mincore.2 (2010 09)

mincore(2) mincore(2)

NAME

mincore() - determine residency of memory pages

SYNOPSIS

#include <sys/mman.h>

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

DESCRIPTION

The mincore() function determines the residency of the memory pages speciﬁed by the range [addr ,

addr +len ]. The status is returned as a character-per-page in the character array referenced by vec . The

least signiﬁcant bit of each character is set to 1 to indicate the referenced page is in memory and to 0 to

indicate that it is not. The settings of other bits in each character are undeﬁned and may contain other

information about a page in future implementations.

This system call returns the status of all memory pages within the range, addr to addr+len . The addr

parameter is automatically rounded down to the nearest page size as returned by

sysconf(_SC_PAGE_SIZE)

system call. If the len value is not a multiple of the page size as returned

by the

sysconf(_SC_PAGE_SIZE)

system call, the end of the range is rounded up to the next multiple

of the page size.

The vector vec must be large enough to contain one byte per memory page within the address range.

Warnings

Because the status of a page can change between the time

mincore() checks and returns the informa-

tion, returned information might be outdated. Only locked pages are guaranteed to remain in memory.

See mlock (2).

RETURN VALUE

Upon successful completion,

mincore() returns 0. Otherwise, it returns −1 and sets errno to indicate

the error.

ERRORS

The

mincore() function will fail if:

[EFAULT] The vec argument points to an illegal address or an address for which the caller

does not have write mode access.

[EINVAL] len argument has a value less than or equal to 0.

[EINVAL] Addresses in the range [addr , addr +len ] span beyond the address space of a 64-bit

process.

[ENOMEM] Addresses in the range [addr , addr +len ] are invalid or not mapped for the address

space of a process.