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axboe/fio

Flexible I/O Tester

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axboe/fio has 6k+ stars and 1k+ forks on GitHub, is written in C, and was last pushed on Oct 12, 2026. Data as of . Signed-in members get hourly updates — create a free account.

Summary Information

Updated 3 hours ago
Type:CLI ToolCategory(s):Debugging & ProfilingGPU, Accelerators & HPCDeveloper Tools
Added to GitGenius on September 10th, 2026
Created on October 22nd, 2012
Open Issues & Pull Requests: 238 (+0)
GitHub issues: Enabled
Number of forks: 1,435
Total Stargazers: 6,395 (+0)
Total Subscribers: 163 (+0)

Repository Insights (GitGenius)

Median issue/PR response: 9.1 hours
Mean response time: 90.0 days
90th percentile: 67.3 days
Tracked items: 183

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Maintainer activity

3 people did triage or write work on this repository in the last 12 months.

Counts unlabeled, assigned, unassigned, milestoned, demilestoned, locked, unlocked over the last 12 months. These are issue and pull request events that require triage or write permission. Commits and code review are not counted. labeled and renamed are excluded because GitHub issue forms record the issue author as the actor. Figures from October 11, 2026. This count is not comparable across projects: each project's automation decides which of these events a person emits.

How this project is maintained

About 16% of issues opened in the past year have never received a reply. 90% of open issues come from outside the core team, so the backlog reflects real-world use rather than internal planning. 60% of issues opened in the past year have been closed, leaving a working backlog. Three people close 82% of everything that gets resolved.

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Issue Activity (beta)

Open issues: 62
New in 7 days: 0
Closed in 7 days: 1
Avg open age: 709 days
Stale 30+ days: 59
Stale 90+ days: 55

Recent activity

Opened in 7 days: 0
Closed in 7 days: 1
Comments in 7 days: 0
Events in 7 days: 0

Top labels

  • needreporterinfo (37)
  • enhancement (27)
  • patcheswelcome (23)
  • triaged (20)
  • needsattention (8)
  • bug (4)
  • windows (3)
  • question (1)

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Detailed Description

Fio is a flexible I/O tester that simulates arbitrary disk and network workloads without requiring custom test applications.

The tool addresses the problem of repeatedly writing specialized test programs to evaluate I/O performance or reproduce storage-related bugs. Rather than coding a new test harness each time, users define their workload in a job file specifying parameters like thread count, I/O type, and access patterns. Fio then spawns threads or processes to execute that workload, supporting diverse scenarios from memory-mapped file operations to asynchronous I/O across multiple concurrent tasks. Global parameters are inherited by all threads unless explicitly overridden per-thread.

Fio suits anyone benchmarking storage systems, validating I/O scheduler behavior, or stress-testing disk and network subsystems. It is particularly valuable for kernel developers and storage engineers who need to reproduce specific I/O patterns without writing application code. The tool's strength lies in its configurability through job files rather than code changes, making it practical for iterative testing and exploration of different workload characteristics.

The project maintains a substantial user base reporting real-world issues, with almost all open issues originating from outside users rather than the core team. Maintainers typically respond to new issues and pull requests within a day. Work in the issue tracker centers on requests for additional information from reporters, patches welcome for community contributions, and enhancement requests.