Certain performance aspects of optimal load balancing in distributed computer systems

A distributed computer system is considered to be a collection of autonomous computers (nodes) located at possibly different sites and connected by a communication network. Through the communication network, resources of the system can be shared by users at different locations. Performance enhancement is one of the most important issues in distributed systems. The performance of a distributed computer system can often be improved to an acceptable level by redistributing the workload among nodes. The problem of load redistribution in distributed computer systems is called load balancing. Load balancing policies may be either static or dynamic. Static load balancing policies use only the statistical information on the system (e.g., the average behavior of the system) in making load balancing decisions. On the other hand, dynamic load balancing policies attempt to dynamically balance the workload reflecting the current system state and are therefore thought to be able to further improve the system performance. Generally, the purpose of load balancing policies either static or dynamic is to improve the performance of the system by redistributing the workload among nodes. We can choose between several distinct objectives for performance optimization in many systems including communication networks, distributed computer systems, transportation flow networks, etc. Among them, we have the following three typical objectives or optima: ...Thesis (Ph. D. in Engineering)--University of Tsukuba, (A), no. 3425, 2004.3.25Includes bibliographical reference

Competition in Access to Content

Part 5: Cooperation and CollaborationInternational audienceWe study competition between users over access to content in a telecom market that includes several access providers and several content providers. We focus situations where exclusive agreements exist between content and access providers, which allows access providers to offer content services for free for their subscribers. We call access providers having such agreements ”super” providers or ”enhanced” service providers. We show that the competition between the users results in a paradoxical phenomenon in which subscribers of enhanced providers prefer to defer part of their demand to other content providers whose content is costly. We show how this phenomena can be exploited by the content providers so as to maximize their benefits

A capacity-based load balancing and job migration algorithm for heterogeneous Computational grids", Int

ABSTRAC

Numerical Studies on Braess-Like Paradoxes for Non-Cooperative Load Balancing in Distributed Computer Systems

Distributed computer systems consists of nodes (hosts, computers) and a communication means that connects nodes. Jobs arrive at each node and can be forwarded through the communication means to the other nodes for remote processing. Numerical examples of a Braess-like paradox in which adding capacity to a distributed computer system may degrade the performance of all users in the system have been reported. Unlike the original Braess paradox, in the models examined, this behavior occurs only in the case of finitely many users and not in the case of infinite number of users, and the degree of performance degradation can increase without bound. This study examines numerically, some examples around the Braess-like paradox. From the numerical examples, it is observed that, in the class optimum, the worst ratio of performance degradation in the paradox is largest (i.e., the worst performance is obtained) in the complete symmetry case with the arrival rate is closest to the processing rate. And, as the system parameter setting gradually departs the abovementioned symmetric case without keeping any kind of symmetries, the worst ratio of performance degradation decreases rapidly. It decreases slowly (more slowly) if the system parameter setting departs the complete symmetry while keeping the individual (overall) symmetry property. Indeed, it is also observed that in complete symmetry, if the communication means of type (C) is used, the worst ratio of performance degradation may increase without bound as the arrival rate gets very close to the processing rate