Abstract not found

Multicast communication services, in which the same message is delivered from a source node to an arbitrary number of destination nodes, are being provided in new generation multicomputers. Broadcast is a special case of multicast in which a message is delivered to all nodes in the network. The nCUBE-2, a wormhole-routed hypercube multicomputer, provides hardware support for broadcast and a restricted form of multicast in which the destinations form a subcube. However, the broadcast routing algorithm adopted in the nCUBE-2 is not deadlock-free. In this paper, four multicast wormhole routing strategies for two-dimensional (2D) mesh multicomputers are proposed and studied. All of the algorithms are shown to be deadlock-free. These are the first deadlock-free multicast wormhole routing algorithms ever proposed. A simulation study has been conducted that compares the performance of these multicast algorithms under dynamic network traffic conditions in a 2D mesh. The results ind...

Massively parallel computers (MPC) are characterized by the distribution of memory among an ensemble of nodes. Since memory is physically distributed, MPC nodes communicate by sending data through a network. In order to program an MPC, the user may directly invoke low-level message passing primitives, may use a higher-level communications library, or may write the program in a data parallel language and rely on the compiler to translate language constructs into communication operations. Whichever method is used, the performance of communication operations directly affects the total computation time of the parallel application. Communication operations may be either point-to-point, which involves a single source and a single destination, or collective, in which more than two processes participate. This paper discusses the design of collective communication operations for current systems that use the wormhole routing switching strategy, in which messages are divided into small pieces and...

This paper proposes a novel concept of multidestination worm mechanism which allows a message to be propagated in a wormhole network conforming to the underlying base routing scheme (ecube, planar, turn, or fully adaptive). Using this model, any source has potential to deliver a message to multiple destinations in any valid path in the system conforming to the base routing scheme while encountering only a single communication start-up. The flexibility of sending unicast messages exists under this model as a subset operation. Two schemes are developed and evaluated under this model to perform fast multicasting on 2D/3D meshes/tori. Not only do these schemes demonstrate superiority over Umesh (unicast-based multicast) [25] and Hamiltonian-Path-based [24] schemes, they indicate a very unique and interesting result that the cost of multicast operations can be reduced or kept near-constant in e-cube systems as the degree of multicast (number of destinations/src) increases. The proposed sc...

Abstract not found

banikaze,moorthy,panda¢

This paper addresses efficient implementation of barrier synchronization in wormhole-routed hypercube multicomputers. For those systems supporting only unicast communication in hardware, a novel software tree approach, the U-cube tree, is proposed. An important feature of the U-cube tree is that all messages injected into the network are guaranteed to be contention-free. Performance measurements of several barrier synchronization techniques implemented on a 64-node nCUBE-2 are given.

Abstract not found

This paper presents efficient multicasting with reduced contention on irregular networks with switchbased wormhole interconnection and unicast message passing. First, it is proved that for an arbitrary irregular network with a typical deadlock-free, adaptive routing, it may not be possible to create an ordered list of nodes to implement an arbitrary multicast in a contention-free manner with minimal number of communication steps. Next, three different multicast algorithms are proposed with their respective node orderings to reduce contention: switchbased ordering (SO), switch-based hierarchical ordering (SHO), and chain concatenation ordering (CCO). A variation of a binomial tree-based communication pattern with unicast message passing is used on the above ordered lists to implement multicast. The proposed multicast algorithms are compared with each other as well as with the naive random ordering (RO) algorithm for a range of system sizes, switch sizes, message lengths, degrees of co...

. Efficient implementation of multicast communication is critical to the performance of message-based scalable parallel computers and switch-based high speed networks. This paper deals with address issues occurring in the message header for the transmission of multicast messages. Multi-address encoding is becoming critical to system performance as the scale of networks is getting larger and the demand of multicast communication is getting higher. Several multi-address encoding schemes are investigated and explored. Although the proposed multi-address encoding schemes can be applied to networks with different switching techniques, the emphasis of this paper is on the emerging wormhole routing technique. 1 Introduction Multicast communication, which refers to the delivery of a message from a single source node to a number of destination nodes, is a frequently used communication pattern in distributed-memory parallel computers and computer networks. Efficient implementation of multicast ...