Patent ID: 7913256

Claim:
A schedulability determination method in a real-time system including a plurality of processors for executing jobs of a plurality of periodic tasks each having a predetermined period, comprising: preparing scheduling means for assigning the processors each job in a period of each of the tasks; calculating a distribution of execution times during which jobs assigned by the scheduling means are executed on the processors; determining, based on the distribution, whether each of the jobs finishes by a deadline; determining that scheduling is impossible when one of the jobs is determined not to finish by the deadline; determining whether the distribution converges based on unexecuted jobs of the tasks whose periods have started at a first time point and a second time point that have a time difference corresponding to a least common multiple of the periods of the tasks, the distribution being of the execution times of the jobs each determined to finish by the deadline; and determining that scheduling is possible when the distribution converges, the distribution converging when the unexecuted jobs at the first time point and those at the second time point are identical to each other, wherein determining whether the distribution converges includes determining that the distribution converges when a distribution during one of two successive time intervals and a distribution during another one of two successive time intervals are identical to each other, each of the two successive time intervals corresponding to a least common multiple of the periods of the tasks after the latest release time among release times of the tasks.