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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | BUGS | SEE ALSO | COLOPHON |
MINCORE(2) Linux Programmer's Manual MINCORE(2)
mincore - determine whether pages are resident in memory
#include <unistd.h>
#include <sys/mman.h>
int mincore(void *addr, size_t length, unsigned char *vec);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
mincore():
Since glibc 2.19:
_DEFAULT_SOURCE
Glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
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
addr, and continuing for length bytes.
The addr 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.
On success, mincore() returns zero. On error, -1 is returned, and
errno is set appropriately.
EAGAIN kernel is temporarily out of resources.
EFAULT vec points to an invalid address.
EINVAL addr is not a multiple of the page size.
ENOMEM length is greater than (TASK_SIZE - addr). (This could occur
if a negative value is specified for length, 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 addr to addr + length contained unmapped memory.
Available since Linux 2.3.99pre1 and glibc 2.2.
mincore() is not specified in POSIX.1, and it is not available on all
UNIX implementations.
Before kernel 2.6.21, mincore() did not return correct information
for MAP_PRIVATE mappings, or for nonlinear mappings (established
using remap_file_pages(2)).
fincore(1), madvise(2), mlock(2), mmap(2), posix_fadvise(2),
posix_madvise(3)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2017-05-03 MINCORE(2)
Pages that refer to this page: fincore(1), madvise(2), mlock(2), mmap(2), posix_fadvise(2), syscalls(2)