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MSYNC(2)                  FreeBSD System Calls Manual                 MSYNC(2)

NAME
     msync - synchronize a mapped region

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/mman.h>

     int
     msync(void *addr, size_t len, int flags);

DESCRIPTION
     The msync() system call writes any modified pages back to the file system
     and updates the file modification time.  If len is 0, all modified pages
     within the region containing addr will be flushed; if len is non-zero,
     only those pages containing addr and len-1 succeeding locations will be
     examined.  The flags argument may be specified as follows:

     MS_ASYNC           Return immediately
     MS_SYNC            Perform synchronous writes
     MS_INVALIDATE      Invalidate all cached data

RETURN VALUES
     The msync() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     The msync() system call will fail if:

     [EBUSY]            Some or all of the pages in the specified region are
                        locked and MS_INVALIDATE is specified.

     [EINVAL]           The addr argument is not a multiple of the hardware
                        page size.

     [EINVAL]           The len argument is too large or negative.

     [EINVAL]           The flags argument was both MS_ASYNC and
                        MS_INVALIDATE.  Only one of these flags is allowed.

SEE ALSO
     madvise(2), mincore(2), mlock(2), mprotect(2), munmap(2)

HISTORY
     The msync() system call first appeared in 4.4BSD.

FreeBSD 11.0-PRERELEASE          June 21, 1994         FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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