MPI performance guidelines for scalability

Abstract

MPI (Message Passing Interface) is most widely used parallel programming paradigm. It is used for application development on small as well as large high-performance computing systems. MPI standard provides a specification for different functions but it does not specify any performance guarantee for implementations. Nowadays, its various implementations from both vendors and research groups are available. Users are expecting consistent performance from all implementations and on all platforms. In literature, performance guidelines are defined for MPI communication, IO functions and derived data types. By using these guidelines as a base we have defined guidelines for scalability of MPI communication functions. Also, we have verified these guidelines by using benchmark application and on different MPI implementations such as MPICH, open MPI. The experimental results show that point to point communication functions are scalable. It is quite obvious as in point to point communication the only pair of processes is involved. Hence these guidelines are defined as performance requirement by considering the semantics of these functions. All processes are involved in collective communication functions; therefore defining performance guidelines for collective communication is difficult. In this paper, we have defined the performance guidelines by considering the amount of data transferred in the function. Also, we have verified our defined guidelines and reasons for violations of these guidelines are elaborated.