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by 3cats-in-a-coat 932 days ago
What's the TLDR on how... hardware performs differently on two software runtimes?
2 comments
pornel 932 days ago
AMD's implementation of `rep movsb` instruction is surprisingly slow when addresses are page aligned. Python's allocator happens to add a 16-byte offset that avoids the hardware quirk/bug.
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sound1 932 days ago
thank you, upvoted!
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lynndotpy 932 days ago
One of the very first things in the article is a TLDR section that points you to the conclusion.

> In conclusion, the issue isn't software-related. Python outperforms C/Rust due to an AMD CPU bug.

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j16sdiz 932 days ago
It is software-related. Just the CPU perform badly on some software instruction.
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xuanwo 932 days ago
FSRM is a CPU feature embedded in the microcode (in this instance, amd-ucode) that software such as glibc cannot interact with. I refer to it as hardware because I consider microcode a part of the hardware.
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