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 |
Note –
The number of LWPs swapped out might be greater than zero even if the system has an abundance of free memory. This situation happens when a sleeping LWP is swapped out and has not been awakened (for example, a process or LWP is sleeping, waiting for keyboard or mouse input).
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 |
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 might be required to obtain acceptable system response.
$ sar -q SunOS venus 5.9 Generic sun4u 06/24/2001 08:45:18 runq-sz %runocc swpq-sz %swpocc 08:45:18 unix restarts 09:00:00 1.0 0 0.0 0 09:20:00 0.0 0 0.0 0 09:40:00 0.0 0 0.0 0 Average 1.0 0 0.0 0 |
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