Re: 11g RedHat 5 and Hugepages

From: Kevin Closson <ora_kclosson_at_yahoo.com>
Date: Wed, 13 Oct 2010 07:56:00 -0700 (PDT)
Message-ID: <6855.38381.qm_at_web57808.mail.re3.yahoo.com>

Nothing wrong with this feedback because it includes information about how to do it right (e.g., pooled connections). But therein lies my point. Take you 1GB SGA and attach a couple hundred dedicated connection and you'll wish you'd have either a) used huge pages or b) reduced your dedicated connection count. I wrote:

"Any system with large connection count is not going to be able to afford the wasted page table memory."

So, while this is a good follow up it isn't disagreeing at all with what I am said.

Oh, by the way, why on earth would anyone still be using a 32-bit OS? That is a larger question.

In summary, if you don't like the size of the page tables do something about it.

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From: "dbvision_at_iinet.net.au" <dbvision_at_iinet.net.au> To: Jon.Crisler_at_usi.com; tgascard_at_gmail.com; Kevin Closson <ora_kclosson_at_yahoo.com>
Cc: Oracle-L_at_freelists.org
Sent: Tue, October 12, 2010 11:31:39 PM
Subject: Re: 11g RedHat 5 and Hugepages

Beg to disagree there, Kevin. Hugepage setup - in Linux, mind you - is more a hindrance than an advantage until one starts to talk about SGA sizes of much more
than a couple GBs.

Hardly possible in 32-bit OS's, where with luck one gets an SGA of 2GB, if that. Of course I'm not including things like Wintel's weird windowed large memory handling for 32-bit Windows. Not even sure if that one is handled with a TLB, looks like the old PC Expanded memory?

Systems with large connection counts nowadays are handled with pooled connections
in 99% of the cases. I've lost memory of the last application server I've seen that didn't use some form or other of that for large number of connections. And there is always MTS/Shared connection/whatever-its-name-is-nowadays. :)

Don't get me wrong, though: I've been asking folks for a long time to use hugepages with 64-bit OS's. No doubt whatsoever in my mind it has an advantage for the larger SGA sizes so common in those. In fact, I'm continually surprised it's not a default setup for Oracle in 64-bit OS's!

Cheers
Nuno

On Wed Oct 13 2:26 , Kevin Closson sent:

>Also, this notion that 32bit OS deployments don't need hugepages is quite
wrong.
Any system with large connection count is not going to be able to afford the wasted page table memory.
>
>Use hugepages.

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Received on Wed Oct 13 2010 - 09:56:00 CDT