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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.

    http://www.phoronix.com/vr.php?view=26809

  • #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
      http://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
                    http://www.michaellarabel.com/

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