Modelling and simulation of interconnection networks: a conservative parallel approach

A new and efficient technique is presented for modelling and simulation of interconnect networks which include multiconductor microstrip transmission lines (MMTL) with inhomogeneous cylindrical substrates. The potential and field distributions in the cross section of the MMTL are calculated by solving a set of series equations using Galerkin's method. The charge distribution on the conductors, maxwellian capacitance matrix per unit length, and the modal characteristic impedances of the MMTL are determined. Results obtained have been compared for various types of microstrip lines with those obtained in the literature; good agreement has been found.

This paper presents a parallel algorithm for the simulation of large complex interconnect networks with frequency-dependent parameters. The equivalent transmission line model, which is suitable for time-domain simulation, is introduced for the modeling of dispersive interconnects. By means of the equivalent multi-port model, the interconnects are separated from other circuit elements, and thus makes the parallel simulation feasible. Based on the proposed technique, a program named FdSPICE is developed for parallel simulation of large interconnect networks. The accuracy and efficiency of FdSPICE are demonstrated by numerical examples.

This paper describes the design and use of the interconnection network simulator (ICNS) framework. ICNS is a modular, object-oriented simulation system that has been developed to investigate performance issues in multiprocessor interconnection networks that exploit photonic technology in their design. We describe the ICNS infrastructure, present two distinct photonic interconnection networks that have been modeled using ICNS, and give performance results for each of these networks.

Null message algorithm (NMA) is one of the efficient conservative time management algorithms that use null messages to provide synchronization between the logical processes (LPs) in a parallel discrete event simulation (PDES) system. However, the performance of a PDES system could be severely degraded if a large number of null messages need to be generated by LPs to avoid deadlock. In this paper, we present a mathematical model based on the quantitative criteria specified in (Rizvi et al., 2006) to optimize the performance of NMA by reducing the null message traffic. Moreover, the proposed mathematical model can be used to approximate the optimal values of some critical parameters such as frequency of transmission, Lookahead (L) values, and the variance of null message elimination. In addition, the performance analysis of the proposed mathematical model incorporates both uniform and non-uniform distribution of L values across multiple output lines of an LP. Our simulation and numerical analysis suggest that an optimal NMA offers better scalability in PDES system if it is used with the proper selection of critical parameters.

Graph embedding has been known as a powerful tool for implementation of parallel algorithms and simulation of interconnection networks. In this paper, we introduce a technique to obtain a lower bound for the dilation of an embedding. Moreover, we give algorithms for embedding variants of hypercubes with dilation 2 proving that the lower bound obtained is sharp. Further, we compute the exact wirelength of embedding folded hypercubes and augmented cubes into hypercubes.

Fine-Grained Parallel and Distributed Spatial Stochastic Simulation of Biological Reactions

In this paper we show the difficulties encountered when performing full system simulation of a distributed memory parallel system. To illustrate the problem, we have chosen a workbench that evaluates the impact on application performance of some simple congestion-control mechanism that can be implemented in the interconnection network. Applications of choice are some of those included in the NAS parallel benchmarks. Running a full-system, execution-driven simulation that combines Simics with an interconnection network simulator, we observe some unexpected, negative interactions of overlapping congestion control techniques implemented at the network level and at the host level. Each MPI implementation uses a different protocol stack, and some of them work without TCP. We compare and contrast results obtained with MPICH, LA-MPI and LAM

The implementation of parallel algorithms and the simulation of interconnection networks can be modeled into a graph embedding problem. Several cost parameters are used to assess the quality of an embedding. The wirelength is one of these factors that is frequently taken into account. A fractal cubic network is a new variant of the hypercube graph. In this study, we compute the wirelength of an embedding of the hypercube [Formula: see text] into the fractal cubic network [Formula: see text] using [Formula: see text]-partition.

This paper considers software tools and linguistic constructions of the network simulator TRIADNS. Nowadays network applications - especially in the area of wireless networks - are becoming more and more complex which makes the design and the testing almost impossible without appropriate software. This software available to aid the user in simulating previously designed scenarios, scalable algorithms and changing structure of computer network. So it is necessary to have effective and flexible program tools for computer network design and simulation. Network simulator must design and investigate not only hardware, but software too, explore computer networks, considering in particular the specific characteristics of a variety of computer networks. Besides computer networks may include a lot of nodes. This paper discusses approaches allowing to decide the problems mentioned above: hierarchical model, using ontologies and Data Mining methods for the analyses of simulation results, using several computing nodes for computer network simulation (distributed and parallel simulation).

In this paper, the relationship between the computational models of object-oriented rewriting and parallel discrete-event simulation models is explored. A discrete-event simulation program in which several objects interact with each other by exchanging messages may have a high degree of concurrency (which can be exploited using optimistic or conservative parallel simulation methods). We report on some observations on using rewriting logic in the field of parallel discrete event simulations, and investigate how parallel simulation applications can be expressed using object-oriented rewriting.

Heterogeneous multicore processors have recently become de facto computing engines for state-of-the-art embedded applications. Nonetheless, very little research focuses on the scheduling of periodic (implicit-deadline) real-time tasks upon heterogeneous multicores under the requirements of task synchronization, which is stemmed from resource access conflicts and can greatly affect the schedulability of tasks. In view of partitioned Earliest Deadline First and Multiprocessor Stack Resource Policy, we first discuss the blocking-aware utilization bound for uniform heterogeneous multicores and then illustrate its non-monotonicity, where the bound may decrease with more deployed cores. Following the insights obtained from the bound analysis, taking the system heterogeneity into consideration, we propose a Synchronization-Aware Task Partitioning Algorithm for Heterogeneous Multicores (SA-TPA-HM)). Several resource-guided and heterogeneity-oriented mapping heuristics are incorporated to reduce the negative impacts of blocking interferences for better schedulability performance of tasks and balanced workload distribution across cores. The extensive simulation results show that SA-TPA-HM can obtain the schedulability ratios approximate to an Integer Non-Linear Programming--based solution, and much higher (e.g., 60% more) in contrast to the existing partitioning algorithms targeted at homogeneous multicores. The measurement results in Linux kernel further reveal the practical viability of SA-TPA-HM that can experience lower runtime overhead (e.g., 15% less) when compared to other mapping schemes.

Current airspace is sectorized according to some predefined rules that are not flexible. To facilitate utilizing the airspace more efficiently, methods to design sectors need to be promoted. In this paper, we propose an undirected graph cut-based approach that employs a memetic local search-embedded constrained evolution algorithm, NSGA-II, to generate nondominated airspace configurations. We also propose a new concave hull-based method to automatically depict sector boundaries. In addition, we also study the configuration transition problem. We define the similarity of the two different configurations and calculate their similarity with a bisection diagram and a minimum cost flow algorithm. We build a forward network to represent configuration transitions across several consecutive time periods and use multiobjective dynamic programming to determine a series of nondominated configuration links from the first period to the end. We test our approaches by simulation in high-altitude airspace controlled by Beijing Area Control Center. The results show that our sectorization method outperforms the current configuration in practice, providing a lower sector number, lower intersector flow, more balanced workload distribution among the different sectors, and no constraint violations, so that the proposed approach shows its significant potential as practical applications for dynamic airspace configuration.

The inherent computational complexity of validating and verifying concurrent systems implies a need to be able to exploit parallel and distributed computing architectures. We present a new distributed algorithm for state space exploration of concurrent systems on computing clusters. Our algorithm relies on Remote Direct Memory Access (RDMA) for low-latency transfer of states between computing elements, and on state reconstruction trees for compact representation of states on the computing elements themselves. For the distribution of states between computing elements, we propose a concept of state stealing. We have implemented our proposed algorithm using the OpenSHMEM API for RDMA and experimentally evaluated it on the Grid'500 testbed with a set of benchmark models. The experimental results show that our algorithm scales well with the number of available computing elements, and that our state stealing mechanism generally provides a balanced workload distribution.

In this paper a binary integer linear programming model is proposed for scheduling tour of service personnel in aftersale service process. The model aims to minimize the service personnel’s overall travel time of visiting all customers with additional side conditions that customers should be served by first come first serve (FCFS) priority basis within specified service response time. These side conditions are important strategies in present era of time-based competition. The objective and side conditions are considered for both profitability and effectiveness. Indeed, for given service response time, optimal tour plan would minimize the quantity of service personnel. This decreases the hiring cost of service personnel and thus increases the profitability of after-sale service process. On the other hand, for given quantity of service personnel, optimal tour plan would reduce the service response time. Responsive after-sale service on FCFS priority basis will increase the customer satisfaction, which in turn leads to more repeat orders and hence improves the profitability. The proposed model can capture all realistic constraints of service management process, such as time windows, skill requirement, balanced workload distribution, etc. A numerical illustration is included to demonstrate the effectiveness of the proposed model in conducting economic analysis of an after-sale service process.

An implementation of a conservative parallel simulator with deadlock avoidance is presented. Its performance when working with a realistic model of a message routing network is evaluated and contrasted against a sequential simulator. Different factors that improve the performance of the parallel simulation are discussed, focusing in the model under study and the available computer: a network of transputers. These factors are the load of the model being simulated, the grain size of the simulator and the simulator ability to exploit the lookahead property of the model. >