Name
mincore — determine whether pages are resident in memory
Synopsis
#include <unistd.h> #include <sys/mman.h>
int
mincore( |
void * | start, |
| size_t | length, | |
| unsigned char * | vec); |
![[Note]](../stylesheet/note.png) |
Note | ||
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DESCRIPTION
mincore() returns a vector
that indicates whether pages of the calling process's virtual
memory are resident in core (RAM), and so will not cause a
disk access (page fault) if referenced. The kernel returns
residency information about the pages starting at the address
start, and continuing
for length bytes.
The start argument
must be a multiple of the system page size. The length argument need not be a
multiple of the page size, but since residency information is
returned for whole pages, length is effectively rounded
up to the next multiple of the page size. One may obtain the
page size (PAGE_SIZE) using
sysconf(_SC_PAGESIZE).
The vec argument
must point to an array containing at least (length+PAGE_SIZE−1) /
PAGE_SIZE bytes. On return, the least significant
bit of each byte will be set if the corresponding page is
currently resident in memory, and be clear otherwise. (The
settings of the other bits in each byte are undefined; these
bits are reserved for possible later use.) Of course the
information returned in vec is only a snapshot: pages
that are not locked in memory can come and go at any moment,
and the contents of vec may already be stale by the
time this call returns.
RETURN VALUE
On success, mincore()
returns zero. On error, −1 is returned, and
errno is set appropriately.
ERRORS
EAGAIN kernel is temporarily out of resources.
- EFAULT
-
vecpoints to an invalid address. - EINVAL
-
startis not a multiple of the page size. - ENOMEM
-
lengthis greater than (TASK_SIZE−start). (This could occur if a negative value is specified forlength, since that value will be interpreted as a large unsigned integer.) In Linux 2.6.11 and earlier, the error EINVAL was returned for this condition. - ENOMEM
-
starttostart+lengthcontained unmapped memory.
CONFORMING TO
mincore() is not specified
in POSIX.1-2001, and it is not available on all Unix
implementations.
BUGS
Before kernel 2.6.21, mincore() did not return correct
information for MAP_PRIVATE
mappings, or for non-linear mappings (established using
remap_file_pages(2)).
COLOPHON
This page is part of release 2.79 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
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Copyright (C) 2001 Bert Hubert <ahuds9a.nl> and Copyright (C) 2007 Michael Kerrisk <mtk.manpagesgmail.com> Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. Created Sun Jun 3 17:23:32 2001 by bert hubert <ahuds9a.nl> Slightly adapted, following comments by Hugh Dickins, aeb, 2001-06-04. Modified, 20 May 2003, Michael Kerrisk <mtk.manpagesgmail.com> Modified, 30 Apr 2004, Michael Kerrisk <mtk.manpagesgmail.com> 2005-04-05 mtk, Fixed error descriptions after message from <gordon.jinintel.com> 2007-01-08 mtk, rewrote various parts |