madv.so.1(1) User Commands madv.so.1(1)NAMEmadv.so.1 - madv library
SYNOPSIS
/usr/lib/madv.so.1
DESCRIPTION
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.1
ENVIRONMENT 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 prece‐
dence over that specified by the MADV envi‐
ronment variable. When MADVCFGFILE is not
set, advice is taken from file
/etc/madv.conf if it exists.
exec-name specifies the name of an applica‐
tion 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 pat‐
tern 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 speci‐
fying 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 Shared memory segments
ism=advice (see shmat(2)) attached
dism=advice using any flags, flag
SHM_SHARE_MMU, or flag
SHM_PAGEABLE respec‐
tively. Options ism and
dism take precedence
over option shm.
map=advice Mappings established
mapshared=advice through mmap(2) using
mapprivate=advice any flags, flag
mapanon=advice MAP_SHARED, flag
MAP_PRIVATE, or flag
MAP_ANON, respectively.
Options mapshared, map‐
private, and mapanon
take precedence over
option map. Option
mapanon takes prece‐
dence 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 mes‐
sages 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
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │system/extended-system- │
│ │utilities (32-bit) │
├─────────────────────────────┼─────────────────────────────┤
│ │SUNWesxu (64-bit) │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Uncommitted │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOcat(1), ld.so.1(1), proc(1), sh(1), brk(2), exec(2), fork(2), mmap(2),
memcntl(2), shmat(2), getexecname(3C), madvise(3C), syslog(3C),
proc(4), attributes(5)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 alloca‐
tions for thread stacks) are not affected.
SunOS 5.11 15 Feb 2002 madv.so.1(1)