A network-based communication platform for a cognitive computer

Street is a reconfigurable parallel computer architecture. It executes a production language directly in hardware with the aim of realising advanced cognitive agents in a more energy efficient manner than conventional computers. Street requires frequent communication between many processing elements and to make this communication more energy efficient, a network-based communication platform, StreetNet, is proposed in this paper. It maps the processing elements onto a 2D mesh architecture optimized according to the data dependencies between them. A deadlock-free deterministic routing function is considered for this platform along with the concept of sleep period, analogous to human sleeping, to reorganize the placements of processing elements based on runtime traffic statistics. These mechanisms serve to reduce total network traffic and hence minimise energy consumption.Mostafa W. Numan, Jesse Frost, Braden J. Phillips, and Michael Liebel

A general analytical model of adaptive wormhole routing in k-ary n-cubes

Several analytical models of fully adaptive routing have recently been proposed for k-ary n-cubes and hypercube networks under the uniform traffic pattern. Although,hypercube is a special case of k-ary n-cubes topology, the modeling approach for hypercube is more accurate than karyn-cubes due to its simpler structure. This paper proposes a general analytical model to predict message latency in wormhole-routed k-ary n-cubes with fully adaptive routing that uses a similar modeling approach to hypercube. The analysis focuses Duato's fully adaptive routing algorithm [12], which is widely accepted as the most general algorithm for achieving adaptivity in wormhole-routed networks while allowing for an efficient router implementation. The proposed model is general enough that it can be used for hypercube and other fully adaptive routing algorithms

Software-based fault-tolerant routing algorithm in multidimensional networks

Massively parallel computing systems are being built with hundreds or thousands of components such as nodes, links, memories, and connectors. The failure of a component in such systems will not only reduce the computational power but also alter the network's topology. The software-based fault-tolerant routing algorithm is a popular routing to achieve fault-tolerance capability in networks. This algorithm is initially proposed only for two dimensional networks (Suh et al., 2000). Since, higher dimensional networks have been widely employed in many contemporary massively parallel systems; this paper proposes an approach to extend this routing scheme to these indispensable higher dimensional networks. Deadlock and livelock freedom and the performance of presented algorithm, have been investigated for networks with different dimensionality and various fault regions. Furthermore, performance results have been presented through simulation experiments

Parallel discrete event simulation: A shared memory approach

With traditional event list techniques, evaluating a detailed discrete event simulation model can often require hours or even days of computation time. Parallel simulation mimics the interacting servers and queues of a real system by assigning each simulated entity to a processor. By eliminating the event list and maintaining only sufficient synchronization to insure causality, parallel simulation can potentially provide speedups that are linear in the number of processors. A set of shared memory experiments is presented using the Chandy-Misra distributed simulation algorithm to simulate networks of queues. Parameters include queueing network topology and routing probabilities, number of processors, and assignment of network nodes to processors. These experiments show that Chandy-Misra distributed simulation is a questionable alternative to sequential simulation of most queueing network models

Safe and Verifiable Design of Concurrent Java Programs

The design of concurrent programs has a reputation for being difficult, and thus potentially dangerous in safetycritical real-time and embedded systems. The recent appearance of Java, whilst cleaning up many insecure aspects of OO programming endemic in C++, suffers from a deceptively simple threads model that is an insecure variant of ideas that are over 25 years old [1]. Consequently, we cannot directly exploit a range of new CASE tools -- based upon modern developments in parallel computing theory -- that can verify and check the design of concurrent systems for a variety of dangers\ud such as deadlock and livelock that otherwise plague us during testing and maintenance and, more seriously, cause catastrophic failure in service. \ud Our approach uses recently developed Java class\ud libraries based on Hoare's Communicating Sequential Processes (CSP); the use of CSP greatly simplifies the design of concurrent systems and, in many cases, a parallel approach often significantly simplifies systems originally approached sequentially. New CSP CASE tools permit designs to be verified against formal specifications\ud and checked for deadlock and livelock. Below we introduce CSP and its implementation in Java and develop a small concurrent application. The formal CSP description of the application is provided, as well as that of an equivalent sequential version. FDR is used to verify the correctness of both implementations, their\ud equivalence, and their freedom from deadlock and livelock

Cluster-Based Load Balancing Algorithms for Grids

E-science applications may require huge amounts of data and high processing power where grid infrastructures are very suitable for meeting these requirements. The load distribution in a grid may vary leading to the bottlenecks and overloaded sites. We describe a hierarchical dynamic load balancing protocol for Grids. The Grid consists of clusters and each cluster is represented by a coordinator. Each coordinator first attempts to balance the load in its cluster and if this fails, communicates with the other coordinators to perform transfer or reception of load. This process is repeated periodically. We analyze the correctness, performance and scalability of the proposed protocol and show from the simulation results that our algorithm balances the load by decreasing the number of high loaded nodes in a grid environment.Comment: 17 pages, 11 figures; International Journal of Computer Networks, volume3, number 5, 201