mincore(2) -- Linux man page
NAMEmincore - get information on whether pages are in core
DESCRIPTIONThe mincore 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. (The other bits are undefined, reserved for possible later use.) Of course this is only a snapshot - pages that are not locked in core can come and go any moment, and the contents of vec may be stale already when this call returns.
For mincore 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-1) / PAGE_SIZE bytes. One may obtain the page size from getpagesize(2).
RETURN VALUEOn success, mincore returns zero. On error, -1 is returned, and errno is set appropriately.
ERRORSEAGAIN kernel is temporarily out of resources
- start is not a multiple of the page size, or len has a non-positive value
- vec points to an invalid address
contained unmapped memory, or memory not part of a file.
BUGSUp to now (Linux 2.6.5), mincore does not return correct information for MAP_PRIVATE mappings.
CONFORMING TOmincore does not appear to be part of POSIX or the Single Unix Specification.
HISTORYThe mincore() function first appeared in 4.4BSD.
AVAILABILITYSince Linux 2.3.99pre1 and glibc 2.2.
SEE ALSOgetpagesize(2), mlock(2), mmap(2)