Thursday, 2 January 2014

Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports

There will be  Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports.

There may be following message in the ADDM report:

From  the ADDM report

FINDING 1: 100% impact (48628 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 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.

First, review the following bugs which incorrectly show large swapping statistics that may cause incorrect ADDM message as per
above message.  And if applicable, apply the bugs.

For 10.2.0.5,  for Linux:

Note:12347332.8 Bug 12347332 - V$OSSTAT / ADDM incorrectly shows very large swapping/paging stats

This bug is specific to Linux.  So download the patch for Linux:
Patch:12347332

For 11.2, there is the following bug:      

Note:10220118.8 Bug 10220118 - Print warning to alert log when system is swapping

If available for your os, download following patch:
Patch:10220118

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