Influence of bus allocation algorithms on the system performance of multiprocessor systems with a time-shared bus. An experience report

During recent years, the multiprocessor system M5Ps with up to eight processor modules, connected to a common memory via a time-shared bus, has been designed and realized. The authors present results with regard to the influence of bus allocation strategies. First a general approach proposes an optimum strategy for minimum execution times based on the process-dependent total demand of service time and the processor-processor-dependent bus request rates. Secondly, several allocation strategies are investigated by means of queueing models and estimations. A comparison of both shows that the requirements of the optimum strategy cannot be accomplished by the realized ones due to hardware restrictions. This leads to some criteria for the best possible bus allocation algorithm. Finally these results are demonstrated by some measured examples. 6 references.