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Title: A compositional approach to performance modelling
Author: Hillston, Jane
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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Performance modelling is concerned with the capture and analysis of the dynamic behaviour of computer and communication systems. The size and complexity of many modern systems result in large, complex models. A compositional approach decomposes the system into subsystems that are smaller and more easily modelled. In this thesis a novel compositional approach to performance modelling is presented. This approach is based on a suitably enhanced process algebra, PEPA (Performance Evaluation Process Algebra). The compositional nature of the language provides benefits for model solution as well as model construction. An operational semantics is provided for PEPA and its use to generate an underlying Markov process for any PEPA model is explained and demonstrated. Model simplification and state space aggregation have been proposed as means to tackle the problems of large performance models. These techniques are presented in terms of notions of equivalence between modelling entitles. A framework is developed for analysing such notions of equivalence and it is explained how the bisimulation relations developed for process algebras fit within the framework. Four different equivalence relations for PEPA, two structural and two based on bisimulation are developed and considered within this framework. For each equivalence the implications for the underlying Markov process are studied and its potential use as the basis of a model simplification technique is assessed. Three of these equivalences are shown to be congruences and all are complementary to the compositional nature of the models considered. As well as their intrinsic interest from a process algebra perspective, each of these notions of equivalence is also demonstrated to be useful in a performance modelling context. The strong structural equivalence, isomorphism, generates equational laws which form the basis of model transformation techniques. This is weakened to define weak isomorphism.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available