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man:mincore

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 res-
     idency  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  signifi-
     cant  bit  of  each  byte will be set if the corresponding page is cur-
     rently 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_mad-
     vise(3)

COLOPHON

     This  page  is  part of release 4.16 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)

/data/webs/external/dokuwiki/data/pages/man/mincore.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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