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Thread: Meltdown and Spectre impacts on modern compression codecs

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    Meltdown and Spectre impacts on modern compression codecs

    Hi all – Does anyone know if the Meltdown and Spectre patches slow down compression or decompression in general? I'm not clear on what kinds of operations suffer the most slowdowns. I've heard databases are impacted, and certain kinds of I/O, but I've not dug into the details yet.

    Jyrki – Is brotli slower on patched systems? Is Zstd slower? What about something as basic as zlib/gzip?

    Joe

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    Quote Originally Posted by SolidComp View Post
    Hi all – Does anyone know if the Meltdown and Spectre patches slow down compression or decompression in general? I'm not clear on what kinds of operations suffer the most slowdowns. I've heard databases are impacted, and certain kinds of I/O, but I've not dug into the details yet.

    Jyrki – Is brotli slower on patched systems? Is Zstd slower? What about something as basic as zlib/gzip?

    Joe
    I don't know, but I'm very interested to learn about this if anyone can share benchmark results.

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    Input 187,074,408,448 bytes - all Bitcoin blockchain blocks till block 516,394 as .tar
    Output 152,713,202,154 bytes - botli -1

    Virtual Memory = 2 MB
    Physical Memory = 3 MB

    OS boot single core:

    Meltdown and Spectre disabled:

    Kernel User Process Global
    59.890 613.500 673.390 850.586
    62.796 611.000 673.796 848.259
    60.843 613.890 674.734 852.859

    Meltdown and Spectre enabled:

    Kernel User Process Global
    73.687 613.593 687.281 878.694
    74.312 610.078 684.390 885.106
    75.453 611.203 686.656 886.246

    ------------------------------

    OS boot multi core:

    Meltdown and Spectre disabled:

    Kernel User Process Global
    57.187 604.843 662.031 673.131
    59.343 609.437 668.781 679.900
    57.921 606.796 664.718 675.992

    Meltdown and Spectre enabled:

    Kernel User Process Global
    68.890 606.656 675.546 686.262
    68.531 611.375 679.906 699.245
    69.109 604.968 674.078 684.374

    ---------------------------------------------------------------

    Input 187,074,408,448 bytes - all Bitcoin blockchain blocks till block 516,394 as .tar
    Output 148,029,657,529 bytes - zstd -1

    Virtual Memory = 14 MB
    Physical Memory = 17 MB

    OS boot single core:

    Meltdown and Spectre disabled:

    Kernel User Process Global
    42.140 1198.734 1240.875 1370.639
    39.578 1209.593 1249.171 1377.740
    39.125 1210.765 1249.890 1379.169

    Meltdown and Spectre enabled:

    Kernel User Process Global
    45.453 1215.265 1260.718 1398.678
    47.328 1206.718 1254.046 1394.858
    47.687 1196.531 1244.218 1385.758

    ---------------------------------

    OS boot multi core:

    Meltdown and Spectre disabled:

    Kernel User Process Global
    63.687 656.328 720.015 643.378
    64.687 655.453 720.140 633.118
    66.859 654.281 721.140 632.139

    Meltdown and Spectre enabled:

    Kernel User Process Global
    76.062 656.359 732.421 633.314
    74.281 655.250 729.531 648.363
    72.546 656.562 729.109 647.317

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    Definitely a pretty sensible impact.

    Since Meltdown & Spectre mitigation is a kernel topic, I guess most of the extra-load is within kernel-related stuff,
    such as threading, task-switching, and most I/O interactions generally.

    It would be interesting to know more about the sources of these slow-down,
    to understand if user code can do something to reduce triggering them.

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    +1 to know

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    when you disabled the meldtodnw spectra patc h did you do it through the registry or avoide installing the patch all together ?

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    Quote Originally Posted by SvenBent View Post
    when you disabled the meldtodnw spectra patc h did you do it through the registry or avoide installing the patch all together ?
    I did not touched the BIOS and OS patches, I used the InSpectre utility https://www.grc.com/inspectre.htm to disable or enable Meltdown and Spectre before reboot.

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    Spectre/Meltdown fixes in HPC: Want the bad news or the bad news? It's slower, say boffins:
    https://www.theregister.co.uk/2018/0...e_batters_hpc/

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    Intel Gags Customers from Publishing Performance Impact of Microcode Updates:
    https://www.techpowerup.com/247028/i...rocode-updates

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    We have simplified the Intel license to make it easier to distribute CPU microcode updates and posted the new version here:
    https://twitter.com/imadsousou/statu...80311753072640
    https://01.org/mcu-path-license-2018

    Not updated here yet:
    https://downloadcenter.intel.com/dow...code-Data-File

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    Looks like we can expect some more performance loss now that hyperthreading is considered a security risk.
    https://www.theregister.co.uk/2018/0...yperthreading/
    https://www.techspot.com/news/75240-...intel-cpu.html

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    Quote Originally Posted by Sportman View Post
    Memory, network and disk/flash can stop the cpu(s) making progress, and particularly so on multi-core systems. Compression can help with all of these, but a compression system is often a memory system hog, and no benchmarking that I know of looks into the memory system load. I believe the impact of the memory system can be 50-100 % speed differences in multiprocessing scaling. For example, two codecs run in A seconds and B seconds, but if you run 10 copies of these codecs in parallel, the other codec runs in A*2 seconds and the other B*4 seconds.

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    MDS (Micro-architectural Data Sampling) Tool from RIDL (Rogue In-Flight Data Load) Team:
    https://mdsattacks.com/files/mdstool-win.zip
    https://mdsattacks.com/files/mdstool-linux.zip
    https://github.com/vusec/ridl

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