1.\" $OpenBSD: madvise.2,v 1.14 2007/05/31 19:19:32 jmc Exp $ 2.\" $NetBSD: madvise.2,v 1.7 1995/12/27 21:17:02 jtc Exp $ 3.\" 4.\" Copyright (c) 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93 32.\" 33.Dd $Mdocdate: May 31 2007 $ 34.Dt MADVISE 2 35.Os 36.Sh NAME 37.Nm madvise 38.Nd give advice about use of memory 39.Sh SYNOPSIS 40.Fd #include <sys/types.h> 41.Fd #include <sys/mman.h> 42.Ft int 43.Fn madvise "void *addr" "size_t len" "int behav" 44.Sh DESCRIPTION 45The 46.Fn madvise 47system call 48allows a process that has knowledge of its memory behavior 49to describe it to the system. 50The possible behaviors are: 51.Bl -tag -width MADV_SEQUENTIAL 52.It Dv MADV_NORMAL 53No further special treatment needed. 54.It Dv MADV_RANDOM 55Expect random page access patterns. 56.It Dv MADV_SEQUENTIAL 57Expect sequential page references. 58.It Dv MADV_WILLNEED 59The pages will be referenced soon. 60.It Dv MADV_DONTNEED 61The pages will not be referenced soon. 62.It Dv MADV_SPACEAVAIL 63Ensure that resources are reserved. 64.It Dv MADV_FREE 65The pages don't contain any useful data and can be recycled. 66.El 67.Sh RETURN VALUES 68Upon successful completion, 69a value of 0 is returned. 70Otherwise, a value of \-1 is returned and 71.Va errno 72is set to indicate the error. 73.Sh SEE ALSO 74.Xr mincore 2 , 75.Xr minherit 2 , 76.Xr mprotect 2 , 77.Xr msync 2 , 78.Xr munmap 2 79.Sh HISTORY 80The 81.Nm madvise 82function first appeared in 83.Bx 4.4 . 84