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Old 03-17-2004, 01:38 PM   #1
Registered: Jan 2003
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AIX System running slow


I am running out of real memory on my RS6000

do you have any funky tips if fixing this type of problem, apart from buying more mem

I have run top but can't see what is chewing up all the mem, how can I see what mem all running processes are using.

Old 03-17-2004, 04:49 PM   #2
Registered: Nov 2002
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svmon is the command you want.

Something like svmon -Pu -t 5 should show the top 5 processes (this will work on 5.2, if you have a different version and it isn't working right, check the man page. If svmon isn't installed on your system, you'll need to install it (can't remember the fileset right now - I'll check tomorrow). I think you get a ton of information on each process so some filtering might be in order.

As for what you can do about it...usual stuff I guess. See if there are processes you don't need, or something that's grabbing more memory than it should. See if there's anything you can move to a different system. If you've got memory hogs that you can recompile, see if you can improve the memory footprint that way.
Old 03-18-2004, 09:33 AM   #3
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Just checked and /usr/bin/svmon is in fileset on AIX 5.2.
Old 03-19-2004, 11:19 AM   #4
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Re: AIX System running slow

Originally posted by Greenman

I have run top but can't see what is chewing up all the mem, how can I see what mem all running processes are using.
You definately want to use topas, not top in AIX. It is a lot more informative. Also verfiy that your paging space is setup correctly, you can use lsps -a and you can see where and how big the space. The svmon command works as well as mentioned by iainr
Old 03-20-2004, 11:49 PM   #5
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Don't forget to see if you have enough disk space....
Old 03-21-2004, 05:19 PM   #6
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If you are "running out of memory," you must determine if it is actually memory overcommitment or fake paging (assuming that the system is using paging space). Memory overcommitment occurs where the in-core memory requirements are larger than real memory. Fake paging occurs because of improper settings of minperm and maxperm. Understanding memory in AIX is a non-trivial topic. I have written about this topic in IBM's eServer magazine. The articles are posted on my Website:

Good Luck!
Old 04-15-2004, 09:45 AM   #7
Mark Taylor
Registered: Apr 2004
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when you say your running out of memory ? you mean that you are paging to paging space ? or the free page list is low ?

AIX by default will allow as much memory to be consumed as possible until you hit minfree, then lrud will start looking for pages as candidates to page out based on the least recently used algorythm. if they are file pages (persisteint) then the page will be flushed back to the filesystem and the memory page put back on the free list.. if its a computational (working) page, then it is flushed to paging space.... only when you hit minfree will this start to happen..(by default.. you can use strict_maxperm to limit your filesystem cache size and start paging file pages out before the minfree setting is hit).

Ok, saying that... you need to post some vmstat, vmtune (vmo on aix 5.2), lsps -a output so we can see whats going on.

please post the following info...

lsattr -EHl mem0
vmstat 1 15 # when system is under load
lsps -a
/usr/samples/kernel/vmtune # aix 433, 5.1
vmo -L # 5.2

Old 04-22-2004, 04:37 AM   #8
Registered: Feb 2004
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Hi, Greenman,
Did you solve your problem ?


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