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Computación y Sistemas

Print version ISSN 1405-5546

Abstract

GUEVARA LOPEZ, Pedro; VALDEZ MARTINEZ, Jorge Salvador  and  DELGADO REYES, Gustavo. Concurrent Real-Time Task Schedulers: A Classification Based on Functions and Set Theory. Comp. y Sist. [online]. 2014, vol.18, n.4, pp.809-820. ISSN 1405-5546.  http://dx.doi.org/10.13053/CyS-18-4-1543.

Real-Time Operating Systems must provide support for concurrency; to achieve this, task schedulers are necessary. Schedulers operate on a set of concurrent real-time tasks in which its instances are to complete their execution within their respective deadlines; a scheduler receives a set of arrival times and maps it to a set of start times for the instances to begin their execution. In this context, a scheduler is considered to be a function that performs mapping between two sets which evolve in time, with respect to this we present a classification of schedulers, based on functions and set theory, into such categories as critical, non-critical, static, adaptive, predictive, preemptive, and optimal. Our proposed classification is novel because the state of the art classifications are only verbal and non-formal and they do not support elements which assist in analysis, modeling and/or characterization of schedulers. As an additional result, this classification can be used for future qualitative studies of optimality, stability, controllability, efficiency, convergence, and predictability from the computational point of view. The paper concludes with two examples of schedulers: RM (Rate Monotonic) and EDF (Earliest Deadline First).

Keywords : Arrival time; function; starting time; scheduler; classification; real-time system.

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