Title
Reproducibility strategies for parallel Preconditioned Conjugate Gradient.
Abstract
The Preconditioned Conjugate Gradient method is often used in numerical simulations. While being widely used, the solver is also known for its lack of accuracy while computing the residual. In this article, we aim at a twofold goal: enhance the accuracy of the solver but also ensure its reproducibility in a message-passing implementation. We design and employ various strategies starting from the ExBLAS approach (through preserving every bit of information until final rounding) to its more lightweight performance-oriented variant (through expanding the intermediate precision). These algorithmic strategies are reinforced with programmability suggestions to assure deterministic executions. Finally, we verify these strategies on modern HPC systems: both versions deliver reproducible number of iterations, residuals, direct errors, and vector-solutions for the overhead of only 29% (ExBLAS) and 4% (lightweight) on 768 processes.
Year
DOI
Venue
2020
10.1016/j.cam.2019.112697
Journal of Computational and Applied Mathematics
Keywords
Field
DocType
65Y05,65Y20,65-05,65K99,68Q10,68W10
Conjugate gradient method,Reproducibility,Residual,Mathematical optimization,Algorithm,Rounding,Solver,Mathematics
Journal
Volume
ISSN
Citations 
371
0377-0427
0
PageRank 
References 
Authors
0.34
0
5
Name
Order
Citations
PageRank
Roman Iakymchuk1325.98
Maria Barreda2727.88
Matthias Wiesenberger3143.18
José Ignacio Aliaga400.34
Enrique S. Quintana-Ortí51317150.59