Parallel solvers for dense linear systems for heterogeneous computational clusters

Abstract

This paper describes the design and the implementation of parallel routines in the heterogeneous ScaLAPACK library that solve a dense system of linear equations. This library is written on top of HeteroMPI and ScaLAPACK whose building blocks, the de facto standard kernels for matrix and vector operations (BLAS and its parallel counterpart PBLAS) and message passing communication (BLACS), are optimized for heterogeneous computational clusters. We show that the efficiency of these parallel routines is due to the most important feature of the library, which is the automation of the difficult optimization tasks of parallel programming on heterogeneous computing clusters. They are the determination of the accurate values of the platform parameters such as the speeds of the processors and the latencies and bandwidths of the communication links connecting different pairs of processors, the optimal values of the algorithmic parameters such as the total number of processes, the 2D process grid arrangement and the efficient mapping of the processes executing the parallel algorithm to the executing nodes of the heterogeneous computing cluster. We describe this process of automation followed by presentation of experimental results on a local heterogeneous computing cluster demonstrating the efficiency of these solvers.