GSP
Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Support
Contact Us
Online Help
Handbooks
Domain Status
Man Pages

FAQ
Virtual Servers
Pricing
Billing
Technical

Network
Facilities
Connectivity
Topology Map

Miscellaneous
Server Agreement
Year 2038
Credits
 

USA Flag

 

 

Man Pages
POSIX_FADVISE(2) FreeBSD System Calls Manual POSIX_FADVISE(2)

posix_fadvise
give advice about use of file data

Standard C Library (libc, -lc)

#include <fcntl.h>

int
posix_fadvise(int fd, off_t offset, off_t len, int advice);

The posix_fadvise() system call allows a process to describe to the system its data access behavior for an open file descriptor fd. The advice covers the data starting at offset offset and continuing for len bytes. If len is zero, all data from offset to the end of the file is covered.

The behavior is specified by the advice parameter and may be one of:

Tells the system to revert to the default data access behavior.
Is a hint that file data will be accessed randomly, and prefetching is likely not advantageous.
Tells the system that file data will be accessed sequentially. This currently does nothing as the default behavior uses heuristics to detect sequential behavior.
Tells the system that the specified data will be accessed in the near future. The system may initiate an asynchronous read of the data if it is not already present in memory.
Tells the system that the specified data will not be accessed in the near future. The system may decrease the in-memory priority of clean data within the specified range and future access to this data may require a read operation.
Tells the system that the specified data will only be accessed once and then not reused. The system may decrease the in-memory priority of data once it has been read or written. Future access to this data may require a read operation.

If successful, posix_fadvise() returns zero. It returns an error on failure, without setting errno.

Possible failure conditions:
[]
The fd argument is not a valid file descriptor.
[]
The advice argument is not valid.
[]
The offset or len arguments are negative, or offset + len is greater than the maximum file size.
[]
The fd argument does not refer to a regular file.
[]
The fd argument is associated with a pipe or FIFO.
[]
An I/O error occurred while reading from or writing to a file system.
[]
Corrupted data was detected while reading from the file system.

madvise(2)

The posix_fadvise() interface conforms to IEEE Std 1003.1-2001 (“POSIX.1”).

The posix_fadvise() system call first appeared in FreeBSD 9.1.
March 30, 2020 FreeBSD 13.1-RELEASE

Search for    or go to Top of page |  Section 2 |  Main Index

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.