nfsdist(8)

💖 nfsdist(8) 💖

System Manager's Manual ✨ okay so this is the page for nfsdist, a tool that tells you how long NFS file operations take 🧚

✨ NAME ✨

nfsdist is the tool, and it's here to summarize NFS operation latency 💅 It runs on Linux and uses eBPF/bcc 🔥

✨ SYNOPSIS ✨

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

🎀 DESCRIPTION 🎀

okay so bestie, nfsdist measures how much time gets eaten up by the common NFS file operations: reads, writes, opens, and getattrs 🦋 It shows all of that as a power-of-2 histogram, and it keeps the histogram in an in-kernel eBPF map so it doesn't wreck your performance 💜

It works by tracing the nfs_file_operations interface functions, so if those functions ever change, this tool will need an update too 🙈

⚠️ Only the root user can run this, because it uses BPF. Not me trying to sneak in as a regular user 💀

🌸 REQUIREMENTS 🌸

You need CONFIG_BPF and bcc 🍓

🫶 OPTIONS 🫶

• -h — pulls up the usage message 🌈
• -T — skips the timestamps on the interval output ⭐
• -m — shows the output in milliseconds instead of microseconds 🎀
• -p PID — only traces the process with this PID, so it's giving focus 👑

💅 EXAMPLES 💅

Trace NFS operation time, and print a summary when you hit Ctrl-C:

# nfsdist

Trace PID 181 only:

# nfsdist -p 181

Print 1 second summaries, 10 times:

# nfsdist 1 10

1 second summaries, printed in milliseconds:

# nfsdist -m 1

🦋 FIELDS 🦋

• msecs — the range of milliseconds this bucket covers 🌸
• usecs — the range of microseconds this bucket covers 🌸
• count — how many operations landed in that time range 💖
• distribution — an ASCII picture of the distribution, drawn from the count column 📊

😭 OVERHEAD 😭

nfsdist adds low-overhead instrumentation to these NFS operations, and that includes reads and writes coming 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 tool's overhead can start to show up 🥺 Measure and quantify before you use it, bestie 🧐

🧚 SOURCE 🧚

This comes from bcc 💜

https://github.com/iovisor/bcc

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

🌈 OS 🌈

Linux 🐧

🙈 STABILITY 🙈

Unstable, since it's still in development 🚧

👑 AUTHOR 👑

Samuel Nair 🫶

✨ SEE ALSO ✨

nfsslower(8) is the one to check out next 🔥

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That's the whole page, babe! 🌈 Pulled from the USER COMMANDS section, dated 2017-09-08, and it's giving nfsdist(8) all the way 💖✨