Deferred preemption enables a trade-off between the high dynamics of a preemptive schedule on the one hand, and the predictability of a non-preemptive system on the other hand. In addition to bounds on the execution time and the context-switch costs, the schedulability analysis for deferred preemption needs the maximum time a preemption can be delayed, called maximum blocking time. Scheduling theory is based on an abstraction level where these values are assumed to be given. So, the related work focuses on the scheduling analysis and not on the computation of the maximum blocking time. In this paper, we propose a new method to determine the maximum blocking time of a task given a fixed set of preemption points. To derive a sound upper bound, our approach also includes the safe determination of the context-switch costs which might increase the maximum blocking time.
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