Re: db_block_lru_latches

If you aren't experiencing performance problems, the best thing to do is nothing.

>From the docs ( Designing and Tuning for Performance )

To determine whether your system is experiencing latch contention, begin by determining whether there is LRU latch contention for any individual latch.

SELECT CHILD#, SLEEPS / GETS RATIO
FROM V$LATCH_CHILDREN
WHERE NAME = 'cache buffers lru chain';

The miss ratio for each LRU latch should be less than 3%. A ratio above 3% for any particular latch is indicative of LRU latch contention and should be addressed.
You can determine the buffer pool to which the latch is associated as follows:

SELECT NAME
FROM V$BUFFER_POOL
WHERE lo_setid <= child_latch_number
AND hi_setid >= child_latch_number;

Jared

Hamid Alavi <hamid.alavi_at_quovadx.com>
Sent by: root_at_fatcity.com
07/03/2002 08:58 AM
Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        db_block_lru_latches

List,

I have a question regarding db_block_lru_latches, I have read in some book(can't remember) which the best number for this parameter is (number of
CPU)*6 or db_block_buffers/50.
But these two result is diffrent,anybody have any idea what's the best configuration for this parameter.
In my configuration it has been set to 1 as default and I have two CPU so it
means it should be 6*2 = 12?is it right? Thanks allot for your recommendation.  

Hamid Alavi
Office 818 737-0526
Cell 818 402-1987

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