xmon - Minimalistic Lightweight System Performance Monitor
by Marc Gloor

Abstract

Xmon is a very puristic, fast and minimalistic lightweight system performance monitor for Linux, purely written in C and linked only against glibc and X11/Xlib. No additional heavyweight window manager bloat included, I kept it lean.

It visualizes real-time system load, memory usage, and CPU activity. The tool operates by reading data directly from the Linux process filesystem (/proc), which must be mounted for the application to function. Read the manpage to learn more about its full functionality.

  * CPU Usage [CPU]: Total processor utilization (central parallel unit usage)
  * Memory [MEM]: Current RAM consumption (used memory)
  * System Load [LOAD]: Standard Linux load average (load average)

Xmon was originally developed in 1998 as a rainy-day educational project to explore low-level Xlib programming in depth. As a result, the early codebase remained in a beta state for many years, largely unoptimized and occasionally prone to bugs. Over time, the most critical early issues were resolved, including memory overflows and the need for periodic graph resets after a fixed number of cycles.

With the release of version 1.0.0 in early 2026, Xmon has undergone a major modernization effort. The codebase has been significantly refactored and enhanced with new features to ensure compatibility with modern Linux kernels and contemporary X11 environments. It has been successfully tested on a recent Debian SID system (February 2026).

While Xmon is not natively portable to other Unix derivatives such as Solaris or AIX, it is designed to run on any hardwar platform supported by a full Linux environment, including architectures such as Sun SPARC and IBM RISC 6000.

The source code is released under the GNU General Public License v3 in the hope that it proves useful to others. If you encounter any bugs or issues, feedback is welcome. Feedback welcome.

Installation

Source package: xmon-1.0.2-src.tar.gz
Download, extract and follow the README instructions to compile and install xmon.

Precompiled binary package: xmon-1.0.2-x86_64-statbin.tar.gz
Download Linux x86-64 ELF (amd64) binary distribution that runs out of the box.

Debian binary package for amd64 architecture: xmon_1.0.2_amd64.deb
Download and install using your package manager e.g. dpkg or apt, in runs out of the box.


Screenshots

xmon in
        action
    xmon on i386    xmon on PPC    


$Id: xmon.html,v 1.36 2026/02/24 09:13:31 gloor Exp $
Author:
marc_dot_gloor_at_u_dot_nus_dot_edu


home