---
name: "biotop-bpfcc"
section: "8"
platform: "linux"
package: "bpfcc-tools"
version: "0.31.0+ds-7"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/biotop-bpfcc"
---

# biotop-bpfcc(8)

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

## NAME

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

## SYNOPSIS

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

## DESCRIPTION

This is top for disks.

This 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.

This works by tracing various kernel blk\_\*() functions using dynamic tracing, and will need updating to match any changes to these functions.

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

## REQUIREMENTS

CONFIG\_BPF and bcc.

## OPTIONS

- \-C

  Don't clear the screen.

- \-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) to identify the responsible process for the I/O.

- COMM

  Cached process name, if present. This usually (but isn't guaranteed) to identify 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.

## 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.

## OS

Linux

## STABILITY

Unstable - in development.

## AUTHOR

Brendan Gregg, Rocky Xing

## INSPIRATION

[top(1)](/top/1.md) by William LeFebvre

## SEE ALSO

biosnoop(8), biolatency(8), [iostat(1)](/iostat/1.md)