#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
Fa len
is 0, all modified pages within the region containing
Fa addr
will be flushed;
if
Fa len
is non-zero, only those pages containing
Fa addr
and
Fa len-1
succeeding locations will be examined.
The
Fa flags
argument may be specified as follows:
MS_ASYNC
Return immediately
MS_SYNC
Perform synchronous writes
MS_INVALIDATE
Invalidate all cached data
RETURN VALUES
Rv -std msync
ERRORS
The
msync ();
system call
will fail if:
Bq Er EBUSY
Some or all of the pages in the specified region are locked and
MS_INVALIDATE
is specified.
Bq Er EINVAL
The
Fa addr
argument
is not a multiple of the hardware page size.
Bq Er EINVAL
The
Fa len
argument
is too large or negative.
Bq Er EINVAL
The
Fa flags
argument
was both MS_ASYNC and MS_INVALIDATE.
Only one of these flags is allowed.
The
msync ();
system call first appeared in
BSD 4.4
BUGS
The
msync ();
system call is obsolete since
BSD implements a coherent file system buffer cache.
However, it may be used to associate dirty VM pages with file system
buffers and thus cause them to be flushed to physical media sooner
rather than later.
