Efficient Approaches to Mitigate Communication Bottlenecks in MPI Communicator Splitting by Type

MPI_Comm_split_type is a widely utilized operation in Message Passing Interface (MPI) programs, efficiently categorizing processes into two levels: inter-node and intra-node spaces. This division enhances the organization and management of communication, thereby reducing unnecessary communication overhead. Nevertheless, conventional implementation approaches suffer from two main deficiencies. Firstly, during node information collection, the hierarchy of processes remains indeterminate, resulting in significant redundant inter-node data transmission overhead. Secondly, the one-to-many communication pattern easily leads to communication bottlenecks, significantly increasing latency.To address these limitations, this paper introduces two optimization techniques aimed at minimizing the substantial redundancy in inter-node data transmission overhead. We integrate these techniques as dynamic libraries and evaluate them across two multi-core clusters, scaling experiments up to 512 computing nodes. Experimental results demonstrate that compared to state-of-the-art collective implementations, our optimization approach offers performance improvements ranging from 1.4 to 9.6 times. Importantly, these techniques exhibit outstanding scalability, maintaining exceptional performance in large-scale scenarios.