Markovian and analytical models for multiple bus multiprocessor systems with memory blockings

This paper deals with the performance evaluation of asynchronous multiple bus multiprocessor systems where memory modules are temporarily unavailable to processor requests. Such systems cannot be modelled with a product-form queueing network (QN) model because of memory blockings. In this context, we first propose an exact continuous-time Markovian QN model for analyzing small size systems. In order to study medium to large size systems, we also propose several approximate lumped Markovian models and two approximate analytical QN models. The robustness of these approximate models is studied when any memory module gets systematically blocked after each access to this memory module. Results are compared against those obtained either with the exact Markovian QN model or with a stochastic simulation model.