Re: Large pages
Date: Fri, 23 Nov 2012 04:34:07 -0800 (PST)
Message-ID: <cf03a1ef-544c-47fa-8c98-c07aa16a684b_at_googlegroups.com>
Den fredag den 23. november 2012 04.26.40 UTC+1 skrev Noons:
> On Nov 23, 7:59 am, hhkr..._at_gmail.com wrote:
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> > Yep, that's what I was trying to achieve. Thanks for testing this, I'll be sure to remember this if we ever get to upgrade AIX - as of now we're on AIX 5.3 ML08, so I cannot even get to play with 11gR2.
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> One thing: you don't need 11gr2 for Aix 7.1. 10.2.0.3 works perfectly
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> well, I have it here. Although it isn't *officially* supported.
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> The only thing I found in 10g doesn't work with Aix 7.1 is largepages
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> and again that might have been an error of mine. Everything else
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> seems to work perfectly fine. In fact that's how I upgraded most of my
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> dbs:
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> upgrade Aix to 7.1, start instance in 10g, use dbua to upgrade it to
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> 11g.
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> Strangely enough, dbua 11g logs in to the database before it starts
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> its upgrade. How on earth do they expect it to be up if it is being
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> upgraded? (rolling eyes...)
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> I had to leave the 10g ORACLE_HOME intact, with the db running. dbua
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> was then run from the 11g ORACLE_HOME and proceeded to do all the
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> transformations to the db and changes to ORACLE_BASE from 10g setup to
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> 11g.
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> > ( I say *if* we ever get to upgrade: These AIX boxes also host some Oracle 8.1.7.4 databases (don't laugh), which we cannot upgrade because an application based on Webdb 2.2 - stop that laughter, I said! )
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> Aye.... That was my first battle here, nearly 6 years ago. Had
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> everything and the kitchen sink running, including 7.1 in Windows NT 4
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> server! Took me a couple of years to get EVERYTHING in 10g and Aix
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> 5.3. And now it's almost all there in 11gr2 and 7.1.
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> Except for Peoplesoft's HR, - of course, it *HAD* to be an Oracle
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> application...
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> > BTW I have only made small attempts at looking into large pages on AIX, but your old blog entry on dbasrus.blogspot.dk about how to do it is bookmarked for when I finally get the time!
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> Sure. You don't have to use largepages until you are into VERY large
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> SGAs, >> 10GB. That's where it really makes a difference. I've found
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> it improves overall CPU performance by an average of 10% once a SGA in
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> the tens of GBs gets moved to largepages. And upgrading to Aix 7.1
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> and Oracle 11gr2 gave me another el-cheapo 15% CPU gain (on Power 6 h/
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> w)! I've got the Unix performance graphic to show it in the
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> SydneyOracle meetup library, "11g Upgrade adventure" presentation:
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> http://www.sydneyoracle.com.au/files/
What I have tested on 10.2.0.4 databases on AIX 5.3 is backing them by 64K pages, in reference to an IBM document: http://www.scribd.com/doc/50959984/Tuning-IBM-AIX-5-3-and-AIX-6-1-for-Oracle-Database and also input from Doug Burns and Maxym Kharchenko: http://intermediatesql.com/aix/can-oracle-11g-memory_target-work-with-aix-large-pages/ and also input from some MetaLink notes.
Quote from page 13 of IBM's document:
"The new 64 KB pages are preferred over 16 MB pages, and it is recommended that you use them instead of 16 MB pages on systems that support both page sizes. This is because 64 KB pages provide most of the benefit of 16 MB pages, without the special tuning requirements of 16 MB pages."
In my tests it was as simple as:
export ORACLE_SGA_PGSZ=64k
export LDR_CNTRL=DATAPSIZE=64K_at_TEXTPSIZE=64K_at_STACKPSIZE=64K
before starting up the database.
Quote confusingly 'ps' still reports 4K for the SHMPGSZ column: ps -fZ -p "$(ps -ef | grep ora_smon_ | grep -v grep | awk '{print $2}')" but the other columns report 64K, and using 'vmstat -P all' you can see that the SGA is backed by 64K pages. Received on Fri Nov 23 2012 - 13:34:07 CET