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Full Discussion: Strange memory behavior
Operating Systems AIX Strange memory behavior Post 302722077 by -=XrAy=- on Friday 26th of October 2012 10:09:26 AM
Old 10-26-2012
Strange memory behavior
Hello together,

i have a strange memory behavior on a AIX 7.1 System, which i cannot explain.
The Filesystem-Cache will not be grow up and drops often after few minutes. I know if a file was deleted, that the same segment in the FS-Cache will also be cleared. But i am not sure if this is the correct explanation for "my" behavior.

In one test i read a file (dd if=<some file> of=/dev/null) and after the dd finished the fs-cache (file pages) immediately droped out of the memory, but i couldn't reproduce this test.

Does anyone have an idea?
Thanks

P.S.
- tunables like vmo or schedo was not changed
- the System has a lot of nfs V3 exports

Code:
# vmstat -v
              6553600 memory pages
              6274304 lruable pages
              3778457 free pages
                    2 memory pools
              1204754 pinned pages
                 90.0 maxpin percentage
                  3.0 minperm percentage
                 90.0 maxperm percentage
                  5.4 numperm percentage
               342616 file pages
                  0.0 compressed percentage
                    0 compressed pages
                  5.4 numclient percentage
                 90.0 maxclient percentage
               342558 client pages
                    0 remote pageouts scheduled
                34333 pending disk I/Os blocked with no pbuf
                    0 paging space I/Os blocked with no psbuf
                 2228 filesystem I/Os blocked with no fsbuf
                73667 client filesystem I/Os blocked with no fsbuf
               284352 external pager filesystem I/Os blocked with no fsbuf
                 37.1 percentage of memory used for computational pages

Code:
#lparstat -i
Type                                       : Shared-SMT-4
Mode                                       : Uncapped
Entitled Capacity                          : 2.00
Partition Group-ID                         : 32820
Shared Pool ID                             : 3
Online Virtual CPUs                        : 4
Maximum Virtual CPUs                       : 8
Minimum Virtual CPUs                       : 1
Online Memory                              : 25600 MB
Maximum Memory                             : 61440 MB
Minimum Memory                             : 2048 MB
Variable Capacity Weight                   : 4
Minimum Capacity                           : 0.10
Maximum Capacity                           : 4.00
Capacity Increment                         : 0.01
Maximum Physical CPUs in system            : 64
Active Physical CPUs in system             : 32
Active CPUs in Pool                        : 12
Shared Physical CPUs in system             : 12
Maximum Capacity of Pool                   : 3200
Entitled Capacity of Pool                  : 420
Unallocated Capacity                       : 0.00
Physical CPU Percentage                    : 50.00%
Unallocated Weight                         : 0
Memory Mode                                : Dedicated
Total I/O Memory Entitlement               : -
Variable Memory Capacity Weight            : -
Memory Pool ID                             : -
Physical Memory in the Pool                : -
Hypervisor Page Size                       : -
Unallocated Variable Memory Capacity Weight: -
Unallocated I/O Memory entitlement         : -
Memory Group ID of LPAR                    : -
Desired Virtual CPUs                       : 4
Desired Memory                             : 25600 MB
Desired Variable Capacity Weight           : 4
Desired Capacity                           : 2.00
Target Memory Expansion Factor             : -
Target Memory Expansion Size               : -
Power Saving Mode                          : Disabled

Strange memory behavior-memoryjpg
Last edited by -=XrAy=-; 10-26-2012 at 11:18 AM..
 

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