HOW TO SET UP LARGE PAGES:

These instructions are appropriate for either AIX 5.1C or AIX 5.1D,
but the performance details differ significantly because the page
placement policies differ. See below for more details.

1. Set up the Kernel (AIX 5.1C or AIX 5.1D)

   The system admin must do all of these things to get a large-page segment:
   1) AIX 5.1C only: kernel must be 64bit
   2) "vmtune -g 268435456 -L <# of 256MB regions to reserve>"
      (Note that vmtune is in the "bos.samples" package on the AIX CD-ROMs.)
      "bosboot -a" and reboot
      The examples in this directory need at least 16 256 MB regions.
      AIX 5.1D should also support a page size specification of 16777216.
   3) "vmtune -S 1" (after reboot) to enable pinned shared memory
   4) AIX 5.1C only: test application must be 64bit
   5) AIX 5.1C only: test application must set the SHM_LGPAGE and SHM_PIN
      flags on shmget call
   6) AIX 5.1C only: test application must request a multiple of 256MB for
      the size

2. For AIX 5.1C:
   Build the application following the example "stream_driver.f".
   Instructions are in the "README" file in this directory.

   For AIX 5.1D:
   The approach shown here is not needed, and the recommended
   approach is to use the loader option to map all the data
   segments onto large pages local to the MCM running the process.

3. For AIX 5.1C:
   Note that on a multi-MCM system, the large page segment(s)
   may be placed on any MCM with memory.  You are guaranteed
   that each 256 MB aligned region is on one MCM, and it is 
   very likely that all of the 256 MB aligned regions will be
   located on the same MCM (until it runs out of memory, and
   the allocator moves to another MCM).

   For AIX 5.1D:
   Large pages will be allocated in a "round-robin" fashion
   among all the MCMs with installed memory.  If you access 
   the large pages using the "shmget" approach shown in the
   stream_driver.f program in this directory, your pages will
   be interleaved across the MCMs with memory, on 16 MB 
   boundaries.  In contrast, if you use the loader option to
   select large pages, they will be placed on the MCM where 
   your job is running (assuming any large pages are available
   on that MCM).

4. Remember that System V shared memory segments are persistent.
   Use "ipcs" to see what you accidentally left out there, and
   "ipcrm" to delete the old one(s).   I recommend running under
   your normal user id (not root) since root has many segments
   out there for other reasons, and it is easy to get confused
   about which one(s) to delete.

5. This software is delivered "as-is", with no warranties 
   expressed or implied.  This software is not supported by
   IBM.

/* (C) COPYRIGHT International Business Machines Corp. 2001           */
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