bitesize.bt(8) System Manager's Manual bitesize.bt(8)

# [NAME](#NAME)

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

# [SYNOPSIS](#SYNOPSIS)

**bitesize.bt**

# [DESCRIPTION](#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)](/man/enterprise-packages/bpftrace/biosnoop.bt.8).

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](#REQUIREMENTS)

CONFIG\_BPF and bpftrace.

# [EXAMPLES](#EXAMPLES)

[Trace block I/O and summarize as a histogram by process:](#Trace)

\# **bitesize.bt**

# [FIELDS](#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](#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](#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](#OS)

Linux

# [STABILITY](#STABILITY)

Unstable - in development.

# [AUTHOR](#AUTHOR)

Brendan Gregg

# [SEE ALSO](#SEE_ALSO)

[biosnoop.bt(8)](/man/enterprise-packages/bpftrace/biosnoop.bt.8)

2018-09-07 USER COMMANDS

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Document: bitesize.bt(8) from bpftrace 0.27.1-r0 (Chainguard OS)
Source: https://github.com/bpftrace/bpftrace