this post was submitted on 29 Oct 2023
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Programming

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What are some of the best optimizations you applied to your code? (lemmy.world)
submitted 1 year ago* (last edited 1 year ago) by AlmightySnoo@lemmy.world to c/programming@programming.dev
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Got myself a few months ago into the optimization rabbit hole as I had a slow quant finance library to take care of, and for now my most successful optimizations are using local memory allocators (see my C++ post, I also played with mimalloc which helped but custom local memory allocators are even better) and rethinking class layouts in a more "data-oriented" way (mostly going from array-of-structs to struct-of-arrays layouts whenever it's more advantageous to do so, see for example this talk).

What are some of your preferred optimizations that yielded sizeable gains in speed and/or memory usage? I realize that many optimizations aren't necessarily specific to any given language so I'm asking in !programming@programming.dev.

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[–] gens@programming.dev 2 points 1 year ago

I was playing bloons td back when it was flash, in firefox. It was sometimes too slow. So i fired up perf and found out what horrors flash player was doing with memcpy. One byte memcpy, completely unaligned memcpy.

So i wrote an ssse3 memcpy that could do one byte unaligned with xmm registers. It was 30% faster then whatever glibc was doing and made the game playable. Was planing to submit it to glibc, but they came up with something different that was just as fast.