Performance AIX

[saythere]

Do anybody know what does "high run queue and low CPU" mean ? I have a computer with AIX 4.3, 12 processors that average run queue processes = 4 (per processor) but %CPU (average too) = 34% ... How can I investigate the reason ?


Thanks.

Fatima

 

[saythere]

Do someone know what does "high run queue and low CPU" mean ? I have a computer with AIX 4.3, 12 processors that average run queue processes = 4 (per processor) but %CPU (average too) = 34% ... How can I investigate the reason ?

 

[ademeter]

Hi,
attach a "vmstat 1 5" and "sar -P ALL 1 5" output. The runqueue of 4 per processor could be high as it means that there are frequent context switches - switches of processes or threads. But if you have high values of the runqueue then usually you have low CPU IDLE% and the CPU SYS% can increase.

 

[saythere]

Hi, Ademeter !

First, thanks for your help. I understand when you say
"it means that there are frequent context switches - switches of processes or threads", but can I do anything to get better or to revert that difficult situation ? Do you know if is there any parameter (AIX configuration)that I must to modify ?

Thanks again.

Saythere

 

[ademeter]

Hi Saythere,

are you running technical environment or database? If technical then modify the number of threads in your application. If database then I think you may have too many client processes, that may be OK.
You can do some tuning with the vmo, schedo and ioo commands (should be modified through smit) on AIX5.2 or vmtune and schedtune on AIX5.1 or AIX4.3.