redhat man page for mincore

MINCORE(2)						     Linux Programmer's Manual							MINCORE(2)

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 signif-
       icant bit indicates if a page is core resident.

       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  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

       EINVAL start is not a multiple of the page size, or len has a non-positive value

       EFAULT vec points to an invalid address

       ENOMEM address to address + length contained unmapped memory, or memory not part of a file.

BUGS
       mincore	should	return a bit vector and not a byte vector. As of Linux 2.4.5, it is not possible to gain information on the core residency
       of pages which are not backed by a file.  In other words, calling mincore on an region returned by an anonymous mmap(2) does not  work  and
       sets errno to ENOMEM. Unless pages are locked in memory, the contents of vec may be stale by the time they reach userspace.

CONFORMING TO
       mincore does not appear to be part of POSIX or the Single Unix Specification.

HISTORY
       The mincore() function first appeared in 4.4BSD.

AVAILABILITY
       Since Linux 2.3.99pre1 and glibc 2.2.

SEE ALSO
       getpagesize(2), mmap(2)

Linux 2.4.5							    2001-06-03								MINCORE(2)