Conservative parallel simulation protocols are such that each logical process (LP) in the simulation execute events only when it is certain that there will not be any time-order causality violation. In these conservat...
ISBN:
(纸本)0818691948
Conservative parallel simulation protocols are such that each logical process (LP) in the simulation execute events only when it is certain that there will not be any time-order causality violation. In these conservative protocols, time-bound information for an LP is computed from the other LPs. In this paper we propose a variant form of conservative parallel simulation protocol in which the time-bound for an LP is computed from the existing events in the system. In a conservative protocol such as the Chandy-Misra-Bryant (CMB) protocol, it can be difficult for LPi to guarantee different time-bounds to its next LPs. the time-bounds to some LPs may be more restrictive than necessary. If the time-bounds are provided by the entities (events) going through the system (as in our proposed algorithm,), an event E at LPi can independently supply different time-bounds only to those LPs which may receive events generated by E. We will describe the algorithm, outline a proof of its correctness and discuss its possible strengths and weaknesses.
An efficient design of the interconnection network is crucial because of its impact on the parallel computer performance. A high speed routing scheme that minimises contention and avoids the formation of hot-spots sho...
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ISBN:
(纸本)0818691948
An efficient design of the interconnection network is crucial because of its impact on the parallel computer performance. A high speed routing scheme that minimises contention and avoids the formation of hot-spots should be included in the design. We have developed a new method to uniformly balance communication traffic over the interconnection network called distributed Routing Balancing (DRB) that is based on limited and load-controlled path expansion in order to maintain a low message latency. the method uniformly distributes the communication load between all links of the interconnection network and maintains latency controlled provided that total bandwidth requirements do not exceed total available link bandwidth in the interconnection network. DRB defines how to create alternative paths to expand single paths (expanded path definition) and when to use them depending on traffic load (expanded path selection carried out by DRB Routing). Some conclusions of the experimentation and comparisons with existing methods are done. It is demonstrated that DRB is a method to effectively balance network traffic.
With increased data rates, the packet transmission time of a LAN could approach or even become less than the medium propogation delay Performance of many LAN schemes degrades rapidly tinder these conditions. Generally...
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ISBN:
(纸本)0818691948
With increased data rates, the packet transmission time of a LAN could approach or even become less than the medium propogation delay Performance of many LAN schemes degrades rapidly tinder these conditions. Generally. the overhead associated with medium access protocol increases withthe increase in propogation time relative to packet transmission time. In token ring networks this overhead depends on the round trip propogation delay of the channel. Several schemes, such as multiple rings (with multiple channels) and multiple access points (with multiple tokens) are proposed to decrease this overhead In these schemes analytical and simulation results have shown improved performance. In the present paper we propose a distributed multiconnected loop topology with multiple tokens. WE also present analytical results showing the packet delay performance. Finally we compare the performance of distributed multiconnected loops with multiple ring topology in terms of media access control, taken coalescence and delay.
Object-relational databases management systems (OR-DBMS) extend the capabilities of the relational databases by allowing definition of new data types and methods to operate on these data types while retaining most of ...
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ISBN:
(纸本)0818691948
Object-relational databases management systems (OR-DBMS) extend the capabilities of the relational databases by allowing definition of new data types and methods to operate on these data types while retaining most of the relational model semantics. In this paper we examine issues related to parallel processing of queries in object-relational model with respect to efficient storage and retrieval of large objects. We extend the concept of collective I/O and other related techniques like request merging and data sieving in the database domain to achieve high performance in retrieval of large objects. We deal withthe I/O optimization problem in the query executor access methods and the low level runtime system. We also propose a new technique called pooled striping for efficient storage of large objects on multiple disks. the results presented in this paper clearly show the effectiveness of the proposed I/O optimization techniques in handling large amounts of data in a parallel object-relational database system.
In this paper we present a parallel run-time system for the efficient implementation of adaptive applications on distributed memory machines. Our approach is application driven;the target applications are characterize...
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ISBN:
(纸本)3540648097
In this paper we present a parallel run-time system for the efficient implementation of adaptive applications on distributed memory machines. Our approach is application driven;the target applications are characterized by very large variations in time and length scales. Preliminary performance data from parallel unstructured adaptive mesh refinement on an SP machine suggest that the flexibility of our approach does not cause undue overhead.
In this paper, we present a novel framework of a web-based automated parallel CAD environment. the goal of this project is to make available to the CAD community a growing number of design and test applications that s...
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ISBN:
(纸本)0818691948
In this paper, we present a novel framework of a web-based automated parallel CAD environment. the goal of this project is to make available to the CAD community a growing number of design and test applications that support standard interfaces and execute efficiently in a parallel environment. the design files of a user working in a remote machine are transparently shipped to the local Compute Center, the relevant computation is performed in a parallel environment and then the results are returned back to the user. A job submission and scheduling tool ensures proper load balance and maximal usage of the various parallel machines. the whole process is done efficiently and transparently without the user having to bother about any low-level details. At present, a number of parallel CAD tools including a placement tool, a fault simulator and a VHDL simulator are supported. Results from a preliminary implementation are impressive and show the feasibility of the approach.
In this paper we describe the paralld implementation of the Vertex-To-Vertex Radiosity method on a cluster of PC hosts with a distributed Shared Memory interface (DSM). We first explain how we use stochastic rays to c...
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ISBN:
(纸本)3540648097
In this paper we describe the paralld implementation of the Vertex-To-Vertex Radiosity method on a cluster of PC hosts with a distributed Shared Memory interface (DSM). We first explain how we use stochastic rays to compute the Form-Factor. We then proceed to describe the implementation of this method on top of the MILLIPEDE system, a virtual parallel machine that runs on top of available distributed environments. We discuss a step-by-step process for exploiting MILLIPEDE'S optimization mechanisms. Despite the relatively slow communication medium, the optimization process leads from initial slowdown to high speedups.
A distributed, parallel implementation of the widely used Modular Semi-Automated Forces (ModSAF) distributed Interactive Simulation (DIS) is presented, using networked high-performance resources to simulate large-scal...
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ISBN:
(纸本)3540648097
A distributed, parallel implementation of the widely used Modular Semi-Automated Forces (ModSAF) distributed Interactive Simulation (DIS) is presented, using networked high-performance resources to simulate large-scale entity-level exercises. Processing, communication and I/O demands increase dramatically as the simulation grows in terms of size or complexity. A general framework for functional decomposition and scalable communications architecture is presented. An analysis of the communications load within a single computer and between computers is presented. Ongoing activities to address more dynamically communication limitations and processing load using Globus are discussed.
We describe the design and implementation of the distributed Object-Oriented threads System (DOTS). this system is a complete redesign of the distributedthreads System (DTS) using the object-oriented paradigm both in...
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ISBN:
(纸本)3540648097
We describe the design and implementation of the distributed Object-Oriented threads System (DOTS). this system is a complete redesign of the distributedthreads System (DTS) using the object-oriented paradigm both in its internal implementation and in the programming paradigm it supports. DOTS extends the support for fork/join parallel programming from shared memory threads to a distributed environment. It is currently implemented on top of the Adaptive Communication Environment (ACE). A heterogeneous network of Windows NT PC's and of UNIX workstations is transformed by DOTS into a homogeneous pool of anonymous compute servers. DOTS has been used recently in applications from computer graphics and computational number theory. We also discuss the performance characteristics of DOTS for a workstation cluster running under Solaris and a PC network using Windows NT, as they were obtained from a prototypical example.
the need to solve linear systems arising from problems posed on extremely large, unstructured grids has sparked great interest in parallelizing algebraic multigrid (AMG). To date, however, no parallel AMG algorithms e...
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ISBN:
(纸本)3540648097
the need to solve linear systems arising from problems posed on extremely large, unstructured grids has sparked great interest in parallelizing algebraic multigrid (AMG). To date, however, no parallel AMG algorithms exist. We introduce a parallel algorithm for the selection of coarse-grid points, a crucial component of AMG, based on modifica- tions of certain parallel independent set algorithms and the application of heuristics designed to insure the quality of the coarse grids. A prototype serial version of the Mgorithm is implemented, and tests are conducted to determine its effect on multigrid convergence, and AMG complexity.
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