| As the demands for high performance computation have changed and promoted,to increasing data scale becomes the more efficient way to achievements than to develop parallel algorithms. The heterogeneous multi-cluster distributed environment systems can provide more computing power and storage capacity. But the increasing physics level of parallel computing and the mixed programming models result in a more complex design of multi-level parallelization in programming.This paper analyzed MPICH2 parallel library,a popular message passing interface,for this problem and research the extension of MPI for the multi-level clusters according to the complexity and multiplicity of WAN as well as the characteristic of message passing. The essential content is the expansion of MPI which make it easy to complete data transmission in WAN and be completely compatible with the MPI standard. The research covers three aspects: The first is the extension of runtime environment which includes initialization , disposition ,monitoring,management and logging out on the clusters'nodes. And it manages the start and termination of parallel application as well as the monitoring,acquisition,analysis and feedback of kinds of system messages. It consists of agent node runtime environment and local node runtime environment. Next is to manage the processes. The task includes the management of processes group and communicators. Finally,in view of the characteristics of environment topology of WAN,the efficiency of message passing is enhanced by optimizing the functions based on MPICH2.In the synthesis,the extension of MPI provided a solution for establishing multi-level clusters in WAN. It has certain practical significance for applications which have demand of large-scale computing power and storage capacity. |
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