AIX 6.1 memory tuning Post: 302887753

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Operating Systems AIX AIX 6.1 memory tuning Post 302887753 by bakunin on Monday 10th of February 2014 04:13:12 PM

02-10-2014

Registered User

Quote:

Originally Posted by dzodzo

vmstat -v shows that about 20% of memory pages are pinned (that would roughly correspond to those 13 GB for kernel). Does it mean that application doesn't use memory pinning (server is running Oracle+SAP)? svmon tells me that oracle and workprocesses use about 33 MB of pinned memory, perhaps it's the way they are designed. I'll have to check on some testing system what happens, if you continually increase memory for aplication, how it will affect OS behaviour.

hmmm....

First off: Oracle is indeed using "pinned memory", because "pinned memory" is normal memory, but not allowed to be swapped out. Oracle uses it for its "SGA" (system global area) on one hand and for shared memory on the other. If you are interested in the details of allocated shared memory i suggest you use the ipcs command to analyze which process owns which shared memory segment. I can warmly recommend the man page of ipcs, it is a phantastic read.

Second: yes, the kernel accumulates memory over time, but for a different reason: "file memory" is part of the memory accounted to the kernel too, because the kernel "owns" it, so to say. When the system starts and hasn't done anything it has no idea what to put into file cache, so it is initially empty. Over time it is filled and less important things get thrown out in favor of more important ones. The vmo parameters "lru_file_repage", "maxperm" and "minperm" steer the process and i suggest you read up on the vmo command (which sets these options) to understand the process better.

By the way, as Oracle has its own file caching mechanism built into the SGA it might be a wise idea to make the SGA bigger and diminish the AIX filecache accordingly. You might also consider changing the maxperm parameter to 97% instead of its current 90%, but this will probably not have a big effect if the shown values are typical for your machines load.

I hope this helps.

bakunin

bakunin

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dsktune

DSKTUNE(1)						      General Commands Manual							DSKTUNE(1)

NAME

       dsktune - reports memory, network, and file system tuning settings which can affect the performance of the Directory Server

SYNOPSIS

       dsktune [-q] [-c] [-D] [-v] [-i installdir]

DESCRIPTION

       Reports memory, network, and file system tuning settings which can affect the performance of the Directory Server

OPTIONS

       A summary of options is included below:

       -q     dsktune only reports essential settings

       -c     dsktune only reports tuning information for client machines

       -D     dsktune also reports the commands executed

       -v     dsktune only reports its release version date

       -i installdir
	      specify alternate server installation directory

AUTHOR

       dsktune was written by the 389 Project.

REPORTING BUGS

       Report bugs to http://bugzilla.redhat.com.

COPYRIGHT

       Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
       Copyright (C) 2008 Red Hat, Inc.
       This manual page was written by Michele Baldessari <michele@pupazzo.org>, for the Debian project (but may be used by others).
       This is free software.  You may redistribute copies of it under the terms of the Directory Server license found in the LICENSE file of this
       software distribution.  This license is essentially the GNU General Public License version 2 with an exception for plug-in distribution.

								   May 18, 2008 							DSKTUNE(1)