Comment by loeg

5 days ago

You need to do the exact same kinds of thing in C/C++/Rust. I believe Rust struct layout is not guaranteed to match program order unless you use an annotation forcing it (repr(C)). (So to answer the question: it's great; as good as any other language for micromanaging layout.)

4 comments

loeg

Reply
0x457  5 days ago

Yes, without repr(C) order and padding isn't guaranteed. You would use https://docs.rs/crossbeam-utils/latest/crossbeam_utils/struc... or similar to force fields not being on the same cache line.

  • jasonthorsness  4 days ago

    huh TIL

    "On modern Intel architectures, spatial prefetcher is pulling pairs of 64-byte cache lines at a time, so we pessimistically assume that cache lines are 128 bytes long."