Tribblix: manual page: mpss.so.1.1

MPSS.SO.1(1) User Commands MPSS.SO.1(1)

NAME

mpss.so.1 - shared object for setting preferred page size

SYNOPSIS

mpss.so.1

DESCRIPTION

The mpss.so.1 shared object provides a means by which the preferred
stack and/or heap page size can be selectively configured for
launched processes and their descendants. To enable mpss.so.1, the
following string needs to be present in the environment (see
ld.so.1(1)) along with one or more MPSS (Multiple Page Size Support)
environment variables:

LD_PRELOAD=$LD_PRELOAD:mpss.so.1

ENVIRONMENT VARIABLES

Once preloaded, the mpss.so.1 shared object reads the following
environment variables to determine any preferred page size
requirements and any processes these may be specific to.

MPSSHEAP=size
MPSSSTACK=size
MPSSHEAP and MPSSSTACK specify the
preferred page sizes for the heap and
stack, respectively. The specified page
size(s) are applied to all created
processes.

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

size can be qualified with K, M, G, or T
to specify Kilobytes, Megabytes,
Gigabytes, or Terabytes respectively.

MPSSCFGFILE=config-file
config-file is a text file which contains
one or more mpss configuration entries of
the form:

exec-name exec-args:heap-size:stack-size

exec-name specifies the name of an
application or executable. The
corresponding preferred page size(s) are
set for newly created processes (see
getexecname(3C)) that match the first
exec-name found in the file.

exec-name can be a full pathname, a base
name or a pattern string. See File Name
Generation in sh(1) for a discussion of
pattern matching.

exec-args is an optionally specified
pattern string to match against arguments.
Preferred page size(s) are set only if
exec-args is not specified or occurs
within the arguments to exec-name.

If heap-size and/or stack-size are not
specified, the corresponding preferred
page size(s) will not be set.

MPSSCFGFILE takes precedence over MPSSHEAP
and MPSSSTACK. When MPSSCFGFILE is not
set, preferred page size settings are
taken from file /etc/mpss.conf if it
exists.

MPSSERRFILE=pathname
By default, error messages are logged via
syslog(3C) using level LOG_ERR and
facility LOG_USER. If MPSSERRFILE contains
a valid pathname (such as /dev/stderr),
error messages will be logged there
instead.

EXAMPLES

Example 1: Configuring preferred page sizes using MPSSCFGFILE

The following Bourne shell commands (see sh(1)) configure the
preferred page sizes to a select set of applications with exec names
that begin with foo, using the MPSSCFGFILE environment variable. The
MPSS configuration file, mpsscfg, is assumed to have been previously
created via a text editor like vi(1). The cat(1) command is only
dumping out the contents.

example$ LD_PRELOAD=$LD_PRELOAD:mpss.so.1
example$ MPSSCFGFILE=mpsscfg
example$ export LD_PRELOAD MPSSCFGFILE
example$ cat $MPSSCFGFILE
foo*:512K:64K

Once the application has been started, pmap (see proc(1)) can be used
to view the actual page sizes configured:

example$ foobar &
example$ pmap -s `pgrep foobar`

If the desired page size is not configured (shown in the pmap
output), it may be due to errors in the MPSS configuration file or
environment variables. Check the error log (by default:
/var/adm/messages) for errors.

If no errors can be found, resource or alignment constraints may be
responsible. See the NOTES section.

Example 2: Configuring preferred page sizes using MPSSHEAP and

MPSSSTACK

The following Bourne shell commands configure 512K heap and 64K stack
preferred page sizes for all applications using the MPSSHEAP and
MPSSSTACK environment variables.

example$ LD_PRELOAD=$LD_PRELOAD:mpss.so.1
example$ MPSSHEAP=512K
example$ MPSSSTACK=64K
example$ export LD_PRELOAD MPSSHEAP MPSSSTACK

Example 3: Precedence rules (continuation from Example 2)

The preferred page size configuration in MPSSCFGFILE overrides
MPSSHEAP and MPSSTACK. Appending the following commands to those in

Example 2: would mean that all applications will be configured with

512K heap and 64K stack preferred page sizes with the exception of
those applications, the ls command, and all applications beginning
with ora that have ora1 as an argument, in the configuration file.

example$ MPSSCFGFILE=mpsscfg2
example$ export MPSSCFGFILE
example$ cat $MPSSCFGFILE
ls::
ora* ora1:4m:4m

FILES

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

/etc/mpss.conf
Configuration file

ATTRIBUTES

NOTES

The heap and stack preferred page sizes are inherited. A child
process has the same preferred page sizes as its parent. On exec(2),
the preferred page sizes are set back to the default system page size
unless a preferred page size has been configured via the mpss shared
object.

ppgsz(1), a proc tool, can also be used to set the preferred stack
and/or heap page sizes. It cannot selectively configure the page size
for descendents based on name matches.

See also NOTES under ppgsz(1).

February 20, 2002 MPSS.SO.1(1)