Preemption-light multiprocessor scheduling of sporadic tasks with high utilisation bound


Known algorithms capable of scheduling implicit-deadline sporadic tasks over identical processors at up to 100% utilisation invariably involve numerous preemptions and migrations. To the challenge of devising a scheduling scheme with as few preemptions and migrations as possible, for a given guaranteed utilisation bound, we respond with the algorithm NPS-F. It is configurable with a parameter, trading off guaranteed schedulable utilisation (up to 100%) vs preemptions. For any possible configuration, NPS-F introduces fewer preemptions than any other known algorithm matching its utilisation bound. A clustered variant of the algorithm, for systems made of multicore chips, eliminates (costly) off-chip task migrations, by dividing processors into disjoint clusters, formed by cores on the same chip (with the cluster size being a parameter). Clusters are independently scheduled (each, using non-clustered NPS-F). The utilisation bound is only moderately affected. We also formulate an important extension (applicable to both clustered and non-clustered NPS-F) which optimises the supply of processing time to executing tasks and makes it more granular. This reduces processing capacity requirements for schedulability without increasing preemptions.

DOI: 10.1007/s11241-011-9114-0

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@article{Bletsas2009PreemptionlightMS, title={Preemption-light multiprocessor scheduling of sporadic tasks with high utilisation bound}, author={Konstantinos Bletsas and Bj{\"{o}rn Andersson}, journal={Real-Time Systems}, year={2009}, volume={47}, pages={319-355} }