iotop - Rust Implementation

A modern, high-performance Rust implementation of iotop - a tool to monitor I/O usage of processes on Linux.

Snapshot

Installation

From Cargo (Recommended)

Install directly from crates.io:

cargo install iotop

From Source

Clone and build from source:

git clone https://github.com/AndPuQing/iotop.git
cd iotop
cargo build --release

The binary will be available at ./target/release/iotop.

System-wide Installation

Option 1: Copy binary to system path

cargo build --release
sudo cp target/release/iotop /usr/local/bin/
sudo cp doc/iotop.8 /usr/share/man/man8/
sudo mandb  # Update man page database

Option 2: Using cargo install with prefix

cargo install --path . --root /usr/local
sudo cp doc/iotop.8 /usr/share/man/man8/
sudo mandb

Permissions Setup

iotop requires root privileges to access the kernel's taskstats interface. You have two options:

Option 1: Run with sudo (simplest)

sudo iotop

Option 2: Grant CAP_NET_ADMIN capability (no sudo needed)

# Allow iotop to run without sudo by granting the required capability
sudo setcap cap_net_admin+eip /usr/local/bin/iotop

# Now you can run without sudo
iotop

Enable Kernel Delay Accounting

For full functionality (SWAPIN and IO columns), enable kernel delay accounting:

# Temporary (until reboot)
sudo sysctl -w kernel.task_delayacct=1

# Permanent (survives reboot)
echo "kernel.task_delayacct = 1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

Usage

Basic Examples

Run interactively:

sudo iotop

Show only processes doing I/O:

sudo iotop -o

Run in batch mode (5 iterations, 2 second delay):

sudo iotop -b -n 5 -d 2

Monitor specific process:

sudo iotop -p 1234

Monitor user's processes:

sudo iotop -u www-data

Filter by command-line regex:

sudo iotop -c bash
sudo iotop -c '^sshd' -c 'nginx.*worker'

Batch mode with timestamps:

sudo iotop -t -b -n 10 > iotop.log

Machine-readable output for scripts / monitoring (JSON and CSV both imply --batch):

One JSON object per iteration, with the total/actual disk I/O and the process list:

sudo iotop -b --json -n 1

CSV rows (header printed unless -q; add a leading time column with -t):

sudo iotop -b --csv -n 5
sudo iotop -b --csv -t -q -n 5

Command-Line Options

Option	Long Form	Description
-o	--only	Only show processes or threads actually doing I/O
-P	--processes	Show processes instead of all threads
-a	--accumulated	Show accumulated I/O instead of bandwidth
-d	--delay	Delay between iterations in seconds [default: 1.0]
-n	--iterations	Number of iterations before ending (infinite if not specified)
-b	--batch	Batch mode (non-interactive)
-p	--pid	Monitor specific processes/threads (can be repeated)
-u	--user	Monitor processes by username or UID (can be repeated)
-c	--command	Only show processes whose command line matches the regex (can be repeated)
-t	--time	Add timestamp on each line (implies --batch)
-q	--quiet	Suppress column names and headers (implies --batch)
-k	--kilobytes	Use kilobytes instead of human-friendly units
	--json	Output one JSON object per iteration (implies --batch)
	--csv	Output CSV rows (implies --batch)

Interactive Mode Controls

When running in interactive mode (default), you can use the following keyboard shortcuts:

Key	Action
q / Q / Ctrl+C	Quit the program
o / O	Toggle showing only processes doing I/O
a / A	Toggle between bandwidth and accumulated I/O
p / P	Toggle between showing processes and threads
r / R	Reverse the current sort order
k / K	Toggle KB units (also enabled by -k at startup)
c / C	Enter/exit column-selection mode (see below)
Space	Pause/resume display updates (toggle column in column mode)
Left / Right	Cycle through sort columns (move cursor in column mode)
Up / Down	Scroll through process list
PageUp / PageDown	Scroll by 10 rows
Home	Jump to first sort column (or first row with Ctrl)
End	Jump to last sort column (or last row with Ctrl)

Mouse wheel scrolling is also supported for navigating the process list.

Column Selection Mode

Press c to enter column-selection mode. The top bar shows every available column; Left / Right move the cursor, Space toggles the selected column on/off, and Esc or c exits. Hidden columns are shown dimmed with ~ markers. The last remaining visible column cannot be hidden.

Architecture

This implementation uses:

• Netlink Taskstats: Interfaces with the Linux kernel's taskstats interface via netlink sockets
• Procfs: Reads process information from /proc filesystem
• Async/Await: Tokio-based async runtime for concurrent data collection
• TUI Framework: Crossterm + Ratatui for terminal rendering

Development

Run the project in development mode:

# Build and run
cargo run -- [options]

# Build in release mode
cargo build --release

# Run tests
cargo test

# Check for issues
cargo clippy

# Format code
cargo fmt

# Run with custom options
cargo run -- -o -d 2

License

MIT License - See LICENSE file for details.

References

• Original Python implementation: http://guichaz.free.fr/iotop/
• C version by Tomas M: https://github.com/Tomas-M/iotop
• Linux Taskstats documentation: https://www.kernel.org/doc/Documentation/accounting/taskstats.txt

Contributing

Contributions are welcome! This is an ongoing migration project. Areas for contribution include:

• Additional test coverage
• Performance optimizations
• Documentation improvements
• Bug fixes and feature requests

Please open an issue or pull request on GitHub.