Tile QR factorization with parallel panel processing for multicore architectures

To exploit the potential of multicore architectures, recent dense linear algebra libraries have used tile algorithms, which consist in scheduling a Directed Acyclic Graph (DAG) of tasks of fine granularity where nodes represent tasks, either panel factorization or update of a block-column, and edges represent dependencies among them. Although past approaches already achieve high performance on moderate and large square matrices, their way of processing a panel in sequence leads to limited performance when factorizing tall and skinny matrices or small square matrices. We present a new fully asynchronous method for computing a QR factorization on shared-memory multicore architectures that overcomes this bottleneck. Our contribution is to adapt an existing algorithm that performs a panel factorization in parallel (named Communication-Avoiding QR and initially designed for distributed-memory machines), to the context of tile algorithms using asynchronous computations. An experimental stud...

• Type: Journal
• Year: 2010
• Where: IPPS
• Authors: Bilel Hadri, Hatem Ltaief, Emmanuel Agullo, Jack Dongarra
• Keywords: Distributed And Parallel Computing, IPPS 2010, Multicore Architectures, Panel Factorization, Tile Algorithms