Sensitivity analysis of combined software and hardware performance models: open queueing networks

Contemporary approaches to software performance engineering suffer from weak integration with the design process and provide little feedback to developers. An approach to software performance modelling is presented, based on annotating design specifications with performance parameters and operational analysis of queueing networks representing the hardware. Analytical sensitivity analysis is provided to (1) point out where model refinement and parameter capture effort should be focused, and (2) suggest performance optimisations in the design specification. Sensitivities are obtained by differentiation of the combined software (workload) and hardware performance model. Only open queueing networks are considered at the hardware level. The results are validated, and it is pointed out that further work is particularly needed in the areas of dynamic software performance modelling and distributed systems.