synchronize a mapped region
() system call writes all pages with
shared modifications in the specified region starting from
and continuing for
should be a multiple of the page size.
Any required synchronization of memory caches will also take place at this
time. Filesystem operations on a file that is mapped for shared modifications
are unpredictable except after an msync
argument is the bitwise OR of zero or
more of the following values:
MS_ASYNC Perform asynchronous writes.
MS_SYNC Perform synchronous writes.
MS_INVALIDATE Invalidate cached data after writing.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable
is set to indicate the error.
The following errors may be reported:
was specified and a portion of the specified region was locked with
- The specified flags
argument was invalid.
- The addr parameter was not
page aligned or addr and
size specify a region that would extend
beyond the end of the address space.
- Addresses in the specified region are outside the range
allowed for the address space of the process, or specify one or more pages
which are unmapped.
- An I/O error occurred while writing.
() function first appeared in
. It was modified to conform to
IEEE Std 1003.1b-1993
Writes are currently done synchronously even if the
flag is specified.