Parallel Discrete Event Simulation Techniques Research Articles

Towards scalable network emulation

The Internet protocol traffic and network emulator (IP-TNE) enables real hosts and a real network to interact with a virtual network. It combines a real-time network simulator with a mechanism to capture packets from and write packets to a real network. Packets generated by external hosts interact with synthetic traffic within the virtual network, providing a controlled environment for testing real Internet applications. IP-TNE can also generate simulated traffic internally enabling its use as a sophisticated workload generator for stress testing real Web servers. This paper focuses on two issues related to the scalability of network emulators, such as IP-TNE. The scalability of the virtual network within the emulator and the scalability of the real-time I/O interface used to interoperate with the physical network. For the scalability of the virtual network, parallel discrete event simulation techniques are employed. The scalability of the real-time interfaces requires handling varying amounts of network I/O and mapping packets into the simulator efficiently.

Web server benchmarking using parallel WAN emulation

This paper discusses the use of a parallel discrete-event network emulator called the Internet Protocol Traffic and Network Emulator (IP-TNE) for Web server benchmarking. The experiments in this paper demonstrate the feasibility of high-performance WAN emulation using parallel discrete-event simulation techniques on shared-memory multiprocessors. Our experiments with the Apache Web server achieve 3400 HTTP transactions per second for simple Web workloads, and 1000 HTTP transactions per second for realistic Web workloads, for static document retrieval across emulated WAN topologies of up to 4096 concurrent Web/TCP clients. The results show that WAN characteristics, including round-trip delays, link speeds, packet losses, packet sizes, and bandwidth asymmetry, all have significant impacts on Web server performance. WAN emulation enables stress testing and benchmarking of Web server performance in ways that may not be possible in simple LAN test scenarios.

The Development of Conservative Superstep Protocols for Shared Memory Multiprocessor Systems

This paper summarizes our work involving the successive refinements of a conservative superstep protocol. The refined protocols are known as the SST, SLS, and FET protocols. Each of the refinements improves the safetime bound, which in turn reduces the number of supersteps. In general, this helps to reduce the synchronization overhead and thus the execution time. However, a change in the number of supersteps can also introduce load imbalances within supersteps into the simulation. This observation becomes apparent with the FET protocol in particular. The performance of the refined protocols is compared through several semiconductor supply-chain simulation models. The results from the experiments strongly indicate the feasibility of using parallel discrete-event simulation techniques in the simulation of large scale systems such as a supply-chain.

Maya: a simulation platform for distributed shared memories

Maya is a simulation platform for evaluating the performance of parallel programs on parallel architectures. It allows the rapid prototyping of memory protocols with varying degrees of coherence and facilitates the study of the impact of these protocols on application programs. The design of Maya and its simulation mechanism are discussed. Performance results on architectural simulation with different memory coherence protocols are presented. Parallel discrete event simulation techniques are adopted for the execution-driven simulation of parallel architectures.