Agner`s CPU blog

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Future instruction set: AVX-512
Author: Elhardt Date: 2013-10-25 15:57
Hello Agner. You've mentioned most of the important improvements that AVX512 with bring us. However, you've missed an important one that I also think should have been mentioned. AVX512 will include reciprocal estimates that are accurate to 2 ^ -28. That means for single precision floating point, no time consuming Newton-Raphson refinement needs to be done. This can be a major speed boost for division ( and square roots also have the more accurate estimation too ). Intel's divisions have gotten a lot faster over the years to the point where they appear to be faster than the reciprocal / Newton-Raphson method. But now it looks like using the new reciprocal estimation is a way to leap ahead of divide instructions to gain more speed again.
 
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