Re: DISM in 11.2.0.2 on Solaris 10
- From: Tanel Poder <tanel@xxxxxxxxxxxxxx>
- To: Amir.Hameed@xxxxxxxxx
- Date: Wed, 20 Jul 2011 21:02:37 +0300
Yep it could be a bug ... but if not, then my theory would be something like
this:
1) The oradism process gets started up even when you don't actually use DISM
because it's also required for setting high priority processes (like VKTM &
LMS processes - as specified by _high_priority_processes parameter). This is
because you need root privs to raise the priority of a process and oradism
(with root setuid) provides that.
So perhaps that's the reason why the oradism process gets started despite
you not using DISM.
2) And now when the oradism gets started, why is there more than one process
now - and why does it seem to be dependent on SGA size. This may be due to
the fact that DISM memory is not locked to their physical memory locations
by default. So, when extending/creating SGA, the dism process must call
mlock() to lock these pages to RAM... and this mlock() call may likely have
to walk through all the pages in the segment individually. Especially as
DISM can fall back to small pages (when there's not enough contiguous large
page frames available) then this locking activity may take a while (and burn
kernel mode CPU). That would especially hurt you on the T-series CPUs where
a single thread is dead slow. So, perhaps they've decided to parallelize
this mlocking activity and it's not a bug at all.
Let us know how it goes :-)
--
Tanel Poder
http://blog.tanelpoder.com
On Wed, Jul 20, 2011 at 5:31 PM, Hameed, Amir <Amir.Hameed@xxxxxxxxx> wrote:
> David,
> Thank you for the feedback.
> I have already validated all DISM related parameters from SQL*Plus as
> well as by creating PFILE from SPFILE and none of the below mentioned
> parameters are set. The Oracle analyst that I am working with has filed
> a BUG with development (BUG# 12771380).
>
> Thanks
> Amir
>
> -----Original Message-----
> From: David Robillard [mailto:david.robillard@xxxxxxxxx]
> Sent: Wednesday, July 20, 2011 9:38 AM
> To: Hameed, Amir
> Cc: oracle-l mailing list
> Subject: Re: DISM in 11.2.0.2 on Solaris 10
>
> Hello Amir,
>
> > Date: Tue, 19 Jul 2011 09:59:03 -0400
> >
> > I have a two-node Oracle RAC 11.2.0.2 environment running multiple
> > databases on M3000 servers. Both servers are identical in
> configuration
> > with the exception that server A has twice the amount of physical
> memory
> > than server B (64GB versus 32GB). The following parameters are NOT set
> > in the SPFILE and therefore, DISM should not be enabled:
> >
> > SGA_TARGET
> > SGA_MAX_SIZE
> > MEMORY_MAX_TARGET
> > MEMORY_TARGET
> >
> > However, when I run the "ps" command at the OS, I observe the
> following:
>
> Take a look at appendix D < Administering Oracle Database on Solaris >
> in the < Oracle Database Administrator's Reference 11g Release 2
> (11.2) for Linux and UNIX-Based Operating Systems >. It's stated how
> and why Oracle uses Intimate Shared Memory on Solaris 10. (I'd give
> you the URL, but the documentation site appears to be down at the
> moment).
>
> If you "create pfile=''/tmp/pfile.txt'' from spfile;" can you see if
> the above parameters are set? If so, that might explain things.
>
> HTH,
>
> David
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
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