Mixed Precision Solver Scalable to 16000 MPI Processes for Lattice Quantum Chromodynamics Simulations on the Oakforest-PACS System

Autor: Boku, Taisuke, Ishikawa, Ken-Ichi, Kuramashi, Yoshinobu, Meadows, Lawrence
Rok vydání: 2017
Předmět:
Druh dokumentu: Working Paper
Popis: Lattice Quantum Chromodynamics (Lattice QCD) is a quantum field theory on a finite discretized space-time box so as to numerically compute the dynamics of quarks and gluons to explore the nature of subatomic world. Solving the equation of motion of quarks (quark solver) is the most compute-intensive part of the lattice QCD simulations and is one of the legacy HPC applications. We have developed a mixed-precision quark solver for a large Intel Xeon Phi (KNL) system named "Oakforest-PACS", employing the $O(a)$-improved Wilson quarks as the discretized equation of motion. The nested-BiCGSTab algorithm for the solver was implemented and optimized using mixed-precision, communication-computation overlapping with MPI-offloading, SIMD vectorization, and thread stealing techniques. The solver achieved 2.6 PFLOPS in the single-precision part on a $400^3\times 800$ lattice using 16000 MPI processes on 8000 nodes on the system.
Comment: 7 pages, submitted to LHAM'17 "5th International Workshop on Legacy HPC Application Migration" in CANDAR'17 "The Fifth International Symposium on Computing and Networking" and to appear in the proceedings. v2:typos corrected
Databáze: arXiv