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Diffstat (limited to 'lib/libc/sys/madvise.2')
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diff --git a/lib/libc/sys/madvise.2 b/lib/libc/sys/madvise.2 deleted file mode 100644 index 6d0d3d2575a6..000000000000 --- a/lib/libc/sys/madvise.2 +++ /dev/null @@ -1,186 +0,0 @@ -.\" Copyright (c) 1991, 1993 -.\" The Regents of the University of California. All rights reserved. -.\" -.\" Redistribution and use in source and binary forms, with or without -.\" modification, are permitted provided that the following conditions -.\" are met: -.\" 1. Redistributions of source code must retain the above copyright -.\" notice, this list of conditions and the following disclaimer. -.\" 2. Redistributions in binary form must reproduce the above copyright -.\" notice, this list of conditions and the following disclaimer in the -.\" documentation and/or other materials provided with the distribution. -.\" 3. Neither the name of the University nor the names of its contributors -.\" may be used to endorse or promote products derived from this software -.\" without specific prior written permission. -.\" -.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND -.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE -.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE -.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE -.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL -.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS -.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) -.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT -.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY -.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF -.\" SUCH DAMAGE. -.\" -.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93 -.\" $FreeBSD$ -.\" -.Dd July 12, 2015 -.Dt MADVISE 2 -.Os -.Sh NAME -.Nm madvise , posix_madvise -.Nd give advice about use of memory -.Sh LIBRARY -.Lb libc -.Sh SYNOPSIS -.In sys/mman.h -.Ft int -.Fn madvise "void *addr" "size_t len" "int behav" -.Ft int -.Fn posix_madvise "void *addr" "size_t len" "int behav" -.Sh DESCRIPTION -The -.Fn madvise -system call -allows a process that has knowledge of its memory behavior -to describe it to the system. -The -.Fn posix_madvise -interface is identical, except it returns an error number on error and does -not modify -.Va errno , -and is provided for standards conformance. -.Pp -The known behaviors are: -.Bl -tag -width MADV_SEQUENTIAL -.It Dv MADV_NORMAL -Tells the system to revert to the default paging -behavior. -.It Dv MADV_RANDOM -Is a hint that pages will be accessed randomly, and prefetching -is likely not advantageous. -.It Dv MADV_SEQUENTIAL -Causes the VM system to depress the priority of -pages immediately preceding a given page when it is faulted in. -.It Dv MADV_WILLNEED -Causes pages that are in a given virtual address range -to temporarily have higher priority, and if they are in -memory, decrease the likelihood of them being freed. -Additionally, -the pages that are already in memory will be immediately mapped into -the process, thereby eliminating unnecessary overhead of going through -the entire process of faulting the pages in. -This WILL NOT fault -pages in from backing store, but quickly map the pages already in memory -into the calling process. -.It Dv MADV_DONTNEED -Allows the VM system to decrease the in-memory priority -of pages in the specified address range. -Consequently, future references to this address range are more likely -to incur a page fault. -.It Dv MADV_FREE -Gives the VM system the freedom to free pages, -and tells the system that information in the specified page range -is no longer important. -This is an efficient way of allowing -.Xr malloc 3 -to free pages anywhere in the address space, while keeping the address space -valid. -The next time that the page is referenced, the page might be demand -zeroed, or might contain the data that was there before the -.Dv MADV_FREE -call. -References made to that address space range will not make the VM system -page the information back in from backing store until the page is -modified again. -.It Dv MADV_NOSYNC -Request that the system not flush the data associated with this map to -physical backing store unless it needs to. -Typically this prevents the -file system update daemon from gratuitously writing pages dirtied -by the VM system to physical disk. -Note that VM/file system coherency is -always maintained, this feature simply ensures that the mapped data is -only flush when it needs to be, usually by the system pager. -.Pp -This feature is typically used when you want to use a file-backed shared -memory area to communicate between processes (IPC) and do not particularly -need the data being stored in that area to be physically written to disk. -With this feature you get the equivalent performance with mmap that you -would expect to get with SysV shared memory calls, but in a more controllable -and less restrictive manner. -However, note that this feature is not portable -across UNIX platforms (though some may do the right thing by default). -For more information see the MAP_NOSYNC section of -.Xr mmap 2 -.It Dv MADV_AUTOSYNC -Undoes the effects of MADV_NOSYNC for any future pages dirtied within the -address range. -The effect on pages already dirtied is indeterminate - they -may or may not be reverted. -You can guarantee reversion by using the -.Xr msync 2 -or -.Xr fsync 2 -system calls. -.It Dv MADV_NOCORE -Region is not included in a core file. -.It Dv MADV_CORE -Include region in a core file. -.It Dv MADV_PROTECT -Informs the VM system this process should not be killed when the -swap space is exhausted. -The process must have superuser privileges. -This should be used judiciously in processes that must remain running -for the system to properly function. -.El -.Pp -Portable programs that call the -.Fn posix_madvise -interface should use the aliases -.Dv POSIX_MADV_NORMAL , POSIX_MADV_SEQUENTIAL , -.Dv POSIX_MADV_RANDOM , POSIX_MADV_WILLNEED , -and -.Dv POSIX_MADV_DONTNEED -rather than the flags described above. -.Sh RETURN VALUES -.Rv -std madvise -.Sh ERRORS -The -.Fn madvise -system call will fail if: -.Bl -tag -width Er -.It Bq Er EINVAL -The -.Fa behav -argument is not valid. -.It Bq Er ENOMEM -The virtual address range specified by the -.Fa addr -and -.Fa len -arguments is not valid. -.It Bq Er EPERM -.Dv MADV_PROTECT -was specified and the process does not have superuser privileges. -.El -.Sh SEE ALSO -.Xr mincore 2 , -.Xr mprotect 2 , -.Xr msync 2 , -.Xr munmap 2 , -.Xr posix_fadvise 2 -.Sh STANDARDS -The -.Fn posix_madvise -interface conforms to -.St -p1003.1-2001 . -.Sh HISTORY -The -.Fn madvise -system call first appeared in -.Bx 4.4 . |