Efficiency of Synchronous Versus Asynchronous Distributed Systems

A system of parallel processes is said to be synchronous if all processes run using the same clock, and it is said to be asynchronous if each process has its own independent clock. For any s, n, a particular distributed problem is defined involving system behavior at n ports. This problem can be solved in time s by a synchronous system but requires time at least (s-1)(log/sub b/n) on any asynchronous system, where b is a constant reflecting the communication bound in the model. This appears to be the first example of a problem for which an asynchronous system is probably slower than a synchronous one, and it shows that a straightforward step-by-step and process-by-process simulation of an n-process synchronous system by an n-process asynchronous system necessarily loses a factor of log/sub b/n in speed. 1 ref.