36322621
An improved diffusion algorithm for dynamic load balancing
Abstract Diffusion type algorithms [1, 3, 11] are some of the most popular algorithms for scheduling in dynamic load balancing. It is known however that this type of algorithm can suffer from slow convergence. In this paper the performance of the diffusion type algorithms is improved, while retaining the nearest neighbour communication requirement, through the use of Chebyshev polynomials. It is also proved that both the diffusion algorithm and the improved diffusion algorithm have an optimal property in terms of the amount of load migrated. Numerical results are given comparing the algorithm with the diffusion algorithm as well as a fast algorithm that requires global communication.
14708530
An Evaluation of Sparse Direct Symmetric Solvers: An Introduction and Preliminary Findings
In recent years a number of solvers for the direct solution of large sparse, symmetric linear systems of equations have been developed. These include solvers that are designed for the solution of positive-definite systems as well as those that are principally intended for solving indefinite problems. The available choice can make it difficult for users to know which solver is the most appropriate for their applications. In this study, we use performance profiles as a tool for evaluating and comparing the performance of serial sparse direct solvers on an extensive set of symmetric test problems taken from a range of practical applications.
23412949
An optimal migration algorithm for dynamic load balancing
30629384
Ordering Unsymmetric Matrices into Bordered Block Diagonal Form for Parallel Processing
Large, sparse, unsymmetric systems of linear equations appear frequently in areas such as chemical engineering. One way of speeding up the solution of these linear systems is to solve them in parallel by reordering the unsymmetric matrix into a bordered block-diagonal (BBD) form. A multilevel ordering algorithm is presented in this paper. Numerical results of the algorithm are given to demonstrate that this algorithm gives better orderings than existing algorithms.
40122351
Numerical Experiences with Partitioning of Unstructured Meshes
Abstract The problem of partitioning unstructured meshes for parallel computing is considered. Four existing algorithms as well as a new hybrid algorithm are tested. The numerical results favour the recursive spectral bisection algorithm and the hybrid algorithm. A generalisation of the recursive spectral bisection algorithm to deal with an arbitrary number of processors is discussed.
9413805
A numerical evaluation of sparse direct solvers for the solution of large sparse symmetric linear systems of equations
In recent years a number of solvers for the direct solution of large sparse symmetric linear systems of equations have been developed. These include solvers that are designed for the solution of positive definite systems as well as those that are principally intended for solving indefinite problems. In this study, we use performance profiles as a tool for evaluating and comparing the performance of serial sparse direct solvers on an extensive set of symmetric test problems taken from a range of practical applications.
17520632
Global optimization in clustering using hyperbolic cross points
Erich Novak and Klaus Ritter developed in 1996 a global optimization algorithm that uses hyperbolic cross points (HCPs). In this paper we develop a hybrid algorithm for clustering called CMHCP that uses a modified version of this HCP algorithm for global search and the alternating optimization for local search. The program has been tested extensively with very promising results and high efficiency. This provides a nice addition to the arsenal of global optimization in clustering. In the process, we also analyze the smoothness of some reformulated objective functions.
11464870
Lightweight Monitoring of the Progress of Remotely Executing Computations
The increased popularity of grid systems and cycle sharing across organizations requires scalable systems that provide facilities to locate resources, to be fair in the use of those resources, and to monitor jobs executing on remote systems. This paper presents a novel and lightweight approach to monitoring the progress and correctness of a parallel computation on a remote, and potentially fraudulent, host system. We describe a monitoring system that uses a sequence of program counter values to monitor program progress, and compiler techniques that automatically generate the monitoring code. This approach improves on earlier work by omitting the need to duplicate computation, which both simplifies and reduces the overhead of monitoring. Our approach allows dynamic and accountable cycle-sharing across the Internet. Experimental results show that the overhead of our system is negligible and our monitoring approach is scalable.
47427184
The Performance Impact of Kernel Prefetching on Buffer Cache Replacement Algorithms
A fundamental challenge in improving file system performance is to design effective block replacement algorithms to minimize buffer cache misses. Despite the well-known interactions between prefetching and caching, almost all buffer cache replacement algorithms have been proposed and studied comparatively, without taking into account file system prefetching, which exists in all modern operating systems. This paper shows that such kernel prefetching can have a significant impact on the relative performance in terms of the number of actual disk l/Os of many well-known replacement algorithms; it can not only narrow the performance gap but also change the relative performance benefits of different algorithms. Moreover, since prefetching can increase the number of blocks clustered for each disk I/O and, hence, the time to complete the I/O, the reduction in the number of disk l/Os may not translate into proportional reduction in the total I/O time. These results demonstrate the importance of buffer caching research taking file system prefetching into consideration and comparing the actual disk l/Os and the execution time under different replacement algorithms.
7625528
The performance impact of traffic patterns on routing protocols in mobile ad hoc networks
In this paper, we examine the communication model widely used in simulation studies of mobile ad hoc networks (MANETs). We find that the communication model uses an overly simplistic traffic pattern which restricts the number of connections that originate from each source node to be one or two, and thus the communication model may not represent traffic patterns in many potential applications in MANETs. We then propose a new communication model which extends the previous communication model to include a more general traffic pattern that varies the number of connections per source node. We study the performance impact of traffic patterns on various routing protocols via detailed simulations of a MANET of 112 mobile nodes. Our simulation results show that many of the conclusions drawn in previous protocol comparison studies no longer hold under the new communication model. These results motivate the need for performance evaluation of MANETs to not only include rich and diverse mobility models as has been done in the past but also include diverse traffic patterns that stress a wide set of protocol design issues.
62602047
A self-organizing flock of Condors