The Barcelona Supercomputer Center is building one of the greenest high-performance computers on the planet, but if Alex Ramirez gets his way, it could also be the most powerful.


Ramirez, a manager with the center, is in the midst of building a new supercomputer, called Mont-Blanc, that will use the same kind of low-power chips that you can find in tablets and smartphones today. Starting next month, his team will start assembling the first Mont-Blanc prototype using Nvidia's Tegra 3 processors instead of the RISC or Intel x86-compatible processors that are used on virtually all of today's supercomputers. The Tegra 3 will handle communications between different parts of the system while the actual number crunching will be done by yet-to-be-determined low-power multicore Nvidia graphics processors similar to the GeForce 520MX.

By June, Ramirez plans to run benchmarks for the widely followed Top500 supercomputer list, which measures how well computers perform a supercomputing benchmark program known as Linpack. But Ramirez says that he's got his eyes on another target: the Green 500 list. This list ranks computers by power efficiency, not raw performance. "There we expect to be in the top 10," Ramirez says.


Last November, the top computer on the Green 500 - a prototpye of IBM's Blue Gene computer at the Thomas J. Watson Research Center - could do just over 2 quadrillion calculations per second (2 gigaflops) per watt. When the Mont-Blanc prototype is up and running next month, it should be closer to 7 gigaflops per watt.

Ramirez is tapping into one of the coolest trends in supercomputing: the drive to use low-power mobile and graphics processors to do high-power computing.

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Because battery life is so important in mobile devices, chips like the Tegra 3 focus on using as little power as possible. The Mont-Blanc Tegra 3 chips will probably run in the 4-watt range. That's nothing compared to an Intel Xeon chip, which can easily burn between 50 and 100 watts.

The trick is that supercomputer programs have to be rewritten in order to take advantage of the GPUs and the Tegra 3. Nvidia has tried to help that along by releasing a software development kit that helps people like Ramirez write programs for its chipsets.


Ramirez expects to be on June's Top500 with a computer that uses between 2,000 and 4,000 processors. "Instead of using very few - but very big performance - processors… we're going to be using a lot of very low-power - but middle performance - processors," he says.

But things get really interesting when Nvidia starts shipping successors to the Tegra 3, including a new 64-bit chip based on a new Cortex A15 design from ARM Holdings. That processor will be able to take on some of the supercomputing workload being done by Ramirez's GPUs right now and it could give him a real breakthrough in performance: four-times the computer processing for essentially the same 4 watts of power.


But to take advantage of this next-generation of chips, the Barcelona Team will need to get their software finely tuned for this new and unproven architecture. They need to run the Linpack benchmark used by the Top500 group, but they'll also need to rewrite the research programs used by the university's scientists: software that simulates intricate chemical and physics problems. That's going to be the tricky part. If his bet pays off, though, Ramirez thinks that this machine could pave the way for the most powerful system on the Top500 list by 2017. "We are working now toward a machine that could be deployed five years from now," he says.

That system would probably be in the 200 Petaflop range - or about 20 times as powerful as the top supercomputer in the world today, Japan's K Computer.


For all of the excitement about Mont-Blanc in the supercomputing world, ARM is sanguine about the project. It sees big bucks in all of those smartphones and tablets that consumers are buying - not in geeky supercomputers.

Last month, ARM president Simon Segars told us that the Barcelona Supercomputing project was "interesting," but he downplayed the supercomputing market. "Supercomputers, for ARM, is not a high volume market," he said. "It's not something we spend a lot of time talking about. Ours is a business that is royalty and unit driven, so we're interested in high-volume markers."


Cade Metz contributed to this story.

Photo: Barcelona Supercomputer Center


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