# ned14/llfio

P1031 low level file i/o and filesystem library for the C++ standard

Repository: https://github.com/ned14/llfio
Canonical: https://ross.abutalabs.com/products/llfio
Homepage: https://ned14.github.io/llfio/
Language: C++
License: NOASSERTION
License Family: other
Last push: 2026-08-24T12:18:23+00:00

## Health v2 (maintenance only)
Score: 85/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 59, longevity 100
- inputs: {"age_days": 4615, "days_push": 9, "days_rel": 119, "gap_med": 114.0, "n_releases_24m": 5}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1047, forks 56 (observed 2026-08-28T04:03:22.150298+00:00)

## What it is
LLFIO is a low-level file I/O and filesystem library for C++17/20, originally proposed for the C++ standard (P1031). It provides zero-copy, race-free, low-overhead file operations with strong support for storage class memory and directly mapped non-volatile storage.

## Use cases
- perform low-latency file i/o in C++ with minimal syscall overhead
- write portable filesystem algorithms across Windows, Linux and macOS
- work with directly mapped non-volatile storage like Intel Optane
- avoid TOCTOU races in filesystem code
- do file i/o with exceptions and RTTI disabled
- maximize IOPS for 4Kb random transfers on fast storage

## When to choose
- you need very low per-operation i/o overhead (~100ns) in C++
- you target SCM/DAX or NVMe storage and want portable filesystem algorithms
- you need race-free, zero-malloc filesystem operations with preserved error codes

## When to avoid
- you just need simple high-level file reading/writing - std::filesystem or your language's stdlib suffices
- you need a stable C++ standard API - the standardisation effort was abandoned in 2025
- you work outside C++ or need a managed-language library

## Facets
- artifact type: library
- maturity: stable
- function: file-system, developer-tools
- domain: developer-tools, files, performance
- platform: cpp, windows, cross-platform
- tags: file-io, filesystem, low-latency, storage-class-memory, dax, cpp17, zero-copy, standardisation-proposal, linux, macos

## Member repositories
- ned14/llfio (main) score 85

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:22.150298+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:01:08.488255+00:00, confidence not recorded.
  - readme: https://github.com/ned14/llfio (fetched 2026-08-28T04:03:22.150298+00:00, sha 7d4758f50793)
  - homepage: https://ned14.github.io/llfio/ (fetched 2026-08-29T13:02:27.306753+00:00, sha 0942cb823ce5)
- Data as of 2026-08-30T08:39:29.467469+00:00.