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A simple load balancing scheme for task allocation in parallel machines
 In Proc. Symposium on Parallel Algorithms and Architectures (SPAA) (1991), ACM
"... A collection of local workpiles (task queues) and a simple load balancing scheme is well suited for scheduling tasks in shared memory parallel machines. Task scheduling on such machines has usually been done through a single, globally accessible, workpile. The scheme introduced in this paper achieve ..."
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Cited by 84 (4 self)
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A collection of local workpiles (task queues) and a simple load balancing scheme is well suited for scheduling tasks in shared memory parallel machines. Task scheduling on such machines has usually been done through a single, globally accessible, workpile. The scheme introduced in this paper achieves a balancing comparable to that of a global workpile, while minimizing the overheads. In many parallel computer architectures, each processor has some memory that it can access more efficiently, and so it is desirable that tasks do not mirgrate frequently. The load balancing is simple and distributed: Whenever a processor accesses its local workpile, it performs a balancing operation with probability inversely proportional to the size of its workpile. The balancing operation consists of examining the workpile of a random processor and exchanging tasks so as to equalize the size of the two workpiles. The probabilistic analysis of the performance of the load balancing scheme proves that each tasks in the system receives its fair share of computation time. Specifically, the expected size of each local task queue is within a small constant factor of the average, i.e. total number of tasks in the system divided by the number of processors. 1
Iterative Dynamic Load Balancing in Multicomputers
 Journal of Operational Research Society
, 1994
"... Dynamic load balancing in multicomputers can improve the utilization of processors and the efficiency of parallel computations through migrating workload across processors at runtime. We present a survey and critique of dynamic load balancing strategies that are iterative: workload migration is car ..."
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Cited by 23 (3 self)
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Dynamic load balancing in multicomputers can improve the utilization of processors and the efficiency of parallel computations through migrating workload across processors at runtime. We present a survey and critique of dynamic load balancing strategies that are iterative: workload migration is carried out through transferring processes across nearest neighbor processors. Iterative strategies have become prominent in recent years because of the increasing popularity of pointtopoint interconnection networks for multicomputers. Key words: dynamic load balancing, multicomputers, optimization, queueing theory, scheduling. INTRODUCTION Multicomputers are highly concurrent systems that are composed of many autonomous processors connected by a communication network 1;2 . To improve the utilization of the processors, parallel computations in multicomputers require that processes be distributed to processors in such a way that the computational load is evenly spread among the processors...
An Adversarial Model for Distributed Dynamic Load Balancing
, 1998
"... We study the problem of balancing the load on processors of an arbitrary network. If jobs arrive or depart during the process of load balancing, we have the dynamic load balancing problem; otherwise, we have the static load balancing problem. While static load balancing on arbitrary and special netw ..."
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Cited by 20 (2 self)
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We study the problem of balancing the load on processors of an arbitrary network. If jobs arrive or depart during the process of load balancing, we have the dynamic load balancing problem; otherwise, we have the static load balancing problem. While static load balancing on arbitrary and special networks has been well studied, very little is known about dynamic load balancing. The difficulty lies in modeling the arrivals and departures of jobs in a clean manner. In this paper, we initiate the study of dynamic load balancing by modeling job traffic using an adversary. Our main result is that a simple, local control distributed load balancing algorithm maintains the load of the network within a stable level against this powerful adversary. Our results hold for different models of traffic patterns and processor communication. 1 Introduction An important problem in a distributed system is to balance the total workload among the various processors of the underlying system. Such load balan...
A Survey of Parallel Search Algorithms for Discrete Optimization Problems
 ORSA JOURNAL ON COMPUTING
, 1993
"... Discrete optimization problems (DOPs) arise in various applications such as planning, scheduling, computer aided design, robotics, game playing and constraint directed reasoning. Often, a DOP is formulated in terms of finding a (minimum cost) solution path in a graph from an initial node to a goal n ..."
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Cited by 10 (0 self)
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Discrete optimization problems (DOPs) arise in various applications such as planning, scheduling, computer aided design, robotics, game playing and constraint directed reasoning. Often, a DOP is formulated in terms of finding a (minimum cost) solution path in a graph from an initial node to a goal node and solved by graph/tree search methods. Availability of parallel computers has created substantial interest in exploring parallel formulations of these graph and tree search methods. This article provides a survey of various parallel search algorithms such as Backtracking, IDA*, A*, BranchandBound techniques and Dynamic Programming. It addresses issues related to load balancing, communication costs, scalability and the phenomenon of speedup anomalies in parallel search.
Abstract Dynamic Load Balancing in Parallel and Distributed Networks
"... The fundamental problems in dynamic load balancing and job scheduling in parallel and distributed computers involve moving load between processors. In this paper, we consider a new model for load movement in synchronous parallel and distributed machines. In each step of our model, each processor ca ..."
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The fundamental problems in dynamic load balancing and job scheduling in parallel and distributed computers involve moving load between processors. In this paper, we consider a new model for load movement in synchronous parallel and distributed machines. In each step of our model, each processor can transfer load to at most one neighbor; also, any amount of load can be moved along a communication link between two processors in one step. This is a reasonable model for load movement in significant classes of dynamic load balancing problems. We derive efficient algorithms for a number of task reallocation problems under our model of load movement. These include dynamic load balancing on pr~ cessor networks, adaptive mesh repartitioning such as those in finite element methods, and progressive job migration under dynamic generation and consumption of load. To obtain the abov~mentioned results, we introduce and solve the abstract problem of Incremental Weight Migration (IWM) on arbitrary graphs. Our main result is a simple, randomized, algorithm for this problem which provably results in asymptotically optimal convergence towards the state where weights on the nodes of the graph are all equal. This algorithm
Efficient Search Algorithms for Tiled Architectures in the Billion Transistor Era
"... Over the next decade the underlying architectural assumptions used in the design of parallel algorithms will change signicantly, likely impacting on the eciency of many wellknown parallel algorithms. Traditionally, parallel algorithms have been designed assuming a few powerful processors interconne ..."
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Over the next decade the underlying architectural assumptions used in the design of parallel algorithms will change signicantly, likely impacting on the eciency of many wellknown parallel algorithms. Traditionally, parallel algorithms have been designed assuming a few powerful processors interconnected by expensive ochip communication links. It is widely known however, that the semiconductor industry roadmap projects that advances in VLSI technology will permit more than one billion transistors on a chip by the year 2010. Several singlechip parallel architectures have been proposed to exploit these chiplevel resources, and to overcome the wiredelay bottleneck apparent in current superscalar designs, designs that do not scale to billion transistor large silicon areas. One of the promising proposed architectures are tiled architectures, based on replicated processing tiles interconnected with highbandwidth, lowoverhead communication links. With the arrival of such negrained, highlyparallel architectures, that possibly provide thousands of simple processing elements connected with fast links, we need to have another look at the eciency of many wellknown parallel algorithms. Search algorithms are among the most fundamental and important algorithms in the eld of computer science. Ecient search algorithms are critical for nding optimal solutions to a wide range of discrete optimization problems. This paper presents an ecient new search algorithm for tiled architectures and highlights some of the main issues when designing algorithms for such systems. Our simulation results show that as the number of tiles increases in a tiled processor, the work distribution in the proposed algorithm becomes signicantly better than in a traditional depthrst search (DFS) al...