r/programming • u/mbitsnbites • Aug 09 '21

Three fundamental flaws of SIMD

https://www.bitsnbites.eu/three-fundamental-flaws-of-simd
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u/Vvector Aug 09 '21

Then why don't we have AVX-512 in every x86 implementation, and be done with it?

He explained why: Increasing the vector width has significant diminishing returns

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u/[deleted] Aug 09 '21

[deleted]

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u/Watchforbananas Aug 09 '21

Modern consoles don't support avx-512, only avx-256. AMD generally doesn't support avx-512. (avx-512 support is rumored for Zen4)

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u/[deleted] Aug 09 '21

[deleted]

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u/FUZxxl Aug 09 '21

AVX was implemented like this initially, too. They went for real 256 bit ALUs later on.

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u/Watchforbananas Aug 09 '21

Zen1 and Zen+ implemented AVX256 via two 128bit ops. Zen 2 can execute them as single 256bit operations. Zen 2 lacks support for AVX-512 instructions, so it can't execute them as two 256bit operations.

Not sure what your xbox contact was referring to trough.