LU Factorization: Towards Hiding Communication Overheads with a Lookahead-Free Algorithm

Abstract

Lookahead is a well-known technique for masking communication in matrix factorization, but at the cost of complicating application software. We present a new approach, based on automated code-restructuring, that realizes the benefits of lookahead while avoiding the complications. We apply our technique to HPL, the Linpack benchmark used to assess the performance of supercomputers. Starting with the simpler non-lookahead version of the application, we are able to meet the performance of lookahead on the Stampede mainframe.