85 lines
3.1 KiB
Groff
85 lines
3.1 KiB
Groff
.\" $NetBSD: madvise.2,v 1.17 2002/08/11 13:17:35 yamt Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93
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.\"
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.Dd August 11, 2002
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.Dt MADVISE 2
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.Os
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.Sh NAME
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.Nm madvise
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.Nd give advice about use of memory
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include \*[Lt]sys/mman.h\*[Gt]
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.Ft int
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.Fn madvise "void *addr" "size_t len" "int behav"
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.Sh DESCRIPTION
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The
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.Fn madvise
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system call
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allows a process that has knowledge of its memory behavior
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to describe it to the system.
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The known behaviors are given in
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.Pa \*[Lt]sys/mman.h\*[Gt] :
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.Bd -literal
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#define MADV_NORMAL 0 /* no further special treatment */
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#define MADV_RANDOM 1 /* expect random page references */
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#define MADV_SEQUENTIAL 2 /* expect sequential references */
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#define MADV_WILLNEED 3 /* will need these pages */
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#define MADV_DONTNEED 4 /* don't need these pages */
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#define MADV_SPACEAVAIL 5 /* ensure that resources are reserved */
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#define MADV_FREE 6 /* pages are empty, free them */
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.Ed
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.Sh RETURN VALUES
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Upon successful completion,
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a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh SEE ALSO
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.Xr mincore 2 ,
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.Xr mprotect 2 ,
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.Xr msync 2 ,
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.Xr munmap 2
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.Sh HISTORY
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The
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.Nm madvise
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system call first appeared in
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.Bx 4.4 ,
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but until
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.Nx 1.5
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it did not perform any of the requests on, or change any behavior of the
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address range given.
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