On 2008-05-21, at 10:06, Martin Berger wrote:

> Here I disagree. Shared  memory concurrency is a specific form
> of message passing: Writing to a memory cell is in fact sending
> a message to that cell carrying two items, the new value and a
> return channel that is used to inform the writer that sending
> has succeeded, and likewise for reading.

This is completely wrong.  A few machines have a simple model like
that, but they were all built in the last century.  Nowadays, writing
to memory is more like broadcasting a message and having no idea when
it will arrive at each destination.  And if you write to another piece
of memory, you don't know in what order the updates will become
visible to a given processor.

You are neglecting a very important parameter, which is called the
"memory model" of your multiprocessor.

-- Damien