The thing that differentiates MIC from ATI or Nvidia GPGPUs is that it's front end is a X86 core, therefore the same programming model can apply for both the main CPU and the accelerator, rather than resorting to OpenCL or CUDA. On the other hand, the first MIC cores are based on a 64-bit enhanced version of the 16 year old Pentium that fronts a very wide SIMD FP unit, whose dual-issue in-order instruction approach limits the maximum achievable FP rates. Intel will surely fix that in the next round, but using the X86 as a front end, with all the associated baggage, remains a double-edged sword.
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