Section: Linux Programmer's Manual (2)
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mincore - get information on whether pages are in core
int mincore(void *start, size_t length, unsigned char *vec);
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
bytes following the
address. On return, the kernel will have filled
with bytes, of which the least significant bit indicates if a page is
core resident. (The other bits are undefined, reserved for possible
Of course this is only a snapshot: pages that are not
locked in core can come and go any moment, and the contents of
may be stale already when this call returns.
to return successfully,
must lie on a page boundary. It is the caller's responsibility to
round up to the nearest page. The
parameter need not be a multiple of the page size. The vector
must be large enough to contain (length+PAGE_SIZE-1) / PAGE_SIZE bytes.
One may obtain the page size from
On error, -1 is returned, and
is set appropriately.
kernel is temporarily out of resources
points to an invalid address
is not a multiple of the page size.
is greater than
(TASK_SIZE - start).
(This could occur if a negative value is specified for
since that value will be interpreted as a large
In Linux 2.6.11 and earlier, the error
was returned for this condition.
contained unmapped memory, or memory not part of a file.
Up to now (Linux 2.6.5),
does not return correct information for MAP_PRIVATE mappings.
is not specified in POSIX.1-2001,
and it is not available on all Unix implementations.
function first appeared in 4.4BSD.
Since Linux 2.3.99pre1 and glibc 2.2.
- RETURN VALUE
- CONFORMING TO
- SEE ALSO
linux.jgfs.net manual pages