How to Check Queue Activity (sar -q)
Use the sar -q command to report the average queue length while the queue is occupied, and the percentage of time that the queue is occupied.
$ sar -q 00:00:00 runq-sz %runocc swpq-sz %swpocc |
The following table describes the output from the -q option.
Table 24–15 Output From the sar -q Command|
Field Name |
Description |
|---|---|
|
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 sar. |
|
%swpocc |
No longer reported by sar. |
Example—Checking Queue Activity
The following example shows output from the sar -q command. If %runocc is high (greater than 90 percent) and runq-sz 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 touchstone 5.9 Generic sun4u 03/04/2003 00:00:00 runq-sz %runocc swpq-sz %swpocc 01:00:00 0.0 0 0.0 0 02:00:00 0.0 0 0.0 0 03:00:00 0.0 0 0.0 0 04:00:00 1.0 0 0.0 0 05:00:00 0.0 0 0.0 0 06:00:00 0.0 0 0.0 0 07:00:00 1.0 0 0.0 0 08:00:00 0.0 0 0.0 0 08:20:01 0.0 0 0.0 0 08:40:00 0.0 0 0.0 0 09:00:00 1.0 0 0.0 0 09:20:01 1.6 3 0.0 0 09:40:01 1.5 8 0.0 0 10:00:02 1.6 7 0.0 0 10:20:03 1.5 2 0.0 0 10:40:01 1.9 1 0.0 0 11:00:01 1.4 0 0.0 0 11:20:01 1.6 0 0.0 0 Average 1.6 1 0.0 0 |
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