Reinder J. Bril, TU/e Informatica, System Architecture and Networking 1 Construction of time lines for FPPS Reinder J. Bril Real-Time Architectures 2003/

Reinder J. Bril, TU/e Informatica, System Architecture and Networking 2 Worst-case response times Simultaneous release of  i with all higher priority tasks at time a (critical instant). –Draw a time line with releases of the highest priority task  1 with a first release at time a. For every release, task  1 can start immediately upon every release and execute its worst-case computation time to completion. –Given the responses of tasks  1 till  i–1, draw releases of task  i with a first release at time a. For each release, the execution of task  i fills the “gaps” left by the higher priority tasks till  i has executed its worst-case computation time. The procedure is stopped when either the response time of task  j with j < i exceeds its deadline D j, in which case the set of tasks is not schedulable, or when  i completes. In the latter case, the worst-case response time WR i is found.

Reinder J. Bril, TU/e Informatica, System Architecture and Networking 3 Best-case response times Simultaneous release of all higher priority tasks with a completion of  i at time f (optimal instant). –Draw a time line with releases of the highest priority task  1 with a last release at time f – T 1. For every release, task  1 can start immediately upon every release and execute its best-case computation time to completion. –Given the responses of tasks  1 till  i–2, draw releases of task  i–1 with a last release at time f – T i–1. For each release, the execution of task  i–1 fills the “gaps” left by the higher priority tasks till  i–1 has executed its best-case computation time. –The execution of task  i fills the “gaps” left by the higher priority tasks from time f backwards in time till  i has executed its best-case computation time. The procedure is stopped when  i completes, in which case the best- case response time BR i is found.