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 01:00:00 |
Note -
The number of LWPs swapped out may greater than zero even if the system has an abundance of free memory. This happens when a sleeping LWP is swapped out and has not been awakened (for example, a process or LWP sleeping, waiting for the keyboard or mouse input).
Output from the -q option is described in the table below.
Table 36-15 Output From the sar -q Command|
Field Name |
Description |
|---|---|
|
runq-sz |
The number of kernel threads in memory waiting for a CPU to run. Typically, this value should be less than 2. Consistently higher values mean that the system may be CPU-bound. |
|
%runocc |
The percentage of time the dispatch queues are occupied. |
|
swpq-sz |
The average number of swapped out LWPs. |
|
%swpocc |
The percentage of time LWPs are swapped out. |
Example--Checking Queue Activity
The following abbreviated 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 may be required to obtain acceptable system response.
$ sar -q SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 runq-sz %runocc swpq-sz %swpocc 01:00:00 02:00:02 03:00:00 1.0 0 04:00:00 05:00:01 1.0 0 06:00:00 Average 1.3 0 |
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