RE: Important: Oracle processes taking lots of CPU
- From: John Kanagaraj <john.kanagaraj@xxxxxxx>
- To: "'New DBA'" <new_dba_on_the_block@xxxxxxxxx>, ORACLE-L@xxxxxxxxxxxxx
- Date: Wed, 24 Nov 2004 11:12:48 -0800
Hi New DBA,
>As I understand, the CPU is used while performing
>LIOs, doing calculation, sorts or while spinning for
>the latches. My understanding might be wrong! Since
>there aren't enough LIOs or complex calculations
>involved I thought that spinning for latches might be
>causing excessive CPU.
Spinning does cause CPU issues. I believe that if you have many processes
and comparatively lesser number of processors, then you might have a lot of
CPU consumption that is unaccounted for as cycles used for process context
switching is not accounted in oracle. You will have to then look at 'sar -u'
( look for high %sys), 'sar -q' (look for high run queue size and occupancy)
and 'sar -w' (look for excessive process switches).
Let us know if this helps,
John Kanagaraj <><
DB Soft Inc
Phone: 408-970-7002 (W)
http://tahiti.oracle.com - Manuals for DBAs (English only)
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