DARPA has issued an RFI (pdf) to help enable what they are calling Ubiquitous High Performance Computing (UHPC). According to the June 2009 TOP500 supercomputer list, the fastest supercomputer available, Roadrunner, runs at just over 1 PFLOP. It uses around 2.5 million watts of electricity and requires around 278 racks of equipment .
DARPA would like to fit the same computational power into one air-cooled rack and use no more than 57,000 watts (including cooling). That’s 100% of Roadrunner’s computational power in 0.4% of the space using 2% of the electrical power. Also, while the most energy efficient system now achieves 536 Mflops/watt , DARPA is looking for 50 Gflops/watt.
What’s more, is that they would like to minimize the overhead associated with thousand-way to billion-way parallelism. Why billion-way parallelism? I suppose this implies an anticipation of systems containing billions of execution units. This may not be unreasonable. For example, take a look at the proposed Sequoia supercomputer, which is proposed to include one million cores.
Beyond these astounding requirements, there are also requests for a “Self Aware OS” that is introspective, goal-oriented, adaptive, self-healing and approximate. I’d recommend reading page eight of the RFI above for more details. The hope is that the system will be able to continue operations in the face of failures and “attack” (see page 4 of RFI).
Well, while the OS and application capabilities will be huge challenges, the restrictions put on the physical aspects of the hardware are also challenging. With GPUs and Cell processors leading to increased computations per watt, perhaps we may be able to significantly improve overall system power efficiencies. In addition, DARPA is looking for this to take place potentially in 9 years (proposals are due by July 27, 2009) if it is feasible. With top supercomputers sometimes becoming more powerful than the 500 most powerful supercomputers combined from four years prior, we can definitely see overall computational ability increase quickly but this doesn’t necessarily translate into the density and energy efficiencies.