ADDM Reports bug: Significant virtual memory paging was detected on the host operating system, addmpaging

ADDM Reports bug: Significant virtual memory paging was detected on the host operating system, addmpaging

When you view the ADDM report (the database version is ORACLE 10.2.0.5.0), it is very unreliable: Significant virtual memory paging was detected on the host operating system. the details are as follows:

FINDING 2: 100% impact (3930 seconds)

-------------------------------------

Significant virtual memory paging was detected on the host operating system.

   RECOMMENDATION 1: Host Configuration, 100% benefit (3930 seconds)

      ACTION: Host operating system was experiencing significant paging but no

         particular root cause could be detected. Investigate processes that

         do not belong to this instance running on the host that are consuming

         significant amount of virtual memory. Also consider adding more

         physical memory to the host.

Using nmon monitoring, we did not find that a large amount of virtual memory is consumed. After searching, we found that this was caused by a bug. This problem occurs in ORACLE 10 GB and ORACLE 11.

The official ADDM Reports Significant Virtual Memory Paging on Linux When None is Occurring (Document ID 1322964.1) is described as follows:

SYMPTOMS

After upgrading the database to 10.2.0.5, the ADDM report on Linux operation system may include findings on "Significant virtual memory paging ":

FINDING 1: 100% impact (32719 seconds)
--------------------------------------
Significant virtual memory paging was detected on the host operating system.

RECOMMENDATION 1: Host Configuration, 100% benefit (32719 seconds)
ACTION: Host operating system was experiencing significant paging
No Participant root cause cocould be detected. Investigate processes that
Do not belong to this instance running on the host that are
Consuming significant amount of virtual memory. Also consider adding more
Physical memory to the host.

There is no evidence at OS level of any problem with virtual memory paging. To verify that you are not really observing a memory problem, look at an operating system memory tool, such as vmstat:

oracle$ vmstat 5 5procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ r  b   swpd   free   buff  cache      si   so    bi    bo   in   cs us sy id wa st 1  0 670056 1184580  35772 12809336    0    0    26    40    1    5  3 27 68  1  0 0  0 670028 1183624  35788 12810980    0    0     7    22 1298 2534  3  1 90  6  0 1  0 670016 1171840  35804 12813436    0    0     2    34 1621 2691  5  1 77 16  0 1  0 669996 1175536  35816 12817064    0    0     6    19 1424 2957  9  2 77 12  0 0  0 669968 1183408  35840 12820460    0    0     8    28 1430 2850 14  3 73 10  0

Note: Under swap, si and so show a value of 0.
As abve, if there are no abnormal figures and you are still seeing this warning, you might me hitting this problem

 

 

CAUSE

This issue can be seen from 10.2.0.5 to 11.2.0.2

The problem is caused by wrong values in V $ OSSTAT as explained in:
Bug 10148787Addm reports virtual memory paging after applying 10.2.0.5
And unpublished Bug 11712010Virtual memory paging on 11.2.0.2 DATABASES.

ORACLE 10.2.0.5 can solve this BUG by downloading patch 12347332: TRACKING Bug to fix addm incorrectly reporting paging on 10.2.0.5