New Orleans, LA — A new supercomputer, L-CSC from the GSI Helmholtz Center, emerged as the most energy-efficient (or greenest) supercomputer in the world, according to the 16th edition of the twice-yearly Green500 list of the world’s most energy-efficient supercomputers. The L-CSC cluster was the first and only supercomputer on the list to surpass 5 gigaflops/watt (billions of operations per second per watt). It was powered by Intel Ivy Bridge CPUs and a FDR Infiniband network and accelerated by AMD FirePro S9150 GPUs.

In fact, the top three slots of the Green500 were powered by three different accelerators with number one, L-CSC, being powered by AMD FirePro S9150 GPUs; number two, Suiren, powered by PEZY-SC many-core accelerators; and number three, TSUBAME-KFC, powered by NVIDIA K20x GPUs. Beyond these top three, the next 20 supercomputers were also accelerator-based.

L-CSC achieved the first position on the November 2014 Green500 List with an impressive 5.27 gigaflops per watt. This system used Intel Ivy Bridge CPUs, AMD FirePro GPUs, and energy-efficient software design to achieve this feat. Suiren, a supercomputer from the High Energy Accelerator Research Organization/KEK in Japan, occupied the second spot at 4.95 gigaflops per watt. Like L-CSC, it used Intel Ivy Bridge CPUs, but coupled them with many-core accelerators from PEZY-SC. Finally, TSUBAME-KFC, which was the most energy-efficient supercomputer over the previous two editions of the Green500, came in third in this edition of the Green500. TSUBAME-KFC was the first supercomputer to have broken the 4 gigaflops/watt barrier. Like the other two accelerator-based machines, it used Intel Ivy Bridge CPUs, but coupled with NVIDIA K20x GPUs.

Other highlights from this Green500 List include the following:

• This marks the first time that a supercomputer (L-CSC) using AMD GPUs has held the top spot.
• The Suiren supercomputer is the first system designed with custom accelerators to enter the top five since November of 2010, when the GRAPE-DR supercomputer achieved the same feat.
• The PEZY-SC many-core accelerators in the Suiren supercomputer each contain 1,024 processing elements that use a pair of ARM926 cores as controller cores. This is the first such system on the Green500 that features many-core technology from a manufacturer other than AMD, Intel, or NVIDIA.

Assuming that L-CSC’s energy efficiency could be scaled linearly to an exaflop supercomputing system, one that can perform one trillion floating-point operations per second, such a system would consume on the order of 190 megawatts (MW). “Although this 190-megawatt power envelope is still far from DARPA’s optimistic target of a 67-megawatt power envelope, it is approximately 16 times better than the initial projection of a nearly 3000-megawatt power envelope from 2007 when the first official Green500 list was launched,” says Wu Feng of the Green500.

About the Green500

The Green500 has provided a ranking of the most energy-efficient supercomputers in the world since November 2007. For decades, the notion of supercomputer “performance” has been synonymous with “speed.” This particular focus has led to the emergence of supercomputers that consume egregious amounts of electrical power and produce so much heat that extravagant cooling facilities must be constructed to ensure proper operation. In addition, when there is an emphasis on speed as the ultimate metric, it often comes at the expense of other performance metrics, such as energy efficiency, reliability, availability and usability. As a result, there has been an extraordinary increase in the total cost of ownership (TCO) of a supercomputer. Consequently, the Green500 seeks to raise the awareness in energy efficiency of supercomputing and to drive it as a first-order design constraint on par with speed.