Linux htop/top Display Items Fully Explained (2019)
Original: Explanation of everything you can see in htop/top on Linux (2019)
Why This Matters
Deep /proc-level Linux process monitoring knowledge is essential for SRE, DevOps, and systems engineers.
Peteris Rocks published a comprehensive guide explaining every element visible in htop and top on Linux, covering uptime, load average, process states, memory metrics (VIRT/RES/SHR), PID, niceness, and more, sourced directly from /proc filesystem internals.
This 2019 blog post by Peteris Rocks became a top post on Hacker News twice (December 2016 and November 2019) and topped r/programming and r/sysadmin, indicating strong community interest. The article systematically explains every field shown in htop on Ubuntu Server 16.04 x64.
Key topics covered include: Uptime (read from /proc/uptime), Load Average (1/5/15-minute averages from /proc/loadavg — clarifying that 1.0 on a dual-core machine does not mean 50% CPU usage), Process States (R=running, S=interruptible sleep, D=uninterruptible sleep, Z=zombie, T=stopped), Memory fields (VIRT/VSZ for virtual image, RES/RSS for resident memory, SHR for shared memory, MEM%), and process niceness/priority.
The author uses strace to trace which /proc files system utilities like uptime actually read, providing a low-level, source-backed methodology. The guide also covers file descriptors, shell redirection, PID trees, and process ownership, making it a practical reference for Linux system administrators and developers.