this post was submitted on 08 Apr 2024

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"Clean" Code, Horrible Performance in Rust (chrs.dev)

submitted 7 months ago by chrs to c/rust

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[–] [email protected] 7 points 7 months ago (2 children)

It would be interesting to see if an iterator instead of a manual for loop would increase the performance of the base case.

My guess is not, because the compiler should know they are equivalent, but would be interesting to check anyway.

[–] Deebster 2 points 7 months ago (1 children)

I wonder if the compiler checks to see if the calls are pure and are therefore safe to run in parallel. It seems like the kind of thing the Rust compiler should be able to do.

[–] [email protected] 5 points 7 months ago

If by parallel you mean across multiple threads in some map-reduce algorithm, the compiler will not do that automatically since that would be both extremely surprising behavior and in most cases, would make performance worse (it'd be interesting to see just how many shapes you'd need to iterate over before you start seeing performance benefits from map-reduce). If you're referring to vectorization, then the Rust compiler does automatically do that in some cases, and I imagine it depends on how the area is calculated and whether the implementation can be inlined.

[–] onlinepersona 1 points 7 months ago* (last edited 7 months ago) (1 children)

Do you mean this for loop?

for shape in &shapes {
  accum += shape.area();
}

That does use an iterator

for-in-loops, or to be more precise, iterator loops, are a simple syntactic sugar over a common practice within Rust, which is to loop over anything that implements IntoIterator until the iterator returned by .into_iter() returns None (or the loop body uses break).

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[–] arendjr 9 points 7 months ago (2 children)

I think they meant using for accumulating, like this:

shapes.iter().map(Shape::area).sum()

[–] [email protected] 4 points 7 months ago

Yes. That's what I meant.

Though I heavily expect the rust compiler to produce identical assembly for both types of iteration.

[–] onlinepersona 2 points 7 months ago (1 children)

Oh, I see. That would be interesting to benchmark too 👍

Anti Commercial AI thingy

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[–] [email protected] 2 points 7 months ago (1 children)

Anti Commercial AI thingy

Off-topic, but does that actually work? I would assume OpenAI would just ignore it and you'd have to prove that they did so.

[–] onlinepersona 5 points 7 months ago (1 children)

Dunno if it works. AI has been tricked into revealing it's training data, so it's possible that it happens and they are sued for using copyrighted material.

This is my drop in the ocean.

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[–] [email protected] 2 points 7 months ago (1 children)

Maybe I'll join you. :)

[–] onlinepersona 3 points 7 months ago (1 children)

Welcome 🙂 A drop more.

Btw, if you're using linux and X11, you can bind a keyboard shortcut to the following shell-script (probably will need to install xte).

#!/usr/bin/env bash
sleep 0.5
xte "str Anti Commercial AI thingy"xte "key Return"
xte "str [CC BY-NC-SA 4.0](https://creativecommons.org/licenses/by-nc-sa/4.0/)"
xte "key Return"
xte "str "

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[–] [email protected] 3 points 7 months ago (1 children)

I'm on Wayland, but I'm sure I can figure something out.

I do most of my lemmy-ing on mobile, so I'll probably make a bot to auto-edit my posts or something.

[–] onlinepersona 3 points 7 months ago

Have fun! I'm curious how you'll do it. If you figure out a way on Wayland, it would be great to read about it!

Anti Commercial AI thingy

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