For small memory communications in the exascale computing, we are developing an Advanced Communication Primitives (ACP) library based on one-sided communication. ACP library uses Global Address (GA) data for identifying a logical address of a process. We estimated memory requirements of ACP library for four communication patterns of the OpenFMO application. The maximum memory requirement of GAs is about 1 MByte for the master process of master-worker communications. This result shows the memory requirement of GAs is considerably smaller than the available memory size of one process of exascale computer.
