Thanks Dmitriy!

>> Can someone give a simple example of how this asymmetry can be used to achieve something more efficient than a full fence?
One more example using Peterson's lock, with an introduction to C++0x atomics:
http://bartoszmilewski.wordpress.com...mory-ordering/
(with corrections, thanks to Dmitriy and Anthony)
http://www.justsoftwaresolutions.co....x_atomics.html

gg