madvise(2) - NetBSD Manual Pages

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MADVISE(2)                NetBSD System Calls Manual                MADVISE(2)


NAME

     madvise - give advice about use of memory


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/mman.h>

     int
     madvise(void *addr, size_t len, int behav);


DESCRIPTION

     The madvise() system call allows a process that has knowledge of its mem-
     ory behavior to describe it to the system.  The known behaviors are given
     in <sys/mman.h>:

     #define MADV_NORMAL     0       /* no further special treatment */
     #define MADV_RANDOM     1       /* expect random page references */
     #define MADV_SEQUENTIAL 2       /* expect sequential references */
     #define MADV_WILLNEED   3       /* will need these pages */
     #define MADV_DONTNEED   4       /* don't need these pages */
     #define MADV_SPACEAVAIL 5       /* ensure that resources are reserved */
     #define MADV_FREE       6       /* pages are empty, free them */


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.


SEE ALSO

     mincore(2), mprotect(2), msync(2), munmap(2)


HISTORY

     The madvise system call first appeared in 4.4BSD, but until NetBSD 1.5 it
     did not perform any of the requests on, or change any behavior of the
     address range given.

NetBSD 2.1                      August 11, 2002                     NetBSD 2.1