We might have some doubts about OS CPU utilization when we read an AWR report like the following:
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.
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.
|Busy||%BUSY, %BUS, %BU|
|User||%USER, %USR, %US|
|Wait IO||%WIO, %IOWAIT, %WA|