illumos: 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)