mincore(2) [redhat man page]

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)

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():
	   Since glibc 2.19:
	       _DEFAULT_SOURCE
	   Glibc 2.19 and earlier:
	       _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, 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

       fincore(1), madvise(2), mlock(2), mmap(2), posix_fadvise(2), posix_madvise(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux								    2017-09-15								MINCORE(2)