CPU Utilization Breakdown
We might have some doubts about OS CPU utilization when we read an AWR report like the following:
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.
| Name | Aliases |
|---|---|
| Busy | %BUSY, %BUS, %BU |
| User | %USER, %USR, %US |
| System | %SYS, %SY |
| Wait IO | %WIO, %IOWAIT, %WA |
| Idle | %IDLE, %ID |