Visualizing CPU Pipelining (2024)
timmastny.com

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83 points

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flipacholas

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17 hours ago

10 comments

inetknght ・ 15 hours ago

The best presentation I've seen about CPU performance related to pipelining, branch prediction, and speculative execution was Chandler Carruth's "Going Nowhere Faster" presentation at CppCon 2017 [0]. I do recommend watching the whole presentation, but if you watch nothing else then just watch the 5 minutes or so from the linked timestamp.

[0]: https://youtu.be/2EWejmkKlxs?t=2511

  • omcnoe ・ 13 hours ago

    It also contains a wonderfully prescient question asked right at the end of the talk: "... the processor gonna speculate, doing some loads out of the bounds of the array, how does it work in the hardware that it doesn't crash?"

    Left unanswered at the time. I believe Spectre was known but not publicly disclosed at this time.

smallpipe ・ 14 hours ago

CPUs haven't worked like that in anything but a microcontroller for half a century

  • alain94040 ・ 13 hours ago

    Correct (well, maybe not half a century, maybe 30 years or so). I was just about to reply that I'd love a version of this that shows instructions going in and out of a re-order buffer. That would be enlightening.

  • userbinator ・ 7 hours ago

    The tiny MIPS (or compatible) cores in things like cheap router SoCs might still be like that.

risingedge ・ 15 hours ago

If anyone is interested, at https://sonic-rv.ics.jku.at/ we built an educational platform for web-based simulation and visualization of RISC-V processor architectures.

Our pipeline visualization is reconstructed from real RTL traces (you can run your on programs which are simulated using GHDL).

Under examples you can find some different architectures based on the Harris&Harris book on computer architecture.

empiricus ・ 16 hours ago

Maybe it's just me, but the visualizations do not help me at all.

  • artemonster ・ 15 hours ago

    I am always puzzled by such articles - its actually very well made, drawings are good, little interactive pipeline animations are fine. But in order to follow it you must already know and understand what its writeen about and if you dont - the content is just noise for you.

    • cogman10 ・ 15 hours ago

      The article does say what it expects you to know before reading. However, it has a dead link to the knowledge it wants you to know.

jhallenworld ・ 15 hours ago

Now do a dynamic scheduling out of order engine with renaming, 20 pipes, speculative execution and hundreds of instructions in flight. I guess you could make a multi-person game for this.