hpux man page for eqmemsize

eqmemsize(5)							File Formats Manual						      eqmemsize(5)

NAME
       eqmemsize - determines the minimum size (in pages) of the equivalently mapped reserve pool (OBSOLETED)

DESCRIPTION
       This tunable has been obsoleted and removed.

       If  it  is  desired  to control the total amount of equivalently mapped memory available to the kernel after boot, then use the new tunable
       (see eqmem_limit(5)).

       Note that generally speaking, systems where it was useful to set will not need to set

       Equivalently mapped memory is memory which is given the same physical and virtual address.  On PA-RISC systems, this is required to support
       on-line addition of memory, and may be useful for some applications and some I/O devices.

       HP-UX  11i  Version  2  maintained a (small) reserve of equivalently mapped pages, which could be used for no other purpose.  It could also
       potentially equivalently map any page having a physical address below the maximum kernel virtual address, but only if it happened  to  find
       both  the virtual and physical addresses available; this rarely happened, except immediately after boot.  The tunable was used to size this
       reserve.  It was kept quite small, except on systems known to use such memory, where the reserve pool size would  be  increased	using  the
       tunable.

       The equivalent memory allocator was completely rewritten after HP-UX 11i Version 2.  The current version of the equivalent memory allocator
       decides, at boot, which pages it will consider to be equivalently mappable.  It makes the corresponding virtual addresses  unavailable  for
       other  purposes,  thereby  ensuring  that  if the physical page is available, it will be possible to map it equivalently.  This allows such
       pages to be used for other purposes, and still be reliably reused for equivalent mappings.  Thus  no  reserve  is  required.   The  tunable
       places a cap on the total amount of memory which will be considered equivalently mappable.

       Such  pages are treated almost identically to other pages, but not quite.  The differences only matter on Cache-Coherent Non-Uniform Memory
       Access (ccNUMA) systems, where in some circumstances these differences can result in reduced performance.  On such systems the tunable  may
       be  used  to  reduce  the  total amount of memory that will be designated equivalently mappable down to the maximum expected to actually be
       needed.	(Normally the kernel makes a very conservative estimate of the total  amount  that  might  be  needed.)   See  eqmem_limit(5)  for
       details.

AUTHOR
       was developed by HP.

SEE ALSO
       eqmem_limit(5).

OBSOLETED
						     Tunable Kernel Parameters						      eqmemsize(5)