Modeling Performance of Many-to-One Collective Communication Operations in Heterogeneous Clusters

This paper presents a performance model for Many-to-One type communications on a dedicated heterogeneous cluster of workstations based on a switched Ethernet network. This study finds that Many-to-One communication is more complex than One-to-Many and Point-to-Point communications as it does not show a linear or even continuous dependence of the execution time on message sizes. It displays a very high jump in execution time for a significant range of message sizes. As a result, the proposed model is divided into three parts. The first part is for small sized messages whose model is linear, the second part models the congestion region, and the last part is for large message sizes where linearity resumes. The proposed model is validated for accuracy by the experiments on various platforms with different MPI implementations