How to Check Queue Activity (sar -q)

1. Use the sar -q command to report the following information:

   • The Average queue length while the queue is occupied.

   • The percentage of time that the queue is occupied.

   $ sar -q 00:00:00 runq-sz %runocc swpq-sz %swpocc

   The following list describes the output from the -q option.

   runq-sz

   The number of kernel threads in memory that are waiting for a CPU to run. Typically, this value should be less than 2. Consistently higher values mean that the system might be CPU-bound.

   %runocc

   The percentage of time that the dispatch queues are occupied.

   swpq-sz

   No longer reported by the sar command.

   %swpocc

   No longer reported by the sar command.

Example 13–12 Checking Queue Activity

The following example shows output from the sar -q command. If the %runocc value is high (greater than 90 percent) and the runq-sz value is greater than 2, the CPU is heavily loaded and response is degraded. In this case, additional CPU capacity might be required to obtain acceptable system response.

$ sar -q

SunOS balmyday 5.10 s10_51 sun4u    03/18/2004

00:00:04 runq-sz %runocc swpq-sz %swpocc
01:00:00     1.0       0     0.0       0
02:00:01     1.3       0     0.0       0
03:00:00     1.0       0     0.0       0
04:00:00     1.0       0     0.0       0
05:00:00     1.0       0     0.0       0
06:00:00     2.0       0     0.0       0
07:00:00     0.0       0     0.0       0
08:00:00     1.0       0     0.0       0
08:20:00     1.0       0     0.0       0
08:40:01     2.0       0     0.0       0
09:00:00     0.0       0     0.0       0
09:20:00     1.0       0     0.0       0
09:40:00     1.2       2     0.0       0
10:00:00     1.2       2     0.0       0
10:20:00     1.0       1     0.0       0
10:40:00     1.3       9     0.0       0
11:00:00     1.2       7     0.0       0

Average      1.2       1     0.0       0