---
name: "bitesize.bt"
section: "8"
platform: "linux"
package: "bpftrace"
version: "0.27.0-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/bitesize.bt"
---

# bitesize.bt(8)

Show disk I/O size as a histogram. Uses bpftrace/eBPF.

## NAME

bitesize.bt - Show disk I/O size as a histogram. Uses bpftrace/eBPF.

## SYNOPSIS

**bitesize.bt**

## DESCRIPTION

This can be used to characterize the distribution of block device (disk) I/O sizes. To study block device I/O in more detail, see [biosnoop.bt(8)](/biosnoop.bt/8.md).

This uses the tracepoint:block:block\_rq\_issue tracepoint, and is a simple example of bpftrace.

Since this uses BPF, only the root user can use this tool.

## REQUIREMENTS

CONFIG\_BPF and bpftrace.

## EXAMPLES

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

  \# **bitesize.bt**

## FIELDS

- 0th

  A process name (shown in "@\[...\]") is printed before each I/O histogram.

- 1st, 2nd

  This is a range of I/O sizes, in Kbytes (shown in "\[...)" set notation).

- 3rd

  A column showing the count of I/O in this range.

- 4th

  This is an ASCII histogram representing the count column.

## 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.

## SOURCE

This is from bpftrace.

-

  https://github.com/bpftrace/bpftrace

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

This is a bpftrace version of the bcc tool of the same name.

-

  https://github.com/iovisor/bcc

## OS

Linux

## STABILITY

Unstable - in development.

## AUTHOR

Brendan Gregg

## SEE ALSO

[biosnoop.bt(8)](/biosnoop.bt/8.md)