Analysis of the preemptive resume policy with nonzero overhead

The authors present a basic approach to modeling a system under a preemptive resume arbitration policy with nonzero overhead (i.e., a nonwork-conserving system). They also present models for two possible overhead acquisition scenarios. The analysis is based on the concept of corrected service times. The first and second moments of service time for each priority group are adjusted to include the total accrued overhead time. Formulas for these corrected moments. as well as for the corresponding mean response times. are presented. The systems considered are n-class with noninterruptible overhead periods. The authors have defined the first and second moments of the corrected service times for each priority group in a system with arbitrarily distributed overhead and nonoverhead service times. They have also defined the corresponding mean waiting times when the nonoverhead portions of the service times are exponentially distributed. The resultant predictions have proven to be extremely accurate. even at very high utilizations