HIPERTRANS (High Performance Transport network modelling and Simulation) is a fast and visually representative simulator that can predict traffic on a given urban road network. It was designed using object-oriented te...
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Our results demonstrate that our novel application development environment provides both ease-of-use and high performance for large-scale, I/O-intensive scientific applications.
ISBN:
(纸本)9781581132700
Our results demonstrate that our novel application development environment provides both ease-of-use and high performance for large-scale, I/O-intensive scientific applications.
This paper focuses on buffer management issues in wormhole-routed torus multicomputer networks. The commonly used buffer organizations are the centralized and dedicated buffer organizations. The results presented in t...
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Network of workstations (NOW) is a cost-effective alternative to a multiprocessor system. Here we propose a centralized architecture for parallel query processing on network of workstations. We describe a three-level ...
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Behavioural and performance analysis is a fundamental problem in the development of parallel (and distributed) programs. To address this problem, models and supporting environments are required to enable designers to ...
Dynamic load sharing policies take system state into account in making load distribution decisions. The state information can be maintained in one of two basic ways: distributed or centralized. Two principal types of ...
Real-time transactions, in addition to preserving consistency of the database as in traditional transactions, have to meet the deadlines. Scheduling real-time transactions in parallel database systems has not received...
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Real-time transactions, in addition to preserving consistency of the database as in traditional transactions, have to meet the deadlines. Scheduling real-time transactions in parallel database systems has not received much attention. This paper focuses on real-time transaction scheduling in shared-nothing parallel database systems. We evaluate the performance of a new priority-based scheduling policy, in which all scheduling decisions are made locally by each node. In contrast, several other algorithms, proposed for the distributed systems, require communication among the nodes to globally synchronize their local block and abort decisions. Such synchronization can deteriorate performance as real-time transactions will have to meet deadlines. We use miss ratio as the performance metric and show that, in general, the new policy provides a superior performance for the workload and system parameters considered in this study.
Networks of workstations (NOWs) are cost-effective alternatives to multiprocessor systems. Recently, NOWs have been proposed for parallel query processing. Idle CPU cycles of workstations in a NOW-based system can be ...
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Networks of workstations (NOWs) are cost-effective alternatives to multiprocessor systems. Recently, NOWs have been proposed for parallel query processing. Idle CPU cycles of workstations in a NOW-based system can be used to process database query operations. We report on the performance of the hierarchical architecture for parallel query processing on a NOW. We have implemented the hierarchical architecture using PVM on a Pentium-based NOW. The experimental results reported suggest that the hierarchical architecture is successful in achieving good scale-ups and speedups indicating that the idle processor cycles are effectively used for query processing. The hierarchical system can also handle both light and heavy workloads in a load sharing fashion. Our results also suggest that the performance is sensitive to the minimum fragmentation size (chunk size) for partial operations and the structure of queries.
Processor scheduling policies for distributed memory systems can be divided into space sharing or time sharing policies. In space sharing, the set of processors in the system is partitioned and each partition is assig...
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Processor scheduling policies for distributed memory systems can be divided into space sharing or time sharing policies. In space sharing, the set of processors in the system is partitioned and each partition is assigned for the exclusive use of a job. In time sharing policies, on the other hand, none of the processors is given exclusively to jobs; instead, several jobs share the processors (for example, in a round robin fashion). There are advantages and disadvantages associated with each type of policy. Typically, space sharing policies are good at low to moderate system loads and when job parallelism does not vary much. However, at high system loads and widely varying job parallelism, time sharing policies provide a better performance. We propose a new policy that is based on a hierarchical organization that incorporates the merits of these two types of policies. The new policy is a hybrid policy that uses both space sharing as well as time sharing to achieve better performance. We demonstrate that, at most system loads of interest, the proposed policy outperforms both space sharing and time sharing policies by a wide margin.
A common technique to improve the reliability of loop (or ring) networks is by introducing link redundancy; that is, by providing several alternative paths for communication between pairs of nodes. With alternate path...
A common technique to improve the reliability of loop (or ring) networks is by introducing link redundancy; that is, by providing several alternative paths for communication between pairs of nodes. With alternate paths between nodes, the network can now sustain several node and link failures by bypassing the faulty components. However, faults occurring at strategic locations in a ring can prevent the computation by disrupting I/O operations, blocking the flow of information, or even segmenting the structure into pieces which can no longer be suitable for any practical purpose. An extensive characterization of fault-tolerance in ring topologies is given in this paper. This characterization augments the results known in the literature to date. The characterization has revealed several properties which describe the problem of constructing subrings and linear arrays in the presence of node failures in the original ring for a specified link configuration. Also in this paper, bounds are established on the degree of fault tolerance achievable in a redundant loop network, with a given degree of redundancy, when performing a computation that requires a minimal number of operational nodes. Also the bounds on the size of the problems guaranteed to be solved in the presence of a given number of faults in the network are derived.
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