RE: PLSQL CPU consumption

A guess : cursor_space_for_time trigger premature flush out of shared pool of high number of objects hence cpu activity, specialy in DB with sql without bind.

                The effect would be similiar to a small SGA.
 
 

B. Polarski

From: Bobak, Mark [mailto:Mark.Bobak_at_il.proquest.com] Sent: Tuesday, 26 September, 2006 3:06 PM To: panandrao_at_gmail.com; ade.turner_at_gmail.com Cc: oracle-l_at_freelists.org
Subject: RE: PLSQL CPU consumption

Um, how is cursor_space_for_time "known to be CPU bound"? It will certainly cause higher memory usage, but how does it affect CPU consumption?      

-- 
Mark J. Bobak 
Senior Oracle Architect 
ProQuest Information & Learning 

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From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Anand Rao
Sent: Tuesday, September 26, 2006 12:49 AM
To: ade.turner_at_gmail.com
Cc: oracle-l_at_freelists.org
Subject: Re: PLSQL CPU consumption


Hi,

i would try disabling cursor_space_for_time. it is known to be CPU
bound. not very sure how much of that is affecting you. your wait event
suggests libary cache issues. i am no good with ref cursors, so i can't
really comment on that. 

could be that there are large no. of copies of the same statement or
that your packages / sql are getting invalidated from inside another
proc. needs more diagnosis for sure.

just try,

cursor_space_for_time=false 

and bounce your instance.

your next step is to drill down into V$SQL, V$SQLAREA and all those
packages. do you use a lot of SQL from inside those packages?

cheers
anand




On 26/09/06, Adrian <ade.turner_at_gmail.com> wrote: 

	Hi David,

	 

	Sorry, I'm not onsite (UK based) so cant give you exact info,
but  pretty much

	 

	Latch Free(librarycache)            50%

	CPU Time,                                45%

	sequential read(much lower)       5%

	 

	The latch frees only appear under CPU starvation. Under normal
load its 90% to CPU Time.

	 

	Tkprof output does not seem to show the considerable cpu time
attributed by v$sqlarea to the package call.

	 

	Cheers

	Adrian 

	 

	


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	From: David Sharples [mailto:davidsharples_at_gmail.com] 
	Sent: 25 September 2006 20:33
	To: ade.turner_at_gmail.com
	Cc: oracle-l_at_freelists.org
	Subject: Re: PLSQL CPU consumption

	 

	what are you biggest wait  / timed events




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