K. Vairavan

An experimental investigation of software metrics and their relationship to software development effort

The results are reported of an experimental study of software metrics for a fairly large software system used in a real-time application. A number of issues are examined, including the mutual relationship between various software metrics and, more importantly, the relationship between metrics and the development effort. Some interesting connections are reported between metrics and the software development effort. >

Analysis of a graph coloring based distributed load balancing algorithm

Abstract We present the analysis of a distributed load balancing algorithm based on edge coloring of undirected graphs. One version (linear version) can be studied directly using linear system theory. We show that the performance of another version (integer version), which is more realistic in that the loads are integers, can be studied as a perturbation of the linear version. Both versions of our algorithm converge to stable behavior for arbitrary topologies. In the case of the binary n -cube processor network we prove that after n steps of the integer version, for any initial load distribution, each processor has a load not more than n /2 away from the average.

An Experimental Study of Software Metrics for Real-Time Software

The rising costs of software development and maintenance have naturally aroused intere5t in tools and measures to quantify and analyze software complexity. Many software metrics have been studied widely because of the potential usefulness in predicting the complexity and quality of software. Most of the work reported in this area has been related to nonreal-time software. In this paper we report and discuss the results of an experimental investigation of some important metrics and their relationship for a class of 202 Pascal programs used in a real-time distributed processing environment. While some of our observations confirm independent studies, we have noted significant differences. For instance the correlations between McCabes control complexity measure and Halsteads metrics are low in comparison to a previous study. Studies of the type reported here are important for understanding the relationship between software metrics.

A knowledge-based alarm processor for an energy management system

A novel station-oriented knowledge-based alarm processor prototype is presented. The knowledge-based system accesses a configuration database that contains information on both the topology of the power system and symbolic data values. Forward chaining rules are used to form hypothese when state changes occur on the power system. Backward chaining rules are used then attempt to prove each hypothesis using the current facts and the configuration database. Metalevel control rules improve system performance by selecting goals and doing context switching during the inference process. A rule-based management system is also introduced. The knowledge-based system continuously analyzes and processes SCADA (supervisory control and data acquisition) alarms in real time, presenting diagnostic messages to the power system operators without requiring any information from the operators. The prototype, written in the C programming language, resides on a stand-along computer with a data interface to the SCADA system. >

A receiver-initiated load balancing method in computer networks using fuzzy logic control

We present a receiver-initiated fuzzy logic control method to improve computer network performance by balancing loads among computers. We study and present the performance of this protocol by comparing it with the performance of: (i) a well-known protocol called the BID algorithm; (ii) a non-fuzzy (threshold based) receiver-initiated algorithm; (iii) a fuzzy logic sender-initiated algorithm.

A methodology for evaluating load balancing algorithms

In general, a load balancing algorithm improves a system performance. Obviously, larger the difference between the task arrival rates at various processors, more the system is imbalanced and more improvement in the system performance is achieved using a load balancing algorithm. The existing works which have used an experimental technique to show the improvement in the system performance under a load balancing algorithm have used an ad hoc procedure to select the task arrival rates for various processors. Thus, their experimental results necessarily may not provide a complete picture of the improvement in the system performance under their load balancing algorithms. The authors present a systematic scheme for the selection of the task arrival rates at various processors such that experimental results reflect a complete picture of the improvement in the system performance under a load balancing algorithm. The idea has been motivated by the well-known Taguchi technique used in quality control.<<ETX>>

Scheduling routing table calculations to achieve fast convergence in OSPF protocol

Fast convergence to topology changes is now a key requirement in routing infrastructures while reducing the routing protocol’s processing overhead continues to be as important as before. In this paper, we examine the problem of scheduling routing table updates in link state routing protocols. Commercial routers typically use a hold time based scheme to limit the number of routing table updates as new LSAs arrive at the router. The hold time schemes limit the number of routing table updates at the expense of increased delay in convergence to the new topology, which is clearly not acceptable any more. We analyze the performance of different hold time schemes and propose a new approach to schedule routing table updates, called LSA Correlation. Rather than using individual LSAs as triggers for routing table updates, LSA Correlation scheme correlates the information in the LSAs to identify the topology change that led to their generation. A routing table update is performed when a topology change has been identified. The analysis and simulation results presented in this paper suggest that the LSA Correlation scheme performs much better than the hold time based schemes for both isolated and large scale topology change scenarios.

Performance Characteristics of a Load Balancing Algorithm

The behavior of a graph coloring-based, distributed load balancing algorithm for a network of processors is evaluated in terms of the average response time of the system. A fundamental correspondence between average response time and Euclidean system distance (a measure of load imbalance) is analytically demonstrated. This relationship leads to the proposal of tools intended to be used in the analysis of load balancing methods. Simulation studies were conducted and are found to support the theoretical results.

Stability analysis of a load balancing algorithm

Load balancing is the process of improving the performance of a system through a redistribution of loads among the processors. In this paper the authors present the stability analysis of a load balancing algorithm based on graph coloring. In this algorithm the processors use local knowledge for the purpose of load balancing. Unlike threshold based algorithms whose efficiency depends on the threshold level selected, the graph coloring based load balancing algorithm does not use any such global parameter. Furthermore, it uses the edge coloring concept to pair the processors. This avoids the selection/rejection operations encountered in many load balancing algorithms proposed in the literature. Also, there is no central controller and the algorithm is easily adaptable to changes in the system configurations.

On a load balancing algorithm based on edge coloring

Load balancing is the process of enhancing the performance of a distributed system through a redistribution of loads among the processors. In our earlier work a load balancing algorithm based on graph coloring for link-oriented structures was proposed and studied in detail. In this paper we modify the algorithm by introducing an important factor known as the damping factor, D. This factor is used to strike a balance between the runtime of the algorithm and the average response time. We observe that considerable improvement in system performance is possible with the application of the load balancing algorithm. The primary performance metric used is the average response time of the system. We express the analytical results in terms of upper and lower bounds on the average response time.