MINCORE
Section: Linux Programmer's Manual (2)
Updated: 2004-04-30
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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 caller's 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
- EFAULT
-
vec
points to an invalid address
- EINVAL
-
start
is not a multiple of the page size.
- 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.
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
getpagesize(2),
mlock(2),
mmap(2)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- BUGS
-
- CONFORMING TO
-
- HISTORY
-
- AVAILABILITY
-
- SEE ALSO
-
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