System Administration Guide, Volume 2

How to Check CPU Utilization (sar -u)

Display CPU utilization with the sar -u command.


$ sar -u
00:00:00    %usr    %sys    %wio   %idle
01:00:00       0       0       0     100

(The sar command without any options is equivalent to sar -u.) At any given moment, the processor is either busy or idle. When busy, the processor is in either user or system mode. When idle, the processor is either waiting for I/O completion or "sitting still" with no work to do.

Output from the -u option is described in the table below.

Table 36-17 Output From the sar -u Command

Field Name 

Description 

%sys

Lists the percentage of time that the processor is in system mode 

%user

Lists the percentage of time that the processor is in user mode 

%wio

Lists the percentage of time the processor is idle and waiting for I/O completion 

%idle

Lists the percentage of time the processor is idle and is not waiting for I/O 

A high %wio generally means a disk slowdown has occurred.

Example--Checking CPU Utilization

The following example shows output from the sar -u command.


$ sar -u
SunOS venus 5.8 Generic sun4u    09/07/99

00:00:00    %usr    %sys    %wio   %idle
01:00:00       0       0       0     100
02:00:02       0       0       0     100
03:00:00       0       0       0     100
04:00:00       0       0       0     100
05:00:01       0       0       0     100
06:00:00       0       0       0     100
07:00:00       0       0       0     100
08:00:01       0       0       0     100
08:20:00       0       0       0     100
08:40:00       0       0       0     100
09:00:00       0       0       0     100
09:20:00       0       0       0     100
09:40:00       0       0       0     100
10:00:00       0       0       0     100
10:20:00       0       0       0     100
10:40:01       0       0       0     100
11:00:00       5       2      10      82

Average        0       0       0     100