AIX 6.1: Releasing Memory and Page Space


 
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Operating Systems AIX AIX 6.1: Releasing Memory and Page Space
# 1  
Old 01-26-2011
AIX 6.1: Releasing Memory and Page Space

Hi everyone,

i have a question about the Memory Management in AIX 6.1.
I have
- 128 GB RAM and
- 70 GB Page Space.
The application i am running on this machine is doing some operations in perl. These are done only once a day and uses both memory and paging space. My problem now is that when the application is finished with its operations the memory and page space are not released but hold. And this means ofr the next time that i will get a memory and page space overflow. I heard something about AIX 6.1 having a feature that does not allow the memory to be freed in order to do a faster processing for the next time. Someone told me about the parameters maxperm and minperm and that these values control this feature.

Anyone has some suggestions which values i should use?

this is the vmo -a output:
Code:
     ame_cpus_per_pool = n/a
       ame_maxfree_mem = n/a
   ame_min_ucpool_size = n/a
       ame_minfree_mem = n/a
       ams_loan_policy = n/a
   force_relalias_lite = 0
     kernel_heap_psize = 65536
          lgpg_regions = 0
             lgpg_size = 0
       low_ps_handling = 1
               maxfree = 1088
               maxperm = 29293578
                maxpin = 27041196
               maxpin% = 80
         memory_frames = 33554432
         memplace_data = 2
  memplace_mapped_file = 2
memplace_shm_anonymous = 2
    memplace_shm_named = 2
        memplace_stack = 2
         memplace_text = 2
memplace_unmapped_file = 2
               minfree = 960
               minperm = 976450
              minperm% = 3
             nokilluid = 0
               npskill = 138240
               npswarn = 552960
             numpsblks = 17694720
       pinnable_frames = 31259644
   relalias_percentage = 0
                 scrub = 0
              v_pinshm = 0
      vmm_default_pspa = 0
    wlm_memlimit_nonpg = 1

and this is the vmostat -v output:

33554432 memory pages
             32548422 lruable pages
             30013582 free pages
                    7 memory pools
              2295313 pinned pages
                 80.0 maxpin percentage
                  3.0 minperm percentage
                 90.0 maxperm percentage
                  1.6 numperm percentage
               529395 file pages
                  0.0 compressed percentage
                    0 compressed pages
                  1.6 numclient percentage
                 90.0 maxclient percentage
               529395 client pages
                    0 remote pageouts scheduled
                    1 pending disk I/Os blocked with no pbuf
              4761910 paging space I/Os blocked with no psbuf
                 2484 filesystem I/Os blocked with no fsbuf
                11444 client filesystem I/Os blocked with no fsbuf
               312559 external pager filesystem I/Os blocked with no fsbuf

Best,

Haichao

Moderator's Comments:
Mod Comment Please use [code] and [/code] tags when posting code, data or logs etc. to preserve formatting and enhance readability, thanks.

Last edited by zaxxon; 01-26-2011 at 11:01 AM.. Reason: code tags
# 2  
Old 01-26-2011
Hi,

let's start in the beginning - if you use paging space at all - you do not have enough memory.
Without knowing your box and what is running on it and what is normal and what is not there is no way to tell you what to do and what not to do.

So tell us something about your box. Post a vmstat -Iwt 2 10 output from a busy time (when you are filling up your pagingspace) and from a 'normal' time - so when your perl jobs do not run.

Show us an lsps -a output from a few min before your perl job is kicking in - so we know what is normal.

Show us a vmstat -s output.

There are many ways to clean up paging space if we need to - but since AIX is doing this on its own over time, you should never be in the situation of 'overflowing' memory and paging space in first instance when you do have enough memory in first instance - this will only happen when you are generally filling it up - what we do not know so far.

There are DB settings, filesystem mount options, system environment variables and finally system tunables that can help you - again we would need to know what else is on the box.

What might help you as well is to split your paging space - IBM doesnt recommend having paging spaces bigger 34 GB and it might help you with your issues of not enough buffers for pagingspaces and as well performance to split your paging area across multiple disks ...

Regards
zxmaus
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