Oracle ADDM report: “Significant Virtual Memory Paging Was Detected…”
During my experimentation with ADDM with Oracle10g on Windows 2003 x64 I found frequent warning at the top of the report, such as:
Significant virtual memory paging was detected on the host operating system.
RECOMMENDATION 1: Host Configuration, 100% benefit (8567 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.
I knew that this message is likely a bogus one, considering that Windows OS handles virtual memory a bit different than other operating systems. If you launch Task Manager you can easily observe Page Faults rapidly increasing during warm up phase of the Oracle instance (for example after fresh startup):
The other day I found Oracle official explanation:
Note:395957.1 ADDM Reports “Significant Virtual Memory Paging Was Detected On The Host Operating System”
My recommendation is that ADDM advice on Windows platform should be cross checked with OS trying to find out if real memory paging is going on. If you found that for example Oracle process Peak Memory Usage is (was) close to the amount of physical memory, it’s very likely that ADDM warning is not a bogus one and that real memory paging is going on, that need to be addressed.