Re: Hugepages - benefits / drawbacks
Date: Tue, 7 Oct 2008 16:30:56 -0400
With default setting of _use_ism_for_pga set to TRUE - no changes in shared memory segments (pmap -s/pmap -x) were observed during sorting operation. Speaking of mmap/brk calls - no such calls happened _during the sort_ according to truss output. Looks like PGA is not using ISM despite the underscore parameter 8-). Oracle 10.2.0.3, Solaris 10.
On Tue, Oct 7, 2008 at 3:08 PM, Yong Huang <yong321_at_yahoo.com> wrote:
> ipcs probably won't show anything interesting. Can you check truss output
> when you do a big sort (select count(*) from dba_source order by 1)? Filter
> on calls such as brk, mmap (get args of this). Also pmap -x | grep shmid.
> See if the mapped size increases when you do big sorting. And, pmap -s <your
> shadow process> to see which page size segment increases its size.
> Yong Huang
> --- On Tue, 10/7/08, Roman Podshivalov <roman.podshivalov_at_gmail.com>
> > From: Roman Podshivalov <roman.podshivalov_at_gmail.com>
> > Subject: Re: Hugepages - benefits / drawbacks
> > To: yong321_at_yahoo.com
> > Cc: "Christo Kutrovsky" <kutrovsky.oracle_at_gmail.com>,
> oracle-l_at_freelists.org, krishmanoh_at_gmail.com
> > Date: Tuesday, October 7, 2008, 1:59 PM
> > Yep that parameter caught my attention too. I just did a
> > quick test and
> > started database with this parameter set to true and false.
> > No difference in
> > ipcs -ma output was found....Could that be related to MTS
> > configuration ?
> > --romas
> > On Tue, Oct 7, 2008 at 2:55 PM, Yong Huang
> > <yong321_at_yahoo.com> wrote:
> > > > On Tue, Oct 7, 2008 at 1:26 PM, Yong Huang
> > > > <yong321_at_yahoo.com> wrote:
> > > > > Hi Krishna,
> > > > >
> > > > >> on Solaris PGA uses ISM
> > > > >
> > > > > Wouldn't that cause PGA to be shared?
> > >
> > > Tanel Poder's presentation "Memory Management
> > and Latching Improvements in
> > > Oracle9i and 10g" mentions the parameter
> > _use_ism_for_pga. It didn't
> > > register in my mind when I read it some time ago. I
> > don't have access to
> > > Oracle on Solaris right now. Why does Oracle do this?
> > It would be
> > > interesting to see the effect.
> > >
> > > Yong Huang