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The Current Intel Coffee Lake Mitigation Performance Impact With Linux 5.9

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  • The Current Intel Coffee Lake Mitigation Performance Impact With Linux 5.9

    Phoronix: The Current Intel Coffee Lake Mitigation Performance Impact With Linux 5.9

    Of the many new features in Linux 5.9 with its debut set for this weekend, one of the performance-related changes is Intel FSGSBASE support finally being mainlined. A half-decade after the Linux patches first appeared for this feature present in Intel CPUs going back to Ivy Bridge, the mainline kernel is now patched for this feature that can help out I/O and other context switching heavy workloads. Given many of the same workloads were negatively impacted by the CPU security mitigations of recent years, here is a look at the current mitigated vs. unmitigated performance difference on the Linux 5.9 kernel with an Intel Core i9 9900K CPU for reference on how the mitigation impact is on recent versions of the Linux kernel.

    http://www.phoronix.com/vr.php?view=29588

  • #2
    it's a lot

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    • #3
      This isn't margin of error bad. It's just bad. Death by a hundred security mitigations.

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      • #4
        I'm curious to see if zen3 will finally fixed all the known bugs or we'll have to wait zen7 ...

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        • #5
          Typo:

          Originally posted by phoronix View Post
          IBPB Reptolines for Spectre V2,

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          • #6
            Originally posted by bog_dan_ro View Post
            I'm curious to see if zen3 will finally fixed all the known bugs or we'll have to wait zen7 ...
            I'm curious to see if 14nm++++ will finally fixed all the known bugs or we'll have to wait 14nm+++++++++++++++++++++++++++++ ...

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            • #7
              Include lvi and Intel CPUs can land directly in trash.

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              • #8
                Michael

                Please test Zen 2/3, Ice Lake and Tiger Lake CPUs as well.

                Originally posted by ThoreauHD View Post
                This isn't margin of error bad. It's just bad. Death by a hundred security mitigations.
                Spectre class vulnerabilities affect all OoOE CPUs in the universe, so don't be so harsh on Intel.

                Originally posted by bog_dan_ro View Post
                I'm curious to see if zen3 will finally fixed all the known bugs or we'll have to wait zen7 ...
                And yes Zen 3 will be the same in this regard.
                Last edited by birdie; 10-09-2020, 07:01 PM.

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                • #9
                  It is not that the performance impact of mitigations is lower on newer Intel CPUs, the hardware one is just off the books so it looks better.

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                  • #10
                    Originally posted by tildearrow View Post

                    I'm curious to see if 14nm++++ will finally fixed all the known bugs or we'll have to wait 14nm+++++++++++++++++++++++++++++ ...
                    It's properly fixed in Tiger Lake, it appears: https://www.techradar.com/news/intel...ltdown-attacks

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