Fugaku (supercomputer)

Fugaku 富岳 is a petascale supercomputer at the Riken Center for Computational Science in Kobe, Japan. It started development in 2014 as the successor to the K computer and made its debut in 2020. It is named after an alternative name for Mount Fuji. It became the fastest supercomputer in the world in the June 2020 TOP500 list as well as becoming the first ARM architecture-based computer to achieve this. At this time it also achieved 1.42 exaFLOPS using the mixed fp16/fp64 precision HPL-AI benchmark. It started regular operations in 2021. Fugaku was superseded as the fastest supercomputer in the world by Frontier in May 2022. The supercomputer is built with the Fujitsu A64FX microprocessor. This CPU is based on the ARM version 8.2A processor architecture, and adopts the Scalable Vector Extensions for supercomputers. Fugaku was aimed to be about 100 times more powerful than the K computer (i.e. a performance target of 1 exaFLOPS). The initial (June 2020) configuration of Fugaku used 158,976 A64FX CPUs joined using Fujitsu's proprietary torus fusion interconnect. An upgrade in November 2020 increased the number of processors. Fugaku will use a "light-weight multi-kernel operating system" named IHK/McKernel. The operating system uses both Linux and the McKernel light-weight kernel operating simultaneously and side by side. The infrastructure that both kernels run on is termed the Interface for Heterogeneous Kernels (IHK). The high-performance simulations are run on McKernel, with Linux available for all other POSIX-compatible services. Besides the system software, the supercomputer has run many kinds of applications, including several benchmarks. Running the mainstream HPL benchmark, used by TOP500, Fugaku is at petascale and almost halfway to exascale. Additionally, Fugaku has set world records on at least three other benchmarks, including HPL-AI; at 2.0 exaflops, the system has exceeded the exascale threshold for the benchmark.