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NAME    [Toc]    [Back]

       mincore - get information on whether pages are in core

SYNOPSIS    [Toc]    [Back]

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

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

DESCRIPTION    [Toc]    [Back]

       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.

       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    [Toc]    [Back]

       On  success, mincore returns zero.  On error, -1 is returned, and errno
       is set appropriately.

ERRORS    [Toc]    [Back]

       EAGAIN kernel is temporarily out of resources

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

       EFAULT vec points to an illegal address

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

BUGS    [Toc]    [Back]

       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    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

       The mincore() function first appeared in 4.4BSD.

AVAILABILITY    [Toc]    [Back]

       Since Linux 2.3.99pre1 and glibc 2.2.

SEE ALSO    [Toc]    [Back]

       getpagesize(2), mmap(2)

Linux 2.4.5			  2001-06-03			    MINCORE(2)
[ Back ]
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