Performance by Design: Computer Capacity Planning by Example

Chapter 15. Non Product-Form Queuing Models

Introduction

Most modern computer systems exhibit features that violate the assumptions required by product-form networks. Some system features that violate separable assumptions are: 1) blocking, 2) high service time variability at FCFS centers, 3) simultaneous resource possession, 4) process forking and synchronization, and 5) priority scheduling. These features cannot be modeled directly by product-form models. Thus, many algorithms have been developed to approximate the solution of models that incorporate non product-form features. These algorithms share same basic ideas. They accept a queuing network model that has some nonseparable features and transform it into an approximate network that obeys ...