Preliminary Performance Evaluation of Coarray-based Implementation of Fiber Miniapp Suite using XcalableMP PGAS Language

XcalableMP (XMP) is a Partitioned Global Address Space (PGAS) language that is defined by the XMP Specification Working Group of the PC Cluster Consortium. This paper provides the implementation and evaluation of the Fiber miniapp suite, which is primarily maintained by RIKEN Advanced Institute for Computational Science, on the basis of the local-view parallelization model using the coarray feature of XMP. In many cases, a coarray-based implementation can be obtained by replacing original Message Passing Interface (MPI) functions with coarray assignment statements. Herein, we demonstrate a method to rewrite irregular applications into the coarray-based style. Evaluation on the K computer using the Omni XMP compiler we have been developing shows that some XMP implementations are comparable to their original implementations, but there is performance degradation found in the others, which is due to the large overhead from allocating dynamic coarrays at runtime.