ppgsz(1) User Commands ppgsz(1)NAMEppgsz - 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:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWesu (32-bit) │
├─────────────────────────────┼─────────────────────────────┤
│ │SUNWesxu (64-bit) │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Evolving │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOld(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)
