---
name: "biostacks.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/biostacks.bt"
---

# biostacks.bt(8)

Show disk I/O latency with initialization stacks. Uses bpftrace/eBPF.

## NAME

biostacks - Show disk I/O latency with initialization stacks. Uses bpftrace/eBPF.

## SYNOPSIS

**biostacks**

## DESCRIPTION

This tool shows disk I/O latency histograms for each block I/O initialization path. This can help reveal the reason for different latencies, as some may be created by log flushing, others by application reads, etc.

This works by attaching to block\_io\_start and block\_rq\_issue tracepoints.

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

## REQUIREMENTS

CONFIG\_BPF and bpftrace.

## EXAMPLES

- Trace disk I/O latency with initialization stacks:

  \# **biostacks.bt**

## FIELDS

- 0th

  An initialization kernel stack trace (shown in "@\[...\]") is printed before each I/O histogram.

- 1st, 2nd

  This is a range of I/O latency, in microseconds (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

The rate of biostacks should be low (bounded by device IOPS), such that the overhead of this tool is expected to be negligible.

## SOURCE

This tool originated from the book "BPF Performance Tools", published by Addison Wesley (2019):

-

  http://www.brendangregg.com/bpf-performance-tools-book.html

See the book for more documentation on this tool.

This version is in the bpftrace repository:

-

  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.

## OS

Linux

## STABILITY

Unstable - in development.

## AUTHOR

Brendan Gregg

## SEE ALSO

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