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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_INVALI-
			DATE.  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	11.1			 June 21, 1994			  FreeBSD 11.1

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

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