The above graph shows HINT run on a scalable parallel computer. It plots logarithmic time on the x-axis and logarithmic QUIPS on the y-axis. There is initial overhead to run the program for more than one node, and overhead increases with number of nodes. Scalability of the computer is determined by the fact that the QUIPS increases uniformly with the increase of the number of nodes (power of 2).
Unscalable Parallel Computer