4f79d873c1
madvise().
This feature prevents the update daemon from gratuitously flushing
dirty pages associated with a mapped file-backed region of memory. The
system pager will still page the memory as necessary and the VM system
will still be fully coherent with the filesystem. Modifications made
by other means to the same area of memory, for example by write(), are
unaffected. The feature works on a page-granularity basis.
MAP_NOSYNC allows one to use mmap() to share memory between processes
without incuring any significant filesystem overhead, putting it in
the same performance category as SysV Shared memory and anonymous memory.
Reviewed by: julian, alc, dg
149 lines
5.1 KiB
C
149 lines
5.1 KiB
C
/*-
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* Copyright (c) 1982, 1986, 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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* @(#)mman.h 8.2 (Berkeley) 1/9/95
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* $FreeBSD$
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*/
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#ifndef _SYS_MMAN_H_
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#define _SYS_MMAN_H_
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#include <sys/_posix.h>
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/*
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* Protections are chosen from these bits, or-ed together
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*/
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#define PROT_NONE 0x00 /* no permissions */
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#define PROT_READ 0x01 /* pages can be read */
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#define PROT_WRITE 0x02 /* pages can be written */
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#define PROT_EXEC 0x04 /* pages can be executed */
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/*
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* Flags contain sharing type and options.
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* Sharing types; choose one.
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*/
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#define MAP_SHARED 0x0001 /* share changes */
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#define MAP_PRIVATE 0x0002 /* changes are private */
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#define MAP_COPY MAP_PRIVATE /* Obsolete */
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/*
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* Other flags
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*/
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#define MAP_FIXED 0x0010 /* map addr must be exactly as requested */
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#define MAP_RENAME 0x0020 /* Sun: rename private pages to file */
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#define MAP_NORESERVE 0x0040 /* Sun: don't reserve needed swap area */
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#define MAP_INHERIT 0x0080 /* region is retained after exec */
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#define MAP_NOEXTEND 0x0100 /* for MAP_FILE, don't change file size */
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#define MAP_HASSEMAPHORE 0x0200 /* region may contain semaphores */
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#define MAP_STACK 0x0400 /* region grows down, like a stack */
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#define MAP_NOSYNC 0x0800 /* page to but do not sync underlying file */
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#ifdef _P1003_1B_VISIBLE
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/*
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* Process memory locking
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*/
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#define MCL_CURRENT 0x0001 /* Lock only current memory */
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#define MCL_FUTURE 0x0002 /* Lock all future memory as well */
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#endif /* _P1003_1B_VISIBLE */
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/*
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* Error return from mmap()
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*/
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#define MAP_FAILED ((void *)-1)
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/*
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* msync() flags
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*/
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#define MS_SYNC 0x0000 /* msync synchronously */
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#define MS_ASYNC 0x0001 /* return immediately */
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#define MS_INVALIDATE 0x0002 /* invalidate all cached data */
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/*
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* Mapping type
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*/
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#define MAP_FILE 0x0000 /* map from file (default) */
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#define MAP_ANON 0x1000 /* allocated from memory, swap space */
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/*
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* Advice to madvise
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*/
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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 page references */
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#define MADV_WILLNEED 3 /* will need these pages */
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#define MADV_DONTNEED 4 /* dont need these pages */
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#define MADV_FREE 5 /* dont need these pages, and junk contents */
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#define MADV_NOSYNC 6 /* try to avoid flushes to physical media */
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#define MADV_AUTOSYNC 7 /* revert to default flushing strategy */
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/*
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* Return bits from mincore
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*/
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#define MINCORE_INCORE 0x1 /* Page is incore */
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#define MINCORE_REFERENCED 0x2 /* Page has been referenced by us */
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#define MINCORE_MODIFIED 0x4 /* Page has been modified by us */
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#define MINCORE_REFERENCED_OTHER 0x8 /* Page has been referenced */
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#define MINCORE_MODIFIED_OTHER 0x10 /* Page has been modified */
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#ifndef KERNEL
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#include <sys/cdefs.h>
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__BEGIN_DECLS
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#ifdef _P1003_1B_VISIBLE
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int mlockall __P((int));
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int munlockall __P((void));
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int shm_open __P((const char *, int, mode_t));
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int shm_unlink __P((const char *));
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#endif /* _P1003_1B_VISIBLE */
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int mlock __P((const void *, size_t));
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#ifndef _MMAP_DECLARED
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#define _MMAP_DECLARED
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void * mmap __P((void *, size_t, int, int, int, off_t));
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#endif
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int mprotect __P((const void *, size_t, int));
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int msync __P((void *, size_t, int));
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int munlock __P((const void *, size_t));
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int munmap __P((void *, size_t));
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#ifndef _POSIX_SOURCE
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int madvise __P((void *, size_t, int));
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int mincore __P((const void *, size_t, char *));
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int minherit __P((void *, size_t, int));
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#endif
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__END_DECLS
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#endif /* !KERNEL */
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#endif
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