Bharadwaj Veeravalli

• National University of Singapore

This paper investigates the problem of scheduling multiple divisible loads in networked computer systems with a particular emphasis in capturing two important real-life constraints, the arbitrary processor release times (or ready times) and heterogeneous processing requirements of different loads. We study two distinct cases of interest, static cas...

In this paper we propose a novel high-performance algorithm, referred to as MARSs (Matrix Algorithm for RNA Secondary Structure Prediction), for predicting RNA Secondary Structures with or without pseudoknots. The algorithm is capable of operating in both serial and parallel modes. The algorithm will take complete advantage of the explicit hardware...

Scheduling multisource divisible loads is a challenging task as different sources should cooperate and share their computing power with others to balance their loads and minimize total computational time. In this study, we attempt to address a generalized divisible load scheduling problem for handling loads from multiple sources on arbitrary networ...

RNA structure prediction problem is a computationally complex task, especially with pseudo-knots. The problem is well-studied in existing literature and predominantly uses highly coupled Dynamic Programming (DP) solutions. The problem scale and complexity become embarrassingly humungous to handle as sequence size increases. This makes the case for...

In this paper, we evaluate and compare the performance of several spanning tree routing strategies for divisible load scheduling on arbitrary graphs and derive recommendations as to which routing strategy provides a better trade-off between complexity and time performance. We consider a network comprising heterogeneous processors interconnected by...

In this paper, we address the biological sequence alignment problem, which is one of the most commonly used steps in several bioinformatics applications. We employ the Divisible Load Theory (DLT) paradigm that is suitable for handling large-scale processing on network-based systems to achieve a high degree of parallelism. Using the DLT paradigm, we...

This paper considers the scheduling of exams for a set of university courses. The solution to this exam timetabling problem involves the optimization of complete timetables such that there are as few occurrences of students having to take exams in consecutive periods as possible but at the same time minimizing the timetable length and satisfying ha...

The discrete wavelet transform (DWT) is a powerful signal processing tool, but comes with a considerable computation cost. In this paper, we consider the problem of parallelizing the DWT computation on loosely-coupled networked systems. We first systematically analyze the data dependencies among DWT computations, identify the partitionable portions...

In this paper, we present a generalized and novel load distributionstrategy for scheduling divisible loads on linear networks, whenspeeds of the computing nodes and the communication links are unknowna priori. This strategy, which is referred to as Wait and ComputeStrategy (WCS), uses a portion of the total load to estimate speedparameters and then...

In this paper, we consider the problem of processor allocation on mesh-based multiprocessor systems. We employ the idea of using migration to minimize fragmentation and the overall processing time of the tasks. In our schemes, we consider the use of task migration whenever required to improve the problem of fragmentation. To this end, we propose th...

In this paper, we consider the problem of scheduling multiple divisible loads on heterogeneous linear daisy chain networks. Our objective is to design a load distribution strategy such that the total processing time of a set of loads is minimized. We assume that the set of loads are resident in one of the farthest end processors, which has a schedu...

Interactions between Transcription Factors (TFs) are necessary for deciphering the complex mechanisms of transcription regulation in eukaryotes. We proposed a novel HV-kernel based SVM classifier to classify TF-TF pairs based on their protein domains and GO annotations. Two types of pairwise kernels, namely, a horizontal kernel and a vertical kerne...

In this paper, we propose a heuristic static energy-aware scheduling algorithm for scheduling tasks with precedence constraints on a heterogeneous multiprocessor embedded system consisting of processing elements equipped with dynamic voltage scaling capabilities. While most energy-aware scheduling algorithms in the literature assume that the mappi...

In this paper, we propose distributed algorithms referred to as resource-aware dynamic incremental scheduling (RADIS) strategies. Our strategies are specifically designed to handle large volumes of computationally intensive arbitrarily divisible loads submitted for processing at cluster/grid systems involving multiple sources and sinks (processing...

Interactions between transcription factors (TFs) are necessary for deciphering the complex mechanisms of transcription regulation in eukaryotes. In this paper, we proposed a novel HV-kernel based Support Vector Machine classifier (HV-SVM) to predict TF-TF interactions based on their protein domain information and GO annotations. Specifically, two t...

In this paper, we propose load distribution strategies for divisible loads for networked computing environments where computation and communication resource characteristics are unknown and/or vary with time. The principle on which our strategies are formulated is based on using probing loads to estimate the network characteristics and using them to...

Large-scale distributed applications are subject to frequent disruptions due to resource contention and failure. Such disruptions are inherently unpredictable and, therefore, robustness is a desirable property for the distributed operating environment. In this work, we describe and evaluate a robust topology for applications that operate on a spann...

Media streaming is a promising technology which enables fast and adaptive delivery of media contents and allows clients to view videos online without waiting for the entire multimedia files to be completely downloaded. In this paper, we address the issue of streaming quality measurement and assessment over a large scale network. We propose a multia...

Grid computing holds the great promise to effectively share geographically distributed heterogeneous resources to solve large-scale complex scientific problems. One of the distinct characteristics of the Grid system is resource heterogeneity. The effective use of the Grid requires an approach to manage the heterogeneity of the involved resources th...

Biological research frequently requires specialist databases to support in-depth analysis about specific subjects. With the rapid growth of biological sequences in public domain data sources, it is difficult to keep these databases current with the sources. Simple queries formulated to retrieve relevant sequences typically return a large number of...

Several works on multimedia storage appear in literature today, but very little if any, have been devoted to handling long duration video retrieval, over large scale networks. Distributed retrieval of multimedia documents, especially the long duration documents, is an imperative step in rendering high-quality, high-fidelity, and cost-effective serv...

In this paper, we design a multiprocessor strategy that exploits the computational characteristics of the algorithms used for biological sequence comparison proposed in the literature. We employ divisible load theory (DLT) that is suitable for handling large scale processing on network based systems. For the first time in the domain of DLT, the pro...

Video-on-demand (VoD) applications place very high requirements on the delivery medium. High-quality services should provide for a timely delivery of the data-stream to the clients plus a minimum of playback disturbances. The major contributions of this paper are that it proposes a multiserver, multi-installment (MSMI) solution approach (sending th...

In this paper, we consider the problem of scheduling divisible loads on arbitrary graphs with the objective to minimize the total processing time of the entire load submitted for processing. We consider an arbitrary graph network comprising heterogeneous processors interconnected via heterogeneous links in an arbitrary fashion. The divisible load i...

The problem of distributing and processing a divisible load in a heterogeneous linear network of processors with arbitrary processors release times is considered. A divisible load is very large in size and has computationally intensive CPU requirements. Further, it has the property that the load can be partitioned arbitrarily into any number of por...

In this paper, the problem of scheduling divisible loads on arbitrary tree networks is considered, with the objective to minimize the total processing time of the entire load. We consider an arbitrary tree network comprising heterogeneous processors interconnected via heterogeneous links. The divisible load is assumed to originate at the root proce...

Wavelength division multiplexing (WDM) has emerged as a promising technology for use in backbone transport networks. In an IP/WDM network, the optical layer provides circuit-switched lightpath services to the client Internet protocol (IP) layer. The set of all the lightpaths in the optical layer defines the virtual topology. Since the optical switc...

Divisible load theory is a methodology involving the linear and continuous modeling of partitionable computation and communication loads for parallel processing. It adequately represents an important class of problems with applications in parallel and distributed system scheduling, various types of data processing, scientific and engineering comput...

In this paper, we apply divisible load theory to model the Grid scheduling problem involving multiple sources to multiple sinks, and present an optimized scheduling tech-nique for this scenario. This scheduling technique can be easily extended to schedule resources with buffer space constraints. We provide a step-wise scheduling algorithm for these...

In this paper, we present a theoretical and an experimental study on the problem of scheduling the processing of a very large size image on a cluster of processors interconnected via a bus network. We use the divisible load paradigm, referred to as divisible load theory (DLT), to schedule the entire processing of an image onto the processors. The o...

The problem of scheduling multiple divisible loads on bus networks is addressed in this paper. The objective is to minimize the total processing time of all the divisible loads submitted to the system for processing. A heterogeneous system of processors in the network is considered, and strategies that minimize the total processing time of multiple...

We investigate the performance of a network system on the World-Wide Web employing proxies that interact with a pool of servers to service a pool of client requests. We focus on modelling the interaction of a proxy with the server system and its performance in maximizing the number of requests that can be served. We formulate the problem using a di...

We present a performance analysis and experimental simulation results on the problem of scheduling a divisible load on a bus network. In general, the computing requirement of a divisible load is CPU intensive and demands multiple processing nodes for efficient processing. We consider the problem of scheduling a very large matrix–vector product comp...

Wavelength-division multiplexed (WDM) networks using wavelength routing are emerging to be the right choice for the future transport networks. In a WDM-based transport network, the optical layer provides circuit-switched lightpath services to the client layer such as IP, SONET, and ATM. The set of lightpaths in the optical layer defines the virtual...

Scheduling a divisible load on a heterogeneous single-level tree network with processors having finite-size buffers is addressed. We first present the closed-form solutions for the case when the available buffer size at each site is assumed to be infinite. Then we analyze the case when these buffer sizes are of finite size. For the first time in th...

Optimal distribution of divisible loads in bus and linear networks is considered in this paper. The problem of minimizing the processing time is investigated by including all the overhead components that could penalize the performance of the system, in addition to the inherent communication and computation delays. In the case of bus networks, close...

We investigate the data partitioning, distribution, and scheduling problem for minimizing the total processing time of computer vision and image processing (CVIP) data on bus networks. Using the recently evolved divisible load paradigm (DLT) [V. Bharadwaj, D. Ghose, V. Mani, T.G. Robertazzi, Scheduling divisible loads in parallel and distributed sy...

This book provides an in-depth study concerning a claqss of problems in the general area of load sharing and balancing in parallel and distributed systems. The authors present the design and analysis of load distribution strategies for arbitrarily divisible loads in multiprocessor/multicomputer systems subjects to the system constraints in the form...

The problem of processing divisible loads in a distributed bus network architecture with arbitrary processor available/release times is considered. The objective is to optimally distribute the load among the processors in the system in such a way that the processing time of the entire load is a minimum. Different cases of release time distributions...

In this paper, we present an improved load distribution strategy, for arbitrarily divisible processing loads, to minimize the processing time in a distributed linear network of communicating processors by an efficient utilization of their front-ends. Closed-form solutions are derived, with the processing load originating at the boundary and at the...

This paper presents a new strategy for load distribution in a single-level tree network equipped with or without front-ends. The load is distributed in more than installment in an optimal manner to minimize the processing time. This is a deviation and an improvement over earlier studies in which the load distribution is done in only one installment...

The problem of obtaining optimal processing time in a distributed computing system consisting of (N+1) processors and N communication links, arranged in a single-level tree architecture, is considered. It is shown that optimality can be achieved through a hierarchy of steps involving optimal load distribution, load sequencing, and processor-link ar...