Evaluation of Optimized Barrier Algorithms for SCI Networks with Different MPI Implementations

The SCI Collectives Library is a new software package which implements optimized collective communication operations on SCI networks. It is designed to be coupled to different higher-level communication libraries (especially MPI implementations) by adapter modules, thereby giving them access to these optimized collectives. In this work, we present the design of the SCI Collectives Library and of adapter modules for Open MPI and NMPI. We also describe various barrier algorithms which we have implemented for this library and compare their performance to one another and to the barrier performance of MPI implementations which include support for SCI. 1

Implementationand Analysis of NonblockingCollectiveOperationson SCI Networks

1.1. Nonblocking Collective Communication Nonblocking collective communication operations are currently being considered for inclusion into the MPI standard and are an area of active research. The benefitsof such operations are documented by several recent publications, but so far, research concentrates on InfiniBand clusters. This paper describes an implementation of nonblocking collectives for clusters with the Scalable Coherent Interface (SCI) interconnect. We use synthetic and application kernel benchmarks to show that with nonblocking functions for collectivecommunicationperformanceenhancementscanbe achieved on SCI systems. Our results indicate that for the implementation of these nonblocking collectives data transfer methods other than those usually used for the blocking version should be considered to realize such improvements. 1

UNICORE-based Grid with MetaMPICH and MetaScheduling

Project no. FP6-004265 Reliable Orchestration of distributed MPI-Applications in