biotop(8)

💅 biotop(8) — System Manager's Manual energy 💅

okay bestie, this is biotop(8) from the System Manager's Manual, and it is literally here to show you disk I/O by process. Group-chat top, but for block devices. 🫶

🌸 NAME 🌸

biotop — Block device (disk) I/O by process top.

✨ SYNOPSIS ✨

biotop [-h] [-C] [-r MAXROWS] [-p PID] [interval] [count]

Yep, -h is right there in the synopsis, and the original OPTIONS list below sticks to what it spells out. No invented lore, bestie. 💖

🌈 DESCRIPTION 🌈

This is top for disks. No cap.

It traces block device I/O (disk I/O) and prints a per-process summary every interval — by default, 1 second. The summary is sorted on the top disk consumers by throughput (Kbytes). The PID and process name shown are measured from when the I/O was first created, which usually identifies the responsible process.

For efficiency, this uses in-kernel eBPF maps to cache process details (PID and comm) by I/O request, as well as a starting timestamp for calculating I/O latency, and the final summary.

It works by tracing various kernel blk_*() functions using dynamic tracing, and it will need updating to match any changes to these functions.

⚠️ Since this uses BPF, only the root user can use this tool. That part is not a vibe check — it's a requirement.

🎀 REQUIREMENTS 🎀

CONFIG_BPF and bcc. That's the whole list. ✨

💅 OPTIONS 💅

• -C — Don't clear the screen. Your screen stays exactly where it is, bestie.
• -r MAXROWS — Maximum number of rows to print. Default is 20.
• -p PID — Trace this PID only.
• interval — Interval between updates, seconds.
• count — Number of interval summaries.

🦋 EXAMPLES 🦋

Summarize block device I/O by process, 1 second screen refresh:

# biotop

Don't clear the screen:

# biotop -C

5 second summaries, 10 times only:

# biotop 5 10

🌸 FIELDS 🌸

• loadavg — The contents of /proc/loadavg.
• PID — Cached process ID, if present. This usually, but isn't guaranteed, identifies the responsible process for the I/O.
• COMM — Cached process name, if present. This usually, but isn't guaranteed, identifies the responsible process for the I/O.
• D — Direction: R == read, W == write. This is a simplification.
• MAJ — Major device number.
• MIN — Minor device number.
• DISK — Disk device name.
• I/O — Number of I/O during the interval.
• Kbytes — Total Kbytes for these I/O, during the interval.
• AVGms — Average time for the I/O (latency) from the issue to the device, to its completion, in milliseconds.

🔥 OVERHEAD 🔥

Since block device I/O usually has a relatively low frequency (< 10,000/s), the overhead for this tool is expected to be low or negligible. For high IOPS storage systems, test and quantify before use. That's the responsible main-character move. 👑

🧚 SOURCE 🧚

This is from bcc.

https://github.com/iovisor/bcc

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

⭐ OS ⭐

Linux.

🌈 STABILITY 🌈

Unstable - in development. She's still cooking, bestie. 🍓

💖 AUTHOR 💖

Brendan Gregg, Rocky Xing.

🎀 INSPIRATION 🎀

top(1) by William LeFebvre.

🫶 SEE ALSO 🫶

• biosnoop(8)
• biolatency(8)
• iostat(1)

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Cute sign-off: this page is filed under USER COMMANDS, dated 2016-02-06, and it's the biotop(8) page from bcc. Periodt. 💅✨