Eugene Loh wrote:
I don't understand what "waste" or "redundant calculations" you're referring to here. Let's say each cell is updated based on itself and neighboring values. Each cell has a unique "owner" who computes the updated value. That value is shared with neighbors if the cell is near the subdomain surface. So, there is a communication cost, but typically each new value is computed by only one process.
You are right, the overhead is in communication. Redundant information (on the overlap), not redundant calculation, is the right way to put it. Gus Correa
