Hello listers,
For those of you who are on Solaris - did you notice that 19c changed the
way it allocates os shared memory segments when using AMM (MEMORY_TARGET) ?
When checking with "pmap -xs" I am finding that it is not creating OSM
(Optimized Shared Memory) segments.
This was not happening in 12.1 and 12.2.
Instead it creates numerous non-locked allocations in regular shared memory
segments.
Not OSM, not ISM and not DISM. Just regular shmid.
Which of course makes them pageable and swappable and not a good thing.
Even pmap -x runs noticeably slower.
I also noticed that USE_LARGE_MEMORY value flips to False with AMM.
This also was not happening in 12.1 and 12.2.
According to the doc *"This parameter is applicable only on the Linux
operating system. However, setting this parameter to FALSE can cause
performance degradation on any platform"*
Which makes me wonder - why does 19c flip it to false with AMM if it causes
degradation ?
I have SR where support confirmed that USE_LARGE_MEMORY flipping to false
with AMM started in 19c.
In SR they also stated that I should NOT try to set it back to true wen
doing AMM (which I tested succeeds in making AMM use OSM segments again )
Anybody knows of another way to make 19c use OSM Solaris segments with AMM ?
Thank you
Albert
