bitesize.bt(8)

📦 version 0.17.0, in debian bookworm

💅 bitesize.bt — the disk I/O size histogram bestie

okay so this is bitesize.bt, a little tool from the System Manager's Manual (section 8, we love a sysadmin moment), and it shows your disk I/O sizes as a histogram. yes. a whole vibe chart for your block device. uses bpftrace/eBPF, obviously. 🦋

✨ NAME ✨

bitesize.bt — show disk I/O size as a histogram. uses bpftrace/eBPF. no cap.

🌸 SYNOPSIS 🌸

bitesize.bt

that's it. that's the whole thing. no flags, no args, just run it and let it cook. 💅

💖 DESCRIPTION 💖

so like, you can use this to characterize the distribution of block device (disk) I/O sizes. if you wanna study block device I/O in more detail (main character behaviour), go look at biosnoop.bt(8) instead, she's right there in SEE ALSO. 🎀

this tool uses the tracepoint:block:block_rq_issue tracepoint, and honestly it's just a simple little example of bpftrace. a starter pack, if you will. ✨

since this uses BPF, only the root user can use this tool. periodt. root or nothing, bestie. 👑

🧚 REQUIREMENTS 🧚

  • CONFIG_BPF
  • bpftrace

you need both. no skipping. 🙈

🔥 EXAMPLES 🔥

trace block I/O and summarize as a histogram by process:

# bitesize.bt

one line. iconic. 🌈

🎀 FIELDS 🎀

okay so the output has columns and here's what each one is giving:

  • 0th — a process name (shown in "@[...]") is printed before each I/O histogram. so you know who is being noisy. 💅
  • 1st, 2nd — this is a range of I/O sizes, in Kbytes (shown in "[...)" set notation). maths notation but make it cute.
  • 3rd — a column showing the count of I/O in this range. how many times did this size show up. 🔢
  • 4th — this is an ASCII histogram representing the count column. bars!! in your terminal!! 🍓

💜 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. we're chillin. 😌

but fr fr, for high IOPS storage systems, test and quantify before use. don't just yolo it on prod, bestie. 💀

⭐ SOURCE ⭐

this is from bpftrace.

https://github.com/iovisor/bpftrace

also, look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool. it's like the director's commentary track but for a script. 🎬

this is a bpftrace version of the bcc tool of the same name. twin sisters, different ecosystems. 🫶

https://github.com/iovisor/bcc

🌸 OS 🌸

Linux. as always. 🐧

💅 STABILITY 💅

Unstable - in development.

she's still growing, okay?? give her time. it's giving wip. 🦋

👑 AUTHOR 👑

Brendan Gregg

the legend herself/himself. we stan. 🙌

🌈 SEE ALSO 🌈

go read that one next, bestie, iykyk. 💖

and that's the whole page!! this was the USER COMMANDS manual, dated 2018-09-07, and it's literally called bitesize.bt(8) — remember the name, she's iconic. mwah, bye!! 💋✨

📦 where this page comes from