Manual page for msync(3C)
msync - synchronize memory with physical storage
SYNOPSIS
#include <sys/types.h>
#include <sys/mman.h>
int msync(caddr_t addr,
size_t len,
int flags);
MT-LEVEL
MT-Safe
DESCRIPTION
The function
msync()
writes all modified copies of pages over the range
[addr, addr + len)
to their backing storage locations.
msync()
optionally invalidates any copies so that further references to the pages
will be obtained by the system from their backing
storage locations.
The backing storage for a modified
MAP_SHARED
mapping is the file
the page is mapped to;
the backing storage for a modified
MAP_PRIVATE
mapping is its swap area.
flags
is a bit pattern built from the following values:
MS_ASYNC perform asynchronous writes
MS_SYNC perform synchronous writes
MS_INVALIDATE invalidate mappings
If
MS_ASYNC
is set,
msync()
returns immediately once all write operations are scheduled;
if
MS_SYNC
is set,
msync()
does not return until all write operations are completed.
MS_INVALIDATE
invalidates all cached copies of data in memory, so that further references
to the pages will be obtained by the system from their backing storage locations.
RETURN VALUES
Upon successful completion, the function
msync()
returns 0; otherwise, it returns -1 and
sets errno to indicate the error.
ERRORS
- EBUSY
-
Some or all of the addresses in the range
[addr, addr + len)
are locked and
MC_SYNC
with the
MS_INVALIDATE
option is specified.
- EINVAL
-
addr
is not a multiple of the page size as returned by
sysconf.3c
flags
is not some combination of
MS_ASYNC
and
MS_INVALIDATE.
- EIO
-
An I/O error occurred while reading from or writing to the file system.
- ENOMEM
-
Addresses in the range
[addr, addr + len)
are outside the valid range for
the address space of a process, or specify one or more pages
that are not
mapped.
- EPERM
-
MS_INVALIDATE
was specified and one or more of the pages is locked in memory.
SEE ALSO
mmap.2
memcntl.2
sysconf.3c
NOTES
msync()
should be used by programs that require a memory object to
be in a known state, such as in building transaction facilities.
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
