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mincore(2) [freebsd man page]

MINCORE(2)						      BSD System Calls Manual							MINCORE(2)

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. 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 "super" page. (only i386 & amd64) The information returned by mincore() may be out of date by the time the system call returns.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. 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. BSD
January 17, 2003 BSD

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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(): _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.1-2001, 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
mlock(2), mmap(2) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2008-04-22 MINCORE(2)

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