K Computer
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K Computer

K computer
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ActiveJune 2011 - August 2019
SponsorsMEXT, Japan Japan
LocationRiken Advanced Institute for Computational Science
Architecture88,128 SPARC64 VIIIfx processors, Tofu interconnect
Power12.6 MW
Operating systemLinux[1][2]
Speed10.51 petaflops (Rmax)
RankingTOP500: 18th, as of November 2018[3]
Riken Advanced Institute for Computational Science (AICS) in Kobe, which houses the K computer

The K computer – named for the Japanese word/numeral "kei" (?), meaning 10 quadrillion (1016)[4][Note 1] – is a supercomputer manufactured by Fujitsu, currently installed at the Riken Advanced Institute for Computational Science campus in Kobe, Hy?go Prefecture, Japan.[4][5][6] The K computer is based on a distributed memory architecture with over 80,000 compute nodes.[7] It is used for a variety of applications, including climate research, disaster prevention and medical research.[6] The K computer's operating system is based on the Linux kernel, with additional drivers designed to make use of the computer's hardware.[8]

In June 2011, TOP500 ranked K the world's fastest supercomputer, with a computation speed of over 8 petaflops, and in November 2011, K became the first computer to top 10 petaflops.[9][10] It had originally been slated for completion in June 2012.[10] In June 2012, K was superseded as the world's fastest supercomputer by the American IBM Sequoia.[11]

As of June 2019, K is the world's 20th-fastest computer, with the IBM's Summit & Sierra being the fastest supercomputers.[12][3]

As of November 2018, the K computer holds the third place for the HPCG benchmark. It held the first place until June 2018, when it was superseded by Summit & Sierra.[13][14]

The K supercomputer was decommissioned on the 30th of August 2019.[15][16] In Japan, the K computer will be succeeded by the Fugaku, expected to be 100 times faster, scheduled to be operational in 2021.


On 20 June 2011, the TOP500 Project Committee announced that K had set a LINPACK record with a performance of 8.162 petaflops, making it the fastest supercomputer in the world at the time;[4][6][9] it achieved this performance with a computing efficiency ratio of 93.0%. The previous record holder was the Chinese National University of Defense Technology's Tianhe-1A, which performed at 2.507 petaflops.[5] The TOP500 list is revised semiannually, and the rankings change frequently, indicating the speed at which computing power is increasing.[4] In November 2011, Riken reported that K had become the first supercomputer to exceed 10 petaflops, achieving a LINPACK performance of 10.51 quadrillion computations per second with a computing efficiency ratio of 93.2%.[10] K received top ranking in all four performance benchmarks at the 2011 HPC Challenge Awards.[17]

On 18 June 2012, the TOP500 Project Committee announced that the California-based IBM Sequoia supercomputer replaced K as the world's fastest supercomputer, with a LINPACK performance of 16.325 petaflops. Sequoia is 55% faster than K, using 123% more CPU processors, but is also 150% more energy efficient.[11]

On the TOP500 list, it became first on June 2011, falling down through time to lower positions, to eighteenth in November 2018.[13]

K computer holds third place in the HPCG benchmark test proposed by Jack Dongarra, with 0.6027 HPCG PFLOPS in November 2018.[18]


Node architecture

The K computer comprises 88,128 2.0 GHz eight-core SPARC64 VIIIfx processors contained in 864 cabinets, for a total of 705,024 cores,[1][19] manufactured by Fujitsu with 45 nm CMOS technology.[20] Each cabinet contains 96 computing nodes, in addition to six I/O nodes. Each computing node contains a single processor and 16 GB of memory. The computer's water cooling system is designed to minimize failure rate and power consumption.[21]


The nodes are interconnected by Fujitsu's proprietary Torus fusion (Tofu) interconnect. Tofu has a six-dimensional mesh/torus topology, a scalability of over 100,000 nodes, and full-duplex links that have a peak bandwidth of 10 GB/s (5 GB/s per direction). Each node is connected to its own InterConnect Controller (ICC) chip, which contains four Tofu interfaces (one for the node and three for connecting to other ICC chips) and a router. Tofu's six-dimensional mesh/torus topology is abstracted by software to appear as a three-dimensional torus; and is supported by a Tofu-optimized version of the open-source Open MPI Message Passing Interface library.[21][22][23] Users can create application programs adapted to either a one-, two-, or three-dimensional torus network.[24]

File system

The system adopts a two-level local/global file system with parallel/distributed functions, and provides users with an automatic staging function for moving files between global and local file systems. Fujitsu developed an optimized parallel file system based on Lustre, called the Fujitsu Exabyte File System (FEFS), which is scalable to several hundred petabytes.[21][25]

Power consumption

Although the K computer reported the highest total power consumption of any 2011 TOP500 supercomputer (9.89 MW – the equivalent of almost 10,000 suburban homes), it is relatively efficient, achieving 824.6 GFlop/kW. This is 29.8% more efficient than China's NUDT TH MPP (ranked #2 in 2011), and 225.8% more efficient than Oak Ridge's Jaguar-Cray XT5-HE (ranked #3 in 2011). However, K's power efficiency still falls far short of the 2097.2 GFlops/kWatt supercomputer record set by IBM's NNSA/SC Blue Gene/Q Prototype 2. For comparison, the average power consumption of a TOP 10 system in 2011 was 4.3 MW, and the average efficiency was 463.7 GFlop/kW.[9]

According to TOP500 compiler Jack Dongarra, professor of electrical engineering and computer science at the University of Tennessee, the K computer's performance equals "one million linked desktop computers".[5] The computer's annual running costs are estimated at US$10 million.[5]

K Computer Mae rapid transit station

On 1 July 2011, Kobe's Port Island Line rapid transit system renamed one of its stations from "Port Island Minami" to "K Computer Mae" (meaning "In front of K Computer") denoting its vicinity.[26]

See also



  1. ^ a b K computer, SPARC64 VIIIfs 2.0GHz, Tofu interconnect
  2. ^ Moroo, Jun; et al. (2012). "Operation System for the K computer" (PDF). Fujitsu Sci. Tech. J. 48 (3): 295-301.
  3. ^ a b "TOP500 List - November 2018". www.top500.org. November 2018. Retrieved 2018.
  4. ^ a b c d "Japanese 'K' Computer Is Ranked Most Powerful". The New York Times. 20 June 2011. Retrieved 2011.
  5. ^ a b c d "Japanese supercomputer 'K' is world's fastest". The Telegraph. 20 June 2011. Retrieved 2011.
  6. ^ a b c "Supercomputer "K computer" Takes First Place in World". Fujitsu. Retrieved 2011.
  7. ^ "The K computer: Japanese next-generation supercomputer development project". IEEE Xplore. 2011. Retrieved 30 January 2013.
  8. ^ [1] Moroo et al. (2012) Operating System for the K computer. Fujitsu. Retrieved 18 June 2013.
  9. ^ a b c June 2011 TOP500 Supercomputer Sites
  10. ^ a b c "K computer" Achieves Goal of 10 Petaflops". Fujitsu. 2 November 2011. Retrieved 10 November. 2011.
  11. ^ a b "IBM supercomputer overtakes Fujitsu as world's fastest". BBC. 18 June 2012.
  12. ^ "K computer, SPARC64 VIIIfx 2.0GHz, Tofu interconnect | TOP500 Supercomputer Sites". www.top500.org. Retrieved 2019.
  13. ^ a b "TOP500 - K computer, SPARC64 VIIIfx 2.0GHz, Tofu interconnect". Retrieved 2017.
  14. ^ "HPCG - November 2018 | TOP500 Supercomputer Sites". www.top500.org. Retrieved 2018.
  15. ^ Cite error: The named reference k-shutdown was invoked but never defined (see the help page).
  16. ^ "Japan pulls plug on K, once the world's fastest supercomputer, after seven-year run". www.japantimes.co.jp. Retrieved 2019.
  17. ^ ""K computer" No. 1 in Four Benchmarks at HPC Challenge Awards". Riken. 17 November 2011. Retrieved 2011.
  18. ^ "June 2017 HPCG Results". HPCG Benchmark. June 2017. Retrieved 2017.
  19. ^ ""SPARC64(TM) VIIIfx": A Fast, Reliable, Low-power CPU". Fujitsu Global. Retrieved 2013.
  20. ^ Takumi Maruyama (2009). SPARC64(TM) VIIIfx: Fujitsu's New Generation Octo Core Processor for PETA Scale computing (PDF). Proceedings of Hot Chips 21. IEEE Computer Society. Retrieved 2013.
  21. ^ a b c "Riken Advanced Institute for Computational Science" (PDF). Riken. Retrieved 2011.
  22. ^ "Programming on K computer" (PDF). Fujitsu. Retrieved 2011.
  23. ^ "Open MPI powers 8 petaflops". Cisco Systems. Retrieved 2011.
  24. ^ Yuichiro Ajima; et al. (2009). "Tofu: A 6D Mesh/Torus Interconnect for Exascale Computers". Computer. IEEE Computer Society. 42 (11): 36-40. doi:10.1109/MC.2009.370.
  25. ^ "An Overview of Fujitsu's Lustre Based File System" (PDF). Fujitsu. Retrieved 2011.
  26. ^ "Japan's K Supercomputer". Trends in Japan. January 2012. Retrieved 2012.

External links

Preceded by
2.566 petaflops
World's most powerful supercomputer
June 2011 - June 2012
Succeeded by
IBM Sequoia
16.325 petaflops

Coordinates: 34°39?12.1?N 135°13?13.7?E / 34.653361°N 135.220472°E / 34.653361; 135.220472

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.



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