madv.so.1(1) User Commands madv.so.1(1)
NAME
madv.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 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 getexec-
name(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 mem-
ory allocated in the future.
shm=advice Shared memory segments (see shmat(2)) attached using any flags, flag SHM_SHARE_MMU, or flag SHM_PAGEABLE respec-
ism=advice tively. Options ism and dism take precedence over option shm.
dism=advice
map=advice Mappings established through mmap(2) using any flags, flag MAP_SHARED, flag MAP_PRIVATE, or flag MAP_ANON, respec-
mapshared=advice tively. Options mapshared, mapprivate, and mapanon take precedence over option map. Option mapanon takes precedence
mapprivate=advice over mapshared and mapprivate.
mapanon=advice
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
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWesu (32-bit) |
+-----------------------------+-----------------------------+
| |SUNWesxu (64-bit) |
+-----------------------------+-----------------------------+
|Interface Stability |Unstable |
+-----------------------------+-----------------------------+
SEE ALSO
cat(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 sys-
tem libraries making direct system calls (for example, libthread allocations for thread stacks) are not affected.
SunOS 5.10 15 Feb 2002 madv.so.1(1)
