vfscount.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

🎀 vfscount.bt(8) 🎀

System Manager's Manual 💅

✨ NAME ✨

vfscount.bt — okay so this one counts VFS calls (anything named "vfs_*") 🔥 It runs on bpftrace/eBPF 💖

🌸 SYNOPSIS 🌸

vfscount.bt

💭 DESCRIPTION 💭

okay so this tool counts VFS calls, and it's giving super useful vibes for general workload characterization of these operations 🧚

how it works: it traces every kernel function that starts with "vfs_" using dynamic tracing ✨ heads up, this might catch more functions than you actually care about 🙈 so if that's you, just edit the script and customize which functions get traced. no judgment 🫶

⚠️ bestie, this one uses BPF, so only the root user can run it. sorry not sorry 💀

📋 REQUIREMENTS 📋

you'll need CONFIG_BPF and bpftrace 🎀

🦋 EXAMPLES 🦋

Count all VFS calls until you hit Ctrl-C:

# vfscount.bt

🍓 FIELDS 🍓

  • 1st — the kernel function name (shows up in @[]) 💜
  • 2nd — the number of calls while tracing 🌈

🔥 OVERHEAD 🔥

ngl this is lowkey iconic: it traces kernel vfs functions and keeps the counts in-kernel, then asynchronously copies them over to user-space 🧠 the VFS rate can get wild (like >1M/sec), but this is a relatively efficient way to trace these events, so the overhead should be small for normal workloads ✨

still, measure in a test environment first 💅 and if the overhead is an issue, edit the script to trace fewer vfs functions (right now it's all of the ones beginning with "vfs_") 🫶

🌍 SOURCE 🌍

this is from bpftrace 🧚

https://github.com/bpftrace/bpftrace

also check the bpftrace distribution for a companion _examples.txt file. it has example usage, output, and commentary for this tool 📚

this is the bpftrace version of the bcc tool with the same name. the bcc tool might give you more options and customizations 💖

https://github.com/iovisor/bcc

💻 OS 💻

Linux 🐧

🚧 STABILITY 🚧

Unstable — still in development, so be a little careful 🙈

👑 AUTHOR 👑

Brendan Gregg 🌟

🦋 SEE ALSO 🦋

vfsstat.bt(8) 💜

bestie, that's the whole page! ✨ bpftrace source, version and date: USER COMMANDS, 2018-09-06 🎀 stay curious and keep those VFS calls counted 💖🫶

📦 where this page comes from