1.\" $OpenBSD: madvise.2,v 1.12 2001/08/02 20:37:35 hugh 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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93 36.\" 37.Dd June 9, 1993 38.Dt MADVISE 2 39.Os 40.Sh NAME 41.Nm madvise 42.Nd give advice about use of memory 43.Sh SYNOPSIS 44.Fd #include <sys/types.h> 45.Fd #include <sys/mman.h> 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 possible behaviors are: 55.Bl -tag -width MADV_SEQUENTIAL 56.It Dv MADV_NORMAL 57No further special treatment needed. 58.It Dv MADV_RANDOM 59Expect random page access patterns. 60.It Dv MADV_SEQUENTIAL 61Expect sequential page references. 62.It Dv MADV_WILLNEED 63The pages will be referenced soon. 64.It Dv MADV_DONTNEED 65The pages will not be referenced soon. 66.It Dv MADV_SPACEAVAIL 67Ensure that resources are reserved. 68.It Dv MADV_FREE 69The pages don't contain any useful data and can be recycled. 70.El 71.Sh RETURN VALUES 72Upon successful completion, 73a value of 0 is returned. 74Otherwise, a value of \-1 is returned and 75.Va errno 76is set to indicate the error. 77.Sh SEE ALSO 78.Xr mincore 2 , 79.Xr minherit 2 , 80.Xr mprotect 2 , 81.Xr msync 2 , 82.Xr munmap 2 83.Sh HISTORY 84The 85.Nm madvise 86function first appeared in 87.Bx 4.4 . 88