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.
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| Original publisher | Segflow |
| Canonical URL | https://segflow.github.io/post/fast-file-search-go/ |
| Publication time | Sat, 30 May 2026 10:56:01 +0000 |
| Retrieval time | 2026-05-30T11:12:09.147Z |
| Last seen | 2026-05-30T11:12:09.147Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | th9tqyGZdf5p |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
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| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
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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