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

   Swap queue of processes for the sar command.

   %swpocc

   Swap queue of processes for 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 system2 5.10 Generic_142909-13 sun4u    06/28/2010

00:00:00 runq-sz %runocc swpq-sz %swpocc
01:00:00     1.0       7     0.0       0
02:00:00     1.0       7     0.0       0
03:00:00     1.0       7     0.0       0
04:00:00     1.0       7     0.0       0
05:00:00     1.0       6     0.0       0
06:00:00     1.0       7     0.0       0

Average      1.0       7     0.0       0