Dougall

@dougallj

he/they

du.gl
Geregistreerd in februari 2007
61 foto's en video's Foto's en video's

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  1. Vastgemaakte Tweet
    7 mrt.

    I published my research on the Apple M1 CPU microarchitectures (Firestorm and Icestorm), with instruction tables describing throughput, latency, and uops for most instructions, and (an insane number of) detailed experiments and measurements.

    13 antwoorden 239 retweets 797 vind-ik-leuks
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  2. 29 aug.

    Oh, hey, found the screenshot:

    2 retweets 11 vind-ik-leuks
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  3. heeft geretweet
    14 aug.

    Our August 2021 Progress Report is out! It's been a long time coming and we've made a lot of progress in the past few months, so be sure to check it out!

    6 antwoorden 67 retweets 287 vind-ik-leuks
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  4. heeft geretweet
    4 aug.

    Happy to share a little experiment we are trying. I am not sure if it will stick but we will see. Here is how I personally think about the matter 1/?

    9 antwoorden 98 retweets 271 vind-ik-leuks
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  5. heeft geretweet
    31 jul.

    This is the companion paper to uica, which I just finished reading. Beyond the throughput predictor, it has many new (previously either unknown or unconfirmed) details about many Intel microarchitecture generations. Highly recommended!

    Researchers have developed a new simulator to predict the throughput of basic blocks of all Intel Core μarchs released in the last decade, demonstrating to be more accurate than the predictions of state-of-the-art tools by more than an order of magnitude.
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    2 antwoorden 16 retweets 102 vind-ik-leuks
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  6. heeft geretweet
    30 jul.

    Today, I released uiCA, the " Code Analyzer". uiCA is based on data from , combined with a new detailed pipeline model. An online version (that also supports other tools) is available at (1/3)

    5 antwoorden 57 retweets 147 vind-ik-leuks
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  7. heeft geretweet
    20 jul.

    After a month of reverse-engineering, I present documentation on the Arm® Mali™-G78 instruction set. Get it while it's hot 🔥

    8 antwoorden 195 retweets 973 vind-ik-leuks
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  8. heeft geretweet
    28 jun.

    My friend did some fancy cryptanalysis of a hash function and wrote up a detailed explanation, with interactive diagrams and everything:

    2 antwoorden 78 retweets 240 vind-ik-leuks
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  9. 18 jul.

    Oops, there's a typo in the image - the second group of 'v's should be 'p's. I'm also enjoying this old trick of multiplying by 0x0101010101010101 for popcount, which makes sense when you want the prefix sums of the popcounts of each byte.

    3 vind-ik-leuks
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  10. 16 jul.

    And another variant, which would be okay for doing a single vector if clang's implementation of the PMULL2 intrinsic reliably generated a PMULL2:

    2 antwoorden 3 vind-ik-leuks
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  11. 16 jul.

    I've been looking a bit at move-mask replacements on the M1 - I think this variation is new? And I ended up looking at other ARM64 optimisation ideas for simdjson:

    Arm SIMD intrinsics code implementing move-mask for four vectors, using four multiplies by a magic constant, two paired adds, and a table lookup, described in a little more detail at the link.
    1 antwoord 3 retweets 17 vind-ik-leuks
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  12. heeft geretweet
    12 jul.

    Great article by on memory disambiguation for speculative load/store reordering. I keep forgetting how much stuff is on the uarch-bench wiki.

    6 retweets 22 vind-ik-leuks
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  13. heeft geretweet
    10 jul.

    New blog post: "Entropy coding in Oodle Data: the big picture" Relatively short one, first of what will be a series.

    3 antwoorden 27 retweets 112 vind-ik-leuks
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  14. heeft geretweet
    8 jul.

    We're writing a new mach-o linker. Today's Chrome Canary is the first Chrome/Mac release linked with it :)

    7 antwoorden 10 retweets 100 vind-ik-leuks
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  15. heeft geretweet
    7 jul.

    One weird thing you can do with branch prediction/control speculation is to implement value speculation. Here's a demo/benchmark.

    9 antwoorden 18 retweets 128 vind-ik-leuks
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  16. heeft geretweet
    17 sep. 2014

    Honestly, I'm not sure what to conclude from this.

    13 antwoorden 5 retweets 12 vind-ik-leuks
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  17. 8 jun.

    I guess today we find out how many things depend on Fastly

    2 antwoorden 2 retweets 13 vind-ik-leuks
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  18. heeft geretweet
    4 jun.

    Latency, throughput, and port usage data for Rocket Lake is now available at

    2 antwoorden 11 retweets 54 vind-ik-leuks
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  19. heeft geretweet
    1 jun.

    Has someone done "I'm an x86 programmer" / "oh yeah, name 20 instructions" / "MOV" yet?

    16 antwoorden 23 retweets 398 vind-ik-leuks
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  20. heeft geretweet
    26 mei

    For those who liked the M1RACLES name, it really didn't take long to come up with it! Though I think might have been idly thinking of ideas for a few minutes prior too :)

    4 antwoorden 18 retweets 191 vind-ik-leuks
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  21. heeft geretweet
    25 mei

    You don't ship a new operating system every day, but today is that day.

    61 antwoorden 230 retweets 2.281 vind-ik-leuks
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