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Question and Answer

Connor McDonald

Thanks for the question, mrunmayi.

Asked: April 18, 2017 - 2:55 pm UTC

Last updated: April 19, 2017 - 9:13 am UTC

Version: 12c

Viewed 1000+ times

You Asked

hello,

i would like to know the use of Huge pages in 12c for performance improvements. we got suggestion for implementing the Huge pages for performance improvements. could you advice on this??

thanks

and Connor said...

Its mainly about management of memory. Lets say you have 300 connections to the database. They all access a large shared memory stucture (the SGA), and they all need to maintain a mapping to those memory pages.

So try this on your system:

grep PageTables /proc/meminfo

That will be the amount of memory you are consuming for page tables. That is not "good" memory, ie, stuff your application benefits from. That is memory needed just for the *management* of those processes dealing with memory structures. It is easy to burn *gigabytes* of memory for these page tables, because each page is very small.

How do we solve that ? Make each page much bigger... hence huge pages.

So if you have a lot of a connection, or a really large SGA, then huge pages is generally a no brainer.

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A reader, April 19, 2017 - 5:51 am UTC

Could you elaborate with a simple example?
Connor McDonald
April 19, 2017 - 9:13 am UTC

"So try this on your system:

grep PageTables /proc/meminfo"


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