Performance loss between concept and keyboard
András Z. Salamon and Vashti Galpin
Standards bodies and commercial software vendors have defined parallel constructs to harness the parallelism in computations. Using the task graph model of parallel program execution, we show how common programming constructs that impose series-parallel task dependencies can lead to unbounded slowdown compared to the inherent parallelism in the algorithm. We describe various ways in which this slowdown can be avoided.