Distributed Simulation Protocols Research Articles

Distributed simulation performance data mining

The performance of logical process based distributed simulation (DS) protocols like Time Warp and Chandy/Misra/Bryant is influenced by a variety of factors such as the event structure underlying the simulation model, the partitioning into submodels, the performance characteristics of the execution platform, the implementation of the simulation engine and optimizations related to the protocols. The mutual performance effects of parameters exhibit a prohibitively complex degree of interweaving, giving analytical performance investigations only relative relevance. Nevertheless, performance analysis is of utmost practical interest for the simulationist who wants to decide on the suitability of a certain DS protocol for a specific simulation model before substantial efforts are invested in developing sophisticated DS codes. Since DS performance prediction based on analytical models appears doubtful with respect to adequacy and accuracy, this work presents a prediction method based on the simulated execution of skeletal implementations of DS protocols. Performance data mining methods based on statistical analysis and a simulation tool for DS protocols have been developed for DS performance prediction, supporting the simulationist in three types of decision problems: (i) given a simulation problem and parallel execution platform, which DS protocol promises best performance, (ii) given a simulation model and a DS strategy, which execution platform is appropriate from the performance viewpoint, and (iii) what class of simulation models is best executed on a given multiprocessor using a certain DS protocol. Methodologically, skeletons of the most important variations of DS protocols are developed and executed in the N-MAP performance prediction environment. As a mining technique, performance data is collected and analyzed based on a full factorial design. The design predictor variables are used to explain DS performance.

Performance comparison of high-level algebraic nets distributed simulation protocols

Abstract We address the problem of developing distributed simulation techniques to analyze Extended Concurrent Algebraic Term Nets (ECATNets). ECATNets ire a kind of High-Level Algebraic Nets used for specifying various aspects of distributed and parallel systems. The conservative and optimistic approaches of Distributed Discrete Event Simulation (DDES) are used as the starting point to develop a simulation framework for studying their behaviour. The ECATNet model to be simulated is partitioned into several connected subnets simulated in parallel by several Logical Processes (LPs).

Optimistic distributed simulation based on transitive dependency tracking

In traditional optimistic distributed simulation protocols, a logical process (LP) receiving a straggler rolls back and sends out anti-messages. The receiver of an anti-message may also roll back and send out more anti-messages. So a single straggler may result in a large number of anti-messages and multiple rollbacks of some LPs. In the authors' protocol, an LP receiving a straggler broadcasts its rollback. On receiving this announcement, other LPs may roll back but they do not announce their rollbacks. So each LP rolls back at most once in response to each straggler. Anti-messages are not used. This eliminates the need for output queues and results in simple memory management. It also eliminates the problem of cascading rollbacks and echoing, and results in faster simulation. All this is achieved by a scheme for maintaining transitive dependency information. The cost incurred includes the tagging of each message with extra dependency information and the increased processing time upon receiving a message. They also present the similarities between the two areas of distributed simulation and distributed recovery. They show how the solutions for one area can be applied to the other area.

Distributed simulation with locality

We describe MOSS, a small language of mobile distributed objects and system-wide references, uncommitted to any distributed simulation protocol, but which can be executed as a distributed conservative simulation with automatic deduction of lookahead. We show how the MOSS programmer can control the dynamic distribution and locality of simulation objects by simple means which provide natural modelling functions. Preliminary results show how programmed locality can reduce communication costs in simulation.