RESOURCE ALLOCATION IN COMPUTER NETWORKS (SCHEDULING, CSMA/CD, MULTIPLE BUSES, INTERCONNECTION)

JIE-YONG JUANG, Purdue University

Abstract

In this thesis, we have studied the resource-allocation problem in resource sharing computer systems. A resource sharing computer system is characterized by a pool of request generators and a pool of resources interconnected by a resource sharing interconnection network. Central issues in resource scheduling include the minimization of resource conflicts, the reduction of the probability of network blockage or congestion, and the balance of workload among resources. Evaluations indicated that distributed state-dependent scheduling schemes are preferable. Moreover, integrating the scheduling schemes into the network protocol significantly reduces the overhead of collecting status information. A methodology has been proposed to optimize the resource mapping, reduce the scheduling overhead, and facilitate a fast implementation. The methodology has been applied to design resource-allocation schemes for three representative networks of increasing complexities. For a single contention-bus network, the resource scheduling problem is reduced to the problem of identifying a station with the minimum parameter among a set of physically dispersed random numbers. A distributed minimum-search algorithm that utilizes the collision detection capability of the contention bus has been proposed. The window-search procedure can resolve the global minimum in an average of 2.4 contention steps. No explicit message transfer is required in this process. For a multiple contention-bus network, the resource-allocation problem is reduced to the problem of ordered selections. A multi-window search procedure that is an extension of the single-bus search procedure has been proposed to select the minimum numbers in parallel. The average time complexity of this search procedure is about O(log(,2)t), where t is the number of buses. The mapping between the selected resources and processors has been found to be the classical stable-marriage problem. For resource allocation on multistage interconnection networks, the problem is transformed into different network-flow optimization problems, for which there exists many efficient algorithms. The network-flow algorithms have been integrated into the network protocol with a VLSI systolic-array architecture that allows resource scheduling to be carried out at signal propagation speed.

Degree

Ph.D.

Subject Area

Computer science

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