FPSL, FPCL and FPZL schedulability analysis

Davis, Robert I.; Kato, Shigeo

doi:10.1007/s11241-012-9149-x

Cited by 13 publications

(4 citation statements)

References 36 publications

(73 reference statements)

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“…ZL policy can improve the performance of fixed priority scheduling algorithms dramatically. ZL policy has been analyzed and adapted to many real-time scheduling schemes [12,[32][33][34][35][36]. EDZL [7] is a global scheduling algorithm for multiprocessor real-time systems that firstly employs ZL policy.…”

Section: Real-time Scheduling On Multiprocessorsmentioning

confidence: 99%

A Comparative Study on the Schedulability of the EDZL Scheduling Algorithm on Multiprocessors

Han,

Paik,

et al. 2023

Applied Sciences

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As multiprocessor (or multicore) real-time systems become popular, there has been much research on multiprocessor real-time scheduling algorithms. This work evaluates EDZL (Earliest Deadline until Zero Laxity), a scheduling algorithm for real-time multiprocessor systems. First, we compare the performance of EDZL schedulability tests. We measure and compare the ratio of task sets admitted by each test. We also investigate the dominance between EDZL schedulability tests and discover that the union of the demand-based test and the utilization-based test is an effective combination. Second, we compare the schedulability of EDZL and EDF(k). We prove that the union of the EDZL schedulability tests dominates the EDF(k) schedulability test, i.e., the union of the EDZL schedulability tests can admit all task sets admitted by the EDF(k) schedulability test. We also compare the schedulability of EDZL and EDF(k) through scheduling simulation by measuring the ratio of successfully scheduled task sets. EDZL can successfully schedule 7.0% more task sets than EDF(k).

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Section: Real-time Scheduling On Multiprocessorsmentioning

confidence: 99%

A Comparative Study on the Schedulability of the EDZL Scheduling Algorithm on Multiprocessors

Han,

Paik,

et al. 2023

Applied Sciences

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“…gFPDS is broadly similar to the dynamic algorithm FPZL [24], [25]. FPZL resembles gFPPS until a job reaches a state of zero laxity i.e.…”

Section: B Global Fixed Priority Schedulingmentioning

confidence: 99%

“…In the case of gFPDS, we used the FNR algorithm to obtain optimum final non-pre-emptive region lengths in conjunction with the heuristic priority assignment policies, and the FNR-PA Algorithm to provide both priority and FNR length assignment. We also made comparisons with the dynamic scheduling algorithm FPZL [24], [25] which has some similarities in its behaviour to gFPDS. The lines on the graphs are labelled according to the scheduling algorithm and priority assignment policy used, e.g.…”

Section: Experimental Evaluationmentioning

confidence: 99%

Global fixed priority scheduling with deferred pre-emption

Davis

Burns

Marinho

et al. 2013

2013 IEEE 19th International Conference on Embedded and Real-Time Computing Systems and Applications

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Abstract-This paper introduces schedulability analysis for global fixed priority scheduling with deferred pre-emption (gFPDS) for homogeneous multiprocessor systems. gFPDS is a superset of global fixed priority pre-emptive scheduling (gFPPS) and global fixed priority non-pre-emptive scheduling (gFPNS). We show how schedulability can be improved via appropriate choice of priority assignment and final non-pre-emptive region lengths, and we provide algorithms which optimize schedulability in this way. An experimental evaluation shows that gFPDS significantly outperforms both gFPPS and gFPNS. I.INTRODUCTION A common misconception with regard to fixed priority scheduling of sporadic tasks is that fully pre-emptive scheduling is more effective in terms of schedulability than non-pre-emptive scheduling. The two are however incomparable; there are tasksets that are schedulable under fixed priority non-pre-emptive scheduling that are not schedulable under fixed priority pre-emptive scheduling and vice-versa. This is the case for uniprocessor scheduling [27] and also the case for global multiprocessor scheduling [30], which is the focus of this paper.While the blocking effect, due to long non-pre-emptive regions of low priority tasks degrades schedulability for single processor systems that have a wide range of task execution times and periods (as illustrated by Figure 7 in [27]), Guan et al. [30] showed that the same is not necessarily true for multiprocessor systems. With m processors rather than one, long non-pre-emptive regions can be accommodated without necessarily compromising the schedulability of higher priority tasks. However, this advantage only extends so far; with m processors then m long non-pre-emptive regions are enough to significantly compromise schedulability. In this context, limited non-preemptive execution has the advantage of reducing the number of pre-emptions, and potentially improving the worst-case response time of tasks, while also keeping blocking effects on higher priority tasks within tolerable limits.In the literature, the term fixed priority scheduling with deferred pre-emption has been used to refer to a variety of different techniques by which pre-emptions may be deferred for some interval of time after a higher priority task becomes ready. These are described in a survey by Buttazzo et al. [21] and briefly discussed in Section II. In this paper, we assume a simple form of fixed priority scheduling with deferred preemption where each task has a single non-pre-emptive region at the end of its execution. If this region is of the minimum possible length for all tasks, then we have fully pre-emptive scheduling, whereas if it constitutes all of the task's execution time then we have non-pre-emptive scheduling.In this paper, we introduce sufficient schedulability tests for global fixed priority scheduling with deferred pre-

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“…De plus, les résultats expérimentaux que nous avons menés montrent également un nombre plus important de systèmes exécutés sans dépassement d'échéance(Chéramy, 2014).4.3. Algorithmes d'ordonnancement à laxité nulle (Zero Laxity)Les politiques RMZL, FPZL(Davis, Kato, 2012) et EDZL (S Lee, 1994…”

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Algorithmes pour l’ordonnancement temps réel multiprocesseur

Chéramy¹,

Hladik²,

Déplanche³

2014

Journal Européen des Systèmes Automatisés

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Cet article expose les principales politiques d'ordonnancement temps réel existantes pour des architectures multiprocesseurs et homogènes. Cette présentation a pour but de guider le lecteur à travers la très grande profusion d'articles dans ce domaine et lui fournir les principales clefs de compréhension des algorithmes. L'étude se focalise sur les approches dites globales et hybrides et en montre leur très grande variété. ABSTRACT. This article presents the main real-time scheduling policies available to homogeneous multiprocessor architectures. The objective of this study is to guide the reader through the variety of scientific publications in this domain and to give him the main keys for understanding these algorithms. The article focuses on global and hybrid approaches and shows their considerable diversity.

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FPSL, FPCL and FPZL schedulability analysis

Cited by 13 publications

References 36 publications

A Comparative Study on the Schedulability of the EDZL Scheduling Algorithm on Multiprocessors

A Comparative Study on the Schedulability of the EDZL Scheduling Algorithm on Multiprocessors

Global fixed priority scheduling with deferred pre-emption

Algorithmes pour l’ordonnancement temps réel multiprocesseur

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