Computer Hardware Essentials - CPU, Memory, and Virtualization

Linux exposes hardware as files and small commands. An administrator who cannot count processors or read a memory total cannot size a host, escalate a ticket, or tell a virtual machine from a container. nproc, lscpu, and /proc/cpuinfo are three views of the same kernel data. free is a formatted view of /proc/meminfo. systemd-detect-virt --vm asks whether this kernel is running as a hardware virtual machine, which is a different question from whether the current process is in a container.

The SKU on a label (2 vCPU / 8 GB) and the numbers /proc reports are not the same. Firmware and the hypervisor hold back a slice, so an 8 GB guest often reports a little under 8000 MiB. The free column and the available column are also not the same: unused RAM versus memory the kernel believes it can give to a new workload.

In this lab, you will count processors three ways, measure memory with free and /proc/meminfo, and record whose hardware this is with systemd-detect-virt --vm.

Objectives

By completing this beginner lab, you will be able to:

• Count processors with nproc, lscpu, and /proc/cpuinfo, then record the live nproc value
• Read free -h, free -m, free -b, and /proc/meminfo, account for the advertised-versus-reported gap, and distinguish free from available
• Identify hardware virtualization with systemd-detect-virt --vm and the lscpu virt line, then re-read the CPU model with that context

Who is this lab for?

This lab is designed for:

• Helpdesk and junior sysadmin students who need to read the box they are on before they size or escalate anything
• Linux beginners who can open a terminal and want to inspect CPU, memory, and virtualization on a live host