Schedulability Analysis of Fixed Priority Servers for Scheduling Aperiodic Real-Time Tasks – A Review

2014 ◽  
Vol 651-653 ◽  
pp. 1933-1936
Author(s):  
Feng Xiang Zhang
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Timing Constraints ◽  
Sporadic Tasks ◽  
Fixed Priority ◽  
Rate Monotonic ◽  
Aperiodic Tasks ◽  
Deadline Monotonic ◽  
Priority Algorithm

This paper focus on the schedulability analysis of fixed priority servers. A number of fixed priority servers and their schedulability analysis are reviewed, these results and properties can be used for constructing systems with different timing constraints, where real-time tasks with hard deadlines and the soft aperiodic tasks can be scheduled in the same system. The aperiodic tasks in the fixed priority servers are not preemptable, and they are scheduled in a first-come first-served manner. There is only one server with many periodic or sporadic tasks in the system. The tasks and the server are scheduled by a fixed priority algorithm such as rate monotonic or deadline monotonic.

A Review of Sufficient Schedulability Analysis for Fixed Priority Scheduling Systems

2015 ◽  
Vol 741 ◽  
pp. 856-859
Author(s):  
Yan Feng Zhai ◽  
Feng Xiang Zhang
Keyword(s):  
Schedulability Analysis ◽  
Priority Assignment ◽  
Priority Scheduling ◽  
Fixed Priority ◽  
Fixed Priority Scheduling ◽  
Rate Monotonic ◽  
Simple Implementation ◽  
Deadline Monotonic ◽  
Activation Rates

This papercarries out a survey of sufficient schedulability analysis forfixed priority (FP) scheduling. The most common used fixed priority assignment is the rate monotonic (RM) algorithm, according to its policy, the task priorities are ordered based on their activation rates, so that the task with the shortest period is assigned the highest priority. However, when each task’s relative deadline is not equal to its period, the RM algorithm is not suitable to assign the task priorities. When relative deadlines are less than or equal to periods,the deadline monotonic (DM) algorithm can be deployed to schedule the tasks. The utilization based schedulability analysis has the advantage of simple implementation, and manyexisting schedulability analyses on uniprocessor are covered.

The Algorithms of Dynamic Servers for Scheduling Aperiodic Real-Time Tasks – A Review

2014 ◽  
Vol 945-949 ◽  
pp. 3380-3383
Author(s):  
Feng Xiang Zhang
Keyword(s):  
Embedded Systems ◽  
Real Time ◽  
Schedulability Analysis ◽  
Periodic Tasks ◽  
Dynamic Algorithms ◽  
Fixed Priority ◽  
Aperiodic Tasks ◽  
Hard Real Time

This paper focus on the dynamic server algorithms, and the servers are used for scheduling soft aperiodic tasks. Many types of servers and their schedulability analysis are reviewed, these properties can be used for constructing hierarchical embedded systems, where the soft aperiodic tasks and the hard real-time tasks can be scheduled in the same system. The aperiodic tasks in the server are not preemptable, and they are executed in a first-come first-served (FCFS) manner. If it is not specified, there is only one server in the system, and rest of the processes in the system are ordinary periodic tasks. The servers could be scheduled by fixed priority or dynamic algorithms.

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.

scholarly journals Limited Non-Preemptive EDF Scheduling for a Real-Time System with Symmetry Multiprocessors

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 172 ◽  
Author(s):  
Hoyoun Lee ◽  
Jinkyu Lee
Keyword(s):  
Real Time ◽  
Scheduling Algorithm ◽  
Schedulability Analysis ◽  
Timing Constraints ◽  
Limited Information ◽  
Time System ◽  
Real Time System ◽  
System A ◽  
The Future ◽  
Earliest Deadline

In a real-time system, a series of jobs invoked by each task should finish its execution before its deadline, and EDF (Earliest Deadline First) is one of the most popular scheduling algorithms to meet such timing constraints of a set of given tasks. However, EDF is known to be ineffective in meeting timing constraints for non-preemptive tasks (which disallow any preemption) when the system does not know the future job release patterns of the tasks. In this paper, we develop a scheduling algorithm for a real-time system with a symmetry multiprocessor platform, which requires only limited information about the future job release patterns of a set of non-preemptive tasks, called LCEDF. We then derive its schedulability analysis that provides timing guarantees of the non-preemptive task set on a symmetry multiprocessor platform. Via simulations, we demonstrate the proposed schedulability analysis for LCEDF significantly improves the schedulability performance in meeting timing constraints of a set of non-preemptive tasks up to 20.16%, compared to vanilla non-preemptive EDF.

A Review of Hierarchical Fixed Priority Scheduling

2014 ◽  
Vol 536-537 ◽  
pp. 566-569
Author(s):  
Feng Xiang Zhang
Keyword(s):  
Real Time ◽  
Schedulability Analysis ◽  
Priority Scheduling ◽  
Scheduling Policies ◽  
Fixed Priority ◽  
Fixed Priority Scheduling ◽  
Priority Algorithms ◽  
Priority Systems ◽  
Real Time Applications ◽  
Global And Local

This paper focus on two level hierarchical scheduling where several real-time applications are scheduled by the fixed priority algorithms. The application with its real-time tasks is bound to a server which can be modeled as a sporadic task with special care for the schedulability analysis. Different scheduling policies and servers can be applied for hierarchical fixed priority systems, this paper gives a closer review of schedulability analysis for applications and tasks when the global and local schedulers of a system are fixed priority.

scholarly journals Energy-Efficient NoC-Based Systems for Real-Time Multimedia Applications using Approximate Computing

2021 ◽  
Author(s):  
Wagner I. Penny ◽  
Daniel M. Palomino ◽  
Marcelo S. Porto ◽  
Bruno Zatt
Keyword(s):  
Real Time ◽  
Video Processing ◽  
Energy Efficient ◽  
Processing System ◽  
Schedulability Analysis ◽  
Multimedia Applications ◽  
Timing Constraints ◽  
Approximate Computing ◽  
Processing Elements ◽  
Fractional Motion Estimation

This work presents an energy-efficient NoC-based system for real-time multimedia applications employing approximate computing. The proposed video processing system, called SApp-NoC, is efficient in both energy and quality (QoS), employing a scalable NoC architecture composed of processing elements designed to accelerate the HEVC Fractional Motion Estimation (FME). Two solutions are proposed: HSApp-NoC (Heuristc-based SApp-NoC), and MLSApp-NoC (Machine Learning-based SApp-NoC). When compared to a precise solution processing 4K videos at 120 fps, HSApp-NoC and MLSApp-NoC reduce about 48.19% and 31.81% the energy consumption, at small quality reduction of 2.74% and 1.09%, respectively. Furthermore, a set of schedulability analysis is also proposed in order to guarantee the meeting of timing constraints at typical workload scenarios.

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