Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

posix_madvise(3c) [opensolaris man page]

posix_madvise(3C)					   Standard C Library Functions 					 posix_madvise(3C)

NAME
posix_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 behavior 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_madvise() 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 characteristic 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 ALSO
mmap(2), madvise(3C), posix_madvise(3C), attributes(5), standards(5) SunOS 5.11 14 Jul 2008 posix_madvise(3C)

Check Out this Related Man Page

MADVISE(2)						      BSD System Calls Manual							MADVISE(2)

NAME
madvise, posix_madvise -- give advice about use of memory SYNOPSIS
#include <sys/mman.h> int madvise(void *addr, size_t len, int advice); int posix_madvise(void *addr, size_t len, int advice); DESCRIPTION
The madvise() system call allows a process that has knowledge of its memory behavior to describe it to the system. The advice passed in may be used by the system to alter its virtual memory paging strategy. This advice may improve application and system performance. The behavior specified in advice can only be one of the following values: MADV_NORMAL Indicates that the application has no advice to give on its behavior in the specified address range. This is the system default behavior. This is used with madvise() system call. POSIX_MADV_NORMAL Same as MADV_NORMAL but used with posix_madvise() system call. MADV_SEQUENTIAL Indicates that the application expects to access this address range in a sequential manner. This is used with madvise() system call. POSIX_MADV_SEQUENTIAL Same as MADV_SEQUENTIAL but used with posix_madvise() system call. MADV_RANDOM Indicates that the application expects to access this address range in a random manner. This is used with madvise() system call. POSIX_MADV_RANDOM Same as MADV_RANDOM but used with posix_madvise() system call. MADV_WILLNEED Indicates that the application expects to access this address range soon. This is used with madvise() system call. POSIX_MADV_WILLNEED Same as MADV_WILLNEED but used with posix_madvise() system call. MADV_DONTNEED Indicates that the application is not expecting to access this address range soon. This is used with madvise() system call. POSIX_MADV_DONTNEED Same as MADV_DONTNEED but used with posix_madvise() system call. MADV_FREE Indicates that the application will not need the information contained in this address range, so the pages may be reused right away. The address range will remain valid. This is used with madvise() system call. MADV_ZERO_WIRED_PAGES Indicates that the application would like the wired pages in this address range to be zeroed out if the address range is deallocated without first unwiring the pages (i.e. a munmap(2) without a preceding munlock(2) or the application quits). This is used with madvise() system call. The posix_madvise() behaves same as madvise() except that it uses values with POSIX_ prefix for the advice system call argument. RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
madvise() fails if one or more of the following are true: [EINVAL] The value of advice is incorrect. [EINVAL] The address range includes unallocated regions. [ENOMEM] The virtual address range specified by the addr and len are outside the range allowed for the address space. LEGACY SYNOPSIS
#include <sys/types.h> #include <sys/mman.h> int madvise(caddr_t addr, size_t len, int advice); int posix_madvise(caddr_t addr, size_t len, int advice); The include file <sys/types.h> is necessary. The type of addr has changed. SEE ALSO
mincore(2), minherit(2), mprotect(2), msync(2), munmap(2), compat(5) HISTORY
The madvise function first appeared in 4.4BSD. The posix_madvise function is part of IEEE 1003.1-2001 and was first implemented in Mac OS X 10.2. BSD
June 9, 1993 BSD
Man Page