RE: 11g AMM tmpfs vs hugepages for best overall performance
- From: "Crisler, Jon" <Jon.Crisler@xxxxxxx>
- To: <ora_kclosson@xxxxxxxxx>, <howard.latham@xxxxxxxxx>
- Date: Wed, 28 Jul 2010 10:18:08 -0400
Kevin, I read all of your blog entries, and my take on it was that you
did not have a clear opinion on the performance advantage of 11g AMM vs.
Linux hugepages, especially for large systems. In my case, I am
working with RAC servers that have 96 gb of memory, dedicated to running
a single db. The SGA and PGA combined could easily be 64gb or higher.
What we plan to do is have a large /dev/shm (tmpfs) so we can change
between hugepages and AMM if a direction becomes clear. In speaking
with some internal folks at Oracle, for really large systems there seems
to be a feeling that hugepages might have the edge. Their stance is
basically that people tend to mess up hugepages allocations frequently,
causing far worse performance and a support headache, while AMM is far
easier to manage and has less chance of allowing people to shoot
themselves in the foot. But if the dba knows how to manage hugepages,
it might have a performance edge. At this point I don't know what the
benchmark or performance testing plan is, other than perhaps Swingbench
against the app.
Your blogs are the only source that I have seen that touches on this
topic, and I have read all of them. I especially liked the NUMA
entries.
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Closson
Sent: Friday, July 23, 2010 4:19 PM
To: howard.latham@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: 11g AMM tmpfs vs hugepages for best overall performance
It depends on how much memory you have spare to waste. See the blog
entries...
________________________________
From: Howard Latham <howard.latham@xxxxxxxxx>
To: ora_kclosson@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Sent: Fri, July 23, 2010 11:30:01 AM
Subject: Re: 11g AMM tmpfs vs hugepages for best overall performance
Do we need huge pages with 64 bit Oracle?
On 23 July 2010 18:03, Kevin Closson <ora_kclosson@xxxxxxxxx> wrote:
>does not have any performance conclusions
It's a capacity issue more than a performance issue. However, if you run
out of capacity your performance will be impacted. Don't confused Linux
hugepages with most of the Unix derivations that implement huge pages
with shared page tables. Shared page tables is a performance feature.
http://kevinclosson.wordpress.com/kevin-closson-index/2009/07/28/quantif
ying-hugepages-memory-savings-with-oracle-database-11g/
BTW, 11gR1? Really?
________________________________
From: "Crisler, Jon" <Jon.Crisler@xxxxxxx>
To: D'Hooge Freek <Freek.DHooge@xxxxxxxxx>; oracle-l@xxxxxxxxxxxxx
Sent: Thu, July 22, 2010 4:51:47 PM
Subject: RE: 11g AMM tmpfs vs hugepages for best overall performance
Thanks- I saw this blog, but he does not have any performance
conclusions on hugepages vs. 11g AMM for larger systems. On smaller, 32
bit systems there was no clear winner.
-----Original Message-----
From: D'Hooge Freek [mailto:Freek.DHooge@xxxxxxxxx]
Sent: Wednesday, July 21, 2010 12:11 PM
To: Crisler, Jon; oracle-l@xxxxxxxxxxxxx
Subject: RE: 11g AMM tmpfs vs hugepages for best overall performance
Jon,
Yes, you can still pick between AMM and "normal" memory parameters.
For the comparison, I suggest you look at the following blogpost of
Kevin Closson:
http://kevinclosson.wordpress.com/2007/08/23/oracle11g-automatic-memory-
management-and-linux-hugepages-support/
Regards,
Freek D'Hooge
Uptime
Oracle Database Administrator
email: freek.dhooge@xxxxxxxxx
tel +32(0)3 451 23 82
http://www.uptime.be
disclaimer: www.uptime.be/disclaimer
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Crisler, Jon
Sent: woensdag 21 juli 2010 18:03
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: 11g AMM tmpfs vs hugepages for best overall performance
And a follow up question- if I implement a large /tmpfs - shm, I can
still use choose to not use AMM and use hugepages, correct ?
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Crisler, Jon
Sent: Wednesday, July 21, 2010 11:57 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: 11g AMM tmpfs vs hugepages for best overall performance
Which is better for performance on large Red Hat 5 systems (64gb+
memory, 8+ cpu's) - using 10g style shm settings and hugepages, OR the
newer 11g Automatic Memory Manager (which does not support hugepages).
The system I am building is a 6 node 11g R1 RAC, memory somewhere
between 64gb and 256gb (not sure yet), 8 cpu per node. This machine
will support a huge workload.
--
//www.freelists.org/webpage/oracle-l
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Howard A. Latham
Sent from my Nokia N97
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