scholarly journals Dynamic Priority Real-Time Scheduling on Power Asymmetric Multicore Processors

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1488
Author(s):  
Basharat Mahmood ◽  
Naveed Ahmad ◽  
Majid Iqbal Khan ◽  
Adnan Akhunzada
Keyword(s):  
Real Time ◽  
Power Efficiency ◽  
Multicore Processors ◽  
Real Time Systems ◽  
Real Time Scheduling ◽  
Dynamic Priority ◽  
Time Scheduling ◽  
Asymmetric Multicore Processors ◽  
Asymmetric Multicore ◽  
Time Systems

The use of real-time systems is growing at an increasing rate. This raises the power efficiency as the main challenge for system designers. Power asymmetric multicore processors provide a power-efficient platform for building complex real-time systems. The utilization of this efficient platform can be further enhanced by adopting proficient scheduling policies. Unfortunately, the research on real-time scheduling of power asymmetric multicore processors is in its infancy. In this research, we have addressed this problem and added new results. We have proposed a dynamic-priority semi-partitioned algorithm named: Earliest-Deadline First with C=D Task Splitting (EDFwC=D-TS) for scheduling real-time applications on power asymmetric multicore processors. EDFwC=D-TS outclasses its counterparts in terms of system utilization. The simulation results show that EDFwC=D-TS schedules up to 67% more tasks with heavy workloads. Furthermore, it improves the processor utilization up to 11% and on average uses 14% less cores to schedule the given workload.

scholarly journals Task-Level Re-Execution Framework for Improving Fault Tolerance on Symmetry Multiprocessors

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 651 ◽  
Author(s):  
Hyeongboo Baek ◽  
Jaewoo Lee
Keyword(s):  
Real Time ◽  
Fault Tolerant ◽  
Target System ◽  
Real Time Systems ◽  
Software Faults ◽  
Real Time Scheduling ◽  
Time Scheduling ◽  
Hard Real Time ◽  
Deployed Systems ◽  
Time Systems

Hard real-time systems are employed in military, aeronautics, and astronautics fields where deployed systems are susceptible to software faults that can result in functional errors. Thus, there is a need to use fault-tolerant (FT) real-time scheduling. Among the various fault-tolerant real-time scheduling techniques, re-execution has been applied widely to existing real-time systems owing to its simplicity and applicability. However, re-execution requires multiple executions of every task, and some tasks miss their deadlines owing to the prolonged execution time; therefore, it has been found to be suitable for only soft real-time systems. In this paper, we propose an FT policy that can be incorporated into most (if not all) existing real-time scheduling algorithms on multiprocessor systems, which improves the reliability of the target system without a tradeoff against schedulability. As a case study, we apply the FT policy to existing fixed-priority scheduling and earliest deadline zero-laxity scheduling, and we demonstrate that it enhances reliability without schedulability loss.

New Hybrid Genetic Based Approach for Real-Time Scheduling of Reconfigurable Embedded Systems

2018 ◽  
Vol 10 (1) ◽  
pp. 23-36
Author(s):  
Ibrahim Gharbi ◽  
Hamza Gharsellaoui ◽  
Sadok Bouamama
Keyword(s):  
Embedded System ◽  
Real Time ◽  
Scheduling Algorithm ◽  
Journal Article ◽  
Real Time Systems ◽  
Software Faults ◽  
Real Time Scheduling ◽  
Time Scheduling ◽  
Algorithmic Approaches ◽  
Time Systems

This journal article deals with the problem of real-time scheduling of operating systems (OS) tasks by a hybrid genetic-based scheduling algorithm. Indeed, most of real-time systems are framed with aid of priority-based scheduling algorithms. Nevertheless, when such a scenario is applied to save the system at the occurrence of hardware-software faults, or to improve its performance, some real-time properties can be violated at run-time. In contrast, most of the applications of real-time systems are based on timing constraints, i.e. OS tasks should be scheduled properly to finish their execution within the time specified by the real-time systems. For this reason, the authors propose in their article, a hybrid genetic-based scheduling approach that automatically checks the systems feasibility after any reconfiguration scenario was applied to an embedded system. A benchmark example is given, and the experimental results demonstrate the effectiveness of the originally proposed genetic-based scheduling approach over other such classical genetic algorithmic approaches.

On the Competitiveness of Online Real-Time Scheduling with Rate of Progress Guarantees

2003 ◽  
Vol 14 (03) ◽  
pp. 359-370 ◽  
Author(s):  
Michael A. Palis
Keyword(s):  
Real Time ◽  
Task Scheduling ◽  
Competitive Ratio ◽  
Scheduling Algorithm ◽  
Real Time Systems ◽  
Real Time Scheduling ◽  
Qos Guarantees ◽  
Time Scheduling ◽  
Time Systems

This paper investigates the task scheduling problem in the oontext of reservation-based real-time systems that provide quality of service (QoS) guarantees. In such a system, each incoming task specifies a rate of progress requirement on the task's execution that must be met by the system in order for the computation to be deeemed usable. A new metric, called granularity, is introduced that quantifies both the maximum slowdown and the variance in execution rate that the task allows. This metric generalizes the stretch metric used in recent research on task scheduling. An online preemptive scheduling algorithm is presented that achieves a competitive ratio of g(1 - r) for every set of tasks with maximum rate r and minimum granularity g. This result generalizes a previous result based on the stretch metric that showed that a competitive ratio of (1 - r) is achievable for the case when g = 1.

Reconfiguration of Synchronous Real-Time Operating System

2013 ◽  
Vol 2 (1) ◽  
pp. 114-132 ◽  
Author(s):  
Hamza Gharsellaoui ◽  
Mohamed Khalgui ◽  
Samir Ben Ahmed
Keyword(s):  
Real Time ◽  
Systems Engineering ◽  
Scheduling Algorithm ◽  
User Requirements ◽  
Real Time Systems ◽  
Real Time Scheduling ◽  
Temporal Properties ◽  
Time Scheduling ◽  
Run Time ◽  
Time Systems

Real-time scheduling is the theoretical basis of real-time systems engineering. Earliest Deadline first (EDF) is an optimal scheduling algorithm for uniprocessor real-time systems. The paper deals with Reconfigurable Uniprocessor embedded Real-Time Systems classically implemented by different OS tasks that the authors suppose independent, synchronous and periodic to meet functional and temporal properties described in user requirements. They define two forms of automatic reconfigurations which are applied at run-time: Addition-Remove of tasks or just modifications of their temporal parameters: WCET and/or Periods. The authors define a new semantic of the reconfiguration where a crucial criterion to consider is the automatic improvement of the system’s feasibility at run-time by using an Intelligent Agent that automatically checks the system’s feasibility after any reconfiguration scenario to verify if all tasks meet the required deadlines. To handle all possible reconfiguration solutions, the authors propose an agent-based architecture that applies automatic reconfigurations to re-obtain the system’s feasibility and satisfy user requirements. Therefore, they developed the tool RT-Reconfiguration to support these contributions that they apply on the running example system and the authors apply the Real-Time Simulator, Cheddar to check the whole system behavior and evaluate the performance of the algorithm. They present simulations of this architecture where the agent that implemented is evaluated.

Performance Analysis of Preemptive Based Uniprocessor Scheduling

2016 ◽  
Vol 6 (4) ◽  
pp. 1489 ◽  
Author(s):  
M Shanmugasundaram ◽  
R Kumar ◽  
Harish M Kittur
Keyword(s):  
Performance Analysis ◽  
Response Time ◽  
Real Time ◽  
Time Constraints ◽  
Real Time Systems ◽  
Real Time Scheduling ◽  
Analysis Methodology ◽  
Time Scheduling ◽  
Time Systems ◽  
Uniprocessor Scheduling

All the real-time systems are bound with response time constraints, or else, there is a risk of  severe consequences, which includes failure. The System will fail when not able to meet the requirements according to the specifications. The problem of real-time scheduling is very vast, ranging from uni-processor to complicated-multiprocessor. In this paper, we have compared the performance of real-time tasks that should be scheduled properly, to get optimum performance. Analysis methodology and the concept of optimization leads to the design of appropriate scheduling. We have done  the analysis among RM and EDF algorithm that are important for scheduling in uni-processor.

New Hybrid Genetic Based Approach for Real-Time Scheduling of Reconfigurable Embedded Systems

2021 ◽  
pp. 1140-1155
Author(s):  
Ibrahim Gharbi ◽  
Hamza Gharsellaoui ◽  
Sadok Bouamama
Keyword(s):  
Embedded System ◽  
Real Time ◽  
Scheduling Algorithm ◽  
Journal Article ◽  
Real Time Systems ◽  
Software Faults ◽  
Real Time Scheduling ◽  
Time Scheduling ◽  
Algorithmic Approaches ◽  
Time Systems

This journal article deals with the problem of real-time scheduling of operating systems (OS) tasks by a hybrid genetic-based scheduling algorithm. Indeed, most of real-time systems are framed with aid of priority-based scheduling algorithms. Nevertheless, when such a scenario is applied to save the system at the occurrence of hardware-software faults, or to improve its performance, some real-time properties can be violated at run-time. In contrast, most of the applications of real-time systems are based on timing constraints, i.e. OS tasks should be scheduled properly to finish their execution within the time specified by the real-time systems. For this reason, the authors propose in their article, a hybrid genetic-based scheduling approach that automatically checks the systems feasibility after any reconfiguration scenario was applied to an embedded system. A benchmark example is given, and the experimental results demonstrate the effectiveness of the originally proposed genetic-based scheduling approach over other such classical genetic algorithmic approaches.

scholarly journals Beyond the limitations of real-time scheduling theory: a unified scheduling theory for the analysis of real-time systems

2021 ◽  
Author(s):  
Frank Slomka ◽  
Mohammadreza Sadeghi
Keyword(s):  
Response Time ◽  
Real Time ◽  
Scheduling Theory ◽  
Real Time Systems ◽  
Response Time Analysis ◽  
Time Analysis ◽  
Worst Case ◽  
Real Time Scheduling ◽  
Time Scheduling ◽  
Time Systems

AbstractWe investigate the mathematical properties of event bound functions as they are used in the worst-case response time analysis and utilization tests. We figure out the differences and similarities between the two approaches. Based on this analysis, we derive a more general form do describe events and event bounds. This new unified approach gives clear new insights in the investigation of real-time systems, simplifies the models and will support algebraic proofs in future work. In the end, we present a unified analysis which allows the algebraic definition of any scheduler. Introducing such functions to the real-time scheduling theory will lead two a more systematic way to integrate new concepts and applications to the theory. Last but not least, we show how the response time analysis in dynamic scheduling can be improved.

scholarly journals PERTS: A PROTOTYPING ENVIRONMENT FOR REAL-TIME SYSTEMS

1996 ◽  
Vol 06 (02) ◽  
pp. 161-177 ◽  
Author(s):  
J.W.S. LIU ◽  
C.L. LIU ◽  
Z. DENG ◽  
T.S. TIA ◽  
J. SUN ◽  
...  
Keyword(s):  
Real Time ◽  
Management Strategies ◽  
Real Time Systems ◽  
Resource Assignment ◽  
Real Time System ◽  
Real Time Scheduling ◽  
Simulation Tools ◽  
Software Modules ◽  
Time Scheduling ◽  
Time Systems

This paper describes PERTS, a prototyping environment for real-time systems. PERTS provides a comprehensive set of design, validation, and simulation tools that are built on recent theoretical advances. It also provides software modules that implement wellknown and novel real-time scheduling algorithms, task and resource assignment algorithms, and resource access control protocols. Together, the tools and software modules support the systematic and rigorous evaluation of new designs, experimentation with alternative scheduling and resource management strategies, and the evaluation and validation of the resultant real-time system.

scholarly journals Performance Analysis of Preemptive Based Uniprocessor Scheduling

2016 ◽  
Vol 6 (4) ◽  
pp. 1489
Author(s):  
M Shanmugasundaram ◽  
R Kumar ◽  
Harish M Kittur
Keyword(s):  
Performance Analysis ◽  
Response Time ◽  
Real Time ◽  
Time Constraints ◽  
Real Time Systems ◽  
Real Time Scheduling ◽  
Analysis Methodology ◽  
Time Scheduling ◽  
Time Systems ◽  
Uniprocessor Scheduling

All the real-time systems are bound with response time constraints, or else, there is a risk of  severe consequences, which includes failure. The System will fail when not able to meet the requirements according to the specifications. The problem of real-time scheduling is very vast, ranging from uni-processor to complicated-multiprocessor. In this paper, we have compared the performance of real-time tasks that should be scheduled properly, to get optimum performance. Analysis methodology and the concept of optimization leads to the design of appropriate scheduling. We have done  the analysis among RM and EDF algorithm that are important for scheduling in uni-processor.

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