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August 26, 2012

Adapteva chip has 50 gigaflops per watt

HPCWire - Chipmaker Adapteva is sampling its 4th-generation multicore processor, known as Epiphany-IV. The 64-core chip delivers a peak performance of 100 gigaflops and draws just two watts of power, yielding a stunning 50 gigaflops/watt. The engineering samples were manufactured by GLOBALFOUNDRIES on its latest 28nm process technology.

Epiphany is essentially a stripped down general-purpose RISC CPU that throws out almost everything but the number-crunching silicon. But since it doesn't incorporate features needed by operating systems, like memory management, it relies on a host processor to feed it application kernels in the same manner as a GPGPU. The current implementation supports single precision floating point only, but plans are already in the works for a double precision implementation.

The general layout of Epiphany is a 2D mesh of simple cores, which talk to each other via a high-speed interconnect. In that sense, it looks more like Intel's manycore Xeon Phi than a graphics processor, but without the x86 ISA baggage (but also without the benefit of the x86 ecosystem).

NVIDIA's new K10 GPU computing card can hit about 20 single precision gigaflops/watt, but that also includes 8GB of GDDR5 memory and a few other on-board components, so it's not an apples-to-apples comparison.

Developers can now use standard OpenCL source to program the Epiphany processor



Adapteva's market aspirations extend beyond the military-industrial complex though. Olofsson believes Epiphany is ideal for mobile computing, and eventually HPC. With regard to the former, Adapteva is planning to use the new chip to demonstrate face detection, an application aimed at devices like smartphones and tablets. Face detection and recognition rely on very compute-intensive algorithms, which is fine if you've got a server or two to spare, but it's beyond the number-crunching capabilities of most mobile-grade CPUs and GPUs today.

Other flop-hungry applications that could find a home on in this market include augmented overlays, gesture recognition, real-time speech recognition, realistic game physics, and computational photography. Like mobile-based face detection/recognition, all of these require lots of computational performance operating within very restricted power envelopes.

For high performance computing, the path is a little more complex. For starters, someone has to build a Epiphany-based PCIe card suitable for HPC servers, and then an OEM has to be enticed to support that board. To deliver a reasonable amount of computation for a server -- say, a teraflop or so -- you would need multiple Epiphany chips glued to a card, which would necessitate a PCIe expansion setup of some sort. Not an impossibility, but probably not a job for a do-it-yourselfer.

More fundamentally though, the architecture has to add support for double precision floating point to be taken seriously for HPC (although applications like seismic modeling, image and audio processing, and video analysis are fine with single precision). In any case, double precision is already on Adapteva's roadmap. "We'll definitely have something next year," says Olofsson.

Beyond that, the company has plans on the drawing board to scale this architecture up to the teraflop/watt realm. Following a Moore's Law trajectory, that would mean that by 2018 a 7nm Epiphany processor could house 1,000 cores and deliver a whopping two teraflops. Since such a chip would draw the same two watts as the current 100 gigaflops version, it could easily provide the foundation for an exascale supercomputer. Or a killer tablet.



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