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Glibc Picks Up Some More FMA Performance Optimizations

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  • Glibc Picks Up Some More FMA Performance Optimizations

    Phoronix: Glibc Picks Up Some More FMA Performance Optimizations

    The GNU C Library, glibc, has picked up support for some additional functions as FMA-optimized versions...

    Phoronix, Linux Hardware Reviews, Linux hardware benchmarks, Linux server benchmarks, Linux benchmarking, Desktop Linux, Linux performance, Open Source graphics, Linux How To, Ubuntu benchmarks, Ubuntu hardware, Phoronix Test Suite

  • #2
    You do realize FMA comes from AMD originally as FMA4 and later FMA3 for both Intel and AMD, right? FMA3 has been in Piledriver and newer CPUs include Zen.

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    • #3
      Originally posted by Marc Driftmeyer View Post
      You do realize FMA comes from AMD originally as FMA4 and later FMA3 for both Intel and AMD, right? FMA3 has been in Piledriver and newer CPUs include Zen.
      Right. Your point?
      Michael Larabel
      https://www.michaellarabel.com/

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      • #4
        Originally posted by Michael View Post
        Right. Your point?
        he seems angry because you he thinks you didn't give AMD proper credit for the FMA, in the "The FMA instruction set is present since Intel Haswell and AMD Piledriver generations" sentence.

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        • #5
          Some of the "other" improvements are pretty impressive. It is good that people are reviewing this older code for improvements.

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          • #6
            Originally posted by Marc Driftmeyer View Post
            You do realize FMA comes from AMD originally as FMA4 and later FMA3 for both Intel and AMD, right? FMA3 has been in Piledriver and newer CPUs include Zen.
            That's accurate. Though, IIRC, both Intel and AMD began working on it around the same time, but didn't communicate with one another. Intel began working with FMA4 switching to FMA3 later on while AMD began working on FMA3 and then switched to FMA4. All that was before any of the two had announced the instruction to the public. When AMD announced FMA4 Intel has already switched to working on FMA3 and released FMA3 some years later (around 2 years after AMD had released FMA4). Since then, with AMD's worse market share and developers picking up FMA3 over FMA4, AMD ended up having to implement FMA3 as well. As of Zen, FMA4 has been deprecated. It seems the instruction still works if you submit it to the CPU but the result is wrong.

            I remember doing some research on the subject a while ago and that's what I remember from it.
            Last edited by andrebrait; 22 October 2017, 09:37 PM.

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            • #7
              Originally posted by Marc Driftmeyer View Post
              You do realize FMA comes from AMD originally as FMA4 and later FMA3 for both Intel and AMD, right? FMA3 has been in Piledriver and newer CPUs include Zen.
              And neither did invent the FMA in the first place, it was a widely known term in HPC. Anyone can fuse MUL and ADD..

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              • #8
                AMD and Intel both failed at industrial espionage. The reason why Intel got FMA3 and AMD, FMA4, is that AMD spied on Intel and wanted to make a compatible implementation so they replaced there FMA3 for FMA4. Intel did the same, they was able to spy on AMD and saw that they where implementing FMA3, so they replaced there FMA4 implementation for FMA3. They ended up just reverting there implementation and failed to stay compatible to there main competitor.

                I don't know if that will append again as both corporation got better security..

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                • #9
                  Originally posted by RavFX View Post
                  AMD and Intel both failed at industrial espionage. The reason why Intel got FMA3 and AMD, FMA4, is that AMD spied on Intel and wanted to make a compatible implementation so they replaced there FMA3 for FMA4. Intel did the same, they was able to spy on AMD and saw that they where implementing FMA3, so they replaced there FMA4 implementation for FMA3. They ended up just reverting there implementation and failed to stay compatible to there main competitor.

                  I don't know if that will append again as both corporation got better security..
                  It wasn't spying. AMD proposed FMA3 for SSE5, Intel wanted something AVX compatible with 4 arguments and suggested FMA4 which AMD then implemented. Intel then changed their mind or decided to screw AMD and implemented FMA3. But it was a public discourse, except for their internal reasoning.

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                  • #10
                    Originally posted by wizard69 View Post
                    Some of the "other" improvements are pretty impressive. It is good that people are reviewing this older code for improvements.
                    Too bad it's mostly for i386 though.

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