with threads communicating through shared memory, using abstract interpretation. It also gives an extensive example to clarify how the algorithm works.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.38/OASIcs.WCET.2012.38.pdf
Parallelism
BCET
WCET
Static analysis
Abstract interpretation
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
48
58
10.4230/OASIcs.WCET.2012.48
article
Towards Parallel Programming Models for Predictability
Lisper, Björn
Future embedded systems for performance-demanding applications will be massively parallel. High performance tasks will be parallel programs, running on several cores, rather than single threads running on single cores. For hard real-time applications, WCETs for such tasks must be bounded. Low-level parallel programming models, based on concurrent threads, are notoriously hard to use due to their inherent nondeterminism. Therefore the parallel processing community
has long considered high-level parallel programming models, which restrict the low-level models to regain determinism. In this position paper we argue that such parallel programming models are beneficial also for WCET analysis of parallel programs. We review some proposed models, and discuss their influence on timing predictability. In particular we identify data parallel programming as a suitable paradigm as it is deterministic and allows current methods for WCET
analysis to be extended to parallel code. GPUs are increasingly used for high performance applications: we discuss a current GPU architecture, and we argue that it offers a parallel platform
for compute-intensive applications for which it seems possible to construct precise timing models. Thus, a promising route for the future is to develop WCET analyses for data-parallel software running on GPUs.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.48/OASIcs.WCET.2012.48.pdf
Real-Time System
WCET analysis
Parallel Program
Data Parallelism
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
59
68
10.4230/OASIcs.WCET.2012.59
article
Timing Analysis of Concurrent Programs
Mittermayr, Robert
Blieberger, Johann
Worst-case execution time analysis of multi-threaded software is still a challenge. This comes mainly from the fact that the number of thread interleavings grows exponentially in the number of threads and that synchronization has to be taken into account. In particular, a suitable graph based model has been missing. The idea that thread interleavings can be studied with a matrix calculus is a novel approach in this research area. Our sparse matrix representations
of the program are manipulated using Kronecker algebra. The resulting graph represents the multi-threaded program and plays a similar role for concurrent systems as control flow graphs do for sequential programs. Thus a suitable graph model for timing analysis of multi-threaded software has been set up. Due to synchronization it turns out that often only very small parts of the resulting graph are actually needed, whereas the rest is unreachable. A lazy implementation of the matrix operations ensures that the unreachable parts are never calculated. This speeds up processing significantly and shows that our approach is very promising.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.59/OASIcs.WCET.2012.59.pdf
Worst-case execution time analysis (WCET)
Concurrency
Thread Synchronization
Kronecker Algebra
Program Analysis
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
69
80
10.4230/OASIcs.WCET.2012.69
article
A Time-composable Operating System
Baldovin, Andrea
Mezzetti, Enrico
Vardanega, Tullio
Time composability is a guiding principle to the development and certification process of real-time embedded systems. Considerable efforts have been devoted to studying the role of hardware
architectures - and their modern accelerating features - in enabling the hierarchical composition of the timing behaviour of software programs considered in isolation. Much less attention has been devoted to the effect of real-time Operating Systems (OS) on time composability at the application level.
In fact, the very presence of the OS contributes to the variability of the execution time of the application directly and indirectly; by way of its own response time jitter and by its effect on the state retained by the processor hardware. We consider zero disturbance and steady behaviour as those characteristic properties that an operating system should exhibit, so as to be time-composable with the user applications. We assess those properties on the redesign of
an ARINC compliant partitioned operating system, for use in avionics applications, and present some experimental results from a preliminary implementation of our approach within the scope
of the EU FP7 PROARTIS project.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.69/OASIcs.WCET.2012.69.pdf
Real-time Operating System
Timing composability
ARINC
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
81
90
10.4230/OASIcs.WCET.2012.81
article
Analysis of WCET in an experimental satellite software development
Garrido, Jorge
Brosnan, Daniel
de la Puente, Juan A.
Alonso, Alejandro
Zamorano, Juan
This paper describes a case study in WCET analysis of an on-board spacecraft software system. The attitude control system of UPMSat-2, an experimental micro-satellite which is scheduled to be launched in 2013, is used for an experiment on analysing the worst-case execution time of code automatically generated from a Simulink model. In order to properly test the code, a hardware-in-the-loop configuration with a simulation model of the spacecraft environment has been used as a test bench. The code has been analysed with RapiTime, with some modifications to the original instrumentation routines, in order to take into account the particularities of the test configuration. Results from the experiment are described and commented in the paper.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.81/OASIcs.WCET.2012.81.pdf
Real-time systems
embedded systems
timing analysis
WCET calculation
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
91
102
10.4230/OASIcs.WCET.2012.91
article
A Formal Framework for Precise Parametric WCET Formulas
Huber, Benedikt
Prokesch, Daniel
Puschner, Peter
Parametric worst-case execution time (WCET) formulas are a valuable tool to estimate the impact of input data properties on the WCET at design time, or to guide scheduling decisions at runtime. Previous approaches to parametric WCET analysis either provide only informal ad-hoc solutions or tend to be rather pessimistic, as they do not take flow constraints other than simple loop bounds into account. We develop a formal framework around path- and frequency expressions, which allow us to reason about execution frequencies of program parts. Starting from a reducible control flow graph and a set of (parametric) constraints, we show how to obtain frequency expressions and refine them by means of sound approximations, which account for
more sophisticated flow constraints. Finally, we obtain closed-form parametric WCET formulas by means of partial evaluation. We developed a prototype, implementing our solution to parametric WCET analysis, and compared existing approaches within our setting. As our framework
supports fine-grained transformations to improve the precision of parametric formulas, it allows to focus on important flow relations in order to avoid intractably large formulas.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.91/OASIcs.WCET.2012.91.pdf
Worst-case execution time analysis
parametric WCET analysis
path expressions
frequency expressions
algebraic framework
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2012-07-10
23
103
115
10.4230/OASIcs.WCET.2012.103
article
Evolutionary Techniques for Parametric WCET Analysis
Marref, Amine
Estimating the worst-case execution time (WCET) of real-time programs is pivotal in their verification. WCET estimation either yields a numeric value that represents the maximum execution time of the program when executed on a specific hardware platform; or yields a parametric expression in the form of some function of the input which when instantiated with a particular input value, gives a WCET estimation of the program when triggered by this input specifically
(on a specific hardware platform). Parametric WCET analysis provides extra accuracy as the WCET estimation can be tuned to particular input values at runtime; and is usually of interest to dynamic-scheduling schemes.
In this paper we use genetic programming as an alternative method to approach the problem of parametric WCET analysis. Parametric expressions are captured automatically by the genetic program based on end-to-end executions of the program under analysis. The technique
is complementary to static parametric WCET analysis and more amenable to industrial practice. Experimental evaluation shows that the presented technique computes accurate parametric expression in an almost negligible time.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol023-wcet2012/OASIcs.WCET.2012.103/OASIcs.WCET.2012.103.pdf
Real-time systems
parametric worst-case execution-time analysis
end- to-end testing
genetic programming