Re: 10.2.0.4 / New Hugepages / JDBC Thin connections slow connect ?

From: Nuno Souto <dbvision_at_iinet.net.au>
Date: Wed, 26 Jun 2013 20:35:53 +1000
Message-ID: <51CAC409.3000708_at_iinet.net.au>

With hugepages and assuming no use of AMM - yes, I know in some OS hugepages and AMM are incompatible, stay with me here until the end of the paragraph! - the SGA is reserved in one go. That doesn't mean *ALL* memory structures will be pre-filled: they may well not be referenced for a while. Doesn't mean they don't get reserved. In Aix and without AMM, the reservation of hugepages is immediate on startup and it doesn't budge until shutdown. I don't know what happens with AMM as I refuse to use it.

-- 
Cheers
Nuno Souto
dbvision_at_iinet.net.au


On 26/06/2013 1:58 AM, Christopher.Taylor2_at_parallon.net wrote:


> I thought that was AIX (others?) specific but that's a good question.  Seems like I read that AIX does that but not positive.

>

> Actually, I know for sure that it doesn't on Linux because it RESERVES hugepages but doesn't use them - you can watch the free hugepages count go down as Oracle claims memory I believe.  I'll try to verify on my end however.

>

> Chris

>

>

> -----Original Message-----

> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Josh Collier

> Sent: Tuesday, June 25, 2013 10:34 AM

> To: oracle-l_at_freelists.org

> Subject: RE: 10.2.0.4 / New Hugepages / JDBC Thin connections slow connect ?

>

> When you have enabled huge pages, and verified that your SGA is going into the huge pages pool, Doesn't the SGA get pre-paged regardless of this particular parameter (pre_page_sga)?

>

> The way I understand it, with huge pages enabled, the SGA is loaded(paged-in) completely on instance startup.  Do I have a misunderstanding?

>

> Josh C

>


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Received on Wed Jun 26 2013 - 12:35:53 CEST