Person:

Fujimoto, Richard M.

Permanent Link

https://hdl.handle.net/1853/71271

Associated Organization(s)

Organizational Unit

School of Computational Science and Engineering

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Now showing 1 - 9 of 9

Collaborative research: ITR: global multi-scale kinetic simulations of the earth's magnetosphere using parallel discrete event simulation

(Georgia Institute of Technology, 2009-11-30) Fujimoto, Richard M. ; Pande, Santosh ; Perumalla, Kalyan S. ; Omelchenko, Yuri ; Driscoll, Jonathan
Scalable Simulation of Electromagnetic Hybrid Codes

(Georgia Institute of Technology, 2005) Perumalla, Kalyan S. ; Dave, Jagrut Durdant ; Fujimoto, Richard M. ; Karimabadi, Homa ; Driscoll, Jonathan ; Omelchenko, Yuri

New discrete-event formulations of physics simulation models are emerging that can outperform models based on traditional time-stepped techniques. Detailed simulation of the Earth s magnetosphere, for example, requires execution of sub-models that are at widely differing timescales. In contrast to time-stepped simulation which requires tightly coupled updates to entire system state at regular time intervals, the new discrete event simulation (DES) approaches help evolve the states of sub-models on relatively independent timescales. However, parallel execution of DES-based models raises challenges with respect to their scalability and performance. One of the key challenges is to improve the computation granularity to offset synchronization and communication overheads within and across processors. Our previous work was limited in scalability and runtime performance due to the parallelization challenges. Here we report on optimizations we performed on DES-based plasma simulation models to significantly improve their parallel performance. The mapping of model to simulation processes is optimized via aggregation techniques, and the parallel runtime engine is optimized for communication and memory efficiency. The net result of the enhancements is the capability to simulate hybrid particle-in-cell (PIC) model configurations containing over 2 billion particles using 512 processors on supercomputing platforms.
Scalable RTI-Based Parallel Simulation of Networks

(Georgia Institute of Technology, 2003-06) Perumalla, Kalyan S. ; Park, Alfred ; Fujimoto, Richard M. ; Riley, George F.

Federated simulation interfaces such as the High Level Architecture (HLA) were designed for interoperability, and as such are not traditionally associated with high performance computing. In this paper, we present results of a case study examining the use of federated simulations using runtime infrastructure (RTI) software to realize large-scale parallel network simulators. We examine the performance of two different federated network simulators, and describe RTI performance optimizations that were used to achieve efficient execution. We show that RTI-based parallel simulations can scale extremely well and achieve very high speedup. Our experiments yielded more than 80-fold scaled speedup in simulating large TCP/IP networks, demonstrating performance of up to 6 million simulated packet transmissions per second on a Linux cluster. Networks containing up to two million network nodes (routers and end systems) were simulated.
Experiences Applying Parallel and Interoperable Network Simulation Techniques in On-line Simulations of Military Networks

(Georgia Institute of Technology, 2002) Perumalla, Kalyan S. ; Fujimoto, Richard M. ; McLean, Thom ; Riley, George F.

We present a case study in which we apply parallel simulation methods and interoperability techniques to network simulations for simulation-based on-line control of military communication networks. The on-line simulations model actual military networks, including wired shipboard sub-networks connected via satellite links, and wireless mobile devices. The modeled scenario depicts the communication requirements of an amphibious landing where a complex network connects troops ashore and naval vessels. The simulations use a heterogeneous set of tools, including ns2 models for shipboard wired networks, and GloMoSim models for the wireless devices. In this paper, we document the challenges we encountered in applying parallel and interoperable simulation methods, and describe our solutions. We describe our experiences in addressing the interoperability problems that naturally arose due to the heterogeneity of scenario models. We also present a preliminary study on the scalability of real-time performance of parallel network simulations, which is crucial for on-line simulations. Salient system characteristics of the subject military network scenarios are described for the benefit of exposure to the modeling and simulation research community. Our exercise not only highlights the relevance of parallel and distributed simulation techniques to an important real-life problem, but also demonstrates the feasibility of applying those techniques in a practical setting.
Distributed Network Simulations Using the Dynamic Simulation Backplane

(Georgia Institute of Technology, 2001-04) Riley, George F. ; Ammar, Mostafa H. ; Fujimoto, Richard M. ; Xu, Donghua ; Perumalla, Kalyan S.

Presents an approach for creating distributed, component-based simulations of communication networks by interconnecting models of sub-networks drawn from different network simulation packages. This approach supports the rapid construction of simulations for large networks by reusing existing models and software, and fast execution using parallel discrete event simulation techniques. A dynamic simulation backplane is proposed that provides a common format and protocol for message exchange, and services for transmitting data and synchronizing heterogeneous network simulation engines. In order to achieve plug-and-play interoperability, the backplane uses existing network communication standards and dynamically negotiates among the participant simulators to define a minimal subset of required information that each simulator must supply, as well as other optional information. The backplane then automatically creates a message format that can be understood by all participating simulators and dynamically creates the content of each message by using callbacks to the simulation engines. We describe our approach to interoperability as well as an implementation of the backplane. We present results that demonstrate the proper operation of the backplane by distributing a network simulation between two different simulation packages, ns2 and GloMoSim. Performance results show that the overhead for the creation of the dynamic messages is minimal. Although this work is specific to network simulations, we believe our methodology and approach can be used to achieve interoperability in other distributed computing applications as well.
Source-code Transformations for Efficient Reversibility

(Georgia Institute of Technology, 1999) Perumalla, Kalyan S. ; Fujimoto, Richard M.

An approach based on source-to-source compilation is presented for efficiently realizing reversibility of programs, in the context of the C language. The implementation of this approach in a portable "reverse C compiler" called rcc is described. The compiler takes arbitrary C functions as input, and renders them reversible, and, in addition, automatically generates their reverse functions. The system is sufficiently general to correctly handle complex data types and to handle complex control flow such as recursion and inter-mixing jump instructions. The compiler is designed to be general-purpose, to be used in any application requiring efficient reverse execution capability. A simple macro interface is used to help retarget the compiler to different application domains. As a case study, the application of rcc to optimistic parallel simulation is presented. Optimizations, such as "message-send slicing", are presented that help in reducing the overheads that may be added for achieving reversibility.
MetaTeD --- A Meta Language for Modeling Telecommunication Networks

(Georgia Institute of Technology, 1996) Perumalla, Kalyan S. ; Fujimoto, Richard M. ; Ogielski, Andrew T.

TeD is a language designed mainly for modeling telecommunication networks. The TeD language specification is separated into two parts -- (1) a "meta" language (2) an "external" language. The meta language specification is concerned with the high-level description of the structural and behavioral interfaces of various network elements. The external language specification is concerned with the detailed low-level description of the implementation of the structure and behavior of the network elements. The meta language, called MetaTeD, is described in this document (An external language specification, with C++ as the external language, is described in a separate related document.).
GTW++ -- An Object-oriented Interface in C++ to the Georgia Tech Time Warp System

(Georgia Institute of Technology, 1996) Perumalla, Kalyan S. ; Fujimoto, Richard M.

This document describes GTW++, an efficient object-oriented interface to the Georgia Tech Time Warp (GTW) parallel simulation system for shared memory multiprocessors. The interface, which is in C++, provides a clean and extensible set of abstractions for model developers wishing to use Time Warp as the parallel simulation paradigm. This interface delivers virtually the same performance as that of the C language interface to GTW. The object-oriented approach facilitates easily building higher-level interfaces, such as process-oriented views, over the basic GTW++ interface. GTW++ has been carefully designed so that almost identical interfaces can be supported for different parallel computing platforms, such as shared-memory machines and network of workstations, with appropriate underlying implementations for each platform. Furthermore, the GTW++ interface can be directly provided by the GTW kernel if and when the kernel itself is redesigned using an object-oriented approach.
A C++ Instance of TeD

(Georgia Institute of Technology, 1996) Perumalla, Kalyan S. ; Fujimoto, Richard M.

TeD is a language designed mainly for modeling telecommunication networks. The TeD language specification is separated into two parts --- (1) a "meta" language (2) an "external" language. The meta language specification is concerned with the high--level description of the structural and behavioral interfaces of various network elements. The external language specification is concerned with the detailed low-level description of the implementation of the structure and behavior of the network elements. The meta language, called MetaTeD, is described in a separate related document. An external language specification, with C++ as the external language, is described in this document. A software support system for the development and parallel simulation of TeD models is also described.