Replace sort implementations by Voultapher · Pull Request #124032 · rust-lang/rust
github.com
This PR replaces the sort implementations with tailor-made ones that strike a balance of run-time, compile-time and binary-size, yielding run-time and compile-time improvements. Regressing binary-s...
 name                                            diff %  speedup 
 slice::sort_large_random                       -65.49%   x 2.90 
 slice::sort_large_strings                      -37.75%   x 1.61 
 slice::sort_medium_random                      -47.89%   x 1.92 
 slice::sort_small_random                        11.11%   x 0.90 
 slice::sort_unstable_large_random              -47.57%   x 1.91 
 slice::sort_unstable_large_strings             -25.19%   x 1.34 
 slice::sort_unstable_medium_random             -22.15%   x 1.28 
 slice::sort_unstable_small_random              -15.79%   x 1.19
  • KillTheMule
    5·
    5 months ago

    only affect very select use cases

    I did not read the whole conversation, but sorting seems a very common usecase (not mine, but seems to me a lot of people sort data), so this seems quite a broad improvement to me.

    that is already perceived as a pain point

    Note though, as is mentioned in the issue, that the survey showed people still prioritize runtime performance over compilation performance in general, so this tradeoff seems warranted.

    the total regression is still minor

    It’s not unheard of that regressions can be unmade later on, so here’s hoping :)

    • arendjr
      5·
      5 months ago

      Yeah, sorting is definitely a common use case, but note it also didn’t improve every sorting use case. Anyway, even if I’m a bit skeptical I trust the Rust team that they don’t take these decisions lightly.

      But the thing that lead to my original question was: if the compiler itself uses the std sorting internally, there’s also additional reason to hope that it might have transitive performance benefits. So even if compiling the Rust compiler with this PR was actually slower, compiling again with the resulting compiler could be faster since the resulting compiler benefits from faster sorting. So yeah, fingers crossed 🤞

      • KillTheMule
        5·
        5 months ago

        transitive performance benefits

        I would have assumed the benchmark suite accounts for that, otherwise the results aren’t quite as meaningfull really. Which ties back you your 2nd senctence: I certainly trust the rust team more than myself on these things :)