xfsdist(8)

✨ xfsdist(8) ✨

System Manager's Manual, but make it cute 🎀

💖 NAME 💖

xfsdist - Summarize XFS operation latency. Uses Linux eBPF/bcc. 🦋

🧚 SYNOPSIS 🧚

xfsdist [-h] [-T] [-m] [-p PID] [interval] [count]

🌸 DESCRIPTION 🌸

okay so this tool measures how long common XFS file operations take 😭 bestie, we're talking reads, writes, opens, and syncs. It shows the results as a power-of-2 histogram 📊 and it stores that histogram in an in-kernel eBPF map, which keeps things efficient ✨

Heads up: this works by tracing the xfs_file_operations interface functions, so it's going to need updating if those functions ever change 🙈

⚠️ Since this uses BPF, only the root user can run this tool. Sorry, not sorry 💅

🎀 REQUIREMENTS 🎀

You'll need CONFIG_BPF and bcc. No cap, nothing else 💜

💅 OPTIONS 💅

• -h — Pulls up the usage message 📖
• -T — Skips the timestamps on interval output 🕰️
• -m — Shows the output in milliseconds instead of microseconds 🍓
• -p PID — Only traces this PID, main character energy 👑

🦋 EXAMPLES 🦋

Trace XFS operation time, then get a summary when you hit Ctrl-C 💫:

# xfsdist

Trace PID 181 only 🎯:

# xfsdist -p 181

Print 1 second summaries, 10 times 🔥:

# xfsdist 1 10

1 second summaries, printed in milliseconds 🌈:

# xfsdist -m 1

📊 FIELDS 📊

• msecs — The range of milliseconds for this bucket ⏱️
• usecs — The range of microseconds for this bucket ⚡
• count — How many operations landed in this time range 🔢
• distribution — An ASCII picture of the distribution, based on the count column 🎨

💀 OVERHEAD 💀

ngl, this adds low-overhead instrumentation to these XFS operations, and that includes reads and writes served from the file system cache 🥺 Those reads and writes can be super frequent depending on the workload (like 1M/sec), and at that point the overhead of this tool can start to show up 😬 Measure and quantify before use so you're not caught off guard 🫶

🌷 SOURCE 🌷

This comes from bcc 💜

https://github.com/iovisor/bcc

Also check out the bcc distribution for a companion _examples.txt file, which has example usage, output, and commentary for this tool 📚

🌈 OS 🌈

Linux 🐧

🧪 STABILITY 🧪

Unstable, still in development 🚧

👩‍💻 AUTHOR 👩‍💻

Brendan Gregg 👑

🔗 SEE ALSO 🔗

• xfssnoop(8) ✨

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Bestie, that's the whole page 💖 Source is bcc, the manual lives under USER COMMANDS, and it was dated 2016-02-12, so go be iconic with your XFS latency data 🦋✨