MADV.SO.1(1) User Commands MADV.SO.1(1)
NAME
madv.so.1 - madv library
SYNOPSIS
/usr/lib/madv.so.1DESCRIPTION
The
madv.so.1 shared object provides a means by which the VM advice can
be selectively configured for a launched process (or processes) and its
descendants. To enable
madv.so.1, the following string needs to be
present in the environment (see
ld.so.1(1)) along with one or more
MADV environment variables:
LD_PRELOAD=$LD_PRELOAD:madv.so.1ENVIRONMENT VARIABLES
If the
madv.so.1 shared object is specified in the
LD_PRELOAD list, the
following environment variables are read by the
madv shared object to
determine to which created process(es) to apply the specified advice.
MADV=
advice MADV specifies the VM advice to use for all
heap, shared memory, and mmap regions in the
process address space. This
advice is applied to all created processes.
Values for
advice correspond to values in
<sys/mman.h> used in
madvise(3C) to specify
memory access patterns:
normal
random
sequential
access_lwp
access_many
access_default
MADVCFGFILE=
config-file config-file is a text file which contains one
or more
madv configuration entries of the
form:
exec-name exec-args:
advice-opts Advice specified in
config-file takes
precedence over that specified by the
MADV environment variable. When
MADVCFGFILE is not
set, advice is taken from file
/etc/madv.conf if it exists.
exec-name specifies the name of an application
or executable. The corresponding advice is 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. Advice is
set only if
exec-args is not specified or
occurs within the arguments to
exec-name.
advice-opts is a comma-separated list
specifying the advice for various memory
region(s):
madv=
advice Applies to all heap,
shared memory, and mmap
regions in the process
address space.
heap=
advice The heap is defined to be
the brk area (see
brk(2)). Applies to the
existing heap and for any
additional heap memory
allocated in the future.
shm=
advice ism=
advice dism=
advice Shared memory segments
(see
shmat(2)) attached
using any flags, flag
SHM_SHARE_MMU, or flag
SHM_PAGEABLE respectively. Options
ism and
dism take precedence
over option
shm.
map=
advice mapshared=
advice mapprivate=
advice mapanon=
advice Mappings established
through
mmap(2) using any
flags, flag
MAP_SHARED,
flag
MAP_PRIVATE, or flag
MAP_ANON, respectively.
Options
mapshared,
mapprivate, and
mapanon take precedence over
option
map. Option
mapanon takes precedence
over
mapshared and
mapprivate.
MADVERRFILE=
pathname By default, error messages are logged via
syslog(3C) using level
LOG_ERR and facility
LOG_USER. If
MADVERRFILE contains a valid
pathname (such as
/dev/stderr), error messages
will be logged there instead.
EXAMPLES
Example 1: Applying advice to all ISM segments
The following configuration applies advice to all ISM segments for
application
/usr/bin/foo:
example$
LD_PRELOAD=$LD_PRELOAD:madv.so.1 example$
MADVCFGFILE=madvcfg example$
export LD_PRELOAD MADVCFGFILE example$
cat $MADVCFGFILE /usr/bin/foo:ism=access_lwp
Example 2: Setting advice for all applications with exception
The following configuration sets advice for all applications with the
exception of
ls.
example$
LD_PRELOAD=$LD_PRELOAD:madv.so.1 example$
MADV=access_many example$
MADVCFGFILE=madvcfg example$
export LD_PRELOAD MADV MADVCFGFILE example$
cat $MADVCFGFILE ls:
Example 3: Precedence rules (continuation from Example 2)
Because
MADVCFGFILE takes precedence over
MADV, specifying '
*' (pattern
match all) for the
exec-name of the last
madv configuration entry would
be equivalent to setting
MADV. The following is equivalent to example 2:
example$
LD_PRELOAD=$LD_PRELOAD:madv.so.1 example$
MADVCFGFILE=madvcfg example$
export LD_PRELOAD MADVCFGFILE example$
cat $MADVCFGFILE ls:
*:madv=access_many
Example 4: Applying advice for different regions
The following configuration applies one type of advice for mmap regions
and different advice for heap and shared memory regions for a select set
of applications with exec names that begin with
foo:
example$
LD_PRELOAD=$LD_PRELOAD:madv.so.1 example$
MADVCFGFILE=madvcfg example$
export LD_PRELOAD MADVCFGFILE example$
cat $MADVCFGFILE foo*:madv=access_many,heap=sequential,shm=access_lwp
Example 5: Applying advice selectively
The following configuration applies advice for the heap of applications
beginning with
ora that have
ora1 as an argument:
example$
LD_PRELOAD=$LD_PRELOAD:madv.so.1 example$
MADVCFGFILE=madvcfg example$
export LD_PRELOAD MADVCFGFILE example$
cat $MADVCFGFILE ora* ora1:heap=access_many
FILES
/etc/madv.conf Configuration file
SEE ALSO
cat(1),
ld.so.1(1),
proc(1),
sh(1),
brk(2),
exec(2),
fork(2),
memcntl(2),
mmap(2),
shmat(2),
getexecname(3C),
madvise(3C),
syslog(3C),
proc(5),
attributes(7)NOTES
The advice is inherited. A child process has the same advice as
its parent. On
exec() (see
exec(2)), the advice is set back to the
default system advice unless different advice has been configured via the
madv shared object.
Advice is only applied to
mmap regions explicitly created by the user
program. Those regions established by the run-time linker or by system
libraries making direct system calls (for example, libthread allocations
for thread stacks) are not affected.
February 15, 2002
MADV.SO.1(1)