Approximating closed fork-join queueing networks using product-form stochastic Petri-nets
Rasha Osman, Peter G. Harrison
Journal of Systems and Software
Computing paradigms have shifted towards highly parallel processing and massive replication of data. This entails the efficient distribution of requests and the synchronization of results provided to users. Guaranteeing SLAs requires the ability to evaluate the performance of such systems while taking the effect of non-parallel workloads into consideration. This can be achieved with performance models that are able to represent both parallel and sequential workloads. This paper presents a
... t-form stochastic Petri-net approximation of fork-join queueing networks with interfering requests. We derive the necessary conditions that guarantee the accuracy of the approximations and verify this through examples in comparison to simulation. We apply these approximate models to the performance evaluation of replication in NoSQL cloud datastores and illustrate the composition of large models from smaller models, thus facilitating the ability to model a range of deployment scenarios. We show the efficiency of our solution method, which finds the product-form solution of the models without the representation of the state-space of the underlying CTMC. He has researched into stochastic performance modelling and algebraic program transformation for some thirty five years, visiting IBM Research Centers during two summers. He has written two books, had over 200 research papers published and held a series of research grants, both national and international. The results of his research have been exploited extensively in industry, forming an integral part of commercial products such as Metron's Athene Client-Server capacity planning tool. Currently, his main research interests are in stochastic modelling, where he has developed the RCAT methodology for finding separable solutions, Hidden Markov Models, response time analysis and modulated fluid models, together with applications such as storage systems, resource virtualization and energy-saving. He has taught a range of subjects at undergraduate and graduate level, including Operating Systems: Theory and Practice, Functional Programming, Parallel Algorithms and Performance Analysis.