The analysis and simulation of multi-access computer systems

Digitisation of this thesis was sponsored by Arcadia Fund, a charitable fund of Lisbet Rausing and Peter Baldwin

A comparative study of three simulation languages as applied to manufacturing facility simulation

A study was conducted to compare and evaluate the three prominent simulation languages; GPSS/H, SLAM, and SIMSCRIPT II.5. The main objective of the research was to identify the most appropriate language among the three as applied to manufacturing facility simulation. The most important qualitative features of the three languages were discussed and compared based on a pre-defined set of criteria. The performances of the three languages were evaluated based on another set of criteria. A hypothetical model of a manufacturing facility was used for the evaluation. An experiment was designed to measure the performances of the languages under different conditions. Three model configurations and five different simulation periods were considered in the design of the experiment. Intensive statistical analyses were conducted to analyze the results that were collected from the various trials of the simulation models;In all the cases that were considered in the experiment, GPSS was found to be the most appropriate language among the three. In comparison of period lengths and scale of model, it compiled and executed faster, it used less CPU and memory time, and the rates of change in execution, CPU, and memory times variables were much less than those of the other two languages due to increases in the simulation period and to enlargements in the model size

Performance measurement and evaluation of time-shared operating systems

Time-shared, virtual memory systems are very complex and changes in their performance may be caused by many factors - by variations in the workload as well as changes in system configuration. The evaluation of these systems can thus best be carried out by linking results obtained from a planned programme of measurements, taken on the system, to some model of it. Such a programme of measurements is best carried out under conditions in which all the parameters likely to affect the system's performance are reproducible, and under the control of the experimenter. In order that this be possible the workload used must be simulated and presented to the target system through some form of automatic workload driver. A case study of such a methodology is presented in which the system (in this case the Edinburgh Multi-Access System) is monitored during a controlled experiment (designed and analysed using standard techniques in common use in many other branches of experimental science) and the results so obtained used to calibrate and validate a simple simulation model of the system. This model is then used in further investigation of the effect of certain system parameters upon the system performance. The factors covered by this exercise include the effect of varying: main memory size, process loading algorithm and secondary memory characteristics

The Distributed Independent-Platform Event-Driven Simulation Engine Library (DIESEL)

The Distributed, Independent-Platform, Event-Driven Simulation Engine Library (DIESEL) is a simulation executive, capable of supporting both sequential and distributed discrete-event simulations. A system level specification is provided along with the expected behavior of each component within DIESEL. This behavioral specification of each component, along with the interconnection and interaction between the different components, provides a complete description of the DIESEL behavioral model. The model provides a considerable amount of freedom for an application developer to partition the simulation model, when building sequential and distributed applications with respect to balancing the number of events generated across different components. It also allows a developer to modify underlying algorithms in the simulation executive, while causing no changes to the overall system behavior so long as the algorithms meet the behavioral specifications. The behavioral model is object-oriented and developed using a hierarchical approach. The model is not targeted towards any programming language or hardware platform for implementation. The behavioral specification provides no specifics about how the model should be implemented. A complete and stable implementation of the behavioral model is provided as a proof-of-concept, and can be used to develop commercial applications. New and independent implementations of the complete model can be developed to support specific commercial and research efforts. Specific components of the model can also be implemented by students in an educational environment, using strategies different from the ones used within the current implementation. DIESEL provides a research environment for studying different aspects of Parallel Discrete-Event Simulation, such as event management strategies, synchronization algorithms, communication mechanisms, and simulation state capture capabilities