RIKEN Center for Computational Science


The 185th R-CCS Cafe -partⅠ

The 185th R-CCS Cafe -partⅠ
Date and Time: Mon. Dec. 2, 2019, 13:00 - 13:40
Place: Lecture Hall (6th floor) at R-CCS

Title: Parallel Multigrid Methods on Manycore Clusters with IHK/McKernel
Speaker: Kengo Nakajima (Deputy Director, RIKEN Center for Computational Science)
*Online seminar on BlueJeans

Presentation Language: English
Presentation Material: English


The parallel multigrid method is expected to play an important role in large-scale scientific computing on exa-scale supercomputer systems. Previously we proposed Hierarchical Coarse Grid Aggregation (hCGA), which dramatically improved the performance of the parallel multigrid solver when the number of MPI processes was O(10^4) or more. Because hCGA can handle only two layers of parallel hierarchical levels, the computation overhead due to coarse grid solver may become significant when the number of MPI processes reaches O(10^5)- O(10^6) or more. In the present work, we propose AM-hCGA (Adaptive Multilevel hCGA) that can take into account multiple layers of three or more levels, and show preliminary results using the Oakforest-PACS (OFP) system by JCAHPC. Additionally, we also examine the impact of a lightweight multi-kernel operating system, called IHK/McKernel, for parallel multigrid solvers running on OFP.

This is a joint work with Balazs Gerofi (RIKEN R-CCS), Yutaka Ishikawa (RIKEN R-CCS), and Masashi Horikoshi (Intel).