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A Look At The Relative Spectre/Meltdown Mitigation Costs On Windows vs. Linux

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  • dungeon
    replied
    Cool to see recently upstream kernels 3.2 and 3.16 get mitigated too:

    Code:
    > cat /proc/sys/kernel/osrelease
    3.16.56
    > cat /sys/devices/system/cpu/vulnerabilities/*
    Not affected
    Mitigation: __user pointer sanitization
    Mitigation: Full AMD retpoline
    Maybe it is time for quarterly all-around recapitulation mitigations aftermath... i mean including older distros, but also Windows 7 because Windows versions other than Windows 10 and nearly 3 years after still represents majorty

    That said and going a bit further maybe to note how 32bit Linux OS (if updated) is same safe now, but only on AMD CPUs since these are not affected by Meltdown and mitigation for that is missing for 32bit

    That is kind of weird to me since Intel had more newer 32bit only CPUs released
    Last edited by dungeon; 23 March 2018, 11:21 PM.

    Leave a comment:

  • treba
    Senior Member

  • treba
    replied
    Originally posted by Venemo View Post
    Are these mitigations still necessary? I thought Intel has released a microcode update to fix it.
    No, they microcode updates only allow certain mechanisms like IBRS, IBPB and STIBP to be used. That is AFAIK only about spectre variant 2 and generally much slower than solutions like retpoline, while arguably being more save.

    So no, especially meltdown is not going to be fixed by microcode updates but only by new hardware. On AMD you don't need have meltdown, so the difference in performance should be much smaller.

    Leave a comment:

  • starshipeleven
    Premium Supporter

  • starshipeleven
    replied
    Originally posted by Venemo View Post
    Are these mitigations still necessary? I thought Intel has released a microcode update to fix it.
    There is no fix, only mitigations that affect performance (microcodes included). A fix would require a change in hardware design, which means most processors for the next year or so will still have this bug.

    Main difference vs microcode is that (opensource) software mitigations are pretty much guaranteed to protect you as their source is available, while microcodes are opaque blobs where you can't be sure of what they do at all.

    This is also the case for Windows.

    Leave a comment:

  • Etherman
    Senior Member

  • Etherman
    replied
    Interesting. I personally choose the performance option.

    Leave a comment:

  • Venemo
    Senior Member

  • Venemo
    replied
    Are these mitigations still necessary? I thought Intel has released a microcode update to fix it.

    Leave a comment:

  • phoronix
    Administrator

  • A Look At The Relative Spectre/Meltdown Mitigation Costs On Windows vs. Linux

    Phoronix: A Look At The Relative Spectre/Meltdown Mitigation Costs On Windows vs. Linux

    The latest in our Windows versus Linux benchmarking is looking at the relative performance impact on both Linux and Windows of their Spectre and Meltdown mitigation techniques. This round of tests were done on Windows 10 Pro, Ubuntu 18.04 LTS, and Clear Linux when having an up-to-date system on each OS where there is Spectre/Meltdown protection and then repeating the same benchmarks after reverting/disabling the security functionality.

    http://www.phoronix.com/vr.php?view=26143
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