The task Propose values for time budget
segments fills in the values of the time budget segments identified previously. This has to be done considering the
acquired time budget influencing properties, in particular the response times. In general, it is desirable to add a
slight margin to the budget segment compared to the estimated and analyzed response times in order to provide for more
relaxed implementation. However, it could even be the case that the resulting time budget for a certain component is
smaller than a WCET property over the same component that was transformed from a lower abstraction level. In such
cases, the lower-level solution needs to be reworked to comply with the (new) time budget.
When making a time budget, not only the current solution (regardless of abstraction level) needs to be
considered, but also the influence of future functionality. Future functionality refers to both functionality that is
planned but not yet implemented, and to still unknown functionality that potentially is to be included in future
generations of the system. The task Propose values for time budget segments
therefore also needs to compare the solution and its time budget properties with the product plan to identify which
functionality is still to be added to the system, and also make an assessment of the influence of unknown
functionality. Based on this information, the developer needs to assess how much the still missing functionality
affects the end-to-end event chain currently under investigation. This will eventually lead to introducing slack in the
final time budget. Typical properties that are affected are communication delay (increased congestion) and task
execution periods (increased competition for computation power), which both lead to a longer end-to-end delay.
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