POSIX_MADVISE(3C)POSIX_MADVISE(3C)NAMEposix_madvise - memory advisory information
SYNOPSIS
#include <sys/mman.h>
int posix_madvise(void *addr, size_t len, int advice);
DESCRIPTION
The posix_madvise() function advises the system on the expected behav‐
ior of the application with respect to the data in the memory starting
at address addr, and continuing for len bytes. The system may use this
information to optimize handling of the specified data. The posix_mad‐
vise() function has no effect on the semantics of access to memory in
the specified range, although it may affect the performance of access.
The advice to be applied to the memory range is specified by the advice
parameter and may be one of the following values:
POSIX_MADV_NORMAL
Specifies that the application has no advice
to give on its behavior with respect to the
specified range. It is the default character‐
istic if no advice is given for a range of
memory.
POSIX_MADV_SEQUENTIAL
Specifies that the application expects to
access the specified range sequentially from
lower addresses to higher addresses.
POSIX_MADV_RANDOM
Specifies that the application expects to
access the specified range in a random order.
POSIX_MADV_WILLNEED
Specifies that the application expects to
access the specified range in the near future.
POSIX_MADV_DONTNEED
Specifies that the application expects that it
will not access the specified range in the
near future.
These values are defined in <sys/mman.h>
RETURN VALUES
Upon successful completion, posix_madvise() returns zero. Otherwise, an
error number is returned to indicate the error.
ERRORS
The posix_madvise() function will fail if:
EINVAL
The value of advice is invalid.
ENOMEM
Addresses in the range starting at addr and continuing for
len bytes are partly or completely outside the range allowed
for the address space of the calling process.
The posix_madvise() function may fail if:
EINVAL
The value of len is zero.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬───────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼───────────────────┤
│Interface Stability │ Committed │
├────────────────────┼───────────────────┤
│MT-Level │ MT-Safe │
├────────────────────┼───────────────────┤
│Standard │ See standards(5). │
└────────────────────┴───────────────────┘
SEE ALSOmmap(2), madvise(3C), posix_madvise(3C), attributes(5), standards(5)
Jul 14, 2008 POSIX_MADVISE(3C)
