Collective communication for the RISC-V xBGAS ISA extension

Parallel programming methodologies are fundamentally dissimilar to those of conventional programming, and software developers without the requisite skillset often find it difficult to adapt to these new methods. This is particularly true for parallel programming in a distributed address space, which is necessary for any meaningful degree of scalability. As such, an approach that combines a more intuitive interface together with excellent performance within the distributed address space model is desired. In this work, we present our initial API design and implementation as well as the underlying algorithms for a collective communication library built for the Extended Base Global Address Space (xBGAS) extension to the RISC-V microarchitecture. Our runtime library is designed to enact the Partitioned Global Address Space model (PGAS) in an attempt to alleviate the difficulty associated with traditional distributed address space programming while the underlying collective implementation is formulated to prevent the loss of, and even improve, performance over traditional solutions.