nmon – Nigel’s performance Monitor

Last Updated on August 22, 2023

nmon is short for Nigel’s Performance Monitor. It is a systems administrator, tuner, benchmark tool. It can display the CPU, memory, network, disks (mini graphs or numbers), file systems, NFS, top processes, resources (Linux version & processors) and on Power micro-partition information.

Data is displayed on the screen and updated once every two seconds, using a dumb screen. However, you can easily change this interval to a longer or shorter time period.

The nmon tool can also capture the same data to a text file for later analysis and graphing for reports. The output is in a spreadsheet format (.csv). nmon for Linux was an internal project at IBM for many years and was released to open source under GPL on 27th July 2009.

Features include:

• CPU utilization.
• Memory use.
• Kernel statistics and run queue information.
• Disks I/O rates, transfers, and read/write ratios.
• Free space on file systems.
• Disk adapters.
• Network I/O rates, transfers, and read/write ratios.
• Paging space and paging rates.
• CPU and AIX specification.
• Top processors.
• IBM HTTP Web cache.
• User-defined disk groups.
• Machine details and resources.
• Asynchronous I/O — AIX only.
• Workload Manager (WLM) — AIX only.
• IBM TotalStorage Enterprise Storage Server (ESS) disks — AIX only.
• Network File System (NFS).
• Dynamic LPAR (DLPAR) changes.

Website: nmon.sourceforge.net
Support: Documentation
Developer: Nigel Griffiths
License: GNU GPL v2

nmon is written in C. Learn C with our recommended free books and free tutorials.

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