|Context Identifier Allocation in Open MPI
|Year of Publication
|Bosilca, G., T. Herault, and J. Dongarra
|Technical Report Series Title
|University of Tennessee Computer Science Technical Report
|Innovative Computing Laboratory, University of Tennessee
|The concept of communicators is a central notion in Message Passing Interface, allowing on one side the MPI implemen- tation to specialize it’s matching and deliver messages in the right context, and on the other side the library developers to contextualize their message exchanges, and scope different algorithms to well-defined groups of processes. More pre- cisely, all communication objects in MPI are derived from a communicator at some point. All MPI functions allowing the creation of new communicators have a collective mean- ing, either over the group of processes from the parent com- municator or those from the target communicator. Thus, the perfromance of the communicator creation is tied to the col- lective communication performance, as well as the amount of data needed to be exchanged in order to consistently create this new communicator. We introduce several communica- tor creation algorithms, and present their implementation in the context of Open MPI. We explore the performance of these new algorithms and compare them with state-of-the- art algorithms available in other MPI implementations.
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