Re: Solaris T5220 server problem
- From: Pradeep Chetal <chetal@xxxxxxxxx>
- To: lawrence.wolfson@xxxxxxxxxx
- Date: Thu, 28 Apr 2011 17:47:51 -0400
Larry,
I cannot find much about how to turn page coalescing off.
Could you give the details.
Thanks,
Pradeep
On Wed, Apr 27, 2011 at 8:15 PM, Wolfson Larry - lwolfs <
lawrence.wolfson@xxxxxxxxxx> wrote:
> Hello!
>
> Finally convinced client long running code wasn’t database,
> application, network problem.
>
>
>
> Noticed when I was running one of *my* queries, that usually runs in a
> tenth of a second elapsed time, was taking about 8 seconds on production
> server
>
> 8G, 32 CPUs with both 10.2.0.4 prod & test (separate ORACLE_HOMES) on same
> server.
>
>
>
> Wanted Unix admin to run some type of Dtrace. I had already run truss a
> number of times.
>
> Didn’t get that, but SA found *echo* was running about 30-60 times longer
> on this server than dozens of others we manage (most not T5220s).
>
> They ran GUDS, which didn’t help and then support person came up with this
> from a buddy he reached out to.
>
>
>
> He suggested turning page coalescing off, which we found to be beneficial
> in many performance escalations. This is something you can do on the fly
> and if it's found to have a desirable effect, it can be permanently set in
> /etc/system. There are no know downsides to doing this in the real world.
>
>
>
> Once this is enabled, could your DBA's run some test jobs which can be
> compared against timings for the same jobs when the test DB is down?
>
>
>
> Here are the dirty details from previous communications on the topic:
>
> quote --->
>
> Large pages are not a problem. It is finding or coalescing them when none
> is available needs improvment. LPOOB feature is designed to improve
> application out of box performance. There are number of LPOOB fixes already
> been integrated in Sol10 U4 and more are planned for U5 and U6.
>
>
>
> It is wiser to disable coalescing than disable LPOOB. If you don't want
> page coalescing then set following tunables dynamically or in /etc/system
> file.
>
>
>
> And
>
> What I didn't mention before is that the page coalescing issue is
> specifically mentioned with the Niagara family of CPUs, which is what this
> T5220, is running on systems running Java applications and Oracle databases
> (the Oracle part being pertinent here.) Still not saying that it’s
> definitively going to resolve the problems, but it’s worth trying based on
> the system type, Oracle, and symptoms.
>
>
>
> This is dynamic change. Support person says we can easily toggle this back
> with no service interruption
>
> *Client is not buying that and I was just wondering what experience
> anyone else has had with T5220s?*
>
>
>
> Support said they did this mostly for SAP and while we run a number of
> SAPs, not on this server which I would categorize as relatively lightly
> loaded.
>
> Prod is far busier during nightly batch window. Scheduled stats run well
> prior to that for 3-13 minutes.
>
>
>
> Server and database have been up close to 2 years and they just noticed
> these processes running longer about 6 weeks ago.
>
> They put a new release in TEST but claim problem started just prior to
> that. Not refuting that.
>
>
>
> Thanks for any ideas, suggestions, experiences.
>
>
>
> Larry
>
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