Re: private memory used by oracle process in AIX ??

  • From: J.Velikanovs@xxxxxxxx
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 9 Jul 2004 10:26:51 +0300

Hi Prem,
Are you aware regarding UNIX virtual memory mechanisms?
I am asking because from vmstat, ps, top and others OS tools, which 
aggregate memory utilization information (RSS, VSZ etc) we can?t see for 
sure how many Memory utilizing each process. 
This is because VSZ figure include not just privet memory areas, but also 
shared memory (like SGA) and TEXT (code). RSS represent VSZ process memory 
which in RAM at the moment (other part swapped).
The way how different OS-es show RSS, VSZ figures differs from one OS to 
other, but principles preserve.
.
Some OS-es have tools which allows to see in details all memory areas. For 
example:
Solaris - /usr/proc/bin/pmap
Linux - cat /proc/<pid>/maps

Unfortunately I unaware of such tool on AIX.
PS If you will find one, please share this information.

I you are interesting to investigate dipper, how UNIX manage and reflect 
information about memory utilization, then I would recommend to read ?The 
SolarisMemorySystem Sizing,ToolsandArchitecture? from Sun. Document about 
Solaris, but main concepts are the same for UNIXes.

Any body, please correct me, in case I am wrong,
Best regards,
Jurijs
9268222
============================================
http://otn.oracle.com/ocm/jvelikanovs.html

PS One way how you can try to calculate the MEM utilizations by each 
Oracle process (with known approximately), is to select sorted list of all 
DB processes memory utilization (VSZ), take the smallest one and subtract 
the figure from others processes VSZ. This method assume, that smallest 
process use all shared memory as others DB processes, but privet part is 
insignificant. Doesn?t work if you using JVM.






"Prem Khanna J" <premj@xxxxxxxxxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
09.07.2004 08:05
Please respond to oracle-l
 
        To:     oracle-l@xxxxxxxxxxxxx
        cc: 
        Subject:        private memory used by oracle process in AIX ??


Hi All,
the env is oracle 9.2.0.4/AIX5.2

# ps v 1495162
PID      PGIN  SIZE   RSS   LIM  TSIZ   TRS   %CPU %MEM COMMAND
1495162  40    9068   32272 xx   48602  23204  0.0  1.0 ora_pmon

which will give me the private memory of the above process :
RSS - TRS 
or
(RSS - TRS )*4

RSS & TRS are reported in kb. whereas an AIX memory page is 4096 bytes.
doc 123754.1 seems to be confusing.
it says to mulitply the difference by 4 , where as it doesn't in the 
example shown in the doc.

can someone guide me which is the right way ?

Regards,
Prem.
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