1.\" $NetBSD: madvise.2,v 1.16 2002/02/08 01:28:19 ross Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93 35.\" 36.Dd June 9, 1993 37.Dt MADVISE 2 38.Os 39.Sh NAME 40.Nm madvise 41.Nd give advice about use of memory 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]sys/mman.h\*[Gt] 46.Ft int 47.Fn madvise "void *addr" "size_t len" "int behav" 48.Sh DESCRIPTION 49The 50.Fn madvise 51system call 52allows a process that has knowledge of its memory behavior 53to describe it to the system. 54The known behaviors are given in 55.Pa \*[Lt]sys/mman.h\*[Gt] : 56.Bd -literal 57#define MADV_NORMAL 0 /* no further special treatment */ 58#define MADV_RANDOM 1 /* expect random page references */ 59#define MADV_SEQUENTIAL 2 /* expect sequential references */ 60#define MADV_WILLNEED 3 /* will need these pages */ 61#define MADV_DONTNEED 4 /* don't need these pages */ 62#define MADV_SPACEAVAIL 5 /* ensure that resources are reserved */ 63#define MADV_FREE 6 /* pages are empty, free them */ 64.Ed 65.Sh SEE ALSO 66.Xr mincore 2 , 67.Xr mprotect 2 , 68.Xr msync 2 , 69.Xr munmap 2 70.Sh HISTORY 71The 72.Nm madvise 73system call first appeared in 74.Bx 4.4 , 75but until 76.Nx 1.5 77it did not perform any of the requests on, or change any behavior of the 78address range given. 79