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  • S_x96x_S

    addikt

    a legutolsó AMD-s sérülékenység javítása ( KPTI )
    - Az Intel is hasonlóan sérülékeny a KPTI miatt.
    - az AMD nem javasolja a fixet.. ( de a paranoidok használni fogják )
    - ha valaki bekapcsolja .. akkor lesz teljesítményvesztés ..
    - Játékokban minimális hatása van az FPS-re.

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    "The "What If" Performance Cost To Kernel Page Table Isolation On AMD CPUs"
    https://www.phoronix.com/scan.php?page=article&item=if-amd-kpti&num=1

    It's also worth mentioning that besides AMD not recommending any mitigation changes at this time, external Linux kernel developers so far have not proposed any kernel patches changing any page table isolation behavior or the defaults. So for now just take these results for hypothetical scenario if KPTI needs to be flipped on for AMD CPUs or are very paranoid about security and side with the researchers about the need to enable it. It's also possible that should improved page table isolation become necessary, AMD or other parties may suggest enhancements or alternatives to the existing KPTI code.
    ...
    Gaming and other graphical workloads showed little difference in the resulting FPS performance, similar to KPTI on Intel.
    ...
    ...

    "That is the very quick overview of the Linux kernel's current Kernel Page Table Isolation (KPTI) performance on an AMD Ryzen 9 5900X desktop for reference purposes. But to reiterate, while the TU Graz security researchers have suggested otherwise, AMD's official security bulletin says no further mitigations are required at this time. Hopefully it stays that way and the Linux kernel PTI implementation proves unnecessary for AMD CPUs. If things change there is also the possibility of some enhanced or alternative approach that could alter the impact, so for now we'll just sum it up as the Ryzen 9 5900X performance overhead of "pti=on" for Linux 5.15."

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