Hiding latency in Coarray Fortran 2.0

Abstract

In Numrich and Reid's 1998 proposal [17], Coarray Fortran is a simple set of extensions to Fortran 95, principal among which is support for shared data known as coarrays. Responding to short-comings in the Fortran Standards Committee's addition of coarrays to the Fortran 2008 standards, we at Rice envisioned an extensive update which has come to be known as Coarray Fortran 2.0 [15]. In this paper, we chronicle the evolution of Coarray Fortran 2.0 as it gains support for asynchronous point-to-point and collective operations. We outline how these operations are implemented and describe code fragments from several benchmark programs to show we use these operations to hide latency by overlapping communication and computation.