Platform-Independent SIMD in Go

(go.dev)

65 points | by yurivish 1 hour ago

4 comments

  • qprofyeh 1 hour ago
    This feature opens many doors for optimizing low-level performance in Go projects, that are already running multicore. IIRC there aren’t a lot of languages with built-in std lib support for SIMD and variants. Love the way Go is trying new stuff lately.
    • pjmlp 36 minutes ago
      Besides the usual C and C++, we have Java, .NET, D, Zig, Julia, Swift, Rust.

      So yeah, also appreciate have Go in the group instead of manually having to write Assembly.

      However not many languages adopt ways to manually write SIMD, because most of us have no idea how to write good SIMD code in first place, I surely don't.

      • stingraycharles 20 minutes ago
        Even with languages that adopt ways to manually write SIMD, it’s mostly left to library maintainers rather than application developers.

        I work for a C++ timeseries database startup that leverages SIMD about as much as we possibly can, and except for some extremely rare places we just use libraries.

        • pjmlp 1 minute ago
          Yeah, that is what I have heard from some NVidia folks as well, like Bryce Adelstein, use the libraries as much as possible, and leave the kernels for experts.

          However even then, it depends on how the libraries API surface looks like.

      • Thaxll 14 minutes ago
        With AI I'm pretty sure SIMD will be easier to integrate when necessary.
    • abirch 52 minutes ago
      Vectorizing computations has been Matlabs secret sauce.
      • KeplerBoy 35 minutes ago
        Does matlab these days do stuff like JIT operator fusing to avoid memory roundtrips and take advantage of FMAs?
      • mastermage 46 minutes ago
        Julia does that too.
  • fatty_patty89 10 minutes ago
    The problem with Go isn't performance but with the C/C++ interop overhead, even with the "30% less overhead" from a few updates ago which isnt true for 99% of cases, it isnt enough
  • karolist 9 minutes ago
    Already using this for foreground estimation of cutouts in my project, around 30% speedup over non-SIMD, but the algorithm is probably not very optimised yet.
  • physicsguy 1 hour ago
    Oh this is great, it was one of my biggest bugbears about Go since you almost always have to link C/C++ code to get the appropriate performance.

    The one negative I'd say is that often autovectorisation is 'good enough' and this doesn't really tackle that gap.

    • typical182 31 minutes ago
      FWIW, there is some pretty substantial autovectorization work that is already in-flight for the Go compiler.

      There's a CL stack here:

      https://go.dev/cl/791740

      It's hard to make predictions with an open source project, but my personal guess is some flavor of it will land (including it is already demonstrating good results without an enormous level of code complexity in the compiler and without overly slowing down compile speeds), but I guess we'll see.

      It's being driven by an external contributor who has landed some good changes in the past to the Go compiler. (I think the autovectorization work might be part of their PhD or other academic research, but not sure.)

    • tgv 53 minutes ago
      As a first step, it might be possible to write a linter rule that rewrites suitable numeric loops to SIMD. There are already rules to rewrite several loop types, so that should be doable.
    • pjmlp 35 minutes ago
      The poor Assembler and the unsafe package forgotten in the corner.

      While reaching out to CGO is the easier way, it doesn't mean it is the only tool available in Go.