The design and implementation of SOLAR, a portable library for scalable out-of-core linear algebra computations

SOLAR is a portable high-perfonnance library for out-of-core dense matrix computations. It combines portability with high perfonnance by using existing high-perfonnance in-core subroutine libraries and by using an optimized matrix input-output library. SOLAR works on parallel computers, workstations, and personal computers. It supports in-core computations on both shared-memory and distributed-memory machines, and its matrix input-output library supports both conventional 1/0 interfaces and parallel 110 interfaces. This paper discusses the overall design of SOLAR, its interfaces, and the design of several important subroutines. Experimental results show that SOLAR can factor on a single workstation an out-of-core positive-definite symmetric matrix at a rate exceeding 215 Mflops, and an out-of-core general matrix at a rate exceeding 195 Mflops. Less than 16% of the running time is spent on 110 in these computations. These results indicate that SOLAR's portability does not compromise its perfonnance. We expect that the combination of portability, modularity, and the use of a high-level 110 interface will make the library an important platfonn for research on out-of-core algorithms and on parallel 110.