scholarly journals Beyond the Traditional Analyses and Resource Management in Real-Time Systems

2022 ◽  
pp. 67-77
Author(s):  
Federico Reghenzani
Keyword(s):  
Real Time ◽  
Real Time Systems ◽  
Formal Proofs ◽  
Worst Case ◽  
Worst Case Execution Time ◽  
Quantitative Results ◽  
Real Time Applications ◽  
Hard Real Time ◽  
Phd Thesis ◽  
Time Systems

AbstractThe difficulties in estimating the Worst-Case Execution Time (WCET) of applications make the use of modern computing architectures limited in real-time systems. Critical embedded systems require the tasks of hard real-time applications to meet their deadlines, and formal proofs on the validity of this condition are usually required by certification authorities. In the last decade, researchers proposed the use of probabilistic measurement-based methods to estimate the WCET instead of traditional static methods. In this chapter, we summarize recent theoretical and quantitative results on the use of probabilistic approaches to estimate the WCET presented in the PhD thesis of the author, including possible exploitation scenarios, open challenges, and future directions.

scholarly journals PSO based optimization of worst-case execution time for ASIP application

2018 ◽  
Vol 7 (3.3) ◽  
pp. 252
Author(s):  
Mood Venkanna ◽  
Rameshwar Rao ◽  
P Chandra Sekhar
Keyword(s):  
Real Time ◽  
Upper Bounds ◽  
Real Time Systems ◽  
Worst Case ◽  
Reconfigurable Processor ◽  
Worst Case Execution Time ◽  
Execution Times ◽  
Hard Real Time ◽  
Time Systems ◽  
Time Bounds

Industrial requires hard real-time systems for safety and critical applications like automotive, Aeronautics, manufacturing control and train industries. Hard Real-Time Systems’ embedded controllers are with expectation of complete the tasks within a certain time bounds reliably including task scheduling. The estimation of upper bound limits corresponding to the execution times is often termed as the Worst-Case Execution Times (WCETs). It is an essential step in developing and validating the hard real-time systems. Particularly, the upper bounds need to satisfy these constraints related to the execution times. However, it is often not feasible many times to set upper bounds on execution times for programs. In present work, the problem of choosing reconfigurable Custom Instructions (CIs) is accomplished by optimizing the WCET corresponding to an application. This issue is designed using Particle Swarm Optimization (PSO) based program for a path analysis. The work emphasizes on the effectiveness of optimizing the WCET when applied to a reconfigurable processor. It evaluates a compound application of multimedia with a host of reconfigurable CIs corresponding to a number of hardware parameters.  

Use of Measurements in Worst-Case Execution Time Estimation for Real-Time Systems

2021 ◽  
Author(s):  
Jessica Junia Santillo Costa ◽  
Romulo Silva de Oliveira ◽  
Luis Fernando Arcaro
Keyword(s):  
Real Time ◽  
Execution Time ◽  
Time Estimation ◽  
Real Time Systems ◽  
Worst Case ◽  
Worst Case Execution Time ◽  
Time Systems

scholarly journals Worst-case execution-time analysis for embedded real-time systems

2003 ◽  
Vol 4 (4) ◽  
pp. 437-455 ◽  
Author(s):  
Jakob Engblom ◽  
Andreas Ermedahl ◽  
Mikael Sjödin ◽  
Jan Gustafsson ◽  
Hans Hansson
Keyword(s):  
Real Time ◽  
Execution Time ◽  
Real Time Systems ◽  
Time Analysis ◽  
Worst Case ◽  
Worst Case Execution Time ◽  
Time Systems

Novel prioritized LRU circuits for shared cache in computer systems

2020 ◽  
Vol 34 (23) ◽  
pp. 2050242
Author(s):  
Yao Wang ◽  
Lijun Sun ◽  
Haibo Wang ◽  
Lavanya Gopalakrishnan ◽  
Ronald Eaton
Keyword(s):  
Real Time ◽  
High Performance ◽  
Cmos Technology ◽  
Cache Replacement ◽  
Worst Case ◽  
Shared Cache ◽  
Cache Access ◽  
Worst Case Execution Time ◽  
Real Time Applications ◽  
Time Systems

Cache sharing technique is critical in multi-core and multi-threading systems. It potentially delays the execution of real-time applications and makes the prediction of the worst-case execution time (WCET) of real-time applications more challenging. Prioritized cache has been demonstrated as a promising approach to address this challenge. Instead of the conventional prioritized cache schemes realized at the architecture level by using cache controllers, this work presents two prioritized least recently used (LRU) cache replacement circuits that directly accomplish the prioritization inside the cache circuits, hence significantly reduces the cache access latency. The performance, hardware and power overheads due to the proposed prioritized LRU circuits are investigated based on a 65 nm CMOS technology. It shows that the proposed circuits have very low overhead compared to conventional cache circuits. The presented techniques will lead to more effective prioritized shared cache implementations and benefit the development of high-performance real-time systems.

Reconfiguration of Uniprocessor Sporadic Real-Time Systems

2011 ◽  
pp. 167-189 ◽  
Author(s):  
Laurent George ◽  
Pierre Courbin
Keyword(s):  
Sensitivity Analysis ◽  
Real Time ◽  
Performance Tuning ◽  
Real Time Systems ◽  
Software Faults ◽  
Worst Case ◽  
Task Model ◽  
Worst Case Execution Time ◽  
On Line ◽  
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.

Interactive WCET Prediction with Warning for Timeout Risk

2017 ◽  
Vol 31 (05) ◽  
pp. 1750012 ◽  
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.

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

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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