The K computer named for the Japanese word/numeral " manufactured by Fujitsu, installed at the Riken Advanced Institute for Computational Science campus in Kobe, Hyōgo Prefecture, Japan. The K computer was based on a distributed memory architecture with over 80,000 compute nodes. It was used for a variety of applications, including climate research, disaster prevention and medical research. The K computer's operating system was based on the Linux kernel, with additional drivers designed to make use of the computer's hardware. 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. It had originally been slated for completion in June 2012. In June 2012, K was superseded as the world's fastest supercomputer by the AmericanIBM Sequoia. , K is the world's 20th-fastest computer, with the IBM's Summit & Sierra being the fastest supercomputers. , 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 It held the first place until June 2018, when it was superseded by Summit & Sierra. The K supercomputer was decommissioned on the 30th of August 2019. In Japan, the K computer will be succeeded by the Fugaku supercomputer, expected to be up to 100 times faster, scheduled to be operational in 2021.
Performance
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; 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. The TOP500 list is revised semiannually, and the rankings change frequently, indicating the speed at which computing power is increasing. 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%. K received top ranking in all four performance benchmarks at the 2011 HPC Challenge Awards. 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. On the TOP500 list, it became first on June 2011, falling down through time to lower positions, to eighteenth in November 2018. K computer holds third place in the HPCG benchmark test proposed by Jack Dongarra, with 0.6027 HPCG PFLOPS in November 2018.
Specifications
Node architecture
The K computer comprises 88,128 2.0 GHz eight-coreSPARC64 VIIIfx processors contained in 864 cabinets, for a total of 705,024 cores, manufactured by Fujitsu with 45 nm CMOS technology. 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.
Network
The nodes are connected by Fujitsu's proprietary torus fusion interconnect.
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, which is scalable to several hundred petabytes.
Power consumption
Although the K computer reported the highest total power consumption of any 2011 TOP500 supercomputer, it is relatively efficient, achieving 824.6 GFlop/kW. This is 29.8% more efficient than , and 225.8% more efficient than . However, K's power efficiency still falls far short of the 2097.2 GFlops/kWatt supercomputer record set by . 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. 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". The computer's annual running costs are estimated at US$10 million.
On 1 July 2011, Kobe's Port Island Linerapid transit system renamed one of its stations from "Port Island Minami" to "K Computer Mae" denoting its vicinity.
