Is parallelism for you?

This article offers practical, basic rules of thumb that can help you predict if parallelism might be worthwhile, given your application and the effort you want to invest. The techniques presented for estimating likely performance gains are drawn from the experiences of hundreds of computational scientists and engineers at national labs, universities, and research facilities. The information is more anecdotal than experimental, but it reflects the very real problems that must be overcome if parallel programming is to yield useful benefits