POSIX_FADVISE(3C)POSIX_FADVISE(3C)NAMEposix_fadvise - file advisory information
SYNOPSIS
#include <fcntl.h>
int posix_fadvise(int fd, off_t offset, off_t len, int advice);
DESCRIPTION
The posix_fadvise() function advises the system on the expected behav‐
ior of the application with respect to the data in the file associated
with the open file descriptor, fd, starting at offset and continuing
for len bytes. The specified range need not currently exist in the
file. If len is zero, all data following offset is specified. The sys‐
tem may use this information to optimize handling of the specified
data. The posix_fadvise() function has no effect on the semantics of
other operations on the specified data, although it may affect the per‐
formance of other operations.
The advice to be applied to the data is specified by the advice parame‐
ter and may be one of the following values:
POSIX_FADV_NORMAL
Specifies that the application has no advice
to give on its behavior with respect to the
specified data. It is the default characteris‐
tic if no advice is given for an open file.
POSIX_FADV_SEQUENTIAL
Specifies that the application expects to
access the specified data sequentially from
lower offsets to higher offsets.
POSIX_FADV_RANDOM
Specifies that the application expects to
access the specified data in a random order.
POSIX_FADV_WILLNEED
Specifies that the application expects to
access the specified data in the near future.
POSIX_FADV_DONTNEED
Specifies that the application expects that it
will not access the specified data in the near
future.
POSIX_FADV_NOREUSE
Specifies that the application expects to
access the specified data once and then not
reuse it thereafter.
These values are defined in <fcntl.h>
RETURN VALUES
Upon successful completion, posix_fadvise() returns zero. Otherwise, an
error number is returned to indicate the error.
ERRORS
The posix_fadvise() function will fail if:
EBADF
The fd argument is not a valid file descriptor.
EINVAL
The value of advice is invalid, or the value of len is less
than zero.
ESPIPE
The fd argument is associated with a pipe or FIFO.
USAGE
The posix_fadvise() function has a transitional interface for 64-bit
file offsets. See lf64(5).
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 ALSOposix_madvise(3C), attributes(5), standards(5)
Jul 14, 2008 POSIX_FADVISE(3C)
