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!!NAME mincore - get information on whether pages are in core !!SYNOPSIS #include <unistd.h> #include <sys/mman.h> __int mincore(void *__''start''__, size_t__ ''length''__, unsigned char *__ ''vec''__);__ !!DESCRIPTION The mincore(2) function requests a vector describing which pages of a file are in core and can be read without disk access. The kernel will supply data for ''length'' bytes following the ''start'' address. On return, the kernel will have filled ''vec'' with bytes, of which the least significant bit indicates if a page is core resident. For mincore(2) to return successfully, ''start'' must lie on a page boundary. It is the caller's responsibility to round up to the nearest page. The ''length'' parameter need not be a multiple of the page size. The vector ''vec'' must be large enough to contain length/PAGE_SIZE bytes. One may obtain the page size from getpagesize(2). !!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 ;[EINVAL]: is not a multiple of the page size, or has a non-positive value ;[EFAULT]: ''vec'' points to an illegal address ;[ENOMEM]: ''address'' to ''address'' + ''length'' contained unmapped memory, or memory not part of a file. !!BUGS mincore(2) should return a bit vector and not a byte vector. As of Linux 2.4.5, it is not possible to gain information on the core residency of pages which are not backed by a file. In other words, calling mincore(2) on an region returned by an anonymous mmap(2) does not work and sets errno to [ENOMEM]. Unless pages are locked in memory, the contents of ''vec'' may be stale by the time they reach userspace. !!CONFORMING TO mincore(2) does not appear to be part of POSIX or the Single Unix Specification. !!HISTORY The mincore(2) function first appeared in 4.4BSD. !!AVAILABILITY Since Linux 2.3.99pre1 and glibc 2.2. !!SEE ALSO getpagesize(2), mmap(2)
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