Many thanks for comments on the following question:
> We are running an oracle database on an 8400 with 2G RAM. The
> database has an SGA of 1.3G - the idea is to run as much in memory
> as possible. We are running in over-committment mode and when the
> database is busy, swap space begins to be taken up as you would
> expect. However, when the database is quiet again the swap
> utilisation remains the same, often leaving very little spare.
> My question is: when do allocated pages of swap get freed up again?
> Is it only when the process owning them dies or when they are paged
> back into real memory?
Two similar answers were as follows:
processes can 'free' swap space but it doesn't get returned to the
general pool of swap space. It is held reserved for re-allocation by
that process. When that process dies, all memory is returned to the
general swap space pool.
and:
As far as I know, once a page is allocated from the page/swap space,
it stays allocated for the lifetime of the virtual memory. Even a
"free" of allocated memory may not free the space, since free memory
can be realloc'd.
Thanks again, Nick
Received on Mon Mar 02 1998 - 11:09:44 NZDT