Re: shared pool latch time out exceeding 40% HELP!!!

Hi,

This is an HP-UX specific comment, as far as I know. We were having bad latch contention, and we ended up having the SPIN_COUNT set to 10,000 on an HP-UX v10.20 and Oracle7 v7.3.4 database configuration. Ok, I know that you have moved on with your configuration (11 and 8.0.5), but you might want to look at possibly running a test with a high SPIN_COUNT.

Rgds
Andrew

Kunihito Ishibashi wrote:

> upon doing further investigation of the oracle db problem that we
> wereexperiencing
> (cpu usage exceeding 100%), we discovered that the db isnot successfully
> obtaining the "latch" necessary to perform a transaction
> (in trying to obtain the latch, oracle goes through an excessive number
> ofloops).
>
> with the spin count set to 2,000 and using oracle's estat/bstat tool,
> we obtained the below results. according to oracle's documentation, the
> xxx latch time out
> statistics should not exceed 1%. however, in our tests,the shared pool
> latch time out percentage
> reached approximately 40% (out of10 million transaction, 3.9 million of the
> transactions failed).
> referring once again to oracle's documentation, it is noted that increasing
> the shared pool
> size to 300000000 its current value should improve performance
> (in other words, reduce the shared pool latch time out percentage to a more
> reasonable percentage).
> however, making such changes did not yield any improvement.
>
> we are wondering whether this is a problem with the HP-UX B.11.00 or with
> oracle8.0.5.1.0.
>
> any feedback is appreciated. thank you...
>
> xxx LATCH TIMEOUT (oracle's estat/bstat):
> ROW_CACHE_OBJECT 5%
> SHARD_POOL 40%
> LIBRARY_CACHE 12%
> REDO_ALLOCATION 0.09%
> REDO_COPY 0.05%
>
> SERVER SPEC:
> HP-UX k580a B.11.00 E 9000/800 (th) 32bit
> CPU PA-8200 x 6
> MEMORY 2GB
> DISK EMC SYMMETRIX MODEL3430 (5GB MEMORY/800GB DISK)
> EMC POWERPATH RELEASE 1.3
> ORACLE RELEASE 8.0.5.1.0
Received on Fri Apr 30 1999 - 20:58:24 CDT