Communications of the ACM
Green500 List: Supercomputer Efficiency Continues to Improve
"While the supercomputers on the Green500 are collectively consuming more power, they are using the power more efficiently than before," says Associate Professor Wu Feng of the computer science and the electrical and computer engineering departments at Vi
Credit: Virginia Tech
The fifth edition of Virginia Tech's Green500 List shows that supercomputers continue to use less power even as their capacity soars. Computers raking in top spots a year ago are falling by the wayside to newer models.
"The average energy efficiency of the top supercomputers in the world increased by 10 percent," said Wu Feng, an associate professor within the College of Engineering's computer science and the electrical and computer engineering departments at Virginia Tech, of the latest rankings.
The latest Green500 rankings are available at http://www.green500.org/lists/2009/06/list.php.
The 10 percent increase in energy efficiency translates to a 10 megaflops/watt improvement, rising to 108 megaflops/watt from 98 megaflops/watt recorded in November 2008. (Megaflops stand for millions of floating-point operations per second.) Also, aggregate power of the list increased by 15 percent, to 230 megawatts from 200 megawatts. "While the supercomputers on the Green500 are collectively consuming more power, they are using the power more efficiently than before," Feng added.
The Green500 List serves as a ranking of environmentally friendly, low-energy supercomputers and a complement to the TOP500 Supercomputer List. The Green500 debuted in November 2007 at the 2007 Supercomputing conference to provide a foundation for tracking trends in green supercomputing.
For the first time, the rankings show maximum energy efficiency remaining the same, but three 500-megaflops/watt supercomputers fell out of the Green500. "The three supercomputers that occupied the No. 2 spot on the November 2008 Green500 are no longer computationally powerful enough to be considered among the TOP500 supercomputers in the world, and hence, they dropped off the Green500 List. This occurrence thus provides further fuel to the argument for a 'more inclusive' Green500," Feng said. "If the trend of performance doubling continues, the No. 1 machine on this Green500 is unlikely to make the November 2009 Green500 List."
Topping the list is the BladeCenter QS22 Cluster, PowerXCell 8i 4.0 Gigahertz, Infiniband, operated by the Interdisciplinary Centre for Mathematical and Computational Modeling at the University of Warsaw.
Also significant: More machines range more than 200 megaflops/watt, while fewer machines are less than 50 megaflops/watt. "As more powerful supercomputers supplant the less powerful, these new machines are performing their computations more energy efficiently," Feng said.
Meanwhile, a self-made accelerator-based supercomputer from the National Astronomical Observatory of Japan catapulted into fifth spot. The self-made GRAPE-DR could be the first Green500 supercomputer with more than a million processing elements at 2.097 million, Feng said.
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