xfsdist.bt(8)

📦
version 0.27.0 · 3 versions
  • 0.27.0 · alpine 3.24, arch rolling, centos-stream 10, centos-stream 9, debian trixie, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable, opensuse-leap 16.0, ubuntu questing, ubuntu resolute, ubuntu stonking (latest)
  • 0.14.0 · ubuntu jammy
  • 0.20.2 · ubuntu noble
, in alpine 3.24, arch rolling, centos-stream 10, centos-stream 9, debian trixie, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable, opensuse-leap 16.0, ubuntu questing, ubuntu resolute, ubuntu stonking

✨ xfsdist.bt(8) — the XFS latency tea ✨

Hey bestie, this is the manual page for xfsdist.bt (manual name: xfsdist.bt, section 8) 🎀 Let me spill it!

💖 NAME

xfsdist.bt — Summarize XFS operation latency. Uses bpftrace/eBPF. ✨

🧚 SYNOPSIS

xfsdist.bt

🌸 DESCRIPTION

okay so this tool summarizes the time (aka latency) spent in common XFS file operations: reads, writes, opens, and syncs 📖 and it shows you all of it as a power-of-2 histogram 📊 It uses an in-kernel eBPF map to store the histogram, which is lowkey so efficient 💅

Since this works by tracing the xfs_file_operations interface functions, it will need updating to match any changes to those functions. Not me being dramatic, it's just the truth 🙈

Since this uses BPF, only the root user can use this tool 🔥 no cap.

🎀 REQUIREMENTS

You need CONFIG_BPF and bpftrace. That's the whole list, periodt ✨

🦋 EXAMPLES

Trace XFS operation time, and print a summary on Ctrl-C:

# xfsdist.bt

📊 FIELDS

  • 0th — The operation name (shown in "@[...]") gets printed before each I/O histogram 💜
  • 1st, 2nd — This is a range of latency, in microseconds (shown in "[...)" set notation) 🍓
  • 3rd — A column showing the count of operations in this range 💅
  • 4th — This is an ASCII histogram representing the count column ✨

⚠️ OVERHEAD

Heads up bestie: this adds low-overhead instrumentation to these XFS operations, including reads and writes from the file system cache. Those reads and writes can be super frequent (it depends on the workload, eg, 1M/sec), and at that point the overhead of this tool may become noticeable 😭 Measure and quantify before use.

🌈 SOURCE

This is from bpftrace.

https://github.com/bpftrace/bpftrace

Also look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool 🧚

This is a bpftrace version of the bcc tool of the same name. The bcc tool may provide more options and customizations 🫶

https://github.com/iovisor/bcc

💻 OS

Linux 🐧

🧪 STABILITY

Unstable — still in development 🙈

👑 AUTHOR

Brendan Gregg 💖

🔗 SEE ALSO

Bye bestie, that's the whole tea from xfsdist.bt(8), straight from the USER COMMANDS section, dated 2018-09-08 🌸💅

📦 where this page comes from