Summing ASCII encoded integers on Haswell at almost the speed of memcpy
blog.mattstuchlik.com
Summing ASCII encoded integers on Haswell at almost the speed of memcpy
1–10 of 41 posts
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#2I think the trick with dereferencing unmapped memory is cool, but I only really care about techniques that work reliably and I can use in production.
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#3I think the trick with dereferencing unmapped memory is cool, but I only really care about techniques that work reliably and I can use in production.
To be clear, it’s not dereferencing unmapped memory, I just haven’t shown how it’s being mapped, because it’s a little complex. As I note in the post, you can imagine as if I mmap all the necessary addresses at the start of the program.
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#4Knew it'd be SIMD. Such an underrated feature of modern CPUs. Hopefully with cross-platform SIMD in Rust and Golang, it'll be more commonly used.
Thinking parallel gets you enormous speed benefits for any number of arbitrary algorithms: https://mcyoung.xyz/2023/11/27/simd-base64/
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#5I think the trick with dereferencing unmapped memory is cool, but I only really care about techniques that work reliably and I can use in production.
[flagged]
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#6[flagged]
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#7Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#8I think the trick with dereferencing unmapped memory is cool, but I only really care about techniques that work reliably and I can use in production.
To be clear, it’s not dereferencing unmapped memory, I just haven’t shown how it’s being mapped, because it’s a little complex. As I note in the post, you can imagine as if I mmap all the necessary addresses at the start of the program.
Given that the input is "integers uniformly sampled from [0, 2³¹−1]" couldn't you use a LUT for the 99.99% case of just 10/9/8 digit numbers instead and have a cold branch the handle the very rare smaller numbers.
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#9First time I hear about HighLoad. Seems really interesting to me on the first glance. I personally find SIMD and ISA/μarch-specific optimizations more rewarding than pure algorithmic challenges (codeforces and such).
Though Haswell seems like a pretty obsolete platform to optimize for at this point. Even Skylake will be a decade old next year.
Re: Summing ASCII encoded integers on Haswell at almost the speed of memcpy
#10First time I hear about HighLoad. Seems really interesting to me on the first glance. I personally find SIMD and ISA/μarch-specific optimizations more rewarding than pure algorithmic challenges (codeforces and such). Though Haswell seems like a pretty obsolete platform to optimize for at this point. Even Skylake will be a decade old next year.
[deleted]