Strategies for organizing the two copies of data in the context of database applications are compared. The effects of small and large stripe sizes on the performance of disk arrays with two active copies of data under...
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Strategies for organizing the two copies of data in the context of database applications are compared. The effects of small and large stripe sizes on the performance of disk arrays with two active copies of data under a mixed workload of queries and transactions with a skewed access pattern are considered. A dual striping strategy which uses different stripe sizes for the two copies is proposed. An analytical performance model is devised for this scheme, and the results are shown to match well with simulation data. Comparison with uniform striping strategies shows that the dual striping scheme yields the most stable performance in a variety of workloads.< >
Workload management algorithms for satisfying administration defined response time goals in transaction processing systems are presented. Each arriving transaction belongs to a predefined transaction class, and the sy...
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Workload management algorithms for satisfying administration defined response time goals in transaction processing systems are presented. Each arriving transaction belongs to a predefined transaction class, and the system administrator defines an average response time goal for each transaction class. A dynamic transaction priority algorithm and a set of transaction routing algorithms for multiple processor transaction systems are given. These algorithms set priorities and route transactions based on the data objects accessed by the transactions, the current load of each system, and the goal satisfaction of the transaction classes. The algorithms have low overhead, and a detailed simulation study shows that they substantially improve goal satisfaction compared to previous work.< >
The performance of a paralleldistributed detection system is investigated as the number of sensors tends to infinity. It is assumed that the i.i.d. sensor data are quantized locally into m-ary messages and transmitte...
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The performance of a paralleldistributed detection system is investigated as the number of sensors tends to infinity. It is assumed that the i.i.d. sensor data are quantized locally into m-ary messages and transmitted to the fusion center for Bayesian binary hypothesis testing. Large deviations techniques are employed to show that the equivalence of absolutely optimal and best identical-quantizer systems is not limited to error exponents, but extends to the actual Bayes error probabilities up to a multiplicative constant. This is true as long as the two hypotheses are mutually absolutely continuous; no further assumptions, such as boundedness of second moments of the post-quantization log-likelihood ratio, are needed.
A class of dynamic systems consisting of constrained planar rigid bodies is considered. This class of environments poses two significant challenges to the development of advanced kinesthetic interfaces. First, the env...
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A class of dynamic systems consisting of constrained planar rigid bodies is considered. This class of environments poses two significant challenges to the development of advanced kinesthetic interfaces. First, the environment structure changes dynamically due to collisions between bodies. Thus, the equations of motion must be formulated and solved in real-time. second, the equations are necessarily stiff due to rigid constraints in the system. Thus, real-time simulation requires extremely high update rates to be stable and present the operator with a realistic "feel".< >
The following topics are dealt with: parallel processing of database operations;parallel machines;parallel joins;parallel algorithms;distributedsystems;and distributed query processing.
ISBN:
(纸本)0818620528
The following topics are dealt with: parallel processing of database operations;parallel machines;parallel joins;parallel algorithms;distributedsystems;and distributed query processing.
Replication is a common method for increasing the availability of data in a distributed environment. Our interest is in the application of replication techniques in the domain of parallel processing. This paper explor...
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ISBN:
(纸本)0818626720
Replication is a common method for increasing the availability of data in a distributed environment. Our interest is in the application of replication techniques in the domain of parallel processing. This paper explores the issues concerning degree of replication and granularity in the context of a distributed and highly available Linda tuple space. In particular, we study the performance effects of varying the number of replicas and the granularities of replication and concurrency control. Traditionally, when using replication in databases, the granularity of replication and that of concurrency control have been the same (at the file level, for example). This is not an inherent requirement however. In this paper we show by detailed simulation of a replicated Linda tuple space that it is useful to separate the two granularities and that it is an important design issue especially in parallel processing systems.
A dual-level dynamic load distribution strategy is proposed for allocating parallel computations with unpredictable structures to hypercube based distributedsystems. Computations with dynamic structures represent a w...
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Traditionally, register files have been the primary agent for inter-operation communication in load/store architectures. As processors start issuing multiple instructions per cycle, a centralized register file can eas...
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ISBN:
(纸本)0818631759
Traditionally, register files have been the primary agent for inter-operation communication in load/store architectures. As processors start issuing multiple instructions per cycle, a centralized register file can easily become a bottleneck. This paper analyzes the register file traffic in a load/store architecture with a view to motivate the development of alternate inter-operation communication mechanisms that reduce the bandwidth demanded of a centralized register file. We first provide metrics to characterize the register traffic. These metrics deal with the degree and locality of use of the register instances created. We then present the results of a simulation study that uses the MIPS R2000 architecture and the SPEC benchmark programs. We have two major results. First, a large number of the register instances are used only once, and the average degree of use of register instances is about 2. second, most of the register instances are used up soon after they are created (within about 30-40 instructions). This suggests that alternate inter-operation communication mechanisms that exploit the temporal locality of use of register instances are likely to be effective in reducing the traffic burden on the centralized register file. The second result was pivotal in the design of the distributed register file for the multiscalar processing paradigm.
Termination detection is a fundamental problem in distributed computing. Many algorithms have been proposed, but only the Chandrasekaran and Venkatesan (CV) algorithm is known to be optimal in worst-case message compl...
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ISBN:
(纸本)0818626720
Termination detection is a fundamental problem in distributed computing. Many algorithms have been proposed, but only the Chandrasekaran and Venkatesan (CV) algorithm is known to be optimal in worst-case message complexity. This optimal algorithm, however, has several undesirable properties. First, it always requires M′+2*|E|+n-1 control messages, whether it is worst case or best case, where M′ is the number of basic messages issued by the underlying computation after the algorithm starts, |E| is the number of channels in the system, and n is the number of processes. second, its worst-case detection delay is O(M′). In a message-intensive computation, that might not be tolerable. Third, the maximum amount of space needed by each process is O(M′), a quantity not known at compile time, making it necessary to use the more expensive dynamic memory allocation. Last, it works only for FIFO channels. The purpose of this paper is to remedy these drawbacks, while keeping its strength. We propose an algorithm that requires M′+2(n-1) control messages in the worst case, but much fewer on the average, and in the best case, it uses only 2(n-1) control messages, no matter how large M′ is. The worst-case detection delay is O(n), as compared to the CV-algorithm's O(M′);and the space complexity is Θ(n) for each process, a compile-time known quantity. The algorithm works equally well for both FIFO and Non-FIFO channels.
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