NMON- Analyzing Memory Usage

Recently, got request to clarify the  AIX Memory utilization from application team  . After going through lot of documentations , this was what i was able to understand .  .  

Total virtual :36 GB  >>>  this total memory allocated which includes physical and paging space .

Accessed virtual : 16.3 GB --   Active virtual pages  in memory (including pagespace + real memory) which comes around 45.3%

In AIX  Virtual Memory Management  , The free memory will be used for cache and whenever application request for memory , it will freed automatically .  

In our latest report below is the physical memory consumption .

%used =93.7%   -- it is the total  physical memory used out of 32 GB (i.e process+system +cache)

Note:  This will be always high  in AIX  as it includes the cache also .

%free =  6.3%

This section  of NMON provides details how is the physical memory used  and the differentiation –refer below attached screenshot  .

Numperm(cache) =41.9%      >>> this is used for cache purpose(filesystemcache etc)  for better performance and will be freed up automatically by the Operating system when application requests for memory.

Process                = 40.4%      >>> this much of physical memory out of 32 GB is used by application process

System                = 11.4%      >>>  This much of memory is used by the Operating system processes out of 32 GB

Free                    =6.3%         >>>  This is free physical memory available out of 32 GB

Basically when we talk about performance we consider only “process+system”  . If this is above 90 -95% , then we can see performance impact .