Re: Buffer cache LRU
Date: Mon, 4 Jan 2010 09:57:58 -0600
Message-ID: <2b0cd5cd1001040757p441a2cedgfe8b60eb9be4d5b6_at_mail.gmail.com>
Thanks Chris And Tim for providing this document. I had gone through that document but i was wondering if i can get this information
As oracle 11g Documentation says for all dirty, cold , free and hot there is only one list is maintained. May be i am interpreting wrong.
I was under impression that there is a different LRU which is LRUW for write list but this says LRU maintains both cold, dirty, free, hot all pointers.
- How to you find that particular buffer in hot, cold or dirty ?
- How to find buffer is in which list LRU or LRUW ?
To find this do we need SGA dump and if yes where to find this information."
On Mon, Jan 4, 2010 at 9:48 AM, Stephens, Chris <Chris.Stephens_at_adm.com>wrote:
> He also has a very nice book recently published that goes into cache
> details among other things.
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Tim Gorman
> *Sent:* Sunday, January 03, 2010 2:13 PM
> *To:* taral.desai_at_gmail.com
> *Cc:* oracle-l_at_freelists.org
> *Subject:* Re: Buffer cache LRU
>
>
>
> Back in 2004 or so, Craig Shallahamer explained Oracle touch-count
> mid-point insertion algorithm (quite a bit more involved than mere
> "least-recently-used"), downloadable at
> "http://resources.orapub.com/product_p/tc.htm"<http://resources.orapub.com/product_p/tc.htm>
> ...
>
>
>
>
>
> Taral Desai wrote:
>
> Hi All,
>
>
>
> Few Doubts regarding oracle buffer cache. Here is the documentation link
> from 11g R2.
>
>
>
>
> http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/memory.htm#i12483
>
>
>
> Which Says
>
>
>
> "The database uses a sophisticated algorithm to make buffer access
> efficient. Pointers to dirty and nondirty buffers exist on the same *least
> recently used (LRU) list*, which has a hot end and cold end. A *cold* *
> buffer* is one that has not been recently used. A *hot buffer* is
> frequently accessed and has been recently used."
>
>
>
> Now, i was under impression that there is a different LRU which is LRUW for
> write list but this says LRU maintains both cold, dirty, free, hot all
> pointers.
>
>
>
> Can someone please explain this and also i had few question
>
>
>
> 1. How to you find that particular buffer in hot, cold or dirty ?
>
> 2. How to find buffer is in which list LRU or LRUW ?
>
>
>
>
>
> To find this do we need SGA dump and if yes where to find this information.
>
>
>
>
>
> --
>
> Thanks & Regards,
> Taral Desai
> Samuel Goldwyn<http://www.brainyquote.com/quotes/authors/s/samuel_goldwyn.html> - "I'm willing to admit that I may not always be right, but I am never
> wrong."
>
> -- http://www.freelists.org/webpage/oracle-l
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-- Thanks & Regards, Taral Desai Samuel Goldwyn<http://www.brainyquote.com/quotes/authors/s/samuel_goldwyn.html> - "I don't think anyone should write their autobiography until after they're dead." -- http://www.freelists.org/webpage/oracle-lReceived on Mon Jan 04 2010 - 09:57:58 CST