Peterson's algorithm is a concurrent programming algorithm for mutual exclusion that allows two processes to share a single-use resource without conflict, using only shared memory for communication. It was formulated by Gary Peterson in 1981 at the University of Rochester. While Peterson's original formulation worked with only two processes, the algorithm can be generalised for more than two, as discussed in "Operating Systems Review, January 1990 ('Proof of a Mutual Exclusion Algorithm', M Hofri)".
When working at the hardware level, Peterson's algorithm is typically not needed to achieve atomic access. Some processors have special instructions, like test-and-set or compare-and-swap that, by locking the memory bus, can be used to provide mutual exclusion in SMP systems.
Reference:
http://en.wikipedia.org/wiki/Peterson%27s_algorithm
