scholarly journals Probabilistic schedulability analysis for fixed priority mixed criticality real-time systems

2017 ◽  
Author(s):  
Yasmina Abdeddaim ◽  
Dorin Maxim
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Real Time Systems ◽  
Fixed Priority ◽  
Time Systems ◽  
Mixed Criticality

scholarly journals Schedulability Analysis Towards Arbitrarily Activated Tasks in Mixed-Criticality Systems

2017 ◽  
Vol 26 (10) ◽  
pp. 1750159 ◽  
Author(s):  
Biao Hu ◽  
Kai Huang ◽  
Gang Chen ◽  
Long Cheng ◽  
Dongkun Han ◽  
...  
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Real Time Systems ◽  
Activation Patterns ◽  
Task Model ◽  
Efficient Resource ◽  
Task Priority ◽  
Time Systems ◽  
Sufficient Test ◽  
Mixed Criticality

The integration of mixed-critical tasks into a platform is an increasingly important trend in the design of real-time systems due to its efficient resource usage. With a growing variety of activation patterns considered in real-time systems, some of them capture arbitrary activation patterns. As a consequence, the existing scheduling approaches in mixed-criticality systems (MCs), which assume the sporadic tasks with implicit deadlines, have sometimes become inapplicable or are ineffective. In this paper, we extend the sporadically activated task model to the arbitrarily activated task model in MCs with the preemptive fixed-task-priority schedule. By using the event arrival curve to model task activations, we present the necessary and sufficient schedulability tests that are based on the well-established results from Real-Time Calculus. We propose to use the busy-window analysis to do the sufficient test because it has been shown to be tighter than the sufficient test of using Real-Time Calculus. According to our experimental results, for sporadic task sets, our proposed test can achieve the same performance as the state-of-the-art schedulability test. However, compared with the previous schedulability analysis of preemptive fixed-task-priority, our approaches can handle more general tasks with blocking, jitter, and arbitrary deadlines.

scholarly journals Contention-Free Scheduling for Mixed-Criticality Multiprocessor Real-Time System

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1515
Author(s):  
Hyeongboo Baek ◽  
Kilho Lee
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Multiprocessor Systems ◽  
Real Time Systems ◽  
Time System ◽  
Real Time System ◽  
Scheduling Policy ◽  
And Performance ◽  
Time Systems ◽  
Mixed Criticality

Zero-laxity (ZL) and contention-free (CF) policies have received considerable attention owing to their simplicity and applicability to real-time systems equipped with symmetry multiprocessors. Recently, the ZL policy for mixed-criticality (MC) systems has been proposed and studied, but the applicability to and performance of the CF policy for MC systems have not been investigated yet. In this paper, we propose the CF policy (as a scheduling policy) for MC symmetry multiprocessor systems, referred to as the MC systems tailored CF policy (MC-CF), and a schedulability analysis in support thereof. We define the notion of contention-free slots for two different criticalities (of MC systems) of tasks, propose a technique to limit the amount to be utilized for each task by defining an upper bound, and subsequently explain the way in which the contention-free slots are systematically utilized to improve the schedulability of MC symmetry multiprocessor systems. Following this, we develop a deadline analysis (DA) for MC-CF. Using our experimental results under various environmental settings, we demonstrate that MC-CF can significantly improve the schedulability of fixed-priority scheduling.

scholarly journals Using Fixed Priority Pre-emptive Scheduling in Real-Time Systems

2011 ◽  
Vol 6 (1) ◽  
pp. 187 ◽  
Author(s):  
Doina Zmaranda ◽  
Gianina Gabor ◽  
Daniela Elena Popescu ◽  
Codruta Vancea ◽  
Florin Vancea
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Scheduling Algorithms ◽  
Real Time Systems ◽  
Priority Scheduling ◽  
Fixed Priority ◽  
Fixed Priority Scheduling ◽  
Rate Monotonic ◽  
Real Time Applications ◽  
Time Systems

For real-time applications, task scheduling is a problem of paramount importance. Several scheduling algorithms were proposed in the literature, starting from static scheduling or cyclic executives which provide very deterministic yet inflexible behaviour, to the so called best-effort scheduling, which facilitates maximum run-time flexibility but allows only probabilistic predictions of run-time performance presenting a non-predictable and nondeterministic solution. Between these two extremes lies fixed priority scheduling algorithms, such as Rate Monotonic, that is not so efficient for real-time purposes but exhibits a predictable approach because scheduling is doing offline and guarantees regarding process deadlines could be obtained using appropriate analysis methods. This paper investigates the use of Rate Monotonic algorithm by making adjustments in order to make it more suitable for real-time applications. The factors that motivate the interest for fixed priority scheduling algorithms such Rate Monotonic when doing with real-time systems lies in its associated analysis that could be oriented in two directions: schedulability analysis and analysis of process interactions. The analyzing process is carried out using a previously implemented framework that allows modelling, simulation and schedulability analysis for a set of real-time system tasks, and some of the results obtained are presented.

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