NAME    [Toc]    [Back]

     msync -- synchronize a mapped region

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <sys/mman.h>

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

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

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


FreeBSD 5.2.1			 June 21, 1994			 FreeBSD 5.2.1