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October 28, 2010

New Chinese GPGPU Super Outruns Jaguar

Michael Feldman

The end of the US dominance at the top of the TOP500 appears to be at hand. Tianhe-1A, a new Chinese supercomputer powered by over 7,000 NVIDIA Tesla GPUs has recorded a Linpack score of 2.507 petaflops. That would beat out Oak Ridge National Lab’s 1.759 petaflop Jaguar machine, the current TOP500 title holder, by a wide margin.

It would also be the first time a non-US supercomputer held the number one spot in six years. From June 2002 to June 2004, Japan’s Earth Simulator was the fastest supercomputer in the world. In September 2004, it yielded its title to the new kid on the block — IBM’s Blue Gene/L. The US has never looked back.

Until now.

Tianhe-1AThe concentrated performance available in high end discrete GPUs has opened up the petaflop club for a lot more players. But to get to the top of the heap, you need thousands of GPUs. Tianhe-1A, for example, sports 7,168 of them, in this case, NVIDIA Tesla M2050 (Fermi) GPUs. These represent the lion’s share of FLOPS in the system, despite the presence of accompanying 14,336 CPUs. Tianhe-1A also comes with 262 TB of memory and 2 PB of Lustre-based storage.

Although the Linpack performance is a stunning 2.5 petaflops, the system left a lot of potential FLOPS in the machine. Its peak performance is 4.7 petaflops, yielding a Linpack efficiency of just over 50 percent. To date, this is a rather typical Linpack yield for GPGPU-accelerated supers. Because the GPUs are stuck on the relatively slow PCIe bus, the overhead of sending calculations to the graphics processors chews up quite a few cycles on both the CPUs and GPUs.

By contrast, the CPU-only Jaguar has a Linpack/peak efficiency of 75 percent. Even so, Tianhe-1A draws just 4 megawatts of power, while Jaguar uses nearly 7 megawatts and yields 30 percent less Linpack.

Despite the exotic nature and stature of Tianhe-1A system, it is targeted for typical high performance computing applications including oil exploration, equipment development, biomedical research, animation design, weather forecasting, financial risk analysis, remote sensing, materials research, and the like.

Like its immediate ancestor, Tianhe-1, the Tianhe-1A system was developed by the National University of Defense Technology (NUDT) and is being housed at National Supercomputer Center in Tianjin. Tianhe-1, though, was built using AMD GPUs, specifically 2,560 dual-GPU ATI Radeon HD 4870 X2 processors. That system was launched in 2009. Somewhere along the line, NUDT decided to switch horses and go with NVIDIA gear. Since there is currently no CUDA port for AMD GPUs, software compatibility between the two systems is going to problematic, unless they go the OpenCL route.

China’s enthusiasm for GPGPUs has propelled its supercomputing capacity significantly. Even before Tianhe-1A, the country claimed three systems in the top 20: Nebulae at number 2, Tianhe-1 at number 7, and Mole 8.5 at number 19, all of which use GPUs. The US, Germany, and the UK currently have no GPU-equipped systems on the TOP500.

Although the official list results won’t be revealed until the middle of November, it’s doubtful if a secret supercomputer is lying in wait ready to challenge a 2.5 petaflop machine. But we’ll find out soon enough.