Re: LOCK_SGA on HPUX

On 12/12/2004 05:22:12 AM, Jaffar_DBA wrote:
> Friends,

>=20

Personally, I am not locking my SGA in memory. If you lock your entire =20 SGA in memory, then swapper cannot swap out parts of the SGA that are =20 not used and update daemon cannot steal unused SGA pages and throw them out to disk. In other words, you are taking control of a large part of =20 your memory away from the virtual memory system. If there are many =20 processes accessing database and if you are using dedicated server (for =20 instance, if you want to take advantage of the automatic work are =20 sizing) the memory of your server is guaranteed to become extremely =20 busy. Frequently used pages will stay in memory because of the nature =20 of the virtual memory system which does its best to keep frequently =20 used things in memory. If there is a procedure locked in SGA by using =20 dbms_shared_pool.keep, which is used once, or twice during the course =20 of the day, then you don't necessarily want to keep pages containing =20 this procedure in memory and you can allow your VM system to page them =20 out and create a sort area for your busy DW users. In other words, your =20 VM system already does a good job with balancing your memory. You =20 should trust it.

--=20
Mladen Gogala
Oracle DBA

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