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ppgsz(1)                         User Commands                        ppgsz(1)



NAME
       ppgsz - set preferred page size for stack, heap, and/or other anonymous
       segments

SYNOPSIS
       /usr/bin/ppgsz [-F] -o option[,option]  cmd | -p pid...

DESCRIPTION
       The ppgsz utility sets the preferred page size for stack, heap,  and/or
       other  anonymous  segments  for  the  target  process(es), that is, the
       launched cmd or the process(es) in the pid list. ppgsz stops the target
       process(es) while changing the page size. See memcntl(2).

OPTIONS
       The following options are supported:

       -F                      Force.  Sets the preferred page size options(s)
                               for target process(es) even  if  controlled  by
                               other  process(es). Caution should be exercised
                               when using the -F flag. See proc(1).



       -o option[,option]      The options are:


                               heap=size

                                   This option specifies  the  preferred  page
                                   size   for   the   heap   of   the   target
                                   process(es). heap is defined to be the  bss
                                   (uninitialized  data) and the brk area that
                                   immediately follows the bss  (see  brk(2)).
                                   The preferred heap page size is set for the
                                   existing heap and for any  additional  heap
                                   memory allocated in the future. See NOTES.




                               stack=size

                                   This  option  specifies  the preferred page
                                   size  for   the   stack   of   the   target
                                   process(es).  The preferred stack page size
                                   is set for the  existing  stack  and  newly
                                   allocated parts of the stack as it expands.



                               anon=size

                                   This  option  specifies  the preferred page
                                   size for all existing MAP_PRIVATE anonymous
                                   segments  of the target process(es),  other
                                   than heap and stack, which are large enough
                                   to  fit  at  least  one aligned page of the
                                   specified size. For the segments  that  are
                                   large  enough,  the  preferred page size is
                                   set  starting  at  the  first  size-aligned
                                   address  in the segment. The anon preferred
                                   pagesize  is  not  applied  to  MAP_PRIVATE
                                   anonymous  segments  created in the future.
                                   See MAP_ANON in mmap(2).

                                   Anonymous  memory  refers  to   MAP_PRIVATE
                                   pages that are not directly associated with
                                   a file in some filesystem. The  ppgsz  com-
                                   mand  uses  memcntl(2) to set the preferred
                                   page  size  for  anonymous  segments.   See
                                   MC_HAT_ADVISE in memcntl(2).


                               At least one of the above options must be spec-
                               ified.

                               size must be a supported page size  (see  page-
                               size(1))  or  0,  in which case the system will
                               select an  appropriate  page  size.  See  memc-
                               ntl(2).

                               size  defaults to bytes and can be specified in
                               octal (0), decimal, or  hexadecimal  (0x).  The
                               numeric value can be qualified with K, M, G, or
                               T to specify Kilobytes,  Megabytes,  Gigabytes,
                               or  Terabytes, respectively. 4194304, 0x400000,
                               4096K, 0x1000K, and 4M are  different  ways  to
                               specify 4 Megabytes.


       -p pid                  Sets  the preferred page size option(s) for the
                               target process(es) in the process-id (pid) list
                               following  the -p option. The pid list can also
                               consist of names in the /proc  directory.  Only
                               the  process owner or the super-user is permit-
                               ted to set page size.

                               cmd is interpreted  if  -p  is  not  specified.
                               ppgsz   launches  cmd  and  applies  page  size
                               option(s) to the new process.

                               The heap and stack  preferred  page  sizes  are
                               inherited.   Child   process(es)  created  (see
                               fork(2)) from the launched process or the  tar-
                               get  process(es)  in  the  pid list after ppgsz
                               completes will inherit the preferred  heap  and
                               stack  page  sizes. The preferred page sizes of
                               all segments are set back to the default system
                               page size on exec(2) (see getpagesize(3C)). The
                               preferred page size  for  all  other  anonymous
                               segments  is  not  inherited by children of the
                               launched or target process(es).



EXAMPLES
       Example 1: Setting the preferred heap and stack page size

       The following example sets the preferred heap page size to 4M  and  the
       preferred  stack page size to 512K for all ora--owned processes running
       commands that begin with ora:

       example% ppgsz -o heap=4M,stack=512K -p `pgrep -u ora '^ora'`

       Example 2: Setting the preferred anonymous page size

       The following example sets the preferred page size of existing qualify-
       ing anonymous segments to 512k for process ID 953:

       example% ppgsz -o anon=512k -p 953

EXIT STATUS
       If  cmd  is  specified and successfully invoked (see exec(2)), the exit
       status of ppgsz will be the exit status of cmd. Otherwise,  ppgsz  will
       exit with one of the following values:

       0        Successfully  set  preferred page size(s) for processes in the
                pid list.



       125      An error occurred in ppgsz. Errors include: invalid  argument,
                   invalid  page  size(s)  specified,  and failure to set pre-
                ferred page size(s) for one or more processes in the pid  list
                or cmd.



       126      cmd was found but could not be invoked.



       127      cmd could not be found.



FILES
       /proc/*                         Process files.



       /usr/lib/ld/map.bssalign        A   template  link-editor  mapfile  for
                                       aligning bss (see NOTES).



ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:


       tab()    allbox;    cw(2.750000i)|     cw(2.750000i)     lw(2.750000i)|
       lw(2.750000i).    ATTRIBUTE   TYPEATTRIBUTE  VALUE  AvailabilitySUNWesu
       (32-bit) SUNWesxu (64-bit) Interface StabilityEvolving


SEE ALSO
       ld(1), mpss.so.1(1), pagesize(1), pgrep(1), pmap(1),  proc(1),  brk(2),
       exec(2),   fork(2),   memcntl(2),  mmap(2),  sbrk(2),  getpagesize(3C),
       proc(4), attributes(5)

       Linker and Libraries Guide

NOTES
       Due to resource constraints, the setting of  the  preferred  page  size
       does not necessarily guarantee that the target process(es) will get the
       preferred page size. Use pmap(1) to view the actual heap and stack page
       sizes of the target process(es) (see pmap -s option).

       Large  pages  are required to be mapped at addresses that are multiples
       of the size of the large page. Given that the  heap  is  typically  not
       large  page aligned, the starting portions of the heap (below the first
       large page aligned address) are mapped  with  the  system  memory  page
       size. See getpagesize(3C).

       To provide a heap that will be mapped with a large page size, an appli-
       cation can be built using a link-editor (ld(1)) mapfile containing  the
       bss  segment  declaration  directive.  Refer  to  the section ``Mapfile
       Option'' in the Linker and Libraries Guide for  more  details  of  this
       directive      and     the     template     mapfile     provided     in
       /usr/lib/ld/map.bssalign. Users are cautioned that an alignment  speci-
       fication  may be machine-specific and may lose its benefit on different
       hardware platforms. A more flexible means of requesting the most  opti-
       mal underlying page size may evolve in future releases.

       mpss.so.1(1),  a preloadable shared object, can also be used to set the
       preferred stack and/or heap page sizes.



SunOS 5.10                        23 Jan 2003                         ppgsz(1)