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mincore() - Unix, Linux System Call
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NAME
mincore - get information on whether pages are in core
SYNOPSIS
#include <unistd.h>
#include <sys/mman.h>
int mincore(void *start, size_t length, unsigned char *vec); DESCRIPTION
The
mincore() function requests a vector describing which pages of a file are in core and
can be read without disk access. The kernel will supply data for
length bytes following the
start address. On return, the kernel will have filled
vec with bytes, of which the least significant bit indicates if a page is
core resident. (The other bits are undefined, reserved for possible
later use.)
Of course this is only a snapshot: pages that are not
locked in core can come and go any moment, and the contents of
vec may be stale already when this call returns.
For
mincore() to return successfully,
start must lie on a page boundary. It is the callers responsibility to
round up to the nearest page. The
length parameter need not be a multiple of the page size. The vector
vec must be large enough to contain (length+PAGE_SIZE-1) / PAGE_SIZE bytes.
One may obtain the page size from
getpagesize(2).
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
Tag | Description |
EFAULT |
vec points to an invalid address
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EINVAL |
start is not a multiple of the page size.
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ENOMEM |
len is greater than
(TASK_SIZE - start). (This could occur if a negative value is specified for
len, 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 |
address to
address +
length contained unmapped memory, or memory not part of a file.
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BUGS
Up to now (Linux 2.6.5),
mincore() does not return correct information for MAP_PRIVATE mappings.
CONFORMING TO
mincore() is not specified in POSIX.1-2001,
and it is not available on all Unix implementations.
HISTORY
The
mincore() function first appeared in 4.4BSD.
AVAILABILITY
Since Linux 2.3.99pre1 and glibc 2.2.
SEE ALSO
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