Summit is eight times more powerful than ORNL’s previous Titan system and is built with 4,608 IBM compute servers, each containing two 22-core IBM Power9 processors and six NVIDIA Tesla V100 graphics processing unit accelerators, interconnected with dual-rail Mellanox EDR 100Gb/s InfiniBand. Summit also has 10 Pbytes of memory paired with fast, high-bandwidth links for efficient data movement. All this provides a peak performance of 215 petaflops compared to Titan which delivered 27 petaflops in 2012, and makes Summit currently the fastest supercomputer.
However, power consumption is the limiting factor for such machines, and the power consumption of 15MW for Summit puts the system at 14.3 Gflops/watt, which ranks it at number 5 in the current Green 500 listing from November 2017. That list is being revised at the moment, so the ranking may fall further as more power efficient systems are evaluated.
The most power efficient supercomputers are all developed by PEZY Computing in Japan. The Shoubu system B installed at RIKEN’s Advanced Center for Computing and Communication in Japan achieved a power efficiency of 17.0 gigaflops/watt, while the Suiren2 cluster at the High Energy Accelerator Research Organization/KEK, also in Japan, reached 16.8 gigaflops/watt while PEZY’s own Sakura system achieved 16.6 gigaflops/watt. All of these top three systems are positioned in the bottom half of the TOP500 performance with Shoubu at 258, Surien2 at 306 and Sakura at 275.
The closest comparison is at number four in the list is the DGX SaturnV Volta system at NVIDIA’s headquarters in San Jose, California which achieved 15.1 gigaflops/watt, using similar GPU technology to Summit and Xeon processors from Intel, but this comes in at number 149 on the TOP500 performance list.