Survey on Periodic Scheduling for Time-triggered Hard Real-time Systems

2021 ◽  
Vol 54 (1) ◽  
pp. 1-32
Author(s):  
Anna Minaeva ◽  
Zdeněk Hanzálek

This survey covers the basic principles and related works addressing the time-triggered scheduling of periodic tasks with deadlines. The wide range of applications and the increasing complexity of modern real-time systems result in the continually growing interest in this topic. However, the articles in this field appear without systematic notation. To address it, we extend the three-field Graham notation to cover periodic scheduling. Moreover, we formally define three example periodic scheduling problems (PSPs) and provide straightforward implementations of these examples in the Satisfiability Modulo Theories formalism with source codes. Then, we present a summary of the complexity results containing existing polynomially solvable PSPs. We also provide an overview of simple state-of-the-art methods and tricks to solve the PSPs efficiently in terms of time. Next, we survey the existing works on PSP according to the resource environment: scheduling on a single resource, on parallel identical resources, and on dedicated resources. In the survey, we indicate which works propose solution methods for more general PSPs. Finally, we present related problems that are not periodic by nature to provide inspiration for the PSP solution.

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Mathieu Côté ◽  
Michel R. Dagenais

This paper focuses on the analysis of execution traces for real-time systems. Kernel tracing can provide useful information, without having to instrument the applications studied. However, the generated traces are often very large. The challenge is to retrieve only relevant data in order to find quickly complex or erratic real-time problems. We propose a new approach to help finding those problems. First, we provide a way to define the execution model of real-time tasks with the optional suggestions of a pattern discovery algorithm. Then, we show the resulting real-time jobs in a Comparison View, to highlight those that are problematic. Once some jobs that present irregularities are selected, different analyses are executed on the corresponding trace segments instead of the whole trace. This allows saving huge amount of time and execute more complex analyses. Our main contribution is to combine the critical path analysis with the scheduling information to detect scheduling problems. The efficiency of the proposed method is demonstrated with two test cases, where problems that were difficult to identify were found in a few minutes.


2011 ◽  
Vol 179-180 ◽  
pp. 220-225
Author(s):  
Jie Li ◽  
Rui Feng Guo ◽  
Zhi Xiang Shao

Task scheduling is an important research topic of real-time systems. Compared with the common real-time systems, CNC system has its own features. In this paper, we propose an adaptive task scheduling model for CNC system and analyze its schedulability. The model is suitable to the uncertainty of open computing environment and can accept the running of different types of tasks. It can compute band changes according to the latest changes of system resources and task requirements. It adjusts tasks’ priorities adaptively and makes the system run in optimal real-time performance. On the basis of CNC system, we will further optimize the model by studying the characteristics of periodic tasks and scheduling time overhead. Finally, this model will be used in practical CNC system.


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