Worst-Case Execution Time Aware Compilation Techniques for Real-Time Systems

In this chapter the authors focus on the problem of reconfiguring embedded real-time systems. Such reconfiguration can be decided either off-line to determine if a given application can be run on a different platform, while preserving the timeliness constraints imposed by the application, or on-line, where a reconfiguration should be done to adapt the system to the context of execution or to handle hardware or software faults. The task model considered in this chapter is the classical sporadic task model defined by a Worst Case Execution Time (WCET), a minimum inter-arrival time (also denoted the minimum Period) and a late termination deadline. The authors consider two preemptive scheduling strategies: Fixed Priority highest priority first (FP) and Earliest Deadline First (EDF). They propose a sensitivity analysis to handle reconfiguration issues. Sensitivity analysis aims at determining acceptable deviations from the specifications of a problem due to evolutions in system characteristics (reconfiguration or performance tuning). They present a state of the art for sensitivity analysis in the case of WCETs, Periods and Deadlines reconfigurations and study to what extent sensitivity analysis can be used to decide on the possibility of reconfiguring a system.

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Interactive WCET Prediction with Warning for Timeout Risk

International Journal of Pattern Recognition and Artificial Intelligence ◽

10.1142/s0218001417500124 ◽

2017 ◽

Vol 31 (05) ◽

pp. 1750012 ◽

Cited By ~ 5

Author(s):

Fanqi Meng ◽

Xiaohong Su ◽

Zhaoyang Qu

Keyword(s):

Execution Time ◽

Control Flow ◽

Real Time Systems ◽

Wcet Analysis ◽

Running Speed ◽

Worst Case ◽

Worst Case Execution Time ◽

Level Model ◽

Hard Real Time ◽

Time Systems

Worst case execution time (WCET) analysis is essential for exposing timeliness defects when developing hard real-time systems. However, it is too late to fix timeliness defects cheaply since developers generally perform WCET analysis in a final verification phase. To help developers quickly identify real timeliness defects in an early programming phase, a novel interactive WCET prediction with warning for timeout risk is proposed. The novelty is that the approach not only fast estimates WCET based on a control flow tree (CFT), but also assesses the estimated WCET with a trusted level by a lightweight false path analysis. According to the trusted levels, corresponding warnings will be triggered once the estimated WCET exceeds a preset safe threshold. Hence developers can identify real timeliness defects more timely and efficiently. To this end, we first analyze the reasons of the overestimation of CFT-based WCET calculation; then we propose a trusted level model of timeout risks; for recognizing the structural patterns of timeout risks, we develop a risk data counting algorithm; and we also give some tactics for applying our approach more effectively. Experimental results show that our approach has almost the same running speed compared with the fast and interactive WCET analysis, but it saves more time in identifying real timeliness defects.

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An Overview of Worst-Case Execution Time Estimation for Embedded Programs

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.651-653.624 ◽

2014 ◽

Vol 651-653 ◽

pp. 624-629

Author(s):

Liang Liang Kong ◽

Lin Xiang Shi ◽

Lin Chen

Keyword(s):

Embedded Systems ◽

Real Time ◽

Execution Time ◽

Time Estimation ◽

Worst Case ◽

Performance Metric ◽

Worst Case Execution Time ◽

Hard Real Time ◽

Time Systems

Most embedded systems are real-time systems, so real-time is an important performance metric for embedded systems. The worst-case execution time (WCET) estimation for embedded programs could satisfy the requirement of hard real-time evaluation, so it is widely used in embedded systems evaluation. Based on sufficient survey on the progress of WCET estimation around the world, it proposes a new classification of WCET estimation. After introducing the principle of WCET estimation, it mainly demonstrates various types of technologies to estimate WCET and classifies them into two main streams, namely, static and dynamic WCET estimations. Finally, it shows the development of WCET analysis tools.

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PBench: A Parallel, Real-Time Benchmark Suite

Academic Perspective Procedia ◽

10.33793/acperpro.01.01.37 ◽

2018 ◽

Vol 1 (1) ◽

pp. 178-186 ◽

Cited By ~ 1

Author(s):

Sevil Serttaş ◽

Veysel Harun Şahin

Keyword(s):

Real Time ◽

Execution Time ◽

Matrix Multiplication ◽

Multiprocessor Systems ◽

Time Analysis ◽

Worst Case ◽

Analysis Methods ◽

Worst Case Execution Time ◽

Benchmark Suite ◽

Time Systems

Real-time systems are widely used from the automotive industry to the aerospace industry. The scientists, researchers, and engineers who develop real-time platforms, worst-case execution time analysis methods and tools need to compare their solutions to alternatives. For this purpose, they use benchmark applications. Today many of our computing systems are multicore and/or multiprocessor systems. Therefore, to be able to compare the effectiveness of real-time platforms, worst-case execution time analysis methods and tools, the research community need multi-threaded benchmark applications which scale on multicore and/or multiprocessor systems. In this paper, we present the first version of PBench, a parallel, real-time benchmark suite. PBench includes different types of multi-threaded applications which implement various algorithms from searching to sorting, matrix multiplication to probability distribution calculation. In addition, PBench provides single-threaded versions of all programs to allow side by side comparisons.

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