On Wed, 4 Jul 2012, Stefan Ring wrote:
I really makes no sense at all to
have munmap(2) not imply msync(3C).
Why not? munmap(2) does basically the equivalent of write(2). In the
case of write, that is: a later read from the same location will see
the written data, unless another write happens in-between. If power
Actually, a write to memory for a memory mapped file is more similar
to write(2). If two programs have the same file mapped then the
effect on the memory they share is instantaneous because it is
the same physical memory. A mmapped file becomes shared memory as
soon as it is mapped at least twice.
It is pretty common for a system of applications to implement shared
memory via memory mapped files with the mapped memory used for
read/write. This is a precursor to POSIX's shm_open(3RT) which
produces similar functionality without a known file in the filesystem
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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