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.

scholarly journals An N-Modular Redundancy Framework Incorporating Response-Time Analysis on Multiprocessor Platforms

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 960 ◽  
Author(s):  
Jaemin Baek ◽  
Jeonghyun Baek ◽  
Jeeheon Yoo ◽  
Hyeongboo Baek
Keyword(s):  
Real Time ◽  
Fault Tolerant ◽  
Target System ◽  
Real Time Scheduling ◽  
Multiprocessor Platforms ◽  
Average System ◽  
Time Scheduling ◽  
Modular Redundancy ◽  
Hard Real Time ◽  
High Level

A timing constraint and a high level of reliability are the fundamental requirements for designing hard real-time systems. To support both requirements, the N modular redundancy (NMR) technique as a fault-tolerant real-time scheduling has been proposed, which executes identical copies for each task simultaneously on multiprocessor platforms, and a single correct one is voted on, if any. However, this technique can compromise the schedulability of the target system during improving reliability because it produces N identical copies of each job that execute in parallel on multiprocessor platforms, and some tasks may miss their deadlines due to the enlarged computing power required for completing their executions. In this paper, we propose task-level N modular redundancy (TL-NMR), which improves the system reliability of the target system of which tasks are scheduled by any fixed-priority (FP) scheduling without schedulability loss. Based on experimental results, we demonstrate that TL-NMR maintains the schedulability, while significantly improving average system safety compared to the existing NMR.

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.

A Fault-Tolerant Scheduling Algorithm Based on Checkpointing and Redundancy for Distributed Real-Time Systems

2019 ◽  
Vol 10 (3) ◽  
pp. 58-75 ◽  
Author(s):  
Barkahoum Kada ◽  
Hamoudi Kalla
Keyword(s):  
Real Time ◽  
Fault Tolerant ◽  
Scheduling Algorithm ◽  
Real Time Systems ◽  
Transient Faults ◽  
Spare Capacity ◽  
Tolerance Approach ◽  
Architecture Simulation ◽  
Hard Real Time ◽  
Time Systems

Real-time systems are becoming ever more widely used in life-critical applications, and the need for fault-tolerant scheduling can only grow in the years ahead. This article presents a novel fault tolerance approach for tolerating transient faults in hard real-time systems. The proposed approach combines both checkpointing with rollback and active replication to tolerate several transient faults. Based on this approach, a new static fault-tolerant scheduling algorithm SFTS is presented. It is based on a list of scheduling heuristics which satisfy the application time constraints even in the presence of faults by exploring the spare capacity of available processors in the architecture. Simulation results show the performance and effectiveness of the proposed approach compared to other fault-tolerant approaches. The results reveal that in the presence of multiple transient faults, the average timing overhead of this approach is lower than checkpointing technique. Moreover, the proposed algorithm SFTS achieves better feasibility rate in the presence of multiple transient faults.

Quasi-static fault-tolerant scheduling schemes for energy-efficient hard real-time systems

2012 ◽  
Vol 85 (6) ◽  
pp. 1386-1399 ◽  
Author(s):  
Tongquan Wei ◽  
Piyush Mishra ◽  
Kaijie Wu ◽  
Junlong Zhou
Keyword(s):  
Real Time ◽  
Energy Efficient ◽  
Fault Tolerant ◽  
Real Time Systems ◽  
Hard Real Time ◽  
Time Systems
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