|POSIX_MADVISE(3P)||POSIX Programmer's Manual||POSIX_MADVISE(3P)|
PROLOGThis manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAMEposix_madvise - memory advisory information and alignment control ( ADVANCED REALTIME)
DESCRIPTIONThe posix_madvise() function need only be supported if either the Memory Mapped Files or the Shared Memory Objects options are supported.
The posix_madvise() function shall advise the implementation on the expected behavior of the application with respect to the data in the memory starting at address addr, and continuing for len bytes. The implementation may use this information to optimize handling of the specified data. The posix_madvise() function shall have no effect on the semantics of access to memory in the specified range, although it may affect the performance of access.
The implementation may require that addr be a multiple of the page size, which is the value returned by sysconf() when the name value _SC_PAGESIZE is used.
The advice to be applied to the memory range is specified by the advice parameter and may be one of the following values:
These values are defined in the <sys/mman.h> header.
RETURN VALUEUpon successful completion, posix_madvise() shall return zero; otherwise, an error number shall be returned to indicate the error.
ERRORSThe posix_madvise() function shall fail if:
- The value of advice is invalid.
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:
- The value of addr is not a multiple of the value returned by sysconf() when the name value _SC_PAGESIZE is used.
The value of
len is zero.
The following sections are informative.
APPLICATION USAGEThe posix_madvise() function is part of the Advisory Information option and need not be provided on all implementations.
SEE ALSOmmap(), posix_fadvise(), sysconf(), the Base Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h>
COPYRIGHTPortions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
|2003||IEEE/The Open Group|