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A question about LRU in shared pool [message #419538] Mon, 24 August 2009 02:21 Go to next message
serenaender
Messages: 4
Registered: August 2009
Junior Member
Hi,

I have a doubt about how LRU algorythm works. LRU is supossed to ages out unpinned recreatable chunks when it needs free space. So, as there is enough space LRU will not work.

However, why don't we always notice shared pool memory usages close to 100%? Is there any other event that triggers LRU apart from this lack of memory such time in shared pool?

As i guess, if LRU only works when there isn't enough free space and ages out the space that needs, the shared pool should be like a bucket filling up with water. However, the optimal memory usage is supossed to be close to 70%.

Thanks before hand.
Re: A question about LRU in shared pool [message #419570 is a reply to message #419538] Mon, 24 August 2009 05:10 Go to previous messageGo to next message
Michel Cadot
Messages: 64132
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
There are many independent areas in shared pool and many chains.
Now how do you calculate usage?

Regards
Michel
Re: A question about LRU in shared pool [message #419575 is a reply to message #419570] Mon, 24 August 2009 05:54 Go to previous messageGo to next message
serenaender
Messages: 4
Registered: August 2009
Junior Member
I usually use Statspak or AWR reports. In the shared pool statistics section appears the shared pool memory usage.


Re: A question about LRU in shared pool [message #420268 is a reply to message #419575] Fri, 28 August 2009 00:05 Go to previous message
trantuananh24hg
Messages: 668
Registered: January 2007
Location: Ha Noi, Viet Nam
Senior Member
serenaender wrote on Mon, 24 August 2009 17:54
I usually use Statspak or AWR reports. In the shared pool statistics section appears the shared pool memory usage.



What's kind of shared_pool statistics on your AWR and Statspack?
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