Preemptive schedulers have been widely adopted in single processor real-time systems to avoid the blocking associated with the non-preemptive execution of lower priority tasks and achieve a high processor utilization. However, under fixed priority assignments, there are cases in which limiting preemptions can improve schedulability with respect to a fully preemptive solution. This is true even neglecting preemption overhead, as it will be shown in the paper. In previous works, limited-preemption schedulers have been mainly considered to reduce the preemption overhead, and make the estimation of worst-case execution times more predictable. In this work, we instead show how to improve the feasibility of fixed-priority task systems by executing the last portion of each task in a non-preemptive fashion. A proper dimensioning of such a region of code allows increasing the number of task sets that are schedulable with a fixed priority algorithm. Simulation experiments are also presented to validate the effectiveness of the proposed approach.
Improving Feasibility of Fixed Priority Tasks using Non-Preemptive Regions / Bertogna, Marko; G., Buttazzo; G., Yao. - STAMPA. - 0:(2011), pp. 251-260. (Intervento presentato al convegno IEEE Real-Time Systems Symposium (RTSS 2011) tenutosi a Vienna, Austria nel Nov. 30 - Dec. 2, 2011) [10.1109/RTSS.2011.30].
Improving Feasibility of Fixed Priority Tasks using Non-Preemptive Regions
BERTOGNA, Marko;
2011
Abstract
Preemptive schedulers have been widely adopted in single processor real-time systems to avoid the blocking associated with the non-preemptive execution of lower priority tasks and achieve a high processor utilization. However, under fixed priority assignments, there are cases in which limiting preemptions can improve schedulability with respect to a fully preemptive solution. This is true even neglecting preemption overhead, as it will be shown in the paper. In previous works, limited-preemption schedulers have been mainly considered to reduce the preemption overhead, and make the estimation of worst-case execution times more predictable. In this work, we instead show how to improve the feasibility of fixed-priority task systems by executing the last portion of each task in a non-preemptive fashion. A proper dimensioning of such a region of code allows increasing the number of task sets that are schedulable with a fixed priority algorithm. Simulation experiments are also presented to validate the effectiveness of the proposed approach.File | Dimensione | Formato | |
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