MADVISE(2) | System Calls Manual | MADVISE(2) |
madvise
,
posix_madvise
— give advice
about use of memory
#include
<sys/mman.h>
int
madvise
(void
*addr, size_t len,
int behav);
int
posix_madvise
(void
*addr, size_t len,
int behav);
The
madvise
()
system call allows a process that has knowledge of its memory behavior to
describe it to the system. The posix_madvise
()
interface has the same effect, but returns the error value instead of only
setting errno.
The possible behaviors are:
MADV_NORMAL
MADV_RANDOM
MADV_SEQUENTIAL
MADV_WILLNEED
MADV_DONTNEED
MADV_SPACEAVAIL
MADV_FREE
Portable programs that call the
posix_madvise
()
interface should use the aliases POSIX_MADV_NORMAL
,
POSIX_MADV_RANDOM
,
POSIX_MADV_SEQUENTIAL
,
POSIX_MADV_WILLNEED
, and
POSIX_MADV_DONTNEED
rather than the flags described
above.
The madvise
() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate the
error.
If successful, the posix_madvise
()
function will return zero. Otherwise an error number will be returned to
indicate the error.
The posix_madvise
() system call conforms
to IEEE Std 1003.1-2008
(“POSIX.1”).
The madvise
() function first appeared in
SunOS 4.0 and has been available since OpenBSD 2.7.
The posix_madvise
() function first appeared in
OpenBSD 4.8.
The MADV_WILLNEED
behavior is ignored. The
MADV_SPACEAVAIL
behavior is not implemented and will
always fail.
December 26, 2019 | OpenBSD-6.9 |