Linear Complexity $\mathcal{H}^2$ Direct Solver for Fine-Grained Parallel Architectures

Fuente: arXiv
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Autori principali: Boukaram, Wajih, Keyes, David, Li, Sherry, Liu, Yang, Turkiyyah, George
Natura: Preprint
Pubblicazione: 2025
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author Boukaram, Wajih
Keyes, David
Li, Sherry
Liu, Yang
Turkiyyah, George
author_facet Boukaram, Wajih
Keyes, David
Li, Sherry
Liu, Yang
Turkiyyah, George
contents We present factorization and solution phases for a new linear complexity direct solver designed for concurrent batch operations on fine-grained parallel architectures, for matrices amenable to hierarchical representation. We focus on the strong-admissibility-based $\mathcal{H}^2$ format, where strong recursive skeletonization factorization compresses remote interactions. We build upon previous implementations of $\mathcal{H}^2$ matrix construction for efficient factorization and solution algorithm design, which are illustrated graphically in stepwise detail. The algorithms are ``blackbox'' in the sense that the only inputs are the matrix and right-hand side, without analytical or geometrical information about the origin of the system. We demonstrate linear complexity scaling in both time and memory on four representative families of dense matrices up to one million in size. Parallel scaling up to 16 threads is enabled by a multi-level matrix graph coloring and avoidance of dynamic memory allocations thanks to prefix-sum memory management. An experimental backward error analysis is included. We break down the timings of different phases, identify phases that are memory-bandwidth limited, and discuss alternatives for phases that may be sensitive to the trend to employ lower precisions for performance.
format Preprint
id arxiv_https___arxiv_org_abs_2509_11152
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Linear Complexity $\mathcal{H}^2$ Direct Solver for Fine-Grained Parallel Architectures
Boukaram, Wajih
Keyes, David
Li, Sherry
Liu, Yang
Turkiyyah, George
Distributed, Parallel, and Cluster Computing
We present factorization and solution phases for a new linear complexity direct solver designed for concurrent batch operations on fine-grained parallel architectures, for matrices amenable to hierarchical representation. We focus on the strong-admissibility-based $\mathcal{H}^2$ format, where strong recursive skeletonization factorization compresses remote interactions. We build upon previous implementations of $\mathcal{H}^2$ matrix construction for efficient factorization and solution algorithm design, which are illustrated graphically in stepwise detail. The algorithms are ``blackbox'' in the sense that the only inputs are the matrix and right-hand side, without analytical or geometrical information about the origin of the system. We demonstrate linear complexity scaling in both time and memory on four representative families of dense matrices up to one million in size. Parallel scaling up to 16 threads is enabled by a multi-level matrix graph coloring and avoidance of dynamic memory allocations thanks to prefix-sum memory management. An experimental backward error analysis is included. We break down the timings of different phases, identify phases that are memory-bandwidth limited, and discuss alternatives for phases that may be sensitive to the trend to employ lower precisions for performance.
title Linear Complexity $\mathcal{H}^2$ Direct Solver for Fine-Grained Parallel Architectures
topic Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2509.11152