Vectorizing and distributing number‐theoretic transform to count Goldbach partitions on Arm‐based supercomputers

Abstract

SummaryIn this article, we explore the usage of scalable vector extension (SVE) to vectorize number‐theoretic transforms (NTTs). In particular, we show that 64‐bit modular arithmetic operations, including modular multiplication, can be efficiently implemented with SVE instructions. The vectorization of NTT loops and kernels involving 64‐bit modular operations was not possible in previous Arm‐based single instruction multiple data architectures since these architectures lacked crucial instructions to efficiently implement modular multiplication. We test and evaluate our SVE implementation on the A64FX processor in an HPE Apollo 80 system. Furthermore, we implement a distributed NTT for the computation of large‐scale exact integer convolutions. We evaluate this transform on HPE Apollo 70, Cray XC50, HPE Apollo 80, and HPE Cray EX systems, where we demonstrate good scalability to thousands of cores. Finally, we describe how these methods can be utilized to count the number of Goldbach partitions of all even numbers to large limits. We present some preliminary results concerning this problem, in particular a histogram of the number of Goldbach partitions of the even numbers up to 240.