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Comment by Rickasaurus | Hacker News Reader

What's the deal with pidigits? Losing out bad to PHP here even.

Bignum math isn't optimized for performance yet.

See this discussion: http://www.reddit.com/r/rust/comments/1xcq1q/c_gcc_vs_rust_w... There are also already some patches making rust a lot less worse: https://github.com/mozilla/rust/pull/12209

A fix is in the queue. It was a tiny thing. Currently there is an Android buildbot issue that is preventing anything from landing, but hopefully that will be resolved today.

because it's not using GMP

So if I understand correctly, the pidigits test in this case this isn't a self-contained, fully ported microbenchmark, but rather a test of some random Rust code vs. an optimized library[1]?

If that's true, then what's the point of including pidigits if the entire algorithm isn't going to be ported into all target languages?

[1] GMP, The GNU Multiple Precision Arithemtic Library: https://gmplib.org/

It's more of a "testing the platform" rather than the language. You can write a Rust program that runs at exactly the same speed as a C program (the difference here would be clang backend vs. gcc moreso than the choice of language).

That becomes more of a pass/fail test (either you're using the fastest known library or you aren't) which isn't very interesting as a benchmark.

As I understand it, the rule is "if your language comes with a bignum implementation, you must use it, otherwise you may use GMP". I've been seriously tempted to suggest removing our bignum implementation for this reason (though I won't).

Python uses GMP while having a bignum implementation. I believe any language is allowed to use it.

Python: http://benchmarksgame.alioth.debian.org/u64/program.php?test...

Ruby: http://benchmarksgame.alioth.debian.org/u64/benchmark.php?te...

There is no such rule.

When someone contributes a Rust pi-digits program that uses GMP it will be shown (as long as it uses the same algorithm).

We get to see both programs that use GMP and programs that don't.

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