How to Read CPU Utilization of OS Statistics in AWR

CPU Utilization Breakdown

CPU Utilization

We might have some doubts about OS CPU utilization when we read an AWR report like the following:

CPU Utilization Statistics - from AWR

CPU Utilization Statistics - from AWR

We all may be confused among these components, which are %BUSY, %USER, %SYS, %IOWAIT and %IDLE. To figure them out, we need to know their relationships.

Breakdown Structure

Here is a breakdown structure of CPU utilization components that could help us to read and understand OS statistics more easily.

  • 100 % = %BUSY + %IDLE
  • %BUSY = %USER + %SYSTEM
  • %IDIL = %WIO + (UNDEFINED)

In different OS, the names of these components could vary.

NameAliases
Busy%BUSY, %BUS, %BU
User%USER, %USR, %US
System%SYS, %SY
Wait IO%WIO, %IOWAIT, %WA
Idle%IDLE, %ID