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Home -> Community -> Mailing Lists -> Oracle-L -> Re: HIGH latch free Wait on moving from RBO to CBO?
Hi Vivek,
There are a number of hidden parameters changed in 9i that affected CBO (as compared to 8i CBO). I suggest contacting Oracle Support before changing any hidden parameters. I think this is know problem. If possible, test your application with 9.2.0.6. That seems to a stable version of 9i, so far.
Regards,
>
> ISSUE - Getting HIGH Latch Free Wait on the following Latches after moving from RBO to
> CBO. ( ALL Objects been analyzed at 100 %). CPU Usage on DB Server has gone up by about
> 30 %. NOTE - Application has also been migrated to a Higher release along with the CBO
> movement.
>
> Qs Any init.ora parameters to Tune ?
>
> Would increasing _shared_pool_reserved_min_alloc to 6140 from the Default of 4400 Help?
>
> Setting cursorsharing = FORCE/SIMILAR caused "%sys" component of CPU Usage to shoot to
> 99 % within minutes of Database startup. Seemed to be hitting some Bug in 9.2.0.5 (64
> Bit) on Solaris 9. Has anybody experienced this & is it solved in a 9i Higher Patch ?
> Which Patch on 9i is advisable?
>
> Qs Will Tuning of individual SQLs reduce this wait ?
>
> Any Other Advice please?
>
> Top 5 Timed Events
> ~~~~~~~~~~~~~~~~~~ % Total
> Event Waits Time (s) Ela Time
> -------------------------------------------- ------------ ----------- --------
> latch free 17,386,965 457,377 63.67
> CPU time 121,612 16.93
> db file sequential read 142,824,481 72,252 10.06
> log file sync 982,290 28,909 4.02
> db file scattered read 8,532,496 14,464 2.01
> -------------------------------------------------------------
> Wait Events for DB: UBIFIN Instance: UBIFIN Snaps: 1515 -1517
>
> Latch Activity for DB:
> Pct Avg Wait Pct
> Get Get Slps Time NoWait NoWait
> Latch Requests Miss /Miss (s) Requests Miss
> ------------------------ -------------- ------ ------ ------ ------------ ------
> cache buffers chains 4,141,035,268 0.3 1.2 0 311,630,019 26.7
> cache buffers lru chain 3,785,689 6.1 0.2 2300 321,104,446 25.1
> library cache 86,823,459 1.3 0.5 31780 56,524 17.4
>
>
> Database Size 1 TB , Number of Concurrent Users = 5000 ,
>
> Application Hybrid Application - Banking Product , Oracle 9.2.0.5 (64-Bit), Solaris 9,
> Number of CPUs on DB Server = 48
>
> Thanks Folks
>
> Vivek
>
> P.S. include my yahoo id (in CC) while replying please if possible
>
>
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-- http://www.freelists.org/webpage/oracle-lReceived on Thu Mar 02 2006 - 16:06:29 CST
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