Abstract:The best and worst response times on which jitter analysis was relied were calculated. An assumption was made that a task' s deadline had to be smaller than or equal to its period when the best response time was calculated. The exact analysis derived with level-i busy period could be used to compute the best-case response times of periodic tasks under fixed-priority preemptive scheduling and arbitrary phasing with deadlines longer than the periods. The exact analysis proved that there was an optimal completion instant for an execution of the task. By constructing the expansion job in the level-i busy period, the algorithm of computing best-case response time of tasks with deadline greater than its period was obtained by the analysis of the optimal completion instant of the expansion job. The correctness of the algorithm was proved.