The Task Completion Time in Degradable Systems

This paper assumes a user-oriented point of view in examining the performability of a dependable omputing system. The investigated performability measure is the e e tive time that a task, with an assigned work requirement, takes to be exe uted by the system. Assuming that the system hanges its performan e hara teristi s randomly in time, the sto hasti model representing the task ompletion time is formulated and analysed. Appli ations and extensions of the basi model are dis ussed. Finally, the ompletion time model is reformulated in the language of sto hasti Petri nets, and possible omputational approa hes are exampli ed.