CPU usage explained

Category: Linux
Created: 2021-08-26

In the server management page of LiveConfig you can see a graph of your CPU usage:

But what do these values mean?

User

The CPU is running “normal” user-mode code (any application, no matter whether begin run as root or as normal user).

System

The CPU is running system/kernel code (for example kernel modules or drivers).

nice

Nearly the same as User mode, but the respective application code is run with lower priority.

wait

If the system needs to read or write data (network, disk, USB stick, whatever…) the CPU is put to “sleep” (regardless if running user or system code) and waits until the I/O operation has finished.

Steal

If your server is virtualized, the host system may “steal” CPU cycles from your instance and assign them to another instance. A high value for “steal” can indicate an overbooking/overloading of the host system.

Guest

A hypervisor is running a virtual CPU.

IRQ

The CPU is running interrupt handler code. Usually you won’t see this appearing.