Hacker News Reader

Comment by steveklabnik | Hacker News Reader

You can use your usual tools, like perf, on Rust.

What’s the situation with the IO? Are you buffering? Are you holding the lock for a long time or rapidly locking and unlocking?

If you can share the code I can take a look.

View on HN

I realized that stdout was acquiring and releasing a mutex on every write operation; fixing that improved things. The good news is that when writing to /dev/null, it's now faster than the C++ version, but writing to stdout is still ~25% slower. I suppose there's something else suboptimal about the way I'm using stdout, but I haven't figured it out yet.

Code is here: https://gist.github.com/usefulcat/56f334bc58c97edb073b457b68...

There is actually one other file but it only contains a couple of struct definitions for the libpcap file and packet headers. Thanks for having a look!

Update: I wrapped the locked stdout handle in a BufWriter and now the rust version is >25% faster than the C++ version in all cases.

I didn't think there was room for that much improvement; I'm really impressed.

If you have a blog, that would make for an amazing entry, going from 50% slower to 25% faster.

Edit: HOLY CRAP! I have a program written in Rust, ppbert[1], and I just tried wrapping my StdoutLock object in a BufWriter, and I improved the performance of my pretty-printing by a factor of 2x! I knew to use BufReader for files, I didn't know it was helpful for stdin and stdout! Thank you _so much_ for sharing your experience, I've certainly benefited!

    Benchmark #1: ppbert -2 *.bert2
      Time (mean ± σ):      3.816 s ±  0.115 s    [User: 2.494 s, System: 1.321 s]
      Range (min … max):    3.688 s …  4.028 s

    Benchmark #2: ppbert-dev -2 *.bert2
      Time (mean ± σ):      1.728 s ±  0.045 s    [User: 1.493 s, System: 0.234 s]
      Range (min … max):    1.678 s …  1.843 s

    Summary
      'ppbert-dev -2 *.bert2' ran 2.21x faster than 'ppbert -2 *.bert2'

[1] https://github.com/gnuvince/ppbert

Awesome! Glad you got it sorted. Those two things are always footguns...

Reply on news.ycombinator.com