One-Sided Communication in Coarray Fortran: Performance Tests on TH-1A

One-sided communication mechanism of Messaging Passing Interface (MPI) has been extended by remote memory access (RMA) from several aspects, including interface, language and compiler, etc. Coarray Fortran (CAF), as an emerging syntactic extension of Fortran to satisfy one-sided communication, has been freely supported by the open-source and widely used GNU Fortran compiler, which relies on MPI-3 as the transport layer. In this paper, we present the potential of RMA to benefit the communication patterns in Cannon algorithm. EVENTS, a safer implementation of atomics to synchronize different processes in CAF, are also introduced via classic Fast Fourier Transform (FFT). In addition, we also studied the performance of one-sided communication based on different compilers. In our tests, one-sided communication outperforms two-sided communication only when the data size is large enough (in particular, inter-node transfer). CAF is slightly faster than the simple one-sided routines without optimization by compiler in MPI-3. EVENTS are capable of improving the performance of parallel applications by avoiding the idle time.