Reducing Communication in Algebraic Multigrid with Multi-step Node Aware Communication [article]

Amanda Bienz, Luke Olson, William Gropp
2019 arXiv   pre-print
Algebraic multigrid (AMG) is often viewed as a scalable O(n) solver for sparse linear systems. Yet, parallel AMG lacks scalability due to increasingly large costs associated with communication, both in the initial construction of a multigrid hierarchy as well as the iterative solve phase. This work introduces a parallel implementation of AMG to reduce the cost of communication, yielding an increase in scalability. Standard inter-process communication consists of sending data regardless of the
more » ... nd and receive process locations. Performance tests show notable differences in the cost of intra- and inter-node communication, motivating a restructuring of communication. In this case, the communication schedule takes advantage of the less costly intra-node communication, reducing both the number and size of inter-node messages. Node-centric communication extends to the range of components in both the setup and solve phase of AMG, yielding an increase in the weak and strong scalability of the entire method.
arXiv:1904.05838v2 fatcat:artym4ja6jf3nkuykmmatqmlum