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

NAME

       mincore - determine whether pages are resident in memory

SYNOPSIS

       #include <unistd.h>
       #include <sys/mman.h>

       int mincore(void *addr, size_t length, unsigned char *vec);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mincore(): _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       mincore() returns a vector that indicates whether pages of the calling process's virtual memory are resident in core (RAM), and so will not
       cause a disk access (page fault) if referenced.	The kernel returns residency information about the pages starting at the address addr, and
       continuing for length bytes.

       The addr argument must be a multiple of the system page size.  The length argument need not be a multiple of the page size, but since resi-
       dency information is returned for whole pages, length is effectively rounded up to the next multiple of the page size.  One may obtain  the
       page size (PAGE_SIZE) using sysconf(_SC_PAGESIZE).

       The  vec  argument must point to an array containing at least (length+PAGE_SIZE-1) / PAGE_SIZE bytes.  On return, the least significant bit
       of each byte will be set if the corresponding page is currently resident in memory, and be clear otherwise.  (The  settings  of	the  other
       bits  in  each  byte  are  undefined; these bits are reserved for possible later use.)  Of course the information returned in vec is only a
       snapshot: pages that are not locked in memory can come and go at any moment, and the contents of vec may already be stale by the time  this
       call returns.

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 addr is not a multiple of the page size.

       ENOMEM length  is greater than (TASK_SIZE - addr).  (This could occur if a negative value is specified for length, 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 addr to addr + length contained unmapped memory.

VERSIONS

       Available since Linux 2.3.99pre1 and glibc 2.2.

CONFORMING TO

       mincore() is not specified in POSIX.1-2001, and it is not available on all Unix implementations.

BUGS

       Before kernel 2.6.21, mincore() did not return correct information for MAP_PRIVATE mappings, or for nonlinear mappings  (established  using
       remap_file_pages(2)).

SEE ALSO

       mlock(2), mmap(2)

COLOPHON

       This  page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2008-04-22								MINCORE(2)