Provided by: manpages-dev_2.17-1_all
mincore - get information on whether pages are in core
int mincore(void *start, size_t length, unsigned char *vec);
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
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).
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 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.
Up to now (Linux 2.6.5), mincore() does not return correct information
for MAP_PRIVATE mappings.
mincore() is not specified in POSIX.1-2001, and it is not available on
all Unix implementations.
The mincore() function first appeared in 4.4BSD.
Since Linux 2.3.99pre1 and glibc 2.2.
getpagesize(2), mlock(2), mmap(2)