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High Paging when lots of free memory AIX 5.3

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Operating Systems AIX High Paging when lots of free memory AIX 5.3
# 8  
Old 08-29-2014
Thanks, is there any calculation possible to find out the optimum value for the tunable parameters, or if I tweak these values how much it is going to contribute to my current high paging utilization issue.

Code:
$ $ svmon -G
               size       inuse        free         pin     virtual
memory      9437184     9424496       12688     1796740     8576772
pg space    7864320     2000371

               work        pers        clnt       other
pin         1490348           0           0      306392
in use      7671239           0     1753257

PageSize   PoolSize      inuse       pgsp        pin    virtual
s   4 KB          -    3481600     346035    1655556    2022452
m  64 KB          -     371431     103396       8824     409645
$ lsps -s
Total Paging Space   Percent Used
      30720MB              26%
$ vmstat -vs
          26994260366 total address trans. faults
           4361829552 page ins
           3820265318 page outs
             84045532 paging space page ins
             77865859 paging space page outs
                    0 total reclaims
           8236127852 zero filled pages faults
             11712277 executable filled pages faults
          15174415073 pages examined by clock
                25517 revolutions of the clock hand
           5331955580 pages freed by the clock
             65710515 backtracks
               175898 free frame waits
                    0 extend XPT waits
            284609239 pending I/O waits
           8157163408 start I/Os
            855241712 iodones
          43057036717 cpu context switches
          16995406850 device interrupts
           1964838815 software interrupts
          20009814065 decrementer interrupts
            165822097 mpc-sent interrupts
            165822048 mpc-received interrupts
           1353839635 phantom interrupts
                    0 traps
         192398322217 syscalls
              9437184 memory pages
              9048488 lruable pages
                11106 free pages
                    5 memory pools
              1796740 pinned pages
                 80.0 maxpin percentage
                 20.0 minperm percentage
                 50.0 maxperm percentage
                 19.3 numperm percentage
              1750906 file pages
                  0.0 compressed percentage
                    0 compressed pages
                 19.3 numclient percentage
                 50.0 maxclient percentage
              1750906 client pages
                    0 remote pageouts scheduled
                 4760 pending disk I/Os blocked with no pbuf
             15264944 paging space I/Os blocked with no psbuf
                 1972 filesystem I/Os blocked with no fsbuf
                27374 client filesystem I/Os blocked with no fsbuf
               411174 external pager filesystem I/Os blocked with no fsbuf
                    0 Virtualized Partition Memory Page Faults
                 0.00 Time resolving virtualized partition memory page faults

Last edited by Don Cragun; 08-29-2014 at 05:46 PM.. Reason: Remove duplicated data.
# 9  
Old 08-29-2014
Hi Bibish,

Have had a look back here several times and as this is beginning to intrigue me, I'd like to investigate this a little further.. It has been some time since I worked on AIX, but I did do a fair bit with 5.3 and 6.1 back in the day.

There are some things that you should be aware of, as far as the page and swap goes along with the run queue and the CPU I/O wait. These parameters are heavily interdependent in AIX, quite often giving rise to apparent performance issues where there aren't any.

So having read over a report that I prepared about 30 months ago, for a group of AIX systems with around 15K users - I'd like to clarify a couple of things. These are just simple info gathering steps!

Is there a perceivable degradation in performance when the swapping happens?

Is the problem repeatable in any shape or form?

Does the reboot always clear the problem?

Regards

Dave
This User Gave Thanks to gull04 For This Post:
bibish
# 10  
Old 09-01-2014
Hello Dave,

We havnt noticed any performance impact but the paging utilization keep on increasing and eventually we have to restart the application every day to bring it back to normal.

This issue we are monitoring every day for couple of weeks now but with same application with other AIX 5.3 server even with less physical memory utlizing only 2-3% ram in the environment.

yes restarting the application or restarting the system always clear this issue.

Bibish
# 11  
Old 09-01-2014
There looks to be a memory leak in the application you restart. If the OS, patches and hardware are the same on the affected server than the ones where the issue doesn't show up, there is unlikely anything you can fix with kernel tuning.

Please post statistics about the leaking process, not just global ones.
# 12  
Old 09-01-2014
Hi Bibish.

As Jllagre says this is almost certainly application related, what I think you'll have to do here is check the applications are at the same versions. If that is the case - you'll probably have to investigate whey one is holding leaked memory and the other isn't. Most likely down to the way the application is being used if they are both the same.

If these systems are at the same MU level then I think you'll need application support to resolve.

Regards

Dave
Last edited by gull04; 09-01-2014 at 04:35 AM.. Reason: Spelling
# 13  
Old 09-07-2014
Well basically no matter how much 'free' memory the system has - with minperm set to 20% the host will inevitably page when it uses 34GB memory computational out of 36GB available - especially as long as numperm is at 20%.
As zaxxon said, fix the minperm setting (to 3% or 5%) and figure out if you really need to keep cached content in memory even though the corresponding IO has been completed. If not mount your filesystems with rbrw option. Not sure if you mentioned if this is an app or a DB server - but if its i.e. oracle, you may want to consider cio and/or filesystem_io_options=SETALL
Regards
zxmaus
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