Re: Buffer cache LRU
- From: Taral Desai <taral.desai@xxxxxxxxx>
- To: "Stephens, Chris" <Chris.Stephens@xxxxxxx>, "tim@xxxxxxxxx" <tim@xxxxxxxxx>
- Date: Mon, 4 Jan 2010 09:57:58 -0600
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.
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."
On Mon, Jan 4, 2010 at 9:48 AM, Stephens, Chris <Chris.Stephens@xxxxxxx>wrote:
> He also has a very nice book recently published that goes into cache
> details among other things.
>
>
>
> *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Tim Gorman
> *Sent:* Sunday, January 03, 2010 2:13 PM
> *To:* taral.desai@xxxxxxxxx
> *Cc:* oracle-l@xxxxxxxxxxxxx
> *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."
>
> -- //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."
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