I f you have lemons, you make lemonade. That’s what Intel will be doing with its x86 architecture when it comes to Larrabee, a massive multicore solution that will take aim at high-performance graphics rivals such as NVidia and AMD/ATI (see the figure).
While NVidia and AMD/ATI are taking their graphics processing unit (GPU) offerings into the more general computational realm (see “What Will You Do With 1 TFLOLOPS Of Double-Precision Power” at ED Online 19324), Intel is moving in on their turf.
Intel discussed its Larrabee architecture at last month’s Intel Developers Forum (IDF) in San Francisco, but real silicon isn’t available quite yet. Still, Larrabee highlights Intel’s commitment to the x86 architecture. It also opens opportunities in the graphical space, its original target, as well as massively parallel multicore solutions.
The architecture uses a pair of 512-bit communication rings that feed data through a pair of memory controllers, an array of x86 cores with coherent L2 cache, and some fixed-function, texture-sampling control units that enhance graphics processing.
This setup differs significantly from the more dedicated GPU platforms, but it’s very similar to IBM’s Cell architecture (see “Cell Processor Gets Ready To Entertain The Masses,” ED Online 9748). The Cell uses eight custom processors with local memory, while Larrabee offers automatic memory management via hardware.
Intel contends that the CPU array provides a more flexible programming environment, giving developers more control and enabling them to tackle problems in ways that couldn’t be done easily with a GPU-style architecture. Demonstrations at IDF included 3D game-style environments with real-time, ray trace rendering of reflections.
Intel has a long track record with in-order, Pentium-style architectures, and the quad-thread x86 cores will be similar. Larrabee also makes compiler optimization easier since the compiler has to deal with a smaller, deterministic pipeline. It has vector-processing support as well.
A rendering subsystem is included, as the architecture targets graphic displays. Still, its CPU roots may make it a more desirable general computing platform. Experiments with Larrabee show linear performance scaling for many of its targeted applications.
Larrabee will likely give NVidia and AMD second thoughts about improving their platforms. Both companies have a head start in graphics, but this has never stopped Intel from challenging incumbent technologies. Larrabee will also blend well with Intel’s Thread Building Blocks, which initially were designed for the x86 multicore environment (see “Threads Make The Move To Open Source,” ED Online 16538).
Larrabee will boot its own micro operating system. It initially will support the DirectX and OpenGL application programming interfaces (APIs), which are the most popular APIs available on the PC. While it may be a little sour for some designers, Larrabee will be a refreshing change for most.
Intel • www.intel.com
