Memory Efficient One-Sided Communucation Library "ACP" in Globary Memory on Raspberry Pi 2

Previously, communications in parallel programs for High Performance Computing (HPC) and Distributed Computing (DC) are mostly written with two-sided communication interfaces that are based on a pair of operations, Send and Receive. Since such interface requires explicit synchronization between both sides of the communication, techniques for communication optimization such as overlapping are not efficiently described in many cases. On the other hand, one-sided communication interface is becoming important as a method to describe asynchronous communications to enable highly overlapped communication with computation. As one of such interface, in this demonstration, Advanced Communication Primitives (ACP) is introduced. ACP is a portable interface that supports UDP, IBverbs of InfiniBand and Tofu library of K Computer. In addition to that, it is designed to be memory efficient. For example, with 10 thousand processes, the memory consumption of ACP over UDP is estimated to be less than 1MB. Since the number of computational elements is increasing more rapidly than the amount of available memory, this memory efficiency is becoming one of the keys for parallel programs in HPC and DC. To show this characteristics, we run ACP library on Raspberry Pi 2, and examine its performance and memory consumption.