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mincore(2) - mincore, mincore - get information on whether pages are in core - man 2 mincore

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



NAME
       mincore - get information on whether pages are in(1,8) 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(1,n)
       are in(1,8) core and can be read(2,n,1 builtins) without disk access. The kernel will supply
       data  for length bytes following the start address. On return, the ker-
       nel will have filled vec with bytes, of which the least significant bit
       indicates  if(3,n)  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(1,8) core can come and go any moment, and the
       contents of vec may be stale already when this call returns.

       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).


RETURN VALUE
       On success, mincore returns zero.  On error(8,n), -1 is returned, and  errno
       is set(7,n,1 builtins) appropriately.

ERRORS
       EAGAIN kernel is temporarily out of resources

       EFAULT vec points to an invalid address

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

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


BUGS
       Up  to  now  (Linux 2.6.5), mincore does not return correct information
       for MAP_PRIVATE mappings.


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

HISTORY
       The mincore() function first appeared in(1,8) 4.4BSD.

AVAILABILITY
       Since Linux 2.3.99pre1 and glibc 2.2.

SEE ALSO
       getpagesize(2), mlock(2), mmap(2)



Linux 2.6.5                       2004-04-30                        MINCORE(2)

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