parallel Discrete Event simulation (PDES) on a cluster of workstations is a fine grained application where the communication performance can dictate the effiency of the simulation. The high performance Local/System Ar...
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ISBN:
(纸本)0769516084
parallel Discrete Event simulation (PDES) on a cluster of workstations is a fine grained application where the communication performance can dictate the effiency of the simulation. The high performance Local/System Area Networks used in high-end clusters are capable of delivering data with high bandwidth and low latency. Unfortunately, the communication rate far out-paces the capabilities of workstation nodes to handle it (I/O bus, memory bus, CPU resources). For this reason, many vendors are offering a programmable processor on the NIC to allow application specific optimization of the communication path. This invites a new implementation model for distributed applications where: (i) application specific communication optimizations can be implemented on the NIC;(ii) portions of the application that are most heavily communicating can be migrated to the NIC;(iii) some messages can be filtered out at the NIC without burdening the primary processor resources;and (iv) critical events are detected and handled early. The aim of our research is to investigate the utility of this model for PDES and to gain initial experiences in the implementation challenges and potential performance improvement. In this paper, we present our experiences with Early Cancellation - an optimization for Time- Varp that cancels messages in place upon early discovery of a rollback. We believe that there is a large scope for additional optimizations using this model.
Composite events are required for many applications that require obtaining events from various sources, correlating them, and activating appropriate actions. One of the major issues in composite event system is scalab...
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ISBN:
(纸本)0769515886
Composite events are required for many applications that require obtaining events from various sources, correlating them, and activating appropriate actions. One of the major issues in composite event system is scalability. This paper reports on a research that follows the situation concept of the Amit system, and proposes a parallel execution model for the event composition. The paper describes the model and its difficulties, and shows its usefulness using simulation results.
Cycles and knots in directed graphs are problems that can be associated with deadlocks in database and communication systems. Many algorithms to detect cycles and knots in directed graphs were proposed. Boukerche and ...
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ISBN:
(纸本)0769518532
Cycles and knots in directed graphs are problems that can be associated with deadlocks in database and communication systems. Many algorithms to detect cycles and knots in directed graphs were proposed. Boukerche and Tropper have proposed a distributed algorithm that solve the problem in a efficient away. Their algorithm has a message complexity of 2m vs. (at least) 4m for the Chandy and Misra algorithm, where in is the number of links in the graph, and requires 0 (n log n) bits of memory, where n is the number of nodes. We have implemented Boukerche and Tropper's algorithm according to the construction of processes of the CSP model. Our implementation was done. using JCSP, an implementation of CSP for Java, and the results are presented.
Many simulations and other applications need to interact seamlessly with distributed data resources. The Agent-Based Environment for Linking simulations (ABELS) allows the formation of a dynamic "data and simulat...
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ISBN:
(纸本)0769518532
Many simulations and other applications need to interact seamlessly with distributed data resources. The Agent-Based Environment for Linking simulations (ABELS) allows the formation of a dynamic "data and simulation cloud" that links a heterogeneous collection of networked resources. ABELS consists of three major types of components: user entities that serve as data producers and/or consumers, a brokering system for organizing and linking the various participants, and generic local agents that connect simulations and data resources to the cloud of participants. This paper presents the design of the distributed brokering system, which is implemented using Java and Sun Microsystems' Jini technology.
The High Level Architecture allows simulation components Of various hypes to be joined together into a federation to create a common virtual environment. However with the increased complexity of simulations, not all u...
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ISBN:
(纸本)0769518532
The High Level Architecture allows simulation components Of various hypes to be joined together into a federation to create a common virtual environment. However with the increased complexity of simulations, not all user requirements can be satisfied by a flat federation. The requirement of selective information hiding naturally suggests a Hierarchical Federations Architecture (HFA) where federations are organized into hierarchies so that a federation appears as a federate in an upper level federation. In order to provide reusability and interoperability at the federation level, a federation should be able to participate in different super-federations without requiring code modification. In this paper we present an approach to automatically construct the HFA. We describe the information that must be provided by the participating user federations and how this is used to construct the Universal Object Model (UOM) used by the super-FOMs (the FOMs of super-federations). We show how the structure for selective information hiding is generated from the user information and how gateway federates are automatically constructed to support super-FOM independence.
In this paper a not, model for communication in MANETs will be presented. Instead of omnidirectional transmissions, as assumed in most papers and all existing systems, the members are allowed to submit data in a fixed...
ISBN:
(纸本)0769514448
In this paper a not, model for communication in MANETs will be presented. Instead of omnidirectional transmissions, as assumed in most papers and all existing systems, the members are allowed to submit data in a fixed number of different directions (sector subdivision) and to adjust the transmission power in each sector separately. A simulation environment (simulation Environment for Ad Hoc Networks, SAHNE) will be presented that allows simulation of communication strategies in MANETs that use sector subdivision, and simulation results will be shown where communication paths are selected via hop-minimization or geometric spanner properties. SAHNE is based on C++ and common libraries, which ensures that it can be used on many different platforms. The experiments show the influence of different parameters in realistic scenarios, and using geometric routing seemed to be better than using hop-minimization.
A technique called updateable simulations is proposed to reduce the time to complete multiple executions of a discrete event simulation program. This technique updates the results of a prior simulation run rather than...
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We describe a novel approach to scalability and efficiency of parallel network simulation that partitions the networks into domains and simulation time into intervals. Each domain is simulated independently of and con...
This paper presents a scalable architecture for supporting large-scale interactive Internet games. In order to support a large number of participants and to divide the workload, the virtual world is divided into parti...
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There are many mapping schemes proposed in previous research on parallel proxy servers. The operations of these schemes are mainly, URL-based, and therefore cannot fully benefit from the new persistent connection feat...
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ISBN:
(纸本)0769515886
There are many mapping schemes proposed in previous research on parallel proxy servers. The operations of these schemes are mainly, URL-based, and therefore cannot fully benefit from the new persistent connection feature of HTTP/1.1. In this paper, we propose a site-based mapping scheme that forwards all requests targeting on the same web site to the same proxy server. The scheme then allows the proxy to use a single persistent connection to serve many client requests. The major advantage of the scheme is the reduction in the number of connection establish in en is. This reduction can save network bandwidth and reduce the user-experienced latency. simulation results show that the proposed site-based scheme reduces 40%-70% of the connection setups and teardowns when compared to a traditional URL-based mapping scheme.
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