For the fifth consecutive time, Tianhe-2, a supercomputer developed by China’s National University of Defense Technology, has retained its position as the world’s number one system, according to the 45th edition of the twice-yearly TOP500 list of the world’s most powerful supercomputers. Tianhe-2, which means Milky Way-2, led the list with a performance of 33.86 petaflop/s (or quadrillions of calculations per second) on the Linpack benchmark.
At number two was Titan, a Cray XK7 system installed at the U.S. Department of Energy’s Oak Ridge National Laboratory. Titan, the top system in the United States and one of the most energy-efficient systems on the list, achieved 17.59 petaflop/s on the Linpack benchmark.
The only new entry in the Top 10 supercomputers on the latest list is at number seven—Shaheen II is a Cray XC40 system installed at King Abdullah University of Science and Technology, or KAUST, in Saudi Arabia. Shaheen II achieved 5.536 petaflop/s on the Linpack benchmark, making it the highest-ranked Middle East system in the 22-year history of the list and the first to crack the Top 10.
The other nine systems in the top 10 were all installed in 2011 or 2012, and this low level of turnover among the top supercomputers reflects a slowing trend that began in 2008.
A detailed analysis of the latest TOP500 list was presented Monday, July 13, at the 2015 International Supercomputing Conference in Frankfurt, Germany. At that time, the full list was also published at TOP500.org.
The United States remains the top country in terms of overall systems with 233, up from 231 six months ago and the same as in June 2014 and down from 265 on the November 2013 list. The U.S. is nearing its historical low number on the list.
The number of European systems rose to 141, up from 130 on the last list, while the number of systems across Asia dropped to 108 from 120.
The number of Chinese systems on the list also dropped to 37, compared to 61 last November, China has only half as many systems on the newest list as it did one year ago. Japan continues to increase its count on the list, claiming 39 spots this time, up from 32 last November.
However, China’s role in high performance computing is increasing in the manufacturing arena, with Lenovo now being counted among the vendors of systems on the TOP500 list. Three new systems are solely attributed to Lenovo, while 20 systems previously listed as IBM are now labeled jointly between IBM and Lenovo. Cray Inc., a company long associated with supercomputers, is on a resurgence and emerges in the latest list as the clear leader in performance, claiming a 24 percent share of installed total performance (up from 18.2 percent). IBM takes the second spot with a 22.2 percent share, down from 28 percent last November.
Slowing trend in performance growth
Since its inception in June 1993, the TOP500 list has served as a consistent measure of the performance growth of supercomputers, since all systems are ranked according to performance running the same Linpack benchmark application. As noted at the release of the 44th list in November 2014, the overall list-by-list growth rates of performance continues to be at historically low values for the last two years.
This lag in the overall average performance of all 500 systems is noticeably influenced by the low turnover among very large systems at the top of the list. Recent installations of very large systems—up to June 2013—have counteracted the reduced growth rate at the bottom of the list, but with few new systems at the top of the past few lists, the overall growth rate is now slowing. This offers an indication that the market for the very largest systems might currently behave differently from the market of mid-sized and smaller supercomputers.
This is supported by the fact that the performance of the last system on the list (No. 500) has consistently lagged behind historical growth trends for the past five years, a trajectory that now increases by 55 percent each year. Between 1994 and 2008, however, the annual growth rate for the number 500 systems’ performance was 90 percent.
On the latest edition of the list, the number 500 system recorded a performance of 153.6 teraflops (trillions of calculations per second, 133.7 teraflop/s six months ago). The last system on the newest list was listed at position 421 in the previous TOP500. This represents the lowest turnover rate in the list in two decades.
Other highlights from the 45th list
Total combined performance of all 500 systems has grown to 363 petaflop/s, compared to 309 Pflop/s last November and 274 Pflop/s one year ago. This increase in installed performance also exhibits a noticeable slowdown in growth compared to the previous long-term trend.
There are 68 systems with performance greater than one petaflop/s on the list, up from 50 last November.
The No. 1 system, Tianhe-2, and the No. 8 system, Stampede, use Intel Xeon Phi processors to speed up their computational rate. The No. 2 system, Titan, and the No. 6 system, Piz Daint, use NVIDIA GPUs to accelerate computation.
A total of 88 systems on the list are using accelerator/co-processor technology, up from 75 on November 2014. Fifty-two of these use NVIDIA chips, four use ATI Radeon, and there are now 33 systems with Intel MIC technology (Xeon Phi). Four systems use a combination of Nvidia and Intel Xeon Phi accelerators/co-processors.
Ninety-eight percent of the systems use processors with six or more cores and 88.2 percent use eight or more cores.
HP has the lead in the total number of systems with 178 (35.6 percent) compared to IBM with 111 systems (22.2 percent). Last November, HP had 179 systems, and IBM had 153 systems. In the system category, Cray remains third with 71 systems (14.2 percent).
About the TOP500 List
The first version of what became today’s TOP500 list started as an exercise for a small conference in Germany in June 1993. Out of curiosity, the authors decided to revisit the list in November 1993 to see how things had changed. About that time they realized they might be on to something and decided to continue compiling the list, which is now a much-anticipated, much-watched, and much-debated twice-yearly event.
The TOP500 list is compiled by Erich Strohmaier and Horst Simon of Lawrence Berkeley National Laboratory; Jack Dongarra of the University of Tennessee in Knoxville; and Martin Meuer of the ISC Group, Germany.
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