Effect of non-uniform memory request on the performance of buffered multiprocessor systems

Performance analysis of multiple-bus systems is usually carried out under the assumption of a uniform memory request model. Hot spots arising in multiprocessor systems give rise to non-uniform memory requests. It is known that a hot spot memory request pattern results in a signi®cant degradation in the performance of a bu€ered multistage interconnection network. The aim of this research is to study the e€ect of hot spots on the performance of bu€ered multiple-bus systems, and to compare the performance of bu€ered and unbu€ered systems. Analytical models based on Markov chains have been developed to determine the bandwidth of bu€ered multiple-bus systems in the presence of a hot spot memory request pattern. The models assume that unsuccessful memory requests are queued in the bu€ers at the memory modules. Furthermore, processors with outstanding requests are not allowed to generate new requests. The model allows a fast and inexpensive method to evaluate the performance of a bu€ered multiple-bus system in the presence of a hot spot memory request pattern.