Parallel Timed Petri Nets Simulator

• Main Authors: Yuh-Der Lin, 林育德
• Other Authors: Dr.Chien-Chun Chou
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/19679176843138246348

碩士 === 淡江大學 === 資訊工程研究所 === 83 === Petri Nets（PN）是一種以正規方法（formal method）來描述和分析系 統行為的工具，特別是針對具有同時性（concurrent）與非同步特性 asynchronous）的系統。將時間引入Petri Nets之中（即所謂的Timed Petri Nets），則更能有效地對所描述的系統做作效能評估（ performance evaluation），例如Timed Petri Nets已被廣泛地應用在對 分散式系統（ distributed system）的效能分析上。隨著所描述系統之 複雜度（complexity）不斷地擴增，Petri Nets的網路結構（net structure）也變得更為複雜，以analytical的方式對Petri Nets作分析 則因記憶體（memory）與複雜度要求過高而變得不可行，而傳統上採用離 散事件模擬（discrete-event simulation）方式的循序Timed Petri Nets模擬器（sequential Timed Petri Nets simulator）也不能滿足我 們對執行時間上嚴格的要求，因此我們希望能將模擬器平行化（ parallelize），即將同一時間內所能處理的event個數增加，使模擬器在 多處理器（multiprocessor）之架構下能達到加速（speedup）的效果。 傳統上在討論離散事件模擬平行化時有兩種方法廣被使用：時間分區間法 （temporal decomposition method）與空間分區域法（spatial decomposition method)，這兩種方法各有其優點，我們的平行Timed Petri Nets模擬器將採用空間分區域法中的distributed simulation mechanism來做模擬，同時我們將對平行化時所遭遇的問題，如切割 partition）、訊息傳遞（message passing）、模擬結果收集 ]simulation results collection）等尋求解決之道。最後我們將在 Transputer之多處理器上實作一個平行Timed Petri Nets 模擬器。 Timed Petri Nets is a modeling tool that can be used to describe and analyze the behaviors of a system with characteristics such as concurrencyand asynchronism. Because the complexity and size of a Timed Petri Netsmodel for a physical system are steadily increasing, to analyze a very complex net model by using existing analytical methods has become impossible. Alternatively, a discrete-event Timed Petri Nets simulator can be used to obtain approximated net solutions. The only main drawback is the longsimulation run time. In order to reduce the simulation run time, severalmethods have emerged to construct a parallel simulator counterpart. There are two methodologies often used in parallel discrete-event simulation, that is, the temporal decomposition method and the spatial decomposition method. We use one of the spatial decomposition methods, the distributed simulation mechanism, in constructing our parallel Timed Petri Nets simulator.Problems such as partitioning, messages passing, and collecting of simulationresults have also been solved. Finally we have implemented a parallel Timed Petri Nets simulator on a Transputer network. More study on performance evaluation of our simulators will be conducted.