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The Performance Cost Of Spectre / Meltdown / Foreshadow Mitigations On Linux 4.19

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  • The Performance Cost Of Spectre / Meltdown / Foreshadow Mitigations On Linux 4.19

    Phoronix: The Performance Cost Of Spectre / Meltdown / Foreshadow Mitigations On Linux 4.19

    One of the most frequent test requests recently has been to look at the overall performance cost of Meltdown/Spectre mitigations on the latest Linux kernel and now with L1TF/Foreshadow work tossed into the mix. With the Linux 4.19 kernel that just kicked off development this month has been continued churn in the Spectre/Meltdown space, just not for x86_64 but also for POWER/s390/ARM where applicable. For getting an overall look at the performance impact of these mitigation techniques I tested three Intel Xeon systems and two AMD EPYC systems as well as a virtual machine on each side for seeing how the default Linux 4.19 kernel performance -- with relevant mitigations applied -- to that of an unmitigated kernel.

    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
    Typo:

    Originally posted by phoronix View Post
    7~16% lower than an umitigated kernel
    Also, why are the results pictures rather than SVG graphs?

    (DejaVu Sans is the worst font)

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    • #3
      Originally posted by tildearrow View Post
      Typo:



      Also, why are the results pictures rather than SVG graphs?

      (DejaVu Sans is the worst font)
      Fixed, thanks.

      Working on some graph code/infrastructure improvements and while those WIP changes were being made, easier just doing this article as pictures.
      Michael Larabel
      https://www.michaellarabel.com/

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      • #4
        Thanks for doing these comparisons!
        To me it confirms that AMD is the wiser choice :-)

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        • #5
          Originally posted by fhuberts View Post
          Thanks for doing these comparisons!
          To me it confirms that AMD is the wiser choice :-)
          For sure, especially in the datacenter. Low single-digit percent impact on AMD, with up to 20% impact on intel. Ouch. EPYC is shaping up to be a real winner for AMD.

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          • #6
            You should do a new test with the old intel-microcode 20171117.1, which was the last release without any spectre patches. The up-to-date microcode also lows the performance.

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            • #7
              thanks for the benchmarking michael

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              • #8
                Originally posted by ipsirc View Post
                You should do a new test with the old intel-microcode 20171117.1, which was the last release without any spectre patches. The up-to-date microcode also lows the performance.
                Yes that would be nice to also include in the tests with or without microcode fixes.

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                • #9
                  In addition to the relative values posted here, are the absolute values from each test also available?

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                  • #10
                    Originally posted by captainohair View Post
                    In addition to the relative values posted here, are the absolute values from each test also available?
                    Yep, http://openbenchmarking.org/result/1...WN82&obr_imw=y As always things are transparent with Phoronix Test Suite and OpenBenchmarking.org.
                    Michael Larabel
                    https://www.michaellarabel.com/

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