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by Manishearth 3666 days ago
> some modicum of common sense when reading the numbers on The Benchmark Game

yes, this involves checking what the benchmarks are actually measuring. In this case, it is how much faster SIMD makes things. Factor that in, or rewrite the programs with SIMD in rust, and it should come out to be the same.

> But it appears that it have.

Have you not been listening? It doesn't. The speed differences you quote are due to simd. Rust has simd support, just not in a non-nightly compiler.
2 comments
igouy 3665 days ago
> Have you not been listening? It doesn't. The speed differences you quote are due to simd.

That should be easy to demonstrate!

Please quote the lines in the source-code of these fannkuch-redux and reverse-complement programs that show SIMD use --

http://benchmarksgame.alioth.debian.org/u64q/program.php?tes...

http://benchmarksgame.alioth.debian.org/u64q/program.php?tes...

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bjourne 3666 days ago
Using the nightly builds of any programming language in production is insane. That's why we call it FutureRust to differentiate it from what is production ready Rust.

That Rust might have SIMD intrinsics in the future matters little to people trying to seriously use Rust today. And in several benchmarks C handily beats Rust even without intrinsics. Such as the fannkuch-redux one where it is about 2x faster.

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Manishearth 3665 days ago
Don't use the latest nightly then. Use the nightly from 4 months ago that corresponds to today's stable, ensuring that it doesn't have any extra soundness patches that need backporting. Usually the case.

I don't see "several", I just see one. Most of the non-simd benchmarks have almost exactly the same numbers for Rust and C. Perhaps the Rust test for fannkuch isn't optimized yet (looks like the C one has some extra logic about how to split up the chunks, whereas Rust blindly parallelizes)? I already optimized one Rust program, I'm not going to sit and optimize every benchmark out there -- we have tons of counterexamples of fast benchmarks already. It seems like you won't agree as long as one nonoptimized benchmark exists. In that case, good day to you. I'm done here.

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