Design and Implementation of a One-Sided Communication Interface for the IBM eServer Blue Gene

This paper discusses the design and implementation of a one- sided communication interface for the IBM Blue Gene/L supercomputer. This interface facilitates ARMCI and the Global Arrays toolkit and can be used by other one-sided communication libraries. New protocols, interrupt driven communication, and compute node kernel enhancements were required to enable these libraries. Three possible meth- ods for enabling ARMCI on the Blue Gene/L software stack are discussed. A detailed look into the development process shows how the implementation of the one-sided communi- cation interface was completed. This was accomplished on a compressed time scale with the collaboration of various or- ganizations within IBM and open source communities. In addition to enabling the one-sided libraries, bandwidth en- hancements were made for communication along a diagonal on the Blue Gene/L torus network. The maximum bandwidth improved by a factor of three. This work will enable a variety of one-sided applications to run on Blue Gene/L.