NAME

     mincore — determine residency of memory pages

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/mman.h>

     int
     mincore(const void *addr, size_t len, char *vec);

DESCRIPTION

     The mincore() system call determines whether each of the pages in the region beginning at
     addr and continuing for len bytes is resident or mapped, depending on the value of sysctl
     vm.mincore_mapped.  The status is returned in the vec array, one character per page.  Each
     character is either 0 if the page is not resident, or a combination of the following flags
     (defined in <sys/mman.h>):

     MINCORE_INCORE            Page is in core (resident).

     MINCORE_REFERENCED        Page has been referenced by us.

     MINCORE_MODIFIED          Page has been modified by us.

     MINCORE_REFERENCED_OTHER  Page has been referenced.

     MINCORE_MODIFIED_OTHER    Page has been modified.

     MINCORE_SUPER             Page is part of a large (“super”) page.

     The information returned by mincore() may be out of date by the time the system call
     returns.  The only way to ensure that a page is resident is to lock it into memory with the
     mlock(2) system call.

     If the vm.mincore_mapped sysctl is set to a non-zero value (default), only the current
     process' mappings of the pages in the specified virtual address range are examined.  This
     does not preclude the system from returning MINCORE_REFERENCED_OTHER and
     MINCORE_MODIFIED_OTHER statuses.  Otherwise, if the sysctl value is zero, all resident pages
     backing the specified address range are examined, regardless of the mapping state.

RETURN VALUES

     The mincore() function returns the value 0 if successful; otherwise the value -1 is returned
     and the global variable errno is set to indicate the error.

ERRORS

     The mincore() system call will fail if:

     [ENOMEM]           The virtual address range specified by the addr and len arguments is not
                        fully mapped.

     [EFAULT]           The vec argument points to an illegal address.

SEE ALSO

     madvise(2), mlock(2), mprotect(2), msync(2), munmap(2), getpagesize(3)

HISTORY

     The mincore() system call first appeared in 4.4BSD.