Impact of Release Jitter

Impact of the variations on the tasks’ activation instants.

• Tasks may suffer deviations on the respective activation instants, e.g. when a task is activated by the completion of another one, by an external interrupt or by the reception of a message on a communication port. In such cases the real time lapse between consecutive activations may vary with respect to the predicted values – release jitter.

• The existence of release jitter must be taken into account in the schedulability analysis, as in such cases the tasks can execute during time instants different from the assumed ones.

Schedulability tests including the impact of Relese Jitter:

• The presence of release jitter can be modeled by the anticipation of the activation instants of the following task instances.

Computing Rwc i with release jitter (J k ) for preemptive systems with fixed priorities:

Solved iteratively, as usual: