Finding a needle in a 4 GB haystack: from 0.75 GB/s to 49 GB/s in Go
A recent exploration in Go programming achieved a significant speedup in reading a large file containing mostly zeros. By optimizing the reading process, the speed increased from 0.75 GB/s to 49 GB/s through various techniques. This exercise highlights the impact of different methods on performance in data processing tasks.
- ▪The initial naive method achieved a speed of 0.75 GB/s by reading the entire file into memory and scanning each byte.
- ▪By using larger chunks and optimizing the read process, the speed improved to 13.7 GB/s, demonstrating the benefits of reducing system calls.
- ▪The final optimized method reached 49 GB/s, showcasing the effectiveness of leveraging Go's new simd/archsimd package for performance enhancements.
Opening excerpt (first ~120 words) tap to expand
I had a 4 GiB file that’s almost entirely zeros, exactly one non-zero int64 is hiding at offset Size - 8 (the last aligned slot). The task: find that offset, as fast as possible, in Go on Linux.It’s a deliberately silly problem. There’s no parsing, no indexing, no cleverness on the algorithm side. The only thing it measures is how much data we can pull through a CPU per second. Exactly the kind of micro-task that exposes every layer of the stack: the Go runtime, the standard library, the kernel, the page cache, the memory hierarchy, and SIMD, including Go 1.26’s brand-new simd/archsimd package that lets you write AVX-512 in pure Go.Starting from the most obvious os.ReadFile + for range we get 0.75 GB/s.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Segflow.
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