Oracle-L: Re: 9i - Dynamic SGA

From: <Jared.Still_at_radisys.com>
Date: Mon, 04 Aug 2003 10:54:24 -0800
Message-ID: <F001.005C8D79.20030804105424@fatcity.com>

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 <kirtikumar_deshpande_at_yahoo.com> Sent by: ml-errors_at_fatcity.com
08/03/2003 12:29 PM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        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 <mgogala_at_adelphia.net> 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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Received on Mon Aug 04 2003 - 13:54:24 CDT