Title
Scaling Structured Multigrid to 500K+ Cores through Coarse-Grid Redistribution.
Abstract
The efficient solution of sparse, linear systems resulting from the discretization of partial differential equations is crucial to the performance of many physics-based simulations. The algorithmic optimality of multilevel approaches for common discretizations makes them good candidates for an efficient parallel solver. Yet, modern architectures for high-performance computing systems continue to challenge the parallel scalability of multilevel solvers. While algebraic multigrid methods are robust for solving a variety of problems, the increasing importance of data locality and cost of data movement in modern architectures motivates the need to carefully exploit structure in the problem. Robust logically structured variational multigrid methods, such as black box multigrid, maintain structure throughout the multigrid hierarchy. This avoids indirection and increased coarse-grid communication costs typical in parallel algebraic multigrid. Nevertheless, the parallel scalability of structured multigrid is challenged by coarse-grid problems where the overhead in communication dominates computation. In this paper, an algorithm is introduced for redistributing coarse-grid problems through incremental agglomeration. Guided by a predictive performance model, this algorithm provides robust redistribution decisions for structured multilevel solvers. A two-dimensional diffusion problem is used to demonstrate the significant gain in performance of this algorithm over the previous approach that used agglomeration to one processor. In addition, the parallel scalability of this approach is demonstrated on two large-scale computing systems, with solves on up to 500K+ cores.
Year
DOI
Venue
2018
10.1137/17M1146440
SIAM JOURNAL ON SCIENTIFIC COMPUTING
Keywords
Field
DocType
multigrid,structure,parallel,scalability,stencil
Black box (phreaking),Discretization,Linear system,Computer science,Parallel computing,Theoretical computer science,Solver,Grid,Multigrid method,Scalability,Computation
Journal
Volume
Issue
ISSN
40
4
1064-8275
Citations 
PageRank 
References 
2
0.37
7
Authors
3
Name
Order
Citations
PageRank
Andrew Reisner120.37
Luke Olson223521.93
J. David Moulton33612.31