PIPELINED PROCESSORS AND WORST-CASE EXECUTION TIMES

The calculation of worst case execution time (WCET) is a fundamental r equirement of almost all scheduling approaches for hard real-time syst ems. Due to their unpredictability, hardware enhancements such as cach e and pipelining are often ignored in attempts to find WCET of program s. This results in estimations that are excessively pessimistic. In th is article a simple instruction pipeline is modeled so that more accur ate estimations are obtained. The model presented can be used with any schedulability analysis that allows sections of nonpreemptable code t o be included. Our results indicate the WCET overestimates at basic bl ock level can be reduced from over 20% to less than 2%, and that the o verestimates for typical structured real-time programs can be reduced by 17%-40%.