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AVX-512: A "Hidden Gem"?

Accepted submission by takyon at 2017-06-30 21:33:37
Software

Upcoming Intel processors will support scalable AVX-512 [wikipedia.org] instructions, which one former Intel employee [hpcwire.com] calls a "hidden gem" [hpcwire.com]:

Imagine if we could use vector processing on something other than just floating point problems. Today, GPUs and CPUs work tirelessly to accelerate algorithms based on floating point (FP) numbers. Algorithms can definitely benefit from basing their mathematics on bits and integers (bytes, words) if we could just accelerate them too. FPGAs can do this, but the hardware and software costs remain very high. GPUs aren't designed to operate on non-FP data. Intel AVX introduced some support, and now Intel AVX-512 is bringing a great deal of flexibility to processors. I will share why I'm convinced that the "AVX512VL" capability in particular is a hidden gem that will let AVX-512 be much more useful for compilers and developers alike.

Fortunately for software developers, Intel has done a poor job keeping the "secret" that AVX-512 is coming to Intel's recently announced Xeon Scalable processor line very soon. Amazon Web Services has publically touted AVX-512 on Skylake as coming soon!

It is timely to examine the new AVX-512 capabilities and their ability to impact beyond the more regular HPC needs for floating point only workloads. The hidden gem in all this, which enables shifting to AVX-512 more easily, is the "VL" (vector length) extensions which allow AVX-512 instructions to behave like SSE or AVX/AVX2 instructions when that suits us. This is a clever and powerful addition to enable its adoption in a wider assortment of software more quickly. The VL extensions mean that programmers (and compilers) do not need to shift immediately from 256-bits (AVX/AVX2) to 512-bits to use the new bit/byte/word manipulations. This transitional benefit is useful not only for an interim, but also for applications which find 256-bits more natural (perhaps a small, but important, subset of problems).

Will it be enough to stave off "Epyc" [arstechnica.com]?


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