The topic of how much parallelism there is in an application has gotten considerable debate, and the answer is “it depends.”

It certainly depends on the size of the problem to be solved and on the ability to find a suitable algorithm to take advantage of the parallelism. Much of this debate previously has been centered on making sure we write efficient and worthy programs for expensive and rare parallel computers. The definition of size, the efficiency required, and the expense of the computer have all changed with the emergence of multi-core processors. We need to step back and be sure we review the ground we are standing on. The world has changed.