An Adaptive Scheme for Fault-Tolerant Scheduling of Soft Real-Time Tasks in Multiprocessor Systems

Al-Omari, R.; Somani, Arun K.; Manimaran, G.

doi:10.1007/3-540-45307-5_7

Cited by 16 publications

(33 citation statements)

References 7 publications

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“…Nevertheless, our approach can be applied to dependent tasks because tasks having precedence constraints are equivalent to independent tasks by modifying ready times and deadlines of dependent tasks [18]. Moreover, fault-tolerant scheduling algorithms can be classified into two groups: preemptive scheduling [27], [28] and nonpreemptive scheduling [25], [26], [32], [33]. In a preemptive scheduling approach, an executing task can be preempted by another task.…”

Section: Related Workmentioning

confidence: 99%

“…Although preemptive scheduling is able to achieve high system utilization, in many real-world cases, hardware devices and software configuration make preemptions either impossible or prohibitively expensive. Nonpreemptive scheduling, on the other hand, has the advantages of accurate response time analysis, ease of implementation, no synchronization overhead, and reduced stack memory requirements [19], [20], [33]. Nonpreemptive scheduling has proven to be beneficial in many applications, such as multimedia applications [21].…”

Section: Related Workmentioning

confidence: 99%

“…Yang et al studied a fault-tolerant scheduling algorithm where the two copies of a task were executed simultaneously in order to improve schedulability [32]. Al-Omari et al investigated an adaptive scheme that controlled the overlap interval between the primary copy and backup copy of a task based on the primary-fault probability and the task's laxity [33]. Although these methods overcome the drawbacks of the passive backupcopy scheme, the existing scheduling solutions are still inadequate for a heterogeneous computing environment.…”

Section: Related Workmentioning

confidence: 99%

See 2 more Smart Citations

QoS-Aware Fault-Tolerant Scheduling for Real-Time Tasks on Heterogeneous Clusters

Zhu

Qin

Qiu

2011

IEEE Trans. Comput.

109

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Abstract-Fault-tolerant scheduling plays a significant role in improving system reliability of clusters. Although extensive fault-tolerant scheduling algorithms have been proposed for real-time tasks in parallel and distributed systems, quality of service (QoS) requirements of tasks have not been taken into account. This paper presents a fault-tolerant scheduling algorithm called QAFT that can tolerate one node's permanent failures at one time instant for real-time tasks with QoS needs on heterogeneous clusters. In order to improve system flexibility, reliability, schedulability, and resource utilization, QAFT strives to either advance the start time of primary copies and delay the start time of backup copies in order to help backup copies adopt the passive execution scheme, or to decrease the simultaneous execution time of the primary and backup copies of a task as much as possible to improve resource utilization. QAFT is capable of adaptively adjusting the QoS levels of tasks and the execution schemes of backup copies to attain high system flexibility. Furthermore, we employ the overlapping technology of backup copies. The latest start time of backup copies and their constraints are analyzed and discussed. We conduct extensive experiments to compare our QAFT with two existing schemes-NOQAFT and DYFARS. Experimental results show that QAFT significantly improves the scheduling quality of NOQAFT and DYFARS.

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Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

See 1 more Smart Citation

QoS-Aware Fault-Tolerant Scheduling for Real-Time Tasks on Heterogeneous Clusters

Zhu

Qin

Qiu

2011

IEEE Trans. Comput.

109

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“…The acceptance test is a widely adopted approach to checking the correctness of schedules [17]- [19], [21], [22]. Three variants of the primary-backup approach include: 1) the active-backup-copy-based schemes [23], [24]; 2) the passive-backup-copy-based schemes [17]- [19], [21], [22]; and 3) the primary-backup-copy overloading techniques [25], [26].…”

Section: Related Workmentioning

confidence: 99%

“…An acceptance test is employed to check the correctness of schedules [17]- [19], [21], [22]. There are three variants of the primary-backup scheme: 1) the active-backup copy [23], [24]; 2) passive-backup copy [17]- [19], [21], [22]; and 3) primary-backup copy overlapping techniques [25], [26]. In the active-backup copy schemes, if a primary copy (or a backup copy) finishes before its corresponding backup copy (or primary copy), the backup copy (or the primary copy) will not be terminated and deallocated, thereby leading to wasted processor time.…”

mentioning

confidence: 99%

Exploiting Redundancies to Enhance Schedulability in Fault-Tolerant and Real-Time Distributed Systems

Luo

Qin

Tan

et al. 2009

IEEE Trans. Syst., Man, Cybern. A

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Abstract-In the past decades, distributed systems have been widely applied to real-time applications, most of which have fault-tolerance requirements to assure high reliability. Due to the stringent space constraints of real-time systems, the issue of schedulability becomes a major concern in the design of faulttolerant and real-time distributed systems. Most existing real-time and fault-tolerant scheduling algorithms, which are based on the primary-backup scheme for periodic real-time tasks, introduce unnecessary redundancies by aggressively using active-backup copies. To solve this problem, we propose two novel fault-tolerant techniques, which are seamlessly integrated with fixed-prioritybased scheduling algorithms. These techniques leverage redundancies to enhance schedulability in fault-tolerant and real-time distributed systems. Our fault-tolerant techniques make use of the primary-backup scheme to tolerate permanent hardware failures. The first technique (referred to as Tercos) terminates the execution of active-backup copies, when corresponding primary copies are successfully completed. Tercos is designed to reduce scheduling lengths in fault-free scenarios to enhance schedulability by virtue of executing portions of active-backup copies in passive forms. The second technique (referred to as Debus) uses a deferred-active-backup scheme to further minimize schedule lengths to improve the schedulability performance. Debus schedules active-backup copies as late as possible, while terminating active-backup copies when their primary copies are completed. Experimental results show that, compared with existing algorithms in literature, Tercos can significantly improve schedulability by up to 17.0% (with an average of 9.7%). Furthermore, empirical results reveal that Debus can enhance schedulability over Tercos by up to 12% (with an average of 7.8%).

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The Process of Synchronization in Dual Redundant Fault-Tolerant System

Liu

Zhang

IFIP International Federation for Information Processing

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Synchronization is used in dual redundant fault-tolerant system to make two computers work jointly. It determines the work mode and controls the operations of the system. The paper presents a dual redundant fault-tolerant system and proposes its process of synchronization based on task. The synchronization treats task as the minimal operation unit, And it is implemented with the assist of dual-computer-controller and outer memory, the latter includes task buffer and global data region. Dual-computer-controller controls the input and output of tasks that are stored in task buffer. The switch in of backup computer is implemented by duplicating global data from global data region used by host computer. Additional resolutions for key points, such as the switch between two computers, are also put forward in conclusion. It is proved that the task-level synchronization can make two computers work in phase, and the system is applicable to critical fields requiring high dependability.

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An Adaptive Scheme for Fault-Tolerant Scheduling of Soft Real-Time Tasks in Multiprocessor Systems

Cited by 16 publications

References 7 publications

QoS-Aware Fault-Tolerant Scheduling for Real-Time Tasks on Heterogeneous Clusters

QoS-Aware Fault-Tolerant Scheduling for Real-Time Tasks on Heterogeneous Clusters

Exploiting Redundancies to Enhance Schedulability in Fault-Tolerant and Real-Time Distributed Systems

The Process of Synchronization in Dual Redundant Fault-Tolerant System

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