Fujitsu A64FX

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General information
Marketed byFujitsu
Designed byFujitsu
Common manufacturer(s)
Architecture and classification
Min. feature size7 nm
Instruction setARMv8.2-A with SVE and SBBA level 3
Physical specifications
  • 48 per CPU[1] plus optional assistant cores[2][3]

The A64FX is a 64-bit ARM architecture microprocessor designed by Fujitsu.[1][4] The processor is replacing the SPARC64 V as Fujitsu's processor for supercomputer applications.[5] It powers the Fugaku supercomputer, the fastest supercomputer in the world by TOP500 rankings as of June 2020[4][5][6][7] as well as November 2020 and June 2021.


Fujitsu collaborated with ARM to develop the processor; it is the first processor to use the ARMv8.2-A Scalable Vector Extension SIMD instruction set with 512-bit vector implementation.[4] A prototype computer using the processors was ranked as the 159th fastest computer in the world on the TOP500 list in November 2019.[8]

It has "Four-operand FMA with Prefix Instruction",[1] i.e. MOVPRFX instruction followed by FMA3 (ARM, like RISC in general, is a 3-operand machine, doesn't have space for 4 operands), which get packed into a single operation in the pipeline. For the processor the designer claim ">90% execution efficiency in (D|S|H)GEMM and INT16/8 dot product".[1]

The processor uses 32 gigabytes of HBM2 memory with a bandwidth of 1 TB per second.[4] The processor contains 16 PCI Express generation 3 lanes[1] to connect to accelerators (hypothetical e.g. GPUs and FPGAs). The reported transistor count is about 8.8 billion.[4]

Each A64FX processor has 4 NUMA nodes, with each NUMA node having 12 compute cores, for a total of 48 cores per processor.[9][2][3] Each NUMA node also has its own level 2 cache, HBM2 memory, and assistant cores for non-computational purposes.[9]

Fujitsu intends to produce lower specification machines with reduced assistant cores.[2][3] Reliability, availability and serviceability (RAS) capabilities are claimed, i.e. ~128,400 error checkers in total.


Fujitsu designed the A64FX for the Fugaku. As of June and November 2020, the Fugaku is the fastest supercomputer in the world by TOP500 rankings.[10] Fujitsu intends to sell smaller machines with A64FX processors.[2][3] Anandtech reported in June 2020 that the cost of a PRIMEHPC FX700 server, with 2 A64FX nodes, was ¥4,155,330 (c. US$39,000).[11]

Cray is developing supercomputers using the A64FX.[12][13] The Isambard 2 supercomputer is being built for a consortium in the United Kingdom, led by the University of Bristol and also including the Met Office, using the Fujitsu processors.[14][15] It is an upgrade to the Isambard supercomputer which was built with the Marvell ThunderX2, another ARM architecture microprocessor.[15]

Ookami is an open testbed system supported by NSF run by Stony Brook University and the University at Buffalo providing researchers access to A64FX processors.

See also[edit]


  1. ^ a b c d e "Hot Chips 30 conference; Fujitsu briefing" (PDF). Toshio Yoshida. Archived from the original (PDF) on 5 December 2020.
  2. ^ a b c d "Fujitsu Launches New PRIMEHPC Supercomputers Using Fugaku Technology - Fujitsu Global". 13 November 2019. Retrieved 28 June 2020.
  3. ^ a b c d "FUJITSU Supercomputer PRIMEHPC Specifications". Retrieved 28 June 2020.
  4. ^ a b c d e "Fujitsu Successfully Triples the Power Output of Gallium-Nitride Transistors - Fujitsu Global". Fujitsu. Retrieved 8 March 2020.
  5. ^ a b Morgan, Timothy Prickett (24 August 2018). "Fujitsu's A64FX Arm Chip Waves The HPC Banner High". The Next Platform. Retrieved 8 March 2020.>
  6. ^ "Outline of the Development of the Supercomputer Fugaku | RIKEN Center for Computational Science RIKEN Website". Retrieved 18 November 2020.
  7. ^ "Supercomputer Fugaku - Supercomputer Fugaku, A64FX 48C 2.2GHz, Tofu interconnect D | TOP500". Retrieved 18 November 2020.
  8. ^ "A64FX prototype - Fujitsu A64FX, Fujitsu A64FX 48C 2GHz, Tofu interconnect D | TOP500 Supercomputer Sites". Retrieved 8 March 2020.
  9. ^ a b Odajima, Tetsuya; Kodama, Yuetsu; Tsuji, Miwako; Matsuda, Motohiko; Maruyama, Yutaka; Sato, Mitsuhisa (September 2020). "Preliminary Performance Evaluation of the Fujitsu A64FX Using HPC Applications". 2020 IEEE International Conference on Cluster Computing (CLUSTER): 523–530. doi:10.1109/CLUSTER49012.2020.00075. ISBN 978-1-7281-6677-3. S2CID 226266547.
  10. ^ "Supercomputer Fugaku - Supercomputer Fugaku, A64FX 48C 2.2GHz, Tofu interconnect D | TOP500". Retrieved 18 November 2020.
  11. ^ Cutress, Dr Ian (26 June 2020). "HPC Systems Special Offer: Two A64FX Nodes in a 2U for $40k". Retrieved 28 June 2020.
  12. ^ "Cray, Fujitsu Both Bringing Fujitsu A64FX-based Supercomputers to Market in 2020". HPCwire. 13 November 2019. Retrieved 8 March 2020.
  13. ^ Tsukimori, Osamu (7 January 2021). "Japan's Fugaku supercomputer is tackling some of the world's biggest problems". The Japan Times. Retrieved 26 January 2021.
  14. ^ Bristol, University of. "February: GW4 Isambard - News and features - University of Bristol". Retrieved 8 March 2020.
  15. ^ a b Burt, Jeffrey (9 March 2020). "Isambard 2 Is About Driving Technology Diversity". The Next Platform. Retrieved 9 March 2020.