Where is time spent in message-passing and shared-memory programs?

Message passing and shared memory are two techniques parallel programs use for coordination and communication. This paper studies the strengths and weaknesses of these two mechanisms by comparing equivalent, well-written message-passing and shared-memory programs running on similar hardware. To ensure that our measurements are comparable, we produced two carefully tuned versions of each program and measured them on closely-related simulators of a message-passing and a shared-memory machine, both of which are based on same underlying hardware assumptions.