Reducing Preemptions and Migrations in Real-Time Multiprocessor Scheduling Algorithms by Releasing the Fairness

Nelissen, Geoffrey; Berten, Vandy; Goossens, Joël; Milojevic, Dragomir

doi:10.1109/rtcsa.2011.57

Cited by 17 publications

(23 citation statements)

References 20 publications

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“…That is, PFair algorithms cause much more overheads than Boundary Fair (or DPFair) approaches which in turn are more costly in terms of preemptions than EKG. Finally, it was shown that RUN and U-EDF dominate all these algorithms [1], [15].…”

Section: Related Workmentioning

confidence: 99%

“…Finally, a previous version of the U-EDF algorithm was presented in [1] showing a drastic improvement of the number of preemptions and migrations due to the fairness release. An interesting observation issued from the study of all the aforementioned algorithms, is the fact that the number of preemptions and migrations decreases as the fairness constraint is relaxed.…”

Section: Related Workmentioning

confidence: 99%

“…Furthermore, the reader probably noticed that, on Figure 1(d), τ 3 instantly migrates from π 2 to π 1 at time 5, and inversely at time 7. A virtual processor mechanism presented in [1] avoids these pointless migrations and produces the schedule illustrated in Figure 1(e).…”

Section: B Scheduling Tasksmentioning

confidence: 99%

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mentioning

confidence: 99%

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U-EDF: An Unfair But Optimal Multiprocessor Scheduling Algorithm for Sporadic Tasks

Nelissen

Berten

Nélis

et al. 2012

2012 24th Euromicro Conference on Real-Time Systems

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Abstract-A multiprocessor scheduling algorithm named U-EDF, was presented in [1] for the scheduling of periodic tasks with implicit deadlines. It was claimed that U-EDF is optimal for periodic tasks (i.e., it can meet all deadlines of every schedulable task set) and extensive simulations showed a drastic improvement in the number of task preemptions and migrations in comparison to state-of-the-art optimal algorithms. However, there was no proof of its optimality and U-EDF was not designed to schedule sporadic tasks.In this work, we propose a generalization of U-EDF for the scheduling of sporadic tasks with implicit deadlines, and we prove its optimality. Contrarily to all other existing optimal multiprocessor scheduling algorithms for sporadic tasks, U-EDF is not based on the fairness property. Instead, it extends the main principles of EDF so that it achieves optimality while benefiting from a substantial reduction in the number of preemptions and migrations.

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Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

Section: B Scheduling Tasksmentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

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U-EDF: An Unfair But Optimal Multiprocessor Scheduling Algorithm for Sporadic Tasks

Nelissen

Berten

Nélis

et al. 2012

2012 24th Euromicro Conference on Real-Time Systems

Self Cite

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“…The scheduling algorithm decides which processor the task will be executed on, as well as the order of the tasks' execution. Although a scheduling algorithm may be optimal, sometimes it cannot be applied practically [9]. This is because of the scheduling overheads, in terms of task preemptions and migrations that accompany its work.…”

Section: Introductionmentioning

confidence: 99%

Minimizing scheduling overhead in LRE-TL real-time multiprocessor scheduling algorithm

Alhussian¹,

Zakaria²,

Hussin³

2017

Turk J Elec Eng & Comp Sci

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Abstract:In this paper, we present a modification of the local remaining execution-time and local time domain (LRE-TL) real-time multiprocessor scheduling algorithm, aimed at reducing the scheduling overhead in terms of task migrations.LRE-TL achieves optimality by employing the fairness rule at the end of each time slice in a fluid schedule model. LRE-TL makes scheduling decisions using two scheduling events. The bottom (B) event, which occurs when a task consumes its local utilization, has to be preempted in order to resume the execution of another task, if any, or to idle the processor if none exist. The critical (C) event occurs when a task consumes its local laxity, which means that the task cannot wait anymore and has to be scheduled for execution immediately or otherwise it will miss its deadline. Event C always results in a task migration. We have modified the initialization procedure of LRE-TL to make sure that tasks that have higher probability of firing a C event will always be considered for execution first. This will ensure that the number of C events will always be at a minimum, thereby reducing the number of task migrations.

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Cluster formation techniques for hierarchical real time tasks allocation on multiprocessor system

Talmale

Shrawankar

2021

Concurrency and Computation

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Summary Real‐time systems are nowadays extensively used in most time‐critical embedded applications. The existing multiprocessor real‐time scheduling algorithms are based on partitioned and global scheduling approaches. The partitioned‐based algorithms suffer poor utilization bound, load balancing, not compatible for an open system environment, and the global scheduling approach faces problems like high scheduling, migration overhead. Cluster scheduling represents a hybrid scheduling approach which consists of a set of processors as clusters and tasks scheduled to each processor of clusters using a global scheduling approach. The different cluster formation heuristics are investigated for homogenous clusters. The main objective of this article is to propose task utilization‐based cluster formation and harmonic period aware task allocation for a hierarchical real‐time system on a multiprocessor platform. Tasks with high utilization, cluster size tune to a smaller value to achieve high utilization. Tasks with low utilization, the size of cluster tune to larger to reduce migration and scheduling overheads. Experimentation performed on multiprocessor real‐time simulator with a different set of tasks, multiprocessor system, different tasks utilization, and cluster size. Simulation results show that cluster base approach increases the number of tasks scheduled on a multiprocessor system, system utilization, and reduces response time, migration, and preemption overheads.

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Reducing Preemptions and Migrations in Real-Time Multiprocessor Scheduling Algorithms by Releasing the Fairness

Cited by 17 publications

References 20 publications

U-EDF: An Unfair But Optimal Multiprocessor Scheduling Algorithm for Sporadic Tasks

U-EDF: An Unfair But Optimal Multiprocessor Scheduling Algorithm for Sporadic Tasks

Minimizing scheduling overhead in LRE-TL real-time multiprocessor scheduling algorithm

Cluster formation techniques for hierarchical real time tasks allocation on multiprocessor system

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