16310485
Stably Computable Properties of Network Graphs
We consider a scenario in which anonymous, finite-state sensing devices are deployed in an ad-hoc communication network of arbitrary size and unknown topology, and explore what properties of the network graph can be stably computed by the devices. We show that they can detect whether the network has degree bounded by a constant d, and, if so, organize a computation that achieves asymptotically optimal linear memory use. We define a model of stabilizing inputs to such devices and show that a large class of predicates of the multiset of final input values are stably computable in any weakly-connected network. We also show that nondeterminism in the transition function does not increase the class of stably computable predicates.
22543009
Self-stabilizing Population Protocols
Self-stabilization in a model of anonymous, asynchronous interacting agents deployed in a network of unknown size is considered. Dijkstra-style round-robin token circulation can be done deterministically with constant space per node in this model. Constant-space protocols are given for leader election in rings, local-addressing in degree-bounded graphs, and establishing consistent global direction in an undirected ring. A protocol to construct a spanning tree in regular graphs using O(logD) memory is also given, where D is the diameter of the graph. A general method for eliminating nondeterministic transitions from the self-stabilizing implementation of a large family of behaviors is used to simplify the constructions, and general conditions under which protocol composition preserves behavior are used in proving their correctness.
21605308
Impact of priority-based ATM switch design on system performance
We investigate the performance impact of a Banyan type MIN ATM switch with priority-based design and its impact on system performance. The switch design consists of static buffer splitting, adaptive buffer splitting, as well as the priority-based selection strategies for solving cell contentions. A new analytical model is developed for the favorite load traffic pattern which can reflect some typical ATM applications and also include the uniform load as its special case. System performance comparisons are conducted for a number of different priority-based ATM switch designs.<<ETX>>
22852167
Parallel Random Tunneling Algorithm for Structural Optimization of Lennard-Jones Clusters up to N = 330
A random tunneling algorithm (RTA) is derived from the terminal repeller unconstrained subenergy tunneling (TRUST) algorithm, and the parallelization of the RTA is implemented with an island parallel paradigm. Combined with the techniques of angular moving, the parallel random tunneling algorithm (PRTA) is applied to the optimization of Lennard-Jones (LJ) atomic clusters, and all the global minima of LJ clusters with size up to 200 are successfully located. For the optimization of larger cluster, a PRTA with an improved seeding technique is developed and successfully applied to the optimization of LJ151-LJ309. Furthermore, the optimized structures of LJ309-330 with the PRTA, which have not been studied before, are also provided.
16613474
Extensible communication architecture for grid nodes
Nodes in the grid can be connected through a multigigabit network. However, the network interfaces in the nodes can become a bottleneck for the maximum achievable bandwidth among nodes. We propose an extensible communication architecture to avoid the limitations of the network interfaces by integrating multiple network interfaces in each node. The proposed solution deploys a technique to balance the network traffic load among multiple network interfaces in a single node. While this technique enhances communication bandwidth among the nodes, it is distributed and does not require any coordination or reservation mechanisms. It achieves the maximum possible bandwidth between any pair of grid nodes with multiple network interfaces. The experimental evaluation provided good results and demonstrated the benefits of the proposed architecture.
2360073
Performance properties of combined heterogeneous networks
We study the performance properties of combined multiple heterogeneous networks. We consider two nodes: node1 and node2, with multiple heterogeneous physical networks connecting them. Each network has some properties such as bandwidth, latency, and packet loss ratio. We develop an analytical model to find the peak performance, or upper bound, of combined networks for the transfer of a message of a given size in parallel. The model is based on the existence of an optimal load balancing mechanism for parallel transfer that fully utilizes the existing networks. The paper provides a framework to find the peak performance parameters of message transfer over combined heterogenous networks as well as to measure the actual utilization and efficiency of parallel message transfer implementations.
179733
Exploiting redundancy to boost performance in a RAID-10 style cluster-based file system
While aggregating the throughput of existing disks on cluster nodes is a cost-effective approach to alleviate the I/O bottleneck in cluster computing, this approach suffers from potential performance degradations due to contentions for shared resources on the same node between storage data processing and user task computation. This paper proposes to judiciously utilize the storage redundancy in the form of mirroring existed in a RAID-10 style file system to alleviate this performance degradation. More specifically, a heuristic scheduling algorithm is developed, motivated from the observations of a simple cluster configuration, to spatially schedule write operations on the nodes with less load among each mirroring pair. The duplication of modified data to the mirroring nodes is performed asynchronously in the background. The read performance is improved by two techniques: doubling the degree of parallelism and hot-spot skipping. A synthetic benchmark is used to evaluate these algorithms in a real cluster environment and the proposed algorithms are shown to be very effective in performance enhancement.