We covered a similar issue with sort_area_size in Tim Gorman's seminar at
IOUG in April.
Unless brk() is called, the memory is not returned to the OS.
Jared
Kirtikumar Deshpande <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
08/03/2003 12:29 PM
Please respond to ORACLE-L
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Subject: Re: 9i - Dynamic SGA - SGA_MAX_SIZE
Thanks, Mladen. That makes sense.
One just needs to make sure (by testing) that the OS supports this
feature.
- Kirti
--- Mladen Gogala <[EMAIL PROTECTED]> wrote:
> Kirti, problem is in the malloc mechanism. The subroutine to free the
memory
> doesn't return it to the OS, it returns it to the "allocation pool
instead.
> As a consequence, when oracle does "free", its address space is not
going to
> go down. You realize, of course, that malloc, calloc, realloc and free
are the
> only options, because of their portability. There are low level
allocation
> routines like brk() to increase the address space, but unaware of any
routine
> to decrease the address space. Here is the manual page for the library
> subroutine called "mallopt", which is mostly obsolete but still exists
on
> HP-UX. The mechanism remained the same, but the control was taken away
from
> the users. Manual page does illustrate the mechanism, though.
> malloc(3C) malloc(3C)
>
<snip>
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