Browsing by Author "Unger, Brian W."
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Item Open Access A Fast-time simulation of air-traffic control(1988) Inkster, James A.; Unger, Brian W.Item Open Access A generic execution management framework for long running jobs in grid environments(2012) Elahi, Tanvire; Simmonds, Robert William John; Unger, Brian W.Over the last decade, the grid has emerged as a paradigm of distributed and collaborative computing focusing on the sharing of computational and storage resources spanning across geographical and organizational domains. Greater access to high-end computational facilities provides researchers fom a broad spectrum of domains an inexpensive option of carrying out sophisticated computational experiments. However, the inherent dynamics and heterogeneity of grid environments make the execution of resource and compute intensive applications a challenging task. Increasing fault tolerance by checkpointing and migrating jobs between resources requires significant expertise and intervention from users. Automation of such tasks can allow them to focus more on the scientific results and less on the technical details. This thesis addresses the issues associated with management of execution of long running applications in grid environments. It presents a generic framework for automating execution of such applications. The framework is driven by a set of information models that capture knowledge about the resources and the applications. Crucial to the functioning of the framework is information on two application characteristics: the configurability, and the memory usage behaviour. Separate models are presented to encode knowledge of both of these characteristics. Use of a common representation of knowledge abstracts the heterogeneity of both the resources and the applications and makes the framework functional without the need to be tailored to any specific application. Two important issues that need to be considered in managing job execution are the amount of memory required by the job and the wait time the job may experience on a specific resource. The framework presented in this thesis is equipped with mechanisms to address both of these issues. It is able to make estimations about the wait time for jobs with different resource requirements. A learning system has been designed as part of the framework to characterize the memory usage behaviour of application instances. The system facilitates execution management operations by providing accurate estimation of job's memory usage.Item Open Access A gridFTP overlay network service(2006) Rizk, Philip; Unger, Brian W.; Simmonds, Robert William JohnItem Open Access A model for multimedia orchestration(1995) Robbins, Robert Wayne; Unger, Brian W.Item Embargo A Modular design and implementation of the Unix operating system(1979) Mutalik, P. R.; Unger, Brian W.Item Open Access A TCP toolkit for network simulation and emulation(2005) Taleb, Hala A.; Unger, Brian W.Item Open Access An object oriented framework for the simulation of network models(1999) Damian, Adrian; Unger, Brian W.Item Open Access CSP*--a distributed logic programming language for discrete event simulation(1989) Li, Xining; Unger, Brian W.Item Embargo Distributed software prototyping and simulation(1984) Lomow, Greg A. (Gregory Alexander), 1960-; Unger, Brian W.Item Open Access Effects of per-VC queueing and buffer management on TCP over ATM performance(1999) Zhu, Jiayun; Unger, Brian W.Item Open Access Internet traffic model toolkit(2001) Doerksen, Julie; Unger, Brian W.Item Embargo Language design to support system sofware development(1980) Parker, J. R.; Unger, Brian W.Item Open Access Object oriented simulation for queueing systems(1997) Li, Xiaoming; Unger, Brian W.Item Open Access Optimising time warp: lazy rollback and lazy reevaluation(1988) West, Darrin; Unger, Brian W.Item Open Access Optimizing incremental state saving and restoration(1996) Gomes, Fabian A. F. B.; Unger, Brian W.; Cleary, John G.Item Open Access Performance modeling of mobile multicasting protocols(1999) Banadaki, Seyed Jafar Shafaeddin; Unger, Brian W.Item Open Access Reinforcement learning in neural nets(1988) Schack, Brian; Unger, Brian W.Item Open Access Scalable network emulation(2004) Kiddle, Cameron; Unger, Brian W.Network emulation provides a testing environment where real network protocols and applications running on real network hosts can interact under controlled and repeatable network conditions. One approach to emulation involves simulating a network model, called the virtual network, with a real-time network simulator and providing an I/O interface that enables interaction between real hosts and the virtual network. To reflect the behavior of large networks such as the Internet it is important that the emulation environment be scalable. The virtual network must be able to scale in size and in traffic volume and the I/O interface must be able to scale in the number of real hosts and in real traffic volume. This thesis focuses on addressing scalability of the virtual network through the use of various simulation techniques. Parallel simulation techniques are employed in both shared memory and distributed memory environments. A simulation abstraction technique is also introduced that allows for the interaction of packet-based traffic flows and fluid-based traffic flows. With only parallel simulation techniques employed, real-time emulation performance of nearly 50 million packet transmissions per second is achieved on 128 processors for a network model consisting of about 20,000 nodes. With all simulation techniques employed, real-time emulation performance of nearly 500 million packet transmissions per second is achieved on 128 processors for a network model consisting of about 200,000 nodes.Item Open Access Sequential performance of PDES algorithms(2005) Curry, Roger J.; Unger, Brian W.Item Embargo Simulation model for housing policy impact analysis(1976) Merlino, Gianfranco; Unger, Brian W.