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AMD Retpoline Benchmarks From FX To Threadripper & EPYC

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  • #11
    Originally posted by boxie View Post

    I noted the same on the 1800X - it gains a small performance boost. that's cool
    This is cool. If there is nothing odd going on here most AMD users will be better off with these patches. That is a surprise and will make AMD's chips look a little better vs Intels. Of course it is still early days for these mitigations.


    • #12
      Originally posted by phred14 View Post

      I never did a full recompile for the move to gcc-5.4 - I don't remember seeing that in the instructions. My systems seemed to run just fine. It's moot now, because I've just finished a full recompilation with gcc-6.4.

      I have six systems running Gentoo, and do it all native on each machine. I'm thinking of moving some of my infrastructure to Pi-type stuff in the near future, and for that I'll likely use some sort of build-host.
      Should have been in one of the news items.
      Caused most of things to recompile iirc.
      Later that year gcc 6.4.0. came and the new profile that switched PIE on. I guess we'll soon see the next.

      Six machines is quite a number, though, if they're fast it's probably acceptable.
      But if you have several desktop machines, and some of the low power (but also lower numbercrunching power) it starts to hurt. Or generally elderly systems. Pure command line systems are fine, I compile most stuff there natively, or some are thin clients anyway with an easily exchangeable CF card for chroot compiling on the big box. But a full KDE (+qt and stuff) on something like an E-350 based notebook... meh. It's possible but you can't use the device for a few days on a total recompile. (So I ended up unscrewing the SSD from it and doing the compilation on the big box. )

      GCC 5 uses the new C++ ABI by default. When building new code, you might run
      into link time errors that include lines similar to:
      ...: undefined reference to '_ZNSt6chrono12steady_clock3nowEv@GLIBCXX_3.4.17'

      Or you might see linkage failures with "std::__cxx11::string" in the output.

      These are signs that you need to rebuild packages using the new C++ ABI.
      You can quickly do so by using revdep-rebuild (from gentoolkit).

      For gentoolkit-0.3.1 or higher:
      # revdep-rebuild --library '' -- --exclude gcc

      For previous versions of gentoolkit:
      # revdep-rebuild --library 'libstdc\+\+\.so\.6' -- --exclude gcc

      For more details, feel free to peruse:

      Gentoo allows users to have multiple versions of gcc installed and we (mostly?) support systems where userland is partially build with different versions.  There are both advantages and disadvantag…
      Stop TCPA, stupid software patents and corrupt politicians!