mincore - determine whether pages are resident in memory
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
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 residency 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
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.
On success, mincore() returns zero. On error, -1 is returned, and
errno is set appropriately.
EAGAIN kernel is temporarily out of resources.
vec points to an invalid address.
addr is not a multiple of the page size.
length is greater than (
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.
length contained unmapped memory.
Available since Linux 2.3.99pre1 and glibc 2.2.
mincore() is not specified in POSIX.1, and it is not available on all UNIX implementations.
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/.