A Conservative Parallel Simulation Algorithm for Entity-Oriented Modeling

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. Examples of conservative protocols include the asynchronous ChandyMisra -Bryant (CMB) algorithm [2], and synchronous algorithms such as that described in [1,6]. In all these protocols, time-guarantee (or time-bound) information for an LP is computed from the other LP's (e.g. in CMB protocol, an LP i sends lookahead information to a next LP j , to give a lower time-bound for future events arriving at LP j from LP i .) In this paper, we propose a variant form of conservative parallel simulation protocol in which the timeguarantee for an LP is computed from the existing events in the system. The difference is this: in an algorithm such as the CMB protocol, an LP i may process different types of events, each of which may generate different events that proceed on to different LP's. It can be dif..

Building a Conservative Parallel Simulation with Existing Component Libraries

. Our application is a parallel discrete event simulation of a wafer fabrication plant. When implementing such an application using a conservative protocol [2] on a shared-memory multiprocessor, an effective approach is for the programmer to use a general parallel runtime library, and implement optimizations specific to the simulation application. We initially evaluated four runtime libraries [7] and found Active Threads [11] to be most suitable and efficient for thread-creation and synchronization. But Active Threads' memory management does not scale well. We therefore added a different memory management library called Vmalloc [10] to provide a more efficient way to dynamically allocate and deallocate objects. For parallel application development, it is good news that there are public-domain research libraries which are both efficient and stable enough to build applications on shared-memory multiprocessor. The ability to use independent component libraries cannot be over-emphasized, a..

A Parallelism Analyzer Algorithm for a Conservative Super-Step Simulation Protocol

Given an existing complex sequential simulation program, it is useful to have a parallelism analysis algorithm to quickly predict the corresponding parallel simulation program's performance. Wong et al. [12] have described such an algorithm for the asynchronous Chandy-Misra-Bryant simulation protocol. This paper describes a parallelism analysis algorithm for a synchronous "super-step" protocol [8] which we evolved from [7, 2]. We also discuss the assumptions needed in order for the prediction to be meaningful (i.e it should reflect at least one of the possible parallel runs), and the analyzer algorithm's correctness. Finally we will briefly discuss the algorithm modifications needed if we are to remove one of the assumptions. 1 Introduction The work in this paper is from an ongoing project to study how parallel simulation techniques can be applied in a virtual factory simulation [6]. A virtual factory model includes manufacturing, business processes and communications network, to all..

Criticality Of Detailed Modeling In Semiconductor Supply Chain Simulation

Supply chain management offers a large potential for organizations to reduce costs and improve customer service performance. Simulation of supply chains can help in these objectives by evaluating the impact of alternate inventory control policies. Supply chain simulation involves modeling of multiple factories across the chain and can get quite complex. Analysts typically carry out such simulation at a coarse level of detail to keep the complexity and computing resources manageable. However, modeling at coarse levels may reduce the accuracy of outputs and affect the quality of decisions. In this paper, we report on a study to compare the quality of results at different levels of details in a semiconductor supply chain simulation. 1 INTRODUCTION The globalization of markets is forcing the producers to look for ways to improve their competitive positions through focusing on supply chain management. Supply chain management involves planning and managing the flow of material and informatio..

Implementation Lessons of Performance Prediction Tool for Parallel Conservative Simulation

. Performance prediction is useful in helping parallel programmers answer questions such as speedup scalability. Performance prediction for parallel simulation requires rst working out the performance analyzer algorithms for specic simulation protocols. In order for the prediction results to be close to the results from actual parallel executions, there are further considerations when implementing the analyzer. These include (a) equivalence of code between the sequential program and parallel program, and (b) system eects (e.g. cache miss rates and synchronization overheads in an actual parallel execution). This paper describes our investigations into these issues on a performance analyzer for a conservative, \super-step" (synchronous) simulation protocol. 1 Introduction Parallel programmers often use performance predictions to better understand the behavior of their applications. In this paper, we discuss the main implementation issues to consider in order to obtain accu..