xref: /illumos-gate/usr/src/man/man3c/posix_madvise.3c (revision 96c8483a3fb53529bbf410957b0ad69cfb5d9229)

Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.

The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their
documentation.

In the following statement, the phrase ``this text'' refers to portions
of the system documentation.

Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy
between these versions and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html.

This notice shall appear on any product containing this material.

The contents of this file are subject to the terms of the
Common Development and Distribution License (the "License").
You may not use this file except in compliance with the License.

You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
or http://www.opensolaris.org/os/licensing.
See the License for the specific language governing permissions
and limitations under the License.

When distributing Covered Code, include this CDDL HEADER in each
file and include the License file at usr/src/OPENSOLARIS.LICENSE.
If applicable, add the following below this CDDL HEADER, with the
fields enclosed by brackets "[]" replaced with your own identifying
information: Portions Copyright [yyyy] [name of copyright owner]


Copyright (c) 2001, The IEEE and The Open Group. All Rights Reserved.
Portions Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.

POSIX_MADVISE 3C "Jul 14, 2008"
NAME
posix_madvise - memory advisory information
SYNOPSIS

#include <sys/mman.h>

int posix_madvise(void *addr, size_t len, int advice);
DESCRIPTION

The posix_madvise() function advises the system on the expected behavior of the application with respect to the data in the memory starting at address addr, and continuing for len bytes. The system may use this information to optimize handling of the specified data. The posix_madvise() function has no effect on the semantics of access to memory in the specified range, although it may affect the performance of access.

The advice to be applied to the memory range is specified by the advice parameter and may be one of the following values: POSIX_MADV_NORMAL

Specifies that the application has no advice to give on its behavior with respect to the specified range. It is the default characteristic if no advice is given for a range of memory.

POSIX_MADV_SEQUENTIAL

Specifies that the application expects to access the specified range sequentially from lower addresses to higher addresses.

POSIX_MADV_RANDOM

Specifies that the application expects to access the specified range in a random order.

POSIX_MADV_WILLNEED

Specifies that the application expects to access the specified range in the near future.

POSIX_MADV_DONTNEED

Specifies that the application expects that it will not access the specified range in the near future.

These values are defined in <sys/mman.h>

RETURN VALUES

Upon successful completion, posix_madvise() returns zero. Otherwise, an error number is returned to indicate the error.

ERRORS

The posix_madvise() function will fail if: EINVAL

The value of advice is invalid.

ENOMEM

Addresses in the range starting at addr and continuing for len bytes are partly or completely outside the range allowed for the address space of the calling process.

The posix_madvise() function may fail if: EINVAL

The value of len is zero.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Committed
MT-Level MT-Safe
Standard See standards(5).
SEE ALSO

mmap(2), madvise(3C), posix_madvise(3C), attributes(5), standards(5)